TLS1.3: Add Encrypted Extensions
Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 979db31..686edfe 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -1395,11 +1395,125 @@
}
/*
- * Handler for MBEDTLS_SSL_ENCRYPTED_EXTENSIONS
+ *
+ * EncryptedExtensions message
+ *
+ * The EncryptedExtensions message contains any extensions which
+ * should be protected, i.e., any which are not needed to establish
+ * the cryptographic context.
*/
-static int ssl_tls1_3_process_encrypted_extensions( mbedtls_ssl_context *ssl )
+
+/*
+ * Overview
+ */
+static int ssl_tls1_3_read_encrypted_extensions( mbedtls_ssl_context *ssl );
+
+/* Main entry point; orchestrates the other functions */
+static int ssl_tls13_encrypted_extensions_process( mbedtls_ssl_context *ssl );
+
+static int ssl_tls13_encrypted_extensions_parse( mbedtls_ssl_context *ssl,
+ const unsigned char *buf,
+ size_t buf_len );
+static int ssl_tls13_encrypted_extensions_postprocess( mbedtls_ssl_context *ssl );
+
+/*
+ * Handler for MBEDTLS_SSL_ENCRYPTED_ENTENSIONS
+ */
+static int ssl_tls13_encrypted_extensions_process( mbedtls_ssl_context *ssl )
{
- MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) );
+ int ret;
+ unsigned char *buf;
+ size_t buf_len;
+
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse encrypted extensions" ) );
+
+ MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_tls13_fetch_handshake_msg( ssl,
+ MBEDTLS_SSL_HS_ENCRYPTED_EXTENSION,
+ &buf, &buf_len ) );
+
+ /* Process the message contents */
+ MBEDTLS_SSL_PROC_CHK( ssl_tls13_encrypted_extensions_parse( ssl, buf, buf_len ) );
+
+ mbedtls_ssl_tls13_add_hs_msg_to_checksum(
+ ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSION, buf, buf_len );
+
+ MBEDTLS_SSL_PROC_CHK( ssl_tls13_encrypted_extensions_postprocess( ssl ) );
+
+cleanup:
+
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse encrypted extensions" ) );
+ return( ret );
+
+}
+
+static int ssl_tls13_encrypted_extensions_parse( mbedtls_ssl_context *ssl,
+ const unsigned char *buf,
+ size_t buf_len )
+{
+ int ret = 0;
+ size_t ext_len;
+ const unsigned char *ext;
+
+ if( buf_len < 2 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "EncryptedExtension message too short" ) );
+ return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+ }
+
+ ext_len = MBEDTLS_GET_UINT16_BE(buf, 0);
+
+ buf += 2; /* skip extension length */
+ ext = buf;
+
+ /* Checking for an extension length that is too short */
+ if( ext_len > 0 && ext_len < 4 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "EncryptedExtension message too short" ) );
+ return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+ }
+
+ /* Checking for an extension length that isn't aligned with the rest
+ * of the message */
+ if( buf_len != 2 + ext_len )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "EncryptedExtension lengths misaligned" ) );
+ return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+ }
+
+ MBEDTLS_SSL_DEBUG_BUF( 3, "encrypted extensions extensions", ext, ext_len );
+
+ while( ext_len )
+ {
+ unsigned int ext_id = MBEDTLS_GET_UINT16_BE(ext, 0);
+ size_t ext_size = MBEDTLS_GET_UINT16_BE(ext, 2);
+
+ if( ext_size + 4 > ext_len )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad encrypted extensions message" ) );
+ return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+ }
+
+ /* TBD: The client MUST check EncryptedExtensions for the
+ * presence of any forbidden extensions and if any are found MUST abort
+ * the handshake with an "illegal_parameter" alert.
+ */
+ ((void) ext_id);
+
+ ext_len -= 4 + ext_size;
+ ext += 4 + ext_size;
+
+ if( ext_len > 0 && ext_len < 4 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad encrypted extensions message" ) );
+ return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+ }
+ }
+
+ return( ret );
+}
+
+static int ssl_tls13_encrypted_extensions_postprocess( mbedtls_ssl_context *ssl )
+{
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_CERTIFICATE_REQUEST );
return( 0 );
}
@@ -1555,6 +1669,10 @@
ret = ssl_tls1_3_handshake_wrapup( ssl );
break;
+ case MBEDTLS_SSL_ENCRYPTED_EXTENSIONS:
+ ret = ssl_tls13_encrypted_extensions_process( ssl );
+ break;
+
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );