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Commit | Line | Data |
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59bd9ded | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/fs/namespace.c | |
4 | * | |
5 | * (C) Copyright Al Viro 2000, 2001 | |
1da177e4 LT |
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> | |
5b825c3a | 18 | #include <linux/cred.h> |
73cd49ec | 19 | #include <linux/idr.h> |
57f150a5 | 20 | #include <linux/init.h> /* init_rootfs */ |
d10577a8 AV |
21 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
22 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ | |
a07b2000 | 23 | #include <linux/file.h> |
d10577a8 | 24 | #include <linux/uaccess.h> |
0bb80f24 | 25 | #include <linux/proc_ns.h> |
20b4fb48 | 26 | #include <linux/magic.h> |
57c8a661 | 27 | #include <linux/memblock.h> |
9ea459e1 | 28 | #include <linux/task_work.h> |
9164bb4a | 29 | #include <linux/sched/task.h> |
e262e32d | 30 | #include <uapi/linux/mount.h> |
9bc61ab1 | 31 | #include <linux/fs_context.h> |
037f11b4 | 32 | #include <linux/shmem_fs.h> |
9164bb4a | 33 | |
07b20889 | 34 | #include "pnode.h" |
948730b0 | 35 | #include "internal.h" |
1da177e4 | 36 | |
d2921684 EB |
37 | /* Maximum number of mounts in a mount namespace */ |
38 | unsigned int sysctl_mount_max __read_mostly = 100000; | |
39 | ||
0818bf27 AV |
40 | static unsigned int m_hash_mask __read_mostly; |
41 | static unsigned int m_hash_shift __read_mostly; | |
42 | static unsigned int mp_hash_mask __read_mostly; | |
43 | static unsigned int mp_hash_shift __read_mostly; | |
44 | ||
45 | static __initdata unsigned long mhash_entries; | |
46 | static int __init set_mhash_entries(char *str) | |
47 | { | |
48 | if (!str) | |
49 | return 0; | |
50 | mhash_entries = simple_strtoul(str, &str, 0); | |
51 | return 1; | |
52 | } | |
53 | __setup("mhash_entries=", set_mhash_entries); | |
54 | ||
55 | static __initdata unsigned long mphash_entries; | |
56 | static int __init set_mphash_entries(char *str) | |
57 | { | |
58 | if (!str) | |
59 | return 0; | |
60 | mphash_entries = simple_strtoul(str, &str, 0); | |
61 | return 1; | |
62 | } | |
63 | __setup("mphash_entries=", set_mphash_entries); | |
13f14b4d | 64 | |
c7999c36 | 65 | static u64 event; |
73cd49ec | 66 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 67 | static DEFINE_IDA(mnt_group_ida); |
1da177e4 | 68 | |
38129a13 | 69 | static struct hlist_head *mount_hashtable __read_mostly; |
0818bf27 | 70 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
e18b890b | 71 | static struct kmem_cache *mnt_cache __read_mostly; |
59aa0da8 | 72 | static DECLARE_RWSEM(namespace_sem); |
4edbe133 AV |
73 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
74 | static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ | |
1da177e4 | 75 | |
f87fd4c2 | 76 | /* /sys/fs */ |
00d26666 GKH |
77 | struct kobject *fs_kobj; |
78 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 79 | |
99b7db7b NP |
80 | /* |
81 | * vfsmount lock may be taken for read to prevent changes to the | |
82 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
83 | * up the tree. | |
84 | * | |
85 | * It should be taken for write in all cases where the vfsmount | |
86 | * tree or hash is modified or when a vfsmount structure is modified. | |
87 | */ | |
48a066e7 | 88 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
99b7db7b | 89 | |
d033cb67 CB |
90 | static inline void lock_mount_hash(void) |
91 | { | |
92 | write_seqlock(&mount_lock); | |
93 | } | |
94 | ||
95 | static inline void unlock_mount_hash(void) | |
96 | { | |
97 | write_sequnlock(&mount_lock); | |
98 | } | |
99 | ||
38129a13 | 100 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 101 | { |
b58fed8b RP |
102 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
103 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
0818bf27 AV |
104 | tmp = tmp + (tmp >> m_hash_shift); |
105 | return &mount_hashtable[tmp & m_hash_mask]; | |
106 | } | |
107 | ||
108 | static inline struct hlist_head *mp_hash(struct dentry *dentry) | |
109 | { | |
110 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); | |
111 | tmp = tmp + (tmp >> mp_hash_shift); | |
112 | return &mountpoint_hashtable[tmp & mp_hash_mask]; | |
1da177e4 LT |
113 | } |
114 | ||
b105e270 | 115 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec | 116 | { |
169b480e MW |
117 | int res = ida_alloc(&mnt_id_ida, GFP_KERNEL); |
118 | ||
119 | if (res < 0) | |
120 | return res; | |
121 | mnt->mnt_id = res; | |
122 | return 0; | |
73cd49ec MS |
123 | } |
124 | ||
b105e270 | 125 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 126 | { |
169b480e | 127 | ida_free(&mnt_id_ida, mnt->mnt_id); |
73cd49ec MS |
128 | } |
129 | ||
719f5d7f MS |
130 | /* |
131 | * Allocate a new peer group ID | |
719f5d7f | 132 | */ |
4b8b21f4 | 133 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 134 | { |
169b480e | 135 | int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL); |
f21f6220 | 136 | |
169b480e MW |
137 | if (res < 0) |
138 | return res; | |
139 | mnt->mnt_group_id = res; | |
140 | return 0; | |
719f5d7f MS |
141 | } |
142 | ||
143 | /* | |
144 | * Release a peer group ID | |
145 | */ | |
4b8b21f4 | 146 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 147 | { |
169b480e | 148 | ida_free(&mnt_group_ida, mnt->mnt_group_id); |
15169fe7 | 149 | mnt->mnt_group_id = 0; |
719f5d7f MS |
150 | } |
151 | ||
b3e19d92 NP |
152 | /* |
153 | * vfsmount lock must be held for read | |
154 | */ | |
83adc753 | 155 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
156 | { |
157 | #ifdef CONFIG_SMP | |
68e8a9fe | 158 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
159 | #else |
160 | preempt_disable(); | |
68e8a9fe | 161 | mnt->mnt_count += n; |
b3e19d92 NP |
162 | preempt_enable(); |
163 | #endif | |
164 | } | |
165 | ||
b3e19d92 NP |
166 | /* |
167 | * vfsmount lock must be held for write | |
168 | */ | |
edf7ddbf | 169 | int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
170 | { |
171 | #ifdef CONFIG_SMP | |
edf7ddbf | 172 | int count = 0; |
b3e19d92 NP |
173 | int cpu; |
174 | ||
175 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 176 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
177 | } |
178 | ||
179 | return count; | |
180 | #else | |
68e8a9fe | 181 | return mnt->mnt_count; |
b3e19d92 NP |
182 | #endif |
183 | } | |
184 | ||
b105e270 | 185 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 186 | { |
c63181e6 AV |
187 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
188 | if (mnt) { | |
73cd49ec MS |
189 | int err; |
190 | ||
c63181e6 | 191 | err = mnt_alloc_id(mnt); |
88b38782 LZ |
192 | if (err) |
193 | goto out_free_cache; | |
194 | ||
195 | if (name) { | |
fcc139ae | 196 | mnt->mnt_devname = kstrdup_const(name, GFP_KERNEL); |
c63181e6 | 197 | if (!mnt->mnt_devname) |
88b38782 | 198 | goto out_free_id; |
73cd49ec MS |
199 | } |
200 | ||
b3e19d92 | 201 | #ifdef CONFIG_SMP |
c63181e6 AV |
202 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
203 | if (!mnt->mnt_pcp) | |
b3e19d92 NP |
204 | goto out_free_devname; |
205 | ||
c63181e6 | 206 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
b3e19d92 | 207 | #else |
c63181e6 AV |
208 | mnt->mnt_count = 1; |
209 | mnt->mnt_writers = 0; | |
b3e19d92 NP |
210 | #endif |
211 | ||
38129a13 | 212 | INIT_HLIST_NODE(&mnt->mnt_hash); |
c63181e6 AV |
213 | INIT_LIST_HEAD(&mnt->mnt_child); |
214 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
215 | INIT_LIST_HEAD(&mnt->mnt_list); | |
216 | INIT_LIST_HEAD(&mnt->mnt_expire); | |
217 | INIT_LIST_HEAD(&mnt->mnt_share); | |
218 | INIT_LIST_HEAD(&mnt->mnt_slave_list); | |
219 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
0a5eb7c8 | 220 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
99b19d16 | 221 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
56cbb429 | 222 | INIT_HLIST_HEAD(&mnt->mnt_stuck_children); |
a6435940 | 223 | mnt->mnt.mnt_userns = &init_user_ns; |
1da177e4 | 224 | } |
c63181e6 | 225 | return mnt; |
88b38782 | 226 | |
d3ef3d73 NP |
227 | #ifdef CONFIG_SMP |
228 | out_free_devname: | |
fcc139ae | 229 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 230 | #endif |
88b38782 | 231 | out_free_id: |
c63181e6 | 232 | mnt_free_id(mnt); |
88b38782 | 233 | out_free_cache: |
c63181e6 | 234 | kmem_cache_free(mnt_cache, mnt); |
88b38782 | 235 | return NULL; |
1da177e4 LT |
236 | } |
237 | ||
3d733633 DH |
238 | /* |
239 | * Most r/o checks on a fs are for operations that take | |
240 | * discrete amounts of time, like a write() or unlink(). | |
241 | * We must keep track of when those operations start | |
242 | * (for permission checks) and when they end, so that | |
243 | * we can determine when writes are able to occur to | |
244 | * a filesystem. | |
245 | */ | |
246 | /* | |
247 | * __mnt_is_readonly: check whether a mount is read-only | |
248 | * @mnt: the mount to check for its write status | |
249 | * | |
250 | * This shouldn't be used directly ouside of the VFS. | |
251 | * It does not guarantee that the filesystem will stay | |
252 | * r/w, just that it is right *now*. This can not and | |
253 | * should not be used in place of IS_RDONLY(inode). | |
254 | * mnt_want/drop_write() will _keep_ the filesystem | |
255 | * r/w. | |
256 | */ | |
43f5e655 | 257 | bool __mnt_is_readonly(struct vfsmount *mnt) |
3d733633 | 258 | { |
43f5e655 | 259 | return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb); |
3d733633 DH |
260 | } |
261 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
262 | ||
83adc753 | 263 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 NP |
264 | { |
265 | #ifdef CONFIG_SMP | |
68e8a9fe | 266 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 267 | #else |
68e8a9fe | 268 | mnt->mnt_writers++; |
d3ef3d73 NP |
269 | #endif |
270 | } | |
3d733633 | 271 | |
83adc753 | 272 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 273 | { |
d3ef3d73 | 274 | #ifdef CONFIG_SMP |
68e8a9fe | 275 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 276 | #else |
68e8a9fe | 277 | mnt->mnt_writers--; |
d3ef3d73 | 278 | #endif |
3d733633 | 279 | } |
3d733633 | 280 | |
83adc753 | 281 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 282 | { |
d3ef3d73 NP |
283 | #ifdef CONFIG_SMP |
284 | unsigned int count = 0; | |
3d733633 | 285 | int cpu; |
3d733633 DH |
286 | |
287 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 288 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 289 | } |
3d733633 | 290 | |
d3ef3d73 NP |
291 | return count; |
292 | #else | |
293 | return mnt->mnt_writers; | |
294 | #endif | |
3d733633 DH |
295 | } |
296 | ||
4ed5e82f MS |
297 | static int mnt_is_readonly(struct vfsmount *mnt) |
298 | { | |
299 | if (mnt->mnt_sb->s_readonly_remount) | |
300 | return 1; | |
301 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ | |
302 | smp_rmb(); | |
303 | return __mnt_is_readonly(mnt); | |
304 | } | |
305 | ||
8366025e | 306 | /* |
eb04c282 JK |
307 | * Most r/o & frozen checks on a fs are for operations that take discrete |
308 | * amounts of time, like a write() or unlink(). We must keep track of when | |
309 | * those operations start (for permission checks) and when they end, so that we | |
310 | * can determine when writes are able to occur to a filesystem. | |
8366025e DH |
311 | */ |
312 | /** | |
eb04c282 | 313 | * __mnt_want_write - get write access to a mount without freeze protection |
83adc753 | 314 | * @m: the mount on which to take a write |
8366025e | 315 | * |
eb04c282 JK |
316 | * This tells the low-level filesystem that a write is about to be performed to |
317 | * it, and makes sure that writes are allowed (mnt it read-write) before | |
318 | * returning success. This operation does not protect against filesystem being | |
319 | * frozen. When the write operation is finished, __mnt_drop_write() must be | |
320 | * called. This is effectively a refcount. | |
8366025e | 321 | */ |
eb04c282 | 322 | int __mnt_want_write(struct vfsmount *m) |
8366025e | 323 | { |
83adc753 | 324 | struct mount *mnt = real_mount(m); |
3d733633 | 325 | int ret = 0; |
3d733633 | 326 | |
d3ef3d73 | 327 | preempt_disable(); |
c6653a83 | 328 | mnt_inc_writers(mnt); |
d3ef3d73 | 329 | /* |
c6653a83 | 330 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 NP |
331 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
332 | * incremented count after it has set MNT_WRITE_HOLD. | |
333 | */ | |
334 | smp_mb(); | |
6aa7de05 | 335 | while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) |
d3ef3d73 NP |
336 | cpu_relax(); |
337 | /* | |
338 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
339 | * be set to match its requirements. So we must not load that until | |
340 | * MNT_WRITE_HOLD is cleared. | |
341 | */ | |
342 | smp_rmb(); | |
4ed5e82f | 343 | if (mnt_is_readonly(m)) { |
c6653a83 | 344 | mnt_dec_writers(mnt); |
3d733633 | 345 | ret = -EROFS; |
3d733633 | 346 | } |
d3ef3d73 | 347 | preempt_enable(); |
eb04c282 JK |
348 | |
349 | return ret; | |
350 | } | |
351 | ||
352 | /** | |
353 | * mnt_want_write - get write access to a mount | |
354 | * @m: the mount on which to take a write | |
355 | * | |
356 | * This tells the low-level filesystem that a write is about to be performed to | |
357 | * it, and makes sure that writes are allowed (mount is read-write, filesystem | |
358 | * is not frozen) before returning success. When the write operation is | |
359 | * finished, mnt_drop_write() must be called. This is effectively a refcount. | |
360 | */ | |
361 | int mnt_want_write(struct vfsmount *m) | |
362 | { | |
363 | int ret; | |
364 | ||
365 | sb_start_write(m->mnt_sb); | |
366 | ret = __mnt_want_write(m); | |
367 | if (ret) | |
368 | sb_end_write(m->mnt_sb); | |
3d733633 | 369 | return ret; |
8366025e DH |
370 | } |
371 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
372 | ||
96029c4e NP |
373 | /** |
374 | * mnt_clone_write - get write access to a mount | |
375 | * @mnt: the mount on which to take a write | |
376 | * | |
377 | * This is effectively like mnt_want_write, except | |
378 | * it must only be used to take an extra write reference | |
379 | * on a mountpoint that we already know has a write reference | |
380 | * on it. This allows some optimisation. | |
381 | * | |
382 | * After finished, mnt_drop_write must be called as usual to | |
383 | * drop the reference. | |
384 | */ | |
385 | int mnt_clone_write(struct vfsmount *mnt) | |
386 | { | |
387 | /* superblock may be r/o */ | |
388 | if (__mnt_is_readonly(mnt)) | |
389 | return -EROFS; | |
390 | preempt_disable(); | |
83adc753 | 391 | mnt_inc_writers(real_mount(mnt)); |
96029c4e NP |
392 | preempt_enable(); |
393 | return 0; | |
394 | } | |
395 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
396 | ||
397 | /** | |
eb04c282 | 398 | * __mnt_want_write_file - get write access to a file's mount |
96029c4e NP |
399 | * @file: the file who's mount on which to take a write |
400 | * | |
eb04c282 | 401 | * This is like __mnt_want_write, but it takes a file and can |
96029c4e NP |
402 | * do some optimisations if the file is open for write already |
403 | */ | |
eb04c282 | 404 | int __mnt_want_write_file(struct file *file) |
96029c4e | 405 | { |
83f936c7 | 406 | if (!(file->f_mode & FMODE_WRITER)) |
eb04c282 | 407 | return __mnt_want_write(file->f_path.mnt); |
96029c4e NP |
408 | else |
409 | return mnt_clone_write(file->f_path.mnt); | |
410 | } | |
eb04c282 | 411 | |
7c6893e3 MS |
412 | /** |
413 | * mnt_want_write_file - get write access to a file's mount | |
414 | * @file: the file who's mount on which to take a write | |
415 | * | |
416 | * This is like mnt_want_write, but it takes a file and can | |
417 | * do some optimisations if the file is open for write already | |
7c6893e3 MS |
418 | */ |
419 | int mnt_want_write_file(struct file *file) | |
420 | { | |
421 | int ret; | |
422 | ||
a6795a58 | 423 | sb_start_write(file_inode(file)->i_sb); |
eb04c282 JK |
424 | ret = __mnt_want_write_file(file); |
425 | if (ret) | |
a6795a58 | 426 | sb_end_write(file_inode(file)->i_sb); |
7c6893e3 MS |
427 | return ret; |
428 | } | |
96029c4e NP |
429 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
430 | ||
8366025e | 431 | /** |
eb04c282 | 432 | * __mnt_drop_write - give up write access to a mount |
8366025e DH |
433 | * @mnt: the mount on which to give up write access |
434 | * | |
435 | * Tells the low-level filesystem that we are done | |
436 | * performing writes to it. Must be matched with | |
eb04c282 | 437 | * __mnt_want_write() call above. |
8366025e | 438 | */ |
eb04c282 | 439 | void __mnt_drop_write(struct vfsmount *mnt) |
8366025e | 440 | { |
d3ef3d73 | 441 | preempt_disable(); |
83adc753 | 442 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 443 | preempt_enable(); |
8366025e | 444 | } |
eb04c282 JK |
445 | |
446 | /** | |
447 | * mnt_drop_write - give up write access to a mount | |
448 | * @mnt: the mount on which to give up write access | |
449 | * | |
450 | * Tells the low-level filesystem that we are done performing writes to it and | |
451 | * also allows filesystem to be frozen again. Must be matched with | |
452 | * mnt_want_write() call above. | |
453 | */ | |
454 | void mnt_drop_write(struct vfsmount *mnt) | |
455 | { | |
456 | __mnt_drop_write(mnt); | |
457 | sb_end_write(mnt->mnt_sb); | |
458 | } | |
8366025e DH |
459 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
460 | ||
eb04c282 JK |
461 | void __mnt_drop_write_file(struct file *file) |
462 | { | |
463 | __mnt_drop_write(file->f_path.mnt); | |
464 | } | |
465 | ||
7c6893e3 MS |
466 | void mnt_drop_write_file(struct file *file) |
467 | { | |
a6795a58 | 468 | __mnt_drop_write_file(file); |
7c6893e3 MS |
469 | sb_end_write(file_inode(file)->i_sb); |
470 | } | |
2a79f17e AV |
471 | EXPORT_SYMBOL(mnt_drop_write_file); |
472 | ||
83adc753 | 473 | static int mnt_make_readonly(struct mount *mnt) |
8366025e | 474 | { |
3d733633 DH |
475 | int ret = 0; |
476 | ||
83adc753 | 477 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 478 | /* |
d3ef3d73 NP |
479 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
480 | * should be visible before we do. | |
3d733633 | 481 | */ |
d3ef3d73 NP |
482 | smp_mb(); |
483 | ||
3d733633 | 484 | /* |
d3ef3d73 NP |
485 | * With writers on hold, if this value is zero, then there are |
486 | * definitely no active writers (although held writers may subsequently | |
487 | * increment the count, they'll have to wait, and decrement it after | |
488 | * seeing MNT_READONLY). | |
489 | * | |
490 | * It is OK to have counter incremented on one CPU and decremented on | |
491 | * another: the sum will add up correctly. The danger would be when we | |
492 | * sum up each counter, if we read a counter before it is incremented, | |
493 | * but then read another CPU's count which it has been subsequently | |
494 | * decremented from -- we would see more decrements than we should. | |
495 | * MNT_WRITE_HOLD protects against this scenario, because | |
496 | * mnt_want_write first increments count, then smp_mb, then spins on | |
497 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
498 | * we're counting up here. | |
3d733633 | 499 | */ |
c6653a83 | 500 | if (mnt_get_writers(mnt) > 0) |
d3ef3d73 NP |
501 | ret = -EBUSY; |
502 | else | |
83adc753 | 503 | mnt->mnt.mnt_flags |= MNT_READONLY; |
