Commit | Line | Data |
---|---|---|
e9be9d5e MS |
1 | /* |
2 | * | |
3 | * Copyright (C) 2011 Novell Inc. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License version 2 as published by | |
7 | * the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/fs.h> | |
11 | #include <linux/namei.h> | |
cf9a6784 | 12 | #include <linux/pagemap.h> |
e9be9d5e MS |
13 | #include <linux/xattr.h> |
14 | #include <linux/security.h> | |
15 | #include <linux/mount.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/parser.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/sched.h> | |
cc259639 | 20 | #include <linux/statfs.h> |
f45827e8 | 21 | #include <linux/seq_file.h> |
d837a49b | 22 | #include <linux/posix_acl_xattr.h> |
e9be9d5e MS |
23 | #include "overlayfs.h" |
24 | ||
25 | MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
26 | MODULE_DESCRIPTION("Overlay filesystem"); | |
27 | MODULE_LICENSE("GPL"); | |
28 | ||
f45827e8 EZ |
29 | struct ovl_config { |
30 | char *lowerdir; | |
31 | char *upperdir; | |
32 | char *workdir; | |
8d3095f4 | 33 | bool default_permissions; |
f45827e8 EZ |
34 | }; |
35 | ||
e9be9d5e MS |
36 | /* private information held for overlayfs's superblock */ |
37 | struct ovl_fs { | |
38 | struct vfsmount *upper_mnt; | |
dd662667 MS |
39 | unsigned numlower; |
40 | struct vfsmount **lower_mnt; | |
e9be9d5e | 41 | struct dentry *workdir; |
cc259639 | 42 | long lower_namelen; |
f45827e8 EZ |
43 | /* pathnames of lower and upper dirs, for show_options */ |
44 | struct ovl_config config; | |
3fe6e52f AM |
45 | /* creds of process who forced instantiation of super block */ |
46 | const struct cred *creator_cred; | |
e9be9d5e MS |
47 | }; |
48 | ||
49 | struct ovl_dir_cache; | |
50 | ||
51 | /* private information held for every overlayfs dentry */ | |
52 | struct ovl_entry { | |
53 | struct dentry *__upperdentry; | |
e9be9d5e MS |
54 | struct ovl_dir_cache *cache; |
55 | union { | |
56 | struct { | |
57 | u64 version; | |
58 | bool opaque; | |
59 | }; | |
60 | struct rcu_head rcu; | |
61 | }; | |
dd662667 MS |
62 | unsigned numlower; |
63 | struct path lowerstack[]; | |
e9be9d5e MS |
64 | }; |
65 | ||
a78d9f0d MS |
66 | #define OVL_MAX_STACK 500 |
67 | ||
dd662667 MS |
68 | static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) |
69 | { | |
70 | return oe->numlower ? oe->lowerstack[0].dentry : NULL; | |
71 | } | |
e9be9d5e MS |
72 | |
73 | enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
74 | { | |
75 | struct ovl_entry *oe = dentry->d_fsdata; | |
1afaba1e | 76 | enum ovl_path_type type = 0; |
e9be9d5e MS |
77 | |
78 | if (oe->__upperdentry) { | |
1afaba1e MS |
79 | type = __OVL_PATH_UPPER; |
80 | ||
45d11738 KK |
81 | /* |
82 | * Non-dir dentry can hold lower dentry from previous | |
83 | * location. Its purity depends only on opaque flag. | |
84 | */ | |
85 | if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode)) | |
86 | type |= __OVL_PATH_MERGE; | |
87 | else if (!oe->opaque) | |
1afaba1e | 88 | type |= __OVL_PATH_PURE; |
9d7459d8 MS |
89 | } else { |
90 | if (oe->numlower > 1) | |
91 | type |= __OVL_PATH_MERGE; | |
e9be9d5e | 92 | } |
1afaba1e | 93 | return type; |
e9be9d5e MS |
94 | } |
95 | ||
96 | static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) | |
97 | { | |
71d50928 | 98 | return lockless_dereference(oe->__upperdentry); |
e9be9d5e MS |
99 | } |
100 | ||
101 | void ovl_path_upper(struct dentry *dentry, struct path *path) | |
102 | { | |
103 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
104 | struct ovl_entry *oe = dentry->d_fsdata; | |
105 | ||
106 | path->mnt = ofs->upper_mnt; | |
107 | path->dentry = ovl_upperdentry_dereference(oe); | |
108 | } | |
109 | ||
110 | enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
111 | { | |
e9be9d5e MS |
112 | enum ovl_path_type type = ovl_path_type(dentry); |
113 | ||
1afaba1e | 114 | if (!OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
115 | ovl_path_lower(dentry, path); |
116 | else | |
117 | ovl_path_upper(dentry, path); | |
118 | ||
119 | return type; | |
120 | } | |
121 | ||
122 | struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
123 | { | |
124 | struct ovl_entry *oe = dentry->d_fsdata; | |
125 | ||
126 | return ovl_upperdentry_dereference(oe); | |
127 | } | |
128 | ||
129 | struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
130 | { | |
131 | struct ovl_entry *oe = dentry->d_fsdata; | |
132 | ||
dd662667 | 133 | return __ovl_dentry_lower(oe); |
e9be9d5e MS |
134 | } |
135 | ||
136 | struct dentry *ovl_dentry_real(struct dentry *dentry) | |
137 | { | |
138 | struct ovl_entry *oe = dentry->d_fsdata; | |
139 | struct dentry *realdentry; | |
140 | ||
141 | realdentry = ovl_upperdentry_dereference(oe); | |
142 | if (!realdentry) | |
dd662667 | 143 | realdentry = __ovl_dentry_lower(oe); |
e9be9d5e MS |
144 | |
145 | return realdentry; | |
146 | } | |
147 | ||
39b681f8 MS |
148 | static void ovl_inode_init(struct inode *inode, struct inode *realinode, |
149 | bool is_upper) | |
e9be9d5e | 150 | { |
39b681f8 MS |
151 | WRITE_ONCE(inode->i_private, (unsigned long) realinode | |
152 | (is_upper ? OVL_ISUPPER_MASK : 0)); | |
39a25b2b VG |
153 | } |
154 | ||
8d3095f4 MS |
155 | struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, |
156 | bool is_upper) | |
157 | { | |
158 | if (is_upper) { | |
159 | struct ovl_fs *ofs = inode->i_sb->s_fs_info; | |
160 | ||
161 | return ofs->upper_mnt; | |
162 | } else { | |
163 | return oe->numlower ? oe->lowerstack[0].mnt : NULL; | |
164 | } | |
165 | } | |
166 | ||
e9be9d5e MS |
