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; | |
cdb67279 | 26 | struct ovl_cache_entry *next_maybe_whiteout; |
c2096537 | 27 | bool is_whiteout; |
68bf8611 | 28 | char name[]; |
e9be9d5e MS |
29 | }; |
30 | ||
31 | struct ovl_dir_cache { | |
32 | long refcount; | |
33 | u64 version; | |
34 | struct list_head entries; | |
35 | }; | |
36 | ||
37 | struct ovl_readdir_data { | |
38 | struct dir_context ctx; | |
39 | bool is_merge; | |
49be4fb9 | 40 | struct rb_root root; |
e9be9d5e | 41 | struct list_head *list; |
db6ec212 | 42 | struct list_head middle; |
cdb67279 | 43 | struct ovl_cache_entry *first_maybe_whiteout; |
e9be9d5e MS |
44 | int count; |
45 | int err; | |
46 | }; | |
47 | ||
48 | struct ovl_dir_file { | |
49 | bool is_real; | |
50 | bool is_upper; | |
51 | struct ovl_dir_cache *cache; | |
4330397e | 52 | struct list_head *cursor; |
e9be9d5e MS |
53 | struct file *realfile; |
54 | struct file *upperfile; | |
55 | }; | |
56 | ||
57 | static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) | |
58 | { | |
59 | return container_of(n, struct ovl_cache_entry, node); | |
60 | } | |
61 | ||
62 | static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, | |
63 | const char *name, int len) | |
64 | { | |
65 | struct rb_node *node = root->rb_node; | |
66 | int cmp; | |
67 | ||
68 | while (node) { | |
69 | struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); | |
70 | ||
71 | cmp = strncmp(name, p->name, len); | |
72 | if (cmp > 0) | |
73 | node = p->node.rb_right; | |
74 | else if (cmp < 0 || len < p->len) | |
75 | node = p->node.rb_left; | |
76 | else | |
77 | return p; | |
78 | } | |
79 | ||
80 | return NULL; | |
81 | } | |
82 | ||
cdb67279 | 83 | static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd, |
3e01cee3 | 84 | const char *name, int len, |
e9be9d5e MS |
85 | u64 ino, unsigned int d_type) |
86 | { | |
87 | struct ovl_cache_entry *p; | |
68bf8611 | 88 | size_t size = offsetof(struct ovl_cache_entry, name[len + 1]); |
e9be9d5e | 89 | |
68bf8611 | 90 | p = kmalloc(size, GFP_KERNEL); |
3e01cee3 MS |
91 | if (!p) |
92 | return NULL; | |
93 | ||
94 | memcpy(p->name, name, len); | |
95 | p->name[len] = '\0'; | |
96 | p->len = len; | |
97 | p->type = d_type; | |
98 | p->ino = ino; | |
99 | p->is_whiteout = false; | |
3e01cee3 MS |
100 | |
101 | if (d_type == DT_CHR) { | |
cdb67279 MS |
102 | p->next_maybe_whiteout = rdd->first_maybe_whiteout; |
103 | rdd->first_maybe_whiteout = p; | |
3e01cee3 | 104 | } |
e9be9d5e MS |
105 | return p; |
106 | } | |
107 | ||
108 | static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, | |
109 | const char *name, int len, u64 ino, | |
110 | unsigned int d_type) | |
111 | { | |
49be4fb9 | 112 | struct rb_node **newp = &rdd->root.rb_node; |
e9be9d5e MS |
113 | struct rb_node *parent = NULL; |
114 | struct ovl_cache_entry *p; | |
115 | ||
116 | while (*newp) { | |
117 | int cmp; | |
118 | struct ovl_cache_entry *tmp; | |
119 | ||
120 | parent = *newp; | |
121 | tmp = ovl_cache_entry_from_node(*newp); | |
122 | cmp = strncmp(name, tmp->name, len); | |
123 | if (cmp > 0) | |
124 | newp = &tmp->node.rb_right; | |
125 | else if (cmp < 0 || len < tmp->len) | |
126 | newp = &tmp->node.rb_left; | |
127 | else | |
128 | return 0; | |
129 | } | |
130 | ||
cdb67279 | 131 | p = ovl_cache_entry_new(rdd, name, len, ino, d_type); |
e9be9d5e MS |
132 | if (p == NULL) |
133 | return -ENOMEM; | |
134 | ||
135 | list_add_tail(&p->l_node, rdd->list); | |
136 | rb_link_node(&p->node, parent, newp); | |
