Thomas Gleixner | 59bd9de | 2019-05-28 10:10:12 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * linux/fs/namespace.c |
| 4 | * |
| 5 | * (C) Copyright Al Viro 2000, 2001 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. |
| 8 | * Heavily rewritten. |
| 9 | */ |
| 10 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/syscalls.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 12 | #include <linux/export.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 13 | #include <linux/capability.h> |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 14 | #include <linux/mnt_namespace.h> |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 15 | #include <linux/user_namespace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/namei.h> |
| 17 | #include <linux/security.h> |
Ingo Molnar | 5b825c3 | 2017-02-02 17:54:15 +0100 | [diff] [blame] | 18 | #include <linux/cred.h> |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 19 | #include <linux/idr.h> |
Rob Landley | 57f150a | 2013-09-11 14:26:10 -0700 | [diff] [blame] | 20 | #include <linux/init.h> /* init_rootfs */ |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 21 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
| 22 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 23 | #include <linux/file.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 24 | #include <linux/uaccess.h> |
David Howells | 0bb80f2 | 2013-04-12 01:50:06 +0100 | [diff] [blame] | 25 | #include <linux/proc_ns.h> |
Linus Torvalds | 20b4fb4 | 2013-05-01 17:51:54 -0700 | [diff] [blame] | 26 | #include <linux/magic.h> |
Mike Rapoport | 57c8a66 | 2018-10-30 15:09:49 -0700 | [diff] [blame] | 27 | #include <linux/memblock.h> |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 28 | #include <linux/task_work.h> |
Ingo Molnar | 9164bb4 | 2017-02-04 01:20:53 +0100 | [diff] [blame] | 29 | #include <linux/sched/task.h> |
David Howells | e262e32d | 2018-11-01 23:07:23 +0000 | [diff] [blame] | 30 | #include <uapi/linux/mount.h> |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 31 | #include <linux/fs_context.h> |
Al Viro | 037f11b | 2019-06-01 18:09:44 -0400 | [diff] [blame] | 32 | #include <linux/shmem_fs.h> |
Ingo Molnar | 9164bb4 | 2017-02-04 01:20:53 +0100 | [diff] [blame] | 33 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 34 | #include "pnode.h" |
Adrian Bunk | 948730b | 2007-07-15 23:41:25 -0700 | [diff] [blame] | 35 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 37 | /* Maximum number of mounts in a mount namespace */ |
| 38 | unsigned int sysctl_mount_max __read_mostly = 100000; |
| 39 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 40 | static unsigned int m_hash_mask __read_mostly; |
| 41 | static unsigned int m_hash_shift __read_mostly; |
| 42 | static unsigned int mp_hash_mask __read_mostly; |
| 43 | static unsigned int mp_hash_shift __read_mostly; |
| 44 | |
| 45 | static __initdata unsigned long mhash_entries; |
| 46 | static int __init set_mhash_entries(char *str) |
| 47 | { |
| 48 | if (!str) |
| 49 | return 0; |
| 50 | mhash_entries = simple_strtoul(str, &str, 0); |
| 51 | return 1; |
| 52 | } |
| 53 | __setup("mhash_entries=", set_mhash_entries); |
| 54 | |
| 55 | static __initdata unsigned long mphash_entries; |
| 56 | static int __init set_mphash_entries(char *str) |
| 57 | { |
| 58 | if (!str) |
| 59 | return 0; |
| 60 | mphash_entries = simple_strtoul(str, &str, 0); |
| 61 | return 1; |
| 62 | } |
| 63 | __setup("mphash_entries=", set_mphash_entries); |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 64 | |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 65 | static u64 event; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 66 | static DEFINE_IDA(mnt_id_ida); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 67 | static DEFINE_IDA(mnt_group_ida); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 69 | static struct hlist_head *mount_hashtable __read_mostly; |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 70 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 71 | static struct kmem_cache *mnt_cache __read_mostly; |
Al Viro | 59aa0da | 2013-09-16 21:34:53 -0400 | [diff] [blame] | 72 | static DECLARE_RWSEM(namespace_sem); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 73 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
| 74 | static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 76 | /* /sys/fs */ |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 77 | struct kobject *fs_kobj; |
| 78 | EXPORT_SYMBOL_GPL(fs_kobj); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 79 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 80 | /* |
| 81 | * vfsmount lock may be taken for read to prevent changes to the |
| 82 | * vfsmount hash, ie. during mountpoint lookups or walking back |
| 83 | * up the tree. |
| 84 | * |
| 85 | * It should be taken for write in all cases where the vfsmount |
| 86 | * tree or hash is modified or when a vfsmount structure is modified. |
| 87 | */ |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 88 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 89 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 90 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 91 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 92 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 93 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 94 | tmp = tmp + (tmp >> m_hash_shift); |
| 95 | return &mount_hashtable[tmp & m_hash_mask]; |
| 96 | } |
| 97 | |
| 98 | static inline struct hlist_head *mp_hash(struct dentry *dentry) |
| 99 | { |
| 100 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); |
| 101 | tmp = tmp + (tmp >> mp_hash_shift); |
| 102 | return &mountpoint_hashtable[tmp & mp_hash_mask]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | } |
| 104 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 105 | static int mnt_alloc_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 106 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 107 | int res = ida_alloc(&mnt_id_ida, GFP_KERNEL); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 108 | |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 109 | if (res < 0) |
| 110 | return res; |
| 111 | mnt->mnt_id = res; |
| 112 | return 0; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 113 | } |
| 114 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 115 | static void mnt_free_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 116 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 117 | ida_free(&mnt_id_ida, mnt->mnt_id); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 118 | } |
| 119 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 120 | /* |
| 121 | * Allocate a new peer group ID |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 122 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 123 | static int mnt_alloc_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 124 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 125 | int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 126 | |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 127 | if (res < 0) |
| 128 | return res; |
| 129 | mnt->mnt_group_id = res; |
| 130 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 131 | } |
| 132 | |
| 133 | /* |
| 134 | * Release a peer group ID |
| 135 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 136 | void mnt_release_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 137 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 138 | ida_free(&mnt_group_ida, mnt->mnt_group_id); |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 139 | mnt->mnt_group_id = 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 140 | } |
| 141 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 142 | /* |
| 143 | * vfsmount lock must be held for read |
| 144 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 145 | static inline void mnt_add_count(struct mount *mnt, int n) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 146 | { |
| 147 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 148 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 149 | #else |
| 150 | preempt_disable(); |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 151 | mnt->mnt_count += n; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 152 | preempt_enable(); |
| 153 | #endif |
| 154 | } |
| 155 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 156 | /* |
| 157 | * vfsmount lock must be held for write |
| 158 | */ |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 159 | int mnt_get_count(struct mount *mnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 160 | { |
| 161 | #ifdef CONFIG_SMP |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 162 | int count = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 163 | int cpu; |
| 164 | |
| 165 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 166 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 167 | } |
| 168 | |
| 169 | return count; |
| 170 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 171 | return mnt->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 172 | #endif |
| 173 | } |
| 174 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 175 | static struct mount *alloc_vfsmnt(const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 176 | { |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 177 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
| 178 | if (mnt) { |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 179 | int err; |
| 180 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 181 | err = mnt_alloc_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 182 | if (err) |
| 183 | goto out_free_cache; |
| 184 | |
| 185 | if (name) { |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 186 | mnt->mnt_devname = kstrdup_const(name, GFP_KERNEL); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 187 | if (!mnt->mnt_devname) |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 188 | goto out_free_id; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 189 | } |
| 190 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 191 | #ifdef CONFIG_SMP |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 192 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
| 193 | if (!mnt->mnt_pcp) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 194 | goto out_free_devname; |
| 195 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 196 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 197 | #else |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 198 | mnt->mnt_count = 1; |
| 199 | mnt->mnt_writers = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 200 | #endif |
| 201 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 202 | INIT_HLIST_NODE(&mnt->mnt_hash); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 203 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 204 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 205 | INIT_LIST_HEAD(&mnt->mnt_list); |
| 206 | INIT_LIST_HEAD(&mnt->mnt_expire); |
| 207 | INIT_LIST_HEAD(&mnt->mnt_share); |
| 208 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 209 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 210 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
Eric W. Biederman | 99b19d1 | 2016-10-24 16:16:13 -0500 | [diff] [blame] | 211 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 212 | INIT_HLIST_HEAD(&mnt->mnt_stuck_children); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | } |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 214 | return mnt; |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 215 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 216 | #ifdef CONFIG_SMP |
| 217 | out_free_devname: |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 218 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 219 | #endif |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 220 | out_free_id: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 221 | mnt_free_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 222 | out_free_cache: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 223 | kmem_cache_free(mnt_cache, mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 224 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | } |
| 226 | |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 227 | /* |
| 228 | * Most r/o checks on a fs are for operations that take |
| 229 | * discrete amounts of time, like a write() or unlink(). |
| 230 | * We must keep track of when those operations start |
| 231 | * (for permission checks) and when they end, so that |
| 232 | * we can determine when writes are able to occur to |
| 233 | * a filesystem. |
| 234 | */ |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 235 | /* |
| 236 | * __mnt_is_readonly: check whether a mount is read-only |
| 237 | * @mnt: the mount to check for its write status |
| 238 | * |
| 239 | * This shouldn't be used directly ouside of the VFS. |
| 240 | * It does not guarantee that the filesystem will stay |
| 241 | * r/w, just that it is right *now*. This can not and |
| 242 | * should not be used in place of IS_RDONLY(inode). |
| 243 | * mnt_want/drop_write() will _keep_ the filesystem |
| 244 | * r/w. |
| 245 | */ |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 246 | bool __mnt_is_readonly(struct vfsmount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 247 | { |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 248 | return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 249 | } |
| 250 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 251 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 252 | static inline void mnt_inc_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 253 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 254 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 255 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 256 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 257 | mnt->mnt_writers++; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 258 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 259 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 260 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 261 | static inline void mnt_dec_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 262 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 263 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 264 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 265 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 266 | mnt->mnt_writers--; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 267 | #endif |
| 268 | } |
| 269 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 270 | static unsigned int mnt_get_writers(struct mount *mnt) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 271 | { |
| 272 | #ifdef CONFIG_SMP |
| 273 | unsigned int count = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 274 | int cpu; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 275 | |
| 276 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 277 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 278 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 279 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 280 | return count; |
| 281 | #else |
| 282 | return mnt->mnt_writers; |
| 283 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 284 | } |
| 285 | |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 286 | static int mnt_is_readonly(struct vfsmount *mnt) |
| 287 | { |
| 288 | if (mnt->mnt_sb->s_readonly_remount) |
| 289 | return 1; |
| 290 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ |
| 291 | smp_rmb(); |
| 292 | return __mnt_is_readonly(mnt); |
| 293 | } |
| 294 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 295 | /* |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 296 | * Most r/o & frozen checks on a fs are for operations that take discrete |
| 297 | * amounts of time, like a write() or unlink(). We must keep track of when |
| 298 | * those operations start (for permission checks) and when they end, so that we |
| 299 | * can determine when writes are able to occur to a filesystem. |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 300 | */ |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 301 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 302 | * __mnt_want_write - get write access to a mount without freeze protection |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 303 | * @m: the mount on which to take a write |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 304 | * |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 305 | * This tells the low-level filesystem that a write is about to be performed to |
| 306 | * it, and makes sure that writes are allowed (mnt it read-write) before |
| 307 | * returning success. This operation does not protect against filesystem being |
| 308 | * frozen. When the write operation is finished, __mnt_drop_write() must be |
| 309 | * called. This is effectively a refcount. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 310 | */ |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 311 | int __mnt_want_write(struct vfsmount *m) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 312 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 313 | struct mount *mnt = real_mount(m); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 314 | int ret = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 315 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 316 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 317 | mnt_inc_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 318 | /* |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 319 | * The store to mnt_inc_writers must be visible before we pass |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 320 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 321 | * incremented count after it has set MNT_WRITE_HOLD. |
| 322 | */ |
| 323 | smp_mb(); |
Mark Rutland | 6aa7de0 | 2017-10-23 14:07:29 -0700 | [diff] [blame] | 324 | while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 325 | cpu_relax(); |
| 326 | /* |
| 327 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will |
| 328 | * be set to match its requirements. So we must not load that until |
| 329 | * MNT_WRITE_HOLD is cleared. |
| 330 | */ |
| 331 | smp_rmb(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 332 | if (mnt_is_readonly(m)) { |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 333 | mnt_dec_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 334 | ret = -EROFS; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 335 | } |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 336 | preempt_enable(); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 337 | |
| 338 | return ret; |
| 339 | } |
| 340 | |
| 341 | /** |
| 342 | * mnt_want_write - get write access to a mount |
| 343 | * @m: the mount on which to take a write |
| 344 | * |
| 345 | * This tells the low-level filesystem that a write is about to be performed to |
| 346 | * it, and makes sure that writes are allowed (mount is read-write, filesystem |
| 347 | * is not frozen) before returning success. When the write operation is |
| 348 | * finished, mnt_drop_write() must be called. This is effectively a refcount. |
| 349 | */ |
| 350 | int mnt_want_write(struct vfsmount *m) |
| 351 | { |
| 352 | int ret; |
| 353 | |
| 354 | sb_start_write(m->mnt_sb); |
| 355 | ret = __mnt_want_write(m); |
| 356 | if (ret) |
| 357 | sb_end_write(m->mnt_sb); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 358 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 359 | } |
| 360 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 361 | |
| 362 | /** |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 363 | * mnt_clone_write - get write access to a mount |
| 364 | * @mnt: the mount on which to take a write |
| 365 | * |
| 366 | * This is effectively like mnt_want_write, except |
| 367 | * it must only be used to take an extra write reference |
| 368 | * on a mountpoint that we already know has a write reference |
| 369 | * on it. This allows some optimisation. |
| 370 | * |
| 371 | * After finished, mnt_drop_write must be called as usual to |
| 372 | * drop the reference. |
| 373 | */ |
| 374 | int mnt_clone_write(struct vfsmount *mnt) |
| 375 | { |
| 376 | /* superblock may be r/o */ |
| 377 | if (__mnt_is_readonly(mnt)) |
| 378 | return -EROFS; |
| 379 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 380 | mnt_inc_writers(real_mount(mnt)); |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 381 | preempt_enable(); |
| 382 | return 0; |
| 383 | } |
| 384 | EXPORT_SYMBOL_GPL(mnt_clone_write); |
| 385 | |
| 386 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 387 | * __mnt_want_write_file - get write access to a file's mount |
| 388 | * @file: the file who's mount on which to take a write |
| 389 | * |
| 390 | * This is like __mnt_want_write, but it takes a file and can |
| 391 | * do some optimisations if the file is open for write already |
| 392 | */ |
| 393 | int __mnt_want_write_file(struct file *file) |
| 394 | { |
Al Viro | 83f936c | 2014-03-14 12:02:47 -0400 | [diff] [blame] | 395 | if (!(file->f_mode & FMODE_WRITER)) |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 396 | return __mnt_want_write(file->f_path.mnt); |
| 397 | else |
| 398 | return mnt_clone_write(file->f_path.mnt); |
| 399 | } |
| 400 | |
| 401 | /** |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 402 | * mnt_want_write_file - get write access to a file's mount |
| 403 | * @file: the file who's mount on which to take a write |
| 404 | * |
| 405 | * This is like mnt_want_write, but it takes a file and can |
| 406 | * do some optimisations if the file is open for write already |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 407 | */ |
| 408 | int mnt_want_write_file(struct file *file) |
| 409 | { |
| 410 | int ret; |
| 411 | |
Miklos Szeredi | a6795a5 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 412 | sb_start_write(file_inode(file)->i_sb); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 413 | ret = __mnt_want_write_file(file); |
| 414 | if (ret) |
Miklos Szeredi | a6795a5 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 415 | sb_end_write(file_inode(file)->i_sb); |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 416 | return ret; |
| 417 | } |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 418 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
| 419 | |
| 420 | /** |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 421 | * __mnt_drop_write - give up write access to a mount |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 422 | * @mnt: the mount on which to give up write access |
| 423 | * |
| 424 | * Tells the low-level filesystem that we are done |
| 425 | * performing writes to it. Must be matched with |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 426 | * __mnt_want_write() call above. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 427 | */ |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 428 | void __mnt_drop_write(struct vfsmount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 429 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 430 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 431 | mnt_dec_writers(real_mount(mnt)); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 432 | preempt_enable(); |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 433 | } |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 434 | |
| 435 | /** |
| 436 | * mnt_drop_write - give up write access to a mount |
| 437 | * @mnt: the mount on which to give up write access |
| 438 | * |
| 439 | * Tells the low-level filesystem that we are done performing writes to it and |
| 440 | * also allows filesystem to be frozen again. Must be matched with |
| 441 | * mnt_want_write() call above. |
| 442 | */ |
| 443 | void mnt_drop_write(struct vfsmount *mnt) |
| 444 | { |
| 445 | __mnt_drop_write(mnt); |
| 446 | sb_end_write(mnt->mnt_sb); |
| 447 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 448 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 449 | |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 450 | void __mnt_drop_write_file(struct file *file) |
| 451 | { |
| 452 | __mnt_drop_write(file->f_path.mnt); |
| 453 | } |
| 454 | |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 455 | void mnt_drop_write_file(struct file *file) |
| 456 | { |
Miklos Szeredi | a6795a5 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 457 | __mnt_drop_write_file(file); |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 458 | sb_end_write(file_inode(file)->i_sb); |
| 459 | } |
Al Viro | 2a79f17 | 2011-12-09 08:06:57 -0500 | [diff] [blame] | 460 | EXPORT_SYMBOL(mnt_drop_write_file); |
| 461 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 462 | static int mnt_make_readonly(struct mount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 463 | { |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 464 | int ret = 0; |
| 465 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 466 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 467 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 468 | /* |
| 469 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 470 | * should be visible before we do. |
| 471 | */ |
| 472 | smp_mb(); |
| 473 | |
| 474 | /* |
| 475 | * With writers on hold, if this value is zero, then there are |
| 476 | * definitely no active writers (although held writers may subsequently |
| 477 | * increment the count, they'll have to wait, and decrement it after |
| 478 | * seeing MNT_READONLY). |
| 479 | * |
| 480 | * It is OK to have counter incremented on one CPU and decremented on |
| 481 | * another: the sum will add up correctly. The danger would be when we |
| 482 | * sum up each counter, if we read a counter before it is incremented, |
| 483 | * but then read another CPU's count which it has been subsequently |
| 484 | * decremented from -- we would see more decrements than we should. |
| 485 | * MNT_WRITE_HOLD protects against this scenario, because |
| 486 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 487 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 488 | * we're counting up here. |
| 489 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 490 | if (mnt_get_writers(mnt) > 0) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 491 | ret = -EBUSY; |
| 492 | else |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 493 | mnt->mnt.mnt_flags |= MNT_READONLY; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 494 | /* |
| 495 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 496 | * that become unheld will see MNT_READONLY. |
