1 /*
2 * Copyright 2015-2019 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_local.h"
13 #include "statem_local.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
SSL_get_state(const SSL * ssl)66 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
67 {
68 return ssl->statem.hand_state;
69 }
70
SSL_in_init(const SSL * s)71 int SSL_in_init(const SSL *s)
72 {
73 return s->statem.in_init;
74 }
75
SSL_is_init_finished(const SSL * s)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
SSL_in_before(const SSL * s)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 */
ossl_statem_clear(SSL * s)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 */
ossl_statem_set_renegotiate(SSL * s)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 */
ossl_statem_fatal(SSL * s,int al,int func,int reason,const char * file,int line)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 */
ossl_statem_in_error(const SSL * s)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
ossl_statem_set_in_init(SSL * s,int init)160 void ossl_statem_set_in_init(SSL *s, int init)
161 {
162 s->statem.in_init = init;
163 }
164
ossl_statem_get_in_handshake(SSL * s)165 int ossl_statem_get_in_handshake(SSL *s)
166 {
167 return s->statem.in_handshake;
168 }
169
ossl_statem_set_in_handshake(SSL * s,int inhand)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? */
ossl_statem_skip_early_data(SSL * s)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 */
ossl_statem_check_finish_init(SSL * s,int sending)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
ossl_statem_set_hello_verify_done(SSL * s)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
ossl_statem_connect(SSL * s)248 int ossl_statem_connect(SSL *s)
249 {
250 return state_machine(s, 0);
251 }
252
ossl_statem_accept(SSL * s)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
get_callback(SSL * s)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 */
state_machine(SSL * s,int server)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 if (SSL_IS_FIRST_HANDSHAKE(s) || !SSL_IS_TLS13(s))
347 cb(s, SSL_CB_HANDSHAKE_START, 1);
348 }
349
350 /*
351 * Fatal errors in this block don't send an alert because we have
352 * failed to even initialise properly. Sending an alert is probably
353 * doomed to failure.
354 */
355
356 if (SSL_IS_DTLS(s)) {
357 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
358 (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
359 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
360 ERR_R_INTERNAL_ERROR);
361 goto end;
362 }
363 } else {
364 if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
365 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
366 ERR_R_INTERNAL_ERROR);
367 goto end;
368 }
369 }
370
371 if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
372 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
373 ERR_R_INTERNAL_ERROR);
374 goto end;
375 }
376
377 if (s->init_buf == NULL) {
378 if ((buf = BUF_MEM_new()) == NULL) {
379 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
380 ERR_R_INTERNAL_ERROR);
381 goto end;
382 }
383 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
384 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
385 ERR_R_INTERNAL_ERROR);
386 goto end;
387 }
388 s->init_buf = buf;
389 buf = NULL;
390 }
391
392 if (!ssl3_setup_buffers(s)) {
393 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
394 ERR_R_INTERNAL_ERROR);
395 goto end;
396 }
397 s->init_num = 0;
398
399 /*
400 * Should have been reset by tls_process_finished, too.
401 */
402 s->s3->change_cipher_spec = 0;
403
404 /*
405 * Ok, we now need to push on a buffering BIO ...but not with
406 * SCTP
407 */
408 #ifndef OPENSSL_NO_SCTP
409 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
410 #endif
411 if (!ssl_init_wbio_buffer(s)) {
412 SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,
413 ERR_R_INTERNAL_ERROR);
414 goto end;
415 }
416
417 if ((SSL_in_before(s))
418 || s->renegotiate) {
419 if (!tls_setup_handshake(s)) {
420 /* SSLfatal() already called */
421 goto end;
422 }
423
424 if (SSL_IS_FIRST_HANDSHAKE(s))
425 st->read_state_first_init = 1;
426 }
427
428 st->state = MSG_FLOW_WRITING;
429 init_write_state_machine(s);
430 }
431
432 while (st->state != MSG_FLOW_FINISHED) {
433 if (st->state == MSG_FLOW_READING) {
434 ssret = read_state_machine(s);
435 if (ssret == SUB_STATE_FINISHED) {
436 st->state = MSG_FLOW_WRITING;
437 init_write_state_machine(s);
438 } else {
439 /* NBIO or error */
440 goto end;
441 }
442 } else if (st->state == MSG_FLOW_WRITING) {
443 ssret = write_state_machine(s);
444 if (ssret == SUB_STATE_FINISHED) {
445 st->state = MSG_FLOW_READING;
446 init_read_state_machine(s);
447 } else if (ssret == SUB_STATE_END_HANDSHAKE) {
448 st->state = MSG_FLOW_FINISHED;
449 } else {
450 /* NBIO or error */
451 goto end;
452 }
453 } else {
454 /* Error */
455 check_fatal(s, SSL_F_STATE_MACHINE);
456 SSLerr(SSL_F_STATE_MACHINE, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
457 goto end;
458 }
459 }
460
461 ret = 1;
462
463 end:
464 st->in_handshake--;
465
466 #ifndef OPENSSL_NO_SCTP
467 if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) {
468 /*
469 * Notify SCTP BIO socket to leave handshake mode and allow stream
470 * identifier other than 0.
