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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> |
9caccd41 | 28 | #include <linux/proc_fs.h> |
9ea459e1 | 29 | #include <linux/task_work.h> |
9164bb4a | 30 | #include <linux/sched/task.h> |
e262e32d | 31 | #include <uapi/linux/mount.h> |
9bc61ab1 | 32 | #include <linux/fs_context.h> |
037f11b4 | 33 | #include <linux/shmem_fs.h> |
bd303368 | 34 | #include <linux/mnt_idmapping.h> |
9164bb4a | 35 | |
07b20889 | 36 | #include "pnode.h" |
948730b0 | 37 | #include "internal.h" |
1da177e4 | 38 | |
d2921684 | 39 | /* Maximum number of mounts in a mount namespace */ |
ab171b95 | 40 | static unsigned int sysctl_mount_max __read_mostly = 100000; |
d2921684 | 41 | |
0818bf27 AV |
42 | static unsigned int m_hash_mask __read_mostly; |
43 | static unsigned int m_hash_shift __read_mostly; | |
44 | static unsigned int mp_hash_mask __read_mostly; | |
45 | static unsigned int mp_hash_shift __read_mostly; | |
46 | ||
47 | static __initdata unsigned long mhash_entries; | |
48 | static int __init set_mhash_entries(char *str) | |
49 | { | |
50 | if (!str) | |
51 | return 0; | |
52 | mhash_entries = simple_strtoul(str, &str, 0); | |
53 | return 1; | |
54 | } | |
55 | __setup("mhash_entries=", set_mhash_entries); | |
56 | ||
57 | static __initdata unsigned long mphash_entries; | |
58 | static int __init set_mphash_entries(char *str) | |
59 | { | |
60 | if (!str) | |
61 | return 0; | |
62 | mphash_entries = simple_strtoul(str, &str, 0); | |
63 | return 1; | |
64 | } | |
65 | __setup("mphash_entries=", set_mphash_entries); | |
13f14b4d | 66 | |
c7999c36 | 67 | static u64 event; |
73cd49ec | 68 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 69 | static DEFINE_IDA(mnt_group_ida); |
1da177e4 | 70 | |
38129a13 | 71 | static struct hlist_head *mount_hashtable __read_mostly; |
0818bf27 | 72 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
e18b890b | 73 | static struct kmem_cache *mnt_cache __read_mostly; |
59aa0da8 | 74 | static DECLARE_RWSEM(namespace_sem); |
4edbe133 AV |
75 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
76 | static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ | |
1da177e4 | 77 | |
256c8aed CB |
78 | struct mnt_idmap { |
79 | struct user_namespace *owner; | |
80 | refcount_t count; | |
81 | }; | |
82 | ||
83 | /* | |
84 | * Carries the initial idmapping of 0:0:4294967295 which is an identity | |
85 | * mapping. This means that {g,u}id 0 is mapped to {g,u}id 0, {g,u}id 1 is | |
86 | * mapped to {g,u}id 1, [...], {g,u}id 1000 to {g,u}id 1000, [...]. | |
87 | */ | |
88 | struct mnt_idmap nop_mnt_idmap = { | |
89 | .owner = &init_user_ns, | |
90 | .count = REFCOUNT_INIT(1), | |
91 | }; | |
92 | EXPORT_SYMBOL_GPL(nop_mnt_idmap); | |
93 | ||
2a186721 CB |
94 | struct mount_kattr { |
95 | unsigned int attr_set; | |
96 | unsigned int attr_clr; | |
97 | unsigned int propagation; | |
98 | unsigned int lookup_flags; | |
99 | bool recurse; | |
9caccd41 | 100 | struct user_namespace *mnt_userns; |
256c8aed | 101 | struct mnt_idmap *mnt_idmap; |
2a186721 CB |
102 | }; |
103 | ||
f87fd4c2 | 104 | /* /sys/fs */ |
00d26666 GKH |
105 | struct kobject *fs_kobj; |
106 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 107 | |
99b7db7b NP |
108 | /* |
109 | * vfsmount lock may be taken for read to prevent changes to the | |
110 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
111 | * up the tree. | |
112 | * | |
113 | * It should be taken for write in all cases where the vfsmount | |
114 | * tree or hash is modified or when a vfsmount structure is modified. | |
115 | */ | |
48a066e7 | 116 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
99b7db7b | 117 | |
d033cb67 CB |
118 | static inline void lock_mount_hash(void) |
119 | { | |
120 | write_seqlock(&mount_lock); | |
121 | } | |
122 | ||
123 | static inline void unlock_mount_hash(void) | |
124 | { | |
125 | write_sequnlock(&mount_lock); | |
126 | } | |
127 | ||
38129a13 | 128 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 129 | { |
b58fed8b RP |
130 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
131 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
0818bf27 AV |
132 | tmp = tmp + (tmp >> m_hash_shift); |
133 | return &mount_hashtable[tmp & m_hash_mask]; | |
134 | } | |
135 | ||
136 | static inline struct hlist_head *mp_hash(struct dentry *dentry) | |
137 | { | |
138 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); | |
139 | tmp = tmp + (tmp >> mp_hash_shift); | |
140 | return &mountpoint_hashtable[tmp & mp_hash_mask]; | |
1da177e4 LT |
141 | } |
142 | ||
b105e270 | 143 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec | 144 | { |
169b480e MW |
145 | int res = ida_alloc(&mnt_id_ida, GFP_KERNEL); |
146 | ||
147 | if (res < 0) | |
148 | return res; | |
149 | mnt->mnt_id = res; | |
150 | return 0; | |
73cd49ec MS |
151 | } |
152 | ||
b105e270 | 153 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 154 | { |
169b480e | 155 | ida_free(&mnt_id_ida, mnt->mnt_id); |
73cd49ec MS |
156 | } |
157 | ||
719f5d7f MS |
158 | /* |
159 | * Allocate a new peer group ID | |
719f5d7f | 160 | */ |
4b8b21f4 | 161 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 162 | { |
169b480e | 163 | int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL); |
f21f6220 | 164 | |
169b480e MW |
165 | if (res < 0) |
166 | return res; | |
167 | mnt->mnt_group_id = res; | |
168 | return 0; | |
719f5d7f MS |
169 | } |
170 | ||
171 | /* | |
172 | * Release a peer group ID | |
173 | */ | |
4b8b21f4 | 174 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 175 | { |
169b480e | 176 | ida_free(&mnt_group_ida, mnt->mnt_group_id); |
15169fe7 | 177 | mnt->mnt_group_id = 0; |
719f5d7f MS |
178 | } |
179 | ||
b3e19d92 NP |
180 | /* |
181 | * vfsmount lock must be held for read | |
182 | */ | |
83adc753 | 183 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
184 | { |
185 | #ifdef CONFIG_SMP | |
68e8a9fe | 186 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
187 | #else |
188 | preempt_disable(); | |
68e8a9fe | 189 | mnt->mnt_count += n; |
b3e19d92 NP |
190 | preempt_enable(); |
191 | #endif | |
192 | } | |
193 | ||
b3e19d92 NP |
194 | /* |
195 | * vfsmount lock must be held for write | |
196 | */ | |
edf7ddbf | 197 | int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
198 | { |
199 | #ifdef CONFIG_SMP | |
edf7ddbf | 200 | int count = 0; |
b3e19d92 NP |
201 | int cpu; |
202 | ||
203 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 204 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
205 | } |
206 | ||
207 | return count; | |
208 | #else | |
68e8a9fe | 209 | return mnt->mnt_count; |
b3e19d92 NP |
210 | #endif |
211 | } | |
212 | ||
256c8aed CB |
213 | /** |
214 | * mnt_idmap_owner - retrieve owner of the mount's idmapping | |
215 | * @idmap: mount idmapping | |
216 | * | |
217 | * This helper will go away once the conversion to use struct mnt_idmap | |
218 | * everywhere has finished at which point the helper will be unexported. | |
219 | * | |
220 | * Only code that needs to perform permission checks based on the owner of the | |
221 | * idmapping will get access to it. All other code will solely rely on | |
222 | * idmappings. This will get us type safety so it's impossible to conflate | |
223 | * filesystems idmappings with mount idmappings. | |
224 | * | |
225 | * Return: The owner of the idmapping. | |
226 | */ | |
227 | struct user_namespace *mnt_idmap_owner(const struct mnt_idmap *idmap) | |
228 | { | |
229 | return idmap->owner; | |
230 | } | |
231 | EXPORT_SYMBOL_GPL(mnt_idmap_owner); | |
232 | ||
233 | /** | |
234 | * mnt_user_ns - retrieve owner of an idmapped mount | |
235 | * @mnt: the relevant vfsmount | |
236 | * | |
237 | * This helper will go away once the conversion to use struct mnt_idmap | |
238 | * everywhere has finished at which point the helper will be unexported. | |
239 | * | |
240 | * Only code that needs to perform permission checks based on the owner of the | |
241 | * idmapping will get access to it. All other code will solely rely on | |
242 | * idmappings. This will get us type safety so it's impossible to conflate | |
243 | * filesystems idmappings with mount idmappings. | |
244 | * | |
245 | * Return: The owner of the idmapped. | |
246 | */ | |
247 | struct user_namespace *mnt_user_ns(const struct vfsmount *mnt) | |
248 | { | |
249 | struct mnt_idmap *idmap = mnt_idmap(mnt); | |
250 | ||
251 | /* Return the actual owner of the filesystem instead of the nop. */ | |
252 | if (idmap == &nop_mnt_idmap && | |
253 | !initial_idmapping(mnt->mnt_sb->s_user_ns)) | |
254 | return mnt->mnt_sb->s_user_ns; | |
255 | return mnt_idmap_owner(idmap); | |
256 | } | |
257 | EXPORT_SYMBOL_GPL(mnt_user_ns); | |
258 | ||
259 | /** | |
260 | * alloc_mnt_idmap - allocate a new idmapping for the mount | |
261 | * @mnt_userns: owning userns of the idmapping | |
262 | * | |
263 | * Allocate a new struct mnt_idmap which carries the idmapping of the mount. | |
264 | * | |
265 | * Return: On success a new idmap, on error an error pointer is returned. | |
266 | */ | |
267 | static struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns) | |
268 | { | |
269 | struct mnt_idmap *idmap; | |
270 | ||
271 | idmap = kzalloc(sizeof(struct mnt_idmap), GFP_KERNEL_ACCOUNT); | |
272 | if (!idmap) | |
273 | return ERR_PTR(-ENOMEM); | |
274 | ||
275 | idmap->owner = get_user_ns(mnt_userns); | |
276 | refcount_set(&idmap->count, 1); | |
277 | return idmap; | |
278 | } | |
279 | ||
280 | /** | |
281 | * mnt_idmap_get - get a reference to an idmapping | |
282 | * @idmap: the idmap to bump the reference on | |
283 | * | |
284 | * If @idmap is not the @nop_mnt_idmap bump the reference count. | |
285 | * | |
286 | * Return: @idmap with reference count bumped if @not_mnt_idmap isn't passed. | |
287 | */ | |
288 | static inline struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap) | |
289 | { | |
290 | if (idmap != &nop_mnt_idmap) | |
291 | refcount_inc(&idmap->count); | |
292 | ||
293 | return idmap; | |
294 | } | |
295 | ||
296 | /** | |
297 | * mnt_idmap_put - put a reference to an idmapping | |
298 | * @idmap: the idmap to put the reference on | |
299 | * | |
300 | * If this is a non-initial idmapping, put the reference count when a mount is | |
301 | * released and free it if we're the last user. | |
302 | */ | |
303 | static inline void mnt_idmap_put(struct mnt_idmap *idmap) | |
304 | { | |
305 | if (idmap != &nop_mnt_idmap && refcount_dec_and_test(&idmap->count)) { | |
306 | put_user_ns(idmap->owner); | |
307 | kfree(idmap); | |
308 | } | |
309 | } | |
310 | ||
b105e270 | 311 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 312 | { |
c63181e6 AV |
313 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
314 | if (mnt) { | |
73cd49ec MS |
315 | int err; |
316 | ||
c63181e6 | 317 | err = mnt_alloc_id(mnt); |
88b38782 LZ |
318 | if (err) |
319 | goto out_free_cache; | |
320 | ||
321 | if (name) { | |
79f6540b VA |
322 | mnt->mnt_devname = kstrdup_const(name, |
323 | GFP_KERNEL_ACCOUNT); | |
c63181e6 | 324 | if (!mnt->mnt_devname) |
88b38782 | 325 | goto out_free_id; |
73cd49ec MS |
326 | } |
327 | ||
b3e19d92 | 328 | #ifdef CONFIG_SMP |
c63181e6 AV |
329 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
330 | if (!mnt->mnt_pcp) | |
b3e19d92 NP |
331 | goto out_free_devname; |
332 | ||
c63181e6 | 333 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
b3e19d92 | 334 | #else |
c63181e6 AV |
335 | mnt->mnt_count = 1; |
336 | mnt->mnt_writers = 0; | |
b3e19d92 NP |
337 | #endif |
338 | ||
38129a13 | 339 | INIT_HLIST_NODE(&mnt->mnt_hash); |
c63181e6 AV |
340 | INIT_LIST_HEAD(&mnt->mnt_child); |
341 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
342 | INIT_LIST_HEAD(&mnt->mnt_list); | |
343 | INIT_LIST_HEAD(&mnt->mnt_expire); | |
344 | INIT_LIST_HEAD(&mnt->mnt_share); | |
345 | INIT_LIST_HEAD(&mnt->mnt_slave_list); | |
346 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
0a5eb7c8 | 347 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
99b19d16 | 348 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
56cbb429 | 349 | INIT_HLIST_HEAD(&mnt->mnt_stuck_children); |
256c8aed | 350 | mnt->mnt.mnt_idmap = &nop_mnt_idmap; |
1da177e4 | 351 | } |
c63181e6 | 352 | return mnt; |
88b38782 | 353 | |
d3ef3d73 NP |
354 | #ifdef CONFIG_SMP |
355 | out_free_devname: | |
fcc139ae | 356 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 357 | #endif |
88b38782 | 358 | out_free_id: |
c63181e6 | 359 | mnt_free_id(mnt); |
88b38782 | 360 | out_free_cache: |
c63181e6 | 361 | kmem_cache_free(mnt_cache, mnt); |
88b38782 | 362 | return NULL; |
1da177e4 LT |
363 | } |
364 | ||
3d733633 DH |
365 | /* |
366 | * Most r/o checks on a fs are for operations that take | |
367 | * discrete amounts of time, like a write() or unlink(). | |
368 | * We must keep track of when those operations start | |
369 | * (for permission checks) and when they end, so that | |
370 | * we can determine when writes are able to occur to | |
371 | * a filesystem. | |
372 | */ | |
373 | /* | |
374 | * __mnt_is_readonly: check whether a mount is read-only | |
375 | * @mnt: the mount to check for its write status | |
376 | * | |
377 | * This shouldn't be used directly ouside of the VFS. | |
378 | * It does not guarantee that the filesystem will stay | |
379 | * r/w, just that it is right *now*. This can not and | |
380 | * should not be used in place of IS_RDONLY(inode). | |
381 | * mnt_want/drop_write() will _keep_ the filesystem | |
382 | * r/w. | |
383 | */ | |
43f5e655 | 384 | bool __mnt_is_readonly(struct vfsmount *mnt) |
3d733633 | 385 | { |
43f5e655 | 386 | return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb); |
3d733633 DH |
387 | } |
388 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
389 | ||
83adc753 | 390 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 NP |
391 | { |
392 | #ifdef CONFIG_SMP | |
68e8a9fe | 393 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 394 | #else |
68e8a9fe | 395 | mnt->mnt_writers++; |
d3ef3d73 NP |
396 | #endif |
397 | } | |
3d733633 | 398 | |
83adc753 | 399 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 400 | { |
d3ef3d73 | 401 | #ifdef CONFIG_SMP |
68e8a9fe | 402 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 403 | #else |
68e8a9fe | 404 | mnt->mnt_writers--; |
d3ef3d73 | 405 | #endif |
3d733633 | 406 | } |
3d733633 | 407 | |
83adc753 | 408 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 409 | { |
d3ef3d73 NP |
410 | #ifdef CONFIG_SMP |
411 | unsigned int count = 0; | |
3d733633 | 412 | int cpu; |
3d733633 DH |
413 | |
414 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 415 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 416 | } |
3d733633 | 417 | |
d3ef3d73 NP |
418 | return count; |
419 | #else | |
420 | return mnt->mnt_writers; | |
421 | #endif | |
3d733633 DH |
422 | } |
423 | ||
4ed5e82f MS |
424 | static int mnt_is_readonly(struct vfsmount *mnt) |
425 | { | |
426 | if (mnt->mnt_sb->s_readonly_remount) | |
427 | return 1; | |
428 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ | |
429 | smp_rmb(); | |
430 | return __mnt_is_readonly(mnt); | |
431 | } | |
432 | ||
8366025e | 433 | /* |
eb04c282 JK |
434 | * Most r/o & frozen checks on a fs are for operations that take discrete |
435 | * amounts of time, like a write() or unlink(). We must keep track of when | |
436 | * those operations start (for permission checks) and when they end, so that we | |
437 | * can determine when writes are able to occur to a filesystem. | |
8366025e DH |
438 | */ |
439 | /** | |
eb04c282 | 440 | * __mnt_want_write - get write access to a mount without freeze protection |
83adc753 | 441 | * @m: the mount on which to take a write |
8366025e | 442 | * |
eb04c282 JK |
443 | * This tells the low-level filesystem that a write is about to be performed to |
444 | * it, and makes sure that writes are allowed (mnt it read-write) before | |
445 | * returning success. This operation does not protect against filesystem being | |
446 | * frozen. When the write operation is finished, __mnt_drop_write() must be | |
447 | * called. This is effectively a refcount. | |
8366025e | 448 | */ |
eb04c282 | 449 | int __mnt_want_write(struct vfsmount *m) |
8366025e | 450 | { |
83adc753 | 451 | struct mount *mnt = real_mount(m); |
3d733633 | 452 | int ret = 0; |
3d733633 | 453 | |
d3ef3d73 | 454 | preempt_disable(); |
c6653a83 | 455 | mnt_inc_writers(mnt); |
d3ef3d73 | 456 | /* |
c6653a83 | 457 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 NP |
458 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
459 | * incremented count after it has set MNT_WRITE_HOLD. | |
460 | */ | |
461 | smp_mb(); | |
0f8821da SAS |
462 | might_lock(&mount_lock.lock); |
463 | while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) { | |
464 | if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { | |
465 | cpu_relax(); | |
466 | } else { | |
467 | /* | |
468 | * This prevents priority inversion, if the task | |
469 | * setting MNT_WRITE_HOLD got preempted on a remote | |
470 | * CPU, and it prevents life lock if the task setting | |
471 | * MNT_WRITE_HOLD has a lower priority and is bound to | |
472 | * the same CPU as the task that is spinning here. | |
473 | */ | |
474 | preempt_enable(); | |
475 | lock_mount_hash(); | |
476 | unlock_mount_hash(); | |
477 | preempt_disable(); | |
478 | } | |
479 | } | |
d3ef3d73 NP |
480 | /* |
481 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
482 | * be set to match its requirements. So we must not load that until | |
483 | * MNT_WRITE_HOLD is cleared. | |
484 | */ | |
485 | smp_rmb(); | |
4ed5e82f | 486 | if (mnt_is_readonly(m)) { |
c6653a83 | 487 | mnt_dec_writers(mnt); |
3d733633 | 488 | ret = -EROFS; |
3d733633 | 489 | } |
d3ef3d73 | 490 | preempt_enable(); |
eb04c282 JK |
491 | |
492 | return ret; | |
493 | } | |
494 | ||
495 | /** | |
496 | * mnt_want_write - get write access to a mount | |
497 | * @m: the mount on which to take a write | |
498 | * | |
499 | * This tells the low-level filesystem that a write is about to be performed to | |
500 | * it, and makes sure that writes are allowed (mount is read-write, filesystem | |
501 | * is not frozen) before returning success. When the write operation is | |
502 | * finished, mnt_drop_write() must be called. This is effectively a refcount. | |
503 | */ | |
504 | int mnt_want_write(struct vfsmount *m) | |
505 | { | |
506 | int ret; | |
507 | ||
508 | sb_start_write(m->mnt_sb); | |
509 | ret = __mnt_want_write(m); | |
510 | if (ret) | |
511 | sb_end_write(m->mnt_sb); | |
3d733633 | 512 | return ret; |
8366025e DH |
513 | } |
514 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
515 | ||
96029c4e | 516 | /** |
eb04c282 | 517 | * __mnt_want_write_file - get write access to a file's mount |
96029c4e NP |
518 | * @file: the file who's mount on which to take a write |
519 | * | |
14e43bf4 EB |
520 | * This is like __mnt_want_write, but if the file is already open for writing it |
521 | * skips incrementing mnt_writers (since the open file already has a reference) | |
522 | * and instead only does the check for emergency r/o remounts. This must be | |
523 | * paired with __mnt_drop_write_file. | |
96029c4e | 524 | */ |
eb04c282 | 525 | int __mnt_want_write_file(struct file *file) |
96029c4e | 526 | { |
14e43bf4 EB |
527 | if (file->f_mode & FMODE_WRITER) { |
528 | /* | |
529 | * Superblock may have become readonly while there are still | |
530 | * writable fd's, e.g. due to a fs error with errors=remount-ro | |
531 | */ | |
532 | if (__mnt_is_readonly(file->f_path.mnt)) | |
533 | return -EROFS; | |
534 | return 0; | |
535 | } | |
536 | return __mnt_want_write(file->f_path.mnt); | |
96029c4e | 537 | } |
eb04c282 | 538 | |
7c6893e3 MS |
539 | /** |
540 | * mnt_want_write_file - get write access to a file's mount | |
541 | * @file: the file who's mount on which to take a write | |
542 | * | |
14e43bf4 EB |
543 | * This is like mnt_want_write, but if the file is already open for writing it |
544 | * skips incrementing mnt_writers (since the open file already has a reference) | |
545 | * and instead only does the freeze protection and the check for emergency r/o | |
546 | * remounts. This must be paired with mnt_drop_write_file. | |
7c6893e3 MS |
547 | */ |
548 | int mnt_want_write_file(struct file *file) | |
549 | { | |
550 | int ret; | |
551 | ||
a6795a58 | 552 | sb_start_write(file_inode(file)->i_sb); |
eb04c282 JK |
553 | ret = __mnt_want_write_file(file); |
554 | if (ret) | |
a6795a58 | 555 | sb_end_write(file_inode(file)->i_sb); |
7c6893e3 MS |
556 | return ret; |
557 | } | |
96029c4e NP |
558 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
559 | ||
8366025e | 560 | /** |
eb04c282 | 561 | * __mnt_drop_write - give up write access to a mount |
8366025e DH |
562 | * @mnt: the mount on which to give up write access |
563 | * | |
564 | * Tells the low-level filesystem that we are done | |
565 | * performing writes to it. Must be matched with | |
eb04c282 | 566 | * __mnt_want_write() call above. |
8366025e | 567 | */ |
eb04c282 | 568 | void __mnt_drop_write(struct vfsmount *mnt) |
8366025e | 569 | { |
d3ef3d73 | 570 | preempt_disable(); |
83adc753 | 571 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 572 | preempt_enable(); |
8366025e | 573 | } |
eb04c282 JK |
574 | |
575 | /** | |
576 | * mnt_drop_write - give up write access to a mount | |
577 | * @mnt: the mount on which to give up write access | |
578 | * | |
579 | * Tells the low-level filesystem that we are done performing writes to it and | |
580 | * also allows filesystem to be frozen again. Must be matched with | |
581 | * mnt_want_write() call above. | |
582 | */ | |
583 | void mnt_drop_write(struct vfsmount *mnt) | |
584 | { | |
585 | __mnt_drop_write(mnt); | |
586 | sb_end_write(mnt->mnt_sb); | |
587 | } | |
8366025e DH |
588 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
589 | ||
eb04c282 JK |
590 | void __mnt_drop_write_file(struct file *file) |
591 | { | |
14e43bf4 EB |
592 | if (!(file->f_mode & FMODE_WRITER)) |
593 | __mnt_drop_write(file->f_path.mnt); | |
eb04c282 JK |
594 | } |
595 | ||
7c6893e3 MS |
596 | void mnt_drop_write_file(struct file *file) |
597 | { | |
a6795a58 | 598 | __mnt_drop_write_file(file); |
7c6893e3 MS |
599 | sb_end_write(file_inode(file)->i_sb); |
600 | } | |
2a79f17e AV |
601 | EXPORT_SYMBOL(mnt_drop_write_file); |
602 | ||
538f4f02 CB |
603 | /** |
604 | * mnt_hold_writers - prevent write access to the given mount | |
605 | * @mnt: mnt to prevent write access to | |
606 | * | |
