Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/namespace.c | |
3 | * | |
4 | * (C) Copyright Al Viro 2000, 2001 | |
5 | * Released under GPL v2. | |
6 | * | |
7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. | |
8 | * Heavily rewritten. | |
9 | */ | |
10 | ||
1da177e4 LT |
11 | #include <linux/syscalls.h> |
12 | #include <linux/slab.h> | |
13 | #include <linux/sched.h> | |
14 | #include <linux/smp_lock.h> | |
15 | #include <linux/init.h> | |
15a67dd8 | 16 | #include <linux/kernel.h> |
1da177e4 | 17 | #include <linux/acct.h> |
16f7e0fe | 18 | #include <linux/capability.h> |
3d733633 | 19 | #include <linux/cpumask.h> |
1da177e4 | 20 | #include <linux/module.h> |
f20a9ead | 21 | #include <linux/sysfs.h> |
1da177e4 | 22 | #include <linux/seq_file.h> |
6b3286ed | 23 | #include <linux/mnt_namespace.h> |
1da177e4 | 24 | #include <linux/namei.h> |
b43f3cbd | 25 | #include <linux/nsproxy.h> |
1da177e4 LT |
26 | #include <linux/security.h> |
27 | #include <linux/mount.h> | |
07f3f05c | 28 | #include <linux/ramfs.h> |
13f14b4d | 29 | #include <linux/log2.h> |
73cd49ec | 30 | #include <linux/idr.h> |
5ad4e53b | 31 | #include <linux/fs_struct.h> |
1da177e4 LT |
32 | #include <asm/uaccess.h> |
33 | #include <asm/unistd.h> | |
07b20889 | 34 | #include "pnode.h" |
948730b0 | 35 | #include "internal.h" |
1da177e4 | 36 | |
13f14b4d ED |
37 | #define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) |
38 | #define HASH_SIZE (1UL << HASH_SHIFT) | |
39 | ||
1da177e4 | 40 | /* spinlock for vfsmount related operations, inplace of dcache_lock */ |
5addc5dd AV |
41 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); |
42 | ||
43 | static int event; | |
73cd49ec | 44 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 45 | static DEFINE_IDA(mnt_group_ida); |
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 | |
1da177e4 LT |
57 | static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) |
58 | { | |
b58fed8b RP |
59 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
60 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
13f14b4d ED |
61 | tmp = tmp + (tmp >> HASH_SHIFT); |
62 | return tmp & (HASH_SIZE - 1); | |
1da177e4 LT |
63 | } |
64 | ||
3d733633 DH |
65 | #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) |
66 | ||
73cd49ec MS |
67 | /* allocation is serialized by namespace_sem */ |
68 | static int mnt_alloc_id(struct vfsmount *mnt) | |
69 | { | |
70 | int res; | |
71 | ||
72 | retry: | |
73 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); | |
74 | spin_lock(&vfsmount_lock); | |
f21f6220 AV |
75 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
76 | if (!res) | |
77 | mnt_id_start = mnt->mnt_id + 1; | |
73cd49ec MS |
78 | spin_unlock(&vfsmount_lock); |
79 | if (res == -EAGAIN) | |
80 | goto retry; | |
81 | ||
82 | return res; | |
83 | } | |
84 | ||
85 | static void mnt_free_id(struct vfsmount *mnt) | |
86 | { | |
f21f6220 | 87 | int id = mnt->mnt_id; |
73cd49ec | 88 | spin_lock(&vfsmount_lock); |
f21f6220 AV |
89 | ida_remove(&mnt_id_ida, id); |
90 | if (mnt_id_start > id) | |
91 | mnt_id_start = id; | |
73cd49ec MS |
92 | spin_unlock(&vfsmount_lock); |
93 | } | |
94 | ||
719f5d7f MS |
95 | /* |
96 | * Allocate a new peer group ID | |
97 | * | |
98 | * mnt_group_ida is protected by namespace_sem | |
99 | */ | |
100 | static int mnt_alloc_group_id(struct vfsmount *mnt) | |
101 | { | |
f21f6220 AV |
102 | int res; |
103 | ||
719f5d7f MS |
104 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
105 | return -ENOMEM; | |
106 | ||
f21f6220 AV |
107 | res = ida_get_new_above(&mnt_group_ida, |
108 | mnt_group_start, | |
109 | &mnt->mnt_group_id); | |
110 | if (!res) | |
111 | mnt_group_start = mnt->mnt_group_id + 1; | |
112 | ||
113 | return res; | |
719f5d7f MS |
114 | } |
115 | ||
116 | /* | |
117 | * Release a peer group ID | |
118 | */ | |
119 | void mnt_release_group_id(struct vfsmount *mnt) | |
120 | { | |
f21f6220 AV |
121 | int id = mnt->mnt_group_id; |
122 | ida_remove(&mnt_group_ida, id); | |
123 | if (mnt_group_start > id) | |
124 | mnt_group_start = id; | |
719f5d7f MS |
125 | mnt->mnt_group_id = 0; |
126 | } | |
127 | ||
1da177e4 LT |
128 | struct vfsmount *alloc_vfsmnt(const char *name) |
129 | { | |
c3762229 | 130 | struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
1da177e4 | 131 | if (mnt) { |
73cd49ec MS |
132 | int err; |
133 | ||
134 | err = mnt_alloc_id(mnt); | |
88b38782 LZ |
135 | if (err) |
136 | goto out_free_cache; | |
137 | ||
138 | if (name) { | |
139 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); | |
140 | if (!mnt->mnt_devname) | |
141 | goto out_free_id; | |
73cd49ec MS |
142 | } |
143 | ||
b58fed8b | 144 | atomic_set(&mnt->mnt_count, 1); |
1da177e4 LT |
145 | INIT_LIST_HEAD(&mnt->mnt_hash); |
146 | INIT_LIST_HEAD(&mnt->mnt_child); | |
147 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
148 | INIT_LIST_HEAD(&mnt->mnt_list); | |
55e700b9 | 149 | INIT_LIST_HEAD(&mnt->mnt_expire); |
03e06e68 | 150 | INIT_LIST_HEAD(&mnt->mnt_share); |
a58b0eb8 RP |
151 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
152 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
d3ef3d73 | 153 | #ifdef CONFIG_SMP |
154 | mnt->mnt_writers = alloc_percpu(int); | |
155 | if (!mnt->mnt_writers) | |
156 | goto out_free_devname; | |
157 | #else | |
158 | mnt->mnt_writers = 0; | |
159 | #endif | |
1da177e4 LT |
160 | } |
161 | return mnt; | |
88b38782 | 162 | |
d3ef3d73 | 163 | #ifdef CONFIG_SMP |
164 | out_free_devname: | |
165 | kfree(mnt->mnt_devname); | |
166 | #endif | |
88b38782 LZ |
167 | out_free_id: |
168 | mnt_free_id(mnt); | |
169 | out_free_cache: | |
170 | kmem_cache_free(mnt_cache, mnt); | |
171 | return NULL; | |
1da177e4 LT |
172 | } |
173 | ||
3d733633 DH |
174 | /* |
175 | * Most r/o checks on a fs are for operations that take | |
176 | * discrete amounts of time, like a write() or unlink(). | |
177 | * We must keep track of when those operations start | |
178 | * (for permission checks) and when they end, so that | |
179 | * we can determine when writes are able to occur to | |
180 | * a filesystem. | |
181 | */ | |
182 | /* | |
183 | * __mnt_is_readonly: check whether a mount is read-only | |
184 | * @mnt: the mount to check for its write status | |
185 | * | |
186 | * This shouldn't be used directly ouside of the VFS. | |
187 | * It does not guarantee that the filesystem will stay | |
188 | * r/w, just that it is right *now*. This can not and | |
189 | * should not be used in place of IS_RDONLY(inode). | |
190 | * mnt_want/drop_write() will _keep_ the filesystem | |
191 | * r/w. | |
192 | */ | |
193 | int __mnt_is_readonly(struct vfsmount *mnt) | |
194 | { | |
2e4b7fcd DH |
195 | if (mnt->mnt_flags & MNT_READONLY) |
196 | return 1; | |
197 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
198 | return 1; | |
199 | return 0; | |
3d733633 DH |
200 | } |
201 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
202 | ||
d3ef3d73 | 203 | static inline void inc_mnt_writers(struct vfsmount *mnt) |
204 | { | |
205 | #ifdef CONFIG_SMP | |
206 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++; | |
207 | #else | |
208 | mnt->mnt_writers++; | |
209 | #endif | |
210 | } | |
3d733633 | 211 | |
d3ef3d73 | 212 | static inline void dec_mnt_writers(struct vfsmount *mnt) |
3d733633 | 213 | { |
d3ef3d73 | 214 | #ifdef CONFIG_SMP |
215 | (*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--; | |
216 | #else | |
217 | mnt->mnt_writers--; | |
218 | #endif | |
3d733633 | 219 | } |
3d733633 | 220 | |
d3ef3d73 | 221 | static unsigned int count_mnt_writers(struct vfsmount *mnt) |
3d733633 | 222 | { |
d3ef3d73 | 223 | #ifdef CONFIG_SMP |
224 | unsigned int count = 0; | |
3d733633 | 225 | int cpu; |
3d733633 DH |
226 | |
227 | for_each_possible_cpu(cpu) { | |
d3ef3d73 | 228 | count += *per_cpu_ptr(mnt->mnt_writers, cpu); |
3d733633 | 229 | } |
3d733633 | 230 | |
d3ef3d73 | 231 | return count; |
232 | #else | |
233 | return mnt->mnt_writers; | |
234 | #endif | |
3d733633 DH |
235 | } |
236 | ||
8366025e DH |
237 | /* |
238 | * Most r/o checks on a fs are for operations that take | |
239 | * discrete amounts of time, like a write() or unlink(). | |
240 | * We must keep track of when those operations start | |
241 | * (for permission checks) and when they end, so that | |
242 | * we can determine when writes are able to occur to | |
243 | * a filesystem. | |
244 | */ | |
245 | /** | |
246 | * mnt_want_write - get write access to a mount | |
247 | * @mnt: the mount on which to take a write | |
248 | * | |
249 | * This tells the low-level filesystem that a write is | |
250 | * about to be performed to it, and makes sure that | |
251 | * writes are allowed before returning success. When | |
252 | * the write operation is finished, mnt_drop_write() | |
253 | * must be called. This is effectively a refcount. | |
254 | */ | |
255 | int mnt_want_write(struct vfsmount *mnt) | |
256 | { | |
3d733633 | 257 | int ret = 0; |
3d733633 | 258 | |
d3ef3d73 | 259 | preempt_disable(); |
260 | inc_mnt_writers(mnt); | |
261 | /* | |
262 | * The store to inc_mnt_writers must be visible before we pass | |
263 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our | |
264 | * incremented count after it has set MNT_WRITE_HOLD. | |
265 | */ | |
266 | smp_mb(); | |
267 | while (mnt->mnt_flags & MNT_WRITE_HOLD) | |
268 | cpu_relax(); | |
269 | /* | |
270 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
271 | * be set to match its requirements. So we must not load that until | |
272 | * MNT_WRITE_HOLD is cleared. | |
273 | */ | |
274 | smp_rmb(); | |
3d733633 | 275 | if (__mnt_is_readonly(mnt)) { |
d3ef3d73 | 276 | dec_mnt_writers(mnt); |
3d733633 DH |
277 | ret = -EROFS; |
278 | goto out; | |
279 | } | |
3d733633 | 280 | out: |
d3ef3d73 | 281 | preempt_enable(); |
3d733633 | 282 | return ret; |
8366025e DH |
283 | } |
284 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
285 | ||
96029c4e | 286 | /** |
287 | * mnt_clone_write - get write access to a mount | |
288 | * @mnt: the mount on which to take a write | |
289 | * | |
290 | * This is effectively like mnt_want_write, except | |
291 | * it must only be used to take an extra write reference | |
292 | * on a mountpoint that we already know has a write reference | |
293 | * on it. This allows some optimisation. | |
294 | * | |
295 | * After finished, mnt_drop_write must be called as usual to | |
296 | * drop the reference. | |
297 | */ | |
298 | int mnt_clone_write(struct vfsmount *mnt) | |
299 | { | |
300 | /* superblock may be r/o */ | |
301 | if (__mnt_is_readonly(mnt)) | |
302 | return -EROFS; | |
303 | preempt_disable(); | |
304 | inc_mnt_writers(mnt); | |
305 | preempt_enable(); | |
306 | return 0; | |
307 | } | |
308 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
