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
;
141 const struct cred
*old_cred
;
143 type
= ovl_path_real(dentry
, &realpath
);
144 old_cred
= ovl_override_creds(dentry
->d_sb
);
145 err
= vfs_getattr(&realpath
, stat
);
146 revert_creds(old_cred
);
150 stat
->dev
= dentry
->d_sb
->s_dev
;
151 stat
->ino
= dentry
->d_inode
->i_ino
;
154 * It's probably not worth it to count subdirs to get the
155 * correct link count. nlink=1 seems to pacify 'find' and
158 if (OVL_TYPE_MERGE(type
))
164 /* Common operations required to be done after creation of file on upper */
165 static void ovl_instantiate(struct dentry
*dentry
, struct inode
*inode
,
166 struct dentry
*newdentry
)
168 ovl_dentry_version_inc(dentry
->d_parent
);
169 ovl_dentry_update(dentry
, newdentry
);
170 ovl_copyattr(newdentry
->d_inode
, inode
);
171 d_instantiate(dentry
, inode
);
174 static int ovl_create_upper(struct dentry
*dentry
, struct inode
*inode
,
175 struct kstat
*stat
, const char *link
,
176 struct dentry
*hardlink
)
178 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
179 struct inode
*udir
= upperdir
->d_inode
;
180 struct dentry
*newdentry
;
183 inode_lock_nested(udir
, I_MUTEX_PARENT
);
184 newdentry
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
186 err
= PTR_ERR(newdentry
);
187 if (IS_ERR(newdentry
))
189 err
= ovl_create_real(udir
, newdentry
, stat
, link
, hardlink
, false);
193 ovl_instantiate(dentry
, inode
, newdentry
);
202 static int ovl_lock_rename_workdir(struct dentry
*workdir
,
203 struct dentry
*upperdir
)
205 /* Workdir should not be the same as upperdir */
206 if (workdir
== upperdir
)
209 /* Workdir should not be subdir of upperdir and vice versa */
210 if (lock_rename(workdir
, upperdir
) != NULL
)
216 unlock_rename(workdir
, upperdir
);
218 pr_err("overlayfs: failed to lock workdir+upperdir\n");
222 static struct dentry
*ovl_clear_empty(struct dentry
*dentry
,
223 struct list_head
*list
)
225 struct dentry
*workdir
= ovl_workdir(dentry
);
226 struct inode
*wdir
= workdir
->d_inode
;
227 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
228 struct inode
*udir
= upperdir
->d_inode
;
229 struct path upperpath
;
230 struct dentry
*upper
;
231 struct dentry
*opaquedir
;
235 if (WARN_ON(!workdir
))
236 return ERR_PTR(-EROFS
);
238 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
242 ovl_path_upper(dentry
, &upperpath
);
243 err
= vfs_getattr(&upperpath
, &stat
);
248 if (!S_ISDIR(stat
.mode
))
250 upper
= upperpath
.dentry
;
251 if (upper
->d_parent
->d_inode
!= udir
)
254 opaquedir
= ovl_lookup_temp(workdir
, dentry
);
255 err
= PTR_ERR(opaquedir
);
256 if (IS_ERR(opaquedir
))
259 err
= ovl_create_real(wdir
, opaquedir
, &stat
, NULL
, NULL
, true);
263 err
= ovl_copy_xattr(upper
, opaquedir
);
267 err
= ovl_set_opaque(opaquedir
);
271 inode_lock(opaquedir
->d_inode
);
272 err
= ovl_set_attr(opaquedir
, &stat
);
273 inode_unlock(opaquedir
->d_inode
);
277 err
= ovl_do_rename(wdir
, opaquedir
, udir
, upper
, RENAME_EXCHANGE
);
281 ovl_cleanup_whiteouts(upper
, list
);
282 ovl_cleanup(wdir
, upper
);
283 unlock_rename(workdir
, upperdir
);
285 /* dentry's upper doesn't match now, get rid of it */
291 ovl_cleanup(wdir
, opaquedir
);
295 unlock_rename(workdir
, upperdir
);
300 static struct dentry
*ovl_check_empty_and_clear(struct dentry
*dentry
)
303 struct dentry
*ret
= NULL
;
306 err
= ovl_check_empty_dir(dentry
, &list
);
311 * If no upperdentry then skip clearing whiteouts.
