[PATCH v26 4/9] x86/cet/ibt: Update ELF header parsing for Indirect Branch Tracking

Yu-cheng Yu
2021-04-27T20:47:54Z

An ELF file's .note.gnu.property indicates features the file supports.
The property is parsed at loading time and passed to arch_setup_elf_
property(). Update it for Indirect Branch Tracking.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Kees Cook <keescook@chromium.org>
---
v24:
- Update for changes introduced from splitting shadow stack and ibt.

arch/x86/Kconfig | 2 ++
arch/x86/kernel/process_64.c | 8 ++++++++
2 files changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6bb69fba0dad..7436e3a608e8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1970,6 +1970,8 @@ config X86_IBT
def_bool n
depends on X86_SHADOW_STACK
depends on $(cc-option,-fcf-protection)
+ select ARCH_USE_GNU_PROPERTY
+ select ARCH_BINFMT_ELF_STATE
help
Indirect Branch Tracking (IBT) provides protection against
CALL-/JMP-oriented programming attacks. It is active when
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d71045b29475..bf8ef10e5b78 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -864,6 +864,14 @@ int arch_setup_elf_property(struct arch_elf_state *state)
r = shstk_setup();
}

+ if (r < 0)
+ return r;
+
+ if (cpu_feature_enabled(X86_FEATURE_IBT)) {
+ if (state->gnu_property & GNU_PROPERTY_X86_FEATURE_1_IBT)
+ r = ibt_setup();
+ }
+
return r;
}
#endif
--
2.21.0