607 | * Prevents write access to @mnt if there are no active writers for @mnt. | |
608 | * This function needs to be called and return successfully before changing | |
609 | * properties of @mnt that need to remain stable for callers with write access | |
610 | * to @mnt. | |
611 | * | |
612 | * After this functions has been called successfully callers must pair it with | |
613 | * a call to mnt_unhold_writers() in order to stop preventing write access to | |
614 | * @mnt. | |
615 | * | |
616 | * Context: This function expects lock_mount_hash() to be held serializing | |
617 | * setting MNT_WRITE_HOLD. | |
618 | * Return: On success 0 is returned. | |
619 | * On error, -EBUSY is returned. | |
620 | */ | |
fbdc2f6c | 621 | static inline int mnt_hold_writers(struct mount *mnt) |
8366025e | 622 | { |
83adc753 | 623 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 624 | /* |
d3ef3d73 NP |
625 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
626 | * should be visible before we do. | |
3d733633 | 627 | */ |
d3ef3d73 NP |
628 | smp_mb(); |
629 | ||
3d733633 | 630 | /* |
d3ef3d73 NP |
631 | * With writers on hold, if this value is zero, then there are |
632 | * definitely no active writers (although held writers may subsequently | |
633 | * increment the count, they'll have to wait, and decrement it after | |
634 | * seeing MNT_READONLY). | |
635 | * | |
636 | * It is OK to have counter incremented on one CPU and decremented on | |
637 | * another: the sum will add up correctly. The danger would be when we | |
638 | * sum up each counter, if we read a counter before it is incremented, | |
639 | * but then read another CPU's count which it has been subsequently | |
640 | * decremented from -- we would see more decrements than we should. | |
641 | * MNT_WRITE_HOLD protects against this scenario, because | |
642 | * mnt_want_write first increments count, then smp_mb, then spins on | |
643 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
644 | * we're counting up here. | |
3d733633 | 645 | */ |
c6653a83 | 646 | if (mnt_get_writers(mnt) > 0) |
fbdc2f6c CB |
647 | return -EBUSY; |
648 | ||
649 | return 0; | |
650 | } | |
651 | ||
538f4f02 CB |
652 | /** |
653 | * mnt_unhold_writers - stop preventing write access to the given mount | |
654 | * @mnt: mnt to stop preventing write access to | |
655 | * | |
656 | * Stop preventing write access to @mnt allowing callers to gain write access | |
657 | * to @mnt again. | |
658 | * | |
659 | * This function can only be called after a successful call to | |
660 | * mnt_hold_writers(). | |
661 | * | |
662 | * Context: This function expects lock_mount_hash() to be held. | |
663 | */ | |
fbdc2f6c CB |
664 | static inline void mnt_unhold_writers(struct mount *mnt) |
665 | { | |
d3ef3d73 NP |
666 | /* |
667 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
668 | * that become unheld will see MNT_READONLY. | |
669 | */ | |
670 | smp_wmb(); | |
83adc753 | 671 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
fbdc2f6c CB |
672 | } |
673 | ||
674 | static int mnt_make_readonly(struct mount *mnt) | |
675 | { | |
676 | int ret; | |
677 | ||
678 | ret = mnt_hold_writers(mnt); | |
679 | if (!ret) | |
680 | mnt->mnt.mnt_flags |= MNT_READONLY; | |
681 | mnt_unhold_writers(mnt); | |
3d733633 | 682 | return ret; |
8366025e | 683 | } |
8366025e | 684 | |
4ed5e82f MS |
685 | int sb_prepare_remount_readonly(struct super_block *sb) |
686 | { | |
687 | struct mount *mnt; | |
688 | int err = 0; | |
689 | ||
8e8b8796 MS |
690 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
691 | if (atomic_long_read(&sb->s_remove_count)) | |
692 | return -EBUSY; | |
693 | ||
719ea2fb | 694 | lock_mount_hash(); |
4ed5e82f MS |
695 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
696 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { | |
ad1844a0 CB |
697 | err = mnt_hold_writers(mnt); |
698 | if (err) | |
4ed5e82f | 699 | break; |
4ed5e82f MS |
700 | } |
701 | } | |
8e8b8796 MS |
702 | if (!err && atomic_long_read(&sb->s_remove_count)) |
703 | err = -EBUSY; | |
704 | ||
4ed5e82f MS |
705 | if (!err) { |
706 | sb->s_readonly_remount = 1; | |
707 | smp_wmb(); | |
708 | } | |
709 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { | |
710 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) | |
711 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; | |
712 | } | |
719ea2fb | 713 | unlock_mount_hash(); |
4ed5e82f MS |
714 | |
715 | return err; | |
716 | } | |
717 | ||
b105e270 | 718 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 719 | { |
256c8aed | 720 | mnt_idmap_put(mnt_idmap(&mnt->mnt)); |
fcc139ae | 721 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 722 | #ifdef CONFIG_SMP |
68e8a9fe | 723 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 724 | #endif |
b105e270 | 725 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
726 | } |
727 | ||
8ffcb32e DH |
728 | static void delayed_free_vfsmnt(struct rcu_head *head) |
729 | { | |
730 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); | |
731 | } | |
732 | ||
48a066e7 | 733 | /* call under rcu_read_lock */ |
294d71ff | 734 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
48a066e7 AV |
735 | { |
736 | struct mount *mnt; | |
737 | if (read_seqretry(&mount_lock, seq)) | |
294d71ff | 738 | return 1; |
48a066e7 | 739 | if (bastard == NULL) |
294d71ff | 740 | return 0; |
48a066e7 AV |
741 | mnt = real_mount(bastard); |
742 | mnt_add_count(mnt, 1); | |
119e1ef8 | 743 | smp_mb(); // see mntput_no_expire() |
48a066e7 | 744 | if (likely(!read_seqretry(&mount_lock, seq))) |
294d71ff | 745 | return 0; |
48a066e7 AV |
746 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
747 | mnt_add_count(mnt, -1); | |
294d71ff AV |
748 | return 1; |
749 | } | |
119e1ef8 AV |
750 | lock_mount_hash(); |
751 | if (unlikely(bastard->mnt_flags & MNT_DOOMED)) { | |
752 | mnt_add_count(mnt, -1); | |
753 | unlock_mount_hash(); | |
754 | return 1; | |
755 | } | |
756 | unlock_mount_hash(); | |
757 | /* caller will mntput() */ | |
294d71ff AV |
758 | return -1; |
759 | } | |
760 | ||
761 | /* call under rcu_read_lock */ | |
7e4745a0 | 762 | static bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
294d71ff AV |
763 | { |
764 | int res = __legitimize_mnt(bastard, seq); | |
765 | if (likely(!res)) | |
766 | return true; | |
767 | if (unlikely(res < 0)) { | |
768 | rcu_read_unlock(); | |
769 | mntput(bastard); | |
770 | rcu_read_lock(); | |
48a066e7 | 771 | } |
48a066e7 AV |
772 | return false; |
773 | } | |
774 | ||
1da177e4 | 775 | /* |
474279dc | 776 | * find the first mount at @dentry on vfsmount @mnt. |
48a066e7 | 777 | * call under rcu_read_lock() |
1da177e4 | 778 | */ |
474279dc | 779 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 780 | { |
38129a13 | 781 | struct hlist_head *head = m_hash(mnt, dentry); |
474279dc AV |
782 | struct mount *p; |
783 | ||
38129a13 | 784 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
474279dc AV |
785 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
786 | return p; | |
787 | return NULL; | |
788 | } | |
789 | ||
a05964f3 | 790 | /* |
f015f126 DH |
791 | * lookup_mnt - Return the first child mount mounted at path |
792 | * | |
793 | * "First" means first mounted chronologically. If you create the | |
794 | * following mounts: | |
795 | * | |
796 | * mount /dev/sda1 /mnt | |
797 | * mount /dev/sda2 /mnt | |
798 | * mount /dev/sda3 /mnt | |
799 | * | |
800 | * Then lookup_mnt() on the base /mnt dentry in the root mount will | |
801 | * return successively the root dentry and vfsmount of /dev/sda1, then | |
802 | * /dev/sda2, then /dev/sda3, then NULL. | |
803 | * | |
804 | * lookup_mnt takes a reference to the found vfsmount. | |
a05964f3 | 805 | */ |
ca71cf71 | 806 | struct vfsmount *lookup_mnt(const struct path *path) |
a05964f3 | 807 | { |
c7105365 | 808 | struct mount *child_mnt; |
48a066e7 AV |
809 | struct vfsmount *m; |
810 | unsigned seq; | |
99b7db7b | 811 | |
48a066e7 AV |
812 | rcu_read_lock(); |
813 | do { | |
814 | seq = read_seqbegin(&mount_lock); | |
815 | child_mnt = __lookup_mnt(path->mnt, path->dentry); | |
816 | m = child_mnt ? &child_mnt->mnt : NULL; | |
817 | } while (!legitimize_mnt(m, seq)); | |
818 | rcu_read_unlock(); | |
819 | return m; | |
a05964f3 RP |
820 | } |
821 | ||
9f6c61f9 MS |
822 | static inline void lock_ns_list(struct mnt_namespace *ns) |
823 | { | |
824 | spin_lock(&ns->ns_lock); | |
825 | } | |
826 | ||
827 | static inline void unlock_ns_list(struct mnt_namespace *ns) | |
828 | { | |
829 | spin_unlock(&ns->ns_lock); | |
830 | } | |
831 | ||
832 | static inline bool mnt_is_cursor(struct mount *mnt) | |
833 | { | |
834 | return mnt->mnt.mnt_flags & MNT_CURSOR; | |
835 | } | |
836 | ||
7af1364f EB |
837 | /* |
838 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the | |
839 | * current mount namespace. | |
840 | * | |
841 | * The common case is dentries are not mountpoints at all and that | |
842 | * test is handled inline. For the slow case when we are actually | |
843 | * dealing with a mountpoint of some kind, walk through all of the | |
844 | * mounts in the current mount namespace and test to see if the dentry | |
845 | * is a mountpoint. | |
846 | * | |
847 | * The mount_hashtable is not usable in the context because we | |
848 | * need to identify all mounts that may be in the current mount | |
849 | * namespace not just a mount that happens to have some specified | |
850 | * parent mount. | |
851 | */ | |
852 | bool __is_local_mountpoint(struct dentry *dentry) | |
853 | { | |
854 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
855 | struct mount *mnt; | |
856 | bool is_covered = false; | |
857 | ||
7af1364f | 858 | down_read(&namespace_sem); |
9f6c61f9 | 859 | lock_ns_list(ns); |
7af1364f | 860 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
9f6c61f9 MS |
861 | if (mnt_is_cursor(mnt)) |
862 | continue; | |
7af1364f EB |
863 | is_covered = (mnt->mnt_mountpoint == dentry); |
864 | if (is_covered) | |
865 | break; | |
866 | } | |
9f6c61f9 | 867 | unlock_ns_list(ns); |
7af1364f | 868 | up_read(&namespace_sem); |
5ad05cc8 | 869 | |
7af1364f EB |
870 | return is_covered; |
871 | } | |
872 | ||
e2dfa935 | 873 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
84d17192 | 874 | { |
0818bf27 | 875 | struct hlist_head *chain = mp_hash(dentry); |
84d17192 AV |
876 | struct mountpoint *mp; |
877 | ||
0818bf27 | 878 | hlist_for_each_entry(mp, chain, m_hash) { |
84d17192 | 879 | if (mp->m_dentry == dentry) { |
84d17192 AV |
880 | mp->m_count++; |
881 | return mp; | |
882 | } | |
883 | } | |
e2dfa935 EB |
884 | return NULL; |
885 | } | |
886 | ||
3895dbf8 | 887 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
e2dfa935 | 888 | { |
3895dbf8 | 889 | struct mountpoint *mp, *new = NULL; |
e2dfa935 | 890 | int ret; |
84d17192 | 891 | |
3895dbf8 | 892 | if (d_mountpoint(dentry)) { |
1e9c75fb BC |
893 | /* might be worth a WARN_ON() */ |
894 | if (d_unlinked(dentry)) | |
895 | return ERR_PTR(-ENOENT); | |
3895dbf8 EB |
896 | mountpoint: |
897 | read_seqlock_excl(&mount_lock); | |
898 | mp = lookup_mountpoint(dentry); | |
899 | read_sequnlock_excl(&mount_lock); | |
900 | if (mp) | |
901 | goto done; | |
902 | } | |
903 | ||
904 | if (!new) | |
905 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); | |
906 | if (!new) | |
84d17192 AV |
907 | return ERR_PTR(-ENOMEM); |
908 | ||
3895dbf8 EB |
909 | |
910 | /* Exactly one processes may set d_mounted */ | |
eed81007 | 911 | ret = d_set_mounted(dentry); |
eed81007 | 912 | |
3895dbf8 EB |
913 | /* Someone else set d_mounted? */ |
914 | if (ret == -EBUSY) | |
915 | goto mountpoint; | |
916 | ||
917 | /* The dentry is not available as a mountpoint? */ | |
918 | mp = ERR_PTR(ret); | |
919 | if (ret) | |
920 | goto done; | |
921 | ||
922 | /* Add the new mountpoint to the hash table */ | |
923 | read_seqlock_excl(&mount_lock); | |
4edbe133 | 924 | new->m_dentry = dget(dentry); |
3895dbf8 EB |
925 | new->m_count = 1; |
926 | hlist_add_head(&new->m_hash, mp_hash(dentry)); | |
927 | INIT_HLIST_HEAD(&new->m_list); | |
928 | read_sequnlock_excl(&mount_lock); | |
929 | ||
930 | mp = new; | |
931 | new = NULL; | |
932 | done: | |
933 | kfree(new); | |
84d17192 AV |
934 | return mp; |
935 | } | |
936 | ||
4edbe133 AV |
937 | /* |
938 | * vfsmount lock must be held. Additionally, the caller is responsible | |
939 | * for serializing calls for given disposal list. | |
940 | */ | |
941 | static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) | |
84d17192 AV |
942 | { |
943 | if (!--mp->m_count) { | |
944 | struct dentry *dentry = mp->m_dentry; | |
0a5eb7c8 | 945 | BUG_ON(!hlist_empty(&mp->m_list)); |
84d17192 AV |
946 | spin_lock(&dentry->d_lock); |
947 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
948 | spin_unlock(&dentry->d_lock); | |
4edbe133 | 949 | dput_to_list(dentry, list); |
0818bf27 | 950 | hlist_del(&mp->m_hash); |
84d17192 AV |
951 | kfree(mp); |
952 | } | |
953 | } | |
954 | ||
4edbe133 AV |
955 | /* called with namespace_lock and vfsmount lock */ |
956 | static void put_mountpoint(struct mountpoint *mp) | |
957 | { | |
958 | __put_mountpoint(mp, &ex_mountpoints); | |
959 | } | |
960 | ||
143c8c91 | 961 | static inline int check_mnt(struct mount *mnt) |
1da177e4 | 962 | { |
6b3286ed | 963 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
964 | } |
965 | ||
99b7db7b NP |
966 | /* |
967 | * vfsmount lock must be held for write | |
968 | */ | |
6b3286ed | 969 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
970 | { |
971 | if (ns) { | |
972 | ns->event = ++event; | |
973 | wake_up_interruptible(&ns->poll); | |
974 | } | |
975 | } | |
976 | ||
99b7db7b NP |
977 | /* |
978 | * vfsmount lock must be held for write | |
979 | */ | |
6b3286ed | 980 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
981 | { |
982 | if (ns && ns->event != event) { | |
983 | ns->event = event; | |
984 | wake_up_interruptible(&ns->poll); | |
985 | } | |
986 | } | |
987 | ||
99b7db7b NP |
988 | /* |
989 | * vfsmount lock must be held for write | |
990 | */ | |
e4e59906 | 991 | static struct mountpoint *unhash_mnt(struct mount *mnt) |
419148da | 992 | { |
e4e59906 | 993 | struct mountpoint *mp; |
0714a533 | 994 | mnt->mnt_parent = mnt; |
a73324da | 995 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 996 | list_del_init(&mnt->mnt_child); |
38129a13 | 997 | hlist_del_init_rcu(&mnt->mnt_hash); |
0a5eb7c8 | 998 | hlist_del_init(&mnt->mnt_mp_list); |
e4e59906 | 999 | mp = mnt->mnt_mp; |
84d17192 | 1000 | mnt->mnt_mp = NULL; |
e4e59906 | 1001 | return mp; |
7bdb11de EB |
1002 | } |
1003 | ||
6a46c573 EB |
1004 | /* |
1005 | * vfsmount lock must be held for write | |
1006 | */ | |
1007 | static void umount_mnt(struct mount *mnt) | |
1008 | { | |
e4e59906 | 1009 | put_mountpoint(unhash_mnt(mnt)); |
6a46c573 EB |
1010 | } |
1011 | ||
99b7db7b NP |
1012 | /* |
1013 | * vfsmount lock must be held for write | |
1014 | */ | |
84d17192 AV |
1015 | void mnt_set_mountpoint(struct mount *mnt, |
1016 | struct mountpoint *mp, | |
44d964d6 | 1017 | struct mount *child_mnt) |
b90fa9ae | 1018 | { |
84d17192 | 1019 | mp->m_count++; |
3a2393d7 | 1020 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
4edbe133 | 1021 | child_mnt->mnt_mountpoint = mp->m_dentry; |
3a2393d7 | 1022 | child_mnt->mnt_parent = mnt; |
84d17192 | 1023 | child_mnt->mnt_mp = mp; |
0a5eb7c8 | 1024 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
b90fa9ae RP |
1025 | } |
1026 | ||
1064f874 EB |
1027 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
1028 | { | |
1029 | hlist_add_head_rcu(&mnt->mnt_hash, | |
1030 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); | |
1031 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
1032 | } | |
1033 | ||
99b7db7b NP |
1034 | /* |
1035 | * vfsmount lock must be held for write | |
1036 | */ | |
84d17192 AV |
1037 | static void attach_mnt(struct mount *mnt, |
1038 | struct mount *parent, | |
1039 | struct mountpoint *mp) | |
1da177e4 | 1040 | { |
84d17192 | 1041 | mnt_set_mountpoint(parent, mp, mnt); |
1064f874 | 1042 | __attach_mnt(mnt, parent); |
b90fa9ae RP |
1043 | } |
1044 | ||
1064f874 | 1045 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
12a5b529 | 1046 | { |
1064f874 | 1047 | struct mountpoint *old_mp = mnt->mnt_mp; |
1064f874 EB |
1048 | struct mount *old_parent = mnt->mnt_parent; |
1049 | ||
1050 | list_del_init(&mnt->mnt_child); | |
1051 | hlist_del_init(&mnt->mnt_mp_list); | |
1052 | hlist_del_init_rcu(&mnt->mnt_hash); | |
1053 | ||
1054 | attach_mnt(mnt, parent, mp); | |
1055 | ||
1056 | put_mountpoint(old_mp); | |
1064f874 | 1057 | mnt_add_count(old_parent, -1); |
12a5b529 AV |
1058 | } |
1059 | ||
b90fa9ae | 1060 | /* |
99b7db7b | 1061 | * vfsmount lock must be held for write |
b90fa9ae | 1062 | */ |
1064f874 | 1063 | static void commit_tree(struct mount *mnt) |
b90fa9ae | 1064 | { |
0714a533 | 1065 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 1066 | struct mount *m; |
b90fa9ae | 1067 | LIST_HEAD(head); |
143c8c91 | 1068 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae | 1069 | |
0714a533 | 1070 | BUG_ON(parent == mnt); |
b90fa9ae | 1071 | |
1a4eeaf2 | 1072 | list_add_tail(&head, &mnt->mnt_list); |
f7a99c5b | 1073 | list_for_each_entry(m, &head, mnt_list) |
143c8c91 | 1074 | m->mnt_ns = n; |
f03c6599 | 1075 | |
b90fa9ae RP |
1076 | list_splice(&head, n->list.prev); |
1077 | ||
d2921684 EB |
1078 | n->mounts += n->pending_mounts; |
1079 | n->pending_mounts = 0; | |
1080 | ||
1064f874 | 1081 | __attach_mnt(mnt, parent); |
6b3286ed | 1082 | touch_mnt_namespace(n); |
1da177e4 LT |
1083 | } |
1084 | ||
909b0a88 | 1085 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
1da177e4 | 1086 | { |
6b41d536 AV |
1087 | struct list_head *next = p->mnt_mounts.next; |
1088 | if (next == &p->mnt_mounts) { | |
1da177e4 | 1089 | while (1) { |
909b0a88 | 1090 | if (p == root) |
1da177e4 | 1091 | return NULL; |
6b41d536 AV |
1092 | next = p->mnt_child.next; |
1093 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 1094 | break; |
0714a533 | 1095 | p = p->mnt_parent; |
1da177e4 LT |
1096 | } |
1097 | } | |
6b41d536 | 1098 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
1099 | } |
1100 | ||
315fc83e | 1101 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 1102 | { |
6b41d536 AV |
1103 | struct list_head *prev = p->mnt_mounts.prev; |
1104 | while (prev != &p->mnt_mounts) { | |
1105 | p = list_entry(prev, struct mount, mnt_child); | |
1106 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
1107 | } |
1108 | return p; | |
1109 | } | |
1110 | ||
8f291889 AV |
1111 | /** |
1112 | * vfs_create_mount - Create a mount for a configured superblock | |
1113 | * @fc: The configuration context with the superblock attached | |
1114 | * | |
1115 | * Create a mount to an already configured superblock. If necessary, the | |
1116 | * caller should invoke vfs_get_tree() before calling this. | |
1117 | * | |
1118 | * Note that this does not attach the mount to anything. | |
1119 | */ | |
1120 | struct vfsmount *vfs_create_mount(struct fs_context *fc) | |
9d412a43 | 1121 | { |
b105e270 | 1122 | struct mount *mnt; |
9d412a43 | 1123 | |
8f291889 AV |
1124 | if (!fc->root) |
1125 | return ERR_PTR(-EINVAL); | |
9d412a43 | 1126 | |
8f291889 | 1127 | mnt = alloc_vfsmnt(fc->source ?: "none"); |
9d412a43 AV |
1128 | if (!mnt) |
1129 | return ERR_PTR(-ENOMEM); | |
1130 | ||
8f291889 | 1131 | if (fc->sb_flags & SB_KERNMOUNT) |
b105e270 | 1132 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 | 1133 | |
8f291889 AV |
1134 | atomic_inc(&fc->root->d_sb->s_active); |
1135 | mnt->mnt.mnt_sb = fc->root->d_sb; | |
1136 | mnt->mnt.mnt_root = dget(fc->root); | |
1137 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1138 | mnt->mnt_parent = mnt; | |
9d412a43 | 1139 | |
719ea2fb | 1140 | lock_mount_hash(); |
8f291889 | 1141 | list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); |
719ea2fb | 1142 | unlock_mount_hash(); |
b105e270 | 1143 | return &mnt->mnt; |
9d412a43 | 1144 | } |
8f291889 AV |
1145 | EXPORT_SYMBOL(vfs_create_mount); |
1146 | ||
1147 | struct vfsmount *fc_mount(struct fs_context *fc) | |
1148 | { | |
1149 | int err = vfs_get_tree(fc); | |
1150 | if (!err) { | |
1151 | up_write(&fc->root->d_sb->s_umount); | |
1152 | return vfs_create_mount(fc); | |
1153 | } | |
1154 | return ERR_PTR(err); | |
1155 | } | |
1156 | EXPORT_SYMBOL(fc_mount); | |
1157 | ||
9bc61ab1 DH |
1158 | struct vfsmount *vfs_kern_mount(struct file_system_type *type, |
1159 | int flags, const char *name, | |
1160 | void *data) | |
9d412a43 | 1161 | { |
9bc61ab1 | 1162 | struct fs_context *fc; |
8f291889 | 1163 | struct vfsmount *mnt; |
9bc61ab1 | 1164 | int ret = 0; |
9d412a43 AV |
1165 | |
1166 | if (!type) | |
3e1aeb00 | 1167 | return ERR_PTR(-EINVAL); |
9d412a43 | 1168 | |
9bc61ab1 DH |
1169 | fc = fs_context_for_mount(type, flags); |
1170 | if (IS_ERR(fc)) | |
1171 | return ERR_CAST(fc); | |
1172 | ||
3e1aeb00 DH |
1173 | if (name) |
1174 | ret = vfs_parse_fs_string(fc, "source", | |
1175 | name, strlen(name)); | |
9bc61ab1 DH |
1176 | if (!ret) |
1177 | ret = parse_monolithic_mount_data(fc, data); | |
1178 | if (!ret) | |
8f291889 AV |
1179 | mnt = fc_mount(fc); |
1180 | else | |
1181 | mnt = ERR_PTR(ret); | |
9d412a43 | 1182 | |
9bc61ab1 | 1183 | put_fs_context(fc); |
8f291889 | 1184 | return mnt; |
9d412a43 AV |
1185 | } |
1186 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
1187 | ||
93faccbb EB |
1188 | struct vfsmount * |
1189 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, | |
1190 | const char *name, void *data) | |
1191 | { | |
1192 | /* Until it is worked out how to pass the user namespace | |
1193 | * through from the parent mount to the submount don't support | |
1194 | * unprivileged mounts with submounts. | |
1195 | */ | |
1196 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) | |
1197 | return ERR_PTR(-EPERM); | |
1198 | ||
e462ec50 | 1199 | return vfs_kern_mount(type, SB_SUBMOUNT, name, data); |
93faccbb EB |
1200 | } |
1201 | EXPORT_SYMBOL_GPL(vfs_submount); | |
1202 | ||
87129cc0 | 1203 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 1204 | int flag) |
1da177e4 | 1205 | { |
87129cc0 | 1206 | struct super_block *sb = old->mnt.mnt_sb; |
be34d1a3 DH |
1207 | struct mount *mnt; |
1208 | int err; | |
1da177e4 | 1209 | |
be34d1a3 DH |
1210 | mnt = alloc_vfsmnt(old->mnt_devname); |
1211 | if (!mnt) | |
1212 | return ERR_PTR(-ENOMEM); | |
719f5d7f | 1213 | |
7a472ef4 | 1214 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
be34d1a3 DH |
1215 | mnt->mnt_group_id = 0; /* not a peer of original */ |
1216 | else | |
