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 <string.h> 116 117 #include <openssl/bio.h> 118 #include <openssl/buf.h> 119 #include <openssl/bytestring.h> 120 #include <openssl/mem.h> 121 #include <openssl/evp.h> 122 #include <openssl/err.h> 123 #include <openssl/rand.h> 124 125 #include "../crypto/internal.h" 126 #include "internal.h" 127 128 129 int dtls1_get_record(SSL *ssl) { 130 again: 131 switch (ssl->s3->recv_shutdown) { 132 case ssl_shutdown_none: 133 break; 134 case ssl_shutdown_fatal_alert: 135 OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN); 136 return -1; 137 case ssl_shutdown_close_notify: 138 return 0; 139 } 140 141 /* Read a new packet if there is no unconsumed one. */ 142 if (ssl_read_buffer_len(ssl) == 0) { 143 int read_ret = ssl_read_buffer_extend_to(ssl, 0 /* unused */); 144 if (read_ret < 0 && dtls1_is_timer_expired(ssl)) { 145 /* Historically, timeouts were handled implicitly if the caller did not 146 * handle them. 147 * 148 * TODO(davidben): This was to support blocking sockets but affected 149 * non-blocking sockets. Can it be removed? */ 150 int timeout_ret = DTLSv1_handle_timeout(ssl); 151 if (timeout_ret <= 0) { 152 return timeout_ret; 153 } 154 goto again; 155 } 156 if (read_ret <= 0) { 157 return read_ret; 158 } 159 } 160 assert(ssl_read_buffer_len(ssl) > 0); 161 162 CBS body; 163 uint8_t type, alert; 164 size_t consumed; 165 enum ssl_open_record_t open_ret = 166 dtls_open_record(ssl, &type, &body, &consumed, &alert, 167 ssl_read_buffer(ssl), ssl_read_buffer_len(ssl)); 168 ssl_read_buffer_consume(ssl, consumed); 169 switch (open_ret) { 170 case ssl_open_record_partial: 171 /* Impossible in DTLS. */ 172 break; 173 174 case ssl_open_record_success: 175 if (CBS_len(&body) > 0xffff) { 176 OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW); 177 return -1; 178 } 179 180 SSL3_RECORD *rr = &ssl->s3->rrec; 181 rr->type = type; 182 rr->length = (uint16_t)CBS_len(&body); 183 rr->data = (uint8_t *)CBS_data(&body); 184 return 1; 185 186 case ssl_open_record_discard: 187 goto again; 188 189 case ssl_open_record_close_notify: 190 return 0; 191 192 case ssl_open_record_fatal_alert: 193 return -1; 194 195 case ssl_open_record_error: 196 ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); 197 return -1; 198 } 199 200 assert(0); 201 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 202 return -1; 203 } 204 205 int dtls1_read_app_data(SSL *ssl, int *out_got_handshake, uint8_t *buf, int len, 206 int peek) { 207 assert(!SSL_in_init(ssl)); 208 209 *out_got_handshake = 0; 210 SSL3_RECORD *rr = &ssl->s3->rrec; 211 212 again: 213 if (rr->length == 0) { 214 int ret = dtls1_get_record(ssl); 215 if (ret <= 0) { 216 return ret; 217 } 218 } 219 220 if (rr->type == SSL3_RT_HANDSHAKE) { 221 /* Parse the first fragment header to determine if this is a pre-CCS or 222 * post-CCS handshake record. DTLS resets handshake message numbers on each 223 * handshake, so renegotiations and retransmissions are ambiguous. */ 224 CBS cbs, body; 225 struct hm_header_st msg_hdr; 226 CBS_init(&cbs, rr->data, rr->length); 227 if (!dtls1_parse_fragment(&cbs, &msg_hdr, &body)) { 228 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); 229 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HANDSHAKE_RECORD); 230 return -1; 231 } 232 233 if (msg_hdr.type == SSL3_MT_FINISHED && 234 msg_hdr.seq == ssl->d1->handshake_read_seq - 1) { 235 if (msg_hdr.frag_off == 0) { 236 /* Retransmit our last flight of messages. If the peer sends the second 237 * Finished, they may not have received ours. Only do this for the 238 * first fragment, in case the Finished was fragmented. */ 239 if (dtls1_check_timeout_num(ssl) < 0) { 240 return -1; 241 } 242 243 dtls1_retransmit_outgoing_messages(ssl); 244 } 245 246 rr->length = 0; 247 goto again; 248 } 249 250 /* Otherwise, this is a pre-CCS handshake message from an unsupported 251 * renegotiation attempt. Fall through to the error path. */ 252 } 253 254 if (rr->type != SSL3_RT_APPLICATION_DATA) { 255 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); 256 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 257 return -1; 258 } 259 260 /* Discard empty records. */ 261 if (rr->length == 0) { 262 goto again; 263 } 264 265 if (len <= 0) { 266 return len; 267 } 268 269 if ((unsigned)len > rr->length) { 270 len = rr->length; 271 } 272 273 OPENSSL_memcpy(buf, rr->data, len); 274 if (!peek) { 275 /* TODO(davidben): Should the record be truncated instead? This is a 276 * datagram transport. See https://crbug.com/boringssl/65. */ 277 rr->length -= len; 278 rr->data += len; 279 if (rr->length == 0) { 280 /* The record has been consumed, so we may now clear the buffer. */ 281 ssl_read_buffer_discard(ssl); 282 } 283 } 284 285 return len; 286 } 287 288 int dtls1_read_change_cipher_spec(SSL *ssl) { 289 SSL3_RECORD *rr = &ssl->s3->rrec; 290 291 again: 292 if (rr->length == 0) { 293 int ret = dtls1_get_record(ssl); 294 if (ret <= 0) { 295 return ret; 296 } 297 } 298 299 /* Drop handshake records silently. The epochs match, so this must be a 300 * retransmit of a message we already received. */ 301 if (rr->type == SSL3_RT_HANDSHAKE) { 302 rr->length = 0; 303 goto again; 304 } 305 306 /* Other record types are illegal in this epoch. Note all application data 307 * records come in the encrypted epoch. */ 308 if (rr->type != SSL3_RT_CHANGE_CIPHER_SPEC) { 309 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE); 310 OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD); 311 return -1; 312 } 313 314 if (rr->length != 1 || rr->data[0] != SSL3_MT_CCS) { 315 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_CHANGE_CIPHER_SPEC); 316 ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); 317 return -1; 318 } 319 320 ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_CHANGE_CIPHER_SPEC, rr->data, 321 rr->length); 322 323 rr->length = 0; 324 ssl_read_buffer_discard(ssl); 325 return 1; 326 } 327 328 void dtls1_read_close_notify(SSL *ssl) { 329 /* Bidirectional shutdown doesn't make sense for an unordered transport. DTLS 330 * alerts also aren't delivered reliably, so we may even time out because the 331 * peer never received our close_notify. Report to the caller that the channel 332 * has fully shut down. */ 333 if (ssl->s3->recv_shutdown == ssl_shutdown_none) { 334 ssl->s3->recv_shutdown = ssl_shutdown_close_notify; 335 } 336 } 337 338 int dtls1_write_app_data(SSL *ssl, const uint8_t *buf, int len) { 339 assert(!SSL_in_init(ssl)); 340 341 if (len > SSL3_RT_MAX_PLAIN_LENGTH) { 342 OPENSSL_PUT_ERROR(SSL, SSL_R_DTLS_MESSAGE_TOO_BIG); 343 return -1; 344 } 345 346 if (len < 0) { 347 OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_LENGTH); 348 return -1; 349 } 350 351 if (len == 0) { 352 return 0; 353 } 354 355 int ret = dtls1_write_record(ssl, SSL3_RT_APPLICATION_DATA, buf, (size_t)len, 356 dtls1_use_current_epoch); 357 if (ret <= 0) { 358 return ret; 359 } 360 return len; 361 } 362 363 int dtls1_write_record(SSL *ssl, int type, const uint8_t *buf, size_t len, 364 enum dtls1_use_epoch_t use_epoch) { 365 assert(len <= SSL3_RT_MAX_PLAIN_LENGTH); 366 /* There should never be a pending write buffer in DTLS. One can't write half 367 * a datagram, so the write buffer is always dropped in 368 * |ssl_write_buffer_flush|. */ 369 assert(!ssl_write_buffer_is_pending(ssl)); 370 371 if (len > SSL3_RT_MAX_PLAIN_LENGTH) { 372 OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); 373 return -1; 374 } 375 376 size_t max_out = len + SSL_max_seal_overhead(ssl); 377 uint8_t *out; 378 size_t ciphertext_len; 379 if (!ssl_write_buffer_init(ssl, &out, max_out) || 380 !dtls_seal_record(ssl, out, &ciphertext_len, max_out, type, buf, len, 381 use_epoch)) { 382 ssl_write_buffer_clear(ssl); 383 return -1; 384 } 385 ssl_write_buffer_set_len(ssl, ciphertext_len); 386 387 int ret = ssl_write_buffer_flush(ssl); 388 if (ret <= 0) { 389 return ret; 390 } 391 return 1; 392 } 393 394 int dtls1_dispatch_alert(SSL *ssl) { 395 int ret = dtls1_write_record(ssl, SSL3_RT_ALERT, &ssl->s3->send_alert[0], 2, 396 dtls1_use_current_epoch); 397 if (ret <= 0) { 398 return ret; 399 } 400 ssl->s3->alert_dispatch = 0; 401 402 /* If the alert is fatal, flush the BIO now. */ 403 if (ssl->s3->send_alert[0] == SSL3_AL_FATAL) { 404 BIO_flush(ssl->wbio); 405 } 406 407 ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_ALERT, ssl->s3->send_alert, 408 2); 409 410 int alert = (ssl->s3->send_alert[0] << 8) | ssl->s3->send_alert[1]; 411 ssl_do_info_callback(ssl, SSL_CB_WRITE_ALERT, alert); 412 413 return 1; 414 } 415