49be4fb9 | 137 | rb_insert_color(&p->node, &rdd->root); |
e9be9d5e MS |
138 | |
139 | return 0; | |
140 | } | |
141 | ||
142 | static int ovl_fill_lower(struct ovl_readdir_data *rdd, | |
143 | const char *name, int namelen, | |
144 | loff_t offset, u64 ino, unsigned int d_type) | |
145 | { | |
146 | struct ovl_cache_entry *p; | |
147 | ||
49be4fb9 | 148 | p = ovl_cache_entry_find(&rdd->root, name, namelen); |
e9be9d5e | 149 | if (p) { |
db6ec212 | 150 | list_move_tail(&p->l_node, &rdd->middle); |
e9be9d5e | 151 | } else { |
cdb67279 | 152 | p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type); |
e9be9d5e MS |
153 | if (p == NULL) |
154 | rdd->err = -ENOMEM; | |
155 | else | |
db6ec212 | 156 | list_add_tail(&p->l_node, &rdd->middle); |
e9be9d5e MS |
157 | } |
158 | ||
159 | return rdd->err; | |
160 | } | |
161 | ||
162 | void ovl_cache_free(struct list_head *list) | |
163 | { | |
164 | struct ovl_cache_entry *p; | |
165 | struct ovl_cache_entry *n; | |
166 | ||
167 | list_for_each_entry_safe(p, n, list, l_node) | |
168 | kfree(p); | |
169 | ||
170 | INIT_LIST_HEAD(list); | |
171 | } | |
172 | ||
173 | static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry) | |
174 | { | |
175 | struct ovl_dir_cache *cache = od->cache; | |
176 | ||
e9be9d5e MS |
177 | WARN_ON(cache->refcount <= 0); |
178 | cache->refcount--; | |
179 | if (!cache->refcount) { | |
180 | if (ovl_dir_cache(dentry) == cache) | |
181 | ovl_set_dir_cache(dentry, NULL); | |
182 | ||
183 | ovl_cache_free(&cache->entries); | |
184 | kfree(cache); | |
185 | } | |
186 | } | |
187 | ||
ac7576f4 MS |
188 | static int ovl_fill_merge(struct dir_context *ctx, const char *name, |
189 | int namelen, loff_t offset, u64 ino, | |
190 | unsigned int d_type) | |
e9be9d5e | 191 | { |
ac7576f4 MS |
192 | struct ovl_readdir_data *rdd = |
193 | container_of(ctx, struct ovl_readdir_data, ctx); | |
e9be9d5e MS |
194 | |
195 | rdd->count++; | |
196 | if (!rdd->is_merge) | |
197 | return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); | |
198 | else | |
199 | return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type); | |
200 | } | |
201 | ||
cdb67279 MS |
202 | static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd) |
203 | { | |
204 | int err; | |
205 | struct ovl_cache_entry *p; | |
206 | struct dentry *dentry; | |
207 | const struct cred *old_cred; | |
208 | struct cred *override_cred; | |
209 | ||
210 | override_cred = prepare_creds(); | |
211 | if (!override_cred) | |
212 | return -ENOMEM; | |
213 | ||
214 | /* | |
215 | * CAP_DAC_OVERRIDE for lookup | |
216 | */ | |
217 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
218 | old_cred = override_creds(override_cred); | |
219 | ||
220 | err = mutex_lock_killable(&dir->d_inode->i_mutex); | |
221 | if (!err) { | |
222 | while (rdd->first_maybe_whiteout) { | |
223 | p = rdd->first_maybe_whiteout; | |
224 | rdd->first_maybe_whiteout = p->next_maybe_whiteout; | |
225 | dentry = lookup_one_len(p->name, dir, p->len); | |
226 | if (!IS_ERR(dentry)) { | |
227 | p->is_whiteout = ovl_is_whiteout(dentry); | |
228 | dput(dentry); | |
229 | } | |
230 | } | |
231 | mutex_unlock(&dir->d_inode->i_mutex); | |
232 | } | |
233 | revert_creds(old_cred); | |
234 | put_cred(override_cred); | |
235 | ||
236 | return err; | |
237 | } | |
238 | ||
e9be9d5e MS |
239 | static inline int ovl_dir_read(struct path *realpath, |
240 | struct ovl_readdir_data *rdd) | |
241 | { | |
242 | struct file *realfile; | |
243 | int err; | |
244 | ||
