1 /* DTLS implementation written by Nagendra Modadugu 2 * (nagendra (at) cs.stanford.edu) for the OpenSSL project 2005. */ 3 /* ==================================================================== 4 * Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 18 * 3. All advertising materials mentioning features or use of this 19 * software must display the following acknowledgment: 20 * "This product includes software developed by the OpenSSL Project 21 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 22 * 23 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 24 * endorse or promote products derived from this software without 25 * prior written permission. For written permission, please contact 26 * openssl-core (at) openssl.org. 27 * 28 * 5. Products derived from this software may not be called "OpenSSL" 29 * nor may "OpenSSL" appear in their names without prior written 30 * permission of the OpenSSL Project. 31 * 32 * 6. Redistributions of any form whatsoever must retain the following 33 * acknowledgment: 34 * "This product includes software developed by the OpenSSL Project 35 * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 38 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 40 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 43 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 44 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 46 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 47 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 48 * OF THE POSSIBILITY OF SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This product includes cryptographic software written by Eric Young 52 * (eay (at) cryptsoft.com). This product includes software written by Tim 53 * Hudson (tjh (at) cryptsoft.com). 54 * 55 */ 56 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 57 * All rights reserved. 58 * 59 * This package is an SSL implementation written 60 * by Eric Young (eay (at) cryptsoft.com). 61 * The implementation was written so as to conform with Netscapes SSL. 62 * 63 * This library is free for commercial and non-commercial use as long as 64 * the following conditions are aheared to. The following conditions 65 * apply to all code found in this distribution, be it the RC4, RSA, 66 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 67 * included with this distribution is covered by the same copyright terms 68 * except that the holder is Tim Hudson (tjh (at) cryptsoft.com). 69 * 70 * Copyright remains Eric Young's, and as such any Copyright notices in 71 * the code are not to be removed. 72 * If this package is used in a product, Eric Young should be given attribution 73 * as the author of the parts of the library used. 74 * This can be in the form of a textual message at program startup or 75 * in documentation (online or textual) provided with the package. 76 * 77 * Redistribution and use in source and binary forms, with or without 78 * modification, are permitted provided that the following conditions 79 * are met: 80 * 1. Redistributions of source code must retain the copyright 81 * notice, this list of conditions and the following disclaimer. 82 * 2. Redistributions in binary form must reproduce the above copyright 83 * notice, this list of conditions and the following disclaimer in the 84 * documentation and/or other materials provided with the distribution. 85 * 3. All advertising materials mentioning features or use of this software 86 * must display the following acknowledgement: 87 * "This product includes cryptographic software written by 88 * Eric Young (eay (at) cryptsoft.com)" 89 * The word 'cryptographic' can be left out if the rouines from the library 90 * being used are not cryptographic related :-). 