1 /* $OpenBSD: chroot.c,v 1.14 2015/05/19 16:05:12 millert Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/types.h> 33 #include <ctype.h> 34 #include <err.h> 35 #include <errno.h> 36 #include <grp.h> 37 #include <limits.h> 38 #include <login_cap.h> 39 #include <paths.h> 40 #include <pwd.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 int main(int, char **); 47 __dead void usage(void); 48 49 int 50 main(int argc, char **argv) 51 { 52 struct group *grp; 53 struct passwd *pwd; 54 login_cap_t *lc; 55 const char *shell; 56 char *user, *group, *grouplist; 57 gid_t gidlist[NGROUPS_MAX]; 58 int ch, ngids; 59 int flags = LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETUSER); 60 61 lc = NULL; 62 ngids = 0; 63 pwd = NULL; 64 user = grouplist = NULL; 65 while ((ch = getopt(argc, argv, "g:u:")) != -1) { 66 switch(ch) { 67 case 'u': 68 user = optarg; 69 if (*user == '\0') 70 usage(); 71 break; 72 case 'g': 73 grouplist = optarg; 74 if (*grouplist == '\0') 75 usage(); 76 break; 77 default: 78 usage(); 79 } 80 } 81 argc -= optind; 82 argv += optind; 83 84 if (argc < 1) 85 usage(); 86 87 if (user != NULL) { 88 if ((pwd = getpwnam(user)) == NULL) 89 errx(1, "no such user `%s'", user); 90 if ((lc = login_getclass(pwd->pw_class)) == NULL) 91 err(1, "unable to get login class for `%s'", user); 92 } 93 94 while ((group = strsep(&grouplist, ",")) != NULL) { 95 if (*group == '\0') 96 continue; 97 98 if (ngids == NGROUPS_MAX) 99 errx(1, "too many supplementary groups provided"); 100 if ((grp = getgrnam(group)) == NULL) 101 errx(1, "no such group `%s'", group); 102 gidlist[ngids++] = grp->gr_gid; 103 } 104 105 if (ngids != 0) { 106 if (setgid(gidlist[0]) != 0) 107 err(1, "setgid"); 108 if (setgroups(ngids, gidlist) != 0) 109 err(1, "setgroups"); 110 flags &= ~LOGIN_SETGROUP; 111 } 112 if (lc != NULL) { 113 if (setusercontext(lc, pwd, pwd->pw_uid, flags) == -1) 114 err(1, "setusercontext"); 115 } 116 117 if (chroot(argv[0]) != 0 || chdir("/") != 0) 118 err(1, "%s", argv[0]); 119 120 if (pwd != NULL) { 121 /* only set login name if we are/can be a session leader */ 122 if (getsid(0) == getpid() || setsid() != -1) 123 setlogin(pwd->pw_name); 124 if (setuid(pwd->pw_uid) != 0) 125 err(1, "setuid"); 126 } 127 128 if (argv[1]) { 129 execvp(argv[1], &argv[1]); 130 err(1, "%s", argv[1]); 131 } 132 133 if ((shell = getenv("SHELL")) == NULL || *shell == '\0') 134 shell = _PATH_BSHELL; 135 execlp(shell, shell, "-i", (char *)NULL); 136 err(1, "%s", shell); 137 /* NOTREACHED */ 138 } 139 140 __dead void 141 usage(void) 142 { 143 extern char *__progname; 144 145 (void)fprintf(stderr, "usage: %s [-g group,group,...] [-u user] " 146 "newroot [command]\n", __progname); 147 exit(1); 148 } 149