summaryrefslogtreecommitdiff
path: root/usr.bin/ssh/auth2-chall.c
blob: 0d170930795e43fca61570c323f707d3c6ed4b10 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
/*
 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
 * Copyright (c) 2001 Per Allansson.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "includes.h"
RCSID("$OpenBSD: auth2-chall.c,v 1.20 2002/06/30 21:59:45 deraadt Exp $");

#include "ssh2.h"
#include "auth.h"
#include "buffer.h"
#include "packet.h"
#include "xmalloc.h"
#include "dispatch.h"
#include "auth.h"
#include "log.h"

static int auth2_challenge_start(Authctxt *);
static int send_userauth_info_request(Authctxt *);
static void input_userauth_info_response(int, u_int32_t, void *);

#ifdef BSD_AUTH
extern KbdintDevice bsdauth_device;
#else
#ifdef SKEY
extern KbdintDevice skey_device;
#endif
#endif

KbdintDevice *devices[] = {
#ifdef BSD_AUTH
	&bsdauth_device,
#else
#ifdef SKEY
	&skey_device,
#endif
#endif
	NULL
};

typedef struct KbdintAuthctxt KbdintAuthctxt;
struct KbdintAuthctxt
{
	char *devices;
	void *ctxt;
	KbdintDevice *device;
	u_int nreq;
};

static KbdintAuthctxt *
kbdint_alloc(const char *devs)
{
	KbdintAuthctxt *kbdintctxt;
	Buffer b;
	int i;

	kbdintctxt = xmalloc(sizeof(KbdintAuthctxt));
	if (strcmp(devs, "") == 0) {
		buffer_init(&b);
		for (i = 0; devices[i]; i++) {
			if (buffer_len(&b) > 0)
				buffer_append(&b, ",", 1);
			buffer_append(&b, devices[i]->name,
			    strlen(devices[i]->name));
		}
		buffer_append(&b, "\0", 1);
		kbdintctxt->devices = xstrdup(buffer_ptr(&b));
		buffer_free(&b);
	} else {
		kbdintctxt->devices = xstrdup(devs);
	}
	debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
	kbdintctxt->ctxt = NULL;
	kbdintctxt->device = NULL;
	kbdintctxt->nreq = 0;

	return kbdintctxt;
}
static void
kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
{
	if (kbdintctxt->ctxt) {
		kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
		kbdintctxt->ctxt = NULL;
	}
	kbdintctxt->device = NULL;
}
static void
kbdint_free(KbdintAuthctxt *kbdintctxt)
{
	if (kbdintctxt->device)
		kbdint_reset_device(kbdintctxt);
	if (kbdintctxt->devices) {
		xfree(kbdintctxt->devices);
		kbdintctxt->devices = NULL;
	}
	xfree(kbdintctxt);
}
/* get next device */
static int
kbdint_next_device(KbdintAuthctxt *kbdintctxt)
{
	size_t len;
	char *t;
	int i;

	if (kbdintctxt->device)
		kbdint_reset_device(kbdintctxt);
	do {
		len = kbdintctxt->devices ?
		    strcspn(kbdintctxt->devices, ",") : 0;

		if (len == 0)
			break;
		for (i = 0; devices[i]; i++)
			if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
				kbdintctxt->device = devices[i];
		t = kbdintctxt->devices;
		kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
		xfree(t);
		debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
		   kbdintctxt->devices : "<empty>");
	} while (kbdintctxt->devices && !kbdintctxt->device);

	return kbdintctxt->device ? 1 : 0;
}

/*
 * try challenge-response, set authctxt->postponed if we have to
 * wait for the response.
 */
int
auth2_challenge(Authctxt *authctxt, char *devs)
{
	debug("auth2_challenge: user=%s devs=%s",
	    authctxt->user ? authctxt->user : "<nouser>",
	    devs ? devs : "<no devs>");

	if (authctxt->user == NULL || !devs)
		return 0;
	if (authctxt->kbdintctxt == NULL)
		authctxt->kbdintctxt = kbdint_alloc(devs);
	return auth2_challenge_start(authctxt);
}

/* unregister kbd-int callbacks and context */
void
auth2_challenge_stop(Authctxt *authctxt)
{
	/* unregister callback */
	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
	if (authctxt->kbdintctxt != NULL)  {
		kbdint_free(authctxt->kbdintctxt);
		authctxt->kbdintctxt = NULL;
	}
}

