[PATCH v21 02/26] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection
From: Yu-cheng Yu <hidden>
Date: 2021-02-17 22:31:36
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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 <redacted> Reviewed-by: Kees Cook <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 21f851179ff0..c80cead80a49 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 +1952,27 @@ 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 AS_WRUSS + depends on ARCH_HAS_SHADOW_STACK + select ARCH_USES_HIGH_VMA_FLAGS + help + Control-flow protection is a set of hardware features which place + additional restrictions on indirect branches. These help + mitigate ROP attacks. Applications must be enabled to use it, + and old userspace does not get protection "for free". + Support for this feature is present on Tiger Lake family of + 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