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boringssl / boringssl / 16ba372a6bb0aab4e55ca312e8e59ec6eaab7ad6 / . / ssl / tls13_client.cc
blob: e18ad11bab6212d95bc7dd73ea2027087c1ec1c0 [file] [log] [blame]
// Copyright 2016 The BoringSSL Authors
//
// 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 <utility>
#include <openssl/bytestring.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/sha2.h>
#include <openssl/stack.h>
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
enum client_hs_state_t {
state_read_hello_retry_request = 0,
state_send_second_client_hello,
state_read_server_hello,
state_read_encrypted_extensions,
state_read_certificate_request,
state_read_server_certificate,
state_read_server_certificate_verify,
state_server_certificate_reverify,
state_read_server_finished,
state_send_end_of_early_data,
state_send_client_encrypted_extensions,
state_send_client_certificate,
state_send_client_certificate_verify,
state_complete_second_flight,
state_done,
};
static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0};
// end_of_early_data closes the early data stream for |hs| and switches the
// encryption level to |level|. It returns true on success and false on error.
static bool close_early_data(SSL_HANDSHAKE *hs, ssl_encryption_level_t level) {
SSL *const ssl = hs->ssl;
assert(hs->in_early_data);
// Note |can_early_write| may already be false if |SSL_write| exceeded the
// early data write limit.
hs->can_early_write = false;
// 0-RTT write states on the client differ between TLS 1.3, DTLS 1.3, and
// QUIC. TLS 1.3 has one write encryption level at a time. 0-RTT write keys
// overwrite the null cipher and defer handshake write keys. While a
// HelloRetryRequest can cause us to rewind back to the null cipher, sequence
// numbers have no effect, so we can install a "new" null cipher.
//
// In QUIC and DTLS 1.3, 0-RTT write state cannot override or defer the normal
// write state. The two ClientHello sequence numbers must align, and handshake
// write keys must be installed early to ACK the EncryptedExtensions.
//
// TODO(crbug.com/381113363): We do not support 0-RTT in DTLS 1.3 and, in
// QUIC, the caller handles 0-RTT data, so we can skip installing 0-RTT keys
// and act as if there is one write level. Now that we're implementing
// DTLS 1.3, switch the abstraction to the DTLS/QUIC model where handshake
// keys write keys are installed immediately, but the TLS record layer
// internally waits to activate that epoch until the 0-RTT channel is closed.
if (!SSL_is_quic(ssl)) {
if (level == ssl_encryption_initial) {
bssl::UniquePtr<SSLAEADContext> null_ctx =
SSLAEADContext::CreateNullCipher();
if (!null_ctx || //
!ssl->method->set_write_state(ssl, ssl_encryption_initial,
std::move(null_ctx),
/*traffic_secret=*/{})) {
return false;
}
} else {
assert(level == ssl_encryption_handshake);
if (!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_seal,
hs->new_session.get(),
hs->client_handshake_secret)) {
return false;
}
}
} else {
assert(ssl->s3->quic_write_level == level);
}
return true;
}
static bool parse_server_hello_tls13(const SSL_HANDSHAKE *hs,
ParsedServerHello *out, uint8_t *out_alert,
const SSLMessage &msg) {
if (!ssl_parse_server_hello(out, out_alert, msg)) {
return false;
}
uint16_t expected_version =
SSL_is_dtls(hs->ssl) ? DTLS1_2_VERSION : TLS1_2_VERSION;
// DTLS 1.3 disables "compatibility mode" (RFC 8446, appendix D.4). When
// disabled, servers MUST NOT echo the legacy_session_id (RFC 9147, section
// 5). The client could have sent a session ID indicating its willingness to
// resume a DTLS 1.2 session, so just checking that the session IDs match is
// incorrect.
Span<const uint8_t> expected_session_id =
SSL_is_dtls(hs->ssl) ? Span<const uint8_t>() : Span(hs->session_id);
// RFC 8446 fixes some legacy values. Check them.
if (out->legacy_version != expected_version || //
out->compression_method != 0 ||
Span<const uint8_t>(out->session_id) != expected_session_id ||
CBS_len(&out->extensions) == 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
return true;
}
static bool is_hello_retry_request(const ParsedServerHello &server_hello) {
return Span<const uint8_t>(server_hello.random) == kHelloRetryRequest;
}
static bool check_ech_confirmation(const SSL_HANDSHAKE *hs, bool *out_accepted,
uint8_t *out_alert,
const ParsedServerHello &server_hello) {
const bool is_hrr = is_hello_retry_request(server_hello);
size_t offset;
if (is_hrr) {
// We check for an unsolicited extension when parsing all of them.
