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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namespace.c | |
3 | * | |
4 | * (C) Copyright Al Viro 2000, 2001 | |
5 | * Released under GPL v2. | |
6 | * | |
7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. | |
8 | * Heavily rewritten. | |
9 | */ | |
10 | ||
1da177e4 LT |
11 | #include <linux/syscalls.h> |
12 | #include <linux/slab.h> | |
13 | #include <linux/sched.h> | |
99b7db7b NP |
14 | #include <linux/spinlock.h> |
15 | #include <linux/percpu.h> | |
1da177e4 | 16 | #include <linux/init.h> |
15a67dd8 | 17 | #include <linux/kernel.h> |
1da177e4 | 18 | #include <linux/acct.h> |
16f7e0fe | 19 | #include <linux/capability.h> |
3d733633 | 20 | #include <linux/cpumask.h> |
1da177e4 | 21 | #include <linux/module.h> |
f20a9ead | 22 | #include <linux/sysfs.h> |
1da177e4 | 23 | #include <linux/seq_file.h> |
6b3286ed | 24 | #include <linux/mnt_namespace.h> |
1da177e4 | 25 | #include <linux/namei.h> |
b43f3cbd | 26 | #include <linux/nsproxy.h> |
1da177e4 LT |
27 | #include <linux/security.h> |
28 | #include <linux/mount.h> | |
07f3f05c | 29 | #include <linux/ramfs.h> |
13f14b4d | 30 | #include <linux/log2.h> |
73cd49ec | 31 | #include <linux/idr.h> |
5ad4e53b | 32 | #include <linux/fs_struct.h> |
2504c5d6 | 33 | #include <linux/fsnotify.h> |
1da177e4 LT |
34 | #include <asm/uaccess.h> |
35 | #include <asm/unistd.h> | |
07b20889 | 36 | #include "pnode.h" |
948730b0 | 37 | #include "internal.h" |
1da177e4 | 38 | |
13f14b4d ED |
39 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
40 | #define HASH_SIZE (1UL << HASH_SHIFT) | |
41 | ||
5addc5dd | 42 | static int event; |
73cd49ec | 43 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 44 | static DEFINE_IDA(mnt_group_ida); |
99b7db7b | 45 | static DEFINE_SPINLOCK(mnt_id_lock); |
f21f6220 AV |
46 | static int mnt_id_start = 0; |
47 | static int mnt_group_start = 1; | |
1da177e4 | 48 | |
fa3536cc | 49 | static struct list_head *mount_hashtable __read_mostly; |
e18b890b | 50 | static struct kmem_cache *mnt_cache __read_mostly; |
390c6843 | 51 | static struct rw_semaphore namespace_sem; |
1da177e4 | 52 | |
f87fd4c2 | 53 | /* /sys/fs */ |
00d26666 GKH |
54 | struct kobject *fs_kobj; |
55 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 56 | |
99b7db7b NP |
57 | /* |
58 | * vfsmount lock may be taken for read to prevent changes to the | |
59 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
60 | * up the tree. | |
61 | * | |
62 | * It should be taken for write in all cases where the vfsmount | |
63 | * tree or hash is modified or when a vfsmount structure is modified. | |
64 | */ | |
65 | DEFINE_BRLOCK(vfsmount_lock); | |
66 | ||
1da177e4 LT |
67 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
68 | { | |
b58fed8b RP |
69 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
70 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
13f14b4d ED |
71 | tmp = tmp + (tmp >> HASH_SHIFT); |
72 | return tmp & (HASH_SIZE - 1); | |
1da177e4 LT |
73 | } |
74 | ||
3d733633 DH |
75 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
76 | ||
99b7db7b NP |
77 | /* |
78 | * allocation is serialized by namespace_sem, but we need the spinlock to | |
79 | * serialize with freeing. | |
80 | */ | |
73cd49ec MS |
81 | static int mnt_alloc_id(struct vfsmount *mnt) |
82 | { | |
83 | int res; | |
84 | ||
85 | retry: | |
86 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); | |
99b7db7b | 87 | spin_lock(&mnt_id_lock); |
f21f6220 AV |
88 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
89 | if (!res) | |
90 | mnt_id_start = mnt->mnt_id + 1; | |
99b7db7b | 91 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
92 | if (res == -EAGAIN) |
93 | goto retry; | |
94 | ||
95 | return res; | |
96 | } | |
97 | ||
98 | static void mnt_free_id(struct vfsmount *mnt) | |
99 | { | |
f21f6220 | 100 | int id = mnt->mnt_id; |
99b7db7b | 101 | spin_lock(&mnt_id_lock); |
f21f6220 AV |
102 | ida_remove(&mnt_id_ida, id); |
103 | if (mnt_id_start > id) | |
104 | mnt_id_start = id; | |
99b7db7b | 105 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
106 | } |
107 | ||
719f5d7f MS |
108 | /* |
109 | * Allocate a new peer group ID | |
110 | * | |
111 | * mnt_group_ida is protected by namespace_sem | |
112 | */ | |
113 | static int mnt_alloc_group_id(struct vfsmount *mnt) | |
114 | { | |
f21f6220 AV |
115 | int res; |
116 | ||
719f5d7f MS |
117 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
118 | return -ENOMEM; | |
119 | ||
f21f6220 AV |
120 | res = ida_get_new_above(&mnt_group_ida, |
121 | mnt_group_start, | |
122 | &mnt->mnt_group_id); | |
123 | if (!res) | |
124 | mnt_group_start = mnt->mnt_group_id + 1; | |
125 | ||
126 | return res; | |
719f5d7f MS |
127 | } |
128 | ||
129 | /* | |
130 | * Release a peer group ID | |
131 | */ | |
132 | void mnt_release_group_id(struct vfsmount *mnt) | |
133 | { | |
f21f6220 AV |
134 | int id = mnt->mnt_group_id; |
135 | ida_remove(&mnt_group_ida, id); | |
136 | if (mnt_group_start > id) | |
137 | mnt_group_start = id; | |
719f5d7f MS |
138 | mnt->mnt_group_id = 0; |
139 | } | |
140 | ||
1da177e4 LT |
141 | struct vfsmount *alloc_vfsmnt(const char *name) |
142 | { | |
c3762229 | 143 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
1da177e4 | 144 | if (mnt) { |
73cd49ec MS |
145 | int err; |
146 | ||
147 | err = mnt_alloc_id(mnt); | |
88b38782 LZ |
148 | if (err) |
149 | goto out_free_cache; | |
150 | ||
151 | if (name) { | |
152 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); | |
153 | if (!mnt->mnt_devname) | |
154 | goto out_free_id; | |
73cd49ec MS |
155 | } |
156 | ||
b58fed8b | 157 | atomic_set(&mnt->mnt_count, 1); |
1da177e4 LT |
158 | INIT_LIST_HEAD(&mnt->mnt_hash); |
159 | INIT_LIST_HEAD(&mnt->mnt_child); | |
160 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
161 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 162 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 163 | INIT_LIST_HEAD(&mnt->mnt_share); |
a58b0eb8 RP |
164 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
165 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
2504c5d6 AG |
166 | #ifdef CONFIG_FSNOTIFY |
167 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); | |
168 | #endif | |
d3ef3d73 NP |
169 | #ifdef CONFIG_SMP |
170 | mnt->mnt_writers = alloc_percpu(int); | |
171 | if (!mnt->mnt_writers) | |
172 | goto out_free_devname; | |
173 | #else | |
174 | mnt->mnt_writers = 0; | |
175 | #endif | |
1da177e4 LT |
176 | } |
177 | return mnt; | |
88b38782 | 178 | |
d3ef3d73 NP |
179 | #ifdef CONFIG_SMP |
180 | out_free_devname: | |
181 | kfree(mnt->mnt_devname); | |
182 | #endif | |
88b38782 LZ |
183 | out_free_id: |
184 | mnt_free_id(mnt); | |
185 | out_free_cache: | |
186 | kmem_cache_free(mnt_cache, mnt); | |
187 | return NULL; | |
1da177e4 LT |
188 | } |
189 | ||
3d733633 DH |
190 | /* |
191 | * Most r/o checks on a fs are for operations that take | |
192 | * discrete amounts of time, like a write() or unlink(). | |
193 | * We must keep track of when those operations start | |
194 | * (for permission checks) and when they end, so that | |
195 | * we can determine when writes are able to occur to | |
196 | * a filesystem. | |
197 | */ | |
198 | /* | |
199 | * __mnt_is_readonly: check whether a mount is read-only | |
200 | * @mnt: the mount to check for its write status | |
201 | * | |
202 | * This shouldn't be used directly ouside of the VFS. | |
203 | * It does not guarantee that the filesystem will stay | |
204 | * r/w, just that it is right *now*. This can not and | |
205 | * should not be used in place of IS_RDONLY(inode). | |
206 | * mnt_want/drop_write() will _keep_ the filesystem | |
207 | * r/w. | |
208 | */ | |
209 | int __mnt_is_readonly(struct vfsmount *mnt) | |
210 | { | |
2e4b7fcd DH |
211 | if (mnt->mnt_flags & MNT_READONLY) |
212 | return 1; | |
213 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
214 | return 1; | |
215 | return 0; | |
3d733633 DH |
216 | } |
217 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
218 | ||
d3ef3d73 NP |
219 | static inline void inc_mnt_writers(struct vfsmount *mnt) |
220 | { | |
221 | #ifdef CONFIG_SMP | |
222 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++; | |
223 | #else | |
224 | mnt->mnt_writers++; | |
225 | #endif | |
226 | } | |
3d733633 | 227 | |
d3ef3d73 | 228 | static inline void dec_mnt_writers(struct vfsmount *mnt) |
3d733633 | 229 | { |
d3ef3d73 NP |
230 | #ifdef CONFIG_SMP |
231 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--; | |
232 | #else | |
233 | mnt->mnt_writers--; | |
234 | #endif | |
3d733633 | 235 | } |
3d733633 | 236 | |
d3ef3d73 | 237 | static unsigned int count_mnt_writers(struct vfsmount *mnt) |
3d733633 | 238 | { |
d3ef3d73 NP |
239 | #ifdef CONFIG_SMP |
240 | unsigned int count = 0; | |
3d733633 | 241 | int cpu; |
3d733633 DH |
242 | |
243 | for_each_possible_cpu(cpu) { | |
d3ef3d73 | 244 | count += *per_cpu_ptr(mnt->mnt_writers, cpu); |
3d733633 | 245 | } |
3d733633 | 246 | |
d3ef3d73 NP |
247 | return count; |
248 | #else | |
249 | return mnt->mnt_writers; | |
250 | #endif | |
3d733633 DH |
251 | } |
252 | ||
8366025e DH |
253 | /* |
254 | * Most r/o checks on a fs are for operations that take | |
255 | * discrete amounts of time, like a write() or unlink(). | |
256 | * We must keep track of when those operations start | |
257 | * (for permission checks) and when they end, so that | |
258 | * we can determine when writes are able to occur to | |
259 | * a filesystem. | |
260 | */ | |
261 | /** | |
262 | * mnt_want_write - get write access to a mount | |
263 | * @mnt: the mount on which to take a write | |
264 | * | |
265 | * This tells the low-level filesystem that a write is | |
266 | * about to be performed to it, and makes sure that | |
267 | * writes are allowed before returning success. When | |
268 | * the write operation is finished, mnt_drop_write() | |
269 | * must be called. This is effectively a refcount. | |
270 | */ | |
271 | int mnt_want_write(struct vfsmount *mnt) | |
272 | { | |
3d733633 | 273 | int ret = 0; |
3d733633 | 274 | |
d3ef3d73 NP |
275 | preempt_disable(); |
276 | inc_mnt_writers(mnt); | |
277 | /* | |
278 | * The store to inc_mnt_writers must be visible before we pass | |
279 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our | |
280 | * incremented count after it has set MNT_WRITE_HOLD. | |
281 | */ | |
282 | smp_mb(); | |
283 | while (mnt->mnt_flags & MNT_WRITE_HOLD) | |
284 | cpu_relax(); | |
285 | /* | |
286 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
287 | * be set to match its requirements. So we must not load that until | |
288 | * MNT_WRITE_HOLD is cleared. | |
289 | */ | |
290 | smp_rmb(); | |
3d733633 | 291 | if (__mnt_is_readonly(mnt)) { |
d3ef3d73 | 292 | dec_mnt_writers(mnt); |
3d733633 DH |
293 | ret = -EROFS; |
294 | goto out; | |
295 | } | |
3d733633 | 296 | out: |
d3ef3d73 | 297 | preempt_enable(); |
3d733633 | 298 | return ret; |
8366025e DH |
299 | } |
300 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
301 | ||
96029c4e NP |
302 | /** |
303 | * mnt_clone_write - get write access to a mount | |
304 | * @mnt: the mount on which to take a write | |
305 | * | |
306 | * This is effectively like mnt_want_write, except | |
307 | * it must only be used to take an extra write reference | |