| 497 | */ |
| 498 | smp_wmb(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 499 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 500 | unlock_mount_hash(); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 501 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 502 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 503 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 504 | static int __mnt_unmake_readonly(struct mount *mnt) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 505 | { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 506 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 507 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 508 | unlock_mount_hash(); |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 509 | return 0; |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 510 | } |
| 511 | |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 512 | int sb_prepare_remount_readonly(struct super_block *sb) |
| 513 | { |
| 514 | struct mount *mnt; |
| 515 | int err = 0; |
| 516 | |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 517 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
| 518 | if (atomic_long_read(&sb->s_remove_count)) |
| 519 | return -EBUSY; |
| 520 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 521 | lock_mount_hash(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 522 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 523 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { |
| 524 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
| 525 | smp_mb(); |
| 526 | if (mnt_get_writers(mnt) > 0) { |
| 527 | err = -EBUSY; |
| 528 | break; |
| 529 | } |
| 530 | } |
| 531 | } |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 532 | if (!err && atomic_long_read(&sb->s_remove_count)) |
| 533 | err = -EBUSY; |
| 534 | |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 535 | if (!err) { |
| 536 | sb->s_readonly_remount = 1; |
| 537 | smp_wmb(); |
| 538 | } |
| 539 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 540 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
| 541 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
| 542 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 543 | unlock_mount_hash(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 544 | |
| 545 | return err; |
| 546 | } |
| 547 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 548 | static void free_vfsmnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | { |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 550 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 551 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 552 | free_percpu(mnt->mnt_pcp); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 553 | #endif |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 554 | kmem_cache_free(mnt_cache, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 555 | } |
| 556 | |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 557 | static void delayed_free_vfsmnt(struct rcu_head *head) |
| 558 | { |
| 559 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); |
| 560 | } |
| 561 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 562 | /* call under rcu_read_lock */ |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 563 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 564 | { |
| 565 | struct mount *mnt; |
| 566 | if (read_seqretry(&mount_lock, seq)) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 567 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 568 | if (bastard == NULL) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 569 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 570 | mnt = real_mount(bastard); |
| 571 | mnt_add_count(mnt, 1); |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 572 | smp_mb(); // see mntput_no_expire() |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 573 | if (likely(!read_seqretry(&mount_lock, seq))) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 574 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 575 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
| 576 | mnt_add_count(mnt, -1); |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 577 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 578 | } |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 579 | lock_mount_hash(); |
| 580 | if (unlikely(bastard->mnt_flags & MNT_DOOMED)) { |
| 581 | mnt_add_count(mnt, -1); |
| 582 | unlock_mount_hash(); |
| 583 | return 1; |
| 584 | } |
| 585 | unlock_mount_hash(); |
| 586 | /* caller will mntput() */ |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 587 | return -1; |
| 588 | } |
| 589 | |
| 590 | /* call under rcu_read_lock */ |
| 591 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
| 592 | { |
| 593 | int res = __legitimize_mnt(bastard, seq); |
| 594 | if (likely(!res)) |
| 595 | return true; |
| 596 | if (unlikely(res < 0)) { |
| 597 | rcu_read_unlock(); |
| 598 | mntput(bastard); |
| 599 | rcu_read_lock(); |
| 600 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 601 | return false; |
| 602 | } |
| 603 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 604 | /* |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 605 | * find the first mount at @dentry on vfsmount @mnt. |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 606 | * call under rcu_read_lock() |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 607 | */ |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 608 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 609 | { |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 610 | struct hlist_head *head = m_hash(mnt, dentry); |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 611 | struct mount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 612 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 613 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 614 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
| 615 | return p; |
| 616 | return NULL; |
| 617 | } |
| 618 | |
| 619 | /* |
David Howells | f015f126 | 2012-06-25 12:55:28 +0100 | [diff] [blame] | 620 | * lookup_mnt - Return the first child mount mounted at path |
| 621 | * |
| 622 | * "First" means first mounted chronologically. If you create the |
| 623 | * following mounts: |
| 624 | * |
| 625 | * mount /dev/sda1 /mnt |
| 626 | * mount /dev/sda2 /mnt |
| 627 | * mount /dev/sda3 /mnt |
| 628 | * |
| 629 | * Then lookup_mnt() on the base /mnt dentry in the root mount will |
| 630 | * return successively the root dentry and vfsmount of /dev/sda1, then |
| 631 | * /dev/sda2, then /dev/sda3, then NULL. |
| 632 | * |
| 633 | * lookup_mnt takes a reference to the found vfsmount. |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 634 | */ |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 635 | struct vfsmount *lookup_mnt(const struct path *path) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 636 | { |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 637 | struct mount *child_mnt; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 638 | struct vfsmount *m; |
| 639 | unsigned seq; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 640 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 641 | rcu_read_lock(); |
| 642 | do { |
| 643 | seq = read_seqbegin(&mount_lock); |
| 644 | child_mnt = __lookup_mnt(path->mnt, path->dentry); |
| 645 | m = child_mnt ? &child_mnt->mnt : NULL; |
| 646 | } while (!legitimize_mnt(m, seq)); |
| 647 | rcu_read_unlock(); |
| 648 | return m; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 649 | } |
| 650 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 651 | static inline void lock_ns_list(struct mnt_namespace *ns) |
| 652 | { |
| 653 | spin_lock(&ns->ns_lock); |
| 654 | } |
| 655 | |
| 656 | static inline void unlock_ns_list(struct mnt_namespace *ns) |
| 657 | { |
| 658 | spin_unlock(&ns->ns_lock); |
| 659 | } |
| 660 | |
| 661 | static inline bool mnt_is_cursor(struct mount *mnt) |
| 662 | { |
| 663 | return mnt->mnt.mnt_flags & MNT_CURSOR; |
| 664 | } |
| 665 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 666 | /* |
| 667 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the |
| 668 | * current mount namespace. |
| 669 | * |
| 670 | * The common case is dentries are not mountpoints at all and that |
| 671 | * test is handled inline. For the slow case when we are actually |
| 672 | * dealing with a mountpoint of some kind, walk through all of the |
| 673 | * mounts in the current mount namespace and test to see if the dentry |
| 674 | * is a mountpoint. |
| 675 | * |
| 676 | * The mount_hashtable is not usable in the context because we |
| 677 | * need to identify all mounts that may be in the current mount |
| 678 | * namespace not just a mount that happens to have some specified |
| 679 | * parent mount. |
| 680 | */ |
| 681 | bool __is_local_mountpoint(struct dentry *dentry) |
| 682 | { |
| 683 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 684 | struct mount *mnt; |
| 685 | bool is_covered = false; |
| 686 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 687 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 688 | lock_ns_list(ns); |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 689 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 690 | if (mnt_is_cursor(mnt)) |
| 691 | continue; |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 692 | is_covered = (mnt->mnt_mountpoint == dentry); |
| 693 | if (is_covered) |
| 694 | break; |
| 695 | } |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 696 | unlock_ns_list(ns); |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 697 | up_read(&namespace_sem); |
Nikolay Borisov | 5ad05cc | 2020-03-04 18:12:45 +0200 | [diff] [blame] | 698 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 699 | return is_covered; |
| 700 | } |
| 701 | |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 702 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 703 | { |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 704 | struct hlist_head *chain = mp_hash(dentry); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 705 | struct mountpoint *mp; |
| 706 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 707 | hlist_for_each_entry(mp, chain, m_hash) { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 708 | if (mp->m_dentry == dentry) { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 709 | mp->m_count++; |
| 710 | return mp; |
| 711 | } |
| 712 | } |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 713 | return NULL; |
| 714 | } |
| 715 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 716 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 717 | { |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 718 | struct mountpoint *mp, *new = NULL; |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 719 | int ret; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 720 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 721 | if (d_mountpoint(dentry)) { |
Benjamin Coddington | 1e9c75f | 2018-10-03 10:18:33 -0400 | [diff] [blame] | 722 | /* might be worth a WARN_ON() */ |
| 723 | if (d_unlinked(dentry)) |
| 724 | return ERR_PTR(-ENOENT); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 725 | mountpoint: |
| 726 | read_seqlock_excl(&mount_lock); |
| 727 | mp = lookup_mountpoint(dentry); |
| 728 | read_sequnlock_excl(&mount_lock); |
| 729 | if (mp) |
| 730 | goto done; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 731 | } |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 732 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 733 | if (!new) |
| 734 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); |
| 735 | if (!new) |
| 736 | return ERR_PTR(-ENOMEM); |
| 737 | |
| 738 | |
| 739 | /* Exactly one processes may set d_mounted */ |
| 740 | ret = d_set_mounted(dentry); |
| 741 | |
| 742 | /* Someone else set d_mounted? */ |
| 743 | if (ret == -EBUSY) |
| 744 | goto mountpoint; |
| 745 | |
| 746 | /* The dentry is not available as a mountpoint? */ |
| 747 | mp = ERR_PTR(ret); |
| 748 | if (ret) |
| 749 | goto done; |
| 750 | |
| 751 | /* Add the new mountpoint to the hash table */ |
| 752 | read_seqlock_excl(&mount_lock); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 753 | new->m_dentry = dget(dentry); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 754 | new->m_count = 1; |
| 755 | hlist_add_head(&new->m_hash, mp_hash(dentry)); |
| 756 | INIT_HLIST_HEAD(&new->m_list); |
| 757 | read_sequnlock_excl(&mount_lock); |
| 758 | |
| 759 | mp = new; |
| 760 | new = NULL; |
| 761 | done: |
| 762 | kfree(new); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 763 | return mp; |
| 764 | } |
| 765 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 766 | /* |
| 767 | * vfsmount lock must be held. Additionally, the caller is responsible |
| 768 | * for serializing calls for given disposal list. |
| 769 | */ |
| 770 | static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 771 | { |
| 772 | if (!--mp->m_count) { |
| 773 | struct dentry *dentry = mp->m_dentry; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 774 | BUG_ON(!hlist_empty(&mp->m_list)); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 775 | spin_lock(&dentry->d_lock); |
| 776 | dentry->d_flags &= ~DCACHE_MOUNTED; |
| 777 | spin_unlock(&dentry->d_lock); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 778 | dput_to_list(dentry, list); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 779 | hlist_del(&mp->m_hash); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 780 | kfree(mp); |
| 781 | } |
| 782 | } |
| 783 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 784 | /* called with namespace_lock and vfsmount lock */ |
| 785 | static void put_mountpoint(struct mountpoint *mp) |
| 786 | { |
| 787 | __put_mountpoint(mp, &ex_mountpoints); |
| 788 | } |
| 789 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 790 | static inline int check_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 791 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 792 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 793 | } |
| 794 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 795 | /* |
| 796 | * vfsmount lock must be held for write |
| 797 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 798 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 799 | { |
| 800 | if (ns) { |
| 801 | ns->event = ++event; |
| 802 | wake_up_interruptible(&ns->poll); |
| 803 | } |
| 804 | } |
| 805 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 806 | /* |
| 807 | * vfsmount lock must be held for write |
| 808 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 809 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 810 | { |
| 811 | if (ns && ns->event != event) { |
| 812 | ns->event = event; |
| 813 | wake_up_interruptible(&ns->poll); |
| 814 | } |
| 815 | } |
| 816 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 817 | /* |
| 818 | * vfsmount lock must be held for write |
| 819 | */ |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 820 | static struct mountpoint *unhash_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 821 | { |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 822 | struct mountpoint *mp; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 823 | mnt->mnt_parent = mnt; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 824 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 825 | list_del_init(&mnt->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 826 | hlist_del_init_rcu(&mnt->mnt_hash); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 827 | hlist_del_init(&mnt->mnt_mp_list); |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 828 | mp = mnt->mnt_mp; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 829 | mnt->mnt_mp = NULL; |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 830 | return mp; |
Eric W. Biederman | 7bdb11de | 2014-12-29 13:03:41 -0600 | [diff] [blame] | 831 | } |
| 832 | |
| 833 | /* |
| 834 | * vfsmount lock must be held for write |
| 835 | */ |
Eric W. Biederman | 6a46c57 | 2015-01-15 22:58:33 -0600 | [diff] [blame] | 836 | static void umount_mnt(struct mount *mnt) |
| 837 | { |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 838 | put_mountpoint(unhash_mnt(mnt)); |
Eric W. Biederman | 6a46c57 | 2015-01-15 22:58:33 -0600 | [diff] [blame] | 839 | } |
| 840 | |
| 841 | /* |
| 842 | * vfsmount lock must be held for write |
| 843 | */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 844 | void mnt_set_mountpoint(struct mount *mnt, |
| 845 | struct mountpoint *mp, |
Al Viro | 44d964d6 | 2011-11-24 21:28:22 -0500 | [diff] [blame] | 846 | struct mount *child_mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 847 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 848 | mp->m_count++; |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 849 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 850 | child_mnt->mnt_mountpoint = mp->m_dentry; |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 851 | child_mnt->mnt_parent = mnt; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 852 | child_mnt->mnt_mp = mp; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 853 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 854 | } |
| 855 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 856 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
| 857 | { |
| 858 | hlist_add_head_rcu(&mnt->mnt_hash, |
| 859 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); |
| 860 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 861 | } |
| 862 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 863 | /* |
| 864 | * vfsmount lock must be held for write |
| 865 | */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 866 | static void attach_mnt(struct mount *mnt, |
| 867 | struct mount *parent, |
| 868 | struct mountpoint *mp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 869 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 870 | mnt_set_mountpoint(parent, mp, mnt); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 871 | __attach_mnt(mnt, parent); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 872 | } |
| 873 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 874 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 875 | { |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 876 | struct mountpoint *old_mp = mnt->mnt_mp; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 877 | struct mount *old_parent = mnt->mnt_parent; |
| 878 | |
| 879 | list_del_init(&mnt->mnt_child); |
| 880 | hlist_del_init(&mnt->mnt_mp_list); |
| 881 | hlist_del_init_rcu(&mnt->mnt_hash); |
| 882 | |
| 883 | attach_mnt(mnt, parent, mp); |
| 884 | |
| 885 | put_mountpoint(old_mp); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 886 | mnt_add_count(old_parent, -1); |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 887 | } |
| 888 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 889 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 890 | * vfsmount lock must be held for write |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 891 | */ |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 892 | static void commit_tree(struct mount *mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 893 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 894 | struct mount *parent = mnt->mnt_parent; |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 895 | struct mount *m; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 896 | LIST_HEAD(head); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 897 | struct mnt_namespace *n = parent->mnt_ns; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 898 | |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 899 | BUG_ON(parent == mnt); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 900 | |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 901 | list_add_tail(&head, &mnt->mnt_list); |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 902 | list_for_each_entry(m, &head, mnt_list) |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 903 | m->mnt_ns = n; |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 904 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 905 | list_splice(&head, n->list.prev); |
| 906 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 907 | n->mounts += n->pending_mounts; |
| 908 | n->pending_mounts = 0; |
| 909 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 910 | __attach_mnt(mnt, parent); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 911 | touch_mnt_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 912 | } |
| 913 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 914 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 915 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 916 | struct list_head *next = p->mnt_mounts.next; |
| 917 | if (next == &p->mnt_mounts) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 918 | while (1) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 919 | if (p == root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 920 | return NULL; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 921 | next = p->mnt_child.next; |
| 922 | if (next != &p->mnt_parent->mnt_mounts) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 923 | break; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 924 | p = p->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 925 | } |
| 926 | } |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 927 | return list_entry(next, struct mount, mnt_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 928 | } |
| 929 | |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 930 | static struct mount *skip_mnt_tree(struct mount *p) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 931 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 932 | struct list_head *prev = p->mnt_mounts.prev; |
| 933 | while (prev != &p->mnt_mounts) { |
| 934 | p = list_entry(prev, struct mount, mnt_child); |
| 935 | prev = p->mnt_mounts.prev; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 936 | } |
| 937 | return p; |
| 938 | } |
| 939 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 940 | /** |
| 941 | * vfs_create_mount - Create a mount for a configured superblock |
| 942 | * @fc: The configuration context with the superblock attached |
| 943 | * |
| 944 | * Create a mount to an already configured superblock. If necessary, the |
| 945 | * caller should invoke vfs_get_tree() before calling this. |
| 946 | * |
| 947 | * Note that this does not attach the mount to anything. |
| 948 | */ |
| 949 | struct vfsmount *vfs_create_mount(struct fs_context *fc) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 950 | { |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 951 | struct mount *mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 952 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 953 | if (!fc->root) |
| 954 | return ERR_PTR(-EINVAL); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 955 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 956 | mnt = alloc_vfsmnt(fc->source ?: "none"); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 957 | if (!mnt) |
| 958 | return ERR_PTR(-ENOMEM); |
| 959 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 960 | if (fc->sb_flags & SB_KERNMOUNT) |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 961 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 962 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 963 | atomic_inc(&fc->root->d_sb->s_active); |
| 964 | mnt->mnt.mnt_sb = fc->root->d_sb; |
| 965 | mnt->mnt.mnt_root = dget(fc->root); |
| 966 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 967 | mnt->mnt_parent = mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 968 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 969 | lock_mount_hash(); |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 970 | list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 971 | unlock_mount_hash(); |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 972 | return &mnt->mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 973 | } |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 974 | EXPORT_SYMBOL(vfs_create_mount); |
| 975 | |
| 976 | struct vfsmount *fc_mount(struct fs_context *fc) |
| 977 | { |
| 978 | int err = vfs_get_tree(fc); |
| 979 | if (!err) { |
| 980 | up_write(&fc->root->d_sb->s_umount); |
| 981 | return vfs_create_mount(fc); |
| 982 | } |
| 983 | return ERR_PTR(err); |
| 984 | } |
| 985 | EXPORT_SYMBOL(fc_mount); |
| 986 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 987 | struct vfsmount *vfs_kern_mount(struct file_system_type *type, |
| 988 | int flags, const char *name, |
| 989 | void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 990 | { |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 991 | struct fs_context *fc; |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 992 | struct vfsmount *mnt; |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 993 | int ret = 0; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 994 | |
| 995 | if (!type) |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 996 | return ERR_PTR(-EINVAL); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 997 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 998 | fc = fs_context_for_mount(type, flags); |
| 999 | if (IS_ERR(fc)) |
| 1000 | return ERR_CAST(fc); |
| 1001 | |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 1002 | if (name) |
| 1003 | ret = vfs_parse_fs_string(fc, "source", |
| 1004 | name, strlen(name)); |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1005 | if (!ret) |
| 1006 | ret = parse_monolithic_mount_data(fc, data); |
| 1007 | if (!ret) |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1008 | mnt = fc_mount(fc); |
| 1009 | else |
| 1010 | mnt = ERR_PTR(ret); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1011 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1012 | put_fs_context(fc); |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1013 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1014 | } |
| 1015 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
| 1016 | |
Eric W. Biederman | 93faccbb | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 1017 | struct vfsmount * |
| 1018 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, |
| 1019 | const char *name, void *data) |
| 1020 | { |
| 1021 | /* Until it is worked out how to pass the user namespace |
| 1022 | * through from the parent mount to the submount don't support |
| 1023 | * unprivileged mounts with submounts. |
| 1024 | */ |
| 1025 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) |
| 1026 | return ERR_PTR(-EPERM); |
