Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/namespace.c | |
3 | * | |
4 | * (C) Copyright Al Viro 2000, 2001 | |
5 | * Released under GPL v2. | |
6 | * | |
7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. | |
8 | * Heavily rewritten. | |
9 | */ | |
10 | ||
1da177e4 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 | ||
b3e19d92 NP |
141 | /* |
142 | * vfsmount lock must be held for read | |
143 | */ | |
144 | static inline void mnt_add_count(struct vfsmount *mnt, int n) | |
145 | { | |
146 | #ifdef CONFIG_SMP | |
147 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); | |
148 | #else | |
149 | preempt_disable(); | |
150 | mnt->mnt_count += n; | |
151 | preempt_enable(); | |
152 | #endif | |
153 | } | |
154 | ||
155 | static inline void mnt_set_count(struct vfsmount *mnt, int n) | |
156 | { | |
157 | #ifdef CONFIG_SMP | |
158 | this_cpu_write(mnt->mnt_pcp->mnt_count, n); | |
159 | #else | |
160 | mnt->mnt_count = n; | |
161 | #endif | |
162 | } | |
163 | ||
164 | /* | |
165 | * vfsmount lock must be held for read | |
166 | */ | |
167 | static inline void mnt_inc_count(struct vfsmount *mnt) | |
168 | { | |
169 | mnt_add_count(mnt, 1); | |
170 | } | |
171 | ||
172 | /* | |
173 | * vfsmount lock must be held for read | |
174 | */ | |
175 | static inline void mnt_dec_count(struct vfsmount *mnt) | |
176 | { | |
177 | mnt_add_count(mnt, -1); | |
178 | } | |
179 | ||
180 | /* | |
181 | * vfsmount lock must be held for write | |
182 | */ | |
183 | unsigned int mnt_get_count(struct vfsmount *mnt) | |
184 | { | |
185 | #ifdef CONFIG_SMP | |
186 | unsigned int count = atomic_read(&mnt->mnt_longrefs); | |
187 | int cpu; | |
188 | ||
189 | for_each_possible_cpu(cpu) { | |
190 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; | |
191 | } | |
192 | ||
193 | return count; | |
194 | #else | |
195 | return mnt->mnt_count; | |
196 | #endif | |
197 | } | |
198 | ||
1da177e4 LT |
199 | struct vfsmount *alloc_vfsmnt(const char *name) |
200 | { | |
c3762229 | 201 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
1da177e4 | 202 | if (mnt) { |
73cd49ec MS |
203 | int err; |
204 | ||
205 | err = mnt_alloc_id(mnt); | |
88b38782 LZ |
206 | if (err) |
207 | goto out_free_cache; | |
208 | ||
209 | if (name) { | |
210 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); | |
211 | if (!mnt->mnt_devname) | |
212 | goto out_free_id; | |
73cd49ec MS |
213 | } |
214 | ||
b3e19d92 NP |
215 | #ifdef CONFIG_SMP |
216 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); | |
217 | if (!mnt->mnt_pcp) | |
218 | goto out_free_devname; | |
219 | ||
220 | atomic_set(&mnt->mnt_longrefs, 1); | |
221 | #else | |
222 | mnt->mnt_count = 1; | |
223 | mnt->mnt_writers = 0; | |
224 | #endif | |
225 | ||
1da177e4 LT |
226 | INIT_LIST_HEAD(&mnt->mnt_hash); |
227 | INIT_LIST_HEAD(&mnt->mnt_child); | |
228 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
229 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 230 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 231 | INIT_LIST_HEAD(&mnt->mnt_share); |
a58b0eb8 RP |
232 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
233 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
2504c5d6 AG |
234 | #ifdef CONFIG_FSNOTIFY |
235 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); | |
d3ef3d73 | 236 | #endif |
1da177e4 LT |
237 | } |
238 | return mnt; | |
88b38782 | 239 | |
d3ef3d73 | 240 | #ifdef CONFIG_SMP |
241 | out_free_devname: | |
242 | kfree(mnt->mnt_devname); | |
243 | #endif | |
88b38782 LZ |
244 | out_free_id: |
245 | mnt_free_id(mnt); | |
246 | out_free_cache: | |
247 | kmem_cache_free(mnt_cache, mnt); | |
248 | return NULL; | |
1da177e4 LT |
249 | } |
250 | ||
3d733633 DH |
251 | /* |
252 | * Most r/o checks on a fs are for operations that take | |
253 | * discrete amounts of time, like a write() or unlink(). | |
254 | * We must keep track of when those operations start | |
255 | * (for permission checks) and when they end, so that | |
256 | * we can determine when writes are able to occur to | |
257 | * a filesystem. | |
258 | */ | |
259 | /* | |
260 | * __mnt_is_readonly: check whether a mount is read-only | |
261 | * @mnt: the mount to check for its write status | |
262 | * | |
263 | * This shouldn't be used directly ouside of the VFS. | |
264 | * It does not guarantee that the filesystem will stay | |
265 | * r/w, just that it is right *now*. This can not and | |
266 | * should not be used in place of IS_RDONLY(inode). | |
267 | * mnt_want/drop_write() will _keep_ the filesystem | |
268 | * r/w. | |
269 | */ | |
270 | int __mnt_is_readonly(struct vfsmount *mnt) | |
271 | { | |
2e4b7fcd DH |
272 | if (mnt->mnt_flags & MNT_READONLY) |
273 | return 1; | |
274 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
275 | return 1; | |
276 | return 0; | |
3d733633 DH |
277 | } |
278 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
279 | ||
c6653a83 | 280 | static inline void mnt_inc_writers(struct vfsmount *mnt) |
d3ef3d73 | 281 | { |
282 | #ifdef CONFIG_SMP | |
b3e19d92 | 283 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 284 | #else |
285 | mnt->mnt_writers++; | |
286 | #endif | |
287 | } | |
3d733633 | 288 | |
c6653a83 | 289 | static inline void mnt_dec_writers(struct vfsmount *mnt) |
3d733633 | 290 | { |
d3ef3d73 | 291 | #ifdef CONFIG_SMP |
b3e19d92 | 292 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 293 | #else |
294 | mnt->mnt_writers--; | |
295 | #endif | |
3d733633 | 296 | } |
3d733633 | 297 | |
c6653a83 | 298 | static unsigned int mnt_get_writers(struct vfsmount *mnt) |
3d733633 | 299 | { |
d3ef3d73 | 300 | #ifdef CONFIG_SMP |
301 | unsigned int count = 0; | |
3d733633 | 302 | int cpu; |
3d733633 DH |
303 | |
304 | for_each_possible_cpu(cpu) { | |
b3e19d92 | 305 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 306 | } |
3d733633 | 307 | |
d3ef3d73 | 308 | return count; |
309 | #else | |
310 | return mnt->mnt_writers; | |
311 | #endif | |
3d733633 DH |
312 | } |
313 | ||
8366025e DH |
314 | /* |
315 | * Most r/o checks on a fs are for operations that take | |
316 | * discrete amounts of time, like a write() or unlink(). | |
317 | * We must keep track of when those operations start | |
318 | * (for permission checks) and when they end, so that | |
319 | * we can determine when writes are able to occur to | |
320 | * a filesystem. | |
321 | */ | |
322 | /** | |
323 | * mnt_want_write - get write access to a mount | |
324 | * @mnt: the mount on which to take a write | |
325 | * | |
326 | * This tells the low-level filesystem that a write is | |
327 | * about to be performed to it, and makes sure that | |
328 | * writes are allowed before returning success. When | |
329 | * the write operation is finished, mnt_drop_write() | |
330 | * must be called. This is effectively a refcount. | |
331 | */ | |
332 | int mnt_want_write(struct vfsmount *mnt) | |
333 | { | |
3d733633 | 334 | int ret = 0; |
3d733633 | 335 | |
d3ef3d73 | 336 | preempt_disable(); |
c6653a83 | 337 | mnt_inc_writers(mnt); |
d3ef3d73 | 338 | /* |
c6653a83 | 339 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 | 340 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
341 | * incremented count after it has set MNT_WRITE_HOLD. | |
342 | */ | |
343 | smp_mb(); | |
344 | while (mnt->mnt_flags & MNT_WRITE_HOLD) | |
345 | cpu_relax(); | |
346 | /* | |
347 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
348 | * be set to match its requirements. So we must not load that until | |
349 | * MNT_WRITE_HOLD is cleared. | |
350 | */ | |
351 | smp_rmb(); | |
3d733633 | 352 | if (__mnt_is_readonly(mnt)) { |
c6653a83 | 353 | mnt_dec_writers(mnt); |
3d733633 DH |
354 | ret = -EROFS; |
355 | goto out; | |
356 | } | |
3d733633 | 357 | out: |
d3ef3d73 | 358 | preempt_enable(); |
3d733633 | 359 | return ret; |
8366025e DH |
360 | } |
361 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
362 | ||
96029c4e | 363 | /** |
364 | * mnt_clone_write - get write access to a mount | |
365 | * @mnt: the mount on which to take a write | |
366 | * | |
367 | * This is effectively like mnt_want_write, except | |
368 | * it must only be used to take an extra write reference | |
369 | * on a mountpoint that we already know has a write reference | |
370 | * on it. This allows some optimisation. | |
371 | * | |
372 | * After finished, mnt_drop_write must be called as usual to | |
373 | * drop the reference. | |
374 | */ | |
375 | int mnt_clone_write(struct vfsmount *mnt) | |
376 | { | |
377 | /* superblock may be r/o */ | |
378 | if (__mnt_is_readonly(mnt)) | |
379 | return -EROFS; | |
380 | preempt_disable(); | |
c6653a83 | 381 | mnt_inc_writers(mnt); |
96029c4e | 382 | preempt_enable(); |
383 | return 0; | |
384 | } | |
385 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
386 | ||
387 | /** | |
388 | * mnt_want_write_file - get write access to a file's mount | |
389 | * @file: the file who's mount on which to take a write | |
390 | * | |
391 | * This is like mnt_want_write, but it takes a file and can | |
392 | * do some optimisations if the file is open for write already | |
393 | */ | |
394 | int mnt_want_write_file(struct file *file) | |
395 | { | |
2d8dd38a OH |
396 | struct inode *inode = file->f_dentry->d_inode; |
397 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) | |
96029c4e | 398 | return mnt_want_write(file->f_path.mnt); |
399 | else | |
400 | return mnt_clone_write(file->f_path.mnt); | |
401 | } | |
402 | EXPORT_SYMBOL_GPL(mnt_want_write_file); | |
403 | ||
8366025e DH |
404 | /** |
405 | * mnt_drop_write - give up write access to a mount | |
406 | * @mnt: the mount on which to give up write access | |
407 | * | |
408 | * Tells the low-level filesystem that we are done | |
409 | * performing writes to it. Must be matched with | |
410 | * mnt_want_write() call above. | |
411 | */ | |
412 | void mnt_drop_write(struct vfsmount *mnt) | |
413 | { | |
d3ef3d73 | 414 | preempt_disable(); |
c6653a83 | 415 | mnt_dec_writers(mnt); |
d3ef3d73 | 416 | preempt_enable(); |
8366025e DH |
417 | } |
418 | EXPORT_SYMBOL_GPL(mnt_drop_write); | |
419 | ||
2e4b7fcd | 420 | static int mnt_make_readonly(struct vfsmount *mnt) |
8366025e | 421 | { |
3d733633 DH |
422 | int ret = 0; |
423 | ||
99b7db7b | 424 | br_write_lock(vfsmount_lock); |
d3ef3d73 | 425 | mnt->mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 426 | /* |
d3ef3d73 | 427 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
428 | * should be visible before we do. | |
3d733633 | 429 | */ |
d3ef3d73 | 430 | smp_mb(); |
431 | ||
3d733633 | 432 | /* |
d3ef3d73 | 433 | * With writers on hold, if this value is zero, then there are |
434 | * definitely no active writers (although held writers may subsequently | |
435 | * increment the count, they'll have to wait, and decrement it after | |
436 | * seeing MNT_READONLY). | |
437 | * | |
438 | * It is OK to have counter incremented on one CPU and decremented on | |
439 | * another: the sum will add up correctly. The danger would be when we | |
440 | * sum up each counter, if we read a counter before it is incremented, | |
441 | * but then read another CPU's count which it has been subsequently | |
442 | * decremented from -- we would see more decrements than we should. | |
443 | * MNT_WRITE_HOLD protects against this scenario, because | |
444 | * mnt_want_write first increments count, then smp_mb, then spins on | |
