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boringssl/ssl/handshake_server.c
Steven Valdez 8f36c51f98 Revise version negotiation logic on the C side. 
This is in preparation for upcoming experiments which will require
supporting multiple experimental versions of TLS 1.3 with, on the
server, the ability to enable multiple variants at once. This means the
version <-> wire bijection no longer exists, even when limiting to a
single SSL*.  Thus version_to_wire is removed and instead we treat the
wire version as the canonical version value.

There is a mapping from valid wire versions to protocol versions which
describe the high-level handshake protocol in use. This mapping is not
injective, so uses of version_from_wire are rewritten differently.

All the version-munging logic is moved to ssl_versions.c with a master
preference list of all TLS and DTLS versions. The legacy version
negotiation is converted to the new scheme. The version lists and
negotiation are driven by the preference lists and a
ssl_supports_version API.

To simplify the mess around SSL_SESSION and versions, version_from_wire
is now DTLS/TLS-agnostic, with any filtering being done by
ssl_supports_version. This is screwy but allows parsing SSL_SESSIONs to
sanity-check it and reject all bogus versions in SSL_SESSION. This
reduces a mess of error cases.

As part of this, the weird logic where ssl->version is set early when
sending the ClientHello is removed. The one place where we were relying
on this behavior is tweaked to query hs->max_version instead.

Change-Id: Ic91b348481ceba94d9ae06d6781187c11adc15b0
Reviewed-on: https://boringssl-review.googlesource.com/17524
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
2017-07-05 19:13:17 +00:00

1728 lines
56 KiB
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/* 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) 1998-2007 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 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
*
* Portions of the attached software ("Contribution") are developed by
* SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
*
* The Contribution is licensed pursuant to the OpenSSL open source
* license provided above.
*
* ECC cipher suite support in OpenSSL originally written by
* Vipul Gupta and Sumit Gupta of Sun Microsystems Laboratories.
*
*/
/* ====================================================================
* Copyright 2005 Nokia. All rights reserved.
*
* The portions of the attached software ("Contribution") is developed by
* Nokia Corporation and is licensed pursuant to the OpenSSL open source
* license.
*
* The Contribution, originally written by Mika Kousa and Pasi Eronen of
* Nokia Corporation, consists of the "PSK" (Pre-Shared Key) ciphersuites
* support (see RFC 4279) to OpenSSL.
*
* No patent licenses or other rights except those expressly stated in
* the OpenSSL open source license shall be deemed granted or received
* expressly, by implication, estoppel, or otherwise.
*
* No assurances are provided by Nokia that the Contribution does not
* infringe the patent or other intellectual property rights of any third
* party or that the license provides you with all the necessary rights
* to make use of the Contribution.
*
* THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. IN
* ADDITION TO THE DISCLAIMERS INCLUDED IN THE LICENSE, NOKIA
* SPECIFICALLY DISCLAIMS ANY LIABILITY FOR CLAIMS BROUGHT BY YOU OR ANY
* OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
* OTHERWISE. */
#include <openssl/ssl.h>
#include <assert.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/buf.h>
#include <openssl/bytestring.h>
#include <openssl/cipher.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/md5.h>
#include <openssl/mem.h>
#include <openssl/nid.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#include "internal.h"
#include "../crypto/internal.h"
static int ssl3_process_client_hello(SSL_HANDSHAKE *hs);
static int ssl3_select_certificate(SSL_HANDSHAKE *hs);
static int ssl3_select_parameters(SSL_HANDSHAKE *hs);
static int ssl3_send_server_hello(SSL_HANDSHAKE *hs);
static int ssl3_send_server_certificate(SSL_HANDSHAKE *hs);
static int ssl3_send_server_key_exchange(SSL_HANDSHAKE *hs);
static int ssl3_send_server_hello_done(SSL_HANDSHAKE *hs);
static int ssl3_get_client_certificate(SSL_HANDSHAKE *hs);
static int ssl3_get_client_key_exchange(SSL_HANDSHAKE *hs);
static int ssl3_get_cert_verify(SSL_HANDSHAKE *hs);
static int ssl3_get_next_proto(SSL_HANDSHAKE *hs);
static int ssl3_get_channel_id(SSL_HANDSHAKE *hs);
static int ssl3_send_server_finished(SSL_HANDSHAKE *hs);
int ssl3_accept(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = -1;
assert(ssl->handshake_func == ssl3_accept);
assert(ssl->server);
for (;;) {
int state = hs->state;
switch (hs->state) {
case SSL_ST_INIT:
ssl_do_info_callback(ssl, SSL_CB_HANDSHAKE_START, 1);
hs->state = SSL3_ST_SR_CLNT_HELLO_A;
break;
case SSL3_ST_SR_CLNT_HELLO_A:
ret = ssl->method->ssl_get_message(ssl);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SR_CLNT_HELLO_B;
break;
case SSL3_ST_SR_CLNT_HELLO_B:
ret = ssl3_process_client_hello(hs);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SR_CLNT_HELLO_C;
break;
case SSL3_ST_SR_CLNT_HELLO_C:
ret = ssl3_select_certificate(hs);
if (ret <= 0) {
goto end;
}
if (hs->state != SSL_ST_TLS13) {
hs->state = SSL3_ST_SR_CLNT_HELLO_D;
}
break;
case SSL3_ST_SR_CLNT_HELLO_D:
ret = ssl3_select_parameters(hs);
if (ret <= 0) {
goto end;
}
ssl->method->received_flight(ssl);
hs->state = SSL3_ST_SW_SRVR_HELLO_A;
break;
case SSL3_ST_SW_SRVR_HELLO_A:
ret = ssl3_send_server_hello(hs);
if (ret <= 0) {
goto end;
}
if (ssl->session != NULL) {
hs->state = SSL3_ST_SW_FINISHED_A;
} else {
hs->state = SSL3_ST_SW_CERT_A;
}
break;
case SSL3_ST_SW_CERT_A:
ret = ssl3_send_server_certificate(hs);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SW_KEY_EXCH_A;
break;
case SSL3_ST_SW_KEY_EXCH_A:
if (hs->server_params_len > 0) {
ret = ssl3_send_server_key_exchange(hs);
if (ret <= 0) {
goto end;
}
}
hs->state = SSL3_ST_SW_SRVR_DONE_A;
break;
case SSL3_ST_SW_SRVR_DONE_A:
ret = ssl3_send_server_hello_done(hs);
if (ret <= 0) {
goto end;
}
hs->next_state = SSL3_ST_SR_CERT_A;
hs->state = SSL3_ST_SW_FLUSH;
break;
case SSL3_ST_SR_CERT_A:
if (hs->cert_request) {
ret = ssl3_get_client_certificate(hs);
if (ret <= 0) {
goto end;
}
}
hs->state = SSL3_ST_SR_KEY_EXCH_A;
break;
case SSL3_ST_SR_KEY_EXCH_A:
case SSL3_ST_SR_KEY_EXCH_B:
ret = ssl3_get_client_key_exchange(hs);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SR_CERT_VRFY_A;
break;
case SSL3_ST_SR_CERT_VRFY_A:
ret = ssl3_get_cert_verify(hs);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SR_CHANGE;
break;
case SSL3_ST_SR_CHANGE:
ret = ssl->method->read_change_cipher_spec(ssl);
if (ret <= 0) {
goto end;
}
if (!tls1_change_cipher_state(hs, SSL3_CHANGE_CIPHER_SERVER_READ)) {
ret = -1;
goto end;
}
hs->state = SSL3_ST_SR_NEXT_PROTO_A;
break;
case SSL3_ST_SR_NEXT_PROTO_A:
if (hs->next_proto_neg_seen) {
ret = ssl3_get_next_proto(hs);
if (ret <= 0) {
goto end;
}
}
hs->state = SSL3_ST_SR_CHANNEL_ID_A;
break;
case SSL3_ST_SR_CHANNEL_ID_A:
if (ssl->s3->tlsext_channel_id_valid) {
ret = ssl3_get_channel_id(hs);
if (ret <= 0) {
goto end;
}
}
hs->state = SSL3_ST_SR_FINISHED_A;
break;
case SSL3_ST_SR_FINISHED_A:
ret = ssl3_get_finished(hs);
if (ret <= 0) {
goto end;
}
ssl->method->received_flight(ssl);
if (ssl->session != NULL) {
hs->state = SSL_ST_OK;
} else {
hs->state = SSL3_ST_SW_FINISHED_A;
}
/* If this is a full handshake with ChannelID then record the handshake
* hashes in |hs->new_session| in case we need them to verify a
* ChannelID signature on a resumption of this session in the future. */
if (ssl->session == NULL && ssl->s3->tlsext_channel_id_valid) {
ret = tls1_record_handshake_hashes_for_channel_id(hs);
if (ret <= 0) {
goto end;
}
}
break;
case SSL3_ST_SW_FINISHED_A:
ret = ssl3_send_server_finished(hs);
if (ret <= 0) {
goto end;
}
hs->state = SSL3_ST_SW_FLUSH;
if (ssl->session != NULL) {
hs->next_state = SSL3_ST_SR_CHANGE;
} else {
hs->next_state = SSL_ST_OK;
}
break;
case SSL3_ST_SW_FLUSH:
ret = ssl->method->flush_flight(ssl);
if (ret <= 0) {
goto end;
}
hs->state = hs->next_state;
if (hs->state != SSL_ST_OK) {
ssl->method->expect_flight(ssl);
}
break;
case SSL_ST_TLS13: {
int early_return = 0;
ret = tls13_handshake(hs, &early_return);
if (ret <= 0) {
goto end;
}
if (early_return) {
ret = 1;
goto end;
}
hs->state = SSL_ST_OK;
break;
}
case SSL_ST_OK:
ssl->method->release_current_message(ssl, 1 /* free_buffer */);
/* If we aren't retaining peer certificates then we can discard it
* now. */
if (hs->new_session != NULL &&
ssl->retain_only_sha256_of_client_certs) {
sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
hs->new_session->certs = NULL;
ssl->ctx->x509_method->session_clear(hs->new_session);
}
SSL_SESSION_free(ssl->s3->established_session);
if (ssl->session != NULL) {
SSL_SESSION_up_ref(ssl->session);
ssl->s3->established_session = ssl->session;
} else {
ssl->s3->established_session = hs->new_session;
ssl->s3->established_session->not_resumable = 0;
hs->new_session = NULL;
}
ssl->s3->initial_handshake_complete = 1;
ssl_update_cache(hs, SSL_SESS_CACHE_SERVER);
ssl_do_info_callback(ssl, SSL_CB_HANDSHAKE_DONE, 1);
ret = 1;
goto end;
default:
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_STATE);
ret = -1;
goto end;
}
if (hs->state != state) {
ssl_do_info_callback(ssl, SSL_CB_ACCEPT_LOOP, 1);
}
}
end:
ssl_do_info_callback(ssl, SSL_CB_ACCEPT_EXIT, ret);
return ret;
}
int ssl_client_cipher_list_contains_cipher(const SSL_CLIENT_HELLO *client_hello,
uint16_t id) {
CBS cipher_suites;
CBS_init(&cipher_suites, client_hello->cipher_suites,
client_hello->cipher_suites_len);
while (CBS_len(&cipher_suites) > 0) {
uint16_t got_id;
if (!CBS_get_u16(&cipher_suites, &got_id)) {
return 0;
}
if (got_id == id) {
return 1;
}
}
return 0;
}
static int negotiate_version(SSL_HANDSHAKE *hs, uint8_t *out_alert,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
assert(!ssl->s3->have_version);
CBS supported_versions, versions;
if (ssl_client_hello_get_extension(client_hello, &supported_versions,
TLSEXT_TYPE_supported_versions)) {
if (!CBS_get_u8_length_prefixed(&supported_versions, &versions) ||
CBS_len(&supported_versions) != 0 ||
CBS_len(&versions) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return 0;
}
} else {
/* Convert the ClientHello version to an equivalent supported_versions
* extension. */
static const uint8_t kTLSVersions[] = {
0x03, 0x03, /* TLS 1.2 */
0x03, 0x02, /* TLS 1.1 */
0x03, 0x01, /* TLS 1 */
0x03, 0x00, /* SSL 3 */
};
static const uint8_t kDTLSVersions[] = {
0xfe, 0xfd, /* DTLS 1.2 */
0xfe, 0xff, /* DTLS 1.0 */
};
size_t versions_len = 0;
if (SSL_is_dtls(ssl)) {
if (client_hello->version <= DTLS1_2_VERSION) {
versions_len = 4;
} else if (client_hello->version <= DTLS1_VERSION) {
versions_len = 2;
}
CBS_init(&versions, kDTLSVersions + sizeof(kDTLSVersions) - versions_len,
versions_len);
} else {
if (client_hello->version >= TLS1_2_VERSION) {
versions_len = 8;
} else if (client_hello->version >= TLS1_1_VERSION) {
versions_len = 6;
} else if (client_hello->version >= TLS1_VERSION) {
