/* 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 "internal.h" enum server_hs_state_t { state_process_client_hello = 0, state_select_parameters, state_send_hello_retry_request, state_flush_hello_retry_request, state_process_second_client_hello, state_send_server_hello, state_send_encrypted_extensions, state_send_certificate_request, state_send_server_certificate, state_send_server_certificate_verify, state_complete_server_certificate_verify, state_send_server_finished, state_flush, state_process_client_certificate, state_process_client_certificate_verify, state_process_client_finished, state_send_new_session_ticket, state_flush_new_session_ticket, state_done, }; static const uint8_t kZeroes[EVP_MAX_MD_SIZE] = {0}; static int resolve_psk_secret(SSL *ssl) { SSL_HANDSHAKE *hs = ssl->s3->hs; if (ssl->s3->tmp.new_cipher->algorithm_auth != SSL_aPSK) { return tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len); } uint8_t resumption_psk[EVP_MAX_MD_SIZE]; if (!tls13_resumption_psk(ssl, resumption_psk, hs->hash_len, ssl->s3->new_session) || !tls13_advance_key_schedule(ssl, resumption_psk, hs->hash_len)) { return 0; } return 1; } static int resolve_ecdhe_secret(SSL *ssl, int *out_need_retry, struct ssl_early_callback_ctx *early_ctx) { *out_need_retry = 0; SSL_HANDSHAKE *hs = ssl->s3->hs; if (ssl->s3->tmp.new_cipher->algorithm_mkey != SSL_kECDHE) { return tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len); } CBS key_share; if (!ssl_early_callback_get_extension(early_ctx, &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 ssl_hs_error; } int found_key_share; uint8_t *dhe_secret; size_t dhe_secret_len; uint8_t alert; if (!ssl_ext_key_share_parse_clienthello(ssl, &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(ssl, dhe_secret, dhe_secret_len); OPENSSL_free(dhe_secret); return ok; } static enum ssl_hs_wait_t do_process_client_hello(SSL *ssl, SSL_HANDSHAKE *hs) { if (!tls13_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) { return ssl_hs_error; } struct ssl_early_callback_ctx client_hello; if (!ssl_early_callback_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; } assert(ssl->s3->have_version); /* Load the client random. */ if (client_hello.random_len != SSL3_RANDOM_SIZE) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return -1; } memcpy(ssl->s3->client_random, client_hello.random, client_hello.random_len); uint8_t alert = SSL_AD_DECODE_ERROR; SSL_SESSION *session = NULL; CBS pre_shared_key; if (ssl_early_callback_get_extension(&client_hello, &pre_shared_key, TLSEXT_TYPE_pre_shared_key) && !ssl_ext_pre_shared_key_parse_clienthello(ssl, &session, &alert, &pre_shared_key)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, alert); return 0; } uint16_t resumption_cipher; if (session != NULL && /* We currently only support ECDHE-PSK resumption. */ ((session->ticket_flags & SSL_TICKET_ALLOW_DHE_RESUMPTION) == 0 || /* Only resume if the session's version matches. */ session->ssl_version != ssl->version || !ssl_cipher_get_ecdhe_psk_cipher(session->cipher, &resumption_cipher) || !ssl_client_cipher_list_contains_cipher(&client_hello, resumption_cipher))) { SSL_SESSION_free(session); session = NULL; } if (session == NULL) { if (!ssl_get_new_session(ssl, 1 /* server */)) { ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } } else { /* Only authentication information carries over in TLS 1.3. */ ssl->s3->new_session = SSL_SESSION_dup(session, SSL_SESSION_DUP_AUTH_ONLY); if (ssl->s3->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); } 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; } /* TLS 1.3 requires the peer only advertise the null compression. */ if (client_hello.compression_methods_len != 1 || client_hello.compression_methods[0] != