Research Of Method To System Flexibility Response Based On Embedded System

With more and more widely used, Embedded Systems become large and complex, resulting that reliability and security of the system is getting worse. How to maintain a certain performance and continued safe operation when Embedded System is infringed is a very important area of Embedded System research. Therefore, Embedded System Flexibility Response mechanism appears. The current research on Embedded System security often considers from the perspective of static preventing, lack of the design consideration for dynamic security strategies, thus can not dynamically get security situation of running system and respond. Meanwhile, the adaptability to Embedded System hardware configuration changes is weak. To solve these problems, the idea of the Flexibility Response is proposed in this paper. Research is carried out in the following areas:The research situation of Embedded System security is analyzed. The Embedded Operating System security, process safety, system scheduling and other aspects are described and reviewed. Ways of Flexibility Response are explored. The technique that is Embedded Operating System security architecture, checkpoint technique and Embedded Operating System scheduling is introduced, which can enhance security and reliability of Embedded System.The Flexibility Response theory and related methods are in-depth studied, and the Flexibility Response mechanism is defined. The security enhancement method of the Embedded Operating System architecture, Embedded System security vulnerabilities and virtual file system are introduced. It is detailedly analyzed that technology to achieve Flexibility Response mechanism which includes security framework of the Flask, SELinux security mechanism, vulnerabilities detecting and evaluation and dynamic strategies configuration. Based on SELinux security mechanism, the Embedded Operating System Flexibility Response architecture is proposed, and the methods of security situation dynamic evaluation and dynamic strategies configuration are discussed, so as to enhance the Flexibility Response capability of Embedded System in terms of system architecture.To deal with the problem that Embedded System can not dynamically get security situation and respond when system is running, the assessment methods of security level based on vulnerability feature is proposed, which achieve dynamic real-time evaluation of system security and provide a decision support for the system dynamic configuration of security strategies and dynamic setting checkpoint interval. Methods of the risk assessment of the combination of vulnerabilities and the vulnerabilities feature vector classification that achieve security assessment are expounded. Issues which include the problem of the least vulnerabilities combination, the problem of best number of classification for vulnerabilities feature vectors and the problem of vulnerabilities harm assessment updating are discussed.Based on assessment of the security level, to improve the system fault-tolerant capability, robustness, stability and recoverability, Flexibility Response method for process based on the dynamic checkpoint intervals is proposed. Backup and recovery of the system process is realized by the application of checkpoint mechanism. In order to realize the dynamic adjustment of checkpoint interval, the "J.T. Daly model" that calculate the optimal static checkpoint interval is improved. Based on this model, a new approach for dynamically setting the checkpoint interval is proposed. Compared with static checkpoint interval setting, the dynamic checkpoint interval setting approach reduced the checkpoint overhead rates and improved Flexibility Response capacity of the system.To cope with problems of system task scheduling exception in the running Embedded System caused by system hardware configuration changes, the causes of system scheduling exception are analyzed, and the Flexibility Response method to deal with system task scheduling exception of Embedded System is proposed. The formal description on scheduling exception and definition of the scheduling stability are given. Based on scheduling stability, two scheduling rules SAR and DX are proposed, which enhance the adaptability of the Embedded Operating System to the hardware configuration changes and improve the scheduling stability, effectively preventing scheduling exception brought by the system hardware configuration changes.