1 /*
2 * Copyright 2005-2024 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include "internal/e_os.h"
11 #include "internal/e_winsock.h" /* struct timeval for DTLS_CTRL_GET_TIMEOUT */
12 #include <stdio.h>
13 #include <openssl/objects.h>
14 #include <openssl/rand.h>
15 #include "ssl_local.h"
16 #include "internal/time.h"
17
18 static int dtls1_handshake_write(SSL_CONNECTION *s);
19 static size_t dtls1_link_min_mtu(void);
20
21 /* XDTLS: figure out the right values */
22 static const size_t g_probable_mtu[] = { 1500, 512, 256 };
23
24 const SSL3_ENC_METHOD DTLSv1_enc_data = {
25 tls1_setup_key_block,
26 tls1_generate_master_secret,
27 tls1_change_cipher_state,
28 tls1_final_finish_mac,
29 TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
30 TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
31 tls1_alert_code,
32 tls1_export_keying_material,
33 SSL_ENC_FLAG_DTLS,
34 dtls1_set_handshake_header,
35 dtls1_close_construct_packet,
36 dtls1_handshake_write
37 };
38
39 const SSL3_ENC_METHOD DTLSv1_2_enc_data = {
40 tls1_setup_key_block,
41 tls1_generate_master_secret,
42 tls1_change_cipher_state,
43 tls1_final_finish_mac,
44 TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
45 TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
46 tls1_alert_code,
47 tls1_export_keying_material,
48 SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_SIGALGS
49 | SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS,
50 dtls1_set_handshake_header,
51 dtls1_close_construct_packet,
52 dtls1_handshake_write
53 };
54
dtls1_default_timeout(void)55 OSSL_TIME dtls1_default_timeout(void)
56 {
57 /*
58 * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
59 * http, the cache would over fill
60 */
61 return ossl_seconds2time(60 * 60 * 2);
62 }
63
dtls1_new(SSL * ssl)64 int dtls1_new(SSL *ssl)
65 {
66 DTLS1_STATE *d1;
67 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
68
69 if (s == NULL)
70 return 0;
71
72 if (!DTLS_RECORD_LAYER_new(&s->rlayer)) {
73 return 0;
74 }
75
76 if (!ssl3_new(ssl))
77 return 0;
78 if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) {
79 ssl3_free(ssl);
80 return 0;
81 }
82
83 d1->buffered_messages = pqueue_new();
84 d1->sent_messages = pqueue_new();
85
86 if (s->server) {
87 d1->cookie_len = sizeof(s->d1->cookie);
88 }
89
90 d1->link_mtu = 0;
91 d1->mtu = 0;
92
93 if (d1->buffered_messages == NULL || d1->sent_messages == NULL) {
94 pqueue_free(d1->buffered_messages);
95 pqueue_free(d1->sent_messages);
96 OPENSSL_free(d1);
97 ssl3_free(ssl);
98 return 0;
99 }
100
101 s->d1 = d1;
102
103 if (!ssl->method->ssl_clear(ssl))
104 return 0;
105
106 return 1;
107 }
108
dtls1_clear_queues(SSL_CONNECTION * s)109 static void dtls1_clear_queues(SSL_CONNECTION *s)
110 {
111 dtls1_clear_received_buffer(s);
112 dtls1_clear_sent_buffer(s);
113 }
114
dtls1_clear_received_buffer(SSL_CONNECTION * s)115 void dtls1_clear_received_buffer(SSL_CONNECTION *s)
116 {
117 pitem *item = NULL;
118 hm_fragment *frag = NULL;
119
120 while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
121 frag = (hm_fragment *)item->data;
122 dtls1_hm_fragment_free(frag);
123 pitem_free(item);
124 }
125 }
126
dtls1_clear_sent_buffer(SSL_CONNECTION * s)127 void dtls1_clear_sent_buffer(SSL_CONNECTION *s)
128 {
129 pitem *item = NULL;
130 hm_fragment *frag = NULL;
131
132 while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
133 frag = (hm_fragment *)item->data;
134
135 if (frag->msg_header.is_ccs
136 && frag->msg_header.saved_retransmit_state.wrlmethod != NULL
137 && s->rlayer.wrl != frag->msg_header.saved_retransmit_state.wrl) {
138 /*
139 * If we're freeing the CCS then we're done with the old wrl and it
140 * can bee freed
141 */
142 frag->msg_header.saved_retransmit_state.wrlmethod->free(frag->msg_header.saved_retransmit_state.wrl);