445 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
446 | * we're counting up here. | |
3d733633 | 447 | */ |
c6653a83 | 448 | if (mnt_get_writers(mnt) > 0) |
d3ef3d73 | 449 | ret = -EBUSY; |
450 | else | |
2e4b7fcd | 451 | mnt->mnt_flags |= MNT_READONLY; |
d3ef3d73 | 452 | /* |
453 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
454 | * that become unheld will see MNT_READONLY. | |
455 | */ | |
456 | smp_wmb(); | |
457 | mnt->mnt_flags &= ~MNT_WRITE_HOLD; | |
99b7db7b | 458 | br_write_unlock(vfsmount_lock); |
3d733633 | 459 | return ret; |
8366025e | 460 | } |
8366025e | 461 | |
2e4b7fcd DH |
462 | static void __mnt_unmake_readonly(struct vfsmount *mnt) |
463 | { | |
99b7db7b | 464 | br_write_lock(vfsmount_lock); |
2e4b7fcd | 465 | mnt->mnt_flags &= ~MNT_READONLY; |
99b7db7b | 466 | br_write_unlock(vfsmount_lock); |
2e4b7fcd DH |
467 | } |
468 | ||
a3ec947c | 469 | void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
454e2398 DH |
470 | { |
471 | mnt->mnt_sb = sb; | |
472 | mnt->mnt_root = dget(sb->s_root); | |
454e2398 DH |
473 | } |
474 | ||
475 | EXPORT_SYMBOL(simple_set_mnt); | |
476 | ||
1da177e4 LT |
477 | void free_vfsmnt(struct vfsmount *mnt) |
478 | { | |
479 | kfree(mnt->mnt_devname); | |
73cd49ec | 480 | mnt_free_id(mnt); |
d3ef3d73 | 481 | #ifdef CONFIG_SMP |
b3e19d92 | 482 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 483 | #endif |
1da177e4 LT |
484 | kmem_cache_free(mnt_cache, mnt); |
485 | } | |
486 | ||
487 | /* | |
a05964f3 RP |
488 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
489 | * @dir. If @dir is set return the first mount else return the last mount. | |
99b7db7b | 490 | * vfsmount_lock must be held for read or write. |
1da177e4 | 491 | */ |
a05964f3 RP |
492 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
493 | int dir) | |
1da177e4 | 494 | { |
b58fed8b RP |
495 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
496 | struct list_head *tmp = head; | |
1da177e4 LT |
497 | struct vfsmount *p, *found = NULL; |
498 | ||
1da177e4 | 499 | for (;;) { |
a05964f3 | 500 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
501 | p = NULL; |
502 | if (tmp == head) | |
503 | break; | |
504 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
505 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
a05964f3 | 506 | found = p; |
1da177e4 LT |
507 | break; |
508 | } | |
509 | } | |
1da177e4 LT |
510 | return found; |
511 | } | |
512 | ||
a05964f3 RP |
513 | /* |
514 | * lookup_mnt increments the ref count before returning | |
515 | * the vfsmount struct. | |
516 | */ | |
1c755af4 | 517 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 RP |
518 | { |
519 | struct vfsmount *child_mnt; | |
99b7db7b NP |
520 | |
521 | br_read_lock(vfsmount_lock); | |
1c755af4 | 522 | if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) |
a05964f3 | 523 | mntget(child_mnt); |
99b7db7b | 524 | br_read_unlock(vfsmount_lock); |
a05964f3 RP |
525 | return child_mnt; |
526 | } | |
527 | ||
1da177e4 LT |
528 | static inline int check_mnt(struct vfsmount *mnt) |
529 | { | |
6b3286ed | 530 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
531 | } |
532 | ||
99b7db7b NP |
533 | /* |
534 | * vfsmount lock must be held for write | |
535 | */ | |
6b3286ed | 536 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
537 | { |
538 | if (ns) { | |
539 | ns->event = ++event; | |
540 | wake_up_interruptible(&ns->poll); | |
541 | } | |
542 | } | |
543 | ||
99b7db7b NP |
544 | /* |
545 | * vfsmount lock must be held for write | |
546 | */ | |
6b3286ed | 547 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
548 | { |
549 | if (ns && ns->event != event) { | |
550 | ns->event = event; | |
551 | wake_up_interruptible(&ns->poll); | |
552 | } | |
553 | } | |
554 | ||
5f57cbcc NP |
555 | /* |
556 | * Clear dentry's mounted state if it has no remaining mounts. | |
557 | * vfsmount_lock must be held for write. | |
558 | */ | |
559 | static void dentry_reset_mounted(struct vfsmount *mnt, struct dentry *dentry) | |
560 | { | |
561 | unsigned u; | |
562 | ||
563 | for (u = 0; u < HASH_SIZE; u++) { | |
564 | struct vfsmount *p; | |
565 | ||
566 | list_for_each_entry(p, &mount_hashtable[u], mnt_hash) { | |
567 | if (p->mnt_mountpoint == dentry) | |
568 | return; | |
569 | } | |
570 | } | |
571 | spin_lock(&dentry->d_lock); | |
572 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
573 | spin_unlock(&dentry->d_lock); | |
574 | } | |
575 | ||
99b7db7b NP |
576 | /* |
577 | * vfsmount lock must be held for write | |
578 | */ | |
1a390689 | 579 | static void detach_mnt(struct vfsmount *mnt, struct path *old_path) |
1da177e4 | 580 | { |
1a390689 AV |
581 | old_path->dentry = mnt->mnt_mountpoint; |
582 | old_path->mnt = mnt->mnt_parent; | |
1da177e4 LT |
583 | mnt->mnt_parent = mnt; |
584 | mnt->mnt_mountpoint = mnt->mnt_root; | |
585 | list_del_init(&mnt->mnt_child); | |
586 | list_del_init(&mnt->mnt_hash); | |
5f57cbcc | 587 | dentry_reset_mounted(old_path->mnt, old_path->dentry); |
1da177e4 LT |
588 | } |
589 | ||
99b7db7b NP |
590 | /* |
591 | * vfsmount lock must be held for write | |
592 | */ | |
b90fa9ae RP |
593 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
594 | struct vfsmount *child_mnt) | |
595 | { | |
596 | child_mnt->mnt_parent = mntget(mnt); | |
597 | child_mnt->mnt_mountpoint = dget(dentry); | |
5f57cbcc NP |
598 | spin_lock(&dentry->d_lock); |
599 | dentry->d_flags |= DCACHE_MOUNTED; | |
600 | spin_unlock(&dentry->d_lock); | |
b90fa9ae RP |
601 | } |
602 | ||
99b7db7b NP |
603 | /* |
604 | * vfsmount lock must be held for write | |
605 | */ | |
1a390689 | 606 | static void attach_mnt(struct vfsmount *mnt, struct path *path) |
1da177e4 | 607 | { |
1a390689 | 608 | mnt_set_mountpoint(path->mnt, path->dentry, mnt); |
b90fa9ae | 609 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
1a390689 AV |
610 | hash(path->mnt, path->dentry)); |
611 | list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); | |
b90fa9ae RP |
612 | } |
613 | ||
614 | /* | |
99b7db7b | 615 | * vfsmount lock must be held for write |
b90fa9ae RP |
616 | */ |
617 | static void commit_tree(struct vfsmount *mnt) | |
618 | { | |
619 | struct vfsmount *parent = mnt->mnt_parent; | |
620 | struct vfsmount *m; | |
621 | LIST_HEAD(head); | |
6b3286ed | 622 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae RP |
623 | |
624 | BUG_ON(parent == mnt); | |
625 | ||
626 | list_add_tail(&head, &mnt->mnt_list); | |
627 | list_for_each_entry(m, &head, mnt_list) | |
6b3286ed | 628 | m->mnt_ns = n; |
b90fa9ae RP |
629 | list_splice(&head, n->list.prev); |
630 | ||
631 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
632 | hash(parent, mnt->mnt_mountpoint)); | |
633 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
6b3286ed | 634 | touch_mnt_namespace(n); |
1da177e4 LT |
635 | } |
636 | ||
637 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
638 | { | |
639 | struct list_head *next = p->mnt_mounts.next; | |
640 | if (next == &p->mnt_mounts) { | |
641 | while (1) { | |
642 | if (p == root) | |
643 | return NULL; | |
644 | next = p->mnt_child.next; | |
645 | if (next != &p->mnt_parent->mnt_mounts) | |
646 | break; | |
647 | p = p->mnt_parent; | |
648 | } | |
649 | } | |
650 | return list_entry(next, struct vfsmount, mnt_child); | |
651 | } | |
652 | ||
9676f0c6 RP |
653 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
654 | { | |
655 | struct list_head *prev = p->mnt_mounts.prev; | |
656 | while (prev != &p->mnt_mounts) { | |
657 | p = list_entry(prev, struct vfsmount, mnt_child); | |
658 | prev = p->mnt_mounts.prev; | |
659 | } | |
660 | return p; | |
661 | } | |
662 | ||
36341f64 RP |
663 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
664 | int flag) | |
1da177e4 LT |
665 | { |
666 | struct super_block *sb = old->mnt_sb; | |
667 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
668 | ||
669 | if (mnt) { | |
719f5d7f MS |
670 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
671 | mnt->mnt_group_id = 0; /* not a peer of original */ | |
672 | else | |
673 | mnt->mnt_group_id = old->mnt_group_id; | |
674 | ||
675 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { | |
676 | int err = mnt_alloc_group_id(mnt); | |
677 | if (err) | |
678 | goto out_free; | |
679 | } | |
680 | ||
be1a16a0 | 681 | mnt->mnt_flags = old->mnt_flags & ~MNT_WRITE_HOLD; |
1da177e4 LT |
682 | atomic_inc(&sb->s_active); |
683 | mnt->mnt_sb = sb; | |
684 | mnt->mnt_root = dget(root); | |
685 | mnt->mnt_mountpoint = mnt->mnt_root; | |
686 | mnt->mnt_parent = mnt; | |
b90fa9ae | 687 | |
5afe0022 RP |
688 | if (flag & CL_SLAVE) { |
689 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); | |
690 | mnt->mnt_master = old; | |
691 | CLEAR_MNT_SHARED(mnt); | |
8aec0809 | 692 | } else if (!(flag & CL_PRIVATE)) { |
796a6b52 | 693 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
5afe0022 RP |
694 | list_add(&mnt->mnt_share, &old->mnt_share); |
695 | if (IS_MNT_SLAVE(old)) | |
696 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
697 | mnt->mnt_master = old->mnt_master; | |
698 | } | |
b90fa9ae RP |
699 | if (flag & CL_MAKE_SHARED) |
700 | set_mnt_shared(mnt); | |
1da177e4 LT |
701 | |
702 | /* stick the duplicate mount on the same expiry list | |
703 | * as the original if that was on one */ | |
36341f64 | 704 | if (flag & CL_EXPIRE) { |
36341f64 RP |
705 | if (!list_empty(&old->mnt_expire)) |
706 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
36341f64 | 707 | } |
1da177e4 LT |
708 | } |
709 | return mnt; | |
719f5d7f MS |
710 | |
711 | out_free: | |
712 | free_vfsmnt(mnt); | |
713 | return NULL; | |
1da177e4 LT |
714 | } |
715 | ||
b3e19d92 | 716 | static inline void mntfree(struct vfsmount *mnt) |
1da177e4 LT |
717 | { |
718 | struct super_block *sb = mnt->mnt_sb; | |
b3e19d92 | 719 | |
3d733633 DH |
720 | /* |
721 | * This probably indicates that somebody messed | |
722 | * up a mnt_want/drop_write() pair. If this | |
723 | * happens, the filesystem was probably unable | |
724 | * to make r/w->r/o transitions. | |
725 | */ | |
d3ef3d73 | 726 | /* |
b3e19d92 NP |
727 | * The locking used to deal with mnt_count decrement provides barriers, |
728 | * so mnt_get_writers() below is safe. | |
d3ef3d73 | 729 | */ |
c6653a83 | 730 | WARN_ON(mnt_get_writers(mnt)); |
ca9c726e | 731 | fsnotify_vfsmount_delete(mnt); |
1da177e4 LT |
732 | dput(mnt->mnt_root); |
733 | free_vfsmnt(mnt); | |
734 | deactivate_super(sb); | |
735 | } | |
736 | ||
b3e19d92 NP |
737 | #ifdef CONFIG_SMP |
738 | static inline void __mntput(struct vfsmount *mnt, int longrefs) | |
739 | { | |
740 | if (!longrefs) { | |
741 | put_again: | |
742 | br_read_lock(vfsmount_lock); | |
743 | if (likely(atomic_read(&mnt->mnt_longrefs))) { | |
744 | mnt_dec_count(mnt); | |
745 | br_read_unlock(vfsmount_lock); | |
746 | return; | |
747 | } | |
748 | br_read_unlock(vfsmount_lock); | |
749 | } else { | |
750 | BUG_ON(!atomic_read(&mnt->mnt_longrefs)); | |
751 | if (atomic_add_unless(&mnt->mnt_longrefs, -1, 1)) | |
752 | return; | |
753 | } | |
754 | ||
99b7db7b | 755 | br_write_lock(vfsmount_lock); |
b3e19d92 NP |
756 | if (!longrefs) |
757 | mnt_dec_count(mnt); | |
758 | else | |
759 | atomic_dec(&mnt->mnt_longrefs); | |
760 | if (mnt_get_count(mnt)) { | |
99b7db7b NP |
761 | br_write_unlock(vfsmount_lock); |
762 | return; | |
