// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. // Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved. // Copyright 2005 Nokia. All rights reserved. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "../crypto/bytestring/internal.h" #include "../crypto/internal.h" #include "internal.h" BSSL_NAMESPACE_BEGIN bool ssl_client_cipher_list_contains_cipher( const SSL_CLIENT_HELLO *client_hello, uint16_t id) { CBS cipher_suites; CBS_init(&cipher_suites, client_hello->cipher_suites, client_hello->cipher_suites_len); while (CBS_len(&cipher_suites) > 0) { uint16_t got_id; if (!CBS_get_u16(&cipher_suites, &got_id)) { return false; } if (got_id == id) { return true; } } return false; } static bool negotiate_version(SSL_HANDSHAKE *hs, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; assert(ssl->s3->version == 0); CBS supported_versions, versions; if (ssl_client_hello_get_extension(client_hello, &supported_versions, TLSEXT_TYPE_supported_versions)) { if (!CBS_get_u8_length_prefixed(&supported_versions, &versions) || // CBS_len(&supported_versions) != 0 || // CBS_len(&versions) == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } } else { // Convert the ClientHello version to an equivalent supported_versions // extension. static const uint8_t kTLSVersions[] = { 0x03, 0x03, // TLS 1.2 0x03, 0x02, // TLS 1.1 0x03, 0x01, // TLS 1 }; static const uint8_t kDTLSVersions[] = { 0xfe, 0xfd, // DTLS 1.2 0xfe, 0xff, // DTLS 1.0 }; size_t versions_len = 0; if (SSL_is_dtls(ssl)) { if (client_hello->version <= DTLS1_2_VERSION) { versions_len = 4; } else if (client_hello->version <= DTLS1_VERSION) { versions_len = 2; } versions = Span(kDTLSVersions).last(versions_len); } else { if (client_hello->version >= TLS1_2_VERSION) { versions_len = 6; } else if (client_hello->version >= TLS1_1_VERSION) { versions_len = 4; } else if (client_hello->version >= TLS1_VERSION) { versions_len = 2; } versions = Span(kTLSVersions).last(versions_len); } } if (!ssl_negotiate_version(hs, out_alert, &ssl->s3->version, &versions)) { return false; } // Handle FALLBACK_SCSV. if (ssl_client_cipher_list_contains_cipher(client_hello, SSL_CIPHER_FALLBACK_SCSV) && ssl_protocol_version(ssl) < hs->max_version) { OPENSSL_PUT_ERROR(SSL, SSL_R_INAPPROPRIATE_FALLBACK); *out_alert = SSL3_AD_INAPPROPRIATE_FALLBACK; return false; } return true; } static UniquePtr ssl_parse_client_cipher_list( const SSL_CLIENT_HELLO *client_hello) { CBS cipher_suites; CBS_init(&cipher_suites, client_hello->cipher_suites, client_hello->cipher_suites_len); UniquePtr sk(sk_SSL_CIPHER_new_null()); if (!sk) { return nullptr; } while (CBS_len(&cipher_suites) > 0) { uint16_t cipher_suite; if (!CBS_get_u16(&cipher_suites, &cipher_suite)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_IN_RECEIVED_CIPHER_LIST); return nullptr; } const SSL_CIPHER *c = SSL_get_cipher_by_value(cipher_suite); if (c != nullptr && !sk_SSL_CIPHER_push(sk.get(), c)) { return nullptr; } } return sk; } static const SSL_CIPHER *choose_cipher(SSL_HANDSHAKE *hs, const STACK_OF(SSL_CIPHER) *client_pref, uint32_t mask_k, uint32_t mask_a) { SSL *const ssl = hs->ssl; const STACK_OF(SSL_CIPHER) *prio, *allow; // in_group_flags will either be NULL, or will point to an array of bytes // which indicate equal-preference groups in the |prio| stack. See the // comment about |in_group_flags| in the |SSLCipherPreferenceList| // struct. const bool *in_group_flags; // best_index contains the index of the best matching cipher suite found so // far, indexed into |allow|. If |best_index| is |SIZE_MAX|, no matching // cipher suite has been found yet. size_t best_index = SIZE_MAX; const SSLCipherPreferenceList *server_pref = hs->config->cipher_list ? hs->config->cipher_list.get() : ssl->ctx->cipher_list.get(); if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) { prio = server_pref->ciphers.get(); in_group_flags = server_pref->in_group_flags; allow = client_pref; } else { prio = client_pref; in_group_flags = nullptr; allow = server_pref->ciphers.get(); } for (size_t i = 0; i < sk_SSL_CIPHER_num(prio); i++) { const SSL_CIPHER *c = sk_SSL_CIPHER_value(prio, i); const bool in_group = in_group_flags != nullptr && in_group_flags[i]; size_t cipher_index; if ( // Check if the cipher is supported for the current version. SSL_CIPHER_get_min_version(c) <= ssl_protocol_version(ssl) && // ssl_protocol_version(ssl) <= SSL_CIPHER_get_max_version(c) && // // Check the cipher is supported for the server configuration. (c->algorithm_mkey & mask_k) && // (c->algorithm_auth & mask_a) && // // Check the cipher is in the |allow| list. sk_SSL_CIPHER_find(allow, &cipher_index, c)) { // Within a group, |allow|'s preference order applies. if (best_index == SIZE_MAX || best_index > cipher_index) { best_index = cipher_index; } } // We are about to leave a (possibly singleton) group, but we found a match // in it, so that's our answer. if (!in_group && best_index != SIZE_MAX) { return sk_SSL_CIPHER_value(allow, best_index); } } // The final cipher suite must end a group, so, if we found a match, we must // have returned early above. assert(best_index == SIZE_MAX); OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SHARED_CIPHER); return nullptr; } struct TLS12ServerParams { bool ok() const { return cipher != nullptr; } const SSL_CIPHER *cipher = nullptr; uint16_t signature_algorithm = 0; }; static TLS12ServerParams choose_params(SSL_HANDSHAKE *hs, const SSLCredential *cred, Span allowed_cert_types, const STACK_OF(SSL_CIPHER) *client_pref, bool has_ecdhe_group) { // Determine the usable cipher suites. uint32_t mask_k = 0, mask_a = 0; if (has_ecdhe_group) { mask_k |= SSL_kECDHE; } if (hs->config->psk_server_callback != nullptr) { mask_k |= SSL_kPSK; mask_a |= SSL_aPSK; } assert(!allowed_cert_types.empty()); uint16_t sigalg = 0; if (cred != nullptr && (cred->type == SSLCredentialType::kX509 || cred->type == SSLCredentialType::kRawPublicKey)) { if (std::find(allowed_cert_types.begin(), allowed_cert_types.end(), *ssl_credential_type_to_cert_type(cred->type)) == allowed_cert_types.end()) { OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_CERTIFICATE_TYPE); return TLS12ServerParams(); } bool sign_ok = tls1_choose_signature_algorithm(hs, cred, &sigalg); ERR_clear_error(); // ECDSA keys must additionally be checked against the peer's supported // curve list. int key_type = EVP_PKEY_id(cred->pubkey.get()); if (key_type == EVP_PKEY_EC) { uint16_t group_id; if (!ssl_nid_to_group_id(&group_id, EVP_PKEY_get_ec_curve_nid(cred->pubkey.get())) || std::find(hs->peer_supported_group_list.begin(), hs->peer_supported_group_list.end(), group_id) == hs->peer_supported_group_list.end()) { sign_ok = false; // If this would make us unable to pick any cipher, return an error. // This is not strictly necessary, but it gives us a more specific // error to help the caller diagnose issues. if (mask_a == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE); return TLS12ServerParams(); } } } mask_a |= ssl_cipher_auth_mask_for_key(cred->pubkey.get(), sign_ok); if (key_type == EVP_PKEY_RSA) { mask_k |= SSL_kRSA; } } TLS12ServerParams params; params.cipher = choose_cipher(hs, client_pref, mask_k, mask_a); if (params.cipher == nullptr || (cred != nullptr && !ssl_credential_matches_requested_issuers(hs, cred))) { return TLS12ServerParams(); } // Only report the selected signature algorithm if it will be used. if (ssl_cipher_requires_server_key_exchange(params.cipher) && ssl_cipher_uses_certificate_auth(params.cipher)) { params.signature_algorithm = sigalg; } return params; } static enum ssl_hs_wait_t do_start_accept(SSL_HANDSHAKE *hs) { ssl_do_info_callback(hs->ssl, SSL_CB_HANDSHAKE_START, 1); hs->state = state12_read_client_hello; return ssl_hs_ok; } // is_probably_jdk11_with_tls13 returns whether |client_hello| was probably sent // from a JDK 11 client with both TLS 1.3 and a prior version enabled. static bool is_probably_jdk11_with_tls13(const SSL_CLIENT_HELLO *client_hello) { // JDK 11 ClientHellos contain a number of unusual properties which should // limit false positives. // JDK 11 does not support ChaCha20-Poly1305. This is unusual: many modern // clients implement ChaCha20-Poly1305. if (ssl_client_cipher_list_contains_cipher( client_hello, SSL_CIPHER_CHACHA20_POLY1305_SHA256)) { return false; } // JDK 11 always sends extensions in a particular order. constexpr uint16_t kMaxFragmentLength = 0x0001; constexpr uint16_t kStatusRequestV2 = 0x0011; static constexpr struct { uint16_t id; bool required; } kJavaExtensions[] = { {TLSEXT_TYPE_server_name, false}, {kMaxFragmentLength, false}, {TLSEXT_TYPE_status_request, false}, {TLSEXT_TYPE_supported_groups, true}, {TLSEXT_TYPE_ec_point_formats, false}, {TLSEXT_TYPE_signature_algorithms, true}, // Java always sends signature_algorithms_cert. {TLSEXT_TYPE_signature_algorithms_cert, true}, {TLSEXT_TYPE_application_layer_protocol_negotiation, false}, {kStatusRequestV2, false}, {TLSEXT_TYPE_extended_master_secret, false}, {TLSEXT_TYPE_supported_versions, true}, {TLSEXT_TYPE_cookie, false}, {TLSEXT_TYPE_psk_key_exchange_modes, true}, {TLSEXT_TYPE_key_share, true}, {TLSEXT_TYPE_renegotiate, false}, {TLSEXT_TYPE_pre_shared_key, false}, }; Span sigalgs, sigalgs_cert; bool has_status_request = false, has_status_request_v2 = false; CBS extensions, supported_groups; CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len); for (const auto &java_extension : kJavaExtensions) { CBS copy = extensions; uint16_t id; if (CBS_get_u16(©, &id) && id == java_extension.id) { // The next extension is the one we expected. extensions = copy; CBS body; if (!CBS_get_u16_length_prefixed(&extensions, &body)) { return false; } switch (id) { case TLSEXT_TYPE_status_request: has_status_request = true; break; case kStatusRequestV2: has_status_request_v2 = true; break; case TLSEXT_TYPE_signature_algorithms: sigalgs = body; break; case TLSEXT_TYPE_signature_algorithms_cert: sigalgs_cert = body; break; case TLSEXT_TYPE_supported_groups: supported_groups = body; break; } } else if (java_extension.required) { return false; } } if (CBS_len(&extensions) != 0) { return false; } // JDK 11 never advertises X25519. It is not offered by default, and // -Djdk.tls.namedGroups=x25519 does not work. This is unusual: many modern // clients implement X25519. while (CBS_len(&supported_groups) > 0) { uint16_t group; if (!CBS_get_u16(&supported_groups, &group) || // group == SSL_GROUP_X25519) { return false; } } if ( // JDK 11 always sends the same contents in signature_algorithms and // signature_algorithms_cert. This is unusual: // signature_algorithms_cert, if omitted, is treated as if it were // signature_algorithms. sigalgs != sigalgs_cert || // When TLS 1.2 or below is enabled, JDK 11 sends status_request_v2 iff it // sends status_request. This is unusual: status_request_v2 is not widely // implemented. has_status_request != has_status_request_v2) { return false; } return true; } static bool decrypt_ech(SSL_HANDSHAKE *hs, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; CBS body; if (!ssl_client_hello_get_extension(client_hello, &body, TLSEXT_TYPE_encrypted_client_hello)) { return true; } uint8_t type; if (!CBS_get_u8(&body, &type)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } if (type != ECH_CLIENT_OUTER) { return true; } // This is a ClientHelloOuter ECH extension. Attempt to decrypt it. uint8_t config_id; uint16_t kdf_id, aead_id; CBS enc, payload; if (!CBS_get_u16(&body, &kdf_id) || // !CBS_get_u16(&body, &aead_id) || // !CBS_get_u8(&body, &config_id) || !CBS_get_u16_length_prefixed(&body, &enc) || !CBS_get_u16_length_prefixed(&body, &payload) || // CBS_len(&body) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); *out_alert = SSL_AD_DECODE_ERROR; return false; } { MutexReadLock lock(&ssl->ctx->lock); hs->ech_keys = UpRef(ssl->ctx->ech_keys); } if (!hs->ech_keys) { ssl->s3->ech_status = ssl_ech_rejected; return true; } for (const auto &config : hs->ech_keys->configs) { hs->ech_hpke_ctx.Reset(); if (config_id != config->ech_config().config_id || !config->SetupContext(hs->ech_hpke_ctx.get(), kdf_id, aead_id, enc)) { // Ignore the error and try another ECHConfig. ERR_clear_error(); continue; } bool is_decrypt_error; if (!ssl_client_hello_decrypt(hs, out_alert, &is_decrypt_error, &hs->ech_client_hello_buf, client_hello, payload)) { if (is_decrypt_error) { // Ignore the error and try another ECHConfig. ERR_clear_error(); // The |out_alert| calling convention currently relies on a default of // |SSL_AD_DECODE_ERROR|. https://crbug.com/boringssl/373 tracks // switching to sum types, which avoids this. *out_alert = SSL_AD_DECODE_ERROR; continue; } OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED); return false; } hs->ech_config_id = config_id; ssl->s3->ech_status = ssl_ech_accepted; return true; } // If we did not accept ECH, proceed with the ClientHelloOuter. Note this // could be key mismatch or ECH GREASE, so we must complete the handshake // as usual, except EncryptedExtensions will contain retry configs. ssl->s3->ech_status = ssl_ech_rejected; return true; } static bool extract_sni(SSL_HANDSHAKE *hs, uint8_t *out_alert, const SSL_CLIENT_HELLO *client_hello) { SSL *const ssl = hs->ssl; CBS sni; if (!ssl_client_hello_get_extension(client_hello, &sni, TLSEXT_TYPE_server_name)) { // No