Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/fs/namespace.c |
| 3 | * |
| 4 | * (C) Copyright Al Viro 2000, 2001 |
| 5 | * Released under GPL v2. |
| 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 | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [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> |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 18 | #include <linux/idr.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 19 | #include <linux/acct.h> /* acct_auto_close_mnt */ |
| 20 | #include <linux/ramfs.h> /* init_rootfs */ |
| 21 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
| 22 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ |
| 23 | #include <linux/uaccess.h> |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 24 | #include <linux/proc_fs.h> |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 25 | #include "pnode.h" |
Adrian Bunk | 948730b | 2007-07-15 23:41:25 -0700 | [diff] [blame] | 26 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 28 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
| 29 | #define HASH_SIZE (1UL << HASH_SHIFT) |
| 30 | |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 31 | static int event; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 32 | static DEFINE_IDA(mnt_id_ida); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 33 | static DEFINE_IDA(mnt_group_ida); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 34 | static DEFINE_SPINLOCK(mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 35 | static int mnt_id_start = 0; |
| 36 | static int mnt_group_start = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | |
Eric Dumazet | fa3536c | 2006-03-26 01:37:24 -0800 | [diff] [blame] | 38 | static struct list_head *mount_hashtable __read_mostly; |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 39 | static struct kmem_cache *mnt_cache __read_mostly; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 40 | static struct rw_semaphore namespace_sem; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 42 | /* /sys/fs */ |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 43 | struct kobject *fs_kobj; |
| 44 | EXPORT_SYMBOL_GPL(fs_kobj); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 45 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 46 | /* |
| 47 | * vfsmount lock may be taken for read to prevent changes to the |
| 48 | * vfsmount hash, ie. during mountpoint lookups or walking back |
| 49 | * up the tree. |
| 50 | * |
| 51 | * It should be taken for write in all cases where the vfsmount |
| 52 | * tree or hash is modified or when a vfsmount structure is modified. |
| 53 | */ |
| 54 | DEFINE_BRLOCK(vfsmount_lock); |
| 55 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
| 57 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 58 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 59 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 60 | tmp = tmp + (tmp >> HASH_SHIFT); |
| 61 | return tmp & (HASH_SIZE - 1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | } |
| 63 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 64 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
| 65 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 66 | /* |
| 67 | * allocation is serialized by namespace_sem, but we need the spinlock to |
| 68 | * serialize with freeing. |
| 69 | */ |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 70 | static int mnt_alloc_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 71 | { |
| 72 | int res; |
| 73 | |
| 74 | retry: |
| 75 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 76 | spin_lock(&mnt_id_lock); |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 77 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 78 | if (!res) |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 79 | mnt_id_start = mnt->mnt_id + 1; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 80 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 81 | if (res == -EAGAIN) |
| 82 | goto retry; |
| 83 | |
| 84 | return res; |
| 85 | } |
| 86 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 87 | static void mnt_free_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 88 | { |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 89 | int id = mnt->mnt_id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 90 | spin_lock(&mnt_id_lock); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 91 | ida_remove(&mnt_id_ida, id); |
| 92 | if (mnt_id_start > id) |
| 93 | mnt_id_start = id; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 94 | spin_unlock(&mnt_id_lock); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 95 | } |
| 96 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 97 | /* |
| 98 | * Allocate a new peer group ID |
| 99 | * |
| 100 | * mnt_group_ida is protected by namespace_sem |
| 101 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 102 | static int mnt_alloc_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 103 | { |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 104 | int res; |
| 105 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 106 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
| 107 | return -ENOMEM; |
| 108 | |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 109 | res = ida_get_new_above(&mnt_group_ida, |
| 110 | mnt_group_start, |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 111 | &mnt->mnt_group_id); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 112 | if (!res) |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 113 | mnt_group_start = mnt->mnt_group_id + 1; |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 114 | |
| 115 | return res; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 116 | } |
| 117 | |
| 118 | /* |
| 119 | * Release a peer group ID |
| 120 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 121 | void mnt_release_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 122 | { |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 123 | int id = mnt->mnt_group_id; |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 124 | ida_remove(&mnt_group_ida, id); |
| 125 | if (mnt_group_start > id) |
| 126 | mnt_group_start = id; |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 127 | mnt->mnt_group_id = 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 128 | } |
| 129 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 130 | /* |
| 131 | * vfsmount lock must be held for read |
| 132 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 133 | static inline void mnt_add_count(struct mount *mnt, int n) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 134 | { |
| 135 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 136 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 137 | #else |
| 138 | preempt_disable(); |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 139 | mnt->mnt_count += n; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 140 | preempt_enable(); |
| 141 | #endif |
| 142 | } |
| 143 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 144 | /* |
| 145 | * vfsmount lock must be held for write |
| 146 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 147 | unsigned int mnt_get_count(struct mount *mnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 148 | { |
| 149 | #ifdef CONFIG_SMP |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 150 | unsigned int count = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 151 | int cpu; |
| 152 | |
| 153 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 154 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 155 | } |
| 156 | |
| 157 | return count; |
| 158 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 159 | return mnt->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 160 | #endif |
| 161 | } |
| 162 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 163 | static struct mount *alloc_vfsmnt(const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 164 | { |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 165 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
| 166 | if (mnt) { |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 167 | int err; |
| 168 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 169 | err = mnt_alloc_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 170 | if (err) |
| 171 | goto out_free_cache; |
| 172 | |
| 173 | if (name) { |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 174 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); |
| 175 | if (!mnt->mnt_devname) |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 176 | goto out_free_id; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 177 | } |
| 178 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 179 | #ifdef CONFIG_SMP |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 180 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
| 181 | if (!mnt->mnt_pcp) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 182 | goto out_free_devname; |
| 183 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 184 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 185 | #else |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 186 | mnt->mnt_count = 1; |
| 187 | mnt->mnt_writers = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 188 | #endif |
| 189 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 190 | INIT_LIST_HEAD(&mnt->mnt_hash); |
| 191 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 192 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 193 | INIT_LIST_HEAD(&mnt->mnt_list); |
| 194 | INIT_LIST_HEAD(&mnt->mnt_expire); |
| 195 | INIT_LIST_HEAD(&mnt->mnt_share); |
| 196 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 197 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Andreas Gruenbacher | 2504c5d | 2009-12-17 21:24:27 -0500 | [diff] [blame] | 198 | #ifdef CONFIG_FSNOTIFY |
| 199 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); |
| 200 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 201 | } |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 202 | return mnt; |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 203 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 204 | #ifdef CONFIG_SMP |
| 205 | out_free_devname: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 206 | kfree(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 207 | #endif |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 208 | out_free_id: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 209 | mnt_free_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 210 | out_free_cache: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 211 | kmem_cache_free(mnt_cache, mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 212 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | } |
| 214 | |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 215 | /* |
| 216 | * Most r/o checks on a fs are for operations that take |
| 217 | * discrete amounts of time, like a write() or unlink(). |
| 218 | * We must keep track of when those operations start |
| 219 | * (for permission checks) and when they end, so that |
| 220 | * we can determine when writes are able to occur to |
| 221 | * a filesystem. |
| 222 | */ |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 223 | /* |
| 224 | * __mnt_is_readonly: check whether a mount is read-only |
| 225 | * @mnt: the mount to check for its write status |
| 226 | * |
| 227 | * This shouldn't be used directly ouside of the VFS. |
| 228 | * It does not guarantee that the filesystem will stay |
| 229 | * r/w, just that it is right *now*. This can not and |
| 230 | * should not be used in place of IS_RDONLY(inode). |
| 231 | * mnt_want/drop_write() will _keep_ the filesystem |
| 232 | * r/w. |
| 233 | */ |
| 234 | int __mnt_is_readonly(struct vfsmount *mnt) |
| 235 | { |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 236 | if (mnt->mnt_flags & MNT_READONLY) |
| 237 | return 1; |
| 238 | if (mnt->mnt_sb->s_flags & MS_RDONLY) |
| 239 | return 1; |
| 240 | return 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 241 | } |
| 242 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 243 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 244 | static inline void mnt_inc_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 245 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 246 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 247 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 248 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 249 | mnt->mnt_writers++; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 250 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 251 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 252 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 253 | static inline void mnt_dec_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 254 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 255 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 256 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 257 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 258 | mnt->mnt_writers--; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 259 | #endif |
| 260 | } |
| 261 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 262 | static unsigned int mnt_get_writers(struct mount *mnt) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 263 | { |
| 264 | #ifdef CONFIG_SMP |
| 265 | unsigned int count = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 266 | int cpu; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 267 | |
| 268 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 269 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 270 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 271 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 272 | return count; |
| 273 | #else |
| 274 | return mnt->mnt_writers; |
| 275 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 276 | } |
| 277 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 278 | static int mnt_is_readonly(struct vfsmount *mnt) |
| 279 | { |
| 280 | if (mnt->mnt_sb->s_readonly_remount) |
| 281 | return 1; |
| 282 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ |
| 283 | smp_rmb(); |
| 284 | return __mnt_is_readonly(mnt); |
| 285 | } |
| 286 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 287 | /* |
| 288 | * Most r/o checks on a fs are for operations that take |
| 289 | * discrete amounts of time, like a write() or unlink(). |
| 290 | * We must keep track of when those operations start |
| 291 | * (for permission checks) and when they end, so that |
| 292 | * we can determine when writes are able to occur to |
| 293 | * a filesystem. |
| 294 | */ |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 295 | /** |
| 296 | * mnt_want_write - get write access to a mount |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 297 | * @m: the mount on which to take a write |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 298 | * |
| 299 | * This tells the low-level filesystem that a write is |
| 300 | * about to be performed to it, and makes sure that |
| 301 | * writes are allowed before returning success. When |
| 302 | * the write operation is finished, mnt_drop_write() |
| 303 | * must be called. This is effectively a refcount. |
| 304 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 305 | int mnt_want_write(struct vfsmount *m) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 306 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 307 | struct mount *mnt = real_mount(m); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 308 | int ret = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 309 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 310 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 311 | mnt_inc_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 312 | /* |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 313 | * 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] | 314 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 315 | * incremented count after it has set MNT_WRITE_HOLD. |
| 316 | */ |
| 317 | smp_mb(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 318 | while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 319 | cpu_relax(); |
| 320 | /* |
| 321 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will |
| 322 | * be set to match its requirements. So we must not load that until |
| 323 | * MNT_WRITE_HOLD is cleared. |
| 324 | */ |
| 325 | smp_rmb(); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 326 | if (mnt_is_readonly(m)) { |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 327 | mnt_dec_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 328 | ret = -EROFS; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 329 | } |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 330 | preempt_enable(); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 331 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 332 | } |
| 333 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 334 | |
| 335 | /** |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 336 | * mnt_clone_write - get write access to a mount |
| 337 | * @mnt: the mount on which to take a write |
| 338 | * |
| 339 | * This is effectively like mnt_want_write, except |
| 340 | * it must only be used to take an extra write reference |
| 341 | * on a mountpoint that we already know has a write reference |
| 342 | * on it. This allows some optimisation. |
| 343 | * |
| 344 | * After finished, mnt_drop_write must be called as usual to |
| 345 | * drop the reference. |
| 346 | */ |
| 347 | int mnt_clone_write(struct vfsmount *mnt) |
| 348 | { |
| 349 | /* superblock may be r/o */ |
| 350 | if (__mnt_is_readonly(mnt)) |
| 351 | return -EROFS; |
| 352 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 353 | mnt_inc_writers(real_mount(mnt)); |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 354 | preempt_enable(); |
| 355 | return 0; |
| 356 | } |
| 357 | EXPORT_SYMBOL_GPL(mnt_clone_write); |
| 358 | |
| 359 | /** |
| 360 | * mnt_want_write_file - get write access to a file's mount |
| 361 | * @file: the file who's mount on which to take a write |
| 362 | * |
| 363 | * This is like mnt_want_write, but it takes a file and can |
| 364 | * do some optimisations if the file is open for write already |
| 365 | */ |
| 366 | int mnt_want_write_file(struct file *file) |
| 367 | { |
OGAWA Hirofumi | 2d8dd38 | 2009-08-06 15:07:39 -0700 | [diff] [blame] | 368 | struct inode *inode = file->f_dentry->d_inode; |
| 369 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 370 | return mnt_want_write(file->f_path.mnt); |
