/* Copyright (c) 2016, Google Inc. * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include #include #include #include #include #include #include #include #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 int resolve_ecdhe_secret(SSL_HANDSHAKE *hs, bool *out_need_retry, SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; *out_need_retry = false; // We only support connections that include an ECDHE key exchange. CBS key_share; if (!ssl_client_hello_get_extension(client_hello, &key_share, TLSEXT_TYPE_key_share)) { OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION); return 0; } bool found_key_share; Array dhe_secret; uint8_t alert = SSL_AD_DECODE_ERROR; if (!ssl_ext_key_share_parse_clienthello(hs, &found_key_share, &dhe_secret, &alert, &key_share)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return 0; } if (!found_key_share) { *out_need_retry = true; return 0; } return tls13_advance_key_schedule(hs, dhe_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->version) || !CBB_flush(out)) { return 0; } return 1; } static const SSL_CIPHER *choose_tls13_cipher( const SSL *ssl, const SSL_CLIENT_HELLO *client_hello, uint16_t group_id) { 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, version, group_id); } 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)) { *out_sent_tickets = false; return true; } // TLS 1.3 recommends single-use tickets, so issue multiple tickets in case // the client makes several connections before getting a renewal. static const int kNumTickets = 2; // Rebase the session timestamp so that it is measured from ticket // issuance. ssl_session_rebase_time(ssl, hs->new_session.get()); for (int i = 0; i < kNumTickets; i++) { UniquePtr 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; bool enable_early_data = ssl->enable_early_data && (!ssl->quic_method || !ssl->config->quic_early_data_context.empty()); if (enable_early_data) { // QUIC does not use the max_early_data_size parameter and always sets it // to a fixed value. See draft-ietf-quic-tls-22, section 4.5. session->ticket_max_early_data = ssl->quic_method != nullptr ? 0xffffffff : kMaxEarlyDataAccepted; } static_assert(kNumTickets < 256, "Too many tickets"); uint8_t nonce[] = {static_cast(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)) || !CBB_add_u16_length_prefixed(&body, &ticket) || !tls13_derive_session_psk(session.get(), nonce) || !ssl_encrypt_ticket(hs, &ticket, session.get()) || !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 draft-davidben-tls-grease-01. 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; } } *out_sent_tickets = true; 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; if (!ssl->method->get_message(ssl, &msg)) { return ssl_hs_read_message; } SSL_CLIENT_HELLO client_hello; if (!ssl_client_hello_init(ssl, &client_hello, msg)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } if (ssl->quic_method != nullptr && 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; } OPENSSL_memcpy(hs->session_id, client_hello.session_id, client_hello.session_id_len); hs->session_id_len = client_hello.session_id_len; uint16_t group_id; if (!tls1_get_shared_group(hs, &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; } // Negotiate the cipher suite. hs->new_cipher = choose_tls13_cipher(ssl, &client_hello, group_id); 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. Set up the key schedule and hash the // ClientHello. 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 *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 RFC8446, 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; } // TLS 1.3 session tickets are renewed separately as part of the // NewSessionTicket. bool unused_renew; UniquePtr 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; struct OPENSSL_timeval now; ssl_get_current_time(ssl, &now); // 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(client_ticket_age) - static_cast(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; if (!ssl->method->get_message(ssl, &msg)) { return ssl_hs_read_message; } SSL_CLIENT_HELLO client_hello; if (!ssl_client_hello_init(ssl, &client_hello, msg)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } uint8_t alert = SSL_AD_DECODE_ERROR; UniquePtr 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, 1 /* server */)) { 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; // 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; } // 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 (ssl->s3->channel_id_valid) { // Channel ID is incompatible with 0-RTT. ssl->s3->early_data_reason = ssl_early_data_channel_id; } else if (ssl->s3->token_binding_negotiated) { // Token Binding is incompatible with 0-RTT. ssl->s3->early_data_reason = ssl_early_data_token_binding; } else if (MakeConstSpan(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 || MakeConstSpan(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 { // |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; } // Record connection properties in the new session. hs->new_session->cipher = hs->new_cipher; // 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->quic_method) { 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 (ssl->s3->session_reused) { if (!tls13_init_key_schedule( hs, MakeConstSpan(hs->new_session->secret, hs->new_session->secret_length))) { return ssl_hs_error; } } else if (!tls13_init_key_schedule(hs, MakeConstSpan(kZeroes, hash_len))) { return ssl_hs_error; } if (!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; } // Resolve ECDHE and incorporate it into the secret. bool need_retry; if (!resolve_ecdhe_secret(hs, &need_retry, &client_hello)) { if (need_retry) { if (ssl->s3->early_data_accepted) { ssl->s3->early_data_reason = ssl_early_data_hello_retry_request; ssl->s3->early_data_accepted = false; } ssl->s3->skip_early_data = true; 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; } return ssl_hs_error; } ssl->method->next_message(ssl); 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; ScopedCBB cbb; CBB body, session_id, extensions; uint16_t group_id; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) || !CBB_add_u16(&body, 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, hs->session_id_len) || !CBB_add_u16(&body, SSL_CIPHER_get_protocol_id(hs->new_cipher)) || !CBB_add_u8(&body, 0 /* no compression */) || !tls1_get_shared_group(hs, &group_id) || !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->version) || !CBB_add_u16(&extensions, TLSEXT_TYPE_key_share) || !CBB_add_u16(&extensions, 2 /* length */) || !CBB_add_u16(&extensions, group_id) || !ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } if (!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_client_hello_init(ssl, &client_hello, msg)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_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; } } bool need_retry; if (!resolve_ecdhe_secret(hs, &need_retry, &client_hello)) { if (need_retry) { // Only send one HelloRetryRequest. 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_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->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 random(ssl->s3->server_random); RAND_bytes(random.data(), random.size()); // If the ClientHello has an ech_is_inner extension, we must be the ECH // backend server. In response to ech_is_inner, we will overwrite part of the // ServerHello.random with the ECH acceptance confirmation. if (hs->ech_is_inner_present) { // Construct the ServerHelloECHConf message, which is the same as // ServerHello, except the last 8 bytes of its random field are zeroed out. Span random_suffix = random.subspan(24); OPENSSL_memset(random_suffix.data(), 0, random_suffix.size()); ScopedCBB cbb; CBB body, extensions, session_id; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) || !CBB_add_u16(&body, TLS1_2_VERSION) || !CBB_add_bytes(&body, random.data(), random.size()) || !CBB_add_u8_length_prefixed(&body, &session_id) || !CBB_add_bytes(&session_id, hs->session_id, hs->session_id_len) || !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_key_share_add_serverhello(hs, &extensions, /*dry_run=*/true) || !ssl_ext_supported_versions_add_serverhello(hs, &extensions) || !CBB_flush(cbb.get())) { return ssl_hs_error; } // Note that |cbb| includes the message type and length fields, but not the // record layer header. if (!tls13_ech_accept_confirmation( hs, random_suffix, bssl::MakeConstSpan(CBB_data(cbb.get()), CBB_len(cbb.get())))) { return ssl_hs_error; } } // Send a ServerHello. ScopedCBB cbb; CBB body, extensions, session_id; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) || !CBB_add_u16(&body, TLS1_2_VERSION) || !CBB_add_bytes(&body, random.data(), random.size()) || !CBB_add_u8_length_prefixed(&body, &session_id) || !CBB_add_bytes(&session_id, hs->session_id, hs->session_id_len) || !