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> | |
12 | #include <linux/xattr.h> | |
13 | #include <linux/security.h> | |
14 | #include <linux/mount.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/parser.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/sched.h> | |
cc259639 | 19 | #include <linux/statfs.h> |
f45827e8 | 20 | #include <linux/seq_file.h> |
e9be9d5e MS |
21 | #include "overlayfs.h" |
22 | ||
23 | MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
24 | MODULE_DESCRIPTION("Overlay filesystem"); | |
25 | MODULE_LICENSE("GPL"); | |
26 | ||
ef94b186 | 27 | #define OVERLAYFS_SUPER_MAGIC 0x794c7630 |
cc259639 | 28 | |
f45827e8 EZ |
29 | struct ovl_config { |
30 | char *lowerdir; | |
31 | char *upperdir; | |
32 | char *workdir; | |
33 | }; | |
34 | ||
e9be9d5e MS |
35 | /* private information held for overlayfs's superblock */ |
36 | struct ovl_fs { | |
37 | struct vfsmount *upper_mnt; | |
dd662667 MS |
38 | unsigned numlower; |
39 | struct vfsmount **lower_mnt; | |
e9be9d5e | 40 | struct dentry *workdir; |
cc259639 | 41 | long lower_namelen; |
f45827e8 EZ |
42 | /* pathnames of lower and upper dirs, for show_options */ |
43 | struct ovl_config config; | |
e9be9d5e MS |
44 | }; |
45 | ||
46 | struct ovl_dir_cache; | |
47 | ||
48 | /* private information held for every overlayfs dentry */ | |
49 | struct ovl_entry { | |
50 | struct dentry *__upperdentry; | |
e9be9d5e MS |
51 | struct ovl_dir_cache *cache; |
52 | union { | |
53 | struct { | |
54 | u64 version; | |
55 | bool opaque; | |
56 | }; | |
57 | struct rcu_head rcu; | |
58 | }; | |
dd662667 MS |
59 | unsigned numlower; |
60 | struct path lowerstack[]; | |
e9be9d5e MS |
61 | }; |
62 | ||
a78d9f0d MS |
63 | #define OVL_MAX_STACK 500 |
64 | ||
dd662667 MS |
65 | static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) |
66 | { | |
67 | return oe->numlower ? oe->lowerstack[0].dentry : NULL; | |
68 | } | |
e9be9d5e MS |
69 | |
70 | enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
71 | { | |
72 | struct ovl_entry *oe = dentry->d_fsdata; | |
1afaba1e | 73 | enum ovl_path_type type = 0; |
e9be9d5e MS |
74 | |
75 | if (oe->__upperdentry) { | |
1afaba1e MS |
76 | type = __OVL_PATH_UPPER; |
77 | ||
dd662667 | 78 | if (oe->numlower) { |
e9be9d5e | 79 | if (S_ISDIR(dentry->d_inode->i_mode)) |
1afaba1e MS |
80 | type |= __OVL_PATH_MERGE; |
81 | } else if (!oe->opaque) { | |
82 | type |= __OVL_PATH_PURE; | |
e9be9d5e | 83 | } |
9d7459d8 MS |
84 | } else { |
85 | if (oe->numlower > 1) | |
86 | type |= __OVL_PATH_MERGE; | |
e9be9d5e | 87 | } |
1afaba1e | 88 | return type; |
e9be9d5e MS |
89 | } |
90 | ||
91 | static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) | |
92 | { | |
71d50928 | 93 | return lockless_dereference(oe->__upperdentry); |
e9be9d5e MS |
94 | } |
95 | ||
96 | void ovl_path_upper(struct dentry *dentry, struct path *path) | |
97 | { | |
98 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
99 | struct ovl_entry *oe = dentry->d_fsdata; | |
100 | ||
101 | path->mnt = ofs->upper_mnt; | |
102 | path->dentry = ovl_upperdentry_dereference(oe); | |
103 | } | |
104 | ||
105 | enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
106 | { | |
e9be9d5e MS |
107 | enum ovl_path_type type = ovl_path_type(dentry); |
108 | ||
1afaba1e | 109 | if (!OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
110 | ovl_path_lower(dentry, path); |
111 | else | |
112 | ovl_path_upper(dentry, path); | |
113 | ||
114 | return type; | |
115 | } | |
116 | ||
117 | struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
118 | { | |
119 | struct ovl_entry *oe = dentry->d_fsdata; | |
120 | ||
121 | return ovl_upperdentry_dereference(oe); | |
122 | } | |
123 | ||
124 | struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
125 | { | |
126 | struct ovl_entry *oe = dentry->d_fsdata; | |
127 | ||
dd662667 | 128 | return __ovl_dentry_lower(oe); |
e9be9d5e MS |
129 | } |
130 | ||
131 | struct dentry *ovl_dentry_real(struct dentry *dentry) | |
132 | { | |
133 | struct ovl_entry *oe = dentry->d_fsdata; | |
134 | struct dentry *realdentry; | |
135 | ||
136 | realdentry = ovl_upperdentry_dereference(oe); | |
137 | if (!realdentry) | |
dd662667 | 138 | realdentry = __ovl_dentry_lower(oe); |
e9be9d5e MS |
139 | |
140 | return realdentry; | |
141 | } | |
142 | ||
143 | struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper) | |
144 | { | |
145 | struct dentry *realdentry; | |
