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handshake_client.cc
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// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
// Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved.
// Copyright 2005 Nokia. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <openssl/ssl.h>
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <algorithm>
#include <utility>
#include <openssl/aead.h>
#include <openssl/bn.h>
#include <openssl/bytestring.h>
#include <openssl/ec_key.h>
#include <openssl/ecdsa.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hpke.h>
#include <openssl/md5.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/sha.h>
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
enum ssl_client_hs_state_t {
state_start_connect = 0,
state_enter_early_data,
state_early_reverify_server_certificate,
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(const 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 bool ssl_add_tls13_cipher(CBB *cbb, uint16_t cipher_id,
ssl_compliance_policy_t policy) {
if (ssl_tls13_cipher_meets_policy(cipher_id, policy)) {
return CBB_add_u16(cbb, cipher_id);
}
return true;
}
static bool ssl_write_client_cipher_list(const SSL_HANDSHAKE *hs, CBB *out,
ssl_client_hello_type_t type) {
const 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 false;
}
// Add a fake cipher suite. See RFC 8701.
if (ssl->ctx->grease_enabled &&
!CBB_add_u16(&child, ssl_get_grease_value(hs, ssl_grease_cipher))) {
return false;
}
// Add TLS 1.3 ciphers. Order ChaCha20-Poly1305 relative to AES-GCM based on
// hardware support.
if (hs->max_version >= TLS1_3_VERSION) {
static const uint16_t kCiphersNoAESHardware[] = {
TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xffff,
TLS1_3_CK_AES_128_GCM_SHA256 & 0xffff,
TLS1_3_CK_AES_256_GCM_SHA384 & 0xffff,
};
static const uint16_t kCiphersAESHardware[] = {
TLS1_3_CK_AES_128_GCM_SHA256 & 0xffff,
TLS1_3_CK_AES_256_GCM_SHA384 & 0xffff,
TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xffff,
};
static const uint16_t kCiphersCNSA[] = {
TLS1_3_CK_AES_256_GCM_SHA384 & 0xffff,
TLS1_3_CK_AES_128_GCM_SHA256 & 0xffff,
TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xffff,
};
const bool has_aes_hw = ssl->config->aes_hw_override
? ssl->config->aes_hw_override_value
: EVP_has_aes_hardware();
const bssl::Span<const uint16_t> ciphers =
ssl->config->compliance_policy == ssl_compliance_policy_cnsa_202407
? bssl::Span<const uint16_t>(kCiphersCNSA)
: (has_aes_hw ? bssl::Span<const uint16_t>(kCiphersAESHardware)
: bssl::Span<const uint16_t>(kCiphersNoAESHardware));
for (auto cipher : ciphers) {
if (!ssl_add_tls13_cipher(&child, cipher,
ssl->config->compliance_policy)) {
return false;
}
}
}
if (hs->min_version < TLS1_3_VERSION && type != ssl_client_hello_inner) {
bool any_enabled = false;
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 = true;
if (!CBB_add_u16(&child, SSL_CIPHER_get_protocol_id(cipher))) {
return false;
}
}
// 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 false;
}
}
if (ssl->mode & SSL_MODE_SEND_FALLBACK_SCSV) {
if (!CBB_add_u16(&child, SSL3_CK_FALLBACK_SCSV & 0xffff)) {
return false;
}
}
return CBB_flush(out);
}
bool ssl_write_client_hello_without_extensions(const SSL_HANDSHAKE *hs,
CBB *cbb,
ssl_client_hello_type_t type,
bool empty_session_id) {
const SSL *const ssl = hs->ssl;
CBB child;
if (!CBB_add_u16(cbb, hs->client_version) ||
!CBB_add_bytes(cbb,
type == ssl_client_hello_inner ? hs->inner_client_random
: ssl->s3->client_random,
SSL3_RANDOM_SIZE) ||
!CBB_add_u8_length_prefixed(cbb, &child)) {
return false;
}
// Do not send a session ID on renegotiation.
