Commit | Line | Data |
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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/cred.h> | |
15 | #include "overlayfs.h" | |
16 | ||
17 | void ovl_cleanup(struct inode *wdir, struct dentry *wdentry) | |
18 | { | |
19 | int err; | |
20 | ||
21 | dget(wdentry); | |
22 | if (S_ISDIR(wdentry->d_inode->i_mode)) | |
23 | err = ovl_do_rmdir(wdir, wdentry); | |
24 | else | |
25 | err = ovl_do_unlink(wdir, wdentry); | |
26 | dput(wdentry); | |
27 | ||
28 | if (err) { | |
29 | pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n", | |
30 | wdentry, err); | |
31 | } | |
32 | } | |
33 | ||
34 | struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry) | |
35 | { | |
36 | struct dentry *temp; | |
37 | char name[20]; | |
38 | ||
39 | snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry); | |
40 | ||
41 | temp = lookup_one_len(name, workdir, strlen(name)); | |
42 | if (!IS_ERR(temp) && temp->d_inode) { | |
43 | pr_err("overlayfs: workdir/%s already exists\n", name); | |
44 | dput(temp); | |
45 | temp = ERR_PTR(-EIO); | |
46 | } | |
47 | ||
48 | return temp; | |
49 | } | |
50 | ||
51 | /* caller holds i_mutex on workdir */ | |
52 | static struct dentry *ovl_whiteout(struct dentry *workdir, | |
53 | struct dentry *dentry) | |
54 | { | |
55 | int err; | |
56 | struct dentry *whiteout; | |
57 | struct inode *wdir = workdir->d_inode; | |
58 | ||
59 | whiteout = ovl_lookup_temp(workdir, dentry); | |
60 | if (IS_ERR(whiteout)) | |
61 | return whiteout; | |
62 | ||
63 | err = ovl_do_whiteout(wdir, whiteout); | |
64 | if (err) { | |
65 | dput(whiteout); | |
66 | whiteout = ERR_PTR(err); | |
67 | } | |
68 | ||
69 | return whiteout; | |
70 | } | |
71 | ||
72 | int ovl_create_real(struct inode *dir, struct dentry *newdentry, | |
73 | struct kstat *stat, const char *link, | |
74 | struct dentry *hardlink, bool debug) | |
75 | { | |
76 | int err; | |
77 | ||
78 | if (newdentry->d_inode) | |
79 | return -ESTALE; | |
80 | ||
81 | if (hardlink) { | |
82 | err = ovl_do_link(hardlink, dir, newdentry, debug); | |
83 | } else { | |
84 | switch (stat->mode & S_IFMT) { | |
85 | case S_IFREG: | |
86 | err = ovl_do_create(dir, newdentry, stat->mode, debug); | |
87 | break; | |
88 | ||
89 | case S_IFDIR: | |
90 | err = ovl_do_mkdir(dir, newdentry, stat->mode, debug); | |
91 | break; | |
92 | ||
93 | case S_IFCHR: | |
94 | case S_IFBLK: | |
95 | case S_IFIFO: | |
96 | case S_IFSOCK: | |
97 | err = ovl_do_mknod(dir, newdentry, | |
98 | stat->mode, stat->rdev, debug); | |
99 | break; | |
100 | ||
101 | case S_IFLNK: | |
102 | err = ovl_do_symlink(dir, newdentry, link, debug); | |
103 | break; | |
104 | ||
105 | default: | |
106 | err = -EPERM; | |
107 | } | |
108 | } | |
109 | if (!err && WARN_ON(!newdentry->d_inode)) { | |
110 | /* | |
111 | * Not quite sure if non-instantiated dentry is legal or not. | |
112 | * VFS doesn't seem to care so check and warn here. | |
113 | */ | |
114 | err = -ENOENT; | |
115 | } | |
116 | return err; | |
117 | } | |
118 | ||
119 | static int ovl_set_opaque(struct dentry *upperdentry) | |
120 | { | |
121 | return ovl_do_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0); | |
122 | } | |
123 | ||
124 | static void ovl_remove_opaque(struct dentry *upperdentry) | |
125 | { | |
126 | int err; | |
127 | ||
128 | err = ovl_do_removexattr(upperdentry, ovl_opaque_xattr); | |
129 | if (err) { | |
130 | pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n", | |
131 | upperdentry->d_name.name, err); | |
132 | } | |
133 | } | |