245 | realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); | |
246 | if (IS_ERR(realfile)) | |
247 | return PTR_ERR(realfile); | |
248 | ||
cdb67279 | 249 | rdd->first_maybe_whiteout = NULL; |
e9be9d5e MS |
250 | rdd->ctx.pos = 0; |
251 | do { | |
252 | rdd->count = 0; | |
253 | rdd->err = 0; | |
254 | err = iterate_dir(realfile, &rdd->ctx); | |
255 | if (err >= 0) | |
256 | err = rdd->err; | |
257 | } while (!err && rdd->count); | |
cdb67279 MS |
258 | |
259 | if (!err && rdd->first_maybe_whiteout) | |
260 | err = ovl_check_whiteouts(realpath->dentry, rdd); | |
261 | ||
e9be9d5e MS |
262 | fput(realfile); |
263 | ||
264 | return err; | |
265 | } | |
266 | ||
267 | static void ovl_dir_reset(struct file *file) | |
268 | { | |
269 | struct ovl_dir_file *od = file->private_data; | |
270 | struct ovl_dir_cache *cache = od->cache; | |
271 | struct dentry *dentry = file->f_path.dentry; | |
272 | enum ovl_path_type type = ovl_path_type(dentry); | |
273 | ||
274 | if (cache && ovl_dentry_version_get(dentry) != cache->version) { | |
275 | ovl_cache_put(od, dentry); | |
276 | od->cache = NULL; | |
4330397e | 277 | od->cursor = NULL; |
e9be9d5e | 278 | } |
1afaba1e MS |
279 | WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type)); |
280 | if (od->is_real && OVL_TYPE_MERGE(type)) | |
e9be9d5e MS |
281 | od->is_real = false; |
282 | } | |
283 | ||
c9f00fdb | 284 | static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) |
e9be9d5e MS |
285 | { |
286 | int err; | |
9d7459d8 | 287 | struct path realpath; |
e9be9d5e MS |
288 | struct ovl_readdir_data rdd = { |
289 | .ctx.actor = ovl_fill_merge, | |
290 | .list = list, | |
49be4fb9 | 291 | .root = RB_ROOT, |
e9be9d5e MS |
292 | .is_merge = false, |
293 | }; | |
9d7459d8 | 294 | int idx, next; |
e9be9d5e | 295 | |
9d7459d8 MS |
296 | for (idx = 0; idx != -1; idx = next) { |
297 | next = ovl_path_next(idx, dentry, &realpath); | |
c9f00fdb | 298 | |
9d7459d8 | 299 | if (next != -1) { |
9d7459d8 | 300 | err = ovl_dir_read(&realpath, &rdd); |
e9be9d5e | 301 | if (err) |
9d7459d8 MS |
302 | break; |
303 | } else { | |
304 | /* | |
305 | * Insert lowest layer entries before upper ones, this | |
306 | * allows offsets to be reasonably constant | |
307 | */ | |
308 | list_add(&rdd.middle, rdd.list); | |
309 | rdd.is_merge = true; | |
310 | err = ovl_dir_read(&realpath, &rdd); | |
311 | list_del(&rdd.middle); | |
e9be9d5e MS |
312 | } |
313 | } | |
e9be9d5e | 314 | return err; |
e9be9d5e MS |
315 | } |
316 | ||
317 | static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) | |
318 | { | |
4330397e | 319 | struct list_head *p; |
e9be9d5e MS |
320 | loff_t off = 0; |
321 | ||
4330397e | 322 | list_for_each(p, &od->cache->entries) { |
e9be9d5e MS |
323 | if (off >= pos) |
324 | break; | |
325 | off++; | |
326 | } | |
4330397e | 327 | /* Cursor is safe since the cache is stable */ |
328 | od->cursor = p; | |
e9be9d5e MS |
329 | } |
330 | ||
331 | static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) | |
332 | { | |
333 | int res; | |
e9be9d5e MS |
334 | struct ovl_dir_cache *cache; |
335 | ||
336 | cache = ovl_dir_cache(dentry); | |
337 | if (cache && ovl_dentry_version_get(dentry) == cache->version) { | |
338 | cache->refcount++; | |
339 | return cache; | |
340 | } | |
341 | ovl_set_dir_cache(dentry, NULL); | |
342 | ||
343 | cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL); | |
344 | if (!cache) | |
345 | return ERR_PTR(-ENOMEM); | |
346 | ||
347 | cache->refcount = 1; | |
348 | INIT_LIST_HEAD(&cache->entries); | |
