1 /* 2 * DTLS implementation written by Nagendra Modadugu 3 * (nagendra (at) cs.stanford.edu) for the OpenSSL project 2005. 4 */ 5 /* ==================================================================== 6 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this 21 * software must display the following acknowledgment: 22 * "This product includes software developed by the OpenSSL Project 23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 24 * 25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26 * endorse or promote products derived from this software without 27 * prior written permission. For written permission, please contact 28 * openssl-core (at) openssl.org. 29 * 30 * 5. Products derived from this software may not be called "OpenSSL" 31 * nor may "OpenSSL" appear in their names without prior written 32 * permission of the OpenSSL Project. 33 * 34 * 6. Redistributions of any form whatsoever must retain the following 35 * acknowledgment: 36 * "This product includes software developed by the OpenSSL Project 37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 38 * 39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50 * OF THE POSSIBILITY OF SUCH DAMAGE. 51 * ==================================================================== 52 * 53 * This product includes cryptographic software written by Eric Young 54 * (eay (at) cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh (at) cryptsoft.com). 56 * 57 */ 58 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 59 * All rights reserved. 60 * 61 * This package is an SSL implementation written 62 * by Eric Young (eay (at) cryptsoft.com). 63 * The implementation was written so as to conform with Netscapes SSL. 64 * 65 * This library is free for commercial and non-commercial use as long as 66 * the following conditions are aheared to. The following conditions 67 * apply to all code found in this distribution, be it the RC4, RSA, 68 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 69 * included with this distribution is covered by the same copyright terms 70 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 71 * 72 * Copyright remains Eric Young's, and as such any Copyright notices in 73 * the code are not to be removed. 74 * If this package is used in a product, Eric Young should be given attribution 75 * as the author of the parts of the library used. 76 * This can be in the form of a textual message at program startup or 77 * in documentation (online or textual) provided with the package. 78 * 79 * Redistribution and use in source and binary forms, with or without 80 * modification, are permitted provided that the following conditions 81 * are met: 82 * 1. Redistributions of source code must retain the copyright 83 * notice, this list of conditions and the following disclaimer. 84 * 2. Redistributions in binary form must reproduce the above copyright 85 * notice, this list of conditions and the following disclaimer in the 86 * documentation and/or other materials provided with the distribution. 87 * 3. All advertising materials mentioning features or use of this software 88 * must display the following acknowledgement: 89 * "This product includes cryptographic software written by 90 * Eric Young (eay (at) cryptsoft.com)" 91 * The word 'cryptographic' can be left out if the rouines from the library 92 * being used are not cryptographic related :-). 