cachepc-linux

ptrace-syscall.c (6239B)

// SPDX-License-Identifier: GPL-2.0
/*
 * A ptrace test for testing PTRACE_SYSEMU, PTRACE_SETREGS and
 * PTRACE_GETREG.  This test basically create a child process that executes
 * syscalls and the parent process check if it is being traced appropriated.
 *
 * This test is heavily based on tools/testing/selftests/x86/ptrace_syscall.c
 * test, and it was adapted to run on Powerpc by
 * Breno Leitao <leitao@debian.org>
 */
#define _GNU_SOURCE

#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/syscall.h>
#include <sys/user.h>
#include <unistd.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <err.h>
#include <string.h>
#include <sys/auxv.h>
#include "utils.h"

/* Bitness-agnostic defines for user_regs_struct fields. */
#define user_syscall_nr	gpr[0]
#define user_arg0		gpr[3]
#define user_arg1		gpr[4]
#define user_arg2		gpr[5]
#define user_arg3		gpr[6]
#define user_arg4		gpr[7]
#define user_arg5		gpr[8]
#define user_ip		nip

#define PTRACE_SYSEMU		0x1d

static int nerrs;

static void wait_trap(pid_t chld)
{
	siginfo_t si;

	if (waitid(P_PID, chld, &si, WEXITED|WSTOPPED) != 0)
		err(1, "waitid");
	if (si.si_pid != chld)
		errx(1, "got unexpected pid in event\n");
	if (si.si_code != CLD_TRAPPED)
		errx(1, "got unexpected event type %d\n", si.si_code);
}

static void test_ptrace_syscall_restart(void)
{
	int status;
	struct pt_regs regs;
	pid_t chld;

	printf("[RUN]\tptrace-induced syscall restart\n");

	chld = fork();
	if (chld < 0)
		err(1, "fork");

	/*
	 * Child process is running 4 syscalls after ptrace.
	 *
	 * 1) getpid()
	 * 2) gettid()
	 * 3) tgkill() -> Send SIGSTOP
	 * 4) gettid() -> Where the tests will happen essentially
	 */
	if (chld == 0) {
		if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
			err(1, "PTRACE_TRACEME");

		pid_t pid = getpid(), tid = syscall(SYS_gettid);

		printf("\tChild will make one syscall\n");
		syscall(SYS_tgkill, pid, tid, SIGSTOP);

		syscall(SYS_gettid, 10, 11, 12, 13, 14, 15);
		_exit(0);
	}
	/* Parent process below */

	/* Wait for SIGSTOP sent by tgkill above. */
	if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
		err(1, "waitpid");

	printf("[RUN]\tSYSEMU\n");
	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
		err(1, "PTRACE_SYSEMU");
	wait_trap(chld);

	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
		err(1, "PTRACE_GETREGS");

	/*
	 * Ptrace trapped prior to executing the syscall, thus r3 still has
	 * the syscall number instead of the sys_gettid() result
	 */
	if (regs.user_syscall_nr != SYS_gettid ||
	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
		printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
			(unsigned long)regs.user_syscall_nr,
			(unsigned long)regs.user_arg0,
			(unsigned long)regs.user_arg1,
			(unsigned long)regs.user_arg2,
			(unsigned long)regs.user_arg3,
			(unsigned long)regs.user_arg4,
			(unsigned long)regs.user_arg5);
		 nerrs++;
	} else {
		printf("[OK]\tInitial nr and args are correct\n"); }

	printf("[RUN]\tRestart the syscall (ip = 0x%lx)\n",
	       (unsigned long)regs.user_ip);

	/*
	 * Rewind to retry the same syscall again. This will basically test
	 * the rewind process together with PTRACE_SETREGS and PTRACE_GETREGS.
	 */
	regs.user_ip -= 4;
	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
		err(1, "PTRACE_SETREGS");

	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
		err(1, "PTRACE_SYSEMU");
	wait_trap(chld);

	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
		err(1, "PTRACE_GETREGS");

	if (regs.user_syscall_nr != SYS_gettid ||
	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
			(unsigned long)regs.user_syscall_nr,
			(unsigned long)regs.user_arg0,
			(unsigned long)regs.user_arg1,
			(unsigned long)regs.user_arg2,
			(unsigned long)regs.user_arg3,
			(unsigned long)regs.user_arg4,
			(unsigned long)regs.user_arg5);
		nerrs++;
	} else {
		printf("[OK]\tRestarted nr and args are correct\n");
	}

	printf("[RUN]\tChange nr and args and restart the syscall (ip = 0x%lx)\n",
	       (unsigned long)regs.user_ip);

	/*
	 * Inject a new syscall (getpid) in the same place the previous
	 * syscall (gettid), rewind and re-execute.
	 */
	regs.user_syscall_nr = SYS_getpid;
	regs.user_arg0 = 20;
	regs.user_arg1 = 21;
	regs.user_arg2 = 22;
	regs.user_arg3 = 23;
	regs.user_arg4 = 24;
	regs.user_arg5 = 25;
	regs.user_ip -= 4;

	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
		err(1, "PTRACE_SETREGS");

	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
		err(1, "PTRACE_SYSEMU");
	wait_trap(chld);

	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
		err(1, "PTRACE_GETREGS");

	/* Check that ptrace stopped at the new syscall that was
	 * injected, and guarantee that it haven't executed, i.e, user_args
	 * contain the arguments and not the syscall return value, for
	 * instance.
	 */
	if (regs.user_syscall_nr != SYS_getpid
		|| regs.user_arg0 != 20 || regs.user_arg1 != 21
		|| regs.user_arg2 != 22 || regs.user_arg3 != 23
		|| regs.user_arg4 != 24 || regs.user_arg5 != 25) {

		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
			(unsigned long)regs.user_syscall_nr,
			(unsigned long)regs.user_arg0,
			(unsigned long)regs.user_arg1,
			(unsigned long)regs.user_arg2,
			(unsigned long)regs.user_arg3,
			(unsigned long)regs.user_arg4,
			(unsigned long)regs.user_arg5);
		nerrs++;
	} else {
		printf("[OK]\tReplacement nr and args are correct\n");
	}

	if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
		err(1, "PTRACE_CONT");

	if (waitpid(chld, &status, 0) != chld)
		err(1, "waitpid");

	/* Guarantee that the process executed properly, returning 0 */
	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
		printf("[FAIL]\tChild failed\n");
		nerrs++;
	} else {
		printf("[OK]\tChild exited cleanly\n");
	}
}

int ptrace_syscall(void)
{
	test_ptrace_syscall_restart();

	return nerrs;
}

int main(void)
{
	return test_harness(ptrace_syscall, "ptrace_syscall");
}