763 | } | |
b3e19d92 NP |
764 | if (unlikely(mnt->mnt_pinned)) { |
765 | mnt_add_count(mnt, mnt->mnt_pinned + 1); | |
766 | mnt->mnt_pinned = 0; | |
99b7db7b | 767 | br_write_unlock(vfsmount_lock); |
b3e19d92 NP |
768 | acct_auto_close_mnt(mnt); |
769 | goto put_again; | |
770 | } | |
771 | br_write_unlock(vfsmount_lock); | |
772 | mntfree(mnt); | |
773 | } | |
774 | #else | |
775 | static inline void __mntput(struct vfsmount *mnt, int longrefs) | |
776 | { | |
777 | put_again: | |
778 | mnt_dec_count(mnt); | |
779 | if (likely(mnt_get_count(mnt))) | |
99b7db7b | 780 | return; |
b3e19d92 NP |
781 | br_write_lock(vfsmount_lock); |
782 | if (unlikely(mnt->mnt_pinned)) { | |
783 | mnt_add_count(mnt, mnt->mnt_pinned + 1); | |
784 | mnt->mnt_pinned = 0; | |
785 | br_write_unlock(vfsmount_lock); | |
786 | acct_auto_close_mnt(mnt); | |
787 | goto put_again; | |
7b7b1ace | 788 | } |
99b7db7b | 789 | br_write_unlock(vfsmount_lock); |
b3e19d92 NP |
790 | mntfree(mnt); |
791 | } | |
792 | #endif | |
793 | ||
794 | static void mntput_no_expire(struct vfsmount *mnt) | |
795 | { | |
796 | __mntput(mnt, 0); | |
797 | } | |
798 | ||
799 | void mntput(struct vfsmount *mnt) | |
800 | { | |
801 | if (mnt) { | |
802 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ | |
803 | if (unlikely(mnt->mnt_expiry_mark)) | |
804 | mnt->mnt_expiry_mark = 0; | |
805 | __mntput(mnt, 0); | |
806 | } | |
807 | } | |
808 | EXPORT_SYMBOL(mntput); | |
809 | ||
810 | struct vfsmount *mntget(struct vfsmount *mnt) | |
811 | { | |
812 | if (mnt) | |
813 | mnt_inc_count(mnt); | |
814 | return mnt; | |
815 | } | |
816 | EXPORT_SYMBOL(mntget); | |
817 | ||
818 | void mntput_long(struct vfsmount *mnt) | |
819 | { | |
820 | #ifdef CONFIG_SMP | |
821 | if (mnt) { | |
822 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ | |
823 | if (unlikely(mnt->mnt_expiry_mark)) | |
824 | mnt->mnt_expiry_mark = 0; | |
825 | __mntput(mnt, 1); | |
826 | } | |
827 | #else | |
828 | mntput(mnt); | |
829 | #endif | |
7b7b1ace | 830 | } |
b3e19d92 NP |
831 | EXPORT_SYMBOL(mntput_long); |
832 | ||
833 | struct vfsmount *mntget_long(struct vfsmount *mnt) | |
834 | { | |
835 | #ifdef CONFIG_SMP | |
836 | if (mnt) | |
837 | atomic_inc(&mnt->mnt_longrefs); | |
838 | return mnt; | |
839 | #else | |
840 | return mntget(mnt); | |
841 | #endif | |
842 | } | |
843 | EXPORT_SYMBOL(mntget_long); | |
7b7b1ace AV |
844 | |
845 | void mnt_pin(struct vfsmount *mnt) | |
846 | { | |
99b7db7b | 847 | br_write_lock(vfsmount_lock); |
7b7b1ace | 848 | mnt->mnt_pinned++; |
99b7db7b | 849 | br_write_unlock(vfsmount_lock); |
7b7b1ace | 850 | } |
7b7b1ace AV |
851 | EXPORT_SYMBOL(mnt_pin); |
852 | ||
853 | void mnt_unpin(struct vfsmount *mnt) | |
854 | { | |
99b7db7b | 855 | br_write_lock(vfsmount_lock); |
7b7b1ace | 856 | if (mnt->mnt_pinned) { |
b3e19d92 | 857 | mnt_inc_count(mnt); |
7b7b1ace AV |
858 | mnt->mnt_pinned--; |
859 | } | |
99b7db7b | 860 | br_write_unlock(vfsmount_lock); |
7b7b1ace | 861 | } |
7b7b1ace | 862 | EXPORT_SYMBOL(mnt_unpin); |
1da177e4 | 863 | |
b3b304a2 MS |
864 | static inline void mangle(struct seq_file *m, const char *s) |
865 | { | |
866 | seq_escape(m, s, " \t\n\\"); | |
867 | } | |
868 | ||
869 | /* | |
870 | * Simple .show_options callback for filesystems which don't want to | |
871 | * implement more complex mount option showing. | |
872 | * | |
873 | * See also save_mount_options(). | |
874 | */ | |
875 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) | |
876 | { | |
2a32cebd AV |
877 | const char *options; |
878 | ||
879 | rcu_read_lock(); | |
880 | options = rcu_dereference(mnt->mnt_sb->s_options); | |
b3b304a2 MS |
881 | |
882 | if (options != NULL && options[0]) { | |
883 | seq_putc(m, ','); | |
884 | mangle(m, options); | |
885 | } | |
2a32cebd | 886 | rcu_read_unlock(); |
b3b304a2 MS |
887 | |
888 | return 0; | |
889 | } | |
890 | EXPORT_SYMBOL(generic_show_options); | |
891 | ||
892 | /* | |
893 | * If filesystem uses generic_show_options(), this function should be | |
894 | * called from the fill_super() callback. | |
895 | * | |
896 | * The .remount_fs callback usually needs to be handled in a special | |
897 | * way, to make sure, that previous options are not overwritten if the | |
898 | * remount fails. | |
899 | * | |
900 | * Also note, that if the filesystem's .remount_fs function doesn't | |
901 | * reset all options to their default value, but changes only newly | |
902 | * given options, then the displayed options will not reflect reality | |
903 | * any more. | |
904 | */ | |
905 | void save_mount_options(struct super_block *sb, char *options) | |
906 | { | |
2a32cebd AV |
907 | BUG_ON(sb->s_options); |
908 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
909 | } |
910 | EXPORT_SYMBOL(save_mount_options); | |
911 | ||
2a32cebd AV |
912 | void replace_mount_options(struct super_block *sb, char *options) |
913 | { | |
914 | char *old = sb->s_options; | |
915 | rcu_assign_pointer(sb->s_options, options); | |
916 | if (old) { | |
917 | synchronize_rcu(); | |
918 | kfree(old); | |
919 | } | |
920 | } | |
921 | EXPORT_SYMBOL(replace_mount_options); | |
922 | ||
a1a2c409 | 923 | #ifdef CONFIG_PROC_FS |
1da177e4 LT |
924 | /* iterator */ |
925 | static void *m_start(struct seq_file *m, loff_t *pos) | |
926 | { | |
a1a2c409 | 927 | struct proc_mounts *p = m->private; |
1da177e4 | 928 | |
390c6843 | 929 | down_read(&namespace_sem); |
a1a2c409 | 930 | return seq_list_start(&p->ns->list, *pos); |
1da177e4 LT |
931 | } |
932 | ||
933 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
934 | { | |
a1a2c409 | 935 | struct proc_mounts *p = m->private; |
b0765fb8 | 936 | |
a1a2c409 | 937 | return seq_list_next(v, &p->ns->list, pos); |
1da177e4 LT |
938 | } |
939 | ||
940 | static void m_stop(struct seq_file *m, void *v) | |
941 | { | |
390c6843 | 942 | up_read(&namespace_sem); |
1da177e4 LT |
943 | } |
944 | ||
9f5596af AV |
945 | int mnt_had_events(struct proc_mounts *p) |
946 | { | |
947 | struct mnt_namespace *ns = p->ns; | |
948 | int res = 0; | |
949 | ||
99b7db7b | 950 | br_read_lock(vfsmount_lock); |
9f5596af AV |
951 | if (p->event != ns->event) { |
952 | p->event = ns->event; | |
953 | res = 1; | |
954 | } | |
99b7db7b | 955 | br_read_unlock(vfsmount_lock); |
9f5596af AV |
956 | |
957 | return res; | |
958 | } | |
959 | ||
2d4d4864 RP |
960 | struct proc_fs_info { |
961 | int flag; | |
962 | const char *str; | |
963 | }; | |
964 | ||
2069f457 | 965 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
1da177e4 | 966 | { |
2d4d4864 | 967 | static const struct proc_fs_info fs_info[] = { |
1da177e4 LT |
968 | { MS_SYNCHRONOUS, ",sync" }, |
969 | { MS_DIRSYNC, ",dirsync" }, | |
970 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
971 | { 0, NULL } |
972 | }; | |
2d4d4864 RP |
973 | const struct proc_fs_info *fs_infop; |
974 | ||
975 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
976 | if (sb->s_flags & fs_infop->flag) | |
977 | seq_puts(m, fs_infop->str); | |
978 | } | |
2069f457 EP |
979 | |
980 | return security_sb_show_options(m, sb); | |
2d4d4864 RP |
981 | } |
982 | ||
983 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) | |
984 | { | |
985 | static const struct proc_fs_info mnt_info[] = { | |
1da177e4 LT |
986 | { MNT_NOSUID, ",nosuid" }, |
987 | { MNT_NODEV, ",nodev" }, | |
988 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
989 | { MNT_NOATIME, ",noatime" }, |
990 | { MNT_NODIRATIME, ",nodiratime" }, | |
47ae32d6 | 991 | { MNT_RELATIME, ",relatime" }, |
1da177e4 LT |
992 | { 0, NULL } |
993 | }; | |
2d4d4864 RP |
994 | const struct proc_fs_info *fs_infop; |
995 | ||
996 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
997 | if (mnt->mnt_flags & fs_infop->flag) | |
998 | seq_puts(m, fs_infop->str); | |
999 | } | |
1000 | } | |
1001 | ||
1002 | static void show_type(struct seq_file *m, struct super_block *sb) | |
1003 | { | |
1004 | mangle(m, sb->s_type->name); | |
1005 | if (sb->s_subtype && sb->s_subtype[0]) { | |
1006 | seq_putc(m, '.'); | |
1007 | mangle(m, sb->s_subtype); | |
1008 | } | |
1009 | } | |
1010 | ||
1011 | static int show_vfsmnt(struct seq_file *m, void *v) | |
1012 | { | |
1013 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
1014 | int err = 0; | |
c32c2f63 | 1015 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
1da177e4 LT |
1016 | |
1017 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
1018 | seq_putc(m, ' '); | |
c32c2f63 | 1019 | seq_path(m, &mnt_path, " \t\n\\"); |
1da177e4 | 1020 | seq_putc(m, ' '); |
2d4d4864 | 1021 | show_type(m, mnt->mnt_sb); |
2e4b7fcd | 1022 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
2069f457 EP |
1023 | err = show_sb_opts(m, mnt->mnt_sb); |
1024 | if (err) | |
1025 | goto out; | |
2d4d4864 | 1026 | show_mnt_opts(m, mnt); |
1da177e4 LT |
1027 | if (mnt->mnt_sb->s_op->show_options) |
1028 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
1029 | seq_puts(m, " 0 0\n"); | |
2069f457 | 1030 | out: |
1da177e4 LT |
1031 | return err; |
1032 | } | |
1033 | ||
a1a2c409 | 1034 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1035 | .start = m_start, |
1036 | .next = m_next, | |
1037 | .stop = m_stop, | |
1038 | .show = show_vfsmnt | |
1039 | }; | |
1040 | ||
2d4d4864 RP |
1041 | static int show_mountinfo(struct seq_file *m, void *v) |
1042 | { | |
1043 | struct proc_mounts *p = m->private; | |
1044 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
1045 | struct super_block *sb = mnt->mnt_sb; | |
1046 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; | |
1047 | struct path root = p->root; | |
1048 | int err = 0; | |
1049 | ||
1050 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, | |
1051 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); | |
1052 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); | |
1053 | seq_putc(m, ' '); | |
1054 | seq_path_root(m, &mnt_path, &root, " \t\n\\"); | |
1055 | if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { | |
1056 | /* | |
1057 | * Mountpoint is outside root, discard that one. Ugly, | |
1058 | * but less so than trying to do that in iterator in a | |
1059 | * race-free way (due to renames). | |
1060 | */ | |
1061 | return SEQ_SKIP; | |
1062 | } | |
1063 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); | |
1064 | show_mnt_opts(m, mnt); | |
1065 | ||
1066 | /* Tagged fields ("foo:X" or "bar") */ | |
1067 | if (IS_MNT_SHARED(mnt)) | |
1068 | seq_printf(m, " shared:%i", mnt->mnt_group_id); | |
97e7e0f7 MS |
1069 | if (IS_MNT_SLAVE(mnt)) { |
1070 | int master = mnt->mnt_master->mnt_group_id; | |
1071 | int dom = get_dominating_id(mnt, &p->root); | |
1072 | seq_printf(m, " master:%i", master); | |
1073 | if (dom && dom != master) | |
1074 | seq_printf(m, " propagate_from:%i", dom); | |
1075 | } | |
2d4d4864 RP |
1076 | if (IS_MNT_UNBINDABLE(mnt)) |
1077 | seq_puts(m, " unbindable"); | |
1078 | ||
1079 | /* Filesystem specific data */ | |
1080 | seq_puts(m, " - "); | |
1081 | show_type(m, sb); | |
1082 | seq_putc(m, ' '); | |
1083 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
1084 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); | |
2069f457 EP |
1085 | err = show_sb_opts(m, sb); |
1086 | if (err) | |
1087 | goto out; | |
2d4d4864 RP |
1088 | if (sb->s_op->show_options) |
1089 | err = sb->s_op->show_options(m, mnt); | |
1090 | seq_putc(m, '\n'); | |
2069f457 | 1091 | out: |
