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 #include <openssl/type_check.h> 126 127 #include "../crypto/internal.h" 128 #include "internal.h" 129 130 131 /* TODO(davidben): 28 comes from the size of IP + UDP header. Is this reasonable 132 * for these values? Notably, why is kMinMTU a function of the transport 133 * protocol's overhead rather than, say, what's needed to hold a minimally-sized 134 * handshake fragment plus protocol overhead. */ 135 136 /* kMinMTU is the minimum acceptable MTU value. */ 137 static const unsigned int kMinMTU = 256 - 28; 138 139 /* kDefaultMTU is the default MTU value to use if neither the user nor 140 * the underlying BIO supplies one. */ 141 static const unsigned int kDefaultMTU = 1500 - 28; 142 143 144 /* Receiving handshake messages. */ 145 146 static void dtls1_hm_fragment_free(hm_fragment *frag) { 147 if (frag == NULL) { 148 return; 149 } 150 OPENSSL_free(frag->data); 151 OPENSSL_free(frag->reassembly); 152 OPENSSL_free(frag); 153 } 154 155 static hm_fragment *dtls1_hm_fragment_new(const struct hm_header_st *msg_hdr) { 156 hm_fragment *frag = OPENSSL_malloc(sizeof(hm_fragment)); 157 if (frag == NULL) { 158 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 159 return NULL; 160 } 161 OPENSSL_memset(frag, 0, sizeof(hm_fragment)); 162 frag->type = msg_hdr->type; 163 frag->seq = msg_hdr->seq; 164 frag->msg_len = msg_hdr->msg_len; 165 166 /* Allocate space for the reassembled message and fill in the header. */ 167 frag->data = OPENSSL_malloc(DTLS1_HM_HEADER_LENGTH + msg_hdr->msg_len); 168 if (frag->data == NULL) { 169 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 170 goto err; 171 } 172 173 CBB cbb; 174 if (!CBB_init_fixed(&cbb, frag->data, DTLS1_HM_HEADER_LENGTH) || 175 !CBB_add_u8(&cbb, msg_hdr->type) || 176 !CBB_add_u24(&cbb, msg_hdr->msg_len) || 177 !CBB_add_u16(&cbb, msg_hdr->seq) || 178 !CBB_add_u24(&cbb, 0 /* frag_off */) || 179 !CBB_add_u24(&cbb, msg_hdr->msg_len) || 180 !CBB_finish(&cbb, NULL, NULL)) { 181 CBB_cleanup(&cbb); 182 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 183 goto err; 184 } 185 186 /* If the handshake message is empty, |frag->reassembly| is NULL. */ 187 if (msg_hdr->msg_len > 0) { 188 /* Initialize reassembly bitmask. */ 189 if (msg_hdr->msg_len + 7 < msg_hdr->msg_len) { 190 OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); 191 goto err; 192 } 193 size_t bitmask_len = (msg_hdr->msg_len + 7) / 8; 194 frag->reassembly = OPENSSL_malloc(bitmask_len); 195 if (frag->reassembly == NULL) { 196 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 197 goto err; 198 } 199 OPENSSL_memset(frag->reassembly, 0, bitmask_len); 200 } 201 202 return frag; 203 204 err: 205 dtls1_hm_fragment_free(frag); 206 return NULL; 207 } 208 209 /* bit_range returns a |uint8_t| with bits |start|, inclusive, to |end|, 210 * exclusive, set. */ 211 static uint8_t bit_range(size_t start, size_t end) { 212 return (uint8_t)(~((1u << start) - 1) & ((1u << end) - 1)); 213 } 214 215 /* dtls1_hm_fragment_mark marks bytes |start|, inclusive, to |end|, exclusive, 216 * as received in |frag|. If |frag| becomes complete, it clears 217 * |frag->reassembly|. The range must be within the bounds of |frag|'s message 218 * and |frag->reassembly| must not be NULL. */ 219 static void dtls1_hm_fragment_mark(hm_fragment *frag, size_t start, 220 size_t end) { 221 size_t msg_len = frag->msg_len; 222 223 if (frag->reassembly == NULL || start > end || end > msg_len) { 224 assert(0); 225 return; 226 } 227 /* A zero-length message will never have a pending reassembly. */ 228 assert(msg_len > 0); 229 230 if ((start >> 3) == (end >> 3)) { 231 frag->reassembly[start >> 3] |= bit_range(start & 7, end & 7); 232 } else { 233 frag->reassembly[start >> 3] |= bit_range(start & 7, 8); 234 for (size_t i = (start >> 3) + 1; i < (end >> 3); i++) { 235 frag->reassembly[i] = 0xff; 236 } 237 if ((end & 7) != 0) { 238 frag->reassembly[end >> 3] |= bit_range(0, end & 7); 239 } 240 } 241 242 /* Check if the fragment is complete. */ 243 for (size_t i = 0; i < (msg_len >> 3); i++) { 244 if (frag->reassembly[i] != 0xff) { 245 return; 246 } 247 } 248 if ((msg_len & 7) != 0 && 249 frag->reassembly[msg_len >> 3] != bit_range(0, msg_len & 7)) { 250 return; 251 } 252 253 OPENSSL_free(frag->reassembly); 254 frag->reassembly = NULL; 255 } 256 257 /* dtls1_is_current_message_complete returns one if the current handshake 258 * message is complete and zero otherwise. */ 259 static int dtls1_is_current_message_complete(const SSL *ssl) { 260 hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % 261 SSL_MAX_HANDSHAKE_FLIGHT]; 262 return frag != NULL && frag->reassembly == NULL; 263 } 264 265 /* dtls1_get_incoming_message returns the incoming message corresponding to 266 * |msg_hdr|. If none exists, it creates a new one and inserts it in the 267 * queue. Otherwise, it checks |msg_hdr| is consistent with the existing one. It 268 * returns NULL on failure. The caller does not take ownership of the result. */ 269 static hm_fragment *dtls1_get_incoming_message( 270 SSL *ssl, const struct hm_header_st *msg_hdr) { 271 if (msg_hdr->seq < ssl->d1->handshake_read_seq || 272 msg_hdr->seq - ssl->d1->handshake_read_seq >= SSL_MAX_HANDSHAKE_FLIGHT) { 273 return NULL; 274 } 275 276 size_t idx = msg_hdr->seq % SSL_MAX_HANDSHAKE_FLIGHT; 277 hm_fragment *frag = ssl->d1->incoming_messages[idx]; 278 if (frag != NULL) { 279 assert(frag->seq == msg_hdr->seq); 280 /* The new fragment must be compatible with the previous fragments from this 281 * message. */ 282 if (frag->type != msg_hdr->type || 283 frag->msg_len != msg_hdr->msg_len) { 284 OPENSSL_PUT_ERROR(SSL, SSL_R_FRAGMENT_MISMATCH); 285 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); 286 return NULL; 287 } 288 return frag; 289 } 290 291 /* This is the first fragment from this message. */ 292 frag = dtls1_hm_fragment_new(msg_hdr); 293 if (frag == NULL) { 294 return NULL; 295 } 296 ssl->d1->incoming_messages[idx] = frag; 297 return frag; 298 } 299 300 /* dtls1_process_handshake_record reads a handshake record and processes it. It 301 * returns one if the record was successfully processed and 0 or -1 on error. */ 302 static int dtls1_process_handshake_record(SSL *ssl) { 303 SSL3_RECORD *rr = &ssl->s3->rrec; 304 305 start: 306 if (rr->length == 0) { 307 int ret = dtls1_get_record(ssl); 308 if (ret <= 0) { 309 return ret; 310 } 311 } 312 313 /* Cross-epoch records are discarded, but we may receive out-of-order 314 * application data between ChangeCipherSpec and Finished or a 315 * ChangeCipherSpec before the appropriate point in the handshake. Those must 316 * be silently discarded. 