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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 | 11 | #include <linux/syscalls.h> |
d10577a8 | 12 | #include <linux/export.h> |
16f7e0fe | 13 | #include <linux/capability.h> |
6b3286ed | 14 | #include <linux/mnt_namespace.h> |
771b1371 | 15 | #include <linux/user_namespace.h> |
1da177e4 LT |
16 | #include <linux/namei.h> |
17 | #include <linux/security.h> | |
73cd49ec | 18 | #include <linux/idr.h> |
d10577a8 | 19 | #include <linux/acct.h> /* acct_auto_close_mnt */ |
57f150a5 | 20 | #include <linux/init.h> /* init_rootfs */ |
d10577a8 AV |
21 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
22 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ | |
23 | #include <linux/uaccess.h> | |
0bb80f24 | 24 | #include <linux/proc_ns.h> |
20b4fb48 | 25 | #include <linux/magic.h> |
0818bf27 | 26 | #include <linux/bootmem.h> |
07b20889 | 27 | #include "pnode.h" |
948730b0 | 28 | #include "internal.h" |
1da177e4 | 29 | |
0818bf27 AV |
30 | static unsigned int m_hash_mask __read_mostly; |
31 | static unsigned int m_hash_shift __read_mostly; | |
32 | static unsigned int mp_hash_mask __read_mostly; | |
33 | static unsigned int mp_hash_shift __read_mostly; | |
34 | ||
35 | static __initdata unsigned long mhash_entries; | |
36 | static int __init set_mhash_entries(char *str) | |
37 | { | |
38 | if (!str) | |
39 | return 0; | |
40 | mhash_entries = simple_strtoul(str, &str, 0); | |
41 | return 1; | |
42 | } | |
43 | __setup("mhash_entries=", set_mhash_entries); | |
44 | ||
45 | static __initdata unsigned long mphash_entries; | |
46 | static int __init set_mphash_entries(char *str) | |
47 | { | |
48 | if (!str) | |
49 | return 0; | |
50 | mphash_entries = simple_strtoul(str, &str, 0); | |
51 | return 1; | |
52 | } | |
53 | __setup("mphash_entries=", set_mphash_entries); | |
13f14b4d | 54 | |
c7999c36 | 55 | static u64 event; |
73cd49ec | 56 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 57 | static DEFINE_IDA(mnt_group_ida); |
99b7db7b | 58 | static DEFINE_SPINLOCK(mnt_id_lock); |
f21f6220 AV |
59 | static int mnt_id_start = 0; |
60 | static int mnt_group_start = 1; | |
1da177e4 | 61 | |
38129a13 | 62 | static struct hlist_head *mount_hashtable __read_mostly; |
0818bf27 | 63 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
e18b890b | 64 | static struct kmem_cache *mnt_cache __read_mostly; |
59aa0da8 | 65 | static DECLARE_RWSEM(namespace_sem); |
1da177e4 | 66 | |
f87fd4c2 | 67 | /* /sys/fs */ |
00d26666 GKH |
68 | struct kobject *fs_kobj; |
69 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 70 | |
99b7db7b NP |
71 | /* |
72 | * vfsmount lock may be taken for read to prevent changes to the | |
73 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
74 | * up the tree. | |
75 | * | |
76 | * It should be taken for write in all cases where the vfsmount | |
77 | * tree or hash is modified or when a vfsmount structure is modified. | |
78 | */ | |
48a066e7 | 79 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
99b7db7b | 80 | |
38129a13 | 81 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 82 | { |
b58fed8b RP |
83 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
84 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
0818bf27 AV |
85 | tmp = tmp + (tmp >> m_hash_shift); |
86 | return &mount_hashtable[tmp & m_hash_mask]; | |
87 | } | |
88 | ||
89 | static inline struct hlist_head *mp_hash(struct dentry *dentry) | |
90 | { | |
91 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); | |
92 | tmp = tmp + (tmp >> mp_hash_shift); | |
93 | return &mountpoint_hashtable[tmp & mp_hash_mask]; | |
1da177e4 LT |
94 | } |
95 | ||
99b7db7b NP |
96 | /* |
97 | * allocation is serialized by namespace_sem, but we need the spinlock to | |
98 | * serialize with freeing. | |
99 | */ | |
b105e270 | 100 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec MS |
101 | { |
102 | int res; | |
103 | ||
104 | retry: | |
105 | ida_pre_get(&mnt_id_ida, GFP_KERNEL); | |
99b7db7b | 106 | spin_lock(&mnt_id_lock); |
15169fe7 | 107 | res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id); |
f21f6220 | 108 | if (!res) |
15169fe7 | 109 | mnt_id_start = mnt->mnt_id + 1; |
99b7db7b | 110 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
111 | if (res == -EAGAIN) |
112 | goto retry; | |
113 | ||
114 | return res; | |
115 | } | |
116 | ||
b105e270 | 117 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 118 | { |
15169fe7 | 119 | int id = mnt->mnt_id; |
99b7db7b | 120 | spin_lock(&mnt_id_lock); |
f21f6220 AV |
121 | ida_remove(&mnt_id_ida, id); |
122 | if (mnt_id_start > id) | |
123 | mnt_id_start = id; | |
99b7db7b | 124 | spin_unlock(&mnt_id_lock); |
73cd49ec MS |
125 | } |
126 | ||
719f5d7f MS |
127 | /* |
128 | * Allocate a new peer group ID | |
129 | * | |
130 | * mnt_group_ida is protected by namespace_sem | |
131 | */ | |
4b8b21f4 | 132 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 133 | { |
f21f6220 AV |
134 | int res; |
135 | ||
719f5d7f MS |
136 | if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) |
137 | return -ENOMEM; | |
138 | ||
f21f6220 AV |
139 | res = ida_get_new_above(&mnt_group_ida, |
140 | mnt_group_start, | |
15169fe7 | 141 | &mnt->mnt_group_id); |
f21f6220 | 142 | if (!res) |
15169fe7 | 143 | mnt_group_start = mnt->mnt_group_id + 1; |
f21f6220 AV |
144 | |
145 | return res; | |
719f5d7f MS |
146 | } |
147 | ||
148 | /* | |
149 | * Release a peer group ID | |
150 | */ | |
4b8b21f4 | 151 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 152 | { |
15169fe7 | 153 | int id = mnt->mnt_group_id; |
f21f6220 AV |
154 | ida_remove(&mnt_group_ida, id); |
155 | if (mnt_group_start > id) | |
156 | mnt_group_start = id; | |
15169fe7 | 157 | mnt->mnt_group_id = 0; |
719f5d7f MS |
158 | } |
159 | ||
b3e19d92 NP |
160 | /* |
161 | * vfsmount lock must be held for read | |
162 | */ | |
83adc753 | 163 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
164 | { |
165 | #ifdef CONFIG_SMP | |
68e8a9fe | 166 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
167 | #else |
168 | preempt_disable(); | |
68e8a9fe | 169 | mnt->mnt_count += n; |
b3e19d92 NP |
170 | preempt_enable(); |
171 | #endif | |
172 | } | |
173 | ||
b3e19d92 NP |
174 | /* |
175 | * vfsmount lock must be held for write | |
176 | */ | |
83adc753 | 177 | unsigned int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
178 | { |
179 | #ifdef CONFIG_SMP | |
f03c6599 | 180 | unsigned int count = 0; |
b3e19d92 NP |
181 | int cpu; |
182 | ||
183 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 184 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
185 | } |
186 | ||
187 | return count; | |
188 | #else | |
68e8a9fe | 189 | return mnt->mnt_count; |
b3e19d92 NP |
190 | #endif |
191 | } | |
192 | ||
b105e270 | 193 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 194 | { |
c63181e6 AV |
195 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
196 | if (mnt) { | |
73cd49ec MS |
197 | int err; |
198 | ||
c63181e6 | 199 | err = mnt_alloc_id(mnt); |
88b38782 LZ |
200 | if (err) |
201 | goto out_free_cache; | |
202 | ||
203 | if (name) { | |
c63181e6 AV |
204 | mnt->mnt_devname = kstrdup(name, GFP_KERNEL); |
205 | if (!mnt->mnt_devname) | |
88b38782 | 206 | goto out_free_id; |
73cd49ec MS |
207 | } |
208 | ||
b3e19d92 | 209 | #ifdef CONFIG_SMP |
c63181e6 AV |
210 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
211 | if (!mnt->mnt_pcp) | |
b3e19d92 NP |
212 | goto out_free_devname; |
213 | ||
c63181e6 | 214 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
b3e19d92 | 215 | #else |
c63181e6 AV |
216 | mnt->mnt_count = 1; |
217 | mnt->mnt_writers = 0; | |
b3e19d92 NP |
218 | #endif |
219 | ||
38129a13 | 220 | INIT_HLIST_NODE(&mnt->mnt_hash); |
c63181e6 AV |
221 | INIT_LIST_HEAD(&mnt->mnt_child); |
222 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
223 | INIT_LIST_HEAD(&mnt->mnt_list); | |
224 | INIT_LIST_HEAD(&mnt->mnt_expire); | |
225 | INIT_LIST_HEAD(&mnt->mnt_share); | |
226 | INIT_LIST_HEAD(&mnt->mnt_slave_list); | |
227 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
2504c5d6 AG |
228 | #ifdef CONFIG_FSNOTIFY |
229 | INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks); | |
d3ef3d73 | 230 | #endif |
1da177e4 | 231 | } |
c63181e6 | 232 | return mnt; |
88b38782 | 233 | |
d3ef3d73 | 234 | #ifdef CONFIG_SMP |
235 | out_free_devname: | |
c63181e6 | 236 | kfree(mnt->mnt_devname); |
d3ef3d73 | 237 | #endif |
88b38782 | 238 | out_free_id: |
c63181e6 | 239 | mnt_free_id(mnt); |
88b38782 | 240 | out_free_cache: |
c63181e6 | 241 | kmem_cache_free(mnt_cache, mnt); |
88b38782 | 242 | return NULL; |
1da177e4 LT |
243 | } |
244 | ||
3d733633 DH |
245 | /* |
246 | * Most r/o checks on a fs are for operations that take | |
247 | * discrete amounts of time, like a write() or unlink(). | |
248 | * We must keep track of when those operations start | |
249 | * (for permission checks) and when they end, so that | |
250 | * we can determine when writes are able to occur to | |
251 | * a filesystem. | |
252 | */ | |
253 | /* | |
254 | * __mnt_is_readonly: check whether a mount is read-only | |
255 | * @mnt: the mount to check for its write status | |
256 | * | |
257 | * This shouldn't be used directly ouside of the VFS. | |
258 | * It does not guarantee that the filesystem will stay | |
259 | * r/w, just that it is right *now*. This can not and | |
260 | * should not be used in place of IS_RDONLY(inode). | |
261 | * mnt_want/drop_write() will _keep_ the filesystem | |
262 | * r/w. | |
263 | */ | |
264 | int __mnt_is_readonly(struct vfsmount *mnt) | |
265 | { | |
2e4b7fcd DH |
266 | if (mnt->mnt_flags & MNT_READONLY) |
267 | return 1; | |
268 | if (mnt->mnt_sb->s_flags & MS_RDONLY) | |
269 | return 1; | |
270 | return 0; | |
3d733633 DH |
271 | } |
272 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
273 | ||
83adc753 | 274 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 | 275 | { |
276 | #ifdef CONFIG_SMP | |
68e8a9fe | 277 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 278 | #else |
68e8a9fe | 279 | mnt->mnt_writers++; |
d3ef3d73 | 280 | #endif |
281 | } | |
3d733633 | 282 | |
83adc753 | 283 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 284 | { |
d3ef3d73 | 285 | #ifdef CONFIG_SMP |
68e8a9fe | 286 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 287 | #else |
68e8a9fe | 288 | mnt->mnt_writers--; |
d3ef3d73 | 289 | #endif |
3d733633 | 290 | } |
3d733633 | 291 | |
83adc753 | 292 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 293 | { |
d3ef3d73 | 294 | #ifdef CONFIG_SMP |
295 | unsigned int count = 0; | |
3d733633 | 296 | int cpu; |
3d733633 DH |
297 | |
298 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 299 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 300 | } |
3d733633 | 301 | |
d3ef3d73 | 302 | return count; |
303 | #else | |
304 | return mnt->mnt_writers; | |
305 | #endif | |
3d733633 DH |
306 | } |
307 | ||
4ed5e82f MS |
308 | static int mnt_is_readonly(struct vfsmount *mnt) |
309 | { | |
310 | if (mnt->mnt_sb->s_readonly_remount) | |
311 | return 1; | |
312 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ | |
313 | smp_rmb(); | |
314 | return __mnt_is_readonly(mnt); | |
315 | } | |
316 | ||
8366025e | 317 | /* |
eb04c282 JK |
318 | * Most r/o & frozen checks on a fs are for operations that take discrete |
319 | * amounts of time, like a write() or unlink(). We must keep track of when | |
320 | * those operations start (for permission checks) and when they end, so that we | |
321 | * can determine when writes are able to occur to a filesystem. | |
8366025e DH |
322 | */ |
323 | /** | |
eb04c282 | 324 | * __mnt_want_write - get write access to a mount without freeze protection |
83adc753 | 325 | * @m: the mount on which to take a write |
8366025e | 326 | * |
eb04c282 JK |
327 | * This tells the low-level filesystem that a write is about to be performed to |
328 | * it, and makes sure that writes are allowed (mnt it read-write) before | |
329 | * returning success. This operation does not protect against filesystem being | |
330 | * frozen. When the write operation is finished, __mnt_drop_write() must be | |
331 | * called. This is effectively a refcount. | |
8366025e | 332 | */ |
eb04c282 | 333 | int __mnt_want_write(struct vfsmount *m) |
8366025e | 334 | { |
83adc753 | 335 | struct mount *mnt = real_mount(m); |
3d733633 | 336 | int ret = 0; |
3d733633 | 337 | |
d3ef3d73 | 338 | preempt_disable(); |
c6653a83 | 339 | mnt_inc_writers(mnt); |
d3ef3d73 | 340 | /* |
c6653a83 | 341 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 | 342 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
343 | * incremented count after it has set MNT_WRITE_HOLD. | |
344 | */ | |
345 | smp_mb(); | |
1e75529e | 346 | while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) |
d3ef3d73 | 347 | cpu_relax(); |
348 | /* | |
349 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
350 | * be set to match its requirements. So we must not load that until | |
351 | * MNT_WRITE_HOLD is cleared. | |
352 | */ | |
353 | smp_rmb(); | |
4ed5e82f | 354 | if (mnt_is_readonly(m)) { |
c6653a83 | 355 | mnt_dec_writers(mnt); |
3d733633 | 356 | ret = -EROFS; |
3d733633 | 357 | } |
d3ef3d73 | 358 | preempt_enable(); |
eb04c282 JK |
359 | |
360 | return ret; | |
361 | } | |
362 | ||
363 | /** | |
364 | * mnt_want_write - get write access to a mount | |
365 | * @m: the mount on which to take a write | |
366 | * | |
367 | * This tells the low-level filesystem that a write is about to be performed to | |
368 | * it, and makes sure that writes are allowed (mount is read-write, filesystem | |
369 | * is not frozen) before returning success. When the write operation is | |
370 | * finished, mnt_drop_write() must be called. This is effectively a refcount. | |
371 | */ | |
372 | int mnt_want_write(struct vfsmount *m) | |
373 | { | |
374 | int ret; | |
375 | ||
376 | sb_start_write(m->mnt_sb); | |
377 | ret = __mnt_want_write(m); | |
378 | if (ret) | |
379 | sb_end_write(m->mnt_sb); | |
3d733633 | 380 | return ret; |
8366025e DH |
381 | } |
382 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
383 | ||
96029c4e | 384 | /** |
385 | * mnt_clone_write - get write access to a mount | |
386 | * @mnt: the mount on which to take a write | |
387 | * | |
388 | * This is effectively like mnt_want_write, except | |
