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13e81fc971
boringssl/ssl/d1_clnt.c
David Benjamin 13e81fc971 Fix DTLS asynchronous write handling. 
Although the DTLS transport layer logic drops failed writes on the floor, it is
actually set up to work correctly. If an SSL_write fails at the transport,
dropping the buffer is fine. Arguably it works better than in TLS because we
don't have the weird "half-committed to data" behavior. Likewise, the handshake
keeps track of how far its gotten and resumes the message at the right point.

This broke when the buffering logic was rewritten because I didn't understand
what the DTLS code was doing. The one thing that doesn't work as one might
expect is non-fatal write errors during rexmit are not recoverable. The next
timeout must fire before we try again.

This code is quite badly sprinkled in here, so add tests to guard it against
future turbulence. Because of the rexmit issues, the tests need some hacks
around calls which may trigger them. It also changes the Go DTLS implementation
from being completely strict about sequence numbers to only requiring they be
monotonic.

The tests also revealed another bug. This one seems to be upstream's fault, not
mine. The logic to reset the handshake hash on the second ClientHello (in the
HelloVerifyRequest case) was a little overenthusiastic and breaks if the
ClientHello took multiple tries to send.

Change-Id: I9b38b93fff7ae62faf8e36c4beaf848850b3f4b9
Reviewed-on: https://boringssl-review.googlesource.com/6417
Reviewed-by: Adam Langley <agl@google.com>
2015-11-02 23:16:22 +00:00

