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 6C0B4C4707F for ; Thu, 27 May 2021 19:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 507F3613E5 for ; Thu, 27 May 2021 19:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235159AbhE0TcS (ORCPT ); Thu, 27 May 2021 15:32:18 -0400 Received: from mail.netfilter.org ([217.70.188.207]:39382 "EHLO mail.netfilter.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235266AbhE0TcH (ORCPT ); Thu, 27 May 2021 15:32:07 -0400 Received: from netfilter.org (unknown [90.77.255.23]) by mail.netfilter.org (Postfix) with ESMTPSA id 2EE2564504; Thu, 27 May 2021 21:29:31 +0200 (CEST) Date: Thu, 27 May 2021 21:30:30 +0200 From: Pablo Neira Ayuso To: Thomas De Schampheleire Cc: netfilter-devel@vger.kernel.org, thomas.de_schampheleire@nokia.com Subject: Re: [ebtables PATCH 2/2] configure.ac: add option --enable-kernel-64-userland-32 Message-ID: <20210527193030.GA6314@salvia> References: <20210518181730.13436-1-patrickdepinguin@gmail.com> <20210518181730.13436-2-patrickdepinguin@gmail.com> <20210524152621.GA21404@salvia> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Tue, May 25, 2021 at 01:52:27PM +0200, Thomas De Schampheleire wrote: > Hello, > > El lun, 24 may 2021 a las 17:26, Pablo Neira Ayuso > () escribió: > > > > On Tue, May 18, 2021 at 08:17:30PM +0200, Thomas De Schampheleire wrote: > > > From: Thomas De Schampheleire > > > > > > The ebtables build system seems to assume that 'sparc64' is the > > > only case where KERNEL_64_USERSPACE_32 is relevant, but this is not true. > > > This situation can happen on many architectures, especially in embedded > > > systems. For example, an Aarch64 processor with kernel in 64-bit but > > > userland built for 32-bit Arm. Or a 64-bit MIPS Octeon III processor, with > > > userland running in the 'n32' ABI. > > > > > > While it is possible to set CFLAGS in the environment when calling the > > > configure script, the caller would need to know to not only specify > > > KERNEL_64_USERSPACE_32 but also the EBT_MIN_ALIGN value. > > > > > > Instead, add a configure option. All internal details can then be handled by > > > the configure script. > > > > Are you enabling > > > > CONFIG_NETFILTER_XTABLES_COMPAT > > > > in your kernel build? > > > > KERNEL_64_USERSPACE_32 was deprecated long time ago in favour of > > CONFIG_NETFILTER_XTABLES_COMPAT. > > The option you refer to (CONFIG_NETFILTER_XTABLES_COMPAT) was > introduced with commit 47a6959fa331fe892a4fc3b48ca08e92045c6bda > (5.13-rc1). Before that point, it seems CONFIG_COMPAT was the relevant > flag. Sorry, I got confused by this recent commit, it's indeed CONFIG_COMPAT the right toggle in old kernels. > The checks on CONFIG_COMPAT were already introduced with commit > 81e675c227ec60a0bdcbb547dc530ebee23ff931 in 2.6.34.x. > > I have seen this problem on Linux 4.1 and 4.9, on an Aarch64 CPU with > 64-bit kernel and userspace compiled as 32-bit ARM. In both kernels, > CONFIG_COMPAT was set. Hm, then ebtables compat is buggy. > So I am a bit surprised that I bump into this issue after upgrading > ebtables from 2.0.10-4 to 2.0.11 where the padding was removed. > According to your mail and the commits mentioned, it is supposed to > work without ebtables making specific provisions for the 32/64 bit > type difference. > > When I apply the patches I submitted to this list, I get correct > behavior. Without them, the kernel complains and ebtables fails. I understand. If this old userspace infrastructure is restored, then ebtables compat kernel might not ever be fixed.