Security-Preserving Live Migration of Virtual Machines in the Cloud

摘要

Hypervisor-based process protection is a novel approach that provides isolated execution environments for applications running on untrusted commodity operating systems. It is based on off-the-shelf hardware and trusted hypervisors while it meets the requirement of security and trust for many cloud computing models, especially third-party data centers and a multi-tenant public cloud, in which sensitive data are out of the control of the users. However, as the hypervisor extends semantic protection to the process granularity, such a mechanism also breaks the platform independency of virtual machines and thus prohibits live migration of virtual machines, which is another highly desirable feature in the cloud. In this paper, we extend hypervisor-based process protection systems with live migration capabilities by migrating the protection-related metadata maintained in the hypervisor together with virtual machines and protecting sensitive user contents using encryption and hashing. We also propose a security-preserving live migration protocol that addresses several security threats during live migration procedures including timing-related attacks, replay attacks and resumption order attacks. We implement a prototype system base on Xen and Linux. Evaluation results show that performance degradation in terms of both total migration time and downtime are reasonably low compared to the unmodified Xen live migration system.