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/*
* DTLS implementation written by Nagendra Modadugu
* (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
*/
/* ====================================================================
* Copyright (c) 1999-2007 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
#include <openssl/ssl.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/buf.h>
#include <openssl/dh.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <openssl/md5.h>
#include <openssl/mem.h>
#include <openssl/obj.h>
#include <openssl/rand.h>
#include "internal.h"
static int dtls1_get_hello_verify(SSL *s);
int dtls1_connect(SSL *s) {
BUF_MEM *buf = NULL;
void (*cb)(const SSL *ssl, int type, int value) = NULL;
int ret = -1;
int new_state, state, skip = 0;
assert(s->handshake_func == dtls1_connect);
assert(!s->server);
assert(SSL_IS_DTLS(s));
ERR_clear_error();
ERR_clear_system_error();
if (s->info_callback != NULL) {
cb = s->info_callback;
} else if (s->ctx->info_callback != NULL) {
cb = s->ctx->info_callback;
}
s->in_handshake++;
for (;;) {
state = s->state;
switch (s->state) {
case SSL_ST_CONNECT:
if (cb != NULL) {
cb(s, SSL_CB_HANDSHAKE_START, 1);
}
if (s->init_buf == NULL) {
buf = BUF_MEM_new();
if (buf == NULL ||
!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
ret = -1;
goto end;
}
s->init_buf = buf;
buf = NULL;
}
if (!ssl_init_wbio_buffer(s, 0)) {
ret = -1;
goto end;
}
/* don't push the buffering BIO quite yet */
s->state = SSL3_ST_CW_CLNT_HELLO_A;
s->init_num = 0;
s->d1->send_cookie = 0;
s->hit = 0;
break;
case SSL3_ST_CW_CLNT_HELLO_A:
case SSL3_ST_CW_CLNT_HELLO_B:
s->shutdown = 0;
dtls1_start_timer(s);
ret = ssl3_send_client_hello(s);
if (ret <= 0) {
goto end;
}
if (s->d1->send_cookie) {
s->state = SSL3_ST_CW_FLUSH;
s->s3->tmp.next_state = SSL3_ST_CR_SRVR_HELLO_A;
} else {
s->state = DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A;
}
s->init_num = 0;
/* turn on buffering for the next lot of output */
if (s->bbio != s->wbio) {
s->wbio = BIO_push(s->bbio, s->wbio);
}
break;
case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A:
case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B:
ret = dtls1_get_hello_verify(s);
if (ret <= 0) {
goto end;
}
if (s->d1->send_cookie) {
/* start again, with a cookie */
dtls1_stop_timer(s);
s->state = SSL3_ST_CW_CLNT_HELLO_A;
} else {
s->state = SSL3_ST_CR_SRVR_HELLO_A;
}
s->init_num = 0;
break;
case SSL3_ST_CR_SRVR_HELLO_A:
case SSL3_ST_CR_SRVR_HELLO_B:
ret = ssl3_get_server_hello(s);
if (ret <= 0) {
goto end;
}
if (s->hit) {
s->state = SSL3_ST_CR_FINISHED_A;
if (s->tlsext_ticket_expected) {
/* receive renewed session ticket */
s->state = SSL3_ST_CR_SESSION_TICKET_A;
}
} else {
s->state = SSL3_ST_CR_CERT_A;
}
s->init_num = 0;
break;
case SSL3_ST_CR_CERT_A:
case SSL3_ST_CR_CERT_B:
if (ssl_cipher_has_server_public_key(s->s3->tmp.new_cipher)) {
ret = ssl3_get_server_certificate(s);
if (ret <= 0) {
goto end;
}
if (s->s3->tmp.certificate_status_expected) {
s->state = SSL3_ST_CR_CERT_STATUS_A;
} else {
s->state = SSL3_ST_VERIFY_SERVER_CERT;
}
} else {
skip = 1;
s->state = SSL3_ST_CR_KEY_EXCH_A;
}
s->init_num = 0;
break;
case SSL3_ST_VERIFY_SERVER_CERT:
ret = ssl3_verify_server_cert(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CR_KEY_EXCH_A;
s->init_num = 0;
break;
case SSL3_ST_CR_KEY_EXCH_A:
case SSL3_ST_CR_KEY_EXCH_B:
ret = ssl3_get_server_key_exchange(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CR_CERT_REQ_A;
s->init_num = 0;
break;
case SSL3_ST_CR_CERT_REQ_A:
case SSL3_ST_CR_CERT_REQ_B:
ret = ssl3_get_certificate_request(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CR_SRVR_DONE_A;
s->init_num = 0;
break;
case SSL3_ST_CR_SRVR_DONE_A:
case SSL3_ST_CR_SRVR_DONE_B:
ret = ssl3_get_server_done(s);
if (ret <= 0) {
goto end;
}
dtls1_stop_timer(s);
if (s->s3->tmp.cert_req) {
s->s3->tmp.next_state = SSL3_ST_CW_CERT_A;
} else {
s->s3->tmp.next_state = SSL3_ST_CW_KEY_EXCH_A;
}
s->init_num = 0;
s->state = s->s3->tmp.next_state;
break;
case SSL3_ST_CW_CERT_A:
case SSL3_ST_CW_CERT_B:
case SSL3_ST_CW_CERT_C:
case SSL3_ST_CW_CERT_D:
dtls1_start_timer(s);
ret = ssl3_send_client_certificate(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CW_KEY_EXCH_A;
s->init_num = 0;
break;
case SSL3_ST_CW_KEY_EXCH_A:
case SSL3_ST_CW_KEY_EXCH_B:
dtls1_start_timer(s);
ret = ssl3_send_client_key_exchange(s);
if (ret <= 0) {
