1 files changed, 385 insertions, 0 deletions
diff --git a/tools/testing/selftests/riscv/cfi/shadowstack.c b/tools/testing/selftests/riscv/cfi/shadowstack.c
new file mode 100644
index 000000000000..f8eed8260a12
--- /dev/null
+++ b/tools/testing/selftests/riscv/cfi/shadowstack.c
@@ -0,0 +1,385 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "../../kselftest.h"
+#include <sys/wait.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <asm-generic/unistd.h>
+#include <sys/mman.h>
+#include "shadowstack.h"
+#include "cfi_rv_test.h"
+
+static struct shadow_stack_tests shstk_tests[] = {
+	{ "shstk fork test\n", shadow_stack_fork_test },
+	{ "map shadow stack syscall\n", shadow_stack_map_test },
+	{ "shadow stack gup tests\n", shadow_stack_gup_tests },
+	{ "shadow stack signal tests\n", shadow_stack_signal_test},
+	{ "memory protections of shadow stack memory\n", shadow_stack_protection_test }
+};
+
+#define RISCV_SHADOW_STACK_TESTS ARRAY_SIZE(shstk_tests)
+
+/* do not optimize shadow stack related test functions */
+#pragma GCC push_options
+#pragma GCC optimize("O0")
+
+void zar(void)
+{
+	unsigned long ssp = 0;
+
+	ssp = csr_read(CSR_SSP);
+	ksft_print_msg("Spewing out shadow stack ptr: %lx\n"
+			"  This is to ensure shadow stack is indeed enabled and working\n",
+			ssp);
+}
+
+void bar(void)
+{
+	zar();
+}
+
+void foo(void)
+{
+	bar();
+}
+
+void zar_child(void)
+{
+	unsigned long ssp = 0;
+
+	ssp = csr_read(CSR_SSP);
+	ksft_print_msg("Spewing out shadow stack ptr: %lx\n"
+			"  This is to ensure shadow stack is indeed enabled and working\n",
+			ssp);
+}
+
+void bar_child(void)
+{
+	zar_child();
+}
+
+void foo_child(void)
+{
+	bar_child();
+}
+
+typedef void (call_func_ptr)(void);
+/*
+ * call couple of functions to test push/pop.
+ */
+int shadow_stack_call_tests(call_func_ptr fn_ptr, bool parent)
+{
+	ksft_print_msg("dummy calls for sspush and sspopchk in context of %s\n",
+		       parent ? "parent" : "child");
+
+	(fn_ptr)();
+
+	return 0;
+}
+
+/* forks a thread, and ensure shadow stacks fork out */
+bool shadow_stack_fork_test(unsigned long test_num, void *ctx)
+{
+	int pid = 0, child_status = 0, parent_pid = 0, ret = 0;
+	unsigned long ss_status = 0;
+
+	ksft_print_msg("Exercising shadow stack fork test\n");
+
+	ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
+	if (ret) {
+		ksft_exit_skip("Shadow stack get status prctl failed with errorcode %d\n", ret);
+		return false;
+	}
+
+	if (!(ss_status & PR_SHADOW_STACK_ENABLE))
+		ksft_exit_skip("Shadow stack is not enabled, should be enabled via glibc\n");
+
+	parent_pid = getpid();
+	pid = fork();
+
+	if (pid) {
+		ksft_print_msg("Parent pid %d and child pid %d\n", parent_pid, pid);
+		shadow_stack_call_tests(&foo, true);
+	} else {
+		shadow_stack_call_tests(&foo_child, false);
+	}
+
+	if (pid) {
+		ksft_print_msg("Waiting on child to finish\n");
+		wait(&child_status);
+	} else {
+		/* exit child gracefully */
+		exit(0);
+	}
+
+	if (pid && WIFSIGNALED(child_status)) {
+		ksft_print_msg("Child faulted, fork test failed\n");
+		return false;
+	}
+
+	return true;
+}
+
+/* exercise 'map_shadow_stack', pivot to it and call some functions to ensure it works */
