Study On Key Issues Of Covert Channels Analysis Based On Source Codes

In face of the endless and massive information in the informational society, information system has become an indispensable and powerful tool to process information. Information system security is increasingly attracting widespread attentions. As the fundamental support of information system, the security of operating system is the prerequisite to ensure the security of information system. So nowadays, the study on the security of operating system becomes one of the hot research topics in computer field. In the case of operating system, many threats and attacks are covert, and covert channel is one of them. Therefore, accurate and efficient analysis of covert channel is an important part to ensure the security of operating system, but also a basic prerequisite to ensure the security of information system.The paper chooses Linux kernel source codes as the object to do covert channel analysis, analyzes relevant study results of covert channel analysis, and compares grammar information flow analysis method, shared resource matrix method and covert flow tree analysis method. At the same time, we give the general flow of covert channel analysis and dig out some key problems of covert channel analysis. Mainly, in order to achieve accurate location of analysis range, we analyze the Makefile and strengthen the mechanism of pre-processing to obtain all the shared resources which are reflected in the variables mainly and functions betterly, and we optimize the rules of information flow to get the relation of reading and writing between shared resources and functions.At the same time, the paper chooses Linux 2.6.5 kernel source codes as the object to study the algorithm for transitive closure. We select array and cross-linked list to realize it. Moreover, in order to optimize the algorithm details and make it more suitable for covert channel analysis based on operating system source codes, we analyze and compare the algorithm complexity of these two methods.Finally, the paper sums up the problems in the study and gives the reasearch direction in the future.