/* * Copyright Amazon.com, Inc. or its affiliates. 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. * A copy of the License is located at * * http://aws.amazon.com/apache2.0 * * or in the "license" file accompanying this file. This file 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 "error/s2n_errno.h" #include "crypto/s2n_fips.h" #include "tls/s2n_async_pkey.h" #include "tls/s2n_cipher_suites.h" #include "tls/s2n_connection.h" #include "tls/s2n_record.h" #include "tls/s2n_resume.h" #include "tls/s2n_alerts.h" #include "tls/s2n_tls.h" #include "tls/s2n_tls13.h" #include "tls/s2n_tls13_handshake.h" #include "tls/s2n_kex.h" #include "stuffer/s2n_stuffer.h" #include "utils/s2n_safety.h" #include "utils/s2n_socket.h" #include "utils/s2n_random.h" #include "utils/s2n_str.h" /* clang-format off */ struct s2n_handshake_action { uint8_t record_type; uint8_t message_type; char writer; /* 'S' or 'C' for server or client, 'B' for both */ int (*handler[2]) (struct s2n_connection * conn); }; static int s2n_always_fail_send(struct s2n_connection *conn) { /* This state should never be sending a handshake message. */ S2N_ERROR(S2N_ERR_HANDSHAKE_UNREACHABLE); } static int s2n_always_fail_recv(struct s2n_connection *conn) { /* This state should never have an incoming handshake message. */ S2N_ERROR(S2N_ERR_HANDSHAKE_UNREACHABLE); } /* Client and Server handlers for each message type we support. * See http://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-7 for the list of handshake message types */ static struct s2n_handshake_action state_machine[] = { /* message_type_t = {Record type Message type Writer S2N_SERVER S2N_CLIENT } */ [CLIENT_HELLO] = {TLS_HANDSHAKE, TLS_CLIENT_HELLO, 'C', {s2n_establish_session, s2n_client_hello_send}}, [SERVER_HELLO] = {TLS_HANDSHAKE, TLS_SERVER_HELLO, 'S', {s2n_server_hello_send, s2n_server_hello_recv}}, [SERVER_NEW_SESSION_TICKET] = {TLS_HANDSHAKE, TLS_SERVER_NEW_SESSION_TICKET,'S', {s2n_server_nst_send, s2n_server_nst_recv}}, [SERVER_CERT] = {TLS_HANDSHAKE, TLS_CERTIFICATE, 'S', {s2n_server_cert_send, s2n_server_cert_recv}}, [SERVER_CERT_STATUS] = {TLS_HANDSHAKE, TLS_SERVER_CERT_STATUS, 'S', {s2n_server_status_send, s2n_server_status_recv}}, [SERVER_KEY] = {TLS_HANDSHAKE, TLS_SERVER_KEY, 'S', {s2n_server_key_send, s2n_server_key_recv}}, [SERVER_CERT_REQ] = {TLS_HANDSHAKE, TLS_CERT_REQ, 'S', {s2n_cert_req_send, s2n_cert_req_recv}}, [SERVER_HELLO_DONE] = {TLS_HANDSHAKE, TLS_SERVER_HELLO_DONE, 'S', {s2n_server_done_send, s2n_server_done_recv}}, [CLIENT_CERT] = {TLS_HANDSHAKE, TLS_CERTIFICATE, 'C', {s2n_client_cert_recv, s2n_client_cert_send}}, [CLIENT_KEY] = {TLS_HANDSHAKE, TLS_CLIENT_KEY, 'C', {s2n_client_key_recv, s2n_client_key_send}}, [CLIENT_CERT_VERIFY] = {TLS_HANDSHAKE, TLS_CERT_VERIFY, 'C', {s2n_client_cert_verify_recv, s2n_client_cert_verify_send}}, [CLIENT_CHANGE_CIPHER_SPEC] = {TLS_CHANGE_CIPHER_SPEC, 0, 'C', {s2n_client_ccs_recv, s2n_ccs_send}}, [CLIENT_FINISHED] = {TLS_HANDSHAKE, TLS_FINISHED, 'C', {s2n_client_finished_recv, s2n_client_finished_send}}, [SERVER_CHANGE_CIPHER_SPEC] = {TLS_CHANGE_CIPHER_SPEC, 0, 'S', {s2n_ccs_send, s2n_server_ccs_recv}}, [SERVER_FINISHED] = {TLS_HANDSHAKE, TLS_FINISHED, 'S', {s2n_server_finished_send, s2n_server_finished_recv}}, [APPLICATION_DATA] = {TLS_APPLICATION_DATA, 0, 'B', {s2n_always_fail_send, s2n_always_fail_recv}} }; /* * Client and Server handlers for TLS1.3. */ static struct s2n_handshake_action tls13_state_machine[] = { /* message_type_t = {Record type, Message type, Writer, {Server handler, client handler} } */ [CLIENT_HELLO] = {TLS_HANDSHAKE, TLS_CLIENT_HELLO, 'C', {s2n_establish_session, s2n_client_hello_send}}, [SERVER_HELLO] = {TLS_HANDSHAKE, TLS_SERVER_HELLO, 'S', {s2n_server_hello_send, s2n_server_hello_recv}}, [HELLO_RETRY_MSG] = {TLS_HANDSHAKE, TLS_SERVER_HELLO, 'S', {s2n_server_hello_retry_send, s2n_server_hello_retry_recv}}, [ENCRYPTED_EXTENSIONS] = {TLS_HANDSHAKE, TLS_ENCRYPTED_EXTENSIONS, 'S', {s2n_encrypted_extensions_send, s2n_encrypted_extensions_recv}}, [SERVER_CERT_REQ] = {TLS_HANDSHAKE, TLS_CERT_REQ, 'S', {s2n_tls13_cert_req_send, s2n_tls13_cert_req_recv}}, [SERVER_CERT] = {TLS_HANDSHAKE, TLS_CERTIFICATE, 'S', {s2n_server_cert_send, s2n_server_cert_recv}}, [SERVER_CERT_VERIFY] = {TLS_HANDSHAKE, TLS_CERT_VERIFY, 