compare grub efi during build

[Dimitri John Ledkov]

[Impact]

 * When resigning grub in a PPA, one can satisfy the build-depends from the main Ubuntu Archive, without PPA signature ready yet.
 * In such cases, grub2-signed is missbuilt with signature from an old PPA build attached to a newer binary, resulting in validation errors.
 * Add a check to ensure that signed grub & build-depends grub are the same

[Test Case]

 * Copy grub2 from -updates into PPA and await signing
 * Copy grub2-signed from Ubuntu Archive -proposed into PPA
 * Observe that grub2-signed FTBFS, instead of successfully producing uninstallable/unverifiable debs
 * Copy grub2 from -proposed into PPA, and await signing
 * Retry grub2-signed build, which should now succeed

[Regression Potential]

 * Only a build-time quickcheck is added, without any other changes of how signed grub efi images are assembled.

[Other Info]

 * Previously this issue resulted in miss built UC20 grub copies

[Steve Langasek (vorlon)]

Hello Dimitri, or anyone else affected,

Accepted grub2-signed into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/grub2-signed/1.142.6 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Dimitri John Ledkov (xnox)]

I've triggered many successful builds, where grub2 deb & signing artefacts matched, and thus build succeeded.

To produce the race of missmatched grub2 deb & signing artefacts I did the following:

1) edit-acl on a ppa release pocket and self grant admin rights to myself
2) copy .deb from focal-proposed into said ppa
3) whilst signing tarball is still in Accepted queue, use queue tool with '-e' option to filter and reject signing tarball.

This resulted in a PPA that has the latest .deb, but will never have matching signing.

4) copy source-only grub2-signed into said PPA

Expecting a failure to build from source, as the archive that had the candidate deb, did not have matching signing.

make[1]: Entering directory '/<<PKGBUILDDIR>>'
cmp current/grubx64.efi /usr/lib/grub/x86_64-efi/monolithic/grubx64.efi
current/grubx64.efi /usr/lib/grub/x86_64-efi/monolithic/grubx64.efi differ: byte 162, line 2
make[1]: *** [Makefile:27: check] Error 1

And it failed correctly.

Successful builds are visibile in the Ubuntu Archive proposed it self. Thus the build-time check now works correctly.

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub2-signed - 1.142.6

---------------
grub2-signed (1.142.6) focal; urgency=medium

  * Rebuild against grub2 2.04-1ubuntu26.4.
  * Add check to compare that signed grub, matches monolithic builds, to
    avoid signing skew when copying grub2/grub2-signed to PPAs. LP:
    #1894824

 -- Dimitri John Ledkov <email address hidden> Tue, 08 Sep 2020 11:54:34 +0100

[Steve Langasek (vorlon)]

The verification of the Stable Release Update for grub2-signed has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.