On 1/19/2021 3:06 AM, Borislav Petkov wrote:

On Tue, Dec 29, 2020 at 01:30:29PM -0800, Yu-cheng Yu wrote:

quoted

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 <redacted>
---
  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