From 3c16241c445303a90529565e7437e1f240acfef2 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Tue, 28 Jul 2015 00:53:26 +0200 Subject: [PATCH] netfilter: SYNPROXY: fix sending window update to client Upon receipt of SYNACK from the server, ipt_SYNPROXY first sends back an ACK to finish the server handshake, then calls nf_ct_seqadj_init() to initiate sequence number adjustment of forwarded packets to the client and finally sends a window update to the client to unblock it's TX queue. Since synproxy_send_client_ack() does not set synproxy_send_tcp()'s nfct parameter, no sequence number adjustment happens and the client receives the window update with incorrect sequence number. Depending on client TCP implementation, this leads to a significant delay (until a window probe is being sent). Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_SYNPROXY.c | 3 ++- net/ipv6/netfilter/ip6t_SYNPROXY.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c index fe8cc18..95ea633e 100644 --- a/net/ipv4/netfilter/ipt_SYNPROXY.c +++ b/net/ipv4/netfilter/ipt_SYNPROXY.c @@ -226,7 +226,8 @@ synproxy_send_client_ack(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); + synproxy_send_tcp(skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, + niph, nth, tcp_hdr_size); } static bool diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c index bcebc24..ebbb754 100644 --- a/net/ipv6/netfilter/ip6t_SYNPROXY.c +++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c @@ -243,7 +243,8 @@ synproxy_send_client_ack(const struct synproxy_net *snet, synproxy_build_options(nth, opts); - synproxy_send_tcp(snet, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size); + synproxy_send_tcp(snet, skb, nskb, skb->nfct, IP_CT_ESTABLISHED_REPLY, + niph, nth, tcp_hdr_size); } static bool -- 2.7.4