authentication vs authorization was Re: [OpenAFS] 1.3.70 and aklog

[Jeffrey Altman]

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Certainly there is much left to do to make effective use of
2b tokens in AFS.  The Kerberos 5 ticket format allows us to
provide the authorization server (pts) much more information
then was available with earlier token formats.

jhutz commented on Zephyr:

    "But I'd rather have a separate RPC for the fileserver to use for
    mapping authentication names (probably with an auth mech type) to a
    vice ID, and leave PR_NameToID for the task of mapping AFS
    authorization names to vice ID's, since _that_ should remain
    one-to-one

    "In my model, the mappings would be contained in the PRDB, though it
    would also seem reasonable to give the ptserver configuration that
    makes the mapping apply to an entire realm"

There is active discussion in this area.  There is clearly a lot more
work that needs to be done before we can commit to a particular model.

----

In many ways gssklogd provides a gateway service to the AFS cell.
As such you consider the issuance of an AFS token as an authorization
operation.  By doing so the assumption is made that all tokens 
regardless of how they are issued are going to go through an equivalent
gateway service.

The use of Kerberos 5 tickets as tokens breaks this model.  In order to
preserve the gateway model with 2b tokens you would need to hack the KDC
to issue tickets with an alternate client principal name when a ticket
for an AFS service ticket is issued.  This is the primary reason I 
dislike model.  By performing the mapping outside of the PTS it opens
the door for the gateway to be bypassed by a new authentication 
mechanism (perhaps an X.509 cert as a token) and a disruption of the
end user experience.

I am not sure that most organizations which are deploying gssklogd 
understand the distinctions between the authentication and authorization 
models.  Without that understanding, surprises should be expected.

Jeffrey Altman



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