Have You Driven an SELinux Lately? An Update on the Security Enhanced Linux Project James Morris Red Hat Asia Pacific Pte Ltd
[email protected] Abstract All security-relevant accesses between subjects and ob- jects are controlled according to a dynamically loaded Security Enhanced Linux (SELinux) [18] has evolved mandatory security policy. Clean separation of mecha- rapidly over the last few years, with many enhancements nism and policy provides considerable flexibility in the made to both its core technology and higher-level tools. implementation of security goals for the system, while fine granularity of control ensures complete mediation. Following integration into several Linux distributions, SELinux has become the first widely used Mandatory An arbitrary number of different security models may be Access Control (MAC) scheme. It has helped Linux to composed (or “stacked”) by SELinux, with their com- receive the highest security certification likely possible bined effect being fully analyzable under a unified pol- for a mainstream off the shelf operating system. icy scheme. SELinux has also proven its worth for general purpose Currently, the default SELinux implementation com- use in mitigating several serious security flaws. poses the following security models: Type Enforcement (TE) [7], Role Based Access Control (RBAC) [12], While SELinux has a reputation for being difficult to Muilti-level Security (MLS) [29], and Identity Based use, recent developments have helped significantly in Access Control (IBAC). These complement the standard this area, and user adoption is advancing rapidly. Linux Discretionary Access Control (DAC) scheme. This paper provides an informal update on the project, With these models, SELinux provides comprehensive discussing key developments and challenges, with the mandatory enforcement of least privilege, confidential- aim of helping people to better understand current ity, and integrity.