+#define SHADOW_STACK_ALLOC_SIZE 4096
+bool shadow_stack_map_test(unsigned long test_num, void *ctx)
+{
+	unsigned long shdw_addr;
+	int ret = 0;
+
+	ksft_print_msg("Exercising shadow stack map test\n");
+
+	shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
+
+	if (((long)shdw_addr) <= 0) {
+		ksft_print_msg("map_shadow_stack failed with error code %d\n",
+			       (int)shdw_addr);
+		return false;
+	}
+
+	ret = munmap((void *)shdw_addr, SHADOW_STACK_ALLOC_SIZE);
+
+	if (ret) {
+		ksft_print_msg("munmap failed with error code %d\n", ret);
+		return false;
+	}
+
+	return true;
+}
+
+/*
+ * shadow stack protection tests. map a shadow stack and
+ * validate all memory protections work on it
+ */
+bool shadow_stack_protection_test(unsigned long test_num, void *ctx)
+{
+	unsigned long shdw_addr;
+	unsigned long *write_addr = NULL;
+	int ret = 0, pid = 0, child_status = 0;
+
+	ksft_print_msg("Exercising shadow stack protection test (WPT)\n");
+
+	shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
+
+	if (((long)shdw_addr) <= 0) {
+		ksft_print_msg("map_shadow_stack failed with error code %d\n",
+			       (int)shdw_addr);
+		return false;
+	}
+
+	write_addr = (unsigned long *)shdw_addr;
+	pid = fork();
+
+	/* no child was created, return false */
+	if (pid == -1)
+		return false;
+
+	/*
+	 * try to perform a store from child on shadow stack memory
+	 * it should result in SIGSEGV
+	 */
+	if (!pid) {
+		/* below write must lead to SIGSEGV */
+		*write_addr = 0xdeadbeef;
+	} else {
+		wait(&child_status);
+	}
+
+	/* test fail, if 0xdeadbeef present on shadow stack address */
+	if (*write_addr == 0xdeadbeef) {
+		ksft_print_msg("Shadow stack WPT failed\n");
+		return false;
+	}
+
+	/* if child reached here, then fail */
+	if (!pid) {
+		ksft_print_msg("Shadow stack WPT failed: child reached unreachable state\n");
+		return false;
+	}
+
+	/* if child exited via signal handler but not for write on ss */
+	if (WIFEXITED(child_status) &&
+	    WEXITSTATUS(child_status) != CHILD_EXIT_CODE_SSWRITE) {
+		ksft_print_msg("Shadow stack WPT failed: child wasn't signaled for write\n");
+		return false;
+	}
+
+	ret = munmap(write_addr, SHADOW_STACK_ALLOC_SIZE);
+	if (ret) {
+		ksft_print_msg("Shadow stack WPT failed: munmap failed, error code %d\n",
+			       ret);
+		return false;
+	}
+
+	return true;
+}
+
+#define SS_MAGIC_WRITE_VAL 0xbeefdead
+
+int gup_tests(int mem_fd, unsigned long *shdw_addr)
+{
+	unsigned long val = 0;
+
+	lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
+	if (read(mem_fd, &val, sizeof(val)) < 0) {
+		ksft_print_msg("Reading shadow stack mem via gup failed\n");
+		return 1;
+	}
+
+	val = SS_MAGIC_WRITE_VAL;
+	lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
+	if (write(mem_fd, &val, sizeof(val)) < 0) {
+		ksft_print_msg("Writing shadow stack mem via gup failed\n");
+		return 1;
+	}
+
+	if (*shdw_addr != SS_MAGIC_WRITE_VAL) {
+		ksft_print_msg("GUP write to shadow stack memory failed\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+bool shadow_stack_gup_tests(unsigned long test_num, void *ctx)
+{
+	unsigned long shdw_addr = 0;
+	unsigned long *write_addr = NULL;
+	int fd = 0;
+	bool ret = false;
+