| 371 | else |
| 372 | return mnt_clone_write(file->f_path.mnt); |
| 373 | } |
| 374 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
| 375 | |
| 376 | /** |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 377 | * mnt_drop_write - give up write access to a mount |
| 378 | * @mnt: the mount on which to give up write access |
| 379 | * |
| 380 | * Tells the low-level filesystem that we are done |
| 381 | * performing writes to it. Must be matched with |
| 382 | * mnt_want_write() call above. |
| 383 | */ |
| 384 | void mnt_drop_write(struct vfsmount *mnt) |
| 385 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 386 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 387 | mnt_dec_writers(real_mount(mnt)); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 388 | preempt_enable(); |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 389 | } |
| 390 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 391 | |
Al Viro | 2a79f17 | 2011-12-09 08:06:57 -0500 | [diff] [blame] | 392 | void mnt_drop_write_file(struct file *file) |
| 393 | { |
| 394 | mnt_drop_write(file->f_path.mnt); |
| 395 | } |
| 396 | EXPORT_SYMBOL(mnt_drop_write_file); |
| 397 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 398 | static int mnt_make_readonly(struct mount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 399 | { |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 400 | int ret = 0; |
| 401 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 402 | br_write_lock(&vfsmount_lock); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 403 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 404 | /* |
| 405 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 406 | * should be visible before we do. |
| 407 | */ |
| 408 | smp_mb(); |
| 409 | |
| 410 | /* |
| 411 | * With writers on hold, if this value is zero, then there are |
| 412 | * definitely no active writers (although held writers may subsequently |
| 413 | * increment the count, they'll have to wait, and decrement it after |
| 414 | * seeing MNT_READONLY). |
| 415 | * |
| 416 | * It is OK to have counter incremented on one CPU and decremented on |
| 417 | * another: the sum will add up correctly. The danger would be when we |
| 418 | * sum up each counter, if we read a counter before it is incremented, |
| 419 | * but then read another CPU's count which it has been subsequently |
| 420 | * decremented from -- we would see more decrements than we should. |
| 421 | * MNT_WRITE_HOLD protects against this scenario, because |
| 422 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 423 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 424 | * we're counting up here. |
| 425 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 426 | if (mnt_get_writers(mnt) > 0) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 427 | ret = -EBUSY; |
| 428 | else |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 429 | mnt->mnt.mnt_flags |= MNT_READONLY; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 430 | /* |
| 431 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 432 | * that become unheld will see MNT_READONLY. |
| 433 | */ |
| 434 | smp_wmb(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 435 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 436 | br_write_unlock(&vfsmount_lock); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 437 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 438 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 439 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 440 | static void __mnt_unmake_readonly(struct mount *mnt) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 441 | { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 442 | br_write_lock(&vfsmount_lock); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 443 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 444 | br_write_unlock(&vfsmount_lock); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 445 | } |
| 446 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 447 | int sb_prepare_remount_readonly(struct super_block *sb) |
| 448 | { |
| 449 | struct mount *mnt; |
| 450 | int err = 0; |
| 451 | |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 452 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
| 453 | if (atomic_long_read(&sb->s_remove_count)) |
| 454 | return -EBUSY; |
| 455 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 456 | br_write_lock(&vfsmount_lock); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 457 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 458 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { |
| 459 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
| 460 | smp_mb(); |
| 461 | if (mnt_get_writers(mnt) > 0) { |
| 462 | err = -EBUSY; |
| 463 | break; |
| 464 | } |
| 465 | } |
| 466 | } |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 467 | if (!err && atomic_long_read(&sb->s_remove_count)) |
| 468 | err = -EBUSY; |
| 469 | |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 470 | if (!err) { |
| 471 | sb->s_readonly_remount = 1; |
| 472 | smp_wmb(); |
| 473 | } |
| 474 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 475 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
| 476 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
| 477 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 478 | br_write_unlock(&vfsmount_lock); |
Miklos Szeredi | 4ed5e82 | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 479 | |
| 480 | return err; |
| 481 | } |
| 482 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 483 | static void free_vfsmnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 484 | { |
Al Viro | 52ba162 | 2011-11-25 02:25:17 -0500 | [diff] [blame] | 485 | kfree(mnt->mnt_devname); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 486 | mnt_free_id(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 487 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 488 | free_percpu(mnt->mnt_pcp); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 489 | #endif |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 490 | kmem_cache_free(mnt_cache, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 491 | } |
| 492 | |
| 493 | /* |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 494 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
| 495 | * @dir. If @dir is set return the first mount else return the last mount. |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 496 | * vfsmount_lock must be held for read or write. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 497 | */ |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 498 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 499 | int dir) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 501 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
| 502 | struct list_head *tmp = head; |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 503 | struct mount *p, *found = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 504 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 505 | for (;;) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 506 | tmp = dir ? tmp->next : tmp->prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | p = NULL; |
| 508 | if (tmp == head) |
| 509 | break; |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 510 | p = list_entry(tmp, struct mount, mnt_hash); |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 511 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) { |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 512 | found = p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 513 | break; |
| 514 | } |
| 515 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 516 | return found; |
| 517 | } |
| 518 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 519 | /* |
| 520 | * lookup_mnt increments the ref count before returning |
| 521 | * the vfsmount struct. |
| 522 | */ |
Al Viro | 1c755af | 2009-04-18 14:06:57 -0400 | [diff] [blame] | 523 | struct vfsmount *lookup_mnt(struct path *path) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 524 | { |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 525 | struct mount *child_mnt; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 526 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 527 | br_read_lock(&vfsmount_lock); |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 528 | child_mnt = __lookup_mnt(path->mnt, path->dentry, 1); |
| 529 | if (child_mnt) { |
| 530 | mnt_add_count(child_mnt, 1); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 531 | br_read_unlock(&vfsmount_lock); |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 532 | return &child_mnt->mnt; |
| 533 | } else { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 534 | br_read_unlock(&vfsmount_lock); |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 535 | return NULL; |
| 536 | } |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 537 | } |
| 538 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 539 | static inline int check_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 540 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 541 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 542 | } |
| 543 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 544 | /* |
| 545 | * vfsmount lock must be held for write |
| 546 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 547 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 548 | { |
| 549 | if (ns) { |
| 550 | ns->event = ++event; |
| 551 | wake_up_interruptible(&ns->poll); |
| 552 | } |
| 553 | } |
| 554 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 555 | /* |
| 556 | * vfsmount lock must be held for write |
| 557 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 558 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 559 | { |
| 560 | if (ns && ns->event != event) { |
| 561 | ns->event = event; |
| 562 | wake_up_interruptible(&ns->poll); |
| 563 | } |
| 564 | } |
| 565 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 566 | /* |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 567 | * Clear dentry's mounted state if it has no remaining mounts. |
| 568 | * vfsmount_lock must be held for write. |
| 569 | */ |
Al Viro | aa0a4cf | 2011-11-24 19:31:36 -0500 | [diff] [blame] | 570 | static void dentry_reset_mounted(struct dentry *dentry) |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 571 | { |
| 572 | unsigned u; |
| 573 | |
| 574 | for (u = 0; u < HASH_SIZE; u++) { |
Al Viro | d5e50f7 | 2011-11-24 20:58:57 -0500 | [diff] [blame] | 575 | struct mount *p; |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 576 | |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 577 | list_for_each_entry(p, &mount_hashtable[u], mnt_hash) { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 578 | if (p->mnt_mountpoint == dentry) |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 579 | return; |
| 580 | } |
| 581 | } |
| 582 | spin_lock(&dentry->d_lock); |
| 583 | dentry->d_flags &= ~DCACHE_MOUNTED; |
| 584 | spin_unlock(&dentry->d_lock); |
| 585 | } |
| 586 | |
| 587 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 588 | * vfsmount lock must be held for write |
| 589 | */ |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 590 | static void detach_mnt(struct mount *mnt, struct path *old_path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 591 | { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 592 | old_path->dentry = mnt->mnt_mountpoint; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 593 | old_path->mnt = &mnt->mnt_parent->mnt; |
| 594 | mnt->mnt_parent = mnt; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 595 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 596 | list_del_init(&mnt->mnt_child); |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 597 | list_del_init(&mnt->mnt_hash); |
Al Viro | aa0a4cf | 2011-11-24 19:31:36 -0500 | [diff] [blame] | 598 | dentry_reset_mounted(old_path->dentry); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 599 | } |
| 600 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 601 | /* |
| 602 | * vfsmount lock must be held for write |
| 603 | */ |
Al Viro | 14cf1fa | 2011-11-25 00:01:17 -0500 | [diff] [blame] | 604 | void mnt_set_mountpoint(struct mount *mnt, struct dentry *dentry, |
Al Viro | 44d964d6 | 2011-11-24 21:28:22 -0500 | [diff] [blame] | 605 | struct mount *child_mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 606 | { |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 607 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 608 | child_mnt->mnt_mountpoint = dget(dentry); |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 609 | child_mnt->mnt_parent = mnt; |
Nick Piggin | 5f57cbc | 2011-01-07 17:49:54 +1100 | [diff] [blame] | 610 | spin_lock(&dentry->d_lock); |
| 611 | dentry->d_flags |= DCACHE_MOUNTED; |
| 612 | spin_unlock(&dentry->d_lock); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 613 | } |
| 614 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 615 | /* |
| 616 | * vfsmount lock must be held for write |
| 617 | */ |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 618 | static void attach_mnt(struct mount *mnt, struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 619 | { |
Al Viro | 14cf1fa | 2011-11-25 00:01:17 -0500 | [diff] [blame] | 620 | mnt_set_mountpoint(real_mount(path->mnt), path->dentry, mnt); |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 621 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 622 | hash(path->mnt, path->dentry)); |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 623 | list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 624 | } |
| 625 | |
| 626 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 627 | * vfsmount lock must be held for write |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 628 | */ |
Al Viro | 4b2619a | 2011-11-24 19:47:15 -0500 | [diff] [blame] | 629 | static void commit_tree(struct mount *mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 630 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 631 | struct mount *parent = mnt->mnt_parent; |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 632 | struct mount *m; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 633 | LIST_HEAD(head); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 634 | struct mnt_namespace *n = parent->mnt_ns; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 635 | |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 636 | BUG_ON(parent == mnt); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 637 | |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 638 | list_add_tail(&head, &mnt->mnt_list); |
Al Viro | d9eb504 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 639 | list_for_each_entry(m, &head, mnt_list) |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 640 | m->mnt_ns = n; |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 641 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 642 | list_splice(&head, n->list.prev); |
| 643 | |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 644 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 645 | hash(&parent->mnt, mnt->mnt_mountpoint)); |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 646 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 647 | touch_mnt_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 648 | } |
| 649 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 650 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 651 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 652 | struct list_head *next = p->mnt_mounts.next; |
| 653 | if (next == &p->mnt_mounts) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 654 | while (1) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 655 | if (p == root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 656 | return NULL; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 657 | next = p->mnt_child.next; |
| 658 | if (next != &p->mnt_parent->mnt_mounts) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 659 | break; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 660 | p = p->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 661 | } |
| 662 | } |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 663 | return list_entry(next, struct mount, mnt_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 664 | } |
| 665 | |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 666 | static struct mount *skip_mnt_tree(struct mount *p) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 667 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 668 | struct list_head *prev = p->mnt_mounts.prev; |
| 669 | while (prev != &p->mnt_mounts) { |
| 670 | p = list_entry(prev, struct mount, mnt_child); |
| 671 | prev = p->mnt_mounts.prev; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 672 | } |
| 673 | return p; |
| 674 | } |
| 675 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 676 | struct vfsmount * |
| 677 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) |
| 678 | { |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 679 | struct mount *mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 680 | struct dentry *root; |
| 681 | |
| 682 | if (!type) |
| 683 | return ERR_PTR(-ENODEV); |
| 684 | |
| 685 | mnt = alloc_vfsmnt(name); |
| 686 | if (!mnt) |
| 687 | return ERR_PTR(-ENOMEM); |
| 688 | |
| 689 | if (flags & MS_KERNMOUNT) |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 690 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 691 | |
| 692 | root = mount_fs(type, flags, name, data); |
| 693 | if (IS_ERR(root)) { |
| 694 | free_vfsmnt(mnt); |
| 695 | return ERR_CAST(root); |
| 696 | } |
| 697 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 698 | mnt->mnt.mnt_root = root; |
| 699 | mnt->mnt.mnt_sb = root->d_sb; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 700 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 701 | mnt->mnt_parent = mnt; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 702 | br_write_lock(&vfsmount_lock); |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 703 | list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 704 | br_write_unlock(&vfsmount_lock); |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 705 | return &mnt->mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 706 | } |
| 707 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
