1 /* 2 * Copyright 2005-2021 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 "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; 133 134 if (frag->msg_header.is_ccs) { 135 /* 136 * If we're freeing the CCS then we're done with the old 137 * enc_write_ctx/write_hash and they can be freed 138 */ 139 if (s->enc_write_ctx 140 != frag->msg_header.saved_retransmit_state.enc_write_ctx) 141 EVP_CIPHER_CTX_free(frag->msg_header.saved_retransmit_state 142 .enc_write_ctx); 143 144 if (s->write_hash 145 != frag->msg_header.saved_retransmit_state.write_hash) 146 EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state 147 .write_hash); 148 } 149 150 dtls1_hm_fragment_free(frag); 151 pitem_free(item); 152 } 153 } 154 155 156 void dtls1_free(SSL *s) 157 { 158 DTLS_RECORD_LAYER_free(&s->rlayer); 159 160 ssl3_free(s); 161 162 if (s->d1 != NULL) { 163 dtls1_clear_queues(s); 164 pqueue_free(s->d1->buffered_messages); 165 pqueue_free(s->d1->sent_messages); 166 } 167 168 OPENSSL_free(s->d1); 169 s->d1 = NULL; 170 } 171 172 int dtls1_clear(SSL *s) 173 { 174 pqueue *buffered_messages; 175 pqueue *sent_messages; 176 size_t mtu; 177 size_t link_mtu; 178 179 DTLS_RECORD_LAYER_clear(&s->rlayer); 180 181 if (s->d1) { 182 DTLS_timer_cb timer_cb = s->d1->timer_cb; 183 184 buffered_messages = s->d1->buffered_messages; 185 sent_messages = s->d1->sent_messages; 186 mtu = s->d1->mtu; 187 link_mtu = s->d1->link_mtu; 188 189 dtls1_clear_queues(s); 190 191 memset(s->d1, 0, sizeof(*s->d1)); 192 193 /* Restore the timer callback from previous state */ 194 s->d1->timer_cb = timer_cb; 195 196 if (s->server) { 197 s->d1->cookie_len = sizeof(s->d1->cookie); 198 } 199 200 if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) { 201 s->d1->mtu = mtu; 202 s->d1->link_mtu = link_mtu; 203 } 204 205 s->d1->buffered_messages = buffered_messages; 206 s->d1->sent_messages = sent_messages; 207 } 208 209 if (!ssl3_clear(s)) 210 return 0; 211 212 if (s->method->version == DTLS_ANY_VERSION) 213 s->version = DTLS_MAX_VERSION_INTERNAL; 214 #ifndef OPENSSL_NO_DTLS1_METHOD 215 else if (s->options & SSL_OP_CISCO_ANYCONNECT) 216 s->client_version = s->version = DTLS1_BAD_VER; 217 #endif 218 else 219 s->version = s->method->version; 220 221 return 1; 222 } 223 224 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg) 225 { 226 int ret = 0; 227 228 switch (cmd) { 229 case DTLS_CTRL_GET_TIMEOUT: 230 if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) { 231 ret = 1; 232 } 233 break; 234 case DTLS_CTRL_HANDLE_TIMEOUT: 235 ret = dtls1_handle_timeout(s); 236 break; 237 case DTLS_CTRL_SET_LINK_MTU: 238 if (larg < (long)dtls1_link_min_mtu()) 239 return 0; 240 s->d1->link_mtu = larg; 241 return 1; 242 case DTLS_CTRL_GET_LINK_MIN_MTU: 243 return (long)dtls1_link_min_mtu(); 244 case SSL_CTRL_SET_MTU: 245 /* 246 * We may not have a BIO set yet so can't call dtls1_min_mtu() 247 * We'll have to make do with dtls1_link_min_mtu() and max overhead 248 */ 249 if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD) 250 return 0; 251 s->d1->mtu = larg; 252 return larg; 253 default: 254 ret = ssl3_ctrl(s, cmd, larg, parg); 255 break; 256 } 257 return ret; 258 } 259 260 void dtls1_start_timer(SSL *s) 261 { 262 unsigned int sec, usec; 263 264 #ifndef OPENSSL_NO_SCTP 265 /* Disable timer for SCTP */ 266 if (BIO_dgram_is_sctp(SSL_get_wbio(s))) { 267 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout)); 268 return; 269 } 270 #endif 271 272 /* 273 * If timer is not set, initialize duration with 1 second or 274 * a user-specified value if the timer callback is installed. 