SSLExtension ech(TLSEXT_TYPE_encrypted_client_hello);
if (!ssl_parse_extensions(&server_hello.extensions, out_alert, {&ech},
/*ignore_unknown=*/true)) {
return false;
}
if (!ech.present) {
*out_accepted = false;
return true;
}
if (CBS_len(&ech.data) != ECH_CONFIRMATION_SIGNAL_LEN) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
*out_alert = SSL_AD_DECODE_ERROR;
return false;
}
offset = CBS_data(&ech.data) - CBS_data(&server_hello.raw);
} else {
offset = ssl_ech_confirmation_signal_hello_offset(hs->ssl);
}
if (!hs->selected_ech_config) {
*out_accepted = false;
return true;
}
uint8_t expected[ECH_CONFIRMATION_SIGNAL_LEN];
if (!ssl_ech_accept_confirmation(hs, expected, hs->inner_client_random,
hs->inner_transcript, is_hrr,
server_hello.raw, offset)) {
*out_alert = SSL_AD_INTERNAL_ERROR;
return false;
}
*out_accepted = CRYPTO_memcmp(CBS_data(&server_hello.raw) + offset, expected,
sizeof(expected)) == 0;
return true;
}
static enum ssl_hs_wait_t do_read_hello_retry_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
assert(ssl->s3->version != 0);
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
// Queue up a ChangeCipherSpec for whenever we next send something. This
// will be before the second ClientHello. If we offered early data, this was
// already done.
if (!hs->early_data_offered && //
!ssl->method->add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
ParsedServerHello server_hello;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!parse_server_hello_tls13(hs, &server_hello, &alert, msg)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// The cipher suite must be one we offered. We currently offer all supported
// TLS 1.3 ciphers unless policy controls limited it. So we check the version
// and that it's ok per policy.
const SSL_CIPHER *cipher = SSL_get_cipher_by_value(server_hello.cipher_suite);
if (cipher == nullptr ||
SSL_CIPHER_get_min_version(cipher) > ssl_protocol_version(ssl) ||
SSL_CIPHER_get_max_version(cipher) < ssl_protocol_version(ssl) ||
!ssl_tls13_cipher_meets_policy(SSL_CIPHER_get_protocol_id(cipher),
ssl->config->compliance_policy)) {
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;
const bool is_hrr = is_hello_retry_request(server_hello);
if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher) ||
(is_hrr && !hs->transcript.UpdateForHelloRetryRequest())) {
return ssl_hs_error;
}
if (hs->selected_ech_config) {
if (!hs->inner_transcript.InitHash(ssl_protocol_version(ssl),
hs->new_cipher) ||
(is_hrr && !hs->inner_transcript.UpdateForHelloRetryRequest())) {
return ssl_hs_error;
}
}
// Determine which ClientHello the server is responding to. Run
// |check_ech_confirmation| unconditionally, so we validate the extension
// contents.
bool ech_accepted;
if (!check_ech_confirmation(hs, &ech_accepted, &alert, server_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (hs->selected_ech_config) {
ssl->s3->ech_status = ech_accepted ? ssl_ech_accepted : ssl_ech_rejected;
}
if (!is_hrr) {
hs->tls13_state = state_read_server_hello;
return ssl_hs_ok;
}
// The ECH extension, if present, was already parsed by
// |check_ech_confirmation|.
SSLExtension cookie(TLSEXT_TYPE_cookie),
key_share(TLSEXT_TYPE_key_share, !hs->key_share_bytes.empty()),
supported_versions(TLSEXT_TYPE_supported_versions),
ech_unused(TLSEXT_TYPE_encrypted_client_hello,
hs->selected_ech_config || hs->config->ech_grease_enabled);
if (!ssl_parse_extensions(
&server_hello.extensions, &alert,
{&cookie, &key_share, &supported_versions, &ech_unused},
/*ignore_unknown=*/false)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (!cookie.present && !key_share.present) {
OPENSSL_PUT_ERROR(SSL, SSL_R_EMPTY_HELLO_RETRY_REQUEST);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
if (cookie.present) {
CBS cookie_value;
if (!CBS_get_u16_length_prefixed(&cookie.data, &cookie_value) || //
CBS_len(&cookie_value) == 0 || //
CBS_len(&cookie.data) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
if (!hs->cookie.CopyFrom(cookie_value)) {
return ssl_hs_error;
}
}
if (key_share.present) {
// If offering PAKE, we won't send key_share extensions, in which case we
// would have rejected key_share from the peer.
