3 * Copyright (C) 2011 Novell Inc.
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.
11 #include <linux/namei.h>
12 #include <linux/xattr.h>
13 #include <linux/security.h>
14 #include <linux/cred.h>
15 #include "overlayfs.h"
17 void ovl_cleanup(struct inode
*wdir
, struct dentry
*wdentry
)
22 if (d_is_dir(wdentry
))
23 err
= ovl_do_rmdir(wdir
, wdentry
);
25 err
= ovl_do_unlink(wdir
, wdentry
);
29 pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
34 struct dentry
*ovl_lookup_temp(struct dentry
*workdir
, struct dentry
*dentry
)
39 snprintf(name
, sizeof(name
), "#%lx", (unsigned long) dentry
);
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
);
51 /* caller holds i_mutex on workdir */
52 static struct dentry
*ovl_whiteout(struct dentry
*workdir
,
53 struct dentry
*dentry
)
56 struct dentry
*whiteout
;
57 struct inode
*wdir
= workdir
->d_inode
;
59 whiteout
= ovl_lookup_temp(workdir
, dentry
);
63 err
= ovl_do_whiteout(wdir
, whiteout
);
66 whiteout
= ERR_PTR(err
);
72 int ovl_create_real(struct inode
*dir
, struct dentry
*newdentry
,
73 struct kstat
*stat
, const char *link
,
74 struct dentry
*hardlink
, bool debug
)
78 if (newdentry
->d_inode
)
82 err
= ovl_do_link(hardlink
, dir
, newdentry
, debug
);
84 switch (stat
->mode
& S_IFMT
) {
86 err
= ovl_do_create(dir
, newdentry
, stat
->mode
, debug
);
90 err
= ovl_do_mkdir(dir
, newdentry
, stat
->mode
, debug
);
97 err
= ovl_do_mknod(dir
, newdentry
,
98 stat
->mode
, stat
->rdev
, debug
);
102 err
= ovl_do_symlink(dir
, newdentry
, link
, debug
);
109 if (!err
&& WARN_ON(!newdentry
->d_inode
)) {
111 * Not quite sure if non-instantiated dentry is legal or not.
112 * VFS doesn't seem to care so check and warn here.
119 static int ovl_set_opaque(struct dentry
*upperdentry
)
121 return ovl_do_setxattr(upperdentry
, OVL_XATTR_OPAQUE
, "y", 1, 0);
124 static void ovl_remove_opaque(struct dentry
*upperdentry
)
128 err
= ovl_do_removexattr(upperdentry
, OVL_XATTR_OPAQUE
);
130 pr_warn("overlayfs: failed to remove opaque from '%s' (%i)\n",
131 upperdentry
->d_name
.name
, err
);
135 static int ovl_dir_getattr(struct vfsmount
*mnt
, struct dentry
*dentry
,
139 enum ovl_path_type type
;
140 struct path realpath
;
142 type
= ovl_path_real(dentry
, &realpath
);
143 err
= vfs_getattr(&realpath
, stat
);
147 stat
->dev
= dentry
->d_sb
->s_dev
;
148 stat
->ino
= dentry
->d_inode
->i_ino
;
151 * It's probably not worth it to count subdirs to get the
152 * correct link count. nlink=1 seems to pacify 'find' and
155 if (OVL_TYPE_MERGE(type
))
161 static int ovl_create_upper(struct dentry
*dentry
, struct inode
*inode
,
162 struct kstat
*stat
, const char *link
,
163 struct dentry
*hardlink
)
165 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
166 struct inode
*udir
= upperdir
->d_inode
;
167 struct dentry
*newdentry
;
170 inode_lock_nested(udir
, I_MUTEX_PARENT
);
171 newdentry
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
173 err
= PTR_ERR(newdentry
);
174 if (IS_ERR(newdentry
))
176 err
= ovl_create_real(udir
, newdentry
, stat
, link
, hardlink
, false);
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
);
192 static int ovl_lock_rename_workdir(struct dentry
