From mboxrd@z Thu Jan 1 00:00:00 1970 From: gfree.wind@foxmail.com Subject: [PATCH nf-next v2 1/1] netfilter: SYNPROXY: Return NF_STOLEN instead of NF_DROP during handshaking Date: Wed, 12 Apr 2017 10:14:50 +0800 Message-ID: <1491963290-84377-1-git-send-email-gfree.wind@foxmail.com> Cc: Gao Feng To: pablo@netfilter.org, netfilter-devel@vger.kernel.org Return-path: Received: from smtpproxy19.qq.com ([184.105.206.84]:45617 "EHLO smtpproxy19.qq.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751951AbdDLCPF (ORCPT ); Tue, 11 Apr 2017 22:15:05 -0400 Sender: netfilter-devel-owner@vger.kernel.org List-ID: From: Gao Feng Current SYNPROXY codes return NF_DROP during normal TCP handshaking, it is not friendly to caller. Because the nf_hook_slow would treat the NF_DROP as an error, and return -EPERM. As a result, it may cause the top caller think it meets one error. So use NF_STOLEN instead of NF_DROP now because there is no error happened indeed, and free the skb directly. Signed-off-by: Gao Feng --- v2: Add the check for synproxy_recv_client_ack, per Gao Feng, v1: initial version net/ipv4/netfilter/ipt_SYNPROXY.c | 21 ++++++++++++++------- net/ipv6/netfilter/ip6t_SYNPROXY.c | 20 ++++++++++++++------ 2 files changed, 28 insertions(+), 13 deletions(-) diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c index 3240a26..ab0f576 100644 --- a/net/ipv4/netfilter/ipt_SYNPROXY.c +++ b/net/ipv4/netfilter/ipt_SYNPROXY.c @@ -293,12 +293,16 @@ XT_SYNPROXY_OPT_ECN); synproxy_send_client_synack(net, skb, th, &opts); - return NF_DROP; - + consume_skb(skb); + return NF_STOLEN; } else if (th->ack && !(th->fin || th->rst || th->syn)) { /* ACK from client */ - synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq)); - return NF_DROP; + if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) { + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } return XT_CONTINUE; @@ -367,10 +371,13 @@ static unsigned int ipv4_synproxy_hook(void *priv, * number match the one of first SYN. */ if (synproxy_recv_client_ack(net, skb, th, &opts, - ntohl(th->seq) + 1)) + ntohl(th->seq) + 1)) { this_cpu_inc(snet->stats->cookie_retrans); - - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } synproxy->isn = ntohl(th->ack_seq); diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c index 4ef1ddd..6a4f49e 100644 --- a/net/ipv6/netfilter/ip6t_SYNPROXY.c +++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c @@ -307,12 +307,17 @@ XT_SYNPROXY_OPT_ECN); synproxy_send_client_synack(net, skb, th, &opts); - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; } else if (th->ack && !(th->fin || th->rst || th->syn)) { /* ACK from client */ - synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq)); - return NF_DROP; + if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) { + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } return XT_CONTINUE; @@ -388,10 +393,13 @@ static unsigned int ipv6_synproxy_hook(void *priv, * number match the one of first SYN. */ if (synproxy_recv_client_ack(net, skb, th, &opts, - ntohl(th->seq) + 1)) + ntohl(th->seq) + 1)) { this_cpu_inc(snet->stats->cookie_retrans); - - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } synproxy->isn = ntohl(th->ack_seq); -- 1.9.1