assert(!hs->pake_prover);
uint16_t group_id;
if (!CBS_get_u16(&key_share.data, &group_id) ||
CBS_len(&key_share.data) != 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
// The group must be supported.
if (!tls1_check_group_id(hs, group_id)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return ssl_hs_error;
}
// Check that the HelloRetryRequest does not request a key share that was
// provided in the initial ClientHello.
if (hs->key_shares[0]->GroupID() == group_id ||
(hs->key_shares[1] && hs->key_shares[1]->GroupID() == group_id)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return ssl_hs_error;
}
if (!ssl_setup_key_shares(hs, group_id)) {
return ssl_hs_error;
}
}
// Although we now know whether ClientHelloInner was used, we currently
// maintain both transcripts up to ServerHello. We could swap transcripts
// early, but then ClientHello construction and |check_ech_confirmation|
// become more complex.
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
if (ssl->s3->ech_status == ssl_ech_accepted &&
!hs->inner_transcript.Update(msg.raw)) {
return ssl_hs_error;
}
// HelloRetryRequest should be the end of the flight.
if (ssl->method->has_unprocessed_handshake_data(ssl)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESS_HANDSHAKE_DATA);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
ssl->s3->used_hello_retry_request = true;
hs->tls13_state = state_send_second_client_hello;
// 0-RTT is rejected if we receive a HelloRetryRequest.
if (hs->in_early_data) {
ssl->s3->early_data_reason = ssl_early_data_hello_retry_request;
if (!close_early_data(hs, ssl_encryption_initial)) {
return ssl_hs_error;
}
return ssl_hs_early_data_rejected;
}
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_second_client_hello(SSL_HANDSHAKE *hs) {
// Build the second ClientHelloInner, if applicable. The second ClientHello
// uses an empty string for |enc|.
if (hs->ssl->s3->ech_status == ssl_ech_accepted &&
!ssl_encrypt_client_hello(hs, {})) {
return ssl_hs_error;
}
if (!ssl_add_client_hello(hs)) {
return ssl_hs_error;
}
ssl_done_writing_client_hello(hs);
hs->tls13_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_message;
}
ParsedServerHello server_hello;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!parse_server_hello_tls13(hs, &server_hello, &alert, msg)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// Forbid a second HelloRetryRequest.
if (is_hello_retry_request(server_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
return ssl_hs_error;
}
// Check the cipher suite, in case this is after HelloRetryRequest.
if (SSL_CIPHER_get_protocol_id(hs->new_cipher) != server_hello.cipher_suite) {
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->s3->ech_status == ssl_ech_accepted) {
if (ssl->s3->used_hello_retry_request) {
// HelloRetryRequest and ServerHello must accept ECH consistently.
bool ech_accepted;
if (!check_ech_confirmation(hs, &ech_accepted, &alert, server_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
if (!ech_accepted) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INCONSISTENT_ECH_NEGOTIATION);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
}
hs->transcript = std::move(hs->inner_transcript);
hs->extensions.sent = hs->inner_extensions_sent;
// Report the inner random value through |SSL_get_client_random|.
OPENSSL_memcpy(ssl->s3->client_random, hs->inner_client_random,
SSL3_RANDOM_SIZE);
}
OPENSSL_memcpy(ssl->s3->server_random, CBS_data(&server_hello.random),
SSL3_RANDOM_SIZE);
// When offering ECH, |ssl->session| is only offered in ClientHelloInner.
const bool pre_shared_key_allowed =
ssl->session != nullptr &&
ssl_session_get_type(ssl->session.get()) ==
SSLSessionType::kPreSharedKey &&
ssl->s3->ech_status != ssl_ech_rejected;
SSLExtension key_share(TLSEXT_TYPE_key_share, hs->key_shares[0] != nullptr),
pake_share(TLSEXT_TYPE_pake, hs->pake_prover != nullptr),
pre_shared_key(TLSEXT_TYPE_pre_shared_key, pre_shared_key_allowed),
supported_versions(TLSEXT_TYPE_supported_versions);
if (!ssl_parse_extensions(
&server_hello.extensions, &alert,
{&key_share, &pre_shared_key, &supported_versions, &pake_share},
/*ignore_unknown=*/false)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// Recheck supported_versions, in case this is after HelloRetryRequest.
