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f1af129fb4
boringssl/ssl/handshake_client.cc
Steven Valdez f1af129fb4 Implement TLS 1.3 anti-downgrade signal. 
Change-Id: Ib4739350948ec339457d993daef582748ed8f100
Reviewed-on: https://boringssl-review.googlesource.com/30924
Commit-Queue: Steven Valdez <svaldez@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Reviewed-by: David Benjamin <davidben@google.com>
2018-08-15 15:23:43 +00:00

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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 <limits.h>
#include <string.h>
#include <utility>
#include <openssl/aead.h>
#include <openssl/bn.h>
#include <openssl/buf.h>
#include <openssl/bytestring.h>
#include <openssl/ec_key.h>
#include <openssl/ecdsa.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/md5.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include "../crypto/internal.h"
#include "internal.h"
namespace bssl {
enum ssl_client_hs_state_t {
state_start_connect = 0,
state_enter_early_data,
state_read_hello_verify_request,
state_read_server_hello,
state_tls13,
state_read_server_certificate,
state_read_certificate_status,
state_verify_server_certificate,
state_reverify_server_certificate,
state_read_server_key_exchange,
state_read_certificate_request,
state_read_server_hello_done,
state_send_client_certificate,
state_send_client_key_exchange,
state_send_client_certificate_verify,
state_send_client_finished,
state_finish_flight,
state_read_session_ticket,
state_process_change_cipher_spec,
state_read_server_finished,
state_finish_client_handshake,
state_done,
};
// ssl_get_client_disabled sets |*out_mask_a| and |*out_mask_k| to masks of
// disabled algorithms.
static void ssl_get_client_disabled(SSL_HANDSHAKE *hs, uint32_t *out_mask_a,
uint32_t *out_mask_k) {
*out_mask_a = 0;
*out_mask_k = 0;
// PSK requires a client callback.
if (hs->config->psk_client_callback == NULL) {
*out_mask_a |= SSL_aPSK;
*out_mask_k |= SSL_kPSK;
}
}
static int ssl_write_client_cipher_list(SSL_HANDSHAKE *hs, CBB *out) {
SSL *const ssl = hs->ssl;
uint32_t mask_a, mask_k;
ssl_get_client_disabled(hs, &mask_a, &mask_k);
CBB child;
if (!CBB_add_u16_length_prefixed(out, &child)) {
return 0;
}
// Add a fake cipher suite. See draft-davidben-tls-grease-01.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&child, ssl_get_grease_value(hs, ssl_grease_cipher))) {
return 0;
}
// Add TLS 1.3 ciphers. Order ChaCha20-Poly1305 relative to AES-GCM based on
// hardware support.
if (hs->max_version >= TLS1_3_VERSION) {
if (!EVP_has_aes_hardware() &&
!CBB_add_u16(&child, TLS1_CK_CHACHA20_POLY1305_SHA256 & 0xffff)) {
return 0;
}
if (!CBB_add_u16(&child, TLS1_CK_AES_128_GCM_SHA256 & 0xffff) ||
!CBB_add_u16(&child, TLS1_CK_AES_256_GCM_SHA384 & 0xffff)) {
return 0;
}
if (EVP_has_aes_hardware() &&
!CBB_add_u16(&child, TLS1_CK_CHACHA20_POLY1305_SHA256 & 0xffff)) {
return 0;
}
}
if (hs->min_version < TLS1_3_VERSION) {
int any_enabled = 0;
for (const SSL_CIPHER *cipher : SSL_get_ciphers(ssl)) {
// Skip disabled ciphers
if ((cipher->algorithm_mkey & mask_k) ||
(cipher->algorithm_auth & mask_a)) {
continue;
}
if (SSL_CIPHER_get_min_version(cipher) > hs->max_version ||
SSL_CIPHER_get_max_version(cipher) < hs->min_version) {
continue;
}
any_enabled = 1;
if (!CBB_add_u16(&child, ssl_cipher_get_value(cipher))) {
return 0;
}
}
// If all ciphers were disabled, return the error to the caller.
if (!any_enabled && hs->max_version < TLS1_3_VERSION) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CIPHERS_AVAILABLE);
return 0;
}
}
if (ssl->mode & SSL_MODE_SEND_FALLBACK_SCSV) {
if (!CBB_add_u16(&child, SSL3_CK_FALLBACK_SCSV & 0xffff)) {
return 0;
}
}
return CBB_flush(out);
}
int ssl_write_client_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ScopedCBB cbb;
CBB body;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CLIENT_HELLO)) {
return 0;
}
CBB child;
if (!CBB_add_u16(&body, hs->client_version) ||
!CBB_add_bytes(&body, ssl->s3->client_random, SSL3_RANDOM_SIZE) ||
!CBB_add_u8_length_prefixed(&body, &child)) {
return 0;
}
// Do not send a session ID on renegotiation.
if (!ssl->s3->initial_handshake_complete &&
!CBB_add_bytes(&child, hs->session_id, hs->session_id_len)) {
return 0;
}
if (SSL_is_dtls(ssl)) {
if (!CBB_add_u8_length_prefixed(&body, &child) ||
!CBB_add_bytes(&child, ssl->d1->cookie, ssl->d1->cookie_len)) {
return 0;
}
}
size_t header_len =
SSL_is_dtls(ssl) ? DTLS1_HM_HEADER_LENGTH : SSL3_HM_HEADER_LENGTH;
if (!ssl_write_client_cipher_list(hs, &body) ||
!CBB_add_u8(&body, 1 /* one compression method */) ||
!CBB_add_u8(&body, 0 /* null compression */) ||
!ssl_add_clienthello_tlsext(hs, &body, header_len + CBB_len(&body))) {
return 0;
}
Array<uint8_t> msg;
if (!ssl->method->finish_message(ssl, cbb.get(), &msg)) {
return 0;
}
// Now that the length prefixes have been computed, fill in the placeholder
// PSK binder.
