1 /*
2 * Copyright 2005-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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 "e_os.h"
11 #include <stdio.h>
12 #include <openssl/objects.h>
13 #include <openssl/rand.h>
14 #include "ssl_local.h"
15
16 static void get_current_time(struct timeval *t);
17 static int dtls1_handshake_write(SSL *s);
18 static size_t dtls1_link_min_mtu(void);
19
20 /* XDTLS: figure out the right values */
21 static const size_t g_probable_mtu[] = { 1500, 512, 256 };
22
23 const SSL3_ENC_METHOD DTLSv1_enc_data = {
24 tls1_enc,
25 tls1_mac,
26 tls1_setup_key_block,
27 tls1_generate_master_secret,
28 tls1_change_cipher_state,
29 tls1_final_finish_mac,
30 TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
31 TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
32 tls1_alert_code,
33 tls1_export_keying_material,
34 SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV,
35 dtls1_set_handshake_header,
36 dtls1_close_construct_packet,
37 dtls1_handshake_write
38 };
39
40 const SSL3_ENC_METHOD DTLSv1_2_enc_data = {
41 tls1_enc,
42 tls1_mac,
43 tls1_setup_key_block,
44 tls1_generate_master_secret,
45 tls1_change_cipher_state,
46 tls1_final_finish_mac,
47 TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
48 TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
49 tls1_alert_code,
50 tls1_export_keying_material,
51 SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS
52 | SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS,
53 dtls1_set_handshake_header,
54 dtls1_close_construct_packet,
55 dtls1_handshake_write
56 };
57
dtls1_default_timeout(void)58 long dtls1_default_timeout(void)
59 {
60 /*
61 * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
62 * http, the cache would over fill
63 */
64 return (60 * 60 * 2);
65 }
66
dtls1_new(SSL * s)67 int dtls1_new(SSL *s)
68 {
69 DTLS1_STATE *d1;
70
71 if (!DTLS_RECORD_LAYER_new(&s->rlayer)) {
72 return 0;
73 }
74
75 if (!ssl3_new(s))
76 return 0;
77 if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) {
78 ssl3_free(s);
79 return 0;
80 }
81
82 d1->buffered_messages = pqueue_new();
83 d1->sent_messages = pqueue_new();
84
85 if (s->server) {
86 d1->cookie_len = sizeof(s->d1->cookie);
87 }
88
89 d1->link_mtu = 0;
90 d1->mtu = 0;
91
92 if (d1->buffered_messages == NULL || d1->sent_messages == NULL) {
93 pqueue_free(d1->buffered_messages);
94 pqueue_free(d1->sent_messages);
95 OPENSSL_free(d1);
96 ssl3_free(s);
97 return 0;
98 }
99
100 s->d1 = d1;
101
102 if (!s->method->ssl_clear(s))
103 return 0;
104
105 return 1;
106 }
107
dtls1_clear_queues(SSL * s)108 static void dtls1_clear_queues(SSL *s)
109 {
110 dtls1_clear_received_buffer(s);
111 dtls1_clear_sent_buffer(s);
112 }
113
dtls1_clear_received_buffer(SSL * s)114 void dtls1_clear_received_buffer(SSL *s)
115 {
116 pitem *item = NULL;
117 hm_fragment *frag = NULL;
118
119 while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
120 frag = (hm_fragment *)item->data;
121 dtls1_hm_fragment_free(frag);
122 pitem_free(item);
123 }
124 }
125
dtls1_clear_sent_buffer(SSL * s)126 void dtls1_clear_sent_buffer(SSL *s)
127 {
128 pitem *item = NULL;
129 hm_fragment *frag = NULL;
