1 /* 2 * Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the OpenSSL license (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include "internal/cryptlib.h" 11 #include <openssl/rand.h> 12 #include "../ssl_locl.h" 13 #include "statem_locl.h" 14 #include <assert.h> 15 16 /* 17 * This file implements the SSL/TLS/DTLS state machines. 18 * 19 * There are two primary state machines: 20 * 21 * 1) Message flow state machine 22 * 2) Handshake state machine 23 * 24 * The Message flow state machine controls the reading and sending of messages 25 * including handling of non-blocking IO events, flushing of the underlying 26 * write BIO, handling unexpected messages, etc. It is itself broken into two 27 * separate sub-state machines which control reading and writing respectively. 28 * 29 * The Handshake state machine keeps track of the current SSL/TLS handshake 30 * state. Transitions of the handshake state are the result of events that 31 * occur within the Message flow state machine. 32 * 33 * Overall it looks like this: 34 * 35 * --------------------------------------------- ------------------- 36 * | | | | 37 * | Message flow state machine | | | 38 * | | | | 39 * | -------------------- -------------------- | Transition | Handshake state | 40 * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event | machine | 41 * | | sub-state | | sub-state | |----------->| | 42 * | | machine for | | machine for | | | | 43 * | | reading messages | | writing messages | | | | 44 * | -------------------- -------------------- | | | 45 * | | | | 46 * --------------------------------------------- ------------------- 47 * 48 */ 49 50 /* Sub state machine return values */ 51 typedef enum { 52 /* Something bad happened or NBIO */ 53 SUB_STATE_ERROR, 54 /* Sub state finished go to the next sub state */ 55 SUB_STATE_FINISHED, 56 /* Sub state finished and handshake was completed */ 57 SUB_STATE_END_HANDSHAKE 58 } SUB_STATE_RETURN; 59 60 static int state_machine(SSL *s, int server); 61 static void init_read_state_machine(SSL *s); 62 static SUB_STATE_RETURN read_state_machine(SSL *s); 63 static void init_write_state_machine(SSL *s); 64 static SUB_STATE_RETURN write_state_machine(SSL *s); 65 66 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl) 67 { 68 return ssl->statem.hand_state; 69 } 70 71 int SSL_in_init(const SSL *s) 72 { 73 return s->statem.in_init; 74 } 75 76 int SSL_is_init_finished(const SSL *s) 77 { 78 return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK); 79 } 80 81 int SSL_in_before(const SSL *s) 82 { 83 /* 84 * Historically being "in before" meant before anything had happened. In the 85 * current code though we remain in the "before" state for a while after we 86 * have started the handshake process (e.g. as a server waiting for the 87 * first message to arrive). There "in before" is taken to mean "in before" 88 * and not started any handshake process yet. 89 */ 90 return (s->statem.hand_state == TLS_ST_BEFORE) 91 && (s->statem.state == MSG_FLOW_UNINITED); 92 } 93 94 /* 95 * Clear the state machine state and reset back to MSG_FLOW_UNINITED 96 */ 97 void ossl_statem_clear(SSL *s) 98 { 99 s->statem.state = MSG_FLOW_UNINITED; 100 s->statem.hand_state = TLS_ST_BEFORE; 101 s->statem.in_init = 1; 102 s->statem.no_cert_verify = 0; 103 } 104 105 /* 106 * Set the state machine up ready for a renegotiation handshake 107 */ 108 void ossl_statem_set_renegotiate(SSL *s) 109 { 110 s->statem.in_init = 1; 111 s->statem.request_state = TLS_ST_SW_HELLO_REQ; 112 } 113 114 /* 115 * Put the state machine into an error state and send an alert if appropriate. 