143 }
144
145 dtls1_hm_fragment_free(frag);
146 pitem_free(item);
147 }
148 }
149
150
dtls1_free(SSL * ssl)151 void dtls1_free(SSL *ssl)
152 {
153 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
154
155 if (s == NULL)
156 return;
157
158 if (s->d1 != NULL) {
159 dtls1_clear_queues(s);
160 pqueue_free(s->d1->buffered_messages);
161 pqueue_free(s->d1->sent_messages);
162 }
163
164 DTLS_RECORD_LAYER_free(&s->rlayer);
165
166 ssl3_free(ssl);
167
168 OPENSSL_free(s->d1);
169 s->d1 = NULL;
170 }
171
dtls1_clear(SSL * ssl)172 int dtls1_clear(SSL *ssl)
173 {
174 pqueue *buffered_messages;
175 pqueue *sent_messages;
176 size_t mtu;
177 size_t link_mtu;
178
179 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
180
181 if (s == NULL)
182 return 0;
183
184 DTLS_RECORD_LAYER_clear(&s->rlayer);
185
186 if (s->d1) {
187 DTLS_timer_cb timer_cb = s->d1->timer_cb;
188
189 buffered_messages = s->d1->buffered_messages;
190 sent_messages = s->d1->sent_messages;
191 mtu = s->d1->mtu;
192 link_mtu = s->d1->link_mtu;
193
194 dtls1_clear_queues(s);
195
196 memset(s->d1, 0, sizeof(*s->d1));
197
198 /* Restore the timer callback from previous state */
199 s->d1->timer_cb = timer_cb;
200
201 if (s->server) {
202 s->d1->cookie_len = sizeof(s->d1->cookie);
203 }
204
205 if (SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU) {
206 s->d1->mtu = mtu;
207 s->d1->link_mtu = link_mtu;
208 }
209
210 s->d1->buffered_messages = buffered_messages;
211 s->d1->sent_messages = sent_messages;
212 }
213
214 if (!ssl3_clear(ssl))
215 return 0;
216
217 if (ssl->method->version == DTLS_ANY_VERSION)
218 s->version = DTLS_MAX_VERSION_INTERNAL;
219 #ifndef OPENSSL_NO_DTLS1_METHOD
220 else if (s->options & SSL_OP_CISCO_ANYCONNECT)
221 s->client_version = s->version = DTLS1_BAD_VER;
222 #endif
223 else
224 s->version = ssl->method->version;
225
226 return 1;
227 }
228
dtls1_ctrl(SSL * ssl,int cmd,long larg,void * parg)229 long dtls1_ctrl(SSL *ssl, int cmd, long larg, void *parg)
230 {
231 int ret = 0;
232 OSSL_TIME t;
233 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
234
235 if (s == NULL)
236 return 0;
237
238 switch (cmd) {
239 case DTLS_CTRL_GET_TIMEOUT:
240 if (dtls1_get_timeout(s, &t)) {
241 *(struct timeval *)parg = ossl_time_to_timeval(t);
242 ret = 1;
243 }
244 break;
245 case DTLS_CTRL_HANDLE_TIMEOUT:
246 ret = dtls1_handle_timeout(s);
247 break;
248 case DTLS_CTRL_SET_LINK_MTU:
249 if (larg < (long)dtls1_link_min_mtu())
250 return 0;
251 s->d1->link_mtu = larg;
252 return 1;
253 case DTLS_CTRL_GET_LINK_MIN_MTU:
254 return (long)dtls1_link_min_mtu();
255 case SSL_CTRL_SET_MTU:
256 /*
257 * We may not have a BIO set yet so can't call dtls1_min_mtu()
258 * We'll have to make do with dtls1_link_min_mtu() and max overhead
259 */
260 if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
261 return 0;
262 s->d1->mtu = larg;
263 return larg;
264 default:
265 ret = ssl3_ctrl(ssl, cmd, larg, parg);
266 break;
267 }
268 return ret;
269 }
270
dtls1_bio_set_next_timeout(BIO * bio,const DTLS1_STATE * d1)271 static void dtls1_bio_set_next_timeout(BIO *bio, const DTLS1_STATE *d1)
272 {
273 struct timeval tv = ossl_time_to_timeval(d1->next_timeout);
274
275 BIO_ctrl(bio, BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, &tv);
276 }
277
dtls1_start_timer(SSL_CONNECTION * s)278 void dtls1_start_timer(SSL_CONNECTION *s)
279 {
280 OSSL_TIME duration;
281 SSL *ssl = SSL_CONNECTION_GET_SSL(s);
282
283 #ifndef OPENSSL_NO_SCTP
284 /* Disable timer for SCTP */
285 if (BIO_dgram_is_sctp(SSL_get_wbio(ssl))) {
286 s->d1->next_timeout = ossl_time_zero();
287 return;
288 }
289 #endif
290
291 /*
292 * If timer is not set, initialize duration with 1 second or
293 * a user-specified value if the timer callback is installed.
