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TOMOYO Linux Cross Reference
Linux/fs/overlayfs/dir.c

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  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         inode_lock_nested(udir, 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         inode_unlock(udir);
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         inode_lock(opaquedir->d_inode);
262         err = ovl_set_attr(opaquedir, &stat);
263         inode_unlock(opaquedir->d_inode);
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         inode_lock_nested(dir, 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         if (!err)
622                 d_drop(dentry);
623         inode_unlock(dir);
624 
625         return err;
626 }
627 
628 static inline int ovl_check_sticky(struct dentry *dentry)
629 {
630         struct inode *dir = ovl_dentry_real(dentry->d_parent)->d_inode;
631         struct inode *inode = ovl_dentry_real(dentry)->d_inode;
632 
633         if (check_sticky(dir, inode))
634                 return -EPERM;
635 
636         return 0;
637 }
638 
639 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
640 {
641         enum ovl_path_type type;
642         int err;
643 
644         err = ovl_check_sticky(dentry);
645         if (err)
646                 goto out;
647 
648         err = ovl_want_write(dentry);
649         if (err)
650                 goto out;
651 
652         err = ovl_copy_up(dentry->d_parent);
653         if (err)
654                 goto out_drop_write;
655 
656         type = ovl_path_type(dentry);
657         if (OVL_TYPE_PURE_UPPER(type)) {
658                 err = ovl_remove_upper(dentry, is_dir);
659         } else {
660                 const struct cred *old_cred;
661                 struct cred *override_cred;
662 
663                 err = -ENOMEM;
664                 override_cred = prepare_creds();
665                 if (!override_cred)
666                         goto out_drop_write;
667 
668                 /*
669                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
670                  * CAP_DAC_OVERRIDE for create in workdir, rename
671                  * CAP_FOWNER for removing whiteout from sticky dir
672                  * CAP_FSETID for chmod of opaque dir
673                  * CAP_CHOWN for chown of opaque dir
674                  */
675                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
676                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
677                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
678                 cap_raise(override_cred->cap_effective, CAP_FSETID);
679                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
680                 old_cred = override_creds(override_cred);
681 
682                 err = ovl_remove_and_whiteout(dentry, is_dir);
683 
684                 revert_creds(old_cred);
685                 put_cred(override_cred);
686         }
687 out_drop_write:
688         ovl_drop_write(dentry);
689 out:
690         return err;
691 }
692 
693 static int ovl_unlink(struct inode *dir, struct dentry *dentry)
694 {
695         return ovl_do_remove(dentry, false);
696 }
697 
698 static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
699 {
700         return ovl_do_remove(dentry, true);
701 }
702 
703 static int ovl_rename2(struct inode *olddir, struct dentry *old,
704                        struct inode *newdir, struct dentry *new,
705                        unsigned int flags)
706 {
707         int err;
708         enum ovl_path_type old_type;
709         enum ovl_path_type new_type;
710         struct dentry *old_upperdir;
711         struct dentry *new_upperdir;
712         struct dentry *olddentry;
713         struct dentry *newdentry;
714         struct dentry *trap;
715         bool old_opaque;
716         bool new_opaque;
717         bool new_create = false;
718         bool cleanup_whiteout = false;
719         bool overwrite = !(flags & RENAME_EXCHANGE);
720         bool is_dir = d_is_dir(old);
721         bool new_is_dir = false;
722         struct dentry *opaquedir = NULL;
723         const struct cred *old_cred = NULL;
724         struct cred *override_cred = NULL;
725 
726         err = -EINVAL;
727         if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
728                 goto out;
729 
730         flags &= ~RENAME_NOREPLACE;
731 
732         err = ovl_check_sticky(old);
733         if (err)
734                 goto out;