167 | struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) |
168 | { | |
169 | struct ovl_entry *oe = dentry->d_fsdata; | |
170 | ||
171 | return oe->cache; | |
172 | } | |
173 | ||
174 | void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) | |
175 | { | |
176 | struct ovl_entry *oe = dentry->d_fsdata; | |
177 | ||
178 | oe->cache = cache; | |
179 | } | |
180 | ||
181 | void ovl_path_lower(struct dentry *dentry, struct path *path) | |
182 | { | |
e9be9d5e MS |
183 | struct ovl_entry *oe = dentry->d_fsdata; |
184 | ||
dd662667 | 185 | *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; |
e9be9d5e MS |
186 | } |
187 | ||
188 | int ovl_want_write(struct dentry *dentry) | |
189 | { | |
190 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
191 | return mnt_want_write(ofs->upper_mnt); | |
192 | } | |
193 | ||
194 | void ovl_drop_write(struct dentry *dentry) | |
195 | { | |
196 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
197 | mnt_drop_write(ofs->upper_mnt); | |
198 | } | |
199 | ||
200 | struct dentry *ovl_workdir(struct dentry *dentry) | |
201 | { | |
202 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
203 | return ofs->workdir; | |
204 | } | |
205 | ||
206 | bool ovl_dentry_is_opaque(struct dentry *dentry) | |
207 | { | |
208 | struct ovl_entry *oe = dentry->d_fsdata; | |
209 | return oe->opaque; | |
210 | } | |
211 | ||
212 | void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) | |
213 | { | |
214 | struct ovl_entry *oe = dentry->d_fsdata; | |
215 | oe->opaque = opaque; | |
216 | } | |
217 | ||
218 | void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) | |
219 | { | |
220 | struct ovl_entry *oe = dentry->d_fsdata; | |
221 | ||
5955102c | 222 | WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode)); |
e9be9d5e | 223 | WARN_ON(oe->__upperdentry); |
e9be9d5e MS |
224 | /* |
225 | * Make sure upperdentry is consistent before making it visible to | |
226 | * ovl_upperdentry_dereference(). | |
227 | */ | |
228 | smp_wmb(); | |
229 | oe->__upperdentry = upperdentry; | |
230 | } | |
231 | ||
39b681f8 MS |
232 | void ovl_inode_update(struct inode *inode, struct inode *upperinode) |
233 | { | |
234 | WARN_ON(!upperinode); | |
51f7e52d | 235 | WARN_ON(!inode_unhashed(inode)); |
39b681f8 MS |
236 | WRITE_ONCE(inode->i_private, |
237 | (unsigned long) upperinode | OVL_ISUPPER_MASK); | |
51f7e52d MS |
238 | if (!S_ISDIR(upperinode->i_mode)) |
239 | __insert_inode_hash(inode, (unsigned long) upperinode); | |
39b681f8 MS |
240 | } |
241 | ||
e9be9d5e MS |
242 | void ovl_dentry_version_inc(struct dentry *dentry) |
243 | { | |
244 | struct ovl_entry *oe = dentry->d_fsdata; | |
245 | ||
5955102c | 246 | WARN_ON(!inode_is_locked(dentry->d_inode)); |
e9be9d5e MS |
247 | oe->version++; |
248 | } | |
249 | ||
250 | u64 ovl_dentry_version_get(struct dentry *dentry) | |
251 | { | |
252 | struct ovl_entry *oe = dentry->d_fsdata; | |
253 | ||
5955102c | 254 | WARN_ON(!inode_is_locked(dentry->d_inode)); |
e9be9d5e MS |
255 | return oe->version; |
256 | } | |
257 | ||
258 | bool ovl_is_whiteout(struct dentry *dentry) | |
259 | { | |
260 | struct inode *inode = dentry->d_inode; | |
261 | ||
262 | return inode && IS_WHITEOUT(inode); | |
263 | } | |
264 | ||
3fe6e52f AM |
265 | const struct cred *ovl_override_creds(struct super_block *sb) |
266 | { | |
267 | struct ovl_fs *ofs = sb->s_fs_info; | |
268 | ||
269 | return override_creds(ofs->creator_cred); | |
270 | } | |
271 | ||
e9be9d5e MS |
272 | static bool ovl_is_opaquedir(struct dentry *dentry) |
273 | { | |
274 | int res; | |
275 | char val; | |
276 | struct inode *inode = dentry->d_inode; | |
277 | ||
278 | if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr) | |
279 | return false; | |
280 | ||
ce23e640 | 281 | res = inode->i_op->getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1); |
e9be9d5e MS |
282 | if (res == 1 && val == 'y') |
283 | return true; | |
284 | ||
285 | return false; | |
286 | } | |
287 | ||
288 | static void ovl_dentry_release(struct dentry *dentry) | |
289 | { | |
290 | struct ovl_entry *oe = dentry->d_fsdata; | |
291 | ||
292 | if (oe) { | |
dd662667 MS |
293 | unsigned int i; |
294 | ||
e9be9d5e | 295 | dput(oe->__upperdentry); |
dd662667 MS |
296 | for (i = 0; i < oe->numlower; i++) |
297 | dput(oe->lowerstack[i].dentry); | |
e9be9d5e MS |
298 | kfree_rcu(oe, rcu); |
299 | } | |
300 | } | |
301 | ||
2d902671 MS |
302 | static struct dentry *ovl_d_real(struct dentry *dentry, |
303 | const struct inode *inode, | |
304 | unsigned int open_flags) | |
d101a125 MS |
305 | { |
306 | struct dentry *real; | |
307 | ||
308 | if (d_is_dir(dentry)) { | |
309 | if (!inode || inode == d_inode(dentry)) | |
310 | return dentry; | |
311 | goto bug; | |
312 | } | |
313 | ||
2d902671 MS |
314 | if (d_is_negative(dentry)) |
315 | return dentry; | |
316 | ||
317 | if (open_flags) { | |
318 | int err = ovl_open_maybe_copy_up(dentry, open_flags); | |
319 | ||
320 | if (err) | |
321 | return ERR_PTR(err); | |
322 | } | |
323 | ||
d101a125 MS |
324 | real = ovl_dentry_upper(dentry); |
325 | if (real && (!inode || inode == d_inode(real))) | |
326 | return real; | |
327 | ||
328 | real = ovl_dentry_lower(dentry); | |
329 | if (!real) | |
330 | goto bug; | |
331 | ||
332 | if (!inode || inode == d_inode(real)) | |
333 | return real; | |
334 | ||
335 | /* Handle recursion */ | |
2d902671 | 336 | return d_real(real, inode, open_flags); |
d101a125 | 337 | bug: |
656189d2 | 338 | WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, |
d101a125 MS |
339 | inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); |
340 | return dentry; | |
