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 ECF89C433E7 for ; Fri, 9 Oct 2020 08:51:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E11522272 for ; Fri, 9 Oct 2020 08:51:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732898AbgJIIvt (ORCPT ); Fri, 9 Oct 2020 04:51:49 -0400 Received: from correo.us.es ([193.147.175.20]:41308 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732492AbgJIIvt (ORCPT ); Fri, 9 Oct 2020 04:51:49 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 95ACB396275 for ; Fri, 9 Oct 2020 10:51:46 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 872A3DA844 for ; Fri, 9 Oct 2020 10:51:46 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 7C1DDDA7E1; Fri, 9 Oct 2020 10:51:46 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 52883DA730; Fri, 9 Oct 2020 10:51:44 +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, 09 Oct 2020 10:51:44 +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 3025642EF4E0; Fri, 9 Oct 2020 10:51:44 +0200 (CEST) Date: Fri, 9 Oct 2020 10:50:39 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Phil Sutter , Arturo Borrero Gonzalez , netfilter-devel@vger.kernel.org, kadlec@netfilter.org Subject: Re: [iptables PATCH] iptables-nft: fix basechain policy configuration Message-ID: <20201009085039.GB7851@salvia> References: <160163907669.18523.7311010971070291883.stgit@endurance> <20201008173156.GA14654@salvia> <20201009082953.GD13016@orbyte.nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201009082953.GD13016@orbyte.nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Cc'ing Jozsef. On Fri, Oct 09, 2020 at 10:29:53AM +0200, Phil Sutter wrote: > Hi Pablo, > > On Thu, Oct 08, 2020 at 07:31:56PM +0200, Pablo Neira Ayuso wrote: > > On Fri, Oct 02, 2020 at 01:44:36PM +0200, Arturo Borrero Gonzalez wrote: > > > From: Pablo Neira Ayuso > > > > > > 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 have applied this with some amendments to the test file to cover > > the --noflush case. I think this is a real problem there, where you > > can combine to apply incremental updates to the ruleset. > > Yes, at least I can imagine people relying upon this behaviour. > > > For the --flush case, I still have doubts how to use this feature, not > > sure it is worth the effort to actually fix it. > > I even find it unintuitive as it retains state despite flushing. So am I. > But that is a significant divergence between legacy and nft: > > | # iptables -P FORWARD DROP > | # iptables-restore < | *filter > | COMMIT > | EOF > | # iptables-save > > With legacy, the output is: > > | *filter > | :INPUT ACCEPT [0:0] > | :FORWARD DROP [0:0] > | :OUTPUT ACCEPT [0:0] > | COMMIT > > With nft, there's no output at all. What do you think, should we fix > that? If so, which side? Looks like a variant of the same usecase. So if basechains are not specified, then basechains policies are left as is, but ruleset is flushed. Semantics for this are: Flush out _everything_ (existing rules and non-chains) but only leave existing basechain policies in place as is. I wonder if this is intentional or a side effect of the --noflush support. I'm Cc'ing Jozsef, maybe he remembers. Because you're reaching my boundaries on the netfilter history for this one :-) > > We can revisit later, you can rewrite this later Phil. > > Sure, no problem. Thanks.