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)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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 */
98 enum SUB_STATE_RETURN {
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 enum SUB_STATE_RETURN read_state_machine(SSL *s);
110 static void init_write_state_machine(SSL *s);
111 static enum 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);
200 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
201 * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
202 * transitions are as follows:
204 * MSG_FLOW_UNINITED MSG_FLOW_RENEGOTIATE
206 * +-----------------------+
208 * MSG_FLOW_WRITING <---> MSG_FLOW_READING
216 * We may exit at any point due to an error or NBIO event. If an NBIO event
217 * occurs then we restart at the point we left off when we are recalled.
218 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
220 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
221 * into that state at any point in the event that an irrecoverable error occurs.
223 * Valid return values are:
227 static int state_machine(SSL *s, int server) {
229 unsigned long Time = (unsigned long)time(NULL);
230 void (*cb) (const SSL *ssl, int type, int val) = NULL;
231 STATEM *st = &s->statem;
235 if (st->state == MSG_FLOW_ERROR) {
236 /* Shouldn't have been called if we're already in the error state */
240 RAND_add(&Time, sizeof(Time), 0);
244 if (s->info_callback != NULL)
245 cb = s->info_callback;
246 else if (s->ctx->info_callback != NULL)
247 cb = s->ctx->info_callback;
250 if (!SSL_in_init(s) || SSL_in_before(s)) {
255 #ifndef OPENSSL_NO_SCTP
256 if (SSL_IS_DTLS(s)) {
258 * Notify SCTP BIO socket to enter handshake mode and prevent stream
259 * identifier other than 0. Will be ignored if no SCTP is used.
261 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
262 s->in_handshake, NULL);
266 #ifndef OPENSSL_NO_HEARTBEATS
268 * If we're awaiting a HeartbeatResponse, pretend we already got and
269 * don't await it anymore, because Heartbeats don't make sense during
272 if (s->tlsext_hb_pending) {
275 s->tlsext_hb_pending = 0;
280 /* Initialise state machine */
282 if (st->state == MSG_FLOW_RENEGOTIATE) {
285 s->ctx->stats.sess_connect_renegotiate++;
288 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
289 if (st->state == MSG_FLOW_UNINITED) {
290 st->hand_state = TLS_ST_BEFORE;
295 cb(s, SSL_CB_HANDSHAKE_START, 1);
297 if (SSL_IS_DTLS(s)) {
298 if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
300 || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
301 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
305 if ((s->version >> 8) != SSL3_VERSION_MAJOR
306 && s->version != TLS_ANY_VERSION) {
307 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
312 if (!SSL_IS_DTLS(s)) {
313 if (s->version != TLS_ANY_VERSION &&
314 !ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
315 SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
320 if (s->init_buf == NULL) {
321 if ((buf = BUF_MEM_new()) == NULL) {
324 if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
331 if (!ssl3_setup_buffers(s)) {
337 * Should have been reset by tls_process_finished, too.
339 s->s3->change_cipher_spec = 0;
341 if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
343 * Ok, we now need to push on a buffering BIO ...but not with
346 #ifndef OPENSSL_NO_SCTP
347 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
349 if (!ssl_init_wbio_buffer(s, server ? 1 : 0)) {
353 ssl3_init_finished_mac(s);
357 if (st->state != MSG_FLOW_RENEGOTIATE) {
358 s->ctx->stats.sess_accept++;
359 } else if (!s->s3->send_connection_binding &&
361 SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
363 * Server attempting to renegotiate with client that doesn't
364 * support secure renegotiation.
366 SSLerr(SSL_F_STATE_MACHINE,
367 SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
368 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
369 ossl_statem_set_error(s);
373 * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
376 s->ctx->stats.sess_accept_renegotiate++;
379 s->ctx->stats.sess_connect++;
381 /* mark client_random uninitialized */
382 memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
385 s->s3->tmp.cert_request = 0;
387 if (SSL_IS_DTLS(s)) {
392 st->state = MSG_FLOW_WRITING;
393 init_write_state_machine(s);
394 st->read_state_first_init = 1;
397 while(st->state != MSG_FLOW_FINISHED) {
398 if(st->state == MSG_FLOW_READING) {
399 ssret = read_state_machine(s);
400 if (ssret == SUB_STATE_FINISHED) {
401 st->state = MSG_FLOW_WRITING;
402 init_write_state_machine(s);
407 } else if (st->state == MSG_FLOW_WRITING) {
408 ssret = write_state_machine(s);
409 if (ssret == SUB_STATE_FINISHED) {
410 st->state = MSG_FLOW_READING;
411 init_read_state_machine(s);
412 } else if (ssret == SUB_STATE_END_HANDSHAKE) {
413 st->state = MSG_FLOW_FINISHED;
420 ossl_statem_set_error(s);
425 st->state = MSG_FLOW_UNINITED;
431 #ifndef OPENSSL_NO_SCTP
432 if (SSL_IS_DTLS(s)) {
434 * Notify SCTP BIO socket to leave handshake mode and allow stream
435 * identifier other than 0. Will be ignored if no SCTP is used.
