Thomas Gleixner | 328970d | 2019-05-24 12:04:05 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 2 | /* -*- mode: c; c-basic-offset: 8; -*- |
| 3 | * vim: noexpandtab sw=8 ts=8 sts=0: |
| 4 | * |
| 5 | * symlink.c - operations for configfs symlinks. |
| 6 | * |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 7 | * Based on sysfs: |
| 8 | * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel |
| 9 | * |
| 10 | * configfs Copyright (C) 2005 Oracle. All rights reserved. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/fs.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/namei.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 16 | #include <linux/slab.h> |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 17 | |
| 18 | #include <linux/configfs.h> |
| 19 | #include "configfs_internal.h" |
| 20 | |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 21 | /* Protects attachments of new symlinks */ |
| 22 | DEFINE_MUTEX(configfs_symlink_mutex); |
| 23 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 24 | static int item_depth(struct config_item * item) |
| 25 | { |
| 26 | struct config_item * p = item; |
| 27 | int depth = 0; |
| 28 | do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p)); |
| 29 | return depth; |
| 30 | } |
| 31 | |
| 32 | static int item_path_length(struct config_item * item) |
| 33 | { |
| 34 | struct config_item * p = item; |
| 35 | int length = 1; |
| 36 | do { |
| 37 | length += strlen(config_item_name(p)) + 1; |
| 38 | p = p->ci_parent; |
| 39 | } while (p && !configfs_is_root(p)); |
| 40 | return length; |
| 41 | } |
| 42 | |
| 43 | static void fill_item_path(struct config_item * item, char * buffer, int length) |
| 44 | { |
| 45 | struct config_item * p; |
| 46 | |
| 47 | --length; |
| 48 | for (p = item; p && !configfs_is_root(p); p = p->ci_parent) { |
| 49 | int cur = strlen(config_item_name(p)); |
| 50 | |
| 51 | /* back up enough to print this bus id with '/' */ |
| 52 | length -= cur; |
Guenter Roeck | 1823342 | 2018-07-01 13:56:54 -0700 | [diff] [blame] | 53 | memcpy(buffer + length, config_item_name(p), cur); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 54 | *(buffer + --length) = '/'; |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | static int create_link(struct config_item *parent_item, |
Joel Becker | e7515d0 | 2006-03-10 11:42:30 -0800 | [diff] [blame] | 59 | struct config_item *item, |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 60 | struct dentry *dentry) |
| 61 | { |
| 62 | struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata; |
| 63 | struct configfs_symlink *sl; |
| 64 | int ret; |
| 65 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 66 | ret = -ENOENT; |
| 67 | if (!configfs_dirent_is_ready(target_sd)) |
| 68 | goto out; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 69 | ret = -ENOMEM; |
| 70 | sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); |
| 71 | if (sl) { |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 72 | spin_lock(&configfs_dirent_lock); |
Louis Rilling | 4768e9b | 2008-06-23 14:16:17 +0200 | [diff] [blame] | 73 | if (target_sd->s_type & CONFIGFS_USET_DROPPING) { |
| 74 | spin_unlock(&configfs_dirent_lock); |
Louis Rilling | 4768e9b | 2008-06-23 14:16:17 +0200 | [diff] [blame] | 75 | kfree(sl); |
| 76 | return -ENOENT; |
| 77 | } |
Nicholas Bellinger | ba80aa9 | 2017-06-08 04:51:54 +0000 | [diff] [blame] | 78 | sl->sl_target = config_item_get(item); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 79 | list_add(&sl->sl_list, &target_sd->s_links); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 80 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 81 | ret = configfs_create_link(sl, parent_item->ci_dentry, |
| 82 | dentry); |
| 83 | if (ret) { |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 84 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 85 | list_del_init(&sl->sl_list); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 86 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 87 | config_item_put(item); |
| 88 | kfree(sl); |
| 89 | } |
| 90 | } |
| 91 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 92 | out: |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 93 | return ret; |
| 94 | } |
| 95 | |
| 96 | |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 97 | static int get_target(const char *symname, struct path *path, |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 98 | struct config_item **target, struct super_block *sb) |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 99 | { |
| 100 | int ret; |
