Greg Kroah-Hartman | b244131 | 2017-11-01 15:07:57 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * linux/fs/namei.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * Some corrections by tytso. |
| 10 | */ |
| 11 | |
| 12 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname |
| 13 | * lookup logic. |
| 14 | */ |
| 15 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. |
| 16 | */ |
| 17 | |
| 18 | #include <linux/init.h> |
Paul Gortmaker | 630d9c4 | 2011-11-16 23:57:37 -0500 | [diff] [blame] | 19 | #include <linux/export.h> |
David S. Miller | 4469690 | 2012-05-23 20:12:50 -0700 | [diff] [blame] | 20 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/slab.h> |
| 22 | #include <linux/fs.h> |
| 23 | #include <linux/namei.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/pagemap.h> |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 25 | #include <linux/fsnotify.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | #include <linux/personality.h> |
| 27 | #include <linux/security.h> |
Mimi Zohar | 6146f0d | 2009-02-04 09:06:57 -0500 | [diff] [blame] | 28 | #include <linux/ima.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/syscalls.h> |
| 30 | #include <linux/mount.h> |
| 31 | #include <linux/audit.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 32 | #include <linux/capability.h> |
Trond Myklebust | 834f2a4 | 2005-10-18 14:20:16 -0700 | [diff] [blame] | 33 | #include <linux/file.h> |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 34 | #include <linux/fcntl.h> |
Serge E. Hallyn | 08ce5f1 | 2008-04-29 01:00:10 -0700 | [diff] [blame] | 35 | #include <linux/device_cgroup.h> |
Al Viro | 5ad4e53 | 2009-03-29 19:50:06 -0400 | [diff] [blame] | 36 | #include <linux/fs_struct.h> |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 37 | #include <linux/posix_acl.h> |
Linus Torvalds | 99d263d | 2014-09-13 11:30:10 -0700 | [diff] [blame] | 38 | #include <linux/hash.h> |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 39 | #include <linux/bitops.h> |
Eric W. Biederman | aeaa4a7 | 2016-07-23 11:20:44 -0500 | [diff] [blame] | 40 | #include <linux/init_task.h> |
Linus Torvalds | 7c0f6ba | 2016-12-24 11:46:01 -0800 | [diff] [blame] | 41 | #include <linux/uaccess.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | |
Eric Paris | e81e3f4 | 2009-12-04 15:47:36 -0500 | [diff] [blame] | 43 | #include "internal.h" |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 44 | #include "mount.h" |
Eric Paris | e81e3f4 | 2009-12-04 15:47:36 -0500 | [diff] [blame] | 45 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | /* [Feb-1997 T. Schoebel-Theuer] |
| 47 | * Fundamental changes in the pathname lookup mechanisms (namei) |
| 48 | * were necessary because of omirr. The reason is that omirr needs |
| 49 | * to know the _real_ pathname, not the user-supplied one, in case |
| 50 | * of symlinks (and also when transname replacements occur). |
| 51 | * |
| 52 | * The new code replaces the old recursive symlink resolution with |
| 53 | * an iterative one (in case of non-nested symlink chains). It does |
| 54 | * this with calls to <fs>_follow_link(). |
| 55 | * As a side effect, dir_namei(), _namei() and follow_link() are now |
| 56 | * replaced with a single function lookup_dentry() that can handle all |
| 57 | * the special cases of the former code. |
| 58 | * |
| 59 | * With the new dcache, the pathname is stored at each inode, at least as |
| 60 | * long as the refcount of the inode is positive. As a side effect, the |
| 61 | * size of the dcache depends on the inode cache and thus is dynamic. |
| 62 | * |
| 63 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink |
| 64 | * resolution to correspond with current state of the code. |
| 65 | * |
| 66 | * Note that the symlink resolution is not *completely* iterative. |
| 67 | * There is still a significant amount of tail- and mid- recursion in |
| 68 | * the algorithm. Also, note that <fs>_readlink() is not used in |
| 69 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() |
| 70 | * may return different results than <fs>_follow_link(). Many virtual |
| 71 | * filesystems (including /proc) exhibit this behavior. |
| 72 | */ |
| 73 | |
| 74 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: |
| 75 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL |
| 76 | * and the name already exists in form of a symlink, try to create the new |
| 77 | * name indicated by the symlink. The old code always complained that the |
| 78 | * name already exists, due to not following the symlink even if its target |
| 79 | * is nonexistent. The new semantics affects also mknod() and link() when |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 80 | * the name is a symlink pointing to a non-existent name. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 81 | * |
| 82 | * I don't know which semantics is the right one, since I have no access |
| 83 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" |
| 84 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the |
| 85 | * "old" one. Personally, I think the new semantics is much more logical. |
| 86 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing |
| 87 | * file does succeed in both HP-UX and SunOs, but not in Solaris |
| 88 | * and in the old Linux semantics. |
| 89 | */ |
| 90 | |
| 91 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink |
| 92 | * semantics. See the comments in "open_namei" and "do_link" below. |
| 93 | * |
| 94 | * [10-Sep-98 Alan Modra] Another symlink change. |
| 95 | */ |
| 96 | |
| 97 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: |
| 98 | * inside the path - always follow. |
| 99 | * in the last component in creation/removal/renaming - never follow. |
| 100 | * if LOOKUP_FOLLOW passed - follow. |
| 101 | * if the pathname has trailing slashes - follow. |
| 102 | * otherwise - don't follow. |
| 103 | * (applied in that order). |
| 104 | * |
| 105 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT |
| 106 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. |
| 107 | * During the 2.4 we need to fix the userland stuff depending on it - |
| 108 | * hopefully we will be able to get rid of that wart in 2.5. So far only |
| 109 | * XEmacs seems to be relying on it... |
| 110 | */ |
| 111 | /* |
| 112 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) |
Arjan van de Ven | a11f3a0 | 2006-03-23 03:00:33 -0800 | [diff] [blame] | 113 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | * any extra contention... |
| 115 | */ |
| 116 | |
| 117 | /* In order to reduce some races, while at the same time doing additional |
| 118 | * checking and hopefully speeding things up, we copy filenames to the |
| 119 | * kernel data space before using them.. |
| 120 | * |
| 121 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). |
| 122 | * PATH_MAX includes the nul terminator --RR. |
| 123 | */ |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 124 | |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 125 | #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 126 | |
David Drysdale | 51f39a1 | 2014-12-12 16:57:29 -0800 | [diff] [blame] | 127 | struct filename * |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 128 | getname_flags(const char __user *filename, int flags, int *empty) |
| 129 | { |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 130 | struct filename *result; |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 131 | char *kname; |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 132 | int len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | |
Jeff Layton | 7ac8626 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 134 | result = audit_reusename(filename); |
| 135 | if (result) |
| 136 | return result; |
| 137 | |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 138 | result = __getname(); |
Linus Torvalds | 3f9f0aa | 2012-04-28 14:38:32 -0700 | [diff] [blame] | 139 | if (unlikely(!result)) |
Eric Paris | 4043cde | 2012-01-03 14:23:08 -0500 | [diff] [blame] | 140 | return ERR_PTR(-ENOMEM); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 141 | |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 142 | /* |
| 143 | * First, try to embed the struct filename inside the names_cache |
| 144 | * allocation |
| 145 | */ |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 146 | kname = (char *)result->iname; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 147 | result->name = kname; |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 148 | |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 149 | len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 150 | if (unlikely(len < 0)) { |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 151 | __putname(result); |
| 152 | return ERR_PTR(len); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 153 | } |
Linus Torvalds | 3f9f0aa | 2012-04-28 14:38:32 -0700 | [diff] [blame] | 154 | |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 155 | /* |
| 156 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a |
| 157 | * separate struct filename so we can dedicate the entire |
| 158 | * names_cache allocation for the pathname, and re-do the copy from |
| 159 | * userland. |
| 160 | */ |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 161 | if (unlikely(len == EMBEDDED_NAME_MAX)) { |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 162 | const size_t size = offsetof(struct filename, iname[1]); |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 163 | kname = (char *)result; |
| 164 | |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 165 | /* |
| 166 | * size is chosen that way we to guarantee that |
| 167 | * result->iname[0] is within the same object and that |
| 168 | * kname can't be equal to result->iname, no matter what. |
| 169 | */ |
| 170 | result = kzalloc(size, GFP_KERNEL); |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 171 | if (unlikely(!result)) { |
| 172 | __putname(kname); |
| 173 | return ERR_PTR(-ENOMEM); |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 174 | } |
| 175 | result->name = kname; |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 176 | len = strncpy_from_user(kname, filename, PATH_MAX); |
| 177 | if (unlikely(len < 0)) { |
| 178 | __putname(kname); |
| 179 | kfree(result); |
| 180 | return ERR_PTR(len); |
| 181 | } |
| 182 | if (unlikely(len == PATH_MAX)) { |
| 183 | __putname(kname); |
| 184 | kfree(result); |
| 185 | return ERR_PTR(-ENAMETOOLONG); |
| 186 | } |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 187 | } |
| 188 | |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 189 | result->refcnt = 1; |
Linus Torvalds | 3f9f0aa | 2012-04-28 14:38:32 -0700 | [diff] [blame] | 190 | /* The empty path is special. */ |
| 191 | if (unlikely(!len)) { |
| 192 | if (empty) |
Eric Paris | 4043cde | 2012-01-03 14:23:08 -0500 | [diff] [blame] | 193 | *empty = 1; |
Al Viro | 94b5d26 | 2015-02-22 19:38:03 -0500 | [diff] [blame] | 194 | if (!(flags & LOOKUP_EMPTY)) { |
| 195 | putname(result); |
| 196 | return ERR_PTR(-ENOENT); |
| 197 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | } |
Linus Torvalds | 3f9f0aa | 2012-04-28 14:38:32 -0700 | [diff] [blame] | 199 | |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 200 | result->uptr = filename; |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 201 | result->aname = NULL; |
Jeff Layton | 7950e38 | 2012-10-10 16:43:13 -0400 | [diff] [blame] | 202 | audit_getname(result); |
| 203 | return result; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | } |
| 205 | |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 206 | struct filename * |
| 207 | getname(const char __user * filename) |
Al Viro | f52e0c1 | 2011-03-14 18:56:51 -0400 | [diff] [blame] | 208 | { |
Linus Torvalds | f7493e5 | 2012-03-22 16:10:40 -0700 | [diff] [blame] | 209 | return getname_flags(filename, 0, NULL); |
Al Viro | f52e0c1 | 2011-03-14 18:56:51 -0400 | [diff] [blame] | 210 | } |
| 211 | |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 212 | struct filename * |
| 213 | getname_kernel(const char * filename) |
| 214 | { |
| 215 | struct filename *result; |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 216 | int len = strlen(filename) + 1; |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 217 | |
| 218 | result = __getname(); |
| 219 | if (unlikely(!result)) |
| 220 | return ERR_PTR(-ENOMEM); |
| 221 | |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 222 | if (len <= EMBEDDED_NAME_MAX) { |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 223 | result->name = (char *)result->iname; |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 224 | } else if (len <= PATH_MAX) { |
Al Viro | 30ce4d1 | 2018-04-08 11:57:10 -0400 | [diff] [blame] | 225 | const size_t size = offsetof(struct filename, iname[1]); |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 226 | struct filename *tmp; |
| 227 | |
Al Viro | 30ce4d1 | 2018-04-08 11:57:10 -0400 | [diff] [blame] | 228 | tmp = kmalloc(size, GFP_KERNEL); |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 229 | if (unlikely(!tmp)) { |
| 230 | __putname(result); |
| 231 | return ERR_PTR(-ENOMEM); |
| 232 | } |
| 233 | tmp->name = (char *)result; |
Paul Moore | 0851854 | 2015-01-21 23:59:56 -0500 | [diff] [blame] | 234 | result = tmp; |
| 235 | } else { |
| 236 | __putname(result); |
| 237 | return ERR_PTR(-ENAMETOOLONG); |
| 238 | } |
| 239 | memcpy((char *)result->name, filename, len); |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 240 | result->uptr = NULL; |
| 241 | result->aname = NULL; |
Paul Moore | 55422d0 | 2015-01-22 00:00:23 -0500 | [diff] [blame] | 242 | result->refcnt = 1; |
Paul Moore | fd3522f | 2015-01-22 00:00:10 -0500 | [diff] [blame] | 243 | audit_getname(result); |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 244 | |
Linus Torvalds | c4ad8f9 | 2014-02-05 12:54:53 -0800 | [diff] [blame] | 245 | return result; |
| 246 | } |
| 247 | |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 248 | void putname(struct filename *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | { |
Paul Moore | 55422d0 | 2015-01-22 00:00:23 -0500 | [diff] [blame] | 250 | BUG_ON(name->refcnt <= 0); |
| 251 | |
| 252 | if (--name->refcnt > 0) |
| 253 | return; |
| 254 | |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 255 | if (name->name != name->iname) { |
Paul Moore | 55422d0 | 2015-01-22 00:00:23 -0500 | [diff] [blame] | 256 | __putname(name->name); |
| 257 | kfree(name); |
| 258 | } else |
| 259 | __putname(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 261 | |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 262 | static int check_acl(struct inode *inode, int mask) |
| 263 | { |
Linus Torvalds | 84635d6 | 2011-07-25 22:47:03 -0700 | [diff] [blame] | 264 | #ifdef CONFIG_FS_POSIX_ACL |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 265 | struct posix_acl *acl; |
| 266 | |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 267 | if (mask & MAY_NOT_BLOCK) { |
Al Viro | 3567866 | 2011-08-02 21:32:13 -0400 | [diff] [blame] | 268 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
| 269 | if (!acl) |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 270 | return -EAGAIN; |
Al Viro | 3567866 | 2011-08-02 21:32:13 -0400 | [diff] [blame] | 271 | /* no ->get_acl() calls in RCU mode... */ |
Andreas Gruenbacher | b8a7a3a | 2016-03-24 14:38:37 +0100 | [diff] [blame] | 272 | if (is_uncached_acl(acl)) |
Al Viro | 3567866 | 2011-08-02 21:32:13 -0400 | [diff] [blame] | 273 | return -ECHILD; |
Ari Savolainen | 206b1d0 | 2011-08-06 19:43:07 +0300 | [diff] [blame] | 274 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 275 | } |
| 276 | |
Christoph Hellwig | 2982baa | 2013-12-20 05:16:38 -0800 | [diff] [blame] | 277 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
| 278 | if (IS_ERR(acl)) |
| 279 | return PTR_ERR(acl); |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 280 | if (acl) { |
| 281 | int error = posix_acl_permission(inode, acl, mask); |
| 282 | posix_acl_release(acl); |
| 283 | return error; |
| 284 | } |
Linus Torvalds | 84635d6 | 2011-07-25 22:47:03 -0700 | [diff] [blame] | 285 | #endif |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 286 | |
| 287 | return -EAGAIN; |
| 288 | } |
| 289 | |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 290 | /* |
Andreas Gruenbacher | 948409c | 2011-10-23 23:13:33 +0530 | [diff] [blame] | 291 | * This does the basic permission checking |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 292 | */ |
Al Viro | 7e40145 | 2011-06-20 19:12:17 -0400 | [diff] [blame] | 293 | static int acl_permission_check(struct inode *inode, int mask) |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 294 | { |
Linus Torvalds | 26cf46b | 2011-05-13 11:51:01 -0700 | [diff] [blame] | 295 | unsigned int mode = inode->i_mode; |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 296 | |
Eric W. Biederman | 8e96e3b | 2012-03-03 21:17:15 -0800 | [diff] [blame] | 297 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 298 | mode >>= 6; |
| 299 | else { |
Linus Torvalds | e77819e | 2011-07-22 19:30:19 -0700 | [diff] [blame] | 300 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
Al Viro | 7e40145 | 2011-06-20 19:12:17 -0400 | [diff] [blame] | 301 | int error = check_acl(inode, mask); |
Nick Piggin | b74c79e | 2011-01-07 17:49:58 +1100 | [diff] [blame] | 302 | if (error != -EAGAIN) |
| 303 | return error; |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 304 | } |
| 305 | |
| 306 | if (in_group_p(inode->i_gid)) |
| 307 | mode >>= 3; |
| 308 | } |
| 309 | |
| 310 | /* |
| 311 | * If the DACs are ok we don't need any capability check. |
| 312 | */ |
Al Viro | 9c2c703 | 2011-06-20 19:06:22 -0400 | [diff] [blame] | 313 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 314 | return 0; |
| 315 | return -EACCES; |
| 316 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 317 | |
| 318 | /** |
Nick Piggin | b74c79e | 2011-01-07 17:49:58 +1100 | [diff] [blame] | 319 | * generic_permission - check for access rights on a Posix-like filesystem |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 320 | * @inode: inode to check access rights for |
Andreas Gruenbacher | 8fd90c8 | 2011-10-23 23:13:30 +0530 | [diff] [blame] | 321 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 322 | * |
| 323 | * Used to check for read/write/execute permissions on a file. |
| 324 | * We use "fsuid" for this, letting us set arbitrary permissions |
| 325 | * for filesystem access without changing the "normal" uids which |
Nick Piggin | b74c79e | 2011-01-07 17:49:58 +1100 | [diff] [blame] | 326 | * are used for other things. |
| 327 | * |
| 328 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk |
| 329 | * request cannot be satisfied (eg. requires blocking or too much complexity). |
| 330 | * It would then be called again in ref-walk mode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 331 | */ |
Al Viro | 2830ba7 | 2011-06-20 19:16:29 -0400 | [diff] [blame] | 332 | int generic_permission(struct inode *inode, int mask) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 333 | { |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 334 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 335 | |
| 336 | /* |
Andreas Gruenbacher | 948409c | 2011-10-23 23:13:33 +0530 | [diff] [blame] | 337 | * Do the basic permission checks. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | */ |
Al Viro | 7e40145 | 2011-06-20 19:12:17 -0400 | [diff] [blame] | 339 | ret = acl_permission_check(inode, mask); |
Linus Torvalds | 5909ccaa | 2009-08-28 11:51:25 -0700 | [diff] [blame] | 340 | if (ret != -EACCES) |
| 341 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 342 | |
Al Viro | d594e7e | 2011-06-20 19:55:42 -0400 | [diff] [blame] | 343 | if (S_ISDIR(inode->i_mode)) { |
| 344 | /* DACs are overridable for directories */ |
Al Viro | d594e7e | 2011-06-20 19:55:42 -0400 | [diff] [blame] | 345 | if (!(mask & MAY_WRITE)) |
Andy Lutomirski | 23adbe1 | 2014-06-10 12:45:42 -0700 | [diff] [blame] | 346 | if (capable_wrt_inode_uidgid(inode, |
| 347 | CAP_DAC_READ_SEARCH)) |
Al Viro | d594e7e | 2011-06-20 19:55:42 -0400 | [diff] [blame] | 348 | return 0; |
Andy Lutomirski | 23adbe1 | 2014-06-10 12:45:42 -0700 | [diff] [blame] | 349 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 350 | return 0; |
Stephen Smalley | 2a4c224 | 2017-03-10 12:14:18 -0500 | [diff] [blame] | 351 | return -EACCES; |
| 352 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 353 | |
| 354 | /* |
| 355 | * Searching includes executable on directories, else just read. |
| 356 | */ |
Serge E. Hallyn | 7ea6600 | 2009-12-29 14:50:19 -0600 | [diff] [blame] | 357 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
Al Viro | d594e7e | 2011-06-20 19:55:42 -0400 | [diff] [blame] | 358 | if (mask == MAY_READ) |
Andy Lutomirski | 23adbe1 | 2014-06-10 12:45:42 -0700 | [diff] [blame] | 359 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 360 | return 0; |
Stephen Smalley | 2a4c224 | 2017-03-10 12:14:18 -0500 | [diff] [blame] | 361 | /* |
| 362 | * Read/write DACs are always overridable. |
| 363 | * Executable DACs are overridable when there is |
| 364 | * at least one exec bit set. |
| 365 | */ |
| 366 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
| 367 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
| 368 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 369 | |
| 370 | return -EACCES; |
| 371 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 372 | EXPORT_SYMBOL(generic_permission); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 373 | |
Linus Torvalds | 3ddcd05 | 2011-08-06 22:45:50 -0700 | [diff] [blame] | 374 | /* |
| 375 | * We _really_ want to just do "generic_permission()" without |
| 376 | * even looking at the inode->i_op values. So we keep a cache |
| 377 | * flag in inode->i_opflags, that says "this has not special |
| 378 | * permission function, use the fast case". |
| 379 | */ |
| 380 | static inline int do_inode_permission(struct inode *inode, int mask) |
| 381 | { |
| 382 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { |
| 383 | if (likely(inode->i_op->permission)) |
| 384 | return inode->i_op->permission(inode, mask); |
| 385 | |
| 386 | /* This gets set once for the inode lifetime */ |
| 387 | spin_lock(&inode->i_lock); |
| 388 | inode->i_opflags |= IOP_FASTPERM; |
| 389 | spin_unlock(&inode->i_lock); |
| 390 | } |
| 391 | return generic_permission(inode, mask); |
| 392 | } |
| 393 | |
Christoph Hellwig | cb23beb | 2008-10-24 09:59:29 +0200 | [diff] [blame] | 394 | /** |
David Howells | 0bdaea9 | 2012-06-25 12:55:46 +0100 | [diff] [blame] | 395 | * sb_permission - Check superblock-level permissions |
| 396 | * @sb: Superblock of inode to check permission on |
Randy Dunlap | 5585263 | 2012-08-18 17:39:25 -0700 | [diff] [blame] | 397 | * @inode: Inode to check permission on |
David Howells | 0bdaea9 | 2012-06-25 12:55:46 +0100 | [diff] [blame] | 398 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
| 399 | * |
| 400 | * Separate out file-system wide checks from inode-specific permission checks. |
| 401 | */ |
| 402 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) |
| 403 | { |
| 404 | if (unlikely(mask & MAY_WRITE)) { |
| 405 | umode_t mode = inode->i_mode; |
| 406 | |
| 407 | /* Nobody gets write access to a read-only fs. */ |
David Howells | bc98a42 | 2017-07-17 08:45:34 +0100 | [diff] [blame] | 408 | if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) |
David Howells | 0bdaea9 | 2012-06-25 12:55:46 +0100 | [diff] [blame] | 409 | return -EROFS; |
| 410 | } |
| 411 | return 0; |
| 412 | } |
| 413 | |
| 414 | /** |
| 415 | * inode_permission - Check for access rights to a given inode |
| 416 | * @inode: Inode to check permission on |
| 417 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
| 418 | * |
| 419 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for |
| 420 | * this, letting us set arbitrary permissions for filesystem access without |
| 421 | * changing the "normal" UIDs which are used for other things. |
| 422 | * |
| 423 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. |
| 424 | */ |
| 425 | int inode_permission(struct inode *inode, int mask) |
| 426 | { |
| 427 | int retval; |
| 428 | |
| 429 | retval = sb_permission(inode->i_sb, inode, mask); |
| 430 | if (retval) |
| 431 | return retval; |
Eric Biggers | 4bfd054 | 2018-01-16 21:44:24 -0800 | [diff] [blame] | 432 | |
| 433 | if (unlikely(mask & MAY_WRITE)) { |
| 434 | /* |
| 435 | * Nobody gets write access to an immutable file. |
| 436 | */ |
| 437 | if (IS_IMMUTABLE(inode)) |
| 438 | return -EPERM; |
| 439 | |
| 440 | /* |
| 441 | * Updating mtime will likely cause i_uid and i_gid to be |
| 442 | * written back improperly if their true value is unknown |
| 443 | * to the vfs. |
| 444 | */ |
| 445 | if (HAS_UNMAPPED_ID(inode)) |
| 446 | return -EACCES; |
| 447 | } |
| 448 | |
| 449 | retval = do_inode_permission(inode, mask); |
| 450 | if (retval) |
| 451 | return retval; |
| 452 | |
| 453 | retval = devcgroup_inode_permission(inode, mask); |
| 454 | if (retval) |
| 455 | return retval; |
| 456 | |
| 457 | return security_inode_permission(inode, mask); |
David Howells | 0bdaea9 | 2012-06-25 12:55:46 +0100 | [diff] [blame] | 458 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 459 | EXPORT_SYMBOL(inode_permission); |
David Howells | 0bdaea9 | 2012-06-25 12:55:46 +0100 | [diff] [blame] | 460 | |
| 461 | /** |
Jan Blunck | 5dd784d0 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 462 | * path_get - get a reference to a path |
| 463 | * @path: path to get the reference to |
| 464 | * |
| 465 | * Given a path increment the reference count to the dentry and the vfsmount. |
| 466 | */ |
Al Viro | dcf787f | 2013-03-01 23:51:07 -0500 | [diff] [blame] | 467 | void path_get(const struct path *path) |
Jan Blunck | 5dd784d0 | 2008-02-14 19:34:38 -0800 | [diff] [blame] | 468 | { |
| 469 | mntget(path->mnt); |
| 470 | dget(path->dentry); |
| 471 | } |
| 472 | EXPORT_SYMBOL(path_get); |
| 473 | |
| 474 | /** |
Jan Blunck | 1d957f9 | 2008-02-14 19:34:35 -0800 | [diff] [blame] | 475 | * path_put - put a reference to a path |
| 476 | * @path: path to put the reference to |
| 477 | * |
| 478 | * Given a path decrement the reference count to the dentry and the vfsmount. |
| 479 | */ |
Al Viro | dcf787f | 2013-03-01 23:51:07 -0500 | [diff] [blame] | 480 | void path_put(const struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 481 | { |
Jan Blunck | 1d957f9 | 2008-02-14 19:34:35 -0800 | [diff] [blame] | 482 | dput(path->dentry); |
| 483 | mntput(path->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 484 | } |
Jan Blunck | 1d957f9 | 2008-02-14 19:34:35 -0800 | [diff] [blame] | 485 | EXPORT_SYMBOL(path_put); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 486 | |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 487 | #define EMBEDDED_LEVELS 2 |
Al Viro | 1f55a6e | 2014-11-01 19:30:41 -0400 | [diff] [blame] | 488 | struct nameidata { |
| 489 | struct path path; |
Al Viro | 1cf2665 | 2015-05-06 16:01:56 -0400 | [diff] [blame] | 490 | struct qstr last; |
Al Viro | 1f55a6e | 2014-11-01 19:30:41 -0400 | [diff] [blame] | 491 | struct path root; |
| 492 | struct inode *inode; /* path.dentry.d_inode */ |
| 493 | unsigned int flags; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 494 | unsigned seq, m_seq; |
Al Viro | 1f55a6e | 2014-11-01 19:30:41 -0400 | [diff] [blame] | 495 | int last_type; |
| 496 | unsigned depth; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 497 | int total_link_count; |
Al Viro | 697fc6c | 2015-05-02 19:38:35 -0400 | [diff] [blame] | 498 | struct saved { |
| 499 | struct path link; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 500 | struct delayed_call done; |
Al Viro | 697fc6c | 2015-05-02 19:38:35 -0400 | [diff] [blame] | 501 | const char *name; |
Al Viro | 0450b2d | 2015-05-08 13:23:53 -0400 | [diff] [blame] | 502 | unsigned seq; |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 503 | } *stack, internal[EMBEDDED_LEVELS]; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 504 | struct filename *name; |
| 505 | struct nameidata *saved; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 506 | struct inode *link_inode; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 507 | unsigned root_seq; |
| 508 | int dfd; |
Kees Cook | 3859a27 | 2016-10-28 01:22:25 -0700 | [diff] [blame] | 509 | } __randomize_layout; |
Al Viro | 1f55a6e | 2014-11-01 19:30:41 -0400 | [diff] [blame] | 510 | |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 511 | static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 512 | { |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 513 | struct nameidata *old = current->nameidata; |
| 514 | p->stack = p->internal; |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 515 | p->dfd = dfd; |
| 516 | p->name = name; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 517 | p->total_link_count = old ? old->total_link_count : 0; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 518 | p->saved = old; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 519 | current->nameidata = p; |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 520 | } |
| 521 | |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 522 | static void restore_nameidata(void) |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 523 | { |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 524 | struct nameidata *now = current->nameidata, *old = now->saved; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 525 | |
| 526 | current->nameidata = old; |
| 527 | if (old) |
| 528 | old->total_link_count = now->total_link_count; |
Al Viro | e1a63bb | 2015-12-05 21:06:33 -0500 | [diff] [blame] | 529 | if (now->stack != now->internal) |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 530 | kfree(now->stack); |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 531 | } |
| 532 | |
| 533 | static int __nd_alloc_stack(struct nameidata *nd) |
| 534 | { |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 535 | struct saved *p; |
| 536 | |
| 537 | if (nd->flags & LOOKUP_RCU) { |
Kees Cook | 6da2ec5 | 2018-06-12 13:55:00 -0700 | [diff] [blame] | 538 | p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 539 | GFP_ATOMIC); |
| 540 | if (unlikely(!p)) |
| 541 | return -ECHILD; |
| 542 | } else { |
Kees Cook | 6da2ec5 | 2018-06-12 13:55:00 -0700 | [diff] [blame] | 543 | p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved), |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 544 | GFP_KERNEL); |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 545 | if (unlikely(!p)) |
| 546 | return -ENOMEM; |
| 547 | } |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 548 | memcpy(p, nd->internal, sizeof(nd->internal)); |
| 549 | nd->stack = p; |
| 550 | return 0; |
| 551 | } |
| 552 | |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 553 | /** |
| 554 | * path_connected - Verify that a path->dentry is below path->mnt.mnt_root |
| 555 | * @path: nameidate to verify |
| 556 | * |
| 557 | * Rename can sometimes move a file or directory outside of a bind |
| 558 | * mount, path_connected allows those cases to be detected. |
| 559 | */ |
| 560 | static bool path_connected(const struct path *path) |
| 561 | { |
| 562 | struct vfsmount *mnt = path->mnt; |
Eric W. Biederman | 95dd775 | 2018-03-14 18:20:29 -0500 | [diff] [blame] | 563 | struct super_block *sb = mnt->mnt_sb; |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 564 | |
Eric W. Biederman | 95dd775 | 2018-03-14 18:20:29 -0500 | [diff] [blame] | 565 | /* Bind mounts and multi-root filesystems can have disconnected paths */ |
| 566 | if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root)) |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 567 | return true; |
| 568 | |
| 569 | return is_subdir(path->dentry, mnt->mnt_root); |
| 570 | } |
| 571 | |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 572 | static inline int nd_alloc_stack(struct nameidata *nd) |
| 573 | { |
Al Viro | da4e0be | 2015-05-03 20:52:15 -0400 | [diff] [blame] | 574 | if (likely(nd->depth != EMBEDDED_LEVELS)) |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 575 | return 0; |
| 576 | if (likely(nd->stack != nd->internal)) |
| 577 | return 0; |
| 578 | return __nd_alloc_stack(nd); |
| 579 | } |
| 580 | |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 581 | static void drop_links(struct nameidata *nd) |
| 582 | { |
| 583 | int i = nd->depth; |
| 584 | while (i--) { |
| 585 | struct saved *last = nd->stack + i; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 586 | do_delayed_call(&last->done); |
| 587 | clear_delayed_call(&last->done); |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 588 | } |
| 589 | } |
| 590 | |
| 591 | static void terminate_walk(struct nameidata *nd) |
| 592 | { |
| 593 | drop_links(nd); |
| 594 | if (!(nd->flags & LOOKUP_RCU)) { |
| 595 | int i; |
| 596 | path_put(&nd->path); |
| 597 | for (i = 0; i < nd->depth; i++) |
| 598 | path_put(&nd->stack[i].link); |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 599 | if (nd->flags & LOOKUP_ROOT_GRABBED) { |
Al Viro | 102b8af | 2015-05-12 17:35:52 -0400 | [diff] [blame] | 600 | path_put(&nd->root); |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 601 | nd->flags &= ~LOOKUP_ROOT_GRABBED; |
Al Viro | 102b8af | 2015-05-12 17:35:52 -0400 | [diff] [blame] | 602 | } |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 603 | } else { |
| 604 | nd->flags &= ~LOOKUP_RCU; |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 605 | rcu_read_unlock(); |
| 606 | } |
| 607 | nd->depth = 0; |
| 608 | } |
| 609 | |
| 610 | /* path_put is needed afterwards regardless of success or failure */ |
| 611 | static bool legitimize_path(struct nameidata *nd, |
| 612 | struct path *path, unsigned seq) |
| 613 | { |
| 614 | int res = __legitimize_mnt(path->mnt, nd->m_seq); |
| 615 | if (unlikely(res)) { |
| 616 | if (res > 0) |
| 617 | path->mnt = NULL; |
| 618 | path->dentry = NULL; |
| 619 | return false; |
| 620 | } |
| 621 | if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { |
| 622 | path->dentry = NULL; |
| 623 | return false; |
| 624 | } |
| 625 | return !read_seqcount_retry(&path->dentry->d_seq, seq); |
| 626 | } |
| 627 | |
| 628 | static bool legitimize_links(struct nameidata *nd) |
| 629 | { |
| 630 | int i; |
| 631 | for (i = 0; i < nd->depth; i++) { |
| 632 | struct saved *last = nd->stack + i; |
| 633 | if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { |
| 634 | drop_links(nd); |
| 635 | nd->depth = i + 1; |
| 636 | return false; |
| 637 | } |
| 638 | } |
| 639 | return true; |
| 640 | } |
| 641 | |
Al Viro | ee594bf | 2019-07-16 21:05:36 -0400 | [diff] [blame] | 642 | static bool legitimize_root(struct nameidata *nd) |
| 643 | { |
| 644 | if (!nd->root.mnt || (nd->flags & LOOKUP_ROOT)) |
| 645 | return true; |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 646 | nd->flags |= LOOKUP_ROOT_GRABBED; |
Al Viro | ee594bf | 2019-07-16 21:05:36 -0400 | [diff] [blame] | 647 | return legitimize_path(nd, &nd->root, nd->root_seq); |
| 648 | } |
| 649 | |
Al Viro | 19660af | 2011-03-25 10:32:48 -0400 | [diff] [blame] | 650 | /* |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 651 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
Al Viro | 19660af | 2011-03-25 10:32:48 -0400 | [diff] [blame] | 652 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
| 653 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab |
Mike Marshall | 57e3715 | 2015-11-30 11:11:59 -0500 | [diff] [blame] | 654 | * normal reference counts on dentries and vfsmounts to transition to ref-walk |
Al Viro | 19660af | 2011-03-25 10:32:48 -0400 | [diff] [blame] | 655 | * mode. Refcounts are grabbed at the last known good point before rcu-walk |
| 656 | * got stuck, so ref-walk may continue from there. If this is not successful |
| 657 | * (eg. a seqcount has changed), then failure is returned and it's up to caller |
| 658 | * to restart the path walk from the beginning in ref-walk mode. |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 659 | */ |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 660 | |
| 661 | /** |
Al Viro | 19660af | 2011-03-25 10:32:48 -0400 | [diff] [blame] | 662 | * unlazy_walk - try to switch to ref-walk mode. |
| 663 | * @nd: nameidata pathwalk data |
