1 /* ssl/statem/statem.c */
3 * Written by Matt Caswell for the OpenSSL project.
5 /* ====================================================================
6 * Copyright (c) 1998-2015 The OpenSSL Project. All rights reserved.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@openssl.org.
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
34 * 6. Redistributions of any form whatsoever must retain the following
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
59 #include <openssl/rand.h>
60 #include "../ssl_locl.h"
61 #include "statem_locl.h"
64 * This file implements the SSL/TLS/DTLS state machines.
66 * There are two primary state machines:
68 * 1) Message flow state machine
69 * 2) Handshake state machine
71 * The Message flow state machine controls the reading and sending of messages
72 * including handling of non-blocking IO events, flushing of the underlying
73 * write BIO, handling unexpected messages, etc. It is itself broken into two
74 * separate sub-state machines which control reading and writing respectively.
76 * The Handshake state machine keeps track of the current SSL/TLS handshake
77 * state. Transitions of the handshake state are the result of events that
78 * occur within the Message flow state machine.
80 * Overall it looks like this:
82 * --------------------------------------------- -------------------
84 * | Message flow state machine | | |
86 * | -------------------- -------------------- | Transition | Handshake state |
87 * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event | machine |
88 * | | sub-state | | sub-state | |----------->| |
89 * | | machine for | | machine for | | | |
90 * | | reading messages | | writing messages | | | |
91 * | -------------------- -------------------- | | |
93 * --------------------------------------------- -------------------
97 /* Sub state machine return values */
99 /* Something bad happened or NBIO */
101 /* Sub state finished go to the next sub state */
103 /* Sub state finished and handshake was completed */
104 SUB_STATE_END_HANDSHAKE
107 static int state_machine(SSL *s, int server);
108 static void init_read_state_machine(SSL *s);
109 static SUB_STATE_RETURN read_state_machine(SSL *s);
110 static void init_write_state_machine(SSL *s);
111 static SUB_STATE_RETURN write_state_machine(SSL *s);
113 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
115 return ssl->statem.hand_state;
118 int SSL_in_init(SSL *s)
120 return s->statem.in_init;
123 int SSL_is_init_finished(SSL *s)
125 return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);
128 int SSL_in_before(SSL *s)
131 * Historically being "in before" meant before anything had happened. In the
132 * current code though we remain in the "before" state for a while after we
133 * have started the handshake process (e.g. as a server waiting for the
134 * first message to arrive). There "in before" is taken to mean "in before"
135 * and not started any handshake process yet.
137 return (s->statem.hand_state == TLS_ST_BEFORE)
138 && (s->statem.state == MSG_FLOW_UNINITED);
142 * Clear the state machine state and reset back to MSG_FLOW_UNINITED
144 void ossl_statem_clear(SSL *s)
146 s->statem.state = MSG_FLOW_UNINITED;
147 s->statem.hand_state = TLS_ST_BEFORE;
148 s->statem.in_init = 1;
149 s->statem.no_cert_verify = 0;
153 * Set the state machine up ready for a renegotiation handshake
155 void ossl_statem_set_renegotiate(SSL *s)
157 s->statem.state = MSG_FLOW_RENEGOTIATE;
158 s->statem.in_init = 1;
162 * Put the state machine into an error state. This is a permanent error for
163 * the current connection.
165 void ossl_statem_set_error(SSL *s)
167 s->statem.state = MSG_FLOW_ERROR;
171 * Discover whether the current connection is in the error state.
173 * Valid return values are:
177 int ossl_statem_in_error(const SSL *s)
179 if (s->statem.state == MSG_FLOW_ERROR)
185 void ossl_statem_set_in_init(SSL *s, int init)
187 s->statem.in_init = init;
190 int ossl_statem_connect(SSL *s) {
191 return state_machine(s, 0);
194 int ossl_statem_accept(SSL *s)
196 return state_machine(s, 1);
199 static void (*get_callback(SSL *s))(const SSL *, int, int)
201 if (s->info_callback != NULL)
202 return s->info_callback;
203 else if (s->ctx->info_callback != NULL)
204 return s->ctx->info_callback;
210 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
211 * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
212 * transitions are as follows:
214 * MSG_FLOW_UNINITED MSG_FLOW_RENEGOTIATE
216 * +-----------------------+
218 * MSG_FLOW_WRITING <---> MSG_FLOW_READING
226 * We may exit at any point due to an error or NBIO event. If an NBIO event
227 * occurs then we restart at the point we left off when we are recalled.
228 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
230 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
231 * into that state at any point in the event that an irrecoverable error occurs.
