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Merge branch 'mailbox-for-next' of git://git.linaro.org/landing-teams/working/fujitsu...
[karo-tx-linux.git] / fs / overlayfs / dir.c
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 (d_is_dir(wdentry))
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_XATTR_OPAQUE, "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_XATTR_OPAQUE);
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 (OVL_TYPE_MERGE(type))
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         if (WARN_ON(!workdir))
226                 return ERR_PTR(-EROFS);
227
228         err = ovl_lock_rename_workdir(workdir, upperdir);
229         if (err)
230                 goto out;
231
232         ovl_path_upper(dentry, &upperpath);
233         err = vfs_getattr(&upperpath, &stat);
234         if (err)
235                 goto out_unlock;
236
237         err = -ESTALE;
238         if (!S_ISDIR(stat.mode))
239                 goto out_unlock;
240         upper = upperpath.dentry;
241         if (upper->d_parent->d_inode != udir)
242                 goto out_unlock;
243
244         opaquedir = ovl_lookup_temp(workdir, dentry);
245         err = PTR_ERR(opaquedir);
246         if (IS_ERR(opaquedir))
247                 goto out_unlock;
248
249         err = ovl_create_real(wdir, opaquedir, &stat, NULL, NULL, true);
250         if (err)
251                 goto out_dput;
252
253         err = ovl_copy_xattr(upper, opaquedir);
254         if (err)
255                 goto out_cleanup;
256
257         err = ovl_set_opaque(opaquedir);
258         if (err)
259                 goto out_cleanup;
260
261         mutex_lock(&opaquedir->d_inode->i_mutex);
262         err = ovl_set_attr(opaquedir, &stat);
263         mutex_unlock(&opaquedir->d_inode->i_mutex);
264         if (err)
265                 goto out_cleanup;
266
267         err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
268         if (err)
269                 goto out_cleanup;
270
271         ovl_cleanup_whiteouts(upper, list);
272         ovl_cleanup(wdir, upper);
273         unlock_rename(workdir, upperdir);
274
275         /* dentry's upper doesn't match now, get rid of it */
276         d_drop(dentry);
277
278         return opaquedir;
279
280 out_cleanup:
281         ovl_cleanup(wdir, opaquedir);
282 out_dput:
283         dput(opaquedir);
284 out_unlock:
285         unlock_rename(workdir, upperdir);
286 out:
287         return ERR_PTR(err);
288 }
289
290 static struct dentry *ovl_check_empty_and_clear(struct dentry *dentry)
291 {
292         int err;
293         struct dentry *ret = NULL;
294         LIST_HEAD(list);
295
296         err = ovl_check_empty_dir(dentry, &list);
297         if (err)
298                 ret = ERR_PTR(err);
299         else {
300                 /*
301                  * If no upperdentry then skip clearing whiteouts.
302                  *
303                  * Can race with copy-up, since we don't hold the upperdir
304                  * mutex.  Doesn't matter, since copy-up can't create a
305                  * non-empty directory from an empty one.
306                  */
307                 if (ovl_dentry_upper(dentry))
308                         ret = ovl_clear_empty(dentry, &list);
309         }
310
311         ovl_cache_free(&list);
312
313         return ret;
314 }
315
316 static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
317                                     struct kstat *stat, const char *link,
318                                     struct dentry *hardlink)
319 {
320         struct dentry *workdir = ovl_workdir(dentry);
321         struct inode *wdir = workdir->d_inode;
322         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
323         struct inode *udir = upperdir->d_inode;
324         struct dentry *upper;
325         struct dentry *newdentry;
326         int err;
327
328         if (WARN_ON(!workdir))
329                 return -EROFS;
330
331         err = ovl_lock_rename_workdir(workdir, upperdir);
332         if (err)
333                 goto out;
334
335         newdentry = ovl_lookup_temp(workdir, dentry);
336         err = PTR_ERR(newdentry);
337         if (IS_ERR(newdentry))
338                 goto out_unlock;
339
340         upper = lookup_one_len(dentry->d_name.name, upperdir,
341                                dentry->d_name.len);
342         err = PTR_ERR(upper);
343         if (IS_ERR(upper))
344                 goto out_dput;
345
346         err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
347         if (err)
348                 goto out_dput2;
349
350         if (S_ISDIR(stat->mode)) {
351                 err = ovl_set_opaque(newdentry);
352                 if (err)
353                         goto out_cleanup;
354
355                 err = ovl_do_rename(wdir, newdentry, udir, upper,
356                                     RENAME_EXCHANGE);
357                 if (err)
358                         goto out_cleanup;
359
360                 ovl_cleanup(wdir, upper);
361         } else {
362                 err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
363                 if (err)
364                         goto out_cleanup;
365         }
366         ovl_dentry_version_inc(dentry->d_parent);
367         ovl_dentry_update(dentry, newdentry);
368         ovl_copyattr(newdentry->d_inode, inode);