134 | ||
135 | static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
136 | struct kstat *stat) | |
137 | { | |
138 | int err; | |
139 | enum ovl_path_type type; | |
140 | struct path realpath; | |
141 | ||
142 | type = ovl_path_real(dentry, &realpath); | |
143 | err = vfs_getattr(&realpath, stat); | |
144 | if (err) | |
145 | return err; | |
146 | ||
147 | stat->dev = dentry->d_sb->s_dev; | |
148 | stat->ino = dentry->d_inode->i_ino; | |
149 | ||
150 | /* | |
151 | * It's probably not worth it to count subdirs to get the | |
152 | * correct link count. nlink=1 seems to pacify 'find' and | |
153 | * other utilities. | |
154 | */ | |
155 | if (type == OVL_PATH_MERGE) | |
156 | stat->nlink = 1; | |
157 | ||
158 | return 0; | |
159 | } | |
160 | ||
161 | static int ovl_create_upper(struct dentry *dentry, struct inode *inode, | |
162 | struct kstat *stat, const char *link, | |
163 | struct dentry *hardlink) | |
164 | { | |
165 | struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); | |
166 | struct inode *udir = upperdir->d_inode; | |
167 | struct dentry *newdentry; | |
168 | int err; | |
169 | ||
170 | mutex_lock_nested(&udir->i_mutex, I_MUTEX_PARENT); | |
171 | newdentry = lookup_one_len(dentry->d_name.name, upperdir, | |
172 | dentry->d_name.len); | |
173 | err = PTR_ERR(newdentry); | |
174 | if (IS_ERR(newdentry)) | |
175 | goto out_unlock; | |
176 | err = ovl_create_real(udir, newdentry, stat, link, hardlink, false); | |
177 | if (err) | |
178 | goto out_dput; | |
179 | ||
180 | ovl_dentry_version_inc(dentry->d_parent); | |
181 | ovl_dentry_update(dentry, newdentry); | |
182 | ovl_copyattr(newdentry->d_inode, inode); | |
183 | d_instantiate(dentry, inode); | |
184 | newdentry = NULL; | |
185 | out_dput: | |
186 | dput(newdentry); | |
187 | out_unlock: | |
188 | mutex_unlock(&udir->i_mutex); | |
189 | return err; | |
190 | } | |
191 | ||
192 | static int ovl_lock_rename_workdir(struct dentry *workdir, | |
193 | struct dentry *upperdir) | |
194 | { | |
195 | /* Workdir should not be the same as upperdir */ | |
196 | if (workdir == upperdir) | |
197 | goto err; | |
198 | ||
199 | /* Workdir should not be subdir of upperdir and vice versa */ | |
200 | if (lock_rename(workdir, upperdir) != NULL) | |
201 | goto err_unlock; | |
202 | ||
203 | return 0; | |
204 | ||
205 | err_unlock: | |
206 | unlock_rename(workdir, upperdir); | |
207 | err: | |
208 | pr_err("overlayfs: failed to lock workdir+upperdir\n"); | |
209 | return -EIO; | |
210 | } | |
211 | ||
212 | static struct dentry *ovl_clear_empty(struct dentry *dentry, | |
213 | struct list_head *list) | |
214 | { | |
215 | struct dentry *workdir = ovl_workdir(dentry); | |
216 | struct inode *wdir = workdir->d_inode; | |
217 | struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); | |
218 | struct inode *udir = upperdir->d_inode; | |
219 | struct path upperpath; | |
220 | struct dentry *upper; | |
221 | struct dentry *opaquedir; | |
222 | struct kstat stat; | |
223 | int err; | |
224 | ||
225 | err = ovl_lock_rename_workdir(workdir, upperdir); | |
226 | if (err) | |
227 | goto out; | |
228 | ||
229 | ovl_path_upper(dentry, &upperpath); | |
230 | err = vfs_getattr(&upperpath, &stat); | |
231 | if (err) | |
232 | goto out_unlock; | |
233 | ||
234 | err = -ESTALE; | |
235 | if (!S_ISDIR(stat.mode)) | |
236 | goto out_unlock; | |
237 | upper = upperpath.dentry; | |
238 | if (upper->d_parent->d_inode != udir) | |
239 | goto out_unlock; | |
240 | ||
241 | opaquedir = ovl_lookup_temp(workdir, dentry); | |
242 | err = PTR_ERR(opaquedir); | |
