diff options
| author | Kristina Martsenko <kristina.martsenko@arm.com> | 2020-03-13 14:35:03 +0530 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-03-18 09:50:21 +0000 |
| commit | 74afda4016a7437e6e425c3370e4b93b47be8ddf (patch) | |
| tree | f3a0e8af80f2e8d500469de8afb34987a7118a1e /arch/arm64/Makefile | |
| parent | c2d920bf1fffc3a61cb77db24464caf39496b32d (diff) | |
arm64: compile the kernel with ptrauth return address signing
Compile all functions with two ptrauth instructions: PACIASP in the
prologue to sign the return address, and AUTIASP in the epilogue to
authenticate the return address (from the stack). If authentication
fails, the return will cause an instruction abort to be taken, followed
by an oops and killing the task.
This should help protect the kernel against attacks using
return-oriented programming. As ptrauth protects the return address, it
can also serve as a replacement for CONFIG_STACKPROTECTOR, although note
that it does not protect other parts of the stack.
The new instructions are in the HINT encoding space, so on a system
without ptrauth they execute as NOPs.
CONFIG_ARM64_PTR_AUTH now not only enables ptrauth for userspace and KVM
guests, but also automatically builds the kernel with ptrauth
instructions if the compiler supports it. If there is no compiler
support, we do not warn that the kernel was built without ptrauth
instructions.
GCC 7 and 8 support the -msign-return-address option, while GCC 9
deprecates that option and replaces it with -mbranch-protection. Support
both options.
Clang uses an external assembler hence this patch makes sure that the
correct parameters (-march=armv8.3-a) are passed down to help it recognize
the ptrauth instructions.
Ftrace function tracer works properly with Ptrauth only when
patchable-function-entry feature is present and is ensured by the
Kconfig dependency.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> # not co-dev parts
Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Cover leaf function, comments, Ftrace Kconfig]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
| -rw-r--r-- | arch/arm64/Makefile | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index dca1a97751ab..f15f92ba53e6 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -65,6 +65,17 @@ stack_protector_prepare: prepare0 include/generated/asm-offsets.h)) endif +ifeq ($(CONFIG_ARM64_PTR_AUTH),y) +branch-prot-flags-$(CONFIG_CC_HAS_SIGN_RETURN_ADDRESS) := -msign-return-address=all +branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf +# -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the +# compiler to generate them and consequently to break the single image contract +# we pass it only to the assembler. This option is utilized only in case of non +# integrated assemblers. +branch-prot-flags-$(CONFIG_AS_HAS_PAC) += -Wa,-march=armv8.3-a +KBUILD_CFLAGS += $(branch-prot-flags-y) +endif + ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) KBUILD_CPPFLAGS += -mbig-endian CHECKFLAGS += -D__AARCH64EB__ |