2d4d4864 RP |
1092 | return err; |
1093 | } | |
1094 | ||
1095 | const struct seq_operations mountinfo_op = { | |
1096 | .start = m_start, | |
1097 | .next = m_next, | |
1098 | .stop = m_stop, | |
1099 | .show = show_mountinfo, | |
1100 | }; | |
1101 | ||
b4629fe2 CL |
1102 | static int show_vfsstat(struct seq_file *m, void *v) |
1103 | { | |
b0765fb8 | 1104 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
c32c2f63 | 1105 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
b4629fe2 CL |
1106 | int err = 0; |
1107 | ||
1108 | /* device */ | |
1109 | if (mnt->mnt_devname) { | |
1110 | seq_puts(m, "device "); | |
1111 | mangle(m, mnt->mnt_devname); | |
1112 | } else | |
1113 | seq_puts(m, "no device"); | |
1114 | ||
1115 | /* mount point */ | |
1116 | seq_puts(m, " mounted on "); | |
c32c2f63 | 1117 | seq_path(m, &mnt_path, " \t\n\\"); |
b4629fe2 CL |
1118 | seq_putc(m, ' '); |
1119 | ||
1120 | /* file system type */ | |
1121 | seq_puts(m, "with fstype "); | |
2d4d4864 | 1122 | show_type(m, mnt->mnt_sb); |
b4629fe2 CL |
1123 | |
1124 | /* optional statistics */ | |
1125 | if (mnt->mnt_sb->s_op->show_stats) { | |
1126 | seq_putc(m, ' '); | |
1127 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); | |
1128 | } | |
1129 | ||
1130 | seq_putc(m, '\n'); | |
1131 | return err; | |
1132 | } | |
1133 | ||
a1a2c409 | 1134 | const struct seq_operations mountstats_op = { |
b4629fe2 CL |
1135 | .start = m_start, |
1136 | .next = m_next, | |
1137 | .stop = m_stop, | |
1138 | .show = show_vfsstat, | |
1139 | }; | |
a1a2c409 | 1140 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1141 | |
1da177e4 LT |
1142 | /** |
1143 | * may_umount_tree - check if a mount tree is busy | |
1144 | * @mnt: root of mount tree | |
1145 | * | |
1146 | * This is called to check if a tree of mounts has any | |
1147 | * open files, pwds, chroots or sub mounts that are | |
1148 | * busy. | |
1149 | */ | |
1150 | int may_umount_tree(struct vfsmount *mnt) | |
1151 | { | |
36341f64 RP |
1152 | int actual_refs = 0; |
1153 | int minimum_refs = 0; | |
1154 | struct vfsmount *p; | |
1da177e4 | 1155 | |
b3e19d92 NP |
1156 | /* write lock needed for mnt_get_count */ |
1157 | br_write_lock(vfsmount_lock); | |
36341f64 | 1158 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
b3e19d92 | 1159 | actual_refs += mnt_get_count(p); |
1da177e4 | 1160 | minimum_refs += 2; |
1da177e4 | 1161 | } |
b3e19d92 | 1162 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
1163 | |
1164 | if (actual_refs > minimum_refs) | |
e3474a8e | 1165 | return 0; |
1da177e4 | 1166 | |
e3474a8e | 1167 | return 1; |
1da177e4 LT |
1168 | } |
1169 | ||
1170 | EXPORT_SYMBOL(may_umount_tree); | |
1171 | ||
1172 | /** | |
1173 | * may_umount - check if a mount point is busy | |
1174 | * @mnt: root of mount | |
1175 | * | |
1176 | * This is called to check if a mount point has any | |
1177 | * open files, pwds, chroots or sub mounts. If the | |
1178 | * mount has sub mounts this will return busy | |
1179 | * regardless of whether the sub mounts are busy. | |
1180 | * | |
1181 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1182 | * give false negatives. The main reason why it's here is that we need | |
1183 | * a non-destructive way to look for easily umountable filesystems. | |
1184 | */ | |
1185 | int may_umount(struct vfsmount *mnt) | |
1186 | { | |
e3474a8e | 1187 | int ret = 1; |
8ad08d8a | 1188 | down_read(&namespace_sem); |
b3e19d92 | 1189 | br_write_lock(vfsmount_lock); |
a05964f3 | 1190 | if (propagate_mount_busy(mnt, 2)) |
e3474a8e | 1191 | ret = 0; |
b3e19d92 | 1192 | br_write_unlock(vfsmount_lock); |
8ad08d8a | 1193 | up_read(&namespace_sem); |
a05964f3 | 1194 | return ret; |
1da177e4 LT |
1195 | } |
1196 | ||
1197 | EXPORT_SYMBOL(may_umount); | |
1198 | ||
b90fa9ae | 1199 | void release_mounts(struct list_head *head) |
70fbcdf4 RP |
1200 | { |
1201 | struct vfsmount *mnt; | |
bf066c7d | 1202 | while (!list_empty(head)) { |
b5e61818 | 1203 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
70fbcdf4 RP |
1204 | list_del_init(&mnt->mnt_hash); |
1205 | if (mnt->mnt_parent != mnt) { | |
1206 | struct dentry *dentry; | |
1207 | struct vfsmount *m; | |
99b7db7b NP |
1208 | |
1209 | br_write_lock(vfsmount_lock); | |
70fbcdf4 RP |
1210 | dentry = mnt->mnt_mountpoint; |
1211 | m = mnt->mnt_parent; | |
1212 | mnt->mnt_mountpoint = mnt->mnt_root; | |
1213 | mnt->mnt_parent = mnt; | |
7c4b93d8 | 1214 | m->mnt_ghosts--; |
99b7db7b | 1215 | br_write_unlock(vfsmount_lock); |
70fbcdf4 RP |
1216 | dput(dentry); |
1217 | mntput(m); | |
1218 | } | |
b3e19d92 | 1219 | mntput_long(mnt); |
70fbcdf4 RP |
1220 | } |
1221 | } | |
1222 | ||
99b7db7b NP |
1223 | /* |
1224 | * vfsmount lock must be held for write | |
1225 | * namespace_sem must be held for write | |
1226 | */ | |
a05964f3 | 1227 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
1da177e4 LT |
1228 | { |
1229 | struct vfsmount *p; | |
1da177e4 | 1230 | |
1bfba4e8 AM |
1231 | for (p = mnt; p; p = next_mnt(p, mnt)) |
1232 | list_move(&p->mnt_hash, kill); | |
1da177e4 | 1233 | |
a05964f3 RP |
1234 | if (propagate) |
1235 | propagate_umount(kill); | |
1236 | ||
70fbcdf4 RP |
1237 | list_for_each_entry(p, kill, mnt_hash) { |
1238 | list_del_init(&p->mnt_expire); | |
1239 | list_del_init(&p->mnt_list); | |
6b3286ed KK |
1240 | __touch_mnt_namespace(p->mnt_ns); |
1241 | p->mnt_ns = NULL; | |
70fbcdf4 | 1242 | list_del_init(&p->mnt_child); |
7c4b93d8 AV |
1243 | if (p->mnt_parent != p) { |
1244 | p->mnt_parent->mnt_ghosts++; | |
5f57cbcc | 1245 | dentry_reset_mounted(p->mnt_parent, p->mnt_mountpoint); |
7c4b93d8 | 1246 | } |
a05964f3 | 1247 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
1248 | } |
1249 | } | |
1250 | ||
c35038be AV |
1251 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); |
1252 | ||
1da177e4 LT |
1253 | static int do_umount(struct vfsmount *mnt, int flags) |
1254 | { | |
b58fed8b | 1255 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 1256 | int retval; |
70fbcdf4 | 1257 | LIST_HEAD(umount_list); |
1da177e4 LT |
1258 | |
1259 | retval = security_sb_umount(mnt, flags); | |
1260 | if (retval) | |
1261 | return retval; | |
1262 | ||
1263 | /* | |
1264 | * Allow userspace to request a mountpoint be expired rather than | |
1265 | * unmounting unconditionally. Unmount only happens if: | |
1266 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1267 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1268 | */ | |
1269 | if (flags & MNT_EXPIRE) { | |
6ac08c39 | 1270 | if (mnt == current->fs->root.mnt || |
1da177e4 LT |
1271 | flags & (MNT_FORCE | MNT_DETACH)) |
1272 | return -EINVAL; | |
1273 | ||
b3e19d92 NP |
1274 | /* |
1275 | * probably don't strictly need the lock here if we examined | |
1276 | * all race cases, but it's a slowpath. | |
1277 | */ | |
1278 | br_write_lock(vfsmount_lock); | |
1279 | if (mnt_get_count(mnt) != 2) { | |
1280 | br_write_lock(vfsmount_lock); | |
1da177e4 | 1281 | return -EBUSY; |
b3e19d92 NP |
1282 | } |
1283 | br_write_unlock(vfsmount_lock); | |
1da177e4 LT |
1284 | |
1285 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
1286 | return -EAGAIN; | |
1287 | } | |
1288 | ||
1289 | /* | |
1290 | * If we may have to abort operations to get out of this | |
1291 | * mount, and they will themselves hold resources we must | |
1292 | * allow the fs to do things. In the Unix tradition of | |
1293 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1294 | * might fail to complete on the first run through as other tasks | |
1295 | * must return, and the like. Thats for the mount program to worry | |
1296 | * about for the moment. | |
1297 | */ | |
1298 | ||
42faad99 | 1299 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1300 | sb->s_op->umount_begin(sb); |
42faad99 | 1301 | } |
1da177e4 LT |
1302 | |
1303 | /* | |
1304 | * No sense to grab the lock for this test, but test itself looks | |
1305 | * somewhat bogus. Suggestions for better replacement? | |
1306 | * Ho-hum... In principle, we might treat that as umount + switch | |
1307 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1308 | * Actually it makes sense, especially if rootfs would contain a | |
1309 | * /reboot - static binary that would close all descriptors and | |
1310 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1311 | */ | |
6ac08c39 | 1312 | if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1313 | /* |
1314 | * Special case for "unmounting" root ... | |
1315 | * we just try to remount it readonly. | |
1316 | */ | |
1317 | down_write(&sb->s_umount); | |
4aa98cf7 | 1318 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1319 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1320 | up_write(&sb->s_umount); |
1321 | return retval; | |
1322 | } | |
1323 | ||
390c6843 | 1324 | down_write(&namespace_sem); |
99b7db7b | 1325 | br_write_lock(vfsmount_lock); |
5addc5dd | 1326 | event++; |
1da177e4 | 1327 | |
c35038be AV |
1328 | if (!(flags & MNT_DETACH)) |
1329 | shrink_submounts(mnt, &umount_list); | |
1330 | ||
1da177e4 | 1331 | retval = -EBUSY; |
a05964f3 | 1332 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1da177e4 | 1333 | if (!list_empty(&mnt->mnt_list)) |
a05964f3 | 1334 | umount_tree(mnt, 1, &umount_list); |
1da177e4 LT |
1335 | retval = 0; |
1336 | } | |
99b7db7b | 1337 | br_write_unlock(vfsmount_lock); |
390c6843 | 1338 | up_write(&namespace_sem); |
70fbcdf4 | 1339 | release_mounts(&umount_list); |
1da177e4 LT |
1340 | return retval; |
1341 | } | |
1342 | ||
1343 | /* | |
1344 | * Now umount can handle mount points as well as block devices. | |
1345 | * This is important for filesystems which use unnamed block devices. | |
1346 | * | |
1347 | * We now support a flag for forced unmount like the other 'big iron' | |
1348 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1349 | */ | |
1350 | ||
bdc480e3 | 1351 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1352 | { |
2d8f3038 | 1353 | struct path path; |
1da177e4 | 1354 | int retval; |
db1f05bb | 1355 | int lookup_flags = 0; |
1da177e4 | 1356 | |
db1f05bb MS |
1357 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
1358 | return -EINVAL; | |
1359 | ||
1360 | if (!(flags & UMOUNT_NOFOLLOW)) | |
1361 | lookup_flags |= LOOKUP_FOLLOW; | |
1362 | ||
1363 | retval = user_path_at(AT_FDCWD, name, lookup_flags, &path); | |
1da177e4 LT |
1364 | if (retval) |
1365 | goto out; | |
1366 | retval = -EINVAL; | |
2d8f3038 | 1367 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1368 | goto dput_and_out; |
2d8f3038 | 1369 | if (!check_mnt(path.mnt)) |
1da177e4 LT |
1370 | goto dput_and_out; |
1371 | ||
1372 | retval = -EPERM; | |
1373 | if (!capable(CAP_SYS_ADMIN)) | |
1374 | goto dput_and_out; | |
1375 | ||
2d8f3038 | 1376 | retval = do_umount(path.mnt, flags); |
1da177e4 | 1377 | dput_and_out: |
429731b1 | 1378 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 AV |
1379 | dput(path.dentry); |
1380 | mntput_no_expire(path.mnt); | |
1da177e4 LT |
1381 | out: |
1382 | return retval; | |
1383 | } | |
1384 | ||
1385 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1386 | ||
1387 | /* | |
b58fed8b | 1388 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1389 | */ |
bdc480e3 | 1390 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1391 | { |
b58fed8b | 1392 | return sys_umount(name, 0); |
1da177e4 LT |
1393 | } |
1394 | ||
