Commit | Line | Data |
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59bd9ded | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/fs/namespace.c | |
4 | * | |
5 | * (C) Copyright Al Viro 2000, 2001 | |
1da177e4 LT |
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> | |
5b825c3a | 18 | #include <linux/cred.h> |
73cd49ec | 19 | #include <linux/idr.h> |
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 */ | |
a07b2000 | 23 | #include <linux/file.h> |
d10577a8 | 24 | #include <linux/uaccess.h> |
0bb80f24 | 25 | #include <linux/proc_ns.h> |
20b4fb48 | 26 | #include <linux/magic.h> |
57c8a661 | 27 | #include <linux/memblock.h> |
9caccd41 | 28 | #include <linux/proc_fs.h> |
9ea459e1 | 29 | #include <linux/task_work.h> |
9164bb4a | 30 | #include <linux/sched/task.h> |
e262e32d | 31 | #include <uapi/linux/mount.h> |
9bc61ab1 | 32 | #include <linux/fs_context.h> |
037f11b4 | 33 | #include <linux/shmem_fs.h> |
bd303368 | 34 | #include <linux/mnt_idmapping.h> |
9164bb4a | 35 | |
07b20889 | 36 | #include "pnode.h" |
948730b0 | 37 | #include "internal.h" |
1da177e4 | 38 | |
d2921684 | 39 | /* Maximum number of mounts in a mount namespace */ |
ab171b95 | 40 | static unsigned int sysctl_mount_max __read_mostly = 100000; |
d2921684 | 41 | |
0818bf27 AV |
42 | static unsigned int m_hash_mask __read_mostly; |
43 | static unsigned int m_hash_shift __read_mostly; | |
44 | static unsigned int mp_hash_mask __read_mostly; | |
45 | static unsigned int mp_hash_shift __read_mostly; | |
46 | ||
47 | static __initdata unsigned long mhash_entries; | |
48 | static int __init set_mhash_entries(char *str) | |
49 | { | |
50 | if (!str) | |
51 | return 0; | |
52 | mhash_entries = simple_strtoul(str, &str, 0); | |
53 | return 1; | |
54 | } | |
55 | __setup("mhash_entries=", set_mhash_entries); | |
56 | ||
57 | static __initdata unsigned long mphash_entries; | |
58 | static int __init set_mphash_entries(char *str) | |
59 | { | |
60 | if (!str) | |
61 | return 0; | |
62 | mphash_entries = simple_strtoul(str, &str, 0); | |
63 | return 1; | |
64 | } | |
65 | __setup("mphash_entries=", set_mphash_entries); | |
13f14b4d | 66 | |
c7999c36 | 67 | static u64 event; |
73cd49ec | 68 | static DEFINE_IDA(mnt_id_ida); |
719f5d7f | 69 | static DEFINE_IDA(mnt_group_ida); |
1da177e4 | 70 | |
38129a13 | 71 | static struct hlist_head *mount_hashtable __read_mostly; |
0818bf27 | 72 | static struct hlist_head *mountpoint_hashtable __read_mostly; |
e18b890b | 73 | static struct kmem_cache *mnt_cache __read_mostly; |
59aa0da8 | 74 | static DECLARE_RWSEM(namespace_sem); |
4edbe133 AV |
75 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
76 | static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ | |
1da177e4 | 77 | |
2a186721 CB |
78 | struct mount_kattr { |
79 | unsigned int attr_set; | |
80 | unsigned int attr_clr; | |
81 | unsigned int propagation; | |
82 | unsigned int lookup_flags; | |
83 | bool recurse; | |
9caccd41 | 84 | struct user_namespace *mnt_userns; |
2a186721 CB |
85 | }; |
86 | ||
f87fd4c2 | 87 | /* /sys/fs */ |
00d26666 GKH |
88 | struct kobject *fs_kobj; |
89 | EXPORT_SYMBOL_GPL(fs_kobj); | |
f87fd4c2 | 90 | |
99b7db7b NP |
91 | /* |
92 | * vfsmount lock may be taken for read to prevent changes to the | |
93 | * vfsmount hash, ie. during mountpoint lookups or walking back | |
94 | * up the tree. | |
95 | * | |
96 | * It should be taken for write in all cases where the vfsmount | |
97 | * tree or hash is modified or when a vfsmount structure is modified. | |
98 | */ | |
48a066e7 | 99 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
99b7db7b | 100 | |
d033cb67 CB |
101 | static inline void lock_mount_hash(void) |
102 | { | |
103 | write_seqlock(&mount_lock); | |
104 | } | |
105 | ||
106 | static inline void unlock_mount_hash(void) | |
107 | { | |
108 | write_sequnlock(&mount_lock); | |
109 | } | |
110 | ||
38129a13 | 111 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 112 | { |
b58fed8b RP |
113 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
114 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); | |
0818bf27 AV |
115 | tmp = tmp + (tmp >> m_hash_shift); |
116 | return &mount_hashtable[tmp & m_hash_mask]; | |
117 | } | |
118 | ||
119 | static inline struct hlist_head *mp_hash(struct dentry *dentry) | |
120 | { | |
121 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); | |
122 | tmp = tmp + (tmp >> mp_hash_shift); | |
123 | return &mountpoint_hashtable[tmp & mp_hash_mask]; | |
1da177e4 LT |
124 | } |
125 | ||
b105e270 | 126 | static int mnt_alloc_id(struct mount *mnt) |
73cd49ec | 127 | { |
169b480e MW |
128 | int res = ida_alloc(&mnt_id_ida, GFP_KERNEL); |
129 | ||
130 | if (res < 0) | |
131 | return res; | |
132 | mnt->mnt_id = res; | |
133 | return 0; | |
73cd49ec MS |
134 | } |
135 | ||
b105e270 | 136 | static void mnt_free_id(struct mount *mnt) |
73cd49ec | 137 | { |
169b480e | 138 | ida_free(&mnt_id_ida, mnt->mnt_id); |
73cd49ec MS |
139 | } |
140 | ||
719f5d7f MS |
141 | /* |
142 | * Allocate a new peer group ID | |
719f5d7f | 143 | */ |
4b8b21f4 | 144 | static int mnt_alloc_group_id(struct mount *mnt) |
719f5d7f | 145 | { |
169b480e | 146 | int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL); |
f21f6220 | 147 | |
169b480e MW |
148 | if (res < 0) |
149 | return res; | |
150 | mnt->mnt_group_id = res; | |
151 | return 0; | |
719f5d7f MS |
152 | } |
153 | ||
154 | /* | |
155 | * Release a peer group ID | |
156 | */ | |
4b8b21f4 | 157 | void mnt_release_group_id(struct mount *mnt) |
719f5d7f | 158 | { |
169b480e | 159 | ida_free(&mnt_group_ida, mnt->mnt_group_id); |
15169fe7 | 160 | mnt->mnt_group_id = 0; |
719f5d7f MS |
161 | } |
162 | ||
b3e19d92 NP |
163 | /* |
164 | * vfsmount lock must be held for read | |
165 | */ | |
83adc753 | 166 | static inline void mnt_add_count(struct mount *mnt, int n) |
b3e19d92 NP |
167 | { |
168 | #ifdef CONFIG_SMP | |
68e8a9fe | 169 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
b3e19d92 NP |
170 | #else |
171 | preempt_disable(); | |
68e8a9fe | 172 | mnt->mnt_count += n; |
b3e19d92 NP |
173 | preempt_enable(); |
174 | #endif | |
175 | } | |
176 | ||
b3e19d92 NP |
177 | /* |
178 | * vfsmount lock must be held for write | |
179 | */ | |
edf7ddbf | 180 | int mnt_get_count(struct mount *mnt) |
b3e19d92 NP |
181 | { |
182 | #ifdef CONFIG_SMP | |
edf7ddbf | 183 | int count = 0; |
b3e19d92 NP |
184 | int cpu; |
185 | ||
186 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 187 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
b3e19d92 NP |
188 | } |
189 | ||
190 | return count; | |
191 | #else | |
68e8a9fe | 192 | return mnt->mnt_count; |
b3e19d92 NP |
193 | #endif |
194 | } | |
195 | ||
b105e270 | 196 | static struct mount *alloc_vfsmnt(const char *name) |
1da177e4 | 197 | { |
c63181e6 AV |
198 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
199 | if (mnt) { | |
73cd49ec MS |
200 | int err; |
201 | ||
c63181e6 | 202 | err = mnt_alloc_id(mnt); |
88b38782 LZ |
203 | if (err) |
204 | goto out_free_cache; | |
205 | ||
206 | if (name) { | |
79f6540b VA |
207 | mnt->mnt_devname = kstrdup_const(name, |
208 | GFP_KERNEL_ACCOUNT); | |
c63181e6 | 209 | if (!mnt->mnt_devname) |
88b38782 | 210 | goto out_free_id; |
73cd49ec MS |
211 | } |
212 | ||
b3e19d92 | 213 | #ifdef CONFIG_SMP |
c63181e6 AV |
214 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
215 | if (!mnt->mnt_pcp) | |
b3e19d92 NP |
216 | goto out_free_devname; |
217 | ||
c63181e6 | 218 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
b3e19d92 | 219 | #else |
c63181e6 AV |
220 | mnt->mnt_count = 1; |
221 | mnt->mnt_writers = 0; | |
b3e19d92 NP |
222 | #endif |
223 | ||
38129a13 | 224 | INIT_HLIST_NODE(&mnt->mnt_hash); |
c63181e6 AV |
225 | INIT_LIST_HEAD(&mnt->mnt_child); |
226 | INIT_LIST_HEAD(&mnt->mnt_mounts); | |
227 | INIT_LIST_HEAD(&mnt->mnt_list); | |
228 | INIT_LIST_HEAD(&mnt->mnt_expire); | |
229 | INIT_LIST_HEAD(&mnt->mnt_share); | |
230 | INIT_LIST_HEAD(&mnt->mnt_slave_list); | |
231 | INIT_LIST_HEAD(&mnt->mnt_slave); | |
0a5eb7c8 | 232 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
99b19d16 | 233 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
56cbb429 | 234 | INIT_HLIST_HEAD(&mnt->mnt_stuck_children); |
a6435940 | 235 | mnt->mnt.mnt_userns = &init_user_ns; |
1da177e4 | 236 | } |
c63181e6 | 237 | return mnt; |
88b38782 | 238 | |
d3ef3d73 | 239 | #ifdef CONFIG_SMP |
240 | out_free_devname: | |
fcc139ae | 241 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 242 | #endif |
88b38782 | 243 | out_free_id: |
c63181e6 | 244 | mnt_free_id(mnt); |
88b38782 | 245 | out_free_cache: |
c63181e6 | 246 | kmem_cache_free(mnt_cache, mnt); |
88b38782 | 247 | return NULL; |
1da177e4 LT |
248 | } |
249 | ||
3d733633 DH |
250 | /* |
251 | * Most r/o checks on a fs are for operations that take | |
252 | * discrete amounts of time, like a write() or unlink(). | |
253 | * We must keep track of when those operations start | |
254 | * (for permission checks) and when they end, so that | |
255 | * we can determine when writes are able to occur to | |
256 | * a filesystem. | |
257 | */ | |
258 | /* | |
259 | * __mnt_is_readonly: check whether a mount is read-only | |
260 | * @mnt: the mount to check for its write status | |
261 | * | |
262 | * This shouldn't be used directly ouside of the VFS. | |
263 | * It does not guarantee that the filesystem will stay | |
264 | * r/w, just that it is right *now*. This can not and | |
265 | * should not be used in place of IS_RDONLY(inode). | |
266 | * mnt_want/drop_write() will _keep_ the filesystem | |
267 | * r/w. | |
268 | */ | |
43f5e655 | 269 | bool __mnt_is_readonly(struct vfsmount *mnt) |
3d733633 | 270 | { |
43f5e655 | 271 | return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb); |
3d733633 DH |
272 | } |
273 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); | |
274 | ||
83adc753 | 275 | static inline void mnt_inc_writers(struct mount *mnt) |
d3ef3d73 | 276 | { |
277 | #ifdef CONFIG_SMP | |
68e8a9fe | 278 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 279 | #else |
68e8a9fe | 280 | mnt->mnt_writers++; |
d3ef3d73 | 281 | #endif |
282 | } | |
3d733633 | 283 | |
83adc753 | 284 | static inline void mnt_dec_writers(struct mount *mnt) |
3d733633 | 285 | { |
d3ef3d73 | 286 | #ifdef CONFIG_SMP |
68e8a9fe | 287 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
d3ef3d73 | 288 | #else |
68e8a9fe | 289 | mnt->mnt_writers--; |
d3ef3d73 | 290 | #endif |
3d733633 | 291 | } |
3d733633 | 292 | |
83adc753 | 293 | static unsigned int mnt_get_writers(struct mount *mnt) |
3d733633 | 294 | { |
d3ef3d73 | 295 | #ifdef CONFIG_SMP |
296 | unsigned int count = 0; | |
3d733633 | 297 | int cpu; |
3d733633 DH |
298 | |
299 | for_each_possible_cpu(cpu) { | |
68e8a9fe | 300 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
3d733633 | 301 | } |
3d733633 | 302 | |
d3ef3d73 | 303 | return count; |
304 | #else | |
305 | return mnt->mnt_writers; | |
306 | #endif | |
3d733633 DH |
307 | } |
308 | ||
4ed5e82f MS |
309 | static int mnt_is_readonly(struct vfsmount *mnt) |
310 | { | |
311 | if (mnt->mnt_sb->s_readonly_remount) | |
312 | return 1; | |
313 | /* Order wrt setting s_flags/s_readonly_remount in do_remount() */ | |
314 | smp_rmb(); | |
315 | return __mnt_is_readonly(mnt); | |
316 | } | |
317 | ||
8366025e | 318 | /* |
eb04c282 JK |
319 | * Most r/o & frozen checks on a fs are for operations that take discrete |
320 | * amounts of time, like a write() or unlink(). We must keep track of when | |
321 | * those operations start (for permission checks) and when they end, so that we | |
322 | * can determine when writes are able to occur to a filesystem. | |
8366025e DH |
323 | */ |
324 | /** | |
eb04c282 | 325 | * __mnt_want_write - get write access to a mount without freeze protection |
83adc753 | 326 | * @m: the mount on which to take a write |
8366025e | 327 | * |
eb04c282 JK |
328 | * This tells the low-level filesystem that a write is about to be performed to |
329 | * it, and makes sure that writes are allowed (mnt it read-write) before | |
330 | * returning success. This operation does not protect against filesystem being | |
331 | * frozen. When the write operation is finished, __mnt_drop_write() must be | |
332 | * called. This is effectively a refcount. | |
8366025e | 333 | */ |
eb04c282 | 334 | int __mnt_want_write(struct vfsmount *m) |
8366025e | 335 | { |
83adc753 | 336 | struct mount *mnt = real_mount(m); |
3d733633 | 337 | int ret = 0; |
3d733633 | 338 | |
d3ef3d73 | 339 | preempt_disable(); |
c6653a83 | 340 | mnt_inc_writers(mnt); |
d3ef3d73 | 341 | /* |
c6653a83 | 342 | * The store to mnt_inc_writers must be visible before we pass |
d3ef3d73 | 343 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
344 | * incremented count after it has set MNT_WRITE_HOLD. | |
345 | */ | |
346 | smp_mb(); | |
0f8821da SAS |
347 | might_lock(&mount_lock.lock); |
348 | while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) { | |
349 | if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { | |
350 | cpu_relax(); | |
351 | } else { | |
352 | /* | |
353 | * This prevents priority inversion, if the task | |
354 | * setting MNT_WRITE_HOLD got preempted on a remote | |
355 | * CPU, and it prevents life lock if the task setting | |
356 | * MNT_WRITE_HOLD has a lower priority and is bound to | |
357 | * the same CPU as the task that is spinning here. | |
358 | */ | |
359 | preempt_enable(); | |
360 | lock_mount_hash(); | |
361 | unlock_mount_hash(); | |
362 | preempt_disable(); | |
363 | } | |
364 | } | |
d3ef3d73 | 365 | /* |
366 | * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will | |
367 | * be set to match its requirements. So we must not load that until | |
368 | * MNT_WRITE_HOLD is cleared. | |
369 | */ | |
370 | smp_rmb(); | |
4ed5e82f | 371 | if (mnt_is_readonly(m)) { |
c6653a83 | 372 | mnt_dec_writers(mnt); |
3d733633 | 373 | ret = -EROFS; |
3d733633 | 374 | } |
d3ef3d73 | 375 | preempt_enable(); |
eb04c282 JK |
376 | |
377 | return ret; | |
378 | } | |
379 | ||
380 | /** | |
381 | * mnt_want_write - get write access to a mount | |
382 | * @m: the mount on which to take a write | |
383 | * | |
384 | * This tells the low-level filesystem that a write is about to be performed to | |
385 | * it, and makes sure that writes are allowed (mount is read-write, filesystem | |
386 | * is not frozen) before returning success. When the write operation is | |
387 | * finished, mnt_drop_write() must be called. This is effectively a refcount. | |
388 | */ | |
389 | int mnt_want_write(struct vfsmount *m) | |
390 | { | |
391 | int ret; | |
392 | ||
393 | sb_start_write(m->mnt_sb); | |
394 | ret = __mnt_want_write(m); | |
395 | if (ret) | |
396 | sb_end_write(m->mnt_sb); | |
3d733633 | 397 | return ret; |
8366025e DH |
398 | } |
399 | EXPORT_SYMBOL_GPL(mnt_want_write); | |
400 | ||
96029c4e | 401 | /** |
eb04c282 | 402 | * __mnt_want_write_file - get write access to a file's mount |
96029c4e | 403 | * @file: the file who's mount on which to take a write |
404 | * | |
14e43bf4 EB |
405 | * This is like __mnt_want_write, but if the file is already open for writing it |
406 | * skips incrementing mnt_writers (since the open file already has a reference) | |
407 | * and instead only does the check for emergency r/o remounts. This must be | |
408 | * paired with __mnt_drop_write_file. | |
96029c4e | 409 | */ |
eb04c282 | 410 | int __mnt_want_write_file(struct file *file) |
96029c4e | 411 | { |
14e43bf4 EB |
412 | if (file->f_mode & FMODE_WRITER) { |
413 | /* | |
414 | * Superblock may have become readonly while there are still | |
415 | * writable fd's, e.g. due to a fs error with errors=remount-ro | |
416 | */ | |
417 | if (__mnt_is_readonly(file->f_path.mnt)) | |
418 | return -EROFS; | |
419 | return 0; | |
420 | } | |
421 | return __mnt_want_write(file->f_path.mnt); | |
96029c4e | 422 | } |
eb04c282 | 423 | |
7c6893e3 MS |
424 | /** |
425 | * mnt_want_write_file - get write access to a file's mount | |
426 | * @file: the file who's mount on which to take a write | |
427 | * | |
14e43bf4 EB |
428 | * This is like mnt_want_write, but if the file is already open for writing it |
429 | * skips incrementing mnt_writers (since the open file already has a reference) | |
430 | * and instead only does the freeze protection and the check for emergency r/o | |
431 | * remounts. This must be paired with mnt_drop_write_file. | |
7c6893e3 MS |
432 | */ |
433 | int mnt_want_write_file(struct file *file) | |
434 | { | |
435 | int ret; | |
436 | ||
a6795a58 | 437 | sb_start_write(file_inode(file)->i_sb); |
eb04c282 JK |
438 | ret = __mnt_want_write_file(file); |
439 | if (ret) | |
a6795a58 | 440 | sb_end_write(file_inode(file)->i_sb); |
7c6893e3 MS |
441 | return ret; |
442 | } | |
96029c4e | 443 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
444 | ||
8366025e | 445 | /** |
eb04c282 | 446 | * __mnt_drop_write - give up write access to a mount |
8366025e DH |
447 | * @mnt: the mount on which to give up write access |
448 | * | |
449 | * Tells the low-level filesystem that we are done | |
450 | * performing writes to it. Must be matched with | |
eb04c282 | 451 | * __mnt_want_write() call above. |
8366025e | 452 | */ |
eb04c282 | 453 | void __mnt_drop_write(struct vfsmount *mnt) |
8366025e | 454 | { |
d3ef3d73 | 455 | preempt_disable(); |
83adc753 | 456 | mnt_dec_writers(real_mount(mnt)); |
d3ef3d73 | 457 | preempt_enable(); |
8366025e | 458 | } |
eb04c282 JK |
459 | |
460 | /** | |
461 | * mnt_drop_write - give up write access to a mount | |
462 | * @mnt: the mount on which to give up write access | |
463 | * | |
464 | * Tells the low-level filesystem that we are done performing writes to it and | |
465 | * also allows filesystem to be frozen again. Must be matched with | |
466 | * mnt_want_write() call above. | |
467 | */ | |
468 | void mnt_drop_write(struct vfsmount *mnt) | |
469 | { | |
470 | __mnt_drop_write(mnt); | |
471 | sb_end_write(mnt->mnt_sb); | |
472 | } | |
8366025e DH |
473 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
474 | ||
eb04c282 JK |
475 | void __mnt_drop_write_file(struct file *file) |
476 | { | |
14e43bf4 EB |
477 | if (!(file->f_mode & FMODE_WRITER)) |
478 | __mnt_drop_write(file->f_path.mnt); | |
eb04c282 JK |
479 | } |
480 | ||
7c6893e3 MS |
481 | void mnt_drop_write_file(struct file *file) |
482 | { | |
a6795a58 | 483 | __mnt_drop_write_file(file); |
7c6893e3 MS |
484 | sb_end_write(file_inode(file)->i_sb); |
485 | } | |
2a79f17e AV |
486 | EXPORT_SYMBOL(mnt_drop_write_file); |
487 | ||
538f4f02 CB |
488 | /** |
489 | * mnt_hold_writers - prevent write access to the given mount | |
490 | * @mnt: mnt to prevent write access to | |
491 | * | |
492 | * Prevents write access to @mnt if there are no active writers for @mnt. | |
493 | * This function needs to be called and return successfully before changing | |
494 | * properties of @mnt that need to remain stable for callers with write access | |
495 | * to @mnt. | |
496 | * | |
497 | * After this functions has been called successfully callers must pair it with | |
498 | * a call to mnt_unhold_writers() in order to stop preventing write access to | |
499 | * @mnt. | |
500 | * | |
501 | * Context: This function expects lock_mount_hash() to be held serializing | |
502 | * setting MNT_WRITE_HOLD. | |
503 | * Return: On success 0 is returned. | |
504 | * On error, -EBUSY is returned. | |
505 | */ | |
fbdc2f6c | 506 | static inline int mnt_hold_writers(struct mount *mnt) |
8366025e | 507 | { |
83adc753 | 508 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
3d733633 | 509 | /* |
d3ef3d73 | 510 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
511 | * should be visible before we do. | |
3d733633 | 512 | */ |
d3ef3d73 | 513 | smp_mb(); |
514 | ||
3d733633 | 515 | /* |
d3ef3d73 | 516 | * With writers on hold, if this value is zero, then there are |
517 | * definitely no active writers (although held writers may subsequently | |
518 | * increment the count, they'll have to wait, and decrement it after | |
519 | * seeing MNT_READONLY). | |
520 | * | |
521 | * It is OK to have counter incremented on one CPU and decremented on | |
522 | * another: the sum will add up correctly. The danger would be when we | |
523 | * sum up each counter, if we read a counter before it is incremented, | |
524 | * but then read another CPU's count which it has been subsequently | |
525 | * decremented from -- we would see more decrements than we should. | |
526 | * MNT_WRITE_HOLD protects against this scenario, because | |
527 | * mnt_want_write first increments count, then smp_mb, then spins on | |
528 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while | |
529 | * we're counting up here. | |
3d733633 | 530 | */ |
c6653a83 | 531 | if (mnt_get_writers(mnt) > 0) |
fbdc2f6c CB |
532 | return -EBUSY; |
533 | ||
534 | return 0; | |
535 | } | |
536 | ||
538f4f02 CB |
537 | /** |
538 | * mnt_unhold_writers - stop preventing write access to the given mount | |
539 | * @mnt: mnt to stop preventing write access to | |
540 | * | |
541 | * Stop preventing write access to @mnt allowing callers to gain write access | |
542 | * to @mnt again. | |
543 | * | |
544 | * This function can only be called after a successful call to | |
545 | * mnt_hold_writers(). | |
546 | * | |
547 | * Context: This function expects lock_mount_hash() to be held. | |
548 | */ | |
fbdc2f6c CB |
549 | static inline void mnt_unhold_writers(struct mount *mnt) |
550 | { | |
d3ef3d73 | 551 | /* |
552 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers | |
553 | * that become unheld will see MNT_READONLY. | |
554 | */ | |
555 | smp_wmb(); | |
83adc753 | 556 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
fbdc2f6c CB |
557 | } |
558 | ||
559 | static int mnt_make_readonly(struct mount *mnt) | |
560 | { | |
561 | int ret; | |
562 | ||
563 | ret = mnt_hold_writers(mnt); | |
564 | if (!ret) | |
565 | mnt->mnt.mnt_flags |= MNT_READONLY; | |
566 | mnt_unhold_writers(mnt); | |
3d733633 | 567 | return ret; |
8366025e | 568 | } |
8366025e | 569 | |
4ed5e82f MS |
570 | int sb_prepare_remount_readonly(struct super_block *sb) |
571 | { | |
572 | struct mount *mnt; | |
573 | int err = 0; | |
