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tls13_server.cc
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// 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 <string.h>
#include <algorithm>
#include <tuple>
#include <openssl/aead.h>
#include <openssl/bytestring.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/hpke.h>
#include <openssl/mem.h>
#include <openssl/rand.h>
#include <openssl/stack.h>
#include "../crypto/internal.h"
#include "internal.h"
BSSL_NAMESPACE_BEGIN
static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0};
// Allow a minute of ticket age skew in either direction. This covers
// transmission delays in ClientHello and NewSessionTicket, as well as
// drift between client and server clock rate since the ticket was issued.
// See RFC 8446, section 8.3.
static const int32_t kMaxTicketAgeSkewSeconds = 60;
static bool resolve_pake_secret(SSL_HANDSHAKE *hs) {
uint8_t verifier_share[spake2plus::kShareSize];
uint8_t verifier_confirm[spake2plus::kConfirmSize];
uint8_t shared_secret[spake2plus::kSecretSize];
if (!hs->pake_verifier->ProcessProverShare(verifier_share, verifier_confirm,
shared_secret,
hs->pake_share->pake_message)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(hs->ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return false;
}
bssl::ScopedCBB cbb;
if (!CBB_init(cbb.get(), sizeof(verifier_share) + sizeof(verifier_confirm)) ||
!CBB_add_bytes(cbb.get(), verifier_share, sizeof(verifier_share)) ||
!CBB_add_bytes(cbb.get(), verifier_confirm, sizeof(verifier_confirm)) ||
!CBBFinishArray(cbb.get(), &hs->pake_share_bytes)) {
return false;
}
return tls13_advance_key_schedule(
hs, MakeConstSpan(shared_secret, sizeof(shared_secret)));
}
static bool resolve_ecdhe_secret(SSL_HANDSHAKE *hs,
const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
const uint16_t group_id = hs->new_session->group_id;
bool found_key_share;
Span<const uint8_t> peer_key;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_ext_key_share_parse_clienthello(hs, &found_key_share, &peer_key,
&alert, client_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return false;
}
if (!found_key_share) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
return false;
}
Array<uint8_t> secret;
SSL_HANDSHAKE_HINTS *const hints = hs->hints.get();
if (hints && !hs->hints_requested && hints->key_share_group_id == group_id &&
!hints->key_share_secret.empty()) {
// Copy the key_share secret from hints.
if (!hs->key_share_ciphertext.CopyFrom(hints->key_share_ciphertext) ||
!secret.CopyFrom(hints->key_share_secret)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return false;
}
} else {
ScopedCBB ciphertext;
UniquePtr<SSLKeyShare> key_share = SSLKeyShare::Create(group_id);
if (!key_share || //
!CBB_init(ciphertext.get(), 32) ||
!key_share->Encap(ciphertext.get(), &secret, &alert, peer_key) ||
!CBBFinishArray(ciphertext.get(), &hs->key_share_ciphertext)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return false;
}
if (hints && hs->hints_requested) {
hints->key_share_group_id = group_id;
if (!hints->key_share_ciphertext.CopyFrom(hs->key_share_ciphertext) ||
!hints->key_share_secret.CopyFrom(secret)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return false;
}
}
}
return tls13_advance_key_schedule(hs, secret);
}
static int ssl_ext_supported_versions_add_serverhello(SSL_HANDSHAKE *hs,
CBB *out) {
CBB contents;
if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) || //
!CBB_add_u16_length_prefixed(out, &contents) || //
!CBB_add_u16(&contents, hs->ssl->s3->version) || //
!CBB_flush(out)) {
return 0;
}
return 1;
}
static const SSL_CIPHER *choose_tls13_cipher(
const SSL *ssl, const SSL_CLIENT_HELLO *client_hello) {
CBS cipher_suites;
CBS_init(&cipher_suites, client_hello->cipher_suites,
client_hello->cipher_suites_len);
const uint16_t version = ssl_protocol_version(ssl);
return ssl_choose_tls13_cipher(cipher_suites,
ssl->config->aes_hw_override
? ssl->config->aes_hw_override_value
: EVP_has_aes_hardware(),
version, ssl->config->compliance_policy);
}
static bool add_new_session_tickets(SSL_HANDSHAKE *hs, bool *out_sent_tickets) {
SSL *const ssl = hs->ssl;
if ( // If the client doesn't accept resumption with PSK_DHE_KE, don't send a
// session ticket.
