1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 <sys/procctl.h> 34 35 #include <ctype.h> 36 #include <err.h> 37 #include <grp.h> 38 #include <limits.h> 39 #include <paths.h> 40 #include <pwd.h> 41 #include <stdbool.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 47 static void usage(void) __dead2; 48 49 int 50 main(int argc, char *argv[]) 51 { 52 struct group *gp; 53 struct passwd *pw; 54 char *endp, *p, *user, *group, *grouplist; 55 const char *shell; 56 gid_t gid, *gidlist; 57 uid_t uid; 58 int arg, ch, error, gids; 59 long ngroups_max; 60 bool nonprivileged; 61 62 gid = 0; 63 uid = 0; 64 user = group = grouplist = NULL; 65 nonprivileged = false; 66 while ((ch = getopt(argc, argv, "G:g:u:n")) != -1) { 67 switch(ch) { 68 case 'u': 69 user = optarg; 70 if (*user == '\0') 71 usage(); 72 break; 73 case 'g': 74 group = optarg; 75 if (*group == '\0') 76 usage(); 77 break; 78 case 'G': 79 grouplist = optarg; 80 if (*grouplist == '\0') 81 usage(); 82 break; 83 case 'n': 84 nonprivileged = true; 85 break; 86 case '?': 87 default: 88 usage(); 89 } 90 } 91 argc -= optind; 92 argv += optind; 93 94 if (argc < 1) 95 usage(); 96 97 if (group != NULL) { 98 if (isdigit((unsigned char)*group)) { 99 gid = (gid_t)strtoul(group, &endp, 0); 100 if (*endp != '\0') 101 goto getgroup; 102 } else { 103 getgroup: 104 if ((gp = getgrnam(group)) != NULL) 105 gid = gp->gr_gid; 106 else 107 errx(1, "no such group `%s'", group); 108 } 109 } 110 111 ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1; 112 if ((gidlist = malloc(sizeof(gid_t) * ngroups_max)) == NULL) 113 err(1, "malloc"); 114 for (gids = 0; 115 (p = strsep(&grouplist, ",")) != NULL && gids < ngroups_max; ) { 116 if (*p == '\0') 117 continue; 118 119 if (isdigit((unsigned char)*p)) { 120 gidlist[gids] = (gid_t)strtoul(p, &endp, 0); 121 if (*endp != '\0') 122 goto getglist; 123 } else { 124 getglist: 125 if ((gp = getgrnam(p)) != NULL) 126 gidlist[gids] = gp->gr_gid; 127 else 128 errx(1, "no such group `%s'", p); 129 } 130 gids++; 131 } 132 if (p != NULL && gids == ngroups_max) 133 errx(1, "too many supplementary groups provided"); 134 135 if (user != NULL) { 136 if (isdigit((unsigned char)*user)) { 137 uid = (uid_t)strtoul(user, &endp, 0); 138 if (*endp != '\0') 139 goto getuser; 140 } else { 141 getuser: 142 if ((pw = getpwnam(user)) != NULL) 143 uid = pw->pw_uid; 144 else 145 errx(1, "no such user `%s'", user); 146 } 147 } 148 149 if (nonprivileged) { 150 arg = PROC_NO_NEW_PRIVS_ENABLE; 151 error = procctl(P_PID, getpid(), PROC_NO_NEW_PRIVS_CTL, &arg); 152 if (error != 0) 153 err(1, "procctl"); 154 } 155 156 if (chdir(argv[0]) == -1 || chroot(".") == -1) 157 err(1, "%s", argv[0]); 158 159 if (gids && setgroups(gids, gidlist) == -1) 160 err(1, "setgroups"); 161 if (group && setgid(gid) == -1) 162 err(1, "setgid"); 163 if (user && setuid(uid) == -1) 164 err(1, "setuid"); 165 166 if (argv[1]) { 167 execvp(argv[1], &argv[1]); 168 err(1, "%s", argv[1]); 169 } 170 171 if (!(shell = getenv("SHELL"))) 172 shell = _PATH_BSHELL; 173 execlp(shell, shell, "-i", (char *)NULL); 174 err(1, "%s", shell); 175 /* NOTREACHED */ 176 } 177 178 static void 179 usage(void) 180 { 181 (void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] " 182 "[-u user] [-n] newroot [command]\n"); 183 exit(1); 184 } 185