d3ef3d73 NP |
504 | /* |
505 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
506 | * that become unheld will see MNT_READONLY. | |
507 | */ | |
508 | smp_wmb(); | |
83adc753 | 509 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
3d733633 | 510 | return ret; |
8366025e | 511 | } |
8366025e | 512 | |
4ed5e82f MS |
513 | int sb_prepare_remount_readonly(struct super_block *sb) |
514 | { | |
515 | struct mount *mnt; | |
516 | int err = 0; | |
517 | ||
8e8b8796 MS |
518 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
519 | if (atomic_long_read(&sb->s_remove_count)) | |
520 | return -EBUSY; | |
521 | ||
719ea2fb | 522 | lock_mount_hash(); |
4ed5e82f MS |
523 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
524 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { | |
525 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; | |
526 | smp_mb(); | |
527 | if (mnt_get_writers(mnt) > 0) { | |
528 | err = -EBUSY; | |
529 | break; | |
530 | } | |
531 | } | |
532 | } | |
8e8b8796 MS |
533 | if (!err && atomic_long_read(&sb->s_remove_count)) |
534 | err = -EBUSY; | |
535 | ||
4ed5e82f MS |
536 | if (!err) { |
537 | sb->s_readonly_remount = 1; | |
538 | smp_wmb(); | |
539 | } | |
540 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { | |
541 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) | |
542 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; | |
543 | } | |
719ea2fb | 544 | unlock_mount_hash(); |
4ed5e82f MS |
545 | |
546 | return err; | |
547 | } | |
548 | ||
b105e270 | 549 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 550 | { |
a6435940 CB |
551 | struct user_namespace *mnt_userns; |
552 | ||
553 | mnt_userns = mnt_user_ns(&mnt->mnt); | |
554 | if (mnt_userns != &init_user_ns) | |
555 | put_user_ns(mnt_userns); | |
fcc139ae | 556 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 557 | #ifdef CONFIG_SMP |
68e8a9fe | 558 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 559 | #endif |
b105e270 | 560 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
561 | } |
562 | ||
8ffcb32e DH |
563 | static void delayed_free_vfsmnt(struct rcu_head *head) |
564 | { | |
565 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); | |
566 | } | |
567 | ||
48a066e7 | 568 | /* call under rcu_read_lock */ |
294d71ff | 569 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
48a066e7 AV |
570 | { |
571 | struct mount *mnt; | |
572 | if (read_seqretry(&mount_lock, seq)) | |
294d71ff | 573 | return 1; |
48a066e7 | 574 | if (bastard == NULL) |
294d71ff | 575 | return 0; |
48a066e7 AV |
576 | mnt = real_mount(bastard); |
577 | mnt_add_count(mnt, 1); | |
119e1ef8 | 578 | smp_mb(); // see mntput_no_expire() |
48a066e7 | 579 | if (likely(!read_seqretry(&mount_lock, seq))) |
294d71ff | 580 | return 0; |
48a066e7 AV |
581 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
582 | mnt_add_count(mnt, -1); | |
294d71ff AV |
583 | return 1; |
584 | } | |
119e1ef8 AV |
585 | lock_mount_hash(); |
586 | if (unlikely(bastard->mnt_flags & MNT_DOOMED)) { | |
587 | mnt_add_count(mnt, -1); | |
588 | unlock_mount_hash(); | |
589 | return 1; | |
590 | } | |
591 | unlock_mount_hash(); | |
592 | /* caller will mntput() */ | |
294d71ff AV |
593 | return -1; |
594 | } | |
595 | ||
596 | /* call under rcu_read_lock */ | |
597 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) | |
598 | { | |
599 | int res = __legitimize_mnt(bastard, seq); | |
600 | if (likely(!res)) | |
601 | return true; | |
602 | if (unlikely(res < 0)) { | |
603 | rcu_read_unlock(); | |
604 | mntput(bastard); | |
605 | rcu_read_lock(); | |
48a066e7 | 606 | } |
48a066e7 AV |
607 | return false; |
608 | } | |
609 | ||
1da177e4 | 610 | /* |
474279dc | 611 | * find the first mount at @dentry on vfsmount @mnt. |
48a066e7 | 612 | * call under rcu_read_lock() |
1da177e4 | 613 | */ |
474279dc | 614 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 615 | { |
38129a13 | 616 | struct hlist_head *head = m_hash(mnt, dentry); |
474279dc AV |
617 | struct mount *p; |
618 | ||
38129a13 | 619 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
474279dc AV |
620 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
621 | return p; | |
622 | return NULL; | |
623 | } | |
624 | ||
a05964f3 | 625 | /* |
f015f126 DH |
626 | * lookup_mnt - Return the first child mount mounted at path |
627 | * | |
628 | * "First" means first mounted chronologically. If you create the | |
629 | * following mounts: | |
630 | * | |
631 | * mount /dev/sda1 /mnt | |
632 | * mount /dev/sda2 /mnt | |
633 | * mount /dev/sda3 /mnt | |
634 | * | |
635 | * Then lookup_mnt() on the base /mnt dentry in the root mount will | |
636 | * return successively the root dentry and vfsmount of /dev/sda1, then | |
637 | * /dev/sda2, then /dev/sda3, then NULL. | |
638 | * | |
639 | * lookup_mnt takes a reference to the found vfsmount. | |
a05964f3 | 640 | */ |
ca71cf71 | 641 | struct vfsmount *lookup_mnt(const struct path *path) |
a05964f3 | 642 | { |
c7105365 | 643 | struct mount *child_mnt; |
48a066e7 AV |
644 | struct vfsmount *m; |
645 | unsigned seq; | |
99b7db7b | 646 | |
48a066e7 AV |
647 | rcu_read_lock(); |
648 | do { | |
649 | seq = read_seqbegin(&mount_lock); | |
650 | child_mnt = __lookup_mnt(path->mnt, path->dentry); | |
651 | m = child_mnt ? &child_mnt->mnt : NULL; | |
652 | } while (!legitimize_mnt(m, seq)); | |
653 | rcu_read_unlock(); | |
654 | return m; | |
a05964f3 RP |
655 | } |
656 | ||
9f6c61f9 MS |
657 | static inline void lock_ns_list(struct mnt_namespace *ns) |
658 | { | |
659 | spin_lock(&ns->ns_lock); | |
660 | } | |
661 | ||
662 | static inline void unlock_ns_list(struct mnt_namespace *ns) | |
663 | { | |
664 | spin_unlock(&ns->ns_lock); | |
665 | } | |
666 | ||
667 | static inline bool mnt_is_cursor(struct mount *mnt) | |
668 | { | |
669 | return mnt->mnt.mnt_flags & MNT_CURSOR; | |
670 | } | |
671 | ||
7af1364f EB |
672 | /* |
673 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the | |
674 | * current mount namespace. | |
675 | * | |
676 | * The common case is dentries are not mountpoints at all and that | |
677 | * test is handled inline. For the slow case when we are actually | |
678 | * dealing with a mountpoint of some kind, walk through all of the | |
679 | * mounts in the current mount namespace and test to see if the dentry | |
680 | * is a mountpoint. | |
681 | * | |
682 | * The mount_hashtable is not usable in the context because we | |
683 | * need to identify all mounts that may be in the current mount | |
684 | * namespace not just a mount that happens to have some specified | |
685 | * parent mount. | |
686 | */ | |
687 | bool __is_local_mountpoint(struct dentry *dentry) | |
688 | { | |
689 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
690 | struct mount *mnt; | |
691 | bool is_covered = false; | |
692 | ||
7af1364f | 693 | down_read(&namespace_sem); |
9f6c61f9 | 694 | lock_ns_list(ns); |
7af1364f | 695 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
9f6c61f9 MS |
696 | if (mnt_is_cursor(mnt)) |
697 | continue; | |
7af1364f EB |
698 | is_covered = (mnt->mnt_mountpoint == dentry); |
699 | if (is_covered) | |
700 | break; | |
701 | } | |
9f6c61f9 | 702 | unlock_ns_list(ns); |
7af1364f | 703 | up_read(&namespace_sem); |
5ad05cc8 | 704 | |
7af1364f EB |
705 | return is_covered; |
706 | } | |
707 | ||
e2dfa935 | 708 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
84d17192 | 709 | { |
0818bf27 | 710 | struct hlist_head *chain = mp_hash(dentry); |
84d17192 AV |
711 | struct mountpoint *mp; |
712 | ||
0818bf27 | 713 | hlist_for_each_entry(mp, chain, m_hash) { |
84d17192 | 714 | if (mp->m_dentry == dentry) { |
84d17192 AV |
715 | mp->m_count++; |
716 | return mp; | |
717 | } | |
718 | } | |
e2dfa935 EB |
719 | return NULL; |
720 | } | |
721 | ||
3895dbf8 | 722 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
e2dfa935 | 723 | { |
3895dbf8 | 724 | struct mountpoint *mp, *new = NULL; |
e2dfa935 | 725 | int ret; |
84d17192 | 726 | |
3895dbf8 | 727 | if (d_mountpoint(dentry)) { |
1e9c75fb BC |
728 | /* might be worth a WARN_ON() */ |
729 | if (d_unlinked(dentry)) | |
730 | return ERR_PTR(-ENOENT); | |
3895dbf8 EB |
731 | mountpoint: |
732 | read_seqlock_excl(&mount_lock); | |
733 | mp = lookup_mountpoint(dentry); | |
734 | read_sequnlock_excl(&mount_lock); | |
735 | if (mp) | |
736 | goto done; | |
737 | } | |
738 | ||
739 | if (!new) | |
740 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); | |
741 | if (!new) | |
84d17192 AV |
742 | return ERR_PTR(-ENOMEM); |
743 | ||
3895dbf8 EB |
744 | |
745 | /* Exactly one processes may set d_mounted */ | |
eed81007 | 746 | ret = d_set_mounted(dentry); |
eed81007 | 747 | |
3895dbf8 EB |
748 | /* Someone else set d_mounted? */ |
749 | if (ret == -EBUSY) | |
750 | goto mountpoint; | |
751 | ||
752 | /* The dentry is not available as a mountpoint? */ | |
753 | mp = ERR_PTR(ret); | |
754 | if (ret) | |
755 | goto done; | |
756 | ||
757 | /* Add the new mountpoint to the hash table */ | |
758 | read_seqlock_excl(&mount_lock); | |
4edbe133 | 759 | new->m_dentry = dget(dentry); |
3895dbf8 EB |
760 | new->m_count = 1; |
761 | hlist_add_head(&new->m_hash, mp_hash(dentry)); | |
762 | INIT_HLIST_HEAD(&new->m_list); | |
763 | read_sequnlock_excl(&mount_lock); | |
764 | ||
765 | mp = new; | |
766 | new = NULL; | |
767 | done: | |
768 | kfree(new); | |
84d17192 AV |
769 | return mp; |
770 | } | |
771 | ||
4edbe133 AV |
772 | /* |
773 | * vfsmount lock must be held. Additionally, the caller is responsible | |
774 | * for serializing calls for given disposal list. | |
775 | */ | |
776 | static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) | |
84d17192 AV |
777 | { |
778 | if (!--mp->m_count) { | |
779 | struct dentry *dentry = mp->m_dentry; | |
0a5eb7c8 | 780 | BUG_ON(!hlist_empty(&mp->m_list)); |
84d17192 AV |
781 | spin_lock(&dentry->d_lock); |
782 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
783 | spin_unlock(&dentry->d_lock); | |
4edbe133 | 784 | dput_to_list(dentry, list); |
0818bf27 | 785 | hlist_del(&mp->m_hash); |
84d17192 AV |
786 | kfree(mp); |
787 | } | |
788 | } | |
789 | ||
4edbe133 AV |
790 | /* called with namespace_lock and vfsmount lock */ |
791 | static void put_mountpoint(struct mountpoint *mp) | |
792 | { | |
793 | __put_mountpoint(mp, &ex_mountpoints); | |
794 | } | |
795 | ||
143c8c91 | 796 | static inline int check_mnt(struct mount *mnt) |
1da177e4 | 797 | { |
6b3286ed | 798 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
799 | } |
800 | ||
99b7db7b NP |
801 | /* |
802 | * vfsmount lock must be held for write | |
803 | */ | |
6b3286ed | 804 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
805 | { |
806 | if (ns) { | |
807 | ns->event = ++event; | |
808 | wake_up_interruptible(&ns->poll); | |
809 | } | |
810 | } | |
811 | ||
99b7db7b NP |
812 | /* |
813 | * vfsmount lock must be held for write | |
814 | */ | |
6b3286ed | 815 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
816 | { |
817 | if (ns && ns->event != event) { | |
818 | ns->event = event; | |
819 | wake_up_interruptible(&ns->poll); | |
820 | } | |
821 | } | |
822 | ||
99b7db7b NP |
823 | /* |
824 | * vfsmount lock must be held for write | |
825 | */ | |
e4e59906 | 826 | static struct mountpoint *unhash_mnt(struct mount *mnt) |
419148da | 827 | { |
e4e59906 | 828 | struct mountpoint *mp; |
0714a533 | 829 | mnt->mnt_parent = mnt; |
a73324da | 830 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 831 | list_del_init(&mnt->mnt_child); |
38129a13 | 832 | hlist_del_init_rcu(&mnt->mnt_hash); |
0a5eb7c8 | 833 | hlist_del_init(&mnt->mnt_mp_list); |
e4e59906 | 834 | mp = mnt->mnt_mp; |
84d17192 | 835 | mnt->mnt_mp = NULL; |
e4e59906 | 836 | return mp; |
7bdb11de EB |
837 | } |
838 | ||
6a46c573 EB |
839 | /* |
840 | * vfsmount lock must be held for write | |
841 | */ | |
842 | static void umount_mnt(struct mount *mnt) | |
843 | { | |
e4e59906 | 844 | put_mountpoint(unhash_mnt(mnt)); |
6a46c573 EB |
845 | } |
846 | ||
99b7db7b NP |
847 | /* |
848 | * vfsmount lock must be held for write | |
849 | */ | |
84d17192 AV |
850 | void mnt_set_mountpoint(struct mount *mnt, |
851 | struct mountpoint *mp, | |
44d964d6 | 852 | struct mount *child_mnt) |
b90fa9ae | 853 | { |
84d17192 | 854 | mp->m_count++; |
3a2393d7 | 855 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
4edbe133 | 856 | child_mnt->mnt_mountpoint = mp->m_dentry; |
3a2393d7 | 857 | child_mnt->mnt_parent = mnt; |
84d17192 | 858 | child_mnt->mnt_mp = mp; |
0a5eb7c8 | 859 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
b90fa9ae RP |
860 | } |
861 | ||
1064f874 EB |
862 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
863 | { | |
864 | hlist_add_head_rcu(&mnt->mnt_hash, | |
865 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); | |
866 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
867 | } | |
868 | ||
99b7db7b NP |
869 | /* |
870 | * vfsmount lock must be held for write | |
871 | */ | |
84d17192 AV |
872 | static void attach_mnt(struct mount *mnt, |
873 | struct mount *parent, | |
874 | struct mountpoint *mp) | |
1da177e4 | 875 | { |
84d17192 | 876 | mnt_set_mountpoint(parent, mp, mnt); |
1064f874 | 877 | __attach_mnt(mnt, parent); |
b90fa9ae RP |
878 | } |
879 | ||
1064f874 | 880 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
12a5b529 | 881 | { |
1064f874 | 882 | struct mountpoint *old_mp = mnt->mnt_mp; |
1064f874 EB |
883 | struct mount *old_parent = mnt->mnt_parent; |
884 | ||
885 | list_del_init(&mnt->mnt_child); | |
886 | hlist_del_init(&mnt->mnt_mp_list); | |
887 | hlist_del_init_rcu(&mnt->mnt_hash); | |
888 | ||
889 | attach_mnt(mnt, parent, mp); | |
890 | ||
891 | put_mountpoint(old_mp); | |
1064f874 | 892 | mnt_add_count(old_parent, -1); |
12a5b529 AV |
893 | } |
894 | ||
b90fa9ae | 895 | /* |
99b7db7b | 896 | * vfsmount lock must be held for write |
b90fa9ae | 897 | */ |
1064f874 | 898 | static void commit_tree(struct mount *mnt) |
b90fa9ae | 899 | { |
0714a533 | 900 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 901 | struct mount *m; |
b90fa9ae | 902 | LIST_HEAD(head); |
143c8c91 | 903 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae | 904 | |
0714a533 | 905 | BUG_ON(parent == mnt); |
b90fa9ae | 906 | |
1a4eeaf2 | 907 | list_add_tail(&head, &mnt->mnt_list); |
f7a99c5b | 908 | list_for_each_entry(m, &head, mnt_list) |
143c8c91 | 909 | m->mnt_ns = n; |
f03c6599 | 910 | |
b90fa9ae RP |
911 | list_splice(&head, n->list.prev); |
912 | ||
d2921684 EB |
913 | n->mounts += n->pending_mounts; |
914 | n->pending_mounts = 0; | |
915 | ||
1064f874 | 916 | __attach_mnt(mnt, parent); |
6b3286ed | 917 | touch_mnt_namespace(n); |
1da177e4 LT |
918 | } |
919 | ||
909b0a88 | 920 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
1da177e4 | 921 | { |
6b41d536 AV |
922 | struct list_head *next = p->mnt_mounts.next; |
923 | if (next == &p->mnt_mounts) { | |
1da177e4 | 924 | while (1) { |
909b0a88 | 925 | if (p == root) |
1da177e4 | 926 | return NULL; |
6b41d536 AV |
927 | next = p->mnt_child.next; |
928 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 929 | break; |
0714a533 | 930 | p = p->mnt_parent; |
1da177e4 LT |
931 | } |
932 | } | |
6b41d536 | 933 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
934 | } |
935 | ||
315fc83e | 936 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 937 | { |
6b41d536 AV |
938 | struct list_head *prev = p->mnt_mounts.prev; |
939 | while (prev != &p->mnt_mounts) { | |
940 | p = list_entry(prev, struct mount, mnt_child); | |
941 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
942 | } |
943 | return p; | |
944 | } | |
945 | ||
8f291889 AV |
946 | /** |
947 | * vfs_create_mount - Create a mount for a configured superblock | |
948 | * @fc: The configuration context with the superblock attached | |
949 | * | |
950 | * Create a mount to an already configured superblock. If necessary, the | |
951 | * caller should invoke vfs_get_tree() before calling this. | |
952 | * | |
953 | * Note that this does not attach the mount to anything. | |
954 | */ | |
955 | struct vfsmount *vfs_create_mount(struct fs_context *fc) | |
9d412a43 | 956 | { |
b105e270 | 957 | struct mount *mnt; |
9d412a43 | 958 | |
8f291889 AV |
959 | if (!fc->root) |
960 | return ERR_PTR(-EINVAL); | |
9d412a43 | 961 | |
8f291889 | 962 | mnt = alloc_vfsmnt(fc->source ?: "none"); |
9d412a43 AV |
963 | if (!mnt) |
964 | return ERR_PTR(-ENOMEM); | |
965 | ||
8f291889 | 966 | if (fc->sb_flags & SB_KERNMOUNT) |
b105e270 | 967 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 | 968 | |
8f291889 AV |
969 | atomic_inc(&fc->root->d_sb->s_active); |
970 | mnt->mnt.mnt_sb = fc->root->d_sb; | |
971 | mnt->mnt.mnt_root = dget(fc->root); | |
972 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
973 | mnt->mnt_parent = mnt; | |
9d412a43 | 974 | |
719ea2fb | 975 | lock_mount_hash(); |
8f291889 | 976 | list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); |
719ea2fb | 977 | unlock_mount_hash(); |
b105e270 | 978 | return &mnt->mnt; |
9d412a43 | 979 | } |
8f291889 AV |
980 | EXPORT_SYMBOL(vfs_create_mount); |
981 | ||
982 | struct vfsmount *fc_mount(struct fs_context *fc) | |
983 | { | |
984 | int err = vfs_get_tree(fc); | |
985 | if (!err) { | |
986 | up_write(&fc->root->d_sb->s_umount); | |
987 | return vfs_create_mount(fc); | |
988 | } | |
989 | return ERR_PTR(err); | |
990 | } | |
991 | EXPORT_SYMBOL(fc_mount); | |
992 | ||
9bc61ab1 DH |
993 | struct vfsmount *vfs_kern_mount(struct file_system_type *type, |
994 | int flags, const char *name, | |
995 | void *data) | |
9d412a43 | 996 | { |
9bc61ab1 | 997 | struct fs_context *fc; |
8f291889 | 998 | struct vfsmount *mnt; |
9bc61ab1 | 999 | int ret = 0; |
9d412a43 AV |
1000 | |
1001 | if (!type) | |
3e1aeb00 | 1002 | return ERR_PTR(-EINVAL); |
9d412a43 | 1003 | |
9bc61ab1 DH |
1004 | fc = fs_context_for_mount(type, flags); |
1005 | if (IS_ERR(fc)) | |
1006 | return ERR_CAST(fc); | |
1007 | ||
3e1aeb00 DH |
1008 | if (name) |
1009 | ret = vfs_parse_fs_string(fc, "source", | |
1010 | name, strlen(name)); | |
9bc61ab1 DH |
1011 | if (!ret) |
1012 | ret = parse_monolithic_mount_data(fc, data); | |
1013 | if (!ret) | |
8f291889 AV |
1014 | mnt = fc_mount(fc); |
1015 | else | |
1016 | mnt = ERR_PTR(ret); | |
9d412a43 | 1017 | |
9bc61ab1 | 1018 | put_fs_context(fc); |
8f291889 | 1019 | return mnt; |
9d412a43 AV |
1020 | } |
1021 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
1022 | ||
93faccbb EB |
1023 | struct vfsmount * |
1024 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, | |
1025 | const char *name, void *data) | |
1026 | { | |
1027 | /* Until it is worked out how to pass the user namespace | |
1028 | * through from the parent mount to the submount don't support | |
1029 | * unprivileged mounts with submounts. | |
1030 | */ | |
1031 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) | |
1032 | return ERR_PTR(-EPERM); | |
1033 | ||
e462ec50 | 1034 | return vfs_kern_mount(type, SB_SUBMOUNT, name, data); |
93faccbb EB |
1035 | } |
1036 | EXPORT_SYMBOL_GPL(vfs_submount); | |
1037 | ||
87129cc0 | 1038 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 1039 | int flag) |
1da177e4 | 1040 | { |
87129cc0 | 1041 | struct super_block *sb = old->mnt.mnt_sb; |
be34d1a3 DH |
1042 | struct mount *mnt; |
1043 | int err; | |
1da177e4 | 1044 | |
be34d1a3 DH |
