From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABB96C742A2 for ; Thu, 11 Jul 2019 22:29:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 79AE220872 for ; Thu, 11 Jul 2019 22:29:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728683AbfGKW3Y (ORCPT ); Thu, 11 Jul 2019 18:29:24 -0400 Received: from Chamillionaire.breakpoint.cc ([193.142.43.52]:38402 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbfGKW3Y (ORCPT ); Thu, 11 Jul 2019 18:29:24 -0400 Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.89) (envelope-from ) id 1hlhZ1-00017V-5F; Fri, 12 Jul 2019 00:29:19 +0200 From: Florian Westphal To: Cc: Florian Westphal , Jakub Jankowski Subject: [PATCH nf] netfilter: conntrack: always store window size un-scaled Date: Fri, 12 Jul 2019 00:29:05 +0200 Message-Id: <20190711222905.22000-1-fw@strlen.de> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Jakub Jankowski reported following oddity: After 3 way handshake completes, timeout of new connection is set to max_retrans (300s) instead of established (5 days). shortened excerpt from pcap provided: 25.070622 IP (flags [DF], proto TCP (6), length 52) 10.8.5.4.1025 > 10.8.1.2.80: Flags [S], seq 11, win 64240, [wscale 8] 26.070462 IP (flags [DF], proto TCP (6), length 48) 10.8.1.2.80 > 10.8.5.4.1025: Flags [S.], seq 82, ack 12, win 65535, [wscale 3] 27.070449 IP (flags [DF], proto TCP (6), length 40) 10.8.5.4.1025 > 10.8.1.2.80: Flags [.], ack 83, win 512, length 0 Turns out the last_win is of u16 type, but we store the scaled value: 512 << 8 (== 0x20000) becomes 0 window. The Fixes tag is not correct, as the bug has existed forever, but without that change all that this causes might cause is to mistake a window update (to-nonzero-from-zero) for a retransmit. Fixes: fbcd253d2448b8 ("netfilter: conntrack: lower timeout to RETRANS seconds if window is 0") Reported-by: Jakub Jankowski Tested-by: Jakub Jankowski Signed-off-by: Florian Westphal --- net/netfilter/nf_conntrack_proto_tcp.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 7ba01d8ee165..9fe1d5e46249 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -475,6 +475,7 @@ static bool tcp_in_window(const struct nf_conn *ct, struct ip_ct_tcp_state *receiver = &state->seen[!dir]; const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple; __u32 seq, ack, sack, end, win, swin; + u16 win_raw; s32 receiver_offset; bool res, in_recv_win; @@ -483,7 +484,8 @@ static bool tcp_in_window(const struct nf_conn *ct, */ seq = ntohl(tcph->seq); ack = sack = ntohl(tcph->ack_seq); - win = ntohs(tcph->window); + win_raw = ntohs(tcph->window); + win = win_raw; end = segment_seq_plus_len(seq, skb->len, dataoff, tcph); if (receiver->flags & IP_CT_TCP_FLAG_SACK_PERM) @@ -658,14 +660,14 @@ static bool tcp_in_window(const struct nf_conn *ct, && state->last_seq == seq && state->last_ack == ack && state->last_end == end - && state->last_win == win) + && state->last_win == win_raw) state->retrans++; else { state->last_dir = dir; state->last_seq = seq; state->last_ack = ack; state->last_end = end; - state->last_win = win; + state->last_win = win_raw; state->retrans = 0; } } -- 2.21.0