linux-kernel - Re: IMA: How to manage user space signing policy with others

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Date:	Thu, 28 Feb 2013 20:49:04 -0500
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Eric Paris <eparis@...isplace.org>
Cc:	Vivek Goyal <vgoyal@...hat.com>,
	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>
Subject: Re: IMA: How to manage user space signing policy with others

On Thu, 2013-02-28 at 17:20 -0500, Eric Paris wrote:
> On Thu, Feb 28, 2013 at 4:35 PM, Vivek Goyal <vgoyal@...hat.com> wrote:
> > On Thu, Feb 28, 2013 at 02:23:39PM -0500, Mimi Zohar wrote:
> 
> I think just a second for both of you to step back and see a slightly
> larger picture/problem might help.
> 
> This is a weird case where Vivek does not trust root to make the
> policy decision.  If the box is configured for secure boot, it needs
> to make these decisions no matter what the admin wants.  This is why
> he talks about trying to merge multiple competing policies.  The
> current IMA policy is controlled by whomever can first write to the
> ima policy file interface.  Vivek does not want an admin to be able to
> overwrite the secureboot policy.  So I get why he thinks changes may
> be needed to support this use case.

Nobody is saying that changes aren't necessary.

> The ima_tcb policy was meant to be larger than needed to determine a
> trusted computing base, but it is clearly not a superset of what he is
> hoping to accomplish.

The 'ima_tcb' policy is for measurement and attestation.  The policy
being discussed here is the 'ima_appraise_tcb' used for enforcing local
file integrity.

> So how do we take a system where the admin/software has some control
> over the integrity policy (as it is today?) and the kernel/system
> itself also has control (as Vivek wants it)?  

> It seems unsolved with what we have today....

Right, and merging policies won't work.  I see where you're going with
this...

thanks!

Mimi

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