1217 | mnt->mnt_group_id = old->mnt_group_id; | |
b90fa9ae | 1218 | |
be34d1a3 DH |
1219 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
1220 | err = mnt_alloc_group_id(mnt); | |
1221 | if (err) | |
1222 | goto out_free; | |
1da177e4 | 1223 | } |
be34d1a3 | 1224 | |
16a34adb AV |
1225 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
1226 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); | |
5ff9d8a6 | 1227 | |
be34d1a3 | 1228 | atomic_inc(&sb->s_active); |
256c8aed CB |
1229 | mnt->mnt.mnt_idmap = mnt_idmap_get(mnt_idmap(&old->mnt)); |
1230 | ||
be34d1a3 DH |
1231 | mnt->mnt.mnt_sb = sb; |
1232 | mnt->mnt.mnt_root = dget(root); | |
1233 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1234 | mnt->mnt_parent = mnt; | |
719ea2fb | 1235 | lock_mount_hash(); |
be34d1a3 | 1236 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
719ea2fb | 1237 | unlock_mount_hash(); |
be34d1a3 | 1238 | |
7a472ef4 EB |
1239 | if ((flag & CL_SLAVE) || |
1240 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { | |
be34d1a3 DH |
1241 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
1242 | mnt->mnt_master = old; | |
1243 | CLEAR_MNT_SHARED(mnt); | |
1244 | } else if (!(flag & CL_PRIVATE)) { | |
1245 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) | |
1246 | list_add(&mnt->mnt_share, &old->mnt_share); | |
1247 | if (IS_MNT_SLAVE(old)) | |
1248 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
1249 | mnt->mnt_master = old->mnt_master; | |
5235d448 AV |
1250 | } else { |
1251 | CLEAR_MNT_SHARED(mnt); | |
be34d1a3 DH |
1252 | } |
1253 | if (flag & CL_MAKE_SHARED) | |
1254 | set_mnt_shared(mnt); | |
1255 | ||
1256 | /* stick the duplicate mount on the same expiry list | |
1257 | * as the original if that was on one */ | |
1258 | if (flag & CL_EXPIRE) { | |
1259 | if (!list_empty(&old->mnt_expire)) | |
1260 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
1261 | } | |
1262 | ||
cb338d06 | 1263 | return mnt; |
719f5d7f MS |
1264 | |
1265 | out_free: | |
8ffcb32e | 1266 | mnt_free_id(mnt); |
719f5d7f | 1267 | free_vfsmnt(mnt); |
be34d1a3 | 1268 | return ERR_PTR(err); |
1da177e4 LT |
1269 | } |
1270 | ||
9ea459e1 AV |
1271 | static void cleanup_mnt(struct mount *mnt) |
1272 | { | |
56cbb429 AV |
1273 | struct hlist_node *p; |
1274 | struct mount *m; | |
9ea459e1 | 1275 | /* |
56cbb429 AV |
1276 | * The warning here probably indicates that somebody messed |
1277 | * up a mnt_want/drop_write() pair. If this happens, the | |
1278 | * filesystem was probably unable to make r/w->r/o transitions. | |
9ea459e1 AV |
1279 | * The locking used to deal with mnt_count decrement provides barriers, |
1280 | * so mnt_get_writers() below is safe. | |
1281 | */ | |
1282 | WARN_ON(mnt_get_writers(mnt)); | |
1283 | if (unlikely(mnt->mnt_pins.first)) | |
1284 | mnt_pin_kill(mnt); | |
56cbb429 AV |
1285 | hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) { |
1286 | hlist_del(&m->mnt_umount); | |
1287 | mntput(&m->mnt); | |
1288 | } | |
9ea459e1 AV |
1289 | fsnotify_vfsmount_delete(&mnt->mnt); |
1290 | dput(mnt->mnt.mnt_root); | |
1291 | deactivate_super(mnt->mnt.mnt_sb); | |
1292 | mnt_free_id(mnt); | |
1293 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); | |
1294 | } | |
1295 | ||
1296 | static void __cleanup_mnt(struct rcu_head *head) | |
1297 | { | |
1298 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); | |
1299 | } | |
1300 | ||
1301 | static LLIST_HEAD(delayed_mntput_list); | |
1302 | static void delayed_mntput(struct work_struct *unused) | |
1303 | { | |
1304 | struct llist_node *node = llist_del_all(&delayed_mntput_list); | |
29785735 | 1305 | struct mount *m, *t; |
9ea459e1 | 1306 | |
29785735 BP |
1307 | llist_for_each_entry_safe(m, t, node, mnt_llist) |
1308 | cleanup_mnt(m); | |
9ea459e1 AV |
1309 | } |
1310 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); | |
1311 | ||
900148dc | 1312 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 1313 | { |
4edbe133 | 1314 | LIST_HEAD(list); |
edf7ddbf | 1315 | int count; |
4edbe133 | 1316 | |
48a066e7 | 1317 | rcu_read_lock(); |
9ea0a46c AV |
1318 | if (likely(READ_ONCE(mnt->mnt_ns))) { |
1319 | /* | |
1320 | * Since we don't do lock_mount_hash() here, | |
1321 | * ->mnt_ns can change under us. However, if it's | |
1322 | * non-NULL, then there's a reference that won't | |
1323 | * be dropped until after an RCU delay done after | |
1324 | * turning ->mnt_ns NULL. So if we observe it | |
1325 | * non-NULL under rcu_read_lock(), the reference | |
1326 | * we are dropping is not the final one. | |
1327 | */ | |
1328 | mnt_add_count(mnt, -1); | |
48a066e7 | 1329 | rcu_read_unlock(); |
f03c6599 | 1330 | return; |
b3e19d92 | 1331 | } |
719ea2fb | 1332 | lock_mount_hash(); |
119e1ef8 AV |
1333 | /* |
1334 | * make sure that if __legitimize_mnt() has not seen us grab | |
1335 | * mount_lock, we'll see their refcount increment here. | |
1336 | */ | |
1337 | smp_mb(); | |
9ea0a46c | 1338 | mnt_add_count(mnt, -1); |
edf7ddbf EB |
1339 | count = mnt_get_count(mnt); |
1340 | if (count != 0) { | |
1341 | WARN_ON(count < 0); | |
48a066e7 | 1342 | rcu_read_unlock(); |
719ea2fb | 1343 | unlock_mount_hash(); |
99b7db7b NP |
1344 | return; |
1345 | } | |
48a066e7 AV |
1346 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
1347 | rcu_read_unlock(); | |
1348 | unlock_mount_hash(); | |
1349 | return; | |
1350 | } | |
1351 | mnt->mnt.mnt_flags |= MNT_DOOMED; | |
1352 | rcu_read_unlock(); | |
962830df | 1353 | |
39f7c4db | 1354 | list_del(&mnt->mnt_instance); |
ce07d891 EB |
1355 | |
1356 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { | |
1357 | struct mount *p, *tmp; | |
1358 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { | |
4edbe133 | 1359 | __put_mountpoint(unhash_mnt(p), &list); |
56cbb429 | 1360 | hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children); |
ce07d891 EB |
1361 | } |
1362 | } | |
719ea2fb | 1363 | unlock_mount_hash(); |
4edbe133 | 1364 | shrink_dentry_list(&list); |
649a795a | 1365 | |
9ea459e1 AV |
1366 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
1367 | struct task_struct *task = current; | |
1368 | if (likely(!(task->flags & PF_KTHREAD))) { | |
1369 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); | |
91989c70 | 1370 | if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME)) |
9ea459e1 AV |
1371 | return; |
1372 | } | |
1373 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) | |
1374 | schedule_delayed_work(&delayed_mntput_work, 1); | |
1375 | return; | |
1376 | } | |
1377 | cleanup_mnt(mnt); | |
b3e19d92 | 1378 | } |
b3e19d92 NP |
1379 | |
1380 | void mntput(struct vfsmount *mnt) | |
1381 | { | |
1382 | if (mnt) { | |
863d684f | 1383 | struct mount *m = real_mount(mnt); |
b3e19d92 | 1384 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
863d684f AV |
1385 | if (unlikely(m->mnt_expiry_mark)) |
1386 | m->mnt_expiry_mark = 0; | |
1387 | mntput_no_expire(m); | |
b3e19d92 NP |
1388 | } |
1389 | } | |
1390 | EXPORT_SYMBOL(mntput); | |
1391 | ||
1392 | struct vfsmount *mntget(struct vfsmount *mnt) | |
1393 | { | |
1394 | if (mnt) | |
83adc753 | 1395 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
1396 | return mnt; |
1397 | } | |
1398 | EXPORT_SYMBOL(mntget); | |
1399 | ||
1f287bc4 RD |
1400 | /** |
1401 | * path_is_mountpoint() - Check if path is a mount in the current namespace. | |
1402 | * @path: path to check | |
c6609c0a IK |
1403 | * |
1404 | * d_mountpoint() can only be used reliably to establish if a dentry is | |
1405 | * not mounted in any namespace and that common case is handled inline. | |
1406 | * d_mountpoint() isn't aware of the possibility there may be multiple | |
1407 | * mounts using a given dentry in a different namespace. This function | |
1408 | * checks if the passed in path is a mountpoint rather than the dentry | |
1409 | * alone. | |
1410 | */ | |
1411 | bool path_is_mountpoint(const struct path *path) | |
1412 | { | |
1413 | unsigned seq; | |
1414 | bool res; | |
1415 | ||
1416 | if (!d_mountpoint(path->dentry)) | |
1417 | return false; | |
1418 | ||
1419 | rcu_read_lock(); | |
1420 | do { | |
1421 | seq = read_seqbegin(&mount_lock); | |
1422 | res = __path_is_mountpoint(path); | |
1423 | } while (read_seqretry(&mount_lock, seq)); | |
1424 | rcu_read_unlock(); | |
1425 | ||
1426 | return res; | |
1427 | } | |
1428 | EXPORT_SYMBOL(path_is_mountpoint); | |
1429 | ||
ca71cf71 | 1430 | struct vfsmount *mnt_clone_internal(const struct path *path) |
7b7b1ace | 1431 | { |
3064c356 AV |
1432 | struct mount *p; |
1433 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); | |
1434 | if (IS_ERR(p)) | |
1435 | return ERR_CAST(p); | |
1436 | p->mnt.mnt_flags |= MNT_INTERNAL; | |
1437 | return &p->mnt; | |
7b7b1ace | 1438 | } |
1da177e4 | 1439 | |
a1a2c409 | 1440 | #ifdef CONFIG_PROC_FS |
9f6c61f9 MS |
1441 | static struct mount *mnt_list_next(struct mnt_namespace *ns, |
1442 | struct list_head *p) | |
1443 | { | |
1444 | struct mount *mnt, *ret = NULL; | |
1445 | ||
1446 | lock_ns_list(ns); | |
1447 | list_for_each_continue(p, &ns->list) { | |
1448 | mnt = list_entry(p, typeof(*mnt), mnt_list); | |
1449 | if (!mnt_is_cursor(mnt)) { | |
1450 | ret = mnt; | |
1451 | break; | |
1452 | } | |
1453 | } | |
1454 | unlock_ns_list(ns); | |
1455 | ||
1456 | return ret; | |
1457 | } | |
1458 | ||
0226f492 | 1459 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
1da177e4 LT |
1460 | static void *m_start(struct seq_file *m, loff_t *pos) |
1461 | { | |
ede1bf0d | 1462 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1463 | struct list_head *prev; |
1da177e4 | 1464 | |
390c6843 | 1465 | down_read(&namespace_sem); |
9f6c61f9 MS |
1466 | if (!*pos) { |
1467 | prev = &p->ns->list; | |
1468 | } else { | |
1469 | prev = &p->cursor.mnt_list; | |
1470 | ||
1471 | /* Read after we'd reached the end? */ | |
1472 | if (list_empty(prev)) | |
1473 | return NULL; | |
c7999c36 AV |
1474 | } |
1475 | ||
9f6c61f9 | 1476 | return mnt_list_next(p->ns, prev); |
1da177e4 LT |
1477 | } |
1478 | ||
1479 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
1480 | { | |
ede1bf0d | 1481 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1482 | struct mount *mnt = v; |
b0765fb8 | 1483 | |
9f6c61f9 MS |
1484 | ++*pos; |
1485 | return mnt_list_next(p->ns, &mnt->mnt_list); | |
1da177e4 LT |
1486 | } |
1487 | ||
1488 | static void m_stop(struct seq_file *m, void *v) | |
1489 | { | |
9f6c61f9 MS |
1490 | struct proc_mounts *p = m->private; |
1491 | struct mount *mnt = v; | |
1492 | ||
1493 | lock_ns_list(p->ns); | |
1494 | if (mnt) | |
1495 | list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); | |
1496 | else | |
1497 | list_del_init(&p->cursor.mnt_list); | |
1498 | unlock_ns_list(p->ns); | |
390c6843 | 1499 | up_read(&namespace_sem); |
1da177e4 LT |
1500 | } |
1501 | ||
0226f492 | 1502 | static int m_show(struct seq_file *m, void *v) |
2d4d4864 | 1503 | { |
ede1bf0d | 1504 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1505 | struct mount *r = v; |
0226f492 | 1506 | return p->show(m, &r->mnt); |
1da177e4 LT |
1507 | } |
1508 | ||
a1a2c409 | 1509 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1510 | .start = m_start, |
1511 | .next = m_next, | |
1512 | .stop = m_stop, | |
0226f492 | 1513 | .show = m_show, |
b4629fe2 | 1514 | }; |
9f6c61f9 MS |
1515 | |
1516 | void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) | |
1517 | { | |
1518 | down_read(&namespace_sem); | |
1519 | lock_ns_list(ns); | |
1520 | list_del(&cursor->mnt_list); | |
1521 | unlock_ns_list(ns); | |
1522 | up_read(&namespace_sem); | |
1523 | } | |
a1a2c409 | 1524 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1525 | |
1da177e4 LT |
1526 | /** |
1527 | * may_umount_tree - check if a mount tree is busy | |
1f287bc4 | 1528 | * @m: root of mount tree |
1da177e4 LT |
1529 | * |
1530 | * This is called to check if a tree of mounts has any | |
1531 | * open files, pwds, chroots or sub mounts that are | |
1532 | * busy. | |
1533 | */ | |
909b0a88 | 1534 | int may_umount_tree(struct vfsmount *m) |
1da177e4 | 1535 | { |
909b0a88 | 1536 | struct mount *mnt = real_mount(m); |
36341f64 RP |
1537 | int actual_refs = 0; |
1538 | int minimum_refs = 0; | |
315fc83e | 1539 | struct mount *p; |
909b0a88 | 1540 | BUG_ON(!m); |
1da177e4 | 1541 | |
b3e19d92 | 1542 | /* write lock needed for mnt_get_count */ |
719ea2fb | 1543 | lock_mount_hash(); |
909b0a88 | 1544 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
83adc753 | 1545 | actual_refs += mnt_get_count(p); |
1da177e4 | 1546 | minimum_refs += 2; |
1da177e4 | 1547 | } |
719ea2fb | 1548 | unlock_mount_hash(); |
1da177e4 LT |
1549 | |
1550 | if (actual_refs > minimum_refs) | |
e3474a8e | 1551 | return 0; |
1da177e4 | 1552 | |
e3474a8e | 1553 | return 1; |
1da177e4 LT |
1554 | } |
1555 | ||
1556 | EXPORT_SYMBOL(may_umount_tree); | |
1557 | ||
1558 | /** | |
1559 | * may_umount - check if a mount point is busy | |
1560 | * @mnt: root of mount | |
1561 | * | |
1562 | * This is called to check if a mount point has any | |
1563 | * open files, pwds, chroots or sub mounts. If the | |
1564 | * mount has sub mounts this will return busy | |
1565 | * regardless of whether the sub mounts are busy. | |
1566 | * | |
1567 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1568 | * give false negatives. The main reason why it's here is that we need | |
1569 | * a non-destructive way to look for easily umountable filesystems. | |
1570 | */ | |
1571 | int may_umount(struct vfsmount *mnt) | |
1572 | { | |
e3474a8e | 1573 | int ret = 1; |
8ad08d8a | 1574 | down_read(&namespace_sem); |
719ea2fb | 1575 | lock_mount_hash(); |
1ab59738 | 1576 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1577 | ret = 0; |
719ea2fb | 1578 | unlock_mount_hash(); |
8ad08d8a | 1579 | up_read(&namespace_sem); |
a05964f3 | 1580 | return ret; |
1da177e4 LT |
1581 | } |
1582 | ||
1583 | EXPORT_SYMBOL(may_umount); | |
1584 | ||
97216be0 | 1585 | static void namespace_unlock(void) |
70fbcdf4 | 1586 | { |
a3b3c562 | 1587 | struct hlist_head head; |
56cbb429 AV |
1588 | struct hlist_node *p; |
1589 | struct mount *m; | |
4edbe133 | 1590 | LIST_HEAD(list); |
97216be0 | 1591 | |
a3b3c562 | 1592 | hlist_move_list(&unmounted, &head); |
4edbe133 | 1593 | list_splice_init(&ex_mountpoints, &list); |
97216be0 | 1594 | |
97216be0 AV |
1595 | up_write(&namespace_sem); |
1596 | ||
4edbe133 AV |
1597 | shrink_dentry_list(&list); |
1598 | ||
a3b3c562 EB |
1599 | if (likely(hlist_empty(&head))) |
1600 | return; | |
1601 | ||
22cb7405 | 1602 | synchronize_rcu_expedited(); |
48a066e7 | 1603 | |
56cbb429 AV |
1604 | hlist_for_each_entry_safe(m, p, &head, mnt_umount) { |
1605 | hlist_del(&m->mnt_umount); | |
1606 | mntput(&m->mnt); | |
1607 | } | |
70fbcdf4 RP |
1608 | } |
1609 | ||
97216be0 | 1610 | static inline void namespace_lock(void) |
e3197d83 | 1611 | { |
97216be0 | 1612 | down_write(&namespace_sem); |
e3197d83 AV |
1613 | } |
1614 | ||
e819f152 EB |
1615 | enum umount_tree_flags { |
1616 | UMOUNT_SYNC = 1, | |
1617 | UMOUNT_PROPAGATE = 2, | |
e0c9c0af | 1618 | UMOUNT_CONNECTED = 4, |
e819f152 | 1619 | }; |
f2d0a123 EB |
1620 | |
1621 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) | |
1622 | { | |
1623 | /* Leaving mounts connected is only valid for lazy umounts */ | |
1624 | if (how & UMOUNT_SYNC) | |
1625 | return true; | |
1626 | ||
1627 | /* A mount without a parent has nothing to be connected to */ | |
1628 | if (!mnt_has_parent(mnt)) | |
1629 | return true; | |
1630 | ||
1631 | /* Because the reference counting rules change when mounts are | |
1632 | * unmounted and connected, umounted mounts may not be | |
1633 | * connected to mounted mounts. | |
1634 | */ | |
1635 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) | |
1636 | return true; | |
1637 | ||
1638 | /* Has it been requested that the mount remain connected? */ | |
1639 | if (how & UMOUNT_CONNECTED) | |
1640 | return false; | |
1641 | ||
1642 | /* Is the mount locked such that it needs to remain connected? */ | |
1643 | if (IS_MNT_LOCKED(mnt)) | |
1644 | return false; | |
1645 | ||
1646 | /* By default disconnect the mount */ | |
1647 | return true; | |
1648 | } | |
1649 | ||
99b7db7b | 1650 | /* |
48a066e7 | 1651 | * mount_lock must be held |
99b7db7b NP |
1652 | * namespace_sem must be held for write |
1653 | */ | |
e819f152 | 1654 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
1da177e4 | 1655 | { |
c003b26f | 1656 | LIST_HEAD(tmp_list); |
315fc83e | 1657 | struct mount *p; |
1da177e4 | 1658 | |
5d88457e EB |
1659 | if (how & UMOUNT_PROPAGATE) |
1660 | propagate_mount_unlock(mnt); | |
1661 | ||
c003b26f | 1662 | /* Gather the mounts to umount */ |
590ce4bc EB |
1663 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1664 | p->mnt.mnt_flags |= MNT_UMOUNT; | |
c003b26f | 1665 | list_move(&p->mnt_list, &tmp_list); |
590ce4bc | 1666 | } |
1da177e4 | 1667 | |
411a938b | 1668 | /* Hide the mounts from mnt_mounts */ |
c003b26f | 1669 | list_for_each_entry(p, &tmp_list, mnt_list) { |
88b368f2 | 1670 | list_del_init(&p->mnt_child); |
c003b26f | 1671 | } |
88b368f2 | 1672 | |
c003b26f | 1673 | /* Add propogated mounts to the tmp_list */ |
e819f152 | 1674 | if (how & UMOUNT_PROPAGATE) |
7b8a53fd | 1675 | propagate_umount(&tmp_list); |
a05964f3 | 1676 | |
c003b26f | 1677 | while (!list_empty(&tmp_list)) { |
d2921684 | 1678 | struct mnt_namespace *ns; |
ce07d891 | 1679 | bool disconnect; |
c003b26f | 1680 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
6776db3d | 1681 | list_del_init(&p->mnt_expire); |
1a4eeaf2 | 1682 | list_del_init(&p->mnt_list); |
d2921684 EB |
1683 | ns = p->mnt_ns; |
1684 | if (ns) { | |
1685 | ns->mounts--; | |
1686 | __touch_mnt_namespace(ns); | |
1687 | } | |
143c8c91 | 1688 | p->mnt_ns = NULL; |
e819f152 | 1689 | if (how & UMOUNT_SYNC) |
48a066e7 | 1690 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
87b95ce0 | 1691 | |
f2d0a123 | 1692 | disconnect = disconnect_mount(p, how); |
676da58d | 1693 | if (mnt_has_parent(p)) { |
81b6b061 | 1694 | mnt_add_count(p->mnt_parent, -1); |
ce07d891 EB |
1695 | if (!disconnect) { |
1696 | /* Don't forget about p */ | |
1697 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); | |
1698 | } else { | |
1699 | umount_mnt(p); | |
1700 | } | |
7c4b93d8 | 1701 | } |
0f0afb1d | 1702 | change_mnt_propagation(p, MS_PRIVATE); |
19a1c409 AV |
1703 | if (disconnect) |
1704 | hlist_add_head(&p->mnt_umount, &unmounted); | |
1da177e4 LT |
1705 | } |
1706 | } | |
1707 | ||
b54b9be7 | 1708 | static void shrink_submounts(struct mount *mnt); |
c35038be | 1709 | |
8d0347f6 DH |
1710 | static int do_umount_root(struct super_block *sb) |
1711 | { | |
1712 | int ret = 0; | |
1713 | ||
1714 | down_write(&sb->s_umount); | |
1715 | if (!sb_rdonly(sb)) { | |
1716 | struct fs_context *fc; | |
1717 | ||
1718 | fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY, | |
1719 | SB_RDONLY); | |
1720 | if (IS_ERR(fc)) { | |
1721 | ret = PTR_ERR(fc); | |
1722 | } else { | |
1723 | ret = parse_monolithic_mount_data(fc, NULL); | |
1724 | if (!ret) | |
1725 | ret = reconfigure_super(fc); | |
1726 | put_fs_context(fc); | |
1727 | } | |
1728 | } | |
1729 | up_write(&sb->s_umount); | |
1730 | return ret; | |
1731 | } | |
1732 | ||
1ab59738 | 1733 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1734 | { |
1ab59738 | 1735 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 LT |
1736 | int retval; |
1737 | ||
1ab59738 | 1738 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1739 | if (retval) |
1740 | return retval; | |
1741 | ||
1742 | /* | |
1743 | * Allow userspace to request a mountpoint be expired rather than | |
1744 | * unmounting unconditionally. Unmount only happens if: | |
1745 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1746 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1747 | */ | |
1748 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1749 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1750 | flags & (MNT_FORCE | MNT_DETACH)) |
1751 | return -EINVAL; | |
1752 | ||
b3e19d92 NP |
1753 | /* |
1754 | * probably don't strictly need the lock here if we examined | |
1755 | * all race cases, but it's a slowpath. | |
1756 | */ | |
719ea2fb | 1757 | lock_mount_hash(); |
83adc753 | 1758 | if (mnt_get_count(mnt) != 2) { |
719ea2fb | 1759 | unlock_mount_hash(); |
1da177e4 | 1760 | return -EBUSY; |
b3e19d92 | 1761 | } |
719ea2fb | 1762 | unlock_mount_hash(); |
1da177e4 | 1763 | |
863d684f | 1764 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
1da177e4 LT |
1765 | return -EAGAIN; |
1766 | } | |
1767 | ||
1768 | /* | |
1769 | * If we may have to abort operations to get out of this | |
1770 | * mount, and they will themselves hold resources we must | |
1771 | * allow the fs to do things. In the Unix tradition of | |
1772 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1773 | * might fail to complete on the first run through as other tasks | |
1774 | * must return, and the like. Thats for the mount program to worry | |
1775 | * about for the moment. | |
1776 | */ | |
1777 | ||
42faad99 | 1778 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1779 | sb->s_op->umount_begin(sb); |
42faad99 | 1780 | } |
1da177e4 LT |
1781 | |
1782 | /* | |
1783 | * No sense to grab the lock for this test, but test itself looks | |
1784 | * somewhat bogus. Suggestions for better replacement? | |
1785 | * Ho-hum... In principle, we might treat that as umount + switch | |
1786 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1787 | * Actually it makes sense, especially if rootfs would contain a | |
1788 | * /reboot - static binary that would close all descriptors and | |
1789 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1790 | */ | |
1ab59738 | 1791 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1792 | /* |
1793 | * Special case for "unmounting" root ... | |
1794 | * we just try to remount it readonly. | |
1795 | */ | |
bc6155d1 | 1796 | if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) |
a1480dcc | 1797 | return -EPERM; |
8d0347f6 | 1798 | return do_umount_root(sb); |
1da177e4 LT |
1799 | } |
1800 | ||
97216be0 | 1801 | namespace_lock(); |
719ea2fb | 1802 | lock_mount_hash(); |
1da177e4 | 1803 | |
25d202ed EB |
1804 | /* Recheck MNT_LOCKED with the locks held */ |
1805 | retval = -EINVAL; | |
1806 | if (mnt->mnt.mnt_flags & MNT_LOCKED) | |
1807 | goto out; | |
1808 | ||
1809 | event++; | |
48a066e7 | 1810 | if (flags & MNT_DETACH) { |
1a4eeaf2 | 1811 | if (!list_empty(&mnt->mnt_list)) |
e819f152 | 1812 | umount_tree(mnt, UMOUNT_PROPAGATE); |
1da177e4 | 1813 | retval = 0; |
48a066e7 AV |
1814 | } else { |
