Commit | Line | Data |
---|---|---|
1da177e4 LT |
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 | ||
1da177e4 | 11 | #include <linux/syscalls.h> |
d10577a8 | 12 | #include <linux/export.h> |
16f7e0fe | 13 | #include <linux/capability.h> |
6b3286ed | 14 | #include <linux/mnt_namespace.h> |
771b1371 | 15 | #include <linux/user_namespace.h> |
1da177e4 LT |
16 | #include <linux/namei.h> |
17 | #include <linux/security.h> | |
73cd49ec | 18 | #include <linux/idr.h> |
57f150a5 | 19 | #include <linux/init.h> /* init_rootfs */ |
d10577a8 AV |
20 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
21 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ | |
22 | #include <linux/uaccess.h> | |
0bb80f24 | 23 | #include <linux/proc_ns.h> |
20b4fb48 | 24 | #include <linux/magic.h> |
0818bf27 | 25 | #include <linux/bootmem.h> |
9ea459e1 | 26 | #include <linux/task_work.h> |
07b20889 | 27 | #include "pnode.h" |
948730b0 | 28 | #include "internal.h" |
1da177e4 | 29 | |
0818bf27 AV |
30 | static unsigned int m_hash_mask __read_mostly; |
31 | static unsigned int m_hash_shift __read_mostly; | |
32 | static unsigned int mp_hash_mask __read_mostly; | |
33 | static unsigned int mp_hash_shift __read_mostly; | |
34 | ||
35 | static __initdata unsigned long mhash_entries; | |
36 | static int __init set_mhash_entries(char *str) | |
37 | { | |
38 | if (!str) | |
39 | return 0; | |
40 | mhash_entries = simple_strtoul(str, &str, 0); | |
41 | return 1; | |
42 | } | |
43 | __setup("mhash_entries=", set_mhash_entries); | |
44 | ||
45 | static __initdata unsigned long mphash_entries; | |
46 | static int __init set_mphash_entries(char *str) | |
47 | { | |
48 | if (!str) | |
49 | return 0; | |
50 | mphash_entries = simple_strtoul(str, &str, 0); | |
51 | return 1; | |
52 | } | |
53 | __setup("mphash_entries=", set_mphash_entries); | |
13f14b4d | 54 | |
c7999c36 | 55 | static u64 event; |
73cd49ec | 56 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 57 | static DEFINE_IDA(mnt_group_ida); |
99b7db7b | 58 | static DEFINE_SPINLOCK(mnt_id_lock); |
f21f6220 AV |
59 | static int mnt_id_start = 0; |
60 | static int mnt_group_start = 1; | |
1da177e4 | 61 | |
38129a13 | 62 | static struct hlist_head *mount_hashtable __read_mostly; |
0818bf27 | 63 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
e18b890b | 64 | static struct kmem_cache *mnt_cache __read_mostly; |
59aa0da8 | 65 | static DECLARE_RWSEM(namespace_sem); |
1da177e4 | 66 | |
f87fd4c2 | 67 | /* /sys/fs */ |
00d26666 GKH |
68 | struct kobject *fs_kobj; |
69 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 70 | |
99b7db7b NP |
71 | /* |
72 | * vfsmount lock may be taken for read to prevent changes to the | |
73 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
74 | * up the tree. | |
75 | * | |
76 | * It should be taken for write in all cases where the vfsmount | |
77 | * tree or hash is modified or when a vfsmount structure is modified. | |
78 | */ | |
48a066e7 | 79 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
99b7db7b | 80 | |
38129a13 | 81 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 82 | { |
b58fed8b RP |
83 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
84 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
0818bf27 AV |
85 | tmp = tmp + (tmp >> m_hash_shift); |
86 | return &mount_hashtable[tmp & m_hash_mask]; | |
87 | } | |
88 | ||
89 | static inline struct hlist_head *mp_hash(struct dentry *dentry) | |
90 | { | |
91 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); | |
92 | tmp = tmp + (tmp >> mp_hash_shift); | |
93 | return &mountpoint_hashtable[tmp & mp_hash_mask]; | |
1da177e4 LT |
94 | } |
95 | ||
99b7db7b NP |
96 | /* |
97 | * allocation is serialized by namespace_sem, but we need the spinlock to | |
98 | * serialize with freeing. | |
99 | */ | |
b105e270 | 100 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec MS |
101 | { |
102 | int res; | |
103 | ||
104 | retry: | |
105 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); | |
99b7db7b | 106 | spin_lock(&mnt_id_lock); |
15169fe7 | 107 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
f21f6220 | 108 | if (!res) |
15169fe7 | 109 | mnt_id_start = mnt->mnt_id + 1; |
99b7db7b | 110 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
111 | if (res == -EAGAIN) |
112 | goto retry; | |
113 | ||
114 | return res; | |
115 | } | |
116 | ||
b105e270 | 117 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 118 | { |
15169fe7 | 119 | int id = mnt->mnt_id; |
99b7db7b | 120 | spin_lock(&mnt_id_lock); |
f21f6220 AV |
121 | ida_remove(&mnt_id_ida, id); |
122 | if (mnt_id_start > id) | |
123 | mnt_id_start = id; | |
99b7db7b | 124 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
125 | } |
126 | ||
719f5d7f MS |
127 | /* |
128 | * Allocate a new peer group ID | |
129 | * | |
130 | * mnt_group_ida is protected by namespace_sem | |
131 | */ | |
4b8b21f4 | 132 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 133 | { |
f21f6220 AV |
134 | int res; |
135 | ||
719f5d7f MS |
136 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
137 | return -ENOMEM; | |
138 | ||
f21f6220 AV |
139 | res = ida_get_new_above(&mnt_group_ida, |
140 | mnt_group_start, | |
15169fe7 | 141 | &mnt->mnt_group_id); |
f21f6220 | 142 | if (!res) |
15169fe7 | 143 | mnt_group_start = mnt->mnt_group_id + 1; |
f21f6220 AV |
144 | |
145 | return res; | |
719f5d7f MS |
146 | } |
147 | ||
148 | /* | |
149 | * Release a peer group ID | |
150 | */ | |
4b8b21f4 | 151 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 152 | { |
15169fe7 | 153 | int id = mnt->mnt_group_id; |
f21f6220 AV |
154 | ida_remove(&mnt_group_ida, id); |
155 | if (mnt_group_start > id) | |
156 | mnt_group_start = id; | |
15169fe7 | 157 | mnt->mnt_group_id = 0; |
719f5d7f MS |
158 | } |
159 | ||
b3e19d92 NP |
160 | /* |
161 | * vfsmount lock must be held for read | |
162 | */ | |
83adc753 | 163 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
164 | { |
165 | #ifdef CONFIG_SMP | |
68e8a9fe | 166 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
167 | #else |
168 | preempt_disable(); | |
68e8a9fe | 169 | mnt->mnt_count += n; |
b3e19d92 NP |
170 | preempt_enable(); |
171 | #endif | |
172 | } | |
173 | ||
b3e19d92 NP |
174 | /* |
175 | * vfsmount lock must be held for write | |
176 | */ | |
83adc753 | 177 | unsigned int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
178 | { |
179 | #ifdef CONFIG_SMP | |
f03c6599 | 180 | unsigned int count = 0; |
b3e19d92 NP |
181 | int cpu; |
182 | ||
183 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 184 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
185 | } |
186 | ||
187 | return count; | |
188 | #else | |
68e8a9fe | 189 | return mnt->mnt_count; |
b3e19d92 NP |
190 | #endif |
191 | } | |
192 | ||
87b95ce0 AV |
193 | static void drop_mountpoint(struct fs_pin *p) |
194 | { | |
195 | struct mount *m = container_of(p, struct mount, mnt_umount); | |
196 | dput(m->mnt_ex_mountpoint); | |
197 | pin_remove(p); | |
198 | mntput(&m->mnt); | |
199 | } | |
200 | ||
b105e270 | 201 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 202 | { |
c63181e6 AV |
203 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
204 | if (mnt) { | |
73cd49ec MS |
205 | int err; |
206 | ||
c63181e6 | 207 | err = mnt_alloc_id(mnt); |
88b38782 LZ |
208 | if (err) |
209 | goto out_free_cache; | |
210 | ||
211 | if (name) { | |
fcc139ae | 212 | mnt->mnt_devname = kstrdup_const(name, GFP_KERNEL); |
c63181e6 | 213 | if (!mnt->mnt_devname) |
88b38782 | 214 | goto out_free_id; |
73cd49ec MS |
215 | } |
216 | ||
b3e19d92 | 217 | #ifdef CONFIG_SMP |
c63181e6 AV |
218 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
219 | if (!mnt->mnt_pcp) | |
b3e19d92 NP |
220 | goto out_free_devname; |
221 | ||
c63181e6 | 222 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
b3e19d92 | 223 | #else |
c63181e6 AV |
224 | mnt->mnt_count = 1; |
225 | mnt->mnt_writers = 0; | |
b3e19d92 NP |
226 | #endif |
227 | ||
38129a13 | 228 | INIT_HLIST_NODE(&mnt->mnt_hash); |
c63181e6 AV |
229 | INIT_LIST_HEAD(&mnt->mnt_child); |
230 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
231 | INIT_LIST_HEAD(&mnt->mnt_list); | |
232 | INIT_LIST_HEAD(&mnt->mnt_expire); | |
233 | INIT_LIST_HEAD(&mnt->mnt_share); | |
234 | INIT_LIST_HEAD(&mnt->mnt_slave_list); | |
235 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
0a5eb7c8 | 236 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
2504c5d6 AG |
237 | #ifdef CONFIG_FSNOTIFY |
238 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); | |
d3ef3d73 | 239 | #endif |
87b95ce0 | 240 | init_fs_pin(&mnt->mnt_umount, drop_mountpoint); |
1da177e4 | 241 | } |
c63181e6 | 242 | return mnt; |
88b38782 | 243 | |
d3ef3d73 | 244 | #ifdef CONFIG_SMP |
245 | out_free_devname: | |
fcc139ae | 246 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 247 | #endif |
88b38782 | 248 | out_free_id: |
c63181e6 | 249 | mnt_free_id(mnt); |
88b38782 | 250 | out_free_cache: |
c63181e6 | 251 | kmem_cache_free(mnt_cache, mnt); |
88b38782 | 252 | return NULL; |
1da177e4 LT |
253 | } |
254 | ||
3d733633 DH |
255 | /* |
256 | * Most r/o checks on a fs are for operations that take | |
257 | * discrete amounts of time, like a write() or unlink(). | |
258 | * We must keep track of when those operations start | |
259 | * (for permission checks) and when they end, so that | |
260 | * we can determine when writes are able to occur to | |
261 | * a filesystem. | |
262 | */ | |
263 | /* | |
264 | * __mnt_is_readonly: check whether a mount is read-only | |
265 | * @mnt: the mount to check for its write status | |
266 | * | |
267 | * This shouldn't be used directly ouside of the VFS. | |
268 | * It does not guarantee that the filesystem will stay | |
269 | * r/w, just that it is right *now*. This can not and | |
270 | * should not be used in place of IS_RDONLY(inode). | |
271 | * mnt_want/drop_write() will _keep_ the filesystem | |
272 | * r/w. | |
273 | */ | |
274 | int __mnt_is_readonly(struct vfsmount *mnt) | |
275 | { | |
2e4b7fcd DH |
276 | if (mnt->mnt_flags & MNT_READONLY) |
277 | return 1; | |
278 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
279 | return 1; | |
280 | return 0; | |
3d733633 DH |
281 | } |
282 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
283 | ||
83adc753 | 284 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 | 285 | { |
286 | #ifdef CONFIG_SMP | |
68e8a9fe | 287 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 288 | #else |
68e8a9fe | 289 | mnt->mnt_writers++; |
d3ef3d73 | 290 | #endif |
291 | } | |
3d733633 | 292 | |
83adc753 | 293 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 294 | { |
d3ef3d73 | 295 | #ifdef CONFIG_SMP |
68e8a9fe | 296 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 297 | #else |
68e8a9fe | 298 | mnt->mnt_writers--; |
d3ef3d73 | 299 | #endif |
3d733633 | 300 | } |
3d733633 | 301 | |
83adc753 | 302 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 303 | { |
d3ef3d73 | 304 | #ifdef CONFIG_SMP |
305 | unsigned int count = 0; | |
3d733633 | 306 | int cpu; |
3d733633 DH |
307 | |
308 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 309 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 310 | } |
3d733633 | 311 | |
d3ef3d73 | 312 | return count; |
313 | #else | |
314 | return mnt->mnt_writers; | |
315 | #endif | |
3d733633 DH |
316 | } |
317 | ||
4ed5e82f MS |
318 | static int mnt_is_readonly(struct vfsmount *mnt) |
319 | { | |
320 | if (mnt->mnt_sb->s_readonly_remount) | |
321 | return 1; | |
322 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ | |
323 | smp_rmb(); | |
324 | return __mnt_is_readonly(mnt); | |
325 | } | |
326 | ||
8366025e | 327 | /* |
eb04c282 JK |
328 | * Most r/o & frozen checks on a fs are for operations that take discrete |
329 | * amounts of time, like a write() or unlink(). We must keep track of when | |
330 | * those operations start (for permission checks) and when they end, so that we | |
331 | * can determine when writes are able to occur to a filesystem. | |
8366025e DH |
332 | */ |
333 | /** | |
eb04c282 | 334 | * __mnt_want_write - get write access to a mount without freeze protection |
83adc753 | 335 | * @m: the mount on which to take a write |
8366025e | 336 | * |
eb04c282 JK |
337 | * This tells the low-level filesystem that a write is about to be performed to |
338 | * it, and makes sure that writes are allowed (mnt it read-write) before | |
339 | * returning success. This operation does not protect against filesystem being | |
340 | * frozen. When the write operation is finished, __mnt_drop_write() must be | |
341 | * called. This is effectively a refcount. | |
8366025e | 342 | */ |
eb04c282 | 343 | int __mnt_want_write(struct vfsmount *m) |
8366025e | 344 | { |
83adc753 | 345 | struct mount *mnt = real_mount(m); |
3d733633 | 346 | int ret = 0; |
3d733633 | 347 | |
d3ef3d73 | 348 | preempt_disable(); |
c6653a83 | 349 | mnt_inc_writers(mnt); |
d3ef3d73 | 350 | /* |
c6653a83 | 351 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 | 352 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
353 | * incremented count after it has set MNT_WRITE_HOLD. | |
354 | */ | |
355 | smp_mb(); | |
1e75529e | 356 | while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) |
d3ef3d73 | 357 | cpu_relax(); |
358 | /* | |
359 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
360 | * be set to match its requirements. So we must not load that until | |
361 | * MNT_WRITE_HOLD is cleared. | |
362 | */ | |
363 | smp_rmb(); | |
4ed5e82f | 364 | if (mnt_is_readonly(m)) { |
c6653a83 | 365 | mnt_dec_writers(mnt); |
3d733633 | 366 | ret = -EROFS; |
3d733633 | 367 | } |
d3ef3d73 | 368 | preempt_enable(); |
eb04c282 JK |
369 | |
370 | return ret; | |
371 | } | |
372 | ||
373 | /** | |
374 | * mnt_want_write - get write access to a mount | |
375 | * @m: the mount on which to take a write | |
376 | * | |
377 | * This tells the low-level filesystem that a write is about to be performed to | |
378 | * it, and makes sure that writes are allowed (mount is read-write, filesystem | |
379 | * is not frozen) before returning success. When the write operation is | |
380 | * finished, mnt_drop_write() must be called. This is effectively a refcount. | |
381 | */ | |
382 | int mnt_want_write(struct vfsmount *m) | |
383 | { | |
384 | int ret; | |
385 | ||
386 | sb_start_write(m->mnt_sb); | |
387 | ret = __mnt_want_write(m); | |
388 | if (ret) | |
389 | sb_end_write(m->mnt_sb); | |
3d733633 | 390 | return ret; |
8366025e DH |
391 | } |
392 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
393 | ||
96029c4e | 394 | /** |
395 | * mnt_clone_write - get write access to a mount | |
396 | * @mnt: the mount on which to take a write | |
397 | * | |
398 | * This is effectively like mnt_want_write, except | |
399 | * it must only be used to take an extra write reference | |
400 | * on a mountpoint that we already know has a write reference | |
401 | * on it. This allows some optimisation. | |
402 | * | |
403 | * After finished, mnt_drop_write must be called as usual to | |
404 | * drop the reference. | |
405 | */ | |
406 | int mnt_clone_write(struct vfsmount *mnt) | |
407 | { | |
408 | /* superblock may be r/o */ | |
409 | if (__mnt_is_readonly(mnt)) | |
410 | return -EROFS; | |
411 | preempt_disable(); | |
83adc753 | 412 | mnt_inc_writers(real_mount(mnt)); |
96029c4e | 413 | preempt_enable(); |
414 | return 0; | |
415 | } | |
416 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
417 | ||
418 | /** | |
eb04c282 | 419 | * __mnt_want_write_file - get write access to a file's mount |
96029c4e | 420 | * @file: the file who's mount on which to take a write |
421 | * | |
