Illffe, J. K., Basic Machine Principles, American Elsevier, New York, 1968. Protection 10  Home/Search   Document Not in Database   Summary   Related Articles

....a given domain d can access, or at least the objects for which d is responsible or is paying for. An implementation which attacks (b) and (d) directly is to attach the d th column of A to the domain d in the form of a table of pairs x, A d,x . One of these pairs is usually called a capability [3, 7, 9, 10, 15]. If the hardware provides for read only arrays which can only be generated by the supervisor, then each capability can be implemented as such an array, containing: The name of the object (a 64 bit integer) A suitable representation of the access attributes (perhaps as a bit string) Most ....

....an interesting exercise to devise a mechanism for controlling who gets to alter this additional information. Capabilities can also be used to attack problem (c) above. All we have to do is observe that it is possible to build an arbitrary graph of domains, each with a set of capabi1ities or C list [3, 7, 13]. Protection 8 Everything we know about tree structured naming schemes can then be applied to economize on storage for shared capabilities. A completely different approach is to attach the protection information to the object rather than the domain. In its most general form, the idea is to ....

Illffe, J. K., Basic Machine Principles, American Elsevier, New York, 1968. Protection 10

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