!hs->accept_psk_mode ||
// We only implement stateless resumption in TLS 1.3, so skip sending
// tickets if disabled.
(SSL_get_options(ssl) & SSL_OP_NO_TICKET) ||
// Don't send tickets for PAKE connections. We don't support resumption
// with PAKEs.
hs->pake_verifier != nullptr) {
*out_sent_tickets = false;
return true;
}
// Rebase the session timestamp so that it is measured from ticket
// issuance.
ssl_session_rebase_time(ssl, hs->new_session.get());
assert(ssl->session_ctx->num_tickets <= kMaxTickets);
bool sent_tickets = false;
for (size_t i = 0; i < ssl->session_ctx->num_tickets; i++) {
UniquePtr<SSL_SESSION> session(
SSL_SESSION_dup(hs->new_session.get(), SSL_SESSION_INCLUDE_NONAUTH));
if (!session) {
return false;
}
if (!RAND_bytes((uint8_t *)&session->ticket_age_add, 4)) {
return false;
}
session->ticket_age_add_valid = true;
// TODO(crbug.com/381113363): Remove the SSL_is_dtls check once we support
// 0-RTT for DTLS 1.3.
bool enable_early_data =
ssl->enable_early_data &&
(!SSL_is_quic(ssl) || !ssl->config->quic_early_data_context.empty()) &&
!SSL_is_dtls(ssl);
if (enable_early_data) {
// 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.
session->ticket_max_early_data =
SSL_is_quic(ssl) ? 0xffffffff : kMaxEarlyDataAccepted;
}
static_assert(kMaxTickets < 256, "Too many tickets");
assert(i < 256);
uint8_t nonce[] = {static_cast<uint8_t>(i)};
ScopedCBB cbb;
CBB body, nonce_cbb, ticket, extensions;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_NEW_SESSION_TICKET) ||
!CBB_add_u32(&body, session->timeout) ||
!CBB_add_u32(&body, session->ticket_age_add) ||
!CBB_add_u8_length_prefixed(&body, &nonce_cbb) ||
!CBB_add_bytes(&nonce_cbb, nonce, sizeof(nonce)) ||
!tls13_derive_session_psk(session.get(), nonce, SSL_is_dtls(ssl)) ||
!CBB_add_u16_length_prefixed(&body, &ticket) ||
!ssl_encrypt_ticket(hs, &ticket, session.get())) {
return false;
}
if (CBB_len(&ticket) == 0) {
// The caller decided not to encrypt a ticket. Skip the message.
continue;
}
if (!CBB_add_u16_length_prefixed(&body, &extensions)) {
return false;
}
if (enable_early_data) {
CBB early_data;
if (!CBB_add_u16(&extensions, TLSEXT_TYPE_early_data) ||
!CBB_add_u16_length_prefixed(&extensions, &early_data) ||
!CBB_add_u32(&early_data, session->ticket_max_early_data) ||
!CBB_flush(&extensions)) {
return false;
}
}
// Add a fake extension. See RFC 8701.
if (!CBB_add_u16(&extensions,
ssl_get_grease_value(hs, ssl_grease_ticket_extension)) ||
!CBB_add_u16(&extensions, 0 /* empty */)) {
return false;
}
if (!ssl_add_message_cbb(ssl, cbb.get())) {
return false;
}
sent_tickets = true;
}
*out_sent_tickets = sent_tickets;
return true;
}
static bool check_signature_credential(SSL_HANDSHAKE *hs,
const SSL_CREDENTIAL *cred,
uint16_t *out_sigalg) {
switch (cred->type) {
case SSLCredentialType::kX509:
break;
case SSLCredentialType::kDelegated:
// Check that the peer supports the signature over the delegated
// credential.
if (std::find(hs->peer_sigalgs.begin(), hs->peer_sigalgs.end(),
cred->dc_algorithm) == hs->peer_sigalgs.end()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
return false;
}
break;
default:
OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CERTIFICATE_TYPE);
return false;
}
// If we reach here then the credential requires a signature. If |cred| is a
// delegated credential, this also checks that the peer supports delegated
// credentials and matched |dc_cert_verify_algorithm|.