389 | * it must only be used to take an extra write reference | |
390 | * on a mountpoint that we already know has a write reference | |
391 | * on it. This allows some optimisation. | |
392 | * | |
393 | * After finished, mnt_drop_write must be called as usual to | |
394 | * drop the reference. | |
395 | */ | |
396 | int mnt_clone_write(struct vfsmount *mnt) | |
397 | { | |
398 | /* superblock may be r/o */ | |
399 | if (__mnt_is_readonly(mnt)) | |
400 | return -EROFS; | |
401 | preempt_disable(); | |
83adc753 | 402 | mnt_inc_writers(real_mount(mnt)); |
96029c4e | 403 | preempt_enable(); |
404 | return 0; | |
405 | } | |
406 | EXPORT_SYMBOL_GPL(mnt_clone_write); | |
407 | ||
408 | /** | |
eb04c282 | 409 | * __mnt_want_write_file - get write access to a file's mount |
96029c4e | 410 | * @file: the file who's mount on which to take a write |
411 | * | |
eb04c282 | 412 | * This is like __mnt_want_write, but it takes a file and can |
96029c4e | 413 | * do some optimisations if the file is open for write already |
414 | */ | |
eb04c282 | 415 | int __mnt_want_write_file(struct file *file) |
96029c4e | 416 | { |
496ad9aa | 417 | struct inode *inode = file_inode(file); |
eb04c282 | 418 | |
2d8dd38a | 419 | if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) |
eb04c282 | 420 | return __mnt_want_write(file->f_path.mnt); |
96029c4e | 421 | else |
422 | return mnt_clone_write(file->f_path.mnt); | |
423 | } | |
eb04c282 JK |
424 | |
425 | /** | |
426 | * mnt_want_write_file - get write access to a file's mount | |
427 | * @file: the file who's mount on which to take a write | |
428 | * | |
429 | * This is like mnt_want_write, but it takes a file and can | |
430 | * do some optimisations if the file is open for write already | |
431 | */ | |
432 | int mnt_want_write_file(struct file *file) | |
433 | { | |
434 | int ret; | |
435 | ||
436 | sb_start_write(file->f_path.mnt->mnt_sb); | |
437 | ret = __mnt_want_write_file(file); | |
438 | if (ret) | |
439 | sb_end_write(file->f_path.mnt->mnt_sb); | |
440 | return ret; | |
441 | } | |
96029c4e | 442 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
443 | ||
8366025e | 444 | /** |
eb04c282 | 445 | * __mnt_drop_write - give up write access to a mount |
8366025e DH |
446 | * @mnt: the mount on which to give up write access |
447 | * | |
448 | * Tells the low-level filesystem that we are done | |
449 | * performing writes to it. Must be matched with | |
eb04c282 | 450 | * __mnt_want_write() call above. |
8366025e | 451 | */ |
eb04c282 | 452 | void __mnt_drop_write(struct vfsmount *mnt) |
8366025e | 453 | { |
d3ef3d73 | 454 | preempt_disable(); |
83adc753 | 455 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 456 | preempt_enable(); |
8366025e | 457 | } |
eb04c282 JK |
458 | |
459 | /** | |
460 | * mnt_drop_write - give up write access to a mount | |
461 | * @mnt: the mount on which to give up write access | |
462 | * | |
463 | * Tells the low-level filesystem that we are done performing writes to it and | |
464 | * also allows filesystem to be frozen again. Must be matched with | |
465 | * mnt_want_write() call above. | |
466 | */ | |
467 | void mnt_drop_write(struct vfsmount *mnt) | |
468 | { | |
469 | __mnt_drop_write(mnt); | |
470 | sb_end_write(mnt->mnt_sb); | |
471 | } | |
8366025e DH |
472 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
473 | ||
eb04c282 JK |
474 | void __mnt_drop_write_file(struct file *file) |
475 | { | |
476 | __mnt_drop_write(file->f_path.mnt); | |
477 | } | |
478 | ||
2a79f17e AV |
479 | void mnt_drop_write_file(struct file *file) |
480 | { | |
481 | mnt_drop_write(file->f_path.mnt); | |
482 | } | |
483 | EXPORT_SYMBOL(mnt_drop_write_file); | |
484 | ||
83adc753 | 485 | static int mnt_make_readonly(struct mount *mnt) |
8366025e | 486 | { |
3d733633 DH |
487 | int ret = 0; |
488 | ||
719ea2fb | 489 | lock_mount_hash(); |
83adc753 | 490 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 491 | /* |
d3ef3d73 | 492 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
493 | * should be visible before we do. | |
3d733633 | 494 | */ |
d3ef3d73 | 495 | smp_mb(); |
496 | ||
3d733633 | 497 | /* |
d3ef3d73 | 498 | * With writers on hold, if this value is zero, then there are |
499 | * definitely no active writers (although held writers may subsequently | |
500 | * increment the count, they'll have to wait, and decrement it after | |
501 | * seeing MNT_READONLY). | |
502 | * | |
503 | * It is OK to have counter incremented on one CPU and decremented on | |
504 | * another: the sum will add up correctly. The danger would be when we | |
505 | * sum up each counter, if we read a counter before it is incremented, | |
506 | * but then read another CPU's count which it has been subsequently | |
507 | * decremented from -- we would see more decrements than we should. | |
508 | * MNT_WRITE_HOLD protects against this scenario, because | |
509 | * mnt_want_write first increments count, then smp_mb, then spins on | |
510 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
511 | * we're counting up here. | |
3d733633 | 512 | */ |
c6653a83 | 513 | if (mnt_get_writers(mnt) > 0) |
d3ef3d73 | 514 | ret = -EBUSY; |
515 | else | |
83adc753 | 516 | mnt->mnt.mnt_flags |= MNT_READONLY; |
d3ef3d73 | 517 | /* |
518 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
519 | * that become unheld will see MNT_READONLY. | |
520 | */ | |
521 | smp_wmb(); | |
83adc753 | 522 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
719ea2fb | 523 | unlock_mount_hash(); |
3d733633 | 524 | return ret; |
8366025e | 525 | } |
8366025e | 526 | |
83adc753 | 527 | static void __mnt_unmake_readonly(struct mount *mnt) |
2e4b7fcd | 528 | { |
719ea2fb | 529 | lock_mount_hash(); |
83adc753 | 530 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
719ea2fb | 531 | unlock_mount_hash(); |
2e4b7fcd DH |
532 | } |
533 | ||
4ed5e82f MS |
534 | int sb_prepare_remount_readonly(struct super_block *sb) |
535 | { | |
536 | struct mount *mnt; | |
537 | int err = 0; | |
538 | ||
8e8b8796 MS |
539 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
540 | if (atomic_long_read(&sb->s_remove_count)) | |
541 | return -EBUSY; | |
542 | ||
719ea2fb | 543 | lock_mount_hash(); |
4ed5e82f MS |
544 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
545 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { | |
546 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; | |
547 | smp_mb(); | |
548 | if (mnt_get_writers(mnt) > 0) { | |
549 | err = -EBUSY; | |
550 | break; | |
551 | } | |
552 | } | |
553 | } | |
8e8b8796 MS |
554 | if (!err && atomic_long_read(&sb->s_remove_count)) |
555 | err = -EBUSY; | |
556 | ||
4ed5e82f MS |
557 | if (!err) { |
558 | sb->s_readonly_remount = 1; | |
559 | smp_wmb(); | |
560 | } | |
561 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { | |
562 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) | |
563 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; | |
564 | } | |
719ea2fb | 565 | unlock_mount_hash(); |
4ed5e82f MS |
566 | |
567 | return err; | |
568 | } | |
569 | ||
b105e270 | 570 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 571 | { |
52ba1621 | 572 | kfree(mnt->mnt_devname); |
73cd49ec | 573 | mnt_free_id(mnt); |
d3ef3d73 | 574 | #ifdef CONFIG_SMP |
68e8a9fe | 575 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 576 | #endif |
b105e270 | 577 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
578 | } |
579 | ||
48a066e7 AV |
580 | /* call under rcu_read_lock */ |
581 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) | |
582 | { | |
583 | struct mount *mnt; | |
584 | if (read_seqretry(&mount_lock, seq)) | |
585 | return false; | |
586 | if (bastard == NULL) | |
587 | return true; | |
588 | mnt = real_mount(bastard); | |
589 | mnt_add_count(mnt, 1); | |
590 | if (likely(!read_seqretry(&mount_lock, seq))) | |
591 | return true; | |
592 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { | |
593 | mnt_add_count(mnt, -1); | |
594 | return false; | |
595 | } | |
596 | rcu_read_unlock(); | |
597 | mntput(bastard); | |
598 | rcu_read_lock(); | |
599 | return false; | |
600 | } | |
601 | ||
1da177e4 | 602 | /* |
474279dc | 603 | * find the first mount at @dentry on vfsmount @mnt. |
48a066e7 | 604 | * call under rcu_read_lock() |
1da177e4 | 605 | */ |
474279dc | 606 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 607 | { |
38129a13 | 608 | struct hlist_head *head = m_hash(mnt, dentry); |
474279dc AV |
609 | struct mount *p; |
610 | ||
38129a13 | 611 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
474279dc AV |
612 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
613 | return p; | |
614 | return NULL; | |
615 | } | |
616 | ||
617 | /* | |
618 | * find the last mount at @dentry on vfsmount @mnt. | |
48a066e7 | 619 | * mount_lock must be held. |
474279dc AV |
620 | */ |
621 | struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry) | |
622 | { | |
38129a13 AV |
623 | struct mount *p, *res; |
624 | res = p = __lookup_mnt(mnt, dentry); | |
625 | if (!p) | |
626 | goto out; | |
627 | hlist_for_each_entry_continue(p, mnt_hash) { | |
1d6a32ac AV |
628 | if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry) |
629 | break; | |
630 | res = p; | |
631 | } | |
38129a13 | 632 | out: |
1d6a32ac | 633 | return res; |
1da177e4 LT |
634 | } |
635 | ||
a05964f3 | 636 | /* |
f015f126 DH |
637 | * lookup_mnt - Return the first child mount mounted at path |
638 | * | |
639 | * "First" means first mounted chronologically. If you create the | |
640 | * following mounts: | |
641 | * | |
642 | * mount /dev/sda1 /mnt | |
643 | * mount /dev/sda2 /mnt | |
644 | * mount /dev/sda3 /mnt | |
645 | * | |
646 | * Then lookup_mnt() on the base /mnt dentry in the root mount will | |
647 | * return successively the root dentry and vfsmount of /dev/sda1, then | |
648 | * /dev/sda2, then /dev/sda3, then NULL. | |
649 | * | |
650 | * lookup_mnt takes a reference to the found vfsmount. | |
a05964f3 | 651 | */ |
1c755af4 | 652 | struct vfsmount *lookup_mnt(struct path *path) |
a05964f3 | 653 | { |
c7105365 | 654 | struct mount *child_mnt; |
48a066e7 AV |
655 | struct vfsmount *m; |
656 | unsigned seq; | |
99b7db7b | 657 | |
48a066e7 AV |
658 | rcu_read_lock(); |
659 | do { | |
660 | seq = read_seqbegin(&mount_lock); | |
661 | child_mnt = __lookup_mnt(path->mnt, path->dentry); | |
662 | m = child_mnt ? &child_mnt->mnt : NULL; | |
663 | } while (!legitimize_mnt(m, seq)); | |
664 | rcu_read_unlock(); | |
665 | return m; | |
a05964f3 RP |
666 | } |
667 | ||
84d17192 AV |
668 | static struct mountpoint *new_mountpoint(struct dentry *dentry) |
669 | { | |
0818bf27 | 670 | struct hlist_head *chain = mp_hash(dentry); |
84d17192 | 671 | struct mountpoint *mp; |
eed81007 | 672 | int ret; |
84d17192 | 673 | |
0818bf27 | 674 | hlist_for_each_entry(mp, chain, m_hash) { |
84d17192 AV |
675 | if (mp->m_dentry == dentry) { |
676 | /* might be worth a WARN_ON() */ | |
677 | if (d_unlinked(dentry)) | |
678 | return ERR_PTR(-ENOENT); | |
679 | mp->m_count++; | |
680 | return mp; | |
681 | } | |
682 | } | |
683 | ||
684 | mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); | |
685 | if (!mp) | |
686 | return ERR_PTR(-ENOMEM); | |
687 | ||
eed81007 MS |
688 | ret = d_set_mounted(dentry); |
689 | if (ret) { | |
84d17192 | 690 | kfree(mp); |
eed81007 | 691 | return ERR_PTR(ret); |
84d17192 | 692 | } |
eed81007 | 693 | |
84d17192 AV |
694 | mp->m_dentry = dentry; |
695 | mp->m_count = 1; | |
0818bf27 | 696 | hlist_add_head(&mp->m_hash, chain); |
84d17192 AV |
697 | return mp; |
698 | } | |
699 | ||
700 | static void put_mountpoint(struct mountpoint *mp) | |
701 | { | |
702 | if (!--mp->m_count) { | |
703 | struct dentry *dentry = mp->m_dentry; | |
704 | spin_lock(&dentry->d_lock); | |
705 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
706 | spin_unlock(&dentry->d_lock); | |
0818bf27 | 707 | hlist_del(&mp->m_hash); |
84d17192 AV |
708 | kfree(mp); |
709 | } | |
710 | } | |
711 | ||
143c8c91 | 712 | static inline int check_mnt(struct mount *mnt) |
1da177e4 | 713 | { |
6b3286ed | 714 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
715 | } |
716 | ||
99b7db7b NP |
717 | /* |
718 | * vfsmount lock must be held for write | |
719 | */ | |
6b3286ed | 720 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
721 | { |
722 | if (ns) { | |
723 | ns->event = ++event; | |
724 | wake_up_interruptible(&ns->poll); | |
725 | } | |
726 | } | |
727 | ||
99b7db7b NP |
728 | /* |
729 | * vfsmount lock must be held for write | |
730 | */ | |
6b3286ed | 731 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
732 | { |
733 | if (ns && ns->event != event) { | |
734 | ns->event = event; | |
735 | wake_up_interruptible(&ns->poll); | |
736 | } | |
737 | } | |
738 | ||
99b7db7b NP |
739 | /* |
740 | * vfsmount lock must be held for write | |
741 | */ | |
419148da AV |
742 | static void detach_mnt(struct mount *mnt, struct path *old_path) |
743 | { | |
a73324da | 744 | old_path->dentry = mnt->mnt_mountpoint; |
0714a533 AV |
745 | old_path->mnt = &mnt->mnt_parent->mnt; |
746 | mnt->mnt_parent = mnt; | |
a73324da | 747 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 748 | list_del_init(&mnt->mnt_child); |
38129a13 | 749 | hlist_del_init_rcu(&mnt->mnt_hash); |
84d17192 AV |
750 | put_mountpoint(mnt->mnt_mp); |
751 | mnt->mnt_mp = NULL; | |
1da177e4 LT |
752 | } |
753 | ||
99b7db7b NP |
754 | /* |
755 | * vfsmount lock must be held for write | |
756 | */ | |
84d17192 AV |
757 | void mnt_set_mountpoint(struct mount *mnt, |
758 | struct mountpoint *mp, | |
44d964d6 | 759 | struct mount *child_mnt) |
b90fa9ae | 760 | { |
84d17192 | 761 | mp->m_count++; |
3a2393d7 | 762 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
84d17192 | 763 | child_mnt->mnt_mountpoint = dget(mp->m_dentry); |
3a2393d7 | 764 | child_mnt->mnt_parent = mnt; |
84d17192 | 765 | child_mnt->mnt_mp = mp; |
b90fa9ae RP |
766 | } |
767 | ||
99b7db7b NP |
768 | /* |
769 | * vfsmount lock must be held for write | |
770 | */ | |
84d17192 AV |
771 | static void attach_mnt(struct mount *mnt, |
772 | struct mount *parent, | |
773 | struct mountpoint *mp) | |
1da177e4 | 774 | { |
84d17192 | 775 | mnt_set_mountpoint(parent, mp, mnt); |
38129a13 | 776 | hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry)); |