313 * Can race with copy-up, since we don't hold the upperdir
314 * mutex. Doesn't matter, since copy-up can't create a
315 * non-empty directory from an empty one.
317 if (ovl_dentry_upper(dentry
))
318 ret
= ovl_clear_empty(dentry
, &list
);
321 ovl_cache_free(&list
);
326 static int ovl_create_over_whiteout(struct dentry
*dentry
, struct inode
*inode
,
327 struct kstat
*stat
, const char *link
,
328 struct dentry
*hardlink
)
330 struct dentry
*workdir
= ovl_workdir(dentry
);
331 struct inode
*wdir
= workdir
->d_inode
;
332 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
333 struct inode
*udir
= upperdir
->d_inode
;
334 struct dentry
*upper
;
335 struct dentry
*newdentry
;
338 if (WARN_ON(!workdir
))
341 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
345 newdentry
= ovl_lookup_temp(workdir
, dentry
);
346 err
= PTR_ERR(newdentry
);
347 if (IS_ERR(newdentry
))
350 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
352 err
= PTR_ERR(upper
);
356 err
= ovl_create_real(wdir
, newdentry
, stat
, link
, hardlink
, true);
361 * mode could have been mutilated due to umask (e.g. sgid directory)
363 if (!S_ISLNK(stat
->mode
) && newdentry
->d_inode
->i_mode
!= stat
->mode
) {
364 struct iattr attr
= {
365 .ia_valid
= ATTR_MODE
,
366 .ia_mode
= stat
->mode
,
368 inode_lock(newdentry
->d_inode
);
369 err
= notify_change(newdentry
, &attr
, NULL
);
370 inode_unlock(newdentry
->d_inode
);
375 if (S_ISDIR(stat
->mode
)) {
376 err
= ovl_set_opaque(newdentry
);
380 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
,
385 ovl_cleanup(wdir
, upper
);
387 err
= ovl_do_rename(wdir
, newdentry
, udir
, upper
, 0);
391 ovl_instantiate(dentry
, inode
, newdentry
);
398 unlock_rename(workdir
, upperdir
);
403 ovl_cleanup(wdir
, newdentry
);
407 static int ovl_create_or_link(struct dentry
*dentry
, int mode
, dev_t rdev
,
408 const char *link
, struct dentry
*hardlink
)
412 const struct cred
*old_cred
;
413 struct cred
*override_cred
;
414 struct kstat stat
= {
419 inode
= ovl_new_inode(dentry
->d_sb
, mode
, dentry
->d_fsdata
);
423 err
= ovl_copy_up(dentry
->d_parent
);
427 inode_init_owner(inode
, dentry
->d_parent
->d_inode
, mode
);
428 stat
.mode
= inode
->i_mode
;
430 old_cred
= ovl_override_creds(dentry
->d_sb
);
432 override_cred
= prepare_creds();
434 override_cred
->fsuid
= inode
->i_uid
;
435 override_cred
->fsgid
= inode
->i_gid
;
436 put_cred(override_creds(override_cred
));
437 put_cred(override_cred
);
439 if (!ovl_dentry_is_opaque(dentry
))
440 err
= ovl_create_upper(dentry
, inode
, &stat
, link
,
443 err
= ovl_create_over_whiteout(dentry
, inode
, &stat
,
446 revert_creds(old_cred
);
448 struct inode
*realinode
= d_inode(ovl_dentry_upper(dentry
));
450 WARN_ON(inode
->i_mode
!= realinode
->i_mode
);
451 WARN_ON(!uid_eq(inode
->i_uid
, realinode
->i_uid
));
452 WARN_ON(!gid_eq(inode
->i_gid
, realinode
->i_gid
));
461 static int ovl_create_object(struct dentry
*dentry
, int mode
, dev_t rdev
,
466 err
