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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** Transport Layer Security (TLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_tls.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_send_record PORTABLE C */
/* 6.1.8 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function encapsulates the TLS record layer send */
/* functionality. The incoming packet data is wrapped in */
/* a TLS record, which includes a header and footer (for */
/* encrypted data). Also, all encryption of application */
/* data is handled here. */
/* */
/* INPUT */
/* */
/* tls_session Pointer to TLS session */
/* send_packet Packet data to send */
/* record_type TLS record type */
/* wait_option Suspension option */
/* */
/* OUTPUT */
/* */
/* status Record send status */
/* */
/* CALLS */
/* */
/* _nx_secure_tls_record_hash_calculate Calculate hash of record */
/* _nx_secure_tls_record_hash_initialize Initialize hash of record */
/* _nx_secure_tls_record_hash_update Update hash of record */
/* _nx_secure_tls_record_payload_encrypt Encrypt payload */
/* _nx_secure_tls_session_iv_size_get Get IV size for this session. */
/* nx_packet_data_append Append data to packet */
/* nx_tcp_socket_send Send packet */
/* tx_mutex_get Get protection mutex */
/* tx_mutex_put Put protection mutex */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_client_handshake TLS client state machine */
/* _nx_secure_tls_send_handshake_record Send TLS handshake record */
/* _nx_secure_tls_server_handshake TLS server state machine */
/* _nx_secure_tls_session_end End of a session */
/* _nx_secure_tls_session_receive_records */
/* Receive TLS records */
/* _nx_secure_tls_session_send Send session packet */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), and */
/* fixed race condition for */
/* multithread transmission, */
/* resulting in version 6.1 */
/* 06-02-2021 Timothy Stapko Modified comment(s), */
/* resulting in version 6.1.7 */
/* 08-02-2021 Timothy Stapko Modified comment(s), */
/* used wait forever on */
/* transmission mutex, */
/* resulting in version 6.1.8 */
/* */
/**************************************************************************/
UINT _nx_secure_tls_send_record(NX_SECURE_TLS_SESSION *tls_session, NX_PACKET *send_packet,
UCHAR record_type, ULONG wait_option)
{
UINT status;
UINT message_length;
UCHAR *mac_secret;
UCHAR *record_header;
UCHAR record_hash[NX_SECURE_TLS_MAX_HASH_SIZE];
UINT hash_length;
UCHAR *hash_data;
ULONG hash_data_length;
ULONG length;
USHORT iv_size = 0;
NX_PACKET *current_packet;
/* Length of the data in the packet. */
length = send_packet -> nx_packet_length;
if ((tls_session -> nx_secure_tls_tcp_socket) &&
(tls_session -> nx_secure_tls_tcp_socket -> nx_tcp_socket_ip_ptr) &&
(tx_thread_identify() == &(tls_session -> nx_secure_tls_tcp_socket -> nx_tcp_socket_ip_ptr -> nx_ip_thread)))
{
/* No wait is allowed for IP thread to avoid dead lock. */
wait_option = 0;
}
tx_mutex_put(&_nx_secure_tls_protection);
/* Get transmit mutex first. */
status = tx_mutex_get(&(tls_session -> nx_secure_tls_session_transmit_mutex), TX_WAIT_FOREVER);
tx_mutex_get(&_nx_secure_tls_protection, TX_WAIT_FOREVER);
if (status)
{
/* Unable to send due to another thread is still transmitting. */
return(NX_SECURE_TLS_TRANSMIT_LOCKED);
}
/* See if this is an active session, we need to account for the IV if the session cipher
uses one. TLS 1.3 does not use an explicit IV so don't add it.*/
if (tls_session -> nx_secure_tls_local_session_active
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
&& !tls_session->nx_secure_tls_1_3
#endif
)
{
/* Get the size of the IV used by the session cipher. */
status = _nx_secure_tls_session_iv_size_get(tls_session, &iv_size);
if (status != NX_SUCCESS)