471 */
472 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
473 st->in_handshake, NULL);
474 }
475 #endif
476
477 BUF_MEM_free(buf);
478 if (cb != NULL) {
479 if (server)
480 cb(s, SSL_CB_ACCEPT_EXIT, ret);
481 else
482 cb(s, SSL_CB_CONNECT_EXIT, ret);
483 }
484 return ret;
485 }
486
487 /*
488 * Initialise the MSG_FLOW_READING sub-state machine
489 */
init_read_state_machine(SSL * s)490 static void init_read_state_machine(SSL *s)
491 {
492 OSSL_STATEM *st = &s->statem;
493
494 st->read_state = READ_STATE_HEADER;
495 }
496
grow_init_buf(SSL * s,size_t size)497 static int grow_init_buf(SSL *s, size_t size) {
498
499 size_t msg_offset = (char *)s->init_msg - s->init_buf->data;
500
501 if (!BUF_MEM_grow_clean(s->init_buf, (int)size))
502 return 0;
503
504 if (size < msg_offset)
505 return 0;
506
507 s->init_msg = s->init_buf->data + msg_offset;
508
509 return 1;
510 }
511
512 /*
513 * This function implements the sub-state machine when the message flow is in
514 * MSG_FLOW_READING. The valid sub-states and transitions are:
515 *
516 * READ_STATE_HEADER <--+<-------------+
517 * | | |
518 * v | |
519 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
520 * | |
521 * +----------------------------+
522 * v
523 * [SUB_STATE_FINISHED]
524 *
525 * READ_STATE_HEADER has the responsibility for reading in the message header
526 * and transitioning the state of the handshake state machine.
527 *
528 * READ_STATE_BODY reads in the rest of the message and then subsequently
529 * processes it.
530 *
531 * READ_STATE_POST_PROCESS is an optional step that may occur if some post
532 * processing activity performed on the message may block.
533 *
534 * Any of the above states could result in an NBIO event occurring in which case
535 * control returns to the calling application. When this function is recalled we
536 * will resume in the same state where we left off.
537 */
read_state_machine(SSL * s)538 static SUB_STATE_RETURN read_state_machine(SSL *s)
539 {
540 OSSL_STATEM *st = &s->statem;
541 int ret, mt;
542 size_t len = 0;
543 int (*transition) (SSL *s, int mt);
544 PACKET pkt;
545 MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt);
546 WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst);
547 size_t (*max_message_size) (SSL *s);
548 void (*cb) (const SSL *ssl, int type, int val) = NULL;
549
550 cb = get_callback(s);
551
552 if (s->server) {
553 transition = ossl_statem_server_read_transition;
554 process_message = ossl_statem_server_process_message;
555 max_message_size = ossl_statem_server_max_message_size;
556 post_process_message = ossl_statem_server_post_process_message;
557 } else {
558 transition = ossl_statem_client_read_transition;
559 process_message = ossl_statem_client_process_message;
560 max_message_size = ossl_statem_client_max_message_size;
561 post_process_message = ossl_statem_client_post_process_message;
562 }
563
564 if (st->read_state_first_init) {
565 s->first_packet = 1;
566 st->read_state_first_init = 0;
567 }
568
569 while (1) {
570 switch (st->read_state) {
571 case READ_STATE_HEADER:
572 /* Get the state the peer wants to move to */
573 if (SSL_IS_DTLS(s)) {
574 /*
575 * In DTLS we get the whole message in one go - header and body
576 */
577 ret = dtls_get_message(s, &mt, &len);
578 } else {
579 ret = tls_get_message_header(s, &mt);
580 }
581
582 if (ret == 0) {
583 /* Could be non-blocking IO */
584 return SUB_STATE_ERROR;
585 }
586
587 if (cb != NULL) {
588 /* Notify callback of an impending state change */
589 if (s->server)
590 cb(s, SSL_CB_ACCEPT_LOOP, 1);
591 else
592 cb(s, SSL_CB_CONNECT_LOOP, 1);
593 }
594 /*
595 * Validate that we are allowed to move to the new state and move
596 * to that state if so
597 */
598 if (!transition(s, mt))
599 return SUB_STATE_ERROR;
600
601 if (s->s3->tmp.message_size > max_message_size(s)) {
602 SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_READ_STATE_MACHINE,
603 SSL_R_EXCESSIVE_MESSAGE_SIZE);
604 return SUB_STATE_ERROR;
605 }
606
607 /* dtls_get_message already did this */
608 if (!SSL_IS_DTLS(s)
609 && s->s3->tmp.message_size > 0
610 && !grow_init_buf(s, s->s3->tmp.message_size
611 + SSL3_HM_HEADER_LENGTH)) {
612 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,
613 ERR_R_BUF_LIB);
614 return SUB_STATE_ERROR;
615 }
616
617 st->read_state = READ_STATE_BODY;
618 /* Fall through */
619
620 case READ_STATE_BODY:
621 if (!SSL_IS_DTLS(s)) {
622 /* We already got this above for DTLS */
623 ret = tls_get_message_body(s, &len);
624 if (ret == 0) {
625 /* Could be non-blocking IO */
626 return SUB_STATE_ERROR;
627 }
628 }
629
630 s->first_packet = 0;
631 if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
632 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,
633 ERR_R_INTERNAL_ERROR);
634 return SUB_STATE_ERROR;
635 }
636 ret = process_message(s, &pkt);
637
638 /* Discard the packet data */
639 s->init_num = 0;
640
641 switch (ret) {
642 case MSG_PROCESS_ERROR:
643 check_fatal(s, SSL_F_READ_STATE_MACHINE);
644 return SUB_STATE_ERROR;
645
646 case MSG_PROCESS_FINISHED_READING:
647 if (SSL_IS_DTLS(s)) {
648 dtls1_stop_timer(s);
649 }
650 return SUB_STATE_FINISHED;
651
652 case MSG_PROCESS_CONTINUE_PROCESSING:
653 st->read_state = READ_STATE_POST_PROCESS;
654 st->read_state_work = WORK_MORE_A;
655 break;
656
657 default:
658 st->read_state = READ_STATE_HEADER;
659 break;
660 }
661 break;
662
663 case READ_STATE_POST_PROCESS:
664 st->read_state_work = post_process_message(s, st->read_state_work);
665 switch (st->read_state_work) {
666 case WORK_ERROR:
667 check_fatal(s, SSL_F_READ_STATE_MACHINE);
668 /* Fall through */
669 case WORK_MORE_A:
670 case WORK_MORE_B:
671 case WORK_MORE_C:
672 return SUB_STATE_ERROR;
673
674 case WORK_FINISHED_CONTINUE:
675 st->read_state = READ_STATE_HEADER;
676 break;
677
678 case WORK_FINISHED_STOP:
679 if (SSL_IS_DTLS(s)) {
680 dtls1_stop_timer(s);
681 }
682 return SUB_STATE_FINISHED;
683 }
684 break;
685
686 default:
687 /* Shouldn't happen */
688 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,
689 ERR_R_INTERNAL_ERROR);
690 return SUB_STATE_ERROR;
691 }
692 }
693 }
694
695 /*
696 * Send a previously constructed message to the peer.