uint16_t version;
if (!supported_versions.present || //
!CBS_get_u16(&supported_versions.data, &version) || //
CBS_len(&supported_versions.data) != 0 || //
version != ssl->s3->version) {
OPENSSL_PUT_ERROR(SSL, SSL_R_SECOND_SERVERHELLO_VERSION_MISMATCH);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// The combination of ServerHello extensions determines the kind of handshake
// that the server selected. Check for invalid combinations.
// pake replaces key_share and may not be used with pre_shared_key.
if (pake_share.present && (key_share.present || pre_shared_key.present)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
return ssl_hs_error;
}
// In PAKE mode, we require a PAKE handshake and do not support resumption.
if (hs->pake_prover != nullptr && !pake_share.present) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION);
return ssl_hs_error;
}
// In non-PAKE modes, we require per-connection forward secrecy and do not
// support psk_ke.
if (hs->pake_prover == nullptr && !key_share.present) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION);
return ssl_hs_error;
}
// The above imples only one of three handshake forms will be allowed. The
// checks for unsolicited extensions ensure the server did not select
// something we cannot respond to.
assert(
// Full handshake
(key_share.present && !pake_share.present && !pre_shared_key.present) ||
// PSK/resumption handshake
(key_share.present && !pake_share.present && pre_shared_key.present) ||
// PAKE handshake
(!key_share.present && pake_share.present && !pre_shared_key.present));
alert = SSL_AD_DECODE_ERROR;
if (pre_shared_key.present) {
if (!ssl_ext_pre_shared_key_parse_serverhello(hs, &alert,
&pre_shared_key.data)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
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->algorithm_prf != hs->new_cipher->algorithm_prf) {
OPENSSL_PUT_ERROR(SSL, SSL_R_OLD_SESSION_PRF_HASH_MISMATCH);
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;
}
ssl->s3->session_reused = true;
hs->can_release_private_key = true;
// Only authentication information carries over in TLS 1.3.
hs->new_session =
SSL_SESSION_dup(ssl->session.get(), SSL_SESSION_DUP_AUTH_ONLY);
if (!hs->new_session) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
ssl_set_session(ssl, NULL);
// Resumption incorporates fresh key material, so refresh the timeout.
ssl_session_renew_timeout(ssl, hs->new_session.get(),
ssl->session_ctx->session_psk_dhe_timeout);
} else if (!ssl_get_new_session(hs)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
hs->new_session->cipher = hs->new_cipher;
// Set up the key schedule and incorporate the PSK into the running secret.
size_t hash_len = EVP_MD_size(
ssl_get_handshake_digest(ssl_protocol_version(ssl), hs->new_cipher));
if (!tls13_init_key_schedule(hs, ssl->s3->session_reused
? Span(hs->new_session->secret)
: Span(kZeroes, hash_len))) {
return ssl_hs_error;
}
// Resolve ECDHE or PAKE and incorporate it into the secret.
Array<uint8_t> shared_secret;
alert = SSL_AD_DECODE_ERROR;
if (key_share.present) {
if (!ssl_ext_key_share_parse_serverhello(hs, &shared_secret, &alert,
&key_share.data)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
} else if (pake_share.present) {
if (!ssl_ext_pake_parse_serverhello(hs, &shared_secret, &alert,
&pake_share.data)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
} else {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (!tls13_advance_key_schedule(hs, shared_secret) || //
!ssl_hash_message(hs, msg) || //
!tls13_derive_handshake_secrets(hs)) {
return ssl_hs_error;
}
// If currently sending early data over TCP, we defer installing client
// traffic keys to when the early data stream is closed. See
// |close_early_data|. Note if the server has already rejected 0-RTT via
// HelloRetryRequest, |in_early_data| is already false.
