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
46static void sighandler(int sig);
47static void cleanup(void);
48static void setup(void);
49
50char *TCID = "mprotect02";
51int TST_TOTAL = 1;
52static int fd, status;
53static char file1[BUFSIZ];
54
55static char *addr = MAP_FAILED;
56static char buf[] = "abcdefghijklmnopqrstuvwxyz";
57
58int main(int ac, char **av)
59{
60	int lc;
61
62	int bytes_to_write, fd;
63	size_t 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, SAFE_WRITE_ALL, fd, buf,
84				bytes_to_write);
85
86		} while (0 < num_bytes);
87
88		/* mmap the PAGESIZE bytes as read only. */
89		addr = SAFE_MMAP(cleanup, 0, sizeof(buf), PROT_READ,
90				 MAP_SHARED, fd, 0);
91
92		if ((pid = FORK_OR_VFORK()) == -1)
93			tst_brkm(TBROK | TERRNO, cleanup, "fork #1 failed");
94
95		if (pid == 0) {
96			memcpy(addr, buf, strlen(buf));
97			exit(255);
98		}
99
100		SAFE_WAITPID(cleanup, pid, &status, 0);
101		if (!WIFEXITED(status))
102			tst_brkm(TBROK, cleanup, "child exited abnormally "
103				 "with status: %d", status);
104		switch (status) {
105		case 255:
106			tst_brkm(TBROK, cleanup,
107				 "memcpy did not generate SIGSEGV");
108		case 0:
109			tst_resm(TPASS, "got SIGSEGV as expected");
110			break;
111		default:
112			tst_brkm(TBROK, cleanup, "got unexpected signal: %d",
113				 status);
114			break;
115		}
116
117		/* Change the protection to WRITE. */
118		TEST(mprotect(addr, sizeof(buf), PROT_WRITE));
119
120		if (TEST_RETURN != -1) {
121			if ((pid = FORK_OR_VFORK()) == -1)
122				tst_brkm(TBROK | TERRNO, cleanup,
123					 "fork #2 failed");
124
125			if (pid == 0) {
126				memcpy(addr, buf, strlen(buf));
127				exit(0);
128			}
129
130			SAFE_WAITPID(cleanup, pid, &status, 0);
131
132			if (WIFEXITED(status) &&
133			    WEXITSTATUS(status) == 0)
134				tst_resm(TPASS, "didn't get SIGSEGV");
135			else
136				tst_brkm(TBROK, cleanup,
137					 "child exited abnormally");
138		} else {
139			tst_resm(TFAIL | TERRNO, "mprotect failed");
140			continue;
141		}
142
143		SAFE_MUNMAP(cleanup, addr, sizeof(buf));
144		addr = MAP_FAILED;
145
146		SAFE_CLOSE(cleanup, fd);
147
148		SAFE_UNLINK(cleanup, file1);
149
150	}
151
152	cleanup();
153	tst_exit();
154}
155
156static void sighandler(int sig)
157{
158	_exit((sig == SIGSEGV) ? 0 : sig);
159}
160
161static void setup(void)
162{
163	tst_sig(FORK, sighandler, cleanup);
164
165	TEST_PAUSE;
166
167	tst_tmpdir();
168
169	sprintf(file1, "mprotect02.tmp.%d", getpid());
170}
171
172static void cleanup(void)
173{
174	if (addr != MAP_FAILED) {
175		SAFE_MUNMAP(NULL, addr, sizeof(buf));
176		SAFE_CLOSE(NULL, fd);
177	}
178
179	tst_rmdir();
180}
181