84d17192 | 777 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
b90fa9ae RP |
778 | } |
779 | ||
780 | /* | |
99b7db7b | 781 | * vfsmount lock must be held for write |
b90fa9ae | 782 | */ |
1d6a32ac | 783 | static void commit_tree(struct mount *mnt, struct mount *shadows) |
b90fa9ae | 784 | { |
0714a533 | 785 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 786 | struct mount *m; |
b90fa9ae | 787 | LIST_HEAD(head); |
143c8c91 | 788 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae | 789 | |
0714a533 | 790 | BUG_ON(parent == mnt); |
b90fa9ae | 791 | |
1a4eeaf2 | 792 | list_add_tail(&head, &mnt->mnt_list); |
f7a99c5b | 793 | list_for_each_entry(m, &head, mnt_list) |
143c8c91 | 794 | m->mnt_ns = n; |
f03c6599 | 795 | |
b90fa9ae RP |
796 | list_splice(&head, n->list.prev); |
797 | ||
1d6a32ac | 798 | if (shadows) |
38129a13 | 799 | hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash); |
1d6a32ac | 800 | else |
38129a13 | 801 | hlist_add_head_rcu(&mnt->mnt_hash, |
0818bf27 | 802 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); |
6b41d536 | 803 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
6b3286ed | 804 | touch_mnt_namespace(n); |
1da177e4 LT |
805 | } |
806 | ||
909b0a88 | 807 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
1da177e4 | 808 | { |
6b41d536 AV |
809 | struct list_head *next = p->mnt_mounts.next; |
810 | if (next == &p->mnt_mounts) { | |
1da177e4 | 811 | while (1) { |
909b0a88 | 812 | if (p == root) |
1da177e4 | 813 | return NULL; |
6b41d536 AV |
814 | next = p->mnt_child.next; |
815 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 816 | break; |
0714a533 | 817 | p = p->mnt_parent; |
1da177e4 LT |
818 | } |
819 | } | |
6b41d536 | 820 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
821 | } |
822 | ||
315fc83e | 823 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 824 | { |
6b41d536 AV |
825 | struct list_head *prev = p->mnt_mounts.prev; |
826 | while (prev != &p->mnt_mounts) { | |
827 | p = list_entry(prev, struct mount, mnt_child); | |
828 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
829 | } |
830 | return p; | |
831 | } | |
832 | ||
9d412a43 AV |
833 | struct vfsmount * |
834 | vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data) | |
835 | { | |
b105e270 | 836 | struct mount *mnt; |
9d412a43 AV |
837 | struct dentry *root; |
838 | ||
839 | if (!type) | |
840 | return ERR_PTR(-ENODEV); | |
841 | ||
842 | mnt = alloc_vfsmnt(name); | |
843 | if (!mnt) | |
844 | return ERR_PTR(-ENOMEM); | |
845 | ||
846 | if (flags & MS_KERNMOUNT) | |
b105e270 | 847 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 AV |
848 | |
849 | root = mount_fs(type, flags, name, data); | |
850 | if (IS_ERR(root)) { | |
851 | free_vfsmnt(mnt); | |
852 | return ERR_CAST(root); | |
853 | } | |
854 | ||
b105e270 AV |
855 | mnt->mnt.mnt_root = root; |
856 | mnt->mnt.mnt_sb = root->d_sb; | |
a73324da | 857 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
0714a533 | 858 | mnt->mnt_parent = mnt; |
719ea2fb | 859 | lock_mount_hash(); |
39f7c4db | 860 | list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts); |
719ea2fb | 861 | unlock_mount_hash(); |
b105e270 | 862 | return &mnt->mnt; |
9d412a43 AV |
863 | } |
864 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
865 | ||
87129cc0 | 866 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 867 | int flag) |
1da177e4 | 868 | { |
87129cc0 | 869 | struct super_block *sb = old->mnt.mnt_sb; |
be34d1a3 DH |
870 | struct mount *mnt; |
871 | int err; | |
1da177e4 | 872 | |
be34d1a3 DH |
873 | mnt = alloc_vfsmnt(old->mnt_devname); |
874 | if (!mnt) | |
875 | return ERR_PTR(-ENOMEM); | |
719f5d7f | 876 | |
7a472ef4 | 877 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
be34d1a3 DH |
878 | mnt->mnt_group_id = 0; /* not a peer of original */ |
879 | else | |
880 | mnt->mnt_group_id = old->mnt_group_id; | |
b90fa9ae | 881 | |
be34d1a3 DH |
882 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
883 | err = mnt_alloc_group_id(mnt); | |
884 | if (err) | |
885 | goto out_free; | |
1da177e4 | 886 | } |
be34d1a3 | 887 | |
f2ebb3a9 | 888 | mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); |
132c94e3 EB |
889 | /* Don't allow unprivileged users to change mount flags */ |
890 | if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) | |
891 | mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; | |
892 | ||
5ff9d8a6 EB |
893 | /* Don't allow unprivileged users to reveal what is under a mount */ |
894 | if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire)) | |
895 | mnt->mnt.mnt_flags |= MNT_LOCKED; | |
896 | ||
be34d1a3 DH |
897 | atomic_inc(&sb->s_active); |
898 | mnt->mnt.mnt_sb = sb; | |
899 | mnt->mnt.mnt_root = dget(root); | |
900 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
901 | mnt->mnt_parent = mnt; | |
719ea2fb | 902 | lock_mount_hash(); |
be34d1a3 | 903 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
719ea2fb | 904 | unlock_mount_hash(); |
be34d1a3 | 905 | |
7a472ef4 EB |
906 | if ((flag & CL_SLAVE) || |
907 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { | |
be34d1a3 DH |
908 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
909 | mnt->mnt_master = old; | |
910 | CLEAR_MNT_SHARED(mnt); | |
911 | } else if (!(flag & CL_PRIVATE)) { | |
912 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) | |
913 | list_add(&mnt->mnt_share, &old->mnt_share); | |
914 | if (IS_MNT_SLAVE(old)) | |
915 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
916 | mnt->mnt_master = old->mnt_master; | |
917 | } | |
918 | if (flag & CL_MAKE_SHARED) | |
919 | set_mnt_shared(mnt); | |
920 | ||
921 | /* stick the duplicate mount on the same expiry list | |
922 | * as the original if that was on one */ | |
923 | if (flag & CL_EXPIRE) { | |
924 | if (!list_empty(&old->mnt_expire)) | |
925 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
926 | } | |
927 | ||
cb338d06 | 928 | return mnt; |
719f5d7f MS |
929 | |
930 | out_free: | |
931 | free_vfsmnt(mnt); | |
be34d1a3 | 932 | return ERR_PTR(err); |
1da177e4 LT |
933 | } |
934 | ||
48a066e7 AV |
935 | static void delayed_free(struct rcu_head *head) |
936 | { | |
937 | struct mount *mnt = container_of(head, struct mount, mnt_rcu); | |
938 | kfree(mnt->mnt_devname); | |
939 | #ifdef CONFIG_SMP | |
940 | free_percpu(mnt->mnt_pcp); | |
941 | #endif | |
942 | kmem_cache_free(mnt_cache, mnt); | |
943 | } | |
944 | ||
900148dc | 945 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 946 | { |
b3e19d92 | 947 | put_again: |
48a066e7 AV |
948 | rcu_read_lock(); |
949 | mnt_add_count(mnt, -1); | |
950 | if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */ | |
951 | rcu_read_unlock(); | |
f03c6599 | 952 | return; |
b3e19d92 | 953 | } |
719ea2fb | 954 | lock_mount_hash(); |
b3e19d92 | 955 | if (mnt_get_count(mnt)) { |
48a066e7 | 956 | rcu_read_unlock(); |
719ea2fb | 957 | unlock_mount_hash(); |
99b7db7b NP |
958 | return; |
959 | } | |
863d684f AV |
960 | if (unlikely(mnt->mnt_pinned)) { |
961 | mnt_add_count(mnt, mnt->mnt_pinned + 1); | |
962 | mnt->mnt_pinned = 0; | |
48a066e7 | 963 | rcu_read_unlock(); |
719ea2fb | 964 | unlock_mount_hash(); |
900148dc | 965 | acct_auto_close_mnt(&mnt->mnt); |
b3e19d92 | 966 | goto put_again; |
7b7b1ace | 967 | } |
48a066e7 AV |
968 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
969 | rcu_read_unlock(); | |
970 | unlock_mount_hash(); | |
971 | return; | |
972 | } | |
973 | mnt->mnt.mnt_flags |= MNT_DOOMED; | |
974 | rcu_read_unlock(); | |
962830df | 975 | |
39f7c4db | 976 | list_del(&mnt->mnt_instance); |
719ea2fb | 977 | unlock_mount_hash(); |
649a795a AV |
978 | |
979 | /* | |
980 | * This probably indicates that somebody messed | |
981 | * up a mnt_want/drop_write() pair. If this | |
982 | * happens, the filesystem was probably unable | |
983 | * to make r/w->r/o transitions. | |
984 | */ | |
985 | /* | |
986 | * The locking used to deal with mnt_count decrement provides barriers, | |
987 | * so mnt_get_writers() below is safe. | |
988 | */ | |
989 | WARN_ON(mnt_get_writers(mnt)); | |
990 | fsnotify_vfsmount_delete(&mnt->mnt); | |
991 | dput(mnt->mnt.mnt_root); | |
992 | deactivate_super(mnt->mnt.mnt_sb); | |
48a066e7 AV |
993 | mnt_free_id(mnt); |
994 | call_rcu(&mnt->mnt_rcu, delayed_free); | |
b3e19d92 | 995 | } |
b3e19d92 NP |
996 | |
997 | void mntput(struct vfsmount *mnt) | |
998 | { | |
999 | if (mnt) { | |
863d684f | 1000 | struct mount *m = real_mount(mnt); |
b3e19d92 | 1001 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
863d684f AV |
1002 | if (unlikely(m->mnt_expiry_mark)) |
1003 | m->mnt_expiry_mark = 0; | |
1004 | mntput_no_expire(m); | |
b3e19d92 NP |
1005 | } |
1006 | } | |
1007 | EXPORT_SYMBOL(mntput); | |
1008 | ||
1009 | struct vfsmount *mntget(struct vfsmount *mnt) | |
1010 | { | |
1011 | if (mnt) | |
83adc753 | 1012 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
1013 | return mnt; |
1014 | } | |
1015 | EXPORT_SYMBOL(mntget); | |
1016 | ||
7b7b1ace AV |
1017 | void mnt_pin(struct vfsmount *mnt) |
1018 | { | |
719ea2fb | 1019 | lock_mount_hash(); |
863d684f | 1020 | real_mount(mnt)->mnt_pinned++; |
719ea2fb | 1021 | unlock_mount_hash(); |
7b7b1ace | 1022 | } |
7b7b1ace AV |
1023 | EXPORT_SYMBOL(mnt_pin); |
1024 | ||
863d684f | 1025 | void mnt_unpin(struct vfsmount *m) |
7b7b1ace | 1026 | { |
863d684f | 1027 | struct mount *mnt = real_mount(m); |
719ea2fb | 1028 | lock_mount_hash(); |
7b7b1ace | 1029 | if (mnt->mnt_pinned) { |
863d684f | 1030 | mnt_add_count(mnt, 1); |
7b7b1ace AV |
1031 | mnt->mnt_pinned--; |
1032 | } | |
719ea2fb | 1033 | unlock_mount_hash(); |
7b7b1ace | 1034 | } |
7b7b1ace | 1035 | EXPORT_SYMBOL(mnt_unpin); |
1da177e4 | 1036 | |
b3b304a2 MS |
1037 | static inline void mangle(struct seq_file *m, const char *s) |
1038 | { | |
1039 | seq_escape(m, s, " \t\n\\"); | |
1040 | } | |
1041 | ||
1042 | /* | |
1043 | * Simple .show_options callback for filesystems which don't want to | |
1044 | * implement more complex mount option showing. | |
1045 | * | |
1046 | * See also save_mount_options(). | |
1047 | */ | |
34c80b1d | 1048 | int generic_show_options(struct seq_file *m, struct dentry *root) |
b3b304a2 | 1049 | { |
2a32cebd AV |
1050 | const char *options; |
1051 | ||
1052 | rcu_read_lock(); | |
34c80b1d | 1053 | options = rcu_dereference(root->d_sb->s_options); |
b3b304a2 MS |
1054 | |
1055 | if (options != NULL && options[0]) { | |
1056 | seq_putc(m, ','); | |
1057 | mangle(m, options); | |
1058 | } | |
2a32cebd | 1059 | rcu_read_unlock(); |
b3b304a2 MS |
1060 | |
1061 | return 0; | |
1062 | } | |
1063 | EXPORT_SYMBOL(generic_show_options); | |
1064 | ||
1065 | /* | |
1066 | * If filesystem uses generic_show_options(), this function should be | |
1067 | * called from the fill_super() callback. | |
1068 | * | |
1069 | * The .remount_fs callback usually needs to be handled in a special | |
1070 | * way, to make sure, that previous options are not overwritten if the | |
1071 | * remount fails. | |
1072 | * | |
1073 | * Also note, that if the filesystem's .remount_fs function doesn't | |
1074 | * reset all options to their default value, but changes only newly | |
1075 | * given options, then the displayed options will not reflect reality | |
1076 | * any more. | |
1077 | */ | |
1078 | void save_mount_options(struct super_block *sb, char *options) | |
1079 | { | |
2a32cebd AV |
1080 | BUG_ON(sb->s_options); |
1081 | rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL)); | |
b3b304a2 MS |
1082 | } |
1083 | EXPORT_SYMBOL(save_mount_options); | |
1084 | ||
2a32cebd AV |
1085 | void replace_mount_options(struct super_block *sb, char *options) |
1086 | { | |
1087 | char *old = sb->s_options; | |
1088 | rcu_assign_pointer(sb->s_options, options); | |
1089 | if (old) { | |
1090 | synchronize_rcu(); | |
1091 | kfree(old); | |
1092 | } | |
1093 | } | |
1094 | EXPORT_SYMBOL(replace_mount_options); | |
1095 | ||
a1a2c409 | 1096 | #ifdef CONFIG_PROC_FS |
0226f492 | 1097 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
1da177e4 LT |
1098 | static void *m_start(struct seq_file *m, loff_t *pos) |
1099 | { | |
6ce6e24e | 1100 | struct proc_mounts *p = proc_mounts(m); |
1da177e4 | 1101 | |
390c6843 | 1102 | down_read(&namespace_sem); |
c7999c36 AV |
1103 | if (p->cached_event == p->ns->event) { |
1104 | void *v = p->cached_mount; | |
1105 | if (*pos == p->cached_index) | |
1106 | return v; | |
1107 | if (*pos == p->cached_index + 1) { | |
1108 | v = seq_list_next(v, &p->ns->list, &p->cached_index); | |
1109 | return p->cached_mount = v; | |
1110 | } | |
1111 | } | |
1112 | ||
1113 | p->cached_event = p->ns->event; | |
1114 | p->cached_mount = seq_list_start(&p->ns->list, *pos); | |
1115 | p->cached_index = *pos; | |
1116 | return p->cached_mount; | |
1da177e4 LT |
1117 | } |
1118 | ||
1119 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
1120 | { | |
6ce6e24e | 1121 | struct proc_mounts *p = proc_mounts(m); |
b0765fb8 | 1122 | |
c7999c36 AV |
1123 | p->cached_mount = seq_list_next(v, &p->ns->list, pos); |
1124 | p->cached_index = *pos; | |
1125 | return p->cached_mount; | |
1da177e4 LT |
1126 | } |
1127 | ||
1128 | static void m_stop(struct seq_file *m, void *v) | |
1129 | { | |
390c6843 | 1130 | up_read(&namespace_sem); |
1da177e4 LT |
1131 | } |
1132 | ||
0226f492 | 1133 | static int m_show(struct seq_file *m, void *v) |
2d4d4864 | 1134 | { |
6ce6e24e | 1135 | struct proc_mounts *p = proc_mounts(m); |
1a4eeaf2 | 1136 | struct mount *r = list_entry(v, struct mount, mnt_list); |
0226f492 | 1137 | return p->show(m, &r->mnt); |
1da177e4 LT |
1138 | } |
1139 | ||
a1a2c409 | 1140 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1141 | .start = m_start, |
1142 | .next = m_next, | |
1143 | .stop = m_stop, | |
0226f492 | 1144 | .show = m_show, |
b4629fe2 | 1145 | }; |
a1a2c409 | 1146 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1147 | |
1da177e4 LT |
1148 | /** |
1149 | * may_umount_tree - check if a mount tree is busy | |
1150 | * @mnt: root of mount tree | |
1151 | * | |
1152 | * This is called to check if a tree of mounts has any | |
1153 | * open files, pwds, chroots or sub mounts that are | |
1154 | * busy. | |
1155 | */ | |
909b0a88 | 1156 | int may_umount_tree(struct vfsmount *m) |
1da177e4 | 1157 | { |
909b0a88 | 1158 | struct mount *mnt = real_mount(m); |
36341f64 RP |
1159 | int actual_refs = 0; |
