Lightweight virtual machines (VMs) are prominently adopted for improved performance and dependability in cloud environments. To reduce boot up times and resource utilisation, they are usually "pre-baked" with only the minimal kernel and userland strictly required to run an application. This introduces a fundamental trade-off between the advantages of lightweight VMs and available services within a VM, usually leaning towards the former. We propose VMSH, a hypervisor-agnostic abstraction that enables on-demand attachment of services to a running VM---allowing developers to provide minimal, lightweight images without compromising their functionality. The additional applications are made available to the guest via a file system image. To ensure that the newly added services do not affect the original applications in the VM, VMSH uses lightweight isolation mechanisms based on containers. We evaluate VMSH on multiple KVM-based hypervisors and Linux LTS kernels and show that: (i) VMSH adds no overhead for the applications running in the VM, (ii) de-bloating images from the Docker registry can save up to 60% of their size on average, and (iii) VMSH enables cloud providers to offer services to customers, such as recovery shells, without interfering with their VM's execution.

Computation Storage Architectures (CSA) are increasingly adopted in the cloud for near data processing, where the underlying storage devices/servers are now equipped with heterogeneous cores which enable computation offloading near to the data. While CSA is a promising high-performance architecture for the cloud, in general data analytics also presents significant data security and policy compliance (e.g., GDPR) challenges in untrusted cloud environments. In this paper, we present IronSafe, a secure and policy-compliant query processing system for heterogeneous computational storage architectures, while preserving the performance advantages of CSA in untrusted cloud environments. To achieve these design properties in a computing environment with heterogeneous host (x86) and storage system (ARM), we design and implement the entire hardware and software system stack from the ground-up leveraging hardware-assisted Trusted Execution Environments (TEEs): namely, Intel SGX and ARM TrustZone. More specifically, IronSafe builds on three core contributions: (1) a heterogeneous confidential computing framework for shielded execution with x86 and ARM TEEs and associated secure storage system for the untrusted storage medium; (2) a policy compliance monitor to provide a unified service for attestation and policy compliance; and (3) a declarative policy language and associated interpreter for concisely specifying and efficiently evaluating a rich set of polices. Our evaluation using the TPC-H SQL benchmark queries and GDPR anti-pattern use-cases shows that IronSafe is faster, on average by 2.3x than a host-only secure system, while providing strong security and policy-compliance properties.

The shielding of applications using trusted execution environments (TEEs) can provide strong security guarantees in untrusted cloud environments. When executing I/O operations, today's shielded execution frameworks, however, exhibit performance and security limitations: they assign resources to the I/O path inefficiently, perform redundant data copies, use untrusted host I/O stacks with security risks and performance overheads. This prevents TEEs from running modern I/O-intensive applications that require high-performance networking and storage.