258 lines
9.1 KiB
Python
258 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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import sys
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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, 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': context.project_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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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 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 = credentials
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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 for use by oslopolicy CLI scripts. Those scripts need the
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# 'output-file' and 'namespace' options, but having those in sys.argv means
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# loading the Nova config options will fail as those are not expected to
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# be present. So we pass in an arg list with those stripped out.
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conf_args = []
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# Start at 1 because cfg.CONF expects the equivalent of sys.argv[1:]
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i = 1
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while i < len(sys.argv):
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if sys.argv[i].strip('-') in ['namespace', 'output-file']:
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i += 2
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continue
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conf_args.append(sys.argv[i])
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i += 1
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cfg.CONF(conf_args, 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 '{0}'. The existing "
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"action '{1}' is being deprecated and will be "
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"removed in future release.".format(new_policy,
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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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