146 | ||
147 | realdentry = ovl_upperdentry_dereference(oe); | |
148 | if (realdentry) { | |
149 | *is_upper = true; | |
150 | } else { | |
dd662667 | 151 | realdentry = __ovl_dentry_lower(oe); |
e9be9d5e MS |
152 | *is_upper = false; |
153 | } | |
154 | return realdentry; | |
155 | } | |
156 | ||
157 | struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) | |
158 | { | |
159 | struct ovl_entry *oe = dentry->d_fsdata; | |
160 | ||
161 | return oe->cache; | |
162 | } | |
163 | ||
164 | void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) | |
165 | { | |
166 | struct ovl_entry *oe = dentry->d_fsdata; | |
167 | ||
168 | oe->cache = cache; | |
169 | } | |
170 | ||
171 | void ovl_path_lower(struct dentry *dentry, struct path *path) | |
172 | { | |
e9be9d5e MS |
173 | struct ovl_entry *oe = dentry->d_fsdata; |
174 | ||
dd662667 | 175 | *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; |
e9be9d5e MS |
176 | } |
177 | ||
178 | int ovl_want_write(struct dentry *dentry) | |
179 | { | |
180 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
181 | return mnt_want_write(ofs->upper_mnt); | |
182 | } | |
183 | ||
184 | void ovl_drop_write(struct dentry *dentry) | |
185 | { | |
186 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
187 | mnt_drop_write(ofs->upper_mnt); | |
188 | } | |
189 | ||
190 | struct dentry *ovl_workdir(struct dentry *dentry) | |
191 | { | |
192 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
193 | return ofs->workdir; | |
194 | } | |
195 | ||
196 | bool ovl_dentry_is_opaque(struct dentry *dentry) | |
197 | { | |
198 | struct ovl_entry *oe = dentry->d_fsdata; | |
199 | return oe->opaque; | |
200 | } | |
201 | ||
202 | void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) | |
203 | { | |
204 | struct ovl_entry *oe = dentry->d_fsdata; | |
205 | oe->opaque = opaque; | |
206 | } | |
207 | ||
208 | void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) | |
209 | { | |
210 | struct ovl_entry *oe = dentry->d_fsdata; | |
211 | ||
212 | WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex)); | |
213 | WARN_ON(oe->__upperdentry); | |
214 | BUG_ON(!upperdentry->d_inode); | |
215 | /* | |
216 | * Make sure upperdentry is consistent before making it visible to | |
217 | * ovl_upperdentry_dereference(). | |
218 | */ | |
219 | smp_wmb(); | |
220 | oe->__upperdentry = upperdentry; | |
221 | } | |
222 | ||
223 | void ovl_dentry_version_inc(struct dentry *dentry) | |
224 | { | |
225 | struct ovl_entry *oe = dentry->d_fsdata; | |
226 | ||
227 | WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
228 | oe->version++; | |
229 | } | |
230 | ||
231 | u64 ovl_dentry_version_get(struct dentry *dentry) | |
232 | { | |
233 | struct ovl_entry *oe = dentry->d_fsdata; | |
234 | ||
235 | WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
236 | return oe->version; | |
237 | } | |
238 | ||
239 | bool ovl_is_whiteout(struct dentry *dentry) | |
240 | { | |
241 | struct inode *inode = dentry->d_inode; | |
242 | ||
243 | return inode && IS_WHITEOUT(inode); | |
244 | } | |
245 | ||
246 | static bool ovl_is_opaquedir(struct dentry *dentry) | |
247 | { | |
248 | int res; | |
249 | char val; | |
250 | struct inode *inode = dentry->d_inode; | |
251 | ||
252 | if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr) | |
253 | return false; | |
254 | ||
cead89bb | 255 | res = inode->i_op->getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1); |
e9be9d5e MS |
256 | if (res == 1 && val == 'y') |
257 | return true; | |
258 | ||
259 | return false; | |
260 | } | |
261 | ||
262 | static void ovl_dentry_release(struct dentry *dentry) | |
263 | { | |
264 | struct ovl_entry *oe = dentry->d_fsdata; | |
265 | ||
266 | if (oe) { | |
dd662667 MS |
267 | unsigned int i; |
268 | ||
e9be9d5e | 269 | dput(oe->__upperdentry); |
dd662667 MS |
270 | for (i = 0; i < oe->numlower; i++) |
271 | dput(oe->lowerstack[i].dentry); | |
e9be9d5e MS |
272 | kfree_rcu(oe, rcu); |
273 | } | |
274 | } | |
275 | ||
7c03b5d4 MS |
276 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
277 | { | |
278 | struct ovl_entry *oe = dentry->d_fsdata; | |
279 | unsigned int i; | |
280 | int ret = 1; | |
281 | ||
282 | for (i = 0; i < oe->numlower; i++) { | |
283 | struct dentry *d = oe->lowerstack[i].dentry; | |
284 | ||
285 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
286 | ret = d->d_op->d_revalidate(d, flags); | |
287 | if (ret < 0) | |
288 | return ret; | |
