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/slab.h> | |
12 | #include <linux/namei.h> | |
13 | #include <linux/file.h> | |
14 | #include <linux/xattr.h> | |
15 | #include <linux/rbtree.h> | |
16 | #include <linux/security.h> | |
17 | #include <linux/cred.h> | |
18 | #include "overlayfs.h" | |
19 | ||
20 | struct ovl_cache_entry { | |
e9be9d5e MS |
21 | unsigned int len; |
22 | unsigned int type; | |
23 | u64 ino; | |
e9be9d5e MS |
24 | struct list_head l_node; |
25 | struct rb_node node; | |
c2096537 | 26 | bool is_whiteout; |
68bf8611 | 27 | char name[]; |
e9be9d5e MS |
28 | }; |
29 | ||
30 | struct ovl_dir_cache { | |
31 | long refcount; | |
32 | u64 version; | |
33 | struct list_head entries; | |
34 | }; | |
35 | ||
36 | struct ovl_readdir_data { | |
37 | struct dir_context ctx; | |
38 | bool is_merge; | |
49be4fb9 | 39 | struct rb_root root; |
e9be9d5e | 40 | struct list_head *list; |
db6ec212 | 41 | struct list_head middle; |
49c21e1c | 42 | struct dentry *dir; |
e9be9d5e MS |
43 | int count; |
44 | int err; | |
45 | }; | |
46 | ||
47 | struct ovl_dir_file { | |
48 | bool is_real; | |
49 | bool is_upper; | |
50 | struct ovl_dir_cache *cache; | |
4330397e | 51 | struct list_head *cursor; |
e9be9d5e MS |
52 | struct file *realfile; |
53 | struct file *upperfile; | |
54 | }; | |
55 | ||
56 | static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) | |
57 | { | |
58 | return container_of(n, struct ovl_cache_entry, node); | |
59 | } | |
60 | ||
61 | static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, | |
62 | const char *name, int len) | |
63 | { | |
64 | struct rb_node *node = root->rb_node; | |
65 | int cmp; | |
66 | ||
67 | while (node) { | |
68 | struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); | |
69 | ||
70 | cmp = strncmp(name, p->name, len); | |
71 | if (cmp > 0) | |
72 | node = p->node.rb_right; | |
73 | else if (cmp < 0 || len < p->len) | |
74 | node = p->node.rb_left; | |
75 | else | |
76 | return p; | |
77 | } | |
78 | ||
79 | return NULL; | |
80 | } | |
81 | ||
3e01cee3 MS |
82 | static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir, |
83 | const char *name, int len, | |
e9be9d5e MS |
84 | u64 ino, unsigned int d_type) |
85 | { | |
86 | struct ovl_cache_entry *p; | |
68bf8611 | 87 | size_t size = offsetof(struct ovl_cache_entry, name[len + 1]); |
e9be9d5e | 88 | |
68bf8611 | 89 | p = kmalloc(size, GFP_KERNEL); |
3e01cee3 MS |
90 | if (!p) |
91 | return NULL; | |
92 | ||
93 | memcpy(p->name, name, len); | |
94 | p->name[len] = '\0'; | |
95 | p->len = len; | |
96 | p->type = d_type; | |
97 | p->ino = ino; | |
98 | p->is_whiteout = false; | |
3e01cee3 MS |
99 | |
100 | if (d_type == DT_CHR) { | |
101 | struct dentry *dentry; | |
102 | const struct cred *old_cred; | |
103 | struct cred *override_cred; | |
104 | ||
105 | override_cred = prepare_creds(); | |
106 | if (!override_cred) { | |
107 | kfree(p); | |
108 | return NULL; | |
109 | } | |
e9be9d5e | 110 | |
3e01cee3 MS |
111 | /* |
112 | * CAP_DAC_OVERRIDE for lookup | |
113 | */ | |
114 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
115 | old_cred = override_creds(override_cred); | |
116 | ||
117 | dentry = lookup_one_len(name, dir, len); | |
118 | if (!IS_ERR(dentry)) { | |
119 | p->is_whiteout = ovl_is_whiteout(dentry); | |
120 | dput(dentry); | |
121 | } | |
122 | revert_creds(old_cred); | |
123 | put_cred(override_cred); | |
124 | } | |
e9be9d5e MS |