130
131 while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
132 frag = (hm_fragment *)item->data;
133 dtls1_hm_fragment_free(frag);
134 pitem_free(item);
135 }
136 }
137
138
dtls1_free(SSL * s)139 void dtls1_free(SSL *s)
140 {
141 DTLS_RECORD_LAYER_free(&s->rlayer);
142
143 ssl3_free(s);
144
145 if (s->d1 != NULL) {
146 dtls1_clear_queues(s);
147 pqueue_free(s->d1->buffered_messages);
148 pqueue_free(s->d1->sent_messages);
149 }
150
151 OPENSSL_free(s->d1);
152 s->d1 = NULL;
153 }
154
dtls1_clear(SSL * s)155 int dtls1_clear(SSL *s)
156 {
157 pqueue *buffered_messages;
158 pqueue *sent_messages;
159 size_t mtu;
160 size_t link_mtu;
161
162 DTLS_RECORD_LAYER_clear(&s->rlayer);
163
164 if (s->d1) {
165 DTLS_timer_cb timer_cb = s->d1->timer_cb;
166
167 buffered_messages = s->d1->buffered_messages;
168 sent_messages = s->d1->sent_messages;
169 mtu = s->d1->mtu;
170 link_mtu = s->d1->link_mtu;
171
172 dtls1_clear_queues(s);
173
174 memset(s->d1, 0, sizeof(*s->d1));
175
176 /* Restore the timer callback from previous state */
177 s->d1->timer_cb = timer_cb;
178
179 if (s->server) {
180 s->d1->cookie_len = sizeof(s->d1->cookie);
181 }
182
183 if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
184 s->d1->mtu = mtu;
185 s->d1->link_mtu = link_mtu;
186 }
187
188 s->d1->buffered_messages = buffered_messages;
189 s->d1->sent_messages = sent_messages;
190 }
191
192 if (!ssl3_clear(s))
193 return 0;
194
195 if (s->method->version == DTLS_ANY_VERSION)
196 s->version = DTLS_MAX_VERSION;
197 #ifndef OPENSSL_NO_DTLS1_METHOD
198 else if (s->options & SSL_OP_CISCO_ANYCONNECT)
199 s->client_version = s->version = DTLS1_BAD_VER;
200 #endif
201 else
202 s->version = s->method->version;
203
204 return 1;
205 }
206
dtls1_ctrl(SSL * s,int cmd,long larg,void * parg)207 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
208 {
209 int ret = 0;
210
211 switch (cmd) {
212 case DTLS_CTRL_GET_TIMEOUT:
213 if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
214 ret = 1;
215 }
216 break;
217 case DTLS_CTRL_HANDLE_TIMEOUT:
218 ret = dtls1_handle_timeout(s);
219 break;
220 case DTLS_CTRL_SET_LINK_MTU:
221 if (larg < (long)dtls1_link_min_mtu())
222 return 0;
223 s->d1->link_mtu = larg;
224 return 1;
225 case DTLS_CTRL_GET_LINK_MIN_MTU:
226 return (long)dtls1_link_min_mtu();
227 case SSL_CTRL_SET_MTU:
228 /*
229 * We may not have a BIO set yet so can't call dtls1_min_mtu()
230 * We'll have to make do with dtls1_link_min_mtu() and max overhead
231 */
232 if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
233 return 0;
234 s->d1->mtu = larg;
235 return larg;
236 default:
237 ret = ssl3_ctrl(s, cmd, larg, parg);
238 break;
239 }
240 return ret;
241 }
242
dtls1_start_timer(SSL * s)243 void dtls1_start_timer(SSL *s)
244 {
245 unsigned int sec, usec;
246
247 #ifndef OPENSSL_NO_SCTP
248 /* Disable timer for SCTP */
249 if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
250 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
251 return;
252 }
253 #endif
254
255 /*
256 * If timer is not set, initialize duration with 1 second or
257 * a user-specified value if the timer callback is installed.
