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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
  34  * @(#)chroot.c 8.1 (Berkeley) 6/9/93
  35  * $FreeBSD: src/usr.sbin/chroot/chroot.c,v 1.4.2.1 2002/03/15 22:54:59 mikeh Exp $
  36  * $DragonFly: src/usr.sbin/chroot/chroot.c,v 1.9 2004/12/22 08:59:33 dillon Exp $
  37  */
  38
  39 #include <sys/types.h>
  40
  41 #include <ctype.h>
  42 #include <err.h>
  43 #include <grp.h>
  44 #include <limits.h>
  45 #include <paths.h>
  46 #include <pwd.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <unistd.h>
  51
  52 static void usage(void);
  53
  54 int
  55 main(int argc, char **argv)
  56 {
  57         struct group    *gp;
  58         struct passwd   *pw;
  59         char            *endp, *p;
  60         const char      *shell;
  61         const char      *user;          /* user to switch to before running program */
  62         const char      *group;         /* group to switch to ... */
  63         char            *grouplist;     /* group list to switch to ... */
  64         gid_t           gid, gidlist[NGROUPS_MAX];
  65         uid_t           uid;
  66         int             ch, gids;
  67
  68         user = NULL;
  69         group = NULL;
  70         grouplist = NULL;
  71
  72         gid = 0;
  73         uid = 0;
  74         while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
  75                 switch(ch) {
  76                 case 'u':
  77                         user = optarg;
  78                         if (*user == '\0')
  79                                 usage();
  80                         break;
  81                 case 'g':
  82                         group = optarg;
  83                         if (*group == '\0')
  84                                 usage();
  85                         break;
  86                 case 'G':
  87                         grouplist = optarg;
  88                         if (*grouplist == '\0')
  89                                 usage();
  90                         break;
  91                 default:
  92                         usage();
  93                 }
  94         }
  95         argc -= optind;
  96         argv += optind;
  97
  98         if (argc < 1)
  99                 usage();
 100
 101         if (group != NULL) {
 102                 if (isdigit(*group)) {
 103                         gid = (gid_t)strtoul(group, &endp, 0);
 104                         if (*endp != '\0')
 105                                 goto getgroup;
 106                 } else {
 107  getgroup:
 108                         if ((gp = getgrnam(group)) != NULL)
 109                                 gid = gp->gr_gid;
 110                         else
 111                                 errx(1, "no such group `%s'", group);
 112                 }
 113         }
 114
 115         for (gids = 0;
 116             (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
 117                 if (*p == '\0')
 118                         continue;
 119
 120                 if (isdigit(*p)) {
 121                         gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
 122                         if (*endp != '\0')
 123                                 goto getglist;
 124                 } else {
 125  getglist:
 126                         if ((gp = getgrnam(p)) != NULL)
 127                                 gidlist[gids] = gp->gr_gid;
 128                         else
 129                                 errx(1, "no such group `%s'", p);
 130                 }
 131                 gids++;
 132         }
 133         if (p != NULL && gids == NGROUPS_MAX)
 134                 errx(1, "too many supplementary groups provided");
 135
 136         if (user != NULL) {
 137                 if (isdigit(*user)) {
 138                         uid = (uid_t)strtoul(user, &endp, 0);
 139                         if (*endp != '\0')
 140                                 goto getuser;
 141                 } else {
 142  getuser:
 143                         if ((pw = getpwnam(user)) != NULL)
 144                                 uid = pw->pw_uid;
 145                         else
 146                                 errx(1, "no such user `%s'", user);
 147                 }
 148         }
 149
 150         if (chdir(argv[0]) == -1 || chroot(".") == -1)
 151                 err(1, "%s", argv[0]);
 152
 153         if (gids && setgroups(gids, gidlist) == -1)
 154                 err(1, "setgroups");
 155         if (group && setgid(gid) == -1)
 156                 err(1, "setgid");
 157         if (user && setuid(uid) == -1)
 158                 err(1, "setuid");
 159
 160         if (argv[1]) {
 161                 execvp(argv[1], &argv[1]);
 162                 err(1, "%s", argv[1]);
 163         }
 164
 165         if (!(shell = getenv("SHELL")))
 166                 shell = _PATH_BSHELL;
 167         execlp(shell, shell, "-i", NULL);
 168         err(1, "%s", shell);
 169         /* NOTREACHED */
 170 }
 171
 172 static void
 173 usage(void)
 174 {
 175         fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
 176             "[-u user] newroot [command]\n");
 177         exit(1);
 178 }
 179