275 */ 276 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) { 277 278 if (s->d1->timer_cb != NULL) 279 s->d1->timeout_duration_us = s->d1->timer_cb(s, 0); 280 else 281 s->d1->timeout_duration_us = 1000000; 282 } 283 284 /* Set timeout to current time */ 285 get_current_time(&(s->d1->next_timeout)); 286 287 /* Add duration to current time */ 288 289 sec = s->d1->timeout_duration_us / 1000000; 290 usec = s->d1->timeout_duration_us - (sec * 1000000); 291 292 s->d1->next_timeout.tv_sec += sec; 293 s->d1->next_timeout.tv_usec += usec; 294 295 if (s->d1->next_timeout.tv_usec >= 1000000) { 296 s->d1->next_timeout.tv_sec++; 297 s->d1->next_timeout.tv_usec -= 1000000; 298 } 299 300 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 301 &(s->d1->next_timeout)); 302 } 303 304 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft) 305 { 306 struct timeval timenow; 307 308 /* If no timeout is set, just return NULL */ 309 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) { 310 return NULL; 311 } 312 313 /* Get current time */ 314 get_current_time(&timenow); 315 316 /* If timer already expired, set remaining time to 0 */ 317 if (s->d1->next_timeout.tv_sec < timenow.tv_sec || 318 (s->d1->next_timeout.tv_sec == timenow.tv_sec && 319 s->d1->next_timeout.tv_usec <= timenow.tv_usec)) { 320 memset(timeleft, 0, sizeof(*timeleft)); 321 return timeleft; 322 } 323 324 /* Calculate time left until timer expires */ 325 memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval)); 326 timeleft->tv_sec -= timenow.tv_sec; 327 timeleft->tv_usec -= timenow.tv_usec; 328 if (timeleft->tv_usec < 0) { 329 timeleft->tv_sec--; 330 timeleft->tv_usec += 1000000; 331 } 332 333 /* 334 * If remaining time is less than 15 ms, set it to 0 to prevent issues 335 * because of small divergences with socket timeouts. 336 */ 337 if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) { 338 memset(timeleft, 0, sizeof(*timeleft)); 339 } 340 341 return timeleft; 342 } 343 344 int dtls1_is_timer_expired(SSL *s) 345 { 346 struct timeval timeleft; 347 348 /* Get time left until timeout, return false if no timer running */ 349 if (dtls1_get_timeout(s, &timeleft) == NULL) { 350 return 0; 351 } 352 353 /* Return false if timer is not expired yet */ 354 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) { 355 return 0; 356 } 357 358 /* Timer expired, so return true */ 359 return 1; 360 } 361 362 static void dtls1_double_timeout(SSL *s) 363 { 364 s->d1->timeout_duration_us *= 2; 365 if (s->d1->timeout_duration_us > 60000000) 366 s->d1->timeout_duration_us = 60000000; 367 } 368 369 void dtls1_stop_timer(SSL *s) 370 { 371 /* Reset everything */ 372 s->d1->timeout_num_alerts = 0; 373 memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout)); 374 s->d1->timeout_duration_us = 1000000; 375 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 376 &(s->d1->next_timeout)); 377 /* Clear retransmission buffer */ 378 dtls1_clear_sent_buffer(s); 379 } 380 381 int dtls1_check_timeout_num(SSL *s) 382 { 383 size_t mtu; 384 385 s->d1->timeout_num_alerts++; 386 387 /* Reduce MTU after 2 unsuccessful retransmissions */ 388 if (s->d1->timeout_num_alerts > 2 389 && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 390 mtu = 391 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL); 392 