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3c0ef626 1/*
2 * Copyright (c) 2001 Markus Friedl. All rights reserved.
3 * Copyright (c) 2001 Per Allansson. 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#include "includes.h"
41b2f314 26RCSID("$OpenBSD: auth2-chall.c,v 1.20 2002/06/30 21:59:45 deraadt Exp $");
3c0ef626 27
28#include "ssh2.h"
29#include "auth.h"
e9a17296 30#include "buffer.h"
3c0ef626 31#include "packet.h"
32#include "xmalloc.h"
33#include "dispatch.h"
34#include "auth.h"
35#include "log.h"
36
37static int auth2_challenge_start(Authctxt *);
38static int send_userauth_info_request(Authctxt *);
e9a17296 39static void input_userauth_info_response(int, u_int32_t, void *);
3c0ef626 40
41#ifdef BSD_AUTH
42extern KbdintDevice bsdauth_device;
43#else
44#ifdef SKEY
45extern KbdintDevice skey_device;
46#endif
47#endif
48
49KbdintDevice *devices[] = {
50#ifdef BSD_AUTH
51 &bsdauth_device,
52#else
53#ifdef SKEY
54 &skey_device,
55#endif
56#endif
57 NULL
58};
59
60typedef struct KbdintAuthctxt KbdintAuthctxt;
61struct KbdintAuthctxt
62{
63 char *devices;
64 void *ctxt;
65 KbdintDevice *device;
680cee3b 66 u_int nreq;
3c0ef626 67};
68
69static KbdintAuthctxt *
70kbdint_alloc(const char *devs)
71{
72 KbdintAuthctxt *kbdintctxt;
e9a17296 73 Buffer b;
3c0ef626 74 int i;
3c0ef626 75
76 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt));
77 if (strcmp(devs, "") == 0) {
e9a17296 78 buffer_init(&b);
3c0ef626 79 for (i = 0; devices[i]; i++) {
e9a17296 80 if (buffer_len(&b) > 0)
81 buffer_append(&b, ",", 1);
82 buffer_append(&b, devices[i]->name,
83 strlen(devices[i]->name));
3c0ef626 84 }
e9a17296 85 buffer_append(&b, "\0", 1);
86 kbdintctxt->devices = xstrdup(buffer_ptr(&b));
87 buffer_free(&b);
3c0ef626 88 } else {
89 kbdintctxt->devices = xstrdup(devs);
90 }
e9a17296 91 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
3c0ef626 92 kbdintctxt->ctxt = NULL;
93 kbdintctxt->device = NULL;
680cee3b 94 kbdintctxt->nreq = 0;
3c0ef626 95
96 return kbdintctxt;
97}
98static void
99kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
100{
101 if (kbdintctxt->ctxt) {
102 kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
103 kbdintctxt->ctxt = NULL;
104 }
105 kbdintctxt->device = NULL;
106}
107static void
108kbdint_free(KbdintAuthctxt *kbdintctxt)
109{
110 if (kbdintctxt->device)
111 kbdint_reset_device(kbdintctxt);
112 if (kbdintctxt->devices) {
113 xfree(kbdintctxt->devices);
114 kbdintctxt->devices = NULL;
115 }
116 xfree(kbdintctxt);
117}
118/* get next device */
119static int
120kbdint_next_device(KbdintAuthctxt *kbdintctxt)
121{
122 size_t len;
123 char *t;
124 int i;
125
126 if (kbdintctxt->device)
127 kbdint_reset_device(kbdintctxt);
128 do {
129 len = kbdintctxt->devices ?
130 strcspn(kbdintctxt->devices, ",") : 0;
131
132 if (len == 0)
133 break;
134 for (i = 0; devices[i]; i++)
135 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
136 kbdintctxt->device = devices[i];
137 t = kbdintctxt->devices;
138 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
139 xfree(t);
140 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
141 kbdintctxt->devices : "<empty>");
142 } while (kbdintctxt->devices && !kbdintctxt->device);
143
144 return kbdintctxt->device ? 1 : 0;
145}
146
147/*
148 * try challenge-response, set authctxt->postponed if we have to
149 * wait for the response.