294 */
295 if (ossl_time_is_zero(s->d1->next_timeout)) {
296 if (s->d1->timer_cb != NULL)
297 s->d1->timeout_duration_us = s->d1->timer_cb(ssl, 0);
298 else
299 s->d1->timeout_duration_us = 1000000;
300 }
301
302 /* Set timeout to current time plus duration */
303 duration = ossl_us2time(s->d1->timeout_duration_us);
304 s->d1->next_timeout = ossl_time_add(ossl_time_now(), duration);
305
306 /* set s->d1->next_timeout into ssl->rbio interface */
307 dtls1_bio_set_next_timeout(SSL_get_rbio(ssl), s->d1);
308 }
309
dtls1_get_timeout(const SSL_CONNECTION * s,OSSL_TIME * timeleft)310 int dtls1_get_timeout(const SSL_CONNECTION *s, OSSL_TIME *timeleft)
311 {
312 OSSL_TIME timenow;
313
314 /* If no timeout is set, just return NULL */
315 if (ossl_time_is_zero(s->d1->next_timeout))
316 return 0;
317
318 /* Get current time */
319 timenow = ossl_time_now();
320
321 /*
322 * If timer already expired or if remaining time is less than 15 ms,
323 * set it to 0 to prevent issues because of small divergences with
324 * socket timeouts.
325 */
326 *timeleft = ossl_time_subtract(s->d1->next_timeout, timenow);
327 if (ossl_time_compare(*timeleft, ossl_ms2time(15)) <= 0)
328 *timeleft = ossl_time_zero();
329 return 1;
330 }
331
dtls1_is_timer_expired(SSL_CONNECTION * s)332 int dtls1_is_timer_expired(SSL_CONNECTION *s)
333 {
334 OSSL_TIME timeleft;
335
336 /* Get time left until timeout, return false if no timer running */
337 if (!dtls1_get_timeout(s, &timeleft))
338 return 0;
339
340 /* Return false if timer is not expired yet */
341 if (!ossl_time_is_zero(timeleft))
342 return 0;
343
344 /* Timer expired, so return true */
345 return 1;
346 }
347
dtls1_double_timeout(SSL_CONNECTION * s)348 static void dtls1_double_timeout(SSL_CONNECTION *s)
349 {
350 s->d1->timeout_duration_us *= 2;
351 if (s->d1->timeout_duration_us > 60000000)
352 s->d1->timeout_duration_us = 60000000;
353 }
354
dtls1_stop_timer(SSL_CONNECTION * s)355 void dtls1_stop_timer(SSL_CONNECTION *s)
356 {
357 /* Reset everything */
358 s->d1->timeout_num_alerts = 0;
359 s->d1->next_timeout = ossl_time_zero();
360 s->d1->timeout_duration_us = 1000000;
361 dtls1_bio_set_next_timeout(s->rbio, s->d1);
362 /* Clear retransmission buffer */
363 dtls1_clear_sent_buffer(s);
364 }
365
dtls1_check_timeout_num(SSL_CONNECTION * s)366 int dtls1_check_timeout_num(SSL_CONNECTION *s)
367 {
368 size_t mtu;
369 SSL *ssl = SSL_CONNECTION_GET_SSL(s);
370
371 s->d1->timeout_num_alerts++;
372
373 /* Reduce MTU after 2 unsuccessful retransmissions */
374 if (s->d1->timeout_num_alerts > 2
375 && !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
376 mtu =
377 BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
378 if (mtu < s->d1->mtu)
379 s->d1->mtu = mtu;
380 }
381
382 if (s->d1->timeout_num_alerts > DTLS1_TMO_ALERT_COUNT) {
383 /* fail the connection, enough alerts have been sent */
384 SSLfatal(s, SSL_AD_NO_ALERT, SSL_R_READ_TIMEOUT_EXPIRED);
385 return -1;
386 }
387
388 return 0;
389 }
390
dtls1_handle_timeout(SSL_CONNECTION * s)391 int dtls1_handle_timeout(SSL_CONNECTION *s)
392 {
393 /* if no timer is expired, don't do anything */
394 if (!dtls1_is_timer_expired(s)) {