308 | * on a mountpoint that we already know has a write reference | |
309 | * on it. This allows some optimisation. | |
310 | * | |
311 | * After finished, mnt_drop_write must be called as usual to | |
312 | * drop the reference. | |
313 | */ | |
314 | int mnt_clone_write(struct vfsmount *mnt) | |
315 | { | |
316 | /* superblock may be r/o */ | |
317 | if (__mnt_is_readonly(mnt)) | |
318 | return -EROFS; | |
319 | preempt_disable(); | |
320 | inc_mnt_writers(mnt); | |
321 | preempt_enable(); | |
322 | return 0; | |
323 | } | |
324 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
325 | ||
326 | /** | |
327 | * mnt_want_write_file - get write access to a file's mount | |
328 | * @file: the file who's mount on which to take a write | |
329 | * | |
330 | * This is like mnt_want_write, but it takes a file and can | |
331 | * do some optimisations if the file is open for write already | |
332 | */ | |
333 | int mnt_want_write_file(struct file *file) | |
334 | { | |
2d8dd38a OH |
335 | struct inode *inode = file->f_dentry->d_inode; |
336 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) | |
96029c4e NP |
337 | return mnt_want_write(file->f_path.mnt); |
338 | else | |
339 | return mnt_clone_write(file->f_path.mnt); | |
340 | } | |
341 | EXPORT_SYMBOL_GPL(mnt_want_write_file); | |
342 | ||
8366025e DH |
343 | /** |
344 | * mnt_drop_write - give up write access to a mount | |
345 | * @mnt: the mount on which to give up write access | |
346 | * | |
347 | * Tells the low-level filesystem that we are done | |
348 | * performing writes to it. Must be matched with | |
349 | * mnt_want_write() call above. | |
350 | */ | |
351 | void mnt_drop_write(struct vfsmount *mnt) | |
352 | { | |
d3ef3d73 NP |
353 | preempt_disable(); |
354 | dec_mnt_writers(mnt); | |
355 | preempt_enable(); | |
8366025e DH |
356 | } |
357 | EXPORT_SYMBOL_GPL(mnt_drop_write); | |
358 | ||
2e4b7fcd | 359 | static int mnt_make_readonly(struct vfsmount *mnt) |
8366025e | 360 | { |
3d733633 DH |
361 | int ret = 0; |
362 | ||
99b7db7b | 363 | br_write_lock(vfsmount_lock); |
d3ef3d73 | 364 | mnt->mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 365 | /* |
d3ef3d73 NP |
366 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
367 | * should be visible before we do. | |
3d733633 | 368 | */ |
d3ef3d73 NP |
369 | smp_mb(); |
370 | ||
3d733633 | 371 | /* |
d3ef3d73 NP |
372 | * With writers on hold, if this value is zero, then there are |
373 | * definitely no active writers (although held writers may subsequently | |
374 | * increment the count, they'll have to wait, and decrement it after | |
375 | * seeing MNT_READONLY). | |
376 | * | |
377 | * It is OK to have counter incremented on one CPU and decremented on | |
378 | * another: the sum will add up correctly. The danger would be when we | |
379 | * sum up each counter, if we read a counter before it is incremented, | |
380 | * but then read another CPU's count which it has been subsequently | |
381 | * decremented from -- we would see more decrements than we should. | |
382 | * MNT_WRITE_HOLD protects against this scenario, because | |
383 | * mnt_want_write first increments count, then smp_mb, then spins on | |
384 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
385 | * we're counting up here. | |
3d733633 | 386 | */ |
d3ef3d73 NP |
387 | if (count_mnt_writers(mnt) > 0) |
388 | ret = -EBUSY; | |
389 | else | |
2e4b7fcd | 390 | mnt->mnt_flags |= MNT_READONLY; |
d3ef3d73 NP |
391 | /* |
392 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
393 | * that become unheld will see MNT_READONLY. | |
394 | */ | |
395 | smp_wmb(); | |
396 | mnt->mnt_flags &= ~MNT_WRITE_HOLD; | |
99b7db7b | 397 | br_write_unlock(vfsmount_lock); |
3d733633 | 398 | return ret; |
8366025e | 399 | } |
8366025e | 400 | |
2e4b7fcd DH |
401 | static void __mnt_unmake_readonly(struct vfsmount *mnt) |
402 | { | |
99b7db7b | 403 | br_write_lock(vfsmount_lock); |
2e4b7fcd | 404 | mnt->mnt_flags &= ~MNT_READONLY; |
99b7db7b | 405 | br_write_unlock(vfsmount_lock); |
2e4b7fcd DH |
406 | } |
407 | ||
a3ec947c | 408 | void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
454e2398 DH |
409 | { |
410 | mnt->mnt_sb = sb; | |
411 | mnt->mnt_root = dget(sb->s_root); | |
454e2398 DH |
412 | } |
413 | ||
414 | EXPORT_SYMBOL(simple_set_mnt); | |
415 | ||
1da177e4 LT |
416 | void free_vfsmnt(struct vfsmount *mnt) |
417 | { | |
418 | kfree(mnt->mnt_devname); | |
73cd49ec | 419 | mnt_free_id(mnt); |
d3ef3d73 NP |
420 | #ifdef CONFIG_SMP |
421 | free_percpu(mnt->mnt_writers); | |
422 | #endif | |
1da177e4 LT |
423 | kmem_cache_free(mnt_cache, mnt); |
424 | } | |
425 | ||
426 | /* | |
a05964f3 RP |
427 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
428 | * @dir. If @dir is set return the first mount else return the last mount. | |
99b7db7b | 429 | * vfsmount_lock must be held for read or write. |
1da177e4 | 430 | */ |
a05964f3 RP |
431 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
432 | int dir) | |
1da177e4 | 433 | { |
b58fed8b RP |
434 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
435 | struct list_head *tmp = head; | |
1da177e4 LT |
436 | struct vfsmount *p, *found = NULL; |
437 | ||
1da177e4 | 438 | for (;;) { |
a05964f3 | 439 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
440 | p = NULL; |
441 | if (tmp == head) | |
442 | break; | |
443 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
444 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
a05964f3 | 445 | found = p; |
1da177e4 LT |
446 | break; |
447 | } | |
448 | } | |
1da177e4 LT |
449 | return found; |
450 | } | |
451 | ||
a05964f3 RP |
452 | /* |
453 | * lookup_mnt increments the ref count before returning | |
454 | * the vfsmount struct. | |
455 | */ | |
1c755af4 | 456 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 RP |
457 | { |
458 | struct vfsmount *child_mnt; | |
99b7db7b NP |
459 | |
460 | br_read_lock(vfsmount_lock); | |
1c755af4 | 461 | if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) |
a05964f3 | 462 | mntget(child_mnt); |
99b7db7b | 463 | br_read_unlock(vfsmount_lock); |
a05964f3 RP |
464 | return child_mnt; |
465 | } | |
466 | ||
1da177e4 LT |
467 | static inline int check_mnt(struct vfsmount *mnt) |
468 | { | |
6b3286ed | 469 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
470 | } |
471 | ||
99b7db7b NP |
472 | /* |
473 | * vfsmount lock must be held for write | |
474 | */ | |
6b3286ed | 475 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
476 | { |
477 | if (ns) { | |
478 | ns->event = ++event; | |
479 | wake_up_interruptible(&ns->poll); | |
480 | } | |
481 | } | |
482 | ||
99b7db7b NP |
483 | /* |
484 | * vfsmount lock must be held for write | |
485 | */ | |
6b3286ed | 486 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
487 | { |
488 | if (ns && ns->event != event) { | |
489 | ns->event = event; | |
490 | wake_up_interruptible(&ns->poll); | |
491 | } | |
492 | } | |
493 | ||
5f57cbcc NP |
494 | /* |
495 | * Clear dentry's mounted state if it has no remaining mounts. | |
496 | * vfsmount_lock must be held for write. | |
497 | */ | |
498 | static void dentry_reset_mounted(struct vfsmount *mnt, struct dentry *dentry) | |
499 | { | |
500 | unsigned u; | |
501 | ||
502 | for (u = 0; u < HASH_SIZE; u++) { | |
503 | struct vfsmount *p; | |
504 | ||
505 | list_for_each_entry(p, &mount_hashtable[u], mnt_hash) { | |
506 | if (p->mnt_mountpoint == dentry) | |
507 | return; | |
508 | } | |
509 | } | |
510 | spin_lock(&dentry->d_lock); | |
511 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
512 | spin_unlock(&dentry->d_lock); | |
513 | } | |
514 | ||
99b7db7b NP |
515 | /* |
516 | * vfsmount lock must be held for write | |
517 | */ | |
1a390689 | 518 | static void detach_mnt(struct vfsmount *mnt, struct path *old_path) |
1da177e4 | 519 | { |
1a390689 AV |
520 | old_path->dentry = mnt->mnt_mountpoint; |
521 | old_path->mnt = mnt->mnt_parent; | |
1da177e4 LT |
522 | mnt->mnt_parent = mnt; |
523 | mnt->mnt_mountpoint = mnt->mnt_root; | |
524 | list_del_init(&mnt->mnt_child); | |
525 | list_del_init(&mnt->mnt_hash); | |
5f57cbcc | 526 | dentry_reset_mounted(old_path->mnt, old_path->dentry); |
1da177e4 LT |
527 | } |
528 | ||
99b7db7b NP |
529 | /* |
530 | * vfsmount lock must be held for write | |
531 | */ | |
b90fa9ae RP |
532 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
533 | struct vfsmount *child_mnt) | |
534 | { | |
535 | child_mnt->mnt_parent = mntget(mnt); | |
536 | child_mnt->mnt_mountpoint = dget(dentry); | |
5f57cbcc NP |
537 | spin_lock(&dentry->d_lock); |
538 | dentry->d_flags |= DCACHE_MOUNTED; | |
539 | spin_unlock(&dentry->d_lock); | |
b90fa9ae RP |
540 | } |
541 | ||
99b7db7b NP |
542 | /* |
543 | * vfsmount lock must be held for write | |
544 | */ | |
1a390689 | 545 | static void attach_mnt(struct vfsmount *mnt, struct path *path) |
1da177e4 | 546 | { |
1a390689 | 547 | mnt_set_mountpoint(path->mnt, path->dentry, mnt); |
b90fa9ae | 548 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
1a390689 AV |
549 | hash(path->mnt, path->dentry)); |
550 | list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); | |
b90fa9ae RP |
551 | } |
552 | ||
553 | /* | |
99b7db7b | 554 | * vfsmount lock must be held for write |
b90fa9ae RP |
555 | */ |
556 | static void commit_tree(struct vfsmount *mnt) | |
557 | { | |
558 | struct vfsmount *parent = mnt->mnt_parent; | |
559 | struct vfsmount *m; | |
560 | LIST_HEAD(head); | |
6b3286ed | 561 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae RP |
562 | |
563 | BUG_ON(parent == mnt); | |
564 | ||
565 | list_add_tail(&head, &mnt->mnt_list); | |
566 | list_for_each_entry(m, &head, mnt_list) | |
6b3286ed | 567 | m->mnt_ns = n; |
b90fa9ae RP |
568 | list_splice(&head, n->list.prev); |
569 | ||
570 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
571 | hash(parent, mnt->mnt_mountpoint)); | |
572 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
6b3286ed | 573 | touch_mnt_namespace(n); |
1da177e4 LT |
574 | } |
575 | ||
576 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
577 | { | |
578 | struct list_head *next = p->mnt_mounts.next; | |
579 | if (next == &p->mnt_mounts) { | |
580 | while (1) { | |
581 | if (p == root) | |
582 | return NULL; | |
583 | next = p->mnt_child.next; | |
584 | if (next != &p->mnt_parent->mnt_mounts) | |
585 | break; | |
586 | p = p->mnt_parent; | |
587 | } | |
588 | } | |
589 | return list_entry(next, struct vfsmount, mnt_child); | |
590 | } | |
591 | ||
9676f0c6 RP |
592 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
593 | { | |
594 | struct list_head *prev = p->mnt_mounts.prev; | |
595 | while (prev != &p->mnt_mounts) { | |
596 | p = list_entry(prev, struct vfsmount, mnt_child); | |
597 | prev = p->mnt_mounts.prev; | |
598 | } | |
599 | return p; | |
600 | } | |
601 | ||
36341f64 RP |
602 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
603 | int flag) | |
1da177e4 LT |
604 | { |
605 | struct super_block *sb = old->mnt_sb; | |
606 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
607 | ||
608 | if (mnt) { | |
719f5d7f MS |
609 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
610 | mnt->mnt_group_id = 0; /* not a peer of original */ | |
611 | else | |
612 | mnt->mnt_group_id = old->mnt_group_id; | |
613 | ||
614 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { | |
615 | int err = mnt_alloc_group_id(mnt); | |
616 | if (err) | |
617 | goto out_free; | |
618 | } | |
619 | ||
be1a16a0 | 620 | mnt->mnt_flags = old->mnt_flags & ~MNT_WRITE_HOLD; |
1da177e4 LT |
621 | atomic_inc(&sb->s_active); |
622 | mnt->mnt_sb = sb; | |
623 | mnt->mnt_root = dget(root); | |
624 | mnt->mnt_mountpoint = mnt->mnt_root; | |
625 | mnt->mnt_parent = mnt; | |
b90fa9ae | 626 | |
5afe0022 RP |
627 | if (flag & CL_SLAVE) { |
628 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); | |
629 | mnt->mnt_master = old; | |
630 | CLEAR_MNT_SHARED(mnt); | |
8aec0809 | 631 | } else if (!(flag & CL_PRIVATE)) { |
796a6b52 | 632 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
5afe0022 RP |
633 | list_add(&mnt->mnt_share, &old->mnt_share); |
634 | if (IS_MNT_SLAVE(old)) | |
635 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
636 | mnt->mnt_master = old->mnt_master; | |
637 | } | |
b90fa9ae RP |
638 | if (flag & CL_MAKE_SHARED) |
639 | set_mnt_shared(mnt); | |
1da177e4 LT |
640 | |
641 | /* stick the duplicate mount on the same expiry list | |
642 | * as the original if that was on one */ | |
36341f64 | 643 | if (flag & CL_EXPIRE) { |
36341f64 RP |
644 | if (!list_empty(&old->mnt_expire)) |
645 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
36341f64 | 646 | } |
1da177e4 LT |
647 | } |
648 | return mnt; | |
719f5d7f MS |
649 | |
650 | out_free: | |
651 | free_vfsmnt(mnt); | |
652 | return NULL; | |
1da177e4 LT |
653 | } |
654 | ||
7b7b1ace | 655 | static inline void __mntput(struct vfsmount *mnt) |
1da177e4 LT |
656 | { |
657 | struct super_block *sb = mnt->mnt_sb; | |
3d733633 DH |
658 | /* |
659 | * This probably indicates that somebody messed | |
660 | * up a mnt_want/drop_write() pair. If this | |
661 | * happens, the filesystem was probably unable | |
662 | * to make r/w->r/o transitions. | |
663 | */ | |
d3ef3d73 NP |
664 | /* |
665 | * atomic_dec_and_lock() used to deal with ->mnt_count decrements | |
666 | * provides barriers, so count_mnt_writers() below is safe. AV | |
667 | */ | |
668 | WARN_ON(count_mnt_writers(mnt)); | |
ca9c726e | 669 | fsnotify_vfsmount_delete(mnt); |
1da177e4 LT |
670 | dput(mnt->mnt_root); |
671 | free_vfsmnt(mnt); | |
672 | deactivate_super(sb); | |
673 | } | |
674 | ||
7b7b1ace AV |
675 | void mntput_no_expire(struct vfsmount *mnt) |
676 | { | |
677 | repeat: | |
99b7db7b NP |
678 | if (atomic_add_unless(&mnt->mnt_count, -1, 1)) |
679 | return; | |
680 | br_write_lock(vfsmount_lock); | |
681 | if (!atomic_dec_and_test(&mnt->mnt_count)) { | |
682 | br_write_unlock(vfsmount_lock); | |
683 | return; | |
684 | } | |
685 | if (likely(!mnt->mnt_pinned)) { | |
686 | br_write_unlock(vfsmount_lock); | |
687 | __mntput(mnt); | |
688 | return; | |
7b7b1ace | 689 | } |
99b7db7b NP |
690 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); |
691 | mnt->mnt_pinned = 0; | |
692 | br_write_unlock(vfsmount_lock); | |
693 | acct_auto_close_mnt(mnt); | |
694 | goto repeat; | |
7b7b1ace | 695 | } |
7b7b1ace AV |
696 | EXPORT_SYMBOL(mntput_no_expire); |
697 | ||
698 | void mnt_pin(struct vfsmount *mnt) | |
699 | { | |
99b7db7b | 700 | br_write_lock(vfsmount_lock); |
7b7b1ace | 701 | mnt->mnt_pinned++; |
99b7db7b | 702 | br_write_unlock(vfsmount_lock); |
7b7b1ace AV |
703 | } |
704 | ||
705 | EXPORT_SYMBOL(mnt_pin); | |
706 | ||
707 | void mnt_unpin(struct vfsmount *mnt) | |
708 | { | |
99b7db7b | 709 | br_write_lock(vfsmount_lock); |
7b7b1ace AV |
710 | if (mnt->mnt_pinned) { |
711 | atomic_inc(&mnt->mnt_count); | |
712 | mnt->mnt_pinned--; | |
713 | } | |
99b7db7b | 714 | br_write_unlock(vfsmount_lock); |
7b7b1ace AV |
715 | } |
716 | ||
717 | EXPORT_SYMBOL(mnt_unpin); | |
1da177e4 | 718 | |
b3b304a2 MS |
719 | static inline void mangle(struct seq_file *m, const char *s) |
720 | { | |
721 | seq_escape(m, s, " \t\n\\"); | |
722 | } | |
723 | ||
724 | /* | |
725 | * Simple .show_options callback for filesystems which don't want to | |
726 | * implement more complex mount option showing. | |
727 | * | |
728 | * See also save_mount_options(). | |
729 | */ | |
730 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) | |
731 | { | |
2a32cebd AV |
732 | const char *options; |
733 | ||
734 | rcu_read_lock(); | |
735 | options = rcu_dereference(mnt->mnt_sb->s_options); | |
b3b304a2 MS |
736 | |
737 | if (options != NULL && options[0]) { | |
738 | seq_putc(m, ','); | |
739 | mangle(m, options); | |
740 | } | |
2a32cebd | 741 | rcu_read_unlock(); |
b3b304a2 MS |
742 | |
743 | return 0; | |
744 | } | |
745 | EXPORT_SYMBOL(generic_show_options); | |
746 | ||
747 | /* | |
748 | * If filesystem uses generic_show_options(), this function should be | |
749 | * called from the fill_super() callback. | |
750 | * | |
751 | * The .remount_fs callback usually needs to be handled in a special | |
752 | * way, to make sure, that previous options are not overwritten if the | |
753 | * remount fails. | |
754 | * | |
755 | * Also note, that if the filesystem's .remount_fs function doesn't | |
756 | * reset all options to their default value, but changes only newly | |
757 | * given options, then the displayed options will not reflect reality | |
758 | * any more. | |
759 | */ | |
760 | void save_mount_options(struct super_block *sb, char *options) | |
761 | { | |
2a32cebd AV |
762 | BUG_ON(sb->s_options); |
763 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
764 | } |
765 | EXPORT_SYMBOL(save_mount_options); | |
766 | ||
2a32cebd AV |
767 | void replace_mount_options(struct super_block *sb, char *options) |
768 | { | |
769 | char *old = sb->s_options; | |
770 | rcu_assign_pointer(sb->s_options, options); | |
771 | if (old) { | |
772 | synchronize_rcu(); | |
773 | kfree(old); | |
774 | } | |
775 | } | |
776 | EXPORT_SYMBOL(replace_mount_options); | |
777 | ||
a1a2c409 | 778 | #ifdef CONFIG_PROC_FS |
1da177e4 LT |
779 | /* iterator */ |
780 | static void *m_start(struct seq_file *m, loff_t *pos) | |
781 | { | |
a1a2c409 | 782 | struct proc_mounts *p = m->private; |
1da177e4 | 783 | |
390c6843 | 784 | down_read(&namespace_sem); |
a1a2c409 | 785 | return seq_list_start(&p->ns->list, *pos); |
1da177e4 LT |
786 | } |
787 | ||
788 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
789 | { | |
a1a2c409 | 790 | struct proc_mounts *p = m->private; |
b0765fb8 | 791 | |
a1a2c409 | 792 | return seq_list_next(v, &p->ns->list, pos); |
1da177e4 LT |
793 | } |
794 | ||
795 | static void m_stop(struct seq_file *m, void *v) | |
796 | { | |
390c6843 | 797 | up_read(&namespace_sem); |
1da177e4 LT |
798 | } |
799 | ||
9f5596af AV |
800 | int mnt_had_events(struct proc_mounts *p) |
801 | { | |
802 | struct mnt_namespace *ns = p->ns; | |
803 | int res = 0; | |
804 | ||
99b7db7b | 805 | br_read_lock(vfsmount_lock); |
9f5596af AV |
806 | if (p->event != ns->event) { |
807 | p->event = ns->event; | |
808 | res = 1; | |
809 | } | |
99b7db7b | 810 | br_read_unlock(vfsmount_lock); |
9f5596af AV |
811 | |
812 | return res; | |
813 | } | |
814 | ||
2d4d4864 RP |
815 | struct proc_fs_info { |
816 | int flag; | |
817 | const char *str; | |
818 | }; | |
819 | ||
2069f457 | 820 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
1da177e4 | 821 | { |
2d4d4864 | 822 | static const struct proc_fs_info fs_info[] = { |
1da177e4 LT |
823 | { MS_SYNCHRONOUS, ",sync" }, |
824 | { MS_DIRSYNC, ",dirsync" }, | |
825 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
826 | { 0, NULL } |
827 | }; | |
2d4d4864 RP |
828 | const struct proc_fs_info *fs_infop; |
829 | ||
830 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
831 | if (sb->s_flags & fs_infop->flag) | |
832 | seq_puts(m, fs_infop->str); | |
833 | } | |
2069f457 EP |
834 | |
835 | return security_sb_show_options(m, sb); | |
2d4d4864 RP |
836 | } |
837 | ||
838 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) | |
839 | { | |
840 | static const struct proc_fs_info mnt_info[] = { | |
1da177e4 LT |
841 | { MNT_NOSUID, ",nosuid" }, |
842 | { MNT_NODEV, ",nodev" }, | |
843 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
844 | { MNT_NOATIME, ",noatime" }, |
845 | { MNT_NODIRATIME, ",nodiratime" }, | |
47ae32d6 | 846 | { MNT_RELATIME, ",relatime" }, |
1da177e4 LT |
847 | { 0, NULL } |
848 | }; | |
2d4d4864 RP |
849 | const struct proc_fs_info *fs_infop; |
850 | ||
851 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
852 | if (mnt->mnt_flags & fs_infop->flag) | |
853 | seq_puts(m, fs_infop->str); | |
854 | } | |
855 | } | |
856 | ||
857 | static void show_type(struct seq_file *m, struct super_block *sb) | |
858 | { | |
859 | mangle(m, sb->s_type->name); | |
860 | if (sb->s_subtype && sb->s_subtype[0]) { | |
861 | seq_putc(m, '.'); | |
862 | mangle(m, sb->s_subtype); | |
863 | } | |
864 | } | |
865 | ||
866 | static int show_vfsmnt(struct seq_file *m, void *v) | |
867 | { | |
868 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
869 | int err = 0; | |
c32c2f63 | 870 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
1da177e4 LT |
871 | |
872 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
873 | seq_putc(m, ' '); | |
c32c2f63 | 874 | seq_path(m, &mnt_path, " \t\n\\"); |
1da177e4 | 875 | seq_putc(m, ' '); |
2d4d4864 | 876 | show_type(m, mnt->mnt_sb); |
2e4b7fcd | 877 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
2069f457 EP |
878 | err = show_sb_opts(m, mnt->mnt_sb); |
879 | if (err) | |
880 | goto out; | |
2d4d4864 | 881 | show_mnt_opts(m, mnt); |
1da177e4 LT |
882 | if (mnt->mnt_sb->s_op->show_options) |
883 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
884 | seq_puts(m, " 0 0\n"); | |
2069f457 | 885 | out: |
1da177e4 LT |
886 | return err; |
887 | } | |
888 | ||
a1a2c409 | 889 | const struct seq_operations mounts_op = { |
1da177e4 LT |
890 | .start = m_start, |
891 | .next = m_next, | |
892 | .stop = m_stop, | |
893 | .show = show_vfsmnt | |
894 | }; | |
895 | ||
2d4d4864 RP |
896 | static int show_mountinfo(struct seq_file *m, void *v) |
897 | { | |
898 | struct proc_mounts *p = m->private; | |
899 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
900 | struct super_block *sb = mnt->mnt_sb; | |
901 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; | |
902 | struct path root = p->root; | |
903 | int err = 0; | |
904 | ||
905 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, | |
906 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); | |
907 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); | |
908 | seq_putc(m, ' '); | |
909 | seq_path_root(m, &mnt_path, &root, " \t\n\\"); | |
910 | if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { | |
911 | /* | |
912 | * Mountpoint is outside root, discard that one. Ugly, | |
913 | * but less so than trying to do that in iterator in a | |
914 | * race-free way (due to renames). | |
915 | */ | |
916 | return SEQ_SKIP; | |
917 | } | |
918 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); | |
919 | show_mnt_opts(m, mnt); | |
920 | ||
921 | /* Tagged fields ("foo:X" or "bar") */ | |
922 | if (IS_MNT_SHARED(mnt)) | |
923 | seq_printf(m, " shared:%i", mnt->mnt_group_id); | |
97e7e0f7 MS |
924 | if (IS_MNT_SLAVE(mnt)) { |
925 | int master = mnt->mnt_master->mnt_group_id; | |
926 | int dom = get_dominating_id(mnt, &p->root); | |
927 | seq_printf(m, " master:%i", master); | |
928 | if (dom && dom != master) | |
929 | seq_printf(m, " propagate_from:%i", dom); | |
930 | } | |
2d4d4864 RP |
931 | if (IS_MNT_UNBINDABLE(mnt)) |
