From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 11/12] netfilter: SYNPROXY: skip non-tcp packet in {ipv4, ipv6}_synproxy_hook Date: Mon, 9 Oct 2017 18:25:45 +0200 Message-ID: <1507566346-32553-12-git-send-email-pablo@netfilter.org> References: <1507566346-32553-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: Received: from mail.us.es ([193.147.175.20]:57782 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755197AbdJIQ0E (ORCPT ); Mon, 9 Oct 2017 12:26:04 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 95B8AC0B2C for ; Mon, 9 Oct 2017 18:26:03 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 84E50DA399 for ; Mon, 9 Oct 2017 18:26:03 +0200 (CEST) In-Reply-To: <1507566346-32553-1-git-send-email-pablo@netfilter.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Lin Zhang 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 Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_SYNPROXY.c | 3 ++- net/ipv6/netfilter/ip6t_SYNPROXY.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) 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); diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c index a5cd43d75393..437af8c95277 100644 --- a/net/ipv6/netfilter/ip6t_SYNPROXY.c +++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c @@ -353,7 +353,7 @@ static unsigned int ipv6_synproxy_hook(void *priv, nexthdr = ipv6_hdr(skb)->nexthdr; thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off); - if (thoff < 0) + if (thoff < 0 || nexthdr != IPPROTO_TCP) return NF_ACCEPT; th = skb_header_pointer(skb, thoff, sizeof(_th), &_th); -- 2.1.4