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 MS |
26 | bool is_whiteout; |
27 | bool is_cursor; | |
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; |
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; | |
51 | struct ovl_cache_entry cursor; | |
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 | ||
82 | static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len, | |
83 | u64 ino, unsigned int d_type) | |
84 | { | |
85 | struct ovl_cache_entry *p; | |
68bf8611 | 86 | size_t size = offsetof(struct ovl_cache_entry, name[len + 1]); |
e9be9d5e | 87 | |
68bf8611 | 88 | p = kmalloc(size, GFP_KERNEL); |
e9be9d5e | 89 | if (p) { |
68bf8611 AV |
90 | memcpy(p->name, name, len); |
91 | p->name[len] = '\0'; | |
e9be9d5e MS |
92 | p->len = len; |
93 | p->type = d_type; | |
94 | p->ino = ino; | |
95 | p->is_whiteout = false; | |
9f2f7d4c | 96 | p->is_cursor = false; |
e9be9d5e MS |
97 | } |
98 | ||
99 | return p; | |
100 | } | |
101 | ||
102 | static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, | |
103 | const char *name, int len, u64 ino, | |
104 | unsigned int d_type) | |
105 | { | |
49be4fb9 | 106 | struct rb_node **newp = &rdd->root.rb_node; |
e9be9d5e MS |
107 | struct rb_node *parent = NULL; |
108 | struct ovl_cache_entry *p; | |
109 | ||
110 | while (*newp) { | |
111 | int cmp; | |
112 | struct ovl_cache_entry *tmp; | |
113 | ||
114 | parent = *newp; | |
115 | tmp = ovl_cache_entry_from_node(*newp); | |
116 | cmp = strncmp(name, tmp->name, len); | |
117 | if (cmp > 0) | |
118 | newp = &tmp->node.rb_right; | |
119 | else if (cmp < 0 || len < tmp->len) | |
120 | newp = &tmp->node.rb_left; | |
121 | else | |
122 | return 0; | |
123 | } | |
124 | ||
125 | p = ovl_cache_entry_new(name, len, ino, d_type); | |
126 | if (p == NULL) | |
127 | return -ENOMEM; | |
128 | ||
129 | list_add_tail(&p->l_node, rdd->list); | |
130 | rb_link_node(&p->node, parent, newp); | |
49be4fb9 | 131 | rb_insert_color(&p->node, &rdd->root); |
e9be9d5e MS |
132 | |
133 | return 0; | |
134 | } | |
135 | ||
136 | static int ovl_fill_lower(struct ovl_readdir_data *rdd, | |
137 | const char *name, int namelen, | |
138 | loff_t offset, u64 ino, unsigned int d_type) | |
139 | { | |
140 | struct ovl_cache_entry *p; | |
141 | ||
49be4fb9 | 142 | p = ovl_cache_entry_find(&rdd->root, name, namelen); |
e9be9d5e | 143 | if (p) { |
db6ec212 | 144 | list_move_tail(&p->l_node, &rdd->middle); |
e9be9d5e MS |
145 | } else { |
146 | p = ovl_cache_entry_new(name, namelen, ino, d_type); | |
147 | if (p == NULL) | |
148 | rdd->err = -ENOMEM; | |
149 | else | |
db6ec212 | 150 | list_add_tail(&p->l_node, &rdd->middle); |
e9be9d5e MS |
151 | } |
152 | ||
153 | return rdd->err; | |
154 | } | |
155 | ||
156 | void ovl_cache_free(struct list_head *list) | |
157 | { | |
158 | struct ovl_cache_entry *p; | |
159 | struct ovl_cache_entry *n; | |
160 | ||
161 | list_for_each_entry_safe(p, n, list, l_node) | |
162 | kfree(p); | |
163 | ||
164 | INIT_LIST_HEAD(list); | |
165 | } | |
166 | ||
167 | static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry) | |
168 | { | |
169 | struct ovl_dir_cache *cache = od->cache; | |
170 | ||
3f822c62 | 171 | list_del_init(&od->cursor.l_node); |
e9be9d5e MS |