125 | return p; |
126 | } | |
127 | ||
128 | static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, | |
129 | const char *name, int len, u64 ino, | |
130 | unsigned int d_type) | |
131 | { | |
49be4fb9 | 132 | struct rb_node **newp = &rdd->root.rb_node; |
e9be9d5e MS |
133 | struct rb_node *parent = NULL; |
134 | struct ovl_cache_entry *p; | |
135 | ||
136 | while (*newp) { | |
137 | int cmp; | |
138 | struct ovl_cache_entry *tmp; | |
139 | ||
140 | parent = *newp; | |
141 | tmp = ovl_cache_entry_from_node(*newp); | |
142 | cmp = strncmp(name, tmp->name, len); | |
143 | if (cmp > 0) | |
144 | newp = &tmp->node.rb_right; | |
145 | else if (cmp < 0 || len < tmp->len) | |
146 | newp = &tmp->node.rb_left; | |
147 | else | |
148 | return 0; | |
149 | } | |
150 | ||
3e01cee3 | 151 | p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type); |
e9be9d5e MS |
152 | if (p == NULL) |
153 | return -ENOMEM; | |
154 | ||
155 | list_add_tail(&p->l_node, rdd->list); | |
156 | rb_link_node(&p->node, parent, newp); | |
49be4fb9 | 157 | rb_insert_color(&p->node, &rdd->root); |
e9be9d5e MS |
158 | |
159 | return 0; | |
160 | } | |
161 | ||
162 | static int ovl_fill_lower(struct ovl_readdir_data *rdd, | |
163 | const char *name, int namelen, | |
164 | loff_t offset, u64 ino, unsigned int d_type) | |
165 | { | |
166 | struct ovl_cache_entry *p; | |
167 | ||
49be4fb9 | 168 | p = ovl_cache_entry_find(&rdd->root, name, namelen); |
e9be9d5e | 169 | if (p) { |
db6ec212 | 170 | list_move_tail(&p->l_node, &rdd->middle); |
e9be9d5e | 171 | } else { |
3e01cee3 | 172 | p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type); |
e9be9d5e MS |
173 | if (p == NULL) |
174 | rdd->err = -ENOMEM; | |
175 | else | |
db6ec212 | 176 | list_add_tail(&p->l_node, &rdd->middle); |
e9be9d5e MS |
177 | } |
178 | ||
179 | return rdd->err; | |
180 | } | |
181 | ||
182 | void ovl_cache_free(struct list_head *list) | |
183 | { | |
184 | struct ovl_cache_entry *p; | |
185 | struct ovl_cache_entry *n; | |
186 | ||
187 | list_for_each_entry_safe(p, n, list, l_node) | |
188 | kfree(p); | |
189 | ||
190 | INIT_LIST_HEAD(list); | |
191 | } | |
192 | ||
193 | static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry) | |
194 | { | |
195 | struct ovl_dir_cache *cache = od->cache; | |
196 | ||
e9be9d5e MS |
197 | WARN_ON(cache->refcount <= 0); |
198 | cache->refcount--; | |
199 | if (!cache->refcount) { | |
200 | if (ovl_dir_cache(dentry) == cache) | |
201 | ovl_set_dir_cache(dentry, NULL); | |
202 | ||
203 | ovl_cache_free(&cache->entries); | |
204 | kfree(cache); | |
205 | } | |
206 | } | |
207 | ||
ac7576f4 MS |
208 | static int ovl_fill_merge(struct dir_context *ctx, const char *name, |
209 | int namelen, loff_t offset, u64 ino, | |
210 | unsigned int d_type) | |
e9be9d5e | 211 | { |
ac7576f4 MS |
212 | struct ovl_readdir_data *rdd = |
213 | container_of(ctx, struct ovl_readdir_data, ctx); | |
e9be9d5e MS |
214 | |
215 | rdd->count++; | |
216 | if (!rdd->is_merge) | |
217 | return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); | |
218 | else | |
219 | return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type); | |
220 | } | |
221 | ||
222 | static inline int ovl_dir_read(struct path *realpath, | |
223 | struct ovl_readdir_data *rdd) | |
224 | { | |
225 | struct file *realfile; | |
226 | int err; | |
227 | ||
228 | realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); | |
229 | if (IS_ERR(realfile)) | |
