1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2001 Mark R V Murray
5 * All rights reserved.
6 * Copyright (c) 2001,2002 Networks Associates Technology, Inc.
7 * All rights reserved.
8 *
9 * Portions of this software were developed for the FreeBSD Project by
10 * ThinkSec AS and NAI Labs, the Security Research Division of Network
11 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
12 * ("CBOSS"), as part of the DARPA CHATS research program.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 3. The name of the author may not be used to endorse or promote
23 *    products derived from this software without specific prior written
24 *    permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#include <sys/cdefs.h>
40#define _BSD_SOURCE
41
42#include <pwd.h>
43#include <unistd.h>
44#include <syslog.h>
45
46#define PAM_SM_AUTH
47
48#include <security/pam_appl.h>
49#include <security/pam_modules.h>
50#include <security/pam_mod_misc.h>
51
52#define OPT_ALLOW_ROOT "allow_root"
53
54PAM_EXTERN int
55pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
56    int argc __unused, const char *argv[] __unused)
57{
58	struct passwd *pwd;
59	const char *luser;
60	int pam_err;
61	uid_t uid;
62
63	pam_err = pam_get_user(pamh, &luser, NULL);
64	if (pam_err != PAM_SUCCESS)
65		return (pam_err);
66	if (luser == NULL || (pwd = getpwnam(luser)) == NULL)
67		return (PAM_AUTH_ERR);
68
69	uid = getuid();
70	if (uid == 0 && !openpam_get_option(pamh, OPT_ALLOW_ROOT))
71		return (PAM_AUTH_ERR);
72
73	if (uid == (uid_t)pwd->pw_uid)
74		return (PAM_SUCCESS);
75
76	PAM_VERBOSE_ERROR("Refused; source and target users differ");
77
78	return (PAM_AUTH_ERR);
79}
80
81PAM_EXTERN int
82pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
83    int argc __unused, const char *argv[] __unused)
84{
85
86	return (PAM_SUCCESS);
87}
88
89PAM_MODULE_ENTRY("pam_self");
90