932 | seq_puts(m, " unbindable"); | |
933 | ||
934 | /* Filesystem specific data */ | |
935 | seq_puts(m, " - "); | |
936 | show_type(m, sb); | |
937 | seq_putc(m, ' '); | |
938 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
939 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); | |
2069f457 EP |
940 | err = show_sb_opts(m, sb); |
941 | if (err) | |
942 | goto out; | |
2d4d4864 RP |
943 | if (sb->s_op->show_options) |
944 | err = sb->s_op->show_options(m, mnt); | |
945 | seq_putc(m, '\n'); | |
2069f457 | 946 | out: |
2d4d4864 RP |
947 | return err; |
948 | } | |
949 | ||
950 | const struct seq_operations mountinfo_op = { | |
951 | .start = m_start, | |
952 | .next = m_next, | |
953 | .stop = m_stop, | |
954 | .show = show_mountinfo, | |
955 | }; | |
956 | ||
b4629fe2 CL |
957 | static int show_vfsstat(struct seq_file *m, void *v) |
958 | { | |
b0765fb8 | 959 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
c32c2f63 | 960 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
b4629fe2 CL |
961 | int err = 0; |
962 | ||
963 | /* device */ | |
964 | if (mnt->mnt_devname) { | |
965 | seq_puts(m, "device "); | |
966 | mangle(m, mnt->mnt_devname); | |
967 | } else | |
968 | seq_puts(m, "no device"); | |
969 | ||
970 | /* mount point */ | |
971 | seq_puts(m, " mounted on "); | |
c32c2f63 | 972 | seq_path(m, &mnt_path, " \t\n\\"); |
b4629fe2 CL |
973 | seq_putc(m, ' '); |
974 | ||
975 | /* file system type */ | |
976 | seq_puts(m, "with fstype "); | |
2d4d4864 | 977 | show_type(m, mnt->mnt_sb); |
b4629fe2 CL |
978 | |
979 | /* optional statistics */ | |
980 | if (mnt->mnt_sb->s_op->show_stats) { | |
981 | seq_putc(m, ' '); | |
982 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); | |
983 | } | |
984 | ||
985 | seq_putc(m, '\n'); | |
986 | return err; | |
987 | } | |
988 | ||
a1a2c409 | 989 | const struct seq_operations mountstats_op = { |
b4629fe2 CL |
990 | .start = m_start, |
991 | .next = m_next, | |
992 | .stop = m_stop, | |
993 | .show = show_vfsstat, | |
994 | }; | |
a1a2c409 | 995 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 996 | |
1da177e4 LT |
997 | /** |
998 | * may_umount_tree - check if a mount tree is busy | |
999 | * @mnt: root of mount tree | |
1000 | * | |
1001 | * This is called to check if a tree of mounts has any | |
1002 | * open files, pwds, chroots or sub mounts that are | |
1003 | * busy. | |
1004 | */ | |
1005 | int may_umount_tree(struct vfsmount *mnt) | |
1006 | { | |
36341f64 RP |
1007 | int actual_refs = 0; |
1008 | int minimum_refs = 0; | |
1009 | struct vfsmount *p; | |
1da177e4 | 1010 | |
99b7db7b | 1011 | br_read_lock(vfsmount_lock); |
36341f64 | 1012 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1da177e4 LT |
1013 | actual_refs += atomic_read(&p->mnt_count); |
1014 | minimum_refs += 2; | |
1da177e4 | 1015 | } |
99b7db7b | 1016 | br_read_unlock(vfsmount_lock); |
1da177e4 LT |
1017 | |
1018 | if (actual_refs > minimum_refs) | |
e3474a8e | 1019 | return 0; |
1da177e4 | 1020 | |
e3474a8e | 1021 | return 1; |
1da177e4 LT |
1022 | } |
1023 | ||
1024 | EXPORT_SYMBOL(may_umount_tree); | |
1025 | ||
1026 | /** | |
1027 | * may_umount - check if a mount point is busy | |
1028 | * @mnt: root of mount | |
1029 | * | |
1030 | * This is called to check if a mount point has any | |
1031 | * open files, pwds, chroots or sub mounts. If the | |
1032 | * mount has sub mounts this will return busy | |
1033 | * regardless of whether the sub mounts are busy. | |
1034 | * | |
1035 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1036 | * give false negatives. The main reason why it's here is that we need | |
1037 | * a non-destructive way to look for easily umountable filesystems. | |
1038 | */ | |
1039 | int may_umount(struct vfsmount *mnt) | |
1040 | { | |
e3474a8e | 1041 | int ret = 1; |
8ad08d8a | 1042 | down_read(&namespace_sem); |
99b7db7b | 1043 | br_read_lock(vfsmount_lock); |
a05964f3 | 1044 | if (propagate_mount_busy(mnt, 2)) |
e3474a8e | 1045 | ret = 0; |
99b7db7b | 1046 | br_read_unlock(vfsmount_lock); |
8ad08d8a | 1047 | up_read(&namespace_sem); |
a05964f3 | 1048 | return ret; |
1da177e4 LT |
1049 | } |
1050 | ||
1051 | EXPORT_SYMBOL(may_umount); | |
1052 | ||
b90fa9ae | 1053 | void release_mounts(struct list_head *head) |
70fbcdf4 RP |
1054 | { |
1055 | struct vfsmount *mnt; | |
bf066c7d | 1056 | while (!list_empty(head)) { |
b5e61818 | 1057 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
70fbcdf4 RP |
1058 | list_del_init(&mnt->mnt_hash); |
1059 | if (mnt->mnt_parent != mnt) { | |
1060 | struct dentry *dentry; | |
1061 | struct vfsmount *m; | |
99b7db7b NP |
1062 | |
1063 | br_write_lock(vfsmount_lock); | |
70fbcdf4 RP |
1064 | dentry = mnt->mnt_mountpoint; |
1065 | m = mnt->mnt_parent; | |
1066 | mnt->mnt_mountpoint = mnt->mnt_root; | |
1067 | mnt->mnt_parent = mnt; | |
7c4b93d8 | 1068 | m->mnt_ghosts--; |
99b7db7b | 1069 | br_write_unlock(vfsmount_lock); |
70fbcdf4 RP |
1070 | dput(dentry); |
1071 | mntput(m); | |
1072 | } | |
1073 | mntput(mnt); | |
1074 | } | |
1075 | } | |
1076 | ||
99b7db7b NP |
1077 | /* |
1078 | * vfsmount lock must be held for write | |
1079 | * namespace_sem must be held for write | |
1080 | */ | |
a05964f3 | 1081 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
1da177e4 LT |
1082 | { |
1083 | struct vfsmount *p; | |
1da177e4 | 1084 | |
1bfba4e8 AM |
1085 | for (p = mnt; p; p = next_mnt(p, mnt)) |
1086 | list_move(&p->mnt_hash, kill); | |
1da177e4 | 1087 | |
a05964f3 RP |
1088 | if (propagate) |
1089 | propagate_umount(kill); | |
1090 | ||
70fbcdf4 RP |
1091 | list_for_each_entry(p, kill, mnt_hash) { |
1092 | list_del_init(&p->mnt_expire); | |
1093 | list_del_init(&p->mnt_list); | |
6b3286ed KK |
1094 | __touch_mnt_namespace(p->mnt_ns); |
1095 | p->mnt_ns = NULL; | |
70fbcdf4 | 1096 | list_del_init(&p->mnt_child); |
7c4b93d8 AV |
1097 | if (p->mnt_parent != p) { |
1098 | p->mnt_parent->mnt_ghosts++; | |
5f57cbcc | 1099 | dentry_reset_mounted(p->mnt_parent, p->mnt_mountpoint); |
7c4b93d8 | 1100 | } |
a05964f3 | 1101 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
1102 | } |
1103 | } | |
1104 | ||
c35038be AV |
1105 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); |
1106 | ||
1da177e4 LT |
1107 | static int do_umount(struct vfsmount *mnt, int flags) |
1108 | { | |
b58fed8b | 1109 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 1110 | int retval; |
70fbcdf4 | 1111 | LIST_HEAD(umount_list); |
1da177e4 LT |
1112 | |
1113 | retval = security_sb_umount(mnt, flags); | |
1114 | if (retval) | |
1115 | return retval; | |
1116 | ||
1117 | /* | |
1118 | * Allow userspace to request a mountpoint be expired rather than | |
1119 | * unmounting unconditionally. Unmount only happens if: | |
1120 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1121 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1122 | */ | |
1123 | if (flags & MNT_EXPIRE) { | |
6ac08c39 | 1124 | if (mnt == current->fs->root.mnt || |
1da177e4 LT |
1125 | flags & (MNT_FORCE | MNT_DETACH)) |
1126 | return -EINVAL; | |
1127 | ||
1128 | if (atomic_read(&mnt->mnt_count) != 2) | |
1129 | return -EBUSY; | |
1130 | ||
1131 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
1132 | return -EAGAIN; | |
1133 | } | |
1134 | ||
1135 | /* | |
1136 | * If we may have to abort operations to get out of this | |
1137 | * mount, and they will themselves hold resources we must | |
1138 | * allow the fs to do things. In the Unix tradition of | |
1139 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1140 | * might fail to complete on the first run through as other tasks | |
1141 | * must return, and the like. Thats for the mount program to worry | |
1142 | * about for the moment. | |
1143 | */ | |
1144 | ||
42faad99 | 1145 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1146 | sb->s_op->umount_begin(sb); |
42faad99 | 1147 | } |
1da177e4 LT |
1148 | |
1149 | /* | |
1150 | * No sense to grab the lock for this test, but test itself looks | |
1151 | * somewhat bogus. Suggestions for better replacement? | |
1152 | * Ho-hum... In principle, we might treat that as umount + switch | |
1153 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1154 | * Actually it makes sense, especially if rootfs would contain a | |
1155 | * /reboot - static binary that would close all descriptors and | |
1156 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1157 | */ | |
6ac08c39 | 1158 | if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1159 | /* |
1160 | * Special case for "unmounting" root ... | |
1161 | * we just try to remount it readonly. | |
1162 | */ | |
1163 | down_write(&sb->s_umount); | |
4aa98cf7 | 1164 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1165 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1166 | up_write(&sb->s_umount); |
1167 | return retval; | |
1168 | } | |
1169 | ||
390c6843 | 1170 | down_write(&namespace_sem); |
99b7db7b | 1171 | br_write_lock(vfsmount_lock); |
5addc5dd | 1172 | event++; |
1da177e4 | 1173 | |
c35038be AV |
1174 | if (!(flags & MNT_DETACH)) |
1175 | shrink_submounts(mnt, &umount_list); | |
1176 | ||
1da177e4 | 1177 | retval = -EBUSY; |
a05964f3 | 1178 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1da177e4 | 1179 | if (!list_empty(&mnt->mnt_list)) |
a05964f3 | 1180 | umount_tree(mnt, 1, &umount_list); |
1da177e4 LT |
1181 | retval = 0; |
1182 | } | |
99b7db7b | 1183 | br_write_unlock(vfsmount_lock); |
390c6843 | 1184 | up_write(&namespace_sem); |
70fbcdf4 | 1185 | release_mounts(&umount_list); |
1da177e4 LT |
1186 | return retval; |
1187 | } | |
1188 | ||
1189 | /* | |
1190 | * Now umount can handle mount points as well as block devices. | |
1191 | * This is important for filesystems which use unnamed block devices. | |
1192 | * | |
1193 | * We now support a flag for forced unmount like the other 'big iron' | |
1194 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1195 | */ | |
1196 | ||
bdc480e3 | 1197 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1198 | { |
2d8f3038 | 1199 | struct path path; |
1da177e4 | 1200 | int retval; |
db1f05bb | 1201 | int lookup_flags = 0; |
1da177e4 | 1202 | |
db1f05bb MS |
1203 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
1204 | return -EINVAL; | |
1205 | ||
1206 | if (!(flags & UMOUNT_NOFOLLOW)) | |
1207 | lookup_flags |= LOOKUP_FOLLOW; | |
1208 | ||
1209 | retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); | |
1da177e4 LT |
1210 | if (retval) |
1211 | goto out; | |
1212 | retval = -EINVAL; | |
2d8f3038 | 1213 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1214 | goto dput_and_out; |
2d8f3038 | 1215 | if (!check_mnt(path.mnt)) |
1da177e4 LT |
1216 | goto dput_and_out; |
1217 | ||
1218 | retval = -EPERM; | |
1219 | if (!capable(CAP_SYS_ADMIN)) | |
1220 | goto dput_and_out; | |
1221 | ||
2d8f3038 | 1222 | retval = do_umount(path.mnt, flags); |
1da177e4 | 1223 | dput_and_out: |
429731b1 | 1224 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 AV |
1225 | dput(path.dentry); |
1226 | mntput_no_expire(path.mnt); | |
1da177e4 LT |
1227 | out: |
1228 | return retval; | |
1229 | } | |
1230 | ||
1231 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1232 | ||
1233 | /* | |
b58fed8b | 1234 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1235 | */ |
bdc480e3 | 1236 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1237 | { |