93 * 4. If you include any Windows specific code (or a derivative thereof) from 94 * the apps directory (application code) you must include an acknowledgement: 95 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 96 * 97 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 98 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 99 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 100 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 101 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 102 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 103 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 104 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 105 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 106 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 107 * SUCH DAMAGE. 108 * 109 * The licence and distribution terms for any publically available version or 110 * derivative of this code cannot be changed. i.e. this code cannot simply be 111 * copied and put under another distribution licence 112 * [including the GNU Public Licence.] */ 113 114 #include <openssl/ssl.h> 115 116 #include <assert.h> 117 #include <limits.h> 118 #include <string.h> 119 120 #include <openssl/buf.h> 121 #include <openssl/err.h> 122 #include <openssl/evp.h> 123 #include <openssl/mem.h> 124 #include <openssl/rand.h> 125 126 #include "../crypto/internal.h" 127 #include "internal.h" 128 129 130 BSSL_NAMESPACE_BEGIN 131 132 // TODO(davidben): 28 comes from the size of IP + UDP header. Is this reasonable 133 // for these values? Notably, why is kMinMTU a function of the transport 134 // protocol's overhead rather than, say, what's needed to hold a minimally-sized 135 // handshake fragment plus protocol overhead. 136 137 // kMinMTU is the minimum acceptable MTU value. 138 static const unsigned int kMinMTU = 256 - 28; 139 140 // kDefaultMTU is the default MTU value to use if neither the user nor 141 // the underlying BIO supplies one. 142 static const unsigned int kDefaultMTU = 1500 - 28; 143 144 145 // Receiving handshake messages. 146 147 hm_fragment::~hm_fragment() { 148 OPENSSL_free(data); 149 OPENSSL_free(reassembly); 150 } 151 152 static UniquePtr<hm_fragment> dtls1_hm_fragment_new( 153 const struct hm_header_st *msg_hdr) { 154 ScopedCBB cbb; 155 UniquePtr<hm_fragment> frag = MakeUnique<hm_fragment>(); 156 if (!frag) { 157 return nullptr; 158 } 159 frag->type = msg_hdr->type; 160 frag->seq = msg_hdr->seq; 161 frag->msg_len = msg_hdr->msg_len; 162 163 // Allocate space for the reassembled message and fill in the header. 164 frag->data = 165 (uint8_t *)OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len); 166 if (frag->data == NULL) { 167 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 168 return nullptr; 169 } 170 171 if (!CBB_init_fixed(cbb.get(), frag->data, DTLS1_HM_HEADER_LENGTH) || 172 !CBB_add_u8(cbb.get(), msg_hdr->type) || 173 !CBB_add_u24(cbb.get(), msg_hdr->msg_len) || 174 !CBB_add_u16(cbb.get(), msg_hdr->seq) || 175 !CBB_add_u24(cbb.get(), 0 /* frag_off */) || 176 !CBB_add_u24(cbb.get(), msg_hdr->msg_len) || 177 !CBB_finish(cbb.get(), NULL, NULL)) { 178 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 179 return nullptr; 180 } 181 182 // If the handshake message is empty, |frag->reassembly| is NULL. 183 if (msg_hdr->msg_len > 0) { 184 // Initialize reassembly bitmask. 