243 | if (IS_ERR(opaquedir)) | |
244 | goto out_unlock; | |
245 | ||
246 | err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true); | |
247 | if (err) | |
248 | goto out_dput; | |
249 | ||
250 | err = ovl_copy_xattr(upper, opaquedir); | |
251 | if (err) | |
252 | goto out_cleanup; | |
253 | ||
254 | err = ovl_set_opaque(opaquedir); | |
255 | if (err) | |
256 | goto out_cleanup; | |
257 | ||
258 | mutex_lock(&opaquedir->d_inode->i_mutex); | |
259 | err = ovl_set_attr(opaquedir, &stat); | |
260 | mutex_unlock(&opaquedir->d_inode->i_mutex); | |
261 | if (err) | |
262 | goto out_cleanup; | |
263 | ||
264 | err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE); | |
265 | if (err) | |
266 | goto out_cleanup; | |
267 | ||
268 | ovl_cleanup_whiteouts(upper, list); | |
269 | ovl_cleanup(wdir, upper); | |
270 | unlock_rename(workdir, upperdir); | |
271 | ||
272 | /* dentry's upper doesn't match now, get rid of it */ | |
273 | d_drop(dentry); | |
274 | ||
275 | return opaquedir; | |
276 | ||
277 | out_cleanup: | |
278 | ovl_cleanup(wdir, opaquedir); | |
279 | out_dput: | |
280 | dput(opaquedir); | |
281 | out_unlock: | |
282 | unlock_rename(workdir, upperdir); | |
283 | out: | |
284 | return ERR_PTR(err); | |
285 | } | |
286 | ||
287 | static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry, | |
288 | enum ovl_path_type type) | |
289 | { | |
290 | int err; | |
291 | struct dentry *ret = NULL; | |
292 | LIST_HEAD(list); | |
293 | ||
294 | err = ovl_check_empty_dir(dentry, &list); | |
295 | if (err) | |
296 | ret = ERR_PTR(err); | |
297 | else if (type == OVL_PATH_MERGE) | |
298 | ret = ovl_clear_empty(dentry, &list); | |
299 | ||
300 | ovl_cache_free(&list); | |
301 | ||
302 | return ret; | |
303 | } | |
304 | ||
305 | static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, | |
306 | struct kstat *stat, const char *link, | |
307 | struct dentry *hardlink) | |
308 | { | |
309 | struct dentry *workdir = ovl_workdir(dentry); | |
310 | struct inode *wdir = workdir->d_inode; | |
311 | struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); | |
312 | struct inode *udir = upperdir->d_inode; | |
313 | struct dentry *upper; | |
314 | struct dentry *newdentry; | |
315 | int err; | |
316 | ||
317 | err = ovl_lock_rename_workdir(workdir, upperdir); | |
318 | if (err) | |
319 | goto out; | |
320 | ||
321 | newdentry = ovl_lookup_temp(workdir, dentry); | |
322 | err = PTR_ERR(newdentry); | |
323 | if (IS_ERR(newdentry)) | |
324 | goto out_unlock; | |
325 | ||
326 | upper = lookup_one_len(dentry->d_name.name, upperdir, | |
327 | dentry->d_name.len); | |
328 | err = PTR_ERR(upper); | |
329 | if (IS_ERR(upper)) | |
330 | goto out_dput; | |
331 | ||
332 | err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true); | |
333 | if (err) | |
334 | goto out_dput2; | |
335 | ||
336 | if (S_ISDIR(stat->mode)) { | |
337 | err = ovl_set_opaque(newdentry); | |
338 | if (err) | |
339 | goto out_cleanup; | |
340 | ||
341 | err = ovl_do_rename(wdir, newdentry, udir, upper, | |
342 | RENAME_EXCHANGE); | |
343 | if (err) | |
344 | goto out_cleanup; | |
345 | ||
346 | ovl_cleanup(wdir, upper); | |
347 | } else { | |
348 | err = ovl_do_rename(wdir, newdentry, udir, upper, 0); | |
349 | if (err) | |
350 | goto out_cleanup; | |
351 | } | |
352 | ovl_dentry_version_inc(dentry->d_parent); | |
353 | ovl_dentry_update(dentry, newdentry); | |
354 | ovl_copyattr(newdentry->d_inode, inode); | |
355 | d_instantiate(dentry, inode); | |
356 | newdentry = NULL; | |
357 | out_dput2: | |