| 101 | |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 102 | ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 103 | if (!ret) { |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 104 | if (path->dentry->d_sb == sb) { |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 105 | *target = configfs_get_config_item(path->dentry); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 106 | if (!*target) { |
| 107 | ret = -ENOENT; |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 108 | path_put(path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 109 | } |
Al Viro | 9b6e310 | 2010-01-13 22:10:57 -0500 | [diff] [blame] | 110 | } else { |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 111 | ret = -EPERM; |
Al Viro | 9b6e310 | 2010-01-13 22:10:57 -0500 | [diff] [blame] | 112 | path_put(path); |
| 113 | } |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 114 | } |
| 115 | |
| 116 | return ret; |
| 117 | } |
| 118 | |
| 119 | |
| 120 | int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
| 121 | { |
| 122 | int ret; |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 123 | struct path path; |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 124 | struct configfs_dirent *sd; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 125 | struct config_item *parent_item; |
Subrata Modak | 3c48f23 | 2009-04-19 01:10:03 +0530 | [diff] [blame] | 126 | struct config_item *target_item = NULL; |
Bhumika Goyal | aa29358 | 2017-10-16 17:18:40 +0200 | [diff] [blame] | 127 | const struct config_item_type *type; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 128 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 129 | sd = dentry->d_parent->d_fsdata; |
| 130 | /* |
| 131 | * Fake invisibility if dir belongs to a group/default groups hierarchy |
| 132 | * being attached |
| 133 | */ |
| 134 | ret = -ENOENT; |
| 135 | if (!configfs_dirent_is_ready(sd)) |
| 136 | goto out; |
| 137 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 138 | parent_item = configfs_get_config_item(dentry->d_parent); |
| 139 | type = parent_item->ci_type; |
| 140 | |
Louis Rilling | 2a109f2 | 2008-07-04 16:56:05 +0200 | [diff] [blame] | 141 | ret = -EPERM; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 142 | if (!type || !type->ct_item_ops || |
| 143 | !type->ct_item_ops->allow_link) |
| 144 | goto out_put; |
| 145 | |
Al Viro | b7c177f | 2012-03-17 16:24:54 -0400 | [diff] [blame] | 146 | ret = get_target(symname, &path, &target_item, dentry->d_sb); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 147 | if (ret) |
| 148 | goto out_put; |
| 149 | |
| 150 | ret = type->ct_item_ops->allow_link(parent_item, target_item); |
Louis Rilling | e752065 | 2008-06-12 17:26:47 +0200 | [diff] [blame] | 151 | if (!ret) { |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 152 | mutex_lock(&configfs_symlink_mutex); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 153 | ret = create_link(parent_item, target_item, dentry); |
Louis Rilling | 9a73d78 | 2008-06-20 14:09:22 +0200 | [diff] [blame] | 154 | mutex_unlock(&configfs_symlink_mutex); |
Louis Rilling | e752065 | 2008-06-12 17:26:47 +0200 | [diff] [blame] | 155 | if (ret && type->ct_item_ops->drop_link) |
| 156 | type->ct_item_ops->drop_link(parent_item, |
| 157 | target_item); |
| 158 | } |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 159 | |
| 160 | config_item_put(target_item); |
Al Viro | 421748e | 2008-08-02 01:04:36 -0400 | [diff] [blame] | 161 | path_put(&path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 162 | |
| 163 | out_put: |
| 164 | config_item_put(parent_item); |
| 165 | |
| 166 | out: |
| 167 | return ret; |
| 168 | } |
| 169 | |
| 170 | int configfs_unlink(struct inode *dir, struct dentry *dentry) |
| 171 | { |
| 172 | struct configfs_dirent *sd = dentry->d_fsdata; |
| 173 | struct configfs_symlink *sl; |
| 174 | struct config_item *parent_item; |
Bhumika Goyal | aa29358 | 2017-10-16 17:18:40 +0200 | [diff] [blame] | 175 | const struct config_item_type *type; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 176 | int ret; |
| 177 | |
| 178 | ret = -EPERM; /* What lack-of-symlink returns */ |
| 179 | if (!(sd->s_type & CONFIGFS_ITEM_LINK)) |
| 180 | goto out; |
| 181 | |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 182 | sl = sd->s_element; |
| 183 | |
| 184 | parent_item = configfs_get_config_item(dentry->d_parent); |
| 185 | type = parent_item->ci_type; |
| 186 | |
Louis Rilling | 6f61076 | 2008-06-16 19:00:58 +0200 | [diff] [blame] | 187 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 188 | list_del_init(&sd->s_sibling); |