*workdir
,
193 struct dentry
*upperdir
)
195 /* Workdir should not be the same as upperdir */
196 if (workdir
== upperdir
)
199 /* Workdir should not be subdir of upperdir and vice versa */
200 if (lock_rename(workdir
, upperdir
) != NULL
)
206 unlock_rename(workdir
, upperdir
);
208 pr_err("overlayfs: failed to lock workdir+upperdir\n");
212 static struct dentry
*ovl_clear_empty(struct dentry
*dentry
,
213 struct list_head
*list
)
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
;
225 if (WARN_ON(!workdir
))
226 return ERR_PTR(-EROFS
);
228 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
232 ovl_path_upper(dentry
, &upperpath
);
233 err
= vfs_getattr(&upperpath
, &stat
);
238 if (!S_ISDIR(stat
.mode
))
240 upper
= upperpath
.dentry
;
241 if (upper
->d_parent
->d_inode
!= udir
)
244 opaquedir
= ovl_lookup_temp(workdir
, dentry
);
245 err
= PTR_ERR(opaquedir
);
246 if (IS_ERR(opaquedir
))
249 err
= ovl_create_real(wdir
, opaquedir
, &stat
, NULL
, NULL
, true);
253 err
= ovl_copy_xattr(upper
, opaquedir
);
257 err
= ovl_set_opaque(opaquedir
);
261 inode_lock(opaquedir
->d_inode
);
262 err
= ovl_set_attr(opaquedir
, &stat
);
263 inode_unlock(opaquedir
->d_inode
);
267 err
= ovl_do_rename(wdir
, opaquedir
, udir
, upper
, RENAME_EXCHANGE
);
271 ovl_cleanup_whiteouts(upper
, list
);
272 ovl_cleanup(wdir
, upper
);
273 unlock_rename(workdir
, upperdir
);
275 /* dentry's upper doesn't match now, get rid of it */
281 ovl_cleanup(wdir
, opaquedir
);
285 unlock_rename(workdir
, upperdir
);
290 static struct dentry
*ovl_check_empty_and_clear(struct dentry
*dentry
)
293 struct dentry
*ret
= NULL
;
296 err
= ovl_check_empty_dir(dentry
, &list
);
301 * If no upperdentry then skip clearing whiteouts.
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.
307 if (ovl_dentry_upper(dentry
))
308 ret
= ovl_clear_empty(dentry
, &list
);
311 ovl_cache_free(&list
);
316 static int ovl_create_over_whiteout(struct dentry
*dentry
, struct inode
*inode
,
317 struct kstat
*stat
, const char *link
,
318 struct dentry
*hardlink
)
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
;
328 if (WARN_ON(!workdir
))
331 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
335 newdentry
= ovl_lookup_temp(workdir
, dentry
);
336 err
= PTR_ERR(newdentry
);
337 if (IS_ERR(newdentry
))
340 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
342 err
= PTR_ERR(upper
);
346 err
= ovl_create_real(wdir
, newdentry
, stat
, link
, hardlink
, true);
350 if (S_ISDIR(stat
->mode
)) {
351 err
= ovl_set_opaque(newdentry
);
355 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
,
360 ovl_cleanup(wdir
, upper
);
362 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
, 0);
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
);
376 unlock_rename(workdir
, upperdir
);
381 ovl_cleanup(wdir
, newdentry
);
385 static int ovl_create_or_link(struct dentry
*dentry
, int mode
, dev_t rdev
,
386 const char *link
, struct dentry
*hardlink
)
390 struct kstat stat
= {
396 inode
= ovl_new_inode(dentry
->d_sb
, mode
, dentry
->d_fsdata
);
400 err
= ovl_copy_up(dentry
->d_parent
);
404 if (!ovl_dentry_is_opaque(dentry
)) {
405 err
= ovl_create_upper(dentry
, inode
, &stat
, link