358 | dput(upper); | |
359 | out_dput: | |
360 | dput(newdentry); | |
361 | out_unlock: | |
362 | unlock_rename(workdir, upperdir); | |
363 | out: | |
364 | return err; | |
365 | ||
366 | out_cleanup: | |
367 | ovl_cleanup(wdir, newdentry); | |
368 | goto out_dput2; | |
369 | } | |
370 | ||
371 | static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev, | |
372 | const char *link, struct dentry *hardlink) | |
373 | { | |
374 | int err; | |
375 | struct inode *inode; | |
376 | struct kstat stat = { | |
377 | .mode = mode, | |
378 | .rdev = rdev, | |
379 | }; | |
380 | ||
381 | err = -ENOMEM; | |
382 | inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata); | |
383 | if (!inode) | |
384 | goto out; | |
385 | ||
386 | err = ovl_copy_up(dentry->d_parent); | |
387 | if (err) | |
388 | goto out_iput; | |
389 | ||
390 | if (!ovl_dentry_is_opaque(dentry)) { | |
391 | err = ovl_create_upper(dentry, inode, &stat, link, hardlink); | |
392 | } else { | |
393 | const struct cred *old_cred; | |
394 | struct cred *override_cred; | |
395 | ||
396 | err = -ENOMEM; | |
397 | override_cred = prepare_creds(); | |
398 | if (!override_cred) | |
399 | goto out_iput; | |
400 | ||
401 | /* | |
402 | * CAP_SYS_ADMIN for setting opaque xattr | |
403 | * CAP_DAC_OVERRIDE for create in workdir, rename | |
404 | * CAP_FOWNER for removing whiteout from sticky dir | |
405 | */ | |
406 | cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
407 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
408 | cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
409 | old_cred = override_creds(override_cred); | |
410 | ||
411 | err = ovl_create_over_whiteout(dentry, inode, &stat, link, | |
412 | hardlink); | |
413 | ||
414 | revert_creds(old_cred); | |
415 | put_cred(override_cred); | |
416 | } | |
417 | ||
418 | if (!err) | |
419 | inode = NULL; | |
420 | out_iput: | |
421 | iput(inode); | |
422 | out: | |
423 | return err; | |
424 | } | |
425 | ||
426 | static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev, | |
427 | const char *link) | |
428 | { | |
429 | int err; | |
430 | ||
431 | err = ovl_want_write(dentry); | |
432 | if (!err) { | |
433 | err = ovl_create_or_link(dentry, mode, rdev, link, NULL); | |
434 | ovl_drop_write(dentry); | |
435 | } | |
436 | ||
437 | return err; | |
438 | } | |
439 | ||
440 | static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
441 | bool excl) | |
442 | { | |
443 | return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL); | |
444 | } | |
445 | ||
446 | static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
447 | { | |
448 | return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL); | |
449 | } | |
450 | ||
451 | static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, | |
452 | dev_t rdev) | |
453 | { | |
454 | /* Don't allow creation of "whiteout" on overlay */ | |
455 | if (S_ISCHR(mode) && rdev == WHITEOUT_DEV) | |
456 | return -EPERM; | |
457 | ||
458 | return ovl_create_object(dentry, mode, rdev, NULL); | |
459 | } | |
460 | ||
461 | static int ovl_symlink(struct inode *dir, struct dentry *dentry, | |
462 | const char *link) | |
463 | { | |
464 | return ovl_create_object(dentry, S_IFLNK, 0, link); | |
465 | } | |
466 | ||
467 | static int ovl_link(struct dentry *old, struct inode *newdir, | |
468 | struct dentry *new) | |
469 | { | |
470 | int err; | |
471 | struct dentry *upper; | |
472 | ||
473 | err = ovl_want_write(old); | |
474 | if (err) | |
475 | goto out; | |
476 | ||
477 | err = ovl_copy_up(old); | |
478 | if (err) | |
