[Bug 1574727] Re: [SRU] Enforce using signed kernels and modules on UEFI

Mathieu Trudel-Lapierre mathieu.tl at gmail.com
Fri May 27 14:07:20 UTC 2016


** Also affects: efibootmgr (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: efibootmgr (Ubuntu)
       Status: New => Fix Released

** Changed in: efibootmgr (Ubuntu Xenial)
       Status: New => Fix Released

** Changed in: efibootmgr (Ubuntu Wily)
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/1574727

Title:
  [SRU] Enforce using signed kernels and modules on UEFI

Status in dkms package in Ubuntu:
  Fix Released
Status in efibootmgr package in Ubuntu:
  Fix Released
Status in efivar package in Ubuntu:
  Fix Released
Status in grub2 package in Ubuntu:
  New
Status in grub2-signed package in Ubuntu:
  New
Status in mokutil package in Ubuntu:
  Fix Released
Status in shim package in Ubuntu:
  New
Status in shim-signed package in Ubuntu:
  Fix Released
Status in dkms source package in Precise:
  New
Status in efibootmgr source package in Precise:
  New
Status in efivar source package in Precise:
  New
Status in grub2 source package in Precise:
  New
Status in grub2-signed source package in Precise:
  New
Status in mokutil source package in Precise:
  New
Status in shim source package in Precise:
  New
Status in shim-signed source package in Precise:
  New
Status in dkms source package in Trusty:
  New
Status in efibootmgr source package in Trusty:
  New
Status in efivar source package in Trusty:
  Fix Committed
Status in grub2 source package in Trusty:
  New
Status in grub2-signed source package in Trusty:
  New
Status in mokutil source package in Trusty:
  Fix Committed
Status in shim source package in Trusty:
  New
Status in shim-signed source package in Trusty:
  New
Status in dkms source package in Wily:
  New
Status in efibootmgr source package in Wily:
  Fix Released
Status in efivar source package in Wily:
  Fix Released
Status in grub2 source package in Wily:
  New
Status in grub2-signed source package in Wily:
  New
Status in mokutil source package in Wily:
  Fix Committed
Status in shim source package in Wily:
  New
Status in shim-signed source package in Wily:
  New
Status in dkms source package in Xenial:
  Fix Released
Status in efibootmgr source package in Xenial:
  Fix Released
Status in efivar source package in Xenial:
  Fix Released
Status in grub2 source package in Xenial:
  New
Status in grub2-signed source package in Xenial:
  New
Status in mokutil source package in Xenial:
  Fix Released
Status in shim source package in Xenial:
  New
Status in shim-signed source package in Xenial:
  New

Bug description:
  [Rationale]
  Secure Boot is good. We want to be able to validate that as much as possible of the boot process happens with signed binaries; from our shim (the part that is loaded by the EFI firmware itself), down to grub2, the kernel, and even loaded modules.

  [Impact]
  All our users booting in UEFI; on all supported releases.

  [Test cases]
  <FIXME: add more test cases>

  Test cases here are separated by the components that need to be
  changed:

  = grub2 =

  Booting signed kernels:
  1) Try to boot a custom kernel
  2) Verify that the kernel will not be loaded by grub (you should see an error message about the signature)

  Prompting on upgrade:
  0) On a system that runs a dkms module (such as r8168-dkms, rtl8812au-dkms, ndiswrapper-dkms, bbswitch-dkms, etc.)
  1) Make sure that validation is enabled and reboot: 'sudo mokutil --enable-validation && sudo reboot'
  2) Upgrade to the new grub2 package (you may need to download the updated package beforehand)
  3) Validate that grub2 prompts you to disable shim validation.

  = dkms =

  Prompting for dkms on install:
  1) Install r8168-dkms
  2) Verify that you're asked to disable shim validation, and walked through the process via debconf prompts.

  Prompting for dkms on upgrade
  0) On a system that runs a dkms module (such as r8168-dkms, rtl8812au-dkms, ndiswrapper-dkms, bbswitch-dkms, etc.)
  1) Make sure that validation is enabled and reboot: 'sudo mokutil --enable-validation && reboot'
  2) Upgrade to the new dkms package (you may need to download the updated package beforehand)
  3) Validate that dkms prompts you to disable shim validation.

  = shim =

  Booting:
  -> Validate that it allows booting grubx64.efi signed with the old key.
  -> Validate that it allows booting grubx64.efi signed with the new key.

  Validation toggle:
  0) Boot the system; verify if /sys/firmware/efi/efivars/MokSBStateRT-* is present;
  If MokSBStateRT is preset:
  1) sudo mokutil --enable-validation && sudo reboot
  2) Validate that Mok asks you if you want to enable validation
  Otherwise:
  1) sudo mokutil --disable-validation && sudo reboot
  2) Validate that Mok asks you if you want to disable validation
  Finally:
  3) Complete the process to toggle validation state, reboot, and verify whether MokSBStateRT is present.
  4) Run mokutil again to toggle validation back to its former state.

  
  [Regression Potential]
  Issues to watch out for:
  - (dkms) not prompting on upgrade of a dkms package/dkms itself if validation is currently enabled (provided debconf does not have dkms/disable_secureboot seen and set to false)
  - (dkms, on new shim) prompting unnecessarily if validation is already disabled
  - (grub) not prompting on upgrade ...
  - (grub) not prompting on upgrade across releases if validation is disabled; without the applied SRU on original release.
  - (grub, on new shim) prompting unecessarily ...
  - (shim) failing to boot on some firmware that doesn't correctly follow specification
  - (shim) failing to load a properly-signed grub
  - (shim) accepting to load a badly-signed grub

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