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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namespace.c | |
3 | * | |
4 | * (C) Copyright Al Viro 2000, 2001 | |
5 | * Released under GPL v2. | |
6 | * | |
7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. | |
8 | * Heavily rewritten. | |
9 | */ | |
10 | ||
1da177e4 LT |
11 | #include <linux/syscalls.h> |
12 | #include <linux/slab.h> | |
13 | #include <linux/sched.h> | |
99b7db7b NP |
14 | #include <linux/spinlock.h> |
15 | #include <linux/percpu.h> | |
1da177e4 | 16 | #include <linux/init.h> |
15a67dd8 | 17 | #include <linux/kernel.h> |
1da177e4 | 18 | #include <linux/acct.h> |
16f7e0fe | 19 | #include <linux/capability.h> |
3d733633 | 20 | #include <linux/cpumask.h> |
1da177e4 | 21 | #include <linux/module.h> |
f20a9ead | 22 | #include <linux/sysfs.h> |
1da177e4 | 23 | #include <linux/seq_file.h> |
6b3286ed | 24 | #include <linux/mnt_namespace.h> |
1da177e4 | 25 | #include <linux/namei.h> |
b43f3cbd | 26 | #include <linux/nsproxy.h> |
1da177e4 LT |
27 | #include <linux/security.h> |
28 | #include <linux/mount.h> | |
07f3f05c | 29 | #include <linux/ramfs.h> |
13f14b4d | 30 | #include <linux/log2.h> |
73cd49ec | 31 | #include <linux/idr.h> |
5ad4e53b | 32 | #include <linux/fs_struct.h> |
2504c5d6 | 33 | #include <linux/fsnotify.h> |
1da177e4 LT |
34 | #include <asm/uaccess.h> |
35 | #include <asm/unistd.h> | |
07b20889 | 36 | #include "pnode.h" |
948730b0 | 37 | #include "internal.h" |
1da177e4 | 38 | |
13f14b4d ED |
39 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
40 | #define HASH_SIZE (1UL << HASH_SHIFT) | |
41 | ||
5addc5dd | 42 | static int event; |
73cd49ec | 43 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 44 | static DEFINE_IDA(mnt_group_ida); |
99b7db7b | 45 | static DEFINE_SPINLOCK(mnt_id_lock); |
f21f6220 AV |
46 | static int mnt_id_start = 0; |
47 | static int mnt_group_start = 1; | |
1da177e4 | 48 | |
fa3536cc | 49 | static struct list_head *mount_hashtable __read_mostly; |
e18b890b | 50 | static struct kmem_cache *mnt_cache __read_mostly; |
390c6843 | 51 | static struct rw_semaphore namespace_sem; |
1da177e4 | 52 | |
f87fd4c2 | 53 | /* /sys/fs */ |
00d26666 GKH |
54 | struct kobject *fs_kobj; |
55 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 56 | |
99b7db7b NP |
57 | /* |
58 | * vfsmount lock may be taken for read to prevent changes to the | |
59 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
60 | * up the tree. | |
61 | * | |
62 | * It should be taken for write in all cases where the vfsmount | |
63 | * tree or hash is modified or when a vfsmount structure is modified. | |
64 | */ | |
65 | DEFINE_BRLOCK(vfsmount_lock); | |
66 | ||
1da177e4 LT |
67 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
68 | { | |
b58fed8b RP |
69 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
70 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
13f14b4d ED |
71 | tmp = tmp + (tmp >> HASH_SHIFT); |
72 | return tmp & (HASH_SIZE - 1); | |
1da177e4 LT |
73 | } |
74 | ||
3d733633 DH |
75 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
76 | ||
99b7db7b NP |
77 | /* |
78 | * allocation is serialized by namespace_sem, but we need the spinlock to | |
79 | * serialize with freeing. | |
80 | */ | |
b105e270 | 81 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec MS |
82 | { |
83 | int res; | |
84 | ||
85 | retry: | |
86 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); | |
99b7db7b | 87 | spin_lock(&mnt_id_lock); |
b105e270 | 88 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt.mnt_id); |
f21f6220 | 89 | if (!res) |
b105e270 | 90 | mnt_id_start = mnt->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 | ||
b105e270 | 98 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 99 | { |
b105e270 | 100 | int id = mnt->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 | */ | |
4b8b21f4 | 113 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 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, | |
4b8b21f4 | 122 | &mnt->mnt.mnt_group_id); |
f21f6220 | 123 | if (!res) |
4b8b21f4 | 124 | mnt_group_start = mnt->mnt.mnt_group_id + 1; |
f21f6220 AV |
125 | |
126 | return res; | |
719f5d7f MS |
127 | } |
128 | ||
129 | /* | |
130 | * Release a peer group ID | |
131 | */ | |
4b8b21f4 | 132 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 133 | { |
4b8b21f4 | 134 | int id = mnt->mnt.mnt_group_id; |
f21f6220 AV |
135 | ida_remove(&mnt_group_ida, id); |
136 | if (mnt_group_start > id) | |
137 | mnt_group_start = id; | |
4b8b21f4 | 138 | mnt->mnt.mnt_group_id = 0; |
719f5d7f MS |
139 | } |
140 | ||
b3e19d92 NP |
141 | /* |
142 | * vfsmount lock must be held for read | |
143 | */ | |
83adc753 | 144 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
145 | { |
146 | #ifdef CONFIG_SMP | |
68e8a9fe | 147 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
148 | #else |
149 | preempt_disable(); | |
68e8a9fe | 150 | mnt->mnt_count += n; |
b3e19d92 NP |
151 | preempt_enable(); |
152 | #endif | |
153 | } | |
154 | ||
b3e19d92 NP |
155 | /* |
156 | * vfsmount lock must be held for write | |
157 | */ | |
83adc753 | 158 | unsigned int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
159 | { |
160 | #ifdef CONFIG_SMP | |
f03c6599 | 161 | unsigned int count = 0; |
b3e19d92 NP |
162 | int cpu; |
163 | ||
164 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 165 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
166 | } |
167 | ||
168 | return count; | |
169 | #else | |
68e8a9fe | 170 | return mnt->mnt_count; |
b3e19d92 NP |
171 | #endif |
172 | } | |
173 | ||
b105e270 | 174 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 175 | { |
7d6fec45 AV |
176 | struct mount *p = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
177 | if (p) { | |
178 | struct vfsmount *mnt = &p->mnt; | |
73cd49ec MS |
179 | int err; |
180 | ||
b105e270 | 181 | err = mnt_alloc_id(p); |
88b38782 LZ |
182 | if (err) |
183 | goto out_free_cache; | |
184 | ||
185 | if (name) { | |
186 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); | |
187 | if (!mnt->mnt_devname) | |
188 | goto out_free_id; | |
73cd49ec MS |
189 | } |
190 | ||
b3e19d92 | 191 | #ifdef CONFIG_SMP |
68e8a9fe AV |
192 | p->mnt_pcp = alloc_percpu(struct mnt_pcp); |
193 | if (!p->mnt_pcp) | |
b3e19d92 NP |
194 | goto out_free_devname; |
195 | ||
68e8a9fe | 196 | this_cpu_add(p->mnt_pcp->mnt_count, 1); |
b3e19d92 | 197 | #else |
68e8a9fe AV |
198 | p->mnt_count = 1; |
199 | p->mnt_writers = 0; | |
b3e19d92 NP |
200 | #endif |
201 | ||
1b8e5564 | 202 | INIT_LIST_HEAD(&p->mnt_hash); |
6b41d536 AV |
203 | INIT_LIST_HEAD(&p->mnt_child); |
204 | INIT_LIST_HEAD(&p->mnt_mounts); | |
1da177e4 | 205 | INIT_LIST_HEAD(&mnt->mnt_list); |
6776db3d AV |
206 | INIT_LIST_HEAD(&p->mnt_expire); |
207 | INIT_LIST_HEAD(&p->mnt_share); | |
208 | INIT_LIST_HEAD(&p->mnt_slave_list); | |
209 | INIT_LIST_HEAD(&p->mnt_slave); | |
2504c5d6 AG |
210 | #ifdef CONFIG_FSNOTIFY |
211 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); | |
d3ef3d73 | 212 | #endif |
1da177e4 | 213 | } |
b105e270 | 214 | return p; |
88b38782 | 215 | |
d3ef3d73 | 216 | #ifdef CONFIG_SMP |
217 | out_free_devname: | |
7d6fec45 | 218 | kfree(p->mnt.mnt_devname); |
d3ef3d73 | 219 | #endif |
88b38782 | 220 | out_free_id: |
b105e270 | 221 | mnt_free_id(p); |
88b38782 | 222 | out_free_cache: |
7d6fec45 | 223 | kmem_cache_free(mnt_cache, p); |
88b38782 | 224 | return NULL; |
1da177e4 LT |
225 | } |
226 | ||
3d733633 DH |
227 | /* |
228 | * Most r/o checks on a fs are for operations that take | |
229 | * discrete amounts of time, like a write() or unlink(). | |
230 | * We must keep track of when those operations start | |
231 | * (for permission checks) and when they end, so that | |
232 | * we can determine when writes are able to occur to | |
233 | * a filesystem. | |
234 | */ | |
235 | /* | |
236 | * __mnt_is_readonly: check whether a mount is read-only | |
237 | * @mnt: the mount to check for its write status | |
238 | * | |
239 | * This shouldn't be used directly ouside of the VFS. | |
240 | * It does not guarantee that the filesystem will stay | |
241 | * r/w, just that it is right *now*. This can not and | |
242 | * should not be used in place of IS_RDONLY(inode). | |
243 | * mnt_want/drop_write() will _keep_ the filesystem | |
244 | * r/w. | |
245 | */ | |
246 | int __mnt_is_readonly(struct vfsmount *mnt) | |
247 | { | |
2e4b7fcd DH |
248 | if (mnt->mnt_flags & MNT_READONLY) |
249 | return 1; | |
250 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
251 | return 1; | |
252 | return 0; | |
3d733633 DH |
253 | } |
254 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
255 | ||
83adc753 | 256 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 | 257 | { |
258 | #ifdef CONFIG_SMP | |
68e8a9fe | 259 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 260 | #else |
68e8a9fe | 261 | mnt->mnt_writers++; |
d3ef3d73 | 262 | #endif |
263 | } | |
3d733633 | 264 | |
83adc753 | 265 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 266 | { |
d3ef3d73 | 267 | #ifdef CONFIG_SMP |
68e8a9fe | 268 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 269 | #else |
68e8a9fe | 270 | mnt->mnt_writers--; |
d3ef3d73 | 271 | #endif |
3d733633 | 272 | } |
3d733633 | 273 | |
83adc753 | 274 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 275 | { |
d3ef3d73 | 276 | #ifdef CONFIG_SMP |
277 | unsigned int count = 0; | |
3d733633 | 278 | int cpu; |
3d733633 DH |
279 | |
280 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 281 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 282 | } |
3d733633 | 283 | |
d3ef3d73 | 284 | return count; |
285 | #else | |
286 | return mnt->mnt_writers; | |
287 | #endif | |
3d733633 DH |
288 | } |
289 | ||
8366025e DH |
290 | /* |
291 | * Most r/o checks on a fs are for operations that take | |
292 | * discrete amounts of time, like a write() or unlink(). | |
293 | * We must keep track of when those operations start | |
294 | * (for permission checks) and when they end, so that | |
295 | * we can determine when writes are able to occur to | |
296 | * a filesystem. | |
297 | */ | |
298 | /** | |
299 | * mnt_want_write - get write access to a mount | |
83adc753 | 300 | * @m: the mount on which to take a write |
8366025e DH |
301 | * |
302 | * This tells the low-level filesystem that a write is | |
303 | * about to be performed to it, and makes sure that | |
304 | * writes are allowed before returning success. When | |
305 | * the write operation is finished, mnt_drop_write() | |
306 | * must be called. This is effectively a refcount. | |
307 | */ | |
83adc753 | 308 | int mnt_want_write(struct vfsmount *m) |
8366025e | 309 | { |
83adc753 | 310 | struct mount *mnt = real_mount(m); |
3d733633 | 311 | int ret = 0; |
3d733633 | 312 | |
d3ef3d73 | 313 | preempt_disable(); |
c6653a83 | 314 | mnt_inc_writers(mnt); |
d3ef3d73 | 315 | /* |
c6653a83 | 316 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 | 317 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
318 | * incremented count after it has set MNT_WRITE_HOLD. | |
319 | */ | |
320 | smp_mb(); | |
83adc753 | 321 | while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
d3ef3d73 | 322 | cpu_relax(); |
323 | /* | |
324 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
325 | * be set to match its requirements. So we must not load that until | |
326 | * MNT_WRITE_HOLD is cleared. | |
327 | */ | |
328 | smp_rmb(); | |
83adc753 | 329 | if (__mnt_is_readonly(m)) { |
c6653a83 | 330 | mnt_dec_writers(mnt); |
3d733633 DH |
331 | ret = -EROFS; |
332 | goto out; | |
333 | } | |
3d733633 | 334 | out: |
d3ef3d73 | 335 | preempt_enable(); |
3d733633 | 336 | return ret; |
8366025e DH |
337 | } |
338 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
339 | ||
96029c4e | 340 | /** |
341 | * mnt_clone_write - get write access to a mount | |
342 | * @mnt: the mount on which to take a write | |
343 | * | |
344 | * This is effectively like mnt_want_write, except | |
345 | * it must only be used to take an extra write reference | |
346 | * on a mountpoint that we already know has a write reference | |
347 | * on it. This allows some optimisation. | |
348 | * | |
349 | * After finished, mnt_drop_write must be called as usual to | |
350 | * drop the reference. | |
351 | */ | |
352 | int mnt_clone_write(struct vfsmount *mnt) | |
353 | { | |
354 | /* superblock may be r/o */ | |
355 | if (__mnt_is_readonly(mnt)) | |
356 | return -EROFS; | |
357 | preempt_disable(); | |
83adc753 | 358 | mnt_inc_writers(real_mount(mnt)); |
96029c4e | 359 | preempt_enable(); |
360 | return 0; | |
361 | } | |
362 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
363 | ||
364 | /** | |
365 | * mnt_want_write_file - get write access to a file's mount | |
366 | * @file: the file who's mount on which to take a write | |
367 | * | |
368 | * This is like mnt_want_write, but it takes a file and can | |
369 | * do some optimisations if the file is open for write already | |
370 | */ | |