if (mtu < s->d1->mtu) 393 s->d1->mtu = mtu; 394 } 395 396 if (s->d1->timeout_num_alerts > DTLS1_TMO_ALERT_COUNT) { 397 /* fail the connection, enough alerts have been sent */ 398 SSLfatal(s, SSL_AD_NO_ALERT, SSL_R_READ_TIMEOUT_EXPIRED); 399 return -1; 400 } 401 402 return 0; 403 } 404 405 int dtls1_handle_timeout(SSL *s) 406 { 407 /* if no timer is expired, don't do anything */ 408 if (!dtls1_is_timer_expired(s)) { 409 return 0; 410 } 411 412 if (s->d1->timer_cb != NULL) 413 s->d1->timeout_duration_us = s->d1->timer_cb(s, s->d1->timeout_duration_us); 414 else 415 dtls1_double_timeout(s); 416 417 if (dtls1_check_timeout_num(s) < 0) { 418 /* SSLfatal() already called */ 419 return -1; 420 } 421 422 dtls1_start_timer(s); 423 /* Calls SSLfatal() if required */ 424 return dtls1_retransmit_buffered_messages(s); 425 } 426 427 static void get_current_time(struct timeval *t) 428 { 429 #if defined(_WIN32) 430 SYSTEMTIME st; 431 union { 432 unsigned __int64 ul; 433 FILETIME ft; 434 } now; 435 436 GetSystemTime(&st); 437 SystemTimeToFileTime(&st, &now.ft); 438 /* re-bias to 1/1/1970 */ 439 # ifdef __MINGW32__ 440 now.ul -= 116444736000000000ULL; 441 # else 442 /* *INDENT-OFF* */ 443 now.ul -= 116444736000000000UI64; 444 /* *INDENT-ON* */ 445 # endif 446 t->tv_sec = (long)(now.ul / 10000000); 447 t->tv_usec = ((int)(now.ul % 10000000)) / 10; 448 #else 449 gettimeofday(t, NULL); 450 #endif 451 } 452 453 #define LISTEN_SUCCESS 2 454 #define LISTEN_SEND_VERIFY_REQUEST 1 455 456 #ifndef OPENSSL_NO_SOCK 457 int DTLSv1_listen(SSL *s, BIO_ADDR *client) 458 { 459 int next, n, ret = 0; 460 unsigned char cookie[DTLS1_COOKIE_LENGTH]; 461 unsigned char seq[SEQ_NUM_SIZE]; 462 const unsigned char *data; 463 unsigned char *buf, *wbuf; 464 size_t fragoff, fraglen, msglen, reclen, align = 0; 465 unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen; 466 BIO *rbio, *wbio; 467 BIO_ADDR *tmpclient = NULL; 468 PACKET pkt, msgpkt, msgpayload, session, cookiepkt; 469 470 if (s->handshake_func == NULL) { 471 /* Not properly initialized yet */ 472 SSL_set_accept_state(s); 473 } 474 475 /* Ensure there is no state left over from a previous invocation */ 476 if (!SSL_clear(s)) 477 return -1; 478 479 ERR_clear_error(); 480 481 rbio = SSL_get_rbio(s); 482 wbio = SSL_get_wbio(s); 483 484 if (!rbio || !wbio) { 485 ERR_raise(ERR_LIB_SSL, SSL_R_BIO_NOT_SET); 486 return -1; 487 } 488 489 /* 490 * Note: This check deliberately excludes DTLS1_BAD_VER because that version 491 * requires the MAC to be calculated *including* the first ClientHello 492 * (without the cookie). Since DTLSv1_listen is stateless that cannot be 493 * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via 494 * SSL_accept) 495 */ 496 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) { 497 ERR_raise(ERR_LIB_SSL, SSL_R_UNSUPPORTED_SSL_VERSION); 498 return -1; 499 } 500 501 if (!ssl3_setup_buffers(s)) { 502 /* ERR_raise() already called */ 503 return -1; 504 } 505 buf = RECORD_LAYER_get_rbuf(&s->rlayer)->buf; 506 wbuf = RECORD_LAYER_get_wbuf(&s->rlayer)[0].buf; 507 #if defined(SSL3_ALIGN_PAYLOAD) 508 # if SSL3_ALIGN_PAYLOAD != 0 509 /* 510 * Using SSL3_RT_HEADER_LENGTH here instead of DTLS1_RT_HEADER_LENGTH for 511 * consistency with ssl3_read_n. In practice it should make no difference 512 * for sensible values of SSL3_ALIGN_PAYLOAD because the difference between 513 * SSL3_RT_HEADER_LENGTH and DTLS1_RT_HEADER_LENGTH is exactly 8 514 */ 515 