chroot.c revision 115952 
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#if 0
35#ifndef lint
36static const char copyright[] =
37"@(#) Copyright (c) 1988, 1993\n\
38	The Regents of the University of California.  All rights reserved.\n";
39#endif /* not lint */
40
41#ifndef lint
42static char sccsid[] = "@(#)chroot.c	8.1 (Berkeley) 6/9/93";
43#endif /* not lint */
44#endif
45#include <sys/cdefs.h>
46__FBSDID("$FreeBSD: head/usr.sbin/chroot/chroot.c 115952 2003-06-07 10:56:12Z mtm $");
47
48#include <sys/types.h>
49
50#include <ctype.h>
51#include <err.h>
52#include <grp.h>
53#include <limits.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
61static void usage(void);
62
63char	*user;		/* user to switch to before running program */
64char	*group;		/* group to switch to ... */
65char	*grouplist;	/* group list to switch to ... */
66
67int
68main(argc, argv)
69	int argc;
70	char *argv[];
71{
72	struct group	*gp;
73	struct passwd	*pw;
74	char		*endp, *p;
75	const char	*shell;
76	gid_t		gid, gidlist[NGROUPS_MAX];
77	uid_t		uid;
78	int		ch, gids;
79
80	gid = 0;
81	uid = 0;
82	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
83		switch(ch) {
84		case 'u':
85			user = optarg;
86			if (*user == '\0')
87				usage();
88			break;
89		case 'g':
90			group = optarg;
91			if (*group == '\0')
92				usage();
93			break;
94		case 'G':
95			grouplist = optarg;
96			if (*grouplist == '\0')
97				usage();
98			break;
99		case '?':
100		default:
101			usage();
102		}
103	}
104	argc -= optind;
105	argv += optind;
106
107	if (argc < 1)
108		usage();
109
110	if (group != NULL) {
111		if (isdigit((unsigned char)*group)) {
112			gid = (gid_t)strtoul(group, &endp, 0);
113			if (*endp != '\0')
114				goto getgroup;
115		} else {
116 getgroup:
117			if ((gp = getgrnam(group)) != NULL)
118				gid = gp->gr_gid;
119			else
120				errx(1, "no such group `%s'", group);
121		}
122	}
123
124	for (gids = 0;
125	    (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
126		if (*p == '\0')
127			continue;
128
129		if (isdigit((unsigned char)*p)) {
130			gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
131			if (*endp != '\0')
132				goto getglist;
133		} else {
134 getglist:
135			if ((gp = getgrnam(p)) != NULL)
136				gidlist[gids] = gp->gr_gid;
137			else
138				errx(1, "no such group `%s'", p);
139		}
140		gids++;
141	}
142	if (p != NULL && gids == NGROUPS_MAX)
143		errx(1, "too many supplementary groups provided");
144
145	if (user != NULL) {
146		if (isdigit((unsigned char)*user)) {
147			uid = (uid_t)strtoul(user, &endp, 0);
148			if (*endp != '\0')
149				goto getuser;
150		} else {
151 getuser:
152			if ((pw = getpwnam(user)) != NULL)
153				uid = pw->pw_uid;
154			else
155				errx(1, "no such user `%s'", user);
156		}
157	}
158
159	if (chdir(argv[0]) == -1 || chroot(".") == -1)
160		err(1, "%s", argv[0]);
161
162	if (gids && setgroups(gids, gidlist) == -1)
163		err(1, "setgroups");
164	if (group && setgid(gid) == -1)
165		err(1, "setgid");
166	if (user && setuid(uid) == -1)
167		err(1, "setuid");
168
169	if (argv[1]) {
170		execvp(argv[1], &argv[1]);
171		err(1, "%s", argv[1]);
172	}
173
174	if (!(shell = getenv("SHELL")))
175		shell = _PATH_BSHELL;
176	execlp(shell, shell, "-i", (char *)NULL);
177	err(1, "%s", shell);
178	/* NOTREACHED */
179}
180
181static void
182usage()
183{
184	(void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
185	    "[-u user] newroot [command]\n");
186	exit(1);
187}
188