if (!hs->in_early_data || SSL_is_quic(ssl)) {
if (!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_seal,
hs->new_session.get(),
hs->client_handshake_secret)) {
return ssl_hs_error;
}
}
if (!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_open,
hs->new_session.get(),
hs->server_handshake_secret)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_read_encrypted_extensions;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_encrypted_extensions(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_ENCRYPTED_EXTENSIONS)) {
return ssl_hs_error;
}
CBS body = msg.body, extensions;
if (!CBS_get_u16_length_prefixed(&body, &extensions) || //
CBS_len(&body) != 0) {
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_parse_serverhello_tlsext(hs, &extensions)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
return ssl_hs_error;
}
if (ssl->s3->early_data_accepted) {
// The extension parser checks the server resumed the session.
assert(ssl->s3->session_reused);
// If offering ECH, the server may not accept early data with
// ClientHelloOuter. We do not offer sessions with ClientHelloOuter, so this
// this should be implied by checking |session_reused|.
assert(ssl->s3->ech_status != ssl_ech_rejected);
if (hs->early_session->cipher != hs->new_session->cipher) {
OPENSSL_PUT_ERROR(SSL, SSL_R_CIPHER_MISMATCH_ON_EARLY_DATA);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
if (Span(hs->early_session->early_alpn) != ssl->s3->alpn_selected) {
OPENSSL_PUT_ERROR(SSL, SSL_R_ALPN_MISMATCH_ON_EARLY_DATA);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// Channel ID is incompatible with 0-RTT. The ALPS extension should be
// negotiated implicitly.
if (hs->channel_id_negotiated ||
hs->new_session->has_application_settings) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION_ON_EARLY_DATA);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
hs->new_session->has_application_settings =
hs->early_session->has_application_settings;
if (!hs->new_session->local_application_settings.CopyFrom(
hs->early_session->local_application_settings) ||
!hs->new_session->peer_application_settings.CopyFrom(
hs->early_session->peer_application_settings)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
}
// Store the negotiated ALPN in the session.
if (!hs->new_session->early_alpn.CopyFrom(ssl->s3->alpn_selected)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_read_certificate_request;
if (hs->in_early_data && !ssl->s3->early_data_accepted) {
if (!close_early_data(hs, ssl_encryption_handshake)) {
return ssl_hs_error;
}
return ssl_hs_early_data_rejected;
}
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_certificate_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// CertificateRequest may only be sent in non-resumption handshakes.
if (ssl->s3->session_reused) {
if (ssl->ctx->reverify_on_resume && !ssl->s3->early_data_accepted) {
hs->tls13_state = state_server_certificate_reverify;
return ssl_hs_ok;
}
hs->tls13_state = state_read_server_finished;
return ssl_hs_ok;
}
if (hs->pake_prover) {
hs->tls13_state = state_read_server_finished;
return ssl_hs_ok;
}
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
// CertificateRequest is optional.
if (msg.type != SSL3_MT_CERTIFICATE_REQUEST) {
hs->tls13_state = state_read_server_certificate;
return ssl_hs_ok;
}
SSLExtension sigalgs(TLSEXT_TYPE_signature_algorithms),
ca(TLSEXT_TYPE_certificate_authorities);
CBS body = msg.body, context, extensions, supported_signature_algorithms;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!CBS_get_u8_length_prefixed(&body, &context) ||
// The request context is always empty during the handshake.
CBS_len(&context) != 0 ||
!CBS_get_u16_length_prefixed(&body, &extensions) || //
CBS_len(&body) != 0 ||
!ssl_parse_extensions(&extensions, &alert, {&sigalgs, &ca},
/*ignore_unknown=*/true) ||
!sigalgs.present ||
!CBS_get_u16_length_prefixed(&sigalgs.data,
&supported_signature_algorithms) ||
!tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return ssl_hs_error;
}
if (ca.present) {
hs->ca_names = SSL_parse_CA_list(ssl, &alert, &ca.data);
if (!hs->ca_names) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
} else {
hs->ca_names.reset(sk_CRYPTO_BUFFER_new_null());
if (!hs->ca_names) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
}
hs->cert_request = true;
ssl->ctx->x509_method->hs_flush_cached_ca_names(hs);
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_read_server_certificate;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_server_certificate(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_COMPRESSED_CERTIFICATE &&
!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE)) {
return ssl_hs_error;
}
if (!tls13_process_certificate(hs, msg, false /* certificate required */) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_read_server_certificate_verify;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_read_server_certificate_verify(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
switch (ssl_verify_peer_cert(hs)) {
case ssl_verify_ok:
break;
case ssl_verify_invalid:
return ssl_hs_error;
case ssl_verify_retry:
hs->tls13_state = state_read_server_certificate_verify;
return ssl_hs_certificate_verify;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE_VERIFY) ||
!tls13_process_certificate_verify(hs, msg) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_read_server_finished;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_server_certificate_reverify(SSL_HANDSHAKE *hs) {
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->tls13_state = state_server_certificate_reverify;
return ssl_hs_certificate_verify;
}
hs->tls13_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;
SSLMessage msg;
if (!ssl->method->get_message(ssl, &msg)) {
return ssl_hs_read_message;
}
if (!ssl_check_message_type(ssl, msg, SSL3_MT_FINISHED) ||
!tls13_process_finished(hs, msg, false /* don't use saved value */) ||
!ssl_hash_message(hs, msg) ||
// Update the secret to the master secret and derive traffic keys.