230 | return PTR_ERR(realfile); | |
231 | ||
3e01cee3 | 232 | rdd->dir = realpath->dentry; |
e9be9d5e MS |
233 | rdd->ctx.pos = 0; |
234 | do { | |
235 | rdd->count = 0; | |
236 | rdd->err = 0; | |
237 | err = iterate_dir(realfile, &rdd->ctx); | |
238 | if (err >= 0) | |
239 | err = rdd->err; | |
240 | } while (!err && rdd->count); | |
241 | fput(realfile); | |
242 | ||
243 | return err; | |
244 | } | |
245 | ||
246 | static void ovl_dir_reset(struct file *file) | |
247 | { | |
248 | struct ovl_dir_file *od = file->private_data; | |
249 | struct ovl_dir_cache *cache = od->cache; | |
250 | struct dentry *dentry = file->f_path.dentry; | |
251 | enum ovl_path_type type = ovl_path_type(dentry); | |
252 | ||
253 | if (cache && ovl_dentry_version_get(dentry) != cache->version) { | |
254 | ovl_cache_put(od, dentry); | |
255 | od->cache = NULL; | |
4330397e | 256 | od->cursor = NULL; |
e9be9d5e | 257 | } |
1afaba1e MS |
258 | WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type)); |
259 | if (od->is_real && OVL_TYPE_MERGE(type)) | |
e9be9d5e MS |
260 | od->is_real = false; |
261 | } | |
262 | ||
c9f00fdb | 263 | static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) |
e9be9d5e MS |
264 | { |
265 | int err; | |
9d7459d8 | 266 | struct path realpath; |
e9be9d5e MS |
267 | struct ovl_readdir_data rdd = { |
268 | .ctx.actor = ovl_fill_merge, | |
269 | .list = list, | |
49be4fb9 | 270 | .root = RB_ROOT, |
e9be9d5e MS |
271 | .is_merge = false, |
272 | }; | |
9d7459d8 | 273 | int idx, next; |
e9be9d5e | 274 | |
9d7459d8 MS |
275 | for (idx = 0; idx != -1; idx = next) { |
276 | next = ovl_path_next(idx, dentry, &realpath); | |
c9f00fdb | 277 | |
9d7459d8 | 278 | if (next != -1) { |
9d7459d8 | 279 | err = ovl_dir_read(&realpath, &rdd); |
e9be9d5e | 280 | if (err) |
9d7459d8 MS |
281 | break; |
282 | } else { | |
283 | /* | |
284 | * Insert lowest layer entries before upper ones, this | |
285 | * allows offsets to be reasonably constant | |
286 | */ | |
287 | list_add(&rdd.middle, rdd.list); | |
288 | rdd.is_merge = true; | |
289 | err = ovl_dir_read(&realpath, &rdd); | |
290 | list_del(&rdd.middle); | |
e9be9d5e MS |
291 | } |
292 | } | |
e9be9d5e | 293 | return err; |
e9be9d5e MS |
294 | } |
295 | ||
296 | static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) | |
297 | { | |
4330397e | 298 | struct list_head *p; |
e9be9d5e MS |
299 | loff_t off = 0; |
300 | ||
4330397e | 301 | list_for_each(p, &od->cache->entries) { |
e9be9d5e MS |
302 | if (off >= pos) |
303 | break; | |
304 | off++; | |
305 | } | |
4330397e | 306 | /* Cursor is safe since the cache is stable */ |
307 | od->cursor = p; | |
e9be9d5e MS |
308 | } |
309 | ||
310 | static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) | |
311 | { | |
312 | int res; | |
e9be9d5e MS |
313 | struct ovl_dir_cache *cache; |
314 | ||
315 | cache = ovl_dir_cache(dentry); | |
316 | if (cache && ovl_dentry_version_get(dentry) == cache->version) { | |
317 | cache->refcount++; | |
318 | return cache; | |
319 | } | |
320 | ovl_set_dir_cache(dentry, NULL); | |
321 | ||
322 | cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL); | |
323 | if (!cache) | |
324 | return ERR_PTR(-ENOMEM); | |
325 | ||
326 | cache->refcount = 1; | |
327 | INIT_LIST_HEAD(&cache->entries); | |
328 | ||
c9f00fdb | 329 | res = ovl_dir_read_merged(dentry, &cache->entries); |
e9be9d5e MS |
330 | if (res) { |
331 | ovl_cache_free(&cache->entries); | |