574 | ||
8e8b8796 MS |
575 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
576 | if (atomic_long_read(&sb->s_remove_count)) | |
577 | return -EBUSY; | |
578 | ||
719ea2fb | 579 | lock_mount_hash(); |
4ed5e82f MS |
580 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
581 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { | |
ad1844a0 CB |
582 | err = mnt_hold_writers(mnt); |
583 | if (err) | |
4ed5e82f | 584 | break; |
4ed5e82f MS |
585 | } |
586 | } | |
8e8b8796 MS |
587 | if (!err && atomic_long_read(&sb->s_remove_count)) |
588 | err = -EBUSY; | |
589 | ||
4ed5e82f MS |
590 | if (!err) { |
591 | sb->s_readonly_remount = 1; | |
592 | smp_wmb(); | |
593 | } | |
594 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { | |
595 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) | |
596 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; | |
597 | } | |
719ea2fb | 598 | unlock_mount_hash(); |
4ed5e82f MS |
599 | |
600 | return err; | |
601 | } | |
602 | ||
b105e270 | 603 | static void free_vfsmnt(struct mount *mnt) |
1da177e4 | 604 | { |
a6435940 CB |
605 | struct user_namespace *mnt_userns; |
606 | ||
607 | mnt_userns = mnt_user_ns(&mnt->mnt); | |
bd303368 | 608 | if (!initial_idmapping(mnt_userns)) |
a6435940 | 609 | put_user_ns(mnt_userns); |
fcc139ae | 610 | kfree_const(mnt->mnt_devname); |
d3ef3d73 | 611 | #ifdef CONFIG_SMP |
68e8a9fe | 612 | free_percpu(mnt->mnt_pcp); |
d3ef3d73 | 613 | #endif |
b105e270 | 614 | kmem_cache_free(mnt_cache, mnt); |
1da177e4 LT |
615 | } |
616 | ||
8ffcb32e DH |
617 | static void delayed_free_vfsmnt(struct rcu_head *head) |
618 | { | |
619 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); | |
620 | } | |
621 | ||
48a066e7 | 622 | /* call under rcu_read_lock */ |
294d71ff | 623 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
48a066e7 AV |
624 | { |
625 | struct mount *mnt; | |
626 | if (read_seqretry(&mount_lock, seq)) | |
294d71ff | 627 | return 1; |
48a066e7 | 628 | if (bastard == NULL) |
294d71ff | 629 | return 0; |
48a066e7 AV |
630 | mnt = real_mount(bastard); |
631 | mnt_add_count(mnt, 1); | |
119e1ef8 | 632 | smp_mb(); // see mntput_no_expire() |
48a066e7 | 633 | if (likely(!read_seqretry(&mount_lock, seq))) |
294d71ff | 634 | return 0; |
48a066e7 AV |
635 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
636 | mnt_add_count(mnt, -1); | |
294d71ff AV |
637 | return 1; |
638 | } | |
119e1ef8 AV |
639 | lock_mount_hash(); |
640 | if (unlikely(bastard->mnt_flags & MNT_DOOMED)) { | |
641 | mnt_add_count(mnt, -1); | |
642 | unlock_mount_hash(); | |
643 | return 1; | |
644 | } | |
645 | unlock_mount_hash(); | |
646 | /* caller will mntput() */ | |
294d71ff AV |
647 | return -1; |
648 | } | |
649 | ||
650 | /* call under rcu_read_lock */ | |
651 | bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) | |
652 | { | |
653 | int res = __legitimize_mnt(bastard, seq); | |
654 | if (likely(!res)) | |
655 | return true; | |
656 | if (unlikely(res < 0)) { | |
657 | rcu_read_unlock(); | |
658 | mntput(bastard); | |
659 | rcu_read_lock(); | |
48a066e7 | 660 | } |
48a066e7 AV |
661 | return false; |
662 | } | |
663 | ||
1da177e4 | 664 | /* |
474279dc | 665 | * find the first mount at @dentry on vfsmount @mnt. |
48a066e7 | 666 | * call under rcu_read_lock() |
1da177e4 | 667 | */ |
474279dc | 668 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
1da177e4 | 669 | { |
38129a13 | 670 | struct hlist_head *head = m_hash(mnt, dentry); |
474279dc AV |
671 | struct mount *p; |
672 | ||
38129a13 | 673 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
474279dc AV |
674 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
675 | return p; | |
676 | return NULL; | |
677 | } | |
678 | ||
a05964f3 | 679 | /* |
f015f126 DH |
680 | * lookup_mnt - Return the first child mount mounted at path |
681 | * | |
682 | * "First" means first mounted chronologically. If you create the | |
683 | * following mounts: | |
684 | * | |
685 | * mount /dev/sda1 /mnt | |
686 | * mount /dev/sda2 /mnt | |
687 | * mount /dev/sda3 /mnt | |
688 | * | |
689 | * Then lookup_mnt() on the base /mnt dentry in the root mount will | |
690 | * return successively the root dentry and vfsmount of /dev/sda1, then | |
691 | * /dev/sda2, then /dev/sda3, then NULL. | |
692 | * | |
693 | * lookup_mnt takes a reference to the found vfsmount. | |
a05964f3 | 694 | */ |
ca71cf71 | 695 | struct vfsmount *lookup_mnt(const struct path *path) |
a05964f3 | 696 | { |
c7105365 | 697 | struct mount *child_mnt; |
48a066e7 AV |
698 | struct vfsmount *m; |
699 | unsigned seq; | |
99b7db7b | 700 | |
48a066e7 AV |
701 | rcu_read_lock(); |
702 | do { | |
703 | seq = read_seqbegin(&mount_lock); | |
704 | child_mnt = __lookup_mnt(path->mnt, path->dentry); | |
705 | m = child_mnt ? &child_mnt->mnt : NULL; | |
706 | } while (!legitimize_mnt(m, seq)); | |
707 | rcu_read_unlock(); | |
708 | return m; | |
a05964f3 RP |
709 | } |
710 | ||
9f6c61f9 MS |
711 | static inline void lock_ns_list(struct mnt_namespace *ns) |
712 | { | |
713 | spin_lock(&ns->ns_lock); | |
714 | } | |
715 | ||
716 | static inline void unlock_ns_list(struct mnt_namespace *ns) | |
717 | { | |
718 | spin_unlock(&ns->ns_lock); | |
719 | } | |
720 | ||
721 | static inline bool mnt_is_cursor(struct mount *mnt) | |
722 | { | |
723 | return mnt->mnt.mnt_flags & MNT_CURSOR; | |
724 | } | |
725 | ||
7af1364f EB |
726 | /* |
727 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the | |
728 | * current mount namespace. | |
729 | * | |
730 | * The common case is dentries are not mountpoints at all and that | |
731 | * test is handled inline. For the slow case when we are actually | |
732 | * dealing with a mountpoint of some kind, walk through all of the | |
733 | * mounts in the current mount namespace and test to see if the dentry | |
734 | * is a mountpoint. | |
735 | * | |
736 | * The mount_hashtable is not usable in the context because we | |
737 | * need to identify all mounts that may be in the current mount | |
738 | * namespace not just a mount that happens to have some specified | |
739 | * parent mount. | |
740 | */ | |
741 | bool __is_local_mountpoint(struct dentry *dentry) | |
742 | { | |
743 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; | |
744 | struct mount *mnt; | |
745 | bool is_covered = false; | |
746 | ||
7af1364f | 747 | down_read(&namespace_sem); |
9f6c61f9 | 748 | lock_ns_list(ns); |
7af1364f | 749 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
9f6c61f9 MS |
750 | if (mnt_is_cursor(mnt)) |
751 | continue; | |
7af1364f EB |
752 | is_covered = (mnt->mnt_mountpoint == dentry); |
753 | if (is_covered) | |
754 | break; | |
755 | } | |
9f6c61f9 | 756 | unlock_ns_list(ns); |
7af1364f | 757 | up_read(&namespace_sem); |
5ad05cc8 | 758 | |
7af1364f EB |
759 | return is_covered; |
760 | } | |
761 | ||
e2dfa935 | 762 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
84d17192 | 763 | { |
0818bf27 | 764 | struct hlist_head *chain = mp_hash(dentry); |
84d17192 AV |
765 | struct mountpoint *mp; |
766 | ||
0818bf27 | 767 | hlist_for_each_entry(mp, chain, m_hash) { |
84d17192 | 768 | if (mp->m_dentry == dentry) { |
84d17192 AV |
769 | mp->m_count++; |
770 | return mp; | |
771 | } | |
772 | } | |
e2dfa935 EB |
773 | return NULL; |
774 | } | |
775 | ||
3895dbf8 | 776 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
e2dfa935 | 777 | { |
3895dbf8 | 778 | struct mountpoint *mp, *new = NULL; |
e2dfa935 | 779 | int ret; |
84d17192 | 780 | |
3895dbf8 | 781 | if (d_mountpoint(dentry)) { |
1e9c75fb BC |
782 | /* might be worth a WARN_ON() */ |
783 | if (d_unlinked(dentry)) | |
784 | return ERR_PTR(-ENOENT); | |
3895dbf8 EB |
785 | mountpoint: |
786 | read_seqlock_excl(&mount_lock); | |
787 | mp = lookup_mountpoint(dentry); | |
788 | read_sequnlock_excl(&mount_lock); | |
789 | if (mp) | |
790 | goto done; | |
791 | } | |
792 | ||
793 | if (!new) | |
794 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); | |
795 | if (!new) | |
84d17192 AV |
796 | return ERR_PTR(-ENOMEM); |
797 | ||
3895dbf8 EB |
798 | |
799 | /* Exactly one processes may set d_mounted */ | |
eed81007 | 800 | ret = d_set_mounted(dentry); |
eed81007 | 801 | |
3895dbf8 EB |
802 | /* Someone else set d_mounted? */ |
803 | if (ret == -EBUSY) | |
804 | goto mountpoint; | |
805 | ||
806 | /* The dentry is not available as a mountpoint? */ | |
807 | mp = ERR_PTR(ret); | |
808 | if (ret) | |
809 | goto done; | |
810 | ||
811 | /* Add the new mountpoint to the hash table */ | |
812 | read_seqlock_excl(&mount_lock); | |
4edbe133 | 813 | new->m_dentry = dget(dentry); |
3895dbf8 EB |
814 | new->m_count = 1; |
815 | hlist_add_head(&new->m_hash, mp_hash(dentry)); | |
816 | INIT_HLIST_HEAD(&new->m_list); | |
817 | read_sequnlock_excl(&mount_lock); | |
818 | ||
819 | mp = new; | |
820 | new = NULL; | |
821 | done: | |
822 | kfree(new); | |
84d17192 AV |
823 | return mp; |
824 | } | |
825 | ||
4edbe133 AV |
826 | /* |
827 | * vfsmount lock must be held. Additionally, the caller is responsible | |
828 | * for serializing calls for given disposal list. | |
829 | */ | |
830 | static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) | |
84d17192 AV |
831 | { |
832 | if (!--mp->m_count) { | |
833 | struct dentry *dentry = mp->m_dentry; | |
0a5eb7c8 | 834 | BUG_ON(!hlist_empty(&mp->m_list)); |
84d17192 AV |
835 | spin_lock(&dentry->d_lock); |
836 | dentry->d_flags &= ~DCACHE_MOUNTED; | |
837 | spin_unlock(&dentry->d_lock); | |
4edbe133 | 838 | dput_to_list(dentry, list); |
0818bf27 | 839 | hlist_del(&mp->m_hash); |
84d17192 AV |
840 | kfree(mp); |
841 | } | |
842 | } | |
843 | ||
4edbe133 AV |
844 | /* called with namespace_lock and vfsmount lock */ |
845 | static void put_mountpoint(struct mountpoint *mp) | |
846 | { | |
847 | __put_mountpoint(mp, &ex_mountpoints); | |
848 | } | |
849 | ||
143c8c91 | 850 | static inline int check_mnt(struct mount *mnt) |
1da177e4 | 851 | { |
6b3286ed | 852 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
1da177e4 LT |
853 | } |
854 | ||
99b7db7b NP |
855 | /* |
856 | * vfsmount lock must be held for write | |
857 | */ | |
6b3286ed | 858 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
859 | { |
860 | if (ns) { | |
861 | ns->event = ++event; | |
862 | wake_up_interruptible(&ns->poll); | |
863 | } | |
864 | } | |
865 | ||
99b7db7b NP |
866 | /* |
867 | * vfsmount lock must be held for write | |
868 | */ | |
6b3286ed | 869 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
5addc5dd AV |
870 | { |
871 | if (ns && ns->event != event) { | |
872 | ns->event = event; | |
873 | wake_up_interruptible(&ns->poll); | |
874 | } | |
875 | } | |
876 | ||
99b7db7b NP |
877 | /* |
878 | * vfsmount lock must be held for write | |
879 | */ | |
e4e59906 | 880 | static struct mountpoint *unhash_mnt(struct mount *mnt) |
419148da | 881 | { |
e4e59906 | 882 | struct mountpoint *mp; |
0714a533 | 883 | mnt->mnt_parent = mnt; |
a73324da | 884 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
6b41d536 | 885 | list_del_init(&mnt->mnt_child); |
38129a13 | 886 | hlist_del_init_rcu(&mnt->mnt_hash); |
0a5eb7c8 | 887 | hlist_del_init(&mnt->mnt_mp_list); |
e4e59906 | 888 | mp = mnt->mnt_mp; |
84d17192 | 889 | mnt->mnt_mp = NULL; |
e4e59906 | 890 | return mp; |
7bdb11de EB |
891 | } |
892 | ||
6a46c573 EB |
893 | /* |
894 | * vfsmount lock must be held for write | |
895 | */ | |
896 | static void umount_mnt(struct mount *mnt) | |
897 | { | |
e4e59906 | 898 | put_mountpoint(unhash_mnt(mnt)); |
6a46c573 EB |
899 | } |
900 | ||
99b7db7b NP |
901 | /* |
902 | * vfsmount lock must be held for write | |
903 | */ | |
84d17192 AV |
904 | void mnt_set_mountpoint(struct mount *mnt, |
905 | struct mountpoint *mp, | |
44d964d6 | 906 | struct mount *child_mnt) |
b90fa9ae | 907 | { |
84d17192 | 908 | mp->m_count++; |
3a2393d7 | 909 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
4edbe133 | 910 | child_mnt->mnt_mountpoint = mp->m_dentry; |
3a2393d7 | 911 | child_mnt->mnt_parent = mnt; |
84d17192 | 912 | child_mnt->mnt_mp = mp; |
0a5eb7c8 | 913 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
b90fa9ae RP |
914 | } |
915 | ||
1064f874 EB |
916 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
917 | { | |
918 | hlist_add_head_rcu(&mnt->mnt_hash, | |
919 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); | |
920 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); | |
921 | } | |
922 | ||
99b7db7b NP |
923 | /* |
924 | * vfsmount lock must be held for write | |
925 | */ | |
84d17192 AV |
926 | static void attach_mnt(struct mount *mnt, |
927 | struct mount *parent, | |
928 | struct mountpoint *mp) | |
1da177e4 | 929 | { |
84d17192 | 930 | mnt_set_mountpoint(parent, mp, mnt); |
1064f874 | 931 | __attach_mnt(mnt, parent); |
b90fa9ae RP |
932 | } |
933 | ||
1064f874 | 934 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
12a5b529 | 935 | { |
1064f874 | 936 | struct mountpoint *old_mp = mnt->mnt_mp; |
1064f874 EB |
937 | struct mount *old_parent = mnt->mnt_parent; |
938 | ||
939 | list_del_init(&mnt->mnt_child); | |
940 | hlist_del_init(&mnt->mnt_mp_list); | |
941 | hlist_del_init_rcu(&mnt->mnt_hash); | |
942 | ||
943 | attach_mnt(mnt, parent, mp); | |
944 | ||
945 | put_mountpoint(old_mp); | |
1064f874 | 946 | mnt_add_count(old_parent, -1); |
12a5b529 AV |
947 | } |
948 | ||
b90fa9ae | 949 | /* |
99b7db7b | 950 | * vfsmount lock must be held for write |
b90fa9ae | 951 | */ |
1064f874 | 952 | static void commit_tree(struct mount *mnt) |
b90fa9ae | 953 | { |
0714a533 | 954 | struct mount *parent = mnt->mnt_parent; |
83adc753 | 955 | struct mount *m; |
b90fa9ae | 956 | LIST_HEAD(head); |
143c8c91 | 957 | struct mnt_namespace *n = parent->mnt_ns; |
b90fa9ae | 958 | |
0714a533 | 959 | BUG_ON(parent == mnt); |
b90fa9ae | 960 | |
1a4eeaf2 | 961 | list_add_tail(&head, &mnt->mnt_list); |
f7a99c5b | 962 | list_for_each_entry(m, &head, mnt_list) |
143c8c91 | 963 | m->mnt_ns = n; |
f03c6599 | 964 | |
b90fa9ae RP |
965 | list_splice(&head, n->list.prev); |
966 | ||
d2921684 EB |
967 | n->mounts += n->pending_mounts; |
968 | n->pending_mounts = 0; | |
969 | ||
1064f874 | 970 | __attach_mnt(mnt, parent); |
6b3286ed | 971 | touch_mnt_namespace(n); |
1da177e4 LT |
972 | } |
973 | ||
909b0a88 | 974 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
1da177e4 | 975 | { |
6b41d536 AV |
976 | struct list_head *next = p->mnt_mounts.next; |
977 | if (next == &p->mnt_mounts) { | |
1da177e4 | 978 | while (1) { |
909b0a88 | 979 | if (p == root) |
1da177e4 | 980 | return NULL; |
6b41d536 AV |
981 | next = p->mnt_child.next; |
982 | if (next != &p->mnt_parent->mnt_mounts) | |
1da177e4 | 983 | break; |
0714a533 | 984 | p = p->mnt_parent; |
1da177e4 LT |
985 | } |
986 | } | |
6b41d536 | 987 | return list_entry(next, struct mount, mnt_child); |
1da177e4 LT |
988 | } |
989 | ||
315fc83e | 990 | static struct mount *skip_mnt_tree(struct mount *p) |
9676f0c6 | 991 | { |
6b41d536 AV |
992 | struct list_head *prev = p->mnt_mounts.prev; |
993 | while (prev != &p->mnt_mounts) { | |
994 | p = list_entry(prev, struct mount, mnt_child); | |
995 | prev = p->mnt_mounts.prev; | |
9676f0c6 RP |
996 | } |
997 | return p; | |
998 | } | |
999 | ||
8f291889 AV |
1000 | /** |
1001 | * vfs_create_mount - Create a mount for a configured superblock | |
1002 | * @fc: The configuration context with the superblock attached | |
1003 | * | |
1004 | * Create a mount to an already configured superblock. If necessary, the | |
1005 | * caller should invoke vfs_get_tree() before calling this. | |
1006 | * | |
1007 | * Note that this does not attach the mount to anything. | |
1008 | */ | |
1009 | struct vfsmount *vfs_create_mount(struct fs_context *fc) | |
9d412a43 | 1010 | { |
b105e270 | 1011 | struct mount *mnt; |
bd303368 | 1012 | struct user_namespace *fs_userns; |
9d412a43 | 1013 | |
8f291889 AV |
1014 | if (!fc->root) |
1015 | return ERR_PTR(-EINVAL); | |
9d412a43 | 1016 | |
8f291889 | 1017 | mnt = alloc_vfsmnt(fc->source ?: "none"); |
9d412a43 AV |
1018 | if (!mnt) |
1019 | return ERR_PTR(-ENOMEM); | |
1020 | ||
8f291889 | 1021 | if (fc->sb_flags & SB_KERNMOUNT) |
b105e270 | 1022 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
9d412a43 | 1023 | |
8f291889 AV |
1024 | atomic_inc(&fc->root->d_sb->s_active); |
1025 | mnt->mnt.mnt_sb = fc->root->d_sb; | |
1026 | mnt->mnt.mnt_root = dget(fc->root); | |
1027 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1028 | mnt->mnt_parent = mnt; | |
9d412a43 | 1029 | |
bd303368 CB |
1030 | fs_userns = mnt->mnt.mnt_sb->s_user_ns; |
1031 | if (!initial_idmapping(fs_userns)) | |
1032 | mnt->mnt.mnt_userns = get_user_ns(fs_userns); | |
1033 | ||
719ea2fb | 1034 | lock_mount_hash(); |
8f291889 | 1035 | list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); |
719ea2fb | 1036 | unlock_mount_hash(); |
b105e270 | 1037 | return &mnt->mnt; |
9d412a43 | 1038 | } |
8f291889 AV |
1039 | EXPORT_SYMBOL(vfs_create_mount); |
1040 | ||
1041 | struct vfsmount *fc_mount(struct fs_context *fc) | |
1042 | { | |
1043 | int err = vfs_get_tree(fc); | |
1044 | if (!err) { | |
1045 | up_write(&fc->root->d_sb->s_umount); | |
1046 | return vfs_create_mount(fc); | |
1047 | } | |
1048 | return ERR_PTR(err); | |
1049 | } | |
1050 | EXPORT_SYMBOL(fc_mount); | |
1051 | ||
9bc61ab1 DH |
1052 | struct vfsmount *vfs_kern_mount(struct file_system_type *type, |
1053 | int flags, const char *name, | |
1054 | void *data) | |
9d412a43 | 1055 | { |
9bc61ab1 | 1056 | struct fs_context *fc; |
8f291889 | 1057 | struct vfsmount *mnt; |
9bc61ab1 | 1058 | int ret = 0; |
9d412a43 AV |
1059 | |
1060 | if (!type) | |
3e1aeb00 | 1061 | return ERR_PTR(-EINVAL); |
9d412a43 | 1062 | |
9bc61ab1 DH |
1063 | fc = fs_context_for_mount(type, flags); |
1064 | if (IS_ERR(fc)) | |
1065 | return ERR_CAST(fc); | |
1066 | ||
3e1aeb00 DH |
1067 | if (name) |
1068 | ret = vfs_parse_fs_string(fc, "source", | |
1069 | name, strlen(name)); | |
9bc61ab1 DH |
1070 | if (!ret) |
1071 | ret = parse_monolithic_mount_data(fc, data); | |
1072 | if (!ret) | |
8f291889 AV |
1073 | mnt = fc_mount(fc); |
1074 | else | |
1075 | mnt = ERR_PTR(ret); | |
9d412a43 | 1076 | |
9bc61ab1 | 1077 | put_fs_context(fc); |
8f291889 | 1078 | return mnt; |
9d412a43 AV |
1079 | } |
1080 | EXPORT_SYMBOL_GPL(vfs_kern_mount); | |
1081 | ||
93faccbb EB |
1082 | struct vfsmount * |
1083 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, | |
1084 | const char *name, void *data) | |
1085 | { | |
1086 | /* Until it is worked out how to pass the user namespace | |
1087 | * through from the parent mount to the submount don't support | |
1088 | * unprivileged mounts with submounts. | |
1089 | */ | |
1090 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) | |
1091 | return ERR_PTR(-EPERM); | |
1092 | ||
e462ec50 | 1093 | return vfs_kern_mount(type, SB_SUBMOUNT, name, data); |
93faccbb EB |
1094 | } |
1095 | EXPORT_SYMBOL_GPL(vfs_submount); | |
1096 | ||
87129cc0 | 1097 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
36341f64 | 1098 | int flag) |
1da177e4 | 1099 | { |
87129cc0 | 1100 | struct super_block *sb = old->mnt.mnt_sb; |
be34d1a3 DH |
1101 | struct mount *mnt; |
1102 | int err; | |
1da177e4 | 1103 | |
be34d1a3 DH |
1104 | mnt = alloc_vfsmnt(old->mnt_devname); |
1105 | if (!mnt) | |
1106 | return ERR_PTR(-ENOMEM); | |
719f5d7f | 1107 | |
7a472ef4 | 1108 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
be34d1a3 DH |
1109 | mnt->mnt_group_id = 0; /* not a peer of original */ |
1110 | else | |
1111 | mnt->mnt_group_id = old->mnt_group_id; | |
b90fa9ae | 1112 | |
be34d1a3 DH |
1113 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
1114 | err = mnt_alloc_group_id(mnt); | |
1115 | if (err) | |
1116 | goto out_free; | |
1da177e4 | 1117 | } |
be34d1a3 | 1118 | |
16a34adb AV |
1119 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
1120 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); | |
5ff9d8a6 | 1121 | |
be34d1a3 | 1122 | atomic_inc(&sb->s_active); |
a6435940 | 1123 | mnt->mnt.mnt_userns = mnt_user_ns(&old->mnt); |
bd303368 | 1124 | if (!initial_idmapping(mnt->mnt.mnt_userns)) |
a6435940 | 1125 | mnt->mnt.mnt_userns = get_user_ns(mnt->mnt.mnt_userns); |
be34d1a3 DH |
1126 | mnt->mnt.mnt_sb = sb; |
1127 | mnt->mnt.mnt_root = dget(root); | |
1128 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; | |
1129 | mnt->mnt_parent = mnt; | |
719ea2fb | 1130 | lock_mount_hash(); |
be34d1a3 | 1131 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
719ea2fb | 1132 | unlock_mount_hash(); |
be34d1a3 | 1133 | |
7a472ef4 EB |
1134 | if ((flag & CL_SLAVE) || |
1135 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { | |
be34d1a3 DH |
1136 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
1137 | mnt->mnt_master = old; | |
1138 | CLEAR_MNT_SHARED(mnt); | |
1139 | } else if (!(flag & CL_PRIVATE)) { | |
1140 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) | |
1141 | list_add(&mnt->mnt_share, &old->mnt_share); | |
1142 | if (IS_MNT_SLAVE(old)) | |
1143 | list_add(&mnt->mnt_slave, &old->mnt_slave); | |
1144 | mnt->mnt_master = old->mnt_master; | |
5235d448 AV |
1145 | } else { |
1146 | CLEAR_MNT_SHARED(mnt); | |
be34d1a3 DH |
1147 | } |
1148 | if (flag & CL_MAKE_SHARED) | |
1149 | set_mnt_shared(mnt); | |
1150 | ||
1151 | /* stick the duplicate mount on the same expiry list | |
1152 | * as the original if that was on one */ | |
1153 | if (flag & CL_EXPIRE) { | |
1154 | if (!list_empty(&old->mnt_expire)) | |
1155 | list_add(&mnt->mnt_expire, &old->mnt_expire); | |
1156 | } | |
1157 | ||
cb338d06 | 1158 | return mnt; |
719f5d7f MS |
1159 | |
1160 | out_free: | |
8ffcb32e | 1161 | mnt_free_id(mnt); |
719f5d7f | 1162 | free_vfsmnt(mnt); |
be34d1a3 | 1163 | return ERR_PTR(err); |
1da177e4 LT |
1164 | } |
1165 | ||
9ea459e1 AV |
1166 | static void cleanup_mnt(struct mount *mnt) |
1167 | { | |
56cbb429 AV |
1168 | struct hlist_node *p; |
1169 | struct mount *m; | |
9ea459e1 | 1170 | /* |
56cbb429 AV |
1171 | * The warning here probably indicates that somebody messed |
1172 | * up a mnt_want/drop_write() pair. If this happens, the | |
1173 | * filesystem was probably unable to make r/w->r/o transitions. | |
9ea459e1 AV |
1174 | * The locking used to deal with mnt_count decrement provides barriers, |