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 bool check_pake_credential(SSL_HANDSHAKE *hs,
const SSL_CREDENTIAL *cred) {
assert(cred->type == SSLCredentialType::kSPAKE2PlusV1Server);
// Look for a client PAKE share that matches |cred|.
if (hs->pake_share == nullptr ||
hs->pake_share->named_pake != SSL_PAKE_SPAKE2PLUSV1 ||
hs->pake_share->client_identity != Span(cred->client_identity) ||
hs->pake_share->server_identity != Span(cred->server_identity)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_PAKE_MISMATCH);
return false;
}
return true;
}
static enum ssl_hs_wait_t do_select_parameters(SSL_HANDSHAKE *hs) {
// At this point, most ClientHello extensions have already been processed by
// the common handshake logic. Resolve the remaining non-PSK parameters.
SSL *const ssl = hs->ssl;
SSLMessage msg;
SSL_CLIENT_HELLO client_hello;
if (!hs->GetClientHello(&msg, &client_hello)) {
return ssl_hs_error;
}
if (SSL_is_quic(ssl) && client_hello.session_id_len > 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_COMPATIBILITY_MODE);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// DTLS 1.3 disables compatibility mode, and even if the client advertised a
// session ID (for resumption in DTLS 1.2), the server "MUST NOT echo the
// 'legacy_session_id' value from the client" (RFC 9147, section 5) as it
// would in a TLS 1.3 handshake.
if (!SSL_is_dtls(ssl)) {
hs->session_id.CopyFrom(
Span(client_hello.session_id, client_hello.session_id_len));
}
Array<SSL_CREDENTIAL *> creds;
if (!ssl_get_full_credential_list(hs, &creds)) {
return ssl_hs_error;
}
if (creds.empty()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
// Select the credential to use.
for (SSL_CREDENTIAL *cred : creds) {
ERR_clear_error();
if (cred->type == SSLCredentialType::kSPAKE2PlusV1Server) {
if (check_pake_credential(hs, cred)) {
hs->credential = UpRef(cred);
hs->pake_verifier = MakeUnique<spake2plus::Verifier>();
if (hs->pake_verifier == nullptr ||
!hs->pake_verifier->Init(cred->pake_context, cred->client_identity,
cred->server_identity,
cred->password_verifier_w0,
cred->registration_record)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
break;
}
} else {
uint16_t sigalg;
if (check_signature_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;
}
// Negotiate the cipher suite.
hs->new_cipher = choose_tls13_cipher(ssl, &client_hello);
if (hs->new_cipher == NULL) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
// HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was
// deferred. Complete it now.
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// The PRF hash is now known.
if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher)) {
return ssl_hs_error;
}
hs->tls13_state = state13_select_session;
return ssl_hs_ok;
}
static enum ssl_ticket_aead_result_t select_session(
SSL_HANDSHAKE *hs, uint8_t *out_alert, UniquePtr<SSL_SESSION> *out_session,
int32_t *out_ticket_age_skew, bool *out_offered_ticket,
const SSLMessage &msg, const SSL_CLIENT_HELLO *client_hello) {
SSL *const ssl = hs->ssl;
*out_session = nullptr;
CBS pre_shared_key;
*out_offered_ticket = ssl_client_hello_get_extension(
client_hello, &pre_shared_key, TLSEXT_TYPE_pre_shared_key);
if (!*out_offered_ticket) {
return ssl_ticket_aead_ignore_ticket;
}
// Per RFC 8446, section 4.2.9, servers MUST abort the handshake if the client
// sends pre_shared_key without psk_key_exchange_modes.
