From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753065AbcGYQ56 (ORCPT ); Mon, 25 Jul 2016 12:57:58 -0400 Received: from mail-vk0-f47.google.com ([209.85.213.47]:34585 "EHLO mail-vk0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752163AbcGYQ54 (ORCPT ); Mon, 25 Jul 2016 12:57:56 -0400 MIME-Version: 1.0 In-Reply-To: <20160725063825.GB12474@gmail.com> References: <8bacd629dcdbb97ee0626912c27a4a09f991b5dd.1466464928.git.luto@kernel.org> <20160725063825.GB12474@gmail.com> From: Andy Lutomirski Date: Mon, 25 Jul 2016 09:57:36 -0700 Message-ID: Subject: Re: [PATCH v3 1/3] x86/ptrace: Stop setting TS_COMPAT in ptrace code To: Ingo Molnar Cc: Pedro Alves , Oleg Nesterov , Kees Cook , Borislav Petkov , "linux-kernel@vger.kernel.org" , X86 ML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Jul 24, 2016 11:38 PM, "Ingo Molnar" wrote: > > > * Andy Lutomirski wrote: > > > On Mon, Jun 20, 2016 at 4:39 PM, Andy Lutomirski wrote: > > > Setting TS_COMPAT in ptrace is wrong: if we happen to do it during > > > syscall entry, then we'll confuse seccomp and audit. (The former > > > isn't a security problem: seccomp is currently entirely insecure if a > > > malicious ptracer is attached.) As a minimal fix, this patch adds a > > > new flag TS_I386_REGS_POKED that handles the ptrace special case. > > > > Hi Ingo- > > > > Could you apply this one patch for 4.8? While I don't think it's a > > significant security issue in 4.7 or earlier, leaving it unfixed in > > 4.8 will introduce a potentially unpleasant interaction with some > > seccomp changes that are queued up in the > > security tree for 4.8. > > > > It will have a trivially-resolvable conflict with -mm. > > > > The rest of the series this is in can wait. > > I don't mind the rest of the series either - could you please repost it (with the > review feedback addressed)? I'm nervous about it for a couple reasons involving the fact that it's user visible. 1. It doesn't make gdb work right in all the cases that gdb currently gets wrong. I haven't had time to think about whether there's a minimal tweak that would fix this. 2. It might have annoying interactions with seccomp whitelists. I don't know that for sure, but I still don't love it. Patch 1 is only user-visible in the case where the current behavior is clearly wrong, so I'd personally be more comfortable applying just patch 1 for 4.8. --Andy