91 * 4. If you include any Windows specific code (or a derivative thereof) from 92 * the apps directory (application code) you must include an acknowledgement: 93 * "This product includes software written by Tim Hudson (tjh (at) cryptsoft.com)" 94 * 95 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 96 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 97 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 98 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 99 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 100 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 101 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 102 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 103 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 104 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 105 * SUCH DAMAGE. 106 * 107 * The licence and distribution terms for any publically available version or 108 * derivative of this code cannot be changed. i.e. this code cannot simply be 109 * copied and put under another distribution licence 110 * [including the GNU Public Licence.] */ 111 112 #include <openssl/ssl.h> 113 114 #include <assert.h> 115 #include <stdio.h> 116 #include <string.h> 117 118 #include <openssl/buf.h> 119 #include <openssl/mem.h> 120 #include <openssl/evp.h> 121 #include <openssl/err.h> 122 #include <openssl/rand.h> 123 124 #include "internal.h" 125 126 127 static int do_dtls1_write(SSL *ssl, int type, const uint8_t *buf, 128 unsigned int len, enum dtls1_use_epoch_t use_epoch); 129 130 /* dtls1_get_record reads a new input record. On success, it places it in 131 * |ssl->s3->rrec| and returns one. Otherwise it returns <= 0 on error or if 132 * more data is needed. */ 133 static int dtls1_get_record(SSL *ssl) { 134 again: 135 /* Read a new packet if there is no unconsumed one. */ 136 if (ssl_read_buffer_len(ssl) == 0) { 137 int ret = ssl_read_buffer_extend_to(ssl, 0 /* unused */); 138 if (ret <= 0) { 139 return ret; 140 } 141 } 142 assert(ssl_read_buffer_len(ssl) > 0); 143 144 /* Ensure the packet is large enough to decrypt in-place. */ 145 if (ssl_read_buffer_len(ssl) < ssl_record_prefix_len(ssl)) { 146 ssl_read_buffer_clear(ssl); 147 goto again; 148 } 149 150 uint8_t *out = ssl_read_buffer(ssl) + ssl_record_prefix_len(ssl); 151 size_t max_out = ssl_read_buffer_len(ssl) - ssl_record_prefix_len(ssl); 152 uint8_t type, alert; 153 size_t len, consumed; 154 switch (dtls_open_record(ssl, &type, out, &len, &consumed, &alert, max_out, 155 ssl_read_buffer(ssl), ssl_read_buffer_len(ssl))) { 156 case ssl_open_record_success: 157 ssl_read_buffer_consume(ssl, consumed); 158 159 if (len > 0xffff) { 160 OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); 161 return -1; 162 } 163 164 SSL3_RECORD *rr = &ssl->s3->rrec; 165 rr->type = type; 166 rr->length = (uint16_t)len; 167 rr->data = out; 168 return 1; 169 170 case ssl_open_record_discard: 171 ssl_read_buffer_consume(ssl, consumed); 172 goto again; 173 174 case ssl_open_record_error: 175 ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); 176 return -1; 177 178 case ssl_open_record_partial: 179 /* Impossible in DTLS. */ 180 break; 181 } 182 183 assert(0); 184 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 185 return -1; 186 } 187 188 int dtls1_read_app_data(SSL *ssl, uint8_t *buf, int len, int peek) { 189 return dtls1_read_bytes(ssl, SSL3_RT_APPLICATION_DATA, buf, len, peek); 190 } 191 192 int dtls1_read_change_cipher_spec(SSL *ssl) { 193 uint8_t byte; 194 int ret = dtls1_read_bytes(ssl, SSL3_RT_CHANGE_CIPHER_SPEC, &byte, 195 1 /* len */, 0 /* no peek */); 196 if (ret <= 0) { 197 return ret; 198 } 199 assert(ret == 1); 200 201 if (ssl->s3->rrec.length != 0 || byte != SSL3_MT_CCS) { 202 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_CHANGE_CIPHER_SPEC); 