1 /* 2 * Copyright 2005-2017 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_locl.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 dtls1_clear_queues(s); 146 147 pqueue_free(s->d1->buffered_messages); 148 pqueue_free(s->d1->sent_messages); 149 150 OPENSSL_free(s->d1); 151 s->d1 = NULL; 152 } 153 154 int dtls1_clear(SSL *s) 155 { 156 pqueue *buffered_messages; 157 pqueue *sent_messages; 158 size_t mtu; 159 size_t link_mtu; 160 161 DTLS_RECORD_LAYER_clear(&s->rlayer); 162 163 if (s->d1) { 164 DTLS_timer_cb timer_cb = s->d1->timer_cb; 165 166 buffered_messages = s->d1->buffered_messages; 167 sent_messages = s->d1->sent_messages; 168 mtu = s->d1->mtu; 169 link_mtu = s->d1->link_mtu; 170 171 dtls1_clear_queues(s); 172 173 memset(s->d1, 0, sizeof(*s->d1)); 174 175 /* Restore the timer callback from previous state */ 176 s->d1->timer_cb = timer_cb; 177 178 if (s->server) { 179 s->d1->cookie_len = sizeof(s->d1->cookie); 180 } 181 182 if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) { 183 s->d1->mtu = mtu; 184 s->d1->link_mtu = link_mtu; 185 } 186 187 s->d1->buffered_messages = buffered_messages; 188 s->d1->sent_messages = sent_messages; 189 } 190 191 if (!ssl3_clear(s)) 192 return 0; 193 194 if (s->method->version == DTLS_ANY_VERSION) 195 s->version = DTLS_MAX_VERSION; 196 #ifndef OPENSSL_NO_DTLS1_METHOD 197 else if (s->options & SSL_OP_CISCO_ANYCONNECT) 198 s->client_version = s->version = DTLS1_BAD_VER; 199 #endif 200 else 201 s->version = s->method->version; 202 203 return 1; 204 } 205 206 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg) 207 { 208 int ret = 0; 209 210 switch (cmd) { 211 case DTLS_CTRL_GET_TIMEOUT: 212 if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) { 213 ret = 1; 214 } 215 break; 216 case DTLS_CTRL_HANDLE_TIMEOUT: 217 ret = dtls1_handle_timeout(s); 218 break; 219 case DTLS_CTRL_SET_LINK_MTU: 220 if (larg < (long)dtls1_link_min_mtu()) 221 return 0; 222 s->d1->link_mtu = larg; 223 return 1; 224 case DTLS_CTRL_GET_LINK_MIN_MTU: 225 return (long)dtls1_link_min_mtu(); 226 case SSL_CTRL_SET_MTU: 227 /* 228 * We may not have a BIO set yet so can't call dtls1_min_mtu() 229 * We'll have to make do with dtls1_link_min_mtu() and max overhead 230 */ 231 if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD) 232 return 0; 233 s->d1->mtu = larg; 234 return larg; 235 default: 236 ret = ssl3_ctrl(s, cmd, larg, parg); 237 break; 238 } 239 return ret; 240 } 241 242 void dtls1_start_timer(SSL *s) 243 { 244 unsigned int sec, usec; 245 246 #ifndef OPENSSL_NO_SCTP 247 /* Disable timer for SCTP */ 248 if (BIO_dgram_is_sctp(SSL_get_wbio(s))) { 249 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout)); 250 return; 251 } 252 #endif 253 254 /* 255 * If timer is not set, initialize duration with 1 second or 256 * a user-specified value if the timer callback is installed. 257 */ 258 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) { 259 260 if (s->d1->timer_cb != NULL) 261 s->d1->timeout_duration_us = s->d1->timer_cb(s, 0); 262 else 263 s->d1->timeout_duration_us = 1000000; 264 } 265 266 /* Set timeout to current time */ 267 get_current_time(&(s->d1->next_timeout)); 268 269 /* Add duration to current time */ 270 271 sec = s->d1->timeout_duration_us / 1000000; 272 usec = s->d1->timeout_duration_us - (sec * 1000000); 273 274 s->d1->next_timeout.tv_sec += sec; 275 s->d1->next_timeout.tv_usec += usec; 276 277 if (s->d1->next_timeout.tv_usec >= 1000000) { 278 s->d1->next_timeout.tv_sec++; 279 s->d1->next_timeout.tv_usec -= 1000000; 280 } 281 282 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 283 &(s->d1->next_timeout)); 284 } 285 286 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft) 287 { 288 struct timeval timenow; 289 290 /* If no timeout is set, just return NULL */ 291 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) { 292 return NULL; 293 } 294 295 /* Get current time */ 296 get_current_time(&timenow); 297 298 /* If timer already expired, set remaining