xref: /openbsd-src/lib/libssl/d1_lib.c (revision ffcef06798eb7b98532e76a80212f0772bebc4f6)
1 /* $OpenBSD: d1_lib.c,v 1.59 2021/08/30 19:12:25 jsing Exp $ */
2 /*
3  * DTLS implementation written by Nagendra Modadugu
4  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
5  */
6 /* ====================================================================
7  * Copyright (c) 1999-2005 The OpenSSL Project.  All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in
18  *    the documentation and/or other materials provided with the
19  *    distribution.
20  *
21  * 3. All advertising materials mentioning features or use of this
22  *    software must display the following acknowledgment:
23  *    "This product includes software developed by the OpenSSL Project
24  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
25  *
26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27  *    endorse or promote products derived from this software without
28  *    prior written permission. For written permission, please contact
29  *    openssl-core@OpenSSL.org.
30  *
31  * 5. Products derived from this software may not be called "OpenSSL"
32  *    nor may "OpenSSL" appear in their names without prior written
33  *    permission of the OpenSSL Project.
34  *
35  * 6. Redistributions of any form whatsoever must retain the following
36  *    acknowledgment:
37  *    "This product includes software developed by the OpenSSL Project
38  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51  * OF THE POSSIBILITY OF SUCH DAMAGE.
52  * ====================================================================
53  *
54  * This product includes cryptographic software written by Eric Young
55  * (eay@cryptsoft.com).  This product includes software written by Tim
56  * Hudson (tjh@cryptsoft.com).
57  *
58  */
59 
60 #include <sys/types.h>
61 #include <sys/socket.h>
62 #include <sys/time.h>
63 
64 #include <netinet/in.h>
65 
66 #include <stdio.h>
67 
68 #include <openssl/objects.h>
69 
70 #include "dtls_locl.h"
71 #include "pqueue.h"
72 #include "ssl_locl.h"
73 
74 void dtls1_hm_fragment_free(hm_fragment *frag);
75 
76 static int dtls1_listen(SSL *s, struct sockaddr *client);
77 
78 int
79 dtls1_new(SSL *s)
80 {
81 	if (!ssl3_new(s))
82 		goto err;
83 
84 	if ((s->d1 = calloc(1, sizeof(*s->d1))) == NULL)
85 		goto err;
86 	if ((s->d1->internal = calloc(1, sizeof(*s->d1->internal))) == NULL)
87 		goto err;
88 
89 	if ((s->d1->internal->unprocessed_rcds.q = pqueue_new()) == NULL)
90 		goto err;
91 	if ((s->d1->internal->buffered_messages = pqueue_new()) == NULL)
92 		goto err;
93 	if ((s->d1->sent_messages = pqueue_new()) == NULL)
94 		goto err;
95 	if ((s->d1->internal->buffered_app_data.q = pqueue_new()) == NULL)
96 		goto err;
97 
98 	if (s->server)
99 		s->d1->internal->cookie_len = sizeof(D1I(s)->cookie);
100 
101 	s->method->ssl_clear(s);
102 	return (1);
103 
104  err:
105 	dtls1_free(s);
106 	return (0);
107 }
108 
109 static void
110 dtls1_drain_records(pqueue queue)
111 {
112 	pitem *item;
113 	DTLS1_RECORD_DATA_INTERNAL *rdata;
114 
115 	if (queue == NULL)
116 		return;
117 
118 	while ((item = pqueue_pop(queue)) != NULL) {
119 		rdata = (DTLS1_RECORD_DATA_INTERNAL *)item->data;
120 		ssl3_release_buffer(&rdata->rbuf);