1160 | int minimum_refs = 0; | |
315fc83e | 1161 | struct mount *p; |
909b0a88 | 1162 | BUG_ON(!m); |
1da177e4 | 1163 | |
b3e19d92 | 1164 | /* write lock needed for mnt_get_count */ |
719ea2fb | 1165 | lock_mount_hash(); |
909b0a88 | 1166 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
83adc753 | 1167 | actual_refs += mnt_get_count(p); |
1da177e4 | 1168 | minimum_refs += 2; |
1da177e4 | 1169 | } |
719ea2fb | 1170 | unlock_mount_hash(); |
1da177e4 LT |
1171 | |
1172 | if (actual_refs > minimum_refs) | |
e3474a8e | 1173 | return 0; |
1da177e4 | 1174 | |
e3474a8e | 1175 | return 1; |
1da177e4 LT |
1176 | } |
1177 | ||
1178 | EXPORT_SYMBOL(may_umount_tree); | |
1179 | ||
1180 | /** | |
1181 | * may_umount - check if a mount point is busy | |
1182 | * @mnt: root of mount | |
1183 | * | |
1184 | * This is called to check if a mount point has any | |
1185 | * open files, pwds, chroots or sub mounts. If the | |
1186 | * mount has sub mounts this will return busy | |
1187 | * regardless of whether the sub mounts are busy. | |
1188 | * | |
1189 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1190 | * give false negatives. The main reason why it's here is that we need | |
1191 | * a non-destructive way to look for easily umountable filesystems. | |
1192 | */ | |
1193 | int may_umount(struct vfsmount *mnt) | |
1194 | { | |
e3474a8e | 1195 | int ret = 1; |
8ad08d8a | 1196 | down_read(&namespace_sem); |
719ea2fb | 1197 | lock_mount_hash(); |
1ab59738 | 1198 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1199 | ret = 0; |
719ea2fb | 1200 | unlock_mount_hash(); |
8ad08d8a | 1201 | up_read(&namespace_sem); |
a05964f3 | 1202 | return ret; |
1da177e4 LT |
1203 | } |
1204 | ||
1205 | EXPORT_SYMBOL(may_umount); | |
1206 | ||
38129a13 | 1207 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
e3197d83 | 1208 | |
97216be0 | 1209 | static void namespace_unlock(void) |
70fbcdf4 | 1210 | { |
d5e50f74 | 1211 | struct mount *mnt; |
38129a13 | 1212 | struct hlist_head head = unmounted; |
97216be0 | 1213 | |
38129a13 | 1214 | if (likely(hlist_empty(&head))) { |
97216be0 AV |
1215 | up_write(&namespace_sem); |
1216 | return; | |
1217 | } | |
1218 | ||
38129a13 AV |
1219 | head.first->pprev = &head.first; |
1220 | INIT_HLIST_HEAD(&unmounted); | |
1221 | ||
97216be0 AV |
1222 | up_write(&namespace_sem); |
1223 | ||
48a066e7 AV |
1224 | synchronize_rcu(); |
1225 | ||
38129a13 AV |
1226 | while (!hlist_empty(&head)) { |
1227 | mnt = hlist_entry(head.first, struct mount, mnt_hash); | |
1228 | hlist_del_init(&mnt->mnt_hash); | |
aba809cf AV |
1229 | if (mnt->mnt_ex_mountpoint.mnt) |
1230 | path_put(&mnt->mnt_ex_mountpoint); | |
d5e50f74 | 1231 | mntput(&mnt->mnt); |
70fbcdf4 RP |
1232 | } |
1233 | } | |
1234 | ||
97216be0 | 1235 | static inline void namespace_lock(void) |
e3197d83 | 1236 | { |
97216be0 | 1237 | down_write(&namespace_sem); |
e3197d83 AV |
1238 | } |
1239 | ||
99b7db7b | 1240 | /* |
48a066e7 | 1241 | * mount_lock must be held |
99b7db7b | 1242 | * namespace_sem must be held for write |
48a066e7 AV |
1243 | * how = 0 => just this tree, don't propagate |
1244 | * how = 1 => propagate; we know that nobody else has reference to any victims | |
1245 | * how = 2 => lazy umount | |
99b7db7b | 1246 | */ |
48a066e7 | 1247 | void umount_tree(struct mount *mnt, int how) |
1da177e4 | 1248 | { |
38129a13 | 1249 | HLIST_HEAD(tmp_list); |
315fc83e | 1250 | struct mount *p; |
38129a13 | 1251 | struct mount *last = NULL; |
1da177e4 | 1252 | |
38129a13 AV |
1253 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1254 | hlist_del_init_rcu(&p->mnt_hash); | |
1255 | hlist_add_head(&p->mnt_hash, &tmp_list); | |
1256 | } | |
1da177e4 | 1257 | |
48a066e7 | 1258 | if (how) |
7b8a53fd | 1259 | propagate_umount(&tmp_list); |
a05964f3 | 1260 | |
38129a13 | 1261 | hlist_for_each_entry(p, &tmp_list, mnt_hash) { |
6776db3d | 1262 | list_del_init(&p->mnt_expire); |
1a4eeaf2 | 1263 | list_del_init(&p->mnt_list); |
143c8c91 AV |
1264 | __touch_mnt_namespace(p->mnt_ns); |
1265 | p->mnt_ns = NULL; | |
48a066e7 AV |
1266 | if (how < 2) |
1267 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; | |
6b41d536 | 1268 | list_del_init(&p->mnt_child); |
676da58d | 1269 | if (mnt_has_parent(p)) { |
84d17192 | 1270 | put_mountpoint(p->mnt_mp); |
aba809cf AV |
1271 | /* move the reference to mountpoint into ->mnt_ex_mountpoint */ |
1272 | p->mnt_ex_mountpoint.dentry = p->mnt_mountpoint; | |
1273 | p->mnt_ex_mountpoint.mnt = &p->mnt_parent->mnt; | |
1274 | p->mnt_mountpoint = p->mnt.mnt_root; | |
1275 | p->mnt_parent = p; | |
84d17192 | 1276 | p->mnt_mp = NULL; |
7c4b93d8 | 1277 | } |
0f0afb1d | 1278 | change_mnt_propagation(p, MS_PRIVATE); |
38129a13 AV |
1279 | last = p; |
1280 | } | |
1281 | if (last) { | |
1282 | last->mnt_hash.next = unmounted.first; | |
1283 | unmounted.first = tmp_list.first; | |
1284 | unmounted.first->pprev = &unmounted.first; | |
1da177e4 LT |
1285 | } |
1286 | } | |
1287 | ||
b54b9be7 | 1288 | static void shrink_submounts(struct mount *mnt); |
c35038be | 1289 | |
1ab59738 | 1290 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1291 | { |
1ab59738 | 1292 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 LT |
1293 | int retval; |
1294 | ||
1ab59738 | 1295 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1296 | if (retval) |
1297 | return retval; | |
1298 | ||
1299 | /* | |
1300 | * Allow userspace to request a mountpoint be expired rather than | |
1301 | * unmounting unconditionally. Unmount only happens if: | |
1302 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1303 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1304 | */ | |
1305 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1306 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1307 | flags & (MNT_FORCE | MNT_DETACH)) |
1308 | return -EINVAL; | |
1309 | ||
b3e19d92 NP |
1310 | /* |
1311 | * probably don't strictly need the lock here if we examined | |
1312 | * all race cases, but it's a slowpath. | |
1313 | */ | |
719ea2fb | 1314 | lock_mount_hash(); |
83adc753 | 1315 | if (mnt_get_count(mnt) != 2) { |
719ea2fb | 1316 | unlock_mount_hash(); |
1da177e4 | 1317 | return -EBUSY; |
b3e19d92 | 1318 | } |
719ea2fb | 1319 | unlock_mount_hash(); |
1da177e4 | 1320 | |
863d684f | 1321 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
1da177e4 LT |
1322 | return -EAGAIN; |
1323 | } | |
1324 | ||
1325 | /* | |
1326 | * If we may have to abort operations to get out of this | |
1327 | * mount, and they will themselves hold resources we must | |
1328 | * allow the fs to do things. In the Unix tradition of | |
1329 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1330 | * might fail to complete on the first run through as other tasks | |
1331 | * must return, and the like. Thats for the mount program to worry | |
1332 | * about for the moment. | |
1333 | */ | |
1334 | ||
42faad99 | 1335 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1336 | sb->s_op->umount_begin(sb); |
42faad99 | 1337 | } |
1da177e4 LT |
1338 | |
1339 | /* | |
1340 | * No sense to grab the lock for this test, but test itself looks | |
1341 | * somewhat bogus. Suggestions for better replacement? | |
1342 | * Ho-hum... In principle, we might treat that as umount + switch | |
1343 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1344 | * Actually it makes sense, especially if rootfs would contain a | |
1345 | * /reboot - static binary that would close all descriptors and | |
1346 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1347 | */ | |
1ab59738 | 1348 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1349 | /* |
1350 | * Special case for "unmounting" root ... | |
1351 | * we just try to remount it readonly. | |
1352 | */ | |
1353 | down_write(&sb->s_umount); | |
4aa98cf7 | 1354 | if (!(sb->s_flags & MS_RDONLY)) |
1da177e4 | 1355 | retval = do_remount_sb(sb, MS_RDONLY, NULL, 0); |
1da177e4 LT |
1356 | up_write(&sb->s_umount); |
1357 | return retval; | |
1358 | } | |
1359 | ||
97216be0 | 1360 | namespace_lock(); |
719ea2fb | 1361 | lock_mount_hash(); |
5addc5dd | 1362 | event++; |
1da177e4 | 1363 | |
48a066e7 | 1364 | if (flags & MNT_DETACH) { |
1a4eeaf2 | 1365 | if (!list_empty(&mnt->mnt_list)) |
48a066e7 | 1366 | umount_tree(mnt, 2); |
1da177e4 | 1367 | retval = 0; |
48a066e7 AV |
1368 | } else { |
1369 | shrink_submounts(mnt); | |
1370 | retval = -EBUSY; | |
1371 | if (!propagate_mount_busy(mnt, 2)) { | |
1372 | if (!list_empty(&mnt->mnt_list)) | |
1373 | umount_tree(mnt, 1); | |
1374 | retval = 0; | |
1375 | } | |
1da177e4 | 1376 | } |
719ea2fb | 1377 | unlock_mount_hash(); |
e3197d83 | 1378 | namespace_unlock(); |
1da177e4 LT |
1379 | return retval; |
1380 | } | |
1381 | ||
9b40bc90 AV |
1382 | /* |
1383 | * Is the caller allowed to modify his namespace? | |
1384 | */ | |
1385 | static inline bool may_mount(void) | |
1386 | { | |
1387 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); | |
1388 | } | |
1389 | ||
1da177e4 LT |
1390 | /* |
1391 | * Now umount can handle mount points as well as block devices. | |
1392 | * This is important for filesystems which use unnamed block devices. | |
1393 | * | |
1394 | * We now support a flag for forced unmount like the other 'big iron' | |
1395 | * unixes. Our API is identical to OSF/1 to avoid making a mess of AMD | |
1396 | */ | |
1397 | ||
bdc480e3 | 1398 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1da177e4 | 1399 | { |
2d8f3038 | 1400 | struct path path; |
900148dc | 1401 | struct mount *mnt; |
1da177e4 | 1402 | int retval; |
db1f05bb | 1403 | int lookup_flags = 0; |
1da177e4 | 1404 | |
db1f05bb MS |
1405 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
1406 | return -EINVAL; | |
1407 | ||
9b40bc90 AV |
1408 | if (!may_mount()) |
1409 | return -EPERM; | |
1410 | ||
db1f05bb MS |
1411 | if (!(flags & UMOUNT_NOFOLLOW)) |
1412 | lookup_flags |= LOOKUP_FOLLOW; | |
1413 | ||
197df04c | 1414 | retval = user_path_mountpoint_at(AT_FDCWD, name, lookup_flags, &path); |
1da177e4 LT |
1415 | if (retval) |
1416 | goto out; | |
900148dc | 1417 | mnt = real_mount(path.mnt); |
1da177e4 | 1418 | retval = -EINVAL; |
2d8f3038 | 1419 | if (path.dentry != path.mnt->mnt_root) |
1da177e4 | 1420 | goto dput_and_out; |
143c8c91 | 1421 | if (!check_mnt(mnt)) |
1da177e4 | 1422 | goto dput_and_out; |
5ff9d8a6 EB |
1423 | if (mnt->mnt.mnt_flags & MNT_LOCKED) |
1424 | goto dput_and_out; | |
1da177e4 | 1425 | |
900148dc | 1426 | retval = do_umount(mnt, flags); |
1da177e4 | 1427 | dput_and_out: |
429731b1 | 1428 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
2d8f3038 | 1429 | dput(path.dentry); |
900148dc | 1430 | mntput_no_expire(mnt); |
1da177e4 LT |
1431 | out: |
1432 | return retval; | |
1433 | } | |
1434 | ||
1435 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT | |
1436 | ||
1437 | /* | |
b58fed8b | 1438 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1439 | */ |
bdc480e3 | 1440 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1441 | { |
b58fed8b | 1442 | return sys_umount(name, 0); |
1da177e4 LT |
1443 | } |
1444 | ||
1445 | #endif | |
1446 | ||
4ce5d2b1 | 1447 | static bool is_mnt_ns_file(struct dentry *dentry) |
8823c079 | 1448 | { |
4ce5d2b1 EB |
1449 | /* Is this a proxy for a mount namespace? */ |
1450 | struct inode *inode = dentry->d_inode; | |
0bb80f24 | 1451 | struct proc_ns *ei; |
8823c079 EB |
1452 | |
1453 | if (!proc_ns_inode(inode)) | |
1454 | return false; | |
1455 | ||
0bb80f24 | 1456 | ei = get_proc_ns(inode); |
8823c079 EB |
1457 | if (ei->ns_ops != &mntns_operations) |
1458 | return false; | |
1459 | ||
4ce5d2b1 EB |
1460 | return true; |
1461 | } | |
1462 | ||
1463 | static bool mnt_ns_loop(struct dentry *dentry) | |
1464 | { | |
1465 | /* Could bind mounting the mount namespace inode cause a | |
1466 | * mount namespace loop? | |
1467 | */ | |
1468 | struct mnt_namespace *mnt_ns; | |
1469 | if (!is_mnt_ns_file(dentry)) | |
1470 | return false; | |
1471 | ||
1472 | mnt_ns = get_proc_ns(dentry->d_inode)->ns; | |
8823c079 EB |
1473 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
1474 | } | |
1475 | ||
87129cc0 | 1476 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1477 | int flag) |
1da177e4 | 1478 | { |
84d17192 | 1479 | struct mount *res, *p, *q, *r, *parent; |
1da177e4 | 1480 | |
4ce5d2b1 EB |
1481 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
1482 | return ERR_PTR(-EINVAL); | |
1483 | ||
1484 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) | |
be34d1a3 | 1485 | return ERR_PTR(-EINVAL); |
9676f0c6 | 1486 | |
36341f64 | 1487 | res = q = clone_mnt(mnt, dentry, flag); |
be34d1a3 DH |
1488 | if (IS_ERR(q)) |
1489 | return q; | |
1490 | ||
5ff9d8a6 | 1491 | q->mnt.mnt_flags &= ~MNT_LOCKED; |
a73324da | 1492 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1493 | |
1494 | p = mnt; | |
6b41d536 | 1495 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1496 | struct mount *s; |
7ec02ef1 | 1497 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1498 | continue; |
1499 | ||
909b0a88 | 1500 | for (s = r; s; s = next_mnt(s, r)) { |
4ce5d2b1 EB |
1501 | if (!(flag & CL_COPY_UNBINDABLE) && |
1502 | IS_MNT_UNBINDABLE(s)) { | |
1503 | s = skip_mnt_tree(s); | |
1504 | continue; | |
1505 | } | |
1506 | if (!(flag & CL_COPY_MNT_NS_FILE) && | |
1507 | is_mnt_ns_file(s->mnt.mnt_root)) { | |
9676f0c6 RP |
1508 | s = skip_mnt_tree(s); |
1509 | continue; | |
1510 | } | |
0714a533 AV |
1511 | while (p != s->mnt_parent) { |
1512 | p = p->mnt_parent; | |
1513 | q = q->mnt_parent; | |
1da177e4 | 1514 | } |
87129cc0 | 1515 | p = s; |
84d17192 | 1516 | parent = q; |
87129cc0 | 1517 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
be34d1a3 DH |
1518 | if (IS_ERR(q)) |
1519 | goto out; | |
719ea2fb | 1520 | lock_mount_hash(); |
1a4eeaf2 | 1521 | list_add_tail(&q->mnt_list, &res->mnt_list); |
84d17192 | 1522 | attach_mnt(q, parent, p->mnt_mp); |
719ea2fb | 1523 | unlock_mount_hash(); |
1da177e4 LT |
1524 | } |
1525 | } | |
1526 | return res; | |
be34d1a3 | 1527 | out: |
1da177e4 | 1528 | if (res) { |
719ea2fb | 1529 | lock_mount_hash(); |
328e6d90 | 1530 | umount_tree(res, 0); |
719ea2fb | 1531 | unlock_mount_hash(); |
1da177e4 | 1532 | } |
be34d1a3 | 1533 | return q; |
1da177e4 LT |
1534 | } |
1535 | ||
be34d1a3 DH |
1536 | /* Caller should check returned pointer for errors */ |
1537 | ||