Randy Dunlap | 3919162 | 2011-01-08 19:36:21 -0800 | [diff] [blame] | 664 | * Returns: 0 on success, -ECHILD on failure |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 665 | * |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 666 | * unlazy_walk attempts to legitimize the current nd->path and nd->root |
| 667 | * for ref-walk mode. |
| 668 | * Must be called from rcu-walk context. |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 669 | * Nothing should touch nameidata between unlazy_walk() failure and |
| 670 | * terminate_walk(). |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 671 | */ |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 672 | static int unlazy_walk(struct nameidata *nd) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 673 | { |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 674 | struct dentry *parent = nd->path.dentry; |
| 675 | |
| 676 | BUG_ON(!(nd->flags & LOOKUP_RCU)); |
Linus Torvalds | e5c832d | 2013-09-08 18:13:49 -0700 | [diff] [blame] | 677 | |
Linus Torvalds | e5c832d | 2013-09-08 18:13:49 -0700 | [diff] [blame] | 678 | nd->flags &= ~LOOKUP_RCU; |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 679 | if (unlikely(!legitimize_links(nd))) |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 680 | goto out1; |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 681 | if (unlikely(!legitimize_path(nd, &nd->path, nd->seq))) |
| 682 | goto out; |
Al Viro | ee594bf | 2019-07-16 21:05:36 -0400 | [diff] [blame] | 683 | if (unlikely(!legitimize_root(nd))) |
| 684 | goto out; |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 685 | rcu_read_unlock(); |
| 686 | BUG_ON(nd->inode != parent->d_inode); |
| 687 | return 0; |
| 688 | |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 689 | out1: |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 690 | nd->path.mnt = NULL; |
| 691 | nd->path.dentry = NULL; |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 692 | out: |
| 693 | rcu_read_unlock(); |
| 694 | return -ECHILD; |
| 695 | } |
| 696 | |
| 697 | /** |
| 698 | * unlazy_child - try to switch to ref-walk mode. |
| 699 | * @nd: nameidata pathwalk data |
| 700 | * @dentry: child of nd->path.dentry |
| 701 | * @seq: seq number to check dentry against |
| 702 | * Returns: 0 on success, -ECHILD on failure |
| 703 | * |
| 704 | * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry |
| 705 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on |
| 706 | * @nd. Must be called from rcu-walk context. |
| 707 | * Nothing should touch nameidata between unlazy_child() failure and |
| 708 | * terminate_walk(). |
| 709 | */ |
| 710 | static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq) |
| 711 | { |
| 712 | BUG_ON(!(nd->flags & LOOKUP_RCU)); |
| 713 | |
| 714 | nd->flags &= ~LOOKUP_RCU; |
| 715 | if (unlikely(!legitimize_links(nd))) |
| 716 | goto out2; |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 717 | if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) |
| 718 | goto out2; |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 719 | if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref))) |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 720 | goto out1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 721 | |
Linus Torvalds | 1557008 | 2013-09-02 11:38:06 -0700 | [diff] [blame] | 722 | /* |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 723 | * We need to move both the parent and the dentry from the RCU domain |
| 724 | * to be properly refcounted. And the sequence number in the dentry |
| 725 | * validates *both* dentry counters, since we checked the sequence |
| 726 | * number of the parent after we got the child sequence number. So we |
| 727 | * know the parent must still be valid if the child sequence number is |
Linus Torvalds | 1557008 | 2013-09-02 11:38:06 -0700 | [diff] [blame] | 728 | */ |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 729 | if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) |
| 730 | goto out; |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 731 | if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) |
| 732 | goto out_dput; |
Linus Torvalds | e5c832d | 2013-09-08 18:13:49 -0700 | [diff] [blame] | 733 | /* |
| 734 | * Sequence counts matched. Now make sure that the root is |
| 735 | * still valid and get it if required. |
| 736 | */ |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 737 | if (unlikely(!legitimize_root(nd))) |
| 738 | goto out_dput; |
Al Viro | 8b61e74 | 2013-11-08 12:45:01 -0500 | [diff] [blame] | 739 | rcu_read_unlock(); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 740 | return 0; |
Al Viro | 19660af | 2011-03-25 10:32:48 -0400 | [diff] [blame] | 741 | |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 742 | out2: |
| 743 | nd->path.mnt = NULL; |
| 744 | out1: |
| 745 | nd->path.dentry = NULL; |
Linus Torvalds | e5c832d | 2013-09-08 18:13:49 -0700 | [diff] [blame] | 746 | out: |
Al Viro | 8b61e74 | 2013-11-08 12:45:01 -0500 | [diff] [blame] | 747 | rcu_read_unlock(); |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 748 | return -ECHILD; |
| 749 | out_dput: |
| 750 | rcu_read_unlock(); |
| 751 | dput(dentry); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 752 | return -ECHILD; |
| 753 | } |
| 754 | |
Al Viro | 4ce16ef3 | 2012-06-10 16:10:59 -0400 | [diff] [blame] | 755 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
Nick Piggin | 34286d6 | 2011-01-07 17:49:57 +1100 | [diff] [blame] | 756 | { |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 757 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) |
| 758 | return dentry->d_op->d_revalidate(dentry, flags); |
| 759 | else |
| 760 | return 1; |
Nick Piggin | 34286d6 | 2011-01-07 17:49:57 +1100 | [diff] [blame] | 761 | } |
| 762 | |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 763 | /** |
| 764 | * complete_walk - successful completion of path walk |
| 765 | * @nd: pointer nameidata |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 766 | * |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 767 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
| 768 | * Revalidate the final result, unless we'd already done that during |
| 769 | * the path walk or the filesystem doesn't ask for it. Return 0 on |
| 770 | * success, -error on failure. In case of failure caller does not |
| 771 | * need to drop nd->path. |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 772 | */ |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 773 | static int complete_walk(struct nameidata *nd) |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 774 | { |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 775 | struct dentry *dentry = nd->path.dentry; |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 776 | int status; |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 777 | |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 778 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 779 | if (!(nd->flags & LOOKUP_ROOT)) |
| 780 | nd->root.mnt = NULL; |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 781 | if (unlikely(unlazy_walk(nd))) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 782 | return -ECHILD; |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 783 | } |
| 784 | |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 785 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 786 | return 0; |
| 787 | |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 788 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 789 | return 0; |
| 790 | |
Jeff Layton | ecf3d1f | 2013-02-20 11:19:05 -0500 | [diff] [blame] | 791 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 792 | if (status > 0) |
| 793 | return 0; |
| 794 | |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 795 | if (!status) |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 796 | status = -ESTALE; |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 797 | |
Jeff Layton | 39159de | 2009-12-07 12:01:50 -0500 | [diff] [blame] | 798 | return status; |
| 799 | } |
| 800 | |
Al Viro | 18d8c86 | 2015-05-12 16:32:34 -0400 | [diff] [blame] | 801 | static void set_root(struct nameidata *nd) |
Al Viro | 2a73787 | 2009-04-07 11:49:53 -0400 | [diff] [blame] | 802 | { |
Al Viro | 7bd8837 | 2014-09-13 21:55:46 -0400 | [diff] [blame] | 803 | struct fs_struct *fs = current->fs; |
Nick Piggin | c28cc36 | 2011-01-07 17:49:53 +1100 | [diff] [blame] | 804 | |
Al Viro | 9e6697e | 2015-12-05 20:07:21 -0500 | [diff] [blame] | 805 | if (nd->flags & LOOKUP_RCU) { |
| 806 | unsigned seq; |
| 807 | |
| 808 | do { |
| 809 | seq = read_seqcount_begin(&fs->seq); |
| 810 | nd->root = fs->root; |
| 811 | nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
| 812 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 813 | } else { |
| 814 | get_fs_root(fs, &nd->root); |
Al Viro | 84a2bd3 | 2019-07-16 21:20:17 -0400 | [diff] [blame] | 815 | nd->flags |= LOOKUP_ROOT_GRABBED; |
Al Viro | 9e6697e | 2015-12-05 20:07:21 -0500 | [diff] [blame] | 816 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 817 | } |
| 818 | |
Jan Blunck | 1d957f9 | 2008-02-14 19:34:35 -0800 | [diff] [blame] | 819 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
Miklos Szeredi | 09dd17d | 2005-09-06 15:18:21 -0700 | [diff] [blame] | 820 | { |
| 821 | dput(path->dentry); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 822 | if (path->mnt != nd->path.mnt) |
Miklos Szeredi | 09dd17d | 2005-09-06 15:18:21 -0700 | [diff] [blame] | 823 | mntput(path->mnt); |
| 824 | } |
| 825 | |
Nick Piggin | 7b9337a | 2011-01-14 08:42:43 +0000 | [diff] [blame] | 826 | static inline void path_to_nameidata(const struct path *path, |
| 827 | struct nameidata *nd) |
Miklos Szeredi | 09dd17d | 2005-09-06 15:18:21 -0700 | [diff] [blame] | 828 | { |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 829 | if (!(nd->flags & LOOKUP_RCU)) { |
| 830 | dput(nd->path.dentry); |
| 831 | if (nd->path.mnt != path->mnt) |
| 832 | mntput(nd->path.mnt); |
Huang Shijie | 9a22968 | 2010-04-02 17:37:13 +0800 | [diff] [blame] | 833 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 834 | nd->path.mnt = path->mnt; |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 835 | nd->path.dentry = path->dentry; |
Miklos Szeredi | 09dd17d | 2005-09-06 15:18:21 -0700 | [diff] [blame] | 836 | } |
| 837 | |
Al Viro | 248fb5b | 2015-12-05 20:51:58 -0500 | [diff] [blame] | 838 | static int nd_jump_root(struct nameidata *nd) |
| 839 | { |
| 840 | if (nd->flags & LOOKUP_RCU) { |
| 841 | struct dentry *d; |
| 842 | nd->path = nd->root; |
| 843 | d = nd->path.dentry; |
| 844 | nd->inode = d->d_inode; |
| 845 | nd->seq = nd->root_seq; |
| 846 | if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) |
| 847 | return -ECHILD; |
| 848 | } else { |
| 849 | path_put(&nd->path); |
| 850 | nd->path = nd->root; |
| 851 | path_get(&nd->path); |
| 852 | nd->inode = nd->path.dentry->d_inode; |
| 853 | } |
| 854 | nd->flags |= LOOKUP_JUMPED; |
| 855 | return 0; |
| 856 | } |
| 857 | |
Christoph Hellwig | b5fb63c1 | 2012-06-18 10:47:04 -0400 | [diff] [blame] | 858 | /* |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 859 | * Helper to directly jump to a known parsed path from ->get_link, |
Christoph Hellwig | b5fb63c1 | 2012-06-18 10:47:04 -0400 | [diff] [blame] | 860 | * caller must have taken a reference to path beforehand. |
| 861 | */ |
Al Viro | 6e77137b | 2015-05-02 13:37:52 -0400 | [diff] [blame] | 862 | void nd_jump_link(struct path *path) |
Christoph Hellwig | b5fb63c1 | 2012-06-18 10:47:04 -0400 | [diff] [blame] | 863 | { |
Al Viro | 6e77137b | 2015-05-02 13:37:52 -0400 | [diff] [blame] | 864 | struct nameidata *nd = current->nameidata; |
Christoph Hellwig | b5fb63c1 | 2012-06-18 10:47:04 -0400 | [diff] [blame] | 865 | path_put(&nd->path); |
| 866 | |
| 867 | nd->path = *path; |
| 868 | nd->inode = nd->path.dentry->d_inode; |
| 869 | nd->flags |= LOOKUP_JUMPED; |
Christoph Hellwig | b5fb63c1 | 2012-06-18 10:47:04 -0400 | [diff] [blame] | 870 | } |
| 871 | |
Al Viro | b9ff442 | 2015-05-02 20:19:23 -0400 | [diff] [blame] | 872 | static inline void put_link(struct nameidata *nd) |
Al Viro | 574197e | 2011-03-14 22:20:34 -0400 | [diff] [blame] | 873 | { |
Al Viro | 21c3003 | 2015-05-03 21:06:24 -0400 | [diff] [blame] | 874 | struct saved *last = nd->stack + --nd->depth; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 875 | do_delayed_call(&last->done); |
Al Viro | 6548fae | 2015-05-07 20:32:22 -0400 | [diff] [blame] | 876 | if (!(nd->flags & LOOKUP_RCU)) |
| 877 | path_put(&last->link); |
Al Viro | 574197e | 2011-03-14 22:20:34 -0400 | [diff] [blame] | 878 | } |
| 879 | |
Linus Torvalds | 561ec64 | 2012-10-26 10:05:07 -0700 | [diff] [blame] | 880 | int sysctl_protected_symlinks __read_mostly = 0; |
| 881 | int sysctl_protected_hardlinks __read_mostly = 0; |
Salvatore Mesoraca | 30aba66 | 2018-08-23 17:00:35 -0700 | [diff] [blame] | 882 | int sysctl_protected_fifos __read_mostly; |
| 883 | int sysctl_protected_regular __read_mostly; |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 884 | |
| 885 | /** |
| 886 | * may_follow_link - Check symlink following for unsafe situations |
Randy Dunlap | 5585263 | 2012-08-18 17:39:25 -0700 | [diff] [blame] | 887 | * @nd: nameidata pathwalk data |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 888 | * |
| 889 | * In the case of the sysctl_protected_symlinks sysctl being enabled, |
| 890 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is |
| 891 | * in a sticky world-writable directory. This is to protect privileged |
| 892 | * processes from failing races against path names that may change out |
| 893 | * from under them by way of other users creating malicious symlinks. |
| 894 | * It will permit symlinks to be followed only when outside a sticky |
| 895 | * world-writable directory, or when the uid of the symlink and follower |
| 896 | * match, or when the directory owner matches the symlink's owner. |
| 897 | * |
| 898 | * Returns 0 if following the symlink is allowed, -ve on error. |
| 899 | */ |
Al Viro | fec2fa2 | 2015-05-06 15:58:18 -0400 | [diff] [blame] | 900 | static inline int may_follow_link(struct nameidata *nd) |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 901 | { |
| 902 | const struct inode *inode; |
| 903 | const struct inode *parent; |
Seth Forshee | 2d7f9e2 | 2016-04-26 14:36:23 -0500 | [diff] [blame] | 904 | kuid_t puid; |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 905 | |
| 906 | if (!sysctl_protected_symlinks) |
| 907 | return 0; |
| 908 | |
| 909 | /* Allowed if owner and follower match. */ |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 910 | inode = nd->link_inode; |
Eric W. Biederman | 81abe27 | 2012-08-03 09:38:08 -0700 | [diff] [blame] | 911 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 912 | return 0; |
| 913 | |
| 914 | /* Allowed if parent directory not sticky and world-writable. */ |
Al Viro | aa65fa3 | 2015-08-04 23:23:50 -0400 | [diff] [blame] | 915 | parent = nd->inode; |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 916 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) |
| 917 | return 0; |
| 918 | |
| 919 | /* Allowed if parent directory and link owner match. */ |
Seth Forshee | 2d7f9e2 | 2016-04-26 14:36:23 -0500 | [diff] [blame] | 920 | puid = parent->i_uid; |
| 921 | if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 922 | return 0; |
| 923 | |
Al Viro | 31956502 | 2015-05-07 20:37:40 -0400 | [diff] [blame] | 924 | if (nd->flags & LOOKUP_RCU) |
| 925 | return -ECHILD; |
| 926 | |
Richard Guy Briggs | ea841ba | 2018-03-21 04:42:21 -0400 | [diff] [blame] | 927 | audit_inode(nd->name, nd->stack[0].link.dentry, 0); |
Richard Guy Briggs | 94b9d9b | 2018-03-21 04:42:20 -0400 | [diff] [blame] | 928 | audit_log_link_denied("follow_link"); |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 929 | return -EACCES; |
| 930 | } |
| 931 | |
| 932 | /** |
| 933 | * safe_hardlink_source - Check for safe hardlink conditions |
| 934 | * @inode: the source inode to hardlink from |
| 935 | * |
| 936 | * Return false if at least one of the following conditions: |
| 937 | * - inode is not a regular file |
| 938 | * - inode is setuid |
| 939 | * - inode is setgid and group-exec |
| 940 | * - access failure for read and write |
| 941 | * |
| 942 | * Otherwise returns true. |
| 943 | */ |
| 944 | static bool safe_hardlink_source(struct inode *inode) |
| 945 | { |
| 946 | umode_t mode = inode->i_mode; |
| 947 | |
| 948 | /* Special files should not get pinned to the filesystem. */ |
| 949 | if (!S_ISREG(mode)) |
| 950 | return false; |
| 951 | |
| 952 | /* Setuid files should not get pinned to the filesystem. */ |
| 953 | if (mode & S_ISUID) |
| 954 | return false; |
| 955 | |
| 956 | /* Executable setgid files should not get pinned to the filesystem. */ |
| 957 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) |
| 958 | return false; |
| 959 | |
| 960 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ |
| 961 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) |
| 962 | return false; |
| 963 | |
| 964 | return true; |
| 965 | } |
| 966 | |
| 967 | /** |
| 968 | * may_linkat - Check permissions for creating a hardlink |
| 969 | * @link: the source to hardlink from |
| 970 | * |
| 971 | * Block hardlink when all of: |
| 972 | * - sysctl_protected_hardlinks enabled |
| 973 | * - fsuid does not match inode |
| 974 | * - hardlink source is unsafe (see safe_hardlink_source() above) |
Dirk Steinmetz | f2ca379 | 2015-10-20 16:09:19 +0200 | [diff] [blame] | 975 | * - not CAP_FOWNER in a namespace with the inode owner uid mapped |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 976 | * |
| 977 | * Returns 0 if successful, -ve on error. |
| 978 | */ |
| 979 | static int may_linkat(struct path *link) |
| 980 | { |
Eric W. Biederman | 593d1ce | 2017-09-14 12:07:32 -0500 | [diff] [blame] | 981 | struct inode *inode = link->dentry->d_inode; |
| 982 | |
| 983 | /* Inode writeback is not safe when the uid or gid are invalid. */ |
| 984 | if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) |
| 985 | return -EOVERFLOW; |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 986 | |
| 987 | if (!sysctl_protected_hardlinks) |
| 988 | return 0; |
| 989 | |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 990 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, |
| 991 | * otherwise, it must be a safe source. |
| 992 | */ |
Kees Cook | cc658db | 2017-06-21 09:53:06 -0700 | [diff] [blame] | 993 | if (safe_hardlink_source(inode) || inode_owner_or_capable(inode)) |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 994 | return 0; |
| 995 | |
Richard Guy Briggs | 94b9d9b | 2018-03-21 04:42:20 -0400 | [diff] [blame] | 996 | audit_log_link_denied("linkat"); |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 997 | return -EPERM; |
| 998 | } |
| 999 | |
Salvatore Mesoraca | 30aba66 | 2018-08-23 17:00:35 -0700 | [diff] [blame] | 1000 | /** |
| 1001 | * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory |
| 1002 | * should be allowed, or not, on files that already |
| 1003 | * exist. |
| 1004 | * @dir: the sticky parent directory |
| 1005 | * @inode: the inode of the file to open |
| 1006 | * |
| 1007 | * Block an O_CREAT open of a FIFO (or a regular file) when: |
| 1008 | * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled |
| 1009 | * - the file already exists |
| 1010 | * - we are in a sticky directory |
| 1011 | * - we don't own the file |
| 1012 | * - the owner of the directory doesn't own the file |
| 1013 | * - the directory is world writable |
| 1014 | * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2 |
| 1015 | * the directory doesn't have to be world writable: being group writable will |
| 1016 | * be enough. |
| 1017 | * |
| 1018 | * Returns 0 if the open is allowed, -ve on error. |
| 1019 | */ |
| 1020 | static int may_create_in_sticky(struct dentry * const dir, |
| 1021 | struct inode * const inode) |
| 1022 | { |
| 1023 | if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || |
| 1024 | (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || |
| 1025 | likely(!(dir->d_inode->i_mode & S_ISVTX)) || |
| 1026 | uid_eq(inode->i_uid, dir->d_inode->i_uid) || |
| 1027 | uid_eq(current_fsuid(), inode->i_uid)) |
| 1028 | return 0; |
| 1029 | |
| 1030 | if (likely(dir->d_inode->i_mode & 0002) || |
| 1031 | (dir->d_inode->i_mode & 0020 && |
| 1032 | ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || |
| 1033 | (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { |
| 1034 | return -EACCES; |
| 1035 | } |
| 1036 | return 0; |
| 1037 | } |
| 1038 | |
Al Viro | 3b2e7f7 | 2015-04-19 00:53:50 -0400 | [diff] [blame] | 1039 | static __always_inline |
| 1040 | const char *get_link(struct nameidata *nd) |
Ian Kent | 051d381 | 2006-03-27 01:14:53 -0800 | [diff] [blame] | 1041 | { |
Al Viro | ab10492 | 2015-05-10 11:50:01 -0400 | [diff] [blame] | 1042 | struct saved *last = nd->stack + nd->depth - 1; |
Al Viro | 1cf2665 | 2015-05-06 16:01:56 -0400 | [diff] [blame] | 1043 | struct dentry *dentry = last->link.dentry; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1044 | struct inode *inode = nd->link_inode; |
Al Viro | 6d7b5aa | 2012-06-10 04:15:17 -0400 | [diff] [blame] | 1045 | int error; |
Al Viro | 0a959df | 2015-04-18 18:23:41 -0400 | [diff] [blame] | 1046 | const char *res; |
Ian Kent | 051d381 | 2006-03-27 01:14:53 -0800 | [diff] [blame] | 1047 | |
NeilBrown | 8fa9dd2 | 2015-03-23 13:37:40 +1100 | [diff] [blame] | 1048 | if (!(nd->flags & LOOKUP_RCU)) { |
| 1049 | touch_atime(&last->link); |
| 1050 | cond_resched(); |
Miklos Szeredi | c671854 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 1051 | } else if (atime_needs_update(&last->link, inode)) { |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1052 | if (unlikely(unlazy_walk(nd))) |
NeilBrown | 8fa9dd2 | 2015-03-23 13:37:40 +1100 | [diff] [blame] | 1053 | return ERR_PTR(-ECHILD); |
| 1054 | touch_atime(&last->link); |
| 1055 | } |
| 1056 | |
NeilBrown | bda0be7 | 2015-03-23 13:37:39 +1100 | [diff] [blame] | 1057 | error = security_inode_follow_link(dentry, inode, |
| 1058 | nd->flags & LOOKUP_RCU); |
| 1059 | if (unlikely(error)) |
Al Viro | 6920a44 | 2015-05-10 10:43:46 -0400 | [diff] [blame] | 1060 | return ERR_PTR(error); |
Al Viro | 36f3b4f | 2011-02-22 21:24:38 -0500 | [diff] [blame] | 1061 | |
Al Viro | 86acdca1 | 2009-12-22 23:45:11 -0500 | [diff] [blame] | 1062 | nd->last_type = LAST_BIND; |
Eric Biggers | 4c4f7c1 | 2019-04-10 13:21:14 -0700 | [diff] [blame] | 1063 | res = READ_ONCE(inode->i_link); |
Al Viro | d4dee48 | 2015-04-30 20:08:02 -0400 | [diff] [blame] | 1064 | if (!res) { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1065 | const char * (*get)(struct dentry *, struct inode *, |
| 1066 | struct delayed_call *); |
| 1067 | get = inode->i_op->get_link; |
Al Viro | 8c1b456 | 2015-05-09 18:15:21 -0400 | [diff] [blame] | 1068 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1069 | res = get(NULL, inode, &last->done); |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 1070 | if (res == ERR_PTR(-ECHILD)) { |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1071 | if (unlikely(unlazy_walk(nd))) |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 1072 | return ERR_PTR(-ECHILD); |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1073 | res = get(dentry, inode, &last->done); |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 1074 | } |
| 1075 | } else { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1076 | res = get(dentry, inode, &last->done); |
Al Viro | 8c1b456 | 2015-05-09 18:15:21 -0400 | [diff] [blame] | 1077 | } |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1078 | if (IS_ERR_OR_NULL(res)) |
Al Viro | fab51e8 | 2015-05-10 11:01:00 -0400 | [diff] [blame] | 1079 | return res; |
Ian Kent | 051d381 | 2006-03-27 01:14:53 -0800 | [diff] [blame] | 1080 | } |
Al Viro | fab51e8 | 2015-05-10 11:01:00 -0400 | [diff] [blame] | 1081 | if (*res == '/') { |
Al Viro | 9e6697e | 2015-12-05 20:07:21 -0500 | [diff] [blame] | 1082 | if (!nd->root.mnt) |
| 1083 | set_root(nd); |
Al Viro | 248fb5b | 2015-12-05 20:51:58 -0500 | [diff] [blame] | 1084 | if (unlikely(nd_jump_root(nd))) |
| 1085 | return ERR_PTR(-ECHILD); |
Al Viro | fab51e8 | 2015-05-10 11:01:00 -0400 | [diff] [blame] | 1086 | while (unlikely(*++res == '/')) |
| 1087 | ; |
| 1088 | } |
| 1089 | if (!*res) |
| 1090 | res = NULL; |
Al Viro | 0a959df | 2015-04-18 18:23:41 -0400 | [diff] [blame] | 1091 | return res; |
| 1092 | } |
Al Viro | 6d7b5aa | 2012-06-10 04:15:17 -0400 | [diff] [blame] | 1093 | |
David Howells | f015f126 | 2012-06-25 12:55:28 +0100 | [diff] [blame] | 1094 | /* |
| 1095 | * follow_up - Find the mountpoint of path's vfsmount |
| 1096 | * |
| 1097 | * Given a path, find the mountpoint of its source file system. |
| 1098 | * Replace @path with the path of the mountpoint in the parent mount. |
| 1099 | * Up is towards /. |
| 1100 | * |
| 1101 | * Return 1 if we went up a level and 0 if we were already at the |
| 1102 | * root. |
| 1103 | */ |
Al Viro | bab77eb | 2009-04-18 03:26:48 -0400 | [diff] [blame] | 1104 | int follow_up(struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1105 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1106 | struct mount *mnt = real_mount(path->mnt); |
| 1107 | struct mount *parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1108 | struct dentry *mountpoint; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1109 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1110 | read_seqlock_excl(&mount_lock); |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1111 | parent = mnt->mnt_parent; |
Al Viro | 3c0a616 | 2012-07-18 17:32:50 +0400 | [diff] [blame] | 1112 | if (parent == mnt) { |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1113 | read_sequnlock_excl(&mount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1114 | return 0; |
| 1115 | } |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1116 | mntget(&parent->mnt); |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1117 | mountpoint = dget(mnt->mnt_mountpoint); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1118 | read_sequnlock_excl(&mount_lock); |
Al Viro | bab77eb | 2009-04-18 03:26:48 -0400 | [diff] [blame] | 1119 | dput(path->dentry); |
| 1120 | path->dentry = mountpoint; |
| 1121 | mntput(path->mnt); |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1122 | path->mnt = &parent->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1123 | return 1; |
| 1124 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 1125 | EXPORT_SYMBOL(follow_up); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1126 | |
Nick Piggin | b5c84bf | 2011-01-07 17:49:38 +1100 | [diff] [blame] | 1127 | /* |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1128 | * Perform an automount |
| 1129 | * - return -EISDIR to tell follow_managed() to stop and return the path we |
| 1130 | * were called with. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1131 | */ |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1132 | static int follow_automount(struct path *path, struct nameidata *nd, |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1133 | bool *need_mntput) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1134 | { |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1135 | struct vfsmount *mnt; |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1136 | int err; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1137 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1138 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) |
| 1139 | return -EREMOTE; |
Al Viro | 463ffb2 | 2005-06-06 13:36:05 -0700 | [diff] [blame] | 1140 | |
Miklos Szeredi | 0ec26fd | 2011-09-05 18:06:26 +0200 | [diff] [blame] | 1141 | /* We don't want to mount if someone's just doing a stat - |
| 1142 | * unless they're stat'ing a directory and appended a '/' to |
| 1143 | * the name. |
| 1144 | * |
| 1145 | * We do, however, want to mount if someone wants to open or |
| 1146 | * create a file of any type under the mountpoint, wants to |
| 1147 | * traverse through the mountpoint or wants to open the |
| 1148 | * mounted directory. Also, autofs may mark negative dentries |
| 1149 | * as being automount points. These will need the attentions |
| 1150 | * of the daemon to instantiate them before they can be used. |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1151 | */ |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1152 | if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
Ian Kent | 5d38f04 | 2017-11-29 16:11:26 -0800 | [diff] [blame] | 1153 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
| 1154 | path->dentry->d_inode) |
| 1155 | return -EISDIR; |
Miklos Szeredi | 0ec26fd | 2011-09-05 18:06:26 +0200 | [diff] [blame] | 1156 | |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1157 | nd->total_link_count++; |
| 1158 | if (nd->total_link_count >= 40) |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1159 | return -ELOOP; |
| 1160 | |
| 1161 | mnt = path->dentry->d_op->d_automount(path); |
| 1162 | if (IS_ERR(mnt)) { |
| 1163 | /* |
| 1164 | * The filesystem is allowed to return -EISDIR here to indicate |
| 1165 | * it doesn't want to automount. For instance, autofs would do |
| 1166 | * this so that its userspace daemon can mount on this dentry. |
| 1167 | * |
| 1168 | * However, we can only permit this if it's a terminal point in |
| 1169 | * the path being looked up; if it wasn't then the remainder of |
| 1170 | * the path is inaccessible and we should say so. |
| 1171 | */ |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1172 | if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1173 | return -EREMOTE; |
| 1174 | return PTR_ERR(mnt); |
| 1175 | } |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1176 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1177 | if (!mnt) /* mount collision */ |
| 1178 | return 0; |
| 1179 | |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1180 | if (!*need_mntput) { |
| 1181 | /* lock_mount() may release path->mnt on error */ |
| 1182 | mntget(path->mnt); |
| 1183 | *need_mntput = true; |
| 1184 | } |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1185 | err = finish_automount(mnt, path); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1186 | |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1187 | switch (err) { |
| 1188 | case -EBUSY: |
| 1189 | /* Someone else made a mount here whilst we were busy */ |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1190 | return 0; |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1191 | case 0: |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1192 | path_put(path); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1193 | path->mnt = mnt; |
| 1194 | path->dentry = dget(mnt->mnt_root); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1195 | return 0; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1196 | default: |
| 1197 | return err; |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1198 | } |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1199 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1200 | } |
| 1201 | |
| 1202 | /* |
| 1203 | * Handle a dentry that is managed in some way. |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1204 | * - Flagged for transit management (autofs) |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1205 | * - Flagged as mountpoint |
| 1206 | * - Flagged as automount point |
| 1207 | * |
| 1208 | * This may only be called in refwalk mode. |
| 1209 | * |
| 1210 | * Serialization is taken care of in namespace.c |
| 1211 | */ |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1212 | static int follow_managed(struct path *path, struct nameidata *nd) |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1213 | { |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1214 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1215 | unsigned managed; |
| 1216 | bool need_mntput = false; |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1217 | int ret = 0; |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1218 | |
| 1219 | /* Given that we're not holding a lock here, we retain the value in a |
| 1220 | * local variable for each dentry as we look at it so that we don't see |
| 1221 | * the components of that value change under us */ |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 1222 | while (managed = READ_ONCE(path->dentry->d_flags), |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1223 | managed &= DCACHE_MANAGED_DENTRY, |
| 1224 | unlikely(managed != 0)) { |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1225 | /* Allow the filesystem to manage the transit without i_mutex |
| 1226 | * being held. */ |
| 1227 | if (managed & DCACHE_MANAGE_TRANSIT) { |
| 1228 | BUG_ON(!path->dentry->d_op); |
| 1229 | BUG_ON(!path->dentry->d_op->d_manage); |
Ian Kent | fb5f51c | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1230 | ret = path->dentry->d_op->d_manage(path, false); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1231 | if (ret < 0) |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1232 | break; |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1233 | } |
| 1234 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1235 | /* Transit to a mounted filesystem. */ |
| 1236 | if (managed & DCACHE_MOUNTED) { |
| 1237 | struct vfsmount *mounted = lookup_mnt(path); |
| 1238 | if (mounted) { |
| 1239 | dput(path->dentry); |
| 1240 | if (need_mntput) |
| 1241 | mntput(path->mnt); |
| 1242 | path->mnt = mounted; |
| 1243 | path->dentry = dget(mounted->mnt_root); |
| 1244 | need_mntput = true; |
| 1245 | continue; |
| 1246 | } |
| 1247 | |
| 1248 | /* Something is mounted on this dentry in another |
| 1249 | * namespace and/or whatever was mounted there in this |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1250 | * namespace got unmounted before lookup_mnt() could |
| 1251 | * get it */ |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1252 | } |
| 1253 | |
| 1254 | /* Handle an automount point */ |
| 1255 | if (managed & DCACHE_NEED_AUTOMOUNT) { |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1256 | ret = follow_automount(path, nd, &need_mntput); |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1257 | if (ret < 0) |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1258 | break; |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1259 | continue; |
| 1260 | } |
| 1261 | |
| 1262 | /* We didn't change the current path point */ |
| 1263 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1264 | } |
Al Viro | 8aef188 | 2011-06-16 15:10:06 +0100 | [diff] [blame] | 1265 | |
| 1266 | if (need_mntput && path->mnt == mnt) |
| 1267 | mntput(path->mnt); |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1268 | if (ret == -EISDIR || !ret) |
| 1269 | ret = 1; |
Al Viro | 8402752e | 2015-04-22 10:30:08 -0400 | [diff] [blame] | 1270 | if (need_mntput) |
| 1271 | nd->flags |= LOOKUP_JUMPED; |
| 1272 | if (unlikely(ret < 0)) |
| 1273 | path_put_conditional(path, nd); |
| 1274 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1275 | } |
| 1276 | |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1277 | int follow_down_one(struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1278 | { |
| 1279 | struct vfsmount *mounted; |
| 1280 | |
Al Viro | 1c755af | 2009-04-18 14:06:57 -0400 | [diff] [blame] | 1281 | mounted = lookup_mnt(path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1282 | if (mounted) { |
Al Viro | 9393bd0 | 2009-04-18 13:58:15 -0400 | [diff] [blame] | 1283 | dput(path->dentry); |
| 1284 | mntput(path->mnt); |
| 1285 | path->mnt = mounted; |
| 1286 | path->dentry = dget(mounted->mnt_root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1287 | return 1; |
| 1288 | } |
| 1289 | return 0; |
| 1290 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 1291 | EXPORT_SYMBOL(follow_down_one); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1292 | |
Ian Kent | fb5f51c | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1293 | static inline int managed_dentry_rcu(const struct path *path) |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1294 | { |
Ian Kent | fb5f51c | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1295 | return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
| 1296 | path->dentry->d_op->d_manage(path, true) : 0; |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1297 | } |
| 1298 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1299 | /* |
