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 * NAME
21 * mprotect03.c
22 *
23 * DESCRIPTION
24 * Testcase to check the mprotect(2) system call.
25 *
26 * ALGORITHM
27 * Create a shared mapped file region with PROT_READ | PROT_WRITE
28 * using the mmap(2) call. Then, use mprotect(2) to disable the
29 * write permission on the mapped region. Then, attempt to write to
30 * the mapped region using memcpy(). This would generate a sigsegv.
31 * Since the sigsegv is generated, this needs to be done in a child
32 * process (as sigsegv would repeatedly be generated). The testcase
33 * succeeds only when this sigsegv is generated while attempting to
34 * memcpy() on a shared region with only read permission.
35 *
36 * HISTORY
37 * 07/2001 Ported by Wayne Boyer
38 * 05/2002 changed over to use tst_sig instead of sigaction
39 */
40
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <sys/mman.h>
44 #include <limits.h>
45 #include <signal.h>
46 #include <sys/wait.h>
47 #include "test.h"
48
49 #include "safe_macros.h"
50
51 #ifndef PAGESIZE
52 #define PAGESIZE 4096
53 #endif
54 #define FAILED 1
55
56 static void cleanup(void);
57 static void setup(void);
58
59 char *TCID = "mprotect03";
60 int TST_TOTAL = 1;
61 int status;
62 char file1[BUFSIZ];
63
main(int ac,char ** av)64 int main(int ac, char **av)
65 {
66 int lc;
67
68 char *addr;
69 int fd, pid;
70 char *buf = "abcdefghijklmnopqrstuvwxyz";
71
72 tst_parse_opts(ac, av, NULL, NULL);
73
74 setup();
75
76 for (lc = 0; TEST_LOOPING(lc); lc++) {
77 tst_count = 0;
78
79 if ((fd = open(file1, O_RDWR | O_CREAT, 0777)) < 0)
80 tst_brkm(TBROK, cleanup, "open failed");
81
82 SAFE_WRITE(cleanup, 1, fd, buf, strlen(buf));
83
84 /*
85 * mmap the PAGESIZE bytes as read only.
86 */
87 addr = mmap(0, strlen(buf), PROT_READ | PROT_WRITE, MAP_SHARED,
88 fd, 0);
89 if (addr == MAP_FAILED)
90 tst_brkm(TBROK, cleanup, "mmap failed");
91
92 /*
93 * Try to change the protection to WRITE.
94 */
95 TEST(mprotect(addr, strlen(buf), PROT_READ));
96
97 if (TEST_RETURN != -1) {
98 if ((pid = FORK_OR_VFORK()) == -1) {
99 tst_brkm(TBROK, cleanup, "fork failed");
100 }
101
102 if (pid == 0) {
103 memcpy(addr, buf, strlen(buf));
104 tst_resm(TINFO, "memcpy() did "
105 "not generate SIGSEGV");
106 exit(1);
107 }
108
109 waitpid(pid, &status, 0);
110 if (WEXITSTATUS(status) != 0) {
111 tst_resm(TFAIL, "child returned "
112 "unexpected status");
113 } else {
114 tst_resm(TPASS, "SIGSEGV generated "
115 "as expected");
116 }
117 } else {
118 tst_resm(TFAIL, "mprotect failed "
119 "unexpectedly, errno: %d", errno);
120 }
121
122 /* clean up things in case we are looping */
123 SAFE_MUNMAP(cleanup, addr, strlen(buf));
124 SAFE_CLOSE(cleanup, fd);
125 SAFE_UNLINK(cleanup, file1);
126 }
127
128 cleanup();
129 tst_exit();
130 }
131
sighandler(int sig)132 static void sighandler(int sig)
133 {
134 if (sig == SIGSEGV) {
135 tst_resm(TINFO, "received signal: SIGSEGV");
136 tst_exit();
137 } else
138 tst_brkm(TBROK, 0, "Unexpected signal %d received.", sig);
139 }
140
setup(void)141 static void setup(void)
142 {
143 tst_sig(FORK, sighandler, NULL);
144
145 TEST_PAUSE;
146
147 tst_tmpdir();
148
149 sprintf(file1, "mprotect03.tmp.%d", getpid());
150 }
151
cleanup(void)152 static void cleanup(void)
153 {
154 tst_rmdir();
155 }
156