Re: [PATCH 12/12] Add option to automatically set trusted_kernel when in Secure Boot mode

[Kees Cook]

On Wed, Feb 26, 2014 at 2:48 PM, Matthew Garrett
<matthew.garrett@xxxxxxxxxx> wrote:
> On Wed, 2014-02-26 at 22:41 +0000, One Thousand Gnomes wrote:
>> Another issue that needs addressing is firmware. Quite a few of our
>> request_firmware cases load device firmware which is not signed into DMA
>> capable hardware. Probably also worth checking what the
>> architectural guarantees on bogus microcode updates is. Maybe we need
>> firmware signing for such cases to match the mod signing ?
>
> Vendors keep telling me that they're validating firmware for new
> hardware, and I keep tending not to believe them. Meh. The big problem
> with firmware signatures is that we don't necessarily have the right to
> distribute modified versions of the firmware, so we'd need detached
> signature support. I'm certainly not against this.

I have been working on a patch series for this. It will have LSM hooks
for validating firmware origin (via fd) and contents (via blob),
similar to the changes I made for validating module origins. It just
need to finish testing, and I'll post the series. If you want to check
it out in its current state, it's here:

http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/log/?h=fw-restrict

-Kees

-- 
Kees Cook
Chrome OS Security
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