| 708 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 709 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 710 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 711 | { |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 712 | struct super_block *sb = old->mnt.mnt_sb; |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 713 | struct mount *mnt; |
| 714 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 715 | |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 716 | mnt = alloc_vfsmnt(old->mnt_devname); |
| 717 | if (!mnt) |
| 718 | return ERR_PTR(-ENOMEM); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 719 | |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 720 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
| 721 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 722 | else |
| 723 | mnt->mnt_group_id = old->mnt_group_id; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 724 | |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 725 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 726 | err = mnt_alloc_group_id(mnt); |
| 727 | if (err) |
| 728 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 729 | } |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 730 | |
| 731 | mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; |
| 732 | atomic_inc(&sb->s_active); |
| 733 | mnt->mnt.mnt_sb = sb; |
| 734 | mnt->mnt.mnt_root = dget(root); |
| 735 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 736 | mnt->mnt_parent = mnt; |
| 737 | br_write_lock(&vfsmount_lock); |
| 738 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
| 739 | br_write_unlock(&vfsmount_lock); |
| 740 | |
| 741 | if (flag & CL_SLAVE) { |
| 742 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 743 | mnt->mnt_master = old; |
| 744 | CLEAR_MNT_SHARED(mnt); |
| 745 | } else if (!(flag & CL_PRIVATE)) { |
| 746 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
| 747 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 748 | if (IS_MNT_SLAVE(old)) |
| 749 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 750 | mnt->mnt_master = old->mnt_master; |
| 751 | } |
| 752 | if (flag & CL_MAKE_SHARED) |
| 753 | set_mnt_shared(mnt); |
| 754 | |
| 755 | /* stick the duplicate mount on the same expiry list |
| 756 | * as the original if that was on one */ |
| 757 | if (flag & CL_EXPIRE) { |
| 758 | if (!list_empty(&old->mnt_expire)) |
| 759 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 760 | } |
| 761 | |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 762 | return mnt; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 763 | |
| 764 | out_free: |
| 765 | free_vfsmnt(mnt); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 766 | return ERR_PTR(err); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 767 | } |
| 768 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 769 | static inline void mntfree(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 770 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 771 | struct vfsmount *m = &mnt->mnt; |
| 772 | struct super_block *sb = m->mnt_sb; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 773 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 774 | /* |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 775 | * This probably indicates that somebody messed |
| 776 | * up a mnt_want/drop_write() pair. If this |
| 777 | * happens, the filesystem was probably unable |
| 778 | * to make r/w->r/o transitions. |
| 779 | */ |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 780 | /* |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 781 | * The locking used to deal with mnt_count decrement provides barriers, |
| 782 | * so mnt_get_writers() below is safe. |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 783 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 784 | WARN_ON(mnt_get_writers(mnt)); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 785 | fsnotify_vfsmount_delete(m); |
| 786 | dput(m->mnt_root); |
| 787 | free_vfsmnt(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 788 | deactivate_super(sb); |
| 789 | } |
| 790 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 791 | static void mntput_no_expire(struct mount *mnt) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 792 | { |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 793 | put_again: |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 794 | #ifdef CONFIG_SMP |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 795 | br_read_lock(&vfsmount_lock); |
Al Viro | d9eb504 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 796 | if (likely(mnt->mnt_ns)) { |
| 797 | /* shouldn't be the last one */ |
Al Viro | aa9c0e0 | 2011-11-23 19:04:52 -0500 | [diff] [blame] | 798 | mnt_add_count(mnt, -1); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 799 | br_read_unlock(&vfsmount_lock); |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 800 | return; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 801 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 802 | br_read_unlock(&vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 803 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 804 | br_write_lock(&vfsmount_lock); |
Al Viro | aa9c0e0 | 2011-11-23 19:04:52 -0500 | [diff] [blame] | 805 | mnt_add_count(mnt, -1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 806 | if (mnt_get_count(mnt)) { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 807 | br_write_unlock(&vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 808 | return; |
| 809 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 810 | #else |
Al Viro | aa9c0e0 | 2011-11-23 19:04:52 -0500 | [diff] [blame] | 811 | mnt_add_count(mnt, -1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 812 | if (likely(mnt_get_count(mnt))) |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 813 | return; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 814 | br_write_lock(&vfsmount_lock); |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 815 | #endif |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 816 | if (unlikely(mnt->mnt_pinned)) { |
| 817 | mnt_add_count(mnt, mnt->mnt_pinned + 1); |
| 818 | mnt->mnt_pinned = 0; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 819 | br_write_unlock(&vfsmount_lock); |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 820 | acct_auto_close_mnt(&mnt->mnt); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 821 | goto put_again; |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 822 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 823 | |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 824 | list_del(&mnt->mnt_instance); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 825 | br_write_unlock(&vfsmount_lock); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 826 | mntfree(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 827 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 828 | |
| 829 | void mntput(struct vfsmount *mnt) |
| 830 | { |
| 831 | if (mnt) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 832 | struct mount *m = real_mount(mnt); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 833 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 834 | if (unlikely(m->mnt_expiry_mark)) |
| 835 | m->mnt_expiry_mark = 0; |
| 836 | mntput_no_expire(m); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 837 | } |
| 838 | } |
| 839 | EXPORT_SYMBOL(mntput); |
| 840 | |
| 841 | struct vfsmount *mntget(struct vfsmount *mnt) |
| 842 | { |
| 843 | if (mnt) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 844 | mnt_add_count(real_mount(mnt), 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 845 | return mnt; |
| 846 | } |
| 847 | EXPORT_SYMBOL(mntget); |
| 848 | |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 849 | void mnt_pin(struct vfsmount *mnt) |
| 850 | { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 851 | br_write_lock(&vfsmount_lock); |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 852 | real_mount(mnt)->mnt_pinned++; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 853 | br_write_unlock(&vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 854 | } |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 855 | EXPORT_SYMBOL(mnt_pin); |
| 856 | |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 857 | void mnt_unpin(struct vfsmount *m) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 858 | { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 859 | struct mount *mnt = real_mount(m); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 860 | br_write_lock(&vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 861 | if (mnt->mnt_pinned) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 862 | mnt_add_count(mnt, 1); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 863 | mnt->mnt_pinned--; |
| 864 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 865 | br_write_unlock(&vfsmount_lock); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 866 | } |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 867 | EXPORT_SYMBOL(mnt_unpin); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 868 | |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 869 | static inline void mangle(struct seq_file *m, const char *s) |
| 870 | { |
| 871 | seq_escape(m, s, " \t\n\\"); |
| 872 | } |
| 873 | |
| 874 | /* |
| 875 | * Simple .show_options callback for filesystems which don't want to |
| 876 | * implement more complex mount option showing. |
| 877 | * |
| 878 | * See also save_mount_options(). |
| 879 | */ |
Al Viro | 34c80b1 | 2011-12-08 21:32:45 -0500 | [diff] [blame] | 880 | int generic_show_options(struct seq_file *m, struct dentry *root) |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 881 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 882 | const char *options; |
| 883 | |
| 884 | rcu_read_lock(); |
Al Viro | 34c80b1 | 2011-12-08 21:32:45 -0500 | [diff] [blame] | 885 | options = rcu_dereference(root->d_sb->s_options); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 886 | |
| 887 | if (options != NULL && options[0]) { |
| 888 | seq_putc(m, ','); |
| 889 | mangle(m, options); |
| 890 | } |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 891 | rcu_read_unlock(); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 892 | |
| 893 | return 0; |
| 894 | } |
| 895 | EXPORT_SYMBOL(generic_show_options); |
| 896 | |
| 897 | /* |
| 898 | * If filesystem uses generic_show_options(), this function should be |
| 899 | * called from the fill_super() callback. |
| 900 | * |
| 901 | * The .remount_fs callback usually needs to be handled in a special |
| 902 | * way, to make sure, that previous options are not overwritten if the |
| 903 | * remount fails. |
| 904 | * |
| 905 | * Also note, that if the filesystem's .remount_fs function doesn't |
| 906 | * reset all options to their default value, but changes only newly |
| 907 | * given options, then the displayed options will not reflect reality |
| 908 | * any more. |
| 909 | */ |
| 910 | void save_mount_options(struct super_block *sb, char *options) |
| 911 | { |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 912 | BUG_ON(sb->s_options); |
| 913 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); |
Miklos Szeredi | b3b304a | 2008-02-08 04:21:35 -0800 | [diff] [blame] | 914 | } |
| 915 | EXPORT_SYMBOL(save_mount_options); |
| 916 | |
Al Viro | 2a32ceb | 2009-05-08 16:05:57 -0400 | [diff] [blame] | 917 | void replace_mount_options(struct super_block *sb, char *options) |
| 918 | { |
| 919 | char *old = sb->s_options; |
| 920 | rcu_assign_pointer(sb->s_options, options); |
| 921 | if (old) { |
| 922 | synchronize_rcu(); |
| 923 | kfree(old); |
| 924 | } |
| 925 | } |
| 926 | EXPORT_SYMBOL(replace_mount_options); |
| 927 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 928 | #ifdef CONFIG_PROC_FS |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 929 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 930 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 931 | { |
Al Viro | 50a876b | 2012-06-09 01:16:59 -0400 | [diff] [blame] | 932 | struct proc_mounts *p = proc_mounts(m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 933 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 934 | down_read(&namespace_sem); |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 935 | return seq_list_start(&p->ns->list, *pos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 936 | } |
| 937 | |
| 938 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 939 | { |
Al Viro | 50a876b | 2012-06-09 01:16:59 -0400 | [diff] [blame] | 940 | struct proc_mounts *p = proc_mounts(m); |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 941 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 942 | return seq_list_next(v, &p->ns->list, pos); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 943 | } |
| 944 | |
| 945 | static void m_stop(struct seq_file *m, void *v) |
| 946 | { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 947 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | } |
| 949 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 950 | static int m_show(struct seq_file *m, void *v) |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 951 | { |
Al Viro | 50a876b | 2012-06-09 01:16:59 -0400 | [diff] [blame] | 952 | struct proc_mounts *p = proc_mounts(m); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 953 | struct mount *r = list_entry(v, struct mount, mnt_list); |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 954 | return p->show(m, &r->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 955 | } |
| 956 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 957 | const struct seq_operations mounts_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 958 | .start = m_start, |
| 959 | .next = m_next, |
| 960 | .stop = m_stop, |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 961 | .show = m_show, |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 962 | }; |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 963 | #endif /* CONFIG_PROC_FS */ |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 964 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 965 | /** |
| 966 | * may_umount_tree - check if a mount tree is busy |
| 967 | * @mnt: root of mount tree |
| 968 | * |
| 969 | * This is called to check if a tree of mounts has any |
| 970 | * open files, pwds, chroots or sub mounts that are |
| 971 | * busy. |
| 972 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 973 | int may_umount_tree(struct vfsmount *m) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 974 | { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 975 | struct mount *mnt = real_mount(m); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 976 | int actual_refs = 0; |
| 977 | int minimum_refs = 0; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 978 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 979 | BUG_ON(!m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 980 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 981 | /* write lock needed for mnt_get_count */ |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 982 | br_write_lock(&vfsmount_lock); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 983 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 984 | actual_refs += mnt_get_count(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 985 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 986 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 987 | br_write_unlock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 988 | |
| 989 | if (actual_refs > minimum_refs) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 990 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 991 | |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 992 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 993 | } |
| 994 | |
| 995 | EXPORT_SYMBOL(may_umount_tree); |
| 996 | |
| 997 | /** |
| 998 | * may_umount - check if a mount point is busy |
| 999 | * @mnt: root of mount |
| 1000 | * |
| 1001 | * This is called to check if a mount point has any |
| 1002 | * open files, pwds, chroots or sub mounts. If the |
| 1003 | * mount has sub mounts this will return busy |
| 1004 | * regardless of whether the sub mounts are busy. |
| 1005 | * |
| 1006 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 1007 | * give false negatives. The main reason why it's here is that we need |
| 1008 | * a non-destructive way to look for easily umountable filesystems. |
| 1009 | */ |
| 1010 | int may_umount(struct vfsmount *mnt) |
| 1011 | { |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1012 | int ret = 1; |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1013 | down_read(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1014 | br_write_lock(&vfsmount_lock); |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1015 | if (propagate_mount_busy(real_mount(mnt), 2)) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1016 | ret = 0; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1017 | br_write_unlock(&vfsmount_lock); |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1018 | up_read(&namespace_sem); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1019 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1020 | } |
| 1021 | |
| 1022 | EXPORT_SYMBOL(may_umount); |
| 1023 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1024 | void release_mounts(struct list_head *head) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1025 | { |
Al Viro | d5e50f7 | 2011-11-24 20:58:57 -0500 | [diff] [blame] | 1026 | struct mount *mnt; |
Miklos Szeredi | bf066c7 | 2006-01-08 01:03:19 -0800 | [diff] [blame] | 1027 | while (!list_empty(head)) { |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 1028 | mnt = list_first_entry(head, struct mount, mnt_hash); |
| 1029 | list_del_init(&mnt->mnt_hash); |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1030 | if (mnt_has_parent(mnt)) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1031 | struct dentry *dentry; |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1032 | struct mount *m; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1033 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1034 | br_write_lock(&vfsmount_lock); |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1035 | dentry = mnt->mnt_mountpoint; |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1036 | m = mnt->mnt_parent; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1037 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1038 | mnt->mnt_parent = mnt; |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1039 | m->mnt_ghosts--; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1040 | br_write_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1041 | dput(dentry); |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1042 | mntput(&m->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1043 | } |