eb04c282 | 422 | * This is like __mnt_want_write, but it takes a file and can |
96029c4e | 423 | * do some optimisations if the file is open for write already |
424 | */ | |
eb04c282 | 425 | int __mnt_want_write_file(struct file *file) |
96029c4e | 426 | { |
83f936c7 | 427 | if (!(file->f_mode & FMODE_WRITER)) |
eb04c282 | 428 | return __mnt_want_write(file->f_path.mnt); |
96029c4e | 429 | else |
430 | return mnt_clone_write(file->f_path.mnt); | |
431 | } | |
eb04c282 JK |
432 | |
433 | /** | |
434 | * mnt_want_write_file - get write access to a file's mount | |
435 | * @file: the file who's mount on which to take a write | |
436 | * | |
437 | * This is like mnt_want_write, but it takes a file and can | |
438 | * do some optimisations if the file is open for write already | |
439 | */ | |
440 | int mnt_want_write_file(struct file *file) | |
441 | { | |
442 | int ret; | |
443 | ||
444 | sb_start_write(file->f_path.mnt->mnt_sb); | |
445 | ret = __mnt_want_write_file(file); | |
446 | if (ret) | |
447 | sb_end_write(file->f_path.mnt->mnt_sb); | |
448 | return ret; | |
449 | } | |
96029c4e | 450 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
451 | ||
8366025e | 452 | /** |
eb04c282 | 453 | * __mnt_drop_write - give up write access to a mount |
8366025e DH |
454 | * @mnt: the mount on which to give up write access |
455 | * | |
456 | * Tells the low-level filesystem that we are done | |
457 | * performing writes to it. Must be matched with | |
eb04c282 | 458 | * __mnt_want_write() call above. |
8366025e | 459 | */ |
eb04c282 | 460 | void __mnt_drop_write(struct vfsmount *mnt) |
8366025e | 461 | { |
d3ef3d73 | 462 | preempt_disable(); |
83adc753 | 463 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 464 | preempt_enable(); |
8366025e | 465 | } |
eb04c282 JK |
466 | |
467 | /** | |
468 | * mnt_drop_write - give up write access to a mount | |
469 | * @mnt: the mount on which to give up write access | |
470 | * | |
471 | * Tells the low-level filesystem that we are done performing writes to it and | |
472 | * also allows filesystem to be frozen again. Must be matched with | |
473 | * mnt_want_write() call above. | |
474 | */ | |
475 | void mnt_drop_write(struct vfsmount *mnt) | |
476 | { | |
477 | __mnt_drop_write(mnt); | |
478 | sb_end_write(mnt->mnt_sb); | |
479 | } | |
8366025e DH |
480 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
481 | ||
eb04c282 JK |
482 | void __mnt_drop_write_file(struct file *file) |
483 | { | |
484 | __mnt_drop_write(file->f_path.mnt); | |
485 | } | |
486 | ||
2a79f17e AV |
487 | void mnt_drop_write_file(struct file *file) |
488 | { | |
489 | mnt_drop_write(file->f_path.mnt); | |
490 | } | |
491 | EXPORT_SYMBOL(mnt_drop_write_file); | |
492 | ||
83adc753 | 493 | static int mnt_make_readonly(struct mount *mnt) |
8366025e | 494 | { |
3d733633 DH |
495 | int ret = 0; |
496 | ||
719ea2fb | 497 | lock_mount_hash(); |
83adc753 | 498 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 499 | /* |
d3ef3d73 | 500 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
501 | * should be visible before we do. | |
3d733633 | 502 | */ |
d3ef3d73 | 503 | smp_mb(); |
504 | ||
3d733633 | 505 | /* |
d3ef3d73 | 506 | * With writers on hold, if this value is zero, then there are |
507 | * definitely no active writers (although held writers may subsequently | |
508 | * increment the count, they'll have to wait, and decrement it after | |
509 | * seeing MNT_READONLY). | |
510 | * | |
511 | * It is OK to have counter incremented on one CPU and decremented on | |
512 | * another: the sum will add up correctly. The danger would be when we | |
513 | * sum up each counter, if we read a counter before it is incremented, | |
514 | * but then read another CPU's count which it has been subsequently | |
515 | * decremented from -- we would see more decrements than we should. | |
516 | * MNT_WRITE_HOLD protects against this scenario, because | |
517 | * mnt_want_write first increments count, then smp_mb, then spins on | |
518 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
519 | * we're counting up here. | |
3d733633 | 520 | */ |
c6653a83 | 521 | if (mnt_get_writers(mnt) > 0) |
d3ef3d73 | 522 | ret = -EBUSY; |
523 | else | |
83adc753 | 524 | mnt->mnt.mnt_flags |= MNT_READONLY; |
d3ef3d73 | 525 | /* |
526 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
527 | * that become unheld will see MNT_READONLY. | |
528 | */ | |
529 | smp_wmb(); | |
83adc753 | 530 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
719ea2fb | 531 | unlock_mount_hash(); |
3d733633 | 532 | return ret; |
8366025e | 533 | } |
8366025e | 534 | |
83adc753 | 535 | static void __mnt_unmake_readonly(struct mount *mnt) |
2e4b7fcd | 536 | { |
719ea2fb | 537 | lock_mount_hash(); |
83adc753 | 538 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
719ea2fb | 539 | unlock_mount_hash(); |
2e4b7fcd DH |
540 | } |
541 | ||
4ed5e82f MS |
542 | int sb_prepare_remount_readonly(struct super_block *sb) |
543 | { | |
544 | struct mount *mnt; | |
545 | int err = 0; | |
546 | ||
8e8b8796 MS |
547 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
548 | if (atomic_long_read(&sb->s_remove_count)) | |
549 | return -EBUSY; | |
550 | ||
719ea2fb | 551 | lock_mount_hash(); |
4ed5e82f MS |
552 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
553 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { | |
554 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; | |
555 | smp_mb(); | |
556 | if (mnt_get_writers(mnt) > 0) { | |
557 | err = -EBUSY; | |
558 | break; | |
559 | } | |
560 | } | |
561 | } | |
8e8b8796 MS |
562 | if (!err && atomic_long_read(&sb->s_remove_count)) |
563 | err = -EBUSY; | |
564 | ||
4ed5e82f MS |
565 | if (!err) { |
566 | sb->s_readonly_remount = 1; | |
567 | smp_wmb(); | |
568 | } | |
569 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { | |
570 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) | |
571 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; | |
572 | } | |
719ea2fb | 573 | unlock_mount_hash(); |
4ed5e82f MS |
574 | |
575 | return err; | |
576 | } | |
577 | ||
b105e270 | 578 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 579 | { |
fcc139ae | 580 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 581 | #ifdef CONFIG_SMP |
68e8a9fe | 582 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 583 | #endif |
b105e270 | 584 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
585 | } |
586 | ||
8ffcb32e DH |
587 | static void delayed_free_vfsmnt(struct rcu_head *head) |
588 | { | |
589 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); | |
590 | } | |
591 | ||
48a066e7 | 592 | /* call under rcu_read_lock */ |
294d71ff | 593 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
48a066e7 AV |
594 | { |
595 | struct mount *mnt; | |
596 | if (read_seqretry(&mount_lock, seq)) | |
294d71ff | 597 | return 1; |
48a066e7 | 598 | if (bastard == NULL) |
294d71ff | 599 | return 0; |
48a066e7 AV |
600 | mnt = real_mount(bastard); |
601 | mnt_add_count(mnt, 1); | |
602 | if (likely(!read_seqretry(&mount_lock, seq))) | |
294d71ff | 603 | return 0; |
48a066e7 AV |
604 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
605 | mnt_add_count(mnt, -1); | |
294d71ff AV |
606 | return 1; |
607 | } | |
608 | return -1; | |
609 | } | |
610 | ||
611 | /* call under rcu_read_lock */ | |
612 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) | |
613 | { | |
614 | int res = __legitimize_mnt(bastard, seq); | |
615 | if (likely(!res)) | |
616 | return true; | |
617 | if (unlikely(res < 0)) { | |
618 | rcu_read_unlock(); | |
619 | mntput(bastard); | |
620 | rcu_read_lock(); | |
48a066e7 | 621 | } |
48a066e7 AV |
622 | return false; |
623 | } | |
624 | ||
1da177e4 | 625 | /* |
474279dc | 626 | * find the first mount at @dentry on vfsmount @mnt. |
48a066e7 | 627 | * call under rcu_read_lock() |
1da177e4 | 628 | */ |
474279dc | 629 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 630 | { |
38129a13 | 631 | struct hlist_head *head = m_hash(mnt, dentry); |
474279dc AV |
632 | struct mount *p; |
633 | ||
38129a13 | 634 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
474279dc AV |
635 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
636 | return p; | |
637 | return NULL; | |
638 | } | |
639 | ||
640 | /* | |
641 | * find the last mount at @dentry on vfsmount @mnt. | |
48a066e7 | 642 | * mount_lock must be held. |
474279dc AV |
643 | */ |
644 | struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry) | |
645 | { | |
411a938b EB |
646 | struct mount *p, *res = NULL; |
647 | p = __lookup_mnt(mnt, dentry); | |
38129a13 AV |
648 | if (!p) |
649 | goto out; | |
411a938b EB |
650 | if (!(p->mnt.mnt_flags & MNT_UMOUNT)) |
651 | res = p; | |
38129a13 | 652 | hlist_for_each_entry_continue(p, mnt_hash) { |
1d6a32ac AV |
653 | if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry) |
654 | break; | |
411a938b EB |
655 | if (!(p->mnt.mnt_flags & MNT_UMOUNT)) |
656 | res = p; | |
1d6a32ac | 657 | } |
38129a13 | 658 | out: |
1d6a32ac | 659 | return res; |
1da177e4 LT |
660 | } |
661 | ||
a05964f3 | 662 | /* |
f015f126 DH |
663 | * lookup_mnt - Return the first child mount mounted at path |
664 | * | |
665 | * "First" means first mounted chronologically. If you create the | |
666 | * following mounts: | |
667 | * | |
668 | * mount /dev/sda1 /mnt | |
669 | * mount /dev/sda2 /mnt | |
670 | * mount /dev/sda3 /mnt | |
671 | * | |
672 | * Then lookup_mnt() on the base /mnt dentry in the root mount will | |
673 | * return successively the root dentry and vfsmount of /dev/sda1, then | |
674 | * /dev/sda2, then /dev/sda3, then NULL. | |
675 | * | |
676 | * lookup_mnt takes a reference to the found vfsmount. | |
a05964f3 | 677 | */ |
1c755af4 | 678 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 | 679 | { |
c7105365 | 680 | struct mount *child_mnt; |
48a066e7 AV |
681 | struct vfsmount *m; |
682 | unsigned seq; | |
99b7db7b | 683 | |
48a066e7 AV |
684 | rcu_read_lock(); |
685 | do { | |
686 | seq = read_seqbegin(&mount_lock); | |
687 | child_mnt = __lookup_mnt(path->mnt, path->dentry); | |
688 | m = child_mnt ? &child_mnt->mnt : NULL; | |
689 | } while (!legitimize_mnt(m, seq)); | |
690 | rcu_read_unlock(); | |
691 | return m; | |
a05964f3 RP |
692 | } |
693 | ||
7af1364f EB |
694 | /* |
695 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the | |
696 | * current mount namespace. | |
697 | * | |
698 | * The common case is dentries are not mountpoints at all and that | |
699 | * test is handled inline. For the slow case when we are actually | |
700 | * dealing with a mountpoint of some kind, walk through all of the | |
701 | * mounts in the current mount namespace and test to see if the dentry | |
702 | * is a mountpoint. | |
703 | * | |
704 | * The mount_hashtable is not usable in the context because we | |
705 | * need to identify all mounts that may be in the current mount | |
706 | * namespace not just a mount that happens to have some specified | |
707 | * parent mount. | |
708 | */ | |
709 | bool __is_local_mountpoint(struct dentry *dentry) | |
710 | { | |
711 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
712 | struct mount *mnt; | |
713 | bool is_covered = false; | |
714 | ||
715 | if (!d_mountpoint(dentry)) | |
716 | goto out; | |
717 | ||
718 | down_read(&namespace_sem); | |
719 | list_for_each_entry(mnt, &ns->list, mnt_list) { | |
720 | is_covered = (mnt->mnt_mountpoint == dentry); | |
721 | if (is_covered) | |
722 | break; | |
723 | } | |
724 | up_read(&namespace_sem); | |
725 | out: | |
726 | return is_covered; | |
727 | } | |
728 | ||
e2dfa935 | 729 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
84d17192 | 730 | { |
0818bf27 | 731 | struct hlist_head *chain = mp_hash(dentry); |
84d17192 AV |
732 | struct mountpoint *mp; |
733 | ||
0818bf27 | 734 | hlist_for_each_entry(mp, chain, m_hash) { |
84d17192 AV |
735 | if (mp->m_dentry == dentry) { |
736 | /* might be worth a WARN_ON() */ | |
737 | if (d_unlinked(dentry)) | |
738 | return ERR_PTR(-ENOENT); | |
739 | mp->m_count++; | |
740 | return mp; | |
741 | } | |
742 | } | |
e2dfa935 EB |
743 | return NULL; |
744 | } | |
745 | ||
746 | static struct mountpoint *new_mountpoint(struct dentry *dentry) | |
747 | { | |
748 | struct hlist_head *chain = mp_hash(dentry); | |
749 | struct mountpoint *mp; | |
750 | int ret; | |
84d17192 AV |
751 | |
752 | mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); | |
753 | if (!mp) | |
754 | return ERR_PTR(-ENOMEM); | |
755 | ||
eed81007 MS |
756 | ret = d_set_mounted(dentry); |
757 | if (ret) { | |
84d17192 | 758 | kfree(mp); |
eed81007 | 759 | return ERR_PTR(ret); |
84d17192 | 760 | } |
eed81007 | 761 | |
84d17192 AV |
762 | mp->m_dentry = dentry; |
763 | mp->m_count = 1; | |
0818bf27 | 764 | hlist_add_head(&mp->m_hash, chain); |
0a5eb7c8 | 765 | INIT_HLIST_HEAD(&mp->m_list); |
84d17192 AV |
766 | return mp; |
767 | } | |
768 | ||
769 | static void put_mountpoint(struct mountpoint *mp) | |
770 | { | |
771 | if (!--mp->m_count) { | |
772 | struct dentry *dentry = mp->m_dentry; | |
0a5eb7c8 | 773 | BUG_ON(!hlist_empty(&mp->m_list)); |
84d17192 AV |
774 | spin_lock(&dentry->d_lock); |
775 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
776 | spin_unlock(&dentry->d_lock); | |
0818bf27 | 777 | hlist_del(&mp->m_hash); |
84d17192 AV |
778 | kfree(mp); |
779 | } | |
780 | } | |
781 | ||
143c8c91 | 782 | static inline int check_mnt(struct mount *mnt) |
1da177e4 | 783 | { |
6b3286ed | 784 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
785 | } |
786 | ||
99b7db7b NP |
787 | /* |
788 | * vfsmount lock must be held for write | |
789 | */ | |
6b3286ed | 790 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
791 | { |
792 | if (ns) { | |
793 | ns->event = ++event; | |
794 | wake_up_interruptible(&ns->poll); | |
795 | } | |
796 | } | |
797 | ||
99b7db7b NP |
798 | /* |
799 | * vfsmount lock must be held for write | |
800 | */ | |
6b3286ed | 801 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
802 | { |
803 | if (ns && ns->event != event) { | |
804 | ns->event = event; | |
805 | wake_up_interruptible(&ns->poll); | |
806 | } | |
807 | } | |
808 | ||
99b7db7b NP |
809 | /* |
810 | * vfsmount lock must be held for write | |
811 | */ | |
7bdb11de | 812 | static void unhash_mnt(struct mount *mnt) |
419148da | 813 | { |
0714a533 | 814 | mnt->mnt_parent = mnt; |
a73324da | 815 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 816 | list_del_init(&mnt->mnt_child); |
38129a13 | 817 | hlist_del_init_rcu(&mnt->mnt_hash); |
0a5eb7c8 | 818 | hlist_del_init(&mnt->mnt_mp_list); |
84d17192 AV |
819 | put_mountpoint(mnt->mnt_mp); |
820 | mnt->mnt_mp = NULL; | |
1da177e4 LT |
821 | } |
822 | ||
7bdb11de EB |
823 | /* |
824 | * vfsmount lock must be held for write | |
825 | */ | |
826 | static void detach_mnt(struct mount *mnt, struct path *old_path) | |
827 | { | |
828 | old_path->dentry = mnt->mnt_mountpoint; | |
829 | old_path->mnt = &mnt->mnt_parent->mnt; | |
830 | unhash_mnt(mnt); | |
831 | } | |
832 | ||
6a46c573 EB |
833 | /* |
834 | * vfsmount lock must be held for write | |
835 | */ | |
836 | static void umount_mnt(struct mount *mnt) | |
837 | { | |
838 | /* old mountpoint will be dropped when we can do that */ | |
839 | mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint; | |
840 | unhash_mnt(mnt); | |
841 | } | |
842 | ||
99b7db7b NP |
843 | /* |
844 | * vfsmount lock must be held for write | |
845 | */ | |
84d17192 AV |
846 | void mnt_set_mountpoint(struct mount *mnt, |
847 | struct mountpoint *mp, | |
44d964d6 | 848 | struct mount *child_mnt) |
b90fa9ae | 849 | { |
84d17192 | 850 | mp->m_count++; |