589ff870 | 1538 | struct vfsmount *collect_mounts(struct path *path) |
8aec0809 | 1539 | { |
cb338d06 | 1540 | struct mount *tree; |
97216be0 | 1541 | namespace_lock(); |
87129cc0 AV |
1542 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
1543 | CL_COPY_ALL | CL_PRIVATE); | |
328e6d90 | 1544 | namespace_unlock(); |
be34d1a3 | 1545 | if (IS_ERR(tree)) |
52e220d3 | 1546 | return ERR_CAST(tree); |
be34d1a3 | 1547 | return &tree->mnt; |
8aec0809 AV |
1548 | } |
1549 | ||
1550 | void drop_collected_mounts(struct vfsmount *mnt) | |
1551 | { | |
97216be0 | 1552 | namespace_lock(); |
719ea2fb | 1553 | lock_mount_hash(); |
328e6d90 | 1554 | umount_tree(real_mount(mnt), 0); |
719ea2fb | 1555 | unlock_mount_hash(); |
3ab6abee | 1556 | namespace_unlock(); |
8aec0809 AV |
1557 | } |
1558 | ||
1f707137 AV |
1559 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
1560 | struct vfsmount *root) | |
1561 | { | |
1a4eeaf2 | 1562 | struct mount *mnt; |
1f707137 AV |
1563 | int res = f(root, arg); |
1564 | if (res) | |
1565 | return res; | |
1a4eeaf2 AV |
1566 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
1567 | res = f(&mnt->mnt, arg); | |
1f707137 AV |
1568 | if (res) |
1569 | return res; | |
1570 | } | |
1571 | return 0; | |
1572 | } | |
1573 | ||
4b8b21f4 | 1574 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 1575 | { |
315fc83e | 1576 | struct mount *p; |
719f5d7f | 1577 | |
909b0a88 | 1578 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
fc7be130 | 1579 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
4b8b21f4 | 1580 | mnt_release_group_id(p); |
719f5d7f MS |
1581 | } |
1582 | } | |
1583 | ||
4b8b21f4 | 1584 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 1585 | { |
315fc83e | 1586 | struct mount *p; |
719f5d7f | 1587 | |
909b0a88 | 1588 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
fc7be130 | 1589 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
4b8b21f4 | 1590 | int err = mnt_alloc_group_id(p); |
719f5d7f | 1591 | if (err) { |
4b8b21f4 | 1592 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
1593 | return err; |
1594 | } | |
1595 | } | |
1596 | } | |
1597 | ||
1598 | return 0; | |
1599 | } | |
1600 | ||
b90fa9ae RP |
1601 | /* |
1602 | * @source_mnt : mount tree to be attached | |
21444403 RP |
1603 | * @nd : place the mount tree @source_mnt is attached |
1604 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
1605 | * store the parent mount and mountpoint dentry. | |
1606 | * (done when source_mnt is moved) | |
b90fa9ae RP |
1607 | * |
1608 | * NOTE: in the table below explains the semantics when a source mount | |
1609 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
1610 | * --------------------------------------------------------------------------- |
1611 | * | BIND MOUNT OPERATION | | |
1612 | * |************************************************************************** | |
1613 | * | source-->| shared | private | slave | unbindable | | |
1614 | * | dest | | | | | | |
1615 | * | | | | | | | | |
1616 | * | v | | | | | | |
1617 | * |************************************************************************** | |
1618 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
1619 | * | | | | | | | |
1620 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
1621 | * *************************************************************************** | |
b90fa9ae RP |
1622 | * A bind operation clones the source mount and mounts the clone on the |
1623 | * destination mount. | |
1624 | * | |
1625 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
1626 | * tree of the destination mount and the cloned mount is added to | |
1627 | * the peer group of the source mount. | |
1628 | * (+) the cloned mount is created under the destination mount and is marked | |
1629 | * as shared. The cloned mount is added to the peer group of the source | |
1630 | * mount. | |
5afe0022 RP |
1631 | * (+++) the mount is propagated to all the mounts in the propagation tree |
1632 | * of the destination mount and the cloned mount is made slave | |
1633 | * of the same master as that of the source mount. The cloned mount | |
1634 | * is marked as 'shared and slave'. | |
1635 | * (*) the cloned mount is made a slave of the same master as that of the | |
1636 | * source mount. | |
1637 | * | |
9676f0c6 RP |
1638 | * --------------------------------------------------------------------------- |
1639 | * | MOVE MOUNT OPERATION | | |
1640 | * |************************************************************************** | |
1641 | * | source-->| shared | private | slave | unbindable | | |
1642 | * | dest | | | | | | |
1643 | * | | | | | | | | |
1644 | * | v | | | | | | |
1645 | * |************************************************************************** | |
1646 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
1647 | * | | | | | | | |
1648 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
1649 | * *************************************************************************** | |
5afe0022 RP |
1650 | * |
1651 | * (+) the mount is moved to the destination. And is then propagated to | |
1652 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 1653 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
1654 | * (+++) the mount is moved to the destination and is then propagated to |
1655 | * all the mounts belonging to the destination mount's propagation tree. | |
1656 | * the mount is marked as 'shared and slave'. | |
1657 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
1658 | * |
1659 | * if the source mount is a tree, the operations explained above is | |
1660 | * applied to each mount in the tree. | |
1661 | * Must be called without spinlocks held, since this function can sleep | |
1662 | * in allocations. | |
1663 | */ | |
0fb54e50 | 1664 | static int attach_recursive_mnt(struct mount *source_mnt, |
84d17192 AV |
1665 | struct mount *dest_mnt, |
1666 | struct mountpoint *dest_mp, | |
1667 | struct path *parent_path) | |
b90fa9ae | 1668 | { |
38129a13 | 1669 | HLIST_HEAD(tree_list); |
315fc83e | 1670 | struct mount *child, *p; |
38129a13 | 1671 | struct hlist_node *n; |
719f5d7f | 1672 | int err; |
b90fa9ae | 1673 | |
fc7be130 | 1674 | if (IS_MNT_SHARED(dest_mnt)) { |
0fb54e50 | 1675 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
1676 | if (err) |
1677 | goto out; | |
0b1b901b | 1678 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
f2ebb3a9 | 1679 | lock_mount_hash(); |
0b1b901b AV |
1680 | if (err) |
1681 | goto out_cleanup_ids; | |
909b0a88 | 1682 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
0f0afb1d | 1683 | set_mnt_shared(p); |
0b1b901b AV |
1684 | } else { |
1685 | lock_mount_hash(); | |
b90fa9ae | 1686 | } |
1a390689 | 1687 | if (parent_path) { |
0fb54e50 | 1688 | detach_mnt(source_mnt, parent_path); |
84d17192 | 1689 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
143c8c91 | 1690 | touch_mnt_namespace(source_mnt->mnt_ns); |
21444403 | 1691 | } else { |
84d17192 | 1692 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
1d6a32ac | 1693 | commit_tree(source_mnt, NULL); |
21444403 | 1694 | } |
b90fa9ae | 1695 | |
38129a13 | 1696 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
1d6a32ac | 1697 | struct mount *q; |
38129a13 | 1698 | hlist_del_init(&child->mnt_hash); |
1d6a32ac AV |
1699 | q = __lookup_mnt_last(&child->mnt_parent->mnt, |
1700 | child->mnt_mountpoint); | |
1701 | commit_tree(child, q); | |
b90fa9ae | 1702 | } |
719ea2fb | 1703 | unlock_mount_hash(); |
99b7db7b | 1704 | |
b90fa9ae | 1705 | return 0; |
719f5d7f MS |
1706 | |
1707 | out_cleanup_ids: | |
f2ebb3a9 AV |
1708 | while (!hlist_empty(&tree_list)) { |
1709 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); | |
1710 | umount_tree(child, 0); | |
1711 | } | |
1712 | unlock_mount_hash(); | |
0b1b901b | 1713 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f MS |
1714 | out: |
1715 | return err; | |
b90fa9ae RP |
1716 | } |
1717 | ||
84d17192 | 1718 | static struct mountpoint *lock_mount(struct path *path) |
b12cea91 AV |
1719 | { |
1720 | struct vfsmount *mnt; | |
84d17192 | 1721 | struct dentry *dentry = path->dentry; |
b12cea91 | 1722 | retry: |
84d17192 AV |
1723 | mutex_lock(&dentry->d_inode->i_mutex); |
1724 | if (unlikely(cant_mount(dentry))) { | |
1725 | mutex_unlock(&dentry->d_inode->i_mutex); | |
1726 | return ERR_PTR(-ENOENT); | |
b12cea91 | 1727 | } |
97216be0 | 1728 | namespace_lock(); |
b12cea91 | 1729 | mnt = lookup_mnt(path); |
84d17192 AV |
1730 | if (likely(!mnt)) { |
1731 | struct mountpoint *mp = new_mountpoint(dentry); | |
1732 | if (IS_ERR(mp)) { | |
97216be0 | 1733 | namespace_unlock(); |
84d17192 AV |
1734 | mutex_unlock(&dentry->d_inode->i_mutex); |
1735 | return mp; | |
1736 | } | |
1737 | return mp; | |
1738 | } | |
97216be0 | 1739 | namespace_unlock(); |
b12cea91 AV |
1740 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
1741 | path_put(path); | |
1742 | path->mnt = mnt; | |
84d17192 | 1743 | dentry = path->dentry = dget(mnt->mnt_root); |
b12cea91 AV |
1744 | goto retry; |
1745 | } | |
1746 | ||
84d17192 | 1747 | static void unlock_mount(struct mountpoint *where) |
b12cea91 | 1748 | { |
84d17192 AV |
1749 | struct dentry *dentry = where->m_dentry; |
1750 | put_mountpoint(where); | |
328e6d90 | 1751 | namespace_unlock(); |
84d17192 | 1752 | mutex_unlock(&dentry->d_inode->i_mutex); |
b12cea91 AV |
1753 | } |
1754 | ||
84d17192 | 1755 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
1da177e4 | 1756 | { |
95bc5f25 | 1757 | if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER) |
1da177e4 LT |
1758 | return -EINVAL; |
1759 | ||
84d17192 | 1760 | if (S_ISDIR(mp->m_dentry->d_inode->i_mode) != |
95bc5f25 | 1761 | S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode)) |
1da177e4 LT |
1762 | return -ENOTDIR; |
1763 | ||
84d17192 | 1764 | return attach_recursive_mnt(mnt, p, mp, NULL); |
1da177e4 LT |
1765 | } |
1766 | ||
7a2e8a8f VA |
1767 | /* |
1768 | * Sanity check the flags to change_mnt_propagation. | |
1769 | */ | |
1770 | ||
1771 | static int flags_to_propagation_type(int flags) | |
1772 | { | |
7c6e984d | 1773 | int type = flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
1774 | |
1775 | /* Fail if any non-propagation flags are set */ | |
1776 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
1777 | return 0; | |
1778 | /* Only one propagation flag should be set */ | |
1779 | if (!is_power_of_2(type)) | |
1780 | return 0; | |
1781 | return type; | |
1782 | } | |
1783 | ||
07b20889 RP |
1784 | /* |
1785 | * recursively change the type of the mountpoint. | |
1786 | */ | |
0a0d8a46 | 1787 | static int do_change_type(struct path *path, int flag) |
07b20889 | 1788 | { |
315fc83e | 1789 | struct mount *m; |
4b8b21f4 | 1790 | struct mount *mnt = real_mount(path->mnt); |
07b20889 | 1791 | int recurse = flag & MS_REC; |
7a2e8a8f | 1792 | int type; |
719f5d7f | 1793 | int err = 0; |
07b20889 | 1794 | |
2d92ab3c | 1795 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
1796 | return -EINVAL; |
1797 | ||
7a2e8a8f VA |
1798 | type = flags_to_propagation_type(flag); |
1799 | if (!type) | |
1800 | return -EINVAL; | |
1801 | ||
97216be0 | 1802 | namespace_lock(); |
719f5d7f MS |
1803 | if (type == MS_SHARED) { |
1804 | err = invent_group_ids(mnt, recurse); | |
1805 | if (err) | |
1806 | goto out_unlock; | |
1807 | } | |
1808 | ||
719ea2fb | 1809 | lock_mount_hash(); |
909b0a88 | 1810 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
0f0afb1d | 1811 | change_mnt_propagation(m, type); |
719ea2fb | 1812 | unlock_mount_hash(); |
719f5d7f MS |
1813 | |
1814 | out_unlock: | |
97216be0 | 1815 | namespace_unlock(); |
719f5d7f | 1816 | return err; |
07b20889 RP |
1817 | } |
1818 | ||
5ff9d8a6 EB |
1819 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
1820 | { | |
1821 | struct mount *child; | |
1822 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
1823 | if (!is_subdir(child->mnt_mountpoint, dentry)) | |
1824 | continue; | |
1825 | ||
1826 | if (child->mnt.mnt_flags & MNT_LOCKED) | |
1827 | return true; | |
1828 | } | |
1829 | return false; | |
1830 | } | |
1831 | ||
1da177e4 LT |
1832 | /* |
1833 | * do loopback mount. | |
1834 | */ | |
808d4e3c | 1835 | static int do_loopback(struct path *path, const char *old_name, |
2dafe1c4 | 1836 | int recurse) |
1da177e4 | 1837 | { |
2d92ab3c | 1838 | struct path old_path; |
84d17192 AV |
1839 | struct mount *mnt = NULL, *old, *parent; |
1840 | struct mountpoint *mp; | |
57eccb83 | 1841 | int err; |
1da177e4 LT |
1842 | if (!old_name || !*old_name) |
1843 | return -EINVAL; | |
815d405c | 1844 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
1845 | if (err) |
1846 | return err; | |
1847 | ||
8823c079 | 1848 | err = -EINVAL; |
4ce5d2b1 | 1849 | if (mnt_ns_loop(old_path.dentry)) |
8823c079 EB |
1850 | goto out; |
1851 | ||
84d17192 AV |
1852 | mp = lock_mount(path); |
1853 | err = PTR_ERR(mp); | |
1854 | if (IS_ERR(mp)) | |
b12cea91 AV |
1855 | goto out; |
1856 | ||
87129cc0 | 1857 | old = real_mount(old_path.mnt); |
84d17192 | 1858 | parent = real_mount(path->mnt); |
87129cc0 | 1859 | |
1da177e4 | 1860 | err = -EINVAL; |
fc7be130 | 1861 | if (IS_MNT_UNBINDABLE(old)) |
b12cea91 | 1862 | goto out2; |
9676f0c6 | 1863 | |
84d17192 | 1864 | if (!check_mnt(parent) || !check_mnt(old)) |
b12cea91 | 1865 | goto out2; |
1da177e4 | 1866 | |
5ff9d8a6 EB |
1867 | if (!recurse && has_locked_children(old, old_path.dentry)) |
1868 | goto out2; | |
1869 | ||
ccd48bc7 | 1870 | if (recurse) |
4ce5d2b1 | 1871 | mnt = copy_tree(old, old_path.dentry, CL_COPY_MNT_NS_FILE); |
ccd48bc7 | 1872 | else |
87129cc0 | 1873 | mnt = clone_mnt(old, old_path.dentry, 0); |
ccd48bc7 | 1874 | |
be34d1a3 DH |
1875 | if (IS_ERR(mnt)) { |
1876 | err = PTR_ERR(mnt); | |
e9c5d8a5 | 1877 | goto out2; |
be34d1a3 | 1878 | } |
ccd48bc7 | 1879 | |
5ff9d8a6 EB |
1880 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
1881 | ||
84d17192 | 1882 | err = graft_tree(mnt, parent, mp); |
ccd48bc7 | 1883 | if (err) { |
719ea2fb | 1884 | lock_mount_hash(); |
328e6d90 | 1885 | umount_tree(mnt, 0); |
719ea2fb | 1886 | unlock_mount_hash(); |
5b83d2c5 | 1887 | } |
b12cea91 | 1888 | out2: |
84d17192 | 1889 | unlock_mount(mp); |
ccd48bc7 | 1890 | out: |
2d92ab3c | 1891 | path_put(&old_path); |
1da177e4 LT |
1892 | return err; |
1893 | } | |
1894 | ||
2e4b7fcd DH |
1895 | static int change_mount_flags(struct vfsmount *mnt, int ms_flags) |
