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.
10 #include <uapi/linux/magic.h>
12 #include <linux/namei.h>
13 #include <linux/xattr.h>
14 #include <linux/mount.h>
15 #include <linux/parser.h>
16 #include <linux/module.h>
17 #include <linux/statfs.h>
18 #include <linux/seq_file.h>
19 #include <linux/posix_acl_xattr.h>
20 #include "overlayfs.h"
21 #include "ovl_entry.h"
23 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
24 MODULE_DESCRIPTION("Overlay filesystem");
25 MODULE_LICENSE("GPL");
30 #define OVL_MAX_STACK 500
32 static bool ovl_redirect_dir_def
= IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR
);
33 module_param_named(redirect_dir
, ovl_redirect_dir_def
, bool, 0644);
34 MODULE_PARM_DESC(ovl_redirect_dir_def
,
35 "Default to on or off for the redirect_dir feature");
37 static bool ovl_index_def
= IS_ENABLED(CONFIG_OVERLAY_FS_INDEX
);
38 module_param_named(index
, ovl_index_def
, bool, 0644);
39 MODULE_PARM_DESC(ovl_index_def
,
40 "Default to on or off for the inodes index feature");
42 static void ovl_dentry_release(struct dentry
*dentry
)
44 struct ovl_entry
*oe
= dentry
->d_fsdata
;
49 for (i
= 0; i
< oe
->numlower
; i
++)
50 dput(oe
->lowerstack
[i
].dentry
);
55 static int ovl_check_append_only(struct inode
*inode
, int flag
)
58 * This test was moot in vfs may_open() because overlay inode does
59 * not have the S_APPEND flag, so re-check on real upper inode
61 if (IS_APPEND(inode
)) {
62 if ((flag
& O_ACCMODE
) != O_RDONLY
&& !(flag
& O_APPEND
))
71 static struct dentry
*ovl_d_real(struct dentry
*dentry
,
72 const struct inode
*inode
,
73 unsigned int open_flags
)
78 if (!d_is_reg(dentry
)) {
79 if (!inode
|| inode
== d_inode(dentry
))
84 if (d_is_negative(dentry
))
88 err
= ovl_open_maybe_copy_up(dentry
, open_flags
);
93 real
= ovl_dentry_upper(dentry
);
94 if (real
&& (!inode
|| inode
== d_inode(real
))) {
96 err
= ovl_check_append_only(d_inode(real
), open_flags
);
103 real
= ovl_dentry_lower(dentry
);
107 /* Handle recursion */
108 real
= d_real(real
, inode
, open_flags
);
110 if (!inode
|| inode
== d_inode(real
))
113 WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry
,
114 inode
? inode
->i_sb
->s_id
: "NULL", inode
? inode
->i_ino
: 0);
118 static int ovl_dentry_revalidate(struct dentry
*dentry
, unsigned int flags
)
120 struct ovl_entry
*oe
= dentry
->d_fsdata
;
124 for (i
= 0; i
< oe
->numlower
; i
++) {
125 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
127 if (d
->d_flags
& DCACHE_OP_REVALIDATE
) {
128 ret
= d
->d_op
->d_revalidate(d
, flags
);
132 if (!(flags
& LOOKUP_RCU
))
141 static int ovl_dentry_weak_revalidate(struct dentry
*dentry
, unsigned int flags
)
143 struct ovl_entry
*oe
= dentry
->d_fsdata
;
147 for (i
= 0; i
< oe
->numlower
; i
++) {
148 struct dentry
*d
= oe
->lowerstack
[i
].dentry
;
150 if (d
->d_flags
& DCACHE_OP_WEAK_REVALIDATE
