Add parameter to ssl_read_record() controlling checksum update
Previously, mbedtls_ssl_read_record() always updated the handshake
checksum in case a handshake record was received. While desirable
most of the time, for the CertificateVerify message the checksum
update must only happen after the message has been fully processed,
because the validation requires the handshake digest up to but
excluding the CertificateVerify itself. As a remedy, the bulk
of mbedtls_ssl_read_record() was previously duplicated within
ssl_parse_certificate_verify(), hardening maintenance in case
mbedtls_ssl_read_record() is subject to changes.
This commit adds a boolean parameter to mbedtls_ssl_read_record()
indicating whether the checksum should be updated in case of a
handshake message or not. This allows using it also for
ssl_parse_certificate_verify(), manually updating the checksum
after the message has been processed.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index cc47058..23b066c 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4283,7 +4283,8 @@
* RFC 6347 4.1.2.7) and continue reading until a valid record is found.
*
*/
-int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl )
+int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl,
+ unsigned update_digest )
{
int ret;
@@ -4313,7 +4314,8 @@
return( ret );
}
- if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
+ if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
+ update_digest == 1 )
{
mbedtls_ssl_update_handshake_status( ssl );
}
@@ -4900,7 +4902,7 @@
}
#endif
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
/* mbedtls_ssl_read_record may have sent an alert already. We
let it decide whether to alert. */
@@ -5275,7 +5277,7 @@
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse change cipher spec" ) );
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
@@ -5904,7 +5906,7 @@
ssl->handshake->calc_finished( ssl, buf, ssl->conf->endpoint ^ 1 );
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
@@ -7653,7 +7655,7 @@
ssl_set_timer( ssl, ssl->conf->read_timeout );
}
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
return( 0 );
@@ -7668,7 +7670,7 @@
/*
* OpenSSL sends empty messages to randomize the IV
*/
- if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
+ if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
return( 0 );