Al Viro | 287548e | 2011-05-27 06:50:06 -0400 | [diff] [blame] | 1300 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
| 1301 | * we meet a managed dentry that would need blocking. |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1302 | */ |
| 1303 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1304 | struct inode **inode, unsigned *seqp) |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1305 | { |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1306 | for (;;) { |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 1307 | struct mount *mounted; |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1308 | /* |
| 1309 | * Don't forget we might have a non-mountpoint managed dentry |
| 1310 | * that wants to block transit. |
| 1311 | */ |
Ian Kent | fb5f51c | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1312 | switch (managed_dentry_rcu(path)) { |
NeilBrown | b8faf03 | 2014-08-04 17:06:29 +1000 | [diff] [blame] | 1313 | case -ECHILD: |
| 1314 | default: |
David Howells | ab90911 | 2011-01-14 18:46:51 +0000 | [diff] [blame] | 1315 | return false; |
NeilBrown | b8faf03 | 2014-08-04 17:06:29 +1000 | [diff] [blame] | 1316 | case -EISDIR: |
| 1317 | return true; |
| 1318 | case 0: |
| 1319 | break; |
| 1320 | } |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1321 | |
| 1322 | if (!d_mountpoint(path->dentry)) |
NeilBrown | b8faf03 | 2014-08-04 17:06:29 +1000 | [diff] [blame] | 1323 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
Ian Kent | 62a7375 | 2011-03-25 01:51:02 +0800 | [diff] [blame] | 1324 | |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 1325 | mounted = __lookup_mnt(path->mnt, path->dentry); |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1326 | if (!mounted) |
| 1327 | break; |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 1328 | path->mnt = &mounted->mnt; |
| 1329 | path->dentry = mounted->mnt.mnt_root; |
Al Viro | a3fbbde | 2011-11-07 21:21:26 +0000 | [diff] [blame] | 1330 | nd->flags |= LOOKUP_JUMPED; |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1331 | *seqp = read_seqcount_begin(&path->dentry->d_seq); |
Linus Torvalds | 5943026 | 2011-07-18 15:43:29 -0700 | [diff] [blame] | 1332 | /* |
| 1333 | * Update the inode too. We don't need to re-check the |
| 1334 | * dentry sequence number here after this d_inode read, |
| 1335 | * because a mount-point is always pinned. |
| 1336 | */ |
| 1337 | *inode = path->dentry->d_inode; |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1338 | } |
Al Viro | f5be3e2912 | 2014-09-13 21:50:45 -0400 | [diff] [blame] | 1339 | return !read_seqretry(&mount_lock, nd->m_seq) && |
NeilBrown | b8faf03 | 2014-08-04 17:06:29 +1000 | [diff] [blame] | 1340 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
Al Viro | 287548e | 2011-05-27 06:50:06 -0400 | [diff] [blame] | 1341 | } |
| 1342 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1343 | static int follow_dotdot_rcu(struct nameidata *nd) |
| 1344 | { |
Al Viro | 4023bfc | 2014-09-13 21:59:43 -0400 | [diff] [blame] | 1345 | struct inode *inode = nd->inode; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1346 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1347 | while (1) { |
Al Viro | aed434a | 2015-05-12 12:22:47 -0400 | [diff] [blame] | 1348 | if (path_equal(&nd->path, &nd->root)) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1349 | break; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1350 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
| 1351 | struct dentry *old = nd->path.dentry; |
| 1352 | struct dentry *parent = old->d_parent; |
| 1353 | unsigned seq; |
| 1354 | |
Al Viro | 4023bfc | 2014-09-13 21:59:43 -0400 | [diff] [blame] | 1355 | inode = parent->d_inode; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1356 | seq = read_seqcount_begin(&parent->d_seq); |
Al Viro | aed434a | 2015-05-12 12:22:47 -0400 | [diff] [blame] | 1357 | if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) |
| 1358 | return -ECHILD; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1359 | nd->path.dentry = parent; |
| 1360 | nd->seq = seq; |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 1361 | if (unlikely(!path_connected(&nd->path))) |
| 1362 | return -ENOENT; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1363 | break; |
Al Viro | aed434a | 2015-05-12 12:22:47 -0400 | [diff] [blame] | 1364 | } else { |
| 1365 | struct mount *mnt = real_mount(nd->path.mnt); |
| 1366 | struct mount *mparent = mnt->mnt_parent; |
| 1367 | struct dentry *mountpoint = mnt->mnt_mountpoint; |
| 1368 | struct inode *inode2 = mountpoint->d_inode; |
| 1369 | unsigned seq = read_seqcount_begin(&mountpoint->d_seq); |
| 1370 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) |
| 1371 | return -ECHILD; |
| 1372 | if (&mparent->mnt == nd->path.mnt) |
| 1373 | break; |
| 1374 | /* we know that mountpoint was pinned */ |
| 1375 | nd->path.dentry = mountpoint; |
| 1376 | nd->path.mnt = &mparent->mnt; |
| 1377 | inode = inode2; |
| 1378 | nd->seq = seq; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1379 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1380 | } |
Al Viro | aed434a | 2015-05-12 12:22:47 -0400 | [diff] [blame] | 1381 | while (unlikely(d_mountpoint(nd->path.dentry))) { |
Al Viro | b37199e | 2014-03-20 15:18:22 -0400 | [diff] [blame] | 1382 | struct mount *mounted; |
| 1383 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); |
Al Viro | aed434a | 2015-05-12 12:22:47 -0400 | [diff] [blame] | 1384 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) |
| 1385 | return -ECHILD; |
Al Viro | b37199e | 2014-03-20 15:18:22 -0400 | [diff] [blame] | 1386 | if (!mounted) |
| 1387 | break; |
| 1388 | nd->path.mnt = &mounted->mnt; |
| 1389 | nd->path.dentry = mounted->mnt.mnt_root; |
Al Viro | 4023bfc | 2014-09-13 21:59:43 -0400 | [diff] [blame] | 1390 | inode = nd->path.dentry->d_inode; |
Al Viro | b37199e | 2014-03-20 15:18:22 -0400 | [diff] [blame] | 1391 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
Al Viro | b37199e | 2014-03-20 15:18:22 -0400 | [diff] [blame] | 1392 | } |
Al Viro | 4023bfc | 2014-09-13 21:59:43 -0400 | [diff] [blame] | 1393 | nd->inode = inode; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1394 | return 0; |
| 1395 | } |
| 1396 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1397 | /* |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1398 | * Follow down to the covering mount currently visible to userspace. At each |
| 1399 | * point, the filesystem owning that dentry may be queried as to whether the |
| 1400 | * caller is permitted to proceed or not. |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1401 | */ |
Al Viro | 7cc90cc | 2011-03-18 09:04:20 -0400 | [diff] [blame] | 1402 | int follow_down(struct path *path) |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1403 | { |
| 1404 | unsigned managed; |
| 1405 | int ret; |
| 1406 | |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 1407 | while (managed = READ_ONCE(path->dentry->d_flags), |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1408 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { |
| 1409 | /* Allow the filesystem to manage the transit without i_mutex |
| 1410 | * being held. |
| 1411 | * |
| 1412 | * We indicate to the filesystem if someone is trying to mount |
| 1413 | * something here. This gives autofs the chance to deny anyone |
| 1414 | * other than its daemon the right to mount on its |
| 1415 | * superstructure. |
| 1416 | * |
| 1417 | * The filesystem may sleep at this point. |
| 1418 | */ |
| 1419 | if (managed & DCACHE_MANAGE_TRANSIT) { |
| 1420 | BUG_ON(!path->dentry->d_op); |
| 1421 | BUG_ON(!path->dentry->d_op->d_manage); |
Ian Kent | fb5f51c | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1422 | ret = path->dentry->d_op->d_manage(path, false); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1423 | if (ret < 0) |
| 1424 | return ret == -EISDIR ? 0 : ret; |
| 1425 | } |
| 1426 | |
| 1427 | /* Transit to a mounted filesystem. */ |
| 1428 | if (managed & DCACHE_MOUNTED) { |
| 1429 | struct vfsmount *mounted = lookup_mnt(path); |
| 1430 | if (!mounted) |
| 1431 | break; |
| 1432 | dput(path->dentry); |
| 1433 | mntput(path->mnt); |
| 1434 | path->mnt = mounted; |
| 1435 | path->dentry = dget(mounted->mnt_root); |
| 1436 | continue; |
| 1437 | } |
| 1438 | |
| 1439 | /* Don't handle automount points here */ |
| 1440 | break; |
| 1441 | } |
| 1442 | return 0; |
| 1443 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 1444 | EXPORT_SYMBOL(follow_down); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1445 | |
| 1446 | /* |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1447 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() |
| 1448 | */ |
| 1449 | static void follow_mount(struct path *path) |
| 1450 | { |
| 1451 | while (d_mountpoint(path->dentry)) { |
| 1452 | struct vfsmount *mounted = lookup_mnt(path); |
| 1453 | if (!mounted) |
| 1454 | break; |
| 1455 | dput(path->dentry); |
| 1456 | mntput(path->mnt); |
| 1457 | path->mnt = mounted; |
| 1458 | path->dentry = dget(mounted->mnt_root); |
| 1459 | } |
| 1460 | } |
| 1461 | |
Eric W. Biederman | eedf265 | 2016-06-02 10:29:47 -0500 | [diff] [blame] | 1462 | static int path_parent_directory(struct path *path) |
| 1463 | { |
| 1464 | struct dentry *old = path->dentry; |
| 1465 | /* rare case of legitimate dget_parent()... */ |
| 1466 | path->dentry = dget_parent(path->dentry); |
| 1467 | dput(old); |
| 1468 | if (unlikely(!path_connected(path))) |
| 1469 | return -ENOENT; |
| 1470 | return 0; |
| 1471 | } |
| 1472 | |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 1473 | static int follow_dotdot(struct nameidata *nd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1474 | { |
| 1475 | while(1) { |
Danilo Krummrich | 030c7e0 | 2018-04-23 10:30:59 +0200 | [diff] [blame] | 1476 | if (path_equal(&nd->path, &nd->root)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1477 | break; |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1478 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
Eric W. Biederman | eedf265 | 2016-06-02 10:29:47 -0500 | [diff] [blame] | 1479 | int ret = path_parent_directory(&nd->path); |
| 1480 | if (ret) |
| 1481 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1482 | break; |
| 1483 | } |
Al Viro | 3088dd7 | 2010-01-30 15:47:29 -0500 | [diff] [blame] | 1484 | if (!follow_up(&nd->path)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1485 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1486 | } |
Al Viro | 79ed022 | 2009-04-18 13:59:41 -0400 | [diff] [blame] | 1487 | follow_mount(&nd->path); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1488 | nd->inode = nd->path.dentry->d_inode; |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 1489 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1490 | } |
| 1491 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1492 | /* |
Oleg Drokin | f4fdace | 2016-07-07 22:04:04 -0400 | [diff] [blame] | 1493 | * This looks up the name in dcache and possibly revalidates the found dentry. |
| 1494 | * NULL is returned if the dentry does not exist in the cache. |
Nick Piggin | baa0389 | 2010-08-18 04:37:31 +1000 | [diff] [blame] | 1495 | */ |
Al Viro | e3c1392 | 2016-03-06 14:03:27 -0500 | [diff] [blame] | 1496 | static struct dentry *lookup_dcache(const struct qstr *name, |
| 1497 | struct dentry *dir, |
Al Viro | 6c51e51 | 2016-03-05 20:09:32 -0500 | [diff] [blame] | 1498 | unsigned int flags) |
Nick Piggin | baa0389 | 2010-08-18 04:37:31 +1000 | [diff] [blame] | 1499 | { |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 1500 | struct dentry *dentry = d_lookup(dir, name); |
Miklos Szeredi | bad6118 | 2012-03-26 12:54:24 +0200 | [diff] [blame] | 1501 | if (dentry) { |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 1502 | int error = d_revalidate(dentry, flags); |
| 1503 | if (unlikely(error <= 0)) { |
| 1504 | if (!error) |
| 1505 | d_invalidate(dentry); |
| 1506 | dput(dentry); |
| 1507 | return ERR_PTR(error); |
Miklos Szeredi | bad6118 | 2012-03-26 12:54:24 +0200 | [diff] [blame] | 1508 | } |
| 1509 | } |
Nick Piggin | baa0389 | 2010-08-18 04:37:31 +1000 | [diff] [blame] | 1510 | return dentry; |
| 1511 | } |
| 1512 | |
| 1513 | /* |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1514 | * Parent directory has inode locked exclusive. This is one |
| 1515 | * and only case when ->lookup() gets called on non in-lookup |
| 1516 | * dentries - as the matter of fact, this only gets called |
| 1517 | * when directory is guaranteed to have no in-lookup children |
| 1518 | * at all. |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1519 | */ |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1520 | static struct dentry *__lookup_hash(const struct qstr *name, |
| 1521 | struct dentry *base, unsigned int flags) |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1522 | { |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1523 | struct dentry *dentry = lookup_dcache(name, base, flags); |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1524 | struct dentry *old; |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1525 | struct inode *dir = base->d_inode; |
| 1526 | |
| 1527 | if (dentry) |
| 1528 | return dentry; |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1529 | |
| 1530 | /* Don't create child dentry for a dead directory. */ |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1531 | if (unlikely(IS_DEADDIR(dir))) |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1532 | return ERR_PTR(-ENOENT); |
Al Viro | a03ece5 | 2018-03-08 11:00:45 -0500 | [diff] [blame] | 1533 | |
| 1534 | dentry = d_alloc(base, name); |
| 1535 | if (unlikely(!dentry)) |
| 1536 | return ERR_PTR(-ENOMEM); |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1537 | |
Al Viro | 72bd866 | 2012-06-10 17:17:17 -0400 | [diff] [blame] | 1538 | old = dir->i_op->lookup(dir, dentry, flags); |
Josef Bacik | 44396f4 | 2011-05-31 11:58:49 -0400 | [diff] [blame] | 1539 | if (unlikely(old)) { |
| 1540 | dput(dentry); |
| 1541 | dentry = old; |
| 1542 | } |
| 1543 | return dentry; |
| 1544 | } |
| 1545 | |
Al Viro | e97cdc8 | 2013-01-24 18:16:00 -0500 | [diff] [blame] | 1546 | static int lookup_fast(struct nameidata *nd, |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1547 | struct path *path, struct inode **inode, |
| 1548 | unsigned *seqp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1549 | { |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1550 | struct vfsmount *mnt = nd->path.mnt; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1551 | struct dentry *dentry, *parent = nd->path.dentry; |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1552 | int status = 1; |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1553 | int err; |
| 1554 | |
Al Viro | 3cac260 | 2009-08-13 18:27:43 +0400 | [diff] [blame] | 1555 | /* |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 1556 | * Rename seqlock is not required here because in the off chance |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1557 | * of a false negative due to a concurrent rename, the caller is |
| 1558 | * going to fall back to non-racy lookup. |
Nick Piggin | b04f784 | 2010-08-18 04:37:34 +1000 | [diff] [blame] | 1559 | */ |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1560 | if (nd->flags & LOOKUP_RCU) { |
| 1561 | unsigned seq; |
Al Viro | 766c4cb | 2015-05-07 19:24:57 -0400 | [diff] [blame] | 1562 | bool negative; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 1563 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1564 | if (unlikely(!dentry)) { |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1565 | if (unlazy_walk(nd)) |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1566 | return -ECHILD; |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1567 | return 0; |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1568 | } |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1569 | |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1570 | /* |
| 1571 | * This sequence count validates that the inode matches |
| 1572 | * the dentry name information from lookup. |
| 1573 | */ |
David Howells | 63afdfc | 2015-05-06 15:59:00 +0100 | [diff] [blame] | 1574 | *inode = d_backing_inode(dentry); |
Al Viro | 766c4cb | 2015-05-07 19:24:57 -0400 | [diff] [blame] | 1575 | negative = d_is_negative(dentry); |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1576 | if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) |
Linus Torvalds | 12f8ad4 | 2012-05-04 14:59:14 -0700 | [diff] [blame] | 1577 | return -ECHILD; |
| 1578 | |
| 1579 | /* |
| 1580 | * This sequence count validates that the parent had no |
| 1581 | * changes while we did the lookup of the dentry above. |
| 1582 | * |
| 1583 | * The memory barrier in read_seqcount_begin of child is |
| 1584 | * enough, we can use __read_seqcount_retry here. |
| 1585 | */ |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1586 | if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1587 | return -ECHILD; |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1588 | |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1589 | *seqp = seq; |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 1590 | status = d_revalidate(dentry, nd->flags); |
Al Viro | 209a7fb | 2017-01-09 01:35:39 -0500 | [diff] [blame] | 1591 | if (likely(status > 0)) { |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1592 | /* |
| 1593 | * Note: do negative dentry check after revalidation in |
| 1594 | * case that drops it. |
| 1595 | */ |
| 1596 | if (unlikely(negative)) |
| 1597 | return -ENOENT; |
| 1598 | path->mnt = mnt; |
| 1599 | path->dentry = dentry; |
| 1600 | if (likely(__follow_mount_rcu(nd, path, inode, seqp))) |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1601 | return 1; |
Al Viro | 2464308 | 2011-02-15 01:26:22 -0500 | [diff] [blame] | 1602 | } |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1603 | if (unlazy_child(nd, dentry, seq)) |
Al Viro | 209a7fb | 2017-01-09 01:35:39 -0500 | [diff] [blame] | 1604 | return -ECHILD; |
| 1605 | if (unlikely(status == -ECHILD)) |
| 1606 | /* we'd been told to redo it in non-rcu mode */ |
| 1607 | status = d_revalidate(dentry, nd->flags); |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1608 | } else { |
Al Viro | e97cdc8 | 2013-01-24 18:16:00 -0500 | [diff] [blame] | 1609 | dentry = __d_lookup(parent, &nd->last); |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1610 | if (unlikely(!dentry)) |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1611 | return 0; |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 1612 | status = d_revalidate(dentry, nd->flags); |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 1613 | } |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1614 | if (unlikely(status <= 0)) { |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1615 | if (!status) |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1616 | d_invalidate(dentry); |
Eric W. Biederman | 5542aa2 | 2014-02-13 09:46:25 -0800 | [diff] [blame] | 1617 | dput(dentry); |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1618 | return status; |
Al Viro | 5a18fff | 2011-03-11 04:44:53 -0500 | [diff] [blame] | 1619 | } |
Al Viro | 766c4cb | 2015-05-07 19:24:57 -0400 | [diff] [blame] | 1620 | if (unlikely(d_is_negative(dentry))) { |
| 1621 | dput(dentry); |
| 1622 | return -ENOENT; |
| 1623 | } |
Al Viro | 5d0f49c | 2016-03-05 21:32:53 -0500 | [diff] [blame] | 1624 | |
David Howells | 9875cf8 | 2011-01-14 18:45:21 +0000 | [diff] [blame] | 1625 | path->mnt = mnt; |
| 1626 | path->dentry = dentry; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1627 | err = follow_managed(path, nd); |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1628 | if (likely(err > 0)) |
David Howells | 63afdfc | 2015-05-06 15:59:00 +0100 | [diff] [blame] | 1629 | *inode = d_backing_inode(path->dentry); |
Al Viro | 8402752e | 2015-04-22 10:30:08 -0400 | [diff] [blame] | 1630 | return err; |
Miklos Szeredi | 697f514 | 2012-05-21 17:30:05 +0200 | [diff] [blame] | 1631 | } |
| 1632 | |
| 1633 | /* Fast lookup failed, do it the slow way */ |
Al Viro | 88d8331 | 2018-04-06 16:43:47 -0400 | [diff] [blame] | 1634 | static struct dentry *__lookup_slow(const struct qstr *name, |
| 1635 | struct dentry *dir, |
| 1636 | unsigned int flags) |
Miklos Szeredi | 697f514 | 2012-05-21 17:30:05 +0200 | [diff] [blame] | 1637 | { |
Al Viro | 88d8331 | 2018-04-06 16:43:47 -0400 | [diff] [blame] | 1638 | struct dentry *dentry, *old; |
Al Viro | 1936386 | 2016-04-14 19:33:34 -0400 | [diff] [blame] | 1639 | struct inode *inode = dir->d_inode; |
Al Viro | d9171b9 | 2016-04-15 03:33:13 -0400 | [diff] [blame] | 1640 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); |
Al Viro | 1936386 | 2016-04-14 19:33:34 -0400 | [diff] [blame] | 1641 | |
Al Viro | 1936386 | 2016-04-14 19:33:34 -0400 | [diff] [blame] | 1642 | /* Don't go there if it's already dead */ |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1643 | if (unlikely(IS_DEADDIR(inode))) |
Al Viro | 88d8331 | 2018-04-06 16:43:47 -0400 | [diff] [blame] | 1644 | return ERR_PTR(-ENOENT); |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1645 | again: |
Al Viro | d9171b9 | 2016-04-15 03:33:13 -0400 | [diff] [blame] | 1646 | dentry = d_alloc_parallel(dir, name, &wq); |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1647 | if (IS_ERR(dentry)) |
Al Viro | 88d8331 | 2018-04-06 16:43:47 -0400 | [diff] [blame] | 1648 | return dentry; |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1649 | if (unlikely(!d_in_lookup(dentry))) { |
Al Viro | a89f833 | 2017-01-09 22:25:28 -0500 | [diff] [blame] | 1650 | if (!(flags & LOOKUP_NO_REVAL)) { |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 1651 | int error = d_revalidate(dentry, flags); |
| 1652 | if (unlikely(error <= 0)) { |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1653 | if (!error) { |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 1654 | d_invalidate(dentry); |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1655 | dput(dentry); |
| 1656 | goto again; |
| 1657 | } |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 1658 | dput(dentry); |
| 1659 | dentry = ERR_PTR(error); |
| 1660 | } |
| 1661 | } |
Al Viro | 94bdd65 | 2016-04-15 02:42:04 -0400 | [diff] [blame] | 1662 | } else { |
| 1663 | old = inode->i_op->lookup(inode, dentry, flags); |
| 1664 | d_lookup_done(dentry); |
| 1665 | if (unlikely(old)) { |
| 1666 | dput(dentry); |
| 1667 | dentry = old; |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 1668 | } |
| 1669 | } |
Al Viro | e3c1392 | 2016-03-06 14:03:27 -0500 | [diff] [blame] | 1670 | return dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1671 | } |
| 1672 | |
Al Viro | 88d8331 | 2018-04-06 16:43:47 -0400 | [diff] [blame] | 1673 | static struct dentry *lookup_slow(const struct qstr *name, |
| 1674 | struct dentry *dir, |
| 1675 | unsigned int flags) |
| 1676 | { |
| 1677 | struct inode *inode = dir->d_inode; |
| 1678 | struct dentry *res; |
| 1679 | inode_lock_shared(inode); |
| 1680 | res = __lookup_slow(name, dir, flags); |
| 1681 | inode_unlock_shared(inode); |
| 1682 | return res; |
| 1683 | } |
| 1684 | |
Al Viro | 52094c8 | 2011-02-21 21:34:47 -0500 | [diff] [blame] | 1685 | static inline int may_lookup(struct nameidata *nd) |
| 1686 | { |
| 1687 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 4ad5abb | 2011-06-20 19:57:03 -0400 | [diff] [blame] | 1688 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
Al Viro | 52094c8 | 2011-02-21 21:34:47 -0500 | [diff] [blame] | 1689 | if (err != -ECHILD) |
| 1690 | return err; |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1691 | if (unlazy_walk(nd)) |
Al Viro | 52094c8 | 2011-02-21 21:34:47 -0500 | [diff] [blame] | 1692 | return -ECHILD; |
| 1693 | } |
Al Viro | 4ad5abb | 2011-06-20 19:57:03 -0400 | [diff] [blame] | 1694 | return inode_permission(nd->inode, MAY_EXEC); |
Al Viro | 52094c8 | 2011-02-21 21:34:47 -0500 | [diff] [blame] | 1695 | } |
| 1696 | |
Al Viro | 9856fa1 | 2011-03-04 14:22:06 -0500 | [diff] [blame] | 1697 | static inline int handle_dots(struct nameidata *nd, int type) |
| 1698 | { |
| 1699 | if (type == LAST_DOTDOT) { |
Al Viro | 9e6697e | 2015-12-05 20:07:21 -0500 | [diff] [blame] | 1700 | if (!nd->root.mnt) |
| 1701 | set_root(nd); |
Al Viro | 9856fa1 | 2011-03-04 14:22:06 -0500 | [diff] [blame] | 1702 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 70291ae | 2015-05-04 07:53:00 -0400 | [diff] [blame] | 1703 | return follow_dotdot_rcu(nd); |
Al Viro | 9856fa1 | 2011-03-04 14:22:06 -0500 | [diff] [blame] | 1704 | } else |
Eric W. Biederman | 397d425 | 2015-08-15 20:27:13 -0500 | [diff] [blame] | 1705 | return follow_dotdot(nd); |
Al Viro | 9856fa1 | 2011-03-04 14:22:06 -0500 | [diff] [blame] | 1706 | } |
| 1707 | return 0; |
| 1708 | } |
| 1709 | |
Al Viro | 181548c | 2015-05-07 19:54:34 -0400 | [diff] [blame] | 1710 | static int pick_link(struct nameidata *nd, struct path *link, |
| 1711 | struct inode *inode, unsigned seq) |
Al Viro | d63ff28 | 2015-05-04 18:13:23 -0400 | [diff] [blame] | 1712 | { |
Al Viro | 626de99 | 2015-05-04 18:26:59 -0400 | [diff] [blame] | 1713 | int error; |
Al Viro | 1cf2665 | 2015-05-06 16:01:56 -0400 | [diff] [blame] | 1714 | struct saved *last; |
NeilBrown | 756daf2 | 2015-03-23 13:37:38 +1100 | [diff] [blame] | 1715 | if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { |
Al Viro | 626de99 | 2015-05-04 18:26:59 -0400 | [diff] [blame] | 1716 | path_to_nameidata(link, nd); |
| 1717 | return -ELOOP; |
| 1718 | } |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 1719 | if (!(nd->flags & LOOKUP_RCU)) { |
Al Viro | 7973387a | 2015-05-09 12:55:43 -0400 | [diff] [blame] | 1720 | if (link->mnt == nd->path.mnt) |
| 1721 | mntget(link->mnt); |
Al Viro | d63ff28 | 2015-05-04 18:13:23 -0400 | [diff] [blame] | 1722 | } |
Al Viro | 626de99 | 2015-05-04 18:26:59 -0400 | [diff] [blame] | 1723 | error = nd_alloc_stack(nd); |
| 1724 | if (unlikely(error)) { |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 1725 | if (error == -ECHILD) { |
Al Viro | ad1633a | 2017-01-08 22:35:31 -0500 | [diff] [blame] | 1726 | if (unlikely(!legitimize_path(nd, link, seq))) { |
| 1727 | drop_links(nd); |
| 1728 | nd->depth = 0; |
| 1729 | nd->flags &= ~LOOKUP_RCU; |
| 1730 | nd->path.mnt = NULL; |
| 1731 | nd->path.dentry = NULL; |
Al Viro | ad1633a | 2017-01-08 22:35:31 -0500 | [diff] [blame] | 1732 | rcu_read_unlock(); |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 1733 | } else if (likely(unlazy_walk(nd)) == 0) |
Al Viro | ad1633a | 2017-01-08 22:35:31 -0500 | [diff] [blame] | 1734 | error = nd_alloc_stack(nd); |
Al Viro | bc40aee | 2015-05-09 13:04:24 -0400 | [diff] [blame] | 1735 | } |
| 1736 | if (error) { |
| 1737 | path_put(link); |
| 1738 | return error; |
| 1739 | } |
Al Viro | 626de99 | 2015-05-04 18:26:59 -0400 | [diff] [blame] | 1740 | } |
| 1741 | |
Al Viro | ab10492 | 2015-05-10 11:50:01 -0400 | [diff] [blame] | 1742 | last = nd->stack + nd->depth++; |
Al Viro | 1cf2665 | 2015-05-06 16:01:56 -0400 | [diff] [blame] | 1743 | last->link = *link; |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 1744 | clear_delayed_call(&last->done); |
| 1745 | nd->link_inode = inode; |
Al Viro | 0450b2d | 2015-05-08 13:23:53 -0400 | [diff] [blame] | 1746 | last->seq = seq; |
Al Viro | d63ff28 | 2015-05-04 18:13:23 -0400 | [diff] [blame] | 1747 | return 1; |
| 1748 | } |
| 1749 | |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1750 | enum {WALK_FOLLOW = 1, WALK_MORE = 2}; |
Al Viro | 31d66bc | 2016-11-14 01:43:34 -0500 | [diff] [blame] | 1751 | |
Linus Torvalds | 3ddcd05 | 2011-08-06 22:45:50 -0700 | [diff] [blame] | 1752 | /* |
| 1753 | * Do we need to follow links? We _really_ want to be able |
| 1754 | * to do this check without having to look at inode->i_op, |
| 1755 | * so we keep a cache of "no, this doesn't need follow_link" |
| 1756 | * for the common case. |
| 1757 | */ |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1758 | static inline int step_into(struct nameidata *nd, struct path *path, |
| 1759 | int flags, struct inode *inode, unsigned seq) |
Linus Torvalds | 3ddcd05 | 2011-08-06 22:45:50 -0700 | [diff] [blame] | 1760 | { |
Al Viro | 31d66bc | 2016-11-14 01:43:34 -0500 | [diff] [blame] | 1761 | if (!(flags & WALK_MORE) && nd->depth) |
| 1762 | put_link(nd); |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1763 | if (likely(!d_is_symlink(path->dentry)) || |
| 1764 | !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) { |
| 1765 | /* not a symlink or should not follow */ |
| 1766 | path_to_nameidata(path, nd); |
| 1767 | nd->inode = inode; |
| 1768 | nd->seq = seq; |
Al Viro | d63ff28 | 2015-05-04 18:13:23 -0400 | [diff] [blame] | 1769 | return 0; |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1770 | } |
Al Viro | a7f7754 | 2016-02-27 19:31:01 -0500 | [diff] [blame] | 1771 | /* make sure that d_is_symlink above matches inode */ |
| 1772 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1773 | if (read_seqcount_retry(&path->dentry->d_seq, seq)) |
Al Viro | a7f7754 | 2016-02-27 19:31:01 -0500 | [diff] [blame] | 1774 | return -ECHILD; |
| 1775 | } |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1776 | return pick_link(nd, path, inode, seq); |
Linus Torvalds | 3ddcd05 | 2011-08-06 22:45:50 -0700 | [diff] [blame] | 1777 | } |
| 1778 | |
Al Viro | 4693a54 | 2015-05-04 17:47:11 -0400 | [diff] [blame] | 1779 | static int walk_component(struct nameidata *nd, int flags) |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 1780 | { |
Al Viro | caa85634 | 2015-04-22 17:52:47 -0400 | [diff] [blame] | 1781 | struct path path; |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 1782 | struct inode *inode; |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1783 | unsigned seq; |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 1784 | int err; |
| 1785 | /* |
| 1786 | * "." and ".." are special - ".." especially so because it has |
| 1787 | * to be able to know about the current root directory and |
| 1788 | * parent relationships. |
| 1789 | */ |
Al Viro | 4693a54 | 2015-05-04 17:47:11 -0400 | [diff] [blame] | 1790 | if (unlikely(nd->last_type != LAST_NORM)) { |
| 1791 | err = handle_dots(nd, nd->last_type); |
Al Viro | 1c4ff1a | 2016-11-14 01:39:36 -0500 | [diff] [blame] | 1792 | if (!(flags & WALK_MORE) && nd->depth) |
Al Viro | 4693a54 | 2015-05-04 17:47:11 -0400 | [diff] [blame] | 1793 | put_link(nd); |
| 1794 | return err; |
| 1795 | } |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1796 | err = lookup_fast(nd, &path, &inode, &seq); |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 1797 | if (unlikely(err <= 0)) { |
Miklos Szeredi | 697f514 | 2012-05-21 17:30:05 +0200 | [diff] [blame] | 1798 | if (err < 0) |
Al Viro | f0a9ba7 | 2015-05-04 07:59:30 -0400 | [diff] [blame] | 1799 | return err; |
Al Viro | e3c1392 | 2016-03-06 14:03:27 -0500 | [diff] [blame] | 1800 | path.dentry = lookup_slow(&nd->last, nd->path.dentry, |
| 1801 | nd->flags); |
| 1802 | if (IS_ERR(path.dentry)) |
| 1803 | return PTR_ERR(path.dentry); |
Al Viro | 7500c38 | 2016-03-31 00:23:05 -0400 | [diff] [blame] | 1804 | |
Al Viro | e3c1392 | 2016-03-06 14:03:27 -0500 | [diff] [blame] | 1805 | path.mnt = nd->path.mnt; |
| 1806 | err = follow_managed(&path, nd); |
| 1807 | if (unlikely(err < 0)) |
Al Viro | f0a9ba7 | 2015-05-04 07:59:30 -0400 | [diff] [blame] | 1808 | return err; |
Miklos Szeredi | 697f514 | 2012-05-21 17:30:05 +0200 | [diff] [blame] | 1809 | |
Al Viro | 7500c38 | 2016-03-31 00:23:05 -0400 | [diff] [blame] | 1810 | if (unlikely(d_is_negative(path.dentry))) { |
| 1811 | path_to_nameidata(&path, nd); |
| 1812 | return -ENOENT; |
| 1813 | } |
| 1814 | |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 1815 | seq = 0; /* we are already out of RCU mode */ |
Al Viro | d456564 | 2016-02-27 19:23:16 -0500 | [diff] [blame] | 1816 | inode = d_backing_inode(path.dentry); |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 1817 | } |
Miklos Szeredi | 697f514 | 2012-05-21 17:30:05 +0200 | [diff] [blame] | 1818 | |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 1819 | return step_into(nd, &path, flags, inode, seq); |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 1820 | } |
| 1821 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1822 | /* |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1823 | * We can do the critical dentry name comparison and hashing |
| 1824 | * operations one word at a time, but we are limited to: |
| 1825 | * |
| 1826 | * - Architectures with fast unaligned word accesses. We could |
| 1827 | * do a "get_unaligned()" if this helps and is sufficiently |
| 1828 | * fast. |
| 1829 | * |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1830 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
| 1831 | * do not trap on the (extremely unlikely) case of a page |
| 1832 | * crossing operation. |
| 1833 | * |
| 1834 | * - Furthermore, we need an efficient 64-bit compile for the |
| 1835 | * 64-bit case in order to generate the "number of bytes in |
| 1836 | * the final mask". Again, that could be replaced with a |
| 1837 | * efficient population count instruction or similar. |
| 1838 | */ |
| 1839 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
| 1840 | |
Linus Torvalds | f68e556 | 2012-04-06 13:54:56 -0700 | [diff] [blame] | 1841 | #include <asm/word-at-a-time.h> |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1842 | |
George Spelvin | 468a942 | 2016-05-26 22:11:51 -0400 | [diff] [blame] | 1843 | #ifdef HASH_MIX |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1844 | |
George Spelvin | 468a942 | 2016-05-26 22:11:51 -0400 | [diff] [blame] | 1845 | /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ |
| 1846 | |
| 1847 | #elif defined(CONFIG_64BIT) |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1848 | /* |
| 1849 | * Register pressure in the mixing function is an issue, particularly |
| 1850 | * on 32-bit x86, but almost any function requires one state value and |
| 1851 | * one temporary. Instead, use a function designed for two state values |
| 1852 | * and no temporaries. |
| 1853 | * |
| 1854 | * This function cannot create a collision in only two iterations, so |
| 1855 | * we have two iterations to achieve avalanche. In those two iterations, |
| 1856 | * we have six layers of mixing, which is enough to spread one bit's |
| 1857 | * influence out to 2^6 = 64 state bits. |
| 1858 | * |
| 1859 | * Rotate constants are scored by considering either 64 one-bit input |
| 1860 | * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the |
| 1861 | * probability of that delta causing a change to each of the 128 output |
| 1862 | * bits, using a sample of random initial states. |
| 1863 | * |
| 1864 | * The Shannon entropy of the computed probabilities is then summed |
| 1865 | * to produce a score. Ideally, any input change has a 50% chance of |
| 1866 | * toggling any given output bit. |
| 1867 | * |
| 1868 | * Mixing scores (in bits) for (12,45): |
| 1869 | * Input delta: 1-bit 2-bit |
| 1870 | * 1 round: 713.3 42542.6 |
| 1871 | * 2 rounds: 2753.7 140389.8 |
| 1872 | * 3 rounds: 5954.1 233458.2 |
| 1873 | * 4 rounds: 7862.6 256672.2 |
| 1874 | * Perfect: 8192 258048 |
| 1875 | * (64*128) (64*63/2 * 128) |
| 1876 | */ |
| 1877 | #define HASH_MIX(x, y, a) \ |
| 1878 | ( x ^= (a), \ |
| 1879 | y ^= x, x = rol64(x,12),\ |
| 1880 | x += y, y = rol64(y,45),\ |
| 1881 | y *= 9 ) |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1882 | |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1883 | /* |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1884 | * Fold two longs into one 32-bit hash value. This must be fast, but |
| 1885 | * latency isn't quite as critical, as there is a fair bit of additional |
| 1886 | * work done before the hash value is used. |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1887 | */ |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1888 | static inline unsigned int fold_hash(unsigned long x, unsigned long y) |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1889 | { |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1890 | y ^= x * GOLDEN_RATIO_64; |
| 1891 | y *= GOLDEN_RATIO_64; |
| 1892 | return y >> 32; |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1893 | } |
| 1894 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1895 | #else /* 32-bit case */ |
| 1896 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1897 | /* |
