Re: [PATCH v4 15/39] mm: Introduce VM_SHADOW_STACK for shadow stack memory

[Kees Cook]

On Fri, Dec 02, 2022 at 04:35:42PM -0800, Rick Edgecombe wrote:
> From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> 
> The x86 Control-flow Enforcement Technology (CET) feature includes a new
> type of memory called shadow stack. This shadow stack memory has some
> unusual properties, which requires some core mm changes to function
> properly.
> 
> A shadow stack PTE must be read-only and have _PAGE_DIRTY set. However,
> read-only and Dirty PTEs also exist for copy-on-write (COW) pages. These
> two cases are handled differently for page faults. Introduce
> VM_SHADOW_STACK to track shadow stack VMAs.
> 
> 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