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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"
#include "nx_secure_x509.h"
#ifdef NX_SECURE_ENABLE_DTLS
#include "nx_secure_dtls.h"
#endif /* NX_SECURE_ENABLE_DTLS */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_process_certificate_request PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function processes an incoming TLS Certificate request */
/* message, typically sent by a TLS Server to request a client */
/* certificate for authentication. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* packet_buffer Pointer to message data */
/* message_length Length of message data (bytes)*/
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_secure_x509_local_device_certificate_get */
/* Get the local certificate */
/* */
/* CALLED BY */
/* */
/* _nx_secure_dtls_client_handshake DTLS client state machine */
/* _nx_secure_tls_client_handshake TLS client state machine */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _nx_secure_tls_process_certificate_request(NX_SECURE_TLS_SESSION *tls_session,
UCHAR *packet_buffer, UINT message_length)
{
UINT length;
UINT cert_types_length;
UCHAR cert_type;
UINT i;
NX_SECURE_X509_CERT *local_certificate = NX_NULL;
UCHAR expected_cert_type = 0;
UINT status;
#if (NX_SECURE_TLS_TLS_1_2_ENABLED)
UINT sign_algs_length;
UINT sign_alg;
UINT expected_sign_alg = 0;
#endif
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
UINT extension_total_length;
UINT extension_length;
UINT extension_type;
#endif
/* Structure:
* | 1 | <Cert types count> | 2 | <Sig algs length> |
* | Cert types count | Cert types (1 byte each) | Sig Hash algorithms length | Algorithms (2 bytes each) |
*/
/* Use our length as an index into the buffer. */
length = 0;
/* Get the local certificate. */
if (tls_session -> nx_secure_tls_credentials.nx_secure_tls_active_certificate != NX_NULL)
{
local_certificate = tls_session -> nx_secure_tls_credentials.nx_secure_tls_active_certificate;
}
else
{
/* Get reference to local device certificate. NX_NULL is passed for name to get default entry. */
status = _nx_secure_x509_local_device_certificate_get(&tls_session -> nx_secure_tls_credentials.nx_secure_tls_certificate_store,
NX_NULL, &local_certificate);
if (status != NX_SUCCESS)
{
local_certificate = NX_NULL;
}
}
if (local_certificate != NX_NULL)
{
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
if (tls_session -> nx_secure_tls_1_3)
{
tls_session -> nx_secure_tls_signature_algorithm = 0;
/* TLS1.3 uses RSASSA-PSS instead of RSASSA-PKCS. RSASSA-PSS is not supported now. */
if (local_certificate -> nx_secure_x509_public_algorithm == NX_SECURE_TLS_X509_TYPE_RSA)
{
return(NX_SECURE_TLS_UNSUPPORTED_CERT_SIGN_TYPE);
}
/* In TLS 1.3, the signing curve is constrained. */
switch (local_certificate -> nx_secure_x509_private_key.ec_private_key.nx_secure_ec_named_curve)
{
case NX_CRYPTO_EC_SECP256R1:
expected_sign_alg = NX_SECURE_TLS_SIGNATURE_ECDSA_SHA256;
break;
case NX_CRYPTO_EC_SECP384R1:
expected_sign_alg = NX_SECURE_TLS_SIGNATURE_ECDSA_SHA384;
break;
case NX_CRYPTO_EC_SECP521R1:
expected_sign_alg = NX_SECURE_TLS_SIGNATURE_ECDSA_SHA512;
break;
default:
return(NX_SECURE_TLS_UNSUPPORTED_CERT_SIGN_ALG);
}
}
else
#endif
{
if (local_certificate -> nx_secure_x509_public_algorithm == NX_SECURE_TLS_X509_TYPE_RSA)
{
expected_cert_type = NX_SECURE_TLS_CERT_TYPE_RSA_SIGN;
#if (NX_SECURE_TLS_TLS_1_2_ENABLED)
expected_sign_alg = NX_SECURE_TLS_SIGNATURE_RSA_SHA256;
#endif
}
#ifdef NX_SECURE_ENABLE_ECC_CIPHERSUITE
else if (local_certificate -> nx_secure_x509_public_algorithm == NX_SECURE_TLS_X509_TYPE_EC)
{
expected_cert_type = NX_SECURE_TLS_CERT_TYPE_ECDSA_SIGN;
#if (NX_SECURE_TLS_TLS_1_2_ENABLED)
expected_sign_alg = NX_SECURE_TLS_SIGNATURE_ECDSA_SHA256;
#endif
}
#endif /* NX_SECURE_ENABLE_ECC_CIPHERSUITE */
}
}
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
/*
struct {