341 | } | |
342 | ||
7c03b5d4 MS |
343 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
344 | { | |
345 | struct ovl_entry *oe = dentry->d_fsdata; | |
346 | unsigned int i; | |
347 | int ret = 1; | |
348 | ||
349 | for (i = 0; i < oe->numlower; i++) { | |
350 | struct dentry *d = oe->lowerstack[i].dentry; | |
351 | ||
352 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
353 | ret = d->d_op->d_revalidate(d, flags); | |
354 | if (ret < 0) | |
355 | return ret; | |
356 | if (!ret) { | |
357 | if (!(flags & LOOKUP_RCU)) | |
358 | d_invalidate(d); | |
359 | return -ESTALE; | |
360 | } | |
361 | } | |
362 | } | |
363 | return 1; | |
364 | } | |
365 | ||
366 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
367 | { | |
368 | struct ovl_entry *oe = dentry->d_fsdata; | |
369 | unsigned int i; | |
370 | int ret = 1; | |
371 | ||
372 | for (i = 0; i < oe->numlower; i++) { | |
373 | struct dentry *d = oe->lowerstack[i].dentry; | |
374 | ||
375 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
376 | ret = d->d_op->d_weak_revalidate(d, flags); | |
377 | if (ret <= 0) | |
378 | break; | |
379 | } | |
380 | } | |
381 | return ret; | |
382 | } | |
383 | ||
e9be9d5e MS |
384 | static const struct dentry_operations ovl_dentry_operations = { |
385 | .d_release = ovl_dentry_release, | |
d101a125 | 386 | .d_real = ovl_d_real, |
e9be9d5e MS |
387 | }; |
388 | ||
7c03b5d4 MS |
389 | static const struct dentry_operations ovl_reval_dentry_operations = { |
390 | .d_release = ovl_dentry_release, | |
d101a125 | 391 | .d_real = ovl_d_real, |
7c03b5d4 MS |
392 | .d_revalidate = ovl_dentry_revalidate, |
393 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
394 | }; | |
395 | ||
dd662667 | 396 | static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) |
e9be9d5e | 397 | { |
dd662667 MS |
398 | size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); |
399 | struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); | |
400 | ||
401 | if (oe) | |
402 | oe->numlower = numlower; | |
403 | ||
404 | return oe; | |
e9be9d5e MS |
405 | } |
406 | ||
7c03b5d4 MS |
407 | static bool ovl_dentry_remote(struct dentry *dentry) |
408 | { | |
409 | return dentry->d_flags & | |
76bc8e28 MS |
410 | (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | |
411 | DCACHE_OP_REAL); | |
7c03b5d4 MS |
412 | } |
413 | ||
414 | static bool ovl_dentry_weird(struct dentry *dentry) | |
415 | { | |
416 | return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | | |
417 | DCACHE_MANAGE_TRANSIT | | |
418 | DCACHE_OP_HASH | | |
419 | DCACHE_OP_COMPARE); | |
420 | } | |
421 | ||
c1b2cc1a MS |
422 | static inline struct dentry *ovl_lookup_real(struct super_block *ovl_sb, |
423 | struct dentry *dir, | |
29c42e80 | 424 | const struct qstr *name) |
e9be9d5e | 425 | { |
c1b2cc1a | 426 | const struct cred *old_cred; |
e9be9d5e MS |
427 | struct dentry *dentry; |
428 | ||
c1b2cc1a MS |
429 | old_cred = ovl_override_creds(ovl_sb); |
430 | dentry = lookup_one_len_unlocked(name->name, dir, name->len); | |
431 | revert_creds(old_cred); | |
e9be9d5e MS |
432 | |
433 | if (IS_ERR(dentry)) { | |
434 | if (PTR_ERR(dentry) == -ENOENT) | |
435 | dentry = NULL; | |
436 | } else if (!dentry->d_inode) { | |
437 | dput(dentry); | |
438 | dentry = NULL; | |
7c03b5d4 | 439 | } else if (ovl_dentry_weird(dentry)) { |
a6f15d9a | 440 | dput(dentry); |
7c03b5d4 | 441 | /* Don't support traversing automounts and other weirdness */ |
a6f15d9a | 442 | dentry = ERR_PTR(-EREMOTE); |
e9be9d5e MS |
443 | } |
444 | return dentry; | |
445 | } | |
446 | ||
5ef88da5 MS |
447 | /* |
448 | * Returns next layer in stack starting from top. | |
449 | * Returns -1 if this is the last layer. | |
450 | */ | |
451 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path) | |
452 | { | |
453 | struct ovl_entry *oe = dentry->d_fsdata; | |
454 | ||
455 | BUG_ON(idx < 0); | |
456 | if (idx == 0) { | |
457 | ovl_path_upper(dentry, path); | |
458 | if (path->dentry) | |
459 | return oe->numlower ? 1 : -1; | |
460 | idx++; | |
461 | } | |
462 | BUG_ON(idx > oe->numlower); | |
463 | *path = oe->lowerstack[idx - 1]; | |
464 | ||
465 | return (idx < oe->numlower) ? idx + 1 : -1; | |
466 | } | |
467 | ||
e9be9d5e MS |
468 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
469 | unsigned int flags) | |
470 | { | |
471 | struct ovl_entry *oe; | |
3d3c6b89 MS |
472 | struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
473 | struct path *stack = NULL; | |
474 | struct dentry *upperdir, *upperdentry = NULL; | |
475 | unsigned int ctr = 0; | |
e9be9d5e | 476 | struct inode *inode = NULL; |
3d3c6b89 MS |
477 | bool upperopaque = false; |
478 | struct dentry *this, *prev = NULL; | |
479 | unsigned int i; | |
e9be9d5e MS |
480 | int err; |
481 | ||
3d3c6b89 | 482 | upperdir = ovl_upperdentry_dereference(poe); |
e9be9d5e | 483 | if (upperdir) { |
c1b2cc1a | 484 | this = ovl_lookup_real(dentry->d_sb, upperdir, &dentry->d_name); |
3d3c6b89 MS |
485 | err = PTR_ERR(this); |
486 | if (IS_ERR(this)) | |
487 | goto out; | |
488 | ||
3e01cee3 | 489 | if (this) { |
7c03b5d4 MS |
490 | if (unlikely(ovl_dentry_remote(this))) { |
491 | dput(this); | |
492 | err = -EREMOTE; | |
493 | goto out; | |
494 | } | |
3d3c6b89 MS |
495 | if (ovl_is_whiteout(this)) { |
496 | dput(this); | |
497 | this = NULL; | |
498 | upperopaque = true; | |
3e01cee3 | 499 | } else if (poe->numlower && ovl_is_opaquedir(this)) { |
3d3c6b89 | 500 | upperopaque = true; |
e9be9d5e MS |
501 | } |
502 | } | |
3d3c6b89 | 503 | upperdentry = prev = this; |
e9be9d5e | 504 | } |
3d3c6b89 MS |
505 | |