| 1898 | * Mixing scores (in bits) for (7,20): |
| 1899 | * Input delta: 1-bit 2-bit |
| 1900 | * 1 round: 330.3 9201.6 |
| 1901 | * 2 rounds: 1246.4 25475.4 |
| 1902 | * 3 rounds: 1907.1 31295.1 |
| 1903 | * 4 rounds: 2042.3 31718.6 |
| 1904 | * Perfect: 2048 31744 |
| 1905 | * (32*64) (32*31/2 * 64) |
| 1906 | */ |
| 1907 | #define HASH_MIX(x, y, a) \ |
| 1908 | ( x ^= (a), \ |
| 1909 | y ^= x, x = rol32(x, 7),\ |
| 1910 | x += y, y = rol32(y,20),\ |
| 1911 | y *= 9 ) |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1912 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1913 | static inline unsigned int fold_hash(unsigned long x, unsigned long y) |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1914 | { |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1915 | /* Use arch-optimized multiply if one exists */ |
| 1916 | return __hash_32(y ^ __hash_32(x)); |
George Spelvin | 0fed3ac | 2016-05-02 06:31:01 -0400 | [diff] [blame] | 1917 | } |
| 1918 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1919 | #endif |
| 1920 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1921 | /* |
| 1922 | * Return the hash of a string of known length. This is carfully |
| 1923 | * designed to match hash_name(), which is the more critical function. |
| 1924 | * In particular, we must end by hashing a final word containing 0..7 |
| 1925 | * payload bytes, to match the way that hash_name() iterates until it |
| 1926 | * finds the delimiter after the name. |
| 1927 | */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1928 | unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1929 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1930 | unsigned long a, x = 0, y = (unsigned long)salt; |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1931 | |
| 1932 | for (;;) { |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1933 | if (!len) |
| 1934 | goto done; |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 1935 | a = load_unaligned_zeropad(name); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1936 | if (len < sizeof(unsigned long)) |
| 1937 | break; |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1938 | HASH_MIX(x, y, a); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1939 | name += sizeof(unsigned long); |
| 1940 | len -= sizeof(unsigned long); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1941 | } |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1942 | x ^= a & bytemask_from_count(len); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1943 | done: |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1944 | return fold_hash(x, y); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1945 | } |
| 1946 | EXPORT_SYMBOL(full_name_hash); |
| 1947 | |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1948 | /* Return the "hash_len" (hash and length) of a null-terminated string */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1949 | u64 hashlen_string(const void *salt, const char *name) |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1950 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1951 | unsigned long a = 0, x = 0, y = (unsigned long)salt; |
| 1952 | unsigned long adata, mask, len; |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1953 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
| 1954 | |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1955 | len = 0; |
| 1956 | goto inside; |
| 1957 | |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1958 | do { |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1959 | HASH_MIX(x, y, a); |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1960 | len += sizeof(unsigned long); |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1961 | inside: |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1962 | a = load_unaligned_zeropad(name+len); |
| 1963 | } while (!has_zero(a, &adata, &constants)); |
| 1964 | |
| 1965 | adata = prep_zero_mask(a, adata, &constants); |
| 1966 | mask = create_zero_mask(adata); |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1967 | x ^= a & zero_bytemask(mask); |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1968 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1969 | return hashlen_create(fold_hash(x, y), len + find_zero(mask)); |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 1970 | } |
| 1971 | EXPORT_SYMBOL(hashlen_string); |
| 1972 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1973 | /* |
| 1974 | * Calculate the length and hash of the path component, and |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 1975 | * return the "hash_len" as the result. |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1976 | */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1977 | static inline u64 hash_name(const void *salt, const char *name) |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1978 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1979 | unsigned long a = 0, b, x = 0, y = (unsigned long)salt; |
| 1980 | unsigned long adata, bdata, mask, len; |
Linus Torvalds | 36126f8 | 2012-05-26 10:43:17 -0700 | [diff] [blame] | 1981 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1982 | |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1983 | len = 0; |
| 1984 | goto inside; |
| 1985 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1986 | do { |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1987 | HASH_MIX(x, y, a); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1988 | len += sizeof(unsigned long); |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 1989 | inside: |
Linus Torvalds | e419b4c | 2012-05-03 10:16:43 -0700 | [diff] [blame] | 1990 | a = load_unaligned_zeropad(name+len); |
Linus Torvalds | 36126f8 | 2012-05-26 10:43:17 -0700 | [diff] [blame] | 1991 | b = a ^ REPEAT_BYTE('/'); |
| 1992 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 1993 | |
Linus Torvalds | 36126f8 | 2012-05-26 10:43:17 -0700 | [diff] [blame] | 1994 | adata = prep_zero_mask(a, adata, &constants); |
| 1995 | bdata = prep_zero_mask(b, bdata, &constants); |
Linus Torvalds | 36126f8 | 2012-05-26 10:43:17 -0700 | [diff] [blame] | 1996 | mask = create_zero_mask(adata | bdata); |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1997 | x ^= a & zero_bytemask(mask); |
Linus Torvalds | 36126f8 | 2012-05-26 10:43:17 -0700 | [diff] [blame] | 1998 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 1999 | return hashlen_create(fold_hash(x, y), len + find_zero(mask)); |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 2000 | } |
| 2001 | |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 2002 | #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 2003 | |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2004 | /* Return the hash of a string of known length */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2005 | unsigned int full_name_hash(const void *salt, const char *name, unsigned int len) |
Linus Torvalds | 0145acc | 2012-03-02 14:32:59 -0800 | [diff] [blame] | 2006 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2007 | unsigned long hash = init_name_hash(salt); |
Linus Torvalds | 0145acc | 2012-03-02 14:32:59 -0800 | [diff] [blame] | 2008 | while (len--) |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2009 | hash = partial_name_hash((unsigned char)*name++, hash); |
Linus Torvalds | 0145acc | 2012-03-02 14:32:59 -0800 | [diff] [blame] | 2010 | return end_name_hash(hash); |
| 2011 | } |
Linus Torvalds | ae942ae | 2012-03-02 19:40:57 -0800 | [diff] [blame] | 2012 | EXPORT_SYMBOL(full_name_hash); |
Linus Torvalds | 0145acc | 2012-03-02 14:32:59 -0800 | [diff] [blame] | 2013 | |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2014 | /* Return the "hash_len" (hash and length) of a null-terminated string */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2015 | u64 hashlen_string(const void *salt, const char *name) |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2016 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2017 | unsigned long hash = init_name_hash(salt); |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2018 | unsigned long len = 0, c; |
| 2019 | |
| 2020 | c = (unsigned char)*name; |
George Spelvin | e0ab7af | 2016-05-29 08:05:56 -0400 | [diff] [blame] | 2021 | while (c) { |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2022 | len++; |
| 2023 | hash = partial_name_hash(c, hash); |
| 2024 | c = (unsigned char)name[len]; |
George Spelvin | e0ab7af | 2016-05-29 08:05:56 -0400 | [diff] [blame] | 2025 | } |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2026 | return hashlen_create(end_name_hash(hash), len); |
| 2027 | } |
George Spelvin | f2a031b | 2016-05-29 01:26:41 -0400 | [diff] [blame] | 2028 | EXPORT_SYMBOL(hashlen_string); |
George Spelvin | fcfd2fb | 2016-05-20 08:41:37 -0400 | [diff] [blame] | 2029 | |
Linus Torvalds | 3ddcd05 | 2011-08-06 22:45:50 -0700 | [diff] [blame] | 2030 | /* |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2031 | * We know there's a real path component here of at least |
| 2032 | * one character. |
| 2033 | */ |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2034 | static inline u64 hash_name(const void *salt, const char *name) |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2035 | { |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2036 | unsigned long hash = init_name_hash(salt); |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2037 | unsigned long len = 0, c; |
| 2038 | |
| 2039 | c = (unsigned char)*name; |
| 2040 | do { |
| 2041 | len++; |
| 2042 | hash = partial_name_hash(c, hash); |
| 2043 | c = (unsigned char)name[len]; |
| 2044 | } while (c && c != '/'); |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2045 | return hashlen_create(end_name_hash(hash), len); |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2046 | } |
| 2047 | |
Linus Torvalds | bfcfaa7 | 2012-03-06 11:16:17 -0800 | [diff] [blame] | 2048 | #endif |
| 2049 | |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2050 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2051 | * Name resolution. |
Prasanna Meda | ea3834d | 2005-04-29 16:00:17 +0100 | [diff] [blame] | 2052 | * This is the basic name resolution function, turning a pathname into |
| 2053 | * the final dentry. We expect 'base' to be positive and a directory. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2054 | * |
Prasanna Meda | ea3834d | 2005-04-29 16:00:17 +0100 | [diff] [blame] | 2055 | * Returns 0 and nd will have valid dentry and mnt on success. |
| 2056 | * Returns error and drops reference to input namei data on failure. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2057 | */ |
Al Viro | 6de88d7 | 2009-08-09 01:41:57 +0400 | [diff] [blame] | 2058 | static int link_path_walk(const char *name, struct nameidata *nd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2059 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2060 | int err; |
Al Viro | 32cd746 | 2015-04-18 20:30:49 -0400 | [diff] [blame] | 2061 | |
Al Viro | 9b5858e | 2018-07-09 16:33:23 -0400 | [diff] [blame] | 2062 | if (IS_ERR(name)) |
| 2063 | return PTR_ERR(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2064 | while (*name=='/') |
| 2065 | name++; |
| 2066 | if (!*name) |
Al Viro | 9e18f10 | 2015-04-18 20:44:34 -0400 | [diff] [blame] | 2067 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2068 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2069 | /* At this point we know we have a real path component. */ |
| 2070 | for(;;) { |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2071 | u64 hash_len; |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2072 | int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2073 | |
Al Viro | 52094c8 | 2011-02-21 21:34:47 -0500 | [diff] [blame] | 2074 | err = may_lookup(nd); |
George Spelvin | 2a18da7a | 2016-05-23 07:43:58 -0400 | [diff] [blame] | 2075 | if (err) |
Al Viro | 3595e23 | 2015-05-09 16:54:45 -0400 | [diff] [blame] | 2076 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2077 | |
Linus Torvalds | 8387ff2 | 2016-06-10 07:51:30 -0700 | [diff] [blame] | 2078 | hash_len = hash_name(nd->path.dentry, name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2079 | |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2080 | type = LAST_NORM; |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2081 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2082 | case 2: |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2083 | if (name[1] == '.') { |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2084 | type = LAST_DOTDOT; |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 2085 | nd->flags |= LOOKUP_JUMPED; |
| 2086 | } |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2087 | break; |
| 2088 | case 1: |
| 2089 | type = LAST_DOT; |
| 2090 | } |
Al Viro | 5a202bc | 2011-03-08 14:17:44 -0500 | [diff] [blame] | 2091 | if (likely(type == LAST_NORM)) { |
| 2092 | struct dentry *parent = nd->path.dentry; |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 2093 | nd->flags &= ~LOOKUP_JUMPED; |
Al Viro | 5a202bc | 2011-03-08 14:17:44 -0500 | [diff] [blame] | 2094 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
James Hogan | a060dc5 | 2014-09-16 13:07:35 +0100 | [diff] [blame] | 2095 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
Linus Torvalds | da53be1 | 2013-05-21 15:22:44 -0700 | [diff] [blame] | 2096 | err = parent->d_op->d_hash(parent, &this); |
Al Viro | 5a202bc | 2011-03-08 14:17:44 -0500 | [diff] [blame] | 2097 | if (err < 0) |
Al Viro | 3595e23 | 2015-05-09 16:54:45 -0400 | [diff] [blame] | 2098 | return err; |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2099 | hash_len = this.hash_len; |
| 2100 | name = this.name; |
Al Viro | 5a202bc | 2011-03-08 14:17:44 -0500 | [diff] [blame] | 2101 | } |
| 2102 | } |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2103 | |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2104 | nd->last.hash_len = hash_len; |
| 2105 | nd->last.name = name; |
Al Viro | 5f4a6a6 | 2013-01-24 18:04:22 -0500 | [diff] [blame] | 2106 | nd->last_type = type; |
| 2107 | |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2108 | name += hashlen_len(hash_len); |
| 2109 | if (!*name) |
Al Viro | bdf6cbf | 2015-04-18 20:21:40 -0400 | [diff] [blame] | 2110 | goto OK; |
Linus Torvalds | 200e9ef | 2012-03-02 14:49:24 -0800 | [diff] [blame] | 2111 | /* |
| 2112 | * If it wasn't NUL, we know it was '/'. Skip that |
| 2113 | * slash, and continue until no more slashes. |
| 2114 | */ |
| 2115 | do { |
Linus Torvalds | d6bb3e9 | 2014-09-15 10:51:07 -0700 | [diff] [blame] | 2116 | name++; |
| 2117 | } while (unlikely(*name == '/')); |
Al Viro | 8620c23 | 2015-05-04 08:58:35 -0400 | [diff] [blame] | 2118 | if (unlikely(!*name)) { |
| 2119 | OK: |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2120 | /* pathname body, done */ |
Al Viro | 8620c23 | 2015-05-04 08:58:35 -0400 | [diff] [blame] | 2121 | if (!nd->depth) |
| 2122 | return 0; |
| 2123 | name = nd->stack[nd->depth - 1].name; |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2124 | /* trailing symlink, done */ |
Al Viro | 8620c23 | 2015-05-04 08:58:35 -0400 | [diff] [blame] | 2125 | if (!name) |
| 2126 | return 0; |
| 2127 | /* last component of nested symlink */ |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 2128 | err = walk_component(nd, WALK_FOLLOW); |
Al Viro | 1c4ff1a | 2016-11-14 01:39:36 -0500 | [diff] [blame] | 2129 | } else { |
| 2130 | /* not the last component */ |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 2131 | err = walk_component(nd, WALK_FOLLOW | WALK_MORE); |
Al Viro | 8620c23 | 2015-05-04 08:58:35 -0400 | [diff] [blame] | 2132 | } |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 2133 | if (err < 0) |
Al Viro | 3595e23 | 2015-05-09 16:54:45 -0400 | [diff] [blame] | 2134 | return err; |
Al Viro | fe479a5 | 2011-02-22 15:10:03 -0500 | [diff] [blame] | 2135 | |
Al Viro | ce57dfc | 2011-03-13 19:58:58 -0400 | [diff] [blame] | 2136 | if (err) { |
Al Viro | 626de99 | 2015-05-04 18:26:59 -0400 | [diff] [blame] | 2137 | const char *s = get_link(nd); |
Al Viro | 5a46027 | 2015-04-17 23:44:45 -0400 | [diff] [blame] | 2138 | |
Viresh Kumar | a1c8368 | 2015-08-12 15:59:44 +0530 | [diff] [blame] | 2139 | if (IS_ERR(s)) |
Al Viro | 3595e23 | 2015-05-09 16:54:45 -0400 | [diff] [blame] | 2140 | return PTR_ERR(s); |
Al Viro | d40bcc0 | 2015-04-18 20:03:03 -0400 | [diff] [blame] | 2141 | err = 0; |
| 2142 | if (unlikely(!s)) { |
| 2143 | /* jumped */ |
Al Viro | b9ff442 | 2015-05-02 20:19:23 -0400 | [diff] [blame] | 2144 | put_link(nd); |
Al Viro | d40bcc0 | 2015-04-18 20:03:03 -0400 | [diff] [blame] | 2145 | } else { |
Al Viro | fab51e8 | 2015-05-10 11:01:00 -0400 | [diff] [blame] | 2146 | nd->stack[nd->depth - 1].name = name; |
| 2147 | name = s; |
| 2148 | continue; |
Al Viro | d40bcc0 | 2015-04-18 20:03:03 -0400 | [diff] [blame] | 2149 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2150 | } |
Al Viro | 97242f9 | 2015-08-01 19:59:28 -0400 | [diff] [blame] | 2151 | if (unlikely(!d_can_lookup(nd->path.dentry))) { |
| 2152 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 2153 | if (unlazy_walk(nd)) |
Al Viro | 97242f9 | 2015-08-01 19:59:28 -0400 | [diff] [blame] | 2154 | return -ECHILD; |
| 2155 | } |
Al Viro | 3595e23 | 2015-05-09 16:54:45 -0400 | [diff] [blame] | 2156 | return -ENOTDIR; |
Al Viro | 97242f9 | 2015-08-01 19:59:28 -0400 | [diff] [blame] | 2157 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2158 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2159 | } |
| 2160 | |
Al Viro | edc2b1d | 2018-07-09 16:27:23 -0400 | [diff] [blame] | 2161 | /* must be paired with terminate_walk() */ |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2162 | static const char *path_init(struct nameidata *nd, unsigned flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2163 | { |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2164 | const char *s = nd->name->name; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2165 | |
Linus Torvalds | c0eb027 | 2017-04-02 17:10:08 -0700 | [diff] [blame] | 2166 | if (!*s) |
| 2167 | flags &= ~LOOKUP_RCU; |
Al Viro | edc2b1d | 2018-07-09 16:27:23 -0400 | [diff] [blame] | 2168 | if (flags & LOOKUP_RCU) |
| 2169 | rcu_read_lock(); |
Linus Torvalds | c0eb027 | 2017-04-02 17:10:08 -0700 | [diff] [blame] | 2170 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2171 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ |
Al Viro | 980f3ea | 2014-11-20 14:20:24 -0500 | [diff] [blame] | 2172 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2173 | nd->depth = 0; |
Al Viro | 5b6ca02 | 2011-03-09 23:04:47 -0500 | [diff] [blame] | 2174 | if (flags & LOOKUP_ROOT) { |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 2175 | struct dentry *root = nd->root.dentry; |
| 2176 | struct inode *inode = root->d_inode; |
Al Viro | 9389386 | 2017-04-15 17:29:14 -0400 | [diff] [blame] | 2177 | if (*s && unlikely(!d_can_lookup(root))) |
| 2178 | return ERR_PTR(-ENOTDIR); |
Al Viro | 5b6ca02 | 2011-03-09 23:04:47 -0500 | [diff] [blame] | 2179 | nd->path = nd->root; |
| 2180 | nd->inode = inode; |
| 2181 | if (flags & LOOKUP_RCU) { |
Al Viro | 5b6ca02 | 2011-03-09 23:04:47 -0500 | [diff] [blame] | 2182 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
Al Viro | 8f47a016 | 2015-05-09 19:02:01 -0400 | [diff] [blame] | 2183 | nd->root_seq = nd->seq; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2184 | nd->m_seq = read_seqbegin(&mount_lock); |
Al Viro | 5b6ca02 | 2011-03-09 23:04:47 -0500 | [diff] [blame] | 2185 | } else { |
| 2186 | path_get(&nd->path); |
| 2187 | } |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2188 | return s; |
Al Viro | 5b6ca02 | 2011-03-09 23:04:47 -0500 | [diff] [blame] | 2189 | } |
| 2190 | |
Al Viro | 2a73787 | 2009-04-07 11:49:53 -0400 | [diff] [blame] | 2191 | nd->root.mnt = NULL; |
Al Viro | 248fb5b | 2015-12-05 20:51:58 -0500 | [diff] [blame] | 2192 | nd->path.mnt = NULL; |
| 2193 | nd->path.dentry = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2194 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 2195 | nd->m_seq = read_seqbegin(&mount_lock); |
Al Viro | fd2f7cb | 2015-02-22 20:07:13 -0500 | [diff] [blame] | 2196 | if (*s == '/') { |
Al Viro | 9e6697e | 2015-12-05 20:07:21 -0500 | [diff] [blame] | 2197 | set_root(nd); |
Al Viro | 248fb5b | 2015-12-05 20:51:58 -0500 | [diff] [blame] | 2198 | if (likely(!nd_jump_root(nd))) |
Al Viro | ef55d91 | 2015-12-05 20:25:06 -0500 | [diff] [blame] | 2199 | return s; |
Al Viro | ef55d91 | 2015-12-05 20:25:06 -0500 | [diff] [blame] | 2200 | return ERR_PTR(-ECHILD); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2201 | } else if (nd->dfd == AT_FDCWD) { |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2202 | if (flags & LOOKUP_RCU) { |
| 2203 | struct fs_struct *fs = current->fs; |
| 2204 | unsigned seq; |
| 2205 | |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2206 | do { |
| 2207 | seq = read_seqcount_begin(&fs->seq); |
| 2208 | nd->path = fs->pwd; |
Al Viro | ef55d91 | 2015-12-05 20:25:06 -0500 | [diff] [blame] | 2209 | nd->inode = nd->path.dentry->d_inode; |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2210 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
| 2211 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 2212 | } else { |
| 2213 | get_fs_pwd(current->fs, &nd->path); |
Al Viro | ef55d91 | 2015-12-05 20:25:06 -0500 | [diff] [blame] | 2214 | nd->inode = nd->path.dentry->d_inode; |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2215 | } |
Al Viro | ef55d91 | 2015-12-05 20:25:06 -0500 | [diff] [blame] | 2216 | return s; |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2217 | } else { |
Jeff Layton | 582aa64 | 2012-12-11 08:56:16 -0500 | [diff] [blame] | 2218 | /* Caller must check execute permissions on the starting path component */ |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2219 | struct fd f = fdget_raw(nd->dfd); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2220 | struct dentry *dentry; |
| 2221 | |
Al Viro | 2903ff0 | 2012-08-28 12:52:22 -0400 | [diff] [blame] | 2222 | if (!f.file) |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2223 | return ERR_PTR(-EBADF); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2224 | |
Al Viro | 2903ff0 | 2012-08-28 12:52:22 -0400 | [diff] [blame] | 2225 | dentry = f.file->f_path.dentry; |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2226 | |
Al Viro | edc2b1d | 2018-07-09 16:27:23 -0400 | [diff] [blame] | 2227 | if (*s && unlikely(!d_can_lookup(dentry))) { |
| 2228 | fdput(f); |
| 2229 | return ERR_PTR(-ENOTDIR); |
Al Viro | f52e0c1 | 2011-03-14 18:56:51 -0400 | [diff] [blame] | 2230 | } |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2231 | |
Al Viro | 2903ff0 | 2012-08-28 12:52:22 -0400 | [diff] [blame] | 2232 | nd->path = f.file->f_path; |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2233 | if (flags & LOOKUP_RCU) { |
Al Viro | 34a26b9 | 2015-05-11 08:05:05 -0400 | [diff] [blame] | 2234 | nd->inode = nd->path.dentry->d_inode; |
| 2235 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2236 | } else { |
Al Viro | 2903ff0 | 2012-08-28 12:52:22 -0400 | [diff] [blame] | 2237 | path_get(&nd->path); |
Al Viro | 34a26b9 | 2015-05-11 08:05:05 -0400 | [diff] [blame] | 2238 | nd->inode = nd->path.dentry->d_inode; |
Al Viro | e41f7d4 | 2011-02-22 14:02:58 -0500 | [diff] [blame] | 2239 | } |
Al Viro | 34a26b9 | 2015-05-11 08:05:05 -0400 | [diff] [blame] | 2240 | fdput(f); |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2241 | return s; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2242 | } |
Al Viro | 9b4a9b1 | 2009-04-07 11:44:16 -0400 | [diff] [blame] | 2243 | } |
| 2244 | |
Al Viro | 3bdba28 | 2015-05-08 17:37:07 -0400 | [diff] [blame] | 2245 | static const char *trailing_symlink(struct nameidata *nd) |
Al Viro | 95fa25d | 2015-04-22 13:46:57 -0400 | [diff] [blame] | 2246 | { |
| 2247 | const char *s; |
Al Viro | fec2fa2 | 2015-05-06 15:58:18 -0400 | [diff] [blame] | 2248 | int error = may_follow_link(nd); |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2249 | if (unlikely(error)) |
Al Viro | 3bdba28 | 2015-05-08 17:37:07 -0400 | [diff] [blame] | 2250 | return ERR_PTR(error); |
Al Viro | 95fa25d | 2015-04-22 13:46:57 -0400 | [diff] [blame] | 2251 | nd->flags |= LOOKUP_PARENT; |
Al Viro | fab51e8 | 2015-05-10 11:01:00 -0400 | [diff] [blame] | 2252 | nd->stack[0].name = NULL; |
Al Viro | 3b2e7f7 | 2015-04-19 00:53:50 -0400 | [diff] [blame] | 2253 | s = get_link(nd); |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2254 | return s ? s : ""; |
Al Viro | 95fa25d | 2015-04-22 13:46:57 -0400 | [diff] [blame] | 2255 | } |
| 2256 | |
Al Viro | caa85634 | 2015-04-22 17:52:47 -0400 | [diff] [blame] | 2257 | static inline int lookup_last(struct nameidata *nd) |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2258 | { |
| 2259 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) |
| 2260 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
| 2261 | |
| 2262 | nd->flags &= ~LOOKUP_PARENT; |
Al Viro | 1c4ff1a | 2016-11-14 01:39:36 -0500 | [diff] [blame] | 2263 | return walk_component(nd, 0); |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2264 | } |
| 2265 | |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 2266 | static int handle_lookup_down(struct nameidata *nd) |
| 2267 | { |
| 2268 | struct path path = nd->path; |
| 2269 | struct inode *inode = nd->inode; |
| 2270 | unsigned seq = nd->seq; |
| 2271 | int err; |
| 2272 | |
| 2273 | if (nd->flags & LOOKUP_RCU) { |
| 2274 | /* |
| 2275 | * don't bother with unlazy_walk on failure - we are |
| 2276 | * at the very beginning of walk, so we lose nothing |
| 2277 | * if we simply redo everything in non-RCU mode |
| 2278 | */ |
| 2279 | if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq))) |
| 2280 | return -ECHILD; |
| 2281 | } else { |
| 2282 | dget(path.dentry); |
| 2283 | err = follow_managed(&path, nd); |
| 2284 | if (unlikely(err < 0)) |
| 2285 | return err; |
| 2286 | inode = d_backing_inode(path.dentry); |
| 2287 | seq = 0; |
| 2288 | } |
| 2289 | path_to_nameidata(&path, nd); |
| 2290 | nd->inode = inode; |
| 2291 | nd->seq = seq; |
| 2292 | return 0; |
| 2293 | } |
| 2294 | |
Al Viro | 9b4a9b1 | 2009-04-07 11:44:16 -0400 | [diff] [blame] | 2295 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2296 | static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) |
Al Viro | 9b4a9b1 | 2009-04-07 11:44:16 -0400 | [diff] [blame] | 2297 | { |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2298 | const char *s = path_init(nd, flags); |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2299 | int err; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2300 | |
Al Viro | 9b5858e | 2018-07-09 16:33:23 -0400 | [diff] [blame] | 2301 | if (unlikely(flags & LOOKUP_DOWN) && !IS_ERR(s)) { |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 2302 | err = handle_lookup_down(nd); |
Al Viro | 5f336e7 | 2018-07-09 16:38:06 -0400 | [diff] [blame] | 2303 | if (unlikely(err < 0)) |
| 2304 | s = ERR_PTR(err); |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 2305 | } |
| 2306 | |
Al Viro | 3bdba28 | 2015-05-08 17:37:07 -0400 | [diff] [blame] | 2307 | while (!(err = link_path_walk(s, nd)) |
| 2308 | && ((err = lookup_last(nd)) > 0)) { |
| 2309 | s = trailing_symlink(nd); |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2310 | } |
Al Viro | 9f1fafe | 2011-03-25 11:00:12 -0400 | [diff] [blame] | 2311 | if (!err) |
| 2312 | err = complete_walk(nd); |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2313 | |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2314 | if (!err && nd->flags & LOOKUP_DIRECTORY) |
| 2315 | if (!d_can_lookup(nd->path.dentry)) |
Al Viro | bd23a53 | 2011-03-23 09:56:30 -0400 | [diff] [blame] | 2316 | err = -ENOTDIR; |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 2317 | if (!err) { |
| 2318 | *path = nd->path; |
| 2319 | nd->path.mnt = NULL; |
| 2320 | nd->path.dentry = NULL; |
| 2321 | } |
| 2322 | terminate_walk(nd); |
Al Viro | bd92d7f | 2011-03-14 19:54:59 -0400 | [diff] [blame] | 2323 | return err; |
Al Viro | ee0827c | 2011-02-21 23:38:09 -0500 | [diff] [blame] | 2324 | } |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 2325 | |
David Howells | 31d921c | 2018-11-01 23:07:24 +0000 | [diff] [blame] | 2326 | int filename_lookup(int dfd, struct filename *name, unsigned flags, |
| 2327 | struct path *path, struct path *root) |
Jeff Layton | 873f1ee | 2012-10-10 15:25:29 -0400 | [diff] [blame] | 2328 | { |
Al Viro | 894bc8c | 2015-05-02 07:16:16 -0400 | [diff] [blame] | 2329 | int retval; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2330 | struct nameidata nd; |
Al Viro | abc9f5b | 2015-05-12 16:53:42 -0400 | [diff] [blame] | 2331 | if (IS_ERR(name)) |
| 2332 | return PTR_ERR(name); |
Al Viro | 9ad1aaa | 2015-05-12 16:44:39 -0400 | [diff] [blame] | 2333 | if (unlikely(root)) { |
| 2334 | nd.root = *root; |
| 2335 | flags |= LOOKUP_ROOT; |
| 2336 | } |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2337 | set_nameidata(&nd, dfd, name); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2338 | retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); |
Jeff Layton | 873f1ee | 2012-10-10 15:25:29 -0400 | [diff] [blame] | 2339 | if (unlikely(retval == -ECHILD)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2340 | retval = path_lookupat(&nd, flags, path); |
Jeff Layton | 873f1ee | 2012-10-10 15:25:29 -0400 | [diff] [blame] | 2341 | if (unlikely(retval == -ESTALE)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2342 | retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); |
Jeff Layton | 873f1ee | 2012-10-10 15:25:29 -0400 | [diff] [blame] | 2343 | |
| 2344 | if (likely(!retval)) |
Al Viro | ff0ebee | 2019-07-14 12:18:05 -0400 | [diff] [blame] | 2345 | audit_inode(name, path->dentry, 0); |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2346 | restore_nameidata(); |
Al Viro | e4bd1c1 | 2015-05-12 16:40:39 -0400 | [diff] [blame] | 2347 | putname(name); |
Jeff Layton | 873f1ee | 2012-10-10 15:25:29 -0400 | [diff] [blame] | 2348 | return retval; |
| 2349 | } |
| 2350 | |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2351 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2352 | static int path_parentat(struct nameidata *nd, unsigned flags, |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2353 | struct path *parent) |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2354 | { |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2355 | const char *s = path_init(nd, flags); |
Al Viro | 9b5858e | 2018-07-09 16:33:23 -0400 | [diff] [blame] | 2356 | int err = link_path_walk(s, nd); |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2357 | if (!err) |
| 2358 | err = complete_walk(nd); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2359 | if (!err) { |
| 2360 | *parent = nd->path; |
| 2361 | nd->path.mnt = NULL; |
| 2362 | nd->path.dentry = NULL; |
| 2363 | } |
| 2364 | terminate_walk(nd); |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2365 | return err; |
| 2366 | } |
| 2367 | |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2368 | static struct filename *filename_parentat(int dfd, struct filename *name, |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2369 | unsigned int flags, struct path *parent, |
| 2370 | struct qstr *last, int *type) |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2371 | { |
| 2372 | int retval; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2373 | struct nameidata nd; |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2374 | |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2375 | if (IS_ERR(name)) |
| 2376 | return name; |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2377 | set_nameidata(&nd, dfd, name); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2378 | retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2379 | if (unlikely(retval == -ECHILD)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2380 | retval = path_parentat(&nd, flags, parent); |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2381 | if (unlikely(retval == -ESTALE)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2382 | retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2383 | if (likely(!retval)) { |
| 2384 | *last = nd.last; |
| 2385 | *type = nd.last_type; |
Al Viro | c9b07ea | 2019-07-14 13:22:27 -0400 | [diff] [blame] | 2386 | audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2387 | } else { |
| 2388 | putname(name); |
| 2389 | name = ERR_PTR(retval); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2390 | } |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2391 | restore_nameidata(); |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2392 | return name; |
Al Viro | 8bcb77f | 2015-05-08 16:59:20 -0400 | [diff] [blame] | 2393 | } |
| 2394 | |
Al Viro | 79714f7 | 2012-06-15 03:01:42 +0400 | [diff] [blame] | 2395 | /* does lookup, returns the object with parent locked */ |
| 2396 | struct dentry *kern_path_locked(const char *name, struct path *path) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2397 | { |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2398 | struct filename *filename; |
| 2399 | struct dentry *d; |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2400 | struct qstr last; |
| 2401 | int type; |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 2402 | |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2403 | filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, |
| 2404 | &last, &type); |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 2405 | if (IS_ERR(filename)) |
| 2406 | return ERR_CAST(filename); |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2407 | if (unlikely(type != LAST_NORM)) { |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2408 | path_put(path); |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 2409 | putname(filename); |
| 2410 | return ERR_PTR(-EINVAL); |
Al Viro | 79714f7 | 2012-06-15 03:01:42 +0400 | [diff] [blame] | 2411 | } |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2412 | inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2413 | d = __lookup_hash(&last, path->dentry, 0); |
Al Viro | 79714f7 | 2012-06-15 03:01:42 +0400 | [diff] [blame] | 2414 | if (IS_ERR(d)) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2415 | inode_unlock(path->dentry->d_inode); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 2416 | path_put(path); |
Al Viro | 79714f7 | 2012-06-15 03:01:42 +0400 | [diff] [blame] | 2417 | } |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 2418 | putname(filename); |
Al Viro | 79714f7 | 2012-06-15 03:01:42 +0400 | [diff] [blame] | 2419 | return d; |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 2420 | } |
| 2421 | |
Al Viro | d181146 | 2008-08-02 00:49:18 -0400 | [diff] [blame] | 2422 | int kern_path(const char *name, unsigned int flags, struct path *path) |
| 2423 | { |
Al Viro | abc9f5b | 2015-05-12 16:53:42 -0400 | [diff] [blame] | 2424 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
| 2425 | flags, path, NULL); |
Al Viro | d181146 | 2008-08-02 00:49:18 -0400 | [diff] [blame] | 2426 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2427 | EXPORT_SYMBOL(kern_path); |
Al Viro | d181146 | 2008-08-02 00:49:18 -0400 | [diff] [blame] | 2428 | |
Josef 'Jeff' Sipek | 16f1820 | 2007-07-19 01:48:18 -0700 | [diff] [blame] | 2429 | /** |
| 2430 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair |
| 2431 | * @dentry: pointer to dentry of the base directory |
| 2432 | * @mnt: pointer to vfs mount of the base directory |
| 2433 | * @name: pointer to file name |
| 2434 | * @flags: lookup flags |
Al Viro | e0a0124 | 2011-06-27 17:00:37 -0400 | [diff] [blame] | 2435 | * @path: pointer to struct path to fill |
Josef 'Jeff' Sipek | 16f1820 | 2007-07-19 01:48:18 -0700 | [diff] [blame] | 2436 | */ |
| 2437 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, |
| 2438 | const char *name, unsigned int flags, |
Al Viro | e0a0124 | 2011-06-27 17:00:37 -0400 | [diff] [blame] | 2439 | struct path *path) |
Josef 'Jeff' Sipek | 16f1820 | 2007-07-19 01:48:18 -0700 | [diff] [blame] | 2440 | { |
Al Viro | 9ad1aaa | 2015-05-12 16:44:39 -0400 | [diff] [blame] | 2441 | struct path root = {.mnt = mnt, .dentry = dentry}; |
Al Viro | 9ad1aaa | 2015-05-12 16:44:39 -0400 | [diff] [blame] | 2442 | /* the first argument of filename_lookup() is ignored with root */ |
