Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753433AbdFVRur (ORCPT ); Thu, 22 Jun 2017 13:50:47 -0400 Received: from mail-it0-f52.google.com ([209.85.214.52]:36662 "EHLO mail-it0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbdFVRup (ORCPT ); Thu, 22 Jun 2017 13:50:45 -0400 MIME-Version: 1.0 In-Reply-To: References: <334e6a92-2d41-c9e1-c807-19e493f1af83@kernel.org> From: Kees Cook Date: Thu, 22 Jun 2017 10:50:43 -0700 X-Google-Sender-Auth: zZE_WfTvS0NSmwI4KAIy5aJqrd4 Message-ID: Subject: Re: seccomp ptrace selftest failures with 4.4-stable [Was: Re: LTS testing with latest kselftests - some failures] To: Andy Lutomirski Cc: Shuah Khan , Sumit Semwal , Brian Norris , "Luis R. Rodriguez" , Greg Kroah-Hartman , LKML , "# 3.4.x" , "open list:KERNEL SELFTEST FRAMEWORK" , Shuah Khan Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2211 Lines: 49 On Thu, Jun 22, 2017 at 10:49 AM, Andy Lutomirski wrote: > On Thu, Jun 22, 2017 at 10:09 AM, Shuah Khan wrote: >> On 06/22/2017 10:53 AM, Kees Cook wrote: >>> On Thu, Jun 22, 2017 at 9:18 AM, Sumit Semwal wrote: >>>> Hi Kees, Andy, >>>> >>>> On 15 June 2017 at 23:26, Sumit Semwal wrote: >>>>> 3. 'seccomp ptrace hole closure' patches got added in 4.7 [3] - >>>>> feature and test together. >>>>> - This one also seems like a security hole being closed, and the >>>>> 'feature' could be a candidate for stable backports, but Arnd tried >>>>> that, and it was quite non-trivial. So perhaps we'll need some help >>>>> from the subsystem developers here. >>>> >>>> Could you please help us sort this out? Our goal is to help Greg with >>>> testing stable kernels, and currently the seccomp tests fail due to >>>> missing feature (seccomp ptrace hole closure) getting tested via >>>> latest kselftest. >>>> >>>> If you feel the feature isn't a stable candidate, then could you >>>> please help make the test degrade gracefully in its absence? >>> >>> I don't really want to have that change be a backport -- it's quite >>> invasive across multiple architectures. >>> >>> I would say just add a kernel version check to the test. This is >>> probably not the only selftest that will need such things. :) >> >> Adding release checks to selftests is going to problematic for maintenance. >> Tests should fail gracefully if feature isn't supported in older kernels. >> >> Several tests do that now and please find a way to check for dependencies >> and feature availability and fail the test gracefully. If there is a test >> that can't do that for some reason, we can discuss it, but as a general >> rule, I don't want to see kselftest patches that check release. > > If a future kernel inadvertently loses the new feature and degrades to > the behavior of old kernels, that would be a serious bug and should be > caught. Right. I really think stable kernels should be tested with their own selftests. If some test is needed in a stable kernel it should be backported to that stable kernel. -Kees -- Kees Cook Pixel Security