479 | goto out_drop_write; | |
480 | ||
481 | upper = ovl_dentry_upper(old); | |
482 | err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper); | |
483 | ||
484 | out_drop_write: | |
485 | ovl_drop_write(old); | |
486 | out: | |
487 | return err; | |
488 | } | |
489 | ||
490 | static int ovl_remove_and_whiteout(struct dentry *dentry, | |
491 | enum ovl_path_type type, bool is_dir) | |
492 | { | |
493 | struct dentry *workdir = ovl_workdir(dentry); | |
494 | struct inode *wdir = workdir->d_inode; | |
495 | struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); | |
496 | struct inode *udir = upperdir->d_inode; | |
497 | struct dentry *whiteout; | |
498 | struct dentry *upper; | |
499 | struct dentry *opaquedir = NULL; | |
500 | int err; | |
501 | ||
502 | if (is_dir) { | |
503 | opaquedir = ovl_check_empty_and_clear(dentry, type); | |
504 | err = PTR_ERR(opaquedir); | |
505 | if (IS_ERR(opaquedir)) | |
506 | goto out; | |
507 | } | |
508 | ||
509 | err = ovl_lock_rename_workdir(workdir, upperdir); | |
510 | if (err) | |
511 | goto out_dput; | |
512 | ||
513 | whiteout = ovl_whiteout(workdir, dentry); | |
514 | err = PTR_ERR(whiteout); | |
515 | if (IS_ERR(whiteout)) | |
516 | goto out_unlock; | |
517 | ||
518 | if (type == OVL_PATH_LOWER) { | |
519 | upper = lookup_one_len(dentry->d_name.name, upperdir, | |
520 | dentry->d_name.len); | |
521 | err = PTR_ERR(upper); | |
522 | if (IS_ERR(upper)) | |
523 | goto kill_whiteout; | |
524 | ||
525 | err = ovl_do_rename(wdir, whiteout, udir, upper, 0); | |
526 | dput(upper); | |
527 | if (err) | |
528 | goto kill_whiteout; | |
529 | } else { | |
530 | int flags = 0; | |
531 | ||
532 | upper = ovl_dentry_upper(dentry); | |
533 | if (opaquedir) | |
534 | upper = opaquedir; | |
535 | err = -ESTALE; | |
536 | if (upper->d_parent != upperdir) | |
537 | goto kill_whiteout; | |
538 | ||
539 | if (is_dir) | |
540 | flags |= RENAME_EXCHANGE; | |
541 | ||
542 | err = ovl_do_rename(wdir, whiteout, udir, upper, flags); | |
543 | if (err) | |
544 | goto kill_whiteout; | |
545 | ||
546 | if (is_dir) | |
547 | ovl_cleanup(wdir, upper); | |
548 | } | |
549 | ovl_dentry_version_inc(dentry->d_parent); | |
550 | out_d_drop: | |
551 | d_drop(dentry); | |
552 | dput(whiteout); | |
553 | out_unlock: | |
554 | unlock_rename(workdir, upperdir); | |
555 | out_dput: | |
556 | dput(opaquedir); | |
557 | out: | |
558 | return err; | |
559 | ||
560 | kill_whiteout: | |
561 | ovl_cleanup(wdir, whiteout); | |
562 | goto out_d_drop; | |
563 | } | |
564 | ||
565 | static int ovl_remove_upper(struct dentry *dentry, bool is_dir) | |
566 | { | |
567 | struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent); | |
568 | struct inode *dir = upperdir->d_inode; | |
569 | struct dentry *upper = ovl_dentry_upper(dentry); | |
570 | int err; | |
571 | ||
572 | mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT); | |
573 | err = -ESTALE; | |
574 | if (upper->d_parent == upperdir) { | |
575 | /* Don't let d_delete() think it can reset d_inode */ | |
576 | dget(upper); | |
577 | if (is_dir) | |
578 | err = vfs_rmdir(dir, upper); | |
579 | else | |
580 | err = vfs_unlink(dir, upper, NULL); | |
581 | dput(upper); | |
582 | ovl_dentry_version_inc(dentry->d_parent); | |
583 | } | |
584 | ||
585 | /* | |
586 | * Keeping this dentry hashed would mean having to release | |
587 | * upperpath/lowerpath, which could only be done if we are the | |
588 | * sole user of this dentry. Too tricky... Just unhash for | |
589 | * now. | |
590 | */ | |
591 | d_drop(dentry); | |