= ovl_want_write(dentry
);
468 err
= ovl_create_or_link(dentry
, mode
, rdev
, link
, NULL
);
469 ovl_drop_write(dentry
);
475 static int ovl_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
478 return ovl_create_object(dentry
, (mode
& 07777) | S_IFREG
, 0, NULL
);
481 static int ovl_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
483 return ovl_create_object(dentry
, (mode
& 07777) | S_IFDIR
, 0, NULL
);
486 static int ovl_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
489 /* Don't allow creation of "whiteout" on overlay */
490 if (S_ISCHR(mode
) && rdev
== WHITEOUT_DEV
)
493 return ovl_create_object(dentry
, mode
, rdev
, NULL
);
496 static int ovl_symlink(struct inode
*dir
, struct dentry
*dentry
,
499 return ovl_create_object(dentry
, S_IFLNK
, 0, link
);
502 static int ovl_link(struct dentry
*old
, struct inode
*newdir
,
506 struct dentry
*upper
;
508 err
= ovl_want_write(old
);
512 err
= ovl_copy_up(old
);
516 upper
= ovl_dentry_upper(old
);
517 err
= ovl_create_or_link(new, upper
->d_inode
->i_mode
, 0, NULL
, upper
);
525 static int ovl_remove_and_whiteout(struct dentry
*dentry
, bool is_dir
)
527 struct dentry
*workdir
= ovl_workdir(dentry
);
528 struct inode
*wdir
= workdir
->d_inode
;
529 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
530 struct inode
*udir
= upperdir
->d_inode
;
531 struct dentry
*whiteout
;
532 struct dentry
*upper
;
533 struct dentry
*opaquedir
= NULL
;
537 if (WARN_ON(!workdir
))
541 if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry
))) {
542 opaquedir
= ovl_check_empty_and_clear(dentry
);
543 err
= PTR_ERR(opaquedir
);
544 if (IS_ERR(opaquedir
))
550 * When removing an empty opaque directory, then it
551 * makes no sense to replace it with an exact replica of
552 * itself. But emptiness still needs to be checked.
554 err
= ovl_check_empty_dir(dentry
, &list
);
555 ovl_cache_free(&list
);
561 err
= ovl_lock_rename_workdir(workdir
, upperdir
);
565 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
567 err
= PTR_ERR(upper
);
572 if ((opaquedir
&& upper
!= opaquedir
) ||
573 (!opaquedir
&& ovl_dentry_upper(dentry
) &&
574 upper
!= ovl_dentry_upper(dentry
))) {
578 whiteout
= ovl_whiteout(workdir
, dentry
);
579 err
= PTR_ERR(whiteout
);
580 if (IS_ERR(whiteout
))
584 flags
= RENAME_EXCHANGE
;
586 err
= ovl_do_rename(wdir
, whiteout
, udir
, upper
, flags
);
590 ovl_cleanup(wdir
, upper
);
592 ovl_dentry_version_inc(dentry
->d_parent
);
599 unlock_rename(workdir
, upperdir
);
606 ovl_cleanup(wdir
, whiteout
);
610 static int ovl_remove_upper(struct dentry
*dentry
, bool is_dir
)
612 struct dentry
*upperdir
= ovl_dentry_upper(dentry
->d_parent
);
613 struct inode
*dir
= upperdir
->d_inode
;
614 struct dentry
*upper
;
617 inode_lock_nested(dir
, I_MUTEX_PARENT
);
618 upper
= lookup_one_len(dentry
->d_name
.name
, upperdir
,
620 err
= PTR_ERR(upper
);
625 if (upper
== ovl_dentry_upper(dentry
)) {
627 err
= vfs_rmdir(dir
, upper
);
629 err
= vfs_unlink(dir
, upper