172 | WARN_ON(cache->refcount <= 0); |
173 | cache->refcount--; | |
174 | if (!cache->refcount) { | |
175 | if (ovl_dir_cache(dentry) == cache) | |
176 | ovl_set_dir_cache(dentry, NULL); | |
177 | ||
178 | ovl_cache_free(&cache->entries); | |
179 | kfree(cache); | |
180 | } | |
181 | } | |
182 | ||
ac7576f4 MS |
183 | static int ovl_fill_merge(struct dir_context *ctx, const char *name, |
184 | int namelen, loff_t offset, u64 ino, | |
185 | unsigned int d_type) | |
e9be9d5e | 186 | { |
ac7576f4 MS |
187 | struct ovl_readdir_data *rdd = |
188 | container_of(ctx, struct ovl_readdir_data, ctx); | |
e9be9d5e MS |
189 | |
190 | rdd->count++; | |
191 | if (!rdd->is_merge) | |
192 | return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); | |
193 | else | |
194 | return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type); | |
195 | } | |
196 | ||
197 | static inline int ovl_dir_read(struct path *realpath, | |
198 | struct ovl_readdir_data *rdd) | |
199 | { | |
200 | struct file *realfile; | |
201 | int err; | |
202 | ||
203 | realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY); | |
204 | if (IS_ERR(realfile)) | |
205 | return PTR_ERR(realfile); | |
206 | ||
207 | rdd->ctx.pos = 0; | |
208 | do { | |
209 | rdd->count = 0; | |
210 | rdd->err = 0; | |
211 | err = iterate_dir(realfile, &rdd->ctx); | |
212 | if (err >= 0) | |
213 | err = rdd->err; | |
214 | } while (!err && rdd->count); | |
215 | fput(realfile); | |
216 | ||
217 | return err; | |
218 | } | |
219 | ||
220 | static void ovl_dir_reset(struct file *file) | |
221 | { | |
222 | struct ovl_dir_file *od = file->private_data; | |
223 | struct ovl_dir_cache *cache = od->cache; | |
224 | struct dentry *dentry = file->f_path.dentry; | |
225 | enum ovl_path_type type = ovl_path_type(dentry); | |
226 | ||
227 | if (cache && ovl_dentry_version_get(dentry) != cache->version) { | |
228 | ovl_cache_put(od, dentry); | |
229 | od->cache = NULL; | |
230 | } | |
231 | WARN_ON(!od->is_real && type != OVL_PATH_MERGE); | |
232 | if (od->is_real && type == OVL_PATH_MERGE) | |
233 | od->is_real = false; | |
234 | } | |
235 | ||
236 | static int ovl_dir_mark_whiteouts(struct dentry *dir, | |
237 | struct ovl_readdir_data *rdd) | |
238 | { | |
239 | struct ovl_cache_entry *p; | |
240 | struct dentry *dentry; | |
241 | const struct cred *old_cred; | |
242 | struct cred *override_cred; | |
243 | ||
244 | override_cred = prepare_creds(); | |
245 | if (!override_cred) { | |
246 | ovl_cache_free(rdd->list); | |
247 | return -ENOMEM; | |
248 | } | |
249 | ||
250 | /* | |
251 | * CAP_DAC_OVERRIDE for lookup | |
252 | */ | |
253 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
254 | old_cred = override_creds(override_cred); | |
255 | ||
256 | mutex_lock(&dir->d_inode->i_mutex); | |
257 | list_for_each_entry(p, rdd->list, l_node) { | |
c2096537 | 258 | if (p->is_cursor) |
e9be9d5e MS |
259 | continue; |
260 | ||
261 | if (p->type != DT_CHR) | |
262 | continue; | |
263 | ||
264 | dentry = lookup_one_len(p->name, dir, p->len); | |
265 | if (IS_ERR(dentry)) | |
266 | continue; | |
267 | ||
268 | p->is_whiteout = ovl_is_whiteout(dentry); | |
269 | dput(dentry); | |
270 | } | |
271 | mutex_unlock(&dir->d_inode->i_mutex); | |
272 | ||
