diff --git a/Documentation/filesystems/overlayfs.rst b/Documentation/filesystems/overlayfs.rst
index b86be7c6a9529190060e5282b42a047a758c7a60..587a939739290628f7c236443493f570c6df7040 100644
--- a/Documentation/filesystems/overlayfs.rst
+++ b/Documentation/filesystems/overlayfs.rst
@@ -102,8 +102,8 @@ but not all filesystems that are mountable by Linux have the features
needed for OverlayFS to work. The lower filesystem does not need to be
writable. The lower filesystem can even be another overlayfs. The upper
filesystem will normally be writable and if it is it must support the
-creation of trusted.* extended attributes, and must provide valid d_type in
-readdir responses, so NFS is not suitable.
+creation of trusted.* and/or user.* extended attributes, and must provide
+valid d_type in readdir responses, so NFS is not suitable.
A read-only overlay of two read-only filesystems may use any
filesystem type.
@@ -594,6 +594,15 @@ fresh one. In very limited cases where the user knows that the system has
not crashed and contents of upperdir are intact, The "volatile" directory
can be removed.
+
+User xattr
+----------
+
+The the "-o userxattr" mount option forces overlayfs to use the
+"user.overlay." xattr namespace instead of "trusted.overlay.". This is
+useful for unprivileged mounting of overlayfs.
+
+
Testsuite
---------
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1688ae7e3438053051806c440389d216265b15bc..d739e14c6814df6a38c004e96124a749b8948fe1 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -329,8 +329,14 @@ static const char *ovl_get_link(struct dentry *dentry,
bool ovl_is_private_xattr(struct super_block *sb, const char *name)
{
- return strncmp(name, OVL_XATTR_PREFIX,
- sizeof(OVL_XATTR_PREFIX) - 1) == 0;
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ if (ofs->config.userxattr)
+ return strncmp(name, OVL_XATTR_USER_PREFIX,
+ sizeof(OVL_XATTR_USER_PREFIX) - 1) == 0;
+ else
+ return strncmp(name, OVL_XATTR_TRUSTED_PREFIX,
+ sizeof(OVL_XATTR_TRUSTED_PREFIX) - 1) == 0;
}
int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
@@ -690,7 +696,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
* For the first, copy up case, the union nlink does not change, whether the
* operation succeeds or fails, but the upper inode nlink may change.
* Therefore, before copy up, we store the union nlink value relative to the
- * lower inode nlink in the index inode xattr trusted.overlay.nlink.
+ * lower inode nlink in the index inode xattr .overlay.nlink.
*
* For the second, upper hardlink case, the union nlink should be incremented
* or decremented IFF the operation succeeds, aligned with nlink change of the
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 79a971fe8b1316f1874a7ab7cf79d706d39706f5..b487e48c7fd4276d22caf17a56e75f5f298a8cdf 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -22,7 +22,9 @@ enum ovl_path_type {
#define OVL_TYPE_MERGE(type) ((type) & __OVL_PATH_MERGE)
#define OVL_TYPE_ORIGIN(type) ((type) & __OVL_PATH_ORIGIN)
-#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
+#define OVL_XATTR_NAMESPACE "overlay."
+#define OVL_XATTR_TRUSTED_PREFIX XATTR_TRUSTED_PREFIX OVL_XATTR_NAMESPACE
+#define OVL_XATTR_USER_PREFIX XATTR_USER_PREFIX OVL_XATTR_NAMESPACE
enum ovl_xattr {
OVL_XATTR_OPAQUE,
@@ -113,10 +115,10 @@ struct ovl_fh {
#define OVL_FH_FID_OFFSET (OVL_FH_WIRE_OFFSET + \
offsetof(struct ovl_fb, fid))
-extern const char *ovl_xattr_table[];
+extern const char *const ovl_xattr_table[][2];
static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
{
- return ovl_xattr_table[ox];
+ return ovl_xattr_table[ox][ofs->config.userxattr];
}
static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index b7a73ea147b8f6a2389eca78cbc00664a49f8c39..fbd5e27ce66bd3aad0c44e406ed943c016c1ea32 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -18,6 +18,7 @@ struct ovl_config {
bool nfs_export;
int xino;
bool metacopy;
+ bool userxattr;
bool ovl_volatile;
};
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 8cd6a45322fe124284cafe3e2664f56c917388f4..6366adf81fa316104e8810fcae00ed3160dd4656 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -418,6 +418,7 @@ enum {
OPT_UUID_ON,
OPT_UUID_OFF,
OPT_NFS_EXPORT_ON,
+ OPT_USERXATTR,
OPT_NFS_EXPORT_OFF,
OPT_XINO_ON,
OPT_XINO_OFF,
@@ -436,6 +437,7 @@ static const match_table_t ovl_tokens = {
{OPT_REDIRECT_DIR, "redirect_dir=%s"},
{OPT_INDEX_ON, "index=on"},
{OPT_INDEX_OFF, "index=off"},
+ {OPT_USERXATTR, "userxattr"},
{OPT_UUID_ON, "uuid=on"},
{OPT_UUID_OFF, "uuid=off"},
{OPT_NFS_EXPORT_ON, "nfs_export=on"},
@@ -602,6 +604,10 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
config->ovl_volatile = true;
break;
+ case OPT_USERXATTR:
+ config->userxattr = true;
+ break;
+
default:
pr_err("unrecognized mount option \"%s\" or missing value\n",
p);
@@ -705,6 +711,28 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
}
}
+
+ /* Resolve userxattr -> !redirect && !metacopy dependency */
+ if (config->userxattr) {
+ if (config->redirect_follow && redirect_opt) {
+ pr_err("conflicting options: userxattr,redirect_dir=%s\n",
+ config->redirect_mode);
+ return -EINVAL;
+ }
+ if (config->metacopy && metacopy_opt) {
+ pr_err("conflicting options: userxattr,metacopy=on\n");
+ return -EINVAL;
+ }
+ /*
+ * Silently disable default setting of redirect and metacopy.
