【作者】 马祥顺；

【导师】 赵跃华；

【作者基本信息】 江苏大学 ， 计算机应用技术， 2008， 硕士

【摘要】 嵌入式系统在电力领域有着广泛的应用基础。随着电力系统规模的扩大和自动化水平的提高,电力系统对底层设备的可靠性、安全性要求越来越高。但是由于嵌入式系统本身条件的限制,嵌入式操作系统的安全防护能力有限,系统的信息安全面临极大的挑战。在嵌入式操作系统领域,安全开发正处于一个起步阶段,国内外目前的嵌入式操作系统主要考虑的是它的实时性和稳定性,没有对安全性做出太多的考虑,这显然不能满足电力领域越来越紧迫的安全性需求。论文以电力系统中的子站系统为设计对象,设计一个适用于电力领域的安全嵌入式操作系统,以保证系统的信息安全。设计采用微内核模型和分层模型相结合的体系结构,使目标系统同时具有了模块化和可靠的特点,尽量做到对原内核改动的最小化,以满足电力控制领域对实时性和稳定性的要求。在对系统访问控制的形式化设计中,研究分析了各类安全策略模型,着重考虑了安全模型在嵌入式应用的特殊性,最终基于BLP(Bell-La-Padula),全新设计了应用于嵌入式领域的安全访问控制模型μBLP,并采用了Z语言对新模型进行了规范化的描述,旨在今后的工作中能对模型的正确性作进一步的证明,以符合高安全级别的标准。论文采用μC/OS-Ⅱ作为内核开发原型。在提出了系统框架的基础上,完成了整体设计。作为操作系统的核心,内核成为设计的重点,在其实现方案中,考虑到应用安全访问控制对稳定性以及实时性的影响,论文结合电力系统的需求引入了决策缓冲机制。具体设计将安全内核划分为访问监视器,策略缓存,仲裁服务器,以及审计系统各个子模块,并对它们予以详细地实现。在实现了安全内核的基础上,本文在最后对系统的各个子系统进行了分析与设计,特别地给出了内核扩展层与内存管理模块的关系。在测试环节,根据预先设计的安全策略,搭建测试平台,制定测试方案进行了具体测试,根据测试结果,对内核系统的性能指标做出量化分析。测试结果表明,在所设计的系统中,对内核客体的访问控制符合所制定的安全策略,并且整个内核运行稳定,实时性的负面影响不超过原有系统性能指标的10%。更多还原

【Abstract】 Embedded systems have a broad application base in field of power,as the expansion of the scale and the improvement of automation,power system has increasing demands for reliability,security of substation monitoring and protection system.However,due to the conditions of embedded systems own,their security capacities are limited,and information security systems face enormous challenges. Security operating system development is at a preliminary stage in embedded operating system area.Embedded operating systems at home and abroad presently pay major attantions to their real-time and stability,and don’t make many considerations to security,which can not meet the more pressing security requriment of system obviously.Paper chooses sub-station system of power as the design object.Construct a secure embedded system applied to power field,which assure safety of the system information.System design use the architecture combing micro-core model and hierarchical model,brought the target system with modular and reliable characteristics,it make the smallest changes to the original core as possible to meet the electricity system requirements of real-time control and stability.In formal design of access control,paper research and analysis various security strategy models,focus on the particularity of secure models applications on the embedded system.Finally based on the BLP,redesign a new secure model namedμBLP,which is suitable to embedded system,and use Z language to standardize the description of the model,to proof it’s correctness in further work.The formal design is to meet the higher level of security standards.Paper choosesμC/OS-Ⅱas development prototype.Based on the framework of system,accomplish design of the system overall.As the core of operating system,is the focus of whole design,in its implementation of access control,taking into account the impact of real-time and stability when apply secure strategy,paper introduce a buffer decision-making mechanism.Concrete implement divide secure kernel into some parts,security monitors,strategy cache,arbitration server,and audit module,these sub-modules are coded detailedly.Based on the secure kernel,finally analysis and design the subsystems,including file system and network system,give module relations of the expansion level and memory management specially.In the test phrase,build the test platform,according to the pre-designed security strategy,develop test solutions,and get the target system performance indicators to make quantitative analysis according test results.Test results show that the access to objects in kernel is according with the security policies pre-developed,secure kernel run stable,and the negative effect on real-time system performance does not exceed the original target of 10%.更多还原