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 static 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 } 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; 449 unsigned char cookie[DTLS1_COOKIE_LENGTH]; 450 unsigned char seq[SEQ_NUM_SIZE]; 451 const unsigned char *data; 452 unsigned char *buf, *wbuf; 453 size_t fragoff, fraglen, msglen, reclen, align = 0; 454 unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen; 455 BIO *rbio, *wbio; 456 BIO_ADDR *tmpclient = NULL; 457 PACKET pkt, msgpkt, msgpayload, session, cookiepkt; 458 459 if (s->handshake_func == NULL) { 460 /* Not properly initialized yet */ 461 SSL_set_accept_state(s); 462 } 463 464 /* Ensure there is no state left over from a previous invocation */ 465 if (!SSL_clear(s)) 466 return -1; 467 468 ERR_clear_error(); 469 470 rbio = SSL_get_rbio(s); 471 wbio = SSL_get_wbio(s); 472 473 if (!rbio || !wbio) { 474 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BIO_NOT_SET); 475 return -1; 476 } 477 478 /* 479 * Note: This check deliberately excludes DTLS1_BAD_VER because that version 480 * requires the MAC to be calculated *including* the first ClientHello 481 * (without the cookie). Since DTLSv1_listen is stateless that cannot be 482 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via 483 * SSL_accept) 484 */ 485 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) { 486 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION); 487 return -1; 488 } 489 490 if (!ssl3_setup_buffers(s)) { 491 /* SSLerr already called */ 492 return -1; 493 } 494 buf = RECORD_LAYER_get_rbuf(&s->rlayer)->buf; 495 wbuf = RECORD_LAYER_get_wbuf(&s->rlayer)[0].buf; 496 #if defined(SSL3_ALIGN_PAYLOAD) 497 # if SSL3_ALIGN_PAYLOAD != 0 498 /* 499 * Using SSL3_RT_HEADER_LENGTH here instead of DTLS1_RT_HEADER_LENGTH for 500 * consistency with ssl3_read_n. In practice it should make no difference 501 * for sensible values of SSL3_ALIGN_PAYLOAD because the difference between 502 * SSL3_RT_HEADER_LENGTH and DTLS1_RT_HEADER_LENGTH is exactly 8 503 */ 504 align = (size_t)buf + SSL3_RT_HEADER_LENGTH; 505 align = SSL3_ALIGN_PAYLOAD - 1 - ((align - 1) % SSL3_ALIGN_PAYLOAD); 506 # endif 507 #endif 508 buf += align; 509 510 do { 511 /* Get a packet */ 512 513 clear_sys_error(); 514 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH 515 + DTLS1_RT_HEADER_LENGTH); 516 if (n <= 0) { 517 if (BIO_should_retry(rbio)) { 518 /* Non-blocking IO */ 519 goto end; 520 } 521 return -1; 522 } 523 524 if (!PACKET_buf_init(&pkt, buf, n)) { 525 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR); 526 return -1; 527 } 528 529 /* 530 * Parse the received record. If there are any problems with it we just 531 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is 532 * resilient in the face of invalid records (e.g., invalid formatting, 533 * length, MAC, etc.). In general, invalid records SHOULD be silently 534 * discarded, thus preserving the association; however, an error MAY be 535 * logged for diagnostic purposes." 536 */ 537 538 /* this packet contained a partial record, dump it */ 539 if (n < DTLS1_RT_HEADER_LENGTH) { 540 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL); 541 goto end; 542 } 543 544 if (s->msg_callback) 545 s->msg_callback(0, 0, SSL3_RT_HEADER, buf, 546 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 547 548 /* Get the record header */ 549 if (!PACKET_get_1(&pkt, &rectype) 550 || !PACKET_get_1(&pkt, &versmajor)) { 551 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 552 goto end; 553 } 554 555 if (rectype != SSL3_RT_HANDSHAKE) { 556 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 557 goto end; 558 } 559 560 /* 561 * Check record version number. We only check that the major version is 562 * the same. 563 */ 564 if (versmajor != DTLS1_VERSION_MAJOR) { 565 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER); 566 goto end; 567 } 568 569 if (!PACKET_forward(&pkt, 1) 570 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */ 