ptrace-syscall.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * A ptrace test for testing PTRACE_SYSEMU, PTRACE_SETREGS and
  4 * PTRACE_GETREG.  This test basically create a child process that executes
  5 * syscalls and the parent process check if it is being traced appropriated.
  6 *
  7 * This test is heavily based on tools/testing/selftests/x86/ptrace_syscall.c
  8 * test, and it was adapted to run on Powerpc by
  9 * Breno Leitao <leitao@debian.org>
 10 */
 11#define _GNU_SOURCE
 12
 13#include <sys/ptrace.h>
 14#include <sys/types.h>
 15#include <sys/wait.h>
 16#include <sys/syscall.h>
 17#include <sys/user.h>
 18#include <unistd.h>
 19#include <errno.h>
 20#include <stddef.h>
 21#include <stdio.h>
 22#include <err.h>
 23#include <string.h>
 24#include <sys/auxv.h>
 25#include "utils.h"
 26
 27/* Bitness-agnostic defines for user_regs_struct fields. */
 28#define user_syscall_nr	gpr[0]
 29#define user_arg0		gpr[3]
 30#define user_arg1		gpr[4]
 31#define user_arg2		gpr[5]
 32#define user_arg3		gpr[6]
 33#define user_arg4		gpr[7]
 34#define user_arg5		gpr[8]
 35#define user_ip		nip
 36
 37#define PTRACE_SYSEMU		0x1d
 38
 39static int nerrs;
 40
 41static void wait_trap(pid_t chld)
 42{
 43	siginfo_t si;
 44
 45	if (waitid(P_PID, chld, &si, WEXITED|WSTOPPED) != 0)
 46		err(1, "waitid");
 47	if (si.si_pid != chld)
 48		errx(1, "got unexpected pid in event\n");
 49	if (si.si_code != CLD_TRAPPED)
 50		errx(1, "got unexpected event type %d\n", si.si_code);
 51}
 52
 53static void test_ptrace_syscall_restart(void)
 54{
 55	int status;
 56	struct pt_regs regs;
 57	pid_t chld;
 58
 59	printf("[RUN]\tptrace-induced syscall restart\n");
 60
 61	chld = fork();
 62	if (chld < 0)
 63		err(1, "fork");
 64
 65	/*
 66	 * Child process is running 4 syscalls after ptrace.
 67	 *
 68	 * 1) getpid()
 69	 * 2) gettid()
 70	 * 3) tgkill() -> Send SIGSTOP
 71	 * 4) gettid() -> Where the tests will happen essentially
 72	 */
 73	if (chld == 0) {
 74		if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
 75			err(1, "PTRACE_TRACEME");
 76
 77		pid_t pid = getpid(), tid = syscall(SYS_gettid);
 78
 79		printf("\tChild will make one syscall\n");
 80		syscall(SYS_tgkill, pid, tid, SIGSTOP);
 81
 82		syscall(SYS_gettid, 10, 11, 12, 13, 14, 15);
 83		_exit(0);
 84	}
 85	/* Parent process below */
 86
 87	/* Wait for SIGSTOP sent by tgkill above. */
 88	if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
 89		err(1, "waitpid");
 90
 91	printf("[RUN]\tSYSEMU\n");
 92	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
 93		err(1, "PTRACE_SYSEMU");
 94	wait_trap(chld);
 95
 96	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
 97		err(1, "PTRACE_GETREGS");
 98
 99	/*
100	 * Ptrace trapped prior to executing the syscall, thus r3 still has
101	 * the syscall number instead of the sys_gettid() result
102	 */
103	if (regs.user_syscall_nr != SYS_gettid ||
104	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
105	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
106	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
107		printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
108			(unsigned long)regs.user_syscall_nr,
109			(unsigned long)regs.user_arg0,
110			(unsigned long)regs.user_arg1,
111			(unsigned long)regs.user_arg2,
112			(unsigned long)regs.user_arg3,
113			(unsigned long)regs.user_arg4,
114			(unsigned long)regs.user_arg5);
115		 nerrs++;
116	} else {
117		printf("[OK]\tInitial nr and args are correct\n"); }
118
119	printf("[RUN]\tRestart the syscall (ip = 0x%lx)\n",
120	       (unsigned long)regs.user_ip);
121
122	/*
123	 * Rewind to retry the same syscall again. This will basically test
124	 * the rewind process together with PTRACE_SETREGS and PTRACE_GETREGS.
