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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_hash_record PORTABLE C */
/* 6.1.7 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function hashes an outgoing TLS record to generate the Message */
/* Authentication Code (MAC) value that is placed at the end of all */
/* encrypted TLS messages. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* sequence_num Record sequence number */
/* header Record header */
/* header_length Length of record header */
/* packet_ptr TLS record packet */
/* offset Offset to TLS record in packet*/
/* length Length of payload data */
/* record_hash Pointer to output hash buffer */
/* hash_length Length of hash */
/* mac_secret Key used for MAC generation */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* [nx_crypto_operation] Crypto operation */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_verify_mac Verify record MAC checksum */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* supported chained packet, */
/* resulting in version 6.1 */
/* 06-02-2021 Timothy Stapko Modified comment(s), */
/* fixed compiler warning, */
/* resulting in version 6.1.7 */
/* */
/**************************************************************************/
UINT _nx_secure_tls_hash_record(NX_SECURE_TLS_SESSION *tls_session,
ULONG sequence_num[NX_SECURE_TLS_SEQUENCE_NUMBER_SIZE],
UCHAR *header, UINT header_length, NX_PACKET *packet_ptr,
ULONG offset, UINT length, UCHAR *record_hash, UINT *hash_length,
UCHAR *mac_secret)
{
UINT hash_size;
UINT status = NX_SECURE_TLS_MISSING_CRYPTO_ROUTINE;
const NX_CRYPTO_METHOD *authentication_method;
UCHAR adjusted_sequence_num[8];
VOID *metadata;
UINT metadata_size;
VOID *handler = NX_NULL;
ULONG current_length;
NX_PARAMETER_NOT_USED(header_length);
/* We need to generate a Message Authentication Code (MAC) for each record during an "active" TLS session
(following a ChangeCipherSpec message). The hash algorithm is determined by the ciphersuite, and HMAC
is used with that hash algorithm to protect the TLS record contents from tampering.
The MAC is generated as:
HMAC_hash(MAC_write_secret, seq_num + type + version + length + data);
*/
if (tls_session -> nx_secure_tls_session_ciphersuite == NX_NULL)
{
/* Likely internal error since at this point ciphersuite negotiation was theoretically completed. */
return(NX_SECURE_TLS_UNKNOWN_CIPHERSUITE);
}
/* Get our authentication method from the ciphersuite. */
authentication_method = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash;
metadata = tls_session -> nx_secure_hash_mac_metadata_area;
metadata_size = tls_session -> nx_secure_hash_mac_metadata_size;
/* Get the hash size and MAC secret for our current session. */
hash_size = tls_session -> nx_secure_tls_session_ciphersuite -> nx_secure_tls_hash_size;
/* Correct the endianness of our sequence number before hashing. */
adjusted_sequence_num[0] = (UCHAR)(sequence_num[1] >> 24);
adjusted_sequence_num[1] = (UCHAR)(sequence_num[1] >> 16);
adjusted_sequence_num[2] = (UCHAR)(sequence_num[1] >> 8);
adjusted_sequence_num[3] = (UCHAR)(sequence_num[1]);
adjusted_sequence_num[4] = (UCHAR)(sequence_num[0] >> 24);
adjusted_sequence_num[5] = (UCHAR)(sequence_num[0] >> 16);
adjusted_sequence_num[6] = (UCHAR)(sequence_num[0] >> 8);
adjusted_sequence_num[7] = (UCHAR)(sequence_num[0]);
if (authentication_method -> nx_crypto_init)
{
status = authentication_method -> nx_crypto_init((NX_CRYPTO_METHOD*)authentication_method,
mac_secret,
(NX_CRYPTO_KEY_SIZE)(hash_size << 3),
&handler,
metadata,
metadata_size);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
/* TLS header type, version, and length are in the proper order. */
if (authentication_method -> nx_crypto_operation != NX_NULL)
{
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_INITIALIZE,
handler,
(NX_CRYPTO_METHOD*)authentication_method,
mac_secret,
(NX_CRYPTO_KEY_SIZE)(hash_size << 3),
NX_NULL,
0,
NX_NULL,
NX_NULL,
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
adjusted_sequence_num,
8,
NX_NULL,
NX_NULL,
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
header,
5,
NX_NULL,
NX_NULL,
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
/* Locate to start packet of TLS record payload. */
while (packet_ptr)
{
current_length = (ULONG)(packet_ptr -> nx_packet_append_ptr - packet_ptr -> nx_packet_prepend_ptr);
if (offset >= current_length)
{
/* Move to next packet. */
offset -= current_length;
packet_ptr = packet_ptr -> nx_packet_next;
}
else
{
/* Found offset in current packet. */
break;
}
}
/* Hash TLS record payload. */
while ((length > 0) && packet_ptr)
{
current_length = (ULONG)(packet_ptr -> nx_packet_append_ptr - packet_ptr -> nx_packet_prepend_ptr);
current_length -= offset;
offset = 0;
if (current_length > length)
{
current_length = length;
}
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_UPDATE,
handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
&packet_ptr -> nx_packet_prepend_ptr[offset],
current_length,
NX_NULL,
NX_NULL,
0,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
length -= current_length;
packet_ptr = packet_ptr -> nx_packet_next;
}
if (length > 0)
{
/* Not all TLS record payload is hashed. */
return(NX_SECURE_TLS_INVALID_PACKET);
}
status = authentication_method -> nx_crypto_operation(NX_CRYPTO_HASH_CALCULATE,
handler,
(NX_CRYPTO_METHOD*)authentication_method,
NX_NULL,
0,
NX_NULL,
0,
NX_NULL,
record_hash,
NX_SECURE_TLS_MAX_HASH_SIZE,
metadata,
metadata_size,
NX_NULL,
NX_NULL);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
#ifdef NX_SECURE_KEY_CLEAR
NX_SECURE_MEMSET(adjusted_sequence_num, 0, 8);
#endif /* NX_SECURE_KEY_CLEAR */
}
if (authentication_method -> nx_crypto_cleanup)
{
status = authentication_method -> nx_crypto_cleanup(metadata);
if(status != NX_CRYPTO_SUCCESS)
{
return(status);
}
}
/* Return how many bytes our hash is since the caller doesn't necessarily know. */
*hash_length = hash_size;
return(status);
}