b58fed8b | 1238 | return sys_umount(name, 0); |
1da177e4 LT |
1239 | } |
1240 | ||
1241 | #endif | |
1242 | ||
2d92ab3c | 1243 | static int mount_is_safe(struct path *path) |
1da177e4 LT |
1244 | { |
1245 | if (capable(CAP_SYS_ADMIN)) | |
1246 | return 0; | |
1247 | return -EPERM; | |
1248 | #ifdef notyet | |
2d92ab3c | 1249 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
1da177e4 | 1250 | return -EPERM; |
2d92ab3c | 1251 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
da9592ed | 1252 | if (current_uid() != path->dentry->d_inode->i_uid) |
1da177e4 LT |
1253 | return -EPERM; |
1254 | } | |
2d92ab3c | 1255 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
1da177e4 LT |
1256 | return -EPERM; |
1257 | return 0; | |
1258 | #endif | |
1259 | } | |
1260 | ||
b90fa9ae | 1261 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
36341f64 | 1262 | int flag) |
1da177e4 LT |
1263 | { |
1264 | struct vfsmount *res, *p, *q, *r, *s; | |
1a390689 | 1265 | struct path path; |
1da177e4 | 1266 | |
9676f0c6 RP |
1267 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
1268 | return NULL; | |
1269 | ||
36341f64 | 1270 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
1271 | if (!q) |
1272 | goto Enomem; | |
1273 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
1274 | ||
1275 | p = mnt; | |
fdadd65f | 1276 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
7ec02ef1 | 1277 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1278 | continue; |
1279 | ||
1280 | for (s = r; s; s = next_mnt(s, r)) { | |
9676f0c6 RP |
1281 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
1282 | s = skip_mnt_tree(s); | |
1283 | continue; | |
1284 | } | |
1da177e4 LT |
1285 | while (p != s->mnt_parent) { |
1286 | p = p->mnt_parent; | |
1287 | q = q->mnt_parent; | |
1288 | } | |
1289 | p = s; | |
1a390689 AV |
1290 | path.mnt = q; |
1291 | path.dentry = p->mnt_mountpoint; | |
36341f64 | 1292 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
1293 | if (!q) |
1294 | goto Enomem; | |
99b7db7b | 1295 | br_write_lock(vfsmount_lock); |
1da177e4 | 1296 | list_add_tail(&q->mnt_list, &res->mnt_list); |
1a390689 | 1297 | attach_mnt(q, &path); |
99b7db7b | 1298 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
1299 | } |
1300 | } | |
1301 | return res; | |
b58fed8b | 1302 | Enomem: |
1da177e4 | 1303 | if (res) { |
70fbcdf4 | 1304 | LIST_HEAD(umount_list); |
99b7db7b | 1305 | br_write_lock(vfsmount_lock); |
a05964f3 | 1306 | umount_tree(res, 0, &umount_list); |
99b7db7b | 1307 | br_write_unlock(vfsmount_lock); |
70fbcdf4 | 1308 | release_mounts(&umount_list); |
1da177e4 LT |
1309 | } |
1310 | return NULL; | |
1311 | } | |
1312 | ||
589ff870 | 1313 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 AV |
1314 | { |
1315 | struct vfsmount *tree; | |
1a60a280 | 1316 | down_write(&namespace_sem); |
589ff870 | 1317 | tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); |
1a60a280 | 1318 | up_write(&namespace_sem); |
8aec0809 AV |
1319 | return tree; |
1320 | } | |
1321 | ||
1322 | void drop_collected_mounts(struct vfsmount *mnt) | |
1323 | { | |
1324 | LIST_HEAD(umount_list); | |
1a60a280 | 1325 | down_write(&namespace_sem); |
99b7db7b | 1326 | br_write_lock(vfsmount_lock); |
8aec0809 | 1327 | umount_tree(mnt, 0, &umount_list); |
99b7db7b | 1328 | br_write_unlock(vfsmount_lock); |
1a60a280 | 1329 | up_write(&namespace_sem); |
8aec0809 AV |
1330 | release_mounts(&umount_list); |
1331 | } | |
1332 | ||
1f707137 AV |
1333 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1334 | struct vfsmount *root) | |
1335 | { | |
1336 | struct vfsmount *mnt; | |
1337 | int res = f(root, arg); | |
1338 | if (res) | |
1339 | return res; | |
1340 | list_for_each_entry(mnt, &root->mnt_list, mnt_list) { | |
1341 | res = f(mnt, arg); | |
1342 | if (res) | |
1343 | return res; | |
1344 | } | |
1345 | return 0; | |
1346 | } | |
1347 | ||
719f5d7f MS |
1348 | static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) |
1349 | { | |
1350 | struct vfsmount *p; | |
1351 | ||
1352 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { | |
1353 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) | |
1354 | mnt_release_group_id(p); | |
1355 | } | |
1356 | } | |
1357 | ||
1358 | static int invent_group_ids(struct vfsmount *mnt, bool recurse) | |
1359 | { | |
1360 | struct vfsmount *p; | |
1361 | ||
1362 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { | |
1363 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { | |
1364 | int err = mnt_alloc_group_id(p); | |
1365 | if (err) { | |
1366 | cleanup_group_ids(mnt, p); | |
1367 | return err; | |
1368 | } | |
1369 | } | |
1370 | } | |
1371 | ||
1372 | return 0; | |
1373 | } | |
1374 | ||
b90fa9ae RP |
1375 | /* |
1376 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1377 | * @nd : place the mount tree @source_mnt is attached |
1378 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1379 | * store the parent mount and mountpoint dentry. | |
1380 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1381 | * |
1382 | * NOTE: in the table below explains the semantics when a source mount | |
1383 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1384 | * --------------------------------------------------------------------------- |
1385 | * | BIND MOUNT OPERATION | | |
1386 | * |************************************************************************** | |
1387 | * | source-->| shared | private | slave | unbindable | | |
1388 | * | dest | | | | | | |
1389 | * | | | | | | | | |
1390 | * | v | | | | | | |
1391 | * |************************************************************************** | |
1392 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1393 | * | | | | | | | |
1394 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1395 | * *************************************************************************** | |
b90fa9ae RP |
1396 | * A bind operation clones the source mount and mounts the clone on the |
1397 | * destination mount. | |
1398 | * | |
1399 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1400 | * tree of the destination mount and the cloned mount is added to | |
1401 | * the peer group of the source mount. | |
1402 | * (+) the cloned mount is created under the destination mount and is marked | |
1403 | * as shared. The cloned mount is added to the peer group of the source | |
1404 | * mount. | |
5afe0022 RP |
1405 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1406 | * of the destination mount and the cloned mount is made slave | |
1407 | * of the same master as that of the source mount. The cloned mount | |
1408 | * is marked as 'shared and slave'. | |
1409 | * (*) the cloned mount is made a slave of the same master as that of the | |
1410 | * source mount. | |
1411 | * | |
9676f0c6 RP |
1412 | * --------------------------------------------------------------------------- |
1413 | * | MOVE MOUNT OPERATION | | |
1414 | * |************************************************************************** | |
1415 | * | source-->| shared | private | slave | unbindable | | |
1416 | * | dest | | | | | | |
1417 | * | | | | | | | | |
1418 | * | v | | | | | | |
1419 | * |************************************************************************** | |
1420 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1421 | * | | | | | | | |
1422 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1423 | * *************************************************************************** | |
5afe0022 RP |
1424 | * |
1425 | * (+) the mount is moved to the destination. And is then propagated to | |
1426 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1427 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1428 | * (+++) the mount is moved to the destination and is then propagated to |
1429 | * all the mounts belonging to the destination mount's propagation tree. | |
1430 | * the mount is marked as 'shared and slave'. | |
1431 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1432 | * |
1433 | * if the source mount is a tree, the operations explained above is | |
1434 | * applied to each mount in the tree. | |
1435 | * Must be called without spinlocks held, since this function can sleep | |
1436 | * in allocations. | |
1437 | */ | |
1438 | static int attach_recursive_mnt(struct vfsmount *source_mnt, | |
1a390689 | 1439 | struct path *path, struct path *parent_path) |
b90fa9ae RP |
1440 | { |
1441 | LIST_HEAD(tree_list); | |
1a390689 AV |
1442 | struct vfsmount *dest_mnt = path->mnt; |
1443 | struct dentry *dest_dentry = path->dentry; | |
b90fa9ae | 1444 | struct vfsmount *child, *p; |
719f5d7f | 1445 | int err; |
b90fa9ae | 1446 | |
719f5d7f MS |
1447 | if (IS_MNT_SHARED(dest_mnt)) { |
1448 | err = invent_group_ids(source_mnt, true); | |
1449 | if (err) | |
1450 | goto out; | |
1451 | } | |
1452 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); | |
1453 | if (err) | |
1454 | goto out_cleanup_ids; | |
b90fa9ae | 1455 | |
99b7db7b | 1456 | br_write_lock(vfsmount_lock); |
df1a1ad2 | 1457 | |
b90fa9ae RP |
1458 | if (IS_MNT_SHARED(dest_mnt)) { |
1459 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) | |
1460 | set_mnt_shared(p); | |
1461 | } | |
1a390689 AV |
1462 | if (parent_path) { |
1463 | detach_mnt(source_mnt, parent_path); | |
1464 | attach_mnt(source_mnt, path); | |
e5d67f07 | 1465 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
21444403 RP |
1466 | } else { |
1467 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); | |
1468 | commit_tree(source_mnt); | |
1469 | } | |
b90fa9ae RP |
1470 | |
1471 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { | |
1472 | list_del_init(&child->mnt_hash); | |
1473 | commit_tree(child); | |
1474 | } | |
99b7db7b NP |
1475 | br_write_unlock(vfsmount_lock); |
1476 | ||
b90fa9ae | 1477 | return 0; |
719f5d7f MS |
1478 | |
1479 | out_cleanup_ids: | |
1480 | if (IS_MNT_SHARED(dest_mnt)) | |
1481 | cleanup_group_ids(source_mnt, NULL); | |
1482 | out: | |
1483 | return err; | |
b90fa9ae RP |
1484 | } |
1485 | ||
8c3ee42e | 1486 | static int graft_tree(struct vfsmount *mnt, struct path *path) |
1da177e4 LT |
1487 | { |
1488 | int err; | |
1489 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
1490 | return -EINVAL; | |
1491 | ||
8c3ee42e | 1492 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1da177e4 LT |
1493 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
1494 | return -ENOTDIR; | |
1495 | ||
1496 | err = -ENOENT; | |
8c3ee42e | 1497 | mutex_lock(&path->dentry->d_inode->i_mutex); |
d83c49f3 | 1498 | if (cant_mount(path->dentry)) |
1da177e4 LT |
1499 | goto out_unlock; |
1500 | ||
f3da392e | 1501 | if (!d_unlinked(path->dentry)) |
8c3ee42e | 1502 | err = attach_recursive_mnt(mnt, path, NULL); |
1da177e4 | 1503 | out_unlock: |
8c3ee42e | 1504 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 LT |
1505 | return err; |
1506 | } | |
1507 | ||
7a2e8a8f VA |
1508 | /* |
1509 | * Sanity check the flags to change_mnt_propagation. | |
1510 | */ | |
1511 | ||
1512 | static int flags_to_propagation_type(int flags) | |
1513 | { | |
1514 | int type = flags & ~MS_REC; | |
1515 | ||
1516 | /* Fail if any non-propagation flags are set */ | |
1517 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
1518 | return 0; | |
1519 | /* Only one propagation flag should be set */ | |
1520 | if (!is_power_of_2(type)) | |
1521 | return 0; | |