371 | int mnt_want_write_file(struct file *file) | |
372 | { | |
2d8dd38a OH |
373 | struct inode *inode = file->f_dentry->d_inode; |
374 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) | |
96029c4e | 375 | return mnt_want_write(file->f_path.mnt); |
376 | else | |
377 | return mnt_clone_write(file->f_path.mnt); | |
378 | } | |
379 | EXPORT_SYMBOL_GPL(mnt_want_write_file); | |
380 | ||
8366025e DH |
381 | /** |
382 | * mnt_drop_write - give up write access to a mount | |
383 | * @mnt: the mount on which to give up write access | |
384 | * | |
385 | * Tells the low-level filesystem that we are done | |
386 | * performing writes to it. Must be matched with | |
387 | * mnt_want_write() call above. | |
388 | */ | |
389 | void mnt_drop_write(struct vfsmount *mnt) | |
390 | { | |
d3ef3d73 | 391 | preempt_disable(); |
83adc753 | 392 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 393 | preempt_enable(); |
8366025e DH |
394 | } |
395 | EXPORT_SYMBOL_GPL(mnt_drop_write); | |
396 | ||
2a79f17e AV |
397 | void mnt_drop_write_file(struct file *file) |
398 | { | |
399 | mnt_drop_write(file->f_path.mnt); | |
400 | } | |
401 | EXPORT_SYMBOL(mnt_drop_write_file); | |
402 | ||
83adc753 | 403 | static int mnt_make_readonly(struct mount *mnt) |
8366025e | 404 | { |
3d733633 DH |
405 | int ret = 0; |
406 | ||
99b7db7b | 407 | br_write_lock(vfsmount_lock); |
83adc753 | 408 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 409 | /* |
d3ef3d73 | 410 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
411 | * should be visible before we do. | |
3d733633 | 412 | */ |
d3ef3d73 | 413 | smp_mb(); |
414 | ||
3d733633 | 415 | /* |
d3ef3d73 | 416 | * With writers on hold, if this value is zero, then there are |
417 | * definitely no active writers (although held writers may subsequently | |
418 | * increment the count, they'll have to wait, and decrement it after | |
419 | * seeing MNT_READONLY). | |
420 | * | |
421 | * It is OK to have counter incremented on one CPU and decremented on | |
422 | * another: the sum will add up correctly. The danger would be when we | |
423 | * sum up each counter, if we read a counter before it is incremented, | |
424 | * but then read another CPU's count which it has been subsequently | |
425 | * decremented from -- we would see more decrements than we should. | |
426 | * MNT_WRITE_HOLD protects against this scenario, because | |
427 | * mnt_want_write first increments count, then smp_mb, then spins on | |
428 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
429 | * we're counting up here. | |
3d733633 | 430 | */ |
c6653a83 | 431 | if (mnt_get_writers(mnt) > 0) |
d3ef3d73 | 432 | ret = -EBUSY; |
433 | else | |
83adc753 | 434 | mnt->mnt.mnt_flags |= MNT_READONLY; |
d3ef3d73 | 435 | /* |
436 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
437 | * that become unheld will see MNT_READONLY. | |
438 | */ | |
439 | smp_wmb(); | |
83adc753 | 440 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
99b7db7b | 441 | br_write_unlock(vfsmount_lock); |
3d733633 | 442 | return ret; |
8366025e | 443 | } |
8366025e | 444 | |
83adc753 | 445 | static void __mnt_unmake_readonly(struct mount *mnt) |
2e4b7fcd | 446 | { |
99b7db7b | 447 | br_write_lock(vfsmount_lock); |
83adc753 | 448 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
99b7db7b | 449 | br_write_unlock(vfsmount_lock); |
2e4b7fcd DH |
450 | } |
451 | ||
b105e270 | 452 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 453 | { |
b105e270 | 454 | kfree(mnt->mnt.mnt_devname); |
73cd49ec | 455 | mnt_free_id(mnt); |
d3ef3d73 | 456 | #ifdef CONFIG_SMP |
68e8a9fe | 457 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 458 | #endif |
b105e270 | 459 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
460 | } |
461 | ||
462 | /* | |
a05964f3 RP |
463 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
464 | * @dir. If @dir is set return the first mount else return the last mount. | |
99b7db7b | 465 | * vfsmount_lock must be held for read or write. |
1da177e4 | 466 | */ |
c7105365 | 467 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
a05964f3 | 468 | int dir) |
1da177e4 | 469 | { |
b58fed8b RP |
470 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
471 | struct list_head *tmp = head; | |
c7105365 | 472 | struct mount *p, *found = NULL; |
1da177e4 | 473 | |
1da177e4 | 474 | for (;;) { |
a05964f3 | 475 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
476 | p = NULL; |
477 | if (tmp == head) | |
478 | break; | |
1b8e5564 | 479 | p = list_entry(tmp, struct mount, mnt_hash); |
a73324da | 480 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) { |
a05964f3 | 481 | found = p; |
1da177e4 LT |
482 | break; |
483 | } | |
484 | } | |
1da177e4 LT |
485 | return found; |
486 | } | |
487 | ||
a05964f3 RP |
488 | /* |
489 | * lookup_mnt increments the ref count before returning | |
490 | * the vfsmount struct. | |
491 | */ | |
1c755af4 | 492 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 | 493 | { |
c7105365 | 494 | struct mount *child_mnt; |
99b7db7b NP |
495 | |
496 | br_read_lock(vfsmount_lock); | |
c7105365 AV |
497 | child_mnt = __lookup_mnt(path->mnt, path->dentry, 1); |
498 | if (child_mnt) { | |
499 | mnt_add_count(child_mnt, 1); | |
500 | br_read_unlock(vfsmount_lock); | |
501 | return &child_mnt->mnt; | |
502 | } else { | |
503 | br_read_unlock(vfsmount_lock); | |
504 | return NULL; | |
505 | } | |
a05964f3 RP |
506 | } |
507 | ||
1da177e4 LT |
508 | static inline int check_mnt(struct vfsmount *mnt) |
509 | { | |
6b3286ed | 510 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
511 | } |
512 | ||
99b7db7b NP |
513 | /* |
514 | * vfsmount lock must be held for write | |
515 | */ | |
6b3286ed | 516 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
517 | { |
518 | if (ns) { | |
519 | ns->event = ++event; | |
520 | wake_up_interruptible(&ns->poll); | |
521 | } | |
522 | } | |
523 | ||
99b7db7b NP |
524 | /* |
525 | * vfsmount lock must be held for write | |
526 | */ | |
6b3286ed | 527 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
528 | { |
529 | if (ns && ns->event != event) { | |
530 | ns->event = event; | |
531 | wake_up_interruptible(&ns->poll); | |
532 | } | |
533 | } | |
534 | ||
5f57cbcc NP |
535 | /* |
536 | * Clear dentry's mounted state if it has no remaining mounts. | |
537 | * vfsmount_lock must be held for write. | |
538 | */ | |
aa0a4cf0 | 539 | static void dentry_reset_mounted(struct dentry *dentry) |
5f57cbcc NP |
540 | { |
541 | unsigned u; | |
542 | ||
543 | for (u = 0; u < HASH_SIZE; u++) { | |
d5e50f74 | 544 | struct mount *p; |
5f57cbcc | 545 | |
1b8e5564 | 546 | list_for_each_entry(p, &mount_hashtable[u], mnt_hash) { |
a73324da | 547 | if (p->mnt_mountpoint == dentry) |
5f57cbcc NP |
548 | return; |
549 | } | |
550 | } | |
551 | spin_lock(&dentry->d_lock); | |
552 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
553 | spin_unlock(&dentry->d_lock); | |
554 | } | |
555 | ||
99b7db7b NP |
556 | /* |
557 | * vfsmount lock must be held for write | |
558 | */ | |
419148da AV |
559 | static void detach_mnt(struct mount *mnt, struct path *old_path) |
560 | { | |
a73324da | 561 | old_path->dentry = mnt->mnt_mountpoint; |
0714a533 AV |
562 | old_path->mnt = &mnt->mnt_parent->mnt; |
563 | mnt->mnt_parent = mnt; | |
a73324da | 564 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 565 | list_del_init(&mnt->mnt_child); |
1b8e5564 | 566 | list_del_init(&mnt->mnt_hash); |
aa0a4cf0 | 567 | dentry_reset_mounted(old_path->dentry); |
1da177e4 LT |
568 | } |
569 | ||
99b7db7b NP |
570 | /* |
571 | * vfsmount lock must be held for write | |
572 | */ | |
14cf1fa8 | 573 | void mnt_set_mountpoint(struct mount *mnt, struct dentry *dentry, |
44d964d6 | 574 | struct mount *child_mnt) |
b90fa9ae | 575 | { |
14cf1fa8 | 576 | child_mnt->mnt_parent = real_mount(mntget(&mnt->mnt)); |
a73324da | 577 | child_mnt->mnt_mountpoint = dget(dentry); |
5f57cbcc NP |
578 | spin_lock(&dentry->d_lock); |
579 | dentry->d_flags |= DCACHE_MOUNTED; | |
580 | spin_unlock(&dentry->d_lock); | |
b90fa9ae RP |
581 | } |
582 | ||
99b7db7b NP |
583 | /* |
584 | * vfsmount lock must be held for write | |
585 | */ | |
419148da | 586 | static void attach_mnt(struct mount *mnt, struct path *path) |
1da177e4 | 587 | { |
14cf1fa8 | 588 | mnt_set_mountpoint(real_mount(path->mnt), path->dentry, mnt); |
1b8e5564 | 589 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
1a390689 | 590 | hash(path->mnt, path->dentry)); |
6b41d536 | 591 | list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts); |
b90fa9ae RP |
592 | } |
593 | ||
83adc753 | 594 | static inline void __mnt_make_longterm(struct mount *mnt) |
7e3d0eb0 AV |
595 | { |
596 | #ifdef CONFIG_SMP | |
68e8a9fe | 597 | atomic_inc(&mnt->mnt_longterm); |
7e3d0eb0 AV |
598 | #endif |
599 | } | |
600 | ||
601 | /* needs vfsmount lock for write */ | |
83adc753 | 602 | static inline void __mnt_make_shortterm(struct mount *mnt) |
7e3d0eb0 AV |
603 | { |
604 | #ifdef CONFIG_SMP | |
68e8a9fe | 605 | atomic_dec(&mnt->mnt_longterm); |
7e3d0eb0 AV |
606 | #endif |
607 | } | |
608 | ||
b90fa9ae | 609 | /* |
99b7db7b | 610 | * vfsmount lock must be held for write |
b90fa9ae | 611 | */ |
4b2619a5 | 612 | static void commit_tree(struct mount *mnt) |
b90fa9ae | 613 | { |
0714a533 | 614 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 615 | struct mount *m; |
b90fa9ae | 616 | LIST_HEAD(head); |
0714a533 | 617 | struct mnt_namespace *n = parent->mnt.mnt_ns; |
b90fa9ae | 618 | |
0714a533 | 619 | BUG_ON(parent == mnt); |
b90fa9ae | 620 | |
4b2619a5 | 621 | list_add_tail(&head, &mnt->mnt.mnt_list); |
83adc753 AV |
622 | list_for_each_entry(m, &head, mnt.mnt_list) { |
623 | m->mnt.mnt_ns = n; | |
7e3d0eb0 | 624 | __mnt_make_longterm(m); |
f03c6599 AV |
625 | } |
626 | ||
b90fa9ae RP |
627 | list_splice(&head, n->list.prev); |
628 | ||
1b8e5564 | 629 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
a73324da | 630 | hash(&parent->mnt, mnt->mnt_mountpoint)); |
6b41d536 | 631 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
6b3286ed | 632 | touch_mnt_namespace(n); |
1da177e4 LT |
633 | } |
634 | ||
315fc83e | 635 | static struct mount *next_mnt(struct mount *p, struct vfsmount *root) |
1da177e4 | 636 | { |
6b41d536 AV |
637 | struct list_head *next = p->mnt_mounts.next; |
638 | if (next == &p->mnt_mounts) { | |
1da177e4 | 639 | while (1) { |
315fc83e | 640 | if (&p->mnt == root) |
1da177e4 | 641 | return NULL; |
6b41d536 AV |
642 | next = p->mnt_child.next; |
643 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 644 | break; |
0714a533 | 645 | p = p->mnt_parent; |
1da177e4 LT |
646 | } |
647 | } | |
6b41d536 | 648 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
649 | } |
650 | ||
315fc83e | 651 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 652 | { |
6b41d536 AV |
653 | struct list_head *prev = p->mnt_mounts.prev; |
654 | while (prev != &p->mnt_mounts) { | |
655 | p = list_entry(prev, struct mount, mnt_child); | |
656 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
657 | } |
658 | return p; | |
659 | } | |
660 | ||
9d412a43 AV |
661 | struct vfsmount * |
662 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) | |
663 | { | |
b105e270 | 664 | struct mount *mnt; |
9d412a43 AV |
665 | struct dentry *root; |
666 | ||
667 | if (!type) | |
668 | return ERR_PTR(-ENODEV); | |
669 | ||
670 | mnt = alloc_vfsmnt(name); | |
671 | if (!mnt) | |
672 | return ERR_PTR(-ENOMEM); | |
673 | ||
674 | if (flags & MS_KERNMOUNT) | |
b105e270 | 675 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 AV |
676 | |
677 | root = mount_fs(type, flags, name, data); | |
678 | if (IS_ERR(root)) { | |
679 | free_vfsmnt(mnt); | |
680 | return ERR_CAST(root); | |
681 | } | |
682 | ||
b105e270 AV |
683 | mnt->mnt.mnt_root = root; |
684 | mnt->mnt.mnt_sb = root->d_sb; | |
a73324da | 685 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
0714a533 | 686 | mnt->mnt_parent = mnt; |
b105e270 | 687 | return &mnt->mnt; |
9d412a43 AV |
688 | } |
689 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
690 | ||
87129cc0 | 691 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 692 | int flag) |
1da177e4 | 693 | { |
87129cc0 AV |
694 | struct super_block *sb = old->mnt.mnt_sb; |
695 | struct mount *mnt = alloc_vfsmnt(old->mnt.mnt_devname); | |
1da177e4 LT |
696 | |
697 | if (mnt) { | |
719f5d7f | 698 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
b105e270 | 699 | mnt->mnt.mnt_group_id = 0; /* not a peer of original */ |
719f5d7f | 700 | else |
87129cc0 | 701 | mnt->mnt.mnt_group_id = old->mnt.mnt_group_id; |
719f5d7f | 702 | |
b105e270 AV |
703 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt.mnt_group_id) { |
704 | int err = mnt_alloc_group_id(mnt); | |
719f5d7f MS |
705 | if (err) |
706 | goto out_free; | |
707 | } | |
708 | ||
87129cc0 | 709 | mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; |
1da177e4 | 710 | atomic_inc(&sb->s_active); |
b105e270 AV |
711 | mnt->mnt.mnt_sb = sb; |
712 | mnt->mnt.mnt_root = dget(root); | |