, hardlink
);
407 const struct cred
*old_cred
;
408 struct cred
*override_cred
;
410 old_cred
= ovl_override_creds(dentry
->d_sb
);
413 override_cred
= prepare_creds();
415 override_cred
->fsuid
= old_cred
->fsuid
;
416 override_cred
->fsgid
= old_cred
->fsgid
;
417 put_cred(override_creds(override_cred
));
418 put_cred(override_cred
);
420 err
= ovl_create_over_whiteout(dentry
, inode
, &stat
,
423 revert_creds(old_cred
);
434 static int ovl_create_object(struct dentry
*dentry
, int mode
, dev_t rdev
,
439 err
= ovl_want_write(dentry
);
441 err
= ovl_create_or_link(dentry
, mode
, rdev
, link
, NULL
);
442 ovl_drop_write(dentry
);
448 static int ovl_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
451 return ovl_create_object(dentry
, (mode
& 07777) | S_IFREG
, 0, NULL
);
454 static int ovl_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
456 return ovl_create_object(dentry
, (mode
& 07777) | S_IFDIR
, 0, NULL
);
459 static int ovl_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
462 /* Don't allow creation of "whiteout" on overlay */
463 if (S_ISCHR(mode
) && rdev
== WHITEOUT_DEV
)
466 return ovl_create_object(dentry
, mode
, rdev
, NULL
);
469 static int ovl_symlink(struct inode
*dir
, struct dentry
*dentry
,
472 return ovl_create_object(dentry
, S_IFLNK
, 0, link
);
475 static int ovl_link(struct dentry
*old
, struct inode
*newdir
,
479 struct dentry
*upper
;
481 err
= ovl_want_write(old
);
485 err
= ovl_copy_up(old
);
489 upper
= ovl_dentry_upper(old
);
490 err
= ovl_create_or_link(new, upper
->d_inode
->i_mode
, 0, NULL
, upper
);
498 static int ovl_remove_and_whiteout(struct dentry
*dentry
, bool is_dir
)
500 struct dentry
*workdir
= ovl_workdir(dentry
);
501 struct inode
*wdir
= workdir
->d_inode
;
502 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
503 struct inode
*udir
= upperdir
->d_inode
;
504 struct dentry
*whiteout
;
505 struct dentry
*upper
;
506 struct dentry
*opaquedir
= NULL
;
509 if (WARN_ON(!workdir
))
513 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry
))) {
514 opaquedir
= ovl_check_empty_and_clear(dentry
);
515 err
= PTR_ERR(opaquedir
);
516 if (IS_ERR(opaquedir
))
522 * When removing an empty opaque directory, then it
523 * makes no sense to replace it with an exact replica of
524 * itself. But emptiness still needs to be checked.
526 err
= ovl_check_empty_dir(dentry
, &list
);
527 ovl_cache_free(&list
);
533 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
537 whiteout
= ovl_whiteout(workdir
, dentry
);
538 err
= PTR_ERR(whiteout
);
539 if (IS_ERR(whiteout
))
542 upper
= ovl_dentry_upper(dentry
);
544 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
546 err
= PTR_ERR(upper
);
550 err
= ovl_do_rename(wdir
, whiteout
, udir
, upper
, 0);
560 if (upper
->d_parent
!= upperdir
)
564 flags
|= RENAME_EXCHANGE
;
566 err
= ovl_do_rename(wdir
, whiteout
, udir
, upper
, flags
);
571 ovl_cleanup(wdir
, upper
);
573 ovl_dentry_version_inc(dentry
->d_parent
);
578 unlock_rename(workdir
, upperdir
);
585 ovl_cleanup(wdir
, whiteout
);
589 static int ovl_remove_upper(struct dentry
*dentry
, bool is_dir
)
591 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
592 struct inode
*dir