395 return 0;
396 }
397
398 if (s->d1->timer_cb != NULL)
399 s->d1->timeout_duration_us = s->d1->timer_cb(SSL_CONNECTION_GET_SSL(s),
400 s->d1->timeout_duration_us);
401 else
402 dtls1_double_timeout(s);
403
404 if (dtls1_check_timeout_num(s) < 0) {
405 /* SSLfatal() already called */
406 return -1;
407 }
408
409 dtls1_start_timer(s);
410 /* Calls SSLfatal() if required */
411 return dtls1_retransmit_buffered_messages(s);
412 }
413
414 #define LISTEN_SUCCESS 2
415 #define LISTEN_SEND_VERIFY_REQUEST 1
416
417 #ifndef OPENSSL_NO_SOCK
DTLSv1_listen(SSL * ssl,BIO_ADDR * client)418 int DTLSv1_listen(SSL *ssl, BIO_ADDR *client)
419 {
420 int next, n, ret = 0;
421 unsigned char cookie[DTLS1_COOKIE_LENGTH];
422 unsigned char seq[SEQ_NUM_SIZE];
423 const unsigned char *data;
424 unsigned char *buf = NULL, *wbuf;
425 size_t fragoff, fraglen, msglen;
426 unsigned int rectype, versmajor, versminor, msgseq, msgtype, clientvers, cookielen;
427 BIO *rbio, *wbio;
428 BIO_ADDR *tmpclient = NULL;
429 PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
430 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
431
432 if (s == NULL)
433 return -1;
434
435 if (s->handshake_func == NULL) {
436 /* Not properly initialized yet */
437 SSL_set_accept_state(ssl);
438 }
439
440 /* Ensure there is no state left over from a previous invocation */
441 if (!SSL_clear(ssl))
442 return -1;
443
444 ERR_clear_error();
445
446 rbio = SSL_get_rbio(ssl);
447 wbio = SSL_get_wbio(ssl);
448
449 if (!rbio || !wbio) {
450 ERR_raise(ERR_LIB_SSL, SSL_R_BIO_NOT_SET);
451 return -1;
452 }
453
454 /*
455 * Note: This check deliberately excludes DTLS1_BAD_VER because that version
456 * requires the MAC to be calculated *including* the first ClientHello
457 * (without the cookie). Since DTLSv1_listen is stateless that cannot be
458 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
459 * SSL_accept)
460 */
461 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
462 ERR_raise(ERR_LIB_SSL, SSL_R_UNSUPPORTED_SSL_VERSION);
463 return -1;
464 }
465
466 buf = OPENSSL_malloc(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_PLAIN_LENGTH);
467 if (buf == NULL)
468 return -1;
469 wbuf = OPENSSL_malloc(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_PLAIN_LENGTH);
470 if (wbuf == NULL) {
471 OPENSSL_free(buf);
472 return -1;
473 }
474
475 do {
476 /* Get a packet */
477
478 clear_sys_error();
479 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH
480 + DTLS1_RT_HEADER_LENGTH);
481 if (n <= 0) {
482 if (BIO_should_retry(rbio)) {
483 /* Non-blocking IO */
484 goto end;
485 }
486 ret = -1;
487 goto end;
488 }
489
490 if (!PACKET_buf_init(&pkt, buf, n)) {
491 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
492 ret = -1;
493 goto end;
494 }
495
496 /*
497 * Parse the received record. If there are any problems with it we just
498 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
499 * resilient in the face of invalid records (e.g., invalid formatting,
500 * length, MAC, etc.). In general, invalid records SHOULD be silently
501 * discarded, thus preserving the association; however, an error MAY be
502 * logged for diagnostic purposes."