1815 | shrink_submounts(mnt); | |
1816 | retval = -EBUSY; | |
1817 | if (!propagate_mount_busy(mnt, 2)) { | |
1818 | if (!list_empty(&mnt->mnt_list)) | |
e819f152 | 1819 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
48a066e7 AV |
1820 | retval = 0; |
1821 | } | |
1da177e4 | 1822 | } |
25d202ed | 1823 | out: |
719ea2fb | 1824 | unlock_mount_hash(); |
e3197d83 | 1825 | namespace_unlock(); |
1da177e4 LT |
1826 | return retval; |
1827 | } | |
1828 | ||
80b5dce8 EB |
1829 | /* |
1830 | * __detach_mounts - lazily unmount all mounts on the specified dentry | |
1831 | * | |
1832 | * During unlink, rmdir, and d_drop it is possible to loose the path | |
1833 | * to an existing mountpoint, and wind up leaking the mount. | |
1834 | * detach_mounts allows lazily unmounting those mounts instead of | |
1835 | * leaking them. | |
1836 | * | |
1837 | * The caller may hold dentry->d_inode->i_mutex. | |
1838 | */ | |
1839 | void __detach_mounts(struct dentry *dentry) | |
1840 | { | |
1841 | struct mountpoint *mp; | |
1842 | struct mount *mnt; | |
1843 | ||
1844 | namespace_lock(); | |
3895dbf8 | 1845 | lock_mount_hash(); |
80b5dce8 | 1846 | mp = lookup_mountpoint(dentry); |
adc9b5c0 | 1847 | if (!mp) |
80b5dce8 EB |
1848 | goto out_unlock; |
1849 | ||
e06b933e | 1850 | event++; |
80b5dce8 EB |
1851 | while (!hlist_empty(&mp->m_list)) { |
1852 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); | |
ce07d891 | 1853 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
fe78fcc8 | 1854 | umount_mnt(mnt); |
56cbb429 | 1855 | hlist_add_head(&mnt->mnt_umount, &unmounted); |
ce07d891 | 1856 | } |
e0c9c0af | 1857 | else umount_tree(mnt, UMOUNT_CONNECTED); |
80b5dce8 | 1858 | } |
80b5dce8 EB |
1859 | put_mountpoint(mp); |
1860 | out_unlock: | |
3895dbf8 | 1861 | unlock_mount_hash(); |
80b5dce8 EB |
1862 | namespace_unlock(); |
1863 | } | |
1864 | ||
dd111b31 | 1865 | /* |
9b40bc90 AV |
1866 | * Is the caller allowed to modify his namespace? |
1867 | */ | |
a5f85d78 | 1868 | bool may_mount(void) |
9b40bc90 AV |
1869 | { |
1870 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); | |
1871 | } | |
1872 | ||
f7e33bdb | 1873 | static void warn_mandlock(void) |
9e8925b6 | 1874 | { |
f7e33bdb JL |
1875 | pr_warn_once("=======================================================\n" |
1876 | "WARNING: The mand mount option has been deprecated and\n" | |
1877 | " and is ignored by this kernel. Remove the mand\n" | |
1878 | " option from the mount to silence this warning.\n" | |
1879 | "=======================================================\n"); | |
9e8925b6 JL |
1880 | } |
1881 | ||
25ccd24f | 1882 | static int can_umount(const struct path *path, int flags) |
1da177e4 | 1883 | { |
25ccd24f | 1884 | struct mount *mnt = real_mount(path->mnt); |
1da177e4 | 1885 | |
9b40bc90 AV |
1886 | if (!may_mount()) |
1887 | return -EPERM; | |
41525f56 | 1888 | if (path->dentry != path->mnt->mnt_root) |
25ccd24f | 1889 | return -EINVAL; |
143c8c91 | 1890 | if (!check_mnt(mnt)) |
25ccd24f | 1891 | return -EINVAL; |
25d202ed | 1892 | if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ |
25ccd24f | 1893 | return -EINVAL; |
b2f5d4dc | 1894 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
25ccd24f CH |
1895 | return -EPERM; |
1896 | return 0; | |
1897 | } | |
1898 | ||
a0a6df9a | 1899 | // caller is responsible for flags being sane |
25ccd24f CH |
1900 | int path_umount(struct path *path, int flags) |
1901 | { | |
1902 | struct mount *mnt = real_mount(path->mnt); | |
1903 | int ret; | |
1904 | ||
1905 | ret = can_umount(path, flags); | |
1906 | if (!ret) | |
1907 | ret = do_umount(mnt, flags); | |
1da177e4 | 1908 | |
429731b1 | 1909 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
41525f56 | 1910 | dput(path->dentry); |
900148dc | 1911 | mntput_no_expire(mnt); |
25ccd24f | 1912 | return ret; |
1da177e4 LT |
1913 | } |
1914 | ||
09267def | 1915 | static int ksys_umount(char __user *name, int flags) |
41525f56 CH |
1916 | { |
1917 | int lookup_flags = LOOKUP_MOUNTPOINT; | |
1918 | struct path path; | |
1919 | int ret; | |
1920 | ||
a0a6df9a AV |
1921 | // basic validity checks done first |
1922 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) | |
1923 | return -EINVAL; | |
1924 | ||
41525f56 CH |
1925 | if (!(flags & UMOUNT_NOFOLLOW)) |
1926 | lookup_flags |= LOOKUP_FOLLOW; | |
1927 | ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); | |
1928 | if (ret) | |
1929 | return ret; | |
1930 | return path_umount(&path, flags); | |
1931 | } | |
1932 | ||
3a18ef5c DB |
1933 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1934 | { | |
1935 | return ksys_umount(name, flags); | |
1936 | } | |
1937 | ||
1da177e4 LT |
1938 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
1939 | ||
1940 | /* | |
b58fed8b | 1941 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1942 | */ |
bdc480e3 | 1943 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1944 | { |
3a18ef5c | 1945 | return ksys_umount(name, 0); |
1da177e4 LT |
1946 | } |
1947 | ||
1948 | #endif | |
1949 | ||
4ce5d2b1 | 1950 | static bool is_mnt_ns_file(struct dentry *dentry) |
8823c079 | 1951 | { |
4ce5d2b1 | 1952 | /* Is this a proxy for a mount namespace? */ |
e149ed2b AV |
1953 | return dentry->d_op == &ns_dentry_operations && |
1954 | dentry->d_fsdata == &mntns_operations; | |
4ce5d2b1 EB |
1955 | } |
1956 | ||
213921f9 | 1957 | static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
58be2825 AV |
1958 | { |
1959 | return container_of(ns, struct mnt_namespace, ns); | |
1960 | } | |
1961 | ||
303cc571 CB |
1962 | struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) |
1963 | { | |
1964 | return &mnt->ns; | |
1965 | } | |
1966 | ||
4ce5d2b1 EB |
1967 | static bool mnt_ns_loop(struct dentry *dentry) |
1968 | { | |
1969 | /* Could bind mounting the mount namespace inode cause a | |
1970 | * mount namespace loop? | |
1971 | */ | |
1972 | struct mnt_namespace *mnt_ns; | |
1973 | if (!is_mnt_ns_file(dentry)) | |
1974 | return false; | |
1975 | ||
f77c8014 | 1976 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
8823c079 EB |
1977 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
1978 | } | |
1979 | ||
87129cc0 | 1980 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1981 | int flag) |
1da177e4 | 1982 | { |
84d17192 | 1983 | struct mount *res, *p, *q, *r, *parent; |
1da177e4 | 1984 | |
4ce5d2b1 EB |
1985 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
1986 | return ERR_PTR(-EINVAL); | |
1987 | ||
1988 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) | |
be34d1a3 | 1989 | return ERR_PTR(-EINVAL); |
9676f0c6 | 1990 | |
36341f64 | 1991 | res = q = clone_mnt(mnt, dentry, flag); |
be34d1a3 DH |
1992 | if (IS_ERR(q)) |
1993 | return q; | |
1994 | ||
a73324da | 1995 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1996 | |
1997 | p = mnt; | |
6b41d536 | 1998 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1999 | struct mount *s; |
7ec02ef1 | 2000 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
2001 | continue; |
2002 | ||
909b0a88 | 2003 | for (s = r; s; s = next_mnt(s, r)) { |
4ce5d2b1 EB |
2004 | if (!(flag & CL_COPY_UNBINDABLE) && |
2005 | IS_MNT_UNBINDABLE(s)) { | |
df7342b2 EB |
2006 | if (s->mnt.mnt_flags & MNT_LOCKED) { |
2007 | /* Both unbindable and locked. */ | |
2008 | q = ERR_PTR(-EPERM); | |
2009 | goto out; | |
2010 | } else { | |
2011 | s = skip_mnt_tree(s); | |
2012 | continue; | |
2013 | } | |
4ce5d2b1 EB |
2014 | } |
2015 | if (!(flag & CL_COPY_MNT_NS_FILE) && | |
2016 | is_mnt_ns_file(s->mnt.mnt_root)) { | |
9676f0c6 RP |
2017 | s = skip_mnt_tree(s); |
2018 | continue; | |
2019 | } | |
0714a533 AV |
2020 | while (p != s->mnt_parent) { |
2021 | p = p->mnt_parent; | |
2022 | q = q->mnt_parent; | |
1da177e4 | 2023 | } |
87129cc0 | 2024 | p = s; |
84d17192 | 2025 | parent = q; |
87129cc0 | 2026 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
be34d1a3 DH |
2027 | if (IS_ERR(q)) |
2028 | goto out; | |
719ea2fb | 2029 | lock_mount_hash(); |
1a4eeaf2 | 2030 | list_add_tail(&q->mnt_list, &res->mnt_list); |
1064f874 | 2031 | attach_mnt(q, parent, p->mnt_mp); |
719ea2fb | 2032 | unlock_mount_hash(); |
1da177e4 LT |
2033 | } |
2034 | } | |
2035 | return res; | |
be34d1a3 | 2036 | out: |
1da177e4 | 2037 | if (res) { |
719ea2fb | 2038 | lock_mount_hash(); |
e819f152 | 2039 | umount_tree(res, UMOUNT_SYNC); |
719ea2fb | 2040 | unlock_mount_hash(); |
1da177e4 | 2041 | } |
be34d1a3 | 2042 | return q; |
1da177e4 LT |
2043 | } |
2044 | ||
be34d1a3 DH |
2045 | /* Caller should check returned pointer for errors */ |
2046 | ||
ca71cf71 | 2047 | struct vfsmount *collect_mounts(const struct path *path) |
8aec0809 | 2048 | { |
cb338d06 | 2049 | struct mount *tree; |
97216be0 | 2050 | namespace_lock(); |
cd4a4017 EB |
2051 | if (!check_mnt(real_mount(path->mnt))) |
2052 | tree = ERR_PTR(-EINVAL); | |
2053 | else | |
2054 | tree = copy_tree(real_mount(path->mnt), path->dentry, | |
2055 | CL_COPY_ALL | CL_PRIVATE); | |
328e6d90 | 2056 | namespace_unlock(); |
be34d1a3 | 2057 | if (IS_ERR(tree)) |
52e220d3 | 2058 | return ERR_CAST(tree); |
be34d1a3 | 2059 | return &tree->mnt; |
8aec0809 AV |
2060 | } |
2061 | ||
a07b2000 AV |
2062 | static void free_mnt_ns(struct mnt_namespace *); |
2063 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool); | |
2064 | ||
2065 | void dissolve_on_fput(struct vfsmount *mnt) | |
2066 | { | |
2067 | struct mnt_namespace *ns; | |
2068 | namespace_lock(); | |
2069 | lock_mount_hash(); | |
2070 | ns = real_mount(mnt)->mnt_ns; | |
44dfd84a DH |
2071 | if (ns) { |
2072 | if (is_anon_ns(ns)) | |
2073 | umount_tree(real_mount(mnt), UMOUNT_CONNECTED); | |
2074 | else | |
2075 | ns = NULL; | |
2076 | } | |
a07b2000 AV |
2077 | unlock_mount_hash(); |
2078 | namespace_unlock(); | |
44dfd84a DH |
2079 | if (ns) |
2080 | free_mnt_ns(ns); | |
a07b2000 AV |
2081 | } |
2082 | ||
8aec0809 AV |
2083 | void drop_collected_mounts(struct vfsmount *mnt) |
2084 | { | |
97216be0 | 2085 | namespace_lock(); |
719ea2fb | 2086 | lock_mount_hash(); |
9c8e0a1b | 2087 | umount_tree(real_mount(mnt), 0); |
719ea2fb | 2088 | unlock_mount_hash(); |
3ab6abee | 2089 | namespace_unlock(); |
8aec0809 AV |
2090 | } |
2091 | ||
427215d8 MS |
2092 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
2093 | { | |
2094 | struct mount *child; | |
2095 | ||
2096 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
2097 | if (!is_subdir(child->mnt_mountpoint, dentry)) | |
2098 | continue; | |
2099 | ||
2100 | if (child->mnt.mnt_flags & MNT_LOCKED) | |
2101 | return true; | |
2102 | } | |
2103 | return false; | |
2104 | } | |
2105 | ||
c771d683 MS |
2106 | /** |
2107 | * clone_private_mount - create a private clone of a path | |
1f287bc4 | 2108 | * @path: path to clone |
c771d683 | 2109 | * |
1f287bc4 RD |
2110 | * This creates a new vfsmount, which will be the clone of @path. The new mount |
2111 | * will not be attached anywhere in the namespace and will be private (i.e. | |
2112 | * changes to the originating mount won't be propagated into this). | |
c771d683 MS |
2113 | * |
2114 | * Release with mntput(). | |
2115 | */ | |
ca71cf71 | 2116 | struct vfsmount *clone_private_mount(const struct path *path) |
c771d683 MS |
2117 | { |
2118 | struct mount *old_mnt = real_mount(path->mnt); | |
2119 | struct mount *new_mnt; | |
2120 | ||
427215d8 | 2121 | down_read(&namespace_sem); |
c771d683 | 2122 | if (IS_MNT_UNBINDABLE(old_mnt)) |
427215d8 MS |
2123 | goto invalid; |
2124 | ||
2125 | if (!check_mnt(old_mnt)) | |
2126 | goto invalid; | |
2127 | ||
2128 | if (has_locked_children(old_mnt, path->dentry)) | |
2129 | goto invalid; | |
c771d683 | 2130 | |
c771d683 | 2131 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
427215d8 MS |
2132 | up_read(&namespace_sem); |
2133 | ||
c771d683 MS |
2134 | if (IS_ERR(new_mnt)) |
2135 | return ERR_CAST(new_mnt); | |
2136 | ||
df820f8d MS |
2137 | /* Longterm mount to be removed by kern_unmount*() */ |
2138 | new_mnt->mnt_ns = MNT_NS_INTERNAL; | |
2139 | ||
c771d683 | 2140 | return &new_mnt->mnt; |
427215d8 MS |
2141 | |
2142 | invalid: | |
2143 | up_read(&namespace_sem); | |
2144 | return ERR_PTR(-EINVAL); | |
c771d683 MS |
2145 | } |
2146 | EXPORT_SYMBOL_GPL(clone_private_mount); | |
2147 | ||
1f707137 AV |
2148 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
2149 | struct vfsmount *root) | |
2150 | { | |
1a4eeaf2 | 2151 | struct mount *mnt; |
1f707137 AV |
2152 | int res = f(root, arg); |
2153 | if (res) | |
2154 | return res; | |
1a4eeaf2 AV |
2155 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
2156 | res = f(&mnt->mnt, arg); | |
1f707137 AV |
2157 | if (res) |
2158 | return res; | |
2159 | } | |
2160 | return 0; | |
2161 | } | |
2162 | ||
3bd045cc AV |
2163 | static void lock_mnt_tree(struct mount *mnt) |
2164 | { | |
2165 | struct mount *p; | |
2166 | ||
2167 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
2168 | int flags = p->mnt.mnt_flags; | |
2169 | /* Don't allow unprivileged users to change mount flags */ | |
2170 | flags |= MNT_LOCK_ATIME; | |
2171 | ||
2172 | if (flags & MNT_READONLY) | |
2173 | flags |= MNT_LOCK_READONLY; | |
2174 | ||
2175 | if (flags & MNT_NODEV) | |
2176 | flags |= MNT_LOCK_NODEV; | |
2177 | ||
2178 | if (flags & MNT_NOSUID) | |
2179 | flags |= MNT_LOCK_NOSUID; | |
2180 | ||
2181 | if (flags & MNT_NOEXEC) | |
2182 | flags |= MNT_LOCK_NOEXEC; | |
2183 | /* Don't allow unprivileged users to reveal what is under a mount */ | |
2184 | if (list_empty(&p->mnt_expire)) | |
2185 | flags |= MNT_LOCKED; | |
2186 | p->mnt.mnt_flags = flags; | |
2187 | } | |
2188 | } | |
2189 | ||
4b8b21f4 | 2190 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 2191 | { |
315fc83e | 2192 | struct mount *p; |
719f5d7f | 2193 | |
909b0a88 | 2194 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
fc7be130 | 2195 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
4b8b21f4 | 2196 | mnt_release_group_id(p); |
719f5d7f MS |
2197 | } |
2198 | } | |
2199 | ||
4b8b21f4 | 2200 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 2201 | { |
315fc83e | 2202 | struct mount *p; |
719f5d7f | 2203 | |
909b0a88 | 2204 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
fc7be130 | 2205 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
4b8b21f4 | 2206 | int err = mnt_alloc_group_id(p); |
719f5d7f | 2207 | if (err) { |
4b8b21f4 | 2208 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
2209 | return err; |
2210 | } | |
2211 | } | |
2212 | } | |
2213 | ||
2214 | return 0; | |
2215 | } | |
2216 | ||
d2921684 EB |
2217 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
2218 | { | |
2219 | unsigned int max = READ_ONCE(sysctl_mount_max); | |
124f75f8 | 2220 | unsigned int mounts = 0; |
d2921684 EB |
2221 | struct mount *p; |
2222 | ||
124f75f8 AV |
2223 | if (ns->mounts >= max) |
2224 | return -ENOSPC; | |
2225 | max -= ns->mounts; | |
2226 | if (ns->pending_mounts >= max) | |
2227 | return -ENOSPC; | |
2228 | max -= ns->pending_mounts; | |
2229 | ||
d2921684 EB |
2230 | for (p = mnt; p; p = next_mnt(p, mnt)) |
2231 | mounts++; | |
2232 | ||
124f75f8 | 2233 | if (mounts > max) |
d2921684 EB |
2234 | return -ENOSPC; |
2235 | ||
124f75f8 | 2236 | ns->pending_mounts += mounts; |
d2921684 EB |
2237 | return 0; |
2238 | } | |
2239 | ||
b90fa9ae RP |
2240 | /* |
2241 | * @source_mnt : mount tree to be attached | |
21444403 RP |
2242 | * @nd : place the mount tree @source_mnt is attached |
2243 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
2244 | * store the parent mount and mountpoint dentry. | |
2245 | * (done when source_mnt is moved) | |
b90fa9ae RP |
2246 | * |
2247 | * NOTE: in the table below explains the semantics when a source mount | |
2248 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
2249 | * --------------------------------------------------------------------------- |
2250 | * | BIND MOUNT OPERATION | | |
2251 | * |************************************************************************** | |
2252 | * | source-->| shared | private | slave | unbindable | | |
2253 | * | dest | | | | | | |
2254 | * | | | | | | | | |
2255 | * | v | | | | | | |
2256 | * |************************************************************************** | |
2257 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
2258 | * | | | | | | | |
2259 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
2260 | * *************************************************************************** | |
b90fa9ae RP |
2261 | * A bind operation clones the source mount and mounts the clone on the |
2262 | * destination mount. | |
2263 | * | |
2264 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
2265 | * tree of the destination mount and the cloned mount is added to | |
2266 | * the peer group of the source mount. | |
2267 | * (+) the cloned mount is created under the destination mount and is marked | |
2268 | * as shared. The cloned mount is added to the peer group of the source | |
2269 | * mount. | |
5afe0022 RP |
2270 | * (+++) the mount is propagated to all the mounts in the propagation tree |
2271 | * of the destination mount and the cloned mount is made slave | |
2272 | * of the same master as that of the source mount. The cloned mount | |
2273 | * is marked as 'shared and slave'. | |
2274 | * (*) the cloned mount is made a slave of the same master as that of the | |
2275 | * source mount. | |
2276 | * | |
9676f0c6 RP |
2277 | * --------------------------------------------------------------------------- |
2278 | * | MOVE MOUNT OPERATION | | |
2279 | * |************************************************************************** | |
2280 | * | source-->| shared | private | slave | unbindable | | |
2281 | * | dest | | | | | | |
2282 | * | | | | | | | | |
2283 | * | v | | | | | | |
2284 | * |************************************************************************** | |
2285 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
2286 | * | | | | | | | |
2287 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
2288 | * *************************************************************************** | |
5afe0022 RP |
2289 | * |
2290 | * (+) the mount is moved to the destination. And is then propagated to | |
2291 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 2292 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
2293 | * (+++) the mount is moved to the destination and is then propagated to |
2294 | * all the mounts belonging to the destination mount's propagation tree. | |
2295 | * the mount is marked as 'shared and slave'. | |
2296 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
2297 | * |
2298 | * if the source mount is a tree, the operations explained above is | |
2299 | * applied to each mount in the tree. | |
2300 | * Must be called without spinlocks held, since this function can sleep | |
2301 | * in allocations. | |
2302 | */ | |
0fb54e50 | 2303 | static int attach_recursive_mnt(struct mount *source_mnt, |
84d17192 AV |
2304 | struct mount *dest_mnt, |
2305 | struct mountpoint *dest_mp, | |
2763d119 | 2306 | bool moving) |
b90fa9ae | 2307 | { |
3bd045cc | 2308 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
38129a13 | 2309 | HLIST_HEAD(tree_list); |
d2921684 | 2310 | struct mnt_namespace *ns = dest_mnt->mnt_ns; |
1064f874 | 2311 | struct mountpoint *smp; |
315fc83e | 2312 | struct mount *child, *p; |
38129a13 | 2313 | struct hlist_node *n; |
719f5d7f | 2314 | int err; |
b90fa9ae | 2315 | |
1064f874 EB |
2316 | /* Preallocate a mountpoint in case the new mounts need |
2317 | * to be tucked under other mounts. | |
2318 | */ | |
2319 | smp = get_mountpoint(source_mnt->mnt.mnt_root); | |
2320 | if (IS_ERR(smp)) | |
2321 | return PTR_ERR(smp); | |
2322 | ||
d2921684 | 2323 | /* Is there space to add these mounts to the mount namespace? */ |
2763d119 | 2324 | if (!moving) { |
d2921684 EB |
2325 | err = count_mounts(ns, source_mnt); |
2326 | if (err) | |
2327 | goto out; | |
2328 | } | |
2329 | ||
fc7be130 | 2330 | if (IS_MNT_SHARED(dest_mnt)) { |
0fb54e50 | 2331 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
2332 | if (err) |
2333 | goto out; | |
0b1b901b | 2334 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
f2ebb3a9 | 2335 | lock_mount_hash(); |
0b1b901b AV |
2336 | if (err) |
2337 | goto out_cleanup_ids; | |
909b0a88 | 2338 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
0f0afb1d | 2339 | set_mnt_shared(p); |
0b1b901b AV |
2340 | } else { |
2341 | lock_mount_hash(); | |
b90fa9ae | 2342 | } |
2763d119 AV |
2343 | if (moving) { |
2344 | unhash_mnt(source_mnt); | |
84d17192 | 2345 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
143c8c91 | 2346 | touch_mnt_namespace(source_mnt->mnt_ns); |
21444403 | 2347 | } else { |
44dfd84a DH |
2348 | if (source_mnt->mnt_ns) { |
2349 | /* move from anon - the caller will destroy */ | |
2350 | list_del_init(&source_mnt->mnt_ns->list); | |
2351 | } | |
84d17192 | 2352 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
1064f874 | 2353 | commit_tree(source_mnt); |
21444403 | 2354 | } |
b90fa9ae | 2355 | |
38129a13 | 2356 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
1d6a32ac | 2357 | struct mount *q; |
38129a13 | 2358 | hlist_del_init(&child->mnt_hash); |
1064f874 EB |
2359 | q = __lookup_mnt(&child->mnt_parent->mnt, |
2360 | child->mnt_mountpoint); | |
2361 | if (q) | |
2362 | mnt_change_mountpoint(child, smp, q); | |
3bd045cc AV |
2363 | /* Notice when we are propagating across user namespaces */ |
2364 | if (child->mnt_parent->mnt_ns->user_ns != user_ns) | |
2365 | lock_mnt_tree(child); | |
d728cf79 | 2366 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
1064f874 | 2367 | commit_tree(child); |
b90fa9ae | 2368 | } |
1064f874 | 2369 | put_mountpoint(smp); |
719ea2fb | 2370 | unlock_mount_hash(); |
99b7db7b | 2371 | |
b90fa9ae | 2372 | return 0; |
719f5d7f MS |
2373 | |
2374 | out_cleanup_ids: | |
f2ebb3a9 AV |
2375 | while (!hlist_empty(&tree_list)) { |
2376 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); | |
d2921684 | 2377 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
e819f152 | 2378 | umount_tree(child, UMOUNT_SYNC); |
f2ebb3a9 AV |
2379 | } |
2380 | unlock_mount_hash(); | |
0b1b901b | 2381 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f | 2382 | out: |
d2921684 | 2383 | ns->pending_mounts = 0; |
1064f874 EB |
2384 | |
2385 | read_seqlock_excl(&mount_lock); | |
2386 | put_mountpoint(smp); | |
2387 | read_sequnlock_excl(&mount_lock); | |
2388 | ||
719f5d7f | 2389 | return err; |
b90fa9ae RP |
2390 | } |
2391 | ||
84d17192 | 2392 | static struct mountpoint *lock_mount(struct path *path) |
b12cea91 AV |
2393 | { |
2394 | struct vfsmount *mnt; | |