309 | ||
310 | /** | |
311 | * mnt_want_write_file - get write access to a file's mount | |
312 | * @file: the file who's mount on which to take a write | |
313 | * | |
314 | * This is like mnt_want_write, but it takes a file and can | |
315 | * do some optimisations if the file is open for write already | |
316 | */ | |
317 | int mnt_want_write_file(struct file *file) | |
318 | { | |
2d8dd38a OH |
319 | struct inode *inode = file->f_dentry->d_inode; |
320 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) | |
96029c4e | 321 | return mnt_want_write(file->f_path.mnt); |
322 | else | |
323 | return mnt_clone_write(file->f_path.mnt); | |
324 | } | |
325 | EXPORT_SYMBOL_GPL(mnt_want_write_file); | |
326 | ||
8366025e DH |
327 | /** |
328 | * mnt_drop_write - give up write access to a mount | |
329 | * @mnt: the mount on which to give up write access | |
330 | * | |
331 | * Tells the low-level filesystem that we are done | |
332 | * performing writes to it. Must be matched with | |
333 | * mnt_want_write() call above. | |
334 | */ | |
335 | void mnt_drop_write(struct vfsmount *mnt) | |
336 | { | |
d3ef3d73 | 337 | preempt_disable(); |
338 | dec_mnt_writers(mnt); | |
339 | preempt_enable(); | |
8366025e DH |
340 | } |
341 | EXPORT_SYMBOL_GPL(mnt_drop_write); | |
342 | ||
2e4b7fcd | 343 | static int mnt_make_readonly(struct vfsmount *mnt) |
8366025e | 344 | { |
3d733633 DH |
345 | int ret = 0; |
346 | ||
d3ef3d73 | 347 | spin_lock(&vfsmount_lock); |
348 | mnt->mnt_flags |= MNT_WRITE_HOLD; | |
3d733633 | 349 | /* |
d3ef3d73 | 350 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
351 | * should be visible before we do. | |
3d733633 | 352 | */ |
d3ef3d73 | 353 | smp_mb(); |
354 | ||
3d733633 | 355 | /* |
d3ef3d73 | 356 | * With writers on hold, if this value is zero, then there are |
357 | * definitely no active writers (although held writers may subsequently | |
358 | * increment the count, they'll have to wait, and decrement it after | |
359 | * seeing MNT_READONLY). | |
360 | * | |
361 | * It is OK to have counter incremented on one CPU and decremented on | |
362 | * another: the sum will add up correctly. The danger would be when we | |
363 | * sum up each counter, if we read a counter before it is incremented, | |
364 | * but then read another CPU's count which it has been subsequently | |
365 | * decremented from -- we would see more decrements than we should. | |
366 | * MNT_WRITE_HOLD protects against this scenario, because | |
367 | * mnt_want_write first increments count, then smp_mb, then spins on | |
368 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
369 | * we're counting up here. | |
3d733633 | 370 | */ |
d3ef3d73 | 371 | if (count_mnt_writers(mnt) > 0) |
372 | ret = -EBUSY; | |
373 | else | |
2e4b7fcd | 374 | mnt->mnt_flags |= MNT_READONLY; |
d3ef3d73 | 375 | /* |
376 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
377 | * that become unheld will see MNT_READONLY. | |
378 | */ | |
379 | smp_wmb(); | |
380 | mnt->mnt_flags &= ~MNT_WRITE_HOLD; | |
2e4b7fcd | 381 | spin_unlock(&vfsmount_lock); |
3d733633 | 382 | return ret; |
8366025e | 383 | } |
8366025e | 384 | |
2e4b7fcd DH |
385 | static void __mnt_unmake_readonly(struct vfsmount *mnt) |
386 | { | |
387 | spin_lock(&vfsmount_lock); | |
388 | mnt->mnt_flags &= ~MNT_READONLY; | |
389 | spin_unlock(&vfsmount_lock); | |
390 | } | |
391 | ||
a3ec947c | 392 | void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb) |
454e2398 DH |
393 | { |
394 | mnt->mnt_sb = sb; | |
395 | mnt->mnt_root = dget(sb->s_root); | |
454e2398 DH |
396 | } |
397 | ||
398 | EXPORT_SYMBOL(simple_set_mnt); | |
399 | ||
1da177e4 LT |
400 | void free_vfsmnt(struct vfsmount *mnt) |
401 | { | |
402 | kfree(mnt->mnt_devname); | |
73cd49ec | 403 | mnt_free_id(mnt); |
d3ef3d73 | 404 | #ifdef CONFIG_SMP |
405 | free_percpu(mnt->mnt_writers); | |
406 | #endif | |
1da177e4 LT |
407 | kmem_cache_free(mnt_cache, mnt); |
408 | } | |
409 | ||
410 | /* | |
a05964f3 RP |
411 | * find the first or last mount at @dentry on vfsmount @mnt depending on |
412 | * @dir. If @dir is set return the first mount else return the last mount. | |
1da177e4 | 413 | */ |
a05964f3 RP |
414 | struct vfsmount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, |
415 | int dir) | |
1da177e4 | 416 | { |
b58fed8b RP |
417 | struct list_head *head = mount_hashtable + hash(mnt, dentry); |
418 | struct list_head *tmp = head; | |
1da177e4 LT |
419 | struct vfsmount *p, *found = NULL; |
420 | ||
1da177e4 | 421 | for (;;) { |
a05964f3 | 422 | tmp = dir ? tmp->next : tmp->prev; |
1da177e4 LT |
423 | p = NULL; |
424 | if (tmp == head) | |
425 | break; | |
426 | p = list_entry(tmp, struct vfsmount, mnt_hash); | |
427 | if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) { | |
a05964f3 | 428 | found = p; |
1da177e4 LT |
429 | break; |
430 | } | |
431 | } | |
1da177e4 LT |
432 | return found; |
433 | } | |
434 | ||
a05964f3 RP |
435 | /* |
436 | * lookup_mnt increments the ref count before returning | |
437 | * the vfsmount struct. | |
438 | */ | |
1c755af4 | 439 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 RP |
440 | { |
441 | struct vfsmount *child_mnt; | |
442 | spin_lock(&vfsmount_lock); | |
1c755af4 | 443 | if ((child_mnt = __lookup_mnt(path->mnt, path->dentry, 1))) |
a05964f3 RP |
444 | mntget(child_mnt); |
445 | spin_unlock(&vfsmount_lock); | |
446 | return child_mnt; | |
447 | } | |
448 | ||
1da177e4 LT |
449 | static inline int check_mnt(struct vfsmount *mnt) |
450 | { | |
6b3286ed | 451 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
452 | } |
453 | ||
6b3286ed | 454 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
455 | { |
456 | if (ns) { | |
457 | ns->event = ++event; | |
458 | wake_up_interruptible(&ns->poll); | |
459 | } | |
460 | } | |
461 | ||
6b3286ed | 462 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
463 | { |
464 | if (ns && ns->event != event) { | |
465 | ns->event = event; | |
466 | wake_up_interruptible(&ns->poll); | |
467 | } | |
468 | } | |
469 | ||
1a390689 | 470 | static void detach_mnt(struct vfsmount *mnt, struct path *old_path) |
1da177e4 | 471 | { |
1a390689 AV |
472 | old_path->dentry = mnt->mnt_mountpoint; |
473 | old_path->mnt = mnt->mnt_parent; | |
1da177e4 LT |
474 | mnt->mnt_parent = mnt; |
475 | mnt->mnt_mountpoint = mnt->mnt_root; | |
476 | list_del_init(&mnt->mnt_child); | |
477 | list_del_init(&mnt->mnt_hash); | |
1a390689 | 478 | old_path->dentry->d_mounted--; |
1da177e4 LT |
479 | } |
480 | ||
b90fa9ae RP |
481 | void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, |
482 | struct vfsmount *child_mnt) | |
483 | { | |
484 | child_mnt->mnt_parent = mntget(mnt); | |
485 | child_mnt->mnt_mountpoint = dget(dentry); | |
486 | dentry->d_mounted++; | |
487 | } | |
488 | ||
1a390689 | 489 | static void attach_mnt(struct vfsmount *mnt, struct path *path) |
1da177e4 | 490 | { |
1a390689 | 491 | mnt_set_mountpoint(path->mnt, path->dentry, mnt); |
b90fa9ae | 492 | list_add_tail(&mnt->mnt_hash, mount_hashtable + |
1a390689 AV |
493 | hash(path->mnt, path->dentry)); |
494 | list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); | |
b90fa9ae RP |
495 | } |
496 | ||
497 | /* | |
498 | * the caller must hold vfsmount_lock | |
499 | */ | |
500 | static void commit_tree(struct vfsmount *mnt) | |
501 | { | |
502 | struct vfsmount *parent = mnt->mnt_parent; | |
503 | struct vfsmount *m; | |
504 | LIST_HEAD(head); | |
6b3286ed | 505 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae RP |
506 | |
507 | BUG_ON(parent == mnt); | |
508 | ||
509 | list_add_tail(&head, &mnt->mnt_list); | |
510 | list_for_each_entry(m, &head, mnt_list) | |
6b3286ed | 511 | m->mnt_ns = n; |
b90fa9ae RP |
512 | list_splice(&head, n->list.prev); |
513 | ||
514 | list_add_tail(&mnt->mnt_hash, mount_hashtable + | |
515 | hash(parent, mnt->mnt_mountpoint)); | |
516 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
6b3286ed | 517 | touch_mnt_namespace(n); |
1da177e4 LT |
518 | } |
519 | ||
520 | static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root) | |
521 | { | |
522 | struct list_head *next = p->mnt_mounts.next; | |
523 | if (next == &p->mnt_mounts) { | |
524 | while (1) { | |
525 | if (p == root) | |
526 | return NULL; | |
527 | next = p->mnt_child.next; | |
528 | if (next != &p->mnt_parent->mnt_mounts) | |
529 | break; | |
530 | p = p->mnt_parent; | |
531 | } | |
532 | } | |
533 | return list_entry(next, struct vfsmount, mnt_child); | |
534 | } | |
535 | ||
9676f0c6 RP |
536 | static struct vfsmount *skip_mnt_tree(struct vfsmount *p) |
537 | { | |
538 | struct list_head *prev = p->mnt_mounts.prev; | |
539 | while (prev != &p->mnt_mounts) { | |
540 | p = list_entry(prev, struct vfsmount, mnt_child); | |
541 | prev = p->mnt_mounts.prev; | |
542 | } | |
543 | return p; | |
544 | } | |
545 | ||
36341f64 RP |
546 | static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, |
547 | int flag) | |
1da177e4 LT |
548 | { |
549 | struct super_block *sb = old->mnt_sb; | |
550 | struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); | |
551 | ||
552 | if (mnt) { | |
719f5d7f MS |
553 | if (flag & (CL_SLAVE | CL_PRIVATE)) |
554 | mnt->mnt_group_id = 0; /* not a peer of original */ | |
555 | else | |
556 | mnt->mnt_group_id = old->mnt_group_id; | |
557 | ||
558 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { | |
559 | int err = mnt_alloc_group_id(mnt); | |
560 | if (err) | |
561 | goto out_free; | |
562 | } | |
563 | ||
1da177e4 LT |
564 | mnt->mnt_flags = old->mnt_flags; |
565 | atomic_inc(&sb->s_active); | |
566 | mnt->mnt_sb = sb; | |
567 | mnt->mnt_root = dget(root); | |
568 | mnt->mnt_mountpoint = mnt->mnt_root; | |
569 | mnt->mnt_parent = mnt; | |
b90fa9ae | 570 | |
5afe0022 RP |
571 | if (flag & CL_SLAVE) { |
572 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); | |
573 | mnt->mnt_master = old; | |
574 | CLEAR_MNT_SHARED(mnt); | |
8aec0809 | 575 | } else if (!(flag & CL_PRIVATE)) { |
5afe0022 RP |
576 | if ((flag & CL_PROPAGATION) || IS_MNT_SHARED(old)) |
577 | list_add(&mnt->mnt_share, &old->mnt_share); | |
578 | if (IS_MNT_SLAVE(old)) | |
579 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
580 | mnt->mnt_master = old->mnt_master; | |
581 | } | |
b90fa9ae RP |
582 | if (flag & CL_MAKE_SHARED) |
583 | set_mnt_shared(mnt); | |
1da177e4 LT |
584 | |
585 | /* stick the duplicate mount on the same expiry list | |
586 | * as the original if that was on one */ | |
36341f64 | 587 | if (flag & CL_EXPIRE) { |
36341f64 RP |
588 | if (!list_empty(&old->mnt_expire)) |
589 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
36341f64 | 590 | } |
1da177e4 LT |
591 | } |
592 | return mnt; | |
719f5d7f MS |
593 | |
594 | out_free: | |
595 | free_vfsmnt(mnt); | |