Al Viro | abc9f5b | 2015-05-12 16:53:42 -0400 | [diff] [blame] | 2443 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
| 2444 | flags , path, &root); |
Josef 'Jeff' Sipek | 16f1820 | 2007-07-19 01:48:18 -0700 | [diff] [blame] | 2445 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2446 | EXPORT_SYMBOL(vfs_path_lookup); |
Josef 'Jeff' Sipek | 16f1820 | 2007-07-19 01:48:18 -0700 | [diff] [blame] | 2447 | |
Al Viro | 3c95f0d | 2018-04-06 16:32:38 -0400 | [diff] [blame] | 2448 | static int lookup_one_len_common(const char *name, struct dentry *base, |
| 2449 | int len, struct qstr *this) |
| 2450 | { |
| 2451 | this->name = name; |
| 2452 | this->len = len; |
| 2453 | this->hash = full_name_hash(base, name, len); |
| 2454 | if (!len) |
| 2455 | return -EACCES; |
| 2456 | |
| 2457 | if (unlikely(name[0] == '.')) { |
| 2458 | if (len < 2 || (len == 2 && name[1] == '.')) |
| 2459 | return -EACCES; |
| 2460 | } |
| 2461 | |
| 2462 | while (len--) { |
| 2463 | unsigned int c = *(const unsigned char *)name++; |
| 2464 | if (c == '/' || c == '\0') |
| 2465 | return -EACCES; |
| 2466 | } |
| 2467 | /* |
| 2468 | * See if the low-level filesystem might want |
| 2469 | * to use its own hash.. |
| 2470 | */ |
| 2471 | if (base->d_flags & DCACHE_OP_HASH) { |
| 2472 | int err = base->d_op->d_hash(base, this); |
| 2473 | if (err < 0) |
| 2474 | return err; |
| 2475 | } |
| 2476 | |
| 2477 | return inode_permission(base->d_inode, MAY_EXEC); |
| 2478 | } |
| 2479 | |
Christoph Hellwig | eead191 | 2007-10-16 23:25:38 -0700 | [diff] [blame] | 2480 | /** |
David Howells | 0da0b7f | 2018-06-15 15:19:22 +0100 | [diff] [blame] | 2481 | * try_lookup_one_len - filesystem helper to lookup single pathname component |
| 2482 | * @name: pathname component to lookup |
| 2483 | * @base: base directory to lookup from |
| 2484 | * @len: maximum length @len should be interpreted to |
| 2485 | * |
| 2486 | * Look up a dentry by name in the dcache, returning NULL if it does not |
| 2487 | * currently exist. The function does not try to create a dentry. |
| 2488 | * |
| 2489 | * Note that this routine is purely a helper for filesystem usage and should |
| 2490 | * not be called by generic code. |
| 2491 | * |
| 2492 | * The caller must hold base->i_mutex. |
| 2493 | */ |
| 2494 | struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len) |
| 2495 | { |
| 2496 | struct qstr this; |
| 2497 | int err; |
| 2498 | |
| 2499 | WARN_ON_ONCE(!inode_is_locked(base->d_inode)); |
| 2500 | |
| 2501 | err = lookup_one_len_common(name, base, len, &this); |
| 2502 | if (err) |
| 2503 | return ERR_PTR(err); |
| 2504 | |
| 2505 | return lookup_dcache(&this, base, 0); |
| 2506 | } |
| 2507 | EXPORT_SYMBOL(try_lookup_one_len); |
| 2508 | |
| 2509 | /** |
Randy Dunlap | a6b9191 | 2008-03-19 17:01:00 -0700 | [diff] [blame] | 2510 | * lookup_one_len - filesystem helper to lookup single pathname component |
Christoph Hellwig | eead191 | 2007-10-16 23:25:38 -0700 | [diff] [blame] | 2511 | * @name: pathname component to lookup |
| 2512 | * @base: base directory to lookup from |
| 2513 | * @len: maximum length @len should be interpreted to |
| 2514 | * |
Randy Dunlap | a6b9191 | 2008-03-19 17:01:00 -0700 | [diff] [blame] | 2515 | * Note that this routine is purely a helper for filesystem usage and should |
Al Viro | 9e7543e | 2015-02-23 02:49:48 -0500 | [diff] [blame] | 2516 | * not be called by generic code. |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2517 | * |
| 2518 | * The caller must hold base->i_mutex. |
Christoph Hellwig | eead191 | 2007-10-16 23:25:38 -0700 | [diff] [blame] | 2519 | */ |
James Morris | 057f6c0 | 2007-04-26 00:12:05 -0700 | [diff] [blame] | 2520 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
| 2521 | { |
Al Viro | 8613a20 | 2018-04-06 16:45:33 -0400 | [diff] [blame] | 2522 | struct dentry *dentry; |
James Morris | 057f6c0 | 2007-04-26 00:12:05 -0700 | [diff] [blame] | 2523 | struct qstr this; |
Miklos Szeredi | cda309d | 2012-03-26 12:54:21 +0200 | [diff] [blame] | 2524 | int err; |
James Morris | 057f6c0 | 2007-04-26 00:12:05 -0700 | [diff] [blame] | 2525 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2526 | WARN_ON_ONCE(!inode_is_locked(base->d_inode)); |
David Woodhouse | 2f9092e | 2009-04-20 23:18:37 +0100 | [diff] [blame] | 2527 | |
Al Viro | 3c95f0d | 2018-04-06 16:32:38 -0400 | [diff] [blame] | 2528 | err = lookup_one_len_common(name, base, len, &this); |
Miklos Szeredi | cda309d | 2012-03-26 12:54:21 +0200 | [diff] [blame] | 2529 | if (err) |
| 2530 | return ERR_PTR(err); |
| 2531 | |
Al Viro | 8613a20 | 2018-04-06 16:45:33 -0400 | [diff] [blame] | 2532 | dentry = lookup_dcache(&this, base, 0); |
| 2533 | return dentry ? dentry : __lookup_slow(&this, base, 0); |
James Morris | 057f6c0 | 2007-04-26 00:12:05 -0700 | [diff] [blame] | 2534 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2535 | EXPORT_SYMBOL(lookup_one_len); |
James Morris | 057f6c0 | 2007-04-26 00:12:05 -0700 | [diff] [blame] | 2536 | |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2537 | /** |
| 2538 | * lookup_one_len_unlocked - filesystem helper to lookup single pathname component |
| 2539 | * @name: pathname component to lookup |
| 2540 | * @base: base directory to lookup from |
| 2541 | * @len: maximum length @len should be interpreted to |
| 2542 | * |
| 2543 | * Note that this routine is purely a helper for filesystem usage and should |
| 2544 | * not be called by generic code. |
| 2545 | * |
| 2546 | * Unlike lookup_one_len, it should be called without the parent |
| 2547 | * i_mutex held, and will take the i_mutex itself if necessary. |
| 2548 | */ |
| 2549 | struct dentry *lookup_one_len_unlocked(const char *name, |
| 2550 | struct dentry *base, int len) |
| 2551 | { |
| 2552 | struct qstr this; |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2553 | int err; |
Linus Torvalds | 20d00ee | 2016-07-29 12:17:52 -0700 | [diff] [blame] | 2554 | struct dentry *ret; |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2555 | |
Al Viro | 3c95f0d | 2018-04-06 16:32:38 -0400 | [diff] [blame] | 2556 | err = lookup_one_len_common(name, base, len, &this); |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2557 | if (err) |
| 2558 | return ERR_PTR(err); |
| 2559 | |
Linus Torvalds | 20d00ee | 2016-07-29 12:17:52 -0700 | [diff] [blame] | 2560 | ret = lookup_dcache(&this, base, 0); |
| 2561 | if (!ret) |
| 2562 | ret = lookup_slow(&this, base, 0); |
| 2563 | return ret; |
NeilBrown | bbddca8 | 2016-01-07 16:08:20 -0500 | [diff] [blame] | 2564 | } |
| 2565 | EXPORT_SYMBOL(lookup_one_len_unlocked); |
| 2566 | |
Eric W. Biederman | eedf265 | 2016-06-02 10:29:47 -0500 | [diff] [blame] | 2567 | #ifdef CONFIG_UNIX98_PTYS |
| 2568 | int path_pts(struct path *path) |
| 2569 | { |
| 2570 | /* Find something mounted on "pts" in the same directory as |
| 2571 | * the input path. |
| 2572 | */ |
| 2573 | struct dentry *child, *parent; |
| 2574 | struct qstr this; |
| 2575 | int ret; |
| 2576 | |
| 2577 | ret = path_parent_directory(path); |
| 2578 | if (ret) |
| 2579 | return ret; |
| 2580 | |
| 2581 | parent = path->dentry; |
| 2582 | this.name = "pts"; |
| 2583 | this.len = 3; |
| 2584 | child = d_hash_and_lookup(parent, &this); |
| 2585 | if (!child) |
| 2586 | return -ENOENT; |
| 2587 | |
| 2588 | path->dentry = child; |
| 2589 | dput(parent); |
| 2590 | follow_mount(path); |
| 2591 | return 0; |
| 2592 | } |
| 2593 | #endif |
| 2594 | |
Andy Whitcroft | 1fa1e7f | 2011-11-02 09:44:39 +0100 | [diff] [blame] | 2595 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
| 2596 | struct path *path, int *empty) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2597 | { |
Al Viro | abc9f5b | 2015-05-12 16:53:42 -0400 | [diff] [blame] | 2598 | return filename_lookup(dfd, getname_flags(name, flags, empty), |
| 2599 | flags, path, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2600 | } |
Al Viro | b853a16 | 2015-05-13 09:12:02 -0400 | [diff] [blame] | 2601 | EXPORT_SYMBOL(user_path_at_empty); |
Andy Whitcroft | 1fa1e7f | 2011-11-02 09:44:39 +0100 | [diff] [blame] | 2602 | |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2603 | /** |
Al Viro | 197df04 | 2013-09-08 14:03:27 -0400 | [diff] [blame] | 2604 | * mountpoint_last - look up last component for umount |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2605 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2606 | * |
| 2607 | * This is a special lookup_last function just for umount. In this case, we |
| 2608 | * need to resolve the path without doing any revalidation. |
| 2609 | * |
| 2610 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since |
| 2611 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, |
| 2612 | * in almost all cases, this lookup will be served out of the dcache. The only |
| 2613 | * cases where it won't are if nd->last refers to a symlink or the path is |
| 2614 | * bogus and it doesn't exist. |
| 2615 | * |
| 2616 | * Returns: |
| 2617 | * -error: if there was an error during lookup. This includes -ENOENT if the |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2618 | * lookup found a negative dentry. |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2619 | * |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2620 | * 0: if we successfully resolved nd->last and found it to not to be a |
| 2621 | * symlink that needs to be followed. |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2622 | * |
| 2623 | * 1: if we successfully resolved nd->last and found it to be a symlink |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2624 | * that needs to be followed. |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2625 | */ |
| 2626 | static int |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2627 | mountpoint_last(struct nameidata *nd) |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2628 | { |
| 2629 | int error = 0; |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2630 | struct dentry *dir = nd->path.dentry; |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2631 | struct path path; |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2632 | |
Al Viro | 3575952 | 2013-09-08 13:41:33 -0400 | [diff] [blame] | 2633 | /* If we're in rcuwalk, drop out of it to handle last component */ |
| 2634 | if (nd->flags & LOOKUP_RCU) { |
Al Viro | 4675ac3 | 2017-01-09 22:29:15 -0500 | [diff] [blame] | 2635 | if (unlazy_walk(nd)) |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2636 | return -ECHILD; |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2637 | } |
| 2638 | |
| 2639 | nd->flags &= ~LOOKUP_PARENT; |
| 2640 | |
| 2641 | if (unlikely(nd->last_type != LAST_NORM)) { |
| 2642 | error = handle_dots(nd, nd->last_type); |
Al Viro | 3575952 | 2013-09-08 13:41:33 -0400 | [diff] [blame] | 2643 | if (error) |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2644 | return error; |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2645 | path.dentry = dget(nd->path.dentry); |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 2646 | } else { |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2647 | path.dentry = d_lookup(dir, &nd->last); |
| 2648 | if (!path.dentry) { |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 2649 | /* |
| 2650 | * No cached dentry. Mounted dentries are pinned in the |
| 2651 | * cache, so that means that this dentry is probably |
| 2652 | * a symlink or the path doesn't actually point |
| 2653 | * to a mounted dentry. |
| 2654 | */ |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2655 | path.dentry = lookup_slow(&nd->last, dir, |
Al Viro | 949a852 | 2016-03-06 14:20:52 -0500 | [diff] [blame] | 2656 | nd->flags | LOOKUP_NO_REVAL); |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2657 | if (IS_ERR(path.dentry)) |
| 2658 | return PTR_ERR(path.dentry); |
Dave Jones | bcceeeb | 2013-09-10 17:04:25 -0400 | [diff] [blame] | 2659 | } |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2660 | } |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2661 | if (d_is_negative(path.dentry)) { |
| 2662 | dput(path.dentry); |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2663 | return -ENOENT; |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2664 | } |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2665 | path.mnt = nd->path.mnt; |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 2666 | return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0); |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2667 | } |
| 2668 | |
| 2669 | /** |
Al Viro | 197df04 | 2013-09-08 14:03:27 -0400 | [diff] [blame] | 2670 | * path_mountpoint - look up a path to be umounted |
Masanari Iida | 2a78b857 | 2015-09-09 15:39:23 -0700 | [diff] [blame] | 2671 | * @nd: lookup context |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2672 | * @flags: lookup flags |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2673 | * @path: pointer to container for result |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2674 | * |
| 2675 | * Look up the given name, but don't attempt to revalidate the last component. |
Randy Dunlap | 606d6fe | 2013-10-19 14:56:55 -0700 | [diff] [blame] | 2676 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2677 | */ |
| 2678 | static int |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2679 | path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2680 | { |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2681 | const char *s = path_init(nd, flags); |
Al Viro | 368ee9b | 2015-05-08 17:19:59 -0400 | [diff] [blame] | 2682 | int err; |
Al Viro | 9b5858e | 2018-07-09 16:33:23 -0400 | [diff] [blame] | 2683 | |
Al Viro | 3bdba28 | 2015-05-08 17:37:07 -0400 | [diff] [blame] | 2684 | while (!(err = link_path_walk(s, nd)) && |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2685 | (err = mountpoint_last(nd)) > 0) { |
Al Viro | 3bdba28 | 2015-05-08 17:37:07 -0400 | [diff] [blame] | 2686 | s = trailing_symlink(nd); |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2687 | } |
Al Viro | ba8f461 | 2016-11-14 00:40:33 -0500 | [diff] [blame] | 2688 | if (!err) { |
| 2689 | *path = nd->path; |
| 2690 | nd->path.mnt = NULL; |
| 2691 | nd->path.dentry = NULL; |
| 2692 | follow_mount(path); |
| 2693 | } |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 2694 | terminate_walk(nd); |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2695 | return err; |
| 2696 | } |
| 2697 | |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2698 | static int |
Al Viro | 668696d | 2015-02-22 19:44:00 -0500 | [diff] [blame] | 2699 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2700 | unsigned int flags) |
| 2701 | { |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2702 | struct nameidata nd; |
Al Viro | cbaab2d | 2015-01-22 02:49:00 -0500 | [diff] [blame] | 2703 | int error; |
Al Viro | 668696d | 2015-02-22 19:44:00 -0500 | [diff] [blame] | 2704 | if (IS_ERR(name)) |
| 2705 | return PTR_ERR(name); |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2706 | set_nameidata(&nd, dfd, name); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2707 | error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2708 | if (unlikely(error == -ECHILD)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2709 | error = path_mountpoint(&nd, flags, path); |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2710 | if (unlikely(error == -ESTALE)) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 2711 | error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2712 | if (likely(!error)) |
Al Viro | c9b07ea | 2019-07-14 13:22:27 -0400 | [diff] [blame] | 2713 | audit_inode(name, path->dentry, AUDIT_INODE_NOEVAL); |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 2714 | restore_nameidata(); |
Al Viro | 668696d | 2015-02-22 19:44:00 -0500 | [diff] [blame] | 2715 | putname(name); |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2716 | return error; |
| 2717 | } |
| 2718 | |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2719 | /** |
Al Viro | 197df04 | 2013-09-08 14:03:27 -0400 | [diff] [blame] | 2720 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2721 | * @dfd: directory file descriptor |
| 2722 | * @name: pathname from userland |
| 2723 | * @flags: lookup flags |
| 2724 | * @path: pointer to container to hold result |
| 2725 | * |
| 2726 | * A umount is a special case for path walking. We're not actually interested |
| 2727 | * in the inode in this situation, and ESTALE errors can be a problem. We |
| 2728 | * simply want track down the dentry and vfsmount attached at the mountpoint |
| 2729 | * and avoid revalidating the last component. |
| 2730 | * |
| 2731 | * Returns 0 and populates "path" on success. |
| 2732 | */ |
| 2733 | int |
Al Viro | 197df04 | 2013-09-08 14:03:27 -0400 | [diff] [blame] | 2734 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2735 | struct path *path) |
| 2736 | { |
Al Viro | cbaab2d | 2015-01-22 02:49:00 -0500 | [diff] [blame] | 2737 | return filename_mountpoint(dfd, getname(name), path, flags); |
Jeff Layton | 8033426 | 2013-07-26 06:23:25 -0400 | [diff] [blame] | 2738 | } |
| 2739 | |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2740 | int |
| 2741 | kern_path_mountpoint(int dfd, const char *name, struct path *path, |
| 2742 | unsigned int flags) |
| 2743 | { |
Al Viro | cbaab2d | 2015-01-22 02:49:00 -0500 | [diff] [blame] | 2744 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
Al Viro | 2d86465 | 2013-09-08 20:18:44 -0400 | [diff] [blame] | 2745 | } |
| 2746 | EXPORT_SYMBOL(kern_path_mountpoint); |
| 2747 | |
Miklos Szeredi | cbdf35b | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2748 | int __check_sticky(struct inode *dir, struct inode *inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2749 | { |
Eric W. Biederman | 8e96e3b | 2012-03-03 21:17:15 -0800 | [diff] [blame] | 2750 | kuid_t fsuid = current_fsuid(); |
David Howells | da9592e | 2008-11-14 10:39:05 +1100 | [diff] [blame] | 2751 | |
Eric W. Biederman | 8e96e3b | 2012-03-03 21:17:15 -0800 | [diff] [blame] | 2752 | if (uid_eq(inode->i_uid, fsuid)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2753 | return 0; |
Eric W. Biederman | 8e96e3b | 2012-03-03 21:17:15 -0800 | [diff] [blame] | 2754 | if (uid_eq(dir->i_uid, fsuid)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2755 | return 0; |
Andy Lutomirski | 23adbe1 | 2014-06-10 12:45:42 -0700 | [diff] [blame] | 2756 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2757 | } |
Miklos Szeredi | cbdf35b | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2758 | EXPORT_SYMBOL(__check_sticky); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2759 | |
| 2760 | /* |
| 2761 | * Check whether we can remove a link victim from directory dir, check |
| 2762 | * whether the type of victim is right. |
| 2763 | * 1. We can't do it if dir is read-only (done in permission()) |
| 2764 | * 2. We should have write and exec permissions on dir |
| 2765 | * 3. We can't remove anything from append-only dir |
| 2766 | * 4. We can't do anything with immutable dir (done in permission()) |
| 2767 | * 5. If the sticky bit on dir is set we should either |
| 2768 | * a. be owner of dir, or |
| 2769 | * b. be owner of victim, or |
| 2770 | * c. have CAP_FOWNER capability |
| 2771 | * 6. If the victim is append-only or immutable we can't do antyhing with |
| 2772 | * links pointing to it. |
Eric W. Biederman | 0bd23d09 | 2016-06-29 14:54:46 -0500 | [diff] [blame] | 2773 | * 7. If the victim has an unknown uid or gid we can't change the inode. |
| 2774 | * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. |
| 2775 | * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. |
| 2776 | * 10. We can't remove a root or mountpoint. |
| 2777 | * 11. We don't allow removal of NFS sillyrenamed files; it's handled by |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2778 | * nfs_async_unlink(). |
| 2779 | */ |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 2780 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2781 | { |
David Howells | 63afdfc | 2015-05-06 15:59:00 +0100 | [diff] [blame] | 2782 | struct inode *inode = d_backing_inode(victim); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2783 | int error; |
| 2784 | |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 2785 | if (d_is_negative(victim)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2786 | return -ENOENT; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 2787 | BUG_ON(!inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2788 | |
| 2789 | BUG_ON(victim->d_parent->d_inode != dir); |
Eric W. Biederman | 593d1ce | 2017-09-14 12:07:32 -0500 | [diff] [blame] | 2790 | |
| 2791 | /* Inode writeback is not safe when the uid or gid are invalid. */ |
| 2792 | if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid)) |
| 2793 | return -EOVERFLOW; |
| 2794 | |
Jeff Layton | 4fa6b5e | 2012-10-10 15:25:25 -0400 | [diff] [blame] | 2795 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2796 | |
Al Viro | f419a2e | 2008-07-22 00:07:17 -0400 | [diff] [blame] | 2797 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2798 | if (error) |
| 2799 | return error; |
| 2800 | if (IS_APPEND(dir)) |
| 2801 | return -EPERM; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 2802 | |
| 2803 | if (check_sticky(dir, inode) || IS_APPEND(inode) || |
Eric W. Biederman | 0bd23d09 | 2016-06-29 14:54:46 -0500 | [diff] [blame] | 2804 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2805 | return -EPERM; |
| 2806 | if (isdir) { |
Miklos Szeredi | 44b1d53 | 2014-04-01 17:08:41 +0200 | [diff] [blame] | 2807 | if (!d_is_dir(victim)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2808 | return -ENOTDIR; |
| 2809 | if (IS_ROOT(victim)) |
| 2810 | return -EBUSY; |
Miklos Szeredi | 44b1d53 | 2014-04-01 17:08:41 +0200 | [diff] [blame] | 2811 | } else if (d_is_dir(victim)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2812 | return -EISDIR; |
| 2813 | if (IS_DEADDIR(dir)) |
| 2814 | return -ENOENT; |
| 2815 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) |
| 2816 | return -EBUSY; |
| 2817 | return 0; |
| 2818 | } |
| 2819 | |
| 2820 | /* Check whether we can create an object with dentry child in directory |
| 2821 | * dir. |
| 2822 | * 1. We can't do it if child already exists (open has special treatment for |
| 2823 | * this case, but since we are inlined it's OK) |
| 2824 | * 2. We can't do it if dir is read-only (done in permission()) |
Eric W. Biederman | 036d523 | 2016-07-01 12:52:06 -0500 | [diff] [blame] | 2825 | * 3. We can't do it if the fs can't represent the fsuid or fsgid. |
| 2826 | * 4. We should have write and exec permissions on dir |
| 2827 | * 5. We can't do it if dir is immutable (done in permission()) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2828 | */ |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 2829 | static inline int may_create(struct inode *dir, struct dentry *child) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2830 | { |
Eric W. Biederman | 036d523 | 2016-07-01 12:52:06 -0500 | [diff] [blame] | 2831 | struct user_namespace *s_user_ns; |
Jeff Layton | 14e972b | 2013-05-08 10:25:58 -0400 | [diff] [blame] | 2832 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2833 | if (child->d_inode) |
| 2834 | return -EEXIST; |
| 2835 | if (IS_DEADDIR(dir)) |
| 2836 | return -ENOENT; |
Eric W. Biederman | 036d523 | 2016-07-01 12:52:06 -0500 | [diff] [blame] | 2837 | s_user_ns = dir->i_sb->s_user_ns; |
| 2838 | if (!kuid_has_mapping(s_user_ns, current_fsuid()) || |
| 2839 | !kgid_has_mapping(s_user_ns, current_fsgid())) |
| 2840 | return -EOVERFLOW; |
Al Viro | f419a2e | 2008-07-22 00:07:17 -0400 | [diff] [blame] | 2841 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2842 | } |
| 2843 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2844 | /* |
| 2845 | * p1 and p2 should be directories on the same fs. |
| 2846 | */ |
| 2847 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) |
| 2848 | { |
| 2849 | struct dentry *p; |
| 2850 | |
| 2851 | if (p1 == p2) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2852 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2853 | return NULL; |
| 2854 | } |
| 2855 | |
Al Viro | fc64005 | 2016-04-10 01:33:30 -0400 | [diff] [blame] | 2856 | mutex_lock(&p1->d_sb->s_vfs_rename_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2857 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2858 | p = d_ancestor(p2, p1); |
| 2859 | if (p) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2860 | inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); |
| 2861 | inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2862 | return p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2863 | } |
| 2864 | |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2865 | p = d_ancestor(p1, p2); |
| 2866 | if (p) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2867 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
| 2868 | inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); |
OGAWA Hirofumi | e2761a1 | 2008-10-16 07:50:28 +0900 | [diff] [blame] | 2869 | return p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2870 | } |
| 2871 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2872 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
| 2873 | inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2874 | return NULL; |
| 2875 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2876 | EXPORT_SYMBOL(lock_rename); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2877 | |
| 2878 | void unlock_rename(struct dentry *p1, struct dentry *p2) |
| 2879 | { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2880 | inode_unlock(p1->d_inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2881 | if (p1 != p2) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2882 | inode_unlock(p2->d_inode); |
Al Viro | fc64005 | 2016-04-10 01:33:30 -0400 | [diff] [blame] | 2883 | mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2884 | } |
| 2885 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2886 | EXPORT_SYMBOL(unlock_rename); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2887 | |
Al Viro | 4acdaf2 | 2011-07-26 01:42:34 -0400 | [diff] [blame] | 2888 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
Al Viro | 312b63f | 2012-06-10 18:09:36 -0400 | [diff] [blame] | 2889 | bool want_excl) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2890 | { |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 2891 | int error = may_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2892 | if (error) |
| 2893 | return error; |
| 2894 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 2895 | if (!dir->i_op->create) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2896 | return -EACCES; /* shouldn't it be ENOSYS? */ |
| 2897 | mode &= S_IALLUGO; |
| 2898 | mode |= S_IFREG; |
| 2899 | error = security_inode_create(dir, dentry, mode); |
| 2900 | if (error) |
| 2901 | return error; |
Al Viro | 312b63f | 2012-06-10 18:09:36 -0400 | [diff] [blame] | 2902 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
Stephen Smalley | a74574a | 2005-09-09 13:01:44 -0700 | [diff] [blame] | 2903 | if (!error) |
Amy Griffis | f38aa94 | 2005-11-03 15:57:06 +0000 | [diff] [blame] | 2904 | fsnotify_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2905 | return error; |
| 2906 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 2907 | EXPORT_SYMBOL(vfs_create); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2908 | |
Al Viro | 8e6c848 | 2017-12-01 17:12:45 -0500 | [diff] [blame] | 2909 | int vfs_mkobj(struct dentry *dentry, umode_t mode, |
| 2910 | int (*f)(struct dentry *, umode_t, void *), |
| 2911 | void *arg) |
| 2912 | { |
| 2913 | struct inode *dir = dentry->d_parent->d_inode; |
| 2914 | int error = may_create(dir, dentry); |
| 2915 | if (error) |
| 2916 | return error; |
| 2917 | |
| 2918 | mode &= S_IALLUGO; |
| 2919 | mode |= S_IFREG; |
| 2920 | error = security_inode_create(dir, dentry, mode); |
| 2921 | if (error) |
| 2922 | return error; |
| 2923 | error = f(dentry, mode, arg); |
| 2924 | if (!error) |
| 2925 | fsnotify_create(dir, dentry); |
| 2926 | return error; |
| 2927 | } |
| 2928 | EXPORT_SYMBOL(vfs_mkobj); |
| 2929 | |
Eric W. Biederman | a2982cc | 2016-06-09 15:34:02 -0500 | [diff] [blame] | 2930 | bool may_open_dev(const struct path *path) |
| 2931 | { |
| 2932 | return !(path->mnt->mnt_flags & MNT_NODEV) && |
| 2933 | !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); |
| 2934 | } |
| 2935 | |
Al Viro | f0bb5aa | 2016-11-20 20:27:12 -0500 | [diff] [blame] | 2936 | static int may_open(const struct path *path, int acc_mode, int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2937 | { |
Christoph Hellwig | 3fb6419 | 2008-10-24 09:58:10 +0200 | [diff] [blame] | 2938 | struct dentry *dentry = path->dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2939 | struct inode *inode = dentry->d_inode; |
| 2940 | int error; |
| 2941 | |
| 2942 | if (!inode) |
| 2943 | return -ENOENT; |
| 2944 | |
Christoph Hellwig | c8fe8f3 | 2009-01-05 19:27:23 +0100 | [diff] [blame] | 2945 | switch (inode->i_mode & S_IFMT) { |
| 2946 | case S_IFLNK: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2947 | return -ELOOP; |
Christoph Hellwig | c8fe8f3 | 2009-01-05 19:27:23 +0100 | [diff] [blame] | 2948 | case S_IFDIR: |
| 2949 | if (acc_mode & MAY_WRITE) |
| 2950 | return -EISDIR; |
| 2951 | break; |
| 2952 | case S_IFBLK: |
| 2953 | case S_IFCHR: |
Eric W. Biederman | a2982cc | 2016-06-09 15:34:02 -0500 | [diff] [blame] | 2954 | if (!may_open_dev(path)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2955 | return -EACCES; |
Christoph Hellwig | c8fe8f3 | 2009-01-05 19:27:23 +0100 | [diff] [blame] | 2956 | /*FALLTHRU*/ |
| 2957 | case S_IFIFO: |
| 2958 | case S_IFSOCK: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2959 | flag &= ~O_TRUNC; |
Christoph Hellwig | c8fe8f3 | 2009-01-05 19:27:23 +0100 | [diff] [blame] | 2960 | break; |
Dave Hansen | 4a3fd21 | 2008-02-15 14:37:48 -0800 | [diff] [blame] | 2961 | } |
Dave Hansen | b41572e | 2007-10-16 23:31:14 -0700 | [diff] [blame] | 2962 | |
Al Viro | 62fb4a1 | 2015-12-26 22:33:24 -0500 | [diff] [blame] | 2963 | error = inode_permission(inode, MAY_OPEN | acc_mode); |
Dave Hansen | b41572e | 2007-10-16 23:31:14 -0700 | [diff] [blame] | 2964 | if (error) |
| 2965 | return error; |
Mimi Zohar | 6146f0d | 2009-02-04 09:06:57 -0500 | [diff] [blame] | 2966 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2967 | /* |
| 2968 | * An append-only file must be opened in append mode for writing. |
| 2969 | */ |
| 2970 | if (IS_APPEND(inode)) { |
Al Viro | 8737c93 | 2009-12-24 06:47:55 -0500 | [diff] [blame] | 2971 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2972 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2973 | if (flag & O_TRUNC) |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2974 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2975 | } |
| 2976 | |
| 2977 | /* O_NOATIME can only be set by the owner or superuser */ |
Serge E. Hallyn | 2e14967 | 2011-03-23 16:43:26 -0700 | [diff] [blame] | 2978 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2979 | return -EPERM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2980 | |
J. Bruce Fields | f3c7691e | 2011-09-21 10:58:13 -0400 | [diff] [blame] | 2981 | return 0; |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2982 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2983 | |
Jeff Layton | e1181ee | 2010-12-07 16:19:50 -0500 | [diff] [blame] | 2984 | static int handle_truncate(struct file *filp) |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2985 | { |
Al Viro | f0bb5aa | 2016-11-20 20:27:12 -0500 | [diff] [blame] | 2986 | const struct path *path = &filp->f_path; |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2987 | struct inode *inode = path->dentry->d_inode; |
| 2988 | int error = get_write_access(inode); |
| 2989 | if (error) |
| 2990 | return error; |
| 2991 | /* |
| 2992 | * Refuse to truncate files with mandatory locks held on them. |
| 2993 | */ |
Jeff Layton | d7a0698 | 2014-03-10 09:54:15 -0400 | [diff] [blame] | 2994 | error = locks_verify_locked(filp); |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2995 | if (!error) |
Tetsuo Handa | ea0d3ab | 2010-06-02 13:24:43 +0900 | [diff] [blame] | 2996 | error = security_path_truncate(path); |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 2997 | if (!error) { |
| 2998 | error = do_truncate(path->dentry, 0, |
| 2999 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, |
Jeff Layton | e1181ee | 2010-12-07 16:19:50 -0500 | [diff] [blame] | 3000 | filp); |
Al Viro | 7715b52 | 2009-12-16 03:54:00 -0500 | [diff] [blame] | 3001 | } |
| 3002 | put_write_access(inode); |
Mimi Zohar | acd0c93 | 2009-09-04 13:08:46 -0400 | [diff] [blame] | 3003 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3004 | } |
| 3005 | |
Dave Hansen | d57999e | 2008-02-15 14:37:27 -0800 | [diff] [blame] | 3006 | static inline int open_to_namei_flags(int flag) |
| 3007 | { |
Al Viro | 8a5e929 | 2011-06-25 19:15:54 -0400 | [diff] [blame] | 3008 | if ((flag & O_ACCMODE) == 3) |
| 3009 | flag--; |
Dave Hansen | d57999e | 2008-02-15 14:37:27 -0800 | [diff] [blame] | 3010 | return flag; |
| 3011 | } |
| 3012 | |
Al Viro | d360775 | 2016-03-25 15:21:09 -0400 | [diff] [blame] | 3013 | static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3014 | { |
Seth Forshee | 1328c72 | 2017-01-26 14:33:46 -0600 | [diff] [blame] | 3015 | struct user_namespace *s_user_ns; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3016 | int error = security_path_mknod(dir, dentry, mode, 0); |
| 3017 | if (error) |
| 3018 | return error; |
| 3019 | |
Seth Forshee | 1328c72 | 2017-01-26 14:33:46 -0600 | [diff] [blame] | 3020 | s_user_ns = dir->dentry->d_sb->s_user_ns; |
| 3021 | if (!kuid_has_mapping(s_user_ns, current_fsuid()) || |
| 3022 | !kgid_has_mapping(s_user_ns, current_fsgid())) |
| 3023 | return -EOVERFLOW; |
| 3024 | |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3025 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); |
| 3026 | if (error) |
| 3027 | return error; |
| 3028 | |
| 3029 | return security_inode_create(dir->dentry->d_inode, dentry, mode); |
| 3030 | } |
| 3031 | |
David Howells | 1acf0af | 2012-06-14 16:13:46 +0100 | [diff] [blame] | 3032 | /* |
| 3033 | * Attempt to atomically look up, create and open a file from a negative |
| 3034 | * dentry. |
| 3035 | * |
| 3036 | * Returns 0 if successful. The file will have been created and attached to |
| 3037 | * @file by the filesystem calling finish_open(). |
| 3038 | * |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3039 | * If the file was looked up only or didn't need creating, FMODE_OPENED won't |
| 3040 | * be set. The caller will need to perform the open themselves. @path will |
| 3041 | * have been updated to point to the new dentry. This may be negative. |
David Howells | 1acf0af | 2012-06-14 16:13:46 +0100 | [diff] [blame] | 3042 | * |
| 3043 | * Returns an error code otherwise. |
| 3044 | */ |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3045 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
| 3046 | struct path *path, struct file *file, |
| 3047 | const struct open_flags *op, |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3048 | int open_flag, umode_t mode) |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3049 | { |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3050 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3051 | struct inode *dir = nd->path.dentry->d_inode; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3052 | int error; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3053 | |
Al Viro | 384f26e | 2016-04-28 02:03:55 -0400 | [diff] [blame] | 3054 | if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3055 | open_flag &= ~O_TRUNC; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3056 | |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3057 | if (nd->flags & LOOKUP_DIRECTORY) |
| 3058 | open_flag |= O_DIRECTORY; |
| 3059 | |
Al Viro | 30d90494 | 2012-06-22 12:40:19 +0400 | [diff] [blame] | 3060 | file->f_path.dentry = DENTRY_NOT_SET; |
| 3061 | file->f_path.mnt = nd->path.mnt; |
Al Viro | 0fb1ea0 | 2016-04-27 14:13:10 -0400 | [diff] [blame] | 3062 | error = dir->i_op->atomic_open(dir, dentry, file, |
Al Viro | 44907d7 | 2018-06-08 13:32:02 -0400 | [diff] [blame] | 3063 | open_to_namei_flags(open_flag), mode); |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3064 | d_lookup_done(dentry); |
