Hm... how so? If a server is able to specify in advance which set of scopes it will honor (which may or may not be related to what the client specified in the registration) I can see that being useful. I don’t see a requirement for a linkage between the client’s request and the server’s response. -T
On Thu, Apr 18, 2013 at 9:13 AM, Anthony Nadalin <tony...@microsoft.com>wrote: > If I don’t specify a scope, then the server can allocate a default (or > default set), thus that breaks the semantics you describe**** > > ** ** > > *From:* oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] *On Behalf > Of *Tim Bray > *Sent:* Thursday, April 18, 2013 9:04 AM > *To:* Mike Jones > *Cc:* oauth@ietf.org > > *Subject:* Re: [OAUTH-WG] Registration: Scope Values**** > > ** ** > > I’m unconvinced, Mike. Obviously you’re right about the looseness of > OAuth2 scope specification, but this is a very specific semantic of what > happens when you register, and I don’t think we’re bound by history here. > If we can’t safely say anything about what the list of scopes means, then > I'm with you let's take them out. But the most obvious intended semantic > is (from the client) “I promise to ask only for these” and from the server > “These are the only ones I’ll give you tokens for.” Or does someone have > use-cases for an alternative semantic?**** > > ** ** > > To make this concrete, I propose the following:**** > > “Space-separated list of scope values (as described in OAuth 2.0 Section 3.3 > [RFC6749] <http://tools.ietf.org/html/rfc6749#section-3.3>) that the > client is declaring to the server that it will restrict itself to when > requesting access tokens, and that the server is declaring to the client > that it is registered to use when requesting access tokens. Clients > SHOULD assume that servers will refuse to grant access tokens for scopes > not in the list provided by the server.”**** > > ** ** > > ** ** > > On Thu, Apr 18, 2013 at 8:55 AM, Mike Jones <michael.jo...@microsoft.com> > wrote:**** > > I don’t think it’s possible to define what it means in an interoperable > way because OAuth didn’t specify scopes in an interoperable way. No, I > don’t like that either, but I think that’s where things are. That’s why I > was advocating deleting this registration feature entirely.**** > > **** > > But understanding it might be useful in some contexts, I’m OK keeping it, > provided we be clear that the semantics of “registered to use” are > service-specific.**** > > **** > > -- Mike**** > > **** > > *From:* Tim Bray [mailto:twb...@google.com] > *Sent:* Thursday, April 18, 2013 8:36 AM > *To:* Mike Jones > *Cc:* Justin Richer; oauth@ietf.org**** > > > *Subject:* Re: [OAUTH-WG] Registration: Scope Values**** > > **** > > On the server-to-client side, what does “registered to use” mean? Does it > mean that the client should assume that any scopes not on the list WILL not > be granted, MAY not be granted.... or what? Is this already covered > elsewhere? -T**** > > **** > > On Thu, Apr 18, 2013 at 8:28 AM, Mike Jones <michael.jo...@microsoft.com> > wrote:**** > > Thanks, Justin. I agree with the need for the generic two-sided > language. I’d still keep this language for scope, because we want to > capture the “declaring” aspect in this case:**** > > **** > > “Space separated list of scope values (as described in OAuth 2.0 Section 3.3 > [RFC6749] <http://tools.ietf.org/html/rfc6749#section-3.3>) that the > client is declaring to the server that it may use when requesting access > tokens and that the server is declaring to the client that it is registered > to use when requesting access tokens.”.**** > > **** > > You should probably also reinforce that scope values are service-specific > and may not consist only of a static set of string values, and that > therefore, in some cases, an exhaustive list of registered scope values is > not possible.**** > > **** > > -- Mike**** > > **** > > *From:* Justin Richer [mailto:jric...@mitre.org] > *Sent:* Monday, April 15, 2013 12:29 PM**** > > > *To:* Mike Jones > *Cc:* Tim Bray; oauth@ietf.org > *Subject:* Re: [OAUTH-WG] Registration: Scope Values**** > > **** > > I think that because the "declaration" issue affects all parameters in the > list, not just scope, we should adopt this in a higher level paragraph and > leave it out of the individual parameter descriptions. Thus, something like > this inserted as the second paragraph in section 2:**** > > The client metadata values serve two parallel purposes in the overall > OAuth Dynamic Registration protocol: > > - the Client requesting its desired values for each parameter to the > Authorization Server in a [register] or [update] request, > - the Authorization Server informing the Client of the current values of > each parameter that the Client has been registered to use through a [client > information response]. > > An Authorization Server MAY override any value that a Client requests > during the registration process (including any omitted values) and replace > the requested value with a default. The normative indications in the > following list apply to the Client's declaration of its desired values. > > The Authorization Server SHOULD provide documentation for any fields that > it requires to be filled in by the client or to have particular values or > formats. Extensions and profiles...**** > > > And then remove the sidedness-language from the scope parameter and any > other parameters where it might have crept in inadvertently. > > -- Justin**** > > On 04/15/2013 01:29 PM, Mike Jones wrote:**** > > We could fix the one-sided language by changing**** > > “Space separated list of scope values (as described in OAuth 2.0 Section 3.3 > [RFC6749] <http://tools.ietf.org/html/rfc6749#section-3.3>) that the > client is declaring that it may use when requesting access tokens.”