369         d_instantiate(dentry, inode);
370         newdentry = NULL;
371 out_dput2:
372         dput(upper);
373 out_dput:
374         dput(newdentry);
375 out_unlock:
376         unlock_rename(workdir, upperdir);
377 out:
378         return err;
379
380 out_cleanup:
381         ovl_cleanup(wdir, newdentry);
382         goto out_dput2;
383 }
384
385 static int ovl_create_or_link(struct dentry *dentry, int mode, dev_t rdev,
386                               const char *link, struct dentry *hardlink)
387 {
388         int err;
389         struct inode *inode;
390         struct kstat stat = {
391                 .mode = mode,
392                 .rdev = rdev,
393         };
394
395         err = -ENOMEM;
396         inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
397         if (!inode)
398                 goto out;
399
400         err = ovl_copy_up(dentry->d_parent);
401         if (err)
402                 goto out_iput;
403
404         if (!ovl_dentry_is_opaque(dentry)) {
405                 err = ovl_create_upper(dentry, inode, &stat, link, hardlink);
406         } else {
407                 const struct cred *old_cred;
408                 struct cred *override_cred;
409
410                 err = -ENOMEM;
411                 override_cred = prepare_creds();
412                 if (!override_cred)
413                         goto out_iput;
414
415                 /*
416                  * CAP_SYS_ADMIN for setting opaque xattr
417                  * CAP_DAC_OVERRIDE for create in workdir, rename
418                  * CAP_FOWNER for removing whiteout from sticky dir
419                  */
420                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
421                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
422                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
423                 old_cred = override_creds(override_cred);
424
425                 err = ovl_create_over_whiteout(dentry, inode, &stat, link,
426                                                hardlink);
427
428                 revert_creds(old_cred);
429                 put_cred(override_cred);
430         }
431
432         if (!err)
433                 inode = NULL;
434 out_iput:
435         iput(inode);
436 out:
437         return err;
438 }
439
440 static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
441                              const char *link)
442 {
443         int err;
444
445         err = ovl_want_write(dentry);
446         if (!err) {
447                 err = ovl_create_or_link(dentry, mode, rdev, link, NULL);
448                 ovl_drop_write(dentry);
449         }
450
451         return err;
452 }
453
454 static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
455                       bool excl)
456 {
457         return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
458 }
459
460 static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
461 {
462         return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
463 }
464
465 static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
466                      dev_t rdev)
467 {
468         /* Don't allow creation of "whiteout" on overlay */
469         if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
470                 return -EPERM;
471
472         return ovl_create_object(dentry, mode, rdev, NULL);
473 }
474
475 static int ovl_symlink(struct inode *dir, struct dentry *dentry,
476                        const char *link)
477 {
478         return ovl_create_object(dentry, S_IFLNK, 0, link);
479 }
480
481 static int ovl_link(struct dentry *old, struct inode *newdir,
482                     struct dentry *new)
483 {
484         int err;
485         struct dentry *upper;
486
487         err = ovl_want_write(old);
488         if (err)
489                 goto out;
490
491         err = ovl_copy_up(old);
492         if (err)
493                 goto out_drop_write;
494
495         upper = ovl_dentry_upper(old);
496         err = ovl_create_or_link(new, upper->d_inode->i_mode, 0, NULL, upper);
497
498 out_drop_write:
499         ovl_drop_write(old);
500 out:
501         return err;
502 }
503
504 static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
505 {
506         struct dentry *workdir = ovl_workdir(dentry);
507         struct inode *wdir = workdir->d_inode;
508         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
509         struct inode *udir = upperdir->d_inode;
510         struct dentry *whiteout;
511         struct dentry *upper;
512         struct dentry *opaquedir = NULL;
513         int err;
514
515         if (WARN_ON(!workdir))
516                 return -EROFS;
517
518         if (is_dir) {
519                 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) {
520                         opaquedir = ovl_check_empty_and_clear(dentry);
521                         err = PTR_ERR(opaquedir);
522                         if (IS_ERR(opaquedir))
523                                 goto out;
524                 } else {
525                         LIST_HEAD(list);
526
527                         /*
528                          * When removing an empty opaque directory, then it
529                          * makes no sense to replace it with an exact replica of
530                          * itself.  But emptiness still needs to be checked.
