From the NSA website . . .

As part of its Information Assurance mission, the National Security Agency (NSA) has long been involved with the computer security research community in investigating a wide range of computer security topics including operating system security. Recognizing the critical role of operating system security mechanisms in supporting security at higher levels, researchers from the NSA's Information Assurance Research Group have been investigating an architecture that can provide the necessary security functionality in a manner that can meet the security needs of a wide range of computing environments.

End systems must be able to enforce the separation of information based on confidentiality and integrity requirements to provide system security. Operating system security mechanisms are the foundation for ensuring such separation. Unfortunately, existing mainstream operating systems lack the critical security feature required for enforcing separation: mandatory access control. As a consequence, application security mechanisms are vulnerable to tampering and bypass, and malicious or flawed applications can easily cause failures in system security.

The results of several previous research projects in this area have been incorporated in a security-enhanced Linux system. This version of Linux has a strong, flexible mandatory access control architecture incorporated into the major subsystems of the kernel. The system provides a mechanism to enforce the separation of information based on confidentiality and integrity requirements. This allows threats of tampering and bypassing of application security mechanisms to be addressed and enables the confinement of damage that can be caused by malicious or flawed applications.

Linux was chosen as the platform for this work because its growing success and open development environment provided an opportunity to demonstrate that this functionality can be successful in a mainstream operating system and, at the same time, contribute to the security of a widely used system. Additionally, the integration of these security research results into Linux may encourage additional operating system security research that may lead to additional improvement in system security.

This work is not intended as a complete security solution for Linux. Security-enhanced Linux is not an attempt to correct any flaws that may currently exist in Linux. Instead, it is simply an example of how mandatory access controls that can confine the actions of any process, including a superuser process, can be added into Linux. The focus of this work has not been on system assurance or other security features such as security auditing, although these elements are also important for a secure system.

The security mechanisms implemented in the system provide flexible support for a wide range of security policies. They make it possible to configure the system to meet a wide range of security requirements. The release includes a general-purpose security policy configuration designed to meet a number of security objectives as an example of how this may be done. The flexibility of the system allows the policy to be modified and extended to customize the security policy as required for any given installation.

There is still much work needed to develop a complete security solution. In addition, due to resource limitations, we have not yet been able to evaluate and optimize the performance of the security mechanisms. Currently, we can only support the x86 architecture and have only been able to test it on Red Hat distributions. Nonetheless, we feel we have presented a good starting point to bring valuable security features to Linux. We are looking forward to building upon this work with the Linux community.

Security-enhanced Linux is being released under the same terms and conditions as the original sources. The release includes documentation and source code for both the system and some system utilities that were modified to make use of the new features. Participation with comments, constructive criticism, and/or improvements is welcome.

Download SELinux here

Information on how to obtain a free 3-disk copy of the beta version of SELinux is available from the OSD group.

• Russell Coker's SELinux website (Russell Coker is integrating the SELinux kernel patch into the Debian GNU/Linux distribution.)
• Information Security Security Maillists/selinux/archive

 
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