Al Viro | d5e50f7 | 2011-11-24 20:58:57 -0500 | [diff] [blame] | 1044 | mntput(&mnt->mnt); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1045 | } |
| 1046 | } |
| 1047 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1048 | /* |
| 1049 | * vfsmount lock must be held for write |
| 1050 | * namespace_sem must be held for write |
| 1051 | */ |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 1052 | void umount_tree(struct mount *mnt, int propagate, struct list_head *kill) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1053 | { |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1054 | LIST_HEAD(tmp_list); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1055 | struct mount *p; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1056 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1057 | for (p = mnt; p; p = next_mnt(p, mnt)) |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 1058 | list_move(&p->mnt_hash, &tmp_list); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1059 | |
Al Viro | 6722908 | 2014-08-18 15:09:26 -0400 | [diff] [blame] | 1060 | list_for_each_entry(p, &tmp_list, mnt_hash) |
| 1061 | list_del_init(&p->mnt_child); |
| 1062 | |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1063 | if (propagate) |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1064 | propagate_umount(&tmp_list); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1065 | |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 1066 | list_for_each_entry(p, &tmp_list, mnt_hash) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1067 | list_del_init(&p->mnt_expire); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1068 | list_del_init(&p->mnt_list); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1069 | __touch_mnt_namespace(p->mnt_ns); |
| 1070 | p->mnt_ns = NULL; |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1071 | if (mnt_has_parent(p)) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1072 | p->mnt_parent->mnt_ghosts++; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1073 | dentry_reset_mounted(p->mnt_mountpoint); |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1074 | } |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1075 | change_mnt_propagation(p, MS_PRIVATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1076 | } |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1077 | list_splice(&tmp_list, kill); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1078 | } |
| 1079 | |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 1080 | static void shrink_submounts(struct mount *mnt, struct list_head *umounts); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1081 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1082 | static int do_umount(struct mount *mnt, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1083 | { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1084 | struct super_block *sb = mnt->mnt.mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1085 | int retval; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1086 | LIST_HEAD(umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1087 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1088 | retval = security_sb_umount(&mnt->mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1089 | if (retval) |
| 1090 | return retval; |
| 1091 | |
| 1092 | /* |
| 1093 | * Allow userspace to request a mountpoint be expired rather than |
| 1094 | * unmounting unconditionally. Unmount only happens if: |
| 1095 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 1096 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 1097 | */ |
| 1098 | if (flags & MNT_EXPIRE) { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1099 | if (&mnt->mnt == current->fs->root.mnt || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1100 | flags & (MNT_FORCE | MNT_DETACH)) |
| 1101 | return -EINVAL; |
| 1102 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1103 | /* |
| 1104 | * probably don't strictly need the lock here if we examined |
| 1105 | * all race cases, but it's a slowpath. |
| 1106 | */ |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1107 | br_write_lock(&vfsmount_lock); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1108 | if (mnt_get_count(mnt) != 2) { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1109 | br_write_unlock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1110 | return -EBUSY; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1111 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1112 | br_write_unlock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1113 | |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1114 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1115 | return -EAGAIN; |
| 1116 | } |
| 1117 | |
| 1118 | /* |
| 1119 | * If we may have to abort operations to get out of this |
| 1120 | * mount, and they will themselves hold resources we must |
| 1121 | * allow the fs to do things. In the Unix tradition of |
| 1122 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 1123 | * might fail to complete on the first run through as other tasks |
| 1124 | * must return, and the like. Thats for the mount program to worry |
| 1125 | * about for the moment. |
| 1126 | */ |
| 1127 | |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1128 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1129 | sb->s_op->umount_begin(sb); |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1130 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1131 | |
| 1132 | /* |
| 1133 | * No sense to grab the lock for this test, but test itself looks |
| 1134 | * somewhat bogus. Suggestions for better replacement? |
| 1135 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1136 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1137 | * Actually it makes sense, especially if rootfs would contain a |
| 1138 | * /reboot - static binary that would close all descriptors and |
| 1139 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1140 | */ |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1141 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1142 | /* |
| 1143 | * Special case for "unmounting" root ... |
| 1144 | * we just try to remount it readonly. |
| 1145 | */ |
| 1146 | down_write(&sb->s_umount); |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 1147 | if (!(sb->s_flags & MS_RDONLY)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1148 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1149 | up_write(&sb->s_umount); |
| 1150 | return retval; |
| 1151 | } |
| 1152 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1153 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1154 | br_write_lock(&vfsmount_lock); |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 1155 | event++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1156 | |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1157 | if (!(flags & MNT_DETACH)) |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1158 | shrink_submounts(mnt, &umount_list); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1159 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1160 | retval = -EBUSY; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1161 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1162 | if (!list_empty(&mnt->mnt_list)) |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1163 | umount_tree(mnt, 1, &umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1164 | retval = 0; |
| 1165 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1166 | br_write_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1167 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1168 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1169 | return retval; |
| 1170 | } |
| 1171 | |
| 1172 | /* |
| 1173 | * Now umount can handle mount points as well as block devices. |
| 1174 | * This is important for filesystems which use unnamed block devices. |
| 1175 | * |
| 1176 | * We now support a flag for forced unmount like the other 'big iron' |
| 1177 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD |
| 1178 | */ |
| 1179 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1180 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1181 | { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1182 | struct path path; |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1183 | struct mount *mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1184 | int retval; |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1185 | int lookup_flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1186 | |
Miklos Szeredi | db1f05b | 2010-02-10 12:15:53 +0100 | [diff] [blame] | 1187 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
| 1188 | return -EINVAL; |
| 1189 | |
| 1190 | if (!(flags & UMOUNT_NOFOLLOW)) |
| 1191 | lookup_flags |= LOOKUP_FOLLOW; |
| 1192 | |
| 1193 | retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1194 | if (retval) |
| 1195 | goto out; |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1196 | mnt = real_mount(path.mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1197 | retval = -EINVAL; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1198 | if (path.dentry != path.mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1199 | goto dput_and_out; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1200 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1201 | goto dput_and_out; |
| 1202 | |
| 1203 | retval = -EPERM; |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1204 | if (!ns_capable(mnt->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1205 | goto dput_and_out; |
| 1206 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1207 | retval = do_umount(mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1208 | dput_and_out: |
Jan Blunck | 429731b | 2008-02-14 19:34:31 -0800 | [diff] [blame] | 1209 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 1210 | dput(path.dentry); |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1211 | mntput_no_expire(mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1212 | out: |
| 1213 | return retval; |
| 1214 | } |
| 1215 | |
| 1216 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1217 | |
| 1218 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1219 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1220 | */ |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1221 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1222 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1223 | return sys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1224 | } |
| 1225 | |
| 1226 | #endif |
| 1227 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1228 | static int mount_is_safe(struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1229 | { |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1230 | if (ns_capable(real_mount(path->mnt)->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1231 | return 0; |
| 1232 | return -EPERM; |
| 1233 | #ifdef notyet |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1234 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1235 | return -EPERM; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1236 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
David Howells | da9592e | 2008-11-14 10:39:05 +1100 | [diff] [blame] | 1237 | if (current_uid() != path->dentry->d_inode->i_uid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1238 | return -EPERM; |
| 1239 | } |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1240 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1241 | return -EPERM; |
| 1242 | return 0; |
| 1243 | #endif |
| 1244 | } |
| 1245 | |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 1246 | static bool mnt_ns_loop(struct path *path) |
| 1247 | { |
| 1248 | /* Could bind mounting the mount namespace inode cause a |
| 1249 | * mount namespace loop? |
| 1250 | */ |
| 1251 | struct inode *inode = path->dentry->d_inode; |
| 1252 | struct proc_inode *ei; |
| 1253 | struct mnt_namespace *mnt_ns; |
| 1254 | |
| 1255 | if (!proc_ns_inode(inode)) |
| 1256 | return false; |
| 1257 | |
| 1258 | ei = PROC_I(inode); |
| 1259 | if (ei->ns_ops != &mntns_operations) |
| 1260 | return false; |
| 1261 | |
| 1262 | mnt_ns = ei->ns; |
| 1263 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
| 1264 | } |
| 1265 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1266 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1267 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1268 | { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1269 | struct mount *res, *p, *q, *r; |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1270 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1271 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1272 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1273 | return ERR_PTR(-EINVAL); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1274 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1275 | res = q = clone_mnt(mnt, dentry, flag); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1276 | if (IS_ERR(q)) |
| 1277 | return q; |
| 1278 | |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1279 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1280 | |
| 1281 | p = mnt; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1282 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1283 | struct mount *s; |
Jan Blunck | 7ec02ef | 2008-04-29 00:59:40 -0700 | [diff] [blame] | 1284 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1285 | continue; |
| 1286 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1287 | for (s = r; s; s = next_mnt(s, r)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1288 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1289 | s = skip_mnt_tree(s); |
| 1290 | continue; |
| 1291 | } |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1292 | while (p != s->mnt_parent) { |
| 1293 | p = p->mnt_parent; |
| 1294 | q = q->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1295 | } |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1296 | p = s; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1297 | path.mnt = &q->mnt; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1298 | path.dentry = p->mnt_mountpoint; |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1299 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1300 | if (IS_ERR(q)) |
| 1301 | goto out; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1302 | br_write_lock(&vfsmount_lock); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1303 | list_add_tail(&q->mnt_list, &res->mnt_list); |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1304 | attach_mnt(q, &path); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1305 | br_write_unlock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1306 | } |
| 1307 | } |
| 1308 | return res; |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1309 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1310 | if (res) { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1311 | LIST_HEAD(umount_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1312 | br_write_lock(&vfsmount_lock); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 1313 | umount_tree(res, 0, &umount_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1314 | br_write_unlock(&vfsmount_lock); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1315 | release_mounts(&umount_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1316 | } |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1317 | return q; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1318 | } |
| 1319 | |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1320 | /* Caller should check returned pointer for errors */ |
| 1321 | |
Al Viro | 589ff87 | 2009-04-18 03:28:19 -0400 | [diff] [blame] | 1322 | struct vfsmount *collect_mounts(struct path *path) |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1323 | { |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1324 | struct mount *tree; |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1325 | down_write(&namespace_sem); |
Eric W. Biederman | 85d13c3 | 2015-01-07 14:28:26 -0600 | [diff] [blame] | 1326 | if (!check_mnt(real_mount(path->mnt))) |
| 1327 | tree = ERR_PTR(-EINVAL); |
| 1328 | else |
| 1329 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1330 | CL_COPY_ALL | CL_PRIVATE); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1331 | up_write(&namespace_sem); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1332 | if (IS_ERR(tree)) |
| 1333 | return NULL; |
| 1334 | return &tree->mnt; |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1335 | } |
| 1336 | |
| 1337 | void drop_collected_mounts(struct vfsmount *mnt) |
| 1338 | { |
| 1339 | LIST_HEAD(umount_list); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1340 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1341 | br_write_lock(&vfsmount_lock); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 1342 | umount_tree(real_mount(mnt), 0, &umount_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1343 | br_write_unlock(&vfsmount_lock); |
Al Viro | 1a60a28 | 2008-03-22 16:19:49 -0400 | [diff] [blame] | 1344 | up_write(&namespace_sem); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 1345 | release_mounts(&umount_list); |
| 1346 | } |
| 1347 | |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1348 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
| 1349 | struct vfsmount *root) |
| 1350 | { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1351 | struct mount *mnt; |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1352 | int res = f(root, arg); |
| 1353 | if (res) |
| 1354 | return res; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1355 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
| 1356 | res = f(&mnt->mnt, arg); |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 1357 | if (res) |
| 1358 | return res; |
| 1359 | } |
| 1360 | return 0; |
| 1361 | } |
| 1362 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1363 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1364 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1365 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1366 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1367 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1368 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1369 | mnt_release_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1370 | } |