273 | revert_creds(old_cred); | |
274 | put_cred(override_cred); | |
275 | ||
276 | return 0; | |
277 | } | |
278 | ||
c9f00fdb | 279 | static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) |
e9be9d5e MS |
280 | { |
281 | int err; | |
c9f00fdb MS |
282 | struct path lowerpath; |
283 | struct path upperpath; | |
e9be9d5e MS |
284 | struct ovl_readdir_data rdd = { |
285 | .ctx.actor = ovl_fill_merge, | |
286 | .list = list, | |
49be4fb9 | 287 | .root = RB_ROOT, |
e9be9d5e MS |
288 | .is_merge = false, |
289 | }; | |
290 | ||
c9f00fdb MS |
291 | ovl_path_lower(dentry, &lowerpath); |
292 | ovl_path_upper(dentry, &upperpath); | |
293 | ||
294 | if (upperpath.dentry) { | |
295 | err = ovl_dir_read(&upperpath, &rdd); | |
e9be9d5e MS |
296 | if (err) |
297 | goto out; | |
298 | ||
c9f00fdb MS |
299 | if (lowerpath.dentry) { |
300 | err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd); | |
e9be9d5e MS |
301 | if (err) |
302 | goto out; | |
303 | } | |
304 | } | |
c9f00fdb | 305 | if (lowerpath.dentry) { |
e9be9d5e MS |
306 | /* |
307 | * Insert lowerpath entries before upperpath ones, this allows | |
308 | * offsets to be reasonably constant | |
309 | */ | |
db6ec212 | 310 | list_add(&rdd.middle, rdd.list); |
e9be9d5e | 311 | rdd.is_merge = true; |
c9f00fdb | 312 | err = ovl_dir_read(&lowerpath, &rdd); |
db6ec212 | 313 | list_del(&rdd.middle); |
e9be9d5e MS |
314 | } |
315 | out: | |
316 | return err; | |
e9be9d5e MS |
317 | } |
318 | ||
319 | static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) | |
320 | { | |
321 | struct ovl_cache_entry *p; | |
322 | loff_t off = 0; | |
323 | ||
324 | list_for_each_entry(p, &od->cache->entries, l_node) { | |
c2096537 | 325 | if (p->is_cursor) |
e9be9d5e MS |
326 | continue; |
327 | if (off >= pos) | |
328 | break; | |
329 | off++; | |
330 | } | |
331 | list_move_tail(&od->cursor.l_node, &p->l_node); | |
332 | } | |
333 | ||
334 | static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) | |
335 | { | |
336 | int res; | |
e9be9d5e MS |
337 | struct ovl_dir_cache *cache; |
338 | ||
339 | cache = ovl_dir_cache(dentry); | |
340 | if (cache && ovl_dentry_version_get(dentry) == cache->version) { | |
341 | cache->refcount++; | |
342 | return cache; | |
343 | } | |
344 | ovl_set_dir_cache(dentry, NULL); | |
345 | ||
346 | cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL); | |
347 | if (!cache) | |
348 | return ERR_PTR(-ENOMEM); | |
349 | ||
350 | cache->refcount = 1; | |
351 | INIT_LIST_HEAD(&cache->entries); | |
352 | ||
c9f00fdb | 353 | res = ovl_dir_read_merged(dentry, &cache->entries); |
e9be9d5e MS |
354 | if (res) { |
355 | ovl_cache_free(&cache->entries); | |
356 | kfree(cache); | |
357 | return ERR_PTR(res); | |
358 | } | |
359 | ||
360 | cache->version = ovl_dentry_version_get(dentry); | |
361 | ovl_set_dir_cache(dentry, cache); | |
362 | ||
363 | return cache; | |
364 | } | |
365 | ||
366 | static int ovl_iterate(struct file *file, struct dir_context *ctx) | |
367 | { | |
368 | struct ovl_dir_file *od = file->private_data; | |
369 | struct dentry *dentry = file->f_path.dentry; | |
370 | ||
371 | if (!ctx->pos) | |
372 | ovl_dir_reset(file); | |
373 | ||
374 | if (od->is_real) | |
375 | return iterate_dir(od->realfile, ctx); | |
