I realize this is somewhat pedantic but I don't think referencing 4.1.2.1 works given how RFC 6749 set things up. Rather I believe that the device flow needs to define and register "access_denied" as a valid token endpoint response error code (it's not a token endpoint response error per RFC 6749 sec 5.2 nor has it been registered https://www.iana.org/assignments/oauth-parameters/oauth-parameters.xhtml#extensions-error ). Also invalid_grant is a a token endpoint response error from RFC 6749 sec 5.2 so that reference is needed and appropriate. RFC 6749 Sec 4.1.2.1 defines errors returned from the authorization endpoint. But the device flow errors are from the token endpoint.
On Wed, May 30, 2018 at 4:27 PM, William Denniss <wdenniss=40google.com@xxxxxxxxxxxxxx> wrote:
Hi Andrew,On Wed, May 30, 2018 at 3:18 PM, Andrew Sciberras <andrewsciberras@pingidentity.com > wrote:Hi WilliamYou 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/OAuth2ForD ) 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.evices#step-6-handle- responses-to-polling-requests Oh, I see what you mean now. Yes, given this is an authorization request, not a token request, the errors from Section 4.1.2.1 are more relevant.I believe it was the authors intention to reference that set of errors, so I will plan to update the doc to reference 4..1.2.1 instead. Good catch! Thank you.On Thu, May 31, 2018 at 8:06 AM, William Denniss <wdenniss@xxxxxxxxxx> wrote:Hi Andrew,On Wed, May 30, 2018 at 2:35 PM, Andrew Sciberras <andrewsciberras@pingidentity.com > 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 <iesg-secretary@xxxxxxxx> 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
ietf@xxxxxxxx mailing lists by 2018-06-12. Exceptionally, comments may be
sent to iesg@xxxxxxxx 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-flo w/
IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-oauth-device-flo w/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)
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