258 */
259 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
260
261 if (s->d1->timer_cb != NULL)
262 s->d1->timeout_duration_us = s->d1->timer_cb(s, 0);
263 else
264 s->d1->timeout_duration_us = 1000000;
265 }
266
267 /* Set timeout to current time */
268 get_current_time(&(s->d1->next_timeout));
269
270 /* Add duration to current time */
271
272 sec = s->d1->timeout_duration_us / 1000000;
273 usec = s->d1->timeout_duration_us - (sec * 1000000);
274
275 s->d1->next_timeout.tv_sec += sec;
276 s->d1->next_timeout.tv_usec += usec;
277
278 if (s->d1->next_timeout.tv_usec >= 1000000) {
279 s->d1->next_timeout.tv_sec++;
280 s->d1->next_timeout.tv_usec -= 1000000;
281 }
282
283 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
284 &(s->d1->next_timeout));
285 }
286
dtls1_get_timeout(SSL * s,struct timeval * timeleft)287 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
288 {
289 struct timeval timenow;
290
291 /* If no timeout is set, just return NULL */
292 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
293 return NULL;
294 }
295
296 /* Get current time */
297 get_current_time(&timenow);
298
299 /* If timer already expired, set remaining time to 0 */
300 if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
301 (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
302 s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
303 memset(timeleft, 0, sizeof(*timeleft));
304 return timeleft;
305 }
306
307 /* Calculate time left until timer expires */
308 memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
309 timeleft->tv_sec -= timenow.tv_sec;
310 timeleft->tv_usec -= timenow.tv_usec;
311 if (timeleft->tv_usec < 0) {
312 timeleft->tv_sec--;
313 timeleft->tv_usec += 1000000;
314 }
315
316 /*
317 * If remaining time is less than 15 ms, set it to 0 to prevent issues
318 * because of small divergences with socket timeouts.
319 */
320 if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
321 memset(timeleft, 0, sizeof(*timeleft));
322 }
323
324 return timeleft;
325 }
326
dtls1_is_timer_expired(SSL * s)327 int dtls1_is_timer_expired(SSL *s)
328 {
329 struct timeval timeleft;
330
331 /* Get time left until timeout, return false if no timer running */
332 if (dtls1_get_timeout(s, &timeleft) == NULL) {
333 return 0;
334 }
335
336 /* Return false if timer is not expired yet */
337 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
338 return 0;
339 }
340
341 /* Timer expired, so return true */
342 return 1;
343 }
344
dtls1_double_timeout(SSL * s)345 void dtls1_double_timeout(SSL *s)
346 {
347 s->d1->timeout_duration_us *= 2;
348 if (s->d1->timeout_duration_us > 60000000)
349 s->d1->timeout_duration_us = 60000000;
350 dtls1_start_timer(s);
351 }
352
dtls1_stop_timer(SSL * s)353 void dtls1_stop_timer(SSL *s)
354 {
355 /* Reset everything */
356 memset(&s->d1->timeout, 0, sizeof(s->d1->timeout));
357 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
358 s->d1->timeout_duration_us = 1000000;
359 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
360 &(s->d1->next_timeout));
361 /* Clear retransmission buffer */
362 dtls1_clear_sent_buffer(s);
363 }
364
dtls1_check_timeout_num(SSL * s)365 int dtls1_check_timeout_num(SSL *s)
366 {
367 size_t mtu;
368
369 s->d1->timeout.num_alerts++;
370
371 /* Reduce MTU after 2 unsuccessful retransmissions */
372 if (s->d1->timeout.num_alerts > 2
373 && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
374 mtu =
375 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
376 if (mtu < s->d1->mtu)
377 s->d1->mtu = mtu;
378 }
379
380 if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
381 /* fail the connection, enough alerts have been sent */
382 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_DTLS1_CHECK_TIMEOUT_NUM,
383 SSL_R_READ_TIMEOUT_EXPIRED);
384 return -1;
385 }
386
387 return 0;
388 }
389
dtls1_handle_timeout(SSL * s)390 int dtls1_handle_timeout(SSL *s)
391 {
392 /* if no timer is expired, don't do anything */
393 if (!dtls1_is_timer_expired(s)) {
394 return 0;
395 }
396
397 if (s->d1->timer_cb != NULL)
398 s->d1->timeout_duration_us = s->d1->timer_cb(s, s->d1->timeout_duration_us);