116 * This is a permanent error for the current connection. 117 */ 118 void ossl_statem_fatal(SSL *s, int al, int func, int reason, const char *file, 119 int line) 120 { 121 ERR_put_error(ERR_LIB_SSL, func, reason, file, line); 122 /* We shouldn't call SSLfatal() twice. Once is enough */ 123 if (s->statem.in_init && s->statem.state == MSG_FLOW_ERROR) 124 return; 125 s->statem.in_init = 1; 126 s->statem.state = MSG_FLOW_ERROR; 127 if (al != SSL_AD_NO_ALERT 128 && s->statem.enc_write_state != ENC_WRITE_STATE_INVALID) 129 ssl3_send_alert(s, SSL3_AL_FATAL, al); 130 } 131 132 /* 133 * This macro should only be called if we are already expecting to be in 134 * a fatal error state. We verify that we are, and set it if not (this would 135 * indicate a bug). 136 */ 137 #define check_fatal(s, f) \ 138 do { \ 139 if (!ossl_assert((s)->statem.in_init \ 140 && (s)->statem.state == MSG_FLOW_ERROR)) \ 141 SSLfatal(s, SSL_AD_INTERNAL_ERROR, (f), \ 142 SSL_R_MISSING_FATAL); \ 143 } while (0) 144 145 /* 146 * Discover whether the current connection is in the error state. 147 * 148 * Valid return values are: 149 * 1: Yes 150 * 0: No 151 */ 152 int ossl_statem_in_error(const SSL *s) 153 { 154 if (s->statem.state == MSG_FLOW_ERROR) 155 return 1; 156 157 return 0; 158 } 159 160 void ossl_statem_set_in_init(SSL *s, int init) 161 { 162 s->statem.in_init = init; 163 } 164 165 int ossl_statem_get_in_handshake(SSL *s) 166 { 167 return s->statem.in_handshake; 168 } 169 170 void ossl_statem_set_in_handshake(SSL *s, int inhand) 171 { 172 if (inhand) 173 s->statem.in_handshake++; 174 else 175 s->statem.in_handshake--; 176 } 177 178 /* Are we in a sensible state to skip over unreadable early data? */ 179 int ossl_statem_skip_early_data(SSL *s) 180 { 181 if (s->ext.early_data != SSL_EARLY_DATA_REJECTED) 182 return 0; 183 184 if (!s->server 185 || s->statem.hand_state != TLS_ST_EARLY_DATA 186 || s->hello_retry_request == SSL_HRR_COMPLETE) 187 return 0; 188 189 return 1; 190 } 191 192 /* 193 * Called when we are in SSL_read*(), SSL_write*(), or SSL_accept() 194 * /SSL_connect()/SSL_do_handshake(). Used to test whether we are in an early 195 * data state and whether we should attempt to move the handshake on if so. 196 * |sending| is 1 if we are attempting to send data (SSL_write*()), 0 if we are 197 * attempting to read data (SSL_read*()), or -1 if we are in SSL_do_handshake() 198 * or similar. 199 */ 200 void ossl_statem_check_finish_init(SSL *s, int sending) 201 { 202 if (sending == -1) { 203 if (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END 204 || s->statem.hand_state == TLS_ST_EARLY_DATA) { 205 ossl_statem_set_in_init(s, 1); 206 if (s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) { 207 /* 208 * SSL_connect() or SSL_do_handshake() has been called directly. 