697 */
statem_do_write(SSL * s)698 static int statem_do_write(SSL *s)
699 {
700 OSSL_STATEM *st = &s->statem;
701
702 if (st->hand_state == TLS_ST_CW_CHANGE
703 || st->hand_state == TLS_ST_SW_CHANGE) {
704 if (SSL_IS_DTLS(s))
705 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
706 else
707 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
708 } else {
709 return ssl_do_write(s);
710 }
711 }
712
713 /*
714 * Initialise the MSG_FLOW_WRITING sub-state machine
715 */
init_write_state_machine(SSL * s)716 static void init_write_state_machine(SSL *s)
717 {
718 OSSL_STATEM *st = &s->statem;
719
720 st->write_state = WRITE_STATE_TRANSITION;
721 }
722
723 /*
724 * This function implements the sub-state machine when the message flow is in
725 * MSG_FLOW_WRITING. The valid sub-states and transitions are:
726 *
727 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
728 * | |
729 * | v
730 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
731 * | |
732 * | v
733 * | WRITE_STATE_SEND
734 * | |
735 * | v
736 * | WRITE_STATE_POST_WORK
737 * | |
738 * +-------------+
739 *
740 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
741
742 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
743 * sending of the message. This could result in an NBIO event occurring in
744 * which case control returns to the calling application. When this function
745 * is recalled we will resume in the same state where we left off.
746 *
747 * WRITE_STATE_SEND sends the message and performs any work to be done after
748 * sending.
749 *
750 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
751 * message has been completed. As for WRITE_STATE_PRE_WORK this could also
752 * result in an NBIO event.
753 */
write_state_machine(SSL * s)754 static SUB_STATE_RETURN write_state_machine(SSL *s)
755 {
756 OSSL_STATEM *st = &s->statem;
757 int ret;
758 WRITE_TRAN(*transition) (SSL *s);
759 WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst);
760 WORK_STATE(*post_work) (SSL *s, WORK_STATE wst);
761 int (*get_construct_message_f) (SSL *s, WPACKET *pkt,
762 int (**confunc) (SSL *s, WPACKET *pkt),
763 int *mt);
764 void (*cb) (const SSL *ssl, int type, int val) = NULL;
765 int (*confunc) (SSL *s, WPACKET *pkt);
766 int mt;
767 WPACKET pkt;
768
769 cb = get_callback(s);
770
771 if (s->server) {
772 transition = ossl_statem_server_write_transition;
773 pre_work = ossl_statem_server_pre_work;
774 post_work = ossl_statem_server_post_work;
775 get_construct_message_f = ossl_statem_server_construct_message;
776 } else {
777 transition = ossl_statem_client_write_transition;
778 pre_work = ossl_statem_client_pre_work;
779 post_work = ossl_statem_client_post_work;
780 get_construct_message_f = ossl_statem_client_construct_message;
781 }
782
783 while (1) {
784 switch (st->write_state) {
785 case WRITE_STATE_TRANSITION:
786 if (cb != NULL) {
787 /* Notify callback of an impending state change */
788 if (s->server)
789 cb(s, SSL_CB_ACCEPT_LOOP, 1);
790 else
791 cb(s, SSL_CB_CONNECT_LOOP, 1);
792 }
793 switch (transition(s)) {
794 case WRITE_TRAN_CONTINUE:
795 st->write_state = WRITE_STATE_PRE_WORK;
796 st->write_state_work = WORK_MORE_A;
797 break;
798
799 case WRITE_TRAN_FINISHED:
800 return SUB_STATE_FINISHED;
801 break;
802
803 case WRITE_TRAN_ERROR:
804 check_fatal(s, SSL_F_WRITE_STATE_MACHINE);
805 return SUB_STATE_ERROR;
806 }
807 break;
808
809 case WRITE_STATE_PRE_WORK:
810 switch (st->write_state_work = pre_work(s, st->write_state_work)) {
811 case WORK_ERROR:
812 check_fatal(s, SSL_F_WRITE_STATE_MACHINE);
813 /* Fall through */
814 case WORK_MORE_A:
815 case WORK_MORE_B:
816 case WORK_MORE_C:
817 return SUB_STATE_ERROR;
818
819 case WORK_FINISHED_CONTINUE:
820 st->write_state = WRITE_STATE_SEND;
821 break;
822
823 case WORK_FINISHED_STOP:
824 return SUB_STATE_END_HANDSHAKE;
825 }
826 if (!get_construct_message_f(s, &pkt, &confunc, &mt)) {
827 /* SSLfatal() already called */