a73324da | 713 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
0714a533 | 714 | mnt->mnt_parent = mnt; |
b90fa9ae | 715 | |
5afe0022 | 716 | if (flag & CL_SLAVE) { |
6776db3d | 717 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
32301920 | 718 | mnt->mnt_master = old; |
b105e270 | 719 | CLEAR_MNT_SHARED(&mnt->mnt); |
8aec0809 | 720 | } else if (!(flag & CL_PRIVATE)) { |
87129cc0 | 721 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(&old->mnt)) |
6776db3d | 722 | list_add(&mnt->mnt_share, &old->mnt_share); |
d10e8def | 723 | if (IS_MNT_SLAVE(old)) |
6776db3d | 724 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
d10e8def | 725 | mnt->mnt_master = old->mnt_master; |
5afe0022 | 726 | } |
b90fa9ae | 727 | if (flag & CL_MAKE_SHARED) |
0f0afb1d | 728 | set_mnt_shared(mnt); |
1da177e4 LT |
729 | |
730 | /* stick the duplicate mount on the same expiry list | |
731 | * as the original if that was on one */ | |
36341f64 | 732 | if (flag & CL_EXPIRE) { |
6776db3d AV |
733 | if (!list_empty(&old->mnt_expire)) |
734 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
36341f64 | 735 | } |
1da177e4 | 736 | } |
cb338d06 | 737 | return mnt; |
719f5d7f MS |
738 | |
739 | out_free: | |
740 | free_vfsmnt(mnt); | |
741 | return NULL; | |
1da177e4 LT |
742 | } |
743 | ||
83adc753 | 744 | static inline void mntfree(struct mount *mnt) |
1da177e4 | 745 | { |
83adc753 AV |
746 | struct vfsmount *m = &mnt->mnt; |
747 | struct super_block *sb = m->mnt_sb; | |
b3e19d92 | 748 | |
3d733633 DH |
749 | /* |
750 | * This probably indicates that somebody messed | |
751 | * up a mnt_want/drop_write() pair. If this | |
752 | * happens, the filesystem was probably unable | |
753 | * to make r/w->r/o transitions. | |
754 | */ | |
d3ef3d73 | 755 | /* |
b3e19d92 NP |
756 | * The locking used to deal with mnt_count decrement provides barriers, |
757 | * so mnt_get_writers() below is safe. | |
d3ef3d73 | 758 | */ |
c6653a83 | 759 | WARN_ON(mnt_get_writers(mnt)); |
83adc753 AV |
760 | fsnotify_vfsmount_delete(m); |
761 | dput(m->mnt_root); | |
762 | free_vfsmnt(mnt); | |
1da177e4 LT |
763 | deactivate_super(sb); |
764 | } | |
765 | ||
900148dc | 766 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 767 | { |
b3e19d92 | 768 | put_again: |
f03c6599 AV |
769 | #ifdef CONFIG_SMP |
770 | br_read_lock(vfsmount_lock); | |
68e8a9fe | 771 | if (likely(atomic_read(&mnt->mnt_longterm))) { |
aa9c0e07 | 772 | mnt_add_count(mnt, -1); |
b3e19d92 | 773 | br_read_unlock(vfsmount_lock); |
f03c6599 | 774 | return; |
b3e19d92 | 775 | } |
f03c6599 | 776 | br_read_unlock(vfsmount_lock); |
b3e19d92 | 777 | |
99b7db7b | 778 | br_write_lock(vfsmount_lock); |
aa9c0e07 | 779 | mnt_add_count(mnt, -1); |
b3e19d92 | 780 | if (mnt_get_count(mnt)) { |
99b7db7b NP |
781 | br_write_unlock(vfsmount_lock); |
782 | return; | |
783 | } | |
b3e19d92 | 784 | #else |
aa9c0e07 | 785 | mnt_add_count(mnt, -1); |
b3e19d92 | 786 | if (likely(mnt_get_count(mnt))) |
99b7db7b | 787 | return; |
b3e19d92 | 788 | br_write_lock(vfsmount_lock); |
f03c6599 | 789 | #endif |
83adc753 AV |
790 | if (unlikely(mnt->mnt.mnt_pinned)) { |
791 | mnt_add_count(mnt, mnt->mnt.mnt_pinned + 1); | |
792 | mnt->mnt.mnt_pinned = 0; | |
b3e19d92 | 793 | br_write_unlock(vfsmount_lock); |
900148dc | 794 | acct_auto_close_mnt(&mnt->mnt); |
b3e19d92 | 795 | goto put_again; |
7b7b1ace | 796 | } |
99b7db7b | 797 | br_write_unlock(vfsmount_lock); |
b3e19d92 NP |
798 | mntfree(mnt); |
799 | } | |
b3e19d92 NP |
800 | |
801 | void mntput(struct vfsmount *mnt) | |
802 | { | |
803 | if (mnt) { | |
804 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ | |
805 | if (unlikely(mnt->mnt_expiry_mark)) | |
806 | mnt->mnt_expiry_mark = 0; | |
900148dc | 807 | mntput_no_expire(real_mount(mnt)); |
b3e19d92 NP |
808 | } |
809 | } | |
810 | EXPORT_SYMBOL(mntput); | |
811 | ||
812 | struct vfsmount *mntget(struct vfsmount *mnt) | |
813 | { | |
814 | if (mnt) | |
83adc753 | 815 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
816 | return mnt; |
817 | } | |
818 | EXPORT_SYMBOL(mntget); | |
819 | ||
7b7b1ace AV |
820 | void mnt_pin(struct vfsmount *mnt) |
821 | { | |
99b7db7b | 822 | br_write_lock(vfsmount_lock); |
7b7b1ace | 823 | mnt->mnt_pinned++; |
99b7db7b | 824 | br_write_unlock(vfsmount_lock); |
7b7b1ace | 825 | } |
7b7b1ace AV |
826 | EXPORT_SYMBOL(mnt_pin); |
827 | ||
828 | void mnt_unpin(struct vfsmount *mnt) | |
829 | { | |
99b7db7b | 830 | br_write_lock(vfsmount_lock); |
7b7b1ace | 831 | if (mnt->mnt_pinned) { |
83adc753 | 832 | mnt_add_count(real_mount(mnt), 1); |
7b7b1ace AV |
833 | mnt->mnt_pinned--; |
834 | } | |
99b7db7b | 835 | br_write_unlock(vfsmount_lock); |
7b7b1ace | 836 | } |
7b7b1ace | 837 | EXPORT_SYMBOL(mnt_unpin); |
1da177e4 | 838 | |
b3b304a2 MS |
839 | static inline void mangle(struct seq_file *m, const char *s) |
840 | { | |
841 | seq_escape(m, s, " \t\n\\"); | |
842 | } | |
843 | ||
844 | /* | |
845 | * Simple .show_options callback for filesystems which don't want to | |
846 | * implement more complex mount option showing. | |
847 | * | |
848 | * See also save_mount_options(). | |
849 | */ | |
850 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) | |
851 | { | |
2a32cebd AV |
852 | const char *options; |
853 | ||
854 | rcu_read_lock(); | |
855 | options = rcu_dereference(mnt->mnt_sb->s_options); | |
b3b304a2 MS |
856 | |
857 | if (options != NULL && options[0]) { | |
858 | seq_putc(m, ','); | |
859 | mangle(m, options); | |
860 | } | |
2a32cebd | 861 | rcu_read_unlock(); |
b3b304a2 MS |
862 | |
863 | return 0; | |
864 | } | |
865 | EXPORT_SYMBOL(generic_show_options); | |
866 | ||
867 | /* | |
868 | * If filesystem uses generic_show_options(), this function should be | |
869 | * called from the fill_super() callback. | |
870 | * | |
871 | * The .remount_fs callback usually needs to be handled in a special | |
872 | * way, to make sure, that previous options are not overwritten if the | |
873 | * remount fails. | |
874 | * | |
875 | * Also note, that if the filesystem's .remount_fs function doesn't | |
876 | * reset all options to their default value, but changes only newly | |
877 | * given options, then the displayed options will not reflect reality | |
878 | * any more. | |
879 | */ | |
880 | void save_mount_options(struct super_block *sb, char *options) | |
881 | { | |
2a32cebd AV |
882 | BUG_ON(sb->s_options); |
883 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
884 | } |
885 | EXPORT_SYMBOL(save_mount_options); | |
886 | ||
2a32cebd AV |
887 | void replace_mount_options(struct super_block *sb, char *options) |
888 | { | |
889 | char *old = sb->s_options; | |
890 | rcu_assign_pointer(sb->s_options, options); | |
891 | if (old) { | |
892 | synchronize_rcu(); | |
893 | kfree(old); | |
894 | } | |
895 | } | |
896 | EXPORT_SYMBOL(replace_mount_options); | |
897 | ||
a1a2c409 | 898 | #ifdef CONFIG_PROC_FS |
1da177e4 LT |
899 | /* iterator */ |
900 | static void *m_start(struct seq_file *m, loff_t *pos) | |
901 | { | |
a1a2c409 | 902 | struct proc_mounts *p = m->private; |
1da177e4 | 903 | |
390c6843 | 904 | down_read(&namespace_sem); |
a1a2c409 | 905 | return seq_list_start(&p->ns->list, *pos); |
1da177e4 LT |
906 | } |
907 | ||
908 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
909 | { | |
a1a2c409 | 910 | struct proc_mounts *p = m->private; |
b0765fb8 | 911 | |
a1a2c409 | 912 | return seq_list_next(v, &p->ns->list, pos); |
1da177e4 LT |
913 | } |
914 | ||
915 | static void m_stop(struct seq_file *m, void *v) | |
916 | { | |
390c6843 | 917 | up_read(&namespace_sem); |
1da177e4 LT |
918 | } |
919 | ||
9f5596af AV |
920 | int mnt_had_events(struct proc_mounts *p) |
921 | { | |
922 | struct mnt_namespace *ns = p->ns; | |
923 | int res = 0; | |
924 | ||
99b7db7b | 925 | br_read_lock(vfsmount_lock); |
f1514638 KS |
926 | if (p->m.poll_event != ns->event) { |
927 | p->m.poll_event = ns->event; | |
9f5596af AV |
928 | res = 1; |
929 | } | |
99b7db7b | 930 | br_read_unlock(vfsmount_lock); |
9f5596af AV |
931 | |
932 | return res; | |
933 | } | |
934 | ||
2d4d4864 RP |
935 | struct proc_fs_info { |
936 | int flag; | |
937 | const char *str; | |
938 | }; | |
939 | ||
2069f457 | 940 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
1da177e4 | 941 | { |
2d4d4864 | 942 | static const struct proc_fs_info fs_info[] = { |
1da177e4 LT |
943 | { MS_SYNCHRONOUS, ",sync" }, |
944 | { MS_DIRSYNC, ",dirsync" }, | |
945 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
946 | { 0, NULL } |
947 | }; | |
2d4d4864 RP |
948 | const struct proc_fs_info *fs_infop; |
949 | ||
950 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
951 | if (sb->s_flags & fs_infop->flag) | |
952 | seq_puts(m, fs_infop->str); | |
953 | } | |
2069f457 EP |
954 | |
955 | return security_sb_show_options(m, sb); | |
2d4d4864 RP |
956 | } |
957 | ||
958 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) | |
959 | { | |
960 | static const struct proc_fs_info mnt_info[] = { | |
1da177e4 LT |
961 | { MNT_NOSUID, ",nosuid" }, |
962 | { MNT_NODEV, ",nodev" }, | |
963 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
964 | { MNT_NOATIME, ",noatime" }, |
965 | { MNT_NODIRATIME, ",nodiratime" }, | |
47ae32d6 | 966 | { MNT_RELATIME, ",relatime" }, |
1da177e4 LT |
967 | { 0, NULL } |
968 | }; | |
2d4d4864 RP |
969 | const struct proc_fs_info *fs_infop; |
970 | ||
971 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
972 | if (mnt->mnt_flags & fs_infop->flag) | |
973 | seq_puts(m, fs_infop->str); | |
974 | } | |
975 | } | |
976 | ||
977 | static void show_type(struct seq_file *m, struct super_block *sb) | |
978 | { | |
979 | mangle(m, sb->s_type->name); | |
980 | if (sb->s_subtype && sb->s_subtype[0]) { | |
981 | seq_putc(m, '.'); | |
982 | mangle(m, sb->s_subtype); | |
983 | } | |
984 | } | |
985 | ||
986 | static int show_vfsmnt(struct seq_file *m, void *v) | |
987 | { | |
988 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
989 | int err = 0; | |
c32c2f63 | 990 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
1da177e4 | 991 | |
c7f404b4 AV |
992 | if (mnt->mnt_sb->s_op->show_devname) { |
993 | err = mnt->mnt_sb->s_op->show_devname(m, mnt); | |
994 | if (err) | |
995 | goto out; | |
996 | } else { | |
997 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
998 | } | |
1da177e4 | 999 | seq_putc(m, ' '); |
c32c2f63 | 1000 | seq_path(m, &mnt_path, " \t\n\\"); |
1da177e4 | 1001 | seq_putc(m, ' '); |
2d4d4864 | 1002 | show_type(m, mnt->mnt_sb); |
2e4b7fcd | 1003 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
2069f457 EP |
1004 | err = show_sb_opts(m, mnt->mnt_sb); |
1005 | if (err) | |
1006 | goto out; | |
2d4d4864 | 1007 | show_mnt_opts(m, mnt); |
1da177e4 LT |
1008 | if (mnt->mnt_sb->s_op->show_options) |
1009 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
1010 | seq_puts(m, " 0 0\n"); | |
2069f457 | 1011 | out: |
1da177e4 LT |
1012 | return err; |
1013 | } | |
1014 | ||
a1a2c409 | 1015 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1016 | .start = m_start, |
1017 | .next = m_next, | |
1018 | .stop = m_stop, | |
1019 | .show = show_vfsmnt | |
1020 | }; | |
1021 | ||
2d4d4864 RP |
1022 | static int show_mountinfo(struct seq_file *m, void *v) |
1023 | { | |
1024 | struct proc_mounts *p = m->private; | |
1025 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
3376f34f | 1026 | struct mount *r = real_mount(mnt); |
2d4d4864 RP |
1027 | struct super_block *sb = mnt->mnt_sb; |
1028 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; | |
1029 | struct path root = p->root; | |
1030 | int err = 0; | |
1031 | ||
0714a533 | 1032 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, r->mnt_parent->mnt.mnt_id, |
2d4d4864 | 1033 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); |
c7f404b4 AV |
1034 | if (sb->s_op->show_path) |
1035 | err = sb->s_op->show_path(m, mnt); | |
1036 | else | |
1037 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); | |
1038 | if (err) | |
1039 | goto out; | |
2d4d4864 | 1040 | seq_putc(m, ' '); |
02125a82 AV |
1041 | |
1042 | /* mountpoints outside of chroot jail will give SEQ_SKIP on this */ | |
1043 | err = seq_path_root(m, &mnt_path, &root, " \t\n\\"); | |
1044 | if (err) | |
1045 | goto out; | |
1046 | ||
2d4d4864 RP |
1047 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); |
1048 | show_mnt_opts(m, mnt); | |
1049 | ||
1050 | /* Tagged fields ("foo:X" or "bar") */ | |
1051 | if (IS_MNT_SHARED(mnt)) | |
1052 | seq_printf(m, " shared:%i", mnt->mnt_group_id); | |
d10e8def | 1053 | if (IS_MNT_SLAVE(r)) { |
32301920 | 1054 | int master = r->mnt_master->mnt.mnt_group_id; |
6fc7871f | 1055 | int dom = get_dominating_id(r, &p->root); |
97e7e0f7 MS |
1056 | seq_printf(m, " master:%i", master); |
1057 | if (dom && dom != master) | |
1058 | seq_printf(m, " propagate_from:%i", dom); | |
1059 | } | |
2d4d4864 RP |
1060 | if (IS_MNT_UNBINDABLE(mnt)) |
1061 | seq_puts(m, " unbindable"); | |
1062 | ||
1063 | /* Filesystem specific data */ | |
1064 | seq_puts(m, " - "); | |
1065 | show_type(m, sb); | |