349 | ||
c9f00fdb | 350 | res = ovl_dir_read_merged(dentry, &cache->entries); |
e9be9d5e MS |
351 | if (res) { |
352 | ovl_cache_free(&cache->entries); | |
353 | kfree(cache); | |
354 | return ERR_PTR(res); | |
355 | } | |
356 | ||
357 | cache->version = ovl_dentry_version_get(dentry); | |
358 | ovl_set_dir_cache(dentry, cache); | |
359 | ||
360 | return cache; | |
361 | } | |
362 | ||
363 | static int ovl_iterate(struct file *file, struct dir_context *ctx) | |
364 | { | |
365 | struct ovl_dir_file *od = file->private_data; | |
366 | struct dentry *dentry = file->f_path.dentry; | |
4330397e | 367 | struct ovl_cache_entry *p; |
e9be9d5e MS |
368 | |
369 | if (!ctx->pos) | |
370 | ovl_dir_reset(file); | |
371 | ||
372 | if (od->is_real) | |
373 | return iterate_dir(od->realfile, ctx); | |
374 | ||
375 | if (!od->cache) { | |
376 | struct ovl_dir_cache *cache; | |
377 | ||
378 | cache = ovl_cache_get(dentry); | |
379 | if (IS_ERR(cache)) | |
380 | return PTR_ERR(cache); | |
381 | ||
382 | od->cache = cache; | |
383 | ovl_seek_cursor(od, ctx->pos); | |
384 | } | |
385 | ||
4330397e | 386 | while (od->cursor != &od->cache->entries) { |
387 | p = list_entry(od->cursor, struct ovl_cache_entry, l_node); | |
388 | if (!p->is_whiteout) | |
389 | if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) | |
390 | break; | |
391 | od->cursor = p->l_node.next; | |
392 | ctx->pos++; | |
e9be9d5e MS |
393 | } |
394 | return 0; | |
395 | } | |
396 | ||
397 | static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) | |
398 | { | |
399 | loff_t res; | |
400 | struct ovl_dir_file *od = file->private_data; | |
401 | ||
402 | mutex_lock(&file_inode(file)->i_mutex); | |
403 | if (!file->f_pos) | |
404 | ovl_dir_reset(file); | |
405 | ||
406 | if (od->is_real) { | |
407 | res = vfs_llseek(od->realfile, offset, origin); | |
408 | file->f_pos = od->realfile->f_pos; | |
409 | } else { | |
410 | res = -EINVAL; | |
411 | ||
412 | switch (origin) { | |
413 | case SEEK_CUR: | |
414 | offset += file->f_pos; | |
415 | break; | |
416 | case SEEK_SET: | |
417 | break; | |
418 | default: | |
419 | goto out_unlock; | |
420 | } | |
421 | if (offset < 0) | |
422 | goto out_unlock; | |
423 | ||
424 | if (offset != file->f_pos) { | |
425 | file->f_pos = offset; | |
426 | if (od->cache) | |
427 | ovl_seek_cursor(od, offset); | |
428 | } | |
429 | res = offset; | |
430 | } | |
431 | out_unlock: | |
432 | mutex_unlock(&file_inode(file)->i_mutex); | |
433 | ||
434 | return res; | |
435 | } | |
436 | ||
437 | static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, | |
438 | int datasync) | |
439 | { | |
440 | struct ovl_dir_file *od = file->private_data; | |
441 | struct dentry *dentry = file->f_path.dentry; | |
442 | struct file *realfile = od->realfile; | |
443 | ||
444 | /* | |
445 | * Need to check if we started out being a lower dir, but got copied up | |
446 | */ | |
1afaba1e | 447 | if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) { |
e9be9d5e MS |
448 | struct inode *inode = file_inode(file); |
449 | ||
7676895f | 450 | realfile = lockless_dereference(od->upperfile); |
e9be9d5e MS |
451 | if (!realfile) { |
452 | struct path upperpath; | |
453 | ||
454 | ovl_path_upper(dentry, &upperpath); | |
455 | realfile = ovl_path_open(&upperpath, O_RDONLY); | |
d45f00ae | 456 | smp_mb__before_spinlock(); |
3d268c9b AV |
457 | mutex_lock(&inode->i_mutex); |
458 | if (!od->upperfile) { | |
459 | if (IS_ERR(realfile)) { | |
460 | mutex_unlock(&inode->i_mutex); | |