531                          */
532                         err = ovl_check_empty_dir(dentry, &list);
533                         ovl_cache_free(&list);
534                         if (err)
535                                 goto out;
536                 }
537         }
538
539         err = ovl_lock_rename_workdir(workdir, upperdir);
540         if (err)
541                 goto out_dput;
542
543         whiteout = ovl_whiteout(workdir, dentry);
544         err = PTR_ERR(whiteout);
545         if (IS_ERR(whiteout))
546                 goto out_unlock;
547
548         upper = ovl_dentry_upper(dentry);
549         if (!upper) {
550                 upper = lookup_one_len(dentry->d_name.name, upperdir,
551                                        dentry->d_name.len);
552                 err = PTR_ERR(upper);
553                 if (IS_ERR(upper))
554                         goto kill_whiteout;
555
556                 err = ovl_do_rename(wdir, whiteout, udir, upper, 0);
557                 dput(upper);
558                 if (err)
559                         goto kill_whiteout;
560         } else {
561                 int flags = 0;
562
563                 if (opaquedir)
564                         upper = opaquedir;
565                 err = -ESTALE;
566                 if (upper->d_parent != upperdir)
567                         goto kill_whiteout;
568
569                 if (is_dir)
570                         flags |= RENAME_EXCHANGE;
571
572                 err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
573                 if (err)
574                         goto kill_whiteout;
575
576                 if (is_dir)
577                         ovl_cleanup(wdir, upper);
578         }
579         ovl_dentry_version_inc(dentry->d_parent);
580 out_d_drop:
581         d_drop(dentry);
582         dput(whiteout);
583 out_unlock:
584         unlock_rename(workdir, upperdir);
585 out_dput:
586         dput(opaquedir);
587 out:
588         return err;
589
590 kill_whiteout:
591         ovl_cleanup(wdir, whiteout);
592         goto out_d_drop;
593 }
594
595 static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
596 {
597         struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
598         struct inode *dir = upperdir->d_inode;
599         struct dentry *upper = ovl_dentry_upper(dentry);
600         int err;
601
602         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
603         err = -ESTALE;
604         if (upper->d_parent == upperdir) {
605                 /* Don't let d_delete() think it can reset d_inode */
606                 dget(upper);
607                 if (is_dir)
608                         err = vfs_rmdir(dir, upper);
609                 else
610                         err = vfs_unlink(dir, upper, NULL);
611                 dput(upper);
612                 ovl_dentry_version_inc(dentry->d_parent);
613         }
614
615         /*
616          * Keeping this dentry hashed would mean having to release
617          * upperpath/lowerpath, which could only be done if we are the
618          * sole user of this dentry.  Too tricky...  Just unhash for
619          * now.