503 */
504
505 /* this packet contained a partial record, dump it */
506 if (n < DTLS1_RT_HEADER_LENGTH) {
507 ERR_raise(ERR_LIB_SSL, SSL_R_RECORD_TOO_SMALL);
508 goto end;
509 }
510
511 /* Get the record header */
512 if (!PACKET_get_1(&pkt, &rectype)
513 || !PACKET_get_1(&pkt, &versmajor)
514 || !PACKET_get_1(&pkt, &versminor)) {
515 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
516 goto end;
517 }
518
519 if (s->msg_callback)
520 s->msg_callback(0, (versmajor << 8) | versminor, SSL3_RT_HEADER, buf,
521 DTLS1_RT_HEADER_LENGTH, ssl, s->msg_callback_arg);
522
523 if (rectype != SSL3_RT_HANDSHAKE) {
524 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
525 goto end;
526 }
527
528 /*
529 * Check record version number. We only check that the major version is
530 * the same.
531 */
532 if (versmajor != DTLS1_VERSION_MAJOR) {
533 ERR_raise(ERR_LIB_SSL, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
534 goto end;
535 }
536
537 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */
538 if (!PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
539 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
540 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
541 goto end;
542 }
543 /*
544 * We allow data remaining at the end of the packet because there could
545 * be a second record (but we ignore it)
546 */
547
548 /* This is an initial ClientHello so the epoch has to be 0 */
549 if (seq[0] != 0 || seq[1] != 0) {
550 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
551 goto end;
552 }
553
554 /* Get a pointer to the raw message for the later callback */
555 data = PACKET_data(&msgpkt);
556
557 /* Finished processing the record header, now process the message */
558 if (!PACKET_get_1(&msgpkt, &msgtype)
559 || !PACKET_get_net_3_len(&msgpkt, &msglen)
560 || !PACKET_get_net_2(&msgpkt, &msgseq)
561 || !PACKET_get_net_3_len(&msgpkt, &fragoff)
562 || !PACKET_get_net_3_len(&msgpkt, &fraglen)
563 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
564 || PACKET_remaining(&msgpkt) != 0) {
565 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
566 goto end;
567 }
568
569 if (msgtype != SSL3_MT_CLIENT_HELLO) {
570 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
571 goto end;
572 }
573
574 /* Message sequence number can only be 0 or 1 */
575 if (msgseq > 2) {
576 ERR_raise(ERR_LIB_SSL, SSL_R_INVALID_SEQUENCE_NUMBER);
577 goto end;
578 }
579
580 /*
581 * We don't support fragment reassembly for ClientHellos whilst
582 * listening because that would require server side state (which is
583 * against the whole point of the ClientHello/HelloVerifyRequest
584 * mechanism). Instead we only look at the first ClientHello fragment
585 * and require that the cookie must be contained within it.