3a2393d7 | 851 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
84d17192 | 852 | child_mnt->mnt_mountpoint = dget(mp->m_dentry); |
3a2393d7 | 853 | child_mnt->mnt_parent = mnt; |
84d17192 | 854 | child_mnt->mnt_mp = mp; |
0a5eb7c8 | 855 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
b90fa9ae RP |
856 | } |
857 | ||
99b7db7b NP |
858 | /* |
859 | * vfsmount lock must be held for write | |
860 | */ | |
84d17192 AV |
861 | static void attach_mnt(struct mount *mnt, |
862 | struct mount *parent, | |
863 | struct mountpoint *mp) | |
1da177e4 | 864 | { |
84d17192 | 865 | mnt_set_mountpoint(parent, mp, mnt); |
38129a13 | 866 | hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry)); |
84d17192 | 867 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
b90fa9ae RP |
868 | } |
869 | ||
12a5b529 AV |
870 | static void attach_shadowed(struct mount *mnt, |
871 | struct mount *parent, | |
872 | struct mount *shadows) | |
873 | { | |
874 | if (shadows) { | |
f6f99332 | 875 | hlist_add_behind_rcu(&mnt->mnt_hash, &shadows->mnt_hash); |
12a5b529 AV |
876 | list_add(&mnt->mnt_child, &shadows->mnt_child); |
877 | } else { | |
878 | hlist_add_head_rcu(&mnt->mnt_hash, | |
879 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); | |
880 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
881 | } | |
882 | } | |
883 | ||
b90fa9ae | 884 | /* |
99b7db7b | 885 | * vfsmount lock must be held for write |
b90fa9ae | 886 | */ |
1d6a32ac | 887 | static void commit_tree(struct mount *mnt, struct mount *shadows) |
b90fa9ae | 888 | { |
0714a533 | 889 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 890 | struct mount *m; |
b90fa9ae | 891 | LIST_HEAD(head); |
143c8c91 | 892 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae | 893 | |
0714a533 | 894 | BUG_ON(parent == mnt); |
b90fa9ae | 895 | |
1a4eeaf2 | 896 | list_add_tail(&head, &mnt->mnt_list); |
f7a99c5b | 897 | list_for_each_entry(m, &head, mnt_list) |
143c8c91 | 898 | m->mnt_ns = n; |
f03c6599 | 899 | |
b90fa9ae RP |
900 | list_splice(&head, n->list.prev); |
901 | ||
12a5b529 | 902 | attach_shadowed(mnt, parent, shadows); |
6b3286ed | 903 | touch_mnt_namespace(n); |
1da177e4 LT |
904 | } |
905 | ||
909b0a88 | 906 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
1da177e4 | 907 | { |
6b41d536 AV |
908 | struct list_head *next = p->mnt_mounts.next; |
909 | if (next == &p->mnt_mounts) { | |
1da177e4 | 910 | while (1) { |
909b0a88 | 911 | if (p == root) |
1da177e4 | 912 | return NULL; |
6b41d536 AV |
913 | next = p->mnt_child.next; |
914 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 915 | break; |
0714a533 | 916 | p = p->mnt_parent; |
1da177e4 LT |
917 | } |
918 | } | |
6b41d536 | 919 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
920 | } |
921 | ||
315fc83e | 922 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 923 | { |
6b41d536 AV |
924 | struct list_head *prev = p->mnt_mounts.prev; |
925 | while (prev != &p->mnt_mounts) { | |
926 | p = list_entry(prev, struct mount, mnt_child); | |
927 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
928 | } |
929 | return p; | |
930 | } | |
931 | ||
9d412a43 AV |
932 | struct vfsmount * |
933 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) | |
934 | { | |
b105e270 | 935 | struct mount *mnt; |
9d412a43 AV |
936 | struct dentry *root; |
937 | ||
938 | if (!type) | |
939 | return ERR_PTR(-ENODEV); | |
940 | ||
941 | mnt = alloc_vfsmnt(name); | |
942 | if (!mnt) | |
943 | return ERR_PTR(-ENOMEM); | |
944 | ||
945 | if (flags & MS_KERNMOUNT) | |
b105e270 | 946 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 AV |
947 | |
948 | root = mount_fs(type, flags, name, data); | |
949 | if (IS_ERR(root)) { | |
8ffcb32e | 950 | mnt_free_id(mnt); |
9d412a43 AV |
951 | free_vfsmnt(mnt); |
952 | return ERR_CAST(root); | |
953 | } | |
954 | ||
b105e270 AV |
955 | mnt->mnt.mnt_root = root; |
956 | mnt->mnt.mnt_sb = root->d_sb; | |
a73324da | 957 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
0714a533 | 958 | mnt->mnt_parent = mnt; |
719ea2fb | 959 | lock_mount_hash(); |
39f7c4db | 960 | list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts); |
719ea2fb | 961 | unlock_mount_hash(); |
b105e270 | 962 | return &mnt->mnt; |
9d412a43 AV |
963 | } |
964 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
965 | ||
87129cc0 | 966 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 967 | int flag) |
1da177e4 | 968 | { |
87129cc0 | 969 | struct super_block *sb = old->mnt.mnt_sb; |
be34d1a3 DH |
970 | struct mount *mnt; |
971 | int err; | |
1da177e4 | 972 | |
be34d1a3 DH |
973 | mnt = alloc_vfsmnt(old->mnt_devname); |
974 | if (!mnt) | |
975 | return ERR_PTR(-ENOMEM); | |
719f5d7f | 976 | |
7a472ef4 | 977 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
be34d1a3 DH |
978 | mnt->mnt_group_id = 0; /* not a peer of original */ |
979 | else | |
980 | mnt->mnt_group_id = old->mnt_group_id; | |
b90fa9ae | 981 | |
be34d1a3 DH |
982 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
983 | err = mnt_alloc_group_id(mnt); | |
984 | if (err) | |
985 | goto out_free; | |
1da177e4 | 986 | } |
be34d1a3 | 987 | |
f2ebb3a9 | 988 | mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); |
132c94e3 | 989 | /* Don't allow unprivileged users to change mount flags */ |
9566d674 EB |
990 | if (flag & CL_UNPRIVILEGED) { |
991 | mnt->mnt.mnt_flags |= MNT_LOCK_ATIME; | |
992 | ||
993 | if (mnt->mnt.mnt_flags & MNT_READONLY) | |
994 | mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; | |
995 | ||
996 | if (mnt->mnt.mnt_flags & MNT_NODEV) | |
997 | mnt->mnt.mnt_flags |= MNT_LOCK_NODEV; | |
998 | ||
999 | if (mnt->mnt.mnt_flags & MNT_NOSUID) | |
1000 | mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID; | |
1001 | ||
1002 | if (mnt->mnt.mnt_flags & MNT_NOEXEC) | |
1003 | mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC; | |
1004 | } | |
132c94e3 | 1005 | |
5ff9d8a6 | 1006 | /* Don't allow unprivileged users to reveal what is under a mount */ |
381cacb1 EB |
1007 | if ((flag & CL_UNPRIVILEGED) && |
1008 | (!(flag & CL_EXPIRE) || list_empty(&old->mnt_expire))) | |
5ff9d8a6 EB |
1009 | mnt->mnt.mnt_flags |= MNT_LOCKED; |
1010 | ||
be34d1a3 DH |
1011 | atomic_inc(&sb->s_active); |
1012 | mnt->mnt.mnt_sb = sb; | |
1013 | mnt->mnt.mnt_root = dget(root); | |
1014 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1015 | mnt->mnt_parent = mnt; | |
719ea2fb | 1016 | lock_mount_hash(); |
be34d1a3 | 1017 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
719ea2fb | 1018 | unlock_mount_hash(); |
be34d1a3 | 1019 | |
7a472ef4 EB |
1020 | if ((flag & CL_SLAVE) || |
1021 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { | |
be34d1a3 DH |
1022 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
1023 | mnt->mnt_master = old; | |
1024 | CLEAR_MNT_SHARED(mnt); | |
1025 | } else if (!(flag & CL_PRIVATE)) { | |
1026 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) | |
1027 | list_add(&mnt->mnt_share, &old->mnt_share); | |
1028 | if (IS_MNT_SLAVE(old)) | |
1029 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
1030 | mnt->mnt_master = old->mnt_master; | |
1031 | } | |
1032 | if (flag & CL_MAKE_SHARED) | |
1033 | set_mnt_shared(mnt); | |
1034 | ||
1035 | /* stick the duplicate mount on the same expiry list | |
1036 | * as the original if that was on one */ | |
1037 | if (flag & CL_EXPIRE) { | |
1038 | if (!list_empty(&old->mnt_expire)) | |
1039 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
1040 | } | |
1041 | ||
cb338d06 | 1042 | return mnt; |
719f5d7f MS |
1043 | |
1044 | out_free: | |
8ffcb32e | 1045 | mnt_free_id(mnt); |
719f5d7f | 1046 | free_vfsmnt(mnt); |
be34d1a3 | 1047 | return ERR_PTR(err); |
1da177e4 LT |
1048 | } |
1049 | ||
9ea459e1 AV |
1050 | static void cleanup_mnt(struct mount *mnt) |
1051 | { | |
1052 | /* | |
1053 | * This probably indicates that somebody messed | |
1054 | * up a mnt_want/drop_write() pair. If this | |
1055 | * happens, the filesystem was probably unable | |
1056 | * to make r/w->r/o transitions. | |
1057 | */ | |
1058 | /* | |
1059 | * The locking used to deal with mnt_count decrement provides barriers, | |
1060 | * so mnt_get_writers() below is safe. | |
1061 | */ | |
1062 | WARN_ON(mnt_get_writers(mnt)); | |
1063 | if (unlikely(mnt->mnt_pins.first)) | |
1064 | mnt_pin_kill(mnt); | |
1065 | fsnotify_vfsmount_delete(&mnt->mnt); | |
1066 | dput(mnt->mnt.mnt_root); | |
1067 | deactivate_super(mnt->mnt.mnt_sb); | |
1068 | mnt_free_id(mnt); | |
1069 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); | |
1070 | } | |
1071 | ||
1072 | static void __cleanup_mnt(struct rcu_head *head) | |
1073 | { | |
1074 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); | |
1075 | } | |
1076 | ||
1077 | static LLIST_HEAD(delayed_mntput_list); | |
1078 | static void delayed_mntput(struct work_struct *unused) | |
1079 | { | |
1080 | struct llist_node *node = llist_del_all(&delayed_mntput_list); | |
1081 | struct llist_node *next; | |
1082 | ||
1083 | for (; node; node = next) { | |
1084 | next = llist_next(node); | |
1085 | cleanup_mnt(llist_entry(node, struct mount, mnt_llist)); | |
1086 | } | |
1087 | } | |
1088 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); | |
1089 | ||
900148dc | 1090 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 1091 | { |
48a066e7 AV |
1092 | rcu_read_lock(); |
1093 | mnt_add_count(mnt, -1); | |
1094 | if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */ | |
1095 | rcu_read_unlock(); | |
f03c6599 | 1096 | return; |
b3e19d92 | 1097 | } |
719ea2fb | 1098 | lock_mount_hash(); |
b3e19d92 | 1099 | if (mnt_get_count(mnt)) { |
48a066e7 | 1100 | rcu_read_unlock(); |
719ea2fb | 1101 | unlock_mount_hash(); |
99b7db7b NP |
1102 | return; |
1103 | } | |
48a066e7 AV |
1104 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
1105 | rcu_read_unlock(); | |
1106 | unlock_mount_hash(); | |
1107 | return; | |
1108 | } | |
1109 | mnt->mnt.mnt_flags |= MNT_DOOMED; | |
1110 | rcu_read_unlock(); | |
962830df | 1111 | |
39f7c4db | 1112 | list_del(&mnt->mnt_instance); |
ce07d891 EB |
1113 | |
1114 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { | |
1115 | struct mount *p, *tmp; | |
1116 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { | |
1117 | umount_mnt(p); | |
1118 | } | |
1119 | } | |
719ea2fb | 1120 | unlock_mount_hash(); |
649a795a | 1121 | |
9ea459e1 AV |
1122 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
1123 | struct task_struct *task = current; | |
1124 | if (likely(!(task->flags & PF_KTHREAD))) { | |
1125 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); | |
1126 | if (!task_work_add(task, &mnt->mnt_rcu, true)) | |
1127 | return; | |
1128 | } | |
1129 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) | |
1130 | schedule_delayed_work(&delayed_mntput_work, 1); | |
1131 | return; | |
1132 | } | |
1133 | cleanup_mnt(mnt); | |
b3e19d92 | 1134 | } |
b3e19d92 NP |
1135 | |
1136 | void mntput(struct vfsmount *mnt) | |
1137 | { | |
1138 | if (mnt) { | |
863d684f | 1139 | struct mount *m = real_mount(mnt); |
b3e19d92 | 1140 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
863d684f AV |
1141 | if (unlikely(m->mnt_expiry_mark)) |
1142 | m->mnt_expiry_mark = 0; | |
1143 | mntput_no_expire(m); | |
b3e19d92 NP |
1144 | } |
1145 | } | |
1146 | EXPORT_SYMBOL(mntput); | |
1147 | ||
1148 | struct vfsmount *mntget(struct vfsmount *mnt) | |
1149 | { | |
1150 | if (mnt) | |
83adc753 | 1151 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
1152 | return mnt; |
1153 | } | |
1154 | EXPORT_SYMBOL(mntget); | |
1155 | ||
3064c356 | 1156 | struct vfsmount *mnt_clone_internal(struct path *path) |
7b7b1ace | 1157 | { |
3064c356 AV |
1158 | struct mount *p; |
1159 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); | |
1160 | if (IS_ERR(p)) | |
1161 | return ERR_CAST(p); | |
1162 | p->mnt.mnt_flags |= MNT_INTERNAL; | |
1163 | return &p->mnt; | |
7b7b1ace | 1164 | } |
1da177e4 | 1165 | |
b3b304a2 MS |
1166 | static inline void mangle(struct seq_file *m, const char *s) |
1167 | { | |
1168 | seq_escape(m, s, " \t\n\\"); | |
1169 | } | |
1170 | ||
1171 | /* | |
1172 | * Simple .show_options callback for filesystems which don't want to | |
1173 | * implement more complex mount option showing. | |
1174 | * | |
1175 | * See also save_mount_options(). | |
1176 | */ | |
34c80b1d | 1177 | int generic_show_options(struct seq_file *m, struct dentry *root) |
b3b304a2 | 1178 | { |
2a32cebd AV |
1179 | const char *options; |
1180 | ||
1181 | rcu_read_lock(); | |
34c80b1d | 1182 | options = rcu_dereference(root->d_sb->s_options); |
b3b304a2 MS |
1183 | |
1184 | if (options != NULL && options[0]) { | |
1185 | seq_putc(m, ','); | |
1186 | mangle(m, options); | |
1187 | } | |
2a32cebd | 1188 | rcu_read_unlock(); |
b3b304a2 MS |
1189 | |
1190 | return 0; | |
1191 | } | |
1192 | EXPORT_SYMBOL(generic_show_options); | |
1193 | ||
1194 | /* | |
1195 | * If filesystem uses generic_show_options(), this function should be | |
1196 | * called from the fill_super() callback. | |
1197 | * | |
1198 | * The .remount_fs callback usually needs to be handled in a special | |
1199 | * way, to make sure, that previous options are not overwritten if the | |
1200 | * remount fails. | |
1201 | * | |
1202 | * Also note, that if the filesystem's .remount_fs function doesn't | |
1203 | * reset all options to their default value, but changes only newly | |
1204 | * given options, then the displayed options will not reflect reality | |
1205 | * any more. | |
1206 | */ | |
1207 | void save_mount_options(struct super_block *sb, char *options) | |
1208 | { | |
2a32cebd AV |
1209 | BUG_ON(sb->s_options); |
1210 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
1211 | } |
1212 | EXPORT_SYMBOL(save_mount_options); | |
1213 | ||
2a32cebd AV |
1214 | void replace_mount_options(struct super_block *sb, char *options) |
1215 | { | |
1216 | char *old = sb->s_options; | |
1217 | rcu_assign_pointer(sb->s_options, options); | |
1218 | if (old) { | |
1219 | synchronize_rcu(); | |
1220 | kfree(old); | |
1221 | } | |
1222 | } | |
1223 | EXPORT_SYMBOL(replace_mount_options); | |
1224 | ||
a1a2c409 | 1225 | #ifdef CONFIG_PROC_FS |
0226f492 | 1226 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
1da177e4 LT |
1227 | static void *m_start(struct seq_file *m, loff_t *pos) |
1228 | { | |
ede1bf0d | 1229 | struct proc_mounts *p = m->private; |
1da177e4 | 1230 | |
390c6843 | 1231 | down_read(&namespace_sem); |
c7999c36 AV |
1232 | if (p->cached_event == p->ns->event) { |
1233 | void *v = p->cached_mount; | |
1234 | if (*pos == p->cached_index) | |
1235 | return v; | |
1236 | if (*pos == p->cached_index + 1) { | |
1237 | v = seq_list_next(v, &p->ns->list, &p->cached_index); | |
1238 | return p->cached_mount = v; | |
1239 | } | |
1240 | } | |
1241 | ||
1242 | p->cached_event = p->ns->event; | |
1243 | p->cached_mount = seq_list_start(&p->ns->list, *pos); | |
1244 | p->cached_index = *pos; | |
1245 | return p->cached_mount; | |
1da177e4 LT |
1246 | } |
1247 | ||
1248 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
1249 | { | |
ede1bf0d | 1250 | struct proc_mounts *p = m->private; |
b0765fb8 | 1251 | |
c7999c36 AV |
1252 | p->cached_mount = seq_list_next(v, &p->ns->list, pos); |
1253 | p->cached_index = *pos; | |
1254 | return p->cached_mount; | |
1da177e4 LT |
1255 | } |
1256 | ||
1257 | static void m_stop(struct seq_file *m, void *v) | |
1258 | { | |
390c6843 | 1259 | up_read(&namespace_sem); |
1da177e4 LT |
1260 | } |
1261 | ||
0226f492 | 1262 | static int m_show(struct seq_file *m, void *v) |
2d4d4864 | 1263 | { |
ede1bf0d | 1264 | struct proc_mounts *p = m->private; |
1a4eeaf2 | 1265 | struct mount *r = list_entry(v, struct mount, mnt_list); |