1066 | seq_putc(m, ' '); | |
c7f404b4 AV |
1067 | if (sb->s_op->show_devname) |
1068 | err = sb->s_op->show_devname(m, mnt); | |
1069 | else | |
1070 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
1071 | if (err) | |
1072 | goto out; | |
2d4d4864 | 1073 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); |
2069f457 EP |
1074 | err = show_sb_opts(m, sb); |
1075 | if (err) | |
1076 | goto out; | |
2d4d4864 RP |
1077 | if (sb->s_op->show_options) |
1078 | err = sb->s_op->show_options(m, mnt); | |
1079 | seq_putc(m, '\n'); | |
2069f457 | 1080 | out: |
2d4d4864 RP |
1081 | return err; |
1082 | } | |
1083 | ||
1084 | const struct seq_operations mountinfo_op = { | |
1085 | .start = m_start, | |
1086 | .next = m_next, | |
1087 | .stop = m_stop, | |
1088 | .show = show_mountinfo, | |
1089 | }; | |
1090 | ||
b4629fe2 CL |
1091 | static int show_vfsstat(struct seq_file *m, void *v) |
1092 | { | |
b0765fb8 | 1093 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
c32c2f63 | 1094 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
b4629fe2 CL |
1095 | int err = 0; |
1096 | ||
1097 | /* device */ | |
c7f404b4 | 1098 | if (mnt->mnt_sb->s_op->show_devname) { |
a877ee03 | 1099 | seq_puts(m, "device "); |
c7f404b4 AV |
1100 | err = mnt->mnt_sb->s_op->show_devname(m, mnt); |
1101 | } else { | |
1102 | if (mnt->mnt_devname) { | |
1103 | seq_puts(m, "device "); | |
1104 | mangle(m, mnt->mnt_devname); | |
1105 | } else | |
1106 | seq_puts(m, "no device"); | |
1107 | } | |
b4629fe2 CL |
1108 | |
1109 | /* mount point */ | |
1110 | seq_puts(m, " mounted on "); | |
c32c2f63 | 1111 | seq_path(m, &mnt_path, " \t\n\\"); |
b4629fe2 CL |
1112 | seq_putc(m, ' '); |
1113 | ||
1114 | /* file system type */ | |
1115 | seq_puts(m, "with fstype "); | |
2d4d4864 | 1116 | show_type(m, mnt->mnt_sb); |
b4629fe2 CL |
1117 | |
1118 | /* optional statistics */ | |
1119 | if (mnt->mnt_sb->s_op->show_stats) { | |
1120 | seq_putc(m, ' '); | |
c7f404b4 AV |
1121 | if (!err) |
1122 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); | |
b4629fe2 CL |
1123 | } |
1124 | ||
1125 | seq_putc(m, '\n'); | |
1126 | return err; | |
1127 | } | |
1128 | ||
a1a2c409 | 1129 | const struct seq_operations mountstats_op = { |
b4629fe2 CL |
1130 | .start = m_start, |
1131 | .next = m_next, | |
1132 | .stop = m_stop, | |
1133 | .show = show_vfsstat, | |
1134 | }; | |
a1a2c409 | 1135 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1136 | |
1da177e4 LT |
1137 | /** |
1138 | * may_umount_tree - check if a mount tree is busy | |
1139 | * @mnt: root of mount tree | |
1140 | * | |
1141 | * This is called to check if a tree of mounts has any | |
1142 | * open files, pwds, chroots or sub mounts that are | |
1143 | * busy. | |
1144 | */ | |
1145 | int may_umount_tree(struct vfsmount *mnt) | |
1146 | { | |
36341f64 RP |
1147 | int actual_refs = 0; |
1148 | int minimum_refs = 0; | |
315fc83e AV |
1149 | struct mount *p; |
1150 | BUG_ON(!mnt); | |
1da177e4 | 1151 | |
b3e19d92 NP |
1152 | /* write lock needed for mnt_get_count */ |
1153 | br_write_lock(vfsmount_lock); | |
315fc83e | 1154 | for (p = real_mount(mnt); p; p = next_mnt(p, mnt)) { |
83adc753 | 1155 | actual_refs += mnt_get_count(p); |
1da177e4 | 1156 | minimum_refs += 2; |
1da177e4 | 1157 | } |
b3e19d92 | 1158 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
1159 | |
1160 | if (actual_refs > minimum_refs) | |
e3474a8e | 1161 | return 0; |
1da177e4 | 1162 | |
e3474a8e | 1163 | return 1; |
1da177e4 LT |
1164 | } |
1165 | ||
1166 | EXPORT_SYMBOL(may_umount_tree); | |
1167 | ||
1168 | /** | |
1169 | * may_umount - check if a mount point is busy | |
1170 | * @mnt: root of mount | |
1171 | * | |
1172 | * This is called to check if a mount point has any | |
1173 | * open files, pwds, chroots or sub mounts. If the | |
1174 | * mount has sub mounts this will return busy | |
1175 | * regardless of whether the sub mounts are busy. | |
1176 | * | |
1177 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1178 | * give false negatives. The main reason why it's here is that we need | |
1179 | * a non-destructive way to look for easily umountable filesystems. | |
1180 | */ | |
1181 | int may_umount(struct vfsmount *mnt) | |
1182 | { | |
e3474a8e | 1183 | int ret = 1; |
8ad08d8a | 1184 | down_read(&namespace_sem); |
b3e19d92 | 1185 | br_write_lock(vfsmount_lock); |
1ab59738 | 1186 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1187 | ret = 0; |
b3e19d92 | 1188 | br_write_unlock(vfsmount_lock); |
8ad08d8a | 1189 | up_read(&namespace_sem); |
a05964f3 | 1190 | return ret; |
1da177e4 LT |
1191 | } |
1192 | ||
1193 | EXPORT_SYMBOL(may_umount); | |
1194 | ||
b90fa9ae | 1195 | void release_mounts(struct list_head *head) |
70fbcdf4 | 1196 | { |
d5e50f74 | 1197 | struct mount *mnt; |
bf066c7d | 1198 | while (!list_empty(head)) { |
1b8e5564 AV |
1199 | mnt = list_first_entry(head, struct mount, mnt_hash); |
1200 | list_del_init(&mnt->mnt_hash); | |
676da58d | 1201 | if (mnt_has_parent(mnt)) { |
70fbcdf4 RP |
1202 | struct dentry *dentry; |
1203 | struct vfsmount *m; | |
99b7db7b NP |
1204 | |
1205 | br_write_lock(vfsmount_lock); | |
a73324da | 1206 | dentry = mnt->mnt_mountpoint; |
0714a533 | 1207 | m = &mnt->mnt_parent->mnt; |
a73324da | 1208 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
0714a533 | 1209 | mnt->mnt_parent = mnt; |
7c4b93d8 | 1210 | m->mnt_ghosts--; |
99b7db7b | 1211 | br_write_unlock(vfsmount_lock); |
70fbcdf4 RP |
1212 | dput(dentry); |
1213 | mntput(m); | |
1214 | } | |
d5e50f74 | 1215 | mntput(&mnt->mnt); |
70fbcdf4 RP |
1216 | } |
1217 | } | |
1218 | ||
99b7db7b NP |
1219 | /* |
1220 | * vfsmount lock must be held for write | |
1221 | * namespace_sem must be held for write | |
1222 | */ | |
761d5c38 | 1223 | void umount_tree(struct mount *mnt, int propagate, struct list_head *kill) |
1da177e4 | 1224 | { |
7b8a53fd | 1225 | LIST_HEAD(tmp_list); |
315fc83e | 1226 | struct mount *p; |
1da177e4 | 1227 | |
761d5c38 | 1228 | for (p = mnt; p; p = next_mnt(p, &mnt->mnt)) |
1b8e5564 | 1229 | list_move(&p->mnt_hash, &tmp_list); |
1da177e4 | 1230 | |
a05964f3 | 1231 | if (propagate) |
7b8a53fd | 1232 | propagate_umount(&tmp_list); |
a05964f3 | 1233 | |
1b8e5564 | 1234 | list_for_each_entry(p, &tmp_list, mnt_hash) { |
6776db3d | 1235 | list_del_init(&p->mnt_expire); |
315fc83e AV |
1236 | list_del_init(&p->mnt.mnt_list); |
1237 | __touch_mnt_namespace(p->mnt.mnt_ns); | |
1238 | p->mnt.mnt_ns = NULL; | |
83adc753 | 1239 | __mnt_make_shortterm(p); |
6b41d536 | 1240 | list_del_init(&p->mnt_child); |
676da58d | 1241 | if (mnt_has_parent(p)) { |
0714a533 | 1242 | p->mnt_parent->mnt.mnt_ghosts++; |
a73324da | 1243 | dentry_reset_mounted(p->mnt_mountpoint); |
7c4b93d8 | 1244 | } |
0f0afb1d | 1245 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 | 1246 | } |
7b8a53fd | 1247 | list_splice(&tmp_list, kill); |
1da177e4 LT |
1248 | } |
1249 | ||
692afc31 | 1250 | static void shrink_submounts(struct mount *mnt, struct list_head *umounts); |
c35038be | 1251 | |
1ab59738 | 1252 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1253 | { |
1ab59738 | 1254 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 | 1255 | int retval; |
70fbcdf4 | 1256 | LIST_HEAD(umount_list); |
1da177e4 | 1257 | |
1ab59738 | 1258 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1259 | if (retval) |
1260 | return retval; | |
1261 | ||
1262 | /* | |
1263 | * Allow userspace to request a mountpoint be expired rather than | |
1264 | * unmounting unconditionally. Unmount only happens if: | |
1265 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1266 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1267 | */ | |
1268 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1269 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1270 | flags & (MNT_FORCE | MNT_DETACH)) |
1271 | return -EINVAL; | |
1272 | ||
b3e19d92 NP |
1273 | /* |
1274 | * probably don't strictly need the lock here if we examined | |
1275 | * all race cases, but it's a slowpath. | |
1276 | */ | |
1277 | br_write_lock(vfsmount_lock); | |
83adc753 | 1278 | if (mnt_get_count(mnt) != 2) { |
bf9faa2a | 1279 | br_write_unlock(vfsmount_lock); |
1da177e4 | 1280 | return -EBUSY; |
b3e19d92 NP |
1281 | } |
1282 | br_write_unlock(vfsmount_lock); | |
1da177e4 | 1283 | |
1ab59738 | 1284 | if (!xchg(&mnt->mnt.mnt_expiry_mark, 1)) |
1da177e4 LT |
1285 | return -EAGAIN; |
1286 | } | |
1287 | ||
1288 | /* | |
1289 | * If we may have to abort operations to get out of this | |
1290 | * mount, and they will themselves hold resources we must | |
1291 | * allow the fs to do things. In the Unix tradition of | |
1292 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1293 | * might fail to complete on the first run through as other tasks | |
1294 | * must return, and the like. Thats for the mount program to worry | |
1295 | * about for the moment. | |
1296 | */ | |
1297 | ||
42faad99 | 1298 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1299 | sb->s_op->umount_begin(sb); |
42faad99 | 1300 | } |
1da177e4 LT |
1301 | |
1302 | /* | |
1303 | * No sense to grab the lock for this test, but test itself looks | |
1304 | * somewhat bogus. Suggestions for better replacement? | |
1305 | * Ho-hum... In principle, we might treat that as umount + switch | |
1306 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1307 | * Actually it makes sense, especially if rootfs would contain a | |
1308 | * /reboot - static binary that would close all descriptors and | |
1309 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1310 | */ | |
1ab59738 | 1311 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1312 | /* |
1313 | * Special case for "unmounting" root ... | |
1314 | * we just try to remount it readonly. | |
1315 | */ | |
1316 | down_write(&sb->s_umount); | |
4aa98cf7 | 1317 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1318 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1319 | up_write(&sb->s_umount); |
1320 | return retval; | |
1321 | } | |
1322 | ||
390c6843 | 1323 | down_write(&namespace_sem); |
99b7db7b | 1324 | br_write_lock(vfsmount_lock); |
5addc5dd | 1325 | event++; |
1da177e4 | 1326 | |
c35038be | 1327 | if (!(flags & MNT_DETACH)) |
1ab59738 | 1328 | shrink_submounts(mnt, &umount_list); |
c35038be | 1329 | |
1da177e4 | 1330 | retval = -EBUSY; |
a05964f3 | 1331 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1ab59738 AV |
1332 | if (!list_empty(&mnt->mnt.mnt_list)) |
1333 | umount_tree(mnt, 1, &umount_list); | |
1da177e4 LT |
1334 | retval = 0; |
1335 | } | |
99b7db7b | 1336 | br_write_unlock(vfsmount_lock); |
390c6843 | 1337 | up_write(&namespace_sem); |
70fbcdf4 | 1338 | release_mounts(&umount_list); |
1da177e4 LT |
1339 | return retval; |
1340 | } | |
1341 | ||
1342 | /* | |
1343 | * Now umount can handle mount points as well as block devices. | |
1344 | * This is important for filesystems which use unnamed block devices. | |
1345 | * | |
1346 | * We now support a flag for forced unmount like the other 'big iron' | |
1347 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1348 | */ | |
1349 | ||
bdc480e3 | 1350 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1351 | { |
2d8f3038 | 1352 | struct path path; |
900148dc | 1353 | struct mount *mnt; |
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; | |
900148dc | 1366 | mnt = real_mount(path.mnt); |
1da177e4 | 1367 | retval = -EINVAL; |
2d8f3038 | 1368 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1369 | goto dput_and_out; |
2d8f3038 | 1370 | if (!check_mnt(path.mnt)) |
1da177e4 LT |
1371 | goto dput_and_out; |
1372 | ||
1373 | retval = -EPERM; | |
1374 | if (!capable(CAP_SYS_ADMIN)) | |
1375 | goto dput_and_out; | |
1376 | ||
900148dc | 1377 | retval = do_umount(mnt, flags); |
1da177e4 | 1378 | dput_and_out: |
429731b1 | 1379 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 | 1380 | dput(path.dentry); |
900148dc | 1381 | mntput_no_expire(mnt); |
1da177e4 LT |
1382 | out: |
1383 | return retval; | |
1384 | } | |
1385 | ||
1386 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1387 | ||
1388 | /* | |
b58fed8b | 1389 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1390 | */ |
bdc480e3 | 1391 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1392 | { |
b58fed8b | 1393 | return sys_umount(name, 0); |
1da177e4 LT |
1394 | } |
1395 | ||
1396 | #endif | |
1397 | ||
2d92ab3c | 1398 | static int mount_is_safe(struct path *path) |
1da177e4 LT |
1399 | { |
1400 | if (capable(CAP_SYS_ADMIN)) | |
1401 | return 0; | |
1402 | return -EPERM; | |
1403 | #ifdef notyet | |
2d92ab3c | 1404 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
1da177e4 | 1405 | return -EPERM; |
2d92ab3c | 1406 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
da9592ed | 1407 | if (current_uid() != path->dentry->d_inode->i_uid) |
1da177e4 LT |
1408 | return -EPERM; |
1409 | } | |
2d92ab3c | 1410 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
1da177e4 LT |
1411 | return -EPERM; |
1412 | return 0; | |
1413 | #endif | |
1414 | } | |
1415 | ||