203 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); 204 return -1; 205 } 206 207 if (ssl->msg_callback != NULL) { 208 ssl->msg_callback(0, ssl->version, SSL3_RT_CHANGE_CIPHER_SPEC, &byte, 1, 209 ssl, ssl->msg_callback_arg); 210 } 211 212 return 1; 213 } 214 215 void dtls1_read_close_notify(SSL *ssl) { 216 /* Bidirectional shutdown doesn't make sense for an unordered transport. DTLS 217 * alerts also aren't delivered reliably, so we may even time out because the 218 * peer never received our close_notify. Report to the caller that the channel 219 * has fully shut down. */ 220 ssl->shutdown |= SSL_RECEIVED_SHUTDOWN; 221 } 222 223 /* Return up to 'len' payload bytes received in 'type' records. 224 * 'type' is one of the following: 225 * 226 * - SSL3_RT_HANDSHAKE (when dtls1_get_message calls us) 227 * - SSL3_RT_CHANGE_CIPHER_SPEC (when dtls1_read_change_cipher_spec calls us) 228 * - SSL3_RT_APPLICATION_DATA (when dtls1_read_app_data calls us) 229 * 230 * If we don't have stored data to work from, read a DTLS record first (possibly 231 * multiple records if we still don't have anything to return). 232 * 233 * This function must handle any surprises the peer may have for us, such as 234 * Alert records (e.g. close_notify) and out of records. */ 235 int dtls1_read_bytes(SSL *ssl, int type, unsigned char *buf, int len, int peek) { 236 int al, i, ret; 237 unsigned int n; 238 SSL3_RECORD *rr; 239 void (*cb)(const SSL *ssl, int type, int value) = NULL; 240 241 if ((type != SSL3_RT_APPLICATION_DATA && type != SSL3_RT_HANDSHAKE && 242 type != SSL3_RT_CHANGE_CIPHER_SPEC) || 243 (peek && type != SSL3_RT_APPLICATION_DATA)) { 244 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 245 return -1; 246 } 247 248 if (!ssl->in_handshake && SSL_in_init(ssl)) { 249 /* type == SSL3_RT_APPLICATION_DATA */ 250 i = ssl->handshake_func(ssl); 251 if (i < 0) { 252 return i; 253 } 254 if (i == 0) { 255 OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE); 256 return -1; 257 } 258 } 259 260 start: 261 ssl->rwstate = SSL_NOTHING; 262 263 /* ssl->s3->rrec.type - is the type of record 264 * ssl->s3->rrec.data - data 265 * ssl->s3->rrec.off - offset into 'data' for next read 266 * ssl->s3->rrec.length - number of bytes. */ 267 rr = &ssl->s3->rrec; 268 269 /* Check for timeout */ 270 if (DTLSv1_handle_timeout(ssl) > 0) { 271 goto start; 272 } 273 274 /* get new packet if necessary */ 275 if (rr->length == 0) { 276 ret = dtls1_get_record(ssl); 277 if (ret <= 0) { 278 ret = dtls1_read_failed(ssl, ret); 279 /* anything other than a timeout is an error */ 280 if (ret <= 0) { 281 return ret; 282 } else { 283 goto start; 284 } 285 } 286 } 287 288 /* we now have a packet which can be read and processed */ 289 290 /* If the other end has shut down, throw anything we read away (even in 291 * 'peek' mode) */ 292 if (ssl->shutdown & SSL_RECEIVED_SHUTDOWN) { 293 rr->length = 0; 294 ssl->rwstate = SSL_NOTHING; 295 return 0; 296 } 297 298 299 if (type == rr->type) { 300 /* Make sure that we are not getting application data when we 301 * are doing a handshake for the first time. */ 302 if (SSL_in_init(ssl) && (type == SSL3_RT_APPLICATION_DATA) && 303 (ssl->aead_read_ctx == NULL)) { 304 /* TODO(davidben): Is this check redundant with the handshake_func 305 * check? */ 306 al = SSL_AD_UNEXPECTED_MESSAGE; 307 OPENSSL_PUT_ERROR(SSL, SSL_R_APP_DATA_IN_HANDSHAKE); 308 goto f_err; 309 } 310 311 /* Discard empty records. */ 312 if (rr->length == 0) { 313 goto start; 314 } 315 316 if (len <= 0) { 317 return len; 318 } 319 320 if ((unsigned int)len > rr->length) { 321 n = rr->length; 322 } else { 323 n = (unsigned int)len; 324 } 325 326 memcpy(buf, rr->data, n); 327 if (!peek) { 328 rr->length -= n; 