Al Viro | 384f26e | 2016-04-28 02:03:55 -0400 | [diff] [blame] | 3065 | if (!error) { |
Al Viro | 64e1ac4 | 2018-07-09 19:17:52 -0400 | [diff] [blame] | 3066 | if (file->f_mode & FMODE_OPENED) { |
| 3067 | /* |
| 3068 | * We didn't have the inode before the open, so check open |
| 3069 | * permission here. |
| 3070 | */ |
| 3071 | int acc_mode = op->acc_mode; |
| 3072 | if (file->f_mode & FMODE_CREATED) { |
| 3073 | WARN_ON(!(open_flag & O_CREAT)); |
| 3074 | fsnotify_create(dir, dentry); |
| 3075 | acc_mode = 0; |
| 3076 | } |
| 3077 | error = may_open(&file->f_path, acc_mode, open_flag); |
| 3078 | if (WARN_ON(error > 0)) |
| 3079 | error = -EINVAL; |
| 3080 | } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3081 | error = -EIO; |
Al Viro | 03da633 | 2013-09-16 19:22:33 -0400 | [diff] [blame] | 3082 | } else { |
Al Viro | 384f26e | 2016-04-28 02:03:55 -0400 | [diff] [blame] | 3083 | if (file->f_path.dentry) { |
| 3084 | dput(dentry); |
| 3085 | dentry = file->f_path.dentry; |
Al Viro | 03da633 | 2013-09-16 19:22:33 -0400 | [diff] [blame] | 3086 | } |
Al Viro | 73a09dd | 2018-06-08 13:22:02 -0400 | [diff] [blame] | 3087 | if (file->f_mode & FMODE_CREATED) |
Al Viro | 384f26e | 2016-04-28 02:03:55 -0400 | [diff] [blame] | 3088 | fsnotify_create(dir, dentry); |
Al Viro | a01e718 | 2016-06-07 21:53:51 -0400 | [diff] [blame] | 3089 | if (unlikely(d_is_negative(dentry))) { |
| 3090 | error = -ENOENT; |
| 3091 | } else { |
| 3092 | path->dentry = dentry; |
| 3093 | path->mnt = nd->path.mnt; |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3094 | return 0; |
Al Viro | a01e718 | 2016-06-07 21:53:51 -0400 | [diff] [blame] | 3095 | } |
Sage Weil | 62b2ce9 | 2012-08-15 13:30:12 -0700 | [diff] [blame] | 3096 | } |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3097 | } |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3098 | dput(dentry); |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3099 | return error; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3100 | } |
| 3101 | |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 3102 | /* |
David Howells | 1acf0af | 2012-06-14 16:13:46 +0100 | [diff] [blame] | 3103 | * Look up and maybe create and open the last component. |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3104 | * |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3105 | * Must be called with parent locked (exclusive in O_CREAT case). |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3106 | * |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3107 | * Returns 0 on success, that is, if |
| 3108 | * the file was successfully atomically created (if necessary) and opened, or |
| 3109 | * the file was not completely opened at this time, though lookups and |
| 3110 | * creations were performed. |
| 3111 | * These case are distinguished by presence of FMODE_OPENED on file->f_mode. |
| 3112 | * In the latter case dentry returned in @path might be negative if O_CREAT |
| 3113 | * hadn't been specified. |
David Howells | 1acf0af | 2012-06-14 16:13:46 +0100 | [diff] [blame] | 3114 | * |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3115 | * An error code is returned on failure. |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3116 | */ |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3117 | static int lookup_open(struct nameidata *nd, struct path *path, |
| 3118 | struct file *file, |
| 3119 | const struct open_flags *op, |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3120 | bool got_write) |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3121 | { |
| 3122 | struct dentry *dir = nd->path.dentry; |
Miklos Szeredi | 54ef487 | 2012-06-05 15:10:16 +0200 | [diff] [blame] | 3123 | struct inode *dir_inode = dir->d_inode; |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3124 | int open_flag = op->open_flag; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3125 | struct dentry *dentry; |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3126 | int error, create_error = 0; |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3127 | umode_t mode = op->mode; |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3128 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3129 | |
Al Viro | ce8644f | 2016-04-26 14:17:56 -0400 | [diff] [blame] | 3130 | if (unlikely(IS_DEADDIR(dir_inode))) |
| 3131 | return -ENOENT; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3132 | |
Al Viro | 73a09dd | 2018-06-08 13:22:02 -0400 | [diff] [blame] | 3133 | file->f_mode &= ~FMODE_CREATED; |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3134 | dentry = d_lookup(dir, &nd->last); |
| 3135 | for (;;) { |
| 3136 | if (!dentry) { |
| 3137 | dentry = d_alloc_parallel(dir, &nd->last, &wq); |
| 3138 | if (IS_ERR(dentry)) |
| 3139 | return PTR_ERR(dentry); |
| 3140 | } |
| 3141 | if (d_in_lookup(dentry)) |
| 3142 | break; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3143 | |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3144 | error = d_revalidate(dentry, nd->flags); |
| 3145 | if (likely(error > 0)) |
| 3146 | break; |
| 3147 | if (error) |
| 3148 | goto out_dput; |
| 3149 | d_invalidate(dentry); |
| 3150 | dput(dentry); |
| 3151 | dentry = NULL; |
| 3152 | } |
| 3153 | if (dentry->d_inode) { |
Al Viro | 6c51e51 | 2016-03-05 20:09:32 -0500 | [diff] [blame] | 3154 | /* Cached positive dentry: will open in f_op->open */ |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3155 | goto out_no_open; |
Al Viro | 6c51e51 | 2016-03-05 20:09:32 -0500 | [diff] [blame] | 3156 | } |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3157 | |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3158 | /* |
| 3159 | * Checking write permission is tricky, bacuse we don't know if we are |
| 3160 | * going to actually need it: O_CREAT opens should work as long as the |
| 3161 | * file exists. But checking existence breaks atomicity. The trick is |
| 3162 | * to check access and if not granted clear O_CREAT from the flags. |
| 3163 | * |
| 3164 | * Another problem is returing the "right" error value (e.g. for an |
| 3165 | * O_EXCL open we want to return EEXIST not EROFS). |
| 3166 | */ |
| 3167 | if (open_flag & O_CREAT) { |
| 3168 | if (!IS_POSIXACL(dir->d_inode)) |
| 3169 | mode &= ~current_umask(); |
| 3170 | if (unlikely(!got_write)) { |
| 3171 | create_error = -EROFS; |
| 3172 | open_flag &= ~O_CREAT; |
| 3173 | if (open_flag & (O_EXCL | O_TRUNC)) |
| 3174 | goto no_open; |
| 3175 | /* No side effects, safe to clear O_CREAT */ |
| 3176 | } else { |
| 3177 | create_error = may_o_create(&nd->path, dentry, mode); |
| 3178 | if (create_error) { |
| 3179 | open_flag &= ~O_CREAT; |
| 3180 | if (open_flag & O_EXCL) |
| 3181 | goto no_open; |
| 3182 | } |
| 3183 | } |
| 3184 | } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && |
| 3185 | unlikely(!got_write)) { |
| 3186 | /* |
| 3187 | * No O_CREATE -> atomicity not a requirement -> fall |
| 3188 | * back to lookup + open |
| 3189 | */ |
| 3190 | goto no_open; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3191 | } |
| 3192 | |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3193 | if (dir_inode->i_op->atomic_open) { |
| 3194 | error = atomic_open(nd, dentry, path, file, op, open_flag, |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3195 | mode); |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3196 | if (unlikely(error == -ENOENT) && create_error) |
| 3197 | error = create_error; |
| 3198 | return error; |
| 3199 | } |
Miklos Szeredi | 54ef487 | 2012-06-05 15:10:16 +0200 | [diff] [blame] | 3200 | |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3201 | no_open: |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3202 | if (d_in_lookup(dentry)) { |
Al Viro | 12fa5e2 | 2016-04-28 11:19:43 -0400 | [diff] [blame] | 3203 | struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, |
| 3204 | nd->flags); |
Al Viro | 6fbd071 | 2016-04-28 11:50:59 -0400 | [diff] [blame] | 3205 | d_lookup_done(dentry); |
Al Viro | 12fa5e2 | 2016-04-28 11:19:43 -0400 | [diff] [blame] | 3206 | if (unlikely(res)) { |
| 3207 | if (IS_ERR(res)) { |
| 3208 | error = PTR_ERR(res); |
| 3209 | goto out_dput; |
| 3210 | } |
| 3211 | dput(dentry); |
| 3212 | dentry = res; |
| 3213 | } |
Miklos Szeredi | 54ef487 | 2012-06-05 15:10:16 +0200 | [diff] [blame] | 3214 | } |
| 3215 | |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3216 | /* Negative dentry, just create the file */ |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3217 | if (!dentry->d_inode && (open_flag & O_CREAT)) { |
Al Viro | 73a09dd | 2018-06-08 13:22:02 -0400 | [diff] [blame] | 3218 | file->f_mode |= FMODE_CREATED; |
Al Viro | ce8644f | 2016-04-26 14:17:56 -0400 | [diff] [blame] | 3219 | audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); |
Al Viro | ce8644f | 2016-04-26 14:17:56 -0400 | [diff] [blame] | 3220 | if (!dir_inode->i_op->create) { |
| 3221 | error = -EACCES; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3222 | goto out_dput; |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3223 | } |
Al Viro | ce8644f | 2016-04-26 14:17:56 -0400 | [diff] [blame] | 3224 | error = dir_inode->i_op->create(dir_inode, dentry, mode, |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3225 | open_flag & O_EXCL); |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3226 | if (error) |
| 3227 | goto out_dput; |
Al Viro | ce8644f | 2016-04-26 14:17:56 -0400 | [diff] [blame] | 3228 | fsnotify_create(dir_inode, dentry); |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3229 | } |
Al Viro | 1643b43 | 2016-04-27 19:14:10 -0400 | [diff] [blame] | 3230 | if (unlikely(create_error) && !dentry->d_inode) { |
| 3231 | error = create_error; |
| 3232 | goto out_dput; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3233 | } |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3234 | out_no_open: |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3235 | path->dentry = dentry; |
| 3236 | path->mnt = nd->path.mnt; |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3237 | return 0; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3238 | |
| 3239 | out_dput: |
| 3240 | dput(dentry); |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3241 | return error; |
Miklos Szeredi | d58ffd3 | 2012-06-05 15:10:15 +0200 | [diff] [blame] | 3242 | } |
| 3243 | |
| 3244 | /* |
Al Viro | fe2d35f | 2011-03-05 22:58:25 -0500 | [diff] [blame] | 3245 | * Handle the last step of open() |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 3246 | */ |
Al Viro | 896475d | 2015-04-22 18:02:17 -0400 | [diff] [blame] | 3247 | static int do_last(struct nameidata *nd, |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3248 | struct file *file, const struct open_flags *op) |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3249 | { |
Al Viro | a1e2803 | 2009-12-24 02:12:06 -0500 | [diff] [blame] | 3250 | struct dentry *dir = nd->path.dentry; |
Al Viro | ca344a89 | 2011-03-09 00:36:45 -0500 | [diff] [blame] | 3251 | int open_flag = op->open_flag; |
Miklos Szeredi | 77d660a | 2012-06-05 15:10:30 +0200 | [diff] [blame] | 3252 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3253 | bool got_write = false; |
Al Viro | bcda765 | 2011-03-13 16:42:14 -0400 | [diff] [blame] | 3254 | int acc_mode = op->acc_mode; |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 3255 | unsigned seq; |
Miklos Szeredi | a1eb331 | 2012-05-21 17:30:07 +0200 | [diff] [blame] | 3256 | struct inode *inode; |
Al Viro | 896475d | 2015-04-22 18:02:17 -0400 | [diff] [blame] | 3257 | struct path path; |
Al Viro | 16c2cd7 | 2011-02-22 15:50:10 -0500 | [diff] [blame] | 3258 | int error; |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3259 | |
Al Viro | c3e380b | 2011-02-23 13:39:45 -0500 | [diff] [blame] | 3260 | nd->flags &= ~LOOKUP_PARENT; |
| 3261 | nd->flags |= op->intent; |
| 3262 | |
Al Viro | bc77daa | 2013-06-06 09:12:33 -0400 | [diff] [blame] | 3263 | if (nd->last_type != LAST_NORM) { |
Al Viro | fe2d35f | 2011-03-05 22:58:25 -0500 | [diff] [blame] | 3264 | error = handle_dots(nd, nd->last_type); |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 3265 | if (unlikely(error)) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3266 | return error; |
Miklos Szeredi | e83db16 | 2012-06-05 15:10:29 +0200 | [diff] [blame] | 3267 | goto finish_open; |
Al Viro | 1f36f77 | 2009-12-26 10:56:19 -0500 | [diff] [blame] | 3268 | } |
Al Viro | 67ee3ad | 2009-12-26 07:01:01 -0500 | [diff] [blame] | 3269 | |
Al Viro | ca344a89 | 2011-03-09 00:36:45 -0500 | [diff] [blame] | 3270 | if (!(open_flag & O_CREAT)) { |
Al Viro | fe2d35f | 2011-03-05 22:58:25 -0500 | [diff] [blame] | 3271 | if (nd->last.name[nd->last.len]) |
| 3272 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
| 3273 | /* we _can_ be in RCU mode here */ |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 3274 | error = lookup_fast(nd, &path, &inode, &seq); |
Al Viro | e9742b5 | 2016-03-05 22:04:59 -0500 | [diff] [blame] | 3275 | if (likely(error > 0)) |
Miklos Szeredi | 7157486 | 2012-06-05 15:10:14 +0200 | [diff] [blame] | 3276 | goto finish_lookup; |
Miklos Szeredi | a1eb331 | 2012-05-21 17:30:07 +0200 | [diff] [blame] | 3277 | |
Miklos Szeredi | 7157486 | 2012-06-05 15:10:14 +0200 | [diff] [blame] | 3278 | if (error < 0) |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 3279 | return error; |
Miklos Szeredi | 37d7fff | 2012-06-05 15:10:12 +0200 | [diff] [blame] | 3280 | |
Miklos Szeredi | 7157486 | 2012-06-05 15:10:14 +0200 | [diff] [blame] | 3281 | BUG_ON(nd->inode != dir->d_inode); |
Al Viro | 6583fe2 | 2016-03-05 18:14:03 -0500 | [diff] [blame] | 3282 | BUG_ON(nd->flags & LOOKUP_RCU); |
Miklos Szeredi | b6183df | 2012-06-05 15:10:13 +0200 | [diff] [blame] | 3283 | } else { |
| 3284 | /* create side of things */ |
| 3285 | /* |
| 3286 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED |
| 3287 | * has been cleared when we got to the last component we are |
| 3288 | * about to look up |
| 3289 | */ |
| 3290 | error = complete_walk(nd); |
Al Viro | e8bb73d | 2015-05-08 16:28:42 -0400 | [diff] [blame] | 3291 | if (error) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3292 | return error; |
Miklos Szeredi | b6183df | 2012-06-05 15:10:13 +0200 | [diff] [blame] | 3293 | |
Al Viro | c9b07ea | 2019-07-14 13:22:27 -0400 | [diff] [blame] | 3294 | audit_inode(nd->name, dir, AUDIT_INODE_PARENT); |
Miklos Szeredi | b6183df | 2012-06-05 15:10:13 +0200 | [diff] [blame] | 3295 | /* trailing slashes? */ |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 3296 | if (unlikely(nd->last.name[nd->last.len])) |
| 3297 | return -EISDIR; |
Al Viro | fe2d35f | 2011-03-05 22:58:25 -0500 | [diff] [blame] | 3298 | } |
| 3299 | |
Al Viro | 9cf843e | 2016-04-28 19:35:16 -0400 | [diff] [blame] | 3300 | if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3301 | error = mnt_want_write(nd->path.mnt); |
| 3302 | if (!error) |
| 3303 | got_write = true; |
| 3304 | /* |
| 3305 | * do _not_ fail yet - we might not need that or fail with |
| 3306 | * a different error; let lookup_open() decide; we'll be |
| 3307 | * dropping this one anyway. |
| 3308 | */ |
| 3309 | } |
Al Viro | 9cf843e | 2016-04-28 19:35:16 -0400 | [diff] [blame] | 3310 | if (open_flag & O_CREAT) |
| 3311 | inode_lock(dir->d_inode); |
| 3312 | else |
| 3313 | inode_lock_shared(dir->d_inode); |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3314 | error = lookup_open(nd, &path, file, op, got_write); |
Al Viro | 9cf843e | 2016-04-28 19:35:16 -0400 | [diff] [blame] | 3315 | if (open_flag & O_CREAT) |
| 3316 | inode_unlock(dir->d_inode); |
| 3317 | else |
| 3318 | inode_unlock_shared(dir->d_inode); |
Al Viro | a1e2803 | 2009-12-24 02:12:06 -0500 | [diff] [blame] | 3319 | |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3320 | if (error) |
| 3321 | goto out; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3322 | |
Al Viro | 00a07c1 | 2018-07-09 19:30:20 -0400 | [diff] [blame] | 3323 | if (file->f_mode & FMODE_OPENED) { |
Al Viro | 73a09dd | 2018-06-08 13:22:02 -0400 | [diff] [blame] | 3324 | if ((file->f_mode & FMODE_CREATED) || |
Al Viro | 496ad9a | 2013-01-23 17:07:38 -0500 | [diff] [blame] | 3325 | !S_ISREG(file_inode(file)->i_mode)) |
Miklos Szeredi | 77d660a | 2012-06-05 15:10:30 +0200 | [diff] [blame] | 3326 | will_truncate = false; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3327 | |
Al Viro | 76ae2a5 | 2015-05-12 18:44:32 -0400 | [diff] [blame] | 3328 | audit_inode(nd->name, file->f_path.dentry, 0); |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3329 | goto opened; |
| 3330 | } |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3331 | |
Al Viro | 73a09dd | 2018-06-08 13:22:02 -0400 | [diff] [blame] | 3332 | if (file->f_mode & FMODE_CREATED) { |
Al Viro | 9b44f1b | 2011-03-09 00:17:27 -0500 | [diff] [blame] | 3333 | /* Don't check for write permission, don't truncate */ |
Al Viro | ca344a89 | 2011-03-09 00:36:45 -0500 | [diff] [blame] | 3334 | open_flag &= ~O_TRUNC; |
Miklos Szeredi | 77d660a | 2012-06-05 15:10:30 +0200 | [diff] [blame] | 3335 | will_truncate = false; |
Al Viro | 62fb4a1 | 2015-12-26 22:33:24 -0500 | [diff] [blame] | 3336 | acc_mode = 0; |
Al Viro | 896475d | 2015-04-22 18:02:17 -0400 | [diff] [blame] | 3337 | path_to_nameidata(&path, nd); |
Miklos Szeredi | e83db16 | 2012-06-05 15:10:29 +0200 | [diff] [blame] | 3338 | goto finish_open_created; |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3339 | } |
| 3340 | |
| 3341 | /* |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3342 | * If atomic_open() acquired write access it is dropped now due to |
| 3343 | * possible mount and symlink following (this might be optimized away if |
| 3344 | * necessary...) |
| 3345 | */ |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3346 | if (got_write) { |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3347 | mnt_drop_write(nd->path.mnt); |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3348 | got_write = false; |
Miklos Szeredi | d18e900 | 2012-06-05 15:10:17 +0200 | [diff] [blame] | 3349 | } |
| 3350 | |
Al Viro | e6ec03a | 2016-06-05 00:23:09 -0400 | [diff] [blame] | 3351 | error = follow_managed(&path, nd); |
| 3352 | if (unlikely(error < 0)) |
| 3353 | return error; |
| 3354 | |
Al Viro | 6583fe2 | 2016-03-05 18:14:03 -0500 | [diff] [blame] | 3355 | if (unlikely(d_is_negative(path.dentry))) { |
| 3356 | path_to_nameidata(&path, nd); |
| 3357 | return -ENOENT; |
| 3358 | } |
| 3359 | |
| 3360 | /* |
| 3361 | * create/update audit record if it already exists. |
| 3362 | */ |
| 3363 | audit_inode(nd->name, path.dentry, 0); |
| 3364 | |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 3365 | if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { |
| 3366 | path_to_nameidata(&path, nd); |
| 3367 | return -EEXIST; |
| 3368 | } |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3369 | |
Al Viro | 254cf58 | 2015-05-05 09:40:46 -0400 | [diff] [blame] | 3370 | seq = 0; /* out of RCU mode, so the value doesn't matter */ |
Al Viro | d456564 | 2016-02-27 19:23:16 -0500 | [diff] [blame] | 3371 | inode = d_backing_inode(path.dentry); |
Al Viro | 766c4cb | 2015-05-07 19:24:57 -0400 | [diff] [blame] | 3372 | finish_lookup: |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 3373 | error = step_into(nd, &path, 0, inode, seq); |
Al Viro | deb106c | 2015-05-08 18:05:21 -0400 | [diff] [blame] | 3374 | if (unlikely(error)) |
Al Viro | d63ff28 | 2015-05-04 18:13:23 -0400 | [diff] [blame] | 3375 | return error; |
Al Viro | bc77daa | 2013-06-06 09:12:33 -0400 | [diff] [blame] | 3376 | finish_open: |
Al Viro | 8f64fb1 | 2016-11-14 01:50:26 -0500 | [diff] [blame] | 3377 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
Al Viro | a3fbbde | 2011-11-07 21:21:26 +0000 | [diff] [blame] | 3378 | error = complete_walk(nd); |
Al Viro | fac7d19 | 2016-06-04 11:41:49 -0400 | [diff] [blame] | 3379 | if (error) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3380 | return error; |
Al Viro | 76ae2a5 | 2015-05-12 18:44:32 -0400 | [diff] [blame] | 3381 | audit_inode(nd->name, nd->path.dentry, 0); |
Salvatore Mesoraca | 30aba66 | 2018-08-23 17:00:35 -0700 | [diff] [blame] | 3382 | if (open_flag & O_CREAT) { |
| 3383 | error = -EISDIR; |
| 3384 | if (d_is_dir(nd->path.dentry)) |
| 3385 | goto out; |
| 3386 | error = may_create_in_sticky(dir, |
| 3387 | d_backing_inode(nd->path.dentry)); |
| 3388 | if (unlikely(error)) |
| 3389 | goto out; |
| 3390 | } |
Miklos Szeredi | af2f554 | 2012-05-21 17:30:11 +0200 | [diff] [blame] | 3391 | error = -ENOTDIR; |
Miklos Szeredi | 44b1d53 | 2014-04-01 17:08:41 +0200 | [diff] [blame] | 3392 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3393 | goto out; |
David Howells | 4bbcbd3b | 2015-03-17 22:16:40 +0000 | [diff] [blame] | 3394 | if (!d_is_reg(nd->path.dentry)) |
Miklos Szeredi | 77d660a | 2012-06-05 15:10:30 +0200 | [diff] [blame] | 3395 | will_truncate = false; |
Al Viro | 6c0d46c | 2011-03-09 00:59:59 -0500 | [diff] [blame] | 3396 | |
Al Viro | 0f9d1a1 | 2011-03-09 00:13:14 -0500 | [diff] [blame] | 3397 | if (will_truncate) { |
| 3398 | error = mnt_want_write(nd->path.mnt); |
| 3399 | if (error) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3400 | goto out; |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3401 | got_write = true; |
Al Viro | 0f9d1a1 | 2011-03-09 00:13:14 -0500 | [diff] [blame] | 3402 | } |
Miklos Szeredi | e83db16 | 2012-06-05 15:10:29 +0200 | [diff] [blame] | 3403 | finish_open_created: |
Al Viro | 6ac0870 | 2016-04-26 00:02:50 -0400 | [diff] [blame] | 3404 | error = may_open(&nd->path, acc_mode, open_flag); |
| 3405 | if (error) |
| 3406 | goto out; |
Al Viro | aad888f | 2018-06-08 12:58:04 -0400 | [diff] [blame] | 3407 | BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */ |
Al Viro | ae2bb29 | 2018-07-10 13:22:28 -0400 | [diff] [blame] | 3408 | error = vfs_open(&nd->path, file); |
Al Viro | fac7d19 | 2016-06-04 11:41:49 -0400 | [diff] [blame] | 3409 | if (error) |
Miklos Szeredi | 015c3bb | 2012-06-05 15:10:27 +0200 | [diff] [blame] | 3410 | goto out; |
Miklos Szeredi | a8277b9 | 2012-06-05 15:10:32 +0200 | [diff] [blame] | 3411 | opened: |
Al Viro | 6035a27 | 2018-06-08 13:40:10 -0400 | [diff] [blame] | 3412 | error = ima_file_check(file, op->acc_mode); |
Al Viro | fe9ec82 | 2016-04-27 03:14:20 -0400 | [diff] [blame] | 3413 | if (!error && will_truncate) |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3414 | error = handle_truncate(file); |
Al Viro | ca344a89 | 2011-03-09 00:36:45 -0500 | [diff] [blame] | 3415 | out: |
Al Viro | c80567c | 2016-02-27 19:17:33 -0500 | [diff] [blame] | 3416 | if (unlikely(error > 0)) { |
| 3417 | WARN_ON(1); |
| 3418 | error = -EINVAL; |
| 3419 | } |
Al Viro | 64894cf | 2012-07-31 00:53:35 +0400 | [diff] [blame] | 3420 | if (got_write) |
Al Viro | 0f9d1a1 | 2011-03-09 00:13:14 -0500 | [diff] [blame] | 3421 | mnt_drop_write(nd->path.mnt); |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3422 | return error; |
Al Viro | fb1cc55 | 2009-12-24 01:58:28 -0500 | [diff] [blame] | 3423 | } |
| 3424 | |
Amir Goldstein | af7bd4d | 2017-01-17 06:34:52 +0200 | [diff] [blame] | 3425 | struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag) |
| 3426 | { |
Amir Goldstein | af7bd4d | 2017-01-17 06:34:52 +0200 | [diff] [blame] | 3427 | struct dentry *child = NULL; |
| 3428 | struct inode *dir = dentry->d_inode; |
| 3429 | struct inode *inode; |
| 3430 | int error; |
| 3431 | |
| 3432 | /* we want directory to be writable */ |
| 3433 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
| 3434 | if (error) |
| 3435 | goto out_err; |
| 3436 | error = -EOPNOTSUPP; |
| 3437 | if (!dir->i_op->tmpfile) |
| 3438 | goto out_err; |
| 3439 | error = -ENOMEM; |
David Howells | cdf0122 | 2017-07-04 17:25:22 +0100 | [diff] [blame] | 3440 | child = d_alloc(dentry, &slash_name); |
Amir Goldstein | af7bd4d | 2017-01-17 06:34:52 +0200 | [diff] [blame] | 3441 | if (unlikely(!child)) |
| 3442 | goto out_err; |
| 3443 | error = dir->i_op->tmpfile(dir, child, mode); |
| 3444 | if (error) |
| 3445 | goto out_err; |
| 3446 | error = -ENOENT; |
| 3447 | inode = child->d_inode; |
| 3448 | if (unlikely(!inode)) |
| 3449 | goto out_err; |
| 3450 | if (!(open_flag & O_EXCL)) { |
| 3451 | spin_lock(&inode->i_lock); |
| 3452 | inode->i_state |= I_LINKABLE; |
| 3453 | spin_unlock(&inode->i_lock); |
| 3454 | } |
Mimi Zohar | fdb2410 | 2019-01-22 14:06:49 -0600 | [diff] [blame] | 3455 | ima_post_create_tmpfile(inode); |
Amir Goldstein | af7bd4d | 2017-01-17 06:34:52 +0200 | [diff] [blame] | 3456 | return child; |
| 3457 | |
| 3458 | out_err: |
| 3459 | dput(child); |
| 3460 | return ERR_PTR(error); |
| 3461 | } |
| 3462 | EXPORT_SYMBOL(vfs_tmpfile); |
| 3463 | |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3464 | static int do_tmpfile(struct nameidata *nd, unsigned flags, |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3465 | const struct open_flags *op, |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3466 | struct file *file) |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3467 | { |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3468 | struct dentry *child; |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3469 | struct path path; |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3470 | int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3471 | if (unlikely(error)) |
| 3472 | return error; |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3473 | error = mnt_want_write(path.mnt); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3474 | if (unlikely(error)) |
| 3475 | goto out; |
Amir Goldstein | af7bd4d | 2017-01-17 06:34:52 +0200 | [diff] [blame] | 3476 | child = vfs_tmpfile(path.dentry, op->mode, op->open_flag); |
| 3477 | error = PTR_ERR(child); |
Hirofumi Nakagawa | 684e73b | 2017-09-26 03:21:26 +0900 | [diff] [blame] | 3478 | if (IS_ERR(child)) |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3479 | goto out2; |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3480 | dput(path.dentry); |
| 3481 | path.dentry = child; |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3482 | audit_inode(nd->name, child, 0); |
Eric Rannaud | 69a91c2 | 2014-10-30 01:51:01 -0700 | [diff] [blame] | 3483 | /* Don't check for other permissions, the inode was just created */ |
Al Viro | 62fb4a1 | 2015-12-26 22:33:24 -0500 | [diff] [blame] | 3484 | error = may_open(&path, 0, op->open_flag); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3485 | if (error) |
| 3486 | goto out2; |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3487 | file->f_path.mnt = path.mnt; |
Al Viro | be12af3 | 2018-06-08 11:44:56 -0400 | [diff] [blame] | 3488 | error = finish_open(file, child, NULL); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3489 | out2: |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3490 | mnt_drop_write(path.mnt); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3491 | out: |
Al Viro | 625b6d1 | 2015-05-12 16:36:12 -0400 | [diff] [blame] | 3492 | path_put(&path); |
Al Viro | 60545d0 | 2013-06-07 01:20:27 -0400 | [diff] [blame] | 3493 | return error; |
| 3494 | } |
| 3495 | |
Al Viro | 6ac0870 | 2016-04-26 00:02:50 -0400 | [diff] [blame] | 3496 | static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) |
| 3497 | { |
| 3498 | struct path path; |
| 3499 | int error = path_lookupat(nd, flags, &path); |
| 3500 | if (!error) { |
| 3501 | audit_inode(nd->name, path.dentry, 0); |
Al Viro | ae2bb29 | 2018-07-10 13:22:28 -0400 | [diff] [blame] | 3502 | error = vfs_open(&path, file); |
Al Viro | 6ac0870 | 2016-04-26 00:02:50 -0400 | [diff] [blame] | 3503 | path_put(&path); |
| 3504 | } |
| 3505 | return error; |
| 3506 | } |
| 3507 | |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3508 | static struct file *path_openat(struct nameidata *nd, |
| 3509 | const struct open_flags *op, unsigned flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3510 | { |
Al Viro | 30d90494 | 2012-06-22 12:40:19 +0400 | [diff] [blame] | 3511 | struct file *file; |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3512 | int error; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 3513 | |
Al Viro | ea73ea7 | 2018-07-11 15:00:04 -0400 | [diff] [blame] | 3514 | file = alloc_empty_file(op->open_flag, current_cred()); |
Al Viro | 1afc99b | 2013-02-14 20:41:04 -0500 | [diff] [blame] | 3515 | if (IS_ERR(file)) |
| 3516 | return file; |
Nick Piggin | 31e6b01 | 2011-01-07 17:49:52 +1100 | [diff] [blame] | 3517 | |
Al Viro | bb458c6 | 2013-07-13 13:26:37 +0400 | [diff] [blame] | 3518 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
Al Viro | 3ec2eef | 2018-06-08 13:43:47 -0400 | [diff] [blame] | 3519 | error = do_tmpfile(nd, flags, op, file); |
Al Viro | 5f336e7 | 2018-07-09 16:38:06 -0400 | [diff] [blame] | 3520 | } else if (unlikely(file->f_flags & O_PATH)) { |
Al Viro | 6ac0870 | 2016-04-26 00:02:50 -0400 | [diff] [blame] | 3521 | error = do_o_path(nd, flags, file); |
Al Viro | 5f336e7 | 2018-07-09 16:38:06 -0400 | [diff] [blame] | 3522 | } else { |
| 3523 | const char *s = path_init(nd, flags); |
| 3524 | while (!(error = link_path_walk(s, nd)) && |
| 3525 | (error = do_last(nd, file, op)) > 0) { |
| 3526 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
| 3527 | s = trailing_symlink(nd); |
| 3528 | } |
| 3529 | terminate_walk(nd); |
Al Viro | 6ac0870 | 2016-04-26 00:02:50 -0400 | [diff] [blame] | 3530 | } |
Al Viro | 7c1c01e | 2018-06-08 12:56:55 -0400 | [diff] [blame] | 3531 | if (likely(!error)) { |
Al Viro | aad888f | 2018-06-08 12:58:04 -0400 | [diff] [blame] | 3532 | if (likely(file->f_mode & FMODE_OPENED)) |
Al Viro | 7c1c01e | 2018-06-08 12:56:55 -0400 | [diff] [blame] | 3533 | return file; |
| 3534 | WARN_ON(1); |
| 3535 | error = -EINVAL; |
Miklos Szeredi | 015c3bb | 2012-06-05 15:10:27 +0200 | [diff] [blame] | 3536 | } |
Al Viro | 7c1c01e | 2018-06-08 12:56:55 -0400 | [diff] [blame] | 3537 | fput(file); |
| 3538 | if (error == -EOPENSTALE) { |
| 3539 | if (flags & LOOKUP_RCU) |
| 3540 | error = -ECHILD; |
| 3541 | else |
| 3542 | error = -ESTALE; |
Al Viro | 2675a4e | 2012-06-22 12:41:10 +0400 | [diff] [blame] | 3543 | } |
Al Viro | 7c1c01e | 2018-06-08 12:56:55 -0400 | [diff] [blame] | 3544 | return ERR_PTR(error); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3545 | } |
| 3546 | |
Jeff Layton | 669abf4 | 2012-10-10 16:43:10 -0400 | [diff] [blame] | 3547 | struct file *do_filp_open(int dfd, struct filename *pathname, |
Al Viro | f9652e1 | 2013-06-11 08:23:01 +0400 | [diff] [blame] | 3548 | const struct open_flags *op) |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3549 | { |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3550 | struct nameidata nd; |
Al Viro | f9652e1 | 2013-06-11 08:23:01 +0400 | [diff] [blame] | 3551 | int flags = op->lookup_flags; |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3552 | struct file *filp; |
| 3553 | |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3554 | set_nameidata(&nd, dfd, pathname); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3555 | filp = path_openat(&nd, op, flags | LOOKUP_RCU); |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3556 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3557 | filp = path_openat(&nd, op, flags); |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3558 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3559 | filp = path_openat(&nd, op, flags | LOOKUP_REVAL); |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3560 | restore_nameidata(); |
Al Viro | 13aab42 | 2011-02-23 17:54:08 -0500 | [diff] [blame] | 3561 | return filp; |
| 3562 | } |
| 3563 | |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3564 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
Al Viro | f9652e1 | 2013-06-11 08:23:01 +0400 | [diff] [blame] | 3565 | const char *name, const struct open_flags *op) |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3566 | { |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3567 | struct nameidata nd; |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3568 | struct file *file; |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 3569 | struct filename *filename; |
Al Viro | f9652e1 | 2013-06-11 08:23:01 +0400 | [diff] [blame] | 3570 | int flags = op->lookup_flags | LOOKUP_ROOT; |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3571 | |
| 3572 | nd.root.mnt = mnt; |
| 3573 | nd.root.dentry = dentry; |
| 3574 | |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 3575 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3576 | return ERR_PTR(-ELOOP); |
| 3577 | |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 3578 | filename = getname_kernel(name); |
Viresh Kumar | a1c8368 | 2015-08-12 15:59:44 +0530 | [diff] [blame] | 3579 | if (IS_ERR(filename)) |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 3580 | return ERR_CAST(filename); |
| 3581 | |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3582 | set_nameidata(&nd, -1, filename); |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3583 | file = path_openat(&nd, op, flags | LOOKUP_RCU); |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3584 | if (unlikely(file == ERR_PTR(-ECHILD))) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3585 | file = path_openat(&nd, op, flags); |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3586 | if (unlikely(file == ERR_PTR(-ESTALE))) |
Al Viro | c8a53ee | 2015-05-12 18:43:07 -0400 | [diff] [blame] | 3587 | file = path_openat(&nd, op, flags | LOOKUP_REVAL); |
Al Viro | 9883d18 | 2015-05-13 07:28:08 -0400 | [diff] [blame] | 3588 | restore_nameidata(); |
Paul Moore | 5168910 | 2015-01-22 00:00:03 -0500 | [diff] [blame] | 3589 | putname(filename); |
Al Viro | 73d049a | 2011-03-11 12:08:24 -0500 | [diff] [blame] | 3590 | return file; |
| 3591 | } |
| 3592 | |
Al Viro | fa14a0b | 2015-01-22 02:16:49 -0500 | [diff] [blame] | 3593 | static struct dentry *filename_create(int dfd, struct filename *name, |
Jeff Layton | 1ac12b4 | 2012-12-11 12:10:06 -0500 | [diff] [blame] | 3594 | struct path *path, unsigned int lookup_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3595 | { |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3596 | struct dentry *dentry = ERR_PTR(-EEXIST); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3597 | struct qstr last; |
| 3598 | int type; |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3599 | int err2; |
Jeff Layton | 1ac12b4 | 2012-12-11 12:10:06 -0500 | [diff] [blame] | 3600 | int error; |
| 3601 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); |
| 3602 | |
| 3603 | /* |
| 3604 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any |
| 3605 | * other flags passed in are ignored! |
| 3606 | */ |
| 3607 | lookup_flags &= LOOKUP_REVAL; |
| 3608 | |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 3609 | name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); |
| 3610 | if (IS_ERR(name)) |
| 3611 | return ERR_CAST(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3612 | |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3613 | /* |
| 3614 | * Yucky last component or no last component at all? |
| 3615 | * (foo/., foo/.., /////) |
| 3616 | */ |
Al Viro | 5c31b6c | 2015-05-12 17:32:54 -0400 | [diff] [blame] | 3617 | if (unlikely(type != LAST_NORM)) |
Al Viro | ed75e95 | 2011-06-27 16:53:43 -0400 | [diff] [blame] | 3618 | goto out; |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3619 | |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3620 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3621 | err2 = mnt_want_write(path->mnt); |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3622 | /* |
| 3623 | * Do the final lookup. |
| 3624 | */ |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3625 | lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3626 | inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3627 | dentry = __lookup_hash(&last, path->dentry, lookup_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3628 | if (IS_ERR(dentry)) |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3629 | goto unlock; |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3630 | |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3631 | error = -EEXIST; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 3632 | if (d_is_positive(dentry)) |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3633 | goto fail; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 3634 | |
Christoph Hellwig | c663e5d | 2005-06-23 00:09:49 -0700 | [diff] [blame] | 3635 | /* |
| 3636 | * Special case - lookup gave negative, but... we had foo/bar/ |