185 if (msg_hdr->msg_len + 7 < msg_hdr->msg_len) { 186 OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); 187 return nullptr; 188 } 189 size_t bitmask_len = (msg_hdr->msg_len + 7) / 8; 190 frag->reassembly = (uint8_t *)OPENSSL_malloc(bitmask_len); 191 if (frag->reassembly == NULL) { 192 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 193 return nullptr; 194 } 195 OPENSSL_memset(frag->reassembly, 0, bitmask_len); 196 } 197 198 return frag; 199 } 200 201 // bit_range returns a |uint8_t| with bits |start|, inclusive, to |end|, 202 // exclusive, set. 203 static uint8_t bit_range(size_t start, size_t end) { 204 return (uint8_t)(~((1u << start) - 1) & ((1u << end) - 1)); 205 } 206 207 // dtls1_hm_fragment_mark marks bytes |start|, inclusive, to |end|, exclusive, 208 // as received in |frag|. If |frag| becomes complete, it clears 209 // |frag->reassembly|. The range must be within the bounds of |frag|'s message 210 // and |frag->reassembly| must not be NULL. 211 static void dtls1_hm_fragment_mark(hm_fragment *frag, size_t start, 212 size_t end) { 213 size_t msg_len = frag->msg_len; 214 215 if (frag->reassembly == NULL || start > end || end > msg_len) { 216 assert(0); 217 return; 218 } 219 // A zero-length message will never have a pending reassembly. 220 assert(msg_len > 0); 221 222 if (start == end) { 223 return; 224 } 225 226 if ((start >> 3) == (end >> 3)) { 227 frag->reassembly[start >> 3] |= bit_range(start & 7, end & 7); 228 } else { 229 frag->reassembly[start >> 3] |= bit_range(start & 7, 8); 230 for (size_t i = (start >> 3) + 1; i < (end >> 3); i++) { 231 frag->reassembly[i] = 0xff; 232 } 233 if ((end & 7) != 0) { 234 frag->reassembly[end >> 3] |= bit_range(0, end & 7); 235 } 236 } 237 238 // Check if the fragment is complete. 239 for (size_t i = 0; i < (msg_len >> 3); i++) { 240 if (frag->reassembly[i] != 0xff) { 241 return; 242 } 243 } 244 if ((msg_len & 7) != 0 && 245 frag->reassembly[msg_len >> 3] != bit_range(0, msg_len & 7)) { 246 return; 247 } 248 249 OPENSSL_free(frag->reassembly); 250 frag->reassembly = NULL; 251 } 252 253 // dtls1_is_current_message_complete returns whether the current handshake 254 // message is complete. 255 static bool dtls1_is_current_message_complete(const SSL *ssl) { 256 size_t idx = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 257 hm_fragment *frag = ssl->d1->incoming_messages[idx].get(); 258 return frag != NULL && frag->reassembly == NULL; 259 } 260 261 // dtls1_get_incoming_message returns the incoming message corresponding to 262 // |msg_hdr|. If none exists, it creates a new one and inserts it in the 263 // queue. Otherwise, it checks |msg_hdr| is consistent with the existing one. It 264 // returns NULL on failure. The caller does not take ownership of the result. 265 static hm_fragment *dtls1_get_incoming_message( 266 SSL *ssl, uint8_t *out_alert, const struct hm_header_st *msg_hdr) { 267 if (msg_hdr->seq < ssl->d1->handshake_read_seq || 268 msg_hdr->seq - ssl->d1->handshake_read_seq >= SSL_MAX_HANDSHAKE_FLIGHT) { 269 *out_alert = SSL_AD_INTERNAL_ERROR; 270 return NULL; 271 } 272 273 size_t idx = msg_hdr->seq % SSL_MAX_HANDSHAKE_FLIGHT; 274 hm_fragment *frag = ssl->d1->incoming_messages[idx].get(); 275 if (frag != NULL) { 276 assert(frag->seq == msg_hdr->seq); 277 // The new fragment must be compatible with the previous fragments from this 278 // message. 279 if (frag->type != msg_hdr->type || 280 frag->msg_len != msg_hdr->msg_len) { 281 OPENSSL_PUT_ERROR(SSL, SSL_R_FRAGMENT_MISMATCH); 282 *out_alert = SSL_AD_ILLEGAL_PARAMETER; 283 return NULL; 284 } 285 return frag; 286 } 287 288 // This is the first fragment from this message. 