[keycloak-dev] Wildcard for Valid Redirect URI Hostname

Tue Sep 20 14:42:55 EDT 2016

There’s a REST endpoint and we use it via Resteasy:

ClientRepresentation client = keycloak.realm(realmName).clients().get(clientId);
client.setRedirectUris(…);

Scott Rossillo
Smartling | Senior Software Engineer
srossillo at smartling.com

> On Sep 20, 2016, at 10:49 AM, Thomas Darimont <thomas.darimont at googlemail.com> wrote:
> 
> Great discussion with a lot of interesting points!
> 
> I think being more flexible with respect to redirect URI's would be very helpful.
> 
> I wonder whether one could provide a REST endpoint a developer could use to register an additional redirect URI 
> for an existing client - given that the developer provides the clientId, clientSecret -> service account. 
> 
> With this a developer could "unlock" his machine enable for a particular client. One way to do that would be to register a custom REST Resource in Keycloak which only allows requests from the service-accounts of a particular client. The resource could then simply lookup the appropriate client configuration and update the allowed redirect paths. 
> 
> Adding paths should trigger an AdminEvent to provide an audit trail.
> 
> Cheers,
> Thomas
> 
> 2016-09-20 16:15 GMT+02:00 Josh Cain <josh.cain at redhat.com <mailto:josh.cain at redhat.com>>:
> So I certainly get that we want to be as close to the spec as possible - wholeheartedly agree.  However, I'd also like to reiterate that the main purpose of this is for lower/developer environments in which there are a large number of developers who are frequently spinning up sanboxes with apps that need SSO capabilities.  Unless I want to open up the GUI in these environments to the world, I'm left without a good CM option for Keycloak.  Any suggestions on the management of this?  Right now I'm looking at a high amount of manual overhead, or scripting it out with some one-off config scripts that I'll have to wind up maintaining.  Neither option sounds appealing.
> 
> Hope you didn't get the wrong impression from the PR - I noted a javascript library that was shared across several pages within a number of subdomains.  All pages share a similar look and feel, but due to the nature of the content and topic can live at different subdomains or even have slightly different page content implementations.  Are we really going to make the assertion that a 'client' cannot span subdomains?  That seems to be the implication here.  And if so, is that necessarily more 'secure', or does that just mean that implementers could simply favor a single domain name with varying paths instead of categorically organized subdomains?  Seems like an implementation detail that can easily be circumvented and does not inherently make an enclave more or less secure.
> 
> I completely agree with your argument that we should be striving for the finest level of granularity with respect to client definition.  I understand the intentional segregation of logical clients by the specification so as to keep one compromised client from affecting the entire SSO ecosystem.  However, I do think that there is a solid case for a single 'client' that does stuff like spans subdomains, and that such a client could be used in a secure manner.
> 
> At the end of the day, it feels like we're trying to force a definition on what is a client.  The discussion seems to acknowledge that 'real world' application of this spec find wildcards useful (as your suggestion for supporting them in the path), however the manner in which they're used appropriately is up for debate.  If we're living outside the spec anyway, do we really have a firm leg to stand on for the assertion that clients can have different paths but not subdomains?  I don't see a solid reason for this one.
> 
> Some other thoughts I had on this that might be useful:
> Some of the rub here is that maintaining a list of valid redirects for something like string matching is a CM nightmare (particularly in dev-ish environments).  Something like an SPI to drop an implementation in here where I can apply a little more powerful logic would also do the job.  Could this be used nefariously or poorly to circumvent the specification?  yeah, sure - but so can Authenticators, and they're seen as a useful tool whereby developers can extend necessary functionality.
> Would you also consider something like a 'development mode' flag that allowed for different options such as wildcards in different URL parts?  Would have to add a little more validation to define what is and is not allowed, but would be useful for this case.
> 
> Thanks for good the discussion.  As always, learning much and enjoying it!
> 
> 
