Re: Firmware signing -- Re: [PATCH 00/27] security, efi: Add kernel lockdown

[Greg Kroah-Hartman]

On Tue, Nov 14, 2017 at 07:21:38AM -0500, Mimi Zohar wrote:
> On Mon, 2017-11-13 at 14:09 -0800, Linus Torvalds wrote:
> > On Mon, Nov 13, 2017 at 1:44 PM, David Howells <dhowells@xxxxxxxxxx> wrote:
> > >
> > > Whilst that may be true, we either have to check signatures on every bit of
> > > firmware that the appropriate driver doesn't say is meant to be signed or not
> > > bother.
> > 
> > I vote for "not bother".
> > 
> > Seriously, if you have firmware in /lib/firmware, and you don't trust
> > it, what the hell are you doing?
> 
> I might "trust" the files in /lib/firmware, but I also want to make
> sure that they haven't changed.  File signatures provide file
> provenance and integrity guarantees.

Then "verify" them with signatures that you generate yourself.  Like
dm-verify does for the partition that you put the firmware on.

thanks,

greg k-h