399 else
400 dtls1_double_timeout(s);
401
402 if (dtls1_check_timeout_num(s) < 0) {
403 /* SSLfatal() already called */
404 return -1;
405 }
406
407 s->d1->timeout.read_timeouts++;
408 if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
409 s->d1->timeout.read_timeouts = 1;
410 }
411
412 dtls1_start_timer(s);
413 /* Calls SSLfatal() if required */
414 return dtls1_retransmit_buffered_messages(s);
415 }
416
get_current_time(struct timeval * t)417 static void get_current_time(struct timeval *t)
418 {
419 #if defined(_WIN32)
420 SYSTEMTIME st;
421 union {
422 unsigned __int64 ul;
423 FILETIME ft;
424 } now;
425
426 GetSystemTime(&st);
427 SystemTimeToFileTime(&st, &now.ft);
428 /* re-bias to 1/1/1970 */
429 # ifdef __MINGW32__
430 now.ul -= 116444736000000000ULL;
431 # else
432 /* *INDENT-OFF* */
433 now.ul -= 116444736000000000UI64;
434 /* *INDENT-ON* */
435 # endif
436 t->tv_sec = (long)(now.ul / 10000000);
437 t->tv_usec = ((int)(now.ul % 10000000)) / 10;
438 #else
439 gettimeofday(t, NULL);
440 #endif
441 }
442
443 #define LISTEN_SUCCESS 2
444 #define LISTEN_SEND_VERIFY_REQUEST 1
445
446 #ifndef OPENSSL_NO_SOCK
DTLSv1_listen(SSL * s,BIO_ADDR * client)447 int DTLSv1_listen(SSL *s, BIO_ADDR *client)
448 {
449 int next, n, ret = 0;
450 unsigned char cookie[DTLS1_COOKIE_LENGTH];
451 unsigned char seq[SEQ_NUM_SIZE];
452 const unsigned char *data;
453 unsigned char *buf, *wbuf;
454 size_t fragoff, fraglen, msglen, reclen, align = 0;
455 unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen;
456 BIO *rbio, *wbio;
457 BIO_ADDR *tmpclient = NULL;
458 PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
459
460 if (s->handshake_func == NULL) {
461 /* Not properly initialized yet */
462 SSL_set_accept_state(s);
463 }
464
465 /* Ensure there is no state left over from a previous invocation */
466 if (!SSL_clear(s))
467 return -1;
468
469 ERR_clear_error();
470
471 rbio = SSL_get_rbio(s);
472 wbio = SSL_get_wbio(s);
473
474 if (!rbio || !wbio) {
475 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BIO_NOT_SET);
476 return -1;
477 }
478
479 /*
480 * Note: This check deliberately excludes DTLS1_BAD_VER because that version
481 * requires the MAC to be calculated *including* the first ClientHello
482 * (without the cookie). Since DTLSv1_listen is stateless that cannot be
483 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
484 * SSL_accept)
485 */
486 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
487 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION);
488 return -1;
489 }
490
491 if (!ssl3_setup_buffers(s)) {
492 /* SSLerr already called */
493 return -1;
494 }
495 buf = RECORD_LAYER_get_rbuf(&s->rlayer)->buf;
496 wbuf = RECORD_LAYER_get_wbuf(&s->rlayer)[0].buf;
497 #if defined(SSL3_ALIGN_PAYLOAD)
498 # if SSL3_ALIGN_PAYLOAD != 0
499 /*
500 * Using SSL3_RT_HEADER_LENGTH here instead of DTLS1_RT_HEADER_LENGTH for
501 * consistency with ssl3_read_n. In practice it should make no difference
502 * for sensible values of SSL3_ALIGN_PAYLOAD because the difference between
503 * SSL3_RT_HEADER_LENGTH and DTLS1_RT_HEADER_LENGTH is exactly 8
504 */
505 align = (size_t)buf + SSL3_RT_HEADER_LENGTH;
506 align = SSL3_ALIGN_PAYLOAD - 1 - ((align - 1) % SSL3_ALIGN_PAYLOAD);
507 # endif
508 #endif
509 buf += align;
510
511 do {
512 /* Get a packet */
513
514 clear_sys_error();
515 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH
516 + DTLS1_RT_HEADER_LENGTH);
517 if (n <= 0) {
518 if (BIO_should_retry(rbio)) {
519 /* Non-blocking IO */
520 goto end;
521 }
522 return -1;
523 }
524
525 if (!PACKET_buf_init(&pkt, buf, n)) {
526 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
527 return -1;
528 }
529
530 /*
531 * Parse the received record. If there are any problems with it we just
532 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
533 * resilient in the face of invalid records (e.g., invalid formatting,
534 * length, MAC, etc.). In general, invalid records SHOULD be silently
535 * discarded, thus preserving the association; however, an error MAY be
536 * logged for diagnostic purposes."