571 || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE) 572 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) { 573 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 574 goto end; 575 } 576 reclen = PACKET_remaining(&msgpkt); 577 /* 578 * We allow data remaining at the end of the packet because there could 579 * be a second record (but we ignore it) 580 */ 581 582 /* This is an initial ClientHello so the epoch has to be 0 */ 583 if (seq[0] != 0 || seq[1] != 0) { 584 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 585 goto end; 586 } 587 588 /* Get a pointer to the raw message for the later callback */ 589 data = PACKET_data(&msgpkt); 590 591 /* Finished processing the record header, now process the message */ 592 if (!PACKET_get_1(&msgpkt, &msgtype) 593 || !PACKET_get_net_3_len(&msgpkt, &msglen) 594 || !PACKET_get_net_2(&msgpkt, &msgseq) 595 || !PACKET_get_net_3_len(&msgpkt, &fragoff) 596 || !PACKET_get_net_3_len(&msgpkt, &fraglen) 597 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen) 598 || PACKET_remaining(&msgpkt) != 0) { 599 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 600 goto end; 601 } 602 603 if (msgtype != SSL3_MT_CLIENT_HELLO) { 604 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE); 605 goto end; 606 } 607 608 /* Message sequence number can only be 0 or 1 */ 609 if (msgseq > 2) { 610 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER); 611 goto end; 612 } 613 614 /* 615 * We don't support fragment reassembly for ClientHellos whilst 616 * listening because that would require server side state (which is 617 * against the whole point of the ClientHello/HelloVerifyRequest 618 * mechanism). Instead we only look at the first ClientHello fragment 619 * and require that the cookie must be contained within it. 620 */ 621 if (fragoff != 0 || fraglen > msglen) { 622 /* Non initial ClientHello fragment (or bad fragment) */ 623 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO); 624 goto end; 625 } 626 627 if (s->msg_callback) 628 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data, 629 fraglen + DTLS1_HM_HEADER_LENGTH, s, 630 s->msg_callback_arg); 631 632 if (!PACKET_get_net_2(&msgpayload, &clientvers)) { 633 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 634 goto end; 635 } 636 637 /* 638 * Verify client version is supported 639 */ 640 if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) && 641 s->method->version != DTLS_ANY_VERSION) { 642 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER); 643 goto end; 644 } 645 646 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE) 647 || !PACKET_get_length_prefixed_1(&msgpayload, &session) 648 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) { 649 /* 650 * Could be malformed or the cookie does not fit within the initial 651 * ClientHello fragment. Either way we can't handle it. 652 */ 653 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH); 654 goto end; 655 } 656 657 /* 658 * Check if we have a cookie or not. If not we need to send a 659 * HelloVerifyRequest. 660 */ 661 if (PACKET_remaining(&cookiepkt) == 0) { 662 next = LISTEN_SEND_VERIFY_REQUEST; 663 } else { 664 /* 665 * We have a cookie, so lets check it. 666 */ 667 if (s->ctx->app_verify_cookie_cb == NULL) { 668 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK); 669 /* This is fatal */ 670 return -1; 671 } 672 if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt), 673 (unsigned int)PACKET_remaining(&cookiepkt)) == 0) { 674 /* 675 * We treat invalid cookies in the same was as no cookie as 676 * per RFC6347 677 */ 678 next = LISTEN_SEND_VERIFY_REQUEST; 679 } else { 680 /* Cookie verification succeeded */ 681 next = LISTEN_SUCCESS; 682 } 683 } 684 685 if (next == LISTEN_SEND_VERIFY_REQUEST) { 686 WPACKET wpkt; 687 unsigned int version; 688 size_t wreclen; 689 690 /* 691 * There was no cookie in the ClientHello so we need to send a 692 * HelloVerifyRequest. If this fails we do not worry about trying 