586 */
587 if (fragoff != 0 || fraglen > msglen) {
588 /* Non initial ClientHello fragment (or bad fragment) */
589 ERR_raise(ERR_LIB_SSL, SSL_R_FRAGMENTED_CLIENT_HELLO);
590 goto end;
591 }
592
593 if (s->msg_callback)
594 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
595 fraglen + DTLS1_HM_HEADER_LENGTH, ssl,
596 s->msg_callback_arg);
597
598 if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
599 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
600 goto end;
601 }
602
603 /*
604 * Verify client version is supported
605 */
606 if (DTLS_VERSION_LT(clientvers, (unsigned int)ssl->method->version) &&
607 ssl->method->version != DTLS_ANY_VERSION) {
608 ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_VERSION_NUMBER);
609 goto end;
610 }
611
612 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
613 || !PACKET_get_length_prefixed_1(&msgpayload, &session)
614 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
615 /*
616 * Could be malformed or the cookie does not fit within the initial
617 * ClientHello fragment. Either way we can't handle it.
618 */
619 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
620 goto end;
621 }
622
623 /*
624 * Check if we have a cookie or not. If not we need to send a
625 * HelloVerifyRequest.
626 */
627 if (PACKET_remaining(&cookiepkt) == 0) {
628 next = LISTEN_SEND_VERIFY_REQUEST;
629 } else {
630 /*
631 * We have a cookie, so lets check it.
632 */
633 if (ssl->ctx->app_verify_cookie_cb == NULL) {
634 ERR_raise(ERR_LIB_SSL, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
635 /* This is fatal */
636 ret = -1;
637 goto end;
638 }
639 if (ssl->ctx->app_verify_cookie_cb(ssl, PACKET_data(&cookiepkt),
640 (unsigned int)PACKET_remaining(&cookiepkt)) == 0) {
641 /*
642 * We treat invalid cookies in the same was as no cookie as
643 * per RFC6347
644 */
645 next = LISTEN_SEND_VERIFY_REQUEST;
646 } else {
647 /* Cookie verification succeeded */
648 next = LISTEN_SUCCESS;
649 }
650 }
651
652 if (next == LISTEN_SEND_VERIFY_REQUEST) {
653 WPACKET wpkt;
654 unsigned int version;
655 size_t wreclen;
656
657 /*
658 * There was no cookie in the ClientHello so we need to send a
659 * HelloVerifyRequest. If this fails we do not worry about trying
660 * to resend, we just drop it.
661 */
662
663 /* Generate the cookie */
664 if (ssl->ctx->app_gen_cookie_cb == NULL ||
665 ssl->ctx->app_gen_cookie_cb(ssl, cookie, &cookielen) == 0 ||
666 cookielen > 255) {
667 ERR_raise(ERR_LIB_SSL, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
668 /* This is fatal */
669 ret = -1;
670 goto end;
671 }
672
673 /*
674 * Special case: for hello verify request, client version 1.0 and we
675 * haven't decided which version to use yet send back using version
676 * 1.0 header: otherwise some clients will ignore it.
677 */
678 version = (ssl->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
679 : s->version;
680
681 /* Construct the record and message headers */
682 if (!WPACKET_init_static_len(&wpkt,
683 wbuf,
684 ssl_get_max_send_fragment(s)
685 + DTLS1_RT_HEADER_LENGTH,
686 0)
687 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
688 || !WPACKET_put_bytes_u16(&wpkt, version)
689 /*
690 * Record sequence number is always the same as in the
691 * received ClientHello
692 */
693 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
694 /* End of record, start sub packet for message */
695 || !WPACKET_start_sub_packet_u16(&wpkt)
696 /* Message type */
697 || !WPACKET_put_bytes_u8(&wpkt,
698 DTLS1_MT_HELLO_VERIFY_REQUEST)
699 /*
700 * Message length - doesn't follow normal TLS convention:
701 * the length isn't the last thing in the message header.
702 * We'll need to fill this in later when we know the
703 * length. Set it to zero for now
704 */
705 || !WPACKET_put_bytes_u24(&wpkt, 0)
706 /*
707 * Message sequence number is always 0 for a
708 * HelloVerifyRequest
709 */
710 || !WPACKET_put_bytes_u16(&wpkt, 0)
711 /*
712 * We never fragment a HelloVerifyRequest, so fragment
713 * offset is 0
714 */
715 || !WPACKET_put_bytes_u24(&wpkt, 0)
716 /*
717 * Fragment length is the same as message length, but
718 * this *is* the last thing in the message header so we
719 * can just start a sub-packet. No need to come back
720 * later for this one.
