Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2 1/4] kselftests/arm64: add a basic Pointer Authentication test | From | Amit Kachhap <> | Date | Wed, 16 Sep 2020 17:41:11 +0530 |
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Hi Boyan,
On 8/31/20 4:34 PM, Boyan Karatotev wrote: > PAuth signs and verifies return addresses on the stack. It does so by > inserting a Pointer Authentication code (PAC) into some of the unused top > bits of an address. This is achieved by adding paciasp/autiasp instructions > at the beginning and end of a function. > > This feature is partially backwards compatible with earlier versions of the > ARM architecture. To coerce the compiler into emitting fully backwards > compatible code the main file is compiled to target an earlier ARM version. > This allows the tests to check for the feature and print meaningful error > messages instead of crashing. > > Add a test to verify that corrupting the return address results in a > SIGSEGV on return. > > 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> > --- > tools/testing/selftests/arm64/Makefile | 2 +-
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> + > +/* check that a corrupted PAC results in SIGSEGV */ > +TEST_SIGNAL(corrupt_pac, SIGSEGV) > +{ > + ASSERT_PAUTH_ENABLED(); > + > + pac_corruptor();
With 8.6-Pauth extension merged in arm tree [1]. It makes sense to verify PAC corruption for both SIGSEGV and SIGILL signals.
Code something like below handles both the cases.
----------------------------------------------------------------------------------- int exec_sign_all(struct signatures *signed_vals, size_t val) @@ -187,12 +188,29 @@ int exec_sign_all(struct signatures *signed_vals, size_t val) return 0; }
-/* check that a corrupted PAC results in SIGSEGV */ -TEST_SIGNAL(corrupt_pac, SIGSEGV) +sigjmp_buf jmpbuf; +void pac_signal_handler(int signum, siginfo_t *si, void *uc) { - ASSERT_PAUTH_ENABLED(); + if (signum == SIGSEGV || signum == SIGILL) { + siglongjmp(jmpbuf, 1); + } +} + +/* check that a corrupted PAC results in SIGSEGV or SIGILL */ +TEST(corrupt_pac) +{ + struct sigaction sa;
- pac_corruptor(); + ASSERT_PAUTH_ENABLED(); + if (sigsetjmp(jmpbuf, 1) == 0) { + sa.sa_sigaction = pac_signal_handler; + sa.sa_flags = SA_SIGINFO; + sigemptyset(&sa.sa_mask); + sigaction(SIGSEGV, &sa, NULL); + sigaction(SIGILL, &sa, NULL); + pac_corruptor(); + ASSERT_TRUE(0) TH_LOG("SIGSEGV/SIGILL signal did not occur"); + } }
/* @@ -265,7 +283,7 @@ TEST(single_thread_different_keys)
tmp = n_same_single_set(&signed_vals, nkeys); ---------------------------------------------------------------------------------------
Thanks, Amit Daniel
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/ptrauth
Regards, Amit Daniel > +} > + > +TEST_HARNESS_MAIN
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