592 | mutex_unlock(&dir->i_mutex); | |
593 | ||
594 | return err; | |
595 | } | |
596 | ||
597 | static inline int ovl_check_sticky(struct dentry *dentry) | |
598 | { | |
599 | struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode; | |
600 | struct inode *inode = ovl_dentry_real(dentry)->d_inode; | |
601 | ||
602 | if (check_sticky(dir, inode)) | |
603 | return -EPERM; | |
604 | ||
605 | return 0; | |
606 | } | |
607 | ||
608 | static int ovl_do_remove(struct dentry *dentry, bool is_dir) | |
609 | { | |
610 | enum ovl_path_type type; | |
611 | int err; | |
612 | ||
613 | err = ovl_check_sticky(dentry); | |
614 | if (err) | |
615 | goto out; | |
616 | ||
617 | err = ovl_want_write(dentry); | |
618 | if (err) | |
619 | goto out; | |
620 | ||
621 | err = ovl_copy_up(dentry->d_parent); | |
622 | if (err) | |
623 | goto out_drop_write; | |
624 | ||
625 | type = ovl_path_type(dentry); | |
626 | if (type == OVL_PATH_PURE_UPPER) { | |
627 | err = ovl_remove_upper(dentry, is_dir); | |
628 | } else { | |
629 | const struct cred *old_cred; | |
630 | struct cred *override_cred; | |
631 | ||
632 | err = -ENOMEM; | |
633 | override_cred = prepare_creds(); | |
634 | if (!override_cred) | |
635 | goto out_drop_write; | |
636 | ||
637 | /* | |
638 | * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir | |
639 | * CAP_DAC_OVERRIDE for create in workdir, rename | |
640 | * CAP_FOWNER for removing whiteout from sticky dir | |
641 | * CAP_FSETID for chmod of opaque dir | |
642 | * CAP_CHOWN for chown of opaque dir | |
643 | */ | |
644 | cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
645 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
646 | cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
647 | cap_raise(override_cred->cap_effective, CAP_FSETID); | |
648 | cap_raise(override_cred->cap_effective, CAP_CHOWN); | |
649 | old_cred = override_creds(override_cred); | |
650 | ||
651 | err = ovl_remove_and_whiteout(dentry, type, is_dir); | |
652 | ||
653 | revert_creds(old_cred); | |
654 | put_cred(override_cred); | |
655 | } | |
656 | out_drop_write: | |
657 | ovl_drop_write(dentry); | |
658 | out: | |
659 | return err; | |
660 | } | |
661 | ||
662 | static int ovl_unlink(struct inode *dir, struct dentry *dentry) | |
663 | { | |
664 | return ovl_do_remove(dentry, false); | |
665 | } | |
666 | ||
667 | static int ovl_rmdir(struct inode *dir, struct dentry *dentry) | |
668 | { | |
669 | return ovl_do_remove(dentry, true); | |
670 | } | |
671 | ||
672 | static int ovl_rename2(struct inode *olddir, struct dentry *old, | |
673 | struct inode *newdir, struct dentry *new, | |
674 | unsigned int flags) | |
675 | { | |
676 | int err; | |
677 | enum ovl_path_type old_type; | |
678 | enum ovl_path_type new_type; | |
679 | struct dentry *old_upperdir; | |
680 | struct dentry *new_upperdir; | |
681 | struct dentry *olddentry; | |
682 | struct dentry *newdentry; | |
683 | struct dentry *trap; | |
684 | bool old_opaque; | |
685 | bool new_opaque; | |
686 | bool new_create = false; | |
687 | bool cleanup_whiteout = false; | |
688 | bool overwrite = !(flags & RENAME_EXCHANGE); | |
689 | bool is_dir = S_ISDIR(old->d_inode->i_mode); | |
690 | bool new_is_dir = false; | |
691 | struct dentry *opaquedir = NULL; | |
692 | const struct cred *old_cred = NULL; | |
693 | struct cred *override_cred = NULL; | |
694 | ||
695 | err = -EINVAL; | |
696 | if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE)) | |
697 | goto out; | |
698 | ||
699 | flags &= ~RENAME_NOREPLACE; | |
700 | ||
701 | err = ovl_check_sticky(old); | |