289 ssl->d1->incoming_messages[idx] = dtls1_hm_fragment_new(msg_hdr); 290 if (!ssl->d1->incoming_messages[idx]) { 291 *out_alert = SSL_AD_INTERNAL_ERROR; 292 return NULL; 293 } 294 return ssl->d1->incoming_messages[idx].get(); 295 } 296 297 ssl_open_record_t dtls1_open_handshake(SSL *ssl, size_t *out_consumed, 298 uint8_t *out_alert, Span<uint8_t> in) { 299 uint8_t type; 300 Span<uint8_t> record; 301 auto ret = dtls_open_record(ssl, &type, &record, out_consumed, out_alert, in); 302 if (ret != ssl_open_record_success) { 303 return ret; 304 } 305 306 switch (type) { 307 case SSL3_RT_APPLICATION_DATA: 308 // Unencrypted application data records are always illegal. 309 if (ssl->s3->aead_read_ctx->is_null_cipher()) { 310 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 311 *out_alert = SSL_AD_UNEXPECTED_MESSAGE; 312 return ssl_open_record_error; 313 } 314 315 // Out-of-order application data may be received between ChangeCipherSpec 316 // and finished. Discard it. 317 return ssl_open_record_discard; 318 319 case SSL3_RT_CHANGE_CIPHER_SPEC: 320 // We do not support renegotiation, so encrypted ChangeCipherSpec records 321 // are illegal. 322 if (!ssl->s3->aead_read_ctx->is_null_cipher()) { 323 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 324 *out_alert = SSL_AD_UNEXPECTED_MESSAGE; 325 return ssl_open_record_error; 326 } 327 328 if (record.size() != 1u || record[0] != SSL3_MT_CCS) { 329 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_CHANGE_CIPHER_SPEC); 330 *out_alert = SSL_AD_ILLEGAL_PARAMETER; 331 return ssl_open_record_error; 332 } 333 334 // Flag the ChangeCipherSpec for later. 335 ssl->d1->has_change_cipher_spec = true; 336 ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_CHANGE_CIPHER_SPEC, 337 record); 338 return ssl_open_record_success; 339 340 case SSL3_RT_HANDSHAKE: 341 // Break out to main processing. 342 break; 343 344 default: 345 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 346 *out_alert = SSL_AD_UNEXPECTED_MESSAGE; 347 return ssl_open_record_error; 348 } 349 350 CBS cbs; 351 CBS_init(&cbs, record.data(), record.size()); 352 while (CBS_len(&cbs) > 0) { 353 // Read a handshake fragment. 354 struct hm_header_st msg_hdr; 355 CBS body; 356 if (!dtls1_parse_fragment(&cbs, &msg_hdr, &body)) { 357 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD); 358 *out_alert = SSL_AD_DECODE_ERROR; 359 return ssl_open_record_error; 360 } 361 362 const size_t frag_off = msg_hdr.frag_off; 363 const size_t frag_len = msg_hdr.frag_len; 364 const size_t msg_len = msg_hdr.msg_len; 365 if (frag_off > msg_len || frag_off + frag_len < frag_off || 366 frag_off + frag_len > msg_len || 367 msg_len > ssl_max_handshake_message_len(ssl)) { 368 OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE); 369 *out_alert = SSL_AD_ILLEGAL_PARAMETER; 370 return ssl_open_record_error; 371 } 372 373 // The encrypted epoch in DTLS has only one handshake message. 374 if (ssl->d1->r_epoch == 1 && msg_hdr.seq != ssl->d1->handshake_read_seq) { 375 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 376 *out_alert = SSL_AD_UNEXPECTED_MESSAGE; 377 return ssl_open_record_error; 378 } 379 380 if (msg_hdr.seq < ssl->d1->handshake_read_seq || 381 msg_hdr.seq > 382 (unsigned)ssl->d1->handshake_read_seq + SSL_MAX_HANDSHAKE_FLIGHT) { 383 // Ignore fragments from the past, or ones too far in the future. 384 continue; 385 } 386 387 hm_fragment *frag = dtls1_get_incoming_message(ssl, out_alert, &msg_hdr); 388 if (frag == NULL) { 389 return ssl_open_record_error; 390 } 391 assert(frag->msg_len == msg_len); 392 393 if (frag->reassembly == NULL) { 394 // The message is already assembled. 395 continue; 396 } 397 assert(msg_len > 0); 398 399 // Copy the body into the fragment. 