537 */
538
539 /* this packet contained a partial record, dump it */
540 if (n < DTLS1_RT_HEADER_LENGTH) {
541 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL);
542 goto end;
543 }
544
545 if (s->msg_callback)
546 s->msg_callback(0, 0, SSL3_RT_HEADER, buf,
547 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
548
549 /* Get the record header */
550 if (!PACKET_get_1(&pkt, &rectype)
551 || !PACKET_get_1(&pkt, &versmajor)) {
552 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
553 goto end;
554 }
555
556 if (rectype != SSL3_RT_HANDSHAKE) {
557 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
558 goto end;
559 }
560
561 /*
562 * Check record version number. We only check that the major version is
563 * the same.
564 */
565 if (versmajor != DTLS1_VERSION_MAJOR) {
566 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
567 goto end;
568 }
569
570 if (!PACKET_forward(&pkt, 1)
571 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */
572 || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
573 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
574 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
575 goto end;
576 }
577 reclen = PACKET_remaining(&msgpkt);
578 /*
579 * We allow data remaining at the end of the packet because there could
580 * be a second record (but we ignore it)
581 */
582
583 /* This is an initial ClientHello so the epoch has to be 0 */
584 if (seq[0] != 0 || seq[1] != 0) {
585 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
586 goto end;
587 }
588
589 /* Get a pointer to the raw message for the later callback */
590 data = PACKET_data(&msgpkt);
591
592 /* Finished processing the record header, now process the message */
593 if (!PACKET_get_1(&msgpkt, &msgtype)
594 || !PACKET_get_net_3_len(&msgpkt, &msglen)
595 || !PACKET_get_net_2(&msgpkt, &msgseq)
596 || !PACKET_get_net_3_len(&msgpkt, &fragoff)
597 || !PACKET_get_net_3_len(&msgpkt, &fraglen)
598 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
599 || PACKET_remaining(&msgpkt) != 0) {
600 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
601 goto end;
602 }
603
604 if (msgtype != SSL3_MT_CLIENT_HELLO) {
605 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
606 goto end;
607 }
608
609 /* Message sequence number can only be 0 or 1 */
610 if (msgseq > 2) {
611 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER);
612 goto end;
613 }
614
615 /*
616 * We don't support fragment reassembly for ClientHellos whilst
617 * listening because that would require server side state (which is
618 * against the whole point of the ClientHello/HelloVerifyRequest
619 * mechanism). Instead we only look at the first ClientHello fragment
620 * and require that the cookie must be contained within it.
621 */
622 if (fragoff != 0 || fraglen > msglen) {
623 /* Non initial ClientHello fragment (or bad fragment) */
624 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO);
625 goto end;
626 }
627
628 if (s->msg_callback)
629 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
630 fraglen + DTLS1_HM_HEADER_LENGTH, s,
631 s->msg_callback_arg);
632
633 if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
634 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
635 goto end;
636 }
637
638 /*
639 * Verify client version is supported
640 */
641 if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
642 s->method->version != DTLS_ANY_VERSION) {
643 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER);
644 goto end;
645 }
646
647 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
648 || !PACKET_get_length_prefixed_1(&msgpayload, &session)
649 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
650 /*
651 * Could be malformed or the cookie does not fit within the initial
652 * ClientHello fragment. Either way we can't handle it.
653 */
654 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
655 goto end;
656 }
657
658 /*
659 * Check if we have a cookie or not. If not we need to send a
660 * HelloVerifyRequest.
661 */
662 if (PACKET_remaining(&cookiepkt) == 0) {
663 next = LISTEN_SEND_VERIFY_REQUEST;
664 } else {
665 /*
666 * We have a cookie, so lets check it.
667 */
668 if (s->ctx->app_verify_cookie_cb == NULL) {
669 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
670 /* This is fatal */
671 return -1;
672 }
673 if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
674 (unsigned int)PACKET_remaining(&cookiepkt)) == 0) {
675 /*
676 * We treat invalid cookies in the same was as no cookie as
677 * per RFC6347
678 */
679 next = LISTEN_SEND_VERIFY_REQUEST;
680 } else {
681 /* Cookie verification succeeded */
682 next = LISTEN_SUCCESS;
683 }
684 }
685
686 if (next == LISTEN_SEND_VERIFY_REQUEST) {
687 WPACKET wpkt;
688 unsigned int version;
689 size_t wreclen;
690
691 /*
692 * There was no cookie in the ClientHello so we need to send a
693 * HelloVerifyRequest. If this fails we do not worry about trying
694 * to resend, we just drop it.