| 1371 | } |
| 1372 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1373 | static int invent_group_ids(struct mount *mnt, bool recurse) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1374 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1375 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1376 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1377 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1378 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1379 | int err = mnt_alloc_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1380 | if (err) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1381 | cleanup_group_ids(mnt, p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1382 | return err; |
| 1383 | } |
| 1384 | } |
| 1385 | } |
| 1386 | |
| 1387 | return 0; |
| 1388 | } |
| 1389 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1390 | /* |
| 1391 | * @source_mnt : mount tree to be attached |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1392 | * @nd : place the mount tree @source_mnt is attached |
| 1393 | * @parent_nd : if non-null, detach the source_mnt from its parent and |
| 1394 | * store the parent mount and mountpoint dentry. |
| 1395 | * (done when source_mnt is moved) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1396 | * |
| 1397 | * NOTE: in the table below explains the semantics when a source mount |
| 1398 | * 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] | 1399 | * --------------------------------------------------------------------------- |
| 1400 | * | BIND MOUNT OPERATION | |
| 1401 | * |************************************************************************** |
| 1402 | * | source-->| shared | private | slave | unbindable | |
| 1403 | * | dest | | | | | |
| 1404 | * | | | | | | | |
| 1405 | * | v | | | | | |
| 1406 | * |************************************************************************** |
| 1407 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 1408 | * | | | | | | |
| 1409 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 1410 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1411 | * A bind operation clones the source mount and mounts the clone on the |
| 1412 | * destination mount. |
| 1413 | * |
| 1414 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 1415 | * tree of the destination mount and the cloned mount is added to |
| 1416 | * the peer group of the source mount. |
| 1417 | * (+) the cloned mount is created under the destination mount and is marked |
| 1418 | * as shared. The cloned mount is added to the peer group of the source |
| 1419 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1420 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 1421 | * of the destination mount and the cloned mount is made slave |
| 1422 | * of the same master as that of the source mount. The cloned mount |
| 1423 | * is marked as 'shared and slave'. |
| 1424 | * (*) the cloned mount is made a slave of the same master as that of the |
| 1425 | * source mount. |
| 1426 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1427 | * --------------------------------------------------------------------------- |
| 1428 | * | MOVE MOUNT OPERATION | |
| 1429 | * |************************************************************************** |
| 1430 | * | source-->| shared | private | slave | unbindable | |
| 1431 | * | dest | | | | | |
| 1432 | * | | | | | | | |
| 1433 | * | v | | | | | |
| 1434 | * |************************************************************************** |
| 1435 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 1436 | * | | | | | | |
| 1437 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 1438 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1439 | * |
| 1440 | * (+) the mount is moved to the destination. And is then propagated to |
| 1441 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1442 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 1443 | * (+++) the mount is moved to the destination and is then propagated to |
| 1444 | * all the mounts belonging to the destination mount's propagation tree. |
| 1445 | * the mount is marked as 'shared and slave'. |
| 1446 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1447 | * |
| 1448 | * if the source mount is a tree, the operations explained above is |
| 1449 | * applied to each mount in the tree. |
| 1450 | * Must be called without spinlocks held, since this function can sleep |
| 1451 | * in allocations. |
| 1452 | */ |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1453 | static int attach_recursive_mnt(struct mount *source_mnt, |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1454 | struct path *path, struct path *parent_path) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1455 | { |
| 1456 | LIST_HEAD(tree_list); |
Al Viro | a8d56d8 | 2011-11-24 23:59:29 -0500 | [diff] [blame] | 1457 | struct mount *dest_mnt = real_mount(path->mnt); |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1458 | struct dentry *dest_dentry = path->dentry; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1459 | struct mount *child, *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1460 | int err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1461 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1462 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1463 | err = invent_group_ids(source_mnt, true); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1464 | if (err) |
| 1465 | goto out; |
| 1466 | } |
Al Viro | a8d56d8 | 2011-11-24 23:59:29 -0500 | [diff] [blame] | 1467 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1468 | if (err) |
| 1469 | goto out_cleanup_ids; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1470 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1471 | br_write_lock(&vfsmount_lock); |
Al Viro | df1a1ad | 2010-01-16 12:57:40 -0500 | [diff] [blame] | 1472 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1473 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1474 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1475 | set_mnt_shared(p); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1476 | } |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1477 | if (parent_path) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1478 | detach_mnt(source_mnt, parent_path); |
| 1479 | attach_mnt(source_mnt, path); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1480 | touch_mnt_namespace(source_mnt->mnt_ns); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1481 | } else { |
Al Viro | 14cf1fa | 2011-11-25 00:01:17 -0500 | [diff] [blame] | 1482 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1483 | commit_tree(source_mnt); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1484 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1485 | |
Al Viro | 1b8e556 | 2011-11-24 21:01:32 -0500 | [diff] [blame] | 1486 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
| 1487 | list_del_init(&child->mnt_hash); |
Al Viro | 4b2619a | 2011-11-24 19:47:15 -0500 | [diff] [blame] | 1488 | commit_tree(child); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1489 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1490 | br_write_unlock(&vfsmount_lock); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1491 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1492 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1493 | |
| 1494 | out_cleanup_ids: |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1495 | if (IS_MNT_SHARED(dest_mnt)) |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1496 | cleanup_group_ids(source_mnt, NULL); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1497 | out: |
| 1498 | return err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1499 | } |
| 1500 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1501 | static int lock_mount(struct path *path) |
| 1502 | { |
| 1503 | struct vfsmount *mnt; |
| 1504 | retry: |
| 1505 | mutex_lock(&path->dentry->d_inode->i_mutex); |
| 1506 | if (unlikely(cant_mount(path->dentry))) { |
| 1507 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
| 1508 | return -ENOENT; |
| 1509 | } |
| 1510 | down_write(&namespace_sem); |
| 1511 | mnt = lookup_mnt(path); |
| 1512 | if (likely(!mnt)) |
| 1513 | return 0; |
| 1514 | up_write(&namespace_sem); |
| 1515 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
| 1516 | path_put(path); |
| 1517 | path->mnt = mnt; |
| 1518 | path->dentry = dget(mnt->mnt_root); |
| 1519 | goto retry; |
| 1520 | } |
| 1521 | |
| 1522 | static void unlock_mount(struct path *path) |
| 1523 | { |
| 1524 | up_write(&namespace_sem); |
| 1525 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
| 1526 | } |
| 1527 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1528 | static int graft_tree(struct mount *mnt, struct path *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1529 | { |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1530 | if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1531 | return -EINVAL; |
| 1532 | |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 1533 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1534 | S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1535 | return -ENOTDIR; |
| 1536 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1537 | if (d_unlinked(path->dentry)) |
| 1538 | return -ENOENT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1539 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1540 | return attach_recursive_mnt(mnt, path, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1541 | } |
| 1542 | |
| 1543 | /* |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1544 | * Sanity check the flags to change_mnt_propagation. |
| 1545 | */ |
| 1546 | |
| 1547 | static int flags_to_propagation_type(int flags) |
| 1548 | { |
Roman Borisov | 7c6e984 | 2011-05-25 16:26:48 -0700 | [diff] [blame] | 1549 | int type = flags & ~(MS_REC | MS_SILENT); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1550 | |
| 1551 | /* Fail if any non-propagation flags are set */ |
| 1552 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 1553 | return 0; |
| 1554 | /* Only one propagation flag should be set */ |
| 1555 | if (!is_power_of_2(type)) |
| 1556 | return 0; |
| 1557 | return type; |
| 1558 | } |
| 1559 | |
| 1560 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1561 | * recursively change the type of the mountpoint. |
| 1562 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1563 | static int do_change_type(struct path *path, int flag) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1564 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1565 | struct mount *m; |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 1566 | struct mount *mnt = real_mount(path->mnt); |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1567 | int recurse = flag & MS_REC; |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1568 | int type; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1569 | int err = 0; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1570 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1571 | if (!ns_capable(mnt->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
Miklos Szeredi | ee6f958 | 2007-05-08 00:30:40 -0700 | [diff] [blame] | 1572 | return -EPERM; |
| 1573 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1574 | if (path->dentry != path->mnt->mnt_root) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1575 | return -EINVAL; |
| 1576 | |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 1577 | type = flags_to_propagation_type(flag); |
| 1578 | if (!type) |
| 1579 | return -EINVAL; |
| 1580 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1581 | down_write(&namespace_sem); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1582 | if (type == MS_SHARED) { |
| 1583 | err = invent_group_ids(mnt, recurse); |
| 1584 | if (err) |
| 1585 | goto out_unlock; |
| 1586 | } |
| 1587 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1588 | br_write_lock(&vfsmount_lock); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1589 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1590 | change_mnt_propagation(m, type); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1591 | br_write_unlock(&vfsmount_lock); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1592 | |
| 1593 | out_unlock: |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1594 | up_write(&namespace_sem); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1595 | return err; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 1596 | } |
| 1597 | |
| 1598 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1599 | * do loopback mount. |
| 1600 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1601 | static int do_loopback(struct path *path, char *old_name, |
Eric Sandeen | 2dafe1c | 2008-02-08 04:22:12 -0800 | [diff] [blame] | 1602 | int recurse) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1603 | { |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1604 | LIST_HEAD(umount_list); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1605 | struct path old_path; |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1606 | struct mount *mnt = NULL, *old; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1607 | int err = mount_is_safe(path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1608 | if (err) |
| 1609 | return err; |
| 1610 | if (!old_name || !*old_name) |
| 1611 | return -EINVAL; |
Trond Myklebust | 815d405 | 2011-09-26 20:36:09 -0400 | [diff] [blame] | 1612 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1613 | if (err) |
| 1614 | return err; |
| 1615 | |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 1616 | err = -EINVAL; |
| 1617 | if (mnt_ns_loop(&old_path)) |
| 1618 | goto out; |
| 1619 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1620 | err = lock_mount(path); |
| 1621 | if (err) |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1622 | goto out; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1623 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1624 | old = real_mount(old_path.mnt); |
| 1625 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1626 | err = -EINVAL; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1627 | if (IS_MNT_UNBINDABLE(old)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1628 | goto out2; |
| 1629 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1630 | if (!check_mnt(real_mount(path->mnt)) || !check_mnt(old)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1631 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1632 | |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1633 | if (recurse) |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1634 | mnt = copy_tree(old, old_path.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1635 | else |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1636 | mnt = clone_mnt(old, old_path.dentry, 0); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1637 | |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 1638 | if (IS_ERR(mnt)) { |
| 1639 | err = PTR_ERR(mnt); |
| 1640 | goto out; |
| 1641 | } |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1642 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1643 | err = graft_tree(mnt, path); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1644 | if (err) { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1645 | br_write_lock(&vfsmount_lock); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 1646 | umount_tree(mnt, 0, &umount_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1647 | br_write_unlock(&vfsmount_lock); |
Ram Pai | 5b83d2c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 1648 | } |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1649 | out2: |
| 1650 | unlock_mount(path); |
| 1651 | release_mounts(&umount_list); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 1652 | out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1653 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1654 | return err; |
| 1655 | } |
| 1656 | |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1657 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
| 1658 | { |
| 1659 | int error = 0; |
| 1660 | int readonly_request = 0; |
| 1661 | |
| 1662 | if (ms_flags & MS_RDONLY) |
| 1663 | readonly_request = 1; |
| 1664 | if (readonly_request == __mnt_is_readonly(mnt)) |
| 1665 | return 0; |
| 1666 | |
| 1667 | if (readonly_request) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1668 | error = mnt_make_readonly(real_mount(mnt)); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1669 | else |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1670 | __mnt_unmake_readonly(real_mount(mnt)); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1671 | return error; |
| 1672 | } |
| 1673 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1674 | /* |
| 1675 | * change filesystem flags. dir should be a physical root of filesystem. |
| 1676 | * If you've mounted a non-root directory somewhere and want to do remount |
| 1677 | * on it - tough luck. |
| 1678 | */ |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1679 | static int do_remount(struct path *path, int flags, int mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1680 | void *data) |
| 1681 | { |
| 1682 | int err; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1683 | struct super_block *sb = path->mnt->mnt_sb; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1684 | struct mount *mnt = real_mount(path->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1685 | |
| 1686 | if (!capable(CAP_SYS_ADMIN)) |
| 1687 | return -EPERM; |
| 1688 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1689 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1690 | return -EINVAL; |
| 1691 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1692 | if (path->dentry != path->mnt->mnt_root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1693 | return -EINVAL; |
| 1694 | |
Eric Paris | ff36fe2 | 2011-03-03 16:09:14 -0500 | [diff] [blame] | 1695 | err = security_sb_remount(sb, data); |
| 1696 | if (err) |
| 1697 | return err; |
| 1698 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1699 | down_write(&sb->s_umount); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1700 | if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1701 | err = change_mount_flags(path->mnt, flags); |
Al Viro | 4aa98cf | 2009-05-08 13:36:58 -0400 | [diff] [blame] | 1702 | else |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 1703 | err = do_remount_sb(sb, flags, data, 0); |
