/**
* Parse OCSP certificate ID
*
* @v ocsp OCSP check
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int ocsp_parse_cert_id ( struct ocsp_check *ocsp,
const struct asn1_cursor *raw ) {
struct asn1_cursor cursor;
struct asn1_algorithm *algorithm;
int rc;
/* Check certID algorithm */
memcpy ( &cursor, raw, sizeof ( cursor ) );
asn1_enter ( &cursor, ASN1_SEQUENCE );
if ( ( rc = asn1_digest_algorithm ( &cursor, &algorithm ) ) != 0 ) {
DBGC ( ocsp, "OCSP %p \"%s\" certID unknown algorithm: %s\n",
ocsp, x509_name ( ocsp->cert ), strerror ( rc ) );
return rc;
}
if ( algorithm->digest != &ocsp_digest_algorithm ) {
DBGC ( ocsp, "OCSP %p \"%s\" certID wrong algorithm %s\n",
ocsp, x509_name ( ocsp->cert ),
algorithm->digest->name );
return -EACCES_CERT_MISMATCH;
}
/* Check remaining certID fields */
asn1_skip ( &cursor, ASN1_SEQUENCE );
if ( asn1_compare ( &cursor, &ocsp->request.cert_id_tail ) != 0 ) {
DBGC ( ocsp, "OCSP %p \"%s\" certID mismatch:\n",
ocsp, x509_name ( ocsp->cert ) );
DBGC_HDA ( ocsp, 0, ocsp->request.cert_id_tail.data,
ocsp->request.cert_id_tail.len );
DBGC_HDA ( ocsp, 0, cursor.data, cursor.len );
return -EACCES_CERT_MISMATCH;
}
return 0;
}
/**
* Build OCSP request
*
* @v ocsp OCSP check
* @ret rc Return status code
*/
static int ocsp_request ( struct ocsp_check *ocsp ) {
struct digest_algorithm *digest = &ocsp_digest_algorithm;
struct asn1_builder *builder = &ocsp->request.builder;
struct asn1_cursor *cert_id_tail = &ocsp->request.cert_id_tail;
uint8_t digest_ctx[digest->ctxsize];
uint8_t name_digest[digest->digestsize];
uint8_t pubkey_digest[digest->digestsize];
int rc;
/* Generate digests */
digest_init ( digest, digest_ctx );
digest_update ( digest, digest_ctx, ocsp->cert->issuer.raw.data,
ocsp->cert->issuer.raw.len );
digest_final ( digest, digest_ctx, name_digest );
digest_init ( digest, digest_ctx );
digest_update ( digest, digest_ctx,
ocsp->issuer->subject.public_key.raw_bits.data,
ocsp->issuer->subject.public_key.raw_bits.len );
digest_final ( digest, digest_ctx, pubkey_digest );
/* Construct request */
if ( ( rc = ( asn1_prepend_raw ( builder, ocsp->cert->serial.raw.data,
ocsp->cert->serial.raw.len ),
asn1_prepend ( builder, ASN1_OCTET_STRING,
pubkey_digest, sizeof ( pubkey_digest ) ),
asn1_prepend ( builder, ASN1_OCTET_STRING,
name_digest, sizeof ( name_digest ) ),
asn1_prepend ( builder, ASN1_SEQUENCE,
ocsp_algorithm_id,
sizeof ( ocsp_algorithm_id ) ),
asn1_wrap ( builder, ASN1_SEQUENCE ),
asn1_wrap ( builder, ASN1_SEQUENCE ),
asn1_wrap ( builder, ASN1_SEQUENCE ),
asn1_wrap ( builder, ASN1_SEQUENCE ),
asn1_wrap ( builder, ASN1_SEQUENCE ) ) ) != 0 ) {
DBGC ( ocsp, "OCSP %p \"%s\" could not build request: %s\n",
ocsp, x509_name ( ocsp->cert ), strerror ( rc ) );
return rc;
}
DBGC2 ( ocsp, "OCSP %p \"%s\" request is:\n",
ocsp, x509_name ( ocsp->cert ) );
DBGC2_HDA ( ocsp, 0, builder->data, builder->len );
/* Parse certificate ID for comparison with response */
cert_id_tail->data = builder->data;
cert_id_tail->len = builder->len;
if ( ( rc = ( asn1_enter ( cert_id_tail, ASN1_SEQUENCE ),
asn1_enter ( cert_id_tail, ASN1_SEQUENCE ),
asn1_enter ( cert_id_tail, ASN1_SEQUENCE ),
asn1_enter ( cert_id_tail, ASN1_SEQUENCE ),
asn1_enter ( cert_id_tail, ASN1_SEQUENCE ),
asn1_skip ( cert_id_tail, ASN1_SEQUENCE ) ) ) != 0 ) {
DBGC ( ocsp, "OCSP %p \"%s\" could not locate certID: %s\n",
ocsp, x509_name ( ocsp->cert ), strerror ( rc ) );
return rc;
}
return 0;
}
/**
* Identify X.509 certificate public key
*
* @v certificate Certificate
* @v algorithm Public key algorithm to fill in
* @v pubkey Public key value to fill in
* @ret rc Return status code
*/
static int x509_public_key ( const struct asn1_cursor *certificate,
struct asn1_cursor *algorithm,
struct asn1_cursor *pubkey ) {
struct asn1_cursor cursor;
int rc;
/* Locate subjectPublicKeyInfo */
memcpy ( &cursor, certificate, sizeof ( cursor ) );
rc = ( asn1_enter ( &cursor, ASN1_SEQUENCE ), /* Certificate */
asn1_enter ( &cursor, ASN1_SEQUENCE ), /* tbsCertificate */
asn1_skip_if_exists ( &cursor, ASN1_EXPLICIT_TAG ), /* version */
asn1_skip ( &cursor, ASN1_INTEGER ), /* serialNumber */