1395 | #endif | |
1396 | ||
2d92ab3c | 1397 | static int mount_is_safe(struct path *path) |
1da177e4 LT |
1398 | { |
1399 | if (capable(CAP_SYS_ADMIN)) | |
1400 | return 0; | |
1401 | return -EPERM; | |
1402 | #ifdef notyet | |
2d92ab3c | 1403 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
1da177e4 | 1404 | return -EPERM; |
2d92ab3c | 1405 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
da9592ed | 1406 | if (current_uid() != path->dentry->d_inode->i_uid) |
1da177e4 LT |
1407 | return -EPERM; |
1408 | } | |
2d92ab3c | 1409 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
1da177e4 LT |
1410 | return -EPERM; |
1411 | return 0; | |
1412 | #endif | |
1413 | } | |
1414 | ||
b90fa9ae | 1415 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
36341f64 | 1416 | int flag) |
1da177e4 LT |
1417 | { |
1418 | struct vfsmount *res, *p, *q, *r, *s; | |
1a390689 | 1419 | struct path path; |
1da177e4 | 1420 | |
9676f0c6 RP |
1421 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
1422 | return NULL; | |
1423 | ||
36341f64 | 1424 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
1425 | if (!q) |
1426 | goto Enomem; | |
1427 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
1428 | ||
1429 | p = mnt; | |
fdadd65f | 1430 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
7ec02ef1 | 1431 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1432 | continue; |
1433 | ||
1434 | for (s = r; s; s = next_mnt(s, r)) { | |
9676f0c6 RP |
1435 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
1436 | s = skip_mnt_tree(s); | |
1437 | continue; | |
1438 | } | |
1da177e4 LT |
1439 | while (p != s->mnt_parent) { |
1440 | p = p->mnt_parent; | |
1441 | q = q->mnt_parent; | |
1442 | } | |
1443 | p = s; | |
1a390689 AV |
1444 | path.mnt = q; |
1445 | path.dentry = p->mnt_mountpoint; | |
36341f64 | 1446 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
1447 | if (!q) |
1448 | goto Enomem; | |
99b7db7b | 1449 | br_write_lock(vfsmount_lock); |
1da177e4 | 1450 | list_add_tail(&q->mnt_list, &res->mnt_list); |
1a390689 | 1451 | attach_mnt(q, &path); |
99b7db7b | 1452 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
1453 | } |
1454 | } | |
1455 | return res; | |
b58fed8b | 1456 | Enomem: |
1da177e4 | 1457 | if (res) { |
70fbcdf4 | 1458 | LIST_HEAD(umount_list); |
99b7db7b | 1459 | br_write_lock(vfsmount_lock); |
a05964f3 | 1460 | umount_tree(res, 0, &umount_list); |
99b7db7b | 1461 | br_write_unlock(vfsmount_lock); |
70fbcdf4 | 1462 | release_mounts(&umount_list); |
1da177e4 LT |
1463 | } |
1464 | return NULL; | |
1465 | } | |
1466 | ||
589ff870 | 1467 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 AV |
1468 | { |
1469 | struct vfsmount *tree; | |
1a60a280 | 1470 | down_write(&namespace_sem); |
589ff870 | 1471 | tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); |
1a60a280 | 1472 | up_write(&namespace_sem); |
8aec0809 AV |
1473 | return tree; |
1474 | } | |
1475 | ||
1476 | void drop_collected_mounts(struct vfsmount *mnt) | |
1477 | { | |
1478 | LIST_HEAD(umount_list); | |
1a60a280 | 1479 | down_write(&namespace_sem); |
99b7db7b | 1480 | br_write_lock(vfsmount_lock); |
8aec0809 | 1481 | umount_tree(mnt, 0, &umount_list); |
99b7db7b | 1482 | br_write_unlock(vfsmount_lock); |
1a60a280 | 1483 | up_write(&namespace_sem); |
8aec0809 AV |
1484 | release_mounts(&umount_list); |
1485 | } | |
1486 | ||
1f707137 AV |
1487 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1488 | struct vfsmount *root) | |
1489 | { | |
1490 | struct vfsmount *mnt; | |
1491 | int res = f(root, arg); | |
1492 | if (res) | |
1493 | return res; | |
1494 | list_for_each_entry(mnt, &root->mnt_list, mnt_list) { | |
1495 | res = f(mnt, arg); | |
1496 | if (res) | |
1497 | return res; | |
1498 | } | |
1499 | return 0; | |
1500 | } | |
1501 | ||
719f5d7f MS |
1502 | static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) |
1503 | { | |
1504 | struct vfsmount *p; | |
1505 | ||
1506 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { | |
1507 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) | |
1508 | mnt_release_group_id(p); | |
1509 | } | |
1510 | } | |
1511 | ||
1512 | static int invent_group_ids(struct vfsmount *mnt, bool recurse) | |
1513 | { | |
1514 | struct vfsmount *p; | |
1515 | ||
1516 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { | |
1517 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { | |
1518 | int err = mnt_alloc_group_id(p); | |
1519 | if (err) { | |
1520 | cleanup_group_ids(mnt, p); | |
1521 | return err; | |
1522 | } | |
1523 | } | |
1524 | } | |
1525 | ||
1526 | return 0; | |
1527 | } | |
1528 | ||
b90fa9ae RP |
1529 | /* |
1530 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1531 | * @nd : place the mount tree @source_mnt is attached |
1532 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1533 | * store the parent mount and mountpoint dentry. | |
1534 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1535 | * |
1536 | * NOTE: in the table below explains the semantics when a source mount | |
1537 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1538 | * --------------------------------------------------------------------------- |
1539 | * | BIND MOUNT OPERATION | | |
1540 | * |************************************************************************** | |
1541 | * | source-->| shared | private | slave | unbindable | | |
1542 | * | dest | | | | | | |
1543 | * | | | | | | | | |
1544 | * | v | | | | | | |
1545 | * |************************************************************************** | |
1546 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1547 | * | | | | | | | |
1548 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1549 | * *************************************************************************** | |
b90fa9ae RP |
1550 | * A bind operation clones the source mount and mounts the clone on the |
1551 | * destination mount. | |
1552 | * | |
1553 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1554 | * tree of the destination mount and the cloned mount is added to | |
1555 | * the peer group of the source mount. | |
1556 | * (+) the cloned mount is created under the destination mount and is marked | |
1557 | * as shared. The cloned mount is added to the peer group of the source | |
1558 | * mount. | |
5afe0022 RP |
1559 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1560 | * of the destination mount and the cloned mount is made slave | |
1561 | * of the same master as that of the source mount. The cloned mount | |
1562 | * is marked as 'shared and slave'. | |
1563 | * (*) the cloned mount is made a slave of the same master as that of the | |
1564 | * source mount. | |
1565 | * | |
9676f0c6 RP |
1566 | * --------------------------------------------------------------------------- |
1567 | * | MOVE MOUNT OPERATION | | |
1568 | * |************************************************************************** | |
1569 | * | source-->| shared | private | slave | unbindable | | |
1570 | * | dest | | | | | | |
1571 | * | | | | | | | | |
1572 | * | v | | | | | | |
1573 | * |************************************************************************** | |
1574 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1575 | * | | | | | | | |
1576 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1577 | * *************************************************************************** | |
5afe0022 RP |
1578 | * |
1579 | * (+) the mount is moved to the destination. And is then propagated to | |
1580 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1581 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1582 | * (+++) the mount is moved to the destination and is then propagated to |
1583 | * all the mounts belonging to the destination mount's propagation tree. | |
1584 | * the mount is marked as 'shared and slave'. | |
1585 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1586 | * |
1587 | * if the source mount is a tree, the operations explained above is | |
1588 | * applied to each mount in the tree. | |
1589 | * Must be called without spinlocks held, since this function can sleep | |
1590 | * in allocations. | |
1591 | */ | |
1592 | static int attach_recursive_mnt(struct vfsmount *source_mnt, | |
1a390689 | 1593 | struct path *path, struct path *parent_path) |
b90fa9ae RP |
1594 | { |
1595 | LIST_HEAD(tree_list); | |
1a390689 AV |
1596 | struct vfsmount *dest_mnt = path->mnt; |
1597 | struct dentry *dest_dentry = path->dentry; | |
b90fa9ae | 1598 | struct vfsmount *child, *p; |
719f5d7f | 1599 | int err; |
b90fa9ae | 1600 | |
719f5d7f MS |
1601 | if (IS_MNT_SHARED(dest_mnt)) { |
1602 | err = invent_group_ids(source_mnt, true); | |
1603 | if (err) | |
1604 | goto out; | |
1605 | } | |
1606 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); | |
1607 | if (err) | |
1608 | goto out_cleanup_ids; | |
b90fa9ae | 1609 | |
99b7db7b | 1610 | br_write_lock(vfsmount_lock); |
df1a1ad2 | 1611 | |
b90fa9ae RP |
1612 | if (IS_MNT_SHARED(dest_mnt)) { |
1613 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) | |
1614 | set_mnt_shared(p); | |
1615 | } | |
1a390689 AV |
1616 | if (parent_path) { |
1617 | detach_mnt(source_mnt, parent_path); | |
1618 | attach_mnt(source_mnt, path); | |
e5d67f07 | 1619 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
21444403 RP |
1620 | } else { |
1621 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); | |
1622 | commit_tree(source_mnt); | |
1623 | } | |
b90fa9ae RP |
1624 | |
1625 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { | |
1626 | list_del_init(&child->mnt_hash); | |
1627 | commit_tree(child); | |
1628 | } | |
99b7db7b NP |
1629 | br_write_unlock(vfsmount_lock); |
1630 | ||
b90fa9ae | 1631 | return 0; |
719f5d7f MS |
1632 | |
1633 | out_cleanup_ids: | |
1634 | if (IS_MNT_SHARED(dest_mnt)) | |
1635 | cleanup_group_ids(source_mnt, NULL); | |
1636 | out: | |
1637 | return err; | |
b90fa9ae RP |
1638 | } |
1639 | ||
8c3ee42e | 1640 | static int graft_tree(struct vfsmount *mnt, struct path *path) |
1da177e4 LT |
1641 | { |
1642 | int err; | |
1643 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
1644 | return -EINVAL; | |
1645 | ||
8c3ee42e | 1646 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1da177e4 LT |
1647 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
1648 | return -ENOTDIR; | |
1649 | ||
1650 | err = -ENOENT; | |
8c3ee42e | 1651 | mutex_lock(&path->dentry->d_inode->i_mutex); |
d83c49f3 | 1652 | if (cant_mount(path->dentry)) |
1da177e4 LT |
1653 | goto out_unlock; |
1654 | ||
f3da392e | 1655 | if (!d_unlinked(path->dentry)) |
8c3ee42e | 1656 | err = attach_recursive_mnt(mnt, path, NULL); |
1da177e4 | 1657 | out_unlock: |
8c3ee42e | 1658 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 LT |
1659 | return err; |
1660 | } | |
1661 | ||
7a2e8a8f VA |
1662 | /* |
1663 | * Sanity check the flags to change_mnt_propagation. | |
1664 | */ | |
1665 | ||
1666 | static int flags_to_propagation_type(int flags) | |
1667 | { | |
1668 | int type = flags & ~MS_REC; | |
1669 | ||
1670 | /* Fail if any non-propagation flags are set */ | |
1671 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
1672 | return 0; | |
1673 | /* Only one propagation flag should be set */ | |
1674 | if (!is_power_of_2(type)) | |
1675 | return 0; | |
1676 | return type; | |
1677 | } | |
1678 | ||
07b20889 RP |
1679 | /* |
