Ziteng Chen (Southeast University), Menghao Zhang (Beihang University), Jiahao Cao (Tsinghua University & Quan Cheng Laboratory), Xuzheng Chen (Zhejiang University), Qiyang Peng (Beihang University), Shicheng Wang (Unaffiliated), Guanyu Li (Unaffiliated), Mingwei Xu (Quan Cheng Laboratory & Tsinghua University & Southeast University)
RDMA clouds are becoming prevalent, and ACLs are critical to regulate unauthorized network accesses of RDMA applications, services, and tenants. However, the unique QP semantics and high-speed transmission characteristics of RDMA prevent existing ACL expressions and enforcement mechanisms from comprehensively and efficiently governing RDMA traffic in a user-friendly manner. In this paper, we present Janus, a tailored ACL system for RDMA clouds. Janus designs specialized ACL expressions with QP semantics to identify RDMA connections, and provides a high-level policy language for expressing sophisticated ACL intents to govern RDMA traffic. JANUS further leverages DPUs with traffic-aware and architecture-specific optimizations to enforce ACL policies, enabling line-rate RDMA inspection and robust policy updates. We implement an open-source prototype of JANUS with NVIDIA BlueField-3 DPUs. Experiments demonstrate that JANUS provides sufficient expressivity for governing unauthorized RDMA accesses, and achieves line-rate throughput in a 200Gbps real-world RDMA testbed with <5µs latency.