From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v2 1/2] tcp: setup timestamp offset when write_seq already set Date: Wed, 22 Feb 2017 16:33:37 -0500 (EST) Message-ID: <20170222.163337.1789197655018339564.davem@davemloft.net> References: <1487759036-2800-1-git-send-email-alexey.kodanev@oracle.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, fw@strlen.de, edumazet@google.com To: alexey.kodanev@oracle.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:43806 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932293AbdBVVdj (ORCPT ); Wed, 22 Feb 2017 16:33:39 -0500 In-Reply-To: <1487759036-2800-1-git-send-email-alexey.kodanev@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Alexey Kodanev Date: Wed, 22 Feb 2017 13:23:55 +0300 > Found that when randomized tcp offsets are enabled (by default) > TCP client can still start new connections without them. Later, > if server does active close and re-uses sockets in TIME-WAIT > state, new SYN from client can be rejected on PAWS check inside > tcp_timewait_state_process(), because either tw_ts_recent or > rcv_tsval doesn't really have an offset set. > > Here is how to reproduce it with LTP netstress tool: > netstress -R 1 & > netstress -H 127.0.0.1 -lr 1000000 -a1 > > [...] > < S seq 1956977072 win 43690 TS val 295618 ecr 459956970 > > . ack 1956911535 win 342 TS val 459967184 ecr 1547117608 > < R seq 1956911535 win 0 length 0 > +1. < S seq 1956977072 win 43690 TS val 296640 ecr 459956970 > > S. seq 657450664 ack 1956977073 win 43690 TS val 459968205 ecr 296640 > > Fixes: 95a22caee396 ("tcp: randomize tcp timestamp offsets for each connection") > Signed-off-by: Alexey Kodanev Applied.