Hardware support for trusted execution in modern CPUs enables tenants to shield their data processing workloads in otherwise untrusted cloud environments. Runtime systems for the trusted execution must rely on an interface to the untrusted host OS to use external resources such as storage, network, and other functions. Attackers may exploit this interface to leak data or corrupt the computation.We describe SGX-LKL, a system for running Linux binaries inside of Intel SGX enclaves that only exposes a minimal, protected and oblivious host interface: the interface is (i) minimal because SGX-LKL uses a complete library OS inside the enclave, including file system and network stacks, which requires a host interface with only 7 calls; (ii) protected because SGX-LKL transparently encrypts and integrity-protects all data passed via low-level I/O operations; and (iii) oblivious because SGX-LKL performs host operations independently of the application workload. For oblivious disk I/O, SGX-LKL uses an encrypted ext4 file system with shuffled disk blocks. We show that SGX-LKL protects TensorFlow training with a 21% overhead.

Library OSs have been proposed to deploy applications isolated inside containers, VMs, or trusted execution environments. They often follow a highly modular design in which third-party components are combined to offer the OS functionality needed by an application, and they are customised at compilation and deployment time to fit application requirements. Yet their monolithic design lacks isolation across components: when applications and OS components contain security-sensitive data (e.g., cryptographic keys or user data), the lack of isolation renders library OSs open to security breaches via malicious or vulnerable third-party components.We describe CubicleOS, a library OS that isolates components in the system while maintaining the simple, monolithic development approach of library composition. CubicleOS allows isolated components, called cubicles, to share data dynamically with other components. It provides spatial memory isolation at the granularity of function calls by using Intel MPK at user-level to isolate components. At the same time, it supports zero-copy data access across cubicles with feature-rich OS functionality. Our evaluation shows that CubicleOS introduces moderate end-to-end performance overheads in complex applications: 2× for the I/O-intensive NGINX web server with 8 partitions, and 1.7-8× for the SQLite database engine with 7 partitions. CCS CONCEPTS• Software and its engineering → Message passing; • Security and privacy → Operating systems security; Software and application security.

Trusted execution environments (TEEs) give a cost-e ective, "lift-and-shift" solution for deploying security-sensitive applications in untrusted clouds. For this, they must support rich, multi-component applications, risking a large trusted computing base inside the TEE. Fine-grained compartmentalisation can increase security through defense-in-depth, but current solutions either run all software components unprotected in the same TEE, lack e cient shared memory support, or isolate application processes using separate TEEs, impacting performance and compatibility.We describe the Spons & Shields framework (SSF) for Intel SGX TEEs. Spons and Shields are new abstractions that generalise process, library and user/kernel isolation inside the TEE while allowing for e cient memory sharing. For unmodi ed multi-component applications in a TEE, SSF dynamically creates Spons (one per POSIX process or library) and Shields (to enforce a memory access policy). Applications can be hardened easily, e.g., by using a separate Shield to isolate an SSL library. SSF uses compiler instrumentation to protect Shield boundaries, exploiting MPX instructions if available. We evaluate SSF using a complex application service (NGINX, PHP interpreter and PostgreSQL) and show that its overhead is comparable to process isolation.

Abstract-Power outages and subsequent recovery are major causes of service downtimes. This issue is amplified by the ongoing trend of steadily growing in-memory state of Internetbased services which increases the risk of data loss and extends recovery time. Protective measures against power outages, such as uninterruptible power supply are expensive, maintenanceintensive and often fragile. With the advent of non-volatile random-access memory (NVRAM) provided by commodity servers, there is a scalable, less costly and robust alternative to recover from power outages and other failures. However, as of today, off-the-shelf software is not ready for benefiting from NVRAM.We present NV-Hypervisor a lightweight hypervisor extension that transparently provides persistence for virtual machines. NV-Hypervisor paves the way for utilizing NVRAM in virtualized environments (i.e., infrastructure-as-a-service clouds) and protects stateful services such as key-value stores and databases from data loss and time-consuming recovery.

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