Title
MMCap: Towards Fast and Secure IPC using MMU-Accelerated Memory Capabilities

Authors
Niklas	Gollenstede	gollenstede@ibr.cs.tu-bs.de	Germany	Technische Universität Braunschweig
Sören	Tempel	tempel@ibr.cs.tu-bs.de	Germany	Technische Universität Braunschweig		
Lars	Wrenger	wrenger@sra.uni-hannover.de	Germany	Leibniz Universität Hannover		
Daniel	Lohmann	lohmann@sra.uni-hannover.de	Germany	Leibniz Universität Hannover		
Christian	Dietrich	dietrich@ibr.cs.tu-bs.de	Germany	Technische Universität Braunschweig


Abstract
Inter-process communication (IPC) is essential to securely transmit data between isolated processes, especially in highly-compartmentalized systems. However, the established synchronous mechanisms are limited in message size and multi-core scalability; approaches based on shared memory suffer from either high synchronization overheads or time-of-check to time-of-use (TOCTOU) vulnerabilities.

We propose MMCaps, a new OS abstraction for fast and secure zero-copy asynchronous IPC. Conceptually, an MMCap is a globally-unique capability to a buffer in shared memory. Technically, MMCaps are provided by granting/revoking access to dedicated memory pages in the involved address spaces; their invocation is implicitly access-checked by the MMU without any kernel involvement.

Our Linux-based prototype shows that MMCaps thereby outperforms Linux pipes by 63 percent for four inflight messages and up to 221 percent for 64 inflight messages.