376 | ||
377 | if (!od->cache) { | |
378 | struct ovl_dir_cache *cache; | |
379 | ||
380 | cache = ovl_cache_get(dentry); | |
381 | if (IS_ERR(cache)) | |
382 | return PTR_ERR(cache); | |
383 | ||
384 | od->cache = cache; | |
385 | ovl_seek_cursor(od, ctx->pos); | |
386 | } | |
387 | ||
388 | while (od->cursor.l_node.next != &od->cache->entries) { | |
389 | struct ovl_cache_entry *p; | |
390 | ||
391 | p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node); | |
392 | /* Skip cursors */ | |
c2096537 | 393 | if (!p->is_cursor) { |
e9be9d5e MS |
394 | if (!p->is_whiteout) { |
395 | if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) | |
396 | break; | |
397 | } | |
398 | ctx->pos++; | |
399 | } | |
400 | list_move(&od->cursor.l_node, &p->l_node); | |
401 | } | |
402 | return 0; | |
403 | } | |
404 | ||
405 | static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) | |
406 | { | |
407 | loff_t res; | |
408 | struct ovl_dir_file *od = file->private_data; | |
409 | ||
410 | mutex_lock(&file_inode(file)->i_mutex); | |
411 | if (!file->f_pos) | |
412 | ovl_dir_reset(file); | |
413 | ||
414 | if (od->is_real) { | |
415 | res = vfs_llseek(od->realfile, offset, origin); | |
416 | file->f_pos = od->realfile->f_pos; | |
417 | } else { | |
418 | res = -EINVAL; | |
419 | ||
420 | switch (origin) { | |
421 | case SEEK_CUR: | |
422 | offset += file->f_pos; | |
423 | break; | |
424 | case SEEK_SET: | |
425 | break; | |
426 | default: | |
427 | goto out_unlock; | |
428 | } | |
429 | if (offset < 0) | |
430 | goto out_unlock; | |
431 | ||
432 | if (offset != file->f_pos) { | |
433 | file->f_pos = offset; | |
434 | if (od->cache) | |
435 | ovl_seek_cursor(od, offset); | |
436 | } | |
437 | res = offset; | |
438 | } | |
439 | out_unlock: | |
440 | mutex_unlock(&file_inode(file)->i_mutex); | |
441 | ||
442 | return res; | |
443 | } | |
444 | ||
445 | static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, | |
446 | int datasync) | |
447 | { | |
448 | struct ovl_dir_file *od = file->private_data; | |
449 | struct dentry *dentry = file->f_path.dentry; | |
450 | struct file *realfile = od->realfile; | |
451 | ||
452 | /* | |
453 | * Need to check if we started out being a lower dir, but got copied up | |
454 | */ | |
7676895f | 455 | if (!od->is_upper && ovl_path_type(dentry) != OVL_PATH_LOWER) { |
e9be9d5e MS |
456 | struct inode *inode = file_inode(file); |
457 | ||
7676895f | 458 | realfile = lockless_dereference(od->upperfile); |
e9be9d5e MS |
459 | if (!realfile) { |
460 | struct path upperpath; | |
461 | ||
462 | ovl_path_upper(dentry, &upperpath); | |
463 | realfile = ovl_path_open(&upperpath, O_RDONLY); | |
d45f00ae | 464 | smp_mb__before_spinlock(); |
3d268c9b AV |
465 | mutex_lock(&inode->i_mutex); |
466 | if (!od->upperfile) { | |
467 | if (IS_ERR(realfile)) { | |
468 | mutex_unlock(&inode->i_mutex); | |
469 | return PTR_ERR(realfile); | |
470 | } | |
471 | od->upperfile = realfile; | |
472 | } else { | |
473 | /* somebody has beaten us to it */ | |
474 | if (!IS_ERR(realfile)) | |
475 | fput(realfile); | |
476 | realfile = od->upperfile; | |
e9be9d5e | 477 | } |
3d268c9b | 478 | mutex_unlock(&inode->i_mutex); |
e9be9d5e | 479 | } |
e9be9d5e MS |
480 | } |
481 | ||
