1 /*
2 * Copyright 2015-2022 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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 #if defined(__TANDEM) && defined(_SPT_MODEL_)
11 # include <spthread.h>
12 # include <spt_extensions.h> /* timeval */
13 #endif
14
15 #include "internal/cryptlib.h"
16 #include <openssl/rand.h>
17 #include "../ssl_local.h"
18 #include "statem_local.h"
19 #include <assert.h>
20
21 /*
22 * This file implements the SSL/TLS/DTLS state machines.
23 *
24 * There are two primary state machines:
25 *
26 * 1) Message flow state machine
27 * 2) Handshake state machine
28 *
29 * The Message flow state machine controls the reading and sending of messages
30 * including handling of non-blocking IO events, flushing of the underlying
31 * write BIO, handling unexpected messages, etc. It is itself broken into two
32 * separate sub-state machines which control reading and writing respectively.
33 *
34 * The Handshake state machine keeps track of the current SSL/TLS handshake
35 * state. Transitions of the handshake state are the result of events that
36 * occur within the Message flow state machine.
37 *
38 * Overall it looks like this:
39 *
40 * --------------------------------------------- -------------------
41 * | | | |
42 * | Message flow state machine | | |
43 * | | | |
44 * | -------------------- -------------------- | Transition | Handshake state |
45 * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event | machine |
46 * | | sub-state | | sub-state | |----------->| |
47 * | | machine for | | machine for | | | |
48 * | | reading messages | | writing messages | | | |
49 * | -------------------- -------------------- | | |
50 * | | | |
51 * --------------------------------------------- -------------------
52 *
53 */
54
55 /* Sub state machine return values */
56 typedef enum {
57 /* Something bad happened or NBIO */
58 SUB_STATE_ERROR,
59 /* Sub state finished go to the next sub state */
60 SUB_STATE_FINISHED,
61 /* Sub state finished and handshake was completed */
62 SUB_STATE_END_HANDSHAKE
63 } SUB_STATE_RETURN;
64
65 static int state_machine(SSL *s, int server);
66 static void init_read_state_machine(SSL *s);
67 static SUB_STATE_RETURN read_state_machine(SSL *s);
68 static void init_write_state_machine(SSL *s);
69 static SUB_STATE_RETURN write_state_machine(SSL *s);
70
SSL_get_state(const SSL * ssl)71 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
72 {
73 return ssl->statem.hand_state;
74 }
75
SSL_in_init(const SSL * s)76 int SSL_in_init(const SSL *s)
77 {
78 return s->statem.in_init;
79 }
80
SSL_is_init_finished(const SSL * s)81 int SSL_is_init_finished(const SSL *s)
82 {
83 return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);
84 }
85
SSL_in_before(const SSL * s)86 int SSL_in_before(const SSL *s)
87 {
88 /*
89 * Historically being "in before" meant before anything had happened. In the
90 * current code though we remain in the "before" state for a while after we
91 * have started the handshake process (e.g. as a server waiting for the
92 * first message to arrive). There "in before" is taken to mean "in before"
93 * and not started any handshake process yet.
94 */
95 return (s->statem.hand_state == TLS_ST_BEFORE)
96 && (s->statem.state == MSG_FLOW_UNINITED);
97 }
98
99 /*
100 * Clear the state machine state and reset back to MSG_FLOW_UNINITED
101 */
ossl_statem_clear(SSL * s)102 void ossl_statem_clear(SSL *s)
103 {
104 s->statem.state = MSG_FLOW_UNINITED;
105 s->statem.hand_state = TLS_ST_BEFORE;
106 s->statem.in_init = 1;
107 s->statem.no_cert_verify = 0;
108 }
109
110 /*
111 * Set the state machine up ready for a renegotiation handshake
112 */
ossl_statem_set_renegotiate(SSL * s)113 void ossl_statem_set_renegotiate(SSL *s)
114 {
115 s->statem.in_init = 1;
116 s->statem.request_state = TLS_ST_SW_HELLO_REQ;
117 }
118
ossl_statem_send_fatal(SSL * s,int al)119 void ossl_statem_send_fatal(SSL *s, int al)
120 {
121 /* We shouldn't call SSLfatal() twice. Once is enough */
122 if (s->statem.in_init && s->statem.state == MSG_FLOW_ERROR)
123 return;
124 s->statem.in_init = 1;
125 s->statem.state = MSG_FLOW_ERROR;
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 * Error reporting building block that's used instead of ERR_set_error().