Louis Rilling | 6f61076 | 2008-06-16 19:00:58 +0200 | [diff] [blame] | 189 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 190 | configfs_drop_dentry(sd, dentry->d_parent); |
| 191 | dput(dentry); |
| 192 | configfs_put(sd); |
| 193 | |
| 194 | /* |
| 195 | * drop_link() must be called before |
| 196 | * list_del_init(&sl->sl_list), so that the order of |
| 197 | * drop_link(this, target) and drop_item(target) is preserved. |
| 198 | */ |
| 199 | if (type && type->ct_item_ops && |
| 200 | type->ct_item_ops->drop_link) |
| 201 | type->ct_item_ops->drop_link(parent_item, |
| 202 | sl->sl_target); |
| 203 | |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 204 | spin_lock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 205 | list_del_init(&sl->sl_list); |
Louis Rilling | 5301a77 | 2008-06-16 19:00:59 +0200 | [diff] [blame] | 206 | spin_unlock(&configfs_dirent_lock); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 207 | |
| 208 | /* Put reference from create_link() */ |
| 209 | config_item_put(sl->sl_target); |
| 210 | kfree(sl); |
| 211 | |
| 212 | config_item_put(parent_item); |
| 213 | |
| 214 | ret = 0; |
| 215 | |
| 216 | out: |
| 217 | return ret; |
| 218 | } |
| 219 | |
| 220 | static int configfs_get_target_path(struct config_item * item, struct config_item * target, |
| 221 | char *path) |
| 222 | { |
| 223 | char * s; |
| 224 | int depth, size; |
| 225 | |
| 226 | depth = item_depth(item); |
| 227 | size = item_path_length(target) + depth * 3 - 1; |
| 228 | if (size > PATH_MAX) |
| 229 | return -ENAMETOOLONG; |
| 230 | |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 231 | pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 232 | |
| 233 | for (s = path; depth--; s += 3) |
| 234 | strcpy(s,"../"); |
| 235 | |
| 236 | fill_item_path(target, path, size); |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 237 | pr_debug("%s: path = '%s'\n", __func__, path); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 238 | |
| 239 | return 0; |
| 240 | } |
| 241 | |
| 242 | static int configfs_getlink(struct dentry *dentry, char * path) |
| 243 | { |
| 244 | struct config_item *item, *target_item; |
| 245 | int error = 0; |
| 246 | |
| 247 | item = configfs_get_config_item(dentry->d_parent); |
| 248 | if (!item) |
| 249 | return -EINVAL; |
| 250 | |
| 251 | target_item = configfs_get_config_item(dentry); |
| 252 | if (!target_item) { |
| 253 | config_item_put(item); |
| 254 | return -EINVAL; |
| 255 | } |
| 256 | |
| 257 | down_read(&configfs_rename_sem); |
| 258 | error = configfs_get_target_path(item, target_item, path); |
| 259 | up_read(&configfs_rename_sem); |
| 260 | |
| 261 | config_item_put(item); |
| 262 | config_item_put(target_item); |
| 263 | return error; |
| 264 | |
| 265 | } |
| 266 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 267 | static const char *configfs_get_link(struct dentry *dentry, |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 268 | struct inode *inode, |
| 269 | struct delayed_call *done) |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 270 | { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 271 | char *body; |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 272 | int error; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 273 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 274 | if (!dentry) |
| 275 | return ERR_PTR(-ECHILD); |
| 276 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 277 | body = kzalloc(PAGE_SIZE, GFP_KERNEL); |
| 278 | if (!body) |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 279 | return ERR_PTR(-ENOMEM); |
| 280 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 281 | error = configfs_getlink(dentry, body); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 282 | if (!error) { |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 283 | set_delayed_call(done, kfree_link, body); |
| 284 | return body; |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 285 | } |
| 286 | |
Al Viro | fceef39 | 2015-12-29 15:58:39 -0500 | [diff] [blame] | 287 | kfree(body); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 288 | return ERR_PTR(error); |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 289 | } |
| 290 | |
Arjan van de Ven | 754661f | 2007-02-12 00:55:38 -0800 | [diff] [blame] | 291 | const struct inode_operations configfs_symlink_inode_operations = { |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 292 | .get_link = configfs_get_link, |
Joel Becker | 3d0f89b | 2006-01-25 13:31:07 -0800 | [diff] [blame] | 293 | .setattr = configfs_setattr, |
Joel Becker | 7063fbf | 2005-12-15 14:29:43 -0800 | [diff] [blame] | 294 | }; |
| 295 | |