> Josh Cain | Software Applications Engineer
> Identity and Access Management
> Red Hat
> +1 256-452-0150 <tel:%2B1%20256-452-0150>
> 
> On Tue, Sep 20, 2016 at 1:20 AM, Stian Thorgersen <sthorger at redhat.com <mailto:sthorger at redhat.com>> wrote:
> I appreciate this feature might be useful, so there's no need to discuss that aspect. The only issue I have with this PR is with regards to security and especially as it enables doing the "wrong" thing.
> 
> With regards to redirect URIs with confidential clients they are still important, but not quite as important as they are for public client. This means redirect URIs can typically be more flexible with confidential clients without a significant risk.
> 
> For public clients it's very important to lock these down as much as possible as they are the ONLY way to prevent malicious clients to gain access to the SSO session. This means we should actually tighten the requirements for redirect URIs not further relax them. For public clients the redirect URIs:
> 
> * Should be as specific as possible. We should only allow wildcard in the path. I believe we should introduce this for both public and confidential clients.
> * Require HTTPs unless it's http://localhost <http://localhost/>. This is not so easy in development, so maybe we should have an option to run the server in "unsafe" mode for developers.
> 
> Here's a quote from the OIDC spec around this:
> 
> "REQUIRED. Redirection URI to which the response will be sent. This URI MUST exactly match one of the Redirection URI values for the Client pre-registered at the OpenID Provider, with the matching performed as described in Section 6.2.1 of [RFC3986] (Simple String Comparison). The Redirection URI SHOULD use the https scheme; however, it MAY use the http scheme, provided that the Client Type is confidential, as defined in Section 2.1 of OAuth 2.0, and provided the OP allows the use of http Redirection URIs in this case. The Redirection URI MAY use an alternate scheme, such as one that is intended to identify a callback into a native application."
> 
> Looking at your comments on the PR it worries me slightly that you have a shared client for a "library". A library is not a client. A client is an instance of an application. Sharing the client will have impact on audit, what clients a user believes they are authenticated to. With regards to wildcard to allow any subdomains that is scary as your allowing any piece of code running on any subdomain within your domain to authenticate via that particular client. That could be an infected forum, something any user has executing, etc.. As long as the redirect URI permits it an application can obtain a token for a client for a user that is authenticated without the user knowing about it. Unless you enable consent that is, but if the user used the "real" client they would have given consent and the malicious client on a different subdomain can take advantage of it.
> 
> In summary my opinion is that we can't accept this PR and that we further:
> 
> * Allow wildcard only in path. This is actually still looser than the OIDC spec mandates as it requires a simple string comparison.
> * Require HTTPS (or custom scheme) for public clients. We may need a development mode that disables this.
> 
> 
> 
> On 19 September 2016 at 16:50, Josh Cain <josh.cain at redhat.com <mailto:josh.cain at redhat.com>> wrote:
> Per KEYCLOAK-3585: <https://issues.jboss.org/browse/KEYCLOAK-3585>
> Currently, valid redirect URI hostnames allow for wildcards at the end like so:
> 
> 
> http://www.redhat.com/* <http://www.redhat.com/*>
> 
> I'm managing several environments where clients need 'n' number of available redirect URI's with different hostnames, I.E.
> 
> 
> http://developer1.env.redhat.com <http://developer1.env.redhat.com/>
> http://developer2.env.redhat.com <http://developer2.env.redhat.com/>
> http://developer3.env.redhat.com <http://developer3.env.redhat.com/>
> 
> Would really help to have the ability to wildcard hostnames too, I.E.:
> 
> 
> http://*.env.redhat.com <http://env.redhat.com/>
> 
> I've submitted #3241 <https://github.com/keycloak/keycloak/pull/3241> to address this issue, but there seem to be some concerns about allowing wildcards in other parts of the URL.  See the PR for a more fleshed out discussion, but wanted to start a thread here on the mailing list.  Particularly with respect to:
> Does anyone have need of this feature or would find it useful?
> Should this kind of wildcard be allowed as a configuration option by Keycloak?
> Josh Cain | Software Applications Engineer
> Identity and Access Management
> Red Hat
> +1 256-452-0150 <tel:%2B1%20256-452-0150>
> 
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