1045 | mnt = alloc_vfsmnt(old->mnt_devname); |
1046 | if (!mnt) | |
1047 | return ERR_PTR(-ENOMEM); | |
719f5d7f | 1048 | |
7a472ef4 | 1049 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
be34d1a3 DH |
1050 | mnt->mnt_group_id = 0; /* not a peer of original */ |
1051 | else | |
1052 | mnt->mnt_group_id = old->mnt_group_id; | |
b90fa9ae | 1053 | |
be34d1a3 DH |
1054 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
1055 | err = mnt_alloc_group_id(mnt); | |
1056 | if (err) | |
1057 | goto out_free; | |
1da177e4 | 1058 | } |
be34d1a3 | 1059 | |
16a34adb AV |
1060 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
1061 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); | |
5ff9d8a6 | 1062 | |
be34d1a3 | 1063 | atomic_inc(&sb->s_active); |
a6435940 CB |
1064 | mnt->mnt.mnt_userns = mnt_user_ns(&old->mnt); |
1065 | if (mnt->mnt.mnt_userns != &init_user_ns) | |
1066 | mnt->mnt.mnt_userns = get_user_ns(mnt->mnt.mnt_userns); | |
be34d1a3 DH |
1067 | mnt->mnt.mnt_sb = sb; |
1068 | mnt->mnt.mnt_root = dget(root); | |
1069 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1070 | mnt->mnt_parent = mnt; | |
719ea2fb | 1071 | lock_mount_hash(); |
be34d1a3 | 1072 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
719ea2fb | 1073 | unlock_mount_hash(); |
be34d1a3 | 1074 | |
7a472ef4 EB |
1075 | if ((flag & CL_SLAVE) || |
1076 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { | |
be34d1a3 DH |
1077 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
1078 | mnt->mnt_master = old; | |
1079 | CLEAR_MNT_SHARED(mnt); | |
1080 | } else if (!(flag & CL_PRIVATE)) { | |
1081 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) | |
1082 | list_add(&mnt->mnt_share, &old->mnt_share); | |
1083 | if (IS_MNT_SLAVE(old)) | |
1084 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
1085 | mnt->mnt_master = old->mnt_master; | |
5235d448 AV |
1086 | } else { |
1087 | CLEAR_MNT_SHARED(mnt); | |
be34d1a3 DH |
1088 | } |
1089 | if (flag & CL_MAKE_SHARED) | |
1090 | set_mnt_shared(mnt); | |
1091 | ||
1092 | /* stick the duplicate mount on the same expiry list | |
1093 | * as the original if that was on one */ | |
1094 | if (flag & CL_EXPIRE) { | |
1095 | if (!list_empty(&old->mnt_expire)) | |
1096 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
1097 | } | |
1098 | ||
cb338d06 | 1099 | return mnt; |
719f5d7f MS |
1100 | |
1101 | out_free: | |
8ffcb32e | 1102 | mnt_free_id(mnt); |
719f5d7f | 1103 | free_vfsmnt(mnt); |
be34d1a3 | 1104 | return ERR_PTR(err); |
1da177e4 LT |
1105 | } |
1106 | ||
9ea459e1 AV |
1107 | static void cleanup_mnt(struct mount *mnt) |
1108 | { | |
56cbb429 AV |
1109 | struct hlist_node *p; |
1110 | struct mount *m; | |
9ea459e1 | 1111 | /* |
56cbb429 AV |
1112 | * The warning here probably indicates that somebody messed |
1113 | * up a mnt_want/drop_write() pair. If this happens, the | |
1114 | * filesystem was probably unable to make r/w->r/o transitions. | |
9ea459e1 AV |
1115 | * The locking used to deal with mnt_count decrement provides barriers, |
1116 | * so mnt_get_writers() below is safe. | |
1117 | */ | |
1118 | WARN_ON(mnt_get_writers(mnt)); | |
1119 | if (unlikely(mnt->mnt_pins.first)) | |
1120 | mnt_pin_kill(mnt); | |
56cbb429 AV |
1121 | hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) { |
1122 | hlist_del(&m->mnt_umount); | |
1123 | mntput(&m->mnt); | |
1124 | } | |
9ea459e1 AV |
1125 | fsnotify_vfsmount_delete(&mnt->mnt); |
1126 | dput(mnt->mnt.mnt_root); | |
1127 | deactivate_super(mnt->mnt.mnt_sb); | |
1128 | mnt_free_id(mnt); | |
1129 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); | |
1130 | } | |
1131 | ||
1132 | static void __cleanup_mnt(struct rcu_head *head) | |
1133 | { | |
1134 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); | |
1135 | } | |
1136 | ||
1137 | static LLIST_HEAD(delayed_mntput_list); | |
1138 | static void delayed_mntput(struct work_struct *unused) | |
1139 | { | |
1140 | struct llist_node *node = llist_del_all(&delayed_mntput_list); | |
29785735 | 1141 | struct mount *m, *t; |
9ea459e1 | 1142 | |
29785735 BP |
1143 | llist_for_each_entry_safe(m, t, node, mnt_llist) |
1144 | cleanup_mnt(m); | |
9ea459e1 AV |
1145 | } |
1146 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); | |
1147 | ||
900148dc | 1148 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 1149 | { |
4edbe133 | 1150 | LIST_HEAD(list); |
edf7ddbf | 1151 | int count; |
4edbe133 | 1152 | |
48a066e7 | 1153 | rcu_read_lock(); |
9ea0a46c AV |
1154 | if (likely(READ_ONCE(mnt->mnt_ns))) { |
1155 | /* | |
1156 | * Since we don't do lock_mount_hash() here, | |
1157 | * ->mnt_ns can change under us. However, if it's | |
1158 | * non-NULL, then there's a reference that won't | |
1159 | * be dropped until after an RCU delay done after | |
1160 | * turning ->mnt_ns NULL. So if we observe it | |
1161 | * non-NULL under rcu_read_lock(), the reference | |
1162 | * we are dropping is not the final one. | |
1163 | */ | |
1164 | mnt_add_count(mnt, -1); | |
48a066e7 | 1165 | rcu_read_unlock(); |
f03c6599 | 1166 | return; |
b3e19d92 | 1167 | } |
719ea2fb | 1168 | lock_mount_hash(); |
119e1ef8 AV |
1169 | /* |
1170 | * make sure that if __legitimize_mnt() has not seen us grab | |
1171 | * mount_lock, we'll see their refcount increment here. | |
1172 | */ | |
1173 | smp_mb(); | |
9ea0a46c | 1174 | mnt_add_count(mnt, -1); |
edf7ddbf EB |
1175 | count = mnt_get_count(mnt); |
1176 | if (count != 0) { | |
1177 | WARN_ON(count < 0); | |
48a066e7 | 1178 | rcu_read_unlock(); |
719ea2fb | 1179 | unlock_mount_hash(); |
99b7db7b NP |
1180 | return; |
1181 | } | |
48a066e7 AV |
1182 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
1183 | rcu_read_unlock(); | |
1184 | unlock_mount_hash(); | |
1185 | return; | |
1186 | } | |
1187 | mnt->mnt.mnt_flags |= MNT_DOOMED; | |
1188 | rcu_read_unlock(); | |
962830df | 1189 | |
39f7c4db | 1190 | list_del(&mnt->mnt_instance); |
ce07d891 EB |
1191 | |
1192 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { | |
1193 | struct mount *p, *tmp; | |
1194 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { | |
4edbe133 | 1195 | __put_mountpoint(unhash_mnt(p), &list); |
56cbb429 | 1196 | hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children); |
ce07d891 EB |
1197 | } |
1198 | } | |
719ea2fb | 1199 | unlock_mount_hash(); |
4edbe133 | 1200 | shrink_dentry_list(&list); |
649a795a | 1201 | |
9ea459e1 AV |
1202 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
1203 | struct task_struct *task = current; | |
1204 | if (likely(!(task->flags & PF_KTHREAD))) { | |
1205 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); | |
91989c70 | 1206 | if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME)) |
9ea459e1 AV |
1207 | return; |
1208 | } | |
1209 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) | |
1210 | schedule_delayed_work(&delayed_mntput_work, 1); | |
1211 | return; | |
1212 | } | |
1213 | cleanup_mnt(mnt); | |
b3e19d92 | 1214 | } |
b3e19d92 NP |
1215 | |
1216 | void mntput(struct vfsmount *mnt) | |
1217 | { | |
1218 | if (mnt) { | |
863d684f | 1219 | struct mount *m = real_mount(mnt); |
b3e19d92 | 1220 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
863d684f AV |
1221 | if (unlikely(m->mnt_expiry_mark)) |
1222 | m->mnt_expiry_mark = 0; | |
1223 | mntput_no_expire(m); | |
b3e19d92 NP |
1224 | } |
1225 | } | |
1226 | EXPORT_SYMBOL(mntput); | |
1227 | ||
1228 | struct vfsmount *mntget(struct vfsmount *mnt) | |
1229 | { | |
1230 | if (mnt) | |
83adc753 | 1231 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
1232 | return mnt; |
1233 | } | |
1234 | EXPORT_SYMBOL(mntget); | |
1235 | ||
c6609c0a IK |
1236 | /* path_is_mountpoint() - Check if path is a mount in the current |
1237 | * namespace. | |
1238 | * | |
1239 | * d_mountpoint() can only be used reliably to establish if a dentry is | |
1240 | * not mounted in any namespace and that common case is handled inline. | |
1241 | * d_mountpoint() isn't aware of the possibility there may be multiple | |
1242 | * mounts using a given dentry in a different namespace. This function | |
1243 | * checks if the passed in path is a mountpoint rather than the dentry | |
1244 | * alone. | |
1245 | */ | |
1246 | bool path_is_mountpoint(const struct path *path) | |
1247 | { | |
1248 | unsigned seq; | |
1249 | bool res; | |
1250 | ||
1251 | if (!d_mountpoint(path->dentry)) | |
1252 | return false; | |
1253 | ||
1254 | rcu_read_lock(); | |
1255 | do { | |
1256 | seq = read_seqbegin(&mount_lock); | |
1257 | res = __path_is_mountpoint(path); | |
1258 | } while (read_seqretry(&mount_lock, seq)); | |
1259 | rcu_read_unlock(); | |
1260 | ||
1261 | return res; | |
1262 | } | |
1263 | EXPORT_SYMBOL(path_is_mountpoint); | |
1264 | ||
ca71cf71 | 1265 | struct vfsmount *mnt_clone_internal(const struct path *path) |
7b7b1ace | 1266 | { |
3064c356 AV |
1267 | struct mount *p; |
1268 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); | |
1269 | if (IS_ERR(p)) | |
1270 | return ERR_CAST(p); | |
1271 | p->mnt.mnt_flags |= MNT_INTERNAL; | |
1272 | return &p->mnt; | |
7b7b1ace | 1273 | } |
1da177e4 | 1274 | |
a1a2c409 | 1275 | #ifdef CONFIG_PROC_FS |
9f6c61f9 MS |
1276 | static struct mount *mnt_list_next(struct mnt_namespace *ns, |
1277 | struct list_head *p) | |
1278 | { | |
1279 | struct mount *mnt, *ret = NULL; | |
1280 | ||
1281 | lock_ns_list(ns); | |
1282 | list_for_each_continue(p, &ns->list) { | |
1283 | mnt = list_entry(p, typeof(*mnt), mnt_list); | |
1284 | if (!mnt_is_cursor(mnt)) { | |
1285 | ret = mnt; | |
1286 | break; | |
1287 | } | |
1288 | } | |
1289 | unlock_ns_list(ns); | |
1290 | ||
1291 | return ret; | |
1292 | } | |
1293 | ||
0226f492 | 1294 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
1da177e4 LT |
1295 | static void *m_start(struct seq_file *m, loff_t *pos) |
1296 | { | |
ede1bf0d | 1297 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1298 | struct list_head *prev; |
1da177e4 | 1299 | |
390c6843 | 1300 | down_read(&namespace_sem); |
9f6c61f9 MS |
1301 | if (!*pos) { |
1302 | prev = &p->ns->list; | |
1303 | } else { | |
1304 | prev = &p->cursor.mnt_list; | |
1305 | ||
1306 | /* Read after we'd reached the end? */ | |
1307 | if (list_empty(prev)) | |
1308 | return NULL; | |
c7999c36 AV |
1309 | } |
1310 | ||
9f6c61f9 | 1311 | return mnt_list_next(p->ns, prev); |
1da177e4 LT |
1312 | } |
1313 | ||
1314 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
1315 | { | |
ede1bf0d | 1316 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1317 | struct mount *mnt = v; |
b0765fb8 | 1318 | |
9f6c61f9 MS |
1319 | ++*pos; |
1320 | return mnt_list_next(p->ns, &mnt->mnt_list); | |
1da177e4 LT |
1321 | } |
1322 | ||
1323 | static void m_stop(struct seq_file *m, void *v) | |
1324 | { | |
9f6c61f9 MS |
1325 | struct proc_mounts *p = m->private; |
1326 | struct mount *mnt = v; | |
1327 | ||
1328 | lock_ns_list(p->ns); | |
1329 | if (mnt) | |
1330 | list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); | |
1331 | else | |
1332 | list_del_init(&p->cursor.mnt_list); | |
1333 | unlock_ns_list(p->ns); | |
390c6843 | 1334 | up_read(&namespace_sem); |
1da177e4 LT |
1335 | } |
1336 | ||
0226f492 | 1337 | static int m_show(struct seq_file *m, void *v) |
2d4d4864 | 1338 | { |
ede1bf0d | 1339 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1340 | struct mount *r = v; |
0226f492 | 1341 | return p->show(m, &r->mnt); |
1da177e4 LT |
1342 | } |
1343 | ||
a1a2c409 | 1344 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1345 | .start = m_start, |
1346 | .next = m_next, | |
1347 | .stop = m_stop, | |
0226f492 | 1348 | .show = m_show, |
b4629fe2 | 1349 | }; |
9f6c61f9 MS |
1350 | |
1351 | void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) | |
1352 | { | |
1353 | down_read(&namespace_sem); | |
1354 | lock_ns_list(ns); | |
1355 | list_del(&cursor->mnt_list); | |
1356 | unlock_ns_list(ns); | |
1357 | up_read(&namespace_sem); | |
1358 | } | |
a1a2c409 | 1359 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1360 | |
1da177e4 LT |
1361 | /** |
1362 | * may_umount_tree - check if a mount tree is busy | |
1363 | * @mnt: root of mount tree | |
1364 | * | |
1365 | * This is called to check if a tree of mounts has any | |
1366 | * open files, pwds, chroots or sub mounts that are | |
1367 | * busy. | |
1368 | */ | |
909b0a88 | 1369 | int may_umount_tree(struct vfsmount *m) |
1da177e4 | 1370 | { |
909b0a88 | 1371 | struct mount *mnt = real_mount(m); |
36341f64 RP |
1372 | int actual_refs = 0; |
1373 | int minimum_refs = 0; | |
315fc83e | 1374 | struct mount *p; |
909b0a88 | 1375 | BUG_ON(!m); |
1da177e4 | 1376 | |
b3e19d92 | 1377 | /* write lock needed for mnt_get_count */ |
719ea2fb | 1378 | lock_mount_hash(); |
909b0a88 | 1379 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
83adc753 | 1380 | actual_refs += mnt_get_count(p); |
1da177e4 | 1381 | minimum_refs += 2; |
1da177e4 | 1382 | } |
719ea2fb | 1383 | unlock_mount_hash(); |
1da177e4 LT |
1384 | |
1385 | if (actual_refs > minimum_refs) | |
e3474a8e | 1386 | return 0; |
1da177e4 | 1387 | |
e3474a8e | 1388 | return 1; |
1da177e4 LT |
1389 | } |
1390 | ||
1391 | EXPORT_SYMBOL(may_umount_tree); | |
1392 | ||
1393 | /** | |
1394 | * may_umount - check if a mount point is busy | |
1395 | * @mnt: root of mount | |
1396 | * | |
1397 | * This is called to check if a mount point has any | |
1398 | * open files, pwds, chroots or sub mounts. If the | |
1399 | * mount has sub mounts this will return busy | |
1400 | * regardless of whether the sub mounts are busy. | |
1401 | * | |
1402 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1403 | * give false negatives. The main reason why it's here is that we need | |
1404 | * a non-destructive way to look for easily umountable filesystems. | |
1405 | */ | |
1406 | int may_umount(struct vfsmount *mnt) | |
1407 | { | |
e3474a8e | 1408 | int ret = 1; |
8ad08d8a | 1409 | down_read(&namespace_sem); |
719ea2fb | 1410 | lock_mount_hash(); |
1ab59738 | 1411 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1412 | ret = 0; |
719ea2fb | 1413 | unlock_mount_hash(); |
8ad08d8a | 1414 | up_read(&namespace_sem); |
a05964f3 | 1415 | return ret; |
1da177e4 LT |
1416 | } |
1417 | ||
1418 | EXPORT_SYMBOL(may_umount); | |
1419 | ||
97216be0 | 1420 | static void namespace_unlock(void) |
70fbcdf4 | 1421 | { |
a3b3c562 | 1422 | struct hlist_head head; |
56cbb429 AV |
1423 | struct hlist_node *p; |
1424 | struct mount *m; | |
4edbe133 | 1425 | LIST_HEAD(list); |
97216be0 | 1426 | |
a3b3c562 | 1427 | hlist_move_list(&unmounted, &head); |
4edbe133 | 1428 | list_splice_init(&ex_mountpoints, &list); |
97216be0 | 1429 | |
97216be0 AV |
1430 | up_write(&namespace_sem); |
1431 | ||
4edbe133 AV |
1432 | shrink_dentry_list(&list); |
1433 | ||
a3b3c562 EB |
1434 | if (likely(hlist_empty(&head))) |
1435 | return; | |
1436 | ||
22cb7405 | 1437 | synchronize_rcu_expedited(); |
48a066e7 | 1438 | |
56cbb429 AV |
1439 | hlist_for_each_entry_safe(m, p, &head, mnt_umount) { |
1440 | hlist_del(&m->mnt_umount); | |
1441 | mntput(&m->mnt); | |
1442 | } | |
70fbcdf4 RP |
1443 | } |
1444 | ||
97216be0 | 1445 | static inline void namespace_lock(void) |
e3197d83 | 1446 | { |
97216be0 | 1447 | down_write(&namespace_sem); |
e3197d83 AV |
1448 | } |
1449 | ||
e819f152 EB |
1450 | enum umount_tree_flags { |
1451 | UMOUNT_SYNC = 1, | |
1452 | UMOUNT_PROPAGATE = 2, | |
e0c9c0af | 1453 | UMOUNT_CONNECTED = 4, |
e819f152 | 1454 | }; |
f2d0a123 EB |
1455 | |
1456 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) | |
1457 | { | |
1458 | /* Leaving mounts connected is only valid for lazy umounts */ | |
1459 | if (how & UMOUNT_SYNC) | |
1460 | return true; | |
1461 | ||
1462 | /* A mount without a parent has nothing to be connected to */ | |
1463 | if (!mnt_has_parent(mnt)) | |
1464 | return true; | |
1465 | ||
1466 | /* Because the reference counting rules change when mounts are | |
1467 | * unmounted and connected, umounted mounts may not be | |
1468 | * connected to mounted mounts. | |
1469 | */ | |
1470 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) | |
1471 | return true; | |
1472 | ||
1473 | /* Has it been requested that the mount remain connected? */ | |
1474 | if (how & UMOUNT_CONNECTED) | |
1475 | return false; | |
1476 | ||
1477 | /* Is the mount locked such that it needs to remain connected? */ | |
1478 | if (IS_MNT_LOCKED(mnt)) | |
1479 | return false; | |
1480 | ||
1481 | /* By default disconnect the mount */ | |
1482 | return true; | |
1483 | } | |
1484 | ||
99b7db7b | 1485 | /* |
48a066e7 | 1486 | * mount_lock must be held |
99b7db7b NP |
1487 | * namespace_sem must be held for write |
1488 | */ | |
e819f152 | 1489 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
1da177e4 | 1490 | { |
c003b26f | 1491 | LIST_HEAD(tmp_list); |
315fc83e | 1492 | struct mount *p; |
1da177e4 | 1493 | |
5d88457e EB |
1494 | if (how & UMOUNT_PROPAGATE) |
1495 | propagate_mount_unlock(mnt); | |
1496 | ||
c003b26f | 1497 | /* Gather the mounts to umount */ |
590ce4bc EB |
1498 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1499 | p->mnt.mnt_flags |= MNT_UMOUNT; | |
c003b26f | 1500 | list_move(&p->mnt_list, &tmp_list); |
590ce4bc | 1501 | } |
1da177e4 | 1502 | |
411a938b | 1503 | /* Hide the mounts from mnt_mounts */ |
c003b26f | 1504 | list_for_each_entry(p, &tmp_list, mnt_list) { |
88b368f2 | 1505 | list_del_init(&p->mnt_child); |
c003b26f | 1506 | } |
88b368f2 | 1507 | |
c003b26f | 1508 | /* Add propogated mounts to the tmp_list */ |
e819f152 | 1509 | if (how & UMOUNT_PROPAGATE) |
7b8a53fd | 1510 | propagate_umount(&tmp_list); |
a05964f3 | 1511 | |
c003b26f | 1512 | while (!list_empty(&tmp_list)) { |
d2921684 | 1513 | struct mnt_namespace *ns; |
ce07d891 | 1514 | bool disconnect; |
c003b26f | 1515 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
6776db3d | 1516 | list_del_init(&p->mnt_expire); |
1a4eeaf2 | 1517 | list_del_init(&p->mnt_list); |
d2921684 EB |
1518 | ns = p->mnt_ns; |
1519 | if (ns) { | |
1520 | ns->mounts--; | |
1521 | __touch_mnt_namespace(ns); | |
1522 | } | |
143c8c91 | 1523 | p->mnt_ns = NULL; |
e819f152 | 1524 | if (how & UMOUNT_SYNC) |
48a066e7 | 1525 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
87b95ce0 | 1526 | |
f2d0a123 | 1527 | disconnect = disconnect_mount(p, how); |
676da58d | 1528 | if (mnt_has_parent(p)) { |
81b6b061 | 1529 | mnt_add_count(p->mnt_parent, -1); |
ce07d891 EB |
1530 | if (!disconnect) { |
1531 | /* Don't forget about p */ | |
1532 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); | |
1533 | } else { | |
1534 | umount_mnt(p); | |
1535 | } | |
7c4b93d8 | 1536 | } |
0f0afb1d | 1537 | change_mnt_propagation(p, MS_PRIVATE); |
19a1c409 AV |
1538 | if (disconnect) |
1539 | hlist_add_head(&p->mnt_umount, &unmounted); | |
1da177e4 LT |
1540 | } |
1541 | } | |
1542 | ||
b54b9be7 | 1543 | static void shrink_submounts(struct mount *mnt); |
c35038be | 1544 | |
8d0347f6 DH |
1545 | static int do_umount_root(struct super_block *sb) |
1546 | { | |
1547 | int ret = 0; | |
1548 | ||
1549 | down_write(&sb->s_umount); | |
1550 | if (!sb_rdonly(sb)) { | |
1551 | struct fs_context *fc; | |
1552 | ||
1553 | fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY, | |
1554 | SB_RDONLY); | |
1555 | if (IS_ERR(fc)) { | |
1556 | ret = PTR_ERR(fc); | |
1557 | } else { | |
1558 | ret = parse_monolithic_mount_data(fc, NULL); | |
