That wasn't a fork, it was a research project, and the resulting patches were integrated into mainline linux back in 2.6 It was run by the University of Utah a

That wasn't a fork, it was a research project, and the resulting patches were integrated into mainline linux back in 2.6 It was run by the University of Utah and the NSA but eventually involving several contractors to implement the FLASK architecture as prototyped in the Fluke research OS as patches against Linux. Met and worked with some people who handled the user-space tools and patches, interesting stuff. The goal was to enhance Linux beyond discretionary access control (DAC) to mandatory access control (MAC) which would put Linux a step above WinNT and in the same boat as Trusted Solaris, so you could properly implement a Bell–LaPadula security model (write up, no write down) They succeeded and so now you have stuff like General Dynamic's PitBull cross domain solution which builds on and extends it. That was really what NSA wanted out of it in the end, since they have the responsibility to provide and approve such systems, which are very in demand in DoD and govt. AppArmor uses the same framework in the kernel that SELinux uses, but the policy implementation is different. The competing needs of AppArmor, LIDS, and SELinux are what prompted LSM to be created in the first place. But that research also has applicability in the space of trust segmentation, providing similar capabilities to containers and sandboxes but before they popularly existed. SELinux still performs this policy enforcement function for many distros' container security implementations, in addition to seccomp.