/* 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. */ // Per C99, various stdint.h macros are unavailable in C++ unless some macros // are defined. C++11 overruled this decision, but older Android NDKs still // require it. #if !defined(__STDC_LIMIT_MACROS) #define __STDC_LIMIT_MACROS #endif #include #include #include #include #include #include #include #include #include #include #include "../crypto/internal.h" #include "internal.h" namespace bssl { enum server_hs_state_t { state_select_parameters = 0, state_select_session, state_send_hello_retry_request, state_read_second_client_hello, state_send_server_hello, state_send_server_certificate_verify, state_send_server_finished, state_read_second_client_flight, state_process_end_of_early_data, state_read_client_certificate, state_read_client_certificate_verify, state_read_channel_id, state_read_client_finished, state_send_new_session_ticket, state_done, }; static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0}; 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.data(), dhe_secret.size()); } 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) { if (client_hello->cipher_suites_len % 2 != 0) { return NULL; } CBS cipher_suites; CBS_init(&cipher_suites, client_hello->cipher_suites, client_hello->cipher_suites_len); const int aes_is_fine = EVP_has_aes_hardware(); const uint16_t version = ssl_protocol_version(ssl); const SSL_CIPHER *best = NULL; while (CBS_len(&cipher_suites) > 0) { uint16_t cipher_suite; if (!CBS_get_u16(&cipher_suites, &cipher_suite)) { return NULL; } // Limit to TLS 1.3 ciphers we know about. const SSL_CIPHER *candidate = SSL_get_cipher_by_value(cipher_suite); if (candidate == NULL || SSL_CIPHER_get_min_version(candidate) > version || SSL_CIPHER_get_max_version(candidate) < version) { continue; } // TLS 1.3 removes legacy ciphers, so honor the client order, but prefer // ChaCha20 if we do not have AES hardware. if (aes_is_fine) { return candidate; } if (candidate->algorithm_enc == SSL_CHACHA20POLY1305) { return candidate; } if (best == NULL) { best = candidate; } } return best; } 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; if (ssl->enable_early_data) { session->ticket_max_early_data = 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 (ssl->enable_early_data) { CBB early_data_info; if (!CBB_add_u16(&extensions, TLSEXT_TYPE_early_data) || !CBB_add_u16_length_prefixed(&extensions, &early_data_info) || !CBB_add_u32(&early_data_info, 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; } OPENSSL_memcpy(hs->session_id, client_hello.session_id, client_hello.session_id_len); hs->session_id_len = client_hello.session_id_len; // 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. Set up the key schedule and hash the // ClientHello. if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher)) { return ssl_hs_error; } if (!ssl_hash_message(hs, msg)) { return ssl_hs_error; } hs->tls13_state = state_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, const SSLMessage &msg, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; *out_session = NULL; // Decode the ticket if we agreed on a PSK key exchange mode. CBS pre_shared_key; if (!hs->accept_psk_mode || !ssl_client_hello_get_extension(client_hello, &pre_shared_key, TLSEXT_TYPE_pre_shared_key)) { return ssl_ticket_aead_ignore_ticket; } // Verify that the pre_shared_key extension is the last extension in // ClientHello. if (CBS_data(&pre_shared_key) + CBS_len(&pre_shared_key) != client_hello->extensions + client_hello->extensions_len) { OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST); *out_alert = SSL_AD_ILLEGAL_PARAMETER; 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, &pre_shared_key)) { return ssl_ticket_aead_error; } // 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; } // TODO(davidben,svaldez): Measure this value to decide on tolerance. For // now, accept all values. https://crbug.com/boringssl/113. *out_ticket_age_skew = (int32_t)client_ticket_age - (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 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; switch (select_session(hs, &alert, &session, &ssl->s3->ticket_age_skew, 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 (ssl->enable_early_data && // Early data must be acceptable for this ticket. session->ticket_max_early_data != 0 && // The client must have offered early data. hs->early_data_offered && // Channel ID is incompatible with 0-RTT. !ssl->s3->channel_id_valid && // If Token Binding is negotiated, reject 0-RTT. !ssl->s3->token_binding_negotiated && // The negotiated ALPN must match the one in the ticket. MakeConstSpan(ssl->s3->alpn_selected) == session->early_alpn) { ssl->s3->early_data_accepted = true; } if (hs->new_session == NULL) { 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 = state_select_session; return ssl_hs_pending_ticket; } // Record connection properties in the new session. hs->new_session->cipher = hs->new_cipher; // Store the initial 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->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, hs->new_session->master_key, hs->new_session->master_key_length)) { return ssl_hs_error; } } else if (!tls13_init_key_schedule(hs, kZeroes, hash_len)) { return ssl_hs_error; } if (ssl->s3->early_data_accepted) { if (!tls13_derive_early_secrets(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) { 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 = state_send_hello_retry_request; return ssl_hs_ok; } return ssl_hs_error; } ssl->method->next_message(ssl); hs->tls13_state = state_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_value(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; } hs->sent_hello_retry_request = true; hs->tls13_state = state_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; } 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; } ssl->method->next_message(ssl); hs->tls13_state = state_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; // 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) || !RAND_bytes(ssl->s3->server_random, sizeof(ssl->s3->server_random)) || !CBB_add_bytes(&body, ssl->s3->server_random, 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_value(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) || !ssl_ext_supported_versions_add_serverhello(hs, &extensions) || !ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } if (!hs->sent_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, evp_aead_seal, hs->server_handshake_secret, hs->hash_len)) { 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(ssl, &sigalgs_cbb, false /* online signature */)) { return ssl_hs_error; } if (tls12_has_different_verify_sigalgs_for_certs(ssl)) { if (!CBB_add_u16(&cert_request_extensions, TLSEXT_TYPE_signature_algorithms_cert) || !CBB_add_u16_length_prefixed(&cert_request_extensions, &sigalg_contents) || !CBB_add_u16_length_prefixed(&sigalg_contents, &sigalgs_cbb) || !tls12_add_verify_sigalgs(ssl, &sigalgs_cbb, true /* certs */)) { 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->config)) { 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 = state_send_server_certificate_verify; return ssl_hs_ok; } hs->tls13_state = state_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 = state_send_server_finished; return ssl_hs_ok; case ssl_private_key_retry: hs->tls13_state = state_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, kZeroes, hs->hash_len) || !tls13_derive_application_secrets(hs) || !tls13_set_traffic_key(ssl, evp_aead_seal, hs->server_traffic_secret_0, hs->hash_len)) { return ssl_hs_error; } 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 (!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, &finished_len, 0 /* client */)) { return ssl_hs_error; } if (finished_len != hs->hash_len) { 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->hash_len <= 0xff); uint8_t header[4] = {SSL3_MT_FINISHED, 0, 0, static_cast(hs->hash_len)}; bool unused_sent_tickets; if (!hs->transcript.Update(header) || !hs->transcript.Update( MakeConstSpan(hs->expected_client_finished, hs->hash_len)) || !tls13_derive_resumption_secret(hs) || !add_new_session_tickets(hs, &unused_sent_tickets)) { return ssl_hs_error; } } hs->tls13_state = state_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, evp_aead_open, hs->early_traffic_secret, hs->hash_len)) { return ssl_hs_error; } hs->can_early_write = true; hs->can_early_read = true; hs->in_early_data = true; } hs->tls13_state = state_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; if (hs->early_data_offered) { // If early data was not accepted, the EndOfEarlyData and ChangeCipherSpec // message 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, evp_aead_open, hs->client_handshake_secret, hs->hash_len)) { return ssl_hs_error; } hs->tls13_state = ssl->s3->early_data_accepted ? state_read_client_finished : state_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) { // 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. hs->new_session->verify_result = X509_V_OK; // Skip this state. hs->tls13_state = state_read_channel_id; return ssl_hs_ok; } const int 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 = state_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 = state_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 = state_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 = state_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 = state_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 = state_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, evp_aead_open, hs->client_traffic_secret_0, hs->hash_len)) { 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 = state_send_new_session_ticket; } else { // We already sent half-RTT tickets. hs->tls13_state = state_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 = state_done; return sent_tickets ? ssl_hs_flush : ssl_hs_ok; } enum ssl_hs_wait_t tls13_server_handshake(SSL_HANDSHAKE *hs) { while (hs->tls13_state != state_done) { enum ssl_hs_wait_t ret = ssl_hs_error; enum server_hs_state_t state = static_cast(hs->tls13_state); switch (state) { case state_select_parameters: ret = do_select_parameters(hs); break; case state_select_session: ret = do_select_session(hs); break; case state_send_hello_retry_request: ret = do_send_hello_retry_request(hs); break; case state_read_second_client_hello: ret = do_read_second_client_hello(hs); break; case state_send_server_hello: ret = do_send_server_hello(hs); break; case state_send_server_certificate_verify: ret = do_send_server_certificate_verify(hs); break; case state_send_server_finished: ret = do_send_server_finished(hs); break; case state_read_second_client_flight: ret = do_read_second_client_flight(hs); break; case state_process_end_of_early_data: ret = do_process_end_of_early_data(hs); break; case state_read_client_certificate: ret = do_read_client_certificate(hs); break; case state_read_client_certificate_verify: ret = do_read_client_certificate_verify(hs); break; case state_read_channel_id: ret = do_read_channel_id(hs); break; case state_read_client_finished: ret = do_read_client_finished(hs); break; case state_send_new_session_ticket: ret = do_send_new_session_ticket(hs); break; case state_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 server_hs_state_t state = static_cast(hs->tls13_state); switch (state) { case state_select_parameters: return "TLS 1.3 server select_parameters"; case state_select_session: return "TLS 1.3 server select_session"; case state_send_hello_retry_request: return "TLS 1.3 server send_hello_retry_request"; case state_read_second_client_hello: return "TLS 1.3 server read_second_client_hello"; case state_send_server_hello: return "TLS 1.3 server send_server_hello"; case state_send_server_certificate_verify: return "TLS 1.3 server send_server_certificate_verify"; case state_send_server_finished: return "TLS 1.3 server send_server_finished"; case state_read_second_client_flight: return "TLS 1.3 server read_second_client_flight"; case state_process_end_of_early_data: return "TLS 1.3 server process_end_of_early_data"; case state_read_client_certificate: return "TLS 1.3 server read_client_certificate"; case state_read_client_certificate_verify: return "TLS 1.3 server read_client_certificate_verify"; case state_read_channel_id: return "TLS 1.3 server read_channel_id"; case state_read_client_finished: return "TLS 1.3 server read_client_finished"; case state_send_new_session_ticket: return "TLS 1.3 server send_new_session_ticket"; case state_done: return "TLS 1.3 server done"; } return "TLS 1.3 server unknown"; } } // namespace bssl