RPC dispatch should restrict methods to those that are explicitly exposed

[Christopher Armstrong]

The RPC dispatcher should not allow calling any method on RPC proxy objects. Even though the RPC mechanism is meant to be entirely internal on a secure transport, there should be a reasonable attempt at security to prevent exposing internal methods of service implementations.

The following document implicitly describes an "rpc.expose" decorator which is used to specify which methods should be exposed. This should be implemented and required for future versions of code that use Oslo RPC.

https://wiki.openstack.org/wiki/Oslo/Messaging

[Christopher Armstrong (radix)]

Apart from the security concern, I think an expose decorator makes the code much more clear, so readers can easily determine which methods of an RPC proxy are public and which are implementation helpers.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/358359

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/358359
Committed: https://git.openstack.org/cgit/openstack/oslo.messaging/commit/?id=d3a8f280ebd6fd12865fd20c4d772774e39aefa2
Submitter: Jenkins
Branch: master

commit d3a8f280ebd6fd12865fd20c4d772774e39aefa2
Author: Paul Vinciguerra <email address hidden>
Date: Sun Aug 21 19:46:28 2016 -0400

    Allow dispatcher to restrict endpoint methods.

    Implements access_policy for dispatcher to restrict endpoint methods.

    Implements the following access policies:
    * LegacyRPCAccessPolicy
    * DefaultRPCAccessPolicy
    * ExplicitRPCAccessPolicy

    * Implement decorator @rpc.expose for use with the
     ExplicitRPCAccessPolicy

    * Modify get_rpc_server to allow optional access_policy argument
    * Set default access_policy to LegacyRPCAccessPolicy (Nova exposes
     _associate_floating_ip in tempest tests). Added debtcollector
     notification.
    * Add test cases for access_policy=None
    * Clarify documentation

    Change-Id: I42239e6c8a8be158ddf5c3b1773463b7dc93e881
    Closes-Bug: 1194279
    Closes-Bug: 1555845

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.messaging 5.11.0 release.