CBS unused;
if (!ssl_client_hello_get_extension(client_hello, &unused,
TLSEXT_TYPE_psk_key_exchange_modes)) {
*out_alert = SSL_AD_MISSING_EXTENSION;
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
return ssl_ticket_aead_error;
}
CBS ticket, binders;
uint32_t client_ticket_age;
if (!ssl_ext_pre_shared_key_parse_clienthello(
hs, &ticket, &binders, &client_ticket_age, out_alert, client_hello,
&pre_shared_key)) {
return ssl_ticket_aead_error;
}
// If the peer did not offer psk_dhe, ignore the resumption.
if (!hs->accept_psk_mode) {
return ssl_ticket_aead_ignore_ticket;
}
// We do not currently support resumption with PAKEs.
if (hs->credential != nullptr &&
hs->credential->type == SSLCredentialType::kSPAKE2PlusV1Server) {
return ssl_ticket_aead_ignore_ticket;
}
// TLS 1.3 session tickets are renewed separately as part of the
// NewSessionTicket.
bool unused_renew;
UniquePtr<SSL_SESSION> session;
enum ssl_ticket_aead_result_t ret =
ssl_process_ticket(hs, &session, &unused_renew, ticket, {});
switch (ret) {
case ssl_ticket_aead_success:
break;
case ssl_ticket_aead_error:
*out_alert = SSL_AD_INTERNAL_ERROR;
return ret;
default:
return ret;
}
if (!ssl_session_is_resumable(hs, session.get()) ||
// Historically, some TLS 1.3 tickets were missing ticket_age_add.
!session->ticket_age_add_valid) {
return ssl_ticket_aead_ignore_ticket;
}
// Recover the client ticket age and convert to seconds.
client_ticket_age -= session->ticket_age_add;
client_ticket_age /= 1000;
OPENSSL_timeval now = ssl_ctx_get_current_time(ssl->ctx.get());
// Compute the server ticket age in seconds.
assert(now.tv_sec >= session->time);
uint64_t server_ticket_age = now.tv_sec - session->time;
// To avoid overflowing |hs->ticket_age_skew|, we will not resume
// 68-year-old sessions.
if (server_ticket_age > INT32_MAX) {
return ssl_ticket_aead_ignore_ticket;
}
*out_ticket_age_skew = static_cast<int32_t>(client_ticket_age) -
static_cast<int32_t>(server_ticket_age);
// Check the PSK binder.
if (!tls13_verify_psk_binder(hs, session.get(), msg, &binders)) {
*out_alert = SSL_AD_DECRYPT_ERROR;
return ssl_ticket_aead_error;
}
*out_session = std::move(session);
return ssl_ticket_aead_success;
}
static bool quic_ticket_compatible(const SSL_SESSION *session,
const SSL_CONFIG *config) {
if (!session->is_quic) {
return true;
}
if (session->quic_early_data_context.empty() ||
config->quic_early_data_context.size() !=
session->quic_early_data_context.size() ||
CRYPTO_memcmp(config->quic_early_data_context.data(),
session->quic_early_data_context.data(),
session->quic_early_data_context.size()) != 0) {
return false;
}
return true;
}
static enum ssl_hs_wait_t do_select_session(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
SSLMessage msg;
SSL_CLIENT_HELLO client_hello;
if (!hs->GetClientHello(&msg, &client_hello)) {
return ssl_hs_error;
}
uint8_t alert = SSL_AD_DECODE_ERROR;
UniquePtr<SSL_SESSION> session;
bool offered_ticket = false;
switch (select_session(hs, &alert, &session, &ssl->s3->ticket_age_skew,
&offered_ticket, msg, &client_hello)) {
case ssl_ticket_aead_ignore_ticket:
assert(!session);
if (!ssl_get_new_session(hs)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
break;
case ssl_ticket_aead_success:
// Carry over authentication information from the previous handshake into
// a fresh session.
hs->new_session =
SSL_SESSION_dup(session.get(), SSL_SESSION_DUP_AUTH_ONLY);
if (hs->new_session == nullptr) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
ssl->s3->session_reused = true;
hs->can_release_private_key = true;
// 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);
break;
case ssl_ticket_aead_error:
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
case ssl_ticket_aead_retry:
hs->tls13_state = state13_select_session;
return ssl_hs_pending_ticket;
}
// Negotiate ALPS now, after ALPN is negotiated and |hs->new_session| is
// initialized.
if (!ssl_negotiate_alps(hs, &alert, &client_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// Record connection properties in the new session.
hs->new_session->cipher = hs->new_cipher;
// If using key shares, resolve the supported group and determine if we need
// HelloRetryRequest.