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_key_share_add_serverhello(hs, &extensions, /*dry_run=*/false) || !ssl_ext_supported_versions_add_serverhello(hs, &extensions) || !ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } 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) { // 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) && ssl->s3->channel_id_valid) { 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; } if (ssl_has_client_CAs(hs->config)) { CBB ca_contents; if (!CBB_add_u16(&cert_request_extensions, TLSEXT_TYPE_certificate_authorities) || !CBB_add_u16_length_prefixed(&cert_request_extensions, &ca_contents) || !ssl_add_client_CA_list(hs, &ca_contents) || !CBB_flush(&cert_request_extensions)) { return ssl_hs_error; } } if (!ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } } // Send the server Certificate message, if necessary. if (!ssl->s3->session_reused) { if (!ssl_has_certificate(hs)) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET); return ssl_hs_error; } if (!tls13_add_certificate(hs)) { return ssl_hs_error; } hs->tls13_state = state13_send_server_certificate_verify; return ssl_hs_ok; } hs->tls13_state = state13_send_server_finished; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_certificate_verify(SSL_HANDSHAKE *hs) { switch (tls13_add_certificate_verify(hs)) { case ssl_private_key_success: hs->tls13_state = state13_send_server_finished; return ssl_hs_ok; case ssl_private_key_retry: hs->tls13_state = state13_send_server_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_send_server_finished(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!tls13_add_finished(hs) || // Update the secret to the master secret and derive traffic keys. !tls13_advance_key_schedule( hs, MakeConstSpan(kZeroes, hs->transcript.DigestLen())) || !tls13_derive_application_secrets(hs) || !tls13_set_traffic_key(ssl, ssl_encryption_application, evp_aead_seal, hs->new_session.get(), hs->server_traffic_secret_0())) { return ssl_hs_error; } hs->tls13_state = state13_send_half_rtt_ticket; return hs->handback ? ssl_hs_handback : ssl_hs_ok; } static enum ssl_hs_wait_t do_send_half_rtt_ticket(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (ssl->s3->early_data_accepted) { // If accepting 0-RTT, we send tickets half-RTT. This gets the tickets on // the wire sooner and also avoids triggering a write on |SSL_read| when // processing the client Finished. This requires computing the client // Finished early. See RFC 8446, section 4.6.1. static const uint8_t kEndOfEarlyData[4] = {SSL3_MT_END_OF_EARLY_DATA, 0, 0, 0}; if (ssl->quic_method == nullptr && !hs->transcript.Update(kEndOfEarlyData)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } size_t finished_len; if (!tls13_finished_mac(hs, hs->expected_client_finished().data(), &finished_len, false /* client */)) { return ssl_hs_error; } if (finished_len != hs->expected_client_finished().size()) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } // Feed the predicted Finished into the transcript. This allows us to derive // the resumption secret early and send half-RTT tickets. // // TODO(davidben): This will need to be updated for DTLS 1.3. assert(!SSL_is_dtls(hs->ssl)); assert(hs->expected_client_finished().size() <= 0xff); uint8_t header[4] = { SSL3_MT_FINISHED, 0, 0, static_cast(hs->expected_client_finished().size())}; bool unused_sent_tickets; if (!hs->transcript.Update(header) || !hs->transcript.Update(hs->expected_client_finished()) || !tls13_derive_resumption_secret(hs) || !add_new_session_tickets(hs, &unused_sent_tickets)) { return ssl_hs_error; } } hs->tls13_state = state13_read_second_client_flight; return ssl_hs_flush; } static enum ssl_hs_wait_t do_read_second_client_flight(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (ssl->s3->early_data_accepted) { if (!tls13_set_traffic_key(ssl, ssl_encryption_early_data, evp_aead_open, hs->new_session.get(), hs->early_traffic_secret())) { return ssl_hs_error; } hs->can_early_write = true; hs->can_early_read = true; hs->in_early_data = true; } // QUIC doesn't use an EndOfEarlyData message (draft-ietf-quic-tls-22, // section 8.3), so we switch to client_handshake_secret before the early // return. if (ssl->quic_method != nullptr) { if (!