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, URIBL_BLOCKED,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 95696C433DF for ; Fri, 9 Oct 2020 20:08:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 58BE72053B for ; Fri, 9 Oct 2020 20:08:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391228AbgJIUIo (ORCPT ); Fri, 9 Oct 2020 16:08:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388178AbgJIUF7 (ORCPT ); Fri, 9 Oct 2020 16:05:59 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29AFCC0613D5; Fri, 9 Oct 2020 13:05:59 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1kQyeC-0001He-AQ; Fri, 09 Oct 2020 22:05:48 +0200 Date: Fri, 9 Oct 2020 22:05:48 +0200 From: Florian Westphal To: Jozsef Kadlecsik Cc: Florian Westphal , Francesco Ruggeri , open list , netdev , coreteam@netfilter.org, netfilter-devel@vger.kernel.org, Jakub Kicinski , David Miller , Pablo Neira Ayuso Subject: Re: [PATCH nf v2] netfilter: conntrack: connection timeout after re-register Message-ID: <20201009200548.GG5723@breakpoint.cc> References: <20201007193252.7009D95C169C@us180.sjc.aristanetworks.com> <20201009110323.GC5723@breakpoint.cc> <20201009185552.GF5723@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Jozsef Kadlecsik wrote: > > The "delay unregister" remark was wrt. the "all rules were deleted" > > case, i.e. add a "grace period" rather than acting right away when > > conntrack use count did hit 0. > > Now I understand it, thanks really. The hooks are removed, so conntrack > cannot "see" the packets and the entries become stale. Yes. > What is the rationale behind "remove the conntrack hooks when there are no > rule left referring to conntrack"? Performance optimization? But then the > content of the whole conntrack table could be deleted too... ;-) Yes, this isn't the case at the moment -- only hooks are removed, entries will eventually time out. > > Conntrack entries are not removed, only the base hooks get unregistered. > > This is a problem for tcp window tracking. > > > > When re-register occurs, kernel is supposed to switch the existing > > entries to "loose" mode so window tracking won't flag packets as > > invalid, but apparently this isn't enough to handle keepalive case. > > "loose" (nf_ct_tcp_loose) mode doesn't disable window tracking, it > enables/disables picking up already established connections. > > nf_ct_tcp_be_liberal would disable TCP window checking (but not tracking) > for non RST packets. You are right, mixup on my part. > But both seems to be modified only via the proc entries. Yes, we iterate table on re-register and modify the existing entries.