| 1027 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 1028 | return vfs_kern_mount(type, SB_SUBMOUNT, name, data); |
Eric W. Biederman | 93faccbb | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 1029 | } |
| 1030 | EXPORT_SYMBOL_GPL(vfs_submount); |
| 1031 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1032 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1033 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1034 | { |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1035 | struct super_block *sb = old->mnt.mnt_sb; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1036 | struct mount *mnt; |
| 1037 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1038 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1039 | mnt = alloc_vfsmnt(old->mnt_devname); |
| 1040 | if (!mnt) |
| 1041 | return ERR_PTR(-ENOMEM); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1042 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1043 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1044 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 1045 | else |
| 1046 | mnt->mnt_group_id = old->mnt_group_id; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1047 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1048 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 1049 | err = mnt_alloc_group_id(mnt); |
| 1050 | if (err) |
| 1051 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1052 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1053 | |
Al Viro | 16a34ad | 2018-04-19 22:03:08 -0400 | [diff] [blame] | 1054 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
| 1055 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 1056 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1057 | atomic_inc(&sb->s_active); |
| 1058 | mnt->mnt.mnt_sb = sb; |
| 1059 | mnt->mnt.mnt_root = dget(root); |
| 1060 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 1061 | mnt->mnt_parent = mnt; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1062 | lock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1063 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1064 | unlock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1065 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1066 | if ((flag & CL_SLAVE) || |
| 1067 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1068 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 1069 | mnt->mnt_master = old; |
| 1070 | CLEAR_MNT_SHARED(mnt); |
| 1071 | } else if (!(flag & CL_PRIVATE)) { |
| 1072 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
| 1073 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 1074 | if (IS_MNT_SLAVE(old)) |
| 1075 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 1076 | mnt->mnt_master = old->mnt_master; |
Al Viro | 5235d44 | 2016-11-20 19:33:09 -0500 | [diff] [blame] | 1077 | } else { |
| 1078 | CLEAR_MNT_SHARED(mnt); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1079 | } |
| 1080 | if (flag & CL_MAKE_SHARED) |
| 1081 | set_mnt_shared(mnt); |
| 1082 | |
| 1083 | /* stick the duplicate mount on the same expiry list |
| 1084 | * as the original if that was on one */ |
| 1085 | if (flag & CL_EXPIRE) { |
| 1086 | if (!list_empty(&old->mnt_expire)) |
| 1087 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 1088 | } |
| 1089 | |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1090 | return mnt; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1091 | |
| 1092 | out_free: |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 1093 | mnt_free_id(mnt); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1094 | free_vfsmnt(mnt); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1095 | return ERR_PTR(err); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1096 | } |
| 1097 | |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1098 | static void cleanup_mnt(struct mount *mnt) |
| 1099 | { |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1100 | struct hlist_node *p; |
| 1101 | struct mount *m; |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1102 | /* |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1103 | * The warning here probably indicates that somebody messed |
| 1104 | * up a mnt_want/drop_write() pair. If this happens, the |
| 1105 | * filesystem was probably unable to make r/w->r/o transitions. |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1106 | * The locking used to deal with mnt_count decrement provides barriers, |
| 1107 | * so mnt_get_writers() below is safe. |
| 1108 | */ |
| 1109 | WARN_ON(mnt_get_writers(mnt)); |
| 1110 | if (unlikely(mnt->mnt_pins.first)) |
| 1111 | mnt_pin_kill(mnt); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1112 | hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) { |
| 1113 | hlist_del(&m->mnt_umount); |
| 1114 | mntput(&m->mnt); |
| 1115 | } |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1116 | fsnotify_vfsmount_delete(&mnt->mnt); |
| 1117 | dput(mnt->mnt.mnt_root); |
| 1118 | deactivate_super(mnt->mnt.mnt_sb); |
| 1119 | mnt_free_id(mnt); |
| 1120 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); |
| 1121 | } |
| 1122 | |
| 1123 | static void __cleanup_mnt(struct rcu_head *head) |
| 1124 | { |
| 1125 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); |
| 1126 | } |
| 1127 | |
| 1128 | static LLIST_HEAD(delayed_mntput_list); |
| 1129 | static void delayed_mntput(struct work_struct *unused) |
| 1130 | { |
| 1131 | struct llist_node *node = llist_del_all(&delayed_mntput_list); |
Byungchul Park | 2978573 | 2017-08-07 17:44:45 +0900 | [diff] [blame] | 1132 | struct mount *m, *t; |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1133 | |
Byungchul Park | 2978573 | 2017-08-07 17:44:45 +0900 | [diff] [blame] | 1134 | llist_for_each_entry_safe(m, t, node, mnt_llist) |
| 1135 | cleanup_mnt(m); |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1136 | } |
| 1137 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); |
| 1138 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1139 | static void mntput_no_expire(struct mount *mnt) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1140 | { |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1141 | LIST_HEAD(list); |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 1142 | int count; |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1143 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1144 | rcu_read_lock(); |
Al Viro | 9ea0a46 | 2018-08-09 17:21:17 -0400 | [diff] [blame] | 1145 | if (likely(READ_ONCE(mnt->mnt_ns))) { |
| 1146 | /* |
| 1147 | * Since we don't do lock_mount_hash() here, |
| 1148 | * ->mnt_ns can change under us. However, if it's |
| 1149 | * non-NULL, then there's a reference that won't |
| 1150 | * be dropped until after an RCU delay done after |
| 1151 | * turning ->mnt_ns NULL. So if we observe it |
| 1152 | * non-NULL under rcu_read_lock(), the reference |
| 1153 | * we are dropping is not the final one. |
| 1154 | */ |
| 1155 | mnt_add_count(mnt, -1); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1156 | rcu_read_unlock(); |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 1157 | return; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1158 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1159 | lock_mount_hash(); |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 1160 | /* |
| 1161 | * make sure that if __legitimize_mnt() has not seen us grab |
| 1162 | * mount_lock, we'll see their refcount increment here. |
| 1163 | */ |
| 1164 | smp_mb(); |
Al Viro | 9ea0a46 | 2018-08-09 17:21:17 -0400 | [diff] [blame] | 1165 | mnt_add_count(mnt, -1); |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 1166 | count = mnt_get_count(mnt); |
| 1167 | if (count != 0) { |
| 1168 | WARN_ON(count < 0); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1169 | rcu_read_unlock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1170 | unlock_mount_hash(); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1171 | return; |
| 1172 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1173 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
| 1174 | rcu_read_unlock(); |
| 1175 | unlock_mount_hash(); |
| 1176 | return; |
| 1177 | } |
| 1178 | mnt->mnt.mnt_flags |= MNT_DOOMED; |
| 1179 | rcu_read_unlock(); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1180 | |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 1181 | list_del(&mnt->mnt_instance); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1182 | |
| 1183 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { |
| 1184 | struct mount *p, *tmp; |
| 1185 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1186 | __put_mountpoint(unhash_mnt(p), &list); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1187 | hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1188 | } |
| 1189 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1190 | unlock_mount_hash(); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1191 | shrink_dentry_list(&list); |
Al Viro | 649a795 | 2013-09-28 12:41:25 -0400 | [diff] [blame] | 1192 | |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1193 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
| 1194 | struct task_struct *task = current; |
| 1195 | if (likely(!(task->flags & PF_KTHREAD))) { |
| 1196 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); |
Jens Axboe | 91989c7 | 2020-10-16 09:02:26 -0600 | [diff] [blame] | 1197 | if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME)) |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1198 | return; |
| 1199 | } |
| 1200 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) |
| 1201 | schedule_delayed_work(&delayed_mntput_work, 1); |
| 1202 | return; |
| 1203 | } |
| 1204 | cleanup_mnt(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1205 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1206 | |
| 1207 | void mntput(struct vfsmount *mnt) |
| 1208 | { |
| 1209 | if (mnt) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1210 | struct mount *m = real_mount(mnt); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1211 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1212 | if (unlikely(m->mnt_expiry_mark)) |
| 1213 | m->mnt_expiry_mark = 0; |
| 1214 | mntput_no_expire(m); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1215 | } |
| 1216 | } |
| 1217 | EXPORT_SYMBOL(mntput); |
| 1218 | |
| 1219 | struct vfsmount *mntget(struct vfsmount *mnt) |
| 1220 | { |
| 1221 | if (mnt) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1222 | mnt_add_count(real_mount(mnt), 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1223 | return mnt; |
| 1224 | } |
| 1225 | EXPORT_SYMBOL(mntget); |
| 1226 | |
Ian Kent | c6609c0 | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1227 | /* path_is_mountpoint() - Check if path is a mount in the current |
| 1228 | * namespace. |
| 1229 | * |
| 1230 | * d_mountpoint() can only be used reliably to establish if a dentry is |
| 1231 | * not mounted in any namespace and that common case is handled inline. |
| 1232 | * d_mountpoint() isn't aware of the possibility there may be multiple |
| 1233 | * mounts using a given dentry in a different namespace. This function |
| 1234 | * checks if the passed in path is a mountpoint rather than the dentry |
| 1235 | * alone. |
| 1236 | */ |
| 1237 | bool path_is_mountpoint(const struct path *path) |
| 1238 | { |
| 1239 | unsigned seq; |
| 1240 | bool res; |
| 1241 | |
| 1242 | if (!d_mountpoint(path->dentry)) |
| 1243 | return false; |
| 1244 | |
| 1245 | rcu_read_lock(); |
| 1246 | do { |
| 1247 | seq = read_seqbegin(&mount_lock); |
| 1248 | res = __path_is_mountpoint(path); |
| 1249 | } while (read_seqretry(&mount_lock, seq)); |
| 1250 | rcu_read_unlock(); |
| 1251 | |
| 1252 | return res; |
| 1253 | } |
| 1254 | EXPORT_SYMBOL(path_is_mountpoint); |
| 1255 | |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 1256 | struct vfsmount *mnt_clone_internal(const struct path *path) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1257 | { |
Al Viro | 3064c35 | 2014-08-07 09:12:31 -0400 | [diff] [blame] | 1258 | struct mount *p; |
| 1259 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); |
| 1260 | if (IS_ERR(p)) |
| 1261 | return ERR_CAST(p); |
| 1262 | p->mnt.mnt_flags |= MNT_INTERNAL; |
| 1263 | return &p->mnt; |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1264 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1265 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1266 | #ifdef CONFIG_PROC_FS |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1267 | static struct mount *mnt_list_next(struct mnt_namespace *ns, |
| 1268 | struct list_head *p) |
| 1269 | { |
| 1270 | struct mount *mnt, *ret = NULL; |
| 1271 | |
| 1272 | lock_ns_list(ns); |
| 1273 | list_for_each_continue(p, &ns->list) { |
| 1274 | mnt = list_entry(p, typeof(*mnt), mnt_list); |
| 1275 | if (!mnt_is_cursor(mnt)) { |
| 1276 | ret = mnt; |
| 1277 | break; |
| 1278 | } |
| 1279 | } |
| 1280 | unlock_ns_list(ns); |
| 1281 | |
| 1282 | return ret; |
| 1283 | } |
| 1284 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1285 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1286 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 1287 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1288 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1289 | struct list_head *prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1290 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1291 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1292 | if (!*pos) { |
| 1293 | prev = &p->ns->list; |
| 1294 | } else { |
| 1295 | prev = &p->cursor.mnt_list; |
| 1296 | |
| 1297 | /* Read after we'd reached the end? */ |
| 1298 | if (list_empty(prev)) |
| 1299 | return NULL; |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 1300 | } |
| 1301 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1302 | return mnt_list_next(p->ns, prev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1303 | } |
| 1304 | |
| 1305 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 1306 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1307 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1308 | struct mount *mnt = v; |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 1309 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1310 | ++*pos; |
| 1311 | return mnt_list_next(p->ns, &mnt->mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1312 | } |
| 1313 | |
| 1314 | static void m_stop(struct seq_file *m, void *v) |
| 1315 | { |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1316 | struct proc_mounts *p = m->private; |
| 1317 | struct mount *mnt = v; |
| 1318 | |
| 1319 | lock_ns_list(p->ns); |
| 1320 | if (mnt) |
| 1321 | list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); |
| 1322 | else |
| 1323 | list_del_init(&p->cursor.mnt_list); |
| 1324 | unlock_ns_list(p->ns); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1325 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1326 | } |
| 1327 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1328 | static int m_show(struct seq_file *m, void *v) |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 1329 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1330 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1331 | struct mount *r = v; |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1332 | return p->show(m, &r->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1333 | } |
| 1334 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1335 | const struct seq_operations mounts_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1336 | .start = m_start, |
| 1337 | .next = m_next, |
| 1338 | .stop = m_stop, |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1339 | .show = m_show, |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1340 | }; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1341 | |
| 1342 | void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) |
| 1343 | { |
| 1344 | down_read(&namespace_sem); |
| 1345 | lock_ns_list(ns); |
| 1346 | list_del(&cursor->mnt_list); |
| 1347 | unlock_ns_list(ns); |
| 1348 | up_read(&namespace_sem); |
| 1349 | } |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1350 | #endif /* CONFIG_PROC_FS */ |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1351 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | /** |
| 1353 | * may_umount_tree - check if a mount tree is busy |
| 1354 | * @mnt: root of mount tree |
| 1355 | * |
| 1356 | * This is called to check if a tree of mounts has any |
| 1357 | * open files, pwds, chroots or sub mounts that are |
| 1358 | * busy. |
| 1359 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1360 | int may_umount_tree(struct vfsmount *m) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1361 | { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1362 | struct mount *mnt = real_mount(m); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1363 | int actual_refs = 0; |
| 1364 | int minimum_refs = 0; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1365 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1366 | BUG_ON(!m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1367 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1368 | /* write lock needed for mnt_get_count */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1369 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1370 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1371 | actual_refs += mnt_get_count(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1372 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1373 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1374 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1375 | |
| 1376 | if (actual_refs > minimum_refs) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1377 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1378 | |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1379 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1380 | } |
| 1381 | |
| 1382 | EXPORT_SYMBOL(may_umount_tree); |
| 1383 | |
| 1384 | /** |
| 1385 | * may_umount - check if a mount point is busy |
| 1386 | * @mnt: root of mount |
| 1387 | * |
| 1388 | * This is called to check if a mount point has any |
| 1389 | * open files, pwds, chroots or sub mounts. If the |
| 1390 | * mount has sub mounts this will return busy |
| 1391 | * regardless of whether the sub mounts are busy. |
| 1392 | * |
| 1393 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 1394 | * give false negatives. The main reason why it's here is that we need |
| 1395 | * a non-destructive way to look for easily umountable filesystems. |
| 1396 | */ |
| 1397 | int may_umount(struct vfsmount *mnt) |
| 1398 | { |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1399 | int ret = 1; |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1400 | down_read(&namespace_sem); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1401 | lock_mount_hash(); |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1402 | if (propagate_mount_busy(real_mount(mnt), 2)) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1403 | ret = 0; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1404 | unlock_mount_hash(); |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1405 | up_read(&namespace_sem); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1406 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1407 | } |
| 1408 | |
| 1409 | EXPORT_SYMBOL(may_umount); |
| 1410 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1411 | static void namespace_unlock(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1412 | { |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1413 | struct hlist_head head; |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1414 | struct hlist_node *p; |
| 1415 | struct mount *m; |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1416 | LIST_HEAD(list); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1417 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1418 | hlist_move_list(&unmounted, &head); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1419 | list_splice_init(&ex_mountpoints, &list); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1420 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1421 | up_write(&namespace_sem); |
| 1422 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1423 | shrink_dentry_list(&list); |
| 1424 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1425 | if (likely(hlist_empty(&head))) |
| 1426 | return; |
| 1427 | |
NeilBrown | 22cb740 | 2018-11-30 10:33:18 +1100 | [diff] [blame] | 1428 | synchronize_rcu_expedited(); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1429 | |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1430 | hlist_for_each_entry_safe(m, p, &head, mnt_umount) { |
| 1431 | hlist_del(&m->mnt_umount); |
| 1432 | mntput(&m->mnt); |
| 1433 | } |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1434 | } |
| 1435 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1436 | static inline void namespace_lock(void) |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1437 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1438 | down_write(&namespace_sem); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1439 | } |
| 1440 | |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1441 | enum umount_tree_flags { |
| 1442 | UMOUNT_SYNC = 1, |
| 1443 | UMOUNT_PROPAGATE = 2, |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1444 | UMOUNT_CONNECTED = 4, |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1445 | }; |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1446 | |
| 1447 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) |
| 1448 | { |
| 1449 | /* Leaving mounts connected is only valid for lazy umounts */ |
| 1450 | if (how & UMOUNT_SYNC) |
| 1451 | return true; |
| 1452 | |
| 1453 | /* A mount without a parent has nothing to be connected to */ |
| 1454 | if (!mnt_has_parent(mnt)) |
| 1455 | return true; |
| 1456 | |
| 1457 | /* Because the reference counting rules change when mounts are |
| 1458 | * unmounted and connected, umounted mounts may not be |
| 1459 | * connected to mounted mounts. |
| 1460 | */ |
| 1461 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) |
| 1462 | return true; |
| 1463 | |
| 1464 | /* Has it been requested that the mount remain connected? */ |
| 1465 | if (how & UMOUNT_CONNECTED) |
| 1466 | return false; |
| 1467 | |
| 1468 | /* Is the mount locked such that it needs to remain connected? */ |
| 1469 | if (IS_MNT_LOCKED(mnt)) |
| 1470 | return false; |
| 1471 | |
| 1472 | /* By default disconnect the mount */ |
| 1473 | return true; |
| 1474 | } |
| 1475 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1476 | /* |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1477 | * mount_lock must be held |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1478 | * namespace_sem must be held for write |
| 1479 | */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1480 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1481 | { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1482 | LIST_HEAD(tmp_list); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1483 | struct mount *p; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1484 | |
Eric W. Biederman | 5d88457 | 2015-01-03 05:39:35 -0600 | [diff] [blame] | 1485 | if (how & UMOUNT_PROPAGATE) |
| 1486 | propagate_mount_unlock(mnt); |
| 1487 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1488 | /* Gather the mounts to umount */ |
Eric W. Biederman | 590ce4bc | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1489 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1490 | p->mnt.mnt_flags |= MNT_UMOUNT; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1491 | list_move(&p->mnt_list, &tmp_list); |
Eric W. Biederman | 590ce4bc | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1492 | } |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1493 | |
Eric W. Biederman | 411a938 | 2014-12-22 19:12:07 -0600 | [diff] [blame] | 1494 | /* Hide the mounts from mnt_mounts */ |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1495 | list_for_each_entry(p, &tmp_list, mnt_list) { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1496 | list_del_init(&p->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1497 | } |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1498 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1499 | /* Add propogated mounts to the tmp_list */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1500 | if (how & UMOUNT_PROPAGATE) |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1501 | propagate_umount(&tmp_list); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1502 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1503 | while (!list_empty(&tmp_list)) { |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1504 | struct mnt_namespace *ns; |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1505 | bool disconnect; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1506 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1507 | list_del_init(&p->mnt_expire); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1508 | list_del_init(&p->mnt_list); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1509 | ns = p->mnt_ns; |
| 1510 | if (ns) { |
| 1511 | ns->mounts--; |
| 1512 | __touch_mnt_namespace(ns); |
| 1513 | } |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1514 | p->mnt_ns = NULL; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1515 | if (how & UMOUNT_SYNC) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1516 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 1517 | |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1518 | disconnect = disconnect_mount(p, how); |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1519 | if (mnt_has_parent(p)) { |
Al Viro | 81b6b06 | 2014-08-30 18:32:05 -0400 | [diff] [blame] | 1520 | mnt_add_count(p->mnt_parent, -1); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1521 | if (!disconnect) { |
| 1522 | /* Don't forget about p */ |
| 1523 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); |
| 1524 | } else { |
| 1525 | umount_mnt(p); |
| 1526 | } |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1527 | } |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1528 | change_mnt_propagation(p, MS_PRIVATE); |
Al Viro | 19a1c40 | 2019-07-24 12:45:46 -0400 | [diff] [blame] | 1529 | if (disconnect) |
| 1530 | hlist_add_head(&p->mnt_umount, &unmounted); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1531 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1532 | } |
| 1533 | |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 1534 | static void shrink_submounts(struct mount *mnt); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1535 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 1536 | static int do_umount_root(struct super_block *sb) |
