Re: [GIT PULL] Load keys from signed PE binaries

Florian Weimer
2013-02-28T19:26:32Z

* Chris Friesen:

> On 02/28/2013 01:57 AM, Florian Weimer wrote:
>
>> In any case, there's another reading of the UEFI Secure Boot
>> requirements: you may run any code you wish after calling
>> ExitBootServices(). That could be an unsigned, traditional GRUB. But
>> this will not generally address the issue of dual-booting Windows 8 in
>> such a way that Windows sees that the device has enabled Microsoft
>> Secure Boot.
>
> Would it be possible to have a signed bootloader that allows booting
> Win8 from within the secure environment, or it could exit the secure
> environment and run unsigned grub?

On systems where the firmware supports multiple boot loaders, this
would work.

On systems which support just one boot loader, the next-stage boot
loader could be signed or not, it would not have access to the
privileged Secure Boot environment. The decision to boot the
Secure-Boot-capable operating system would have to be made before
calling ExitBootServices(), otherwise that operating system will not
see Secure Boot support.