Re: [PATCH] x86: Lock down MSR writing in secure boot

[H. Peter Anvin]

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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