400 OPENSSL_memcpy(frag->data + DTLS1_HM_HEADER_LENGTH + frag_off, 401 CBS_data(&body), CBS_len(&body)); 402 dtls1_hm_fragment_mark(frag, frag_off, frag_off + frag_len); 403 } 404 405 return ssl_open_record_success; 406 } 407 408 bool dtls1_get_message(SSL *ssl, SSLMessage *out) { 409 if (!dtls1_is_current_message_complete(ssl)) { 410 return false; 411 } 412 413 size_t idx = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 414 hm_fragment *frag = ssl->d1->incoming_messages[idx].get(); 415 out->type = frag->type; 416 CBS_init(&out->body, frag->data + DTLS1_HM_HEADER_LENGTH, frag->msg_len); 417 CBS_init(&out->raw, frag->data, DTLS1_HM_HEADER_LENGTH + frag->msg_len); 418 out->is_v2_hello = false; 419 if (!ssl->s3->has_message) { 420 ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, out->raw); 421 ssl->s3->has_message = true; 422 } 423 return true; 424 } 425 426 void dtls1_next_message(SSL *ssl) { 427 assert(ssl->s3->has_message); 428 assert(dtls1_is_current_message_complete(ssl)); 429 size_t index = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 430 ssl->d1->incoming_messages[index].reset(); 431 ssl->d1->handshake_read_seq++; 432 ssl->s3->has_message = false; 433 // If we previously sent a flight, mark it as having a reply, so 434 // |on_handshake_complete| can manage post-handshake retransmission. 435 if (ssl->d1->outgoing_messages_complete) { 436 ssl->d1->flight_has_reply = true; 437 } 438 } 439 440 bool dtls_has_unprocessed_handshake_data(const SSL *ssl) { 441 if (ssl->d1->has_change_cipher_spec) { 442 return true; 443 } 444 445 size_t current = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 446 for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) { 447 // Skip the current message. 448 if (ssl->s3->has_message && i == current) { 449 assert(dtls1_is_current_message_complete(ssl)); 450 continue; 451 } 452 if (ssl->d1->incoming_messages[i] != nullptr) { 453 return true; 454 } 455 } 456 return false; 457 } 458 459 bool dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr, 460 CBS *out_body) { 461 OPENSSL_memset(out_hdr, 0x00, sizeof(struct hm_header_st)); 462 463 if (!CBS_get_u8(cbs, &out_hdr->type) || 464 !CBS_get_u24(cbs, &out_hdr->msg_len) || 465 !CBS_get_u16(cbs, &out_hdr->seq) || 466 !CBS_get_u24(cbs, &out_hdr->frag_off) || 467 !CBS_get_u24(cbs, &out_hdr->frag_len) || 468 !CBS_get_bytes(cbs, out_body, out_hdr->frag_len)) { 469 return false; 470 } 471 472 return true; 473 } 474 475 ssl_open_record_t dtls1_open_change_cipher_spec(SSL *ssl, size_t *out_consumed, 476 uint8_t *out_alert, 477 Span<uint8_t> in) { 478 if (!ssl->d1->has_change_cipher_spec) { 479 // dtls1_open_handshake processes both handshake and ChangeCipherSpec. 480 auto ret = dtls1_open_handshake(ssl, out_consumed, out_alert, in); 481 if (ret != ssl_open_record_success) { 482 return ret; 483 } 484 } 485 if (ssl->d1->has_change_cipher_spec) { 486 ssl->d1->has_change_cipher_spec = false; 487 return ssl_open_record_success; 488 } 489 return ssl_open_record_discard; 490 } 491 492 493 // Sending handshake messages. 494 495 void DTLS_OUTGOING_MESSAGE::Clear() { 496 OPENSSL_free(data); 497 data = nullptr; 498 } 499 500 void dtls_clear_outgoing_messages(SSL *ssl) { 501 for (size_t i = 0; i < ssl->d1->outgoing_messages_len; i++) { 502 ssl->d1->outgoing_messages[i].Clear(); 503 } 504 ssl->d1->outgoing_messages_len = 0; 505 ssl->d1->outgoing_written = 0; 506 ssl->d1->outgoing_offset = 0; 507 ssl->d1->outgoing_messages_complete = false; 508 ssl->d1->flight_has_reply = false; 509 } 510 511 bool dtls1_init_message(SSL *ssl, CBB *cbb, CBB *body, uint8_t type) { 512 // Pick a modest size hint to save most of the |realloc| calls. 