if (!ssl->s3->initial_handshake_complete && //
!empty_session_id && //
!CBB_add_bytes(&child, hs->session_id.data(), hs->session_id.size())) {
return false;
}
if (SSL_is_dtls(ssl)) {
if (!CBB_add_u8_length_prefixed(cbb, &child) ||
!CBB_add_bytes(&child, hs->dtls_cookie.data(),
hs->dtls_cookie.size())) {
return false;
}
}
if (!ssl_write_client_cipher_list(hs, cbb, type) ||
!CBB_add_u8(cbb, 1 /* one compression method */) ||
!CBB_add_u8(cbb, 0 /* null compression */)) {
return false;
}
return true;
}
bool ssl_add_client_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
ScopedCBB cbb;
CBB body;
ssl_client_hello_type_t type = hs->selected_ech_config
? ssl_client_hello_outer
: ssl_client_hello_unencrypted;
bool needs_psk_binder;
Array<uint8_t> msg;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CLIENT_HELLO) ||
!ssl_write_client_hello_without_extensions(hs, &body, type,
/*empty_session_id=*/false) ||
!ssl_add_clienthello_tlsext(hs, &body, /*out_encoded=*/nullptr,
&needs_psk_binder, type, CBB_len(&body)) ||
!ssl->method->finish_message(ssl, cbb.get(), &msg)) {
return false;
}
// Now that the length prefixes have been computed, fill in the placeholder
// PSK binder.
if (needs_psk_binder) {
// ClientHelloOuter cannot have a PSK binder. Otherwise the
// ClientHellOuterAAD computation would break.
assert(type != ssl_client_hello_outer);
if (!tls13_write_psk_binder(hs, hs->transcript, Span(msg),
/*out_binder_len=*/0)) {
return false;
}
}
return ssl->method->add_message(ssl, std::move(msg));
}
static bool parse_server_version(const SSL_HANDSHAKE *hs, uint16_t *out_version,
uint8_t *out_alert,
const ParsedServerHello &server_hello) {
uint16_t legacy_version = TLS1_2_VERSION;
if (SSL_is_dtls(hs->ssl)) {
legacy_version = DTLS1_2_VERSION;
}
// If the outer version is not TLS 1.2, use it.
// TODO(davidben): This function doesn't quite match the RFC8446 formulation.
if (server_hello.legacy_version != legacy_version) {
*out_version = server_hello.legacy_version;
return true;
}
SSLExtension supported_versions(TLSEXT_TYPE_supported_versions);
CBS extensions = server_hello.extensions;
if (!ssl_parse_extensions(&extensions, out_alert, {&supported_versions},
/*ignore_unknown=*/true)) {
return false;
}
if (!supported_versions.present) {
*out_version = server_hello.legacy_version;
return true;
}
if (!CBS_get_u16(&supported_versions.data, out_version) || //
CBS_len(&supported_versions.data) != 0) {
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
return true;
}
// should_offer_early_data returns |ssl_early_data_accepted| if |hs| should
// offer early data, and some other reason code otherwise.
static ssl_early_data_reason_t should_offer_early_data(
const SSL_HANDSHAKE *hs) {
const SSL *const ssl = hs->ssl;
assert(!ssl->server);
if (!ssl->enable_early_data) {
return ssl_early_data_disabled;
}
if (hs->max_version < TLS1_3_VERSION || SSL_is_dtls(ssl)) {
// We discard inapplicable sessions, so this is redundant with the session
// checks below, but reporting that TLS 1.3 was disabled is more useful.
//
// TODO(crbug.com/381113363): Support early data in DTLS 1.3.
return ssl_early_data_protocol_version;
}
if (ssl->session == nullptr) {
return ssl_early_data_no_session_offered;
}
if (ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION ||
ssl->session->ticket_max_early_data == 0) {
return ssl_early_data_unsupported_for_session;
}
if (!ssl->session->early_alpn.empty()) {
if (!ssl_is_alpn_protocol_allowed(hs, ssl->session->early_alpn)) {
// Avoid reporting a confusing value in |SSL_get0_alpn_selected|.
return ssl_early_data_alpn_mismatch;
}
// If the previous connection negotiated ALPS, only offer 0-RTT when the
// local are settings are consistent with what we'd offer for this
// connection.
if (ssl->session->has_application_settings) {
Span<const uint8_t> settings;
if (!ssl_get_local_application_settings(hs, &settings,
ssl->session->early_alpn) ||
settings != ssl->session->local_application_settings) {
return ssl_early_data_alps_mismatch;
}
}
}
// Early data has not yet been accepted, but we use it as a success code.
