chroot.c revision 194494 
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 194494 2009-06-19 15:58:24Z brooks $");
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;
73	uid_t		uid;
74	int		ch, gids;
75	long		ngroups_max;
76
77	gid = 0;
78	uid = 0;
79	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
80		switch(ch) {
81		case 'u':
82			user = optarg;
83			if (*user == '\0')
84				usage();
85			break;
86		case 'g':
87			group = optarg;
88			if (*group == '\0')
89				usage();
90			break;
91		case 'G':
92			grouplist = optarg;
93			if (*grouplist == '\0')
94				usage();
95			break;
96		case '?':
97		default:
98			usage();
99		}
100	}
101	argc -= optind;
102	argv += optind;
103
104	if (argc < 1)
105		usage();
106
107	if (group != NULL) {
108		if (isdigit((unsigned char)*group)) {
109			gid = (gid_t)strtoul(group, &endp, 0);
110			if (*endp != '\0')
111				goto getgroup;
112		} else {
113 getgroup:
114			if ((gp = getgrnam(group)) != NULL)
115				gid = gp->gr_gid;
116			else
117				errx(1, "no such group `%s'", group);
118		}
119	}
120
121	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
122	if ((gidlist = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
123		err(1, "malloc");
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