133 * In addition to what ERR_set_error() does, this puts the state machine
134 * into an error state and sends an alert if appropriate.
135 * This is a permanent error for the current connection.
136 */
ossl_statem_fatal(SSL * s,int al,int reason,const char * fmt,...)137 void ossl_statem_fatal(SSL *s, int al, int reason, const char *fmt, ...)
138 {
139 va_list args;
140
141 va_start(args, fmt);
142 ERR_vset_error(ERR_LIB_SSL, reason, fmt, args);
143 va_end(args);
144
145 ossl_statem_send_fatal(s, al);
146 }
147
148 /*
149 * This macro should only be called if we are already expecting to be in
150 * a fatal error state. We verify that we are, and set it if not (this would
151 * indicate a bug).
152 */
153 #define check_fatal(s) \
154 do { \
155 if (!ossl_assert((s)->statem.in_init \
156 && (s)->statem.state == MSG_FLOW_ERROR)) \
157 SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_R_MISSING_FATAL); \
158 } while (0)
159
160 /*
161 * Discover whether the current connection is in the error state.
162 *
163 * Valid return values are:
164 * 1: Yes
165 * 0: No
166 */
ossl_statem_in_error(const SSL * s)167 int ossl_statem_in_error(const SSL *s)
168 {
169 if (s->statem.state == MSG_FLOW_ERROR)
170 return 1;
171
172 return 0;
173 }
174
ossl_statem_set_in_init(SSL * s,int init)175 void ossl_statem_set_in_init(SSL *s, int init)
176 {
177 s->statem.in_init = init;
178 }
179
ossl_statem_get_in_handshake(SSL * s)180 int ossl_statem_get_in_handshake(SSL *s)
181 {
182 return s->statem.in_handshake;
183 }
184
ossl_statem_set_in_handshake(SSL * s,int inhand)185 void ossl_statem_set_in_handshake(SSL *s, int inhand)
186 {
187 if (inhand)
188 s->statem.in_handshake++;
189 else
190 s->statem.in_handshake--;
191 }
192
193 /* Are we in a sensible state to skip over unreadable early data? */
ossl_statem_skip_early_data(SSL * s)194 int ossl_statem_skip_early_data(SSL *s)
195 {
196 if (s->ext.early_data != SSL_EARLY_DATA_REJECTED)
197 return 0;
198
199 if (!s->server
200 || s->statem.hand_state != TLS_ST_EARLY_DATA
201 || s->hello_retry_request == SSL_HRR_COMPLETE)
202 return 0;
203
204 return 1;
205 }
206
207 /*
208 * Called when we are in SSL_read*(), SSL_write*(), or SSL_accept()
209 * /SSL_connect()/SSL_do_handshake(). Used to test whether we are in an early
210 * data state and whether we should attempt to move the handshake on if so.
211 * |sending| is 1 if we are attempting to send data (SSL_write*()), 0 if we are
212 * attempting to read data (SSL_read*()), or -1 if we are in SSL_do_handshake()
213 * or similar.
214 */
ossl_statem_check_finish_init(SSL * s,int sending)215 void ossl_statem_check_finish_init(SSL *s, int sending)
216 {
217 if (sending == -1) {
218 if (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END
219 || s->statem.hand_state == TLS_ST_EARLY_DATA) {
220 ossl_statem_set_in_init(s, 1);
221 if (s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {
222 /*
223 * SSL_connect() or SSL_do_handshake() has been called directly.
224 * We don't allow any more writing of early data.