!tls13_advance_key_schedule(hs,
Span(kZeroes, hs->transcript.DigestLen())) ||
!tls13_derive_application_secrets(hs)) {
return ssl_hs_error;
}
// Finished should be the end of the flight.
if (ssl->method->has_unprocessed_handshake_data(ssl)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESS_HANDSHAKE_DATA);
return ssl_hs_error;
}
ssl->method->next_message(ssl);
hs->tls13_state = state_send_end_of_early_data;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_end_of_early_data(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (ssl->s3->early_data_accepted) {
// DTLS and QUIC omit the EndOfEarlyData message. See RFC 9001, section 8.3,
// and RFC 9147, section 5.6.
if (!SSL_is_quic(ssl) && !SSL_is_dtls(ssl)) {
ScopedCBB cbb;
CBB body;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_END_OF_EARLY_DATA) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
}
if (!close_early_data(hs, ssl_encryption_handshake)) {
return ssl_hs_error;
}
}
hs->tls13_state = state_send_client_encrypted_extensions;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_client_encrypted_extensions(
SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
// For now, only one extension uses client EncryptedExtensions. This function
// may be generalized if others use it in the future.
if (hs->new_session->has_application_settings &&
!ssl->s3->early_data_accepted) {
ScopedCBB cbb;
CBB body, extensions, extension;
uint16_t extension_type = TLSEXT_TYPE_application_settings_old;
if (hs->config->alps_use_new_codepoint) {
extension_type = TLSEXT_TYPE_application_settings;
}
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_ENCRYPTED_EXTENSIONS) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!CBB_add_u16(&extensions, extension_type) ||
!CBB_add_u16_length_prefixed(&extensions, &extension) ||
!CBB_add_bytes(&extension,
hs->new_session->local_application_settings.data(),
hs->new_session->local_application_settings.size()) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
}
hs->tls13_state = state_send_client_certificate;
return ssl_hs_ok;
}
static bool check_credential(SSL_HANDSHAKE *hs, const SSL_CREDENTIAL *cred,
uint16_t *out_sigalg) {
if (cred->type != SSLCredentialType::kX509) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CERTIFICATE_TYPE);
return false;
}
// All currently supported credentials require a signature.
if (!tls1_choose_signature_algorithm(hs, cred, out_sigalg)) {
return false;
}
// Use this credential if it either matches a requested issuer,
// or does not require issuer matching.
return ssl_credential_matches_requested_issuers(hs, cred);
}
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->tls13_state = state_complete_second_flight;
return ssl_hs_ok;
}
if (ssl->s3->ech_status == ssl_ech_rejected) {
// Do not send client certificates on ECH reject. We have not authenticated
// the server for the name that can learn the certificate.
SSL_certs_clear(ssl);
} else if (hs->config->cert->cert_cb != nullptr) {
// Call cert_cb to update the certificate.