1175 | * so mnt_get_writers() below is safe. | |
1176 | */ | |
1177 | WARN_ON(mnt_get_writers(mnt)); | |
1178 | if (unlikely(mnt->mnt_pins.first)) | |
1179 | mnt_pin_kill(mnt); | |
56cbb429 AV |
1180 | hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) { |
1181 | hlist_del(&m->mnt_umount); | |
1182 | mntput(&m->mnt); | |
1183 | } | |
9ea459e1 AV |
1184 | fsnotify_vfsmount_delete(&mnt->mnt); |
1185 | dput(mnt->mnt.mnt_root); | |
1186 | deactivate_super(mnt->mnt.mnt_sb); | |
1187 | mnt_free_id(mnt); | |
1188 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); | |
1189 | } | |
1190 | ||
1191 | static void __cleanup_mnt(struct rcu_head *head) | |
1192 | { | |
1193 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); | |
1194 | } | |
1195 | ||
1196 | static LLIST_HEAD(delayed_mntput_list); | |
1197 | static void delayed_mntput(struct work_struct *unused) | |
1198 | { | |
1199 | struct llist_node *node = llist_del_all(&delayed_mntput_list); | |
29785735 | 1200 | struct mount *m, *t; |
9ea459e1 | 1201 | |
29785735 BP |
1202 | llist_for_each_entry_safe(m, t, node, mnt_llist) |
1203 | cleanup_mnt(m); | |
9ea459e1 AV |
1204 | } |
1205 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); | |
1206 | ||
900148dc | 1207 | static void mntput_no_expire(struct mount *mnt) |
b3e19d92 | 1208 | { |
4edbe133 | 1209 | LIST_HEAD(list); |
edf7ddbf | 1210 | int count; |
4edbe133 | 1211 | |
48a066e7 | 1212 | rcu_read_lock(); |
9ea0a46c AV |
1213 | if (likely(READ_ONCE(mnt->mnt_ns))) { |
1214 | /* | |
1215 | * Since we don't do lock_mount_hash() here, | |
1216 | * ->mnt_ns can change under us. However, if it's | |
1217 | * non-NULL, then there's a reference that won't | |
1218 | * be dropped until after an RCU delay done after | |
1219 | * turning ->mnt_ns NULL. So if we observe it | |
1220 | * non-NULL under rcu_read_lock(), the reference | |
1221 | * we are dropping is not the final one. | |
1222 | */ | |
1223 | mnt_add_count(mnt, -1); | |
48a066e7 | 1224 | rcu_read_unlock(); |
f03c6599 | 1225 | return; |
b3e19d92 | 1226 | } |
719ea2fb | 1227 | lock_mount_hash(); |
119e1ef8 AV |
1228 | /* |
1229 | * make sure that if __legitimize_mnt() has not seen us grab | |
1230 | * mount_lock, we'll see their refcount increment here. | |
1231 | */ | |
1232 | smp_mb(); | |
9ea0a46c | 1233 | mnt_add_count(mnt, -1); |
edf7ddbf EB |
1234 | count = mnt_get_count(mnt); |
1235 | if (count != 0) { | |
1236 | WARN_ON(count < 0); | |
48a066e7 | 1237 | rcu_read_unlock(); |
719ea2fb | 1238 | unlock_mount_hash(); |
99b7db7b NP |
1239 | return; |
1240 | } | |
48a066e7 AV |
1241 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
1242 | rcu_read_unlock(); | |
1243 | unlock_mount_hash(); | |
1244 | return; | |
1245 | } | |
1246 | mnt->mnt.mnt_flags |= MNT_DOOMED; | |
1247 | rcu_read_unlock(); | |
962830df | 1248 | |
39f7c4db | 1249 | list_del(&mnt->mnt_instance); |
ce07d891 EB |
1250 | |
1251 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { | |
1252 | struct mount *p, *tmp; | |
1253 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { | |
4edbe133 | 1254 | __put_mountpoint(unhash_mnt(p), &list); |
56cbb429 | 1255 | hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children); |
ce07d891 EB |
1256 | } |
1257 | } | |
719ea2fb | 1258 | unlock_mount_hash(); |
4edbe133 | 1259 | shrink_dentry_list(&list); |
649a795a | 1260 | |
9ea459e1 AV |
1261 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
1262 | struct task_struct *task = current; | |
1263 | if (likely(!(task->flags & PF_KTHREAD))) { | |
1264 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); | |
91989c70 | 1265 | if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME)) |
9ea459e1 AV |
1266 | return; |
1267 | } | |
1268 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) | |
1269 | schedule_delayed_work(&delayed_mntput_work, 1); | |
1270 | return; | |
1271 | } | |
1272 | cleanup_mnt(mnt); | |
b3e19d92 | 1273 | } |
b3e19d92 NP |
1274 | |
1275 | void mntput(struct vfsmount *mnt) | |
1276 | { | |
1277 | if (mnt) { | |
863d684f | 1278 | struct mount *m = real_mount(mnt); |
b3e19d92 | 1279 | /* avoid cacheline pingpong, hope gcc doesn't get "smart" */ |
863d684f AV |
1280 | if (unlikely(m->mnt_expiry_mark)) |
1281 | m->mnt_expiry_mark = 0; | |
1282 | mntput_no_expire(m); | |
b3e19d92 NP |
1283 | } |
1284 | } | |
1285 | EXPORT_SYMBOL(mntput); | |
1286 | ||
1287 | struct vfsmount *mntget(struct vfsmount *mnt) | |
1288 | { | |
1289 | if (mnt) | |
83adc753 | 1290 | mnt_add_count(real_mount(mnt), 1); |
b3e19d92 NP |
1291 | return mnt; |
1292 | } | |
1293 | EXPORT_SYMBOL(mntget); | |
1294 | ||
1f287bc4 RD |
1295 | /** |
1296 | * path_is_mountpoint() - Check if path is a mount in the current namespace. | |
1297 | * @path: path to check | |
c6609c0a IK |
1298 | * |
1299 | * d_mountpoint() can only be used reliably to establish if a dentry is | |
1300 | * not mounted in any namespace and that common case is handled inline. | |
1301 | * d_mountpoint() isn't aware of the possibility there may be multiple | |
1302 | * mounts using a given dentry in a different namespace. This function | |
1303 | * checks if the passed in path is a mountpoint rather than the dentry | |
1304 | * alone. | |
1305 | */ | |
1306 | bool path_is_mountpoint(const struct path *path) | |
1307 | { | |
1308 | unsigned seq; | |
1309 | bool res; | |
1310 | ||
1311 | if (!d_mountpoint(path->dentry)) | |
1312 | return false; | |
1313 | ||
1314 | rcu_read_lock(); | |
1315 | do { | |
1316 | seq = read_seqbegin(&mount_lock); | |
1317 | res = __path_is_mountpoint(path); | |
1318 | } while (read_seqretry(&mount_lock, seq)); | |
1319 | rcu_read_unlock(); | |
1320 | ||
1321 | return res; | |
1322 | } | |
1323 | EXPORT_SYMBOL(path_is_mountpoint); | |
1324 | ||
ca71cf71 | 1325 | struct vfsmount *mnt_clone_internal(const struct path *path) |
7b7b1ace | 1326 | { |
3064c356 AV |
1327 | struct mount *p; |
1328 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); | |
1329 | if (IS_ERR(p)) | |
1330 | return ERR_CAST(p); | |
1331 | p->mnt.mnt_flags |= MNT_INTERNAL; | |
1332 | return &p->mnt; | |
7b7b1ace | 1333 | } |
1da177e4 | 1334 | |
a1a2c409 | 1335 | #ifdef CONFIG_PROC_FS |
9f6c61f9 MS |
1336 | static struct mount *mnt_list_next(struct mnt_namespace *ns, |
1337 | struct list_head *p) | |
1338 | { | |
1339 | struct mount *mnt, *ret = NULL; | |
1340 | ||
1341 | lock_ns_list(ns); | |
1342 | list_for_each_continue(p, &ns->list) { | |
1343 | mnt = list_entry(p, typeof(*mnt), mnt_list); | |
1344 | if (!mnt_is_cursor(mnt)) { | |
1345 | ret = mnt; | |
1346 | break; | |
1347 | } | |
1348 | } | |
1349 | unlock_ns_list(ns); | |
1350 | ||
1351 | return ret; | |
1352 | } | |
1353 | ||
0226f492 | 1354 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
1da177e4 LT |
1355 | static void *m_start(struct seq_file *m, loff_t *pos) |
1356 | { | |
ede1bf0d | 1357 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1358 | struct list_head *prev; |
1da177e4 | 1359 | |
390c6843 | 1360 | down_read(&namespace_sem); |
9f6c61f9 MS |
1361 | if (!*pos) { |
1362 | prev = &p->ns->list; | |
1363 | } else { | |
1364 | prev = &p->cursor.mnt_list; | |
1365 | ||
1366 | /* Read after we'd reached the end? */ | |
1367 | if (list_empty(prev)) | |
1368 | return NULL; | |
c7999c36 AV |
1369 | } |
1370 | ||
9f6c61f9 | 1371 | return mnt_list_next(p->ns, prev); |
1da177e4 LT |
1372 | } |
1373 | ||
1374 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) | |
1375 | { | |
ede1bf0d | 1376 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1377 | struct mount *mnt = v; |
b0765fb8 | 1378 | |
9f6c61f9 MS |
1379 | ++*pos; |
1380 | return mnt_list_next(p->ns, &mnt->mnt_list); | |
1da177e4 LT |
1381 | } |
1382 | ||
1383 | static void m_stop(struct seq_file *m, void *v) | |
1384 | { | |
9f6c61f9 MS |
1385 | struct proc_mounts *p = m->private; |
1386 | struct mount *mnt = v; | |
1387 | ||
1388 | lock_ns_list(p->ns); | |
1389 | if (mnt) | |
1390 | list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); | |
1391 | else | |
1392 | list_del_init(&p->cursor.mnt_list); | |
1393 | unlock_ns_list(p->ns); | |
390c6843 | 1394 | up_read(&namespace_sem); |
1da177e4 LT |
1395 | } |
1396 | ||
0226f492 | 1397 | static int m_show(struct seq_file *m, void *v) |
2d4d4864 | 1398 | { |
ede1bf0d | 1399 | struct proc_mounts *p = m->private; |
9f6c61f9 | 1400 | struct mount *r = v; |
0226f492 | 1401 | return p->show(m, &r->mnt); |
1da177e4 LT |
1402 | } |
1403 | ||
a1a2c409 | 1404 | const struct seq_operations mounts_op = { |
1da177e4 LT |
1405 | .start = m_start, |
1406 | .next = m_next, | |
1407 | .stop = m_stop, | |
0226f492 | 1408 | .show = m_show, |
b4629fe2 | 1409 | }; |
9f6c61f9 MS |
1410 | |
1411 | void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) | |
1412 | { | |
1413 | down_read(&namespace_sem); | |
1414 | lock_ns_list(ns); | |
1415 | list_del(&cursor->mnt_list); | |
1416 | unlock_ns_list(ns); | |
1417 | up_read(&namespace_sem); | |
1418 | } | |
a1a2c409 | 1419 | #endif /* CONFIG_PROC_FS */ |
b4629fe2 | 1420 | |
1da177e4 LT |
1421 | /** |
1422 | * may_umount_tree - check if a mount tree is busy | |
1f287bc4 | 1423 | * @m: root of mount tree |
1da177e4 LT |
1424 | * |
1425 | * This is called to check if a tree of mounts has any | |
1426 | * open files, pwds, chroots or sub mounts that are | |
1427 | * busy. | |
1428 | */ | |
909b0a88 | 1429 | int may_umount_tree(struct vfsmount *m) |
1da177e4 | 1430 | { |
909b0a88 | 1431 | struct mount *mnt = real_mount(m); |
36341f64 RP |
1432 | int actual_refs = 0; |
1433 | int minimum_refs = 0; | |
315fc83e | 1434 | struct mount *p; |
909b0a88 | 1435 | BUG_ON(!m); |
1da177e4 | 1436 | |
b3e19d92 | 1437 | /* write lock needed for mnt_get_count */ |
719ea2fb | 1438 | lock_mount_hash(); |
909b0a88 | 1439 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
83adc753 | 1440 | actual_refs += mnt_get_count(p); |
1da177e4 | 1441 | minimum_refs += 2; |
1da177e4 | 1442 | } |
719ea2fb | 1443 | unlock_mount_hash(); |
1da177e4 LT |
1444 | |
1445 | if (actual_refs > minimum_refs) | |
e3474a8e | 1446 | return 0; |
1da177e4 | 1447 | |
e3474a8e | 1448 | return 1; |
1da177e4 LT |
1449 | } |
1450 | ||
1451 | EXPORT_SYMBOL(may_umount_tree); | |
1452 | ||
1453 | /** | |
1454 | * may_umount - check if a mount point is busy | |
1455 | * @mnt: root of mount | |
1456 | * | |
1457 | * This is called to check if a mount point has any | |
1458 | * open files, pwds, chroots or sub mounts. If the | |
1459 | * mount has sub mounts this will return busy | |
1460 | * regardless of whether the sub mounts are busy. | |
1461 | * | |
1462 | * Doesn't take quota and stuff into account. IOW, in some cases it will | |
1463 | * give false negatives. The main reason why it's here is that we need | |
1464 | * a non-destructive way to look for easily umountable filesystems. | |
1465 | */ | |
1466 | int may_umount(struct vfsmount *mnt) | |
1467 | { | |
e3474a8e | 1468 | int ret = 1; |
8ad08d8a | 1469 | down_read(&namespace_sem); |
719ea2fb | 1470 | lock_mount_hash(); |
1ab59738 | 1471 | if (propagate_mount_busy(real_mount(mnt), 2)) |
e3474a8e | 1472 | ret = 0; |
719ea2fb | 1473 | unlock_mount_hash(); |
8ad08d8a | 1474 | up_read(&namespace_sem); |
a05964f3 | 1475 | return ret; |
1da177e4 LT |
1476 | } |
1477 | ||
1478 | EXPORT_SYMBOL(may_umount); | |
1479 | ||
97216be0 | 1480 | static void namespace_unlock(void) |
70fbcdf4 | 1481 | { |
a3b3c562 | 1482 | struct hlist_head head; |
56cbb429 AV |
1483 | struct hlist_node *p; |
1484 | struct mount *m; | |
4edbe133 | 1485 | LIST_HEAD(list); |
97216be0 | 1486 | |
a3b3c562 | 1487 | hlist_move_list(&unmounted, &head); |
4edbe133 | 1488 | list_splice_init(&ex_mountpoints, &list); |
97216be0 | 1489 | |
97216be0 AV |
1490 | up_write(&namespace_sem); |
1491 | ||
4edbe133 AV |
1492 | shrink_dentry_list(&list); |
1493 | ||
a3b3c562 EB |
1494 | if (likely(hlist_empty(&head))) |
1495 | return; | |
1496 | ||
22cb7405 | 1497 | synchronize_rcu_expedited(); |
48a066e7 | 1498 | |
56cbb429 AV |
1499 | hlist_for_each_entry_safe(m, p, &head, mnt_umount) { |
1500 | hlist_del(&m->mnt_umount); | |
1501 | mntput(&m->mnt); | |
1502 | } | |
70fbcdf4 RP |
1503 | } |
1504 | ||
97216be0 | 1505 | static inline void namespace_lock(void) |
e3197d83 | 1506 | { |
97216be0 | 1507 | down_write(&namespace_sem); |
e3197d83 AV |
1508 | } |
1509 | ||
e819f152 EB |
1510 | enum umount_tree_flags { |
1511 | UMOUNT_SYNC = 1, | |
1512 | UMOUNT_PROPAGATE = 2, | |
e0c9c0af | 1513 | UMOUNT_CONNECTED = 4, |
e819f152 | 1514 | }; |
f2d0a123 EB |
1515 | |
1516 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) | |
1517 | { | |
1518 | /* Leaving mounts connected is only valid for lazy umounts */ | |
1519 | if (how & UMOUNT_SYNC) | |
1520 | return true; | |
1521 | ||
1522 | /* A mount without a parent has nothing to be connected to */ | |
1523 | if (!mnt_has_parent(mnt)) | |
1524 | return true; | |
1525 | ||
1526 | /* Because the reference counting rules change when mounts are | |
1527 | * unmounted and connected, umounted mounts may not be | |
1528 | * connected to mounted mounts. | |
1529 | */ | |
1530 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) | |
1531 | return true; | |
1532 | ||
1533 | /* Has it been requested that the mount remain connected? */ | |
1534 | if (how & UMOUNT_CONNECTED) | |
1535 | return false; | |
1536 | ||
1537 | /* Is the mount locked such that it needs to remain connected? */ | |
1538 | if (IS_MNT_LOCKED(mnt)) | |
1539 | return false; | |
1540 | ||
1541 | /* By default disconnect the mount */ | |
1542 | return true; | |
1543 | } | |
1544 | ||
99b7db7b | 1545 | /* |
48a066e7 | 1546 | * mount_lock must be held |
99b7db7b NP |
1547 | * namespace_sem must be held for write |
1548 | */ | |
e819f152 | 1549 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
1da177e4 | 1550 | { |
c003b26f | 1551 | LIST_HEAD(tmp_list); |
315fc83e | 1552 | struct mount *p; |
1da177e4 | 1553 | |
5d88457e EB |
1554 | if (how & UMOUNT_PROPAGATE) |
1555 | propagate_mount_unlock(mnt); | |
1556 | ||
c003b26f | 1557 | /* Gather the mounts to umount */ |
590ce4bc EB |
1558 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
1559 | p->mnt.mnt_flags |= MNT_UMOUNT; | |
c003b26f | 1560 | list_move(&p->mnt_list, &tmp_list); |
590ce4bc | 1561 | } |
1da177e4 | 1562 | |
411a938b | 1563 | /* Hide the mounts from mnt_mounts */ |
c003b26f | 1564 | list_for_each_entry(p, &tmp_list, mnt_list) { |
88b368f2 | 1565 | list_del_init(&p->mnt_child); |
c003b26f | 1566 | } |
88b368f2 | 1567 | |
c003b26f | 1568 | /* Add propogated mounts to the tmp_list */ |
e819f152 | 1569 | if (how & UMOUNT_PROPAGATE) |
7b8a53fd | 1570 | propagate_umount(&tmp_list); |
a05964f3 | 1571 | |
c003b26f | 1572 | while (!list_empty(&tmp_list)) { |
d2921684 | 1573 | struct mnt_namespace *ns; |
ce07d891 | 1574 | bool disconnect; |
c003b26f | 1575 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
6776db3d | 1576 | list_del_init(&p->mnt_expire); |
1a4eeaf2 | 1577 | list_del_init(&p->mnt_list); |
d2921684 EB |
1578 | ns = p->mnt_ns; |
1579 | if (ns) { | |
1580 | ns->mounts--; | |
1581 | __touch_mnt_namespace(ns); | |
1582 | } | |
143c8c91 | 1583 | p->mnt_ns = NULL; |
e819f152 | 1584 | if (how & UMOUNT_SYNC) |
48a066e7 | 1585 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
87b95ce0 | 1586 | |
f2d0a123 | 1587 | disconnect = disconnect_mount(p, how); |
676da58d | 1588 | if (mnt_has_parent(p)) { |
81b6b061 | 1589 | mnt_add_count(p->mnt_parent, -1); |
ce07d891 EB |
1590 | if (!disconnect) { |
1591 | /* Don't forget about p */ | |
1592 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); | |
1593 | } else { | |
1594 | umount_mnt(p); | |
1595 | } | |
7c4b93d8 | 1596 | } |
0f0afb1d | 1597 | change_mnt_propagation(p, MS_PRIVATE); |
19a1c409 AV |
1598 | if (disconnect) |
1599 | hlist_add_head(&p->mnt_umount, &unmounted); | |
1da177e4 LT |
1600 | } |
1601 | } | |
1602 | ||
b54b9be7 | 1603 | static void shrink_submounts(struct mount *mnt); |
c35038be | 1604 | |
8d0347f6 DH |
1605 | static int do_umount_root(struct super_block *sb) |
1606 | { | |
1607 | int ret = 0; | |
1608 | ||
1609 | down_write(&sb->s_umount); | |
1610 | if (!sb_rdonly(sb)) { | |
1611 | struct fs_context *fc; | |
1612 | ||
1613 | fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY, | |
1614 | SB_RDONLY); | |
1615 | if (IS_ERR(fc)) { | |
1616 | ret = PTR_ERR(fc); | |
1617 | } else { | |
1618 | ret = parse_monolithic_mount_data(fc, NULL); | |
1619 | if (!ret) | |
1620 | ret = reconfigure_super(fc); | |
1621 | put_fs_context(fc); | |
1622 | } | |
1623 | } | |
1624 | up_write(&sb->s_umount); | |
1625 | return ret; | |
1626 | } | |
1627 | ||
1ab59738 | 1628 | static int do_umount(struct mount *mnt, int flags) |
1da177e4 | 1629 | { |
1ab59738 | 1630 | struct super_block *sb = mnt->mnt.mnt_sb; |
1da177e4 LT |
1631 | int retval; |
1632 | ||
1ab59738 | 1633 | retval = security_sb_umount(&mnt->mnt, flags); |
1da177e4 LT |
1634 | if (retval) |
1635 | return retval; | |
1636 | ||
1637 | /* | |
1638 | * Allow userspace to request a mountpoint be expired rather than | |
1639 | * unmounting unconditionally. Unmount only happens if: | |
1640 | * (1) the mark is already set (the mark is cleared by mntput()) | |
1641 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] | |
1642 | */ | |
1643 | if (flags & MNT_EXPIRE) { | |
1ab59738 | 1644 | if (&mnt->mnt == current->fs->root.mnt || |
1da177e4 LT |
1645 | flags & (MNT_FORCE | MNT_DETACH)) |
1646 | return -EINVAL; | |
1647 | ||
b3e19d92 NP |
1648 | /* |
1649 | * probably don't strictly need the lock here if we examined | |
1650 | * all race cases, but it's a slowpath. | |
1651 | */ | |
719ea2fb | 1652 | lock_mount_hash(); |
83adc753 | 1653 | if (mnt_get_count(mnt) != 2) { |
719ea2fb | 1654 | unlock_mount_hash(); |
1da177e4 | 1655 | return -EBUSY; |
b3e19d92 | 1656 | } |
719ea2fb | 1657 | unlock_mount_hash(); |
1da177e4 | 1658 | |
863d684f | 1659 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
1da177e4 LT |
1660 | return -EAGAIN; |
1661 | } | |
1662 | ||
1663 | /* | |
1664 | * If we may have to abort operations to get out of this | |
1665 | * mount, and they will themselves hold resources we must | |
1666 | * allow the fs to do things. In the Unix tradition of | |
1667 | * 'Gee thats tricky lets do it in userspace' the umount_begin | |
1668 | * might fail to complete on the first run through as other tasks | |
1669 | * must return, and the like. Thats for the mount program to worry | |
1670 | * about for the moment. | |
1671 | */ | |
1672 | ||
42faad99 | 1673 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
42faad99 | 1674 | sb->s_op->umount_begin(sb); |
42faad99 | 1675 | } |
1da177e4 LT |
1676 | |
1677 | /* | |
1678 | * No sense to grab the lock for this test, but test itself looks | |
1679 | * somewhat bogus. Suggestions for better replacement? | |
1680 | * Ho-hum... In principle, we might treat that as umount + switch | |
1681 | * to rootfs. GC would eventually take care of the old vfsmount. | |
1682 | * Actually it makes sense, especially if rootfs would contain a | |
1683 | * /reboot - static binary that would close all descriptors and | |
1684 | * call reboot(9). Then init(8) could umount root and exec /reboot. | |
1685 | */ | |
1ab59738 | 1686 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
1da177e4 LT |
1687 | /* |
1688 | * Special case for "unmounting" root ... | |
1689 | * we just try to remount it readonly. | |
1690 | */ | |
bc6155d1 | 1691 | if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) |
a1480dcc | 1692 | return -EPERM; |
8d0347f6 | 1693 | return do_umount_root(sb); |
1da177e4 LT |
1694 | } |
1695 | ||
97216be0 | 1696 | namespace_lock(); |
719ea2fb | 1697 | lock_mount_hash(); |
1da177e4 | 1698 | |
25d202ed EB |
1699 | /* Recheck MNT_LOCKED with the locks held */ |
1700 | retval = -EINVAL; | |
1701 | if (mnt->mnt.mnt_flags & MNT_LOCKED) | |
1702 | goto out; | |
1703 | ||
1704 | event++; | |
48a066e7 | 1705 | if (flags & MNT_DETACH) { |
1a4eeaf2 | 1706 | if (!list_empty(&mnt->mnt_list)) |
e819f152 | 1707 | umount_tree(mnt, UMOUNT_PROPAGATE); |
1da177e4 | 1708 | retval = 0; |
48a066e7 AV |
1709 | } else { |
1710 | shrink_submounts(mnt); | |
1711 | retval = -EBUSY; | |
1712 | if (!propagate_mount_busy(mnt, 2)) { | |
1713 | if (!list_empty(&mnt->mnt_list)) | |
e819f152 | 1714 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
48a066e7 AV |
1715 | retval = 0; |
1716 | } | |
1da177e4 | 1717 | } |
25d202ed | 1718 | out: |
719ea2fb | 1719 | unlock_mount_hash(); |
e3197d83 | 1720 | namespace_unlock(); |
1da177e4 LT |
1721 | return retval; |
1722 | } | |
1723 | ||
80b5dce8 EB |
1724 | /* |
1725 | * __detach_mounts - lazily unmount all mounts on the specified dentry | |
1726 | * | |
1727 | * During unlink, rmdir, and d_drop it is possible to loose the path | |
1728 | * to an existing mountpoint, and wind up leaking the mount. | |
1729 | * detach_mounts allows lazily unmounting those mounts instead of | |
1730 | * leaking them. | |
1731 | * | |
1732 | * The caller may hold dentry->d_inode->i_mutex. | |
1733 | */ | |
1734 | void __detach_mounts(struct dentry *dentry) | |
1735 | { | |
1736 | struct mountpoint *mp; | |
1737 | struct mount *mnt; | |
1738 | ||
1739 | namespace_lock(); | |
3895dbf8 | 1740 | lock_mount_hash(); |
80b5dce8 | 1741 | mp = lookup_mountpoint(dentry); |
adc9b5c0 | 1742 | if (!mp) |
80b5dce8 EB |
1743 | goto out_unlock; |
1744 | ||
e06b933e | 1745 | event++; |
80b5dce8 EB |
1746 | while (!hlist_empty(&mp->m_list)) { |
1747 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); | |
ce07d891 | 1748 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
fe78fcc8 | 1749 | umount_mnt(mnt); |
56cbb429 | 1750 | hlist_add_head(&mnt->mnt_umount, &unmounted); |
ce07d891 | 1751 | } |
e0c9c0af | 1752 | else umount_tree(mnt, UMOUNT_CONNECTED); |
80b5dce8 | 1753 | } |
80b5dce8 EB |
1754 | put_mountpoint(mp); |
1755 | out_unlock: | |
3895dbf8 | 1756 | unlock_mount_hash(); |
80b5dce8 EB |
1757 | namespace_unlock(); |
1758 | } | |
1759 | ||
dd111b31 | 1760 | /* |
9b40bc90 AV |
1761 | * Is the caller allowed to modify his namespace? |
1762 | */ | |
a5f85d78 | 1763 | bool may_mount(void) |
9b40bc90 AV |
1764 | { |
1765 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); | |