time to 0 */ 299 if (s->d1->next_timeout.tv_sec < timenow.tv_sec || 300 (s->d1->next_timeout.tv_sec == timenow.tv_sec && 301 s->d1->next_timeout.tv_usec <= timenow.tv_usec)) { 302 memset(timeleft, 0, sizeof(*timeleft)); 303 return timeleft; 304 } 305 306 /* Calculate time left until timer expires */ 307 memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval)); 308 timeleft->tv_sec -= timenow.tv_sec; 309 timeleft->tv_usec -= timenow.tv_usec; 310 if (timeleft->tv_usec < 0) { 311 timeleft->tv_sec--; 312 timeleft->tv_usec += 1000000; 313 } 314 315 /* 316 * If remaining time is less than 15 ms, set it to 0 to prevent issues 317 * because of small divergences with socket timeouts. 318 */ 319 if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) { 320 memset(timeleft, 0, sizeof(*timeleft)); 321 } 322 323 return timeleft; 324 } 325 326 int dtls1_is_timer_expired(SSL *s) 327 { 328 struct timeval timeleft; 329 330 /* Get time left until timeout, return false if no timer running */ 331 if (dtls1_get_timeout(s, &timeleft) == NULL) { 332 return 0; 333 } 334 335 /* Return false if timer is not expired yet */ 336 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) { 337 return 0; 338 } 339 340 /* Timer expired, so return true */ 341 return 1; 342 } 343 344 void dtls1_double_timeout(SSL *s) 345 { 346 s->d1->timeout_duration_us *= 2; 347 if (s->d1->timeout_duration_us > 60000000) 348 s->d1->timeout_duration_us = 60000000; 349 dtls1_start_timer(s); 350 } 351 352 void dtls1_stop_timer(SSL *s) 353 { 354 /* Reset everything */ 355 memset(&s->d1->timeout, 0, sizeof(s->d1->timeout)); 356 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout)); 357 s->d1->timeout_duration_us = 1000000; 358 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 359 &(s->d1->next_timeout)); 360 /* Clear retransmission buffer */ 361 dtls1_clear_sent_buffer(s); 362 } 363 364 int dtls1_check_timeout_num(SSL *s) 365 { 366 size_t mtu; 367 368 s->d1->timeout.num_alerts++; 369 370 /* Reduce MTU after 2 unsuccessful retransmissions */ 371 if (s->d1->timeout.num_alerts > 2 372 && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 373 mtu = 374 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL); 375 if (mtu < s->d1->mtu) 376 s->d1->mtu = mtu; 377 } 378 379 if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) { 380 /* fail the connection, enough alerts have been sent */ 381 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_DTLS1_CHECK_TIMEOUT_NUM, 382 SSL_R_READ_TIMEOUT_EXPIRED); 383 return -1; 384 } 385 386 return 0; 387 } 388 389 int dtls1_handle_timeout(SSL *s) 390 { 391 /* if no timer is expired, don't do anything */ 392 if (!dtls1_is_timer_expired(s)) { 393 return 0; 394 } 395 396 if (s->d1->timer_cb != NULL) 397 s->d1->timeout_duration_us = s->d1->timer_cb(s, s->d1->timeout_duration_us); 398 else 399 dtls1_double_timeout(s); 400 401 if (dtls1_check_timeout_num(s) < 0) { 402 /* SSLfatal() already called */ 403 return -1; 404 } 405 406 s->d1->timeout.read_timeouts++; 407 if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) { 408 s->d1->timeout.read_timeouts = 1; 409 } 410 411 dtls1_start_timer(s); 412 /* Calls SSLfatal() if required */ 413 return dtls1_retransmit_buffered_messages(s); 414 } 415 416 static void get_current_time(struct timeval *t) 417 { 418 #if defined(_WIN32) 419 SYSTEMTIME st; 420 union { 421 unsigned __int64 ul; 422 FILETIME ft; 423 } now; 424 425 GetSystemTime(&st); 426 SystemTimeToFileTime(&st, &now.ft); 427 /* re-bias to 1/1/1970 */ 428 # ifdef __MINGW32__ 429 now.ul -= 116444736000000000ULL; 430 # else 431 /* *INDENT-OFF* */ 432 now.ul -= 116444736000000000UI64; 433 /* *INDENT-ON* */ 434 # endif 435 t->tv_sec = (long)(now.ul / 10000000); 436 t->tv_usec = ((int)(now.ul % 10000000)) / 10; 437 #else 438 gettimeofday(t, NULL); 439 #endif 440 } 441 442 #define LISTEN_SUCCESS 2 443 #define LISTEN_SEND_VERIFY_REQUEST 1 444 445 #ifndef OPENSSL_NO_SOCK 446 int DTLSv1_listen(SSL *s, BIO_ADDR *client) 447 { 448 int next, n, ret = 0, clearpkt = 0; 449 unsigned char cookie[DTLS1_COOKIE_LENGTH]; 450 unsigned char seq[SEQ_NUM_SIZE]; 451 const unsigned char *data; 452 unsigned char *buf; 453 size_t fragoff, fraglen, msglen; 454 unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen; 455 BIO *rbio, *wbio; 456 BUF_MEM *bufm; 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 * We only peek at incoming ClientHello's until we're sure we are going to 481 * to respond with a HelloVerifyRequest. If its a ClientHello with a valid 482 * cookie then we leave it in the BIO for accept to handle. 