'S', {s2n_tls13_cert_verify_send, s2n_tls13_cert_verify_recv}}, [SERVER_FINISHED] = {TLS_HANDSHAKE, TLS_FINISHED, 'S', {s2n_tls13_server_finished_send, s2n_tls13_server_finished_recv}}, [CLIENT_CERT] = {TLS_HANDSHAKE, TLS_CERTIFICATE, 'C', {s2n_client_cert_recv, s2n_client_cert_send}}, [CLIENT_CERT_VERIFY] = {TLS_HANDSHAKE, TLS_CERT_VERIFY, 'C', {s2n_tls13_cert_verify_recv, s2n_tls13_cert_verify_send}}, [CLIENT_FINISHED] = {TLS_HANDSHAKE, TLS_FINISHED, 'C', {s2n_tls13_client_finished_recv, s2n_tls13_client_finished_send}}, /* Not used by TLS1.3, except to maintain middlebox compatibility */ [CLIENT_CHANGE_CIPHER_SPEC] = {TLS_CHANGE_CIPHER_SPEC, 0, 'C', {s2n_basic_ccs_recv, s2n_ccs_send}}, [SERVER_CHANGE_CIPHER_SPEC] = {TLS_CHANGE_CIPHER_SPEC, 0, 'S', {s2n_ccs_send, s2n_basic_ccs_recv}}, [APPLICATION_DATA] = {TLS_APPLICATION_DATA, 0, 'B', {s2n_always_fail_send, s2n_always_fail_recv}}, }; #define MESSAGE_NAME_ENTRY(msg) [msg] = #msg static const char *message_names[] = { MESSAGE_NAME_ENTRY(CLIENT_HELLO), MESSAGE_NAME_ENTRY(SERVER_HELLO), MESSAGE_NAME_ENTRY(ENCRYPTED_EXTENSIONS), MESSAGE_NAME_ENTRY(SERVER_NEW_SESSION_TICKET), MESSAGE_NAME_ENTRY(SERVER_CERT), MESSAGE_NAME_ENTRY(SERVER_CERT_STATUS), MESSAGE_NAME_ENTRY(SERVER_CERT_VERIFY), MESSAGE_NAME_ENTRY(SERVER_KEY), MESSAGE_NAME_ENTRY(SERVER_CERT_REQ), MESSAGE_NAME_ENTRY(SERVER_HELLO_DONE), MESSAGE_NAME_ENTRY(CLIENT_CERT), MESSAGE_NAME_ENTRY(CLIENT_KEY), MESSAGE_NAME_ENTRY(CLIENT_CERT_VERIFY), MESSAGE_NAME_ENTRY(CLIENT_CHANGE_CIPHER_SPEC), MESSAGE_NAME_ENTRY(CLIENT_FINISHED), MESSAGE_NAME_ENTRY(SERVER_CHANGE_CIPHER_SPEC), MESSAGE_NAME_ENTRY(SERVER_FINISHED), MESSAGE_NAME_ENTRY(HELLO_RETRY_MSG), MESSAGE_NAME_ENTRY(APPLICATION_DATA), }; /* Maximum number of valid handshakes */ #define S2N_HANDSHAKES_COUNT 512 /* Maximum number of messages in a handshake */ #define S2N_MAX_HANDSHAKE_LENGTH 32 /* We support different ordering of TLS Handshake messages, depending on what is being negotiated. There's also a dummy "INITIAL" handshake * that everything starts out as until we know better. */ static message_type_t handshakes[S2N_HANDSHAKES_COUNT][S2N_MAX_HANDSHAKE_LENGTH] = { [INITIAL] = { CLIENT_HELLO, SERVER_HELLO }, [NEGOTIATED] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, APPLICATION_DATA}, [NEGOTIATED | FULL_HANDSHAKE ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS ] ={ CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS | WITH_SESSION_TICKET ] ={ CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_HELLO_DONE, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | NO_CLIENT_CERT ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | WITH_SESSION_TICKET] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | NO_CLIENT_CERT | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | CLIENT_AUTH] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | CLIENT_AUTH | NO_CLIENT_CERT ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | CLIENT_AUTH | WITH_SESSION_TICKET] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | CLIENT_AUTH | NO_CLIENT_CERT | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS | CLIENT_AUTH] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS | CLIENT_AUTH | NO_CLIENT_CERT ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS | CLIENT_AUTH | WITH_SESSION_TICKET] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | OCSP_STATUS | CLIENT_AUTH | NO_CLIENT_CERT | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS | CLIENT_AUTH ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS | CLIENT_AUTH | NO_CLIENT_CERT ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS | CLIENT_AUTH | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CERT_VERIFY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | TLS12_PERFECT_FORWARD_SECRECY | OCSP_STATUS | CLIENT_AUTH | NO_CLIENT_CERT | WITH_SESSION_TICKET ] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CERT, SERVER_CERT_STATUS, SERVER_KEY, SERVER_CERT_REQ, SERVER_HELLO_DONE, CLIENT_CERT, CLIENT_KEY, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, SERVER_NEW_SESSION_TICKET, SERVER_CHANGE_CIPHER_SPEC, SERVER_FINISHED, APPLICATION_DATA }, }; /* * This selection of handshakes resembles the standard set, but with changes made to support