align = (size_t)buf + SSL3_RT_HEADER_LENGTH; 516 align = SSL3_ALIGN_PAYLOAD - 1 - ((align - 1) % SSL3_ALIGN_PAYLOAD); 517 # endif 518 #endif 519 buf += align; 520 521 do { 522 /* Get a packet */ 523 524 clear_sys_error(); 525 n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH 526 + DTLS1_RT_HEADER_LENGTH); 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 (!PACKET_buf_init(&pkt, buf, n)) { 536 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR); 537 return -1; 538 } 539 540 /* 541 * Parse the received record. If there are any problems with it we just 542 * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is 543 * resilient in the face of invalid records (e.g., invalid formatting, 544 * length, MAC, etc.). In general, invalid records SHOULD be silently 545 * discarded, thus preserving the association; however, an error MAY be 546 * logged for diagnostic purposes." 547 */ 548 549 /* this packet contained a partial record, dump it */ 550 if (n < DTLS1_RT_HEADER_LENGTH) { 551 ERR_raise(ERR_LIB_SSL, SSL_R_RECORD_TOO_SMALL); 552 goto end; 553 } 554 555 if (s->msg_callback) 556 s->msg_callback(0, 0, SSL3_RT_HEADER, buf, 557 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 558 559 /* Get the record header */ 560 if (!PACKET_get_1(&pkt, &rectype) 561 || !PACKET_get_1(&pkt, &versmajor)) { 562 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 563 goto end; 564 } 565 566 if (rectype != SSL3_RT_HANDSHAKE) { 567 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 568 goto end; 569 } 570 571 /* 572 * Check record version number. We only check that the major version is 573 * the same. 574 */ 575 if (versmajor != DTLS1_VERSION_MAJOR) { 576 ERR_raise(ERR_LIB_SSL, SSL_R_BAD_PROTOCOL_VERSION_NUMBER); 577 goto end; 578 } 579 580 if (!PACKET_forward(&pkt, 1) 581 /* Save the sequence number: 64 bits, with top 2 bytes = epoch */ 582 || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE) 583 || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) { 584 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 585 goto end; 586 } 587 reclen = PACKET_remaining(&msgpkt); 588 /* 589 * We allow data remaining at the end of the packet because there could 590 * be a second record (but we ignore it) 591 */ 592 593 /* This is an initial ClientHello so the epoch has to be 0 */ 594 if (seq[0] != 0 || seq[1] != 0) { 595 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 596 goto end; 597 } 598 599 /* Get a pointer to the raw message for the later callback */ 600 data = PACKET_data(&msgpkt); 601 602 /* Finished processing the record header, now process the message */ 603 if (!PACKET_get_1(&msgpkt, &msgtype) 604 || !PACKET_get_net_3_len(&msgpkt, &msglen) 605 || !PACKET_get_net_2(&msgpkt, &msgseq) 606 || !PACKET_get_net_3_len(&msgpkt, &fragoff) 607 || !PACKET_get_net_3_len(&msgpkt, &fraglen) 608 || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen) 609 || PACKET_remaining(&msgpkt) != 0) { 610 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 611 goto end; 612 } 613 614 if (msgtype != SSL3_MT_CLIENT_HELLO) { 615 ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE); 616 goto end; 617 } 618 619 /* Message sequence number can only be 0 or 1 */ 620 if (msgseq > 2) { 621 ERR_raise(ERR_LIB_SSL, SSL_R_INVALID_SEQUENCE_NUMBER); 622 goto end; 623 } 624 625 /* 626 * We don't support fragment reassembly for ClientHellos whilst 627 * listening because that would require server side