506 | if (!upperopaque && poe->numlower) { | |
507 | err = -ENOMEM; | |
508 | stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); | |
509 | if (!stack) | |
510 | goto out_put_upper; | |
e9be9d5e MS |
511 | } |
512 | ||
3d3c6b89 MS |
513 | for (i = 0; !upperopaque && i < poe->numlower; i++) { |
514 | bool opaque = false; | |
515 | struct path lowerpath = poe->lowerstack[i]; | |
516 | ||
c1b2cc1a MS |
517 | this = ovl_lookup_real(dentry->d_sb, |
518 | lowerpath.dentry, &dentry->d_name); | |
3d3c6b89 | 519 | err = PTR_ERR(this); |
09e10322 MS |
520 | if (IS_ERR(this)) { |
521 | /* | |
522 | * If it's positive, then treat ENAMETOOLONG as ENOENT. | |
523 | */ | |
524 | if (err == -ENAMETOOLONG && (upperdentry || ctr)) | |
525 | continue; | |
3d3c6b89 | 526 | goto out_put; |
09e10322 | 527 | } |
3d3c6b89 MS |
528 | if (!this) |
529 | continue; | |
3e01cee3 MS |
530 | if (ovl_is_whiteout(this)) { |
531 | dput(this); | |
532 | break; | |
533 | } | |
3d3c6b89 | 534 | /* |
3e01cee3 MS |
535 | * Only makes sense to check opaque dir if this is not the |
536 | * lowermost layer. | |
3d3c6b89 | 537 | */ |
3e01cee3 MS |
538 | if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) |
539 | opaque = true; | |
a425c037 | 540 | |
541 | if (prev && (!S_ISDIR(prev->d_inode->i_mode) || | |
542 | !S_ISDIR(this->d_inode->i_mode))) { | |
543 | /* | |
544 | * FIXME: check for upper-opaqueness maybe better done | |
545 | * in remove code. | |
546 | */ | |
3d3c6b89 MS |
547 | if (prev == upperdentry) |
548 | upperopaque = true; | |
549 | dput(this); | |
550 | break; | |
551 | } | |
a425c037 | 552 | /* |
553 | * If this is a non-directory then stop here. | |
554 | */ | |
555 | if (!S_ISDIR(this->d_inode->i_mode)) | |
556 | opaque = true; | |
557 | ||
3d3c6b89 MS |
558 | stack[ctr].dentry = this; |
559 | stack[ctr].mnt = lowerpath.mnt; | |
560 | ctr++; | |
561 | prev = this; | |
562 | if (opaque) | |
563 | break; | |
e9be9d5e MS |
564 | } |
565 | ||
3d3c6b89 MS |
566 | oe = ovl_alloc_entry(ctr); |
567 | err = -ENOMEM; | |
568 | if (!oe) | |
569 | goto out_put; | |
570 | ||
571 | if (upperdentry || ctr) { | |
e9be9d5e | 572 | struct dentry *realdentry; |
39b681f8 | 573 | struct inode *realinode; |
e9be9d5e | 574 | |
3d3c6b89 | 575 | realdentry = upperdentry ? upperdentry : stack[0].dentry; |
39b681f8 | 576 | realinode = d_inode(realdentry); |
3d3c6b89 | 577 | |
e9be9d5e | 578 | err = -ENOMEM; |
51f7e52d MS |
579 | if (upperdentry && !d_is_dir(upperdentry)) { |
580 | inode = ovl_get_inode(dentry->d_sb, realinode); | |
581 | } else { | |
582 | inode = ovl_new_inode(dentry->d_sb, realinode->i_mode); | |
583 | if (inode) | |
584 | ovl_inode_init(inode, realinode, !!upperdentry); | |
585 | } | |
e9be9d5e | 586 | if (!inode) |
3d3c6b89 | 587 | goto out_free_oe; |
e9be9d5e MS |
588 | ovl_copyattr(realdentry->d_inode, inode); |
589 | } | |
590 | ||
3d3c6b89 | 591 | oe->opaque = upperopaque; |
e9be9d5e | 592 | oe->__upperdentry = upperdentry; |
3d3c6b89 MS |
593 | memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); |
594 | kfree(stack); | |
e9be9d5e MS |
595 | dentry->d_fsdata = oe; |
596 | d_add(dentry, inode); | |
597 | ||
598 | return NULL; | |
599 | ||
3d3c6b89 | 600 | out_free_oe: |
e9be9d5e | 601 | kfree(oe); |
3d3c6b89 MS |
602 | out_put: |
603 | for (i = 0; i < ctr; i++) | |
604 | dput(stack[i].dentry); | |
605 | kfree(stack); | |
606 | out_put_upper: | |
607 | dput(upperdentry); | |
e9be9d5e MS |
608 | out: |
609 | return ERR_PTR(err); | |
610 | } | |
611 | ||
612 | struct file *ovl_path_open(struct path *path, int flags) | |
613 | { | |
d719e8f2 | 614 | return dentry_open(path, flags | O_NOATIME, current_cred()); |
e9be9d5e MS |
615 | } |
616 | ||
617 | static void ovl_put_super(struct super_block *sb) | |
618 | { | |
619 | struct ovl_fs *ufs = sb->s_fs_info; | |
dd662667 | 620 | unsigned i; |
e9be9d5e MS |
621 | |
622 | dput(ufs->workdir); | |
623 | mntput(ufs->upper_mnt); | |
dd662667 MS |
624 | for (i = 0; i < ufs->numlower; i++) |
625 | mntput(ufs->lower_mnt[i]); | |
5ffdbe8b | 626 | kfree(ufs->lower_mnt); |
e9be9d5e | 627 | |
f45827e8 EZ |
628 | kfree(ufs->config.lowerdir); |
629 | kfree(ufs->config.upperdir); | |
630 | kfree(ufs->config.workdir); | |
3fe6e52f | 631 | put_cred(ufs->creator_cred); |
e9be9d5e MS |
632 | kfree(ufs); |
633 | } | |
634 | ||
cc259639 AW |
635 | /** |
636 | * ovl_statfs | |
637 | * @sb: The overlayfs super block | |
638 | * @buf: The struct kstatfs to fill in with stats | |
639 | * | |
640 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 641 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
642 | */ |
643 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
644 | { | |
645 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
646 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
647 | struct path path; | |
648 | int err; | |
649 | ||
4ebc5818 | 650 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
651 | |
652 | err = vfs_statfs(&path, buf); | |
653 | if (!err) { | |
654 | buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); | |
655 | buf->f_type = OVERLAYFS_SUPER_MAGIC; | |
656 | } | |
657 | ||
658 | return err; | |
659 | } | |
660 | ||
f45827e8 EZ |
661 | /** |
662 | * ovl_show_options | |
663 | * | |
664 | * Prints the mount options for a given superblock. | |
665 | * Returns zero; does not fail. | |
666 | */ | |
667 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
668 | { | |
669 | struct super_block *sb = dentry->d_sb; | |
670 | struct ovl_fs *ufs = sb->s_fs_info; | |
671 | ||
a068acf2 | 672 | seq_show_option(m, "lowerdir", ufs->config.lowerdir); |
