1/*	$OpenBSD: chroot.c,v 1.14 2015/05/19 16:05:12 millert 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/types.h>
33#include <ctype.h>
34#include <err.h>
35#include <errno.h>
36#include <grp.h>
37#include <limits.h>
38#include <login_cap.h>
39#include <paths.h>
40#include <pwd.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <unistd.h>
45
46int		main(int, char **);
47__dead void	usage(void);
48
49int
50main(int argc, char **argv)
51{
52	struct group	*grp;
53	struct passwd	*pwd;
54	login_cap_t	*lc;
55	const char	*shell;
56	char		*user, *group, *grouplist;
57	gid_t		gidlist[NGROUPS_MAX];
58	int		ch, ngids;
59	int		flags = LOGIN_SETALL & ~(LOGIN_SETLOGIN|LOGIN_SETUSER);
60
61	lc = NULL;
62	ngids = 0;
63	pwd = NULL;
64	user = grouplist = NULL;
65	while ((ch = getopt(argc, argv, "g:u:")) != -1) {
66		switch(ch) {
67		case 'u':
68			user = optarg;
69			if (*user == '\0')
70				usage();
71			break;
72		case 'g':
73			grouplist = optarg;
74			if (*grouplist == '\0')
75				usage();
76			break;
77		default:
78			usage();
79		}
80	}
81	argc -= optind;
82	argv += optind;
83
84	if (argc < 1)
85		usage();
86
87	if (user != NULL) {
88		if ((pwd = getpwnam(user)) == NULL)
89			errx(1, "no such user `%s'", user);
90		if ((lc = login_getclass(pwd->pw_class)) == NULL)
91			err(1, "unable to get login class for `%s'", user);
92	}
93
94	while ((group = strsep(&grouplist, ",")) != NULL) {
95		if (*group == '\0')
96			continue;
97
98		if (ngids == NGROUPS_MAX)
99			errx(1, "too many supplementary groups provided");
100		if ((grp = getgrnam(group)) == NULL)
101			errx(1, "no such group `%s'", group);
102		gidlist[ngids++] = grp->gr_gid;
103	}
104
105	if (ngids != 0) {
106		if (setgid(gidlist[0]) != 0)
107			err(1, "setgid");
108		if (setgroups(ngids, gidlist) != 0)
109			err(1, "setgroups");
110		flags &= ~LOGIN_SETGROUP;
111	}
112	if (lc != NULL) {
113		if (setusercontext(lc, pwd, pwd->pw_uid, flags) == -1)
114			err(1, "setusercontext");
115	}
116
117	if (chroot(argv[0]) != 0 || chdir("/") != 0)
118		err(1, "%s", argv[0]);
119
120	if (pwd != NULL) {
121		/* only set login name if we are/can be a session leader */
122		if (getsid(0) == getpid() || setsid() != -1)
123			setlogin(pwd->pw_name);
124		if (setuid(pwd->pw_uid) != 0)
125			err(1, "setuid");
126	}
127
128	if (argv[1]) {
129		execvp(argv[1], &argv[1]);
130		err(1, "%s", argv[1]);
131	}
132
133	if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
134		shell = _PATH_BSHELL;
135	execlp(shell, shell, "-i", (char *)NULL);
136	err(1, "%s", shell);
137	/* NOTREACHED */
138}
139
140__dead void
141usage(void)
142{
143	extern char *__progname;
144
145	(void)fprintf(stderr, "usage: %s [-g group,group,...] [-u user] "
146	    "newroot [command]\n", __progname);
147	exit(1);
148}
149