233 * Valid return values are:
237 static int state_machine(SSL *s, int server) {
239 unsigned long Time = (unsigned long)time(NULL);
240 void (*cb) (const SSL *ssl, int type, int val) = NULL;
241 OSSL_STATEM *st = &s->statem;
245 if (st->state == MSG_FLOW_ERROR) {
246 /* Shouldn't have been called if we're already in the error state */
250 RAND_add(&Time, sizeof(Time), 0);
254 cb = get_callback(s);
257 if (!SSL_in_init(s) || SSL_in_before(s)) {
262 #ifndef OPENSSL_NO_SCTP
263 if (SSL_IS_DTLS(s)) {
265 * Notify SCTP BIO socket to enter handshake mode and prevent stream
266 * identifier other than 0. Will be ignored if no SCTP is used.
268 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
269 s->in_handshake, NULL);
273 #ifndef OPENSSL_NO_HEARTBEATS
275 * If we're awaiting a HeartbeatResponse, pretend we already got and
276 * don't await it anymore, because Heartbeats don't make sense during
279 if (s->tlsext_hb_pending) {
282 s->tlsext_hb_pending = 0;
287 /* Initialise state machine */
289 if (st->state == MSG_FLOW_RENEGOTIATE) {
292 s->ctx->stats.sess_connect_renegotiate++;
295 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
296 if (st->state == MSG_FLOW_UNINITED) {
297 st->hand_state = TLS_ST_BEFORE;
302 cb(s, SSL_CB_HANDSHAKE_START, 1);
304 if (SSL_IS_DTLS(s)) {
305 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
307 || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
308 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
312 if ((s->version >> 8) != SSL3_VERSION_MAJOR
313 && s->version != TLS_ANY_VERSION) {
314 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
319 if (!SSL_IS_DTLS(s)) {
320 if (s->version != TLS_ANY_VERSION &&
321 !ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
322 SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
327 if (s->init_buf == NULL) {
328 if ((buf = BUF_MEM_new()) == NULL) {
331 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
338 if (!ssl3_setup_buffers(s)) {
344 * Should have been reset by tls_process_finished, too.
346 s->s3->change_cipher_spec = 0;
348 if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
350 * Ok, we now need to push on a buffering BIO ...but not with
353 #ifndef OPENSSL_NO_SCTP
354 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
356 if (!ssl_init_wbio_buffer(s, server ? 1 : 0)) {
360 ssl3_init_finished_mac(s);
364 if (st->state != MSG_FLOW_RENEGOTIATE) {
365 s->ctx->stats.sess_accept++;
366 } else if (!s->s3->send_connection_binding &&
368 SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
370 * Server attempting to renegotiate with client that doesn't
371 * support secure renegotiation.
373 SSLerr(SSL_F_STATE_MACHINE,
374 SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
375 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
376 ossl_statem_set_error(s);
380 * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
383 s->ctx->stats.sess_accept_renegotiate++;
386 s->ctx->stats.sess_connect++;
388 /* mark client_random uninitialized */
389 memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
392 s->s3->tmp.cert_request = 0;
394 if (SSL_IS_DTLS(s)) {
399 st->state = MSG_FLOW_WRITING;
400 init_write_state_machine(s);
401 st->read_state_first_init = 1;
404 while(st->state != MSG_FLOW_FINISHED) {
405 if(st->state == MSG_FLOW_READING) {
406 ssret = read_state_machine(s);
407 if (ssret == SUB_STATE_FINISHED) {
408 st->state = MSG_FLOW_WRITING;
409 init_write_state_machine(s);
414 } else if (st->state == MSG_FLOW_WRITING) {
415 ssret = write_state_machine(s);
416 if (ssret == SUB_STATE_FINISHED) {
417 st->state = MSG_FLOW_READING;
418 init_read_state_machine(s);
419 } else if (ssret == SUB_STATE_END_HANDSHAKE) {
420 st->state = MSG_FLOW_FINISHED;
427 ossl_statem_set_error(s);
432 st->state = MSG_FLOW_UNINITED;
438 #ifndef OPENSSL_NO_SCTP
439 if (SSL_IS_DTLS(s)) {
441 * Notify SCTP BIO socket to leave handshake mode and allow stream
442 * identifier other than 0. Will be ignored if no SCTP is used.
