1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org>
5 * Copyright (c) 2008 Bjoern A. Zeeb <bz@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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#include <sys/param.h>
31#include <sys/jail.h>
32#include <sys/socket.h>
33#include <sys/sysctl.h>
34
35#include <arpa/inet.h>
36#include <netinet/in.h>
37
38#include <err.h>
39#include <errno.h>
40#include <jail.h>
41#include <limits.h>
42#include <login_cap.h>
43#include <paths.h>
44#include <pwd.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <unistd.h>
49
50extern char **environ;
51
52static void	get_user_info(const char *username, const struct passwd **pwdp,
53    login_cap_t **lcapp);
54static void	usage(void);
55
56int
57main(int argc, char *argv[])
58{
59	int jid;
60	login_cap_t *lcap = NULL;
61	int ch, clean, uflag, Uflag;
62	char *cleanenv;
63	const struct passwd *pwd = NULL;
64	const char *username, *shell, *term;
65
66	ch = clean = uflag = Uflag = 0;
67	username = NULL;
68
69	while ((ch = getopt(argc, argv, "lnu:U:")) != -1) {
70		switch (ch) {
71		case 'l':
72			clean = 1;
73			break;
74		case 'n':
75			/* Specified name, now unused */
76			break;
77		case 'u':
78			username = optarg;
79			uflag = 1;
80			break;
81		case 'U':
82			username = optarg;
83			Uflag = 1;
84			break;
85		default:
86			usage();
87		}
88	}
89	argc -= optind;
90	argv += optind;
91	if (argc < 1)
92		usage();
93	if (uflag && Uflag)
94		usage();
95	if (uflag || (clean && !Uflag))
96		/* User info from the home environment */
97		get_user_info(username, &pwd, &lcap);
98
99	/* Attach to the jail */
100	jid = jail_getid(argv[0]);
101	if (jid < 0)
102		errx(1, "%s", jail_errmsg);
103	if (jail_attach(jid) == -1)
104		err(1, "jail_attach(%d)", jid);
105	if (chdir("/") == -1)
106		err(1, "chdir(): /");
107
108	/* Set up user environment */
109	if (clean || username != NULL) {
110		if (Uflag)
111			/* User info from the jail environment */
112			get_user_info(username, &pwd, &lcap);
113		if (clean) {
114			term = getenv("TERM");
115			cleanenv = NULL;
116			environ = &cleanenv;
117			setenv("PATH", "/bin:/usr/bin", 1);
118			if (term != NULL)
119				setenv("TERM", term, 1);
120		}
121		if (setgid(pwd->pw_gid) != 0)
122			err(1, "setgid");
123		if (setusercontext(lcap, pwd, pwd->pw_uid, username
124		    ? LOGIN_SETALL & ~LOGIN_SETGROUP & ~LOGIN_SETLOGIN
125		    : LOGIN_SETPATH | LOGIN_SETENV) != 0)
126			err(1, "setusercontext");
127		login_close(lcap);
128		setenv("USER", pwd->pw_name, 1);
129		setenv("HOME", pwd->pw_dir, 1);
130		setenv("SHELL",
131		    *pwd->pw_shell ? pwd->pw_shell : _PATH_BSHELL, 1);
132		if (clean && chdir(pwd->pw_dir) < 0)
133			err(1, "chdir: %s", pwd->pw_dir);
134		endpwent();
135	}
136
137	/* Run the specified command, or the shell */
138	if (argc > 1) {
139		if (execvp(argv[1], argv + 1) < 0)
140			err(1, "execvp: %s", argv[1]);
141	} else {
142		if (!(shell = getenv("SHELL")))
143			shell = _PATH_BSHELL;
144		if (execlp(shell, shell, "-i", NULL) < 0)
145			err(1, "execlp: %s", shell);
146	}
147	exit(0);
148}
149
150static void
151get_user_info(const char *username, const struct passwd **pwdp,
152    login_cap_t **lcapp)
153{
154	uid_t uid;
155	const struct passwd *pwd;
156
157	errno = 0;
158	if (username) {
159		pwd = getpwnam(username);
160		if (pwd == NULL) {
161			if (errno)
162				err(1, "getpwnam: %s", username);
163			else
164				errx(1, "%s: no such user", username);
165		}
166	} else {
167		uid = getuid();
168		pwd = getpwuid(uid);
169		if (pwd == NULL) {
170			if (errno)
171				err(1, "getpwuid: %d", uid);
172			else
173				errx(1, "unknown uid: %d", uid);
174		}
175	}
176	*pwdp = pwd;
177	*lcapp = login_getpwclass(pwd);
178	if (*lcapp == NULL)
179		err(1, "getpwclass: %s", pwd->pw_name);
180	if (initgroups(pwd->pw_name, pwd->pw_gid) < 0)
181		err(1, "initgroups: %s", pwd->pw_name);
182}
183
184static void
185usage(void)
186{
187
188	fprintf(stderr, "%s\n",
189	    "usage: jexec [-l] [-u username | -U username] jail [command ...]");
190	exit(1);
191}
192