SNI extension to parse. // // Clear state in case we previously extracted SNI from ClientHelloOuter. ssl->s3->hostname.reset(); return true; } CBS server_name_list, host_name; uint8_t name_type; if (!CBS_get_u16_length_prefixed(&sni, &server_name_list) || // !CBS_get_u8(&server_name_list, &name_type) || // // Although the server_name extension was intended to be extensible to // new name types and multiple names, OpenSSL 1.0.x had a bug which meant // different name types will cause an error. Further, RFC 4366 originally // defined syntax inextensibly. RFC 6066 corrected this mistake, but // adding new name types is no longer feasible. // // Act as if the extensibility does not exist to simplify parsing. !CBS_get_u16_length_prefixed(&server_name_list, &host_name) || // CBS_len(&server_name_list) != 0 || // CBS_len(&sni) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); *out_alert = SSL_AD_DECODE_ERROR; return false; } if (name_type != TLSEXT_NAMETYPE_host_name || // CBS_len(&host_name) == 0 || // CBS_len(&host_name) > TLSEXT_MAXLEN_host_name || // CBS_contains_zero_byte(&host_name)) { OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION); *out_alert = SSL_AD_UNRECOGNIZED_NAME; return false; } // Copy the hostname as a string. char *raw = nullptr; if (!CBS_strdup(&host_name, &raw)) { *out_alert = SSL_AD_INTERNAL_ERROR; return false; } ssl->s3->hostname.reset(raw); return true; } static enum ssl_hs_wait_t do_read_client_hello(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; SSLMessage msg; if (!ssl->method->get_message(ssl, &msg)) { return ssl_hs_read_message; } if (!ssl_check_message_type(ssl, msg, SSL3_MT_CLIENT_HELLO)) { return ssl_hs_error; } SSL_CLIENT_HELLO client_hello; if (!SSL_parse_client_hello(ssl, &client_hello, CBS_data(&msg.body), CBS_len(&msg.body))) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } // ClientHello should be the end of the flight. We check this early to cover // all protocol versions. 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; } if (hs->config->handoff) { return ssl_hs_handoff; } uint8_t alert = SSL_AD_DECODE_ERROR; // We check for rejection status in case we've rewound the state machine after // determining `ClientHelloInner` is invalid. if (ssl->s3->ech_status != ssl_ech_rejected && !decrypt_ech(hs, &alert, &client_hello)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } // ECH may have changed which ClientHello we process. Update |msg| and // |client_hello| in case. if (!hs->GetClientHello(&msg, &client_hello)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } if (!extract_sni(hs, &alert, &client_hello)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } hs->state = state12_read_client_hello_after_ech; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_client_hello_after_ech(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; SSLMessage msg_unused; SSL_CLIENT_HELLO client_hello; if (!hs->GetClientHello(&msg_unused, &client_hello)) { return ssl_hs_error; } // Run the early callback. if (ssl->ctx->select_certificate_cb != nullptr) { switch (ssl->ctx->select_certificate_cb(&client_hello)) { case ssl_select_cert_retry: return ssl_hs_certificate_selection_pending; case ssl_select_cert_disable_ech: hs->ech_client_hello_buf.Reset(); hs->ech_keys = nullptr; hs->state = state12_read_client_hello; ssl->s3->ech_status = ssl_ech_rejected; return ssl_hs_ok; case ssl_select_cert_error: // Connection rejected. OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_REJECTED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; default: /* fallthrough */; } } // Freeze the version range after the early callback. if (!ssl_get_version_range(hs, &hs->min_version, &hs->max_version)) { return ssl_hs_error; } if (hs->config->jdk11_workaround && is_probably_jdk11_with_tls13(&client_hello)) { hs->apply_jdk11_workaround = true; } uint8_t alert = SSL_AD_DECODE_ERROR; if (!negotiate_version(hs, &alert, &client_hello)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } hs->client_version = client_hello.version; if (client_hello.random_len != SSL3_RANDOM_SIZE) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } OPENSSL_memcpy(ssl->s3->client_random, client_hello.random, client_hello.random_len); // Only null compression is supported. TLS 1.3 further requires the peer // advertise no other compression. if (OPENSSL_memchr(client_hello.compression_methods, 0, client_hello.compression_methods_len) == nullptr || (ssl_protocol_version(ssl) >= TLS1_3_VERSION && client_hello.compression_methods_len != 1)) { OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_COMPRESSION_LIST); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return ssl_hs_error; } // TLS extensions. if (!ssl_parse_clienthello_tlsext(hs, &client_hello)) { OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT); return ssl_hs_error; } hs->state = state12_cert_callback; return ssl_hs_ok; } static enum ssl_hs_wait_t do_cert_callback(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; // Call |cert_cb| to update server certificates if required. if (hs->config->cert->cert_cb != nullptr) { int rv = hs->config->cert->cert_cb(ssl, hs->config->cert->cert_cb_arg); if (rv == 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_CB_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } if (rv < 0) { return ssl_hs_x509_lookup; } } if (hs->ocsp_stapling_requested && ssl->ctx->legacy_ocsp_callback != nullptr) { switch (ssl->ctx->legacy_ocsp_callback( ssl, ssl->ctx->legacy_ocsp_callback_arg)) { case SSL_TLSEXT_ERR_OK: break; case SSL_TLSEXT_ERR_NOACK: hs->ocsp_stapling_requested = false; break; default: OPENSSL_PUT_ERROR(SSL, SSL_R_OCSP_CB_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } } if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) { // Jump to the TLS 1.3 state machine. hs->state = state12_tls13; return ssl_hs_ok; } // It should not be possible to negotiate TLS 1.2 with ECH. The // ClientHelloInner decoding function rejects ClientHellos which offer TLS 1.2 // or below. assert(ssl->s3->ech_status != ssl_ech_accepted); ssl->s3->early_data_reason = ssl_early_data_protocol_version; hs->state = state12_select_parameters; return ssl_hs_ok; } static enum ssl_hs_wait_t do_tls13(SSL_HANDSHAKE *hs) { enum ssl_hs_wait_t wait = tls13_server_handshake(hs); if (wait == ssl_hs_ok) { hs->state = state12_finish_server_handshake; return ssl_hs_ok; } return wait; } static enum ssl_hs_wait_t do_select_parameters(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; SSLMessage msg; SSL_CLIENT_HELLO client_hello; if (!hs->GetClientHello(&msg, &client_hello)) { return ssl_hs_error; } // Determine the ECDHE group to use, if