1766 | } | |
1767 | ||
f7e33bdb | 1768 | static void warn_mandlock(void) |
9e8925b6 | 1769 | { |
f7e33bdb JL |
1770 | pr_warn_once("=======================================================\n" |
1771 | "WARNING: The mand mount option has been deprecated and\n" | |
1772 | " and is ignored by this kernel. Remove the mand\n" | |
1773 | " option from the mount to silence this warning.\n" | |
1774 | "=======================================================\n"); | |
9e8925b6 JL |
1775 | } |
1776 | ||
25ccd24f | 1777 | static int can_umount(const struct path *path, int flags) |
1da177e4 | 1778 | { |
25ccd24f | 1779 | struct mount *mnt = real_mount(path->mnt); |
1da177e4 | 1780 | |
9b40bc90 AV |
1781 | if (!may_mount()) |
1782 | return -EPERM; | |
41525f56 | 1783 | if (path->dentry != path->mnt->mnt_root) |
25ccd24f | 1784 | return -EINVAL; |
143c8c91 | 1785 | if (!check_mnt(mnt)) |
25ccd24f | 1786 | return -EINVAL; |
25d202ed | 1787 | if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ |
25ccd24f | 1788 | return -EINVAL; |
b2f5d4dc | 1789 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
25ccd24f CH |
1790 | return -EPERM; |
1791 | return 0; | |
1792 | } | |
1793 | ||
a0a6df9a | 1794 | // caller is responsible for flags being sane |
25ccd24f CH |
1795 | int path_umount(struct path *path, int flags) |
1796 | { | |
1797 | struct mount *mnt = real_mount(path->mnt); | |
1798 | int ret; | |
1799 | ||
1800 | ret = can_umount(path, flags); | |
1801 | if (!ret) | |
1802 | ret = do_umount(mnt, flags); | |
1da177e4 | 1803 | |
429731b1 | 1804 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
41525f56 | 1805 | dput(path->dentry); |
900148dc | 1806 | mntput_no_expire(mnt); |
25ccd24f | 1807 | return ret; |
1da177e4 LT |
1808 | } |
1809 | ||
09267def | 1810 | static int ksys_umount(char __user *name, int flags) |
41525f56 CH |
1811 | { |
1812 | int lookup_flags = LOOKUP_MOUNTPOINT; | |
1813 | struct path path; | |
1814 | int ret; | |
1815 | ||
a0a6df9a AV |
1816 | // basic validity checks done first |
1817 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) | |
1818 | return -EINVAL; | |
1819 | ||
41525f56 CH |
1820 | if (!(flags & UMOUNT_NOFOLLOW)) |
1821 | lookup_flags |= LOOKUP_FOLLOW; | |
1822 | ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); | |
1823 | if (ret) | |
1824 | return ret; | |
1825 | return path_umount(&path, flags); | |
1826 | } | |
1827 | ||
3a18ef5c DB |
1828 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
1829 | { | |
1830 | return ksys_umount(name, flags); | |
1831 | } | |
1832 | ||
1da177e4 LT |
1833 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
1834 | ||
1835 | /* | |
b58fed8b | 1836 | * The 2.0 compatible umount. No flags. |
1da177e4 | 1837 | */ |
bdc480e3 | 1838 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
1da177e4 | 1839 | { |
3a18ef5c | 1840 | return ksys_umount(name, 0); |
1da177e4 LT |
1841 | } |
1842 | ||
1843 | #endif | |
1844 | ||
4ce5d2b1 | 1845 | static bool is_mnt_ns_file(struct dentry *dentry) |
8823c079 | 1846 | { |
4ce5d2b1 | 1847 | /* Is this a proxy for a mount namespace? */ |
e149ed2b AV |
1848 | return dentry->d_op == &ns_dentry_operations && |
1849 | dentry->d_fsdata == &mntns_operations; | |
4ce5d2b1 EB |
1850 | } |
1851 | ||
213921f9 | 1852 | static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
58be2825 AV |
1853 | { |
1854 | return container_of(ns, struct mnt_namespace, ns); | |
1855 | } | |
1856 | ||
303cc571 CB |
1857 | struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) |
1858 | { | |
1859 | return &mnt->ns; | |
1860 | } | |
1861 | ||
4ce5d2b1 EB |
1862 | static bool mnt_ns_loop(struct dentry *dentry) |
1863 | { | |
1864 | /* Could bind mounting the mount namespace inode cause a | |
1865 | * mount namespace loop? | |
1866 | */ | |
1867 | struct mnt_namespace *mnt_ns; | |
1868 | if (!is_mnt_ns_file(dentry)) | |
1869 | return false; | |
1870 | ||
f77c8014 | 1871 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
8823c079 EB |
1872 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
1873 | } | |
1874 | ||
87129cc0 | 1875 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
36341f64 | 1876 | int flag) |
1da177e4 | 1877 | { |
84d17192 | 1878 | struct mount *res, *p, *q, *r, *parent; |
1da177e4 | 1879 | |
4ce5d2b1 EB |
1880 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
1881 | return ERR_PTR(-EINVAL); | |
1882 | ||
1883 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) | |
be34d1a3 | 1884 | return ERR_PTR(-EINVAL); |
9676f0c6 | 1885 | |
36341f64 | 1886 | res = q = clone_mnt(mnt, dentry, flag); |
be34d1a3 DH |
1887 | if (IS_ERR(q)) |
1888 | return q; | |
1889 | ||
a73324da | 1890 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
1da177e4 LT |
1891 | |
1892 | p = mnt; | |
6b41d536 | 1893 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
315fc83e | 1894 | struct mount *s; |
7ec02ef1 | 1895 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
1da177e4 LT |
1896 | continue; |
1897 | ||
909b0a88 | 1898 | for (s = r; s; s = next_mnt(s, r)) { |
4ce5d2b1 EB |
1899 | if (!(flag & CL_COPY_UNBINDABLE) && |
1900 | IS_MNT_UNBINDABLE(s)) { | |
df7342b2 EB |
1901 | if (s->mnt.mnt_flags & MNT_LOCKED) { |
1902 | /* Both unbindable and locked. */ | |
1903 | q = ERR_PTR(-EPERM); | |
1904 | goto out; | |
1905 | } else { | |
1906 | s = skip_mnt_tree(s); | |
1907 | continue; | |
1908 | } | |
4ce5d2b1 EB |
1909 | } |
1910 | if (!(flag & CL_COPY_MNT_NS_FILE) && | |
1911 | is_mnt_ns_file(s->mnt.mnt_root)) { | |
9676f0c6 RP |
1912 | s = skip_mnt_tree(s); |
1913 | continue; | |
1914 | } | |
0714a533 AV |
1915 | while (p != s->mnt_parent) { |
1916 | p = p->mnt_parent; | |
1917 | q = q->mnt_parent; | |
1da177e4 | 1918 | } |
87129cc0 | 1919 | p = s; |
84d17192 | 1920 | parent = q; |
87129cc0 | 1921 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
be34d1a3 DH |
1922 | if (IS_ERR(q)) |
1923 | goto out; | |
719ea2fb | 1924 | lock_mount_hash(); |
1a4eeaf2 | 1925 | list_add_tail(&q->mnt_list, &res->mnt_list); |
1064f874 | 1926 | attach_mnt(q, parent, p->mnt_mp); |
719ea2fb | 1927 | unlock_mount_hash(); |
1da177e4 LT |
1928 | } |
1929 | } | |
1930 | return res; | |
be34d1a3 | 1931 | out: |
1da177e4 | 1932 | if (res) { |
719ea2fb | 1933 | lock_mount_hash(); |
e819f152 | 1934 | umount_tree(res, UMOUNT_SYNC); |
719ea2fb | 1935 | unlock_mount_hash(); |
1da177e4 | 1936 | } |
be34d1a3 | 1937 | return q; |
1da177e4 LT |
1938 | } |
1939 | ||
be34d1a3 DH |
1940 | /* Caller should check returned pointer for errors */ |
1941 | ||
ca71cf71 | 1942 | struct vfsmount *collect_mounts(const struct path *path) |
8aec0809 | 1943 | { |
cb338d06 | 1944 | struct mount *tree; |
97216be0 | 1945 | namespace_lock(); |
cd4a4017 EB |
1946 | if (!check_mnt(real_mount(path->mnt))) |
1947 | tree = ERR_PTR(-EINVAL); | |
1948 | else | |
1949 | tree = copy_tree(real_mount(path->mnt), path->dentry, | |
1950 | CL_COPY_ALL | CL_PRIVATE); | |
328e6d90 | 1951 | namespace_unlock(); |
be34d1a3 | 1952 | if (IS_ERR(tree)) |
52e220d3 | 1953 | return ERR_CAST(tree); |
be34d1a3 | 1954 | return &tree->mnt; |
8aec0809 AV |
1955 | } |
1956 | ||
a07b2000 AV |
1957 | static void free_mnt_ns(struct mnt_namespace *); |
1958 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool); | |
1959 | ||
1960 | void dissolve_on_fput(struct vfsmount *mnt) | |
1961 | { | |
1962 | struct mnt_namespace *ns; | |
1963 | namespace_lock(); | |
1964 | lock_mount_hash(); | |
1965 | ns = real_mount(mnt)->mnt_ns; | |
44dfd84a DH |
1966 | if (ns) { |
1967 | if (is_anon_ns(ns)) | |
1968 | umount_tree(real_mount(mnt), UMOUNT_CONNECTED); | |
1969 | else | |
1970 | ns = NULL; | |
1971 | } | |
a07b2000 AV |
1972 | unlock_mount_hash(); |
1973 | namespace_unlock(); | |
44dfd84a DH |
1974 | if (ns) |
1975 | free_mnt_ns(ns); | |
a07b2000 AV |
1976 | } |
1977 | ||
8aec0809 AV |
1978 | void drop_collected_mounts(struct vfsmount *mnt) |
1979 | { | |
97216be0 | 1980 | namespace_lock(); |
719ea2fb | 1981 | lock_mount_hash(); |
9c8e0a1b | 1982 | umount_tree(real_mount(mnt), 0); |
719ea2fb | 1983 | unlock_mount_hash(); |
3ab6abee | 1984 | namespace_unlock(); |
8aec0809 AV |
1985 | } |
1986 | ||
427215d8 MS |
1987 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
1988 | { | |
1989 | struct mount *child; | |
1990 | ||
1991 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
1992 | if (!is_subdir(child->mnt_mountpoint, dentry)) | |
1993 | continue; | |
1994 | ||
1995 | if (child->mnt.mnt_flags & MNT_LOCKED) | |
1996 | return true; | |
1997 | } | |
1998 | return false; | |
1999 | } | |
2000 | ||
c771d683 MS |
2001 | /** |
2002 | * clone_private_mount - create a private clone of a path | |
1f287bc4 | 2003 | * @path: path to clone |
c771d683 | 2004 | * |
1f287bc4 RD |
2005 | * This creates a new vfsmount, which will be the clone of @path. The new mount |
2006 | * will not be attached anywhere in the namespace and will be private (i.e. | |
2007 | * changes to the originating mount won't be propagated into this). | |
c771d683 MS |
2008 | * |
2009 | * Release with mntput(). | |
2010 | */ | |
ca71cf71 | 2011 | struct vfsmount *clone_private_mount(const struct path *path) |
c771d683 MS |
2012 | { |
2013 | struct mount *old_mnt = real_mount(path->mnt); | |
2014 | struct mount *new_mnt; | |
2015 | ||
427215d8 | 2016 | down_read(&namespace_sem); |
c771d683 | 2017 | if (IS_MNT_UNBINDABLE(old_mnt)) |
427215d8 MS |
2018 | goto invalid; |
2019 | ||
2020 | if (!check_mnt(old_mnt)) | |
2021 | goto invalid; | |
2022 | ||
2023 | if (has_locked_children(old_mnt, path->dentry)) | |
2024 | goto invalid; | |
c771d683 | 2025 | |
c771d683 | 2026 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
427215d8 MS |
2027 | up_read(&namespace_sem); |
2028 | ||
c771d683 MS |
2029 | if (IS_ERR(new_mnt)) |
2030 | return ERR_CAST(new_mnt); | |
2031 | ||
df820f8d MS |
2032 | /* Longterm mount to be removed by kern_unmount*() */ |
2033 | new_mnt->mnt_ns = MNT_NS_INTERNAL; | |
2034 | ||
c771d683 | 2035 | return &new_mnt->mnt; |
427215d8 MS |
2036 | |
2037 | invalid: | |
2038 | up_read(&namespace_sem); | |
2039 | return ERR_PTR(-EINVAL); | |
c771d683 MS |
2040 | } |
2041 | EXPORT_SYMBOL_GPL(clone_private_mount); | |
2042 | ||
1f707137 AV |
2043 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
2044 | struct vfsmount *root) | |
2045 | { | |
1a4eeaf2 | 2046 | struct mount *mnt; |
1f707137 AV |
2047 | int res = f(root, arg); |
2048 | if (res) | |
2049 | return res; | |
1a4eeaf2 AV |
2050 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
2051 | res = f(&mnt->mnt, arg); | |
1f707137 AV |
2052 | if (res) |
2053 | return res; | |
2054 | } | |
2055 | return 0; | |
2056 | } | |
2057 | ||
3bd045cc AV |
2058 | static void lock_mnt_tree(struct mount *mnt) |
2059 | { | |
2060 | struct mount *p; | |
2061 | ||
2062 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
2063 | int flags = p->mnt.mnt_flags; | |
2064 | /* Don't allow unprivileged users to change mount flags */ | |
2065 | flags |= MNT_LOCK_ATIME; | |
2066 | ||
2067 | if (flags & MNT_READONLY) | |
2068 | flags |= MNT_LOCK_READONLY; | |
2069 | ||
2070 | if (flags & MNT_NODEV) | |
2071 | flags |= MNT_LOCK_NODEV; | |
2072 | ||
2073 | if (flags & MNT_NOSUID) | |
2074 | flags |= MNT_LOCK_NOSUID; | |
2075 | ||
2076 | if (flags & MNT_NOEXEC) | |
2077 | flags |= MNT_LOCK_NOEXEC; | |
2078 | /* Don't allow unprivileged users to reveal what is under a mount */ | |
2079 | if (list_empty(&p->mnt_expire)) | |
2080 | flags |= MNT_LOCKED; | |
2081 | p->mnt.mnt_flags = flags; | |
2082 | } | |
2083 | } | |
2084 | ||
4b8b21f4 | 2085 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
719f5d7f | 2086 | { |
315fc83e | 2087 | struct mount *p; |
719f5d7f | 2088 | |
909b0a88 | 2089 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
fc7be130 | 2090 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
4b8b21f4 | 2091 | mnt_release_group_id(p); |
719f5d7f MS |
2092 | } |
2093 | } | |
2094 | ||
4b8b21f4 | 2095 | static int invent_group_ids(struct mount *mnt, bool recurse) |
719f5d7f | 2096 | { |
315fc83e | 2097 | struct mount *p; |
719f5d7f | 2098 | |
909b0a88 | 2099 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
fc7be130 | 2100 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
4b8b21f4 | 2101 | int err = mnt_alloc_group_id(p); |
719f5d7f | 2102 | if (err) { |
4b8b21f4 | 2103 | cleanup_group_ids(mnt, p); |
719f5d7f MS |
2104 | return err; |
2105 | } | |
2106 | } | |
2107 | } | |
2108 | ||
2109 | return 0; | |
2110 | } | |
2111 | ||
d2921684 EB |
2112 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
2113 | { | |
2114 | unsigned int max = READ_ONCE(sysctl_mount_max); | |
124f75f8 | 2115 | unsigned int mounts = 0; |
d2921684 EB |
2116 | struct mount *p; |
2117 | ||
124f75f8 AV |
2118 | if (ns->mounts >= max) |
2119 | return -ENOSPC; | |
2120 | max -= ns->mounts; | |
2121 | if (ns->pending_mounts >= max) | |
2122 | return -ENOSPC; | |
2123 | max -= ns->pending_mounts; | |
2124 | ||
d2921684 EB |
2125 | for (p = mnt; p; p = next_mnt(p, mnt)) |
2126 | mounts++; | |
2127 | ||
124f75f8 | 2128 | if (mounts > max) |
d2921684 EB |
2129 | return -ENOSPC; |
2130 | ||
124f75f8 | 2131 | ns->pending_mounts += mounts; |
d2921684 EB |
2132 | return 0; |
2133 | } | |
2134 | ||
b90fa9ae RP |
2135 | /* |
2136 | * @source_mnt : mount tree to be attached | |
21444403 RP |
2137 | * @nd : place the mount tree @source_mnt is attached |
2138 | * @parent_nd : if non-null, detach the source_mnt from its parent and | |
2139 | * store the parent mount and mountpoint dentry. | |
2140 | * (done when source_mnt is moved) | |
b90fa9ae RP |
2141 | * |
2142 | * NOTE: in the table below explains the semantics when a source mount | |
2143 | * of a given type is attached to a destination mount of a given type. | |
9676f0c6 RP |
2144 | * --------------------------------------------------------------------------- |
2145 | * | BIND MOUNT OPERATION | | |
2146 | * |************************************************************************** | |
2147 | * | source-->| shared | private | slave | unbindable | | |
2148 | * | dest | | | | | | |
2149 | * | | | | | | | | |
2150 | * | v | | | | | | |
2151 | * |************************************************************************** | |
2152 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | | |
2153 | * | | | | | | | |
2154 | * |non-shared| shared (+) | private | slave (*) | invalid | | |
2155 | * *************************************************************************** | |
b90fa9ae RP |
2156 | * A bind operation clones the source mount and mounts the clone on the |
2157 | * destination mount. | |
2158 | * | |
2159 | * (++) the cloned mount is propagated to all the mounts in the propagation | |
2160 | * tree of the destination mount and the cloned mount is added to | |
2161 | * the peer group of the source mount. | |
2162 | * (+) the cloned mount is created under the destination mount and is marked | |
2163 | * as shared. The cloned mount is added to the peer group of the source | |
2164 | * mount. | |
5afe0022 RP |
2165 | * (+++) the mount is propagated to all the mounts in the propagation tree |
2166 | * of the destination mount and the cloned mount is made slave | |
2167 | * of the same master as that of the source mount. The cloned mount | |
2168 | * is marked as 'shared and slave'. | |
2169 | * (*) the cloned mount is made a slave of the same master as that of the | |
2170 | * source mount. | |
2171 | * | |
9676f0c6 RP |
2172 | * --------------------------------------------------------------------------- |
2173 | * | MOVE MOUNT OPERATION | | |
2174 | * |************************************************************************** | |
2175 | * | source-->| shared | private | slave | unbindable | | |
2176 | * | dest | | | | | | |
2177 | * | | | | | | | | |
2178 | * | v | | | | | | |
2179 | * |************************************************************************** | |
2180 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | | |
2181 | * | | | | | | | |
2182 | * |non-shared| shared (+*) | private | slave (*) | unbindable | | |
2183 | * *************************************************************************** | |
5afe0022 RP |
2184 | * |
2185 | * (+) the mount is moved to the destination. And is then propagated to | |
2186 | * all the mounts in the propagation tree of the destination mount. | |
21444403 | 2187 | * (+*) the mount is moved to the destination. |
5afe0022 RP |
2188 | * (+++) the mount is moved to the destination and is then propagated to |
2189 | * all the mounts belonging to the destination mount's propagation tree. | |
2190 | * the mount is marked as 'shared and slave'. | |
2191 | * (*) the mount continues to be a slave at the new location. | |
b90fa9ae RP |
2192 | * |
2193 | * if the source mount is a tree, the operations explained above is | |
2194 | * applied to each mount in the tree. | |
2195 | * Must be called without spinlocks held, since this function can sleep | |
2196 | * in allocations. | |
2197 | */ | |
0fb54e50 | 2198 | static int attach_recursive_mnt(struct mount *source_mnt, |
84d17192 AV |
2199 | struct mount *dest_mnt, |
2200 | struct mountpoint *dest_mp, | |
2763d119 | 2201 | bool moving) |
b90fa9ae | 2202 | { |
3bd045cc | 2203 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
38129a13 | 2204 | HLIST_HEAD(tree_list); |
d2921684 | 2205 | struct mnt_namespace *ns = dest_mnt->mnt_ns; |
1064f874 | 2206 | struct mountpoint *smp; |
315fc83e | 2207 | struct mount *child, *p; |
38129a13 | 2208 | struct hlist_node *n; |
719f5d7f | 2209 | int err; |
b90fa9ae | 2210 | |
1064f874 EB |
2211 | /* Preallocate a mountpoint in case the new mounts need |
2212 | * to be tucked under other mounts. | |
2213 | */ | |
2214 | smp = get_mountpoint(source_mnt->mnt.mnt_root); | |
2215 | if (IS_ERR(smp)) | |
2216 | return PTR_ERR(smp); | |
2217 | ||
d2921684 | 2218 | /* Is there space to add these mounts to the mount namespace? */ |
2763d119 | 2219 | if (!moving) { |
d2921684 EB |
2220 | err = count_mounts(ns, source_mnt); |
2221 | if (err) | |
2222 | goto out; | |
2223 | } | |
2224 | ||
fc7be130 | 2225 | if (IS_MNT_SHARED(dest_mnt)) { |
0fb54e50 | 2226 | err = invent_group_ids(source_mnt, true); |
719f5d7f MS |
2227 | if (err) |
2228 | goto out; | |
0b1b901b | 2229 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
f2ebb3a9 | 2230 | lock_mount_hash(); |
0b1b901b AV |
2231 | if (err) |
2232 | goto out_cleanup_ids; | |
909b0a88 | 2233 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
0f0afb1d | 2234 | set_mnt_shared(p); |
0b1b901b AV |
2235 | } else { |
2236 | lock_mount_hash(); | |
b90fa9ae | 2237 | } |
2763d119 AV |
2238 | if (moving) { |
2239 | unhash_mnt(source_mnt); | |
84d17192 | 2240 | attach_mnt(source_mnt, dest_mnt, dest_mp); |
143c8c91 | 2241 | touch_mnt_namespace(source_mnt->mnt_ns); |
21444403 | 2242 | } else { |
44dfd84a DH |
2243 | if (source_mnt->mnt_ns) { |
2244 | /* move from anon - the caller will destroy */ | |
2245 | list_del_init(&source_mnt->mnt_ns->list); | |
2246 | } | |
84d17192 | 2247 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
1064f874 | 2248 | commit_tree(source_mnt); |
21444403 | 2249 | } |
b90fa9ae | 2250 | |
38129a13 | 2251 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
1d6a32ac | 2252 | struct mount *q; |
38129a13 | 2253 | hlist_del_init(&child->mnt_hash); |
1064f874 EB |
2254 | q = __lookup_mnt(&child->mnt_parent->mnt, |
2255 | child->mnt_mountpoint); | |
2256 | if (q) | |
2257 | mnt_change_mountpoint(child, smp, q); | |
3bd045cc AV |
2258 | /* Notice when we are propagating across user namespaces */ |
2259 | if (child->mnt_parent->mnt_ns->user_ns != user_ns) | |
2260 | lock_mnt_tree(child); | |
d728cf79 | 2261 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
1064f874 | 2262 | commit_tree(child); |
b90fa9ae | 2263 | } |
1064f874 | 2264 | put_mountpoint(smp); |
719ea2fb | 2265 | unlock_mount_hash(); |
99b7db7b | 2266 | |
b90fa9ae | 2267 | return 0; |
719f5d7f MS |
2268 | |
2269 | out_cleanup_ids: | |
f2ebb3a9 AV |
2270 | while (!hlist_empty(&tree_list)) { |
2271 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); | |
d2921684 | 2272 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
e819f152 | 2273 | umount_tree(child, UMOUNT_SYNC); |
f2ebb3a9 AV |
2274 | } |
2275 | unlock_mount_hash(); | |
0b1b901b | 2276 | cleanup_group_ids(source_mnt, NULL); |
719f5d7f | 2277 | out: |
d2921684 | 2278 | ns->pending_mounts = 0; |
1064f874 EB |
2279 | |
2280 | read_seqlock_excl(&mount_lock); | |
2281 | put_mountpoint(smp); | |
2282 | read_sequnlock_excl(&mount_lock); | |
2283 | ||
719f5d7f | 2284 | return err; |
b90fa9ae RP |
2285 | } |
2286 | ||
84d17192 | 2287 | static struct mountpoint *lock_mount(struct path *path) |
b12cea91 AV |
2288 | { |
2289 | struct vfsmount *mnt; | |
84d17192 | 2290 | struct dentry *dentry = path->dentry; |
b12cea91 | 2291 | retry: |
5955102c | 2292 | inode_lock(dentry->d_inode); |
84d17192 | 2293 | if (unlikely(cant_mount(dentry))) { |
5955102c | 2294 | inode_unlock(dentry->d_inode); |
84d17192 | 2295 | return ERR_PTR(-ENOENT); |
b12cea91 | 2296 | } |
97216be0 | 2297 | namespace_lock(); |
b12cea91 | 2298 | mnt = lookup_mnt(path); |
84d17192 | 2299 | if (likely(!mnt)) { |
3895dbf8 | 2300 | struct mountpoint *mp = get_mountpoint(dentry); |
84d17192 | 2301 | if (IS_ERR(mp)) { |
97216be0 | 2302 | namespace_unlock(); |
5955102c | 2303 | inode_unlock(dentry->d_inode); |
84d17192 AV |
2304 | return mp; |
2305 | } | |
2306 | return mp; | |
2307 | } | |
97216be0 | 2308 | namespace_unlock(); |
5955102c | 2309 | inode_unlock(path->dentry->d_inode); |
b12cea91 AV |
2310 | path_put(path); |
2311 | path->mnt = mnt; | |
84d17192 | 2312 | dentry = path->dentry = dget(mnt->mnt_root); |
b12cea91 AV |
2313 | goto retry; |
2314 | } | |
2315 | ||
84d17192 | 2316 | static void unlock_mount(struct mountpoint *where) |
b12cea91 | 2317 | { |
84d17192 | 2318 | struct dentry *dentry = where->m_dentry; |
3895dbf8 EB |
2319 | |
2320 | read_seqlock_excl(&mount_lock); | |
84d17192 | 2321 | put_mountpoint(where); |
3895dbf8 EB |
2322 | read_sequnlock_excl(&mount_lock); |
2323 | ||
328e6d90 | 2324 | namespace_unlock(); |
5955102c | 2325 | inode_unlock(dentry->d_inode); |
b12cea91 AV |
2326 | } |