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_open, hs->new_session.get(), hs->client_handshake_secret())) { return ssl_hs_error; } hs->tls13_state = state13_process_end_of_early_data; return ssl->s3->early_data_accepted ? ssl_hs_early_return : ssl_hs_ok; } hs->tls13_state = state13_process_end_of_early_data; return ssl->s3->early_data_accepted ? ssl_hs_read_end_of_early_data : ssl_hs_ok; } static enum ssl_hs_wait_t do_process_end_of_early_data(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; // In protocols that use EndOfEarlyData, we must consume the extra message and // switch to client_handshake_secret after the early return. if (ssl->quic_method == nullptr) { // If early data was not accepted, the EndOfEarlyData will be in the // discarded early data. if (hs->ssl->s3->early_data_accepted) { SSLMessage msg; if (!ssl->method->get_message(ssl, &msg)) { return ssl_hs_read_message; } if (!ssl_check_message_type(ssl, msg, SSL3_MT_END_OF_EARLY_DATA)) { return ssl_hs_error; } if (CBS_len(&msg.body) != 0) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); return ssl_hs_error; } ssl->method->next_message(ssl); } if (!tls13_set_traffic_key(ssl, ssl_encryption_handshake, evp_aead_open, hs->new_session.get(), hs->client_handshake_secret())) { return ssl_hs_error; } } hs->tls13_state = state13_read_client_encrypted_extensions; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_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) { 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; } // Parse out the extensions. bool have_application_settings = false; CBS application_settings; SSL_EXTENSION_TYPE ext_types[] = {{TLSEXT_TYPE_application_settings, &have_application_settings, &application_settings}}; uint8_t alert = SSL_AD_DECODE_ERROR; if (!ssl_parse_extensions(&extensions, &alert, ext_types, /*ignore_unknown=*/false)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } if (!have_application_settings) { OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION); return ssl_hs_error; } // Note that, if 0-RTT was accepted, these values will already have been // initialized earlier. if (!hs->new_session->peer_application_settings.CopyFrom( application_settings) || !ssl_hash_message(hs, msg)) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } ssl->method->next_message(ssl); } hs->tls13_state = state13_read_client_certificate; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_client_certificate(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!hs->cert_request) { if (!ssl->s3->session_reused) { // OpenSSL returns X509_V_OK when no certificates are requested. This is // classed by them as a bug, but it's assumed by at least NGINX. (Only do // this in full handshakes as resumptions should carry over the previous // |verify_result|, though this is a no-op because servers do not // implement the client's odd soft-fail mode.) hs->new_session->verify_result = X509_V_OK; } // Skip this state. hs->tls13_state = state13_read_channel_id; return ssl_hs_ok; } const bool allow_anonymous = (hs->config->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) == 0; SSLMessage msg; if (!ssl->method->get_message(ssl, &msg)) { return ssl_hs_read_message; } if (!ssl_check_message_type(ssl, msg, SSL3_MT_CERTIFICATE) || !tls13_process_certificate(hs, msg, allow_anonymous) || !ssl_hash_message(hs, msg)) { return ssl_hs_error; } ssl->method->next_message(ssl); hs->tls13_state = state13_read_client_certificate_verify; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_client_certificate_verify(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (sk_CRYPTO_BUFFER_num(hs->new_session->certs.get()) == 0) { // Skip this state. hs->tls13_state = state13_read_channel_id; return ssl_hs_ok; } 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 = state13_read_client_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 = state13_read_channel_id; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_channel_id(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!ssl->s3->channel_id_valid) { hs->tls13_state = state13_read_client_finished; 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_CHANNEL_ID) || !tls1_verify_channel_id(hs, msg) || !ssl_hash_message(hs, msg)) { return ssl_hs_error; } ssl->method->next_message(ssl); hs->tls13_state = state13_read_client_finished; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_client_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) || // If early data was accepted, we've already computed the client Finished // and derived the resumption secret. !tls13_process_finished(hs, msg, ssl->s3->early_data_accepted) || // evp_aead_seal keys have already been