asn1_skip ( &cursor, ASN1_SEQUENCE ), /* signature */
asn1_skip ( &cursor, ASN1_SEQUENCE ), /* issuer */
asn1_skip ( &cursor, ASN1_SEQUENCE ), /* validity */
asn1_skip ( &cursor, ASN1_SEQUENCE ), /* name */
asn1_enter ( &cursor, ASN1_SEQUENCE )/* subjectPublicKeyInfo*/);
if ( rc != 0 ) {
DBG ( "Cannot locate subjectPublicKeyInfo in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return rc;
}
/* Locate algorithm */
memcpy ( algorithm, &cursor, sizeof ( *algorithm ) );
rc = ( asn1_enter ( algorithm, ASN1_SEQUENCE ) /* algorithm */ );
if ( rc != 0 ) {
DBG ( "Cannot locate algorithm in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return rc;
}
/* Locate subjectPublicKey */
memcpy ( pubkey, &cursor, sizeof ( *pubkey ) );
rc = ( asn1_skip ( pubkey, ASN1_SEQUENCE ), /* algorithm */
asn1_enter ( pubkey, ASN1_BIT_STRING ) /* subjectPublicKey*/ );
if ( rc != 0 ) {
DBG ( "Cannot locate subjectPublicKey in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return rc;
}
return 0;
}
/**
* Identify X.509 certificate RSA modulus and public exponent
*
* @v certificate Certificate
* @v rsa RSA public key to fill in
* @ret rc Return status code
*
* The caller is responsible for eventually calling
* x509_free_rsa_public_key() to free the storage allocated to hold
* the RSA modulus and exponent.
*/
int x509_rsa_public_key ( const struct asn1_cursor *certificate,
struct x509_rsa_public_key *rsa_pubkey ) {
struct asn1_cursor algorithm;
struct asn1_cursor pubkey;
struct asn1_cursor modulus;
struct asn1_cursor exponent;
int rc;
/* First, extract the public key algorithm and key data */
if ( ( rc = x509_public_key ( certificate, &algorithm,
&pubkey ) ) != 0 )
return rc;
/* Check that algorithm is RSA */
rc = ( asn1_enter ( &algorithm, ASN1_OID ) /* algorithm */ );
if ( rc != 0 ) {
DBG ( "Cannot locate algorithm:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return rc;
}
if ( ( algorithm.len != sizeof ( oid_rsa_encryption ) ) ||
( memcmp ( algorithm.data, &oid_rsa_encryption,
sizeof ( oid_rsa_encryption ) ) != 0 ) ) {
DBG ( "algorithm is not rsaEncryption in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return -ENOTSUP;
}
/* Check that public key is a byte string, i.e. that the
* "unused bits" byte contains zero.
*/
if ( ( pubkey.len < 1 ) ||
( ( *( uint8_t * ) pubkey.data ) != 0 ) ) {
DBG ( "subjectPublicKey is not a byte string in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return -ENOTSUP;
}
pubkey.data++;
pubkey.len--;
/* Pick out the modulus and exponent */
rc = ( asn1_enter ( &pubkey, ASN1_SEQUENCE ) /* RSAPublicKey */ );
if ( rc != 0 ) {
DBG ( "Cannot locate RSAPublicKey in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return -ENOTSUP;
}
memcpy ( &modulus, &pubkey, sizeof ( modulus ) );
rc = ( asn1_enter ( &modulus, ASN1_INTEGER ) /* modulus */ );
if ( rc != 0 ) {
DBG ( "Cannot locate modulus in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return -ENOTSUP;
}
if ( modulus.len && ( ! *( ( uint8_t * ) modulus.data ) ) ) {
/* Skip positive sign byte */
modulus.data++;
modulus.len--;
}
memcpy ( &exponent, &pubkey, sizeof ( exponent ) );
rc = ( asn1_skip ( &exponent, ASN1_INTEGER ), /* modulus */
asn1_enter ( &exponent, ASN1_INTEGER ) /* publicExponent */ );
if ( rc != 0 ) {
DBG ( "Cannot locate publicExponent in:\n" );
DBG_HDA ( 0, certificate->data, certificate->len );
return -ENOTSUP;
}
if ( exponent.len && ( ! *( ( uint8_t * ) exponent.data ) ) ) {
/* Skip positive sign byte */
exponent.data++;
exponent.len--;
}
/* Allocate space and copy out modulus and exponent */
rsa_pubkey->modulus = malloc ( modulus.len + exponent.len );
if ( ! rsa_pubkey->modulus )
return -ENOMEM;
rsa_pubkey->exponent = ( rsa_pubkey->modulus + modulus.len );
memcpy ( rsa_pubkey->modulus, modulus.data, modulus.len );
rsa_pubkey->modulus_len = modulus.len;
memcpy ( rsa_pubkey->exponent, exponent.data, exponent.len );
rsa_pubkey->exponent_len = exponent.len;
DBG2 ( "RSA modulus:\n" );
DBG2_HDA ( 0, rsa_pubkey->modulus, rsa_pubkey->modulus_len );
DBG2 ( "RSA exponent:\n" );
DBG2_HDA ( 0, rsa_pubkey->exponent, rsa_pubkey->exponent_len );
return 0;
}