Al Viro | 7b43a79 | 2010-01-16 13:01:26 -0500 | [diff] [blame] | 1704 | if (!err) { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1705 | br_write_lock(&vfsmount_lock); |
Eric W. Biederman | 555172d | 2014-07-28 16:26:53 -0700 | [diff] [blame] | 1706 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1707 | mnt->mnt.mnt_flags = mnt_flags; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1708 | br_write_unlock(&vfsmount_lock); |
Al Viro | 7b43a79 | 2010-01-16 13:01:26 -0500 | [diff] [blame] | 1709 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1710 | up_write(&sb->s_umount); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 1711 | if (!err) { |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1712 | br_write_lock(&vfsmount_lock); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1713 | touch_mnt_namespace(mnt->mnt_ns); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1714 | br_write_unlock(&vfsmount_lock); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 1715 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1716 | return err; |
| 1717 | } |
| 1718 | |
Al Viro | cbbe362 | 2011-11-24 20:01:19 -0500 | [diff] [blame] | 1719 | static inline int tree_contains_unbindable(struct mount *mnt) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1720 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1721 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1722 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1723 | if (IS_MNT_UNBINDABLE(p)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1724 | return 1; |
| 1725 | } |
| 1726 | return 0; |
| 1727 | } |
| 1728 | |
Al Viro | 0a0d8a4 | 2008-08-02 00:55:27 -0400 | [diff] [blame] | 1729 | static int do_move_mount(struct path *path, char *old_name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1730 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1731 | struct path old_path, parent_path; |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1732 | struct mount *p; |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1733 | struct mount *old; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1734 | int err = 0; |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1735 | if (!ns_capable(real_mount(path->mnt)->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1736 | return -EPERM; |
| 1737 | if (!old_name || !*old_name) |
| 1738 | return -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1739 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1740 | if (err) |
| 1741 | return err; |
| 1742 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1743 | err = lock_mount(path); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 1744 | if (err < 0) |
| 1745 | goto out; |
| 1746 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1747 | old = real_mount(old_path.mnt); |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1748 | p = real_mount(path->mnt); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1749 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1750 | err = -EINVAL; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1751 | if (!check_mnt(p) || !check_mnt(old)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1752 | goto out1; |
| 1753 | |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 1754 | if (d_unlinked(path->dentry)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1755 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1756 | |
| 1757 | err = -EINVAL; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1758 | if (old_path.dentry != old_path.mnt->mnt_root) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1759 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1760 | |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1761 | if (!mnt_has_parent(old)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1762 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1763 | |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1764 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
| 1765 | S_ISDIR(old_path.dentry->d_inode->i_mode)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1766 | goto out1; |
| 1767 | /* |
| 1768 | * Don't move a mount residing in a shared parent. |
| 1769 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1770 | if (IS_MNT_SHARED(old->mnt_parent)) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1771 | goto out1; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1772 | /* |
| 1773 | * Don't move a mount tree containing unbindable mounts to a destination |
| 1774 | * mount which is shared. |
| 1775 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1776 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1777 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1778 | err = -ELOOP; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 1779 | for (; mnt_has_parent(p); p = p->mnt_parent) |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1780 | if (p == old) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1781 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1782 | |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 1783 | err = attach_recursive_mnt(old, path, &parent_path); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 1784 | if (err) |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 1785 | goto out1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1786 | |
| 1787 | /* if the mount is moved, it should no longer be expire |
| 1788 | * automatically */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1789 | list_del_init(&old->mnt_expire); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1790 | out1: |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1791 | unlock_mount(path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1792 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1793 | if (!err) |
Al Viro | 1a39068 | 2008-03-21 20:48:19 -0400 | [diff] [blame] | 1794 | path_put(&parent_path); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 1795 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1796 | return err; |
| 1797 | } |
| 1798 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1799 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
| 1800 | { |
| 1801 | int err; |
| 1802 | const char *subtype = strchr(fstype, '.'); |
| 1803 | if (subtype) { |
| 1804 | subtype++; |
| 1805 | err = -EINVAL; |
| 1806 | if (!subtype[0]) |
| 1807 | goto err; |
| 1808 | } else |
| 1809 | subtype = ""; |
| 1810 | |
| 1811 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); |
| 1812 | err = -ENOMEM; |
| 1813 | if (!mnt->mnt_sb->s_subtype) |
| 1814 | goto err; |
| 1815 | return mnt; |
| 1816 | |
| 1817 | err: |
| 1818 | mntput(mnt); |
| 1819 | return ERR_PTR(err); |
| 1820 | } |
| 1821 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1822 | /* |
| 1823 | * add a mount into a namespace's mount tree |
| 1824 | */ |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1825 | static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1826 | { |
| 1827 | int err; |
| 1828 | |
| 1829 | mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); |
| 1830 | |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1831 | err = lock_mount(path); |
| 1832 | if (err) |
| 1833 | return err; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1834 | |
| 1835 | err = -EINVAL; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1836 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(real_mount(path->mnt))) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1837 | goto unlock; |
| 1838 | |
| 1839 | /* Refuse the same filesystem on the same mount point */ |
| 1840 | err = -EBUSY; |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1841 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1842 | path->mnt->mnt_root == path->dentry) |
| 1843 | goto unlock; |
| 1844 | |
| 1845 | err = -EINVAL; |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1846 | if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode)) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1847 | goto unlock; |
| 1848 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1849 | newmnt->mnt.mnt_flags = mnt_flags; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1850 | err = graft_tree(newmnt, path); |
| 1851 | |
| 1852 | unlock: |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 1853 | unlock_mount(path); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1854 | return err; |
| 1855 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1856 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1857 | /* |
| 1858 | * create a new mount for userspace and request it to be added into the |
| 1859 | * namespace's tree |
| 1860 | */ |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1861 | static int do_new_mount(struct path *path, const char *fstype, int flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1862 | int mnt_flags, char *name, void *data) |
| 1863 | { |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1864 | struct file_system_type *type; |
| 1865 | struct user_namespace *user_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1866 | struct vfsmount *mnt; |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 1867 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1868 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1869 | if (!fstype) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1870 | return -EINVAL; |
| 1871 | |
| 1872 | /* we need capabilities... */ |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1873 | user_ns = real_mount(path->mnt)->mnt_ns->user_ns; |
| 1874 | if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1875 | return -EPERM; |
| 1876 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 1877 | type = get_fs_type(fstype); |
| 1878 | if (!type) |
| 1879 | return -ENODEV; |
| 1880 | |
| 1881 | if (user_ns != &init_user_ns) { |
| 1882 | if (!(type->fs_flags & FS_USERNS_MOUNT)) { |
| 1883 | put_filesystem(type); |
| 1884 | return -EPERM; |
| 1885 | } |
| 1886 | /* Only in special cases allow devices from mounts |
| 1887 | * created outside the initial user namespace. |
| 1888 | */ |
| 1889 | if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { |
| 1890 | flags |= MS_NODEV; |
| 1891 | mnt_flags |= MNT_NODEV; |
| 1892 | } |
| 1893 | } |
| 1894 | |
| 1895 | mnt = vfs_kern_mount(type, flags, name, data); |
| 1896 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && |
| 1897 | !mnt->mnt_sb->s_subtype) |
| 1898 | mnt = fs_set_subtype(mnt, fstype); |
| 1899 | |
| 1900 | put_filesystem(type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1901 | if (IS_ERR(mnt)) |
| 1902 | return PTR_ERR(mnt); |
| 1903 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1904 | err = do_add_mount(real_mount(mnt), path, mnt_flags); |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 1905 | if (err) |
| 1906 | mntput(mnt); |
| 1907 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1908 | } |
| 1909 | |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1910 | int finish_automount(struct vfsmount *m, struct path *path) |
| 1911 | { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1912 | struct mount *mnt = real_mount(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1913 | int err; |
| 1914 | /* The new mount record should have at least 2 refs to prevent it being |
| 1915 | * expired before we get a chance to add it |
| 1916 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1917 | BUG_ON(mnt_get_count(mnt) < 2); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1918 | |
| 1919 | if (m->mnt_sb == path->mnt->mnt_sb && |
| 1920 | m->mnt_root == path->dentry) { |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1921 | err = -ELOOP; |
| 1922 | goto fail; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1923 | } |
| 1924 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 1925 | err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1926 | if (!err) |
| 1927 | return 0; |
| 1928 | fail: |
| 1929 | /* remove m from any expiration list it may be on */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1930 | if (!list_empty(&mnt->mnt_expire)) { |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1931 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1932 | br_write_lock(&vfsmount_lock); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1933 | list_del_init(&mnt->mnt_expire); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1934 | br_write_unlock(&vfsmount_lock); |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1935 | up_write(&namespace_sem); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1936 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 1937 | mntput(m); |
| 1938 | mntput(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 1939 | return err; |
| 1940 | } |
| 1941 | |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1942 | /** |
| 1943 | * mnt_set_expiry - Put a mount on an expiration list |
| 1944 | * @mnt: The mount to list. |
| 1945 | * @expiry_list: The list to add the mount to. |
| 1946 | */ |
| 1947 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) |
| 1948 | { |
| 1949 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1950 | br_write_lock(&vfsmount_lock); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1951 | |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1952 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1953 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1954 | br_write_unlock(&vfsmount_lock); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 1955 | up_write(&namespace_sem); |
| 1956 | } |
| 1957 | EXPORT_SYMBOL(mnt_set_expiry); |
| 1958 | |
| 1959 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1960 | * process a list of expirable mountpoints with the intent of discarding any |
| 1961 | * mountpoints that aren't in use and haven't been touched since last we came |
| 1962 | * here |
| 1963 | */ |
| 1964 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 1965 | { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 1966 | struct mount *mnt, *next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1967 | LIST_HEAD(graveyard); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1968 | LIST_HEAD(umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1969 | |
| 1970 | if (list_empty(mounts)) |
| 1971 | return; |
| 1972 | |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1973 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1974 | br_write_lock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1975 | |
| 1976 | /* extract from the expiration list every vfsmount that matches the |
| 1977 | * following criteria: |
| 1978 | * - only referenced by its parent vfsmount |
| 1979 | * - still marked for expiry (marked on the last call here; marks are |
| 1980 | * cleared by mntput()) |
| 1981 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1982 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1983 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1984 | propagate_mount_busy(mnt, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1985 | continue; |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1986 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1987 | } |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1988 | while (!list_empty(&graveyard)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1989 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1990 | touch_mnt_namespace(mnt->mnt_ns); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1991 | umount_tree(mnt, 1, &umounts); |
| 1992 | } |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1993 | br_write_unlock(&vfsmount_lock); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 1994 | up_write(&namespace_sem); |
| 1995 | |
| 1996 | release_mounts(&umounts); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1997 | } |
| 1998 | |
| 1999 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 2000 | |
| 2001 | /* |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2002 | * Ripoff of 'select_parent()' |
| 2003 | * |
| 2004 | * search the list of submounts for a given mountpoint, and move any |
| 2005 | * shrinkable submounts to the 'graveyard' list. |
| 2006 | */ |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2007 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2008 | { |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2009 | struct mount *this_parent = parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2010 | struct list_head *next; |
| 2011 | int found = 0; |
| 2012 | |
| 2013 | repeat: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2014 | next = this_parent->mnt_mounts.next; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2015 | resume: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2016 | while (next != &this_parent->mnt_mounts) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2017 | struct list_head *tmp = next; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2018 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2019 | |
| 2020 | next = tmp->next; |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2021 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2022 | continue; |
| 2023 | /* |
| 2024 | * Descend a level if the d_mounts list is non-empty. |
| 2025 | */ |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2026 | if (!list_empty(&mnt->mnt_mounts)) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2027 | this_parent = mnt; |
| 2028 | goto repeat; |
| 2029 | } |
| 2030 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 2031 | if (!propagate_mount_busy(mnt, 1)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2032 | list_move_tail(&mnt->mnt_expire, graveyard); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2033 | found++; |
| 2034 | } |
| 2035 | } |
| 2036 | /* |
| 2037 | * All done at this level ... ascend and resume the search |
| 2038 | */ |
| 2039 | if (this_parent != parent) { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 2040 | next = this_parent->mnt_child.next; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 2041 | this_parent = this_parent->mnt_parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2042 | goto resume; |
| 2043 | } |
| 2044 | return found; |
| 2045 | } |
| 2046 | |
| 2047 | /* |
| 2048 | * process a list of expirable mountpoints with the intent of discarding any |
| 2049 | * submounts of a specific parent mountpoint |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2050 | * |
| 2051 | * vfsmount_lock must be held for write |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2052 | */ |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 2053 | static void shrink_submounts(struct mount *mnt, struct list_head *umounts) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2054 | { |