= upperdir
->d_inode
;
593 struct dentry
*upper
;
596 inode_lock_nested(dir
, I_MUTEX_PARENT
);
597 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
599 err
= PTR_ERR(upper
);
604 if (upper
== ovl_dentry_upper(dentry
)) {
606 err
= vfs_rmdir(dir
, upper
);
608 err
= vfs_unlink(dir
, upper
, NULL
);
609 ovl_dentry_version_inc(dentry
->d_parent
);
614 * Keeping this dentry hashed would mean having to release
615 * upperpath/lowerpath, which could only be done if we are the
616 * sole user of this dentry. Too tricky... Just unhash for
627 static inline int ovl_check_sticky(struct dentry
*dentry
)
629 struct inode
*dir
= ovl_dentry_real(dentry
->d_parent
)->d_inode
;
630 struct inode
*inode
= ovl_dentry_real(dentry
)->d_inode
;
632 if (check_sticky(dir
, inode
))
638 static int ovl_do_remove(struct dentry
*dentry
, bool is_dir
)
640 enum ovl_path_type type
;
643 err
= ovl_check_sticky(dentry
);
647 err
= ovl_want_write(dentry
);
651 err
= ovl_copy_up(dentry
->d_parent
);
655 type
= ovl_path_type(dentry
);
656 if (OVL_TYPE_PURE_UPPER(type
)) {
657 err
= ovl_remove_upper(dentry
, is_dir
);
659 const struct cred
*old_cred
= ovl_override_creds(dentry
->d_sb
);
661 err
= ovl_remove_and_whiteout(dentry
, is_dir
);
663 revert_creds(old_cred
);
666 ovl_drop_write(dentry
);
671 static int ovl_unlink(struct inode
*dir
, struct dentry
*dentry
)
673 return ovl_do_remove(dentry
, false);
676 static int ovl_rmdir(struct inode
*dir
, struct dentry
*dentry
)
678 return ovl_do_remove(dentry
, true);
681 static int ovl_rename2(struct inode
*olddir
, struct dentry
*old
,
682 struct inode
*newdir
, struct dentry
*new,
686 enum ovl_path_type old_type
;
687 enum ovl_path_type new_type
;
688 struct dentry
*old_upperdir
;
689 struct dentry
*new_upperdir
;
690 struct dentry
*olddentry
;
691 struct dentry
*newdentry
;
695 bool cleanup_whiteout
= false;
696 bool overwrite
= !(flags
& RENAME_EXCHANGE
);
697 bool is_dir
= d_is_dir(old
);
698 bool new_is_dir
= false;
699 struct dentry
*opaquedir
= NULL
;
700 const struct cred
*old_cred
= NULL
;
703 if (flags
& ~(RENAME_EXCHANGE
| RENAME_NOREPLACE
))
706 flags
&= ~RENAME_NOREPLACE
;
708 err
= ovl_check_sticky(old
);
712 /* Don't copy up directory trees */
713 old_type
= ovl_path_type(old
);
715 if (OVL_TYPE_MERGE_OR_LOWER(old_type
) && is_dir
)
719 err
= ovl_check_sticky(new);
726 new_type
= ovl_path_type(new);
728 if (!overwrite
&& OVL_TYPE_MERGE_OR_LOWER(new_type
) && new_is_dir
)
732 if (!OVL_TYPE_UPPER(new_type
) && !OVL_TYPE_UPPER(old_type
)) {
733 if (ovl_dentry_lower(old
)->d_inode
==
734 ovl_dentry_lower(new)->d_inode
)
737 if (OVL_TYPE_UPPER(new_type
) && OVL_TYPE_UPPER(old_type
)) {
738 if (ovl_dentry_upper(old
)->d_inode
==
739 ovl_dentry_upper(new)->d_inode
)
743 if (ovl_dentry_is_opaque(new))
744 new_type
= __OVL_PATH_UPPER
;
746 new_type
= __OVL_PATH_UPPER
| __OVL_PATH_PURE
;
749 err
= ovl_want_write(old
);
753 err
= ovl_copy_up(old
);
757 err
= ovl_copy_up(new->d_parent
);
761 err
= ovl_copy_up(new);
766 old_opaque
= !OVL_TYPE_PURE_UPPER(old_type
);
767 new_opaque
= !OVL_TYPE_PURE_UPPER(new_type
);
769 if (old_opaque
|| new_opaque
)
770 old_cred
= ovl_override_creds(old
->d_sb
);
772 if (overwrite