bool need_hrr = false;
if (hs->pake_verifier == nullptr) {
if (!tls1_get_shared_group(hs, &hs->new_session->group_id)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_GROUP);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
return ssl_hs_error;
}
bool found_key_share;
if (!ssl_ext_key_share_parse_clienthello(hs, &found_key_share,
/*out_key_share=*/nullptr, &alert,
&client_hello)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
need_hrr = !found_key_share;
}
// Determine if we're negotiating 0-RTT.
if (!ssl->enable_early_data) {
ssl->s3->early_data_reason = ssl_early_data_disabled;
} else if (!offered_ticket) {
ssl->s3->early_data_reason = ssl_early_data_no_session_offered;
} else if (!session) {
ssl->s3->early_data_reason = ssl_early_data_session_not_resumed;
} else if (session->ticket_max_early_data == 0) {
ssl->s3->early_data_reason = ssl_early_data_unsupported_for_session;
} else if (!hs->early_data_offered) {
ssl->s3->early_data_reason = ssl_early_data_peer_declined;
} else if (hs->channel_id_negotiated) {
// Channel ID is incompatible with 0-RTT.
ssl->s3->early_data_reason = ssl_early_data_channel_id;
} else if (Span(ssl->s3->alpn_selected) != session->early_alpn) {
// The negotiated ALPN must match the one in the ticket.
ssl->s3->early_data_reason = ssl_early_data_alpn_mismatch;
} else if (hs->new_session->has_application_settings !=
session->has_application_settings ||
Span(hs->new_session->local_application_settings) !=
session->local_application_settings) {
ssl->s3->early_data_reason = ssl_early_data_alps_mismatch;
} else if (ssl->s3->ticket_age_skew < -kMaxTicketAgeSkewSeconds ||
kMaxTicketAgeSkewSeconds < ssl->s3->ticket_age_skew) {
ssl->s3->early_data_reason = ssl_early_data_ticket_age_skew;
} else if (!quic_ticket_compatible(session.get(), hs->config)) {
ssl->s3->early_data_reason = ssl_early_data_quic_parameter_mismatch;
} else if (need_hrr) {
ssl->s3->early_data_reason = ssl_early_data_hello_retry_request;
} else {
// |ssl_session_is_resumable| forbids cross-cipher resumptions even if the
// PRF hashes match.
assert(hs->new_cipher == session->cipher);
ssl->s3->early_data_reason = ssl_early_data_accepted;
ssl->s3->early_data_accepted = true;
}
// Store the ALPN and ALPS values in the session for 0-RTT. Note the peer
// applications settings are not generally known until client
// EncryptedExtensions.
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;
}
// The peer applications settings are usually received later, in
// EncryptedExtensions. But, in 0-RTT handshakes, we carry over the
// values from |session|. Do this now, before |session| is discarded.
if (ssl->s3->early_data_accepted &&
hs->new_session->has_application_settings &&
!hs->new_session->peer_application_settings.CopyFrom(
session->peer_application_settings)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
// Copy the QUIC early data context to the session.
if (ssl->enable_early_data && SSL_is_quic(ssl)) {
if (!hs->new_session->quic_early_data_context.CopyFrom(
hs->config->quic_early_data_context)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
}
if (ssl->ctx->dos_protection_cb != NULL &&
ssl->ctx->dos_protection_cb(&client_hello) == 0) {
// Connection rejected for DOS reasons.
OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
size_t hash_len = EVP_MD_size(
ssl_get_handshake_digest(ssl_protocol_version(ssl), hs->new_cipher));
// Set up the key schedule and incorporate the PSK into the running secret.
if (!tls13_init_key_schedule(hs, ssl->s3->session_reused
? Span(hs->new_session->secret)
: Span(kZeroes, hash_len)) ||
!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
if (ssl->s3->early_data_accepted) {
if (!tls13_derive_early_secret(hs)) {
return ssl_hs_error;
}
} else if (hs->early_data_offered) {
ssl->s3->skip_early_data = true;
}
if (need_hrr) {
ssl->method->next_message(ssl);
if (!hs->transcript.UpdateForHelloRetryRequest()) {
return ssl_hs_error;
}
hs->tls13_state = state13_send_hello_retry_request;
return ssl_hs_ok;
}
if (hs->pake_verifier) {
assert(!ssl->s3->session_reused);
// Revealing the PAKE share (notably confirmV) allows the client to confirm
// one PAKE guess, so we must deduct from the brute force limit.