state (which is 628 * against the whole point of the ClientHello/HelloVerifyRequest 629 * mechanism). Instead we only look at the first ClientHello fragment 630 * and require that the cookie must be contained within it. 631 */ 632 if (fragoff != 0 || fraglen > msglen) { 633 /* Non initial ClientHello fragment (or bad fragment) */ 634 ERR_raise(ERR_LIB_SSL, SSL_R_FRAGMENTED_CLIENT_HELLO); 635 goto end; 636 } 637 638 if (s->msg_callback) 639 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data, 640 fraglen + DTLS1_HM_HEADER_LENGTH, s, 641 s->msg_callback_arg); 642 643 if (!PACKET_get_net_2(&msgpayload, &clientvers)) { 644 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 645 goto end; 646 } 647 648 /* 649 * Verify client version is supported 650 */ 651 if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) && 652 s->method->version != DTLS_ANY_VERSION) { 653 ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_VERSION_NUMBER); 654 goto end; 655 } 656 657 if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE) 658 || !PACKET_get_length_prefixed_1(&msgpayload, &session) 659 || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) { 660 /* 661 * Could be malformed or the cookie does not fit within the initial 662 * ClientHello fragment. Either way we can't handle it. 663 */ 664 ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH); 665 goto end; 666 } 667 668 /* 669 * Check if we have a cookie or not. If not we need to send a 670 * HelloVerifyRequest. 671 */ 672 if (PACKET_remaining(&cookiepkt) == 0) { 673 next = LISTEN_SEND_VERIFY_REQUEST; 674 } else { 675 /* 676 * We have a cookie, so lets check it. 677 */ 678 if (s->ctx->app_verify_cookie_cb == NULL) { 679 ERR_raise(ERR_LIB_SSL, SSL_R_NO_VERIFY_COOKIE_CALLBACK); 680 /* This is fatal */ 681 return -1; 682 } 683 if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt), 684 (unsigned int)PACKET_remaining(&cookiepkt)) == 0) { 685 /* 686 * We treat invalid cookies in the same was as no cookie as 687 * per RFC6347 688 */ 689 next = LISTEN_SEND_VERIFY_REQUEST; 690 } else { 691 /* Cookie verification succeeded */ 692 next = LISTEN_SUCCESS; 693 } 694 } 695 696 if (next == LISTEN_SEND_VERIFY_REQUEST) { 697 WPACKET wpkt; 698 unsigned int version; 699 size_t wreclen; 700 701 /* 702 * There was no cookie in the ClientHello so we need to send a 703 * HelloVerifyRequest. If this fails we do not worry about trying 704 * to resend, we just drop it. 705 */ 706 707 /* Generate the cookie */ 708 if (s->ctx->app_gen_cookie_cb == NULL || 709 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 || 710 cookielen > 255) { 711 ERR_raise(ERR_LIB_SSL, SSL_R_COOKIE_GEN_CALLBACK_FAILURE); 712 /* This is fatal */ 713 return -1; 714 } 715 716 /* 717 * Special case: for hello verify request, client version 1.0 and we 718 * haven't decided which version to use yet send back using version 719 * 1.0 header: otherwise some clients will ignore it. 720 */ 721 version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION 722 : s->version; 723 724 /* Construct the record and message headers */ 725 if (!WPACKET_init_static_len(&wpkt, 726 wbuf, 727 ssl_get_max_send_fragment(s) 728 + DTLS1_RT_HEADER_LENGTH, 729 0) 730 || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE) 731 || !WPACKET_put_bytes_u16(&wpkt, version) 732 /* 733 * Record sequence number is always the same as in the 734 * received ClientHello 735 */ 736 || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE) 737 /* End of record, start sub packet for message */ 738 || !WPACKET_start_sub_packet_u16(&wpkt) 739 /* Message type */ 740 || !WPACKET_put_bytes_u8(&wpkt, 741 DTLS1_MT_HELLO_VERIFY_REQUEST) 742 /* 743 * Message length - doesn't follow normal TLS convention: 744 * the length isn't the last thing in the message header. 