xref: /openbsd/lib/libssl/d1_lib.c (revision 09467b48) 
1 /* $OpenBSD: d1_lib.c,v 1.46 2020/07/07 19:31:11 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 "pqueue.h"
71 #include "ssl_locl.h"
72 
73 static int dtls1_listen(SSL *s, struct sockaddr *client);
74 
75 SSL3_ENC_METHOD DTLSv1_enc_data = {
76 	.enc_flags = SSL_ENC_FLAG_EXPLICIT_IV,
77 };
78 
79 int
80 dtls1_new(SSL *s)
81 {
82 	DTLS1_STATE *d1;
83 
84 	if (!ssl3_new(s))
85 		return (0);
86 	if ((d1 = calloc(1, sizeof(*d1))) == NULL) {
87 		ssl3_free(s);
88 		return (0);
89 	}
90 	if ((d1->internal = calloc(1, sizeof(*d1->internal))) == NULL) {
91 		free(d1);
92 		ssl3_free(s);
93 		return (0);
94 	}
95 
96 	/* d1->handshake_epoch=0; */
97 
98 	d1->internal->unprocessed_rcds.q = pqueue_new();
99 	d1->internal->processed_rcds.q = pqueue_new();
100 	d1->internal->buffered_messages = pqueue_new();
101 	d1->sent_messages = pqueue_new();
102 	d1->internal->buffered_app_data.q = pqueue_new();
103 
104 	if (s->server) {
105 		d1->internal->cookie_len = sizeof(D1I(s)->cookie);
106 	}
107 
108 	if (!d1->internal->unprocessed_rcds.q || !d1->internal->processed_rcds.q ||
109 	    !d1->internal->buffered_messages || !d1->sent_messages ||
110 	    !d1->internal->buffered_app_data.q) {
111 		pqueue_free(d1->internal->unprocessed_rcds.q);
112 		pqueue_free(d1->internal->processed_rcds.q);
113 		pqueue_free(d1->internal->buffered_messages);
114 		pqueue_free(d1->sent_messages);
115 		pqueue_free(d1->internal->buffered_app_data.q);
116 		free(d1);
117 		ssl3_free(s);
118 		return (0);
119 	}
120 
121 	s->d1 = d1;
122 	s->method->internal->ssl_clear(s);
123 	return (1);
124 }
125 
126 static void
127 dtls1_clear_queues(SSL *s)
128 {
129 	pitem *item = NULL;
130 	hm_fragment *frag = NULL;
131 	DTLS1_RECORD_DATA_INTERNAL *rdata;
132 
133 	while ((item = pqueue_pop(D1I(s)->unprocessed_rcds.q)) != NULL) {
134 		rdata = (DTLS1_RECORD_DATA_INTERNAL *) item->data;
135 		free(rdata->rbuf.buf);
136 		free(item->data);
137 		pitem_free(item);
138 	}
139 
140 	while ((item = pqueue_pop(D1I(s)->processed_rcds.q)) != NULL) {
141 		rdata = (DTLS1_RECORD_DATA_INTERNAL *) item->data;
142 		free(rdata->rbuf.buf);
143 		free(item->data);
144 		pitem_free(item);
145 	}
146 
147 	while ((item = pqueue_pop(D1I(s)->buffered_messages)) != NULL) {
148 		frag = (hm_fragment *)item->data;
149 		free(frag->fragment);
150 		free(frag);
151 		pitem_free(item);
152 	}
153 
154 	while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
155 		frag = (hm_fragment *)item->data;
156 		free(frag->fragment);
157 		free(frag);
158 		pitem_free(item);
159 	}
160 
161 	while ((item = pqueue_pop(D1I(s)->buffered_app_data.q)) != NULL) {
162 		rdata = (DTLS1_RECORD_DATA_INTERNAL *) item->data;
163 		free(rdata->rbuf.buf);
164 		free(item->data);
165 		pitem_free(item);
166 	}
167 }
168 
169 void
170 dtls1_free(SSL *s)
171 {
172 	if (s == NULL)
173 		return;
174 
175 	ssl3_free(s);
176 
177 	dtls1_clear_queues(s);
178 
179 	pqueue_free(D1I(s)->unprocessed_rcds.q);
180 	pqueue_free(D1I(s)->processed_rcds.q);
181 	pqueue_free(D1I(s)->buffered_messages);
182 	pqueue_free(s->d1->sent_messages);
183 	pqueue_free(D1I(s)->buffered_app_data.q);
184 
185 	freezero(s->d1->internal, sizeof(*s->d1->internal));
186 	freezero(s->d1, sizeof(*s->d1));
187 
188 	s->d1 = NULL;
189 }
190 
191 void
192 dtls1_clear(SSL *s)
193 {
194 	struct dtls1_state_internal_st *internal;
195 	pqueue unprocessed_rcds;
196 	pqueue processed_rcds;
197 	pqueue buffered_messages;
198 	pqueue sent_messages;
199 	pqueue buffered_app_data;
200 	unsigned int mtu;
201 
202 	if (s->d1) {
203 		unprocessed_rcds = D1I(s)->unprocessed_rcds.q;
204 		processed_rcds = D1I(s)->processed_rcds.q;
