From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: Re: [PATCH v3 1/1] iptables: Fix crash on malformed iptables-restore Date: Fri, 19 May 2017 13:36:13 +0200 Message-ID: <20170519113613.GD28091@breakpoint.cc> References: <1495187664-7807-1-git-send-email-ojford@gmail.com> <20170519100410.GB28091@breakpoint.cc> <20170519103825.GC28091@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Florian Westphal , netfilter-devel@vger.kernel.org To: Oliver Ford Return-path: Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:59922 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753950AbdESLg4 (ORCPT ); Fri, 19 May 2017 07:36:56 -0400 Content-Disposition: inline In-Reply-To: Sender: netfilter-devel-owner@vger.kernel.org List-ID: Oliver Ford wrote: > On Fri, May 19, 2017 at 11:38 AM, Florian Westphal wrote: > > Oliver Ford wrote: > >> On Fri, May 19, 2017 at 11:04 AM, Florian Westphal wrote: > >> > Oliver Ford wrote: > >> >> Filter a beginning '--t'. Because the getopt_long function allows abbreviations, > >> >> any parameter beginning with '--t' will be treated as '--table'. > >> > > >> > No, thats not correct: > >> > --t is treated as --table. > >> > --tfoo is an invalid option. > >> > --ttl is ttl. > >> > > >> > So this: > >> > > >> >> + || !strncmp(param_buffer, "--t", 3)) { > >> >> xtables_error(PARAMETER_PROBLEM, > >> >> + "The -t option (seen in line %u) cannot be " > >> >> + "used in ip6tables-restore.\n", line); > >> > > >> > .. rejects rules like > >> > > >> > -A INPUT -m ttl --ttl 32 > >> > >> Would strncmp(param_buffer, "--ta", 4) work? I don't think there are > >> any options that begin with --ta other than --table. > > > > That won't catch '--t'. > > > > It will also add trouble later if any module adds an option like --tap, > > --tail, --target, etc. > > > > Whats wrong with: > > > > if ((param_buffer[0] == '-' && param_buffer[1] != '-' && > > strchr(param_buffer, 't') || > > (!strncmp(param_buffer, "--t", 3) && > > !strncmp(param_buffer, "--table", strlen(param_buffer)))) { > > > > ? > > I've just sent v4 that definitely works now. If you've got > "!strncmp(param_buffer, "--table", strlen(param_buffer))" you don't > also need "!strncmp(param_buffer, "--t", 3)" as --t will get filtered. Its needed, else '--' marker gets detected as 'table', e.g.: -A INPUT -m ttl --ttl 32 -j ACCEPT --