usr.sbin/chroot/chroot.c

   1 /*      $NetBSD: chroot.c,v 1.14 2007/12/15 19:44:55 perry 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/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1988, 1993\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)chroot.c    8.1 (Berkeley) 6/9/93";
  41 #else
  42 __RCSID("$NetBSD: chroot.c,v 1.14 2007/12/15 19:44:55 perry Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/param.h>
  47
  48 #include <ctype.h>
  49 #include <err.h>
  50 #include <errno.h>
  51 #include <grp.h>
  52 #include <paths.h>
  53 #include <pwd.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58
  59 int     main(int, char **);
  60 void    usage(void) __dead;
  61
  62 char    *user;          /* user to switch to before running program */
  63 char    *group;         /* group to switch to ... */
  64 char    *grouplist;     /* group list to switch to ... */
  65
  66 int
  67 main(int argc, char *argv[])
  68 {
  69         struct group    *gp;
  70         struct passwd   *pw;
  71         char            *endp, *p;
  72         const char      *shell;
  73         gid_t           gid, gidlist[NGROUPS_MAX];
  74         uid_t           uid;
  75         int             ch, gids;
  76
  77         gid = 0;
  78         uid = 0;
  79         while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
  80                 switch(ch) {
  81                 case 'u':
  82                         user = optarg;
  83                         if (*user == '\0')
  84                                 usage();
  85                         break;
  86                 case 'g':
  87                         group = optarg;
  88                         if (*group == '\0')
  89                                 usage();
  90                         break;
  91                 case 'G':
  92                         grouplist = optarg;
  93                         if (*grouplist == '\0')
  94                                 usage();
  95                         break;
  96                 case '?':
  97                 default:
  98                         usage();
  99                 }
 100         }
 101         argc -= optind;
 102         argv += optind;
 103
 104         if (argc < 1)
 105                 usage();
 106
 107         if (group != NULL) {
 108                 if (isdigit((unsigned char)*group)) {
 109                         gid = (gid_t)strtoul(group, &endp, 0);
 110                         if (*endp != '\0')
 111                                 goto getgroup;
 112                 } else {
 113  getgroup:
 114                         if ((gp = getgrnam(group)) != NULL)
 115                                 gid = gp->gr_gid;
 116                         else
 117                                 errx(1, "no such group `%s'", group);
 118                 }
 119         }
 120
 121         for (gids = 0;
 122             (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
 123                 if (*p == '\0')
 124                         continue;
 125
 126                 if (isdigit((unsigned char)*p)) {
 127                         gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
 128                         if (*endp != '\0')
 129                                 goto getglist;
 130                 } else {
 131  getglist:
 132                         if ((gp = getgrnam(p)) != NULL)
 133                                 gidlist[gids] = gp->gr_gid;
 134                         else
 135                                 errx(1, "no such group `%s'", p);
 136                 }
 137                 gids++;
 138         }
 139         if (p != NULL && gids == NGROUPS_MAX)
 140                 errx(1, "too many supplementary groups provided");
 141
 142         if (user != NULL) {
 143                 if (isdigit((unsigned char)*user)) {
 144                         uid = (uid_t)strtoul(user, &endp, 0);
 145                         if (*endp != '\0')
 146                                 goto getuser;
 147                 } else {
 148  getuser:
 149                         if ((pw = getpwnam(user)) != NULL)
 150                                 uid = pw->pw_uid;
 151                         else
 152                                 errx(1, "no such user `%s'", user);
 153                 }
 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")) == NULL)
 172                 shell = _PATH_BSHELL;
 173         execlp(shell, shell, "-i", NULL);
 174         err(1, "%s", shell);
 175         /* NOTREACHED */
 176 }
 177
 178 void
 179 usage(void)
 180 {
 181
 182         (void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
 183             "[-u user] newroot [command]\n");
 184         exit(1);
 185 }