if (hs->needs_psk_binder &&
!tls13_write_psk_binder(hs, msg.data(), msg.size())) {
return 0;
}
return ssl->method->add_message(ssl, std::move(msg));
}
static bool parse_supported_versions(SSL_HANDSHAKE *hs, uint16_t *version,
const CBS *in) {
// If the outer version is not TLS 1.2, or there is no extensions block, use
// the outer version.
if (*version != TLS1_2_VERSION || CBS_len(in) == 0) {
return true;
}
SSL *const ssl = hs->ssl;
CBS copy = *in, extensions;
if (!CBS_get_u16_length_prefixed(&copy, &extensions) ||
CBS_len(&copy) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return false;
}
bool have_supported_versions;
CBS supported_versions;
const SSL_EXTENSION_TYPE ext_types[] = {
{TLSEXT_TYPE_supported_versions, &have_supported_versions,
&supported_versions},
};
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_parse_extensions(&extensions, &alert, ext_types,
OPENSSL_ARRAY_SIZE(ext_types),
1 /* ignore unknown */)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return false;
}
// Override the outer version with the extension, if present.
if (have_supported_versions &&
(!CBS_get_u16(&supported_versions, version) ||
CBS_len(&supported_versions) != 0)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return false;
}
return true;
}
static enum ssl_hs_wait_t do_start_connect(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ssl_do_info_callback(ssl, SSL_CB_HANDSHAKE_START, 1);
// |session_reused| must be reset in case this is a renegotiation.
ssl->s3->session_reused = false;
// Freeze the version range.
if (!ssl_get_version_range(hs, &hs->min_version, &hs->max_version)) {
return ssl_hs_error;
}
// Always advertise the ClientHello version from the original maximum version,
// even on renegotiation. The static RSA key exchange uses this field, and
// some servers fail when it changes across handshakes.
if (SSL_is_dtls(hs->ssl)) {
hs->client_version =
hs->max_version >= TLS1_2_VERSION ? DTLS1_2_VERSION : DTLS1_VERSION;
} else {
hs->client_version =
hs->max_version >= TLS1_2_VERSION ? TLS1_2_VERSION : hs->max_version;
}
// If the configured session has expired or was created at a disabled
// version, drop it.
if (ssl->session != NULL) {
if (ssl->session->is_server ||
!ssl_supports_version(hs, ssl->session->ssl_version) ||
(ssl->session->session_id_length == 0 &&
ssl->session->ticket.empty()) ||
ssl->session->not_resumable ||
!ssl_session_is_time_valid(ssl, ssl->session.get())) {
ssl_set_session(ssl, NULL);
}
}
if (!RAND_bytes(ssl->s3->client_random, sizeof(ssl->s3->client_random))) {
return ssl_hs_error;
}
// Initialize a random session ID for the experimental TLS 1.3 variant
// requiring a session id.
if (ssl->session != nullptr &&
!ssl->s3->initial_handshake_complete &&
ssl->session->session_id_length > 0) {
hs->session_id_len = ssl->session->session_id_length;
OPENSSL_memcpy(hs->session_id, ssl->session->session_id,
hs->session_id_len);
} else if (hs->max_version >= TLS1_3_VERSION) {
hs->session_id_len = sizeof(hs->session_id);
if (!RAND_bytes(hs->session_id, hs->session_id_len)) {
return ssl_hs_error;
}
}
if (!ssl_write_client_hello(hs)) {
return ssl_hs_error;
}
hs->state = state_enter_early_data;
return ssl_hs_flush;
}
static enum ssl_hs_wait_t do_enter_early_data(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (SSL_is_dtls(ssl)) {
hs->state = state_read_hello_verify_request;
return ssl_hs_ok;
}
if (!hs->early_data_offered) {
hs->state = state_read_server_hello;
return ssl_hs_ok;
}
ssl->s3->aead_write_ctx->SetVersionIfNullCipher(ssl->session->ssl_version);
if (!ssl->method->add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
if (!tls13_init_early_key_schedule(hs, ssl->session->master_key,
ssl->session->master_key_length) ||
!tls13_derive_early_secrets(hs) ||
!tls13_set_traffic_key(ssl, evp_aead_seal, hs->early_traffic_secret,
hs->hash_len)) {
return ssl_hs_error;
}
// Stash the early data session, so connection properties may be queried out
// of it.
hs->in_early_data = true;
hs->early_session = UpRef(ssl->session);
hs->can_early_write = true;
hs->state = state_read_server_hello;
return ssl_hs_early_return;
}
static enum ssl_hs_wait_t do_read_hello_verify_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
assert(SSL_is_dtls(ssl));
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (msg.type != DTLS1_MT_HELLO_VERIFY_REQUEST) {
hs->state = state_read_server_hello;
return ssl_hs_ok;
}
CBS hello_verify_request = msg.body, cookie;
uint16_t server_version;
if (!CBS_get_u16(&hello_verify_request, &server_version) ||
!CBS_get_u8_length_prefixed(&hello_verify_request, &cookie) ||
CBS_len(&cookie) > sizeof(ssl->d1->cookie) ||
CBS_len(&hello_verify_request) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
OPENSSL_memcpy(ssl->d1->cookie, CBS_data(&cookie), CBS_len(&cookie));
ssl->d1->cookie_len = CBS_len(&cookie);
ssl->method->next_message(ssl);
// DTLS resets the handshake buffer after HelloVerifyRequest.
