Concentrated isolation for container networks toward application-aware sandbox tailoring

Containers provide a lightweight and fine-grained isolation for computational resources such as CPUs, memory, storage, and networks, but their weak isolation raises security concerns. As a result, research and development efforts have focused on redesigning truly sandboxed containers with system call intercept and hardware virtualization techniques such as gVisor and Kata Containers. However, such fully integrated sandboxing could overwhelm the lightweight and scalable nature of the containers. In this work, we propose a partially fortified sandboxing mechanism that concentratedly fortifies the network isolation, focusing on the fact that containerized clouds and the applications running on them require different isolation levels in accordance with their unique characteristics. We describe how to efficiently implement the mechanism to fortify network isolation for containers with a para-passthrough hypervisor and report evaluation results with benchmarks and real applications. Our findings demonstrate that this fortified network isolation has good potential to tailor sandboxes for containerized PaaS/FaaS clouds.