Re: [OAUTH-WG] Last Call: <draft-ietf-oauth-device-flow-09.txt> (OAuth 2.0 Device Flow for Browserless and Input Constrained Devices) to Proposed Standard

[Andrew Sciberras <[e-mail]>]

Hi William

You are right that the document explicitly indicates which error codes may
be returned. However I think it's ambiguous as to which error within
Section 5.2 of RFC6749 would apply in the scenario of a user not granting
access.

I think that this ambiguity is highlighted further by the Google
implementation (https://developers.google.com/identity/protocols/OAuth2ForDe
vices#step-6-handle-responses-to-polling-requests) not adhering to the
explicit statement of the document and electing to use a (more appropriate)
error code that exists outside of section 5.2.

Andrew


On Thu, May 31, 2018 at 8:06 AM, William Denniss <[e-mail]>
wrote:

> Hi Andrew,
>
> On Wed, May 30, 2018 at 2:35 PM, Andrew Sciberras <[e-mail]> wrote:
>
> Hello
>>
>>
>> Do we feel that the document should be more specific in addressing how
>> the authorization service should respond to a device access token request
>> when the user has refused to grant access to the device?
>>
>>
>> The document currently indicates in section 3.5 that a success response
>> defined in section 5.1 of RFC6749, an error as defined in section 5.2 of
>> RFC6749 (this includes invalid_request, invalid_client, invalid_grant,
>> unauthorized_client, unsupported_grant_type, and invalid_scope), or a new
>> device flow error code (authorization_pending, slow_down, and
>> expired_token) may be returned in a response to a device token request.
>>
>>
>> It doesn’t seem that any of these options are appropriate to convey that
>> a user has refused to grant access to the device.
>>
>>
>> The Google implementation appears to be using the access_denied error
>> code from section 4.1.2.1 of RFC6749. While this would seem to be the most
>> suitable error code, the document does not explicitly indicate it as a
>> permitted response.
>>
>
> Actually, this is indicated explicitly I believe:
>
> If the user has approved the grant, the token endpoint responds with a
> success response defined in Section 5.1 of [RFC6749]; *otherwise it
> responds with an error, as defined in Section 5.2 of [RFC6749].*
>
In addition to the error codes defined in Section 5.2 of [RFC6749], the
> following error codes are specific for the device flow:
>
>
>>
>> I believe that clarifying the response error code in the condition where
>> a user has refused access to the client would be beneficial, remove
>> ambiguity, and promote greater consistency across implementations.
>>
>>
>> Regards
>>
>> Andrew Sciberras
>>
>>
>> On Wed, May 30, 2018 at 8:20 AM, The IESG <[e-mail]>
>> wrote:
>>
>>>
>>> The IESG has received a request from the Web Authorization Protocol WG
>>> (oauth) to consider the following document: - 'OAuth 2.0 Device Flow for
>>> Browserless and Input Constrained Devices'
>>>   <draft-ietf-oauth-device-flow-09.txt> as Proposed Standard
>>>
>>> The IESG plans to make a decision in the next few weeks, and solicits
>>> final
>>> comments on this action. Please send substantive comments to the
>>> [e-mail] mailing lists by 2018-06-12. Exceptionally, comments may
>>> be
>>> sent to [e-mail] instead. In either case, please retain the
>>> beginning of
>>> the Subject line to allow automated sorting.
>>>
>>> Abstract
>>>
>>>
>>>    This OAuth 2.0 authorization flow for browserless and input
>>>    constrained devices, often referred to as the device flow, enables
>>>    OAuth clients to request user authorization from devices that have an
>>>    Internet connection, but don't have an easy input method (such as a
>>>    smart TV, media console, picture frame, or printer), or lack a
>>>    suitable browser for a more traditional OAuth flow.  This
>>>    authorization flow instructs the user to perform the authorization
>>>    request on a secondary device, such as a smartphone.  There is no
>>>    requirement for communication between the constrained device and the
>>>    user's secondary device.
>>>
>>>
>>>
>>>
>>> The file can be obtained via
>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-device-flow/
>>>
>>> IESG discussion can be tracked via
>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-device-flow/ballot/
>>>
>>>
>>> No IPR declarations have been submitted directly on this I-D.
>>>
>>>
>>> The document contains these normative downward references.
>>> See RFC 3967 for additional information:
>>>     rfc6819: OAuth 2.0 Threat Model and Security Considerations
>>> (Informational - IETF stream)
>>>     draft-recordon-oauth-v2-device: OAuth 2.0 Device Profile
>>>  (None - )
>>>     rfc6755: An IETF URN Sub-Namespace for OAuth (Informational - IETF
>>> stream)
>>>
>>>
>>>
>>> _______________________________________________
>>> OAuth mailing list
>>> [e-mail]
>>> https://www.ietf.org/mailman/listinfo/oauth
>>>
>>
>>
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>

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