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->tls13_state = state_send_client_certificate;
return ssl_hs_x509_lookup;
}
}
Array<SSL_CREDENTIAL *> creds;
if (!ssl_get_full_credential_list(hs, &creds)) {
return ssl_hs_error;
}
if (!creds.empty()) {
// Select the credential to use.
for (SSL_CREDENTIAL *cred : creds) {
ERR_clear_error();
uint16_t sigalg;
if (check_credential(hs, cred, &sigalg)) {
hs->credential = UpRef(cred);
hs->signature_algorithm = sigalg;
break;
}
}
if (hs->credential == nullptr) {
// The error from the last attempt is in the error queue.
assert(ERR_peek_error() != 0);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
}
if (!tls13_add_certificate(hs)) {
return ssl_hs_error;
}
hs->tls13_state = state_send_client_certificate_verify;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_client_certificate_verify(SSL_HANDSHAKE *hs) {
// Don't send CertificateVerify if there is no certificate.
if (hs->credential == nullptr) {
hs->tls13_state = state_complete_second_flight;
return ssl_hs_ok;
}
switch (tls13_add_certificate_verify(hs)) {
case ssl_private_key_success:
hs->tls13_state = state_complete_second_flight;
return ssl_hs_ok;
case ssl_private_key_retry:
hs->tls13_state = state_send_client_certificate_verify;
return ssl_hs_private_key_operation;
case ssl_private_key_failure:
return ssl_hs_error;
}
assert(0);
return ssl_hs_error;
}
static enum ssl_hs_wait_t do_complete_second_flight(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
hs->can_release_private_key = true;
// Send a Channel ID assertion if necessary.
if (hs->channel_id_negotiated) {
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())) {
return ssl_hs_error;
}
}
// Send a Finished message.
if (!tls13_add_finished(hs)) {
return ssl_hs_error;
}
// Derive the final keys and enable them.
if (!tls13_set_traffic_key(ssl, ssl_encryption_application, evp_aead_seal,
hs->new_session.get(),
hs->client_traffic_secret_0) ||
!tls13_set_traffic_key(ssl, ssl_encryption_application, evp_aead_open,
hs->new_session.get(),
hs->server_traffic_secret_0) ||
!tls13_derive_resumption_secret(hs)) {
return ssl_hs_error;
}
hs->tls13_state = state_done;
return ssl_hs_flush;
}
enum ssl_hs_wait_t tls13_client_handshake(SSL_HANDSHAKE *hs) {
while (hs->tls13_state != state_done) {
enum ssl_hs_wait_t ret = ssl_hs_error;
enum client_hs_state_t state =
static_cast<enum client_hs_state_t>(hs->tls13_state);
switch (state) {
case state_read_hello_retry_request:
ret = do_read_hello_retry_request(hs);
break;
case state_send_second_client_hello:
ret = do_send_second_client_hello(hs);
break;
case state_read_server_hello:
ret = do_read_server_hello(hs);
break;
case state_read_encrypted_extensions:
ret = do_read_encrypted_extensions(hs);
break;
case state_read_certificate_request:
ret = do_read_certificate_request(hs);
break;
case state_read_server_certificate:
ret = do_read_server_certificate(hs);
break;
case state_read_server_certificate_verify:
ret = do_read_server_certificate_verify(hs);
break;
case state_server_certificate_reverify:
ret = do_server_certificate_reverify(hs);
break;
case state_read_server_finished:
ret = do_read_server_finished(hs);
break;
case state_send_end_of_early_data:
ret = do_send_end_of_early_data(hs);
break;
case state_send_client_certificate:
ret = do_send_client_certificate(hs);
break;
case state_send_client_encrypted_extensions:
ret = do_send_client_encrypted_extensions(hs);
break;
case state_send_client_certificate_verify:
ret = do_send_client_certificate_verify(hs);
break;
case state_complete_second_flight:
ret = do_complete_second_flight(hs);
break;
case state_done:
ret = ssl_hs_ok;
break;
}
if (hs->tls13_state != state) {
ssl_do_info_callback(hs->ssl, SSL_CB_CONNECT_LOOP, 1);
}
if (ret != ssl_hs_ok) {
return ret;
}
}
return ssl_hs_ok;
}
const char *tls13_client_handshake_state(SSL_HANDSHAKE *hs) {
enum client_hs_state_t state =
static_cast<enum client_hs_state_t>(hs->tls13_state);
switch (state) {
case state_read_hello_retry_request:
return "TLS 1.3 client read_hello_retry_request";
case state_send_second_client_hello:
return "TLS 1.3 client send_second_client_hello";
case state_read_server_hello:
return "TLS 1.3 client read_server_hello";
case state_read_encrypted_extensions:
return "TLS 1.3 client read_encrypted_extensions";
case state_read_certificate_request:
return "TLS 1.3 client read_certificate_request";
case state_read_server_certificate:
return "TLS 1.3 client read_server_certificate";
case state_read_server_certificate_verify:
return "TLS 1.3 client read_server_certificate_verify";
case state_server_certificate_reverify:
return "TLS 1.3 client server_certificate_reverify";
case state_read_server_finished:
return "TLS 1.3 client read_server_finished";
case state_send_end_of_early_data:
return "TLS 1.3 client send_end_of_early_data";
case state_send_client_encrypted_extensions:
return "TLS 1.3 client send_client_encrypted_extensions";
case state_send_client_certificate:
return "TLS 1.3 client send_client_certificate";
case state_send_client_certificate_verify:
return "TLS 1.3 client send_client_certificate_verify";
case state_complete_second_flight:
return "TLS 1.3 client complete_second_flight";
case state_done:
return "TLS 1.3 client done";
}
return "TLS 1.3 client unknown";
}
bool tls13_process_new_session_ticket(SSL *ssl, const SSLMessage &msg) {
if (ssl->s3->write_shutdown != ssl_shutdown_none) {
// Ignore tickets on shutdown. Callers tend to indiscriminately call
// |SSL_shutdown| before destroying an |SSL|, at which point calling the new
// session callback may be confusing.