721 */
722 || !WPACKET_start_sub_packet_u24(&wpkt)
723 /* Create the actual HelloVerifyRequest body */
724 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
725 /* Close message body */
726 || !WPACKET_close(&wpkt)
727 /* Close record body */
728 || !WPACKET_close(&wpkt)
729 || !WPACKET_get_total_written(&wpkt, &wreclen)
730 || !WPACKET_finish(&wpkt)) {
731 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
732 WPACKET_cleanup(&wpkt);
733 /* This is fatal */
734 ret = -1;
735 goto end;
736 }
737
738 /*
739 * Fix up the message len in the message header. Its the same as the
740 * fragment len which has been filled in by WPACKET, so just copy
741 * that. Destination for the message len is after the record header
742 * plus one byte for the message content type. The source is the
743 * last 3 bytes of the message header
744 */
745 memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1],
746 &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
747 3);
748
749 if (s->msg_callback)
750 s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
751 DTLS1_RT_HEADER_LENGTH, ssl,
752 s->msg_callback_arg);
753
754 if ((tmpclient = BIO_ADDR_new()) == NULL) {
755 ERR_raise(ERR_LIB_SSL, ERR_R_BIO_LIB);
756 goto end;
757 }
758
759 /*
760 * This is unnecessary if rbio and wbio are one and the same - but
761 * maybe they're not. We ignore errors here - some BIOs do not
762 * support this.
763 */
764 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
765 (void)BIO_dgram_set_peer(wbio, tmpclient);
766 }
767 BIO_ADDR_free(tmpclient);
768 tmpclient = NULL;
769
770 if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) {
771 if (BIO_should_retry(wbio)) {
772 /*
773 * Non-blocking IO...but we're stateless, so we're just
774 * going to drop this packet.
775 */
776 goto end;
777 }
778 ret = -1;
779 goto end;
780 }
781
782 if (BIO_flush(wbio) <= 0) {
783 if (BIO_should_retry(wbio)) {
784 /*
785 * Non-blocking IO...but we're stateless, so we're just
786 * going to drop this packet.
787 */
788 goto end;
789 }
790 ret = -1;
791 goto end;
792 }
793 }
794 } while (next != LISTEN_SUCCESS);
795
796 /*
797 * Set expected sequence numbers to continue the handshake.
798 */
799 s->d1->handshake_read_seq = 1;
800 s->d1->handshake_write_seq = 1;
801 s->d1->next_handshake_write_seq = 1;
802 s->rlayer.wrlmethod->increment_sequence_ctr(s->rlayer.wrl);
803
804 /*
805 * We are doing cookie exchange, so make sure we set that option in the
806 * SSL object
807 */
808 SSL_set_options(ssl, SSL_OP_COOKIE_EXCHANGE);
809
810 /*
811 * Tell the state machine that we've done the initial hello verify
812 * exchange
813 */
814 ossl_statem_set_hello_verify_done(s);
815
816 /*
817 * Some BIOs may not support this. If we fail we clear the client address
818 */
819 if (BIO_dgram_get_peer(rbio, client) <= 0)
820 BIO_ADDR_clear(client);
821
822 /* Buffer the record for use by the record layer */
823 if (BIO_write(s->rlayer.rrlnext, buf, n) != n) {
824 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
825 ret = -1;
826 goto end;
827 }
828
829 /*
830 * Reset the record layer - but this time we can use the record we just
831 * buffered in s->rlayer.rrlnext
832 */
833 if (!ssl_set_new_record_layer(s,
834 DTLS_ANY_VERSION,
835 OSSL_RECORD_DIRECTION_READ,
836 OSSL_RECORD_PROTECTION_LEVEL_NONE, NULL, 0,
837 NULL, 0, NULL, 0, NULL, 0, NULL, 0,
838 NID_undef, NULL, NULL, NULL)) {
839 /* SSLfatal already called */
840 ret = -1;
841 goto end;
842 }
843
844 ret = 1;
845 end:
846 BIO_ADDR_free(tmpclient);
847 OPENSSL_free(buf);
848 OPENSSL_free(wbuf);
849 return ret;
850 }
851 #endif