1680 | * recursively change the type of the mountpoint. | |
1681 | */ | |
0a0d8a46 | 1682 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1683 | { |
2d92ab3c | 1684 | struct vfsmount *m, *mnt = path->mnt; |
07b20889 | 1685 | int recurse = flag & MS_REC; |
7a2e8a8f | 1686 | int type; |
719f5d7f | 1687 | int err = 0; |
07b20889 | 1688 | |
ee6f9582 MS |
1689 | if (!capable(CAP_SYS_ADMIN)) |
1690 | return -EPERM; | |
1691 | ||
2d92ab3c | 1692 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
1693 | return -EINVAL; |
1694 | ||
7a2e8a8f VA |
1695 | type = flags_to_propagation_type(flag); |
1696 | if (!type) | |
1697 | return -EINVAL; | |
1698 | ||
07b20889 | 1699 | down_write(&namespace_sem); |
719f5d7f MS |
1700 | if (type == MS_SHARED) { |
1701 | err = invent_group_ids(mnt, recurse); | |
1702 | if (err) | |
1703 | goto out_unlock; | |
1704 | } | |
1705 | ||
99b7db7b | 1706 | br_write_lock(vfsmount_lock); |
07b20889 RP |
1707 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
1708 | change_mnt_propagation(m, type); | |
99b7db7b | 1709 | br_write_unlock(vfsmount_lock); |
719f5d7f MS |
1710 | |
1711 | out_unlock: | |
07b20889 | 1712 | up_write(&namespace_sem); |
719f5d7f | 1713 | return err; |
07b20889 RP |
1714 | } |
1715 | ||
1da177e4 LT |
1716 | /* |
1717 | * do loopback mount. | |
1718 | */ | |
0a0d8a46 | 1719 | static int do_loopback(struct path *path, char *old_name, |
2dafe1c4 | 1720 | int recurse) |
1da177e4 | 1721 | { |
2d92ab3c | 1722 | struct path old_path; |
1da177e4 | 1723 | struct vfsmount *mnt = NULL; |
2d92ab3c | 1724 | int err = mount_is_safe(path); |
1da177e4 LT |
1725 | if (err) |
1726 | return err; | |
1727 | if (!old_name || !*old_name) | |
1728 | return -EINVAL; | |
2d92ab3c | 1729 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1730 | if (err) |
1731 | return err; | |
1732 | ||
390c6843 | 1733 | down_write(&namespace_sem); |
1da177e4 | 1734 | err = -EINVAL; |
2d92ab3c | 1735 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
4ac91378 | 1736 | goto out; |
9676f0c6 | 1737 | |
2d92ab3c | 1738 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
ccd48bc7 | 1739 | goto out; |
1da177e4 | 1740 | |
ccd48bc7 AV |
1741 | err = -ENOMEM; |
1742 | if (recurse) | |
2d92ab3c | 1743 | mnt = copy_tree(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 | 1744 | else |
2d92ab3c | 1745 | mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 AV |
1746 | |
1747 | if (!mnt) | |
1748 | goto out; | |
1749 | ||
2d92ab3c | 1750 | err = graft_tree(mnt, path); |
ccd48bc7 | 1751 | if (err) { |
70fbcdf4 | 1752 | LIST_HEAD(umount_list); |
99b7db7b NP |
1753 | |
1754 | br_write_lock(vfsmount_lock); | |
a05964f3 | 1755 | umount_tree(mnt, 0, &umount_list); |
99b7db7b | 1756 | br_write_unlock(vfsmount_lock); |
70fbcdf4 | 1757 | release_mounts(&umount_list); |
5b83d2c5 | 1758 | } |
1da177e4 | 1759 | |
ccd48bc7 | 1760 | out: |
390c6843 | 1761 | up_write(&namespace_sem); |
2d92ab3c | 1762 | path_put(&old_path); |
1da177e4 LT |
1763 | return err; |
1764 | } | |
1765 | ||
2e4b7fcd DH |
1766 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
1767 | { | |
1768 | int error = 0; | |
1769 | int readonly_request = 0; | |
1770 | ||
1771 | if (ms_flags & MS_RDONLY) | |
1772 | readonly_request = 1; | |
1773 | if (readonly_request == __mnt_is_readonly(mnt)) | |
1774 | return 0; | |
1775 | ||
1776 | if (readonly_request) | |
1777 | error = mnt_make_readonly(mnt); | |
1778 | else | |
1779 | __mnt_unmake_readonly(mnt); | |
1780 | return error; | |
1781 | } | |
1782 | ||
1da177e4 LT |
1783 | /* |
1784 | * change filesystem flags. dir should be a physical root of filesystem. | |
1785 | * If you've mounted a non-root directory somewhere and want to do remount | |
1786 | * on it - tough luck. | |
1787 | */ | |
0a0d8a46 | 1788 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
1789 | void *data) |
1790 | { | |
1791 | int err; | |
2d92ab3c | 1792 | struct super_block *sb = path->mnt->mnt_sb; |
1da177e4 LT |
1793 | |
1794 | if (!capable(CAP_SYS_ADMIN)) | |
1795 | return -EPERM; | |
1796 | ||
2d92ab3c | 1797 | if (!check_mnt(path->mnt)) |
1da177e4 LT |
1798 | return -EINVAL; |
1799 | ||
2d92ab3c | 1800 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
1801 | return -EINVAL; |
1802 | ||
1803 | down_write(&sb->s_umount); | |
2e4b7fcd | 1804 | if (flags & MS_BIND) |
2d92ab3c | 1805 | err = change_mount_flags(path->mnt, flags); |
4aa98cf7 | 1806 | else |
2e4b7fcd | 1807 | err = do_remount_sb(sb, flags, data, 0); |
7b43a79f | 1808 | if (!err) { |
99b7db7b | 1809 | br_write_lock(vfsmount_lock); |
495d6c9c | 1810 | mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK; |
2d92ab3c | 1811 | path->mnt->mnt_flags = mnt_flags; |
99b7db7b | 1812 | br_write_unlock(vfsmount_lock); |
7b43a79f | 1813 | } |
1da177e4 | 1814 | up_write(&sb->s_umount); |
0e55a7cc | 1815 | if (!err) { |
99b7db7b | 1816 | br_write_lock(vfsmount_lock); |
0e55a7cc | 1817 | touch_mnt_namespace(path->mnt->mnt_ns); |
99b7db7b | 1818 | br_write_unlock(vfsmount_lock); |
0e55a7cc | 1819 | } |
1da177e4 LT |
1820 | return err; |
1821 | } | |
1822 | ||
9676f0c6 RP |
1823 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
1824 | { | |
1825 | struct vfsmount *p; | |
1826 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
1827 | if (IS_MNT_UNBINDABLE(p)) | |
1828 | return 1; | |
1829 | } | |
1830 | return 0; | |
1831 | } | |
1832 | ||
0a0d8a46 | 1833 | static int do_move_mount(struct path *path, char *old_name) |
1da177e4 | 1834 | { |
2d92ab3c | 1835 | struct path old_path, parent_path; |
1da177e4 LT |
1836 | struct vfsmount *p; |
1837 | int err = 0; | |
1838 | if (!capable(CAP_SYS_ADMIN)) | |
1839 | return -EPERM; | |
1840 | if (!old_name || !*old_name) | |
1841 | return -EINVAL; | |
2d92ab3c | 1842 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1843 | if (err) |
1844 | return err; | |
1845 | ||
390c6843 | 1846 | down_write(&namespace_sem); |
2d92ab3c | 1847 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1848 | follow_down(path)) |
1da177e4 LT |
1849 | ; |
1850 | err = -EINVAL; | |
2d92ab3c | 1851 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
1da177e4 LT |
1852 | goto out; |
1853 | ||
1854 | err = -ENOENT; | |
2d92ab3c | 1855 | mutex_lock(&path->dentry->d_inode->i_mutex); |
d83c49f3 | 1856 | if (cant_mount(path->dentry)) |
1da177e4 LT |
1857 | goto out1; |
1858 | ||
f3da392e | 1859 | if (d_unlinked(path->dentry)) |
21444403 | 1860 | goto out1; |
1da177e4 LT |
1861 | |
1862 | err = -EINVAL; | |
2d92ab3c | 1863 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 1864 | goto out1; |
1da177e4 | 1865 | |
2d92ab3c | 1866 | if (old_path.mnt == old_path.mnt->mnt_parent) |
21444403 | 1867 | goto out1; |
1da177e4 | 1868 | |
2d92ab3c AV |
1869 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1870 | S_ISDIR(old_path.dentry->d_inode->i_mode)) | |
21444403 RP |
1871 | goto out1; |
1872 | /* | |
1873 | * Don't move a mount residing in a shared parent. | |
1874 | */ | |
2d92ab3c AV |
1875 | if (old_path.mnt->mnt_parent && |
1876 | IS_MNT_SHARED(old_path.mnt->mnt_parent)) | |
21444403 | 1877 | goto out1; |
9676f0c6 RP |
1878 | /* |
1879 | * Don't move a mount tree containing unbindable mounts to a destination | |
1880 | * mount which is shared. | |
1881 | */ | |
2d92ab3c AV |
1882 | if (IS_MNT_SHARED(path->mnt) && |
1883 | tree_contains_unbindable(old_path.mnt)) | |
9676f0c6 | 1884 | goto out1; |
1da177e4 | 1885 | err = -ELOOP; |
2d92ab3c AV |
1886 | for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1887 | if (p == old_path.mnt) | |
21444403 | 1888 | goto out1; |
1da177e4 | 1889 | |
2d92ab3c | 1890 | err = attach_recursive_mnt(old_path.mnt, path, &parent_path); |
4ac91378 | 1891 | if (err) |
21444403 | 1892 | goto out1; |
1da177e4 LT |
1893 | |
1894 | /* if the mount is moved, it should no longer be expire | |
1895 | * automatically */ | |
2d92ab3c | 1896 | list_del_init(&old_path.mnt->mnt_expire); |
1da177e4 | 1897 | out1: |
2d92ab3c | 1898 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 | 1899 | out: |
390c6843 | 1900 | up_write(&namespace_sem); |
1da177e4 | 1901 | if (!err) |
1a390689 | 1902 | path_put(&parent_path); |
2d92ab3c | 1903 | path_put(&old_path); |
1da177e4 LT |
1904 | return err; |
1905 | } | |
1906 | ||
1907 | /* | |
1908 | * create a new mount for userspace and request it to be added into the | |
1909 | * namespace's tree | |
1910 | */ | |
0a0d8a46 | 1911 | static int do_new_mount(struct path *path, char *type, int flags, |
1da177e4 LT |
1912 | int mnt_flags, char *name, void *data) |
1913 | { | |
1914 | struct vfsmount *mnt; | |
1915 | ||
eca6f534 | 1916 | if (!type) |
1da177e4 LT |
1917 | return -EINVAL; |
1918 | ||
1919 | /* we need capabilities... */ | |
1920 | if (!capable(CAP_SYS_ADMIN)) | |
1921 | return -EPERM; | |
1922 | ||
1923 | mnt = do_kern_mount(type, flags, name, data); | |
1924 | if (IS_ERR(mnt)) | |
1925 | return PTR_ERR(mnt); | |
1926 | ||
2d92ab3c | 1927 | return do_add_mount(mnt, path, mnt_flags, NULL); |
1da177e4 LT |
1928 | } |
1929 | ||
1930 | /* | |
1931 | * add a mount into a namespace's mount tree | |
1932 | * - provide the option of adding the new mount to an expiration list | |
1933 | */ | |
8d66bf54 | 1934 | int do_add_mount(struct vfsmount *newmnt, struct path *path, |
1da177e4 LT |
1935 | int mnt_flags, struct list_head *fslist) |
1936 | { | |
1937 | int err; | |
1938 | ||
8089352a | 1939 | mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); |
27d55f1f | 1940 | |
390c6843 | 1941 | down_write(&namespace_sem); |
1da177e4 | 1942 | /* Something was mounted here while we slept */ |
8d66bf54 | 1943 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1944 | follow_down(path)) |
1da177e4 LT |
1945 | ; |
1946 | err = -EINVAL; | |
dd5cae6e | 1947 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) |
1da177e4 LT |
1948 | goto unlock; |
1949 | ||
1950 | /* Refuse the same filesystem on the same mount point */ | |
1951 | err = -EBUSY; | |
8d66bf54 AV |
1952 | if (path->mnt->mnt_sb == newmnt->mnt_sb && |
1953 | path->mnt->mnt_root == path->dentry) | |
1da177e4 LT |
1954 | goto unlock; |
1955 | ||
1956 | err = -EINVAL; | |
1957 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
1958 | goto unlock; | |
1959 | ||
1960 | newmnt->mnt_flags = mnt_flags; | |
8d66bf54 | 1961 | if ((err = graft_tree(newmnt, path))) |
5b83d2c5 | 1962 | goto unlock; |
1da177e4 | 1963 | |
6758f953 | 1964 | if (fslist) /* add to the specified expiration list */ |
55e700b9 | 1965 | list_add_tail(&newmnt->mnt_expire, fslist); |
6758f953 | 1966 | |
390c6843 | 1967 | up_write(&namespace_sem); |
5b83d2c5 | 1968 | return 0; |
1da177e4 LT |
1969 | |
1970 | unlock: | |
390c6843 | 1971 | up_write(&namespace_sem); |
b3e19d92 | 1972 | mntput_long(newmnt); |
1da177e4 LT |
1973 | return err; |
1974 | } | |
1975 | ||
1976 | EXPORT_SYMBOL_GPL(do_add_mount); | |
1977 | ||
1978 | /* | |
1979 | * process a list of expirable mountpoints with the intent of discarding any | |
1980 | * mountpoints that aren't in use and haven't been touched since last we came | |
1981 | * here | |
1982 | */ | |
1983 | void mark_mounts_for_expiry(struct list_head *mounts) | |
1984 | { | |
1da177e4 LT |
1985 | struct vfsmount *mnt, *next; |
1986 | LIST_HEAD(graveyard); | |
bcc5c7d2 | 1987 | LIST_HEAD(umounts); |
1da177e4 LT |
1988 | |
1989 | if (list_empty(mounts)) | |
1990 | return; | |
1991 | ||
