1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 * $FreeBSD$
30 */
31
32#include <sys/param.h>
33#include <sys/jail.h>
34#include <sys/socket.h>
35#include <sys/sysctl.h>
36
37#include <arpa/inet.h>
38#include <netinet/in.h>
39
40#include <err.h>
41#include <errno.h>
42#include <jail.h>
43#include <limits.h>
44#include <login_cap.h>
45#include <paths.h>
46#include <pwd.h>
47#include <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <unistd.h>
51
52extern char **environ;
53
54static void	get_user_info(const char *username, const struct passwd **pwdp,
55    login_cap_t **lcapp);
56static void	usage(void);
57
58int
59main(int argc, char *argv[])
60{
61	int jid;
62	login_cap_t *lcap = NULL;
63	int ch, clean, uflag, Uflag;
64	char *cleanenv;
65	const struct passwd *pwd = NULL;
66	const char *username, *shell, *term;
67
68	ch = clean = uflag = Uflag = 0;
69	username = NULL;
70
71	while ((ch = getopt(argc, argv, "lnu:U:")) != -1) {
72		switch (ch) {
73		case 'l':
74			clean = 1;
75			break;
76		case 'n':
77			/* Specified name, now unused */
78			break;
79		case 'u':
80			username = optarg;
81			uflag = 1;
82			break;
83		case 'U':
84			username = optarg;
85			Uflag = 1;
86			break;
87		default:
88			usage();
89		}
90	}
91	argc -= optind;
92	argv += optind;
93	if (argc < 1)
94		usage();
95	if (uflag && Uflag)
96		usage();
97	if (uflag || (clean && !Uflag))
98		/* User info from the home environment */
99		get_user_info(username, &pwd, &lcap);
100
101	/* Attach to the jail */
102	jid = jail_getid(argv[0]);
103	if (jid < 0)
104		errx(1, "%s", jail_errmsg);
105	if (jail_attach(jid) == -1)
106		err(1, "jail_attach(%d)", jid);
107	if (chdir("/") == -1)
108		err(1, "chdir(): /");
109
110	/* Set up user environment */
111	if (clean || username != NULL) {
112		if (Uflag)
113			/* User info from the jail environment */
114			get_user_info(username, &pwd, &lcap);
115		if (clean) {
116			term = getenv("TERM");
117			cleanenv = NULL;
118			environ = &cleanenv;
119			setenv("PATH", "/bin:/usr/bin", 1);
120			if (term != NULL)
121				setenv("TERM", term, 1);
122		}
123		if (setgid(pwd->pw_gid) != 0)
124			err(1, "setgid");
125		if (setusercontext(lcap, pwd, pwd->pw_uid, username
126		    ? LOGIN_SETALL & ~LOGIN_SETGROUP & ~LOGIN_SETLOGIN
127		    : LOGIN_SETPATH | LOGIN_SETENV) != 0)
128			err(1, "setusercontext");
129		login_close(lcap);
130		setenv("USER", pwd->pw_name, 1);
131		setenv("HOME", pwd->pw_dir, 1);
132		setenv("SHELL",
133		    *pwd->pw_shell ? pwd->pw_shell : _PATH_BSHELL, 1);
134		if (clean && chdir(pwd->pw_dir) < 0)
135			err(1, "chdir: %s", pwd->pw_dir);
136		endpwent();
137	}
138
139	/* Run the specified command, or the shell */
140	if (argc > 1) {
141		if (execvp(argv[1], argv + 1) < 0)
142			err(1, "execvp: %s", argv[1]);
143	} else {
144		if (!(shell = getenv("SHELL")))
145			shell = _PATH_BSHELL;
146		if (execlp(shell, shell, "-i", NULL) < 0)
147			err(1, "execlp: %s", shell);
148	}
149	exit(0);
150}
151
152static void
153get_user_info(const char *username, const struct passwd **pwdp,
154    login_cap_t **lcapp)
155{
156	uid_t uid;
157	const struct passwd *pwd;
158
159	errno = 0;
160	if (username) {
161		pwd = getpwnam(username);
162		if (pwd == NULL) {
163			if (errno)
164				err(1, "getpwnam: %s", username);
165			else
166				errx(1, "%s: no such user", username);
167		}
168	} else {
169		uid = getuid();
170		pwd = getpwuid(uid);
171		if (pwd == NULL) {
172			if (errno)
173				err(1, "getpwuid: %d", uid);
174			else
175				errx(1, "unknown uid: %d", uid);
176		}
177	}
178	*pwdp = pwd;
179	*lcapp = login_getpwclass(pwd);
180	if (*lcapp == NULL)
181		err(1, "getpwclass: %s", pwd->pw_name);
182	if (initgroups(pwd->pw_name, pwd->pw_gid) < 0)
183		err(1, "initgroups: %s", pwd->pw_name);
184}
185
186static void
187usage(void)
188{
189
190	fprintf(stderr, "%s\n",
191	    "usage: jexec [-l] [-u username | -U username] jail [command ...]");
192	exit(1);
193}
194