Study On Analysis Tools For SELinux Security Policy

In today's information society, people's daliy activities are more and more closely associated with computers. At the same time, computer users are frequently plagued by malicious codes and programs including computer viruses, as well as users' intended or unintended operations. In order to deal with these problems, it is a feasible method to enforce access control and to achieve the principle of least privilege. SELinux, which is one of security enhance mechanisms in Linux operating system, can control access between subjects and objects in the system. But security policy configuration is a hard task for SELinux, so users can't be competent for configuration work unless they have professional skills and sufficient experience. Therefore it is rather significant to build an appropriate tool to assist users with the configurations.In this paper, the importance of access control and SELinux is firstly discussed. SELinux security mechanism and policy description language are introduced, and the analysis methods of both access control space and information flow are discussed in detail. Meanwhile, targets for analyzing validity and integrity of security policy are described. Then policy description language is formally analyzed based on improved SELAC model. And formal representations for security policy language and policy analysis goals are generated. After that, the key algorithms for the analysis methods are described, as well as an analysis tool is built using C language based on the formal theories above. Furthermore, an application system called Student-Teacher system is implemented together with its security policy, which is used to test and to verify the analysis tool.Finally, the research work is summarized, and further work directions are pointed out to improve the analysis tool for SELinux security policy.