596 | return NULL; | |
1da177e4 LT |
597 | } |
598 | ||
7b7b1ace | 599 | static inline void __mntput(struct vfsmount *mnt) |
1da177e4 LT |
600 | { |
601 | struct super_block *sb = mnt->mnt_sb; | |
3d733633 DH |
602 | /* |
603 | * This probably indicates that somebody messed | |
604 | * up a mnt_want/drop_write() pair. If this | |
605 | * happens, the filesystem was probably unable | |
606 | * to make r/w->r/o transitions. | |
607 | */ | |
d3ef3d73 | 608 | /* |
609 | * atomic_dec_and_lock() used to deal with ->mnt_count decrements | |
610 | * provides barriers, so count_mnt_writers() below is safe. AV | |
611 | */ | |
612 | WARN_ON(count_mnt_writers(mnt)); | |
1da177e4 LT |
613 | dput(mnt->mnt_root); |
614 | free_vfsmnt(mnt); | |
615 | deactivate_super(sb); | |
616 | } | |
617 | ||
7b7b1ace AV |
618 | void mntput_no_expire(struct vfsmount *mnt) |
619 | { | |
620 | repeat: | |
621 | if (atomic_dec_and_lock(&mnt->mnt_count, &vfsmount_lock)) { | |
622 | if (likely(!mnt->mnt_pinned)) { | |
623 | spin_unlock(&vfsmount_lock); | |
624 | __mntput(mnt); | |
625 | return; | |
626 | } | |
627 | atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count); | |
628 | mnt->mnt_pinned = 0; | |
629 | spin_unlock(&vfsmount_lock); | |
630 | acct_auto_close_mnt(mnt); | |
631 | security_sb_umount_close(mnt); | |
632 | goto repeat; | |
633 | } | |
634 | } | |
635 | ||
636 | EXPORT_SYMBOL(mntput_no_expire); | |
637 | ||
638 | void mnt_pin(struct vfsmount *mnt) | |
639 | { | |
640 | spin_lock(&vfsmount_lock); | |
641 | mnt->mnt_pinned++; | |
642 | spin_unlock(&vfsmount_lock); | |
643 | } | |
644 | ||
645 | EXPORT_SYMBOL(mnt_pin); | |
646 | ||
647 | void mnt_unpin(struct vfsmount *mnt) | |
648 | { | |
649 | spin_lock(&vfsmount_lock); | |
650 | if (mnt->mnt_pinned) { | |
651 | atomic_inc(&mnt->mnt_count); | |
652 | mnt->mnt_pinned--; | |
653 | } | |
654 | spin_unlock(&vfsmount_lock); | |
655 | } | |
656 | ||
657 | EXPORT_SYMBOL(mnt_unpin); | |
1da177e4 | 658 | |
b3b304a2 MS |
659 | static inline void mangle(struct seq_file *m, const char *s) |
660 | { | |
661 | seq_escape(m, s, " \t\n\\"); | |
662 | } | |
663 | ||
664 | /* | |
665 | * Simple .show_options callback for filesystems which don't want to | |
666 | * implement more complex mount option showing. | |
667 | * | |
668 | * See also save_mount_options(). | |
669 | */ | |
670 | int generic_show_options(struct seq_file *m, struct vfsmount *mnt) | |
671 | { | |
2a32cebd AV |
672 | const char *options; |
673 | ||
674 | rcu_read_lock(); | |
675 | options = rcu_dereference(mnt->mnt_sb->s_options); | |
b3b304a2 MS |
676 | |
677 | if (options != NULL && options[0]) { | |
678 | seq_putc(m, ','); | |
679 | mangle(m, options); | |
680 | } | |
2a32cebd | 681 | rcu_read_unlock(); |
b3b304a2 MS |
682 | |
683 | return 0; | |
684 | } | |
685 | EXPORT_SYMBOL(generic_show_options); | |
686 | ||
687 | /* | |
688 | * If filesystem uses generic_show_options(), this function should be | |
689 | * called from the fill_super() callback. | |
690 | * | |
691 | * The .remount_fs callback usually needs to be handled in a special | |
692 | * way, to make sure, that previous options are not overwritten if the | |
693 | * remount fails. | |
694 | * | |
695 | * Also note, that if the filesystem's .remount_fs function doesn't | |
696 | * reset all options to their default value, but changes only newly | |
697 | * given options, then the displayed options will not reflect reality | |
698 | * any more. | |
699 | */ | |
700 | void save_mount_options(struct super_block *sb, char *options) | |
701 | { | |
2a32cebd AV |
702 | BUG_ON(sb->s_options); |
703 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
704 | } |
705 | EXPORT_SYMBOL(save_mount_options); | |
706 | ||
2a32cebd AV |
707 | void replace_mount_options(struct super_block *sb, char *options) |
708 | { | |
709 | char *old = sb->s_options; | |
710 | rcu_assign_pointer(sb->s_options, options); | |
711 | if (old) { | |
712 | synchronize_rcu(); | |
713 | kfree(old); | |
714 | } | |
715 | } | |
716 | EXPORT_SYMBOL(replace_mount_options); | |
717 | ||
a1a2c409 | 718 | #ifdef CONFIG_PROC_FS |
1da177e4 LT |
719 | /* iterator */ |
720 | static void *m_start(struct seq_file *m, loff_t *pos) | |
721 | { | |
a1a2c409 | 722 | struct proc_mounts *p = m->private; |
1da177e4 | 723 | |
390c6843 | 724 | down_read(&namespace_sem); |
a1a2c409 | 725 | return seq_list_start(&p->ns->list, *pos); |
1da177e4 LT |
726 | } |
727 | ||
728 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
729 | { | |
a1a2c409 | 730 | struct proc_mounts *p = m->private; |
b0765fb8 | 731 | |
a1a2c409 | 732 | return seq_list_next(v, &p->ns->list, pos); |
1da177e4 LT |
733 | } |
734 | ||
735 | static void m_stop(struct seq_file *m, void *v) | |
736 | { | |
390c6843 | 737 | up_read(&namespace_sem); |
1da177e4 LT |
738 | } |
739 | ||
2d4d4864 RP |
740 | struct proc_fs_info { |
741 | int flag; | |
742 | const char *str; | |
743 | }; | |
744 | ||
2069f457 | 745 | static int show_sb_opts(struct seq_file *m, struct super_block *sb) |
1da177e4 | 746 | { |
2d4d4864 | 747 | static const struct proc_fs_info fs_info[] = { |
1da177e4 LT |
748 | { MS_SYNCHRONOUS, ",sync" }, |
749 | { MS_DIRSYNC, ",dirsync" }, | |
750 | { MS_MANDLOCK, ",mand" }, | |
1da177e4 LT |
751 | { 0, NULL } |
752 | }; | |
2d4d4864 RP |
753 | const struct proc_fs_info *fs_infop; |
754 | ||
755 | for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { | |
756 | if (sb->s_flags & fs_infop->flag) | |
757 | seq_puts(m, fs_infop->str); | |
758 | } | |
2069f457 EP |
759 | |
760 | return security_sb_show_options(m, sb); | |
2d4d4864 RP |
761 | } |
762 | ||
763 | static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) | |
764 | { | |
765 | static const struct proc_fs_info mnt_info[] = { | |
1da177e4 LT |
766 | { MNT_NOSUID, ",nosuid" }, |
767 | { MNT_NODEV, ",nodev" }, | |
768 | { MNT_NOEXEC, ",noexec" }, | |
fc33a7bb CH |
769 | { MNT_NOATIME, ",noatime" }, |
770 | { MNT_NODIRATIME, ",nodiratime" }, | |
47ae32d6 | 771 | { MNT_RELATIME, ",relatime" }, |
d0adde57 | 772 | { MNT_STRICTATIME, ",strictatime" }, |
1da177e4 LT |
773 | { 0, NULL } |
774 | }; | |
2d4d4864 RP |
775 | const struct proc_fs_info *fs_infop; |
776 | ||
777 | for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { | |
778 | if (mnt->mnt_flags & fs_infop->flag) | |
779 | seq_puts(m, fs_infop->str); | |
780 | } | |
781 | } | |
782 | ||
783 | static void show_type(struct seq_file *m, struct super_block *sb) | |
784 | { | |
785 | mangle(m, sb->s_type->name); | |
786 | if (sb->s_subtype && sb->s_subtype[0]) { | |
787 | seq_putc(m, '.'); | |
788 | mangle(m, sb->s_subtype); | |
789 | } | |
790 | } | |
791 | ||
792 | static int show_vfsmnt(struct seq_file *m, void *v) | |
793 | { | |
794 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
795 | int err = 0; | |
c32c2f63 | 796 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
1da177e4 LT |
797 | |
798 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
799 | seq_putc(m, ' '); | |
c32c2f63 | 800 | seq_path(m, &mnt_path, " \t\n\\"); |
1da177e4 | 801 | seq_putc(m, ' '); |
2d4d4864 | 802 | show_type(m, mnt->mnt_sb); |
2e4b7fcd | 803 | seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); |
2069f457 EP |
804 | err = show_sb_opts(m, mnt->mnt_sb); |
805 | if (err) | |
806 | goto out; | |
2d4d4864 | 807 | show_mnt_opts(m, mnt); |
1da177e4 LT |
808 | if (mnt->mnt_sb->s_op->show_options) |
809 | err = mnt->mnt_sb->s_op->show_options(m, mnt); | |
810 | seq_puts(m, " 0 0\n"); | |
2069f457 | 811 | out: |
1da177e4 LT |
812 | return err; |
813 | } | |
814 | ||
a1a2c409 | 815 | const struct seq_operations mounts_op = { |
1da177e4 LT |
816 | .start = m_start, |
817 | .next = m_next, | |
818 | .stop = m_stop, | |
819 | .show = show_vfsmnt | |
820 | }; | |
821 | ||
2d4d4864 RP |
822 | static int show_mountinfo(struct seq_file *m, void *v) |
823 | { | |
824 | struct proc_mounts *p = m->private; | |
825 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); | |
826 | struct super_block *sb = mnt->mnt_sb; | |
827 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; | |
828 | struct path root = p->root; | |
829 | int err = 0; | |
830 | ||
831 | seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, | |
832 | MAJOR(sb->s_dev), MINOR(sb->s_dev)); | |
833 | seq_dentry(m, mnt->mnt_root, " \t\n\\"); | |
834 | seq_putc(m, ' '); | |
835 | seq_path_root(m, &mnt_path, &root, " \t\n\\"); | |
836 | if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { | |
837 | /* | |
838 | * Mountpoint is outside root, discard that one. Ugly, | |
839 | * but less so than trying to do that in iterator in a | |
840 | * race-free way (due to renames). | |
841 | */ | |
842 | return SEQ_SKIP; | |
843 | } | |
844 | seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); | |
845 | show_mnt_opts(m, mnt); | |
846 | ||
847 | /* Tagged fields ("foo:X" or "bar") */ | |
848 | if (IS_MNT_SHARED(mnt)) | |
849 | seq_printf(m, " shared:%i", mnt->mnt_group_id); | |
97e7e0f7 MS |
850 | if (IS_MNT_SLAVE(mnt)) { |
851 | int master = mnt->mnt_master->mnt_group_id; | |
852 | int dom = get_dominating_id(mnt, &p->root); | |
853 | seq_printf(m, " master:%i", master); | |
854 | if (dom && dom != master) | |
855 | seq_printf(m, " propagate_from:%i", dom); | |
856 | } | |
2d4d4864 RP |
857 | if (IS_MNT_UNBINDABLE(mnt)) |
858 | seq_puts(m, " unbindable"); | |
859 | ||
860 | /* Filesystem specific data */ | |
861 | seq_puts(m, " - "); | |
862 | show_type(m, sb); | |
863 | seq_putc(m, ' '); | |
864 | mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); | |
865 | seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); | |
2069f457 EP |
866 | err = show_sb_opts(m, sb); |
867 | if (err) | |
868 | goto out; | |
2d4d4864 RP |
869 | if (sb->s_op->show_options) |
870 | err = sb->s_op->show_options(m, mnt); | |
871 | seq_putc(m, '\n'); | |
2069f457 | 872 | out: |
2d4d4864 RP |
873 | return err; |
874 | } | |
875 | ||
876 | const struct seq_operations mountinfo_op = { | |
877 | .start = m_start, | |
878 | .next = m_next, | |
879 | .stop = m_stop, | |
880 | .show = show_mountinfo, | |
881 | }; | |
882 | ||
b4629fe2 CL |
883 | static int show_vfsstat(struct seq_file *m, void *v) |
884 | { | |
b0765fb8 | 885 | struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); |
c32c2f63 | 886 | struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; |
b4629fe2 CL |
887 | int err = 0; |
888 | ||
889 | /* device */ | |
890 | if (mnt->mnt_devname) { | |
891 | seq_puts(m, "device "); | |
892 | mangle(m, mnt->mnt_devname); | |
893 | } else | |
894 | seq_puts(m, "no device"); | |
895 | ||
896 | /* mount point */ | |
897 | seq_puts(m, " mounted on "); | |
c32c2f63 | 898 | seq_path(m, &mnt_path, " \t\n\\"); |
b4629fe2 CL |
899 | seq_putc(m, ' '); |