289 | if (!ret) { | |
290 | if (!(flags & LOOKUP_RCU)) | |
291 | d_invalidate(d); | |
292 | return -ESTALE; | |
293 | } | |
294 | } | |
295 | } | |
296 | return 1; | |
297 | } | |
298 | ||
299 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
300 | { | |
301 | struct ovl_entry *oe = dentry->d_fsdata; | |
302 | unsigned int i; | |
303 | int ret = 1; | |
304 | ||
305 | for (i = 0; i < oe->numlower; i++) { | |
306 | struct dentry *d = oe->lowerstack[i].dentry; | |
307 | ||
308 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
309 | ret = d->d_op->d_weak_revalidate(d, flags); | |
310 | if (ret <= 0) | |
311 | break; | |
312 | } | |
313 | } | |
314 | return ret; | |
315 | } | |
316 | ||
e9be9d5e MS |
317 | static const struct dentry_operations ovl_dentry_operations = { |
318 | .d_release = ovl_dentry_release, | |
4bacc9c9 | 319 | .d_select_inode = ovl_d_select_inode, |
e9be9d5e MS |
320 | }; |
321 | ||
7c03b5d4 MS |
322 | static const struct dentry_operations ovl_reval_dentry_operations = { |
323 | .d_release = ovl_dentry_release, | |
324 | .d_revalidate = ovl_dentry_revalidate, | |
325 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
326 | }; | |
327 | ||
dd662667 | 328 | static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) |
e9be9d5e | 329 | { |
dd662667 MS |
330 | size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); |
331 | struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); | |
332 | ||
333 | if (oe) | |
334 | oe->numlower = numlower; | |
335 | ||
336 | return oe; | |
e9be9d5e MS |
337 | } |
338 | ||
7c03b5d4 MS |
339 | static bool ovl_dentry_remote(struct dentry *dentry) |
340 | { | |
341 | return dentry->d_flags & | |
342 | (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); | |
343 | } | |
344 | ||
345 | static bool ovl_dentry_weird(struct dentry *dentry) | |
346 | { | |
347 | return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | | |
348 | DCACHE_MANAGE_TRANSIT | | |
349 | DCACHE_OP_HASH | | |
350 | DCACHE_OP_COMPARE); | |
351 | } | |
352 | ||
e9be9d5e MS |
353 | static inline struct dentry *ovl_lookup_real(struct dentry *dir, |
354 | struct qstr *name) | |
355 | { | |
356 | struct dentry *dentry; | |
357 | ||
358 | mutex_lock(&dir->d_inode->i_mutex); | |
359 | dentry = lookup_one_len(name->name, dir, name->len); | |
360 | mutex_unlock(&dir->d_inode->i_mutex); | |
361 | ||
362 | if (IS_ERR(dentry)) { | |
363 | if (PTR_ERR(dentry) == -ENOENT) | |
364 | dentry = NULL; | |
365 | } else if (!dentry->d_inode) { | |
366 | dput(dentry); | |
367 | dentry = NULL; | |
7c03b5d4 | 368 | } else if (ovl_dentry_weird(dentry)) { |
a6f15d9a | 369 | dput(dentry); |
7c03b5d4 | 370 | /* Don't support traversing automounts and other weirdness */ |
a6f15d9a | 371 | dentry = ERR_PTR(-EREMOTE); |
e9be9d5e MS |
372 | } |
373 | return dentry; | |
374 | } | |
375 | ||
5ef88da5 MS |
376 | /* |
377 | * Returns next layer in stack starting from top. | |
378 | * Returns -1 if this is the last layer. | |
379 | */ | |
380 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path) | |
381 | { | |
382 | struct ovl_entry *oe = dentry->d_fsdata; | |
383 | ||
384 | BUG_ON(idx < 0); | |
385 | if (idx == 0) { | |
386 | ovl_path_upper(dentry, path); | |
387 | if (path->dentry) | |
388 | return oe->numlower ? 1 : -1; | |
389 | idx++; | |
390 | } | |
391 | BUG_ON(idx > oe->numlower); | |
392 | *path = oe->lowerstack[idx - 1]; | |
393 | ||
394 | return (idx < oe->numlower) ? idx + 1 : -1; | |
395 | } | |
396 | ||
e9be9d5e MS |
397 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
398 | unsigned int flags) | |
399 | { | |
400 | struct ovl_entry *oe; | |
3d3c6b89 MS |
401 | struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
402 | struct path *stack = NULL; | |
403 | struct dentry *upperdir, *upperdentry = NULL; | |
404 | unsigned int ctr = 0; | |
e9be9d5e | 405 | struct inode *inode = NULL; |
3d3c6b89 MS |
406 | bool upperopaque = false; |
407 | struct dentry *this, *prev = NULL; | |
408 | unsigned int i; | |
e9be9d5e MS |
409 | int err; |
410 | ||
3d3c6b89 | 411 | upperdir = ovl_upperdentry_dereference(poe); |
e9be9d5e | 412 | if (upperdir) { |
3d3c6b89 MS |
413 | this = ovl_lookup_real(upperdir, &dentry->d_name); |
414 | err = PTR_ERR(this); | |
415 | if (IS_ERR(this)) | |
416 | goto out; | |
417 | ||
3e01cee3 | 418 | if (this) { |
7c03b5d4 MS |
419 | if (unlikely(ovl_dentry_remote(this))) { |
420 | dput(this); | |
