06c0fd4fd2
Move default target from context.can() into policy.authorize() so it is easier to unit test the context behaviour. This was not done originally due to this meaning placement avoided the strange default target, but that is no longer required. Change-Id: I23c433dcd459e7f930ac2eb8a3583c857836cae2
257 lines
9.1 KiB
Python
257 lines
9.1 KiB
Python
# Copyright (c) 2011 OpenStack Foundation
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Policy Engine For Nova."""
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import copy
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import re
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from oslo_config import cfg
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from oslo_log import log as logging
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from oslo_policy import policy
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from oslo_utils import excutils
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from nova import exception
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from nova.i18n import _LE, _LW
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from nova import policies
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CONF = cfg.CONF
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LOG = logging.getLogger(__name__)
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_ENFORCER = None
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# This list is about the resources which support user based policy enforcement.
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# Avoid sending deprecation warning for those resources.
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USER_BASED_RESOURCES = ['os-keypairs']
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# oslo_policy will read the policy configuration file again when the file
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# is changed in runtime so the old policy rules will be saved to
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# saved_file_rules and used to compare with new rules to determine the
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# rules whether were updated.
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saved_file_rules = []
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KEY_EXPR = re.compile(r'%\((\w+)\)s')
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def reset():
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global _ENFORCER
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if _ENFORCER:
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_ENFORCER.clear()
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_ENFORCER = None
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def init(policy_file=None, rules=None, default_rule=None, use_conf=True):
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"""Init an Enforcer class.
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:param policy_file: Custom policy file to use, if none is specified,
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`CONF.policy_file` will be used.
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:param rules: Default dictionary / Rules to use. It will be
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considered just in the first instantiation.
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:param default_rule: Default rule to use, CONF.default_rule will
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be used if none is specified.
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:param use_conf: Whether to load rules from config file.
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"""
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global _ENFORCER
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global saved_file_rules
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if not _ENFORCER:
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_ENFORCER = policy.Enforcer(CONF,
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policy_file=policy_file,
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rules=rules,
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default_rule=default_rule,
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use_conf=use_conf)
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register_rules(_ENFORCER)
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_ENFORCER.load_rules()
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# Only the rules which are loaded from file may be changed.
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current_file_rules = _ENFORCER.file_rules
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current_file_rules = _serialize_rules(current_file_rules)
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# Checks whether the rules are updated in the runtime
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if saved_file_rules != current_file_rules:
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_warning_for_deprecated_user_based_rules(current_file_rules)
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saved_file_rules = copy.deepcopy(current_file_rules)
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def _serialize_rules(rules):
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"""Serialize all the Rule object as string which is used to compare the
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rules list.
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"""
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result = [(rule_name, str(rule))
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for rule_name, rule in rules.items()]
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return sorted(result, key=lambda rule: rule[0])
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def _warning_for_deprecated_user_based_rules(rules):
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"""Warning user based policy enforcement used in the rule but the rule
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doesn't support it.
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"""
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for rule in rules:
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# We will skip the warning for the resources which support user based
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# policy enforcement.
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if [resource for resource in USER_BASED_RESOURCES
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if resource in rule[0]]:
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continue
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if 'user_id' in KEY_EXPR.findall(rule[1]):
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LOG.warning(_LW("The user_id attribute isn't supported in the "
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"rule '%s'. All the user_id based policy "
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"enforcement will be removed in the "
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"future."), rule[0])
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def set_rules(rules, overwrite=True, use_conf=False):
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"""Set rules based on the provided dict of rules.
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:param rules: New rules to use. It should be an instance of dict.
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:param overwrite: Whether to overwrite current rules or update them
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with the new rules.
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:param use_conf: Whether to reload rules from config file.
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"""
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init(use_conf=False)
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_ENFORCER.set_rules(rules, overwrite, use_conf)
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def authorize(context, action, target=None, do_raise=True, exc=None):
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"""Verifies that the action is valid on the target in this context.
