[PATCH 5/7] efi: Get the secure boot status [ver #3]

[James Bottomley]

On Wed, 2016-11-23 at 12:54 +0000, David Howells wrote:
> Get the firmware's secure-boot status in the kernel boot wrapper and 
> stash it somewhere that the main kernel image can find.
> 
> The efi_get_secureboot() function is extracted from the arm stub and 
> (a) generalised so that it can be called from x86 and (b) made to use
> efi_call_runtime() so that it can be run in mixed-mode.
> 
> Suggested-by: Lukas Wunner <lukas at wunner.de>
> Signed-off-by: David Howells <dhowells at redhat.com>

Since you seem to be using this to mean "is the platform locked down?",
this looks to be no longer complete in the UEFI 2.6 world.  If
DeployedMode == 0, even if SecureBoot == 1 and SetupMode == 0, you can
remove the platform key by writing 1 to AuditMode and gain control of
the secure variables.  The lock down state becomes DeployedMode == 1,
SecureBoot == 1 and SetupMode == 0

See the diagram on page 1817

http://www.uefi.org/sites/default/files/resources/UEFI%20Spec%202_6.pdf

James