513 if (!CBB_init(cbb, 64) || 514 !CBB_add_u8(cbb, type) || 515 !CBB_add_u24(cbb, 0 /* length (filled in later) */) || 516 !CBB_add_u16(cbb, ssl->d1->handshake_write_seq) || 517 !CBB_add_u24(cbb, 0 /* offset */) || 518 !CBB_add_u24_length_prefixed(cbb, body)) { 519 return false; 520 } 521 522 return true; 523 } 524 525 bool dtls1_finish_message(SSL *ssl, CBB *cbb, Array<uint8_t> *out_msg) { 526 if (!CBBFinishArray(cbb, out_msg) || 527 out_msg->size() < DTLS1_HM_HEADER_LENGTH) { 528 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 529 return false; 530 } 531 532 // Fix up the header. Copy the fragment length into the total message 533 // length. 534 OPENSSL_memcpy(out_msg->data() + 1, 535 out_msg->data() + DTLS1_HM_HEADER_LENGTH - 3, 3); 536 return true; 537 } 538 539 // ssl_size_t_greater_than_32_bits returns whether |v| exceeds the bounds of a 540 // 32-bit value. The obvious thing doesn't work because, in some 32-bit build 541 // configurations, the compiler warns that the test is always false and breaks 542 // the build. 543 static bool ssl_size_t_greater_than_32_bits(size_t v) { 544 #if defined(OPENSSL_64_BIT) 545 return v > 0xffffffff; 546 #elif defined(OPENSSL_32_BIT) 547 return false; 548 #else 549 #error "Building for neither 32- nor 64-bits." 550 #endif 551 } 552 553 // add_outgoing adds a new handshake message or ChangeCipherSpec to the current 554 // outgoing flight. It returns true on success and false on error. 555 static bool add_outgoing(SSL *ssl, bool is_ccs, Array<uint8_t> data) { 556 if (ssl->d1->outgoing_messages_complete) { 557 // If we've begun writing a new flight, we received the peer flight. Discard 558 // the timer and the our flight. 559 dtls1_stop_timer(ssl); 560 dtls_clear_outgoing_messages(ssl); 561 } 562 563 static_assert(SSL_MAX_HANDSHAKE_FLIGHT < 564 (1 << 8 * sizeof(ssl->d1->outgoing_messages_len)), 565 "outgoing_messages_len is too small"); 566 if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT || 567 ssl_size_t_greater_than_32_bits(data.size())) { 568 assert(false); 569 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 570 return false; 571 } 572 573 if (!is_ccs) { 574 // TODO(svaldez): Move this up a layer to fix abstraction for SSLTranscript 575 // on hs. 576 if (ssl->s3->hs != NULL && 577 !ssl->s3->hs->transcript.Update(data)) { 578 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 579 return false; 580 } 581 ssl->d1->handshake_write_seq++; 582 } 583 584 DTLS_OUTGOING_MESSAGE *msg = 585 &ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len]; 586 size_t len; 587 data.Release(&msg->data, &len); 588 msg->len = len; 589 msg->epoch = ssl->d1->w_epoch; 590 msg->is_ccs = is_ccs; 591 592 ssl->d1->outgoing_messages_len++; 593 return true; 594 } 595 596 bool dtls1_add_message(SSL *ssl, Array<uint8_t> data) { 597 return add_outgoing(ssl, false /* handshake */, std::move(data)); 598 } 599 600 bool dtls1_add_change_cipher_spec(SSL *ssl) { 601 return add_outgoing(ssl, true /* ChangeCipherSpec */, Array<uint8_t>()); 602 } 603 604 // dtls1_update_mtu updates the current MTU from the BIO, ensuring it is above 605 // the minimum. 606 static void dtls1_update_mtu(SSL *ssl) { 607 // TODO(davidben): No consumer implements |BIO_CTRL_DGRAM_SET_MTU| and the 608 // only |BIO_CTRL_DGRAM_QUERY_MTU| implementation could use 609 // |SSL_set_mtu|. Does this need to be so complex? 