900 | ||
901 | /* file system type */ | |
902 | seq_puts(m, "with fstype "); | |
2d4d4864 | 903 | show_type(m, mnt->mnt_sb); |
b4629fe2 CL |
904 | |
905 | /* optional statistics */ | |
906 | if (mnt->mnt_sb->s_op->show_stats) { | |
907 | seq_putc(m, ' '); | |
908 | err = mnt->mnt_sb->s_op->show_stats(m, mnt); | |
909 | } | |
910 | ||
911 | seq_putc(m, '\n'); | |
912 | return err; | |
913 | } | |
914 | ||
a1a2c409 | 915 | const struct seq_operations mountstats_op = { |
b4629fe2 CL |
916 | .start = m_start, |
917 | .next = m_next, | |
918 | .stop = m_stop, | |
919 | .show = show_vfsstat, | |
920 | }; | |
a1a2c409 | 921 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 922 | |
1da177e4 LT |
923 | /** |
924 | * may_umount_tree - check if a mount tree is busy | |
925 | * @mnt: root of mount tree | |
926 | * | |
927 | * This is called to check if a tree of mounts has any | |
928 | * open files, pwds, chroots or sub mounts that are | |
929 | * busy. | |
930 | */ | |
931 | int may_umount_tree(struct vfsmount *mnt) | |
932 | { | |
36341f64 RP |
933 | int actual_refs = 0; |
934 | int minimum_refs = 0; | |
935 | struct vfsmount *p; | |
1da177e4 LT |
936 | |
937 | spin_lock(&vfsmount_lock); | |
36341f64 | 938 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1da177e4 LT |
939 | actual_refs += atomic_read(&p->mnt_count); |
940 | minimum_refs += 2; | |
1da177e4 LT |
941 | } |
942 | spin_unlock(&vfsmount_lock); | |
943 | ||
944 | if (actual_refs > minimum_refs) | |
e3474a8e | 945 | return 0; |
1da177e4 | 946 | |
e3474a8e | 947 | return 1; |
1da177e4 LT |
948 | } |
949 | ||
950 | EXPORT_SYMBOL(may_umount_tree); | |
951 | ||
952 | /** | |
953 | * may_umount - check if a mount point is busy | |
954 | * @mnt: root of mount | |
955 | * | |
956 | * This is called to check if a mount point has any | |
957 | * open files, pwds, chroots or sub mounts. If the | |
958 | * mount has sub mounts this will return busy | |
959 | * regardless of whether the sub mounts are busy. | |
960 | * | |
961 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
962 | * give false negatives. The main reason why it's here is that we need | |
963 | * a non-destructive way to look for easily umountable filesystems. | |
964 | */ | |
965 | int may_umount(struct vfsmount *mnt) | |
966 | { | |
e3474a8e | 967 | int ret = 1; |
a05964f3 RP |
968 | spin_lock(&vfsmount_lock); |
969 | if (propagate_mount_busy(mnt, 2)) | |
e3474a8e | 970 | ret = 0; |
a05964f3 RP |
971 | spin_unlock(&vfsmount_lock); |
972 | return ret; | |
1da177e4 LT |
973 | } |
974 | ||
975 | EXPORT_SYMBOL(may_umount); | |
976 | ||
b90fa9ae | 977 | void release_mounts(struct list_head *head) |
70fbcdf4 RP |
978 | { |
979 | struct vfsmount *mnt; | |
bf066c7d | 980 | while (!list_empty(head)) { |
b5e61818 | 981 | mnt = list_first_entry(head, struct vfsmount, mnt_hash); |
70fbcdf4 RP |
982 | list_del_init(&mnt->mnt_hash); |
983 | if (mnt->mnt_parent != mnt) { | |
984 | struct dentry *dentry; | |
985 | struct vfsmount *m; | |
986 | spin_lock(&vfsmount_lock); | |
987 | dentry = mnt->mnt_mountpoint; | |
988 | m = mnt->mnt_parent; | |
989 | mnt->mnt_mountpoint = mnt->mnt_root; | |
990 | mnt->mnt_parent = mnt; | |
7c4b93d8 | 991 | m->mnt_ghosts--; |
70fbcdf4 RP |
992 | spin_unlock(&vfsmount_lock); |
993 | dput(dentry); | |
994 | mntput(m); | |
995 | } | |
996 | mntput(mnt); | |
997 | } | |
998 | } | |
999 | ||
a05964f3 | 1000 | void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) |
1da177e4 LT |
1001 | { |
1002 | struct vfsmount *p; | |
1da177e4 | 1003 | |
1bfba4e8 AM |
1004 | for (p = mnt; p; p = next_mnt(p, mnt)) |
1005 | list_move(&p->mnt_hash, kill); | |
1da177e4 | 1006 | |
a05964f3 RP |
1007 | if (propagate) |
1008 | propagate_umount(kill); | |
1009 | ||
70fbcdf4 RP |
1010 | list_for_each_entry(p, kill, mnt_hash) { |
1011 | list_del_init(&p->mnt_expire); | |
1012 | list_del_init(&p->mnt_list); | |
6b3286ed KK |
1013 | __touch_mnt_namespace(p->mnt_ns); |
1014 | p->mnt_ns = NULL; | |
70fbcdf4 | 1015 | list_del_init(&p->mnt_child); |
7c4b93d8 AV |
1016 | if (p->mnt_parent != p) { |
1017 | p->mnt_parent->mnt_ghosts++; | |
f30ac319 | 1018 | p->mnt_mountpoint->d_mounted--; |
7c4b93d8 | 1019 | } |
a05964f3 | 1020 | change_mnt_propagation(p, MS_PRIVATE); |
1da177e4 LT |
1021 | } |
1022 | } | |
1023 | ||
c35038be AV |
1024 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); |
1025 | ||
1da177e4 LT |
1026 | static int do_umount(struct vfsmount *mnt, int flags) |
1027 | { | |
b58fed8b | 1028 | struct super_block *sb = mnt->mnt_sb; |
1da177e4 | 1029 | int retval; |
70fbcdf4 | 1030 | LIST_HEAD(umount_list); |
1da177e4 LT |
1031 | |
1032 | retval = security_sb_umount(mnt, flags); | |
1033 | if (retval) | |
1034 | return retval; | |
1035 | ||
1036 | /* | |
1037 | * Allow userspace to request a mountpoint be expired rather than | |
1038 | * unmounting unconditionally. Unmount only happens if: | |
1039 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1040 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1041 | */ | |
1042 | if (flags & MNT_EXPIRE) { | |
6ac08c39 | 1043 | if (mnt == current->fs->root.mnt || |
1da177e4 LT |
1044 | flags & (MNT_FORCE | MNT_DETACH)) |
1045 | return -EINVAL; | |
1046 | ||
1047 | if (atomic_read(&mnt->mnt_count) != 2) | |
1048 | return -EBUSY; | |
1049 | ||
1050 | if (!xchg(&mnt->mnt_expiry_mark, 1)) | |
1051 | return -EAGAIN; | |
1052 | } | |
1053 | ||
1054 | /* | |
1055 | * If we may have to abort operations to get out of this | |
1056 | * mount, and they will themselves hold resources we must | |
1057 | * allow the fs to do things. In the Unix tradition of | |
1058 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1059 | * might fail to complete on the first run through as other tasks | |
1060 | * must return, and the like. Thats for the mount program to worry | |
1061 | * about for the moment. | |
1062 | */ | |
1063 | ||
42faad99 | 1064 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1065 | sb->s_op->umount_begin(sb); |
42faad99 | 1066 | } |
1da177e4 LT |
1067 | |
1068 | /* | |
1069 | * No sense to grab the lock for this test, but test itself looks | |
1070 | * somewhat bogus. Suggestions for better replacement? | |
1071 | * Ho-hum... In principle, we might treat that as umount + switch | |
1072 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1073 | * Actually it makes sense, especially if rootfs would contain a | |
1074 | * /reboot - static binary that would close all descriptors and | |
1075 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1076 | */ | |
6ac08c39 | 1077 | if (mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1078 | /* |
1079 | * Special case for "unmounting" root ... | |
1080 | * we just try to remount it readonly. | |
1081 | */ | |
1082 | down_write(&sb->s_umount); | |
4aa98cf7 | 1083 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1084 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1085 | up_write(&sb->s_umount); |
1086 | return retval; | |
1087 | } | |
1088 | ||
390c6843 | 1089 | down_write(&namespace_sem); |
1da177e4 | 1090 | spin_lock(&vfsmount_lock); |
5addc5dd | 1091 | event++; |
1da177e4 | 1092 | |
c35038be AV |
1093 | if (!(flags & MNT_DETACH)) |
1094 | shrink_submounts(mnt, &umount_list); | |
1095 | ||
1da177e4 | 1096 | retval = -EBUSY; |
a05964f3 | 1097 | if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { |
1da177e4 | 1098 | if (!list_empty(&mnt->mnt_list)) |
a05964f3 | 1099 | umount_tree(mnt, 1, &umount_list); |
1da177e4 LT |
1100 | retval = 0; |
1101 | } | |
1102 | spin_unlock(&vfsmount_lock); | |
1103 | if (retval) | |
1104 | security_sb_umount_busy(mnt); | |
390c6843 | 1105 | up_write(&namespace_sem); |
70fbcdf4 | 1106 | release_mounts(&umount_list); |
1da177e4 LT |
1107 | return retval; |
1108 | } | |
1109 | ||
1110 | /* | |
1111 | * Now umount can handle mount points as well as block devices. | |
1112 | * This is important for filesystems which use unnamed block devices. | |
1113 | * | |
1114 | * We now support a flag for forced unmount like the other 'big iron' | |
1115 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1116 | */ | |
1117 | ||
bdc480e3 | 1118 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1119 | { |
2d8f3038 | 1120 | struct path path; |
1da177e4 LT |
1121 | int retval; |
1122 | ||
2d8f3038 | 1123 | retval = user_path(name, &path); |
1da177e4 LT |
1124 | if (retval) |
1125 | goto out; | |
1126 | retval = -EINVAL; | |
2d8f3038 | 1127 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1128 | goto dput_and_out; |
2d8f3038 | 1129 | if (!check_mnt(path.mnt)) |
1da177e4 LT |
1130 | goto dput_and_out; |
1131 | ||
1132 | retval = -EPERM; | |
1133 | if (!capable(CAP_SYS_ADMIN)) | |
1134 | goto dput_and_out; | |
1135 | ||
2d8f3038 | 1136 | retval = do_umount(path.mnt, flags); |
1da177e4 | 1137 | dput_and_out: |
429731b1 | 1138 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 AV |
1139 | dput(path.dentry); |
1140 | mntput_no_expire(path.mnt); | |
1da177e4 LT |
1141 | out: |
1142 | return retval; | |
1143 | } | |
1144 | ||
1145 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1146 | ||
1147 | /* | |
b58fed8b | 1148 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1149 | */ |
bdc480e3 | 1150 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1151 | { |
b58fed8b | 1152 | return sys_umount(name, 0); |
1da177e4 LT |
1153 | } |
1154 | ||
1155 | #endif | |
1156 | ||
2d92ab3c | 1157 | static int mount_is_safe(struct path *path) |
1da177e4 LT |
1158 | { |
1159 | if (capable(CAP_SYS_ADMIN)) | |
1160 | return 0; | |
1161 | return -EPERM; | |
1162 | #ifdef notyet | |
2d92ab3c | 1163 | if (S_ISLNK(path->dentry->d_inode->i_mode)) |
1da177e4 | 1164 | return -EPERM; |
2d92ab3c | 1165 | if (path->dentry->d_inode->i_mode & S_ISVTX) { |
da9592ed | 1166 | if (current_uid() != path->dentry->d_inode->i_uid) |
1da177e4 LT |
1167 | return -EPERM; |
1168 | } | |
2d92ab3c | 1169 | if (inode_permission(path->dentry->d_inode, MAY_WRITE)) |
1da177e4 LT |
1170 | return -EPERM; |
1171 | return 0; | |
1172 | #endif | |
1173 | } | |
1174 | ||
b90fa9ae | 1175 | struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, |
36341f64 | 1176 | int flag) |
1da177e4 LT |
1177 | { |
1178 | struct vfsmount *res, *p, *q, *r, *s; | |
1a390689 | 1179 | struct path path; |
1da177e4 | 1180 | |
9676f0c6 RP |
1181 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) |
1182 | return NULL; | |
1183 | ||
36341f64 | 1184 | res = q = clone_mnt(mnt, dentry, flag); |
1da177e4 LT |
1185 | if (!q) |
1186 | goto Enomem; | |
1187 | q->mnt_mountpoint = mnt->mnt_mountpoint; | |
1188 | ||
1189 | p = mnt; | |
fdadd65f | 1190 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
7ec02ef1 | 1191 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1192 | continue; |