| 2055 | LIST_HEAD(graveyard); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2056 | struct mount *m; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2057 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2058 | /* extract submounts of 'mountpoint' from the expiration list */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 2059 | while (select_submounts(mnt, &graveyard)) { |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2060 | while (!list_empty(&graveyard)) { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 2061 | m = list_first_entry(&graveyard, struct mount, |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 2062 | mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2063 | touch_mnt_namespace(m->mnt_ns); |
Eric W. Biederman | afef80b | 2008-11-12 13:26:54 -0800 | [diff] [blame] | 2064 | umount_tree(m, 1, umounts); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 2065 | } |
| 2066 | } |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2067 | } |
| 2068 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 2069 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2070 | * Some copy_from_user() implementations do not return the exact number of |
| 2071 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. |
| 2072 | * Note that this function differs from copy_from_user() in that it will oops |
| 2073 | * on bad values of `to', rather than returning a short copy. |
| 2074 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2075 | static long exact_copy_from_user(void *to, const void __user * from, |
| 2076 | unsigned long n) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2077 | { |
| 2078 | char *t = to; |
| 2079 | const char __user *f = from; |
| 2080 | char c; |
| 2081 | |
| 2082 | if (!access_ok(VERIFY_READ, from, n)) |
| 2083 | return n; |
| 2084 | |
| 2085 | while (n) { |
| 2086 | if (__get_user(c, f)) { |
| 2087 | memset(t, 0, n); |
| 2088 | break; |
| 2089 | } |
| 2090 | *t++ = c; |
| 2091 | f++; |
| 2092 | n--; |
| 2093 | } |
| 2094 | return n; |
| 2095 | } |
| 2096 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2097 | int copy_mount_options(const void __user * data, unsigned long *where) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2098 | { |
| 2099 | int i; |
| 2100 | unsigned long page; |
| 2101 | unsigned long size; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2102 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2103 | *where = 0; |
| 2104 | if (!data) |
| 2105 | return 0; |
| 2106 | |
| 2107 | if (!(page = __get_free_page(GFP_KERNEL))) |
| 2108 | return -ENOMEM; |
| 2109 | |
| 2110 | /* We only care that *some* data at the address the user |
| 2111 | * gave us is valid. Just in case, we'll zero |
| 2112 | * the remainder of the page. |
| 2113 | */ |
| 2114 | /* copy_from_user cannot cross TASK_SIZE ! */ |
| 2115 | size = TASK_SIZE - (unsigned long)data; |
| 2116 | if (size > PAGE_SIZE) |
| 2117 | size = PAGE_SIZE; |
| 2118 | |
| 2119 | i = size - exact_copy_from_user((void *)page, data, size); |
| 2120 | if (!i) { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2121 | free_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2122 | return -EFAULT; |
| 2123 | } |
| 2124 | if (i != PAGE_SIZE) |
| 2125 | memset((char *)page + i, 0, PAGE_SIZE - i); |
| 2126 | *where = page; |
| 2127 | return 0; |
| 2128 | } |
| 2129 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2130 | int copy_mount_string(const void __user *data, char **where) |
| 2131 | { |
| 2132 | char *tmp; |
| 2133 | |
| 2134 | if (!data) { |
| 2135 | *where = NULL; |
| 2136 | return 0; |
| 2137 | } |
| 2138 | |
| 2139 | tmp = strndup_user(data, PAGE_SIZE); |
| 2140 | if (IS_ERR(tmp)) |
| 2141 | return PTR_ERR(tmp); |
| 2142 | |
| 2143 | *where = tmp; |
| 2144 | return 0; |
| 2145 | } |
| 2146 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2147 | /* |
| 2148 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 2149 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 2150 | * |
| 2151 | * data is a (void *) that can point to any structure up to |
| 2152 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 2153 | * information (or be NULL). |
| 2154 | * |
| 2155 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 2156 | * When the flags word was introduced its top half was required |
| 2157 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 2158 | * Therefore, if this magic number is present, it carries no information |
| 2159 | * and must be discarded. |
| 2160 | */ |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2161 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2162 | unsigned long flags, void *data_page) |
| 2163 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2164 | struct path path; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2165 | int retval = 0; |
| 2166 | int mnt_flags = 0; |
| 2167 | |
| 2168 | /* Discard magic */ |
| 2169 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 2170 | flags &= ~MS_MGC_MSK; |
| 2171 | |
| 2172 | /* Basic sanity checks */ |
| 2173 | |
| 2174 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) |
| 2175 | return -EINVAL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2176 | |
| 2177 | if (data_page) |
| 2178 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 2179 | |
Tetsuo Handa | a27ab9f | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 2180 | /* ... and get the mountpoint */ |
| 2181 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); |
| 2182 | if (retval) |
| 2183 | return retval; |
| 2184 | |
| 2185 | retval = security_sb_mount(dev_name, &path, |
| 2186 | type_page, flags, data_page); |
| 2187 | if (retval) |
| 2188 | goto dput_out; |
| 2189 | |
Andi Kleen | 613cbe3 | 2009-04-19 18:40:43 +0200 | [diff] [blame] | 2190 | /* Default to relatime unless overriden */ |
| 2191 | if (!(flags & MS_NOATIME)) |
| 2192 | mnt_flags |= MNT_RELATIME; |
Matthew Garrett | 0a1c01c | 2009-03-26 17:53:14 +0000 | [diff] [blame] | 2193 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2194 | /* Separate the per-mountpoint flags */ |
| 2195 | if (flags & MS_NOSUID) |
| 2196 | mnt_flags |= MNT_NOSUID; |
| 2197 | if (flags & MS_NODEV) |
| 2198 | mnt_flags |= MNT_NODEV; |
| 2199 | if (flags & MS_NOEXEC) |
| 2200 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2201 | if (flags & MS_NOATIME) |
| 2202 | mnt_flags |= MNT_NOATIME; |
| 2203 | if (flags & MS_NODIRATIME) |
| 2204 | mnt_flags |= MNT_NODIRATIME; |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2205 | if (flags & MS_STRICTATIME) |
| 2206 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2207 | if (flags & MS_RDONLY) |
| 2208 | mnt_flags |= MNT_READONLY; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 2209 | |
Al Viro | 7a4dec5 | 2010-08-09 12:05:43 -0400 | [diff] [blame] | 2210 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 2211 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
| 2212 | MS_STRICTATIME); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2213 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2214 | if (flags & MS_REMOUNT) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2215 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2216 | data_page); |
| 2217 | else if (flags & MS_BIND) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2218 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2219 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2220 | retval = do_change_type(&path, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2221 | else if (flags & MS_MOVE) |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2222 | retval = do_move_mount(&path, dev_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2223 | else |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2224 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2225 | dev_name, data_page); |
| 2226 | dput_out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2227 | path_put(&path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2228 | return retval; |
| 2229 | } |
| 2230 | |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2231 | |
| 2232 | static void free_mnt_ns(struct mnt_namespace *ns) |
| 2233 | { |
Eric W. Biederman | 80f4b77 | 2015-09-02 16:12:17 +0530 | [diff] [blame] | 2234 | proc_free_inum(ns->proc_inum); |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2235 | put_user_ns(ns->user_ns); |
| 2236 | kfree(ns); |
| 2237 | } |
| 2238 | |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2239 | /* |
| 2240 | * Assign a sequence number so we can detect when we attempt to bind |
| 2241 | * mount a reference to an older mount namespace into the current |
| 2242 | * mount namespace, preventing reference counting loops. A 64bit |
| 2243 | * number incrementing at 10Ghz will take 12,427 years to wrap which |
| 2244 | * is effectively never, so we can ignore the possibility. |
| 2245 | */ |
| 2246 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); |
| 2247 | |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2248 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2249 | { |
| 2250 | struct mnt_namespace *new_ns; |
Eric W. Biederman | 80f4b77 | 2015-09-02 16:12:17 +0530 | [diff] [blame] | 2251 | int ret; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2252 | |
| 2253 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
| 2254 | if (!new_ns) |
| 2255 | return ERR_PTR(-ENOMEM); |
Eric W. Biederman | 80f4b77 | 2015-09-02 16:12:17 +0530 | [diff] [blame] | 2256 | ret = proc_alloc_inum(&new_ns->proc_inum); |
| 2257 | if (ret) { |
| 2258 | kfree(new_ns); |
| 2259 | return ERR_PTR(ret); |
| 2260 | } |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2261 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2262 | atomic_set(&new_ns->count, 1); |
| 2263 | new_ns->root = NULL; |
| 2264 | INIT_LIST_HEAD(&new_ns->list); |
| 2265 | init_waitqueue_head(&new_ns->poll); |
| 2266 | new_ns->event = 0; |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2267 | new_ns->user_ns = get_user_ns(user_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2268 | return new_ns; |
| 2269 | } |
| 2270 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2271 | /* |
| 2272 | * Allocate a new namespace structure and populate it with contents |
| 2273 | * copied from the namespace of the passed in task structure. |
| 2274 | */ |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2275 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2276 | struct user_namespace *user_ns, struct fs_struct *fs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2277 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2278 | struct mnt_namespace *new_ns; |
Al Viro | 7f2da1e | 2008-05-10 20:44:54 -0400 | [diff] [blame] | 2279 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2280 | struct mount *p, *q; |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2281 | struct mount *old = mnt_ns->root; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 2282 | struct mount *new; |
Eric W. Biederman | 4e8a01a | 2015-09-02 15:09:11 +0530 | [diff] [blame] | 2283 | int copy_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2284 | |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2285 | new_ns = alloc_mnt_ns(user_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2286 | if (IS_ERR(new_ns)) |
| 2287 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2288 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2289 | down_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2290 | /* First pass: copy the tree topology */ |
Eric W. Biederman | 4e8a01a | 2015-09-02 15:09:11 +0530 | [diff] [blame] | 2291 | copy_flags = CL_COPY_ALL | CL_EXPIRE; |
| 2292 | if (user_ns != mnt_ns->user_ns) |
| 2293 | copy_flags |= CL_SHARED_TO_SLAVE; |
| 2294 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 2295 | if (IS_ERR(new)) { |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2296 | up_write(&namespace_sem); |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2297 | free_mnt_ns(new_ns); |
David Howells | be4a300 | 2012-06-25 12:55:18 +0100 | [diff] [blame^] | 2298 | return ERR_CAST(new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2299 | } |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2300 | new_ns->root = new; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2301 | br_write_lock(&vfsmount_lock); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2302 | list_add_tail(&new_ns->list, &new->mnt_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2303 | br_write_unlock(&vfsmount_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2304 | |
| 2305 | /* |
| 2306 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 2307 | * as belonging to new namespace. We have already acquired a private |
| 2308 | * fs_struct, so tsk->fs->lock is not needed. |
| 2309 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2310 | p = old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 2311 | q = new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2312 | while (p) { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2313 | q->mnt_ns = new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2314 | if (fs) { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2315 | if (&p->mnt == fs->root.mnt) { |
| 2316 | fs->root.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2317 | rootmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2318 | } |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2319 | if (&p->mnt == fs->pwd.mnt) { |
| 2320 | fs->pwd.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2321 | pwdmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2322 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2323 | } |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2324 | p = next_mnt(p, old); |
| 2325 | q = next_mnt(q, new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2326 | } |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2327 | up_write(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2328 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2329 | if (rootmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 2330 | mntput(rootmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2331 | if (pwdmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 2332 | mntput(pwdmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2333 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2334 | return new_ns; |
| 2335 | } |
| 2336 | |
Eric W. Biederman | 213dd26 | 2007-07-15 23:41:15 -0700 | [diff] [blame] | 2337 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2338 | struct user_namespace *user_ns, struct fs_struct *new_fs) |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2339 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2340 | struct mnt_namespace *new_ns; |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2341 | |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2342 | BUG_ON(!ns); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2343 | get_mnt_ns(ns); |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2344 | |
| 2345 | if (!(flags & CLONE_NEWNS)) |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2346 | return ns; |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2347 | |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2348 | new_ns = dup_mnt_ns(ns, user_ns, new_fs); |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 2349 | |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2350 | put_mnt_ns(ns); |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 2351 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2352 | } |
| 2353 | |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2354 | /** |
| 2355 | * create_mnt_ns - creates a private namespace and adds a root filesystem |
| 2356 | * @mnt: pointer to the new root filesystem mountpoint |
| 2357 | */ |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2358 | static struct mnt_namespace *create_mnt_ns(struct vfsmount *m) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2359 | { |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2360 | struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2361 | if (!IS_ERR(new_ns)) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2362 | struct mount *mnt = real_mount(m); |
| 2363 | mnt->mnt_ns = new_ns; |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2364 | new_ns->root = mnt; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2365 | list_add(&new_ns->list, &mnt->mnt_list); |
Al Viro | c133449 | 2011-11-16 16:12:14 -0500 | [diff] [blame] | 2366 | } else { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2367 | mntput(m); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2368 | } |
| 2369 | return new_ns; |
| 2370 | } |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2371 | |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2372 | struct dentry *mount_subtree(struct vfsmount *mnt, const char *name) |
| 2373 | { |
| 2374 | struct mnt_namespace *ns; |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2375 | struct super_block *s; |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2376 | struct path path; |
| 2377 | int err; |
| 2378 | |
| 2379 | ns = create_mnt_ns(mnt); |
| 2380 | if (IS_ERR(ns)) |
| 2381 | return ERR_CAST(ns); |
| 2382 | |
| 2383 | err = vfs_path_lookup(mnt->mnt_root, mnt, |
| 2384 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
| 2385 | |
| 2386 | put_mnt_ns(ns); |
| 2387 | |
| 2388 | if (err) |
| 2389 | return ERR_PTR(err); |
| 2390 | |
| 2391 | /* trade a vfsmount reference for active sb one */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2392 | s = path.mnt->mnt_sb; |
| 2393 | atomic_inc(&s->s_active); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2394 | mntput(path.mnt); |
| 2395 | /* lock the sucker */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 2396 | down_write(&s->s_umount); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 2397 | /* ... and return the root of (sub)tree on it */ |
| 2398 | return path.dentry; |
| 2399 | } |
| 2400 | EXPORT_SYMBOL(mount_subtree); |
| 2401 | |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 2402 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 2403 | char __user *, type, unsigned long, flags, void __user *, data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2404 | { |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2405 | int ret; |
| 2406 | char *kernel_type; |
| 2407 | char *kernel_dir; |