+	ksft_print_msg("Exercising shadow stack gup tests\n");
+	shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
+
+	if (((long)shdw_addr) <= 0) {
+		ksft_print_msg("map_shadow_stack failed with error code %d\n", (int)shdw_addr);
+		return false;
+	}
+
+	write_addr = (unsigned long *)shdw_addr;
+
+	fd = open("/proc/self/mem", O_RDWR);
+	if (fd == -1)
+		return false;
+
+	if (gup_tests(fd, write_addr)) {
+		ksft_print_msg("gup tests failed\n");
+		goto out;
+	}
+
+	ret = true;
+out:
+	if (shdw_addr && munmap(write_addr, SHADOW_STACK_ALLOC_SIZE)) {
+		ksft_print_msg("munmap failed with error code %d\n", ret);
+		ret = false;
+	}
+
+	return ret;
+}
+
+volatile bool break_loop;
+
+void sigusr1_handler(int signo)
+{
+	break_loop = true;
+}
+
+bool sigusr1_signal_test(void)
+{
+	struct sigaction sa = {};
+
+	sa.sa_handler = sigusr1_handler;
+	sa.sa_flags = 0;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(SIGUSR1, &sa, NULL)) {
+		ksft_print_msg("Registering signal handler for SIGUSR1 failed\n");
+		return false;
+	}
+
+	return true;
+}
+
+/*
+ * shadow stack signal test. shadow stack must be enabled.
+ * register a signal, fork another thread which is waiting
+ * on signal. Send a signal from parent to child, verify
+ * that signal was received by child. If not test fails
+ */
+bool shadow_stack_signal_test(unsigned long test_num, void *ctx)
+{
+	int pid = 0, child_status = 0, ret = 0;
+	unsigned long ss_status = 0;
+
+	ksft_print_msg("Exercising shadow stack signal test\n");
+
+	ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
+	if (ret) {
+		ksft_print_msg("Shadow stack get status prctl failed with errorcode %d\n", ret);
+		return false;
+	}
+
+	if (!(ss_status & PR_SHADOW_STACK_ENABLE))
+		ksft_print_msg("Shadow stack is not enabled, should be enabled via glibc\n");
+
+	/* this should be caught by signal handler and do an exit */
+	if (!sigusr1_signal_test()) {
+		ksft_print_msg("Registering sigusr1 handler failed\n");
+		exit(-1);
+	}
+
+	pid = fork();
+
+	if (pid == -1) {
+		ksft_print_msg("Signal test: fork failed\n");
+		goto out;
+	}
+
+	if (pid == 0) {
+		while (!break_loop)
+			sleep(1);
+
+		exit(11);
+		/* child shouldn't go beyond here */
+	}
+
+	/* send SIGUSR1 to child */
+	kill(pid, SIGUSR1);
+	wait(&child_status);
+
+out:
+
+	return (WIFEXITED(child_status) &&
+		WEXITSTATUS(child_status) == 11);
+}
+
+int execute_shadow_stack_tests(void)
+{
+	int ret = 0;
+	unsigned long test_count = 0;
+	unsigned long shstk_status = 0;
+	bool test_pass = false;
+
+	ksft_print_msg("Executing RISC-V shadow stack self tests\n");
+	ksft_set_plan(RISCV_SHADOW_STACK_TESTS);
+
+	ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &shstk_status, 0, 0, 0);
+
+	if (ret != 0)
+		ksft_exit_fail_msg("Get shadow stack status failed with %d\n", ret);
+
+	/*
+	 * If we are here that means get shadow stack status succeeded and
+	 * thus shadow stack support is baked in the kernel.
+	 */
+	while (test_count < RISCV_SHADOW_STACK_TESTS) {
+		test_pass = (*shstk_tests[test_count].t_func)(test_count, NULL);
+		ksft_test_result(test_pass, shstk_tests[test_count].name);
+		test_count++;
+	}
+
+	ksft_finished();
+
+	return 0;
+}
+
+#pragma GCC pop_options