1896 | { | |
1897 | int error = 0; | |
1898 | int readonly_request = 0; | |
1899 | ||
1900 | if (ms_flags & MS_RDONLY) | |
1901 | readonly_request = 1; | |
1902 | if (readonly_request == __mnt_is_readonly(mnt)) | |
1903 | return 0; | |
1904 | ||
90563b19 EB |
1905 | if (mnt->mnt_flags & MNT_LOCK_READONLY) |
1906 | return -EPERM; | |
1907 | ||
2e4b7fcd | 1908 | if (readonly_request) |
83adc753 | 1909 | error = mnt_make_readonly(real_mount(mnt)); |
2e4b7fcd | 1910 | else |
83adc753 | 1911 | __mnt_unmake_readonly(real_mount(mnt)); |
2e4b7fcd DH |
1912 | return error; |
1913 | } | |
1914 | ||
1da177e4 LT |
1915 | /* |
1916 | * change filesystem flags. dir should be a physical root of filesystem. | |
1917 | * If you've mounted a non-root directory somewhere and want to do remount | |
1918 | * on it - tough luck. | |
1919 | */ | |
0a0d8a46 | 1920 | static int do_remount(struct path *path, int flags, int mnt_flags, |
1da177e4 LT |
1921 | void *data) |
1922 | { | |
1923 | int err; | |
2d92ab3c | 1924 | struct super_block *sb = path->mnt->mnt_sb; |
143c8c91 | 1925 | struct mount *mnt = real_mount(path->mnt); |
1da177e4 | 1926 | |
143c8c91 | 1927 | if (!check_mnt(mnt)) |
1da177e4 LT |
1928 | return -EINVAL; |
1929 | ||
2d92ab3c | 1930 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
1931 | return -EINVAL; |
1932 | ||
ff36fe2c EP |
1933 | err = security_sb_remount(sb, data); |
1934 | if (err) | |
1935 | return err; | |
1936 | ||
1da177e4 | 1937 | down_write(&sb->s_umount); |
2e4b7fcd | 1938 | if (flags & MS_BIND) |
2d92ab3c | 1939 | err = change_mount_flags(path->mnt, flags); |
57eccb83 AV |
1940 | else if (!capable(CAP_SYS_ADMIN)) |
1941 | err = -EPERM; | |
4aa98cf7 | 1942 | else |
2e4b7fcd | 1943 | err = do_remount_sb(sb, flags, data, 0); |
7b43a79f | 1944 | if (!err) { |
719ea2fb | 1945 | lock_mount_hash(); |
143c8c91 AV |
1946 | mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK; |
1947 | mnt->mnt.mnt_flags = mnt_flags; | |
143c8c91 | 1948 | touch_mnt_namespace(mnt->mnt_ns); |
719ea2fb | 1949 | unlock_mount_hash(); |
0e55a7cc | 1950 | } |
6339dab8 | 1951 | up_write(&sb->s_umount); |
1da177e4 LT |
1952 | return err; |
1953 | } | |
1954 | ||
cbbe362c | 1955 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 1956 | { |
315fc83e | 1957 | struct mount *p; |
909b0a88 | 1958 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
fc7be130 | 1959 | if (IS_MNT_UNBINDABLE(p)) |
9676f0c6 RP |
1960 | return 1; |
1961 | } | |
1962 | return 0; | |
1963 | } | |
1964 | ||
808d4e3c | 1965 | static int do_move_mount(struct path *path, const char *old_name) |
1da177e4 | 1966 | { |
2d92ab3c | 1967 | struct path old_path, parent_path; |
676da58d | 1968 | struct mount *p; |
0fb54e50 | 1969 | struct mount *old; |
84d17192 | 1970 | struct mountpoint *mp; |
57eccb83 | 1971 | int err; |
1da177e4 LT |
1972 | if (!old_name || !*old_name) |
1973 | return -EINVAL; | |
2d92ab3c | 1974 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
1da177e4 LT |
1975 | if (err) |
1976 | return err; | |
1977 | ||
84d17192 AV |
1978 | mp = lock_mount(path); |
1979 | err = PTR_ERR(mp); | |
1980 | if (IS_ERR(mp)) | |
cc53ce53 DH |
1981 | goto out; |
1982 | ||
143c8c91 | 1983 | old = real_mount(old_path.mnt); |
fc7be130 | 1984 | p = real_mount(path->mnt); |
143c8c91 | 1985 | |
1da177e4 | 1986 | err = -EINVAL; |
fc7be130 | 1987 | if (!check_mnt(p) || !check_mnt(old)) |
1da177e4 LT |
1988 | goto out1; |
1989 | ||
5ff9d8a6 EB |
1990 | if (old->mnt.mnt_flags & MNT_LOCKED) |
1991 | goto out1; | |
1992 | ||
1da177e4 | 1993 | err = -EINVAL; |
2d92ab3c | 1994 | if (old_path.dentry != old_path.mnt->mnt_root) |
21444403 | 1995 | goto out1; |
1da177e4 | 1996 | |
676da58d | 1997 | if (!mnt_has_parent(old)) |
21444403 | 1998 | goto out1; |
1da177e4 | 1999 | |
2d92ab3c AV |
2000 | if (S_ISDIR(path->dentry->d_inode->i_mode) != |
2001 | S_ISDIR(old_path.dentry->d_inode->i_mode)) | |
21444403 RP |
2002 | goto out1; |
2003 | /* | |
2004 | * Don't move a mount residing in a shared parent. | |
2005 | */ | |
fc7be130 | 2006 | if (IS_MNT_SHARED(old->mnt_parent)) |
21444403 | 2007 | goto out1; |
9676f0c6 RP |
2008 | /* |
2009 | * Don't move a mount tree containing unbindable mounts to a destination | |
2010 | * mount which is shared. | |
2011 | */ | |
fc7be130 | 2012 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
9676f0c6 | 2013 | goto out1; |
1da177e4 | 2014 | err = -ELOOP; |
fc7be130 | 2015 | for (; mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 2016 | if (p == old) |
21444403 | 2017 | goto out1; |
1da177e4 | 2018 | |
84d17192 | 2019 | err = attach_recursive_mnt(old, real_mount(path->mnt), mp, &parent_path); |
4ac91378 | 2020 | if (err) |
21444403 | 2021 | goto out1; |
1da177e4 LT |
2022 | |
2023 | /* if the mount is moved, it should no longer be expire | |
2024 | * automatically */ | |
6776db3d | 2025 | list_del_init(&old->mnt_expire); |
1da177e4 | 2026 | out1: |
84d17192 | 2027 | unlock_mount(mp); |
1da177e4 | 2028 | out: |
1da177e4 | 2029 | if (!err) |
1a390689 | 2030 | path_put(&parent_path); |
2d92ab3c | 2031 | path_put(&old_path); |
1da177e4 LT |
2032 | return err; |
2033 | } | |
2034 | ||
9d412a43 AV |
2035 | static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) |
2036 | { | |
2037 | int err; | |
2038 | const char *subtype = strchr(fstype, '.'); | |
2039 | if (subtype) { | |
2040 | subtype++; | |
2041 | err = -EINVAL; | |
2042 | if (!subtype[0]) | |
2043 | goto err; | |
2044 | } else | |
2045 | subtype = ""; | |
2046 | ||
2047 | mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); | |
2048 | err = -ENOMEM; | |
2049 | if (!mnt->mnt_sb->s_subtype) | |
2050 | goto err; | |
2051 | return mnt; | |
2052 | ||
2053 | err: | |
2054 | mntput(mnt); | |
2055 | return ERR_PTR(err); | |
2056 | } | |
2057 | ||
9d412a43 AV |
2058 | /* |
2059 | * add a mount into a namespace's mount tree | |
2060 | */ | |
95bc5f25 | 2061 | static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) |
9d412a43 | 2062 | { |
84d17192 AV |
2063 | struct mountpoint *mp; |
2064 | struct mount *parent; | |
9d412a43 AV |
2065 | int err; |
2066 | ||
f2ebb3a9 | 2067 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
9d412a43 | 2068 | |
84d17192 AV |
2069 | mp = lock_mount(path); |
2070 | if (IS_ERR(mp)) | |
2071 | return PTR_ERR(mp); | |
9d412a43 | 2072 | |
84d17192 | 2073 | parent = real_mount(path->mnt); |
9d412a43 | 2074 | err = -EINVAL; |
84d17192 | 2075 | if (unlikely(!check_mnt(parent))) { |
156cacb1 AV |
2076 | /* that's acceptable only for automounts done in private ns */ |
2077 | if (!(mnt_flags & MNT_SHRINKABLE)) | |
2078 | goto unlock; | |
2079 | /* ... and for those we'd better have mountpoint still alive */ | |
84d17192 | 2080 | if (!parent->mnt_ns) |
156cacb1 AV |
2081 | goto unlock; |
2082 | } | |
9d412a43 AV |
2083 | |
2084 | /* Refuse the same filesystem on the same mount point */ | |
2085 | err = -EBUSY; | |
95bc5f25 | 2086 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 AV |
2087 | path->mnt->mnt_root == path->dentry) |
2088 | goto unlock; | |
2089 | ||
2090 | err = -EINVAL; | |
95bc5f25 | 2091 | if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode)) |
9d412a43 AV |
2092 | goto unlock; |
2093 | ||
95bc5f25 | 2094 | newmnt->mnt.mnt_flags = mnt_flags; |
84d17192 | 2095 | err = graft_tree(newmnt, parent, mp); |
9d412a43 AV |
2096 | |
2097 | unlock: | |
84d17192 | 2098 | unlock_mount(mp); |
9d412a43 AV |
2099 | return err; |
2100 | } | |
b1e75df4 | 2101 | |
1da177e4 LT |
2102 | /* |
2103 | * create a new mount for userspace and request it to be added into the | |
2104 | * namespace's tree | |
2105 | */ | |
0c55cfc4 | 2106 | static int do_new_mount(struct path *path, const char *fstype, int flags, |
808d4e3c | 2107 | int mnt_flags, const char *name, void *data) |
1da177e4 | 2108 | { |
0c55cfc4 | 2109 | struct file_system_type *type; |
9b40bc90 | 2110 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
1da177e4 | 2111 | struct vfsmount *mnt; |
15f9a3f3 | 2112 | int err; |
1da177e4 | 2113 | |
0c55cfc4 | 2114 | if (!fstype) |
1da177e4 LT |
2115 | return -EINVAL; |
2116 | ||
0c55cfc4 EB |
2117 | type = get_fs_type(fstype); |
2118 | if (!type) | |
2119 | return -ENODEV; | |
2120 | ||
2121 | if (user_ns != &init_user_ns) { | |
2122 | if (!(type->fs_flags & FS_USERNS_MOUNT)) { | |
2123 | put_filesystem(type); | |
2124 | return -EPERM; | |
2125 | } | |
2126 | /* Only in special cases allow devices from mounts | |
2127 | * created outside the initial user namespace. | |
2128 | */ | |
2129 | if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { | |
2130 | flags |= MS_NODEV; | |
2131 | mnt_flags |= MNT_NODEV; | |
2132 | } | |
2133 | } | |
2134 | ||
2135 | mnt = vfs_kern_mount(type, flags, name, data); | |
2136 | if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && | |
2137 | !mnt->mnt_sb->s_subtype) | |
2138 | mnt = fs_set_subtype(mnt, fstype); | |
2139 | ||
2140 | put_filesystem(type); | |
1da177e4 LT |
2141 | if (IS_ERR(mnt)) |
2142 | return PTR_ERR(mnt); | |
2143 | ||
95bc5f25 | 2144 | err = do_add_mount(real_mount(mnt), path, mnt_flags); |
15f9a3f3 AV |
2145 | if (err) |
2146 | mntput(mnt); | |
2147 | return err; | |
1da177e4 LT |
2148 | } |
2149 | ||
19a167af AV |
2150 | int finish_automount(struct vfsmount *m, struct path *path) |
2151 | { | |
6776db3d | 2152 | struct mount *mnt = real_mount(m); |
19a167af AV |
2153 | int err; |
2154 | /* The new mount record should have at least 2 refs to prevent it being | |
2155 | * expired before we get a chance to add it | |
2156 | */ | |
6776db3d | 2157 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
2158 | |
2159 | if (m->mnt_sb == path->mnt->mnt_sb && | |
2160 | m->mnt_root == path->dentry) { | |
b1e75df4 AV |
2161 | err = -ELOOP; |
2162 | goto fail; | |
19a167af AV |
2163 | } |
2164 | ||
95bc5f25 | 2165 | err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
b1e75df4 AV |
2166 | if (!err) |
2167 | return 0; | |
2168 | fail: | |
2169 | /* remove m from any expiration list it may be on */ | |
6776db3d | 2170 | if (!list_empty(&mnt->mnt_expire)) { |
97216be0 | 2171 | namespace_lock(); |
6776db3d | 2172 | list_del_init(&mnt->mnt_expire); |
97216be0 | 2173 | namespace_unlock(); |
19a167af | 2174 | } |
b1e75df4 AV |
2175 | mntput(m); |
2176 | mntput(m); | |
19a167af AV |
2177 | return err; |
2178 | } | |
2179 | ||
ea5b778a DH |
2180 | /** |
2181 | * mnt_set_expiry - Put a mount on an expiration list | |
2182 | * @mnt: The mount to list. | |
2183 | * @expiry_list: The list to add the mount to. | |
2184 | */ | |
2185 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
2186 | { | |
97216be0 | 2187 | namespace_lock(); |
ea5b778a | 2188 | |
6776db3d | 2189 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a | 2190 | |
97216be0 | 2191 | namespace_unlock(); |
ea5b778a DH |
2192 | } |
2193 | EXPORT_SYMBOL(mnt_set_expiry); | |
2194 | ||
1da177e4 LT |
2195 | /* |
2196 | * process a list of expirable mountpoints with the intent of discarding any | |
2197 | * mountpoints that aren't in use and haven't been touched since last we came | |
2198 | * here | |
2199 | */ | |
2200 | void mark_mounts_for_expiry(struct list_head *mounts) | |
2201 | { | |
761d5c38 | 2202 | struct mount *mnt, *next; |
1da177e4 LT |
2203 | LIST_HEAD(graveyard); |
2204 | ||
2205 | if (list_empty(mounts)) | |
2206 | return; | |
2207 | ||
97216be0 | 2208 | namespace_lock(); |
719ea2fb | 2209 | lock_mount_hash(); |
1da177e4 LT |
2210 | |
2211 | /* extract from the expiration list every vfsmount that matches the | |
2212 | * following criteria: | |
2213 | * - only referenced by its parent vfsmount | |
2214 | * - still marked for expiry (marked on the last call here; marks are | |
2215 | * cleared by mntput()) | |
2216 | */ | |
6776db3d | 2217 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
863d684f | 2218 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1ab59738 | 2219 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 2220 | continue; |
6776db3d | 2221 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 2222 | } |
bcc5c7d2 | 2223 | while (!list_empty(&graveyard)) { |
6776db3d | 2224 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
143c8c91 | 2225 | touch_mnt_namespace(mnt->mnt_ns); |
328e6d90 | 2226 | umount_tree(mnt, 1); |
bcc5c7d2 | 2227 | } |
719ea2fb | 2228 | unlock_mount_hash(); |
3ab6abee | 2229 | namespace_unlock(); |
5528f911 TM |
2230 | } |
2231 | ||
2232 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
2233 | ||
2234 | /* | |
2235 | * Ripoff of 'select_parent()' | |
2236 | * | |
2237 | * search the list of submounts for a given mountpoint, and move any | |
2238 | * shrinkable submounts to the 'graveyard' list. | |
2239 | */ | |
692afc31 | 2240 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 2241 | { |
692afc31 | 2242 | struct mount *this_parent = parent; |
5528f911 TM |
2243 | struct list_head *next; |
2244 | int found = 0; | |
2245 | ||
2246 | repeat: | |
6b41d536 | 2247 | next = this_parent->mnt_mounts.next; |
5528f911 | 2248 | resume: |
6b41d536 | 2249 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 2250 | struct list_head *tmp = next; |
6b41d536 | 2251 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
2252 | |
2253 | next = tmp->next; | |
692afc31 | 2254 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 2255 | continue; |
5528f911 TM |
2256 | /* |
2257 | * Descend a level if the d_mounts list is non-empty. | |
2258 | */ | |
6b41d536 | 2259 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
2260 | this_parent = mnt; |
2261 | goto repeat; | |
2262 | } | |
1da177e4 | 2263 | |
1ab59738 | 2264 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 2265 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
2266 | found++; |
2267 | } | |
1da177e4 | 2268 | } |
5528f911 TM |
2269 | /* |
2270 | * All done at this level ... ascend and resume the search | |
2271 | */ | |
2272 | if (this_parent != parent) { | |
6b41d536 | 2273 | next = this_parent->mnt_child.next; |
0714a533 | 2274 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
2275 | goto resume; |
2276 | } | |
2277 | return found; | |
2278 | } | |
2279 | ||
2280 | /* | |
2281 | * process a list of expirable mountpoints with the intent of discarding any | |
2282 | * submounts of a specific parent mountpoint | |
99b7db7b | 2283 | * |