/* side effect: sets authctxt->postponed if a reply was sent*/
static int
auth2_challenge_start(Authctxt *authctxt)
{
	KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;

	debug2("auth2_challenge_start: devices %s",
	    kbdintctxt->devices ?  kbdintctxt->devices : "<empty>");

	if (kbdint_next_device(kbdintctxt) == 0) {
		auth2_challenge_stop(authctxt);
		return 0;
	}
	debug("auth2_challenge_start: trying authentication method '%s'",
	    kbdintctxt->device->name);

	if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
		auth2_challenge_stop(authctxt);
		return 0;
	}
	if (send_userauth_info_request(authctxt) == 0) {
		auth2_challenge_stop(authctxt);
		return 0;
	}
	dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
	    &input_userauth_info_response);

	authctxt->postponed = 1;
	return 0;
}

static int
send_userauth_info_request(Authctxt *authctxt)
{
	KbdintAuthctxt *kbdintctxt;
	char *name, *instr, **prompts;
	int i;
	u_int *echo_on;

	kbdintctxt = authctxt->kbdintctxt;
	if (kbdintctxt->device->query(kbdintctxt->ctxt,
	    &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
		return 0;

	packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
	packet_put_cstring(name);
	packet_put_cstring(instr);
	packet_put_cstring("");		/* language not used */
	packet_put_int(kbdintctxt->nreq);
	for (i = 0; i < kbdintctxt->nreq; i++) {
		packet_put_cstring(prompts[i]);
		packet_put_char(echo_on[i]);
	}
	packet_send();
	packet_write_wait();

	for (i = 0; i < kbdintctxt->nreq; i++)
		xfree(prompts[i]);
	xfree(prompts);
	xfree(echo_on);
	xfree(name);
	xfree(instr);
	return 1;
}

static void
input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	KbdintAuthctxt *kbdintctxt;
	int i, authenticated = 0, res, len;
	u_int nresp;
	char **response = NULL, *method;

	if (authctxt == NULL)
		fatal("input_userauth_info_response: no authctxt");
	kbdintctxt = authctxt->kbdintctxt;
	if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
		fatal("input_userauth_info_response: no kbdintctxt");
	if (kbdintctxt->device == NULL)
		fatal("input_userauth_info_response: no device");

	authctxt->postponed = 0;	/* reset */
	nresp = packet_get_int();
	if (nresp != kbdintctxt->nreq)
		fatal("input_userauth_info_response: wrong number of replies");
	if (nresp > 100)
		fatal("input_userauth_info_response: too many replies");
	if (nresp > 0) {
		response = xmalloc(nresp * sizeof(char *));
		for (i = 0; i < nresp; i++)
			response[i] = packet_get_string(NULL);
	}
	packet_check_eom();

	if (authctxt->valid) {
		res = kbdintctxt->device->respond(kbdintctxt->ctxt,
		    nresp, response);
	} else {
		res = -1;
	}

	for (i = 0; i < nresp; i++) {
		memset(response[i], 'r', strlen(response[i]));
		xfree(response[i]);
	}
	if (response)
		xfree(response);

	switch (res) {
	case 0:
		/* Success! */
		authenticated = 1;
		break;
	case 1:
		/* Authentication needs further interaction */
		if (send_userauth_info_request(authctxt) == 1)
			authctxt->postponed = 1;
		break;
	default:
		/* Failure! */
		break;
	}

	len = strlen("keyboard-interactive") + 2 +
		strlen(kbdintctxt->device->name);
	method = xmalloc(len);
	snprintf(method, len, "keyboard-interactive/%s",
	    kbdintctxt->device->name);

	if (!authctxt->postponed) {
		if (authenticated) {
			auth2_challenge_stop(authctxt);
		} else {
			/* start next device */
			/* may set authctxt->postponed */
			auth2_challenge_start(authctxt);
		}
	}
	userauth_finish(authctxt, authenticated, method);
	xfree(method);
}

void
privsep_challenge_enable(void)
{
#ifdef BSD_AUTH
	extern KbdintDevice mm_bsdauth_device;
#endif
#ifdef SKEY
	extern KbdintDevice mm_skey_device;
#endif
	/* As long as SSHv1 has devices[0] hard coded this is fine */
#ifdef BSD_AUTH
	devices[0] = &mm_bsdauth_device;
#else
#ifdef SKEY
	devices[0] = &mm_skey_device;
#endif
#endif
}