if (!hs->transcript.Init()) {
return ssl_hs_error;
}
if (!ssl_write_client_hello(hs)) {
return ssl_hs_error;
}
hs->state = state_read_server_hello;
return ssl_hs_flush;
}
static enum ssl_hs_wait_t do_read_server_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_server_hello;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_SERVER_HELLO)) {
return ssl_hs_error;
}
CBS server_hello = msg.body, server_random, session_id;
uint16_t server_version, cipher_suite;
uint8_t compression_method;
if (!CBS_get_u16(&server_hello, &server_version) ||
!CBS_get_bytes(&server_hello, &server_random, SSL3_RANDOM_SIZE) ||
!CBS_get_u8_length_prefixed(&server_hello, &session_id) ||
CBS_len(&session_id) > SSL3_SESSION_ID_SIZE ||
!CBS_get_u16(&server_hello, &cipher_suite) ||
!CBS_get_u8(&server_hello, &compression_method)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
// Use the supported_versions extension if applicable.
if (!parse_supported_versions(hs, &server_version, &server_hello)) {
return ssl_hs_error;
}
if (!ssl_supports_version(hs, server_version)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_PROTOCOL);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_PROTOCOL_VERSION);
return ssl_hs_error;
}
assert(ssl->s3->have_version == ssl->s3->initial_handshake_complete);
if (!ssl->s3->have_version) {
ssl->version = server_version;
// At this point, the connection's version is known and ssl->version is
// fixed. Begin enforcing the record-layer version.
ssl->s3->have_version = true;
ssl->s3->aead_write_ctx->SetVersionIfNullCipher(ssl->version);
} else if (server_version != ssl->version) {
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SSL_VERSION);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_PROTOCOL_VERSION);
return ssl_hs_error;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
hs->state = state_tls13;
return ssl_hs_ok;
}
// Clear some TLS 1.3 state that no longer needs to be retained.
hs->key_share.reset();
hs->key_share_bytes.Reset();
// A TLS 1.2 server would not know to skip the early data we offered. Report
// an error code sooner. The caller may use this error code to implement the
// fallback described in draft-ietf-tls-tls13-18 appendix C.3.
if (hs->early_data_offered) {
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_VERSION_ON_EARLY_DATA);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_PROTOCOL_VERSION);
return ssl_hs_error;
}
// Copy over the server random.
OPENSSL_memcpy(ssl->s3->server_random, CBS_data(&server_random),
SSL3_RANDOM_SIZE);
// Enforce the TLS 1.3 anti-downgrade feature.
if (!ssl->s3->initial_handshake_complete &&
ssl_supports_version(hs, TLS1_3_VERSION)) {
static_assert(
sizeof(kTLS12DowngradeRandom) == sizeof(kTLS13DowngradeRandom),
"downgrade signals have different size");
auto suffix =
MakeConstSpan(ssl->s3->server_random, sizeof(ssl->s3->server_random))
.subspan(SSL3_RANDOM_SIZE - sizeof(kTLS13DowngradeRandom));
if (suffix == kTLS12DowngradeRandom || suffix == kTLS13DowngradeRandom) {
ssl->s3->tls13_downgrade = true;
if (!ssl->ctx->ignore_tls13_downgrade) {
OPENSSL_PUT_ERROR(SSL, SSL_R_TLS13_DOWNGRADE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
}
}
if (!ssl->s3->initial_handshake_complete && ssl->session != NULL &&
ssl->session->session_id_length != 0 &&
CBS_mem_equal(&session_id, ssl->session->session_id,
ssl->session->session_id_length)) {
ssl->s3->session_reused = true;
} else {
// The server may also have echoed back the TLS 1.3 compatibility mode
// session ID. As we know this is not a session the server knows about, any
// server resuming it is in error. Reject the first connection
// deterministicly, rather than installing an invalid session into the
// session cache. https://crbug.com/796910
if (hs->session_id_len != 0 &&
CBS_mem_equal(&session_id, hs->session_id, hs->session_id_len)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_SERVER_ECHOED_INVALID_SESSION_ID);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// The session wasn't resumed. Create a fresh SSL_SESSION to
// fill out.
ssl_set_session(ssl, NULL);
if (!ssl_get_new_session(hs, 0 /* client */)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
// Note: session_id could be empty.
hs->new_session->session_id_length = CBS_len(&session_id);
OPENSSL_memcpy(hs->new_session->session_id, CBS_data(&session_id),
CBS_len(&session_id));
}
const SSL_CIPHER *cipher = SSL_get_cipher_by_value(cipher_suite);
if (cipher == NULL) {
// unknown cipher
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CIPHER_RETURNED);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// The cipher must be allowed in the selected version and enabled.
uint32_t mask_a, mask_k;
ssl_get_client_disabled(hs, &mask_a, &mask_k);
if ((cipher->algorithm_mkey & mask_k) || (cipher->algorithm_auth & mask_a) ||
SSL_CIPHER_get_min_version(cipher) > ssl_protocol_version(ssl) ||
SSL_CIPHER_get_max_version(cipher) < ssl_protocol_version(ssl) ||
!sk_SSL_CIPHER_find(SSL_get_ciphers(ssl), NULL, cipher)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CIPHER_RETURNED);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
if (ssl->session != NULL) {
if (ssl->session->ssl_version != ssl->version) {
OPENSSL_PUT_ERROR(SSL, SSL_R_OLD_SESSION_VERSION_NOT_RETURNED);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
if (ssl->session->cipher != cipher) {
OPENSSL_PUT_ERROR(SSL, SSL_R_OLD_SESSION_CIPHER_NOT_RETURNED);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
if (!ssl_session_is_context_valid(hs, ssl->session.get())) {
// This is actually a client application bug.