483 */ 484 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL); 485 486 /* 487 * Note: This check deliberately excludes DTLS1_BAD_VER because that version 488 * requires the MAC to be calculated *including* the first ClientHello 489 * (without the cookie). Since DTLSv1_listen is stateless that cannot be 490 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via 491 * SSL_accept) 492 */ 493 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) { 494 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION); 495 return -1; 496 } 497 498 if (s->init_buf == NULL) { 499 if ((bufm = BUF_MEM_new()) == NULL) { 500 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE); 501 return -1; 502 } 503 504 if (!BUF_MEM_grow(bufm, SSL3_RT_MAX_PLAIN_LENGTH)) { 505 BUF_MEM_free(bufm); 506 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE); 507 return -1; 508 } 509 s->init_buf = bufm; 510 } 511 buf = (unsigned char *)s->init_buf->data; 512 513 do { 514 /* Get a packet */ 515 516 clear_sys_error(); 517 /* 518 * Technically a ClientHello could be SSL3_RT_MAX_PLAIN_LENGTH 519 * + DTLS1_RT_HEADER_LENGTH bytes long. Normally init_buf does not store 520 * the record header as well, but we do here. We've set up init_buf to 521 * be the standard size for simplicity. In practice we shouldn't ever 522 * receive a ClientHello as long as this. If we do it will get dropped 523 * in the record length check below. 524 */ 525 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH); 526 527 if (n <= 0) { 528 if (BIO_should_retry(rbio)) { 529 /* Non-blocking IO */ 530 goto end; 531 } 532 return -1; 533 } 534 535 /* If we hit any problems we need to clear this packet from the BIO */ 536 clearpkt = 1; 537 538 if (!PACKET_buf_init(&pkt, buf, n)) { 539 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR); 540 return -1; 541 } 542 543 /* 544 * Parse the received record. If there are any problems with it we just 545 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is 546 * resilient in the face of invalid records (e.g., invalid formatting, 547 * length, MAC, etc.). In general, invalid records SHOULD be silently 548 * discarded, thus preserving the association; however, an error MAY be 549 * logged for diagnostic purposes." 550 */ 551 552 /* this packet contained a partial record, dump it */ 553 if (n < DTLS1_RT_HEADER_LENGTH) { 554 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL); 555 goto end; 556 } 557 558 if (s->msg_callback) 559 s->msg_callback(0, 0, SSL3_RT_HEADER, buf, 560 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 561 562 /* Get the record header */ 563 if (!PACKET_get_1(&pkt, &rectype) 564 || !PACKET_get_1(&pkt, &versmajor)) { 565 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 566 goto end; 567 } 568 569 if (rectype != SSL3_RT_HANDSHAKE) { 570 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 571 goto end; 572 } 573 574 /* 575 * Check record version number. We only check that the major version is 576 * the same. 577 */ 578 if (versmajor != DTLS1_VERSION_MAJOR) { 579 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER); 580 goto end; 581 } 582 583 if (!PACKET_forward(&pkt, 1) 584 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */ 585 || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE) 586 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) { 587 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 