This thesis researchs the correlative security evaluation criteria and analyses in detail linux kernel at first . linux kernel is improved at four aspects : access control list , capability , system audit , mandatory access control , based on linux kernel 2 . 4 . 4 on tcsec and the security level of linux is enhanced from cl to bl 本论文首先研究了相关的安全评估标准，并对linux内核进行了详细地分析，然后以tcsec为标准，基于linux内核2 . 4 . 4 ，分别从访问控制表、权能、系统审计以及强制访问控制四个方面时linux内核进行了改进，使linux的安个级别从c1级提高到了b1级。
It encapsulates the property within the objects according to the different rules in different domain to ensure the security of object . with the technology of enciyption and digital signature , the signature is given to the acl , secure property by the owner of the object in order to create a complete secure - object 同时针对不同的安全域采用不同的安全策略(规则) ，提出采用访问控制表实现对对象的存取控制，并且将对象的安全属性分装在自身对象中，因而保证了对象的安全。
