chroot.c revision 201387 
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 201387 2010-01-02 11:05:34Z ed $");
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(int argc, char *argv[])
65{
66	struct group	*gp;
67	struct passwd	*pw;
68	char		*endp, *p;
69	const char	*shell;
70	gid_t		gid, *gidlist;
71	uid_t		uid;
72	int		ch, gids;
73	long		ngroups_max;
74
75	gid = 0;
76	uid = 0;
77	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
78		switch(ch) {
79		case 'u':
80			user = optarg;
81			if (*user == '\0')
82				usage();
83			break;
84		case 'g':
85			group = optarg;
86			if (*group == '\0')
87				usage();
88			break;
89		case 'G':
90			grouplist = optarg;
91			if (*grouplist == '\0')
92				usage();
93			break;
94		case '?':
95		default:
96			usage();
97		}
98	}
99	argc -= optind;
100	argv += optind;
101
102	if (argc < 1)
103		usage();
104
105	if (group != NULL) {
106		if (isdigit((unsigned char)*group)) {
107			gid = (gid_t)strtoul(group, &endp, 0);
108			if (*endp != '\0')
109				goto getgroup;
110		} else {
111 getgroup:
112			if ((gp = getgrnam(group)) != NULL)
113				gid = gp->gr_gid;
114			else
115				errx(1, "no such group `%s'", group);
116		}
117	}
118
119	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
120	if ((gidlist = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
121		err(1, "malloc");
122	for (gids = 0;
123	    (p = strsep(&grouplist, ",")) != NULL && gids < ngroups_max; ) {
124		if (*p == '\0')
125			continue;
126
127		if (isdigit((unsigned char)*p)) {
128			gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
129			if (*endp != '\0')
130				goto getglist;
131		} else {
132 getglist:
133			if ((gp = getgrnam(p)) != NULL)
134				gidlist[gids] = gp->gr_gid;
135			else
136				errx(1, "no such group `%s'", p);
137		}
138		gids++;
139	}
140	if (p != NULL && gids == ngroups_max)
141		errx(1, "too many supplementary groups provided");
142
143	if (user != NULL) {
144		if (isdigit((unsigned char)*user)) {
145			uid = (uid_t)strtoul(user, &endp, 0);
146			if (*endp != '\0')
147				goto getuser;
148		} else {
149 getuser:
150			if ((pw = getpwnam(user)) != NULL)
151				uid = pw->pw_uid;
152			else
153				errx(1, "no such user `%s'", user);
154		}
155	}
156
157	if (chdir(argv[0]) == -1 || chroot(".") == -1)
158		err(1, "%s", argv[0]);
159
160	if (gids && setgroups(gids, gidlist) == -1)
161		err(1, "setgroups");
162	if (group && setgid(gid) == -1)
163		err(1, "setgid");
164	if (user && setuid(uid) == -1)
165		err(1, "setuid");
166
167	if (argv[1]) {
168		execvp(argv[1], &argv[1]);
169		err(1, "%s", argv[1]);
170	}
171
172	if (!(shell = getenv("SHELL")))
173		shell = _PATH_BSHELL;
174	execlp(shell, shell, "-i", (char *)NULL);
175	err(1, "%s", shell);
176	/* NOTREACHED */
177}
178
179static void
180usage(void)
181{
182	(void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
183	    "[-u user] newroot [command]\n");
184	exit(1);
185}
186