421 | err = -EREMOTE; | |
422 | goto out; | |
423 | } | |
3d3c6b89 MS |
424 | if (ovl_is_whiteout(this)) { |
425 | dput(this); | |
426 | this = NULL; | |
427 | upperopaque = true; | |
3e01cee3 | 428 | } else if (poe->numlower && ovl_is_opaquedir(this)) { |
3d3c6b89 | 429 | upperopaque = true; |
e9be9d5e MS |
430 | } |
431 | } | |
3d3c6b89 | 432 | upperdentry = prev = this; |
e9be9d5e | 433 | } |
3d3c6b89 MS |
434 | |
435 | if (!upperopaque && poe->numlower) { | |
436 | err = -ENOMEM; | |
437 | stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); | |
438 | if (!stack) | |
439 | goto out_put_upper; | |
e9be9d5e MS |
440 | } |
441 | ||
3d3c6b89 MS |
442 | for (i = 0; !upperopaque && i < poe->numlower; i++) { |
443 | bool opaque = false; | |
444 | struct path lowerpath = poe->lowerstack[i]; | |
445 | ||
3d3c6b89 MS |
446 | this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name); |
447 | err = PTR_ERR(this); | |
09e10322 MS |
448 | if (IS_ERR(this)) { |
449 | /* | |
450 | * If it's positive, then treat ENAMETOOLONG as ENOENT. | |
451 | */ | |
452 | if (err == -ENAMETOOLONG && (upperdentry || ctr)) | |
453 | continue; | |
3d3c6b89 | 454 | goto out_put; |
09e10322 | 455 | } |
3d3c6b89 MS |
456 | if (!this) |
457 | continue; | |
3e01cee3 MS |
458 | if (ovl_is_whiteout(this)) { |
459 | dput(this); | |
460 | break; | |
461 | } | |
3d3c6b89 | 462 | /* |
3e01cee3 MS |
463 | * Only makes sense to check opaque dir if this is not the |
464 | * lowermost layer. | |
3d3c6b89 | 465 | */ |
3e01cee3 MS |
466 | if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) |
467 | opaque = true; | |
a425c037 | 468 | |
469 | if (prev && (!S_ISDIR(prev->d_inode->i_mode) || | |
470 | !S_ISDIR(this->d_inode->i_mode))) { | |
471 | /* | |
472 | * FIXME: check for upper-opaqueness maybe better done | |
473 | * in remove code. | |
474 | */ | |
3d3c6b89 MS |
475 | if (prev == upperdentry) |
476 | upperopaque = true; | |
477 | dput(this); | |
478 | break; | |
479 | } | |
a425c037 | 480 | /* |
481 | * If this is a non-directory then stop here. | |
482 | */ | |
483 | if (!S_ISDIR(this->d_inode->i_mode)) | |
484 | opaque = true; | |
485 | ||
3d3c6b89 MS |
486 | stack[ctr].dentry = this; |
487 | stack[ctr].mnt = lowerpath.mnt; | |
488 | ctr++; | |
489 | prev = this; | |
490 | if (opaque) | |
491 | break; | |
e9be9d5e MS |
492 | } |
493 | ||
3d3c6b89 MS |
494 | oe = ovl_alloc_entry(ctr); |
495 | err = -ENOMEM; | |
496 | if (!oe) | |
497 | goto out_put; | |
498 | ||
499 | if (upperdentry || ctr) { | |
e9be9d5e MS |
500 | struct dentry *realdentry; |
501 | ||
3d3c6b89 MS |
502 | realdentry = upperdentry ? upperdentry : stack[0].dentry; |
503 | ||
e9be9d5e MS |
504 | err = -ENOMEM; |
505 | inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode, | |
506 | oe); | |
507 | if (!inode) | |
3d3c6b89 | 508 | goto out_free_oe; |
e9be9d5e MS |
509 | ovl_copyattr(realdentry->d_inode, inode); |
510 | } | |
511 | ||
3d3c6b89 | 512 | oe->opaque = upperopaque; |
e9be9d5e | 513 | oe->__upperdentry = upperdentry; |
3d3c6b89 MS |
514 | memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); |
515 | kfree(stack); | |
e9be9d5e MS |
516 | dentry->d_fsdata = oe; |
517 | d_add(dentry, inode); | |
518 | ||
519 | return NULL; | |
520 | ||
3d3c6b89 | 521 | out_free_oe: |
e9be9d5e | 522 | kfree(oe); |
3d3c6b89 MS |
523 | out_put: |
524 | for (i = 0; i < ctr; i++) | |
525 | dput(stack[i].dentry); | |
526 | kfree(stack); | |
527 | out_put_upper: | |
528 | dput(upperdentry); | |
e9be9d5e MS |
529 | out: |
530 | return ERR_PTR(err); | |
531 | } | |
532 | ||
533 | struct file *ovl_path_open(struct path *path, int flags) | |
534 | { | |
535 | return dentry_open(path, flags, current_cred()); | |
536 | } | |
537 | ||
538 | static void ovl_put_super(struct super_block *sb) | |
539 | { | |
540 | struct ovl_fs *ufs = sb->s_fs_info; | |
dd662667 | 541 | unsigned i; |
e9be9d5e MS |
542 | |
543 | dput(ufs->workdir); | |
544 | mntput(ufs->upper_mnt); | |
dd662667 MS |
545 | for (i = 0; i < ufs->numlower; i++) |
546 | mntput(ufs->lower_mnt[i]); | |
e9be9d5e | 547 | |
f45827e8 EZ |
548 | kfree(ufs->config.lowerdir); |
549 | kfree(ufs->config.upperdir); | |
550 | kfree(ufs->config.workdir); | |
e9be9d5e MS |
551 | kfree(ufs); |
552 | } | |
553 | ||
cc259639 AW |
554 | /** |
555 | * ovl_statfs | |
556 | * @sb: The overlayfs super block | |
557 | * @buf: The struct kstatfs to fill in with stats | |
558 | * | |