, NULL
);
630 ovl_dentry_version_inc(dentry
->d_parent
);
635 * Keeping this dentry hashed would mean having to release
636 * upperpath/lowerpath, which could only be done if we are the
637 * sole user of this dentry. Too tricky... Just unhash for
648 static inline int ovl_check_sticky(struct dentry
*dentry
)
650 struct inode
*dir
= ovl_dentry_real(dentry
->d_parent
)->d_inode
;
651 struct inode
*inode
= ovl_dentry_real(dentry
)->d_inode
;
653 if (check_sticky(dir
, inode
))
659 static int ovl_do_remove(struct dentry
*dentry
, bool is_dir
)
661 enum ovl_path_type type
;
663 const struct cred
*old_cred
;
666 err
= ovl_check_sticky(dentry
);
670 err
= ovl_want_write(dentry
);
674 err
= ovl_copy_up(dentry
->d_parent
);
678 type
= ovl_path_type(dentry
);
680 old_cred
= ovl_override_creds(dentry
->d_sb
);
681 if (OVL_TYPE_PURE_UPPER(type
))
682 err
= ovl_remove_upper(dentry
, is_dir
);
684 err
= ovl_remove_and_whiteout(dentry
, is_dir
);
685 revert_creds(old_cred
);
687 ovl_drop_write(dentry
);
692 static int ovl_unlink(struct inode
*dir
, struct dentry
*dentry
)
694 return ovl_do_remove(dentry
, false);
697 static int ovl_rmdir(struct inode
*dir
, struct dentry
*dentry
)
699 return ovl_do_remove(dentry
, true);
702 static int ovl_rename2(struct inode
*olddir
, struct dentry
*old
,
703 struct inode
*newdir
, struct dentry
*new,
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
;
716 bool cleanup_whiteout
= false;
717 bool overwrite
= !(flags
& RENAME_EXCHANGE
);
718 bool is_dir
= d_is_dir(old
);
719 bool new_is_dir
= false;
720 struct dentry
*opaquedir
= NULL
;
721 const struct cred
*old_cred
= NULL
;
724 if (flags
& ~(RENAME_EXCHANGE
| RENAME_NOREPLACE
))
727 flags
&= ~RENAME_NOREPLACE
;
729 err
= ovl_check_sticky(old
);
733 /* Don't copy up directory trees */
734 old_type
= ovl_path_type(old
);
736 if (OVL_TYPE_MERGE_OR_LOWER(old_type
) && is_dir
)
740 err
= ovl_check_sticky(new);
747 new_type
= ovl_path_type(new);
749 if (!overwrite
&& OVL_TYPE_MERGE_OR_LOWER(new_type
) && new_is_dir
)
753 if (!OVL_TYPE_UPPER(new_type
) && !OVL_TYPE_UPPER(old_type
)) {
754 if (ovl_dentry_lower(old
)->d_inode
==
755 ovl_dentry_lower(new)->d_inode
)
758 if (OVL_TYPE_UPPER(new_type
) && OVL_TYPE_UPPER(old_type
)) {
759 if (ovl_dentry_upper(old
)->d_inode
==
760 ovl_dentry_upper(new)->d_inode
)
764 if (ovl_dentry_is_opaque(new))
765 new_type
= __OVL_PATH_UPPER
;
767 new_type
= __OVL_PATH_UPPER
| __OVL_PATH_PURE
;
770 err
= ovl_want_write(old
);
774 err
= ovl_copy_up(old
);
778 err
= ovl_copy_up(new->d_parent
);
782 err
= ovl_copy_up(new);
787 old_opaque
= !OVL_TYPE_PURE_UPPER(old_type
);
788 new_opaque
= !OVL_TYPE_PURE_UPPER(new_type
);
790 old_cred
= ovl_override_creds(old
->d_sb
);
792 if (overwrite
&& OVL_TYPE_MERGE_OR_LOWER(new_type
) && new_is_dir
) {
793 opaquedir
= ovl_check_empty_and_clear(new);
794 err
= PTR_ERR(opaquedir
);
795 if (IS_ERR(opaquedir
)) {
797 goto out_revert_creds
;
803 if (new->d_inode
|| !new_opaque
) {