OPENSSL_PUT_ERROR(SSL,
SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
} else {
hs->new_session->cipher = cipher;
}
hs->new_cipher = cipher;
// Now that the cipher is known, initialize the handshake hash and hash the
// ServerHello.
if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher) ||
!ssl_hash_message(hs, msg)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
// If doing a full handshake, the server may request a client certificate
// which requires hashing the handshake transcript. Otherwise, the handshake
// buffer may be released.
if (ssl->session != NULL ||
!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->transcript.FreeBuffer();
}
// Only the NULL compression algorithm is supported.
if (compression_method != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_COMPRESSION_ALGORITHM);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// TLS extensions
if (!ssl_parse_serverhello_tlsext(hs, &server_hello)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
return ssl_hs_error;
}
// There should be nothing left over in the record.
if (CBS_len(&server_hello) != 0) {
// wrong packet length
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
if (ssl->session != NULL &&
hs->extended_master_secret != ssl->session->extended_master_secret) {
if (ssl->session->extended_master_secret) {
OPENSSL_PUT_ERROR(SSL, SSL_R_RESUMED_EMS_SESSION_WITHOUT_EMS_EXTENSION);
} else {
OPENSSL_PUT_ERROR(SSL, SSL_R_RESUMED_NON_EMS_SESSION_WITH_EMS_EXTENSION);
}
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
if (ssl->s3->token_binding_negotiated &&
(!hs->extended_master_secret || !ssl->s3->send_connection_binding)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_TB_WITHOUT_EMS_OR_RI);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
if (ssl->session != NULL) {
if (ssl->ctx->reverify_on_resume &&
ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->state = state_reverify_server_certificate;
} else {
hs->state = state_read_session_ticket;
}
return ssl_hs_ok;
}
hs->state = state_read_server_certificate;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_tls13(SSL_HANDSHAKE *hs) {
enum ssl_hs_wait_t wait = tls13_client_handshake(hs);
if (wait == ssl_hs_ok) {
hs->state = state_finish_client_handshake;
return ssl_hs_ok;
}
return wait;
}
static enum ssl_hs_wait_t do_read_server_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->state = state_read_certificate_status;
return ssl_hs_ok;
}
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
CBS body = msg.body;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_parse_cert_chain(&alert, &hs->new_session->certs, &hs->peer_pubkey,
NULL, &body, ssl->ctx->pool)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (sk_CRYPTO_BUFFER_num(hs->new_session->certs.get()) == 0 ||
CBS_len(&body) != 0 ||
!ssl->ctx->x509_method->session_cache_objects(hs->new_session.get())) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
if (!ssl_check_leaf_certificate(
hs, hs->peer_pubkey.get(),
sk_CRYPTO_BUFFER_value(hs->new_session->certs.get(), 0))) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->state = state_read_certificate_status;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_certificate_status(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!hs->certificate_status_expected) {
hs->state = state_verify_server_certificate;
return ssl_hs_ok;
}
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (msg.type != SSL3_MT_CERTIFICATE_STATUS) {
// A server may send status_request in ServerHello and then change its mind
// about sending CertificateStatus.
hs->state = state_verify_server_certificate;
return ssl_hs_ok;
}
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
CBS certificate_status = msg.body, ocsp_response;
uint8_t status_type;
if (!CBS_get_u8(&certificate_status, &status_type) ||
status_type != TLSEXT_STATUSTYPE_ocsp ||
!CBS_get_u24_length_prefixed(&certificate_status, &ocsp_response) ||
CBS_len(&ocsp_response) == 0 ||
CBS_len(&certificate_status) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
hs->new_session->ocsp_response.reset(
CRYPTO_BUFFER_new_from_CBS(&ocsp_response, ssl->ctx->pool));
if (hs->new_session->ocsp_response == nullptr) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->state = state_verify_server_certificate;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_verify_server_certificate(SSL_HANDSHAKE *hs) {
if (!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->state = state_read_server_key_exchange;
return ssl_hs_ok;
}
switch (ssl_verify_peer_cert(hs)) {
case ssl_verify_ok:
break;
case ssl_verify_invalid:
return ssl_hs_error;
case ssl_verify_retry:
hs->state = state_verify_server_certificate;
return ssl_hs_certificate_verify;
}
hs->state = state_read_server_key_exchange;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_reverify_server_certificate(SSL_HANDSHAKE *hs) {
assert(hs->ssl->ctx->reverify_on_resume);
switch (ssl_reverify_peer_cert(hs)) {
case ssl_verify_ok:
break;
case ssl_verify_invalid:
return ssl_hs_error;
case ssl_verify_retry:
hs->state = state_reverify_server_certificate;
return ssl_hs_certificate_verify;
}
hs->state = state_read_session_ticket;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_server_key_exchange(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (msg.type != SSL3_MT_SERVER_KEY_EXCHANGE) {
// Some ciphers (pure PSK) have an optional ServerKeyExchange message.
if (ssl_cipher_requires_server_key_exchange(hs->new_cipher)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
return ssl_hs_error;
}
hs->state = state_read_certificate_request;
return ssl_hs_ok;
}
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
uint32_t alg_k = hs->new_cipher->algorithm_mkey;
uint32_t alg_a = hs->new_cipher->algorithm_auth;
CBS server_key_exchange = msg.body;
if (alg_a & SSL_aPSK) {
CBS psk_identity_hint;
// Each of the PSK key exchanges begins with a psk_identity_hint.
if (!CBS_get_u16_length_prefixed(&server_key_exchange,
&psk_identity_hint)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
// Store the PSK identity hint for the ClientKeyExchange. Assume that the
// maximum length of a PSK identity hint can be as long as the maximum
// length of a PSK identity. Also do not allow NULL characters; identities
// are saved as C strings.
