1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * This software was developed for the FreeBSD Project by ThinkSec AS and
8 * NAI Labs, the Security Research Division of Network Associates, Inc.
9 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
10 * DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. The name of the author may not be used to endorse or promote
21 *    products derived from this software without specific prior written
22 *    permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#include <sys/param.h>
38
39#include <pwd.h>
40#include <stdio.h>
41#include <string.h>
42#include <unistd.h>
43
44#define PAM_SM_SESSION
45
46#include <security/pam_appl.h>
47#include <security/pam_modules.h>
48#include <security/openpam.h>
49
50PAM_EXTERN int
51pam_sm_open_session(pam_handle_t *pamh, int flags __unused,
52    int argc __unused, const char *argv[] __unused)
53{
54	const char *dir, *end, *cwd, *user;
55	struct passwd *pwd;
56	char buf[PATH_MAX];
57
58	if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS ||
59	    user == NULL || (pwd = getpwnam(user)) == NULL)
60		return (PAM_SESSION_ERR);
61	if (pwd->pw_uid == 0 && !openpam_get_option(pamh, "also_root"))
62		return (PAM_SUCCESS);
63	if (pwd->pw_dir == NULL)
64		return (PAM_SESSION_ERR);
65	if ((end = strstr(pwd->pw_dir, "/./")) != NULL) {
66		if (snprintf(buf, sizeof(buf), "%.*s",
67		    (int)(end - pwd->pw_dir), pwd->pw_dir) > (int)sizeof(buf)) {
68			openpam_log(PAM_LOG_ERROR,
69			    "%s's home directory is too long", user);
70			return (PAM_SESSION_ERR);
71		}
72		dir = buf;
73		cwd = end + 2;
74	} else if ((dir = openpam_get_option(pamh, "dir")) != NULL) {
75		if ((cwd = openpam_get_option(pamh, "cwd")) == NULL)
76			cwd = "/";
77	} else {
78		if (openpam_get_option(pamh, "always")) {
79			openpam_log(PAM_LOG_ERROR,
80			    "%s has no chroot directory", user);
81			return (PAM_SESSION_ERR);
82		}
83		return (PAM_SUCCESS);
84	}
85
86	openpam_log(PAM_LOG_DEBUG, "chrooting %s to %s", dir, user);
87
88	if (chroot(dir) == -1) {
89		openpam_log(PAM_LOG_ERROR, "chroot(): %m");
90		return (PAM_SESSION_ERR);
91	}
92	if (chdir(cwd) == -1) {
93		openpam_log(PAM_LOG_ERROR, "chdir(): %m");
94		return (PAM_SESSION_ERR);
95	}
96	pam_setenv(pamh, "HOME", cwd, 1);
97	return (PAM_SUCCESS);
98}
99
100PAM_EXTERN int
101pam_sm_close_session(pam_handle_t *pamh __unused, int flags __unused,
102    int argc __unused, const char *argv[] __unused)
103{
104
105	return (PAM_SUCCESS);
106}
107
108PAM_MODULE_ENTRY("pam_chroot");
109