0226f492 | 1266 | return p->show(m, &r->mnt); |
1da177e4 LT |
1267 | } |
1268 | ||
a1a2c409 | 1269 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1270 | .start = m_start, |
1271 | .next = m_next, | |
1272 | .stop = m_stop, | |
0226f492 | 1273 | .show = m_show, |
b4629fe2 | 1274 | }; |
a1a2c409 | 1275 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1276 | |
1da177e4 LT |
1277 | /** |
1278 | * may_umount_tree - check if a mount tree is busy | |
1279 | * @mnt: root of mount tree | |
1280 | * | |
1281 | * This is called to check if a tree of mounts has any | |
1282 | * open files, pwds, chroots or sub mounts that are | |
1283 | * busy. | |
1284 | */ | |
909b0a88 | 1285 | int may_umount_tree(struct vfsmount *m) |
1da177e4 | 1286 | { |
909b0a88 | 1287 | struct mount *mnt = real_mount(m); |
36341f64 RP |
1288 | int actual_refs = 0; |
1289 | int minimum_refs = 0; | |
315fc83e | 1290 | struct mount *p; |
909b0a88 | 1291 | BUG_ON(!m); |
1da177e4 | 1292 | |
b3e19d92 | 1293 | /* write lock needed for mnt_get_count */ |
719ea2fb | 1294 | lock_mount_hash(); |
909b0a88 | 1295 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
83adc753 | 1296 | actual_refs += mnt_get_count(p); |
1da177e4 | 1297 | minimum_refs += 2; |
1da177e4 | 1298 | } |
719ea2fb | 1299 | unlock_mount_hash(); |
1da177e4 LT |
1300 | |
1301 | if (actual_refs > minimum_refs) | |
e3474a8e | 1302 | return 0; |
1da177e4 | 1303 | |
e3474a8e | 1304 | return 1; |
1da177e4 LT |
1305 | } |
1306 | ||
1307 | EXPORT_SYMBOL(may_umount_tree); | |
1308 | ||
1309 | /** | |
1310 | * may_umount - check if a mount point is busy | |
1311 | * @mnt: root of mount | |
1312 | * | |
1313 | * This is called to check if a mount point has any | |
1314 | * open files, pwds, chroots or sub mounts. If the | |
1315 | * mount has sub mounts this will return busy | |
1316 | * regardless of whether the sub mounts are busy. | |
1317 | * | |
1318 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1319 | * give false negatives. The main reason why it's here is that we need | |
1320 | * a non-destructive way to look for easily umountable filesystems. | |
1321 | */ | |
1322 | int may_umount(struct vfsmount *mnt) | |
1323 | { | |
e3474a8e | 1324 | int ret = 1; |
8ad08d8a | 1325 | down_read(&namespace_sem); |
719ea2fb | 1326 | lock_mount_hash(); |
1ab59738 | 1327 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1328 | ret = 0; |
719ea2fb | 1329 | unlock_mount_hash(); |
8ad08d8a | 1330 | up_read(&namespace_sem); |
a05964f3 | 1331 | return ret; |
1da177e4 LT |
1332 | } |
1333 | ||
1334 | EXPORT_SYMBOL(may_umount); | |
1335 | ||
38129a13 | 1336 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
e3197d83 | 1337 | |
97216be0 | 1338 | static void namespace_unlock(void) |
70fbcdf4 | 1339 | { |
a3b3c562 | 1340 | struct hlist_head head; |
97216be0 | 1341 | |
a3b3c562 | 1342 | hlist_move_list(&unmounted, &head); |
97216be0 | 1343 | |
97216be0 AV |
1344 | up_write(&namespace_sem); |
1345 | ||
a3b3c562 EB |
1346 | if (likely(hlist_empty(&head))) |
1347 | return; | |
1348 | ||
48a066e7 AV |
1349 | synchronize_rcu(); |
1350 | ||
87b95ce0 | 1351 | group_pin_kill(&head); |
70fbcdf4 RP |
1352 | } |
1353 | ||
97216be0 | 1354 | static inline void namespace_lock(void) |
e3197d83 | 1355 | { |
97216be0 | 1356 | down_write(&namespace_sem); |
e3197d83 AV |
1357 | } |
1358 | ||
e819f152 EB |
1359 | enum umount_tree_flags { |
1360 | UMOUNT_SYNC = 1, | |
1361 | UMOUNT_PROPAGATE = 2, | |
e0c9c0af | 1362 | UMOUNT_CONNECTED = 4, |
e819f152 | 1363 | }; |
99b7db7b | 1364 | /* |
48a066e7 | 1365 | * mount_lock must be held |
99b7db7b NP |
1366 | * namespace_sem must be held for write |
1367 | */ | |
e819f152 | 1368 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
1da177e4 | 1369 | { |
c003b26f | 1370 | LIST_HEAD(tmp_list); |
315fc83e | 1371 | struct mount *p; |
1da177e4 | 1372 | |
5d88457e EB |
1373 | if (how & UMOUNT_PROPAGATE) |
1374 | propagate_mount_unlock(mnt); | |
1375 | ||
c003b26f | 1376 | /* Gather the mounts to umount */ |
590ce4bc EB |
1377 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1378 | p->mnt.mnt_flags |= MNT_UMOUNT; | |
c003b26f | 1379 | list_move(&p->mnt_list, &tmp_list); |
590ce4bc | 1380 | } |
1da177e4 | 1381 | |
411a938b | 1382 | /* Hide the mounts from mnt_mounts */ |
c003b26f | 1383 | list_for_each_entry(p, &tmp_list, mnt_list) { |
88b368f2 | 1384 | list_del_init(&p->mnt_child); |
c003b26f | 1385 | } |
88b368f2 | 1386 | |
c003b26f | 1387 | /* Add propogated mounts to the tmp_list */ |
e819f152 | 1388 | if (how & UMOUNT_PROPAGATE) |
7b8a53fd | 1389 | propagate_umount(&tmp_list); |
a05964f3 | 1390 | |
c003b26f | 1391 | while (!list_empty(&tmp_list)) { |
ce07d891 | 1392 | bool disconnect; |
c003b26f | 1393 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
6776db3d | 1394 | list_del_init(&p->mnt_expire); |
1a4eeaf2 | 1395 | list_del_init(&p->mnt_list); |
143c8c91 AV |
1396 | __touch_mnt_namespace(p->mnt_ns); |
1397 | p->mnt_ns = NULL; | |
e819f152 | 1398 | if (how & UMOUNT_SYNC) |
48a066e7 | 1399 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
87b95ce0 | 1400 | |
e0c9c0af EB |
1401 | disconnect = !(((how & UMOUNT_CONNECTED) && |
1402 | mnt_has_parent(p) && | |
1403 | (p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) || | |
1404 | IS_MNT_LOCKED_AND_LAZY(p)); | |
ce07d891 EB |
1405 | |
1406 | pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, | |
1407 | disconnect ? &unmounted : NULL); | |
676da58d | 1408 | if (mnt_has_parent(p)) { |
81b6b061 | 1409 | mnt_add_count(p->mnt_parent, -1); |
ce07d891 EB |
1410 | if (!disconnect) { |
1411 | /* Don't forget about p */ | |
1412 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); | |
1413 | } else { | |
1414 | umount_mnt(p); | |
1415 | } | |
7c4b93d8 | 1416 | } |
0f0afb1d | 1417 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
1418 | } |
1419 | } | |
1420 | ||
b54b9be7 | 1421 | static void shrink_submounts(struct mount *mnt); |
c35038be | 1422 | |
1ab59738 | 1423 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1424 | { |
1ab59738 | 1425 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 LT |
1426 | int retval; |
1427 | ||
1ab59738 | 1428 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1429 | if (retval) |
1430 | return retval; | |
1431 | ||
1432 | /* | |
1433 | * Allow userspace to request a mountpoint be expired rather than | |
1434 | * unmounting unconditionally. Unmount only happens if: | |
1435 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1436 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1437 | */ | |
1438 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1439 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1440 | flags & (MNT_FORCE | MNT_DETACH)) |
1441 | return -EINVAL; | |
1442 | ||
b3e19d92 NP |
1443 | /* |
1444 | * probably don't strictly need the lock here if we examined | |
1445 | * all race cases, but it's a slowpath. | |
1446 | */ | |
719ea2fb | 1447 | lock_mount_hash(); |
83adc753 | 1448 | if (mnt_get_count(mnt) != 2) { |
719ea2fb | 1449 | unlock_mount_hash(); |
1da177e4 | 1450 | return -EBUSY; |
b3e19d92 | 1451 | } |
719ea2fb | 1452 | unlock_mount_hash(); |
1da177e4 | 1453 | |
863d684f | 1454 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
1da177e4 LT |
1455 | return -EAGAIN; |
1456 | } | |
1457 | ||
1458 | /* | |
1459 | * If we may have to abort operations to get out of this | |
1460 | * mount, and they will themselves hold resources we must | |
1461 | * allow the fs to do things. In the Unix tradition of | |
1462 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1463 | * might fail to complete on the first run through as other tasks | |
1464 | * must return, and the like. Thats for the mount program to worry | |
1465 | * about for the moment. | |
1466 | */ | |
1467 | ||
42faad99 | 1468 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1469 | sb->s_op->umount_begin(sb); |
42faad99 | 1470 | } |
1da177e4 LT |
1471 | |
1472 | /* | |
1473 | * No sense to grab the lock for this test, but test itself looks | |
1474 | * somewhat bogus. Suggestions for better replacement? | |
1475 | * Ho-hum... In principle, we might treat that as umount + switch | |
1476 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1477 | * Actually it makes sense, especially if rootfs would contain a | |
1478 | * /reboot - static binary that would close all descriptors and | |
1479 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1480 | */ | |
1ab59738 | 1481 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1482 | /* |
1483 | * Special case for "unmounting" root ... | |
1484 | * we just try to remount it readonly. | |
1485 | */ | |
a1480dcc AL |
1486 | if (!capable(CAP_SYS_ADMIN)) |
1487 | return -EPERM; | |
1da177e4 | 1488 | down_write(&sb->s_umount); |
4aa98cf7 | 1489 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1490 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1491 | up_write(&sb->s_umount); |
1492 | return retval; | |
1493 | } | |
1494 | ||
97216be0 | 1495 | namespace_lock(); |
719ea2fb | 1496 | lock_mount_hash(); |
5addc5dd | 1497 | event++; |
1da177e4 | 1498 | |
48a066e7 | 1499 | if (flags & MNT_DETACH) { |
1a4eeaf2 | 1500 | if (!list_empty(&mnt->mnt_list)) |
e819f152 | 1501 | umount_tree(mnt, UMOUNT_PROPAGATE); |
1da177e4 | 1502 | retval = 0; |
48a066e7 AV |
1503 | } else { |
1504 | shrink_submounts(mnt); | |
1505 | retval = -EBUSY; | |
1506 | if (!propagate_mount_busy(mnt, 2)) { | |
1507 | if (!list_empty(&mnt->mnt_list)) | |
e819f152 | 1508 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
48a066e7 AV |
1509 | retval = 0; |
1510 | } | |
1da177e4 | 1511 | } |
719ea2fb | 1512 | unlock_mount_hash(); |
e3197d83 | 1513 | namespace_unlock(); |
1da177e4 LT |
1514 | return retval; |
1515 | } | |
1516 | ||
80b5dce8 EB |
1517 | /* |
1518 | * __detach_mounts - lazily unmount all mounts on the specified dentry | |
1519 | * | |
1520 | * During unlink, rmdir, and d_drop it is possible to loose the path | |
1521 | * to an existing mountpoint, and wind up leaking the mount. | |
1522 | * detach_mounts allows lazily unmounting those mounts instead of | |
1523 | * leaking them. | |
1524 | * | |
1525 | * The caller may hold dentry->d_inode->i_mutex. | |
1526 | */ | |
1527 | void __detach_mounts(struct dentry *dentry) | |
1528 | { | |
1529 | struct mountpoint *mp; | |
1530 | struct mount *mnt; | |
1531 | ||
1532 | namespace_lock(); | |
1533 | mp = lookup_mountpoint(dentry); | |
f53e5797 | 1534 | if (IS_ERR_OR_NULL(mp)) |
80b5dce8 EB |
1535 | goto out_unlock; |
1536 | ||
1537 | lock_mount_hash(); | |
1538 | while (!hlist_empty(&mp->m_list)) { | |
1539 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); | |
ce07d891 EB |
1540 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
1541 | struct mount *p, *tmp; | |
1542 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { | |
1543 | hlist_add_head(&p->mnt_umount.s_list, &unmounted); | |
1544 | umount_mnt(p); | |
1545 | } | |
1546 | } | |
e0c9c0af | 1547 | else umount_tree(mnt, UMOUNT_CONNECTED); |
80b5dce8 EB |
1548 | } |
1549 | unlock_mount_hash(); | |
1550 | put_mountpoint(mp); | |
1551 | out_unlock: | |
1552 | namespace_unlock(); | |
1553 | } | |
1554 | ||
9b40bc90 AV |
1555 | /* |
1556 | * Is the caller allowed to modify his namespace? | |
1557 | */ | |
1558 | static inline bool may_mount(void) | |
1559 | { | |
1560 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); | |
1561 | } | |
1562 | ||
1da177e4 LT |
1563 | /* |
1564 | * Now umount can handle mount points as well as block devices. | |
1565 | * This is important for filesystems which use unnamed block devices. | |
1566 | * | |
1567 | * We now support a flag for forced unmount like the other 'big iron' | |
1568 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1569 | */ | |
1570 | ||
bdc480e3 | 1571 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1572 | { |
2d8f3038 | 1573 | struct path path; |
900148dc | 1574 | struct mount *mnt; |
1da177e4 | 1575 | int retval; |
db1f05bb | 1576 | int lookup_flags = 0; |
1da177e4 | 1577 | |
db1f05bb MS |
1578 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
1579 | return -EINVAL; | |
1580 | ||
9b40bc90 AV |
1581 | if (!may_mount()) |
1582 | return -EPERM; | |
1583 | ||
db1f05bb MS |
1584 | if (!(flags & UMOUNT_NOFOLLOW)) |
1585 | lookup_flags |= LOOKUP_FOLLOW; | |
1586 | ||
197df04c | 1587 | retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path); |
1da177e4 LT |
1588 | if (retval) |
1589 | goto out; | |
900148dc | 1590 | mnt = real_mount(path.mnt); |
1da177e4 | 1591 | retval = -EINVAL; |
2d8f3038 | 1592 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1593 | goto dput_and_out; |
143c8c91 | 1594 | if (!check_mnt(mnt)) |
1da177e4 | 1595 | goto dput_and_out; |
5ff9d8a6 EB |
1596 | if (mnt->mnt.mnt_flags & MNT_LOCKED) |
1597 | goto dput_and_out; | |
b2f5d4dc EB |
1598 | retval = -EPERM; |
1599 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) | |
1600 | goto dput_and_out; | |
1da177e4 | 1601 | |
900148dc | 1602 | retval = do_umount(mnt, flags); |
1da177e4 | 1603 | dput_and_out: |
429731b1 | 1604 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 | 1605 | dput(path.dentry); |
900148dc | 1606 | mntput_no_expire(mnt); |
1da177e4 LT |
1607 | out: |
1608 | return retval; | |
1609 | } | |
1610 | ||
1611 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1612 | ||
1613 | /* | |
b58fed8b | 1614 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1615 | */ |
bdc480e3 | 1616 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1617 | { |
b58fed8b | 1618 | return sys_umount(name, 0); |
1da177e4 LT |
1619 | } |
1620 | ||
1621 | #endif | |
1622 | ||
4ce5d2b1 | 1623 | static bool is_mnt_ns_file(struct dentry *dentry) |
8823c079 | 1624 | { |
4ce5d2b1 | 1625 | /* Is this a proxy for a mount namespace? */ |
e149ed2b AV |
1626 | return dentry->d_op == &ns_dentry_operations && |
1627 | dentry->d_fsdata == &mntns_operations; | |
4ce5d2b1 EB |
1628 | } |
1629 | ||
58be2825 AV |
1630 | struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
1631 | { | |
1632 | return container_of(ns, struct mnt_namespace, ns); | |
1633 | } | |
1634 | ||
4ce5d2b1 EB |
1635 | static bool mnt_ns_loop(struct dentry *dentry) |
1636 | { | |
1637 | /* Could bind mounting the mount namespace inode cause a | |
1638 | * mount namespace loop? | |
1639 | */ | |
1640 | struct mnt_namespace *mnt_ns; | |
1641 | if (!is_mnt_ns_file(dentry)) | |
1642 | return false; | |
1643 | ||
f77c8014 | 1644 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
8823c079 EB |
1645 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
1646 | } | |
1647 | ||
87129cc0 | 1648 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1649 | int flag) |
1da177e4 | 1650 | { |
84d17192 | 1651 | struct mount *res, *p, *q, *r, *parent; |
1da177e4 | 1652 | |
4ce5d2b1 EB |
1653 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
1654 | return ERR_PTR(-EINVAL); | |
1655 | ||
1656 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) | |
be34d1a3 | 1657 | return ERR_PTR(-EINVAL); |
9676f0c6 | 1658 | |
36341f64 | 1659 | res = q = clone_mnt(mnt, dentry, flag); |
be34d1a3 DH |
1660 | if (IS_ERR(q)) |
1661 | return q; | |
1662 | ||
a73324da | 1663 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1664 | |
1665 | p = mnt; | |
6b41d536 | 1666 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1667 | struct mount *s; |
7ec02ef1 | 1668 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1669 | continue; |
1670 | ||
909b0a88 | 1671 | for (s = r; s; s = next_mnt(s, r)) { |
12a5b529 | 1672 | struct mount *t = NULL; |
4ce5d2b1 EB |
1673 | if (!(flag & CL_COPY_UNBINDABLE) && |