209 * We don't allow any more writing of early data. 210 */ 211 s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING; 212 } 213 } 214 } else if (!s->server) { 215 if ((sending && (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END 216 || s->statem.hand_state == TLS_ST_EARLY_DATA) 217 && s->early_data_state != SSL_EARLY_DATA_WRITING) 218 || (!sending && s->statem.hand_state == TLS_ST_EARLY_DATA)) { 219 ossl_statem_set_in_init(s, 1); 220 /* 221 * SSL_write() has been called directly. We don't allow any more 222 * writing of early data. 223 */ 224 if (sending && s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) 225 s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING; 226 } 227 } else { 228 if (s->early_data_state == SSL_EARLY_DATA_FINISHED_READING 229 && s->statem.hand_state == TLS_ST_EARLY_DATA) 230 ossl_statem_set_in_init(s, 1); 231 } 232 } 233 234 void ossl_statem_set_hello_verify_done(SSL *s) 235 { 236 s->statem.state = MSG_FLOW_UNINITED; 237 s->statem.in_init = 1; 238 /* 239 * This will get reset (briefly) back to TLS_ST_BEFORE when we enter 240 * state_machine() because |state| is MSG_FLOW_UNINITED, but until then any 241 * calls to SSL_in_before() will return false. Also calls to 242 * SSL_state_string() and SSL_state_string_long() will return something 243 * sensible. 244 */ 245 s->statem.hand_state = TLS_ST_SR_CLNT_HELLO; 246 } 247 248 int ossl_statem_connect(SSL *s) 249 { 250 return state_machine(s, 0); 251 } 252 253 int ossl_statem_accept(SSL *s) 254 { 255 return state_machine(s, 1); 256 } 257 258 typedef void (*info_cb) (const SSL *, int, int); 259 260 static info_cb get_callback(SSL *s) 261 { 262 if (s->info_callback != NULL) 263 return s->info_callback; 264 else if (s->ctx->info_callback != NULL) 265 return s->ctx->info_callback; 266 267 return NULL; 268 } 269 270 /* 271 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or 272 * MSG_FLOW_FINISHED state and finish in MSG_FLOW_FINISHED. Valid states and 273 * transitions are as follows: 274 * 275 * MSG_FLOW_UNINITED MSG_FLOW_FINISHED 276 * | | 277 * +-----------------------+ 278 * v 279 * MSG_FLOW_WRITING <---> MSG_FLOW_READING 280 * | 281 * V 282 * MSG_FLOW_FINISHED 283 * | 284 * V 285 * [SUCCESS] 286 * 287 * We may exit at any point due to an error or NBIO event. If an NBIO event 288 * occurs then we restart at the point we left off when we are recalled. 289 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them. 290 * 291 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move 292 * into that state at any point in the event that an irrecoverable error occurs. 293 * 294 * Valid return values are: 295 * 1: Success 296 * <=0: NBIO or error 297 */ 298 static int state_machine(SSL *s, int server) 299 { 300 BUF_MEM *buf = NULL; 301 void (*cb) (const SSL *ssl, int type, int val) = NULL; 302 OSSL_STATEM *st = &s->statem; 303 int ret = -1; 304 int ssret; 305 306 if (st->state == MSG_FLOW_ERROR) { 307 /* Shouldn't have been called if we're already in the error state */ 308 return -1; 309 } 310 311 ERR_clear_error(); 312 clear_sys_error(); 313 314 cb = get_callback(s); 315 316 st->in_handshake++; 317 if (!SSL_in_init(s) || SSL_in_before(s)) { 318 /* 319 * If we are stateless then we already called SSL_clear() - don't do 320 * it again and clear the STATELESS flag itself. 321 */ 322 if ((s->s3->flags & TLS1_FLAGS_STATELESS) == 0 && !SSL_clear(s)) 323 return -1; 324 } 325 #ifndef OPENSSL_NO_SCTP 326 if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) { 327 /* 328 * Notify SCTP BIO socket to enter handshake mode and prevent stream 329 * identifier other than 0. 