48a066e7 | 2284 | * mount_lock must be held for write |
5528f911 | 2285 | */ |
b54b9be7 | 2286 | static void shrink_submounts(struct mount *mnt) |
5528f911 TM |
2287 | { |
2288 | LIST_HEAD(graveyard); | |
761d5c38 | 2289 | struct mount *m; |
5528f911 | 2290 | |
5528f911 | 2291 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 2292 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 2293 | while (!list_empty(&graveyard)) { |
761d5c38 | 2294 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 2295 | mnt_expire); |
143c8c91 | 2296 | touch_mnt_namespace(m->mnt_ns); |
328e6d90 | 2297 | umount_tree(m, 1); |
bcc5c7d2 AV |
2298 | } |
2299 | } | |
1da177e4 LT |
2300 | } |
2301 | ||
1da177e4 LT |
2302 | /* |
2303 | * Some copy_from_user() implementations do not return the exact number of | |
2304 | * bytes remaining to copy on a fault. But copy_mount_options() requires that. | |
2305 | * Note that this function differs from copy_from_user() in that it will oops | |
2306 | * on bad values of `to', rather than returning a short copy. | |
2307 | */ | |
b58fed8b RP |
2308 | static long exact_copy_from_user(void *to, const void __user * from, |
2309 | unsigned long n) | |
1da177e4 LT |
2310 | { |
2311 | char *t = to; | |
2312 | const char __user *f = from; | |
2313 | char c; | |
2314 | ||
2315 | if (!access_ok(VERIFY_READ, from, n)) | |
2316 | return n; | |
2317 | ||
2318 | while (n) { | |
2319 | if (__get_user(c, f)) { | |
2320 | memset(t, 0, n); | |
2321 | break; | |
2322 | } | |
2323 | *t++ = c; | |
2324 | f++; | |
2325 | n--; | |
2326 | } | |
2327 | return n; | |
2328 | } | |
2329 | ||
b58fed8b | 2330 | int copy_mount_options(const void __user * data, unsigned long *where) |
1da177e4 LT |
2331 | { |
2332 | int i; | |
2333 | unsigned long page; | |
2334 | unsigned long size; | |
b58fed8b | 2335 | |
1da177e4 LT |
2336 | *where = 0; |
2337 | if (!data) | |
2338 | return 0; | |
2339 | ||
2340 | if (!(page = __get_free_page(GFP_KERNEL))) | |
2341 | return -ENOMEM; | |
2342 | ||
2343 | /* We only care that *some* data at the address the user | |
2344 | * gave us is valid. Just in case, we'll zero | |
2345 | * the remainder of the page. | |
2346 | */ | |
2347 | /* copy_from_user cannot cross TASK_SIZE ! */ | |
2348 | size = TASK_SIZE - (unsigned long)data; | |
2349 | if (size > PAGE_SIZE) | |
2350 | size = PAGE_SIZE; | |
2351 | ||
2352 | i = size - exact_copy_from_user((void *)page, data, size); | |
2353 | if (!i) { | |
b58fed8b | 2354 | free_page(page); |
1da177e4 LT |
2355 | return -EFAULT; |
2356 | } | |
2357 | if (i != PAGE_SIZE) | |
2358 | memset((char *)page + i, 0, PAGE_SIZE - i); | |
2359 | *where = page; | |
2360 | return 0; | |
2361 | } | |
2362 | ||
eca6f534 VN |
2363 | int copy_mount_string(const void __user *data, char **where) |
2364 | { | |
2365 | char *tmp; | |
2366 | ||
2367 | if (!data) { | |
2368 | *where = NULL; | |
2369 | return 0; | |
2370 | } | |
2371 | ||
2372 | tmp = strndup_user(data, PAGE_SIZE); | |
2373 | if (IS_ERR(tmp)) | |
2374 | return PTR_ERR(tmp); | |
2375 | ||
2376 | *where = tmp; | |
2377 | return 0; | |
2378 | } | |
2379 | ||
1da177e4 LT |
2380 | /* |
2381 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
2382 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
2383 | * | |
2384 | * data is a (void *) that can point to any structure up to | |
2385 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
2386 | * information (or be NULL). | |
2387 | * | |
2388 | * Pre-0.97 versions of mount() didn't have a flags word. | |
2389 | * When the flags word was introduced its top half was required | |
2390 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
2391 | * Therefore, if this magic number is present, it carries no information | |
2392 | * and must be discarded. | |
2393 | */ | |
808d4e3c AV |
2394 | long do_mount(const char *dev_name, const char *dir_name, |
2395 | const char *type_page, unsigned long flags, void *data_page) | |
1da177e4 | 2396 | { |
2d92ab3c | 2397 | struct path path; |
1da177e4 LT |
2398 | int retval = 0; |
2399 | int mnt_flags = 0; | |
2400 | ||
2401 | /* Discard magic */ | |
2402 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
2403 | flags &= ~MS_MGC_MSK; | |
2404 | ||
2405 | /* Basic sanity checks */ | |
2406 | ||
2407 | if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE)) | |
2408 | return -EINVAL; | |
1da177e4 LT |
2409 | |
2410 | if (data_page) | |
2411 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
2412 | ||
a27ab9f2 TH |
2413 | /* ... and get the mountpoint */ |
2414 | retval = kern_path(dir_name, LOOKUP_FOLLOW, &path); | |
2415 | if (retval) | |
2416 | return retval; | |
2417 | ||
2418 | retval = security_sb_mount(dev_name, &path, | |
2419 | type_page, flags, data_page); | |
0d5cadb8 AV |
2420 | if (!retval && !may_mount()) |
2421 | retval = -EPERM; | |
a27ab9f2 TH |
2422 | if (retval) |
2423 | goto dput_out; | |
2424 | ||
613cbe3d AK |
2425 | /* Default to relatime unless overriden */ |
2426 | if (!(flags & MS_NOATIME)) | |
2427 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 2428 | |
1da177e4 LT |
2429 | /* Separate the per-mountpoint flags */ |
2430 | if (flags & MS_NOSUID) | |
2431 | mnt_flags |= MNT_NOSUID; | |
2432 | if (flags & MS_NODEV) | |
2433 | mnt_flags |= MNT_NODEV; | |
2434 | if (flags & MS_NOEXEC) | |
2435 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
2436 | if (flags & MS_NOATIME) |
2437 | mnt_flags |= MNT_NOATIME; | |
2438 | if (flags & MS_NODIRATIME) | |
2439 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
2440 | if (flags & MS_STRICTATIME) |
2441 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
2e4b7fcd DH |
2442 | if (flags & MS_RDONLY) |
2443 | mnt_flags |= MNT_READONLY; | |
fc33a7bb | 2444 | |
7a4dec53 | 2445 | flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | |
d0adde57 MG |
2446 | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | |
2447 | MS_STRICTATIME); | |
1da177e4 | 2448 | |
1da177e4 | 2449 | if (flags & MS_REMOUNT) |
2d92ab3c | 2450 | retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags, |
1da177e4 LT |
2451 | data_page); |
2452 | else if (flags & MS_BIND) | |
2d92ab3c | 2453 | retval = do_loopback(&path, dev_name, flags & MS_REC); |
9676f0c6 | 2454 | else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
2d92ab3c | 2455 | retval = do_change_type(&path, flags); |
1da177e4 | 2456 | else if (flags & MS_MOVE) |
2d92ab3c | 2457 | retval = do_move_mount(&path, dev_name); |
1da177e4 | 2458 | else |
2d92ab3c | 2459 | retval = do_new_mount(&path, type_page, flags, mnt_flags, |
1da177e4 LT |
2460 | dev_name, data_page); |
2461 | dput_out: | |
2d92ab3c | 2462 | path_put(&path); |
1da177e4 LT |
2463 | return retval; |
2464 | } | |
2465 | ||
771b1371 EB |
2466 | static void free_mnt_ns(struct mnt_namespace *ns) |
2467 | { | |
98f842e6 | 2468 | proc_free_inum(ns->proc_inum); |
771b1371 EB |
2469 | put_user_ns(ns->user_ns); |
2470 | kfree(ns); | |
2471 | } | |
2472 | ||
8823c079 EB |
2473 | /* |
2474 | * Assign a sequence number so we can detect when we attempt to bind | |
2475 | * mount a reference to an older mount namespace into the current | |
2476 | * mount namespace, preventing reference counting loops. A 64bit | |
2477 | * number incrementing at 10Ghz will take 12,427 years to wrap which | |
2478 | * is effectively never, so we can ignore the possibility. | |
2479 | */ | |
2480 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); | |
2481 | ||
771b1371 | 2482 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) |
cf8d2c11 TM |
2483 | { |
2484 | struct mnt_namespace *new_ns; | |
98f842e6 | 2485 | int ret; |
cf8d2c11 TM |
2486 | |
2487 | new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL); | |
2488 | if (!new_ns) | |
2489 | return ERR_PTR(-ENOMEM); | |
98f842e6 EB |
2490 | ret = proc_alloc_inum(&new_ns->proc_inum); |
2491 | if (ret) { | |
2492 | kfree(new_ns); | |
2493 | return ERR_PTR(ret); | |
2494 | } | |
8823c079 | 2495 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
cf8d2c11 TM |
2496 | atomic_set(&new_ns->count, 1); |
2497 | new_ns->root = NULL; | |
2498 | INIT_LIST_HEAD(&new_ns->list); | |
2499 | init_waitqueue_head(&new_ns->poll); | |
2500 | new_ns->event = 0; | |
771b1371 | 2501 | new_ns->user_ns = get_user_ns(user_ns); |
cf8d2c11 TM |
2502 | return new_ns; |
2503 | } | |
2504 | ||
9559f689 AV |
2505 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
2506 | struct user_namespace *user_ns, struct fs_struct *new_fs) | |
1da177e4 | 2507 | { |
6b3286ed | 2508 | struct mnt_namespace *new_ns; |
7f2da1e7 | 2509 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 2510 | struct mount *p, *q; |
9559f689 | 2511 | struct mount *old; |
cb338d06 | 2512 | struct mount *new; |
7a472ef4 | 2513 | int copy_flags; |
1da177e4 | 2514 | |
9559f689 AV |
2515 | BUG_ON(!ns); |
2516 | ||
2517 | if (likely(!(flags & CLONE_NEWNS))) { | |
2518 | get_mnt_ns(ns); | |
2519 | return ns; | |
2520 | } | |
2521 | ||
2522 | old = ns->root; | |
2523 | ||
771b1371 | 2524 | new_ns = alloc_mnt_ns(user_ns); |
cf8d2c11 TM |
2525 | if (IS_ERR(new_ns)) |
2526 | return new_ns; | |
1da177e4 | 2527 | |
97216be0 | 2528 | namespace_lock(); |
1da177e4 | 2529 | /* First pass: copy the tree topology */ |
4ce5d2b1 | 2530 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
9559f689 | 2531 | if (user_ns != ns->user_ns) |
132c94e3 | 2532 | copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED; |
7a472ef4 | 2533 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
be34d1a3 | 2534 | if (IS_ERR(new)) { |
328e6d90 | 2535 | namespace_unlock(); |
771b1371 | 2536 | free_mnt_ns(new_ns); |
be34d1a3 | 2537 | return ERR_CAST(new); |
1da177e4 | 2538 | } |
be08d6d2 | 2539 | new_ns->root = new; |
1a4eeaf2 | 2540 | list_add_tail(&new_ns->list, &new->mnt_list); |
1da177e4 LT |
2541 | |
2542 | /* | |
2543 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
2544 | * as belonging to new namespace. We have already acquired a private | |
2545 | * fs_struct, so tsk->fs->lock is not needed. | |
2546 | */ | |
909b0a88 | 2547 | p = old; |
cb338d06 | 2548 | q = new; |
1da177e4 | 2549 | while (p) { |
143c8c91 | 2550 | q->mnt_ns = new_ns; |
9559f689 AV |
2551 | if (new_fs) { |
2552 | if (&p->mnt == new_fs->root.mnt) { | |
2553 | new_fs->root.mnt = mntget(&q->mnt); | |
315fc83e | 2554 | rootmnt = &p->mnt; |
1da177e4 | 2555 | } |
9559f689 AV |
2556 | if (&p->mnt == new_fs->pwd.mnt) { |
2557 | new_fs->pwd.mnt = mntget(&q->mnt); | |
315fc83e | 2558 | pwdmnt = &p->mnt; |
1da177e4 | 2559 | } |
1da177e4 | 2560 | } |
909b0a88 AV |
2561 | p = next_mnt(p, old); |
2562 | q = next_mnt(q, new); | |
4ce5d2b1 EB |
2563 | if (!q) |
2564 | break; | |
2565 | while (p->mnt.mnt_root != q->mnt.mnt_root) | |
2566 | p = next_mnt(p, old); | |
1da177e4 | 2567 | } |
328e6d90 | 2568 | namespace_unlock(); |
1da177e4 | 2569 | |
1da177e4 | 2570 | if (rootmnt) |
f03c6599 | 2571 | mntput(rootmnt); |
1da177e4 | 2572 | if (pwdmnt) |
f03c6599 | 2573 | mntput(pwdmnt); |
1da177e4 | 2574 | |
741a2951 | 2575 | return new_ns; |
1da177e4 LT |
2576 | } |
2577 | ||
cf8d2c11 TM |
2578 | /** |
2579 | * create_mnt_ns - creates a private namespace and adds a root filesystem | |
2580 | * @mnt: pointer to the new root filesystem mountpoint | |
2581 | */ | |
1a4eeaf2 | 2582 | static struct mnt_namespace *create_mnt_ns(struct vfsmount *m) |
cf8d2c11 | 2583 | { |
771b1371 | 2584 | struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns); |
cf8d2c11 | 2585 | if (!IS_ERR(new_ns)) { |
1a4eeaf2 AV |
2586 | struct mount *mnt = real_mount(m); |
2587 | mnt->mnt_ns = new_ns; | |
be08d6d2 | 2588 | new_ns->root = mnt; |
b1983cd8 | 2589 | list_add(&mnt->mnt_list, &new_ns->list); |
c1334495 | 2590 | } else { |
1a4eeaf2 | 2591 | mntput(m); |
cf8d2c11 TM |
2592 | } |
2593 | return new_ns; | |
2594 | } | |
cf8d2c11 | 2595 | |
ea441d11 AV |
2596 | struct dentry *mount_subtree(struct vfsmount *mnt, const char *name) |
2597 | { | |
2598 | struct mnt_namespace *ns; | |
d31da0f0 | 2599 | struct super_block *s; |
ea441d11 AV |
2600 | struct path path; |
2601 | int err; | |
2602 | ||
2603 | ns = create_mnt_ns(mnt); | |
2604 | if (IS_ERR(ns)) | |
2605 | return ERR_CAST(ns); | |
2606 | ||
2607 | err = vfs_path_lookup(mnt->mnt_root, mnt, | |
2608 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); | |
2609 | ||
2610 | put_mnt_ns(ns); | |
2611 | ||
2612 | if (err) | |
2613 | return ERR_PTR(err); | |
2614 | ||
2615 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
2616 | s = path.mnt->mnt_sb; |
2617 | atomic_inc(&s->s_active); | |
ea441d11 AV |
2618 | mntput(path.mnt); |
2619 | /* lock the sucker */ | |
d31da0f0 | 2620 | down_write(&s->s_umount); |
ea441d11 AV |
2621 | /* ... and return the root of (sub)tree on it */ |
2622 | return path.dentry; | |
2623 | } | |
2624 | EXPORT_SYMBOL(mount_subtree); | |
2625 | ||
bdc480e3 HC |
2626 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
2627 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 2628 | { |
eca6f534 VN |
2629 | int ret; |
2630 | char *kernel_type; | |
91a27b2a | 2631 | struct filename *kernel_dir; |
eca6f534 | 2632 | char *kernel_dev; |
1da177e4 | 2633 | unsigned long data_page; |
1da177e4 | 2634 | |
eca6f534 VN |
2635 | ret = copy_mount_string(type, &kernel_type); |
2636 | if (ret < 0) | |
2637 | goto out_type; | |
1da177e4 | 2638 | |
eca6f534 VN |
2639 | kernel_dir = getname(dir_name); |
2640 | if (IS_ERR(kernel_dir)) { | |
2641 | ret = PTR_ERR(kernel_dir); | |
2642 | goto out_dir; | |
2643 | } | |
1da177e4 | 2644 | |
eca6f534 VN |
2645 | ret = copy_mount_string(dev_name, &kernel_dev); |
2646 | if (ret < 0) | |
2647 | goto out_dev; | |
1da177e4 | 2648 | |
eca6f534 VN |
2649 | ret = copy_mount_options(data, &data_page); |
2650 | if (ret < 0) | |
2651 | goto out_data; | |
1da177e4 | 2652 | |
91a27b2a | 2653 | ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags, |
eca6f534 | 2654 | (void *) data_page); |
1da177e4 | 2655 | |
eca6f534 VN |
2656 | free_page(data_page); |
2657 | out_data: | |
2658 | kfree(kernel_dev); | |
2659 | out_dev: | |
2660 | putname(kernel_dir); | |
2661 | out_dir: | |
2662 | kfree(kernel_type); | |
2663 | out_type: | |
2664 | return ret; | |
1da177e4 LT |
2665 | } |
2666 | ||
afac7cba AV |
2667 | /* |
2668 | * Return true if path is reachable from root | |
2669 | * | |
48a066e7 | 2670 | * namespace_sem or mount_lock is held |
