netfilter: nfnetlink_queue: do not allow to set unsupported flag bits

Allow setting of only supported flag bits in queue->flags.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter/nfnetlink_queue.h

@@ -95,5 +95,6 @@ enum nfqnl_attr_config {
 /* Flags for NFQA_CFG_FLAGS */
 #define NFQA_CFG_F_FAIL_OPEN			(1 << 0)
 #define NFQA_CFG_F_CONNTRACK			(1 << 1)
+#define NFQA_CFG_F_MAX				(1 << 2)
 
 #endif /* _NFNETLINK_QUEUE_H */

net/netfilter/nfnetlink_queue_core.c

@@ -910,6 +910,11 @@ nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
 		flags = ntohl(nla_get_be32(nfqa[NFQA_CFG_FLAGS]));
 		mask = ntohl(nla_get_be32(nfqa[NFQA_CFG_MASK]));
 
+		if (flags >= NFQA_CFG_F_MAX) {
+			ret = -EOPNOTSUPP;
+			goto err_out_unlock;
+		}
+
 		spin_lock_bh(&queue->lock);
 		queue->flags &= ~mask;
 		queue->flags |= flags & mask;