695 */
696
697 /* Generate the cookie */
698 if (s->ctx->app_gen_cookie_cb == NULL ||
699 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
700 cookielen > 255) {
701 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
702 /* This is fatal */
703 return -1;
704 }
705
706 /*
707 * Special case: for hello verify request, client version 1.0 and we
708 * haven't decided which version to use yet send back using version
709 * 1.0 header: otherwise some clients will ignore it.
710 */
711 version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
712 : s->version;
713
714 /* Construct the record and message headers */
715 if (!WPACKET_init_static_len(&wpkt,
716 wbuf,
717 ssl_get_max_send_fragment(s)
718 + DTLS1_RT_HEADER_LENGTH,
719 0)
720 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
721 || !WPACKET_put_bytes_u16(&wpkt, version)
722 /*
723 * Record sequence number is always the same as in the
724 * received ClientHello
725 */
726 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
727 /* End of record, start sub packet for message */
728 || !WPACKET_start_sub_packet_u16(&wpkt)
729 /* Message type */
730 || !WPACKET_put_bytes_u8(&wpkt,
731 DTLS1_MT_HELLO_VERIFY_REQUEST)
732 /*
733 * Message length - doesn't follow normal TLS convention:
734 * the length isn't the last thing in the message header.
735 * We'll need to fill this in later when we know the
736 * length. Set it to zero for now
737 */
738 || !WPACKET_put_bytes_u24(&wpkt, 0)
739 /*
740 * Message sequence number is always 0 for a
741 * HelloVerifyRequest
742 */
743 || !WPACKET_put_bytes_u16(&wpkt, 0)
744 /*
745 * We never fragment a HelloVerifyRequest, so fragment
746 * offset is 0
747 */
748 || !WPACKET_put_bytes_u24(&wpkt, 0)
749 /*
750 * Fragment length is the same as message length, but
751 * this *is* the last thing in the message header so we
752 * can just start a sub-packet. No need to come back
753 * later for this one.
754 */
755 || !WPACKET_start_sub_packet_u24(&wpkt)
756 /* Create the actual HelloVerifyRequest body */
757 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
758 /* Close message body */
759 || !WPACKET_close(&wpkt)
760 /* Close record body */
761 || !WPACKET_close(&wpkt)
762 || !WPACKET_get_total_written(&wpkt, &wreclen)
763 || !WPACKET_finish(&wpkt)) {
764 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
765 WPACKET_cleanup(&wpkt);
766 /* This is fatal */
767 return -1;
768 }
769
770 /*
771 * Fix up the message len in the message header. Its the same as the
772 * fragment len which has been filled in by WPACKET, so just copy
773 * that. Destination for the message len is after the record header
774 * plus one byte for the message content type. The source is the
775 * last 3 bytes of the message header
776 */
777 memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1],
778 &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
779 3);
780
781 if (s->msg_callback)
782 s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
783 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
784
785 if ((tmpclient = BIO_ADDR_new()) == NULL) {
786 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
787 goto end;
788 }
789
790 /*
791 * This is unnecessary if rbio and wbio are one and the same - but
792 * maybe they're not. We ignore errors here - some BIOs do not
793 * support this.
794 */
795 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
796 (void)BIO_dgram_set_peer(wbio, tmpclient);
797 }
798 BIO_ADDR_free(tmpclient);
799 tmpclient = NULL;
800
801 /* TODO(size_t): convert this call */
802 if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) {
803 if (BIO_should_retry(wbio)) {
804 /*
805 * Non-blocking IO...but we're stateless, so we're just
806 * going to drop this packet.
807 */
808 goto end;
809 }
810 return -1;
811 }
812
813 if (BIO_flush(wbio) <= 0) {
814 if (BIO_should_retry(wbio)) {
815 /*
816 * Non-blocking IO...but we're stateless, so we're just
817 * going to drop this packet.
818 */
819 goto end;
820 }
821 return -1;
822 }
823 }
824 } while (next != LISTEN_SUCCESS);
825
826 /*
827 * Set expected sequence numbers to continue the handshake.
