usr.sbin/chroot/chroot.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  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  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)chroot.c 8.1 (Berkeley) 6/9/93
  31  * $FreeBSD: src/usr.sbin/chroot/chroot.c,v 1.4.2.1 2002/03/15 22:54:59 mikeh Exp $
  32  * $DragonFly: src/usr.sbin/chroot/chroot.c,v 1.9 2004/12/22 08:59:33 dillon Exp $
  33  */
  34
  35 #include <sys/types.h>
  36
  37 #include <ctype.h>
  38 #include <err.h>
  39 #include <grp.h>
  40 #include <limits.h>
  41 #include <paths.h>
  42 #include <pwd.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47
  48 static void usage(void);
  49
  50 int
  51 main(int argc, char **argv)
  52 {
  53         struct group    *gp;
  54         struct passwd   *pw;
  55         char            *endp, *p;
  56         const char      *shell;
  57         const char      *user;          /* user to switch to before running program */
  58         const char      *group;         /* group to switch to ... */
  59         char            *grouplist;     /* group list to switch to ... */
  60         gid_t           gid, gidlist[NGROUPS_MAX];
  61         uid_t           uid;
  62         int             ch, gids;
  63
  64         user = NULL;
  65         group = NULL;
  66         grouplist = NULL;
  67
  68         gid = 0;
  69         uid = 0;
  70         while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
  71                 switch(ch) {
  72                 case 'u':
  73                         user = optarg;
  74                         if (*user == '\0')
  75                                 usage();
  76                         break;
  77                 case 'g':
  78                         group = optarg;
  79                         if (*group == '\0')
  80                                 usage();
  81                         break;
  82                 case 'G':
  83                         grouplist = optarg;
  84                         if (*grouplist == '\0')
  85                                 usage();
  86                         break;
  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(*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         for (gids = 0;
 112             (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
 113                 if (*p == '\0')
 114                         continue;
 115
 116                 if (isdigit(*p)) {
 117                         gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
 118                         if (*endp != '\0')
 119                                 goto getglist;
 120                 } else {
 121  getglist:
 122                         if ((gp = getgrnam(p)) != NULL)
 123                                 gidlist[gids] = gp->gr_gid;
 124                         else
 125                                 errx(1, "no such group `%s'", p);
 126                 }
 127                 gids++;
 128         }
 129         if (p != NULL && gids == NGROUPS_MAX)
 130                 errx(1, "too many supplementary groups provided");
 131
 132         if (user != NULL) {
 133                 if (isdigit(*user)) {
 134                         uid = (uid_t)strtoul(user, &endp, 0);
 135                         if (*endp != '\0')
 136                                 goto getuser;
 137                 } else {
 138  getuser:
 139                         if ((pw = getpwnam(user)) != NULL)
 140                                 uid = pw->pw_uid;
 141                         else
 142                                 errx(1, "no such user `%s'", user);
 143                 }
 144         }
 145
 146         if (chdir(argv[0]) == -1 || chroot(".") == -1)
 147                 err(1, "%s", argv[0]);
 148
 149         if (gids && setgroups(gids, gidlist) == -1)
 150                 err(1, "setgroups");
 151         if (group && setgid(gid) == -1)
 152                 err(1, "setgid");
 153         if (user && setuid(uid) == -1)
 154                 err(1, "setuid");
 155
 156         if (argv[1]) {
 157                 execvp(argv[1], &argv[1]);
 158                 err(1, "%s", argv[1]);
 159         }
 160
 161         if (!(shell = getenv("SHELL")))
 162                 shell = _PATH_BSHELL;
 163         execlp(shell, shell, "-i", NULL);
 164         err(1, "%s", shell);
 165         /* NOTREACHED */
 166 }
 167
 168 static void
 169 usage(void)
 170 {
 171         fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
 172             "[-u user] newroot [command]\n");
 173         exit(1);
 174 }
 175