693 * to resend, we just drop it. 694 */ 695 696 /* Generate the cookie */ 697 if (s->ctx->app_gen_cookie_cb == NULL || 698 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 || 699 cookielen > 255) { 700 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE); 701 /* This is fatal */ 702 return -1; 703 } 704 705 /* 706 * Special case: for hello verify request, client version 1.0 and we 707 * haven't decided which version to use yet send back using version 708 * 1.0 header: otherwise some clients will ignore it. 709 */ 710 version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION 711 : s->version; 712 713 /* Construct the record and message headers */ 714 if (!WPACKET_init_static_len(&wpkt, 715 wbuf, 716 ssl_get_max_send_fragment(s) 717 + DTLS1_RT_HEADER_LENGTH, 718 0) 719 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE) 720 || !WPACKET_put_bytes_u16(&wpkt, version) 721 /* 722 * Record sequence number is always the same as in the 723 * received ClientHello 724 */ 725 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE) 726 /* End of record, start sub packet for message */ 727 || !WPACKET_start_sub_packet_u16(&wpkt) 728 /* Message type */ 729 || !WPACKET_put_bytes_u8(&wpkt, 730 DTLS1_MT_HELLO_VERIFY_REQUEST) 731 /* 732 * Message length - doesn't follow normal TLS convention: 733 * the length isn't the last thing in the message header. 734 * We'll need to fill this in later when we know the 735 * length. Set it to zero for now 736 */ 737 || !WPACKET_put_bytes_u24(&wpkt, 0) 738 /* 739 * Message sequence number is always 0 for a 740 * HelloVerifyRequest 741 */ 742 || !WPACKET_put_bytes_u16(&wpkt, 0) 743 /* 744 * We never fragment a HelloVerifyRequest, so fragment 745 * offset is 0 746 */ 747 || !WPACKET_put_bytes_u24(&wpkt, 0) 748 /* 749 * Fragment length is the same as message length, but 750 * this *is* the last thing in the message header so we 751 * can just start a sub-packet. No need to come back 752 * later for this one. 753 */ 754 || !WPACKET_start_sub_packet_u24(&wpkt) 755 /* Create the actual HelloVerifyRequest body */ 756 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen) 757 /* Close message body */ 758 || !WPACKET_close(&wpkt) 759 /* Close record body */ 760 || !WPACKET_close(&wpkt) 761 || !WPACKET_get_total_written(&wpkt, &wreclen) 762 || !WPACKET_finish(&wpkt)) { 763 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR); 764 WPACKET_cleanup(&wpkt); 765 /* This is fatal */ 766 return -1; 767 } 768 769 /* 770 * Fix up the message len in the message header. Its the same as the 771 * fragment len which has been filled in by WPACKET, so just copy 772 * that. Destination for the message len is after the record header 773 * plus one byte for the message content type. The source is the 774 * last 3 bytes of the message header 775 */ 776 memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1], 777 &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3], 778 3); 779 780 if (s->msg_callback) 781 s->msg_callback(1, 0, SSL3_RT_HEADER, buf, 782 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 783 784 if ((tmpclient = BIO_ADDR_new()) == NULL) { 785 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE); 786 goto end; 787 } 788 789 /* 790 * This is unnecessary if rbio and wbio are one and the same - but 791 * maybe they're not. We ignore errors here - some BIOs do not 792 * support this. 793 */ 794 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) { 795 (void)BIO_dgram_set_peer(wbio, tmpclient); 796 } 797 BIO_ADDR_free(tmpclient); 798 tmpclient = NULL; 799 800 /* TODO(size_t): convert this call */ 801 if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) { 802 if (BIO_should_retry(wbio)) { 803 /* 804 * Non-blocking IO...but we're stateless, so we're just 805 * going to drop this packet. 806 */ 807 goto end; 808 } 809 return -1; 810 } 811 812 if (BIO_flush(wbio) <= 0) { 813 if (BIO_should_retry(wbio)) { 814 /* 815 * Non-blocking IO...but we're stateless, so we're just 816 * going to drop this packet. 