1193 | ||
1194 | for (s = r; s; s = next_mnt(s, r)) { | |
9676f0c6 RP |
1195 | if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) { |
1196 | s = skip_mnt_tree(s); | |
1197 | continue; | |
1198 | } | |
1da177e4 LT |
1199 | while (p != s->mnt_parent) { |
1200 | p = p->mnt_parent; | |
1201 | q = q->mnt_parent; | |
1202 | } | |
1203 | p = s; | |
1a390689 AV |
1204 | path.mnt = q; |
1205 | path.dentry = p->mnt_mountpoint; | |
36341f64 | 1206 | q = clone_mnt(p, p->mnt_root, flag); |
1da177e4 LT |
1207 | if (!q) |
1208 | goto Enomem; | |
1209 | spin_lock(&vfsmount_lock); | |
1210 | list_add_tail(&q->mnt_list, &res->mnt_list); | |
1a390689 | 1211 | attach_mnt(q, &path); |
1da177e4 LT |
1212 | spin_unlock(&vfsmount_lock); |
1213 | } | |
1214 | } | |
1215 | return res; | |
b58fed8b | 1216 | Enomem: |
1da177e4 | 1217 | if (res) { |
70fbcdf4 | 1218 | LIST_HEAD(umount_list); |
1da177e4 | 1219 | spin_lock(&vfsmount_lock); |
a05964f3 | 1220 | umount_tree(res, 0, &umount_list); |
1da177e4 | 1221 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 1222 | release_mounts(&umount_list); |
1da177e4 LT |
1223 | } |
1224 | return NULL; | |
1225 | } | |
1226 | ||
589ff870 | 1227 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 AV |
1228 | { |
1229 | struct vfsmount *tree; | |
1a60a280 | 1230 | down_write(&namespace_sem); |
589ff870 | 1231 | tree = copy_tree(path->mnt, path->dentry, CL_COPY_ALL | CL_PRIVATE); |
1a60a280 | 1232 | up_write(&namespace_sem); |
8aec0809 AV |
1233 | return tree; |
1234 | } | |
1235 | ||
1236 | void drop_collected_mounts(struct vfsmount *mnt) | |
1237 | { | |
1238 | LIST_HEAD(umount_list); | |
1a60a280 | 1239 | down_write(&namespace_sem); |
8aec0809 AV |
1240 | spin_lock(&vfsmount_lock); |
1241 | umount_tree(mnt, 0, &umount_list); | |
1242 | spin_unlock(&vfsmount_lock); | |
1a60a280 | 1243 | up_write(&namespace_sem); |
8aec0809 AV |
1244 | release_mounts(&umount_list); |
1245 | } | |
1246 | ||
719f5d7f MS |
1247 | static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) |
1248 | { | |
1249 | struct vfsmount *p; | |
1250 | ||
1251 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { | |
1252 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) | |
1253 | mnt_release_group_id(p); | |
1254 | } | |
1255 | } | |
1256 | ||
1257 | static int invent_group_ids(struct vfsmount *mnt, bool recurse) | |
1258 | { | |
1259 | struct vfsmount *p; | |
1260 | ||
1261 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { | |
1262 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { | |
1263 | int err = mnt_alloc_group_id(p); | |
1264 | if (err) { | |
1265 | cleanup_group_ids(mnt, p); | |
1266 | return err; | |
1267 | } | |
1268 | } | |
1269 | } | |
1270 | ||
1271 | return 0; | |
1272 | } | |
1273 | ||
b90fa9ae RP |
1274 | /* |
1275 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1276 | * @nd : place the mount tree @source_mnt is attached |
1277 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1278 | * store the parent mount and mountpoint dentry. | |
1279 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1280 | * |
1281 | * NOTE: in the table below explains the semantics when a source mount | |
1282 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1283 | * --------------------------------------------------------------------------- |
1284 | * | BIND MOUNT OPERATION | | |
1285 | * |************************************************************************** | |
1286 | * | source-->| shared | private | slave | unbindable | | |
1287 | * | dest | | | | | | |
1288 | * | | | | | | | | |
1289 | * | v | | | | | | |
1290 | * |************************************************************************** | |
1291 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1292 | * | | | | | | | |
1293 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1294 | * *************************************************************************** | |
b90fa9ae RP |
1295 | * A bind operation clones the source mount and mounts the clone on the |
1296 | * destination mount. | |
1297 | * | |
1298 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1299 | * tree of the destination mount and the cloned mount is added to | |
1300 | * the peer group of the source mount. | |
1301 | * (+) the cloned mount is created under the destination mount and is marked | |
1302 | * as shared. The cloned mount is added to the peer group of the source | |
1303 | * mount. | |
5afe0022 RP |
1304 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1305 | * of the destination mount and the cloned mount is made slave | |
1306 | * of the same master as that of the source mount. The cloned mount | |
1307 | * is marked as 'shared and slave'. | |
1308 | * (*) the cloned mount is made a slave of the same master as that of the | |
1309 | * source mount. | |
1310 | * | |
9676f0c6 RP |
1311 | * --------------------------------------------------------------------------- |
1312 | * | MOVE MOUNT OPERATION | | |
1313 | * |************************************************************************** | |
1314 | * | source-->| shared | private | slave | unbindable | | |
1315 | * | dest | | | | | | |
1316 | * | | | | | | | | |
1317 | * | v | | | | | | |
1318 | * |************************************************************************** | |
1319 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1320 | * | | | | | | | |
1321 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1322 | * *************************************************************************** | |
5afe0022 RP |
1323 | * |
1324 | * (+) the mount is moved to the destination. And is then propagated to | |
1325 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1326 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1327 | * (+++) the mount is moved to the destination and is then propagated to |
1328 | * all the mounts belonging to the destination mount's propagation tree. | |
1329 | * the mount is marked as 'shared and slave'. | |
1330 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1331 | * |
1332 | * if the source mount is a tree, the operations explained above is | |
1333 | * applied to each mount in the tree. | |
1334 | * Must be called without spinlocks held, since this function can sleep | |
1335 | * in allocations. | |
1336 | */ | |
1337 | static int attach_recursive_mnt(struct vfsmount *source_mnt, | |
1a390689 | 1338 | struct path *path, struct path *parent_path) |
b90fa9ae RP |
1339 | { |
1340 | LIST_HEAD(tree_list); | |
1a390689 AV |
1341 | struct vfsmount *dest_mnt = path->mnt; |
1342 | struct dentry *dest_dentry = path->dentry; | |
b90fa9ae | 1343 | struct vfsmount *child, *p; |
719f5d7f | 1344 | int err; |
b90fa9ae | 1345 | |
719f5d7f MS |
1346 | if (IS_MNT_SHARED(dest_mnt)) { |
1347 | err = invent_group_ids(source_mnt, true); | |
1348 | if (err) | |
1349 | goto out; | |
1350 | } | |
1351 | err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); | |
1352 | if (err) | |
1353 | goto out_cleanup_ids; | |
b90fa9ae RP |
1354 | |
1355 | if (IS_MNT_SHARED(dest_mnt)) { | |
1356 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) | |
1357 | set_mnt_shared(p); | |
1358 | } | |
1359 | ||
1360 | spin_lock(&vfsmount_lock); | |
1a390689 AV |
1361 | if (parent_path) { |
1362 | detach_mnt(source_mnt, parent_path); | |
1363 | attach_mnt(source_mnt, path); | |
e5d67f07 | 1364 | touch_mnt_namespace(parent_path->mnt->mnt_ns); |
21444403 RP |
1365 | } else { |
1366 | mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); | |
1367 | commit_tree(source_mnt); | |
1368 | } | |
b90fa9ae RP |
1369 | |
1370 | list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { | |
1371 | list_del_init(&child->mnt_hash); | |
1372 | commit_tree(child); | |
1373 | } | |
1374 | spin_unlock(&vfsmount_lock); | |
1375 | return 0; | |
719f5d7f MS |
1376 | |
1377 | out_cleanup_ids: | |
1378 | if (IS_MNT_SHARED(dest_mnt)) | |
1379 | cleanup_group_ids(source_mnt, NULL); | |
1380 | out: | |
1381 | return err; | |
b90fa9ae RP |
1382 | } |
1383 | ||
8c3ee42e | 1384 | static int graft_tree(struct vfsmount *mnt, struct path *path) |
1da177e4 LT |
1385 | { |
1386 | int err; | |
1387 | if (mnt->mnt_sb->s_flags & MS_NOUSER) | |
1388 | return -EINVAL; | |
1389 | ||
8c3ee42e | 1390 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1da177e4 LT |
1391 | S_ISDIR(mnt->mnt_root->d_inode->i_mode)) |
1392 | return -ENOTDIR; | |
1393 | ||
1394 | err = -ENOENT; | |
8c3ee42e AV |
1395 | mutex_lock(&path->dentry->d_inode->i_mutex); |
1396 | if (IS_DEADDIR(path->dentry->d_inode)) | |
1da177e4 LT |
1397 | goto out_unlock; |
1398 | ||
8c3ee42e | 1399 | err = security_sb_check_sb(mnt, path); |
1da177e4 LT |
1400 | if (err) |
1401 | goto out_unlock; | |
1402 | ||
1403 | err = -ENOENT; | |
f3da392e | 1404 | if (!d_unlinked(path->dentry)) |
8c3ee42e | 1405 | err = attach_recursive_mnt(mnt, path, NULL); |
1da177e4 | 1406 | out_unlock: |
8c3ee42e | 1407 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 | 1408 | if (!err) |
8c3ee42e | 1409 | security_sb_post_addmount(mnt, path); |
1da177e4 LT |
1410 | return err; |
1411 | } | |
1412 | ||
07b20889 RP |
1413 | /* |
1414 | * recursively change the type of the mountpoint. | |
1415 | */ | |
0a0d8a46 | 1416 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1417 | { |
2d92ab3c | 1418 | struct vfsmount *m, *mnt = path->mnt; |
07b20889 RP |
1419 | int recurse = flag & MS_REC; |
1420 | int type = flag & ~MS_REC; | |
719f5d7f | 1421 | int err = 0; |
07b20889 | 1422 | |
ee6f9582 MS |
1423 | if (!capable(CAP_SYS_ADMIN)) |
1424 | return -EPERM; | |
1425 | ||
2d92ab3c | 1426 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
1427 | return -EINVAL; |
1428 | ||
1429 | down_write(&namespace_sem); | |
719f5d7f MS |
1430 | if (type == MS_SHARED) { |
1431 | err = invent_group_ids(mnt, recurse); | |
1432 | if (err) | |
1433 | goto out_unlock; | |
1434 | } | |
1435 | ||
07b20889 RP |
1436 | spin_lock(&vfsmount_lock); |
1437 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) | |
1438 | change_mnt_propagation(m, type); | |
1439 | spin_unlock(&vfsmount_lock); | |
719f5d7f MS |
1440 | |
1441 | out_unlock: | |
07b20889 | 1442 | up_write(&namespace_sem); |
719f5d7f | 1443 | return err; |
07b20889 RP |
1444 | } |
1445 | ||
1da177e4 LT |
1446 | /* |
1447 | * do loopback mount. | |
1448 | */ | |
0a0d8a46 | 1449 | static int do_loopback(struct path *path, char *old_name, |
2dafe1c4 | 1450 | int recurse) |
1da177e4 | 1451 | { |
2d92ab3c | 1452 | struct path old_path; |
1da177e4 | 1453 | struct vfsmount *mnt = NULL; |
2d92ab3c | 1454 | int err = mount_is_safe(path); |
1da177e4 LT |
1455 | if (err) |
1456 | return err; | |
1457 | if (!old_name || !*old_name) | |
1458 | return -EINVAL; | |
2d92ab3c | 1459 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1460 | if (err) |