437 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
438 s->in_handshake, NULL);
445 cb(s, SSL_CB_ACCEPT_EXIT, ret);
447 cb(s, SSL_CB_CONNECT_EXIT, ret);
453 * Initialise the MSG_FLOW_READING sub-state machine
455 static void init_read_state_machine(SSL *s)
457 STATEM *st = &s->statem;
459 st->read_state = READ_STATE_HEADER;
463 * This function implements the sub-state machine when the message flow is in
464 * MSG_FLOW_READING. The valid sub-states and transitions are:
466 * READ_STATE_HEADER <--+<-------------+
469 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
471 * +----------------------------+
473 * [SUB_STATE_FINISHED]
475 * READ_STATE_HEADER has the responsibility for reading in the message header
476 * and transitioning the state of the handshake state machine.
478 * READ_STATE_BODY reads in the rest of the message and then subsequently
481 * READ_STATE_POST_PROCESS is an optional step that may occur if some post
482 * processing activity performed on the message may block.
484 * Any of the above states could result in an NBIO event occuring in which case
485 * control returns to the calling application. When this function is recalled we
486 * will resume in the same state where we left off.
488 static enum SUB_STATE_RETURN read_state_machine(SSL *s) {
489 STATEM *st = &s->statem;
492 int (*transition)(SSL *s, int mt);
494 enum MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
495 enum WORK_STATE (*post_process_message)(SSL *s, enum WORK_STATE wst);
496 unsigned long (*max_message_size)(SSL *s);
497 void (*cb) (const SSL *ssl, int type, int val) = NULL;
499 if (s->info_callback != NULL)
500 cb = s->info_callback;
501 else if (s->ctx->info_callback != NULL)
502 cb = s->ctx->info_callback;
505 transition = server_read_transition;
506 process_message = server_process_message;
507 max_message_size = server_max_message_size;
508 post_process_message = server_post_process_message;
510 transition = client_read_transition;
511 process_message = client_process_message;
512 max_message_size = client_max_message_size;
513 post_process_message = client_post_process_message;
516 if (st->read_state_first_init) {
518 st->read_state_first_init = 0;
522 switch(st->read_state) {
523 case READ_STATE_HEADER:
525 /* Get the state the peer wants to move to */
526 if (SSL_IS_DTLS(s)) {
528 * In DTLS we get the whole message in one go - header and body
530 ret = dtls_get_message(s, &mt, &len);
532 ret = tls_get_message_header(s, &mt);
536 /* Could be non-blocking IO */
537 return SUB_STATE_ERROR;
541 /* Notify callback of an impending state change */
543 cb(s, SSL_CB_ACCEPT_LOOP, 1);
545 cb(s, SSL_CB_CONNECT_LOOP, 1);
548 * Validate that we are allowed to move to the new state and move
549 * to that state if so
551 if(!transition(s, mt)) {
552 ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
553 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_UNEXPECTED_MESSAGE);
554 return SUB_STATE_ERROR;
557 if (s->s3->tmp.message_size > max_message_size(s)) {
558 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
559 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
560 return SUB_STATE_ERROR;
563 st->read_state = READ_STATE_BODY;
566 case READ_STATE_BODY:
567 if (!SSL_IS_DTLS(s)) {
568 /* We already got this above for DTLS */
569 ret = tls_get_message_body(s, &len);
571 /* Could be non-blocking IO */
572 return SUB_STATE_ERROR;
577 if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
578 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
579 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
580 return SUB_STATE_ERROR;
582 ret = process_message(s, &pkt);
583 if (ret == MSG_PROCESS_ERROR) {
584 return SUB_STATE_ERROR;
587 if (ret == MSG_PROCESS_FINISHED_READING) {
588 if (SSL_IS_DTLS(s)) {
591 return SUB_STATE_FINISHED;
594 if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
595 st->read_state = READ_STATE_POST_PROCESS;
596 st->read_state_work = WORK_MORE_A;
598 st->read_state = READ_STATE_HEADER;
602 case READ_STATE_POST_PROCESS:
603 st->read_state_work = post_process_message(s, st->read_state_work);
604 switch(st->read_state_work) {
606 return SUB_STATE_ERROR;
608 case WORK_FINISHED_CONTINUE:
609 st->read_state = READ_STATE_HEADER;
612 case WORK_FINISHED_STOP:
613 if (SSL_IS_DTLS(s)) {
616 return SUB_STATE_FINISHED;
621 /* Shouldn't happen */
622 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
623 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
624 ossl_statem_set_error(s);
625 return SUB_STATE_ERROR;
631 * Send a previously constructed message to the peer.