329 rr->data += n; 330 if (rr->length == 0) { 331 /* The record has been consumed, so we may now clear the buffer. */ 332 ssl_read_buffer_discard(ssl); 333 } 334 } 335 336 return n; 337 } 338 339 /* If we get here, then type != rr->type. */ 340 341 /* If an alert record, process one alert out of the record. Note that we allow 342 * a single record to contain multiple alerts. */ 343 if (rr->type == SSL3_RT_ALERT) { 344 /* Alerts may not be fragmented. */ 345 if (rr->length < 2) { 346 al = SSL_AD_DECODE_ERROR; 347 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ALERT); 348 goto f_err; 349 } 350 351 if (ssl->msg_callback) { 352 ssl->msg_callback(0, ssl->version, SSL3_RT_ALERT, rr->data, 2, ssl, 353 ssl->msg_callback_arg); 354 } 355 const uint8_t alert_level = rr->data[0]; 356 const uint8_t alert_descr = rr->data[1]; 357 rr->length -= 2; 358 rr->data += 2; 359 360 if (ssl->info_callback != NULL) { 361 cb = ssl->info_callback; 362 } else if (ssl->ctx->info_callback != NULL) { 363 cb = ssl->ctx->info_callback; 364 } 365 366 if (cb != NULL) { 367 uint16_t alert = (alert_level << 8) | alert_descr; 368 cb(ssl, SSL_CB_READ_ALERT, alert); 369 } 370 371 if (alert_level == SSL3_AL_WARNING) { 372 ssl->s3->warn_alert = alert_descr; 373 if (alert_descr == SSL_AD_CLOSE_NOTIFY) { 374 ssl->shutdown |= SSL_RECEIVED_SHUTDOWN; 375 return 0; 376 } 377 } else if (alert_level == SSL3_AL_FATAL) { 378 char tmp[16]; 379 380 ssl->rwstate = SSL_NOTHING; 381 ssl->s3->fatal_alert = alert_descr; 382 OPENSSL_PUT_ERROR(SSL, SSL_AD_REASON_OFFSET + alert_descr); 383 BIO_snprintf(tmp, sizeof tmp, "%d", alert_descr); 384 ERR_add_error_data(2, "SSL alert number ", tmp); 385 ssl->shutdown |= SSL_RECEIVED_SHUTDOWN; 386 SSL_CTX_remove_session(ssl->ctx, ssl->session); 387 return 0; 388 } else { 389 al = SSL_AD_ILLEGAL_PARAMETER; 390 OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_ALERT_TYPE); 391 goto f_err; 392 } 393 394 goto start; 395 } 396 397 /* Cross-epoch records are discarded, but we may receive out-of-order 398 * application data between ChangeCipherSpec and Finished or a ChangeCipherSpec 399 * before the appropriate point in the handshake. Those must be silently 400 * discarded. 401 * 402 * However, only allow the out-of-order records in the correct epoch. 403 * Application data must come in the encrypted epoch, and ChangeCipherSpec in 404 * the unencrypted epoch (we never renegotiate). Other cases fall through and 405 * fail with a fatal error. */ 406 if ((rr->type == SSL3_RT_APPLICATION_DATA && ssl->aead_read_ctx != NULL) || 407 (rr->type == SSL3_RT_CHANGE_CIPHER_SPEC && ssl->aead_read_ctx == NULL)) { 408 rr->length = 0; 409 goto start; 410 } 411 412 if (rr->type == SSL3_RT_HANDSHAKE) { 413 if (type != SSL3_RT_APPLICATION_DATA) { 414 /* Out-of-order handshake record while looking for ChangeCipherSpec. Drop 415 * it silently. */ 416 assert(type == SSL3_RT_CHANGE_CIPHER_SPEC); 417 rr->length = 0; 418 goto start; 419 } 420 421 /* Parse the first fragment header to determine if this is a pre-CCS or 422 * post-CCS handshake record. DTLS resets handshake message numbers on each 423 * handshake, so renegotiations and retransmissions are ambiguous. */ 424 if (rr->length < DTLS1_HM_HEADER_LENGTH) { 425 al = SSL_AD_DECODE_ERROR; 426 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD); 427 goto f_err; 428 } 429 struct hm_header_st msg_hdr; 430 dtls1_get_message_header(rr->data, &msg_hdr); 431 432 if (msg_hdr.type == SSL3_MT_FINISHED) { 433 if (msg_hdr.frag_off == 0) { 434 /* Retransmit our last flight of messages. If the peer sends the second 435 * Finished, they may not have received ours. Only do this for the 436 * first fragment, in case the Finished was fragmented. */ 437 if (dtls1_check_timeout_num(ssl) < 