netfilter: xt_owner: bail out with EINVAL in case of unsupported flags

Reject flags that are not supported with EINVAL.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/uapi/linux/netfilter/xt_owner.h

@@ -11,6 +11,11 @@ enum {
 	XT_OWNER_SUPPL_GROUPS = 1 << 3,
 };
 
+#define XT_OWNER_MASK	(XT_OWNER_UID | 	\
+			 XT_OWNER_GID | 	\
+			 XT_OWNER_SOCKET |	\
+			 XT_OWNER_SUPPL_GROUPS)
+
 struct xt_owner_match_info {
 	__u32 uid_min, uid_max;
 	__u32 gid_min, gid_max;

net/netfilter/xt_owner.c

@@ -25,6 +25,9 @@ static int owner_check(const struct xt_mtchk_param *par)
 	struct xt_owner_match_info *info = par->matchinfo;
 	struct net *net = par->net;
 
+	if (info->match & ~XT_OWNER_MASK)
+		return -EINVAL;
+
 	/* Only allow the common case where the userns of the writer
 	 * matches the userns of the network namespace.
 	 */