1 /* 2 * Copyright 2005-2026 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include "internal/e_os.h" 11 #include "internal/e_winsock.h" /* struct timeval for DTLS_CTRL_GET_TIMEOUT */ 12 #include <stdio.h> 13 #include <openssl/objects.h> 14 #include <openssl/rand.h> 15 #include "ssl_local.h" 16 #include "internal/time.h" 17 #include "internal/ssl_unwrap.h" 18 19 static int dtls1_handshake_write(SSL_CONNECTION *s); 20 static size_t dtls1_link_min_mtu(void); 21 22 /* XDTLS: figure out the right values */ 23 static const size_t g_probable_mtu[] = { 1500, 512, 256 }; 24 25 const SSL3_ENC_METHOD DTLSv1_enc_data = { 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, 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_setup_key_block, 42 tls1_generate_master_secret, 43 tls1_change_cipher_state, 44 tls1_final_finish_mac, 45 TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE, 46 TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE, 47 tls1_alert_code, 48 tls1_export_keying_material, 49 SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_SIGALGS 50 | SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS, 51 dtls1_set_handshake_header, 52 dtls1_close_construct_packet, 53 dtls1_handshake_write 54 }; 55 56 OSSL_TIME dtls1_default_timeout(void) 57 { 58 /* 59 * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for 60 * http, the cache would over fill 61 */ 62 return ossl_seconds2time(60 * 60 * 2); 63 } 64 65 int dtls1_new(SSL *ssl) 66 { 67 DTLS1_STATE *d1; 68 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 69 70 if (s == NULL) 71 return 0; 72 73 if (!DTLS_RECORD_LAYER_new(&s->rlayer)) { 74 return 0; 75 } 76 77 if (!ssl3_new(ssl)) 78 return 0; 79 if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) { 80 ssl3_free(ssl); 81 return 0; 82 } 83 84 d1->buffered_messages = pqueue_new(); 85 d1->sent_messages = pqueue_new(); 86 87 if (s->server) { 88 d1->cookie_len = sizeof(s->d1->cookie); 89 } 90 91 d1->link_mtu = 0; 92 d1->mtu = 0; 93 94 if (d1->buffered_messages == NULL || d1->sent_messages == NULL) { 95 pqueue_free(d1->buffered_messages); 96 pqueue_free(d1->sent_messages); 97 OPENSSL_free(d1); 98 ssl3_free(ssl); 99 return 0; 100 } 101 102 s->d1 = d1; 103 104 if (!ssl->method->ssl_clear(ssl)) 105 return 0; 106 107 return 1; 108 } 109 110 static void dtls1_clear_queues(SSL_CONNECTION *s) 111 { 112 dtls1_clear_received_buffer(s); 113 dtls1_clear_sent_buffer(s); 114 } 115 116 void dtls1_clear_received_buffer(SSL_CONNECTION *s) 117 { 118 pitem *item = NULL; 119 hm_fragment *frag = NULL; 120 121 while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) { 122 frag = (hm_fragment *)item->data; 123 dtls1_hm_fragment_free(frag); 124 pitem_free(item); 125 } 126 } 127 128 void dtls1_clear_sent_buffer(SSL_CONNECTION *s) 129 { 130 pitem *item = NULL; 131 hm_fragment *frag = NULL; 132 133 while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) { 134 frag = (hm_fragment *)item->data; 135 136 if (frag->msg_header.is_ccs 137 && frag->msg_header.saved_retransmit_state.wrlmethod != NULL 138 && s->rlayer.wrl != frag->msg_header.saved_retransmit_state.wrl) { 139 /* 140 * If we're freeing the CCS then we're done with the old wrl and it 141 * can bee freed 142 */ 143 frag->msg_header.saved_retransmit_state.wrlmethod->free(frag->msg_header.saved_retransmit_state.wrl); 144 } 145 146 dtls1_hm_fragment_free(frag); 147 pitem_free(item); 148 } 149 } 150 151 void dtls1_free(SSL *ssl) 152 { 153 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 154 155 if (s == NULL) 156 return; 157 158 if (s->d1 != NULL) { 159 dtls1_clear_queues(s); 160 pqueue_free(s->d1->buffered_messages); 161 pqueue_free(s->d1->sent_messages); 162 } 163 164 DTLS_RECORD_LAYER_free(&s->rlayer); 165 166 ssl3_free(ssl); 167 168 OPENSSL_free(s->d1); 169 s->d1 = NULL; 170 } 171 172 int dtls1_clear(SSL *ssl) 173 { 174 pqueue *buffered_messages; 175 pqueue *sent_messages; 176 size_t mtu; 177 size_t link_mtu; 178 179 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 180 181 if (s == NULL) 182 return 0; 183 184 DTLS_RECORD_LAYER_clear(&s->rlayer); 185 186 if (s->d1) { 187 DTLS_timer_cb timer_cb = s->d1->timer_cb; 188 189 buffered_messages = s->d1->buffered_messages; 190 sent_messages = s->d1->sent_messages; 191 mtu = s->d1->mtu; 192 link_mtu = s->d1->link_mtu; 193 194 dtls1_clear_queues(s); 195 196 memset(s->d1, 0, sizeof(*s->d1)); 197 198 /* Restore the timer callback from previous state */ 199 s->d1->timer_cb = timer_cb; 200 201 if (s->server) { 202 s->d1->cookie_len = sizeof(s->d1->cookie); 203 } 204 205 if (SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU) { 206 s->d1->mtu = mtu; 207 s->d1->link_mtu = link_mtu; 208 } 209 210 s->d1->buffered_messages = buffered_messages; 211 s->d1->sent_messages = sent_messages; 212 } 213 214 if (!ssl3_clear(ssl)) 215 return 0; 216 217 if (ssl->method->version == DTLS_ANY_VERSION) 218 s->version = DTLS_MAX_VERSION_INTERNAL; 219 #ifndef OPENSSL_NO_DTLS1_METHOD 220 else if (s->options & SSL_OP_CISCO_ANYCONNECT) 221 s->client_version = s->version = DTLS1_BAD_VER; 222 #endif 223 else 224 s->version = ssl->method->version; 225 226 return 1; 227 } 228 229 long dtls1_ctrl(SSL *ssl, int cmd, long larg, void *parg) 230 { 231 int ret = 0; 232 OSSL_TIME t; 233 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 234 235 if (s == NULL) 236 return 0; 237 238 switch (cmd) { 239 case DTLS_CTRL_GET_TIMEOUT: 240 if (dtls1_get_timeout(s, &t)) { 241 *(struct timeval *)parg = ossl_time_to_timeval(t); 242 ret = 1; 243 } 244 break; 245 case DTLS_CTRL_HANDLE_TIMEOUT: 246 ret = dtls1_handle_timeout(s); 247 break; 248 case DTLS_CTRL_SET_LINK_MTU: 249 if (larg < (long)dtls1_link_min_mtu()) 250 return 0; 251 s->d1->link_mtu = larg; 252 return 1; 253 case DTLS_CTRL_GET_LINK_MIN_MTU: 254 return (long)dtls1_link_min_mtu(); 255 case SSL_CTRL_SET_MTU: 256 /* 257 * We may not have a BIO set yet so can't call dtls1_min_mtu() 258 * We'll have to make do with dtls1_link_min_mtu() and max overhead 259 */ 260 if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD) 261 return 0; 262 s->d1->mtu = larg; 263 return larg; 264 default: 265 ret = ssl3_ctrl(ssl, cmd, larg, parg); 266 break; 267 } 268 return ret; 269 } 270 271 static void dtls1_bio_set_next_timeout(BIO *bio, const DTLS1_STATE *d1) 272 { 273 struct timeval tv = ossl_time_to_timeval(d1->next_timeout); 274 275 BIO_ctrl(bio, BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, &tv); 276 } 277 278 void dtls1_start_timer(SSL_CONNECTION *s) 279 { 280 OSSL_TIME duration; 281 SSL *ssl = SSL_CONNECTION_GET_SSL(s); 282 283 #ifndef OPENSSL_NO_SCTP 284 /* Disable timer for SCTP */ 285 if (BIO_dgram_is_sctp(SSL_get_wbio(ssl))) { 286 s->d1->next_timeout = ossl_time_zero(); 287 return; 288 } 289 #endif 290 291 /* 292 * If timer is not set, initialize duration with 1 second or 293 * a user-specified value if the timer callback is installed. 294 */ 295 if (ossl_time_is_zero(s->d1->next_timeout)) { 296 if (s->d1->timer_cb != NULL) 297 s->d1->timeout_duration_us = s->d1->timer_cb(ssl, 0); 298 else 299 s->d1->timeout_duration_us = 1000000; 300 } 301 302 /* Set timeout to current time plus duration */ 303 duration = ossl_us2time(s->d1->timeout_duration_us); 304 s->d1->next_timeout = ossl_time_add(ossl_time_now(), duration); 305 306 /* set s->d1->next_timeout into ssl->rbio interface */ 307 dtls1_bio_set_next_timeout(SSL_get_rbio(ssl), s->d1); 308 } 309 310 int dtls1_get_timeout(const SSL_CONNECTION *s, OSSL_TIME *timeleft) 311 { 312 OSSL_TIME timenow; 313 314 /* If no timeout is set, just return NULL */ 315 if (ossl_time_is_zero(s->d1->next_timeout)) 316 return 0; 317 318 /* Get current time */ 319 timenow = ossl_time_now(); 320 321 /* 322 * If timer already expired or if remaining time is less than 15 ms, 323 * set it to 0 to prevent issues because of small divergences with 324 * socket timeouts. 325 */ 326 *timeleft = ossl_time_subtract(s->d1->next_timeout, timenow); 327 if (ossl_time_compare(*timeleft, ossl_ms2time(15)) <= 0) 328 *timeleft = ossl_time_zero(); 329 return 1; 330 } 331 332 int dtls1_is_timer_expired(SSL_CONNECTION *s) 333 { 334 OSSL_TIME timeleft; 335 336 /* Get time left until timeout, return false if no timer running */ 337 if (!dtls1_get_timeout(s, &timeleft)) 338 return 0; 339 340 /* Return false if timer is not expired yet */ 341 if (!ossl_time_is_zero(timeleft)) 342 return 0; 343 344 /* Timer expired, so return true */ 345 return 1; 346 } 347 348 static void dtls1_double_timeout(SSL_CONNECTION *s) 349 { 350 s->d1->timeout_duration_us *= 2; 351 if (s->d1->timeout_duration_us > 60000000) 352 s->d1->timeout_duration_us = 60000000; 353 } 354 355 void dtls1_stop_timer(SSL_CONNECTION *s) 356 { 357 /* Reset everything */ 358 s->d1->timeout_num_alerts = 0; 359 s->d1->next_timeout = ossl_time_zero(); 360 s->d1->timeout_duration_us = 1000000; 361 dtls1_bio_set_next_timeout(s->rbio, s->d1); 362 /* Clear retransmission buffer */ 363 dtls1_clear_sent_buffer(s); 364 } 365 366 int dtls1_check_timeout_num(SSL_CONNECTION *s) 367 { 368 size_t mtu; 369 SSL *ssl = SSL_CONNECTION_GET_SSL(s); 370 371 s->d1->timeout_num_alerts++; 372 373 /* Reduce MTU after 2 unsuccessful retransmissions */ 374 if (s->d1->timeout_num_alerts > 2 375 && !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { 376 mtu = BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL); 377 if (mtu < s->d1->mtu) 378 s->d1->mtu = mtu; 379 } 380 381 if (s->d1->timeout_num_alerts > DTLS1_TMO_ALERT_COUNT) { 382 /* fail the connection, enough alerts have been sent */ 383 SSLfatal(s, SSL_AD_NO_ALERT, SSL_R_READ_TIMEOUT_EXPIRED); 384 return -1; 385 } 386 387 return 0; 388 } 389 390 int dtls1_handle_timeout(SSL_CONNECTION *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(SSL_CONNECTION_GET_USER_SSL(s), 399 s->d1->timeout_duration_us); 400 else 401 dtls1_double_timeout(s); 402 403 if (dtls1_check_timeout_num(s) < 0) { 404 /* SSLfatal() already called */ 405 return -1; 406 } 407 408 dtls1_start_timer(s); 409 410 /* 411 * If write_state is anything other than WRITE_STATE_TRANSITION, a write 412 * is still parked mid-flight (WANT_WRITE) from a previous call into the 413 * state machine - the current flight hasn't actually finished going out 414 * yet, so there's nothing valid to retransmit. Retransmitting anyway 415 * would reconstruct an already-sent message from the retransmit queue 416 * into s->init_buf/s->init_off/s->init_num/s->d1->w_msg - the same 417 * fields the parked write is still using - corrupting that write's 418 * state out from under it. Leave it alone and let the next 419 * SSL_read()/SSL_write()/SSL_accept()/SSL_connect() call resume the 420 * parked write normally instead. 