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Gmane
From: Matthew Garrett <matthew.garrett <at> nebula.com>
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot
Newsgroups: gmane.linux.kernel.lsm
Date: Wednesday 13th February 2013 05:39:22 UTC (over 4 years ago)
On Tue, 2013-02-12 at 16:48 -0800, H. Peter Anvin wrote:

> OK... what none of this gets into:
> 
> Why should CAP_RAWIO be allowed on a secure boot system, when there are
> 2^n known ways of compromise a system with CAP_RAWIO?

CAP_SYS_RAWIO seems to have ended up being a catchall of "Maybe someone
who isn't entirely root should be able to do this", and not everything
it covers is equivalent to being able to compromise the running kernel.
I wouldn't argue with the idea that maybe we should just reappraise most
of the current uses of CAP_SYS_RAWIO, but removing capability checks
from places that currently have them seems like an invitation for
userspace breakage.
 
CD: 2ms