461 | return PTR_ERR(realfile); | |
462 | } | |
463 | od->upperfile = realfile; | |
464 | } else { | |
465 | /* somebody has beaten us to it */ | |
466 | if (!IS_ERR(realfile)) | |
467 | fput(realfile); | |
468 | realfile = od->upperfile; | |
e9be9d5e | 469 | } |
3d268c9b | 470 | mutex_unlock(&inode->i_mutex); |
e9be9d5e | 471 | } |
e9be9d5e MS |
472 | } |
473 | ||
474 | return vfs_fsync_range(realfile, start, end, datasync); | |
475 | } | |
476 | ||
477 | static int ovl_dir_release(struct inode *inode, struct file *file) | |
478 | { | |
479 | struct ovl_dir_file *od = file->private_data; | |
480 | ||
481 | if (od->cache) { | |
482 | mutex_lock(&inode->i_mutex); | |
483 | ovl_cache_put(od, file->f_path.dentry); | |
484 | mutex_unlock(&inode->i_mutex); | |
485 | } | |
486 | fput(od->realfile); | |
487 | if (od->upperfile) | |
488 | fput(od->upperfile); | |
489 | kfree(od); | |
490 | ||
491 | return 0; | |
492 | } | |
493 | ||
494 | static int ovl_dir_open(struct inode *inode, struct file *file) | |
495 | { | |
496 | struct path realpath; | |
497 | struct file *realfile; | |
498 | struct ovl_dir_file *od; | |
499 | enum ovl_path_type type; | |
500 | ||
501 | od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); | |
502 | if (!od) | |
503 | return -ENOMEM; | |
504 | ||
505 | type = ovl_path_real(file->f_path.dentry, &realpath); | |
506 | realfile = ovl_path_open(&realpath, file->f_flags); | |
507 | if (IS_ERR(realfile)) { | |
508 | kfree(od); | |
509 | return PTR_ERR(realfile); | |
510 | } | |
e9be9d5e | 511 | od->realfile = realfile; |
1afaba1e MS |
512 | od->is_real = !OVL_TYPE_MERGE(type); |
513 | od->is_upper = OVL_TYPE_UPPER(type); | |
e9be9d5e MS |
514 | file->private_data = od; |
515 | ||
516 | return 0; | |
517 | } | |
518 | ||
519 | const struct file_operations ovl_dir_operations = { | |
520 | .read = generic_read_dir, | |
521 | .open = ovl_dir_open, | |
522 | .iterate = ovl_iterate, | |
523 | .llseek = ovl_dir_llseek, | |
524 | .fsync = ovl_dir_fsync, | |
525 | .release = ovl_dir_release, | |
526 | }; | |
527 | ||
528 | int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) | |
529 | { | |
530 | int err; | |
e9be9d5e MS |
531 | struct ovl_cache_entry *p; |
532 | ||
c9f00fdb | 533 | err = ovl_dir_read_merged(dentry, list); |
e9be9d5e MS |
534 | if (err) |
535 | return err; | |
536 | ||
537 | err = 0; | |
538 | ||
539 | list_for_each_entry(p, list, l_node) { | |
540 | if (p->is_whiteout) | |
541 | continue; | |
542 | ||
543 | if (p->name[0] == '.') { | |
544 | if (p->len == 1) | |
545 | continue; | |
546 | if (p->len == 2 && p->name[1] == '.') | |
547 | continue; | |
548 | } | |
549 | err = -ENOTEMPTY; | |
550 | break; | |
551 | } | |
552 | ||
553 | return err; | |
554 | } | |
555 | ||
556 | void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) | |
557 | { | |
558 | struct ovl_cache_entry *p; | |
559 | ||
d1b72cc6 | 560 | mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD); |
e9be9d5e MS |
561 | list_for_each_entry(p, list, l_node) { |
562 | struct dentry *dentry; | |
563 | ||
564 | if (!p->is_whiteout) | |
565 | continue; | |
566 | ||
567 | dentry = lookup_one_len(p->name, upper, p->len); | |
568 | if (IS_ERR(dentry)) { | |
569 | pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n", | |
570 | upper->d_name.name, p->len, p->name, | |
571 | (int) PTR_ERR(dentry)); | |
572 | continue; | |
573 | } | |
574 | ovl_cleanup(upper->d_inode, dentry); | |
575 | dput(dentry); | |
576 | } | |
577 | mutex_unlock(&upper->d_inode->i_mutex); | |
578 | } |