versions_len = 4;
} else if (client_hello->version >= SSL3_VERSION) {
versions_len = 2;
}
CBS_init(&versions, kTLSVersions + sizeof(kTLSVersions) - versions_len,
versions_len);
}
}
if (!ssl_negotiate_version(hs, out_alert, &ssl->version, &versions)) {
return 0;
}
/* At this point, the connection's version is known and |ssl->version| is
* fixed. Begin enforcing the record-layer version. */
ssl->s3->have_version = 1;
/* Handle FALLBACK_SCSV. */
if (ssl_client_cipher_list_contains_cipher(client_hello,
SSL3_CK_FALLBACK_SCSV & 0xffff) &&
ssl3_protocol_version(ssl) < hs->max_version) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INAPPROPRIATE_FALLBACK);
*out_alert = SSL3_AD_INAPPROPRIATE_FALLBACK;
return 0;
}
return 1;
}
static STACK_OF(SSL_CIPHER) *
ssl_parse_client_cipher_list(const SSL_CLIENT_HELLO *client_hello) {
CBS cipher_suites;
CBS_init(&cipher_suites, client_hello->cipher_suites,
client_hello->cipher_suites_len);
STACK_OF(SSL_CIPHER) *sk = sk_SSL_CIPHER_new_null();
if (sk == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
while (CBS_len(&cipher_suites) > 0) {
uint16_t cipher_suite;
if (!CBS_get_u16(&cipher_suites, &cipher_suite)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST);
goto err;
}
const SSL_CIPHER *c = SSL_get_cipher_by_value(cipher_suite);
if (c != NULL && !sk_SSL_CIPHER_push(sk, c)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
}
return sk;
err:
sk_SSL_CIPHER_free(sk);
return NULL;
}
/* ssl_get_compatible_server_ciphers determines the key exchange and
* authentication cipher suite masks compatible with the server configuration
* and current ClientHello parameters of |hs|. It sets |*out_mask_k| to the key
* exchange mask and |*out_mask_a| to the authentication mask. */
static void ssl_get_compatible_server_ciphers(SSL_HANDSHAKE *hs,
uint32_t *out_mask_k,
uint32_t *out_mask_a) {
SSL *const ssl = hs->ssl;
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
*out_mask_k = SSL_kGENERIC;
*out_mask_a = SSL_aGENERIC;
return;
}
uint32_t mask_k = 0;
uint32_t mask_a = 0;
if (ssl_has_certificate(ssl)) {
mask_a |= ssl_cipher_auth_mask_for_key(hs->local_pubkey);
if (EVP_PKEY_id(hs->local_pubkey) == EVP_PKEY_RSA) {
mask_k |= SSL_kRSA;
}
}
/* Check for a shared group to consider ECDHE ciphers. */
uint16_t unused;
if (tls1_get_shared_group(hs, &unused)) {
mask_k |= SSL_kECDHE;
}
/* PSK requires a server callback. */
if (ssl->psk_server_callback != NULL) {
mask_k |= SSL_kPSK;
mask_a |= SSL_aPSK;
}
*out_mask_k = mask_k;
*out_mask_a = mask_a;
}
static const SSL_CIPHER *ssl3_choose_cipher(
SSL_HANDSHAKE *hs, const SSL_CLIENT_HELLO *client_hello,
const struct ssl_cipher_preference_list_st *server_pref) {
SSL *const ssl = hs->ssl;
STACK_OF(SSL_CIPHER) *prio, *allow;
/* in_group_flags will either be NULL, or will point to an array of bytes
* which indicate equal-preference groups in the |prio| stack. See the
* comment about |in_group_flags| in the |ssl_cipher_preference_list_st|
* struct. */
const uint8_t *in_group_flags;
/* group_min contains the minimal index so far found in a group, or -1 if no
* such value exists yet. */
int group_min = -1;
STACK_OF(SSL_CIPHER) *client_pref =
ssl_parse_client_cipher_list(client_hello);
if (client_pref == NULL) {
return NULL;
}
if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
prio = server_pref->ciphers;
in_group_flags = server_pref->in_group_flags;
allow = client_pref;
} else {
prio = client_pref;
in_group_flags = NULL;
allow = server_pref->ciphers;
}
uint32_t mask_k, mask_a;
ssl_get_compatible_server_ciphers(hs, &mask_k, &mask_a);
const SSL_CIPHER *ret = NULL;
for (size_t i = 0; i < sk_SSL_CIPHER_num(prio); i++) {
const SSL_CIPHER *c = sk_SSL_CIPHER_value(prio, i);
size_t cipher_index;
if (/* Check if the cipher is supported for the current version. */
SSL_CIPHER_get_min_version(c) <= ssl3_protocol_version(ssl) &&
ssl3_protocol_version(ssl) <= SSL_CIPHER_get_max_version(c) &&
/* Check the cipher is supported for the server configuration. */
(c->algorithm_mkey & mask_k) &&
(c->algorithm_auth & mask_a) &&
/* Check the cipher is in the |allow| list. */
sk_SSL_CIPHER_find(allow, &cipher_index, c)) {
if (in_group_flags != NULL && in_group_flags[i] == 1) {
/* This element of |prio| is in a group. Update the minimum index found
* so far and continue looking. */
if (group_min == -1 || (size_t)group_min > cipher_index) {
group_min = cipher_index;
}
} else {
if (group_min != -1 && (size_t)group_min < cipher_index) {
cipher_index = group_min;
}
ret = sk_SSL_CIPHER_value(allow, cipher_index);
break;
}
}
if (in_group_flags != NULL && in_group_flags[i] == 0 && group_min != -1) {
/* We are about to leave a group, but we found a match in it, so that's
* our answer. */
ret = sk_SSL_CIPHER_value(allow, group_min);
break;
}
}
sk_SSL_CIPHER_free(client_pref);
return ret;
}
static int ssl3_process_client_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) {
return -1;
}
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg,
ssl->init_num)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return -1;
}
/* Run the early callback. */
if (ssl->ctx->select_certificate_cb != NULL) {
switch (ssl->ctx->select_certificate_cb(&client_hello)) {
case ssl_select_cert_retry:
ssl->rwstate = SSL_CERTIFICATE_SELECTION_PENDING;
return -1;
case ssl_select_cert_error:
/* Connection rejected. */
OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return -1;
default:
/* fallthrough */;
}
}
/* Freeze the version range after the early callback. */
if (!ssl_get_version_range(ssl, &hs->min_version, &hs->max_version)) {
return -1;
}