828 return SUB_STATE_ERROR;
829 }
830 if (mt == SSL3_MT_DUMMY) {
831 /* Skip construction and sending. This isn't a "real" state */
832 st->write_state = WRITE_STATE_POST_WORK;
833 st->write_state_work = WORK_MORE_A;
834 break;
835 }
836 if (!WPACKET_init(&pkt, s->init_buf)
837 || !ssl_set_handshake_header(s, &pkt, mt)) {
838 WPACKET_cleanup(&pkt);
839 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE,
840 ERR_R_INTERNAL_ERROR);
841 return SUB_STATE_ERROR;
842 }
843 if (confunc != NULL && !confunc(s, &pkt)) {
844 WPACKET_cleanup(&pkt);
845 check_fatal(s, SSL_F_WRITE_STATE_MACHINE);
846 return SUB_STATE_ERROR;
847 }
848 if (!ssl_close_construct_packet(s, &pkt, mt)
849 || !WPACKET_finish(&pkt)) {
850 WPACKET_cleanup(&pkt);
851 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE,
852 ERR_R_INTERNAL_ERROR);
853 return SUB_STATE_ERROR;
854 }
855
856 /* Fall through */
857
858 case WRITE_STATE_SEND:
859 if (SSL_IS_DTLS(s) && st->use_timer) {
860 dtls1_start_timer(s);
861 }
862 ret = statem_do_write(s);
863 if (ret <= 0) {
864 return SUB_STATE_ERROR;
865 }
866 st->write_state = WRITE_STATE_POST_WORK;
867 st->write_state_work = WORK_MORE_A;
868 /* Fall through */
869
870 case WRITE_STATE_POST_WORK:
871 switch (st->write_state_work = post_work(s, st->write_state_work)) {
872 case WORK_ERROR:
873 check_fatal(s, SSL_F_WRITE_STATE_MACHINE);
874 /* Fall through */
875 case WORK_MORE_A:
876 case WORK_MORE_B:
877 case WORK_MORE_C:
878 return SUB_STATE_ERROR;
879
880 case WORK_FINISHED_CONTINUE:
881 st->write_state = WRITE_STATE_TRANSITION;
882 break;
883
884 case WORK_FINISHED_STOP:
885 return SUB_STATE_END_HANDSHAKE;
886 }
887 break;
888
889 default:
890 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE,
891 ERR_R_INTERNAL_ERROR);
892 return SUB_STATE_ERROR;
893 }
894 }
895 }
896
897 /*
898 * Flush the write BIO
899 */
statem_flush(SSL * s)900 int statem_flush(SSL *s)
901 {
902 s->rwstate = SSL_WRITING;
903 if (BIO_flush(s->wbio) <= 0) {
904 return 0;
905 }
906 s->rwstate = SSL_NOTHING;
907
908 return 1;
909 }
910
911 /*
912 * Called by the record layer to determine whether application data is
913 * allowed to be received in the current handshake state or not.
914 *
915 * Return values are:
916 * 1: Yes (application data allowed)
917 * 0: No (application data not allowed)
918 */
ossl_statem_app_data_allowed(SSL * s)919 int ossl_statem_app_data_allowed(SSL *s)
920 {
921 OSSL_STATEM *st = &s->statem;
922
923 if (st->state == MSG_FLOW_UNINITED)
924 return 0;
925
926 if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
927 return 0;
928
929 if (s->server) {
930 /*
931 * If we're a server and we haven't got as far as writing our
932 * ServerHello yet then we allow app data
933 */
934 if (st->hand_state == TLS_ST_BEFORE
935 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
936 return 1;
937 } else {
938 /*
939 * If we're a client and we haven't read the ServerHello yet then we
940 * allow app data
941 */
942 if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
943 return 1;
944 }
945
946 return 0;
947 }
948
949 /*
950 * This function returns 1 if TLS exporter is ready to export keying
951 * material, or 0 if otherwise.
952 */
ossl_statem_export_allowed(SSL * s)953 int ossl_statem_export_allowed(SSL *s)
954 {
955 return s->s3->previous_server_finished_len != 0
956 && s->statem.hand_state != TLS_ST_SW_FINISHED;
957 }
958
959 /*
960 * Return 1 if early TLS exporter is ready to export keying material,
961 * or 0 if otherwise.
962 */
ossl_statem_export_early_allowed(SSL * s)963 int ossl_statem_export_early_allowed(SSL *s)
964 {
965 /*
966 * The early exporter secret is only present on the server if we
967 * have accepted early_data. It is present on the client as long
968 * as we have sent early_data.
969 */
970 return s->ext.early_data == SSL_EARLY_DATA_ACCEPTED
971 || (!s->server && s->ext.early_data != SSL_EARLY_DATA_NOT_SENT);
972 }
973