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=-2.3 required=3.0 tests=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 8B08FCA9EA9 for ; Fri, 18 Oct 2019 14:48:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 644D521D7C for ; Fri, 18 Oct 2019 14:48:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405365AbfJROsJ (ORCPT ); Fri, 18 Oct 2019 10:48:09 -0400 Received: from orbyte.nwl.cc ([151.80.46.58]:44236 "EHLO orbyte.nwl.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729257AbfJROsI (ORCPT ); Fri, 18 Oct 2019 10:48:08 -0400 Received: from n0-1 by orbyte.nwl.cc with local (Exim 4.91) (envelope-from ) id 1iLTXy-0005gq-4c; Fri, 18 Oct 2019 16:48:06 +0200 Date: Fri, 18 Oct 2019 16:48:06 +0200 From: Phil Sutter To: Florian Westphal Cc: Pablo Neira Ayuso , netfilter-devel@vger.kernel.org Subject: Re: [iptables PATCH] xtables-restore: Fix --table parameter check Message-ID: <20191018144806.GG26123@orbyte.nwl.cc> Mail-Followup-To: Phil Sutter , Florian Westphal , Pablo Neira Ayuso , netfilter-devel@vger.kernel.org References: <20190920154920.7927-1-phil@nwl.cc> <20191018140508.GB25052@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191018140508.GB25052@breakpoint.cc> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi Florian, On Fri, Oct 18, 2019 at 04:05:08PM +0200, Florian Westphal wrote: > Phil Sutter wrote: > > Xtables-restore tries to reject rule commands in input which contain a > > --table parameter (since it is adding this itself based on the previous > > table line). Sadly getopt_long's flexibility makes it hard to get this > > check right: Since the last fix, comments starting with a dash and > > containing a 't' character somewhere later were rejected. Simple > > example: > > > > | *filter > > | -A FORWARD -m comment --comment "- allow this one" -j ACCEPT > > | COMMIT > > > > To hopefully sort this once and for all, introduce is_table_param() > > which should cover all possible variants of legal and illegal > > parameters. Also add a test to make sure it does what it is supposed to. > > Thanks for adding a test for this. > How did you generate it? The added code is pure voodoo magic to me, > so I wonder if we can just remove the 'test for -t in iptables-restore > files' code. Sorry, I didn't mean to create such unreadable code. I guess after managing to wrap my head around to understand the old code, the new one seemed much more clear to me. ;) The problem with dropping that check is the potential mess we get when users add '-t' parameter to rules in dumps. While *tables-restore adds '-t' option for the current table itself, arg parsing in at least do_commandeb and do_commandx accepts multiple '-t' options (so the last one wins). Assuming that this checking for '-t' presence is a mess and we should get rid of it, I can imagine two alternatives: 1) Disallow multiple '-t' options. A nice and easy solution, but not backwards compatible. 2) Make *tables-restore add the '-t' option last. This is a bit of a hack and will cause unexpected behaviour for users trying to add '-t' option in dumps. What do you think? Or should I respin after adding a bunch of comments to is_table_param() to make it more clear? Thanks, Phil