Commit fdf5af0d authored Dec 02, 2011 by Eric Dumazet Committed by David S. Miller Dec 04, 2011

tcp: drop SYN+FIN messages



Denys Fedoryshchenko reported that SYN+FIN attacks were bringing his
linux machines to their limits.

Dont call conn_request() if the TCP flags includes SYN flag

Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 78a8a36f

net/ipv4/tcp_input.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -5811,6 +5811,8 @@ int tcp_rcv_state_process(struct sock sk, struct sk_buff skb,
	goto discard;		goto discard;

	if (th->syn) {		if (th->syn) {
			if (th->fin)
			goto discard;
	if (icsk->icsk_af_ops->conn_request(sk, skb) < 0)		if (icsk->icsk_af_ops->conn_request(sk, skb) < 0)
	return 1;		return 1;