On 07/22/2014 11:00 PM, Nathan Kinder wrote: > > > On 07/22/2014 06:55 PM, Steven Hardy wrote: >> On Tue, Jul 22, 2014 at 05:20:44PM -0700, Nathan Kinder wrote: >>> Hi, >>> >>> I've had a few discussions recently related to Keystone trusts with >>> regards to imposing restrictions on trusts at a deployment level. >>> Currently, the creator of a trust is able to specify the following >>> restrictions on the trust at creation time: >>> >>> - an expiration time for the trust >>> - the number of times that the trust can be used to issue trust tokens >>> >>> If an expiration time (expires_at) is not specified by the creator of >>> the trust, then it never expires. Similarly, if the number of uses >>> (remaining_uses) is not specified by the creator of the trust, it has an >>> unlimited number of uses. The important thing to note is that the >>> restrictions are entirely in the control of the trust creator. >>> >>> There may be cases where a particular deployment wants to specify global >>> maximum values for these restrictions to prevent a trust from being >>> granted indefinitely. For example, Keystone configuration could specify >>> that a trust can't be created that has >100 remaining uses or is valid >>> for more than 6 months. This would certainly cause problems for some >>> deployments that may be relying on indefinite trusts, but it is also a >>> nice security control for deployments that don't want to allow something >>> so open-ended. >>> >>> I'm wondering about the feasibility of this sort of change, particularly >>> from an API compatibility perspective. An attempt to create a trust >>> without an expires_at value should still be considered as an attempt to >>> create a trust that never expires, but Keystone could return a '403 >>> Forbidden' response if this request violates the maximum specified in >>> configuration (this would be similar for remaining_uses). The semantics >>> of the API remain the same, but the response has the potential to be >>> rejected for new reasons. Is this considered as an API change, or would >>> this be considered to be OK to implement in the v3 API? The existing >>> API docs [1][2] don't really go to this level of detail with regards to >>> when exactly a 403 will be returned for trust creation, though I know of >>> specific cases where this response is returned for the create-trust request. >> >> FWIW if you start enforcing either of these restrictions by default, you >> will break heat, and every other delegation-to-a-service use case I'm aware >> of, where you simply don't have any idea how long the lifetime of the thing >> created by the service (e.g heat stack, Solum application definition, >> Mistral workflow or whatever) will be. >> >> So while I can understand the desire to make this configurable for some >> environments, please leave the defaults as the current behavior and be >> aware that adding these kind of restrictions won't work for many existing >> trusts use-cases. > > I fully agree. In no way should the default behavior change. > >> >> Maybe the solution would be some sort of policy defined exception to these >> limits? E.g when delegating to a user in the service project, they do not >> apply? > > Role-based limits seem to be a natural progression of the idea, though I > didn't want to throw that out there from the get-go.
I was concerned about this idea from an API compatibility perspective, but I think the way you have laid it out here makes sense. Like both you and Steven said, the behavior of the API when the parameter is not specified should *not* change. However, allowing deployment-specific policy that would reject the request seems fine. Thanks, -- Russell Bryant _______________________________________________ OpenStack-dev mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