| 1537 | { |
| 1538 | int ret = 0; |
| 1539 | |
| 1540 | down_write(&sb->s_umount); |
| 1541 | if (!sb_rdonly(sb)) { |
| 1542 | struct fs_context *fc; |
| 1543 | |
| 1544 | fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY, |
| 1545 | SB_RDONLY); |
| 1546 | if (IS_ERR(fc)) { |
| 1547 | ret = PTR_ERR(fc); |
| 1548 | } else { |
| 1549 | ret = parse_monolithic_mount_data(fc, NULL); |
| 1550 | if (!ret) |
| 1551 | ret = reconfigure_super(fc); |
| 1552 | put_fs_context(fc); |
| 1553 | } |
| 1554 | } |
| 1555 | up_write(&sb->s_umount); |
| 1556 | return ret; |
| 1557 | } |
| 1558 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1559 | static int do_umount(struct mount *mnt, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1560 | { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1561 | struct super_block *sb = mnt->mnt.mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1562 | int retval; |
| 1563 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1564 | retval = security_sb_umount(&mnt->mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1565 | if (retval) |
| 1566 | return retval; |
| 1567 | |
| 1568 | /* |
| 1569 | * Allow userspace to request a mountpoint be expired rather than |
| 1570 | * unmounting unconditionally. Unmount only happens if: |
| 1571 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 1572 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 1573 | */ |
| 1574 | if (flags & MNT_EXPIRE) { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1575 | if (&mnt->mnt == current->fs->root.mnt || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1576 | flags & (MNT_FORCE | MNT_DETACH)) |
| 1577 | return -EINVAL; |
| 1578 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1579 | /* |
| 1580 | * probably don't strictly need the lock here if we examined |
| 1581 | * all race cases, but it's a slowpath. |
| 1582 | */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1583 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1584 | if (mnt_get_count(mnt) != 2) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1585 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1586 | return -EBUSY; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1587 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1588 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1589 | |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1590 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1591 | return -EAGAIN; |
| 1592 | } |
| 1593 | |
| 1594 | /* |
| 1595 | * If we may have to abort operations to get out of this |
| 1596 | * mount, and they will themselves hold resources we must |
| 1597 | * allow the fs to do things. In the Unix tradition of |
| 1598 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 1599 | * might fail to complete on the first run through as other tasks |
| 1600 | * must return, and the like. Thats for the mount program to worry |
| 1601 | * about for the moment. |
| 1602 | */ |
| 1603 | |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1604 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1605 | sb->s_op->umount_begin(sb); |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1606 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1607 | |
| 1608 | /* |
| 1609 | * No sense to grab the lock for this test, but test itself looks |
| 1610 | * somewhat bogus. Suggestions for better replacement? |
| 1611 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1612 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1613 | * Actually it makes sense, especially if rootfs would contain a |
| 1614 | * /reboot - static binary that would close all descriptors and |
| 1615 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1616 | */ |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1617 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1618 | /* |
| 1619 | * Special case for "unmounting" root ... |
| 1620 | * we just try to remount it readonly. |
| 1621 | */ |
Eric W. Biederman | bc6155d | 2017-09-18 17:58:08 -0500 | [diff] [blame] | 1622 | if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) |
Andy Lutomirski | a1480dc | 2014-10-08 12:32:47 -0700 | [diff] [blame] | 1623 | return -EPERM; |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 1624 | return do_umount_root(sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1625 | } |
| 1626 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1627 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1628 | lock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1629 | |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1630 | /* Recheck MNT_LOCKED with the locks held */ |
| 1631 | retval = -EINVAL; |
| 1632 | if (mnt->mnt.mnt_flags & MNT_LOCKED) |
| 1633 | goto out; |
| 1634 | |
| 1635 | event++; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1636 | if (flags & MNT_DETACH) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1637 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1638 | umount_tree(mnt, UMOUNT_PROPAGATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1639 | retval = 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1640 | } else { |
| 1641 | shrink_submounts(mnt); |
| 1642 | retval = -EBUSY; |
| 1643 | if (!propagate_mount_busy(mnt, 2)) { |
| 1644 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1645 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1646 | retval = 0; |
| 1647 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1648 | } |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1649 | out: |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1650 | unlock_mount_hash(); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1651 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1652 | return retval; |
| 1653 | } |
| 1654 | |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1655 | /* |
| 1656 | * __detach_mounts - lazily unmount all mounts on the specified dentry |
| 1657 | * |
| 1658 | * During unlink, rmdir, and d_drop it is possible to loose the path |
| 1659 | * to an existing mountpoint, and wind up leaking the mount. |
| 1660 | * detach_mounts allows lazily unmounting those mounts instead of |
| 1661 | * leaking them. |
| 1662 | * |
| 1663 | * The caller may hold dentry->d_inode->i_mutex. |
| 1664 | */ |
| 1665 | void __detach_mounts(struct dentry *dentry) |
| 1666 | { |
| 1667 | struct mountpoint *mp; |
| 1668 | struct mount *mnt; |
| 1669 | |
| 1670 | namespace_lock(); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1671 | lock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1672 | mp = lookup_mountpoint(dentry); |
Al Viro | adc9b5c | 2019-06-29 12:06:51 -0400 | [diff] [blame] | 1673 | if (!mp) |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1674 | goto out_unlock; |
| 1675 | |
Andrey Ulanov | e06b933 | 2016-04-15 14:24:41 -0700 | [diff] [blame] | 1676 | event++; |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1677 | while (!hlist_empty(&mp->m_list)) { |
| 1678 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1679 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
Eric W. Biederman | fe78fcc8 | 2015-07-17 14:54:27 -0500 | [diff] [blame] | 1680 | umount_mnt(mnt); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1681 | hlist_add_head(&mnt->mnt_umount, &unmounted); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1682 | } |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1683 | else umount_tree(mnt, UMOUNT_CONNECTED); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1684 | } |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1685 | put_mountpoint(mp); |
| 1686 | out_unlock: |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1687 | unlock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1688 | namespace_unlock(); |
| 1689 | } |
| 1690 | |
David Howells | dd111b3 | 2017-07-04 17:25:09 +0100 | [diff] [blame] | 1691 | /* |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1692 | * Is the caller allowed to modify his namespace? |
| 1693 | */ |
| 1694 | static inline bool may_mount(void) |
| 1695 | { |
| 1696 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); |
| 1697 | } |
| 1698 | |
Jeff Layton | df2474a | 2019-08-15 15:21:17 -0400 | [diff] [blame] | 1699 | #ifdef CONFIG_MANDATORY_FILE_LOCKING |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1700 | static inline bool may_mandlock(void) |
| 1701 | { |
Eric W. Biederman | 95ace75 | 2015-11-11 17:22:33 -0600 | [diff] [blame] | 1702 | return capable(CAP_SYS_ADMIN); |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1703 | } |
Jeff Layton | df2474a | 2019-08-15 15:21:17 -0400 | [diff] [blame] | 1704 | #else |
| 1705 | static inline bool may_mandlock(void) |
| 1706 | { |
| 1707 | pr_warn("VFS: \"mand\" mount option not supported"); |
| 1708 | return false; |
| 1709 | } |
| 1710 | #endif |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1711 | |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1712 | static int can_umount(const struct path *path, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1713 | { |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1714 | struct mount *mnt = real_mount(path->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1715 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1716 | if (!may_mount()) |
| 1717 | return -EPERM; |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1718 | if (path->dentry != path->mnt->mnt_root) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1719 | return -EINVAL; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1720 | if (!check_mnt(mnt)) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1721 | return -EINVAL; |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1722 | if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1723 | return -EINVAL; |
Eric W. Biederman | b2f5d4d | 2014-10-04 14:44:03 -0700 | [diff] [blame] | 1724 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1725 | return -EPERM; |
| 1726 | return 0; |
| 1727 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1728 | |
Al Viro | a0a6df9 | 2021-01-04 15:25:34 -0500 | [diff] [blame] | 1729 | // caller is responsible for flags being sane |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1730 | int path_umount(struct path *path, int flags) |
| 1731 | { |
| 1732 | struct mount *mnt = real_mount(path->mnt); |
| 1733 | int ret; |
| 1734 | |
| 1735 | ret = can_umount(path, flags); |
| 1736 | if (!ret) |
| 1737 | ret = do_umount(mnt, flags); |
| 1738 | |
Jan Blunck | 429731b | 2008-02-14 19:34:31 -0800 | [diff] [blame] | 1739 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1740 | dput(path->dentry); |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1741 | mntput_no_expire(mnt); |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1742 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1743 | } |
| 1744 | |
Christoph Hellwig | 09267de | 2020-07-23 08:23:08 +0200 | [diff] [blame] | 1745 | static int ksys_umount(char __user *name, int flags) |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1746 | { |
| 1747 | int lookup_flags = LOOKUP_MOUNTPOINT; |
| 1748 | struct path path; |
| 1749 | int ret; |
| 1750 | |
Al Viro | a0a6df9 | 2021-01-04 15:25:34 -0500 | [diff] [blame] | 1751 | // basic validity checks done first |
| 1752 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
| 1753 | return -EINVAL; |
| 1754 | |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1755 | if (!(flags & UMOUNT_NOFOLLOW)) |
| 1756 | lookup_flags |= LOOKUP_FOLLOW; |
| 1757 | ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); |
| 1758 | if (ret) |
| 1759 | return ret; |
| 1760 | return path_umount(&path, flags); |
| 1761 | } |
| 1762 | |
Dominik Brodowski | 3a18ef5 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1763 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
| 1764 | { |
| 1765 | return ksys_umount(name, flags); |
| 1766 | } |
| 1767 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1768 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1769 | |
| 1770 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1771 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1772 | */ |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1773 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1774 | { |
Dominik Brodowski | 3a18ef5 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1775 | return ksys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1776 | } |
| 1777 | |
| 1778 | #endif |
| 1779 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1780 | static bool is_mnt_ns_file(struct dentry *dentry) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1781 | { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1782 | /* Is this a proxy for a mount namespace? */ |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 1783 | return dentry->d_op == &ns_dentry_operations && |
| 1784 | dentry->d_fsdata == &mntns_operations; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1785 | } |
| 1786 | |
Eric Biggers | 213921f | 2020-01-04 12:59:55 -0800 | [diff] [blame] | 1787 | static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 1788 | { |
| 1789 | return container_of(ns, struct mnt_namespace, ns); |
| 1790 | } |
| 1791 | |
Christian Brauner | 303cc57 | 2020-05-05 16:04:31 +0200 | [diff] [blame] | 1792 | struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) |
| 1793 | { |
| 1794 | return &mnt->ns; |
| 1795 | } |
| 1796 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1797 | static bool mnt_ns_loop(struct dentry *dentry) |
| 1798 | { |
| 1799 | /* Could bind mounting the mount namespace inode cause a |
| 1800 | * mount namespace loop? |
| 1801 | */ |
| 1802 | struct mnt_namespace *mnt_ns; |
| 1803 | if (!is_mnt_ns_file(dentry)) |
| 1804 | return false; |
| 1805 | |
Al Viro | f77c801 | 2014-11-01 03:13:17 -0400 | [diff] [blame] | 1806 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1807 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
| 1808 | } |
| 1809 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1810 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1811 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1812 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1813 | struct mount *res, *p, *q, *r, *parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1814 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1815 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
| 1816 | return ERR_PTR(-EINVAL); |
| 1817 | |
| 1818 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1819 | return ERR_PTR(-EINVAL); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1820 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1821 | res = q = clone_mnt(mnt, dentry, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1822 | if (IS_ERR(q)) |
| 1823 | return q; |
| 1824 | |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1825 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1826 | |
| 1827 | p = mnt; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1828 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1829 | struct mount *s; |
Jan Blunck | 7ec02ef | 2008-04-29 00:59:40 -0700 | [diff] [blame] | 1830 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1831 | continue; |
| 1832 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1833 | for (s = r; s; s = next_mnt(s, r)) { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1834 | if (!(flag & CL_COPY_UNBINDABLE) && |
| 1835 | IS_MNT_UNBINDABLE(s)) { |
Eric W. Biederman | df7342b | 2018-10-25 09:04:18 -0500 | [diff] [blame] | 1836 | if (s->mnt.mnt_flags & MNT_LOCKED) { |
| 1837 | /* Both unbindable and locked. */ |
| 1838 | q = ERR_PTR(-EPERM); |
| 1839 | goto out; |
| 1840 | } else { |
| 1841 | s = skip_mnt_tree(s); |
| 1842 | continue; |
| 1843 | } |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1844 | } |
| 1845 | if (!(flag & CL_COPY_MNT_NS_FILE) && |
| 1846 | is_mnt_ns_file(s->mnt.mnt_root)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1847 | s = skip_mnt_tree(s); |
| 1848 | continue; |
| 1849 | } |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1850 | while (p != s->mnt_parent) { |
| 1851 | p = p->mnt_parent; |
| 1852 | q = q->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1853 | } |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1854 | p = s; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1855 | parent = q; |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1856 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1857 | if (IS_ERR(q)) |
| 1858 | goto out; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1859 | lock_mount_hash(); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1860 | list_add_tail(&q->mnt_list, &res->mnt_list); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1861 | attach_mnt(q, parent, p->mnt_mp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1862 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1863 | } |
| 1864 | } |
| 1865 | return res; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1866 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1867 | if (res) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1868 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1869 | umount_tree(res, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1870 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1871 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1872 | return q; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1873 | } |
| 1874 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1875 | /* Caller should check returned pointer for errors */ |
| 1876 | |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 1877 | struct vfsmount *collect_mounts(const struct path *path) |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1878 | { |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1879 | struct mount *tree; |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1880 | namespace_lock(); |
Eric W. Biederman | cd4a401 | 2015-01-07 14:28:26 -0600 | [diff] [blame] | 1881 | if (!check_mnt(real_mount(path->mnt))) |
| 1882 | tree = ERR_PTR(-EINVAL); |
| 1883 | else |
| 1884 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
| 1885 | CL_COPY_ALL | CL_PRIVATE); |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 1886 | namespace_unlock(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1887 | if (IS_ERR(tree)) |
Dan Carpenter | 52e220d | 2013-08-14 12:44:39 +0300 | [diff] [blame] | 1888 | return ERR_CAST(tree); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1889 | return &tree->mnt; |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1890 | } |
| 1891 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 1892 | static void free_mnt_ns(struct mnt_namespace *); |
| 1893 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool); |
| 1894 | |
| 1895 | void dissolve_on_fput(struct vfsmount *mnt) |
| 1896 | { |
| 1897 | struct mnt_namespace *ns; |
| 1898 | namespace_lock(); |
| 1899 | lock_mount_hash(); |
| 1900 | ns = real_mount(mnt)->mnt_ns; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 1901 | if (ns) { |
| 1902 | if (is_anon_ns(ns)) |
| 1903 | umount_tree(real_mount(mnt), UMOUNT_CONNECTED); |
| 1904 | else |
| 1905 | ns = NULL; |
| 1906 | } |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 1907 | unlock_mount_hash(); |
| 1908 | namespace_unlock(); |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 1909 | if (ns) |
| 1910 | free_mnt_ns(ns); |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 1911 | } |
| 1912 | |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1913 | void drop_collected_mounts(struct vfsmount *mnt) |
| 1914 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1915 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1916 | lock_mount_hash(); |
Eric W. Biederman | 9c8e0a1 | 2018-10-25 12:05:11 -0500 | [diff] [blame] | 1917 | umount_tree(real_mount(mnt), 0); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1918 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 1919 | namespace_unlock(); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1920 | } |
| 1921 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1922 | /** |
| 1923 | * clone_private_mount - create a private clone of a path |
| 1924 | * |
| 1925 | * This creates a new vfsmount, which will be the clone of @path. The new will |
| 1926 | * not be attached anywhere in the namespace and will be private (i.e. changes |
| 1927 | * to the originating mount won't be propagated into this). |
| 1928 | * |
| 1929 | * Release with mntput(). |
| 1930 | */ |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 1931 | struct vfsmount *clone_private_mount(const struct path *path) |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1932 | { |
| 1933 | struct mount *old_mnt = real_mount(path->mnt); |
| 1934 | struct mount *new_mnt; |
| 1935 | |
| 1936 | if (IS_MNT_UNBINDABLE(old_mnt)) |
| 1937 | return ERR_PTR(-EINVAL); |
| 1938 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1939 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1940 | if (IS_ERR(new_mnt)) |
| 1941 | return ERR_CAST(new_mnt); |
| 1942 | |
Miklos Szeredi | df820f8 | 2020-06-04 10:48:19 +0200 | [diff] [blame] | 1943 | /* Longterm mount to be removed by kern_unmount*() */ |
| 1944 | new_mnt->mnt_ns = MNT_NS_INTERNAL; |
| 1945 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 1946 | return &new_mnt->mnt; |
| 1947 | } |
| 1948 | EXPORT_SYMBOL_GPL(clone_private_mount); |
| 1949 | |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1950 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
| 1951 | struct vfsmount *root) |
| 1952 | { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1953 | struct mount *mnt; |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1954 | int res = f(root, arg); |
| 1955 | if (res) |
| 1956 | return res; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1957 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
| 1958 | res = f(&mnt->mnt, arg); |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1959 | if (res) |
| 1960 | return res; |
| 1961 | } |
| 1962 | return 0; |
| 1963 | } |
| 1964 | |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 1965 | static void lock_mnt_tree(struct mount *mnt) |
| 1966 | { |
| 1967 | struct mount *p; |
| 1968 | |
| 1969 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1970 | int flags = p->mnt.mnt_flags; |
| 1971 | /* Don't allow unprivileged users to change mount flags */ |
| 1972 | flags |= MNT_LOCK_ATIME; |
| 1973 | |
| 1974 | if (flags & MNT_READONLY) |
| 1975 | flags |= MNT_LOCK_READONLY; |
| 1976 | |
| 1977 | if (flags & MNT_NODEV) |
| 1978 | flags |= MNT_LOCK_NODEV; |
| 1979 | |
| 1980 | if (flags & MNT_NOSUID) |
| 1981 | flags |= MNT_LOCK_NOSUID; |
| 1982 | |
| 1983 | if (flags & MNT_NOEXEC) |
| 1984 | flags |= MNT_LOCK_NOEXEC; |
| 1985 | /* Don't allow unprivileged users to reveal what is under a mount */ |
| 1986 | if (list_empty(&p->mnt_expire)) |
| 1987 | flags |= MNT_LOCKED; |
| 1988 | p->mnt.mnt_flags = flags; |
| 1989 | } |
| 1990 | } |
| 1991 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1992 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1993 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1994 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1995 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1996 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1997 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1998 | mnt_release_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1999 | } |
| 2000 | } |
| 2001 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2002 | static int invent_group_ids(struct mount *mnt, bool recurse) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2003 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2004 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2005 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2006 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2007 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2008 | int err = mnt_alloc_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2009 | if (err) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2010 | cleanup_group_ids(mnt, p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2011 | return err; |
| 2012 | } |
| 2013 | } |
| 2014 | } |
| 2015 | |
| 2016 | return 0; |
| 2017 | } |
| 2018 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2019 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
| 2020 | { |
| 2021 | unsigned int max = READ_ONCE(sysctl_mount_max); |
| 2022 | unsigned int mounts = 0, old, pending, sum; |
| 2023 | struct mount *p; |
| 2024 | |
| 2025 | for (p = mnt; p; p = next_mnt(p, mnt)) |
| 2026 | mounts++; |
| 2027 | |
| 2028 | old = ns->mounts; |
| 2029 | pending = ns->pending_mounts; |
| 2030 | sum = old + pending; |
| 2031 | if ((old > sum) || |
| 2032 | (pending > sum) || |
| 2033 | (max < sum) || |
| 2034 | (mounts > (max - sum))) |
| 2035 | return -ENOSPC; |
| 2036 | |
| 2037 | ns->pending_mounts = pending + mounts; |
| 2038 | return 0; |
| 2039 | } |
| 2040 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2041 | /* |
| 2042 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2043 | * @nd : place the mount tree @source_mnt is attached |
| 2044 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 2045 | * store the parent mount and mountpoint dentry. |
| 2046 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2047 | * |
| 2048 | * NOTE: in the table below explains the semantics when a source mount |
| 2049 | * of a given type is attached to a destination mount of a given type. |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2050 | * --------------------------------------------------------------------------- |
| 2051 | * | BIND MOUNT OPERATION | |
| 2052 | * |************************************************************************** |
| 2053 | * | source-->| shared | private | slave | unbindable | |
| 2054 | * | dest | | | | | |
| 2055 | * | | | | | | | |
| 2056 | * | v | | | | | |
| 2057 | * |************************************************************************** |
| 2058 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 2059 | * | | | | | | |
| 2060 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 2061 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2062 | * A bind operation clones the source mount and mounts the clone on the |
| 2063 | * destination mount. |
| 2064 | * |
| 2065 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 2066 | * tree of the destination mount and the cloned mount is added to |
| 2067 | * the peer group of the source mount. |
| 2068 | * (+) the cloned mount is created under the destination mount and is marked |
