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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 */
/** */
/** X.509 Digital Certificates */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_x509.h"
#ifndef NX_SECURE_X509_DISABLE_CRL
static UINT _nx_secure_x509_crl_parse_entry(const UCHAR *buffer, ULONG length, UINT *bytes_processed,
const UCHAR **serial_number, UINT *serial_number_length);
#endif /* NX_SECURE_X509_DISABLE_CRL */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_x509_crl_revocation_check PORTABLE C */
/* 6.1.8 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function takes a DER-encoded Certificate Revocation List and */
/* searches for a specific certificate in that list. The issuer of the */
/* CRL is validated against a supplied certificate store, the */
/* CRL issuer is validated to be the same as the one for the */
/* certificate being checked, and the serial number of the certificate */
/* in question is used to search the revoked certificates list. */
/* If the issuers match, the signature checks out, and the certificate */
/* is not present in the list, the call is successful. All other cases */
/* cause an error to be returned. */
/* */
/* INPUT */
/* */
/* crl_data Pointer to DER-encoded CRL */
/* crl_length Length of CRL data in buffer */
/* store Certificate store to be used */
/* certificate The certificate being checked */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_secure_x509_certificate_chain_verify */
/* Verify cert against stores */
/* _nx_secure_x509_certificate_revocation_list_parse */
/* Parse revocation list */
/* _nx_secure_x509_crl_parse_entry Parse an entry in crl */
/* _nx_secure_x509_crl_verify Verify revocation list */
/* _nx_secure_x509_distinguished_name_compare */
/* Compare distinguished name */
/* _nx_secure_x509_store_certificate_find */
/* Find a cert in a store */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/* 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 */
/* 04-02-2021 Timothy Stapko Modified comment(s), */
/* removed dependency on TLS, */
/* resulting in version 6.1.6 */
/* 08-02-2021 Timothy Stapko Modified comment(s), */
/* fixed compiler warnings, */
/* resulting in version 6.1.8 */
/* */
/**************************************************************************/
UINT _nx_secure_x509_crl_revocation_check(const UCHAR *crl_data, UINT crl_length,
NX_SECURE_X509_CERTIFICATE_STORE *store,
NX_SECURE_X509_CERT *certificate)
{
#ifndef NX_SECURE_X509_DISABLE_CRL
NX_SECURE_X509_CRL crl;
UINT status;
UINT crl_bytes;
INT compare_value;
UINT bytes_processed;
UINT length;
const UCHAR *current_buffer;
NX_SECURE_X509_CERT *issuer_certificate;
UINT issuer_location;
const UCHAR *serial_number = NX_NULL;
UINT serial_number_length;
NX_SECURE_MEMSET(&crl, 0, sizeof(NX_SECURE_X509_CRL));
/* First, parse the CRL. */
status = _nx_secure_x509_certificate_revocation_list_parse(crl_data, crl_length, &crl_bytes, &crl);
if (status != NX_SECURE_X509_SUCCESS)
{
return(status);
}
/* Check that the issuers match according to process in RFC 5280. */
compare_value = _nx_secure_x509_distinguished_name_compare(&crl.nx_secure_x509_crl_issuer, &certificate -> nx_secure_x509_issuer, NX_SECURE_X509_NAME_ALL_FIELDS);
if (compare_value)
{
/* The issuers did not match, return error. */
return(NX_SECURE_X509_CRL_ISSUER_MISMATCH);
}
/* Now, check the signature of the CRL. */
/* First, get the issuer certificate. If we have a valid store and CRL, the issuer should be available. */
status = _nx_secure_x509_store_certificate_find(store, &crl.nx_secure_x509_crl_issuer, 0, &issuer_certificate, &issuer_location);
if (status != NX_SECURE_X509_SUCCESS)
{
return(status);
}
/* Now, check that the issuer is valid. */
status = _nx_secure_x509_certificate_chain_verify(store, issuer_certificate);
if (status != NX_SECURE_X509_SUCCESS)
{
return(status);
}
/* Now, verify that the CRL itself is OK. */
status = _nx_secure_x509_crl_verify(certificate, &crl, store, issuer_certificate);
if (status != NX_SECURE_X509_SUCCESS)
{
return(status);
}
/* If we get here, then the CRL is OK and is issued by the same CA as the certificate in question.
Finally, we parse the revocation list and see if the serial number of the certificate being
validated is in the CRL revocation list. */
/* Parse and search the revokedCertificates list that we obtained when we parsed the CRL.