804 /* Whiteout source */
805 flags
|= RENAME_WHITEOUT
;
807 /* Switch whiteouts */
808 flags
|= RENAME_EXCHANGE
;
810 } else if (is_dir
&& !new->d_inode
&& new_opaque
) {
811 flags
|= RENAME_EXCHANGE
;
812 cleanup_whiteout
= true;
816 old_upperdir
= ovl_dentry_upper(old
->d_parent
);
817 new_upperdir
= ovl_dentry_upper(new->d_parent
);
819 trap
= lock_rename(new_upperdir
, old_upperdir
);
822 olddentry
= lookup_one_len(old
->d_name
.name
, old_upperdir
,
824 err
= PTR_ERR(olddentry
);
825 if (IS_ERR(olddentry
))
829 if (olddentry
!= ovl_dentry_upper(old
))
832 newdentry
= lookup_one_len(new->d_name
.name
, new_upperdir
,
834 err
= PTR_ERR(newdentry
);
835 if (IS_ERR(newdentry
))
839 if (ovl_dentry_upper(new)) {
841 if (newdentry
!= opaquedir
)
844 if (newdentry
!= ovl_dentry_upper(new))
848 if (!d_is_negative(newdentry
) &&
849 (!new_opaque
|| !ovl_is_whiteout(newdentry
)))
853 if (olddentry
== trap
)
855 if (newdentry
== trap
)
858 if (is_dir
&& !old_opaque
&& new_opaque
) {
859 err
= ovl_set_opaque(olddentry
);
863 if (!overwrite
&& new_is_dir
&& old_opaque
&& !new_opaque
) {
864 err
= ovl_set_opaque(newdentry
);
869 if (old_opaque
|| new_opaque
) {
870 err
= ovl_do_rename(old_upperdir
->d_inode
, olddentry
,
871 new_upperdir
->d_inode
, newdentry
,
874 /* No debug for the plain case */
875 BUG_ON(flags
& ~RENAME_EXCHANGE
);
876 err
= vfs_rename(old_upperdir
->d_inode
, olddentry
,
877 new_upperdir
->d_inode
, newdentry
,
882 if (is_dir
&& !old_opaque
&& new_opaque
)
883 ovl_remove_opaque(olddentry
);
884 if (!overwrite
&& new_is_dir
&& old_opaque
&& !new_opaque
)
885 ovl_remove_opaque(newdentry
);
889 if (is_dir
&& old_opaque
&& !new_opaque
)
890 ovl_remove_opaque(olddentry
);
891 if (!overwrite
&& new_is_dir
&& !old_opaque
&& new_opaque
)
892 ovl_remove_opaque(newdentry
);
895 * Old dentry now lives in different location. Dentries in
896 * lowerstack are stale. We cannot drop them here because
897 * access to them is lockless. This could be only pure upper
898 * or opaque directory - numlower is zero. Or upper non-dir
899 * entry - its pureness is tracked by flag opaque.
901 if (old_opaque
!= new_opaque
) {
902 ovl_dentry_set_opaque(old
, new_opaque
);
904 ovl_dentry_set_opaque(new, old_opaque
);
907 if (cleanup_whiteout
)
908 ovl_cleanup(old_upperdir
->d_inode
, newdentry
);
910 ovl_dentry_version_inc(old
->d_parent
);
911 ovl_dentry_version_inc(new->d_parent
);
918 unlock_rename(new_upperdir
, old_upperdir
);
920 revert_creds(old_cred
);
928 const struct inode_operations ovl_dir_inode_operations
= {
929 .lookup
= ovl_lookup
,
931 .symlink
= ovl_symlink
,
932 .unlink
= ovl_unlink
,
934 .rename2
= ovl_rename2
,
936 .setattr
= ovl_setattr
,
937 .create
= ovl_create
,
939 .permission
= ovl_permission
,
940 .getattr
= ovl_dir_getattr
,
941 .setxattr
= ovl_setxattr
,
942 .getxattr
= ovl_getxattr
,
943 .listxattr
= ovl_listxattr
,
944 .removexattr
= ovl_removexattr
,
945 .get_acl
= ovl_get_acl
,
946 .update_time
= ovl_update_time
,