{
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(status);
}
/* Ensure there is enough room for the IV data. */
if ((ULONG)(send_packet -> nx_packet_prepend_ptr - send_packet -> nx_packet_data_start) < iv_size)
{
/* Return an invalid packet error. */
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(NX_SECURE_TLS_INVALID_PACKET);
}
/* Back off the pointer to the point before the IV data allocation
(can be 0). Increases length since we are moving the prepend pointer. */
send_packet -> nx_packet_prepend_ptr -= iv_size;
send_packet -> nx_packet_length += iv_size;
}
/* Ensure there is enough room for the record header. */
if ((ULONG)(send_packet -> nx_packet_prepend_ptr - send_packet -> nx_packet_data_start) < NX_SECURE_TLS_RECORD_HEADER_SIZE)
{
/* Return an invalid packet error. */
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(NX_SECURE_TLS_INVALID_PACKET);
}
/* Get a pointer to our record header which is now right after the prepend pointer. */
record_header = send_packet -> nx_packet_prepend_ptr - NX_SECURE_TLS_RECORD_HEADER_SIZE;
/* Build the TLS record header. */
record_header[0] = record_type;
/* Set the version number. */
record_header[1] = (UCHAR)((tls_session -> nx_secure_tls_protocol_version & 0xFF00) >> 8);
record_header[2] = (UCHAR)(tls_session -> nx_secure_tls_protocol_version & 0x00FF);
/* Set the length of the record prior to hashing and encryption - this is because
the hashing is done on the record as if it were not encrypted so any additional
padding or IVs, etc. added to the length would invalidate the hash. We update
the length following the encryption below. */
message_length = length;
record_header[3] = (UCHAR)((length & 0xFF00) >> 8);
record_header[4] = (UCHAR)(length & 0x00FF);
/* If the session is active, hash and encrypt the record payload using
the session keys and chosen ciphersuite. */
if (tls_session -> nx_secure_tls_local_session_active)
{
/*************************************************************************************************************/
if (tls_session -> nx_secure_tls_session_ciphersuite == NX_NULL)
{
/* Likely internal error since at this point ciphersuite negotiation was theoretically completed. */
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(NX_SECURE_TLS_UNKNOWN_CIPHERSUITE);
}
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
/* TLS 1.3 records have the record type appended in a single byte. */
if(tls_session->nx_secure_tls_1_3)
{
/* If in a TLS 1.3 encrypted session, write the message type to the end. */
status = nx_packet_data_append(send_packet, (UCHAR*)(&record_type), 1,
tls_session -> nx_secure_tls_packet_pool, wait_option);
if(status != NX_SUCCESS)
{
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(status);
}
/* Record header type is APPLICATION DATA for all TLS 1.3 encrypted records. */
record_type = NX_SECURE_TLS_APPLICATION_DATA;
record_header[0] = record_type;
}
#endif
/* TLS 1.3 does uses AEAD instead of per-record hash MACs. */
if (
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
!tls_session->nx_secure_tls_1_3 &&
#endif
tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash -> nx_crypto_operation)
{
/***** HASHING *****/
/* Select our proper MAC secret for hashing. */
if (tls_session -> nx_secure_tls_socket_type == NX_SECURE_TLS_SESSION_TYPE_SERVER)
{
/* If we are a server, we need to use the client's MAC secret. */
mac_secret = tls_session -> nx_secure_tls_key_material.nx_secure_tls_server_write_mac_secret;
}
else
{
/* We are a client, so use the server's MAC secret. */
mac_secret = tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_write_mac_secret;
}
/* Account for large records that exceed the packet size and are chained in multiple packets
such as large certificate messages with multiple certificates.
