From: Florian Westphal Date: Sun, 19 Nov 2017 20:27:28 +0000 (+0100) Subject: netfilter: conntrack: lower timeout to RETRANS seconds if window is 0 X-Git-Tag: v4.15-rc4~13^2~24^2~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fbcd253d2448b8f168241e38f629a36c4c8c1e94;p=thirdparty%2Fkernel%2Flinux.git netfilter: conntrack: lower timeout to RETRANS seconds if window is 0 When zero window is announced we can get into a situation where connection stays around forever: 1. One side announces zero window. 2. Other side closes. In this case, no FIN is sent (stuck in send queue). Unless other side opens the window up again conntrack stays in ESTABLISHED state for a very long time. Lets alleviate this by lowering the timeout to RETRANS (5 minutes), the other end should be sending zero window probes to keep the connection established as long as a socket still exists. Cc: Jozsef Kadlecsik Signed-off-by: Florian Westphal Acked-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index b12fc07111d08..37ef35b861f24 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -1039,6 +1039,9 @@ static int tcp_packet(struct nf_conn *ct, IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) timeout = timeouts[TCP_CONNTRACK_UNACK]; + else if (ct->proto.tcp.last_win == 0 && + timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) + timeout = timeouts[TCP_CONNTRACK_RETRANS]; else timeout = timeouts[new_state]; spin_unlock_bh(&ct->lock);