'Add policy rules to the policy enforcer.
For example, if the file listed as property_protection_file has:
[prop_a]
create = glance_creator
then the corresponding policy rule would be:
"prop_a:create": "rule:glance_creator"
where glance_creator is defined in policy.json. For example:
"glance_creator": "role:admin or role:glance_create_user"'

def _add_policy_rules(self, property_exp, action, rule):

    rule = ('rule:%s' % rule)
    rule_name = ('%s:%s' % (property_exp, action))
    rule_dict = policy.Rules.from_dict({rule_name: rule})
    self.policy_enforcer.add_rules(rule_dict)