//
// TODO(davidben): Should invalid hints be ignored? It's a hint rather than
// a specific identity.
if (CBS_len(&psk_identity_hint) > PSK_MAX_IDENTITY_LEN ||
CBS_contains_zero_byte(&psk_identity_hint)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
// Save non-empty identity hints as a C string. Empty identity hints we
// treat as missing. Plain PSK makes it possible to send either no hint
// (omit ServerKeyExchange) or an empty hint, while ECDHE_PSK can only spell
// empty hint. Having different capabilities is odd, so we interpret empty
// and missing as identical.
char *raw = nullptr;
if (CBS_len(&psk_identity_hint) != 0 &&
!CBS_strdup(&psk_identity_hint, &raw)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
hs->peer_psk_identity_hint.reset(raw);
}
if (alg_k & SSL_kECDHE) {
// Parse the server parameters.
uint8_t group_type;
uint16_t group_id;
CBS point;
if (!CBS_get_u8(&server_key_exchange, &group_type) ||
group_type != NAMED_CURVE_TYPE ||
!CBS_get_u16(&server_key_exchange, &group_id) ||
!CBS_get_u8_length_prefixed(&server_key_exchange, &point)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
hs->new_session->group_id = group_id;
// Ensure the group is consistent with preferences.
if (!tls1_check_group_id(hs, group_id)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// Initialize ECDH and save the peer public key for later.
hs->key_share = SSLKeyShare::Create(group_id);
if (!hs->key_share ||
!hs->peer_key.CopyFrom(point)) {
return ssl_hs_error;
}
} else if (!(alg_k & SSL_kPSK)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
return ssl_hs_error;
}
// At this point, |server_key_exchange| contains the signature, if any, while
// |msg.body| contains the entire message. From that, derive a CBS containing
// just the parameter.
CBS parameter;
CBS_init(&parameter, CBS_data(&msg.body),
CBS_len(&msg.body) - CBS_len(&server_key_exchange));
// ServerKeyExchange should be signed by the server's public key.
if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
uint16_t signature_algorithm = 0;
if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) {
if (!CBS_get_u16(&server_key_exchange, &signature_algorithm)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!tls12_check_peer_sigalg(ssl, &alert, signature_algorithm)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
hs->new_session->peer_signature_algorithm = signature_algorithm;
} else if (!tls1_get_legacy_signature_algorithm(&signature_algorithm,
hs->peer_pubkey.get())) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_ERROR_UNSUPPORTED_CERTIFICATE_TYPE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_CERTIFICATE);
return ssl_hs_error;
}
// The last field in |server_key_exchange| is the signature.
CBS signature;
if (!CBS_get_u16_length_prefixed(&server_key_exchange, &signature) ||
CBS_len(&server_key_exchange) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
ScopedCBB transcript;
Array<uint8_t> transcript_data;
if (!CBB_init(transcript.get(),
2 * SSL3_RANDOM_SIZE + CBS_len(&parameter)) ||
!CBB_add_bytes(transcript.get(), ssl->s3->client_random,
SSL3_RANDOM_SIZE) ||
!CBB_add_bytes(transcript.get(), ssl->s3->server_random,
SSL3_RANDOM_SIZE) ||
!CBB_add_bytes(transcript.get(), CBS_data(&parameter),
CBS_len(&parameter)) ||
!CBBFinishArray(transcript.get(), &transcript_data)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
bool sig_ok = ssl_public_key_verify(ssl, signature, signature_algorithm,
hs->peer_pubkey.get(), transcript_data);
#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
sig_ok = true;
ERR_clear_error();
#endif
if (!sig_ok) {
// bad signature
OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
return ssl_hs_error;
}
} else {
// PSK ciphers are the only supported certificate-less ciphers.
assert(alg_a == SSL_aPSK);
if (CBS_len(&server_key_exchange) > 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_EXTRA_DATA_IN_MESSAGE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
}
ssl->method->next_message(ssl);
hs->state = state_read_certificate_request;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_certificate_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
hs->state = state_read_server_hello_done;
return ssl_hs_ok;
}
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (msg.type == SSL3_MT_SERVER_HELLO_DONE) {
// If we get here we don't need the handshake buffer as we won't be doing
// client auth.
hs->transcript.FreeBuffer();
hs->state = state_read_server_hello_done;
return ssl_hs_ok;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE_REQUEST) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
// Get the certificate types.
CBS body = msg.body, certificate_types;
if (!CBS_get_u8_length_prefixed(&body, &certificate_types)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
if (!hs->certificate_types.CopyFrom(certificate_types)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) {
CBS supported_signature_algorithms;
if (!CBS_get_u16_length_prefixed(&body, &supported_signature_algorithms) ||
!tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
}
uint8_t alert = SSL_AD_DECODE_ERROR;
UniquePtr<STACK_OF(CRYPTO_BUFFER)> ca_names =
ssl_parse_client_CA_list(ssl, &alert, &body);
if (!ca_names) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (CBS_len(&body) != 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
hs->cert_request = true;
hs->ca_names = std::move(ca_names);
ssl->ctx->x509_method->hs_flush_cached_ca_names(hs);
ssl->method->next_message(ssl);
hs->state = state_read_server_hello_done;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_server_hello_done(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_SERVER_HELLO_DONE) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
// ServerHelloDone is empty.
if (CBS_len(&msg.body) != 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->state = state_send_client_certificate;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_client_certificate(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// The peer didn't request a certificate.
if (!hs->cert_request) {
hs->state = state_send_client_key_exchange;
return ssl_hs_ok;
}
// Call cert_cb to update the certificate.
if (hs->config->cert->cert_cb != NULL) {
int rv = hs->config->cert->cert_cb(ssl, hs->config->cert->cert_cb_arg);
if (rv == 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR);
return ssl_hs_error;
}
if (rv < 0) {
hs->state = state_send_client_certificate;
return ssl_hs_x509_lookup;
}
}
if (!ssl_has_certificate(hs->config)) {
// Without a client certificate, the handshake buffer may be released.
hs->transcript.FreeBuffer();
}
if (!ssl_on_certificate_selected(hs) ||
!ssl_output_cert_chain(hs)) {
return ssl_hs_error;
}
hs->state = state_send_client_key_exchange;
return ssl_hs_ok;
}
static_assert(sizeof(size_t) >= sizeof(unsigned),
"size_t is smaller than unsigned");
static enum ssl_hs_wait_t do_send_client_key_exchange(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ScopedCBB cbb;
CBB body;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_CLIENT_KEY_EXCHANGE)) {
return ssl_hs_error;
}
Array<uint8_t> pms;
uint32_t alg_k = hs->new_cipher->algorithm_mkey;
uint32_t alg_a = hs->new_cipher->algorithm_auth;
// If using a PSK key exchange, prepare the pre-shared key.
