generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
openssl/ssl/s23_srvr.c
Matt Caswell 32ec41539b Server side version negotiation rewrite 
This commit changes the way that we do server side protocol version
negotiation. Previously we had a whole set of code that had an "up front"
state machine dedicated to the negotiating the protocol version. This adds
significant complexity to the state machine. Historically the justification
for doing this was the support of SSLv2 which works quite differently to
SSLv3+. However, we have now removed support for SSLv2 so there is little
reason to maintain this complexity.

The one slight difficulty is that, although we no longer support SSLv2, we
do still support an SSLv3+ ClientHello in an SSLv2 backward compatible
ClientHello format. This is generally only used by legacy clients. This
commit adds support within the SSLv3 code for these legacy format
ClientHellos.

Server side version negotiation now works in much the same was as DTLS,
i.e. we introduce the concept of TLS_ANY_VERSION. If s->version is set to
that then when a ClientHello is received it will work out the most
appropriate version to respond with. Also, SSLv23_method and
SSLv23_server_method have been replaced with TLS_method and
TLS_server_method respectively. The old SSLv23* names still exist as
macros pointing at the new name, although they are deprecated.

Subsequent commits will look at client side version negotiation, as well of
removal of the old s23* code.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
2015-05-16 09:19:56 +01:00

583 lines
20 KiB
C
Raw Blame History

/* ssl/s23_srvr.c */
/* 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.]
*/
/* ====================================================================
* Copyright (c) 1998-2006 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).
*
*/
#include <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
static const SSL_METHOD *ssl23_get_server_method(int ver);
int ssl23_get_client_hello(SSL *s);
static const SSL_METHOD *ssl23_get_server_method(int ver)
{
#ifndef OPENSSL_NO_SSL3
if (ver == SSL3_VERSION)
return (SSLv3_server_method());
#endif
if (ver == TLS1_VERSION)
return (TLSv1_server_method());
else if (ver == TLS1_1_VERSION)
return (TLSv1_1_server_method());
else if (ver == TLS1_2_VERSION)
return (TLSv1_2_server_method());
else
return (NULL);
}
int ssl23_accept(SSL *s)
{
BUF_MEM *buf;
unsigned long Time = (unsigned long)time(NULL);
void (*cb) (const SSL *ssl, int type, int val) = NULL;
int ret = -1;
int new_state, state;
RAND_add(&Time, sizeof(Time), 0);
ERR_clear_error();
clear_sys_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++;
if (!SSL_in_init(s) || SSL_in_before(s)) {
if (!SSL_clear(s))
return -1;
}
for (;;) {
state = s->state;
switch (s->state) {
case SSL_ST_BEFORE:
case SSL_ST_ACCEPT:
case SSL_ST_BEFORE | SSL_ST_ACCEPT:
case SSL_ST_OK | SSL_ST_ACCEPT:
s->server = 1;
if (cb != NULL)
cb(s, SSL_CB_HANDSHAKE_START, 1);
/* s->version=SSL3_VERSION; */
s->type = SSL_ST_ACCEPT;
if (s->init_buf == NULL) {
if ((buf = BUF_MEM_new()) == NULL) {
ret = -1;
goto end;
}
if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
BUF_MEM_free(buf);
ret = -1;
goto end;
}
s->init_buf = buf;
}
ssl3_init_finished_mac(s);
s->state = SSL23_ST_SR_CLNT_HELLO_A;
s->ctx->stats.sess_accept++;
s->init_num = 0;
break;
case SSL23_ST_SR_CLNT_HELLO_A:
case SSL23_ST_SR_CLNT_HELLO_B:
s->shutdown = 0;
ret = ssl23_get_client_hello(s);
if (ret >= 0)
cb = NULL;
goto end;
/* break; */
default:
SSLerr(SSL_F_SSL23_ACCEPT, SSL_R_UNKNOWN_STATE);
ret = -1;
goto end;
/* break; */
}
if ((cb != NULL) && (s->state != state)) {
new_state = s->state;
s->state = state;
cb(s, SSL_CB_ACCEPT_LOOP, 1);
s->state = new_state;
}
}
end:
s->in_handshake--;
if (cb != NULL)
cb(s, SSL_CB_ACCEPT_EXIT, ret);
return (ret);
}
int ssl23_get_client_hello(SSL *s)
{
/*-
* Request this many bytes in initial read.