735 
736         /* Don't copy up directory trees */
737         old_type = ovl_path_type(old);
738         err = -EXDEV;
739         if (OVL_TYPE_MERGE_OR_LOWER(old_type) && is_dir)
740                 goto out;
741 
742         if (new->d_inode) {
743                 err = ovl_check_sticky(new);
744                 if (err)
745                         goto out;
746 
747                 if (d_is_dir(new))
748                         new_is_dir = true;
749 
750                 new_type = ovl_path_type(new);
751                 err = -EXDEV;
752                 if (!overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir)
753                         goto out;
754 
755                 err = 0;
756                 if (!OVL_TYPE_UPPER(new_type) && !OVL_TYPE_UPPER(old_type)) {
757                         if (ovl_dentry_lower(old)->d_inode ==
758                             ovl_dentry_lower(new)->d_inode)
759                                 goto out;
760                 }
761                 if (OVL_TYPE_UPPER(new_type) && OVL_TYPE_UPPER(old_type)) {
762                         if (ovl_dentry_upper(old)->d_inode ==
763                             ovl_dentry_upper(new)->d_inode)
764                                 goto out;
765                 }
766         } else {
767                 if (ovl_dentry_is_opaque(new))
768                         new_type = __OVL_PATH_UPPER;
769                 else
770                         new_type = __OVL_PATH_UPPER | __OVL_PATH_PURE;
771         }
772 
773         err = ovl_want_write(old);
774         if (err)
775                 goto out;
776 
777         err = ovl_copy_up(old);
778         if (err)
779                 goto out_drop_write;
780 
781         err = ovl_copy_up(new->d_parent);
782         if (err)
783                 goto out_drop_write;
784         if (!overwrite) {
785                 err = ovl_copy_up(new);
786                 if (err)
787                         goto out_drop_write;
788         }
789 
790         old_opaque = !OVL_TYPE_PURE_UPPER(old_type);
791         new_opaque = !OVL_TYPE_PURE_UPPER(new_type);
792 
793         if (old_opaque || new_opaque) {
794                 err = -ENOMEM;
795                 override_cred = prepare_creds();
796                 if (!override_cred)
797                         goto out_drop_write;
798 
799                 /*
800                  * CAP_SYS_ADMIN for setting xattr on whiteout, opaque dir
801                  * CAP_DAC_OVERRIDE for create in workdir
802                  * CAP_FOWNER for removing whiteout from sticky dir
803                  * CAP_FSETID for chmod of opaque dir
804                  * CAP_CHOWN for chown of opaque dir
805                  */
806                 cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
807                 cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
808                 cap_raise(override_cred->cap_effective, CAP_FOWNER);
809                 cap_raise(override_cred->cap_effective, CAP_FSETID);
810                 cap_raise(override_cred->cap_effective, CAP_CHOWN);
811                 old_cred = override_creds(override_cred);
812         }
813 
814         if (overwrite && OVL_TYPE_MERGE_OR_LOWER(new_type) && new_is_dir) {
815                 opaquedir = ovl_check_empty_and_clear(new);
816                 err = PTR_ERR(opaquedir);
817                 if (IS_ERR(opaquedir)) {
818                         opaquedir = NULL;
819                         goto out_revert_creds;
820                 }
821         }
822 
823         if (overwrite) {
824                 if (old_opaque) {
825                         if (new->d_inode || !new_opaque) {
826                                 /* Whiteout source */
827                                 flags |= RENAME_WHITEOUT;
828                         } else {
829                                 /* Switch whiteouts */
830                                 flags |= RENAME_EXCHANGE;
831                         }
832                 } else if (is_dir && !new->d_inode && new_opaque) {
833                         flags |= RENAME_EXCHANGE;
834                         cleanup_whiteout = true;
835                 }
836         }
837 
838         old_upperdir = ovl_dentry_upper(old->d_parent);
839         new_upperdir = ovl_dentry_upper(new->d_parent);
840 
841         trap = lock_rename(new_upperdir, old_upperdir);
842 
843         olddentry = ovl_dentry_upper(old);
844         newdentry = ovl_dentry_upper(new);
845         if (newdentry) {