1674 | IS_MNT_UNBINDABLE(s)) { | |
1675 | s = skip_mnt_tree(s); | |
1676 | continue; | |
1677 | } | |
1678 | if (!(flag & CL_COPY_MNT_NS_FILE) && | |
1679 | is_mnt_ns_file(s->mnt.mnt_root)) { | |
9676f0c6 RP |
1680 | s = skip_mnt_tree(s); |
1681 | continue; | |
1682 | } | |
0714a533 AV |
1683 | while (p != s->mnt_parent) { |
1684 | p = p->mnt_parent; | |
1685 | q = q->mnt_parent; | |
1da177e4 | 1686 | } |
87129cc0 | 1687 | p = s; |
84d17192 | 1688 | parent = q; |
87129cc0 | 1689 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
be34d1a3 DH |
1690 | if (IS_ERR(q)) |
1691 | goto out; | |
719ea2fb | 1692 | lock_mount_hash(); |
1a4eeaf2 | 1693 | list_add_tail(&q->mnt_list, &res->mnt_list); |
12a5b529 AV |
1694 | mnt_set_mountpoint(parent, p->mnt_mp, q); |
1695 | if (!list_empty(&parent->mnt_mounts)) { | |
1696 | t = list_last_entry(&parent->mnt_mounts, | |
1697 | struct mount, mnt_child); | |
1698 | if (t->mnt_mp != p->mnt_mp) | |
1699 | t = NULL; | |
1700 | } | |
1701 | attach_shadowed(q, parent, t); | |
719ea2fb | 1702 | unlock_mount_hash(); |
1da177e4 LT |
1703 | } |
1704 | } | |
1705 | return res; | |
be34d1a3 | 1706 | out: |
1da177e4 | 1707 | if (res) { |
719ea2fb | 1708 | lock_mount_hash(); |
e819f152 | 1709 | umount_tree(res, UMOUNT_SYNC); |
719ea2fb | 1710 | unlock_mount_hash(); |
1da177e4 | 1711 | } |
be34d1a3 | 1712 | return q; |
1da177e4 LT |
1713 | } |
1714 | ||
be34d1a3 DH |
1715 | /* Caller should check returned pointer for errors */ |
1716 | ||
589ff870 | 1717 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 | 1718 | { |
cb338d06 | 1719 | struct mount *tree; |
97216be0 | 1720 | namespace_lock(); |
cd4a4017 EB |
1721 | if (!check_mnt(real_mount(path->mnt))) |
1722 | tree = ERR_PTR(-EINVAL); | |
1723 | else | |
1724 | tree = copy_tree(real_mount(path->mnt), path->dentry, | |
1725 | CL_COPY_ALL | CL_PRIVATE); | |
328e6d90 | 1726 | namespace_unlock(); |
be34d1a3 | 1727 | if (IS_ERR(tree)) |
52e220d3 | 1728 | return ERR_CAST(tree); |
be34d1a3 | 1729 | return &tree->mnt; |
8aec0809 AV |
1730 | } |
1731 | ||
1732 | void drop_collected_mounts(struct vfsmount *mnt) | |
1733 | { | |
97216be0 | 1734 | namespace_lock(); |
719ea2fb | 1735 | lock_mount_hash(); |
e819f152 | 1736 | umount_tree(real_mount(mnt), UMOUNT_SYNC); |
719ea2fb | 1737 | unlock_mount_hash(); |
3ab6abee | 1738 | namespace_unlock(); |
8aec0809 AV |
1739 | } |
1740 | ||
c771d683 MS |
1741 | /** |
1742 | * clone_private_mount - create a private clone of a path | |
1743 | * | |
1744 | * This creates a new vfsmount, which will be the clone of @path. The new will | |
1745 | * not be attached anywhere in the namespace and will be private (i.e. changes | |
1746 | * to the originating mount won't be propagated into this). | |
1747 | * | |
1748 | * Release with mntput(). | |
1749 | */ | |
1750 | struct vfsmount *clone_private_mount(struct path *path) | |
1751 | { | |
1752 | struct mount *old_mnt = real_mount(path->mnt); | |
1753 | struct mount *new_mnt; | |
1754 | ||
1755 | if (IS_MNT_UNBINDABLE(old_mnt)) | |
1756 | return ERR_PTR(-EINVAL); | |
1757 | ||
1758 | down_read(&namespace_sem); | |
1759 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); | |
1760 | up_read(&namespace_sem); | |
1761 | if (IS_ERR(new_mnt)) | |
1762 | return ERR_CAST(new_mnt); | |
1763 | ||
1764 | return &new_mnt->mnt; | |
1765 | } | |
1766 | EXPORT_SYMBOL_GPL(clone_private_mount); | |
1767 | ||
1f707137 AV |
1768 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1769 | struct vfsmount *root) | |
1770 | { | |
1a4eeaf2 | 1771 | struct mount *mnt; |
1f707137 AV |
1772 | int res = f(root, arg); |
1773 | if (res) | |
1774 | return res; | |
1a4eeaf2 AV |
1775 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
1776 | res = f(&mnt->mnt, arg); | |
1f707137 AV |
1777 | if (res) |
1778 | return res; | |
1779 | } | |
1780 | return 0; | |
1781 | } | |
1782 | ||
4b8b21f4 | 1783 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 1784 | { |
315fc83e | 1785 | struct mount *p; |
719f5d7f | 1786 | |
909b0a88 | 1787 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
fc7be130 | 1788 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
4b8b21f4 | 1789 | mnt_release_group_id(p); |
719f5d7f MS |
1790 | } |
1791 | } | |
1792 | ||
4b8b21f4 | 1793 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 1794 | { |
315fc83e | 1795 | struct mount *p; |
719f5d7f | 1796 | |
909b0a88 | 1797 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
fc7be130 | 1798 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
4b8b21f4 | 1799 | int err = mnt_alloc_group_id(p); |
719f5d7f | 1800 | if (err) { |
4b8b21f4 | 1801 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
1802 | return err; |
1803 | } | |
1804 | } | |
1805 | } | |
1806 | ||
1807 | return 0; | |
1808 | } | |
1809 | ||
b90fa9ae RP |
1810 | /* |
1811 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1812 | * @nd : place the mount tree @source_mnt is attached |
1813 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1814 | * store the parent mount and mountpoint dentry. | |
1815 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1816 | * |
1817 | * NOTE: in the table below explains the semantics when a source mount | |
1818 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1819 | * --------------------------------------------------------------------------- |
1820 | * | BIND MOUNT OPERATION | | |
1821 | * |************************************************************************** | |
1822 | * | source-->| shared | private | slave | unbindable | | |
1823 | * | dest | | | | | | |
1824 | * | | | | | | | | |
1825 | * | v | | | | | | |
1826 | * |************************************************************************** | |
1827 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1828 | * | | | | | | | |
1829 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1830 | * *************************************************************************** | |
b90fa9ae RP |
1831 | * A bind operation clones the source mount and mounts the clone on the |
1832 | * destination mount. | |
1833 | * | |
1834 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1835 | * tree of the destination mount and the cloned mount is added to | |
1836 | * the peer group of the source mount. | |
1837 | * (+) the cloned mount is created under the destination mount and is marked | |
1838 | * as shared. The cloned mount is added to the peer group of the source | |
1839 | * mount. | |
5afe0022 RP |
1840 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1841 | * of the destination mount and the cloned mount is made slave | |
1842 | * of the same master as that of the source mount. The cloned mount | |
1843 | * is marked as 'shared and slave'. | |
1844 | * (*) the cloned mount is made a slave of the same master as that of the | |
1845 | * source mount. | |
1846 | * | |
9676f0c6 RP |
1847 | * --------------------------------------------------------------------------- |
1848 | * | MOVE MOUNT OPERATION | | |
1849 | * |************************************************************************** | |
1850 | * | source-->| shared | private | slave | unbindable | | |
1851 | * | dest | | | | | | |
1852 | * | | | | | | | | |
1853 | * | v | | | | | | |
1854 | * |************************************************************************** | |
1855 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1856 | * | | | | | | | |
1857 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1858 | * *************************************************************************** | |
5afe0022 RP |
1859 | * |
1860 | * (+) the mount is moved to the destination. And is then propagated to | |
1861 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1862 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1863 | * (+++) the mount is moved to the destination and is then propagated to |
1864 | * all the mounts belonging to the destination mount's propagation tree. | |
1865 | * the mount is marked as 'shared and slave'. | |
1866 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1867 | * |
1868 | * if the source mount is a tree, the operations explained above is | |
1869 | * applied to each mount in the tree. | |
1870 | * Must be called without spinlocks held, since this function can sleep | |
1871 | * in allocations. | |
1872 | */ | |
0fb54e50 | 1873 | static int attach_recursive_mnt(struct mount *source_mnt, |
84d17192 AV |
1874 | struct mount *dest_mnt, |
1875 | struct mountpoint *dest_mp, | |
1876 | struct path *parent_path) | |
b90fa9ae | 1877 | { |
38129a13 | 1878 | HLIST_HEAD(tree_list); |
315fc83e | 1879 | struct mount *child, *p; |
38129a13 | 1880 | struct hlist_node *n; |
719f5d7f | 1881 | int err; |
b90fa9ae | 1882 | |
fc7be130 | 1883 | if (IS_MNT_SHARED(dest_mnt)) { |
0fb54e50 | 1884 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
1885 | if (err) |
1886 | goto out; | |
0b1b901b | 1887 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
f2ebb3a9 | 1888 | lock_mount_hash(); |
0b1b901b AV |
1889 | if (err) |
1890 | goto out_cleanup_ids; | |
909b0a88 | 1891 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
0f0afb1d | 1892 | set_mnt_shared(p); |
0b1b901b AV |
1893 | } else { |
1894 | lock_mount_hash(); | |
b90fa9ae | 1895 | } |
1a390689 | 1896 | if (parent_path) { |
0fb54e50 | 1897 | detach_mnt(source_mnt, parent_path); |
84d17192 | 1898 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
143c8c91 | 1899 | touch_mnt_namespace(source_mnt->mnt_ns); |
21444403 | 1900 | } else { |
84d17192 | 1901 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
1d6a32ac | 1902 | commit_tree(source_mnt, NULL); |
21444403 | 1903 | } |
b90fa9ae | 1904 | |
38129a13 | 1905 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
1d6a32ac | 1906 | struct mount *q; |
38129a13 | 1907 | hlist_del_init(&child->mnt_hash); |
1d6a32ac AV |
1908 | q = __lookup_mnt_last(&child->mnt_parent->mnt, |
1909 | child->mnt_mountpoint); | |
1910 | commit_tree(child, q); | |
b90fa9ae | 1911 | } |
719ea2fb | 1912 | unlock_mount_hash(); |
99b7db7b | 1913 | |
b90fa9ae | 1914 | return 0; |
719f5d7f MS |
1915 | |
1916 | out_cleanup_ids: | |
f2ebb3a9 AV |
1917 | while (!hlist_empty(&tree_list)) { |
1918 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); | |
e819f152 | 1919 | umount_tree(child, UMOUNT_SYNC); |
f2ebb3a9 AV |
1920 | } |
1921 | unlock_mount_hash(); | |
0b1b901b | 1922 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f MS |
1923 | out: |
1924 | return err; | |
b90fa9ae RP |
1925 | } |
1926 | ||
84d17192 | 1927 | static struct mountpoint *lock_mount(struct path *path) |
b12cea91 AV |
1928 | { |
1929 | struct vfsmount *mnt; | |
84d17192 | 1930 | struct dentry *dentry = path->dentry; |
b12cea91 | 1931 | retry: |
84d17192 AV |
1932 | mutex_lock(&dentry->d_inode->i_mutex); |
1933 | if (unlikely(cant_mount(dentry))) { | |
1934 | mutex_unlock(&dentry->d_inode->i_mutex); | |
1935 | return ERR_PTR(-ENOENT); | |
b12cea91 | 1936 | } |
97216be0 | 1937 | namespace_lock(); |
b12cea91 | 1938 | mnt = lookup_mnt(path); |
84d17192 | 1939 | if (likely(!mnt)) { |
e2dfa935 EB |
1940 | struct mountpoint *mp = lookup_mountpoint(dentry); |
1941 | if (!mp) | |
1942 | mp = new_mountpoint(dentry); | |
84d17192 | 1943 | if (IS_ERR(mp)) { |
97216be0 | 1944 | namespace_unlock(); |
84d17192 AV |
1945 | mutex_unlock(&dentry->d_inode->i_mutex); |
1946 | return mp; | |
1947 | } | |
1948 | return mp; | |
1949 | } | |
97216be0 | 1950 | namespace_unlock(); |
b12cea91 AV |
1951 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1952 | path_put(path); | |
1953 | path->mnt = mnt; | |
84d17192 | 1954 | dentry = path->dentry = dget(mnt->mnt_root); |
b12cea91 AV |
1955 | goto retry; |
1956 | } | |
1957 | ||
84d17192 | 1958 | static void unlock_mount(struct mountpoint *where) |
b12cea91 | 1959 | { |
84d17192 AV |
1960 | struct dentry *dentry = where->m_dentry; |
1961 | put_mountpoint(where); | |
328e6d90 | 1962 | namespace_unlock(); |
84d17192 | 1963 | mutex_unlock(&dentry->d_inode->i_mutex); |
b12cea91 AV |
1964 | } |
1965 | ||
84d17192 | 1966 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
1da177e4 | 1967 | { |
95bc5f25 | 1968 | if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER) |
1da177e4 LT |
1969 | return -EINVAL; |
1970 | ||
e36cb0b8 DH |
1971 | if (d_is_dir(mp->m_dentry) != |
1972 | d_is_dir(mnt->mnt.mnt_root)) | |
1da177e4 LT |
1973 | return -ENOTDIR; |
1974 | ||
84d17192 | 1975 | return attach_recursive_mnt(mnt, p, mp, NULL); |
1da177e4 LT |
1976 | } |
1977 | ||
7a2e8a8f VA |
1978 | /* |
1979 | * Sanity check the flags to change_mnt_propagation. | |
1980 | */ | |
1981 | ||
1982 | static int flags_to_propagation_type(int flags) | |
1983 | { | |
7c6e984d | 1984 | int type = flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
1985 | |
1986 | /* Fail if any non-propagation flags are set */ | |
1987 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
1988 | return 0; | |
1989 | /* Only one propagation flag should be set */ | |
1990 | if (!is_power_of_2(type)) | |
1991 | return 0; | |
1992 | return type; | |
1993 | } | |
1994 | ||
07b20889 RP |
1995 | /* |
1996 | * recursively change the type of the mountpoint. | |
1997 | */ | |
0a0d8a46 | 1998 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1999 | { |
315fc83e | 2000 | struct mount *m; |
4b8b21f4 | 2001 | struct mount *mnt = real_mount(path->mnt); |
07b20889 | 2002 | int recurse = flag & MS_REC; |
7a2e8a8f | 2003 | int type; |
719f5d7f | 2004 | int err = 0; |
07b20889 | 2005 | |
2d92ab3c | 2006 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
2007 | return -EINVAL; |
2008 | ||
7a2e8a8f VA |
2009 | type = flags_to_propagation_type(flag); |
2010 | if (!type) | |
2011 | return -EINVAL; | |
2012 | ||
97216be0 | 2013 | namespace_lock(); |
719f5d7f MS |
2014 | if (type == MS_SHARED) { |
2015 | err = invent_group_ids(mnt, recurse); | |
2016 | if (err) | |
2017 | goto out_unlock; | |
2018 | } | |
2019 | ||
719ea2fb | 2020 | lock_mount_hash(); |
909b0a88 | 2021 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
0f0afb1d | 2022 | change_mnt_propagation(m, type); |
719ea2fb | 2023 | unlock_mount_hash(); |
719f5d7f MS |
2024 | |
2025 | out_unlock: | |
97216be0 | 2026 | namespace_unlock(); |
719f5d7f | 2027 | return err; |
07b20889 RP |
2028 | } |
2029 | ||
5ff9d8a6 EB |
2030 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
2031 | { | |
2032 | struct mount *child; | |
2033 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
2034 | if (!is_subdir(child->mnt_mountpoint, dentry)) | |
2035 | continue; | |
2036 | ||
2037 | if (child->mnt.mnt_flags & MNT_LOCKED) | |
2038 | return true; | |
2039 | } | |
2040 | return false; | |
2041 | } | |
2042 | ||
1da177e4 LT |
2043 | /* |
2044 | * do loopback mount. | |
2045 | */ | |
808d4e3c | 2046 | static int do_loopback(struct path *path, const char *old_name, |
2dafe1c4 | 2047 | int recurse) |
1da177e4 | 2048 | { |
2d92ab3c | 2049 | struct path old_path; |
84d17192 AV |
2050 | struct mount *mnt = NULL, *old, *parent; |
2051 | struct mountpoint *mp; | |
57eccb83 | 2052 | int err; |
1da177e4 LT |
2053 | if (!old_name || !*old_name) |
2054 | return -EINVAL; | |
815d405c | 2055 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
2056 | if (err) |
2057 | return err; | |
2058 | ||
8823c079 | 2059 | err = -EINVAL; |
4ce5d2b1 | 2060 | if (mnt_ns_loop(old_path.dentry)) |
8823c079 EB |
2061 | goto out; |
2062 | ||
84d17192 AV |
2063 | mp = lock_mount(path); |
2064 | err = PTR_ERR(mp); | |
2065 | if (IS_ERR(mp)) | |
b12cea91 AV |
2066 | goto out; |
2067 | ||
87129cc0 | 2068 | old = real_mount(old_path.mnt); |
84d17192 | 2069 | parent = real_mount(path->mnt); |
87129cc0 | 2070 | |
