From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752510AbbBWXv5 (ORCPT <rfc822;w@1wt.eu>);
	Mon, 23 Feb 2015 18:51:57 -0500
Received: from mail-la0-f52.google.com ([209.85.215.52]:44863 "EHLO
	mail-la0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752223AbbBWXvy (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 23 Feb 2015 18:51:54 -0500
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.2.11.1502231040270.21784@gentwo.org>
References: <alpine.DEB.2.11.1502051554500.4876@gentwo.org>
 <alpine.DEB.2.11.1502230856400.21238@gentwo.org> <CALCETrWJCcBBGGp21C4cdtiU79K-P3t+6rFJUWcXcLR1jqrrFQ@mail.gmail.com>
 <alpine.DEB.2.11.1502230950440.21238@gentwo.org> <CALCETrUR7+44ie2fiy0BzC3ktLQ2dcArSL-O3AHnp8kFF92fjg@mail.gmail.com>
 <alpine.DEB.2.11.1502231040270.21784@gentwo.org>
From: Andy Lutomirski <luto@amacapital.net>
Date: Mon, 23 Feb 2015 15:51:33 -0800
Message-ID: <CALCETrXnBvxG7i9A1Q8oS7kr8TG+FuGJMRVBQ_gFsxM6u=qdDA@mail.gmail.com>
Subject: Re: [PATCH] capabilities: Ambient capability set V1
To: Christoph Lameter <cl@linux.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        "Ted Ts'o" <tytso@mit.edu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Andrew G. Morgan" <morgan@kernel.org>,
        Andrew Morton <akpm@linuxfoundation.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Linux API <linux-api@vger.kernel.org>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Austin S Hemmelgarn <ahferroin7@gmail.com>,
        Aaron Jones <aaronmdjones@gmail.com>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        Markku Savela <msa@moth.iki.fi>, Jonathan Corbet <corbet@lwn.net>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Feb 23, 2015 8:41 AM, "Christoph Lameter" <cl@linux.com> wrote:
>
> On Mon, 23 Feb 2015, Andy Lutomirski wrote:
>
> > If you set ambient caps and then run a setuid program (without
> > no_new_privs), then the ambient set *must* be cleared by the kernel
> > because that's what the setuid program expects.  Yes, the whole
>
> Why would a setuid program expect that? I'd say we expect the ambient set
> to remain in effect. What would break if the ambient set would stay
> active?
>

On a total guess: exim, sendmail, sudo, Apache suexec, etc.  Basically
anything that expects setresuid(nonzero values); execve to drop caps.

I haven't checked how many of the examples above actually do this.

--Andy