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

[David Lang]

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@xxxxxxxxxxxxxxxxxxx
> <gregkh@xxxxxxxxxxxxxxxxxxx> 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
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