745 * We'll need to fill this in later when we know the 746 * length. Set it to zero for now 747 */ 748 || !WPACKET_put_bytes_u24(&wpkt, 0) 749 /* 750 * Message sequence number is always 0 for a 751 * HelloVerifyRequest 752 */ 753 || !WPACKET_put_bytes_u16(&wpkt, 0) 754 /* 755 * We never fragment a HelloVerifyRequest, so fragment 756 * offset is 0 757 */ 758 || !WPACKET_put_bytes_u24(&wpkt, 0) 759 /* 760 * Fragment length is the same as message length, but 761 * this *is* the last thing in the message header so we 762 * can just start a sub-packet. No need to come back 763 * later for this one. 764 */ 765 || !WPACKET_start_sub_packet_u24(&wpkt) 766 /* Create the actual HelloVerifyRequest body */ 767 || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen) 768 /* Close message body */ 769 || !WPACKET_close(&wpkt) 770 /* Close record body */ 771 || !WPACKET_close(&wpkt) 772 || !WPACKET_get_total_written(&wpkt, &wreclen) 773 || !WPACKET_finish(&wpkt)) { 774 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR); 775 WPACKET_cleanup(&wpkt); 776 /* This is fatal */ 777 return -1; 778 } 779 780 /* 781 * Fix up the message len in the message header. Its the same as the 782 * fragment len which has been filled in by WPACKET, so just copy 783 * that. Destination for the message len is after the record header 784 * plus one byte for the message content type. The source is the 785 * last 3 bytes of the message header 786 */ 787 memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1], 788 &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3], 789 3); 790 791 if (s->msg_callback) 792 s->msg_callback(1, 0, SSL3_RT_HEADER, buf, 793 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg); 794 795 if ((tmpclient = BIO_ADDR_new()) == NULL) { 796 ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE); 797 goto end; 798 } 799 800 /* 801 * This is unnecessary if rbio and wbio are one and the same - but 802 * maybe they're not. We ignore errors here - some BIOs do not 803 * support this. 804 */ 805 if (BIO_dgram_get_peer(rbio, tmpclient) > 0) { 806 (void)BIO_dgram_set_peer(wbio, tmpclient); 807 } 808 BIO_ADDR_free(tmpclient); 809 tmpclient = NULL; 810 811 if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) { 812 if (BIO_should_retry(wbio)) { 813 /* 814 * Non-blocking IO...but we're stateless, so we're just 815 * going to drop this packet. 816 */ 817 goto end; 818 } 819 return -1; 820 } 821 822 if (BIO_flush(wbio) <= 0) { 823 if (BIO_should_retry(wbio)) { 824 /* 825 * Non-blocking IO...but we're stateless, so we're just 826 * going to drop this packet. 827 */ 828 goto end; 829 } 830 return -1; 831 } 832 } 833 } while (next != LISTEN_SUCCESS); 834 835 /* 836 * Set expected sequence numbers to continue the handshake. 