620          */
621         d_drop(dentry);
622         mutex_unlock(&dir->i_mutex);
623
624         return err;
625 }
626
627 static inline int ovl_check_sticky(struct dentry *dentry)
628 {
629         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
630         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
631
632         if (check_sticky(dir, inode))
633                 return -EPERM;
634
635         return 0;
636 }
637
638 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
639 {
640         enum ovl_path_type type;
641         int err;
642
643         err = ovl_check_sticky(dentry);
644         if (err)
645                 goto out;
646
647         err = ovl_want_write(dentry);
648         if (err)
649                 goto out;
650
651         err = ovl_copy_up(dentry->d_parent);
652         if (err)
653                 goto out_drop_write;
654
655         type = ovl_path_type(dentry);
656         if (OVL_TYPE_PURE_UPPER(type)) {
657                 err = ovl_remove_upper(dentry, is_dir);
658         } else {
659                 const struct cred *old_cred;
660                 struct cred *override_cred;
661
662                 err = -ENOMEM;
663                 override_cred = prepare_creds();
664                 if (!override_cred)
665                         goto out_drop_write;
666
667                 /*
668                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
669                  * CAP_DAC_OVERRIDE for create in workdir, rename
670                  * CAP_FOWNER for removing whiteout from sticky dir
671                  * CAP_FSETID for chmod of opaque dir
672                  * CAP_CHOWN for chown of opaque dir
673                  */
674                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
675                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
676                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
677                 cap_raise(override_cred->cap_effective, CAP_FSETID);
678                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
679                 old_cred = override_creds(override_cred);
680
681                 err = ovl_remove_and_whiteout(dentry, is_dir);
682
683                 revert_creds(old_cred);
684                 put_cred(override_cred);
685         }
686 out_drop_write:
687         ovl_drop_write(dentry);
688 out:
689         return err;
690 }
691
692 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
693 {
694         return ovl_do_remove(dentry, false);
695 }
696
697 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
698 {
699         return ovl_do_remove(dentry, true);
700 }
701
702 static int ovl_rename2(struct inode *olddir, struct dentry *old,
703                        struct inode *newdir, struct dentry *new,
704                        unsigned int flags)
705 {
706         int err;
707         enum ovl_path_type old_type;
708         enum ovl_path_type new_type;
709         struct dentry *old_upperdir;
710         struct dentry *new_upperdir;
711         struct dentry *olddentry;
712         struct dentry *newdentry;
713         struct dentry *trap;
714         bool old_opaque;
715         bool new_opaque;
716         bool new_create = false;
717         bool cleanup_whiteout = false;
718         bool overwrite = !(flags & RENAME_EXCHANGE);
719         bool is_dir = d_is_dir(old);
720         bool new_is_dir = false;
721         struct dentry *opaquedir = NULL;
722         const struct cred *old_cred = NULL;
723         struct cred *override_cred = NULL;
724
725         err = -EINVAL;
726         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
727                 goto out;
728
729         flags &= ~RENAME_NOREPLACE;
730
731         err = ovl_check_sticky(old);
732         if (err)
733                 goto out;
734
735         /* Don't copy up directory trees */
736         old_type = ovl_path_type(old);
737         err = -EXDEV;
738         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
739                 goto out;
740
741         if (new->d_inode) {
742                 err = ovl_check_sticky(new);
743                 if (err)
744                         goto out;
745
746                 if (d_is_dir(new))
747                         new_is_dir = true;
748
749                 new_type = ovl_path_type(new);
750                 err = -EXDEV;
751                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
752                         goto out;
753
754                 err = 0;
755                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
756                         if (ovl_dentry_lower(old)->d_inode ==
757                             ovl_dentry_lower(new)->d_inode)
758                                 goto out;
759                 }
760                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
761                         if (ovl_dentry_upper(old)->d_inode ==
762                             ovl_dentry_upper(new)->d_inode)
763                                 goto out;
764                 }
765         } else {
766                 if (ovl_dentry_is_opaque(new))
767                         new_type = __OVL_PATH_UPPER;
768                 else
769                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
770         }
771
772         err = ovl_want_write(old);
773         if (err)
774                 goto out;
775
776         err = ovl_copy_up(old);
777         if (err)
778                 goto out_drop_write;
779
780         err = ovl_copy_up(new->d_parent);
781         if (err)
782                 goto out_drop_write;
783         if (!overwrite) {
784                 err = ovl_copy_up(new);
785                 if (err)
786                         goto out_drop_write;
787         }
788
789         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
790         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
791
792         if (old_opaque || new_opaque) {
793                 err = -ENOMEM;
794                 override_cred = prepare_creds();
795                 if (!override_cred)
796                         goto out_drop_write;
797
798                 /*
