auth-chall.c revision 162856 
1/* $OpenBSD: auth-chall.c,v 1.12 2006/08/03 03:34:41 deraadt 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__RCSID("$FreeBSD: head/crypto/openssh/auth-chall.c 162856 2006-09-30 13:38:06Z des $");
28
29#include <sys/types.h>
30
31#include <stdarg.h>
32
33#include "xmalloc.h"
34#include "key.h"
35#include "hostfile.h"
36#include "auth.h"
37#include "log.h"
38#include "servconf.h"
39
40/* limited protocol v1 interface to kbd-interactive authentication */
41
42extern KbdintDevice *devices[];
43static KbdintDevice *device;
44extern ServerOptions options;
45
46char *
47get_challenge(Authctxt *authctxt)
48{
49	char *challenge, *name, *info, **prompts;
50	u_int i, numprompts;
51	u_int *echo_on;
52
53#ifdef USE_PAM
54	if (!options.use_pam)
55		remove_kbdint_device("pam");
56#endif
57
58	device = devices[0]; /* we always use the 1st device for protocol 1 */
59	if (device == NULL)
60		return NULL;
61	if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
62		return NULL;
63	if (device->query(authctxt->kbdintctxt, &name, &info,
64	    &numprompts, &prompts, &echo_on)) {
65		device->free_ctx(authctxt->kbdintctxt);
66		authctxt->kbdintctxt = NULL;
67		return NULL;
68	}
69	if (numprompts < 1)
70		fatal("get_challenge: numprompts < 1");
71	challenge = xstrdup(prompts[0]);
72	for (i = 0; i < numprompts; i++)
73		xfree(prompts[i]);
74	xfree(prompts);
75	xfree(name);
76	xfree(echo_on);
77	xfree(info);
78
79	return (challenge);
80}
81int
82verify_response(Authctxt *authctxt, const char *response)
83{
84	char *resp[1], *name, *info, **prompts;
85	u_int i, numprompts, *echo_on;
86	int authenticated = 0;
87
88	if (device == NULL)
89		return 0;
90	if (authctxt->kbdintctxt == NULL)
91		return 0;
92	resp[0] = (char *)response;
93	switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
94	case 0: /* Success */
95		authenticated = 1;
96		break;
97	case 1: /* Postponed - retry with empty query for PAM */
98		if ((device->query(authctxt->kbdintctxt, &name, &info,
99		    &numprompts, &prompts, &echo_on)) != 0)
100			break;
101		if (numprompts == 0 &&
102		    device->respond(authctxt->kbdintctxt, 0, resp) == 0)
103			authenticated = 1;
104
105		for (i = 0; i < numprompts; i++)
106			xfree(prompts[i]);
107		xfree(prompts);
108		xfree(name);
109		xfree(echo_on);
110		xfree(info);
111		break;
112	}
113	device->free_ctx(authctxt->kbdintctxt);
114	authctxt->kbdintctxt = NULL;
115	return authenticated;
116}
117void
118abandon_challenge_response(Authctxt *authctxt)
119{
120	if (authctxt->kbdintctxt != NULL) {
121		device->free_ctx(authctxt->kbdintctxt);
122		authctxt->kbdintctxt = NULL;
123	}
124}
125