702 | if (err) | |
703 | goto out; | |
704 | ||
705 | /* Don't copy up directory trees */ | |
706 | old_type = ovl_path_type(old); | |
707 | err = -EXDEV; | |
708 | if ((old_type == OVL_PATH_LOWER || old_type == OVL_PATH_MERGE) && is_dir) | |
709 | goto out; | |
710 | ||
711 | if (new->d_inode) { | |
712 | err = ovl_check_sticky(new); | |
713 | if (err) | |
714 | goto out; | |
715 | ||
716 | if (S_ISDIR(new->d_inode->i_mode)) | |
717 | new_is_dir = true; | |
718 | ||
719 | new_type = ovl_path_type(new); | |
720 | err = -EXDEV; | |
721 | if (!overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) | |
722 | goto out; | |
723 | ||
724 | err = 0; | |
725 | if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) { | |
726 | if (ovl_dentry_lower(old)->d_inode == | |
727 | ovl_dentry_lower(new)->d_inode) | |
728 | goto out; | |
729 | } | |
730 | if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) { | |
731 | if (ovl_dentry_upper(old)->d_inode == | |
732 | ovl_dentry_upper(new)->d_inode) | |
733 | goto out; | |
734 | } | |
735 | } else { | |
736 | if (ovl_dentry_is_opaque(new)) | |
737 | new_type = OVL_PATH_UPPER; | |
738 | else | |
739 | new_type = OVL_PATH_PURE_UPPER; | |
740 | } | |
741 | ||
742 | err = ovl_want_write(old); | |
743 | if (err) | |
744 | goto out; | |
745 | ||
746 | err = ovl_copy_up(old); | |
747 | if (err) | |
748 | goto out_drop_write; | |
749 | ||
750 | err = ovl_copy_up(new->d_parent); | |
751 | if (err) | |
752 | goto out_drop_write; | |
753 | if (!overwrite) { | |
754 | err = ovl_copy_up(new); | |
755 | if (err) | |
756 | goto out_drop_write; | |
757 | } | |
758 | ||
759 | old_opaque = old_type != OVL_PATH_PURE_UPPER; | |
760 | new_opaque = new_type != OVL_PATH_PURE_UPPER; | |
761 | ||
762 | if (old_opaque || new_opaque) { | |
763 | err = -ENOMEM; | |
764 | override_cred = prepare_creds(); | |
765 | if (!override_cred) | |
766 | goto out_drop_write; | |
767 | ||
768 | /* | |
769 | * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir | |
770 | * CAP_DAC_OVERRIDE for create in workdir | |
771 | * CAP_FOWNER for removing whiteout from sticky dir | |
772 | * CAP_FSETID for chmod of opaque dir | |
773 | * CAP_CHOWN for chown of opaque dir | |
774 | */ | |
775 | cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN); | |
776 | cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); | |
777 | cap_raise(override_cred->cap_effective, CAP_FOWNER); | |
778 | cap_raise(override_cred->cap_effective, CAP_FSETID); | |
779 | cap_raise(override_cred->cap_effective, CAP_CHOWN); | |
780 | old_cred = override_creds(override_cred); | |
781 | } | |
782 | ||
783 | if (overwrite && (new_type == OVL_PATH_LOWER || new_type == OVL_PATH_MERGE) && new_is_dir) { | |
784 | opaquedir = ovl_check_empty_and_clear(new, new_type); | |
785 | err = PTR_ERR(opaquedir); | |
786 | if (IS_ERR(opaquedir)) { | |
787 | opaquedir = NULL; | |
788 | goto out_revert_creds; | |
789 | } | |
790 | } | |
791 | ||
792 | if (overwrite) { | |
793 | if (old_opaque) { | |
794 | if (new->d_inode || !new_opaque) { | |
795 | /* Whiteout source */ | |
796 | flags |= RENAME_WHITEOUT; | |
797 | } else { | |
798 | /* Switch whiteouts */ | |
799 | flags |= RENAME_EXCHANGE; | |
800 | } | |
801 | } else if (is_dir && !new->d_inode && new_opaque) { | |
802 | flags |= RENAME_EXCHANGE; | |
803 | cleanup_whiteout = true; | |
804 | } | |
805 | } | |
806 | ||
807 | old_upperdir = ovl_dentry_upper(old->d_parent); | |
808 | new_upperdir = ovl_dentry_upper(new->d_parent); | |
809 | ||