unsigned psk_len = 0;
uint8_t psk[PSK_MAX_PSK_LEN];
if (alg_a & SSL_aPSK) {
if (hs->config->psk_client_callback == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_NO_CLIENT_CB);
return ssl_hs_error;
}
char identity[PSK_MAX_IDENTITY_LEN + 1];
OPENSSL_memset(identity, 0, sizeof(identity));
psk_len = hs->config->psk_client_callback(
ssl, hs->peer_psk_identity_hint.get(), identity, sizeof(identity), psk,
sizeof(psk));
if (psk_len == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
assert(psk_len <= PSK_MAX_PSK_LEN);
hs->new_session->psk_identity.reset(BUF_strdup(identity));
if (hs->new_session->psk_identity == nullptr) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return ssl_hs_error;
}
// Write out psk_identity.
CBB child;
if (!CBB_add_u16_length_prefixed(&body, &child) ||
!CBB_add_bytes(&child, (const uint8_t *)identity,
OPENSSL_strnlen(identity, sizeof(identity))) ||
!CBB_flush(&body)) {
return ssl_hs_error;
}
}
// Depending on the key exchange method, compute |pms|.
if (alg_k & SSL_kRSA) {
if (!pms.Init(SSL_MAX_MASTER_KEY_LENGTH)) {
return ssl_hs_error;
}
RSA *rsa = EVP_PKEY_get0_RSA(hs->peer_pubkey.get());
if (rsa == NULL) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
pms[0] = hs->client_version >> 8;
pms[1] = hs->client_version & 0xff;
if (!RAND_bytes(&pms[2], SSL_MAX_MASTER_KEY_LENGTH - 2)) {
return ssl_hs_error;
}
CBB enc_pms;
uint8_t *ptr;
size_t enc_pms_len;
if (!CBB_add_u16_length_prefixed(&body, &enc_pms) ||
!CBB_reserve(&enc_pms, &ptr, RSA_size(rsa)) ||
!RSA_encrypt(rsa, &enc_pms_len, ptr, RSA_size(rsa), pms.data(),
pms.size(), RSA_PKCS1_PADDING) ||
!CBB_did_write(&enc_pms, enc_pms_len) ||
!CBB_flush(&body)) {
return ssl_hs_error;
}
} else if (alg_k & SSL_kECDHE) {
// Generate a keypair and serialize the public half.
CBB child;
if (!CBB_add_u8_length_prefixed(&body, &child)) {
return ssl_hs_error;
}
// Compute the premaster.
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!hs->key_share->Accept(&child, &pms, &alert, hs->peer_key)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (!CBB_flush(&body)) {
return ssl_hs_error;
}
// The key exchange state may now be discarded.
hs->key_share.reset();
hs->peer_key.Reset();
} else if (alg_k & SSL_kPSK) {
// For plain PSK, other_secret is a block of 0s with the same length as
// the pre-shared key.
if (!pms.Init(psk_len)) {
return ssl_hs_error;
}
OPENSSL_memset(pms.data(), 0, pms.size());
} else {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
// For a PSK cipher suite, other_secret is combined with the pre-shared
// key.
if (alg_a & SSL_aPSK) {
ScopedCBB pms_cbb;
CBB child;
if (!CBB_init(pms_cbb.get(), 2 + psk_len + 2 + pms.size()) ||
!CBB_add_u16_length_prefixed(pms_cbb.get(), &child) ||
!CBB_add_bytes(&child, pms.data(), pms.size()) ||
!CBB_add_u16_length_prefixed(pms_cbb.get(), &child) ||
!CBB_add_bytes(&child, psk, psk_len) ||
!CBBFinishArray(pms_cbb.get(), &pms)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
return ssl_hs_error;
}
}
// The message must be added to the finished hash before calculating the
// master secret.
if (!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
hs->new_session->master_key_length =
tls1_generate_master_secret(hs, hs->new_session->master_key, pms);
if (hs->new_session->master_key_length == 0) {
return ssl_hs_error;
}
hs->new_session->extended_master_secret = hs->extended_master_secret;
hs->state = state_send_client_certificate_verify;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_client_certificate_verify(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!hs->cert_request || !ssl_has_certificate(hs->config)) {
hs->state = state_send_client_finished;
return ssl_hs_ok;
}
assert(ssl_has_private_key(hs->config));
ScopedCBB cbb;
CBB body, child;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_CERTIFICATE_VERIFY)) {
return ssl_hs_error;
}
uint16_t signature_algorithm;
if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) {
// Write out the digest type in TLS 1.2.
if (!CBB_add_u16(&body, signature_algorithm)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
}
// Set aside space for the signature.
const size_t max_sig_len = EVP_PKEY_size(hs->local_pubkey.get());
uint8_t *ptr;
if (!CBB_add_u16_length_prefixed(&body, &child) ||
!CBB_reserve(&child, &ptr, max_sig_len)) {
return ssl_hs_error;
}
size_t sig_len = max_sig_len;
switch (ssl_private_key_sign(hs, ptr, &sig_len, max_sig_len,
signature_algorithm,
hs->transcript.buffer())) {
case ssl_private_key_success:
break;
case ssl_private_key_failure:
return ssl_hs_error;
case ssl_private_key_retry:
hs->state = state_send_client_certificate_verify;
return ssl_hs_private_key_operation;
}
if (!CBB_did_write(&child, sig_len) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
// The handshake buffer is no longer necessary.
hs->transcript.FreeBuffer();
hs->state = state_send_client_finished;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_client_finished(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// Resolve Channel ID first, before any non-idempotent operations.
