What's wrong with this authorization exchange?

Question

I've set up a MediaWiki server on an Azure website with the PluggableAuth and OpenID Connect extensions. The latter uses the PHP OpenID Connect Basic Client library. I am an administrator in the Azure AD domain example.com, wherein I've created an application with App ID URI, sign-on URL and reply URL all set to https://wiki.azurewebsites.net/. When I navigate to the wiki, I observe the following behavior (cookie values omitted for now):

1. Client Request

   GET https://wiki.azurewebsites.net/ HTTP/1.1

2. RP Request

   GET https://login.windows.net/example.com/.well-known/openid-configuration

3. IP Response

   (some response)

4. RP Response

   HTTP/1.1 302 Moved Temporarily Location: https://login.windows.net/{tenant_id}/oauth2/authorize?response_type=code&redirect_uri=https%3A%2F%2Fwiki.azurewebsites.net%2F&client_id={client_id}&nonce={nonce}&state={state}

5. Client Request

   (follows redirect)

6. IP Response

   HTTP/1.1 302 Found Location: https://wiki.azurewebsites.net/?code={code}&state={state}&session_state={session_state}

7. Client Request

   (follows redirect)

8. RP Request (also repeats #2 & #3)

   POST https://login.windows.net/{tenant_id}/oauth2/token grant_type=authorization_code&code={code}&redirect_uri=https%3A%2F%2Fwiki.azurewebsites.net%2F&client_id={client_id}&client_secret={client_secret}

9. IP Response

   (As interpreted by MediaWiki; I don't have the full response logged at this time)

   AADSTS50001: Resource identifier is not provided.

Note that if I change the OpenID PHP client to provide the 'resource' parameter in step 8, I get the following error response from AAD instead:

8. RP Request

   POST https://login.windows.net/{tenant_id}/oauth2/token grant_type=authorization_code&code={code}&redirect_uri=https%3A%2F%2Fwiki.azurewebsites.net%2F&resource=https%3A%2F%2Fwiki.azurewebsites.net%2F&client_id={client_id}&client_secret={client_secret}

9. IP Response

   AADSTS90027: The client '{client_id}' and resource 'https://wiki.azurewebsites.net/' identify the same application.

   (This has come up before.)

Update

I've made some progress based on @jricher's suggestions, but after working through several more errors I've hit one that I can't figure out. Once this is all done I'll submit pull requests to the affected libraries.

Here's what I've done:

• I've added a second application to the example.com Azure AD domain, with the App ID URI set to mediawiki://wiki.azurewebsites.net/, as a dummy "resource". I also granted the https://wiki.azurewebsites.net/ application delegated access to this new application.

• Passing in the dummy application's URI as the resource parameter in step #8, I'm now getting back the access, refresh, and ID tokens in #9!

• The OpenID Connect library requires that the ID token be signed, but while Azure AD signs the access token it doesn't sign the ID token. It comes with the following properties: {"typ":"JWT","alg":"none"}. So I had to modify the library to allow the caller to specify that unsigned ID tokens are considered "verified". Grrr.

• Okay, next it turns out that the claims can't be verified because the OpenID Provider URL I specified and the issuer URL returned in the token are different. (Seriously?!) So, the provider has to be specified as https://sts.windows.net/{tenant_id}/, and then that works.

• Next, I found that I hadn't run the MediaWiki DB upgrade script for the OpenID Connect extension yet. Thankfully that was a quick fix.

• After that, I am now left with (what I hope is) the final problem of trying to get the user info from AAD's OpenID Connect UserInfo endpoint. I'll give that its own section.

Can't get the user info [Updated]

This is where I am stuck now. After step #9, following one or two intermediate requests to get metadata and keys for verifying the token, the following occurs:

10. RP Request:

    (Updated to use GET with Authorization: Bearer header, per MSDN and the spec.)

    GET https://login.windows.net/{tenant_id}/openid/userinfo Authorization: Bearer {access_token}

11. IP Response:

    400 Bad Request AADSTS50063: Credential parsing failed. AADSTS90010: JWT tokens cannot be used with the UserInfo endpoint.

    (If I change #10 to be either a POST request, with access_token in the body, or a GET request with access_token in the query string, AAD returns the error: AADSTS70000: Authentication failed. UserInfo token is not valid. The same occurs if I use the value of the id_token in place of the access_token value that I received.)

Help?

Update

I'm still hoping someone can shed light on the final issue (the UserInfo endpoint not accepting the bearer token), but I may split that out into a separate question. In the meantime, I'm adding some workarounds to the libraries (PRs coming soon) so that the claims which are already being returned in the bearer token can be used instead of making the call to the UserInfo endpoint. Many thanks to everyone who's helped out with this.

There's also a nagging part of me that wonders if the whole thing would not have been simpler with the OpenID Connect Basic Profile. I assume there's a reason why that was not implemented by the MediaWiki extension.

Update 2

I just came across a new post from Vittorio Bertocci that includes this helpful hint:

...in this request the application is asking for a token for itself! In Azure AD this is possible only if the requested token is an id_token...

This suggests that just changing the token request type in step 8 from authorization_code to id_token could remove the need for the non-standard resource parameter and also make the ugly second AAD application unnecessary. Still a hack, but it feels like much less of one.

Answer 1

Justin is right. For authorization code grant flow, your must specify the resource parameter in either the authorization request or the token request.

Use &resource=https%3A%2F%2Fgraph.windows.net%2F to get an access token for the Azure AD Graph API.

Use &resource=https%3A%2F%2Fmanagement.core.windows.net%2F to get a token for the Azure Service Management APIs.

...

Hope this helps