* We can detect SSL 3.0/TLS 1.0 Client Hellos
* ('type == 3') correctly only when the following
* is in a single record, which is not guaranteed by
* the protocol specification:
* Byte Content
* 0 type \
* 1/2 version > record header
* 3/4 length /
* 5 msg_type \
* 6-8 length > Client Hello message
* 9/10 client_version /
*/
unsigned char buf_space[11];
unsigned char *buf = &(buf_space[0]);
unsigned char *p, *d, *d_len, *dd;
unsigned int i;
unsigned int csl, sil, cl;
int n = 0, j;
int type = 0;
int v[2];
if (s->state == SSL23_ST_SR_CLNT_HELLO_A) {
/* read the initial header */
v[0] = v[1] = 0;
if (!ssl3_setup_buffers(s))
goto err;
n = ssl23_read_bytes(s, sizeof buf_space);
if (n != sizeof buf_space)
return (n); /* n == -1 || n == 0 */
p = RECORD_LAYER_get_packet(&s->rlayer);
memcpy(buf, p, n);
if ((p[0] & 0x80) && (p[2] == SSL2_MT_CLIENT_HELLO)) {
/*
* SSLv2 header
*/
if ((p[3] == 0x00) && (p[4] == 0x02)) {
v[0] = p[3];
v[1] = p[4];
/* SSLv2 */
} else if (p[3] == SSL3_VERSION_MAJOR) {
v[0] = p[3];
v[1] = p[4];
/* SSLv3/TLSv1 */
if (p[4] >= TLS1_VERSION_MINOR) {
if (p[4] >= TLS1_2_VERSION_MINOR &&
!(s->options & SSL_OP_NO_TLSv1_2)) {
s->version = TLS1_2_VERSION;
s->state = SSL23_ST_SR_CLNT_HELLO_B;
} else if (p[4] >= TLS1_1_VERSION_MINOR &&
!(s->options & SSL_OP_NO_TLSv1_1)) {
s->version = TLS1_1_VERSION;
/*
* type=2;
*//*
* done later to survive restarts
*/
s->state = SSL23_ST_SR_CLNT_HELLO_B;
} else if (!(s->options & SSL_OP_NO_TLSv1)) {
s->version = TLS1_VERSION;
/*
* type=2;
*//*
* done later to survive restarts
*/
s->state = SSL23_ST_SR_CLNT_HELLO_B;
} else if (!(s->options & SSL_OP_NO_SSLv3)) {
s->version = SSL3_VERSION;
/* type=2; */
s->state = SSL23_ST_SR_CLNT_HELLO_B;
}
} else if (!(s->options & SSL_OP_NO_SSLv3)) {
s->version = SSL3_VERSION;
/* type=2; */
s->state = SSL23_ST_SR_CLNT_HELLO_B;
}
}
}
/* p[4] < 5 ... silly record length? */
else if ((p[0] == SSL3_RT_HANDSHAKE) &&
(p[1] == SSL3_VERSION_MAJOR) &&
(p[5] == SSL3_MT_CLIENT_HELLO) && ((p[3] == 0 && p[4] < 5)
|| (p[9] >= p[1]))) {
/*
* SSLv3 or tls1 header
*/
v[0] = p[1]; /* major version (= SSL3_VERSION_MAJOR) */
/*
* We must look at client_version inside the Client Hello message
* to get the correct minor version. However if we have only a
* pathologically small fragment of the Client Hello message, this
* would be difficult, and we'd have to read more records to find
* out. No known SSL 3.0 client fragments ClientHello like this,
* so we simply reject such connections to avoid protocol version
* downgrade attacks.
