Re: [PATCH v3 3/9] efi/libstub: Remove .note.gnu.property

[Kees Cook]

On Wed, Jun 24, 2020 at 05:31:06PM +0200, Ard Biesheuvel wrote:
> On Wed, 24 Jun 2020 at 17:21, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> >
> > On Wed, Jun 24, 2020 at 12:46:32PM +0200, Ard Biesheuvel wrote:
> > > I'm not sure if there is a point to having PAC and/or BTI in the EFI
> > > stub, given that it runs under the control of the firmware, with its
> > > memory mappings and PAC configuration etc.
> >
> > Is BTI being ignored when the firmware runs?
> 
> Given that it requires the 'guarded' attribute to be set in the page
> tables, and the fact that the UEFI spec does not require it for
> executables that it invokes, nor describes any means of annotating
> such executables as having been built with BTI annotations, I think we
> can safely assume that the EFI stub will execute with BTI disabled in
> the foreseeable future.

yaaaaaay. *sigh* How long until EFI catches up?

That said, BTI shouldn't _hurt_, right? If EFI ever decides to enable
it, we'll be ready?

-- 
Kees Cook