Subject, object, operation and permission

We use the terms subject, object, operation and permission consistently with a standard access control literature.

Definition
From a security point of view, we recognize subjects and objects

Subjects are active entities (e.g. UNIX processes) with some behavior. Subjects can designate objects and try to perform some supported operations with them.

What kind of operations can be performed with an object depends on its type.

In general, the set of existing objects and subjects changes over time.

Permissions is a relation that defines which operations on what objects are permitted for particular subjects. One way how to capture permissions is the protection matrix.