53a08cb9 | 673 | if (ufs->config.upperdir) { |
a068acf2 KC |
674 | seq_show_option(m, "upperdir", ufs->config.upperdir); |
675 | seq_show_option(m, "workdir", ufs->config.workdir); | |
53a08cb9 | 676 | } |
8d3095f4 MS |
677 | if (ufs->config.default_permissions) |
678 | seq_puts(m, ",default_permissions"); | |
f45827e8 EZ |
679 | return 0; |
680 | } | |
681 | ||
3cdf6fe9 SL |
682 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
683 | { | |
684 | struct ovl_fs *ufs = sb->s_fs_info; | |
685 | ||
cc6f67bc | 686 | if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) |
3cdf6fe9 SL |
687 | return -EROFS; |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
e9be9d5e MS |
692 | static const struct super_operations ovl_super_operations = { |
693 | .put_super = ovl_put_super, | |
cc259639 | 694 | .statfs = ovl_statfs, |
f45827e8 | 695 | .show_options = ovl_show_options, |
3cdf6fe9 | 696 | .remount_fs = ovl_remount, |
eead4f2d | 697 | .drop_inode = generic_delete_inode, |
e9be9d5e MS |
698 | }; |
699 | ||
700 | enum { | |
701 | OPT_LOWERDIR, | |
702 | OPT_UPPERDIR, | |
703 | OPT_WORKDIR, | |
8d3095f4 | 704 | OPT_DEFAULT_PERMISSIONS, |
e9be9d5e MS |
705 | OPT_ERR, |
706 | }; | |
707 | ||
708 | static const match_table_t ovl_tokens = { | |
709 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
710 | {OPT_UPPERDIR, "upperdir=%s"}, | |
711 | {OPT_WORKDIR, "workdir=%s"}, | |
8d3095f4 | 712 | {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
e9be9d5e MS |
713 | {OPT_ERR, NULL} |
714 | }; | |
715 | ||
91c77947 MS |
716 | static char *ovl_next_opt(char **s) |
717 | { | |
718 | char *sbegin = *s; | |
719 | char *p; | |
720 | ||
721 | if (sbegin == NULL) | |
722 | return NULL; | |
723 | ||
724 | for (p = sbegin; *p; p++) { | |
725 | if (*p == '\\') { | |
726 | p++; | |
727 | if (!*p) | |
728 | break; | |
729 | } else if (*p == ',') { | |
730 | *p = '\0'; | |
731 | *s = p + 1; | |
732 | return sbegin; | |
733 | } | |
734 | } | |
735 | *s = NULL; | |
736 | return sbegin; | |
737 | } | |
738 | ||
e9be9d5e MS |
739 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
740 | { | |
741 | char *p; | |
742 | ||
91c77947 | 743 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
744 | int token; |
745 | substring_t args[MAX_OPT_ARGS]; | |
746 | ||
747 | if (!*p) | |
748 | continue; | |
749 | ||
750 | token = match_token(p, ovl_tokens, args); | |
751 | switch (token) { | |
752 | case OPT_UPPERDIR: | |
753 | kfree(config->upperdir); | |
754 | config->upperdir = match_strdup(&args[0]); | |
755 | if (!config->upperdir) | |
756 | return -ENOMEM; | |
757 | break; | |
758 | ||
759 | case OPT_LOWERDIR: | |
760 | kfree(config->lowerdir); | |
761 | config->lowerdir = match_strdup(&args[0]); | |
762 | if (!config->lowerdir) | |
763 | return -ENOMEM; | |
764 | break; | |
765 | ||
766 | case OPT_WORKDIR: | |
767 | kfree(config->workdir); | |
768 | config->workdir = match_strdup(&args[0]); | |
769 | if (!config->workdir) | |
770 | return -ENOMEM; | |
771 | break; | |
772 | ||
8d3095f4 MS |
773 | case OPT_DEFAULT_PERMISSIONS: |
774 | config->default_permissions = true; | |
775 | break; | |
776 | ||
e9be9d5e | 777 | default: |
bead55ef | 778 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
779 | return -EINVAL; |
780 | } | |
781 | } | |
71cbad7e | 782 | |
783 | /* Workdir is useless in non-upper mount */ | |
784 | if (!config->upperdir && config->workdir) { | |
785 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
786 | config->workdir); | |
787 | kfree(config->workdir); | |
788 | config->workdir = NULL; | |
789 | } | |
790 | ||
e9be9d5e MS |
791 | return 0; |
792 | } | |
793 | ||
794 | #define OVL_WORKDIR_NAME "work" | |
795 | ||
796 | static struct dentry *ovl_workdir_create(struct vfsmount *mnt, | |
797 | struct dentry *dentry) | |
798 | { | |
799 | struct inode *dir = dentry->d_inode; | |
800 | struct dentry *work; | |
801 | int err; | |
802 | bool retried = false; | |
803 | ||
804 | err = mnt_want_write(mnt); | |
805 | if (err) | |
806 | return ERR_PTR(err); | |
807 | ||
5955102c | 808 | inode_lock_nested(dir, I_MUTEX_PARENT); |
e9be9d5e MS |
809 | retry: |
810 | work = lookup_one_len(OVL_WORKDIR_NAME, dentry, | |
811 | strlen(OVL_WORKDIR_NAME)); | |
812 | ||
813 | if (!IS_ERR(work)) { | |
814 | struct kstat stat = { | |
815 | .mode = S_IFDIR | 0, | |
816 | }; | |
817 | ||
818 | if (work->d_inode) { | |
819 | err = -EEXIST; | |
820 | if (retried) | |
821 | goto out_dput; | |
822 | ||
823 | retried = true; | |
824 | ovl_cleanup(dir, work); | |
825 | dput(work); | |
826 | goto retry; | |
827 | } | |
828 | ||
829 | err = ovl_create_real(dir, work, &stat, NULL, NULL, true); | |
830 | if (err) | |
831 | goto out_dput; | |
832 | } | |
833 | out_unlock: | |
5955102c | 834 | inode_unlock(dir); |
e9be9d5e MS |
835 | mnt_drop_write(mnt); |
836 | ||
837 | return work; | |
838 | ||
839 | out_dput: | |
840 | dput(work); | |
841 | work = ERR_PTR(err); | |
842 | goto out_unlock; | |
843 | } | |
844 | ||
91c77947 MS |
845 | static void ovl_unescape(char *s) |
846 | { | |
847 | char *d = s; | |
848 | ||
849 | for (;; s++, d++) { | |
850 | if (*s == '\\') | |
851 | s++; | |
852 | *d = *s; | |
853 | if (!*s) | |
854 | break; | |
855 | } | |
856 | } | |
857 | ||
ab508822 MS |
858 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
859 | { | |
a78d9f0d | 860 | int err = -EINVAL; |
ab508822 | 861 | |
a78d9f0d MS |
862 | if (!*name) { |
863 | pr_err("overlayfs: empty lowerdir\n"); | |
864 | goto out; | |
865 | } | |
ab508822 MS |
866 | err = kern_path(name, LOOKUP_FOLLOW, path); |
