Re: shim-signed

[Steve McIntyre <steve@einval.com>]

The Wanderer wrote:
>On 2022-04-26 at 18:05, Paul Wise wrote:
>
>> On Tue, 2022-04-26 at 20:41 +0200, Bastian Blank wrote:
>> 
>>> secure boot signing process at Microsoft is a review-sign process
>> 
>> What kind of review are Microsoft doing of the Debian shim?
>> 
>> Are they reviewing the source and checking for a reproducible build?
>
>I'd be curious to have a more in-depth answer to this, myself.
>
>My understanding has always been that they check to make sure that what
>they're signing is not visibly malicious, and in most cases also that it
>can't chain to load something else (which isn't signed, and might be
>malicious). Since the entire purpose of the shim - at least as I
>understand it - is to chain to load something else, clearly either that
>understanding is not correct, or they're making an exception for the
>case of the shim.

Microsoft themselves *don't* do direct code review of the shim
submissions; they acknowledged some time ago that they didn't have
direct knowledge good enough to make this sensible. Instead, there is
a team of trusted distro maintainers who have stepped up to revies
submissions. See

  * https://github.com/rhboot/shim-review
  * https://github.com/rhboot/shim/wiki

for more information about what we look for. Every single patch that's
applied to a signed shim will be reviewed by the community, and we
also want to see what patches people have aplied to Grub, Linux,
etc. too.

We need a reproducible build for shim so that we can check that the
shipped binary for signing matches what we can rebuild ourselves.

-- 
Steve McIntyre, Cambridge, UK.                                steve@einval.com
"We're the technical experts.  We were hired so that management could
 ignore our recommendations and tell us how to do our jobs."  -- Mike Andrews