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!negotiate_version(hs, &alert, &client_hello)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return -1;
}
hs->client_version = client_hello.version;
if (client_hello.random_len != SSL3_RANDOM_SIZE) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return -1;
}
OPENSSL_memcpy(ssl->s3->client_random, client_hello.random,
client_hello.random_len);
/* Only null compression is supported. TLS 1.3 further requires the peer
* advertise no other compression. */
if (OPENSSL_memchr(client_hello.compression_methods, 0,
client_hello.compression_methods_len) == NULL ||
(ssl3_protocol_version(ssl) >= TLS1_3_VERSION &&
client_hello.compression_methods_len != 1)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_COMPRESSION_LIST);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return -1;
}
/* TLS extensions. */
if (!ssl_parse_clienthello_tlsext(hs, &client_hello)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
return -1;
}
return 1;
}
static int ssl3_select_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
/* Call |cert_cb| to update server certificates if required. */
if (ssl->cert->cert_cb != NULL) {
int rv = ssl->cert->cert_cb(ssl, ssl->cert->cert_cb_arg);
if (rv == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return -1;
}
if (rv < 0) {
ssl->rwstate = SSL_X509_LOOKUP;
return -1;
}
}
if (!ssl_on_certificate_selected(hs)) {
return -1;
}
if (ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
/* Jump to the TLS 1.3 state machine. */
hs->state = SSL_ST_TLS13;
hs->do_tls13_handshake = tls13_server_handshake;
return 1;
}
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg,
ssl->init_num)) {
return -1;
}
/* Negotiate the cipher suite. This must be done after |cert_cb| so the
* certificate is finalized. */
hs->new_cipher =
ssl3_choose_cipher(hs, &client_hello, ssl_get_cipher_preferences(ssl));
if (hs->new_cipher == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return -1;
}
return 1;
}
static int ssl3_select_parameters(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = -1;
SSL_SESSION *session = NULL;
SSL_CLIENT_HELLO client_hello;
if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg,
ssl->init_num)) {
return -1;
}
/* Determine whether we are doing session resumption. */
int tickets_supported = 0, renew_ticket = 0;
switch (ssl_get_prev_session(ssl, &session, &tickets_supported, &renew_ticket,
&client_hello)) {
case ssl_session_success:
break;
case ssl_session_error:
goto err;
case ssl_session_retry:
ssl->rwstate = SSL_PENDING_SESSION;
goto err;
case ssl_session_ticket_retry:
ssl->rwstate = SSL_PENDING_TICKET;
goto err;
}
if (session != NULL) {
if (session->extended_master_secret && !hs->extended_master_secret) {
/* A ClientHello without EMS that attempts to resume a session with EMS
* is fatal to the connection. */
OPENSSL_PUT_ERROR(SSL, SSL_R_RESUMED_EMS_SESSION_WITHOUT_EMS_EXTENSION);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
goto err;
}
if (!ssl_session_is_resumable(hs, session) ||
/* If the client offers the EMS extension, but the previous session
* didn't use it, then negotiate a new session. */
hs->extended_master_secret != session->extended_master_secret) {
SSL_SESSION_free(session);
session = NULL;
}
}
if (session != NULL) {
/* Use the old session. */
hs->ticket_expected = renew_ticket;
ssl->session = session;
session = NULL;
ssl->s3->session_reused = 1;
} else {
hs->ticket_expected = tickets_supported;
ssl_set_session(ssl, NULL);
if (!ssl_get_new_session(hs, 1 /* server */)) {
goto err;
}
/* Clear the session ID if we want the session to be single-use. */
if (!(ssl->ctx->session_cache_mode & SSL_SESS_CACHE_SERVER)) {
hs->new_session->session_id_length = 0;
}
}
if (ssl->ctx->dos_protection_cb != NULL &&
ssl->ctx->dos_protection_cb(&client_hello) == 0) {
/* Connection rejected for DOS reasons. */
OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
if (ssl->session == NULL) {
hs->new_session->cipher = hs->new_cipher;
/* On new sessions, stash the SNI value in the session. */
if (hs->hostname != NULL) {
OPENSSL_free(hs->new_session->tlsext_hostname);
hs->new_session->tlsext_hostname = BUF_strdup(hs->hostname);
if (hs->new_session->tlsext_hostname == NULL) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
}
/* Determine whether to request a client certificate. */
hs->cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER);
/* Only request a certificate if Channel ID isn't negotiated. */
if ((ssl->verify_mode & SSL_VERIFY_PEER_IF_NO_OBC) &&
ssl->s3->tlsext_channel_id_valid) {
hs->cert_request = 0;
}
/* CertificateRequest may only be sent in certificate-based ciphers. */
if (!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->cert_request = 0;
}
if (!hs->cert_request) {
/* OpenSSL returns X509_V_OK when no certificates are requested. This is
* classed by them as a bug, but it's assumed by at least NGINX. */
hs->new_session->verify_result = X509_V_OK;
}
}
/* HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was
* deferred. Complete it now. */
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
goto err;
}
/* Now that all parameters are known, initialize the handshake hash and hash
* the ClientHello. */
if (!SSL_TRANSCRIPT_init_hash(&hs->transcript, ssl3_protocol_version(ssl),
hs->new_cipher->algorithm_prf) ||
!ssl_hash_current_message(hs)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
/* Release the handshake buffer if client authentication isn't required. */
if (!hs->cert_request) {
SSL_TRANSCRIPT_free_buffer(&hs->transcript);
}
ret = 1;
err:
SSL_SESSION_free(session);
return ret;
}
