Re: [PATCH v17 02/26] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection

[Yu, Yu-cheng]

On 1/19/2021 3:06 AM, Borislav Petkov wrote:
> On Tue, Dec 29, 2020 at 01:30:29PM -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_USER 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           | 22 ++++++++++++++++++++++
> >   arch/x86/Kconfig.assembler |  5 +++++
> >   2 files changed, 27 insertions(+)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 7b6dd10b162a..72cff400b9ae 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1950,6 +1950,28 @@ config X86_SGX
> >   
> >   	  If unsure, say N.
> >   
> > +config ARCH_HAS_SHADOW_STACK
> > +	def_bool n
> > +
> > +config X86_CET_USER
>
> That thing needs to be X86_CET. How many times do I need to type this
> before you do it?

Yes, I totally understand that now.  I was still thinking about 
separately enabling user/kernel mode.  Perhaps I should have 
communicated that thought before the change.  Sorry about that.  I will 
update it.

--
Yu-cheng