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