867 | if (err) { | |
868 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
869 | goto out; | |
870 | } | |
871 | err = -EINVAL; | |
7c03b5d4 | 872 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
873 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
874 | goto out_put; | |
875 | } | |
876 | if (!S_ISDIR(path->dentry->d_inode->i_mode)) { | |
877 | pr_err("overlayfs: '%s' not a directory\n", name); | |
878 | goto out_put; | |
879 | } | |
880 | return 0; | |
881 | ||
882 | out_put: | |
883 | path_put(path); | |
884 | out: | |
885 | return err; | |
886 | } | |
887 | ||
888 | static int ovl_mount_dir(const char *name, struct path *path) | |
889 | { | |
890 | int err = -ENOMEM; | |
891 | char *tmp = kstrdup(name, GFP_KERNEL); | |
892 | ||
893 | if (tmp) { | |
894 | ovl_unescape(tmp); | |
895 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
896 | |
897 | if (!err) | |
898 | if (ovl_dentry_remote(path->dentry)) { | |
899 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
900 | tmp); | |
901 | path_put(path); | |
902 | err = -EINVAL; | |
903 | } | |
ab508822 MS |
904 | kfree(tmp); |
905 | } | |
906 | return err; | |
907 | } | |
908 | ||
909 | static int ovl_lower_dir(const char *name, struct path *path, long *namelen, | |
7c03b5d4 | 910 | int *stack_depth, bool *remote) |
ab508822 MS |
911 | { |
912 | int err; | |
913 | struct kstatfs statfs; | |
914 | ||
a78d9f0d | 915 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
916 | if (err) |
917 | goto out; | |
918 | ||
919 | err = vfs_statfs(path, &statfs); | |
920 | if (err) { | |
921 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
922 | goto out_put; | |
923 | } | |
924 | *namelen = max(*namelen, statfs.f_namelen); | |
925 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); | |
926 | ||
7c03b5d4 MS |
927 | if (ovl_dentry_remote(path->dentry)) |
928 | *remote = true; | |
929 | ||
ab508822 MS |
930 | return 0; |
931 | ||
932 | out_put: | |
933 | path_put(path); | |
934 | out: | |
935 | return err; | |
936 | } | |
937 | ||
e9be9d5e MS |
938 | /* Workdir should not be subdir of upperdir and vice versa */ |
939 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
940 | { | |
941 | bool ok = false; | |
942 | ||
943 | if (workdir != upperdir) { | |
944 | ok = (lock_rename(workdir, upperdir) == NULL); | |
945 | unlock_rename(workdir, upperdir); | |
946 | } | |
947 | return ok; | |
948 | } | |
949 | ||
a78d9f0d MS |
950 | static unsigned int ovl_split_lowerdirs(char *str) |
951 | { | |
952 | unsigned int ctr = 1; | |
953 | char *s, *d; | |
954 | ||
955 | for (s = d = str;; s++, d++) { | |
956 | if (*s == '\\') { | |
957 | s++; | |
958 | } else if (*s == ':') { | |
959 | *d = '\0'; | |
960 | ctr++; | |
961 | continue; | |
962 | } | |
963 | *d = *s; | |
964 | if (!*s) | |
965 | break; | |
966 | } | |
967 | return ctr; | |
968 | } | |
969 | ||
d837a49b MS |
970 | static int ovl_posix_acl_xattr_set(const struct xattr_handler *handler, |
971 | struct dentry *dentry, struct inode *inode, | |
972 | const char *name, const void *value, | |
973 | size_t size, int flags) | |
974 | { | |
975 | struct dentry *workdir = ovl_workdir(dentry); | |
976 | struct inode *realinode = ovl_inode_real(inode, NULL); | |
977 | struct posix_acl *acl = NULL; | |
978 | int err; | |
979 | ||
980 | /* Check that everything is OK before copy-up */ | |
981 | if (value) { | |
982 | acl = posix_acl_from_xattr(&init_user_ns, value, size); | |
983 | if (IS_ERR(acl)) | |
984 | return PTR_ERR(acl); | |
985 | } | |
986 | err = -EOPNOTSUPP; | |
987 | if (!IS_POSIXACL(d_inode(workdir))) | |
988 | goto out_acl_release; | |
989 | if (!realinode->i_op->set_acl) | |
990 | goto out_acl_release; | |
991 | if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { | |
992 | err = acl ? -EACCES : 0; | |
993 | goto out_acl_release; | |
994 | } | |
995 | err = -EPERM; | |
996 | if (!inode_owner_or_capable(inode)) | |
997 | goto out_acl_release; | |
998 | ||
999 | posix_acl_release(acl); | |
1000 | ||
1001 | return ovl_setxattr(dentry, inode, handler->name, value, size, flags); | |
1002 | ||
1003 | out_acl_release: | |
1004 | posix_acl_release(acl); | |
1005 | return err; | |
1006 | } | |
1007 | ||
1008 | static int ovl_other_xattr_set(const struct xattr_handler *handler, | |
1009 | struct dentry *dentry, struct inode *inode, | |
1010 | const char *name, const void *value, | |
1011 | size_t size, int flags) | |
1012 | { | |
1013 | return ovl_setxattr(dentry, inode, name, value, size, flags); | |
1014 | } | |
1015 | ||
1016 | static int ovl_own_xattr_set(const struct xattr_handler *handler, | |
1017 | struct dentry *dentry, struct inode *inode, | |
1018 | const char *name, const void *value, | |
1019 | size_t size, int flags) | |
1020 | { | |
1021 | return -EPERM; | |
1022 | } | |
1023 | ||
1024 | static const struct xattr_handler ovl_posix_acl_access_xattr_handler = { | |
1025 | .name = XATTR_NAME_POSIX_ACL_ACCESS, | |
1026 | .flags = ACL_TYPE_ACCESS, | |
1027 | .set = ovl_posix_acl_xattr_set, | |
1028 | }; | |
1029 | ||
1030 | static const struct xattr_handler ovl_posix_acl_default_xattr_handler = { | |
1031 | .name = XATTR_NAME_POSIX_ACL_DEFAULT, | |
1032 | .flags = ACL_TYPE_DEFAULT, | |
1033 | .set = ovl_posix_acl_xattr_set, | |
1034 | }; | |
1035 | ||
1036 | static const struct xattr_handler ovl_own_xattr_handler = { | |
1037 | .prefix = OVL_XATTR_PREFIX, | |
1038 | .set = ovl_own_xattr_set, | |
1039 | }; | |
1040 | ||
1041 | static const struct xattr_handler ovl_other_xattr_handler = { | |
1042 | .prefix = "", /* catch all */ | |
1043 | .set = ovl_other_xattr_set, | |
