14.3 Kernel Architecture

The TrustedBSD MAC framework provides the opportunity for policy modules to be augment system access control decisions. Policies are permitted the opportunity to restrict the set of rights available for processes at a variety of relevant points in the kernel. In addition, they are provided the opportunity to tag processes and various kernel objects with labels storing access control information. Policy modules may register interest in a subset of the total available events or objects, and are not required to implement events or objects that are not relevant to the policy. Multiple modules may be loaded at once, and the results of the modules are composed as necessary to build an over-all system policy. Policy modules may be implemented such that they can be loaded on-demand at run-time, or such that they may only be loaded early in the boot process. This permits policies requiring pervasive labeling of all objects to prevent improper use.