610 if (ssl->d1->mtu < dtls1_min_mtu() && 611 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { 612 long mtu = BIO_ctrl(ssl->wbio.get(), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 613 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { 614 ssl->d1->mtu = (unsigned)mtu; 615 } else { 616 ssl->d1->mtu = kDefaultMTU; 617 BIO_ctrl(ssl->wbio.get(), BIO_CTRL_DGRAM_SET_MTU, ssl->d1->mtu, NULL); 618 } 619 } 620 621 // The MTU should be above the minimum now. 622 assert(ssl->d1->mtu >= dtls1_min_mtu()); 623 } 624 625 enum seal_result_t { 626 seal_error, 627 seal_no_progress, 628 seal_partial, 629 seal_success, 630 }; 631 632 // seal_next_message seals |msg|, which must be the next message, to |out|. If 633 // progress was made, it returns |seal_partial| or |seal_success| and sets 634 // |*out_len| to the number of bytes written. 635 static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out, 636 size_t *out_len, size_t max_out, 637 const DTLS_OUTGOING_MESSAGE *msg) { 638 assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); 639 assert(msg == &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]); 640 641 enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch; 642 if (ssl->d1->w_epoch >= 1 && msg->epoch == ssl->d1->w_epoch - 1) { 643 use_epoch = dtls1_use_previous_epoch; 644 } else if (msg->epoch != ssl->d1->w_epoch) { 645 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 646 return seal_error; 647 } 648 649 size_t overhead = dtls_max_seal_overhead(ssl, use_epoch); 650 size_t prefix = dtls_seal_prefix_len(ssl, use_epoch); 651 652 if (msg->is_ccs) { 653 // Check there is room for the ChangeCipherSpec. 654 static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS}; 655 if (max_out < sizeof(kChangeCipherSpec) + overhead) { 656 return seal_no_progress; 657 } 658 659 if (!dtls_seal_record(ssl, out, out_len, max_out, 660 SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, 661 sizeof(kChangeCipherSpec), use_epoch)) { 662 return seal_error; 663 } 664 665 ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC, 666 kChangeCipherSpec); 667 return seal_success; 668 } 669 670 // DTLS messages are serialized as a single fragment in |msg|. 671 CBS cbs, body; 672 struct hm_header_st hdr; 673 CBS_init(&cbs, msg->data, msg->len); 674 if (!dtls1_parse_fragment(&cbs, &hdr, &body) || 675 hdr.frag_off != 0 || 676 hdr.frag_len != CBS_len(&body) || 677 hdr.msg_len != CBS_len(&body) || 678 !CBS_skip(&body, ssl->d1->outgoing_offset) || 679 CBS_len(&cbs) != 0) { 680 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 681 return seal_error; 682 } 683 684 // Determine how much progress can be made. 685 if (max_out < DTLS1_HM_HEADER_LENGTH + 1 + overhead || max_out < prefix) { 686 return seal_no_progress; 687 } 688 size_t todo = CBS_len(&body); 689 if (todo > max_out - DTLS1_HM_HEADER_LENGTH - overhead) { 690 todo = max_out - DTLS1_HM_HEADER_LENGTH - overhead; 691 } 692 693 // Assemble a fragment, to be sealed in-place. 694 ScopedCBB cbb; 695 uint8_t *frag = out + prefix; 696 size_t max_frag = max_out - prefix, frag_len; 697 if (!CBB_init_fixed(cbb.get(), frag, max_frag) || 698 !CBB_add_u8(cbb.get(), hdr.type) || 699 !CBB_add_u24(cbb.get(), hdr.msg_len) || 700 !CBB_add_u16(cbb.get(), hdr.seq) || 701 !CBB_add_u24(cbb.get(), ssl->d1->outgoing_offset) || 702 !CBB_add_u24(cbb.get(), todo) || 703 !CBB_add_bytes(cbb.get(), CBS_data(&body), todo) || 704 !CBB_finish(cbb.get(), NULL, &frag_len)) { 705 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 706 return seal_error; 707 } 708 709 ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, 710 MakeSpan(frag, frag_len)); 711 712 if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_HANDSHAKE, 713 out + prefix, frag_len, use_epoch)) { 714 return seal_error; 715 } 716 717 if (todo == CBS_len(&body)) { 718 // The next message is complete. 