1da177e4 | 2071 | err = -EINVAL; |
fc7be130 | 2072 | if (IS_MNT_UNBINDABLE(old)) |
b12cea91 | 2073 | goto out2; |
9676f0c6 | 2074 | |
e149ed2b AV |
2075 | if (!check_mnt(parent)) |
2076 | goto out2; | |
2077 | ||
2078 | if (!check_mnt(old) && old_path.dentry->d_op != &ns_dentry_operations) | |
b12cea91 | 2079 | goto out2; |
1da177e4 | 2080 | |
5ff9d8a6 EB |
2081 | if (!recurse && has_locked_children(old, old_path.dentry)) |
2082 | goto out2; | |
2083 | ||
ccd48bc7 | 2084 | if (recurse) |
4ce5d2b1 | 2085 | mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE); |
ccd48bc7 | 2086 | else |
87129cc0 | 2087 | mnt = clone_mnt(old, old_path.dentry, 0); |
ccd48bc7 | 2088 | |
be34d1a3 DH |
2089 | if (IS_ERR(mnt)) { |
2090 | err = PTR_ERR(mnt); | |
e9c5d8a5 | 2091 | goto out2; |
be34d1a3 | 2092 | } |
ccd48bc7 | 2093 | |
5ff9d8a6 EB |
2094 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
2095 | ||
84d17192 | 2096 | err = graft_tree(mnt, parent, mp); |
ccd48bc7 | 2097 | if (err) { |
719ea2fb | 2098 | lock_mount_hash(); |
e819f152 | 2099 | umount_tree(mnt, UMOUNT_SYNC); |
719ea2fb | 2100 | unlock_mount_hash(); |
5b83d2c5 | 2101 | } |
b12cea91 | 2102 | out2: |
84d17192 | 2103 | unlock_mount(mp); |
ccd48bc7 | 2104 | out: |
2d92ab3c | 2105 | path_put(&old_path); |
1da177e4 LT |
2106 | return err; |
2107 | } | |
2108 | ||
2e4b7fcd DH |
2109 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
2110 | { | |
2111 | int error = 0; | |
2112 | int readonly_request = 0; | |
2113 | ||
2114 | if (ms_flags & MS_RDONLY) | |
2115 | readonly_request = 1; | |
2116 | if (readonly_request == __mnt_is_readonly(mnt)) | |
2117 | return 0; | |
2118 | ||
2119 | if (readonly_request) | |
83adc753 | 2120 | error = mnt_make_readonly(real_mount(mnt)); |
2e4b7fcd | 2121 | else |
83adc753 | 2122 | __mnt_unmake_readonly(real_mount(mnt)); |
2e4b7fcd DH |
2123 | return error; |
2124 | } | |
2125 | ||
1da177e4 LT |
2126 | /* |
2127 | * change filesystem flags. dir should be a physical root of filesystem. | |
2128 | * If you've mounted a non-root directory somewhere and want to do remount | |
2129 | * on it - tough luck. | |
2130 | */ | |
0a0d8a46 | 2131 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
2132 | void *data) |
2133 | { | |
2134 | int err; | |
2d92ab3c | 2135 | struct super_block *sb = path->mnt->mnt_sb; |
143c8c91 | 2136 | struct mount *mnt = real_mount(path->mnt); |
1da177e4 | 2137 | |
143c8c91 | 2138 | if (!check_mnt(mnt)) |
1da177e4 LT |
2139 | return -EINVAL; |
2140 | ||
2d92ab3c | 2141 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
2142 | return -EINVAL; |
2143 | ||
07b64558 EB |
2144 | /* Don't allow changing of locked mnt flags. |
2145 | * | |
2146 | * No locks need to be held here while testing the various | |
2147 | * MNT_LOCK flags because those flags can never be cleared | |
2148 | * once they are set. | |
2149 | */ | |
2150 | if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && | |
2151 | !(mnt_flags & MNT_READONLY)) { | |
2152 | return -EPERM; | |
2153 | } | |
9566d674 EB |
2154 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && |
2155 | !(mnt_flags & MNT_NODEV)) { | |
3e186641 EB |
2156 | /* Was the nodev implicitly added in mount? */ |
2157 | if ((mnt->mnt_ns->user_ns != &init_user_ns) && | |
2158 | !(sb->s_type->fs_flags & FS_USERNS_DEV_MOUNT)) { | |
2159 | mnt_flags |= MNT_NODEV; | |
2160 | } else { | |
2161 | return -EPERM; | |
2162 | } | |
9566d674 EB |
2163 | } |
2164 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && | |
2165 | !(mnt_flags & MNT_NOSUID)) { | |
2166 | return -EPERM; | |
2167 | } | |
2168 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) && | |
2169 | !(mnt_flags & MNT_NOEXEC)) { | |
2170 | return -EPERM; | |
2171 | } | |
2172 | if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && | |
2173 | ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) { | |
2174 | return -EPERM; | |
2175 | } | |
2176 | ||
ff36fe2c EP |
2177 | err = security_sb_remount(sb, data); |
2178 | if (err) | |
2179 | return err; | |
2180 | ||
1da177e4 | 2181 | down_write(&sb->s_umount); |
2e4b7fcd | 2182 | if (flags & MS_BIND) |
2d92ab3c | 2183 | err = change_mount_flags(path->mnt, flags); |
57eccb83 AV |
2184 | else if (!capable(CAP_SYS_ADMIN)) |
2185 | err = -EPERM; | |
4aa98cf7 | 2186 | else |
2e4b7fcd | 2187 | err = do_remount_sb(sb, flags, data, 0); |
7b43a79f | 2188 | if (!err) { |
719ea2fb | 2189 | lock_mount_hash(); |
a6138db8 | 2190 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
143c8c91 | 2191 | mnt->mnt.mnt_flags = mnt_flags; |
143c8c91 | 2192 | touch_mnt_namespace(mnt->mnt_ns); |
719ea2fb | 2193 | unlock_mount_hash(); |
0e55a7cc | 2194 | } |
6339dab8 | 2195 | up_write(&sb->s_umount); |
1da177e4 LT |
2196 | return err; |
2197 | } | |
2198 | ||
cbbe362c | 2199 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 2200 | { |
315fc83e | 2201 | struct mount *p; |
909b0a88 | 2202 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
fc7be130 | 2203 | if (IS_MNT_UNBINDABLE(p)) |
9676f0c6 RP |
2204 | return 1; |
2205 | } | |
2206 | return 0; | |
2207 | } | |
2208 | ||
808d4e3c | 2209 | static int do_move_mount(struct path *path, const char *old_name) |
1da177e4 | 2210 | { |
2d92ab3c | 2211 | struct path old_path, parent_path; |
676da58d | 2212 | struct mount *p; |
0fb54e50 | 2213 | struct mount *old; |
84d17192 | 2214 | struct mountpoint *mp; |
57eccb83 | 2215 | int err; |
1da177e4 LT |
2216 | if (!old_name || !*old_name) |
2217 | return -EINVAL; | |
2d92ab3c | 2218 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
2219 | if (err) |
2220 | return err; | |
2221 | ||
84d17192 AV |
2222 | mp = lock_mount(path); |
2223 | err = PTR_ERR(mp); | |
2224 | if (IS_ERR(mp)) | |
cc53ce53 DH |
2225 | goto out; |
2226 | ||
143c8c91 | 2227 | old = real_mount(old_path.mnt); |
fc7be130 | 2228 | p = real_mount(path->mnt); |
143c8c91 | 2229 | |
1da177e4 | 2230 | err = -EINVAL; |
fc7be130 | 2231 | if (!check_mnt(p) || !check_mnt(old)) |
1da177e4 LT |
2232 | goto out1; |
2233 | ||
5ff9d8a6 EB |
2234 | if (old->mnt.mnt_flags & MNT_LOCKED) |
2235 | goto out1; | |
2236 | ||
1da177e4 | 2237 | err = -EINVAL; |
2d92ab3c | 2238 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 2239 | goto out1; |
1da177e4 | 2240 | |
676da58d | 2241 | if (!mnt_has_parent(old)) |
21444403 | 2242 | goto out1; |
1da177e4 | 2243 | |
e36cb0b8 DH |
2244 | if (d_is_dir(path->dentry) != |
2245 | d_is_dir(old_path.dentry)) | |
21444403 RP |
2246 | goto out1; |
2247 | /* | |
2248 | * Don't move a mount residing in a shared parent. | |
2249 | */ | |
fc7be130 | 2250 | if (IS_MNT_SHARED(old->mnt_parent)) |
21444403 | 2251 | goto out1; |
9676f0c6 RP |
2252 | /* |
2253 | * Don't move a mount tree containing unbindable mounts to a destination | |
2254 | * mount which is shared. | |
2255 | */ | |
fc7be130 | 2256 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
9676f0c6 | 2257 | goto out1; |
1da177e4 | 2258 | err = -ELOOP; |
fc7be130 | 2259 | for (; mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 2260 | if (p == old) |
21444403 | 2261 | goto out1; |
1da177e4 | 2262 | |
84d17192 | 2263 | err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path); |
4ac91378 | 2264 | if (err) |
21444403 | 2265 | goto out1; |
1da177e4 LT |
2266 | |
2267 | /* if the mount is moved, it should no longer be expire | |
2268 | * automatically */ | |
6776db3d | 2269 | list_del_init(&old->mnt_expire); |
1da177e4 | 2270 | out1: |
84d17192 | 2271 | unlock_mount(mp); |
1da177e4 | 2272 | out: |
1da177e4 | 2273 | if (!err) |
1a390689 | 2274 | path_put(&parent_path); |
2d92ab3c | 2275 | path_put(&old_path); |
1da177e4 LT |
2276 | return err; |
2277 | } | |
2278 | ||
9d412a43 AV |
2279 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
2280 | { | |
2281 | int err; | |
2282 | const char *subtype = strchr(fstype, '.'); | |
2283 | if (subtype) { | |
2284 | subtype++; | |
2285 | err = -EINVAL; | |
2286 | if (!subtype[0]) | |
2287 | goto err; | |
2288 | } else | |
2289 | subtype = ""; | |
2290 | ||
2291 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); | |
2292 | err = -ENOMEM; | |
2293 | if (!mnt->mnt_sb->s_subtype) | |
2294 | goto err; | |
2295 | return mnt; | |
2296 | ||
2297 | err: | |
2298 | mntput(mnt); | |
2299 | return ERR_PTR(err); | |
2300 | } | |
2301 | ||
9d412a43 AV |
2302 | /* |
2303 | * add a mount into a namespace's mount tree | |
2304 | */ | |
95bc5f25 | 2305 | static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) |
9d412a43 | 2306 | { |
84d17192 AV |
2307 | struct mountpoint *mp; |
2308 | struct mount *parent; | |
9d412a43 AV |
2309 | int err; |
2310 | ||
f2ebb3a9 | 2311 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
9d412a43 | 2312 | |
84d17192 AV |
2313 | mp = lock_mount(path); |
2314 | if (IS_ERR(mp)) | |
2315 | return PTR_ERR(mp); | |
9d412a43 | 2316 | |
84d17192 | 2317 | parent = real_mount(path->mnt); |
9d412a43 | 2318 | err = -EINVAL; |
84d17192 | 2319 | if (unlikely(!check_mnt(parent))) { |
156cacb1 AV |
2320 | /* that's acceptable only for automounts done in private ns */ |
2321 | if (!(mnt_flags & MNT_SHRINKABLE)) | |
2322 | goto unlock; | |
2323 | /* ... and for those we'd better have mountpoint still alive */ | |
84d17192 | 2324 | if (!parent->mnt_ns) |
156cacb1 AV |
2325 | goto unlock; |
2326 | } | |
9d412a43 AV |
2327 | |
2328 | /* Refuse the same filesystem on the same mount point */ | |
2329 | err = -EBUSY; | |
95bc5f25 | 2330 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 AV |
2331 | path->mnt->mnt_root == path->dentry) |
2332 | goto unlock; | |
2333 | ||
2334 | err = -EINVAL; | |
e36cb0b8 | 2335 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
9d412a43 AV |
2336 | goto unlock; |
2337 | ||
95bc5f25 | 2338 | newmnt->mnt.mnt_flags = mnt_flags; |
84d17192 | 2339 | err = graft_tree(newmnt, parent, mp); |
9d412a43 AV |
2340 | |
2341 | unlock: | |
84d17192 | 2342 | unlock_mount(mp); |
9d412a43 AV |
2343 | return err; |
2344 | } | |
b1e75df4 | 2345 | |
8c6cf9cc | 2346 | static bool fs_fully_visible(struct file_system_type *fs_type, int *new_mnt_flags); |
1b852bce | 2347 | |
1da177e4 LT |
2348 | /* |
2349 | * create a new mount for userspace and request it to be added into the | |
2350 | * namespace's tree | |
2351 | */ | |
0c55cfc4 | 2352 | static int do_new_mount(struct path *path, const char *fstype, int flags, |
808d4e3c | 2353 | int mnt_flags, const char *name, void *data) |
1da177e4 | 2354 | { |
0c55cfc4 | 2355 | struct file_system_type *type; |
9b40bc90 | 2356 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
1da177e4 | 2357 | struct vfsmount *mnt; |
15f9a3f3 | 2358 | int err; |
1da177e4 | 2359 | |
0c55cfc4 | 2360 | if (!fstype) |
1da177e4 LT |
2361 | return -EINVAL; |
2362 | ||
0c55cfc4 EB |
2363 | type = get_fs_type(fstype); |
2364 | if (!type) | |
2365 | return -ENODEV; | |
2366 | ||
2367 | if (user_ns != &init_user_ns) { | |
2368 | if (!(type->fs_flags & FS_USERNS_MOUNT)) { | |
2369 | put_filesystem(type); | |
2370 | return -EPERM; | |
2371 | } | |
2372 | /* Only in special cases allow devices from mounts | |
2373 | * created outside the initial user namespace. | |
2374 | */ | |
2375 | if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { | |
2376 | flags |= MS_NODEV; | |
9566d674 | 2377 | mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; |
0c55cfc4 | 2378 | } |
1b852bce | 2379 | if (type->fs_flags & FS_USERNS_VISIBLE) { |
8c6cf9cc | 2380 | if (!fs_fully_visible(type, &mnt_flags)) |
1b852bce EB |
2381 | return -EPERM; |
2382 | } | |
0c55cfc4 EB |
2383 | } |
2384 | ||
2385 | mnt = vfs_kern_mount(type, flags, name, data); | |
2386 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && | |
2387 | !mnt->mnt_sb->s_subtype) | |
2388 | mnt = fs_set_subtype(mnt, fstype); | |
2389 | ||
2390 | put_filesystem(type); | |
1da177e4 LT |
2391 | if (IS_ERR(mnt)) |
2392 | return PTR_ERR(mnt); | |
2393 | ||
95bc5f25 | 2394 | err = do_add_mount(real_mount(mnt), path, mnt_flags); |
15f9a3f3 AV |
2395 | if (err) |
2396 | mntput(mnt); | |
2397 | return err; | |
1da177e4 LT |
2398 | } |
2399 | ||
19a167af AV |
2400 | int finish_automount(struct vfsmount *m, struct path *path) |
2401 | { | |
6776db3d | 2402 | struct mount *mnt = real_mount(m); |
19a167af AV |
2403 | int err; |
2404 | /* The new mount record should have at least 2 refs to prevent it being | |
2405 | * expired before we get a chance to add it | |
2406 | */ | |
6776db3d | 2407 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
2408 | |
2409 | if (m->mnt_sb == path->mnt->mnt_sb && | |
2410 | m->mnt_root == path->dentry) { | |
b1e75df4 AV |
2411 | err = -ELOOP; |
2412 | goto fail; | |
19a167af AV |
2413 | } |
2414 | ||
95bc5f25 | 2415 | err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
b1e75df4 AV |
2416 | if (!err) |
2417 | return 0; | |
2418 | fail: | |
2419 | /* remove m from any expiration list it may be on */ | |
6776db3d | 2420 | if (!list_empty(&mnt->mnt_expire)) { |
97216be0 | 2421 | namespace_lock(); |
6776db3d | 2422 | list_del_init(&mnt->mnt_expire); |
97216be0 | 2423 | namespace_unlock(); |
19a167af | 2424 | } |
b1e75df4 AV |
2425 | mntput(m); |
2426 | mntput(m); | |
19a167af AV |
2427 | return err; |
2428 | } | |
2429 | ||
ea5b778a DH |
2430 | /** |
2431 | * mnt_set_expiry - Put a mount on an expiration list | |
2432 | * @mnt: The mount to list. | |
2433 | * @expiry_list: The list to add the mount to. | |
2434 | */ | |
2435 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
2436 | { | |
97216be0 | 2437 | namespace_lock(); |
ea5b778a | 2438 | |
6776db3d | 2439 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a | 2440 | |
97216be0 | 2441 | namespace_unlock(); |
ea5b778a DH |
2442 | } |
2443 | EXPORT_SYMBOL(mnt_set_expiry); | |
2444 | ||
1da177e4 LT |
2445 | /* |
2446 | * process a list of expirable mountpoints with the intent of discarding any | |
2447 | * mountpoints that aren't in use and haven't been touched since last we came | |
2448 | * here | |
2449 | */ | |
2450 | void mark_mounts_for_expiry(struct list_head *mounts) | |
2451 | { | |
761d5c38 | 2452 | struct mount *mnt, *next; |
1da177e4 LT |
2453 | LIST_HEAD(graveyard); |
2454 | ||
2455 | if (list_empty(mounts)) | |
2456 | return; | |
2457 | ||
97216be0 | 2458 | namespace_lock(); |
719ea2fb | 2459 | lock_mount_hash(); |
1da177e4 LT |
2460 | |
2461 | /* extract from the expiration list every vfsmount that matches the | |
2462 | * following criteria: | |
2463 | * - only referenced by its parent vfsmount | |
2464 | * - still marked for expiry (marked on the last call here; marks are | |
2465 | * cleared by mntput()) | |
2466 | */ | |
6776db3d | 2467 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
863d684f | 2468 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1ab59738 | 2469 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 2470 | continue; |
6776db3d | 2471 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 2472 | } |
bcc5c7d2 | 2473 | while (!list_empty(&graveyard)) { |
6776db3d | 2474 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
143c8c91 | 2475 | touch_mnt_namespace(mnt->mnt_ns); |
e819f152 | 2476 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 | 2477 | } |
719ea2fb | 2478 | unlock_mount_hash(); |
3ab6abee | 2479 | namespace_unlock(); |
5528f911 TM |
2480 | } |
2481 | ||
2482 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
2483 | ||
2484 | /* | |
2485 | * Ripoff of 'select_parent()' | |
2486 | * | |
2487 | * search the list of submounts for a given mountpoint, and move any | |
2488 | * shrinkable submounts to the 'graveyard' list. | |
2489 | */ | |
692afc31 | 2490 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 2491 | { |
692afc31 | 2492 | struct mount *this_parent = parent; |