) {
151 ret
= d
->d_op
->d_weak_revalidate(d
, flags
);
159 static const struct dentry_operations ovl_dentry_operations
= {
160 .d_release
= ovl_dentry_release
,
161 .d_real
= ovl_d_real
,
164 static const struct dentry_operations ovl_reval_dentry_operations
= {
165 .d_release
= ovl_dentry_release
,
166 .d_real
= ovl_d_real
,
167 .d_revalidate
= ovl_dentry_revalidate
,
168 .d_weak_revalidate
= ovl_dentry_weak_revalidate
,
171 static struct kmem_cache
*ovl_inode_cachep
;
173 static struct inode
*ovl_alloc_inode(struct super_block
*sb
)
175 struct ovl_inode
*oi
= kmem_cache_alloc(ovl_inode_cachep
, GFP_KERNEL
);
181 oi
->__upperdentry
= NULL
;
183 mutex_init(&oi
->lock
);
185 return &oi
->vfs_inode
;
188 static void ovl_i_callback(struct rcu_head
*head
)
190 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
192 kmem_cache_free(ovl_inode_cachep
, OVL_I(inode
));
195 static void ovl_destroy_inode(struct inode
*inode
)
197 struct ovl_inode
*oi
= OVL_I(inode
);
199 dput(oi
->__upperdentry
);
201 mutex_destroy(&oi
->lock
);
203 call_rcu(&inode
->i_rcu
, ovl_i_callback
);
206 static void ovl_put_super(struct super_block
*sb
)
208 struct ovl_fs
*ufs
= sb
->s_fs_info
;
213 ovl_inuse_unlock(ufs
->workbasedir
);
214 dput(ufs
->workbasedir
);
216 ovl_inuse_unlock(ufs
->upper_mnt
->mnt_root
);
217 mntput(ufs
->upper_mnt
);
218 for (i
= 0; i
< ufs
->numlower
; i
++)
219 mntput(ufs
->lower_mnt
[i
]);
220 kfree(ufs
->lower_mnt
);
222 kfree(ufs
->config
.lowerdir
);
223 kfree(ufs
->config
.upperdir
);
224 kfree(ufs
->config
.workdir
);
225 put_cred(ufs
->creator_cred
);
229 static int ovl_sync_fs(struct super_block
*sb
, int wait
)
231 struct ovl_fs
*ufs
= sb
->s_fs_info
;
232 struct super_block
*upper_sb
;
237 upper_sb
= ufs
->upper_mnt
->mnt_sb
;
238 if (!upper_sb
->s_op
->sync_fs
)
241 /* real inodes have already been synced by sync_filesystem(ovl_sb) */
242 down_read(&upper_sb
->s_umount
);
243 ret
= upper_sb
->s_op
->sync_fs(upper_sb
, wait
);
244 up_read(&upper_sb
->s_umount
);
250 * @sb: The overlayfs super block
251 * @buf: The struct kstatfs to fill in with stats
253 * Get the filesystem statistics. As writes always target the upper layer
254 * filesystem pass the statfs to the upper filesystem (if it exists)
256 static int ovl_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
258 struct ovl_fs
*ofs
= dentry
->d_sb
->s_fs_info
;
259 struct dentry
*root_dentry
= dentry
->d_sb
->s_root
;
263 ovl_path_real(root_dentry
, &path
);
265 err
= vfs_statfs(&path
, buf
);
267 buf
->f_namelen
= ofs
->namelen
;
268 buf
->f_type
= OVERLAYFS_SUPER_MAGIC
;
274 /* Will this overlay be forced to mount/remount ro? */
275 static bool ovl_force_readonly(struct ovl_fs
*ufs
)
277 return (!ufs
->upper_mnt
|| !ufs
->workdir
);
283 * Prints the mount options for a given superblock.
284 * Returns zero; does not fail.
