From mboxrd@z Thu Jan  1 00:00:00 1970
From: "H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot
Date: Wed, 13 Feb 2013 14:24:04 -0800
Message-ID: <511C1284.6080304@zytor.com>
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To: Paolo Bonzini <pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Matthew Garrett <matthew.garrett-05XSO3Yj/JvQT0dZR+AlfA@public.gmane.org>, Borislav Petkov <bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org>, Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>, Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" <x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, "linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-security-module <linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
List-Id: linux-efi@vger.kernel.org

On 02/13/2013 11:55 AM, Paolo Bonzini wrote:
> Il 13/02/2013 18:22, H. Peter Anvin ha scritto:
>>>
>>> On non-x86 machines CAP_SYS_RAWIO is much less dangerous, especially
>>> when coupled with file DAC.
>
> Discretionary Access Control.
>
>> Either way, I think you are at best deluded and more like you just
>> completely wrong about CAP_SYS_RAWIO being "less dangerous on non-x86
>> machines".  With the possible exception of s390 I suspect it is, in
>> fact, more dangerous.
>
> I may well be wrong, but as a quick data point CAP_SYS_RAWIO has no
> occurrences in arch/ except arch/x86.  Of course a lot of driver
> functionality will be limited to CAP_SYS_RAWIO, but usually this
> requires having a file descriptor for some file.
>

Well, yes, although that could include /dev/mem.

	-hpa


-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.