87129cc0 | 1416 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1417 | int flag) |
1da177e4 | 1418 | { |
a73324da | 1419 | struct mount *res, *p, *q, *r; |
1a390689 | 1420 | struct path path; |
1da177e4 | 1421 | |
87129cc0 | 1422 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(&mnt->mnt)) |
9676f0c6 RP |
1423 | return NULL; |
1424 | ||
36341f64 | 1425 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
1426 | if (!q) |
1427 | goto Enomem; | |
a73324da | 1428 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1429 | |
1430 | p = mnt; | |
6b41d536 | 1431 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1432 | struct mount *s; |
7ec02ef1 | 1433 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1434 | continue; |
1435 | ||
a73324da | 1436 | for (s = r; s; s = next_mnt(s, &r->mnt)) { |
315fc83e | 1437 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(&s->mnt)) { |
9676f0c6 RP |
1438 | s = skip_mnt_tree(s); |
1439 | continue; | |
1440 | } | |
0714a533 AV |
1441 | while (p != s->mnt_parent) { |
1442 | p = p->mnt_parent; | |
1443 | q = q->mnt_parent; | |
1da177e4 | 1444 | } |
87129cc0 | 1445 | p = s; |
cb338d06 | 1446 | path.mnt = &q->mnt; |
a73324da | 1447 | path.dentry = p->mnt_mountpoint; |
87129cc0 | 1448 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
1da177e4 LT |
1449 | if (!q) |
1450 | goto Enomem; | |
99b7db7b | 1451 | br_write_lock(vfsmount_lock); |
cb338d06 AV |
1452 | list_add_tail(&q->mnt.mnt_list, &res->mnt.mnt_list); |
1453 | attach_mnt(q, &path); | |
99b7db7b | 1454 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
1455 | } |
1456 | } | |
1457 | return res; | |
b58fed8b | 1458 | Enomem: |
1da177e4 | 1459 | if (res) { |
70fbcdf4 | 1460 | LIST_HEAD(umount_list); |
99b7db7b | 1461 | br_write_lock(vfsmount_lock); |
761d5c38 | 1462 | umount_tree(res, 0, &umount_list); |
99b7db7b | 1463 | br_write_unlock(vfsmount_lock); |
70fbcdf4 | 1464 | release_mounts(&umount_list); |
1da177e4 LT |
1465 | } |
1466 | return NULL; | |
1467 | } | |
1468 | ||
589ff870 | 1469 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 | 1470 | { |
cb338d06 | 1471 | struct mount *tree; |
1a60a280 | 1472 | down_write(&namespace_sem); |
87129cc0 AV |
1473 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
1474 | CL_COPY_ALL | CL_PRIVATE); | |
1a60a280 | 1475 | up_write(&namespace_sem); |
cb338d06 | 1476 | return tree ? &tree->mnt : NULL; |
8aec0809 AV |
1477 | } |
1478 | ||
1479 | void drop_collected_mounts(struct vfsmount *mnt) | |
1480 | { | |
1481 | LIST_HEAD(umount_list); | |
1a60a280 | 1482 | down_write(&namespace_sem); |
99b7db7b | 1483 | br_write_lock(vfsmount_lock); |
761d5c38 | 1484 | umount_tree(real_mount(mnt), 0, &umount_list); |
99b7db7b | 1485 | br_write_unlock(vfsmount_lock); |
1a60a280 | 1486 | up_write(&namespace_sem); |
8aec0809 AV |
1487 | release_mounts(&umount_list); |
1488 | } | |
1489 | ||
1f707137 AV |
1490 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1491 | struct vfsmount *root) | |
1492 | { | |
1493 | struct vfsmount *mnt; | |
1494 | int res = f(root, arg); | |
1495 | if (res) | |
1496 | return res; | |
1497 | list_for_each_entry(mnt, &root->mnt_list, mnt_list) { | |
1498 | res = f(mnt, arg); | |
1499 | if (res) | |
1500 | return res; | |
1501 | } | |
1502 | return 0; | |
1503 | } | |
1504 | ||
4b8b21f4 | 1505 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 1506 | { |
315fc83e | 1507 | struct mount *p; |
719f5d7f | 1508 | |
4b8b21f4 | 1509 | for (p = mnt; p != end; p = next_mnt(p, &mnt->mnt)) { |
315fc83e | 1510 | if (p->mnt.mnt_group_id && !IS_MNT_SHARED(&p->mnt)) |
4b8b21f4 | 1511 | mnt_release_group_id(p); |
719f5d7f MS |
1512 | } |
1513 | } | |
1514 | ||
4b8b21f4 | 1515 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 1516 | { |
315fc83e | 1517 | struct mount *p; |
719f5d7f | 1518 | |
4b8b21f4 | 1519 | for (p = mnt; p; p = recurse ? next_mnt(p, &mnt->mnt) : NULL) { |
315fc83e | 1520 | if (!p->mnt.mnt_group_id && !IS_MNT_SHARED(&p->mnt)) { |
4b8b21f4 | 1521 | int err = mnt_alloc_group_id(p); |
719f5d7f | 1522 | if (err) { |
4b8b21f4 | 1523 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
1524 | return err; |
1525 | } | |
1526 | } | |
1527 | } | |
1528 | ||
1529 | return 0; | |
1530 | } | |
1531 | ||
b90fa9ae RP |
1532 | /* |
1533 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1534 | * @nd : place the mount tree @source_mnt is attached |
1535 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1536 | * store the parent mount and mountpoint dentry. | |
1537 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1538 | * |
1539 | * NOTE: in the table below explains the semantics when a source mount | |
1540 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1541 | * --------------------------------------------------------------------------- |
1542 | * | BIND MOUNT OPERATION | | |
1543 | * |************************************************************************** | |
1544 | * | source-->| shared | private | slave | unbindable | | |
1545 | * | dest | | | | | | |
1546 | * | | | | | | | | |
1547 | * | v | | | | | | |
1548 | * |************************************************************************** | |
1549 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1550 | * | | | | | | | |
1551 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1552 | * *************************************************************************** | |
b90fa9ae RP |
1553 | * A bind operation clones the source mount and mounts the clone on the |
1554 | * destination mount. | |
1555 | * | |
1556 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1557 | * tree of the destination mount and the cloned mount is added to | |
1558 | * the peer group of the source mount. | |
1559 | * (+) the cloned mount is created under the destination mount and is marked | |
1560 | * as shared. The cloned mount is added to the peer group of the source | |
1561 | * mount. | |
5afe0022 RP |
1562 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1563 | * of the destination mount and the cloned mount is made slave | |
1564 | * of the same master as that of the source mount. The cloned mount | |
1565 | * is marked as 'shared and slave'. | |
1566 | * (*) the cloned mount is made a slave of the same master as that of the | |
1567 | * source mount. | |
1568 | * | |
9676f0c6 RP |
1569 | * --------------------------------------------------------------------------- |
1570 | * | MOVE MOUNT OPERATION | | |
1571 | * |************************************************************************** | |
1572 | * | source-->| shared | private | slave | unbindable | | |
1573 | * | dest | | | | | | |
1574 | * | | | | | | | | |
1575 | * | v | | | | | | |
1576 | * |************************************************************************** | |
1577 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1578 | * | | | | | | | |
1579 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1580 | * *************************************************************************** | |
5afe0022 RP |
1581 | * |
1582 | * (+) the mount is moved to the destination. And is then propagated to | |
1583 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1584 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1585 | * (+++) the mount is moved to the destination and is then propagated to |
1586 | * all the mounts belonging to the destination mount's propagation tree. | |
1587 | * the mount is marked as 'shared and slave'. | |
1588 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1589 | * |
1590 | * if the source mount is a tree, the operations explained above is | |
1591 | * applied to each mount in the tree. | |
1592 | * Must be called without spinlocks held, since this function can sleep | |
1593 | * in allocations. | |
1594 | */ | |
0fb54e50 | 1595 | static int attach_recursive_mnt(struct mount *source_mnt, |
1a390689 | 1596 | struct path *path, struct path *parent_path) |
b90fa9ae RP |
1597 | { |
1598 | LIST_HEAD(tree_list); | |
a8d56d8e | 1599 | struct mount *dest_mnt = real_mount(path->mnt); |
1a390689 | 1600 | struct dentry *dest_dentry = path->dentry; |
315fc83e | 1601 | struct mount *child, *p; |
719f5d7f | 1602 | int err; |
b90fa9ae | 1603 | |
a8d56d8e | 1604 | if (IS_MNT_SHARED(&dest_mnt->mnt)) { |
0fb54e50 | 1605 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
1606 | if (err) |
1607 | goto out; | |
1608 | } | |
a8d56d8e | 1609 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); |
719f5d7f MS |
1610 | if (err) |
1611 | goto out_cleanup_ids; | |
b90fa9ae | 1612 | |
99b7db7b | 1613 | br_write_lock(vfsmount_lock); |
df1a1ad2 | 1614 | |
a8d56d8e | 1615 | if (IS_MNT_SHARED(&dest_mnt->mnt)) { |
0fb54e50 | 1616 | for (p = source_mnt; p; p = next_mnt(p, &source_mnt->mnt)) |
0f0afb1d | 1617 | set_mnt_shared(p); |
b90fa9ae | 1618 | } |
1a390689 | 1619 | if (parent_path) { |
0fb54e50 AV |
1620 | detach_mnt(source_mnt, parent_path); |
1621 | attach_mnt(source_mnt, path); | |
e5d67f07 | 1622 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
21444403 | 1623 | } else { |
14cf1fa8 | 1624 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); |
0fb54e50 | 1625 | commit_tree(source_mnt); |
21444403 | 1626 | } |
b90fa9ae | 1627 | |
1b8e5564 AV |
1628 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { |
1629 | list_del_init(&child->mnt_hash); | |
4b2619a5 | 1630 | commit_tree(child); |
b90fa9ae | 1631 | } |
99b7db7b NP |
1632 | br_write_unlock(vfsmount_lock); |
1633 | ||
b90fa9ae | 1634 | return 0; |
719f5d7f MS |
1635 | |
1636 | out_cleanup_ids: | |
a8d56d8e | 1637 | if (IS_MNT_SHARED(&dest_mnt->mnt)) |
0fb54e50 | 1638 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f MS |
1639 | out: |
1640 | return err; | |
b90fa9ae RP |
1641 | } |
1642 | ||
b12cea91 AV |
1643 | static int lock_mount(struct path *path) |
1644 | { | |
1645 | struct vfsmount *mnt; | |
1646 | retry: | |
1647 | mutex_lock(&path->dentry->d_inode->i_mutex); | |
1648 | if (unlikely(cant_mount(path->dentry))) { | |
1649 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
1650 | return -ENOENT; | |
1651 | } | |
1652 | down_write(&namespace_sem); | |
1653 | mnt = lookup_mnt(path); | |
1654 | if (likely(!mnt)) | |
1655 | return 0; | |
1656 | up_write(&namespace_sem); | |
1657 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
1658 | path_put(path); | |
1659 | path->mnt = mnt; | |
1660 | path->dentry = dget(mnt->mnt_root); | |
1661 | goto retry; | |
1662 | } | |
1663 | ||
1664 | static void unlock_mount(struct path *path) | |
1665 | { | |
1666 | up_write(&namespace_sem); | |
1667 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
1668 | } | |
1669 | ||
95bc5f25 | 1670 | static int graft_tree(struct mount *mnt, struct path *path) |
1da177e4 | 1671 | { |
95bc5f25 | 1672 | if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER) |
1da177e4 LT |
1673 | return -EINVAL; |
1674 | ||
8c3ee42e | 1675 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
95bc5f25 | 1676 | S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode)) |
1da177e4 LT |
1677 | return -ENOTDIR; |
1678 | ||
b12cea91 AV |
1679 | if (d_unlinked(path->dentry)) |
1680 | return -ENOENT; | |
1da177e4 | 1681 | |
95bc5f25 | 1682 | return attach_recursive_mnt(mnt, path, NULL); |
1da177e4 LT |
1683 | } |
1684 | ||
7a2e8a8f VA |
1685 | /* |
1686 | * Sanity check the flags to change_mnt_propagation. | |
1687 | */ | |
1688 | ||
1689 | static int flags_to_propagation_type(int flags) | |
1690 | { | |
7c6e984d | 1691 | int type = flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
1692 | |
1693 | /* Fail if any non-propagation flags are set */ | |
1694 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
1695 | return 0; | |
1696 | /* Only one propagation flag should be set */ | |
1697 | if (!is_power_of_2(type)) | |
1698 | return 0; | |
1699 | return type; | |
1700 | } | |
1701 | ||
07b20889 RP |
1702 | /* |
1703 | * recursively change the type of the mountpoint. | |
1704 | */ | |
0a0d8a46 | 1705 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1706 | { |
315fc83e | 1707 | struct mount *m; |
4b8b21f4 | 1708 | struct mount *mnt = real_mount(path->mnt); |
07b20889 | 1709 | int recurse = flag & MS_REC; |
7a2e8a8f | 1710 | int type; |
719f5d7f | 1711 | int err = 0; |
07b20889 | 1712 | |
ee6f9582 MS |
1713 | if (!capable(CAP_SYS_ADMIN)) |
1714 | return -EPERM; | |
1715 | ||
2d92ab3c | 1716 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
1717 | return -EINVAL; |
1718 | ||
7a2e8a8f VA |
1719 | type = flags_to_propagation_type(flag); |
1720 | if (!type) | |
1721 | return -EINVAL; | |
1722 | ||
07b20889 | 1723 | down_write(&namespace_sem); |
719f5d7f MS |
1724 | if (type == MS_SHARED) { |
1725 | err = invent_group_ids(mnt, recurse); | |
1726 | if (err) | |
1727 | goto out_unlock; | |
1728 | } | |
1729 | ||
99b7db7b | 1730 | br_write_lock(vfsmount_lock); |
4b8b21f4 | 1731 | for (m = mnt; m; m = (recurse ? next_mnt(m, &mnt->mnt) : NULL)) |
0f0afb1d | 1732 | change_mnt_propagation(m, type); |
99b7db7b | 1733 | br_write_unlock(vfsmount_lock); |
719f5d7f MS |
