Re: [PATCH v4 26/39] x86/shstk: Add user-mode shadow stack support

[Kees Cook]

On Fri, Dec 02, 2022 at 04:35:53PM -0800, Rick Edgecombe wrote:
> From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> 
> Introduce basic shadow stack enabling/disabling/allocation routines.
> A task's shadow stack is allocated from memory with VM_SHADOW_STACK flag
> and has a fixed size of min(RLIMIT_STACK, 4GB).
> 
> Keep the task's shadow stack address and size in thread_struct. This will
> be copied when cloning new threads, but needs to be cleared during exec,
> so add a function to do this.
> 
> Do not support IA32 emulation or x32.
> 
> Tested-by: Pengfei Xu <pengfei.xu@xxxxxxxxx>
> Tested-by: John Allen <john.allen@xxxxxxx>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook