Re: [PATCH v4 1/3] efi/libstub: Copy confidential computing secret area

[James Bottomley]

On Wed, 2021-10-20 at 08:39 +0200, Greg KH wrote:
> On Wed, Oct 20, 2021 at 06:14:06AM +0000, Dov Murik wrote:
[...]
> > +	help
> > +	  Copy memory reserved by EFI for Confidential Computing (coco)
> > +	  injected secrets, if EFI exposes such a table entry.
> 
> Why would you want to "copy" secret memory?
> 
> This sounds really odd here, it sounds like you are opening up a
> security hole.  Are you sure this is the correct text that everyone
> on the "COCO" group agrees with?

The way this works is that EFI covers the secret area with a boot time
handoff block, which means it gets destroyed as soon as
ExitBootServices is called as a security measure ... if you do nothing
the secret is shredded.  This means you need to make a copy of it
before that happens if there are secrets that need to live beyond the
EFI boot stub.

James