1461 | return err; | |
1462 | ||
390c6843 | 1463 | down_write(&namespace_sem); |
1da177e4 | 1464 | err = -EINVAL; |
2d92ab3c | 1465 | if (IS_MNT_UNBINDABLE(old_path.mnt)) |
4ac91378 | 1466 | goto out; |
9676f0c6 | 1467 | |
2d92ab3c | 1468 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
ccd48bc7 | 1469 | goto out; |
1da177e4 | 1470 | |
ccd48bc7 AV |
1471 | err = -ENOMEM; |
1472 | if (recurse) | |
2d92ab3c | 1473 | mnt = copy_tree(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 | 1474 | else |
2d92ab3c | 1475 | mnt = clone_mnt(old_path.mnt, old_path.dentry, 0); |
ccd48bc7 AV |
1476 | |
1477 | if (!mnt) | |
1478 | goto out; | |
1479 | ||
2d92ab3c | 1480 | err = graft_tree(mnt, path); |
ccd48bc7 | 1481 | if (err) { |
70fbcdf4 | 1482 | LIST_HEAD(umount_list); |
1da177e4 | 1483 | spin_lock(&vfsmount_lock); |
a05964f3 | 1484 | umount_tree(mnt, 0, &umount_list); |
1da177e4 | 1485 | spin_unlock(&vfsmount_lock); |
70fbcdf4 | 1486 | release_mounts(&umount_list); |
5b83d2c5 | 1487 | } |
1da177e4 | 1488 | |
ccd48bc7 | 1489 | out: |
390c6843 | 1490 | up_write(&namespace_sem); |
2d92ab3c | 1491 | path_put(&old_path); |
1da177e4 LT |
1492 | return err; |
1493 | } | |
1494 | ||
2e4b7fcd DH |
1495 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
1496 | { | |
1497 | int error = 0; | |
1498 | int readonly_request = 0; | |
1499 | ||
1500 | if (ms_flags & MS_RDONLY) | |
1501 | readonly_request = 1; | |
1502 | if (readonly_request == __mnt_is_readonly(mnt)) | |
1503 | return 0; | |
1504 | ||
1505 | if (readonly_request) | |
1506 | error = mnt_make_readonly(mnt); | |
1507 | else | |
1508 | __mnt_unmake_readonly(mnt); | |
1509 | return error; | |
1510 | } | |
1511 | ||
1da177e4 LT |
1512 | /* |
1513 | * change filesystem flags. dir should be a physical root of filesystem. | |
1514 | * If you've mounted a non-root directory somewhere and want to do remount | |
1515 | * on it - tough luck. | |
1516 | */ | |
0a0d8a46 | 1517 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
1518 | void *data) |
1519 | { | |
1520 | int err; | |
2d92ab3c | 1521 | struct super_block *sb = path->mnt->mnt_sb; |
1da177e4 LT |
1522 | |
1523 | if (!capable(CAP_SYS_ADMIN)) | |
1524 | return -EPERM; | |
1525 | ||
2d92ab3c | 1526 | if (!check_mnt(path->mnt)) |
1da177e4 LT |
1527 | return -EINVAL; |
1528 | ||
2d92ab3c | 1529 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
1530 | return -EINVAL; |
1531 | ||
1532 | down_write(&sb->s_umount); | |
2e4b7fcd | 1533 | if (flags & MS_BIND) |
2d92ab3c | 1534 | err = change_mount_flags(path->mnt, flags); |
4aa98cf7 | 1535 | else |
2e4b7fcd | 1536 | err = do_remount_sb(sb, flags, data, 0); |
1da177e4 | 1537 | if (!err) |
2d92ab3c | 1538 | path->mnt->mnt_flags = mnt_flags; |
1da177e4 | 1539 | up_write(&sb->s_umount); |
0e55a7cc | 1540 | if (!err) { |
2d92ab3c | 1541 | security_sb_post_remount(path->mnt, flags, data); |
0e55a7cc DW |
1542 | |
1543 | spin_lock(&vfsmount_lock); | |
1544 | touch_mnt_namespace(path->mnt->mnt_ns); | |
1545 | spin_unlock(&vfsmount_lock); | |
1546 | } | |
1da177e4 LT |
1547 | return err; |
1548 | } | |
1549 | ||
9676f0c6 RP |
1550 | static inline int tree_contains_unbindable(struct vfsmount *mnt) |
1551 | { | |
1552 | struct vfsmount *p; | |
1553 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
1554 | if (IS_MNT_UNBINDABLE(p)) | |
1555 | return 1; | |
1556 | } | |
1557 | return 0; | |
1558 | } | |
1559 | ||
0a0d8a46 | 1560 | static int do_move_mount(struct path *path, char *old_name) |
1da177e4 | 1561 | { |
2d92ab3c | 1562 | struct path old_path, parent_path; |
1da177e4 LT |
1563 | struct vfsmount *p; |
1564 | int err = 0; | |
1565 | if (!capable(CAP_SYS_ADMIN)) | |
1566 | return -EPERM; | |
1567 | if (!old_name || !*old_name) | |
1568 | return -EINVAL; | |
2d92ab3c | 1569 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1570 | if (err) |
1571 | return err; | |
1572 | ||
390c6843 | 1573 | down_write(&namespace_sem); |
2d92ab3c | 1574 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1575 | follow_down(path)) |
1da177e4 LT |
1576 | ; |
1577 | err = -EINVAL; | |
2d92ab3c | 1578 | if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt)) |
1da177e4 LT |
1579 | goto out; |
1580 | ||
1581 | err = -ENOENT; | |
2d92ab3c AV |
1582 | mutex_lock(&path->dentry->d_inode->i_mutex); |
1583 | if (IS_DEADDIR(path->dentry->d_inode)) | |
1da177e4 LT |
1584 | goto out1; |
1585 | ||
f3da392e | 1586 | if (d_unlinked(path->dentry)) |
21444403 | 1587 | goto out1; |
1da177e4 LT |
1588 | |
1589 | err = -EINVAL; | |
2d92ab3c | 1590 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 1591 | goto out1; |
1da177e4 | 1592 | |
2d92ab3c | 1593 | if (old_path.mnt == old_path.mnt->mnt_parent) |
21444403 | 1594 | goto out1; |
1da177e4 | 1595 | |
2d92ab3c AV |
1596 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
1597 | S_ISDIR(old_path.dentry->d_inode->i_mode)) | |
21444403 RP |
1598 | goto out1; |
1599 | /* | |
1600 | * Don't move a mount residing in a shared parent. | |
1601 | */ | |
2d92ab3c AV |
1602 | if (old_path.mnt->mnt_parent && |
1603 | IS_MNT_SHARED(old_path.mnt->mnt_parent)) | |
21444403 | 1604 | goto out1; |
9676f0c6 RP |
1605 | /* |
1606 | * Don't move a mount tree containing unbindable mounts to a destination | |
1607 | * mount which is shared. | |
1608 | */ | |
2d92ab3c AV |
1609 | if (IS_MNT_SHARED(path->mnt) && |
1610 | tree_contains_unbindable(old_path.mnt)) | |
9676f0c6 | 1611 | goto out1; |
1da177e4 | 1612 | err = -ELOOP; |
2d92ab3c AV |
1613 | for (p = path->mnt; p->mnt_parent != p; p = p->mnt_parent) |
1614 | if (p == old_path.mnt) | |
21444403 | 1615 | goto out1; |
1da177e4 | 1616 | |
2d92ab3c | 1617 | err = attach_recursive_mnt(old_path.mnt, path, &parent_path); |
4ac91378 | 1618 | if (err) |
21444403 | 1619 | goto out1; |
1da177e4 LT |
1620 | |
1621 | /* if the mount is moved, it should no longer be expire | |
1622 | * automatically */ | |
2d92ab3c | 1623 | list_del_init(&old_path.mnt->mnt_expire); |
1da177e4 | 1624 | out1: |
2d92ab3c | 1625 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1da177e4 | 1626 | out: |
390c6843 | 1627 | up_write(&namespace_sem); |
1da177e4 | 1628 | if (!err) |
1a390689 | 1629 | path_put(&parent_path); |
2d92ab3c | 1630 | path_put(&old_path); |
1da177e4 LT |
1631 | return err; |
1632 | } | |
1633 | ||
1634 | /* | |
1635 | * create a new mount for userspace and request it to be added into the | |
1636 | * namespace's tree | |
1637 | */ | |
0a0d8a46 | 1638 | static int do_new_mount(struct path *path, char *type, int flags, |
1da177e4 LT |
1639 | int mnt_flags, char *name, void *data) |
1640 | { | |
1641 | struct vfsmount *mnt; | |
1642 | ||
eca6f534 | 1643 | if (!type) |
1da177e4 LT |
1644 | return -EINVAL; |
1645 | ||
1646 | /* we need capabilities... */ | |
1647 | if (!capable(CAP_SYS_ADMIN)) | |
1648 | return -EPERM; | |
1649 | ||
7f78d4cd | 1650 | lock_kernel(); |
1da177e4 | 1651 | mnt = do_kern_mount(type, flags, name, data); |
7f78d4cd | 1652 | unlock_kernel(); |
1da177e4 LT |
1653 | if (IS_ERR(mnt)) |
1654 | return PTR_ERR(mnt); | |
1655 | ||
2d92ab3c | 1656 | return do_add_mount(mnt, path, mnt_flags, NULL); |
1da177e4 LT |
1657 | } |
1658 | ||
1659 | /* | |
1660 | * add a mount into a namespace's mount tree | |
1661 | * - provide the option of adding the new mount to an expiration list | |
1662 | */ | |
8d66bf54 | 1663 | int do_add_mount(struct vfsmount *newmnt, struct path *path, |
1da177e4 LT |
1664 | int mnt_flags, struct list_head *fslist) |
1665 | { | |
1666 | int err; | |
1667 | ||
390c6843 | 1668 | down_write(&namespace_sem); |
1da177e4 | 1669 | /* Something was mounted here while we slept */ |
8d66bf54 | 1670 | while (d_mountpoint(path->dentry) && |
9393bd07 | 1671 | follow_down(path)) |
1da177e4 LT |
1672 | ; |
1673 | err = -EINVAL; | |
dd5cae6e | 1674 | if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt)) |
1da177e4 LT |
1675 | goto unlock; |
1676 | ||
1677 | /* Refuse the same filesystem on the same mount point */ | |
1678 | err = -EBUSY; | |
8d66bf54 AV |
1679 | if (path->mnt->mnt_sb == newmnt->mnt_sb && |
1680 | path->mnt->mnt_root == path->dentry) | |
1da177e4 LT |
1681 | goto unlock; |
1682 | ||
1683 | err = -EINVAL; | |
1684 | if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode)) | |
1685 | goto unlock; | |
1686 | ||
1687 | newmnt->mnt_flags = mnt_flags; | |
8d66bf54 | 1688 | if ((err = graft_tree(newmnt, path))) |
5b83d2c5 | 1689 | goto unlock; |
1da177e4 | 1690 | |
6758f953 | 1691 | if (fslist) /* add to the specified expiration list */ |
55e700b9 | 1692 | list_add_tail(&newmnt->mnt_expire, fslist); |
6758f953 | 1693 | |
390c6843 | 1694 | up_write(&namespace_sem); |
5b83d2c5 | 1695 | return 0; |
1da177e4 LT |
1696 | |
1697 | unlock: | |
390c6843 | 1698 | up_write(&namespace_sem); |
1da177e4 LT |
1699 | mntput(newmnt); |
1700 | return err; | |
1701 | } | |
1702 | ||
1703 | EXPORT_SYMBOL_GPL(do_add_mount); | |
1704 | ||
1705 | /* | |
1706 | * process a list of expirable mountpoints with the intent of discarding any | |
1707 | * mountpoints that aren't in use and haven't been touched since last we came | |
1708 | * here | |
1709 | */ | |
1710 | void mark_mounts_for_expiry(struct list_head *mounts) | |
1711 | { | |
1da177e4 LT |
1712 | struct vfsmount *mnt, *next; |
1713 | LIST_HEAD(graveyard); | |
bcc5c7d2 | 1714 | LIST_HEAD(umounts); |
1da177e4 LT |
1715 | |
1716 | if (list_empty(mounts)) | |
1717 | return; | |
1718 | ||
bcc5c7d2 | 1719 | down_write(&namespace_sem); |
1da177e4 LT |
1720 | spin_lock(&vfsmount_lock); |
1721 | ||
1722 | /* extract from the expiration list every vfsmount that matches the | |
1723 | * following criteria: | |
1724 | * - only referenced by its parent vfsmount | |
1725 | * - still marked for expiry (marked on the last call here; marks are | |
1726 | * cleared by mntput()) | |
1727 | */ | |
55e700b9 | 1728 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
1da177e4 | 1729 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
bcc5c7d2 | 1730 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 1731 | continue; |
55e700b9 | 1732 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 1733 | } |
bcc5c7d2 AV |
1734 | while (!list_empty(&graveyard)) { |
1735 | mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); | |
1736 | touch_mnt_namespace(mnt->mnt_ns); | |
1737 | umount_tree(mnt, 1, &umounts); | |
1738 | } | |
5528f911 | 1739 | spin_unlock(&vfsmount_lock); |
bcc5c7d2 AV |
1740 | up_write(&namespace_sem); |
1741 | ||
1742 | release_mounts(&umounts); | |
5528f911 TM |
1743 | } |
1744 | ||
1745 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
1746 | ||
1747 | /* | |
1748 | * Ripoff of 'select_parent()' | |
1749 | * | |
1750 | * search the list of submounts for a given mountpoint, and move any | |
