From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751587AbdF1VVf (ORCPT ); Wed, 28 Jun 2017 17:21:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:60338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751501AbdF1VV3 (ORCPT ); Wed, 28 Jun 2017 17:21:29 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44F0522B60 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org MIME-Version: 1.0 In-Reply-To: References: <20170627151359.GA11756@kroah.com> <20170627151600.GB11756@kroah.com> From: Andy Lutomirski Date: Wed, 28 Jun 2017 14:21:01 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: selftests/capabilities: test FAIL on linux mainline and linux-next and PASS on linux-4.4.70+ To: Kees Cook , "Eric W. Biederman" Cc: Shuah Khan , Andy Lutomirski , Greg KH , Naresh Kamboju , "open list:KERNEL SELFTEST FRAMEWORK" , "linux-kernel@vger.kernel.org" , 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 On Tue, Jun 27, 2017 at 9:35 PM, Kees Cook wrote: > On Tue, Jun 27, 2017 at 4:16 PM, Shuah Khan wrote: >> On 06/27/2017 09:16 AM, Greg KH wrote: >>> On Tue, Jun 27, 2017 at 05:13:59PM +0200, Greg KH wrote: >>>> On Tue, Jun 27, 2017 at 02:10:32PM +0530, Naresh Kamboju wrote: >>>>> selftest capabilities test failed on linux mainline and linux-next and >>>>> PASS on linux-4.4.70+ >>>> >>>> Odd. Any chance you can use 'git bisect' to track down the offending >>>> commit? >>>> >>>> Does this also fail on x86 or any other platform you have available? >>>> Let me go try this on my laptop... >>> >>> Ok, Linus's current tree (4.12.0-rc7+) also fails on this. I'm guessing >>> it's failing, it's hard to understand the output. If only we had TAP >>> output for this test :) >> >> As far as the output, it isn't bad. Not TAP13 will help make it better. >> The problem seems to with the individual messages error/info. messages >> themselves. This test has the quality of a developer unit test and the >> messages could be improved for non-developer use. >> >> I ran the test on 4.11.8-rc1+ and 4.9.35-rc1 see the same failure. >> It would be difficult to bisect this since it spans multiple releases. >> I am hoping Andy can give us some insight. > > I bisected this to: > > commit 380cf5ba6b0a0b307f4afb62b186ca801defb203 > Author: Andy Lutomirski > Date: Thu Jun 23 16:41:05 2016 -0500 > > fs: Treat foreign mounts as nosuid > > I assume the test needs updating, but I bet Andy knows for sure. I can > look into this more closely in the morning. Hi Eric- This is rather odd. The selftest (tools/testing/selftests/capabilities/test_execve), run as root, fails on current kernels. The failure is worked around by this: diff --git a/tools/testing/selftests/capabilities/test_execve.c b/tools/testing/selftests/capabilities/test_execve.c index 10a21a958aaf..6db60889b211 100644 --- a/tools/testing/selftests/capabilities/test_execve.c +++ b/tools/testing/selftests/capabilities/test_execve.c @@ -139,8 +139,8 @@ static void chdir_to_tmpfs(void) if (chdir(cwd) != 0) err(1, "chdir to private tmpfs"); - if (umount2(".", MNT_DETACH) != 0) - err(1, "detach private tmpfs"); +// if (umount2(".", MNT_DETACH) != 0) +// err(1, "detach private tmpfs"); } static void copy_fromat_to(int fromfd, const char *fromname, const char *toname) I think this is due to the line: p->mnt_ns = NULL; in umount_tree(). The test is putting us into a situation in which our cwd has ->mnt_ns = NULL, which is making it act as if it's nosuid. I can imagine this breaking some weird user code (like my test!). Is it a real problem, though?