| 2069 | * as shared. The cloned mount is added to the peer group of the source |
| 2070 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2071 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 2072 | * of the destination mount and the cloned mount is made slave |
| 2073 | * of the same master as that of the source mount. The cloned mount |
| 2074 | * is marked as 'shared and slave'. |
| 2075 | * (*) the cloned mount is made a slave of the same master as that of the |
| 2076 | * source mount. |
| 2077 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2078 | * --------------------------------------------------------------------------- |
| 2079 | * | MOVE MOUNT OPERATION | |
| 2080 | * |************************************************************************** |
| 2081 | * | source-->| shared | private | slave | unbindable | |
| 2082 | * | dest | | | | | |
| 2083 | * | | | | | | | |
| 2084 | * | v | | | | | |
| 2085 | * |************************************************************************** |
| 2086 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 2087 | * | | | | | | |
| 2088 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 2089 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2090 | * |
| 2091 | * (+) the mount is moved to the destination. And is then propagated to |
| 2092 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2093 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2094 | * (+++) the mount is moved to the destination and is then propagated to |
| 2095 | * all the mounts belonging to the destination mount's propagation tree. |
| 2096 | * the mount is marked as 'shared and slave'. |
| 2097 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2098 | * |
| 2099 | * if the source mount is a tree, the operations explained above is |
| 2100 | * applied to each mount in the tree. |
| 2101 | * Must be called without spinlocks held, since this function can sleep |
| 2102 | * in allocations. |
| 2103 | */ |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2104 | static int attach_recursive_mnt(struct mount *source_mnt, |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2105 | struct mount *dest_mnt, |
| 2106 | struct mountpoint *dest_mp, |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2107 | bool moving) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2108 | { |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 2109 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2110 | HLIST_HEAD(tree_list); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2111 | struct mnt_namespace *ns = dest_mnt->mnt_ns; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2112 | struct mountpoint *smp; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2113 | struct mount *child, *p; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2114 | struct hlist_node *n; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2115 | int err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2116 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2117 | /* Preallocate a mountpoint in case the new mounts need |
| 2118 | * to be tucked under other mounts. |
| 2119 | */ |
| 2120 | smp = get_mountpoint(source_mnt->mnt.mnt_root); |
| 2121 | if (IS_ERR(smp)) |
| 2122 | return PTR_ERR(smp); |
| 2123 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2124 | /* Is there space to add these mounts to the mount namespace? */ |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2125 | if (!moving) { |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2126 | err = count_mounts(ns, source_mnt); |
| 2127 | if (err) |
| 2128 | goto out; |
| 2129 | } |
| 2130 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2131 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2132 | err = invent_group_ids(source_mnt, true); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2133 | if (err) |
| 2134 | goto out; |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2135 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2136 | lock_mount_hash(); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2137 | if (err) |
| 2138 | goto out_cleanup_ids; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2139 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2140 | set_mnt_shared(p); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2141 | } else { |
| 2142 | lock_mount_hash(); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2143 | } |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2144 | if (moving) { |
| 2145 | unhash_mnt(source_mnt); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2146 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2147 | touch_mnt_namespace(source_mnt->mnt_ns); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2148 | } else { |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2149 | if (source_mnt->mnt_ns) { |
| 2150 | /* move from anon - the caller will destroy */ |
| 2151 | list_del_init(&source_mnt->mnt_ns->list); |
| 2152 | } |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2153 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2154 | commit_tree(source_mnt); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2155 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2156 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2157 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
Al Viro | 1d6a32a | 2014-03-20 20:34:43 -0400 | [diff] [blame] | 2158 | struct mount *q; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2159 | hlist_del_init(&child->mnt_hash); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2160 | q = __lookup_mnt(&child->mnt_parent->mnt, |
| 2161 | child->mnt_mountpoint); |
| 2162 | if (q) |
| 2163 | mnt_change_mountpoint(child, smp, q); |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 2164 | /* Notice when we are propagating across user namespaces */ |
| 2165 | if (child->mnt_parent->mnt_ns->user_ns != user_ns) |
| 2166 | lock_mnt_tree(child); |
Christian Brauner | d728cf7 | 2019-06-17 23:22:14 +0200 | [diff] [blame] | 2167 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2168 | commit_tree(child); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2169 | } |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2170 | put_mountpoint(smp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2171 | unlock_mount_hash(); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2172 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2173 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2174 | |
| 2175 | out_cleanup_ids: |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2176 | while (!hlist_empty(&tree_list)) { |
| 2177 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2178 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2179 | umount_tree(child, UMOUNT_SYNC); |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2180 | } |
| 2181 | unlock_mount_hash(); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2182 | cleanup_group_ids(source_mnt, NULL); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2183 | out: |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2184 | ns->pending_mounts = 0; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2185 | |
| 2186 | read_seqlock_excl(&mount_lock); |
| 2187 | put_mountpoint(smp); |
| 2188 | read_sequnlock_excl(&mount_lock); |
| 2189 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2190 | return err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2191 | } |
| 2192 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2193 | static struct mountpoint *lock_mount(struct path *path) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2194 | { |
| 2195 | struct vfsmount *mnt; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2196 | struct dentry *dentry = path->dentry; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2197 | retry: |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2198 | inode_lock(dentry->d_inode); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2199 | if (unlikely(cant_mount(dentry))) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2200 | inode_unlock(dentry->d_inode); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2201 | return ERR_PTR(-ENOENT); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2202 | } |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2203 | namespace_lock(); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2204 | mnt = lookup_mnt(path); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2205 | if (likely(!mnt)) { |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2206 | struct mountpoint *mp = get_mountpoint(dentry); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2207 | if (IS_ERR(mp)) { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2208 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2209 | inode_unlock(dentry->d_inode); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2210 | return mp; |
| 2211 | } |
| 2212 | return mp; |
| 2213 | } |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2214 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2215 | inode_unlock(path->dentry->d_inode); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2216 | path_put(path); |
| 2217 | path->mnt = mnt; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2218 | dentry = path->dentry = dget(mnt->mnt_root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2219 | goto retry; |
| 2220 | } |
| 2221 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2222 | static void unlock_mount(struct mountpoint *where) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2223 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2224 | struct dentry *dentry = where->m_dentry; |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2225 | |
| 2226 | read_seqlock_excl(&mount_lock); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2227 | put_mountpoint(where); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2228 | read_sequnlock_excl(&mount_lock); |
| 2229 | |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2230 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2231 | inode_unlock(dentry->d_inode); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2232 | } |
| 2233 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2234 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2235 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2236 | if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2237 | return -EINVAL; |
| 2238 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2239 | if (d_is_dir(mp->m_dentry) != |
| 2240 | d_is_dir(mnt->mnt.mnt_root)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2241 | return -ENOTDIR; |
| 2242 | |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2243 | return attach_recursive_mnt(mnt, p, mp, false); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2244 | } |
| 2245 | |
| 2246 | /* |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2247 | * Sanity check the flags to change_mnt_propagation. |
| 2248 | */ |
| 2249 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2250 | static int flags_to_propagation_type(int ms_flags) |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2251 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2252 | int type = ms_flags & ~(MS_REC | MS_SILENT); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2253 | |
| 2254 | /* Fail if any non-propagation flags are set */ |
| 2255 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 2256 | return 0; |
| 2257 | /* Only one propagation flag should be set */ |
| 2258 | if (!is_power_of_2(type)) |
| 2259 | return 0; |
| 2260 | return type; |
| 2261 | } |
| 2262 | |
| 2263 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2264 | * recursively change the type of the mountpoint. |
| 2265 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2266 | static int do_change_type(struct path *path, int ms_flags) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2267 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2268 | struct mount *m; |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2269 | struct mount *mnt = real_mount(path->mnt); |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2270 | int recurse = ms_flags & MS_REC; |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2271 | int type; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2272 | int err = 0; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2273 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2274 | if (path->dentry != path->mnt->mnt_root) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2275 | return -EINVAL; |
| 2276 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2277 | type = flags_to_propagation_type(ms_flags); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2278 | if (!type) |
| 2279 | return -EINVAL; |
| 2280 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2281 | namespace_lock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2282 | if (type == MS_SHARED) { |
| 2283 | err = invent_group_ids(mnt, recurse); |
| 2284 | if (err) |
| 2285 | goto out_unlock; |
| 2286 | } |
| 2287 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2288 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2289 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2290 | change_mnt_propagation(m, type); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2291 | unlock_mount_hash(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2292 | |
| 2293 | out_unlock: |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2294 | namespace_unlock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2295 | return err; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2296 | } |
| 2297 | |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 2298 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
| 2299 | { |
| 2300 | struct mount *child; |
| 2301 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 2302 | if (!is_subdir(child->mnt_mountpoint, dentry)) |
| 2303 | continue; |
| 2304 | |
| 2305 | if (child->mnt.mnt_flags & MNT_LOCKED) |
| 2306 | return true; |
| 2307 | } |
| 2308 | return false; |
| 2309 | } |
| 2310 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2311 | static struct mount *__do_loopback(struct path *old_path, int recurse) |
| 2312 | { |
| 2313 | struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt); |
| 2314 | |
| 2315 | if (IS_MNT_UNBINDABLE(old)) |
| 2316 | return mnt; |
| 2317 | |
| 2318 | if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) |
| 2319 | return mnt; |
| 2320 | |
| 2321 | if (!recurse && has_locked_children(old, old_path->dentry)) |
| 2322 | return mnt; |
| 2323 | |
| 2324 | if (recurse) |
| 2325 | mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE); |
| 2326 | else |
| 2327 | mnt = clone_mnt(old, old_path->dentry, 0); |
| 2328 | |
| 2329 | if (!IS_ERR(mnt)) |
| 2330 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 2331 | |
| 2332 | return mnt; |
| 2333 | } |
| 2334 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2335 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2336 | * do loopback mount. |
| 2337 | */ |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2338 | static int do_loopback(struct path *path, const char *old_name, |
Eric Sandeen | 2dafe1c | 2008-02-08 04:22:12 -0800 | [diff] [blame] | 2339 | int recurse) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2340 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2341 | struct path old_path; |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2342 | struct mount *mnt = NULL, *parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2343 | struct mountpoint *mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2344 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2345 | if (!old_name || !*old_name) |
| 2346 | return -EINVAL; |
Trond Myklebust | 815d405 | 2011-09-26 20:36:09 -0400 | [diff] [blame] | 2347 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2348 | if (err) |
| 2349 | return err; |
| 2350 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2351 | err = -EINVAL; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2352 | if (mnt_ns_loop(old_path.dentry)) |
David Howells | dd111b3 | 2017-07-04 17:25:09 +0100 | [diff] [blame] | 2353 | goto out; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2354 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2355 | mp = lock_mount(path); |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2356 | if (IS_ERR(mp)) { |
| 2357 | err = PTR_ERR(mp); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2358 | goto out; |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2359 | } |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2360 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2361 | parent = real_mount(path->mnt); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 2362 | if (!check_mnt(parent)) |
| 2363 | goto out2; |
| 2364 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2365 | mnt = __do_loopback(&old_path, recurse); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2366 | if (IS_ERR(mnt)) { |
| 2367 | err = PTR_ERR(mnt); |
Andrey Vagin | e9c5d8a | 2013-04-09 17:33:29 +0400 | [diff] [blame] | 2368 | goto out2; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2369 | } |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2370 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2371 | err = graft_tree(mnt, parent, mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2372 | if (err) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2373 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2374 | umount_tree(mnt, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2375 | unlock_mount_hash(); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 2376 | } |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2377 | out2: |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2378 | unlock_mount(mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2379 | out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2380 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2381 | return err; |
| 2382 | } |
| 2383 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2384 | static struct file *open_detached_copy(struct path *path, bool recursive) |
| 2385 | { |
| 2386 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
| 2387 | struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true); |
| 2388 | struct mount *mnt, *p; |
| 2389 | struct file *file; |
| 2390 | |
| 2391 | if (IS_ERR(ns)) |
| 2392 | return ERR_CAST(ns); |
| 2393 | |
| 2394 | namespace_lock(); |
| 2395 | mnt = __do_loopback(path, recursive); |
| 2396 | if (IS_ERR(mnt)) { |
| 2397 | namespace_unlock(); |
| 2398 | free_mnt_ns(ns); |
| 2399 | return ERR_CAST(mnt); |
| 2400 | } |
| 2401 | |
| 2402 | lock_mount_hash(); |
| 2403 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 2404 | p->mnt_ns = ns; |
| 2405 | ns->mounts++; |
| 2406 | } |
| 2407 | ns->root = mnt; |
| 2408 | list_add_tail(&ns->list, &mnt->mnt_list); |
| 2409 | mntget(&mnt->mnt); |
| 2410 | unlock_mount_hash(); |
| 2411 | namespace_unlock(); |
| 2412 | |
| 2413 | mntput(path->mnt); |
| 2414 | path->mnt = &mnt->mnt; |
| 2415 | file = dentry_open(path, O_PATH, current_cred()); |
| 2416 | if (IS_ERR(file)) |
| 2417 | dissolve_on_fput(path->mnt); |
| 2418 | else |
| 2419 | file->f_mode |= FMODE_NEED_UNMOUNT; |
| 2420 | return file; |
| 2421 | } |
| 2422 | |
Ben Dooks | 2658ce0 | 2019-10-15 11:35:02 +0100 | [diff] [blame] | 2423 | SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags) |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2424 | { |
| 2425 | struct file *file; |
| 2426 | struct path path; |
| 2427 | int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; |
| 2428 | bool detached = flags & OPEN_TREE_CLONE; |
| 2429 | int error; |
| 2430 | int fd; |
| 2431 | |
| 2432 | BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); |
| 2433 | |
| 2434 | if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE | |
| 2435 | AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE | |
| 2436 | OPEN_TREE_CLOEXEC)) |
| 2437 | return -EINVAL; |
| 2438 | |
| 2439 | if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE) |
| 2440 | return -EINVAL; |
| 2441 | |
| 2442 | if (flags & AT_NO_AUTOMOUNT) |
| 2443 | lookup_flags &= ~LOOKUP_AUTOMOUNT; |
| 2444 | if (flags & AT_SYMLINK_NOFOLLOW) |
| 2445 | lookup_flags &= ~LOOKUP_FOLLOW; |
| 2446 | if (flags & AT_EMPTY_PATH) |
| 2447 | lookup_flags |= LOOKUP_EMPTY; |
| 2448 | |
| 2449 | if (detached && !may_mount()) |
| 2450 | return -EPERM; |
| 2451 | |
| 2452 | fd = get_unused_fd_flags(flags & O_CLOEXEC); |
| 2453 | if (fd < 0) |
| 2454 | return fd; |
| 2455 | |
| 2456 | error = user_path_at(dfd, filename, lookup_flags, &path); |
| 2457 | if (unlikely(error)) { |
| 2458 | file = ERR_PTR(error); |
| 2459 | } else { |
| 2460 | if (detached) |
| 2461 | file = open_detached_copy(&path, flags & AT_RECURSIVE); |
| 2462 | else |
| 2463 | file = dentry_open(&path, O_PATH, current_cred()); |
| 2464 | path_put(&path); |
| 2465 | } |
| 2466 | if (IS_ERR(file)) { |
| 2467 | put_unused_fd(fd); |
| 2468 | return PTR_ERR(file); |
| 2469 | } |
| 2470 | fd_install(fd, file); |
| 2471 | return fd; |
| 2472 | } |
| 2473 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2474 | /* |
| 2475 | * Don't allow locked mount flags to be cleared. |
| 2476 | * |
| 2477 | * No locks need to be held here while testing the various MNT_LOCK |
| 2478 | * flags because those flags can never be cleared once they are set. |
| 2479 | */ |
| 2480 | static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2481 | { |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2482 | unsigned int fl = mnt->mnt.mnt_flags; |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2483 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2484 | if ((fl & MNT_LOCK_READONLY) && |
| 2485 | !(mnt_flags & MNT_READONLY)) |
| 2486 | return false; |
| 2487 | |
| 2488 | if ((fl & MNT_LOCK_NODEV) && |
| 2489 | !(mnt_flags & MNT_NODEV)) |
| 2490 | return false; |
| 2491 | |
| 2492 | if ((fl & MNT_LOCK_NOSUID) && |
| 2493 | !(mnt_flags & MNT_NOSUID)) |
| 2494 | return false; |
| 2495 | |
| 2496 | if ((fl & MNT_LOCK_NOEXEC) && |
| 2497 | !(mnt_flags & MNT_NOEXEC)) |
| 2498 | return false; |
| 2499 | |
| 2500 | if ((fl & MNT_LOCK_ATIME) && |
| 2501 | ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) |
| 2502 | return false; |
| 2503 | |
| 2504 | return true; |
| 2505 | } |
| 2506 | |
| 2507 | static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags) |
| 2508 | { |
| 2509 | bool readonly_request = (mnt_flags & MNT_READONLY); |
| 2510 | |
| 2511 | if (readonly_request == __mnt_is_readonly(&mnt->mnt)) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2512 | return 0; |
| 2513 | |
| 2514 | if (readonly_request) |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2515 | return mnt_make_readonly(mnt); |
| 2516 | |
| 2517 | return __mnt_unmake_readonly(mnt); |
| 2518 | } |
| 2519 | |
| 2520 | /* |
| 2521 | * Update the user-settable attributes on a mount. The caller must hold |
| 2522 | * sb->s_umount for writing. |
| 2523 | */ |
| 2524 | static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) |
| 2525 | { |
| 2526 | lock_mount_hash(); |
| 2527 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
| 2528 | mnt->mnt.mnt_flags = mnt_flags; |
| 2529 | touch_mnt_namespace(mnt->mnt_ns); |
| 2530 | unlock_mount_hash(); |
| 2531 | } |
| 2532 | |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2533 | static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt) |
| 2534 | { |
| 2535 | struct super_block *sb = mnt->mnt_sb; |
| 2536 | |
| 2537 | if (!__mnt_is_readonly(mnt) && |
| 2538 | (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { |
| 2539 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
| 2540 | char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM); |
| 2541 | struct tm tm; |
| 2542 | |
| 2543 | time64_to_tm(sb->s_time_max, 0, &tm); |
| 2544 | |
Eric Biggers | 0ecee66 | 2019-10-16 19:48:14 -0700 | [diff] [blame] | 2545 | pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n", |
| 2546 | sb->s_type->name, |
| 2547 | is_mounted(mnt) ? "remounted" : "mounted", |
| 2548 | mntpath, |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2549 | tm.tm_year+1900, (unsigned long long)sb->s_time_max); |
| 2550 | |
| 2551 | free_page((unsigned long)buf); |
| 2552 | } |
| 2553 | } |
| 2554 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2555 | /* |
| 2556 | * Handle reconfiguration of the mountpoint only without alteration of the |
| 2557 | * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND |
| 2558 | * to mount(2). |
| 2559 | */ |
| 2560 | static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags) |
| 2561 | { |
| 2562 | struct super_block *sb = path->mnt->mnt_sb; |
| 2563 | struct mount *mnt = real_mount(path->mnt); |
| 2564 | int ret; |
| 2565 | |
| 2566 | if (!check_mnt(mnt)) |
| 2567 | return -EINVAL; |
| 2568 | |
| 2569 | if (path->dentry != mnt->mnt.mnt_root) |
| 2570 | return -EINVAL; |
| 2571 | |
| 2572 | if (!can_change_locked_flags(mnt, mnt_flags)) |
| 2573 | return -EPERM; |
| 2574 | |
| 2575 | down_write(&sb->s_umount); |
| 2576 | ret = change_mount_ro_state(mnt, mnt_flags); |
| 2577 | if (ret == 0) |
| 2578 | set_mount_attributes(mnt, mnt_flags); |
| 2579 | up_write(&sb->s_umount); |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2580 | |
| 2581 | mnt_warn_timestamp_expiry(path, &mnt->mnt); |
| 2582 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2583 | return ret; |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2584 | } |
| 2585 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2586 | /* |
| 2587 | * change filesystem flags. dir should be a physical root of filesystem. |
| 2588 | * If you've mounted a non-root directory somewhere and want to do remount |
| 2589 | * on it - tough luck. |
| 2590 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2591 | static int do_remount(struct path *path, int ms_flags, int sb_flags, |
| 2592 | int mnt_flags, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2593 | { |
| 2594 | int err; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2595 | struct super_block *sb = path->mnt->mnt_sb; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2596 | struct mount *mnt = real_mount(path->mnt); |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2597 | struct fs_context *fc; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2598 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2599 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2600 | return -EINVAL; |
| 2601 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2602 | if (path->dentry != path->mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2603 | return -EINVAL; |