225 */
226 s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;
227 }
228 }
229 } else if (!s->server) {
230 if ((sending && (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END
231 || s->statem.hand_state == TLS_ST_EARLY_DATA)
232 && s->early_data_state != SSL_EARLY_DATA_WRITING)
233 || (!sending && s->statem.hand_state == TLS_ST_EARLY_DATA)) {
234 ossl_statem_set_in_init(s, 1);
235 /*
236 * SSL_write() has been called directly. We don't allow any more
237 * writing of early data.
238 */
239 if (sending && s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY)
240 s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;
241 }
242 } else {
243 if (s->early_data_state == SSL_EARLY_DATA_FINISHED_READING
244 && s->statem.hand_state == TLS_ST_EARLY_DATA)
245 ossl_statem_set_in_init(s, 1);
246 }
247 }
248
ossl_statem_set_hello_verify_done(SSL * s)249 void ossl_statem_set_hello_verify_done(SSL *s)
250 {
251 s->statem.state = MSG_FLOW_UNINITED;
252 s->statem.in_init = 1;
253 /*
254 * This will get reset (briefly) back to TLS_ST_BEFORE when we enter
255 * state_machine() because |state| is MSG_FLOW_UNINITED, but until then any
256 * calls to SSL_in_before() will return false. Also calls to
257 * SSL_state_string() and SSL_state_string_long() will return something
258 * sensible.
259 */
260 s->statem.hand_state = TLS_ST_SR_CLNT_HELLO;
261 }
262
ossl_statem_connect(SSL * s)263 int ossl_statem_connect(SSL *s)
264 {
265 return state_machine(s, 0);
266 }
267
ossl_statem_accept(SSL * s)268 int ossl_statem_accept(SSL *s)
269 {
270 return state_machine(s, 1);
271 }
272
273 typedef void (*info_cb) (const SSL *, int, int);
274
get_callback(SSL * s)275 static info_cb get_callback(SSL *s)
276 {
277 if (s->info_callback != NULL)
278 return s->info_callback;
279 else if (s->ctx->info_callback != NULL)
280 return s->ctx->info_callback;
281
282 return NULL;
283 }
284
285 /*
286 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
287 * MSG_FLOW_FINISHED state and finish in MSG_FLOW_FINISHED. Valid states and
288 * transitions are as follows:
289 *
290 * MSG_FLOW_UNINITED MSG_FLOW_FINISHED
291 * | |
292 * +-----------------------+
293 * v
294 * MSG_FLOW_WRITING <---> MSG_FLOW_READING
295 * |
296 * V
297 * MSG_FLOW_FINISHED
298 * |
299 * V
300 * [SUCCESS]
301 *
302 * We may exit at any point due to an error or NBIO event. If an NBIO event
303 * occurs then we restart at the point we left off when we are recalled.
304 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
305 *
306 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
307 * into that state at any point in the event that an irrecoverable error occurs.
308 *
309 * Valid return values are:
310 * 1: Success
311 * <=0: NBIO or error
312 */
state_machine(SSL * s,int server)313 static int state_machine(SSL *s, int server)
314 {
315 BUF_MEM *buf = NULL;
316 void (*cb) (const SSL *ssl, int type, int val) = NULL;
317 OSSL_STATEM *st = &s->statem;
318 int ret = -1;
319 int ssret;
320
321 if (st->state == MSG_FLOW_ERROR) {
322 /* Shouldn't have been called if we're already in the error state */
323 return -1;
324 }
325
326 ERR_clear_error();
327 clear_sys_error();
328
329 cb = get_callback(s);
330
331 st->in_handshake++;
332 if (!SSL_in_init(s) || SSL_in_before(s)) {
333 /*
334 * If we are stateless then we already called SSL_clear() - don't do
335 * it again and clear the STATELESS flag itself.
336 */
337 if ((s->s3.flags & TLS1_FLAGS_STATELESS) == 0 && !SSL_clear(s))
338 return -1;
339 }
340 #ifndef OPENSSL_NO_SCTP
341 if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) {
342 /*
343 * Notify SCTP BIO socket to enter handshake mode and prevent stream
344 * identifier other than 0.
