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@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@xxxxxxx>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
Signed-off-by: Boyan Karatotev <boyan.karatotev@xxxxxxx>
---
tools/testing/selftests/arm64/Makefile | 2 +-
[...]
+
+/* 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
[...]
