Re: [PATCH v20 02/25] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection

[Yu, Yu-cheng]

On 2/10/2021 11:33 AM, Kees Cook wrote:
> On Wed, Feb 10, 2021 at 09:56:40AM -0800, Yu-cheng Yu wrote:
> > Shadow Stack provides protection against function return address
> > corruption.  It is active when the processor supports it, the kernel has
> > CONFIG_X86_CET enabled, and the application is built for the feature.
> > This is only implemented for the 64-bit kernel.  When it is enabled, legacy
> > non-Shadow Stack applications continue to work, but without protection.
> >
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> > ---
> >   arch/x86/Kconfig           | 23 +++++++++++++++++++++++
> >   arch/x86/Kconfig.assembler |  5 +++++
> >   2 files changed, 28 insertions(+)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 21f851179ff0..1138b5fa9b4f 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -28,6 +28,7 @@ config X86_64
> >   	select ARCH_HAS_GIGANTIC_PAGE
> >   	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
> >   	select ARCH_USE_CMPXCHG_LOCKREF
> > +	select ARCH_HAS_SHADOW_STACK
> >   	select HAVE_ARCH_SOFT_DIRTY
> >   	select MODULES_USE_ELF_RELA
> >   	select NEED_DMA_MAP_STATE
> > @@ -1951,6 +1952,28 @@ config X86_SGX
> >   
> >   	  If unsure, say N.
> >   
> > +config ARCH_HAS_SHADOW_STACK
> > +	def_bool n
> > +
> > +config X86_CET
> > +	prompt "Intel Control-flow protection for user-mode"
> > +	def_bool n
> > +	depends on X86_64
>
> This depends isn't needed any more. With that fixed:

Yes, that's right.  I will remove it.

> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

Thanks!

--
Yu-cheng