345 */
346 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
347 st->in_handshake, NULL);
348 }
349 #endif
350
351 /* Initialise state machine */
352 if (st->state == MSG_FLOW_UNINITED
353 || st->state == MSG_FLOW_FINISHED) {
354 if (st->state == MSG_FLOW_UNINITED) {
355 st->hand_state = TLS_ST_BEFORE;
356 st->request_state = TLS_ST_BEFORE;
357 }
358
359 s->server = server;
360 if (cb != NULL) {
361 if (SSL_IS_FIRST_HANDSHAKE(s) || !SSL_IS_TLS13(s))
362 cb(s, SSL_CB_HANDSHAKE_START, 1);
363 }
364
365 /*
366 * Fatal errors in this block don't send an alert because we have
367 * failed to even initialise properly. Sending an alert is probably
368 * doomed to failure.
369 */
370
371 if (SSL_IS_DTLS(s)) {
372 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
373 (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
374 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
375 goto end;
376 }
377 } else {
378 if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
379 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
380 goto end;
381 }
382 }
383
384 if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
385 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
386 goto end;
387 }
388
389 if (s->init_buf == NULL) {
390 if ((buf = BUF_MEM_new()) == NULL) {
391 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
392 goto end;
393 }
394 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
395 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
396 goto end;
397 }
398 s->init_buf = buf;
399 buf = NULL;
400 }
401
402 if (!ssl3_setup_buffers(s)) {
403 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
404 goto end;
405 }
406 s->init_num = 0;
407
408 /*
409 * Should have been reset by tls_process_finished, too.
410 */
411 s->s3.change_cipher_spec = 0;
412
413 /*
414 * Ok, we now need to push on a buffering BIO ...but not with
415 * SCTP
416 */
417 #ifndef OPENSSL_NO_SCTP
418 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
419 #endif
420 if (!ssl_init_wbio_buffer(s)) {
421 SSLfatal(s, SSL_AD_NO_ALERT, ERR_R_INTERNAL_ERROR);
422 goto end;
423 }
424
425 if ((SSL_in_before(s))
426 || s->renegotiate) {
427 if (!tls_setup_handshake(s)) {
428 /* SSLfatal() already called */
429 goto end;
430 }
431
432 if (SSL_IS_FIRST_HANDSHAKE(s))
433 st->read_state_first_init = 1;
434 }
435
436 st->state = MSG_FLOW_WRITING;
437 init_write_state_machine(s);
438 }
439
440 while (st->state != MSG_FLOW_FINISHED) {
441 if (st->state == MSG_FLOW_READING) {
442 ssret = read_state_machine(s);
443 if (ssret == SUB_STATE_FINISHED) {
444 st->state = MSG_FLOW_WRITING;
445 init_write_state_machine(s);
446 } else {
447 /* NBIO or error */
448 goto end;
449 }
450 } else if (st->state == MSG_FLOW_WRITING) {
451 ssret = write_state_machine(s);
452 if (ssret == SUB_STATE_FINISHED) {
453 st->state = MSG_FLOW_READING;
454 init_read_state_machine(s);
455 } else if (ssret == SUB_STATE_END_HANDSHAKE) {
456 st->state = MSG_FLOW_FINISHED;
457 } else {
458 /* NBIO or error */
459 goto end;
460 }
461 } else {
462 /* Error */
463 check_fatal(s);
464 ERR_raise(ERR_LIB_SSL, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
465 goto end;
466 }
467 }
468
469 ret = 1;
470
471 end:
472 st->in_handshake--;
473
474 #ifndef OPENSSL_NO_SCTP
475 if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) {
476 /*
477 * Notify SCTP BIO socket to leave handshake mode and allow stream
478 * identifier other than 0.
