The NSA found that most operating systems' security mechanisms, including Windows and most UNIX and Linux systems, only implement "discretionaryaccesscontrol" (DAC) mechanisms.
The first level is the traditional DiscretionaryAccessControl (DAC).
第一级是传统的自主访问控制(Discretionary Access Control, DAC)。
3
Discretionaryaccesscontrol (DAC) is the kernel of most protection mechanism, and the research on safety of DAC concerns whether rights can be leaked to unauthorized subjects.