Offloading Security Services to the Cloud Infrastructure

Cloud applications rely on a diverse set of security services from application-layer rate-limiting to TCP SYN cookies and application firewalls. Some of these services are implemented at the infrastructure layer, on the host or in the NIC, to filter attacks closer to their source and free CPU cycles for the tenants' applications. Most security services, however, remain difficult to implement at the infrastructure layer because they are closely tied to the applications they protect. In this paper, we propose to allow tenants to offload small filtering programs to the infrastructure. We design a mechanism to ensure fairness in resource consumption among tenants and show that, by carefully probing specific points of the infrastructure, all resource consumption can be accounted for. We prototype our solution over the new high-performance datapath of Linux. Our preliminary experiments show that an offload to the host's CPU can bring a 4-6x performance improvement. In addition, fairness among tenants introduces an overhead of only 14% in the worst case and approximately 3% for realistic applications.