121 		free(item->data);
122 		pitem_free(item);
123 	}
124 }
125 
126 static void
127 dtls1_drain_fragments(pqueue queue)
128 {
129 	pitem *item;
130 
131 	if (queue == NULL)
132 		return;
133 
134 	while ((item = pqueue_pop(queue)) != NULL) {
135 		dtls1_hm_fragment_free(item->data);
136 		pitem_free(item);
137 	}
138 }
139 
140 static void
141 dtls1_clear_queues(SSL *s)
142 {
143 	dtls1_drain_records(D1I(s)->unprocessed_rcds.q);
144 	dtls1_drain_fragments(D1I(s)->buffered_messages);
145 	dtls1_drain_fragments(s->d1->sent_messages);
146 	dtls1_drain_records(D1I(s)->buffered_app_data.q);
147 }
148 
149 void
150 dtls1_free(SSL *s)
151 {
152 	if (s == NULL)
153 		return;
154 
155 	ssl3_free(s);
156 
157 	dtls1_clear_queues(s);
158 
159 	pqueue_free(D1I(s)->unprocessed_rcds.q);
160 	pqueue_free(D1I(s)->buffered_messages);
161 	pqueue_free(s->d1->sent_messages);
162 	pqueue_free(D1I(s)->buffered_app_data.q);
163 
164 	freezero(s->d1->internal, sizeof(*s->d1->internal));
165 	freezero(s->d1, sizeof(*s->d1));
166 
167 	s->d1 = NULL;
168 }
169 
170 void
171 dtls1_clear(SSL *s)
172 {
173 	struct dtls1_state_internal_st *internal;
174 	pqueue unprocessed_rcds;
175 	pqueue buffered_messages;
176 	pqueue sent_messages;
177 	pqueue buffered_app_data;
178 	unsigned int mtu;
179 
180 	if (s->d1) {
181 		unprocessed_rcds = D1I(s)->unprocessed_rcds.q;
182 		buffered_messages = D1I(s)->buffered_messages;
183 		sent_messages = s->d1->sent_messages;
184 		buffered_app_data = D1I(s)->buffered_app_data.q;
185 		mtu = D1I(s)->mtu;
186 
187 		dtls1_clear_queues(s);
188 
189 		memset(s->d1->internal, 0, sizeof(*s->d1->internal));
190 		internal = s->d1->internal;
191 		memset(s->d1, 0, sizeof(*s->d1));
192 		s->d1->internal = internal;
193 
194 		D1I(s)->unprocessed_rcds.epoch =
195 		    tls12_record_layer_read_epoch(s->internal->rl) + 1;
196 
197 		if (s->server) {
198 			D1I(s)->cookie_len = sizeof(D1I(s)->cookie);
199 		}
200 
201 		if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
202 			D1I(s)->mtu = mtu;
203 		}
204 
205 		D1I(s)->unprocessed_rcds.q = unprocessed_rcds;
206 		D1I(s)->buffered_messages = buffered_messages;
207 		s->d1->sent_messages = sent_messages;
208 		D1I(s)->buffered_app_data.q = buffered_app_data;
209 	}
210 
211 	ssl3_clear(s);
212 
213 	s->version = DTLS1_VERSION;
214 }
215 
216 long
217 dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
218 {
219 	int ret = 0;
220 
221 	switch (cmd) {
222 	case DTLS_CTRL_GET_TIMEOUT:
223 		if (dtls1_get_timeout(s, (struct timeval*) parg) != NULL) {
224 			ret = 1;
225 		}
226 		break;
227 	case DTLS_CTRL_HANDLE_TIMEOUT:
228 		ret = dtls1_handle_timeout(s);
229 		break;
230 	case DTLS_CTRL_LISTEN:
231 		ret = dtls1_listen(s, parg);
232 		break;
233 
234 	default:
235 		ret = ssl3_ctrl(s, cmd, larg, parg);
236 		break;
237 	}
238 	return (ret);
239 }
240 
241 /*
242  * As it's impossible to use stream ciphers in "datagram" mode, this
243  * simple filter is designed to disengage them in DTLS. Unfortunately
244  * there is no universal way to identify stream SSL_CIPHER, so we have
245  * to explicitly list their SSL_* codes. Currently RC4 is the only one
246  * available, but if new ones emerge, they will have to be added...