return ssl_early_data_accepted;
}
void ssl_done_writing_client_hello(SSL_HANDSHAKE *hs) {
hs->ech_client_outer.Reset();
hs->cookie.Reset();
hs->key_share_bytes.Reset();
hs->pake_share_bytes.Reset();
}
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;
}
uint8_t ech_enc[EVP_HPKE_MAX_ENC_LENGTH];
size_t ech_enc_len;
if (!ssl_select_ech_config(hs, ech_enc, &ech_enc_len)) {
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 (!ssl_setup_pake_shares(hs)) {
return ssl_hs_error;
}
// If the configured session has expired or is not usable, drop it. We also do
// not offer sessions on renegotiation.
SSLSessionType session_type = SSLSessionType::kNotResumable;
if (ssl->session != nullptr) {
session_type = ssl_session_get_type(ssl->session.get());
if (ssl->session->is_server ||
!ssl_supports_version(hs, ssl->session->ssl_version) ||
// Do not offer TLS 1.2 sessions with ECH. ClientHelloInner does not
// offer TLS 1.2, and the cleartext session ID may leak the server
// identity.
(hs->selected_ech_config &&
ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) ||
session_type == SSLSessionType::kNotResumable ||
// Don't offer TLS 1.2 tickets if disabled.
(session_type == SSLSessionType::kTicket &&
(SSL_get_options(ssl) & SSL_OP_NO_TICKET)) ||
// Don't offer sessions and PAKEs at the same time. We do not currently
// support resumption with PAKEs. (Offering both together would need
// more logic to conditionally send the key_share extension.)
hs->pake_prover != nullptr ||
!ssl_session_is_time_valid(ssl, ssl->session.get()) ||
SSL_is_quic(ssl) != int{ssl->session->is_quic} ||
ssl->s3->initial_handshake_complete) {
ssl_set_session(ssl, nullptr);
session_type = SSLSessionType::kNotResumable;
}
}
if (!RAND_bytes(ssl->s3->client_random, sizeof(ssl->s3->client_random))) {
return ssl_hs_error;
}
if (hs->selected_ech_config &&
!RAND_bytes(hs->inner_client_random, sizeof(hs->inner_client_random))) {
return ssl_hs_error;
}
// Compatibility mode sends a random session ID. Compatibility mode is
// enabled for TLS 1.3, but not when it's run over QUIC or DTLS.
const bool enable_compatibility_mode = hs->max_version >= TLS1_3_VERSION &&
!SSL_is_quic(ssl) && !SSL_is_dtls(ssl);
if (session_type == SSLSessionType::kID) {
hs->session_id = ssl->session->session_id;
} else if (session_type == SSLSessionType::kTicket ||
enable_compatibility_mode) {
// TLS 1.2 session tickets require a placeholder value to signal resumption.
hs->session_id.ResizeForOverwrite(SSL_MAX_SSL_SESSION_ID_LENGTH);
if (!RAND_bytes(hs->session_id.data(), hs->session_id.size())) {
return ssl_hs_error;
}
}
ssl_early_data_reason_t reason = should_offer_early_data(hs);
if (reason != ssl_early_data_accepted) {
ssl->s3->early_data_reason = reason;
} else {
hs->early_data_offered = true;
}
if (!ssl_setup_key_shares(hs, /*override_group_id=*/0) ||
!ssl_setup_extension_permutation(hs) ||
!ssl_encrypt_client_hello(hs, Span(ech_enc, ech_enc_len)) ||
!ssl_add_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 (!hs->early_data_offered) {
hs->state = state_read_server_hello;
return ssl_hs_ok;
}
// Stash the early data session and activate the early version. This must
// happen before |do_early_reverify_server_certificate|, so early connection
// properties are available to the callback. Note the early version may be
// overwritten later by the final version.
hs->early_session = UpRef(ssl->session);
ssl->s3->version = hs->early_session->ssl_version;
hs->is_early_version = true;
hs->state = state_early_reverify_server_certificate;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_early_reverify_server_certificate(
SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (ssl->ctx->reverify_on_resume) {
// Don't send an alert on error. The alert would be in the clear, which the
// server is not expecting anyway. Alerts in between ClientHello and
// ServerHello cannot usefully be delivered in TLS 1.3.
