Mandatory access controls extend operating system access control policy by allowing administrators to enforce additional constraints on user and application behavior. The TrustedBSD MAC Framework is a kernel programming interface allowing loadable modules to augment the system security policy in order to implement mandatory access control in a flexible manner.

The TrustedBSD MAC Framework first shipped in FreeBSD 5.0, with significant functionality, quality, and performance enhancements in later releases. Supported policy modules include rule-based file system firewall support, TCP/UDP port access control lists, inter-user process visibility controls, as well as classic mandatory access control policies such as Multi-Level Security (MLS) with compartments, and fixed- and floating-label Biba integrity policies. Third party policy modules include cryptographic checksums on system binaries, and SEBSD, a port of the NSA FLASK/SELinux policy to FreeBSD. A number of commercial FreeBSD-based products make use of the TrustedBSD MAC Framework to locally modify the operating system security policy.

MAC Framework and general MAC user documentation and a number of implementation papers may be found on the documentation page.

The TrustedBSD MAC Framework is also present in Mac OS X as of the Leopard release, where it is used to implement Seatbelt and other system security services. The port of the MAC Framework was performed initially as part of SEDarwin, which also included a port of FLASK and SELinux to the Mac OS X platform.