479 */
480 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
481 st->in_handshake, NULL);
482 }
483 #endif
484
485 BUF_MEM_free(buf);
486 if (cb != NULL) {
487 if (server)
488 cb(s, SSL_CB_ACCEPT_EXIT, ret);
489 else
490 cb(s, SSL_CB_CONNECT_EXIT, ret);
491 }
492 return ret;
493 }
494
495 /*
496 * Initialise the MSG_FLOW_READING sub-state machine
497 */
init_read_state_machine(SSL * s)498 static void init_read_state_machine(SSL *s)
499 {
500 OSSL_STATEM *st = &s->statem;
501
502 st->read_state = READ_STATE_HEADER;
503 }
504
grow_init_buf(SSL * s,size_t size)505 static int grow_init_buf(SSL *s, size_t size) {
506
507 size_t msg_offset = (char *)s->init_msg - s->init_buf->data;
508
509 if (!BUF_MEM_grow_clean(s->init_buf, (int)size))
510 return 0;
511
512 if (size < msg_offset)
513 return 0;
514
515 s->init_msg = s->init_buf->data + msg_offset;
516
517 return 1;
518 }
519
520 /*
521 * This function implements the sub-state machine when the message flow is in
522 * MSG_FLOW_READING. The valid sub-states and transitions are:
523 *
524 * READ_STATE_HEADER <--+<-------------+
525 * | | |
526 * v | |
527 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
528 * | |
529 * +----------------------------+
530 * v
531 * [SUB_STATE_FINISHED]
532 *
533 * READ_STATE_HEADER has the responsibility for reading in the message header
534 * and transitioning the state of the handshake state machine.
535 *
536 * READ_STATE_BODY reads in the rest of the message and then subsequently
537 * processes it.
538 *
539 * READ_STATE_POST_PROCESS is an optional step that may occur if some post
540 * processing activity performed on the message may block.
541 *
542 * Any of the above states could result in an NBIO event occurring in which case
543 * control returns to the calling application. When this function is recalled we
544 * will resume in the same state where we left off.
545 */
read_state_machine(SSL * s)546 static SUB_STATE_RETURN read_state_machine(SSL *s)
547 {
548 OSSL_STATEM *st = &s->statem;
549 int ret, mt;
550 size_t len = 0;
551 int (*transition) (SSL *s, int mt);
552 PACKET pkt;
553 MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt);
554 WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst);
555 size_t (*max_message_size) (SSL *s);
556 void (*cb) (const SSL *ssl, int type, int val) = NULL;
557
558 cb = get_callback(s);
559
560 if (s->server) {
561 transition = ossl_statem_server_read_transition;
562 process_message = ossl_statem_server_process_message;
563 max_message_size = ossl_statem_server_max_message_size;
564 post_process_message = ossl_statem_server_post_process_message;
565 } else {
566 transition = ossl_statem_client_read_transition;
567 process_message = ossl_statem_client_process_message;
568 max_message_size = ossl_statem_client_max_message_size;
569 post_process_message = ossl_statem_client_post_process_message;
570 }
571
572 if (st->read_state_first_init) {
573 s->first_packet = 1;
574 st->read_state_first_init = 0;
575 }
576
577 while (1) {
578 switch (st->read_state) {
579 case READ_STATE_HEADER:
580 /* Get the state the peer wants to move to */
581 if (SSL_IS_DTLS(s)) {
582 /*
583 * In DTLS we get the whole message in one go - header and body
584 */
585 ret = dtls_get_message(s, &mt);
586 } else {
587 ret = tls_get_message_header(s, &mt);
588 }
589
590 if (ret == 0) {
591 /* Could be non-blocking IO */
592 return SUB_STATE_ERROR;
593 }
594
595 if (cb != NULL) {
596 /* Notify callback of an impending state change */
597 if (s->server)
598 cb(s, SSL_CB_ACCEPT_LOOP, 1);
599 else
600 cb(s, SSL_CB_CONNECT_LOOP, 1);
601 }
602 /*
603 * Validate that we are allowed to move to the new state and move
604 * to that state if so
605 */
606 if (!transition(s, mt))
607 return SUB_STATE_ERROR;
608
609 if (s->s3.tmp.message_size > max_message_size(s)) {
610 SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
611 SSL_R_EXCESSIVE_MESSAGE_SIZE);
612 return SUB_STATE_ERROR;
613 }
614
615 /* dtls_get_message already did this */
616 if (!SSL_IS_DTLS(s)
617 && s->s3.tmp.message_size > 0
618 && !grow_init_buf(s, s->s3.tmp.message_size
619 + SSL3_HM_HEADER_LENGTH)) {
620 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_BUF_LIB);
621 return SUB_STATE_ERROR;
622 }
623
624 st->read_state = READ_STATE_BODY;
625 /* Fall through */
626
627 case READ_STATE_BODY:
628 if (SSL_IS_DTLS(s)) {
629 /*
630 * Actually we already have the body, but we give DTLS the
631 * opportunity to do any further processing.
