Xen Virtual Machine Data Security And Disk Encryption Strategy

In recent years, virtualization technology is developing rapidly. The XEN VMM (Virtual Machine Monitor), an open source project, makes use of para-virtualization technology, which makes the guest OS have higher performance than the full-virtualization VMM. And it has the super privilege to manage and schedule the hardware resources, which improves the security of the guests. All of the advantages make the XEN have a promising future.XEN Virtual Machine adopts the split device driver model to implement the Domain's access to the hardware resources. When the Domain U(Unprivileged Domain) accesses the disk data of its own, it has to hand over the task to the device driver in Domain 0(Privileged Domain). So if the Domain U doesn't allow other Domains to see the data in its disks, the disks must be encrypted. Besides, if Domain 0 sniffs the processes of Domain U's data access, it is very feasible, which will cause the Domain U's data leak to Domain 0.In this paper, the split device driver model has been analyzed in detail, the Encrypting/Decrypting module is designed and implemented in the front end driver of Domain U. The disks attached into Domain U are encrypted fully except the metadata referring to the file system, which makes the Domain 0 mount the disk successfully but can't view the data of files. AES encrypting algorithm has been adopted to encrypt the data that will be written into the shared memory pages between Domain U and Domain 0, which protects the data of Domain U in security. In this way, it not only keeps the data in Domain U's disk safe in static state, which can't be viewed by Domain 0, but also protects the data in the transferring process when Domain U reads or writes its own disks'data.