421 */ 422 if (s->statem.state == MSG_FLOW_WRITING 423 && s->statem.write_state != WRITE_STATE_TRANSITION) 424 return 0; 425 426 /* Calls SSLfatal() if required */ 427 return dtls1_retransmit_buffered_messages(s); 428 } 429 430 #define LISTEN_SUCCESS 2 431 #define LISTEN_SEND_VERIFY_REQUEST 1 432 433 #ifndef OPENSSL_NO_SOCK 434 int DTLSv1_listen(SSL *ssl, BIO_ADDR *client) 435 { 436 int next, n, ret = 0; 437 unsigned char cookie[DTLS1_COOKIE_LENGTH]; 438 unsigned char seq[SEQ_NUM_SIZE]; 439 const unsigned char *data; 440 unsigned char *buf = NULL, *wbuf; 441 size_t fragoff, fraglen, msglen; 442 unsigned int rectype, versmajor, versminor, msgseq, msgtype, clientvers, cookielen; 443 BIO *rbio, *wbio; 444 BIO_ADDR *tmpclient = NULL; 445 PACKET pkt, msgpkt, msgpayload, session, cookiepkt; 446 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 447 448 if (s == NULL) 449 return -1; 450 451 if (s->handshake_func == NULL) { 452 /* Not properly initialized yet */ 453 SSL_set_accept_state(ssl); 454 } 455 456 /* Ensure there is no state left over from a previous invocation */ 457 if (!SSL_clear(ssl)) 458 return -1; 459 460 ERR_clear_error(); 461 462 rbio = SSL_get_rbio(ssl); 463 wbio = SSL_get_wbio(ssl); 464 465 if (!rbio || !wbio) { 466 ERR_raise(ERR_LIB_SSL, SSL_R_BIO_NOT_SET); 467 return -1; 468 } 469 470 /* 471 * Note: This check deliberately excludes DTLS1_BAD_VER because that version 472 * requires the MAC to be calculated *including* the first ClientHello 473 * (without the cookie). Since DTLSv1_listen is stateless that cannot be 474 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via 475 * SSL_accept) 476 */ 477 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) { 478 ERR_raise(ERR_LIB_SSL, SSL_R_UNSUPPORTED_SSL_VERSION); 479 return -1; 480 } 481 482 buf = OPENSSL_malloc(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_PLAIN_LENGTH); 483 if (buf == NULL) 484 return -1; 485 wbuf = OPENSSL_malloc(DTLS1_RT_HEADER_LENGTH + SSL3_RT_MAX_PLAIN_LENGTH); 486 if (wbuf == NULL) { 487 OPENSSL_free(buf); 488 return -1; 489 } 490 491 do { 492 /* Get a packet */ 493 494 clear_sys_error(); 495 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH + DTLS1_RT_HEADER_LENGTH); 496 if (n <= 0) { 497 if (BIO_should_retry(rbio)) { 498 /* Non-blocking IO */ 499 goto end; 500 } 501 ret = -1; 502 goto end; 503 } 504 505 if (!PACKET_buf_init(&pkt, buf, n)) { 506 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR); 507 ret = -1; 508 goto end; 509 } 510 511 /* 512 * Parse the received record. If there are any problems with it we just 513 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is 514 * resilient in the face of invalid records (e.g., invalid formatting, 515 * length, MAC, etc.). In general, invalid records SHOULD be silently 516 * discarded, thus preserving the association; however, an error MAY be 517 * logged for diagnostic purposes." 