0) { 438 return -1; 439 } 440 441 dtls1_retransmit_buffered_messages(ssl); 442 } 443 444 rr->length = 0; 445 goto start; 446 } 447 448 /* Otherwise, this is a pre-CCS handshake message from an unsupported 449 * renegotiation attempt. Fall through to the error path. */ 450 } 451 452 al = SSL_AD_UNEXPECTED_MESSAGE; 453 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 454 455 f_err: 456 ssl3_send_alert(ssl, SSL3_AL_FATAL, al); 457 return -1; 458 } 459 460 int dtls1_write_app_data(SSL *ssl, const void *buf_, int len) { 461 int i; 462 463 if (SSL_in_init(ssl) && !ssl->in_handshake) { 464 i = ssl->handshake_func(ssl); 465 if (i < 0) { 466 return i; 467 } 468 if (i == 0) { 469 OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE); 470 return -1; 471 } 472 } 473 474 if (len > SSL3_RT_MAX_PLAIN_LENGTH) { 475 OPENSSL_PUT_ERROR(SSL, SSL_R_DTLS_MESSAGE_TOO_BIG); 476 return -1; 477 } 478 479 i = dtls1_write_bytes(ssl, SSL3_RT_APPLICATION_DATA, buf_, len, 480 dtls1_use_current_epoch); 481 return i; 482 } 483 484 /* Call this to write data in records of type 'type' It will return <= 0 if not 485 * all data has been sent or non-blocking IO. */ 486 int dtls1_write_bytes(SSL *ssl, int type, const void *buf, int len, 487 enum dtls1_use_epoch_t use_epoch) { 488 int i; 489 490 assert(len <= SSL3_RT_MAX_PLAIN_LENGTH); 491 ssl->rwstate = SSL_NOTHING; 492 i = do_dtls1_write(ssl, type, buf, len, use_epoch); 493 return i; 494 } 495 496 static int do_dtls1_write(SSL *ssl, int type, const uint8_t *buf, 497 unsigned int len, enum dtls1_use_epoch_t use_epoch) { 498 /* There should never be a pending write buffer in DTLS. One can't write half 499 * a datagram, so the write buffer is always dropped in 500 * |ssl_write_buffer_flush|. */ 501 assert(!ssl_write_buffer_is_pending(ssl)); 502 503 /* If we have an alert to send, lets send it */ 504 if (ssl->s3->alert_dispatch) { 505 int ret = ssl->method->ssl_dispatch_alert(ssl); 506 if (ret <= 0) { 507 return ret; 508 } 509 /* if it went, fall through and send more stuff */ 510 } 511 512 if (len > SSL3_RT_MAX_PLAIN_LENGTH) { 513 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 514 return -1; 515 } 516 517 if (len == 0) { 518 return 0; 519 } 520 521 size_t max_out = len + ssl_max_seal_overhead(ssl); 522 uint8_t *out; 523 size_t ciphertext_len; 524 if (!ssl_write_buffer_init(ssl, &out, max_out) || 525 !dtls_seal_record(ssl, out, &ciphertext_len, max_out, type, buf, len, 526 use_epoch)) { 527 ssl_write_buffer_clear(ssl); 528 return -1; 529 } 530 ssl_write_buffer_set_len(ssl, ciphertext_len); 531 532 int ret = ssl_write_buffer_flush(ssl); 533 if (ret <= 0) { 534 return ret; 535 } 536 return (int)len; 537 } 538 539 int dtls1_dispatch_alert(SSL *ssl) { 540 int i, j; 541 void (*cb)(const SSL *ssl, int type, int value) = NULL; 542 uint8_t buf[DTLS1_AL_HEADER_LENGTH]; 543 uint8_t *ptr = &buf[0]; 544 545 ssl->s3->alert_dispatch = 0; 546 547 memset(buf, 0x00, sizeof(buf)); 548 *ptr++ = ssl->s3->send_alert[0]; 549 *ptr++ = ssl->s3->send_alert[1]; 550 551 i = do_dtls1_write(ssl, SSL3_RT_ALERT, &buf[0], sizeof(buf), 552 dtls1_use_current_epoch); 553 if (i <= 0) { 554 ssl->s3->alert_dispatch = 1; 555 } else { 556 if (ssl->s3->send_alert[0] == SSL3_AL_FATAL) { 557 (void)BIO_flush(ssl->wbio); 558 } 559 560 if (ssl->msg_callback) { 561 ssl->msg_callback(1, ssl->version, SSL3_RT_ALERT, ssl->s3->send_alert, 2, 562 ssl, ssl->msg_callback_arg); 563 } 564 565 if (ssl->info_callback != NULL) { 566 cb = ssl->info_callback; 567 } else if (ssl->ctx->info_callback != NULL) { 568 cb = ssl->ctx->info_callback; 569 } 570 571 if (cb != NULL) { 572 j = (ssl->s3->send_alert[0] << 8) | ssl->s3->send_alert[1]; 573 cb(ssl, SSL_CB_WRITE_ALERT, j); 574 } 575 } 576 577 return i; 578 } 579