817 */ 818 goto end; 819 } 820 return -1; 821 } 822 } 823 } while (next != LISTEN_SUCCESS); 824 825 /* 826 * Set expected sequence numbers to continue the handshake. 827 */ 828 s->d1->handshake_read_seq = 1; 829 s->d1->handshake_write_seq = 1; 830 s->d1->next_handshake_write_seq = 1; 831 DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq); 832 833 /* 834 * We are doing cookie exchange, so make sure we set that option in the 835 * SSL object 836 */ 837 SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE); 838 839 /* 840 * Tell the state machine that we've done the initial hello verify 841 * exchange 842 */ 843 ossl_statem_set_hello_verify_done(s); 844 845 /* 846 * Some BIOs may not support this. If we fail we clear the client address 847 */ 848 if (BIO_dgram_get_peer(rbio, client) <= 0) 849 BIO_ADDR_clear(client); 850 851 /* Buffer the record in the processed_rcds queue */ 852 if (!dtls_buffer_listen_record(s, reclen, seq, align)) 853 return -1; 854 855 ret = 1; 856 end: 857 BIO_ADDR_free(tmpclient); 858 return ret; 859 } 860 #endif 861 862 static int dtls1_handshake_write(SSL *s) 863 { 864 return dtls1_do_write(s, SSL3_RT_HANDSHAKE); 865 } 866 867 int dtls1_shutdown(SSL *s) 868 { 869 int ret; 870 #ifndef OPENSSL_NO_SCTP 871 BIO *wbio; 872 873 wbio = SSL_get_wbio(s); 874 if (wbio != NULL && BIO_dgram_is_sctp(wbio) && 875 !(s->shutdown & SSL_SENT_SHUTDOWN)) { 876 ret = BIO_dgram_sctp_wait_for_dry(wbio); 877 if (ret < 0) 878 return -1; 879 880 if (ret == 0) 881 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1, 882 NULL); 883 } 884 #endif 885 ret = ssl3_shutdown(s); 886 #ifndef OPENSSL_NO_SCTP 887 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL); 888 #endif 889 return ret; 890 } 891 892 int dtls1_query_mtu(SSL *s) 893 { 894 if (s->d1->link_mtu) { 895 s->d1->mtu = 896 s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 897 s->d1->link_mtu = 0; 898 } 899 900 /* AHA! Figure out the MTU, and stick to the right size */ 901 if (s->d1->mtu < dtls1_min_mtu(s)) { 902 if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 903 s->d1->mtu = 904 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 905 906 /* 907 * I've seen the kernel return bogus numbers when it doesn't know 908 * (initial write), so just make sure we have a reasonable number 909 */ 910 if (s->d1->mtu < dtls1_min_mtu(s)) { 911 /* Set to min mtu */ 912 s->d1->mtu = dtls1_min_mtu(s); 913 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU, 914 (long)s->d1->mtu, NULL); 915 } 916 } else 917 return 0; 918 } 919 return 1; 920 } 921 922 static size_t dtls1_link_min_mtu(void) 923 { 924 return (g_probable_mtu[(sizeof(g_probable_mtu) / 925 sizeof(g_probable_mtu[0])) - 1]); 926 } 927 928 size_t dtls1_min_mtu(SSL *s) 929 { 930 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 931 } 932 933 size_t DTLS_get_data_mtu(const SSL *s) 934 { 935 size_t mac_overhead, int_overhead, blocksize, ext_overhead; 936 const SSL_CIPHER *ciph = SSL_get_current_cipher(s); 937 size_t mtu = s->d1->mtu; 938 939 if (ciph == NULL) 940 return 0; 941 942 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead, 943 &blocksize, &ext_overhead)) 944 return 0; 945 946 if (SSL_READ_ETM(s)) 947 ext_overhead += mac_overhead; 948 else 949 int_overhead += mac_overhead; 950 951 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */ 952 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu) 953 return 0; 954 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH; 955 956 /* Round encrypted payload down to cipher block size (for CBC etc.) 957 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */ 958 if (blocksize) 959 mtu -= (mtu % blocksize); 960 961 /* Subtract internal overhead (e.g. CBC padding len byte) */ 962 if (int_overhead >= mtu) 963 return 0; 964 mtu -= int_overhead; 965 966 return mtu; 967 } 968 969 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb) 970 { 971 s->d1->timer_cb = cb; 972 } 973