if (!hs->credential->ClaimPAKEAttempt()) {
OPENSSL_PUT_ERROR(SSL, SSL_R_PAKE_EXHAUSTED);
ssl_send_alert(hs->ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
return ssl_hs_error;
}
if (!resolve_pake_secret(hs)) {
return ssl_hs_error;
}
} else {
if (!resolve_ecdhe_secret(hs, &client_hello)) {
return ssl_hs_error;
}
}
ssl->method->next_message(ssl);
hs->ech_client_hello_buf.Reset();
hs->tls13_state = state13_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_hello_retry_request(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
if (hs->hints_requested) {
return ssl_hs_hints_ready;
}
// Although a server could HelloRetryRequest with PAKEs to request a cookie,
// we never do so.
assert(hs->pake_verifier == nullptr);
ScopedCBB cbb;
CBB body, session_id, extensions;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) ||
!CBB_add_u16(&body,
SSL_is_dtls(ssl) ? DTLS1_2_VERSION : TLS1_2_VERSION) ||
!CBB_add_bytes(&body, kHelloRetryRequest, SSL3_RANDOM_SIZE) ||
!CBB_add_u8_length_prefixed(&body, &session_id) ||
!CBB_add_bytes(&session_id, hs->session_id.data(),
hs->session_id.size()) ||
!CBB_add_u16(&body, SSL_CIPHER_get_protocol_id(hs->new_cipher)) ||
!CBB_add_u8(&body, 0 /* no compression */) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!CBB_add_u16(&extensions, TLSEXT_TYPE_supported_versions) ||
!CBB_add_u16(&extensions, 2 /* length */) ||
!CBB_add_u16(&extensions, ssl->s3->version) ||
!CBB_add_u16(&extensions, TLSEXT_TYPE_key_share) ||
!CBB_add_u16(&extensions, 2 /* length */) ||
!CBB_add_u16(&extensions, hs->new_session->group_id)) {
return ssl_hs_error;
}
if (hs->ech_is_inner) {
// Fill a placeholder for the ECH confirmation value.
if (!CBB_add_u16(&extensions, TLSEXT_TYPE_encrypted_client_hello) ||
!CBB_add_u16(&extensions, ECH_CONFIRMATION_SIGNAL_LEN) ||
!CBB_add_zeros(&extensions, ECH_CONFIRMATION_SIGNAL_LEN)) {
return ssl_hs_error;
}
}
Array<uint8_t> hrr;
if (!ssl->method->finish_message(ssl, cbb.get(), &hrr)) {
return ssl_hs_error;
}
if (hs->ech_is_inner) {
// Now that the message is encoded, fill in the whole value.
size_t offset = hrr.size() - ECH_CONFIRMATION_SIGNAL_LEN;
if (!ssl_ech_accept_confirmation(
hs, Span(hrr).last(ECH_CONFIRMATION_SIGNAL_LEN),
ssl->s3->client_random, hs->transcript, /*is_hrr=*/true, hrr,
offset)) {
return ssl_hs_error;
}
}
if (!ssl->method->add_message(ssl, std::move(hrr)) ||
!ssl->method->add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
ssl->s3->used_hello_retry_request = true;
hs->tls13_state = state13_read_second_client_hello;
return ssl_hs_flush;
}
static enum ssl_hs_wait_t do_read_second_client_hello(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_CLIENT_HELLO)) {
return ssl_hs_error;
}
SSL_CLIENT_HELLO client_hello;
if (!SSL_parse_client_hello(ssl, &client_hello, CBS_data(&msg.body),
CBS_len(&msg.body))) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
return ssl_hs_error;
}
if (ssl->s3->ech_status == ssl_ech_accepted) {
// If we previously accepted the ClientHelloInner, the second ClientHello
// must contain an outer encrypted_client_hello extension.
