[PATCH v8 01/14] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking

Yu-cheng Yu
2019-08-13T21:03:44Z

The user-mode indirect branch tracking support is done mostly by GCC
to insert ENDBR64/ENDBR32 instructions at branch targets. The kernel
provides CPUID enumeration and feature setup.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/Kconfig | 16 ++++++++++++++++
arch/x86/Makefile | 7 +++++++
2 files changed, 23 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7d13ba326962..666dc66a382e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1940,6 +1940,9 @@ config X86_INTEL_CET
config ARCH_HAS_SHSTK
def_bool n

+config ARCH_HAS_AS_LIMIT
+ def_bool n
+
config X86_INTEL_SHADOW_STACK_USER
prompt "Intel Shadow Stack for user-mode"
def_bool n
@@ -1961,6 +1964,19 @@ config X86_INTEL_SHADOW_STACK_USER

If unsure, say y.

+config X86_INTEL_BRANCH_TRACKING_USER
+ prompt "Intel Indirect Branch Tracking for user-mode"
+ def_bool n
+ depends on CPU_SUP_INTEL && X86_64
+ select X86_INTEL_CET
+ select ARCH_HAS_AS_LIMIT
+ select ARCH_USE_GNU_PROPERTY
+ ---help---
+ Indirect Branch Tracking provides hardware protection against return-/jmp-
+ oriented programming attacks.
+
+ If unsure, say y
+
config EFI
bool "EFI runtime service support"
depends on ACPI
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 0b2e9df48907..25372cc4a303 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -155,6 +155,13 @@ ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER
endif
endif

+# Check compiler ibt support
+ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER
+ ifeq ($(call cc-option-yn, -fcf-protection=branch), n)
+ $(error CONFIG_X86_INTEL_BRANCH_TRACKING_USER not supported by compiler)
+ endif
+endif
+
#
# If the function graph tracer is used with mcount instead of fentry,
# '-maccumulate-outgoing-args' is needed to prevent a GCC bug
--
2.17.1