From 49f817d793d1bcc11d721881aac037b996feef5c Mon Sep 17 00:00:00 2001
From: Lin Zhang <xiaolou4617@gmail.com>
Date: Fri, 6 Oct 2017 00:44:03 +0800
Subject: netfilter: SYNPROXY: skip non-tcp packet in {ipv4,
ipv6}_synproxy_hook
In function {ipv4,ipv6}_synproxy_hook we expect a normal tcp packet, but
the real server maybe reply an icmp error packet related to the exist
tcp conntrack, so we will access wrong tcp data.
Fix it by checking for the protocol field and only process tcp traffic.
Signed-off-by: Lin Zhang <xiaolou4617@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/ipv4/netfilter/ipt_SYNPROXY.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
(limited to 'net/ipv4')
diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c
index 811689e523c3..f75fc6b53115 100644
--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
@@ -330,7 +330,8 @@ static unsigned int ipv4_synproxy_hook(void *priv,
if (synproxy == NULL)
return NF_ACCEPT;
- if (nf_is_loopback_packet(skb))
+ if (nf_is_loopback_packet(skb) ||
+ ip_hdr(skb)->protocol != IPPROTO_TCP)
return NF_ACCEPT;
thoff = ip_hdrlen(skb);
--
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