staging/lustre: fix permission problem of setfacl

Setxattr does not check the permission when setting ACL xattrs. This
will cause security problem because any user can walk around
permission checking by changing ACL rules.
Signed-off-by: Li Xi <lixi@ddn.com>
Reviewed-on: http://review.whamcloud.com/9473
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4704Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/xattr.c

@@ -124,6 +124,11 @@ int ll_setxattr_common(struct inode *inode, const char *name,
 	if (rc)
 		return rc;
 
+	if ((xattr_type == XATTR_ACL_ACCESS_T ||
+	     xattr_type == XATTR_ACL_DEFAULT_T) &&
+	    !inode_owner_or_capable(inode))
+		return -EPERM;
+
 	/* b10667: ignore lustre special xattr for now */
 	if ((xattr_type == XATTR_TRUSTED_T && strcmp(name, "trusted.lov") == 0) ||
 	    (xattr_type == XATTR_LUSTRE_T && strcmp(name, "lustre.lov") == 0))