286 static int ovl_show_options(struct seq_file
*m
, struct dentry
*dentry
)
288 struct super_block
*sb
= dentry
->d_sb
;
289 struct ovl_fs
*ufs
= sb
->s_fs_info
;
291 seq_show_option(m
, "lowerdir", ufs
->config
.lowerdir
);
292 if (ufs
->config
.upperdir
) {
293 seq_show_option(m
, "upperdir", ufs
->config
.upperdir
);
294 seq_show_option(m
, "workdir", ufs
->config
.workdir
);
296 if (ufs
->config
.default_permissions
)
297 seq_puts(m
, ",default_permissions");
298 if (ufs
->config
.redirect_dir
!= ovl_redirect_dir_def
)
299 seq_printf(m
, ",redirect_dir=%s",
300 ufs
->config
.redirect_dir
? "on" : "off");
301 if (ufs
->config
.index
!= ovl_index_def
)
302 seq_printf(m
, ",index=%s",
303 ufs
->config
.index
? "on" : "off");
307 static int ovl_remount(struct super_block
*sb
, int *flags
, char *data
)
309 struct ovl_fs
*ufs
= sb
->s_fs_info
;
311 if (!(*flags
& MS_RDONLY
) && ovl_force_readonly(ufs
))
317 static const struct super_operations ovl_super_operations
= {
318 .alloc_inode
= ovl_alloc_inode
,
319 .destroy_inode
= ovl_destroy_inode
,
320 .drop_inode
= generic_delete_inode
,
321 .put_super
= ovl_put_super
,
322 .sync_fs
= ovl_sync_fs
,
323 .statfs
= ovl_statfs
,
324 .show_options
= ovl_show_options
,
325 .remount_fs
= ovl_remount
,
332 OPT_DEFAULT_PERMISSIONS
,
334 OPT_REDIRECT_DIR_OFF
,
340 static const match_table_t ovl_tokens
= {
341 {OPT_LOWERDIR
, "lowerdir=%s"},
342 {OPT_UPPERDIR
, "upperdir=%s"},
343 {OPT_WORKDIR
, "workdir=%s"},
344 {OPT_DEFAULT_PERMISSIONS
, "default_permissions"},
345 {OPT_REDIRECT_DIR_ON
, "redirect_dir=on"},
346 {OPT_REDIRECT_DIR_OFF
, "redirect_dir=off"},
347 {OPT_INDEX_ON
, "index=on"},
348 {OPT_INDEX_OFF
, "index=off"},
352 static char *ovl_next_opt(char **s
)
360 for (p
= sbegin
; *p
; p
++) {
365 } else if (*p
== ',') {
375 static int ovl_parse_opt(char *opt
, struct ovl_config
*config
)
379 while ((p
= ovl_next_opt(&opt
)) != NULL
) {
381 substring_t args
[MAX_OPT_ARGS
];
386 token
= match_token(p
, ovl_tokens
, args
);
389 kfree(config
->upperdir
);
390 config
->upperdir
= match_strdup(&args
[0]);
391 if (!config
->upperdir
)
396 kfree(config
->lowerdir
);
397 config
->lowerdir
= match_strdup(&args
[0]);
398 if (!config
->lowerdir
)
403 kfree(config
->workdir
);
404 config
->workdir
= match_strdup(&args
[0]);
405 if (!config
->workdir
)
409 case OPT_DEFAULT_PERMISSIONS
:
410 config
->default_permissions
= true;
413 case OPT_REDIRECT_DIR_ON
:
414 config
->redirect_dir
= true;
417 case OPT_REDIRECT_DIR_OFF
:
418 config
->redirect_dir
= false;
422 config
->index
= true;
426 config
->index
= false;
430 pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p
);
435 /* Workdir is useless in non-upper mount */
436 if (!config
->upperdir
&& config
->workdir
) {
437 pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
439 kfree(config
->workdir
);
440 config
->workdir
= NULL
;
446 #define OVL_WORKDIR_NAME "work"
447 #define OVL_INDEXDIR_NAME "index"
449 static struct dentry
*ovl_workdir_create(struct super_block
*sb
,
451 struct dentry
*dentry
,
452 const char *name
, bool persist
)
454 struct inode
*dir
= dentry
->d_inode
;
455 struct vfsmount
*mnt
= ufs
->upper_mnt
;
458 bool retried
= false;
461 err
= mnt_want_write(mnt
);
465 inode_lock_nested(dir
, I_MUTEX_PARENT
);
469 work
= lookup_one_len(name
, dentry
, strlen(name
));
472 struct iattr attr
= {
473 .ia_valid
= ATTR_MODE
,
474 .ia_mode
= S_IFDIR
| 0,
486 ovl_workdir_cleanup(dir
, mnt
, work
, 0);
491 err
= ovl_create_real(dir
, work
,
492 &(struct cattr
){.mode
= S_IFDIR
| 0},
498 * Try to remove POSIX ACL xattrs from workdir. We are good if:
500 * a) success (there was a POSIX ACL xattr and was removed)
501 * b) -ENODATA (there was no POSIX ACL xattr)
502 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
504 * There are various other error values that could effectively
505 * mean that the xattr doesn't exist (e.g. -ERANGE is returned
506 * if the xattr name is too long), but the set of filesystems
507 * allowed as upper are limited to "normal" ones, where checking
508 * for the above two errors is sufficient.