static int ssl3_send_server_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
/* We only accept ChannelIDs on connections with ECDHE in order to avoid a
* known attack while we fix ChannelID itself. */
if (ssl->s3->tlsext_channel_id_valid &&
(hs->new_cipher->algorithm_mkey & SSL_kECDHE) == 0) {
ssl->s3->tlsext_channel_id_valid = 0;
}
/* If this is a resumption and the original handshake didn't support
* ChannelID then we didn't record the original handshake hashes in the
* session and so cannot resume with ChannelIDs. */
if (ssl->session != NULL &&
ssl->session->original_handshake_hash_len == 0) {
ssl->s3->tlsext_channel_id_valid = 0;
}
struct OPENSSL_timeval now;
ssl_get_current_time(ssl, &now);
ssl->s3->server_random[0] = now.tv_sec >> 24;
ssl->s3->server_random[1] = now.tv_sec >> 16;
ssl->s3->server_random[2] = now.tv_sec >> 8;
ssl->s3->server_random[3] = now.tv_sec;
if (!RAND_bytes(ssl->s3->server_random + 4, SSL3_RANDOM_SIZE - 4)) {
return -1;
}
/* TODO(davidben): Implement the TLS 1.1 and 1.2 downgrade sentinels once TLS
* 1.3 is finalized and we are not implementing a draft version. */
const SSL_SESSION *session = hs->new_session;
if (ssl->session != NULL) {
session = ssl->session;
}
CBB cbb, body, session_id;
if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_SERVER_HELLO) ||
!CBB_add_u16(&body, ssl->version) ||
!CBB_add_bytes(&body, ssl->s3->server_random, SSL3_RANDOM_SIZE) ||
!CBB_add_u8_length_prefixed(&body, &session_id) ||
!CBB_add_bytes(&session_id, session->session_id,
session->session_id_length) ||
!CBB_add_u16(&body, ssl_cipher_get_value(hs->new_cipher)) ||
!CBB_add_u8(&body, 0 /* no compression */) ||
!ssl_add_serverhello_tlsext(hs, &body) ||
!ssl_add_message_cbb(ssl, &cbb)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
CBB_cleanup(&cbb);
return -1;
}
return 1;
}
static int ssl3_send_server_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = -1;
CBB cbb;
CBB_zero(&cbb);
if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
if (!ssl_has_certificate(ssl)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET);
goto err;
}
if (!ssl3_output_cert_chain(ssl)) {
goto err;
}
if (hs->certificate_status_expected) {
CBB body, ocsp_response;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_CERTIFICATE_STATUS) ||
!CBB_add_u8(&body, TLSEXT_STATUSTYPE_ocsp) ||
!CBB_add_u24_length_prefixed(&body, &ocsp_response) ||
!CBB_add_bytes(&ocsp_response,
CRYPTO_BUFFER_data(ssl->cert->ocsp_response),
CRYPTO_BUFFER_len(ssl->cert->ocsp_response)) ||
!ssl_add_message_cbb(ssl, &cbb)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
goto err;
}
}
}
/* Assemble ServerKeyExchange parameters if needed. */
uint32_t alg_k = hs->new_cipher->algorithm_mkey;
uint32_t alg_a = hs->new_cipher->algorithm_auth;
if (ssl_cipher_requires_server_key_exchange(hs->new_cipher) ||
((alg_a & SSL_aPSK) && ssl->psk_identity_hint)) {
/* Pre-allocate enough room to comfortably fit an ECDHE public key. Prepend
* the client and server randoms for the signing transcript. */
CBB child;
if (!CBB_init(&cbb, SSL3_RANDOM_SIZE * 2 + 128) ||
!CBB_add_bytes(&cbb, ssl->s3->client_random, SSL3_RANDOM_SIZE) ||
!CBB_add_bytes(&cbb, ssl->s3->server_random, SSL3_RANDOM_SIZE)) {
goto err;
}
/* PSK ciphers begin with an identity hint. */
if (alg_a & SSL_aPSK) {
size_t len =
(ssl->psk_identity_hint == NULL) ? 0 : strlen(ssl->psk_identity_hint);
if (!CBB_add_u16_length_prefixed(&cbb, &child) ||
!CBB_add_bytes(&child, (const uint8_t *)ssl->psk_identity_hint,
len)) {
goto err;
}
}
if (alg_k & SSL_kECDHE) {
/* Determine the group to use. */
uint16_t group_id;
if (!tls1_get_shared_group(hs, &group_id)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_TMP_ECDH_KEY);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
goto err;
}
hs->new_session->group_id = group_id;
/* Set up ECDH, generate a key, and emit the public half. */
if (!SSL_ECDH_CTX_init(&hs->ecdh_ctx, group_id) ||
!CBB_add_u8(&cbb, NAMED_CURVE_TYPE) ||
!CBB_add_u16(&cbb, group_id) ||
!CBB_add_u8_length_prefixed(&cbb, &child) ||
!SSL_ECDH_CTX_offer(&hs->ecdh_ctx, &child)) {
goto err;
}
} else {
assert(alg_k & SSL_kPSK);
}
if (!CBB_finish(&cbb, &hs->server_params, &hs->server_params_len)) {
goto err;
}
}
ret = 1;
err:
CBB_cleanup(&cbb);
return ret;
}
static int ssl3_send_server_key_exchange(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
CBB cbb, body, child;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_SERVER_KEY_EXCHANGE) ||
/* |hs->server_params| contains a prefix for signing. */
hs->server_params_len < 2 * SSL3_RANDOM_SIZE ||
!CBB_add_bytes(&body, hs->server_params + 2 * SSL3_RANDOM_SIZE,
hs->server_params_len - 2 * SSL3_RANDOM_SIZE)) {
goto err;
}
/* Add a signature. */
if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
if (!ssl_has_private_key(ssl)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
/* Determine the signature algorithm. */
uint16_t signature_algorithm;
if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
goto err;
}
if (ssl3_protocol_version(ssl) >= TLS1_2_VERSION) {
if (!CBB_add_u16(&body, signature_algorithm)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
}
/* Add space for the signature. */
const size_t max_sig_len = EVP_PKEY_size(hs->local_pubkey);
uint8_t *ptr;
if (!CBB_add_u16_length_prefixed(&body, &child) ||
!CBB_reserve(&child, &ptr, max_sig_len)) {
goto err;
}
size_t sig_len;
switch (ssl_private_key_sign(hs, ptr, &sig_len, max_sig_len,
signature_algorithm, hs->server_params,
hs->server_params_len)) {
case ssl_private_key_success:
if (!CBB_did_write(&child, sig_len)) {
goto err;
}
break;
case ssl_private_key_failure:
goto err;
case ssl_private_key_retry:
ssl->rwstate = SSL_PRIVATE_KEY_OPERATION;
goto err;
}
}
if (!ssl_add_message_cbb(ssl, &cbb)) {
goto err;
}
OPENSSL_free(hs->server_params);
hs->server_params = NULL;
hs->server_params_len = 0;
return 1;
err:
CBB_cleanup(&cbb);
return -1;
}
static int ssl3_send_server_hello_done(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
CBB cbb, body;
if (hs->cert_request) {
CBB cert_types, sigalgs_cbb;
if (!ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_CERTIFICATE_REQUEST) ||
!CBB_add_u8_length_prefixed(&body, &cert_types) ||
!CBB_add_u8(&cert_types, SSL3_CT_RSA_SIGN) ||
(ssl3_protocol_version(ssl) >= TLS1_VERSION &&
!CBB_add_u8(&cert_types, TLS_CT_ECDSA_SIGN)) ||
(ssl3_protocol_version(ssl) >= TLS1_2_VERSION &&
(!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb) ||
!tls12_add_verify_sigalgs(ssl, &sigalgs_cbb))) ||
!ssl_add_client_CA_list(ssl, &body) ||
!ssl_add_message_cbb(ssl, &cbb)) {
goto err;
}
}
if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_SERVER_HELLO_DONE) ||
!ssl_add_message_cbb(ssl, &cbb)) {
goto err;
}
return 1;
err:
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
CBB_cleanup(&cbb);
return -1;
}
static int ssl3_get_client_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
assert(hs->cert_request);
int msg_ret = ssl->method->ssl_get_message(ssl);
if (msg_ret <= 0) {
return msg_ret;
}
if (ssl->s3->tmp.message_type != SSL3_MT_CERTIFICATE) {
if (ssl->version == SSL3_VERSION &&
ssl->s3->tmp.message_type == SSL3_MT_CLIENT_KEY_EXCHANGE) {
/* In SSL 3.0, the Certificate message is omitted to signal no
* certificate. */
if (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return -1;
}
/* OpenSSL returns X509_V_OK when no certificates are received. This is
* classed by them as a bug, but it's assumed by at least NGINX. */
hs->new_session->verify_result = X509_V_OK;
ssl->s3->tmp.reuse_message = 1;
return 1;
}
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
return -1;
}
if (!ssl_hash_current_message(hs)) {
return -1;
}
CBS certificate_msg;
CBS_init(&certificate_msg, ssl->init_msg, ssl->init_num);
sk_CRYPTO_BUFFER_pop_free(hs->new_session->certs, CRYPTO_BUFFER_free);
EVP_PKEY_free(hs->peer_pubkey);
hs->peer_pubkey = NULL;
uint8_t alert = SSL_AD_DECODE_ERROR;
hs->new_session->certs = ssl_parse_cert_chain(
&alert, &hs->peer_pubkey,
ssl->retain_only_sha256_of_client_certs ? hs->new_session->peer_sha256
: NULL,
&certificate_msg, ssl->ctx->pool);
if (hs->new_session->certs == NULL) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return -1;
}
if (CBS_len(&certificate_msg) != 0 ||
!ssl->ctx->x509_method->session_cache_objects(hs->new_session)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return -1;
}
if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) {
/* No client certificate so the handshake buffer may be discarded. */
SSL_TRANSCRIPT_free_buffer(&hs->transcript);
/* In SSL 3.0, sending no certificate is signaled by omitting the
* Certificate message. */
if (ssl->version == SSL3_VERSION) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATES_RETURNED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return -1;
}
if (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) {
/* Fail for TLS only if we required a certificate */
OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return -1;
}
/* OpenSSL returns X509_V_OK when no certificates are received. This is
* classed by them as a bug, but it's assumed by at least NGINX. */
hs->new_session->verify_result = X509_V_OK;
return 1;
}
/* The hash will have been filled in. */
if (ssl->retain_only_sha256_of_client_certs) {
hs->new_session->peer_sha256_valid = 1;
}
if (!ssl->ctx->x509_method->session_verify_cert_chain(hs->new_session, ssl)) {
return -1;
}
return 1;
}
static int ssl3_get_client_key_exchange(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
CBS client_key_exchange;
uint8_t *premaster_secret = NULL;
size_t premaster_secret_len = 0;
uint8_t *decrypt_buf = NULL;
if (hs->state == SSL3_ST_SR_KEY_EXCH_A) {
int ret = ssl->method->ssl_get_message(ssl);
if (ret <= 0) {
return ret;
}
}
if (!ssl_check_message_type(ssl, SSL3_MT_CLIENT_KEY_EXCHANGE)) {
return -1;
}
CBS_init(&client_key_exchange, ssl->init_msg, ssl->init_num);
uint32_t alg_k = hs->new_cipher->algorithm_mkey;
uint32_t alg_a = hs->new_cipher->algorithm_auth;
/* If using a PSK key exchange, parse the PSK identity. */
if (alg_a & SSL_aPSK) {
CBS psk_identity;
/* If using PSK, the ClientKeyExchange contains a psk_identity. If PSK,
* then this is the only field in the message. */
if (!CBS_get_u16_length_prefixed(&client_key_exchange, &psk_identity) ||
((alg_k & SSL_kPSK) && CBS_len(&client_key_exchange) != 0)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
goto err;
}
if (CBS_len(&psk_identity) > PSK_MAX_IDENTITY_LEN ||
CBS_contains_zero_byte(&psk_identity)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
goto err;
}
if (!CBS_strdup(&psk_identity, &hs->new_session->psk_identity)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
}
/* Depending on the key exchange method, compute |premaster_secret| and
* |premaster_secret_len|. */
if (alg_k & SSL_kRSA) {
CBS encrypted_premaster_secret;
if (ssl->version > SSL3_VERSION) {
if (!CBS_get_u16_length_prefixed(&client_key_exchange,
&encrypted_premaster_secret) ||
CBS_len(&client_key_exchange) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
goto err;
}
} else {
encrypted_premaster_secret = client_key_exchange;
}
/* Allocate a buffer large enough for an RSA decryption. */
const size_t rsa_size = EVP_PKEY_size(hs->local_pubkey);
decrypt_buf = OPENSSL_malloc(rsa_size);