1044 | }; | |
1045 | ||
1046 | static const struct xattr_handler *ovl_xattr_handlers[] = { | |
1047 | &ovl_posix_acl_access_xattr_handler, | |
1048 | &ovl_posix_acl_default_xattr_handler, | |
1049 | &ovl_own_xattr_handler, | |
1050 | &ovl_other_xattr_handler, | |
1051 | NULL | |
1052 | }; | |
1053 | ||
1054 | static const struct xattr_handler *ovl_xattr_noacl_handlers[] = { | |
1055 | &ovl_own_xattr_handler, | |
1056 | &ovl_other_xattr_handler, | |
1057 | NULL, | |
1058 | }; | |
1059 | ||
e9be9d5e MS |
1060 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
1061 | { | |
53a08cb9 MS |
1062 | struct path upperpath = { NULL, NULL }; |
1063 | struct path workpath = { NULL, NULL }; | |
e9be9d5e | 1064 | struct dentry *root_dentry; |
39b681f8 | 1065 | struct inode *realinode; |
e9be9d5e MS |
1066 | struct ovl_entry *oe; |
1067 | struct ovl_fs *ufs; | |
a78d9f0d MS |
1068 | struct path *stack = NULL; |
1069 | char *lowertmp; | |
1070 | char *lower; | |
1071 | unsigned int numlower; | |
1072 | unsigned int stacklen = 0; | |
dd662667 | 1073 | unsigned int i; |
7c03b5d4 | 1074 | bool remote = false; |
e9be9d5e MS |
1075 | int err; |
1076 | ||
f45827e8 EZ |
1077 | err = -ENOMEM; |
1078 | ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
1079 | if (!ufs) | |
e9be9d5e MS |
1080 | goto out; |
1081 | ||
f45827e8 EZ |
1082 | err = ovl_parse_opt((char *) data, &ufs->config); |
1083 | if (err) | |
1084 | goto out_free_config; | |
1085 | ||
e9be9d5e | 1086 | err = -EINVAL; |
53a08cb9 | 1087 | if (!ufs->config.lowerdir) { |
07f2af7b KK |
1088 | if (!silent) |
1089 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
e9be9d5e MS |
1090 | goto out_free_config; |
1091 | } | |
1092 | ||
53a08cb9 | 1093 | sb->s_stack_depth = 0; |
cf9a6784 | 1094 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
53a08cb9 | 1095 | if (ufs->config.upperdir) { |
53a08cb9 MS |
1096 | if (!ufs->config.workdir) { |
1097 | pr_err("overlayfs: missing 'workdir'\n"); | |
1098 | goto out_free_config; | |
1099 | } | |
e9be9d5e | 1100 | |
53a08cb9 MS |
1101 | err = ovl_mount_dir(ufs->config.upperdir, &upperpath); |
1102 | if (err) | |
1103 | goto out_free_config; | |
e9be9d5e | 1104 | |
71cbad7e | 1105 | /* Upper fs should not be r/o */ |
1106 | if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { | |
1107 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
1108 | err = -EINVAL; | |
1109 | goto out_put_upperpath; | |
1110 | } | |
1111 | ||
53a08cb9 MS |
1112 | err = ovl_mount_dir(ufs->config.workdir, &workpath); |
1113 | if (err) | |
1114 | goto out_put_upperpath; | |
1115 | ||
2f83fd8c | 1116 | err = -EINVAL; |
53a08cb9 MS |
1117 | if (upperpath.mnt != workpath.mnt) { |
1118 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); | |
1119 | goto out_put_workpath; | |
1120 | } | |
1121 | if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) { | |
1122 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); | |
1123 | goto out_put_workpath; | |
1124 | } | |
1125 | sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth; | |
cc259639 | 1126 | } |
a78d9f0d MS |
1127 | err = -ENOMEM; |
1128 | lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL); | |
1129 | if (!lowertmp) | |
ab508822 | 1130 | goto out_put_workpath; |
69c433ed | 1131 | |
a78d9f0d MS |
1132 | err = -EINVAL; |
1133 | stacklen = ovl_split_lowerdirs(lowertmp); | |
6be4506e | 1134 | if (stacklen > OVL_MAX_STACK) { |
1135 | pr_err("overlayfs: too many lower directries, limit is %d\n", | |
1136 | OVL_MAX_STACK); | |
a78d9f0d | 1137 | goto out_free_lowertmp; |
6be4506e | 1138 | } else if (!ufs->config.upperdir && stacklen == 1) { |
1139 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); | |
1140 | goto out_free_lowertmp; | |
1141 | } | |
a78d9f0d MS |
1142 | |
1143 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); | |
1144 | if (!stack) | |
1145 | goto out_free_lowertmp; | |
1146 | ||
1147 | lower = lowertmp; | |
1148 | for (numlower = 0; numlower < stacklen; numlower++) { | |
1149 | err = ovl_lower_dir(lower, &stack[numlower], | |
7c03b5d4 MS |
1150 | &ufs->lower_namelen, &sb->s_stack_depth, |
1151 | &remote); | |
a78d9f0d MS |
1152 | if (err) |
1153 | goto out_put_lowerpath; | |
1154 | ||
1155 | lower = strchr(lower, '\0') + 1; | |
1156 | } | |
1157 | ||
69c433ed | 1158 | err = -EINVAL; |
ab508822 | 1159 | sb->s_stack_depth++; |
69c433ed MS |
1160 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
1161 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
3b7a9a24 | 1162 | goto out_put_lowerpath; |
69c433ed MS |
1163 | } |
1164 | ||
53a08cb9 MS |
1165 | if (ufs->config.upperdir) { |
1166 | ufs->upper_mnt = clone_private_mount(&upperpath); | |
1167 | err = PTR_ERR(ufs->upper_mnt); | |
1168 | if (IS_ERR(ufs->upper_mnt)) { | |
1169 | pr_err("overlayfs: failed to clone upperpath\n"); | |
1170 | goto out_put_lowerpath; | |
1171 | } | |
d719e8f2 MS |
1172 | /* Don't inherit atime flags */ |
1173 | ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); | |
1174 | ||
1175 | sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran; | |
3b7a9a24 | 1176 | |
53a08cb9 MS |
1177 | ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); |
1178 | err = PTR_ERR(ufs->workdir); | |
1179 | if (IS_ERR(ufs->workdir)) { | |
cc6f67bc MS |
1180 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
1181 | ufs->config.workdir, OVL_WORKDIR_NAME, -err); | |
1182 | sb->s_flags |= MS_RDONLY; | |
1183 | ufs->workdir = NULL; | |
53a08cb9 | 1184 | } |
45aebeaf VG |
1185 | |
1186 | /* | |
1187 | * Upper should support d_type, else whiteouts are visible. | |