CBS ech_body;
if (!ssl_client_hello_get_extension(&client_hello, &ech_body,
TLSEXT_TYPE_encrypted_client_hello)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION);
return ssl_hs_error;
}
uint16_t kdf_id, aead_id;
uint8_t type, config_id;
CBS enc, payload;
if (!CBS_get_u8(&ech_body, &type) || //
type != ECH_CLIENT_OUTER || //
!CBS_get_u16(&ech_body, &kdf_id) || //
!CBS_get_u16(&ech_body, &aead_id) ||
!CBS_get_u8(&ech_body, &config_id) ||
!CBS_get_u16_length_prefixed(&ech_body, &enc) ||
!CBS_get_u16_length_prefixed(&ech_body, &payload) ||
CBS_len(&ech_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 (kdf_id != EVP_HPKE_KDF_id(EVP_HPKE_CTX_kdf(hs->ech_hpke_ctx.get())) ||
aead_id !=
EVP_HPKE_AEAD_id(EVP_HPKE_CTX_aead(hs->ech_hpke_ctx.get())) ||
config_id != hs->ech_config_id || CBS_len(&enc) > 0) {
OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
// Decrypt the payload with the HPKE context from the first ClientHello.
uint8_t alert = SSL_AD_DECODE_ERROR;
bool unused;
if (!ssl_client_hello_decrypt(hs, &alert, &unused,
&hs->ech_client_hello_buf, &client_hello,
payload)) {
// Decryption failure is fatal in the second ClientHello.
OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED);
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// Reparse |client_hello| from the buffer owned by |hs|.
if (!hs->GetClientHello(&msg, &client_hello)) {
OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
return ssl_hs_error;
}
}
// We perform all our negotiation based on the first ClientHello (for
// consistency with what |select_certificate_cb| observed), which is in the
// transcript, so we can ignore most of this second one.
//
// We do, however, check the second PSK binder. This covers the client key
// share, in case we ever send half-RTT data (we currently do not). It is also
// a tricky computation, so we enforce the peer handled it correctly.
if (ssl->s3->session_reused) {
CBS pre_shared_key;
if (!ssl_client_hello_get_extension(&client_hello, &pre_shared_key,
TLSEXT_TYPE_pre_shared_key)) {
OPENSSL_PUT_ERROR(SSL, SSL_R_INCONSISTENT_CLIENT_HELLO);
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
return ssl_hs_error;
}
CBS ticket, binders;
uint32_t client_ticket_age;
uint8_t alert = SSL_AD_DECODE_ERROR;
if (!ssl_ext_pre_shared_key_parse_clienthello(
hs, &ticket, &binders, &client_ticket_age, &alert, &client_hello,
&pre_shared_key)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
return ssl_hs_error;
}
// Note it is important that we do not obtain a new |SSL_SESSION| from
// |ticket|. We have already selected parameters based on the first
// ClientHello (in the transcript) and must not switch partway through.
if (!tls13_verify_psk_binder(hs, hs->new_session.get(), msg, &binders)) {
ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
return ssl_hs_error;
}
}
// Although a server could HelloRetryRequest with PAKEs to request a cookie,
// we never do so.