1522 | return type; | |
1523 | } | |
1524 | ||
07b20889 RP |
1525 | /* |
1526 | * recursively change the type of the mountpoint. | |
1527 | */ | |
0a0d8a46 | 1528 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1529 | { |
2d92ab3c | 1530 | struct vfsmount *m, *mnt = path->mnt; |
07b20889 | 1531 | int recurse = flag & MS_REC; |
7a2e8a8f | 1532 | int type; |
719f5d7f | 1533 | int err = 0; |
07b20889 | 1534 | |
ee6f9582 MS |
1535 | if (!capable(CAP_SYS_ADMIN)) |
1536 | return -EPERM; | |
1537 | ||
2d92ab3c | 1538 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
1539 | return -EINVAL; |
1540 | ||
7a2e8a8f VA |
1541 | type = flags_to_propagation_type(flag); |
1542 | if (!type) | |
1543 | return -EINVAL; | |
1544 | ||
07b20889 | 1545 | down_write(&namespace_sem); |
719f5d7f MS |
1546 | if (type == MS_SHARED) { |
1547 | err = invent_group_ids(mnt, recurse); | |
1548 | if (err) | |
1549 | goto out_unlock; | |
1550 | } | |
1551 | ||
99b7db7b | 1552 | br_write_lock(vfsmount_lock); |
07b20889 RP |
1553 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
1554 | change_mnt_propagation(m, type); | |
99b7db7b | 1555 | br_write_unlock(vfsmount_lock); |
719f5d7f MS |
1556 | |
1557 | out_unlock: | |
07b20889 | 1558 | up_write(&namespace_sem); |
719f5d7f | 1559 | return err; |
07b20889 RP |
1560 | } |
1561 | ||
1da177e4 LT |
1562 | /* |
1563 | * do loopback mount. | |
1564 | */ | |
0a0d8a46 | 1565 | static int do_loopback(struct path *path, char *old_name, |
2dafe1c4 | 1566 | int recurse) |
1da177e4 | 1567 | { |
2d92ab3c | 1568 | struct path old_path; |
1da177e4 | 1569 | struct vfsmount *mnt = NULL; |
2d92ab3c | 1570 | int err = mount_is_safe(path); |
1da177e4 LT |
1571 | if (err) |
1572 | return err; | |
1573 | if (!old_name || !*old_name) | |
1574 | return -EINVAL; | |
2d92ab3c | 1575 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1576 | if (err) |
1577 | return err; | |
1578 | ||
390c6843 | 1579 | down_write(&namespace_sem); |
1da177e4 | 1580 | err = -EINVAL; |
2d92ab3c | 1581 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
4ac91378 | 1582 | goto out; |
9676f0c6 | 1583 | |
2d92ab3c | 1584 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
ccd48bc7 | 1585 | goto out; |
1da177e4 | 1586 | |
ccd48bc7 AV |
1587 | err = -ENOMEM; |
1588 | if (recurse) | |
2d92ab3c | 1589 | mnt = copy_tree(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 | 1590 | else |
2d92ab3c | 1591 | mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 AV |
1592 | |
1593 | if (!mnt) | |
1594 | goto out; | |
1595 | ||
2d92ab3c | 1596 | err = graft_tree(mnt, path); |
ccd48bc7 | 1597 | if (err) { |
70fbcdf4 | 1598 | LIST_HEAD(umount_list); |
99b7db7b NP |
1599 | |
1600 | br_write_lock(vfsmount_lock); | |
a05964f3 | 1601 | umount_tree(mnt, 0, &umount_list); |
99b7db7b | 1602 | br_write_unlock(vfsmount_lock); |
70fbcdf4 | 1603 | release_mounts(&umount_list); |
5b83d2c5 | 1604 | } |
1da177e4 | 1605 | |
ccd48bc7 | 1606 | out: |
390c6843 | 1607 | up_write(&namespace_sem); |
2d92ab3c | 1608 | path_put(&old_path); |
1da177e4 LT |
1609 | return err; |
1610 | } | |
1611 | ||
2e4b7fcd DH |
1612 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
1613 | { | |
1614 | int error = 0; | |
1615 | int readonly_request = 0; | |
1616 | ||
1617 | if (ms_flags & MS_RDONLY) | |
1618 | readonly_request = 1; | |
1619 | if (readonly_request == __mnt_is_readonly(mnt)) | |
1620 | return 0; | |
1621 | ||
1622 | if (readonly_request) | |
1623 | error = mnt_make_readonly(mnt); | |
1624 | else | |
1625 | __mnt_unmake_readonly(mnt); | |
1626 | return error; | |
1627 | } | |
1628 | ||
1da177e4 LT |
1629 | /* |
1630 | * change filesystem flags. dir should be a physical root of filesystem. | |
1631 | * If you've mounted a non-root directory somewhere and want to do remount | |
1632 | * on it - tough luck. | |
1633 | */ | |
0a0d8a46 | 1634 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
1635 | void *data) |
1636 | { | |
1637 | int err; | |
2d92ab3c | 1638 | struct super_block *sb = path->mnt->mnt_sb; |
1da177e4 LT |
1639 | |
1640 | if (!capable(CAP_SYS_ADMIN)) | |
1641 | return -EPERM; | |
1642 | ||
2d92ab3c | 1643 | if (!check_mnt(path->mnt)) |
1da177e4 LT |
1644 | return -EINVAL; |
1645 | ||
2d92ab3c | 1646 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
1647 | return -EINVAL; |
1648 | ||
1649 | down_write(&sb->s_umount); | |
2e4b7fcd | 1650 | if (flags & MS_BIND) |
2d92ab3c | 1651 | err = change_mount_flags(path->mnt, flags); |
4aa98cf7 | 1652 | else |
2e4b7fcd | 1653 | err = do_remount_sb(sb, flags, data, 0); |
7b43a79f | 1654 | if (!err) { |
99b7db7b | 1655 | br_write_lock(vfsmount_lock); |
495d6c9c | 1656 | mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK; |
2d92ab3c | 1657 | path->mnt->mnt_flags = mnt_flags; |
99b7db7b | 1658 | br_write_unlock(vfsmount_lock); |
7b43a79f | 1659 | } |
1da177e4 | 1660 | up_write(&sb->s_umount); |
0e55a7cc | 1661 | if (!err) { |
99b7db7b | 1662 | br_write_lock(vfsmount_lock); |
0e55a7cc | 1663 | touch_mnt_namespace(path->mnt->mnt_ns); |
99b7db7b | 1664 | br_write_unlock(vfsmount_lock); |
0e55a7cc | 1665 | } |
1da177e4 LT |
1666 | return err; |
1667 | } | |
1668 | ||
9676f0c6 RP |
1669 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
1670 | { | |
1671 | struct vfsmount *p; | |
1672 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
1673 | if (IS_MNT_UNBINDABLE(p)) | |
1674 | return 1; | |
1675 | } | |
1676 | return 0; | |
1677 | } | |
1678 | ||
0a0d8a46 | 1679 | static int do_move_mount(struct path *path, char *old_name) |
1da177e4 | 1680 | { |
2d92ab3c | 1681 | struct path old_path, parent_path; |
1da177e4 LT |
1682 | struct vfsmount *p; |
1683 | int err = 0; | |
1684 | if (!capable(CAP_SYS_ADMIN)) | |
1685 | return -EPERM; | |
1686 | if (!old_name || !*old_name) | |
1687 | return -EINVAL; | |
2d92ab3c | 1688 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1689 | if (err) |
1690 | return err; | |
1691 | ||
390c6843 | 1692 | down_write(&namespace_sem); |
2d92ab3c | 1693 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1694 | follow_down(path)) |
1da177e4 LT |
1695 | ; |
1696 | err = -EINVAL; | |
2d92ab3c | 1697 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
1da177e4 LT |
1698 | goto out; |
1699 | ||
1700 | err = -ENOENT; | |
2d92ab3c | 1701 | mutex_lock(&path->dentry->d_inode->i_mutex); |
d83c49f3 | 1702 | if (cant_mount(path->dentry)) |
1da177e4 LT |
1703 | goto out1; |
1704 | ||
f3da392e | 1705 | if (d_unlinked(path->dentry)) |
21444403 | 1706 | goto out1; |
1da177e4 LT |
1707 | |
1708 | err = -EINVAL; | |
2d92ab3c | 1709 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 1710 | goto out1; |
1da177e4 | 1711 | |
2d92ab3c | 1712 | if (old_path.mnt == old_path.mnt->mnt_parent) |
21444403 | 1713 | goto out1; |
1da177e4 | 1714 | |
2d92ab3c AV |
1715 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1716 | S_ISDIR(old_path.dentry->d_inode->i_mode)) | |
21444403 RP |
1717 | goto out1; |
1718 | /* | |
1719 | * Don't move a mount residing in a shared parent. | |
1720 | */ | |
2d92ab3c AV |
1721 | if (old_path.mnt->mnt_parent && |
1722 | IS_MNT_SHARED(old_path.mnt->mnt_parent)) | |
21444403 | 1723 | goto out1; |
9676f0c6 RP |
1724 | /* |
1725 | * Don't move a mount tree containing unbindable mounts to a destination | |
1726 | * mount which is shared. | |
1727 | */ | |
2d92ab3c AV |
1728 | if (IS_MNT_SHARED(path->mnt) && |
1729 | tree_contains_unbindable(old_path.mnt)) | |
9676f0c6 | 1730 | goto out1; |
1da177e4 | 1731 | err = -ELOOP; |
2d92ab3c AV |
1732 | for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1733 | if (p == old_path.mnt) | |
21444403 | 1734 | goto out1; |
1da177e4 | 1735 | |
2d92ab3c | 1736 | err = attach_recursive_mnt(old_path.mnt, path, &parent_path); |
4ac91378 | 1737 | if (err) |
21444403 | 1738 | goto out1; |
1da177e4 LT |
1739 | |
1740 | /* if the mount is moved, it should no longer be expire | |
1741 | * automatically */ | |
2d92ab3c | 1742 | list_del_init(&old_path.mnt->mnt_expire); |
1da177e4 | 1743 | out1: |
2d92ab3c | 1744 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 | 1745 | out: |
390c6843 | 1746 | up_write(&namespace_sem); |
1da177e4 | 1747 | if (!err) |
1a390689 | 1748 | path_put(&parent_path); |
2d92ab3c | 1749 | path_put(&old_path); |
1da177e4 LT |
1750 | return err; |
1751 | } | |
1752 | ||
1753 | /* | |
1754 | * create a new mount for userspace and request it to be added into the | |
1755 | * namespace's tree | |
1756 | */ | |
0a0d8a46 | 1757 | static int do_new_mount(struct path *path, char *type, int flags, |
1da177e4 LT |
1758 | int mnt_flags, char *name, void *data) |
1759 | { | |
1760 | struct vfsmount *mnt; | |
1761 | ||
eca6f534 | 1762 | if (!type) |
1da177e4 LT |
1763 | return -EINVAL; |
1764 | ||
1765 | /* we need capabilities... */ | |
1766 | if (!capable(CAP_SYS_ADMIN)) | |
1767 | return -EPERM; | |
1768 | ||
1769 | mnt = do_kern_mount(type, flags, name, data); | |
1770 | if (IS_ERR(mnt)) | |
1771 | return PTR_ERR(mnt); | |
1772 | ||
2d92ab3c | 1773 | return do_add_mount(mnt, path, mnt_flags, NULL); |
1da177e4 LT |
1774 | } |
1775 | ||
1776 | /* | |
1777 | * add a mount into a namespace's mount tree | |
1778 | * - provide the option of adding the new mount to an expiration list | |
1779 | */ | |
8d66bf54 | 1780 | int do_add_mount(struct vfsmount *newmnt, struct path *path, |
1da177e4 LT |
1781 | int mnt_flags, struct list_head *fslist) |
1782 | { | |
1783 | int err; | |
1784 | ||
8089352a | 1785 | mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); |
27d55f1f | 1786 | |
390c6843 | 1787 | down_write(&namespace_sem); |
1da177e4 | 1788 | /* Something was mounted here while we slept */ |
8d66bf54 | 1789 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1790 | follow_down(path)) |
1da177e4 LT |
1791 | ; |
1792 | err = -EINVAL; | |
dd5cae6e | 1793 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) |
1da177e4 LT |
1794 | goto unlock; |
1795 | ||
1796 | /* Refuse the same filesystem on the same mount point */ | |
1797 | err = -EBUSY; | |
8d66bf54 AV |
1798 | if (path->mnt->mnt_sb == newmnt->mnt_sb && |
1799 | path->mnt->mnt_root == path->dentry) | |
1da177e4 LT |
1800 | goto unlock; |
1801 | ||
1802 | err = -EINVAL; | |
1803 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
1804 | goto unlock; | |
1805 | ||
1806 | newmnt->mnt_flags = mnt_flags; | |
8d66bf54 | 1807 | if ((err = graft_tree(newmnt, path))) |
5b83d2c5 | 1808 | goto unlock; |
1da177e4 | 1809 | |
6758f953 | 1810 | if (fslist) /* add to the specified expiration list */ |
55e700b9 | 1811 | list_add_tail(&newmnt->mnt_expire, fslist); |
6758f953 | 1812 | |
390c6843 | 1813 | up_write(&namespace_sem); |
5b83d2c5 | 1814 | return 0; |
1da177e4 LT |
1815 | |
1816 | unlock: | |
390c6843 | 1817 | up_write(&namespace_sem); |
1da177e4 LT |
1818 | mntput(newmnt); |
1819 | return err; | |
1820 | } | |
1821 | ||
1822 | EXPORT_SYMBOL_GPL(do_add_mount); | |
1823 | ||
1824 | /* | |
1825 | * process a list of expirable mountpoints with the intent of discarding any | |
1826 | * mountpoints that aren't in use and haven't been touched since last we came | |
1827 | * here | |
1828 | */ | |
1829 | void mark_mounts_for_expiry(struct list_head *mounts) | |
1830 | { | |
1da177e4 LT |
1831 | struct vfsmount *mnt, *next; |
1832 | LIST_HEAD(graveyard); | |
bcc5c7d2 | 1833 | LIST_HEAD(umounts); |
1da177e4 LT |