518 */ 519 520 /* this packet contained a partial record, dump it */ 521 if (n < DTLS1_RT_HEADER_LENGTH) { 522 ERR_raise(ERR_LIB_SSL, SSL_R_RECORD_TOO_SMALL); 523 goto end; 524 } 525 526 /* Get the record header */ 527 if (!PACKET_get_1(&pkt, &rectype) 528 || !PACKET_get_1(&pkt, &versmajor) 529 || !PACKET_get_1(&pkt, &versminor)) { 530 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 531 goto end; 532 } 533 534 if (s->msg_callback) 535 s->msg_callback(0, (versmajor << 8) | versminor, SSL3_RT_HEADER, buf, 536 DTLS1_RT_HEADER_LENGTH, ssl, s->msg_callback_arg); 537 538 if (rectype != SSL3_RT_HANDSHAKE) { 539 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 540 goto end; 541 } 542 543 /* 544 * Check record version number. We only check that the major version is 545 * the same. 546 */ 547 if (versmajor != DTLS1_VERSION_MAJOR) { 548 ERR_raise(ERR_LIB_SSL, SSL_R_BAD_PROTOCOL_VERSION_NUMBER); 549 goto end; 550 } 551 552 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */ 553 if (!PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE) 554 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) { 555 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 556 goto end; 557 } 558 /* 559 * We allow data remaining at the end of the packet because there could 560 * be a second record (but we ignore it) 561 */ 562 563 /* This is an initial ClientHello so the epoch has to be 0 */ 564 if (seq[0] != 0 || seq[1] != 0) { 565 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 566 goto end; 567 } 568 569 /* Get a pointer to the raw message for the later callback */ 570 data = PACKET_data(&msgpkt); 571 572 /* Finished processing the record header, now process the message */ 573 if (!PACKET_get_1(&msgpkt, &msgtype) 574 || !PACKET_get_net_3_len(&msgpkt, &msglen) 575 || !PACKET_get_net_2(&msgpkt, &msgseq) 576 || !PACKET_get_net_3_len(&msgpkt, &fragoff) 577 || !PACKET_get_net_3_len(&msgpkt, &fraglen) 578 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen) 579 || PACKET_remaining(&msgpkt) != 0) { 580 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 581 goto end; 582 } 583 584 if (msgtype != SSL3_MT_CLIENT_HELLO) { 585 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 586 goto end; 587 } 588 589 /* Message sequence number can only be 0 or 1 */ 590 if (msgseq > 1) { 591 ERR_raise(ERR_LIB_SSL, SSL_R_INVALID_SEQUENCE_NUMBER); 592 goto end; 593 } 594 595 /* 596 * We don't support fragment reassembly for ClientHellos whilst 597 * listening because that would require server side state (which is 598 * against the whole point of the ClientHello/HelloVerifyRequest 599 * mechanism). Instead we only look at the first ClientHello fragment 600 * and require that the cookie must be contained within it. 601 */ 602 if (fragoff != 0 || fraglen > msglen) { 603 /* Non initial ClientHello fragment (or bad fragment) */ 604 ERR_raise(ERR_LIB_SSL, SSL_R_FRAGMENTED_CLIENT_HELLO); 605 goto end; 606 } 607 608 if (s->msg_callback) 609 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data, 610 fraglen + DTLS1_HM_HEADER_LENGTH, ssl, 611 s->msg_callback_arg); 612 613 if (!PACKET_get_net_2(&msgpayload, &clientvers)) { 614 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 615 goto end; 616 } 617 618 /* 619 * Verify client version is supported 620 */ 621 if (DTLS_VERSION_LT(clientvers, (unsigned int)ssl->method->version) && ssl->method->version != DTLS_ANY_VERSION) { 622 ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_VERSION_NUMBER); 623 goto end; 624 } 625 626 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE) 627 || !PACKET_get_length_prefixed_1(&msgpayload, &session) 628 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) { 629 /* 630 * Could be malformed or the cookie does not fit within the initial 631 * ClientHello fragment. Either way we can't handle it. 632 */ 633 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 634 goto end; 635 } 636 637 /* 638 * Check if we have a cookie or not. If not we need to send a 639 * HelloVerifyRequest. 