444 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
445 s->in_handshake, NULL);
452 cb(s, SSL_CB_ACCEPT_EXIT, ret);
454 cb(s, SSL_CB_CONNECT_EXIT, ret);
460 * Initialise the MSG_FLOW_READING sub-state machine
462 static void init_read_state_machine(SSL *s)
464 OSSL_STATEM *st = &s->statem;
466 st->read_state = READ_STATE_HEADER;
470 * This function implements the sub-state machine when the message flow is in
471 * MSG_FLOW_READING. The valid sub-states and transitions are:
473 * READ_STATE_HEADER <--+<-------------+
476 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
478 * +----------------------------+
480 * [SUB_STATE_FINISHED]
482 * READ_STATE_HEADER has the responsibility for reading in the message header
483 * and transitioning the state of the handshake state machine.
485 * READ_STATE_BODY reads in the rest of the message and then subsequently
488 * READ_STATE_POST_PROCESS is an optional step that may occur if some post
489 * processing activity performed on the message may block.
491 * Any of the above states could result in an NBIO event occuring in which case
492 * control returns to the calling application. When this function is recalled we
493 * will resume in the same state where we left off.
495 static SUB_STATE_RETURN read_state_machine(SSL *s) {
496 OSSL_STATEM *st = &s->statem;
499 int (*transition)(SSL *s, int mt);
501 enum MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
502 enum WORK_STATE (*post_process_message)(SSL *s, enum WORK_STATE wst);
503 unsigned long (*max_message_size)(SSL *s);
504 void (*cb) (const SSL *ssl, int type, int val) = NULL;
506 cb = get_callback(s);
509 transition = server_read_transition;
510 process_message = server_process_message;
511 max_message_size = server_max_message_size;
512 post_process_message = server_post_process_message;
514 transition = client_read_transition;
515 process_message = client_process_message;
516 max_message_size = client_max_message_size;
517 post_process_message = client_post_process_message;
520 if (st->read_state_first_init) {
522 st->read_state_first_init = 0;
526 switch(st->read_state) {
527 case READ_STATE_HEADER:
529 /* Get the state the peer wants to move to */
530 if (SSL_IS_DTLS(s)) {
532 * In DTLS we get the whole message in one go - header and body
534 ret = dtls_get_message(s, &mt, &len);
536 ret = tls_get_message_header(s, &mt);
540 /* Could be non-blocking IO */
541 return SUB_STATE_ERROR;
545 /* Notify callback of an impending state change */
547 cb(s, SSL_CB_ACCEPT_LOOP, 1);
549 cb(s, SSL_CB_CONNECT_LOOP, 1);
552 * Validate that we are allowed to move to the new state and move
553 * to that state if so
555 if(!transition(s, mt)) {
556 ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
557 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_UNEXPECTED_MESSAGE);
558 return SUB_STATE_ERROR;
561 if (s->s3->tmp.message_size > max_message_size(s)) {
562 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
563 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
564 return SUB_STATE_ERROR;
567 st->read_state = READ_STATE_BODY;
570 case READ_STATE_BODY:
571 if (!SSL_IS_DTLS(s)) {
572 /* We already got this above for DTLS */
573 ret = tls_get_message_body(s, &len);
575 /* Could be non-blocking IO */
576 return SUB_STATE_ERROR;
581 if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
582 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
583 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
584 return SUB_STATE_ERROR;
586 ret = process_message(s, &pkt);
587 if (ret == MSG_PROCESS_ERROR) {
588 return SUB_STATE_ERROR;
591 if (ret == MSG_PROCESS_FINISHED_READING) {
592 if (SSL_IS_DTLS(s)) {
595 return SUB_STATE_FINISHED;
598 if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
599 st->read_state = READ_STATE_POST_PROCESS;
600 st->read_state_work = WORK_MORE_A;
602 st->read_state = READ_STATE_HEADER;
606 case READ_STATE_POST_PROCESS:
607 st->read_state_work = post_process_message(s, st->read_state_work);
608 switch(st->read_state_work) {
610 return SUB_STATE_ERROR;
612 case WORK_FINISHED_CONTINUE:
613 st->read_state = READ_STATE_HEADER;
616 case WORK_FINISHED_STOP:
617 if (SSL_IS_DTLS(s)) {
620 return SUB_STATE_FINISHED;
625 /* Shouldn't happen */
626 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
627 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
628 ossl_statem_set_error(s);
629 return SUB_STATE_ERROR;
635 * Send a previously constructed message to the peer.
