This is an interesting piece on mandatory access-control by the well-known computer researcher and FreeBSD Foundation member Robert Watson:

To discuss operating system security is to marvel at the diversity of deployed access-control models: Unix and Windows NT multiuser security; Type Enforcement in SELinux; anti-malware products; app sandboxing in Apple OS X, Apple iOS, and Google Android; and application-facing systems such as Capsicum in FreeBSD. This diversity is the result of a stunning transition from the narrow 1990s Unix and NT status quo to security localization—the adaptation of operating-system security models to site-local or product-specific requirements.

A Decade of OS Access-control Extensibility