/* 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 "../crypto/internal.h" #include "internal.h" /* kMaxEarlyDataAccepted is the advertised number of plaintext bytes of early * data that will be accepted. This value should be slightly below * kMaxEarlyDataSkipped in tls_record.c, which is measured in ciphertext. */ static const size_t kMaxEarlyDataAccepted = 14336; enum server_hs_state_t { state_select_parameters = 0, state_send_hello_retry_request, state_process_second_client_hello, state_send_server_hello, state_send_server_certificate_verify, state_complete_server_certificate_verify, state_send_server_finished, state_process_client_certificate, state_process_client_certificate_verify, state_process_channel_id, state_process_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, int *out_need_retry, SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; *out_need_retry = 0; /* 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); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_MISSING_EXTENSION); return 0; } int found_key_share; uint8_t *dhe_secret; size_t dhe_secret_len; uint8_t alert = SSL_AD_DECODE_ERROR; if (!ssl_ext_key_share_parse_clienthello(hs, &found_key_share, &dhe_secret, &dhe_secret_len, &alert, &key_share)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); return 0; } if (!found_key_share) { *out_need_retry = 1; return 0; } int ok = tls13_advance_key_schedule(hs, dhe_secret, dhe_secret_len); OPENSSL_free(dhe_secret); return ok; } 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 = ssl3_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 enum ssl_hs_wait_t do_select_parameters(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; /* The short record header extension is incompatible with early data. */ if (ssl->s3->skip_early_data && ssl->s3->short_header) { OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION); return ssl_hs_error; } SSL_CLIENT_HELLO client_hello; if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg, ssl->init_num)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); 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); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } /* The PRF hash is now known. Set up the key schedule and hash the * ClientHello. */ if (!tls13_init_key_schedule(hs) || !ssl_hash_current_message(hs)) { return ssl_hs_error; } /* Decode the ticket if we agree on a PSK key exchange mode. */ uint8_t alert = SSL_AD_DECODE_ERROR; SSL_SESSION *session = NULL; CBS pre_shared_key, binders; if (hs->accept_psk_mode && ssl_client_hello_get_extension(&client_hello, &pre_shared_key, TLSEXT_TYPE_pre_shared_key)) { /* 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); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return ssl_hs_error; } if (!ssl_ext_pre_shared_key_parse_clienthello(hs, &session, &binders, &alert, &pre_shared_key)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } } if (session != NULL && !ssl_session_is_resumable(hs, session)) { SSL_SESSION_free(session); session = NULL; } /* Set up the new session, either using the original one as a template or * creating a fresh one. */ if (session == NULL) { if (!ssl_get_new_session(hs, 1 /* server */)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } hs->new_session->cipher = hs->new_cipher; /* On new sessions, stash the SNI value in the session. */ if (hs->hostname != NULL) { OPENSSL_free(hs->new_session->tlsext_hostname); hs->new_session->tlsext_hostname = BUF_strdup(hs->hostname); if (hs->new_session->tlsext_hostname == NULL) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } } } else { /* Check the PSK binder. */ if (!tls13_verify_psk_binder(hs, session, &binders)) { SSL_SESSION_free(session); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); return ssl_hs_error; } /* Only authentication information carries over in TLS 1.3. */ hs->new_session = SSL_SESSION_dup(session, SSL_SESSION_DUP_AUTH_ONLY); if (hs->new_session == NULL) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } ssl->s3->session_reused = 1; SSL_SESSION_free(session); /* Resumption incorporates fresh key material, so refresh the timeout. */ ssl_session_renew_timeout(ssl, hs->new_session, ssl->initial_ctx->session_psk_dhe_timeout); } 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); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } /* HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was * deferred. Complete it now. */ alert = SSL_AD_DECODE_ERROR; if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } /* Store the initial negotiated ALPN in the session. */ if (ssl->s3->alpn_selected != NULL) { hs->new_session->early_alpn = BUF_memdup(ssl->s3->alpn_selected, ssl->s3->alpn_selected_len); if (hs->new_session->early_alpn == NULL) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } hs->new_session->early_alpn_len = ssl->s3->alpn_selected_len; } /* Incorporate the PSK into the running secret. */ if (ssl->s3->session_reused) { if (!tls13_advance_key_schedule(hs, hs->new_session->master_key, hs->new_session->master_key_length)) { return ssl_hs_error; } } else if (!tls13_advance_key_schedule(hs, kZeroes, hs->hash_len)) { return ssl_hs_error; } ssl->method->received_flight(ssl); /* Resolve ECDHE and incorporate it into the secret. */ int need_retry; if (!resolve_ecdhe_secret(hs, &need_retry, &client_hello)) { if (need_retry) { hs->tls13_state = state_send_hello_retry_request; return ssl_hs_ok; } return ssl_hs_error; } 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; CBB cbb, body, extensions; uint16_t group_id; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_HELLO_RETRY_REQUEST) || !CBB_add_u16(&body, ssl->version) || !tls1_get_shared_group(hs, &group_id) || !CBB_add_u16_length_prefixed(&body, &extensions) || !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)) { CBB_cleanup(&cbb); return ssl_hs_error; } hs->tls13_state = state_process_second_client_hello; return ssl_hs_flush_and_read_message; } static enum ssl_hs_wait_t do_process_second_client_hello(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!ssl_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) { return ssl_hs_error; } SSL_CLIENT_HELLO client_hello; if (!ssl_client_hello_init(ssl, &client_hello, ssl->init_msg, ssl->init_num)) { OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_PARSE_FAILED); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } int need_retry; if (!resolve_ecdhe_secret(hs, &need_retry, &client_hello)) { if (need_retry) { /* Only send one HelloRetryRequest. */ ssl3_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_current_message(hs)) { return ssl_hs_error; } ssl->method->received_flight(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. */ CBB cbb, body, extensions; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_SERVER_HELLO) || !CBB_add_u16(&body, ssl->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_u16(&body, ssl_cipher_get_value(hs->new_cipher)) || !CBB_add_u16_length_prefixed(&body, &extensions) || !ssl_ext_pre_shared_key_add_serverhello(hs, &extensions) || !ssl_ext_key_share_add_serverhello(hs, &extensions)) { goto err; } if (ssl->s3->short_header) { if (!CBB_add_u16(&extensions, TLSEXT_TYPE_short_header) || !CBB_add_u16(&extensions, 0 /* empty extension */)) { goto err; } } if (!ssl_add_message_cbb(ssl, &cbb)) { goto err; } /* Derive and enable the handshake traffic secrets. */ if (!tls13_derive_handshake_secrets(hs) || !tls13_set_traffic_key(ssl, evp_aead_open, hs->client_handshake_secret, hs->hash_len) || !tls13_set_traffic_key(ssl, evp_aead_seal, hs->server_handshake_secret, hs->hash_len)) { goto err; } /* Send EncryptedExtensions. */ if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_ENCRYPTED_EXTENSIONS) || !ssl_add_serverhello_tlsext(hs, &body) || !ssl_add_message_cbb(ssl, &cbb)) { goto err; } /* Determine whether to request a client certificate. */ hs->cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER); /* CertificateRequest may only be sent in non-resumption handshakes. */ if (ssl->s3->session_reused) { hs->cert_request = 0; } /* Send a CertificateRequest, if necessary. */ if (hs->cert_request) { CBB sigalgs_cbb; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_CERTIFICATE_REQUEST) || !CBB_add_u8(&body, 0 /* no certificate_request_context. */)) { goto err; } const uint16_t *sigalgs; size_t num_sigalgs = tls12_get_verify_sigalgs(ssl, &sigalgs); if (!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb)) { goto err; } for (size_t i = 0; i < num_sigalgs; i++) { if (!CBB_add_u16(&sigalgs_cbb, sigalgs[i])) { goto err; } } if (!ssl_add_client_CA_list(ssl, &body) || !CBB_add_u16(&body, 0 /* empty certificate_extensions. */) || !ssl_add_message_cbb(ssl, &cbb)) { goto err; } } /* Send the server Certificate message, if necessary. */ if (!ssl->s3->session_reused) { if (!ssl_has_certificate(ssl)) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET); goto err; } if (!tls13_add_certificate(hs)) { goto err; } hs->tls13_state = state_send_server_certificate_verify; return ssl_hs_ok; } hs->tls13_state = state_send_server_finished; return ssl_hs_ok; err: CBB_cleanup(&cbb); return ssl_hs_error; } static enum ssl_hs_wait_t do_send_server_certificate_verify(SSL_HANDSHAKE *hs, int is_first_run) { switch (tls13_add_certificate_verify(hs, is_first_run)) { 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_complete_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; } hs->tls13_state = state_process_client_certificate; return ssl_hs_flush_and_read_message; } static enum ssl_hs_wait_t do_process_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_process_channel_id; return ssl_hs_ok; } const int allow_anonymous = (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) == 0; if (!ssl_check_message_type(ssl, SSL3_MT_CERTIFICATE) || !tls13_process_certificate(hs, allow_anonymous) || !ssl_hash_current_message(hs)) { return ssl_hs_error; } hs->tls13_state = state_process_client_certificate_verify; return ssl_hs_read_message; } static enum ssl_hs_wait_t do_process_client_certificate_verify( SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (sk_CRYPTO_BUFFER_num(hs->new_session->certs) == 0) { /* Skip this state. */ hs->tls13_state = state_process_channel_id; return ssl_hs_ok; } if (!ssl_check_message_type(ssl, SSL3_MT_CERTIFICATE_VERIFY) || !tls13_process_certificate_verify(hs) || !ssl_hash_current_message(hs)) { return ssl_hs_error; } hs->tls13_state = state_process_channel_id; return ssl_hs_read_message; } static enum ssl_hs_wait_t do_process_channel_id(SSL_HANDSHAKE *hs) { if (!hs->ssl->s3->tlsext_channel_id_valid) { hs->tls13_state = state_process_client_finished; return ssl_hs_ok; } if (!ssl_check_message_type(hs->ssl, SSL3_MT_CHANNEL_ID) || !tls1_verify_channel_id(hs) || !ssl_hash_current_message(hs)) { return ssl_hs_error; } hs->tls13_state = state_process_client_finished; return ssl_hs_read_message; } static enum ssl_hs_wait_t do_process_client_finished(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!ssl_check_message_type(ssl, SSL3_MT_FINISHED) || !tls13_process_finished(hs) || !ssl_hash_current_message(hs) || /* evp_aead_seal keys have already been switched. */ !tls13_set_traffic_key(ssl, evp_aead_open, hs->client_traffic_secret_0, hs->hash_len) || !tls13_derive_resumption_secret(hs)) { return ssl_hs_error; } ssl->method->received_flight(ssl); /* Rebase the session timestamp so that it is measured from ticket * issuance. */ ssl_session_rebase_time(ssl, hs->new_session); hs->tls13_state = state_send_new_session_ticket; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_new_session_ticket(SSL_HANDSHAKE *hs) { /* 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; SSL *const ssl = hs->ssl; /* If the client doesn't accept resumption with PSK_DHE_KE, don't send a * session ticket. */ if (!hs->accept_psk_mode) { hs->tls13_state = state_done; return ssl_hs_ok; } SSL_SESSION *session = hs->new_session; CBB cbb; CBB_zero(&cbb); for (int i = 0; i < kNumTickets; i++) { if (!RAND_bytes((uint8_t *)&session->ticket_age_add, 4)) { goto err; } CBB body, ticket, extensions; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_NEW_SESSION_TICKET) || !CBB_add_u32(&body, session->timeout) || !CBB_add_u32(&body, session->ticket_age_add) || !CBB_add_u16_length_prefixed(&body, &ticket) || !ssl_encrypt_ticket(ssl, &ticket, session) || !CBB_add_u16_length_prefixed(&body, &extensions)) { goto err; } if (ssl->ctx->enable_early_data) { session->ticket_max_early_data = kMaxEarlyDataAccepted; CBB early_data_info; if (!CBB_add_u16(&extensions, TLSEXT_TYPE_ticket_early_data_info) || !CBB_add_u16_length_prefixed(&extensions, &early_data_info) || !CBB_add_u32(&early_data_info, session->ticket_max_early_data) || !CBB_flush(&extensions)) { goto err; } } /* Add a fake extension. See draft-davidben-tls-grease-01. */ if (!CBB_add_u16(&extensions, ssl_get_grease_value(ssl, ssl_grease_ticket_extension)) || !CBB_add_u16(&extensions, 0 /* empty */)) { goto err; } if (!ssl_add_message_cbb(ssl, &cbb)) { goto err; } } hs->session_tickets_sent++; hs->tls13_state = state_done; return ssl_hs_flush; err: CBB_cleanup(&cbb); return ssl_hs_error; } 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 = hs->tls13_state; switch (state) { case state_select_parameters: ret = do_select_parameters(hs); break; case state_send_hello_retry_request: ret = do_send_hello_retry_request(hs); break; case state_process_second_client_hello: ret = do_process_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, 1 /* first run */); break; case state_complete_server_certificate_verify: ret = do_send_server_certificate_verify(hs, 0 /* complete */); break; case state_send_server_finished: ret = do_send_server_finished(hs); break; case state_process_client_certificate: ret = do_process_client_certificate(hs); break; case state_process_client_certificate_verify: ret = do_process_client_certificate_verify(hs); break; case state_process_channel_id: ret = do_process_channel_id(hs); break; case state_process_client_finished: ret = do_process_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 (ret != ssl_hs_ok) { return ret; } } return ssl_hs_ok; }