Wait, the GCHQ has a GitHub profile where they share a Graph Database engine. Interesting.
For some reason that made me feel slightly nervous.
It's kinda obvious.
/s
There are alternatives though. SELinux was designed for big machines with multiple physical users. You can use it with pretty much any scenario (and Android uses it for sandboxing apps), but AppArmor is much easier for common personal desktops and web servers.
On FreeBSD and Darwin, the similar thing is TrustedBSD: http://www.trustedbsd.org/mac.html