assert(hs->pake_verifier == nullptr);
if (!resolve_ecdhe_secret(hs, &client_hello)) {
return ssl_hs_error;
}
if (!ssl_hash_message(hs, msg)) {
return ssl_hs_error;
}
// ClientHello 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->ech_client_hello_buf.Reset();
hs->tls13_state = state13_send_server_hello;
return ssl_hs_ok;
}
static enum ssl_hs_wait_t do_send_server_hello(SSL_HANDSHAKE *hs) {
SSL *const ssl = hs->ssl;
Span<uint8_t> random(ssl->s3->server_random);
SSL_HANDSHAKE_HINTS *const hints = hs->hints.get();
if (hints && !hs->hints_requested &&
hints->server_random_tls13.size() == random.size()) {
OPENSSL_memcpy(random.data(), hints->server_random_tls13.data(),
random.size());
} else {
RAND_bytes(random.data(), random.size());
if (hints && hs->hints_requested &&
!hints->server_random_tls13.CopyFrom(random)) {
return ssl_hs_error;
}
}
Array<uint8_t> server_hello;
ScopedCBB cbb;
CBB body, extensions, session_id;
if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) ||
!CBB_add_u16(&body,
SSL_is_dtls(ssl) ? DTLS1_2_VERSION : TLS1_2_VERSION) ||
!CBB_add_bytes(&body, ssl->s3->server_random,
sizeof(ssl->s3->server_random)) ||
!CBB_add_u8_length_prefixed(&body, &session_id) ||
!CBB_add_bytes(&session_id, hs->session_id.data(),
hs->session_id.size()) ||
!CBB_add_u16(&body, SSL_CIPHER_get_protocol_id(hs->new_cipher)) ||
!CBB_add_u8(&body, 0) ||
!CBB_add_u16_length_prefixed(&body, &extensions) ||
!ssl_ext_pre_shared_key_add_serverhello(hs, &extensions) ||
!ssl_ext_pake_add_serverhello(hs, &extensions) ||
!ssl_ext_key_share_add_serverhello(hs, &extensions) ||
!ssl_ext_supported_versions_add_serverhello(hs, &extensions) ||
!ssl->method->finish_message(ssl, cbb.get(), &server_hello)) {
return ssl_hs_error;
}
assert(ssl->s3->ech_status != ssl_ech_accepted || hs->ech_is_inner);
if (hs->ech_is_inner) {
// Fill in the ECH confirmation signal.
const size_t offset = ssl_ech_confirmation_signal_hello_offset(ssl);
Span<uint8_t> random_suffix = random.last(ECH_CONFIRMATION_SIGNAL_LEN);
if (!ssl_ech_accept_confirmation(hs, random_suffix, ssl->s3->client_random,
hs->transcript,
/*is_hrr=*/false, server_hello, offset)) {
return ssl_hs_error;
}
// Update |server_hello|.
Span<uint8_t> server_hello_out =
Span(server_hello).subspan(offset, ECH_CONFIRMATION_SIGNAL_LEN);
OPENSSL_memcpy(server_hello_out.data(), random_suffix.data(),
ECH_CONFIRMATION_SIGNAL_LEN);
}
if (!ssl->method->add_message(ssl, std::move(server_hello))) {
return ssl_hs_error;
}
hs->key_share_ciphertext.Reset(); // No longer needed.
if (!ssl->s3->used_hello_retry_request &&
!ssl->method->add_change_cipher_spec(ssl)) {
return ssl_hs_error;
}
// Derive and enable the handshake traffic secrets.
if (!tls13_derive_handshake_secrets(hs) ||
!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_seal,
hs->new_session.get(),
hs->server_handshake_secret)) {
return ssl_hs_error;
}
// Send EncryptedExtensions.
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_ENCRYPTED_EXTENSIONS) ||
!ssl_add_serverhello_tlsext(hs, &body) ||
!ssl_add_message_cbb(ssl, cbb.get())) {
return ssl_hs_error;
}
if (!ssl->s3->session_reused && !hs->pake_verifier) {
// Determine whether to request a client certificate.
hs->cert_request = !!(hs->config->verify_mode & SSL_VERIFY_PEER);
// Only request a certificate if Channel ID isn't negotiated.
if ((hs->config->verify_mode & SSL_VERIFY_PEER_IF_NO_OBC) &&
hs->channel_id_negotiated) {
hs->cert_request = false;
}
}
// Send a CertificateRequest, if necessary.
if (hs->cert_request) {
CBB cert_request_extensions, sigalg_contents, sigalgs_cbb;
if (!ssl->method->init_message(ssl, cbb.get(), &body,
SSL3_MT_CERTIFICATE_REQUEST) ||
!CBB_add_u8(&body, 0 /* no certificate_request_context. */) ||
!CBB_add_u16_length_prefixed(&body, &cert_request_extensions) ||
!CBB_add_u16(&cert_request_extensions,
TLSEXT_TYPE_signature_algorithms) ||
!CBB_add_u16_length_prefixed(&cert_request_extensions,
&sigalg_contents) ||
!CBB_add_u16_length_prefixed(&sigalg_contents, &sigalgs_cbb) ||
!tls12_add_verify_sigalgs(hs, &sigalgs_cbb)) {
return ssl_hs_error;