we are to use ECDHE. uint16_t group_id = 0; bool has_ecdhe_group = tls1_get_shared_group(hs, &group_id); // Select the credential and cipher suite. This must be done after |cert_cb| // runs, so the final credential list is known. // // TODO(davidben): In the course of picking these, we also pick the ECDHE // group and signature algorithm. It would be tidier if we saved that decision // and avoided redoing it later. UniquePtr client_pref = ssl_parse_client_cipher_list(&client_hello); if (client_pref == nullptr) { return ssl_hs_error; } Array creds; if (!ssl_get_full_credential_list(hs, &creds)) { return ssl_hs_error; } uint8_t alert = SSL_AD_DECODE_ERROR; std::optional> allowed_cert_types = ssl_get_allowed_server_cert_types(hs, &client_hello, &alert); if (!allowed_cert_types.has_value()) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } TLS12ServerParams params; if (creds.empty()) { // The caller may have configured no credentials, but set a PSK callback. params = choose_params(hs, /*cred=*/nullptr, *allowed_cert_types, client_pref.get(), has_ecdhe_group); } else { // Select the first credential which works. for (SSLCredential *cred : creds) { ERR_clear_error(); params = choose_params(hs, cred, *allowed_cert_types, client_pref.get(), has_ecdhe_group); if (params.ok()) { hs->credential = UpRef(cred); break; } } } if (!params.ok()) { // The error from the last attempt is in the error queue. assert(ERR_peek_error() != 0); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } hs->new_cipher = params.cipher; hs->signature_algorithm = params.signature_algorithm; // |SSL_parse_client_hello| checks that |client_hello.session_id| is not too // large. hs->session_id.CopyFrom( Span(client_hello.session_id, client_hello.session_id_len)); // Determine whether we are doing session resumption. UniquePtr session; bool tickets_supported = false, renew_ticket = false; enum ssl_hs_wait_t wait = ssl_get_prev_session( hs, &session, &tickets_supported, &renew_ticket, &client_hello); if (wait != ssl_hs_ok) { return wait; } if (session) { if (session->extended_master_secret && !hs->extended_master_secret) { // A ClientHello without EMS that attempts to resume a session with EMS // is fatal to the connection. OPENSSL_PUT_ERROR(SSL, SSL_R_RESUMED_EMS_SESSION_WITHOUT_EMS_EXTENSION); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } if (!ssl_session_is_resumable(hs, session.get()) || // If the client offers the EMS extension, but the previous session // didn't use it, then negotiate a new session. hs->extended_master_secret != session->extended_master_secret) { session.reset(); } } if (session) { // Use the old session. hs->ticket_expected = renew_ticket; ssl->session = std::move(session); ssl->s3->session_reused = true; hs->can_release_private_key = true; } else { hs->ticket_expected = tickets_supported; ssl_set_session(ssl, nullptr); if (!ssl_get_new_session(hs)) { return ssl_hs_error; } // Assign a session ID if not using session tickets. if (!hs->ticket_expected && (ssl->ctx->session_cache_mode & SSL_SESS_CACHE_SERVER)) { hs->new_session->session_id.ResizeForOverwrite( SSL3_SSL_SESSION_ID_LENGTH); RAND_bytes(hs->new_session->session_id.data(), hs->new_session->session_id.size()); } } if (ssl->ctx->dos_protection_cb != nullptr && 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; } if (ssl->session == nullptr) { hs->new_session->cipher = hs->new_cipher; if (hs->new_session->cipher->algorithm_mkey & SSL_kECDHE) { assert(has_ecdhe_group); hs->new_session->group_id = group_id; } // Determine whether to request a client certificate. CertificateRequest may // only be sent in certificate-based ciphers. hs->cert_request = (hs->config->verify_mode & SSL_VERIFY_PEER) && ssl_cipher_uses_certificate_auth(hs->new_cipher); 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; } if (!ssl_negotiate_client_certificate_type(hs, &alert, &client_hello)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } } // HTTP/2 negotiation depends on the cipher suite, so ALPN negotiation was // deferred. Complete it now. if (!ssl_negotiate_alpn(hs, &alert, &client_hello)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } // Now that all parameters are known, initialize the handshake hash and hash // the ClientHello. if (!hs->transcript.InitHash(ssl_protocol_version(ssl), hs->new_cipher)) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } // Handback includes the whole handshake transcript, so we cannot free the // transcript buffer in the handback case. if (!hs->cert_request && !hs->handback) { hs->transcript.FreeBuffer(); } if (!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->state = state12_send_server_hello; return ssl_hs_ok; } static void copy_suffix(Span out, Span in) { out = out.last(in.size()); OPENSSL_memcpy(out.data(), in.data(), in.size()); } static enum ssl_hs_wait_t do_send_server_hello(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; // We only accept ChannelIDs on connections with ECDHE in order to avoid a // known attack while we fix ChannelID itself. if (hs->channel_id_negotiated && (hs->new_cipher->algorithm_mkey & SSL_kECDHE) == 0) { hs->channel_id_negotiated = false; } // If this is a resumption and the original handshake didn't support // ChannelID then we didn't record the original handshake hashes in the // session and so cannot resume with ChannelIDs. if (ssl->session != nullptr && ssl->session->original_handshake_hash.empty()) { hs->channel_id_negotiated = false; } SSL_HANDSHAKE_HINTS *const hints = hs->hints.get(); if (hints && !hs->hints_requested && hints->server_random_tls12.size() == SSL3_RANDOM_SIZE) { OPENSSL_memcpy(ssl->s3->server_random, hints->server_random_tls12.data(), SSL3_RANDOM_SIZE); } else { OPENSSL_timeval now = ssl_ctx_get_current_time(ssl->ctx.get()); CRYPTO_store_u32_be(ssl->s3->server_random, static_cast(now.tv_sec)); if (!RAND_bytes(ssl->s3->server_random + 4, SSL3_RANDOM_SIZE - 4)) { return ssl_hs_error; } if (hints && hs->hints_requested && !hints->server_random_tls12.CopyFrom(ssl->s3->server_random)) { return ssl_hs_error; } } // Implement the TLS 1.3 anti-downgrade feature. if (hs->max_version >= TLS1_3_VERSION) { if (ssl_protocol_version(ssl) == TLS1_2_VERSION) { if (hs->apply_jdk11_workaround) { // JDK 11 implements the TLS 1.3 downgrade signal, so we cannot send it // here. However, the signal is only effective if all TLS 1.2 // ServerHellos produced by the server are marked. Thus we send a // different non-standard signal for the time being, until JDK 11.0.2 is // released and clients have updated. copy_suffix(ssl->s3->server_random, kJDK11DowngradeRandom); } else { copy_suffix(ssl->s3->server_random, kTLS13DowngradeRandom); } } else { copy_suffix(ssl->s3->server_random, kTLS12DowngradeRandom); } } Span session_id; if (ssl->session != nullptr) { // Echo the session ID from the ClientHello to indicate resumption. session_id = hs->session_id; } else { session_id = hs->new_session->session_id; } ScopedCBB cbb; CBB body, session_id_bytes; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO) || !CBB_add_u16(&body, ssl->s3->version) || !CBB_add_bytes(&body, ssl->s3->server_random, SSL3_RANDOM_SIZE) || !CBB_add_u8_length_prefixed(&body, &session_id_bytes) || !CBB_add_bytes(&session_id_bytes, session_id.data(), session_id.size()) || !CBB_add_u16(&body, SSL_CIPHER_get_protocol_id(hs->new_cipher)) || !CBB_add_u8(&body, 0 /* no compression */) || !ssl_add_serverhello_tlsext(hs, &body) || !ssl_add_message_cbb(ssl, cbb.get())) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } if (ssl->session != nullptr) { // No additional hints to generate in resumption. if (hs->hints_requested) { return ssl_hs_hints_ready; } hs->state = state12_send_server_finished; } else { hs->state = state12_send_server_certificate; } return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_certificate(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; ScopedCBB cbb; if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) { assert(hs->credential != nullptr); if (!ssl_send_tls12_certificate(hs)) { return ssl_hs_error; } if (hs->certificate_status_expected) { CBB body, ocsp_response; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CERTIFICATE_STATUS) || !CBB_add_u8(&body, TLSEXT_STATUSTYPE_ocsp) || !CBB_add_u24_length_prefixed(&body, &ocsp_response) || !CBB_add_bytes( &ocsp_response, CRYPTO_BUFFER_data(hs->credential->ocsp_response.get()), CRYPTO_BUFFER_len(hs->credential->ocsp_response.get())) || !ssl_add_message_cbb(ssl, cbb.get())) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } } } // Assemble ServerKeyExchange parameters if needed. uint32_t alg_k = hs->new_cipher->algorithm_mkey; uint32_t alg_a = hs->new_cipher->algorithm_auth; if (ssl_cipher_requires_server_key_exchange(hs->new_cipher) || ((alg_a & SSL_aPSK) && hs->config->psk_identity_hint)) { // Pre-allocate enough room to comfortably fit an ECDHE public key. Prepend // the client and server randoms for the signing transcript. CBB child; if (!CBB_init(cbb.get(), SSL3_RANDOM_SIZE * 2 + 128) || !CBB_add_bytes(cbb.get(), ssl->s3->client_random, SSL3_RANDOM_SIZE) || !CBB_add_bytes(cbb.get(), ssl->s3->server_random, SSL3_RANDOM_SIZE)) { return ssl_hs_error; } // PSK ciphers begin with an identity hint. if (alg_a & SSL_aPSK) { size_t len = hs->config->psk_identity_hint == nullptr ? 0 : strlen(hs->config->psk_identity_hint.get()); if (!CBB_add_u16_length_prefixed(cbb.get(), &child) || !CBB_add_bytes(&child, (const uint8_t *)hs->config->psk_identity_hint.get(), len)) { return ssl_hs_error; } } if (alg_k & SSL_kECDHE) { assert(hs->new_session->group_id != 0); UniquePtr ssl_key_share = SSLKeyShare::Create(hs->new_session->group_id); if (ssl_key_share == nullptr || // !hs->key_shares.TryPushBack(std::move(ssl_key_share)) || // !CBB_add_u8(cbb.get(), NAMED_CURVE_TYPE) || // !CBB_add_u16(cbb.get(), hs->new_session->group_id) || // !CBB_add_u8_length_prefixed(cbb.get(), &child)) { return ssl_hs_error; } SSL_HANDSHAKE_HINTS *const hints = hs->hints.get(); bool hint_ok = false; if (hints && !hs->hints_requested && hints->ecdhe_group_id == hs->new_session->group_id && !hints->ecdhe_public_key.empty() && !hints->ecdhe_private_key.empty()) { CBS cbs = CBS(hints->ecdhe_private_key); hint_ok = hs->key_shares[0]->DeserializePrivateKey(&cbs); } if (hint_ok) { // Reuse the ECDH key from handshake hints. if (!CBB_add_bytes(&child, hints->ecdhe_public_key.data(), hints->ecdhe_public_key.size())) { return ssl_hs_error; } } else { // Generate a key, and emit the public half. if (!hs->key_shares[0]->Generate(&child)) { return ssl_hs_error; } // If generating hints, save the ECDHE key. if (hints && hs->hints_requested) { bssl::ScopedCBB private_key_cbb; if (!hints->ecdhe_public_key.CopyFrom(CBBAsSpan(&child)) || !CBB_init(private_key_cbb.get(), 32) || !hs->key_shares[0]->SerializePrivateKey(private_key_cbb.get()) || !CBBFinishArray(private_key_cbb.get(), &hints->ecdhe_private_key)) { return ssl_hs_error; } hints->ecdhe_group_id = hs->new_session->group_id; } } } else { assert(alg_k & SSL_kPSK); } if (!CBBFinishArray(cbb.get(), &hs->server_params)) { return ssl_hs_error; } } hs->state = state12_send_server_key_exchange; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_key_exchange(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (hs->server_params.size() == 0) { hs->state = state12_send_server_hello_done; return ssl_hs_ok; } ScopedCBB cbb; CBB body, child; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_KEY_EXCHANGE) || // |hs->server_params| contains a prefix for signing. hs->server_params.size() < 2 * SSL3_RANDOM_SIZE || !CBB_add_bytes(&body, hs->server_params.data() + 2 * SSL3_RANDOM_SIZE, hs->server_params.size() - 2 * SSL3_RANDOM_SIZE)) { return ssl_hs_error; } // Add a signature. if (ssl_cipher_uses_certificate_auth(hs->new_cipher)) { // Determine the signature algorithm. uint16_t signature_algorithm; if (!tls1_choose_signature_algorithm(hs, hs->credential.get(), &signature_algorithm)) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) { if (!CBB_add_u16(&body, signature_algorithm)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } } // Add space for the signature. const size_t max_sig_len = EVP_PKEY_size(hs->credential->pubkey.get()); uint8_t *ptr; if (!CBB_add_u16_length_prefixed(&body, &child) || !CBB_reserve(&child, &ptr, max_sig_len)) { return ssl_hs_error; } size_t sig_len; switch (ssl_private_key_sign(hs, ptr, &sig_len, max_sig_len, signature_algorithm, hs->server_params)) { case ssl_private_key_success: if (!CBB_did_write(&child, sig_len)) { return ssl_hs_error; } break; case ssl_private_key_failure: return ssl_hs_error; case ssl_private_key_retry: return ssl_hs_private_key_operation; } } hs->can_release_private_key = true; if (!ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } hs->server_params.Reset(); hs->state = state12_send_server_hello_done; return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_hello_done(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (hs->hints_requested) { return ssl_hs_hints_ready; } ScopedCBB cbb; CBB body; if (hs->cert_request) { CBB cert_types, sigalgs_cbb; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_CERTIFICATE_REQUEST) || !CBB_add_u8_length_prefixed(&body, &cert_types) || !CBB_add_u8(&cert_types, SSL3_CT_RSA_SIGN) || !CBB_add_u8(&cert_types, TLS_CT_ECDSA_SIGN) || (ssl_protocol_version(ssl) >= TLS1_2_VERSION && (!CBB_add_u16_length_prefixed(&body, &sigalgs_cbb) || !tls12_add_verify_sigalgs(hs, &sigalgs_cbb))) || !ssl_add_client_CA_list(hs, &body) || !ssl_add_message_cbb(ssl, cbb.get())) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } } if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_SERVER_HELLO_DONE) || !ssl_add_message_cbb(ssl, cbb.get())) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); return ssl_hs_error; } hs->state = state12_read_client_certificate; return ssl_hs_flush; } static enum ssl_hs_wait_t do_read_client_certificate(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (hs->handback && hs->new_cipher->algorithm_mkey == SSL_kECDHE) { return ssl_hs_handback; } if (!hs->cert_request) { hs->state = state12_verify_client_certificate; 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_CERTIFICATE)) { return ssl_hs_error; } if (!ssl_hash_message(hs, msg)) { return ssl_hs_error; } CBS certificate_msg = msg.body; uint8_t alert = SSL_AD_DECODE_ERROR; bool parse_ok; uint8_t *const out_sha256 = hs->config->retain_only_sha256_of_client_certs ? hs->new_session->peer_sha256 : nullptr; if (hs->peer_cert_type == TLSEXT_cert_type_rpk) { hs->new_session->peer_cert_type = TLSEXT_cert_type_rpk; parse_ok = ssl_parse_rpk_cert(&alert, &hs->new_session->peer_raw_public_key, &hs->peer_pubkey, out_sha256, &certificate_msg); } else { assert(hs->peer_cert_type == TLSEXT_cert_type_x509); hs->new_session->peer_cert_type = TLSEXT_cert_type_x509; parse_ok = ssl_parse_cert_chain(&alert, &hs->new_session->certs, &hs->peer_pubkey, out_sha256, &certificate_msg, ssl->ctx->pool.get()); } if (!parse_ok) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } if (CBS_len(&certificate_msg) != 0 || !ssl->ctx->x509_method->session_cache_objects(hs->new_session.get())) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } if (!ssl_session_has_peer_cred(hs->new_session.get())) { // No client certificate so the handshake buffer may be discarded. hs->transcript.FreeBuffer(); if (hs->config->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) { // Fail for TLS only if we required a certificate OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } // OpenSSL returns X509_V_OK when no certificates are received. This is // classed by them as a bug, but it's assumed by at least NGINX. hs->new_session->verify_result = X509_V_OK; } else if (hs->config->retain_only_sha256_of_client_certs) { // The hash will have been filled in. hs->new_session->peer_sha256_valid = true; } ssl->method->next_message(ssl); hs->state = state12_verify_client_certificate; return ssl_hs_ok; } static enum ssl_hs_wait_t do_verify_client_certificate(SSL_HANDSHAKE *hs) { if (ssl_session_has_peer_cred(hs->new_session.get())) { switch (ssl_verify_peer_cert(hs)) { case ssl_verify_ok: break; case ssl_verify_invalid: return ssl_hs_error; case ssl_verify_retry: return ssl_hs_certificate_verify; } } hs->state = state12_read_client_key_exchange; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_client_key_exchange(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_KEY_EXCHANGE)) { return ssl_hs_error; } CBS client_key_exchange = msg.body; uint32_t alg_k = hs->new_cipher->algorithm_mkey; uint32_t alg_a = hs->new_cipher->algorithm_auth; // If using a PSK key exchange, parse the PSK identity. if (alg_a & SSL_aPSK) { CBS psk_identity; // If using PSK, the ClientKeyExchange contains a psk_identity. If PSK, // then this is the only field in the message. if (!CBS_get_u16_length_prefixed(&client_key_exchange, &psk_identity) || ((alg_k & SSL_kPSK) && CBS_len(&client_key_exchange) != 0)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } if (CBS_len(&psk_identity) > PSK_MAX_IDENTITY_LEN || CBS_contains_zero_byte(&psk_identity)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER); return ssl_hs_error; } char *raw = nullptr; if (!CBS_strdup(&psk_identity, &raw)) { ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } hs->new_session->psk_identity.reset(raw); } // Depending on the key exchange method, compute |premaster_secret|. Array premaster_secret; if (alg_k & SSL_kRSA) { CBS encrypted_premaster_secret; if (!CBS_get_u16_length_prefixed(&client_key_exchange, &encrypted_premaster_secret) || CBS_len(&client_key_exchange) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } // Allocate a buffer large enough for an RSA decryption. Array decrypt_buf; if (!decrypt_buf.InitForOverwrite( EVP_PKEY_size(hs->credential->pubkey.get()))) { return ssl_hs_error; } // Decrypt with no padding. PKCS#1 padding will be removed as part of the // timing-sensitive code below. size_t decrypt_len; switch (ssl_private_key_decrypt(hs, decrypt_buf.data(), &decrypt_len, decrypt_buf.size(), encrypted_premaster_secret)) { case ssl_private_key_success: break; case ssl_private_key_failure: return ssl_hs_error; case ssl_private_key_retry: return ssl_hs_private_key_operation; } if (decrypt_len != decrypt_buf.size()) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); return ssl_hs_error; } CONSTTIME_SECRET(decrypt_buf.data(), decrypt_len); // Prepare a random premaster, to be used on invalid padding. See RFC 5246, // section 7.4.7.1. if (!premaster_secret.InitForOverwrite(SSL_MAX_MASTER_KEY_LENGTH) || !RAND_bytes(premaster_secret.data(), premaster_secret.size())) { return ssl_hs_error; } // The smallest padded premaster is 11 bytes of overhead. Small keys are // publicly invalid. if (decrypt_len < 11 + premaster_secret.size()) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECRYPTION_FAILED); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); return ssl_hs_error; } // Check the padding. See RFC 8017, section 7.2.2. size_t padding_len = decrypt_len - premaster_secret.size(); uint8_t good = constant_time_eq_int_8(decrypt_buf[0], 0) & constant_time_eq_int_8(decrypt_buf[1], 2); for (size_t i = 2; i < padding_len - 1; i++) { good &= ~constant_time_is_zero_8(decrypt_buf[i]); } good &= constant_time_is_zero_8(decrypt_buf[padding_len - 1]); // The premaster secret must begin with |client_version|. This too must be // checked in constant time (http://eprint.iacr.org/2003/052/). good &= constant_time_eq_8(decrypt_buf[padding_len], (unsigned)(hs->client_version >> 8)); good &= constant_time_eq_8(decrypt_buf[padding_len + 1], (unsigned)(hs->client_version & 0xff)); // Select, in constant time, either the decrypted premaster or the random // premaster based on |good|. for (size_t i = 0; i < premaster_secret.size(); i++) { premaster_secret[i] = constant_time_select_8( good, decrypt_buf[padding_len + i], premaster_secret[i]); } } else if (alg_k & SSL_kECDHE) { // Parse the ClientKeyExchange. CBS ciphertext; if (!CBS_get_u8_length_prefixed(&client_key_exchange, &ciphertext) || CBS_len(&client_key_exchange) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } // Decapsulate the premaster secret. uint8_t alert = SSL_AD_DECODE_ERROR; if (!hs->key_shares[0]->Decap(&premaster_secret, &alert, ciphertext)) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } // The key exchange state may now be discarded. hs->key_shares.clear(); } else if (!