Re: [OAUTH-WG] Followup on draft-ietf-oauth-token-exchange-12.txt

[Rob Otto <[e-mail]>]

+1 to this.

Rob


On Thu, 17 May 2018 at 13:10, Bill Burke <[e-mail]> wrote:

> My personal opinion is that I'm glad this actor stuff is optional.
> For one, none of our users have asked for it and really only do simple
> exchanges.  Secondly, the rules for who can exchange what for what is
> controlled and defined within our AS.  Makes things a lot simpler on
> the client.  I kind of wish the actor stuff would be defined in a
> separate specification.  I don't see us implementing it unless users
> start asking us to.
>
> On Wed, May 16, 2018 at 6:11 PM, Brian Campbell
> <[e-mail]> wrote:
> > Well, it's already called the "actor claim" so the claimed part is kind
> of
> > implied. And "claimed actor claim" is a rather awkward. Really, all JWT
> > claims are "claimed something" but they don't include the "claimed" bit
> in
> > the name. RFC 7519, for example, defines the subject claim but not the
> > claimed subject claim.
> >
> > On Fri, Apr 20, 2018 at 11:38 AM, Denis <[e-mail]> wrote:
> >>
> >> Brian,
> >>
> >> Eric said: "what is the RP supposed to do when they encounter it? This
> >> seems kind of under specified".
> >>
> >> After reading your explanations below, it looks like the RP can do
> >> anything he wants with the "actor".
> >> It is a "claimed actor" and, if we keep the concept, it should be called
> >> as such. Such a claim cannot be verified.
> >> A RP could copy and paste that claim in an audit log. No standard action
> >> related to the content of such a claim
> >> can be specified in the spec. If the content of a "claimed actor" is
> used
> >> by the RP, it should be only used as an hint
> >> and thus be subject to other verifications which are not specified in
> this
> >> specification.
> >>
> >> Denis
> >>
> >> Eric, I realize you weren't particularly impressed by my prior
> statements
> >> about the actor claim but, for lack of knowing what else to say, I'm
> going
> >> to kind of repeat what I said about it over in the Phabricator tool and
> add
> >> a little color.
> >>
> >> The actor claim is intended as a way to express that delegation has
> >> happened and identify the entities involved. Access control or other
> >> decisions based on it are at the discretion of the consumer of the token
> >> based on whatever policy might be in place.
> >>
> >> There are JWT claims that have concise processing rules with respect to
> >> whether or not the JWT can be accepted as valid. Some examples are "aud"
> >> (Audience), "exp" (Expiration Time), and "nbf" (Not Before) from RFC
> 7519.
> >> E.g. if the token is expired or was intended for someone or something
> else,
> >> reject it.
> >>
> >> And there are JWT claims that appropriately don't specify such
> processing
> >> rules and are solely statements of fact or circumstance. Also from RFC
> 7519,
> >> the "sub" (Subject) and "iat" (Issued At) claims are good examples of
> such.
> >> There might be application or policy specific rules applied to the
> content
> >> of those kinds of claims (e.g. only subjects from a particular
> organization
> >> are able to access tenant specific data or, less realistic but still
> >> possible, disallow access for tokens issued outside of regular business
> >> hours) but that's all outside the scope of a specification's definition
> of
> >> the claim.
> >>
> >> The actor claim falls into the latter category. It's a way for the
> issuer
> >> of the token to tell the consumer of the token what is going on. But any
> >> action to take (or not) based on that information is at the discretion
> of
> >> the token consumer. I honestly don't know it could be anything more. And
> >> don't think it should be.
> >>
> >> There are two main expected uses of the actor claim (that I'm aware of
> >> anyway) that describing here might help. Maybe. One is a human to human
> >> delegation case like a customer service rep doing something on behalf
> of an
> >> end user. The subject would be that user and the actor would be the
> customer
> >> service rep. And there wouldn't be any chaining or nesting of the
> actor. The
> >> other case is so called service chaining where a system might exchange a
> >> token it receives for a new token that it can use to call a downstream
> >> service. And that service in turn might do another exchange to get a new
> >> token suitable to call yet another downstream service. And again and so
> on
> >> and turtles all the way. I'm not necessarily endorsing that level of
> >> granularity in chaining but it's bound to happen somewhere/sometime. The
> >> nested actor claim is able to express that all that has happened with
> the
> >> top level or outermost one being the system currently using the token
> and
> >> prior systems being nested.. What actually gets done with that
> information
> >> is up to the respective systems involved. There might be policy about
> what
> >> system is allowed to call what other system that is enforced. Or maybe
> the
> >> info is just written to an audit log somewhere. Or something else. I
> don't
> >> know. But whatever it is application/deployment/policy dependent and not
> >> specifiable by a spec.
> >>
> >>
> >>
> >>
> >>
> >>
> >> On Fri, Apr 13, 2018 at 6:38 PM, Eric Rescorla <[e-mail]> wrote:
> >>>
> >>> Hi folks,
> >>>
> >>> I've gone over draft-ietf-oauth-token-exchange-12 and things seem
> >>> generally OK. I do still have one remaining concern, which is about
> >>> the actor claim. Specifically, what is the RP supposed to do when they
> >>> encounter it? This seems kind of underspecified.
> >>>
> >>> In particular:
> >>>
> >>> 1. What facts am I supposed to know here? Merely that everyone in
> >>>    the chain signed off on the next person in the chain acting as them?
> >>>
> >>> 2. Am I just supposed to pretend that the person presenting the token
> >>>    is the identity at the top of the chain? Say I have the
> >>>    delegation A -> B -> C, and there is some resource which
> >>>    B can access but A and C cannot, should I give access?
> >>>
> >>> I think the first question definitely needs an answer. The second
> >>> question I guess we could make not answer, but it's pretty hard
> >>> to know how to make a system with this left open..
> >>>
> >>> -Ekr
> >>>
> >>>
> >>> _______________________________________________
> >>> OAuth mailing list
> >>> [e-mail]
> >>> https://www.ietf.org/mailman/listinfo/oauth
> >>>
> >>
> >>
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> >>
> >>
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> >
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>
>
> --
> Bill Burke
> Red Hat
>
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-- 
Rob Otto
EMEA Field CTO - Ping Identity
[phone]

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