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 85081C43457 for ; Wed, 14 Oct 2020 13:02:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE07820848 for ; Wed, 14 Oct 2020 13:02:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731033AbgJNNCC (ORCPT ); Wed, 14 Oct 2020 09:02:02 -0400 Received: from correo.us.es ([193.147.175.20]:35144 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727141AbgJNNCB (ORCPT ); Wed, 14 Oct 2020 09:02:01 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id C3419FC5F0 for ; Wed, 14 Oct 2020 15:01:58 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id B327EDA797 for ; Wed, 14 Oct 2020 15:01:58 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id A7AABDA78E; Wed, 14 Oct 2020 15:01:58 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id AC45ADA791; Wed, 14 Oct 2020 15:01:56 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Wed, 14 Oct 2020 15:01:56 +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 8F9E14301DE0; Wed, 14 Oct 2020 15:01:56 +0200 (CEST) Date: Wed, 14 Oct 2020 15:01:56 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: "Jason A. Donenfeld" Cc: netfilter-devel@vger.kernel.org, Netdev Subject: Re: iptables userspace API broken due to added value in nf_inet_hooks Message-ID: <20201014130156.GB21886@salvia> References: <20201014130115.GA21886@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201014130115.GA21886@salvia> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Oct 14, 2020 at 03:01:15PM +0200, Pablo Neira Ayuso wrote: > On Wed, Oct 14, 2020 at 02:59:47PM +0200, Jason A. Donenfeld wrote: > > Hey Pablo, > > > > In 60a3815da702fd9e4759945f26cce5c47d3967ad, you added another enum > > value to nf_inet_hooks: > > > > --- a/include/uapi/linux/netfilter.h > > +++ b/include/uapi/linux/netfilter.h > > @@ -45,6 +45,7 @@ enum nf_inet_hooks { > > NF_INET_FORWARD, > > NF_INET_LOCAL_OUT, > > NF_INET_POST_ROUTING, > > + NF_INET_INGRESS, > > NF_INET_NUMHOOKS > > }; > > > > That seems fine, but actually it changes the value of > > NF_INET_NUMHOOKS, which is used in struct ipt_getinfo: > > > > /* The argument to IPT_SO_GET_INFO */ > > struct ipt_getinfo { > > /* Which table: caller fills this in. */ > > char name[XT_TABLE_MAXNAMELEN]; > > > > /* Kernel fills these in. */ > > /* Which hook entry points are valid: bitmask */ > > unsigned int valid_hooks; > > > > /* Hook entry points: one per netfilter hook. */ > > unsigned int hook_entry[NF_INET_NUMHOOKS]; > > > > /* Underflow points. */ > > unsigned int underflow[NF_INET_NUMHOOKS]; > > > > /* Number of entries */ > > unsigned int num_entries; > > > > /* Size of entries. */ > > unsigned int size; > > }; > > > > This in turn makes that struct bigger, which means this check in > > net/ipv4/netfilter/ip_tables.c fails: > > > > static int get_info(struct net *net, void __user *user, const int *len) > > { > > char name[XT_TABLE_MAXNAMELEN]; > > struct xt_table *t; > > int ret; > > > > if (*len != sizeof(struct ipt_getinfo)) > > return -EINVAL; > > > > This is affecting my CI, which attempts to use an older iptables with > > net-next and fails with: > > > > iptables v1.8.4 (legacy): can't initialize iptables table `filter': > > Module is wrong version > > Perhaps iptables or your kernel needs to be upgraded. > > > > Is this kind of breakage okay? If there's an exception carved out for > > breaking the iptables API, just let me know, and I'll look into making > > adjustments to work around it in my CI. On the other hand, if this > > breakage was unintentional, now you know. > > Oh right, I'll need a new IPT_INET_NUMHOOKS for this. > > I'll submit a patch, that's for the heads up. s/that's/thanks