tls1.3. * * These are just the basic handshakes. At the moment hello retries, session resumption, and early data are not supported. * * The CHANGE_CIPHER_SPEC messages are included only for middlebox compatibility. * See https://tools.ietf.org/html/rfc8446#appendix-D.4 */ static message_type_t tls13_handshakes[S2N_HANDSHAKES_COUNT][S2N_MAX_HANDSHAKE_LENGTH] = { [INITIAL] = { CLIENT_HELLO, SERVER_HELLO }, [INITIAL | HELLO_RETRY_REQUEST] = { CLIENT_HELLO, HELLO_RETRY_MSG }, [NEGOTIATED | FULL_HANDSHAKE] = { CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CHANGE_CIPHER_SPEC, ENCRYPTED_EXTENSIONS, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST] = { CLIENT_HELLO, HELLO_RETRY_MSG, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, HELLO_RETRY_MSG, SERVER_CHANGE_CIPHER_SPEC, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST | CLIENT_AUTH] = { CLIENT_HELLO, HELLO_RETRY_MSG, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_CERT_VERIFY, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST | CLIENT_AUTH | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, HELLO_RETRY_MSG, SERVER_CHANGE_CIPHER_SPEC, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_CERT_VERIFY, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST | CLIENT_AUTH | NO_CLIENT_CERT] = { CLIENT_HELLO, HELLO_RETRY_MSG, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | HELLO_RETRY_REQUEST | CLIENT_AUTH | NO_CLIENT_CERT | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, HELLO_RETRY_MSG, SERVER_CHANGE_CIPHER_SPEC, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH] = { CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_CERT_VERIFY, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CHANGE_CIPHER_SPEC, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_CERT, CLIENT_CERT_VERIFY, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | NO_CLIENT_CERT] = { CLIENT_HELLO, SERVER_HELLO, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CERT, CLIENT_FINISHED, APPLICATION_DATA }, [NEGOTIATED | FULL_HANDSHAKE | CLIENT_AUTH | NO_CLIENT_CERT | MIDDLEBOX_COMPAT] = { CLIENT_HELLO, SERVER_HELLO, SERVER_CHANGE_CIPHER_SPEC, ENCRYPTED_EXTENSIONS, SERVER_CERT_REQ, SERVER_CERT, SERVER_CERT_VERIFY, SERVER_FINISHED, CLIENT_CHANGE_CIPHER_SPEC, CLIENT_CERT, CLIENT_FINISHED, APPLICATION_DATA }, }; /* clang-format on */ #define MAX_HANDSHAKE_TYPE_LEN 152 static char handshake_type_str[S2N_HANDSHAKES_COUNT][MAX_HANDSHAKE_TYPE_LEN] = {0}; static const char* handshake_type_names[] = { "NEGOTIATED|", "FULL_HANDSHAKE|", "TLS12_PERFECT_FORWARD_SECRECY|", "OCSP_STATUS|", "CLIENT_AUTH|", "WITH_SESSION_TICKET|", "NO_CLIENT_CERT|", "HELLO_RETRY_REQUEST|", "MIDDLEBOX_COMPAT|", }; #define IS_TLS13_HANDSHAKE( conn ) ((conn)->actual_protocol_version == S2N_TLS13) #define ACTIVE_STATE_MACHINE( conn ) (IS_TLS13_HANDSHAKE(conn) ? tls13_state_machine : state_machine) #define ACTIVE_HANDSHAKES( conn ) (IS_TLS13_HANDSHAKE(conn) ? tls13_handshakes : handshakes) #define ACTIVE_MESSAGE( conn ) ACTIVE_HANDSHAKES(conn)[ (conn)->handshake.handshake_type ][ (conn)->handshake.message_number ] #define ACTIVE_STATE( conn ) ACTIVE_STATE_MACHINE(conn)[ ACTIVE_MESSAGE( (conn) ) ] #define CCS_STATE( conn ) (((conn)->mode == S2N_CLIENT) ? ACTIVE_STATE_MACHINE(conn)[SERVER_CHANGE_CIPHER_SPEC] \ : ACTIVE_STATE_MACHINE(conn)[CLIENT_CHANGE_CIPHER_SPEC] ) #define EXPECTED_RECORD_TYPE( conn ) ACTIVE_STATE( conn ).record_type #define EXPECTED_MESSAGE_TYPE( conn ) ACTIVE_STATE( conn ).message_type #define CONNECTION_WRITER( conn ) (conn->mode == S2N_CLIENT ? 'C' : 'S') #define CONNECTION_IS_WRITER( conn ) (ACTIVE_STATE(conn).writer == CONNECTION_WRITER(conn)) /* Used in our test cases */ message_type_t s2n_conn_get_current_message_type(struct s2n_connection *conn) { return ACTIVE_MESSAGE(conn); } static int s2n_advance_message(struct s2n_connection *conn) { /* Get the mode: 'C'lient or 'S'erver */ char previous_writer = ACTIVE_STATE(conn).writer; char this_mode = CONNECTION_WRITER(conn); /* Actually advance the message number */ conn->handshake.message_number++; /* When reading and using TLS1.3, skip optional change_cipher_spec states. */ if (ACTIVE_STATE(conn).writer != this_mode && EXPECTED_RECORD_TYPE(conn) == TLS_CHANGE_CIPHER_SPEC && IS_TLS13_HANDSHAKE(conn)) { conn->handshake.message_number++; } /* Set TCP_QUICKACK to avoid artificial delay during the handshake */ GUARD(s2n_socket_quickack(conn)); /* If optimized io hasn't been enabled or if the caller started out with a corked socket, * we don't mess with it */ if (!conn->corked_io || s2n_socket_was_corked(conn)) { return 0; } /* Are we changing I/O directions */ if (ACTIVE_STATE(conn).writer == previous_writer || ACTIVE_STATE(conn).writer == 'A') { return 0; } /* We're the new writer */ if (ACTIVE_STATE(conn).writer == this_mode) { if (s2n_connection_is_managed_corked(conn)) { /* Set TCP_CORK/NOPUSH */ GUARD(s2n_socket_write_cork(conn)); } return 0; } /* We're the new reader, or we reached the "B" writer stage indicating that we're at the application data stage - uncork the data */ if (s2n_connection_is_managed_corked(conn)) { GUARD(s2n_socket_write_uncork(conn)); } return 0; } int s2n_generate_new_client_session_id(struct s2n_connection *conn) { if (conn->mode == S2N_SERVER) { struct s2n_blob session_id = { .data = conn->session_id, .size = S2N_TLS_SESSION_ID_MAX_LEN }; /* Generate a new session id */ GUARD_AS_POSIX(s2n_get_public_random_data(&session_id)); conn->session_id_len = S2N_TLS_SESSION_ID_MAX_LEN; } return 0; } /* Lets the server flag whether a HelloRetryRequest is needed while processing extensions */ int s2n_set_hello_retry_required(struct s2n_connection *conn) { notnull_check(conn); ENSURE_POSIX(conn->actual_protocol_version >= S2N_TLS13, S2N_ERR_INVALID_HELLO_RETRY); conn->handshake.handshake_type |= HELLO_RETRY_REQUEST; return S2N_SUCCESS; } bool s2n_is_hello_retry_message(struct s2n_connection *conn) { return (ACTIVE_MESSAGE(conn) == HELLO_RETRY_MSG); } bool s2n_is_hello_retry_handshake(struct s2n_connection *conn) { return conn->handshake.handshake_type & HELLO_RETRY_REQUEST; } int s2n_conn_set_handshake_type(struct s2n_connection *conn) { if (conn->handshake.handshake_type & HELLO_RETRY_REQUEST) { ENSURE_POSIX(conn->actual_protocol_version >= S2N_TLS13, S2N_ERR_INVALID_HELLO_RETRY); conn->handshake.handshake_type = HELLO_RETRY_REQUEST; } else { conn->handshake.handshake_type = INITIAL; } /* A handshake type has been negotiated */ conn->handshake.handshake_type |= NEGOTIATED; s2n_cert_auth_type client_cert_auth_type; GUARD(s2n_connection_get_client_auth_type(conn, &client_cert_auth_type)); if (conn->mode == S2N_CLIENT && client_cert_auth_type == S2N_CERT_AUTH_REQUIRED) { /* If we're a client, and Client Auth is REQUIRED, then the Client must expect the CLIENT_CERT_REQ Message */ conn->handshake.handshake_type |= CLIENT_AUTH; } else if (conn->mode == S2N_SERVER && client_cert_auth_type != S2N_CERT_AUTH_NONE) { /* If we're a server, and Client Auth is REQUIRED or OPTIONAL, then the server must send the CLIENT_CERT_REQ Message*/ conn->handshake.handshake_type |= CLIENT_AUTH; } if (IS_TLS13_HANDSHAKE(conn)) { /* Use middlebox compatibility mode for TLS1.3 by default. * For now, only disable it when QUIC support is enabled. */ if (!conn->quic_enabled) { conn->handshake.handshake_type |= MIDDLEBOX_COMPAT; } conn->handshake.handshake_type |= FULL_HANDSHAKE; return 0; } if (conn->config->use_tickets) { if (conn->session_ticket_status == S2N_DECRYPT_TICKET) { if (!s2n_decrypt_session_ticket(conn)) { return 0; } if (s2n_config_is_encrypt_decrypt_key_available(conn->config) == 1) { conn->session_ticket_status = S2N_NEW_TICKET; conn->handshake.handshake_type |= WITH_SESSION_TICKET; } /* If a session ticket is presented by the client, then skip lookup in Session ID server cache */ goto skip_cache_lookup; } if (conn->session_ticket_status == S2N_NEW_TICKET) { conn->handshake.handshake_type |= WITH_SESSION_TICKET; } } /* If a TLS session is resumed, the Server should respond in its ServerHello with the same SessionId the * Client sent in the ClientHello. */ if (conn->actual_protocol_version <= S2N_TLS12 && conn->mode == S2N_SERVER && s2n_allowed_to_cache_connection(conn)) { int r = s2n_resume_from_cache(conn); if (r == S2N_SUCCESS || (r < 0 && S2N_ERROR_IS_BLOCKING(s2n_errno))) { return r; } } skip_cache_lookup: if (conn->mode == S2N_CLIENT && conn->client_session_resumed == 1) { return 0; } /* If we're doing full handshake, generate a new session id. */ GUARD(s2n_generate_new_client_session_id(conn)); /* If