goto end;
}
/* For TLS, cert_req is set to 2, so a cert chain
* of nothing is sent, but no verify packet is sent */
if (s->s3->tmp.cert_req == 1) {
s->state = SSL3_ST_CW_CERT_VRFY_A;
} else {
s->state = SSL3_ST_CW_CHANGE_A;
s->s3->change_cipher_spec = 0;
}
s->init_num = 0;
break;
case SSL3_ST_CW_CERT_VRFY_A:
case SSL3_ST_CW_CERT_VRFY_B:
dtls1_start_timer(s);
ret = ssl3_send_cert_verify(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CW_CHANGE_A;
s->init_num = 0;
s->s3->change_cipher_spec = 0;
break;
case SSL3_ST_CW_CHANGE_A:
case SSL3_ST_CW_CHANGE_B:
if (!s->hit) {
dtls1_start_timer(s);
}
ret = dtls1_send_change_cipher_spec(s, SSL3_ST_CW_CHANGE_A,
SSL3_ST_CW_CHANGE_B);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CW_FINISHED_A;
s->init_num = 0;
s->session->cipher = s->s3->tmp.new_cipher;
if (!s->enc_method->setup_key_block(s) ||
!s->enc_method->change_cipher_state(
s, SSL3_CHANGE_CIPHER_CLIENT_WRITE)) {
ret = -1;
goto end;
}
dtls1_reset_seq_numbers(s, SSL3_CC_WRITE);
break;
case SSL3_ST_CW_FINISHED_A:
case SSL3_ST_CW_FINISHED_B:
if (!s->hit) {
dtls1_start_timer(s);
}
ret =
ssl3_send_finished(s, SSL3_ST_CW_FINISHED_A, SSL3_ST_CW_FINISHED_B,
s->enc_method->client_finished_label,
s->enc_method->client_finished_label_len);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CW_FLUSH;
if (s->hit) {
s->s3->tmp.next_state = SSL_ST_OK;
} else {
/* Allow NewSessionTicket if ticket expected */
if (s->tlsext_ticket_expected) {
s->s3->tmp.next_state = SSL3_ST_CR_SESSION_TICKET_A;
} else {
s->s3->tmp.next_state = SSL3_ST_CR_FINISHED_A;
}
}
s->init_num = 0;
break;
case SSL3_ST_CR_SESSION_TICKET_A:
case SSL3_ST_CR_SESSION_TICKET_B:
ret = ssl3_get_new_session_ticket(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_CR_FINISHED_A;
s->init_num = 0;
break;
case SSL3_ST_CR_CERT_STATUS_A:
case SSL3_ST_CR_CERT_STATUS_B:
ret = ssl3_get_cert_status(s);
if (ret <= 0) {
goto end;
}
s->state = SSL3_ST_VERIFY_SERVER_CERT;
s->init_num = 0;
break;
case SSL3_ST_CR_FINISHED_A:
case SSL3_ST_CR_FINISHED_B:
s->d1->change_cipher_spec_ok = 1;
ret =
ssl3_get_finished(s, SSL3_ST_CR_FINISHED_A, SSL3_ST_CR_FINISHED_B);
if (ret <= 0) {
goto end;
}
dtls1_stop_timer(s);
if (s->hit) {
s->state = SSL3_ST_CW_CHANGE_A;
} else {
s->state = SSL_ST_OK;
}
s->init_num = 0;
break;
case SSL3_ST_CW_FLUSH:
s->rwstate = SSL_WRITING;
if (BIO_flush(s->wbio) <= 0) {
ret = -1;
goto end;
}
s->rwstate = SSL_NOTHING;
s->state = s->s3->tmp.next_state;
break;
case SSL_ST_OK:
/* clean a few things up */
ssl3_cleanup_key_block(s);
/* Remove write buffering now. */
ssl_free_wbio_buffer(s);
s->init_num = 0;
s->s3->initial_handshake_complete = 1;
ssl_update_cache(s, SSL_SESS_CACHE_CLIENT);
ret = 1;
if (cb != NULL) {
cb(s, SSL_CB_HANDSHAKE_DONE, 1);
}
/* done with handshaking */
s->d1->handshake_read_seq = 0;
s->d1->next_handshake_write_seq = 0;
goto end;
default:
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_STATE);
ret = -1;
goto end;
}
/* did we do anything? */
if (!s->s3->tmp.reuse_message && !skip) {
if ((cb != NULL) && (s->state != state)) {
new_state = s->state;
s->state = state;
cb(s, SSL_CB_CONNECT_LOOP, 1);
s->state = new_state;
}
}
skip = 0;
}
end:
s->in_handshake--;
BUF_MEM_free(buf);
if (cb != NULL) {
cb(s, SSL_CB_CONNECT_EXIT, ret);
}
return ret;
}
static int dtls1_get_hello_verify(SSL *s) {
long n;
int al, ok = 0;
CBS hello_verify_request, cookie;
uint16_t server_version;
n = s->method->ssl_get_message(
s, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B,
-1,
/* Use the same maximum size as ssl3_get_server_hello. */
20000, ssl_hash_message, &ok);
if (!ok) {
return n;
}
if (s->s3->tmp.message_type != DTLS1_MT_HELLO_VERIFY_REQUEST) {
s->d1->send_cookie = 0;
s->s3->tmp.reuse_message = 1;
return 1;
}
CBS_init(&hello_verify_request, s->init_msg, n);
if (!CBS_get_u16(&hello_verify_request, &server_version) ||
!CBS_get_u8_length_prefixed(&hello_verify_request, &cookie) ||
CBS_len(&hello_verify_request) != 0) {
al = SSL_AD_DECODE_ERROR;
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
goto f_err;
}
if (CBS_len(&cookie) > sizeof(s->d1->cookie)) {
al = SSL_AD_ILLEGAL_PARAMETER;
goto f_err;
}
memcpy(s->d1->cookie, CBS_data(&cookie), CBS_len(&cookie));
s->d1->cookie_len = CBS_len(&cookie);
s->d1->send_cookie = 1;
return 1;
f_err:
ssl3_send_alert(s, SSL3_AL_FATAL, al);
return -1;
}
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