640 */ 641 if (PACKET_remaining(&cookiepkt) == 0) { 642 next = LISTEN_SEND_VERIFY_REQUEST; 643 } else { 644 /* 645 * We have a cookie, so lets check it. 646 */ 647 if (ssl->ctx->app_verify_cookie_cb == NULL) { 648 ERR_raise(ERR_LIB_SSL, SSL_R_NO_VERIFY_COOKIE_CALLBACK); 649 /* This is fatal */ 650 ret = -1; 651 goto end; 652 } 653 if (ssl->ctx->app_verify_cookie_cb(ssl, PACKET_data(&cookiepkt), 654 (unsigned int)PACKET_remaining(&cookiepkt)) 655 == 0) { 656 /* 657 * We treat invalid cookies in the same was as no cookie as 658 * per RFC6347 659 */ 660 next = LISTEN_SEND_VERIFY_REQUEST; 661 } else { 662 /* Cookie verification succeeded */ 663 next = LISTEN_SUCCESS; 664 } 665 } 666 667 if (next == LISTEN_SEND_VERIFY_REQUEST) { 668 WPACKET wpkt; 669 unsigned int version; 670 size_t wreclen; 671 672 /* 673 * There was no cookie in the ClientHello so we need to send a 674 * HelloVerifyRequest. If this fails we do not worry about trying 675 * to resend, we just drop it. 676 */ 677 678 /* Generate the cookie */ 679 if (ssl->ctx->app_gen_cookie_cb == NULL || ssl->ctx->app_gen_cookie_cb(ssl, cookie, &cookielen) == 0 || cookielen > 255) { 680 ERR_raise(ERR_LIB_SSL, SSL_R_COOKIE_GEN_CALLBACK_FAILURE); 681 /* This is fatal */ 682 ret = -1; 683 goto end; 684 } 685 686 /* 687 * Special case: for hello verify request, client version 1.0 and we 688 * haven't decided which version to use yet send back using version 689 * 1.0 header: otherwise some clients will ignore it. 690 */ 691 version = (ssl->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION 692 : s->version; 693 694 /* Construct the record and message headers */ 695 if (!WPACKET_init_static_len(&wpkt, 696 wbuf, 697 ssl_get_max_send_fragment(s) 698 + DTLS1_RT_HEADER_LENGTH, 699 0) 700 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE) 701 || !WPACKET_put_bytes_u16(&wpkt, version) 702 /* 703 * Record sequence number is always the same as in the 704 * received ClientHello 705 */ 706 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE) 707 /* End of record, start sub packet for message */ 708 || !WPACKET_start_sub_packet_u16(&wpkt) 709 /* Message type */ 710 || !WPACKET_put_bytes_u8(&wpkt, 711 DTLS1_MT_HELLO_VERIFY_REQUEST) 712 /* 713 * Message length - doesn't follow normal TLS convention: 714 * the length isn't the last thing in the message header. 715 * We'll need to fill this in later when we know the 716 * length. Set it to zero for now 717 */ 718 || !WPACKET_put_bytes_u24(&wpkt, 0) 719 /* 720 * Message sequence number is always 0 for a 721 * HelloVerifyRequest 722 */ 723 || !WPACKET_put_bytes_u16(&wpkt, 0) 724 /* 725 * We never fragment a HelloVerifyRequest, so fragment 726 * offset is 0 727 */ 728 || !WPACKET_put_bytes_u24(&wpkt, 0) 729 /* 730 * Fragment length is the same as message length, but 731 * this *is* the last thing in the message header so we 732 * can just start a sub-packet. No need to come back 733 * later for this one. 734 */ 735 || !WPACKET_start_sub_packet_u24(&wpkt) 736 /* Create