bcc5c7d2 | 1992 | down_write(&namespace_sem); |
99b7db7b | 1993 | br_write_lock(vfsmount_lock); |
1da177e4 LT |
1994 | |
1995 | /* extract from the expiration list every vfsmount that matches the | |
1996 | * following criteria: | |
1997 | * - only referenced by its parent vfsmount | |
1998 | * - still marked for expiry (marked on the last call here; marks are | |
1999 | * cleared by mntput()) | |
2000 | */ | |
55e700b9 | 2001 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 | 2002 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
bcc5c7d2 | 2003 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 2004 | continue; |
55e700b9 | 2005 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 2006 | } |
bcc5c7d2 AV |
2007 | while (!list_empty(&graveyard)) { |
2008 | mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); | |
2009 | touch_mnt_namespace(mnt->mnt_ns); | |
2010 | umount_tree(mnt, 1, &umounts); | |
2011 | } | |
99b7db7b | 2012 | br_write_unlock(vfsmount_lock); |
bcc5c7d2 AV |
2013 | up_write(&namespace_sem); |
2014 | ||
2015 | release_mounts(&umounts); | |
5528f911 TM |
2016 | } |
2017 | ||
2018 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
2019 | ||
2020 | /* | |
2021 | * Ripoff of 'select_parent()' | |
2022 | * | |
2023 | * search the list of submounts for a given mountpoint, and move any | |
2024 | * shrinkable submounts to the 'graveyard' list. | |
2025 | */ | |
2026 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) | |
2027 | { | |
2028 | struct vfsmount *this_parent = parent; | |
2029 | struct list_head *next; | |
2030 | int found = 0; | |
2031 | ||
2032 | repeat: | |
2033 | next = this_parent->mnt_mounts.next; | |
2034 | resume: | |
2035 | while (next != &this_parent->mnt_mounts) { | |
2036 | struct list_head *tmp = next; | |
2037 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); | |
2038 | ||
2039 | next = tmp->next; | |
2040 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) | |
1da177e4 | 2041 | continue; |
5528f911 TM |
2042 | /* |
2043 | * Descend a level if the d_mounts list is non-empty. | |
2044 | */ | |
2045 | if (!list_empty(&mnt->mnt_mounts)) { | |
2046 | this_parent = mnt; | |
2047 | goto repeat; | |
2048 | } | |
1da177e4 | 2049 | |
5528f911 | 2050 | if (!propagate_mount_busy(mnt, 1)) { |
5528f911 TM |
2051 | list_move_tail(&mnt->mnt_expire, graveyard); |
2052 | found++; | |
2053 | } | |
1da177e4 | 2054 | } |
5528f911 TM |
2055 | /* |
2056 | * All done at this level ... ascend and resume the search | |
2057 | */ | |
2058 | if (this_parent != parent) { | |
2059 | next = this_parent->mnt_child.next; | |
2060 | this_parent = this_parent->mnt_parent; | |
2061 | goto resume; | |
2062 | } | |
2063 | return found; | |
2064 | } | |
2065 | ||
2066 | /* | |
2067 | * process a list of expirable mountpoints with the intent of discarding any | |
2068 | * submounts of a specific parent mountpoint | |
99b7db7b NP |
2069 | * |
2070 | * vfsmount_lock must be held for write | |
5528f911 | 2071 | */ |
c35038be | 2072 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) |
5528f911 TM |
2073 | { |
2074 | LIST_HEAD(graveyard); | |
c35038be | 2075 | struct vfsmount *m; |
5528f911 | 2076 | |
5528f911 | 2077 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 2078 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 2079 | while (!list_empty(&graveyard)) { |
c35038be | 2080 | m = list_first_entry(&graveyard, struct vfsmount, |
bcc5c7d2 | 2081 | mnt_expire); |
afef80b3 EB |
2082 | touch_mnt_namespace(m->mnt_ns); |
2083 | umount_tree(m, 1, umounts); | |
bcc5c7d2 AV |
2084 | } |
2085 | } | |
1da177e4 LT |
2086 | } |
2087 | ||
1da177e4 LT |
2088 | /* |
2089 | * Some copy_from_user() implementations do not return the exact number of | |
2090 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
2091 | * Note that this function differs from copy_from_user() in that it will oops | |
2092 | * on bad values of `to', rather than returning a short copy. | |
2093 | */ | |
b58fed8b RP |
2094 | static long exact_copy_from_user(void *to, const void __user * from, |
2095 | unsigned long n) | |
1da177e4 LT |
2096 | { |
2097 | char *t = to; | |
2098 | const char __user *f = from; | |
2099 | char c; | |
2100 | ||
2101 | if (!access_ok(VERIFY_READ, from, n)) | |
2102 | return n; | |
2103 | ||
2104 | while (n) { | |
2105 | if (__get_user(c, f)) { | |
2106 | memset(t, 0, n); | |
2107 | break; | |
2108 | } | |
2109 | *t++ = c; | |
2110 | f++; | |
2111 | n--; | |
2112 | } | |
2113 | return n; | |
2114 | } | |
2115 | ||
b58fed8b | 2116 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
2117 | { |
2118 | int i; | |
2119 | unsigned long page; | |
2120 | unsigned long size; | |
b58fed8b | 2121 | |
1da177e4 LT |
2122 | *where = 0; |
2123 | if (!data) | |
2124 | return 0; | |
2125 | ||
2126 | if (!(page = __get_free_page(GFP_KERNEL))) | |
2127 | return -ENOMEM; | |
2128 | ||
2129 | /* We only care that *some* data at the address the user | |
2130 | * gave us is valid. Just in case, we'll zero | |
2131 | * the remainder of the page. | |
2132 | */ | |
2133 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
2134 | size = TASK_SIZE - (unsigned long)data; | |
2135 | if (size > PAGE_SIZE) | |
2136 | size = PAGE_SIZE; | |
2137 | ||
2138 | i = size - exact_copy_from_user((void *)page, data, size); | |
2139 | if (!i) { | |
b58fed8b | 2140 | free_page(page); |
1da177e4 LT |
2141 | return -EFAULT; |
2142 | } | |
2143 | if (i != PAGE_SIZE) | |
2144 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
2145 | *where = page; | |
2146 | return 0; | |
2147 | } | |
2148 | ||
eca6f534 VN |
2149 | int copy_mount_string(const void __user *data, char **where) |
2150 | { | |
2151 | char *tmp; | |
2152 | ||
2153 | if (!data) { | |
2154 | *where = NULL; | |
2155 | return 0; | |
2156 | } | |
2157 | ||
2158 | tmp = strndup_user(data, PAGE_SIZE); | |
2159 | if (IS_ERR(tmp)) | |
2160 | return PTR_ERR(tmp); | |
2161 | ||
2162 | *where = tmp; | |
2163 | return 0; | |
2164 | } | |
2165 | ||
1da177e4 LT |
2166 | /* |
2167 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
2168 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
2169 | * | |
2170 | * data is a (void *) that can point to any structure up to | |
2171 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
2172 | * information (or be NULL). | |
2173 | * | |
2174 | * Pre-0.97 versions of mount() didn't have a flags word. | |
2175 | * When the flags word was introduced its top half was required | |
2176 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
2177 | * Therefore, if this magic number is present, it carries no information | |
2178 | * and must be discarded. | |
2179 | */ | |
b58fed8b | 2180 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
2181 | unsigned long flags, void *data_page) |
2182 | { | |
2d92ab3c | 2183 | struct path path; |
1da177e4 LT |
2184 | int retval = 0; |
2185 | int mnt_flags = 0; | |
2186 | ||
2187 | /* Discard magic */ | |
2188 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
2189 | flags &= ~MS_MGC_MSK; | |
2190 | ||
2191 | /* Basic sanity checks */ | |
2192 | ||
2193 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
2194 | return -EINVAL; | |
1da177e4 LT |
2195 | |
2196 | if (data_page) | |
2197 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
2198 | ||
a27ab9f2 TH |
2199 | /* ... and get the mountpoint */ |
2200 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); | |
2201 | if (retval) | |
2202 | return retval; | |
2203 | ||
2204 | retval = security_sb_mount(dev_name, &path, | |
2205 | type_page, flags, data_page); | |
2206 | if (retval) | |
2207 | goto dput_out; | |
2208 | ||
613cbe3d AK |
2209 | /* Default to relatime unless overriden */ |
2210 | if (!(flags & MS_NOATIME)) | |
2211 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 2212 | |
1da177e4 LT |
2213 | /* Separate the per-mountpoint flags */ |
2214 | if (flags & MS_NOSUID) | |
2215 | mnt_flags |= MNT_NOSUID; | |
2216 | if (flags & MS_NODEV) | |
2217 | mnt_flags |= MNT_NODEV; | |
2218 | if (flags & MS_NOEXEC) | |
2219 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
2220 | if (flags & MS_NOATIME) |
2221 | mnt_flags |= MNT_NOATIME; | |
2222 | if (flags & MS_NODIRATIME) | |
2223 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
2224 | if (flags & MS_STRICTATIME) |
2225 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
2226 | if (flags & MS_RDONLY) |
2227 | mnt_flags |= MNT_READONLY; | |
fc33a7bb | 2228 | |
7a4dec53 | 2229 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
d0adde57 MG |
2230 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
2231 | MS_STRICTATIME); | |
1da177e4 | 2232 | |
1da177e4 | 2233 | if (flags & MS_REMOUNT) |
2d92ab3c | 2234 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
2235 | data_page); |
2236 | else if (flags & MS_BIND) | |
2d92ab3c | 2237 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 2238 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 2239 | retval = do_change_type(&path, flags); |
1da177e4 | 2240 | else if (flags & MS_MOVE) |
2d92ab3c | 2241 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 2242 | else |
2d92ab3c | 2243 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
2244 | dev_name, data_page); |
2245 | dput_out: | |
2d92ab3c | 2246 | path_put(&path); |
1da177e4 LT |
2247 | return retval; |
2248 | } | |
2249 | ||
cf8d2c11 TM |
2250 | static struct mnt_namespace *alloc_mnt_ns(void) |
2251 | { | |
2252 | struct mnt_namespace *new_ns; | |
2253 | ||
2254 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
2255 | if (!new_ns) | |
2256 | return ERR_PTR(-ENOMEM); | |
2257 | atomic_set(&new_ns->count, 1); | |
2258 | new_ns->root = NULL; | |
2259 | INIT_LIST_HEAD(&new_ns->list); | |
2260 | init_waitqueue_head(&new_ns->poll); | |
2261 | new_ns->event = 0; | |
2262 | return new_ns; | |
2263 | } | |
2264 | ||
741a2951 JD |
2265 | /* |
2266 | * Allocate a new namespace structure and populate it with contents | |
2267 | * copied from the namespace of the passed in task structure. | |
2268 | */ | |
e3222c4e | 2269 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
6b3286ed | 2270 | struct fs_struct *fs) |
1da177e4 | 2271 | { |
6b3286ed | 2272 | struct mnt_namespace *new_ns; |
7f2da1e7 | 2273 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
1da177e4 LT |
2274 | struct vfsmount *p, *q; |
2275 | ||
cf8d2c11 TM |
2276 | new_ns = alloc_mnt_ns(); |
2277 | if (IS_ERR(new_ns)) | |
2278 | return new_ns; | |
1da177e4 | 2279 | |
390c6843 | 2280 | down_write(&namespace_sem); |
1da177e4 | 2281 | /* First pass: copy the tree topology */ |
6b3286ed | 2282 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
9676f0c6 | 2283 | CL_COPY_ALL | CL_EXPIRE); |
1da177e4 | 2284 | if (!new_ns->root) { |
390c6843 | 2285 | up_write(&namespace_sem); |
1da177e4 | 2286 | kfree(new_ns); |
5cc4a034 | 2287 | return ERR_PTR(-ENOMEM); |
1da177e4 | 2288 | } |
99b7db7b | 2289 | br_write_lock(vfsmount_lock); |
1da177e4 | 2290 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
99b7db7b | 2291 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
2292 | |
2293 | /* | |
2294 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2295 | * as belonging to new namespace. We have already acquired a private | |
2296 | * fs_struct, so tsk->fs->lock is not needed. | |
2297 | */ | |
6b3286ed | 2298 | p = mnt_ns->root; |