84d17192 | 2395 | struct dentry *dentry = path->dentry; |
b12cea91 | 2396 | retry: |
5955102c | 2397 | inode_lock(dentry->d_inode); |
84d17192 | 2398 | if (unlikely(cant_mount(dentry))) { |
5955102c | 2399 | inode_unlock(dentry->d_inode); |
84d17192 | 2400 | return ERR_PTR(-ENOENT); |
b12cea91 | 2401 | } |
97216be0 | 2402 | namespace_lock(); |
b12cea91 | 2403 | mnt = lookup_mnt(path); |
84d17192 | 2404 | if (likely(!mnt)) { |
3895dbf8 | 2405 | struct mountpoint *mp = get_mountpoint(dentry); |
84d17192 | 2406 | if (IS_ERR(mp)) { |
97216be0 | 2407 | namespace_unlock(); |
5955102c | 2408 | inode_unlock(dentry->d_inode); |
84d17192 AV |
2409 | return mp; |
2410 | } | |
2411 | return mp; | |
2412 | } | |
97216be0 | 2413 | namespace_unlock(); |
5955102c | 2414 | inode_unlock(path->dentry->d_inode); |
b12cea91 AV |
2415 | path_put(path); |
2416 | path->mnt = mnt; | |
84d17192 | 2417 | dentry = path->dentry = dget(mnt->mnt_root); |
b12cea91 AV |
2418 | goto retry; |
2419 | } | |
2420 | ||
84d17192 | 2421 | static void unlock_mount(struct mountpoint *where) |
b12cea91 | 2422 | { |
84d17192 | 2423 | struct dentry *dentry = where->m_dentry; |
3895dbf8 EB |
2424 | |
2425 | read_seqlock_excl(&mount_lock); | |
84d17192 | 2426 | put_mountpoint(where); |
3895dbf8 EB |
2427 | read_sequnlock_excl(&mount_lock); |
2428 | ||
328e6d90 | 2429 | namespace_unlock(); |
5955102c | 2430 | inode_unlock(dentry->d_inode); |
b12cea91 AV |
2431 | } |
2432 | ||
84d17192 | 2433 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
1da177e4 | 2434 | { |
e462ec50 | 2435 | if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER) |
1da177e4 LT |
2436 | return -EINVAL; |
2437 | ||
e36cb0b8 DH |
2438 | if (d_is_dir(mp->m_dentry) != |
2439 | d_is_dir(mnt->mnt.mnt_root)) | |
1da177e4 LT |
2440 | return -ENOTDIR; |
2441 | ||
2763d119 | 2442 | return attach_recursive_mnt(mnt, p, mp, false); |
1da177e4 LT |
2443 | } |
2444 | ||
7a2e8a8f VA |
2445 | /* |
2446 | * Sanity check the flags to change_mnt_propagation. | |
2447 | */ | |
2448 | ||
e462ec50 | 2449 | static int flags_to_propagation_type(int ms_flags) |
7a2e8a8f | 2450 | { |
e462ec50 | 2451 | int type = ms_flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
2452 | |
2453 | /* Fail if any non-propagation flags are set */ | |
2454 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
2455 | return 0; | |
2456 | /* Only one propagation flag should be set */ | |
2457 | if (!is_power_of_2(type)) | |
2458 | return 0; | |
2459 | return type; | |
2460 | } | |
2461 | ||
07b20889 RP |
2462 | /* |
2463 | * recursively change the type of the mountpoint. | |
2464 | */ | |
e462ec50 | 2465 | static int do_change_type(struct path *path, int ms_flags) |
07b20889 | 2466 | { |
315fc83e | 2467 | struct mount *m; |
4b8b21f4 | 2468 | struct mount *mnt = real_mount(path->mnt); |
e462ec50 | 2469 | int recurse = ms_flags & MS_REC; |
7a2e8a8f | 2470 | int type; |
719f5d7f | 2471 | int err = 0; |
07b20889 | 2472 | |
2d92ab3c | 2473 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
2474 | return -EINVAL; |
2475 | ||
e462ec50 | 2476 | type = flags_to_propagation_type(ms_flags); |
7a2e8a8f VA |
2477 | if (!type) |
2478 | return -EINVAL; | |
2479 | ||
97216be0 | 2480 | namespace_lock(); |
719f5d7f MS |
2481 | if (type == MS_SHARED) { |
2482 | err = invent_group_ids(mnt, recurse); | |
2483 | if (err) | |
2484 | goto out_unlock; | |
2485 | } | |
2486 | ||
719ea2fb | 2487 | lock_mount_hash(); |
909b0a88 | 2488 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
0f0afb1d | 2489 | change_mnt_propagation(m, type); |
719ea2fb | 2490 | unlock_mount_hash(); |
719f5d7f MS |
2491 | |
2492 | out_unlock: | |
97216be0 | 2493 | namespace_unlock(); |
719f5d7f | 2494 | return err; |
07b20889 RP |
2495 | } |
2496 | ||
a07b2000 AV |
2497 | static struct mount *__do_loopback(struct path *old_path, int recurse) |
2498 | { | |
2499 | struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt); | |
2500 | ||
2501 | if (IS_MNT_UNBINDABLE(old)) | |
2502 | return mnt; | |
2503 | ||
2504 | if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) | |
2505 | return mnt; | |
2506 | ||
2507 | if (!recurse && has_locked_children(old, old_path->dentry)) | |
2508 | return mnt; | |
2509 | ||
2510 | if (recurse) | |
2511 | mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE); | |
2512 | else | |
2513 | mnt = clone_mnt(old, old_path->dentry, 0); | |
2514 | ||
2515 | if (!IS_ERR(mnt)) | |
2516 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
2517 | ||
2518 | return mnt; | |
2519 | } | |
2520 | ||
1da177e4 LT |
2521 | /* |
2522 | * do loopback mount. | |
2523 | */ | |
808d4e3c | 2524 | static int do_loopback(struct path *path, const char *old_name, |
2dafe1c4 | 2525 | int recurse) |
1da177e4 | 2526 | { |
2d92ab3c | 2527 | struct path old_path; |
a07b2000 | 2528 | struct mount *mnt = NULL, *parent; |
84d17192 | 2529 | struct mountpoint *mp; |
57eccb83 | 2530 | int err; |
1da177e4 LT |
2531 | if (!old_name || !*old_name) |
2532 | return -EINVAL; | |
815d405c | 2533 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
2534 | if (err) |
2535 | return err; | |
2536 | ||
8823c079 | 2537 | err = -EINVAL; |
4ce5d2b1 | 2538 | if (mnt_ns_loop(old_path.dentry)) |
dd111b31 | 2539 | goto out; |
8823c079 | 2540 | |
84d17192 | 2541 | mp = lock_mount(path); |
a07b2000 AV |
2542 | if (IS_ERR(mp)) { |
2543 | err = PTR_ERR(mp); | |
b12cea91 | 2544 | goto out; |
a07b2000 | 2545 | } |
b12cea91 | 2546 | |
84d17192 | 2547 | parent = real_mount(path->mnt); |
e149ed2b AV |
2548 | if (!check_mnt(parent)) |
2549 | goto out2; | |
2550 | ||
a07b2000 | 2551 | mnt = __do_loopback(&old_path, recurse); |
be34d1a3 DH |
2552 | if (IS_ERR(mnt)) { |
2553 | err = PTR_ERR(mnt); | |
e9c5d8a5 | 2554 | goto out2; |
be34d1a3 | 2555 | } |
ccd48bc7 | 2556 | |
84d17192 | 2557 | err = graft_tree(mnt, parent, mp); |
ccd48bc7 | 2558 | if (err) { |
719ea2fb | 2559 | lock_mount_hash(); |
e819f152 | 2560 | umount_tree(mnt, UMOUNT_SYNC); |
719ea2fb | 2561 | unlock_mount_hash(); |
5b83d2c5 | 2562 | } |
b12cea91 | 2563 | out2: |
84d17192 | 2564 | unlock_mount(mp); |
ccd48bc7 | 2565 | out: |
2d92ab3c | 2566 | path_put(&old_path); |
1da177e4 LT |
2567 | return err; |
2568 | } | |
2569 | ||
a07b2000 AV |
2570 | static struct file *open_detached_copy(struct path *path, bool recursive) |
2571 | { | |
2572 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; | |
2573 | struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true); | |
2574 | struct mount *mnt, *p; | |
2575 | struct file *file; | |
2576 | ||
2577 | if (IS_ERR(ns)) | |
2578 | return ERR_CAST(ns); | |
2579 | ||
2580 | namespace_lock(); | |
2581 | mnt = __do_loopback(path, recursive); | |
2582 | if (IS_ERR(mnt)) { | |
2583 | namespace_unlock(); | |
2584 | free_mnt_ns(ns); | |
2585 | return ERR_CAST(mnt); | |
2586 | } | |
2587 | ||
2588 | lock_mount_hash(); | |
2589 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
2590 | p->mnt_ns = ns; | |
2591 | ns->mounts++; | |
2592 | } | |
2593 | ns->root = mnt; | |
2594 | list_add_tail(&ns->list, &mnt->mnt_list); | |
2595 | mntget(&mnt->mnt); | |
2596 | unlock_mount_hash(); | |
2597 | namespace_unlock(); | |
2598 | ||
2599 | mntput(path->mnt); | |
2600 | path->mnt = &mnt->mnt; | |
2601 | file = dentry_open(path, O_PATH, current_cred()); | |
2602 | if (IS_ERR(file)) | |
2603 | dissolve_on_fput(path->mnt); | |
2604 | else | |
2605 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
2606 | return file; | |
2607 | } | |
2608 | ||
2658ce09 | 2609 | SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags) |
a07b2000 AV |
2610 | { |
2611 | struct file *file; | |
2612 | struct path path; | |
2613 | int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; | |
2614 | bool detached = flags & OPEN_TREE_CLONE; | |
2615 | int error; | |
2616 | int fd; | |
2617 | ||
2618 | BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); | |
2619 | ||
2620 | if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE | | |
2621 | AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE | | |
2622 | OPEN_TREE_CLOEXEC)) | |
2623 | return -EINVAL; | |
2624 | ||
2625 | if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE) | |
2626 | return -EINVAL; | |
2627 | ||
2628 | if (flags & AT_NO_AUTOMOUNT) | |
2629 | lookup_flags &= ~LOOKUP_AUTOMOUNT; | |
2630 | if (flags & AT_SYMLINK_NOFOLLOW) | |
2631 | lookup_flags &= ~LOOKUP_FOLLOW; | |
2632 | if (flags & AT_EMPTY_PATH) | |
2633 | lookup_flags |= LOOKUP_EMPTY; | |
2634 | ||
2635 | if (detached && !may_mount()) | |
2636 | return -EPERM; | |
2637 | ||
2638 | fd = get_unused_fd_flags(flags & O_CLOEXEC); | |
2639 | if (fd < 0) | |
2640 | return fd; | |
2641 | ||
2642 | error = user_path_at(dfd, filename, lookup_flags, &path); | |
2643 | if (unlikely(error)) { | |
2644 | file = ERR_PTR(error); | |
2645 | } else { | |
2646 | if (detached) | |
2647 | file = open_detached_copy(&path, flags & AT_RECURSIVE); | |
2648 | else | |
2649 | file = dentry_open(&path, O_PATH, current_cred()); | |
2650 | path_put(&path); | |
2651 | } | |
2652 | if (IS_ERR(file)) { | |
2653 | put_unused_fd(fd); | |
2654 | return PTR_ERR(file); | |
2655 | } | |
2656 | fd_install(fd, file); | |
2657 | return fd; | |
2658 | } | |
2659 | ||
43f5e655 DH |
2660 | /* |
2661 | * Don't allow locked mount flags to be cleared. | |
2662 | * | |
2663 | * No locks need to be held here while testing the various MNT_LOCK | |
2664 | * flags because those flags can never be cleared once they are set. | |
2665 | */ | |
2666 | static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2667 | { |
43f5e655 DH |
2668 | unsigned int fl = mnt->mnt.mnt_flags; |
2669 | ||
2670 | if ((fl & MNT_LOCK_READONLY) && | |
2671 | !(mnt_flags & MNT_READONLY)) | |
2672 | return false; | |
2673 | ||
2674 | if ((fl & MNT_LOCK_NODEV) && | |
2675 | !(mnt_flags & MNT_NODEV)) | |
2676 | return false; | |
2677 | ||
2678 | if ((fl & MNT_LOCK_NOSUID) && | |
2679 | !(mnt_flags & MNT_NOSUID)) | |
2680 | return false; | |
2681 | ||
2682 | if ((fl & MNT_LOCK_NOEXEC) && | |
2683 | !(mnt_flags & MNT_NOEXEC)) | |
2684 | return false; | |
2685 | ||
2686 | if ((fl & MNT_LOCK_ATIME) && | |
2687 | ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) | |
2688 | return false; | |
2e4b7fcd | 2689 | |
43f5e655 DH |
2690 | return true; |
2691 | } | |
2692 | ||
2693 | static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2694 | { |
43f5e655 | 2695 | bool readonly_request = (mnt_flags & MNT_READONLY); |
2e4b7fcd | 2696 | |
43f5e655 | 2697 | if (readonly_request == __mnt_is_readonly(&mnt->mnt)) |
2e4b7fcd DH |
2698 | return 0; |
2699 | ||
2700 | if (readonly_request) | |
43f5e655 DH |
2701 | return mnt_make_readonly(mnt); |
2702 | ||
68847c94 CB |
2703 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
2704 | return 0; | |
43f5e655 DH |
2705 | } |
2706 | ||
43f5e655 DH |
2707 | static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) |
2708 | { | |
43f5e655 DH |
2709 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
2710 | mnt->mnt.mnt_flags = mnt_flags; | |
2711 | touch_mnt_namespace(mnt->mnt_ns); | |
43f5e655 DH |
2712 | } |
2713 | ||
f8b92ba6 DD |
2714 | static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt) |
2715 | { | |
2716 | struct super_block *sb = mnt->mnt_sb; | |
2717 | ||
2718 | if (!__mnt_is_readonly(mnt) && | |
a128b054 | 2719 | (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) && |
f8b92ba6 DD |
2720 | (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { |
2721 | char *buf = (char *)__get_free_page(GFP_KERNEL); | |
2722 | char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM); | |
2723 | struct tm tm; | |
2724 | ||
2725 | time64_to_tm(sb->s_time_max, 0, &tm); | |
2726 | ||
0ecee669 EB |
2727 | pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n", |
2728 | sb->s_type->name, | |
2729 | is_mounted(mnt) ? "remounted" : "mounted", | |
2730 | mntpath, | |
f8b92ba6 DD |
2731 | tm.tm_year+1900, (unsigned long long)sb->s_time_max); |
2732 | ||
2733 | free_page((unsigned long)buf); | |
a128b054 | 2734 | sb->s_iflags |= SB_I_TS_EXPIRY_WARNED; |
f8b92ba6 DD |
2735 | } |
2736 | } | |
2737 | ||
43f5e655 DH |
2738 | /* |
2739 | * Handle reconfiguration of the mountpoint only without alteration of the | |
2740 | * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND | |
2741 | * to mount(2). | |
2742 | */ | |
2743 | static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags) | |
2744 | { | |
2745 | struct super_block *sb = path->mnt->mnt_sb; | |
2746 | struct mount *mnt = real_mount(path->mnt); | |
2747 | int ret; | |
2748 | ||
2749 | if (!check_mnt(mnt)) | |
2750 | return -EINVAL; | |
2751 | ||
2752 | if (path->dentry != mnt->mnt.mnt_root) | |
2753 | return -EINVAL; | |
2754 | ||
2755 | if (!can_change_locked_flags(mnt, mnt_flags)) | |
2756 | return -EPERM; | |
2757 | ||
e58ace1a CB |
2758 | /* |
2759 | * We're only checking whether the superblock is read-only not | |
2760 | * changing it, so only take down_read(&sb->s_umount). | |
2761 | */ | |
2762 | down_read(&sb->s_umount); | |
68847c94 | 2763 | lock_mount_hash(); |
43f5e655 DH |
2764 | ret = change_mount_ro_state(mnt, mnt_flags); |
2765 | if (ret == 0) | |
2766 | set_mount_attributes(mnt, mnt_flags); | |
68847c94 | 2767 | unlock_mount_hash(); |
e58ace1a | 2768 | up_read(&sb->s_umount); |
f8b92ba6 DD |
2769 | |
2770 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2771 | ||
43f5e655 | 2772 | return ret; |
2e4b7fcd DH |
2773 | } |
2774 | ||
1da177e4 LT |
2775 | /* |
2776 | * change filesystem flags. dir should be a physical root of filesystem. | |
2777 | * If you've mounted a non-root directory somewhere and want to do remount | |
2778 | * on it - tough luck. | |
2779 | */ | |
e462ec50 DH |
2780 | static int do_remount(struct path *path, int ms_flags, int sb_flags, |
2781 | int mnt_flags, void *data) | |
1da177e4 LT |
2782 | { |
2783 | int err; | |
2d92ab3c | 2784 | struct super_block *sb = path->mnt->mnt_sb; |
143c8c91 | 2785 | struct mount *mnt = real_mount(path->mnt); |
8d0347f6 | 2786 | struct fs_context *fc; |
1da177e4 | 2787 | |
143c8c91 | 2788 | if (!check_mnt(mnt)) |
1da177e4 LT |
2789 | return -EINVAL; |
2790 | ||
2d92ab3c | 2791 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
2792 | return -EINVAL; |
2793 | ||
43f5e655 | 2794 | if (!can_change_locked_flags(mnt, mnt_flags)) |
9566d674 | 2795 | return -EPERM; |
9566d674 | 2796 | |
8d0347f6 DH |
2797 | fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK); |
2798 | if (IS_ERR(fc)) | |
2799 | return PTR_ERR(fc); | |
ff36fe2c | 2800 | |
b330966f | 2801 | fc->oldapi = true; |
8d0347f6 DH |
2802 | err = parse_monolithic_mount_data(fc, data); |
2803 | if (!err) { | |
2804 | down_write(&sb->s_umount); | |
2805 | err = -EPERM; | |
2806 | if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { | |
2807 | err = reconfigure_super(fc); | |
68847c94 CB |
2808 | if (!err) { |
2809 | lock_mount_hash(); | |
8d0347f6 | 2810 | set_mount_attributes(mnt, mnt_flags); |
68847c94 CB |
2811 | unlock_mount_hash(); |
2812 | } | |
8d0347f6 DH |
2813 | } |
2814 | up_write(&sb->s_umount); | |
0e55a7cc | 2815 | } |
f8b92ba6 DD |
2816 | |
2817 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2818 | ||
8d0347f6 | 2819 | put_fs_context(fc); |
1da177e4 LT |
2820 | return err; |
2821 | } | |
2822 | ||
cbbe362c | 2823 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 2824 | { |
315fc83e | 2825 | struct mount *p; |
909b0a88 | 2826 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
fc7be130 | 2827 | if (IS_MNT_UNBINDABLE(p)) |
9676f0c6 RP |
2828 | return 1; |
2829 | } | |
2830 | return 0; | |
2831 | } | |
2832 | ||
44dfd84a DH |
2833 | /* |
2834 | * Check that there aren't references to earlier/same mount namespaces in the | |
2835 | * specified subtree. Such references can act as pins for mount namespaces | |
2836 | * that aren't checked by the mount-cycle checking code, thereby allowing | |
2837 | * cycles to be made. | |
2838 | */ | |
2839 | static bool check_for_nsfs_mounts(struct mount *subtree) | |
2840 | { | |
2841 | struct mount *p; | |
2842 | bool ret = false; | |
2843 | ||
2844 | lock_mount_hash(); | |
2845 | for (p = subtree; p; p = next_mnt(p, subtree)) | |
2846 | if (mnt_ns_loop(p->mnt.mnt_root)) | |
2847 | goto out; | |
2848 | ||
2849 | ret = true; | |
2850 | out: | |
2851 | unlock_mount_hash(); | |
2852 | return ret; | |
2853 | } | |
2854 | ||
9ffb14ef PT |
2855 | static int do_set_group(struct path *from_path, struct path *to_path) |
2856 | { | |
2857 | struct mount *from, *to; | |
2858 | int err; | |
2859 | ||
2860 | from = real_mount(from_path->mnt); | |
2861 | to = real_mount(to_path->mnt); | |
2862 | ||
2863 | namespace_lock(); | |
2864 | ||
2865 | err = -EINVAL; | |
2866 | /* To and From must be mounted */ | |
2867 | if (!is_mounted(&from->mnt)) | |
2868 | goto out; | |
2869 | if (!is_mounted(&to->mnt)) | |
2870 | goto out; | |
2871 | ||
2872 | err = -EPERM; | |
2873 | /* We should be allowed to modify mount namespaces of both mounts */ | |
2874 | if (!ns_capable(from->mnt_ns->user_ns, CAP_SYS_ADMIN)) | |
2875 | goto out; | |
2876 | if (!ns_capable(to->mnt_ns->user_ns, CAP_SYS_ADMIN)) | |
2877 | goto out; | |
2878 | ||
2879 | err = -EINVAL; | |
2880 | /* To and From paths should be mount roots */ | |
2881 | if (from_path->dentry != from_path->mnt->mnt_root) | |
2882 | goto out; | |
2883 | if (to_path->dentry != to_path->mnt->mnt_root) | |
2884 | goto out; | |
2885 | ||
2886 | /* Setting sharing groups is only allowed across same superblock */ | |
2887 | if (from->mnt.mnt_sb != to->mnt.mnt_sb) | |
2888 | goto out; | |
2889 | ||
2890 | /* From mount root should be wider than To mount root */ | |
2891 | if (!is_subdir(to->mnt.mnt_root, from->mnt.mnt_root)) | |
2892 | goto out; | |
2893 | ||
2894 | /* From mount should not have locked children in place of To's root */ | |
2895 | if (has_locked_children(from, to->mnt.mnt_root)) | |
2896 | goto out; | |
2897 | ||
2898 | /* Setting sharing groups is only allowed on private mounts */ | |
2899 | if (IS_MNT_SHARED(to) || IS_MNT_SLAVE(to)) | |
2900 | goto out; | |
2901 | ||
2902 | /* From should not be private */ | |
2903 | if (!IS_MNT_SHARED(from) && !IS_MNT_SLAVE(from)) | |
2904 | goto out; | |
2905 | ||
2906 | if (IS_MNT_SLAVE(from)) { | |
2907 | struct mount *m = from->mnt_master; | |
2908 | ||
2909 | list_add(&to->mnt_slave, &m->mnt_slave_list); | |
2910 | to->mnt_master = m; | |
2911 | } | |
2912 | ||
2913 | if (IS_MNT_SHARED(from)) { | |
2914 | to->mnt_group_id = from->mnt_group_id; | |
2915 | list_add(&to->mnt_share, &from->mnt_share); | |
2916 | lock_mount_hash(); | |
2917 | set_mnt_shared(to); | |
2918 | unlock_mount_hash(); | |
2919 | } | |
2920 | ||
2921 | err = 0; | |
2922 | out: | |
2923 | namespace_unlock(); | |
2924 | return err; | |
2925 | } | |
2926 | ||
2db154b3 | 2927 | static int do_move_mount(struct path *old_path, struct path *new_path) |
1da177e4 | 2928 | { |
44dfd84a | 2929 | struct mnt_namespace *ns; |
676da58d | 2930 | struct mount *p; |
0fb54e50 | 2931 | struct mount *old; |
2763d119 AV |
2932 | struct mount *parent; |
2933 | struct mountpoint *mp, *old_mp; | |
57eccb83 | 2934 | int err; |
44dfd84a | 2935 | bool attached; |
1da177e4 | 2936 | |
2db154b3 | 2937 | mp = lock_mount(new_path); |
84d17192 | 2938 | if (IS_ERR(mp)) |
2db154b3 | 2939 | return PTR_ERR(mp); |
cc53ce53 | 2940 | |
2db154b3 DH |
2941 | old = real_mount(old_path->mnt); |
2942 | p = real_mount(new_path->mnt); | |
2763d119 | 2943 | parent = old->mnt_parent; |
44dfd84a | 2944 | attached = mnt_has_parent(old); |
2763d119 | 2945 | old_mp = old->mnt_mp; |
44dfd84a | 2946 | ns = old->mnt_ns; |
143c8c91 | 2947 | |
1da177e4 | 2948 | err = -EINVAL; |
44dfd84a DH |
2949 | /* The mountpoint must be in our namespace. */ |
2950 | if (!check_mnt(p)) | |
2db154b3 | 2951 | goto out; |
1da177e4 | 2952 | |
570d7a98 EB |
2953 | /* The thing moved must be mounted... */ |
2954 | if (!is_mounted(&old->mnt)) | |
44dfd84a DH |
2955 | goto out; |
2956 | ||
570d7a98 EB |
2957 | /* ... and either ours or the root of anon namespace */ |
2958 | if (!(attached ? check_mnt(old) : is_anon_ns(ns))) | |
2db154b3 | 2959 | goto out; |
5ff9d8a6 | 2960 | |
2db154b3 DH |
2961 | if (old->mnt.mnt_flags & MNT_LOCKED) |
2962 | goto out; | |
1da177e4 | 2963 | |
2db154b3 DH |
2964 | if (old_path->dentry != old_path->mnt->mnt_root) |
2965 | goto out; | |
1da177e4 | 2966 | |
2db154b3 DH |
2967 | if (d_is_dir(new_path->dentry) != |
2968 | d_is_dir(old_path->dentry)) | |
2969 | goto out; | |
21444403 RP |
2970 | /* |
2971 | * Don't move a mount residing in a shared parent. | |
2972 | */ | |
2763d119 | 2973 | if (attached && IS_MNT_SHARED(parent)) |
2db154b3 | 2974 | goto out; |
9676f0c6 RP |
2975 | /* |
2976 | * Don't move a mount tree containing unbindable mounts to a destination | |
2977 | * mount which is shared. | |
2978 | */ | |
fc7be130 | 2979 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
2db154b3 | 2980 | goto out; |
1da177e4 | 2981 | err = -ELOOP; |
44dfd84a DH |
2982 | if (!check_for_nsfs_mounts(old)) |
2983 | goto out; | |
fc7be130 | 2984 | for (; mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 2985 | if (p == old) |
2db154b3 | 2986 | goto out; |
1da177e4 | 2987 | |
2db154b3 | 2988 | err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, |
2763d119 | 2989 | attached); |
4ac91378 | 2990 | if (err) |
2db154b3 | 2991 | goto out; |
1da177e4 LT |
2992 | |
2993 | /* if the mount is moved, it should no longer be expire | |
2994 | * automatically */ | |
6776db3d | 2995 | list_del_init(&old->mnt_expire); |
2763d119 AV |
2996 | if (attached) |
2997 | put_mountpoint(old_mp); | |
1da177e4 | 2998 | out: |
2db154b3 | 2999 | unlock_mount(mp); |
44dfd84a | 3000 | if (!err) { |
2763d119 AV |
3001 | if (attached) |
3002 | mntput_no_expire(parent); | |
3003 | else | |
44dfd84a DH |
3004 | free_mnt_ns(ns); |
3005 | } | |
2db154b3 DH |
3006 | return err; |
3007 | } | |
3008 | ||
3009 | static int do_move_mount_old(struct path *path, const char *old_name) | |
3010 | { | |
3011 | struct path old_path; | |
3012 | int err; | |
3013 | ||
3014 | if (!old_name || !*old_name) | |
3015 | return -EINVAL; | |
3016 | ||
3017 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); | |
3018 | if (err) | |
3019 | return err; | |
3020 | ||
3021 | err = do_move_mount(&old_path, path); | |
2d92ab3c | 3022 | path_put(&old_path); |
1da177e4 LT |
3023 | return err; |
3024 | } | |
3025 | ||
9d412a43 AV |
3026 | /* |
3027 | * add a mount into a namespace's mount tree | |
3028 | */ | |
8f11538e | 3029 | static int do_add_mount(struct mount *newmnt, struct mountpoint *mp, |
