Protection in the Hydra Operating System
Ellis Cohen, David R. Jefferson · ACM SIGOPS Operating Systems Review · 1975
This paper describes the capability based protection mechanisms provided by the Hydra Operating System Kernel. These mechanisms support the construction of user-defined protected subsystems, including file and directory subsystems, which do not therefore need to be supplied directly by Hydra. In addition, we discuss a number of well known protection problems, including Mutual Suspicion, Confinement and Revocation, and we present the mechanisms that Hydra supplies in order to solve them.