From LWN.net: "RSBAC is a flexible, powerful and fast open source access control framework
for current Linux kernels, which has been in stable production use for over
a year (since version 1.0.9a).
The standard package includes a range of access control models like MAC, RC,
ACL (see below). Furthermore, the runtime registration facility (REG) makes
it easy to implement your own access control model as a kernel module and
get it registered at runtime."