205 		buffered_messages = D1I(s)->buffered_messages;
206 		sent_messages = s->d1->sent_messages;
207 		buffered_app_data = D1I(s)->buffered_app_data.q;
208 		mtu = D1I(s)->mtu;
209 
210 		dtls1_clear_queues(s);
211 
212 		memset(s->d1->internal, 0, sizeof(*s->d1->internal));
213 		internal = s->d1->internal;
214 		memset(s->d1, 0, sizeof(*s->d1));
215 		s->d1->internal = internal;
216 
217 		if (s->server) {
218 			D1I(s)->cookie_len = sizeof(D1I(s)->cookie);
219 		}
220 
221 		if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
222 			D1I(s)->mtu = mtu;
223 		}
224 
225 		D1I(s)->unprocessed_rcds.q = unprocessed_rcds;
226 		D1I(s)->processed_rcds.q = processed_rcds;
227 		D1I(s)->buffered_messages = buffered_messages;
228 		s->d1->sent_messages = sent_messages;
229 		D1I(s)->buffered_app_data.q = buffered_app_data;
230 	}
231 
232 	ssl3_clear(s);
233 
234 	s->version = DTLS1_VERSION;
235 }
236 
237 long
238 dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
239 {
240 	int ret = 0;
241 
242 	switch (cmd) {
243 	case DTLS_CTRL_GET_TIMEOUT:
244 		if (dtls1_get_timeout(s, (struct timeval*) parg) != NULL) {
245 			ret = 1;
246 		}
247 		break;
248 	case DTLS_CTRL_HANDLE_TIMEOUT:
249 		ret = dtls1_handle_timeout(s);
250 		break;
251 	case DTLS_CTRL_LISTEN:
252 		ret = dtls1_listen(s, parg);
253 		break;
254 
255 	default:
256 		ret = ssl3_ctrl(s, cmd, larg, parg);
257 		break;
258 	}
259 	return (ret);
260 }
261 
262 /*
263  * As it's impossible to use stream ciphers in "datagram" mode, this
264  * simple filter is designed to disengage them in DTLS. Unfortunately
265  * there is no universal way to identify stream SSL_CIPHER, so we have
266  * to explicitly list their SSL_* codes. Currently RC4 is the only one
267  * available, but if new ones emerge, they will have to be added...
268  */
269 const SSL_CIPHER *
270 dtls1_get_cipher(unsigned int u)
271 {
272 	const SSL_CIPHER *ciph = ssl3_get_cipher(u);
273 
274 	if (ciph != NULL) {
275 		if (ciph->algorithm_enc == SSL_RC4)
276 			return NULL;
277 	}
278 
279 	return ciph;
280 }
281 
282 void
283 dtls1_start_timer(SSL *s)
284 {
285 
286 	/* If timer is not set, initialize duration with 1 second */
287 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
288 		s->d1->timeout_duration = 1;
289 	}
290 
291 	/* Set timeout to current time */
292 	gettimeofday(&(s->d1->next_timeout), NULL);
293 
294 	/* Add duration to current time */
295 	s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
296 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
297 	    &s->d1->next_timeout);
298 }
299 
300 struct timeval*
301 dtls1_get_timeout(SSL *s, struct timeval* timeleft)
302 {
303 	struct timeval timenow;
304 
305 	/* If no timeout is set, just return NULL */
306 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
307 		return NULL;
308 	}
309 
310 	/* Get current time */
311 	gettimeofday(&timenow, NULL);
312 
313 	/* If timer already expired, set remaining time to 0 */
314 	if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
315 	    (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
316 	     s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
317 		memset(timeleft, 0, sizeof(struct timeval));
318 		return timeleft;
319 	}
320 
321 	/* Calculate time left until timer expires */
322 	memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
323 	timeleft->tv_sec -= timenow.tv_sec;
324 	timeleft->tv_usec -= timenow.tv_usec;
325 	if (timeleft->tv_usec < 0) {
326 		timeleft->tv_sec--;
327 		timeleft->tv_usec += 1000000;
328 	}
329 
330 	/* If remaining time is less than 15 ms, set it to 0
331 	 * to prevent issues because of small devergences with
332 	 * socket timeouts.
