1 /*-
2 * Copyright (c) 2005 Robert N. M. Watson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/types.h>
28 #include <sys/mman.h>
29
30 #include <err.h>
31 #include <errno.h>
32 #include <pwd.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36
37 #define NOBODY "nobody"
38
39 /*
40 * Simple exercise for the mlock() system call -- confirm that mlock() and
41 * munlock() return success on an anonymously mapped memory page when running
42 * with privilege; confirm that they fail with EPERM when running
43 * unprivileged.
44 */
45 int
main(int argc,char * argv[])46 main(int argc, char *argv[])
47 {
48 struct passwd *pwd;
49 int pagesize;
50 char *page;
51
52 if (geteuid() != 0)
53 errx(-1, "mlock must run as root");
54
55 errno = 0;
56 pwd = getpwnam(NOBODY);
57 if (pwd == NULL && errno == 0)
58 errx(-1, "getpwnam: user \"%s\" not found", NOBODY);
59 if (pwd == NULL)
60 errx(-1, "getpwnam: %s", strerror(errno));
61 if (pwd->pw_uid == 0)
62 errx(-1, "getpwnam: user \"%s\" has uid 0", NOBODY);
63
64 pagesize = getpagesize();
65 page = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
66 if (page == MAP_FAILED)
67 errx(-1, "mmap: %s", strerror(errno));
68
69 if (mlock(page, pagesize) < 0)
70 errx(-1, "mlock privileged: %s", strerror(errno));
71
72 if (munlock(page, pagesize) < 0)
73 errx(-1, "munlock privileged: %s", strerror(errno));
74
75 if (seteuid(pwd->pw_uid) < 0)
76 errx(-1, "seteuid: %s", strerror(errno));
77
78 if (mlock(page, pagesize) == 0)
79 errx(-1, "mlock unprivileged: succeeded but shouldn't have");
80 if (errno != EPERM)
81 errx(-1, "mlock unprivileged: %s", strerror(errno));
82
83 if (munlock(page, pagesize) == 0)
84 errx(-1, "munlock unprivileged: succeeded but shouldn't have");
85 if (errno != EPERM)
86 errx(-1, "munlock unprivileged: %s", strerror(errno));
87
88 return (0);
89 }
90