559 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 560 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
561 | */ |
562 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
563 | { | |
564 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
565 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
566 | struct path path; | |
567 | int err; | |
568 | ||
4ebc5818 | 569 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
570 | |
571 | err = vfs_statfs(&path, buf); | |
572 | if (!err) { | |
573 | buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); | |
574 | buf->f_type = OVERLAYFS_SUPER_MAGIC; | |
575 | } | |
576 | ||
577 | return err; | |
578 | } | |
579 | ||
f45827e8 EZ |
580 | /** |
581 | * ovl_show_options | |
582 | * | |
583 | * Prints the mount options for a given superblock. | |
584 | * Returns zero; does not fail. | |
585 | */ | |
586 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
587 | { | |
588 | struct super_block *sb = dentry->d_sb; | |
589 | struct ovl_fs *ufs = sb->s_fs_info; | |
590 | ||
a068acf2 | 591 | seq_show_option(m, "lowerdir", ufs->config.lowerdir); |
53a08cb9 | 592 | if (ufs->config.upperdir) { |
a068acf2 KC |
593 | seq_show_option(m, "upperdir", ufs->config.upperdir); |
594 | seq_show_option(m, "workdir", ufs->config.workdir); | |
53a08cb9 | 595 | } |
f45827e8 EZ |
596 | return 0; |
597 | } | |
598 | ||
3cdf6fe9 SL |
599 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
600 | { | |
601 | struct ovl_fs *ufs = sb->s_fs_info; | |
602 | ||
cc6f67bc | 603 | if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) |
3cdf6fe9 SL |
604 | return -EROFS; |
605 | ||
606 | return 0; | |
607 | } | |
608 | ||
e9be9d5e MS |
609 | static const struct super_operations ovl_super_operations = { |
610 | .put_super = ovl_put_super, | |
cc259639 | 611 | .statfs = ovl_statfs, |
f45827e8 | 612 | .show_options = ovl_show_options, |
3cdf6fe9 | 613 | .remount_fs = ovl_remount, |
e9be9d5e MS |
614 | }; |
615 | ||
616 | enum { | |
617 | OPT_LOWERDIR, | |
618 | OPT_UPPERDIR, | |
619 | OPT_WORKDIR, | |
620 | OPT_ERR, | |
621 | }; | |
622 | ||
623 | static const match_table_t ovl_tokens = { | |
624 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
625 | {OPT_UPPERDIR, "upperdir=%s"}, | |
626 | {OPT_WORKDIR, "workdir=%s"}, | |
627 | {OPT_ERR, NULL} | |
628 | }; | |
629 | ||
91c77947 MS |
630 | static char *ovl_next_opt(char **s) |
631 | { | |
632 | char *sbegin = *s; | |
633 | char *p; | |
634 | ||
635 | if (sbegin == NULL) | |
636 | return NULL; | |
637 | ||
638 | for (p = sbegin; *p; p++) { | |
639 | if (*p == '\\') { | |
640 | p++; | |
641 | if (!*p) | |
642 | break; | |
643 | } else if (*p == ',') { | |
644 | *p = '\0'; | |
645 | *s = p + 1; | |
646 | return sbegin; | |
647 | } | |
648 | } | |
649 | *s = NULL; | |
650 | return sbegin; | |
651 | } | |
652 | ||
e9be9d5e MS |
653 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
654 | { | |
655 | char *p; | |
656 | ||
91c77947 | 657 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
658 | int token; |
659 | substring_t args[MAX_OPT_ARGS]; | |
660 | ||
661 | if (!*p) | |
662 | continue; | |
663 | ||
664 | token = match_token(p, ovl_tokens, args); | |
665 | switch (token) { | |
666 | case OPT_UPPERDIR: | |
667 | kfree(config->upperdir); | |
668 | config->upperdir = match_strdup(&args[0]); | |
669 | if (!config->upperdir) | |
670 | return -ENOMEM; | |
671 | break; | |
672 | ||
673 | case OPT_LOWERDIR: | |
674 | kfree(config->lowerdir); | |
675 | config->lowerdir = match_strdup(&args[0]); | |
676 | if (!config->lowerdir) | |
677 | return -ENOMEM; | |
678 | break; | |
679 | ||
680 | case OPT_WORKDIR: | |
681 | kfree(config->workdir); | |
682 | config->workdir = match_strdup(&args[0]); | |
683 | if (!config->workdir) | |
684 | return -ENOMEM; | |
685 | break; | |
686 | ||
687 | default: | |
bead55ef | 688 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
689 | return -EINVAL; |
690 | } | |
691 | } | |
71cbad7e | 692 | |
693 | /* Workdir is useless in non-upper mount */ | |
694 | if (!config->upperdir && config->workdir) { | |
695 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
696 | config->workdir); | |
697 | kfree(config->workdir); | |
698 | config->workdir = NULL; | |
699 | } | |
700 | ||
e9be9d5e MS |
701 | return 0; |
702 | } | |
703 | ||
704 | #define OVL_WORKDIR_NAME "work" | |
705 | ||
706 | static struct dentry *ovl_workdir_create(struct vfsmount *mnt, | |