510 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_DEFAULT
);
511 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
514 err
= vfs_removexattr(work
, XATTR_NAME_POSIX_ACL_ACCESS
);
515 if (err
&& err
!= -ENODATA
&& err
!= -EOPNOTSUPP
)
518 /* Clear any inherited mode bits */
519 inode_lock(work
->d_inode
);
520 err
= notify_change(work
, &attr
, NULL
);
521 inode_unlock(work
->d_inode
);
538 pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
539 ufs
->config
.workdir
, name
, -err
);
540 sb
->s_flags
|= MS_RDONLY
;
545 static void ovl_unescape(char *s
)
558 static int ovl_mount_dir_noesc(const char *name
, struct path
*path
)
563 pr_err("overlayfs: empty lowerdir\n");
566 err
= kern_path(name
, LOOKUP_FOLLOW
, path
);
568 pr_err("overlayfs: failed to resolve '%s': %i\n", name
, err
);
572 if (ovl_dentry_weird(path
->dentry
)) {
573 pr_err("overlayfs: filesystem on '%s' not supported\n", name
);
576 if (!d_is_dir(path
->dentry
)) {
577 pr_err("overlayfs: '%s' not a directory\n", name
);
588 static int ovl_mount_dir(const char *name
, struct path
*path
)
591 char *tmp
= kstrdup(name
, GFP_KERNEL
);
595 err
= ovl_mount_dir_noesc(tmp
, path
);
598 if (ovl_dentry_remote(path
->dentry
)) {
599 pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
609 static int ovl_check_namelen(struct path
*path
, struct ovl_fs
*ofs
,
612 struct kstatfs statfs
;
613 int err
= vfs_statfs(path
, &statfs
);
616 pr_err("overlayfs: statfs failed on '%s'\n", name
);
618 ofs
->namelen
= max(ofs
->namelen
, statfs
.f_namelen
);
623 static int ovl_lower_dir(const char *name
, struct path
*path
,
624 struct ovl_fs
*ofs
, int *stack_depth
, bool *remote
)
628 err
= ovl_mount_dir_noesc(name
, path
);
632 err
= ovl_check_namelen(path
, ofs
, name
);
636 *stack_depth
= max(*stack_depth
, path
->mnt
->mnt_sb
->s_stack_depth
);
638 if (ovl_dentry_remote(path
->dentry
))
642 * The inodes index feature needs to encode and decode file
643 * handles, so it requires that all layers support them.
645 if (ofs
->config
.index
&& !ovl_can_decode_fh(path
->dentry
->d_sb
)) {
646 ofs
->config
.index
= false;
647 pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off.\n", name
);
658 /* Workdir should not be subdir of upperdir and vice versa */
659 static bool ovl_workdir_ok(struct dentry
*workdir
, struct dentry
*upperdir
)
663 if (workdir
!= upperdir
) {
664 ok
= (lock_rename(workdir
, upperdir
) == NULL
);
665 unlock_rename(workdir
, upperdir
);
670 static unsigned int ovl_split_lowerdirs(char *str
)
672 unsigned int ctr
= 1;
675 for (s
= d
= str
;; s
++, d
++) {
678 } else if (*s
== ':') {
690 static int __maybe_unused
691 ovl_posix_acl_xattr_get(const struct xattr_handler
*handler
,
692 struct dentry
*dentry
, struct inode
*inode
,
693 const char *name
, void *buffer
, size_t size
)
695 return ovl_xattr_get(dentry
, inode
, handler
->name
, buffer
, size
);
698 static int __maybe_unused
699 ovl_posix_acl_xattr_set(const struct xattr_handler
*handler
,
700 struct dentry
*dentry
, struct inode
*inode
,
701 const char *name
, const void *value
,
702 size_t size
, int flags
)
704 struct dentry
*workdir
= ovl_workdir(dentry
);
705 struct inode
*realinode
= ovl_inode_real(inode
);
706 struct posix_acl
*acl
= NULL
;
709 /* Check that everything is OK before copy-up */
711 acl
= posix_acl_from_xattr(&init_user_ns
, value
, size
);
716 if (!IS_POSIXACL(d_inode(workdir
)))
717 goto out_acl_release
;
718 if (!realinode
->i_op
->set_acl
)
719 goto out_acl_release
;
720 if (handler
->flags
== ACL_TYPE_DEFAULT
&& !S_ISDIR(inode
->i_mode
)) {
721 err
= acl
? -EACCES
: 0;
722 goto out_acl_release
;
725 if (!inode_owner_or_capable(inode
))
726 goto out_acl_release
;
728 posix_acl_release(acl
);
731 * Check if sgid bit needs to be cleared (actual setacl operation will
732 * be done with mounter's capabilities and so that won't do it for us).