632 */
633 ret = dtls_get_message_body(s, &len);
634 } else {
635 ret = tls_get_message_body(s, &len);
636 }
637 if (ret == 0) {
638 /* Could be non-blocking IO */
639 return SUB_STATE_ERROR;
640 }
641
642 s->first_packet = 0;
643 if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
644 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
645 return SUB_STATE_ERROR;
646 }
647 ret = process_message(s, &pkt);
648
649 /* Discard the packet data */
650 s->init_num = 0;
651
652 switch (ret) {
653 case MSG_PROCESS_ERROR:
654 check_fatal(s);
655 return SUB_STATE_ERROR;
656
657 case MSG_PROCESS_FINISHED_READING:
658 if (SSL_IS_DTLS(s)) {
659 dtls1_stop_timer(s);
660 }
661 return SUB_STATE_FINISHED;
662
663 case MSG_PROCESS_CONTINUE_PROCESSING:
664 st->read_state = READ_STATE_POST_PROCESS;
665 st->read_state_work = WORK_MORE_A;
666 break;
667
668 default:
669 st->read_state = READ_STATE_HEADER;
670 break;
671 }
672 break;
673
674 case READ_STATE_POST_PROCESS:
675 st->read_state_work = post_process_message(s, st->read_state_work);
676 switch (st->read_state_work) {
677 case WORK_ERROR:
678 check_fatal(s);
679 /* Fall through */
680 case WORK_MORE_A:
681 case WORK_MORE_B:
682 case WORK_MORE_C:
683 return SUB_STATE_ERROR;
684
685 case WORK_FINISHED_CONTINUE:
686 st->read_state = READ_STATE_HEADER;
687 break;
688
689 case WORK_FINISHED_STOP:
690 if (SSL_IS_DTLS(s)) {
691 dtls1_stop_timer(s);
692 }
693 return SUB_STATE_FINISHED;
694 }
695 break;
696
697 default:
698 /* Shouldn't happen */
699 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
700 return SUB_STATE_ERROR;
701 }
702 }
703 }
704
705 /*
706 * Send a previously constructed message to the peer.
707 */
statem_do_write(SSL * s)708 static int statem_do_write(SSL *s)
709 {
710 OSSL_STATEM *st = &s->statem;
711
712 if (st->hand_state == TLS_ST_CW_CHANGE
713 || st->hand_state == TLS_ST_SW_CHANGE) {
714 if (SSL_IS_DTLS(s))
715 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
716 else
717 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
718 } else {
719 return ssl_do_write(s);
720 }
721 }
722
723 /*
724 * Initialise the MSG_FLOW_WRITING sub-state machine
725 */
init_write_state_machine(SSL * s)726 static void init_write_state_machine(SSL *s)
727 {
728 OSSL_STATEM *st = &s->statem;
729
730 st->write_state = WRITE_STATE_TRANSITION;
731 }
732
733 /*
734 * This function implements the sub-state machine when the message flow is in
735 * MSG_FLOW_WRITING. The valid sub-states and transitions are:
736 *
737 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
738 * | |
739 * | v
740 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
741 * | |
742 * | v
743 * | WRITE_STATE_SEND
744 * | |
745 * | v
746 * | WRITE_STATE_POST_WORK
747 * | |
748 * +-------------+
749 *
750 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
751
752 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
753 * sending of the message. This could result in an NBIO event occurring in
754 * which case control returns to the calling application. When this function
755 * is recalled we will resume in the same state where we left off.
