[Bug 1788727] Re: upgrade crashing due to unsigned kernels

[Steve Langasek]

** Changed in: grub2 (Ubuntu Bionic)
     Assignee: Sarath P Nath (sarathpnath) => (unassigned)

** Changed in: grub2 (Ubuntu Cosmic)
     Assignee: Sarath P Nath (sarathpnath) => (unassigned)

** Changed in: grub2 (Ubuntu Bionic)
       Status: Fix Released => Triaged

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Title:
  upgrade crashing due to unsigned kernels

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2 source package in Bionic:
  Triaged
Status in grub2 source package in Cosmic:
  Fix Released

Bug description:
  [Impact]
  All upgrades on UEFI from xenial to bionic.

  [Test case]
  1) Install Ubuntu 16.04, on an UEFI system with Secure Boot enabled.
  2) Upgrade to 18.04; validate that the upgrade is successful and does not fail due to "unsigned kernels" as an error message / debconf prompt.

  [Regression Potential]
  Things to watch out for are continuing with an upgrade from 16.04 to 18.04 where only unsigned kernels are available, despite the running kernel at upgrade-time being included with a .efi.signed file -- if neither the .efi.signed file is signed nor the vmlinuz for that particular kernel version, the upgrade should fail to avoid letting users upgrade into a non-working system.

  ---

  $ ls /boot/vmlinuz-*
  /boot/vmlinuz-4.4.0-130-generic
  /boot/vmlinuz-4.4.0-130-generic.efi.signed
  /boot/vmlinuz-4.4.0-133-generic
  /boot/vmlinuz-4.4.0-133-generic.efi.signed
  /boot/vmlinuz-4.4.0-134-generic
  /boot/vmlinuz-4.4.0-134-generic.efi.signed
  /boot/vmlinuz-4.4.0-135-generic
  /boot/vmlinuz-4.4.0-135-generic.efi.signed
  $

  On dist-upgrade from xenial to bionic, grub bails with the error:

   │ Cannot upgrade Secure Boot enforcement policy due to unsigned kernels     │
   │                                                                           │
   │ Your system has UEFI Secure Boot enabled in firmware, and the following   │
   │ kernels present on your system are unsigned:                              │
   │                                                                           │
   │  4.4.0-135-generic                                                        │
   │  4.4.0-134-generic                                                        │
   │  4.4.0-133-generic                                                        │
   │                                                                           │
   │                                                                           │
   │ These kernels cannot be verified under Secure Boot.  To ensure your       │
   │ system remains bootable, GRUB will not be upgraded on your disk until     │
   │ these kernels are removed or replaced with signed kernels.                │

  This is a false positive, only the -generic files are unsigned, not
  the .efi.signed ones; and only the .efi.signed ones are referenced in
  the grub.cfg.  So the fact that there are unsigned vmlinuz files in
  the directory alongside the signed ones should not block grub from
  upgrading.

  ---

  ProblemType: Package
  DistroRelease: Ubuntu 18.04
  Package: grub-efi-amd64 2.02-2ubuntu8.3
  Uname: Linux 4.7.0-040700-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.20.9-0ubuntu7.2
  Architecture: amd64
  Date: Thu Aug 23 19:33:07 2018
  ErrorMessage: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 1
  InstallationDate: Installed on 2018-05-30 (85 days ago)
  InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.7.0-040700-generic root=UUID=d9d727a6-5798-4fe1-8ac0-fb79b1d05431 ro quiet splash vt.handoff=7
  Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3ubuntu1
  PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
  RelatedPackageVersions:
   dpkg 1.19.0.5ubuntu2
   apt  1.6.3ubuntu0.1
  SourcePackage: grub2
  Title: package grub-efi-amd64 2.02-2ubuntu8.3 failed to install/upgrade: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 1
  UpgradeStatus: Upgraded to bionic on 2018-08-23 (0 days ago)

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