pam_opie.c revision 270125 
1/*-
2 * Copyright 2000 James Bloom
3 * All rights reserved.
4 * Based upon code Copyright 1998 Juniper Networks, Inc.
5 * Copyright (c) 2001-2003 Networks Associates Technology, Inc.
6 * All rights reserved.
7 *
8 * Portions of this software were developed for the FreeBSD Project by
9 * ThinkSec AS and NAI Labs, the Security Research Division of Network
10 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
11 * ("CBOSS"), as part of the DARPA CHATS research program.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 *    notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 *    notice, this list of conditions and the following disclaimer in the
20 *    documentation and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote
22 *    products derived from this software without specific prior written
23 *    permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD: stable/10/lib/libpam/modules/pam_opie/pam_opie.c 270125 2014-08-18 03:06:49Z ache $");
40
41#include <sys/types.h>
42#include <opie.h>
43#include <pwd.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48
49#define PAM_SM_AUTH
50
51#include <security/pam_appl.h>
52#include <security/pam_modules.h>
53#include <security/pam_mod_misc.h>
54
55#define PAM_OPT_NO_FAKE_PROMPTS	"no_fake_prompts"
56
57PAM_EXTERN int
58pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
59    int argc __unused, const char *argv[] __unused)
60{
61	struct opie opie;
62	struct passwd *pwd;
63	int retval, i;
64	const char *(promptstr[]) = { "%s\nPassword: ", "%s\nPassword [echo on]: "};
65	char challenge[OPIE_CHALLENGE_MAX + 1];
66	char principal[OPIE_PRINCIPAL_MAX];
67	const char *user;
68	char *response;
69	int style;
70
71	user = NULL;
72	if (openpam_get_option(pamh, PAM_OPT_AUTH_AS_SELF)) {
73		if ((pwd = getpwnam(getlogin())) == NULL)
74			return (PAM_AUTH_ERR);
75		user = pwd->pw_name;
76	}
77	else {
78		retval = pam_get_user(pamh, &user, NULL);
79		if (retval != PAM_SUCCESS)
80			return (retval);
81	}
82
83	PAM_LOG("Got user: %s", user);
84
85	/*
86	 * Watch out: libopie feels entitled to truncate the user name
87	 * passed to it if it's longer than OPIE_PRINCIPAL_MAX, which is
88	 * not uncommon in Windows environments.
89	 */
90	if (strlen(user) >= sizeof(principal))
91		return (PAM_AUTH_ERR);
92	strlcpy(principal, user, sizeof(principal));
93
94	/*
95	 * Don't call the OPIE atexit() handler when our program exits,
96	 * since the module has been unloaded and we will SEGV.
97	 */
98	opiedisableaeh();
99
100	/*
101	 * If the no_fake_prompts option was given, and the user
102	 * doesn't have an OPIE key, just fail rather than present the
103	 * user with a bogus OPIE challenge.
104	 */
105	if (opiechallenge(&opie, principal, challenge) != 0 &&
106	    openpam_get_option(pamh, PAM_OPT_NO_FAKE_PROMPTS))
107		return (PAM_AUTH_ERR);
108
109	/*
110	 * It doesn't make sense to use a password that has already been
111	 * typed in, since we haven't presented the challenge to the user
112	 * yet, so clear the stored password.
113	 */
114	pam_set_item(pamh, PAM_AUTHTOK, NULL);
115
116	style = PAM_PROMPT_ECHO_OFF;
117	for (i = 0; i < 2; i++) {
118		retval = pam_prompt(pamh, style, &response,
119		    promptstr[i], challenge);
120		if (retval != PAM_SUCCESS) {
121			opieunlock();
122			return (retval);
123		}
124
125		PAM_LOG("Completed challenge %d: %s", i, response);
126
127		if (response[0] != '\0')
128			break;
129
130		/* Second time round, echo the password */
131		style = PAM_PROMPT_ECHO_ON;
132	}
133
134	pam_set_item(pamh, PAM_AUTHTOK, response);
135
136	/*
137	 * Opieverify is supposed to return -1 only if an error occurs.
138	 * But it returns -1 even if the response string isn't in the form
139	 * it expects.  Thus we can't log an error and can only check for
140	 * success or lack thereof.
141	 */
142	retval = opieverify(&opie, response);
143	free(response);
144	return (retval == 0 ? PAM_SUCCESS : PAM_AUTH_ERR);
145}
146
147PAM_EXTERN int
148pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
149    int argc __unused, const char *argv[] __unused)
150{
151
152	return (PAM_SUCCESS);
153}
154
155PAM_MODULE_ENTRY("pam_opie");
156