Research And Implementation Of Virtual Execution Environment. Windows Platform

Virtualization is a technology that partitions the underlying physical machine's hardware or software resources and creates some isolated execution environments. Each of this Execution Environment has strong isolation strength and isolates with other Execution Environments. This characteristic makes a basis for the wide usage of this technology, now it plays a more and more important role in the field of Server consolidation,System migration,make full use of system resources,fault recovery,virtual applications. Etc.Virtualization also plays an important part in the field of Debugging and testing unsafe Applications. Virtualization can abstract a real execution environment, with this, any application that runs in this environment feels no different from running in the real environment, and what is more,any operation of the target process can be monitored and thus preventing the host operating system from any malicious damage.The main challenge of virtualization is how to isolate the Virtual Execution Environment from the Host Operating System. Firstly, this thesis summarizes the current research and development condition of virtualization, compares all the popular virtualization technologies together.Based on the analysis of the layered architecture of Windows system, an OS Level Virtual Execution Environment is proposed which has strong isolation strength and fewer resource requirements. The main part of the OSLVEE is called"Virtual Kernel"module, which implements the virtualization of file system, registry resources, inter process communications, Windows kernel Objects, system Demon processes and network system.OSLVEE is accomplished with the following technologies。Firstly,virtual disk and windows file system filter drivers is used to redirect all file requests from OSLVEE to the virtual disk, thus isolate this virtual execute environment from the host system;Secondly,"namespace redirection"is used to hook and redirect user mode library functions and kernel mode system call functions, which provides applications with virtual system services and resources. Thirdly,"the Copy On Time" technology is used to keep data consistency between Host Operating System and the virtual execution environment.It's proved to be effective that the Virtual Execution Environment can isolate itself from host Operating System and plays an excellent role in debugging and testing unsafe applications, what is more, this virtual execution environment can be used to analysis unsafe applications'operations.