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 /*
26 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
27 * Use is subject to license terms.
28 */
29
30 #include "includes.h"
31 RCSID("$OpenBSD: auth2-chall.c,v 1.20 2002/06/30 21:59:45 deraadt Exp $");
32
33 #include "ssh2.h"
34 #include "auth.h"
35 #include "buffer.h"
36 #include "packet.h"
37 #include "xmalloc.h"
38 #include "dispatch.h"
39 #include "auth.h"
40 #include "log.h"
41
42 #ifndef lint
43 static void auth2_challenge_start(Authctxt *);
44 static int send_userauth_info_request(Authctxt *);
45 static void input_userauth_info_response(int, u_int32_t, void *);
46
47 #ifdef BSD_AUTH
48 extern KbdintDevice bsdauth_device;
49 #else
50 #ifdef SKEY
51 extern KbdintDevice skey_device;
52 #endif
53 #endif
54
55 KbdintDevice *devices[] = {
56 #ifdef BSD_AUTH
57 &bsdauth_device,
58 #else
59 #ifdef SKEY
60 &skey_device,
61 #endif
62 #endif
63 NULL
64 };
65
66 typedef struct KbdintAuthctxt KbdintAuthctxt;
67 struct KbdintAuthctxt
68 {
69 char *devices;
70 void *ctxt;
71 KbdintDevice *device;
72 u_int nreq;
73 };
74
75 static KbdintAuthctxt *
kbdint_alloc(const char * devs)76 kbdint_alloc(const char *devs)
77 {
78 KbdintAuthctxt *kbdintctxt;
79 Buffer b;
80 int i;
81
82 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt));
83 if (strcmp(devs, "") == 0) {
84 buffer_init(&b);
85 for (i = 0; devices[i]; i++) {
86 if (buffer_len(&b) > 0)
87 buffer_append(&b, ",", 1);
88 buffer_append(&b, devices[i]->name,
89 strlen(devices[i]->name));
90 }
91 buffer_append(&b, "\0", 1);
92 kbdintctxt->devices = xstrdup(buffer_ptr(&b));
93 buffer_free(&b);
94 } else {
95 kbdintctxt->devices = xstrdup(devs);
96 }
97 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
98 kbdintctxt->ctxt = NULL;
99 kbdintctxt->device = NULL;
100 kbdintctxt->nreq = 0;
101
102 return kbdintctxt;
103 }
104 static void
kbdint_reset_device(KbdintAuthctxt * kbdintctxt)105 kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
106 {
107 if (kbdintctxt->ctxt) {
108 kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
109 kbdintctxt->ctxt = NULL;
110 }
111 kbdintctxt->device = NULL;
112 }
113 static void
kbdint_free(KbdintAuthctxt * kbdintctxt)114 kbdint_free(KbdintAuthctxt *kbdintctxt)
115 {
116 if (kbdintctxt->device)
117 kbdint_reset_device(kbdintctxt);
118 if (kbdintctxt->devices) {
119 xfree(kbdintctxt->devices);
120 kbdintctxt->devices = NULL;
121 }
122 xfree(kbdintctxt);
123 }
124 /* get next device */
125 static int
kbdint_next_device(KbdintAuthctxt * kbdintctxt)126 kbdint_next_device(KbdintAuthctxt *kbdintctxt)
127 {
128 size_t len;
129 char *t;
130 int i;
131
132 if (kbdintctxt->device)
133 kbdint_reset_device(kbdintctxt);
134 do {
135 len = kbdintctxt->devices ?
136 strcspn(kbdintctxt->devices, ",") : 0;
137
138 if (len == 0)
139 break;
140 for (i = 0; devices[i]; i++)
141 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
142 kbdintctxt->device = devices[i];
143 t = kbdintctxt->devices;
144 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
145 xfree(t);
146 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
147 kbdintctxt->devices : "<empty>");
148 } while (kbdintctxt->devices && !kbdintctxt->device);
149
150 return kbdintctxt->device ? 1 : 0;
151 }
152
153 /*
154 * try challenge-response, set authctxt->method->postponed if we have to
155 * wait for the response.