317 * 318 * However, only allow the out-of-order records in the correct epoch. 319 * Application data must come in the encrypted epoch, and ChangeCipherSpec in 320 * the unencrypted epoch (we never renegotiate). Other cases fall through and 321 * fail with a fatal error. */ 322 if ((rr->type == SSL3_RT_APPLICATION_DATA && 323 ssl->s3->aead_read_ctx != NULL) || 324 (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC && 325 ssl->s3->aead_read_ctx == NULL)) { 326 rr->length = 0; 327 goto start; 328 } 329 330 if (rr->type != SSL3_RT_HANDSHAKE) { 331 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); 332 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 333 return -1; 334 } 335 336 CBS cbs; 337 CBS_init(&cbs, rr->data, rr->length); 338 339 while (CBS_len(&cbs) > 0) { 340 /* Read a handshake fragment. */ 341 struct hm_header_st msg_hdr; 342 CBS body; 343 if (!dtls1_parse_fragment(&cbs, &msg_hdr, &body)) { 344 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD); 345 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); 346 return -1; 347 } 348 349 const size_t frag_off = msg_hdr.frag_off; 350 const size_t frag_len = msg_hdr.frag_len; 351 const size_t msg_len = msg_hdr.msg_len; 352 if (frag_off > msg_len || frag_off + frag_len < frag_off || 353 frag_off + frag_len > msg_len || 354 msg_len > ssl_max_handshake_message_len(ssl)) { 355 OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE); 356 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); 357 return -1; 358 } 359 360 /* The encrypted epoch in DTLS has only one handshake message. */ 361 if (ssl->d1->r_epoch == 1 && msg_hdr.seq != ssl->d1->handshake_read_seq) { 362 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 363 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); 364 return -1; 365 } 366 367 if (msg_hdr.seq < ssl->d1->handshake_read_seq || 368 msg_hdr.seq > 369 (unsigned)ssl->d1->handshake_read_seq + SSL_MAX_HANDSHAKE_FLIGHT) { 370 /* Ignore fragments from the past, or ones too far in the future. */ 371 continue; 372 } 373 374 hm_fragment *frag = dtls1_get_incoming_message(ssl, &msg_hdr); 375 if (frag == NULL) { 376 return -1; 377 } 378 assert(frag->msg_len == msg_len); 379 380 if (frag->reassembly == NULL) { 381 /* The message is already assembled. */ 382 continue; 383 } 384 assert(msg_len > 0); 385 386 /* Copy the body into the fragment. */ 387 OPENSSL_memcpy(frag->data + DTLS1_HM_HEADER_LENGTH + frag_off, 388 CBS_data(&body), CBS_len(&body)); 389 dtls1_hm_fragment_mark(frag, frag_off, frag_off + frag_len); 390 } 391 392 rr->length = 0; 393 ssl_read_buffer_discard(ssl); 394 return 1; 395 } 396 397 int dtls1_get_message(SSL *ssl) { 398 if (ssl->s3->tmp.reuse_message) { 399 /* There must be a current message. */ 400 assert(ssl->init_msg != NULL); 401 ssl->s3->tmp.reuse_message = 0; 402 } else { 403 dtls1_release_current_message(ssl, 0 /* don't free buffer */); 404 } 405 406 /* Process handshake records until the current message is ready. */ 407 while (!dtls1_is_current_message_complete(ssl)) { 408 int ret = dtls1_process_handshake_record(ssl); 409 if (ret <= 0) { 410 return ret; 411 } 412 } 413 414 hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % 415 SSL_MAX_HANDSHAKE_FLIGHT]; 416 assert(frag != NULL); 417 assert(frag->reassembly == NULL); 418 assert(ssl->d1->handshake_read_seq == frag->seq); 419 420 /* TODO(davidben): This function has a lot of implicit outputs. Simplify the 421 * |ssl_get_message| API. */ 422 ssl->s3->tmp.message_type = frag->type; 423 ssl->init_msg = frag->data + DTLS1_HM_HEADER_LENGTH; 424 ssl->init_num = frag->msg_len; 425 426 ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, frag->data, 427 ssl->init_num + DTLS1_HM_HEADER_LENGTH); 428 return 1; 429 } 430 431 void dtls1_get_current_message(const SSL *ssl, CBS *out) { 432 assert(dtls1_is_current_message_complete(ssl)); 433 434 hm_fragment *frag = ssl->d1->incoming_messages[ssl->d1->handshake_read_seq % 435 SSL_MAX_HANDSHAKE_FLIGHT]; 436 CBS_init(out, frag->data, DTLS1_HM_HEADER_LENGTH + frag->msg_len); 437 } 438 439 void dtls1_release_current_message(SSL *ssl, int free_buffer) { 440 if (ssl->init_msg == NULL) { 441 return; 442 } 443 444 assert(dtls1_is_current_message_complete(ssl)); 445 size_t index = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 446 dtls1_hm_fragment_free(ssl->d1->incoming_messages[index]); 447 ssl->d1->incoming_messages[index] = NULL; 448 ssl->d1->handshake_read_seq++; 449 450 ssl->init_msg = NULL; 451 ssl->init_num = 0; 452 } 453 454 void dtls_clear_incoming_messages(SSL *ssl) { 455 for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) { 456 dtls1_hm_fragment_free(ssl->d1->incoming_messages[i]); 457 ssl->d1->incoming_messages[i] = NULL; 458 } 459 } 460 461 int dtls_has_incoming_messages(const SSL *ssl) { 462 size_t current = ssl->d1->handshake_read_seq % SSL_MAX_HANDSHAKE_FLIGHT; 463 for (size_t i = 0; i < SSL_MAX_HANDSHAKE_FLIGHT; i++) { 464 /* Skip the current message. */ 465 if (ssl->init_msg != NULL && i == current) { 466 assert(dtls1_is_current_message_complete(ssl)); 467 continue; 468 } 469 if (ssl->d1->incoming_messages[i] != NULL) { 470 return 1; 471 } 472 } 473 return 0; 474 } 475 476 int dtls1_parse_fragment(CBS *cbs, struct hm_header_st *out_hdr, 477 CBS *out_body) { 478 OPENSSL_memset(out_hdr, 0x00, sizeof(struct hm_header_st)); 479 480 if (!CBS_get_u8(cbs, &out_hdr->type) || 481 !CBS_get_u24(cbs, &out_hdr->msg_len) || 482 !CBS_get_u16(cbs, &out_hdr->seq) || 483 !CBS_get_u24(cbs, &out_hdr->frag_off) || 484 !CBS_get_u24(cbs, &out_hdr->frag_len) || 485 !CBS_get_bytes(cbs, out_body, out_hdr->frag_len)) { 486 return 0; 487 } 488 489 return 1; 490 } 491 492 493 /* Sending handshake messages. */ 494 495 void dtls_clear_outgoing_messages(SSL *ssl) { 496 for (size_t i = 0; i < ssl->d1->outgoing_messages_len; i++) { 497 OPENSSL_free(ssl->d1->outgoing_messages[i].data); 498 ssl->d1->outgoing_messages[i].data = NULL; 499 } 500 ssl->d1->outgoing_messages_len = 0; 501 ssl->d1->outgoing_written = 0; 502 ssl->d1->outgoing_offset = 0; 503 } 504 505 int dtls1_init_message(SSL *ssl, CBB *cbb, CBB *body, uint8_t type) { 506 /* Pick a modest size hint to save most of the |realloc| calls. */ 507 if (!CBB_init(cbb, 64) || 508 !CBB_add_u8(cbb, type) || 509 !CBB_add_u24(cbb, 0 /* length (filled in later) */) || 510 !CBB_add_u16(cbb, ssl->d1->handshake_write_seq) || 511 !CBB_add_u24(cbb, 0 /* offset */) || 512 !CBB_add_u24_length_prefixed(cbb, body)) { 513 return 0; 514 } 515 516 return 1; 517 } 518 519 int dtls1_finish_message(SSL *ssl, CBB *cbb, uint8_t **out_msg, 520 size_t *out_len) { 521 *out_msg = NULL; 522 if (!CBB_finish(cbb, out_msg, out_len) || 523 *out_len < DTLS1_HM_HEADER_LENGTH) { 524 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 525 OPENSSL_free(*out_msg); 526 return 0; 527 } 528 529 /* Fix up the header. Copy the fragment length into the total message 530 * length. */ 531 OPENSSL_memcpy(*out_msg + 1, *out_msg + DTLS1_HM_HEADER_LENGTH - 3, 3); 532 return 1; 533 } 534 535 /* add_outgoing adds a new handshake message or ChangeCipherSpec to the current 536 * outgoing flight. It returns one on success and zero on error. In both cases, 537 * it takes ownership of |data| and releases it with |OPENSSL_free| when 538 * done. */ 539 static int add_outgoing(SSL *ssl, int is_ccs, uint8_t *data, size_t len) { 540 OPENSSL_COMPILE_ASSERT(SSL_MAX_HANDSHAKE_FLIGHT < 541 (1 << 8 * sizeof(ssl->d1->outgoing_messages_len)), 542 outgoing_messages_len_is_too_small); 543 if (ssl->d1->outgoing_messages_len >= SSL_MAX_HANDSHAKE_FLIGHT) { 544 assert(0); 545 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 546 OPENSSL_free(data); 547 return 0; 548 } 549 550 if (!is_ccs) { 551 /* TODO(svaldez): Move this up a layer to fix abstraction for SSL_TRANSCRIPT 552 * on hs. */ 553 if (ssl->s3->hs != NULL && 554 !SSL_TRANSCRIPT_update(&ssl->s3->hs->transcript, data, len)) { 555 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 556 OPENSSL_free(data); 557 return 0; 558 } 559 ssl->d1->handshake_write_seq++; 560 } 561 562 DTLS_OUTGOING_MESSAGE *msg = 563 &ssl->d1->outgoing_messages[ssl->d1->outgoing_messages_len]; 564 msg->data = data; 565 msg->len = len; 566 msg->epoch = ssl->d1->w_epoch; 567 msg->is_ccs = is_ccs; 568 569 ssl->d1->outgoing_messages_len++; 570 return 1; 571 } 572 573 int dtls1_add_message(SSL *ssl, uint8_t *data, size_t len) { 574 return add_outgoing(ssl, 0 /* handshake */, data, len); 575 } 576 577 int dtls1_add_change_cipher_spec(SSL *ssl) { 578 return add_outgoing(ssl, 1 /* ChangeCipherSpec */, NULL, 0); 579 } 580 581 int dtls1_add_alert(SSL *ssl, uint8_t level, uint8_t desc) { 582 /* The |add_alert| path is only used for warning alerts for now, which DTLS 583 * never sends. This will be implemented later once closure alerts are 584 * converted. */ 585 assert(0); 586 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 587 return 0; 588 } 589 590 /* dtls1_update_mtu updates the current MTU from the BIO, ensuring it is above 591 * the minimum. */ 592 static void dtls1_update_mtu(SSL *ssl) { 593 /* TODO(davidben): No consumer implements |BIO_CTRL_DGRAM_SET_MTU| and the 594 * only |BIO_CTRL_DGRAM_QUERY_MTU| implementation could use 595 * |SSL_set_mtu|. Does this need to be so complex? */ 596 if (ssl->d1->mtu < dtls1_min_mtu() && 597 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { 598 long mtu = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL); 599 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { 600 ssl->d1->mtu = (unsigned)mtu; 