707 | struct dentry *dentry) | |
708 | { | |
709 | struct inode *dir = dentry->d_inode; | |
710 | struct dentry *work; | |
711 | int err; | |
712 | bool retried = false; | |
713 | ||
714 | err = mnt_want_write(mnt); | |
715 | if (err) | |
716 | return ERR_PTR(err); | |
717 | ||
718 | mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT); | |
719 | retry: | |
720 | work = lookup_one_len(OVL_WORKDIR_NAME, dentry, | |
721 | strlen(OVL_WORKDIR_NAME)); | |
722 | ||
723 | if (!IS_ERR(work)) { | |
724 | struct kstat stat = { | |
725 | .mode = S_IFDIR | 0, | |
726 | }; | |
727 | ||
728 | if (work->d_inode) { | |
729 | err = -EEXIST; | |
730 | if (retried) | |
731 | goto out_dput; | |
732 | ||
733 | retried = true; | |
734 | ovl_cleanup(dir, work); | |
735 | dput(work); | |
736 | goto retry; | |
737 | } | |
738 | ||
739 | err = ovl_create_real(dir, work, &stat, NULL, NULL, true); | |
740 | if (err) | |
741 | goto out_dput; | |
742 | } | |
743 | out_unlock: | |
744 | mutex_unlock(&dir->i_mutex); | |
745 | mnt_drop_write(mnt); | |
746 | ||
747 | return work; | |
748 | ||
749 | out_dput: | |
750 | dput(work); | |
751 | work = ERR_PTR(err); | |
752 | goto out_unlock; | |
753 | } | |
754 | ||
91c77947 MS |
755 | static void ovl_unescape(char *s) |
756 | { | |
757 | char *d = s; | |
758 | ||
759 | for (;; s++, d++) { | |
760 | if (*s == '\\') | |
761 | s++; | |
762 | *d = *s; | |
763 | if (!*s) | |
764 | break; | |
765 | } | |
766 | } | |
767 | ||
ab508822 MS |
768 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
769 | { | |
a78d9f0d | 770 | int err = -EINVAL; |
ab508822 | 771 | |
a78d9f0d MS |
772 | if (!*name) { |
773 | pr_err("overlayfs: empty lowerdir\n"); | |
774 | goto out; | |
775 | } | |
ab508822 MS |
776 | err = kern_path(name, LOOKUP_FOLLOW, path); |
777 | if (err) { | |
778 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
779 | goto out; | |
780 | } | |
781 | err = -EINVAL; | |
7c03b5d4 | 782 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
783 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
784 | goto out_put; | |
785 | } | |
786 | if (!S_ISDIR(path->dentry->d_inode->i_mode)) { | |
787 | pr_err("overlayfs: '%s' not a directory\n", name); | |
788 | goto out_put; | |
789 | } | |
790 | return 0; | |
791 | ||
792 | out_put: | |
793 | path_put(path); | |
794 | out: | |
795 | return err; | |
796 | } | |
797 | ||
798 | static int ovl_mount_dir(const char *name, struct path *path) | |
799 | { | |
800 | int err = -ENOMEM; | |
801 | char *tmp = kstrdup(name, GFP_KERNEL); | |
802 | ||
803 | if (tmp) { | |
804 | ovl_unescape(tmp); | |
805 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
806 | |
807 | if (!err) | |
808 | if (ovl_dentry_remote(path->dentry)) { | |
809 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
810 | tmp); | |
811 | path_put(path); | |
812 | err = -EINVAL; | |
813 | } | |
ab508822 MS |
814 | kfree(tmp); |
815 | } | |
816 | return err; | |
817 | } | |
818 | ||
819 | static int ovl_lower_dir(const char *name, struct path *path, long *namelen, | |
7c03b5d4 | 820 | int *stack_depth, bool *remote) |
ab508822 MS |
821 | { |
822 | int err; | |
823 | struct kstatfs statfs; | |
824 | ||
a78d9f0d | 825 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
826 | if (err) |
827 | goto out; | |
828 | ||
829 | err = vfs_statfs(path, &statfs); | |
830 | if (err) { | |
831 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
832 | goto out_put; | |
833 | } | |
834 | *namelen = max(*namelen, statfs.f_namelen); | |
835 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); | |
836 | ||
7c03b5d4 MS |
837 | if (ovl_dentry_remote(path->dentry)) |
838 | *remote = true; | |
839 | ||
ab508822 MS |
840 | return 0; |
841 | ||
842 | out_put: | |
843 | path_put(path); | |
844 | out: | |
845 | return err; | |
846 | } | |
847 | ||
e9be9d5e MS |
848 | /* Workdir should not be subdir of upperdir and vice versa */ |
849 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
850 | { | |
851 | bool ok = false; | |
852 | ||
853 | if (workdir != upperdir) { | |
854 | ok = (lock_rename(workdir, upperdir) == NULL); | |
855 | unlock_rename(workdir, upperdir); | |
856 | } | |
857 | return ok; | |
858 | } | |
859 | ||
a78d9f0d MS |
860 | static unsigned int ovl_split_lowerdirs(char *str) |
861 | { | |
862 | unsigned int ctr = 1; | |
863 | char *s, *d; | |
864 | ||
865 | for (s = d = str;; s++, d++) { | |
866 | if (*s == '\\') { | |