opaque certificate_request_context<0..2^8-1>;
Extension extensions<2..2^16-1>;
} CertificateRequest;
*/
if (tls_session -> nx_secure_tls_1_3)
{
/* Skip certificate request context. */
length = length + 1 + packet_buffer[length];
extension_total_length = (UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]);
length += 2;
/* Make sure what we extracted makes sense. */
if ((length + extension_total_length) > message_length)
{
return(NX_SECURE_TLS_INCORRECT_MESSAGE_LENGTH);
}
/* Find SignatureAlgorithms extension. */
/* Note: Other extensions will be processed in the future. */
while (length < message_length)
{
extension_type = (UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]);
length += 2;
extension_length = (UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]);
length += 2;
if (extension_type == NX_SECURE_TLS_EXTENSION_SIGNATURE_ALGORITHMS)
{
break;
}
length += extension_length;
}
if (length >= message_length)
{
return(NX_SECURE_TLS_UNSUPPORTED_CERT_SIGN_ALG);
}
}
else
#endif
{
/* Extract the count of certificate types from the incoming data. */
cert_types_length = packet_buffer[length];
length += 1;
/* Make sure what we extracted makes sense. */
if (cert_types_length > message_length)
{
return(NX_SECURE_TLS_INCORRECT_MESSAGE_LENGTH);
}
cert_type = NX_SECURE_TLS_CERT_TYPE_NONE;
for (i = 0; i < cert_types_length; ++i)
{
if (packet_buffer[length] == expected_cert_type)
{
/* We found a type we support. */
cert_type = packet_buffer[length];
}
length += 1;
}
/* Make sure our certificate type is one we support. */
if (cert_type != expected_cert_type)
{
return(NX_SECURE_TLS_UNSUPPORTED_CERT_SIGN_TYPE);
}
}
#if (NX_SECURE_TLS_TLS_1_2_ENABLED)
/* TLS 1.2 CertificateRequest contains a list of signature algorithms that
is not included in earlier TLS versions. */
#ifdef NX_SECURE_ENABLE_DTLS
if (tls_session -> nx_secure_tls_protocol_version == NX_SECURE_TLS_VERSION_TLS_1_2 ||
tls_session -> nx_secure_tls_protocol_version == NX_SECURE_DTLS_VERSION_1_2)
#else
if (tls_session -> nx_secure_tls_protocol_version == NX_SECURE_TLS_VERSION_TLS_1_2)
#endif /* NX_SECURE_ENABLE_DTLS */
{
/* Extract the count of algorithms from the incoming data. */
sign_algs_length = (UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]);
length = length + 2;
/* Make sure what we extracted makes sense. */
if ((length + sign_algs_length) > message_length)
{
return(NX_SECURE_TLS_INCORRECT_MESSAGE_LENGTH);
}
/* Extract the signature algorithms. */
sign_alg = NX_SECURE_TLS_HASH_ALGORITHM_NONE;
for (i = 0; i < sign_algs_length; i += 2)
{
/* Look for a type we support. */
if ((UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]) == expected_sign_alg)
{
sign_alg = (UINT)((packet_buffer[length] << 8) + packet_buffer[length + 1]);
break;
}
length = length + 2;
}
/* Make sure we are using the right signature algorithm! */
if (sign_alg != expected_sign_alg)
{
return(NX_SECURE_TLS_UNSUPPORTED_CERT_SIGN_ALG);
}
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
if (tls_session -> nx_secure_tls_1_3)
{
tls_session -> nx_secure_tls_signature_algorithm = sign_alg;
}
#endif
}
#endif
/* The remainder of the message is the Certificate Authorities list. It can be used
to select a certificate in a particular authorization chain. In general, if there
is only one device certificate we will send that one and if the server doesn't like
it the connection will be dropped. */
#ifdef NX_SECURE_TLS_CLIENT_DISABLED
/* If TLS Client is disabled and we have processed a CertificateRequest, something is wrong... */
tls_session -> nx_secure_tls_server_state = NX_SECURE_TLS_SERVER_STATE_ERROR;
return(NX_SECURE_TLS_INVALID_STATE);
#else
/* Set our state to indicate we received a certificate request. */
tls_session -> nx_secure_tls_client_state = NX_SECURE_TLS_CLIENT_STATE_CERTIFICATE_REQUEST;
return(NX_SUCCESS);
#endif
}
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