2327 | ||
84d17192 | 2328 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
1da177e4 | 2329 | { |
e462ec50 | 2330 | if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER) |
1da177e4 LT |
2331 | return -EINVAL; |
2332 | ||
e36cb0b8 DH |
2333 | if (d_is_dir(mp->m_dentry) != |
2334 | d_is_dir(mnt->mnt.mnt_root)) | |
1da177e4 LT |
2335 | return -ENOTDIR; |
2336 | ||
2763d119 | 2337 | return attach_recursive_mnt(mnt, p, mp, false); |
1da177e4 LT |
2338 | } |
2339 | ||
7a2e8a8f VA |
2340 | /* |
2341 | * Sanity check the flags to change_mnt_propagation. | |
2342 | */ | |
2343 | ||
e462ec50 | 2344 | static int flags_to_propagation_type(int ms_flags) |
7a2e8a8f | 2345 | { |
e462ec50 | 2346 | int type = ms_flags & ~(MS_REC | MS_SILENT); |
7a2e8a8f VA |
2347 | |
2348 | /* Fail if any non-propagation flags are set */ | |
2349 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
2350 | return 0; | |
2351 | /* Only one propagation flag should be set */ | |
2352 | if (!is_power_of_2(type)) | |
2353 | return 0; | |
2354 | return type; | |
2355 | } | |
2356 | ||
07b20889 RP |
2357 | /* |
2358 | * recursively change the type of the mountpoint. | |
2359 | */ | |
e462ec50 | 2360 | static int do_change_type(struct path *path, int ms_flags) |
07b20889 | 2361 | { |
315fc83e | 2362 | struct mount *m; |
4b8b21f4 | 2363 | struct mount *mnt = real_mount(path->mnt); |
e462ec50 | 2364 | int recurse = ms_flags & MS_REC; |
7a2e8a8f | 2365 | int type; |
719f5d7f | 2366 | int err = 0; |
07b20889 | 2367 | |
2d92ab3c | 2368 | if (path->dentry != path->mnt->mnt_root) |
07b20889 RP |
2369 | return -EINVAL; |
2370 | ||
e462ec50 | 2371 | type = flags_to_propagation_type(ms_flags); |
7a2e8a8f VA |
2372 | if (!type) |
2373 | return -EINVAL; | |
2374 | ||
97216be0 | 2375 | namespace_lock(); |
719f5d7f MS |
2376 | if (type == MS_SHARED) { |
2377 | err = invent_group_ids(mnt, recurse); | |
2378 | if (err) | |
2379 | goto out_unlock; | |
2380 | } | |
2381 | ||
719ea2fb | 2382 | lock_mount_hash(); |
909b0a88 | 2383 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
0f0afb1d | 2384 | change_mnt_propagation(m, type); |
719ea2fb | 2385 | unlock_mount_hash(); |
719f5d7f MS |
2386 | |
2387 | out_unlock: | |
97216be0 | 2388 | namespace_unlock(); |
719f5d7f | 2389 | return err; |
07b20889 RP |
2390 | } |
2391 | ||
a07b2000 AV |
2392 | static struct mount *__do_loopback(struct path *old_path, int recurse) |
2393 | { | |
2394 | struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt); | |
2395 | ||
2396 | if (IS_MNT_UNBINDABLE(old)) | |
2397 | return mnt; | |
2398 | ||
2399 | if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) | |
2400 | return mnt; | |
2401 | ||
2402 | if (!recurse && has_locked_children(old, old_path->dentry)) | |
2403 | return mnt; | |
2404 | ||
2405 | if (recurse) | |
2406 | mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE); | |
2407 | else | |
2408 | mnt = clone_mnt(old, old_path->dentry, 0); | |
2409 | ||
2410 | if (!IS_ERR(mnt)) | |
2411 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
2412 | ||
2413 | return mnt; | |
2414 | } | |
2415 | ||
1da177e4 LT |
2416 | /* |
2417 | * do loopback mount. | |
2418 | */ | |
808d4e3c | 2419 | static int do_loopback(struct path *path, const char *old_name, |
2dafe1c4 | 2420 | int recurse) |
1da177e4 | 2421 | { |
2d92ab3c | 2422 | struct path old_path; |
a07b2000 | 2423 | struct mount *mnt = NULL, *parent; |
84d17192 | 2424 | struct mountpoint *mp; |
57eccb83 | 2425 | int err; |
1da177e4 LT |
2426 | if (!old_name || !*old_name) |
2427 | return -EINVAL; | |
815d405c | 2428 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
1da177e4 LT |
2429 | if (err) |
2430 | return err; | |
2431 | ||
8823c079 | 2432 | err = -EINVAL; |
4ce5d2b1 | 2433 | if (mnt_ns_loop(old_path.dentry)) |
dd111b31 | 2434 | goto out; |
8823c079 | 2435 | |
84d17192 | 2436 | mp = lock_mount(path); |
a07b2000 AV |
2437 | if (IS_ERR(mp)) { |
2438 | err = PTR_ERR(mp); | |
b12cea91 | 2439 | goto out; |
a07b2000 | 2440 | } |
b12cea91 | 2441 | |
84d17192 | 2442 | parent = real_mount(path->mnt); |
e149ed2b AV |
2443 | if (!check_mnt(parent)) |
2444 | goto out2; | |
2445 | ||
a07b2000 | 2446 | mnt = __do_loopback(&old_path, recurse); |
be34d1a3 DH |
2447 | if (IS_ERR(mnt)) { |
2448 | err = PTR_ERR(mnt); | |
e9c5d8a5 | 2449 | goto out2; |
be34d1a3 | 2450 | } |
ccd48bc7 | 2451 | |
84d17192 | 2452 | err = graft_tree(mnt, parent, mp); |
ccd48bc7 | 2453 | if (err) { |
719ea2fb | 2454 | lock_mount_hash(); |
e819f152 | 2455 | umount_tree(mnt, UMOUNT_SYNC); |
719ea2fb | 2456 | unlock_mount_hash(); |
5b83d2c5 | 2457 | } |
b12cea91 | 2458 | out2: |
84d17192 | 2459 | unlock_mount(mp); |
ccd48bc7 | 2460 | out: |
2d92ab3c | 2461 | path_put(&old_path); |
1da177e4 LT |
2462 | return err; |
2463 | } | |
2464 | ||
a07b2000 AV |
2465 | static struct file *open_detached_copy(struct path *path, bool recursive) |
2466 | { | |
2467 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; | |
2468 | struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true); | |
2469 | struct mount *mnt, *p; | |
2470 | struct file *file; | |
2471 | ||
2472 | if (IS_ERR(ns)) | |
2473 | return ERR_CAST(ns); | |
2474 | ||
2475 | namespace_lock(); | |
2476 | mnt = __do_loopback(path, recursive); | |
2477 | if (IS_ERR(mnt)) { | |
2478 | namespace_unlock(); | |
2479 | free_mnt_ns(ns); | |
2480 | return ERR_CAST(mnt); | |
2481 | } | |
2482 | ||
2483 | lock_mount_hash(); | |
2484 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
2485 | p->mnt_ns = ns; | |
2486 | ns->mounts++; | |
2487 | } | |
2488 | ns->root = mnt; | |
2489 | list_add_tail(&ns->list, &mnt->mnt_list); | |
2490 | mntget(&mnt->mnt); | |
2491 | unlock_mount_hash(); | |
2492 | namespace_unlock(); | |
2493 | ||
2494 | mntput(path->mnt); | |
2495 | path->mnt = &mnt->mnt; | |
2496 | file = dentry_open(path, O_PATH, current_cred()); | |
2497 | if (IS_ERR(file)) | |
2498 | dissolve_on_fput(path->mnt); | |
2499 | else | |
2500 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
2501 | return file; | |
2502 | } | |
2503 | ||
2658ce09 | 2504 | SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags) |
a07b2000 AV |
2505 | { |
2506 | struct file *file; | |
2507 | struct path path; | |
2508 | int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; | |
2509 | bool detached = flags & OPEN_TREE_CLONE; | |
2510 | int error; | |
2511 | int fd; | |
2512 | ||
2513 | BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); | |
2514 | ||
2515 | if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE | | |
2516 | AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE | | |
2517 | OPEN_TREE_CLOEXEC)) | |
2518 | return -EINVAL; | |
2519 | ||
2520 | if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE) | |
2521 | return -EINVAL; | |
2522 | ||
2523 | if (flags & AT_NO_AUTOMOUNT) | |
2524 | lookup_flags &= ~LOOKUP_AUTOMOUNT; | |
2525 | if (flags & AT_SYMLINK_NOFOLLOW) | |
2526 | lookup_flags &= ~LOOKUP_FOLLOW; | |
2527 | if (flags & AT_EMPTY_PATH) | |
2528 | lookup_flags |= LOOKUP_EMPTY; | |
2529 | ||
2530 | if (detached && !may_mount()) | |
2531 | return -EPERM; | |
2532 | ||
2533 | fd = get_unused_fd_flags(flags & O_CLOEXEC); | |
2534 | if (fd < 0) | |
2535 | return fd; | |
2536 | ||
2537 | error = user_path_at(dfd, filename, lookup_flags, &path); | |
2538 | if (unlikely(error)) { | |
2539 | file = ERR_PTR(error); | |
2540 | } else { | |
2541 | if (detached) | |
2542 | file = open_detached_copy(&path, flags & AT_RECURSIVE); | |
2543 | else | |
2544 | file = dentry_open(&path, O_PATH, current_cred()); | |
2545 | path_put(&path); | |
2546 | } | |
2547 | if (IS_ERR(file)) { | |
2548 | put_unused_fd(fd); | |
2549 | return PTR_ERR(file); | |
2550 | } | |
2551 | fd_install(fd, file); | |
2552 | return fd; | |
2553 | } | |
2554 | ||
43f5e655 DH |
2555 | /* |
2556 | * Don't allow locked mount flags to be cleared. | |
2557 | * | |
2558 | * No locks need to be held here while testing the various MNT_LOCK | |
2559 | * flags because those flags can never be cleared once they are set. | |
2560 | */ | |
2561 | static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2562 | { |
43f5e655 DH |
2563 | unsigned int fl = mnt->mnt.mnt_flags; |
2564 | ||
2565 | if ((fl & MNT_LOCK_READONLY) && | |
2566 | !(mnt_flags & MNT_READONLY)) | |
2567 | return false; | |
2568 | ||
2569 | if ((fl & MNT_LOCK_NODEV) && | |
2570 | !(mnt_flags & MNT_NODEV)) | |
2571 | return false; | |
2572 | ||
2573 | if ((fl & MNT_LOCK_NOSUID) && | |
2574 | !(mnt_flags & MNT_NOSUID)) | |
2575 | return false; | |
2576 | ||
2577 | if ((fl & MNT_LOCK_NOEXEC) && | |
2578 | !(mnt_flags & MNT_NOEXEC)) | |
2579 | return false; | |
2580 | ||
2581 | if ((fl & MNT_LOCK_ATIME) && | |
2582 | ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) | |
2583 | return false; | |
2e4b7fcd | 2584 | |
43f5e655 DH |
2585 | return true; |
2586 | } | |
2587 | ||
2588 | static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags) | |
2e4b7fcd | 2589 | { |
43f5e655 | 2590 | bool readonly_request = (mnt_flags & MNT_READONLY); |
2e4b7fcd | 2591 | |
43f5e655 | 2592 | if (readonly_request == __mnt_is_readonly(&mnt->mnt)) |
2e4b7fcd DH |
2593 | return 0; |
2594 | ||
2595 | if (readonly_request) | |
43f5e655 DH |
2596 | return mnt_make_readonly(mnt); |
2597 | ||
68847c94 CB |
2598 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
2599 | return 0; | |
43f5e655 DH |
2600 | } |
2601 | ||
43f5e655 DH |
2602 | static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) |
2603 | { | |
43f5e655 DH |
2604 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
2605 | mnt->mnt.mnt_flags = mnt_flags; | |
2606 | touch_mnt_namespace(mnt->mnt_ns); | |
43f5e655 DH |
2607 | } |
2608 | ||
f8b92ba6 DD |
2609 | static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt) |
2610 | { | |
2611 | struct super_block *sb = mnt->mnt_sb; | |
2612 | ||
2613 | if (!__mnt_is_readonly(mnt) && | |
a128b054 | 2614 | (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) && |
f8b92ba6 DD |
2615 | (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { |
2616 | char *buf = (char *)__get_free_page(GFP_KERNEL); | |
2617 | char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM); | |
2618 | struct tm tm; | |
2619 | ||
2620 | time64_to_tm(sb->s_time_max, 0, &tm); | |
2621 | ||
0ecee669 EB |
2622 | pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n", |
2623 | sb->s_type->name, | |
2624 | is_mounted(mnt) ? "remounted" : "mounted", | |
2625 | mntpath, | |
f8b92ba6 DD |
2626 | tm.tm_year+1900, (unsigned long long)sb->s_time_max); |
2627 | ||
2628 | free_page((unsigned long)buf); | |
a128b054 | 2629 | sb->s_iflags |= SB_I_TS_EXPIRY_WARNED; |
f8b92ba6 DD |
2630 | } |
2631 | } | |
2632 | ||
43f5e655 DH |
2633 | /* |
2634 | * Handle reconfiguration of the mountpoint only without alteration of the | |
2635 | * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND | |
2636 | * to mount(2). | |
2637 | */ | |
2638 | static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags) | |
2639 | { | |
2640 | struct super_block *sb = path->mnt->mnt_sb; | |
2641 | struct mount *mnt = real_mount(path->mnt); | |
2642 | int ret; | |
2643 | ||
2644 | if (!check_mnt(mnt)) | |
2645 | return -EINVAL; | |
2646 | ||
2647 | if (path->dentry != mnt->mnt.mnt_root) | |
2648 | return -EINVAL; | |
2649 | ||
2650 | if (!can_change_locked_flags(mnt, mnt_flags)) | |
2651 | return -EPERM; | |
2652 | ||
e58ace1a CB |
2653 | /* |
2654 | * We're only checking whether the superblock is read-only not | |
2655 | * changing it, so only take down_read(&sb->s_umount). | |
2656 | */ | |
2657 | down_read(&sb->s_umount); | |
68847c94 | 2658 | lock_mount_hash(); |
43f5e655 DH |
2659 | ret = change_mount_ro_state(mnt, mnt_flags); |
2660 | if (ret == 0) | |
2661 | set_mount_attributes(mnt, mnt_flags); | |
68847c94 | 2662 | unlock_mount_hash(); |
e58ace1a | 2663 | up_read(&sb->s_umount); |
f8b92ba6 DD |
2664 | |
2665 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2666 | ||
43f5e655 | 2667 | return ret; |
2e4b7fcd DH |
2668 | } |
2669 | ||
1da177e4 LT |
2670 | /* |
2671 | * change filesystem flags. dir should be a physical root of filesystem. | |
2672 | * If you've mounted a non-root directory somewhere and want to do remount | |
2673 | * on it - tough luck. | |
2674 | */ | |
e462ec50 DH |
2675 | static int do_remount(struct path *path, int ms_flags, int sb_flags, |
2676 | int mnt_flags, void *data) | |
1da177e4 LT |
2677 | { |
2678 | int err; | |
2d92ab3c | 2679 | struct super_block *sb = path->mnt->mnt_sb; |
143c8c91 | 2680 | struct mount *mnt = real_mount(path->mnt); |
8d0347f6 | 2681 | struct fs_context *fc; |
1da177e4 | 2682 | |
143c8c91 | 2683 | if (!check_mnt(mnt)) |
1da177e4 LT |
2684 | return -EINVAL; |
2685 | ||
2d92ab3c | 2686 | if (path->dentry != path->mnt->mnt_root) |
1da177e4 LT |
2687 | return -EINVAL; |
2688 | ||
43f5e655 | 2689 | if (!can_change_locked_flags(mnt, mnt_flags)) |
9566d674 | 2690 | return -EPERM; |
9566d674 | 2691 | |
8d0347f6 DH |
2692 | fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK); |
2693 | if (IS_ERR(fc)) | |
2694 | return PTR_ERR(fc); | |
ff36fe2c | 2695 | |
b330966f | 2696 | fc->oldapi = true; |
8d0347f6 DH |
2697 | err = parse_monolithic_mount_data(fc, data); |
2698 | if (!err) { | |
2699 | down_write(&sb->s_umount); | |
2700 | err = -EPERM; | |
2701 | if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { | |
2702 | err = reconfigure_super(fc); | |
68847c94 CB |
2703 | if (!err) { |
2704 | lock_mount_hash(); | |
8d0347f6 | 2705 | set_mount_attributes(mnt, mnt_flags); |
68847c94 CB |
2706 | unlock_mount_hash(); |
2707 | } | |
8d0347f6 DH |
2708 | } |
2709 | up_write(&sb->s_umount); | |
0e55a7cc | 2710 | } |
f8b92ba6 DD |
2711 | |
2712 | mnt_warn_timestamp_expiry(path, &mnt->mnt); | |
2713 | ||
8d0347f6 | 2714 | put_fs_context(fc); |
1da177e4 LT |
2715 | return err; |
2716 | } | |
2717 | ||
cbbe362c | 2718 | static inline int tree_contains_unbindable(struct mount *mnt) |
9676f0c6 | 2719 | { |
315fc83e | 2720 | struct mount *p; |
909b0a88 | 2721 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
fc7be130 | 2722 | if (IS_MNT_UNBINDABLE(p)) |
9676f0c6 RP |
2723 | return 1; |
2724 | } | |
2725 | return 0; | |
2726 | } | |
2727 | ||
44dfd84a DH |
2728 | /* |
2729 | * Check that there aren't references to earlier/same mount namespaces in the | |
2730 | * specified subtree. Such references can act as pins for mount namespaces | |
2731 | * that aren't checked by the mount-cycle checking code, thereby allowing | |
2732 | * cycles to be made. | |
2733 | */ | |
2734 | static bool check_for_nsfs_mounts(struct mount *subtree) | |
2735 | { | |
2736 | struct mount *p; | |
2737 | bool ret = false; | |
2738 | ||
2739 | lock_mount_hash(); | |
2740 | for (p = subtree; p; p = next_mnt(p, subtree)) | |
2741 | if (mnt_ns_loop(p->mnt.mnt_root)) | |
2742 | goto out; | |
2743 | ||
2744 | ret = true; | |
2745 | out: | |
2746 | unlock_mount_hash(); | |
2747 | return ret; | |
2748 | } | |
2749 | ||
9ffb14ef PT |
2750 | static int do_set_group(struct path *from_path, struct path *to_path) |
2751 | { | |
2752 | struct mount *from, *to; | |
2753 | int err; | |
2754 | ||
2755 | from = real_mount(from_path->mnt); | |
2756 | to = real_mount(to_path->mnt); | |
2757 | ||
2758 | namespace_lock(); | |
2759 | ||
2760 | err = -EINVAL; | |
2761 | /* To and From must be mounted */ | |
2762 | if (!is_mounted(&from->mnt)) | |
2763 | goto out; | |
2764 | if (!is_mounted(&to->mnt)) | |
2765 | goto out; | |
2766 | ||
2767 | err = -EPERM; | |
2768 | /* We should be allowed to modify mount namespaces of both mounts */ | |
2769 | if (!ns_capable(from->mnt_ns->user_ns, CAP_SYS_ADMIN)) | |
2770 | goto out; | |
2771 | if (!ns_capable(to->mnt_ns->user_ns, CAP_SYS_ADMIN)) | |
2772 | goto out; | |
2773 | ||
2774 | err = -EINVAL; | |
2775 | /* To and From paths should be mount roots */ | |
2776 | if (from_path->dentry != from_path->mnt->mnt_root) | |
2777 | goto out; | |
2778 | if (to_path->dentry != to_path->mnt->mnt_root) | |
2779 | goto out; | |
2780 | ||
2781 | /* Setting sharing groups is only allowed across same superblock */ | |
2782 | if (from->mnt.mnt_sb != to->mnt.mnt_sb) | |
2783 | goto out; | |
2784 | ||
2785 | /* From mount root should be wider than To mount root */ | |
2786 | if (!is_subdir(to->mnt.mnt_root, from->mnt.mnt_root)) | |
2787 | goto out; | |
2788 | ||
2789 | /* From mount should not have locked children in place of To's root */ | |
2790 | if (has_locked_children(from, to->mnt.mnt_root)) | |
2791 | goto out; | |
2792 | ||
2793 | /* Setting sharing groups is only allowed on private mounts */ | |
2794 | if (IS_MNT_SHARED(to) || IS_MNT_SLAVE(to)) | |
2795 | goto out; | |
2796 | ||
2797 | /* From should not be private */ | |
2798 | if (!IS_MNT_SHARED(from) && !IS_MNT_SLAVE(from)) | |
2799 | goto out; | |
2800 | ||
2801 | if (IS_MNT_SLAVE(from)) { | |
2802 | struct mount *m = from->mnt_master; | |
2803 | ||
2804 | list_add(&to->mnt_slave, &m->mnt_slave_list); | |
2805 | to->mnt_master = m; | |
2806 | } | |
2807 | ||
2808 | if (IS_MNT_SHARED(from)) { | |
2809 | to->mnt_group_id = from->mnt_group_id; | |
2810 | list_add(&to->mnt_share, &from->mnt_share); | |
2811 | lock_mount_hash(); | |
2812 | set_mnt_shared(to); | |
2813 | unlock_mount_hash(); | |
2814 | } | |
2815 | ||
2816 | err = 0; | |
2817 | out: | |
2818 | namespace_unlock(); | |
2819 | return err; | |
2820 | } | |
2821 | ||
2db154b3 | 2822 | static int do_move_mount(struct path *old_path, struct path *new_path) |
1da177e4 | 2823 | { |
44dfd84a | 2824 | struct mnt_namespace *ns; |
676da58d | 2825 | struct mount *p; |
0fb54e50 | 2826 | struct mount *old; |
2763d119 AV |
2827 | struct mount *parent; |
2828 | struct mountpoint *mp, *old_mp; | |
57eccb83 | 2829 | int err; |
44dfd84a | 2830 | bool attached; |
1da177e4 | 2831 | |
2db154b3 | 2832 | mp = lock_mount(new_path); |
84d17192 | 2833 | if (IS_ERR(mp)) |
2db154b3 | 2834 | return PTR_ERR(mp); |
cc53ce53 | 2835 | |
2db154b3 DH |
2836 | old = real_mount(old_path->mnt); |
2837 | p = real_mount(new_path->mnt); | |
2763d119 | 2838 | parent = old->mnt_parent; |
44dfd84a | 2839 | attached = mnt_has_parent(old); |
2763d119 | 2840 | old_mp = old->mnt_mp; |
44dfd84a | 2841 | ns = old->mnt_ns; |
143c8c91 | 2842 | |
1da177e4 | 2843 | err = -EINVAL; |
44dfd84a DH |
2844 | /* The mountpoint must be in our namespace. */ |
2845 | if (!check_mnt(p)) | |
2db154b3 | 2846 | goto out; |
1da177e4 | 2847 | |
570d7a98 EB |
2848 | /* The thing moved must be mounted... */ |
2849 | if (!is_mounted(&old->mnt)) | |
44dfd84a DH |
2850 | goto out; |
2851 | ||
570d7a98 EB |
2852 | /* ... and either ours or the root of anon namespace */ |
2853 | if (!(attached ? check_mnt(old) : is_anon_ns(ns))) | |
2db154b3 | 2854 | goto out; |
5ff9d8a6 | 2855 | |
2db154b3 DH |
2856 | if (old->mnt.mnt_flags & MNT_LOCKED) |
2857 | goto out; | |
1da177e4 | 2858 | |
2db154b3 DH |
2859 | if (old_path->dentry != old_path->mnt->mnt_root) |
2860 | goto out; | |
1da177e4 | 2861 | |
2db154b3 DH |
2862 | if (d_is_dir(new_path->dentry) != |
2863 | d_is_dir(old_path->dentry)) | |
2864 | goto out; | |
21444403 RP |
2865 | /* |
2866 | * Don't move a mount residing in a shared parent. | |
2867 | */ | |
2763d119 | 2868 | if (attached && IS_MNT_SHARED(parent)) |
2db154b3 | 2869 | goto out; |
9676f0c6 RP |
2870 | /* |
2871 | * Don't move a mount tree containing unbindable mounts to a destination | |
2872 | * mount which is shared. | |
2873 | */ | |
fc7be130 | 2874 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
2db154b3 | 2875 | goto out; |
1da177e4 | 2876 | err = -ELOOP; |
44dfd84a DH |
2877 | if (!check_for_nsfs_mounts(old)) |
2878 | goto out; | |
fc7be130 | 2879 | for (; mnt_has_parent(p); p = p->mnt_parent) |
676da58d | 2880 | if (p == old) |
2db154b3 | 2881 | goto out; |
1da177e4 | 2882 | |
2db154b3 | 2883 | err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, |
2763d119 | 2884 | attached); |
4ac91378 | 2885 | if (err) |
2db154b3 | 2886 | goto out; |
1da177e4 LT |
2887 | |
2888 | /* if the mount is moved, it should no longer be expire | |
2889 | * automatically */ | |
6776db3d | 2890 | list_del_init(&old->mnt_expire); |
2763d119 AV |
2891 | if (attached) |
2892 | put_mountpoint(old_mp); | |
1da177e4 | 2893 | out: |
2db154b3 | 2894 | unlock_mount(mp); |
44dfd84a | 2895 | if (!err) { |
2763d119 AV |
2896 | if (attached) |
2897 | mntput_no_expire(parent); | |
2898 | else | |
44dfd84a DH |
2899 | free_mnt_ns(ns); |
2900 | } | |
2db154b3 DH |
2901 | return err; |
2902 | } | |
2903 | ||
2904 | static int do_move_mount_old(struct path *path, const char *old_name) | |
2905 | { | |
2906 | struct path old_path; | |
2907 | int err; | |
2908 | ||
2909 | if (!old_name || !*old_name) | |
2910 | return -EINVAL; | |
2911 | ||
2912 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); | |
2913 | if (err) | |
2914 | return err; | |
2915 | ||
2916 | err = do_move_mount(&old_path, path); | |
2d92ab3c | 2917 | path_put(&old_path); |
1da177e4 LT |
2918 | return err; |
2919 | } | |
2920 | ||
9d412a43 AV |
2921 | /* |
2922 | * add a mount into a namespace's mount tree | |
2923 | */ | |
8f11538e | 2924 | static int do_add_mount(struct mount *newmnt, struct mountpoint *mp, |
1e2d8464 | 2925 | const struct path *path, int mnt_flags) |
9d412a43 | 2926 | { |
8f11538e | 2927 | struct mount *parent = real_mount(path->mnt); |
9d412a43 | 2928 | |
f2ebb3a9 | 2929 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
9d412a43 | 2930 | |
84d17192 | 2931 | if (unlikely(!check_mnt(parent))) { |
156cacb1 AV |
2932 | /* that's acceptable only for automounts done in private ns */ |
2933 | if (!(mnt_flags & MNT_SHRINKABLE)) | |
8f11538e | 2934 | return -EINVAL; |
156cacb1 | 2935 | /* ... and for those we'd better have mountpoint still alive */ |
84d17192 | 2936 | if (!parent->mnt_ns) |
8f11538e | 2937 | return -EINVAL; |
156cacb1 | 2938 | } |
9d412a43 AV |
2939 | |
2940 | /* Refuse the same filesystem on the same mount point */ | |
95bc5f25 | 2941 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && |
9d412a43 | 2942 | path->mnt->mnt_root == path->dentry) |
8f11538e | 2943 | return -EBUSY; |
9d412a43 | 2944 | |
e36cb0b8 | 2945 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