1751 | * shrinkable submounts to the 'graveyard' list. | |
1752 | */ | |
1753 | static int select_submounts(struct vfsmount *parent, struct list_head *graveyard) | |
1754 | { | |
1755 | struct vfsmount *this_parent = parent; | |
1756 | struct list_head *next; | |
1757 | int found = 0; | |
1758 | ||
1759 | repeat: | |
1760 | next = this_parent->mnt_mounts.next; | |
1761 | resume: | |
1762 | while (next != &this_parent->mnt_mounts) { | |
1763 | struct list_head *tmp = next; | |
1764 | struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child); | |
1765 | ||
1766 | next = tmp->next; | |
1767 | if (!(mnt->mnt_flags & MNT_SHRINKABLE)) | |
1da177e4 | 1768 | continue; |
5528f911 TM |
1769 | /* |
1770 | * Descend a level if the d_mounts list is non-empty. | |
1771 | */ | |
1772 | if (!list_empty(&mnt->mnt_mounts)) { | |
1773 | this_parent = mnt; | |
1774 | goto repeat; | |
1775 | } | |
1da177e4 | 1776 | |
5528f911 | 1777 | if (!propagate_mount_busy(mnt, 1)) { |
5528f911 TM |
1778 | list_move_tail(&mnt->mnt_expire, graveyard); |
1779 | found++; | |
1780 | } | |
1da177e4 | 1781 | } |
5528f911 TM |
1782 | /* |
1783 | * All done at this level ... ascend and resume the search | |
1784 | */ | |
1785 | if (this_parent != parent) { | |
1786 | next = this_parent->mnt_child.next; | |
1787 | this_parent = this_parent->mnt_parent; | |
1788 | goto resume; | |
1789 | } | |
1790 | return found; | |
1791 | } | |
1792 | ||
1793 | /* | |
1794 | * process a list of expirable mountpoints with the intent of discarding any | |
1795 | * submounts of a specific parent mountpoint | |
1796 | */ | |
c35038be | 1797 | static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) |
5528f911 TM |
1798 | { |
1799 | LIST_HEAD(graveyard); | |
c35038be | 1800 | struct vfsmount *m; |
5528f911 | 1801 | |
5528f911 | 1802 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 1803 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 1804 | while (!list_empty(&graveyard)) { |
c35038be | 1805 | m = list_first_entry(&graveyard, struct vfsmount, |
bcc5c7d2 | 1806 | mnt_expire); |
afef80b3 EB |
1807 | touch_mnt_namespace(m->mnt_ns); |
1808 | umount_tree(m, 1, umounts); | |
bcc5c7d2 AV |
1809 | } |
1810 | } | |
1da177e4 LT |
1811 | } |
1812 | ||
1da177e4 LT |
1813 | /* |
1814 | * Some copy_from_user() implementations do not return the exact number of | |
1815 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
1816 | * Note that this function differs from copy_from_user() in that it will oops | |
1817 | * on bad values of `to', rather than returning a short copy. | |
1818 | */ | |
b58fed8b RP |
1819 | static long exact_copy_from_user(void *to, const void __user * from, |
1820 | unsigned long n) | |
1da177e4 LT |
1821 | { |
1822 | char *t = to; | |
1823 | const char __user *f = from; | |
1824 | char c; | |
1825 | ||
1826 | if (!access_ok(VERIFY_READ, from, n)) | |
1827 | return n; | |
1828 | ||
1829 | while (n) { | |
1830 | if (__get_user(c, f)) { | |
1831 | memset(t, 0, n); | |
1832 | break; | |
1833 | } | |
1834 | *t++ = c; | |
1835 | f++; | |
1836 | n--; | |
1837 | } | |
1838 | return n; | |
1839 | } | |
1840 | ||
b58fed8b | 1841 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
1842 | { |
1843 | int i; | |
1844 | unsigned long page; | |
1845 | unsigned long size; | |
b58fed8b | 1846 | |
1da177e4 LT |
1847 | *where = 0; |
1848 | if (!data) | |
1849 | return 0; | |
1850 | ||
1851 | if (!(page = __get_free_page(GFP_KERNEL))) | |
1852 | return -ENOMEM; | |
1853 | ||
1854 | /* We only care that *some* data at the address the user | |
1855 | * gave us is valid. Just in case, we'll zero | |
1856 | * the remainder of the page. | |
1857 | */ | |
1858 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
1859 | size = TASK_SIZE - (unsigned long)data; | |
1860 | if (size > PAGE_SIZE) | |
1861 | size = PAGE_SIZE; | |
1862 | ||
1863 | i = size - exact_copy_from_user((void *)page, data, size); | |
1864 | if (!i) { | |
b58fed8b | 1865 | free_page(page); |
1da177e4 LT |
1866 | return -EFAULT; |
1867 | } | |
1868 | if (i != PAGE_SIZE) | |
1869 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
1870 | *where = page; | |
1871 | return 0; | |
1872 | } | |
1873 | ||
eca6f534 VN |
1874 | int copy_mount_string(const void __user *data, char **where) |
1875 | { | |
1876 | char *tmp; | |
1877 | ||
1878 | if (!data) { | |
1879 | *where = NULL; | |
1880 | return 0; | |
1881 | } | |
1882 | ||
1883 | tmp = strndup_user(data, PAGE_SIZE); | |
1884 | if (IS_ERR(tmp)) | |
1885 | return PTR_ERR(tmp); | |
1886 | ||
1887 | *where = tmp; | |
1888 | return 0; | |
1889 | } | |
1890 | ||
1da177e4 LT |
1891 | /* |
1892 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
1893 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
1894 | * | |
1895 | * data is a (void *) that can point to any structure up to | |
1896 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
1897 | * information (or be NULL). | |
1898 | * | |
1899 | * Pre-0.97 versions of mount() didn't have a flags word. | |
1900 | * When the flags word was introduced its top half was required | |
1901 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
1902 | * Therefore, if this magic number is present, it carries no information | |
1903 | * and must be discarded. | |
1904 | */ | |
b58fed8b | 1905 | long do_mount(char *dev_name, char *dir_name, char *type_page, |
1da177e4 LT |
1906 | unsigned long flags, void *data_page) |
1907 | { | |
2d92ab3c | 1908 | struct path path; |
1da177e4 LT |
1909 | int retval = 0; |
1910 | int mnt_flags = 0; | |
1911 | ||
1912 | /* Discard magic */ | |
1913 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
1914 | flags &= ~MS_MGC_MSK; | |
1915 | ||
1916 | /* Basic sanity checks */ | |
1917 | ||
1918 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
1919 | return -EINVAL; | |
1da177e4 LT |
1920 | |
1921 | if (data_page) | |
1922 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
1923 | ||
a27ab9f2 TH |
1924 | /* ... and get the mountpoint */ |
1925 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); | |
1926 | if (retval) | |
1927 | return retval; | |
1928 | ||
1929 | retval = security_sb_mount(dev_name, &path, | |
1930 | type_page, flags, data_page); | |
1931 | if (retval) | |
1932 | goto dput_out; | |
1933 | ||
613cbe3d AK |
1934 | /* Default to relatime unless overriden */ |
1935 | if (!(flags & MS_NOATIME)) | |
1936 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 1937 | |
1da177e4 LT |
1938 | /* Separate the per-mountpoint flags */ |
1939 | if (flags & MS_NOSUID) | |
1940 | mnt_flags |= MNT_NOSUID; | |
1941 | if (flags & MS_NODEV) | |
1942 | mnt_flags |= MNT_NODEV; | |
1943 | if (flags & MS_NOEXEC) | |
1944 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
1945 | if (flags & MS_NOATIME) |
1946 | mnt_flags |= MNT_NOATIME; | |
1947 | if (flags & MS_NODIRATIME) | |
1948 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
1949 | if (flags & MS_STRICTATIME) |
1950 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
1951 | if (flags & MS_RDONLY) |
1952 | mnt_flags |= MNT_READONLY; | |
fc33a7bb CH |
1953 | |
1954 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | | |
d0adde57 MG |
1955 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
1956 | MS_STRICTATIME); | |
1da177e4 | 1957 | |
1da177e4 | 1958 | if (flags & MS_REMOUNT) |
2d92ab3c | 1959 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
1960 | data_page); |
1961 | else if (flags & MS_BIND) | |
2d92ab3c | 1962 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 1963 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 1964 | retval = do_change_type(&path, flags); |
1da177e4 | 1965 | else if (flags & MS_MOVE) |
2d92ab3c | 1966 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 1967 | else |
2d92ab3c | 1968 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
1969 | dev_name, data_page); |
1970 | dput_out: | |
2d92ab3c | 1971 | path_put(&path); |
1da177e4 LT |
1972 | return retval; |
1973 | } | |
1974 | ||
cf8d2c11 TM |
1975 | static struct mnt_namespace *alloc_mnt_ns(void) |
1976 | { | |
1977 | struct mnt_namespace *new_ns; | |
1978 | ||
1979 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
1980 | if (!new_ns) | |
1981 | return ERR_PTR(-ENOMEM); | |
1982 | atomic_set(&new_ns->count, 1); | |
1983 | new_ns->root = NULL; | |
1984 | INIT_LIST_HEAD(&new_ns->list); | |
1985 | init_waitqueue_head(&new_ns->poll); | |
1986 | new_ns->event = 0; | |
1987 | return new_ns; | |
1988 | } | |
1989 | ||
741a2951 JD |
1990 | /* |
1991 | * Allocate a new namespace structure and populate it with contents | |
1992 | * copied from the namespace of the passed in task structure. | |
1993 | */ | |
e3222c4e | 1994 | static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, |
6b3286ed | 1995 | struct fs_struct *fs) |
1da177e4 | 1996 | { |
6b3286ed | 1997 | struct mnt_namespace *new_ns; |
7f2da1e7 | 1998 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
1da177e4 LT |
1999 | struct vfsmount *p, *q; |
2000 | ||
cf8d2c11 TM |
2001 | new_ns = alloc_mnt_ns(); |
2002 | if (IS_ERR(new_ns)) | |
2003 | return new_ns; | |
1da177e4 | 2004 | |
390c6843 | 2005 | down_write(&namespace_sem); |
1da177e4 | 2006 | /* First pass: copy the tree topology */ |
6b3286ed | 2007 | new_ns->root = copy_tree(mnt_ns->root, mnt_ns->root->mnt_root, |
9676f0c6 | 2008 | CL_COPY_ALL | CL_EXPIRE); |
1da177e4 | 2009 | if (!new_ns->root) { |
390c6843 | 2010 | up_write(&namespace_sem); |
1da177e4 | 2011 | kfree(new_ns); |
5cc4a034 | 2012 | return ERR_PTR(-ENOMEM); |
1da177e4 LT |
2013 | } |
2014 | spin_lock(&vfsmount_lock); | |
2015 | list_add_tail(&new_ns->list, &new_ns->root->mnt_list); | |
2016 | spin_unlock(&vfsmount_lock); | |
2017 | ||
2018 | /* | |
2019 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2020 | * as belonging to new namespace. We have already acquired a private | |
2021 | * fs_struct, so tsk->fs->lock is not needed. | |
2022 | */ | |
6b3286ed | 2023 | p = mnt_ns->root; |
1da177e4 LT |
2024 | q = new_ns->root; |
2025 | while (p) { | |
6b3286ed | 2026 | q->mnt_ns = new_ns; |
1da177e4 | 2027 | if (fs) { |
6ac08c39 | 2028 | if (p == fs->root.mnt) { |
1da177e4 | 2029 | rootmnt = p; |
6ac08c39 | 2030 | fs->root.mnt = mntget(q); |
1da177e4 | 2031 | } |
6ac08c39 | 2032 | if (p == fs->pwd.mnt) { |
1da177e4 | 2033 | pwdmnt = p; |
6ac08c39 | 2034 | fs->pwd.mnt = mntget(q); |
1da177e4 | 2035 | } |
1da177e4 | 2036 | } |
6b3286ed | 2037 | p = next_mnt(p, mnt_ns->root); |
1da177e4 LT |
2038 | q = next_mnt(q, new_ns->root); |
2039 | } | |
390c6843 | 2040 | up_write(&namespace_sem); |
1da177e4 | 2041 | |
1da177e4 LT |
2042 | if (rootmnt) |
2043 | mntput(rootmnt); | |
2044 | if (pwdmnt) | |
2045 | mntput(pwdmnt); | |
1da177e4 | 2046 | |
741a2951 JD |