(alg_k & SSL_kPSK)) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE); return ssl_hs_error; } // For a PSK cipher suite, the actual pre-master secret is combined with the // pre-shared key. if (alg_a & SSL_aPSK) { if (hs->config->psk_server_callback == nullptr) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } // Look up the key for the identity. uint8_t psk[PSK_MAX_PSK_LEN]; unsigned psk_len = hs->config->psk_server_callback( ssl, hs->new_session->psk_identity.get(), psk, sizeof(psk)); if (psk_len > PSK_MAX_PSK_LEN) { OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR); return ssl_hs_error; } else if (psk_len == 0) { // PSK related to the given identity not found. OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNKNOWN_PSK_IDENTITY); return ssl_hs_error; } if (alg_k & SSL_kPSK) { // In plain PSK, other_secret is a block of 0s with the same length as the // pre-shared key. if (!premaster_secret.Init(psk_len)) { return ssl_hs_error; } } ScopedCBB new_premaster; CBB child; if (!CBB_init(new_premaster.get(), 2 + psk_len + 2 + premaster_secret.size()) || !CBB_add_u16_length_prefixed(new_premaster.get(), &child) || !CBB_add_bytes(&child, premaster_secret.data(), premaster_secret.size()) || !CBB_add_u16_length_prefixed(new_premaster.get(), &child) || !CBB_add_bytes(&child, psk, psk_len) || !CBBFinishArray(new_premaster.get(), &premaster_secret)) { return ssl_hs_error; } } if (!ssl_hash_message(hs, msg)) { return ssl_hs_error; } // Compute the master secret. hs->new_session->secret.ResizeForOverwrite(SSL3_MASTER_SECRET_SIZE); if (!tls1_generate_master_secret(hs, Span(hs->new_session->secret), premaster_secret)) { return ssl_hs_error; } hs->new_session->extended_master_secret = hs->extended_master_secret; // Declassify the secret to undo the RSA decryption validation above. We are // not currently running most of the TLS library with constant-time // validation. // TODO(crbug.com/42290551): Remove this and cover the TLS library too. CONSTTIME_DECLASSIFY(hs->new_session->secret.data(), hs->new_session->secret.size()); hs->can_release_private_key = true; ssl->method->next_message(ssl); hs->state = state12_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; // Only RSA and ECDSA client certificates are supported, so a // CertificateVerify is required if and only if there's a client certificate. if (!hs->peer_pubkey) { hs->transcript.FreeBuffer(); hs->state = state12_read_change_cipher_spec; 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_CERTIFICATE_VERIFY)) { return ssl_hs_error; } // The X.509 peer certificate must be valid for signing. (RPKs have no // keyUsage to enforce.) if (hs->new_session->peer_cert_type == TLSEXT_cert_type_x509) { const CRYPTO_BUFFER *leaf = sk_CRYPTO_BUFFER_value(hs->new_session->certs.get(), 0); CBS leaf_cbs; CRYPTO_BUFFER_init_CBS(leaf, &leaf_cbs); if (!ssl_cert_check_key_usage(&leaf_cbs, key_usage_digital_signature)) { return ssl_hs_error; } } CBS certificate_verify = msg.body, signature; // Determine the signature algorithm. uint16_t signature_algorithm = 0; if (ssl_protocol_version(ssl) >= TLS1_2_VERSION) { if (!CBS_get_u16(&certificate_verify, &signature_algorithm)) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } uint8_t alert = SSL_AD_DECODE_ERROR; if (!tls12_check_peer_sigalg(hs, &alert, signature_algorithm, hs->peer_pubkey.get())) { ssl_send_alert(ssl, SSL3_AL_FATAL, alert); return ssl_hs_error; } hs->new_session->peer_signature_algorithm = signature_algorithm; } else if (!tls1_get_legacy_signature_algorithm(&signature_algorithm, hs->peer_pubkey.get())) { OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_ERROR_UNSUPPORTED_CERTIFICATE_TYPE); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_CERTIFICATE); return ssl_hs_error; } // Parse and verify the signature. if (!CBS_get_u16_length_prefixed(&certificate_verify, &signature) || CBS_len(&certificate_verify) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } if (!ssl_public_key_verify(ssl, signature, signature_algorithm, hs->peer_pubkey.get(), hs->transcript.buffer())) { OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR); return ssl_hs_error; } // The handshake buffer is no longer necessary, and we may hash the current // message. hs->transcript.FreeBuffer(); if (!ssl_hash_message(hs, msg)) { return ssl_hs_error; } ssl->method->next_message(ssl); hs->state = state12_read_change_cipher_spec; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_change_cipher_spec(SSL_HANDSHAKE *hs) { if (hs->handback && hs->ssl->session != nullptr) { return ssl_hs_handback; } hs->state = state12_process_change_cipher_spec; return ssl_hs_read_change_cipher_spec; } static enum ssl_hs_wait_t do_process_change_cipher_spec(SSL_HANDSHAKE *hs) { if (!tls1_change_cipher_state(hs, evp_aead_open)) { return ssl_hs_error; } hs->state = state12_read_next_proto; return ssl_hs_ok; } static enum ssl_hs_wait_t do_read_next_proto(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (!hs->next_proto_neg_seen) { hs->state = state12_read_channel_id; 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_NEXT_PROTO) || !ssl_hash_message(hs, msg)) { return ssl_hs_error; } CBS next_protocol = msg.body, selected_protocol, padding; if (!CBS_get_u8_length_prefixed(&next_protocol, &selected_protocol) || !CBS_get_u8_length_prefixed(&next_protocol, &padding) || CBS_len(&next_protocol) != 0) { OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR); ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR); return ssl_hs_error; } if (!ssl->s3->next_proto_negotiated.CopyFrom(selected_protocol)) { return ssl_hs_error; } ssl->method->next_message(ssl); hs->state = state12_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 (!hs->channel_id_negotiated) { hs->state = state12_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->state = state12_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; enum ssl_hs_wait_t wait = ssl_get_finished(hs); if (wait != ssl_hs_ok) { return wait; } if (ssl->session != nullptr) { hs->state = state12_finish_server_handshake; } else { hs->state = state12_send_server_finished; } // If this is a full handshake