Add I/O buffer resizing in handshake init and free
Add a conditional buffer resizing feature. Introduce tests exercising
it in various setups (serialization, renegotiation, mfl manipulations).
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 60ffa61..db2cdb6 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -245,6 +245,29 @@
return( 0 );
}
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+static int resize_buffer( unsigned char **buffer, size_t len_new, size_t *len_old )
+{
+ unsigned char* resized_buffer = mbedtls_calloc( 1, len_new );
+ if( resized_buffer == NULL )
+ return -1;
+
+ /* We want to copy len_new bytes when downsizing the buffer, and
+ * len_old bytes when upsizing, so we choose the smaller of two sizes,
+ * to fit one buffer into another. Size checks, ensuring that no data is
+ * lost, are done outside of this function. */
+ memcpy( resized_buffer, *buffer,
+ ( len_new < *len_old ) ? len_new : *len_old );
+ mbedtls_platform_zeroize( *buffer, *len_old );
+ mbedtls_free( *buffer );
+
+ *buffer = resized_buffer;
+ *len_old = len_new;
+
+ return 0;
+}
+#endif /* MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH */
+
/*
* Key material generation
*/
@@ -3643,6 +3666,43 @@
{
ssl->handshake = mbedtls_calloc( 1, sizeof(mbedtls_ssl_handshake_params) );
}
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+ /* If the buffers are too small - reallocate */
+ {
+ int modified = 0;
+ if( ssl->in_buf_len < MBEDTLS_SSL_IN_BUFFER_LEN )
+ {
+ if( resize_buffer( &ssl->in_buf, MBEDTLS_SSL_IN_BUFFER_LEN,
+ &ssl->in_buf_len ) != 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", MBEDTLS_SSL_IN_BUFFER_LEN ) );
+ modified = 1;
+ }
+ }
+ if( ssl->out_buf_len < MBEDTLS_SSL_OUT_BUFFER_LEN )
+ {
+ if( resize_buffer( &ssl->out_buf, MBEDTLS_SSL_OUT_BUFFER_LEN,
+ &ssl->out_buf_len ) != 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", MBEDTLS_SSL_OUT_BUFFER_LEN ) );
+ modified = 1;
+ }
+ }
+ if( modified )
+ {
+ /* Update pointers here to avoid doing it twice. */
+ mbedtls_ssl_reset_in_out_pointers( ssl );
+ }
+ }
+#endif
/* All pointers should exist and can be directly freed without issue */
if( ssl->handshake == NULL ||
@@ -5818,6 +5878,60 @@
mbedtls_platform_zeroize( handshake,
sizeof( mbedtls_ssl_handshake_params ) );
+
+#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+ /* If the buffers are too big - reallocate. Because of the way Mbed TLS
+ * processes datagrams and the fact that a datagram is allowed to have
+ * several records in it, it is possible that the I/O buffers are not
+ * empty at this stage */
+ {
+ int modified = 0;
+ uint32_t buf_len = mbedtls_ssl_get_input_buflen( ssl );
+ size_t written_in = 0;
+ size_t written_out = 0;
+ if( ssl->in_buf != NULL &&
+ ssl->in_buf_len > buf_len &&
+ ssl->in_left < buf_len )
+ {
+ written_in = ssl->in_msg - ssl->in_buf;
+ if( resize_buffer( &ssl->in_buf, buf_len, &ssl->in_buf_len ) != 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "input buffer resizing failed - out of memory" ) );
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating in_buf to %d", buf_len ) );
+ modified = 1;
+ }
+ }
+
+ buf_len = mbedtls_ssl_get_output_buflen( ssl );
+ if( ssl->out_buf != NULL &&
+ ssl->out_buf_len > mbedtls_ssl_get_output_buflen( ssl ) &&
+ ssl->out_left < buf_len )
+ {
+ written_out = ssl->out_msg - ssl->out_buf;
+ if( resize_buffer( &ssl->out_buf, buf_len, &ssl->out_buf_len ) != 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "output buffer resizing failed - out of memory" ) );
+ }
+ else
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reallocating out_buf to %d", buf_len ) );
+ modified = 1;
+ }
+ }
+ if( modified )
+ {
+ /* Update pointers here to avoid doing it twice. */
+ mbedtls_ssl_reset_in_out_pointers( ssl );
+ /* Fields below might not be properly updated with record
+ * splitting, so they are manually updated here. */
+ ssl->out_msg = ssl->out_buf + written_out;
+ ssl->in_msg = ssl->in_buf + written_in;
+ }
+ }
+#endif
}
void mbedtls_ssl_session_free( mbedtls_ssl_session *session )
@@ -6499,12 +6613,14 @@
{
mbedtls_platform_zeroize( ssl->out_buf, out_buf_len );
mbedtls_free( ssl->out_buf );
+ ssl->out_buf = NULL;
}
if( ssl->in_buf != NULL )
{
mbedtls_platform_zeroize( ssl->in_buf, in_buf_len );
mbedtls_free( ssl->in_buf );
+ ssl->in_buf = NULL;
}
#if defined(MBEDTLS_ZLIB_SUPPORT)