330 */ 331 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE, 332 st->in_handshake, NULL); 333 } 334 #endif 335 336 /* Initialise state machine */ 337 if (st->state == MSG_FLOW_UNINITED 338 || st->state == MSG_FLOW_FINISHED) { 339 if (st->state == MSG_FLOW_UNINITED) { 340 st->hand_state = TLS_ST_BEFORE; 341 st->request_state = TLS_ST_BEFORE; 342 } 343 344 s->server = server; 345 if (cb != NULL) 346 cb(s, SSL_CB_HANDSHAKE_START, 1); 347 348 /* 349 * Fatal errors in this block don't send an alert because we have 350 * failed to even initialise properly. Sending an alert is probably 351 * doomed to failure. 352 */ 353 354 if (SSL_IS_DTLS(s)) { 355 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) && 356 (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) { 357 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 358 ERR_R_INTERNAL_ERROR); 359 goto end; 360 } 361 } else { 362 if ((s->version >> 8) != SSL3_VERSION_MAJOR) { 363 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 364 ERR_R_INTERNAL_ERROR); 365 goto end; 366 } 367 } 368 369 if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) { 370 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 371 ERR_R_INTERNAL_ERROR); 372 goto end; 373 } 374 375 if (s->init_buf == NULL) { 376 if ((buf = BUF_MEM_new()) == NULL) { 377 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 378 ERR_R_INTERNAL_ERROR); 379 goto end; 380 } 381 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) { 382 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 383 ERR_R_INTERNAL_ERROR); 384 goto end; 385 } 386 s->init_buf = buf; 387 buf = NULL; 388 } 389 390 if (!ssl3_setup_buffers(s)) { 391 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 392 ERR_R_INTERNAL_ERROR); 393 goto end; 394 } 395 s->init_num = 0; 396 397 /* 398 * Should have been reset by tls_process_finished, too. 399 */ 400 s->s3->change_cipher_spec = 0; 401 402 /* 403 * Ok, we now need to push on a buffering BIO ...but not with 404 * SCTP 405 */ 406 #ifndef OPENSSL_NO_SCTP 407 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s))) 408 #endif 409 if (!ssl_init_wbio_buffer(s)) { 410 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE, 411 ERR_R_INTERNAL_ERROR); 412 goto end; 413 } 414 415 if ((SSL_in_before(s)) 416 || s->renegotiate) { 417 if (!tls_setup_handshake(s)) { 418 /* SSLfatal() already called */ 419 goto end; 420 } 421 422 if (SSL_IS_FIRST_HANDSHAKE(s)) 423 st->read_state_first_init = 1; 424 } 425 426 st->state = MSG_FLOW_WRITING; 427 init_write_state_machine(s); 428 } 429 430 while (st->state != MSG_FLOW_FINISHED) { 431 if (st->state == MSG_FLOW_READING) { 432 ssret = read_state_machine(s); 433 if (ssret == SUB_STATE_FINISHED) { 434 st->state = MSG_FLOW_WRITING; 435 init_write_state_machine(s); 436 } else { 437 /* NBIO or error */ 438 goto end; 439 } 440 } else if (st->state == MSG_FLOW_WRITING) { 441 ssret = write_state_machine(s); 442 if (ssret == SUB_STATE_FINISHED) { 443 st->state = MSG_FLOW_READING; 444 init_read_state_machine(s); 445 } else if (ssret == SUB_STATE_END_HANDSHAKE) { 446 st->state = MSG_FLOW_FINISHED; 447 } else { 448 /* NBIO or error */ 449 goto end; 450 } 451 } else { 452 /* Error */ 453 check_fatal(s, SSL_F_STATE_MACHINE); 454 SSLerr(SSL_F_STATE_MACHINE, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); 455 goto end; 456 } 457 } 458 459 ret = 1; 460 461 end: 462 st->in_handshake--; 463 464 #ifndef OPENSSL_NO_SCTP 465 if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) { 466 /* 467 * Notify SCTP BIO socket to leave handshake mode and allow stream 468 * identifier other than 0. 469 */ 470 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE, 471 st->in_handshake, NULL); 472 } 473 #endif 474 475 BUF_MEM_free(buf); 476 if (cb != NULL) { 477 if (server) 478 cb(s, SSL_CB_ACCEPT_EXIT, ret); 479 else 480 cb(s, SSL_CB_CONNECT_EXIT, ret); 481 } 482 return ret; 483 } 484 485 /* 486 * Initialise the MSG_FLOW_READING sub-state machine 487 */ 488 static void init_read_state_machine(SSL *s) 489 { 490 OSSL_STATEM *st = &s->statem; 491 492 st->read_state = READ_STATE_HEADER; 493 } 494 495 static int grow_init_buf(SSL *s, size_t size) { 496 497 size_t msg_offset = (char *)s->init_msg - s->init_buf->data; 498 499 if (!BUF_MEM_grow_clean(s->init_buf, (int)size)) 500 return 0; 501 502 if (size < msg_offset) 503 return 0; 504 505 s->init_msg = s->init_buf->data + msg_offset; 506 507 return 1; 508 } 509 510 /* 511 * This function implements the sub-state machine when the message flow is in 512 * MSG_FLOW_READING. The valid sub-states and transitions are: 513 * 514 * READ_STATE_HEADER <--+<-------------+ 515 * | | | 516 * v | | 517 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS 518 * | | 519 * +----------------------------+ 520 * v 521 * [SUB_STATE_FINISHED] 522 * 523 * READ_STATE_HEADER has the responsibility for reading in the message header 524 * and transitioning the state of the handshake state machine. 525 * 526 * READ_STATE_BODY reads in the rest of the message and then subsequently 527 * processes it. 528 * 529 * READ_STATE_POST_PROCESS is an optional step that may occur if some post 530 * processing activity performed on the message may block. 531 * 532 * Any of the above states could result in an NBIO event occurring in which case 533 * control returns to the calling application. When this function is recalled we 534 * will resume in the same state where we left off. 535 */ 536 static SUB_STATE_RETURN read_state_machine(SSL *s) 537 { 538 OSSL_STATEM *st = &s->statem; 539 int ret, mt; 540 size_t len = 0; 541 int (*transition) (SSL *s, int mt); 542 PACKET pkt; 543 MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt); 544 WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst); 545 size_t (*max_message_size) (SSL *s); 546 void (*cb) (const SSL *ssl, int type, int val) = NULL; 547 548 cb = get_callback(s); 549 550 if (s->server) { 551 transition = ossl_statem_server_read_transition; 552 process_message = ossl_statem_server_process_message; 553 max_message_size = ossl_statem_server_max_message_size; 554 post_process_message = ossl_statem_server_post_process_message; 555 } else { 556 transition = ossl_statem_client_read_transition; 557 process_message = ossl_statem_client_process_message; 558 max_message_size = ossl_statem_client_max_message_size; 559 post_process_message = ossl_statem_client_post_process_message; 560 } 561 562 if (st->read_state_first_init) { 563 s->first_packet = 1; 564 st->read_state_first_init = 0; 565 } 566 567 while (1) { 568 switch (st->read_state) { 569 case READ_STATE_HEADER: 570 /* Get the state the peer wants to move to */ 571 if (SSL_IS_DTLS(s)) { 572 /* 573 * In DTLS we get the whole message in one go - header and body 574 */ 575 ret = dtls_get_message(s, &mt, &len); 576 } else { 577 ret = tls_get_message_header(s, &mt); 578 } 579 580 if (ret == 0) { 581 /* Could be non-blocking IO */ 582 return SUB_STATE_ERROR; 583 } 584 585 if (cb != NULL) { 586 /* Notify callback of an impending state change */ 587 if (s->server) 588 cb(s, SSL_CB_ACCEPT_LOOP, 