601 } else { 602 ssl->d1->mtu = kDefaultMTU; 603 BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_SET_MTU, ssl->d1->mtu, NULL); 604 } 605 } 606 607 /* The MTU should be above the minimum now. */ 608 assert(ssl->d1->mtu >= dtls1_min_mtu()); 609 } 610 611 enum seal_result_t { 612 seal_error, 613 seal_no_progress, 614 seal_partial, 615 seal_success, 616 }; 617 618 /* seal_next_message seals |msg|, which must be the next message, to |out|. If 619 * progress was made, it returns |seal_partial| or |seal_success| and sets 620 * |*out_len| to the number of bytes written. */ 621 static enum seal_result_t seal_next_message(SSL *ssl, uint8_t *out, 622 size_t *out_len, size_t max_out, 623 const DTLS_OUTGOING_MESSAGE *msg) { 624 assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); 625 assert(msg == &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]); 626 627 /* DTLS renegotiation is unsupported, so only epochs 0 (NULL cipher) and 1 628 * (negotiated cipher) exist. */ 629 assert(ssl->d1->w_epoch == 0 || ssl->d1->w_epoch == 1); 630 assert(msg->epoch <= ssl->d1->w_epoch); 631 enum dtls1_use_epoch_t use_epoch = dtls1_use_current_epoch; 632 if (ssl->d1->w_epoch == 1 && msg->epoch == 0) { 633 use_epoch = dtls1_use_previous_epoch; 634 } 635 size_t overhead = dtls_max_seal_overhead(ssl, use_epoch); 636 size_t prefix = dtls_seal_prefix_len(ssl, use_epoch); 637 638 if (msg->is_ccs) { 639 /* Check there is room for the ChangeCipherSpec. */ 640 static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS}; 641 if (max_out < sizeof(kChangeCipherSpec) + overhead) { 642 return seal_no_progress; 643 } 644 645 if (!dtls_seal_record(ssl, out, out_len, max_out, 646 SSL3_RT_CHANGE_CIPHER_SPEC, kChangeCipherSpec, 647 sizeof(kChangeCipherSpec), use_epoch)) { 648 return seal_error; 649 } 650 651 ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC, 652 kChangeCipherSpec, sizeof(kChangeCipherSpec)); 653 return seal_success; 654 } 655 656 /* DTLS messages are serialized as a single fragment in |msg|. */ 657 CBS cbs, body; 658 struct hm_header_st hdr; 659 CBS_init(&cbs, msg->data, msg->len); 660 if (!dtls1_parse_fragment(&cbs, &hdr, &body) || 661 hdr.frag_off != 0 || 662 hdr.frag_len != CBS_len(&body) || 663 hdr.msg_len != CBS_len(&body) || 664 !CBS_skip(&body, ssl->d1->outgoing_offset) || 665 CBS_len(&cbs) != 0) { 666 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 667 return seal_error; 668 } 669 670 /* Determine how much progress can be made. */ 671 if (max_out < DTLS1_HM_HEADER_LENGTH + 1 + overhead || max_out < prefix) { 672 return seal_no_progress; 673 } 674 size_t todo = CBS_len(&body); 675 if (todo > max_out - DTLS1_HM_HEADER_LENGTH - overhead) { 676 todo = max_out - DTLS1_HM_HEADER_LENGTH - overhead; 677 } 678 679 /* Assemble a fragment, to be sealed in-place. */ 680 CBB cbb; 681 uint8_t *frag = out + prefix; 682 size_t max_frag = max_out - prefix, frag_len; 683 if (!CBB_init_fixed(&cbb, frag, max_frag) || 684 !CBB_add_u8(&cbb, hdr.type) || 685 !CBB_add_u24(&cbb, hdr.msg_len) || 686 !CBB_add_u16(&cbb, hdr.seq) || 687 !CBB_add_u24(&cbb, ssl->d1->outgoing_offset) || 688 !CBB_add_u24(&cbb, todo) || 689 !CBB_add_bytes(&cbb, CBS_data(&body), todo) || 690 !CBB_finish(&cbb, NULL, &frag_len)) { 