Re: [GIT PULL] Load keys from signed PE binaries

Matthew Garrett
2013-02-25T15:45:54Z

On Mon, Feb 25, 2013 at 03:28:32PM +0100, Florian Weimer wrote:

> But what puzzles me most is why anyone would assume that the UEFI
> application signing process somehow ensures that the embedded
> certificate is non-malicious. We cannot even track it back to the
> submitter because the third-pary market place UEFI authority only
> issues pseudonymous proxy certificates. This utterly useless for any
> purpose whatsoever, with the notable exception of avoding one
> additional step when setting up a dual-boot machine (which will not
> even work reliably until we switch to overwriting the Windows boot
> loader, like in the pre-UEFI days).

If your firmware trusts objects signed by Microsoft, you have to assume
that objects signed by Microsoft are trustworthy. There's no way to
build a security model otherwise. Are Microsoft trustworthy? We don't
know. If you don't trust Microsoft, remove their key from db.

> Seriously, folks, can we go back one step and discuss what problem you
> are trying to solve? Is it about allowing third-party kernel modules
> in an environment which does not allow unsigned ring 0 code execution?

The problem I'm trying to solve is "Don't permit Linux to be used as a
bootloader for backdoored versions of other operating systems". Any
other security benefit is a happy side effect.

--
Matthew Garrett | mjg59@srcf.ucam.org