734 if (unlikely(inode
->i_mode
& S_ISGID
) &&
735 handler
->flags
== ACL_TYPE_ACCESS
&&
736 !in_group_p(inode
->i_gid
) &&
737 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
)) {
738 struct iattr iattr
= { .ia_valid
= ATTR_KILL_SGID
};
740 err
= ovl_setattr(dentry
, &iattr
);
745 err
= ovl_xattr_set(dentry
, inode
, handler
->name
, value
, size
, flags
);
747 ovl_copyattr(ovl_inode_real(inode
), inode
);
752 posix_acl_release(acl
);
756 static int ovl_own_xattr_get(const struct xattr_handler
*handler
,
757 struct dentry
*dentry
, struct inode
*inode
,
758 const char *name
, void *buffer
, size_t size
)
763 static int ovl_own_xattr_set(const struct xattr_handler
*handler
,
764 struct dentry
*dentry
, struct inode
*inode
,
765 const char *name
, const void *value
,
766 size_t size
, int flags
)
771 static int ovl_other_xattr_get(const struct xattr_handler
*handler
,
772 struct dentry
*dentry
, struct inode
*inode
,
773 const char *name
, void *buffer
, size_t size
)
775 return ovl_xattr_get(dentry
, inode
, name
, buffer
, size
);
778 static int ovl_other_xattr_set(const struct xattr_handler
*handler
,
779 struct dentry
*dentry
, struct inode
*inode
,
780 const char *name
, const void *value
,
781 size_t size
, int flags
)
783 return ovl_xattr_set(dentry
, inode
, name
, value
, size
, flags
);
786 static const struct xattr_handler __maybe_unused
787 ovl_posix_acl_access_xattr_handler
= {
788 .name
= XATTR_NAME_POSIX_ACL_ACCESS
,
789 .flags
= ACL_TYPE_ACCESS
,
790 .get
= ovl_posix_acl_xattr_get
,
791 .set
= ovl_posix_acl_xattr_set
,
794 static const struct xattr_handler __maybe_unused
795 ovl_posix_acl_default_xattr_handler
= {
796 .name
= XATTR_NAME_POSIX_ACL_DEFAULT
,
797 .flags
= ACL_TYPE_DEFAULT
,
798 .get
= ovl_posix_acl_xattr_get
,
799 .set
= ovl_posix_acl_xattr_set
,
802 static const struct xattr_handler ovl_own_xattr_handler
= {
803 .prefix
= OVL_XATTR_PREFIX
,
804 .get
= ovl_own_xattr_get
,
805 .set
= ovl_own_xattr_set
,
808 static const struct xattr_handler ovl_other_xattr_handler
= {
809 .prefix
= "", /* catch all */
810 .get
= ovl_other_xattr_get
,
811 .set
= ovl_other_xattr_set
,
814 static const struct xattr_handler
*ovl_xattr_handlers
[] = {
815 #ifdef CONFIG_FS_POSIX_ACL
816 &ovl_posix_acl_access_xattr_handler
,
817 &ovl_posix_acl_default_xattr_handler
,
819 &ovl_own_xattr_handler
,
820 &ovl_other_xattr_handler
,
824 static int ovl_fill_super(struct super_block
*sb
, void *data
, int silent
)
826 struct path upperpath
= { };
827 struct path workpath
= { };
828 struct dentry
*root_dentry
;
829 struct ovl_entry
*oe
;
831 struct path
*stack
= NULL
;
834 unsigned int numlower
;
835 unsigned int stacklen
= 0;
842 ufs
= kzalloc(sizeof(struct ovl_fs
), GFP_KERNEL
);
846 ufs
->config
.redirect_dir
= ovl_redirect_dir_def
;
847 ufs
->config
.index
= ovl_index_def
;
848 err
= ovl_parse_opt((char *) data
, &ufs
->config
);
850 goto out_free_config
;
853 if (!ufs
->config
.lowerdir
