chroot.c revision 133248 
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 * 4. 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
30#if 0
31#ifndef lint
32static const char copyright[] =
33"@(#) Copyright (c) 1988, 1993\n\
34	The Regents of the University of California.  All rights reserved.\n";
35#endif /* not lint */
36
37#ifndef lint
38static char sccsid[] = "@(#)chroot.c	8.1 (Berkeley) 6/9/93";
39#endif /* not lint */
40#endif
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: head/usr.sbin/chroot/chroot.c 133248 2004-08-07 04:19:37Z imp $");
43
44#include <sys/types.h>
45
46#include <ctype.h>
47#include <err.h>
48#include <grp.h>
49#include <limits.h>
50#include <paths.h>
51#include <pwd.h>
52#include <stdio.h>
53#include <stdlib.h>
54#include <string.h>
55#include <unistd.h>
56
57static void usage(void);
58
59char	*user;		/* user to switch to before running program */
60char	*group;		/* group to switch to ... */
61char	*grouplist;	/* group list to switch to ... */
62
63int
64main(argc, argv)
65	int argc;
66	char *argv[];
67{
68	struct group	*gp;
69	struct passwd	*pw;
70	char		*endp, *p;
71	const char	*shell;
72	gid_t		gid, gidlist[NGROUPS_MAX];
73	uid_t		uid;
74	int		ch, gids;
75
76	gid = 0;
77	uid = 0;
78	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
79		switch(ch) {
80		case 'u':
81			user = optarg;
82			if (*user == '\0')
83				usage();
84			break;
85		case 'g':
86			group = optarg;
87			if (*group == '\0')
88				usage();
89			break;
90		case 'G':
91			grouplist = optarg;
92			if (*grouplist == '\0')
93				usage();
94			break;
95		case '?':
96		default:
97			usage();
98		}
99	}
100	argc -= optind;
101	argv += optind;
102
103	if (argc < 1)
104		usage();
105
106	if (group != NULL) {
107		if (isdigit((unsigned char)*group)) {
108			gid = (gid_t)strtoul(group, &endp, 0);
109			if (*endp != '\0')
110				goto getgroup;
111		} else {
112 getgroup:
113			if ((gp = getgrnam(group)) != NULL)
114				gid = gp->gr_gid;
115			else
116				errx(1, "no such group `%s'", group);
117		}
118	}
119
120	for (gids = 0;
121	    (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
122		if (*p == '\0')
123			continue;
124
125		if (isdigit((unsigned char)*p)) {
126			gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
127			if (*endp != '\0')
128				goto getglist;
129		} else {
130 getglist:
131			if ((gp = getgrnam(p)) != NULL)
132				gidlist[gids] = gp->gr_gid;
133			else
134				errx(1, "no such group `%s'", p);
135		}
136		gids++;
137	}
138	if (p != NULL && gids == NGROUPS_MAX)
139		errx(1, "too many supplementary groups provided");
140
141	if (user != NULL) {
142		if (isdigit((unsigned char)*user)) {
143			uid = (uid_t)strtoul(user, &endp, 0);
144			if (*endp != '\0')
145				goto getuser;
146		} else {
147 getuser:
148			if ((pw = getpwnam(user)) != NULL)
149				uid = pw->pw_uid;
150			else
151				errx(1, "no such user `%s'", user);
152		}
153	}
154
155	if (chdir(argv[0]) == -1 || chroot(".") == -1)
156		err(1, "%s", argv[0]);
157
158	if (gids && setgroups(gids, gidlist) == -1)
159		err(1, "setgroups");
160	if (group && setgid(gid) == -1)
161		err(1, "setgid");
162	if (user && setuid(uid) == -1)
163		err(1, "setuid");
164
165	if (argv[1]) {
166		execvp(argv[1], &argv[1]);
167		err(1, "%s", argv[1]);
168	}
169
170	if (!(shell = getenv("SHELL")))
171		shell = _PATH_BSHELL;
172	execlp(shell, shell, "-i", (char *)NULL);
173	err(1, "%s", shell);
174	/* NOTREACHED */
175}
176
177static void
178usage()
179{
180	(void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
181	    "[-u user] newroot [command]\n");
182	exit(1);
183}
184