1e2d8464 | 3030 | const struct path *path, int mnt_flags) |
9d412a43 | 3031 | { |
8f11538e | 3032 | struct mount *parent = real_mount(path->mnt); |
9d412a43 | 3033 | |
f2ebb3a9 | 3034 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
9d412a43 | 3035 | |
84d17192 | 3036 | if (unlikely(!check_mnt(parent))) { |
156cacb1 AV |
3037 | /* that's acceptable only for automounts done in private ns */ |
3038 | if (!(mnt_flags & MNT_SHRINKABLE)) | |
8f11538e | 3039 | return -EINVAL; |
156cacb1 | 3040 | /* ... and for those we'd better have mountpoint still alive */ |
84d17192 | 3041 | if (!parent->mnt_ns) |
8f11538e | 3042 | return -EINVAL; |
156cacb1 | 3043 | } |
9d412a43 AV |
3044 | |
3045 | /* Refuse the same filesystem on the same mount point */ | |
95bc5f25 | 3046 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 | 3047 | path->mnt->mnt_root == path->dentry) |
8f11538e | 3048 | return -EBUSY; |
9d412a43 | 3049 | |
e36cb0b8 | 3050 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
8f11538e | 3051 | return -EINVAL; |
9d412a43 | 3052 | |
95bc5f25 | 3053 | newmnt->mnt.mnt_flags = mnt_flags; |
8f11538e | 3054 | return graft_tree(newmnt, parent, mp); |
9d412a43 | 3055 | } |
b1e75df4 | 3056 | |
132e4608 DH |
3057 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags); |
3058 | ||
3059 | /* | |
3060 | * Create a new mount using a superblock configuration and request it | |
3061 | * be added to the namespace tree. | |
3062 | */ | |
3063 | static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, | |
3064 | unsigned int mnt_flags) | |
3065 | { | |
3066 | struct vfsmount *mnt; | |
8f11538e | 3067 | struct mountpoint *mp; |
132e4608 DH |
3068 | struct super_block *sb = fc->root->d_sb; |
3069 | int error; | |
3070 | ||
c9ce29ed AV |
3071 | error = security_sb_kern_mount(sb); |
3072 | if (!error && mount_too_revealing(sb, &mnt_flags)) | |
3073 | error = -EPERM; | |
3074 | ||
3075 | if (unlikely(error)) { | |
3076 | fc_drop_locked(fc); | |
3077 | return error; | |
132e4608 DH |
3078 | } |
3079 | ||
3080 | up_write(&sb->s_umount); | |
3081 | ||
3082 | mnt = vfs_create_mount(fc); | |
3083 | if (IS_ERR(mnt)) | |
3084 | return PTR_ERR(mnt); | |
3085 | ||
f8b92ba6 DD |
3086 | mnt_warn_timestamp_expiry(mountpoint, mnt); |
3087 | ||
8f11538e AV |
3088 | mp = lock_mount(mountpoint); |
3089 | if (IS_ERR(mp)) { | |
3090 | mntput(mnt); | |
3091 | return PTR_ERR(mp); | |
3092 | } | |
3093 | error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags); | |
3094 | unlock_mount(mp); | |
0ecee669 EB |
3095 | if (error < 0) |
3096 | mntput(mnt); | |
132e4608 DH |
3097 | return error; |
3098 | } | |
1b852bce | 3099 | |
1da177e4 LT |
3100 | /* |
3101 | * create a new mount for userspace and request it to be added into the | |
3102 | * namespace's tree | |
3103 | */ | |
e462ec50 | 3104 | static int do_new_mount(struct path *path, const char *fstype, int sb_flags, |
808d4e3c | 3105 | int mnt_flags, const char *name, void *data) |
1da177e4 | 3106 | { |
0c55cfc4 | 3107 | struct file_system_type *type; |
a0c9a8b8 AV |
3108 | struct fs_context *fc; |
3109 | const char *subtype = NULL; | |
3110 | int err = 0; | |
1da177e4 | 3111 | |
0c55cfc4 | 3112 | if (!fstype) |
1da177e4 LT |
3113 | return -EINVAL; |
3114 | ||
0c55cfc4 EB |
3115 | type = get_fs_type(fstype); |
3116 | if (!type) | |
3117 | return -ENODEV; | |
3118 | ||
a0c9a8b8 AV |
3119 | if (type->fs_flags & FS_HAS_SUBTYPE) { |
3120 | subtype = strchr(fstype, '.'); | |
3121 | if (subtype) { | |
3122 | subtype++; | |
3123 | if (!*subtype) { | |
3124 | put_filesystem(type); | |
3125 | return -EINVAL; | |
3126 | } | |
a0c9a8b8 AV |
3127 | } |
3128 | } | |
0c55cfc4 | 3129 | |
a0c9a8b8 | 3130 | fc = fs_context_for_mount(type, sb_flags); |
0c55cfc4 | 3131 | put_filesystem(type); |
a0c9a8b8 AV |
3132 | if (IS_ERR(fc)) |
3133 | return PTR_ERR(fc); | |
3134 | ||
3e1aeb00 DH |
3135 | if (subtype) |
3136 | err = vfs_parse_fs_string(fc, "subtype", | |
3137 | subtype, strlen(subtype)); | |
3138 | if (!err && name) | |
3139 | err = vfs_parse_fs_string(fc, "source", name, strlen(name)); | |
a0c9a8b8 AV |
3140 | if (!err) |
3141 | err = parse_monolithic_mount_data(fc, data); | |
c3aabf07 AV |
3142 | if (!err && !mount_capable(fc)) |
3143 | err = -EPERM; | |
a0c9a8b8 AV |
3144 | if (!err) |
3145 | err = vfs_get_tree(fc); | |
132e4608 DH |
3146 | if (!err) |
3147 | err = do_new_mount_fc(fc, path, mnt_flags); | |
8654df4e | 3148 | |
a0c9a8b8 | 3149 | put_fs_context(fc); |
15f9a3f3 | 3150 | return err; |
1da177e4 LT |
3151 | } |
3152 | ||
1e2d8464 | 3153 | int finish_automount(struct vfsmount *m, const struct path *path) |
19a167af | 3154 | { |
26df6034 | 3155 | struct dentry *dentry = path->dentry; |
8f11538e | 3156 | struct mountpoint *mp; |
25e195aa | 3157 | struct mount *mnt; |
19a167af | 3158 | int err; |
25e195aa AV |
3159 | |
3160 | if (!m) | |
3161 | return 0; | |
3162 | if (IS_ERR(m)) | |
3163 | return PTR_ERR(m); | |
3164 | ||
3165 | mnt = real_mount(m); | |
19a167af AV |
3166 | /* The new mount record should have at least 2 refs to prevent it being |
3167 | * expired before we get a chance to add it | |
3168 | */ | |
6776db3d | 3169 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
3170 | |
3171 | if (m->mnt_sb == path->mnt->mnt_sb && | |
26df6034 | 3172 | m->mnt_root == dentry) { |
b1e75df4 | 3173 | err = -ELOOP; |
26df6034 | 3174 | goto discard; |
19a167af AV |
3175 | } |
3176 | ||
26df6034 AV |
3177 | /* |
3178 | * we don't want to use lock_mount() - in this case finding something | |
3179 | * that overmounts our mountpoint to be means "quitely drop what we've | |
3180 | * got", not "try to mount it on top". | |
3181 | */ | |
3182 | inode_lock(dentry->d_inode); | |
3183 | namespace_lock(); | |
3184 | if (unlikely(cant_mount(dentry))) { | |
3185 | err = -ENOENT; | |
3186 | goto discard_locked; | |
3187 | } | |
3188 | rcu_read_lock(); | |
3189 | if (unlikely(__lookup_mnt(path->mnt, dentry))) { | |
3190 | rcu_read_unlock(); | |
3191 | err = 0; | |
3192 | goto discard_locked; | |
3193 | } | |
3194 | rcu_read_unlock(); | |
3195 | mp = get_mountpoint(dentry); | |
8f11538e AV |
3196 | if (IS_ERR(mp)) { |
3197 | err = PTR_ERR(mp); | |
26df6034 | 3198 | goto discard_locked; |
8f11538e | 3199 | } |
26df6034 | 3200 | |
8f11538e AV |
3201 | err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
3202 | unlock_mount(mp); | |
26df6034 AV |
3203 | if (unlikely(err)) |
3204 | goto discard; | |
3205 | mntput(m); | |
3206 | return 0; | |
3207 | ||
3208 | discard_locked: | |
3209 | namespace_unlock(); | |
3210 | inode_unlock(dentry->d_inode); | |
3211 | discard: | |
b1e75df4 | 3212 | /* remove m from any expiration list it may be on */ |
6776db3d | 3213 | if (!list_empty(&mnt->mnt_expire)) { |
97216be0 | 3214 | namespace_lock(); |
6776db3d | 3215 | list_del_init(&mnt->mnt_expire); |
97216be0 | 3216 | namespace_unlock(); |
19a167af | 3217 | } |
b1e75df4 AV |
3218 | mntput(m); |
3219 | mntput(m); | |
19a167af AV |
3220 | return err; |
3221 | } | |
3222 | ||
ea5b778a DH |
3223 | /** |
3224 | * mnt_set_expiry - Put a mount on an expiration list | |
3225 | * @mnt: The mount to list. | |
3226 | * @expiry_list: The list to add the mount to. | |
3227 | */ | |
3228 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
3229 | { | |
97216be0 | 3230 | namespace_lock(); |
ea5b778a | 3231 | |
6776db3d | 3232 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a | 3233 | |
97216be0 | 3234 | namespace_unlock(); |
ea5b778a DH |
3235 | } |
3236 | EXPORT_SYMBOL(mnt_set_expiry); | |
3237 | ||
1da177e4 LT |
3238 | /* |
3239 | * process a list of expirable mountpoints with the intent of discarding any | |
3240 | * mountpoints that aren't in use and haven't been touched since last we came | |
3241 | * here | |
3242 | */ | |
3243 | void mark_mounts_for_expiry(struct list_head *mounts) | |
3244 | { | |
761d5c38 | 3245 | struct mount *mnt, *next; |
1da177e4 LT |
3246 | LIST_HEAD(graveyard); |
3247 | ||
3248 | if (list_empty(mounts)) | |
3249 | return; | |
3250 | ||
97216be0 | 3251 | namespace_lock(); |
719ea2fb | 3252 | lock_mount_hash(); |
1da177e4 LT |
3253 | |
3254 | /* extract from the expiration list every vfsmount that matches the | |
3255 | * following criteria: | |
3256 | * - only referenced by its parent vfsmount | |
3257 | * - still marked for expiry (marked on the last call here; marks are | |
3258 | * cleared by mntput()) | |
3259 | */ | |
6776db3d | 3260 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
863d684f | 3261 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1ab59738 | 3262 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 3263 | continue; |
6776db3d | 3264 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 3265 | } |
bcc5c7d2 | 3266 | while (!list_empty(&graveyard)) { |
6776db3d | 3267 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
143c8c91 | 3268 | touch_mnt_namespace(mnt->mnt_ns); |
e819f152 | 3269 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 | 3270 | } |
719ea2fb | 3271 | unlock_mount_hash(); |
3ab6abee | 3272 | namespace_unlock(); |
5528f911 TM |
3273 | } |
3274 | ||
3275 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
3276 | ||
3277 | /* | |
3278 | * Ripoff of 'select_parent()' | |
3279 | * | |
3280 | * search the list of submounts for a given mountpoint, and move any | |
3281 | * shrinkable submounts to the 'graveyard' list. | |
3282 | */ | |
692afc31 | 3283 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 3284 | { |
692afc31 | 3285 | struct mount *this_parent = parent; |
5528f911 TM |
3286 | struct list_head *next; |
3287 | int found = 0; | |
3288 | ||
3289 | repeat: | |
6b41d536 | 3290 | next = this_parent->mnt_mounts.next; |
5528f911 | 3291 | resume: |
6b41d536 | 3292 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 3293 | struct list_head *tmp = next; |
6b41d536 | 3294 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
3295 | |
3296 | next = tmp->next; | |
692afc31 | 3297 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 3298 | continue; |
5528f911 TM |
3299 | /* |
3300 | * Descend a level if the d_mounts list is non-empty. | |
3301 | */ | |
6b41d536 | 3302 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
3303 | this_parent = mnt; |
3304 | goto repeat; | |
3305 | } | |
1da177e4 | 3306 | |
1ab59738 | 3307 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 3308 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
3309 | found++; |
3310 | } | |
1da177e4 | 3311 | } |
5528f911 TM |
3312 | /* |
3313 | * All done at this level ... ascend and resume the search | |
3314 | */ | |
3315 | if (this_parent != parent) { | |
6b41d536 | 3316 | next = this_parent->mnt_child.next; |
0714a533 | 3317 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
3318 | goto resume; |
3319 | } | |
3320 | return found; | |
3321 | } | |
3322 | ||
3323 | /* | |
3324 | * process a list of expirable mountpoints with the intent of discarding any | |
3325 | * submounts of a specific parent mountpoint | |
99b7db7b | 3326 | * |
48a066e7 | 3327 | * mount_lock must be held for write |
5528f911 | 3328 | */ |
b54b9be7 | 3329 | static void shrink_submounts(struct mount *mnt) |
5528f911 TM |
3330 | { |
3331 | LIST_HEAD(graveyard); | |
761d5c38 | 3332 | struct mount *m; |
5528f911 | 3333 | |
5528f911 | 3334 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 3335 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 3336 | while (!list_empty(&graveyard)) { |
761d5c38 | 3337 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 3338 | mnt_expire); |
143c8c91 | 3339 | touch_mnt_namespace(m->mnt_ns); |
e819f152 | 3340 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 AV |
3341 | } |
3342 | } | |
1da177e4 LT |
3343 | } |
3344 | ||
028abd92 | 3345 | static void *copy_mount_options(const void __user * data) |
1da177e4 | 3346 | { |
b40ef869 | 3347 | char *copy; |
d563d678 | 3348 | unsigned left, offset; |
b58fed8b | 3349 | |
1da177e4 | 3350 | if (!data) |
b40ef869 | 3351 | return NULL; |
1da177e4 | 3352 | |
b40ef869 AV |
3353 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
3354 | if (!copy) | |
3355 | return ERR_PTR(-ENOMEM); | |
1da177e4 | 3356 | |
d563d678 | 3357 | left = copy_from_user(copy, data, PAGE_SIZE); |
1da177e4 | 3358 | |
d563d678 CM |
3359 | /* |
3360 | * Not all architectures have an exact copy_from_user(). Resort to | |
3361 | * byte at a time. | |
3362 | */ | |
3363 | offset = PAGE_SIZE - left; | |
3364 | while (left) { | |
3365 | char c; | |
3366 | if (get_user(c, (const char __user *)data + offset)) | |
3367 | break; | |
3368 | copy[offset] = c; | |
3369 | left--; | |
3370 | offset++; | |
3371 | } | |
3372 | ||
3373 | if (left == PAGE_SIZE) { | |
b40ef869 AV |
3374 | kfree(copy); |
3375 | return ERR_PTR(-EFAULT); | |
1da177e4 | 3376 | } |
d563d678 | 3377 | |
b40ef869 | 3378 | return copy; |
1da177e4 LT |
3379 | } |
3380 | ||
028abd92 | 3381 | static char *copy_mount_string(const void __user *data) |
eca6f534 | 3382 | { |
fbdb4401 | 3383 | return data ? strndup_user(data, PATH_MAX) : NULL; |
eca6f534 VN |
3384 | } |
3385 | ||
1da177e4 LT |
3386 | /* |
3387 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
3388 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
3389 | * | |
3390 | * data is a (void *) that can point to any structure up to | |
3391 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
3392 | * information (or be NULL). | |
3393 | * | |
3394 | * Pre-0.97 versions of mount() didn't have a flags word. | |
3395 | * When the flags word was introduced its top half was required | |
3396 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
3397 | * Therefore, if this magic number is present, it carries no information | |
3398 | * and must be discarded. | |
3399 | */ | |
c60166f0 | 3400 | int path_mount(const char *dev_name, struct path *path, |
808d4e3c | 3401 | const char *type_page, unsigned long flags, void *data_page) |
1da177e4 | 3402 | { |
e462ec50 | 3403 | unsigned int mnt_flags = 0, sb_flags; |
a1e6aaa3 | 3404 | int ret; |
1da177e4 LT |
3405 | |
3406 | /* Discard magic */ | |
3407 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
3408 | flags &= ~MS_MGC_MSK; | |
3409 | ||
3410 | /* Basic sanity checks */ | |
1da177e4 LT |
3411 | if (data_page) |
3412 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
3413 | ||
e462ec50 DH |
3414 | if (flags & MS_NOUSER) |
3415 | return -EINVAL; | |
3416 | ||
a1e6aaa3 CH |
3417 | ret = security_sb_mount(dev_name, path, type_page, flags, data_page); |
3418 | if (ret) | |
3419 | return ret; | |
3420 | if (!may_mount()) | |
3421 | return -EPERM; | |
f7e33bdb JL |
3422 | if (flags & SB_MANDLOCK) |
3423 | warn_mandlock(); | |
a27ab9f2 | 3424 | |
613cbe3d AK |
3425 | /* Default to relatime unless overriden */ |
3426 | if (!(flags & MS_NOATIME)) | |
3427 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 3428 | |
1da177e4 LT |
3429 | /* Separate the per-mountpoint flags */ |
3430 | if (flags & MS_NOSUID) | |
3431 | mnt_flags |= MNT_NOSUID; | |
3432 | if (flags & MS_NODEV) | |
3433 | mnt_flags |= MNT_NODEV; | |
3434 | if (flags & MS_NOEXEC) | |
3435 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
3436 | if (flags & MS_NOATIME) |
3437 | mnt_flags |= MNT_NOATIME; | |
3438 | if (flags & MS_NODIRATIME) | |
3439 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
3440 | if (flags & MS_STRICTATIME) |
3441 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
a9e5b732 | 3442 | if (flags & MS_RDONLY) |
2e4b7fcd | 3443 | mnt_flags |= MNT_READONLY; |
dab741e0 MN |
3444 | if (flags & MS_NOSYMFOLLOW) |
3445 | mnt_flags |= MNT_NOSYMFOLLOW; | |
fc33a7bb | 3446 | |
ffbc6f0e EB |
3447 | /* The default atime for remount is preservation */ |
3448 | if ((flags & MS_REMOUNT) && | |
3449 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | | |
3450 | MS_STRICTATIME)) == 0)) { | |
3451 | mnt_flags &= ~MNT_ATIME_MASK; | |
a1e6aaa3 | 3452 | mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; |
ffbc6f0e EB |
3453 | } |
3454 | ||
e462ec50 DH |
3455 | sb_flags = flags & (SB_RDONLY | |
3456 | SB_SYNCHRONOUS | | |
3457 | SB_MANDLOCK | | |
3458 | SB_DIRSYNC | | |
3459 | SB_SILENT | | |
917086ff | 3460 | SB_POSIXACL | |
d7ee9469 | 3461 | SB_LAZYTIME | |
917086ff | 3462 | SB_I_VERSION); |
1da177e4 | 3463 | |
43f5e655 | 3464 | if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) |
a1e6aaa3 CH |
3465 | return do_reconfigure_mnt(path, mnt_flags); |
3466 | if (flags & MS_REMOUNT) | |
3467 | return do_remount(path, flags, sb_flags, mnt_flags, data_page); | |
3468 | if (flags & MS_BIND) | |
3469 | return do_loopback(path, dev_name, flags & MS_REC); | |
3470 | if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
3471 | return do_change_type(path, flags); | |
3472 | if (flags & MS_MOVE) | |
3473 | return do_move_mount_old(path, dev_name); | |
3474 | ||
3475 | return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, | |
3476 | data_page); | |
3477 | } | |
3478 | ||
3479 | long do_mount(const char *dev_name, const char __user *dir_name, | |
3480 | const char *type_page, unsigned long flags, void *data_page) | |
3481 | { | |
3482 | struct path path; | |
3483 | int ret; | |
3484 | ||
3485 | ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); | |
3486 | if (ret) | |
3487 | return ret; | |
3488 | ret = path_mount(dev_name, &path, type_page, flags, data_page); | |
2d92ab3c | 3489 | path_put(&path); |
a1e6aaa3 | 3490 | return ret; |
1da177e4 LT |
3491 | } |
3492 | ||
537f7ccb EB |
3493 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
3494 | { | |
3495 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); | |
3496 | } | |
3497 | ||
3498 | static void dec_mnt_namespaces(struct ucounts *ucounts) | |
3499 | { | |
3500 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); | |
3501 | } | |
3502 | ||
771b1371 EB |
3503 | static void free_mnt_ns(struct mnt_namespace *ns) |
3504 | { | |
74e83122 AV |
3505 | if (!is_anon_ns(ns)) |
3506 | ns_free_inum(&ns->ns); | |
537f7ccb | 3507 | dec_mnt_namespaces(ns->ucounts); |
771b1371 EB |
3508 | put_user_ns(ns->user_ns); |
3509 | kfree(ns); | |
3510 | } | |
3511 | ||
8823c079 EB |
3512 | /* |
3513 | * Assign a sequence number so we can detect when we attempt to bind | |
3514 | * mount a reference to an older mount namespace into the current | |
3515 | * mount namespace, preventing reference counting loops. A 64bit | |
3516 | * number incrementing at 10Ghz will take 12,427 years to wrap which | |
3517 | * is effectively never, so we can ignore the possibility. | |
3518 | */ | |
3519 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); | |
3520 | ||
74e83122 | 3521 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon) |
cf8d2c11 TM |
3522 | { |
3523 | struct mnt_namespace *new_ns; | |
537f7ccb | 3524 | struct ucounts *ucounts; |
98f842e6 | 3525 | int ret; |
cf8d2c11 | 3526 | |
537f7ccb EB |
3527 | ucounts = inc_mnt_namespaces(user_ns); |
3528 | if (!ucounts) | |
df75e774 | 3529 | return ERR_PTR(-ENOSPC); |
537f7ccb | 3530 | |
30acd0bd | 3531 | new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL_ACCOUNT); |
537f7ccb EB |
3532 | if (!new_ns) { |
3533 | dec_mnt_namespaces(ucounts); | |
cf8d2c11 | 3534 | return ERR_PTR(-ENOMEM); |
537f7ccb | 3535 | } |
74e83122 AV |
3536 | if (!anon) { |
3537 | ret = ns_alloc_inum(&new_ns->ns); | |
3538 | if (ret) { | |
3539 | kfree(new_ns); | |
3540 | dec_mnt_namespaces(ucounts); | |
3541 | return ERR_PTR(ret); | |
3542 | } | |
98f842e6 | 3543 | } |
33c42940 | 3544 | new_ns->ns.ops = &mntns_operations; |
74e83122 AV |
3545 | if (!anon) |
3546 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); | |
1a7b8969 | 3547 | refcount_set(&new_ns->ns.count, 1); |
cf8d2c11 TM |
3548 | INIT_LIST_HEAD(&new_ns->list); |
3549 | init_waitqueue_head(&new_ns->poll); | |
9f6c61f9 | 3550 | spin_lock_init(&new_ns->ns_lock); |
771b1371 | 3551 | new_ns->user_ns = get_user_ns(user_ns); |
537f7ccb | 3552 | new_ns->ucounts = ucounts; |
cf8d2c11 TM |
3553 | return new_ns; |
3554 | } | |
3555 | ||
0766f788 | 3556 | __latent_entropy |
9559f689 AV |
3557 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
3558 | struct user_namespace *user_ns, struct fs_struct *new_fs) | |
1da177e4 | 3559 | { |
6b3286ed | 3560 | struct mnt_namespace *new_ns; |
7f2da1e7 | 3561 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 3562 | struct mount *p, *q; |
9559f689 | 3563 | struct mount *old; |
cb338d06 | 3564 | struct mount *new; |
7a472ef4 | 3565 | int copy_flags; |
1da177e4 | 3566 | |
9559f689 AV |
3567 | BUG_ON(!ns); |
3568 | ||
3569 | if (likely(!(flags & CLONE_NEWNS))) { | |
3570 | get_mnt_ns(ns); | |
3571 | return ns; | |
3572 | } | |
3573 | ||
3574 | old = ns->root; | |
3575 | ||
74e83122 | 3576 | new_ns = alloc_mnt_ns(user_ns, false); |
cf8d2c11 TM |
3577 | if (IS_ERR(new_ns)) |
3578 | return new_ns; | |
1da177e4 | 3579 | |
97216be0 | 3580 | namespace_lock(); |
1da177e4 | 3581 | /* First pass: copy the tree topology */ |
4ce5d2b1 | 3582 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
9559f689 | 3583 | if (user_ns != ns->user_ns) |
3bd045cc | 3584 | copy_flags |= CL_SHARED_TO_SLAVE; |
7a472ef4 | 3585 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
be34d1a3 | 3586 | if (IS_ERR(new)) { |
328e6d90 | 3587 | namespace_unlock(); |
771b1371 | 3588 | free_mnt_ns(new_ns); |
be34d1a3 | 3589 | return ERR_CAST(new); |
1da177e4 | 3590 | } |
3bd045cc AV |
3591 | if (user_ns != ns->user_ns) { |
3592 | lock_mount_hash(); | |
3593 | lock_mnt_tree(new); | |
3594 | unlock_mount_hash(); | |
3595 | } | |
be08d6d2 | 3596 | new_ns->root = new; |
1a4eeaf2 | 3597 | list_add_tail(&new_ns->list, &new->mnt_list); |
1da177e4 LT |
3598 | |
3599 | /* | |
3600 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
3601 | * as belonging to new namespace. We have already acquired a private | |
3602 | * fs_struct, so tsk->fs->lock is not needed. | |
3603 | */ | |
909b0a88 | 3604 | p = old; |
cb338d06 | 3605 | q = new; |
1da177e4 | 3606 | while (p) { |
143c8c91 | 3607 | q->mnt_ns = new_ns; |
d2921684 | 3608 | new_ns->mounts++; |
9559f689 AV |
3609 | if (new_fs) { |
3610 | if (&p->mnt == new_fs->root.mnt) { | |
3611 | new_fs->root.mnt = mntget(&q->mnt); | |
315fc83e | 3612 | rootmnt = &p->mnt; |
1da177e4 | 3613 | } |
9559f689 AV |
3614 | if (&p->mnt == new_fs->pwd.mnt) { |
3615 | new_fs->pwd.mnt = mntget(&q->mnt); | |
315fc83e | 3616 | pwdmnt = &p->mnt; |
1da177e4 | 3617 | } |
1da177e4 | 3618 | } |
909b0a88 AV |
3619 | p = next_mnt(p, old); |
3620 | q = next_mnt(q, new); | |
4ce5d2b1 EB |
3621 | if (!q) |
3622 | break; | |
61d8e426 | 3623 | // an mntns binding we'd skipped? |
4ce5d2b1 | 3624 | while (p->mnt.mnt_root != q->mnt.mnt_root) |