2047 | return new_ns; |
2048 | } | |
2049 | ||
213dd266 | 2050 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
e3222c4e | 2051 | struct fs_struct *new_fs) |
741a2951 | 2052 | { |
6b3286ed | 2053 | struct mnt_namespace *new_ns; |
741a2951 | 2054 | |
e3222c4e | 2055 | BUG_ON(!ns); |
6b3286ed | 2056 | get_mnt_ns(ns); |
741a2951 JD |
2057 | |
2058 | if (!(flags & CLONE_NEWNS)) | |
e3222c4e | 2059 | return ns; |
741a2951 | 2060 | |
e3222c4e | 2061 | new_ns = dup_mnt_ns(ns, new_fs); |
741a2951 | 2062 | |
6b3286ed | 2063 | put_mnt_ns(ns); |
e3222c4e | 2064 | return new_ns; |
1da177e4 LT |
2065 | } |
2066 | ||
cf8d2c11 TM |
2067 | /** |
2068 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2069 | * @mnt: pointer to the new root filesystem mountpoint | |
2070 | */ | |
a2770d86 | 2071 | struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt) |
cf8d2c11 TM |
2072 | { |
2073 | struct mnt_namespace *new_ns; | |
2074 | ||
2075 | new_ns = alloc_mnt_ns(); | |
2076 | if (!IS_ERR(new_ns)) { | |
2077 | mnt->mnt_ns = new_ns; | |
2078 | new_ns->root = mnt; | |
2079 | list_add(&new_ns->list, &new_ns->root->mnt_list); | |
2080 | } | |
2081 | return new_ns; | |
2082 | } | |
a2770d86 | 2083 | EXPORT_SYMBOL(create_mnt_ns); |
cf8d2c11 | 2084 | |
bdc480e3 HC |
2085 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2086 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2087 | { |
eca6f534 VN |
2088 | int ret; |
2089 | char *kernel_type; | |
2090 | char *kernel_dir; | |
2091 | char *kernel_dev; | |
1da177e4 | 2092 | unsigned long data_page; |
1da177e4 | 2093 | |
eca6f534 VN |
2094 | ret = copy_mount_string(type, &kernel_type); |
2095 | if (ret < 0) | |
2096 | goto out_type; | |
1da177e4 | 2097 | |
eca6f534 VN |
2098 | kernel_dir = getname(dir_name); |
2099 | if (IS_ERR(kernel_dir)) { | |
2100 | ret = PTR_ERR(kernel_dir); | |
2101 | goto out_dir; | |
2102 | } | |
1da177e4 | 2103 | |
eca6f534 VN |
2104 | ret = copy_mount_string(dev_name, &kernel_dev); |
2105 | if (ret < 0) | |
2106 | goto out_dev; | |
1da177e4 | 2107 | |
eca6f534 VN |
2108 | ret = copy_mount_options(data, &data_page); |
2109 | if (ret < 0) | |
2110 | goto out_data; | |
1da177e4 | 2111 | |
eca6f534 VN |
2112 | ret = do_mount(kernel_dev, kernel_dir, kernel_type, flags, |
2113 | (void *) data_page); | |
1da177e4 | 2114 | |
eca6f534 VN |
2115 | free_page(data_page); |
2116 | out_data: | |
2117 | kfree(kernel_dev); | |
2118 | out_dev: | |
2119 | putname(kernel_dir); | |
2120 | out_dir: | |
2121 | kfree(kernel_type); | |
2122 | out_type: | |
2123 | return ret; | |
1da177e4 LT |
2124 | } |
2125 | ||
1da177e4 LT |
2126 | /* |
2127 | * pivot_root Semantics: | |
2128 | * Moves the root file system of the current process to the directory put_old, | |
2129 | * makes new_root as the new root file system of the current process, and sets | |
2130 | * root/cwd of all processes which had them on the current root to new_root. | |
2131 | * | |
2132 | * Restrictions: | |
2133 | * The new_root and put_old must be directories, and must not be on the | |
2134 | * same file system as the current process root. The put_old must be | |
2135 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2136 | * pointed to by put_old must yield the same directory as new_root. No other | |
2137 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2138 | * | |
4a0d11fa NB |
2139 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2140 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2141 | * in this situation. | |
2142 | * | |
1da177e4 LT |
2143 | * Notes: |
2144 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2145 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2146 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2147 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2148 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2149 | * first. | |
2150 | */ | |
3480b257 HC |
2151 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2152 | const char __user *, put_old) | |
1da177e4 LT |
2153 | { |
2154 | struct vfsmount *tmp; | |
2d8f3038 | 2155 | struct path new, old, parent_path, root_parent, root; |
1da177e4 LT |
2156 | int error; |
2157 | ||
2158 | if (!capable(CAP_SYS_ADMIN)) | |
2159 | return -EPERM; | |
2160 | ||
2d8f3038 | 2161 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2162 | if (error) |
2163 | goto out0; | |
2164 | error = -EINVAL; | |
2d8f3038 | 2165 | if (!check_mnt(new.mnt)) |
1da177e4 LT |
2166 | goto out1; |
2167 | ||
2d8f3038 | 2168 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2169 | if (error) |
2170 | goto out1; | |
2171 | ||
2d8f3038 | 2172 | error = security_sb_pivotroot(&old, &new); |
1da177e4 | 2173 | if (error) { |
2d8f3038 | 2174 | path_put(&old); |
1da177e4 LT |
2175 | goto out1; |
2176 | } | |
2177 | ||
2178 | read_lock(¤t->fs->lock); | |
8c3ee42e | 2179 | root = current->fs->root; |
6ac08c39 | 2180 | path_get(¤t->fs->root); |
1da177e4 | 2181 | read_unlock(¤t->fs->lock); |
390c6843 | 2182 | down_write(&namespace_sem); |
2d8f3038 | 2183 | mutex_lock(&old.dentry->d_inode->i_mutex); |
1da177e4 | 2184 | error = -EINVAL; |
2d8f3038 AV |
2185 | if (IS_MNT_SHARED(old.mnt) || |
2186 | IS_MNT_SHARED(new.mnt->mnt_parent) || | |
8c3ee42e | 2187 | IS_MNT_SHARED(root.mnt->mnt_parent)) |
21444403 | 2188 | goto out2; |
8c3ee42e | 2189 | if (!check_mnt(root.mnt)) |
1da177e4 LT |
2190 | goto out2; |
2191 | error = -ENOENT; | |
2d8f3038 | 2192 | if (IS_DEADDIR(new.dentry->d_inode)) |
1da177e4 | 2193 | goto out2; |
f3da392e | 2194 | if (d_unlinked(new.dentry)) |
1da177e4 | 2195 | goto out2; |
f3da392e | 2196 | if (d_unlinked(old.dentry)) |
1da177e4 LT |
2197 | goto out2; |
2198 | error = -EBUSY; | |
2d8f3038 AV |
2199 | if (new.mnt == root.mnt || |
2200 | old.mnt == root.mnt) | |
1da177e4 LT |
2201 | goto out2; /* loop, on the same file system */ |
2202 | error = -EINVAL; | |
8c3ee42e | 2203 | if (root.mnt->mnt_root != root.dentry) |
1da177e4 | 2204 | goto out2; /* not a mountpoint */ |
8c3ee42e | 2205 | if (root.mnt->mnt_parent == root.mnt) |
0bb6fcc1 | 2206 | goto out2; /* not attached */ |
2d8f3038 | 2207 | if (new.mnt->mnt_root != new.dentry) |
1da177e4 | 2208 | goto out2; /* not a mountpoint */ |
2d8f3038 | 2209 | if (new.mnt->mnt_parent == new.mnt) |
0bb6fcc1 | 2210 | goto out2; /* not attached */ |
4ac91378 | 2211 | /* make sure we can reach put_old from new_root */ |
2d8f3038 | 2212 | tmp = old.mnt; |
1da177e4 | 2213 | spin_lock(&vfsmount_lock); |
2d8f3038 | 2214 | if (tmp != new.mnt) { |
1da177e4 LT |
2215 | for (;;) { |
2216 | if (tmp->mnt_parent == tmp) | |
2217 | goto out3; /* already mounted on put_old */ | |
2d8f3038 | 2218 | if (tmp->mnt_parent == new.mnt) |
1da177e4 LT |
2219 | break; |
2220 | tmp = tmp->mnt_parent; | |
2221 | } | |
2d8f3038 | 2222 | if (!is_subdir(tmp->mnt_mountpoint, new.dentry)) |
1da177e4 | 2223 | goto out3; |
2d8f3038 | 2224 | } else if (!is_subdir(old.dentry, new.dentry)) |
1da177e4 | 2225 | goto out3; |
2d8f3038 | 2226 | detach_mnt(new.mnt, &parent_path); |
8c3ee42e | 2227 | detach_mnt(root.mnt, &root_parent); |
4ac91378 | 2228 | /* mount old root on put_old */ |
2d8f3038 | 2229 | attach_mnt(root.mnt, &old); |
4ac91378 | 2230 | /* mount new_root on / */ |
2d8f3038 | 2231 | attach_mnt(new.mnt, &root_parent); |
6b3286ed | 2232 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
1da177e4 | 2233 | spin_unlock(&vfsmount_lock); |
2d8f3038 AV |
2234 | chroot_fs_refs(&root, &new); |
2235 | security_sb_post_pivotroot(&root, &new); | |
1da177e4 | 2236 | error = 0; |
1a390689 AV |
2237 | path_put(&root_parent); |
2238 | path_put(&parent_path); | |
1da177e4 | 2239 | out2: |
2d8f3038 | 2240 | mutex_unlock(&old.dentry->d_inode->i_mutex); |
390c6843 | 2241 | up_write(&namespace_sem); |
8c3ee42e | 2242 | path_put(&root); |
2d8f3038 | 2243 | path_put(&old); |
1da177e4 | 2244 | out1: |
2d8f3038 | 2245 | path_put(&new); |
1da177e4 | 2246 | out0: |
1da177e4 LT |
2247 | return error; |
2248 | out3: | |
2249 | spin_unlock(&vfsmount_lock); | |
2250 | goto out2; | |
2251 | } | |
2252 | ||
2253 | static void __init init_mount_tree(void) | |
2254 | { | |
2255 | struct vfsmount *mnt; | |
6b3286ed | 2256 | struct mnt_namespace *ns; |
ac748a09 | 2257 | struct path root; |
1da177e4 LT |
2258 | |
2259 | mnt = do_kern_mount("rootfs", 0, "rootfs", NULL); | |
2260 | if (IS_ERR(mnt)) | |
2261 | panic("Can't create rootfs"); | |
3b22edc5 TM |
2262 | ns = create_mnt_ns(mnt); |
2263 | if (IS_ERR(ns)) | |
1da177e4 | 2264 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
2265 | |
2266 | init_task.nsproxy->mnt_ns = ns; | |
2267 | get_mnt_ns(ns); | |
2268 | ||
ac748a09 JB |
2269 | root.mnt = ns->root; |
2270 | root.dentry = ns->root->mnt_root; | |
2271 | ||
2272 | set_fs_pwd(current->fs, &root); | |
2273 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
2274 | } |
2275 | ||
74bf17cf | 2276 | void __init mnt_init(void) |
1da177e4 | 2277 | { |
13f14b4d | 2278 | unsigned u; |
15a67dd8 | 2279 | int err; |
1da177e4 | 2280 | |
390c6843 RP |
2281 | init_rwsem(&namespace_sem); |
2282 | ||
1da177e4 | 2283 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount), |
20c2df83 | 2284 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 2285 | |
b58fed8b | 2286 | mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); |
1da177e4 LT |
2287 | |
2288 | if (!mount_hashtable) | |
2289 | panic("Failed to allocate mount hash table\n"); | |
2290 | ||
13f14b4d ED |
2291 | printk("Mount-cache hash table entries: %lu\n", HASH_SIZE); |
2292 | ||
2293 | for (u = 0; u < HASH_SIZE; u++) | |
2294 | INIT_LIST_HEAD(&mount_hashtable[u]); | |
1da177e4 | 2295 | |
15a67dd8 RD |
2296 | err = sysfs_init(); |
2297 | if (err) | |
2298 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 2299 | __func__, err); |
00d26666 GKH |
2300 | fs_kobj = kobject_create_and_add("fs", NULL); |
2301 | if (!fs_kobj) | |
8e24eea7 | 2302 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
2303 | init_rootfs(); |
2304 | init_mount_tree(); | |
2305 | } | |
2306 | ||
616511d0 | 2307 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 2308 | { |
616511d0 | 2309 | struct vfsmount *root; |
70fbcdf4 | 2310 | LIST_HEAD(umount_list); |
616511d0 TM |
2311 | |
2312 | if (!atomic_dec_and_lock(&ns->count, &vfsmount_lock)) | |
2313 | return; | |
2314 | root = ns->root; | |
6b3286ed | 2315 | ns->root = NULL; |
1ce88cf4 | 2316 | spin_unlock(&vfsmount_lock); |
390c6843 | 2317 | down_write(&namespace_sem); |
1da177e4 | 2318 | spin_lock(&vfsmount_lock); |
a05964f3 | 2319 | umount_tree(root, 0, &umount_list); |
1da177e4 | 2320 | spin_unlock(&vfsmount_lock); |
390c6843 | 2321 | up_write(&namespace_sem); |
70fbcdf4 | 2322 | release_mounts(&umount_list); |
6b3286ed | 2323 | kfree(ns); |
1da177e4 | 2324 | } |
cf8d2c11 | 2325 | EXPORT_SYMBOL(put_mnt_ns); |