if (ssl->s3->channel_id_valid) {
if (!ssl_do_channel_id_callback(hs)) {
return ssl_hs_error;
}
if (hs->config->channel_id_private == NULL) {
hs->state = state_send_client_finished;
return ssl_hs_channel_id_lookup;
}
}
if (!ssl->method->add_change_cipher_spec(ssl) ||
!tls1_change_cipher_state(hs, evp_aead_seal)) {
return ssl_hs_error;
}
if (hs->next_proto_neg_seen) {
static const uint8_t kZero[32] = {0};
size_t padding_len =
32 - ((ssl->s3->next_proto_negotiated.size() + 2) % 32);
ScopedCBB cbb;
CBB body, child;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_NEXT_PROTO) ||
!CBB_add_u8_length_prefixed(&body, &child) ||
!CBB_add_bytes(&child, ssl->s3->next_proto_negotiated.data(),
ssl->s3->next_proto_negotiated.size()) ||
!CBB_add_u8_length_prefixed(&body, &child) ||
!CBB_add_bytes(&child, kZero, padding_len) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
}
if (ssl->s3->channel_id_valid) {
ScopedCBB cbb;
CBB body;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CHANNEL_ID) ||
!tls1_write_channel_id(hs, &body) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
}
if (!ssl_send_finished(hs)) {
return ssl_hs_error;
}
hs->state = state_finish_flight;
return ssl_hs_flush;
}
static bool can_false_start(const SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// False Start bypasses the Finished check's downgrade protection. This can
// enable attacks where we send data under weaker settings than supported
// (e.g. the Logjam attack). Thus we require TLS 1.2 with an ECDHE+AEAD
// cipher, our strongest settings before TLS 1.3.
//
// Now that TLS 1.3 exists, we would like to avoid similar attacks between
// TLS 1.2 and TLS 1.3, but there are too many TLS 1.2 deployments to
// sacrifice False Start on them. TLS 1.3's downgrade signal fixes this, but
// |SSL_CTX_set_ignore_tls13_downgrade| can disable it due to compatibility
// issues.
//
// |SSL_CTX_set_ignore_tls13_downgrade| normally still retains Finished-based
// downgrade protection, but False Start bypasses that. Thus, we disable False
// Start based on the TLS 1.3 downgrade signal, even if otherwise unenforced.
if (SSL_is_dtls(ssl) ||
SSL_version(ssl) != TLS1_2_VERSION ||
hs->new_cipher->algorithm_mkey != SSL_kECDHE ||
hs->new_cipher->algorithm_mac != SSL_AEAD ||
ssl->s3->tls13_downgrade) {
return false;
}
// Additionally require ALPN or NPN by default.
//
// TODO(davidben): Can this constraint be relaxed globally now that cipher
// suite requirements have been tightened?
if (!ssl->ctx->false_start_allowed_without_alpn &&
ssl->s3->alpn_selected.empty() &&
ssl->s3->next_proto_negotiated.empty()) {
return false;
}
return true;
}
static enum ssl_hs_wait_t do_finish_flight(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (ssl->session != NULL) {
hs->state = state_finish_client_handshake;
return ssl_hs_ok;
}
// This is a full handshake. If it involves ChannelID, then record the
// handshake hashes at this point in the session so that any resumption of
// this session with ChannelID can sign those hashes.
if (!tls1_record_handshake_hashes_for_channel_id(hs)) {
return ssl_hs_error;
}
hs->state = state_read_session_ticket;
if ((SSL_get_mode(ssl) & SSL_MODE_ENABLE_FALSE_START) &&
can_false_start(hs) &&
// No False Start on renegotiation (would complicate the state machine).
!ssl->s3->initial_handshake_complete) {
hs->in_false_start = true;
hs->can_early_write = true;
return ssl_hs_early_return;
}
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_session_ticket(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (!hs->ticket_expected) {
hs->state = state_process_change_cipher_spec;
return ssl_hs_read_change_cipher_spec;
}
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_NEW_SESSION_TICKET) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
CBS new_session_ticket = msg.body, ticket;
uint32_t ticket_lifetime_hint;
if (!CBS_get_u32(&new_session_ticket, &ticket_lifetime_hint) ||
!CBS_get_u16_length_prefixed(&new_session_ticket, &ticket) ||
CBS_len(&new_session_ticket) != 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
if (CBS_len(&ticket) == 0) {
// RFC 5077 allows a server to change its mind and send no ticket after
// negotiating the extension. The value of |ticket_expected| is checked in
// |ssl_update_cache| so is cleared here to avoid an unnecessary update.
hs->ticket_expected = false;
ssl->method->next_message(ssl);
hs->state = state_process_change_cipher_spec;
return ssl_hs_read_change_cipher_spec;
}
SSL_SESSION *session = hs->new_session.get();
UniquePtr<SSL_SESSION> renewed_session;
if (ssl->session != NULL) {
// The server is sending a new ticket for an existing session. Sessions are
// immutable once established, so duplicate all but the ticket of the
// existing session.
renewed_session =
SSL_SESSION_dup(ssl->session.get(), SSL_SESSION_INCLUDE_NONAUTH);
if (!renewed_session) {
// This should never happen.