1734 | |
1735 | out_unlock: | |
07b20889 | 1736 | up_write(&namespace_sem); |
719f5d7f | 1737 | return err; |
07b20889 RP |
1738 | } |
1739 | ||
1da177e4 LT |
1740 | /* |
1741 | * do loopback mount. | |
1742 | */ | |
0a0d8a46 | 1743 | static int do_loopback(struct path *path, char *old_name, |
2dafe1c4 | 1744 | int recurse) |
1da177e4 | 1745 | { |
b12cea91 | 1746 | LIST_HEAD(umount_list); |
2d92ab3c | 1747 | struct path old_path; |
87129cc0 | 1748 | struct mount *mnt = NULL, *old; |
2d92ab3c | 1749 | int err = mount_is_safe(path); |
1da177e4 LT |
1750 | if (err) |
1751 | return err; | |
1752 | if (!old_name || !*old_name) | |
1753 | return -EINVAL; | |
815d405c | 1754 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
1755 | if (err) |
1756 | return err; | |
1757 | ||
b12cea91 AV |
1758 | err = lock_mount(path); |
1759 | if (err) | |
1760 | goto out; | |
1761 | ||
87129cc0 AV |
1762 | old = real_mount(old_path.mnt); |
1763 | ||
1da177e4 | 1764 | err = -EINVAL; |
2d92ab3c | 1765 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
b12cea91 | 1766 | goto out2; |
9676f0c6 | 1767 | |
2d92ab3c | 1768 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
b12cea91 | 1769 | goto out2; |
1da177e4 | 1770 | |
ccd48bc7 AV |
1771 | err = -ENOMEM; |
1772 | if (recurse) | |
87129cc0 | 1773 | mnt = copy_tree(old, old_path.dentry, 0); |
ccd48bc7 | 1774 | else |
87129cc0 | 1775 | mnt = clone_mnt(old, old_path.dentry, 0); |
ccd48bc7 AV |
1776 | |
1777 | if (!mnt) | |
b12cea91 | 1778 | goto out2; |
ccd48bc7 | 1779 | |
95bc5f25 | 1780 | err = graft_tree(mnt, path); |
ccd48bc7 | 1781 | if (err) { |
99b7db7b | 1782 | br_write_lock(vfsmount_lock); |
761d5c38 | 1783 | umount_tree(mnt, 0, &umount_list); |
99b7db7b | 1784 | br_write_unlock(vfsmount_lock); |
5b83d2c5 | 1785 | } |
b12cea91 AV |
1786 | out2: |
1787 | unlock_mount(path); | |
1788 | release_mounts(&umount_list); | |
ccd48bc7 | 1789 | out: |
2d92ab3c | 1790 | path_put(&old_path); |
1da177e4 LT |
1791 | return err; |
1792 | } | |
1793 | ||
2e4b7fcd DH |
1794 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
1795 | { | |
1796 | int error = 0; | |
1797 | int readonly_request = 0; | |
1798 | ||
1799 | if (ms_flags & MS_RDONLY) | |
1800 | readonly_request = 1; | |
1801 | if (readonly_request == __mnt_is_readonly(mnt)) | |
1802 | return 0; | |
1803 | ||
1804 | if (readonly_request) | |
83adc753 | 1805 | error = mnt_make_readonly(real_mount(mnt)); |
2e4b7fcd | 1806 | else |
83adc753 | 1807 | __mnt_unmake_readonly(real_mount(mnt)); |
2e4b7fcd DH |
1808 | return error; |
1809 | } | |
1810 | ||
1da177e4 LT |
1811 | /* |
1812 | * change filesystem flags. dir should be a physical root of filesystem. | |
1813 | * If you've mounted a non-root directory somewhere and want to do remount | |
1814 | * on it - tough luck. | |
1815 | */ | |
0a0d8a46 | 1816 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
1817 | void *data) |
1818 | { | |
1819 | int err; | |
2d92ab3c | 1820 | struct super_block *sb = path->mnt->mnt_sb; |
1da177e4 LT |
1821 | |
1822 | if (!capable(CAP_SYS_ADMIN)) | |
1823 | return -EPERM; | |
1824 | ||
2d92ab3c | 1825 | if (!check_mnt(path->mnt)) |
1da177e4 LT |
1826 | return -EINVAL; |
1827 | ||
2d92ab3c | 1828 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
1829 | return -EINVAL; |
1830 | ||
ff36fe2c EP |
1831 | err = security_sb_remount(sb, data); |
1832 | if (err) | |
1833 | return err; | |
1834 | ||
1da177e4 | 1835 | down_write(&sb->s_umount); |
2e4b7fcd | 1836 | if (flags & MS_BIND) |
2d92ab3c | 1837 | err = change_mount_flags(path->mnt, flags); |
4aa98cf7 | 1838 | else |
2e4b7fcd | 1839 | err = do_remount_sb(sb, flags, data, 0); |
7b43a79f | 1840 | if (!err) { |
99b7db7b | 1841 | br_write_lock(vfsmount_lock); |
495d6c9c | 1842 | mnt_flags |= path->mnt->mnt_flags & MNT_PROPAGATION_MASK; |
2d92ab3c | 1843 | path->mnt->mnt_flags = mnt_flags; |
99b7db7b | 1844 | br_write_unlock(vfsmount_lock); |
7b43a79f | 1845 | } |
1da177e4 | 1846 | up_write(&sb->s_umount); |
0e55a7cc | 1847 | if (!err) { |
99b7db7b | 1848 | br_write_lock(vfsmount_lock); |
0e55a7cc | 1849 | touch_mnt_namespace(path->mnt->mnt_ns); |
99b7db7b | 1850 | br_write_unlock(vfsmount_lock); |
0e55a7cc | 1851 | } |
1da177e4 LT |
1852 | return err; |
1853 | } | |
1854 | ||
cbbe362c | 1855 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 1856 | { |
315fc83e | 1857 | struct mount *p; |
cbbe362c | 1858 | for (p = mnt; p; p = next_mnt(p, &mnt->mnt)) { |
315fc83e | 1859 | if (IS_MNT_UNBINDABLE(&p->mnt)) |
9676f0c6 RP |
1860 | return 1; |
1861 | } | |
1862 | return 0; | |
1863 | } | |
1864 | ||
0a0d8a46 | 1865 | static int do_move_mount(struct path *path, char *old_name) |
1da177e4 | 1866 | { |
2d92ab3c | 1867 | struct path old_path, parent_path; |
676da58d | 1868 | struct mount *p; |
0fb54e50 | 1869 | struct mount *old; |
1da177e4 LT |
1870 | int err = 0; |
1871 | if (!capable(CAP_SYS_ADMIN)) | |
1872 | return -EPERM; | |
1873 | if (!old_name || !*old_name) | |
1874 | return -EINVAL; | |
2d92ab3c | 1875 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1876 | if (err) |
1877 | return err; | |
1878 | ||
b12cea91 | 1879 | err = lock_mount(path); |
cc53ce53 DH |
1880 | if (err < 0) |
1881 | goto out; | |
1882 | ||
1da177e4 | 1883 | err = -EINVAL; |
2d92ab3c | 1884 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
1da177e4 LT |
1885 | goto out1; |
1886 | ||
f3da392e | 1887 | if (d_unlinked(path->dentry)) |
21444403 | 1888 | goto out1; |
1da177e4 LT |
1889 | |
1890 | err = -EINVAL; | |
2d92ab3c | 1891 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 1892 | goto out1; |
1da177e4 | 1893 | |
0fb54e50 AV |
1894 | old = real_mount(old_path.mnt); |
1895 | ||
676da58d | 1896 | if (!mnt_has_parent(old)) |
21444403 | 1897 | goto out1; |
1da177e4 | 1898 | |
2d92ab3c AV |
1899 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1900 | S_ISDIR(old_path.dentry->d_inode->i_mode)) | |
21444403 RP |
1901 | goto out1; |
1902 | /* | |
1903 | * Don't move a mount residing in a shared parent. | |
1904 | */ | |
0714a533 | 1905 | if (IS_MNT_SHARED(&old->mnt_parent->mnt)) |
21444403 | 1906 | goto out1; |
9676f0c6 RP |
1907 | /* |
1908 | * Don't move a mount tree containing unbindable mounts to a destination | |
1909 | * mount which is shared. | |
1910 | */ | |
2d92ab3c | 1911 | if (IS_MNT_SHARED(path->mnt) && |
cbbe362c | 1912 | tree_contains_unbindable(old)) |
9676f0c6 | 1913 | goto out1; |
1da177e4 | 1914 | err = -ELOOP; |
0714a533 | 1915 | for (p = real_mount(path->mnt); mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 1916 | if (p == old) |
21444403 | 1917 | goto out1; |
1da177e4 | 1918 | |
0fb54e50 | 1919 | err = attach_recursive_mnt(old, path, &parent_path); |
4ac91378 | 1920 | if (err) |
21444403 | 1921 | goto out1; |
1da177e4 LT |
1922 | |
1923 | /* if the mount is moved, it should no longer be expire | |
1924 | * automatically */ | |
6776db3d | 1925 | list_del_init(&old->mnt_expire); |
1da177e4 | 1926 | out1: |
b12cea91 | 1927 | unlock_mount(path); |
1da177e4 | 1928 | out: |
1da177e4 | 1929 | if (!err) |
1a390689 | 1930 | path_put(&parent_path); |
2d92ab3c | 1931 | path_put(&old_path); |
1da177e4 LT |
1932 | return err; |
1933 | } | |
1934 | ||
9d412a43 AV |
1935 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
1936 | { | |
1937 | int err; | |
1938 | const char *subtype = strchr(fstype, '.'); | |
1939 | if (subtype) { | |
1940 | subtype++; | |
1941 | err = -EINVAL; | |
1942 | if (!subtype[0]) | |
1943 | goto err; | |
1944 | } else | |
1945 | subtype = ""; | |
1946 | ||
1947 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); | |
1948 | err = -ENOMEM; | |
1949 | if (!mnt->mnt_sb->s_subtype) | |
1950 | goto err; | |
1951 | return mnt; | |
1952 | ||
1953 | err: | |
1954 | mntput(mnt); | |
1955 | return ERR_PTR(err); | |
1956 | } | |
1957 | ||
79e801a9 | 1958 | static struct vfsmount * |
9d412a43 AV |
1959 | do_kern_mount(const char *fstype, int flags, const char *name, void *data) |
1960 | { | |
1961 | struct file_system_type *type = get_fs_type(fstype); | |
1962 | struct vfsmount *mnt; | |
1963 | if (!type) | |
1964 | return ERR_PTR(-ENODEV); | |
1965 | mnt = vfs_kern_mount(type, flags, name, data); | |
1966 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && | |
1967 | !mnt->mnt_sb->s_subtype) | |
1968 | mnt = fs_set_subtype(mnt, fstype); | |
1969 | put_filesystem(type); | |
1970 | return mnt; | |
1971 | } | |
9d412a43 AV |
1972 | |
1973 | /* | |
1974 | * add a mount into a namespace's mount tree | |
1975 | */ | |
95bc5f25 | 1976 | static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) |
9d412a43 AV |
1977 | { |
1978 | int err; | |
1979 | ||
1980 | mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); | |
1981 | ||
b12cea91 AV |
1982 | err = lock_mount(path); |
1983 | if (err) | |
1984 | return err; | |
9d412a43 AV |
1985 | |
1986 | err = -EINVAL; | |
1987 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) | |
1988 | goto unlock; | |
1989 | ||
1990 | /* Refuse the same filesystem on the same mount point */ | |
1991 | err = -EBUSY; | |
95bc5f25 | 1992 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 AV |
1993 | path->mnt->mnt_root == path->dentry) |
1994 | goto unlock; | |
1995 | ||
1996 | err = -EINVAL; | |
95bc5f25 | 1997 | if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode)) |
9d412a43 AV |
1998 | goto unlock; |
1999 | ||
95bc5f25 | 2000 | newmnt->mnt.mnt_flags = mnt_flags; |
9d412a43 AV |
2001 | err = graft_tree(newmnt, path); |
2002 | ||
2003 | unlock: | |
b12cea91 | 2004 | unlock_mount(path); |
9d412a43 AV |
2005 | return err; |
2006 | } | |
b1e75df4 | 2007 | |
1da177e4 LT |
2008 | /* |
2009 | * create a new mount for userspace and request it to be added into the | |
2010 | * namespace's tree | |
2011 | */ | |
0a0d8a46 | 2012 | static int do_new_mount(struct path *path, char *type, int flags, |
1da177e4 LT |
2013 | int mnt_flags, char *name, void *data) |
2014 | { | |
2015 | struct vfsmount *mnt; | |
15f9a3f3 | 2016 | int err; |
1da177e4 | 2017 | |
eca6f534 | 2018 | if (!type) |
1da177e4 LT |
2019 | return -EINVAL; |
2020 | ||
2021 | /* we need capabilities... */ | |
2022 | if (!capable(CAP_SYS_ADMIN)) | |
2023 | return -EPERM; | |
2024 | ||
2025 | mnt = do_kern_mount(type, flags, name, data); | |
2026 | if (IS_ERR(mnt)) | |
2027 | return PTR_ERR(mnt); | |
2028 | ||
95bc5f25 | 2029 | err = do_add_mount(real_mount(mnt), path, mnt_flags); |
15f9a3f3 AV |
2030 | if (err) |
2031 | mntput(mnt); | |
2032 | return err; | |
1da177e4 LT |
2033 | } |
2034 | ||
19a167af AV |
2035 | int finish_automount(struct vfsmount *m, struct path *path) |
2036 | { | |
6776db3d | 2037 | struct mount *mnt = real_mount(m); |
19a167af AV |
2038 | int err; |
2039 | /* The new mount record should have at least 2 refs to prevent it being | |
2040 | * expired before we get a chance to add it | |
2041 | */ | |
6776db3d | 2042 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
2043 | |
2044 | if (m->mnt_sb == path->mnt->mnt_sb && | |
2045 | m->mnt_root == path->dentry) { | |
b1e75df4 AV |
2046 | err = -ELOOP; |
2047 | goto fail; | |
19a167af AV |
2048 | } |
2049 | ||
95bc5f25 | 2050 | err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
b1e75df4 AV |
2051 | if (!err) |
2052 | return 0; | |
2053 | fail: | |
2054 | /* remove m from any expiration list it may be on */ | |
6776db3d | 2055 | if (!list_empty(&mnt->mnt_expire)) { |
b1e75df4 AV |
2056 | down_write(&namespace_sem); |
2057 | br_write_lock(vfsmount_lock); | |
6776db3d | 2058 | list_del_init(&mnt->mnt_expire); |
b1e75df4 AV |
2059 | br_write_unlock(vfsmount_lock); |
2060 | up_write(&namespace_sem); | |
19a167af | 2061 | } |
b1e75df4 AV |
2062 | mntput(m); |
2063 | mntput(m); | |
19a167af AV |
2064 | return err; |
2065 | } | |
2066 | ||
ea5b778a DH |
2067 | /** |
2068 | * mnt_set_expiry - Put a mount on an expiration list | |
2069 | * @mnt: The mount to list. | |
2070 | * @expiry_list: The list to add the mount to. | |
2071 | */ | |
2072 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
2073 | { | |
2074 | down_write(&namespace_sem); | |
2075 | br_write_lock(vfsmount_lock); | |
2076 | ||
6776db3d | 2077 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a DH |
2078 | |
2079 | br_write_unlock(vfsmount_lock); | |
2080 | up_write(&namespace_sem); | |
2081 | } | |
2082 | EXPORT_SYMBOL(mnt_set_expiry); | |
2083 | ||
1da177e4 LT |
2084 | /* |
2085 | * process a list of expirable mountpoints with the intent of discarding any | |
2086 | * mountpoints that aren't in use and haven't been touched since last we came | |
2087 | * here | |
2088 | */ | |
2089 | void mark_mounts_for_expiry(struct list_head *mounts) | |
2090 | { | |
761d5c38 | 2091 | struct mount *mnt, *next; |
1da177e4 | 2092 | LIST_HEAD(graveyard); |
bcc5c7d2 | 2093 | LIST_HEAD(umounts); |
1da177e4 LT |
2094 | |
2095 | if (list_empty(mounts)) | |
2096 | return; | |
2097 | ||
bcc5c7d2 | 2098 | down_write(&namespace_sem); |
99b7db7b | 2099 | br_write_lock(vfsmount_lock); |
1da177e4 LT |
2100 | |