* revokedCertificates SEQUENCE OF SEQUENCE
* {
* userCertificate CertificateSerialNumber,
* revocationDate Time,
* crlEntryExtensions Extensions OPTIONAL
* -- if present, version MUST be v2
* } OPTIONAL,
*/
current_buffer = crl.nx_secure_x509_crl_revoked_certs;
length = crl.nx_secure_x509_crl_revoked_certs_length;
/* Loop through all the entries in the sequence. */
while (length > 0)
{
/* Parse an entry in the revokedCertificates list and get back the serial number. */
status = _nx_secure_x509_crl_parse_entry(current_buffer, length, &bytes_processed, &serial_number, &serial_number_length);
if (status != NX_SECURE_X509_SUCCESS)
{
return(status);
}
/* Make sure we don't run past the end of the sequence if one of the entries was too big. */
if (length < bytes_processed)
{
return(NX_SECURE_X509_ASN1_LENGTH_TOO_LONG);
}
/* Compare the serial number we got from the list (if it exists) to the one in our certificate. */
compare_value = NX_SECURE_MEMCMP(serial_number, certificate -> nx_secure_x509_serial_number,
certificate -> nx_secure_x509_serial_number_length);
/* See if we have a match. */
if (compare_value == 0)
{
/* This certificate has been revoked! */
return(NX_SECURE_X509_CRL_CERTIFICATE_REVOKED);
}
/* No match, go to the next one. */
length -= bytes_processed;
current_buffer = current_buffer + bytes_processed;
}
/* If we get here, the CRL was good and the certificate has not been revoked. */
return(NX_SECURE_X509_SUCCESS);
#else /* NX_SECURE_X509_DISABLE_CRL */
NX_CRYPTO_PARAMETER_NOT_USED(crl_data);
NX_CRYPTO_PARAMETER_NOT_USED(crl_length);
NX_CRYPTO_PARAMETER_NOT_USED(store);
NX_CRYPTO_PARAMETER_NOT_USED(certificate);
#ifdef NX_CRYPTO_STANDALONE_ENABLE
return(NX_CRYPTO_FORMAT_NOT_SUPPORTED);
#else
return(NX_NOT_SUPPORTED);
#endif /* NX_CRYPTO_STANDALONE_ENABLE */
#endif /* NX_SECURE_X509_DISABLE_CRL */
}
#ifndef NX_SECURE_X509_DISABLE_CRL
/* Helper function to parse entries in the revokedCertificates list. */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_x509_crl_parse_entry PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function parses an entry in the revokedCertificates list */
/* embedded within an X.509 CRL. Each entry contains the serial number */
/* of a revoked certificate. This serial number is returned so the */
/* caller can compare it to the serial number of the certificate being */
/* checked for revocation. */
/* */
/* INPUT */
/* */
/* buffer Pointer into CRL data */
/* length Length of CRL data */
/* bytes_processed Return bytes parsed */
/* serial_number Return cert serial number */
/* serial_number_length Return serial number length */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_secure_x509_asn1_tlv_block_parse Parse ASN.1 block */
/* */
/* CALLED BY */
/* */
/* _nx_secure_x509_crl_revocation_check Check revocation in crl */
/* */
/* 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 */
/* */
/**************************************************************************/
static UINT _nx_secure_x509_crl_parse_entry(const UCHAR *buffer, ULONG length, UINT *bytes_processed,
const UCHAR **serial_number, UINT *serial_number_length)
{
USHORT tlv_type;
USHORT tlv_type_class;
ULONG tlv_length;
const UCHAR *tlv_data;
const UCHAR *current_buffer;
ULONG header_length;
UINT status;
/* Each entry in the list is a sequence containing the serial number, revocation date, and extensions. */
*bytes_processed = 0;
current_buffer = buffer;
/* First, parse the sequence. */
status = _nx_secure_x509_asn1_tlv_block_parse(current_buffer, &length, &tlv_type, &tlv_type_class, &tlv_length, &tlv_data, &header_length);
/* Make sure we parsed the block alright. */
if (status != 0)
{
return(status);
}
if (tlv_type != NX_SECURE_ASN_TAG_SEQUENCE || tlv_type_class != NX_SECURE_ASN_TAG_CLASS_UNIVERSAL)
{
return(NX_SECURE_X509_UNEXPECTED_ASN1_TAG);
}
*bytes_processed += header_length + tlv_length;
current_buffer = current_buffer + header_length;
length = tlv_length;
/* Next, parse the serial number. */
status = _nx_secure_x509_asn1_tlv_block_parse(tlv_data, &length, &tlv_type, &tlv_type_class, &tlv_length, &tlv_data, &header_length);
/* Make sure we parsed the block alright. */
if (status != 0)
{
return(status);
}
/* The serial number is an ASN.1 Integer. */
if (tlv_type != NX_SECURE_ASN_TAG_INTEGER || tlv_type_class != NX_SECURE_ASN_TAG_CLASS_UNIVERSAL)
{
return(NX_SECURE_X509_UNEXPECTED_ASN1_TAG);
}
/* Save off the serial number in case someone wants it. */
*serial_number = tlv_data;
*serial_number_length = (USHORT)tlv_length;
/* Don't adjust bytes processed since we handled that above. Just adjust buffer. */
current_buffer = current_buffer + (tlv_length + header_length);
/* Parse the "revocationDate" field. */
status = _nx_secure_x509_asn1_tlv_block_parse(current_buffer, &length, &tlv_type, &tlv_type_class, &tlv_length, &tlv_data, &header_length);
/* Make sure we parsed the block alright. */
if (status != 0)
{
return(status);
}
if ((tlv_type != NX_SECURE_ASN_TAG_UTC_TIME && tlv_type != NX_SECURE_ASN_TAG_GENERALIZED_TIME) || tlv_type_class != NX_SECURE_ASN_TAG_CLASS_UNIVERSAL)
{
return(NX_SECURE_X509_UNEXPECTED_ASN1_TAG);
}
/* Extensions are optional. Add here when implemented. */
return(NX_SECURE_X509_SUCCESS);
}
#endif /* NX_SECURE_X509_DISABLE_CRL */