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
session = renewed_session.get();
}
// |ticket_lifetime_hint| is measured from when the ticket was issued.
ssl_session_rebase_time(ssl, session);
if (!session->ticket.CopyFrom(ticket)) {
return ssl_hs_error;
}
session->ticket_lifetime_hint = ticket_lifetime_hint;
// Generate a session ID for this session based on the session ticket. We use
// the session ID mechanism for detecting ticket resumption. This also fits in
// with assumptions elsewhere in OpenSSL.
if (!EVP_Digest(CBS_data(&ticket), CBS_len(&ticket),
session->session_id, &session->session_id_length,
EVP_sha256(), NULL)) {
return ssl_hs_error;
}
if (renewed_session) {
session->not_resumable = false;
ssl->session = std::move(renewed_session);
}
ssl->method->next_message(ssl);
hs->state = state_process_change_cipher_spec;
return ssl_hs_read_change_cipher_spec;
}
static enum ssl_hs_wait_t do_process_change_cipher_spec(SSL_HANDSHAKE *hs) {
if (!tls1_change_cipher_state(hs, evp_aead_open)) {
return ssl_hs_error;
}
hs->state = state_read_server_finished;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_server_finished(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
enum ssl_hs_wait_t wait = ssl_get_finished(hs);
if (wait != ssl_hs_ok) {
return wait;
}
if (ssl->session != NULL) {
hs->state = state_send_client_finished;
return ssl_hs_ok;
}
hs->state = state_finish_client_handshake;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_finish_client_handshake(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ssl->method->on_handshake_complete(ssl);
if (ssl->session != NULL) {
ssl->s3->established_session = UpRef(ssl->session);
} else {
// We make a copy of the session in order to maintain the immutability
// of the new established_session due to False Start. The caller may
// have taken a reference to the temporary session.
ssl->s3->established_session =
SSL_SESSION_dup(hs->new_session.get(), SSL_SESSION_DUP_ALL);
if (!ssl->s3->established_session) {
return ssl_hs_error;
}
// Renegotiations do not participate in session resumption.
if (!ssl->s3->initial_handshake_complete) {
ssl->s3->established_session->not_resumable = false;
}
hs->new_session.reset();
}
hs->handshake_finalized = true;
ssl->s3->initial_handshake_complete = true;
ssl_update_cache(hs, SSL_SESS_CACHE_CLIENT);
hs->state = state_done;
return ssl_hs_ok;
}
enum ssl_hs_wait_t ssl_client_handshake(SSL_HANDSHAKE *hs) {
while (hs->state != state_done) {
enum ssl_hs_wait_t ret = ssl_hs_error;
enum ssl_client_hs_state_t state =
static_cast<enum ssl_client_hs_state_t>(hs->state);
switch (state) {
case state_start_connect:
ret = do_start_connect(hs);
break;
case state_enter_early_data:
ret = do_enter_early_data(hs);
break;
case state_read_hello_verify_request:
ret = do_read_hello_verify_request(hs);
break;
case state_read_server_hello:
ret = do_read_server_hello(hs);
break;
case state_tls13:
ret = do_tls13(hs);
break;
case state_read_server_certificate:
ret = do_read_server_certificate(hs);
break;
case state_read_certificate_status:
ret = do_read_certificate_status(hs);
break;
case state_verify_server_certificate:
ret = do_verify_server_certificate(hs);
break;
case state_reverify_server_certificate:
ret = do_reverify_server_certificate(hs);
break;
case state_read_server_key_exchange:
ret = do_read_server_key_exchange(hs);
break;
case state_read_certificate_request:
ret = do_read_certificate_request(hs);
break;
case state_read_server_hello_done:
ret = do_read_server_hello_done(hs);
break;
case state_send_client_certificate:
ret = do_send_client_certificate(hs);
break;
case state_send_client_key_exchange:
ret = do_send_client_key_exchange(hs);
break;
case state_send_client_certificate_verify:
ret = do_send_client_certificate_verify(hs);
break;
case state_send_client_finished:
ret = do_send_client_finished(hs);
break;
case state_finish_flight:
ret = do_finish_flight(hs);
break;
case state_read_session_ticket:
ret = do_read_session_ticket(hs);
break;
case state_process_change_cipher_spec:
ret = do_process_change_cipher_spec(hs);
break;
case state_read_server_finished:
ret = do_read_server_finished(hs);
break;
case state_finish_client_handshake:
ret = do_finish_client_handshake(hs);
break;
case state_done:
ret = ssl_hs_ok;
break;
}
if (hs->state != state) {
ssl_do_info_callback(hs->ssl, SSL_CB_CONNECT_LOOP, 1);
}
if (ret != ssl_hs_ok) {
return ret;
}
}
ssl_do_info_callback(hs->ssl, SSL_CB_HANDSHAKE_DONE, 1);
return ssl_hs_ok;
}
const char *ssl_client_handshake_state(SSL_HANDSHAKE *hs) {
enum ssl_client_hs_state_t state =
static_cast<enum ssl_client_hs_state_t>(hs->state);
switch (state) {
case state_start_connect:
return "TLS client start_connect";
case state_enter_early_data:
return "TLS client enter_early_data";
case state_read_hello_verify_request:
return "TLS client read_hello_verify_request";
case state_read_server_hello:
return "TLS client read_server_hello";
case state_tls13:
return tls13_client_handshake_state(hs);
case state_read_server_certificate:
return "TLS client read_server_certificate";
case state_read_certificate_status:
return "TLS client read_certificate_status";
case state_verify_server_certificate:
return "TLS client verify_server_certificate";
case state_reverify_server_certificate:
return "TLS client reverify_server_certificate";
case state_read_server_key_exchange:
return "TLS client read_server_key_exchange";
case state_read_certificate_request:
return "TLS client read_certificate_request";
case state_read_server_hello_done:
return "TLS client read_server_hello_done";
case state_send_client_certificate:
return "TLS client send_client_certificate";
case state_send_client_key_exchange:
return "TLS client send_client_key_exchange";
case state_send_client_certificate_verify:
return "TLS client send_client_certificate_verify";
case state_send_client_finished:
return "TLS client send_client_finished";
case state_finish_flight:
return "TLS client finish_flight";
case state_read_session_ticket:
return "TLS client read_session_ticket";
case state_process_change_cipher_spec:
return "TLS client process_change_cipher_spec";
case state_read_server_finished:
return "TLS client read_server_finished";
case state_finish_client_handshake:
return "TLS client finish_client_handshake";
case state_done:
return "TLS client done";
}
return "TLS client unknown";
}
}
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