*/
if (p[3] == 0 && p[4] < 6) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_RECORD_TOO_SMALL);
goto err;
}
/*
* if major version number > 3 set minor to a value which will
* use the highest version 3 we support. If TLS 2.0 ever appears
* we will need to revise this....
*/
if (p[9] > SSL3_VERSION_MAJOR)
v[1] = 0xff;
else
v[1] = p[10]; /* minor version according to client_version */
if (v[1] >= TLS1_VERSION_MINOR) {
if (v[1] >= TLS1_2_VERSION_MINOR &&
!(s->options & SSL_OP_NO_TLSv1_2)) {
s->version = TLS1_2_VERSION;
type = 3;
} else if (v[1] >= TLS1_1_VERSION_MINOR &&
!(s->options & SSL_OP_NO_TLSv1_1)) {
s->version = TLS1_1_VERSION;
type = 3;
} else if (!(s->options & SSL_OP_NO_TLSv1)) {
s->version = TLS1_VERSION;
type = 3;
} else if (!(s->options & SSL_OP_NO_SSLv3)) {
s->version = SSL3_VERSION;
type = 3;
}
} else {
/* client requests SSL 3.0 */
if (!(s->options & SSL_OP_NO_SSLv3)) {
s->version = SSL3_VERSION;
type = 3;
} else if (!(s->options & SSL_OP_NO_TLSv1)) {
/*
* we won't be able to use TLS of course, but this will
* send an appropriate alert
*/
s->version = TLS1_VERSION;
type = 3;
}
}
} else if ((strncmp("GET ", (char *)p, 4) == 0) ||
(strncmp("POST ", (char *)p, 5) == 0) ||
(strncmp("HEAD ", (char *)p, 5) == 0) ||
(strncmp("PUT ", (char *)p, 4) == 0)) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_HTTP_REQUEST);
goto err;
} else if (strncmp("CONNECT", (char *)p, 7) == 0) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_HTTPS_PROXY_REQUEST);
goto err;
}
}
/* ensure that TLS_MAX_VERSION is up-to-date */
OPENSSL_assert(s->version <= TLS_MAX_VERSION);
if (s->version < TLS1_2_VERSION && tls1_suiteb(s)) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
SSL_R_ONLY_TLS_1_2_ALLOWED_IN_SUITEB_MODE);
goto err;
}
if (FIPS_mode() && (s->version < TLS1_VERSION)) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
SSL_R_ONLY_TLS_ALLOWED_IN_FIPS_MODE);
goto err;
}
if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_VERSION_TOO_LOW);
goto err;
}
if (s->state == SSL23_ST_SR_CLNT_HELLO_B) {
/*
* we have SSLv3/TLSv1 in an SSLv2 header (other cases skip this
* state)
*/
type = 2;
p = RECORD_LAYER_get_packet(&s->rlayer);
v[0] = p[3]; /* == SSL3_VERSION_MAJOR */
v[1] = p[4];
/*-
* An SSLv3/TLSv1 backwards-compatible CLIENT-HELLO in an SSLv2
* header is sent directly on the wire, not wrapped as a TLS
* record. It's format is:
* Byte Content
* 0-1 msg_length
* 2 msg_type
* 3-4 version
* 5-6 cipher_spec_length
* 7-8 session_id_length
* 9-10 challenge_length
* ... ...
*/
n = ((p[0] & 0x7f) << 8) | p[1];
if (n > (1024 * 4)) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_RECORD_TOO_LARGE);
goto err;
}
if (n < 9) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
SSL_R_RECORD_LENGTH_MISMATCH);
goto err;
}
j = ssl23_read_bytes(s, n + 2);
/*
* We previously read 11 bytes, so if j > 0, we must have j == n+2 ==
* s->packet_length. We have at least 11 valid packet bytes.