+ * This shall be the default in the future as well: these
+ * options must be explicitly enabled if used together with
+ * userxattr.
+ */
+ config->redirect_dir = config->redirect_follow = false;
+ config->metacopy = false;
+ }
+
return 0;
}
@@ -1054,8 +1082,14 @@ ovl_posix_acl_default_xattr_handler = {
.set = ovl_posix_acl_xattr_set,
};
-static const struct xattr_handler ovl_own_xattr_handler = {
- .prefix = OVL_XATTR_PREFIX,
+static const struct xattr_handler ovl_own_trusted_xattr_handler = {
+ .prefix = OVL_XATTR_TRUSTED_PREFIX,
+ .get = ovl_own_xattr_get,
+ .set = ovl_own_xattr_set,
+};
+
+static const struct xattr_handler ovl_own_user_xattr_handler = {
+ .prefix = OVL_XATTR_USER_PREFIX,
.get = ovl_own_xattr_get,
.set = ovl_own_xattr_set,
};
@@ -1066,12 +1100,22 @@ static const struct xattr_handler ovl_other_xattr_handler = {
.set = ovl_other_xattr_set,
};
-static const struct xattr_handler *ovl_xattr_handlers[] = {
+static const struct xattr_handler *ovl_trusted_xattr_handlers[] = {
+#ifdef CONFIG_FS_POSIX_ACL
+ &ovl_posix_acl_access_xattr_handler,
+ &ovl_posix_acl_default_xattr_handler,
+#endif
+ &ovl_own_trusted_xattr_handler,
+ &ovl_other_xattr_handler,
+ NULL
+};
+
+static const struct xattr_handler *ovl_user_xattr_handlers[] = {
#ifdef CONFIG_FS_POSIX_ACL
&ovl_posix_acl_access_xattr_handler,
&ovl_posix_acl_default_xattr_handler,
#endif
- &ovl_own_xattr_handler,
+ &ovl_own_user_xattr_handler,
&ovl_other_xattr_handler,
NULL
};
@@ -1334,7 +1378,7 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
pr_warn("upper fs does not support RENAME_WHITEOUT.\n");
/*
- * Check if upper/work fs supports trusted.overlay.* xattr
+ * Check if upper/work fs supports (trusted|user).overlay.* xattr
*/
err = ovl_do_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
if (err) {
@@ -1473,10 +1517,10 @@ static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
/*
* Verify upper root is exclusively associated with index dir.
- * Older kernels stored upper fh in "trusted.overlay.origin"
+ * Older kernels stored upper fh in ".overlay.origin"
* xattr. If that xattr exists, verify that it is a match to
* upper dir file handle. In any case, verify or set xattr
- * "trusted.overlay.upper" to indicate that index may have
+ * ".overlay.upper" to indicate that index may have
* directory entries.
*/
if (ovl_check_origin_xattr(ofs, ofs->indexdir)) {
@@ -2014,7 +2058,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
sb->s_magic = OVERLAYFS_SUPER_MAGIC;
- sb->s_xattr = ovl_xattr_handlers;
+ sb->s_xattr = ofs->config.userxattr ? ovl_user_xattr_handlers :
+ ovl_trusted_xattr_handlers;
sb->s_fs_info = ofs;
sb->s_flags |= SB_POSIXACL;
sb->s_iflags |= SB_I_SKIP_SYNC;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index ced63c79e9ddcace5d22ee30edc8803c38f29516..e63e0587535f232fa1a8025e1eff7281c87fd675 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -585,9 +585,10 @@ bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
#define OVL_XATTR_METACOPY_POSTFIX "metacopy"
#define OVL_XATTR_TAB_ENTRY(x) \
- [x] = OVL_XATTR_PREFIX x ## _POSTFIX
+ [x] = { [false] = OVL_XATTR_TRUSTED_PREFIX x ## _POSTFIX, \
+ [true] = OVL_XATTR_USER_PREFIX x ## _POSTFIX }
-const char *ovl_xattr_table[] = {
+const char *const ovl_xattr_table[][2] = {
OVL_XATTR_TAB_ENTRY(OVL_XATTR_OPAQUE),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_REDIRECT),
OVL_XATTR_TAB_ENTRY(OVL_XATTR_ORIGIN),