691 CBB_cleanup(&cbb); 692 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 693 return seal_error; 694 } 695 696 ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, frag, frag_len); 697 698 if (!dtls_seal_record(ssl, out, out_len, max_out, SSL3_RT_HANDSHAKE, 699 out + prefix, frag_len, use_epoch)) { 700 return seal_error; 701 } 702 703 if (todo == CBS_len(&body)) { 704 /* The next message is complete. */ 705 ssl->d1->outgoing_offset = 0; 706 return seal_success; 707 } 708 709 ssl->d1->outgoing_offset += todo; 710 return seal_partial; 711 } 712 713 /* seal_next_packet writes as much of the next flight as possible to |out| and 714 * advances |ssl->d1->outgoing_written| and |ssl->d1->outgoing_offset| as 715 * appropriate. */ 716 static int seal_next_packet(SSL *ssl, uint8_t *out, size_t *out_len, 717 size_t max_out) { 718 int made_progress = 0; 719 size_t total = 0; 720 assert(ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len); 721 for (; ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len; 722 ssl->d1->outgoing_written++) { 723 const DTLS_OUTGOING_MESSAGE *msg = 724 &ssl->d1->outgoing_messages[ssl->d1->outgoing_written]; 725 size_t len; 726 enum seal_result_t ret = seal_next_message(ssl, out, &len, max_out, msg); 727 switch (ret) { 728 case seal_error: 729 return 0; 730 731 case seal_no_progress: 732 goto packet_full; 733 734 case seal_partial: 735 case seal_success: 736 out += len; 737 max_out -= len; 738 total += len; 739 made_progress = 1; 740 741 if (ret == seal_partial) { 742 goto packet_full; 743 } 744 break; 745 } 746 } 747 748 packet_full: 749 /* The MTU was too small to make any progress. */ 750 if (!made_progress) { 751 OPENSSL_PUT_ERROR(SSL, SSL_R_MTU_TOO_SMALL); 752 return 0; 753 } 754 755 *out_len = total; 756 return 1; 757 } 758 759 int dtls1_flush_flight(SSL *ssl) { 760 dtls1_update_mtu(ssl); 761 762 int ret = -1; 763 uint8_t *packet = OPENSSL_malloc(ssl->d1->mtu); 764 if (packet == NULL) { 765 OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE); 766 goto err; 767 } 768 769 while (ssl->d1->outgoing_written < ssl->d1->outgoing_messages_len) { 770 uint8_t old_written = ssl->d1->outgoing_written; 771 uint32_t old_offset = ssl->d1->outgoing_offset; 772 773 size_t packet_len; 774 if (!seal_next_packet(ssl, packet, &packet_len, ssl->d1->mtu)) { 775 goto err; 776 } 777 778 int bio_ret = BIO_write(ssl->wbio, packet, packet_len); 779 if (bio_ret <= 0) { 780 /* Retry this packet the next time around. */ 781 ssl->d1->outgoing_written = old_written; 782 ssl->d1->outgoing_offset = old_offset; 783 ssl->rwstate = SSL_WRITING; 784 ret = bio_ret; 785 goto err; 786 } 787 } 788 789 if (BIO_flush(ssl->wbio) <= 0) { 790 ssl->rwstate = SSL_WRITING; 791 goto err; 792 } 793 794 ret = 1; 795 796 err: 797 OPENSSL_free(packet); 798 return ret; 799 } 800 801 int dtls1_retransmit_outgoing_messages(SSL *ssl) { 802 /* Rewind to the start of the flight and write it again. 803 * 804 * TODO(davidben): This does not allow retransmits to be resumed on 805 * non-blocking write. */ 806 ssl->d1->outgoing_written = 0; 807 ssl->d1->outgoing_offset = 0; 808 809 return dtls1_flush_flight(ssl); 810 } 811 812 unsigned int dtls1_min_mtu(void) { 813 return kMinMTU; 814 } 815