| 2408 | char *kernel_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2409 | unsigned long data_page; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2410 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2411 | ret = copy_mount_string(type, &kernel_type); |
| 2412 | if (ret < 0) |
| 2413 | goto out_type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2414 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2415 | kernel_dir = getname(dir_name); |
| 2416 | if (IS_ERR(kernel_dir)) { |
| 2417 | ret = PTR_ERR(kernel_dir); |
| 2418 | goto out_dir; |
| 2419 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2420 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2421 | ret = copy_mount_string(dev_name, &kernel_dev); |
| 2422 | if (ret < 0) |
| 2423 | goto out_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2424 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2425 | ret = copy_mount_options(data, &data_page); |
| 2426 | if (ret < 0) |
| 2427 | goto out_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2428 | |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2429 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
| 2430 | (void *) data_page); |
| 2431 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2432 | free_page(data_page); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 2433 | out_data: |
| 2434 | kfree(kernel_dev); |
| 2435 | out_dev: |
| 2436 | putname(kernel_dir); |
| 2437 | out_dir: |
| 2438 | kfree(kernel_type); |
| 2439 | out_type: |
| 2440 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2441 | } |
| 2442 | |
| 2443 | /* |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 2444 | * Return true if path is reachable from root |
| 2445 | * |
| 2446 | * namespace_sem or vfsmount_lock is held |
| 2447 | */ |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 2448 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 2449 | const struct path *root) |
| 2450 | { |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 2451 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 2452 | dentry = mnt->mnt_mountpoint; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 2453 | mnt = mnt->mnt_parent; |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 2454 | } |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 2455 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 2456 | } |
| 2457 | |
| 2458 | int path_is_under(struct path *path1, struct path *path2) |
| 2459 | { |
| 2460 | int res; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2461 | br_read_lock(&vfsmount_lock); |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 2462 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2463 | br_read_unlock(&vfsmount_lock); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 2464 | return res; |
| 2465 | } |
| 2466 | EXPORT_SYMBOL(path_is_under); |
| 2467 | |
| 2468 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2469 | * pivot_root Semantics: |
| 2470 | * Moves the root file system of the current process to the directory put_old, |
| 2471 | * makes new_root as the new root file system of the current process, and sets |
| 2472 | * root/cwd of all processes which had them on the current root to new_root. |
| 2473 | * |
| 2474 | * Restrictions: |
| 2475 | * The new_root and put_old must be directories, and must not be on the |
| 2476 | * same file system as the current process root. The put_old must be |
| 2477 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 2478 | * pointed to by put_old must yield the same directory as new_root. No other |
| 2479 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 2480 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 2481 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
| 2482 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives |
| 2483 | * in this situation. |
| 2484 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2485 | * Notes: |
| 2486 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 2487 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 2488 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 2489 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 2490 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 2491 | * first. |
| 2492 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 2493 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 2494 | const char __user *, put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2495 | { |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2496 | struct path new, old, parent_path, root_parent, root; |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 2497 | struct mount *new_mnt, *root_mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2498 | int error; |
| 2499 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 2500 | if (!ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2501 | return -EPERM; |
| 2502 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2503 | error = user_path_dir(new_root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2504 | if (error) |
| 2505 | goto out0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2506 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2507 | error = user_path_dir(put_old, &old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2508 | if (error) |
| 2509 | goto out1; |
| 2510 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2511 | error = security_sb_pivotroot(&old, &new); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2512 | if (error) |
| 2513 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2514 | |
Miklos Szeredi | f7ad3c6 | 2010-08-10 11:41:36 +0200 | [diff] [blame] | 2515 | get_fs_root(current->fs, &root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2516 | error = lock_mount(&old); |
| 2517 | if (error) |
| 2518 | goto out3; |
| 2519 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2520 | error = -EINVAL; |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 2521 | new_mnt = real_mount(new.mnt); |
| 2522 | root_mnt = real_mount(root.mnt); |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2523 | if (IS_MNT_SHARED(real_mount(old.mnt)) || |
| 2524 | IS_MNT_SHARED(new_mnt->mnt_parent) || |
| 2525 | IS_MNT_SHARED(root_mnt->mnt_parent)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2526 | goto out4; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2527 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2528 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2529 | error = -ENOENT; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 2530 | if (d_unlinked(new.dentry)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2531 | goto out4; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 2532 | if (d_unlinked(old.dentry)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2533 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2534 | error = -EBUSY; |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2535 | if (new.mnt == root.mnt || |
| 2536 | old.mnt == root.mnt) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2537 | goto out4; /* loop, on the same file system */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2538 | error = -EINVAL; |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2539 | if (root.mnt->mnt_root != root.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2540 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2541 | if (!mnt_has_parent(root_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2542 | goto out4; /* not attached */ |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2543 | if (new.mnt->mnt_root != new.dentry) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2544 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 2545 | if (!mnt_has_parent(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2546 | goto out4; /* not attached */ |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2547 | /* make sure we can reach put_old from new_root */ |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 2548 | if (!is_path_reachable(real_mount(old.mnt), old.dentry, &new)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2549 | goto out4; |
Eric W. Biederman | 00ae804 | 2014-10-08 10:42:27 -0700 | [diff] [blame] | 2550 | /* make certain new is below the root */ |
| 2551 | if (!is_path_reachable(new_mnt, new.dentry, &root)) |
| 2552 | goto out4; |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2553 | br_write_lock(&vfsmount_lock); |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 2554 | detach_mnt(new_mnt, &parent_path); |
| 2555 | detach_mnt(root_mnt, &root_parent); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2556 | /* mount old root on put_old */ |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 2557 | attach_mnt(root_mnt, &old); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2558 | /* mount new_root on / */ |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 2559 | attach_mnt(new_mnt, &root_parent); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2560 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2561 | br_write_unlock(&vfsmount_lock); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2562 | chroot_fs_refs(&root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2563 | error = 0; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2564 | out4: |
| 2565 | unlock_mount(&old); |
| 2566 | if (!error) { |
| 2567 | path_put(&root_parent); |
| 2568 | path_put(&parent_path); |
| 2569 | } |
| 2570 | out3: |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 2571 | path_put(&root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2572 | out2: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2573 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2574 | out1: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 2575 | path_put(&new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2576 | out0: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2577 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2578 | } |
| 2579 | |
| 2580 | static void __init init_mount_tree(void) |
| 2581 | { |
| 2582 | struct vfsmount *mnt; |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2583 | struct mnt_namespace *ns; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 2584 | struct path root; |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 2585 | struct file_system_type *type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2586 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 2587 | type = get_fs_type("rootfs"); |
| 2588 | if (!type) |
| 2589 | panic("Can't find rootfs type"); |
| 2590 | mnt = vfs_kern_mount(type, 0, "rootfs", NULL); |
| 2591 | put_filesystem(type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2592 | if (IS_ERR(mnt)) |
| 2593 | panic("Can't create rootfs"); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 2594 | |
Trond Myklebust | 3b22edc | 2009-06-23 17:29:49 -0400 | [diff] [blame] | 2595 | ns = create_mnt_ns(mnt); |
| 2596 | if (IS_ERR(ns)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2597 | panic("Can't allocate initial namespace"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2598 | |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 2599 | init_task.nsproxy->mnt_ns = ns; |
| 2600 | get_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2601 | |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2602 | root.mnt = mnt; |
| 2603 | root.dentry = mnt->mnt_root; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 2604 | |
| 2605 | set_fs_pwd(current->fs, &root); |
| 2606 | set_fs_root(current->fs, &root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2607 | } |
| 2608 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 2609 | void __init mnt_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2610 | { |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 2611 | unsigned u; |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 2612 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2613 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2614 | init_rwsem(&namespace_sem); |
| 2615 | |
Al Viro | 7d6fec4 | 2011-11-23 12:14:10 -0500 | [diff] [blame] | 2616 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 2617 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2618 | |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 2619 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2620 | |
| 2621 | if (!mount_hashtable) |
| 2622 | panic("Failed to allocate mount hash table\n"); |
| 2623 | |
Mandeep Singh Baines | 80cdc6d | 2011-03-22 16:33:54 -0700 | [diff] [blame] | 2624 | printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2625 | |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 2626 | for (u = 0; u < HASH_SIZE; u++) |
| 2627 | INIT_LIST_HEAD(&mount_hashtable[u]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2628 | |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2629 | br_lock_init(&vfsmount_lock); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2630 | |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 2631 | err = sysfs_init(); |
| 2632 | if (err) |
| 2633 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 2634 | __func__, err); |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 2635 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 2636 | if (!fs_kobj) |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 2637 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2638 | init_rootfs(); |
| 2639 | init_mount_tree(); |
| 2640 | } |
| 2641 | |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2642 | void put_mnt_ns(struct mnt_namespace *ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2643 | { |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 2644 | LIST_HEAD(umount_list); |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2645 | |
Al Viro | d498b25 | 2010-02-05 02:21:06 -0500 | [diff] [blame] | 2646 | if (!atomic_dec_and_test(&ns->count)) |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 2647 | return; |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2648 | down_write(&namespace_sem); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2649 | br_write_lock(&vfsmount_lock); |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 2650 | umount_tree(ns->root, 0, &umount_list); |
Andi Kleen | f076950 | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 2651 | br_write_unlock(&vfsmount_lock); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 2652 | up_write(&namespace_sem); |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 2653 | release_mounts(&umount_list); |
Eric W. Biederman | 9bfaf4f | 2015-09-02 14:51:14 +0530 | [diff] [blame] | 2654 | free_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2655 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2656 | |
| 2657 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) |
| 2658 | { |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 2659 | struct vfsmount *mnt; |
| 2660 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); |
| 2661 | if (!IS_ERR(mnt)) { |
| 2662 | /* |
| 2663 | * it is a longterm mount, don't release mnt until |
| 2664 | * we unmount before file sys is unregistered |
| 2665 | */ |
Al Viro | d9eb504 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 2666 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 2667 | } |
| 2668 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 2669 | } |
| 2670 | EXPORT_SYMBOL_GPL(kern_mount_data); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 2671 | |
| 2672 | void kern_unmount(struct vfsmount *mnt) |
| 2673 | { |
| 2674 | /* release long term mount so mount point can be released */ |
| 2675 | if (!IS_ERR_OR_NULL(mnt)) { |
Al Viro | d9eb504 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 2676 | br_write_lock(&vfsmount_lock); |
| 2677 | real_mount(mnt)->mnt_ns = NULL; |
| 2678 | br_write_unlock(&vfsmount_lock); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 2679 | mntput(mnt); |
| 2680 | } |
| 2681 | } |
| 2682 | EXPORT_SYMBOL(kern_unmount); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2683 | |
| 2684 | bool our_mnt(struct vfsmount *mnt) |
| 2685 | { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2686 | return check_mnt(real_mount(mnt)); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 2687 | } |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2688 | |
| 2689 | static void *mntns_get(struct task_struct *task) |
| 2690 | { |
| 2691 | struct mnt_namespace *ns = NULL; |
| 2692 | struct nsproxy *nsproxy; |
| 2693 | |
| 2694 | rcu_read_lock(); |
| 2695 | nsproxy = task_nsproxy(task); |
| 2696 | if (nsproxy) { |
| 2697 | ns = nsproxy->mnt_ns; |
| 2698 | get_mnt_ns(ns); |
| 2699 | } |
| 2700 | rcu_read_unlock(); |
| 2701 | |
| 2702 | return ns; |
| 2703 | } |
| 2704 | |
| 2705 | static void mntns_put(void *ns) |
| 2706 | { |
| 2707 | put_mnt_ns(ns); |
| 2708 | } |
| 2709 | |
| 2710 | static int mntns_install(struct nsproxy *nsproxy, void *ns) |
| 2711 | { |
| 2712 | struct fs_struct *fs = current->fs; |
| 2713 | struct mnt_namespace *mnt_ns = ns; |
| 2714 | struct path root; |
| 2715 | |
Eric W. Biederman | 80efab3 | 2015-09-02 15:57:46 +0530 | [diff] [blame] | 2716 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
| 2717 | !nsown_capable(CAP_SYS_CHROOT)) |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2718 | return -EINVAL; |
| 2719 | |
| 2720 | if (fs->users != 1) |
| 2721 | return -EINVAL; |
| 2722 | |
| 2723 | get_mnt_ns(mnt_ns); |
| 2724 | put_mnt_ns(nsproxy->mnt_ns); |
| 2725 | nsproxy->mnt_ns = mnt_ns; |
| 2726 | |
| 2727 | /* Find the root */ |
| 2728 | root.mnt = &mnt_ns->root->mnt; |
| 2729 | root.dentry = mnt_ns->root->mnt.mnt_root; |
| 2730 | path_get(&root); |
| 2731 | while(d_mountpoint(root.dentry) && follow_down_one(&root)) |
| 2732 | ; |
| 2733 | |
| 2734 | /* Update the pwd and root */ |
| 2735 | set_fs_pwd(fs, &root); |
| 2736 | set_fs_root(fs, &root); |
| 2737 | |
| 2738 | path_put(&root); |
| 2739 | return 0; |
| 2740 | } |
| 2741 | |
Eric W. Biederman | 80f4b77 | 2015-09-02 16:12:17 +0530 | [diff] [blame] | 2742 | static unsigned int mntns_inum(void *ns) |
| 2743 | { |
| 2744 | struct mnt_namespace *mnt_ns = ns; |
| 2745 | return mnt_ns->proc_inum; |
| 2746 | } |
| 2747 | |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2748 | const struct proc_ns_operations mntns_operations = { |
| 2749 | .name = "mnt", |
| 2750 | .type = CLONE_NEWNS, |
| 2751 | .get = mntns_get, |
| 2752 | .put = mntns_put, |
| 2753 | .install = mntns_install, |
Eric W. Biederman | 80f4b77 | 2015-09-02 16:12:17 +0530 | [diff] [blame] | 2754 | .inum = mntns_inum, |
Eric W. Biederman | 474fc3e | 2015-09-02 13:42:53 +0530 | [diff] [blame] | 2755 | }; |