**** > > to**** > > “Space separated list of scope values (as described in OAuth 2.0 Section 3.3 > [RFC6749] <http://tools.ietf.org/html/rfc6749#section-3.3>) that the > client is declaring to the server that it may use when requesting access > tokens and that the server is declaring to the client that it is registered > to use when requesting access tokens.”.**** > > **** > > Again, I chose the “registered to use” language carefully – because in the > general case it’s not a restriction on the values that the client can use – > just a statement by the server to the client that it is registered to use > those particular values. In both cases, the parties are making > declarations to one another.**** > > **** > > If you adopt that language (or keep the original language), then yes, I’d > consider this closed.**** > > **** > > -- Mike**** > > **** > > *From:* Justin Richer [mailto:jric...@mitre.org <jric...@mitre.org>] > *Sent:* Monday, April 15, 2013 9:57 AM > *To:* Mike Jones > *Cc:* Tim Bray; oauth@ietf.org > *Subject:* Re: [OAUTH-WG] Registration: Scope Values**** > > **** > > I absolutely do not want to delete this feature, as (having implemented > it) I think it's very useful. This is a very established pattern in manual > registration: I know of many, many OAuth2 servers and clients that are set > up where the client must pre-register a set of scopes. > > I don't like the language of "the client is declaring" because it's too > one-sided. The client might not have declared anything, and it might be the > server that's declaring something to the client. Deleting the "is > declaring" bit removes that unintended restriction of the language while > keeping the original meaning intact. I actually thought that I had fixed > that before the last draft went in but apparently I missed this one. > > I will work on clarifying the intent of the whole metadata set in its > introductory paragraph(s) so that it's clear that all of these fields are > used in both of these situations: > > 1) The client declaring to the server its desire to use a particular value > 2) The server declaring to the client that it has been registered with a > particular value > > This should hopefully clear up the issue in the editor's note that I > currently have at the top of that section right now, too. > > Mike, since you were the one who originally brought up the issue, and > you're fine with the existing text, can I take this as closed now? Assuming > that you agree with deleting "is declaring" for reasons stated above, I'm > fine with leaving everything else as is and staying quiet on what the > server has to do with the scopes. > > -- Justin**** > > On 04/15/2013 12:44 PM, Mike Jones wrote:**** > > I think that the existing wording is superior to the proposed changed > wording. The existing wording is:**** > > **** > > scope**** > > OPTIONAL. Space separated list of scope values (as described in**** > > OAuth 2.0 Section 3.3 > [RFC6749]<http://tools.ietf.org/html/rfc6749#section-3.3>) > that the client is declaring that**** > > it may use when requesting access tokens. If omitted, an**** > > Authorization Server MAY register a Client with a default set of**** > > scopes.**** > > **** > > For instance, the current “client is declaring” wording will always be > correct, whereas as the change to “client can use” wording implies a > restriction on client behavior that is not always applicable. The “client > is declaring” wording was specific and purposefully chosen, and I think > should be retained. In particular, we can’t do anything that implies that > only the registered scopes values can be used. At the OAuth spec level, > this is a hint as to possible future client behavior – not a restriction on > future client behavior.**** > > **** > > Also, for the reasons that Tim stated, I’m strongly against any “matching” > or “regex” language in the spec pertaining to scopes – as it’s not > actionable.**** > > **** > > So I’d propose that we leave the existing scope wording in place. > Alternatively, I’d also be fine with deleting this feature entirely, as I > don’t think it’s useful in the general case.**** > > **** > > -- Mike**** > > **** > > *From:* oauth-boun...@ietf.org > [mailto:oauth-boun...@ietf.org<oauth-boun...@ietf.org>] > *On Behalf Of *Justin Richer > *Sent:* Monday, April 15, 2013 8:05 AM > *To:* Tim Bray; oauth@ietf.org > *Subject:* Re: [OAUTH-WG] Registration: Scope Values**** > > **** > > On 04/15/2013 10:52 AM, Tim Bray wrote: > > **** > > I’d use the existing wording; it’s perfectly clear. Failing that, if > there’s strong demand for registration of structured scopes, bless the use > of regexes, either PCREs or some careful subset.**** > > > Thanks for the feedback -- Of these two choices, I'd rather leave it > as-is. > > > **** > > **** > > However, I’d subtract the sentence “If omitted, an Authorization Server > MAY register a Client with a default set of scopes.” It adds no value; if > the client doesn’t declare scopes, the client doesn’t declare scopes, > that’s all. -T**** > > > Remember, all of these fields aren't just for the client *request*, > they're also for the server's *response* to either a POST, PUT, or GET > request. (I didn't realize it, but perhaps the wording as stated right now > doesn't make that clear -- I need to fix that.) The value that it adds is > if the client doesn't ask for any particular scopes, the server can still > assign it scopes and the client can do something smart with that. Dumb > clients are allowed to ignore it if it doesn't mean anything to them. > > This is how our server implementation actually works right now. If the > client doesn't ask for anything specific at registration, the server hands > it a bag of "default" scopes. Same thing happens at auth time -- if the > client doesn't ask for any particular scopes, the server hands it all of > its registered scopes as a default. Granted, on our server, scopes are just > simple strings right now, so they get compared at the auth endpoint with an > exact string-match metric and set-based logic. > > -- Justin > > > **** > > **** > > On Mon, Apr 15, 2013 at 7:35 AM, Justin Richer <jric...