we get this far, it's a full handshake */ conn->handshake.handshake_type |= FULL_HANDSHAKE; if (s2n_kex_is_ephemeral(conn->secure.cipher_suite->key_exchange_alg)) { conn->handshake.handshake_type |= TLS12_PERFECT_FORWARD_SECRECY; } if (s2n_server_can_send_ocsp(conn) || s2n_server_sent_ocsp(conn)) { conn->handshake.handshake_type |= OCSP_STATUS; } return 0; } int s2n_conn_set_handshake_no_client_cert(struct s2n_connection *conn) { s2n_cert_auth_type client_cert_auth_type; GUARD(s2n_connection_get_client_auth_type(conn, &client_cert_auth_type)); S2N_ERROR_IF(client_cert_auth_type != S2N_CERT_AUTH_OPTIONAL, S2N_ERR_BAD_MESSAGE); conn->handshake.handshake_type |= NO_CLIENT_CERT; return 0; } int s2n_conn_set_handshake_read_block(struct s2n_connection *conn) { notnull_check(conn); conn->handshake.paused = 1; return 0; } int s2n_conn_clear_handshake_read_block(struct s2n_connection *conn) { notnull_check(conn); conn->handshake.paused = 0; return 0; } const char *s2n_connection_get_last_message_name(struct s2n_connection *conn) { notnull_check_ptr(conn); return message_names[ACTIVE_MESSAGE(conn)]; } const char *s2n_connection_get_handshake_type_name(struct s2n_connection *conn) { notnull_check_ptr(conn); int handshake_type = conn->handshake.handshake_type; if (handshake_type == INITIAL) { return "INITIAL"; } if (handshake_type_str[handshake_type][0] != '\0') { return handshake_type_str[handshake_type]; } /* Compute handshake_type_str[handshake_type] */ char *p = handshake_type_str[handshake_type]; char *end = p + sizeof(handshake_type_str[0]); for (int i = 0; i < s2n_array_len(handshake_type_names); ++i) { if (handshake_type & (1 << i)) { p = s2n_strcpy(p, end, handshake_type_names[i]); } } if (p != handshake_type_str[handshake_type] && '|' == *(p - 1)) { *(p - 1) = '\0'; } return handshake_type_str[handshake_type]; } /* Writing is relatively straight forward, simply write each message out as a record, * we may fragment a message across multiple records, but we never coalesce multiple * messages into single records. * Precondition: secure outbound I/O has already been flushed */ static int s2n_handshake_write_io(struct s2n_connection *conn) { uint8_t record_type = EXPECTED_RECORD_TYPE(conn); s2n_blocked_status blocked = S2N_NOT_BLOCKED; /* Populate handshake.io with header/payload for the current state, once. * Check wiped instead of s2n_stuffer_data_available to differentiate between the initial call * to s2n_handshake_write_io and a repeated call after an EWOULDBLOCK. */ if (s2n_stuffer_is_wiped(&conn->handshake.io)) { if (record_type == TLS_HANDSHAKE) { GUARD(s2n_handshake_write_header(&conn->handshake.io, ACTIVE_STATE(conn).message_type)); } GUARD(ACTIVE_STATE(conn).handler[conn->mode] (conn)); if (record_type == TLS_HANDSHAKE) { GUARD(s2n_handshake_finish_header(&conn->handshake.io)); } } /* Write the handshake data to records in fragment sized chunks */ struct s2n_blob out = {0}; while (s2n_stuffer_data_available(&conn->handshake.io) > 0) { uint16_t max_payload_size = 0; GUARD_AS_POSIX(s2n_record_max_write_payload_size(conn, &max_payload_size)); out.size = MIN(s2n_stuffer_data_available(&conn->handshake.io), max_payload_size); out.data = s2n_stuffer_raw_read(&conn->handshake.io, out.size); notnull_check(out.data); if (conn->quic_enabled) { GUARD_AS_POSIX(s2n_quic_write_handshake_message(conn, &out)); } else { GUARD(s2n_record_write(conn, record_type, &out)); } /* MD5 and SHA sum the handshake data too */ if (record_type == TLS_HANDSHAKE) { GUARD(s2n_conn_pre_handshake_hashes_update(conn)); GUARD(s2n_conn_update_handshake_hashes(conn, &out)); GUARD(s2n_conn_post_handshake_hashes_update(conn)); } /* Actually send the record. We could block here. Assume the caller will call flush before coming back. */ GUARD(s2n_flush(conn, &blocked)); } /* We're done sending the last record, reset everything */ GUARD(s2n_stuffer_wipe(&conn->out)); GUARD(s2n_stuffer_wipe(&conn->handshake.io)); /* Advance the state machine */ GUARD(s2n_advance_message(conn)); return 0; } /* * Returns: * 1 - more data is needed to complete the handshake message. * 0 - we read the whole handshake message. * -1 - error processing the handshake message. */ static int s2n_read_full_handshake_message(struct