61d8e426 | 3625 | p = next_mnt(skip_mnt_tree(p), old); |
1da177e4 | 3626 | } |
328e6d90 | 3627 | namespace_unlock(); |
1da177e4 | 3628 | |
1da177e4 | 3629 | if (rootmnt) |
f03c6599 | 3630 | mntput(rootmnt); |
1da177e4 | 3631 | if (pwdmnt) |
f03c6599 | 3632 | mntput(pwdmnt); |
1da177e4 | 3633 | |
741a2951 | 3634 | return new_ns; |
1da177e4 LT |
3635 | } |
3636 | ||
74e83122 | 3637 | struct dentry *mount_subtree(struct vfsmount *m, const char *name) |
ea441d11 | 3638 | { |
74e83122 | 3639 | struct mount *mnt = real_mount(m); |
ea441d11 | 3640 | struct mnt_namespace *ns; |
d31da0f0 | 3641 | struct super_block *s; |
ea441d11 AV |
3642 | struct path path; |
3643 | int err; | |
3644 | ||
74e83122 AV |
3645 | ns = alloc_mnt_ns(&init_user_ns, true); |
3646 | if (IS_ERR(ns)) { | |
3647 | mntput(m); | |
ea441d11 | 3648 | return ERR_CAST(ns); |
74e83122 AV |
3649 | } |
3650 | mnt->mnt_ns = ns; | |
3651 | ns->root = mnt; | |
3652 | ns->mounts++; | |
3653 | list_add(&mnt->mnt_list, &ns->list); | |
ea441d11 | 3654 | |
74e83122 | 3655 | err = vfs_path_lookup(m->mnt_root, m, |
ea441d11 AV |
3656 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
3657 | ||
3658 | put_mnt_ns(ns); | |
3659 | ||
3660 | if (err) | |
3661 | return ERR_PTR(err); | |
3662 | ||
3663 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
3664 | s = path.mnt->mnt_sb; |
3665 | atomic_inc(&s->s_active); | |
ea441d11 AV |
3666 | mntput(path.mnt); |
3667 | /* lock the sucker */ | |
d31da0f0 | 3668 | down_write(&s->s_umount); |
ea441d11 AV |
3669 | /* ... and return the root of (sub)tree on it */ |
3670 | return path.dentry; | |
3671 | } | |
3672 | EXPORT_SYMBOL(mount_subtree); | |
3673 | ||
cccaa5e3 DB |
3674 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
3675 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 3676 | { |
eca6f534 VN |
3677 | int ret; |
3678 | char *kernel_type; | |
eca6f534 | 3679 | char *kernel_dev; |
b40ef869 | 3680 | void *options; |
1da177e4 | 3681 | |
b8850d1f TG |
3682 | kernel_type = copy_mount_string(type); |
3683 | ret = PTR_ERR(kernel_type); | |
3684 | if (IS_ERR(kernel_type)) | |
eca6f534 | 3685 | goto out_type; |
1da177e4 | 3686 | |
b8850d1f TG |
3687 | kernel_dev = copy_mount_string(dev_name); |
3688 | ret = PTR_ERR(kernel_dev); | |
3689 | if (IS_ERR(kernel_dev)) | |
eca6f534 | 3690 | goto out_dev; |
1da177e4 | 3691 | |
b40ef869 AV |
3692 | options = copy_mount_options(data); |
3693 | ret = PTR_ERR(options); | |
3694 | if (IS_ERR(options)) | |
eca6f534 | 3695 | goto out_data; |
1da177e4 | 3696 | |
b40ef869 | 3697 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
1da177e4 | 3698 | |
b40ef869 | 3699 | kfree(options); |
eca6f534 VN |
3700 | out_data: |
3701 | kfree(kernel_dev); | |
3702 | out_dev: | |
eca6f534 VN |
3703 | kfree(kernel_type); |
3704 | out_type: | |
3705 | return ret; | |
1da177e4 LT |
3706 | } |
3707 | ||
dd8b477f CB |
3708 | #define FSMOUNT_VALID_FLAGS \ |
3709 | (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \ | |
3710 | MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME | \ | |
3711 | MOUNT_ATTR_NOSYMFOLLOW) | |
5b490500 | 3712 | |
9caccd41 | 3713 | #define MOUNT_SETATTR_VALID_FLAGS (FSMOUNT_VALID_FLAGS | MOUNT_ATTR_IDMAP) |
2a186721 CB |
3714 | |
3715 | #define MOUNT_SETATTR_PROPAGATION_FLAGS \ | |
3716 | (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED) | |
3717 | ||
5b490500 CB |
3718 | static unsigned int attr_flags_to_mnt_flags(u64 attr_flags) |
3719 | { | |
3720 | unsigned int mnt_flags = 0; | |
3721 | ||
3722 | if (attr_flags & MOUNT_ATTR_RDONLY) | |
3723 | mnt_flags |= MNT_READONLY; | |
3724 | if (attr_flags & MOUNT_ATTR_NOSUID) | |
3725 | mnt_flags |= MNT_NOSUID; | |
3726 | if (attr_flags & MOUNT_ATTR_NODEV) | |
3727 | mnt_flags |= MNT_NODEV; | |
3728 | if (attr_flags & MOUNT_ATTR_NOEXEC) | |
3729 | mnt_flags |= MNT_NOEXEC; | |
3730 | if (attr_flags & MOUNT_ATTR_NODIRATIME) | |
3731 | mnt_flags |= MNT_NODIRATIME; | |
dd8b477f CB |
3732 | if (attr_flags & MOUNT_ATTR_NOSYMFOLLOW) |
3733 | mnt_flags |= MNT_NOSYMFOLLOW; | |
5b490500 CB |
3734 | |
3735 | return mnt_flags; | |
3736 | } | |
3737 | ||
2db154b3 | 3738 | /* |
93766fbd DH |
3739 | * Create a kernel mount representation for a new, prepared superblock |
3740 | * (specified by fs_fd) and attach to an open_tree-like file descriptor. | |
3741 | */ | |
3742 | SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, | |
3743 | unsigned int, attr_flags) | |
3744 | { | |
3745 | struct mnt_namespace *ns; | |
3746 | struct fs_context *fc; | |
3747 | struct file *file; | |
3748 | struct path newmount; | |
3749 | struct mount *mnt; | |
3750 | struct fd f; | |
3751 | unsigned int mnt_flags = 0; | |
3752 | long ret; | |
3753 | ||
3754 | if (!may_mount()) | |
3755 | return -EPERM; | |
3756 | ||
3757 | if ((flags & ~(FSMOUNT_CLOEXEC)) != 0) | |
3758 | return -EINVAL; | |
3759 | ||
5b490500 | 3760 | if (attr_flags & ~FSMOUNT_VALID_FLAGS) |
93766fbd DH |
3761 | return -EINVAL; |
3762 | ||
5b490500 | 3763 | mnt_flags = attr_flags_to_mnt_flags(attr_flags); |
93766fbd DH |
3764 | |
3765 | switch (attr_flags & MOUNT_ATTR__ATIME) { | |
3766 | case MOUNT_ATTR_STRICTATIME: | |
3767 | break; | |
3768 | case MOUNT_ATTR_NOATIME: | |
3769 | mnt_flags |= MNT_NOATIME; | |
3770 | break; | |
3771 | case MOUNT_ATTR_RELATIME: | |
3772 | mnt_flags |= MNT_RELATIME; | |
3773 | break; | |
3774 | default: | |
3775 | return -EINVAL; | |
3776 | } | |
3777 | ||
3778 | f = fdget(fs_fd); | |
3779 | if (!f.file) | |
3780 | return -EBADF; | |
3781 | ||
3782 | ret = -EINVAL; | |
3783 | if (f.file->f_op != &fscontext_fops) | |
3784 | goto err_fsfd; | |
3785 | ||
3786 | fc = f.file->private_data; | |
3787 | ||
3788 | ret = mutex_lock_interruptible(&fc->uapi_mutex); | |
3789 | if (ret < 0) | |
3790 | goto err_fsfd; | |
3791 | ||
3792 | /* There must be a valid superblock or we can't mount it */ | |
3793 | ret = -EINVAL; | |
3794 | if (!fc->root) | |
3795 | goto err_unlock; | |
3796 | ||
3797 | ret = -EPERM; | |
3798 | if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { | |
3799 | pr_warn("VFS: Mount too revealing\n"); | |
3800 | goto err_unlock; | |
3801 | } | |
3802 | ||
3803 | ret = -EBUSY; | |
3804 | if (fc->phase != FS_CONTEXT_AWAITING_MOUNT) | |
3805 | goto err_unlock; | |
3806 | ||
f7e33bdb JL |
3807 | if (fc->sb_flags & SB_MANDLOCK) |
3808 | warn_mandlock(); | |
93766fbd DH |
3809 | |
3810 | newmount.mnt = vfs_create_mount(fc); | |
3811 | if (IS_ERR(newmount.mnt)) { | |
3812 | ret = PTR_ERR(newmount.mnt); | |
3813 | goto err_unlock; | |
3814 | } | |
3815 | newmount.dentry = dget(fc->root); | |
3816 | newmount.mnt->mnt_flags = mnt_flags; | |
3817 | ||
3818 | /* We've done the mount bit - now move the file context into more or | |
3819 | * less the same state as if we'd done an fspick(). We don't want to | |
3820 | * do any memory allocation or anything like that at this point as we | |
3821 | * don't want to have to handle any errors incurred. | |
3822 | */ | |
3823 | vfs_clean_context(fc); | |
3824 | ||
3825 | ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true); | |
3826 | if (IS_ERR(ns)) { | |
3827 | ret = PTR_ERR(ns); | |
3828 | goto err_path; | |
3829 | } | |
3830 | mnt = real_mount(newmount.mnt); | |
3831 | mnt->mnt_ns = ns; | |
3832 | ns->root = mnt; | |
3833 | ns->mounts = 1; | |
3834 | list_add(&mnt->mnt_list, &ns->list); | |
1b0b9cc8 | 3835 | mntget(newmount.mnt); |
93766fbd DH |
3836 | |
3837 | /* Attach to an apparent O_PATH fd with a note that we need to unmount | |
3838 | * it, not just simply put it. | |
3839 | */ | |
3840 | file = dentry_open(&newmount, O_PATH, fc->cred); | |
3841 | if (IS_ERR(file)) { | |
3842 | dissolve_on_fput(newmount.mnt); | |
3843 | ret = PTR_ERR(file); | |
3844 | goto err_path; | |
3845 | } | |
3846 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
3847 | ||
3848 | ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0); | |
3849 | if (ret >= 0) | |
3850 | fd_install(ret, file); | |
3851 | else | |
3852 | fput(file); | |
3853 | ||
3854 | err_path: | |
3855 | path_put(&newmount); | |
3856 | err_unlock: | |
3857 | mutex_unlock(&fc->uapi_mutex); | |
3858 | err_fsfd: | |
3859 | fdput(f); | |
3860 | return ret; | |
3861 | } | |
3862 | ||
3863 | /* | |
3864 | * Move a mount from one place to another. In combination with | |
3865 | * fsopen()/fsmount() this is used to install a new mount and in combination | |
3866 | * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy | |
3867 | * a mount subtree. | |
2db154b3 DH |
3868 | * |
3869 | * Note the flags value is a combination of MOVE_MOUNT_* flags. | |
3870 | */ | |
3871 | SYSCALL_DEFINE5(move_mount, | |
2658ce09 BD |
3872 | int, from_dfd, const char __user *, from_pathname, |
3873 | int, to_dfd, const char __user *, to_pathname, | |
2db154b3 DH |
3874 | unsigned int, flags) |
3875 | { | |
3876 | struct path from_path, to_path; | |
3877 | unsigned int lflags; | |
3878 | int ret = 0; | |
3879 | ||
3880 | if (!may_mount()) | |
3881 | return -EPERM; | |
3882 | ||
3883 | if (flags & ~MOVE_MOUNT__MASK) | |
3884 | return -EINVAL; | |
3885 | ||
3886 | /* If someone gives a pathname, they aren't permitted to move | |
3887 | * from an fd that requires unmount as we can't get at the flag | |
3888 | * to clear it afterwards. | |
3889 | */ | |
3890 | lflags = 0; | |
3891 | if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3892 | if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3893 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3894 | ||
3895 | ret = user_path_at(from_dfd, from_pathname, lflags, &from_path); | |
3896 | if (ret < 0) | |
3897 | return ret; | |
3898 | ||
3899 | lflags = 0; | |
3900 | if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3901 | if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3902 | if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3903 | ||
3904 | ret = user_path_at(to_dfd, to_pathname, lflags, &to_path); | |
3905 | if (ret < 0) | |
3906 | goto out_from; | |
3907 | ||
3908 | ret = security_move_mount(&from_path, &to_path); | |
3909 | if (ret < 0) | |
3910 | goto out_to; | |
3911 | ||
9ffb14ef PT |
3912 | if (flags & MOVE_MOUNT_SET_GROUP) |
3913 | ret = do_set_group(&from_path, &to_path); | |
3914 | else | |
3915 | ret = do_move_mount(&from_path, &to_path); | |
2db154b3 DH |
3916 | |
3917 | out_to: | |
3918 | path_put(&to_path); | |
3919 | out_from: | |
3920 | path_put(&from_path); | |
3921 | return ret; | |
3922 | } | |
3923 | ||
afac7cba AV |
3924 | /* |
3925 | * Return true if path is reachable from root | |
3926 | * | |
48a066e7 | 3927 | * namespace_sem or mount_lock is held |
afac7cba | 3928 | */ |
643822b4 | 3929 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
3930 | const struct path *root) |
3931 | { | |
643822b4 | 3932 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 3933 | dentry = mnt->mnt_mountpoint; |
0714a533 | 3934 | mnt = mnt->mnt_parent; |
afac7cba | 3935 | } |
643822b4 | 3936 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
3937 | } |
3938 | ||
640eb7e7 | 3939 | bool path_is_under(const struct path *path1, const struct path *path2) |
afac7cba | 3940 | { |
25ab4c9b | 3941 | bool res; |
48a066e7 | 3942 | read_seqlock_excl(&mount_lock); |
643822b4 | 3943 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
48a066e7 | 3944 | read_sequnlock_excl(&mount_lock); |
afac7cba AV |
3945 | return res; |
3946 | } | |
3947 | EXPORT_SYMBOL(path_is_under); | |
3948 | ||
1da177e4 LT |
3949 | /* |
3950 | * pivot_root Semantics: | |
3951 | * Moves the root file system of the current process to the directory put_old, | |
3952 | * makes new_root as the new root file system of the current process, and sets | |
3953 | * root/cwd of all processes which had them on the current root to new_root. | |
3954 | * | |
3955 | * Restrictions: | |
3956 | * The new_root and put_old must be directories, and must not be on the | |
3957 | * same file system as the current process root. The put_old must be | |
3958 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
3959 | * pointed to by put_old must yield the same directory as new_root. No other | |
3960 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
3961 | * | |
4a0d11fa | 3962 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
0c1bc6b8 | 3963 | * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives |
4a0d11fa NB |
3964 | * in this situation. |
3965 | * | |
1da177e4 LT |
3966 | * Notes: |
3967 | * - we don't move root/cwd if they are not at the root (reason: if something | |
3968 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
3969 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
3970 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
3971 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
3972 | * first. | |
3973 | */ | |
3480b257 HC |
3974 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
3975 | const char __user *, put_old) | |
1da177e4 | 3976 | { |
2763d119 AV |
3977 | struct path new, old, root; |
3978 | struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; | |
84d17192 | 3979 | struct mountpoint *old_mp, *root_mp; |
1da177e4 LT |
3980 | int error; |
3981 | ||
9b40bc90 | 3982 | if (!may_mount()) |
1da177e4 LT |
3983 | return -EPERM; |
3984 | ||
ce6595a2 AV |
3985 | error = user_path_at(AT_FDCWD, new_root, |
3986 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new); | |
1da177e4 LT |
3987 | if (error) |
3988 | goto out0; | |
1da177e4 | 3989 | |
ce6595a2 AV |
3990 | error = user_path_at(AT_FDCWD, put_old, |
3991 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old); | |
1da177e4 LT |
3992 | if (error) |
3993 | goto out1; | |
3994 | ||
2d8f3038 | 3995 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
3996 | if (error) |
3997 | goto out2; | |
1da177e4 | 3998 | |
f7ad3c6b | 3999 | get_fs_root(current->fs, &root); |
84d17192 AV |
4000 | old_mp = lock_mount(&old); |
4001 | error = PTR_ERR(old_mp); | |
4002 | if (IS_ERR(old_mp)) | |
b12cea91 AV |
4003 | goto out3; |
4004 | ||
1da177e4 | 4005 | error = -EINVAL; |
419148da AV |
4006 | new_mnt = real_mount(new.mnt); |
4007 | root_mnt = real_mount(root.mnt); | |
84d17192 | 4008 | old_mnt = real_mount(old.mnt); |
2763d119 AV |
4009 | ex_parent = new_mnt->mnt_parent; |
4010 | root_parent = root_mnt->mnt_parent; | |
84d17192 | 4011 | if (IS_MNT_SHARED(old_mnt) || |
2763d119 AV |
4012 | IS_MNT_SHARED(ex_parent) || |
4013 | IS_MNT_SHARED(root_parent)) | |
b12cea91 | 4014 | goto out4; |
143c8c91 | 4015 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
b12cea91 | 4016 | goto out4; |
5ff9d8a6 EB |
4017 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
4018 | goto out4; | |
1da177e4 | 4019 | error = -ENOENT; |
f3da392e | 4020 | if (d_unlinked(new.dentry)) |
b12cea91 | 4021 | goto out4; |
1da177e4 | 4022 | error = -EBUSY; |
84d17192 | 4023 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
b12cea91 | 4024 | goto out4; /* loop, on the same file system */ |
1da177e4 | 4025 | error = -EINVAL; |
8c3ee42e | 4026 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 4027 | goto out4; /* not a mountpoint */ |
676da58d | 4028 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 4029 | goto out4; /* not attached */ |
2d8f3038 | 4030 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 4031 | goto out4; /* not a mountpoint */ |
676da58d | 4032 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 4033 | goto out4; /* not attached */ |
4ac91378 | 4034 | /* make sure we can reach put_old from new_root */ |
84d17192 | 4035 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
b12cea91 | 4036 | goto out4; |
0d082601 EB |
4037 | /* make certain new is below the root */ |
4038 | if (!is_path_reachable(new_mnt, new.dentry, &root)) | |
4039 | goto out4; | |
719ea2fb | 4040 | lock_mount_hash(); |
2763d119 AV |
4041 | umount_mnt(new_mnt); |
4042 | root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ | |
5ff9d8a6 EB |
4043 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
4044 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; | |
4045 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
4046 | } | |
4ac91378 | 4047 | /* mount old root on put_old */ |
84d17192 | 4048 | attach_mnt(root_mnt, old_mnt, old_mp); |
4ac91378 | 4049 | /* mount new_root on / */ |
2763d119 AV |
4050 | attach_mnt(new_mnt, root_parent, root_mp); |
4051 | mnt_add_count(root_parent, -1); | |
6b3286ed | 4052 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
4fed655c EB |
4053 | /* A moved mount should not expire automatically */ |
4054 | list_del_init(&new_mnt->mnt_expire); | |
3895dbf8 | 4055 | put_mountpoint(root_mp); |
719ea2fb | 4056 | unlock_mount_hash(); |
2d8f3038 | 4057 | chroot_fs_refs(&root, &new); |
1da177e4 | 4058 | error = 0; |
b12cea91 | 4059 | out4: |
84d17192 | 4060 | unlock_mount(old_mp); |
2763d119 AV |
4061 | if (!error) |
4062 | mntput_no_expire(ex_parent); | |
b12cea91 | 4063 | out3: |
8c3ee42e | 4064 | path_put(&root); |
b12cea91 | 4065 | out2: |
2d8f3038 | 4066 | path_put(&old); |
1da177e4 | 4067 | out1: |
2d8f3038 | 4068 | path_put(&new); |
1da177e4 | 4069 | out0: |
1da177e4 | 4070 | return error; |
1da177e4 LT |
4071 | } |
4072 | ||
2a186721 CB |
4073 | static unsigned int recalc_flags(struct mount_kattr *kattr, struct mount *mnt) |
4074 | { | |
4075 | unsigned int flags = mnt->mnt.mnt_flags; | |
4076 | ||
4077 | /* flags to clear */ | |
4078 | flags &= ~kattr->attr_clr; | |
4079 | /* flags to raise */ | |
4080 | flags |= kattr->attr_set; | |
4081 | ||
4082 | return flags; | |
4083 | } | |
4084 | ||
9caccd41 CB |
4085 | static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
4086 | { | |
4087 | struct vfsmount *m = &mnt->mnt; | |
bd303368 | 4088 | struct user_namespace *fs_userns = m->mnt_sb->s_user_ns; |
9caccd41 | 4089 | |
256c8aed | 4090 | if (!kattr->mnt_idmap) |
9caccd41 CB |
4091 | return 0; |
4092 | ||
bd303368 CB |
4093 | /* |
4094 | * Creating an idmapped mount with the filesystem wide idmapping | |
4095 | * doesn't make sense so block that. We don't allow mushy semantics. | |
4096 | */ | |
256c8aed | 4097 | if (mnt_idmap_owner(kattr->mnt_idmap) == fs_userns) |
bd303368 CB |
4098 | return -EINVAL; |
4099 | ||
9caccd41 CB |
4100 | /* |
4101 | * Once a mount has been idmapped we don't allow it to change its | |
4102 | * mapping. It makes things simpler and callers can just create | |
4103 | * another bind-mount they can idmap if they want to. | |
4104 | */ | |
bb49e9e7 | 4105 | if (is_idmapped_mnt(m)) |
9caccd41 CB |
4106 | return -EPERM; |
4107 | ||
4108 | /* The underlying filesystem doesn't support idmapped mounts yet. */ | |
4109 | if (!(m->mnt_sb->s_type->fs_flags & FS_ALLOW_IDMAP)) | |
4110 | return -EINVAL; | |
4111 | ||
4112 | /* We're not controlling the superblock. */ | |
bd303368 | 4113 | if (!ns_capable(fs_userns, CAP_SYS_ADMIN)) |
9caccd41 CB |
4114 | return -EPERM; |
4115 | ||
4116 | /* Mount has already been visible in the filesystem hierarchy. */ | |
4117 | if (!is_anon_ns(mnt->mnt_ns)) | |
4118 | return -EINVAL; | |
4119 | ||
4120 | return 0; | |
4121 | } | |
4122 | ||
a26f788b CB |
4123 | /** |
4124 | * mnt_allow_writers() - check whether the attribute change allows writers | |
4125 | * @kattr: the new mount attributes | |
4126 | * @mnt: the mount to which @kattr will be applied | |
4127 | * | |
4128 | * Check whether thew new mount attributes in @kattr allow concurrent writers. | |
4129 | * | |
4130 | * Return: true if writers need to be held, false if not | |
4131 | */ | |
4132 | static inline bool mnt_allow_writers(const struct mount_kattr *kattr, | |
4133 | const struct mount *mnt) | |
2a186721 | 4134 | { |
e1bbcd27 CB |
4135 | return (!(kattr->attr_set & MNT_READONLY) || |
4136 | (mnt->mnt.mnt_flags & MNT_READONLY)) && | |
256c8aed | 4137 | !kattr->mnt_idmap; |
a26f788b | 4138 | } |
2a186721 | 4139 | |
87bb5b60 | 4140 | static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt) |
2a186721 | 4141 | { |
e257039f AV |
4142 | struct mount *m; |
4143 | int err; | |
2a186721 | 4144 | |
e257039f AV |
4145 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
4146 | if (!can_change_locked_flags(m, recalc_flags(kattr, m))) { | |
4147 | err = -EPERM; | |
4148 | break; | |
4149 | } | |
2a186721 | 4150 | |
87bb5b60 CB |
4151 | err = can_idmap_mount(kattr, m); |
4152 | if (err) | |
e257039f | 4153 | break; |
2a186721 | 4154 | |
e257039f AV |
4155 | if (!mnt_allow_writers(kattr, m)) { |
4156 | err = mnt_hold_writers(m); | |
4157 | if (err) | |
4158 | break; | |
2a186721 CB |
4159 | } |
4160 | ||
e257039f AV |
4161 | if (!kattr->recurse) |
4162 | return 0; | |
4163 | } | |
9caccd41 | 4164 | |
e257039f AV |
4165 | if (err) { |
4166 | struct mount *p; | |
2a186721 | 4167 | |
0014edae CB |
4168 | /* |
4169 | * If we had to call mnt_hold_writers() MNT_WRITE_HOLD will | |
4170 | * be set in @mnt_flags. The loop unsets MNT_WRITE_HOLD for all | |
4171 | * mounts and needs to take care to include the first mount. | |
4172 | */ | |
4173 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
e257039f AV |
4174 | /* If we had to hold writers unblock them. */ |
4175 | if (p->mnt.mnt_flags & MNT_WRITE_HOLD) | |
4176 | mnt_unhold_writers(p); | |
0014edae CB |
4177 | |
4178 | /* | |
4179 | * We're done once the first mount we changed got | |
4180 | * MNT_WRITE_HOLD unset. | |
4181 | */ | |
4182 | if (p == m) | |
4183 | break; | |
2a186721 | 4184 | } |
e257039f AV |
4185 | } |
4186 | return err; | |
2a186721 CB |
4187 | } |
4188 | ||
9caccd41 CB |
4189 | static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
4190 | { | |
256c8aed | 4191 | if (!kattr->mnt_idmap) |
9caccd41 CB |
4192 | return; |
4193 | ||
bd303368 | 4194 | /* |
256c8aed CB |
4195 | * Pairs with smp_load_acquire() in mnt_idmap(). |
4196 | * | |
4197 | * Since we only allow a mount to change the idmapping once and | |
4198 | * verified this in can_idmap_mount() we know that the mount has | |
4199 | * @nop_mnt_idmap attached to it. So there's no need to drop any | |
4200 | * references. | |
bd303368 | 4201 | */ |
256c8aed | 4202 | smp_store_release(&mnt->mnt.mnt_idmap, mnt_idmap_get(kattr->mnt_idmap)); |
9caccd41 CB |
4203 | } |
4204 | ||
e257039f | 4205 | static void mount_setattr_commit(struct mount_kattr *kattr, struct mount *mnt) |
2a186721 | 4206 | { |
e257039f | 4207 | struct mount *m; |
2a186721 | 4208 | |
e257039f AV |
4209 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
4210 | unsigned int flags; | |
2a186721 | 4211 | |
e257039f AV |
4212 | do_idmap_mount(kattr, m); |
4213 | flags = recalc_flags(kattr, m); | |
4214 | WRITE_ONCE(m->mnt.mnt_flags, flags); | |
2a186721 | 4215 | |
03b6abee CB |