756 *
757 * WRITE_STATE_SEND sends the message and performs any work to be done after
758 * sending.
759 *
760 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
761 * message has been completed. As for WRITE_STATE_PRE_WORK this could also
762 * result in an NBIO event.
763 */
write_state_machine(SSL * s)764 static SUB_STATE_RETURN write_state_machine(SSL *s)
765 {
766 OSSL_STATEM *st = &s->statem;
767 int ret;
768 WRITE_TRAN(*transition) (SSL *s);
769 WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst);
770 WORK_STATE(*post_work) (SSL *s, WORK_STATE wst);
771 int (*get_construct_message_f) (SSL *s, WPACKET *pkt,
772 int (**confunc) (SSL *s, WPACKET *pkt),
773 int *mt);
774 void (*cb) (const SSL *ssl, int type, int val) = NULL;
775 int (*confunc) (SSL *s, WPACKET *pkt);
776 int mt;
777 WPACKET pkt;
778
779 cb = get_callback(s);
780
781 if (s->server) {
782 transition = ossl_statem_server_write_transition;
783 pre_work = ossl_statem_server_pre_work;
784 post_work = ossl_statem_server_post_work;
785 get_construct_message_f = ossl_statem_server_construct_message;
786 } else {
787 transition = ossl_statem_client_write_transition;
788 pre_work = ossl_statem_client_pre_work;
789 post_work = ossl_statem_client_post_work;
790 get_construct_message_f = ossl_statem_client_construct_message;
791 }
792
793 while (1) {
794 switch (st->write_state) {
795 case WRITE_STATE_TRANSITION:
796 if (cb != NULL) {
797 /* Notify callback of an impending state change */
798 if (s->server)
799 cb(s, SSL_CB_ACCEPT_LOOP, 1);
800 else
801 cb(s, SSL_CB_CONNECT_LOOP, 1);
802 }
803 switch (transition(s)) {
804 case WRITE_TRAN_CONTINUE:
805 st->write_state = WRITE_STATE_PRE_WORK;
806 st->write_state_work = WORK_MORE_A;
807 break;
808
809 case WRITE_TRAN_FINISHED:
810 return SUB_STATE_FINISHED;
811 break;
812
813 case WRITE_TRAN_ERROR:
814 check_fatal(s);
815 return SUB_STATE_ERROR;
816 }
817 break;
818
819 case WRITE_STATE_PRE_WORK:
820 switch (st->write_state_work = pre_work(s, st->write_state_work)) {
821 case WORK_ERROR:
822 check_fatal(s);
823 /* Fall through */
824 case WORK_MORE_A:
825 case WORK_MORE_B:
826 case WORK_MORE_C:
827 return SUB_STATE_ERROR;
828
829 case WORK_FINISHED_CONTINUE:
830 st->write_state = WRITE_STATE_SEND;
831 break;
832
833 case WORK_FINISHED_STOP:
834 return SUB_STATE_END_HANDSHAKE;
835 }
836 if (!get_construct_message_f(s, &pkt, &confunc, &mt)) {
837 /* SSLfatal() already called */
838 return SUB_STATE_ERROR;
839 }
840 if (mt == SSL3_MT_DUMMY) {
841 /* Skip construction and sending. This isn't a "real" state */
842 st->write_state = WRITE_STATE_POST_WORK;
843 st->write_state_work = WORK_MORE_A;
844 break;
845 }
846 if (!WPACKET_init(&pkt, s->init_buf)
847 || !ssl_set_handshake_header(s, &pkt, mt)) {
848 WPACKET_cleanup(&pkt);
849 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
850 return SUB_STATE_ERROR;
851 }
852 if (confunc != NULL) {
853 int tmpret;
854
855 tmpret = confunc(s, &pkt);
856 if (tmpret <= 0) {
857 WPACKET_cleanup(&pkt);
858 check_fatal(s);
859 return SUB_STATE_ERROR;
860 } else if (tmpret == 2) {
861 /*
862 * The construction function decided not to construct the
863 * message after all and continue. Skip sending.
