auth-chall.c revision 295367 
1/* $OpenBSD: auth-chall.c,v 1.14 2014/06/24 01:13:21 djm Exp $ */
2/*
3 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
27
28#include <sys/types.h>
29#include <stdarg.h>
30#include <stdlib.h>
31#include <stdio.h>
32
33#include "xmalloc.h"
34#include "key.h"
35#include "hostfile.h"
36#include "auth.h"
37#include "log.h"
38#include "misc.h"
39#include "servconf.h"
40
41/* limited protocol v1 interface to kbd-interactive authentication */
42
43extern KbdintDevice *devices[];
44static KbdintDevice *device;
45extern ServerOptions options;
46
47char *
48get_challenge(Authctxt *authctxt)
49{
50	char *challenge, *name, *info, **prompts;
51	u_int i, numprompts;
52	u_int *echo_on;
53
54#ifdef USE_PAM
55	if (!options.use_pam)
56		remove_kbdint_device("pam");
57#endif
58
59	device = devices[0]; /* we always use the 1st device for protocol 1 */
60	if (device == NULL)
61		return NULL;
62	if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
63		return NULL;
64	if (device->query(authctxt->kbdintctxt, &name, &info,
65	    &numprompts, &prompts, &echo_on)) {
66		device->free_ctx(authctxt->kbdintctxt);
67		authctxt->kbdintctxt = NULL;
68		return NULL;
69	}
70	if (numprompts < 1)
71		fatal("get_challenge: numprompts < 1");
72	challenge = xstrdup(prompts[0]);
73	for (i = 0; i < numprompts; i++)
74		free(prompts[i]);
75	free(prompts);
76	free(name);
77	free(echo_on);
78	free(info);
79
80	return (challenge);
81}
82int
83verify_response(Authctxt *authctxt, const char *response)
84{
85	char *resp[1], *name, *info, **prompts;
86	u_int i, numprompts, *echo_on;
87	int authenticated = 0;
88
89	if (device == NULL)
90		return 0;
91	if (authctxt->kbdintctxt == NULL)
92		return 0;
93	resp[0] = (char *)response;
94	switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
95	case 0: /* Success */
96		authenticated = 1;
97		break;
98	case 1: /* Postponed - retry with empty query for PAM */
99		if ((device->query(authctxt->kbdintctxt, &name, &info,
100		    &numprompts, &prompts, &echo_on)) != 0)
101			break;
102		if (numprompts == 0 &&
103		    device->respond(authctxt->kbdintctxt, 0, resp) == 0)
104			authenticated = 1;
105
106		for (i = 0; i < numprompts; i++)
107			free(prompts[i]);
108		free(prompts);
109		free(name);
110		free(echo_on);
111		free(info);
112		break;
113	}
114	device->free_ctx(authctxt->kbdintctxt);
115	authctxt->kbdintctxt = NULL;
116	return authenticated;
117}
118void
119abandon_challenge_response(Authctxt *authctxt)
120{
121	if (authctxt->kbdintctxt != NULL) {
122		device->free_ctx(authctxt->kbdintctxt);
123		authctxt->kbdintctxt = NULL;
124	}
125}
126