482 | return vfs_fsync_range(realfile, start, end, datasync); | |
483 | } | |
484 | ||
485 | static int ovl_dir_release(struct inode *inode, struct file *file) | |
486 | { | |
487 | struct ovl_dir_file *od = file->private_data; | |
488 | ||
489 | if (od->cache) { | |
490 | mutex_lock(&inode->i_mutex); | |
491 | ovl_cache_put(od, file->f_path.dentry); | |
492 | mutex_unlock(&inode->i_mutex); | |
493 | } | |
494 | fput(od->realfile); | |
495 | if (od->upperfile) | |
496 | fput(od->upperfile); | |
497 | kfree(od); | |
498 | ||
499 | return 0; | |
500 | } | |
501 | ||
502 | static int ovl_dir_open(struct inode *inode, struct file *file) | |
503 | { | |
504 | struct path realpath; | |
505 | struct file *realfile; | |
506 | struct ovl_dir_file *od; | |
507 | enum ovl_path_type type; | |
508 | ||
509 | od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); | |
510 | if (!od) | |
511 | return -ENOMEM; | |
512 | ||
513 | type = ovl_path_real(file->f_path.dentry, &realpath); | |
514 | realfile = ovl_path_open(&realpath, file->f_flags); | |
515 | if (IS_ERR(realfile)) { | |
516 | kfree(od); | |
517 | return PTR_ERR(realfile); | |
518 | } | |
519 | INIT_LIST_HEAD(&od->cursor.l_node); | |
520 | od->realfile = realfile; | |
521 | od->is_real = (type != OVL_PATH_MERGE); | |
522 | od->is_upper = (type != OVL_PATH_LOWER); | |
c2096537 | 523 | od->cursor.is_cursor = true; |
e9be9d5e MS |
524 | file->private_data = od; |
525 | ||
526 | return 0; | |
527 | } | |
528 | ||
529 | const struct file_operations ovl_dir_operations = { | |
530 | .read = generic_read_dir, | |
531 | .open = ovl_dir_open, | |
532 | .iterate = ovl_iterate, | |
533 | .llseek = ovl_dir_llseek, | |
534 | .fsync = ovl_dir_fsync, | |
535 | .release = ovl_dir_release, | |
536 | }; | |
537 | ||
538 | int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) | |
539 | { | |
540 | int err; | |
e9be9d5e MS |
541 | struct ovl_cache_entry *p; |
542 | ||
c9f00fdb | 543 | err = ovl_dir_read_merged(dentry, list); |
e9be9d5e MS |
544 | if (err) |
545 | return err; | |
546 | ||
547 | err = 0; | |
548 | ||
549 | list_for_each_entry(p, list, l_node) { | |
550 | if (p->is_whiteout) | |
551 | continue; | |
552 | ||
553 | if (p->name[0] == '.') { | |
554 | if (p->len == 1) | |
555 | continue; | |
556 | if (p->len == 2 && p->name[1] == '.') | |
557 | continue; | |
558 | } | |
559 | err = -ENOTEMPTY; | |
560 | break; | |
561 | } | |
562 | ||
563 | return err; | |
564 | } | |
565 | ||
566 | void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) | |
567 | { | |
568 | struct ovl_cache_entry *p; | |
569 | ||
d1b72cc6 | 570 | mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD); |
e9be9d5e MS |
571 | list_for_each_entry(p, list, l_node) { |
572 | struct dentry *dentry; | |
573 | ||
574 | if (!p->is_whiteout) | |
575 | continue; | |
576 | ||
577 | dentry = lookup_one_len(p->name, upper, p->len); | |
578 | if (IS_ERR(dentry)) { | |
579 | pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n", | |
580 | upper->d_name.name, p->len, p->name, | |
581 | (int) PTR_ERR(dentry)); | |
582 | continue; | |
583 | } | |
584 | ovl_cleanup(upper->d_inode, dentry); | |
585 | dput(dentry); | |
586 | } | |
587 | mutex_unlock(&upper->d_inode->i_mutex); | |
588 | } |