5528f911 TM |
2493 | struct list_head *next; |
2494 | int found = 0; | |
2495 | ||
2496 | repeat: | |
6b41d536 | 2497 | next = this_parent->mnt_mounts.next; |
5528f911 | 2498 | resume: |
6b41d536 | 2499 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 2500 | struct list_head *tmp = next; |
6b41d536 | 2501 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
2502 | |
2503 | next = tmp->next; | |
692afc31 | 2504 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 2505 | continue; |
5528f911 TM |
2506 | /* |
2507 | * Descend a level if the d_mounts list is non-empty. | |
2508 | */ | |
6b41d536 | 2509 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
2510 | this_parent = mnt; |
2511 | goto repeat; | |
2512 | } | |
1da177e4 | 2513 | |
1ab59738 | 2514 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 2515 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
2516 | found++; |
2517 | } | |
1da177e4 | 2518 | } |
5528f911 TM |
2519 | /* |
2520 | * All done at this level ... ascend and resume the search | |
2521 | */ | |
2522 | if (this_parent != parent) { | |
6b41d536 | 2523 | next = this_parent->mnt_child.next; |
0714a533 | 2524 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
2525 | goto resume; |
2526 | } | |
2527 | return found; | |
2528 | } | |
2529 | ||
2530 | /* | |
2531 | * process a list of expirable mountpoints with the intent of discarding any | |
2532 | * submounts of a specific parent mountpoint | |
99b7db7b | 2533 | * |
48a066e7 | 2534 | * mount_lock must be held for write |
5528f911 | 2535 | */ |
b54b9be7 | 2536 | static void shrink_submounts(struct mount *mnt) |
5528f911 TM |
2537 | { |
2538 | LIST_HEAD(graveyard); | |
761d5c38 | 2539 | struct mount *m; |
5528f911 | 2540 | |
5528f911 | 2541 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 2542 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 2543 | while (!list_empty(&graveyard)) { |
761d5c38 | 2544 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 2545 | mnt_expire); |
143c8c91 | 2546 | touch_mnt_namespace(m->mnt_ns); |
e819f152 | 2547 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 AV |
2548 | } |
2549 | } | |
1da177e4 LT |
2550 | } |
2551 | ||
1da177e4 LT |
2552 | /* |
2553 | * Some copy_from_user() implementations do not return the exact number of | |
2554 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
2555 | * Note that this function differs from copy_from_user() in that it will oops | |
2556 | * on bad values of `to', rather than returning a short copy. | |
2557 | */ | |
b58fed8b RP |
2558 | static long exact_copy_from_user(void *to, const void __user * from, |
2559 | unsigned long n) | |
1da177e4 LT |
2560 | { |
2561 | char *t = to; | |
2562 | const char __user *f = from; | |
2563 | char c; | |
2564 | ||
2565 | if (!access_ok(VERIFY_READ, from, n)) | |
2566 | return n; | |
2567 | ||
2568 | while (n) { | |
2569 | if (__get_user(c, f)) { | |
2570 | memset(t, 0, n); | |
2571 | break; | |
2572 | } | |
2573 | *t++ = c; | |
2574 | f++; | |
2575 | n--; | |
2576 | } | |
2577 | return n; | |
2578 | } | |
2579 | ||
b58fed8b | 2580 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
2581 | { |
2582 | int i; | |
2583 | unsigned long page; | |
2584 | unsigned long size; | |
b58fed8b | 2585 | |
1da177e4 LT |
2586 | *where = 0; |
2587 | if (!data) | |
2588 | return 0; | |
2589 | ||
2590 | if (!(page = __get_free_page(GFP_KERNEL))) | |
2591 | return -ENOMEM; | |
2592 | ||
2593 | /* We only care that *some* data at the address the user | |
2594 | * gave us is valid. Just in case, we'll zero | |
2595 | * the remainder of the page. | |
2596 | */ | |
2597 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
2598 | size = TASK_SIZE - (unsigned long)data; | |
2599 | if (size > PAGE_SIZE) | |
2600 | size = PAGE_SIZE; | |
2601 | ||
2602 | i = size - exact_copy_from_user((void *)page, data, size); | |
2603 | if (!i) { | |
b58fed8b | 2604 | free_page(page); |
1da177e4 LT |
2605 | return -EFAULT; |
2606 | } | |
2607 | if (i != PAGE_SIZE) | |
2608 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
2609 | *where = page; | |
2610 | return 0; | |
2611 | } | |
2612 | ||
b8850d1f | 2613 | char *copy_mount_string(const void __user *data) |
eca6f534 | 2614 | { |
b8850d1f | 2615 | return data ? strndup_user(data, PAGE_SIZE) : NULL; |
eca6f534 VN |
2616 | } |
2617 | ||
1da177e4 LT |
2618 | /* |
2619 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
2620 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
2621 | * | |
2622 | * data is a (void *) that can point to any structure up to | |
2623 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
2624 | * information (or be NULL). | |
2625 | * | |
2626 | * Pre-0.97 versions of mount() didn't have a flags word. | |
2627 | * When the flags word was introduced its top half was required | |
2628 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
2629 | * Therefore, if this magic number is present, it carries no information | |
2630 | * and must be discarded. | |
2631 | */ | |
5e6123f3 | 2632 | long do_mount(const char *dev_name, const char __user *dir_name, |
808d4e3c | 2633 | const char *type_page, unsigned long flags, void *data_page) |
1da177e4 | 2634 | { |
2d92ab3c | 2635 | struct path path; |
1da177e4 LT |
2636 | int retval = 0; |
2637 | int mnt_flags = 0; | |
2638 | ||
2639 | /* Discard magic */ | |
2640 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
2641 | flags &= ~MS_MGC_MSK; | |
2642 | ||
2643 | /* Basic sanity checks */ | |
1da177e4 LT |
2644 | if (data_page) |
2645 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
2646 | ||
a27ab9f2 | 2647 | /* ... and get the mountpoint */ |
5e6123f3 | 2648 | retval = user_path(dir_name, &path); |
a27ab9f2 TH |
2649 | if (retval) |
2650 | return retval; | |
2651 | ||
2652 | retval = security_sb_mount(dev_name, &path, | |
2653 | type_page, flags, data_page); | |
0d5cadb8 AV |
2654 | if (!retval && !may_mount()) |
2655 | retval = -EPERM; | |
a27ab9f2 TH |
2656 | if (retval) |
2657 | goto dput_out; | |
2658 | ||
613cbe3d AK |
2659 | /* Default to relatime unless overriden */ |
2660 | if (!(flags & MS_NOATIME)) | |
2661 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 2662 | |
1da177e4 LT |
2663 | /* Separate the per-mountpoint flags */ |
2664 | if (flags & MS_NOSUID) | |
2665 | mnt_flags |= MNT_NOSUID; | |
2666 | if (flags & MS_NODEV) | |
2667 | mnt_flags |= MNT_NODEV; | |
2668 | if (flags & MS_NOEXEC) | |
2669 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
2670 | if (flags & MS_NOATIME) |
2671 | mnt_flags |= MNT_NOATIME; | |
2672 | if (flags & MS_NODIRATIME) | |
2673 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
2674 | if (flags & MS_STRICTATIME) |
2675 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
2676 | if (flags & MS_RDONLY) |
2677 | mnt_flags |= MNT_READONLY; | |
fc33a7bb | 2678 | |
ffbc6f0e EB |
2679 | /* The default atime for remount is preservation */ |
2680 | if ((flags & MS_REMOUNT) && | |
2681 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | | |
2682 | MS_STRICTATIME)) == 0)) { | |
2683 | mnt_flags &= ~MNT_ATIME_MASK; | |
2684 | mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; | |
2685 | } | |
2686 | ||
7a4dec53 | 2687 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
d0adde57 MG |
2688 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
2689 | MS_STRICTATIME); | |
1da177e4 | 2690 | |
1da177e4 | 2691 | if (flags & MS_REMOUNT) |
2d92ab3c | 2692 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
2693 | data_page); |
2694 | else if (flags & MS_BIND) | |
2d92ab3c | 2695 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 2696 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 2697 | retval = do_change_type(&path, flags); |
1da177e4 | 2698 | else if (flags & MS_MOVE) |
2d92ab3c | 2699 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 2700 | else |
2d92ab3c | 2701 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
2702 | dev_name, data_page); |
2703 | dput_out: | |
2d92ab3c | 2704 | path_put(&path); |
1da177e4 LT |
2705 | return retval; |
2706 | } | |
2707 | ||
771b1371 EB |
2708 | static void free_mnt_ns(struct mnt_namespace *ns) |
2709 | { | |
6344c433 | 2710 | ns_free_inum(&ns->ns); |
771b1371 EB |
2711 | put_user_ns(ns->user_ns); |
2712 | kfree(ns); | |
2713 | } | |
2714 | ||
8823c079 EB |
2715 | /* |
2716 | * Assign a sequence number so we can detect when we attempt to bind | |
2717 | * mount a reference to an older mount namespace into the current | |
2718 | * mount namespace, preventing reference counting loops. A 64bit | |
2719 | * number incrementing at 10Ghz will take 12,427 years to wrap which | |
2720 | * is effectively never, so we can ignore the possibility. | |
2721 | */ | |
2722 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); | |
2723 | ||
771b1371 | 2724 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) |
cf8d2c11 TM |
2725 | { |
2726 | struct mnt_namespace *new_ns; | |
98f842e6 | 2727 | int ret; |
cf8d2c11 TM |
2728 | |
2729 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
2730 | if (!new_ns) | |
2731 | return ERR_PTR(-ENOMEM); | |
6344c433 | 2732 | ret = ns_alloc_inum(&new_ns->ns); |
98f842e6 EB |
2733 | if (ret) { |
2734 | kfree(new_ns); | |
2735 | return ERR_PTR(ret); | |
2736 | } | |
33c42940 | 2737 | new_ns->ns.ops = &mntns_operations; |
8823c079 | 2738 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
cf8d2c11 TM |
2739 | atomic_set(&new_ns->count, 1); |
2740 | new_ns->root = NULL; | |
2741 | INIT_LIST_HEAD(&new_ns->list); | |
2742 | init_waitqueue_head(&new_ns->poll); | |
2743 | new_ns->event = 0; | |
771b1371 | 2744 | new_ns->user_ns = get_user_ns(user_ns); |
cf8d2c11 TM |
2745 | return new_ns; |
2746 | } | |
2747 | ||
9559f689 AV |
2748 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
2749 | struct user_namespace *user_ns, struct fs_struct *new_fs) | |
1da177e4 | 2750 | { |
6b3286ed | 2751 | struct mnt_namespace *new_ns; |
7f2da1e7 | 2752 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 2753 | struct mount *p, *q; |
9559f689 | 2754 | struct mount *old; |
cb338d06 | 2755 | struct mount *new; |
7a472ef4 | 2756 | int copy_flags; |
1da177e4 | 2757 | |
9559f689 AV |
2758 | BUG_ON(!ns); |
2759 | ||
2760 | if (likely(!(flags & CLONE_NEWNS))) { | |
2761 | get_mnt_ns(ns); | |
2762 | return ns; | |
2763 | } | |
2764 | ||
2765 | old = ns->root; | |
2766 | ||
771b1371 | 2767 | new_ns = alloc_mnt_ns(user_ns); |
cf8d2c11 TM |
2768 | if (IS_ERR(new_ns)) |
2769 | return new_ns; | |
1da177e4 | 2770 | |
97216be0 | 2771 | namespace_lock(); |
1da177e4 | 2772 | /* First pass: copy the tree topology */ |
4ce5d2b1 | 2773 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
9559f689 | 2774 | if (user_ns != ns->user_ns) |
132c94e3 | 2775 | copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED; |
7a472ef4 | 2776 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
be34d1a3 | 2777 | if (IS_ERR(new)) { |
328e6d90 | 2778 | namespace_unlock(); |
771b1371 | 2779 | free_mnt_ns(new_ns); |
be34d1a3 | 2780 | return ERR_CAST(new); |
1da177e4 | 2781 | } |
be08d6d2 | 2782 | new_ns->root = new; |
1a4eeaf2 | 2783 | list_add_tail(&new_ns->list, &new->mnt_list); |
1da177e4 LT |
2784 | |
2785 | /* | |
2786 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2787 | * as belonging to new namespace. We have already acquired a private | |
2788 | * fs_struct, so tsk->fs->lock is not needed. | |
2789 | */ | |
909b0a88 | 2790 | p = old; |
cb338d06 | 2791 | q = new; |
1da177e4 | 2792 | while (p) { |
143c8c91 | 2793 | q->mnt_ns = new_ns; |
9559f689 AV |
2794 | if (new_fs) { |
2795 | if (&p->mnt == new_fs->root.mnt) { | |
2796 | new_fs->root.mnt = mntget(&q->mnt); | |
315fc83e | 2797 | rootmnt = &p->mnt; |
1da177e4 | 2798 | } |
9559f689 AV |
2799 | if (&p->mnt == new_fs->pwd.mnt) { |
2800 | new_fs->pwd.mnt = mntget(&q->mnt); | |
315fc83e | 2801 | pwdmnt = &p->mnt; |
1da177e4 | 2802 | } |
1da177e4 | 2803 | } |
909b0a88 AV |
2804 | p = next_mnt(p, old); |
2805 | q = next_mnt(q, new); | |
4ce5d2b1 EB |
2806 | if (!q) |
2807 | break; | |
2808 | while (p->mnt.mnt_root != q->mnt.mnt_root) | |
2809 | p = next_mnt(p, old); | |
1da177e4 | 2810 | } |
328e6d90 | 2811 | namespace_unlock(); |
1da177e4 | 2812 | |
1da177e4 | 2813 | if (rootmnt) |
f03c6599 | 2814 | mntput(rootmnt); |
1da177e4 | 2815 | if (pwdmnt) |
f03c6599 | 2816 | mntput(pwdmnt); |
1da177e4 | 2817 | |
741a2951 | 2818 | return new_ns; |
1da177e4 LT |
2819 | } |
2820 | ||
cf8d2c11 TM |
2821 | /** |
2822 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2823 | * @mnt: pointer to the new root filesystem mountpoint | |
2824 | */ | |
1a4eeaf2 | 2825 | static struct mnt_namespace *create_mnt_ns(struct vfsmount *m) |
cf8d2c11 | 2826 | { |
771b1371 | 2827 | struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns); |
cf8d2c11 | 2828 | if (!IS_ERR(new_ns)) { |
1a4eeaf2 AV |
2829 | struct mount *mnt = real_mount(m); |
2830 | mnt->mnt_ns = new_ns; | |
be08d6d2 | 2831 | new_ns->root = mnt; |
b1983cd8 | 2832 | list_add(&mnt->mnt_list, &new_ns->list); |
c1334495 | 2833 | } else { |
1a4eeaf2 | 2834 | mntput(m); |
cf8d2c11 TM |
2835 | } |
2836 | return new_ns; | |
2837 | } | |
cf8d2c11 | 2838 | |
ea441d11 AV |
2839 | struct dentry *mount_subtree(struct vfsmount *mnt, const char *name) |
2840 | { | |
2841 | struct mnt_namespace *ns; | |
d31da0f0 | 2842 | struct super_block *s; |
ea441d11 AV |
2843 | struct path path; |
2844 | int err; | |
2845 | ||
2846 | ns = create_mnt_ns(mnt); | |
2847 | if (IS_ERR(ns)) | |
2848 | return ERR_CAST(ns); | |
2849 | ||
2850 | err = vfs_path_lookup(mnt->mnt_root, mnt, | |
2851 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); | |
2852 | ||
2853 | put_mnt_ns(ns); | |
2854 | ||
2855 | if (err) | |
2856 | return ERR_PTR(err); | |
2857 | ||
2858 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
2859 | s = path.mnt->mnt_sb; |
2860 | atomic_inc(&s->s_active); | |
ea441d11 AV |
2861 | mntput(path.mnt); |
2862 | /* lock the sucker */ | |
d31da0f0 | 2863 | down_write(&s->s_umount); |
ea441d11 AV |
2864 | /* ... and return the root of (sub)tree on it */ |
2865 | return path.dentry; | |
2866 | } | |
2867 | EXPORT_SYMBOL(mount_subtree); | |
2868 | ||
bdc480e3 HC |
2869 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2870 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2871 | { |
eca6f534 VN |
2872 | int ret; |
2873 | char *kernel_type; | |
eca6f534 | 2874 | char *kernel_dev; |
1da177e4 | 2875 | unsigned long data_page; |
1da177e4 | 2876 | |
b8850d1f TG |
2877 | kernel_type = copy_mount_string(type); |
2878 | ret = PTR_ERR(kernel_type); | |
2879 | if (IS_ERR(kernel_type)) | |
eca6f534 | 2880 | goto out_type; |
1da177e4 | 2881 | |
b8850d1f TG |
2882 | kernel_dev = copy_mount_string(dev_name); |
2883 | ret = PTR_ERR(kernel_dev); | |
2884 | if (IS_ERR(kernel_dev)) | |
eca6f534 | 2885 | goto out_dev; |
1da177e4 | 2886 | |
eca6f534 VN |
2887 | ret = copy_mount_options(data, &data_page); |
2888 | if (ret < 0) | |
2889 | goto out_data; | |
1da177e4 | 2890 | |
5e6123f3 | 2891 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, |
eca6f534 | 2892 | (void *) data_page); |
1da177e4 | 2893 | |
eca6f534 VN |
2894 | free_page(data_page); |
2895 | out_data: | |
2896 | kfree(kernel_dev); | |
2897 | out_dev: | |
eca6f534 VN |
2898 | kfree(kernel_type); |
2899 | out_type: | |
2900 | return ret; | |
1da177e4 LT |
2901 | } |
2902 | ||
afac7cba AV |
2903 | /* |
2904 | * Return true if path is reachable from root | |
2905 | * | |
48a066e7 | 2906 | * namespace_sem or mount_lock is held |
afac7cba | 2907 | */ |
643822b4 | 2908 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