1188 | * Given workdir and upper are on same fs, we can do | |
21765194 VG |
1189 | * iterate_dir() on workdir. This check requires successful |
1190 | * creation of workdir in previous step. | |
45aebeaf | 1191 | */ |
21765194 VG |
1192 | if (ufs->workdir) { |
1193 | err = ovl_check_d_type_supported(&workpath); | |
1194 | if (err < 0) | |
1195 | goto out_put_workdir; | |
45aebeaf | 1196 | |
e7c0b599 VG |
1197 | /* |
1198 | * We allowed this configuration and don't want to | |
1199 | * break users over kernel upgrade. So warn instead | |
1200 | * of erroring out. | |
1201 | */ | |
1202 | if (!err) | |
1203 | pr_warn("overlayfs: upper fs needs to support d_type.\n"); | |
45aebeaf | 1204 | } |
e9be9d5e MS |
1205 | } |
1206 | ||
2f83fd8c | 1207 | err = -ENOMEM; |
a78d9f0d | 1208 | ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); |
dd662667 | 1209 | if (ufs->lower_mnt == NULL) |
3b7a9a24 | 1210 | goto out_put_workdir; |
a78d9f0d MS |
1211 | for (i = 0; i < numlower; i++) { |
1212 | struct vfsmount *mnt = clone_private_mount(&stack[i]); | |
dd662667 | 1213 | |
2f83fd8c | 1214 | err = PTR_ERR(mnt); |
a78d9f0d MS |
1215 | if (IS_ERR(mnt)) { |
1216 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
1217 | goto out_put_lower_mnt; | |
1218 | } | |
1219 | /* | |
1220 | * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
1221 | * will fail instead of modifying lower fs. | |
1222 | */ | |
d719e8f2 | 1223 | mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; |
dd662667 | 1224 | |
a78d9f0d MS |
1225 | ufs->lower_mnt[ufs->numlower] = mnt; |
1226 | ufs->numlower++; | |
1227 | } | |
e9be9d5e | 1228 | |
71cbad7e | 1229 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
1230 | if (!ufs->upper_mnt) | |
e9be9d5e MS |
1231 | sb->s_flags |= MS_RDONLY; |
1232 | ||
7c03b5d4 MS |
1233 | if (remote) |
1234 | sb->s_d_op = &ovl_reval_dentry_operations; | |
1235 | else | |
1236 | sb->s_d_op = &ovl_dentry_operations; | |
e9be9d5e | 1237 | |
3fe6e52f AM |
1238 | ufs->creator_cred = prepare_creds(); |
1239 | if (!ufs->creator_cred) | |
1240 | goto out_put_lower_mnt; | |
1241 | ||
e9be9d5e | 1242 | err = -ENOMEM; |
a78d9f0d | 1243 | oe = ovl_alloc_entry(numlower); |
3b7a9a24 | 1244 | if (!oe) |
3fe6e52f | 1245 | goto out_put_cred; |
e9be9d5e | 1246 | |
39b681f8 | 1247 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR)); |
e9be9d5e | 1248 | if (!root_dentry) |
3b7a9a24 | 1249 | goto out_free_oe; |
e9be9d5e MS |
1250 | |
1251 | mntput(upperpath.mnt); | |
a78d9f0d MS |
1252 | for (i = 0; i < numlower; i++) |
1253 | mntput(stack[i].mnt); | |
e9be9d5e | 1254 | path_put(&workpath); |
a78d9f0d | 1255 | kfree(lowertmp); |
e9be9d5e MS |
1256 | |
1257 | oe->__upperdentry = upperpath.dentry; | |
a78d9f0d MS |
1258 | for (i = 0; i < numlower; i++) { |
1259 | oe->lowerstack[i].dentry = stack[i].dentry; | |
1260 | oe->lowerstack[i].mnt = ufs->lower_mnt[i]; | |
1261 | } | |
0f95502a | 1262 | kfree(stack); |
e9be9d5e MS |
1263 | |
1264 | root_dentry->d_fsdata = oe; | |
1265 | ||
39b681f8 MS |
1266 | realinode = d_inode(ovl_dentry_real(root_dentry)); |
1267 | ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); | |
1268 | ovl_copyattr(realinode, d_inode(root_dentry)); | |
ed06e069 | 1269 | |
cc259639 | 1270 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
e9be9d5e | 1271 | sb->s_op = &ovl_super_operations; |
d837a49b MS |
1272 | if (IS_ENABLED(CONFIG_FS_POSIX_ACL)) |
1273 | sb->s_xattr = ovl_xattr_handlers; | |
1274 | else | |
1275 | sb->s_xattr = ovl_xattr_noacl_handlers; | |
e9be9d5e MS |
1276 | sb->s_root = root_dentry; |
1277 | sb->s_fs_info = ufs; | |
39a25b2b | 1278 | sb->s_flags |= MS_POSIXACL; |
e9be9d5e MS |
1279 | |
1280 | return 0; | |
1281 | ||
3b7a9a24 MS |
1282 | out_free_oe: |
1283 | kfree(oe); | |
3fe6e52f AM |
1284 | out_put_cred: |
1285 | put_cred(ufs->creator_cred); | |
e9be9d5e | 1286 | out_put_lower_mnt: |
dd662667 MS |
1287 | for (i = 0; i < ufs->numlower; i++) |
1288 | mntput(ufs->lower_mnt[i]); | |
1289 | kfree(ufs->lower_mnt); | |
3b7a9a24 MS |
1290 | out_put_workdir: |
1291 | dput(ufs->workdir); | |
e9be9d5e | 1292 | mntput(ufs->upper_mnt); |
e9be9d5e | 1293 | out_put_lowerpath: |
a78d9f0d MS |
1294 | for (i = 0; i < numlower; i++) |
1295 | path_put(&stack[i]); | |
1296 | kfree(stack); | |
1297 | out_free_lowertmp: | |
1298 | kfree(lowertmp); | |
3b7a9a24 MS |
1299 | out_put_workpath: |
1300 | path_put(&workpath); | |
e9be9d5e MS |
1301 | out_put_upperpath: |
1302 | path_put(&upperpath); | |
e9be9d5e | 1303 | out_free_config: |
f45827e8 EZ |
1304 | kfree(ufs->config.lowerdir); |
1305 | kfree(ufs->config.upperdir); | |
1306 | kfree(ufs->config.workdir); | |
1307 | kfree(ufs); | |
e9be9d5e MS |
1308 | out: |
1309 | return err; | |
1310 | } | |
1311 | ||
1312 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
1313 | const char *dev_name, void *raw_data) | |
1314 | { | |
1315 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
1316 | } | |
1317 | ||
1318 | static struct file_system_type ovl_fs_type = { | |
1319 | .owner = THIS_MODULE, | |
ef94b186 | 1320 | .name = "overlay", |
e9be9d5e MS |
1321 | .mount = ovl_mount, |
1322 | .kill_sb = kill_anon_super, | |
1323 | }; | |
ef94b186 | 1324 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e MS |
1325 | |
1326 | static int __init ovl_init(void) | |
1327 | { | |
1328 | return register_filesystem(&ovl_fs_type); | |
1329 | } | |
1330 | ||
1331 | static void __exit ovl_exit(void) | |
1332 | { | |
1333 | unregister_filesystem(&ovl_fs_type); | |
1334 | } | |
1335 | ||
1336 | module_init(ovl_init); | |
1337 | module_exit(ovl_exit); |