if (decrypt_buf == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
/* Decrypt with no padding. PKCS#1 padding will be removed as part of the
* timing-sensitive code below. */
size_t decrypt_len;
switch (ssl_private_key_decrypt(hs, decrypt_buf, &decrypt_len, rsa_size,
CBS_data(&encrypted_premaster_secret),
CBS_len(&encrypted_premaster_secret))) {
case ssl_private_key_success:
break;
case ssl_private_key_failure:
goto err;
case ssl_private_key_retry:
ssl->rwstate = SSL_PRIVATE_KEY_OPERATION;
hs->state = SSL3_ST_SR_KEY_EXCH_B;
goto err;
}
if (decrypt_len != rsa_size) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
goto err;
}
/* Prepare a random premaster, to be used on invalid padding. See RFC 5246,
* section 7.4.7.1. */
premaster_secret_len = SSL_MAX_MASTER_KEY_LENGTH;
premaster_secret = OPENSSL_malloc(premaster_secret_len);
if (premaster_secret == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!RAND_bytes(premaster_secret, premaster_secret_len)) {
goto err;
}
/* The smallest padded premaster is 11 bytes of overhead. Small keys are
* publicly invalid. */
if (decrypt_len < 11 + premaster_secret_len) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
goto err;
}
/* Check the padding. See RFC 3447, section 7.2.2. */
size_t padding_len = decrypt_len - premaster_secret_len;
uint8_t good = constant_time_eq_int_8(decrypt_buf[0], 0) &
constant_time_eq_int_8(decrypt_buf[1], 2);
for (size_t i = 2; i < padding_len - 1; i++) {
good &= ~constant_time_is_zero_8(decrypt_buf[i]);
}
good &= constant_time_is_zero_8(decrypt_buf[padding_len - 1]);
/* The premaster secret must begin with |client_version|. This too must be
* checked in constant time (http://eprint.iacr.org/2003/052/). */
good &= constant_time_eq_8(decrypt_buf[padding_len],
(unsigned)(hs->client_version >> 8));
good &= constant_time_eq_8(decrypt_buf[padding_len + 1],
(unsigned)(hs->client_version & 0xff));
/* Select, in constant time, either the decrypted premaster or the random
* premaster based on |good|. */
for (size_t i = 0; i < premaster_secret_len; i++) {
premaster_secret[i] = constant_time_select_8(
good, decrypt_buf[padding_len + i], premaster_secret[i]);
}
OPENSSL_free(decrypt_buf);
decrypt_buf = NULL;
} else if (alg_k & SSL_kECDHE) {
/* Parse the ClientKeyExchange. */
CBS peer_key;
if (!CBS_get_u8_length_prefixed(&client_key_exchange, &peer_key) ||
CBS_len(&client_key_exchange) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
goto err;
}
/* Compute the premaster. */
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!SSL_ECDH_CTX_finish(&hs->ecdh_ctx, &premaster_secret,
&premaster_secret_len, &alert, CBS_data(&peer_key),
CBS_len(&peer_key))) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
goto err;
}
/* The key exchange state may now be discarded. */
SSL_ECDH_CTX_cleanup(&hs->ecdh_ctx);
} else if (!(alg_k & SSL_kPSK)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CIPHER_TYPE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
goto err;
}
/* For a PSK cipher suite, the actual pre-master secret is combined with the
* pre-shared key. */
if (alg_a & SSL_aPSK) {
if (ssl->psk_server_callback == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_NO_SERVER_CB);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
}
/* Look up the key for the identity. */
uint8_t psk[PSK_MAX_PSK_LEN];
unsigned psk_len = ssl->psk_server_callback(
ssl, hs->new_session->psk_identity, psk, sizeof(psk));
if (psk_len > PSK_MAX_PSK_LEN) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
goto err;
} else if (psk_len == 0) {
/* PSK related to the given identity not found */
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNKNOWN_PSK_IDENTITY);
goto err;
}
if (alg_k & SSL_kPSK) {
/* In plain PSK, other_secret is a block of 0s with the same length as the
* pre-shared key. */
premaster_secret_len = psk_len;
premaster_secret = OPENSSL_malloc(premaster_secret_len);
if (premaster_secret == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
goto err;
}
OPENSSL_memset(premaster_secret, 0, premaster_secret_len);
}
CBB new_premaster, child;
uint8_t *new_data;
size_t new_len;
CBB_zero(&new_premaster);
if (!CBB_init(&new_premaster, 2 + psk_len + 2 + premaster_secret_len) ||
!CBB_add_u16_length_prefixed(&new_premaster, &child) ||
!CBB_add_bytes(&child, premaster_secret, premaster_secret_len) ||
!CBB_add_u16_length_prefixed(&new_premaster, &child) ||
!CBB_add_bytes(&child, psk, psk_len) ||
!CBB_finish(&new_premaster, &new_data, &new_len)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
CBB_cleanup(&new_premaster);
goto err;
}
OPENSSL_cleanse(premaster_secret, premaster_secret_len);
OPENSSL_free(premaster_secret);
premaster_secret = new_data;
premaster_secret_len = new_len;
}
if (!ssl_hash_current_message(hs)) {
goto err;
}
/* Compute the master secret */
hs->new_session->master_key_length = tls1_generate_master_secret(
hs, hs->new_session->master_key, premaster_secret, premaster_secret_len);
if (hs->new_session->master_key_length == 0) {
goto err;
}
hs->new_session->extended_master_secret = hs->extended_master_secret;
OPENSSL_cleanse(premaster_secret, premaster_secret_len);
OPENSSL_free(premaster_secret);
return 1;
err:
if (premaster_secret != NULL) {
OPENSSL_cleanse(premaster_secret, premaster_secret_len);
OPENSSL_free(premaster_secret);
}
OPENSSL_free(decrypt_buf);
return -1;
}
static int ssl3_get_cert_verify(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
CBS certificate_verify, signature;
/* Only RSA and ECDSA client certificates are supported, so a
* CertificateVerify is required if and only if there's a client certificate.
