chroot.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 * 4. 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#if 0
33#ifndef lint
34static const char copyright[] =
35"@(#) Copyright (c) 1988, 1993\n\
36	The Regents of the University of California.  All rights reserved.\n";
37#endif /* not lint */
38
39#ifndef lint
40static char sccsid[] = "@(#)chroot.c	8.1 (Berkeley) 6/9/93";
41#endif /* not lint */
42#endif
43#include <sys/cdefs.h>
44__FBSDID("$FreeBSD: stable/11/usr.sbin/chroot/chroot.c 330897 2018-03-14 03:19:51Z eadler $");
45
46#include <sys/types.h>
47
48#include <ctype.h>
49#include <err.h>
50#include <grp.h>
51#include <limits.h>
52#include <paths.h>
53#include <pwd.h>
54#include <stdio.h>
55#include <stdlib.h>
56#include <string.h>
57#include <unistd.h>
58
59static void usage(void);
60
61int
62main(int argc, char *argv[])
63{
64	struct group	*gp;
65	struct passwd	*pw;
66	char		*endp, *p, *user, *group, *grouplist;
67	const char	*shell;
68	gid_t		gid, *gidlist;
69	uid_t		uid;
70	int		ch, gids;
71	long		ngroups_max;
72
73	gid = 0;
74	uid = 0;
75	user = group = grouplist = NULL;
76	while ((ch = getopt(argc, argv, "G:g:u:")) != -1) {
77		switch(ch) {
78		case 'u':
79			user = optarg;
80			if (*user == '\0')
81				usage();
82			break;
83		case 'g':
84			group = optarg;
85			if (*group == '\0')
86				usage();
87			break;
88		case 'G':
89			grouplist = optarg;
90			if (*grouplist == '\0')
91				usage();
92			break;
93		case '?':
94		default:
95			usage();
96		}
97	}
98	argc -= optind;
99	argv += optind;
100
101	if (argc < 1)
102		usage();
103
104	if (group != NULL) {
105		if (isdigit((unsigned char)*group)) {
106			gid = (gid_t)strtoul(group, &endp, 0);
107			if (*endp != '\0')
108				goto getgroup;
109		} else {
110 getgroup:
111			if ((gp = getgrnam(group)) != NULL)
112				gid = gp->gr_gid;
113			else
114				errx(1, "no such group `%s'", group);
115		}
116	}
117
118	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
119	if ((gidlist = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
120		err(1, "malloc");
121	for (gids = 0;
122	    (p = strsep(&grouplist, ",")) != NULL && gids < ngroups_max; ) {
123		if (*p == '\0')
124			continue;
125
126		if (isdigit((unsigned char)*p)) {
127			gidlist[gids] = (gid_t)strtoul(p, &endp, 0);
128			if (*endp != '\0')
129				goto getglist;
130		} else {
131 getglist:
132			if ((gp = getgrnam(p)) != NULL)
133				gidlist[gids] = gp->gr_gid;
134			else
135				errx(1, "no such group `%s'", p);
136		}
137		gids++;
138	}
139	if (p != NULL && gids == ngroups_max)
140		errx(1, "too many supplementary groups provided");
141
142	if (user != NULL) {
143		if (isdigit((unsigned char)*user)) {
144			uid = (uid_t)strtoul(user, &endp, 0);
145			if (*endp != '\0')
146				goto getuser;
147		} else {
148 getuser:
149			if ((pw = getpwnam(user)) != NULL)
150				uid = pw->pw_uid;
151			else
152				errx(1, "no such user `%s'", user);
153		}
154	}
155
156	if (chdir(argv[0]) == -1 || chroot(".") == -1)
157		err(1, "%s", argv[0]);
158
159	if (gids && setgroups(gids, gidlist) == -1)
160		err(1, "setgroups");
161	if (group && setgid(gid) == -1)
162		err(1, "setgid");
163	if (user && setuid(uid) == -1)
164		err(1, "setuid");
165
166	if (argv[1]) {
167		execvp(argv[1], &argv[1]);
168		err(1, "%s", argv[1]);
169	}
170
171	if (!(shell = getenv("SHELL")))
172		shell = _PATH_BSHELL;
173	execlp(shell, shell, "-i", (char *)NULL);
174	err(1, "%s", shell);
175	/* NOTREACHED */
176}
177
178static void
179usage(void)
180{
181	(void)fprintf(stderr, "usage: chroot [-g group] [-G group,group,...] "
182	    "[-u user] newroot [command]\n");
183	exit(1);
184}
185