Identity Provider Specific WebSSO

bp federation-idp-websso

Currently the way keystone handles websso is global for each protocol in the keystone instance. This requires some form of web page discovery service implemented on top of keystone to allow users to select their provider.

In more simplistic deployments I want to be able to configure multiple saml providers that can be selected from the horizon drop down menu rather than an additional service.

Problem Description

Currently WebSSO is configured in a global sense for keystone. You have to pick a handler for /v3/auth/OS-FEDERATION/websso with a single apache module, this route should offer some form of handler that will typically involve IdP discovery and selection that redirects to the actual IdP handler.

To handle multiple IdPs this relies on the apache module having discovery capability and the deployer constructing a webpage that shows the available alternatives.

If your list of IdPs is fairly static it would be much better to simply have horizon handle this. It already has a drop down selection to enable you to select identity provider and it would be useful to be able to configure individual identity providers to show up there. I should be able to select google or facebook as my IdP and not care that they both use SAML from a keystone perspective.

Proposed Change

In addition to the /v3/auth/OS-FEDERATION/websso/{protocol} path we add a similar handler at /v3/auth/OS-FEDERATION/identity_providers/{idp_ip}/protocol/{protocol_id}/websso. Rather than being dynamic, using remote-id to lookup the IdP that this relates to this route will be handled only by the IdP specified in the URL.

This would allow the configuration of /v3/auth/OS-FEDERATION/identity_providers/{idp_ip}/protocol/{protocol_id} that is done for the CLI to also handle the websso case.

Alternatives

We could continue with the global approach.

Security Impact

This is more secure than the current approach. When websso requests return to keystone the global handler asserts that some configured Apache module has verified the request. If I have both Google and Facebook SAML providers I must validate against either of them and then we use the remote-ids parameter of a keystone IdP to ensure that the URL that issued the assertion is one of those already known and we discover mappings that way.

With this change we would have separate URLs for instigating websso against Google or Facebook and the Apache module is configured to only allow assertions from the configure remote IdP.

Notifications Impact

None

Other End User Impact

This would be configured in django_openstack_auth. It would not be directly used by a user.

Performance Impact

None

Other Deployer Impact

This may change the way you configure apache for keystone. In the event that you are also enabling federation via the command line it will simplify it as you only need to configure the one location rather than one for CLI and one for websso.

Developer Impact

Discuss things that will affect other developers working on OpenStack, such as:

  • If the blueprint proposes a change to the driver API, discussion of how other backends would implement the feature is required.

Implementation

Assignee(s)

Primary assignee:
jamielennox
Other contributors:
marekd lbragstad

Work Items

  • Add a /v3/auth/OS-FEDERATION/identity_providers/{idp_ip}/protocol/{protocol_id}/websso path to keystone.
  • Allow configuring django_openstack_auth to use an individual IdP websso mechanism rather than the global endpoint.

Dependencies

None

Documentation Impact

Document new URIs.