633 static int statem_do_write(SSL *s)
635 STATEM *st = &s->statem;
637 if (st->hand_state == TLS_ST_CW_CHANGE
638 || st->hand_state == TLS_ST_SW_CHANGE) {
640 return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
642 return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
644 return ssl_do_write(s);
649 * Initialise the MSG_FLOW_WRITING sub-state machine
651 static void init_write_state_machine(SSL *s)
653 STATEM *st = &s->statem;
655 st->write_state = WRITE_STATE_TRANSITION;
659 * This function implements the sub-state machine when the message flow is in
660 * MSG_FLOW_WRITING. The valid sub-states and transitions are:
662 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
665 * | WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
671 * | WRITE_STATE_POST_WORK
675 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
677 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
678 * sending of the message. This could result in an NBIO event occuring in
679 * which case control returns to the calling application. When this function
680 * is recalled we will resume in the same state where we left off.
682 * WRITE_STATE_SEND sends the message and performs any work to be done after
685 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
686 * message has been completed. As for WRITE_STATE_PRE_WORK this could also
687 * result in an NBIO event.
689 static enum SUB_STATE_RETURN write_state_machine(SSL *s)
691 STATEM *st = &s->statem;
693 enum WRITE_TRAN (*transition)(SSL *s);
694 enum WORK_STATE (*pre_work)(SSL *s, enum WORK_STATE wst);
695 enum WORK_STATE (*post_work)(SSL *s, enum WORK_STATE wst);
696 int (*construct_message)(SSL *s);
697 void (*cb) (const SSL *ssl, int type, int val) = NULL;
699 if (s->info_callback != NULL)
700 cb = s->info_callback;
701 else if (s->ctx->info_callback != NULL)
702 cb = s->ctx->info_callback;
705 transition = server_write_transition;
706 pre_work = server_pre_work;
707 post_work = server_post_work;
708 construct_message = server_construct_message;
710 transition = client_write_transition;
711 pre_work = client_pre_work;
712 post_work = client_post_work;
713 construct_message = client_construct_message;
717 switch(st->write_state) {
718 case WRITE_STATE_TRANSITION:
720 /* Notify callback of an impending state change */
722 cb(s, SSL_CB_ACCEPT_LOOP, 1);
724 cb(s, SSL_CB_CONNECT_LOOP, 1);
726 switch(transition(s)) {
727 case WRITE_TRAN_CONTINUE:
728 st->write_state = WRITE_STATE_PRE_WORK;
729 st->write_state_work = WORK_MORE_A;
732 case WRITE_TRAN_FINISHED:
733 return SUB_STATE_FINISHED;
737 return SUB_STATE_ERROR;
741 case WRITE_STATE_PRE_WORK:
742 switch(st->write_state_work = pre_work(s, st->write_state_work)) {
744 return SUB_STATE_ERROR;
746 case WORK_FINISHED_CONTINUE:
747 st->write_state = WRITE_STATE_SEND;
750 case WORK_FINISHED_STOP:
751 return SUB_STATE_END_HANDSHAKE;
753 if(construct_message(s) == 0)
754 return SUB_STATE_ERROR;
758 case WRITE_STATE_SEND:
759 if (SSL_IS_DTLS(s) && st->use_timer) {
760 dtls1_start_timer(s);
762 ret = statem_do_write(s);
764 return SUB_STATE_ERROR;
766 st->write_state = WRITE_STATE_POST_WORK;
767 st->write_state_work = WORK_MORE_A;
770 case WRITE_STATE_POST_WORK:
771 switch(st->write_state_work = post_work(s, st->write_state_work)) {
773 return SUB_STATE_ERROR;
775 case WORK_FINISHED_CONTINUE:
776 st->write_state = WRITE_STATE_TRANSITION;
779 case WORK_FINISHED_STOP:
780 return SUB_STATE_END_HANDSHAKE;
785 return SUB_STATE_ERROR;
791 * Flush the write BIO
793 int statem_flush(SSL *s)
795 s->rwstate = SSL_WRITING;
796 if (BIO_flush(s->wbio) <= 0) {
799 s->rwstate = SSL_NOTHING;
805 * Called by the record layer to determine whether application data is
806 * allowed to be sent in the current handshake state or not.
809 * 1: Yes (application data allowed)
810 * 0: No (application data not allowed)
812 int ossl_statem_app_data_allowed(SSL *s)
814 STATEM *st = &s->statem;
816 if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
819 if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
824 * If we're a server and we haven't got as far as writing our
825 * ServerHello yet then we allow app data
827 if (st->hand_state == TLS_ST_BEFORE
828 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
832 * If we're a client and we haven't read the ServerHello yet then we
835 if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
842 #ifndef OPENSSL_NO_SCTP
844 * Set flag used by SCTP to determine whether we are in the read sock state
846 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
848 s->statem.in_sctp_read_sock = read_sock;
852 * Called by the record layer to determine whether we are in the read sock
856 * 1: Yes (we are in the read sock state)
857 * 0: No (we are not in the read sock state)
859 int statem_in_sctp_read_sock(SSL *s)
861 return s->statem.in_sctp_read_sock;