switched. !tls13_set_traffic_key(ssl, ssl_encryption_application, evp_aead_open, hs->new_session.get(), hs->client_traffic_secret_0())) { return ssl_hs_error; } if (!ssl->s3->early_data_accepted) { if (!ssl_hash_message(hs, msg) || !tls13_derive_resumption_secret(hs)) { return ssl_hs_error; } // We send post-handshake tickets as part of the handshake in 1-RTT. hs->tls13_state = state13_send_new_session_ticket; } else { // We already sent half-RTT tickets. hs->tls13_state = state13_done; } ssl->method->next_message(ssl); return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_new_session_ticket(SSL_HANDSHAKE *hs) { bool sent_tickets; if (!add_new_session_tickets(hs, &sent_tickets)) { return ssl_hs_error; } hs->tls13_state = state13_done; // In TLS 1.3, the NewSessionTicket isn't flushed until the server performs a // write, to prevent a non-reading client from causing the server to hang in // the case of a small server write buffer. Consumers which don't write data // to the client will need to do a zero-byte write if they wish to flush the // tickets. if (hs->ssl->quic_method != nullptr && sent_tickets) { return ssl_hs_flush; } return ssl_hs_ok; } enum ssl_hs_wait_t tls13_server_handshake(SSL_HANDSHAKE *hs) { while (hs->tls13_state != state13_done) { enum ssl_hs_wait_t ret = ssl_hs_error; enum tls13_server_hs_state_t state = static_cast(hs->tls13_state); switch (state) { case state13_select_parameters: ret = do_select_parameters(hs); break; case state13_select_session: ret = do_select_session(hs); break; case state13_send_hello_retry_request: ret = do_send_hello_retry_request(hs); break; case state13_read_second_client_hello: ret = do_read_second_client_hello(hs); break; case state13_send_server_hello: ret = do_send_server_hello(hs); break; case state13_send_server_certificate_verify: ret = do_send_server_certificate_verify(hs); break; case state13_send_server_finished: ret = do_send_server_finished(hs); break; case state13_send_half_rtt_ticket: ret = do_send_half_rtt_ticket(hs); break; case state13_read_second_client_flight: ret = do_read_second_client_flight(hs); break; case state13_process_end_of_early_data: ret = do_process_end_of_early_data(hs); break; case state13_read_client_encrypted_extensions: ret = do_read_client_encrypted_extensions(hs); break; case state13_read_client_certificate: ret = do_read_client_certificate(hs); break; case state13_read_client_certificate_verify: ret = do_read_client_certificate_verify(hs); break; case state13_read_channel_id: ret = do_read_channel_id(hs); break; case state13_read_client_finished: ret = do_read_client_finished(hs); break; case state13_send_new_session_ticket: ret = do_send_new_session_ticket(hs); break; case state13_done: ret = ssl_hs_ok; break; } if (hs->tls13_state != state) { ssl_do_info_callback(hs->ssl, SSL_CB_ACCEPT_LOOP, 1); } if (ret != ssl_hs_ok) { return ret; } } return ssl_hs_ok; } const char *tls13_server_handshake_state(SSL_HANDSHAKE *hs) { enum tls13_server_hs_state_t state = static_cast(hs->tls13_state); switch (state) { case state13_select_parameters: return "TLS 1.3 server select_parameters"; case state13_select_session: return "TLS 1.3 server select_session"; case state13_send_hello_retry_request: return "TLS 1.3 server send_hello_retry_request"; case state13_read_second_client_hello: return "TLS 1.3 server read_second_client_hello"; case state13_send_server_hello: return "TLS 1.3 server send_server_hello"; case state13_send_server_certificate_verify: return "TLS 1.3 server send_server_certificate_verify"; case state13_send_half_rtt_ticket: return "TLS 1.3 server send_half_rtt_ticket"; case state13_send_server_finished: return "TLS 1.3 server send_server_finished"; case state13_read_second_client_flight: return "TLS 1.3 server read_second_client_flight"; case state13_process_end_of_early_data: return "TLS 1.3 server process_end_of_early_data"; case state13_read_client_encrypted_extensions: return "TLS 1.3 server read_client_encrypted_extensions"; case state13_read_client_certificate: return "TLS 1.3 server read_client_certificate"; case state13_read_client_certificate_verify: return "TLS 1.3 server read_client_certificate_verify"; case state13_read_channel_id: return "TLS 1.3 server read_channel_id"; case state13_read_client_finished: return "TLS 1.3 server read_client_finished"; case state13_send_new_session_ticket: return "TLS 1.3 server send_new_session_ticket"; case state13_done: return "TLS 1.3 server done"; } return "TLS 1.3 server unknown"; } BSSL_NAMESPACE_END