Re: [PATCH 00/12] One more attempt at useful kernel lockdown

David Lang
2013-09-10T19:18:32Z

On Tue, 10 Sep 2013, Kees Cook wrote:

> Subject: Re: [PATCH 00/12] One more attempt at useful kernel lockdown
>
> On Tue, Sep 10, 2013 at 11:51 AM, gregkh@linuxfoundation.org
> <gregkh@linuxfoundation.org> wrote:
>> On Tue, Sep 10, 2013 at 11:29:45AM -0700, H. Peter Anvin wrote:
>>> On 09/10/2013 11:26 AM, Matthew Garrett wrote:
>>>> On Tue, 2013-09-10 at 14:23 -0300, Henrique de Moraes Holschuh wrote:
>>>>> On Tue, 10 Sep 2013, Matthew Garrett wrote:
>>>>>> That's why modern systems require signed firmware updates.
>>>>>
>>>>> Linux doesn't. Is someone working on adding signature support to the
>>>>> runtime firmware loader?
>>>>
>>>> It'd be simple to do so, but so far the model appears to be that devices
>>>> that expect signed firmware enforce that themselves.
>>>>
>>>
>>> Most devices do absolutely no verification on the firmware, and simply
>>> trust the driver.
>>>
>>> So signing firmware is probably critical.
>>
>> How are you going to "validate" that the firmware is correct, given
>> that it's just a "blob" living in the linux-firmware tree. If you sign
>> it, what is that saying?
>
> In theory these blobs are traceable to a manufacturer. It's not really
> an indication that it's "safe" more than it's an indication that it
> hasn't been changed. But I haven't chased this very hard yet because
> of below...

well, not if you are trying to defend against root breaking in to the machine.

David Lang