Re: [OPTIONAL/RFC v2 37/39] x86/cet: Add PTRACE interface for CET

From: Mike Rapoport
Date: Tue Oct 04 2022 - 04:45:16 EST

On Mon, Oct 03, 2022 at 04:59:43PM -0700, Kees Cook wrote:
> On Thu, Sep 29, 2022 at 03:29:34PM -0700, Rick Edgecombe wrote:
> > From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> >
> > Some applications (like GDB and CRIU) would like to tweak CET state via
> Eee. Does GDB really need this? Can we make this whole thing
> CONFIG-depend on CRIU?

GDB, at least its Intel fork uses this. I don't see how they can jump
between frames without an ability to modify shadow stack contents.

Last I looked they used NT_X86_CET to update SSP and ptrace(POKEDATA) to
write to the shadow stack.

> --
> Kees Cook

Sincerely yours,