tools/testing/selftests/rseq/syscall_errors_test.c

// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2024 Michael Jeanson <mjeanson@efficios.com>

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include <assert.h>
#include <stdint.h>
#include <syscall.h>
#include <string.h>
#include <unistd.h>

#include "rseq.h"

static int sys_rseq(void *rseq_abi, uint32_t rseq_len,
		    int flags, uint32_t sig)
{
	return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
}

/*
 * Check the value of errno on some expected failures of the rseq syscall.
 */

int main(void)
{
	struct rseq_abi *global_rseq = rseq_get_abi();
	int ret;
	int errno_copy;

	if (!rseq_available()) {
		fprintf(stderr, "rseq syscall unavailable");
		goto error;
	}

	/* The current thread is NOT registered. */

	/* EINVAL */
	errno = 0;
	ret = sys_rseq(global_rseq, 32, -1, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Registration with invalid flag fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EINVAL)
		goto error;

	errno = 0;
	ret = sys_rseq((char *) global_rseq + 1, 32, 0, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Registration with unaligned rseq_abi fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EINVAL)
		goto error;

	errno = 0;
	ret = sys_rseq(global_rseq, 31, 0, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Registration with invalid size fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EINVAL)
		goto error;


#if defined(__LP64__) && (!defined(__s390__) && !defined(__s390x__))
	/*
	 * We haven't found a reliable way to find an invalid address when
	 * running a 32bit userspace on a 64bit kernel, so only run this test
	 * on 64bit builds for the moment.
	 *
	 * Also exclude architectures that select
	 * CONFIG_ALTERNATE_USER_ADDRESS_SPACE where the kernel and userspace
	 * have their own address space and this failure can't happen.
	 */

	/* EFAULT */
	errno = 0;
	ret = sys_rseq((void *) -4096UL, 32, 0, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Registration with invalid address fails with errno set to EFAULT (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EFAULT)
		goto error;
#endif

	errno = 0;
	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Registration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret != 0 && errno != 0)
		goto error;

	/* The current thread is registered. */

	/* EBUSY */
	errno = 0;
	ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Double registration fails with errno set to EBUSY (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EBUSY)
		goto error;

	/* EPERM */
	errno = 0;
	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG + 1);
	errno_copy = errno;
	fprintf(stderr, "Unregistration with wrong RSEQ_SIG fails with errno to EPERM (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EPERM)
		goto error;

	errno = 0;
	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Unregistration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret != 0)
		goto error;

	errno = 0;
	ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
	errno_copy = errno;
	fprintf(stderr, "Double unregistration fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
	if (ret == 0 || errno_copy != EINVAL)
		goto error;

	return 0;
error:
	return -1;
}