1); 589 else 590 cb(s, SSL_CB_CONNECT_LOOP, 1); 591 } 592 /* 593 * Validate that we are allowed to move to the new state and move 594 * to that state if so 595 */ 596 if (!transition(s, mt)) 597 return SUB_STATE_ERROR; 598 599 if (s->s3->tmp.message_size > max_message_size(s)) { 600 SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_READ_STATE_MACHINE, 601 SSL_R_EXCESSIVE_MESSAGE_SIZE); 602 return SUB_STATE_ERROR; 603 } 604 605 /* dtls_get_message already did this */ 606 if (!SSL_IS_DTLS(s) 607 && s->s3->tmp.message_size > 0 608 && !grow_init_buf(s, s->s3->tmp.message_size 609 + SSL3_HM_HEADER_LENGTH)) { 610 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE, 611 ERR_R_BUF_LIB); 612 return SUB_STATE_ERROR; 613 } 614 615 st->read_state = READ_STATE_BODY; 616 /* Fall through */ 617 618 case READ_STATE_BODY: 619 if (!SSL_IS_DTLS(s)) { 620 /* We already got this above for DTLS */ 621 ret = tls_get_message_body(s, &len); 622 if (ret == 0) { 623 /* Could be non-blocking IO */ 624 return SUB_STATE_ERROR; 625 } 626 } 627 628 s->first_packet = 0; 629 if (!PACKET_buf_init(&pkt, s->init_msg, len)) { 630 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE, 631 ERR_R_INTERNAL_ERROR); 632 return SUB_STATE_ERROR; 633 } 634 ret = process_message(s, &pkt); 635 636 /* Discard the packet data */ 637 s->init_num = 0; 638 639 switch (ret) { 640 case MSG_PROCESS_ERROR: 641 check_fatal(s, SSL_F_READ_STATE_MACHINE); 642 return SUB_STATE_ERROR; 643 644 case MSG_PROCESS_FINISHED_READING: 645 if (SSL_IS_DTLS(s)) { 646 dtls1_stop_timer(s); 647 } 648 return SUB_STATE_FINISHED; 649 650 case MSG_PROCESS_CONTINUE_PROCESSING: 651 st->read_state = READ_STATE_POST_PROCESS; 652 st->read_state_work = WORK_MORE_A; 653 break; 654 655 default: 656 st->read_state = READ_STATE_HEADER; 657 break; 658 } 659 break; 660 661 case READ_STATE_POST_PROCESS: 662 st->read_state_work = post_process_message(s, st->read_state_work); 663 switch (st->read_state_work) { 664 case WORK_ERROR: 665 check_fatal(s, SSL_F_READ_STATE_MACHINE); 666 /* Fall through */ 667 case WORK_MORE_A: 668 case WORK_MORE_B: 669 case WORK_MORE_C: 670 return SUB_STATE_ERROR; 671 672 case WORK_FINISHED_CONTINUE: 673 st->read_state = READ_STATE_HEADER; 674 break; 675 676 case WORK_FINISHED_STOP: 677 if (SSL_IS_DTLS(s)) { 678 dtls1_stop_timer(s); 679 } 680 return SUB_STATE_FINISHED; 681 } 682 break; 683 684 default: 685 /* Shouldn't happen */ 686 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE, 687 ERR_R_INTERNAL_ERROR); 688 return SUB_STATE_ERROR; 689 } 690 } 691 } 692 693 /* 694 * Send a previously constructed message to the peer. 695 */ 696 static int statem_do_write(SSL *s) 697 { 698 OSSL_STATEM *st = &s->statem; 699 700 if (st->hand_state == TLS_ST_CW_CHANGE 701 || st->hand_state == TLS_ST_SW_CHANGE) { 702 if (SSL_IS_DTLS(s)) 703 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC); 704 else 705 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC); 706 } else { 707 return ssl_do_write(s); 708 } 709 } 710 711 /* 712 * Initialise the MSG_FLOW_WRITING sub-state machine 713 */ 714 static void init_write_state_machine(SSL *s) 715 { 716 OSSL_STATEM *st = &s->statem; 717 718 st->write_state = WRITE_STATE_TRANSITION; 719 } 720 721 /* 722 * This function implements the sub-state machine when the message flow is in 723 * MSG_FLOW_WRITING. The valid sub-states and transitions are: 724 * 725 