with ChannelID then record the handshake // hashes in |hs->new_session| in case we need them to verify a // ChannelID signature on a resumption of this session in the future. if (ssl->session == nullptr && ssl->s3->channel_id_valid && !tls1_record_handshake_hashes_for_channel_id(hs)) { return ssl_hs_error; } return ssl_hs_ok; } static enum ssl_hs_wait_t do_send_server_finished(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (hs->ticket_expected) { const SSL_SESSION *session; UniquePtr session_copy; if (ssl->session == nullptr) { // Fix the timeout to measure from the ticket issuance time. ssl_session_rebase_time(ssl, hs->new_session.get()); session = hs->new_session.get(); } else { // We are renewing an existing session. Duplicate the session to adjust // the timeout. session_copy = SSL_SESSION_dup(ssl->session.get(), SSL_SESSION_INCLUDE_NONAUTH); if (!session_copy) { return ssl_hs_error; } ssl_session_rebase_time(ssl, session_copy.get()); session = session_copy.get(); } ScopedCBB cbb; CBB body, ticket; if (!ssl->method->init_message(ssl, cbb.get(), &body, SSL3_MT_NEW_SESSION_TICKET) || !CBB_add_u32(&body, session->timeout) || !CBB_add_u16_length_prefixed(&body, &ticket) || !ssl_encrypt_ticket(hs, &ticket, session) || // |ticket| may be empty to skip sending a ticket. In TLS 1.2, servers // skip sending tickets by sending empty NewSessionTicket, so no special // handling is needed. !ssl_add_message_cbb(ssl, cbb.get())) { return ssl_hs_error; } } if (!ssl->method->add_change_cipher_spec(ssl) || // !tls1_change_cipher_state(hs, evp_aead_seal) || // !ssl_send_finished(hs)) { return ssl_hs_error; } if (ssl->session != nullptr) { hs->state = state12_read_change_cipher_spec; } else { hs->state = state12_finish_server_handshake; } return ssl_hs_flush; } static enum ssl_hs_wait_t do_finish_server_handshake(SSL_HANDSHAKE *hs) { SSL *const ssl = hs->ssl; if (hs->handback) { return ssl_hs_handback; } ssl->method->on_handshake_complete(ssl); // If we aren't retaining peer certificates then we can discard it now. if (hs->new_session != nullptr && hs->config->retain_only_sha256_of_client_certs) { hs->new_session->certs.reset(); ssl->ctx->x509_method->session_clear(hs->new_session.get()); } bool has_new_session = hs->new_session != nullptr; if (has_new_session) { assert(ssl->session == nullptr); ssl->s3->established_session = std::move(hs->new_session); ssl->s3->established_session->not_resumable = false; } else { assert(ssl->session != nullptr); ssl->s3->established_session = UpRef(ssl->session); } hs->handshake_finalized = true; ssl->s3->initial_handshake_complete = true; if (has_new_session) { ssl_update_cache(ssl); } hs->state = state12_done; return ssl_hs_ok; } enum ssl_hs_wait_t ssl_server_handshake(SSL_HANDSHAKE *hs) { while (hs->state != state12_done) { enum ssl_hs_wait_t ret = ssl_hs_error; enum tls12_server_hs_state_t state = static_cast(hs->state); switch (state) { case state12_start_accept: ret = do_start_accept(hs); break; case state12_read_client_hello: ret = do_read_client_hello(hs); break; case state12_read_client_hello_after_ech: ret = do_read_client_hello_after_ech(hs); break; case state12_cert_callback: ret = do_cert_callback(hs); break; case state12_tls13: ret = do_tls13(hs); break; case state12_select_parameters: ret = do_select_parameters(hs); break; case state12_send_server_hello: ret = do_send_server_hello(hs); break; case state12_send_server_certificate: ret = do_send_server_certificate(hs); break; case state12_send_server_key_exchange: ret = do_send_server_key_exchange(hs); break; case state12_send_server_hello_done: ret = do_send_server_hello_done(hs); break; case state12_read_client_certificate: ret = do_read_client_certificate(hs); break; case state12_verify_client_certificate: ret = do_verify_client_certificate(hs); break; case state12_read_client_key_exchange: ret = do_read_client_key_exchange(hs); break; case state12_read_client_certificate_verify: ret = do_read_client_certificate_verify(hs); break; case state12_read_change_cipher_spec: ret = do_read_change_cipher_spec(hs); break; case state12_process_change_cipher_spec: ret = do_process_change_cipher_spec(hs); break; case state12_read_next_proto: ret = do_read_next_proto(hs); break; case state12_read_channel_id: ret = do_read_channel_id(hs); break; case state12_read_client_finished: ret = do_read_client_finished(hs); break; case state12_send_server_finished: ret = do_send_server_finished(hs); break; case state12_finish_server_handshake: ret = do_finish_server_handshake(hs); break; case state12_done: ret = ssl_hs_ok; break; } if (hs->state != state) { ssl_do_info_callback(hs->ssl, SSL_CB_ACCEPT_LOOP, 1); } if (ret != ssl_hs_ok) { return ret; } } ssl_do_info_callback(hs->ssl, SSL_CB_HANDSHAKE_DONE, 1); return ssl_hs_ok; } const char *ssl_server_handshake_state(SSL_HANDSHAKE *hs) { enum tls12_server_hs_state_t state = static_cast(hs->state); switch (state) { case state12_start_accept: return "TLS server start_accept"; case state12_read_client_hello: return "TLS server read_client_hello"; case state12_read_client_hello_after_ech: return "TLS server read_client_hello_after_ech"; case state12_cert_callback: return "TLS server cert_callback"; case state12_tls13: return tls13_server_handshake_state(hs); case state12_select_parameters: return "TLS server select_parameters"; case state12_send_server_hello: return "TLS server send_server_hello"; case state12_send_server_certificate: return "TLS server send_server_certificate"; case state12_send_server_key_exchange: return "TLS server send_server_key_exchange"; case state12_send_server_hello_done: return "TLS server send_server_hello_done"; case state12_read_client_certificate: return "TLS server read_client_certificate"; case state12_verify_client_certificate: return "TLS server verify_client_certificate"; case state12_read_client_key_exchange: return "TLS server read_client_key_exchange"; case state12_read_client_certificate_verify: return "TLS server read_client_certificate_verify"; case state12_read_change_cipher_spec: return "TLS server read_change_cipher_spec"; case state12_process_change_cipher_spec: return "TLS server process_change_cipher_spec"; case state12_read_next_proto: return "TLS server read_next_proto"; case state12_read_channel_id: return "TLS server read_channel_id"; case state12_read_client_finished: return "TLS server read_client_finished"; case state12_send_server_finished: return "TLS server send_server_finished"; case state12_finish_server_handshake: return "TLS server finish_server_handshake"; case state12_done: return "TLS server done"; } return "TLS server unknown"; } BSSL_NAMESPACE_END