332 | kfree(cache); | |
333 | return ERR_PTR(res); | |
334 | } | |
335 | ||
336 | cache->version = ovl_dentry_version_get(dentry); | |
337 | ovl_set_dir_cache(dentry, cache); | |
338 | ||
339 | return cache; | |
340 | } | |
341 | ||
342 | static int ovl_iterate(struct file *file, struct dir_context *ctx) | |
343 | { | |
344 | struct ovl_dir_file *od = file->private_data; | |
345 | struct dentry *dentry = file->f_path.dentry; | |
4330397e | 346 | struct ovl_cache_entry *p; |
e9be9d5e MS |
347 | |
348 | if (!ctx->pos) | |
349 | ovl_dir_reset(file); | |
350 | ||
351 | if (od->is_real) | |
352 | return iterate_dir(od->realfile, ctx); | |
353 | ||
354 | if (!od->cache) { | |
355 | struct ovl_dir_cache *cache; | |
356 | ||
357 | cache = ovl_cache_get(dentry); | |
358 | if (IS_ERR(cache)) | |
359 | return PTR_ERR(cache); | |
360 | ||
361 | od->cache = cache; | |
362 | ovl_seek_cursor(od, ctx->pos); | |
363 | } | |
364 | ||
4330397e | 365 | while (od->cursor != &od->cache->entries) { |
366 | p = list_entry(od->cursor, struct ovl_cache_entry, l_node); | |
367 | if (!p->is_whiteout) | |
368 | if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) | |
369 | break; | |
370 | od->cursor = p->l_node.next; | |
371 | ctx->pos++; | |
e9be9d5e MS |
372 | } |
373 | return 0; | |
374 | } | |
375 | ||
376 | static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) | |
377 | { | |
378 | loff_t res; | |
379 | struct ovl_dir_file *od = file->private_data; | |
380 | ||
381 | mutex_lock(&file_inode(file)->i_mutex); | |
382 | if (!file->f_pos) | |
383 | ovl_dir_reset(file); | |
384 | ||
385 | if (od->is_real) { | |
386 | res = vfs_llseek(od->realfile, offset, origin); | |
387 | file->f_pos = od->realfile->f_pos; | |
388 | } else { | |
389 | res = -EINVAL; | |
390 | ||
391 | switch (origin) { | |
392 | case SEEK_CUR: | |
393 | offset += file->f_pos; | |
394 | break; | |
395 | case SEEK_SET: | |
396 | break; | |
397 | default: | |
398 | goto out_unlock; | |
399 | } | |
400 | if (offset < 0) | |
401 | goto out_unlock; | |
402 | ||
403 | if (offset != file->f_pos) { | |
404 | file->f_pos = offset; | |
405 | if (od->cache) | |
406 | ovl_seek_cursor(od, offset); | |
407 | } | |
408 | res = offset; | |
409 | } | |
410 | out_unlock: | |
411 | mutex_unlock(&file_inode(file)->i_mutex); | |
412 | ||
413 | return res; | |
414 | } | |
415 | ||
416 | static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, | |
417 | int datasync) | |
418 | { | |
419 | struct ovl_dir_file *od = file->private_data; | |
420 | struct dentry *dentry = file->f_path.dentry; | |
421 | struct file *realfile = od->realfile; | |
422 | ||
423 | /* | |
424 | * Need to check if we started out being a lower dir, but got copied up | |
425 | */ | |
1afaba1e | 426 | if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) { |
e9be9d5e MS |
427 | struct inode *inode = file_inode(file); |
428 | ||
7676895f | 429 | realfile = lockless_dereference(od->upperfile); |
e9be9d5e MS |
430 | if (!realfile) { |
431 | struct path upperpath; | |
432 | ||
433 | ovl_path_upper(dentry, &upperpath); | |
434 | realfile = ovl_path_open(&upperpath, O_RDONLY); | |
d45f00ae | 435 | smp_mb__before_spinlock(); |
3d268c9b AV |
436 | mutex_lock(&inode->i_mutex); |
437 | if (!od->upperfile) { | |
438 | if (IS_ERR(realfile)) { | |
439 | mutex_unlock(&inode->i_mutex); | |
440 | return PTR_ERR(realfile); | |
441 | } | |
442 | od->upperfile = realfile; | |
443 | } else { | |