@mitre.org> wrote:* > *** > > What would you suggest for wording here, then? Keeping in mind that we > cannot (and don't want to) prohibit expression-based scopes. > > -- Justin **** > > **** > > On 04/15/2013 10:33 AM, Tim Bray wrote:**** > > No, I mean it’s not interoperable at the software-developer level. I > can’t register scopes at authorization time with any predictable effect > that I can write code to support, either client or server side, without > out-of-line non-interoperable knowledge about the behavior of the server. > **** > > **** > > I guess I’m just not used to OAuth’s culture of having no expectation that > things will be specified tightly enough that I can write code to implement > as specified. -T**** > > **** > > On Mon, Apr 15, 2013 at 7:15 AM, Justin Richer <jric...@mitre.org> wrote:* > *** > > Scopes aren't meant to be interoperable between services since they're > necessarily API-specific. The only interoperable bit is that there's *some* > place to put the values and that it's expressed as a bag of space-separated > strings. How those strings get interpreted and enforced (which is really > what's at stake here) is up to the AS and PR (or a higher-level protocol > like UMA). > > -- Justin **** > > **** > > On 04/15/2013 10:13 AM, Tim Bray wrote:**** > > This, as written, has zero interoperability. I think this feature can > really only be made useful in the case where scopes are fixed strings.**** > > -T**** > > On Apr 15, 2013 6:54 AM, "Justin Richer" <jric...@mitre.org> wrote:**** > > You are correct that the idea behind the "scope" parameter at registration > is a constraint on authorization-time scopes that are made available. It's > both a means for the client to request a set of valid scopes and for the > server to provision (and echo back to the client) a set of valid scopes. > > I *really* don't want to try to define a matching language for scope > expressions. For that to work, all servers would need to be able to process > the regular expressions for all clients, even if the servers themselves > only support simple-string scope values. Any regular expression syntax we > pick here is guaranteed to be incompatible with something, and I think the > complexity doesn't buy much. Also, I think you suddenly have a potential > security issue if you have a bad regex in place on either end. > > As it stands today, the server can interpret the incoming registration > scopes and enforce them however it wants to. The real trick comes not from > assigning the values to a particular client but to enforcing them, and I > think that's always going to be service-specific. We're just not as clear > on that as we could be. > > After looking over everyone's comments so far, I'd like to propose the > following text for that section: > > **** > > scope**** > > OPTIONAL. Space separated list of scope values (as described in**** > > OAuth 2.0 Section 3.3 [RFC6749] > <http://tools.ietf.org/html/rfc6749#section-3.3>) that the client can use > when **** > > requesting access tokens. As scope values are service-specific, **** > > the Authorization Server MAY define its own matching rules when**** > > determining if a scope value used during an authorization request**** > > is valid according to the scope values assigned during **** > > registration. Possible matching rules include wildcard patterns,**** > > regular expressions, or exactly matching the string. If omitted, **** > > an Authorization Server MAY register a Client with a default **** > > set of scopes.**** > > > Comments? Improvements? > > -- Justin > > **** > > On 04/14/2013 08:23 PM, Manger, James H wrote:**** > > Presumably at app registration time any scope specification is really a > constraint on the scope values that can be requested in an authorization > flow.**** > > **** > > So ideally registration should accept rules for matching scopes, as opposed > to actual scope values.**** > > **** > > You can try to use scope values as their own matching rules. That is fine for > a small set of "static" scopes. It starts to fail when there are a large > number of scopes, or scopes that can include parameters (resource paths? > email addresses?). You can try to patch those failures by allowing services > to define service-specific special "wildcard" scope values that can only be > used during registration (eg "read:*").**** > > **** > > Alternatively, replace 'scope' in registration with 'scope_regex' that holds > a regular expression that all scope values in an authorization flow must > match.**** > > **** > > --**** > > James Manger**** > > _______________________________________________**** > > OAuth mailing list**** > > OAuth@ietf.org**** > > https://www.ietf.org/mailman/listinfo/oauth**** > > **** > > > _______________________________________________ > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth**** > > **** > > **** > > **** > > **** > > **** > > **** > > **** > > **** > > ** ** >
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