156 */
157 void
auth2_challenge(Authctxt * authctxt,char * devs)158 auth2_challenge(Authctxt *authctxt, char *devs)
159 {
160 debug("auth2_challenge: user=%s devs=%s",
161 authctxt->user ? authctxt->user : "<nouser>",
162 devs ? devs : "<no devs>");
163
164 if (authctxt->user == NULL || !devs)
165 return;
166 if (authctxt->method->method_data != NULL) {
167 auth2_challenge_abandon(authctxt);
168 authctxt->method->abandoned = 0;
169 }
170 authctxt->method->method_data = (void *) kbdint_alloc(devs);
171 auth2_challenge_start(authctxt);
172 }
173
174 /* unregister kbd-int callbacks and context */
175 static void
auth2_challenge_stop(Authctxt * authctxt)176 auth2_challenge_stop(Authctxt *authctxt)
177 {
178 /* unregister callback */
179 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
180 if (authctxt->method->method_data != NULL) {
181 kbdint_free((KbdintAuthctxt *) authctxt->method->method_data);
182 authctxt->method->method_data = NULL;
183 }
184 }
185
186 void
auth2_challenge_abandon(Authctxt * authctxt)187 auth2_challenge_abandon(Authctxt *authctxt)
188 {
189 auth2_challenge_stop(authctxt);
190 authctxt->method->abandoned = 1;
191 authctxt->method->postponed = 0;
192 authctxt->method->authenticated = 0;
193 authctxt->method->abandons++;
194 authctxt->method->attempts++;
195 }
196
197 /* side effect: sets authctxt->method->postponed if a reply was sent*/
198 static void
auth2_challenge_start(Authctxt * authctxt)199 auth2_challenge_start(Authctxt *authctxt)
200 {
201 KbdintAuthctxt *kbdintctxt = (KbdintAuthctxt *)
202 authctxt->method->method_data;
203
204 debug2("auth2_challenge_start: devices %s",
205 kbdintctxt->devices ? kbdintctxt->devices : "<empty>");
206
207 if (kbdint_next_device(kbdintctxt) == 0) {
208 auth2_challenge_stop(authctxt);
209 return;
210 }
211 debug("auth2_challenge_start: trying authentication method '%s'",
212 kbdintctxt->device->name);
213
214 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
215 auth2_challenge_stop(authctxt);
216 return;
217 }
218 if (send_userauth_info_request(authctxt) == 0) {
219 auth2_challenge_stop(authctxt);
220 return;
221 }
222 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
223 &input_userauth_info_response);
224
225 authctxt->method->postponed = 1;
226 }
227
228 static int
send_userauth_info_request(Authctxt * authctxt)229 send_userauth_info_request(Authctxt *authctxt)
230 {
231 KbdintAuthctxt *kbdintctxt;
232 char *name, *instr, **prompts;
233 int i;
234 u_int *echo_on;
235
236 kbdintctxt = (KbdintAuthctxt *) authctxt->method->method_data;
237 if (kbdintctxt->device->query(kbdintctxt->ctxt,
238 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
239 return 0;
240
241 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
242 packet_put_cstring(name);
243 packet_put_utf8_cstring(instr);
244 packet_put_cstring(""); /* language not used */
245 packet_put_int(kbdintctxt->nreq);
246 for (i = 0; i < kbdintctxt->nreq; i++) {
247 packet_put_utf8_cstring(prompts[i]);
248 packet_put_char(echo_on[i]);
249 }
250 packet_send();
251 packet_write_wait();
252
253 for (i = 0; i < kbdintctxt->nreq; i++)
254 xfree(prompts[i]);
255 xfree(prompts);
256 xfree(echo_on);
257 xfree(name);
258 xfree(instr);
259 return 1;
260 }
261
262 static void
input_userauth_info_response(int type,u_int32_t seq,void * ctxt)263 input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
264 {
265 Authctxt *authctxt = ctxt;
266 KbdintAuthctxt *kbdintctxt;
267 int i, res, len;
268 u_int nresp;
269 char **response = NULL, *method;
270
271 if (authctxt == NULL)
272 fatal("input_userauth_info_response: no authctxt");
273 kbdintctxt = (KbdintAuthctxt *) authctxt->method->method_data;
274 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
275 fatal("input_userauth_info_response: no kbdintctxt");
276 if (kbdintctxt->device == NULL)
277 fatal("input_userauth_info_response: no device");
278
279 nresp = packet_get_int();
280 if (nresp != kbdintctxt->nreq)
281 fatal("input_userauth_info_response: wrong number of replies");
282 if (nresp > 100)
283 fatal("input_userauth_info_response: too many replies");
284 if (nresp > 0) {
285 response = xmalloc(nresp * sizeof(char *));
286 for (i = 0; i < nresp; i++)
287 response[i] = packet_get_string(NULL);
288 }
289 packet_check_eom();
290
291 if (authctxt->valid) {
292 res = kbdintctxt->device->respond(kbdintctxt->ctxt,
293 nresp, response);
294 } else {
295 res = -1;
296 }
297
298 for (i = 0; i < nresp; i++) {
299 memset(response[i], 'r', strlen(response[i]));
300 xfree(response[i]);
301 }
302 if (response)
303 xfree(response);
304
305 authctxt->method->postponed = 0; /* reset */
306 switch (res) {
307 case 0:
308 /* Success! */
309 authctxt->method->authenticated = 1;
310 break;
311 case 1:
312 /* Authentication needs further interaction */
313 if (send_userauth_info_request(authctxt) == 1) {
314 authctxt->method->postponed = 1;
315 }
316 break;
317 default:
318 /* Failure! */
319 break;
320 }
321
322
323 len = strlen("keyboard-interactive") + 2 +
324 strlen(kbdintctxt->device->name);
325 method = xmalloc(len);
326 snprintf(method, len, "keyboard-interactive/%s",
327 kbdintctxt->device->name);
328
329 if (authctxt->method->authenticated || authctxt->method->abandoned) {
330 auth2_challenge_stop(authctxt);
331 } else {
332 /* start next device */
333 /* may set authctxt->method->postponed */
334 auth2_challenge_start(authctxt);
335 }
336 userauth_finish(authctxt, method);
337 xfree(method);
338 }
339
340 void
privsep_challenge_enable(void)341 privsep_challenge_enable(void)
342 {
343 #ifdef BSD_AUTH
344 extern KbdintDevice mm_bsdauth_device;
345 #endif
346 #ifdef SKEY
347 extern KbdintDevice mm_skey_device;
348 #endif
349 /* As long as SSHv1 has devices[0] hard coded this is fine */
350 #ifdef BSD_AUTH
351 devices[0] = &mm_bsdauth_device;
352 #else
353 #ifdef SKEY
354 devices[0] = &mm_skey_device;
355 #endif
356 #endif
357 }
358 #endif /* lint */
359