[RFC PATCH 5/5] selftest/x86: Add CET quick test

Yu-cheng Yu
2020-05-21T21:17:51Z

Introduce a quick test to verify shadow stack and IBT are working.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/cet_quick_test.c | 128 +++++++++++++++++++
2 files changed, 129 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/cet_quick_test.c

diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index f1bf5ab87160..26e68272117a 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -14,7 +14,7 @@ CAN_BUILD_CET := $(shell ./check_cc.sh $(CC) trivial_program.c -fcf-protection)
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \
check_initial_reg_state sigreturn iopl ioperm \
protection_keys test_vdso test_vsyscall mov_ss_trap \
- syscall_arg_fault
+ syscall_arg_fault cet_quick_test
TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
diff --git a/tools/testing/selftests/x86/cet_quick_test.c b/tools/testing/selftests/x86/cet_quick_test.c
new file mode 100644
index 000000000000..e84bbbcfd26f
--- /dev/null
+++ b/tools/testing/selftests/x86/cet_quick_test.c
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Quick tests to verify Shadow Stack and IBT are working */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <string.h>
+#include <ucontext.h>
+
+ucontext_t ucp;
+int result[4] = {-1, -1, -1, -1};
+int test_id;
+
+void stack_hacked(unsigned long x)
+{
+ result[test_id] = -1;
+ test_id++;
+ setcontext(&ucp);
+}
+
+#pragma GCC push_options
+#pragma GCC optimize ("O0")
+void ibt_violation(void)
+{
+#ifdef __i386__
+ asm volatile("lea 1f, %eax");
+ asm volatile("jmp *%eax");
+#else
+ asm volatile("lea 1f, %rax");
+ asm volatile("jmp *%rax");
+#endif
+ asm volatile("1:");
+ result[test_id] = -1;
+ test_id++;
+ setcontext(&ucp);
+}
+
+void shstk_violation(void)
+{
+#ifdef __i386__
+ unsigned long x = 0;
+
+ ((unsigned long *)&x)[2] = (unsigned long)stack_hacked;
+#else
+ unsigned long long x = 0;
+
+ ((unsigned long long *)&x)[2] = (unsigned long)stack_hacked;
+#endif
+}
+#pragma GCC pop_options
+
+void segv_handler(int signum, siginfo_t *si, void *uc)
+{
+ result[test_id] = 0;
+ test_id++;
+ setcontext(&ucp);
+}
+
+void user1_handler(int signum, siginfo_t *si, void *uc)
+{
+ shstk_violation();
+}
+
+void user2_handler(int signum, siginfo_t *si, void *uc)
+{
+ ibt_violation();
+}
+
+int main(int argc, char *argv[])
+{
+ struct sigaction sa;
+ int r;
+
+ r = sigemptyset(&sa.sa_mask);
+ if (r)
+ return -1;
+
+ sa.sa_flags = SA_SIGINFO;
+
+ /*
+ * Control protection fault handler
+ */
+ sa.sa_sigaction = segv_handler;
+ r = sigaction(SIGSEGV, &sa, NULL);
+ if (r)
+ return -1;
+
+ /*
+ * Handler to test Shadow stack
+ */
+ sa.sa_sigaction = user1_handler;
+ r = sigaction(SIGUSR1, &sa, NULL);
+ if (r)
+ return -1;
+
+ /*
+ * Handler to test IBT
+ */
+ sa.sa_sigaction = user2_handler;
+ r = sigaction(SIGUSR2, &sa, NULL);
+ if (r)
+ return -1;
+
+ test_id = 0;
+ r = getcontext(&ucp);
+ if (r)
+ return -1;
+
+ if (test_id == 0)
+ shstk_violation();
+ else if (test_id == 1)
+ ibt_violation();
+ else if (test_id == 2)
+ raise(SIGUSR1);
+ else if (test_id == 3)
+ raise(SIGUSR2);
+
+ r = 0;
+ printf("[%s]\tShadow stack\n", result[0] ? "FAIL":"OK");
+ r += result[0];
+ printf("[%s]\tIBT\n", result[1] ? "FAIL":"OK");
+ r += result[1];
+ printf("[%s]\tShadow stack in signal\n", result[2] ? "FAIL":"OK");
+ r += result[2];
+ printf("[%s]\tIBT in signal\n", result[3] ? "FAIL":"OK");
+ r += result[3];
+ return r;
+}
--
2.21.0