150 */
151int
152auth2_challenge(Authctxt *authctxt, char *devs)
153{
154 debug("auth2_challenge: user=%s devs=%s",
155 authctxt->user ? authctxt->user : "<nouser>",
156 devs ? devs : "<no devs>");
157
158 if (authctxt->user == NULL || !devs)
159 return 0;
e9a17296 160 if (authctxt->kbdintctxt == NULL)
3c0ef626 161 authctxt->kbdintctxt = kbdint_alloc(devs);
162 return auth2_challenge_start(authctxt);
163}
164
e9a17296 165/* unregister kbd-int callbacks and context */
166void
167auth2_challenge_stop(Authctxt *authctxt)
168{
169 /* unregister callback */
170 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
171 if (authctxt->kbdintctxt != NULL) {
172 kbdint_free(authctxt->kbdintctxt);
173 authctxt->kbdintctxt = NULL;
174 }
175}
176
3c0ef626 177/* side effect: sets authctxt->postponed if a reply was sent*/
178static int
179auth2_challenge_start(Authctxt *authctxt)
180{
181 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;
182
183 debug2("auth2_challenge_start: devices %s",
184 kbdintctxt->devices ? kbdintctxt->devices : "<empty>");
185
186 if (kbdint_next_device(kbdintctxt) == 0) {
e9a17296 187 auth2_challenge_stop(authctxt);
3c0ef626 188 return 0;
189 }
190 debug("auth2_challenge_start: trying authentication method '%s'",
191 kbdintctxt->device->name);
192
193 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
e9a17296 194 auth2_challenge_stop(authctxt);
3c0ef626 195 return 0;
196 }
197 if (send_userauth_info_request(authctxt) == 0) {
e9a17296 198 auth2_challenge_stop(authctxt);
3c0ef626 199 return 0;
200 }
201 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
202 &input_userauth_info_response);
203
204 authctxt->postponed = 1;
205 return 0;
206}
207
208static int
209send_userauth_info_request(Authctxt *authctxt)
210{
211 KbdintAuthctxt *kbdintctxt;
212 char *name, *instr, **prompts;
213 int i;
680cee3b 214 u_int *echo_on;
3c0ef626 215
216 kbdintctxt = authctxt->kbdintctxt;
217 if (kbdintctxt->device->query(kbdintctxt->ctxt,
680cee3b 218 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
3c0ef626 219 return 0;
220
221 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
222 packet_put_cstring(name);
223 packet_put_cstring(instr);
f5799ae1 224 packet_put_cstring(""); /* language not used */
680cee3b 225 packet_put_int(kbdintctxt->nreq);
226 for (i = 0; i < kbdintctxt->nreq; i++) {
3c0ef626 227 packet_put_cstring(prompts[i]);
228 packet_put_char(echo_on[i]);
229 }
230 packet_send();
231 packet_write_wait();
232
680cee3b 233 for (i = 0; i < kbdintctxt->nreq; i++)
3c0ef626 234 xfree(prompts[i]);
235 xfree(prompts);
236 xfree(echo_on);
237 xfree(name);
238 xfree(instr);
239 return 1;
240}
241
242static void
e9a17296 243input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
3c0ef626 244{
245 Authctxt *authctxt = ctxt;
246 KbdintAuthctxt *kbdintctxt;
247 int i, authenticated = 0, res, len;
248 u_int nresp;
249 char **response = NULL, *method;
250
251 if (authctxt == NULL)
252 fatal("input_userauth_info_response: no authctxt");
253 kbdintctxt = authctxt->kbdintctxt;
254 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
255 fatal("input_userauth_info_response: no kbdintctxt");
256 if (kbdintctxt->device == NULL)
257 fatal("input_userauth_info_response: no device");
258
259 authctxt->postponed = 0; /* reset */
260 nresp = packet_get_int();
680cee3b 261 if (nresp != kbdintctxt->nreq)
262 fatal("input_userauth_info_response: wrong number of replies");
263 if (nresp > 100)
264 fatal("input_userauth_info_response: too many replies");
3c0ef626 265 if (nresp > 0) {
41b2f314 266 response = xmalloc(nresp * sizeof(char *));
3c0ef626 267 for (i = 0; i < nresp; i++)
268 response[i] = packet_get_string(NULL);
269 }
e9a17296 270 packet_check_eom();
3c0ef626 271
272 if (authctxt->valid) {
273 res = kbdintctxt->device->respond(kbdintctxt->ctxt,
274 nresp, response);
275 } else {
276 res = -1;
277 }
278
279 for (i = 0; i < nresp; i++) {
280 memset(response[i], 'r', strlen(response[i]));
281 xfree(response[i]);
282 }
283 if (response)
284 xfree(response);
285
286 switch (res) {
287 case 0:
288 /* Success! */
289 authenticated = 1;
290 break;
291 case 1:
292 /* Authentication needs further interaction */
e9a17296 293 if (send_userauth_info_request(authctxt) == 1)
294 authctxt->postponed = 1;
3c0ef626 295 break;
296 default:
297 /* Failure! */
298 break;
299 }
300
301 len = strlen("keyboard-interactive") + 2 +
302 strlen(kbdintctxt->device->name);
303 method = xmalloc(len);
e9a17296 304 snprintf(method, len, "keyboard-interactive/%s",
305 kbdintctxt->device->name);
3c0ef626 306
307 if (!authctxt->postponed) {
3c0ef626 308 if (authenticated) {
e9a17296 309 auth2_challenge_stop(authctxt);
3c0ef626 310 } else {
311 /* start next device */
312 /* may set authctxt->postponed */
313 auth2_challenge_start(authctxt);
314 }
315 }
316 userauth_finish(authctxt, authenticated, method);
317 xfree(method);
318}
700318f3 319
320void
321privsep_challenge_enable(void)
322{
323#ifdef BSD_AUTH
324 extern KbdintDevice mm_bsdauth_device;
325#endif
326#ifdef SKEY
327 extern KbdintDevice mm_skey_device;
328#endif
329 /* As long as SSHv1 has devices[0] hard coded this is fine */
330#ifdef BSD_AUTH
331 devices[0] = &mm_bsdauth_device;
332#else
333#ifdef SKEY
334 devices[0] = &mm_skey_device;
335#endif
336#endif
337}
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