| 2604 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2605 | if (!can_change_locked_flags(mnt, mnt_flags)) |
Eric W. Biederman | 07b6455 | 2014-07-28 17:10:56 -0700 | [diff] [blame] | 2606 | return -EPERM; |
Eric W. Biederman | 9566d67 | 2014-07-28 17:26:07 -0700 | [diff] [blame] | 2607 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2608 | fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK); |
| 2609 | if (IS_ERR(fc)) |
| 2610 | return PTR_ERR(fc); |
Eric Paris | ff36fe2 | 2011-03-03 16:09:14 -0500 | [diff] [blame] | 2611 | |
Miklos Szeredi | b330966 | 2020-07-14 14:45:41 +0200 | [diff] [blame] | 2612 | fc->oldapi = true; |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2613 | err = parse_monolithic_mount_data(fc, data); |
| 2614 | if (!err) { |
| 2615 | down_write(&sb->s_umount); |
| 2616 | err = -EPERM; |
| 2617 | if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { |
| 2618 | err = reconfigure_super(fc); |
| 2619 | if (!err) |
| 2620 | set_mount_attributes(mnt, mnt_flags); |
| 2621 | } |
| 2622 | up_write(&sb->s_umount); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 2623 | } |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2624 | |
| 2625 | mnt_warn_timestamp_expiry(path, &mnt->mnt); |
| 2626 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2627 | put_fs_context(fc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2628 | return err; |
| 2629 | } |
| 2630 | |
Al Viro | cbbe362 | 2011-11-24 20:01:19 -0500 | [diff] [blame] | 2631 | static inline int tree_contains_unbindable(struct mount *mnt) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2632 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2633 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2634 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2635 | if (IS_MNT_UNBINDABLE(p)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2636 | return 1; |
| 2637 | } |
| 2638 | return 0; |
| 2639 | } |
| 2640 | |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2641 | /* |
| 2642 | * Check that there aren't references to earlier/same mount namespaces in the |
| 2643 | * specified subtree. Such references can act as pins for mount namespaces |
| 2644 | * that aren't checked by the mount-cycle checking code, thereby allowing |
| 2645 | * cycles to be made. |
| 2646 | */ |
| 2647 | static bool check_for_nsfs_mounts(struct mount *subtree) |
| 2648 | { |
| 2649 | struct mount *p; |
| 2650 | bool ret = false; |
| 2651 | |
| 2652 | lock_mount_hash(); |
| 2653 | for (p = subtree; p; p = next_mnt(p, subtree)) |
| 2654 | if (mnt_ns_loop(p->mnt.mnt_root)) |
| 2655 | goto out; |
| 2656 | |
| 2657 | ret = true; |
| 2658 | out: |
| 2659 | unlock_mount_hash(); |
| 2660 | return ret; |
| 2661 | } |
| 2662 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2663 | static int do_move_mount(struct path *old_path, struct path *new_path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2664 | { |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2665 | struct mnt_namespace *ns; |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2666 | struct mount *p; |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2667 | struct mount *old; |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2668 | struct mount *parent; |
| 2669 | struct mountpoint *mp, *old_mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2670 | int err; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2671 | bool attached; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2672 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2673 | mp = lock_mount(new_path); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2674 | if (IS_ERR(mp)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2675 | return PTR_ERR(mp); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 2676 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2677 | old = real_mount(old_path->mnt); |
| 2678 | p = real_mount(new_path->mnt); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2679 | parent = old->mnt_parent; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2680 | attached = mnt_has_parent(old); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2681 | old_mp = old->mnt_mp; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2682 | ns = old->mnt_ns; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2683 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2684 | err = -EINVAL; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2685 | /* The mountpoint must be in our namespace. */ |
| 2686 | if (!check_mnt(p)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2687 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2688 | |
Eric Biggers | 570d7a9 | 2019-06-29 13:27:44 -0700 | [diff] [blame] | 2689 | /* The thing moved must be mounted... */ |
| 2690 | if (!is_mounted(&old->mnt)) |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2691 | goto out; |
| 2692 | |
Eric Biggers | 570d7a9 | 2019-06-29 13:27:44 -0700 | [diff] [blame] | 2693 | /* ... and either ours or the root of anon namespace */ |
| 2694 | if (!(attached ? check_mnt(old) : is_anon_ns(ns))) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2695 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2696 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2697 | if (old->mnt.mnt_flags & MNT_LOCKED) |
| 2698 | goto out; |
| 2699 | |
| 2700 | if (old_path->dentry != old_path->mnt->mnt_root) |
| 2701 | goto out; |
| 2702 | |
| 2703 | if (d_is_dir(new_path->dentry) != |
| 2704 | d_is_dir(old_path->dentry)) |
| 2705 | goto out; |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2706 | /* |
| 2707 | * Don't move a mount residing in a shared parent. |
| 2708 | */ |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2709 | if (attached && IS_MNT_SHARED(parent)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2710 | goto out; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2711 | /* |
| 2712 | * Don't move a mount tree containing unbindable mounts to a destination |
| 2713 | * mount which is shared. |
| 2714 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2715 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2716 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2717 | err = -ELOOP; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2718 | if (!check_for_nsfs_mounts(old)) |
| 2719 | goto out; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2720 | for (; mnt_has_parent(p); p = p->mnt_parent) |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2721 | if (p == old) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2722 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2723 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2724 | err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2725 | attached); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2726 | if (err) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2727 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2728 | |
| 2729 | /* if the mount is moved, it should no longer be expire |
| 2730 | * automatically */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2731 | list_del_init(&old->mnt_expire); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2732 | if (attached) |
| 2733 | put_mountpoint(old_mp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2734 | out: |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2735 | unlock_mount(mp); |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2736 | if (!err) { |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2737 | if (attached) |
| 2738 | mntput_no_expire(parent); |
| 2739 | else |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2740 | free_mnt_ns(ns); |
| 2741 | } |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2742 | return err; |
| 2743 | } |
| 2744 | |
| 2745 | static int do_move_mount_old(struct path *path, const char *old_name) |
| 2746 | { |
| 2747 | struct path old_path; |
| 2748 | int err; |
| 2749 | |
| 2750 | if (!old_name || !*old_name) |
| 2751 | return -EINVAL; |
| 2752 | |
| 2753 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
| 2754 | if (err) |
| 2755 | return err; |
| 2756 | |
| 2757 | err = do_move_mount(&old_path, path); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2758 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2759 | return err; |
| 2760 | } |
| 2761 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2762 | /* |
| 2763 | * add a mount into a namespace's mount tree |
| 2764 | */ |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2765 | static int do_add_mount(struct mount *newmnt, struct mountpoint *mp, |
| 2766 | struct path *path, int mnt_flags) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2767 | { |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2768 | struct mount *parent = real_mount(path->mnt); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2769 | |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2770 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2771 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2772 | if (unlikely(!check_mnt(parent))) { |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 2773 | /* that's acceptable only for automounts done in private ns */ |
| 2774 | if (!(mnt_flags & MNT_SHRINKABLE)) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2775 | return -EINVAL; |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 2776 | /* ... and for those we'd better have mountpoint still alive */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2777 | if (!parent->mnt_ns) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2778 | return -EINVAL; |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 2779 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2780 | |
| 2781 | /* Refuse the same filesystem on the same mount point */ |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2782 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2783 | path->mnt->mnt_root == path->dentry) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2784 | return -EBUSY; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2785 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2786 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2787 | return -EINVAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2788 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 2789 | newmnt->mnt.mnt_flags = mnt_flags; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2790 | return graft_tree(newmnt, parent, mp); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2791 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2792 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 2793 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags); |
| 2794 | |
| 2795 | /* |
| 2796 | * Create a new mount using a superblock configuration and request it |
| 2797 | * be added to the namespace tree. |
| 2798 | */ |
| 2799 | static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, |
| 2800 | unsigned int mnt_flags) |
| 2801 | { |
| 2802 | struct vfsmount *mnt; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2803 | struct mountpoint *mp; |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 2804 | struct super_block *sb = fc->root->d_sb; |
| 2805 | int error; |
| 2806 | |
Al Viro | c9ce29e | 2018-12-20 15:04:50 -0500 | [diff] [blame] | 2807 | error = security_sb_kern_mount(sb); |
| 2808 | if (!error && mount_too_revealing(sb, &mnt_flags)) |
| 2809 | error = -EPERM; |
| 2810 | |
| 2811 | if (unlikely(error)) { |
| 2812 | fc_drop_locked(fc); |
| 2813 | return error; |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 2814 | } |
| 2815 | |
| 2816 | up_write(&sb->s_umount); |
| 2817 | |
| 2818 | mnt = vfs_create_mount(fc); |
| 2819 | if (IS_ERR(mnt)) |
| 2820 | return PTR_ERR(mnt); |
| 2821 | |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2822 | mnt_warn_timestamp_expiry(mountpoint, mnt); |
| 2823 | |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2824 | mp = lock_mount(mountpoint); |
| 2825 | if (IS_ERR(mp)) { |
| 2826 | mntput(mnt); |
| 2827 | return PTR_ERR(mp); |
| 2828 | } |
| 2829 | error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags); |
| 2830 | unlock_mount(mp); |
Eric Biggers | 0ecee66 | 2019-10-16 19:48:14 -0700 | [diff] [blame] | 2831 | if (error < 0) |
| 2832 | mntput(mnt); |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 2833 | return error; |
| 2834 | } |
Eric W. Biederman | 1b852bc | 2015-05-08 23:22:29 -0500 | [diff] [blame] | 2835 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2836 | /* |
| 2837 | * create a new mount for userspace and request it to be added into the |
| 2838 | * namespace's tree |
| 2839 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2840 | static int do_new_mount(struct path *path, const char *fstype, int sb_flags, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2841 | int mnt_flags, const char *name, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2842 | { |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2843 | struct file_system_type *type; |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2844 | struct fs_context *fc; |
| 2845 | const char *subtype = NULL; |
| 2846 | int err = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2847 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2848 | if (!fstype) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2849 | return -EINVAL; |
| 2850 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2851 | type = get_fs_type(fstype); |
| 2852 | if (!type) |
| 2853 | return -ENODEV; |
| 2854 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2855 | if (type->fs_flags & FS_HAS_SUBTYPE) { |
| 2856 | subtype = strchr(fstype, '.'); |
| 2857 | if (subtype) { |
| 2858 | subtype++; |
| 2859 | if (!*subtype) { |
| 2860 | put_filesystem(type); |
| 2861 | return -EINVAL; |
| 2862 | } |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2863 | } |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 2864 | } |
| 2865 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2866 | fc = fs_context_for_mount(type, sb_flags); |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 2867 | put_filesystem(type); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2868 | if (IS_ERR(fc)) |
| 2869 | return PTR_ERR(fc); |
| 2870 | |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2871 | if (subtype) |
| 2872 | err = vfs_parse_fs_string(fc, "subtype", |
| 2873 | subtype, strlen(subtype)); |
| 2874 | if (!err && name) |
| 2875 | err = vfs_parse_fs_string(fc, "source", name, strlen(name)); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2876 | if (!err) |
| 2877 | err = parse_monolithic_mount_data(fc, data); |
Al Viro | c3aabf0 | 2019-05-13 12:57:22 -0400 | [diff] [blame] | 2878 | if (!err && !mount_capable(fc)) |
| 2879 | err = -EPERM; |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2880 | if (!err) |
| 2881 | err = vfs_get_tree(fc); |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 2882 | if (!err) |
| 2883 | err = do_new_mount_fc(fc, path, mnt_flags); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2884 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 2885 | put_fs_context(fc); |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 2886 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2887 | } |
| 2888 | |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2889 | int finish_automount(struct vfsmount *m, struct path *path) |
| 2890 | { |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2891 | struct dentry *dentry = path->dentry; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2892 | struct mountpoint *mp; |
Al Viro | 25e195a | 2020-01-11 11:27:46 -0500 | [diff] [blame] | 2893 | struct mount *mnt; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2894 | int err; |
Al Viro | 25e195a | 2020-01-11 11:27:46 -0500 | [diff] [blame] | 2895 | |
| 2896 | if (!m) |
| 2897 | return 0; |
| 2898 | if (IS_ERR(m)) |
| 2899 | return PTR_ERR(m); |
| 2900 | |
| 2901 | mnt = real_mount(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2902 | /* The new mount record should have at least 2 refs to prevent it being |
| 2903 | * expired before we get a chance to add it |
| 2904 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2905 | BUG_ON(mnt_get_count(mnt) < 2); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2906 | |
| 2907 | if (m->mnt_sb == path->mnt->mnt_sb && |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2908 | m->mnt_root == dentry) { |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2909 | err = -ELOOP; |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2910 | goto discard; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2911 | } |
| 2912 | |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2913 | /* |
| 2914 | * we don't want to use lock_mount() - in this case finding something |
| 2915 | * that overmounts our mountpoint to be means "quitely drop what we've |
| 2916 | * got", not "try to mount it on top". |
| 2917 | */ |
| 2918 | inode_lock(dentry->d_inode); |
| 2919 | namespace_lock(); |
| 2920 | if (unlikely(cant_mount(dentry))) { |
| 2921 | err = -ENOENT; |
| 2922 | goto discard_locked; |
| 2923 | } |
| 2924 | rcu_read_lock(); |
| 2925 | if (unlikely(__lookup_mnt(path->mnt, dentry))) { |
| 2926 | rcu_read_unlock(); |
| 2927 | err = 0; |
| 2928 | goto discard_locked; |
| 2929 | } |
| 2930 | rcu_read_unlock(); |
| 2931 | mp = get_mountpoint(dentry); |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2932 | if (IS_ERR(mp)) { |
| 2933 | err = PTR_ERR(mp); |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2934 | goto discard_locked; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2935 | } |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2936 | |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 2937 | err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
| 2938 | unlock_mount(mp); |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 2939 | if (unlikely(err)) |
| 2940 | goto discard; |
| 2941 | mntput(m); |
| 2942 | return 0; |
| 2943 | |
| 2944 | discard_locked: |
| 2945 | namespace_unlock(); |
| 2946 | inode_unlock(dentry->d_inode); |
| 2947 | discard: |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2948 | /* remove m from any expiration list it may be on */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2949 | if (!list_empty(&mnt->mnt_expire)) { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2950 | namespace_lock(); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2951 | list_del_init(&mnt->mnt_expire); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2952 | namespace_unlock(); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2953 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 2954 | mntput(m); |
| 2955 | mntput(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 2956 | return err; |
| 2957 | } |
| 2958 | |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2959 | /** |
| 2960 | * mnt_set_expiry - Put a mount on an expiration list |
| 2961 | * @mnt: The mount to list. |
| 2962 | * @expiry_list: The list to add the mount to. |
| 2963 | */ |
| 2964 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) |
| 2965 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2966 | namespace_lock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2967 | |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2968 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2969 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2970 | namespace_unlock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 2971 | } |
| 2972 | EXPORT_SYMBOL(mnt_set_expiry); |
| 2973 | |
| 2974 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2975 | * process a list of expirable mountpoints with the intent of discarding any |
| 2976 | * mountpoints that aren't in use and haven't been touched since last we came |
| 2977 | * here |
| 2978 | */ |
| 2979 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 2980 | { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2981 | struct mount *mnt, *next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2982 | LIST_HEAD(graveyard); |
| 2983 | |
| 2984 | if (list_empty(mounts)) |
| 2985 | return; |
| 2986 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2987 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2988 | lock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2989 | |
| 2990 | /* extract from the expiration list every vfsmount that matches the |
| 2991 | * following criteria: |
| 2992 | * - only referenced by its parent vfsmount |
| 2993 | * - still marked for expiry (marked on the last call here; marks are |
| 2994 | * cleared by mntput()) |
| 2995 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2996 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 2997 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 2998 | propagate_mount_busy(mnt, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2999 | continue; |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3000 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3001 | } |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3002 | while (!list_empty(&graveyard)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3003 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3004 | touch_mnt_namespace(mnt->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 3005 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3006 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3007 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 3008 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3009 | } |
| 3010 | |
| 3011 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 3012 | |
| 3013 | /* |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3014 | * Ripoff of 'select_parent()' |
| 3015 | * |
| 3016 | * search the list of submounts for a given mountpoint, and move any |
| 3017 | * shrinkable submounts to the 'graveyard' list. |
| 3018 | */ |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3019 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3020 | { |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3021 | struct mount *this_parent = parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3022 | struct list_head *next; |
| 3023 | int found = 0; |
| 3024 | |
| 3025 | repeat: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3026 | next = this_parent->mnt_mounts.next; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3027 | resume: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3028 | while (next != &this_parent->mnt_mounts) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3029 | struct list_head *tmp = next; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3030 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3031 | |
| 3032 | next = tmp->next; |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3033 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3034 | continue; |
| 3035 | /* |
| 3036 | * Descend a level if the d_mounts list is non-empty. |
| 3037 | */ |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3038 | if (!list_empty(&mnt->mnt_mounts)) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3039 | this_parent = mnt; |
| 3040 | goto repeat; |
| 3041 | } |
| 3042 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 3043 | if (!propagate_mount_busy(mnt, 1)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3044 | list_move_tail(&mnt->mnt_expire, graveyard); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3045 | found++; |
| 3046 | } |
| 3047 | } |
| 3048 | /* |
| 3049 | * All done at this level ... ascend and resume the search |
| 3050 | */ |
| 3051 | if (this_parent != parent) { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3052 | next = this_parent->mnt_child.next; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 3053 | this_parent = this_parent->mnt_parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3054 | goto resume; |
| 3055 | } |
| 3056 | return found; |
| 3057 | } |
| 3058 | |
| 3059 | /* |
| 3060 | * process a list of expirable mountpoints with the intent of discarding any |
| 3061 | * submounts of a specific parent mountpoint |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 3062 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3063 | * mount_lock must be held for write |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3064 | */ |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 3065 | static void shrink_submounts(struct mount *mnt) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3066 | { |
| 3067 | LIST_HEAD(graveyard); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 3068 | struct mount *m; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3069 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3070 | /* extract submounts of 'mountpoint' from the expiration list */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 3071 | while (select_submounts(mnt, &graveyard)) { |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3072 | while (!list_empty(&graveyard)) { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 3073 | m = list_first_entry(&graveyard, struct mount, |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3074 | mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3075 | touch_mnt_namespace(m->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 3076 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3077 | } |
| 3078 | } |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3079 | } |
| 3080 | |
Christoph Hellwig | 028abd9 | 2020-09-17 10:22:34 +0200 | [diff] [blame] | 3081 | static void *copy_mount_options(const void __user * data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3082 | { |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3083 | char *copy; |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3084 | unsigned left, offset; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 3085 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3086 | if (!data) |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3087 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3088 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3089 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| 3090 | if (!copy) |
| 3091 | return ERR_PTR(-ENOMEM); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3092 | |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3093 | left = copy_from_user(copy, data, PAGE_SIZE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3094 | |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3095 | /* |
| 3096 | * Not all architectures have an exact copy_from_user(). Resort to |
| 3097 | * byte at a time. |
| 3098 | */ |
| 3099 | offset = PAGE_SIZE - left; |
| 3100 | while (left) { |
| 3101 | char c; |
| 3102 | if (get_user(c, (const char __user *)data + offset)) |
