  Mobile devices are in roles where the integrity and confidentiality of their
apps and data are of paramount importance. They usually contain a
System-on-Chip (SoC), which integrates microprocessors and peripheral
Intellectual Property (IP) connected by a Network-on-Chip (NoC). Malicious IP
or software could compromise critical data. Some types of attacks can be
blocked by controlling data transfers on the NoC using Memory Management Units
(MMUs) and other access control mechanisms. However, commodity processors do
not provide strong assurances regarding the correctness of such mechanisms, and
it is challenging to verify that all access control mechanisms in the system
are correctly configured. We propose a NoC Firewall (NoCF) that provides a
single locus of control and is amenable to formal analysis. We demonstrate an
initial analysis of its ability to resist malformed NoC commands, which we
believe is the first effort to detect vulnerabilities that arise from NoC
protocol violations perpetrated by erroneous or malicious IP.