s2n_connection *conn, uint8_t *message_type) { uint32_t current_handshake_data = s2n_stuffer_data_available(&conn->handshake.io); if (current_handshake_data < TLS_HANDSHAKE_HEADER_LENGTH) { /* The message may be so badly fragmented that we don't even read the full header, take * what we can and then continue to the next record read iteration. */ if (s2n_stuffer_data_available(&conn->in) < (TLS_HANDSHAKE_HEADER_LENGTH - current_handshake_data)) { GUARD(s2n_stuffer_copy(&conn->in, &conn->handshake.io, s2n_stuffer_data_available(&conn->in))); return 1; } /* Get the remainder of the header */ GUARD(s2n_stuffer_copy(&conn->in, &conn->handshake.io, (TLS_HANDSHAKE_HEADER_LENGTH - current_handshake_data))); } uint32_t handshake_message_length; GUARD(s2n_handshake_parse_header(conn, message_type, &handshake_message_length)); S2N_ERROR_IF(handshake_message_length > S2N_MAXIMUM_HANDSHAKE_MESSAGE_LENGTH, S2N_ERR_BAD_MESSAGE); uint32_t bytes_to_take = handshake_message_length - s2n_stuffer_data_available(&conn->handshake.io); bytes_to_take = MIN(bytes_to_take, s2n_stuffer_data_available(&conn->in)); /* If the record is handshake data, add it to the handshake buffer */ GUARD(s2n_stuffer_copy(&conn->in, &conn->handshake.io, bytes_to_take)); /* If we have the whole handshake message, then success */ if (s2n_stuffer_data_available(&conn->handshake.io) == handshake_message_length) { return 0; } /* We don't have the whole message, so we'll need to go again */ GUARD(s2n_stuffer_reread(&conn->handshake.io)); return 1; } static int s2n_handshake_conn_update_hashes(struct s2n_connection *conn) { uint8_t message_type; uint32_t handshake_message_length; GUARD(s2n_stuffer_reread(&conn->handshake.io)); GUARD(s2n_handshake_parse_header(conn, &message_type, &handshake_message_length)); struct s2n_blob handshake_record = {0}; handshake_record.data = conn->handshake.io.blob.data; handshake_record.size = TLS_HANDSHAKE_HEADER_LENGTH + handshake_message_length; notnull_check(handshake_record.data); GUARD(s2n_conn_pre_handshake_hashes_update(conn)); /* MD5 and SHA sum the handshake data too */ GUARD(s2n_conn_update_handshake_hashes(conn, &handshake_record)); GUARD(s2n_conn_post_handshake_hashes_update(conn)); return 0; } static int s2n_handshake_handle_sslv2(struct s2n_connection *conn) { S2N_ERROR_IF(ACTIVE_MESSAGE(conn) != CLIENT_HELLO, S2N_ERR_BAD_MESSAGE); /* Add the message to our handshake hashes */ struct s2n_blob hashed = {.data = conn->header_in.blob.data + 2,.size = 3 }; GUARD(s2n_conn_update_handshake_hashes(conn, &hashed)); hashed.data = conn->in.blob.data; hashed.size = s2n_stuffer_data_available(&conn->in); GUARD(s2n_conn_update_handshake_hashes(conn, &hashed)); /* Handle an SSLv2 client hello */ GUARD(s2n_stuffer_copy(&conn->in, &conn->handshake.io, s2n_stuffer_data_available(&conn->in))); /* Set the client hello version */ conn->client_hello_version = S2N_SSLv2; /* Execute the state machine handler */ int r = ACTIVE_STATE(conn).handler[conn->mode](conn); GUARD(s2n_stuffer_wipe(&conn->handshake.io)); /* We're done with the record, wipe it */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); if (r < 0) { /* Don't invoke blinding on some of the common errors */ switch (s2n_errno) { case S2N_ERR_CANCELLED: case S2N_ERR_CIPHER_NOT_SUPPORTED: case S2N_ERR_PROTOCOL_VERSION_UNSUPPORTED: conn->closed = 1; break; case S2N_ERR_IO_BLOCKED: case S2N_ERR_ASYNC_BLOCKED: /* A blocking condition is retryable, so we should return without killing the connection. */ S2N_ERROR_PRESERVE_ERRNO(); break; default: GUARD(s2n_connection_kill(conn)); } return r; } conn->in_status = ENCRYPTED; /* Advance the state machine */ GUARD(s2n_advance_message(conn)); return 0; } static int s2n_try_delete_session_cache(struct s2n_connection *conn) { notnull_check(conn); if (s2n_allowed_to_cache_connection(conn) > 0) { conn->config->cache_delete(conn, conn->config->cache_delete_data, conn->session_id, conn->session_id_len); } return 0; } /* Reading is a little more complicated than writing as the TLS RFCs allow content * types to be interleaved at the record layer. We may get an alert message * during the handshake phase, or messages of types that we don't support (e.g. * HEARTBEAT messages), or during renegotiations we may even get application * data