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

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Message-ID: <1362104227.9158.41.camel@falcor1>
Date:	Thu, 28 Feb 2013 21:17:07 -0500
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org
Subject: Re: IMA: How to manage user space signing policy with others

On Thu, 2013-02-28 at 16:35 -0500, Vivek Goyal wrote:
> On Thu, Feb 28, 2013 at 02:23:39PM -0500, Mimi Zohar wrote:
> 
> [..]
> > I would suggest that the ima_appraise_tcb, which is more restrictive, be
> > permitted to replace the secureboot policy.
> 
> Also ima_appraise_tcb is not necessarily more restrictive. It takes
> appraises only for root user. Files for rest of users are not appraised.

Ok, good point.  

> In general case of "memory locked execution of signed binary" I was
> hoping to give user a flexibility to do appraisal either for root
> or both root and non-root user.
> 
> For the time being I can hardcode things only for root user but the
> moment somebody will extend functionality for non-root user, again
> we will run into the issue that ima_appraise_tcb is not superset so
> we can't allow that.

So we can agree that the 'ima_appraise_tcb' policy is more restrictive
for root owned files.  So as long as the 'ima_appraise_tcb' policy
precedes the secureboot integrity policy, we should be good.

thanks,

Mimi

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