4216 | /* If we had to hold writers unblock them. */ |
4217 | if (m->mnt.mnt_flags & MNT_WRITE_HOLD) | |
2a186721 CB |
4218 | mnt_unhold_writers(m); |
4219 | ||
e257039f | 4220 | if (kattr->propagation) |
2a186721 | 4221 | change_mnt_propagation(m, kattr->propagation); |
e257039f | 4222 | if (!kattr->recurse) |
2a186721 | 4223 | break; |
e257039f AV |
4224 | } |
4225 | touch_mnt_namespace(mnt->mnt_ns); | |
2a186721 CB |
4226 | } |
4227 | ||
4228 | static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) | |
4229 | { | |
87bb5b60 | 4230 | struct mount *mnt = real_mount(path->mnt); |
2a186721 CB |
4231 | int err = 0; |
4232 | ||
4233 | if (path->dentry != mnt->mnt.mnt_root) | |
4234 | return -EINVAL; | |
4235 | ||
256c8aed CB |
4236 | if (kattr->mnt_userns) { |
4237 | struct mnt_idmap *mnt_idmap; | |
4238 | ||
4239 | mnt_idmap = alloc_mnt_idmap(kattr->mnt_userns); | |
4240 | if (IS_ERR(mnt_idmap)) | |
4241 | return PTR_ERR(mnt_idmap); | |
4242 | kattr->mnt_idmap = mnt_idmap; | |
4243 | } | |
4244 | ||
2a186721 CB |
4245 | if (kattr->propagation) { |
4246 | /* | |
4247 | * Only take namespace_lock() if we're actually changing | |
4248 | * propagation. | |
4249 | */ | |
4250 | namespace_lock(); | |
4251 | if (kattr->propagation == MS_SHARED) { | |
4252 | err = invent_group_ids(mnt, kattr->recurse); | |
4253 | if (err) { | |
4254 | namespace_unlock(); | |
4255 | return err; | |
4256 | } | |
4257 | } | |
4258 | } | |
4259 | ||
87bb5b60 | 4260 | err = -EINVAL; |
2a186721 CB |
4261 | lock_mount_hash(); |
4262 | ||
87bb5b60 CB |
4263 | /* Ensure that this isn't anything purely vfs internal. */ |
4264 | if (!is_mounted(&mnt->mnt)) | |
4265 | goto out; | |
4266 | ||
2a186721 | 4267 | /* |
87bb5b60 CB |
4268 | * If this is an attached mount make sure it's located in the callers |
4269 | * mount namespace. If it's not don't let the caller interact with it. | |
4270 | * If this is a detached mount make sure it has an anonymous mount | |
4271 | * namespace attached to it, i.e. we've created it via OPEN_TREE_CLONE. | |
2a186721 | 4272 | */ |
87bb5b60 CB |
4273 | if (!(mnt_has_parent(mnt) ? check_mnt(mnt) : is_anon_ns(mnt->mnt_ns))) |
4274 | goto out; | |
2a186721 | 4275 | |
87bb5b60 CB |
4276 | /* |
4277 | * First, we get the mount tree in a shape where we can change mount | |
4278 | * properties without failure. If we succeeded to do so we commit all | |
4279 | * changes and if we failed we clean up. | |
4280 | */ | |
4281 | err = mount_setattr_prepare(kattr, mnt); | |
e257039f AV |
4282 | if (!err) |
4283 | mount_setattr_commit(kattr, mnt); | |
2a186721 | 4284 | |
87bb5b60 | 4285 | out: |
2a186721 CB |
4286 | unlock_mount_hash(); |
4287 | ||
4288 | if (kattr->propagation) { | |
4289 | namespace_unlock(); | |
4290 | if (err) | |
4291 | cleanup_group_ids(mnt, NULL); | |
4292 | } | |
4293 | ||
4294 | return err; | |
4295 | } | |
4296 | ||
9caccd41 CB |
4297 | static int build_mount_idmapped(const struct mount_attr *attr, size_t usize, |
4298 | struct mount_kattr *kattr, unsigned int flags) | |
4299 | { | |
4300 | int err = 0; | |
4301 | struct ns_common *ns; | |
4302 | struct user_namespace *mnt_userns; | |
4303 | struct file *file; | |
4304 | ||
4305 | if (!((attr->attr_set | attr->attr_clr) & MOUNT_ATTR_IDMAP)) | |
4306 | return 0; | |
4307 | ||
4308 | /* | |
4309 | * We currently do not support clearing an idmapped mount. If this ever | |
4310 | * is a use-case we can revisit this but for now let's keep it simple | |
4311 | * and not allow it. | |
4312 | */ | |
4313 | if (attr->attr_clr & MOUNT_ATTR_IDMAP) | |
4314 | return -EINVAL; | |
4315 | ||
4316 | if (attr->userns_fd > INT_MAX) | |
4317 | return -EINVAL; | |
4318 | ||
4319 | file = fget(attr->userns_fd); | |
4320 | if (!file) | |
4321 | return -EBADF; | |
4322 | ||
4323 | if (!proc_ns_file(file)) { | |
4324 | err = -EINVAL; | |
4325 | goto out_fput; | |
4326 | } | |
4327 | ||
4328 | ns = get_proc_ns(file_inode(file)); | |
4329 | if (ns->ops->type != CLONE_NEWUSER) { | |
4330 | err = -EINVAL; | |
4331 | goto out_fput; | |
4332 | } | |
4333 | ||
4334 | /* | |
bd303368 CB |
4335 | * The initial idmapping cannot be used to create an idmapped |
4336 | * mount. We use the initial idmapping as an indicator of a mount | |
4337 | * that is not idmapped. It can simply be passed into helpers that | |
4338 | * are aware of idmapped mounts as a convenient shortcut. A user | |
4339 | * can just create a dedicated identity mapping to achieve the same | |
4340 | * result. | |
9caccd41 CB |
4341 | */ |
4342 | mnt_userns = container_of(ns, struct user_namespace, ns); | |
bd303368 | 4343 | if (initial_idmapping(mnt_userns)) { |
9caccd41 CB |
4344 | err = -EPERM; |
4345 | goto out_fput; | |
4346 | } | |
bf1ac16e SF |
4347 | |
4348 | /* We're not controlling the target namespace. */ | |
4349 | if (!ns_capable(mnt_userns, CAP_SYS_ADMIN)) { | |
4350 | err = -EPERM; | |
4351 | goto out_fput; | |
4352 | } | |
4353 | ||
9caccd41 CB |
4354 | kattr->mnt_userns = get_user_ns(mnt_userns); |
4355 | ||
4356 | out_fput: | |
4357 | fput(file); | |
4358 | return err; | |
4359 | } | |
4360 | ||
4361 | static int build_mount_kattr(const struct mount_attr *attr, size_t usize, | |
2a186721 CB |
4362 | struct mount_kattr *kattr, unsigned int flags) |
4363 | { | |
4364 | unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; | |
4365 | ||
4366 | if (flags & AT_NO_AUTOMOUNT) | |
4367 | lookup_flags &= ~LOOKUP_AUTOMOUNT; | |
4368 | if (flags & AT_SYMLINK_NOFOLLOW) | |
4369 | lookup_flags &= ~LOOKUP_FOLLOW; | |
4370 | if (flags & AT_EMPTY_PATH) | |
4371 | lookup_flags |= LOOKUP_EMPTY; | |
4372 | ||
4373 | *kattr = (struct mount_kattr) { | |
4374 | .lookup_flags = lookup_flags, | |
4375 | .recurse = !!(flags & AT_RECURSIVE), | |
4376 | }; | |
4377 | ||
4378 | if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS) | |
4379 | return -EINVAL; | |
4380 | if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1) | |
4381 | return -EINVAL; | |
4382 | kattr->propagation = attr->propagation; | |
4383 | ||
4384 | if ((attr->attr_set | attr->attr_clr) & ~MOUNT_SETATTR_VALID_FLAGS) | |
4385 | return -EINVAL; | |
4386 | ||
2a186721 CB |
4387 | kattr->attr_set = attr_flags_to_mnt_flags(attr->attr_set); |
4388 | kattr->attr_clr = attr_flags_to_mnt_flags(attr->attr_clr); | |
4389 | ||
4390 | /* | |
4391 | * Since the MOUNT_ATTR_<atime> values are an enum, not a bitmap, | |
4392 | * users wanting to transition to a different atime setting cannot | |
4393 | * simply specify the atime setting in @attr_set, but must also | |
4394 | * specify MOUNT_ATTR__ATIME in the @attr_clr field. | |
4395 | * So ensure that MOUNT_ATTR__ATIME can't be partially set in | |
4396 | * @attr_clr and that @attr_set can't have any atime bits set if | |
4397 | * MOUNT_ATTR__ATIME isn't set in @attr_clr. | |
4398 | */ | |
4399 | if (attr->attr_clr & MOUNT_ATTR__ATIME) { | |
4400 | if ((attr->attr_clr & MOUNT_ATTR__ATIME) != MOUNT_ATTR__ATIME) | |
4401 | return -EINVAL; | |
4402 | ||
4403 | /* | |
4404 | * Clear all previous time settings as they are mutually | |
4405 | * exclusive. | |
4406 | */ | |
4407 | kattr->attr_clr |= MNT_RELATIME | MNT_NOATIME; | |
4408 | switch (attr->attr_set & MOUNT_ATTR__ATIME) { | |
4409 | case MOUNT_ATTR_RELATIME: | |
4410 | kattr->attr_set |= MNT_RELATIME; | |
4411 | break; | |
4412 | case MOUNT_ATTR_NOATIME: | |
4413 | kattr->attr_set |= MNT_NOATIME; | |
4414 | break; | |
4415 | case MOUNT_ATTR_STRICTATIME: | |
4416 | break; | |
4417 | default: | |
4418 | return -EINVAL; | |
4419 | } | |
4420 | } else { | |
4421 | if (attr->attr_set & MOUNT_ATTR__ATIME) | |
4422 | return -EINVAL; | |
4423 | } | |
4424 | ||
9caccd41 CB |
4425 | return build_mount_idmapped(attr, usize, kattr, flags); |
4426 | } | |
4427 | ||
4428 | static void finish_mount_kattr(struct mount_kattr *kattr) | |
4429 | { | |
4430 | put_user_ns(kattr->mnt_userns); | |
4431 | kattr->mnt_userns = NULL; | |
256c8aed CB |
4432 | |
4433 | if (kattr->mnt_idmap) | |
4434 | mnt_idmap_put(kattr->mnt_idmap); | |
2a186721 CB |
4435 | } |
4436 | ||
4437 | SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path, | |
4438 | unsigned int, flags, struct mount_attr __user *, uattr, | |
4439 | size_t, usize) | |
4440 | { | |
4441 | int err; | |
4442 | struct path target; | |
4443 | struct mount_attr attr; | |
4444 | struct mount_kattr kattr; | |
4445 | ||
4446 | BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0); | |
4447 | ||
4448 | if (flags & ~(AT_EMPTY_PATH | | |
4449 | AT_RECURSIVE | | |
4450 | AT_SYMLINK_NOFOLLOW | | |
4451 | AT_NO_AUTOMOUNT)) | |
4452 | return -EINVAL; | |
4453 | ||
4454 | if (unlikely(usize > PAGE_SIZE)) | |
4455 | return -E2BIG; | |
4456 | if (unlikely(usize < MOUNT_ATTR_SIZE_VER0)) | |
4457 | return -EINVAL; | |
4458 | ||
4459 | if (!may_mount()) | |
4460 | return -EPERM; | |
4461 | ||
4462 | err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize); | |
4463 | if (err) | |
4464 | return err; | |
4465 | ||
4466 | /* Don't bother walking through the mounts if this is a nop. */ | |
4467 | if (attr.attr_set == 0 && | |
4468 | attr.attr_clr == 0 && | |
4469 | attr.propagation == 0) | |
4470 | return 0; | |
4471 | ||
9caccd41 | 4472 | err = build_mount_kattr(&attr, usize, &kattr, flags); |
2a186721 CB |
4473 | if (err) |
4474 | return err; | |
4475 | ||
4476 | err = user_path_at(dfd, path, kattr.lookup_flags, &target); | |
012e3322 CB |
4477 | if (!err) { |
4478 | err = do_mount_setattr(&target, &kattr); | |
4479 | path_put(&target); | |
4480 | } | |
9caccd41 | 4481 | finish_mount_kattr(&kattr); |
2a186721 CB |
4482 | return err; |
4483 | } | |
4484 | ||
1da177e4 LT |
4485 | static void __init init_mount_tree(void) |
4486 | { | |
4487 | struct vfsmount *mnt; | |
74e83122 | 4488 | struct mount *m; |
6b3286ed | 4489 | struct mnt_namespace *ns; |
ac748a09 | 4490 | struct path root; |
1da177e4 | 4491 | |
fd3e007f | 4492 | mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL); |
1da177e4 LT |
4493 | if (IS_ERR(mnt)) |
4494 | panic("Can't create rootfs"); | |
b3e19d92 | 4495 | |
74e83122 | 4496 | ns = alloc_mnt_ns(&init_user_ns, false); |
3b22edc5 | 4497 | if (IS_ERR(ns)) |
1da177e4 | 4498 | panic("Can't allocate initial namespace"); |
74e83122 AV |
4499 | m = real_mount(mnt); |
4500 | m->mnt_ns = ns; | |
4501 | ns->root = m; | |
4502 | ns->mounts = 1; | |
4503 | list_add(&m->mnt_list, &ns->list); | |
6b3286ed KK |
4504 | init_task.nsproxy->mnt_ns = ns; |
4505 | get_mnt_ns(ns); | |
4506 | ||
be08d6d2 AV |
4507 | root.mnt = mnt; |
4508 | root.dentry = mnt->mnt_root; | |
da362b09 | 4509 | mnt->mnt_flags |= MNT_LOCKED; |
ac748a09 JB |
4510 | |
4511 | set_fs_pwd(current->fs, &root); | |
4512 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
4513 | } |
4514 | ||
74bf17cf | 4515 | void __init mnt_init(void) |
1da177e4 | 4516 | { |
15a67dd8 | 4517 | int err; |
1da177e4 | 4518 | |
7d6fec45 | 4519 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
79f6540b | 4520 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); |
1da177e4 | 4521 | |
0818bf27 | 4522 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
38129a13 | 4523 | sizeof(struct hlist_head), |
0818bf27 | 4524 | mhash_entries, 19, |
3d375d78 | 4525 | HASH_ZERO, |
0818bf27 AV |
4526 | &m_hash_shift, &m_hash_mask, 0, 0); |
4527 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", | |
4528 | sizeof(struct hlist_head), | |
4529 | mphash_entries, 19, | |
3d375d78 | 4530 | HASH_ZERO, |
0818bf27 | 4531 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
1da177e4 | 4532 | |
84d17192 | 4533 | if (!mount_hashtable || !mountpoint_hashtable) |
1da177e4 LT |
4534 | panic("Failed to allocate mount hash table\n"); |
4535 | ||
4b93dc9b TH |
4536 | kernfs_init(); |
4537 | ||
15a67dd8 RD |
4538 | err = sysfs_init(); |
4539 | if (err) | |
4540 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 4541 | __func__, err); |
00d26666 GKH |
4542 | fs_kobj = kobject_create_and_add("fs", NULL); |
4543 | if (!fs_kobj) | |
8e24eea7 | 4544 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
037f11b4 | 4545 | shmem_init(); |
1da177e4 LT |
4546 | init_rootfs(); |
4547 | init_mount_tree(); | |
4548 | } | |
4549 | ||
616511d0 | 4550 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 4551 | { |
1a7b8969 | 4552 | if (!refcount_dec_and_test(&ns->ns.count)) |
616511d0 | 4553 | return; |
7b00ed6f | 4554 | drop_collected_mounts(&ns->root->mnt); |
771b1371 | 4555 | free_mnt_ns(ns); |
1da177e4 | 4556 | } |
9d412a43 | 4557 | |
d911b458 | 4558 | struct vfsmount *kern_mount(struct file_system_type *type) |
9d412a43 | 4559 | { |
423e0ab0 | 4560 | struct vfsmount *mnt; |
d911b458 | 4561 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
423e0ab0 TC |
4562 | if (!IS_ERR(mnt)) { |
4563 | /* | |
4564 | * it is a longterm mount, don't release mnt until | |
4565 | * we unmount before file sys is unregistered | |
4566 | */ | |
f7a99c5b | 4567 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
423e0ab0 TC |
4568 | } |
4569 | return mnt; | |
9d412a43 | 4570 | } |
d911b458 | 4571 | EXPORT_SYMBOL_GPL(kern_mount); |
423e0ab0 TC |
4572 | |
4573 | void kern_unmount(struct vfsmount *mnt) | |
4574 | { | |
4575 | /* release long term mount so mount point can be released */ | |
4576 | if (!IS_ERR_OR_NULL(mnt)) { | |
f7a99c5b | 4577 | real_mount(mnt)->mnt_ns = NULL; |
48a066e7 | 4578 | synchronize_rcu(); /* yecchhh... */ |
423e0ab0 TC |
4579 | mntput(mnt); |
4580 | } | |
4581 | } | |
4582 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 | 4583 | |
df820f8d MS |
4584 | void kern_unmount_array(struct vfsmount *mnt[], unsigned int num) |
4585 | { | |
4586 | unsigned int i; | |
4587 | ||
4588 | for (i = 0; i < num; i++) | |
4589 | if (mnt[i]) | |
4590 | real_mount(mnt[i])->mnt_ns = NULL; | |
4591 | synchronize_rcu_expedited(); | |
4592 | for (i = 0; i < num; i++) | |
4593 | mntput(mnt[i]); | |
4594 | } | |
4595 | EXPORT_SYMBOL(kern_unmount_array); | |
4596 | ||
02125a82 AV |
4597 | bool our_mnt(struct vfsmount *mnt) |
4598 | { | |
143c8c91 | 4599 | return check_mnt(real_mount(mnt)); |
02125a82 | 4600 | } |
8823c079 | 4601 | |
3151527e EB |
4602 | bool current_chrooted(void) |
4603 | { | |
4604 | /* Does the current process have a non-standard root */ | |
4605 | struct path ns_root; | |
4606 | struct path fs_root; | |
4607 | bool chrooted; | |
4608 | ||
4609 | /* Find the namespace root */ | |
4610 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; | |
4611 | ns_root.dentry = ns_root.mnt->mnt_root; | |
4612 | path_get(&ns_root); | |
4613 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) | |
4614 | ; | |
4615 | ||
4616 | get_fs_root(current->fs, &fs_root); | |
4617 | ||
4618 | chrooted = !path_equal(&fs_root, &ns_root); | |
4619 | ||
4620 | path_put(&fs_root); | |
4621 | path_put(&ns_root); | |
4622 | ||
4623 | return chrooted; | |
4624 | } | |
4625 | ||
132e4608 DH |
4626 | static bool mnt_already_visible(struct mnt_namespace *ns, |
4627 | const struct super_block *sb, | |
8654df4e | 4628 | int *new_mnt_flags) |
87a8ebd6 | 4629 | { |
8c6cf9cc | 4630 | int new_flags = *new_mnt_flags; |
87a8ebd6 | 4631 | struct mount *mnt; |
e51db735 | 4632 | bool visible = false; |
87a8ebd6 | 4633 | |
44bb4385 | 4634 | down_read(&namespace_sem); |
9f6c61f9 | 4635 | lock_ns_list(ns); |
87a8ebd6 | 4636 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
e51db735 | 4637 | struct mount *child; |
77b1a97d EB |
4638 | int mnt_flags; |
4639 | ||
9f6c61f9 MS |
4640 | if (mnt_is_cursor(mnt)) |
4641 | continue; | |
4642 | ||
132e4608 | 4643 | if (mnt->mnt.mnt_sb->s_type != sb->s_type) |
e51db735 EB |
4644 | continue; |
4645 | ||
7e96c1b0 EB |
4646 | /* This mount is not fully visible if it's root directory |
4647 | * is not the root directory of the filesystem. | |
4648 | */ | |
4649 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) | |
4650 | continue; | |
4651 | ||
a1935c17 | 4652 | /* A local view of the mount flags */ |
77b1a97d | 4653 | mnt_flags = mnt->mnt.mnt_flags; |
77b1a97d | 4654 | |
695e9df0 | 4655 | /* Don't miss readonly hidden in the superblock flags */ |
bc98a42c | 4656 | if (sb_rdonly(mnt->mnt.mnt_sb)) |
695e9df0 EB |
4657 | mnt_flags |= MNT_LOCK_READONLY; |
4658 | ||
8c6cf9cc EB |
4659 | /* Verify the mount flags are equal to or more permissive |
4660 | * than the proposed new mount. | |
4661 | */ | |
77b1a97d | 4662 | if ((mnt_flags & MNT_LOCK_READONLY) && |
8c6cf9cc EB |
4663 | !(new_flags & MNT_READONLY)) |
4664 | continue; | |
77b1a97d EB |
4665 | if ((mnt_flags & MNT_LOCK_ATIME) && |
4666 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) | |
8c6cf9cc EB |
4667 | continue; |
4668 | ||
ceeb0e5d EB |
4669 | /* This mount is not fully visible if there are any |
4670 | * locked child mounts that cover anything except for | |
4671 | * empty directories. | |
e51db735 EB |
4672 | */ |
4673 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
4674 | struct inode *inode = child->mnt_mountpoint->d_inode; | |
ceeb0e5d | 4675 | /* Only worry about locked mounts */ |
d71ed6c9 | 4676 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
ceeb0e5d | 4677 | continue; |
7236c85e EB |
4678 | /* Is the directory permanetly empty? */ |
4679 | if (!is_empty_dir_inode(inode)) | |
e51db735 | 4680 | goto next; |
87a8ebd6 | 4681 | } |
8c6cf9cc | 4682 | /* Preserve the locked attributes */ |
77b1a97d | 4683 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
77b1a97d | 4684 | MNT_LOCK_ATIME); |
e51db735 EB |
4685 | visible = true; |
4686 | goto found; | |
4687 | next: ; | |
87a8ebd6 | 4688 | } |
e51db735 | 4689 | found: |
9f6c61f9 | 4690 | unlock_ns_list(ns); |
44bb4385 | 4691 | up_read(&namespace_sem); |
e51db735 | 4692 | return visible; |
87a8ebd6 EB |
4693 | } |
4694 | ||
132e4608 | 4695 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags) |
8654df4e | 4696 | { |
a1935c17 | 4697 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
8654df4e EB |
4698 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
4699 | unsigned long s_iflags; | |
4700 | ||
4701 | if (ns->user_ns == &init_user_ns) | |
4702 | return false; | |
4703 | ||
4704 | /* Can this filesystem be too revealing? */ | |
132e4608 | 4705 | s_iflags = sb->s_iflags; |
8654df4e EB |
4706 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
4707 | return false; | |
4708 | ||
a1935c17 EB |
4709 | if ((s_iflags & required_iflags) != required_iflags) { |
4710 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", | |
4711 | required_iflags); | |
4712 | return true; | |
4713 | } | |
4714 | ||
132e4608 | 4715 | return !mnt_already_visible(ns, sb, new_mnt_flags); |
8654df4e EB |
4716 | } |
4717 | ||
380cf5ba AL |
4718 | bool mnt_may_suid(struct vfsmount *mnt) |
4719 | { | |
4720 | /* | |
4721 | * Foreign mounts (accessed via fchdir or through /proc | |
4722 | * symlinks) are always treated as if they are nosuid. This | |
4723 | * prevents namespaces from trusting potentially unsafe | |
4724 | * suid/sgid bits, file caps, or security labels that originate | |
4725 | * in other namespaces. | |
4726 | */ | |
4727 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && | |
4728 | current_in_userns(mnt->mnt_sb->s_user_ns); | |
4729 | } | |
4730 | ||
64964528 | 4731 | static struct ns_common *mntns_get(struct task_struct *task) |
8823c079 | 4732 | { |
58be2825 | 4733 | struct ns_common *ns = NULL; |
8823c079 EB |
4734 | struct nsproxy *nsproxy; |
4735 | ||
728dba3a EB |
4736 | task_lock(task); |
4737 | nsproxy = task->nsproxy; | |
8823c079 | 4738 | if (nsproxy) { |
58be2825 AV |
4739 | ns = &nsproxy->mnt_ns->ns; |
4740 | get_mnt_ns(to_mnt_ns(ns)); | |
8823c079 | 4741 | } |
728dba3a | 4742 | task_unlock(task); |
8823c079 EB |
4743 | |
4744 | return ns; | |
4745 | } | |
4746 | ||
64964528 | 4747 | static void mntns_put(struct ns_common *ns) |
8823c079 | 4748 | { |
58be2825 | 4749 | put_mnt_ns(to_mnt_ns(ns)); |
8823c079 EB |
4750 | } |
4751 | ||
f2a8d52e | 4752 | static int mntns_install(struct nsset *nsset, struct ns_common *ns) |
8823c079 | 4753 | { |
f2a8d52e CB |
4754 | struct nsproxy *nsproxy = nsset->nsproxy; |
4755 | struct fs_struct *fs = nsset->fs; | |
4f757f3c | 4756 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns; |
f2a8d52e | 4757 | struct user_namespace *user_ns = nsset->cred->user_ns; |
8823c079 | 4758 | struct path root; |
4f757f3c | 4759 | int err; |
8823c079 | 4760 | |
0c55cfc4 | 4761 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
f2a8d52e CB |
4762 | !ns_capable(user_ns, CAP_SYS_CHROOT) || |
4763 | !ns_capable(user_ns, CAP_SYS_ADMIN)) | |
ae11e0f1 | 4764 | return -EPERM; |
8823c079 | 4765 | |
74e83122 AV |
4766 | if (is_anon_ns(mnt_ns)) |
4767 | return -EINVAL; | |
4768 | ||
8823c079 EB |
4769 | if (fs->users != 1) |
4770 | return -EINVAL; | |
4771 | ||
4772 | get_mnt_ns(mnt_ns); | |
4f757f3c | 4773 | old_mnt_ns = nsproxy->mnt_ns; |
8823c079 EB |
4774 | nsproxy->mnt_ns = mnt_ns; |
4775 | ||
4776 | /* Find the root */ | |
4f757f3c AV |
4777 | err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt, |
4778 | "/", LOOKUP_DOWN, &root); | |
4779 | if (err) { | |
4780 | /* revert to old namespace */ | |
4781 | nsproxy->mnt_ns = old_mnt_ns; | |
4782 | put_mnt_ns(mnt_ns); | |
4783 | return err; | |
4784 | } | |
8823c079 | 4785 | |
4068367c AV |
4786 | put_mnt_ns(old_mnt_ns); |
4787 | ||
8823c079 EB |
4788 | /* Update the pwd and root */ |
4789 | set_fs_pwd(fs, &root); | |
4790 | set_fs_root(fs, &root); | |
4791 | ||
4792 | path_put(&root); | |
4793 | return 0; | |
4794 | } | |
4795 | ||
bcac25a5 AV |
4796 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
4797 | { | |
4798 | return to_mnt_ns(ns)->user_ns; | |
4799 | } | |
4800 | ||
8823c079 EB |
4801 | const struct proc_ns_operations mntns_operations = { |
4802 | .name = "mnt", | |
4803 | .type = CLONE_NEWNS, | |
4804 | .get = mntns_get, | |
4805 | .put = mntns_put, | |
4806 | .install = mntns_install, | |
bcac25a5 | 4807 | .owner = mntns_owner, |
8823c079 | 4808 | }; |
ab171b95 LC |
4809 | |
4810 | #ifdef CONFIG_SYSCTL | |
4811 | static struct ctl_table fs_namespace_sysctls[] = { | |
4812 | { | |
4813 | .procname = "mount-max", | |
4814 | .data = &sysctl_mount_max, | |
4815 | .maxlen = sizeof(unsigned int), | |
4816 | .mode = 0644, | |
4817 | .proc_handler = proc_dointvec_minmax, | |
4818 | .extra1 = SYSCTL_ONE, | |
4819 | }, | |
4820 | { } | |
4821 | }; | |
4822 | ||
4823 | static int __init init_fs_namespace_sysctls(void) | |
4824 | { | |
4825 | register_sysctl_init("fs", fs_namespace_sysctls); | |
4826 | return 0; | |
4827 | } | |
4828 | fs_initcall(init_fs_namespace_sysctls); | |
4829 | ||
4830 | #endif /* CONFIG_SYSCTL */ |