837 */ 838 s->d1->handshake_read_seq = 1; 839 s->d1->handshake_write_seq = 1; 840 s->d1->next_handshake_write_seq = 1; 841 DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq); 842 843 /* 844 * We are doing cookie exchange, so make sure we set that option in the 845 * SSL object 846 */ 847 SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE); 848 849 /* 850 * Tell the state machine that we've done the initial hello verify 851 * exchange 852 */ 853 ossl_statem_set_hello_verify_done(s); 854 855 /* 856 * Some BIOs may not support this. If we fail we clear the client address 857 */ 858 if (BIO_dgram_get_peer(rbio, client) <= 0) 859 BIO_ADDR_clear(client); 860 861 /* Buffer the record in the processed_rcds queue */ 862 if (!dtls_buffer_listen_record(s, reclen, seq, align)) 863 return -1; 864 865 ret = 1; 866 end: 867 BIO_ADDR_free(tmpclient); 868 return ret; 869 } 870 #endif 871 872 static int dtls1_handshake_write(SSL *s) 873 { 874 return dtls1_do_write(s, SSL3_RT_HANDSHAKE); 875 } 876 877 int dtls1_shutdown(SSL *s) 878 { 879 int ret; 880 #ifndef OPENSSL_NO_SCTP 881 BIO *wbio; 882 883 wbio = SSL_get_wbio(s); 884 if (wbio != NULL && BIO_dgram_is_sctp(wbio) && 885 !(s->shutdown & SSL_SENT_SHUTDOWN)) { 886 ret = BIO_dgram_sctp_wait_for_dry(wbio); 887 if (ret < 0) 888 return -1; 889 890 if (ret == 0) 891 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1, 892 NULL); 893 } 894 #endif 895 ret = ssl3_shutdown(s); 896 #ifndef OPENSSL_NO_SCTP 897 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL); 898 #endif 899 return ret; 900 } 901 902 int dtls1_query_mtu(SSL *s) 903 { 904 if (s->d1->link_mtu) { 905 s->d1->mtu = 906 s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 907 s->d1->link_mtu = 0; 908 } 909 910 /* AHA! Figure out the MTU, and stick to the right size */ 911 if (s->d1->mtu < dtls1_min_mtu(s)) { 912 if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 913 s->d1->mtu = 914 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 915 916 /* 917 * I've seen the kernel return bogus numbers when it doesn't know 918 * (initial write), so just make sure we have a reasonable number 919 */ 920 if (s->d1->mtu < dtls1_min_mtu(s)) { 921 /* Set to min mtu */ 922 s->d1->mtu = dtls1_min_mtu(s); 923 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU, 924 (long)s->d1->mtu, NULL); 925 } 926 } else 927 return 0; 928 } 929 return 1; 930 } 931 932 static size_t dtls1_link_min_mtu(void) 933 { 934 return (g_probable_mtu[(sizeof(g_probable_mtu) / 935 sizeof(g_probable_mtu[0])) - 1]); 936 } 937 938 size_t dtls1_min_mtu(SSL *s) 939 { 940 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s)); 941 } 942 943 size_t DTLS_get_data_mtu(const SSL *s) 944 { 945 size_t mac_overhead, int_overhead, blocksize, ext_overhead; 946 const SSL_CIPHER *ciph = SSL_get_current_cipher(s); 947 size_t mtu = s->d1->mtu; 948 949 if (ciph == NULL) 950 return 0; 951 952 if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead, 953 &blocksize, &ext_overhead)) 954 return 0; 955 956 if (SSL_READ_ETM(s)) 957 ext_overhead += mac_overhead; 958 else 959 int_overhead += mac_overhead; 960 961 /* Subtract external overhead (e.g. IV/nonce, separate MAC) */ 962 if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu) 963 return 0; 964 mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH; 965 966 /* Round encrypted payload down to cipher block size (for CBC etc.) 967 * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */ 968 if (blocksize) 969 mtu -= (mtu % blocksize); 970 971 /* Subtract internal overhead (e.g. CBC padding len byte) */ 972 if (int_overhead >= mtu) 973 return 0; 974 mtu -= int_overhead; 975 976 return mtu; 977 } 978 979 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb) 980 { 981 s->d1->timer_cb = cb; 982 } 983