588 goto end; 589 } 590 /* 591 * We allow data remaining at the end of the packet because there could 592 * be a second record (but we ignore it) 593 */ 594 595 /* This is an initial ClientHello so the epoch has to be 0 */ 596 if (seq[0] != 0 || seq[1] != 0) { 597 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 598 goto end; 599 } 600 601 /* Get a pointer to the raw message for the later callback */ 602 data = PACKET_data(&msgpkt); 603 604 /* Finished processing the record header, now process the message */ 605 if (!PACKET_get_1(&msgpkt, &msgtype) 606 || !PACKET_get_net_3_len(&msgpkt, &msglen) 607 || !PACKET_get_net_2(&msgpkt, &msgseq) 608 || !PACKET_get_net_3_len(&msgpkt, &fragoff) 609 || !PACKET_get_net_3_len(&msgpkt, &fraglen) 610 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen) 611 || PACKET_remaining(&msgpkt) != 0) { 612 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 613 goto end; 614 } 615 616 if (msgtype != SSL3_MT_CLIENT_HELLO) { 617 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 618 goto end; 619 } 620 621 /* Message sequence number can only be 0 or 1 */ 622 if (msgseq > 2) { 623 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER); 624 goto end; 625 } 626 627 /* 628 * We don't support fragment reassembly for ClientHellos whilst 629 * listening because that would require server side state (which is 630 * against the whole point of the ClientHello/HelloVerifyRequest 631 * mechanism). Instead we only look at the first ClientHello fragment 632 * and require that the cookie must be contained within it. 633 */ 634 if (fragoff != 0 || fraglen > msglen) { 635 /* Non initial ClientHello fragment (or bad fragment) */ 636 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO); 637 goto end; 638 } 639 640 if (s->msg_callback) 641 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data, 642 fraglen + DTLS1_HM_HEADER_LENGTH, s, 643 s->msg_callback_arg); 644 645 if (!PACKET_get_net_2(&msgpayload, &clientvers)) { 646 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 647 goto end; 648 } 649 650 /* 651 * Verify client version is supported 652 */ 653 if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) && 654 s->method->version != DTLS_ANY_VERSION) { 655 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER); 656 goto end; 657 } 658 659 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE) 660 || !PACKET_get_length_prefixed_1(&msgpayload, &session) 661 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) { 662 /* 663 * Could be malformed or the cookie does not fit within the initial 664 * ClientHello fragment. Either way we can't handle it. 665 */ 666 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 667 goto end; 668 } 669 670 /* 671 * Check if we have a cookie or not. If not we need to send a 672 * HelloVerifyRequest. 673 */ 674 if (PACKET_remaining(&cookiepkt) == 0) { 675 next = LISTEN_SEND_VERIFY_REQUEST; 676 } else { 677 /* 678 * We have a cookie, so lets check it. 679 */ 680 if (s->ctx->app_verify_cookie_cb == NULL) { 681 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK); 682 /* This is fatal */ 683 return -1; 684 } 685 if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt), 686 (unsigned int)PACKET_remaining(&cookiepkt)) == 0) { 687 /* 688 * We treat invalid cookies in the same was as no cookie as 689 * per RFC6347 690 */ 691 next = LISTEN_SEND_VERIFY_REQUEST; 692 } else { 693 /* Cookie verification succeeded */ 694 next = LISTEN_SUCCESS; 695 } 696 } 697 698 if (next == LISTEN_SEND_VERIFY_REQUEST) { 699 WPACKET wpkt; 700 unsigned int version; 701 size_t wreclen; 702 703 /* 704 * There was no cookie in the ClientHello so we need to send a 705 * HelloVerifyRequest. If this fails we do not worry about trying 706 * to resend, we just drop it. 707 */ 708 709 /* 710 * Dump the read packet, we don't need it any more. Ignore return 711 * value 712 */ 713 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL); 714 BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH); 