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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 B21F3C4363D for ; Fri, 2 Oct 2020 13:31:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 847D4206FA for ; Fri, 2 Oct 2020 13:31:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387856AbgJBNba (ORCPT ); Fri, 2 Oct 2020 09:31:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726282AbgJBNba (ORCPT ); Fri, 2 Oct 2020 09:31:30 -0400 Received: from orbyte.nwl.cc (orbyte.nwl.cc [IPv6:2001:41d0:e:133a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5B74C0613D0 for ; Fri, 2 Oct 2020 06:31:29 -0700 (PDT) Received: from n0-1 by orbyte.nwl.cc with local (Exim 4.94) (envelope-from ) id 1kOL9j-0001S0-LE; Fri, 02 Oct 2020 15:31:27 +0200 Date: Fri, 2 Oct 2020 15:31:27 +0200 From: Phil Sutter To: Pablo Neira Ayuso Cc: Arturo Borrero Gonzalez , netfilter-devel@vger.kernel.org Subject: Re: [iptables PATCH] iptables-nft: fix basechain policy configuration Message-ID: <20201002133127.GD29050@orbyte.nwl.cc> Mail-Followup-To: Phil Sutter , Pablo Neira Ayuso , Arturo Borrero Gonzalez , netfilter-devel@vger.kernel.org References: <160163907669.18523.7311010971070291883.stgit@endurance> <20201002120732.GB29050@orbyte.nwl.cc> <20201002121558.GA1367@salvia> <20201002122852.GC29050@orbyte.nwl.cc> <20201002124741.GA2232@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201002124741.GA2232@salvia> Sender: Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Fri, Oct 02, 2020 at 02:47:41PM +0200, Pablo Neira Ayuso wrote: > On Fri, Oct 02, 2020 at 02:28:52PM +0200, Phil Sutter wrote: > > On Fri, Oct 02, 2020 at 02:15:58PM +0200, Pablo Neira Ayuso wrote: > > > On Fri, Oct 02, 2020 at 02:07:32PM +0200, Phil Sutter wrote: > > > > Hi, > > > > > > > > On Fri, Oct 02, 2020 at 01:44:36PM +0200, Arturo Borrero Gonzalez wrote: > > > > > Previous to this patch, the basechain policy could not be properly configured if it wasn't > > > > > explictly set when loading the ruleset, leading to iptables-nft-restore (and ip6tables-nft-restore) > > > > > trying to send an invalid ruleset to the kernel. > > > > > > > > I fear this is not sufficient: iptables-legacy-restore leaves the > > > > previous chain policy in place if '-' is given in dump file. Please try > > > > this snippet from a testcase I wrote: > > > > > > > > $XT_MULTI iptables -P FORWARD DROP > > > > > > > > diff -u -Z <($XT_MULTI iptables-save | grep '^:FORWARD') \ > > > > <(echo ":FORWARD DROP [0:0]") > > > > > > > > $XT_MULTI iptables-restore -c <<< "$TEST_RULESET" > > > > diff -u -Z <($XT_MULTI iptables-save | grep '^:FORWARD') \ > > > > <(echo ":FORWARD DROP [0:0]") > > > > > > Hm, this is how it works in this patch right? > > > > > > I mean, if '-' is given, chain policy attribute in the netlink message > > > is not set, and the kernel sets chain policy to > > > NFT_CHAIN_POLICY_UNSET. > > > > > > Or am I missing anything? > > > > This is *flushing* iptables-restore. We're dropping the chain first and > > then reinstall it. > > OK, so this fix only works with --noflush. > > If --noflush is not specified, then it should be possible to extend > the cache to dump the chains, get the existing policy and use it. nft_cmd_chain_restore() already sets NFT_CL_CHAINS. > There is now a phase to evaluate the cache requirements, so you can > fetch this. Then, from the netlink phase, look up for the existing > policy in the cache and use it. After the cache is fetched, nft_table_flush() runs before nft_chain_restore() does. > > Another quirk is that iptables-legacy-restore ignores the counters if > > policy is '-' even if --counters flag was given. (: > > OK, so this needs two more fixed on top of this one. In Arturo's mail, he doesn't use --noflush. Not sure if this is just his reproducer or if OpenStack doesn't use --noflush, either. If so, your fix won't help with his problem. Arturo, does fixing --noflush suffice for your case? If so, we could delay the "--flush" case "for later". ;) Cheers, Phil