8f11538e | 2946 | return -EINVAL; |
9d412a43 | 2947 | |
95bc5f25 | 2948 | newmnt->mnt.mnt_flags = mnt_flags; |
8f11538e | 2949 | return graft_tree(newmnt, parent, mp); |
9d412a43 | 2950 | } |
b1e75df4 | 2951 | |
132e4608 DH |
2952 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags); |
2953 | ||
2954 | /* | |
2955 | * Create a new mount using a superblock configuration and request it | |
2956 | * be added to the namespace tree. | |
2957 | */ | |
2958 | static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, | |
2959 | unsigned int mnt_flags) | |
2960 | { | |
2961 | struct vfsmount *mnt; | |
8f11538e | 2962 | struct mountpoint *mp; |
132e4608 DH |
2963 | struct super_block *sb = fc->root->d_sb; |
2964 | int error; | |
2965 | ||
c9ce29ed AV |
2966 | error = security_sb_kern_mount(sb); |
2967 | if (!error && mount_too_revealing(sb, &mnt_flags)) | |
2968 | error = -EPERM; | |
2969 | ||
2970 | if (unlikely(error)) { | |
2971 | fc_drop_locked(fc); | |
2972 | return error; | |
132e4608 DH |
2973 | } |
2974 | ||
2975 | up_write(&sb->s_umount); | |
2976 | ||
2977 | mnt = vfs_create_mount(fc); | |
2978 | if (IS_ERR(mnt)) | |
2979 | return PTR_ERR(mnt); | |
2980 | ||
f8b92ba6 DD |
2981 | mnt_warn_timestamp_expiry(mountpoint, mnt); |
2982 | ||
8f11538e AV |
2983 | mp = lock_mount(mountpoint); |
2984 | if (IS_ERR(mp)) { | |
2985 | mntput(mnt); | |
2986 | return PTR_ERR(mp); | |
2987 | } | |
2988 | error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags); | |
2989 | unlock_mount(mp); | |
0ecee669 EB |
2990 | if (error < 0) |
2991 | mntput(mnt); | |
132e4608 DH |
2992 | return error; |
2993 | } | |
1b852bce | 2994 | |
1da177e4 LT |
2995 | /* |
2996 | * create a new mount for userspace and request it to be added into the | |
2997 | * namespace's tree | |
2998 | */ | |
e462ec50 | 2999 | static int do_new_mount(struct path *path, const char *fstype, int sb_flags, |
808d4e3c | 3000 | int mnt_flags, const char *name, void *data) |
1da177e4 | 3001 | { |
0c55cfc4 | 3002 | struct file_system_type *type; |
a0c9a8b8 AV |
3003 | struct fs_context *fc; |
3004 | const char *subtype = NULL; | |
3005 | int err = 0; | |
1da177e4 | 3006 | |
0c55cfc4 | 3007 | if (!fstype) |
1da177e4 LT |
3008 | return -EINVAL; |
3009 | ||
0c55cfc4 EB |
3010 | type = get_fs_type(fstype); |
3011 | if (!type) | |
3012 | return -ENODEV; | |
3013 | ||
a0c9a8b8 AV |
3014 | if (type->fs_flags & FS_HAS_SUBTYPE) { |
3015 | subtype = strchr(fstype, '.'); | |
3016 | if (subtype) { | |
3017 | subtype++; | |
3018 | if (!*subtype) { | |
3019 | put_filesystem(type); | |
3020 | return -EINVAL; | |
3021 | } | |
a0c9a8b8 AV |
3022 | } |
3023 | } | |
0c55cfc4 | 3024 | |
a0c9a8b8 | 3025 | fc = fs_context_for_mount(type, sb_flags); |
0c55cfc4 | 3026 | put_filesystem(type); |
a0c9a8b8 AV |
3027 | if (IS_ERR(fc)) |
3028 | return PTR_ERR(fc); | |
3029 | ||
3e1aeb00 DH |
3030 | if (subtype) |
3031 | err = vfs_parse_fs_string(fc, "subtype", | |
3032 | subtype, strlen(subtype)); | |
3033 | if (!err && name) | |
3034 | err = vfs_parse_fs_string(fc, "source", name, strlen(name)); | |
a0c9a8b8 AV |
3035 | if (!err) |
3036 | err = parse_monolithic_mount_data(fc, data); | |
c3aabf07 AV |
3037 | if (!err && !mount_capable(fc)) |
3038 | err = -EPERM; | |
a0c9a8b8 AV |
3039 | if (!err) |
3040 | err = vfs_get_tree(fc); | |
132e4608 DH |
3041 | if (!err) |
3042 | err = do_new_mount_fc(fc, path, mnt_flags); | |
8654df4e | 3043 | |
a0c9a8b8 | 3044 | put_fs_context(fc); |
15f9a3f3 | 3045 | return err; |
1da177e4 LT |
3046 | } |
3047 | ||
1e2d8464 | 3048 | int finish_automount(struct vfsmount *m, const struct path *path) |
19a167af | 3049 | { |
26df6034 | 3050 | struct dentry *dentry = path->dentry; |
8f11538e | 3051 | struct mountpoint *mp; |
25e195aa | 3052 | struct mount *mnt; |
19a167af | 3053 | int err; |
25e195aa AV |
3054 | |
3055 | if (!m) | |
3056 | return 0; | |
3057 | if (IS_ERR(m)) | |
3058 | return PTR_ERR(m); | |
3059 | ||
3060 | mnt = real_mount(m); | |
19a167af AV |
3061 | /* The new mount record should have at least 2 refs to prevent it being |
3062 | * expired before we get a chance to add it | |
3063 | */ | |
6776db3d | 3064 | BUG_ON(mnt_get_count(mnt) < 2); |
19a167af AV |
3065 | |
3066 | if (m->mnt_sb == path->mnt->mnt_sb && | |
26df6034 | 3067 | m->mnt_root == dentry) { |
b1e75df4 | 3068 | err = -ELOOP; |
26df6034 | 3069 | goto discard; |
19a167af AV |
3070 | } |
3071 | ||
26df6034 AV |
3072 | /* |
3073 | * we don't want to use lock_mount() - in this case finding something | |
3074 | * that overmounts our mountpoint to be means "quitely drop what we've | |
3075 | * got", not "try to mount it on top". | |
3076 | */ | |
3077 | inode_lock(dentry->d_inode); | |
3078 | namespace_lock(); | |
3079 | if (unlikely(cant_mount(dentry))) { | |
3080 | err = -ENOENT; | |
3081 | goto discard_locked; | |
3082 | } | |
3083 | rcu_read_lock(); | |
3084 | if (unlikely(__lookup_mnt(path->mnt, dentry))) { | |
3085 | rcu_read_unlock(); | |
3086 | err = 0; | |
3087 | goto discard_locked; | |
3088 | } | |
3089 | rcu_read_unlock(); | |
3090 | mp = get_mountpoint(dentry); | |
8f11538e AV |
3091 | if (IS_ERR(mp)) { |
3092 | err = PTR_ERR(mp); | |
26df6034 | 3093 | goto discard_locked; |
8f11538e | 3094 | } |
26df6034 | 3095 | |
8f11538e AV |
3096 | err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
3097 | unlock_mount(mp); | |
26df6034 AV |
3098 | if (unlikely(err)) |
3099 | goto discard; | |
3100 | mntput(m); | |
3101 | return 0; | |
3102 | ||
3103 | discard_locked: | |
3104 | namespace_unlock(); | |
3105 | inode_unlock(dentry->d_inode); | |
3106 | discard: | |
b1e75df4 | 3107 | /* remove m from any expiration list it may be on */ |
6776db3d | 3108 | if (!list_empty(&mnt->mnt_expire)) { |
97216be0 | 3109 | namespace_lock(); |
6776db3d | 3110 | list_del_init(&mnt->mnt_expire); |
97216be0 | 3111 | namespace_unlock(); |
19a167af | 3112 | } |
b1e75df4 AV |
3113 | mntput(m); |
3114 | mntput(m); | |
19a167af AV |
3115 | return err; |
3116 | } | |
3117 | ||
ea5b778a DH |
3118 | /** |
3119 | * mnt_set_expiry - Put a mount on an expiration list | |
3120 | * @mnt: The mount to list. | |
3121 | * @expiry_list: The list to add the mount to. | |
3122 | */ | |
3123 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) | |
3124 | { | |
97216be0 | 3125 | namespace_lock(); |
ea5b778a | 3126 | |
6776db3d | 3127 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
ea5b778a | 3128 | |
97216be0 | 3129 | namespace_unlock(); |
ea5b778a DH |
3130 | } |
3131 | EXPORT_SYMBOL(mnt_set_expiry); | |
3132 | ||
1da177e4 LT |
3133 | /* |
3134 | * process a list of expirable mountpoints with the intent of discarding any | |
3135 | * mountpoints that aren't in use and haven't been touched since last we came | |
3136 | * here | |
3137 | */ | |
3138 | void mark_mounts_for_expiry(struct list_head *mounts) | |
3139 | { | |
761d5c38 | 3140 | struct mount *mnt, *next; |
1da177e4 LT |
3141 | LIST_HEAD(graveyard); |
3142 | ||
3143 | if (list_empty(mounts)) | |
3144 | return; | |
3145 | ||
97216be0 | 3146 | namespace_lock(); |
719ea2fb | 3147 | lock_mount_hash(); |
1da177e4 LT |
3148 | |
3149 | /* extract from the expiration list every vfsmount that matches the | |
3150 | * following criteria: | |
3151 | * - only referenced by its parent vfsmount | |
3152 | * - still marked for expiry (marked on the last call here; marks are | |
3153 | * cleared by mntput()) | |
3154 | */ | |
6776db3d | 3155 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
863d684f | 3156 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
1ab59738 | 3157 | propagate_mount_busy(mnt, 1)) |
1da177e4 | 3158 | continue; |
6776db3d | 3159 | list_move(&mnt->mnt_expire, &graveyard); |
1da177e4 | 3160 | } |
bcc5c7d2 | 3161 | while (!list_empty(&graveyard)) { |
6776db3d | 3162 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
143c8c91 | 3163 | touch_mnt_namespace(mnt->mnt_ns); |
e819f152 | 3164 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 | 3165 | } |
719ea2fb | 3166 | unlock_mount_hash(); |
3ab6abee | 3167 | namespace_unlock(); |
5528f911 TM |
3168 | } |
3169 | ||
3170 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); | |
3171 | ||
3172 | /* | |
3173 | * Ripoff of 'select_parent()' | |
3174 | * | |
3175 | * search the list of submounts for a given mountpoint, and move any | |
3176 | * shrinkable submounts to the 'graveyard' list. | |
3177 | */ | |
692afc31 | 3178 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
5528f911 | 3179 | { |
692afc31 | 3180 | struct mount *this_parent = parent; |
5528f911 TM |
3181 | struct list_head *next; |
3182 | int found = 0; | |
3183 | ||
3184 | repeat: | |
6b41d536 | 3185 | next = this_parent->mnt_mounts.next; |
5528f911 | 3186 | resume: |
6b41d536 | 3187 | while (next != &this_parent->mnt_mounts) { |
5528f911 | 3188 | struct list_head *tmp = next; |
6b41d536 | 3189 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
5528f911 TM |
3190 | |
3191 | next = tmp->next; | |
692afc31 | 3192 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
1da177e4 | 3193 | continue; |
5528f911 TM |
3194 | /* |
3195 | * Descend a level if the d_mounts list is non-empty. | |
3196 | */ | |
6b41d536 | 3197 | if (!list_empty(&mnt->mnt_mounts)) { |
5528f911 TM |
3198 | this_parent = mnt; |
3199 | goto repeat; | |
3200 | } | |
1da177e4 | 3201 | |
1ab59738 | 3202 | if (!propagate_mount_busy(mnt, 1)) { |
6776db3d | 3203 | list_move_tail(&mnt->mnt_expire, graveyard); |
5528f911 TM |
3204 | found++; |
3205 | } | |
1da177e4 | 3206 | } |
5528f911 TM |
3207 | /* |
3208 | * All done at this level ... ascend and resume the search | |
3209 | */ | |
3210 | if (this_parent != parent) { | |
6b41d536 | 3211 | next = this_parent->mnt_child.next; |
0714a533 | 3212 | this_parent = this_parent->mnt_parent; |
5528f911 TM |
3213 | goto resume; |
3214 | } | |
3215 | return found; | |
3216 | } | |
3217 | ||
3218 | /* | |
3219 | * process a list of expirable mountpoints with the intent of discarding any | |
3220 | * submounts of a specific parent mountpoint | |
99b7db7b | 3221 | * |
48a066e7 | 3222 | * mount_lock must be held for write |
5528f911 | 3223 | */ |
b54b9be7 | 3224 | static void shrink_submounts(struct mount *mnt) |
5528f911 TM |
3225 | { |
3226 | LIST_HEAD(graveyard); | |
761d5c38 | 3227 | struct mount *m; |
5528f911 | 3228 | |
5528f911 | 3229 | /* extract submounts of 'mountpoint' from the expiration list */ |
c35038be | 3230 | while (select_submounts(mnt, &graveyard)) { |
bcc5c7d2 | 3231 | while (!list_empty(&graveyard)) { |
761d5c38 | 3232 | m = list_first_entry(&graveyard, struct mount, |
6776db3d | 3233 | mnt_expire); |
143c8c91 | 3234 | touch_mnt_namespace(m->mnt_ns); |
e819f152 | 3235 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
bcc5c7d2 AV |
3236 | } |
3237 | } | |
1da177e4 LT |
3238 | } |
3239 | ||
028abd92 | 3240 | static void *copy_mount_options(const void __user * data) |
1da177e4 | 3241 | { |
b40ef869 | 3242 | char *copy; |
d563d678 | 3243 | unsigned left, offset; |
b58fed8b | 3244 | |
1da177e4 | 3245 | if (!data) |
b40ef869 | 3246 | return NULL; |
1da177e4 | 3247 | |
b40ef869 AV |
3248 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
3249 | if (!copy) | |
3250 | return ERR_PTR(-ENOMEM); | |
1da177e4 | 3251 | |
d563d678 | 3252 | left = copy_from_user(copy, data, PAGE_SIZE); |
1da177e4 | 3253 | |
d563d678 CM |
3254 | /* |
3255 | * Not all architectures have an exact copy_from_user(). Resort to | |
3256 | * byte at a time. | |
3257 | */ | |
3258 | offset = PAGE_SIZE - left; | |
3259 | while (left) { | |
3260 | char c; | |
3261 | if (get_user(c, (const char __user *)data + offset)) | |
3262 | break; | |
3263 | copy[offset] = c; | |
3264 | left--; | |
3265 | offset++; | |
3266 | } | |
3267 | ||
3268 | if (left == PAGE_SIZE) { | |
b40ef869 AV |
3269 | kfree(copy); |
3270 | return ERR_PTR(-EFAULT); | |
1da177e4 | 3271 | } |
d563d678 | 3272 | |
b40ef869 | 3273 | return copy; |
1da177e4 LT |
3274 | } |
3275 | ||
028abd92 | 3276 | static char *copy_mount_string(const void __user *data) |
eca6f534 | 3277 | { |
fbdb4401 | 3278 | return data ? strndup_user(data, PATH_MAX) : NULL; |
eca6f534 VN |
3279 | } |
3280 | ||
1da177e4 LT |
3281 | /* |
3282 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to | |
3283 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). | |
3284 | * | |
3285 | * data is a (void *) that can point to any structure up to | |
3286 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent | |
3287 | * information (or be NULL). | |
3288 | * | |
3289 | * Pre-0.97 versions of mount() didn't have a flags word. | |
3290 | * When the flags word was introduced its top half was required | |
3291 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. | |
3292 | * Therefore, if this magic number is present, it carries no information | |
3293 | * and must be discarded. | |
3294 | */ | |
c60166f0 | 3295 | int path_mount(const char *dev_name, struct path *path, |
808d4e3c | 3296 | const char *type_page, unsigned long flags, void *data_page) |
1da177e4 | 3297 | { |
e462ec50 | 3298 | unsigned int mnt_flags = 0, sb_flags; |
a1e6aaa3 | 3299 | int ret; |
1da177e4 LT |
3300 | |
3301 | /* Discard magic */ | |
3302 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) | |
3303 | flags &= ~MS_MGC_MSK; | |
3304 | ||
3305 | /* Basic sanity checks */ | |
1da177e4 LT |
3306 | if (data_page) |
3307 | ((char *)data_page)[PAGE_SIZE - 1] = 0; | |
3308 | ||
e462ec50 DH |
3309 | if (flags & MS_NOUSER) |
3310 | return -EINVAL; | |
3311 | ||
a1e6aaa3 CH |
3312 | ret = security_sb_mount(dev_name, path, type_page, flags, data_page); |
3313 | if (ret) | |
3314 | return ret; | |
3315 | if (!may_mount()) | |
3316 | return -EPERM; | |
f7e33bdb JL |
3317 | if (flags & SB_MANDLOCK) |
3318 | warn_mandlock(); | |
a27ab9f2 | 3319 | |
613cbe3d AK |
3320 | /* Default to relatime unless overriden */ |
3321 | if (!(flags & MS_NOATIME)) | |
3322 | mnt_flags |= MNT_RELATIME; | |
0a1c01c9 | 3323 | |
1da177e4 LT |
3324 | /* Separate the per-mountpoint flags */ |
3325 | if (flags & MS_NOSUID) | |
3326 | mnt_flags |= MNT_NOSUID; | |
3327 | if (flags & MS_NODEV) | |
3328 | mnt_flags |= MNT_NODEV; | |
3329 | if (flags & MS_NOEXEC) | |
3330 | mnt_flags |= MNT_NOEXEC; | |
fc33a7bb CH |
3331 | if (flags & MS_NOATIME) |
3332 | mnt_flags |= MNT_NOATIME; | |
3333 | if (flags & MS_NODIRATIME) | |
3334 | mnt_flags |= MNT_NODIRATIME; | |
d0adde57 MG |
3335 | if (flags & MS_STRICTATIME) |
3336 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); | |
a9e5b732 | 3337 | if (flags & MS_RDONLY) |
2e4b7fcd | 3338 | mnt_flags |= MNT_READONLY; |
dab741e0 MN |
3339 | if (flags & MS_NOSYMFOLLOW) |
3340 | mnt_flags |= MNT_NOSYMFOLLOW; | |
fc33a7bb | 3341 | |
ffbc6f0e EB |
3342 | /* The default atime for remount is preservation */ |
3343 | if ((flags & MS_REMOUNT) && | |
3344 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | | |
3345 | MS_STRICTATIME)) == 0)) { | |
3346 | mnt_flags &= ~MNT_ATIME_MASK; | |
a1e6aaa3 | 3347 | mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; |
ffbc6f0e EB |
3348 | } |
3349 | ||
e462ec50 DH |
3350 | sb_flags = flags & (SB_RDONLY | |
3351 | SB_SYNCHRONOUS | | |
3352 | SB_MANDLOCK | | |
3353 | SB_DIRSYNC | | |
3354 | SB_SILENT | | |
917086ff | 3355 | SB_POSIXACL | |
d7ee9469 | 3356 | SB_LAZYTIME | |
917086ff | 3357 | SB_I_VERSION); |
1da177e4 | 3358 | |
43f5e655 | 3359 | if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) |
a1e6aaa3 CH |
3360 | return do_reconfigure_mnt(path, mnt_flags); |
3361 | if (flags & MS_REMOUNT) | |
3362 | return do_remount(path, flags, sb_flags, mnt_flags, data_page); | |
3363 | if (flags & MS_BIND) | |
3364 | return do_loopback(path, dev_name, flags & MS_REC); | |
3365 | if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) | |
3366 | return do_change_type(path, flags); | |
3367 | if (flags & MS_MOVE) | |
3368 | return do_move_mount_old(path, dev_name); | |
3369 | ||
3370 | return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, | |
3371 | data_page); | |
3372 | } | |
3373 | ||
3374 | long do_mount(const char *dev_name, const char __user *dir_name, | |
3375 | const char *type_page, unsigned long flags, void *data_page) | |
3376 | { | |
3377 | struct path path; | |
3378 | int ret; | |
3379 | ||
3380 | ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); | |
3381 | if (ret) | |
3382 | return ret; | |
3383 | ret = path_mount(dev_name, &path, type_page, flags, data_page); | |
2d92ab3c | 3384 | path_put(&path); |
a1e6aaa3 | 3385 | return ret; |
1da177e4 LT |
3386 | } |
3387 | ||
537f7ccb EB |
3388 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
3389 | { | |
3390 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); | |
3391 | } | |
3392 | ||
3393 | static void dec_mnt_namespaces(struct ucounts *ucounts) | |
3394 | { | |
3395 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); | |
3396 | } | |
3397 | ||
771b1371 EB |
3398 | static void free_mnt_ns(struct mnt_namespace *ns) |
3399 | { | |
74e83122 AV |
3400 | if (!is_anon_ns(ns)) |
3401 | ns_free_inum(&ns->ns); | |
537f7ccb | 3402 | dec_mnt_namespaces(ns->ucounts); |
771b1371 EB |
3403 | put_user_ns(ns->user_ns); |
3404 | kfree(ns); | |
3405 | } | |
3406 | ||
8823c079 EB |
3407 | /* |
3408 | * Assign a sequence number so we can detect when we attempt to bind | |
3409 | * mount a reference to an older mount namespace into the current | |
3410 | * mount namespace, preventing reference counting loops. A 64bit | |
3411 | * number incrementing at 10Ghz will take 12,427 years to wrap which | |
3412 | * is effectively never, so we can ignore the possibility. | |
3413 | */ | |
3414 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); | |
3415 | ||
74e83122 | 3416 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon) |
cf8d2c11 TM |
3417 | { |
3418 | struct mnt_namespace *new_ns; | |
537f7ccb | 3419 | struct ucounts *ucounts; |
98f842e6 | 3420 | int ret; |
cf8d2c11 | 3421 | |
537f7ccb EB |
3422 | ucounts = inc_mnt_namespaces(user_ns); |
3423 | if (!ucounts) | |
df75e774 | 3424 | return ERR_PTR(-ENOSPC); |
537f7ccb | 3425 | |
30acd0bd | 3426 | new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL_ACCOUNT); |
537f7ccb EB |
3427 | if (!new_ns) { |
3428 | dec_mnt_namespaces(ucounts); | |
cf8d2c11 | 3429 | return ERR_PTR(-ENOMEM); |
537f7ccb | 3430 | } |
74e83122 AV |
3431 | if (!anon) { |
3432 | ret = ns_alloc_inum(&new_ns->ns); | |
3433 | if (ret) { | |
3434 | kfree(new_ns); | |
3435 | dec_mnt_namespaces(ucounts); | |
3436 | return ERR_PTR(ret); | |
3437 | } | |
98f842e6 | 3438 | } |
33c42940 | 3439 | new_ns->ns.ops = &mntns_operations; |
74e83122 AV |
3440 | if (!anon) |
3441 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); | |
1a7b8969 | 3442 | refcount_set(&new_ns->ns.count, 1); |
cf8d2c11 TM |
3443 | INIT_LIST_HEAD(&new_ns->list); |
3444 | init_waitqueue_head(&new_ns->poll); | |
9f6c61f9 | 3445 | spin_lock_init(&new_ns->ns_lock); |
771b1371 | 3446 | new_ns->user_ns = get_user_ns(user_ns); |
537f7ccb | 3447 | new_ns->ucounts = ucounts; |
cf8d2c11 TM |
3448 | return new_ns; |
3449 | } | |
3450 | ||
0766f788 | 3451 | __latent_entropy |
9559f689 AV |
3452 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
3453 | struct user_namespace *user_ns, struct fs_struct *new_fs) | |
1da177e4 | 3454 | { |
6b3286ed | 3455 | struct mnt_namespace *new_ns; |
7f2da1e7 | 3456 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
315fc83e | 3457 | struct mount *p, *q; |
9559f689 | 3458 | struct mount *old; |
cb338d06 | 3459 | struct mount *new; |
7a472ef4 | 3460 | int copy_flags; |
1da177e4 | 3461 | |
9559f689 AV |
3462 | BUG_ON(!ns); |
3463 | ||
3464 | if (likely(!(flags & CLONE_NEWNS))) { | |
3465 | get_mnt_ns(ns); | |
3466 | return ns; | |
3467 | } | |
3468 | ||
3469 | old = ns->root; | |
3470 | ||
74e83122 | 3471 | new_ns = alloc_mnt_ns(user_ns, false); |
cf8d2c11 TM |
3472 | if (IS_ERR(new_ns)) |
3473 | return new_ns; | |
1da177e4 | 3474 | |
97216be0 | 3475 | namespace_lock(); |
1da177e4 | 3476 | /* First pass: copy the tree topology */ |
4ce5d2b1 | 3477 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
9559f689 | 3478 | if (user_ns != ns->user_ns) |
3bd045cc | 3479 | copy_flags |= CL_SHARED_TO_SLAVE; |
7a472ef4 | 3480 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
be34d1a3 | 3481 | if (IS_ERR(new)) { |
328e6d90 | 3482 | namespace_unlock(); |
771b1371 | 3483 | free_mnt_ns(new_ns); |
be34d1a3 | 3484 | return ERR_CAST(new); |
1da177e4 | 3485 | } |
3bd045cc AV |
3486 | if (user_ns != ns->user_ns) { |
3487 | lock_mount_hash(); | |
3488 | lock_mnt_tree(new); | |
3489 | unlock_mount_hash(); | |
3490 | } | |
be08d6d2 | 3491 | new_ns->root = new; |
1a4eeaf2 | 3492 | list_add_tail(&new_ns->list, &new->mnt_list); |
1da177e4 LT |
3493 | |
3494 | /* | |
3495 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts | |
3496 | * as belonging to new namespace. We have already acquired a private | |
3497 | * fs_struct, so tsk->fs->lock is not needed. | |
3498 | */ | |
909b0a88 | 3499 | p = old; |
cb338d06 | 3500 | q = new; |
1da177e4 | 3501 | while (p) { |
143c8c91 | 3502 | q->mnt_ns = new_ns; |
d2921684 | 3503 | new_ns->mounts++; |
9559f689 AV |
3504 | if (new_fs) { |
3505 | if (&p->mnt == new_fs->root.mnt) { | |
3506 | new_fs->root.mnt = mntget(&q->mnt); | |
315fc83e | 3507 | rootmnt = &p->mnt; |
1da177e4 | 3508 | } |
9559f689 AV |
3509 | if (&p->mnt == new_fs->pwd.mnt) { |
3510 | new_fs->pwd.mnt = mntget(&q->mnt); | |
315fc83e | 3511 | pwdmnt = &p->mnt; |
1da177e4 | 3512 | } |
1da177e4 | 3513 | } |
909b0a88 AV |
3514 | p = next_mnt(p, old); |
3515 | q = next_mnt(q, new); | |
4ce5d2b1 EB |
3516 | if (!q) |
3517 | break; | |
3518 | while (p->mnt.mnt_root != q->mnt.mnt_root) | |
3519 | p = next_mnt(p, old); | |
1da177e4 | 3520 | } |
328e6d90 | 3521 | namespace_unlock(); |
1da177e4 | 3522 | |
1da177e4 | 3523 | if (rootmnt) |
f03c6599 | 3524 | mntput(rootmnt); |
1da177e4 | 3525 | if (pwdmnt) |
f03c6599 | 3526 | mntput(pwdmnt); |
1da177e4 | 3527 | |
741a2951 | 3528 | return new_ns; |
1da177e4 LT |
3529 | } |
3530 | ||
74e83122 | 3531 | struct dentry *mount_subtree(struct vfsmount *m, const char *name) |
ea441d11 | 3532 | { |
74e83122 | 3533 | struct mount *mnt = real_mount(m); |
ea441d11 | 3534 | struct mnt_namespace *ns; |