2909 | const struct path *root) |
2910 | { | |
643822b4 | 2911 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 2912 | dentry = mnt->mnt_mountpoint; |
0714a533 | 2913 | mnt = mnt->mnt_parent; |
afac7cba | 2914 | } |
643822b4 | 2915 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
2916 | } |
2917 | ||
2918 | int path_is_under(struct path *path1, struct path *path2) | |
2919 | { | |
2920 | int res; | |
48a066e7 | 2921 | read_seqlock_excl(&mount_lock); |
643822b4 | 2922 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
48a066e7 | 2923 | read_sequnlock_excl(&mount_lock); |
afac7cba AV |
2924 | return res; |
2925 | } | |
2926 | EXPORT_SYMBOL(path_is_under); | |
2927 | ||
1da177e4 LT |
2928 | /* |
2929 | * pivot_root Semantics: | |
2930 | * Moves the root file system of the current process to the directory put_old, | |
2931 | * makes new_root as the new root file system of the current process, and sets | |
2932 | * root/cwd of all processes which had them on the current root to new_root. | |
2933 | * | |
2934 | * Restrictions: | |
2935 | * The new_root and put_old must be directories, and must not be on the | |
2936 | * same file system as the current process root. The put_old must be | |
2937 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2938 | * pointed to by put_old must yield the same directory as new_root. No other | |
2939 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2940 | * | |
4a0d11fa NB |
2941 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2942 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2943 | * in this situation. | |
2944 | * | |
1da177e4 LT |
2945 | * Notes: |
2946 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2947 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2948 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2949 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2950 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2951 | * first. | |
2952 | */ | |
3480b257 HC |
2953 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2954 | const char __user *, put_old) | |
1da177e4 | 2955 | { |
2d8f3038 | 2956 | struct path new, old, parent_path, root_parent, root; |
84d17192 AV |
2957 | struct mount *new_mnt, *root_mnt, *old_mnt; |
2958 | struct mountpoint *old_mp, *root_mp; | |
1da177e4 LT |
2959 | int error; |
2960 | ||
9b40bc90 | 2961 | if (!may_mount()) |
1da177e4 LT |
2962 | return -EPERM; |
2963 | ||
2d8f3038 | 2964 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2965 | if (error) |
2966 | goto out0; | |
1da177e4 | 2967 | |
2d8f3038 | 2968 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2969 | if (error) |
2970 | goto out1; | |
2971 | ||
2d8f3038 | 2972 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
2973 | if (error) |
2974 | goto out2; | |
1da177e4 | 2975 | |
f7ad3c6b | 2976 | get_fs_root(current->fs, &root); |
84d17192 AV |
2977 | old_mp = lock_mount(&old); |
2978 | error = PTR_ERR(old_mp); | |
2979 | if (IS_ERR(old_mp)) | |
b12cea91 AV |
2980 | goto out3; |
2981 | ||
1da177e4 | 2982 | error = -EINVAL; |
419148da AV |
2983 | new_mnt = real_mount(new.mnt); |
2984 | root_mnt = real_mount(root.mnt); | |
84d17192 AV |
2985 | old_mnt = real_mount(old.mnt); |
2986 | if (IS_MNT_SHARED(old_mnt) || | |
fc7be130 AV |
2987 | IS_MNT_SHARED(new_mnt->mnt_parent) || |
2988 | IS_MNT_SHARED(root_mnt->mnt_parent)) | |
b12cea91 | 2989 | goto out4; |
143c8c91 | 2990 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
b12cea91 | 2991 | goto out4; |
5ff9d8a6 EB |
2992 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
2993 | goto out4; | |
1da177e4 | 2994 | error = -ENOENT; |
f3da392e | 2995 | if (d_unlinked(new.dentry)) |
b12cea91 | 2996 | goto out4; |
1da177e4 | 2997 | error = -EBUSY; |
84d17192 | 2998 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
b12cea91 | 2999 | goto out4; /* loop, on the same file system */ |
1da177e4 | 3000 | error = -EINVAL; |
8c3ee42e | 3001 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 3002 | goto out4; /* not a mountpoint */ |
676da58d | 3003 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 3004 | goto out4; /* not attached */ |
84d17192 | 3005 | root_mp = root_mnt->mnt_mp; |
2d8f3038 | 3006 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 3007 | goto out4; /* not a mountpoint */ |
676da58d | 3008 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 3009 | goto out4; /* not attached */ |
4ac91378 | 3010 | /* make sure we can reach put_old from new_root */ |
84d17192 | 3011 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
b12cea91 | 3012 | goto out4; |
0d082601 EB |
3013 | /* make certain new is below the root */ |
3014 | if (!is_path_reachable(new_mnt, new.dentry, &root)) | |
3015 | goto out4; | |
84d17192 | 3016 | root_mp->m_count++; /* pin it so it won't go away */ |
719ea2fb | 3017 | lock_mount_hash(); |
419148da AV |
3018 | detach_mnt(new_mnt, &parent_path); |
3019 | detach_mnt(root_mnt, &root_parent); | |
5ff9d8a6 EB |
3020 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
3021 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; | |
3022 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
3023 | } | |
4ac91378 | 3024 | /* mount old root on put_old */ |
84d17192 | 3025 | attach_mnt(root_mnt, old_mnt, old_mp); |
4ac91378 | 3026 | /* mount new_root on / */ |
84d17192 | 3027 | attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp); |
6b3286ed | 3028 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
4fed655c EB |
3029 | /* A moved mount should not expire automatically */ |
3030 | list_del_init(&new_mnt->mnt_expire); | |
719ea2fb | 3031 | unlock_mount_hash(); |
2d8f3038 | 3032 | chroot_fs_refs(&root, &new); |
84d17192 | 3033 | put_mountpoint(root_mp); |
1da177e4 | 3034 | error = 0; |
b12cea91 | 3035 | out4: |
84d17192 | 3036 | unlock_mount(old_mp); |
b12cea91 AV |
3037 | if (!error) { |
3038 | path_put(&root_parent); | |
3039 | path_put(&parent_path); | |
3040 | } | |
3041 | out3: | |
8c3ee42e | 3042 | path_put(&root); |
b12cea91 | 3043 | out2: |
2d8f3038 | 3044 | path_put(&old); |
1da177e4 | 3045 | out1: |
2d8f3038 | 3046 | path_put(&new); |
1da177e4 | 3047 | out0: |
1da177e4 | 3048 | return error; |
1da177e4 LT |
3049 | } |
3050 | ||
3051 | static void __init init_mount_tree(void) | |
3052 | { | |
3053 | struct vfsmount *mnt; | |
6b3286ed | 3054 | struct mnt_namespace *ns; |
ac748a09 | 3055 | struct path root; |
0c55cfc4 | 3056 | struct file_system_type *type; |
1da177e4 | 3057 | |
0c55cfc4 EB |
3058 | type = get_fs_type("rootfs"); |
3059 | if (!type) | |
3060 | panic("Can't find rootfs type"); | |
3061 | mnt = vfs_kern_mount(type, 0, "rootfs", NULL); | |
3062 | put_filesystem(type); | |
1da177e4 LT |
3063 | if (IS_ERR(mnt)) |
3064 | panic("Can't create rootfs"); | |
b3e19d92 | 3065 | |
3b22edc5 TM |
3066 | ns = create_mnt_ns(mnt); |
3067 | if (IS_ERR(ns)) | |
1da177e4 | 3068 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
3069 | |
3070 | init_task.nsproxy->mnt_ns = ns; | |
3071 | get_mnt_ns(ns); | |
3072 | ||
be08d6d2 AV |
3073 | root.mnt = mnt; |
3074 | root.dentry = mnt->mnt_root; | |
da362b09 | 3075 | mnt->mnt_flags |= MNT_LOCKED; |
ac748a09 JB |
3076 | |
3077 | set_fs_pwd(current->fs, &root); | |
3078 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
3079 | } |
3080 | ||
74bf17cf | 3081 | void __init mnt_init(void) |
1da177e4 | 3082 | { |
13f14b4d | 3083 | unsigned u; |
15a67dd8 | 3084 | int err; |
1da177e4 | 3085 | |
7d6fec45 | 3086 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
20c2df83 | 3087 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 3088 | |
0818bf27 | 3089 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
38129a13 | 3090 | sizeof(struct hlist_head), |
0818bf27 AV |
3091 | mhash_entries, 19, |
3092 | 0, | |
3093 | &m_hash_shift, &m_hash_mask, 0, 0); | |
3094 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", | |
3095 | sizeof(struct hlist_head), | |
3096 | mphash_entries, 19, | |
3097 | 0, | |
3098 | &mp_hash_shift, &mp_hash_mask, 0, 0); | |
1da177e4 | 3099 | |
84d17192 | 3100 | if (!mount_hashtable || !mountpoint_hashtable) |
1da177e4 LT |
3101 | panic("Failed to allocate mount hash table\n"); |
3102 | ||
0818bf27 | 3103 | for (u = 0; u <= m_hash_mask; u++) |
38129a13 | 3104 | INIT_HLIST_HEAD(&mount_hashtable[u]); |
0818bf27 AV |
3105 | for (u = 0; u <= mp_hash_mask; u++) |
3106 | INIT_HLIST_HEAD(&mountpoint_hashtable[u]); | |
1da177e4 | 3107 | |
4b93dc9b TH |
3108 | kernfs_init(); |
3109 | ||
15a67dd8 RD |
3110 | err = sysfs_init(); |
3111 | if (err) | |
3112 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 3113 | __func__, err); |
00d26666 GKH |
3114 | fs_kobj = kobject_create_and_add("fs", NULL); |
3115 | if (!fs_kobj) | |
8e24eea7 | 3116 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
3117 | init_rootfs(); |
3118 | init_mount_tree(); | |
3119 | } | |
3120 | ||
616511d0 | 3121 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 3122 | { |
d498b25a | 3123 | if (!atomic_dec_and_test(&ns->count)) |
616511d0 | 3124 | return; |
7b00ed6f | 3125 | drop_collected_mounts(&ns->root->mnt); |
771b1371 | 3126 | free_mnt_ns(ns); |
1da177e4 | 3127 | } |
9d412a43 AV |
3128 | |
3129 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) | |
3130 | { | |
423e0ab0 TC |
3131 | struct vfsmount *mnt; |
3132 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); | |
3133 | if (!IS_ERR(mnt)) { | |
3134 | /* | |
3135 | * it is a longterm mount, don't release mnt until | |
3136 | * we unmount before file sys is unregistered | |
3137 | */ | |
f7a99c5b | 3138 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
423e0ab0 TC |
3139 | } |
3140 | return mnt; | |
9d412a43 AV |
3141 | } |
3142 | EXPORT_SYMBOL_GPL(kern_mount_data); | |
423e0ab0 TC |
3143 | |
3144 | void kern_unmount(struct vfsmount *mnt) | |
3145 | { | |
3146 | /* release long term mount so mount point can be released */ | |
3147 | if (!IS_ERR_OR_NULL(mnt)) { | |
f7a99c5b | 3148 | real_mount(mnt)->mnt_ns = NULL; |
48a066e7 | 3149 | synchronize_rcu(); /* yecchhh... */ |
423e0ab0 TC |
3150 | mntput(mnt); |
3151 | } | |
3152 | } | |
3153 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 AV |
3154 | |
3155 | bool our_mnt(struct vfsmount *mnt) | |
3156 | { | |
143c8c91 | 3157 | return check_mnt(real_mount(mnt)); |
02125a82 | 3158 | } |
8823c079 | 3159 | |
3151527e EB |
3160 | bool current_chrooted(void) |
3161 | { | |
3162 | /* Does the current process have a non-standard root */ | |
3163 | struct path ns_root; | |
3164 | struct path fs_root; | |
3165 | bool chrooted; | |
3166 | ||
3167 | /* Find the namespace root */ | |
3168 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; | |
3169 | ns_root.dentry = ns_root.mnt->mnt_root; | |
3170 | path_get(&ns_root); | |
3171 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) | |
3172 | ; | |
3173 | ||
3174 | get_fs_root(current->fs, &fs_root); | |
3175 | ||
3176 | chrooted = !path_equal(&fs_root, &ns_root); | |
3177 | ||
3178 | path_put(&fs_root); | |
3179 | path_put(&ns_root); | |
3180 | ||
3181 | return chrooted; | |
3182 | } | |
3183 | ||
8c6cf9cc | 3184 | static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) |
87a8ebd6 EB |
3185 | { |
3186 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
8c6cf9cc | 3187 | int new_flags = *new_mnt_flags; |
87a8ebd6 | 3188 | struct mount *mnt; |
e51db735 | 3189 | bool visible = false; |
87a8ebd6 | 3190 | |
e51db735 EB |
3191 | if (unlikely(!ns)) |
3192 | return false; | |
3193 | ||
44bb4385 | 3194 | down_read(&namespace_sem); |
87a8ebd6 | 3195 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
e51db735 EB |
3196 | struct mount *child; |
3197 | if (mnt->mnt.mnt_sb->s_type != type) | |
3198 | continue; | |
3199 | ||
7e96c1b0 EB |
3200 | /* This mount is not fully visible if it's root directory |
3201 | * is not the root directory of the filesystem. | |
3202 | */ | |
3203 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) | |
3204 | continue; | |
3205 | ||
8c6cf9cc EB |
3206 | /* Verify the mount flags are equal to or more permissive |
3207 | * than the proposed new mount. | |
3208 | */ | |
3209 | if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && | |
3210 | !(new_flags & MNT_READONLY)) | |
3211 | continue; | |
3212 | if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && | |
3213 | !(new_flags & MNT_NODEV)) | |
3214 | continue; | |
3215 | if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && | |
3216 | ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) | |
3217 | continue; | |
3218 | ||
ceeb0e5d EB |
3219 | /* This mount is not fully visible if there are any |
3220 | * locked child mounts that cover anything except for | |
3221 | * empty directories. | |
e51db735 EB |
3222 | */ |
3223 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
3224 | struct inode *inode = child->mnt_mountpoint->d_inode; | |
ceeb0e5d EB |
3225 | /* Only worry about locked mounts */ |
3226 | if (!(mnt->mnt.mnt_flags & MNT_LOCKED)) | |
3227 | continue; | |
7236c85e EB |
3228 | /* Is the directory permanetly empty? */ |
3229 | if (!is_empty_dir_inode(inode)) | |
e51db735 | 3230 | goto next; |
87a8ebd6 | 3231 | } |
8c6cf9cc EB |
3232 | /* Preserve the locked attributes */ |
3233 | *new_mnt_flags |= mnt->mnt.mnt_flags & (MNT_LOCK_READONLY | \ | |
3234 | MNT_LOCK_NODEV | \ | |
3235 | MNT_LOCK_ATIME); | |
e51db735 EB |
3236 | visible = true; |
3237 | goto found; | |
3238 | next: ; | |
87a8ebd6 | 3239 | } |
e51db735 | 3240 | found: |
44bb4385 | 3241 | up_read(&namespace_sem); |
e51db735 | 3242 | return visible; |
87a8ebd6 EB |
3243 | } |
3244 | ||
64964528 | 3245 | static struct ns_common *mntns_get(struct task_struct *task) |
8823c079 | 3246 | { |
58be2825 | 3247 | struct ns_common *ns = NULL; |
8823c079 EB |
3248 | struct nsproxy *nsproxy; |
3249 | ||
728dba3a EB |
3250 | task_lock(task); |
3251 | nsproxy = task->nsproxy; | |
8823c079 | 3252 | if (nsproxy) { |
58be2825 AV |
3253 | ns = &nsproxy->mnt_ns->ns; |
3254 | get_mnt_ns(to_mnt_ns(ns)); | |
8823c079 | 3255 | } |
728dba3a | 3256 | task_unlock(task); |
8823c079 EB |
3257 | |
3258 | return ns; | |
3259 | } | |
3260 | ||
64964528 | 3261 | static void mntns_put(struct ns_common *ns) |
8823c079 | 3262 | { |
58be2825 | 3263 | put_mnt_ns(to_mnt_ns(ns)); |
8823c079 EB |
3264 | } |
3265 | ||
64964528 | 3266 | static int mntns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
8823c079 EB |
3267 | { |
3268 | struct fs_struct *fs = current->fs; | |
58be2825 | 3269 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns); |
8823c079 EB |
3270 | struct path root; |
3271 | ||
0c55cfc4 | 3272 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
c7b96acf EB |
3273 | !ns_capable(current_user_ns(), CAP_SYS_CHROOT) || |
3274 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) | |
ae11e0f1 | 3275 | return -EPERM; |
8823c079 EB |
3276 | |
3277 | if (fs->users != 1) | |
3278 | return -EINVAL; | |
3279 | ||
3280 | get_mnt_ns(mnt_ns); | |
3281 | put_mnt_ns(nsproxy->mnt_ns); | |
3282 | nsproxy->mnt_ns = mnt_ns; | |
3283 | ||
3284 | /* Find the root */ | |
3285 | root.mnt = &mnt_ns->root->mnt; | |
3286 | root.dentry = mnt_ns->root->mnt.mnt_root; | |
3287 | path_get(&root); | |
3288 | while(d_mountpoint(root.dentry) && follow_down_one(&root)) | |
3289 | ; | |
3290 | ||
3291 | /* Update the pwd and root */ | |
3292 | set_fs_pwd(fs, &root); | |
3293 | set_fs_root(fs, &root); | |
3294 | ||
3295 | path_put(&root); | |
3296 | return 0; | |
3297 | } | |
3298 | ||
3299 | const struct proc_ns_operations mntns_operations = { | |
3300 | .name = "mnt", | |
3301 | .type = CLONE_NEWNS, | |
3302 | .get = mntns_get, | |
3303 | .put = mntns_put, | |
3304 | .install = mntns_install, | |
3305 | }; |