637 static int statem_do_write(SSL *s)
639 OSSL_STATEM *st = &s->statem;
641 if (st->hand_state == TLS_ST_CW_CHANGE
642 || st->hand_state == TLS_ST_SW_CHANGE) {
644 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
646 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
648 return ssl_do_write(s);
653 * Initialise the MSG_FLOW_WRITING sub-state machine
655 static void init_write_state_machine(SSL *s)
657 OSSL_STATEM *st = &s->statem;
659 st->write_state = WRITE_STATE_TRANSITION;
663 * This function implements the sub-state machine when the message flow is in
664 * MSG_FLOW_WRITING. The valid sub-states and transitions are:
666 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
669 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
675 * | WRITE_STATE_POST_WORK
679 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
681 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
682 * sending of the message. This could result in an NBIO event occuring in
683 * which case control returns to the calling application. When this function
684 * is recalled we will resume in the same state where we left off.
686 * WRITE_STATE_SEND sends the message and performs any work to be done after
689 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
690 * message has been completed. As for WRITE_STATE_PRE_WORK this could also
691 * result in an NBIO event.
693 static SUB_STATE_RETURN write_state_machine(SSL *s)
695 OSSL_STATEM *st = &s->statem;
697 enum WRITE_TRAN (*transition)(SSL *s);
698 enum WORK_STATE (*pre_work)(SSL *s, enum WORK_STATE wst);
699 enum WORK_STATE (*post_work)(SSL *s, enum WORK_STATE wst);
700 int (*construct_message)(SSL *s);
701 void (*cb) (const SSL *ssl, int type, int val) = NULL;
703 cb = get_callback(s);
706 transition = server_write_transition;
707 pre_work = server_pre_work;
708 post_work = server_post_work;
709 construct_message = server_construct_message;
711 transition = client_write_transition;
712 pre_work = client_pre_work;
713 post_work = client_post_work;
714 construct_message = client_construct_message;
718 switch(st->write_state) {
719 case WRITE_STATE_TRANSITION:
721 /* Notify callback of an impending state change */
723 cb(s, SSL_CB_ACCEPT_LOOP, 1);
725 cb(s, SSL_CB_CONNECT_LOOP, 1);
727 switch(transition(s)) {
728 case WRITE_TRAN_CONTINUE:
729 st->write_state = WRITE_STATE_PRE_WORK;
730 st->write_state_work = WORK_MORE_A;
733 case WRITE_TRAN_FINISHED:
734 return SUB_STATE_FINISHED;
738 return SUB_STATE_ERROR;
742 case WRITE_STATE_PRE_WORK:
743 switch(st->write_state_work = pre_work(s, st->write_state_work)) {
745 return SUB_STATE_ERROR;
747 case WORK_FINISHED_CONTINUE:
748 st->write_state = WRITE_STATE_SEND;
751 case WORK_FINISHED_STOP:
752 return SUB_STATE_END_HANDSHAKE;
754 if(construct_message(s) == 0)
755 return SUB_STATE_ERROR;
759 case WRITE_STATE_SEND:
760 if (SSL_IS_DTLS(s) && st->use_timer) {
761 dtls1_start_timer(s);
763 ret = statem_do_write(s);
765 return SUB_STATE_ERROR;
767 st->write_state = WRITE_STATE_POST_WORK;
768 st->write_state_work = WORK_MORE_A;
771 case WRITE_STATE_POST_WORK:
772 switch(st->write_state_work = post_work(s, st->write_state_work)) {
774 return SUB_STATE_ERROR;
776 case WORK_FINISHED_CONTINUE:
777 st->write_state = WRITE_STATE_TRANSITION;
780 case WORK_FINISHED_STOP:
781 return SUB_STATE_END_HANDSHAKE;
786 return SUB_STATE_ERROR;
792 * Flush the write BIO
794 int statem_flush(SSL *s)
796 s->rwstate = SSL_WRITING;
797 if (BIO_flush(s->wbio) <= 0) {
800 s->rwstate = SSL_NOTHING;
806 * Called by the record layer to determine whether application data is
807 * allowed to be sent in the current handshake state or not.
810 * 1: Yes (application data allowed)
811 * 0: No (application data not allowed)
813 int ossl_statem_app_data_allowed(SSL *s)
815 OSSL_STATEM *st = &s->statem;
817 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
820 if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
825 * If we're a server and we haven't got as far as writing our
826 * ServerHello yet then we allow app data
828 if (st->hand_state == TLS_ST_BEFORE
829 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
833 * If we're a client and we haven't read the ServerHello yet then we
836 if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
843 #ifndef OPENSSL_NO_SCTP
845 * Set flag used by SCTP to determine whether we are in the read sock state
847 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
849 s->statem.in_sctp_read_sock = read_sock;
853 * Called by the record layer to determine whether we are in the read sock
857 * 1: Yes (we are in the read sock state)
858 * 0: No (we are not in the read sock state)
860 int statem_in_sctp_read_sock(SSL *s)
862 return s->statem.in_sctp_read_sock;