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:param context: nova context
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:param action: string representing the action to be checked
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this should be colon separated for clarity.
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i.e. ``compute:create_instance``,
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``compute:attach_volume``,
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``volume:attach_volume``
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:param target: dictionary representing the object of the action
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for object creation this should be a dictionary representing the
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location of the object e.g. ``{'project_id': instance.project_id}``
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If None, then this default target will be considered:
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{'project_id': self.project_id, 'user_id': self.user_id}
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:param do_raise: if True (the default), raises PolicyNotAuthorized;
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if False, returns False
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:param exc: Class of the exception to raise if the check fails.
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Any remaining arguments passed to :meth:`authorize` (both
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positional and keyword arguments) will be passed to
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the exception class. If not specified,
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:class:`PolicyNotAuthorized` will be used.
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:raises nova.exception.PolicyNotAuthorized: if verification fails
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and do_raise is True. Or if 'exc' is specified it will raise an
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exception of that type.
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:return: returns a non-False value (not necessarily "True") if
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authorized, and the exact value False if not authorized and
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do_raise is False.
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"""
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init()
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credentials = context.to_policy_values()
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if not exc:
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exc = exception.PolicyNotAuthorized
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# Legacy fallback for emtpy target from context.can()
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# should be removed once we improve testing and scope checks
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if target is None:
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target = default_target(context)
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try:
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result = _ENFORCER.authorize(action, target, credentials,
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do_raise=do_raise, exc=exc, action=action)
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except policy.PolicyNotRegistered:
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with excutils.save_and_reraise_exception():
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LOG.exception(_LE('Policy not registered'))
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except Exception:
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with excutils.save_and_reraise_exception():
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LOG.debug('Policy check for %(action)s failed with credentials '
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'%(credentials)s',
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{'action': action, 'credentials': credentials})
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return result
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def default_target(context):
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return {'project_id': context.project_id, 'user_id': context.user_id}
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def check_is_admin(context):
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"""Whether or not roles contains 'admin' role according to policy setting.
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"""
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init()
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# the target is user-self
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credentials = context.to_policy_values()
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target = default_target(context)
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return _ENFORCER.authorize('context_is_admin', target, credentials)
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@policy.register('is_admin')
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class IsAdminCheck(policy.Check):
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"""An explicit check for is_admin."""
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def __init__(self, kind, match):
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"""Initialize the check."""
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self.expected = (match.lower() == 'true')
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super(IsAdminCheck, self).__init__(kind, str(self.expected))
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def __call__(self, target, creds, enforcer):
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"""Determine whether is_admin matches the requested value."""
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return creds['is_admin'] == self.expected
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def get_rules():
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if _ENFORCER:
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return _ENFORCER.rules
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def register_rules(enforcer):
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enforcer.register_defaults(policies.list_rules())
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def get_enforcer():
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# This method is used by oslopolicy CLI scripts in order to generate policy
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# files from overrides on disk and defaults in code.
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cfg.CONF([], project='nova')
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init()
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return _ENFORCER
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def verify_deprecated_policy(old_policy, new_policy, default_rule, context):
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"""Check the rule of the deprecated policy action
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If the current rule of the deprecated policy action is set to a non-default
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value, then a warning message is logged stating that the new policy
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action should be used to dictate permissions as the old policy action is
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being deprecated.
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:param old_policy: policy action that is being deprecated
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:param new_policy: policy action that is replacing old_policy
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:param default_rule: the old_policy action default rule value
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:param context: the nova context
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"""
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if _ENFORCER:
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current_rule = str(_ENFORCER.rules[old_policy])
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else:
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current_rule = None
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if current_rule != default_rule:
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LOG.warning("Start using the new action '%(new_policy)s'. "
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"The existing action '%(old_policy)s' is being deprecated "
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"and will be removed in future release.",
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{'new_policy': new_policy, 'old_policy': old_policy})
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context.can(old_policy)
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return True
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else:
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return False
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