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

[Steve Langasek]

The overall plan is that we ARE updating the bootloader, across all
supported Ubuntu releases, to no longer boot unsigned kernels. In
various places the upgrade handling to report problems with unsigned
kernels has landed before the actual change to the bootloader.  This is
correct, we certainly wouldn't want things landing in the opposite order
and render the user's system unbootable!

So the security benefits are coming, but slowly and in a way that
minimizes the impact to the user's system. This specific bug report is
simply about a case where we misreport that the kernel will not be
bootable, and will be fixed in the next upload.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to grub2 in Ubuntu.
https://bugs.launchpad.net/bugs/1788727

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)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1788727/+subscriptions