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED] 726 * | | 727 * | v 728 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE] 729 * | | 730 * | v 731 * | WRITE_STATE_SEND 732 * | | 733 * | v 734 * | WRITE_STATE_POST_WORK 735 * | | 736 * +-------------+ 737 * 738 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine 739 740 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later 741 * sending of the message. This could result in an NBIO event occurring in 742 * which case control returns to the calling application. When this function 743 * is recalled we will resume in the same state where we left off. 744 * 745 * WRITE_STATE_SEND sends the message and performs any work to be done after 746 * sending. 747 * 748 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the 749 * message has been completed. As for WRITE_STATE_PRE_WORK this could also 750 * result in an NBIO event. 751 */ 752 static SUB_STATE_RETURN write_state_machine(SSL *s) 753 { 754 OSSL_STATEM *st = &s->statem; 755 int ret; 756 WRITE_TRAN(*transition) (SSL *s); 757 WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst); 758 WORK_STATE(*post_work) (SSL *s, WORK_STATE wst); 759 int (*get_construct_message_f) (SSL *s, WPACKET *pkt, 760 int (**confunc) (SSL *s, WPACKET *pkt), 761 int *mt); 762 void (*cb) (const SSL *ssl, int type, int val) = NULL; 763 int (*confunc) (SSL *s, WPACKET *pkt); 764 int mt; 765 WPACKET pkt; 766 767 cb = get_callback(s); 768 769 if (s->server) { 770 transition = ossl_statem_server_write_transition; 771 pre_work = ossl_statem_server_pre_work; 772 post_work = ossl_statem_server_post_work; 773 get_construct_message_f = ossl_statem_server_construct_message; 774 } else { 775 transition = ossl_statem_client_write_transition; 776 pre_work = ossl_statem_client_pre_work; 777 post_work = ossl_statem_client_post_work; 778 get_construct_message_f = ossl_statem_client_construct_message; 779 } 780 781 while (1) { 782 switch (st->write_state) { 783 case WRITE_STATE_TRANSITION: 784 if (cb != NULL) { 785 /* Notify callback of an impending state change */ 786 if (s->server) 787 cb(s, SSL_CB_ACCEPT_LOOP, 1); 788 else 789 cb(s, SSL_CB_CONNECT_LOOP, 1); 790 } 791 switch (transition(s)) { 792 case WRITE_TRAN_CONTINUE: 793 st->write_state = WRITE_STATE_PRE_WORK; 794 st->write_state_work = WORK_MORE_A; 795 break; 796 797 case WRITE_TRAN_FINISHED: 798 return SUB_STATE_FINISHED; 799 break; 800 801 case WRITE_TRAN_ERROR: 802 check_fatal(s, SSL_F_WRITE_STATE_MACHINE); 803 return SUB_STATE_ERROR; 804 } 805 break; 806 807 case WRITE_STATE_PRE_WORK: 808 switch (st->write_state_work = pre_work(s, st->write_state_work)) { 809 case WORK_ERROR: 810 check_fatal(s, SSL_F_WRITE_STATE_MACHINE); 811 /* Fall through */ 812 case WORK_MORE_A: 813 case WORK_MORE_B: 814 case WORK_MORE_C: 815 return SUB_STATE_ERROR; 816 817 case WORK_FINISHED_CONTINUE: 818 st->write_state = WRITE_STATE_SEND; 819 break; 820 821 case WORK_FINISHED_STOP: 822 return SUB_STATE_END_HANDSHAKE; 823 } 824 if (!get_construct_message_f(s, &pkt, &confunc, &mt)) { 825 /* SSLfatal() already called */ 826 return SUB_STATE_ERROR; 827 } 828 if (mt == SSL3_MT_DUMMY) { 829 /* Skip construction and sending. This isn't a "real" state */ 830 st->write_state = WRITE_STATE_POST_WORK; 831 st->write_state_work = WORK_MORE_A; 832 break; 833 } 834 if (!WPACKET_init(&pkt, s->init_buf) 835 || !ssl_set_handshake_header(s, &pkt, mt)) { 836 WPACKET_cleanup(&pkt); 