799                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
800                  * CAP_DAC_OVERRIDE for create in workdir
801                  * CAP_FOWNER for removing whiteout from sticky dir
802                  * CAP_FSETID for chmod of opaque dir
803                  * CAP_CHOWN for chown of opaque dir
804                  */
805                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
806                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
807                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
808                 cap_raise(override_cred->cap_effective, CAP_FSETID);
809                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
810                 old_cred = override_creds(override_cred);
811         }
812
813         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
814                 opaquedir = ovl_check_empty_and_clear(new);
815                 err = PTR_ERR(opaquedir);
816                 if (IS_ERR(opaquedir)) {
817                         opaquedir = NULL;
818                         goto out_revert_creds;
819                 }
820         }
821
822         if (overwrite) {
823                 if (old_opaque) {
824                         if (new->d_inode || !new_opaque) {
825                                 /* Whiteout source */
826                                 flags |= RENAME_WHITEOUT;
827                         } else {
828                                 /* Switch whiteouts */
829                                 flags |= RENAME_EXCHANGE;
830                         }
831                 } else if (is_dir && !new->d_inode && new_opaque) {
832                         flags |= RENAME_EXCHANGE;
833                         cleanup_whiteout = true;
834                 }
835         }
836
837         old_upperdir = ovl_dentry_upper(old->d_parent);
838         new_upperdir = ovl_dentry_upper(new->d_parent);
839
840         trap = lock_rename(new_upperdir, old_upperdir);
841
842         olddentry = ovl_dentry_upper(old);
843         newdentry = ovl_dentry_upper(new);
844         if (newdentry) {
845                 if (opaquedir) {
846                         newdentry = opaquedir;
847                         opaquedir = NULL;
848                 } else {
849                         dget(newdentry);
850                 }
851         } else {
852                 new_create = true;
853                 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
854                                            new->d_name.len);
855                 err = PTR_ERR(newdentry);
856                 if (IS_ERR(newdentry))
857                         goto out_unlock;
858         }
859
860         err = -ESTALE;
861         if (olddentry->d_parent != old_upperdir)
862                 goto out_dput;
863         if (newdentry->d_parent != new_upperdir)
864                 goto out_dput;
865         if (olddentry == trap)
866                 goto out_dput;
867         if (newdentry == trap)
868                 goto out_dput;
869
870         if (is_dir && !old_opaque && new_opaque) {
871                 err = ovl_set_opaque(olddentry);
872                 if (err)
873                         goto out_dput;
874         }
875         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
876                 err = ovl_set_opaque(newdentry);
877                 if (err)
878                         goto out_dput;
879         }
880
881         if (old_opaque || new_opaque) {
882                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
883                                     new_upperdir->d_inode, newdentry,
884                                     flags);
885         } else {
886                 /* No debug for the plain case */
887                 BUG_ON(flags & ~RENAME_EXCHANGE);
888                 err = vfs_rename(old_upperdir->d_inode, olddentry,
889                                  new_upperdir->d_inode, newdentry,
890                                  NULL, flags);
891         }
892
893         if (err) {
894                 if (is_dir && !old_opaque && new_opaque)
895                         ovl_remove_opaque(olddentry);
896                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
897                         ovl_remove_opaque(newdentry);
898                 goto out_dput;
899         }
900
901         if (is_dir && old_opaque && !new_opaque)
902                 ovl_remove_opaque(olddentry);
903         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
904                 ovl_remove_opaque(newdentry);
905
906         if (old_opaque != new_opaque) {
907                 ovl_dentry_set_opaque(old, new_opaque);
908                 if (!overwrite)
909                         ovl_dentry_set_opaque(new, old_opaque);
910         }
911
912         if (cleanup_whiteout)
913                 ovl_cleanup(old_upperdir->d_inode, newdentry);
914
915         ovl_dentry_version_inc(old->d_parent);
916         ovl_dentry_version_inc(new->d_parent);
917
918 out_dput:
919         dput(newdentry);
920 out_unlock:
921         unlock_rename(new_upperdir, old_upperdir);
922 out_revert_creds:
923         if (old_opaque || new_opaque) {
924                 revert_creds(old_cred);
925                 put_cred(override_cred);
926         }
927 out_drop_write:
928         ovl_drop_write(old);
929 out:
930         dput(opaquedir);
931         return err;
932 }
933
934 const struct inode_operations ovl_dir_inode_operations = {
935         .lookup         = ovl_lookup,
936         .mkdir          = ovl_mkdir,
937         .symlink        = ovl_symlink,
938         .unlink         = ovl_unlink,
939         .rmdir          = ovl_rmdir,
940         .rename2        = ovl_rename2,
941         .link           = ovl_link,
942         .setattr        = ovl_setattr,
943         .create         = ovl_create,
944         .mknod          = ovl_mknod,
945         .permission     = ovl_permission,
946         .getattr        = ovl_dir_getattr,
947         .setxattr       = ovl_setxattr,
948         .getxattr       = ovl_getxattr,
949         .listxattr      = ovl_listxattr,
950         .removexattr    = ovl_removexattr,
951 };