messages that need to be handled by the application. The latter is punted * for now (s2n does not support renegotiations). */ static int s2n_handshake_read_io(struct s2n_connection *conn) { uint8_t record_type; uint8_t message_type; int isSSLv2 = 0; /* Fill conn->in stuffer necessary for the handshake. * If using TCP, read a record. If using QUIC, read a message. */ if (conn->quic_enabled) { record_type = TLS_HANDSHAKE; GUARD_AS_POSIX(s2n_quic_read_handshake_message(conn, &message_type)); } else { GUARD(s2n_read_full_record(conn, &record_type, &isSSLv2)); } if (isSSLv2) { S2N_ERROR_IF(record_type != SSLv2_CLIENT_HELLO, S2N_ERR_BAD_MESSAGE); GUARD(s2n_handshake_handle_sslv2(conn)); } /* Now we have a record, but it could be a partial fragment of a message, or it might * contain several messages. */ S2N_ERROR_IF(record_type == TLS_APPLICATION_DATA, S2N_ERR_BAD_MESSAGE); if (record_type == TLS_CHANGE_CIPHER_SPEC) { /* TLS1.3 can receive unexpected CCS messages at any point in the handshake * due to a peer operating in middlebox compatibility mode. * However, when operating in QUIC mode, S2N should not accept ANY CCS messages, * including these unexpected ones.*/ if (!IS_TLS13_HANDSHAKE(conn) || conn->quic_enabled) { ENSURE_POSIX(EXPECTED_RECORD_TYPE(conn) == TLS_CHANGE_CIPHER_SPEC, S2N_ERR_BAD_MESSAGE); ENSURE_POSIX(!CONNECTION_IS_WRITER(conn), S2N_ERR_BAD_MESSAGE); } S2N_ERROR_IF(s2n_stuffer_data_available(&conn->in) != 1, S2N_ERR_BAD_MESSAGE); GUARD(s2n_stuffer_copy(&conn->in, &conn->handshake.io, s2n_stuffer_data_available(&conn->in))); GUARD(CCS_STATE(conn).handler[conn->mode] (conn)); GUARD(s2n_stuffer_wipe(&conn->handshake.io)); /* We're done with the record, wipe it */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); conn->in_status = ENCRYPTED; /* Advance the state machine if this was an expected message */ if (EXPECTED_RECORD_TYPE(conn) == TLS_CHANGE_CIPHER_SPEC && !CONNECTION_IS_WRITER(conn)) { GUARD(s2n_advance_message(conn)); } return 0; } else if (record_type != TLS_HANDSHAKE) { if (record_type == TLS_ALERT) { GUARD(s2n_process_alert_fragment(conn)); } /* Ignore record types that we don't support */ /* We're done with the record, wipe it */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); conn->in_status = ENCRYPTED; return 0; } /* Record is a handshake message */ S2N_ERROR_IF(s2n_stuffer_data_available(&conn->in) == 0, S2N_ERR_BAD_MESSAGE); while (s2n_stuffer_data_available(&conn->in)) { /* We're done with negotiating but we have trailing data in this record. Bail on the handshake. */ S2N_ERROR_IF(EXPECTED_RECORD_TYPE(conn) == TLS_APPLICATION_DATA, S2N_ERR_BAD_MESSAGE); int r; GUARD((r = s2n_read_full_handshake_message(conn, &message_type))); /* Do we need more data? This happens for message fragmentation */ if (r == 1) { /* Break out of this inner loop, but since we're not changing the state, the * outer loop in s2n_handshake_io() will read another record. */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); conn->in_status = ENCRYPTED; return 0; } s2n_cert_auth_type client_cert_auth_type; GUARD(s2n_connection_get_client_auth_type(conn, &client_cert_auth_type)); /* If we're a Client, and received a ClientCertRequest message, and ClientAuth * is set to optional, then switch the State Machine that we're using to expect the ClientCertRequest. */ if (conn->mode == S2N_CLIENT && client_cert_auth_type == S2N_CERT_AUTH_OPTIONAL && message_type == TLS_CERT_REQ) { conn->handshake.handshake_type |= CLIENT_AUTH; } /* According to rfc6066 section 8, server may choose not to send "CertificateStatus" message even if it has * sent "status_request" extension in the ServerHello message. */ if (conn->mode == S2N_CLIENT && EXPECTED_MESSAGE_TYPE(conn) == TLS_SERVER_CERT_STATUS && message_type != TLS_SERVER_CERT_STATUS) { conn->handshake.handshake_type &= ~OCSP_STATUS; } ENSURE_POSIX(record_type == EXPECTED_RECORD_TYPE(conn), S2N_ERR_BAD_MESSAGE); ENSURE_POSIX(message_type == EXPECTED_MESSAGE_TYPE(conn), S2N_ERR_BAD_MESSAGE); ENSURE_POSIX(!CONNECTION_IS_WRITER(conn), S2N_ERR_BAD_MESSAGE); /* Call the relevant handler */ r = ACTIVE_STATE(conn).handler[conn->mode] (conn); /* Don't update handshake hashes until after the handler has executed since some handlers need to read the * hash