867 | s++; | |
868 | } else if (*s == ':') { | |
869 | *d = '\0'; | |
870 | ctr++; | |
871 | continue; | |
872 | } | |
873 | *d = *s; | |
874 | if (!*s) | |
875 | break; | |
876 | } | |
877 | return ctr; | |
878 | } | |
879 | ||
e9be9d5e MS |
880 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
881 | { | |
53a08cb9 MS |
882 | struct path upperpath = { NULL, NULL }; |
883 | struct path workpath = { NULL, NULL }; | |
e9be9d5e MS |
884 | struct dentry *root_dentry; |
885 | struct ovl_entry *oe; | |
886 | struct ovl_fs *ufs; | |
a78d9f0d MS |
887 | struct path *stack = NULL; |
888 | char *lowertmp; | |
889 | char *lower; | |
890 | unsigned int numlower; | |
891 | unsigned int stacklen = 0; | |
dd662667 | 892 | unsigned int i; |
7c03b5d4 | 893 | bool remote = false; |
e9be9d5e MS |
894 | int err; |
895 | ||
f45827e8 EZ |
896 | err = -ENOMEM; |
897 | ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
898 | if (!ufs) | |
e9be9d5e MS |
899 | goto out; |
900 | ||
f45827e8 EZ |
901 | err = ovl_parse_opt((char *) data, &ufs->config); |
902 | if (err) | |
903 | goto out_free_config; | |
904 | ||
e9be9d5e | 905 | err = -EINVAL; |
53a08cb9 MS |
906 | if (!ufs->config.lowerdir) { |
907 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
e9be9d5e MS |
908 | goto out_free_config; |
909 | } | |
910 | ||
53a08cb9 MS |
911 | sb->s_stack_depth = 0; |
912 | if (ufs->config.upperdir) { | |
53a08cb9 MS |
913 | if (!ufs->config.workdir) { |
914 | pr_err("overlayfs: missing 'workdir'\n"); | |
915 | goto out_free_config; | |
916 | } | |
e9be9d5e | 917 | |
53a08cb9 MS |
918 | err = ovl_mount_dir(ufs->config.upperdir, &upperpath); |
919 | if (err) | |
920 | goto out_free_config; | |
e9be9d5e | 921 | |
71cbad7e | 922 | /* Upper fs should not be r/o */ |
923 | if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { | |
924 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
925 | err = -EINVAL; | |
926 | goto out_put_upperpath; | |
927 | } | |
928 | ||
53a08cb9 MS |
929 | err = ovl_mount_dir(ufs->config.workdir, &workpath); |
930 | if (err) | |
931 | goto out_put_upperpath; | |
932 | ||
2f83fd8c | 933 | err = -EINVAL; |
53a08cb9 MS |
934 | if (upperpath.mnt != workpath.mnt) { |
935 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); | |
936 | goto out_put_workpath; | |
937 | } | |
938 | if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) { | |
939 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); | |
940 | goto out_put_workpath; | |
941 | } | |
942 | sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth; | |
cc259639 | 943 | } |
a78d9f0d MS |
944 | err = -ENOMEM; |
945 | lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL); | |
946 | if (!lowertmp) | |
ab508822 | 947 | goto out_put_workpath; |
69c433ed | 948 | |
a78d9f0d MS |
949 | err = -EINVAL; |
950 | stacklen = ovl_split_lowerdirs(lowertmp); | |
6be4506e | 951 | if (stacklen > OVL_MAX_STACK) { |
952 | pr_err("overlayfs: too many lower directries, limit is %d\n", | |
953 | OVL_MAX_STACK); | |
a78d9f0d | 954 | goto out_free_lowertmp; |
6be4506e | 955 | } else if (!ufs->config.upperdir && stacklen == 1) { |
956 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); | |
957 | goto out_free_lowertmp; | |
958 | } | |
a78d9f0d MS |
959 | |
960 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); | |
961 | if (!stack) | |
962 | goto out_free_lowertmp; | |
963 | ||
964 | lower = lowertmp; | |
965 | for (numlower = 0; numlower < stacklen; numlower++) { | |
966 | err = ovl_lower_dir(lower, &stack[numlower], | |
7c03b5d4 MS |
967 | &ufs->lower_namelen, &sb->s_stack_depth, |
968 | &remote); | |
a78d9f0d MS |
969 | if (err) |
970 | goto out_put_lowerpath; | |
971 | ||
972 | lower = strchr(lower, '\0') + 1; | |
973 | } | |
974 | ||
69c433ed | 975 | err = -EINVAL; |
ab508822 | 976 | sb->s_stack_depth++; |
69c433ed MS |
977 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
978 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
3b7a9a24 | 979 | goto out_put_lowerpath; |
69c433ed MS |
980 | } |
981 | ||
53a08cb9 MS |
982 | if (ufs->config.upperdir) { |
983 | ufs->upper_mnt = clone_private_mount(&upperpath); | |
984 | err = PTR_ERR(ufs->upper_mnt); | |
985 | if (IS_ERR(ufs->upper_mnt)) { | |
986 | pr_err("overlayfs: failed to clone upperpath\n"); | |
987 | goto out_put_lowerpath; | |
988 | } | |
3b7a9a24 | 989 | |
53a08cb9 MS |
990 | ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); |
