Re: [PATCH v27 30/31] mm: Update arch_validate_flags() to test vma anonymous

[Yu, Yu-cheng]

On 5/25/2021 4:00 AM, Catalin Marinas wrote:
> On Fri, May 21, 2021 at 03:12:10PM -0700, Yu-cheng Yu wrote:
> > When newer VM flags are being created, such as VM_MTE, it becomes necessary
> > for mmap/mprotect to verify if certain flags are being applied to an
> > anonymous VMA.
> >
> > To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
> > is specified [1], and then using the flag in arch_validate_flags().
> >
> > Another approach is passing the VMA to arch_validate_flags(), and check
> > vma_is_anonymous().
> >
> > To prepare the introduction of PROT_SHADOW_STACK, which creates a shadow
> > stack mapping and can be applied only to an anonymous VMA, update
> > arch_validate_flags() to pass in the VMA.
> >
> > [1] commit 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()"),
> >
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> > Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> > Cc: Will Deacon <will@xxxxxxxxxx>
>
> For arm64:
>
> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Thanks!