| 3637 | * From the vfs_mknod() POV we just have a negative dentry - |
| 3638 | * all is fine. Let's be bastards - you had / on the end, you've |
| 3639 | * been asking for (non-existent) directory. -ENOENT for you. |
| 3640 | */ |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3641 | if (unlikely(!is_dir && last.name[last.len])) { |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3642 | error = -ENOENT; |
Al Viro | ed75e95 | 2011-06-27 16:53:43 -0400 | [diff] [blame] | 3643 | goto fail; |
Al Viro | e9baf6e | 2008-05-15 04:49:12 -0400 | [diff] [blame] | 3644 | } |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3645 | if (unlikely(err2)) { |
| 3646 | error = err2; |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3647 | goto fail; |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3648 | } |
Al Viro | 181c37b | 2015-05-12 17:21:25 -0400 | [diff] [blame] | 3649 | putname(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3650 | return dentry; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3651 | fail: |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3652 | dput(dentry); |
| 3653 | dentry = ERR_PTR(error); |
| 3654 | unlock: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3655 | inode_unlock(path->dentry->d_inode); |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3656 | if (!err2) |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3657 | mnt_drop_write(path->mnt); |
Al Viro | ed75e95 | 2011-06-27 16:53:43 -0400 | [diff] [blame] | 3658 | out: |
Al Viro | 391172c | 2015-05-09 11:19:16 -0400 | [diff] [blame] | 3659 | path_put(path); |
Al Viro | 181c37b | 2015-05-12 17:21:25 -0400 | [diff] [blame] | 3660 | putname(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3661 | return dentry; |
| 3662 | } |
Al Viro | fa14a0b | 2015-01-22 02:16:49 -0500 | [diff] [blame] | 3663 | |
| 3664 | struct dentry *kern_path_create(int dfd, const char *pathname, |
| 3665 | struct path *path, unsigned int lookup_flags) |
| 3666 | { |
Al Viro | 181c37b | 2015-05-12 17:21:25 -0400 | [diff] [blame] | 3667 | return filename_create(dfd, getname_kernel(pathname), |
| 3668 | path, lookup_flags); |
Al Viro | fa14a0b | 2015-01-22 02:16:49 -0500 | [diff] [blame] | 3669 | } |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3670 | EXPORT_SYMBOL(kern_path_create); |
| 3671 | |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 3672 | void done_path_create(struct path *path, struct dentry *dentry) |
| 3673 | { |
| 3674 | dput(dentry); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3675 | inode_unlock(path->dentry->d_inode); |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3676 | mnt_drop_write(path->mnt); |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 3677 | path_put(path); |
| 3678 | } |
| 3679 | EXPORT_SYMBOL(done_path_create); |
| 3680 | |
Al Viro | 520ae68 | 2015-05-13 07:00:28 -0400 | [diff] [blame] | 3681 | inline struct dentry *user_path_create(int dfd, const char __user *pathname, |
Jeff Layton | 1ac12b4 | 2012-12-11 12:10:06 -0500 | [diff] [blame] | 3682 | struct path *path, unsigned int lookup_flags) |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3683 | { |
Al Viro | 181c37b | 2015-05-12 17:21:25 -0400 | [diff] [blame] | 3684 | return filename_create(dfd, getname(pathname), path, lookup_flags); |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3685 | } |
| 3686 | EXPORT_SYMBOL(user_path_create); |
| 3687 | |
Al Viro | 1a67aaf | 2011-07-26 01:52:52 -0400 | [diff] [blame] | 3688 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3689 | { |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 3690 | int error = may_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3691 | |
| 3692 | if (error) |
| 3693 | return error; |
| 3694 | |
Christian Brauner | 94f8200 | 2018-07-05 17:51:20 +0200 | [diff] [blame] | 3695 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3696 | return -EPERM; |
| 3697 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 3698 | if (!dir->i_op->mknod) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3699 | return -EPERM; |
| 3700 | |
Serge E. Hallyn | 08ce5f1 | 2008-04-29 01:00:10 -0700 | [diff] [blame] | 3701 | error = devcgroup_inode_mknod(mode, dev); |
| 3702 | if (error) |
| 3703 | return error; |
| 3704 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3705 | error = security_inode_mknod(dir, dentry, mode, dev); |
| 3706 | if (error) |
| 3707 | return error; |
| 3708 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3709 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
Stephen Smalley | a74574a | 2005-09-09 13:01:44 -0700 | [diff] [blame] | 3710 | if (!error) |
Amy Griffis | f38aa94 | 2005-11-03 15:57:06 +0000 | [diff] [blame] | 3711 | fsnotify_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3712 | return error; |
| 3713 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 3714 | EXPORT_SYMBOL(vfs_mknod); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3715 | |
Al Viro | f69aac0 | 2011-07-26 04:31:40 -0400 | [diff] [blame] | 3716 | static int may_mknod(umode_t mode) |
Dave Hansen | 463c319 | 2008-02-15 14:37:57 -0800 | [diff] [blame] | 3717 | { |
| 3718 | switch (mode & S_IFMT) { |
| 3719 | case S_IFREG: |
| 3720 | case S_IFCHR: |
| 3721 | case S_IFBLK: |
| 3722 | case S_IFIFO: |
| 3723 | case S_IFSOCK: |
| 3724 | case 0: /* zero mode translates to S_IFREG */ |
| 3725 | return 0; |
| 3726 | case S_IFDIR: |
| 3727 | return -EPERM; |
| 3728 | default: |
| 3729 | return -EINVAL; |
| 3730 | } |
| 3731 | } |
| 3732 | |
Dominik Brodowski | 87c4e19 | 2018-03-11 11:34:50 +0100 | [diff] [blame] | 3733 | long do_mknodat(int dfd, const char __user *filename, umode_t mode, |
| 3734 | unsigned int dev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3735 | { |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 3736 | struct dentry *dentry; |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3737 | struct path path; |
| 3738 | int error; |
Jeff Layton | 972567f | 2012-12-20 16:00:10 -0500 | [diff] [blame] | 3739 | unsigned int lookup_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3740 | |
Al Viro | 8e4bfca | 2012-07-20 01:17:26 +0400 | [diff] [blame] | 3741 | error = may_mknod(mode); |
| 3742 | if (error) |
| 3743 | return error; |
Jeff Layton | 972567f | 2012-12-20 16:00:10 -0500 | [diff] [blame] | 3744 | retry: |
| 3745 | dentry = user_path_create(dfd, filename, &path, lookup_flags); |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3746 | if (IS_ERR(dentry)) |
| 3747 | return PTR_ERR(dentry); |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 3748 | |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3749 | if (!IS_POSIXACL(path.dentry->d_inode)) |
Al Viro | ce3b0f8 | 2009-03-29 19:08:22 -0400 | [diff] [blame] | 3750 | mode &= ~current_umask(); |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3751 | error = security_path_mknod(&path, dentry, mode, dev); |
Kentaro Takeda | be6d3e5 | 2008-12-17 13:24:15 +0900 | [diff] [blame] | 3752 | if (error) |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3753 | goto out; |
Dave Hansen | 463c319 | 2008-02-15 14:37:57 -0800 | [diff] [blame] | 3754 | switch (mode & S_IFMT) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3755 | case 0: case S_IFREG: |
Al Viro | 312b63f | 2012-06-10 18:09:36 -0400 | [diff] [blame] | 3756 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
Mimi Zohar | 05d1a71 | 2016-02-29 19:52:05 -0500 | [diff] [blame] | 3757 | if (!error) |
| 3758 | ima_post_path_mknod(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3759 | break; |
| 3760 | case S_IFCHR: case S_IFBLK: |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3761 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3762 | new_decode_dev(dev)); |
| 3763 | break; |
| 3764 | case S_IFIFO: case S_IFSOCK: |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3765 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3766 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3767 | } |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3768 | out: |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 3769 | done_path_create(&path, dentry); |
Jeff Layton | 972567f | 2012-12-20 16:00:10 -0500 | [diff] [blame] | 3770 | if (retry_estale(error, lookup_flags)) { |
| 3771 | lookup_flags |= LOOKUP_REVAL; |
| 3772 | goto retry; |
| 3773 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3774 | return error; |
| 3775 | } |
| 3776 | |
Dominik Brodowski | 87c4e19 | 2018-03-11 11:34:50 +0100 | [diff] [blame] | 3777 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
| 3778 | unsigned int, dev) |
| 3779 | { |
| 3780 | return do_mknodat(dfd, filename, mode, dev); |
| 3781 | } |
| 3782 | |
Al Viro | 8208a22 | 2011-07-25 17:32:17 -0400 | [diff] [blame] | 3783 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 3784 | { |
Dominik Brodowski | 87c4e19 | 2018-03-11 11:34:50 +0100 | [diff] [blame] | 3785 | return do_mknodat(AT_FDCWD, filename, mode, dev); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 3786 | } |
| 3787 | |
Al Viro | 18bb1db | 2011-07-26 01:41:39 -0400 | [diff] [blame] | 3788 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3789 | { |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 3790 | int error = may_create(dir, dentry); |
Al Viro | 8de5277 | 2012-02-06 12:45:27 -0500 | [diff] [blame] | 3791 | unsigned max_links = dir->i_sb->s_max_links; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3792 | |
| 3793 | if (error) |
| 3794 | return error; |
| 3795 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 3796 | if (!dir->i_op->mkdir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3797 | return -EPERM; |
| 3798 | |
| 3799 | mode &= (S_IRWXUGO|S_ISVTX); |
| 3800 | error = security_inode_mkdir(dir, dentry, mode); |
| 3801 | if (error) |
| 3802 | return error; |
| 3803 | |
Al Viro | 8de5277 | 2012-02-06 12:45:27 -0500 | [diff] [blame] | 3804 | if (max_links && dir->i_nlink >= max_links) |
| 3805 | return -EMLINK; |
| 3806 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3807 | error = dir->i_op->mkdir(dir, dentry, mode); |
Stephen Smalley | a74574a | 2005-09-09 13:01:44 -0700 | [diff] [blame] | 3808 | if (!error) |
Amy Griffis | f38aa94 | 2005-11-03 15:57:06 +0000 | [diff] [blame] | 3809 | fsnotify_mkdir(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3810 | return error; |
| 3811 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 3812 | EXPORT_SYMBOL(vfs_mkdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3813 | |
Dominik Brodowski | 0101db7 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 3814 | long do_mkdirat(int dfd, const char __user *pathname, umode_t mode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3815 | { |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 3816 | struct dentry *dentry; |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3817 | struct path path; |
| 3818 | int error; |
Jeff Layton | b76d8b8 | 2012-12-20 16:04:09 -0500 | [diff] [blame] | 3819 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3820 | |
Jeff Layton | b76d8b8 | 2012-12-20 16:04:09 -0500 | [diff] [blame] | 3821 | retry: |
| 3822 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 3823 | if (IS_ERR(dentry)) |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3824 | return PTR_ERR(dentry); |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 3825 | |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3826 | if (!IS_POSIXACL(path.dentry->d_inode)) |
Al Viro | ce3b0f8 | 2009-03-29 19:08:22 -0400 | [diff] [blame] | 3827 | mode &= ~current_umask(); |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 3828 | error = security_path_mkdir(&path, dentry, mode); |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 3829 | if (!error) |
| 3830 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 3831 | done_path_create(&path, dentry); |
Jeff Layton | b76d8b8 | 2012-12-20 16:04:09 -0500 | [diff] [blame] | 3832 | if (retry_estale(error, lookup_flags)) { |
| 3833 | lookup_flags |= LOOKUP_REVAL; |
| 3834 | goto retry; |
| 3835 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3836 | return error; |
| 3837 | } |
| 3838 | |
Dominik Brodowski | 0101db7 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 3839 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
| 3840 | { |
| 3841 | return do_mkdirat(dfd, pathname, mode); |
| 3842 | } |
| 3843 | |
Al Viro | a218d0f | 2011-11-21 14:59:34 -0500 | [diff] [blame] | 3844 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 3845 | { |
Dominik Brodowski | 0101db7 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 3846 | return do_mkdirat(AT_FDCWD, pathname, mode); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 3847 | } |
| 3848 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3849 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
| 3850 | { |
| 3851 | int error = may_delete(dir, dentry, 1); |
| 3852 | |
| 3853 | if (error) |
| 3854 | return error; |
| 3855 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 3856 | if (!dir->i_op->rmdir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3857 | return -EPERM; |
| 3858 | |
Al Viro | 1d2ef59 | 2011-09-14 18:55:41 +0100 | [diff] [blame] | 3859 | dget(dentry); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3860 | inode_lock(dentry->d_inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3861 | |
Sage Weil | 912dbc1 | 2011-05-24 13:06:11 -0700 | [diff] [blame] | 3862 | error = -EBUSY; |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 3863 | if (is_local_mountpoint(dentry)) |
Sage Weil | 912dbc1 | 2011-05-24 13:06:11 -0700 | [diff] [blame] | 3864 | goto out; |
| 3865 | |
| 3866 | error = security_inode_rmdir(dir, dentry); |
| 3867 | if (error) |
| 3868 | goto out; |
| 3869 | |
| 3870 | error = dir->i_op->rmdir(dir, dentry); |
| 3871 | if (error) |
| 3872 | goto out; |
| 3873 | |
Al Viro | 8767712 | 2018-05-27 16:23:51 -0400 | [diff] [blame] | 3874 | shrink_dcache_parent(dentry); |
Sage Weil | 912dbc1 | 2011-05-24 13:06:11 -0700 | [diff] [blame] | 3875 | dentry->d_inode->i_flags |= S_DEAD; |
| 3876 | dont_mount(dentry); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 3877 | detach_mounts(dentry); |
Amir Goldstein | 116b973 | 2019-05-26 17:34:02 +0300 | [diff] [blame] | 3878 | fsnotify_rmdir(dir, dentry); |
Sage Weil | 912dbc1 | 2011-05-24 13:06:11 -0700 | [diff] [blame] | 3879 | |
| 3880 | out: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3881 | inode_unlock(dentry->d_inode); |
Al Viro | 1d2ef59 | 2011-09-14 18:55:41 +0100 | [diff] [blame] | 3882 | dput(dentry); |
Sage Weil | 912dbc1 | 2011-05-24 13:06:11 -0700 | [diff] [blame] | 3883 | if (!error) |
| 3884 | d_delete(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3885 | return error; |
| 3886 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 3887 | EXPORT_SYMBOL(vfs_rmdir); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3888 | |
Dominik Brodowski | f459dffa | 2018-03-11 11:34:48 +0100 | [diff] [blame] | 3889 | long do_rmdir(int dfd, const char __user *pathname) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3890 | { |
| 3891 | int error = 0; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 3892 | struct filename *name; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3893 | struct dentry *dentry; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3894 | struct path path; |
| 3895 | struct qstr last; |
| 3896 | int type; |
Jeff Layton | c6ee920 | 2012-12-20 16:28:33 -0500 | [diff] [blame] | 3897 | unsigned int lookup_flags = 0; |
| 3898 | retry: |
Al Viro | c1d4dd2 | 2016-06-05 16:38:18 -0400 | [diff] [blame] | 3899 | name = filename_parentat(dfd, getname(pathname), lookup_flags, |
| 3900 | &path, &last, &type); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 3901 | if (IS_ERR(name)) |
| 3902 | return PTR_ERR(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3903 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3904 | switch (type) { |
OGAWA Hirofumi | 0612d9f | 2008-10-16 07:50:29 +0900 | [diff] [blame] | 3905 | case LAST_DOTDOT: |
| 3906 | error = -ENOTEMPTY; |
| 3907 | goto exit1; |
| 3908 | case LAST_DOT: |
| 3909 | error = -EINVAL; |
| 3910 | goto exit1; |
| 3911 | case LAST_ROOT: |
| 3912 | error = -EBUSY; |
| 3913 | goto exit1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3914 | } |
OGAWA Hirofumi | 0612d9f | 2008-10-16 07:50:29 +0900 | [diff] [blame] | 3915 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3916 | error = mnt_want_write(path.mnt); |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3917 | if (error) |
| 3918 | goto exit1; |
OGAWA Hirofumi | 0612d9f | 2008-10-16 07:50:29 +0900 | [diff] [blame] | 3919 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3920 | inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3921 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3922 | error = PTR_ERR(dentry); |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 3923 | if (IS_ERR(dentry)) |
| 3924 | goto exit2; |
Theodore Ts'o | e6bc45d | 2011-06-06 19:19:40 -0400 | [diff] [blame] | 3925 | if (!dentry->d_inode) { |
| 3926 | error = -ENOENT; |
| 3927 | goto exit3; |
| 3928 | } |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3929 | error = security_path_rmdir(&path, dentry); |
Kentaro Takeda | be6d3e5 | 2008-12-17 13:24:15 +0900 | [diff] [blame] | 3930 | if (error) |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 3931 | goto exit3; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3932 | error = vfs_rmdir(path.dentry->d_inode, dentry); |
Dave Hansen | 0622753 | 2008-02-15 14:37:34 -0800 | [diff] [blame] | 3933 | exit3: |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 3934 | dput(dentry); |
| 3935 | exit2: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3936 | inode_unlock(path.dentry->d_inode); |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3937 | mnt_drop_write(path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3938 | exit1: |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 3939 | path_put(&path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3940 | putname(name); |
Jeff Layton | c6ee920 | 2012-12-20 16:28:33 -0500 | [diff] [blame] | 3941 | if (retry_estale(error, lookup_flags)) { |
| 3942 | lookup_flags |= LOOKUP_REVAL; |
| 3943 | goto retry; |
| 3944 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3945 | return error; |
| 3946 | } |
| 3947 | |
Heiko Carstens | 3cdad42 | 2009-01-14 14:14:22 +0100 | [diff] [blame] | 3948 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 3949 | { |
| 3950 | return do_rmdir(AT_FDCWD, pathname); |
| 3951 | } |
| 3952 | |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 3953 | /** |
| 3954 | * vfs_unlink - unlink a filesystem object |
| 3955 | * @dir: parent directory |
| 3956 | * @dentry: victim |
| 3957 | * @delegated_inode: returns victim inode, if the inode is delegated. |
| 3958 | * |
| 3959 | * The caller must hold dir->i_mutex. |
| 3960 | * |
| 3961 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and |
| 3962 | * return a reference to the inode in delegated_inode. The caller |
| 3963 | * should then break the delegation on that inode and retry. Because |
| 3964 | * breaking a delegation may take a long time, the caller should drop |
| 3965 | * dir->i_mutex before doing so. |
| 3966 | * |
| 3967 | * Alternatively, a caller may pass NULL for delegated_inode. This may |
| 3968 | * be appropriate for callers that expect the underlying filesystem not |
| 3969 | * to be NFS exported. |
| 3970 | */ |
| 3971 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3972 | { |
J. Bruce Fields | 9accbb9 | 2012-08-28 07:03:24 -0400 | [diff] [blame] | 3973 | struct inode *target = dentry->d_inode; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3974 | int error = may_delete(dir, dentry, 0); |
| 3975 | |
| 3976 | if (error) |
| 3977 | return error; |
| 3978 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 3979 | if (!dir->i_op->unlink) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3980 | return -EPERM; |
| 3981 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 3982 | inode_lock(target); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 3983 | if (is_local_mountpoint(dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3984 | error = -EBUSY; |
| 3985 | else { |
| 3986 | error = security_inode_unlink(dir, dentry); |
Al Viro | bec1052 | 2010-03-03 14:12:08 -0500 | [diff] [blame] | 3987 | if (!error) { |
J. Bruce Fields | 5a14696 | 2012-08-28 07:50:40 -0700 | [diff] [blame] | 3988 | error = try_break_deleg(target, delegated_inode); |
| 3989 | if (error) |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 3990 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3991 | error = dir->i_op->unlink(dir, dentry); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 3992 | if (!error) { |
Al Viro | d83c49f | 2010-04-30 17:17:09 -0400 | [diff] [blame] | 3993 | dont_mount(dentry); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 3994 | detach_mounts(dentry); |
Amir Goldstein | 116b973 | 2019-05-26 17:34:02 +0300 | [diff] [blame] | 3995 | fsnotify_unlink(dir, dentry); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 3996 | } |
Al Viro | bec1052 | 2010-03-03 14:12:08 -0500 | [diff] [blame] | 3997 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3998 | } |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 3999 | out: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4000 | inode_unlock(target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4001 | |
| 4002 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ |
| 4003 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { |
J. Bruce Fields | 9accbb9 | 2012-08-28 07:03:24 -0400 | [diff] [blame] | 4004 | fsnotify_link_count(target); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4005 | d_delete(dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4006 | } |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 4007 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4008 | return error; |
| 4009 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4010 | EXPORT_SYMBOL(vfs_unlink); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4011 | |
| 4012 | /* |
| 4013 | * Make sure that the actual truncation of the file will occur outside its |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 4014 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4015 | * writeout happening, and we don't want to prevent access to the directory |
| 4016 | * while waiting on the I/O. |
| 4017 | */ |
Christoph Hellwig | da2f136 | 2017-11-04 13:44:45 +0300 | [diff] [blame] | 4018 | long do_unlinkat(int dfd, struct filename *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4019 | { |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4020 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4021 | struct dentry *dentry; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4022 | struct path path; |
| 4023 | struct qstr last; |
| 4024 | int type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4025 | struct inode *inode = NULL; |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 4026 | struct inode *delegated_inode = NULL; |
Jeff Layton | 5d18f81 | 2012-12-20 16:38:04 -0500 | [diff] [blame] | 4027 | unsigned int lookup_flags = 0; |
| 4028 | retry: |
Christoph Hellwig | da2f136 | 2017-11-04 13:44:45 +0300 | [diff] [blame] | 4029 | name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4030 | if (IS_ERR(name)) |
| 4031 | return PTR_ERR(name); |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4032 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4033 | error = -EISDIR; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4034 | if (type != LAST_NORM) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4035 | goto exit1; |
OGAWA Hirofumi | 0612d9f | 2008-10-16 07:50:29 +0900 | [diff] [blame] | 4036 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4037 | error = mnt_want_write(path.mnt); |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 4038 | if (error) |
| 4039 | goto exit1; |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 4040 | retry_deleg: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4041 | inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4042 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4043 | error = PTR_ERR(dentry); |
| 4044 | if (!IS_ERR(dentry)) { |
| 4045 | /* Why not before? Because we want correct error value */ |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4046 | if (last.name[last.len]) |
Török Edwin | 50338b8 | 2011-06-16 00:06:14 +0300 | [diff] [blame] | 4047 | goto slashes; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4048 | inode = dentry->d_inode; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 4049 | if (d_is_negative(dentry)) |
Theodore Ts'o | e6bc45d | 2011-06-06 19:19:40 -0400 | [diff] [blame] | 4050 | goto slashes; |
| 4051 | ihold(inode); |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4052 | error = security_path_unlink(&path, dentry); |
Kentaro Takeda | be6d3e5 | 2008-12-17 13:24:15 +0900 | [diff] [blame] | 4053 | if (error) |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 4054 | goto exit2; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4055 | error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 4056 | exit2: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4057 | dput(dentry); |
| 4058 | } |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4059 | inode_unlock(path.dentry->d_inode); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4060 | if (inode) |
| 4061 | iput(inode); /* truncate the inode here */ |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 4062 | inode = NULL; |
| 4063 | if (delegated_inode) { |
J. Bruce Fields | 5a14696 | 2012-08-28 07:50:40 -0700 | [diff] [blame] | 4064 | error = break_deleg_wait(&delegated_inode); |
J. Bruce Fields | b21996e | 2011-09-20 09:14:34 -0400 | [diff] [blame] | 4065 | if (!error) |
| 4066 | goto retry_deleg; |
| 4067 | } |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4068 | mnt_drop_write(path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4069 | exit1: |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4070 | path_put(&path); |
Jeff Layton | 5d18f81 | 2012-12-20 16:38:04 -0500 | [diff] [blame] | 4071 | if (retry_estale(error, lookup_flags)) { |
| 4072 | lookup_flags |= LOOKUP_REVAL; |
| 4073 | inode = NULL; |
| 4074 | goto retry; |
| 4075 | } |
Christoph Hellwig | da2f136 | 2017-11-04 13:44:45 +0300 | [diff] [blame] | 4076 | putname(name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4077 | return error; |
| 4078 | |
| 4079 | slashes: |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 4080 | if (d_is_negative(dentry)) |
| 4081 | error = -ENOENT; |
Miklos Szeredi | 44b1d53 | 2014-04-01 17:08:41 +0200 | [diff] [blame] | 4082 | else if (d_is_dir(dentry)) |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 4083 | error = -EISDIR; |
| 4084 | else |
| 4085 | error = -ENOTDIR; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4086 | goto exit2; |
| 4087 | } |
| 4088 | |
Heiko Carstens | 2e4d092 | 2009-01-14 14:14:31 +0100 | [diff] [blame] | 4089 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4090 | { |
| 4091 | if ((flag & ~AT_REMOVEDIR) != 0) |
| 4092 | return -EINVAL; |
| 4093 | |
| 4094 | if (flag & AT_REMOVEDIR) |
| 4095 | return do_rmdir(dfd, pathname); |
| 4096 | |
Christoph Hellwig | da2f136 | 2017-11-04 13:44:45 +0300 | [diff] [blame] | 4097 | return do_unlinkat(dfd, getname(pathname)); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4098 | } |
| 4099 | |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 4100 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4101 | { |
Christoph Hellwig | da2f136 | 2017-11-04 13:44:45 +0300 | [diff] [blame] | 4102 | return do_unlinkat(AT_FDCWD, getname(pathname)); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4103 | } |
| 4104 | |
Miklos Szeredi | db2e747 | 2008-06-24 16:50:16 +0200 | [diff] [blame] | 4105 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4106 | { |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 4107 | int error = may_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4108 | |
| 4109 | if (error) |
| 4110 | return error; |
| 4111 | |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 4112 | if (!dir->i_op->symlink) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4113 | return -EPERM; |
| 4114 | |
| 4115 | error = security_inode_symlink(dir, dentry, oldname); |
| 4116 | if (error) |
| 4117 | return error; |
| 4118 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4119 | error = dir->i_op->symlink(dir, dentry, oldname); |
Stephen Smalley | a74574a | 2005-09-09 13:01:44 -0700 | [diff] [blame] | 4120 | if (!error) |
Amy Griffis | f38aa94 | 2005-11-03 15:57:06 +0000 | [diff] [blame] | 4121 | fsnotify_create(dir, dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4122 | return error; |
| 4123 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4124 | EXPORT_SYMBOL(vfs_symlink); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4125 | |
Dominik Brodowski | b724e84 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 4126 | long do_symlinkat(const char __user *oldname, int newdfd, |
| 4127 | const char __user *newname) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4128 | { |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4129 | int error; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4130 | struct filename *from; |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 4131 | struct dentry *dentry; |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 4132 | struct path path; |
Jeff Layton | f46d356 | 2012-12-11 12:10:08 -0500 | [diff] [blame] | 4133 | unsigned int lookup_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4134 | |
| 4135 | from = getname(oldname); |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4136 | if (IS_ERR(from)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4137 | return PTR_ERR(from); |
Jeff Layton | f46d356 | 2012-12-11 12:10:08 -0500 | [diff] [blame] | 4138 | retry: |
| 4139 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 4140 | error = PTR_ERR(dentry); |
| 4141 | if (IS_ERR(dentry)) |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 4142 | goto out_putname; |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 4143 | |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4144 | error = security_path_symlink(&path, dentry, from->name); |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 4145 | if (!error) |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4146 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 4147 | done_path_create(&path, dentry); |
Jeff Layton | f46d356 | 2012-12-11 12:10:08 -0500 | [diff] [blame] | 4148 | if (retry_estale(error, lookup_flags)) { |
| 4149 | lookup_flags |= LOOKUP_REVAL; |
| 4150 | goto retry; |
| 4151 | } |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 4152 | out_putname: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4153 | putname(from); |
| 4154 | return error; |
| 4155 | } |
| 4156 | |
Dominik Brodowski | b724e84 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 4157 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
| 4158 | int, newdfd, const char __user *, newname) |
| 4159 | { |
| 4160 | return do_symlinkat(oldname, newdfd, newname); |
| 4161 | } |
| 4162 | |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 4163 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4164 | { |
Dominik Brodowski | b724e84 | 2018-03-11 11:34:49 +0100 | [diff] [blame] | 4165 | return do_symlinkat(oldname, AT_FDCWD, newname); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4166 | } |
| 4167 | |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4168 | /** |
| 4169 | * vfs_link - create a new link |
| 4170 | * @old_dentry: object to be linked |
| 4171 | * @dir: new parent |
| 4172 | * @new_dentry: where to create the new link |
| 4173 | * @delegated_inode: returns inode needing a delegation break |
| 4174 | * |
| 4175 | * The caller must hold dir->i_mutex |
| 4176 | * |
| 4177 | * If vfs_link discovers a delegation on the to-be-linked file in need |
| 4178 | * of breaking, it will return -EWOULDBLOCK and return a reference to the |
| 4179 | * inode in delegated_inode. The caller should then break the delegation |
| 4180 | * and retry. Because breaking a delegation may take a long time, the |
| 4181 | * caller should drop the i_mutex before doing so. |
| 4182 | * |
| 4183 | * Alternatively, a caller may pass NULL for delegated_inode. This may |
| 4184 | * be appropriate for callers that expect the underlying filesystem not |
| 4185 | * to be NFS exported. |
| 4186 | */ |
| 4187 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4188 | { |
| 4189 | struct inode *inode = old_dentry->d_inode; |
Al Viro | 8de5277 | 2012-02-06 12:45:27 -0500 | [diff] [blame] | 4190 | unsigned max_links = dir->i_sb->s_max_links; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4191 | int error; |
| 4192 | |
| 4193 | if (!inode) |
| 4194 | return -ENOENT; |
| 4195 | |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 4196 | error = may_create(dir, new_dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4197 | if (error) |
| 4198 | return error; |
| 4199 | |
| 4200 | if (dir->i_sb != inode->i_sb) |
| 4201 | return -EXDEV; |
| 4202 | |
| 4203 | /* |
| 4204 | * A link to an append-only or immutable file cannot be created. |
| 4205 | */ |
| 4206 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
| 4207 | return -EPERM; |
Eric W. Biederman | 0bd23d09 | 2016-06-29 14:54:46 -0500 | [diff] [blame] | 4208 | /* |
| 4209 | * Updating the link count will likely cause i_uid and i_gid to |
| 4210 | * be writen back improperly if their true value is unknown to |
| 4211 | * the vfs. |
| 4212 | */ |
| 4213 | if (HAS_UNMAPPED_ID(inode)) |
| 4214 | return -EPERM; |
Al Viro | acfa438 | 2008-12-04 10:06:33 -0500 | [diff] [blame] | 4215 | if (!dir->i_op->link) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4216 | return -EPERM; |
Tetsuo Handa | 7e79eed | 2008-06-24 16:50:15 +0200 | [diff] [blame] | 4217 | if (S_ISDIR(inode->i_mode)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4218 | return -EPERM; |
| 4219 | |
| 4220 | error = security_inode_link(old_dentry, dir, new_dentry); |
| 4221 | if (error) |
| 4222 | return error; |
| 4223 | |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4224 | inode_lock(inode); |
Aneesh Kumar K.V | aae8a97 | 2011-01-29 18:43:27 +0530 | [diff] [blame] | 4225 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
Al Viro | f4e0c30 | 2013-06-11 08:34:36 +0400 | [diff] [blame] | 4226 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
Aneesh Kumar K.V | aae8a97 | 2011-01-29 18:43:27 +0530 | [diff] [blame] | 4227 | error = -ENOENT; |
Al Viro | 8de5277 | 2012-02-06 12:45:27 -0500 | [diff] [blame] | 4228 | else if (max_links && inode->i_nlink >= max_links) |
| 4229 | error = -EMLINK; |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4230 | else { |
| 4231 | error = try_break_deleg(inode, delegated_inode); |
| 4232 | if (!error) |
| 4233 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
| 4234 | } |
Al Viro | f4e0c30 | 2013-06-11 08:34:36 +0400 | [diff] [blame] | 4235 | |
| 4236 | if (!error && (inode->i_state & I_LINKABLE)) { |
| 4237 | spin_lock(&inode->i_lock); |
| 4238 | inode->i_state &= ~I_LINKABLE; |
| 4239 | spin_unlock(&inode->i_lock); |
| 4240 | } |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4241 | inode_unlock(inode); |
Stephen Smalley | e31e14e | 2005-09-09 13:01:45 -0700 | [diff] [blame] | 4242 | if (!error) |
Tetsuo Handa | 7e79eed | 2008-06-24 16:50:15 +0200 | [diff] [blame] | 4243 | fsnotify_link(dir, inode, new_dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4244 | return error; |
| 4245 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4246 | EXPORT_SYMBOL(vfs_link); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4247 | |
| 4248 | /* |
| 4249 | * Hardlinks are often used in delicate situations. We avoid |
| 4250 | * security-related surprises by not following symlinks on the |
| 4251 | * newname. --KAB |
| 4252 | * |
| 4253 | * We don't follow them on the oldname either to be compatible |
| 4254 | * with linux 2.0, and to avoid hard-linking to directories |
| 4255 | * and other special files. --ADM |
| 4256 | */ |
Dominik Brodowski | 46ea89e | 2018-03-11 11:34:53 +0100 | [diff] [blame] | 4257 | int do_linkat(int olddfd, const char __user *oldname, int newdfd, |