*/
if (j <= 0)
return (j);
ssl3_finish_mac(s, RECORD_LAYER_get_packet(&s->rlayer) + 2,
RECORD_LAYER_get_packet_length(&s->rlayer) - 2);
/* CLIENT-HELLO */
if (s->msg_callback)
s->msg_callback(0, SSL2_VERSION, 0,
RECORD_LAYER_get_packet(&s->rlayer) + 2,
RECORD_LAYER_get_packet_length(&s->rlayer) - 2, s,
s->msg_callback_arg);
p = RECORD_LAYER_get_packet(&s->rlayer);
p += 5;
n2s(p, csl);
n2s(p, sil);
n2s(p, cl);
d = (unsigned char *)s->init_buf->data;
if ((csl + sil + cl + 11)
!= RECORD_LAYER_get_packet_length(&s->rlayer)) {
/* We can't have TLS
* extensions in SSL
* 2.0 format *
* Client Hello, can
* we? Error
* condition should
* be * '>'
* otherweise */
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO,
SSL_R_RECORD_LENGTH_MISMATCH);
goto err;
}
/* record header: msg_type ... */
*(d++) = SSL3_MT_CLIENT_HELLO;
/* ... and length (actual value will be written later) */
d_len = d;
d += 3;
/* client_version */
*(d++) = SSL3_VERSION_MAJOR; /* == v[0] */
*(d++) = v[1];
/* lets populate the random area */
/* get the challenge_length */
i = (cl > SSL3_RANDOM_SIZE) ? SSL3_RANDOM_SIZE : cl;
memset(d, 0, SSL3_RANDOM_SIZE);
memcpy(&(d[SSL3_RANDOM_SIZE - i]), &(p[csl + sil]), i);
d += SSL3_RANDOM_SIZE;
/* no session-id reuse */
*(d++) = 0;
/* ciphers */
j = 0;
dd = d;
d += 2;
for (i = 0; i < csl; i += 3) {
if (p[i] != 0)
continue;
*(d++) = p[i + 1];
*(d++) = p[i + 2];
j += 2;
}
s2n(j, dd);
/* COMPRESSION */
*(d++) = 1;
*(d++) = 0;
#if 0
/* copy any remaining data with may be extensions */
p = p + csl + sil + cl;
while (p < s->packet + s->packet_length) {
*(d++) = *(p++);
}
#endif
i = (d - (unsigned char *)s->init_buf->data) - 4;
l2n3((long)i, d_len);
/* get the data reused from the init_buf */
s->s3->tmp.reuse_message = 1;
s->s3->tmp.message_type = SSL3_MT_CLIENT_HELLO;
s->s3->tmp.message_size = i;
}
/* imaginary new state (for program structure): */
/* s->state = SSL23_SR_CLNT_HELLO_C */
if ((type == 2) || (type == 3)) {
/*
* we have SSLv3/TLSv1 (type 2: SSL2 style, type 3: SSL3/TLS style)
*/
const SSL_METHOD *new_method;
new_method = ssl23_get_server_method(s->version);
if (new_method == NULL) {
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_UNSUPPORTED_PROTOCOL);
goto err;
}
s->method = new_method;
if (!ssl_init_wbio_buffer(s, 1))
goto err;
/* we are in this state */
s->state = SSL3_ST_SR_CLNT_HELLO_A;
if (type == 3) {
/*
* put the 'n' bytes we have read into the input buffer for SSLv3
*/
if (!RECORD_LAYER_set_data(&s->rlayer, buf, n))
goto err;
} else {
if (!RECORD_LAYER_set_data(&s->rlayer, NULL, 0))
goto err;
}
s->handshake_func = s->method->ssl_accept;
} else {
/* bad, very bad */
SSLerr(SSL_F_SSL23_GET_CLIENT_HELLO, SSL_R_UNKNOWN_PROTOCOL);
goto err;
}
s->init_num = 0;
if (buf != buf_space)
OPENSSL_free(buf);
return (SSL_accept(s));
err:
if (buf != buf_space)
OPENSSL_free(buf);
return (-1);
}
Reference in New Issue View Git Blame Copy Permalink