715 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL); 716 717 /* Generate the cookie */ 718 if (s->ctx->app_gen_cookie_cb == NULL || 719 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 || 720 cookielen > 255) { 721 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE); 722 /* This is fatal */ 723 return -1; 724 } 725 726 /* 727 * Special case: for hello verify request, client version 1.0 and we 728 * haven't decided which version to use yet send back using version 729 * 1.0 header: otherwise some clients will ignore it. 730 */ 731 version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION 732 : s->version; 733 734 /* Construct the record and message headers */ 735 if (!WPACKET_init(&wpkt, s->init_buf) 736 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE) 737 || !WPACKET_put_bytes_u16(&wpkt, version) 738 /* 739 * Record sequence number is always the same as in the 740 * received ClientHello 741 */ 742 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE) 743 /* End of record, start sub packet for message */ 744 || !WPACKET_start_sub_packet_u16(&wpkt) 745 /* Message type */ 746 || !WPACKET_put_bytes_u8(&wpkt, 747 DTLS1_MT_HELLO_VERIFY_REQUEST) 748 /* 749 * Message length - doesn't follow normal TLS convention: 750 * the length isn't the last thing in the message header. 751 * We'll need to fill this in later when we know the 752 * length. Set it to zero for now 753 */ 754 || !WPACKET_put_bytes_u24(&wpkt, 0) 755 /* 756 * Message sequence number is always 0 for a 757 * HelloVerifyRequest 758 */ 759 || !WPACKET_put_bytes_u16(&wpkt, 0) 760 /* 761 * We never fragment a HelloVerifyRequest, so fragment 762 * offset is 0 763 */ 764 || !WPACKET_put_bytes_u24(&wpkt, 0) 765 /* 766 * Fragment length is the same as message length, but 767 * this *is* the last thing in the message header so we 768 * can just start a sub-packet. No need to come back 769 * later for this one. 770 */ 771 || !WPACKET_start_sub_packet_u24(&wpkt) 772 /* Create the actual HelloVerifyRequest body */ 773 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen) 774 /* Close message body */ 775 || !WPACKET_close(&wpkt) 776 /* Close record body */ 777 || !WPACKET_close(&wpkt) 778 || !WPACKET_get_total_written(&wpkt, &wreclen) 779 || !WPACKET_finish(&wpkt)) { 780 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR); 781 WPACKET_cleanup(&wpkt); 782 /* This is fatal */ 783 return -1; 784 } 785 786 /* 787 * Fix up the message len in the message header. Its the same as the 788 * fragment len which has been filled in by WPACKET, so just copy 789 * that. Destination for the message len is after the record header 790 * plus one byte for the message content type. The source is the 791 * last 3 bytes of the message header 792 */ 793 memcpy(&buf[DTLS1_RT_HEADER_LENGTH + 1], 794 &buf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3], 795 3); 796 797 if (s->msg_callback) 798 s->msg_callback(1, 0, SSL3_RT_HEADER, buf, 799 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 800 801 if ((tmpclient = BIO_ADDR_new()) == NULL) { 802 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE); 803 goto end; 804 } 805 806 /* 807 * This is unnecessary if rbio and wbio are one and the same - but 808 * maybe they're not. We ignore errors here - some BIOs do not 809 * support this. 810 */ 811 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) { 812 (void)BIO_dgram_set_peer(wbio, tmpclient); 813 } 814 BIO_ADDR_free(tmpclient); 815 tmpclient = NULL; 816 817 /* TODO(size_t): convert this call */ 818 if (BIO_write(wbio, buf, wreclen) < (int)wreclen) { 819 if (BIO_should_retry(wbio)) { 820 /* 821 * Non-blocking IO...but we're stateless, so we're just 822 * going to drop this packet. 823 */ 824 goto end; 825 } 826 return -1; 827 } 828 829 if (BIO_flush(wbio) <= 0) { 830 if (BIO_should_retry(wbio)) { 831 /* 832 * Non-blocking IO...but we're stateless, so we're just 833 * going to drop this packet. 