linux-kernel - Re: Trusted kernel patchset for Secure Boot lockdown

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Message-ID: <1394746248.27846.3.camel@x230>
Date:	Thu, 13 Mar 2014 21:30:48 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	"gnomes@...rguk.ukuu.org.uk" <gnomes@...rguk.ukuu.org.uk>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jmorris@...ei.org" <jmorris@...ei.org>,
	"keescook@...omium.org" <keescook@...omium.org>,
	"linux-security-module@...r.kernel.org" 
	<linux-security-module@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"hpa@...or.com" <hpa@...or.com>,
	"jwboyer@...oraproject.org" <jwboyer@...oraproject.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Subject: Re: Trusted kernel patchset for Secure Boot lockdown

On Thu, 2014-03-13 at 21:24 +0000, One Thousand Gnomes wrote:

> If I have CAP_SYS_RAWIO I can make arbitary ring 0 calls from userspace,
> trivially and in a fashion well known and documented.

How?

> You've missed a few others too - mem= (especially with exactmap) for
> example.

/dev/mem access is restricted, so what would this buy you? The potential
to have the kernel hand over a region belonging to hardware in response
to a userspace allocation?

-- 
Matthew Garrett <matthew.garrett@...ula.com>