afac7cba | 2671 | */ |
643822b4 | 2672 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
2673 | const struct path *root) |
2674 | { | |
643822b4 | 2675 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 2676 | dentry = mnt->mnt_mountpoint; |
0714a533 | 2677 | mnt = mnt->mnt_parent; |
afac7cba | 2678 | } |
643822b4 | 2679 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
2680 | } |
2681 | ||
2682 | int path_is_under(struct path *path1, struct path *path2) | |
2683 | { | |
2684 | int res; | |
48a066e7 | 2685 | read_seqlock_excl(&mount_lock); |
643822b4 | 2686 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
48a066e7 | 2687 | read_sequnlock_excl(&mount_lock); |
afac7cba AV |
2688 | return res; |
2689 | } | |
2690 | EXPORT_SYMBOL(path_is_under); | |
2691 | ||
1da177e4 LT |
2692 | /* |
2693 | * pivot_root Semantics: | |
2694 | * Moves the root file system of the current process to the directory put_old, | |
2695 | * makes new_root as the new root file system of the current process, and sets | |
2696 | * root/cwd of all processes which had them on the current root to new_root. | |
2697 | * | |
2698 | * Restrictions: | |
2699 | * The new_root and put_old must be directories, and must not be on the | |
2700 | * same file system as the current process root. The put_old must be | |
2701 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
2702 | * pointed to by put_old must yield the same directory as new_root. No other | |
2703 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
2704 | * | |
4a0d11fa NB |
2705 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
2706 | * See Documentation/filesystems/ramfs-rootfs-initramfs.txt for alternatives | |
2707 | * in this situation. | |
2708 | * | |
1da177e4 LT |
2709 | * Notes: |
2710 | * - we don't move root/cwd if they are not at the root (reason: if something | |
2711 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
2712 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
2713 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
2714 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
2715 | * first. | |
2716 | */ | |
3480b257 HC |
2717 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
2718 | const char __user *, put_old) | |
1da177e4 | 2719 | { |
2d8f3038 | 2720 | struct path new, old, parent_path, root_parent, root; |
84d17192 AV |
2721 | struct mount *new_mnt, *root_mnt, *old_mnt; |
2722 | struct mountpoint *old_mp, *root_mp; | |
1da177e4 LT |
2723 | int error; |
2724 | ||
9b40bc90 | 2725 | if (!may_mount()) |
1da177e4 LT |
2726 | return -EPERM; |
2727 | ||
2d8f3038 | 2728 | error = user_path_dir(new_root, &new); |
1da177e4 LT |
2729 | if (error) |
2730 | goto out0; | |
1da177e4 | 2731 | |
2d8f3038 | 2732 | error = user_path_dir(put_old, &old); |
1da177e4 LT |
2733 | if (error) |
2734 | goto out1; | |
2735 | ||
2d8f3038 | 2736 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
2737 | if (error) |
2738 | goto out2; | |
1da177e4 | 2739 | |
f7ad3c6b | 2740 | get_fs_root(current->fs, &root); |
84d17192 AV |
2741 | old_mp = lock_mount(&old); |
2742 | error = PTR_ERR(old_mp); | |
2743 | if (IS_ERR(old_mp)) | |
b12cea91 AV |
2744 | goto out3; |
2745 | ||
1da177e4 | 2746 | error = -EINVAL; |
419148da AV |
2747 | new_mnt = real_mount(new.mnt); |
2748 | root_mnt = real_mount(root.mnt); | |
84d17192 AV |
2749 | old_mnt = real_mount(old.mnt); |
2750 | if (IS_MNT_SHARED(old_mnt) || | |
fc7be130 AV |
2751 | IS_MNT_SHARED(new_mnt->mnt_parent) || |
2752 | IS_MNT_SHARED(root_mnt->mnt_parent)) | |
b12cea91 | 2753 | goto out4; |
143c8c91 | 2754 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
b12cea91 | 2755 | goto out4; |
5ff9d8a6 EB |
2756 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
2757 | goto out4; | |
1da177e4 | 2758 | error = -ENOENT; |
f3da392e | 2759 | if (d_unlinked(new.dentry)) |
b12cea91 | 2760 | goto out4; |
1da177e4 | 2761 | error = -EBUSY; |
84d17192 | 2762 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
b12cea91 | 2763 | goto out4; /* loop, on the same file system */ |
1da177e4 | 2764 | error = -EINVAL; |
8c3ee42e | 2765 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 2766 | goto out4; /* not a mountpoint */ |
676da58d | 2767 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 2768 | goto out4; /* not attached */ |
84d17192 | 2769 | root_mp = root_mnt->mnt_mp; |
2d8f3038 | 2770 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 2771 | goto out4; /* not a mountpoint */ |
676da58d | 2772 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 2773 | goto out4; /* not attached */ |
4ac91378 | 2774 | /* make sure we can reach put_old from new_root */ |
84d17192 | 2775 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
b12cea91 | 2776 | goto out4; |
84d17192 | 2777 | root_mp->m_count++; /* pin it so it won't go away */ |
719ea2fb | 2778 | lock_mount_hash(); |
419148da AV |
2779 | detach_mnt(new_mnt, &parent_path); |
2780 | detach_mnt(root_mnt, &root_parent); | |
5ff9d8a6 EB |
2781 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
2782 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; | |
2783 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
2784 | } | |
4ac91378 | 2785 | /* mount old root on put_old */ |
84d17192 | 2786 | attach_mnt(root_mnt, old_mnt, old_mp); |
4ac91378 | 2787 | /* mount new_root on / */ |
84d17192 | 2788 | attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp); |
6b3286ed | 2789 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
719ea2fb | 2790 | unlock_mount_hash(); |
2d8f3038 | 2791 | chroot_fs_refs(&root, &new); |
84d17192 | 2792 | put_mountpoint(root_mp); |
1da177e4 | 2793 | error = 0; |
b12cea91 | 2794 | out4: |
84d17192 | 2795 | unlock_mount(old_mp); |
b12cea91 AV |
2796 | if (!error) { |
2797 | path_put(&root_parent); | |
2798 | path_put(&parent_path); | |
2799 | } | |
2800 | out3: | |
8c3ee42e | 2801 | path_put(&root); |
b12cea91 | 2802 | out2: |
2d8f3038 | 2803 | path_put(&old); |
1da177e4 | 2804 | out1: |
2d8f3038 | 2805 | path_put(&new); |
1da177e4 | 2806 | out0: |
1da177e4 | 2807 | return error; |
1da177e4 LT |
2808 | } |
2809 | ||
2810 | static void __init init_mount_tree(void) | |
2811 | { | |
2812 | struct vfsmount *mnt; | |
6b3286ed | 2813 | struct mnt_namespace *ns; |
ac748a09 | 2814 | struct path root; |
0c55cfc4 | 2815 | struct file_system_type *type; |
1da177e4 | 2816 | |
0c55cfc4 EB |
2817 | type = get_fs_type("rootfs"); |
2818 | if (!type) | |
2819 | panic("Can't find rootfs type"); | |
2820 | mnt = vfs_kern_mount(type, 0, "rootfs", NULL); | |
2821 | put_filesystem(type); | |
1da177e4 LT |
2822 | if (IS_ERR(mnt)) |
2823 | panic("Can't create rootfs"); | |
b3e19d92 | 2824 | |
3b22edc5 TM |
2825 | ns = create_mnt_ns(mnt); |
2826 | if (IS_ERR(ns)) | |
1da177e4 | 2827 | panic("Can't allocate initial namespace"); |
6b3286ed KK |
2828 | |
2829 | init_task.nsproxy->mnt_ns = ns; | |
2830 | get_mnt_ns(ns); | |
2831 | ||
be08d6d2 AV |
2832 | root.mnt = mnt; |
2833 | root.dentry = mnt->mnt_root; | |
ac748a09 JB |
2834 | |
2835 | set_fs_pwd(current->fs, &root); | |
2836 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
2837 | } |
2838 | ||
74bf17cf | 2839 | void __init mnt_init(void) |
1da177e4 | 2840 | { |
13f14b4d | 2841 | unsigned u; |
15a67dd8 | 2842 | int err; |
1da177e4 | 2843 | |
7d6fec45 | 2844 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
20c2df83 | 2845 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
1da177e4 | 2846 | |
0818bf27 | 2847 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
38129a13 | 2848 | sizeof(struct hlist_head), |
0818bf27 AV |
2849 | mhash_entries, 19, |
2850 | 0, | |
2851 | &m_hash_shift, &m_hash_mask, 0, 0); | |
2852 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", | |
2853 | sizeof(struct hlist_head), | |
2854 | mphash_entries, 19, | |
2855 | 0, | |
2856 | &mp_hash_shift, &mp_hash_mask, 0, 0); | |
1da177e4 | 2857 | |
84d17192 | 2858 | if (!mount_hashtable || !mountpoint_hashtable) |
1da177e4 LT |
2859 | panic("Failed to allocate mount hash table\n"); |
2860 | ||
0818bf27 | 2861 | for (u = 0; u <= m_hash_mask; u++) |
38129a13 | 2862 | INIT_HLIST_HEAD(&mount_hashtable[u]); |
0818bf27 AV |
2863 | for (u = 0; u <= mp_hash_mask; u++) |
2864 | INIT_HLIST_HEAD(&mountpoint_hashtable[u]); | |
1da177e4 | 2865 | |
4b93dc9b TH |
2866 | kernfs_init(); |
2867 | ||
15a67dd8 RD |
2868 | err = sysfs_init(); |
2869 | if (err) | |
2870 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 2871 | __func__, err); |
00d26666 GKH |
2872 | fs_kobj = kobject_create_and_add("fs", NULL); |
2873 | if (!fs_kobj) | |
8e24eea7 | 2874 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
1da177e4 LT |
2875 | init_rootfs(); |
2876 | init_mount_tree(); | |
2877 | } | |
2878 | ||
616511d0 | 2879 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 2880 | { |
d498b25a | 2881 | if (!atomic_dec_and_test(&ns->count)) |
616511d0 | 2882 | return; |
7b00ed6f | 2883 | drop_collected_mounts(&ns->root->mnt); |
771b1371 | 2884 | free_mnt_ns(ns); |
1da177e4 | 2885 | } |
9d412a43 AV |
2886 | |
2887 | struct vfsmount *kern_mount_data(struct file_system_type *type, void *data) | |
2888 | { | |
423e0ab0 TC |
2889 | struct vfsmount *mnt; |
2890 | mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data); | |
2891 | if (!IS_ERR(mnt)) { | |
2892 | /* | |
2893 | * it is a longterm mount, don't release mnt until | |
2894 | * we unmount before file sys is unregistered | |
2895 | */ | |
f7a99c5b | 2896 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
423e0ab0 TC |
2897 | } |
2898 | return mnt; | |
9d412a43 AV |
2899 | } |
2900 | EXPORT_SYMBOL_GPL(kern_mount_data); | |
423e0ab0 TC |
2901 | |
2902 | void kern_unmount(struct vfsmount *mnt) | |
2903 | { | |
2904 | /* release long term mount so mount point can be released */ | |
2905 | if (!IS_ERR_OR_NULL(mnt)) { | |
f7a99c5b | 2906 | real_mount(mnt)->mnt_ns = NULL; |
48a066e7 | 2907 | synchronize_rcu(); /* yecchhh... */ |
423e0ab0 TC |
2908 | mntput(mnt); |
2909 | } | |
2910 | } | |
2911 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 AV |
2912 | |
2913 | bool our_mnt(struct vfsmount *mnt) | |
2914 | { | |
143c8c91 | 2915 | return check_mnt(real_mount(mnt)); |
02125a82 | 2916 | } |
8823c079 | 2917 | |
3151527e EB |
2918 | bool current_chrooted(void) |
2919 | { | |
2920 | /* Does the current process have a non-standard root */ | |
2921 | struct path ns_root; | |
2922 | struct path fs_root; | |
2923 | bool chrooted; | |
2924 | ||
2925 | /* Find the namespace root */ | |
2926 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; | |
2927 | ns_root.dentry = ns_root.mnt->mnt_root; | |
2928 | path_get(&ns_root); | |
2929 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) | |
2930 | ; | |
2931 | ||
2932 | get_fs_root(current->fs, &fs_root); | |
2933 | ||
2934 | chrooted = !path_equal(&fs_root, &ns_root); | |
2935 | ||
2936 | path_put(&fs_root); | |
2937 | path_put(&ns_root); | |
2938 | ||
2939 | return chrooted; | |
2940 | } | |
2941 | ||
e51db735 | 2942 | bool fs_fully_visible(struct file_system_type *type) |
87a8ebd6 EB |
2943 | { |
2944 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
2945 | struct mount *mnt; | |
e51db735 | 2946 | bool visible = false; |
87a8ebd6 | 2947 | |
e51db735 EB |
2948 | if (unlikely(!ns)) |
2949 | return false; | |
2950 | ||
44bb4385 | 2951 | down_read(&namespace_sem); |
87a8ebd6 | 2952 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
e51db735 EB |
2953 | struct mount *child; |
2954 | if (mnt->mnt.mnt_sb->s_type != type) | |
2955 | continue; | |
2956 | ||
2957 | /* This mount is not fully visible if there are any child mounts | |
2958 | * that cover anything except for empty directories. | |
2959 | */ | |
2960 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
2961 | struct inode *inode = child->mnt_mountpoint->d_inode; | |
2962 | if (!S_ISDIR(inode->i_mode)) | |
2963 | goto next; | |
41301ae7 | 2964 | if (inode->i_nlink > 2) |
e51db735 | 2965 | goto next; |
87a8ebd6 | 2966 | } |
e51db735 EB |
2967 | visible = true; |
2968 | goto found; | |
2969 | next: ; | |
87a8ebd6 | 2970 | } |
e51db735 | 2971 | found: |
44bb4385 | 2972 | up_read(&namespace_sem); |
e51db735 | 2973 | return visible; |
87a8ebd6 EB |
2974 | } |
2975 | ||
8823c079 EB |
2976 | static void *mntns_get(struct task_struct *task) |
2977 | { | |
2978 | struct mnt_namespace *ns = NULL; | |
2979 | struct nsproxy *nsproxy; | |
2980 | ||
2981 | rcu_read_lock(); | |
2982 | nsproxy = task_nsproxy(task); | |
2983 | if (nsproxy) { | |
2984 | ns = nsproxy->mnt_ns; | |
2985 | get_mnt_ns(ns); | |
2986 | } | |
2987 | rcu_read_unlock(); | |
2988 | ||
2989 | return ns; | |
2990 | } | |
2991 | ||
2992 | static void mntns_put(void *ns) | |
2993 | { | |
2994 | put_mnt_ns(ns); | |
2995 | } | |
2996 | ||
2997 | static int mntns_install(struct nsproxy *nsproxy, void *ns) | |
2998 | { | |
2999 | struct fs_struct *fs = current->fs; | |
3000 | struct mnt_namespace *mnt_ns = ns; | |
3001 | struct path root; | |
3002 | ||
0c55cfc4 | 3003 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
c7b96acf EB |
3004 | !ns_capable(current_user_ns(), CAP_SYS_CHROOT) || |
3005 | !ns_capable(current_user_ns(), CAP_SYS_ADMIN)) | |
ae11e0f1 | 3006 | return -EPERM; |
8823c079 EB |
3007 | |
3008 | if (fs->users != 1) | |
3009 | return -EINVAL; | |
3010 | ||
3011 | get_mnt_ns(mnt_ns); | |
3012 | put_mnt_ns(nsproxy->mnt_ns); | |
3013 | nsproxy->mnt_ns = mnt_ns; | |
3014 | ||
3015 | /* Find the root */ | |
3016 | root.mnt = &mnt_ns->root->mnt; | |
3017 | root.dentry = mnt_ns->root->mnt.mnt_root; | |
3018 | path_get(&root); | |
3019 | while(d_mountpoint(root.dentry) && follow_down_one(&root)) | |
3020 | ; | |
3021 | ||
3022 | /* Update the pwd and root */ | |
3023 | set_fs_pwd(fs, &root); | |
3024 | set_fs_root(fs, &root); | |
3025 | ||
3026 | path_put(&root); | |
3027 | return 0; | |
3028 | } | |
3029 | ||
98f842e6 EB |
3030 | static unsigned int mntns_inum(void *ns) |
3031 | { | |
3032 | struct mnt_namespace *mnt_ns = ns; | |
3033 | return mnt_ns->proc_inum; | |
3034 | } | |
3035 | ||
8823c079 EB |
3036 | const struct proc_ns_operations mntns_operations = { |
3037 | .name = "mnt", | |
3038 | .type = CLONE_NEWNS, | |
3039 | .get = mntns_get, | |
3040 | .put = mntns_put, | |
3041 | .install = mntns_install, | |
98f842e6 | 3042 | .inum = mntns_inum, |
8823c079 | 3043 | }; |