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 * $FreeBSD$ 27 */ 28 29 #include <sys/types.h> 30 #include <sys/mman.h> 31 32 #include <err.h> 33 #include <errno.h> 34 #include <pwd.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <unistd.h> 38 39 #define NOBODY "nobody" 40 41 /* 42 * Simple exercise for the mlock() system call -- confirm that mlock() and 43 * munlock() return success on an anonymously mapped memory page when running 44 * with privilege; confirm that they fail with EPERM when running 45 * unprivileged. 46 */ 47 int 48 main(int argc, char *argv[]) 49 { 50 struct passwd *pwd; 51 int pagesize; 52 char *page; 53 54 if (geteuid() != 0) 55 errx(-1, "mlock must run as root"); 56 57 errno = 0; 58 pwd = getpwnam(NOBODY); 59 if (pwd == NULL && errno == 0) 60 errx(-1, "getpwnam: user \"%s\" not found", NOBODY); 61 if (pwd == NULL) 62 errx(-1, "getpwnam: %s", strerror(errno)); 63 if (pwd->pw_uid == 0) 64 errx(-1, "getpwnam: user \"%s\" has uid 0", NOBODY); 65 66 pagesize = getpagesize(); 67 page = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0); 68 if (page == MAP_FAILED) 69 errx(-1, "mmap: %s", strerror(errno)); 70 71 if (mlock(page, pagesize) < 0) 72 errx(-1, "mlock privileged: %s", strerror(errno)); 73 74 if (munlock(page, pagesize) < 0) 75 errx(-1, "munlock privileged: %s", strerror(errno)); 76 77 if (seteuid(pwd->pw_uid) < 0) 78 errx(-1, "seteuid: %s", strerror(errno)); 79 80 if (mlock(page, pagesize) == 0) 81 errx(-1, "mlock unprivileged: succeeded but shouldn't have"); 82 if (errno != EPERM) 83 errx(-1, "mlock unprivileged: %s", strerror(errno)); 84 85 if (munlock(page, pagesize) == 0) 86 errx(-1, "munlock unprivileged: succeeded but shouldn't have"); 87 if (errno != EPERM) 88 errx(-1, "munlock unprivileged: %s", strerror(errno)); 89 90 return (0); 91 } 92