[cap-talk] Capability begginer questions

[Matheus Morais]

On 10/3/07, Kevin Reid <kpreid at mac.com> wrote:
>
> This is inconsistent. Randomly generated values are only useful if
> you're creating sparse capabilities (those which the client can
> access the bits of); but the presence of the r_list means that these
> must be protected capabilities (those which the client can't access
> the bits of, or at least can't cause a given bit-sequence to be used
> as a capability).
>
> Assuming that you intend protected capabilities (which have superior
> properties), there is no reason for the "key" to be random; it might
> as well be a pointer or index referring to the implementation of the
> capability (what is invoked/accessed when the capability is used).


Yes your assumption are correct, I'm wanted to create a protected
capabilitie environment. Well, now I'm a bit lost, the key is the identifier
to point for an object which has that capabilitie or for what _action_ that
capabilitie could provide to the object? I was thinking in that manner, the
key is used to identify what object that capabilitie is assigned to and the
r_list will provide what permissions are given by that capabilitie. For
example, when a program P call to write in a file F, the system will check
in P's capability list if the key pointed to F exists and then look what
actions(r_list) will be available to P over F.
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