Re: [PATCH v2 0/4] kselftests/arm64: add PAuth tests

[Shuah Khan <skhan@linuxfoundation.org>]

On 8/31/20 5:04 AM, Boyan Karatotev wrote:
> 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 unique for a single thread
> 	* exec() changes all keys to new unique 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 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>
> 
> 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
>      key uniqueness
> 
>   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       |  35 ++
>   tools/testing/selftests/arm64/pauth/helper.c  |  40 ++
>   tools/testing/selftests/arm64/pauth/helper.h  |  29 ++
>   tools/testing/selftests/arm64/pauth/pac.c     | 348 ++++++++++++++++++
>   .../selftests/arm64/pauth/pac_corruptor.S     |  35 ++
>   8 files changed, 529 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
> 
> --
> 2.17.1
> 
> 

Will, Catalin,

Patches look good to me from selftests perspective. My acked by
for these patches to go through arm64.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>

If you would like me to take these through kselftest tree, give
me your Acks. I can queue these up for 5.10-rc1

thanks,
-- Shuah



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