1559 | if (!ret) | |
1560 | ret = reconfigure_super(fc); | |
1561 | put_fs_context(fc); | |
1562 | } | |
1563 | } | |
1564 | up_write(&sb->s_umount); | |
1565 | return ret; | |
1566 | } | |
1567 | ||
1ab59738 | 1568 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1569 | { |
1ab59738 | 1570 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 LT |
1571 | int retval; |
1572 | ||
1ab59738 | 1573 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1574 | if (retval) |
1575 | return retval; | |
1576 | ||
1577 | /* | |
1578 | * Allow userspace to request a mountpoint be expired rather than | |
1579 | * unmounting unconditionally. Unmount only happens if: | |
1580 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1581 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1582 | */ | |
1583 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1584 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1585 | flags & (MNT_FORCE | MNT_DETACH)) |
1586 | return -EINVAL; | |
1587 | ||
b3e19d92 NP |
1588 | /* |
1589 | * probably don't strictly need the lock here if we examined | |
1590 | * all race cases, but it's a slowpath. | |
1591 | */ | |
719ea2fb | 1592 | lock_mount_hash(); |
83adc753 | 1593 | if (mnt_get_count(mnt) != 2) { |
719ea2fb | 1594 | unlock_mount_hash(); |
1da177e4 | 1595 | return -EBUSY; |
b3e19d92 | 1596 | } |
719ea2fb | 1597 | unlock_mount_hash(); |
1da177e4 | 1598 | |
863d684f | 1599 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
1da177e4 LT |
1600 | return -EAGAIN; |
1601 | } | |
1602 | ||
1603 | /* | |
1604 | * If we may have to abort operations to get out of this | |
1605 | * mount, and they will themselves hold resources we must | |
1606 | * allow the fs to do things. In the Unix tradition of | |
1607 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1608 | * might fail to complete on the first run through as other tasks | |
1609 | * must return, and the like. Thats for the mount program to worry | |
1610 | * about for the moment. | |
1611 | */ | |
1612 | ||
42faad99 | 1613 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1614 | sb->s_op->umount_begin(sb); |
42faad99 | 1615 | } |
1da177e4 LT |
1616 | |
1617 | /* | |
1618 | * No sense to grab the lock for this test, but test itself looks | |
1619 | * somewhat bogus. Suggestions for better replacement? | |
1620 | * Ho-hum... In principle, we might treat that as umount + switch | |
1621 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1622 | * Actually it makes sense, especially if rootfs would contain a | |
1623 | * /reboot - static binary that would close all descriptors and | |
1624 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1625 | */ | |
1ab59738 | 1626 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1627 | /* |
1628 | * Special case for "unmounting" root ... | |
1629 | * we just try to remount it readonly. | |
1630 | */ | |
bc6155d1 | 1631 | if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) |
a1480dcc | 1632 | return -EPERM; |
8d0347f6 | 1633 | return do_umount_root(sb); |
1da177e4 LT |
1634 | } |
1635 | ||
97216be0 | 1636 | namespace_lock(); |
719ea2fb | 1637 | lock_mount_hash(); |
1da177e4 | 1638 | |
25d202ed EB |
1639 | /* Recheck MNT_LOCKED with the locks held */ |
1640 | retval = -EINVAL; | |
1641 | if (mnt->mnt.mnt_flags & MNT_LOCKED) | |
1642 | goto out; | |
1643 | ||
1644 | event++; | |
48a066e7 | 1645 | if (flags & MNT_DETACH) { |
1a4eeaf2 | 1646 | if (!list_empty(&mnt->mnt_list)) |
e819f152 | 1647 | umount_tree(mnt, UMOUNT_PROPAGATE); |
1da177e4 | 1648 | retval = 0; |
48a066e7 AV |
1649 | } else { |
1650 | shrink_submounts(mnt); | |
1651 | retval = -EBUSY; | |
1652 | if (!propagate_mount_busy(mnt, 2)) { | |
1653 | if (!list_empty(&mnt->mnt_list)) | |
e819f152 | 1654 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
48a066e7 AV |
1655 | retval = 0; |
1656 | } | |
1da177e4 | 1657 | } |
25d202ed | 1658 | out: |
719ea2fb | 1659 | unlock_mount_hash(); |
e3197d83 | 1660 | namespace_unlock(); |
1da177e4 LT |
1661 | return retval; |
1662 | } | |
1663 | ||
80b5dce8 EB |
1664 | /* |
1665 | * __detach_mounts - lazily unmount all mounts on the specified dentry | |
1666 | * | |
1667 | * During unlink, rmdir, and d_drop it is possible to loose the path | |
1668 | * to an existing mountpoint, and wind up leaking the mount. | |
1669 | * detach_mounts allows lazily unmounting those mounts instead of | |
1670 | * leaking them. | |
1671 | * | |
1672 | * The caller may hold dentry->d_inode->i_mutex. | |
1673 | */ | |
1674 | void __detach_mounts(struct dentry *dentry) | |
1675 | { | |
1676 | struct mountpoint *mp; | |
1677 | struct mount *mnt; | |
1678 | ||
1679 | namespace_lock(); | |
3895dbf8 | 1680 | lock_mount_hash(); |
80b5dce8 | 1681 | mp = lookup_mountpoint(dentry); |
adc9b5c0 | 1682 | if (!mp) |
80b5dce8 EB |
1683 | goto out_unlock; |
1684 | ||
e06b933e | 1685 | event++; |
80b5dce8 EB |
1686 | while (!hlist_empty(&mp->m_list)) { |
1687 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); | |
ce07d891 | 1688 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
fe78fcc8 | 1689 | umount_mnt(mnt); |
56cbb429 | 1690 | hlist_add_head(&mnt->mnt_umount, &unmounted); |
ce07d891 | 1691 | } |
e0c9c0af | 1692 | else umount_tree(mnt, UMOUNT_CONNECTED); |
80b5dce8 | 1693 | } |
80b5dce8 EB |
1694 | put_mountpoint(mp); |
1695 | out_unlock: | |
3895dbf8 | 1696 | unlock_mount_hash(); |
80b5dce8 EB |
1697 | namespace_unlock(); |
1698 | } | |
1699 | ||
dd111b31 | 1700 | /* |
9b40bc90 AV |
1701 | * Is the caller allowed to modify his namespace? |
1702 | */ | |
1703 | static inline bool may_mount(void) | |
1704 | { | |
1705 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); | |
1706 | } | |
1707 | ||
df2474a2 | 1708 | #ifdef CONFIG_MANDATORY_FILE_LOCKING |
9e8925b6 JL |
1709 | static inline bool may_mandlock(void) |
1710 | { | |
95ace754 | 1711 | return capable(CAP_SYS_ADMIN); |
9e8925b6 | 1712 | } |
df2474a2 JL |
1713 | #else |
1714 | static inline bool may_mandlock(void) | |
1715 | { | |
1716 | pr_warn("VFS: \"mand\" mount option not supported"); | |
1717 | return false; | |
1718 | } | |
1719 | #endif | |
9e8925b6 | 1720 | |
25ccd24f | 1721 | static int can_umount(const struct path *path, int flags) |
1da177e4 | 1722 | { |
25ccd24f | 1723 | struct mount *mnt = real_mount(path->mnt); |
1da177e4 | 1724 | |
9b40bc90 AV |
1725 | if (!may_mount()) |
1726 | return -EPERM; | |
41525f56 | 1727 | if (path->dentry != path->mnt->mnt_root) |
25ccd24f | 1728 | return -EINVAL; |
143c8c91 | 1729 | if (!check_mnt(mnt)) |
25ccd24f | 1730 | return -EINVAL; |
25d202ed | 1731 | if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ |
25ccd24f | 1732 | return -EINVAL; |
b2f5d4dc | 1733 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
25ccd24f CH |
1734 | return -EPERM; |
1735 | return 0; | |
1736 | } | |
1737 | ||
a0a6df9a | 1738 | // caller is responsible for flags being sane |
25ccd24f CH |
1739 | int path_umount(struct path *path, int flags) |
1740 | { | |
1741 | struct mount *mnt = real_mount(path->mnt); | |
1742 | int ret; | |
1743 | ||
1744 | ret = can_umount(path, flags); | |
1745 | if (!ret) | |
1746 | ret = do_umount(mnt, flags); | |
1da177e4 | 1747 | |
429731b1 | 1748 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
41525f56 | 1749 | dput(path->dentry); |
900148dc | 1750 | mntput_no_expire(mnt); |
25ccd24f | 1751 | return ret; |
1da177e4 LT |
1752 | } |
1753 | ||
09267def | 1754 | static int ksys_umount(char __user *name, int flags) |
41525f56 CH |
1755 | { |
1756 | int lookup_flags = LOOKUP_MOUNTPOINT; | |
1757 | struct path path; | |
1758 | int ret; | |
1759 | ||
a0a6df9a AV |
1760 | // basic validity checks done first |
1761 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) | |
1762 | return -EINVAL; | |
1763 | ||
41525f56 CH |
1764 | if (!(flags & UMOUNT_NOFOLLOW)) |
1765 | lookup_flags |= LOOKUP_FOLLOW; | |
1766 | ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); | |
1767 | if (ret) | |
1768 | return ret; | |
1769 | return path_umount(&path, flags); | |
1770 | } | |
1771 | ||
3a18ef5c DB |
1772 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1773 | { | |
1774 | return ksys_umount(name, flags); | |
1775 | } | |
1776 | ||
1da177e4 LT |
1777 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
1778 | ||
1779 | /* | |
b58fed8b | 1780 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1781 | */ |
bdc480e3 | 1782 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1783 | { |
3a18ef5c | 1784 | return ksys_umount(name, 0); |
1da177e4 LT |
1785 | } |
1786 | ||
1787 | #endif | |
1788 | ||
4ce5d2b1 | 1789 | static bool is_mnt_ns_file(struct dentry *dentry) |
8823c079 | 1790 | { |
4ce5d2b1 | 1791 | /* Is this a proxy for a mount namespace? */ |
e149ed2b AV |
1792 | return dentry->d_op == &ns_dentry_operations && |
1793 | dentry->d_fsdata == &mntns_operations; | |
4ce5d2b1 EB |
1794 | } |
1795 | ||
213921f9 | 1796 | static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
58be2825 AV |
1797 | { |
1798 | return container_of(ns, struct mnt_namespace, ns); | |
1799 | } | |
1800 | ||
303cc571 CB |
1801 | struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) |
1802 | { | |
1803 | return &mnt->ns; | |
1804 | } | |
1805 | ||
4ce5d2b1 EB |
1806 | static bool mnt_ns_loop(struct dentry *dentry) |
1807 | { | |
1808 | /* Could bind mounting the mount namespace inode cause a | |
1809 | * mount namespace loop? | |
1810 | */ | |
1811 | struct mnt_namespace *mnt_ns; | |
1812 | if (!is_mnt_ns_file(dentry)) | |
1813 | return false; | |
1814 | ||
f77c8014 | 1815 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
8823c079 EB |
1816 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
1817 | } | |
1818 | ||
87129cc0 | 1819 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1820 | int flag) |
1da177e4 | 1821 | { |
84d17192 | 1822 | struct mount *res, *p, *q, *r, *parent; |
1da177e4 | 1823 | |
4ce5d2b1 EB |
1824 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
1825 | return ERR_PTR(-EINVAL); | |
1826 | ||
1827 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) | |
be34d1a3 | 1828 | return ERR_PTR(-EINVAL); |
9676f0c6 | 1829 | |
36341f64 | 1830 | res = q = clone_mnt(mnt, dentry, flag); |
be34d1a3 DH |
1831 | if (IS_ERR(q)) |
1832 | return q; | |
1833 | ||
a73324da | 1834 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1835 | |
1836 | p = mnt; | |
6b41d536 | 1837 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1838 | struct mount *s; |
7ec02ef1 | 1839 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1840 | continue; |
1841 | ||
909b0a88 | 1842 | for (s = r; s; s = next_mnt(s, r)) { |
4ce5d2b1 EB |
1843 | if (!(flag & CL_COPY_UNBINDABLE) && |
1844 | IS_MNT_UNBINDABLE(s)) { | |
df7342b2 EB |
1845 | if (s->mnt.mnt_flags & MNT_LOCKED) { |
1846 | /* Both unbindable and locked. */ | |
1847 | q = ERR_PTR(-EPERM); | |
1848 | goto out; | |
1849 | } else { | |
1850 | s = skip_mnt_tree(s); | |
1851 | continue; | |
1852 | } | |
4ce5d2b1 EB |
1853 | } |
1854 | if (!(flag & CL_COPY_MNT_NS_FILE) && | |
1855 | is_mnt_ns_file(s->mnt.mnt_root)) { | |
9676f0c6 RP |
1856 | s = skip_mnt_tree(s); |
1857 | continue; | |
1858 | } | |
0714a533 AV |
1859 | while (p != s->mnt_parent) { |
1860 | p = p->mnt_parent; | |
1861 | q = q->mnt_parent; | |
1da177e4 | 1862 | } |
87129cc0 | 1863 | p = s; |
84d17192 | 1864 | parent = q; |
87129cc0 | 1865 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
be34d1a3 DH |
1866 | if (IS_ERR(q)) |
1867 | goto out; | |
719ea2fb | 1868 | lock_mount_hash(); |
1a4eeaf2 | 1869 | list_add_tail(&q->mnt_list, &res->mnt_list); |
1064f874 | 1870 | attach_mnt(q, parent, p->mnt_mp); |
719ea2fb | 1871 | unlock_mount_hash(); |
1da177e4 LT |
1872 | } |
1873 | } | |
1874 | return res; | |
be34d1a3 | 1875 | out: |
1da177e4 | 1876 | if (res) { |
719ea2fb | 1877 | lock_mount_hash(); |
e819f152 | 1878 | umount_tree(res, UMOUNT_SYNC); |
719ea2fb | 1879 | unlock_mount_hash(); |
1da177e4 | 1880 | } |
be34d1a3 | 1881 | return q; |
1da177e4 LT |
1882 | } |
1883 | ||
be34d1a3 DH |
1884 | /* Caller should check returned pointer for errors */ |
1885 | ||
ca71cf71 | 1886 | struct vfsmount *collect_mounts(const struct path *path) |
8aec0809 | 1887 | { |
cb338d06 | 1888 | struct mount *tree; |
97216be0 | 1889 | namespace_lock(); |
cd4a4017 EB |
1890 | if (!check_mnt(real_mount(path->mnt))) |
1891 | tree = ERR_PTR(-EINVAL); | |
1892 | else | |
1893 | tree = copy_tree(real_mount(path->mnt), path->dentry, | |
1894 | CL_COPY_ALL | CL_PRIVATE); | |
328e6d90 | 1895 | namespace_unlock(); |
be34d1a3 | 1896 | if (IS_ERR(tree)) |
52e220d3 | 1897 | return ERR_CAST(tree); |
be34d1a3 | 1898 | return &tree->mnt; |
8aec0809 AV |
1899 | } |
1900 | ||
a07b2000 AV |
1901 | static void free_mnt_ns(struct mnt_namespace *); |
1902 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool); | |
1903 | ||
1904 | void dissolve_on_fput(struct vfsmount *mnt) | |
1905 | { | |
1906 | struct mnt_namespace *ns; | |
1907 | namespace_lock(); | |
1908 | lock_mount_hash(); | |
1909 | ns = real_mount(mnt)->mnt_ns; | |
44dfd84a DH |
1910 | if (ns) { |
1911 | if (is_anon_ns(ns)) | |
1912 | umount_tree(real_mount(mnt), UMOUNT_CONNECTED); | |
1913 | else | |
1914 | ns = NULL; | |
1915 | } | |
a07b2000 AV |
1916 | unlock_mount_hash(); |
1917 | namespace_unlock(); | |
44dfd84a DH |
1918 | if (ns) |
1919 | free_mnt_ns(ns); | |
a07b2000 AV |
1920 | } |
1921 | ||
8aec0809 AV |
1922 | void drop_collected_mounts(struct vfsmount *mnt) |
1923 | { | |
97216be0 | 1924 | namespace_lock(); |
719ea2fb | 1925 | lock_mount_hash(); |
9c8e0a1b | 1926 | umount_tree(real_mount(mnt), 0); |
719ea2fb | 1927 | unlock_mount_hash(); |
3ab6abee | 1928 | namespace_unlock(); |
8aec0809 AV |
1929 | } |
1930 | ||
c771d683 MS |
1931 | /** |
1932 | * clone_private_mount - create a private clone of a path | |
1933 | * | |
1934 | * This creates a new vfsmount, which will be the clone of @path. The new will | |
1935 | * not be attached anywhere in the namespace and will be private (i.e. changes | |
1936 | * to the originating mount won't be propagated into this). | |
1937 | * | |
1938 | * Release with mntput(). | |
1939 | */ | |
ca71cf71 | 1940 | struct vfsmount *clone_private_mount(const struct path *path) |
c771d683 MS |
1941 | { |
1942 | struct mount *old_mnt = real_mount(path->mnt); | |
1943 | struct mount *new_mnt; | |
1944 | ||
1945 | if (IS_MNT_UNBINDABLE(old_mnt)) | |
1946 | return ERR_PTR(-EINVAL); | |
1947 | ||
c771d683 | 1948 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
c771d683 MS |
1949 | if (IS_ERR(new_mnt)) |
1950 | return ERR_CAST(new_mnt); | |
1951 | ||
df820f8d MS |
1952 | /* Longterm mount to be removed by kern_unmount*() */ |
1953 | new_mnt->mnt_ns = MNT_NS_INTERNAL; | |
1954 | ||
c771d683 MS |
1955 | return &new_mnt->mnt; |
1956 | } | |
1957 | EXPORT_SYMBOL_GPL(clone_private_mount); | |
1958 | ||
1f707137 AV |
1959 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1960 | struct vfsmount *root) | |
1961 | { | |
1a4eeaf2 | 1962 | struct mount *mnt; |
1f707137 AV |
1963 | int res = f(root, arg); |
1964 | if (res) | |
1965 | return res; | |
1a4eeaf2 AV |
1966 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
1967 | res = f(&mnt->mnt, arg); | |
1f707137 AV |
1968 | if (res) |
1969 | return res; | |
1970 | } | |
1971 | return 0; | |
1972 | } | |
1973 | ||
3bd045cc AV |
1974 | static void lock_mnt_tree(struct mount *mnt) |
1975 | { | |
1976 | struct mount *p; | |
1977 | ||
1978 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
1979 | int flags = p->mnt.mnt_flags; | |
1980 | /* Don't allow unprivileged users to change mount flags */ | |
1981 | flags |= MNT_LOCK_ATIME; | |
1982 | ||
1983 | if (flags & MNT_READONLY) | |
1984 | flags |= MNT_LOCK_READONLY; | |
1985 | ||
1986 | if (flags & MNT_NODEV) | |
1987 | flags |= MNT_LOCK_NODEV; | |
1988 | ||
1989 | if (flags & MNT_NOSUID) | |
1990 | flags |= MNT_LOCK_NOSUID; | |
1991 | ||
1992 | if (flags & MNT_NOEXEC) | |
1993 | flags |= MNT_LOCK_NOEXEC; | |
1994 | /* Don't allow unprivileged users to reveal what is under a mount */ | |
1995 | if (list_empty(&p->mnt_expire)) | |
1996 | flags |= MNT_LOCKED; | |
1997 | p->mnt.mnt_flags = flags; | |
1998 | } | |
1999 | } | |
2000 | ||
4b8b21f4 | 2001 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 2002 | { |
315fc83e | 2003 | struct mount *p; |
719f5d7f | 2004 | |
909b0a88 | 2005 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
fc7be130 | 2006 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
4b8b21f4 | 2007 | mnt_release_group_id(p); |
719f5d7f MS |
2008 | } |
2009 | } | |
2010 | ||
4b8b21f4 | 2011 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 2012 | { |
315fc83e | 2013 | struct mount *p; |
719f5d7f | 2014 | |
909b0a88 | 2015 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
fc7be130 | 2016 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
4b8b21f4 | 2017 | int err = mnt_alloc_group_id(p); |
719f5d7f | 2018 | if (err) { |
4b8b21f4 | 2019 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
2020 | return err; |
2021 | } | |
2022 | } | |
2023 | } | |
2024 | ||
2025 | return 0; | |
2026 | } | |
2027 | ||
d2921684 EB |
2028 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
2029 | { | |
2030 | unsigned int max = READ_ONCE(sysctl_mount_max); | |
2031 | unsigned int mounts = 0, old, pending, sum; | |
2032 | struct mount *p; | |
2033 | ||
2034 | for (p = mnt; p; p = next_mnt(p, mnt)) | |
2035 | mounts++; | |
2036 | ||
2037 | old = ns->mounts; | |
2038 | pending = ns->pending_mounts; | |
2039 | sum = old + pending; | |
2040 | if ((old > sum) || | |
2041 | (pending > sum) || | |
2042 | (max < sum) || | |
2043 | (mounts > (max - sum))) | |
2044 | return -ENOSPC; | |
2045 | ||
2046 | ns->pending_mounts = pending + mounts; | |
2047 | return 0; | |
2048 | } | |
2049 | ||
b90fa9ae RP |
2050 | /* |
2051 | * @source_mnt : mount tree to be attached | |
21444403 RP |
2052 | * @nd : place the mount tree @source_mnt is attached |
2053 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
2054 | * store the parent mount and mountpoint dentry. | |
2055 | * (done when source_mnt is moved) | |
b90fa9ae RP |
2056 | * |
2057 | * NOTE: in the table below explains the semantics when a source mount | |
2058 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
2059 | * --------------------------------------------------------------------------- |
2060 | * | BIND MOUNT OPERATION | | |
2061 | * |************************************************************************** | |
2062 | * | source-->| shared | private | slave | unbindable | | |
2063 | * | dest | | | | | | |
2064 | * | | | | | | | | |
2065 | * | v | | | | | | |
2066 | * |************************************************************************** | |
2067 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
2068 | * | | | | | | | |
2069 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
2070 | * *************************************************************************** | |
b90fa9ae RP |
2071 | * A bind operation clones the source mount and mounts the clone on the |
2072 | * destination mount. | |
2073 | * | |
2074 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
2075 | * tree of the destination mount and the cloned mount is added to | |
2076 | * the peer group of the source mount. | |
