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 + prompt "Intel Control-flow protection for user-mode" + def_bool n + depends on CPU_SUP_INTEL && X86_64 + depends on AS_WRUSS + select ARCH_USES_HIGH_VMA_FLAGS + select ARCH_HAS_SHADOW_STACK + help + Control-flow protection is a hardware security hardening feature + that detects function-return address or jump target changes by + malicious code. Applications must be enabled to use it, and old + userspace does not get protection "for free". + Support for this feature is present on processors released in + 2020 or later. Enabling this feature increases kernel text size + by 3.7 KB. + See Documentation/x86/intel_cet.rst for more information. + + If unsure, say N. + config EFI bool "EFI runtime service support" depends on ACPI diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler index 26b8c08e2fc4..00c79dd93651 100644 --- a/arch/x86/Kconfig.assembler +++ b/arch/x86/Kconfig.assembler @@ -19,3 +19,8 @@ config AS_TPAUSE def_bool $(as-instr,tpause %ecx) help Supported by binutils >= 2.31.1 and LLVM integrated assembler >= V7 + +config AS_WRUSS + def_bool $(as-instr,wrussq %rax$(comma)(%rbx)) + help + Supported by binutils >= 2.31 and LLVM integrated assembler -- 2.21.0