719 ssl->d1->outgoing_offset = 0; 720 return seal_success; 721 } 722 723 ssl->d1->outgoing_offset += todo; 724 return seal_partial; 725 } 726 727 // seal_next_packet writes as much of the next flight as possible to |out| and 728 // advances |ssl->d1->outgoing_written| and |ssl->d1->outgoing_offset| as 729 // appropriate. 730 static bool seal_next_packet(SSL *ssl, uint8_t *out, size_t *out_len, 731 size_t max_out) { 732 bool made_progress = false; 733 size_t total = 0; 734 assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); 735 for (; ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len; 736 ssl->d1->outgoing_written++) { 737 const DTLS_OUTGOING_MESSAGE *msg = 738 &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]; 739 size_t len; 740 enum seal_result_t ret = seal_next_message(ssl, out, &len, max_out, msg); 741 switch (ret) { 742 case seal_error: 743 return false; 744 745 case seal_no_progress: 746 goto packet_full; 747 748 case seal_partial: 749 case seal_success: 750 out += len; 751 max_out -= len; 752 total += len; 753 made_progress = true; 754 755 if (ret == seal_partial) { 756 goto packet_full; 757 } 758 break; 759 } 760 } 761 762 packet_full: 763 // The MTU was too small to make any progress. 764 if (!made_progress) { 765 OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL); 766 return false; 767 } 768 769 *out_len = total; 770 return true; 771 } 772 773 static int send_flight(SSL *ssl) { 774 if (ssl->s3->write_shutdown != ssl_shutdown_none) { 775 OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN); 776 return -1; 777 } 778 779 dtls1_update_mtu(ssl); 780 781 int ret = -1; 782 uint8_t *packet = (uint8_t *)OPENSSL_malloc(ssl->d1->mtu); 783 if (packet == NULL) { 784 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 785 goto err; 786 } 787 788 while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len) { 789 uint8_t old_written = ssl->d1->outgoing_written; 790 uint32_t old_offset = ssl->d1->outgoing_offset; 791 792 size_t packet_len; 793 if (!seal_next_packet(ssl, packet, &packet_len, ssl->d1->mtu)) { 794 goto err; 795 } 796 797 int bio_ret = BIO_write(ssl->wbio.get(), packet, packet_len); 798 if (bio_ret <= 0) { 799 // Retry this packet the next time around. 800 ssl->d1->outgoing_written = old_written; 801 ssl->d1->outgoing_offset = old_offset; 802 ssl->s3->rwstate = SSL_WRITING; 803 ret = bio_ret; 804 goto err; 805 } 806 } 807 808 if (BIO_flush(ssl->wbio.get()) <= 0) { 809 ssl->s3->rwstate = SSL_WRITING; 810 goto err; 811 } 812 813 ret = 1; 814 815 err: 816 OPENSSL_free(packet); 817 return ret; 818 } 819 820 int dtls1_flush_flight(SSL *ssl) { 821 ssl->d1->outgoing_messages_complete = true; 822 // Start the retransmission timer for the next flight (if any). 823 dtls1_start_timer(ssl); 824 return send_flight(ssl); 825 } 826 827 int dtls1_retransmit_outgoing_messages(SSL *ssl) { 828 // Rewind to the start of the flight and write it again. 829 // 830 // TODO(davidben): This does not allow retransmits to be resumed on 831 // non-blocking write. 832 ssl->d1->outgoing_written = 0; 833 ssl->d1->outgoing_offset = 0; 834 835 return send_flight(ssl); 836 } 837 838 unsigned int dtls1_min_mtu(void) { 839 return kMinMTU; 840 } 841 842 BSSL_NAMESPACE_END 843
