1/*	$NetBSD: chroot.c,v 1.18 2011/08/28 08:32:47 mbalmer Exp $	*/
2
3/*
4 * Copyright (c) 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#ifndef lint
34__COPYRIGHT("@(#) Copyright (c) 1988, 1993\
35 The Regents of the University of California.  All rights reserved.");
36#endif /* not lint */
37
38#ifndef lint
39#if 0
40static char sccsid[] = "@(#)chroot.c	8.1 (Berkeley) 6/9/93";
41#else
42__RCSID("$NetBSD: chroot.c,v 1.18 2011/08/28 08:32:47 mbalmer Exp $");
43#endif
44#endif /* not lint */
45
46#include <sys/param.h>
47
48#include <err.h>
49#include <errno.h>
50#include <grp.h>
51#include <paths.h>
52#include <pwd.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <inttypes.h>
56#include <string.h>
57#include <unistd.h>
58
59static void	usage(void) __dead;
60
61static int
62getnum(const char *str, uintmax_t *num)
63{
64	char *ep;
65
66	errno = 0;
67
68	*num = strtoumax(str, &ep, 0);
69	if (str[0] == '\0' || *ep != '\0') {
70		errno = EINVAL;
71		return -1;
72	}
73
74	if (errno == ERANGE && *num == UINTMAX_MAX)
75		return -1;
76
77	return 0;
78}
79
80
81static gid_t
82getgroup(const char *group)
83{
84	uintmax_t	num;
85	struct group	*gp;
86
87	if ((gp = getgrnam(group)) != NULL)
88		return gp->gr_gid;
89
90	if (getnum(group, &num) == -1)
91	    errx(1, "no such group `%s'", group);
92
93	return (gid_t)num;
94}
95
96static uid_t
97getuser(const char *user)
98{
99	uintmax_t	num;
100	struct passwd	*pw;
101
102	if ((pw = getpwnam(user)) != NULL)
103		return pw->pw_uid;
104
105	if (getnum(user, &num) == -1)
106		errx(1, "no such user `%s'", user);
107
108	return (uid_t)num;
109}
110
111int
112main(int argc, char *argv[])
113{
114	char	*user;		/* user to switch to before running program */
115	char	*group;		/* group to switch to ... */
116	char	*grouplist;	/* group list to switch to ... */
117	char		*p;
118	const char	*shell;
119	gid_t		gid, gidlist[NGROUPS_MAX];
120	uid_t		uid;
121	int		ch, gids;
122
123	user = NULL;
124	group = NULL;
125	grouplist = NULL;
126	gid = 0;
127	uid = 0;
128	gids = 0;
129	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
130		switch(ch) {
131		case 'u':
132			user = optarg;
133			if (*user == '\0')
134				usage();
135			break;
136		case 'g':
137			group = optarg;
138			if (*group == '\0')
139				usage();
140			break;
141		case 'G':
142			grouplist = optarg;
143			if (*grouplist == '\0')
144				usage();
145			break;
146		case '?':
147		default:
148			usage();
149		}
150	}
151	argc -= optind;
152	argv += optind;
153
154	if (argc < 1)
155		usage();
156
157	if (user != NULL)
158		uid = getuser(user);
159
160	if (group != NULL)
161		gid = getgroup(group);
162
163	if (grouplist != NULL) {
164		while ((p = strsep(&grouplist, ",")) != NULL) {
165			if (*p == '\0')
166				continue;
167
168			if (gids == NGROUPS_MAX)
169				errx(1,
170				    "too many supplementary groups provided");
171
172			gidlist[gids++] = getgroup(p);
173		}
174	}
175
176	if (chdir(argv[0]) == -1 || chroot(".") == -1)
177		err(1, "%s", argv[0]);
178
179	if (gids && setgroups(gids, gidlist) == -1)
180		err(1, "setgroups");
181	if (group && setgid(gid) == -1)
182		err(1, "setgid");
183	if (user && setuid(uid) == -1)
184		err(1, "setuid");
185
186	if (argv[1]) {
187		execvp(argv[1], &argv[1]);
188		err(1, "%s", argv[1]);
189	}
190
191	if ((shell = getenv("SHELL")) == NULL)
192		shell = _PATH_BSHELL;
193	execlp(shell, shell, "-i", NULL);
194	err(1, "%s", shell);
195	/* NOTREACHED */
196}
197
198static void
199usage(void)
200{
201
202	(void)fprintf(stderr, "Usage: %s [-G group,group,...] [-g group] "
203	    "[-u user] newroot [command]\n", getprogname());
204	exit(1);
205}
206