linux-kernel - Re: [PATCH] capabilities: Ambient capability set V1

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Message-ID: <CALCETrXnBvxG7i9A1Q8oS7kr8TG+FuGJMRVBQ_gFsxM6u=qdDA@mail.gmail.com>
Date:	Mon, 23 Feb 2015 15:51:33 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	"Ted Ts'o" <tytso@....edu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Andrew G. Morgan" <morgan@...nel.org>,
	Andrew Morton <akpm@...uxfoundation.org>,
	LSM List <linux-security-module@...r.kernel.org>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Austin S Hemmelgarn <ahferroin7@...il.com>,
	Aaron Jones <aaronmdjones@...il.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Markku Savela <msa@...h.iki.fi>,
	Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH] capabilities: Ambient capability set V1

On Feb 23, 2015 8:41 AM, "Christoph Lameter" <cl@...ux.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
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