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|
/*
* 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 <sys/param.h>
#include <errno.h>
#include <s2n.h>
#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->config->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->config->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_update_handshake_hashes(conn, &out));
}
/* 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));
/* Update the secrets, if necessary */
GUARD(s2n_tls13_handle_secrets(conn));
/* 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);
/* MD5 and SHA sum the handshake data too */
GUARD(s2n_conn_update_handshake_hashes(conn, &handshake_record));
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->config->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->config->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;
}
/* Update the secrets, if necessary */
GUARD(s2n_tls13_handle_secrets(conn));
/* 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;
}
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