From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH] tcp: md5: fix md5 RST when both sides have listener Date: Wed, 01 Feb 2012 06:09:18 +0100 Message-ID: <1328072958.2617.34.camel@edumazet-laptop> References: <1328053998-2498-1-git-send-email-shawn.lu@ericsson.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: davem@davemloft.net, netdev@vger.kernel.org, xiaoclu@gmail.com To: Shawn Lu Return-path: Received: from mail-wi0-f174.google.com ([209.85.212.174]:61359 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751057Ab2BAFJY (ORCPT ); Wed, 1 Feb 2012 00:09:24 -0500 Received: by wics10 with SMTP id s10so599089wic.19 for ; Tue, 31 Jan 2012 21:09:23 -0800 (PST) In-Reply-To: <1328053998-2498-1-git-send-email-shawn.lu@ericsson.com> Sender: netdev-owner@vger.kernel.org List-ID: Le mardi 31 janvier 2012 =C3=A0 15:53 -0800, Shawn Lu a =C3=A9crit : > TCP RST mechanism is broken in TCP md5(RFC2385). When > connection is gone, md5 key is lost, sending RST > without md5 hash is deem to ignored by peer. This can > be a problem since RST help protocal like bgp to fast > recove from peer crash. >=20 > In most case, users of tcp md5, such as bgp and ldp, > have listeners on both sides. md5 keys for peers are > saved in listening socket. When passive side connection > is gone, we can still get md5 key from listening socket. > When active side of connection is gone, we can try to > find listening socket through source port, and then md5 > key. > we are not loosing sercuriy here: > packet is valified checked with md5 hash. No RST is generated > if md5 hash doesn't match or no md5 key can be found. >=20 > Signed-off-by: Shawn Lu > --- Small notes :=20 1) Always add [PATCH Vx] on your submission if it was a new version of = a previous patch. (V2, V3, V4, ...) If possible, add after the "---" separator an explanation of what changed in your new submission : V3: added some rcu_read_lock()/rcu_read_unlock() sections 2) Also patch title and changelog are a bit confusing. Only the machine receiving the TCP message and answering by RST message needs a listener, in case tcp frame cannot be associated to an existing tcp socket (ESTABLISHED or TIMEWAIT). The other side doesnt need a listener, only a client using TCP MD5 option in its socket. Other than that, your patch seems fine to me. Acked-by: Eric Dumazet Thanks !