//
// TODO(davidben): The client behavior should be to verify the certificate
// before deciding whether to offer the session and, if invalid, decline to
// send the session.
switch (ssl_reverify_peer_cert(hs, /*send_alert=*/false)) {
case ssl_verify_ok:
break;
case ssl_verify_invalid:
return ssl_hs_error;
case ssl_verify_retry:
hs->state = state_early_reverify_server_certificate;
return ssl_hs_certificate_verify;
}
}
if (!ssl->method->add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
// Defer releasing the 0-RTT key to after certificate reverification, so the
// QUIC implementation does not accidentally write data too early.
if (!tls13_init_early_key_schedule(hs, hs->early_session.get()) ||
!tls13_derive_early_secret(hs) ||
!tls13_set_traffic_key(hs->ssl, ssl_encryption_early_data, evp_aead_seal,
hs->early_session.get(),
hs->early_traffic_secret)) {
return ssl_hs_error;
}
hs->in_early_data = true;
hs->can_early_write = true;
hs->state = state_read_server_hello;
return ssl_hs_early_return;
}
static bool handle_hello_verify_request(SSL_HANDSHAKE *hs,
const SSLMessage &msg) {
SSL *const ssl = hs->ssl;
assert(SSL_is_dtls(ssl));
assert(msg.type == DTLS1_MT_HELLO_VERIFY_REQUEST);
assert(!hs->received_hello_verify_request);
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(&hello_verify_request) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return false;
}
if (!hs->dtls_cookie.CopyFrom(cookie)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return false;
}
hs->received_hello_verify_request = true;
ssl->method->next_message(ssl);
// DTLS resets the handshake buffer after HelloVerifyRequest.
if (!hs->transcript.Init()) {
return false;
}
return ssl_add_client_hello(hs);
}
bool ssl_parse_server_hello(ParsedServerHello *out, uint8_t *out_alert,
const SSLMessage &msg) {
if (msg.type != SSL3_MT_SERVER_HELLO) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
*out_alert = SSL_AD_UNEXPECTED_MESSAGE;
return false;
}
out->raw = msg.raw;
CBS body = msg.body;
if (!CBS_get_u16(&body, &out->legacy_version) ||
!CBS_get_bytes(&body, &out->random, SSL3_RANDOM_SIZE) ||
!CBS_get_u8_length_prefixed(&body, &out->session_id) ||
CBS_len(&out->session_id) > SSL3_SESSION_ID_SIZE ||
!CBS_get_u16(&body, &out->cipher_suite) ||
!CBS_get_u8(&body, &out->compression_method)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
// In TLS 1.2 and below, empty extensions blocks may be omitted. In TLS 1.3,
// ServerHellos always have extensions, so this can be applied generically.
CBS_init(&out->extensions, nullptr, 0);
if ((CBS_len(&body) != 0 &&
!CBS_get_u16_length_prefixed(&body, &out->extensions)) ||
CBS_len(&body) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
return true;
}
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_is_dtls(ssl) && !hs->received_hello_verify_request &&
msg.type == DTLS1_MT_HELLO_VERIFY_REQUEST) {
if (!handle_hello_verify_request(hs, msg)) {
return ssl_hs_error;
}
hs->received_hello_verify_request = true;
hs->state = state_read_server_hello;
return ssl_hs_flush;
}
ParsedServerHello server_hello;
uint16_t server_version;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_parse_server_hello(&server_hello, &alert, msg) ||
!parse_server_version(hs, &server_version, &alert, server_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
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;
}
if (!ssl->s3->initial_handshake_complete) {
// |ssl->s3->version| may be set due to 0-RTT. If it was to a different
// value, the check below will fire.
assert(ssl->s3->version == 0 ||
(hs->is_early_version &&
ssl->s3->version == hs->early_session->ssl_version));
ssl->s3->version = server_version;
hs->is_early_version = false;
} else if (server_version != ssl->s3->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 the version did not match, stop sending 0-RTT data.
if (hs->early_data_offered &&
ssl->s3->version != hs->early_session->ssl_version) {
// This is currently only possible by reading a TLS 1.2 (or earlier)
// ServerHello in response to TLS 1.3. If there is ever a TLS 1.4, or
// another variant of TLS 1.3, the fatal error below will need to be a clean
// 0-RTT reject.
assert(ssl_protocol_version(ssl) < TLS1_3_VERSION);
assert(ssl_session_protocol_version(hs->early_session.get()) >=
TLS1_3_VERSION);
// A TLS 1.2 server would not know to skip the early data we offered, so
// there is no point in continuing the handshake. Report an error code as
// soon as we detect this. The caller may use this error code to implement
// the fallback described in RFC 8446 appendix D.3.