| 3103 | break; |
| 3104 | copy[offset] = c; |
| 3105 | left--; |
| 3106 | offset++; |
| 3107 | } |
| 3108 | |
| 3109 | if (left == PAGE_SIZE) { |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3110 | kfree(copy); |
| 3111 | return ERR_PTR(-EFAULT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3112 | } |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3113 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3114 | return copy; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3115 | } |
| 3116 | |
Christoph Hellwig | 028abd9 | 2020-09-17 10:22:34 +0200 | [diff] [blame] | 3117 | static char *copy_mount_string(const void __user *data) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3118 | { |
Chandan Rajendra | fbdb440 | 2019-01-22 12:21:52 +0530 | [diff] [blame] | 3119 | return data ? strndup_user(data, PATH_MAX) : NULL; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3120 | } |
| 3121 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3122 | /* |
| 3123 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 3124 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 3125 | * |
| 3126 | * data is a (void *) that can point to any structure up to |
| 3127 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 3128 | * information (or be NULL). |
| 3129 | * |
| 3130 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 3131 | * When the flags word was introduced its top half was required |
| 3132 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 3133 | * Therefore, if this magic number is present, it carries no information |
| 3134 | * and must be discarded. |
| 3135 | */ |
Christoph Hellwig | c60166f | 2020-07-21 11:12:08 +0200 | [diff] [blame] | 3136 | int path_mount(const char *dev_name, struct path *path, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 3137 | const char *type_page, unsigned long flags, void *data_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3138 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3139 | unsigned int mnt_flags = 0, sb_flags; |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3140 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3141 | |
| 3142 | /* Discard magic */ |
| 3143 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 3144 | flags &= ~MS_MGC_MSK; |
| 3145 | |
| 3146 | /* Basic sanity checks */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3147 | if (data_page) |
| 3148 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 3149 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3150 | if (flags & MS_NOUSER) |
| 3151 | return -EINVAL; |
| 3152 | |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3153 | ret = security_sb_mount(dev_name, path, type_page, flags, data_page); |
| 3154 | if (ret) |
| 3155 | return ret; |
| 3156 | if (!may_mount()) |
| 3157 | return -EPERM; |
| 3158 | if ((flags & SB_MANDLOCK) && !may_mandlock()) |
| 3159 | return -EPERM; |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 3160 | |
Andi Kleen | 613cbe3 | 2009-04-19 18:40:43 +0200 | [diff] [blame] | 3161 | /* Default to relatime unless overriden */ |
| 3162 | if (!(flags & MS_NOATIME)) |
| 3163 | mnt_flags |= MNT_RELATIME; |
Matthew Garrett | 0a1c01c | 2009-03-26 17:53:14 +0000 | [diff] [blame] | 3164 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3165 | /* Separate the per-mountpoint flags */ |
| 3166 | if (flags & MS_NOSUID) |
| 3167 | mnt_flags |= MNT_NOSUID; |
| 3168 | if (flags & MS_NODEV) |
| 3169 | mnt_flags |= MNT_NODEV; |
| 3170 | if (flags & MS_NOEXEC) |
| 3171 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 3172 | if (flags & MS_NOATIME) |
| 3173 | mnt_flags |= MNT_NOATIME; |
| 3174 | if (flags & MS_NODIRATIME) |
| 3175 | mnt_flags |= MNT_NODIRATIME; |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 3176 | if (flags & MS_STRICTATIME) |
| 3177 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
David Howells | a9e5b73 | 2018-04-20 13:35:02 +0100 | [diff] [blame] | 3178 | if (flags & MS_RDONLY) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 3179 | mnt_flags |= MNT_READONLY; |
Mattias Nissler | dab741e0 | 2020-08-27 11:09:46 -0600 | [diff] [blame] | 3180 | if (flags & MS_NOSYMFOLLOW) |
| 3181 | mnt_flags |= MNT_NOSYMFOLLOW; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 3182 | |
Eric W. Biederman | ffbc6f0 | 2014-07-28 17:36:04 -0700 | [diff] [blame] | 3183 | /* The default atime for remount is preservation */ |
| 3184 | if ((flags & MS_REMOUNT) && |
| 3185 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | |
| 3186 | MS_STRICTATIME)) == 0)) { |
| 3187 | mnt_flags &= ~MNT_ATIME_MASK; |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3188 | mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; |
Eric W. Biederman | ffbc6f0 | 2014-07-28 17:36:04 -0700 | [diff] [blame] | 3189 | } |
| 3190 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3191 | sb_flags = flags & (SB_RDONLY | |
| 3192 | SB_SYNCHRONOUS | |
| 3193 | SB_MANDLOCK | |
| 3194 | SB_DIRSYNC | |
| 3195 | SB_SILENT | |
Mimi Zohar | 917086f | 2017-10-08 00:28:21 -0400 | [diff] [blame] | 3196 | SB_POSIXACL | |
Markus Trippelsdorf | d7ee946 | 2017-10-11 07:01:31 +0200 | [diff] [blame] | 3197 | SB_LAZYTIME | |
Mimi Zohar | 917086f | 2017-10-08 00:28:21 -0400 | [diff] [blame] | 3198 | SB_I_VERSION); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3199 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 3200 | if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3201 | return do_reconfigure_mnt(path, mnt_flags); |
| 3202 | if (flags & MS_REMOUNT) |
| 3203 | return do_remount(path, flags, sb_flags, mnt_flags, data_page); |
| 3204 | if (flags & MS_BIND) |
| 3205 | return do_loopback(path, dev_name, flags & MS_REC); |
| 3206 | if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 3207 | return do_change_type(path, flags); |
| 3208 | if (flags & MS_MOVE) |
| 3209 | return do_move_mount_old(path, dev_name); |
| 3210 | |
| 3211 | return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, |
| 3212 | data_page); |
| 3213 | } |
| 3214 | |
| 3215 | long do_mount(const char *dev_name, const char __user *dir_name, |
| 3216 | const char *type_page, unsigned long flags, void *data_page) |
| 3217 | { |
| 3218 | struct path path; |
| 3219 | int ret; |
| 3220 | |
| 3221 | ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); |
| 3222 | if (ret) |
| 3223 | return ret; |
| 3224 | ret = path_mount(dev_name, &path, type_page, flags, data_page); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 3225 | path_put(&path); |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3226 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3227 | } |
| 3228 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3229 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
| 3230 | { |
| 3231 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); |
| 3232 | } |
| 3233 | |
| 3234 | static void dec_mnt_namespaces(struct ucounts *ucounts) |
| 3235 | { |
| 3236 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); |
| 3237 | } |
| 3238 | |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3239 | static void free_mnt_ns(struct mnt_namespace *ns) |
| 3240 | { |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3241 | if (!is_anon_ns(ns)) |
| 3242 | ns_free_inum(&ns->ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3243 | dec_mnt_namespaces(ns->ucounts); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3244 | put_user_ns(ns->user_ns); |
| 3245 | kfree(ns); |
| 3246 | } |
| 3247 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3248 | /* |
| 3249 | * Assign a sequence number so we can detect when we attempt to bind |
| 3250 | * mount a reference to an older mount namespace into the current |
| 3251 | * mount namespace, preventing reference counting loops. A 64bit |
| 3252 | * number incrementing at 10Ghz will take 12,427 years to wrap which |
| 3253 | * is effectively never, so we can ignore the possibility. |
| 3254 | */ |
| 3255 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); |
| 3256 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3257 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3258 | { |
| 3259 | struct mnt_namespace *new_ns; |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3260 | struct ucounts *ucounts; |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 3261 | int ret; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3262 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3263 | ucounts = inc_mnt_namespaces(user_ns); |
| 3264 | if (!ucounts) |
Eric W. Biederman | df75e77 | 2016-09-22 13:08:36 -0500 | [diff] [blame] | 3265 | return ERR_PTR(-ENOSPC); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3266 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3267 | new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3268 | if (!new_ns) { |
| 3269 | dec_mnt_namespaces(ucounts); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3270 | return ERR_PTR(-ENOMEM); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3271 | } |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3272 | if (!anon) { |
| 3273 | ret = ns_alloc_inum(&new_ns->ns); |
| 3274 | if (ret) { |
| 3275 | kfree(new_ns); |
| 3276 | dec_mnt_namespaces(ucounts); |
| 3277 | return ERR_PTR(ret); |
| 3278 | } |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 3279 | } |
Al Viro | 33c4294 | 2014-11-01 02:32:53 -0400 | [diff] [blame] | 3280 | new_ns->ns.ops = &mntns_operations; |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3281 | if (!anon) |
| 3282 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
Kirill Tkhai | 1a7b8969 | 2020-08-03 13:16:42 +0300 | [diff] [blame] | 3283 | refcount_set(&new_ns->ns.count, 1); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3284 | INIT_LIST_HEAD(&new_ns->list); |
| 3285 | init_waitqueue_head(&new_ns->poll); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 3286 | spin_lock_init(&new_ns->ns_lock); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3287 | new_ns->user_ns = get_user_ns(user_ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3288 | new_ns->ucounts = ucounts; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3289 | return new_ns; |
| 3290 | } |
| 3291 | |
Emese Revfy | 0766f78 | 2016-06-20 20:42:34 +0200 | [diff] [blame] | 3292 | __latent_entropy |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3293 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
| 3294 | struct user_namespace *user_ns, struct fs_struct *new_fs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3295 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3296 | struct mnt_namespace *new_ns; |
Al Viro | 7f2da1e | 2008-05-10 20:44:54 -0400 | [diff] [blame] | 3297 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3298 | struct mount *p, *q; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3299 | struct mount *old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 3300 | struct mount *new; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 3301 | int copy_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3302 | |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3303 | BUG_ON(!ns); |
| 3304 | |
| 3305 | if (likely(!(flags & CLONE_NEWNS))) { |
| 3306 | get_mnt_ns(ns); |
| 3307 | return ns; |
| 3308 | } |
| 3309 | |
| 3310 | old = ns->root; |
| 3311 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3312 | new_ns = alloc_mnt_ns(user_ns, false); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3313 | if (IS_ERR(new_ns)) |
| 3314 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3315 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3316 | namespace_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3317 | /* First pass: copy the tree topology */ |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 3318 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3319 | if (user_ns != ns->user_ns) |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 3320 | copy_flags |= CL_SHARED_TO_SLAVE; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 3321 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 3322 | if (IS_ERR(new)) { |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 3323 | namespace_unlock(); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3324 | free_mnt_ns(new_ns); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 3325 | return ERR_CAST(new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3326 | } |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 3327 | if (user_ns != ns->user_ns) { |
| 3328 | lock_mount_hash(); |
| 3329 | lock_mnt_tree(new); |
| 3330 | unlock_mount_hash(); |
| 3331 | } |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 3332 | new_ns->root = new; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 3333 | list_add_tail(&new_ns->list, &new->mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3334 | |
| 3335 | /* |
| 3336 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 3337 | * as belonging to new namespace. We have already acquired a private |
| 3338 | * fs_struct, so tsk->fs->lock is not needed. |
| 3339 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 3340 | p = old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 3341 | q = new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3342 | while (p) { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3343 | q->mnt_ns = new_ns; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 3344 | new_ns->mounts++; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3345 | if (new_fs) { |
| 3346 | if (&p->mnt == new_fs->root.mnt) { |
| 3347 | new_fs->root.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3348 | rootmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3349 | } |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3350 | if (&p->mnt == new_fs->pwd.mnt) { |
| 3351 | new_fs->pwd.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3352 | pwdmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3353 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3354 | } |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 3355 | p = next_mnt(p, old); |
| 3356 | q = next_mnt(q, new); |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 3357 | if (!q) |
| 3358 | break; |
| 3359 | while (p->mnt.mnt_root != q->mnt.mnt_root) |
| 3360 | p = next_mnt(p, old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3361 | } |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 3362 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3363 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3364 | if (rootmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 3365 | mntput(rootmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3366 | if (pwdmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 3367 | mntput(pwdmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3368 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 3369 | return new_ns; |
| 3370 | } |
| 3371 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3372 | struct dentry *mount_subtree(struct vfsmount *m, const char *name) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3373 | { |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3374 | struct mount *mnt = real_mount(m); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3375 | struct mnt_namespace *ns; |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3376 | struct super_block *s; |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3377 | struct path path; |
| 3378 | int err; |
| 3379 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3380 | ns = alloc_mnt_ns(&init_user_ns, true); |
| 3381 | if (IS_ERR(ns)) { |
| 3382 | mntput(m); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3383 | return ERR_CAST(ns); |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3384 | } |
| 3385 | mnt->mnt_ns = ns; |
| 3386 | ns->root = mnt; |
| 3387 | ns->mounts++; |
| 3388 | list_add(&mnt->mnt_list, &ns->list); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3389 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3390 | err = vfs_path_lookup(m->mnt_root, m, |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3391 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
| 3392 | |
| 3393 | put_mnt_ns(ns); |
| 3394 | |
| 3395 | if (err) |
| 3396 | return ERR_PTR(err); |
| 3397 | |
| 3398 | /* trade a vfsmount reference for active sb one */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3399 | s = path.mnt->mnt_sb; |
| 3400 | atomic_inc(&s->s_active); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3401 | mntput(path.mnt); |
| 3402 | /* lock the sucker */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3403 | down_write(&s->s_umount); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3404 | /* ... and return the root of (sub)tree on it */ |
| 3405 | return path.dentry; |
| 3406 | } |
| 3407 | EXPORT_SYMBOL(mount_subtree); |
| 3408 | |
Dominik Brodowski | cccaa5e | 2018-10-23 22:41:09 +0200 | [diff] [blame] | 3409 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 3410 | char __user *, type, unsigned long, flags, void __user *, data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3411 | { |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3412 | int ret; |
| 3413 | char *kernel_type; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3414 | char *kernel_dev; |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3415 | void *options; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3416 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3417 | kernel_type = copy_mount_string(type); |
| 3418 | ret = PTR_ERR(kernel_type); |
| 3419 | if (IS_ERR(kernel_type)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3420 | goto out_type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3421 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3422 | kernel_dev = copy_mount_string(dev_name); |
| 3423 | ret = PTR_ERR(kernel_dev); |
| 3424 | if (IS_ERR(kernel_dev)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3425 | goto out_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3426 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3427 | options = copy_mount_options(data); |
| 3428 | ret = PTR_ERR(options); |
| 3429 | if (IS_ERR(options)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3430 | goto out_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3431 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3432 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3433 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3434 | kfree(options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3435 | out_data: |
| 3436 | kfree(kernel_dev); |
| 3437 | out_dev: |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3438 | kfree(kernel_type); |
| 3439 | out_type: |
| 3440 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3441 | } |
| 3442 | |
| 3443 | /* |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3444 | * Create a kernel mount representation for a new, prepared superblock |
| 3445 | * (specified by fs_fd) and attach to an open_tree-like file descriptor. |
| 3446 | */ |
| 3447 | SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, |
| 3448 | unsigned int, attr_flags) |
| 3449 | { |
| 3450 | struct mnt_namespace *ns; |
| 3451 | struct fs_context *fc; |
| 3452 | struct file *file; |
| 3453 | struct path newmount; |
| 3454 | struct mount *mnt; |
| 3455 | struct fd f; |
| 3456 | unsigned int mnt_flags = 0; |
| 3457 | long ret; |
| 3458 | |
| 3459 | if (!may_mount()) |
| 3460 | return -EPERM; |
| 3461 | |
| 3462 | if ((flags & ~(FSMOUNT_CLOEXEC)) != 0) |
| 3463 | return -EINVAL; |
| 3464 | |
| 3465 | if (attr_flags & ~(MOUNT_ATTR_RDONLY | |
| 3466 | MOUNT_ATTR_NOSUID | |
| 3467 | MOUNT_ATTR_NODEV | |
| 3468 | MOUNT_ATTR_NOEXEC | |
| 3469 | MOUNT_ATTR__ATIME | |
| 3470 | MOUNT_ATTR_NODIRATIME)) |
| 3471 | return -EINVAL; |
| 3472 | |
| 3473 | if (attr_flags & MOUNT_ATTR_RDONLY) |
| 3474 | mnt_flags |= MNT_READONLY; |
| 3475 | if (attr_flags & MOUNT_ATTR_NOSUID) |
| 3476 | mnt_flags |= MNT_NOSUID; |
| 3477 | if (attr_flags & MOUNT_ATTR_NODEV) |
| 3478 | mnt_flags |= MNT_NODEV; |
| 3479 | if (attr_flags & MOUNT_ATTR_NOEXEC) |
| 3480 | mnt_flags |= MNT_NOEXEC; |
| 3481 | if (attr_flags & MOUNT_ATTR_NODIRATIME) |
| 3482 | mnt_flags |= MNT_NODIRATIME; |
| 3483 | |
| 3484 | switch (attr_flags & MOUNT_ATTR__ATIME) { |
| 3485 | case MOUNT_ATTR_STRICTATIME: |
| 3486 | break; |
| 3487 | case MOUNT_ATTR_NOATIME: |
| 3488 | mnt_flags |= MNT_NOATIME; |
| 3489 | break; |
| 3490 | case MOUNT_ATTR_RELATIME: |
| 3491 | mnt_flags |= MNT_RELATIME; |
| 3492 | break; |
| 3493 | default: |
| 3494 | return -EINVAL; |
| 3495 | } |
| 3496 | |
| 3497 | f = fdget(fs_fd); |
| 3498 | if (!f.file) |
| 3499 | return -EBADF; |
| 3500 | |
| 3501 | ret = -EINVAL; |
| 3502 | if (f.file->f_op != &fscontext_fops) |
| 3503 | goto err_fsfd; |
| 3504 | |
| 3505 | fc = f.file->private_data; |
| 3506 | |
| 3507 | ret = mutex_lock_interruptible(&fc->uapi_mutex); |
| 3508 | if (ret < 0) |
| 3509 | goto err_fsfd; |
| 3510 | |
| 3511 | /* There must be a valid superblock or we can't mount it */ |
| 3512 | ret = -EINVAL; |
| 3513 | if (!fc->root) |
| 3514 | goto err_unlock; |
| 3515 | |
| 3516 | ret = -EPERM; |
| 3517 | if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { |
| 3518 | pr_warn("VFS: Mount too revealing\n"); |
| 3519 | goto err_unlock; |
| 3520 | } |
| 3521 | |
| 3522 | ret = -EBUSY; |
| 3523 | if (fc->phase != FS_CONTEXT_AWAITING_MOUNT) |
| 3524 | goto err_unlock; |
| 3525 | |
| 3526 | ret = -EPERM; |
| 3527 | if ((fc->sb_flags & SB_MANDLOCK) && !may_mandlock()) |
| 3528 | goto err_unlock; |
| 3529 | |
| 3530 | newmount.mnt = vfs_create_mount(fc); |
| 3531 | if (IS_ERR(newmount.mnt)) { |
| 3532 | ret = PTR_ERR(newmount.mnt); |
| 3533 | goto err_unlock; |
| 3534 | } |
| 3535 | newmount.dentry = dget(fc->root); |
| 3536 | newmount.mnt->mnt_flags = mnt_flags; |
| 3537 | |
| 3538 | /* We've done the mount bit - now move the file context into more or |
| 3539 | * less the same state as if we'd done an fspick(). We don't want to |
| 3540 | * do any memory allocation or anything like that at this point as we |
| 3541 | * don't want to have to handle any errors incurred. |
| 3542 | */ |
| 3543 | vfs_clean_context(fc); |
| 3544 | |
| 3545 | ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true); |
| 3546 | if (IS_ERR(ns)) { |
| 3547 | ret = PTR_ERR(ns); |
| 3548 | goto err_path; |
| 3549 | } |
| 3550 | mnt = real_mount(newmount.mnt); |
| 3551 | mnt->mnt_ns = ns; |
| 3552 | ns->root = mnt; |
| 3553 | ns->mounts = 1; |
| 3554 | list_add(&mnt->mnt_list, &ns->list); |
Eric Biggers | 1b0b9cc | 2019-06-12 11:43:13 -0700 | [diff] [blame] | 3555 | mntget(newmount.mnt); |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3556 | |
| 3557 | /* Attach to an apparent O_PATH fd with a note that we need to unmount |
| 3558 | * it, not just simply put it. |
| 3559 | */ |
| 3560 | file = dentry_open(&newmount, O_PATH, fc->cred); |
| 3561 | if (IS_ERR(file)) { |
| 3562 | dissolve_on_fput(newmount.mnt); |
| 3563 | ret = PTR_ERR(file); |
| 3564 | goto err_path; |
| 3565 | } |
| 3566 | file->f_mode |= FMODE_NEED_UNMOUNT; |
| 3567 | |
| 3568 | ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0); |
| 3569 | if (ret >= 0) |
| 3570 | fd_install(ret, file); |
| 3571 | else |
| 3572 | fput(file); |
| 3573 | |
| 3574 | err_path: |
| 3575 | path_put(&newmount); |
| 3576 | err_unlock: |
| 3577 | mutex_unlock(&fc->uapi_mutex); |
| 3578 | err_fsfd: |
| 3579 | fdput(f); |
| 3580 | return ret; |
| 3581 | } |
| 3582 | |
| 3583 | /* |
| 3584 | * Move a mount from one place to another. In combination with |
| 3585 | * fsopen()/fsmount() this is used to install a new mount and in combination |
| 3586 | * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy |
| 3587 | * a mount subtree. |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3588 | * |
| 3589 | * Note the flags value is a combination of MOVE_MOUNT_* flags. |
| 3590 | */ |
| 3591 | SYSCALL_DEFINE5(move_mount, |
Ben Dooks | 2658ce0 | 2019-10-15 11:35:02 +0100 | [diff] [blame] | 3592 | int, from_dfd, const char __user *, from_pathname, |
| 3593 | int, to_dfd, const char __user *, to_pathname, |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3594 | unsigned int, flags) |
| 3595 | { |
| 3596 | struct path from_path, to_path; |
| 3597 | unsigned int lflags; |
| 3598 | int ret = 0; |
| 3599 | |
| 3600 | if (!may_mount()) |
| 3601 | return -EPERM; |
| 3602 | |
| 3603 | if (flags & ~MOVE_MOUNT__MASK) |
| 3604 | return -EINVAL; |
| 3605 | |
| 3606 | /* If someone gives a pathname, they aren't permitted to move |
| 3607 | * from an fd that requires unmount as we can't get at the flag |
| 3608 | * to clear it afterwards. |
| 3609 | */ |
| 3610 | lflags = 0; |
| 3611 | if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW; |
| 3612 | if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; |
| 3613 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY; |
| 3614 | |
| 3615 | ret = user_path_at(from_dfd, from_pathname, lflags, &from_path); |
| 3616 | if (ret < 0) |
| 3617 | return ret; |
| 3618 | |
| 3619 | lflags = 0; |
| 3620 | if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW; |
| 3621 | if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; |
| 3622 | if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY; |
| 3623 | |
| 3624 | ret = user_path_at(to_dfd, to_pathname, lflags, &to_path); |
| 3625 | if (ret < 0) |
| 3626 | goto out_from; |
| 3627 | |
| 3628 | ret = security_move_mount(&from_path, &to_path); |
| 3629 | if (ret < 0) |
| 3630 | goto out_to; |
| 3631 | |
| 3632 | ret = do_move_mount(&from_path, &to_path); |
| 3633 | |
| 3634 | out_to: |
| 3635 | path_put(&to_path); |
| 3636 | out_from: |
| 3637 | path_put(&from_path); |
| 3638 | return ret; |
| 3639 | } |
| 3640 | |
| 3641 | /* |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3642 | * Return true if path is reachable from root |
| 3643 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3644 | * namespace_sem or mount_lock is held |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3645 | */ |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3646 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3647 | const struct path *root) |
| 3648 | { |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3649 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 3650 | dentry = mnt->mnt_mountpoint; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 3651 | mnt = mnt->mnt_parent; |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3652 | } |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3653 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3654 | } |
| 3655 | |
Mickaël Salaün | 640eb7e | 2016-11-14 22:14:35 +0100 | [diff] [blame] | 3656 | bool path_is_under(const struct path *path1, const struct path *path2) |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3657 | { |