991 | err = PTR_ERR(ufs->workdir); | |
992 | if (IS_ERR(ufs->workdir)) { | |
cc6f67bc MS |
993 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
994 | ufs->config.workdir, OVL_WORKDIR_NAME, -err); | |
995 | sb->s_flags |= MS_RDONLY; | |
996 | ufs->workdir = NULL; | |
53a08cb9 | 997 | } |
e9be9d5e MS |
998 | } |
999 | ||
2f83fd8c | 1000 | err = -ENOMEM; |
a78d9f0d | 1001 | ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); |
dd662667 | 1002 | if (ufs->lower_mnt == NULL) |
3b7a9a24 | 1003 | goto out_put_workdir; |
a78d9f0d MS |
1004 | for (i = 0; i < numlower; i++) { |
1005 | struct vfsmount *mnt = clone_private_mount(&stack[i]); | |
dd662667 | 1006 | |
2f83fd8c | 1007 | err = PTR_ERR(mnt); |
a78d9f0d MS |
1008 | if (IS_ERR(mnt)) { |
1009 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
1010 | goto out_put_lower_mnt; | |
1011 | } | |
1012 | /* | |
1013 | * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
1014 | * will fail instead of modifying lower fs. | |
1015 | */ | |
1016 | mnt->mnt_flags |= MNT_READONLY; | |
dd662667 | 1017 | |
a78d9f0d MS |
1018 | ufs->lower_mnt[ufs->numlower] = mnt; |
1019 | ufs->numlower++; | |
1020 | } | |
e9be9d5e | 1021 | |
71cbad7e | 1022 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
1023 | if (!ufs->upper_mnt) | |
e9be9d5e MS |
1024 | sb->s_flags |= MS_RDONLY; |
1025 | ||
7c03b5d4 MS |
1026 | if (remote) |
1027 | sb->s_d_op = &ovl_reval_dentry_operations; | |
1028 | else | |
1029 | sb->s_d_op = &ovl_dentry_operations; | |
e9be9d5e MS |
1030 | |
1031 | err = -ENOMEM; | |
a78d9f0d | 1032 | oe = ovl_alloc_entry(numlower); |
3b7a9a24 MS |
1033 | if (!oe) |
1034 | goto out_put_lower_mnt; | |
e9be9d5e | 1035 | |
3b7a9a24 | 1036 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, oe)); |
e9be9d5e | 1037 | if (!root_dentry) |
3b7a9a24 | 1038 | goto out_free_oe; |
e9be9d5e MS |
1039 | |
1040 | mntput(upperpath.mnt); | |
a78d9f0d MS |
1041 | for (i = 0; i < numlower; i++) |
1042 | mntput(stack[i].mnt); | |
e9be9d5e | 1043 | path_put(&workpath); |
a78d9f0d | 1044 | kfree(lowertmp); |
e9be9d5e MS |
1045 | |
1046 | oe->__upperdentry = upperpath.dentry; | |
a78d9f0d MS |
1047 | for (i = 0; i < numlower; i++) { |
1048 | oe->lowerstack[i].dentry = stack[i].dentry; | |
1049 | oe->lowerstack[i].mnt = ufs->lower_mnt[i]; | |
1050 | } | |
e9be9d5e MS |
1051 | |
1052 | root_dentry->d_fsdata = oe; | |
1053 | ||
cc259639 | 1054 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
e9be9d5e MS |
1055 | sb->s_op = &ovl_super_operations; |
1056 | sb->s_root = root_dentry; | |
1057 | sb->s_fs_info = ufs; | |
1058 | ||
1059 | return 0; | |
1060 | ||
3b7a9a24 MS |
1061 | out_free_oe: |
1062 | kfree(oe); | |
e9be9d5e | 1063 | out_put_lower_mnt: |
dd662667 MS |
1064 | for (i = 0; i < ufs->numlower; i++) |
1065 | mntput(ufs->lower_mnt[i]); | |
1066 | kfree(ufs->lower_mnt); | |
3b7a9a24 MS |
1067 | out_put_workdir: |
1068 | dput(ufs->workdir); | |
e9be9d5e | 1069 | mntput(ufs->upper_mnt); |
e9be9d5e | 1070 | out_put_lowerpath: |
a78d9f0d MS |
1071 | for (i = 0; i < numlower; i++) |
1072 | path_put(&stack[i]); | |
1073 | kfree(stack); | |
1074 | out_free_lowertmp: | |
1075 | kfree(lowertmp); | |
3b7a9a24 MS |
1076 | out_put_workpath: |
1077 | path_put(&workpath); | |
e9be9d5e MS |
1078 | out_put_upperpath: |
1079 | path_put(&upperpath); | |
e9be9d5e | 1080 | out_free_config: |
f45827e8 EZ |
1081 | kfree(ufs->config.lowerdir); |
1082 | kfree(ufs->config.upperdir); | |
1083 | kfree(ufs->config.workdir); | |
1084 | kfree(ufs); | |
e9be9d5e MS |
1085 | out: |
1086 | return err; | |
1087 | } | |
1088 | ||
1089 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
1090 | const char *dev_name, void *raw_data) | |
1091 | { | |
1092 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
1093 | } | |
1094 | ||
1095 | static struct file_system_type ovl_fs_type = { | |
1096 | .owner = THIS_MODULE, | |
ef94b186 | 1097 | .name = "overlay", |
e9be9d5e MS |
1098 | .mount = ovl_mount, |
1099 | .kill_sb = kill_anon_super, | |
1100 | }; | |
ef94b186 | 1101 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e MS |
1102 | |
1103 | static int __init ovl_init(void) | |
1104 | { | |
1105 | return register_filesystem(&ovl_fs_type); | |
1106 | } | |
1107 | ||
1108 | static void __exit ovl_exit(void) | |
1109 | { | |
1110 | unregister_filesystem(&ovl_fs_type); | |
1111 | } | |
1112 | ||
1113 | module_init(ovl_init); | |
1114 | module_exit(ovl_exit); |