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[Rodolfo Alonso <1779003@xxxxxxxxxxxxxxxxxx>]

This bug has not been attended in several years. I'm closing it. Please,
feel free to reopen if needed.

** Changed in: neutron
       Status: New => Won't Fix

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https://bugs.launchpad.net/bugs/1779003

Title:
  Policy check using new attribute value to validate access to the same
  attribute

Status in neutron:
  Won't Fix

Bug description:
  During policy testing using Patrole with the new multi-policy support,
  it became apparent that the Neutron policy enforcement code is using
  the new value of an attribute (on a PUT request) to validate access to
  that same attribute. Here are two scenarios that expose this problem,
  using devstack:

  Scenario 1:
  ----------
   1. Set up Patrole as a Tempest plugin and set the [patrole] parameters in
      tempest.conf.
   2. Set the rbac_test_role to "Member".
   3. Change /etc/neutron/policy.json so that "update_network" and
      "update_network:shared" are defined as "rule:admin_only" (the "Member"
      role is not allowed to update the network)
   4. Change /etc/neutron/policy.json so that "get_network" is defined as
      "rule:shared", so that a "Member" is allowed to view only a shared
      network, but not a non-shared network.
   5. Run the patrole_tempest_plugin.tests.api.network.test_networks_rbac.
      NetworksRbacTest.test_update_network_shared test case. This test has
      recently been modified to test the multi-policy nature of Neutron's
      policy enforcement algorithm.
        - The test case expects a 404 NotFound exception to be raised if the
          role being tested ("Member" in this case) is not allowed to perform
          "get_network". A 403 Forbidden exception is expected if the role is
          not allowed to perform either of the "update_network" or
          "update_network:shared" actions.
   Result:
       With the current Neutron code in master, this test fails with the
       given policy because a 403 Forbidden is thrown instead of the expected
       404 NotFound exception.

       The reason it does not throw the expected 404 is because the "Member"
       role IS allowed to perform "get_network". That is because the Neutron
       policy enforcement code uses the NEW value of the network's "shared"
       attribute in order to check if the rule "get_network" is allowed
       instead of the original value. The original value is shared=False as
       set by the test case, and the test case is modifying it to True. So
       "get_network" should not have been allowed for the Member role here.

       See code snippet: https://github.com/openstack/neutron/blob/
       9cb68ce7777f3016f6affe0abbc7ebe3b859f7c3/neutron/pecan_wsgi/hooks/
       policy_enforcement.py#L123

  Scenario 2: (setup is similar to scenario 1)
  ----------
   The same problem occurs by running the following test case against the
   "Member" role:
       patrole_tempest_plugin.tests.api.network.test_networks_rbac.
           NetworksRbacTest.test_update_network_router_external

   using this set of policy rules:
       - "update_network" and "update_network:router:external" defined as
         "rule:admin_only"
       - "get_network" is defined as "rule:external", so that a "Member" is
         allowed to view only external networks.
   Result:
       Although 404 is expected to be thrown by Neutron due to the
       "get_network" rule, Neutron actually throws a 403 exception, so the
       test case fails. That is because the Neutron policy enforcement code
       uses the NEW value of the network's "external" attribute in order to
       check if the rule "get_network" is allowed instead of the original
       value. The original value is external=False as set by the test case,
       and the test case is modifying it to True. So "get_network" should
       not have been allowed for the Member role here.

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