125	 */
126	regs.user_ip -= 4;
127	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
128		err(1, "PTRACE_SETREGS");
129
130	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
131		err(1, "PTRACE_SYSEMU");
132	wait_trap(chld);
133
134	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
135		err(1, "PTRACE_GETREGS");
136
137	if (regs.user_syscall_nr != SYS_gettid ||
138	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
139	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
140	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
141		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
142			(unsigned long)regs.user_syscall_nr,
143			(unsigned long)regs.user_arg0,
144			(unsigned long)regs.user_arg1,
145			(unsigned long)regs.user_arg2,
146			(unsigned long)regs.user_arg3,
147			(unsigned long)regs.user_arg4,
148			(unsigned long)regs.user_arg5);
149		nerrs++;
150	} else {
151		printf("[OK]\tRestarted nr and args are correct\n");
152	}
153
154	printf("[RUN]\tChange nr and args and restart the syscall (ip = 0x%lx)\n",
155	       (unsigned long)regs.user_ip);
156
157	/*
158	 * Inject a new syscall (getpid) in the same place the previous
159	 * syscall (gettid), rewind and re-execute.
160	 */
161	regs.user_syscall_nr = SYS_getpid;
162	regs.user_arg0 = 20;
163	regs.user_arg1 = 21;
164	regs.user_arg2 = 22;
165	regs.user_arg3 = 23;
166	regs.user_arg4 = 24;
167	regs.user_arg5 = 25;
168	regs.user_ip -= 4;
169
170	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
171		err(1, "PTRACE_SETREGS");
172
173	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
174		err(1, "PTRACE_SYSEMU");
175	wait_trap(chld);
176
177	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
178		err(1, "PTRACE_GETREGS");
179
180	/* Check that ptrace stopped at the new syscall that was
181	 * injected, and guarantee that it haven't executed, i.e, user_args
182	 * contain the arguments and not the syscall return value, for
183	 * instance.
184	 */
185	if (regs.user_syscall_nr != SYS_getpid
186		|| regs.user_arg0 != 20 || regs.user_arg1 != 21
187		|| regs.user_arg2 != 22 || regs.user_arg3 != 23
188		|| regs.user_arg4 != 24 || regs.user_arg5 != 25) {
189
190		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n",
191			(unsigned long)regs.user_syscall_nr,
192			(unsigned long)regs.user_arg0,
193			(unsigned long)regs.user_arg1,
194			(unsigned long)regs.user_arg2,
195			(unsigned long)regs.user_arg3,
196			(unsigned long)regs.user_arg4,
197			(unsigned long)regs.user_arg5);
198		nerrs++;
199	} else {
200		printf("[OK]\tReplacement nr and args are correct\n");
201	}
202
203	if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
204		err(1, "PTRACE_CONT");
205
206	if (waitpid(chld, &status, 0) != chld)
207		err(1, "waitpid");
208
209	/* Guarantee that the process executed properly, returning 0 */
210	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
211		printf("[FAIL]\tChild failed\n");
212		nerrs++;
213	} else {
214		printf("[OK]\tChild exited cleanly\n");
215	}
216}
217
218int ptrace_syscall(void)
219{
220	test_ptrace_syscall_restart();
221
222	return nerrs;
223}
224
225int main(void)
226{
227	return test_harness(ptrace_syscall, "ptrace_syscall");
228}