2077 | * (+) the cloned mount is created under the destination mount and is marked | |
2078 | * as shared. The cloned mount is added to the peer group of the source | |
2079 | * mount. | |
5afe0022 RP |
2080 | * (+++) the mount is propagated to all the mounts in the propagation tree |
2081 | * of the destination mount and the cloned mount is made slave | |
2082 | * of the same master as that of the source mount. The cloned mount | |
2083 | * is marked as 'shared and slave'. | |
2084 | * (*) the cloned mount is made a slave of the same master as that of the | |
2085 | * source mount. | |
2086 | * | |
9676f0c6 RP |
2087 | * --------------------------------------------------------------------------- |
2088 | * | MOVE MOUNT OPERATION | | |
2089 | * |************************************************************************** | |
2090 | * | source-->| shared | private | slave | unbindable | | |
2091 | * | dest | | | | | | |
2092 | * | | | | | | | | |
2093 | * | v | | | | | | |
2094 | * |************************************************************************** | |
2095 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
2096 | * | | | | | | | |
2097 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
2098 | * *************************************************************************** | |
5afe0022 RP |
2099 | * |
2100 | * (+) the mount is moved to the destination. And is then propagated to | |
2101 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 2102 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
2103 | * (+++) the mount is moved to the destination and is then propagated to |
2104 | * all the mounts belonging to the destination mount's propagation tree. | |
2105 | * the mount is marked as 'shared and slave'. | |
2106 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
2107 | * |
2108 | * if the source mount is a tree, the operations explained above is | |
2109 | * applied to each mount in the tree. | |
2110 | * Must be called without spinlocks held, since this function can sleep | |
2111 | * in allocations. | |
2112 | */ | |
0fb54e50 | 2113 | static int attach_recursive_mnt(struct mount *source_mnt, |
84d17192 AV |
2114 | struct mount *dest_mnt, |
2115 | struct mountpoint *dest_mp, | |
2763d119 | 2116 | bool moving) |
b90fa9ae | 2117 | { |
3bd045cc | 2118 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
38129a13 | 2119 | HLIST_HEAD(tree_list); |
d2921684 | 2120 | struct mnt_namespace *ns = dest_mnt->mnt_ns; |
1064f874 | 2121 | struct mountpoint *smp; |
315fc83e | 2122 | struct mount *child, *p; |
38129a13 | 2123 | struct hlist_node *n; |
719f5d7f | 2124 | int err; |
b90fa9ae | 2125 | |
1064f874 EB |
2126 | /* Preallocate a mountpoint in case the new mounts need |
2127 | * to be tucked under other mounts. | |
2128 | */ | |
2129 | smp = get_mountpoint(source_mnt->mnt.mnt_root); | |
2130 | if (IS_ERR(smp)) | |
2131 | return PTR_ERR(smp); | |
2132 | ||
d2921684 | 2133 | /* Is there space to add these mounts to the mount namespace? */ |
2763d119 | 2134 | if (!moving) { |
d2921684 EB |
2135 | err = count_mounts(ns, source_mnt); |
2136 | if (err) | |
2137 | goto out; | |
2138 | } | |
2139 | ||
fc7be130 | 2140 | if (IS_MNT_SHARED(dest_mnt)) { |
0fb54e50 | 2141 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
2142 | if (err) |
2143 | goto out; | |
0b1b901b | 2144 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
f2ebb3a9 | 2145 | lock_mount_hash(); |
0b1b901b AV |
2146 | if (err) |
2147 | goto out_cleanup_ids; | |
909b0a88 | 2148 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
0f0afb1d | 2149 | set_mnt_shared(p); |
0b1b901b AV |
2150 | } else { |
2151 | lock_mount_hash(); | |
b90fa9ae | 2152 | } |
2763d119 AV |
2153 | if (moving) { |
2154 | unhash_mnt(source_mnt); | |
84d17192 | 2155 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
143c8c91 | 2156 | touch_mnt_namespace(source_mnt->mnt_ns); |
21444403 | 2157 | } else { |
44dfd84a DH |
2158 | if (source_mnt->mnt_ns) { |
2159 | /* move from anon - the caller will destroy */ | |
2160 | list_del_init(&source_mnt->mnt_ns->list); | |
2161 | } | |
84d17192 | 2162 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
1064f874 | 2163 | commit_tree(source_mnt); |
21444403 | 2164 | } |
b90fa9ae | 2165 | |
38129a13 | 2166 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
1d6a32ac | 2167 | struct mount *q; |
38129a13 | 2168 | hlist_del_init(&child->mnt_hash); |
1064f874 EB |
2169 | q = __lookup_mnt(&child->mnt_parent->mnt, |
2170 | child->mnt_mountpoint); | |
2171 | if (q) | |
2172 | mnt_change_mountpoint(child, smp, q); | |
3bd045cc AV |
2173 | /* Notice when we are propagating across user namespaces */ |
2174 | if (child->mnt_parent->mnt_ns->user_ns != user_ns) | |
2175 | lock_mnt_tree(child); | |
d728cf79 | 2176 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
1064f874 | 2177 | commit_tree(child); |
b90fa9ae | 2178 | } |
1064f874 | 2179 | put_mountpoint(smp); |
719ea2fb | 2180 | unlock_mount_hash(); |
99b7db7b | 2181 | |
b90fa9ae | 2182 | return 0; |
719f5d7f MS |
2183 | |
2184 | out_cleanup_ids: | |
f2ebb3a9 AV |
2185 | while (!hlist_empty(&tree_list)) { |
2186 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); | |
d2921684 | 2187 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
e819f152 | 2188 | umount_tree(child, UMOUNT_SYNC); |
f2ebb3a9 AV |
2189 | } |
2190 | unlock_mount_hash(); | |
0b1b901b | 2191 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f | 2192 | out: |
d2921684 | 2193 | ns->pending_mounts = 0; |
1064f874 EB |
2194 | |
2195 | read_seqlock_excl(&mount_lock); | |
2196 | put_mountpoint(smp); | |
2197 | read_sequnlock_excl(&mount_lock); | |
2198 | ||
719f5d7f | 2199 | return err; |
b90fa9ae RP |
2200 | } |
2201 | ||
84d17192 | 2202 | static struct mountpoint *lock_mount(struct path *path) |
b12cea91 AV |
2203 | { |
2204 | struct vfsmount *mnt; | |
84d17192 | 2205 | struct dentry *dentry = path->dentry; |
b12cea91 | 2206 | retry: |
5955102c | 2207 | inode_lock(dentry->d_inode); |
84d17192 | 2208 | if (unlikely(cant_mount(dentry))) { |
5955102c | 2209 | inode_unlock(dentry->d_inode); |
84d17192 | 2210 | return ERR_PTR(-ENOENT); |
b12cea91 | 2211 | } |
97216be0 | 2212 | namespace_lock(); |
b12cea91 | 2213 | mnt = lookup_mnt(path); |
84d17192 | 2214 | if (likely(!mnt)) { |
3895dbf8 | 2215 | struct mountpoint *mp = get_mountpoint(dentry); |
84d17192 | 2216 | if (IS_ERR(mp)) { |
97216be0 | 2217 | namespace_unlock(); |
5955102c | 2218 | inode_unlock(dentry->d_inode); |
84d17192 AV |
2219 | return mp; |
2220 | } | |
2221 | return mp; | |
2222 | } | |
97216be0 | 2223 | namespace_unlock(); |
5955102c | 2224 | inode_unlock(path->dentry->d_inode); |
b12cea91 AV |
2225 | path_put(path); |
2226 | path->mnt = mnt; | |
84d17192 | 2227 | dentry = path->dentry = dget(mnt->mnt_root); |
b12cea91 AV |
2228 | goto retry; |
2229 | } | |
2230 | ||
84d17192 | 2231 | static void unlock_mount(struct mountpoint *where) |
b12cea91 | 2232 | { |
84d17192 | 2233 | struct dentry *dentry = where->m_dentry; |
3895dbf8 EB |
2234 | |
2235 | read_seqlock_excl(&mount_lock); | |
84d17192 | 2236 | put_mountpoint(where); |
3895dbf8 EB |
2237 | read_sequnlock_excl(&mount_lock); |
2238 | ||
328e6d90 | 2239 | namespace_unlock(); |
5955102c | 2240 | inode_unlock(dentry->d_inode); |
b12cea91 AV |
2241 | } |
2242 | ||
84d17192 | 2243 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
1da177e4 | 2244 | { |
e462ec50 | 2245 | if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER) |
1da177e4 LT |
2246 | return -EINVAL; |
2247 | ||
e36cb0b8 DH |
2248 | if (d_is_dir(mp->m_dentry) != |
2249 | d_is_dir(mnt->mnt.mnt_root)) | |
1da177e4 LT |
2250 | return -ENOTDIR; |
2251 | ||
2763d119 | 2252 | return attach_recursive_mnt(mnt, p, mp, false); |
1da177e4 LT |
2253 | } |
2254 | ||
7a2e8a8f VA |
2255 | /* |
2256 | * Sanity check the flags to change_mnt_propagation. | |
2257 | */ | |
2258 | ||
e462ec50 | 2259 | static int flags_to_propagation_type(int ms_flags) |
7a2e8a8f | 2260 | { |
e462ec50 | 2261 | int type = ms_flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
2262 | |
2263 | /* Fail if any non-propagation flags are set */ | |
2264 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
2265 | return 0; | |
2266 | /* Only one propagation flag should be set */ | |
2267 | if (!is_power_of_2(type)) | |
2268 | return 0; | |
2269 | return type; | |
2270 | } | |
2271 | ||
07b20889 RP |
2272 | /* |
2273 | * recursively change the type of the mountpoint. | |
2274 | */ | |
e462ec50 | 2275 | static int do_change_type(struct path *path, int ms_flags) |
07b20889 | 2276 | { |
315fc83e | 2277 | struct mount *m; |
4b8b21f4 | 2278 | struct mount *mnt = real_mount(path->mnt); |
e462ec50 | 2279 | int recurse = ms_flags & MS_REC; |
7a2e8a8f | 2280 | int type; |
719f5d7f | 2281 | int err = 0; |
07b20889 | 2282 | |
2d92ab3c | 2283 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
2284 | return -EINVAL; |
2285 | ||
e462ec50 | 2286 | type = flags_to_propagation_type(ms_flags); |
7a2e8a8f VA |
2287 | if (!type) |
2288 | return -EINVAL; | |
2289 | ||
97216be0 | 2290 | namespace_lock(); |
719f5d7f MS |
2291 | if (type == MS_SHARED) { |
2292 | err = invent_group_ids(mnt, recurse); | |
2293 | if (err) | |
2294 | goto out_unlock; | |
2295 | } | |
2296 | ||
719ea2fb | 2297 | lock_mount_hash(); |
909b0a88 | 2298 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
0f0afb1d | 2299 | change_mnt_propagation(m, type); |
719ea2fb | 2300 | unlock_mount_hash(); |
719f5d7f MS |
2301 | |
2302 | out_unlock: | |
97216be0 | 2303 | namespace_unlock(); |
719f5d7f | 2304 | return err; |
07b20889 RP |
2305 | } |
2306 | ||
5ff9d8a6 EB |
2307 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
2308 | { | |
2309 | struct mount *child; | |
2310 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
2311 | if (!is_subdir(child->mnt_mountpoint, dentry)) | |
2312 | continue; | |
2313 | ||
2314 | if (child->mnt.mnt_flags & MNT_LOCKED) | |
2315 | return true; | |
2316 | } | |
2317 | return false; | |
2318 | } | |
2319 | ||
a07b2000 AV |
2320 | static struct mount *__do_loopback(struct path *old_path, int recurse) |
2321 | { | |
2322 | struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt); | |
2323 | ||
2324 | if (IS_MNT_UNBINDABLE(old)) | |
2325 | return mnt; | |
2326 | ||
2327 | if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) | |
2328 | return mnt; | |
2329 | ||
2330 | if (!recurse && has_locked_children(old, old_path->dentry)) | |
2331 | return mnt; | |
2332 | ||
2333 | if (recurse) | |
2334 | mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE); | |
2335 | else | |
2336 | mnt = clone_mnt(old, old_path->dentry, 0); | |
2337 | ||
2338 | if (!IS_ERR(mnt)) | |
2339 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
2340 | ||
2341 | return mnt; | |
2342 | } | |
2343 | ||
1da177e4 LT |
2344 | /* |
2345 | * do loopback mount. | |
2346 | */ | |
808d4e3c | 2347 | static int do_loopback(struct path *path, const char *old_name, |
2dafe1c4 | 2348 | int recurse) |
1da177e4 | 2349 | { |
2d92ab3c | 2350 | struct path old_path; |
a07b2000 | 2351 | struct mount *mnt = NULL, *parent; |
84d17192 | 2352 | struct mountpoint *mp; |
57eccb83 | 2353 | int err; |
1da177e4 LT |
2354 | if (!old_name || !*old_name) |
2355 | return -EINVAL; | |
815d405c | 2356 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
2357 | if (err) |
2358 | return err; | |
2359 | ||
8823c079 | 2360 | err = -EINVAL; |
4ce5d2b1 | 2361 | if (mnt_ns_loop(old_path.dentry)) |
dd111b31 | 2362 | goto out; |
8823c079 | 2363 | |
84d17192 | 2364 | mp = lock_mount(path); |
a07b2000 AV |
2365 | if (IS_ERR(mp)) { |
2366 | err = PTR_ERR(mp); | |
b12cea91 | 2367 | goto out; |
a07b2000 | 2368 | } |
b12cea91 | 2369 | |
84d17192 | 2370 | parent = real_mount(path->mnt); |
e149ed2b AV |
2371 | if (!check_mnt(parent)) |
2372 | goto out2; | |
2373 | ||
a07b2000 | 2374 | mnt = __do_loopback(&old_path, recurse); |
be34d1a3 DH |
2375 | if (IS_ERR(mnt)) { |
2376 | err = PTR_ERR(mnt); | |
e9c5d8a5 | 2377 | goto out2; |
be34d1a3 | 2378 | } |
ccd48bc7 | 2379 | |
84d17192 | 2380 | err = graft_tree(mnt, parent, mp); |
ccd48bc7 | 2381 | if (err) { |
719ea2fb | 2382 | lock_mount_hash(); |
e819f152 | 2383 | umount_tree(mnt, UMOUNT_SYNC); |
719ea2fb | 2384 | unlock_mount_hash(); |
5b83d2c5 | 2385 | } |
b12cea91 | 2386 | out2: |
84d17192 | 2387 | unlock_mount(mp); |
ccd48bc7 | 2388 | out: |
2d92ab3c | 2389 | path_put(&old_path); |
1da177e4 LT |
2390 | return err; |
2391 | } | |
2392 | ||
a07b2000 AV |
2393 | static struct file *open_detached_copy(struct path *path, bool recursive) |
2394 | { | |
2395 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; | |
2396 | struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true); | |
2397 | struct mount *mnt, *p; | |
2398 | struct file *file; | |
2399 | ||
2400 | if (IS_ERR(ns)) | |
2401 | return ERR_CAST(ns); | |
2402 | ||
2403 | namespace_lock(); | |
2404 | mnt = __do_loopback(path, recursive); | |
2405 | if (IS_ERR(mnt)) { | |
2406 | namespace_unlock(); | |
2407 | free_mnt_ns(ns); | |
2408 | return ERR_CAST(mnt); | |
2409 | } | |
2410 | ||
2411 | lock_mount_hash(); | |
2412 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
2413 | p->mnt_ns = ns; | |
2414 | ns->mounts++; | |
2415 | } | |
2416 | ns->root = mnt; | |
2417 | list_add_tail(&ns->list, &mnt->mnt_list); | |
2418 | mntget(&mnt->mnt); | |
2419 | unlock_mount_hash(); | |
2420 | namespace_unlock(); | |
2421 | ||
2422 | mntput(path->mnt); | |
2423 | path->mnt = &mnt->mnt; | |
2424 | file = dentry_open(path, O_PATH, current_cred()); | |
2425 | if (IS_ERR(file)) | |
2426 | dissolve_on_fput(path->mnt); | |
2427 | else | |
2428 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
2429 | return file; | |
2430 | } | |
2431 | ||
2658ce09 | 2432 | SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags) |
a07b2000 AV |
2433 | { |
2434 | struct file *file; | |
2435 | struct path path; | |
2436 | int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; | |
2437 | bool detached = flags & OPEN_TREE_CLONE; | |
2438 | int error; | |
2439 | int fd; | |
2440 | ||
2441 | BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); | |
2442 | ||
2443 | if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE | | |
2444 | AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE | | |
2445 | OPEN_TREE_CLOEXEC)) | |
2446 | return -EINVAL; | |
2447 | ||
2448 | if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE) | |
2449 | return -EINVAL; | |
2450 | ||
2451 | if (flags & AT_NO_AUTOMOUNT) | |
2452 | lookup_flags &= ~LOOKUP_AUTOMOUNT; | |
2453 | if (flags & AT_SYMLINK_NOFOLLOW) | |
2454 | lookup_flags &= ~LOOKUP_FOLLOW; | |
2455 | if (flags & AT_EMPTY_PATH) | |
2456 | lookup_flags |= LOOKUP_EMPTY; | |
2457 | ||
2458 | if (detached && !may_mount()) | |
2459 | return -EPERM; | |
2460 | ||
2461 | fd = get_unused_fd_flags(flags & O_CLOEXEC); | |
2462 | if (fd < 0) | |
2463 | return fd; | |
2464 | ||
2465 | error = user_path_at(dfd, filename, lookup_flags, &path); | |
2466 | if (unlikely(error)) { | |
2467 | file = ERR_PTR(error); | |
2468 | } else { | |
2469 | if (detached) | |
2470 | file = open_detached_copy(&path, flags & AT_RECURSIVE); | |
2471 | else | |
2472 | file = dentry_open(&path, O_PATH, current_cred()); | |
2473 | path_put(&path); | |
2474 | } | |
2475 | if (IS_ERR(file)) { | |
2476 | put_unused_fd(fd); | |
2477 | return PTR_ERR(file); | |
2478 | } | |
2479 | fd_install(fd, file); | |
2480 | return fd; | |
2481 | } | |
2482 | ||
43f5e655 DH |
2483 | /* |
2484 | * Don't allow locked mount flags to be cleared. | |
2485 | * | |
2486 | * No locks need to be held here while testing the various MNT_LOCK | |
2487 | * flags because those flags can never be cleared once they are set. | |
2488 | */ | |
2489 | static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2490 | { |
43f5e655 DH |
2491 | unsigned int fl = mnt->mnt.mnt_flags; |
2492 | ||
2493 | if ((fl & MNT_LOCK_READONLY) && | |
2494 | !(mnt_flags & MNT_READONLY)) | |
2495 | return false; | |
2496 | ||
2497 | if ((fl & MNT_LOCK_NODEV) && | |
2498 | !(mnt_flags & MNT_NODEV)) | |
2499 | return false; | |
2500 | ||
2501 | if ((fl & MNT_LOCK_NOSUID) && | |
2502 | !(mnt_flags & MNT_NOSUID)) | |
2503 | return false; | |
2504 | ||
2505 | if ((fl & MNT_LOCK_NOEXEC) && | |
2506 | !(mnt_flags & MNT_NOEXEC)) | |
2507 | return false; | |
2508 | ||
2509 | if ((fl & MNT_LOCK_ATIME) && | |
2510 | ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) | |
2511 | return false; | |
2e4b7fcd | 2512 | |
43f5e655 DH |
2513 | return true; |
2514 | } | |
2515 | ||
2516 | static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2517 | { |
43f5e655 | 2518 | bool readonly_request = (mnt_flags & MNT_READONLY); |
2e4b7fcd | 2519 | |
43f5e655 | 2520 | if (readonly_request == __mnt_is_readonly(&mnt->mnt)) |
2e4b7fcd DH |
2521 | return 0; |
2522 | ||
2523 | if (readonly_request) | |
43f5e655 DH |
2524 | return mnt_make_readonly(mnt); |
2525 | ||
68847c94 CB |
2526 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
2527 | return 0; | |
43f5e655 DH |
2528 | } |
2529 | ||
43f5e655 DH |
2530 | static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) |
2531 | { | |
43f5e655 DH |
2532 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
2533 | mnt->mnt.mnt_flags = mnt_flags; | |
2534 | touch_mnt_namespace(mnt->mnt_ns); | |
43f5e655 DH |
2535 | } |
2536 | ||
f8b92ba6 DD |
2537 | static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt) |
2538 | { | |
2539 | struct super_block *sb = mnt->mnt_sb; | |
2540 | ||
2541 | if (!__mnt_is_readonly(mnt) && | |
2542 | (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { | |
2543 | char *buf = (char *)__get_free_page(GFP_KERNEL); | |
2544 | char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM); | |
2545 | struct tm tm; | |
2546 | ||
2547 | time64_to_tm(sb->s_time_max, 0, &tm); | |
2548 | ||
0ecee669 EB |
2549 | pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n", |
2550 | sb->s_type->name, | |
2551 | is_mounted(mnt) ? "remounted" : "mounted", | |
2552 | mntpath, | |
f8b92ba6 DD |
2553 | tm.tm_year+1900, (unsigned long long)sb->s_time_max); |
2554 | ||
2555 | free_page((unsigned long)buf); | |
2556 | } | |
2557 | } | |
2558 | ||
43f5e655 DH |
2559 | /* |
2560 | * Handle reconfiguration of the mountpoint only without alteration of the | |
2561 | * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND | |
2562 | * to mount(2). | |
2563 | */ | |
2564 | static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags) | |
2565 | { | |
2566 | struct super_block *sb = path->mnt->mnt_sb; | |
2567 | struct mount *mnt = real_mount(path->mnt); | |
2568 | int ret; | |
2569 | ||
2570 | if (!check_mnt(mnt)) | |
2571 | return -EINVAL; | |
2572 | ||
2573 | if (path->dentry != mnt->mnt.mnt_root) | |
2574 | return -EINVAL; | |
2575 | ||
2576 | if (!can_change_locked_flags(mnt, mnt_flags)) | |
2577 | return -EPERM; | |
2578 | ||
e58ace1a CB |
2579 | /* |
2580 | * We're only checking whether the superblock is read-only not | |
2581 | * changing it, so only take down_read(&sb->s_umount). | |
2582 | */ | |
2583 | down_read(&sb->s_umount); | |
68847c94 | 2584 | lock_mount_hash(); |
43f5e655 DH |
2585 | ret = change_mount_ro_state(mnt, mnt_flags); |
2586 | if (ret == 0) | |
2587 | set_mount_attributes(mnt, mnt_flags); | |