1834 | |
1835 | if (list_empty(mounts)) | |
1836 | return; | |
1837 | ||
bcc5c7d2 | 1838 | down_write(&namespace_sem); |
99b7db7b | 1839 | br_write_lock(vfsmount_lock); |
1da177e4 LT |
1840 | |
1841 | /* extract from the expiration list every vfsmount that matches the | |
1842 | * following criteria: | |
1843 | * - only referenced by its parent vfsmount | |
1844 | * - still marked for expiry (marked on the last call here; marks are | |
1845 | * cleared by mntput()) | |
1846 | */ | |
55e700b9 | 1847 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 | 1848 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
bcc5c7d2 | 1849 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 1850 | continue; |
55e700b9 | 1851 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 1852 | } |
bcc5c7d2 AV |
1853 | while (!list_empty(&graveyard)) { |
1854 | mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); | |
1855 | touch_mnt_namespace(mnt->mnt_ns); | |
1856 | umount_tree(mnt, 1, &umounts); | |
1857 | } | |
99b7db7b | 1858 | br_write_unlock(vfsmount_lock); |
bcc5c7d2 AV |
1859 | up_write(&namespace_sem); |
1860 | ||
1861 | release_mounts(&umounts); | |
5528f911 TM |
1862 | } |
1863 | ||
1864 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
1865 | ||
1866 | /* | |
1867 | * Ripoff of 'select_parent()' | |
1868 | * | |
1869 | * search the list of submounts for a given mountpoint, and move any | |
1870 | * shrinkable submounts to the 'graveyard' list. | |
1871 | */ | |
1872 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) | |
1873 | { | |
1874 | struct vfsmount *this_parent = parent; | |
1875 | struct list_head *next; | |
1876 | int found = 0; | |
1877 | ||
1878 | repeat: | |
1879 | next = this_parent->mnt_mounts.next; | |
1880 | resume: | |
1881 | while (next != &this_parent->mnt_mounts) { | |
1882 | struct list_head *tmp = next; | |
1883 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); | |
1884 | ||
1885 | next = tmp->next; | |
1886 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) | |
1da177e4 | 1887 | continue; |
5528f911 TM |
1888 | /* |
1889 | * Descend a level if the d_mounts list is non-empty. | |
1890 | */ | |
1891 | if (!list_empty(&mnt->mnt_mounts)) { | |
1892 | this_parent = mnt; | |
1893 | goto repeat; | |
1894 | } | |
1da177e4 | 1895 | |
5528f911 | 1896 | if (!propagate_mount_busy(mnt, 1)) { |
5528f911 TM |
1897 | list_move_tail(&mnt->mnt_expire, graveyard); |
1898 | found++; | |
1899 | } | |
1da177e4 | 1900 | } |
5528f911 TM |
1901 | /* |
1902 | * All done at this level ... ascend and resume the search | |
1903 | */ | |
1904 | if (this_parent != parent) { | |
1905 | next = this_parent->mnt_child.next; | |
1906 | this_parent = this_parent->mnt_parent; | |
1907 | goto resume; | |
1908 | } | |
1909 | return found; | |
1910 | } | |
1911 | ||
1912 | /* | |
1913 | * process a list of expirable mountpoints with the intent of discarding any | |
1914 | * submounts of a specific parent mountpoint | |
99b7db7b NP |
1915 | * |
1916 | * vfsmount_lock must be held for write | |
5528f911 | 1917 | */ |
c35038be | 1918 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) |
5528f911 TM |
1919 | { |
1920 | LIST_HEAD(graveyard); | |
c35038be | 1921 | struct vfsmount *m; |
5528f911 | 1922 | |
5528f911 | 1923 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 1924 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 1925 | while (!list_empty(&graveyard)) { |
c35038be | 1926 | m = list_first_entry(&graveyard, struct vfsmount, |
bcc5c7d2 | 1927 | mnt_expire); |
afef80b3 EB |
1928 | touch_mnt_namespace(m->mnt_ns); |
1929 | umount_tree(m, 1, umounts); | |
bcc5c7d2 AV |
1930 | } |
1931 | } | |
1da177e4 LT |
1932 | } |
1933 | ||
1da177e4 LT |
1934 | /* |
1935 | * Some copy_from_user() implementations do not return the exact number of | |
1936 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
1937 | * Note that this function differs from copy_from_user() in that it will oops | |
1938 | * on bad values of `to', rather than returning a short copy. | |
1939 | */ | |
b58fed8b RP |
1940 | static long exact_copy_from_user(void *to, const void __user * from, |
1941 | unsigned long n) | |
1da177e4 LT |
1942 | { |
1943 | char *t = to; | |
1944 | const char __user *f = from; | |
1945 | char c; | |
1946 | ||
1947 | if (!access_ok(VERIFY_READ, from, n)) | |
1948 | return n; | |
1949 | ||
1950 | while (n) { | |
1951 | if (__get_user(c, f)) { | |
1952 | memset(t, 0, n); | |
1953 | break; | |
1954 | } | |
1955 | *t++ = c; | |
1956 | f++; | |
1957 | n--; | |
1958 | } | |
1959 | return n; | |
1960 | } | |
1961 | ||
b58fed8b | 1962 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
1963 | { |
1964 | int i; | |
1965 | unsigned long page; | |
1966 | unsigned long size; | |
b58fed8b | 1967 | |
1da177e4 LT |
1968 | *where = 0; |
1969 | if (!data) | |
1970 | return 0; | |
1971 | ||
1972 | if (!(page = __get_free_page(GFP_KERNEL))) | |
1973 | return -ENOMEM; | |
1974 | ||
1975 | /* We only care that *some* data at the address the user | |
1976 | * gave us is valid. Just in case, we'll zero | |
1977 | * the remainder of the page. | |
1978 | */ | |
1979 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
1980 | size = TASK_SIZE - (unsigned long)data; | |
1981 | if (size > PAGE_SIZE) | |
1982 | size = PAGE_SIZE; | |
1983 | ||
1984 | i = size - exact_copy_from_user((void *)page, data, size); | |
1985 | if (!i) { | |
b58fed8b | 1986 | free_page(page); |
1da177e4 LT |
1987 | return -EFAULT; |
1988 | } | |
1989 | if (i != PAGE_SIZE) | |
1990 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
1991 | *where = page; | |
1992 | return 0; | |
1993 | } | |
1994 | ||
eca6f534 VN |
1995 | int copy_mount_string(const void __user *data, char **where) |
1996 | { | |
1997 | char *tmp; | |
1998 | ||
1999 | if (!data) { | |
2000 | *where = NULL; | |
2001 | return 0; | |
2002 | } | |
2003 | ||
2004 | tmp = strndup_user(data, PAGE_SIZE); | |
2005 | if (IS_ERR(tmp)) | |
2006 | return PTR_ERR(tmp); | |
2007 | ||
2008 | *where = tmp; | |
2009 | return 0; | |
2010 | } | |
2011 | ||
1da177e4 LT |
2012 | /* |
2013 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
2014 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
2015 | * | |
2016 | * data is a (void *) that can point to any structure up to | |
2017 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
2018 | * information (or be NULL). | |
2019 | * | |
2020 | * Pre-0.97 versions of mount() didn't have a flags word. | |
2021 | * When the flags word was introduced its top half was required | |
2022 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
2023 | * Therefore, if this magic number is present, it carries no information | |
2024 | * and must be discarded. | |
2025 | */ | |
b58fed8b | 2026 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
2027 | unsigned long flags, void *data_page) |
2028 | { | |
2d92ab3c | 2029 | struct path path; |
1da177e4 LT |
2030 | int retval = 0; |
2031 | int mnt_flags = 0; | |
2032 | ||
2033 | /* Discard magic */ | |
2034 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
2035 | flags &= ~MS_MGC_MSK; | |
2036 | ||
2037 | /* Basic sanity checks */ | |
2038 | ||
2039 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
2040 | return -EINVAL; | |
1da177e4 LT |
2041 | |
2042 | if (data_page) | |
2043 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
2044 | ||
a27ab9f2 TH |
2045 | /* ... and get the mountpoint */ |
2046 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); | |
2047 | if (retval) | |
2048 | return retval; | |
2049 | ||
2050 | retval = security_sb_mount(dev_name, &path, | |
2051 | type_page, flags, data_page); | |
2052 | if (retval) | |
2053 | goto dput_out; | |
2054 | ||
613cbe3d AK |
2055 | /* Default to relatime unless overriden */ |
2056 | if (!(flags & MS_NOATIME)) | |
2057 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 2058 | |
1da177e4 LT |
2059 | /* Separate the per-mountpoint flags */ |
2060 | if (flags & MS_NOSUID) | |
2061 | mnt_flags |= MNT_NOSUID; | |
2062 | if (flags & MS_NODEV) | |
2063 | mnt_flags |= MNT_NODEV; | |
2064 | if (flags & MS_NOEXEC) | |
2065 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
2066 | if (flags & MS_NOATIME) |
2067 | mnt_flags |= MNT_NOATIME; | |
2068 | if (flags & MS_NODIRATIME) | |
2069 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
2070 | if (flags & MS_STRICTATIME) |
2071 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
2072 | if (flags & MS_RDONLY) |
2073 | mnt_flags |= MNT_READONLY; | |
fc33a7bb | 2074 | |
7a4dec53 | 2075 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
d0adde57 MG |
2076 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
2077 | MS_STRICTATIME); | |
1da177e4 | 2078 | |
1da177e4 | 2079 | if (flags & MS_REMOUNT) |
2d92ab3c | 2080 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
2081 | data_page); |
2082 | else if (flags & MS_BIND) | |
2d92ab3c | 2083 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 2084 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 2085 | retval = do_change_type(&path, flags); |
1da177e4 | 2086 | else if (flags & MS_MOVE) |
2d92ab3c | 2087 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 2088 | else |
2d92ab3c | 2089 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
2090 | dev_name, data_page); |
2091 | dput_out: | |
2d92ab3c | 2092 | path_put(&path); |
1da177e4 LT |
2093 | return retval; |
2094 | } | |
2095 | ||
cf8d2c11 TM |
2096 | static struct mnt_namespace *alloc_mnt_ns(void) |
2097 | { | |
2098 | struct mnt_namespace *new_ns; | |
2099 | ||
2100 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
2101 | if (!new_ns) | |
2102 | return ERR_PTR(-ENOMEM); | |
2103 | atomic_set(&new_ns->count, 1); | |
2104 | new_ns->root = NULL; | |
2105 | INIT_LIST_HEAD(&new_ns->list); | |
2106 | init_waitqueue_head(&new_ns->poll); | |
2107 | new_ns->event = 0; | |
2108 | return new_ns; | |
2109 | } | |
2110 | ||
741a2951 JD |
2111 | /* |
2112 | * Allocate a new namespace structure and populate it with contents | |
2113 | * copied from the namespace of the passed in task structure. | |
2114 | */ | |
e3222c4e | 2115 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
6b3286ed | 2116 | struct fs_struct *fs) |
1da177e4 | 2117 | { |
6b3286ed | 2118 | struct mnt_namespace *new_ns; |
7f2da1e7 | 2119 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
1da177e4 LT |
2120 | struct vfsmount *p, *q; |
2121 | ||
cf8d2c11 TM |
2122 | new_ns = alloc_mnt_ns(); |
2123 | if (IS_ERR(new_ns)) | |
2124 | return new_ns; | |
1da177e4 | 2125 | |
390c6843 | 2126 | down_write(&namespace_sem); |
1da177e4 | 2127 | /* First pass: copy the tree topology */ |
6b3286ed | 2128 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
9676f0c6 | 2129 | CL_COPY_ALL | CL_EXPIRE); |
1da177e4 | 2130 | if (!new_ns->root) { |
390c6843 | 2131 | up_write(&namespace_sem); |
1da177e4 | 2132 | kfree(new_ns); |
5cc4a034 | 2133 | return ERR_PTR(-ENOMEM); |
1da177e4 | 2134 | } |
99b7db7b | 2135 | br_write_lock(vfsmount_lock); |
1da177e4 | 2136 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
99b7db7b | 2137 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
2138 | |
2139 | /* | |
2140 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2141 | * as belonging to new namespace. We have already acquired a private | |
2142 | * fs_struct, so tsk->fs->lock is not needed. | |