Yaowei Bai | 25ab4c9 | 2015-11-17 14:40:10 +0800 | [diff] [blame] | 3658 | bool res; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3659 | read_seqlock_excl(&mount_lock); |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 3660 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3661 | read_sequnlock_excl(&mount_lock); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 3662 | return res; |
| 3663 | } |
| 3664 | EXPORT_SYMBOL(path_is_under); |
| 3665 | |
| 3666 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3667 | * pivot_root Semantics: |
| 3668 | * Moves the root file system of the current process to the directory put_old, |
| 3669 | * makes new_root as the new root file system of the current process, and sets |
| 3670 | * root/cwd of all processes which had them on the current root to new_root. |
| 3671 | * |
| 3672 | * Restrictions: |
| 3673 | * The new_root and put_old must be directories, and must not be on the |
| 3674 | * same file system as the current process root. The put_old must be |
| 3675 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 3676 | * pointed to by put_old must yield the same directory as new_root. No other |
| 3677 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 3678 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 3679 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
Mauro Carvalho Chehab | 0c1bc6b | 2020-04-14 18:48:37 +0200 | [diff] [blame] | 3680 | * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 3681 | * in this situation. |
| 3682 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3683 | * Notes: |
| 3684 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 3685 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 3686 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 3687 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 3688 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 3689 | * first. |
| 3690 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 3691 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 3692 | const char __user *, put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3693 | { |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3694 | struct path new, old, root; |
| 3695 | struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3696 | struct mountpoint *old_mp, *root_mp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3697 | int error; |
| 3698 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 3699 | if (!may_mount()) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3700 | return -EPERM; |
| 3701 | |
Al Viro | ce6595a | 2019-07-14 16:42:44 -0400 | [diff] [blame] | 3702 | error = user_path_at(AT_FDCWD, new_root, |
| 3703 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3704 | if (error) |
| 3705 | goto out0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3706 | |
Al Viro | ce6595a | 2019-07-14 16:42:44 -0400 | [diff] [blame] | 3707 | error = user_path_at(AT_FDCWD, put_old, |
| 3708 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3709 | if (error) |
| 3710 | goto out1; |
| 3711 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3712 | error = security_sb_pivotroot(&old, &new); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3713 | if (error) |
| 3714 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3715 | |
Miklos Szeredi | f7ad3c6 | 2010-08-10 11:41:36 +0200 | [diff] [blame] | 3716 | get_fs_root(current->fs, &root); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3717 | old_mp = lock_mount(&old); |
| 3718 | error = PTR_ERR(old_mp); |
| 3719 | if (IS_ERR(old_mp)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3720 | goto out3; |
| 3721 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3722 | error = -EINVAL; |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 3723 | new_mnt = real_mount(new.mnt); |
| 3724 | root_mnt = real_mount(root.mnt); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3725 | old_mnt = real_mount(old.mnt); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3726 | ex_parent = new_mnt->mnt_parent; |
| 3727 | root_parent = root_mnt->mnt_parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3728 | if (IS_MNT_SHARED(old_mnt) || |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3729 | IS_MNT_SHARED(ex_parent) || |
| 3730 | IS_MNT_SHARED(root_parent)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3731 | goto out4; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3732 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3733 | goto out4; |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 3734 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
| 3735 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3736 | error = -ENOENT; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 3737 | if (d_unlinked(new.dentry)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3738 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3739 | error = -EBUSY; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3740 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3741 | goto out4; /* loop, on the same file system */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3742 | error = -EINVAL; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 3743 | if (root.mnt->mnt_root != root.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3744 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3745 | if (!mnt_has_parent(root_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3746 | goto out4; /* not attached */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3747 | if (new.mnt->mnt_root != new.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3748 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3749 | if (!mnt_has_parent(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3750 | goto out4; /* not attached */ |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3751 | /* make sure we can reach put_old from new_root */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3752 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3753 | goto out4; |
Eric W. Biederman | 0d08260 | 2014-10-08 10:42:27 -0700 | [diff] [blame] | 3754 | /* make certain new is below the root */ |
| 3755 | if (!is_path_reachable(new_mnt, new.dentry, &root)) |
| 3756 | goto out4; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3757 | lock_mount_hash(); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3758 | umount_mnt(new_mnt); |
| 3759 | root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 3760 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
| 3761 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; |
| 3762 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 3763 | } |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3764 | /* mount old root on put_old */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3765 | attach_mnt(root_mnt, old_mnt, old_mp); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3766 | /* mount new_root on / */ |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3767 | attach_mnt(new_mnt, root_parent, root_mp); |
| 3768 | mnt_add_count(root_parent, -1); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3769 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
Eric W. Biederman | 4fed655 | 2014-10-08 10:42:57 -0700 | [diff] [blame] | 3770 | /* A moved mount should not expire automatically */ |
| 3771 | list_del_init(&new_mnt->mnt_expire); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 3772 | put_mountpoint(root_mp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3773 | unlock_mount_hash(); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3774 | chroot_fs_refs(&root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3775 | error = 0; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3776 | out4: |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3777 | unlock_mount(old_mp); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3778 | if (!error) |
| 3779 | mntput_no_expire(ex_parent); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3780 | out3: |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 3781 | path_put(&root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 3782 | out2: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3783 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3784 | out1: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 3785 | path_put(&new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3786 | out0: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3787 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3788 | } |
| 3789 | |
| 3790 | static void __init init_mount_tree(void) |
| 3791 | { |
| 3792 | struct vfsmount *mnt; |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3793 | struct mount *m; |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3794 | struct mnt_namespace *ns; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 3795 | struct path root; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3796 | |
Al Viro | fd3e007 | 2019-05-30 17:48:35 -0400 | [diff] [blame] | 3797 | mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3798 | if (IS_ERR(mnt)) |
| 3799 | panic("Can't create rootfs"); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 3800 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3801 | ns = alloc_mnt_ns(&init_user_ns, false); |
Trond Myklebust | 3b22edc | 2009-06-23 17:29:49 -0400 | [diff] [blame] | 3802 | if (IS_ERR(ns)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3803 | panic("Can't allocate initial namespace"); |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3804 | m = real_mount(mnt); |
| 3805 | m->mnt_ns = ns; |
| 3806 | ns->root = m; |
| 3807 | ns->mounts = 1; |
| 3808 | list_add(&m->mnt_list, &ns->list); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3809 | init_task.nsproxy->mnt_ns = ns; |
| 3810 | get_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3811 | |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 3812 | root.mnt = mnt; |
| 3813 | root.dentry = mnt->mnt_root; |
Eric W. Biederman | da362b0 | 2014-10-07 12:19:53 -0700 | [diff] [blame] | 3814 | mnt->mnt_flags |= MNT_LOCKED; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 3815 | |
| 3816 | set_fs_pwd(current->fs, &root); |
| 3817 | set_fs_root(current->fs, &root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3818 | } |
| 3819 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 3820 | void __init mnt_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3821 | { |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 3822 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3823 | |
Al Viro | 7d6fec4 | 2011-11-23 12:14:10 -0500 | [diff] [blame] | 3824 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 3825 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3826 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3827 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 3828 | sizeof(struct hlist_head), |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3829 | mhash_entries, 19, |
Pavel Tatashin | 3d375d7 | 2017-07-06 15:39:11 -0700 | [diff] [blame] | 3830 | HASH_ZERO, |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3831 | &m_hash_shift, &m_hash_mask, 0, 0); |
| 3832 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", |
| 3833 | sizeof(struct hlist_head), |
| 3834 | mphash_entries, 19, |
Pavel Tatashin | 3d375d7 | 2017-07-06 15:39:11 -0700 | [diff] [blame] | 3835 | HASH_ZERO, |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 3836 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3837 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3838 | if (!mount_hashtable || !mountpoint_hashtable) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3839 | panic("Failed to allocate mount hash table\n"); |
| 3840 | |
Tejun Heo | 4b93dc9 | 2013-11-28 14:54:43 -0500 | [diff] [blame] | 3841 | kernfs_init(); |
| 3842 | |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 3843 | err = sysfs_init(); |
| 3844 | if (err) |
| 3845 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 3846 | __func__, err); |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 3847 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 3848 | if (!fs_kobj) |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 3849 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
Al Viro | 037f11b | 2019-06-01 18:09:44 -0400 | [diff] [blame] | 3850 | shmem_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3851 | init_rootfs(); |
| 3852 | init_mount_tree(); |
| 3853 | } |
| 3854 | |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3855 | void put_mnt_ns(struct mnt_namespace *ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3856 | { |
Kirill Tkhai | 1a7b8969 | 2020-08-03 13:16:42 +0300 | [diff] [blame] | 3857 | if (!refcount_dec_and_test(&ns->ns.count)) |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3858 | return; |
Al Viro | 7b00ed6 | 2013-09-16 21:19:20 -0400 | [diff] [blame] | 3859 | drop_collected_mounts(&ns->root->mnt); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3860 | free_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3861 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3862 | |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 3863 | struct vfsmount *kern_mount(struct file_system_type *type) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3864 | { |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3865 | struct vfsmount *mnt; |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 3866 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3867 | if (!IS_ERR(mnt)) { |
| 3868 | /* |
| 3869 | * it is a longterm mount, don't release mnt until |
| 3870 | * we unmount before file sys is unregistered |
| 3871 | */ |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 3872 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3873 | } |
| 3874 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3875 | } |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 3876 | EXPORT_SYMBOL_GPL(kern_mount); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3877 | |
| 3878 | void kern_unmount(struct vfsmount *mnt) |
| 3879 | { |
| 3880 | /* release long term mount so mount point can be released */ |
| 3881 | if (!IS_ERR_OR_NULL(mnt)) { |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 3882 | real_mount(mnt)->mnt_ns = NULL; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3883 | synchronize_rcu(); /* yecchhh... */ |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 3884 | mntput(mnt); |
| 3885 | } |
| 3886 | } |
| 3887 | EXPORT_SYMBOL(kern_unmount); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3888 | |
Miklos Szeredi | df820f8 | 2020-06-04 10:48:19 +0200 | [diff] [blame] | 3889 | void kern_unmount_array(struct vfsmount *mnt[], unsigned int num) |
| 3890 | { |
| 3891 | unsigned int i; |
| 3892 | |
| 3893 | for (i = 0; i < num; i++) |
| 3894 | if (mnt[i]) |
| 3895 | real_mount(mnt[i])->mnt_ns = NULL; |
| 3896 | synchronize_rcu_expedited(); |
| 3897 | for (i = 0; i < num; i++) |
| 3898 | mntput(mnt[i]); |
| 3899 | } |
| 3900 | EXPORT_SYMBOL(kern_unmount_array); |
| 3901 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3902 | bool our_mnt(struct vfsmount *mnt) |
| 3903 | { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3904 | return check_mnt(real_mount(mnt)); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 3905 | } |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3906 | |
Eric W. Biederman | 3151527 | 2013-03-15 01:45:51 -0700 | [diff] [blame] | 3907 | bool current_chrooted(void) |
| 3908 | { |
| 3909 | /* Does the current process have a non-standard root */ |
| 3910 | struct path ns_root; |
| 3911 | struct path fs_root; |
| 3912 | bool chrooted; |
| 3913 | |
| 3914 | /* Find the namespace root */ |
| 3915 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; |
| 3916 | ns_root.dentry = ns_root.mnt->mnt_root; |
| 3917 | path_get(&ns_root); |
| 3918 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) |
| 3919 | ; |
| 3920 | |
| 3921 | get_fs_root(current->fs, &fs_root); |
| 3922 | |
| 3923 | chrooted = !path_equal(&fs_root, &ns_root); |
| 3924 | |
| 3925 | path_put(&fs_root); |
| 3926 | path_put(&ns_root); |
| 3927 | |
| 3928 | return chrooted; |
| 3929 | } |
| 3930 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3931 | static bool mnt_already_visible(struct mnt_namespace *ns, |
| 3932 | const struct super_block *sb, |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3933 | int *new_mnt_flags) |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3934 | { |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3935 | int new_flags = *new_mnt_flags; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3936 | struct mount *mnt; |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3937 | bool visible = false; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3938 | |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 3939 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 3940 | lock_ns_list(ns); |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3941 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3942 | struct mount *child; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3943 | int mnt_flags; |
| 3944 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 3945 | if (mnt_is_cursor(mnt)) |
| 3946 | continue; |
| 3947 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3948 | if (mnt->mnt.mnt_sb->s_type != sb->s_type) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3949 | continue; |
| 3950 | |
Eric W. Biederman | 7e96c1b | 2015-05-08 16:36:50 -0500 | [diff] [blame] | 3951 | /* This mount is not fully visible if it's root directory |
| 3952 | * is not the root directory of the filesystem. |
| 3953 | */ |
| 3954 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) |
| 3955 | continue; |
| 3956 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 3957 | /* A local view of the mount flags */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3958 | mnt_flags = mnt->mnt.mnt_flags; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3959 | |
Eric W. Biederman | 695e9df | 2016-06-10 12:21:40 -0500 | [diff] [blame] | 3960 | /* Don't miss readonly hidden in the superblock flags */ |
David Howells | bc98a42 | 2017-07-17 08:45:34 +0100 | [diff] [blame] | 3961 | if (sb_rdonly(mnt->mnt.mnt_sb)) |
Eric W. Biederman | 695e9df | 2016-06-10 12:21:40 -0500 | [diff] [blame] | 3962 | mnt_flags |= MNT_LOCK_READONLY; |
| 3963 | |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3964 | /* Verify the mount flags are equal to or more permissive |
| 3965 | * than the proposed new mount. |
| 3966 | */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3967 | if ((mnt_flags & MNT_LOCK_READONLY) && |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3968 | !(new_flags & MNT_READONLY)) |
| 3969 | continue; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3970 | if ((mnt_flags & MNT_LOCK_ATIME) && |
| 3971 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3972 | continue; |
| 3973 | |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3974 | /* This mount is not fully visible if there are any |
| 3975 | * locked child mounts that cover anything except for |
| 3976 | * empty directories. |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3977 | */ |
| 3978 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 3979 | struct inode *inode = child->mnt_mountpoint->d_inode; |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3980 | /* Only worry about locked mounts */ |
Eric W. Biederman | d71ed6c | 2016-05-27 14:50:05 -0500 | [diff] [blame] | 3981 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 3982 | continue; |
Eric W. Biederman | 7236c85 | 2015-05-13 20:51:09 -0500 | [diff] [blame] | 3983 | /* Is the directory permanetly empty? */ |
| 3984 | if (!is_empty_dir_inode(inode)) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3985 | goto next; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3986 | } |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 3987 | /* Preserve the locked attributes */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3988 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 3989 | MNT_LOCK_ATIME); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3990 | visible = true; |
| 3991 | goto found; |
| 3992 | next: ; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3993 | } |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3994 | found: |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 3995 | unlock_ns_list(ns); |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 3996 | up_read(&namespace_sem); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 3997 | return visible; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 3998 | } |
| 3999 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4000 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags) |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4001 | { |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 4002 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4003 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 4004 | unsigned long s_iflags; |
| 4005 | |
| 4006 | if (ns->user_ns == &init_user_ns) |
| 4007 | return false; |
| 4008 | |
| 4009 | /* Can this filesystem be too revealing? */ |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4010 | s_iflags = sb->s_iflags; |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4011 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
| 4012 | return false; |
| 4013 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 4014 | if ((s_iflags & required_iflags) != required_iflags) { |
| 4015 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", |
| 4016 | required_iflags); |
| 4017 | return true; |
| 4018 | } |
| 4019 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4020 | return !mnt_already_visible(ns, sb, new_mnt_flags); |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4021 | } |
| 4022 | |
Andy Lutomirski | 380cf5b | 2016-06-23 16:41:05 -0500 | [diff] [blame] | 4023 | bool mnt_may_suid(struct vfsmount *mnt) |
| 4024 | { |
| 4025 | /* |
| 4026 | * Foreign mounts (accessed via fchdir or through /proc |
| 4027 | * symlinks) are always treated as if they are nosuid. This |
| 4028 | * prevents namespaces from trusting potentially unsafe |
| 4029 | * suid/sgid bits, file caps, or security labels that originate |
| 4030 | * in other namespaces. |
| 4031 | */ |
| 4032 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && |
| 4033 | current_in_userns(mnt->mnt_sb->s_user_ns); |
| 4034 | } |
| 4035 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 4036 | static struct ns_common *mntns_get(struct task_struct *task) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4037 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4038 | struct ns_common *ns = NULL; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4039 | struct nsproxy *nsproxy; |
| 4040 | |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 4041 | task_lock(task); |
| 4042 | nsproxy = task->nsproxy; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4043 | if (nsproxy) { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4044 | ns = &nsproxy->mnt_ns->ns; |
| 4045 | get_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4046 | } |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 4047 | task_unlock(task); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4048 | |
| 4049 | return ns; |
| 4050 | } |
| 4051 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 4052 | static void mntns_put(struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4053 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4054 | put_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4055 | } |
| 4056 | |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4057 | static int mntns_install(struct nsset *nsset, struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4058 | { |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4059 | struct nsproxy *nsproxy = nsset->nsproxy; |
| 4060 | struct fs_struct *fs = nsset->fs; |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4061 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns; |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4062 | struct user_namespace *user_ns = nsset->cred->user_ns; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4063 | struct path root; |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4064 | int err; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4065 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 4066 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4067 | !ns_capable(user_ns, CAP_SYS_CHROOT) || |
| 4068 | !ns_capable(user_ns, CAP_SYS_ADMIN)) |
Zhao Hongjiang | ae11e0f | 2012-09-13 16:38:03 +0800 | [diff] [blame] | 4069 | return -EPERM; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4070 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 4071 | if (is_anon_ns(mnt_ns)) |
| 4072 | return -EINVAL; |
| 4073 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4074 | if (fs->users != 1) |
| 4075 | return -EINVAL; |
| 4076 | |
| 4077 | get_mnt_ns(mnt_ns); |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4078 | old_mnt_ns = nsproxy->mnt_ns; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4079 | nsproxy->mnt_ns = mnt_ns; |
| 4080 | |
| 4081 | /* Find the root */ |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4082 | err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt, |
| 4083 | "/", LOOKUP_DOWN, &root); |
| 4084 | if (err) { |
| 4085 | /* revert to old namespace */ |
| 4086 | nsproxy->mnt_ns = old_mnt_ns; |
| 4087 | put_mnt_ns(mnt_ns); |
| 4088 | return err; |
| 4089 | } |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4090 | |
Andrei Vagin | 4068367 | 2017-06-08 17:32:29 -0700 | [diff] [blame] | 4091 | put_mnt_ns(old_mnt_ns); |
| 4092 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4093 | /* Update the pwd and root */ |
| 4094 | set_fs_pwd(fs, &root); |
| 4095 | set_fs_root(fs, &root); |
| 4096 | |
| 4097 | path_put(&root); |
| 4098 | return 0; |
| 4099 | } |
| 4100 | |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 4101 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
| 4102 | { |
| 4103 | return to_mnt_ns(ns)->user_ns; |
| 4104 | } |
| 4105 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4106 | const struct proc_ns_operations mntns_operations = { |
| 4107 | .name = "mnt", |
| 4108 | .type = CLONE_NEWNS, |
| 4109 | .get = mntns_get, |
| 4110 | .put = mntns_put, |
| 4111 | .install = mntns_install, |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 4112 | .owner = mntns_owner, |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4113 | }; |