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 9EA58C47082 for ; Tue, 8 Jun 2021 15:20:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E0476128E for ; Tue, 8 Jun 2021 15:20:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231199AbhFHPWN (ORCPT ); Tue, 8 Jun 2021 11:22:13 -0400 Received: from foss.arm.com ([217.140.110.172]:33356 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230462AbhFHPWM (ORCPT ); Tue, 8 Jun 2021 11:22:12 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 72F346D; Tue, 8 Jun 2021 08:20:19 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 565963F73D; Tue, 8 Jun 2021 08:20:18 -0700 (PDT) Date: Tue, 8 Jun 2021 16:19:18 +0100 From: Dave Martin To: Mark Brown Cc: Catalin Marinas , linux-arch@vger.kernel.org, libc-alpha@sourceware.org, Szabolcs Nagy , Jeremy Linton , Will Deacon , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v1 2/2] arm64: Enable BTI for main executable as well as the interpreter Message-ID: <20210608151914.GJ4187@arm.com> References: <20210521144621.9306-1-broonie@kernel.org> <20210521144621.9306-3-broonie@kernel.org> <20210603154034.GH4187@arm.com> <20210603165134.GF4257@sirena.org.uk> <20210603180429.GI20338@arm.com> <20210607112536.GI4187@arm.com> <20210607181212.GD17957@arm.com> <20210608113318.GA4200@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210608113318.GA4200@sirena.org.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Tue, Jun 08, 2021 at 12:33:18PM +0100, Mark Brown via Libc-alpha wrote: > On Mon, Jun 07, 2021 at 07:12:13PM +0100, Catalin Marinas wrote: > > > I don't think we can document all the filters that can be added on top > > various syscalls, so I'd leave it undocumented (or part of the systemd > > documentation). It was a user space program (systemd) breaking another > > user space program (well, anything with a new enough glibc). The kernel > > ABI was still valid when /sbin/init started ;). > > Indeed. I think from a kernel point of view the main thing is to look > at why userspace feels the need to do things like this and see if > there's anything we can improve or do better with in future APIs, part > of the original discussion here was figuring out that there's not really > any other reasonable options for userspace to implement this check at > the minute. Ack, that would be my policy -- just wanted to make it explicit. It would be good if there were better dialogue between the systemd and kernel folks on this kind of thing. SECCOMP makes it rather easy to (attempt to) paper over kernel/user API design problems, which probably reduces the chance of the API ever being fixed properly, if we're not careful... Cheers ---Dave