Re: [PATCH 2/9] x86/cet: Add Kconfig option for user-mode shadow stack

Andy Lutomirski
2018-06-07T15:47:46Z

On Thu, Jun 7, 2018 at 7:40 AM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote:
>
> Introduce Kconfig option X86_INTEL_SHADOW_STACK_USER.
>
> An application has shadow stack protection when all the following are
> true:
>
> (1) The kernel has X86_INTEL_SHADOW_STACK_USER enabled,
> (2) The running processor supports the shadow stack,
> (3) The application is built with shadow stack enabled tools & libs
> and, and at runtime, all dependent shared libs can support shadow
> stack.
>
> If this kernel config option is enabled, but (2) or (3) above is not
> true, the application runs without the shadow stack protection.
> Existing legacy applications will continue to work without the shadow
> stack protection.
>
> The user-mode shadow stack protection is only implemented for the
> 64-bit kernel. Thirty-two bit applications are supported under the
> compatibility mode.
>

The 64-bit only part seems entirely reasonable. So please make the
code 64-bit only :)