828 */
829 s->d1->handshake_read_seq = 1;
830 s->d1->handshake_write_seq = 1;
831 s->d1->next_handshake_write_seq = 1;
832 DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
833
834 /*
835 * We are doing cookie exchange, so make sure we set that option in the
836 * SSL object
837 */
838 SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
839
840 /*
841 * Tell the state machine that we've done the initial hello verify
842 * exchange
843 */
844 ossl_statem_set_hello_verify_done(s);
845
846 /*
847 * Some BIOs may not support this. If we fail we clear the client address
848 */
849 if (BIO_dgram_get_peer(rbio, client) <= 0)
850 BIO_ADDR_clear(client);
851
852 /* Buffer the record in the processed_rcds queue */
853 if (!dtls_buffer_listen_record(s, reclen, seq, align))
854 return -1;
855
856 ret = 1;
857 end:
858 BIO_ADDR_free(tmpclient);
859 return ret;
860 }
861 #endif
862
dtls1_handshake_write(SSL * s)863 static int dtls1_handshake_write(SSL *s)
864 {
865 return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
866 }
867
dtls1_shutdown(SSL * s)868 int dtls1_shutdown(SSL *s)
869 {
870 int ret;
871 #ifndef OPENSSL_NO_SCTP
872 BIO *wbio;
873
874 wbio = SSL_get_wbio(s);
875 if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
876 !(s->shutdown & SSL_SENT_SHUTDOWN)) {
877 ret = BIO_dgram_sctp_wait_for_dry(wbio);
878 if (ret < 0)
879 return -1;
880
881 if (ret == 0)
882 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
883 NULL);
884 }
885 #endif
886 ret = ssl3_shutdown(s);
887 #ifndef OPENSSL_NO_SCTP
888 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
889 #endif
890 return ret;
891 }
892
dtls1_query_mtu(SSL * s)893 int dtls1_query_mtu(SSL *s)
894 {
895 if (s->d1->link_mtu) {
896 s->d1->mtu =
897 s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
898 s->d1->link_mtu = 0;
899 }
900
901 /* AHA! Figure out the MTU, and stick to the right size */
902 if (s->d1->mtu < dtls1_min_mtu(s)) {
903 if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
904 s->d1->mtu =
905 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
906
907 /*
908 * I've seen the kernel return bogus numbers when it doesn't know
909 * (initial write), so just make sure we have a reasonable number
910 */
911 if (s->d1->mtu < dtls1_min_mtu(s)) {
912 /* Set to min mtu */
913 s->d1->mtu = dtls1_min_mtu(s);
914 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
915 (long)s->d1->mtu, NULL);
916 }
917 } else
918 return 0;
919 }
920 return 1;
921 }
922
dtls1_link_min_mtu(void)923 static size_t dtls1_link_min_mtu(void)
924 {
925 return (g_probable_mtu[(sizeof(g_probable_mtu) /
926 sizeof(g_probable_mtu[0])) - 1]);
927 }
928
dtls1_min_mtu(SSL * s)929 size_t dtls1_min_mtu(SSL *s)
930 {
931 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
932 }
933
DTLS_get_data_mtu(const SSL * s)934 size_t DTLS_get_data_mtu(const SSL *s)
935 {
936 size_t mac_overhead, int_overhead, blocksize, ext_overhead;
937 const SSL_CIPHER *ciph = SSL_get_current_cipher(s);
938 size_t mtu = s->d1->mtu;
939
940 if (ciph == NULL)
941 return 0;
942
943 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
944 &blocksize, &ext_overhead))
945 return 0;
946
947 if (SSL_READ_ETM(s))
948 ext_overhead += mac_overhead;
949 else
950 int_overhead += mac_overhead;
951
952 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */
953 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
954 return 0;
955 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
956
957 /* Round encrypted payload down to cipher block size (for CBC etc.)
958 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
959 if (blocksize)
960 mtu -= (mtu % blocksize);
961
962 /* Subtract internal overhead (e.g. CBC padding len byte) */
963 if (int_overhead >= mtu)
964 return 0;
965 mtu -= int_overhead;
966
967 return mtu;
968 }
969
DTLS_set_timer_cb(SSL * s,DTLS_timer_cb cb)970 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb)
971 {
972 s->d1->timer_cb = cb;
973 }
974