//
// Disconnect early writes. This ensures subsequent |SSL_write| calls query
// the handshake which, in turn, will replay the error code rather than fail
// at the |write_shutdown| check. See https://crbug.com/1078515.
// TODO(davidben): Should all handshake errors do this? What about record
// decryption failures?
//
// TODO(crbug.com/381113363): Although missing from the spec, a DTLS 1.2
// server will already naturally skip 0-RTT data. If we implement DTLS 1.3
// 0-RTT, we may want a clean reject.
assert(!SSL_is_dtls(ssl));
hs->can_early_write = false;
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;
}
if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
if (hs->received_hello_verify_request) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_MESSAGE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_PROTOCOL_VERSION);
return ssl_hs_error;
}
hs->state = state_tls13;
return ssl_hs_ok;
}
// If this client is configured to use a PAKE, then the server must support
// TLS 1.3.
if (hs->pake_prover) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_PROTOCOL);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_PROTOCOL_VERSION);
return ssl_hs_error;
}
// Clear some TLS 1.3 state that no longer needs to be retained.
hs->key_shares[0].reset();
hs->key_shares[1].reset();
ssl_done_writing_client_hello(hs);
// TLS 1.2 handshakes cannot accept ECH.
if (hs->selected_ech_config) {
ssl->s3->ech_status = ssl_ech_rejected;
}
// Copy over the server random.
OPENSSL_memcpy(ssl->s3->server_random, CBS_data(&server_hello.random),
SSL3_RANDOM_SIZE);
// Enforce the TLS 1.3 anti-downgrade feature.
if (!ssl->s3->initial_handshake_complete &&
hs->max_version >= TLS1_3_VERSION) {
static_assert(
sizeof(kTLS12DowngradeRandom) == sizeof(kTLS13DowngradeRandom),
"downgrade signals have different size");
static_assert(
sizeof(kJDK11DowngradeRandom) == sizeof(kTLS13DowngradeRandom),
"downgrade signals have different size");
auto suffix =
Span(ssl->s3->server_random).last(sizeof(kTLS13DowngradeRandom));
if (suffix == kTLS12DowngradeRandom || suffix == kTLS13DowngradeRandom ||
suffix == kJDK11DowngradeRandom) {
OPENSSL_PUT_ERROR(SSL, SSL_R_TLS13_DOWNGRADE);
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.
const SSL_CIPHER *cipher = SSL_get_cipher_by_value(server_hello.cipher_suite);
uint32_t mask_a, mask_k;
ssl_get_client_disabled(hs, &mask_a, &mask_k);
if (cipher == nullptr || //
(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), nullptr, 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;
}
hs->new_cipher = cipher;
if (!hs->session_id.empty() &&
Span<const uint8_t>(server_hello.session_id) == hs->session_id) {
// Echoing the ClientHello session ID in TLS 1.2, whether from the session
// or a synthetic one, indicates resumption. If there was no session (or if
// the session was only offered in ECH ClientHelloInner), this was 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 (ssl->session == nullptr || ssl->s3->ech_status == ssl_ech_rejected) {
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;
}
if (ssl->session->ssl_version != ssl->s3->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 != hs->new_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;
}
// We never offer sessions on renegotiation.
assert(!ssl->s3->initial_handshake_complete);
ssl->s3->session_reused = true;
} else {
// The session wasn't resumed. Create a fresh SSL_SESSION to fill out.
ssl_set_session(ssl, NULL);
if (!ssl_get_new_session(hs)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
// Save the session ID from the server. This may be empty if the session
// isn't resumable, or if we'll receive a session ticket later. The
// ServerHello parser ensures |server_hello.session_id| is within bounds.
hs->new_session->session_id.CopyFrom(server_hello.session_id);
hs->new_session->cipher = hs->new_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 (server_hello.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;
}
if (!ssl_parse_serverhello_tlsext(hs, &server_hello.extensions)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
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;
}
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, /*send_alert=*/true)) {
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;
}