333 	 */
334 	if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
335 		memset(timeleft, 0, sizeof(struct timeval));
336 	}
337 
338 
339 	return timeleft;
340 }
341 
342 int
343 dtls1_is_timer_expired(SSL *s)
344 {
345 	struct timeval timeleft;
346 
347 	/* Get time left until timeout, return false if no timer running */
348 	if (dtls1_get_timeout(s, &timeleft) == NULL) {
349 		return 0;
350 	}
351 
352 	/* Return false if timer is not expired yet */
353 	if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
354 		return 0;
355 	}
356 
357 	/* Timer expired, so return true */
358 	return 1;
359 }
360 
361 void
362 dtls1_double_timeout(SSL *s)
363 {
364 	s->d1->timeout_duration *= 2;
365 	if (s->d1->timeout_duration > 60)
366 		s->d1->timeout_duration = 60;
367 	dtls1_start_timer(s);
368 }
369 
370 void
371 dtls1_stop_timer(SSL *s)
372 {
373 	/* Reset everything */
374 	memset(&(D1I(s)->timeout), 0, sizeof(struct dtls1_timeout_st));
375 	memset(&(s->d1->next_timeout), 0, sizeof(struct timeval));
376 	s->d1->timeout_duration = 1;
377 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
378 	    &(s->d1->next_timeout));
379 	/* Clear retransmission buffer */
380 	dtls1_clear_record_buffer(s);
381 }
382 
383 int
384 dtls1_check_timeout_num(SSL *s)
385 {
386 	D1I(s)->timeout.num_alerts++;
387 
388 	/* Reduce MTU after 2 unsuccessful retransmissions */
389 	if (D1I(s)->timeout.num_alerts > 2) {
390 		D1I(s)->mtu = BIO_ctrl(SSL_get_wbio(s),
391 		    BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
392 
393 	}
394 
395 	if (D1I(s)->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
396 		/* fail the connection, enough alerts have been sent */
397 		SSLerror(s, SSL_R_READ_TIMEOUT_EXPIRED);
398 		return -1;
399 	}
400 
401 	return 0;
402 }
403 
404 int
405 dtls1_handle_timeout(SSL *s)
406 {
407 	/* if no timer is expired, don't do anything */
408 	if (!dtls1_is_timer_expired(s)) {
409 		return 0;
410 	}
411 
412 	dtls1_double_timeout(s);
413 
414 	if (dtls1_check_timeout_num(s) < 0)
415 		return -1;
416 
417 	D1I(s)->timeout.read_timeouts++;
418 	if (D1I(s)->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
419 		D1I(s)->timeout.read_timeouts = 1;
420 	}
421 
422 	dtls1_start_timer(s);
423 	return dtls1_retransmit_buffered_messages(s);
424 }
425 
426 int
427 dtls1_listen(SSL *s, struct sockaddr *client)
428 {
429 	int ret;
430 
431 	/* Ensure there is no state left over from a previous invocation */
432 	SSL_clear(s);
433 
434 	SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
435 	D1I(s)->listen = 1;
436 
437 	ret = SSL_accept(s);
438 	if (ret <= 0)
439 		return ret;
440 
441 	(void)BIO_dgram_get_peer(SSL_get_rbio(s), client);
442 	return 1;
443 }
444 
445 void
446 dtls1_build_sequence_number(unsigned char *dst, unsigned char *seq,
447     unsigned short epoch)
448 {
449 	CBB cbb;
450 
451 	if (!CBB_init_fixed(&cbb, dst, SSL3_SEQUENCE_SIZE))
452 		goto err;
453 	if (!CBB_add_u16(&cbb, epoch))
454 		goto err;
455 	if (!CBB_add_bytes(&cbb, &seq[2], SSL3_SEQUENCE_SIZE - 2))
456 		goto err;
457 	if (!CBB_finish(&cbb, NULL, NULL))
458 		goto err;
459 
460 	return;
461 
462  err:
463 	CBB_cleanup(&cbb);
464 }
465