2101 | /* extract from the expiration list every vfsmount that matches the | |
2102 | * following criteria: | |
2103 | * - only referenced by its parent vfsmount | |
2104 | * - still marked for expiry (marked on the last call here; marks are | |
2105 | * cleared by mntput()) | |
2106 | */ | |
6776db3d | 2107 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
761d5c38 | 2108 | if (!xchg(&mnt->mnt.mnt_expiry_mark, 1) || |
1ab59738 | 2109 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 2110 | continue; |
6776db3d | 2111 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 2112 | } |
bcc5c7d2 | 2113 | while (!list_empty(&graveyard)) { |
6776db3d | 2114 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
761d5c38 | 2115 | touch_mnt_namespace(mnt->mnt.mnt_ns); |
bcc5c7d2 AV |
2116 | umount_tree(mnt, 1, &umounts); |
2117 | } | |
99b7db7b | 2118 | br_write_unlock(vfsmount_lock); |
bcc5c7d2 AV |
2119 | up_write(&namespace_sem); |
2120 | ||
2121 | release_mounts(&umounts); | |
5528f911 TM |
2122 | } |
2123 | ||
2124 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
2125 | ||
2126 | /* | |
2127 | * Ripoff of 'select_parent()' | |
2128 | * | |
2129 | * search the list of submounts for a given mountpoint, and move any | |
2130 | * shrinkable submounts to the 'graveyard' list. | |
2131 | */ | |
692afc31 | 2132 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 2133 | { |
692afc31 | 2134 | struct mount *this_parent = parent; |
5528f911 TM |
2135 | struct list_head *next; |
2136 | int found = 0; | |
2137 | ||
2138 | repeat: | |
6b41d536 | 2139 | next = this_parent->mnt_mounts.next; |
5528f911 | 2140 | resume: |
6b41d536 | 2141 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 2142 | struct list_head *tmp = next; |
6b41d536 | 2143 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
2144 | |
2145 | next = tmp->next; | |
692afc31 | 2146 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 2147 | continue; |
5528f911 TM |
2148 | /* |
2149 | * Descend a level if the d_mounts list is non-empty. | |
2150 | */ | |
6b41d536 | 2151 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
2152 | this_parent = mnt; |
2153 | goto repeat; | |
2154 | } | |
1da177e4 | 2155 | |
1ab59738 | 2156 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 2157 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
2158 | found++; |
2159 | } | |
1da177e4 | 2160 | } |
5528f911 TM |
2161 | /* |
2162 | * All done at this level ... ascend and resume the search | |
2163 | */ | |
2164 | if (this_parent != parent) { | |
6b41d536 | 2165 | next = this_parent->mnt_child.next; |
0714a533 | 2166 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
2167 | goto resume; |
2168 | } | |
2169 | return found; | |
2170 | } | |
2171 | ||
2172 | /* | |
2173 | * process a list of expirable mountpoints with the intent of discarding any | |
2174 | * submounts of a specific parent mountpoint | |
99b7db7b NP |
2175 | * |
2176 | * vfsmount_lock must be held for write | |
5528f911 | 2177 | */ |
692afc31 | 2178 | static void shrink_submounts(struct mount *mnt, struct list_head *umounts) |
5528f911 TM |
2179 | { |
2180 | LIST_HEAD(graveyard); | |
761d5c38 | 2181 | struct mount *m; |
5528f911 | 2182 | |
5528f911 | 2183 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 2184 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 2185 | while (!list_empty(&graveyard)) { |
761d5c38 | 2186 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 2187 | mnt_expire); |
761d5c38 | 2188 | touch_mnt_namespace(m->mnt.mnt_ns); |
afef80b3 | 2189 | umount_tree(m, 1, umounts); |
bcc5c7d2 AV |
2190 | } |
2191 | } | |
1da177e4 LT |
2192 | } |
2193 | ||
1da177e4 LT |
2194 | /* |
2195 | * Some copy_from_user() implementations do not return the exact number of | |
2196 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
2197 | * Note that this function differs from copy_from_user() in that it will oops | |
2198 | * on bad values of `to', rather than returning a short copy. | |
2199 | */ | |
b58fed8b RP |
2200 | static long exact_copy_from_user(void *to, const void __user * from, |
2201 | unsigned long n) | |
1da177e4 LT |
2202 | { |
2203 | char *t = to; | |
2204 | const char __user *f = from; | |
2205 | char c; | |
2206 | ||
2207 | if (!access_ok(VERIFY_READ, from, n)) | |
2208 | return n; | |
2209 | ||
2210 | while (n) { | |
2211 | if (__get_user(c, f)) { | |
2212 | memset(t, 0, n); | |
2213 | break; | |
2214 | } | |
2215 | *t++ = c; | |
2216 | f++; | |
2217 | n--; | |
2218 | } | |
2219 | return n; | |
2220 | } | |
2221 | ||
b58fed8b | 2222 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
2223 | { |
2224 | int i; | |
2225 | unsigned long page; | |
2226 | unsigned long size; | |
b58fed8b | 2227 | |
1da177e4 LT |
2228 | *where = 0; |
2229 | if (!data) | |
2230 | return 0; | |
2231 | ||
2232 | if (!(page = __get_free_page(GFP_KERNEL))) | |
2233 | return -ENOMEM; | |
2234 | ||
2235 | /* We only care that *some* data at the address the user | |
2236 | * gave us is valid. Just in case, we'll zero | |
2237 | * the remainder of the page. | |
2238 | */ | |
2239 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
2240 | size = TASK_SIZE - (unsigned long)data; | |
2241 | if (size > PAGE_SIZE) | |
2242 | size = PAGE_SIZE; | |
2243 | ||
2244 | i = size - exact_copy_from_user((void *)page, data, size); | |
2245 | if (!i) { | |
b58fed8b | 2246 | free_page(page); |
1da177e4 LT |
2247 | return -EFAULT; |
2248 | } | |
2249 | if (i != PAGE_SIZE) | |
2250 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
2251 | *where = page; | |
2252 | return 0; | |
2253 | } | |
2254 | ||
eca6f534 VN |
2255 | int copy_mount_string(const void __user *data, char **where) |
2256 | { | |
2257 | char *tmp; | |
2258 | ||
2259 | if (!data) { | |
2260 | *where = NULL; | |
2261 | return 0; | |
2262 | } | |
2263 | ||
2264 | tmp = strndup_user(data, PAGE_SIZE); | |
2265 | if (IS_ERR(tmp)) | |
2266 | return PTR_ERR(tmp); | |
2267 | ||
2268 | *where = tmp; | |
2269 | return 0; | |
2270 | } | |
2271 | ||
1da177e4 LT |
2272 | /* |
2273 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
2274 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
2275 | * | |
2276 | * data is a (void *) that can point to any structure up to | |
2277 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
2278 | * information (or be NULL). | |
2279 | * | |
2280 | * Pre-0.97 versions of mount() didn't have a flags word. | |
2281 | * When the flags word was introduced its top half was required | |
2282 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
2283 | * Therefore, if this magic number is present, it carries no information | |
2284 | * and must be discarded. | |
2285 | */ | |
b58fed8b | 2286 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
2287 | unsigned long flags, void *data_page) |
2288 | { | |
2d92ab3c | 2289 | struct path path; |
1da177e4 LT |
2290 | int retval = 0; |
2291 | int mnt_flags = 0; | |
2292 | ||
2293 | /* Discard magic */ | |
2294 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
2295 | flags &= ~MS_MGC_MSK; | |
2296 | ||
2297 | /* Basic sanity checks */ | |
2298 | ||
2299 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
2300 | return -EINVAL; | |
1da177e4 LT |
2301 | |
2302 | if (data_page) | |
2303 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
2304 | ||
a27ab9f2 TH |
2305 | /* ... and get the mountpoint */ |
2306 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); | |
2307 | if (retval) | |
2308 | return retval; | |
2309 | ||
2310 | retval = security_sb_mount(dev_name, &path, | |
2311 | type_page, flags, data_page); | |
2312 | if (retval) | |
2313 | goto dput_out; | |
2314 | ||
613cbe3d AK |
2315 | /* Default to relatime unless overriden */ |
2316 | if (!(flags & MS_NOATIME)) | |
2317 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 2318 | |
1da177e4 LT |
2319 | /* Separate the per-mountpoint flags */ |
2320 | if (flags & MS_NOSUID) | |
2321 | mnt_flags |= MNT_NOSUID; | |
2322 | if (flags & MS_NODEV) | |
2323 | mnt_flags |= MNT_NODEV; | |
2324 | if (flags & MS_NOEXEC) | |
2325 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
2326 | if (flags & MS_NOATIME) |
2327 | mnt_flags |= MNT_NOATIME; | |
2328 | if (flags & MS_NODIRATIME) | |
2329 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
2330 | if (flags & MS_STRICTATIME) |
2331 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
2332 | if (flags & MS_RDONLY) |
2333 | mnt_flags |= MNT_READONLY; | |
fc33a7bb | 2334 | |
7a4dec53 | 2335 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
d0adde57 MG |
2336 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
2337 | MS_STRICTATIME); | |
1da177e4 | 2338 | |
1da177e4 | 2339 | if (flags & MS_REMOUNT) |
2d92ab3c | 2340 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
2341 | data_page); |
2342 | else if (flags & MS_BIND) | |
2d92ab3c | 2343 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 2344 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 2345 | retval = do_change_type(&path, flags); |
1da177e4 | 2346 | else if (flags & MS_MOVE) |
2d92ab3c | 2347 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 2348 | else |
2d92ab3c | 2349 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
2350 | dev_name, data_page); |
2351 | dput_out: | |
2d92ab3c | 2352 | path_put(&path); |
1da177e4 LT |
2353 | return retval; |
2354 | } | |
2355 | ||
cf8d2c11 TM |
2356 | static struct mnt_namespace *alloc_mnt_ns(void) |
2357 | { | |
2358 | struct mnt_namespace *new_ns; | |
2359 | ||
2360 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
2361 | if (!new_ns) | |
2362 | return ERR_PTR(-ENOMEM); | |
2363 | atomic_set(&new_ns->count, 1); | |
2364 | new_ns->root = NULL; | |
2365 | INIT_LIST_HEAD(&new_ns->list); | |
2366 | init_waitqueue_head(&new_ns->poll); | |
2367 | new_ns->event = 0; | |
2368 | return new_ns; | |
2369 | } | |
2370 | ||
f03c6599 AV |
2371 | void mnt_make_longterm(struct vfsmount *mnt) |
2372 | { | |
83adc753 | 2373 | __mnt_make_longterm(real_mount(mnt)); |
f03c6599 AV |
2374 | } |
2375 | ||
83adc753 | 2376 | void mnt_make_shortterm(struct vfsmount *m) |
f03c6599 | 2377 | { |
7e3d0eb0 | 2378 | #ifdef CONFIG_SMP |
83adc753 | 2379 | struct mount *mnt = real_mount(m); |
68e8a9fe | 2380 | if (atomic_add_unless(&mnt->mnt_longterm, -1, 1)) |
f03c6599 AV |
2381 | return; |
2382 | br_write_lock(vfsmount_lock); | |
68e8a9fe | 2383 | atomic_dec(&mnt->mnt_longterm); |
f03c6599 | 2384 | br_write_unlock(vfsmount_lock); |
7e3d0eb0 | 2385 | #endif |
f03c6599 AV |
2386 | } |
2387 | ||
741a2951 JD |
2388 | /* |
2389 | * Allocate a new namespace structure and populate it with contents | |
2390 | * copied from the namespace of the passed in task structure. | |
2391 | */ | |
e3222c4e | 2392 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
6b3286ed | 2393 | struct fs_struct *fs) |
1da177e4 | 2394 | { |
6b3286ed | 2395 | struct mnt_namespace *new_ns; |
7f2da1e7 | 2396 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 2397 | struct mount *p, *q; |
cb338d06 | 2398 | struct mount *new; |
1da177e4 | 2399 | |
cf8d2c11 TM |
2400 | new_ns = alloc_mnt_ns(); |
2401 | if (IS_ERR(new_ns)) | |
2402 | return new_ns; | |
1da177e4 | 2403 | |
390c6843 | 2404 | down_write(&namespace_sem); |
1da177e4 | 2405 | /* First pass: copy the tree topology */ |
87129cc0 | 2406 | new = copy_tree(real_mount(mnt_ns->root), mnt_ns->root->mnt_root, |
9676f0c6 | 2407 | CL_COPY_ALL | CL_EXPIRE); |
cb338d06 | 2408 | if (!new) { |
390c6843 | 2409 | up_write(&namespace_sem); |
1da177e4 | 2410 | kfree(new_ns); |
5cc4a034 | 2411 | return ERR_PTR(-ENOMEM); |
1da177e4 | 2412 | } |
cb338d06 | 2413 | new_ns->root = &new->mnt; |
99b7db7b | 2414 | br_write_lock(vfsmount_lock); |
1da177e4 | 2415 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); |
99b7db7b | 2416 | br_write_unlock(vfsmount_lock); |
1da177e4 LT |
2417 | |
2418 | /* | |
2419 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2420 | * as belonging to new namespace. We have already acquired a private | |
2421 | * fs_struct, so tsk->fs->lock is not needed. | |
2422 | */ | |
315fc83e | 2423 | p = real_mount(mnt_ns->root); |
cb338d06 | 2424 | q = new; |
1da177e4 | 2425 | while (p) { |
315fc83e | 2426 | q->mnt.mnt_ns = new_ns; |
83adc753 | 2427 | __mnt_make_longterm(q); |
1da177e4 | 2428 | if (fs) { |
315fc83e AV |
2429 | if (&p->mnt == fs->root.mnt) { |
2430 | fs->root.mnt = mntget(&q->mnt); | |
83adc753 | 2431 | __mnt_make_longterm(q); |
315fc83e AV |
2432 | mnt_make_shortterm(&p->mnt); |
2433 | rootmnt = &p->mnt; | |
1da177e4 | 2434 | } |
315fc83e AV |
2435 | if (&p->mnt == fs->pwd.mnt) { |
2436 | fs->pwd.mnt = mntget(&q->mnt); | |
83adc753 | 2437 | __mnt_make_longterm(q); |
315fc83e AV |
2438 | mnt_make_shortterm(&p->mnt); |
2439 | pwdmnt = &p->mnt; | |
1da177e4 | 2440 | } |
1da177e4 | 2441 | } |
6b3286ed | 2442 | p = next_mnt(p, mnt_ns->root); |
1da177e4 LT |
2443 | q = next_mnt(q, new_ns->root); |
2444 | } | |
390c6843 | 2445 | up_write(&namespace_sem); |
1da177e4 | 2446 | |
1da177e4 | 2447 | if (rootmnt) |