247  */
248 const SSL_CIPHER *
249 dtls1_get_cipher(unsigned int u)
250 {
251 	const SSL_CIPHER *cipher;
252 
253 	if ((cipher = ssl3_get_cipher(u)) == NULL)
254 		return NULL;
255 
256 	if (cipher->algorithm_enc == SSL_RC4)
257 		return NULL;
258 
259 	return cipher;
260 }
261 
262 void
263 dtls1_start_timer(SSL *s)
264 {
265 
266 	/* If timer is not set, initialize duration with 1 second */
267 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
268 		s->d1->timeout_duration = 1;
269 	}
270 
271 	/* Set timeout to current time */
272 	gettimeofday(&(s->d1->next_timeout), NULL);
273 
274 	/* Add duration to current time */
275 	s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
276 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
277 	    &s->d1->next_timeout);
278 }
279 
280 struct timeval*
281 dtls1_get_timeout(SSL *s, struct timeval* timeleft)
282 {
283 	struct timeval timenow;
284 
285 	/* If no timeout is set, just return NULL */
286 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
287 		return NULL;
288 	}
289 
290 	/* Get current time */
291 	gettimeofday(&timenow, NULL);
292 
293 	/* If timer already expired, set remaining time to 0 */
294 	if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
295 	    (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
296 	     s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
297 		memset(timeleft, 0, sizeof(struct timeval));
298 		return timeleft;
299 	}
300 
301 	/* Calculate time left until timer expires */
302 	memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
303 	timeleft->tv_sec -= timenow.tv_sec;
304 	timeleft->tv_usec -= timenow.tv_usec;
305 	if (timeleft->tv_usec < 0) {
306 		timeleft->tv_sec--;
307 		timeleft->tv_usec += 1000000;
308 	}
309 
310 	/* If remaining time is less than 15 ms, set it to 0
311 	 * to prevent issues because of small devergences with
312 	 * socket timeouts.
313 	 */
314 	if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
315 		memset(timeleft, 0, sizeof(struct timeval));
316 	}
317 
318 
319 	return timeleft;
320 }
321 
322 int
323 dtls1_is_timer_expired(SSL *s)
324 {
325 	struct timeval timeleft;
326 
327 	/* Get time left until timeout, return false if no timer running */
328 	if (dtls1_get_timeout(s, &timeleft) == NULL) {
329 		return 0;
330 	}
331 
332 	/* Return false if timer is not expired yet */
333 	if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
334 		return 0;
335 	}
336 
337 	/* Timer expired, so return true */
338 	return 1;
339 }
340 
341 void
342 dtls1_double_timeout(SSL *s)
343 {
344 	s->d1->timeout_duration *= 2;
345 	if (s->d1->timeout_duration > 60)
346 		s->d1->timeout_duration = 60;
347 	dtls1_start_timer(s);
348 }
349 
350 void
351 dtls1_stop_timer(SSL *s)
352 {
353 	/* Reset everything */
354 	memset(&(D1I(s)->timeout), 0, sizeof(struct dtls1_timeout_st));
355 	memset(&(s->d1->next_timeout), 0, sizeof(struct timeval));
356 	s->d1->timeout_duration = 1;
357 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
358 	    &(s->d1->next_timeout));
359 	/* Clear retransmission buffer */
360 	dtls1_clear_record_buffer(s);
361 }
362 
363 int
364 dtls1_check_timeout_num(SSL *s)
365 {
366 	D1I(s)->timeout.num_alerts++;
367 
368 	/* Reduce MTU after 2 unsuccessful retransmissions */
369 	if (D1I(s)->timeout.num_alerts > 2) {
370 		D1I(s)->mtu = BIO_ctrl(SSL_get_wbio(s),
371 		    BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
372 
373 	}
374 
375 	if (D1I(s)->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
376 		/* fail the connection, enough alerts have been sent */
377 		SSLerror(s, SSL_R_READ_TIMEOUT_EXPIRED);
378 		return -1;
379 	}
380 
381 	return 0;
382 }
383 
384 int
385 dtls1_handle_timeout(SSL *s)
386 {
387 	/* if no timer is expired, don't do anything */
388 	if (!dtls1_is_timer_expired(s)) {
389 		return 0;
390 	}
391 
392 	dtls1_double_timeout(s);
393 
394 	if (dtls1_check_timeout_num(s) < 0)
395 		return -1;
396 
397 	D1I(s)->timeout.read_timeouts++;
398 	if (D1I(s)->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
399 		D1I(s)->timeout.read_timeouts = 1;
400 	}
401 
402 	dtls1_start_timer(s);
403 	return dtls1_retransmit_buffered_messages(s);
404 }
405 
406 int
407 dtls1_listen(SSL *s, struct sockaddr *client)
408 {
409 	int ret;
410 
411 	/* Ensure there is no state left over from a previous invocation */
412 	SSL_clear(s);
413 
414 	SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
415 	D1I(s)->listen = 1;
416 
417 	ret = SSL_accept(s);
418 	if (ret <= 0)
419 		return ret;
420 
421 	(void)BIO_dgram_get_peer(SSL_get_rbio(s), client);
422 	return 1;
423 }
424