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chroot.c revision 1.7 
      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 
     34 #include <sys/cdefs.h>
     35 #ifndef lint
     36 __COPYRIGHT("@(#) Copyright (c) 1988, 1993\n\
     37 	The Regents of the University of California.  All rights reserved.\n");
     38 #endif /* not lint */
     39 
     40 #ifndef lint
     41 #if 0
     42 static char sccsid[] = "@(#)chroot.c	8.1 (Berkeley) 6/9/93";
     43 #else
     44 __RCSID("$NetBSD: chroot.c,v 1.7 1998/10/06 03:47:51 mrg Exp $");
     45 #endif
     46 #endif /* not lint */
     47 
     48 #include <sys/param.h>
     49 
     50 #include <ctype.h>
     51 #include <err.h>
     52 #include <errno.h>
     53 #include <grp.h>
     54 #include <paths.h>
     55 #include <pwd.h>
     56 #include <stdio.h>
     57 #include <stdlib.h>
     58 #include <string.h>
     59 #include <unistd.h>
     60 
     61 int	main __P((int, char **));
     62 void	usage __P((void)) __attribute__((__noreturn__));
     63 
     64 char	*user;		/* user to switch to before running program */
     65 char	*group;		/* group to switch to ... */
     66 char	*grouplist;	/* group list to switch to ... */
     67 
     68 int
     69 main(argc, argv)
     70 	int argc;
     71 	char *argv[];
     72 {
     73 	struct group *gp;
     74 	struct passwd *pw;
     75 	char *shell, *endp, *comma;
     76 	gid_t gid = 0, gidlist[NGROUPS_MAX];
     77 	uid_t uid = 0;
     78 	int ch, gids;
     79 
     80 	while ((ch = getopt(argc, argv, "G:g:u:")) != -1)
     81 		switch(ch) {
     82 		case 'u':
     83 			user = optarg;
     84 			break;
     85 		case 'g':
     86 			group = optarg;
     87 			break;
     88 		case 'G':
     89 			grouplist = optarg;
     90 			break;
     91 		case '?':
     92 		default:
     93 			usage();
     94 		}
     95 	argc -= optind;
     96 	argv += optind;
     97 
     98 	if (argc < 1)
     99 		usage();
    100 
    101 	if (group) {
    102 		if (isdigit(*group)) {
    103 			gid = (gid_t)strtol(group, &endp, 0);
    104 			if (endp == group)
    105 				goto getgroup;
    106 		} else {
    107 getgroup:
    108 			if ((gp = getgrnam(group)))
    109 				gid = gp->gr_gid;
    110 			else
    111 				errx(1, "no such group %s", group);
    112 		}
    113 	}
    114 
    115 	for (gids = 0; grouplist; ) {
    116 		comma = strchr(grouplist, ',');
    117 
    118 		if (comma)
    119 			*comma++ = '\0';
    120 
    121 		if (isdigit(*grouplist)) {
    122 			gidlist[gids] = (gid_t)strtol(grouplist, &endp, 0);
    123 			if (endp == grouplist)
    124 				goto getglist;
    125 		} else {
    126 getglist:
    127 			if ((gp = getgrnam(grouplist)))
    128 				gidlist[gids] = gp->gr_gid;
    129 			else
    130 				errx(1, "no such group %s", group);
    131 		}
    132 		gids++;
    133 		grouplist = comma;
    134 	}
    135 
    136 	if (user) {
    137 		if (isdigit(*user)) {
    138 			uid = (uid_t)strtol(user, &endp, 0);
    139 			if (endp == user)
    140 				goto getuser;
    141 		} else {
    142 getuser:
    143 			if ((pw = getpwnam(user)))
    144 				uid = pw->pw_uid;
    145 			else
    146 				errx(1, "no such user %s", user);
    147 		}
    148 	}
    149 
    150 	if (chdir(argv[0]) || chroot("."))
    151 		err(1, "%s", argv[0]);
    152 
    153 	if (gids && setgroups(gids, gidlist) < 0)
    154 		err(1, "setgroups");
    155 	if (group && setgid(gid) < 0)
    156 		err(1, "setgid");
    157 	if (user && setuid(uid) < 0)
    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 void
    173 usage()
    174 {
    175 	(void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
    176 	    "[-u user] newroot [command]\n");
    177 	exit(1);
    178 }
    179