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_COMPRESSION_LIST); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return ssl_hs_error; } /* TLS extensions. */ if (!ssl_parse_clienthello_tlsext(ssl, &client_hello)) { OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT); return ssl_hs_error; } hs->state = state_select_parameters; return ssl_hs_ok; } static enum ssl_hs_wait_t do_select_parameters(SSL *ssl, SSL_HANDSHAKE *hs) { if (!ssl->s3->session_reused) { /* Call |cert_cb| to update server certificates if required. */ if (ssl->cert->cert_cb != NULL) { int rv = ssl->cert->cert_cb(ssl, ssl->cert->cert_cb_arg); if (rv == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } if (rv < 0) { hs->state = state_select_parameters; return ssl_hs_x509_lookup; } } } struct ssl_early_callback_ctx client_hello; if (!ssl_early_callback_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; } if (!ssl->s3->session_reused) { const SSL_CIPHER *cipher = ssl3_choose_cipher(ssl, &client_hello, ssl_get_cipher_preferences(ssl)); if (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; } ssl->s3->new_session->cipher = cipher; ssl->s3->tmp.new_cipher = cipher; } else { uint16_t resumption_cipher; if (!ssl_cipher_get_ecdhe_psk_cipher(ssl->s3->new_session->cipher, &resumption_cipher)) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER); ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } ssl->s3->tmp.new_cipher = SSL_get_cipher_by_value(resumption_cipher); } ssl->method->received_flight(ssl); /* The PRF hash is now known. Set up the key schedule and hash the * ClientHello. */ size_t resumption_ctx_len = EVP_MD_size(ssl_get_handshake_digest(ssl_get_algorithm_prf(ssl))); if (ssl->s3->session_reused) { uint8_t resumption_ctx[EVP_MAX_MD_SIZE]; if (!tls13_resumption_context(ssl, resumption_ctx, resumption_ctx_len, ssl->s3->new_session) || !tls13_init_key_schedule(ssl, resumption_ctx, resumption_ctx_len)) { return ssl_hs_error; } } else { if (!tls13_init_key_schedule(ssl, kZeroes, resumption_ctx_len)) { return ssl_hs_error; } } /* Resolve PSK and incorporate it into the secret. */ if (!resolve_psk_secret(ssl)) { return ssl_hs_error; } /* Resolve ECDHE and incorporate it into the secret. */ int need_retry; if (!resolve_ecdhe_secret(ssl, &need_retry, &client_hello)) { if (need_retry) { hs->state = state_send_hello_retry_request; return ssl_hs_ok; } return ssl_hs_error; } hs->state = state_send_server_hello; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_hello_retry_request(SSL *ssl, SSL_HANDSHAKE *hs) { 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) || !CBB_add_u16(&body, ssl_cipher_get_value(ssl->s3->tmp.new_cipher)) || !tls1_get_shared_group(ssl, &group_id) || !CBB_add_u16(&body, group_id) || !CBB_add_u16_length_prefixed(&body, &extensions) || !ssl->method->finish_message(ssl, &cbb)) { CBB_cleanup(&cbb); return ssl_hs_error; } hs->state = state_flush_hello_retry_request; return ssl_hs_write_message; } static enum ssl_hs_wait_t do_flush_hello_retry_request(SSL *ssl, SSL_HANDSHAKE *hs) { hs->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 *ssl, SSL_HANDSHAKE *hs) { if (!tls13_check_message_type(ssl, SSL3_MT_CLIENT_HELLO)) { return ssl_hs_error; } struct ssl_early_callback_ctx client_hello; if (!ssl_early_callback_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(ssl, &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->method->hash_current_message(ssl)) { return ssl_hs_error; } ssl->method->received_flight(ssl); hs->state = state_send_server_hello; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_hello(SSL *ssl, SSL_HANDSHAKE *hs) { 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(ssl->s3->tmp.new_cipher)) || !CBB_add_u16_length_prefixed(&body, &extensions) || !ssl_ext_pre_shared_key_add_serverhello(ssl, &extensions) || !ssl_ext_key_share_add_serverhello(ssl, &extensions) || !ssl->method->finish_message(ssl, &cbb)) { CBB_cleanup(&cbb); return ssl_hs_error; } hs->state = state_send_encrypted_extensions; return ssl_hs_write_message; } static enum ssl_hs_wait_t do_send_encrypted_extensions(SSL *ssl, SSL_HANDSHAKE *hs) { if (!tls13_set_handshake_traffic(ssl)) { return ssl_hs_error; } CBB cbb, body; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_ENCRYPTED_EXTENSIONS) || !ssl_add_serverhello_tlsext(ssl, &body) || !ssl->method->finish_message(ssl, &cbb)) { CBB_cleanup(&cbb); return ssl_hs_error; } hs->state = state_send_certificate_request; return ssl_hs_write_message; } static enum ssl_hs_wait_t do_send_certificate_request(SSL *ssl, SSL_HANDSHAKE *hs) { /* Determine whether to request a client certificate. */ ssl->s3->tmp.cert_request = !!(ssl->verify_mode & SSL_VERIFY_PEER); /* CertificateRequest may only be sent in certificate-based ciphers. */ if (!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) { ssl->s3->tmp.cert_request = 0; } if (!ssl->s3->tmp.cert_request) { /* Skip this state. */ hs->state = state_send_server_certificate; return ssl_hs_ok; } CBB cbb, body, 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_psigalgs(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->method->finish_message(ssl, &cbb)) { goto err; } hs->state = state_send_server_certificate; return ssl_hs_write_message; err: CBB_cleanup(&cbb); return ssl_hs_error; } static enum ssl_hs_wait_t do_send_server_certificate(SSL *ssl, SSL_HANDSHAKE *hs) { if (!ssl_cipher_uses_certificate_auth(ssl->s3->tmp.new_cipher)) { hs->state = state_send_server_finished; return ssl_hs_ok; } if (!ssl_has_certificate(ssl)) { OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_SET); return ssl_hs_error; } if (!tls13_prepare_certificate(ssl)) { return ssl_hs_error; } hs->state = state_send_server_certificate_verify; return ssl_hs_write_message; } static enum ssl_hs_wait_t do_send_server_certificate_verify(SSL *ssl, SSL_HANDSHAKE *hs, int is_first_run) { switch (tls13_prepare_certificate_verify(ssl, is_first_run)) { case ssl_private_key_success: hs->state = state_send_server_finished; return ssl_hs_write_message; case ssl_private_key_retry: hs->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 *ssl, SSL_HANDSHAKE *hs) { if (!tls13_prepare_finished(ssl)) { return ssl_hs_error; } hs->state = state_flush; return ssl_hs_write_message; } static enum ssl_hs_wait_t do_flush(SSL *ssl, SSL_HANDSHAKE *hs) { /* Update the secret to the master secret and derive traffic keys. */ if (!tls13_advance_key_schedule(ssl, kZeroes, hs->hash_len) || !tls13_derive_traffic_secret_0(ssl) || !tls13_set_traffic_key(ssl, type_data, evp_aead_seal, hs->traffic_secret_0, hs->hash_len)) { return ssl_hs_error; } hs->state = state_process_client_certificate; return ssl_hs_flush_and_read_message; } static enum ssl_hs_wait_t do_process_client_certificate(SSL *ssl, SSL_HANDSHAKE *hs) { if (!ssl->s3->tmp.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. */ ssl->s3->new_session->verify_result = X509_V_OK; /* Skip this state. */ hs->state = state_process_client_finished; return ssl_hs_ok; } const int allow_anonymous = (ssl->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) == 0; if (!tls13_check_message_type(ssl, SSL3_MT_CERTIFICATE) || !tls13_process_certificate(ssl, allow_anonymous) || !ssl->method->hash_current_message(ssl)) { return ssl_hs_error; } /* For historical reasons, the server's copy of the chain does not include the * leaf while the client's does. */ if (sk_X509_num(ssl->s3->new_session->cert_chain) > 0) { X509_free(sk_X509_shift(ssl->s3->new_session->cert_chain)); } hs->state = state_process_client_certificate_verify; return ssl_hs_read_message; } static enum ssl_hs_wait_t do_process_client_certificate_verify( SSL *ssl, SSL_HANDSHAKE *hs) { if (ssl->s3->new_session->peer == NULL) { /* Skip this state. */ hs->state = state_process_client_finished; return ssl_hs_ok; } if (!tls13_check_message_type(ssl, SSL3_MT_CERTIFICATE_VERIFY) || !tls13_process_certificate_verify(ssl) || !ssl->method->hash_current_message(ssl)) { return 0; } hs->state = state_process_client_finished; return ssl_hs_read_message; } static enum ssl_hs_wait_t do_process_client_finished(SSL *ssl, SSL_HANDSHAKE *hs) { if (!tls13_check_message_type(ssl, SSL3_MT_FINISHED) || !tls13_process_finished(ssl) || !ssl->method->hash_current_message(ssl) || /* evp_aead_seal keys have already been switched. */ !tls13_set_traffic_key(ssl, type_data, evp_aead_open, hs->traffic_secret_0, hs->hash_len) || !tls13_finalize_keys(ssl)) { return ssl_hs_error; } ssl->method->received_flight(ssl); hs->state = state_send_new_session_ticket; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_new_session_ticket(SSL *ssl, SSL_HANDSHAKE *hs) { SSL_SESSION *session = ssl->s3->new_session; session->tlsext_tick_lifetime_hint = session->timeout; session->ticket_flags = SSL_TICKET_ALLOW_DHE_RESUMPTION; if (!RAND_bytes((uint8_t *)&session->ticket_age_add, sizeof(session->ticket_age_add))) { return 0; } session->ticket_age_add_valid = 1; CBB cbb, body, ticket; if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_NEW_SESSION_TICKET) || !CBB_add_u32(&body, session->tlsext_tick_lifetime_hint) || !CBB_add_u32(&body, session->ticket_flags) || !CBB_add_u32(&body, session->ticket_age_add) || !CBB_add_u16(&body, 0 /* no ticket extensions */) || !CBB_add_u16_length_prefixed(&body, &ticket) || !ssl_encrypt_ticket(ssl, &ticket, session) || !ssl->method->finish_message(ssl, &cbb)) { CBB_cleanup(&cbb); return ssl_hs_error; } hs->session_tickets_sent++; hs->state = state_flush_new_session_ticket; return ssl_hs_write_message; } /* 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; static enum ssl_hs_wait_t do_flush_new_session_ticket(SSL *ssl, SSL_HANDSHAKE *hs) { if (hs->session_tickets_sent >= kNumTickets) { hs->state = state_done; } else { hs->state = state_send_new_session_ticket; } return ssl_hs_flush; } enum ssl_hs_wait_t tls13_server_handshake(SSL *ssl) { SSL_HANDSHAKE *hs = ssl->s3->hs; while (hs->state != state_done) { enum ssl_hs_wait_t ret = ssl_hs_error; enum server_hs_state_t state = hs->state; switch (state) { case state_process_client_hello: ret = do_process_client_hello(ssl, hs); break; case state_select_parameters: ret = do_select_parameters(ssl, hs); break; case state_send_hello_retry_request: ret = do_send_hello_retry_request(ssl, hs); break; case state_flush_hello_retry_request: ret = do_flush_hello_retry_request(ssl, hs); break; case state_process_second_client_hello: ret = do_process_second_client_hello(ssl, hs); break; case state_send_server_hello: ret = do_send_server_hello(ssl, hs); break; case state_send_encrypted_extensions: ret = do_send_encrypted_extensions(ssl, hs); break; case state_send_certificate_request: ret = do_send_certificate_request(ssl, hs); break; case state_send_server_certificate: ret = do_send_server_certificate(ssl, hs); break; case state_send_server_certificate_verify: ret = do_send_server_certificate_verify(ssl, hs, 1 /* first run */); break; case state_complete_server_certificate_verify: ret = do_send_server_certificate_verify(ssl, hs, 0 /* complete */); break; case state_send_server_finished: ret = do_send_server_finished(ssl, hs); break; case state_flush: ret = do_flush(ssl, hs); break; case state_process_client_certificate: ret = do_process_client_certificate(ssl, hs); break; case state_process_client_certificate_verify: ret = do_process_client_certificate_verify(ssl, hs); break; case state_process_client_finished: ret = do_process_client_finished(ssl, hs); break; case state_send_new_session_ticket: ret = do_send_new_session_ticket(ssl, hs); break; case state_flush_new_session_ticket: ret = do_flush_new_session_ticket(ssl, hs); break; case state_done: ret = ssl_hs_ok; break; } if (ret != ssl_hs_ok) { return ret; } } return ssl_hs_ok; }