Pointer Authentication (PAuth) is a security feature introduced in ARMv8.3. It introduces instructions to sign addresses and later check for potential corruption using a second modifier value and one of a set of keys. The signature, in the form of the Pointer Authentication Code (PAC), is stored in some of the top unused bits of the virtual address (e.g. [54: 49] if TBID0 is enabled and TnSZ is set to use a 48 bit VA space). A set of controls are present to enable/disable groups of instructions (which use certain keys) for compatibility with libraries that do not utilize the feature. PAuth is used to verify the integrity of return addresses on the stack with less memory than the stack canary.
This patchset adds kselftests to verify the kernel's configuration of the feature and its runtime behaviour. There are 7 tests which verify that: * an authentication failure leads to a SIGSEGV * the data/instruction instruction groups are enabled * the generic instructions are enabled * all 5 keys are different for a single thread * exec() changes all keys to new different ones * context switching preserves the 4 data/instruction keys * context switching preserves the generic keys
The tests have been verified to work on qemu without a working PAUTH Implementation and on ARM's FVP with a full or partial PAuth implementation.
Changes in v3: * remove double blank lines * Patch 1: "kselftests: add a basic arm64 Pointer Authentication test" * shorten pac_corruptor.S to cut out unnecessary code * add second signal handler to cover ARMv8.6 compatibily * Patch 3: "kselftests/arm64: add PAuth test for whether exec() changes keys" * change name of "exec_unique_keys" to "exec_changed_keys" * change reporting of error to be how many keys were left unchanged * Path 4: "kselftests/arm64: add PAuth tests for single threaded consistency and key uniqueness" * change unique to different * rename "single_thread_unique_keys" to "single_thread_different_keys" * change reporting of error to be how many keys were left unchanged
Changes in v2: * remove extra lines at end of files * Patch 1: "kselftests: add a basic arm64 Pointer Authentication test" * add checks for a compatible compiler in Makefile * Patch 4: "kselftests: add PAuth tests for single threaded consistency and key uniqueness" * rephrase comment for clarity in pac.c
Cc: Shuah Khan shuah@kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Reviewed-by: Vincenzo Frascino Vincenzo.Frascino@arm.com Reviewed-by: Amit Daniel Kachhap amit.kachhap@arm.com Signed-off-by: Boyan Karatotev boyan.karatotev@arm.com Acked-by: Shuah Khan skhan@linuxfoundation.org
Boyan Karatotev (4): kselftests/arm64: add a basic Pointer Authentication test kselftests/arm64: add nop checks for PAuth tests kselftests/arm64: add PAuth test for whether exec() changes keys kselftests/arm64: add PAuth tests for single threaded consistency and differently initialized keys
tools/testing/selftests/arm64/Makefile | 2 +- .../testing/selftests/arm64/pauth/.gitignore | 2 + tools/testing/selftests/arm64/pauth/Makefile | 39 ++ .../selftests/arm64/pauth/exec_target.c | 34 ++ tools/testing/selftests/arm64/pauth/helper.c | 39 ++ tools/testing/selftests/arm64/pauth/helper.h | 28 ++ tools/testing/selftests/arm64/pauth/pac.c | 368 ++++++++++++++++++ .../selftests/arm64/pauth/pac_corruptor.S | 19 + 8 files changed, 530 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/arm64/pauth/.gitignore create mode 100644 tools/testing/selftests/arm64/pauth/Makefile create mode 100644 tools/testing/selftests/arm64/pauth/exec_target.c create mode 100644 tools/testing/selftests/arm64/pauth/helper.c create mode 100644 tools/testing/selftests/arm64/pauth/helper.h create mode 100644 tools/testing/selftests/arm64/pauth/pac.c create mode 100644 tools/testing/selftests/arm64/pauth/pac_corruptor.S
-- 2.28.0