* */
if (hs->peer_pubkey == NULL) {
SSL_TRANSCRIPT_free_buffer(&hs->transcript);
return 1;
}
int msg_ret = ssl->method->ssl_get_message(ssl);
if (msg_ret <= 0) {
return msg_ret;
}
if (!ssl_check_message_type(ssl, SSL3_MT_CERTIFICATE_VERIFY)) {
return -1;
}
CBS_init(&certificate_verify, ssl->init_msg, ssl->init_num);
/* Determine the digest type if needbe. */
uint16_t signature_algorithm = 0;
if (ssl3_protocol_version(ssl) >= TLS1_2_VERSION) {
if (!CBS_get_u16(&certificate_verify, &signature_algorithm)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return -1;
}
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!tls12_check_peer_sigalg(ssl, &alert, signature_algorithm)) {
ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
return -1;
}
hs->new_session->peer_signature_algorithm = signature_algorithm;
} else if (!tls1_get_legacy_signature_algorithm(&signature_algorithm,
hs->peer_pubkey)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_ERROR_UNSUPPORTED_CERTIFICATE_TYPE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_CERTIFICATE);
return -1;
}
/* Parse and verify the signature. */
if (!CBS_get_u16_length_prefixed(&certificate_verify, &signature) ||
CBS_len(&certificate_verify) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return -1;
}
int sig_ok;
/* The SSL3 construction for CertificateVerify does not decompose into a
* single final digest and signature, and must be special-cased. */
if (ssl3_protocol_version(ssl) == SSL3_VERSION) {
uint8_t digest[EVP_MAX_MD_SIZE];
size_t digest_len;
if (!SSL_TRANSCRIPT_ssl3_cert_verify_hash(&hs->transcript, digest,
&digest_len, hs->new_session,
signature_algorithm)) {
return -1;
}
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new(hs->peer_pubkey, NULL);
sig_ok = pctx != NULL &&
EVP_PKEY_verify_init(pctx) &&
EVP_PKEY_verify(pctx, CBS_data(&signature), CBS_len(&signature),
digest, digest_len);
EVP_PKEY_CTX_free(pctx);
} else {
sig_ok = ssl_public_key_verify(
ssl, CBS_data(&signature), CBS_len(&signature), signature_algorithm,
hs->peer_pubkey, (const uint8_t *)hs->transcript.buffer->data,
hs->transcript.buffer->length);
}
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
sig_ok = 1;
ERR_clear_error();
#endif
if (!sig_ok) {
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
return -1;
}
/* The handshake buffer is no longer necessary, and we may hash the current
* message.*/
SSL_TRANSCRIPT_free_buffer(&hs->transcript);
if (!ssl_hash_current_message(hs)) {
return -1;
}
return 1;
}
/* ssl3_get_next_proto reads a Next Protocol Negotiation handshake message. It
* sets the next_proto member in s if found */
static int ssl3_get_next_proto(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int ret = ssl->method->ssl_get_message(ssl);
if (ret <= 0) {
return ret;
}
if (!ssl_check_message_type(ssl, SSL3_MT_NEXT_PROTO) ||
!ssl_hash_current_message(hs)) {
return -1;
}
CBS next_protocol, selected_protocol, padding;
CBS_init(&next_protocol, ssl->init_msg, ssl->init_num);
if (!CBS_get_u8_length_prefixed(&next_protocol, &selected_protocol) ||
!CBS_get_u8_length_prefixed(&next_protocol, &padding) ||
CBS_len(&next_protocol) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return 0;
}
if (!CBS_stow(&selected_protocol, &ssl->s3->next_proto_negotiated,
&ssl->s3->next_proto_negotiated_len)) {
return 0;
}
return 1;
}
/* ssl3_get_channel_id reads and verifies a ClientID handshake message. */
static int ssl3_get_channel_id(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
int msg_ret = ssl->method->ssl_get_message(ssl);
if (msg_ret <= 0) {
return msg_ret;
}
if (!ssl_check_message_type(ssl, SSL3_MT_CHANNEL_ID) ||
!tls1_verify_channel_id(hs) ||
!ssl_hash_current_message(hs)) {
return -1;
}
return 1;
}
static int ssl3_send_server_finished(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (hs->ticket_expected) {
const SSL_SESSION *session;
SSL_SESSION *session_copy = NULL;
if (ssl->session == NULL) {
/* Fix the timeout to measure from the ticket issuance time. */
ssl_session_rebase_time(ssl, hs->new_session);
session = hs->new_session;
} else {
/* We are renewing an existing session. Duplicate the session to adjust
* the timeout. */
session_copy = SSL_SESSION_dup(ssl->session, SSL_SESSION_INCLUDE_NONAUTH);
if (session_copy == NULL) {
return -1;
}
ssl_session_rebase_time(ssl, session_copy);
session = session_copy;
}
CBB cbb, body, ticket;
int ok = ssl->method->init_message(ssl, &cbb, &body,
SSL3_MT_NEW_SESSION_TICKET) &&
CBB_add_u32(&body, session->timeout) &&
CBB_add_u16_length_prefixed(&body, &ticket) &&
ssl_encrypt_ticket(ssl, &ticket, session) &&
ssl_add_message_cbb(ssl, &cbb);
SSL_SESSION_free(session_copy);
CBB_cleanup(&cbb);
if (!ok) {
return -1;
}
}
if (!ssl->method->add_change_cipher_spec(ssl) ||
!tls1_change_cipher_state(hs, SSL3_CHANGE_CIPHER_SERVER_WRITE)) {
return -1;
}
return ssl3_send_finished(hs);
}
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