tls_session->nx_secure_hash_mac_metadata_area is persistent across the following calls, so it's important
to not do anything that might change the contents of that buffer until the hash is calculated after the loop! */
current_packet = send_packet;
/* Initialize the hash routine with our MAC secret, sequence number, and header. */
status = _nx_secure_tls_record_hash_initialize(tls_session, tls_session -> nx_secure_tls_local_sequence_number,
record_header, 5, &hash_length, mac_secret);
/* Check return from hash routine initialization. */
if (status != NX_SUCCESS)
{
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(status);
}
/* Start the hash data after the header and IV. */
hash_data = current_packet -> nx_packet_prepend_ptr + iv_size;
hash_data_length = (ULONG)(current_packet -> nx_packet_append_ptr - current_packet -> nx_packet_prepend_ptr) - iv_size;
/* Walk packet chain. */
do
{
/* Update the hash with the data. */
status = _nx_secure_tls_record_hash_update(tls_session, hash_data,
(UINT)hash_data_length);
/* Advance the packet pointer to the next packet in the chain. */
current_packet = current_packet -> nx_packet_next;
if (current_packet != NX_NULL)
{
hash_data = current_packet -> nx_packet_prepend_ptr;
hash_data_length = (ULONG)(current_packet -> nx_packet_append_ptr - current_packet -> nx_packet_prepend_ptr);
}
} while (current_packet != NX_NULL);
/* Generate the hash on the plaintext data. */
_nx_secure_tls_record_hash_calculate(tls_session, record_hash, &hash_length);
/* Release the protection before suspending on nx_packet_data_append. */
tx_mutex_put(&_nx_secure_tls_protection);
/* Append the hash to the plaintext data in the last packet before encryption. */
status = nx_packet_data_append(send_packet, record_hash, hash_length,
tls_session -> nx_secure_tls_packet_pool, wait_option);
#ifdef NX_SECURE_KEY_CLEAR
NX_SECURE_MEMSET(record_hash, 0, sizeof(record_hash));
#endif /* NX_SECURE_KEY_CLEAR */
/* Get the protection after nx_packet_data_append. */
tx_mutex_get(&_nx_secure_tls_protection, TX_WAIT_FOREVER);
}
/*************************************************************************************************************/
/***** ENCRYPTION *****/
status = _nx_secure_tls_record_payload_encrypt(tls_session, send_packet, tls_session -> nx_secure_tls_local_sequence_number, record_type);
if (status != NX_SUCCESS)
{
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(status);
}
/*************************************************************************************************************/
/* Increment the sequence number. */
if ((tls_session -> nx_secure_tls_local_sequence_number[0] + 1) == 0)
{
/* Check for overflow of the 32-bit number. */
tls_session -> nx_secure_tls_local_sequence_number[1]++;
}
tls_session -> nx_secure_tls_local_sequence_number[0]++;
}
/* The encryption above may have changed the payload length, so get the length from
the packet and use it to update the record header. */
message_length = send_packet -> nx_packet_length;
/* Set the length of the record. */
record_header[3] = (UCHAR)((message_length & 0xFF00) >> 8);
record_header[4] = (UCHAR)(message_length & 0x00FF);
/* Adjust packet length */
send_packet -> nx_packet_prepend_ptr -= NX_SECURE_TLS_RECORD_HEADER_SIZE;
send_packet -> nx_packet_length += NX_SECURE_TLS_RECORD_HEADER_SIZE;
/* Release the protection before suspending on nx_tcp_socket_send. */
tx_mutex_put(&_nx_secure_tls_protection);
/* Send the TCP packet(s) containing our record. */
status = nx_tcp_socket_send(tls_session -> nx_secure_tls_tcp_socket, send_packet, wait_option);
#ifdef NX_SECURE_KEY_CLEAR
if (tls_session -> nx_secure_tls_local_session_active)
{
/* Clear all data in chained packet. */
current_packet = send_packet;
while (current_packet)
{
NX_SECURE_MEMSET(current_packet -> nx_packet_prepend_ptr, 0,
(ULONG)current_packet -> nx_packet_append_ptr -
(ULONG)current_packet -> nx_packet_prepend_ptr);
current_packet = current_packet -> nx_packet_next;
}
}
#endif /* NX_SECURE_KEY_CLEAR */
/* Get the protection after nx_tcp_socket_send. */
tx_mutex_get(&_nx_secure_tls_protection, TX_WAIT_FOREVER);
/* Release transmit mutex. */
tx_mutex_put(&(tls_session -> nx_secure_tls_session_transmit_mutex));
return(status);
}