&& OVL_TYPE_MERGE_OR_LOWER(new_type
) && new_is_dir
) {
773 opaquedir
= ovl_check_empty_and_clear(new);
774 err
= PTR_ERR(opaquedir
);
775 if (IS_ERR(opaquedir
)) {
777 goto out_revert_creds
;
783 if (new->d_inode
|| !new_opaque
) {
784 /* Whiteout source */
785 flags
|= RENAME_WHITEOUT
;
787 /* Switch whiteouts */
788 flags
|= RENAME_EXCHANGE
;
790 } else if (is_dir
&& !new->d_inode
&& new_opaque
) {
791 flags
|= RENAME_EXCHANGE
;
792 cleanup_whiteout
= true;
796 old_upperdir
= ovl_dentry_upper(old
->d_parent
);
797 new_upperdir
= ovl_dentry_upper(new->d_parent
);
799 trap
= lock_rename(new_upperdir
, old_upperdir
);
802 olddentry
= lookup_one_len(old
->d_name
.name
, old_upperdir
,
804 err
= PTR_ERR(olddentry
);
805 if (IS_ERR(olddentry
))
809 if (olddentry
!= ovl_dentry_upper(old
))
812 newdentry
= lookup_one_len(new->d_name
.name
, new_upperdir
,
814 err
= PTR_ERR(newdentry
);
815 if (IS_ERR(newdentry
))
819 if (ovl_dentry_upper(new)) {
821 if (newdentry
!= opaquedir
)
824 if (newdentry
!= ovl_dentry_upper(new))
828 if (!d_is_negative(newdentry
) &&
829 (!new_opaque
|| !ovl_is_whiteout(newdentry
)))
833 if (olddentry
== trap
)
835 if (newdentry
== trap
)
838 if (is_dir
&& !old_opaque
&& new_opaque
) {
839 err
= ovl_set_opaque(olddentry
);
843 if (!overwrite
&& new_is_dir
&& old_opaque
&& !new_opaque
) {
844 err
= ovl_set_opaque(newdentry
);
849 if (old_opaque
|| new_opaque
) {
850 err
= ovl_do_rename(old_upperdir
->d_inode
, olddentry
,
851 new_upperdir
->d_inode
, newdentry
,
854 /* No debug for the plain case */
855 BUG_ON(flags
& ~RENAME_EXCHANGE
);
856 err
= vfs_rename(old_upperdir
->d_inode
, olddentry
,
857 new_upperdir
->d_inode
, newdentry
,
862 if (is_dir
&& !old_opaque
&& new_opaque
)
863 ovl_remove_opaque(olddentry
);
864 if (!overwrite
&& new_is_dir
&& old_opaque
&& !new_opaque
)
865 ovl_remove_opaque(newdentry
);
869 if (is_dir
&& old_opaque
&& !new_opaque
)
870 ovl_remove_opaque(olddentry
);
871 if (!overwrite
&& new_is_dir
&& !old_opaque
&& new_opaque
)
872 ovl_remove_opaque(newdentry
);
875 * Old dentry now lives in different location. Dentries in
876 * lowerstack are stale. We cannot drop them here because
877 * access to them is lockless. This could be only pure upper
878 * or opaque directory - numlower is zero. Or upper non-dir
879 * entry - its pureness is tracked by flag opaque.
881 if (old_opaque
!= new_opaque
) {
882 ovl_dentry_set_opaque(old
, new_opaque
);
884 ovl_dentry_set_opaque(new, old_opaque
);
887 if (cleanup_whiteout
)
888 ovl_cleanup(old_upperdir
->d_inode
, newdentry
);
890 ovl_dentry_version_inc(old
->d_parent
);
891 ovl_dentry_version_inc(new->d_parent
);
898 unlock_rename(new_upperdir
, old_upperdir
);
900 if (old_opaque
|| new_opaque
)
901 revert_creds(old_cred
);
909 const struct inode_operations ovl_dir_inode_operations
= {
910 .lookup
= ovl_lookup
,
912 .symlink
= ovl_symlink
,
913 .unlink
= ovl_unlink
,
915 .rename2
= ovl_rename2
,
917 .setattr
= ovl_setattr
,
918 .create
= ovl_create
,
920 .permission
= ovl_permission
,
921 .getattr
= ovl_dir_getattr
,
922 .setxattr
= ovl_setxattr
,
923 .getxattr
= ovl_getxattr
,
924 .listxattr
= ovl_listxattr
,
925 .removexattr
= ovl_removexattr
,