444 | /* somebody has beaten us to it */ | |
445 | if (!IS_ERR(realfile)) | |
446 | fput(realfile); | |
447 | realfile = od->upperfile; | |
e9be9d5e | 448 | } |
3d268c9b | 449 | mutex_unlock(&inode->i_mutex); |
e9be9d5e | 450 | } |
e9be9d5e MS |
451 | } |
452 | ||
453 | return vfs_fsync_range(realfile, start, end, datasync); | |
454 | } | |
455 | ||
456 | static int ovl_dir_release(struct inode *inode, struct file *file) | |
457 | { | |
458 | struct ovl_dir_file *od = file->private_data; | |
459 | ||
460 | if (od->cache) { | |
461 | mutex_lock(&inode->i_mutex); | |
462 | ovl_cache_put(od, file->f_path.dentry); | |
463 | mutex_unlock(&inode->i_mutex); | |
464 | } | |
465 | fput(od->realfile); | |
466 | if (od->upperfile) | |
467 | fput(od->upperfile); | |
468 | kfree(od); | |
469 | ||
470 | return 0; | |
471 | } | |
472 | ||
473 | static int ovl_dir_open(struct inode *inode, struct file *file) | |
474 | { | |
475 | struct path realpath; | |
476 | struct file *realfile; | |
477 | struct ovl_dir_file *od; | |
478 | enum ovl_path_type type; | |
479 | ||
480 | od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); | |
481 | if (!od) | |
482 | return -ENOMEM; | |
483 | ||
484 | type = ovl_path_real(file->f_path.dentry, &realpath); | |
485 | realfile = ovl_path_open(&realpath, file->f_flags); | |
486 | if (IS_ERR(realfile)) { | |
487 | kfree(od); | |
488 | return PTR_ERR(realfile); | |
489 | } | |
e9be9d5e | 490 | od->realfile = realfile; |
1afaba1e MS |
491 | od->is_real = !OVL_TYPE_MERGE(type); |
492 | od->is_upper = OVL_TYPE_UPPER(type); | |
e9be9d5e MS |
493 | file->private_data = od; |
494 | ||
495 | return 0; | |
496 | } | |
497 | ||
498 | const struct file_operations ovl_dir_operations = { | |
499 | .read = generic_read_dir, | |
500 | .open = ovl_dir_open, | |
501 | .iterate = ovl_iterate, | |
502 | .llseek = ovl_dir_llseek, | |
503 | .fsync = ovl_dir_fsync, | |
504 | .release = ovl_dir_release, | |
505 | }; | |
506 | ||
507 | int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) | |
508 | { | |
509 | int err; | |
e9be9d5e MS |
510 | struct ovl_cache_entry *p; |
511 | ||
c9f00fdb | 512 | err = ovl_dir_read_merged(dentry, list); |
e9be9d5e MS |
513 | if (err) |
514 | return err; | |
515 | ||
516 | err = 0; | |
517 | ||
518 | list_for_each_entry(p, list, l_node) { | |
519 | if (p->is_whiteout) | |
520 | continue; | |
521 | ||
522 | if (p->name[0] == '.') { | |
523 | if (p->len == 1) | |
524 | continue; | |
525 | if (p->len == 2 && p->name[1] == '.') | |
526 | continue; | |
527 | } | |
528 | err = -ENOTEMPTY; | |
529 | break; | |
530 | } | |
531 | ||
532 | return err; | |
533 | } | |
534 | ||
535 | void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) | |
536 | { | |
537 | struct ovl_cache_entry *p; | |
538 | ||
d1b72cc6 | 539 | mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD); |
e9be9d5e MS |
540 | list_for_each_entry(p, list, l_node) { |
541 | struct dentry *dentry; | |
542 | ||
543 | if (!p->is_whiteout) | |
544 | continue; | |
545 | ||
546 | dentry = lookup_one_len(p->name, upper, p->len); | |
547 | if (IS_ERR(dentry)) { | |
548 | pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n", | |
549 | upper->d_name.name, p->len, p->name, | |
550 | (int) PTR_ERR(dentry)); | |
551 | continue; | |
552 | } | |
553 | ovl_cleanup(upper->d_inode, dentry); | |
554 | dput(dentry); | |
555 | } | |
556 | mutex_unlock(&upper->d_inode->i_mutex); | |
557 | } |