810 | trap = lock_rename(new_upperdir, old_upperdir); | |
811 | ||
812 | olddentry = ovl_dentry_upper(old); | |
813 | newdentry = ovl_dentry_upper(new); | |
814 | if (newdentry) { | |
815 | if (opaquedir) { | |
816 | newdentry = opaquedir; | |
817 | opaquedir = NULL; | |
818 | } else { | |
819 | dget(newdentry); | |
820 | } | |
821 | } else { | |
822 | new_create = true; | |
823 | newdentry = lookup_one_len(new->d_name.name, new_upperdir, | |
824 | new->d_name.len); | |
825 | err = PTR_ERR(newdentry); | |
826 | if (IS_ERR(newdentry)) | |
827 | goto out_unlock; | |
828 | } | |
829 | ||
830 | err = -ESTALE; | |
831 | if (olddentry->d_parent != old_upperdir) | |
832 | goto out_dput; | |
833 | if (newdentry->d_parent != new_upperdir) | |
834 | goto out_dput; | |
835 | if (olddentry == trap) | |
836 | goto out_dput; | |
837 | if (newdentry == trap) | |
838 | goto out_dput; | |
839 | ||
840 | if (is_dir && !old_opaque && new_opaque) { | |
841 | err = ovl_set_opaque(olddentry); | |
842 | if (err) | |
843 | goto out_dput; | |
844 | } | |
845 | if (!overwrite && new_is_dir && old_opaque && !new_opaque) { | |
846 | err = ovl_set_opaque(newdentry); | |
847 | if (err) | |
848 | goto out_dput; | |
849 | } | |
850 | ||
851 | if (old_opaque || new_opaque) { | |
852 | err = ovl_do_rename(old_upperdir->d_inode, olddentry, | |
853 | new_upperdir->d_inode, newdentry, | |
854 | flags); | |
855 | } else { | |
856 | /* No debug for the plain case */ | |
857 | BUG_ON(flags & ~RENAME_EXCHANGE); | |
858 | err = vfs_rename(old_upperdir->d_inode, olddentry, | |
859 | new_upperdir->d_inode, newdentry, | |
860 | NULL, flags); | |
861 | } | |
862 | ||
863 | if (err) { | |
864 | if (is_dir && !old_opaque && new_opaque) | |
865 | ovl_remove_opaque(olddentry); | |
866 | if (!overwrite && new_is_dir && old_opaque && !new_opaque) | |
867 | ovl_remove_opaque(newdentry); | |
868 | goto out_dput; | |
869 | } | |
870 | ||
871 | if (is_dir && old_opaque && !new_opaque) | |
872 | ovl_remove_opaque(olddentry); | |
873 | if (!overwrite && new_is_dir && !old_opaque && new_opaque) | |
874 | ovl_remove_opaque(newdentry); | |
875 | ||
876 | if (old_opaque != new_opaque) { | |
877 | ovl_dentry_set_opaque(old, new_opaque); | |
878 | if (!overwrite) | |
879 | ovl_dentry_set_opaque(new, old_opaque); | |
880 | } | |
881 | ||
882 | if (cleanup_whiteout) | |
883 | ovl_cleanup(old_upperdir->d_inode, newdentry); | |
884 | ||
885 | ovl_dentry_version_inc(old->d_parent); | |
886 | ovl_dentry_version_inc(new->d_parent); | |
887 | ||
888 | out_dput: | |
889 | dput(newdentry); | |
890 | out_unlock: | |
891 | unlock_rename(new_upperdir, old_upperdir); | |
892 | out_revert_creds: | |
893 | if (old_opaque || new_opaque) { | |
894 | revert_creds(old_cred); | |
895 | put_cred(override_cred); | |
896 | } | |
897 | out_drop_write: | |
898 | ovl_drop_write(old); | |
899 | out: | |
900 | dput(opaquedir); | |
901 | return err; | |
902 | } | |
903 | ||
904 | const struct inode_operations ovl_dir_inode_operations = { | |
905 | .lookup = ovl_lookup, | |
906 | .mkdir = ovl_mkdir, | |
907 | .symlink = ovl_symlink, | |
908 | .unlink = ovl_unlink, | |
909 | .rmdir = ovl_rmdir, | |
910 | .rename2 = ovl_rename2, | |
911 | .link = ovl_link, | |
912 | .setattr = ovl_setattr, | |
913 | .create = ovl_create, | |
914 | .mknod = ovl_mknod, | |
915 | .permission = ovl_permission, | |
916 | .getattr = ovl_dir_getattr, | |
917 | .setxattr = ovl_setxattr, | |
918 | .getxattr = ovl_getxattr, | |
919 | .listxattr = ovl_listxattr, | |
920 | .removexattr = ovl_removexattr, | |
921 | }; |