68847c94 | 2588 | unlock_mount_hash(); |
e58ace1a | 2589 | up_read(&sb->s_umount); |
f8b92ba6 DD |
2590 | |
2591 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2592 | ||
43f5e655 | 2593 | return ret; |
2e4b7fcd DH |
2594 | } |
2595 | ||
1da177e4 LT |
2596 | /* |
2597 | * change filesystem flags. dir should be a physical root of filesystem. | |
2598 | * If you've mounted a non-root directory somewhere and want to do remount | |
2599 | * on it - tough luck. | |
2600 | */ | |
e462ec50 DH |
2601 | static int do_remount(struct path *path, int ms_flags, int sb_flags, |
2602 | int mnt_flags, void *data) | |
1da177e4 LT |
2603 | { |
2604 | int err; | |
2d92ab3c | 2605 | struct super_block *sb = path->mnt->mnt_sb; |
143c8c91 | 2606 | struct mount *mnt = real_mount(path->mnt); |
8d0347f6 | 2607 | struct fs_context *fc; |
1da177e4 | 2608 | |
143c8c91 | 2609 | if (!check_mnt(mnt)) |
1da177e4 LT |
2610 | return -EINVAL; |
2611 | ||
2d92ab3c | 2612 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
2613 | return -EINVAL; |
2614 | ||
43f5e655 | 2615 | if (!can_change_locked_flags(mnt, mnt_flags)) |
9566d674 | 2616 | return -EPERM; |
9566d674 | 2617 | |
8d0347f6 DH |
2618 | fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK); |
2619 | if (IS_ERR(fc)) | |
2620 | return PTR_ERR(fc); | |
ff36fe2c | 2621 | |
b330966f | 2622 | fc->oldapi = true; |
8d0347f6 DH |
2623 | err = parse_monolithic_mount_data(fc, data); |
2624 | if (!err) { | |
2625 | down_write(&sb->s_umount); | |
2626 | err = -EPERM; | |
2627 | if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { | |
2628 | err = reconfigure_super(fc); | |
68847c94 CB |
2629 | if (!err) { |
2630 | lock_mount_hash(); | |
8d0347f6 | 2631 | set_mount_attributes(mnt, mnt_flags); |
68847c94 CB |
2632 | unlock_mount_hash(); |
2633 | } | |
8d0347f6 DH |
2634 | } |
2635 | up_write(&sb->s_umount); | |
0e55a7cc | 2636 | } |
f8b92ba6 DD |
2637 | |
2638 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2639 | ||
8d0347f6 | 2640 | put_fs_context(fc); |
1da177e4 LT |
2641 | return err; |
2642 | } | |
2643 | ||
cbbe362c | 2644 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 2645 | { |
315fc83e | 2646 | struct mount *p; |
909b0a88 | 2647 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
fc7be130 | 2648 | if (IS_MNT_UNBINDABLE(p)) |
9676f0c6 RP |
2649 | return 1; |
2650 | } | |
2651 | return 0; | |
2652 | } | |
2653 | ||
44dfd84a DH |
2654 | /* |
2655 | * Check that there aren't references to earlier/same mount namespaces in the | |
2656 | * specified subtree. Such references can act as pins for mount namespaces | |
2657 | * that aren't checked by the mount-cycle checking code, thereby allowing | |
2658 | * cycles to be made. | |
2659 | */ | |
2660 | static bool check_for_nsfs_mounts(struct mount *subtree) | |
2661 | { | |
2662 | struct mount *p; | |
2663 | bool ret = false; | |
2664 | ||
2665 | lock_mount_hash(); | |
2666 | for (p = subtree; p; p = next_mnt(p, subtree)) | |
2667 | if (mnt_ns_loop(p->mnt.mnt_root)) | |
2668 | goto out; | |
2669 | ||
2670 | ret = true; | |
2671 | out: | |
2672 | unlock_mount_hash(); | |
2673 | return ret; | |
2674 | } | |
2675 | ||
2db154b3 | 2676 | static int do_move_mount(struct path *old_path, struct path *new_path) |
1da177e4 | 2677 | { |
44dfd84a | 2678 | struct mnt_namespace *ns; |
676da58d | 2679 | struct mount *p; |
0fb54e50 | 2680 | struct mount *old; |
2763d119 AV |
2681 | struct mount *parent; |
2682 | struct mountpoint *mp, *old_mp; | |
57eccb83 | 2683 | int err; |
44dfd84a | 2684 | bool attached; |
1da177e4 | 2685 | |
2db154b3 | 2686 | mp = lock_mount(new_path); |
84d17192 | 2687 | if (IS_ERR(mp)) |
2db154b3 | 2688 | return PTR_ERR(mp); |
cc53ce53 | 2689 | |
2db154b3 DH |
2690 | old = real_mount(old_path->mnt); |
2691 | p = real_mount(new_path->mnt); | |
2763d119 | 2692 | parent = old->mnt_parent; |
44dfd84a | 2693 | attached = mnt_has_parent(old); |
2763d119 | 2694 | old_mp = old->mnt_mp; |
44dfd84a | 2695 | ns = old->mnt_ns; |
143c8c91 | 2696 | |
1da177e4 | 2697 | err = -EINVAL; |
44dfd84a DH |
2698 | /* The mountpoint must be in our namespace. */ |
2699 | if (!check_mnt(p)) | |
2db154b3 | 2700 | goto out; |
1da177e4 | 2701 | |
570d7a98 EB |
2702 | /* The thing moved must be mounted... */ |
2703 | if (!is_mounted(&old->mnt)) | |
44dfd84a DH |
2704 | goto out; |
2705 | ||
570d7a98 EB |
2706 | /* ... and either ours or the root of anon namespace */ |
2707 | if (!(attached ? check_mnt(old) : is_anon_ns(ns))) | |
2db154b3 | 2708 | goto out; |
5ff9d8a6 | 2709 | |
2db154b3 DH |
2710 | if (old->mnt.mnt_flags & MNT_LOCKED) |
2711 | goto out; | |
1da177e4 | 2712 | |
2db154b3 DH |
2713 | if (old_path->dentry != old_path->mnt->mnt_root) |
2714 | goto out; | |
1da177e4 | 2715 | |
2db154b3 DH |
2716 | if (d_is_dir(new_path->dentry) != |
2717 | d_is_dir(old_path->dentry)) | |
2718 | goto out; | |
21444403 RP |
2719 | /* |
2720 | * Don't move a mount residing in a shared parent. | |
2721 | */ | |
2763d119 | 2722 | if (attached && IS_MNT_SHARED(parent)) |
2db154b3 | 2723 | goto out; |
9676f0c6 RP |
2724 | /* |
2725 | * Don't move a mount tree containing unbindable mounts to a destination | |
2726 | * mount which is shared. | |
2727 | */ | |
fc7be130 | 2728 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
2db154b3 | 2729 | goto out; |
1da177e4 | 2730 | err = -ELOOP; |
44dfd84a DH |
2731 | if (!check_for_nsfs_mounts(old)) |
2732 | goto out; | |
fc7be130 | 2733 | for (; mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 2734 | if (p == old) |
2db154b3 | 2735 | goto out; |
1da177e4 | 2736 | |
2db154b3 | 2737 | err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, |
2763d119 | 2738 | attached); |
4ac91378 | 2739 | if (err) |
2db154b3 | 2740 | goto out; |
1da177e4 LT |
2741 | |
2742 | /* if the mount is moved, it should no longer be expire | |
2743 | * automatically */ | |
6776db3d | 2744 | list_del_init(&old->mnt_expire); |
2763d119 AV |
2745 | if (attached) |
2746 | put_mountpoint(old_mp); | |
1da177e4 | 2747 | out: |
2db154b3 | 2748 | unlock_mount(mp); |
44dfd84a | 2749 | if (!err) { |
2763d119 AV |
2750 | if (attached) |
2751 | mntput_no_expire(parent); | |
2752 | else | |
44dfd84a DH |
2753 | free_mnt_ns(ns); |
2754 | } | |
2db154b3 DH |
2755 | return err; |
2756 | } | |
2757 | ||
2758 | static int do_move_mount_old(struct path *path, const char *old_name) | |
2759 | { | |
2760 | struct path old_path; | |
2761 | int err; | |
2762 | ||
2763 | if (!old_name || !*old_name) | |
2764 | return -EINVAL; | |
2765 | ||
2766 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); | |
2767 | if (err) | |
2768 | return err; | |
2769 | ||
2770 | err = do_move_mount(&old_path, path); | |
2d92ab3c | 2771 | path_put(&old_path); |
1da177e4 LT |
2772 | return err; |
2773 | } | |
2774 | ||
9d412a43 AV |
2775 | /* |
2776 | * add a mount into a namespace's mount tree | |
2777 | */ | |
8f11538e AV |
2778 | static int do_add_mount(struct mount *newmnt, struct mountpoint *mp, |
2779 | struct path *path, int mnt_flags) | |
9d412a43 | 2780 | { |
8f11538e | 2781 | struct mount *parent = real_mount(path->mnt); |
9d412a43 | 2782 | |
f2ebb3a9 | 2783 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
9d412a43 | 2784 | |
84d17192 | 2785 | if (unlikely(!check_mnt(parent))) { |
156cacb1 AV |
2786 | /* that's acceptable only for automounts done in private ns */ |
2787 | if (!(mnt_flags & MNT_SHRINKABLE)) | |
8f11538e | 2788 | return -EINVAL; |
156cacb1 | 2789 | /* ... and for those we'd better have mountpoint still alive */ |
84d17192 | 2790 | if (!parent->mnt_ns) |
8f11538e | 2791 | return -EINVAL; |
156cacb1 | 2792 | } |
9d412a43 AV |
2793 | |
2794 | /* Refuse the same filesystem on the same mount point */ | |
95bc5f25 | 2795 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 | 2796 | path->mnt->mnt_root == path->dentry) |
8f11538e | 2797 | return -EBUSY; |
9d412a43 | 2798 | |
e36cb0b8 | 2799 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
8f11538e | 2800 | return -EINVAL; |
9d412a43 | 2801 | |
95bc5f25 | 2802 | newmnt->mnt.mnt_flags = mnt_flags; |
8f11538e | 2803 | return graft_tree(newmnt, parent, mp); |
9d412a43 | 2804 | } |
b1e75df4 | 2805 | |
132e4608 DH |
2806 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags); |
2807 | ||
2808 | /* | |
2809 | * Create a new mount using a superblock configuration and request it | |
2810 | * be added to the namespace tree. | |
2811 | */ | |
2812 | static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, | |
2813 | unsigned int mnt_flags) | |
2814 | { | |
2815 | struct vfsmount *mnt; | |
8f11538e | 2816 | struct mountpoint *mp; |
132e4608 DH |
2817 | struct super_block *sb = fc->root->d_sb; |
2818 | int error; | |
2819 | ||
c9ce29ed AV |
2820 | error = security_sb_kern_mount(sb); |
2821 | if (!error && mount_too_revealing(sb, &mnt_flags)) | |
2822 | error = -EPERM; | |
2823 | ||
2824 | if (unlikely(error)) { | |
2825 | fc_drop_locked(fc); | |
2826 | return error; | |
132e4608 DH |
2827 | } |
2828 | ||
2829 | up_write(&sb->s_umount); | |
2830 | ||
2831 | mnt = vfs_create_mount(fc); | |
2832 | if (IS_ERR(mnt)) | |
2833 | return PTR_ERR(mnt); | |
2834 | ||
f8b92ba6 DD |
2835 | mnt_warn_timestamp_expiry(mountpoint, mnt); |
2836 | ||
8f11538e AV |
2837 | mp = lock_mount(mountpoint); |
2838 | if (IS_ERR(mp)) { | |
2839 | mntput(mnt); | |
2840 | return PTR_ERR(mp); | |
2841 | } | |
2842 | error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags); | |
2843 | unlock_mount(mp); | |
0ecee669 EB |
2844 | if (error < 0) |
2845 | mntput(mnt); | |
132e4608 DH |
2846 | return error; |
2847 | } | |
1b852bce | 2848 | |
1da177e4 LT |
2849 | /* |
2850 | * create a new mount for userspace and request it to be added into the | |
2851 | * namespace's tree | |
2852 | */ | |
e462ec50 | 2853 | static int do_new_mount(struct path *path, const char *fstype, int sb_flags, |
808d4e3c | 2854 | int mnt_flags, const char *name, void *data) |
1da177e4 | 2855 | { |
0c55cfc4 | 2856 | struct file_system_type *type; |
a0c9a8b8 AV |
2857 | struct fs_context *fc; |
2858 | const char *subtype = NULL; | |
2859 | int err = 0; | |
1da177e4 | 2860 | |
0c55cfc4 | 2861 | if (!fstype) |
1da177e4 LT |
2862 | return -EINVAL; |
2863 | ||
0c55cfc4 EB |
2864 | type = get_fs_type(fstype); |
2865 | if (!type) | |
2866 | return -ENODEV; | |
2867 | ||
a0c9a8b8 AV |
2868 | if (type->fs_flags & FS_HAS_SUBTYPE) { |
2869 | subtype = strchr(fstype, '.'); | |
2870 | if (subtype) { | |
2871 | subtype++; | |
2872 | if (!*subtype) { | |
2873 | put_filesystem(type); | |
2874 | return -EINVAL; | |
2875 | } | |
a0c9a8b8 AV |
2876 | } |
2877 | } | |
0c55cfc4 | 2878 | |
a0c9a8b8 | 2879 | fc = fs_context_for_mount(type, sb_flags); |
0c55cfc4 | 2880 | put_filesystem(type); |
a0c9a8b8 AV |
2881 | if (IS_ERR(fc)) |
2882 | return PTR_ERR(fc); | |
2883 | ||
3e1aeb00 DH |
2884 | if (subtype) |
2885 | err = vfs_parse_fs_string(fc, "subtype", | |
2886 | subtype, strlen(subtype)); | |
2887 | if (!err && name) | |
2888 | err = vfs_parse_fs_string(fc, "source", name, strlen(name)); | |
a0c9a8b8 AV |
2889 | if (!err) |
2890 | err = parse_monolithic_mount_data(fc, data); | |
c3aabf07 AV |
2891 | if (!err && !mount_capable(fc)) |
2892 | err = -EPERM; | |
a0c9a8b8 AV |
2893 | if (!err) |
2894 | err = vfs_get_tree(fc); | |
132e4608 DH |
2895 | if (!err) |
2896 | err = do_new_mount_fc(fc, path, mnt_flags); | |
8654df4e | 2897 | |
a0c9a8b8 | 2898 | put_fs_context(fc); |
15f9a3f3 | 2899 | return err; |
1da177e4 LT |
2900 | } |
2901 | ||
19a167af AV |
2902 | int finish_automount(struct vfsmount *m, struct path *path) |
2903 | { | |
26df6034 | 2904 | struct dentry *dentry = path->dentry; |
8f11538e | 2905 | struct mountpoint *mp; |
25e195aa | 2906 | struct mount *mnt; |
19a167af | 2907 | int err; |
25e195aa AV |
2908 | |
2909 | if (!m) | |
2910 | return 0; | |
2911 | if (IS_ERR(m)) | |
2912 | return PTR_ERR(m); | |
2913 | ||
2914 | mnt = real_mount(m); | |
19a167af AV |
2915 | /* The new mount record should have at least 2 refs to prevent it being |
2916 | * expired before we get a chance to add it | |
2917 | */ | |
6776db3d | 2918 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
2919 | |
2920 | if (m->mnt_sb == path->mnt->mnt_sb && | |
26df6034 | 2921 | m->mnt_root == dentry) { |
b1e75df4 | 2922 | err = -ELOOP; |
26df6034 | 2923 | goto discard; |
19a167af AV |
2924 | } |
2925 | ||
26df6034 AV |
2926 | /* |
2927 | * we don't want to use lock_mount() - in this case finding something | |
2928 | * that overmounts our mountpoint to be means "quitely drop what we've | |
2929 | * got", not "try to mount it on top". | |
2930 | */ | |
2931 | inode_lock(dentry->d_inode); | |
2932 | namespace_lock(); | |
2933 | if (unlikely(cant_mount(dentry))) { | |
2934 | err = -ENOENT; | |
2935 | goto discard_locked; | |
2936 | } | |
2937 | rcu_read_lock(); | |
2938 | if (unlikely(__lookup_mnt(path->mnt, dentry))) { | |
2939 | rcu_read_unlock(); | |
2940 | err = 0; | |
2941 | goto discard_locked; | |
2942 | } | |
2943 | rcu_read_unlock(); | |
2944 | mp = get_mountpoint(dentry); | |
8f11538e AV |
2945 | if (IS_ERR(mp)) { |
2946 | err = PTR_ERR(mp); | |
26df6034 | 2947 | goto discard_locked; |
8f11538e | 2948 | } |
26df6034 | 2949 | |
8f11538e AV |
2950 | err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
2951 | unlock_mount(mp); | |
26df6034 AV |
2952 | if (unlikely(err)) |
2953 | goto discard; | |
2954 | mntput(m); | |
2955 | return 0; | |
2956 | ||
2957 | discard_locked: | |
2958 | namespace_unlock(); | |
2959 | inode_unlock(dentry->d_inode); | |
2960 | discard: | |
b1e75df4 | 2961 | /* remove m from any expiration list it may be on */ |
6776db3d | 2962 | if (!list_empty(&mnt->mnt_expire)) { |
97216be0 | 2963 | namespace_lock(); |
6776db3d | 2964 | list_del_init(&mnt->mnt_expire); |
97216be0 | 2965 | namespace_unlock(); |
19a167af | 2966 | } |
b1e75df4 AV |
2967 | mntput(m); |
2968 | mntput(m); | |
19a167af AV |
2969 | return err; |
2970 | } | |
2971 | ||
ea5b778a DH |
2972 | /** |
2973 | * mnt_set_expiry - Put a mount on an expiration list | |
2974 | * @mnt: The mount to list. | |
2975 | * @expiry_list: The list to add the mount to. | |
2976 | */ | |
2977 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
2978 | { | |
97216be0 | 2979 | namespace_lock(); |
ea5b778a | 2980 | |
6776db3d | 2981 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a | 2982 | |
97216be0 | 2983 | namespace_unlock(); |
ea5b778a DH |
2984 | } |
2985 | EXPORT_SYMBOL(mnt_set_expiry); | |
2986 | ||
1da177e4 LT |
2987 | /* |
2988 | * process a list of expirable mountpoints with the intent of discarding any | |
2989 | * mountpoints that aren't in use and haven't been touched since last we came | |
2990 | * here | |
2991 | */ | |
2992 | void mark_mounts_for_expiry(struct list_head *mounts) | |
2993 | { | |
761d5c38 | 2994 | struct mount *mnt, *next; |
1da177e4 LT |
2995 | LIST_HEAD(graveyard); |
2996 | ||
2997 | if (list_empty(mounts)) | |
2998 | return; | |
2999 | ||
97216be0 | 3000 | namespace_lock(); |
719ea2fb | 3001 | lock_mount_hash(); |
1da177e4 LT |
3002 | |
3003 | /* extract from the expiration list every vfsmount that matches the | |
3004 | * following criteria: | |
3005 | * - only referenced by its parent vfsmount | |
3006 | * - still marked for expiry (marked on the last call here; marks are | |
3007 | * cleared by mntput()) | |
3008 | */ | |
6776db3d | 3009 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
863d684f | 3010 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1ab59738 | 3011 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 3012 | continue; |
6776db3d | 3013 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 3014 | } |
bcc5c7d2 | 3015 | while (!list_empty(&graveyard)) { |
6776db3d | 3016 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
143c8c91 | 3017 | touch_mnt_namespace(mnt->mnt_ns); |
e819f152 | 3018 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 | 3019 | } |
719ea2fb | 3020 | unlock_mount_hash(); |
3ab6abee | 3021 | namespace_unlock(); |
5528f911 TM |
3022 | } |
3023 | ||
3024 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
3025 | ||
3026 | /* | |
3027 | * Ripoff of 'select_parent()' | |
3028 | * | |
3029 | * search the list of submounts for a given mountpoint, and move any | |
3030 | * shrinkable submounts to the 'graveyard' list. | |
3031 | */ | |
692afc31 | 3032 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 3033 | { |
692afc31 | 3034 | struct mount *this_parent = parent; |
5528f911 TM |
3035 | struct list_head *next; |
3036 | int found = 0; | |
3037 | ||
3038 | repeat: | |
6b41d536 | 3039 | next = this_parent->mnt_mounts.next; |
5528f911 | 3040 | resume: |
6b41d536 | 3041 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 3042 | struct list_head *tmp = next; |
6b41d536 | 3043 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
3044 | |
3045 | next = tmp->next; | |
692afc31 | 3046 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 3047 | continue; |
5528f911 TM |
3048 | /* |
3049 | * Descend a level if the d_mounts list is non-empty. | |
3050 | */ | |
6b41d536 | 3051 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
3052 | this_parent = mnt; |
3053 | goto repeat; | |
3054 | } | |
1da177e4 | 3055 | |
1ab59738 | 3056 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 3057 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
3058 | found++; |
3059 | } | |
1da177e4 | 3060 | } |
5528f911 TM |
3061 | /* |
3062 | * All done at this level ... ascend and resume the search | |
3063 | */ | |
3064 | if (this_parent != parent) { | |
6b41d536 | 3065 | next = this_parent->mnt_child.next; |
0714a533 | 3066 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
3067 | goto resume; |
3068 | } | |
3069 | return found; | |
3070 | } | |
3071 | ||
3072 | /* | |
3073 | * process a list of expirable mountpoints with the intent of discarding any | |
3074 | * submounts of a specific parent mountpoint | |
99b7db7b | 3075 | * |
48a066e7 | 3076 | * mount_lock must be held for write |
5528f911 | 3077 | */ |
b54b9be7 | 3078 | static void shrink_submounts(struct mount *mnt) |
5528f911 TM |
3079 | { |
3080 | LIST_HEAD(graveyard); | |
761d5c38 | 3081 | struct mount *m; |
5528f911 | 3082 | |
5528f911 | 3083 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 3084 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 3085 | while (!list_empty(&graveyard)) { |
761d5c38 | 3086 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 3087 | mnt_expire); |
143c8c91 | 3088 | touch_mnt_namespace(m->mnt_ns); |
e819f152 | 3089 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 AV |
3090 | } |
3091 | } | |
1da177e4 LT |
3092 | } |
3093 | ||
028abd92 | 3094 | static void *copy_mount_options(const void __user * data) |
1da177e4 | 3095 | { |
b40ef869 | 3096 | char *copy; |
d563d678 | 3097 | unsigned left, offset; |
b58fed8b | 3098 | |
1da177e4 | 3099 | if (!data) |
b40ef869 | 3100 | return NULL; |
1da177e4 | 3101 | |
b40ef869 AV |
3102 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
3103 | if (!copy) | |
3104 | return ERR_PTR(-ENOMEM); | |
1da177e4 | 3105 | |
d563d678 | 3106 | left = copy_from_user(copy, data, PAGE_SIZE); |
1da177e4 | 3107 | |
d563d678 CM |
3108 | /* |
3109 | * Not all architectures have an exact copy_from_user(). Resort to | |
3110 | * byte at a time. | |
3111 | */ | |
3112 | offset = PAGE_SIZE - left; | |