846                 if (opaquedir) {
847                         newdentry = opaquedir;
848                         opaquedir = NULL;
849                 } else {
850                         dget(newdentry);
851                 }
852         } else {
853                 new_create = true;
854                 newdentry = lookup_one_len(new->d_name.name, new_upperdir,
855                                            new->d_name.len);
856                 err = PTR_ERR(newdentry);
857                 if (IS_ERR(newdentry))
858                         goto out_unlock;
859         }
860 
861         err = -ESTALE;
862         if (olddentry->d_parent != old_upperdir)
863                 goto out_dput;
864         if (newdentry->d_parent != new_upperdir)
865                 goto out_dput;
866         if (olddentry == trap)
867                 goto out_dput;
868         if (newdentry == trap)
869                 goto out_dput;
870 
871         if (is_dir && !old_opaque && new_opaque) {
872                 err = ovl_set_opaque(olddentry);
873                 if (err)
874                         goto out_dput;
875         }
876         if (!overwrite && new_is_dir && old_opaque && !new_opaque) {
877                 err = ovl_set_opaque(newdentry);
878                 if (err)
879                         goto out_dput;
880         }
881 
882         if (old_opaque || new_opaque) {
883                 err = ovl_do_rename(old_upperdir->d_inode, olddentry,
884                                     new_upperdir->d_inode, newdentry,
885                                     flags);
886         } else {
887                 /* No debug for the plain case */
888                 BUG_ON(flags & ~RENAME_EXCHANGE);
889                 err = vfs_rename(old_upperdir->d_inode, olddentry,
890                                  new_upperdir->d_inode, newdentry,
891                                  NULL, flags);
892         }
893 
894         if (err) {
895                 if (is_dir && !old_opaque && new_opaque)
896                         ovl_remove_opaque(olddentry);
897                 if (!overwrite && new_is_dir && old_opaque && !new_opaque)
898                         ovl_remove_opaque(newdentry);
899                 goto out_dput;
900         }
901 
902         if (is_dir && old_opaque && !new_opaque)
903                 ovl_remove_opaque(olddentry);
904         if (!overwrite && new_is_dir && !old_opaque && new_opaque)
905                 ovl_remove_opaque(newdentry);
906 
907         /*
908          * Old dentry now lives in different location. Dentries in
909          * lowerstack are stale. We cannot drop them here because
910          * access to them is lockless. This could be only pure upper
911          * or opaque directory - numlower is zero. Or upper non-dir
912          * entry - its pureness is tracked by flag opaque.
913          */
914         if (old_opaque != new_opaque) {
915                 ovl_dentry_set_opaque(old, new_opaque);
916                 if (!overwrite)
917                         ovl_dentry_set_opaque(new, old_opaque);
918         }
919 
920         if (cleanup_whiteout)
921                 ovl_cleanup(old_upperdir->d_inode, newdentry);
922 
923         ovl_dentry_version_inc(old->d_parent);
924         ovl_dentry_version_inc(new->d_parent);
925 
926 out_dput:
927         dput(newdentry);
928 out_unlock:
929         unlock_rename(new_upperdir, old_upperdir);
930 out_revert_creds:
931         if (old_opaque || new_opaque) {
932                 revert_creds(old_cred);
933                 put_cred(override_cred);
934         }
935 out_drop_write:
936         ovl_drop_write(old);
937 out:
938         dput(opaquedir);
939         return err;
940 }
941 
942 const struct inode_operations ovl_dir_inode_operations = {
943         .lookup         = ovl_lookup,
944         .mkdir          = ovl_mkdir,
945         .symlink        = ovl_symlink,
946         .unlink         = ovl_unlink,
947         .rmdir          = ovl_rmdir,
948         .rename2        = ovl_rename2,
949         .link           = ovl_link,
950         .setattr        = ovl_setattr,
951         .create         = ovl_create,
952         .mknod          = ovl_mknod,
953         .permission     = ovl_permission,
954         .getattr        = ovl_dir_getattr,
955         .setxattr       = ovl_setxattr,
956         .getxattr       = ovl_getxattr,
957         .listxattr      = ovl_listxattr,
958         .removexattr    = ovl_removexattr,
959 };
960 

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