| 4258 | const char __user *newname, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4259 | { |
| 4260 | struct dentry *new_dentry; |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 4261 | struct path old_path, new_path; |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4262 | struct inode *delegated_inode = NULL; |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4263 | int how = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4264 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4265 | |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4266 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
Ulrich Drepper | c04030e | 2006-02-24 13:04:21 -0800 | [diff] [blame] | 4267 | return -EINVAL; |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4268 | /* |
Linus Torvalds | f0cc6ff | 2013-08-28 09:18:05 -0700 | [diff] [blame] | 4269 | * To use null names we require CAP_DAC_READ_SEARCH |
| 4270 | * This ensures that not everyone will be able to create |
| 4271 | * handlink using the passed filedescriptor. |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4272 | */ |
Linus Torvalds | f0cc6ff | 2013-08-28 09:18:05 -0700 | [diff] [blame] | 4273 | if (flags & AT_EMPTY_PATH) { |
| 4274 | if (!capable(CAP_DAC_READ_SEARCH)) |
| 4275 | return -ENOENT; |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4276 | how = LOOKUP_EMPTY; |
Linus Torvalds | f0cc6ff | 2013-08-28 09:18:05 -0700 | [diff] [blame] | 4277 | } |
Ulrich Drepper | c04030e | 2006-02-24 13:04:21 -0800 | [diff] [blame] | 4278 | |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4279 | if (flags & AT_SYMLINK_FOLLOW) |
| 4280 | how |= LOOKUP_FOLLOW; |
Jeff Layton | 442e31c | 2012-12-20 16:15:38 -0500 | [diff] [blame] | 4281 | retry: |
Aneesh Kumar K.V | 11a7b37 | 2011-01-29 18:43:42 +0530 | [diff] [blame] | 4282 | error = user_path_at(olddfd, oldname, how, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4283 | if (error) |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4284 | return error; |
| 4285 | |
Jeff Layton | 442e31c | 2012-12-20 16:15:38 -0500 | [diff] [blame] | 4286 | new_dentry = user_path_create(newdfd, newname, &new_path, |
| 4287 | (how & LOOKUP_REVAL)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4288 | error = PTR_ERR(new_dentry); |
Dave Hansen | 6902d92 | 2006-09-30 23:29:01 -0700 | [diff] [blame] | 4289 | if (IS_ERR(new_dentry)) |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 4290 | goto out; |
| 4291 | |
| 4292 | error = -EXDEV; |
| 4293 | if (old_path.mnt != new_path.mnt) |
| 4294 | goto out_dput; |
Kees Cook | 800179c | 2012-07-25 17:29:07 -0700 | [diff] [blame] | 4295 | error = may_linkat(&old_path); |
| 4296 | if (unlikely(error)) |
| 4297 | goto out_dput; |
Al Viro | dae6ad8 | 2011-06-26 11:50:15 -0400 | [diff] [blame] | 4298 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
Kentaro Takeda | be6d3e5 | 2008-12-17 13:24:15 +0900 | [diff] [blame] | 4299 | if (error) |
Al Viro | a8104a9 | 2012-07-20 02:25:00 +0400 | [diff] [blame] | 4300 | goto out_dput; |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4301 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
Dave Hansen | 75c3f29 | 2008-02-15 14:37:45 -0800 | [diff] [blame] | 4302 | out_dput: |
Al Viro | 921a165 | 2012-07-20 01:15:31 +0400 | [diff] [blame] | 4303 | done_path_create(&new_path, new_dentry); |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4304 | if (delegated_inode) { |
| 4305 | error = break_deleg_wait(&delegated_inode); |
Oleg Drokin | d22e633 | 2014-01-31 15:41:58 -0500 | [diff] [blame] | 4306 | if (!error) { |
| 4307 | path_put(&old_path); |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4308 | goto retry; |
Oleg Drokin | d22e633 | 2014-01-31 15:41:58 -0500 | [diff] [blame] | 4309 | } |
J. Bruce Fields | 146a859 | 2011-09-20 17:14:31 -0400 | [diff] [blame] | 4310 | } |
Jeff Layton | 442e31c | 2012-12-20 16:15:38 -0500 | [diff] [blame] | 4311 | if (retry_estale(error, how)) { |
Oleg Drokin | d22e633 | 2014-01-31 15:41:58 -0500 | [diff] [blame] | 4312 | path_put(&old_path); |
Jeff Layton | 442e31c | 2012-12-20 16:15:38 -0500 | [diff] [blame] | 4313 | how |= LOOKUP_REVAL; |
| 4314 | goto retry; |
| 4315 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4316 | out: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 4317 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4318 | |
| 4319 | return error; |
| 4320 | } |
| 4321 | |
Dominik Brodowski | 46ea89e | 2018-03-11 11:34:53 +0100 | [diff] [blame] | 4322 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
| 4323 | int, newdfd, const char __user *, newname, int, flags) |
| 4324 | { |
| 4325 | return do_linkat(olddfd, oldname, newdfd, newname, flags); |
| 4326 | } |
| 4327 | |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 4328 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4329 | { |
Dominik Brodowski | 46ea89e | 2018-03-11 11:34:53 +0100 | [diff] [blame] | 4330 | return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4331 | } |
| 4332 | |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4333 | /** |
| 4334 | * vfs_rename - rename a filesystem object |
| 4335 | * @old_dir: parent of source |
| 4336 | * @old_dentry: source |
| 4337 | * @new_dir: parent of destination |
| 4338 | * @new_dentry: destination |
| 4339 | * @delegated_inode: returns an inode needing a delegation break |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4340 | * @flags: rename flags |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4341 | * |
| 4342 | * The caller must hold multiple mutexes--see lock_rename()). |
| 4343 | * |
| 4344 | * If vfs_rename discovers a delegation in need of breaking at either |
| 4345 | * the source or destination, it will return -EWOULDBLOCK and return a |
| 4346 | * reference to the inode in delegated_inode. The caller should then |
| 4347 | * break the delegation and retry. Because breaking a delegation may |
| 4348 | * take a long time, the caller should drop all locks before doing |
| 4349 | * so. |
| 4350 | * |
| 4351 | * Alternatively, a caller may pass NULL for delegated_inode. This may |
| 4352 | * be appropriate for callers that expect the underlying filesystem not |
| 4353 | * to be NFS exported. |
| 4354 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4355 | * The worst of all namespace operations - renaming directory. "Perverted" |
| 4356 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... |
| 4357 | * Problems: |
Mauro Carvalho Chehab | 0117d42 | 2017-05-12 07:45:42 -0300 | [diff] [blame] | 4358 | * |
J. Bruce Fields | d03b29a2 | 2014-02-17 16:52:33 -0500 | [diff] [blame] | 4359 | * a) we can get into loop creation. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4360 | * b) race potential - two innocent renames can create a loop together. |
| 4361 | * That's where 4.4 screws up. Current fix: serialization on |
Arjan van de Ven | a11f3a0 | 2006-03-23 03:00:33 -0800 | [diff] [blame] | 4362 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4363 | * story. |
J. Bruce Fields | 6cedba8 | 2012-03-05 11:40:41 -0500 | [diff] [blame] | 4364 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
| 4365 | * and source (if it is not a directory). |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 4366 | * And that - after we got ->i_mutex on parents (until then we don't know |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4367 | * whether the target exists). Solution: try to be smart with locking |
| 4368 | * order for inodes. We rely on the fact that tree topology may change |
Arjan van de Ven | a11f3a0 | 2006-03-23 03:00:33 -0800 | [diff] [blame] | 4369 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4370 | * move will be locked. Thus we can rank directories by the tree |
| 4371 | * (ancestors first) and rank all non-directories after them. |
| 4372 | * That works since everybody except rename does "lock parent, lookup, |
Arjan van de Ven | a11f3a0 | 2006-03-23 03:00:33 -0800 | [diff] [blame] | 4373 | * lock child" and rename is under ->s_vfs_rename_mutex. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4374 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
| 4375 | * has no more than 1 dentry. If "hybrid" objects will ever appear, |
| 4376 | * we'd better make sure that there's no link(2) for them. |
Sage Weil | e4eaac0 | 2011-05-24 13:06:07 -0700 | [diff] [blame] | 4377 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 4378 | * we are removing the target. Solution: we will have to grab ->i_mutex |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4379 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
Adam Buchbinder | c41b20e | 2009-12-11 16:35:39 -0500 | [diff] [blame] | 4380 | * ->i_mutex on parents, which works but leads to some truly excessive |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4381 | * locking]. |
| 4382 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4383 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
J. Bruce Fields | 8e6d782 | 2011-09-20 16:59:58 -0400 | [diff] [blame] | 4384 | struct inode *new_dir, struct dentry *new_dentry, |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4385 | struct inode **delegated_inode, unsigned int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4386 | { |
| 4387 | int error; |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4388 | bool is_dir = d_is_dir(old_dentry); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4389 | struct inode *source = old_dentry->d_inode; |
| 4390 | struct inode *target = new_dentry->d_inode; |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4391 | bool new_is_dir = false; |
| 4392 | unsigned max_links = new_dir->i_sb->s_max_links; |
Al Viro | 49d31c2 | 2017-07-07 14:51:19 -0400 | [diff] [blame] | 4393 | struct name_snapshot old_name; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4394 | |
Miklos Szeredi | 8d3e293 | 2016-12-16 11:02:54 +0100 | [diff] [blame] | 4395 | if (source == target) |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4396 | return 0; |
| 4397 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4398 | error = may_delete(old_dir, old_dentry, is_dir); |
| 4399 | if (error) |
| 4400 | return error; |
| 4401 | |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4402 | if (!target) { |
Miklos Szeredi | a95164d | 2008-07-30 15:08:48 +0200 | [diff] [blame] | 4403 | error = may_create(new_dir, new_dentry); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4404 | } else { |
| 4405 | new_is_dir = d_is_dir(new_dentry); |
| 4406 | |
| 4407 | if (!(flags & RENAME_EXCHANGE)) |
| 4408 | error = may_delete(new_dir, new_dentry, is_dir); |
| 4409 | else |
| 4410 | error = may_delete(new_dir, new_dentry, new_is_dir); |
| 4411 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4412 | if (error) |
| 4413 | return error; |
| 4414 | |
Miklos Szeredi | 2773bf0 | 2016-09-27 11:03:58 +0200 | [diff] [blame] | 4415 | if (!old_dir->i_op->rename) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4416 | return -EPERM; |
| 4417 | |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4418 | /* |
| 4419 | * If we are going to change the parent - check write permissions, |
| 4420 | * we'll need to flip '..'. |
| 4421 | */ |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4422 | if (new_dir != old_dir) { |
| 4423 | if (is_dir) { |
| 4424 | error = inode_permission(source, MAY_WRITE); |
| 4425 | if (error) |
| 4426 | return error; |
| 4427 | } |
| 4428 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { |
| 4429 | error = inode_permission(target, MAY_WRITE); |
| 4430 | if (error) |
| 4431 | return error; |
| 4432 | } |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4433 | } |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 4434 | |
Miklos Szeredi | 0b3974e | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4435 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
| 4436 | flags); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4437 | if (error) |
| 4438 | return error; |
| 4439 | |
Al Viro | 49d31c2 | 2017-07-07 14:51:19 -0400 | [diff] [blame] | 4440 | take_dentry_name_snapshot(&old_name, old_dentry); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4441 | dget(new_dentry); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4442 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4443 | lock_two_nondirectories(source, target); |
| 4444 | else if (target) |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4445 | inode_lock(target); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4446 | |
| 4447 | error = -EBUSY; |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 4448 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4449 | goto out; |
| 4450 | |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4451 | if (max_links && new_dir != old_dir) { |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4452 | error = -EMLINK; |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4453 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4454 | goto out; |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4455 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
| 4456 | old_dir->i_nlink >= max_links) |
| 4457 | goto out; |
| 4458 | } |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4459 | if (!is_dir) { |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4460 | error = try_break_deleg(source, delegated_inode); |
| 4461 | if (error) |
| 4462 | goto out; |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4463 | } |
| 4464 | if (target && !new_is_dir) { |
| 4465 | error = try_break_deleg(target, delegated_inode); |
| 4466 | if (error) |
| 4467 | goto out; |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4468 | } |
Miklos Szeredi | 2773bf0 | 2016-09-27 11:03:58 +0200 | [diff] [blame] | 4469 | error = old_dir->i_op->rename(old_dir, old_dentry, |
Miklos Szeredi | 18fc84d | 2016-09-27 11:03:58 +0200 | [diff] [blame] | 4470 | new_dir, new_dentry, flags); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4471 | if (error) |
| 4472 | goto out; |
| 4473 | |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4474 | if (!(flags & RENAME_EXCHANGE) && target) { |
Al Viro | 8767712 | 2018-05-27 16:23:51 -0400 | [diff] [blame] | 4475 | if (is_dir) { |
| 4476 | shrink_dcache_parent(new_dentry); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4477 | target->i_flags |= S_DEAD; |
Al Viro | 8767712 | 2018-05-27 16:23:51 -0400 | [diff] [blame] | 4478 | } |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4479 | dont_mount(new_dentry); |
Eric W. Biederman | 8ed936b | 2013-10-01 18:33:48 -0700 | [diff] [blame] | 4480 | detach_mounts(new_dentry); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4481 | } |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4482 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
| 4483 | if (!(flags & RENAME_EXCHANGE)) |
| 4484 | d_move(old_dentry, new_dentry); |
| 4485 | else |
| 4486 | d_exchange(old_dentry, new_dentry); |
| 4487 | } |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4488 | out: |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4489 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4490 | unlock_two_nondirectories(source, target); |
| 4491 | else if (target) |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 4492 | inode_unlock(target); |
Miklos Szeredi | bc27027 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4493 | dput(new_dentry); |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4494 | if (!error) { |
Al Viro | f4ec3a3 | 2019-04-26 13:21:24 -0400 | [diff] [blame] | 4495 | fsnotify_move(old_dir, new_dir, &old_name.name, is_dir, |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4496 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
| 4497 | if (flags & RENAME_EXCHANGE) { |
Al Viro | f4ec3a3 | 2019-04-26 13:21:24 -0400 | [diff] [blame] | 4498 | fsnotify_move(new_dir, old_dir, &old_dentry->d_name, |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4499 | new_is_dir, NULL, new_dentry); |
| 4500 | } |
| 4501 | } |
Al Viro | 49d31c2 | 2017-07-07 14:51:19 -0400 | [diff] [blame] | 4502 | release_dentry_name_snapshot(&old_name); |
Robert Love | 0eeca28 | 2005-07-12 17:06:03 -0400 | [diff] [blame] | 4503 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4504 | return error; |
| 4505 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4506 | EXPORT_SYMBOL(vfs_rename); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4507 | |
Dominik Brodowski | ee81feb | 2018-03-11 11:34:28 +0100 | [diff] [blame] | 4508 | static int do_renameat2(int olddfd, const char __user *oldname, int newdfd, |
| 4509 | const char __user *newname, unsigned int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4510 | { |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4511 | struct dentry *old_dentry, *new_dentry; |
| 4512 | struct dentry *trap; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4513 | struct path old_path, new_path; |
| 4514 | struct qstr old_last, new_last; |
| 4515 | int old_type, new_type; |
J. Bruce Fields | 8e6d782 | 2011-09-20 16:59:58 -0400 | [diff] [blame] | 4516 | struct inode *delegated_inode = NULL; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4517 | struct filename *from; |
| 4518 | struct filename *to; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4519 | unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; |
Jeff Layton | c6a9428 | 2012-12-11 12:10:10 -0500 | [diff] [blame] | 4520 | bool should_retry = false; |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4521 | int error; |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4522 | |
Miklos Szeredi | 0d7a855 | 2014-10-24 00:14:37 +0200 | [diff] [blame] | 4523 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4524 | return -EINVAL; |
| 4525 | |
Miklos Szeredi | 0d7a855 | 2014-10-24 00:14:37 +0200 | [diff] [blame] | 4526 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
| 4527 | (flags & RENAME_EXCHANGE)) |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4528 | return -EINVAL; |
| 4529 | |
Miklos Szeredi | 0d7a855 | 2014-10-24 00:14:37 +0200 | [diff] [blame] | 4530 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
| 4531 | return -EPERM; |
| 4532 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4533 | if (flags & RENAME_EXCHANGE) |
| 4534 | target_flags = 0; |
| 4535 | |
Jeff Layton | c6a9428 | 2012-12-11 12:10:10 -0500 | [diff] [blame] | 4536 | retry: |
Al Viro | c1d4dd2 | 2016-06-05 16:38:18 -0400 | [diff] [blame] | 4537 | from = filename_parentat(olddfd, getname(oldname), lookup_flags, |
| 4538 | &old_path, &old_last, &old_type); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4539 | if (IS_ERR(from)) { |
| 4540 | error = PTR_ERR(from); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4541 | goto exit; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4542 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4543 | |
Al Viro | c1d4dd2 | 2016-06-05 16:38:18 -0400 | [diff] [blame] | 4544 | to = filename_parentat(newdfd, getname(newname), lookup_flags, |
| 4545 | &new_path, &new_last, &new_type); |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4546 | if (IS_ERR(to)) { |
| 4547 | error = PTR_ERR(to); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4548 | goto exit1; |
Jeff Layton | 91a27b2 | 2012-10-10 15:25:28 -0400 | [diff] [blame] | 4549 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4550 | |
| 4551 | error = -EXDEV; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4552 | if (old_path.mnt != new_path.mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4553 | goto exit2; |
| 4554 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4555 | error = -EBUSY; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4556 | if (old_type != LAST_NORM) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4557 | goto exit2; |
| 4558 | |
Miklos Szeredi | 0a7c393 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4559 | if (flags & RENAME_NOREPLACE) |
| 4560 | error = -EEXIST; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4561 | if (new_type != LAST_NORM) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4562 | goto exit2; |
| 4563 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4564 | error = mnt_want_write(old_path.mnt); |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 4565 | if (error) |
| 4566 | goto exit2; |
| 4567 | |
J. Bruce Fields | 8e6d782 | 2011-09-20 16:59:58 -0400 | [diff] [blame] | 4568 | retry_deleg: |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4569 | trap = lock_rename(new_path.dentry, old_path.dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4570 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4571 | old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4572 | error = PTR_ERR(old_dentry); |
| 4573 | if (IS_ERR(old_dentry)) |
| 4574 | goto exit3; |
| 4575 | /* source must exist */ |
| 4576 | error = -ENOENT; |
David Howells | b18825a | 2013-09-12 19:22:53 +0100 | [diff] [blame] | 4577 | if (d_is_negative(old_dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4578 | goto exit4; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4579 | new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4580 | error = PTR_ERR(new_dentry); |
| 4581 | if (IS_ERR(new_dentry)) |
| 4582 | goto exit4; |
Miklos Szeredi | 0a7c393 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4583 | error = -EEXIST; |
| 4584 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) |
| 4585 | goto exit5; |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4586 | if (flags & RENAME_EXCHANGE) { |
| 4587 | error = -ENOENT; |
| 4588 | if (d_is_negative(new_dentry)) |
| 4589 | goto exit5; |
| 4590 | |
| 4591 | if (!d_is_dir(new_dentry)) { |
| 4592 | error = -ENOTDIR; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4593 | if (new_last.name[new_last.len]) |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4594 | goto exit5; |
| 4595 | } |
| 4596 | } |
Miklos Szeredi | 0a7c393 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4597 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
| 4598 | if (!d_is_dir(old_dentry)) { |
| 4599 | error = -ENOTDIR; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4600 | if (old_last.name[old_last.len]) |
Miklos Szeredi | 0a7c393 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4601 | goto exit5; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4602 | if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) |
Miklos Szeredi | 0a7c393 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4603 | goto exit5; |
| 4604 | } |
| 4605 | /* source should not be ancestor of target */ |
| 4606 | error = -EINVAL; |
| 4607 | if (old_dentry == trap) |
| 4608 | goto exit5; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4609 | /* target should not be an ancestor of source */ |
Miklos Szeredi | da1ce06 | 2014-04-01 17:08:43 +0200 | [diff] [blame] | 4610 | if (!(flags & RENAME_EXCHANGE)) |
| 4611 | error = -ENOTEMPTY; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4612 | if (new_dentry == trap) |
| 4613 | goto exit5; |
| 4614 | |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4615 | error = security_path_rename(&old_path, old_dentry, |
| 4616 | &new_path, new_dentry, flags); |
Kentaro Takeda | be6d3e5 | 2008-12-17 13:24:15 +0900 | [diff] [blame] | 4617 | if (error) |
Jan Kara | c30dabf | 2012-06-12 16:20:30 +0200 | [diff] [blame] | 4618 | goto exit5; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4619 | error = vfs_rename(old_path.dentry->d_inode, old_dentry, |
| 4620 | new_path.dentry->d_inode, new_dentry, |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4621 | &delegated_inode, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4622 | exit5: |
| 4623 | dput(new_dentry); |
| 4624 | exit4: |
| 4625 | dput(old_dentry); |
| 4626 | exit3: |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4627 | unlock_rename(new_path.dentry, old_path.dentry); |
J. Bruce Fields | 8e6d782 | 2011-09-20 16:59:58 -0400 | [diff] [blame] | 4628 | if (delegated_inode) { |
| 4629 | error = break_deleg_wait(&delegated_inode); |
| 4630 | if (!error) |
| 4631 | goto retry_deleg; |
| 4632 | } |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4633 | mnt_drop_write(old_path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4634 | exit2: |
Jeff Layton | c6a9428 | 2012-12-11 12:10:10 -0500 | [diff] [blame] | 4635 | if (retry_estale(error, lookup_flags)) |
| 4636 | should_retry = true; |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4637 | path_put(&new_path); |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4638 | putname(to); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4639 | exit1: |
Al Viro | f5beed7 | 2015-04-30 16:09:11 -0400 | [diff] [blame] | 4640 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4641 | putname(from); |
Jeff Layton | c6a9428 | 2012-12-11 12:10:10 -0500 | [diff] [blame] | 4642 | if (should_retry) { |
| 4643 | should_retry = false; |
| 4644 | lookup_flags |= LOOKUP_REVAL; |
| 4645 | goto retry; |
| 4646 | } |
Al Viro | 2ad94ae | 2008-07-21 09:32:51 -0400 | [diff] [blame] | 4647 | exit: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4648 | return error; |
| 4649 | } |
| 4650 | |
Dominik Brodowski | ee81feb | 2018-03-11 11:34:28 +0100 | [diff] [blame] | 4651 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
| 4652 | int, newdfd, const char __user *, newname, unsigned int, flags) |
| 4653 | { |
| 4654 | return do_renameat2(olddfd, oldname, newdfd, newname, flags); |
| 4655 | } |
| 4656 | |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4657 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
| 4658 | int, newdfd, const char __user *, newname) |
| 4659 | { |
Dominik Brodowski | ee81feb | 2018-03-11 11:34:28 +0100 | [diff] [blame] | 4660 | return do_renameat2(olddfd, oldname, newdfd, newname, 0); |
Miklos Szeredi | 520c8b1 | 2014-04-01 17:08:42 +0200 | [diff] [blame] | 4661 | } |
| 4662 | |
Heiko Carstens | a26eab2 | 2009-01-14 14:14:17 +0100 | [diff] [blame] | 4663 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4664 | { |
Dominik Brodowski | ee81feb | 2018-03-11 11:34:28 +0100 | [diff] [blame] | 4665 | return do_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
Ulrich Drepper | 5590ff0 | 2006-01-18 17:43:53 -0800 | [diff] [blame] | 4666 | } |
| 4667 | |
Miklos Szeredi | 787fb6b | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 4668 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
| 4669 | { |
| 4670 | int error = may_create(dir, dentry); |
| 4671 | if (error) |
| 4672 | return error; |
| 4673 | |
| 4674 | if (!dir->i_op->mknod) |
| 4675 | return -EPERM; |
| 4676 | |
| 4677 | return dir->i_op->mknod(dir, dentry, |
| 4678 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); |
| 4679 | } |
| 4680 | EXPORT_SYMBOL(vfs_whiteout); |
| 4681 | |
Al Viro | 5d826c8 | 2014-03-14 13:42:45 -0400 | [diff] [blame] | 4682 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4683 | { |
Al Viro | 5d826c8 | 2014-03-14 13:42:45 -0400 | [diff] [blame] | 4684 | int len = PTR_ERR(link); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4685 | if (IS_ERR(link)) |
| 4686 | goto out; |
| 4687 | |
| 4688 | len = strlen(link); |
| 4689 | if (len > (unsigned) buflen) |
| 4690 | len = buflen; |
| 4691 | if (copy_to_user(buffer, link, len)) |
| 4692 | len = -EFAULT; |
| 4693 | out: |
| 4694 | return len; |
| 4695 | } |
| 4696 | |
Miklos Szeredi | d60874c | 2016-10-04 14:40:45 +0200 | [diff] [blame] | 4697 | /** |
Miklos Szeredi | fd4a0edf | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4698 | * vfs_readlink - copy symlink body into userspace buffer |
| 4699 | * @dentry: dentry on which to get symbolic link |
| 4700 | * @buffer: user memory pointer |
| 4701 | * @buflen: size of buffer |
| 4702 | * |
| 4703 | * Does not touch atime. That's up to the caller if necessary |
| 4704 | * |
| 4705 | * Does not call security hook. |
| 4706 | */ |
| 4707 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
| 4708 | { |
| 4709 | struct inode *inode = d_inode(dentry); |
Al Viro | f2df5da | 2018-07-19 17:35:51 -0400 | [diff] [blame] | 4710 | DEFINE_DELAYED_CALL(done); |
| 4711 | const char *link; |
| 4712 | int res; |
Miklos Szeredi | fd4a0edf | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4713 | |
Miklos Szeredi | 76fca90 | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4714 | if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) { |
| 4715 | if (unlikely(inode->i_op->readlink)) |
| 4716 | return inode->i_op->readlink(dentry, buffer, buflen); |
Miklos Szeredi | fd4a0edf | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4717 | |
Miklos Szeredi | 76fca90 | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4718 | if (!d_is_symlink(dentry)) |
| 4719 | return -EINVAL; |
| 4720 | |
| 4721 | spin_lock(&inode->i_lock); |
| 4722 | inode->i_opflags |= IOP_DEFAULT_READLINK; |
| 4723 | spin_unlock(&inode->i_lock); |
| 4724 | } |
| 4725 | |
Eric Biggers | 4c4f7c1 | 2019-04-10 13:21:14 -0700 | [diff] [blame] | 4726 | link = READ_ONCE(inode->i_link); |
Al Viro | f2df5da | 2018-07-19 17:35:51 -0400 | [diff] [blame] | 4727 | if (!link) { |
| 4728 | link = inode->i_op->get_link(dentry, inode, &done); |
| 4729 | if (IS_ERR(link)) |
| 4730 | return PTR_ERR(link); |
| 4731 | } |
| 4732 | res = readlink_copy(buffer, buflen, link); |
| 4733 | do_delayed_call(&done); |
| 4734 | return res; |
Miklos Szeredi | fd4a0edf | 2016-12-09 16:45:04 +0100 | [diff] [blame] | 4735 | } |
| 4736 | EXPORT_SYMBOL(vfs_readlink); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4737 | |
Miklos Szeredi | d60874c | 2016-10-04 14:40:45 +0200 | [diff] [blame] | 4738 | /** |
| 4739 | * vfs_get_link - get symlink body |
| 4740 | * @dentry: dentry on which to get symbolic link |
| 4741 | * @done: caller needs to free returned data with this |
| 4742 | * |
| 4743 | * Calls security hook and i_op->get_link() on the supplied inode. |
| 4744 | * |
| 4745 | * It does not touch atime. That's up to the caller if necessary. |
| 4746 | * |
| 4747 | * Does not work on "special" symlinks like /proc/$$/fd/N |
| 4748 | */ |
| 4749 | const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done) |
| 4750 | { |
| 4751 | const char *res = ERR_PTR(-EINVAL); |
| 4752 | struct inode *inode = d_inode(dentry); |
| 4753 | |
| 4754 | if (d_is_symlink(dentry)) { |
| 4755 | res = ERR_PTR(security_inode_readlink(dentry)); |
| 4756 | if (!res) |
| 4757 | res = inode->i_op->get_link(dentry, inode, done); |
| 4758 | } |
| 4759 | return res; |
| 4760 | } |
| 4761 | EXPORT_SYMBOL(vfs_get_link); |
| 4762 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4763 | /* get the link contents into pagecache */ |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4764 | const char *page_get_link(struct dentry *dentry, struct inode *inode, |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4765 | struct delayed_call *callback) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4766 | { |
Duane Griffin | ebd09ab | 2008-12-19 20:47:12 +0000 | [diff] [blame] | 4767 | char *kaddr; |
| 4768 | struct page *page; |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4769 | struct address_space *mapping = inode->i_mapping; |
| 4770 | |
Al Viro | d3883d4 | 2015-11-17 10:41:04 -0500 | [diff] [blame] | 4771 | if (!dentry) { |
| 4772 | page = find_get_page(mapping, 0); |
| 4773 | if (!page) |
| 4774 | return ERR_PTR(-ECHILD); |
| 4775 | if (!PageUptodate(page)) { |
| 4776 | put_page(page); |
| 4777 | return ERR_PTR(-ECHILD); |
| 4778 | } |
| 4779 | } else { |
| 4780 | page = read_mapping_page(mapping, 0, NULL); |
| 4781 | if (IS_ERR(page)) |
| 4782 | return (char*)page; |
| 4783 | } |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4784 | set_delayed_call(callback, page_put_link, page); |
Al Viro | 21fc61c | 2015-11-17 01:07:57 -0500 | [diff] [blame] | 4785 | BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); |
| 4786 | kaddr = page_address(page); |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4787 | nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); |
Duane Griffin | ebd09ab | 2008-12-19 20:47:12 +0000 | [diff] [blame] | 4788 | return kaddr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4789 | } |
| 4790 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4791 | EXPORT_SYMBOL(page_get_link); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4792 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4793 | void page_put_link(void *arg) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4794 | { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4795 | put_page(arg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4796 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4797 | EXPORT_SYMBOL(page_put_link); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4798 | |
Al Viro | aa80dea | 2015-11-16 18:26:34 -0500 | [diff] [blame] | 4799 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
| 4800 | { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4801 | DEFINE_DELAYED_CALL(done); |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4802 | int res = readlink_copy(buffer, buflen, |
| 4803 | page_get_link(dentry, d_inode(dentry), |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 4804 | &done)); |
| 4805 | do_delayed_call(&done); |
Al Viro | aa80dea | 2015-11-16 18:26:34 -0500 | [diff] [blame] | 4806 | return res; |
| 4807 | } |
| 4808 | EXPORT_SYMBOL(page_readlink); |
| 4809 | |
Nick Piggin | 54566b2 | 2009-01-04 12:00:53 -0800 | [diff] [blame] | 4810 | /* |
| 4811 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS |
| 4812 | */ |
| 4813 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4814 | { |
| 4815 | struct address_space *mapping = inode->i_mapping; |
Kirill Korotaev | 0adb25d | 2006-03-11 03:27:13 -0800 | [diff] [blame] | 4816 | struct page *page; |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame] | 4817 | void *fsdata; |
Dmitriy Monakhov | beb497a | 2007-02-16 01:27:18 -0800 | [diff] [blame] | 4818 | int err; |
Tetsuo Handa | c718a97 | 2017-05-08 15:58:59 -0700 | [diff] [blame] | 4819 | unsigned int flags = 0; |
Nick Piggin | 54566b2 | 2009-01-04 12:00:53 -0800 | [diff] [blame] | 4820 | if (nofs) |
| 4821 | flags |= AOP_FLAG_NOFS; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4822 | |
NeilBrown | 7e53cac | 2006-03-25 03:07:57 -0800 | [diff] [blame] | 4823 | retry: |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame] | 4824 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
Nick Piggin | 54566b2 | 2009-01-04 12:00:53 -0800 | [diff] [blame] | 4825 | flags, &page, &fsdata); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4826 | if (err) |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame] | 4827 | goto fail; |
| 4828 | |
Al Viro | 21fc61c | 2015-11-17 01:07:57 -0500 | [diff] [blame] | 4829 | memcpy(page_address(page), symname, len-1); |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame] | 4830 | |
| 4831 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, |
| 4832 | page, fsdata); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4833 | if (err < 0) |
| 4834 | goto fail; |
Nick Piggin | afddba4 | 2007-10-16 01:25:01 -0700 | [diff] [blame] | 4835 | if (err < len-1) |
| 4836 | goto retry; |
| 4837 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4838 | mark_inode_dirty(inode); |
| 4839 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4840 | fail: |
| 4841 | return err; |
| 4842 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4843 | EXPORT_SYMBOL(__page_symlink); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4844 | |
Kirill Korotaev | 0adb25d | 2006-03-11 03:27:13 -0800 | [diff] [blame] | 4845 | int page_symlink(struct inode *inode, const char *symname, int len) |
| 4846 | { |
| 4847 | return __page_symlink(inode, symname, len, |
Michal Hocko | c62d255 | 2015-11-06 16:28:49 -0800 | [diff] [blame] | 4848 | !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); |
Kirill Korotaev | 0adb25d | 2006-03-11 03:27:13 -0800 | [diff] [blame] | 4849 | } |
Al Viro | 4d35950 | 2014-03-14 12:20:17 -0400 | [diff] [blame] | 4850 | EXPORT_SYMBOL(page_symlink); |
Kirill Korotaev | 0adb25d | 2006-03-11 03:27:13 -0800 | [diff] [blame] | 4851 | |
Arjan van de Ven | 92e1d5b | 2007-02-12 00:55:39 -0800 | [diff] [blame] | 4852 | const struct inode_operations page_symlink_inode_operations = { |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 4853 | .get_link = page_get_link, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4854 | }; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4855 | EXPORT_SYMBOL(page_symlink_inode_operations); |