834 */ 835 goto end; 836 } 837 return -1; 838 } 839 } 840 } while (next != LISTEN_SUCCESS); 841 842 /* 843 * Set expected sequence numbers to continue the handshake. 844 */ 845 s->d1->handshake_read_seq = 1; 846 s->d1->handshake_write_seq = 1; 847 s->d1->next_handshake_write_seq = 1; 848 DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq); 849 850 /* 851 * We are doing cookie exchange, so make sure we set that option in the 852 * SSL object 853 */ 854 SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE); 855 856 /* 857 * Tell the state machine that we've done the initial hello verify 858 * exchange 859 */ 860 ossl_statem_set_hello_verify_done(s); 861 862 /* 863 * Some BIOs may not support this. If we fail we clear the client address 864 */ 865 if (BIO_dgram_get_peer(rbio, client) <= 0) 866 BIO_ADDR_clear(client); 867 868 ret = 1; 869 clearpkt = 0; 870 end: 871 BIO_ADDR_free(tmpclient); 872 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL); 873 if (clearpkt) { 874 /* Dump this packet. Ignore return value */ 875 BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH); 876 } 877 return ret; 878 } 879 #endif 880 881 static int dtls1_handshake_write(SSL *s) 882 { 883 return dtls1_do_write(s, SSL3_RT_HANDSHAKE); 884 } 885 886 int dtls1_shutdown(SSL *s) 887 { 888 int ret; 889 #ifndef OPENSSL_NO_SCTP 890 BIO *wbio; 891 892 wbio = SSL_get_wbio(s); 893 if (wbio != NULL && BIO_dgram_is_sctp(wbio) && 894 !(s->shutdown & SSL_SENT_SHUTDOWN)) { 895 ret = BIO_dgram_sctp_wait_for_dry(wbio); 896 if (ret < 0) 897 return -1; 898 899 if (ret == 0) 900 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1, 901 NULL); 902 } 903 #endif 904 ret = ssl3_shutdown(s); 905 #ifndef OPENSSL_NO_SCTP 906 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL); 907 #endif 908 return ret; 909 } 910 911 int dtls1_query_mtu(SSL *s) 912 { 913 if (s->d1->link_mtu) { 914 s->d1->mtu = 915 s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 916 s->d1->link_mtu = 0; 917 } 918 919 /* AHA! Figure out the MTU, and stick to the right size */ 920 if (s->d1->mtu < dtls1_min_mtu(s)) { 921 if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 922 s->d1->mtu = 923 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 924 925 /* 926 * I've seen the kernel return bogus numbers when it doesn't know 927 * (initial write), so just make sure we have a reasonable number 928 */ 929 if (s->d1->mtu < dtls1_min_mtu(s)) { 930 /* Set to min mtu */ 931 s->d1->mtu = dtls1_min_mtu(s); 932 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU, 933 (long)s->d1->mtu, NULL); 934 } 935 } else 936 return 0; 937 } 938 return 1; 939 } 940 941 static size_t dtls1_link_min_mtu(void) 942 { 943 return (g_probable_mtu[(sizeof(g_probable_mtu) / 944 sizeof(g_probable_mtu[0])) - 1]); 945 } 946 947 size_t dtls1_min_mtu(SSL *s) 948 { 949 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 950 } 951 952 size_t DTLS_get_data_mtu(const SSL *s) 953 { 954 size_t mac_overhead, int_overhead, blocksize, ext_overhead; 955 const SSL_CIPHER *ciph = SSL_get_current_cipher(s); 956 size_t mtu = s->d1->mtu; 957 958 if (ciph == NULL) 959 return 0; 960 961 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead, 962 &blocksize, &ext_overhead)) 963 return 0; 964 965 if (SSL_READ_ETM(s)) 966 ext_overhead += mac_overhead; 967 else 968 int_overhead += mac_overhead; 969 970 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */ 971 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu) 972 return 0; 973 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH; 974 975 /* Round encrypted payload down to cipher block size (for CBC etc.) 976 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */ 977 if (blocksize) 978 mtu -= (mtu % blocksize); 979 980 /* Subtract internal overhead (e.g. CBC padding len byte) */ 981 if (int_overhead >= mtu) 982 return 0; 983 mtu -= int_overhead; 984 985 return mtu; 986 } 987 988 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb) 989 { 990 s->d1->timer_cb = cb; 991 } 992