the actual HelloVerifyRequest body */ 737 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen) 738 /* Close message body */ 739 || !WPACKET_close(&wpkt) 740 /* Close record body */ 741 || !WPACKET_close(&wpkt) 742 || !WPACKET_get_total_written(&wpkt, &wreclen) 743 || !WPACKET_finish(&wpkt)) { 744 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR); 745 WPACKET_cleanup(&wpkt); 746 /* This is fatal */ 747 ret = -1; 748 goto end; 749 } 750 751 /* 752 * Fix up the message len in the message header. Its the same as the 753 * fragment len which has been filled in by WPACKET, so just copy 754 * that. Destination for the message len is after the record header 755 * plus one byte for the message content type. The source is the 756 * last 3 bytes of the message header 757 */ 758 memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1], 759 &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3], 760 3); 761 762 if (s->msg_callback) 763 s->msg_callback(1, version, SSL3_RT_HEADER, wbuf, 764 DTLS1_RT_HEADER_LENGTH, ssl, 765 s->msg_callback_arg); 766 767 if ((tmpclient = BIO_ADDR_new()) == NULL) { 768 ERR_raise(ERR_LIB_SSL, ERR_R_BIO_LIB); 769 goto end; 770 } 771 772 /* 773 * This is unnecessary if rbio and wbio are one and the same - but 774 * maybe they're not. We ignore errors here - some BIOs do not 775 * support this. 776 */ 777 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) { 778 (void)BIO_dgram_set_peer(wbio, tmpclient); 779 } 780 BIO_ADDR_free(tmpclient); 781 tmpclient = NULL; 782 783 if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) { 784 if (BIO_should_retry(wbio)) { 785 /* 786 * Non-blocking IO...but we're stateless, so we're just 787 * going to drop this packet. 788 */ 789 goto end; 790 } 791 ret = -1; 792 goto end; 793 } 794 795 if (BIO_flush(wbio) <= 0) { 796 if (BIO_should_retry(wbio)) { 797 /* 798 * Non-blocking IO...but we're stateless, so we're just 799 * going to drop this packet. 800 */ 801 goto end; 802 } 803 ret = -1; 804 goto end; 805 } 806 } 807 } while (next != LISTEN_SUCCESS); 808 809 /* 810 * Set expected sequence numbers to continue the handshake. 811 */ 812 s->d1->handshake_read_seq = 1; 813 s->d1->handshake_write_seq = 1; 814 s->d1->next_handshake_write_seq = 1; 815 s->rlayer.wrlmethod->increment_sequence_ctr(s->rlayer.wrl); 816 817 /* 818 * We are doing cookie exchange, so make sure we set that option in the 819 * SSL object 820 */ 821 SSL_set_options(ssl, SSL_OP_COOKIE_EXCHANGE); 822 823 /* 824 * Tell the state machine that we've done the initial hello verify 825 * exchange 826 */ 827 ossl_statem_set_hello_verify_done(s); 828 829 /* 830 * Some BIOs may not support this. If we fail we clear the client address 831 */ 832 if (BIO_dgram_get_peer(rbio, client) <= 0) 833 BIO_ADDR_clear(client); 834 835 /* Buffer the record for use by the record layer */ 836 if (BIO_write(s->rlayer.rrlnext, buf, n) != n) { 837 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR); 838 ret = -1; 839 goto end; 840 } 841 842 /* 843 * Reset the record layer - but this time we can use the record we just 844 * buffered in s->rlayer.rrlnext 845 */ 846 if (!ssl_set_new_record_layer(s, 847 DTLS_ANY_VERSION, 848 OSSL_RECORD_DIRECTION_READ, 849 OSSL_RECORD_PROTECTION_LEVEL_NONE, NULL, 0, 850 NULL, 0, NULL, 0, NULL, 0, NULL, 0, 851 NID_undef, NULL, NULL, NULL)) { 852 /* SSLfatal already called */ 853 ret = -1; 854 goto end; 855 } 856 857 ret = 1; 858 end: 859 