3113 | while (left) { | |
3114 | char c; | |
3115 | if (get_user(c, (const char __user *)data + offset)) | |
3116 | break; | |
3117 | copy[offset] = c; | |
3118 | left--; | |
3119 | offset++; | |
3120 | } | |
3121 | ||
3122 | if (left == PAGE_SIZE) { | |
b40ef869 AV |
3123 | kfree(copy); |
3124 | return ERR_PTR(-EFAULT); | |
1da177e4 | 3125 | } |
d563d678 | 3126 | |
b40ef869 | 3127 | return copy; |
1da177e4 LT |
3128 | } |
3129 | ||
028abd92 | 3130 | static char *copy_mount_string(const void __user *data) |
eca6f534 | 3131 | { |
fbdb4401 | 3132 | return data ? strndup_user(data, PATH_MAX) : NULL; |
eca6f534 VN |
3133 | } |
3134 | ||
1da177e4 LT |
3135 | /* |
3136 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
3137 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
3138 | * | |
3139 | * data is a (void *) that can point to any structure up to | |
3140 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
3141 | * information (or be NULL). | |
3142 | * | |
3143 | * Pre-0.97 versions of mount() didn't have a flags word. | |
3144 | * When the flags word was introduced its top half was required | |
3145 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
3146 | * Therefore, if this magic number is present, it carries no information | |
3147 | * and must be discarded. | |
3148 | */ | |
c60166f0 | 3149 | int path_mount(const char *dev_name, struct path *path, |
808d4e3c | 3150 | const char *type_page, unsigned long flags, void *data_page) |
1da177e4 | 3151 | { |
e462ec50 | 3152 | unsigned int mnt_flags = 0, sb_flags; |
a1e6aaa3 | 3153 | int ret; |
1da177e4 LT |
3154 | |
3155 | /* Discard magic */ | |
3156 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
3157 | flags &= ~MS_MGC_MSK; | |
3158 | ||
3159 | /* Basic sanity checks */ | |
1da177e4 LT |
3160 | if (data_page) |
3161 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
3162 | ||
e462ec50 DH |
3163 | if (flags & MS_NOUSER) |
3164 | return -EINVAL; | |
3165 | ||
a1e6aaa3 CH |
3166 | ret = security_sb_mount(dev_name, path, type_page, flags, data_page); |
3167 | if (ret) | |
3168 | return ret; | |
3169 | if (!may_mount()) | |
3170 | return -EPERM; | |
3171 | if ((flags & SB_MANDLOCK) && !may_mandlock()) | |
3172 | return -EPERM; | |
a27ab9f2 | 3173 | |
613cbe3d AK |
3174 | /* Default to relatime unless overriden */ |
3175 | if (!(flags & MS_NOATIME)) | |
3176 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 3177 | |
1da177e4 LT |
3178 | /* Separate the per-mountpoint flags */ |
3179 | if (flags & MS_NOSUID) | |
3180 | mnt_flags |= MNT_NOSUID; | |
3181 | if (flags & MS_NODEV) | |
3182 | mnt_flags |= MNT_NODEV; | |
3183 | if (flags & MS_NOEXEC) | |
3184 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
3185 | if (flags & MS_NOATIME) |
3186 | mnt_flags |= MNT_NOATIME; | |
3187 | if (flags & MS_NODIRATIME) | |
3188 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
3189 | if (flags & MS_STRICTATIME) |
3190 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
a9e5b732 | 3191 | if (flags & MS_RDONLY) |
2e4b7fcd | 3192 | mnt_flags |= MNT_READONLY; |
dab741e0 MN |
3193 | if (flags & MS_NOSYMFOLLOW) |
3194 | mnt_flags |= MNT_NOSYMFOLLOW; | |
fc33a7bb | 3195 | |
ffbc6f0e EB |
3196 | /* The default atime for remount is preservation */ |
3197 | if ((flags & MS_REMOUNT) && | |
3198 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | | |
3199 | MS_STRICTATIME)) == 0)) { | |
3200 | mnt_flags &= ~MNT_ATIME_MASK; | |
a1e6aaa3 | 3201 | mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; |
ffbc6f0e EB |
3202 | } |
3203 | ||
e462ec50 DH |
3204 | sb_flags = flags & (SB_RDONLY | |
3205 | SB_SYNCHRONOUS | | |
3206 | SB_MANDLOCK | | |
3207 | SB_DIRSYNC | | |
3208 | SB_SILENT | | |
917086ff | 3209 | SB_POSIXACL | |
d7ee9469 | 3210 | SB_LAZYTIME | |
917086ff | 3211 | SB_I_VERSION); |
1da177e4 | 3212 | |
43f5e655 | 3213 | if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) |
a1e6aaa3 CH |
3214 | return do_reconfigure_mnt(path, mnt_flags); |
3215 | if (flags & MS_REMOUNT) | |
3216 | return do_remount(path, flags, sb_flags, mnt_flags, data_page); | |
3217 | if (flags & MS_BIND) | |
3218 | return do_loopback(path, dev_name, flags & MS_REC); | |
3219 | if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
3220 | return do_change_type(path, flags); | |
3221 | if (flags & MS_MOVE) | |
3222 | return do_move_mount_old(path, dev_name); | |
3223 | ||
3224 | return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, | |
3225 | data_page); | |
3226 | } | |
3227 | ||
3228 | long do_mount(const char *dev_name, const char __user *dir_name, | |
3229 | const char *type_page, unsigned long flags, void *data_page) | |
3230 | { | |
3231 | struct path path; | |
3232 | int ret; | |
3233 | ||
3234 | ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); | |
3235 | if (ret) | |
3236 | return ret; | |
3237 | ret = path_mount(dev_name, &path, type_page, flags, data_page); | |
2d92ab3c | 3238 | path_put(&path); |
a1e6aaa3 | 3239 | return ret; |
1da177e4 LT |
3240 | } |
3241 | ||
537f7ccb EB |
3242 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
3243 | { | |
3244 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); | |
3245 | } | |
3246 | ||
3247 | static void dec_mnt_namespaces(struct ucounts *ucounts) | |
3248 | { | |
3249 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); | |
3250 | } | |
3251 | ||
771b1371 EB |
3252 | static void free_mnt_ns(struct mnt_namespace *ns) |
3253 | { | |
74e83122 AV |
3254 | if (!is_anon_ns(ns)) |
3255 | ns_free_inum(&ns->ns); | |
537f7ccb | 3256 | dec_mnt_namespaces(ns->ucounts); |
771b1371 EB |
3257 | put_user_ns(ns->user_ns); |
3258 | kfree(ns); | |
3259 | } | |
3260 | ||
8823c079 EB |
3261 | /* |
3262 | * Assign a sequence number so we can detect when we attempt to bind | |
3263 | * mount a reference to an older mount namespace into the current | |
3264 | * mount namespace, preventing reference counting loops. A 64bit | |
3265 | * number incrementing at 10Ghz will take 12,427 years to wrap which | |
3266 | * is effectively never, so we can ignore the possibility. | |
3267 | */ | |
3268 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); | |
3269 | ||
74e83122 | 3270 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon) |
cf8d2c11 TM |
3271 | { |
3272 | struct mnt_namespace *new_ns; | |
537f7ccb | 3273 | struct ucounts *ucounts; |
98f842e6 | 3274 | int ret; |
cf8d2c11 | 3275 | |
537f7ccb EB |
3276 | ucounts = inc_mnt_namespaces(user_ns); |
3277 | if (!ucounts) | |
df75e774 | 3278 | return ERR_PTR(-ENOSPC); |
537f7ccb | 3279 | |
74e83122 | 3280 | new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL); |
537f7ccb EB |
3281 | if (!new_ns) { |
3282 | dec_mnt_namespaces(ucounts); | |
cf8d2c11 | 3283 | return ERR_PTR(-ENOMEM); |
537f7ccb | 3284 | } |
74e83122 AV |
3285 | if (!anon) { |
3286 | ret = ns_alloc_inum(&new_ns->ns); | |
3287 | if (ret) { | |
3288 | kfree(new_ns); | |
3289 | dec_mnt_namespaces(ucounts); | |
3290 | return ERR_PTR(ret); | |
3291 | } | |
98f842e6 | 3292 | } |
33c42940 | 3293 | new_ns->ns.ops = &mntns_operations; |
74e83122 AV |
3294 | if (!anon) |
3295 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); | |
1a7b8969 | 3296 | refcount_set(&new_ns->ns.count, 1); |
cf8d2c11 TM |
3297 | INIT_LIST_HEAD(&new_ns->list); |
3298 | init_waitqueue_head(&new_ns->poll); | |
9f6c61f9 | 3299 | spin_lock_init(&new_ns->ns_lock); |
771b1371 | 3300 | new_ns->user_ns = get_user_ns(user_ns); |
537f7ccb | 3301 | new_ns->ucounts = ucounts; |
cf8d2c11 TM |
3302 | return new_ns; |
3303 | } | |
3304 | ||
0766f788 | 3305 | __latent_entropy |
9559f689 AV |
3306 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
3307 | struct user_namespace *user_ns, struct fs_struct *new_fs) | |
1da177e4 | 3308 | { |
6b3286ed | 3309 | struct mnt_namespace *new_ns; |
7f2da1e7 | 3310 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 3311 | struct mount *p, *q; |
9559f689 | 3312 | struct mount *old; |
cb338d06 | 3313 | struct mount *new; |
7a472ef4 | 3314 | int copy_flags; |
1da177e4 | 3315 | |
9559f689 AV |
3316 | BUG_ON(!ns); |
3317 | ||
3318 | if (likely(!(flags & CLONE_NEWNS))) { | |
3319 | get_mnt_ns(ns); | |
3320 | return ns; | |
3321 | } | |
3322 | ||
3323 | old = ns->root; | |
3324 | ||
74e83122 | 3325 | new_ns = alloc_mnt_ns(user_ns, false); |
cf8d2c11 TM |
3326 | if (IS_ERR(new_ns)) |
3327 | return new_ns; | |
1da177e4 | 3328 | |
97216be0 | 3329 | namespace_lock(); |
1da177e4 | 3330 | /* First pass: copy the tree topology */ |
4ce5d2b1 | 3331 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
9559f689 | 3332 | if (user_ns != ns->user_ns) |
3bd045cc | 3333 | copy_flags |= CL_SHARED_TO_SLAVE; |
7a472ef4 | 3334 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
be34d1a3 | 3335 | if (IS_ERR(new)) { |
328e6d90 | 3336 | namespace_unlock(); |
771b1371 | 3337 | free_mnt_ns(new_ns); |
be34d1a3 | 3338 | return ERR_CAST(new); |
1da177e4 | 3339 | } |
3bd045cc AV |
3340 | if (user_ns != ns->user_ns) { |
3341 | lock_mount_hash(); | |
3342 | lock_mnt_tree(new); | |
3343 | unlock_mount_hash(); | |
3344 | } | |
be08d6d2 | 3345 | new_ns->root = new; |
1a4eeaf2 | 3346 | list_add_tail(&new_ns->list, &new->mnt_list); |
1da177e4 LT |
3347 | |
3348 | /* | |
3349 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
3350 | * as belonging to new namespace. We have already acquired a private | |
3351 | * fs_struct, so tsk->fs->lock is not needed. | |
3352 | */ | |
909b0a88 | 3353 | p = old; |
cb338d06 | 3354 | q = new; |
1da177e4 | 3355 | while (p) { |
143c8c91 | 3356 | q->mnt_ns = new_ns; |
d2921684 | 3357 | new_ns->mounts++; |
9559f689 AV |
3358 | if (new_fs) { |
3359 | if (&p->mnt == new_fs->root.mnt) { | |
3360 | new_fs->root.mnt = mntget(&q->mnt); | |
315fc83e | 3361 | rootmnt = &p->mnt; |
1da177e4 | 3362 | } |
9559f689 AV |
3363 | if (&p->mnt == new_fs->pwd.mnt) { |
3364 | new_fs->pwd.mnt = mntget(&q->mnt); | |
315fc83e | 3365 | pwdmnt = &p->mnt; |
1da177e4 | 3366 | } |
1da177e4 | 3367 | } |
909b0a88 AV |
3368 | p = next_mnt(p, old); |
3369 | q = next_mnt(q, new); | |
4ce5d2b1 EB |
3370 | if (!q) |
3371 | break; | |
3372 | while (p->mnt.mnt_root != q->mnt.mnt_root) | |
3373 | p = next_mnt(p, old); | |
1da177e4 | 3374 | } |
328e6d90 | 3375 | namespace_unlock(); |
1da177e4 | 3376 | |
1da177e4 | 3377 | if (rootmnt) |
f03c6599 | 3378 | mntput(rootmnt); |
1da177e4 | 3379 | if (pwdmnt) |
f03c6599 | 3380 | mntput(pwdmnt); |
1da177e4 | 3381 | |
741a2951 | 3382 | return new_ns; |
1da177e4 LT |
3383 | } |
3384 | ||
74e83122 | 3385 | struct dentry *mount_subtree(struct vfsmount *m, const char *name) |
ea441d11 | 3386 | { |
74e83122 | 3387 | struct mount *mnt = real_mount(m); |
ea441d11 | 3388 | struct mnt_namespace *ns; |
d31da0f0 | 3389 | struct super_block *s; |
ea441d11 AV |
3390 | struct path path; |
3391 | int err; | |
3392 | ||
74e83122 AV |
3393 | ns = alloc_mnt_ns(&init_user_ns, true); |
3394 | if (IS_ERR(ns)) { | |
3395 | mntput(m); | |
ea441d11 | 3396 | return ERR_CAST(ns); |
74e83122 AV |
3397 | } |
3398 | mnt->mnt_ns = ns; | |
3399 | ns->root = mnt; | |
3400 | ns->mounts++; | |
3401 | list_add(&mnt->mnt_list, &ns->list); | |
ea441d11 | 3402 | |
74e83122 | 3403 | err = vfs_path_lookup(m->mnt_root, m, |
ea441d11 AV |
3404 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
3405 | ||
3406 | put_mnt_ns(ns); | |
3407 | ||
3408 | if (err) | |
3409 | return ERR_PTR(err); | |
3410 | ||
3411 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
3412 | s = path.mnt->mnt_sb; |
3413 | atomic_inc(&s->s_active); | |
ea441d11 AV |
3414 | mntput(path.mnt); |
3415 | /* lock the sucker */ | |
d31da0f0 | 3416 | down_write(&s->s_umount); |
ea441d11 AV |
3417 | /* ... and return the root of (sub)tree on it */ |
3418 | return path.dentry; | |
3419 | } | |
3420 | EXPORT_SYMBOL(mount_subtree); | |
3421 | ||
cccaa5e3 DB |
3422 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
3423 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 3424 | { |
eca6f534 VN |
3425 | int ret; |
3426 | char *kernel_type; | |
eca6f534 | 3427 | char *kernel_dev; |
b40ef869 | 3428 | void *options; |
1da177e4 | 3429 | |
b8850d1f TG |
3430 | kernel_type = copy_mount_string(type); |
3431 | ret = PTR_ERR(kernel_type); | |
3432 | if (IS_ERR(kernel_type)) | |
eca6f534 | 3433 | goto out_type; |
1da177e4 | 3434 | |
b8850d1f TG |
3435 | kernel_dev = copy_mount_string(dev_name); |
3436 | ret = PTR_ERR(kernel_dev); | |
3437 | if (IS_ERR(kernel_dev)) | |
eca6f534 | 3438 | goto out_dev; |
1da177e4 | 3439 | |
b40ef869 AV |
3440 | options = copy_mount_options(data); |
3441 | ret = PTR_ERR(options); | |
3442 | if (IS_ERR(options)) | |
eca6f534 | 3443 | goto out_data; |
1da177e4 | 3444 | |
b40ef869 | 3445 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
1da177e4 | 3446 | |
b40ef869 | 3447 | kfree(options); |
eca6f534 VN |
3448 | out_data: |
3449 | kfree(kernel_dev); | |
3450 | out_dev: | |
eca6f534 VN |
3451 | kfree(kernel_type); |
3452 | out_type: | |
3453 | return ret; | |
1da177e4 LT |
3454 | } |
3455 | ||
2db154b3 | 3456 | /* |
93766fbd DH |
3457 | * Create a kernel mount representation for a new, prepared superblock |
3458 | * (specified by fs_fd) and attach to an open_tree-like file descriptor. | |
3459 | */ | |
3460 | SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, | |
3461 | unsigned int, attr_flags) | |
3462 | { | |
3463 | struct mnt_namespace *ns; | |
3464 | struct fs_context *fc; | |
3465 | struct file *file; | |
3466 | struct path newmount; | |
3467 | struct mount *mnt; | |
3468 | struct fd f; | |
3469 | unsigned int mnt_flags = 0; | |
3470 | long ret; | |
3471 | ||
3472 | if (!may_mount()) | |
3473 | return -EPERM; | |
3474 | ||
3475 | if ((flags & ~(FSMOUNT_CLOEXEC)) != 0) | |
3476 | return -EINVAL; | |
3477 | ||
3478 | if (attr_flags & ~(MOUNT_ATTR_RDONLY | | |
3479 | MOUNT_ATTR_NOSUID | | |
3480 | MOUNT_ATTR_NODEV | | |
3481 | MOUNT_ATTR_NOEXEC | | |
3482 | MOUNT_ATTR__ATIME | | |
3483 | MOUNT_ATTR_NODIRATIME)) | |
3484 | return -EINVAL; | |
3485 | ||
3486 | if (attr_flags & MOUNT_ATTR_RDONLY) | |
3487 | mnt_flags |= MNT_READONLY; | |
3488 | if (attr_flags & MOUNT_ATTR_NOSUID) | |
3489 | mnt_flags |= MNT_NOSUID; | |
3490 | if (attr_flags & MOUNT_ATTR_NODEV) | |
3491 | mnt_flags |= MNT_NODEV; | |
3492 | if (attr_flags & MOUNT_ATTR_NOEXEC) | |
3493 | mnt_flags |= MNT_NOEXEC; | |
3494 | if (attr_flags & MOUNT_ATTR_NODIRATIME) | |
3495 | mnt_flags |= MNT_NODIRATIME; | |
3496 | ||
3497 | switch (attr_flags & MOUNT_ATTR__ATIME) { | |
3498 | case MOUNT_ATTR_STRICTATIME: | |
3499 | break; | |
3500 | case MOUNT_ATTR_NOATIME: | |
3501 | mnt_flags |= MNT_NOATIME; | |
3502 | break; | |
3503 | case MOUNT_ATTR_RELATIME: | |
3504 | mnt_flags |= MNT_RELATIME; | |
3505 | break; | |
3506 | default: | |
3507 | return -EINVAL; | |
3508 | } | |
3509 | ||
3510 | f = fdget(fs_fd); | |
3511 | if (!f.file) | |
3512 | return -EBADF; | |
3513 | ||
3514 | ret = -EINVAL; | |
3515 | if (f.file->f_op != &fscontext_fops) | |
3516 | goto err_fsfd; | |
3517 | ||
3518 | fc = f.file->private_data; | |
3519 | ||
3520 | ret = mutex_lock_interruptible(&fc->uapi_mutex); | |
3521 | if (ret < 0) | |
3522 | goto err_fsfd; | |
3523 | ||
3524 | /* There must be a valid superblock or we can't mount it */ | |
3525 | ret = -EINVAL; | |
3526 | if (!fc->root) | |
3527 | goto err_unlock; | |
3528 | ||
3529 | ret = -EPERM; | |
3530 | if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { | |
3531 | pr_warn("VFS: Mount too revealing\n"); | |
3532 | goto err_unlock; | |
3533 | } | |
3534 | ||
3535 | ret = -EBUSY; | |
3536 | if (fc->phase != FS_CONTEXT_AWAITING_MOUNT) | |
3537 | goto err_unlock; | |
3538 | ||
3539 | ret = -EPERM; | |
3540 | if ((fc->sb_flags & SB_MANDLOCK) && !may_mandlock()) | |
3541 | goto err_unlock; | |
3542 | ||
3543 | newmount.mnt = vfs_create_mount(fc); | |
3544 | if (IS_ERR(newmount.mnt)) { | |
3545 | ret = PTR_ERR(newmount.mnt); | |
3546 | goto err_unlock; | |
3547 | } | |
3548 | newmount.dentry = dget(fc->root); | |
3549 | newmount.mnt->mnt_flags = mnt_flags; | |
3550 | ||
3551 | /* We've done the mount bit - now move the file context into more or | |
3552 | * less the same state as if we'd done an fspick(). We don't want to | |
3553 | * do any memory allocation or anything like that at this point as we | |
3554 | * don't want to have to handle any errors incurred. | |
3555 | */ | |
3556 | vfs_clean_context(fc); | |
3557 | ||
3558 | ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true); | |
3559 | if (IS_ERR(ns)) { | |
3560 | ret = PTR_ERR(ns); | |
3561 | goto err_path; | |
3562 | } | |
3563 | mnt = real_mount(newmount.mnt); | |
3564 | mnt->mnt_ns = ns; | |
3565 | ns->root = mnt; | |
3566 | ns->mounts = 1; | |
3567 | list_add(&mnt->mnt_list, &ns->list); | |
1b0b9cc8 | 3568 | mntget(newmount.mnt); |
93766fbd DH |
3569 | |
3570 | /* Attach to an apparent O_PATH fd with a note that we need to unmount | |
3571 | * it, not just simply put it. | |
3572 | */ | |
3573 | file = dentry_open(&newmount, O_PATH, fc->cred); | |
3574 | if (IS_ERR(file)) { | |
3575 | dissolve_on_fput(newmount.mnt); | |
3576 | ret = PTR_ERR(file); | |
3577 | goto err_path; | |
3578 | } | |
3579 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
3580 | ||
3581 | ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0); | |
3582 | if (ret >= 0) | |
3583 | fd_install(ret, file); | |
3584 | else | |
3585 | fput(file); | |
3586 | ||
3587 | err_path: | |
3588 | path_put(&newmount); | |
3589 | err_unlock: | |
3590 | mutex_unlock(&fc->uapi_mutex); | |
3591 | err_fsfd: | |
3592 | fdput(f); | |
3593 | return ret; | |
3594 | } | |
3595 | ||
3596 | /* | |
3597 | * Move a mount from one place to another. In combination with | |
3598 | * fsopen()/fsmount() this is used to install a new mount and in combination | |
3599 | * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy | |
3600 | * a mount subtree. | |
2db154b3 DH |
3601 | * |
3602 | * Note the flags value is a combination of MOVE_MOUNT_* flags. | |
3603 | */ | |
3604 | SYSCALL_DEFINE5(move_mount, | |
2658ce09 BD |
3605 | int, from_dfd, const char __user *, from_pathname, |
3606 | int, to_dfd, const char __user *, to_pathname, | |
2db154b3 DH |
3607 | unsigned int, flags) |
3608 | { | |
3609 | struct path from_path, to_path; | |
3610 | unsigned int lflags; | |
3611 | int ret = 0; | |
3612 | ||
3613 | if (!may_mount()) | |
3614 | return -EPERM; | |
3615 | ||
3616 | if (flags & ~MOVE_MOUNT__MASK) | |
3617 | return -EINVAL; | |
3618 | ||
3619 | /* If someone gives a pathname, they aren't permitted to move | |
3620 | * from an fd that requires unmount as we can't get at the flag | |
3621 | * to clear it afterwards. | |
3622 | */ | |
3623 | lflags = 0; | |
3624 | if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3625 | if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3626 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3627 | ||
3628 | ret = user_path_at(from_dfd, from_pathname, lflags, &from_path); | |
3629 | if (ret < 0) | |
3630 | return ret; | |
3631 | ||
3632 | lflags = 0; | |
3633 | if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3634 | if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3635 | if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3636 | ||
3637 | ret = user_path_at(to_dfd, to_pathname, lflags, &to_path); | |
3638 | if (ret < 0) | |