d31da0f0 | 3535 | struct super_block *s; |
ea441d11 AV |
3536 | struct path path; |
3537 | int err; | |
3538 | ||
74e83122 AV |
3539 | ns = alloc_mnt_ns(&init_user_ns, true); |
3540 | if (IS_ERR(ns)) { | |
3541 | mntput(m); | |
ea441d11 | 3542 | return ERR_CAST(ns); |
74e83122 AV |
3543 | } |
3544 | mnt->mnt_ns = ns; | |
3545 | ns->root = mnt; | |
3546 | ns->mounts++; | |
3547 | list_add(&mnt->mnt_list, &ns->list); | |
ea441d11 | 3548 | |
74e83122 | 3549 | err = vfs_path_lookup(m->mnt_root, m, |
ea441d11 AV |
3550 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
3551 | ||
3552 | put_mnt_ns(ns); | |
3553 | ||
3554 | if (err) | |
3555 | return ERR_PTR(err); | |
3556 | ||
3557 | /* trade a vfsmount reference for active sb one */ | |
d31da0f0 AV |
3558 | s = path.mnt->mnt_sb; |
3559 | atomic_inc(&s->s_active); | |
ea441d11 AV |
3560 | mntput(path.mnt); |
3561 | /* lock the sucker */ | |
d31da0f0 | 3562 | down_write(&s->s_umount); |
ea441d11 AV |
3563 | /* ... and return the root of (sub)tree on it */ |
3564 | return path.dentry; | |
3565 | } | |
3566 | EXPORT_SYMBOL(mount_subtree); | |
3567 | ||
cccaa5e3 DB |
3568 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
3569 | char __user *, type, unsigned long, flags, void __user *, data) | |
1da177e4 | 3570 | { |
eca6f534 VN |
3571 | int ret; |
3572 | char *kernel_type; | |
eca6f534 | 3573 | char *kernel_dev; |
b40ef869 | 3574 | void *options; |
1da177e4 | 3575 | |
b8850d1f TG |
3576 | kernel_type = copy_mount_string(type); |
3577 | ret = PTR_ERR(kernel_type); | |
3578 | if (IS_ERR(kernel_type)) | |
eca6f534 | 3579 | goto out_type; |
1da177e4 | 3580 | |
b8850d1f TG |
3581 | kernel_dev = copy_mount_string(dev_name); |
3582 | ret = PTR_ERR(kernel_dev); | |
3583 | if (IS_ERR(kernel_dev)) | |
eca6f534 | 3584 | goto out_dev; |
1da177e4 | 3585 | |
b40ef869 AV |
3586 | options = copy_mount_options(data); |
3587 | ret = PTR_ERR(options); | |
3588 | if (IS_ERR(options)) | |
eca6f534 | 3589 | goto out_data; |
1da177e4 | 3590 | |
b40ef869 | 3591 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
1da177e4 | 3592 | |
b40ef869 | 3593 | kfree(options); |
eca6f534 VN |
3594 | out_data: |
3595 | kfree(kernel_dev); | |
3596 | out_dev: | |
eca6f534 VN |
3597 | kfree(kernel_type); |
3598 | out_type: | |
3599 | return ret; | |
1da177e4 LT |
3600 | } |
3601 | ||
dd8b477f CB |
3602 | #define FSMOUNT_VALID_FLAGS \ |
3603 | (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \ | |
3604 | MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME | \ | |
3605 | MOUNT_ATTR_NOSYMFOLLOW) | |
5b490500 | 3606 | |
9caccd41 | 3607 | #define MOUNT_SETATTR_VALID_FLAGS (FSMOUNT_VALID_FLAGS | MOUNT_ATTR_IDMAP) |
2a186721 CB |
3608 | |
3609 | #define MOUNT_SETATTR_PROPAGATION_FLAGS \ | |
3610 | (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED) | |
3611 | ||
5b490500 CB |
3612 | static unsigned int attr_flags_to_mnt_flags(u64 attr_flags) |
3613 | { | |
3614 | unsigned int mnt_flags = 0; | |
3615 | ||
3616 | if (attr_flags & MOUNT_ATTR_RDONLY) | |
3617 | mnt_flags |= MNT_READONLY; | |
3618 | if (attr_flags & MOUNT_ATTR_NOSUID) | |
3619 | mnt_flags |= MNT_NOSUID; | |
3620 | if (attr_flags & MOUNT_ATTR_NODEV) | |
3621 | mnt_flags |= MNT_NODEV; | |
3622 | if (attr_flags & MOUNT_ATTR_NOEXEC) | |
3623 | mnt_flags |= MNT_NOEXEC; | |
3624 | if (attr_flags & MOUNT_ATTR_NODIRATIME) | |
3625 | mnt_flags |= MNT_NODIRATIME; | |
dd8b477f CB |
3626 | if (attr_flags & MOUNT_ATTR_NOSYMFOLLOW) |
3627 | mnt_flags |= MNT_NOSYMFOLLOW; | |
5b490500 CB |
3628 | |
3629 | return mnt_flags; | |
3630 | } | |
3631 | ||
2db154b3 | 3632 | /* |
93766fbd DH |
3633 | * Create a kernel mount representation for a new, prepared superblock |
3634 | * (specified by fs_fd) and attach to an open_tree-like file descriptor. | |
3635 | */ | |
3636 | SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, | |
3637 | unsigned int, attr_flags) | |
3638 | { | |
3639 | struct mnt_namespace *ns; | |
3640 | struct fs_context *fc; | |
3641 | struct file *file; | |
3642 | struct path newmount; | |
3643 | struct mount *mnt; | |
3644 | struct fd f; | |
3645 | unsigned int mnt_flags = 0; | |
3646 | long ret; | |
3647 | ||
3648 | if (!may_mount()) | |
3649 | return -EPERM; | |
3650 | ||
3651 | if ((flags & ~(FSMOUNT_CLOEXEC)) != 0) | |
3652 | return -EINVAL; | |
3653 | ||
5b490500 | 3654 | if (attr_flags & ~FSMOUNT_VALID_FLAGS) |
93766fbd DH |
3655 | return -EINVAL; |
3656 | ||
5b490500 | 3657 | mnt_flags = attr_flags_to_mnt_flags(attr_flags); |
93766fbd DH |
3658 | |
3659 | switch (attr_flags & MOUNT_ATTR__ATIME) { | |
3660 | case MOUNT_ATTR_STRICTATIME: | |
3661 | break; | |
3662 | case MOUNT_ATTR_NOATIME: | |
3663 | mnt_flags |= MNT_NOATIME; | |
3664 | break; | |
3665 | case MOUNT_ATTR_RELATIME: | |
3666 | mnt_flags |= MNT_RELATIME; | |
3667 | break; | |
3668 | default: | |
3669 | return -EINVAL; | |
3670 | } | |
3671 | ||
3672 | f = fdget(fs_fd); | |
3673 | if (!f.file) | |
3674 | return -EBADF; | |
3675 | ||
3676 | ret = -EINVAL; | |
3677 | if (f.file->f_op != &fscontext_fops) | |
3678 | goto err_fsfd; | |
3679 | ||
3680 | fc = f.file->private_data; | |
3681 | ||
3682 | ret = mutex_lock_interruptible(&fc->uapi_mutex); | |
3683 | if (ret < 0) | |
3684 | goto err_fsfd; | |
3685 | ||
3686 | /* There must be a valid superblock or we can't mount it */ | |
3687 | ret = -EINVAL; | |
3688 | if (!fc->root) | |
3689 | goto err_unlock; | |
3690 | ||
3691 | ret = -EPERM; | |
3692 | if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { | |
3693 | pr_warn("VFS: Mount too revealing\n"); | |
3694 | goto err_unlock; | |
3695 | } | |
3696 | ||
3697 | ret = -EBUSY; | |
3698 | if (fc->phase != FS_CONTEXT_AWAITING_MOUNT) | |
3699 | goto err_unlock; | |
3700 | ||
f7e33bdb JL |
3701 | if (fc->sb_flags & SB_MANDLOCK) |
3702 | warn_mandlock(); | |
93766fbd DH |
3703 | |
3704 | newmount.mnt = vfs_create_mount(fc); | |
3705 | if (IS_ERR(newmount.mnt)) { | |
3706 | ret = PTR_ERR(newmount.mnt); | |
3707 | goto err_unlock; | |
3708 | } | |
3709 | newmount.dentry = dget(fc->root); | |
3710 | newmount.mnt->mnt_flags = mnt_flags; | |
3711 | ||
3712 | /* We've done the mount bit - now move the file context into more or | |
3713 | * less the same state as if we'd done an fspick(). We don't want to | |
3714 | * do any memory allocation or anything like that at this point as we | |
3715 | * don't want to have to handle any errors incurred. | |
3716 | */ | |
3717 | vfs_clean_context(fc); | |
3718 | ||
3719 | ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true); | |
3720 | if (IS_ERR(ns)) { | |
3721 | ret = PTR_ERR(ns); | |
3722 | goto err_path; | |
3723 | } | |
3724 | mnt = real_mount(newmount.mnt); | |
3725 | mnt->mnt_ns = ns; | |
3726 | ns->root = mnt; | |
3727 | ns->mounts = 1; | |
3728 | list_add(&mnt->mnt_list, &ns->list); | |
1b0b9cc8 | 3729 | mntget(newmount.mnt); |
93766fbd DH |
3730 | |
3731 | /* Attach to an apparent O_PATH fd with a note that we need to unmount | |
3732 | * it, not just simply put it. | |
3733 | */ | |
3734 | file = dentry_open(&newmount, O_PATH, fc->cred); | |
3735 | if (IS_ERR(file)) { | |
3736 | dissolve_on_fput(newmount.mnt); | |
3737 | ret = PTR_ERR(file); | |
3738 | goto err_path; | |
3739 | } | |
3740 | file->f_mode |= FMODE_NEED_UNMOUNT; | |
3741 | ||
3742 | ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0); | |
3743 | if (ret >= 0) | |
3744 | fd_install(ret, file); | |
3745 | else | |
3746 | fput(file); | |
3747 | ||
3748 | err_path: | |
3749 | path_put(&newmount); | |
3750 | err_unlock: | |
3751 | mutex_unlock(&fc->uapi_mutex); | |
3752 | err_fsfd: | |
3753 | fdput(f); | |
3754 | return ret; | |
3755 | } | |
3756 | ||
3757 | /* | |
3758 | * Move a mount from one place to another. In combination with | |
3759 | * fsopen()/fsmount() this is used to install a new mount and in combination | |
3760 | * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy | |
3761 | * a mount subtree. | |
2db154b3 DH |
3762 | * |
3763 | * Note the flags value is a combination of MOVE_MOUNT_* flags. | |
3764 | */ | |
3765 | SYSCALL_DEFINE5(move_mount, | |
2658ce09 BD |
3766 | int, from_dfd, const char __user *, from_pathname, |
3767 | int, to_dfd, const char __user *, to_pathname, | |
2db154b3 DH |
3768 | unsigned int, flags) |
3769 | { | |
3770 | struct path from_path, to_path; | |
3771 | unsigned int lflags; | |
3772 | int ret = 0; | |
3773 | ||
3774 | if (!may_mount()) | |
3775 | return -EPERM; | |
3776 | ||
3777 | if (flags & ~MOVE_MOUNT__MASK) | |
3778 | return -EINVAL; | |
3779 | ||
3780 | /* If someone gives a pathname, they aren't permitted to move | |
3781 | * from an fd that requires unmount as we can't get at the flag | |
3782 | * to clear it afterwards. | |
3783 | */ | |
3784 | lflags = 0; | |
3785 | if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3786 | if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3787 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3788 | ||
3789 | ret = user_path_at(from_dfd, from_pathname, lflags, &from_path); | |
3790 | if (ret < 0) | |
3791 | return ret; | |
3792 | ||
3793 | lflags = 0; | |
3794 | if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW; | |
3795 | if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; | |
3796 | if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY; | |
3797 | ||
3798 | ret = user_path_at(to_dfd, to_pathname, lflags, &to_path); | |
3799 | if (ret < 0) | |
3800 | goto out_from; | |
3801 | ||
3802 | ret = security_move_mount(&from_path, &to_path); | |
3803 | if (ret < 0) | |
3804 | goto out_to; | |
3805 | ||
9ffb14ef PT |
3806 | if (flags & MOVE_MOUNT_SET_GROUP) |
3807 | ret = do_set_group(&from_path, &to_path); | |
3808 | else | |
3809 | ret = do_move_mount(&from_path, &to_path); | |
2db154b3 DH |
3810 | |
3811 | out_to: | |
3812 | path_put(&to_path); | |
3813 | out_from: | |
3814 | path_put(&from_path); | |
3815 | return ret; | |
3816 | } | |
3817 | ||
afac7cba AV |
3818 | /* |
3819 | * Return true if path is reachable from root | |
3820 | * | |
48a066e7 | 3821 | * namespace_sem or mount_lock is held |
afac7cba | 3822 | */ |
643822b4 | 3823 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
afac7cba AV |
3824 | const struct path *root) |
3825 | { | |
643822b4 | 3826 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
a73324da | 3827 | dentry = mnt->mnt_mountpoint; |
0714a533 | 3828 | mnt = mnt->mnt_parent; |
afac7cba | 3829 | } |
643822b4 | 3830 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
afac7cba AV |
3831 | } |
3832 | ||
640eb7e7 | 3833 | bool path_is_under(const struct path *path1, const struct path *path2) |
afac7cba | 3834 | { |
25ab4c9b | 3835 | bool res; |
48a066e7 | 3836 | read_seqlock_excl(&mount_lock); |
643822b4 | 3837 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
48a066e7 | 3838 | read_sequnlock_excl(&mount_lock); |
afac7cba AV |
3839 | return res; |
3840 | } | |
3841 | EXPORT_SYMBOL(path_is_under); | |
3842 | ||
1da177e4 LT |
3843 | /* |
3844 | * pivot_root Semantics: | |
3845 | * Moves the root file system of the current process to the directory put_old, | |
3846 | * makes new_root as the new root file system of the current process, and sets | |
3847 | * root/cwd of all processes which had them on the current root to new_root. | |
3848 | * | |
3849 | * Restrictions: | |
3850 | * The new_root and put_old must be directories, and must not be on the | |
3851 | * same file system as the current process root. The put_old must be | |
3852 | * underneath new_root, i.e. adding a non-zero number of /.. to the string | |
3853 | * pointed to by put_old must yield the same directory as new_root. No other | |
3854 | * file system may be mounted on put_old. After all, new_root is a mountpoint. | |
3855 | * | |
4a0d11fa | 3856 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
0c1bc6b8 | 3857 | * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives |
4a0d11fa NB |
3858 | * in this situation. |
3859 | * | |
1da177e4 LT |
3860 | * Notes: |
3861 | * - we don't move root/cwd if they are not at the root (reason: if something | |
3862 | * cared enough to change them, it's probably wrong to force them elsewhere) | |
3863 | * - it's okay to pick a root that isn't the root of a file system, e.g. | |
3864 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, | |
3865 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root | |
3866 | * first. | |
3867 | */ | |
3480b257 HC |
3868 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
3869 | const char __user *, put_old) | |
1da177e4 | 3870 | { |
2763d119 AV |
3871 | struct path new, old, root; |
3872 | struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; | |
84d17192 | 3873 | struct mountpoint *old_mp, *root_mp; |
1da177e4 LT |
3874 | int error; |
3875 | ||
9b40bc90 | 3876 | if (!may_mount()) |
1da177e4 LT |
3877 | return -EPERM; |
3878 | ||
ce6595a2 AV |
3879 | error = user_path_at(AT_FDCWD, new_root, |
3880 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new); | |
1da177e4 LT |
3881 | if (error) |
3882 | goto out0; | |
1da177e4 | 3883 | |
ce6595a2 AV |
3884 | error = user_path_at(AT_FDCWD, put_old, |
3885 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old); | |
1da177e4 LT |
3886 | if (error) |
3887 | goto out1; | |
3888 | ||
2d8f3038 | 3889 | error = security_sb_pivotroot(&old, &new); |
b12cea91 AV |
3890 | if (error) |
3891 | goto out2; | |
1da177e4 | 3892 | |
f7ad3c6b | 3893 | get_fs_root(current->fs, &root); |
84d17192 AV |
3894 | old_mp = lock_mount(&old); |
3895 | error = PTR_ERR(old_mp); | |
3896 | if (IS_ERR(old_mp)) | |
b12cea91 AV |
3897 | goto out3; |
3898 | ||
1da177e4 | 3899 | error = -EINVAL; |
419148da AV |
3900 | new_mnt = real_mount(new.mnt); |
3901 | root_mnt = real_mount(root.mnt); | |
84d17192 | 3902 | old_mnt = real_mount(old.mnt); |
2763d119 AV |
3903 | ex_parent = new_mnt->mnt_parent; |
3904 | root_parent = root_mnt->mnt_parent; | |
84d17192 | 3905 | if (IS_MNT_SHARED(old_mnt) || |
2763d119 AV |
3906 | IS_MNT_SHARED(ex_parent) || |
3907 | IS_MNT_SHARED(root_parent)) | |
b12cea91 | 3908 | goto out4; |
143c8c91 | 3909 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
b12cea91 | 3910 | goto out4; |
5ff9d8a6 EB |
3911 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
3912 | goto out4; | |
1da177e4 | 3913 | error = -ENOENT; |
f3da392e | 3914 | if (d_unlinked(new.dentry)) |
b12cea91 | 3915 | goto out4; |
1da177e4 | 3916 | error = -EBUSY; |
84d17192 | 3917 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
b12cea91 | 3918 | goto out4; /* loop, on the same file system */ |
1da177e4 | 3919 | error = -EINVAL; |
8c3ee42e | 3920 | if (root.mnt->mnt_root != root.dentry) |
b12cea91 | 3921 | goto out4; /* not a mountpoint */ |
676da58d | 3922 | if (!mnt_has_parent(root_mnt)) |
b12cea91 | 3923 | goto out4; /* not attached */ |
2d8f3038 | 3924 | if (new.mnt->mnt_root != new.dentry) |
b12cea91 | 3925 | goto out4; /* not a mountpoint */ |
676da58d | 3926 | if (!mnt_has_parent(new_mnt)) |
b12cea91 | 3927 | goto out4; /* not attached */ |
4ac91378 | 3928 | /* make sure we can reach put_old from new_root */ |
84d17192 | 3929 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
b12cea91 | 3930 | goto out4; |
0d082601 EB |
3931 | /* make certain new is below the root */ |
3932 | if (!is_path_reachable(new_mnt, new.dentry, &root)) | |
3933 | goto out4; | |
719ea2fb | 3934 | lock_mount_hash(); |
2763d119 AV |
3935 | umount_mnt(new_mnt); |
3936 | root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ | |
5ff9d8a6 EB |
3937 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
3938 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; | |
3939 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; | |
3940 | } | |
4ac91378 | 3941 | /* mount old root on put_old */ |
84d17192 | 3942 | attach_mnt(root_mnt, old_mnt, old_mp); |
4ac91378 | 3943 | /* mount new_root on / */ |
2763d119 AV |
3944 | attach_mnt(new_mnt, root_parent, root_mp); |
3945 | mnt_add_count(root_parent, -1); | |
6b3286ed | 3946 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
4fed655c EB |
3947 | /* A moved mount should not expire automatically */ |
3948 | list_del_init(&new_mnt->mnt_expire); | |
3895dbf8 | 3949 | put_mountpoint(root_mp); |
719ea2fb | 3950 | unlock_mount_hash(); |
2d8f3038 | 3951 | chroot_fs_refs(&root, &new); |
1da177e4 | 3952 | error = 0; |
b12cea91 | 3953 | out4: |
84d17192 | 3954 | unlock_mount(old_mp); |
2763d119 AV |
3955 | if (!error) |
3956 | mntput_no_expire(ex_parent); | |
b12cea91 | 3957 | out3: |
8c3ee42e | 3958 | path_put(&root); |
b12cea91 | 3959 | out2: |
2d8f3038 | 3960 | path_put(&old); |
1da177e4 | 3961 | out1: |
2d8f3038 | 3962 | path_put(&new); |
1da177e4 | 3963 | out0: |
1da177e4 | 3964 | return error; |
1da177e4 LT |
3965 | } |
3966 | ||
2a186721 CB |
3967 | static unsigned int recalc_flags(struct mount_kattr *kattr, struct mount *mnt) |
3968 | { | |
3969 | unsigned int flags = mnt->mnt.mnt_flags; | |
3970 | ||
3971 | /* flags to clear */ | |
3972 | flags &= ~kattr->attr_clr; | |
3973 | /* flags to raise */ | |
3974 | flags |= kattr->attr_set; | |
3975 | ||
3976 | return flags; | |
3977 | } | |
3978 | ||
9caccd41 CB |
3979 | static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
3980 | { | |
3981 | struct vfsmount *m = &mnt->mnt; | |
bd303368 | 3982 | struct user_namespace *fs_userns = m->mnt_sb->s_user_ns; |
9caccd41 CB |
3983 | |
3984 | if (!kattr->mnt_userns) | |
3985 | return 0; | |
3986 | ||
bd303368 CB |
3987 | /* |
3988 | * Creating an idmapped mount with the filesystem wide idmapping | |
3989 | * doesn't make sense so block that. We don't allow mushy semantics. | |
3990 | */ | |
3991 | if (kattr->mnt_userns == fs_userns) | |
3992 | return -EINVAL; | |
3993 | ||
9caccd41 CB |
3994 | /* |
3995 | * Once a mount has been idmapped we don't allow it to change its | |
3996 | * mapping. It makes things simpler and callers can just create | |
3997 | * another bind-mount they can idmap if they want to. | |
3998 | */ | |
bb49e9e7 | 3999 | if (is_idmapped_mnt(m)) |
9caccd41 CB |
4000 | return -EPERM; |
4001 | ||
4002 | /* The underlying filesystem doesn't support idmapped mounts yet. */ | |
4003 | if (!(m->mnt_sb->s_type->fs_flags & FS_ALLOW_IDMAP)) | |
4004 | return -EINVAL; | |
4005 | ||
4006 | /* We're not controlling the superblock. */ | |
bd303368 | 4007 | if (!ns_capable(fs_userns, CAP_SYS_ADMIN)) |
9caccd41 CB |
4008 | return -EPERM; |
4009 | ||
4010 | /* Mount has already been visible in the filesystem hierarchy. */ | |
4011 | if (!is_anon_ns(mnt->mnt_ns)) | |
4012 | return -EINVAL; | |
4013 | ||
4014 | return 0; | |
4015 | } | |
4016 | ||
a26f788b CB |
4017 | /** |
4018 | * mnt_allow_writers() - check whether the attribute change allows writers | |
4019 | * @kattr: the new mount attributes | |
4020 | * @mnt: the mount to which @kattr will be applied | |
4021 | * | |
4022 | * Check whether thew new mount attributes in @kattr allow concurrent writers. | |
4023 | * | |
4024 | * Return: true if writers need to be held, false if not | |
4025 | */ | |
4026 | static inline bool mnt_allow_writers(const struct mount_kattr *kattr, | |
4027 | const struct mount *mnt) | |
2a186721 | 4028 | { |
e1bbcd27 CB |
4029 | return (!(kattr->attr_set & MNT_READONLY) || |
4030 | (mnt->mnt.mnt_flags & MNT_READONLY)) && | |
4031 | !kattr->mnt_userns; | |
a26f788b | 4032 | } |
2a186721 | 4033 | |
87bb5b60 | 4034 | static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt) |
2a186721 | 4035 | { |
e257039f AV |
4036 | struct mount *m; |
4037 | int err; | |
2a186721 | 4038 | |
e257039f AV |
4039 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
4040 | if (!can_change_locked_flags(m, recalc_flags(kattr, m))) { | |
4041 | err = -EPERM; | |
4042 | break; | |
4043 | } | |
2a186721 | 4044 | |
87bb5b60 CB |
4045 | err = can_idmap_mount(kattr, m); |
4046 | if (err) | |
e257039f | 4047 | break; |
2a186721 | 4048 | |
e257039f AV |
4049 | if (!mnt_allow_writers(kattr, m)) { |
4050 | err = mnt_hold_writers(m); | |
4051 | if (err) | |
4052 | break; | |
2a186721 CB |
4053 | } |
4054 | ||
e257039f AV |
4055 | if (!kattr->recurse) |
4056 | return 0; | |
4057 | } | |
9caccd41 | 4058 | |
e257039f AV |
4059 | if (err) { |
4060 | struct mount *p; | |
2a186721 | 4061 | |
0014edae CB |
4062 | /* |
4063 | * If we had to call mnt_hold_writers() MNT_WRITE_HOLD will | |
4064 | * be set in @mnt_flags. The loop unsets MNT_WRITE_HOLD for all | |
4065 | * mounts and needs to take care to include the first mount. | |
4066 | */ | |
4067 | for (p = mnt; p; p = next_mnt(p, mnt)) { | |
e257039f AV |
4068 | /* If we had to hold writers unblock them. */ |
4069 | if (p->mnt.mnt_flags & MNT_WRITE_HOLD) | |
4070 | mnt_unhold_writers(p); | |
0014edae CB |
4071 | |
4072 | /* | |
4073 | * We're done once the first mount we changed got | |
4074 | * MNT_WRITE_HOLD unset. | |
4075 | */ | |
4076 | if (p == m) | |
4077 | break; | |
2a186721 | 4078 | } |
e257039f AV |
4079 | } |
4080 | return err; | |
2a186721 CB |
4081 | } |
4082 | ||
9caccd41 CB |
4083 | static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
4084 | { | |
bd303368 | 4085 | struct user_namespace *mnt_userns, *old_mnt_userns; |
9caccd41 CB |
4086 | |
4087 | if (!kattr->mnt_userns) | |
4088 | return; | |
4089 | ||
bd303368 CB |
4090 | /* |
4091 | * We're the only ones able to change the mount's idmapping. So | |
4092 | * mnt->mnt.mnt_userns is stable and we can retrieve it directly. | |
4093 | */ | |
4094 | old_mnt_userns = mnt->mnt.mnt_userns; | |
4095 | ||
9caccd41 CB |
4096 | mnt_userns = get_user_ns(kattr->mnt_userns); |
4097 | /* Pairs with smp_load_acquire() in mnt_user_ns(). */ | |
4098 | smp_store_release(&mnt->mnt.mnt_userns, mnt_userns); | |
bd303368 CB |
4099 | |
4100 | /* | |
4101 | * If this is an idmapped filesystem drop the reference we've taken | |
4102 | * in vfs_create_mount() before. | |
4103 | */ | |
4104 | if (!initial_idmapping(old_mnt_userns)) | |
4105 | put_user_ns(old_mnt_userns); | |
9caccd41 CB |
4106 | } |
4107 | ||
e257039f | 4108 | static void mount_setattr_commit(struct mount_kattr *kattr, struct mount *mnt) |
2a186721 | 4109 | { |
e257039f | 4110 | struct mount *m; |
2a186721 | 4111 | |
e257039f AV |
4112 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