2143 | */ | |
6b3286ed | 2144 | p = mnt_ns->root; |
1da177e4 LT |
2145 | q = new_ns->root; |
2146 | while (p) { | |
6b3286ed | 2147 | q->mnt_ns = new_ns; |
1da177e4 | 2148 | if (fs) { |
6ac08c39 | 2149 | if (p == fs->root.mnt) { |
1da177e4 | 2150 | rootmnt = p; |
6ac08c39 | 2151 | fs->root.mnt = mntget(q); |
1da177e4 | 2152 | } |
6ac08c39 | 2153 | if (p == fs->pwd.mnt) { |
1da177e4 | 2154 | pwdmnt = p; |
6ac08c39 | 2155 | fs->pwd.mnt = mntget(q); |
1da177e4 | 2156 | } |
1da177e4 | 2157 | } |
6b3286ed | 2158 | p = next_mnt(p, mnt_ns->root); |
1da177e4 LT |
2159 | q = next_mnt(q, new_ns->root); |
2160 | } | |
390c6843 | 2161 | up_write(&namespace_sem); |
1da177e4 | 2162 | |
1da177e4 LT |
2163 | if (rootmnt) |
2164 | mntput(rootmnt); | |
2165 | if (pwdmnt) | |
2166 | mntput(pwdmnt); | |
1da177e4 | 2167 | |
741a2951 JD |
2168 | return new_ns; |
2169 | } | |
2170 | ||
213dd266 | 2171 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
e3222c4e | 2172 | struct fs_struct *new_fs) |
741a2951 | 2173 | { |
6b3286ed | 2174 | struct mnt_namespace *new_ns; |
741a2951 | 2175 | |
e3222c4e | 2176 | BUG_ON(!ns); |
6b3286ed | 2177 | get_mnt_ns(ns); |
741a2951 JD |
2178 | |
2179 | if (!(flags & CLONE_NEWNS)) | |
e3222c4e | 2180 | return ns; |
741a2951 | 2181 | |
e3222c4e | 2182 | new_ns = dup_mnt_ns(ns, new_fs); |
741a2951 | 2183 | |
6b3286ed | 2184 | put_mnt_ns(ns); |
e3222c4e | 2185 | return new_ns; |
1da177e4 LT |
2186 | } |
2187 | ||
cf8d2c11 TM |
2188 | /** |
2189 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2190 | * @mnt: pointer to the new root filesystem mountpoint | |
2191 | */ | |
a2770d86 | 2192 | struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt) |
cf8d2c11 TM |
2193 | { |
2194 | struct mnt_namespace *new_ns; | |
2195 | ||
2196 | new_ns = alloc_mnt_ns(); | |
2197 | if (!IS_ERR(new_ns)) { | |
2198 | mnt->mnt_ns = new_ns; | |
2199 | new_ns->root = mnt; | |
2200 | list_add(&new_ns->list, &new_ns->root->mnt_list); | |
2201 | } | |
2202 | return new_ns; | |
2203 | } | |
a2770d86 | 2204 | EXPORT_SYMBOL(create_mnt_ns); |
cf8d2c11 | 2205 | |
bdc480e3 HC |
2206 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2207 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2208 | { |
eca6f534 VN |
2209 | int ret; |
2210 | char *kernel_type; | |
2211 | char *kernel_dir; | |
2212 | char *kernel_dev; | |
1da177e4 | 2213 | unsigned long data_page; |
1da177e4 | 2214 | |
eca6f534 VN |
2215 | ret = copy_mount_string(type, &kernel_type); |
2216 | if (ret < 0) | |
2217 | goto out_type; | |
1da177e4 | 2218 | |
eca6f534 VN |
2219 | kernel_dir = getname(dir_name); |
2220 | if (IS_ERR(kernel_dir)) { | |
2221 | ret = PTR_ERR(kernel_dir); | |
2222 | goto out_dir; | |
2223 | } | |
1da177e4 | 2224 | |
eca6f534 VN |
2225 | ret = copy_mount_string(dev_name, &kernel_dev); |
2226 | if (ret < 0) | |
2227 | goto out_dev; | |
1da177e4 | 2228 | |
eca6f534 VN |
2229 | ret = copy_mount_options(data, &data_page); |
2230 | if (ret < 0) | |
2231 | goto out_data; | |
1da177e4 | 2232 | |
eca6f534 VN |
2233 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
2234 | (void *) data_page); | |
1da177e4 | 2235 | |
eca6f534 VN |
2236 | free_page(data_page); |
2237 | out_data: | |
2238 | kfree(kernel_dev); | |
2239 | out_dev: | |
2240 | putname(kernel_dir); | |
2241 | out_dir: | |
2242 | kfree(kernel_type); | |
2243 | out_type: | |
2244 | return ret; | |
1da177e4 LT |
2245 | } |
2246 | ||
1da177e4 LT |
2247 | /* |
2248 | * pivot_root Semantics: | |
2249 | * Moves the root file system of the current process to the directory put_old, | |
2250 | * makes new_root as the new root file system of the current process, and sets | |
2251 | * root/cwd of all processes which had them on the current root to new_root. | |
2252 | * | |
2253 | * Restrictions: | |
2254 | * The new_root and put_old must be directories, and must not be on the | |
2255 | * same file system as the current process root. The put_old must be | |
2256 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2257 | * pointed to by put_old must yield the same directory as new_root. No other | |
2258 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2259 | * | |
4a0d11fa NB |
2260 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2261 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2262 | * in this situation. | |
2263 | * | |
1da177e4 LT |
2264 | * Notes: |
2265 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2266 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2267 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2268 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2269 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2270 | * first. | |
2271 | */ | |
3480b257 HC |
2272 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2273 | const char __user *, put_old) | |
1da177e4 LT |
2274 | { |
2275 | struct vfsmount *tmp; | |
2d8f3038 | 2276 | struct path new, old, parent_path, root_parent, root; |
1da177e4 LT |
2277 | int error; |
2278 | ||
2279 | if (!capable(CAP_SYS_ADMIN)) | |
2280 | return -EPERM; | |
2281 | ||
2d8f3038 | 2282 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2283 | if (error) |
2284 | goto out0; | |
2285 | error = -EINVAL; | |
2d8f3038 | 2286 | if (!check_mnt(new.mnt)) |
1da177e4 LT |
2287 | goto out1; |
2288 | ||
2d8f3038 | 2289 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2290 | if (error) |
2291 | goto out1; | |
2292 | ||
2d8f3038 | 2293 | error = security_sb_pivotroot(&old, &new); |
1da177e4 | 2294 | if (error) { |
2d8f3038 | 2295 | path_put(&old); |
1da177e4 LT |
2296 | goto out1; |
2297 | } | |
2298 | ||
f7ad3c6b | 2299 | get_fs_root(current->fs, &root); |
390c6843 | 2300 | down_write(&namespace_sem); |
2d8f3038 | 2301 | mutex_lock(&old.dentry->d_inode->i_mutex); |
1da177e4 | 2302 | error = -EINVAL; |
2d8f3038 AV |
2303 | if (IS_MNT_SHARED(old.mnt) || |
2304 | IS_MNT_SHARED(new.mnt->mnt_parent) || | |
8c3ee42e | 2305 | IS_MNT_SHARED(root.mnt->mnt_parent)) |
21444403 | 2306 | goto out2; |
8c3ee42e | 2307 | if (!check_mnt(root.mnt)) |
1da177e4 LT |
2308 | goto out2; |
2309 | error = -ENOENT; | |
d83c49f3 | 2310 | if (cant_mount(old.dentry)) |
1da177e4 | 2311 | goto out2; |
f3da392e | 2312 | if (d_unlinked(new.dentry)) |
1da177e4 | 2313 | goto out2; |
f3da392e | 2314 | if (d_unlinked(old.dentry)) |
1da177e4 LT |
2315 | goto out2; |
2316 | error = -EBUSY; | |
2d8f3038 AV |
2317 | if (new.mnt == root.mnt || |
2318 | old.mnt == root.mnt) | |
1da177e4 LT |
2319 | goto out2; /* loop, on the same file system */ |
2320 | error = -EINVAL; | |
8c3ee42e | 2321 | if (root.mnt->mnt_root != root.dentry) |
1da177e4 | 2322 | goto out2; /* not a mountpoint */ |
8c3ee42e | 2323 | if (root.mnt->mnt_parent == root.mnt) |
0bb6fcc1 | 2324 | goto out2; /* not attached */ |
2d8f3038 | 2325 | if (new.mnt->mnt_root != new.dentry) |
1da177e4 | 2326 | goto out2; /* not a mountpoint */ |
2d8f3038 | 2327 | if (new.mnt->mnt_parent == new.mnt) |
0bb6fcc1 | 2328 | goto out2; /* not attached */ |
4ac91378 | 2329 | /* make sure we can reach put_old from new_root */ |
2d8f3038 | 2330 | tmp = old.mnt; |
99b7db7b | 2331 | br_write_lock(vfsmount_lock); |
2d8f3038 | 2332 | if (tmp != new.mnt) { |
1da177e4 LT |
2333 | for (;;) { |
2334 | if (tmp->mnt_parent == tmp) | |
2335 | goto out3; /* already mounted on put_old */ | |
2d8f3038 | 2336 | if (tmp->mnt_parent == new.mnt) |
1da177e4 LT |
2337 | break; |
2338 | tmp = tmp->mnt_parent; | |
2339 | } | |
2d8f3038 | 2340 | if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) |
1da177e4 | 2341 | goto out3; |
2d8f3038 | 2342 | } else if (!is_subdir(old.dentry, new.dentry)) |
1da177e4 | 2343 | goto out3; |
2d8f3038 | 2344 | detach_mnt(new.mnt, &parent_path); |
8c3ee42e | 2345 | detach_mnt(root.mnt, &root_parent); |
4ac91378 | 2346 | /* mount old root on put_old */ |
2d8f3038 | 2347 | attach_mnt(root.mnt, &old); |
4ac91378 | 2348 | /* mount new_root on / */ |
2d8f3038 | 2349 | attach_mnt(new.mnt, &root_parent); |
6b3286ed | 2350 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
99b7db7b | 2351 | br_write_unlock(vfsmount_lock); |
2d8f3038 | 2352 | chroot_fs_refs(&root, &new); |
1da177e4 | 2353 | error = 0; |
1a390689 AV |
2354 | path_put(&root_parent); |
2355 | path_put(&parent_path); | |
1da177e4 | 2356 | out2: |
2d8f3038 | 2357 | mutex_unlock(&old.dentry->d_inode->i_mutex); |
390c6843 | 2358 | up_write(&namespace_sem); |
8c3ee42e | 2359 | path_put(&root); |
2d8f3038 | 2360 | path_put(&old); |
1da177e4 | 2361 | out1: |
2d8f3038 | 2362 | path_put(&new); |
1da177e4 | 2363 | out0: |
1da177e4 LT |
2364 | return error; |
2365 | out3: | |
99b7db7b | 2366 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
2367 | goto out2; |
2368 | } | |
2369 | ||
2370 | static void __init init_mount_tree(void) | |
2371 | { | |
2372 | struct vfsmount *mnt; | |
6b3286ed | 2373 | struct mnt_namespace *ns; |
ac748a09 | 2374 | struct path root; |
1da177e4 LT |
2375 | |
2376 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
2377 | if (IS_ERR(mnt)) | |
2378 | panic("Can't create rootfs"); | |
3b22edc5 TM |
2379 | ns = create_mnt_ns(mnt); |
2380 | if (IS_ERR(ns)) | |
1da177e4 | 2381 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
2382 | |
2383 | init_task.nsproxy->mnt_ns = ns; | |
2384 | get_mnt_ns(ns); | |
2385 | ||
ac748a09 JB |
2386 | root.mnt = ns->root; |
2387 | root.dentry = ns->root->mnt_root; | |
2388 | ||
2389 | set_fs_pwd(current->fs, &root); | |
2390 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
2391 | } |
2392 | ||
74bf17cf | 2393 | void __init mnt_init(void) |
1da177e4 | 2394 | { |
13f14b4d | 2395 | unsigned u; |
15a67dd8 | 2396 | int err; |
1da177e4 | 2397 | |
390c6843 RP |
2398 | init_rwsem(&namespace_sem); |
2399 | ||
1da177e4 | 2400 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
20c2df83 | 2401 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 2402 | |
b58fed8b | 2403 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
2404 | |
2405 | if (!mount_hashtable) | |
2406 | panic("Failed to allocate mount hash table\n"); | |
2407 | ||
13f14b4d ED |
2408 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
2409 | ||
2410 | for (u = 0; u < HASH_SIZE; u++) | |
2411 | INIT_LIST_HEAD(&mount_hashtable[u]); | |
1da177e4 | 2412 | |
99b7db7b NP |
2413 | br_lock_init(vfsmount_lock); |
2414 | ||
15a67dd8 RD |
2415 | err = sysfs_init(); |
2416 | if (err) | |
2417 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 2418 | __func__, err); |
00d26666 GKH |
2419 | fs_kobj = kobject_create_and_add("fs", NULL); |
2420 | if (!fs_kobj) | |
8e24eea7 | 2421 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
2422 | init_rootfs(); |
2423 | init_mount_tree(); | |
2424 | } | |
2425 | ||
616511d0 | 2426 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 2427 | { |
70fbcdf4 | 2428 | LIST_HEAD(umount_list); |
616511d0 | 2429 | |
d498b25a | 2430 | if (!atomic_dec_and_test(&ns->count)) |
616511d0 | 2431 | return; |
390c6843 | 2432 | down_write(&namespace_sem); |
99b7db7b | 2433 | br_write_lock(vfsmount_lock); |
d498b25a | 2434 | umount_tree(ns->root, 0, &umount_list); |
99b7db7b | 2435 | br_write_unlock(vfsmount_lock); |
390c6843 | 2436 | up_write(&namespace_sem); |
70fbcdf4 | 2437 | release_mounts(&umount_list); |
6b3286ed | 2438 | kfree(ns); |
1da177e4 | 2439 | } |
cf8d2c11 | 2440 | EXPORT_SYMBOL(put_mnt_ns); |