Much of the actual work in the implementation of SELinux was done by Secure Computing Corporation (SCC). SCC, in its implementation of SELinux, used a technology that it calls type enforcement. As it turns out, SCC has a patent on this technology.
... At that time, SCC put up an SELinux FAQ stating: ...
There will be no restrictions on the use of TE by the Linux open source community....
... Recently, this page has been removed from the SCC web site - a move which should be of concern to anybody who is relying on web-based promises about access to patented technology.
... So, SCC may eventually do the right thing (from the free software community's point of view) and preserve the free licensing of SELinux. ... Either way, this situation shows, yet another time, the sort of threat that software patents pose to free software.