) {
855 pr_err("overlayfs: missing 'lowerdir'\n");
856 goto out_free_config
;
859 sb
->s_stack_depth
= 0;
860 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
861 if (ufs
->config
.upperdir
) {
862 if (!ufs
->config
.workdir
) {
863 pr_err("overlayfs: missing 'workdir'\n");
864 goto out_free_config
;
867 err
= ovl_mount_dir(ufs
->config
.upperdir
, &upperpath
);
869 goto out_free_config
;
871 /* Upper fs should not be r/o */
872 if (upperpath
.mnt
->mnt_sb
->s_flags
& MS_RDONLY
) {
873 pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
875 goto out_put_upperpath
;
878 err
= ovl_check_namelen(&upperpath
, ufs
, ufs
->config
.upperdir
);
880 goto out_put_upperpath
;
883 if (!ovl_inuse_trylock(upperpath
.dentry
)) {
884 pr_err("overlayfs: upperdir is in-use by another mount\n");
885 goto out_put_upperpath
;
888 err
= ovl_mount_dir(ufs
->config
.workdir
, &workpath
);
890 goto out_unlock_upperdentry
;
893 if (upperpath
.mnt
!= workpath
.mnt
) {
894 pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
895 goto out_put_workpath
;
897 if (!ovl_workdir_ok(workpath
.dentry
, upperpath
.dentry
)) {
898 pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
899 goto out_put_workpath
;
903 if (!ovl_inuse_trylock(workpath
.dentry
)) {
904 pr_err("overlayfs: workdir is in-use by another mount\n");
905 goto out_put_workpath
;
908 ufs
->workbasedir
= workpath
.dentry
;
909 sb
->s_stack_depth
= upperpath
.mnt
->mnt_sb
->s_stack_depth
;
912 lowertmp
= kstrdup(ufs
->config
.lowerdir
, GFP_KERNEL
);
914 goto out_unlock_workdentry
;
917 stacklen
= ovl_split_lowerdirs(lowertmp
);
918 if (stacklen
> OVL_MAX_STACK
) {
919 pr_err("overlayfs: too many lower directories, limit is %d\n",
921 goto out_free_lowertmp
;
922 } else if (!ufs
->config
.upperdir
&& stacklen
== 1) {
923 pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
924 goto out_free_lowertmp
;
928 stack
= kcalloc(stacklen
, sizeof(struct path
), GFP_KERNEL
);
930 goto out_free_lowertmp
;
934 for (numlower
= 0; numlower
< stacklen
; numlower
++) {
935 err
= ovl_lower_dir(lower
, &stack
[numlower
], ufs
,
936 &sb
->s_stack_depth
, &remote
);
938 goto out_put_lowerpath
;
940 lower
= strchr(lower
, '\0') + 1;
945 if (sb
->s_stack_depth
> FILESYSTEM_MAX_STACK_DEPTH
) {
946 pr_err("overlayfs: maximum fs stacking depth exceeded\n");
947 goto out_put_lowerpath
;
950 if (ufs
->config
.upperdir
) {
951 ufs
->upper_mnt
= clone_private_mount(&upperpath
);
952 err
= PTR_ERR(ufs
->upper_mnt
);
953 if (IS_ERR(ufs
->upper_mnt
)) {
954 pr_err("overlayfs: failed to clone upperpath\n");
955 goto out_put_lowerpath
;
958 /* Don't inherit atime flags */
959 ufs
->upper_mnt
->mnt_flags
&= ~(MNT_NOATIME
| MNT_NODIRATIME
| MNT_RELATIME
);
961 sb
->s_time_gran
= ufs
->upper_mnt
->mnt_sb
->s_time_gran
;
963 ufs
->workdir
= ovl_workdir_create(sb
, ufs
, workpath
.dentry
,
964 OVL_WORKDIR_NAME
, false);
966 * Upper should support d_type, else whiteouts are visible.