4113 | unsigned int flags; | |
2a186721 | 4114 | |
e257039f AV |
4115 | do_idmap_mount(kattr, m); |
4116 | flags = recalc_flags(kattr, m); | |
4117 | WRITE_ONCE(m->mnt.mnt_flags, flags); | |
2a186721 | 4118 | |
03b6abee CB |
4119 | /* If we had to hold writers unblock them. */ |
4120 | if (m->mnt.mnt_flags & MNT_WRITE_HOLD) | |
2a186721 CB |
4121 | mnt_unhold_writers(m); |
4122 | ||
e257039f | 4123 | if (kattr->propagation) |
2a186721 | 4124 | change_mnt_propagation(m, kattr->propagation); |
e257039f | 4125 | if (!kattr->recurse) |
2a186721 | 4126 | break; |
e257039f AV |
4127 | } |
4128 | touch_mnt_namespace(mnt->mnt_ns); | |
2a186721 CB |
4129 | } |
4130 | ||
4131 | static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) | |
4132 | { | |
87bb5b60 | 4133 | struct mount *mnt = real_mount(path->mnt); |
2a186721 CB |
4134 | int err = 0; |
4135 | ||
4136 | if (path->dentry != mnt->mnt.mnt_root) | |
4137 | return -EINVAL; | |
4138 | ||
4139 | if (kattr->propagation) { | |
4140 | /* | |
4141 | * Only take namespace_lock() if we're actually changing | |
4142 | * propagation. | |
4143 | */ | |
4144 | namespace_lock(); | |
4145 | if (kattr->propagation == MS_SHARED) { | |
4146 | err = invent_group_ids(mnt, kattr->recurse); | |
4147 | if (err) { | |
4148 | namespace_unlock(); | |
4149 | return err; | |
4150 | } | |
4151 | } | |
4152 | } | |
4153 | ||
87bb5b60 | 4154 | err = -EINVAL; |
2a186721 CB |
4155 | lock_mount_hash(); |
4156 | ||
87bb5b60 CB |
4157 | /* Ensure that this isn't anything purely vfs internal. */ |
4158 | if (!is_mounted(&mnt->mnt)) | |
4159 | goto out; | |
4160 | ||
2a186721 | 4161 | /* |
87bb5b60 CB |
4162 | * If this is an attached mount make sure it's located in the callers |
4163 | * mount namespace. If it's not don't let the caller interact with it. | |
4164 | * If this is a detached mount make sure it has an anonymous mount | |
4165 | * namespace attached to it, i.e. we've created it via OPEN_TREE_CLONE. | |
2a186721 | 4166 | */ |
87bb5b60 CB |
4167 | if (!(mnt_has_parent(mnt) ? check_mnt(mnt) : is_anon_ns(mnt->mnt_ns))) |
4168 | goto out; | |
2a186721 | 4169 | |
87bb5b60 CB |
4170 | /* |
4171 | * First, we get the mount tree in a shape where we can change mount | |
4172 | * properties without failure. If we succeeded to do so we commit all | |
4173 | * changes and if we failed we clean up. | |
4174 | */ | |
4175 | err = mount_setattr_prepare(kattr, mnt); | |
e257039f AV |
4176 | if (!err) |
4177 | mount_setattr_commit(kattr, mnt); | |
2a186721 | 4178 | |
87bb5b60 | 4179 | out: |
2a186721 CB |
4180 | unlock_mount_hash(); |
4181 | ||
4182 | if (kattr->propagation) { | |
4183 | namespace_unlock(); | |
4184 | if (err) | |
4185 | cleanup_group_ids(mnt, NULL); | |
4186 | } | |
4187 | ||
4188 | return err; | |
4189 | } | |
4190 | ||
9caccd41 CB |
4191 | static int build_mount_idmapped(const struct mount_attr *attr, size_t usize, |
4192 | struct mount_kattr *kattr, unsigned int flags) | |
4193 | { | |
4194 | int err = 0; | |
4195 | struct ns_common *ns; | |
4196 | struct user_namespace *mnt_userns; | |
4197 | struct file *file; | |
4198 | ||
4199 | if (!((attr->attr_set | attr->attr_clr) & MOUNT_ATTR_IDMAP)) | |
4200 | return 0; | |
4201 | ||
4202 | /* | |
4203 | * We currently do not support clearing an idmapped mount. If this ever | |
4204 | * is a use-case we can revisit this but for now let's keep it simple | |
4205 | * and not allow it. | |
4206 | */ | |
4207 | if (attr->attr_clr & MOUNT_ATTR_IDMAP) | |
4208 | return -EINVAL; | |
4209 | ||
4210 | if (attr->userns_fd > INT_MAX) | |
4211 | return -EINVAL; | |
4212 | ||
4213 | file = fget(attr->userns_fd); | |
4214 | if (!file) | |
4215 | return -EBADF; | |
4216 | ||
4217 | if (!proc_ns_file(file)) { | |
4218 | err = -EINVAL; | |
4219 | goto out_fput; | |
4220 | } | |
4221 | ||
4222 | ns = get_proc_ns(file_inode(file)); | |
4223 | if (ns->ops->type != CLONE_NEWUSER) { | |
4224 | err = -EINVAL; | |
4225 | goto out_fput; | |
4226 | } | |
4227 | ||
4228 | /* | |
bd303368 CB |
4229 | * The initial idmapping cannot be used to create an idmapped |
4230 | * mount. We use the initial idmapping as an indicator of a mount | |
4231 | * that is not idmapped. It can simply be passed into helpers that | |
4232 | * are aware of idmapped mounts as a convenient shortcut. A user | |
4233 | * can just create a dedicated identity mapping to achieve the same | |
4234 | * result. | |
9caccd41 CB |
4235 | */ |
4236 | mnt_userns = container_of(ns, struct user_namespace, ns); | |
bd303368 | 4237 | if (initial_idmapping(mnt_userns)) { |
9caccd41 CB |
4238 | err = -EPERM; |
4239 | goto out_fput; | |
4240 | } | |
4241 | kattr->mnt_userns = get_user_ns(mnt_userns); | |
4242 | ||
4243 | out_fput: | |
4244 | fput(file); | |
4245 | return err; | |
4246 | } | |
4247 | ||
4248 | static int build_mount_kattr(const struct mount_attr *attr, size_t usize, | |
2a186721 CB |
4249 | struct mount_kattr *kattr, unsigned int flags) |
4250 | { | |
4251 | unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; | |
4252 | ||
4253 | if (flags & AT_NO_AUTOMOUNT) | |
4254 | lookup_flags &= ~LOOKUP_AUTOMOUNT; | |
4255 | if (flags & AT_SYMLINK_NOFOLLOW) | |
4256 | lookup_flags &= ~LOOKUP_FOLLOW; | |
4257 | if (flags & AT_EMPTY_PATH) | |
4258 | lookup_flags |= LOOKUP_EMPTY; | |
4259 | ||
4260 | *kattr = (struct mount_kattr) { | |
4261 | .lookup_flags = lookup_flags, | |
4262 | .recurse = !!(flags & AT_RECURSIVE), | |
4263 | }; | |
4264 | ||
4265 | if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS) | |
4266 | return -EINVAL; | |
4267 | if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1) | |
4268 | return -EINVAL; | |
4269 | kattr->propagation = attr->propagation; | |
4270 | ||
4271 | if ((attr->attr_set | attr->attr_clr) & ~MOUNT_SETATTR_VALID_FLAGS) | |
4272 | return -EINVAL; | |
4273 | ||
2a186721 CB |
4274 | kattr->attr_set = attr_flags_to_mnt_flags(attr->attr_set); |
4275 | kattr->attr_clr = attr_flags_to_mnt_flags(attr->attr_clr); | |
4276 | ||
4277 | /* | |
4278 | * Since the MOUNT_ATTR_<atime> values are an enum, not a bitmap, | |
4279 | * users wanting to transition to a different atime setting cannot | |
4280 | * simply specify the atime setting in @attr_set, but must also | |
4281 | * specify MOUNT_ATTR__ATIME in the @attr_clr field. | |
4282 | * So ensure that MOUNT_ATTR__ATIME can't be partially set in | |
4283 | * @attr_clr and that @attr_set can't have any atime bits set if | |
4284 | * MOUNT_ATTR__ATIME isn't set in @attr_clr. | |
4285 | */ | |
4286 | if (attr->attr_clr & MOUNT_ATTR__ATIME) { | |
4287 | if ((attr->attr_clr & MOUNT_ATTR__ATIME) != MOUNT_ATTR__ATIME) | |
4288 | return -EINVAL; | |
4289 | ||
4290 | /* | |
4291 | * Clear all previous time settings as they are mutually | |
4292 | * exclusive. | |
4293 | */ | |
4294 | kattr->attr_clr |= MNT_RELATIME | MNT_NOATIME; | |
4295 | switch (attr->attr_set & MOUNT_ATTR__ATIME) { | |
4296 | case MOUNT_ATTR_RELATIME: | |
4297 | kattr->attr_set |= MNT_RELATIME; | |
4298 | break; | |
4299 | case MOUNT_ATTR_NOATIME: | |
4300 | kattr->attr_set |= MNT_NOATIME; | |
4301 | break; | |
4302 | case MOUNT_ATTR_STRICTATIME: | |
4303 | break; | |
4304 | default: | |
4305 | return -EINVAL; | |
4306 | } | |
4307 | } else { | |
4308 | if (attr->attr_set & MOUNT_ATTR__ATIME) | |
4309 | return -EINVAL; | |
4310 | } | |
4311 | ||
9caccd41 CB |
4312 | return build_mount_idmapped(attr, usize, kattr, flags); |
4313 | } | |
4314 | ||
4315 | static void finish_mount_kattr(struct mount_kattr *kattr) | |
4316 | { | |
4317 | put_user_ns(kattr->mnt_userns); | |
4318 | kattr->mnt_userns = NULL; | |
2a186721 CB |
4319 | } |
4320 | ||
4321 | SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path, | |
4322 | unsigned int, flags, struct mount_attr __user *, uattr, | |
4323 | size_t, usize) | |
4324 | { | |
4325 | int err; | |
4326 | struct path target; | |
4327 | struct mount_attr attr; | |
4328 | struct mount_kattr kattr; | |
4329 | ||
4330 | BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0); | |
4331 | ||
4332 | if (flags & ~(AT_EMPTY_PATH | | |
4333 | AT_RECURSIVE | | |
4334 | AT_SYMLINK_NOFOLLOW | | |
4335 | AT_NO_AUTOMOUNT)) | |
4336 | return -EINVAL; | |
4337 | ||
4338 | if (unlikely(usize > PAGE_SIZE)) | |
4339 | return -E2BIG; | |
4340 | if (unlikely(usize < MOUNT_ATTR_SIZE_VER0)) | |
4341 | return -EINVAL; | |
4342 | ||
4343 | if (!may_mount()) | |
4344 | return -EPERM; | |
4345 | ||
4346 | err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize); | |
4347 | if (err) | |
4348 | return err; | |
4349 | ||
4350 | /* Don't bother walking through the mounts if this is a nop. */ | |
4351 | if (attr.attr_set == 0 && | |
4352 | attr.attr_clr == 0 && | |
4353 | attr.propagation == 0) | |
4354 | return 0; | |
4355 | ||
9caccd41 | 4356 | err = build_mount_kattr(&attr, usize, &kattr, flags); |
2a186721 CB |
4357 | if (err) |
4358 | return err; | |
4359 | ||
4360 | err = user_path_at(dfd, path, kattr.lookup_flags, &target); | |
012e3322 CB |
4361 | if (!err) { |
4362 | err = do_mount_setattr(&target, &kattr); | |
4363 | path_put(&target); | |
4364 | } | |
9caccd41 | 4365 | finish_mount_kattr(&kattr); |
2a186721 CB |
4366 | return err; |
4367 | } | |
4368 | ||
1da177e4 LT |
4369 | static void __init init_mount_tree(void) |
4370 | { | |
4371 | struct vfsmount *mnt; | |
74e83122 | 4372 | struct mount *m; |
6b3286ed | 4373 | struct mnt_namespace *ns; |
ac748a09 | 4374 | struct path root; |
1da177e4 | 4375 | |
fd3e007f | 4376 | mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL); |
1da177e4 LT |
4377 | if (IS_ERR(mnt)) |
4378 | panic("Can't create rootfs"); | |
b3e19d92 | 4379 | |
74e83122 | 4380 | ns = alloc_mnt_ns(&init_user_ns, false); |
3b22edc5 | 4381 | if (IS_ERR(ns)) |
1da177e4 | 4382 | panic("Can't allocate initial namespace"); |
74e83122 AV |
4383 | m = real_mount(mnt); |
4384 | m->mnt_ns = ns; | |
4385 | ns->root = m; | |
4386 | ns->mounts = 1; | |
4387 | list_add(&m->mnt_list, &ns->list); | |
6b3286ed KK |
4388 | init_task.nsproxy->mnt_ns = ns; |
4389 | get_mnt_ns(ns); | |
4390 | ||
be08d6d2 AV |
4391 | root.mnt = mnt; |
4392 | root.dentry = mnt->mnt_root; | |
da362b09 | 4393 | mnt->mnt_flags |= MNT_LOCKED; |
ac748a09 JB |
4394 | |
4395 | set_fs_pwd(current->fs, &root); | |
4396 | set_fs_root(current->fs, &root); | |
1da177e4 LT |
4397 | } |
4398 | ||
74bf17cf | 4399 | void __init mnt_init(void) |
1da177e4 | 4400 | { |
15a67dd8 | 4401 | int err; |
1da177e4 | 4402 | |
7d6fec45 | 4403 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
79f6540b | 4404 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); |
1da177e4 | 4405 | |
0818bf27 | 4406 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
38129a13 | 4407 | sizeof(struct hlist_head), |
0818bf27 | 4408 | mhash_entries, 19, |
3d375d78 | 4409 | HASH_ZERO, |
0818bf27 AV |
4410 | &m_hash_shift, &m_hash_mask, 0, 0); |
4411 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", | |
4412 | sizeof(struct hlist_head), | |
4413 | mphash_entries, 19, | |
3d375d78 | 4414 | HASH_ZERO, |
0818bf27 | 4415 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
1da177e4 | 4416 | |
84d17192 | 4417 | if (!mount_hashtable || !mountpoint_hashtable) |
1da177e4 LT |
4418 | panic("Failed to allocate mount hash table\n"); |
4419 | ||
4b93dc9b TH |
4420 | kernfs_init(); |
4421 | ||
15a67dd8 RD |
4422 | err = sysfs_init(); |
4423 | if (err) | |
4424 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", | |
8e24eea7 | 4425 | __func__, err); |
00d26666 GKH |
4426 | fs_kobj = kobject_create_and_add("fs", NULL); |
4427 | if (!fs_kobj) | |
8e24eea7 | 4428 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
037f11b4 | 4429 | shmem_init(); |
1da177e4 LT |
4430 | init_rootfs(); |
4431 | init_mount_tree(); | |
4432 | } | |
4433 | ||
616511d0 | 4434 | void put_mnt_ns(struct mnt_namespace *ns) |
1da177e4 | 4435 | { |
1a7b8969 | 4436 | if (!refcount_dec_and_test(&ns->ns.count)) |
616511d0 | 4437 | return; |
7b00ed6f | 4438 | drop_collected_mounts(&ns->root->mnt); |
771b1371 | 4439 | free_mnt_ns(ns); |
1da177e4 | 4440 | } |
9d412a43 | 4441 | |
d911b458 | 4442 | struct vfsmount *kern_mount(struct file_system_type *type) |
9d412a43 | 4443 | { |
423e0ab0 | 4444 | struct vfsmount *mnt; |
d911b458 | 4445 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
423e0ab0 TC |
4446 | if (!IS_ERR(mnt)) { |
4447 | /* | |
4448 | * it is a longterm mount, don't release mnt until | |
4449 | * we unmount before file sys is unregistered | |
4450 | */ | |
f7a99c5b | 4451 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
423e0ab0 TC |
4452 | } |
4453 | return mnt; | |
9d412a43 | 4454 | } |
d911b458 | 4455 | EXPORT_SYMBOL_GPL(kern_mount); |
423e0ab0 TC |
4456 | |
4457 | void kern_unmount(struct vfsmount *mnt) | |
4458 | { | |
4459 | /* release long term mount so mount point can be released */ | |
4460 | if (!IS_ERR_OR_NULL(mnt)) { | |
f7a99c5b | 4461 | real_mount(mnt)->mnt_ns = NULL; |
48a066e7 | 4462 | synchronize_rcu(); /* yecchhh... */ |
423e0ab0 TC |
4463 | mntput(mnt); |
4464 | } | |
4465 | } | |
4466 | EXPORT_SYMBOL(kern_unmount); | |
02125a82 | 4467 | |
df820f8d MS |
4468 | void kern_unmount_array(struct vfsmount *mnt[], unsigned int num) |
4469 | { | |
4470 | unsigned int i; | |
4471 | ||
4472 | for (i = 0; i < num; i++) | |
4473 | if (mnt[i]) | |
4474 | real_mount(mnt[i])->mnt_ns = NULL; | |
4475 | synchronize_rcu_expedited(); | |
4476 | for (i = 0; i < num; i++) | |
4477 | mntput(mnt[i]); | |
4478 | } | |
4479 | EXPORT_SYMBOL(kern_unmount_array); | |
4480 | ||
02125a82 AV |
4481 | bool our_mnt(struct vfsmount *mnt) |
4482 | { | |
143c8c91 | 4483 | return check_mnt(real_mount(mnt)); |
02125a82 | 4484 | } |
8823c079 | 4485 | |
3151527e EB |
4486 | bool current_chrooted(void) |
4487 | { | |
4488 | /* Does the current process have a non-standard root */ | |
4489 | struct path ns_root; | |
4490 | struct path fs_root; | |
4491 | bool chrooted; | |
4492 | ||
4493 | /* Find the namespace root */ | |
4494 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; | |
4495 | ns_root.dentry = ns_root.mnt->mnt_root; | |
4496 | path_get(&ns_root); | |
4497 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) | |
4498 | ; | |
4499 | ||
4500 | get_fs_root(current->fs, &fs_root); | |
4501 | ||
4502 | chrooted = !path_equal(&fs_root, &ns_root); | |
4503 | ||
4504 | path_put(&fs_root); | |
4505 | path_put(&ns_root); | |
4506 | ||
4507 | return chrooted; | |
4508 | } | |
4509 | ||
132e4608 DH |
4510 | static bool mnt_already_visible(struct mnt_namespace *ns, |
4511 | const struct super_block *sb, | |
8654df4e | 4512 | int *new_mnt_flags) |
87a8ebd6 | 4513 | { |
8c6cf9cc | 4514 | int new_flags = *new_mnt_flags; |
87a8ebd6 | 4515 | struct mount *mnt; |
e51db735 | 4516 | bool visible = false; |
87a8ebd6 | 4517 | |
44bb4385 | 4518 | down_read(&namespace_sem); |
9f6c61f9 | 4519 | lock_ns_list(ns); |
87a8ebd6 | 4520 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
e51db735 | 4521 | struct mount *child; |
77b1a97d EB |
4522 | int mnt_flags; |
4523 | ||
9f6c61f9 MS |
4524 | if (mnt_is_cursor(mnt)) |
4525 | continue; | |
4526 | ||
132e4608 | 4527 | if (mnt->mnt.mnt_sb->s_type != sb->s_type) |
e51db735 EB |
4528 | continue; |
4529 | ||
7e96c1b0 EB |
4530 | /* This mount is not fully visible if it's root directory |
4531 | * is not the root directory of the filesystem. | |
4532 | */ | |
4533 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) | |
4534 | continue; | |
4535 | ||
a1935c17 | 4536 | /* A local view of the mount flags */ |
77b1a97d | 4537 | mnt_flags = mnt->mnt.mnt_flags; |
77b1a97d | 4538 | |
695e9df0 | 4539 | /* Don't miss readonly hidden in the superblock flags */ |
bc98a42c | 4540 | if (sb_rdonly(mnt->mnt.mnt_sb)) |
695e9df0 EB |
4541 | mnt_flags |= MNT_LOCK_READONLY; |
4542 | ||
8c6cf9cc EB |
4543 | /* Verify the mount flags are equal to or more permissive |
4544 | * than the proposed new mount. | |
4545 | */ | |
77b1a97d | 4546 | if ((mnt_flags & MNT_LOCK_READONLY) && |
8c6cf9cc EB |
4547 | !(new_flags & MNT_READONLY)) |
4548 | continue; | |
77b1a97d EB |
4549 | if ((mnt_flags & MNT_LOCK_ATIME) && |
4550 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) | |
8c6cf9cc EB |
4551 | continue; |
4552 | ||
ceeb0e5d EB |
4553 | /* This mount is not fully visible if there are any |
4554 | * locked child mounts that cover anything except for | |
4555 | * empty directories. | |
e51db735 EB |
4556 | */ |
4557 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { | |
4558 | struct inode *inode = child->mnt_mountpoint->d_inode; | |
ceeb0e5d | 4559 | /* Only worry about locked mounts */ |
d71ed6c9 | 4560 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
ceeb0e5d | 4561 | continue; |
7236c85e EB |
4562 | /* Is the directory permanetly empty? */ |
4563 | if (!is_empty_dir_inode(inode)) | |
e51db735 | 4564 | goto next; |
87a8ebd6 | 4565 | } |
8c6cf9cc | 4566 | /* Preserve the locked attributes */ |
77b1a97d | 4567 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
77b1a97d | 4568 | MNT_LOCK_ATIME); |
e51db735 EB |
4569 | visible = true; |
4570 | goto found; | |
4571 | next: ; | |
87a8ebd6 | 4572 | } |
e51db735 | 4573 | found: |
9f6c61f9 | 4574 | unlock_ns_list(ns); |
44bb4385 | 4575 | up_read(&namespace_sem); |
e51db735 | 4576 | return visible; |
87a8ebd6 EB |
4577 | } |
4578 | ||
132e4608 | 4579 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags) |
8654df4e | 4580 | { |
a1935c17 | 4581 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
8654df4e EB |
4582 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
4583 | unsigned long s_iflags; | |
4584 | ||
4585 | if (ns->user_ns == &init_user_ns) | |
4586 | return false; | |
4587 | ||
4588 | /* Can this filesystem be too revealing? */ | |
132e4608 | 4589 | s_iflags = sb->s_iflags; |
8654df4e EB |
4590 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
4591 | return false; | |
4592 | ||
a1935c17 EB |
4593 | if ((s_iflags & required_iflags) != required_iflags) { |
4594 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", | |
4595 | required_iflags); | |
4596 | return true; | |
4597 | } | |
4598 | ||
132e4608 | 4599 | return !mnt_already_visible(ns, sb, new_mnt_flags); |
8654df4e EB |
4600 | } |
4601 | ||
380cf5ba AL |
4602 | bool mnt_may_suid(struct vfsmount *mnt) |
4603 | { | |
4604 | /* | |
4605 | * Foreign mounts (accessed via fchdir or through /proc | |
4606 | * symlinks) are always treated as if they are nosuid. This | |
4607 | * prevents namespaces from trusting potentially unsafe | |
4608 | * suid/sgid bits, file caps, or security labels that originate | |
4609 | * in other namespaces. | |
4610 | */ | |
4611 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && | |
4612 | current_in_userns(mnt->mnt_sb->s_user_ns); | |
4613 | } | |
4614 | ||
64964528 | 4615 | static struct ns_common *mntns_get(struct task_struct *task) |
8823c079 | 4616 | { |
58be2825 | 4617 | struct ns_common *ns = NULL; |
8823c079 EB |
4618 | struct nsproxy *nsproxy; |
4619 | ||
728dba3a EB |
4620 | task_lock(task); |
4621 | nsproxy = task->nsproxy; | |
8823c079 | 4622 | if (nsproxy) { |
58be2825 AV |
4623 | ns = &nsproxy->mnt_ns->ns; |
4624 | get_mnt_ns(to_mnt_ns(ns)); | |
8823c079 | 4625 | } |
728dba3a | 4626 | task_unlock(task); |
8823c079 EB |
4627 | |
4628 | return ns; | |
4629 | } | |
4630 | ||
64964528 | 4631 | static void mntns_put(struct ns_common *ns) |
8823c079 | 4632 | { |
58be2825 | 4633 | put_mnt_ns(to_mnt_ns(ns)); |
8823c079 EB |
4634 | } |
4635 | ||
f2a8d52e | 4636 | static int mntns_install(struct nsset *nsset, struct ns_common *ns) |
8823c079 | 4637 | { |
f2a8d52e CB |
4638 | struct nsproxy *nsproxy = nsset->nsproxy; |
4639 | struct fs_struct *fs = nsset->fs; | |
4f757f3c | 4640 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns; |
f2a8d52e | 4641 | struct user_namespace *user_ns = nsset->cred->user_ns; |
8823c079 | 4642 | struct path root; |
4f757f3c | 4643 | int err; |
8823c079 | 4644 | |
0c55cfc4 | 4645 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
f2a8d52e CB |
4646 | !ns_capable(user_ns, CAP_SYS_CHROOT) || |
4647 | !ns_capable(user_ns, CAP_SYS_ADMIN)) | |
ae11e0f1 | 4648 | return -EPERM; |
8823c079 | 4649 | |
74e83122 AV |
4650 | if (is_anon_ns(mnt_ns)) |
4651 | return -EINVAL; | |
4652 | ||
8823c079 EB |
4653 | if (fs->users != 1) |
4654 | return -EINVAL; | |
4655 | ||
4656 | get_mnt_ns(mnt_ns); | |
4f757f3c | 4657 | old_mnt_ns = nsproxy->mnt_ns; |
8823c079 EB |
4658 | nsproxy->mnt_ns = mnt_ns; |
4659 | ||
4660 | /* Find the root */ | |
4f757f3c AV |
4661 | err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt, |
4662 | "/", LOOKUP_DOWN, &root); | |
4663 | if (err) { | |
4664 | /* revert to old namespace */ | |
4665 | nsproxy->mnt_ns = old_mnt_ns; | |
4666 | put_mnt_ns(mnt_ns); | |
4667 | return err; | |
4668 | } | |
8823c079 | 4669 | |
4068367c AV |
4670 | put_mnt_ns(old_mnt_ns); |
4671 | ||
8823c079 EB |
4672 | /* Update the pwd and root */ |
4673 | set_fs_pwd(fs, &root); | |
4674 | set_fs_root(fs, &root); | |
4675 | ||
4676 | path_put(&root); | |
4677 | return 0; | |
4678 | } | |
4679 | ||
bcac25a5 AV |
4680 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
4681 | { | |
4682 | return to_mnt_ns(ns)->user_ns; | |
4683 | } | |
4684 | ||
8823c079 EB |
4685 | const struct proc_ns_operations mntns_operations = { |
4686 | .name = "mnt", | |
4687 | .type = CLONE_NEWNS, | |
4688 | .get = mntns_get, | |
4689 | .put = mntns_put, | |
4690 | .install = mntns_install, | |
bcac25a5 | 4691 | .owner = mntns_owner, |
8823c079 | 4692 | }; |
ab171b95 LC |
4693 | |
4694 | #ifdef CONFIG_SYSCTL | |
4695 | static struct ctl_table fs_namespace_sysctls[] = { | |
4696 | { | |
4697 | .procname = "mount-max", | |
4698 | .data = &sysctl_mount_max, | |
4699 | .maxlen = sizeof(unsigned int), | |
4700 | .mode = 0644, | |
4701 | .proc_handler = proc_dointvec_minmax, | |
4702 | .extra1 = SYSCTL_ONE, | |
4703 | }, | |
4704 | { } | |
4705 | }; | |
4706 | ||
4707 | static int __init init_fs_namespace_sysctls(void) | |
4708 | { | |
4709 | register_sysctl_init("fs", fs_namespace_sysctls); | |
4710 | return 0; | |
4711 | } | |
4712 | fs_initcall(init_fs_namespace_sysctls); | |
4713 | ||
4714 | #endif /* CONFIG_SYSCTL */ |