f03c6599 | 2448 | mntput(rootmnt); |
1da177e4 | 2449 | if (pwdmnt) |
f03c6599 | 2450 | mntput(pwdmnt); |
1da177e4 | 2451 | |
741a2951 JD |
2452 | return new_ns; |
2453 | } | |
2454 | ||
213dd266 | 2455 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
e3222c4e | 2456 | struct fs_struct *new_fs) |
741a2951 | 2457 | { |
6b3286ed | 2458 | struct mnt_namespace *new_ns; |
741a2951 | 2459 | |
e3222c4e | 2460 | BUG_ON(!ns); |
6b3286ed | 2461 | get_mnt_ns(ns); |
741a2951 JD |
2462 | |
2463 | if (!(flags & CLONE_NEWNS)) | |
e3222c4e | 2464 | return ns; |
741a2951 | 2465 | |
e3222c4e | 2466 | new_ns = dup_mnt_ns(ns, new_fs); |
741a2951 | 2467 | |
6b3286ed | 2468 | put_mnt_ns(ns); |
e3222c4e | 2469 | return new_ns; |
1da177e4 LT |
2470 | } |
2471 | ||
cf8d2c11 TM |
2472 | /** |
2473 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2474 | * @mnt: pointer to the new root filesystem mountpoint | |
2475 | */ | |
6c449c8d | 2476 | static struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt) |
cf8d2c11 TM |
2477 | { |
2478 | struct mnt_namespace *new_ns; | |
2479 | ||
2480 | new_ns = alloc_mnt_ns(); | |
2481 | if (!IS_ERR(new_ns)) { | |
2482 | mnt->mnt_ns = new_ns; | |
83adc753 | 2483 | __mnt_make_longterm(real_mount(mnt)); |
cf8d2c11 TM |
2484 | new_ns->root = mnt; |
2485 | list_add(&new_ns->list, &new_ns->root->mnt_list); | |
c1334495 AV |
2486 | } else { |
2487 | mntput(mnt); | |
cf8d2c11 TM |
2488 | } |
2489 | return new_ns; | |
2490 | } | |
cf8d2c11 | 2491 | |
ea441d11 AV |
2492 | struct dentry *mount_subtree(struct vfsmount *mnt, const char *name) |
2493 | { | |
2494 | struct mnt_namespace *ns; | |
d31da0f0 | 2495 | struct super_block *s; |
ea441d11 AV |
2496 | struct path path; |
2497 | int err; | |
2498 | ||
2499 | ns = create_mnt_ns(mnt); | |
2500 | if (IS_ERR(ns)) | |
2501 | return ERR_CAST(ns); | |
2502 | ||
2503 | err = vfs_path_lookup(mnt->mnt_root, mnt, | |
2504 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); | |
2505 | ||
2506 | put_mnt_ns(ns); | |
2507 | ||
2508 | if (err) | |
2509 | return ERR_PTR(err); | |
2510 | ||
2511 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
2512 | s = path.mnt->mnt_sb; |
2513 | atomic_inc(&s->s_active); | |
ea441d11 AV |
2514 | mntput(path.mnt); |
2515 | /* lock the sucker */ | |
d31da0f0 | 2516 | down_write(&s->s_umount); |
ea441d11 AV |
2517 | /* ... and return the root of (sub)tree on it */ |
2518 | return path.dentry; | |
2519 | } | |
2520 | EXPORT_SYMBOL(mount_subtree); | |
2521 | ||
bdc480e3 HC |
2522 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2523 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2524 | { |
eca6f534 VN |
2525 | int ret; |
2526 | char *kernel_type; | |
2527 | char *kernel_dir; | |
2528 | char *kernel_dev; | |
1da177e4 | 2529 | unsigned long data_page; |
1da177e4 | 2530 | |
eca6f534 VN |
2531 | ret = copy_mount_string(type, &kernel_type); |
2532 | if (ret < 0) | |
2533 | goto out_type; | |
1da177e4 | 2534 | |
eca6f534 VN |
2535 | kernel_dir = getname(dir_name); |
2536 | if (IS_ERR(kernel_dir)) { | |
2537 | ret = PTR_ERR(kernel_dir); | |
2538 | goto out_dir; | |
2539 | } | |
1da177e4 | 2540 | |
eca6f534 VN |
2541 | ret = copy_mount_string(dev_name, &kernel_dev); |
2542 | if (ret < 0) | |
2543 | goto out_dev; | |
1da177e4 | 2544 | |
eca6f534 VN |
2545 | ret = copy_mount_options(data, &data_page); |
2546 | if (ret < 0) | |
2547 | goto out_data; | |
1da177e4 | 2548 | |
eca6f534 VN |
2549 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
2550 | (void *) data_page); | |
1da177e4 | 2551 | |
eca6f534 VN |
2552 | free_page(data_page); |
2553 | out_data: | |
2554 | kfree(kernel_dev); | |
2555 | out_dev: | |
2556 | putname(kernel_dir); | |
2557 | out_dir: | |
2558 | kfree(kernel_type); | |
2559 | out_type: | |
2560 | return ret; | |
1da177e4 LT |
2561 | } |
2562 | ||
afac7cba AV |
2563 | /* |
2564 | * Return true if path is reachable from root | |
2565 | * | |
2566 | * namespace_sem or vfsmount_lock is held | |
2567 | */ | |
643822b4 | 2568 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
2569 | const struct path *root) |
2570 | { | |
643822b4 | 2571 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 2572 | dentry = mnt->mnt_mountpoint; |
0714a533 | 2573 | mnt = mnt->mnt_parent; |
afac7cba | 2574 | } |
643822b4 | 2575 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
2576 | } |
2577 | ||
2578 | int path_is_under(struct path *path1, struct path *path2) | |
2579 | { | |
2580 | int res; | |
2581 | br_read_lock(vfsmount_lock); | |
643822b4 | 2582 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
afac7cba AV |
2583 | br_read_unlock(vfsmount_lock); |
2584 | return res; | |
2585 | } | |
2586 | EXPORT_SYMBOL(path_is_under); | |
2587 | ||
1da177e4 LT |
2588 | /* |
2589 | * pivot_root Semantics: | |
2590 | * Moves the root file system of the current process to the directory put_old, | |
2591 | * makes new_root as the new root file system of the current process, and sets | |
2592 | * root/cwd of all processes which had them on the current root to new_root. | |
2593 | * | |
2594 | * Restrictions: | |
2595 | * The new_root and put_old must be directories, and must not be on the | |
2596 | * same file system as the current process root. The put_old must be | |
2597 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2598 | * pointed to by put_old must yield the same directory as new_root. No other | |
2599 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2600 | * | |
4a0d11fa NB |
2601 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2602 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2603 | * in this situation. | |
2604 | * | |
1da177e4 LT |
2605 | * Notes: |
2606 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2607 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2608 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2609 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2610 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2611 | * first. | |
2612 | */ | |
3480b257 HC |
2613 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2614 | const char __user *, put_old) | |
1da177e4 | 2615 | { |
2d8f3038 | 2616 | struct path new, old, parent_path, root_parent, root; |
419148da | 2617 | struct mount *new_mnt, *root_mnt; |
1da177e4 LT |
2618 | int error; |
2619 | ||
2620 | if (!capable(CAP_SYS_ADMIN)) | |
2621 | return -EPERM; | |
2622 | ||
2d8f3038 | 2623 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2624 | if (error) |
2625 | goto out0; | |
1da177e4 | 2626 | |
2d8f3038 | 2627 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2628 | if (error) |
2629 | goto out1; | |
2630 | ||
2d8f3038 | 2631 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
2632 | if (error) |
2633 | goto out2; | |
1da177e4 | 2634 | |
f7ad3c6b | 2635 | get_fs_root(current->fs, &root); |
b12cea91 AV |
2636 | error = lock_mount(&old); |
2637 | if (error) | |
2638 | goto out3; | |
2639 | ||
1da177e4 | 2640 | error = -EINVAL; |
419148da AV |
2641 | new_mnt = real_mount(new.mnt); |
2642 | root_mnt = real_mount(root.mnt); | |
2d8f3038 | 2643 | if (IS_MNT_SHARED(old.mnt) || |
0714a533 AV |
2644 | IS_MNT_SHARED(&new_mnt->mnt_parent->mnt) || |
2645 | IS_MNT_SHARED(&root_mnt->mnt_parent->mnt)) | |
b12cea91 | 2646 | goto out4; |
27cb1572 | 2647 | if (!check_mnt(root.mnt) || !check_mnt(new.mnt)) |
b12cea91 | 2648 | goto out4; |
1da177e4 | 2649 | error = -ENOENT; |
f3da392e | 2650 | if (d_unlinked(new.dentry)) |
b12cea91 | 2651 | goto out4; |
f3da392e | 2652 | if (d_unlinked(old.dentry)) |
b12cea91 | 2653 | goto out4; |
1da177e4 | 2654 | error = -EBUSY; |
2d8f3038 AV |
2655 | if (new.mnt == root.mnt || |
2656 | old.mnt == root.mnt) | |
b12cea91 | 2657 | goto out4; /* loop, on the same file system */ |
1da177e4 | 2658 | error = -EINVAL; |
8c3ee42e | 2659 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 2660 | goto out4; /* not a mountpoint */ |
676da58d | 2661 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 2662 | goto out4; /* not attached */ |
2d8f3038 | 2663 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 2664 | goto out4; /* not a mountpoint */ |
676da58d | 2665 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 2666 | goto out4; /* not attached */ |
4ac91378 | 2667 | /* make sure we can reach put_old from new_root */ |
643822b4 | 2668 | if (!is_path_reachable(real_mount(old.mnt), old.dentry, &new)) |
b12cea91 | 2669 | goto out4; |
27cb1572 | 2670 | br_write_lock(vfsmount_lock); |
419148da AV |
2671 | detach_mnt(new_mnt, &parent_path); |
2672 | detach_mnt(root_mnt, &root_parent); | |
4ac91378 | 2673 | /* mount old root on put_old */ |
419148da | 2674 | attach_mnt(root_mnt, &old); |
4ac91378 | 2675 | /* mount new_root on / */ |
419148da | 2676 | attach_mnt(new_mnt, &root_parent); |
6b3286ed | 2677 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
99b7db7b | 2678 | br_write_unlock(vfsmount_lock); |
2d8f3038 | 2679 | chroot_fs_refs(&root, &new); |
1da177e4 | 2680 | error = 0; |
b12cea91 AV |
2681 | out4: |
2682 | unlock_mount(&old); | |
2683 | if (!error) { | |
2684 | path_put(&root_parent); | |
2685 | path_put(&parent_path); | |
2686 | } | |
2687 | out3: | |
8c3ee42e | 2688 | path_put(&root); |
b12cea91 | 2689 | out2: |
2d8f3038 | 2690 | path_put(&old); |
1da177e4 | 2691 | out1: |
2d8f3038 | 2692 | path_put(&new); |
1da177e4 | 2693 | out0: |
1da177e4 | 2694 | return error; |
1da177e4 LT |
2695 | } |
2696 | ||
2697 | static void __init init_mount_tree(void) | |
2698 | { | |
2699 | struct vfsmount *mnt; | |
6b3286ed | 2700 | struct mnt_namespace *ns; |
ac748a09 | 2701 | struct path root; |
1da177e4 LT |
2702 | |
2703 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
2704 | if (IS_ERR(mnt)) | |
2705 | panic("Can't create rootfs"); | |
b3e19d92 | 2706 | |
3b22edc5 TM |
2707 | ns = create_mnt_ns(mnt); |
2708 | if (IS_ERR(ns)) | |
1da177e4 | 2709 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
2710 | |
2711 | init_task.nsproxy->mnt_ns = ns; | |
2712 | get_mnt_ns(ns); | |
2713 | ||
ac748a09 JB |
2714 | root.mnt = ns->root; |
2715 | root.dentry = ns->root->mnt_root; | |
2716 | ||
2717 | set_fs_pwd(current->fs, &root); | |
2718 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
2719 | } |
2720 | ||
74bf17cf | 2721 | void __init mnt_init(void) |
1da177e4 | 2722 | { |
13f14b4d | 2723 | unsigned u; |
15a67dd8 | 2724 | int err; |
1da177e4 | 2725 | |
390c6843 RP |
2726 | init_rwsem(&namespace_sem); |
2727 | ||
7d6fec45 | 2728 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
20c2df83 | 2729 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 2730 | |
b58fed8b | 2731 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
2732 | |
2733 | if (!mount_hashtable) | |
2734 | panic("Failed to allocate mount hash table\n"); | |
2735 | ||
80cdc6da | 2736 | printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE); |
13f14b4d ED |
2737 | |
2738 | for (u = 0; u < HASH_SIZE; u++) | |
2739 | INIT_LIST_HEAD(&mount_hashtable[u]); | |
1da177e4 | 2740 | |
99b7db7b NP |
2741 | br_lock_init(vfsmount_lock); |
2742 | ||
15a67dd8 RD |
2743 | err = sysfs_init(); |
2744 | if (err) | |
2745 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 2746 | __func__, err); |
00d26666 GKH |
2747 | fs_kobj = kobject_create_and_add("fs", NULL); |
2748 | if (!fs_kobj) | |
8e24eea7 | 2749 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
2750 | init_rootfs(); |
2751 | init_mount_tree(); | |
2752 | } | |
2753 | ||
616511d0 | 2754 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 2755 | { |
70fbcdf4 | 2756 | LIST_HEAD(umount_list); |
616511d0 | 2757 | |
d498b25a | 2758 | if (!atomic_dec_and_test(&ns->count)) |
616511d0 | 2759 | return; |
390c6843 | 2760 | down_write(&namespace_sem); |
99b7db7b | 2761 | br_write_lock(vfsmount_lock); |
761d5c38 | 2762 | umount_tree(real_mount(ns->root), 0, &umount_list); |
99b7db7b | 2763 | br_write_unlock(vfsmount_lock); |
390c6843 | 2764 | up_write(&namespace_sem); |
70fbcdf4 | 2765 | release_mounts(&umount_list); |
6b3286ed | 2766 | kfree(ns); |
1da177e4 | 2767 | } |
9d412a43 AV |
2768 | |
2769 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) | |
2770 | { | |
423e0ab0 TC |
2771 | struct vfsmount *mnt; |
2772 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); | |
2773 | if (!IS_ERR(mnt)) { | |
2774 | /* | |
2775 | * it is a longterm mount, don't release mnt until | |
2776 | * we unmount before file sys is unregistered | |
2777 | */ | |
2778 | mnt_make_longterm(mnt); | |
2779 | } | |
2780 | return mnt; | |
9d412a43 AV |
2781 | } |
2782 | EXPORT_SYMBOL_GPL(kern_mount_data); | |
423e0ab0 TC |
2783 | |
2784 | void kern_unmount(struct vfsmount *mnt) | |
2785 | { | |
2786 | /* release long term mount so mount point can be released */ | |
2787 | if (!IS_ERR_OR_NULL(mnt)) { | |
2788 | mnt_make_shortterm(mnt); | |
2789 | mntput(mnt); | |
2790 | } | |
2791 | } | |
2792 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 AV |
2793 | |
2794 | bool our_mnt(struct vfsmount *mnt) | |
2795 | { | |
2796 | return check_mnt(mnt); | |
2797 | } |