967 * Given workdir and upper are on same fs, we can do
968 * iterate_dir() on workdir. This check requires successful
969 * creation of workdir in previous step.
974 err
= ovl_check_d_type_supported(&workpath
);
976 goto out_put_workdir
;
979 * We allowed this configuration and don't want to
980 * break users over kernel upgrade. So warn instead
984 pr_warn("overlayfs: upper fs needs to support d_type.\n");
986 /* Check if upper/work fs supports O_TMPFILE */
987 temp
= ovl_do_tmpfile(ufs
->workdir
, S_IFREG
| 0);
988 ufs
->tmpfile
= !IS_ERR(temp
);
992 pr_warn("overlayfs: upper fs does not support tmpfile.\n");
995 * Check if upper/work fs supports trusted.overlay.*
998 err
= ovl_do_setxattr(ufs
->workdir
, OVL_XATTR_OPAQUE
,
1001 ufs
->noxattr
= true;
1002 pr_warn("overlayfs: upper fs does not support xattr.\n");
1004 vfs_removexattr(ufs
->workdir
, OVL_XATTR_OPAQUE
);
1007 /* Check if upper/work fs supports file handles */
1008 if (ufs
->config
.index
&&
1009 !ovl_can_decode_fh(ufs
->workdir
->d_sb
)) {
1010 ufs
->config
.index
= false;
1011 pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
1017 ufs
->lower_mnt
= kcalloc(numlower
, sizeof(struct vfsmount
*), GFP_KERNEL
);
1018 if (ufs
->lower_mnt
== NULL
)
1019 goto out_put_workdir
;
1020 for (i
= 0; i
< numlower
; i
++) {
1021 struct vfsmount
*mnt
= clone_private_mount(&stack
[i
]);
1025 pr_err("overlayfs: failed to clone lowerpath\n");
1026 goto out_put_lower_mnt
;
1029 * Make lower_mnt R/O. That way fchmod/fchown on lower file
1030 * will fail instead of modifying lower fs.
1032 mnt
->mnt_flags
|= MNT_READONLY
| MNT_NOATIME
;
1034 ufs
->lower_mnt
[ufs
->numlower
] = mnt
;
1037 /* Check if all lower layers are on same sb */
1039 ufs
->same_sb
= mnt
->mnt_sb
;
1040 else if (ufs
->same_sb
!= mnt
->mnt_sb
)
1041 ufs
->same_sb
= NULL
;
1044 /* If the upper fs is nonexistent, we mark overlayfs r/o too */
1045 if (!ufs
->upper_mnt
)
1046 sb
->s_flags
|= MS_RDONLY
;
1047 else if (ufs
->upper_mnt
->mnt_sb
!= ufs
->same_sb
)
1048 ufs
->same_sb
= NULL
;
1050 if (!(ovl_force_readonly(ufs
)) && ufs
->config
.index
) {
1051 /* Verify lower root is upper root origin */
1052 err
= ovl_verify_origin(upperpath
.dentry
, ufs
->lower_mnt
[0],
1053 stack
[0].dentry
, false, true);
1055 pr_err("overlayfs: failed to verify upper root origin\n");
1056 goto out_put_lower_mnt
;
1059 ufs
->indexdir
= ovl_workdir_create(sb
, ufs
, workpath
.dentry
,
1060 OVL_INDEXDIR_NAME
, true);
1061 if (ufs
->indexdir
) {
1062 /* Verify upper root is index dir origin */
1063 err
= ovl_verify_origin(ufs
->indexdir
, ufs
->upper_mnt
,
1064 upperpath
.dentry
, true, true);
1066 pr_err("overlayfs: failed to verify index dir origin\n");
1068 /* Cleanup bad/stale/orphan index entries */
1070 err
= ovl_indexdir_cleanup(ufs
->indexdir
,
1074 if (err
|| !ufs
->indexdir
)
1075 pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
1077 goto out_put_indexdir
;
