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=-5.3 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 52401C4338F for ; Sun, 15 Aug 2021 13:27:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E09260FC3 for ; Sun, 15 Aug 2021 13:27:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238090AbhHON2H (ORCPT ); Sun, 15 Aug 2021 09:28:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232412AbhHON2H (ORCPT ); Sun, 15 Aug 2021 09:28:07 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FA3EC061764 for ; Sun, 15 Aug 2021 06:27:36 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1mFGAn-00006f-KQ; Sun, 15 Aug 2021 15:27:33 +0200 Date: Sun, 15 Aug 2021 15:27:33 +0200 From: Florian Westphal To: Pablo Neira Ayuso Cc: Florian Westphal , Jan Engelhardt , netfilter-devel@vger.kernel.org Subject: Re: [PATCH iptabes-nft] iptables-nft: allow removal of empty builtin chains Message-ID: <20210815132733.GI607@breakpoint.cc> References: <20210814174643.130760-1-fw@strlen.de> <84q02320-o5pp-8q8q-q646-473ssq92n552@vanv.qr> <20210814205314.GF607@breakpoint.cc> <20210815131223.GA30503@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210815131223.GA30503@salvia> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Pablo Neira Ayuso wrote: > On Sat, Aug 14, 2021 at 10:53:14PM +0200, Florian Westphal wrote: > > Indeed. Since this removes the base chain, it implicitly reverts > > a DROP policy too. > > User still has to iptables -F on that given chain before deleting, > right? Yes, -X fails if the chain has rules. > If NLM_F_NONREC is used, the EBUSY is reported when trying to delete > a chain with rules. Yes. > My assumption is that the user will perform: > > iptables-nft -F -t filter > iptables-nft -D -t filter Yes, assuminy you meant -X instead of -D. This behaves just like before, it deletes all rules (-F) and all user-defined chains (-X). > I mean, by when the user has an empty basechain with default policy to > DROP, if they remove the chain, then they are really meaning to remove > the chain and this default policy to DROP. ATM iptables -X $BUILTIN will always fail. In -legecy there is no kernel API to allow for its removal, for -nft there is an extra check that throws an error. > Or am I missing anything else? No, I don't think so. I would prefer if iptables-nft -F -t filter iptables-nft -X -t filter ... would result in an empty "filter" table. I could also add a patch that requests removal of the table as well for the -X case; but unlike base chain the presence of the table alone has no impact on dataplane.