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 
39 static int nerrs;
40 
41 static 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 
53 static 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 
218 int ptrace_syscall(void)
219 {
220 	test_ptrace_syscall_restart();
221 
222 	return nerrs;
223 }
224 
225 int main(void)
226 {
227 	return test_harness(ptrace_syscall, "ptrace_syscall");
228 }
229