BIO_ADDR_free(tmpclient); 860 OPENSSL_free(buf); 861 OPENSSL_free(wbuf); 862 return ret; 863 } 864 #endif 865 866 static int dtls1_handshake_write(SSL_CONNECTION *s) 867 { 868 return dtls1_do_write(s, SSL3_RT_HANDSHAKE); 869 } 870 871 int dtls1_shutdown(SSL *s) 872 { 873 int ret; 874 #ifndef OPENSSL_NO_SCTP 875 BIO *wbio; 876 SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL_ONLY(s); 877 878 if (sc == NULL) 879 return -1; 880 881 wbio = SSL_get_wbio(s); 882 if (wbio != NULL && BIO_dgram_is_sctp(wbio) && !(sc->shutdown & SSL_SENT_SHUTDOWN)) { 883 ret = BIO_dgram_sctp_wait_for_dry(wbio); 884 if (ret < 0) 885 return -1; 886 887 if (ret == 0) 888 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1, 889 NULL); 890 } 891 #endif 892 ret = ssl3_shutdown(s); 893 #ifndef OPENSSL_NO_SCTP 894 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL); 895 #endif 896 return ret; 897 } 898 899 int dtls1_query_mtu(SSL_CONNECTION *s) 900 { 901 SSL *ssl = SSL_CONNECTION_GET_SSL(s); 902 903 if (s->d1->link_mtu) { 904 s->d1->mtu = s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(ssl)); 905 s->d1->link_mtu = 0; 906 } 907 908 /* AHA! Figure out the MTU, and stick to the right size */ 909 if (s->d1->mtu < dtls1_min_mtu(s)) { 910 if (!(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { 911 s->d1->mtu = BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 912 913 /* 914 * I've seen the kernel return bogus numbers when it doesn't know 915 * (initial write), so just make sure we have a reasonable number 916 */ 917 if (s->d1->mtu < dtls1_min_mtu(s)) { 918 /* Set to min mtu */ 919 s->d1->mtu = dtls1_min_mtu(s); 920 BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_SET_MTU, 921 (long)s->d1->mtu, NULL); 922 } 923 } else 924 return 0; 925 } 926 return 1; 927 } 928 929 static size_t dtls1_link_min_mtu(void) 930 { 931 return (g_probable_mtu[(sizeof(g_probable_mtu) / sizeof(g_probable_mtu[0])) - 1]); 932 } 933 934 size_t dtls1_min_mtu(SSL_CONNECTION *s) 935 { 936 SSL *ssl = SSL_CONNECTION_GET_SSL(s); 937 938 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(ssl)); 939 } 940 941 size_t DTLS_get_data_mtu(const SSL *ssl) 942 { 943 size_t mac_overhead, int_overhead, blocksize, ext_overhead; 944 const SSL_CIPHER *ciph = SSL_get_current_cipher(ssl); 945 size_t mtu; 946 const SSL_CONNECTION *s = SSL_CONNECTION_FROM_CONST_SSL_ONLY(ssl); 947 948 if (s == NULL) 949 return 0; 950 951 mtu = s->d1->mtu; 952 953 if (ciph == NULL) 954 return 0; 955 956 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead, 957 &blocksize, &ext_overhead)) 958 return 0; 959 960 if (SSL_READ_ETM(s)) 961 ext_overhead += mac_overhead; 962 else 963 int_overhead += mac_overhead; 964 965 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */ 966 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu) 967 return 0; 968 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH; 969 970 /* Round encrypted payload down to cipher block size (for CBC etc.) 971 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */ 972 if (blocksize) 973 mtu -= (mtu % blocksize); 974 975 /* Subtract internal overhead (e.g. CBC padding len byte) */ 976 if (int_overhead >= mtu) 977 return 0; 978 mtu -= int_overhead; 979 980 return mtu; 981 } 982 983 void DTLS_set_timer_cb(SSL *ssl, DTLS_timer_cb cb) 984 { 985 SSL_CONNECTION *s = SSL_CONNECTION_FROM_SSL_ONLY(ssl); 986 987 if (s == NULL) 988 return; 989 990 s->d1->timer_cb = cb; 991 } 992