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Gmane
From: H. Peter Anvin <hpa <at> zytor.com>
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot
Newsgroups: gmane.linux.kernel.lsm
Date: Wednesday 13th February 2013 06:33:32 UTC (over 4 years ago)
On 02/12/2013 10:27 PM, Matthew Garrett wrote:
> On Tue, 2013-02-12 at 22:12 -0800, H. Peter Anvin wrote:
>
>> Sounds like you are thinking of CAP_SYS_ADMIN, but I don't really see a
>> huge difference between MSRs and I/O control registers... just different
>> address spaces.
>
> Not having CAP_SYS_RAWIO blocks various SCSI commands, for instance.
> These might result in the ability to write individual blocks or destroy
> the device firmware, but do any of them permit modifying the running
> kernel?

That is just batshit crazy.  If you have CAP_SYS_RAWIO you can do iopl() 
which means you can reprogram your northbridge, at which point you most 
definitely *can* modify the running kernel.

And some SCSI driver requires this??!

	-hpa

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

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