852
dtls1_handshake_write(SSL_CONNECTION * s)853 static int dtls1_handshake_write(SSL_CONNECTION *s)
854 {
855 return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
856 }
857
dtls1_shutdown(SSL * s)858 int dtls1_shutdown(SSL *s)
859 {
860 int ret;
861 #ifndef OPENSSL_NO_SCTP
862 BIO *wbio;
863 SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL_ONLY(s);
864
865 if (s == NULL)
866 return -1;
867
868 wbio = SSL_get_wbio(s);
869 if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
870 !(sc->shutdown & SSL_SENT_SHUTDOWN)) {
871 ret = BIO_dgram_sctp_wait_for_dry(wbio);
872 if (ret < 0)
873 return -1;
874
875 if (ret == 0)
876 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
877 NULL);
878 }
879 #endif
880 ret = ssl3_shutdown(s);
881 #ifndef OPENSSL_NO_SCTP
882 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
883 #endif
884 return ret;
885 }
886
dtls1_query_mtu(SSL_CONNECTION * s)887 int dtls1_query_mtu(SSL_CONNECTION *s)
888 {
889 SSL *ssl = SSL_CONNECTION_GET_SSL(s);
890
891 if (s->d1->link_mtu) {
892 s->d1->mtu =
893 s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(ssl));
894 s->d1->link_mtu = 0;
895 }
896
897 /* AHA! Figure out the MTU, and stick to the right size */
898 if (s->d1->mtu < dtls1_min_mtu(s)) {
899 if (!(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
900 s->d1->mtu =
901 BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
902
903 /*
904 * I've seen the kernel return bogus numbers when it doesn't know
905 * (initial write), so just make sure we have a reasonable number
906 */
907 if (s->d1->mtu < dtls1_min_mtu(s)) {
908 /* Set to min mtu */
909 s->d1->mtu = dtls1_min_mtu(s);
910 BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_SET_MTU,
911 (long)s->d1->mtu, NULL);
912 }
913 } else
914 return 0;
915 }
916 return 1;
917 }
918
dtls1_link_min_mtu(void)919 static size_t dtls1_link_min_mtu(void)
920 {
921 return (g_probable_mtu[(sizeof(g_probable_mtu) /
922 sizeof(g_probable_mtu[0])) - 1]);
923 }
924
dtls1_min_mtu(SSL_CONNECTION * s)925 size_t dtls1_min_mtu(SSL_CONNECTION *s)
926 {
927 SSL *ssl = SSL_CONNECTION_GET_SSL(s);
928
929 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(ssl));
930 }
931
DTLS_get_data_mtu(const SSL * ssl)932 size_t DTLS_get_data_mtu(const SSL *ssl)
933 {
934 size_t mac_overhead, int_overhead, blocksize, ext_overhead;
935 const SSL_CIPHER *ciph = SSL_get_current_cipher(ssl);
936 size_t mtu;
937 const SSL_CONNECTION *s = SSL_CONNECTION_FROM_CONST_SSL_ONLY(ssl);
938
939 if (s == NULL)
940 return 0;
941
942 mtu = s->d1->mtu;
943
944 if (ciph == NULL)
945 return 0;
946
947 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
948 &blocksize, &ext_overhead))
949 return 0;
950
951 if (SSL_READ_ETM(s))
952 ext_overhead += mac_overhead;
953 else
954 int_overhead += mac_overhead;
955
956 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */
957 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
958 return 0;
959 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
960
961 /* Round encrypted payload down to cipher block size (for CBC etc.)
962 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
963 if (blocksize)
964 mtu -= (mtu % blocksize);
965
966 /* Subtract internal overhead (e.g. CBC padding len byte) */
967 if (int_overhead >= mtu)
968 return 0;
969 mtu -= int_overhead;
970
971 return mtu;
972 }
973
DTLS_set_timer_cb(SSL * ssl,DTLS_timer_cb cb)974 void DTLS_set_timer_cb(SSL *ssl, DTLS_timer_cb cb)
975 {
976 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl);
977
978 if (s == NULL)
979 return;
980
981 s->d1->timer_cb = cb;
982 }
983