864 */
865 WPACKET_cleanup(&pkt);
866 st->write_state = WRITE_STATE_POST_WORK;
867 st->write_state_work = WORK_MORE_A;
868 break;
869 } /* else success */
870 }
871 if (!ssl_close_construct_packet(s, &pkt, mt)
872 || !WPACKET_finish(&pkt)) {
873 WPACKET_cleanup(&pkt);
874 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
875 return SUB_STATE_ERROR;
876 }
877
878 /* Fall through */
879
880 case WRITE_STATE_SEND:
881 if (SSL_IS_DTLS(s) && st->use_timer) {
882 dtls1_start_timer(s);
883 }
884 ret = statem_do_write(s);
885 if (ret <= 0) {
886 return SUB_STATE_ERROR;
887 }
888 st->write_state = WRITE_STATE_POST_WORK;
889 st->write_state_work = WORK_MORE_A;
890 /* Fall through */
891
892 case WRITE_STATE_POST_WORK:
893 switch (st->write_state_work = post_work(s, st->write_state_work)) {
894 case WORK_ERROR:
895 check_fatal(s);
896 /* Fall through */
897 case WORK_MORE_A:
898 case WORK_MORE_B:
899 case WORK_MORE_C:
900 return SUB_STATE_ERROR;
901
902 case WORK_FINISHED_CONTINUE:
903 st->write_state = WRITE_STATE_TRANSITION;
904 break;
905
906 case WORK_FINISHED_STOP:
907 return SUB_STATE_END_HANDSHAKE;
908 }
909 break;
910
911 default:
912 SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
913 return SUB_STATE_ERROR;
914 }
915 }
916 }
917
918 /*
919 * Flush the write BIO
920 */
statem_flush(SSL * s)921 int statem_flush(SSL *s)
922 {
923 s->rwstate = SSL_WRITING;
924 if (BIO_flush(s->wbio) <= 0) {
925 return 0;
926 }
927 s->rwstate = SSL_NOTHING;
928
929 return 1;
930 }
931
932 /*
933 * Called by the record layer to determine whether application data is
934 * allowed to be received in the current handshake state or not.
935 *
936 * Return values are:
937 * 1: Yes (application data allowed)
938 * 0: No (application data not allowed)
939 */
ossl_statem_app_data_allowed(SSL * s)940 int ossl_statem_app_data_allowed(SSL *s)
941 {
942 OSSL_STATEM *st = &s->statem;
943
944 if (st->state == MSG_FLOW_UNINITED)
945 return 0;
946
947 if (!s->s3.in_read_app_data || (s->s3.total_renegotiations == 0))
948 return 0;
949
950 if (s->server) {
951 /*
952 * If we're a server and we haven't got as far as writing our
953 * ServerHello yet then we allow app data
954 */
955 if (st->hand_state == TLS_ST_BEFORE
956 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
957 return 1;
958 } else {
959 /*
960 * If we're a client and we haven't read the ServerHello yet then we
961 * allow app data
962 */
963 if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
964 return 1;
965 }
966
967 return 0;
968 }
969
970 /*
971 * This function returns 1 if TLS exporter is ready to export keying
972 * material, or 0 if otherwise.
973 */
ossl_statem_export_allowed(SSL * s)974 int ossl_statem_export_allowed(SSL *s)
975 {
976 return s->s3.previous_server_finished_len != 0
977 && s->statem.hand_state != TLS_ST_SW_FINISHED;
978 }
979
980 /*
981 * Return 1 if early TLS exporter is ready to export keying material,
982 * or 0 if otherwise.
983 */
ossl_statem_export_early_allowed(SSL * s)984 int ossl_statem_export_early_allowed(SSL *s)
985 {
986 /*
987 * The early exporter secret is only present on the server if we
988 * have accepted early_data. It is present on the client as long
989 * as we have sent early_data.
990 */
991 return s->ext.early_data == SSL_EARLY_DATA_ACCEPTED
992 || (!s->server && s->ext.early_data != SSL_EARLY_DATA_NOT_SENT);
993 }
994