values before they are updated. */ GUARD(s2n_handshake_conn_update_hashes(conn)); GUARD(s2n_stuffer_wipe(&conn->handshake.io)); if (r < 0) { /* Don't invoke blinding on some of the common errors */ switch (s2n_errno) { case S2N_ERR_CANCELLED: case S2N_ERR_CIPHER_NOT_SUPPORTED: case S2N_ERR_PROTOCOL_VERSION_UNSUPPORTED: conn->closed = 1; break; case S2N_ERR_IO_BLOCKED: case S2N_ERR_ASYNC_BLOCKED: /* A blocking condition is retryable, so we should return without killing the connection. */ S2N_ERROR_PRESERVE_ERRNO(); break; default: GUARD(s2n_connection_kill(conn)); } return r; } /* Advance the state machine */ GUARD(s2n_advance_message(conn)); } /* We're done with the record, wipe it */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); conn->in_status = ENCRYPTED; return 0; } static int s2n_handle_retry_state(struct s2n_connection *conn) { /* If we were blocked reading or writing a record, then the handler is waiting on * external data. The handler will know how to continue, so we should call the * handler right away. We aren't going to read more handshake data yet or proceed * to the next handler because the current message has not finished processing. */ s2n_errno = S2N_ERR_OK; const int r = ACTIVE_STATE(conn).handler[conn->mode] (conn); if (r < 0 && S2N_ERROR_IS_BLOCKING(s2n_errno)) { /* If the handler is still waiting for data, return control to the caller. */ S2N_ERROR_PRESERVE_ERRNO(); } if (!CONNECTION_IS_WRITER(conn)) { /* We're done parsing the record, reset everything */ GUARD(s2n_stuffer_wipe(&conn->header_in)); GUARD(s2n_stuffer_wipe(&conn->in)); conn->in_status = ENCRYPTED; } if (r < 0) { /* There is some other problem and we should kill the connection. */ if (conn->session_id_len) { s2n_try_delete_session_cache(conn); } GUARD(s2n_connection_kill(conn)); S2N_ERROR_PRESERVE_ERRNO(); } if (CONNECTION_IS_WRITER(conn)) { /* If we're the writer and handler just finished, update the record header if * needed and let the s2n_handshake_write_io write the data to the socket */ if (EXPECTED_RECORD_TYPE(conn) == TLS_HANDSHAKE) { GUARD(s2n_handshake_finish_header(&conn->handshake.io)); } } else { /* The read handler processed the record successfully, we are done with this * record. Advance the state machine. */ GUARD(s2n_advance_message(conn)); } return 0; } int s2n_negotiate(struct s2n_connection *conn, s2n_blocked_status *blocked) { notnull_check(conn); notnull_check(blocked); while (ACTIVE_STATE(conn).writer != 'B') { errno = 0; s2n_errno = S2N_ERR_OK; /* Flush any pending I/O or alert messages */ GUARD(s2n_flush(conn, blocked)); /* If the handshake was paused, retry the current message */ if (conn->handshake.paused) { *blocked = S2N_BLOCKED_ON_APPLICATION_INPUT; GUARD(s2n_handle_retry_state(conn)); } if (CONNECTION_IS_WRITER(conn)) { *blocked = S2N_BLOCKED_ON_WRITE; const int write_result = s2n_handshake_write_io(conn); if (write_result < 0) { if (!S2N_ERROR_IS_BLOCKING(s2n_errno)) { /* Non-retryable write error. The peer might have sent an alert. Try and read it. */ const int write_errno = errno; const int write_s2n_errno = s2n_errno; const char *write_s2n_debug_str = s2n_debug_str; if (s2n_handshake_read_io(conn) < 0 && s2n_errno == S2N_ERR_ALERT) { /* s2n_handshake_read_io has set s2n_errno */ S2N_ERROR_PRESERVE_ERRNO(); } else { /* Let the write error take precedence if we didn't read an alert. */ errno = write_errno; s2n_errno = write_s2n_errno; s2n_debug_str = write_s2n_debug_str; S2N_ERROR_PRESERVE_ERRNO(); } } if (s2n_errno == S2N_ERR_ASYNC_BLOCKED) { *blocked = S2N_BLOCKED_ON_APPLICATION_INPUT; } S2N_ERROR_PRESERVE_ERRNO(); } } else { *blocked = S2N_BLOCKED_ON_READ; const int read_result = s2n_handshake_read_io(conn); if (read_result < 0) { /* One blocking condition is waiting on the session resumption cache. */ /* So we don't want to delete anything if we are blocked. */ if (!S2N_ERROR_IS_BLOCKING(s2n_errno) && conn->session_id_len) { s2n_try_delete_session_cache(conn); } if (s2n_errno == S2N_ERR_ASYNC_BLOCKED) { *blocked = S2N_BLOCKED_ON_APPLICATION_INPUT; } S2N_ERROR_PRESERVE_ERRNO(); } } /* If the handshake has just ended, free up memory */ if (ACTIVE_STATE(conn).writer == 'B') { GUARD(s2n_stuffer_resize(&conn->handshake.io, 0)); } } *blocked = S2N_NOT_BLOCKED; return 0; }