1 /*
2 * Copyright (c) International Business Machines Corp., 2001
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
12 * the GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 /*
20 * DESCRIPTION
21 * Testcase to check the mprotect(2) system call.
22 *
23 * ALGORITHM
24 * Create a mapped region using mmap with READ permission.
25 * Try to write into that region in a child process using memcpy.
26 * Verify that a SIGSEGV is generated.
27 * Now change the protection to WRITE using mprotect(2).
28 * Again try to write into the mapped region.
29 * Verify that no SIGSEGV is generated.
30 *
31 * HISTORY
32 * 07/2001 Ported by Wayne Boyer
33 * 05/2002 changed over to use tst_sig instead of sigaction
34 */
35
36 #include <sys/mman.h>
37 #include <sys/wait.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <limits.h>
41 #include <stdlib.h>
42 #include "test.h"
43
44 #include "safe_macros.h"
45
46 static void sighandler(int sig);
47 static void cleanup(void);
48 static void setup(void);
49
50 char *TCID = "mprotect02";
51 int TST_TOTAL = 1;
52 static int fd, status;
53 static char file1[BUFSIZ];
54
55 static char *addr = MAP_FAILED;
56 static char buf[] = "abcdefghijklmnopqrstuvwxyz";
57
main(int ac,char ** av)58 int main(int ac, char **av)
59 {
60 int lc;
61
62 int bytes_to_write, fd;
63 unsigned int num_bytes;
64 pid_t pid;
65
66 tst_parse_opts(ac, av, NULL, NULL);
67
68 setup();
69
70 for (lc = 0; TEST_LOOPING(lc); lc++) {
71
72 tst_count = 0;
73
74 fd = SAFE_OPEN(cleanup, file1, O_RDWR | O_CREAT, 0777);
75
76 num_bytes = getpagesize();
77
78 do {
79
80 bytes_to_write = MIN(strlen(buf), num_bytes);
81
82 num_bytes -=
83 SAFE_WRITE(cleanup, 1, fd, buf, bytes_to_write);
84
85 } while (0 < num_bytes);
86
87 /* mmap the PAGESIZE bytes as read only. */
88 addr = SAFE_MMAP(cleanup, 0, sizeof(buf), PROT_READ,
89 MAP_SHARED, fd, 0);
90
91 if ((pid = FORK_OR_VFORK()) == -1)
92 tst_brkm(TBROK | TERRNO, cleanup, "fork #1 failed");
93
94 if (pid == 0) {
95 memcpy(addr, buf, strlen(buf));
96 exit(255);
97 }
98
99 SAFE_WAITPID(cleanup, pid, &status, 0);
100 if (!WIFEXITED(status))
101 tst_brkm(TBROK, cleanup, "child exited abnormally "
102 "with status: %d", status);
103 switch (status) {
104 case 255:
105 tst_brkm(TBROK, cleanup,
106 "memcpy did not generate SIGSEGV");
107 case 0:
108 tst_resm(TPASS, "got SIGSEGV as expected");
109 break;
110 default:
111 tst_brkm(TBROK, cleanup, "got unexpected signal: %d",
112 status);
113 break;
114 }
115
116 /* Change the protection to WRITE. */
117 TEST(mprotect(addr, sizeof(buf), PROT_WRITE));
118
119 if (TEST_RETURN != -1) {
120 if ((pid = FORK_OR_VFORK()) == -1)
121 tst_brkm(TBROK | TERRNO, cleanup,
122 "fork #2 failed");
123
124 if (pid == 0) {
125 memcpy(addr, buf, strlen(buf));
126 exit(0);
127 }
128
129 SAFE_WAITPID(cleanup, pid, &status, 0);
130
131 if (WIFEXITED(status) &&
132 WEXITSTATUS(status) == 0)
133 tst_resm(TPASS, "didn't get SIGSEGV");
134 else
135 tst_brkm(TBROK, cleanup,
136 "child exited abnormally");
137 } else {
138 tst_resm(TFAIL | TERRNO, "mprotect failed");
139 continue;
140 }
141
142 SAFE_MUNMAP(cleanup, addr, sizeof(buf));
143 addr = MAP_FAILED;
144
145 SAFE_CLOSE(cleanup, fd);
146
147 SAFE_UNLINK(cleanup, file1);
148
149 }
150
151 cleanup();
152 tst_exit();
153 }
154
sighandler(int sig)155 static void sighandler(int sig)
156 {
157 _exit((sig == SIGSEGV) ? 0 : sig);
158 }
159
setup(void)160 static void setup(void)
161 {
162 tst_sig(FORK, sighandler, cleanup);
163
164 TEST_PAUSE;
165
166 tst_tmpdir();
167
168 sprintf(file1, "mprotect02.tmp.%d", getpid());
169 }
170
cleanup(void)171 static void cleanup(void)
172 {
173 if (addr != MAP_FAILED) {
174 SAFE_MUNMAP(NULL, addr, sizeof(buf));
175 SAFE_CLOSE(NULL, fd);
176 }
177
178 tst_rmdir();
179 }
180