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 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 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 } 107 108 static void dtls1_clear_queues(SSL *s) 109 { 110 dtls1_clear_received_buffer(s); 111 dtls1_clear_sent_buffer(s); 112 } 113 114 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 } 125 126 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 } 137 138 139 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 } 154 155 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 } 206 207 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 } 242 243 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 } 286 287 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 } 326 327 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 } 344 345 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 } 352 353 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 } 364 365 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 } 389 390 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 } 416 417 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 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 862 863 static int dtls1_handshake_write(SSL *s) 864 { 865 return dtls1_do_write(s, SSL3_RT_HANDSHAKE); 866 } 867 868 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 } 892 893 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 } 922 923 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 } 928 929 size_t dtls1_min_mtu(SSL *s) 930 { 931 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 932 } 933 934 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 } 969 970 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb) 971 { 972 s->d1->timer_cb = cb; 973 } 974