return true;
}
CBS body = msg.body;
UniquePtr<SSL_SESSION> session = tls13_create_session_with_ticket(ssl, &body);
if (!session) {
return false;
}
if ((ssl->session_ctx->session_cache_mode & SSL_SESS_CACHE_CLIENT) &&
ssl->session_ctx->new_session_cb != NULL &&
ssl->session_ctx->new_session_cb(ssl, session.get())) {
// |new_session_cb|'s return value signals that it took ownership.
session.release();
}
return true;
}
UniquePtr<SSL_SESSION> tls13_create_session_with_ticket(SSL *ssl, CBS *body) {
UniquePtr<SSL_SESSION> session = SSL_SESSION_dup(
ssl->s3->established_session.get(), SSL_SESSION_INCLUDE_NONAUTH);
if (!session) {
return nullptr;
}
ssl_session_rebase_time(ssl, session.get());
uint32_t server_timeout;
CBS ticket_nonce, ticket, extensions;
if (!CBS_get_u32(body, &server_timeout) ||
!CBS_get_u32(body, &session->ticket_age_add) ||
!CBS_get_u8_length_prefixed(body, &ticket_nonce) ||
!CBS_get_u16_length_prefixed(body, &ticket) ||
CBS_len(&ticket) == 0 || //
!session->ticket.CopyFrom(ticket) ||
!CBS_get_u16_length_prefixed(body, &extensions) || //
CBS_len(body) != 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return nullptr;
}
// Cap the renewable lifetime by the server advertised value. This avoids
// wasting bandwidth on 0-RTT when we know the server will reject it.
if (session->timeout > server_timeout) {
session->timeout = server_timeout;
}
if (!tls13_derive_session_psk(session.get(), ticket_nonce,
SSL_is_dtls(ssl))) {
return nullptr;
}
SSLExtension early_data(TLSEXT_TYPE_early_data);
SSLExtension flags(TLSEXT_TYPE_tls_flags);
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_parse_extensions(&extensions, &alert, {&early_data, &flags},
/*ignore_unknown=*/true)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return nullptr;
}
if (early_data.present) {
if (!CBS_get_u32(&early_data.data, &session->ticket_max_early_data) ||
CBS_len(&early_data.data) != 0) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return nullptr;
}
// QUIC does not use the max_early_data_size parameter and always sets it to
// a fixed value. See RFC 9001, section 4.6.1.
if (SSL_is_quic(ssl) && session->ticket_max_early_data != 0xffffffff) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
return nullptr;
}
}
if (flags.present) {
SSLFlags parsed;
if (!ssl_parse_flags_extension_request(&flags.data, &parsed, &alert)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return nullptr;
}
if (parsed & kSSLFlagResumptionAcrossNames) {
session->is_resumable_across_names = true;
}
}
// Historically, OpenSSL filled in fake session IDs for ticket-based sessions.
// Envoy's tests depend on this, although perhaps they shouldn't.
session->session_id.ResizeForOverwrite(SHA256_DIGEST_LENGTH);
SHA256(CBS_data(&ticket), CBS_len(&ticket), session->session_id.data());
session->ticket_age_add_valid = true;
session->not_resumable = false;
return session;
}
BSSL_NAMESPACE_END