3639 | goto out_from; | |
3640 | ||
3641 | ret = security_move_mount(&from_path, &to_path); | |
3642 | if (ret < 0) | |
3643 | goto out_to; | |
3644 | ||
3645 | ret = do_move_mount(&from_path, &to_path); | |
3646 | ||
3647 | out_to: | |
3648 | path_put(&to_path); | |
3649 | out_from: | |
3650 | path_put(&from_path); | |
3651 | return ret; | |
3652 | } | |
3653 | ||
afac7cba AV |
3654 | /* |
3655 | * Return true if path is reachable from root | |
3656 | * | |
48a066e7 | 3657 | * namespace_sem or mount_lock is held |
afac7cba | 3658 | */ |
643822b4 | 3659 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
3660 | const struct path *root) |
3661 | { | |
643822b4 | 3662 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 3663 | dentry = mnt->mnt_mountpoint; |
0714a533 | 3664 | mnt = mnt->mnt_parent; |
afac7cba | 3665 | } |
643822b4 | 3666 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
3667 | } |
3668 | ||
640eb7e7 | 3669 | bool path_is_under(const struct path *path1, const struct path *path2) |
afac7cba | 3670 | { |
25ab4c9b | 3671 | bool res; |
48a066e7 | 3672 | read_seqlock_excl(&mount_lock); |
643822b4 | 3673 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
48a066e7 | 3674 | read_sequnlock_excl(&mount_lock); |
afac7cba AV |
3675 | return res; |
3676 | } | |
3677 | EXPORT_SYMBOL(path_is_under); | |
3678 | ||
1da177e4 LT |
3679 | /* |
3680 | * pivot_root Semantics: | |
3681 | * Moves the root file system of the current process to the directory put_old, | |
3682 | * makes new_root as the new root file system of the current process, and sets | |
3683 | * root/cwd of all processes which had them on the current root to new_root. | |
3684 | * | |
3685 | * Restrictions: | |
3686 | * The new_root and put_old must be directories, and must not be on the | |
3687 | * same file system as the current process root. The put_old must be | |
3688 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
3689 | * pointed to by put_old must yield the same directory as new_root. No other | |
3690 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
3691 | * | |
4a0d11fa | 3692 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
0c1bc6b8 | 3693 | * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives |
4a0d11fa NB |
3694 | * in this situation. |
3695 | * | |
1da177e4 LT |
3696 | * Notes: |
3697 | * - we don't move root/cwd if they are not at the root (reason: if something | |
3698 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
3699 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
3700 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
3701 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
3702 | * first. | |
3703 | */ | |
3480b257 HC |
3704 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
3705 | const char __user *, put_old) | |
1da177e4 | 3706 | { |
2763d119 AV |
3707 | struct path new, old, root; |
3708 | struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; | |
84d17192 | 3709 | struct mountpoint *old_mp, *root_mp; |
1da177e4 LT |
3710 | int error; |
3711 | ||
9b40bc90 | 3712 | if (!may_mount()) |
1da177e4 LT |
3713 | return -EPERM; |
3714 | ||
ce6595a2 AV |
3715 | error = user_path_at(AT_FDCWD, new_root, |
3716 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new); | |
1da177e4 LT |
3717 | if (error) |
3718 | goto out0; | |
1da177e4 | 3719 | |
ce6595a2 AV |
3720 | error = user_path_at(AT_FDCWD, put_old, |
3721 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old); | |
1da177e4 LT |
3722 | if (error) |
3723 | goto out1; | |
3724 | ||
2d8f3038 | 3725 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
3726 | if (error) |
3727 | goto out2; | |
1da177e4 | 3728 | |
f7ad3c6b | 3729 | get_fs_root(current->fs, &root); |
84d17192 AV |
3730 | old_mp = lock_mount(&old); |
3731 | error = PTR_ERR(old_mp); | |
3732 | if (IS_ERR(old_mp)) | |
b12cea91 AV |
3733 | goto out3; |
3734 | ||
1da177e4 | 3735 | error = -EINVAL; |
419148da AV |
3736 | new_mnt = real_mount(new.mnt); |
3737 | root_mnt = real_mount(root.mnt); | |
84d17192 | 3738 | old_mnt = real_mount(old.mnt); |
2763d119 AV |
3739 | ex_parent = new_mnt->mnt_parent; |
3740 | root_parent = root_mnt->mnt_parent; | |
84d17192 | 3741 | if (IS_MNT_SHARED(old_mnt) || |
2763d119 AV |
3742 | IS_MNT_SHARED(ex_parent) || |
3743 | IS_MNT_SHARED(root_parent)) | |
b12cea91 | 3744 | goto out4; |
143c8c91 | 3745 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
b12cea91 | 3746 | goto out4; |
5ff9d8a6 EB |
3747 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
3748 | goto out4; | |
1da177e4 | 3749 | error = -ENOENT; |
f3da392e | 3750 | if (d_unlinked(new.dentry)) |
b12cea91 | 3751 | goto out4; |
1da177e4 | 3752 | error = -EBUSY; |
84d17192 | 3753 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
b12cea91 | 3754 | goto out4; /* loop, on the same file system */ |
1da177e4 | 3755 | error = -EINVAL; |
8c3ee42e | 3756 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 3757 | goto out4; /* not a mountpoint */ |
676da58d | 3758 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 3759 | goto out4; /* not attached */ |
2d8f3038 | 3760 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 3761 | goto out4; /* not a mountpoint */ |
676da58d | 3762 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 3763 | goto out4; /* not attached */ |
4ac91378 | 3764 | /* make sure we can reach put_old from new_root */ |
84d17192 | 3765 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
b12cea91 | 3766 | goto out4; |
0d082601 EB |
3767 | /* make certain new is below the root */ |
3768 | if (!is_path_reachable(new_mnt, new.dentry, &root)) | |
3769 | goto out4; | |
719ea2fb | 3770 | lock_mount_hash(); |
2763d119 AV |
3771 | umount_mnt(new_mnt); |
3772 | root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ | |
5ff9d8a6 EB |
3773 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
3774 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; | |
3775 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
3776 | } | |
4ac91378 | 3777 | /* mount old root on put_old */ |
84d17192 | 3778 | attach_mnt(root_mnt, old_mnt, old_mp); |
4ac91378 | 3779 | /* mount new_root on / */ |
2763d119 AV |
3780 | attach_mnt(new_mnt, root_parent, root_mp); |
3781 | mnt_add_count(root_parent, -1); | |
6b3286ed | 3782 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
4fed655c EB |
3783 | /* A moved mount should not expire automatically */ |
3784 | list_del_init(&new_mnt->mnt_expire); | |
3895dbf8 | 3785 | put_mountpoint(root_mp); |
719ea2fb | 3786 | unlock_mount_hash(); |
2d8f3038 | 3787 | chroot_fs_refs(&root, &new); |
1da177e4 | 3788 | error = 0; |
b12cea91 | 3789 | out4: |
84d17192 | 3790 | unlock_mount(old_mp); |
2763d119 AV |
3791 | if (!error) |
3792 | mntput_no_expire(ex_parent); | |
b12cea91 | 3793 | out3: |
8c3ee42e | 3794 | path_put(&root); |
b12cea91 | 3795 | out2: |
2d8f3038 | 3796 | path_put(&old); |
1da177e4 | 3797 | out1: |
2d8f3038 | 3798 | path_put(&new); |
1da177e4 | 3799 | out0: |
1da177e4 | 3800 | return error; |
1da177e4 LT |
3801 | } |
3802 | ||
3803 | static void __init init_mount_tree(void) | |
3804 | { | |
3805 | struct vfsmount *mnt; | |
74e83122 | 3806 | struct mount *m; |
6b3286ed | 3807 | struct mnt_namespace *ns; |
ac748a09 | 3808 | struct path root; |
1da177e4 | 3809 | |
fd3e007f | 3810 | mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL); |
1da177e4 LT |
3811 | if (IS_ERR(mnt)) |
3812 | panic("Can't create rootfs"); | |
b3e19d92 | 3813 | |
74e83122 | 3814 | ns = alloc_mnt_ns(&init_user_ns, false); |
3b22edc5 | 3815 | if (IS_ERR(ns)) |
1da177e4 | 3816 | panic("Can't allocate initial namespace"); |
74e83122 AV |
3817 | m = real_mount(mnt); |
3818 | m->mnt_ns = ns; | |
3819 | ns->root = m; | |
3820 | ns->mounts = 1; | |
3821 | list_add(&m->mnt_list, &ns->list); | |
6b3286ed KK |
3822 | init_task.nsproxy->mnt_ns = ns; |
3823 | get_mnt_ns(ns); | |
3824 | ||
be08d6d2 AV |
3825 | root.mnt = mnt; |
3826 | root.dentry = mnt->mnt_root; | |
da362b09 | 3827 | mnt->mnt_flags |= MNT_LOCKED; |
ac748a09 JB |
3828 | |
3829 | set_fs_pwd(current->fs, &root); | |
3830 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
3831 | } |
3832 | ||
74bf17cf | 3833 | void __init mnt_init(void) |
1da177e4 | 3834 | { |
15a67dd8 | 3835 | int err; |
1da177e4 | 3836 | |
7d6fec45 | 3837 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
20c2df83 | 3838 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 3839 | |
0818bf27 | 3840 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
38129a13 | 3841 | sizeof(struct hlist_head), |
0818bf27 | 3842 | mhash_entries, 19, |
3d375d78 | 3843 | HASH_ZERO, |
0818bf27 AV |
3844 | &m_hash_shift, &m_hash_mask, 0, 0); |
3845 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", | |
3846 | sizeof(struct hlist_head), | |
3847 | mphash_entries, 19, | |
3d375d78 | 3848 | HASH_ZERO, |
0818bf27 | 3849 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
1da177e4 | 3850 | |
84d17192 | 3851 | if (!mount_hashtable || !mountpoint_hashtable) |
1da177e4 LT |
3852 | panic("Failed to allocate mount hash table\n"); |
3853 | ||
4b93dc9b TH |
3854 | kernfs_init(); |
3855 | ||
15a67dd8 RD |
3856 | err = sysfs_init(); |
3857 | if (err) | |
3858 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 3859 | __func__, err); |
00d26666 GKH |
3860 | fs_kobj = kobject_create_and_add("fs", NULL); |
3861 | if (!fs_kobj) | |
8e24eea7 | 3862 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
037f11b4 | 3863 | shmem_init(); |
1da177e4 LT |
3864 | init_rootfs(); |
3865 | init_mount_tree(); | |
3866 | } | |
3867 | ||
616511d0 | 3868 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 3869 | { |
1a7b8969 | 3870 | if (!refcount_dec_and_test(&ns->ns.count)) |
616511d0 | 3871 | return; |
7b00ed6f | 3872 | drop_collected_mounts(&ns->root->mnt); |
771b1371 | 3873 | free_mnt_ns(ns); |
1da177e4 | 3874 | } |
9d412a43 | 3875 | |
d911b458 | 3876 | struct vfsmount *kern_mount(struct file_system_type *type) |
9d412a43 | 3877 | { |
423e0ab0 | 3878 | struct vfsmount *mnt; |
d911b458 | 3879 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
423e0ab0 TC |
3880 | if (!IS_ERR(mnt)) { |
3881 | /* | |
3882 | * it is a longterm mount, don't release mnt until | |
3883 | * we unmount before file sys is unregistered | |
3884 | */ | |
f7a99c5b | 3885 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
423e0ab0 TC |
3886 | } |
3887 | return mnt; | |
9d412a43 | 3888 | } |
d911b458 | 3889 | EXPORT_SYMBOL_GPL(kern_mount); |
423e0ab0 TC |
3890 | |
3891 | void kern_unmount(struct vfsmount *mnt) | |
3892 | { | |
3893 | /* release long term mount so mount point can be released */ | |
3894 | if (!IS_ERR_OR_NULL(mnt)) { | |
f7a99c5b | 3895 | real_mount(mnt)->mnt_ns = NULL; |
48a066e7 | 3896 | synchronize_rcu(); /* yecchhh... */ |
423e0ab0 TC |
3897 | mntput(mnt); |
3898 | } | |
3899 | } | |
3900 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 | 3901 | |
df820f8d MS |
3902 | void kern_unmount_array(struct vfsmount *mnt[], unsigned int num) |
3903 | { | |
3904 | unsigned int i; | |
3905 | ||
3906 | for (i = 0; i < num; i++) | |
3907 | if (mnt[i]) | |
3908 | real_mount(mnt[i])->mnt_ns = NULL; | |
3909 | synchronize_rcu_expedited(); | |
3910 | for (i = 0; i < num; i++) | |
3911 | mntput(mnt[i]); | |
3912 | } | |
3913 | EXPORT_SYMBOL(kern_unmount_array); | |
3914 | ||
02125a82 AV |
3915 | bool our_mnt(struct vfsmount *mnt) |
3916 | { | |
143c8c91 | 3917 | return check_mnt(real_mount(mnt)); |
02125a82 | 3918 | } |
8823c079 | 3919 | |
3151527e EB |
3920 | bool current_chrooted(void) |
3921 | { | |
3922 | /* Does the current process have a non-standard root */ | |
3923 | struct path ns_root; | |
3924 | struct path fs_root; | |
3925 | bool chrooted; | |
3926 | ||
3927 | /* Find the namespace root */ | |
3928 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; | |
3929 | ns_root.dentry = ns_root.mnt->mnt_root; | |
3930 | path_get(&ns_root); | |
3931 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) | |
3932 | ; | |
3933 | ||
3934 | get_fs_root(current->fs, &fs_root); | |
3935 | ||
3936 | chrooted = !path_equal(&fs_root, &ns_root); | |
3937 | ||
3938 | path_put(&fs_root); | |
3939 | path_put(&ns_root); | |
3940 | ||
3941 | return chrooted; | |
3942 | } | |
3943 | ||
132e4608 DH |
3944 | static bool mnt_already_visible(struct mnt_namespace *ns, |
3945 | const struct super_block *sb, | |
8654df4e | 3946 | int *new_mnt_flags) |
87a8ebd6 | 3947 | { |
8c6cf9cc | 3948 | int new_flags = *new_mnt_flags; |
87a8ebd6 | 3949 | struct mount *mnt; |
e51db735 | 3950 | bool visible = false; |
87a8ebd6 | 3951 | |
44bb4385 | 3952 | down_read(&namespace_sem); |
9f6c61f9 | 3953 | lock_ns_list(ns); |
87a8ebd6 | 3954 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
e51db735 | 3955 | struct mount *child; |
77b1a97d EB |
3956 | int mnt_flags; |
3957 | ||
9f6c61f9 MS |
3958 | if (mnt_is_cursor(mnt)) |
3959 | continue; | |
3960 | ||
132e4608 | 3961 | if (mnt->mnt.mnt_sb->s_type != sb->s_type) |
e51db735 EB |
3962 | continue; |
3963 | ||
7e96c1b0 EB |
3964 | /* This mount is not fully visible if it's root directory |
3965 | * is not the root directory of the filesystem. | |
3966 | */ | |
3967 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) | |
3968 | continue; | |
3969 | ||
a1935c17 | 3970 | /* A local view of the mount flags */ |
77b1a97d | 3971 | mnt_flags = mnt->mnt.mnt_flags; |
77b1a97d | 3972 | |
695e9df0 | 3973 | /* Don't miss readonly hidden in the superblock flags */ |
bc98a42c | 3974 | if (sb_rdonly(mnt->mnt.mnt_sb)) |
695e9df0 EB |
3975 | mnt_flags |= MNT_LOCK_READONLY; |
3976 | ||
8c6cf9cc EB |
3977 | /* Verify the mount flags are equal to or more permissive |
3978 | * than the proposed new mount. | |
3979 | */ | |
77b1a97d | 3980 | if ((mnt_flags & MNT_LOCK_READONLY) && |
8c6cf9cc EB |
3981 | !(new_flags & MNT_READONLY)) |
3982 | continue; | |
77b1a97d EB |
3983 | if ((mnt_flags & MNT_LOCK_ATIME) && |
3984 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) | |
8c6cf9cc EB |
3985 | continue; |
3986 | ||
ceeb0e5d EB |
3987 | /* This mount is not fully visible if there are any |
3988 | * locked child mounts that cover anything except for | |
3989 | * empty directories. | |
e51db735 EB |
3990 | */ |
3991 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
3992 | struct inode *inode = child->mnt_mountpoint->d_inode; | |
ceeb0e5d | 3993 | /* Only worry about locked mounts */ |
d71ed6c9 | 3994 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
ceeb0e5d | 3995 | continue; |
7236c85e EB |
3996 | /* Is the directory permanetly empty? */ |
3997 | if (!is_empty_dir_inode(inode)) | |
e51db735 | 3998 | goto next; |
87a8ebd6 | 3999 | } |
8c6cf9cc | 4000 | /* Preserve the locked attributes */ |
77b1a97d | 4001 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
77b1a97d | 4002 | MNT_LOCK_ATIME); |
e51db735 EB |
4003 | visible = true; |
4004 | goto found; | |
4005 | next: ; | |
87a8ebd6 | 4006 | } |
e51db735 | 4007 | found: |
9f6c61f9 | 4008 | unlock_ns_list(ns); |
44bb4385 | 4009 | up_read(&namespace_sem); |
e51db735 | 4010 | return visible; |
87a8ebd6 EB |
4011 | } |
4012 | ||
132e4608 | 4013 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags) |
8654df4e | 4014 | { |
a1935c17 | 4015 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
8654df4e EB |
4016 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
4017 | unsigned long s_iflags; | |
4018 | ||
4019 | if (ns->user_ns == &init_user_ns) | |
4020 | return false; | |
4021 | ||
4022 | /* Can this filesystem be too revealing? */ | |
132e4608 | 4023 | s_iflags = sb->s_iflags; |
8654df4e EB |
4024 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
4025 | return false; | |
4026 | ||
a1935c17 EB |
4027 | if ((s_iflags & required_iflags) != required_iflags) { |
4028 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", | |
4029 | required_iflags); | |
4030 | return true; | |
4031 | } | |
4032 | ||
132e4608 | 4033 | return !mnt_already_visible(ns, sb, new_mnt_flags); |
8654df4e EB |
4034 | } |
4035 | ||
380cf5ba AL |
4036 | bool mnt_may_suid(struct vfsmount *mnt) |
4037 | { | |
4038 | /* | |
4039 | * Foreign mounts (accessed via fchdir or through /proc | |
4040 | * symlinks) are always treated as if they are nosuid. This | |
4041 | * prevents namespaces from trusting potentially unsafe | |
4042 | * suid/sgid bits, file caps, or security labels that originate | |
4043 | * in other namespaces. | |
4044 | */ | |
4045 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && | |
4046 | current_in_userns(mnt->mnt_sb->s_user_ns); | |
4047 | } | |
4048 | ||
64964528 | 4049 | static struct ns_common *mntns_get(struct task_struct *task) |
8823c079 | 4050 | { |
58be2825 | 4051 | struct ns_common *ns = NULL; |
8823c079 EB |
4052 | struct nsproxy *nsproxy; |
4053 | ||
728dba3a EB |
4054 | task_lock(task); |
4055 | nsproxy = task->nsproxy; | |
8823c079 | 4056 | if (nsproxy) { |
58be2825 AV |
4057 | ns = &nsproxy->mnt_ns->ns; |
4058 | get_mnt_ns(to_mnt_ns(ns)); | |
8823c079 | 4059 | } |
728dba3a | 4060 | task_unlock(task); |
8823c079 EB |
4061 | |
4062 | return ns; | |
4063 | } | |
4064 | ||
64964528 | 4065 | static void mntns_put(struct ns_common *ns) |
8823c079 | 4066 | { |
58be2825 | 4067 | put_mnt_ns(to_mnt_ns(ns)); |
8823c079 EB |
4068 | } |
4069 | ||
f2a8d52e | 4070 | static int mntns_install(struct nsset *nsset, struct ns_common *ns) |
8823c079 | 4071 | { |
f2a8d52e CB |
4072 | struct nsproxy *nsproxy = nsset->nsproxy; |
4073 | struct fs_struct *fs = nsset->fs; | |
4f757f3c | 4074 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns; |
f2a8d52e | 4075 | struct user_namespace *user_ns = nsset->cred->user_ns; |
8823c079 | 4076 | struct path root; |
4f757f3c | 4077 | int err; |
8823c079 | 4078 | |
0c55cfc4 | 4079 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
f2a8d52e CB |
4080 | !ns_capable(user_ns, CAP_SYS_CHROOT) || |
4081 | !ns_capable(user_ns, CAP_SYS_ADMIN)) | |
ae11e0f1 | 4082 | return -EPERM; |
8823c079 | 4083 | |
74e83122 AV |
4084 | if (is_anon_ns(mnt_ns)) |
4085 | return -EINVAL; | |
4086 | ||
8823c079 EB |
4087 | if (fs->users != 1) |
4088 | return -EINVAL; | |
4089 | ||
4090 | get_mnt_ns(mnt_ns); | |
4f757f3c | 4091 | old_mnt_ns = nsproxy->mnt_ns; |
8823c079 EB |
4092 | nsproxy->mnt_ns = mnt_ns; |
4093 | ||
4094 | /* Find the root */ | |
4f757f3c AV |
4095 | err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt, |
4096 | "/", LOOKUP_DOWN, &root); | |
4097 | if (err) { | |
4098 | /* revert to old namespace */ | |
4099 | nsproxy->mnt_ns = old_mnt_ns; | |
4100 | put_mnt_ns(mnt_ns); | |
4101 | return err; | |
4102 | } | |
8823c079 | 4103 | |
4068367c AV |
4104 | put_mnt_ns(old_mnt_ns); |
4105 | ||
8823c079 EB |
4106 | /* Update the pwd and root */ |
4107 | set_fs_pwd(fs, &root); | |
4108 | set_fs_root(fs, &root); | |
4109 | ||
4110 | path_put(&root); | |
4111 | return 0; | |
4112 | } | |
4113 | ||
bcac25a5 AV |
4114 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
4115 | { | |
4116 | return to_mnt_ns(ns)->user_ns; | |
4117 | } | |
4118 | ||
8823c079 EB |
4119 | const struct proc_ns_operations mntns_operations = { |
4120 | .name = "mnt", | |
4121 | .type = CLONE_NEWNS, | |
4122 | .get = mntns_get, | |
4123 | .put = mntns_put, | |
4124 | .install = mntns_install, | |
bcac25a5 | 4125 | .owner = mntns_owner, |
8823c079 | 4126 | }; |