1080 /* Show index=off/on in /proc/mounts for any of the reasons above */
1082 ufs
->config
.index
= false;
1085 sb
->s_d_op
= &ovl_reval_dentry_operations
;
1087 sb
->s_d_op
= &ovl_dentry_operations
;
1090 ufs
->creator_cred
= cred
= prepare_creds();
1092 goto out_put_indexdir
;
1094 /* Never override disk quota limits or use reserved space */
1095 cap_lower(cred
->cap_effective
, CAP_SYS_RESOURCE
);
1098 oe
= ovl_alloc_entry(numlower
);
1102 sb
->s_magic
= OVERLAYFS_SUPER_MAGIC
;
1103 sb
->s_op
= &ovl_super_operations
;
1104 sb
->s_xattr
= ovl_xattr_handlers
;
1105 sb
->s_fs_info
= ufs
;
1106 sb
->s_flags
|= MS_POSIXACL
| MS_NOREMOTELOCK
;
1108 root_dentry
= d_make_root(ovl_new_inode(sb
, S_IFDIR
, 0));
1112 mntput(upperpath
.mnt
);
1113 for (i
= 0; i
< numlower
; i
++)
1114 mntput(stack
[i
].mnt
);
1115 mntput(workpath
.mnt
);
1118 if (upperpath
.dentry
) {
1119 oe
->has_upper
= true;
1120 if (ovl_is_impuredir(upperpath
.dentry
))
1121 ovl_set_flag(OVL_IMPURE
, d_inode(root_dentry
));
1123 for (i
= 0; i
< numlower
; i
++) {
1124 oe
->lowerstack
[i
].dentry
= stack
[i
].dentry
;
1125 oe
->lowerstack
[i
].mnt
= ufs
->lower_mnt
[i
];
1129 root_dentry
->d_fsdata
= oe
;
1131 ovl_inode_init(d_inode(root_dentry
), upperpath
.dentry
,
1132 ovl_dentry_lower(root_dentry
));
1134 sb
->s_root
= root_dentry
;
1141 put_cred(ufs
->creator_cred
);
1143 dput(ufs
->indexdir
);
1145 for (i
= 0; i
< ufs
->numlower
; i
++)
1146 mntput(ufs
->lower_mnt
[i
]);
1147 kfree(ufs
->lower_mnt
);
1150 mntput(ufs
->upper_mnt
);
1152 for (i
= 0; i
< numlower
; i
++)
1153 path_put(&stack
[i
]);
1157 out_unlock_workdentry
:
1158 ovl_inuse_unlock(workpath
.dentry
);
1160 path_put(&workpath
);
1161 out_unlock_upperdentry
:
1162 ovl_inuse_unlock(upperpath
.dentry
);
1164 path_put(&upperpath
);
1166 kfree(ufs
->config
.lowerdir
);
1167 kfree(ufs
->config
.upperdir
);
1168 kfree(ufs
->config
.workdir
);
1174 static struct dentry
*ovl_mount(struct file_system_type
*fs_type
, int flags
,
1175 const char *dev_name
, void *raw_data
)
1177 return mount_nodev(fs_type
, flags
, raw_data
, ovl_fill_super
);
1180 static struct file_system_type ovl_fs_type
= {
1181 .owner
= THIS_MODULE
,
1184 .kill_sb
= kill_anon_super
,
1186 MODULE_ALIAS_FS("overlay");
1188 static void ovl_inode_init_once(void *foo
)
1190 struct ovl_inode
*oi
= foo
;
1192 inode_init_once(&oi
->vfs_inode
);
1195 static int __init
ovl_init(void)
1199 ovl_inode_cachep
= kmem_cache_create("ovl_inode",
1200 sizeof(struct ovl_inode
), 0,
1201 (SLAB_RECLAIM_ACCOUNT
|
1202 SLAB_MEM_SPREAD
|SLAB_ACCOUNT
),
1203 ovl_inode_init_once
);
1204 if (ovl_inode_cachep
== NULL
)
1207 err
= register_filesystem(&ovl_fs_type
);
1209 kmem_cache_destroy(ovl_inode_cachep
);
1214 static void __exit
ovl_exit(void)
1216 unregister_filesystem(&ovl_fs_type
);
1219 * Make sure all delayed rcu free inodes are flushed before we
1223 kmem_cache_destroy(ovl_inode_cachep
);
1227 module_init(ovl_init
);
1228 module_exit(ovl_exit
);