1da177e4 LT |
2299 | q = new_ns->root; |
2300 | while (p) { | |
6b3286ed | 2301 | q->mnt_ns = new_ns; |
1da177e4 | 2302 | if (fs) { |
6ac08c39 | 2303 | if (p == fs->root.mnt) { |
1da177e4 | 2304 | rootmnt = p; |
b3e19d92 | 2305 | fs->root.mnt = mntget_long(q); |
1da177e4 | 2306 | } |
6ac08c39 | 2307 | if (p == fs->pwd.mnt) { |
1da177e4 | 2308 | pwdmnt = p; |
b3e19d92 | 2309 | fs->pwd.mnt = mntget_long(q); |
1da177e4 | 2310 | } |
1da177e4 | 2311 | } |
6b3286ed | 2312 | p = next_mnt(p, mnt_ns->root); |
1da177e4 LT |
2313 | q = next_mnt(q, new_ns->root); |
2314 | } | |
390c6843 | 2315 | up_write(&namespace_sem); |
1da177e4 | 2316 | |
1da177e4 | 2317 | if (rootmnt) |
b3e19d92 | 2318 | mntput_long(rootmnt); |
1da177e4 | 2319 | if (pwdmnt) |
b3e19d92 | 2320 | mntput_long(pwdmnt); |
1da177e4 | 2321 | |
741a2951 JD |
2322 | return new_ns; |
2323 | } | |
2324 | ||
213dd266 | 2325 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
e3222c4e | 2326 | struct fs_struct *new_fs) |
741a2951 | 2327 | { |
6b3286ed | 2328 | struct mnt_namespace *new_ns; |
741a2951 | 2329 | |
e3222c4e | 2330 | BUG_ON(!ns); |
6b3286ed | 2331 | get_mnt_ns(ns); |
741a2951 JD |
2332 | |
2333 | if (!(flags & CLONE_NEWNS)) | |
e3222c4e | 2334 | return ns; |
741a2951 | 2335 | |
e3222c4e | 2336 | new_ns = dup_mnt_ns(ns, new_fs); |
741a2951 | 2337 | |
6b3286ed | 2338 | put_mnt_ns(ns); |
e3222c4e | 2339 | return new_ns; |
1da177e4 LT |
2340 | } |
2341 | ||
cf8d2c11 TM |
2342 | /** |
2343 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2344 | * @mnt: pointer to the new root filesystem mountpoint | |
2345 | */ | |
a2770d86 | 2346 | struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt) |
cf8d2c11 TM |
2347 | { |
2348 | struct mnt_namespace *new_ns; | |
2349 | ||
2350 | new_ns = alloc_mnt_ns(); | |
2351 | if (!IS_ERR(new_ns)) { | |
2352 | mnt->mnt_ns = new_ns; | |
2353 | new_ns->root = mnt; | |
2354 | list_add(&new_ns->list, &new_ns->root->mnt_list); | |
2355 | } | |
2356 | return new_ns; | |
2357 | } | |
a2770d86 | 2358 | EXPORT_SYMBOL(create_mnt_ns); |
cf8d2c11 | 2359 | |
bdc480e3 HC |
2360 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2361 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2362 | { |
eca6f534 VN |
2363 | int ret; |
2364 | char *kernel_type; | |
2365 | char *kernel_dir; | |
2366 | char *kernel_dev; | |
1da177e4 | 2367 | unsigned long data_page; |
1da177e4 | 2368 | |
eca6f534 VN |
2369 | ret = copy_mount_string(type, &kernel_type); |
2370 | if (ret < 0) | |
2371 | goto out_type; | |
1da177e4 | 2372 | |
eca6f534 VN |
2373 | kernel_dir = getname(dir_name); |
2374 | if (IS_ERR(kernel_dir)) { | |
2375 | ret = PTR_ERR(kernel_dir); | |
2376 | goto out_dir; | |
2377 | } | |
1da177e4 | 2378 | |
eca6f534 VN |
2379 | ret = copy_mount_string(dev_name, &kernel_dev); |
2380 | if (ret < 0) | |
2381 | goto out_dev; | |
1da177e4 | 2382 | |
eca6f534 VN |
2383 | ret = copy_mount_options(data, &data_page); |
2384 | if (ret < 0) | |
2385 | goto out_data; | |
1da177e4 | 2386 | |
eca6f534 VN |
2387 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
2388 | (void *) data_page); | |
1da177e4 | 2389 | |
eca6f534 VN |
2390 | free_page(data_page); |
2391 | out_data: | |
2392 | kfree(kernel_dev); | |
2393 | out_dev: | |
2394 | putname(kernel_dir); | |
2395 | out_dir: | |
2396 | kfree(kernel_type); | |
2397 | out_type: | |
2398 | return ret; | |
1da177e4 LT |
2399 | } |
2400 | ||
1da177e4 LT |
2401 | /* |
2402 | * pivot_root Semantics: | |
2403 | * Moves the root file system of the current process to the directory put_old, | |
2404 | * makes new_root as the new root file system of the current process, and sets | |
2405 | * root/cwd of all processes which had them on the current root to new_root. | |
2406 | * | |
2407 | * Restrictions: | |
2408 | * The new_root and put_old must be directories, and must not be on the | |
2409 | * same file system as the current process root. The put_old must be | |
2410 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2411 | * pointed to by put_old must yield the same directory as new_root. No other | |
2412 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2413 | * | |
4a0d11fa NB |
2414 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2415 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2416 | * in this situation. | |
2417 | * | |
1da177e4 LT |
2418 | * Notes: |
2419 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2420 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2421 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2422 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2423 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2424 | * first. | |
2425 | */ | |
3480b257 HC |
2426 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2427 | const char __user *, put_old) | |
1da177e4 LT |
2428 | { |
2429 | struct vfsmount *tmp; | |
2d8f3038 | 2430 | struct path new, old, parent_path, root_parent, root; |
1da177e4 LT |
2431 | int error; |
2432 | ||
2433 | if (!capable(CAP_SYS_ADMIN)) | |
2434 | return -EPERM; | |
2435 | ||
2d8f3038 | 2436 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2437 | if (error) |
2438 | goto out0; | |
2439 | error = -EINVAL; | |
2d8f3038 | 2440 | if (!check_mnt(new.mnt)) |
1da177e4 LT |
2441 | goto out1; |
2442 | ||
2d8f3038 | 2443 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2444 | if (error) |
2445 | goto out1; | |
2446 | ||
2d8f3038 | 2447 | error = security_sb_pivotroot(&old, &new); |
1da177e4 | 2448 | if (error) { |
2d8f3038 | 2449 | path_put(&old); |
1da177e4 LT |
2450 | goto out1; |
2451 | } | |
2452 | ||
f7ad3c6b | 2453 | get_fs_root(current->fs, &root); |
390c6843 | 2454 | down_write(&namespace_sem); |
2d8f3038 | 2455 | mutex_lock(&old.dentry->d_inode->i_mutex); |
1da177e4 | 2456 | error = -EINVAL; |
2d8f3038 AV |
2457 | if (IS_MNT_SHARED(old.mnt) || |
2458 | IS_MNT_SHARED(new.mnt->mnt_parent) || | |
8c3ee42e | 2459 | IS_MNT_SHARED(root.mnt->mnt_parent)) |
21444403 | 2460 | goto out2; |
8c3ee42e | 2461 | if (!check_mnt(root.mnt)) |
1da177e4 LT |
2462 | goto out2; |
2463 | error = -ENOENT; | |
d83c49f3 | 2464 | if (cant_mount(old.dentry)) |
1da177e4 | 2465 | goto out2; |
f3da392e | 2466 | if (d_unlinked(new.dentry)) |
1da177e4 | 2467 | goto out2; |
f3da392e | 2468 | if (d_unlinked(old.dentry)) |
1da177e4 LT |
2469 | goto out2; |
2470 | error = -EBUSY; | |
2d8f3038 AV |
2471 | if (new.mnt == root.mnt || |
2472 | old.mnt == root.mnt) | |
1da177e4 LT |
2473 | goto out2; /* loop, on the same file system */ |
2474 | error = -EINVAL; | |
8c3ee42e | 2475 | if (root.mnt->mnt_root != root.dentry) |
1da177e4 | 2476 | goto out2; /* not a mountpoint */ |
8c3ee42e | 2477 | if (root.mnt->mnt_parent == root.mnt) |
0bb6fcc1 | 2478 | goto out2; /* not attached */ |
2d8f3038 | 2479 | if (new.mnt->mnt_root != new.dentry) |
1da177e4 | 2480 | goto out2; /* not a mountpoint */ |
2d8f3038 | 2481 | if (new.mnt->mnt_parent == new.mnt) |
0bb6fcc1 | 2482 | goto out2; /* not attached */ |
4ac91378 | 2483 | /* make sure we can reach put_old from new_root */ |
2d8f3038 | 2484 | tmp = old.mnt; |
99b7db7b | 2485 | br_write_lock(vfsmount_lock); |
2d8f3038 | 2486 | if (tmp != new.mnt) { |
1da177e4 LT |
2487 | for (;;) { |
2488 | if (tmp->mnt_parent == tmp) | |
2489 | goto out3; /* already mounted on put_old */ | |
2d8f3038 | 2490 | if (tmp->mnt_parent == new.mnt) |
1da177e4 LT |
2491 | break; |
2492 | tmp = tmp->mnt_parent; | |
2493 | } | |
2d8f3038 | 2494 | if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) |
1da177e4 | 2495 | goto out3; |
2d8f3038 | 2496 | } else if (!is_subdir(old.dentry, new.dentry)) |
1da177e4 | 2497 | goto out3; |
2d8f3038 | 2498 | detach_mnt(new.mnt, &parent_path); |
8c3ee42e | 2499 | detach_mnt(root.mnt, &root_parent); |
4ac91378 | 2500 | /* mount old root on put_old */ |
2d8f3038 | 2501 | attach_mnt(root.mnt, &old); |
4ac91378 | 2502 | /* mount new_root on / */ |
2d8f3038 | 2503 | attach_mnt(new.mnt, &root_parent); |
6b3286ed | 2504 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
99b7db7b | 2505 | br_write_unlock(vfsmount_lock); |
2d8f3038 | 2506 | chroot_fs_refs(&root, &new); |
b3e19d92 | 2507 | |
1da177e4 | 2508 | error = 0; |
1a390689 AV |
2509 | path_put(&root_parent); |
2510 | path_put(&parent_path); | |
1da177e4 | 2511 | out2: |
2d8f3038 | 2512 | mutex_unlock(&old.dentry->d_inode->i_mutex); |
390c6843 | 2513 | up_write(&namespace_sem); |
8c3ee42e | 2514 | path_put(&root); |
2d8f3038 | 2515 | path_put(&old); |
1da177e4 | 2516 | out1: |
2d8f3038 | 2517 | path_put(&new); |
1da177e4 | 2518 | out0: |
1da177e4 LT |
2519 | return error; |
2520 | out3: | |
99b7db7b | 2521 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
2522 | goto out2; |
2523 | } | |
2524 | ||
2525 | static void __init init_mount_tree(void) | |
2526 | { | |
2527 | struct vfsmount *mnt; | |
6b3286ed | 2528 | struct mnt_namespace *ns; |
ac748a09 | 2529 | struct path root; |
1da177e4 LT |
2530 | |
2531 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
2532 | if (IS_ERR(mnt)) | |
2533 | panic("Can't create rootfs"); | |
b3e19d92 | 2534 | |
3b22edc5 TM |
2535 | ns = create_mnt_ns(mnt); |
2536 | if (IS_ERR(ns)) | |
1da177e4 | 2537 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
2538 | |
2539 | init_task.nsproxy->mnt_ns = ns; | |
2540 | get_mnt_ns(ns); | |
2541 | ||
ac748a09 JB |
2542 | root.mnt = ns->root; |
2543 | root.dentry = ns->root->mnt_root; | |
2544 | ||
2545 | set_fs_pwd(current->fs, &root); | |
2546 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
2547 | } |
2548 | ||
74bf17cf | 2549 | void __init mnt_init(void) |
1da177e4 | 2550 | { |
13f14b4d | 2551 | unsigned u; |
15a67dd8 | 2552 | int err; |
1da177e4 | 2553 | |
390c6843 RP |
2554 | init_rwsem(&namespace_sem); |
2555 | ||
1da177e4 | 2556 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
20c2df83 | 2557 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 2558 | |
b58fed8b | 2559 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
2560 | |
2561 | if (!mount_hashtable) | |
2562 | panic("Failed to allocate mount hash table\n"); | |
2563 | ||
13f14b4d ED |
2564 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
2565 | ||
2566 | for (u = 0; u < HASH_SIZE; u++) | |
2567 | INIT_LIST_HEAD(&mount_hashtable[u]); | |
1da177e4 | 2568 | |
99b7db7b NP |
2569 | br_lock_init(vfsmount_lock); |
2570 | ||
15a67dd8 RD |
2571 | err = sysfs_init(); |
2572 | if (err) | |
2573 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 2574 | __func__, err); |
00d26666 GKH |
2575 | fs_kobj = kobject_create_and_add("fs", NULL); |
2576 | if (!fs_kobj) | |
8e24eea7 | 2577 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
2578 | init_rootfs(); |
2579 | init_mount_tree(); | |
2580 | } | |
2581 | ||
616511d0 | 2582 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 2583 | { |
70fbcdf4 | 2584 | LIST_HEAD(umount_list); |
616511d0 | 2585 | |
d498b25a | 2586 | if (!atomic_dec_and_test(&ns->count)) |
616511d0 | 2587 | return; |
390c6843 | 2588 | down_write(&namespace_sem); |
99b7db7b | 2589 | br_write_lock(vfsmount_lock); |
d498b25a | 2590 | umount_tree(ns->root, 0, &umount_list); |
99b7db7b | 2591 | br_write_unlock(vfsmount_lock); |
390c6843 | 2592 | up_write(&namespace_sem); |
70fbcdf4 | 2593 | release_mounts(&umount_list); |
6b3286ed | 2594 | kfree(ns); |
1da177e4 | 2595 | } |
cf8d2c11 | 2596 | EXPORT_SYMBOL(put_mnt_ns); |