Linux Security Modules: General Security Support for the Linux Kernel

The access control mechanisms of existing mainstream operating systems are inadequate to provide strong system security. Enhanced access control mechanisms have failed to win acceptance into mainstream operating systems due in part to a lack of consensus within the security community on the right solution. Since general-purpose operating systems must satisfy a wide range of user requirements, any access control mechanism integrated into such a system must be capable of supporting many different access control models. The Linux Security Modules (LSM) project has developed a lightweight, general purpose, access control framework for the mainstream Linux kernel that enables many different access control models to be implemented as loadable kernel modules. A number of existing enhanced access control implementations, including Linux capabilities, Security-Enhanced Linux (SELinux), and Domain and Type Enforcement (DTE), have already been adapted to use the LSM framework. This paper presents the design and implementation of LSM and discusses the challenges in providing a truly general solution that minimally impacts the Linux kernel.