An embodiment of the invention provides an apparatus and method for passing metadata in STREAMS modules. The apparatus and method are configured to perform acts including, allocating a STREAMS message in a kernel space, storing data in the data block in the STREAMS message, allocating a buffer space for metadata associated with the data, storing the metadata of the data in the metadata block in the STREAMS message, passing the metadata among STREAMS modules as a part of the STREAMS message, and performing an operation based upon the metadata.