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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 7649BC433E6 for ; Fri, 28 Aug 2020 16:30:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4FB7520872 for ; Fri, 28 Aug 2020 16:30:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726524AbgH1QaV (ORCPT ); Fri, 28 Aug 2020 12:30:21 -0400 Received: from correo.us.es ([193.147.175.20]:44374 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726033AbgH1QaU (ORCPT ); Fri, 28 Aug 2020 12:30:20 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 4811FDA702 for ; Fri, 28 Aug 2020 18:30:19 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 38D90DA730 for ; Fri, 28 Aug 2020 18:30:19 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 2E82FDA72F; Fri, 28 Aug 2020 18:30:19 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 1DC24DA704; Fri, 28 Aug 2020 18:30:17 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Fri, 28 Aug 2020 18:30:17 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id 005EA42EF4E0; Fri, 28 Aug 2020 18:30:16 +0200 (CEST) Date: Fri, 28 Aug 2020 18:30:16 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Florian Westphal Cc: netfilter-devel@vger.kernel.org Subject: Re: [PATCH nf] netfilter: conntrack: do not auto-delete clash entries on reply Message-ID: <20200828163016.GA16743@salvia> References: <20200825220718.12866-1-fw@strlen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200825220718.12866-1-fw@strlen.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Wed, Aug 26, 2020 at 12:07:18AM +0200, Florian Westphal wrote: > Its possible that we have more than one packet with the same ct tuple > simultaneously, e.g. when an application emits n packets on same UDP > socket from multiple threads. > > NAT rules might be applied to those packets. With the right set of rules, > n packets will be mapped to m destinations, where at least two packets end > up with the same destination. > > When this happens, the existing clash resolution may merge the skb that > is processed after the first has been received with the identical tuple > already in hash table. > > However, its possible that this identical tuple is a NAT_CLASH tuple. > In that case the second skb will be sent, but no reply can be received > since the reply that is processed first removes the NAT_CLASH tuple. > > Do not auto-delete, this gives a 1 second window for replies to be passed > back to originator. > > Packets that are coming later (udp stream case) will not be affected: > they match the original ct entry, not a NAT_CLASH one. > > Also prevent NAT_CLASH entries from getting offloaded. Applied, thanks.