837 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE, 838 ERR_R_INTERNAL_ERROR); 839 return SUB_STATE_ERROR; 840 } 841 if (confunc != NULL && !confunc(s, &pkt)) { 842 WPACKET_cleanup(&pkt); 843 check_fatal(s, SSL_F_WRITE_STATE_MACHINE); 844 return SUB_STATE_ERROR; 845 } 846 if (!ssl_close_construct_packet(s, &pkt, mt) 847 || !WPACKET_finish(&pkt)) { 848 WPACKET_cleanup(&pkt); 849 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE, 850 ERR_R_INTERNAL_ERROR); 851 return SUB_STATE_ERROR; 852 } 853 854 /* Fall through */ 855 856 case WRITE_STATE_SEND: 857 if (SSL_IS_DTLS(s) && st->use_timer) { 858 dtls1_start_timer(s); 859 } 860 ret = statem_do_write(s); 861 if (ret <= 0) { 862 return SUB_STATE_ERROR; 863 } 864 st->write_state = WRITE_STATE_POST_WORK; 865 st->write_state_work = WORK_MORE_A; 866 /* Fall through */ 867 868 case WRITE_STATE_POST_WORK: 869 switch (st->write_state_work = post_work(s, st->write_state_work)) { 870 case WORK_ERROR: 871 check_fatal(s, SSL_F_WRITE_STATE_MACHINE); 872 /* Fall through */ 873 case WORK_MORE_A: 874 case WORK_MORE_B: 875 case WORK_MORE_C: 876 return SUB_STATE_ERROR; 877 878 case WORK_FINISHED_CONTINUE: 879 st->write_state = WRITE_STATE_TRANSITION; 880 break; 881 882 case WORK_FINISHED_STOP: 883 return SUB_STATE_END_HANDSHAKE; 884 } 885 break; 886 887 default: 888 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE, 889 ERR_R_INTERNAL_ERROR); 890 return SUB_STATE_ERROR; 891 } 892 } 893 } 894 895 /* 896 * Flush the write BIO 897 */ 898 int statem_flush(SSL *s) 899 { 900 s->rwstate = SSL_WRITING; 901 if (BIO_flush(s->wbio) <= 0) { 902 return 0; 903 } 904 s->rwstate = SSL_NOTHING; 905 906 return 1; 907 } 908 909 /* 910 * Called by the record layer to determine whether application data is 911 * allowed to be received in the current handshake state or not. 912 * 913 * Return values are: 914 * 1: Yes (application data allowed) 915 * 0: No (application data not allowed) 916 */ 917 int ossl_statem_app_data_allowed(SSL *s) 918 { 919 OSSL_STATEM *st = &s->statem; 920 921 if (st->state == MSG_FLOW_UNINITED) 922 return 0; 923 924 if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0)) 925 return 0; 926 927 if (s->server) { 928 /* 929 * If we're a server and we haven't got as far as writing our 930 * ServerHello yet then we allow app data 931 */ 932 if (st->hand_state == TLS_ST_BEFORE 933 || st->hand_state == TLS_ST_SR_CLNT_HELLO) 934 return 1; 935 } else { 936 /* 937 * If we're a client and we haven't read the ServerHello yet then we 938 * allow app data 939 */ 940 if (st->hand_state == TLS_ST_CW_CLNT_HELLO) 941 return 1; 942 } 943 944 return 0; 945 } 946 947 /* 948 * This function returns 1 if TLS exporter is ready to export keying 949 * material, or 0 if otherwise. 950 */ 951 int ossl_statem_export_allowed(SSL *s) 952 { 953 return s->s3->previous_server_finished_len != 0 954 && s->statem.hand_state != TLS_ST_SW_FINISHED; 955 } 956 957 /* 958 * Return 1 if early TLS exporter is ready to export keying material, 959 * or 0 if otherwise. 960 */ 961 int ossl_statem_export_early_allowed(SSL *s) 962 { 963 /* 964 * The early exporter secret is only present on the server if we 965 * have accepted early_data. It is present on the client as long 966 * as we have sent early_data. 967 */ 968 return s->ext.early_data == SSL_EARLY_DATA_ACCEPTED 969 || (!s->server && s->ext.early_data != SSL_EARLY_DATA_NOT_SENT); 970 } 971