418 lines
17 KiB
Python
418 lines
17 KiB
Python
# Copyright (c) 2012 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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"""
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Policy engine for tacker. Largely copied from nova.
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"""
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import itertools
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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_utils import excutils
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from oslo_utils import importutils
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import six
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from tacker.api.v1 import attributes
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from tacker.common import exceptions
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import tacker.common.utils as utils
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from tacker.openstack.common import policy
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LOG = logging.getLogger(__name__)
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_POLICY_PATH = None
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_POLICY_CACHE = {}
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ADMIN_CTX_POLICY = 'context_is_admin'
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# Maps deprecated 'extension' policies to new-style policies
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DEPRECATED_POLICY_MAP = {
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'extension:provider_network':
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['network:provider:network_type',
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'network:provider:physical_network',
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'network:provider:segmentation_id'],
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'extension:router':
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['network:router:external'],
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'extension:port_binding':
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['port:binding:vif_type', 'port:binding:vif_details',
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'port:binding:profile', 'port:binding:host_id']
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}
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DEPRECATED_ACTION_MAP = {
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'view': ['get'],
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'set': ['create', 'update']
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}
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cfg.CONF.import_opt('policy_file', 'tacker.common.config')
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def reset():
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global _POLICY_PATH
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global _POLICY_CACHE
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_POLICY_PATH = None
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_POLICY_CACHE = {}
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policy.reset()
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def init():
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global _POLICY_PATH
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global _POLICY_CACHE
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if not _POLICY_PATH:
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_POLICY_PATH = utils.find_config_file({}, cfg.CONF.policy_file)
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if not _POLICY_PATH:
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raise exceptions.PolicyFileNotFound(path=cfg.CONF.policy_file)
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# pass _set_brain to read_cached_file so that the policy brain
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# is reset only if the file has changed
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utils.read_cached_file(_POLICY_PATH, _POLICY_CACHE,
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reload_func=_set_rules)
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def get_resource_and_action(action):
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"""Extract resource and action (write, read) from api operation."""
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data = action.split(':', 1)[0].split('_', 1)
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return ("%ss" % data[-1], data[0] != 'get')
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def _set_rules(data):
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default_rule = 'default'
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LOG.debug(_("Loading policies from file: %s"), _POLICY_PATH)
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# Ensure backward compatibility with folsom/grizzly convention
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# for extension rules
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policies = policy.Rules.load_json(data, default_rule)
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for pol in policies.keys():
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if any([pol.startswith(depr_pol) for depr_pol in
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DEPRECATED_POLICY_MAP.keys()]):
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LOG.warning(_("Found deprecated policy rule:%s. Please consider "
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"upgrading your policy configuration file"), pol)
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pol_name, action = pol.rsplit(':', 1)
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try:
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new_actions = DEPRECATED_ACTION_MAP[action]
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new_policies = DEPRECATED_POLICY_MAP[pol_name]
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# bind new actions and policies together
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for actual_policy in ['_'.join(item) for item in
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itertools.product(new_actions,
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new_policies)]:
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if actual_policy not in policies:
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# New policy, same rule
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LOG.info(_("Inserting policy:%(new_policy)s in place "
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"of deprecated policy:%(old_policy)s"),
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{'new_policy': actual_policy,
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'old_policy': pol})
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policies[actual_policy] = policies[pol]
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# Remove old-style policy
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del policies[pol]
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except KeyError:
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LOG.error(_("Backward compatibility unavailable for "
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"deprecated policy %s. The policy will "
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"not be enforced"), pol)
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policy.set_rules(policies)
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def _is_attribute_explicitly_set(attribute_name, resource, target):
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"""Verify that an attribute is present and has a non-default value."""
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return ('default' in resource[attribute_name] and
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attribute_name in target and
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target[attribute_name] is not attributes.ATTR_NOT_SPECIFIED and
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target[attribute_name] != resource[attribute_name]['default'])
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def _build_subattr_match_rule(attr_name, attr, action, target):
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"""Create the rule to match for sub-attribute policy checks."""
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# TODO(salv-orlando): Instead of relying on validator info, introduce
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# typing for API attributes
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# Expect a dict as type descriptor
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validate = attr['validate']
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key = filter(lambda k: k.startswith('type:dict'), validate.keys())
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if not key:
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LOG.warning(_("Unable to find data type descriptor for attribute %s"),
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attr_name)
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return
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data = validate[key[0]]
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if not isinstance(data, dict):
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LOG.debug(_("Attribute type descriptor is not a dict. Unable to "
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"generate any sub-attr policy rule for %s."),
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attr_name)
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return
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sub_attr_rules = [policy.RuleCheck('rule', '%s:%s:%s' %
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(action, attr_name,
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sub_attr_name)) for
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sub_attr_name in data if sub_attr_name in
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target[attr_name]]
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return policy.AndCheck(sub_attr_rules)
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def _build_match_rule(action, target):
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"""Create the rule to match for a given action.
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The policy rule to be matched is built in the following way:
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1) add entries for matching permission on objects
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2) add an entry for the specific action (e.g.: create_network)
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3) add an entry for attributes of a resource for which the action
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is being executed (e.g.: create_network:shared)
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4) add an entry for sub-attributes of a resource for which the
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action is being executed
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(e.g.: create_router:external_gateway_info:network_id)
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"""
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match_rule = policy.RuleCheck('rule', action)
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resource, is_write = get_resource_and_action(action)
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# Attribute-based checks shall not be enforced on GETs
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if is_write:
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# assigning to variable with short name for improving readability
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res_map = attributes.RESOURCE_ATTRIBUTE_MAP
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if resource in res_map:
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for attribute_name in res_map[resource]:
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if _is_attribute_explicitly_set(attribute_name,
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res_map[resource],
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target):
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attribute = res_map[resource][attribute_name]
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if 'enforce_policy' in attribute:
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attr_rule = policy.RuleCheck('rule', '%s:%s' %
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(action, attribute_name))
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# Build match entries for sub-attributes, if present
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validate = attribute.get('validate')
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if (validate and any([k.startswith('type:dict') and v
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for (k, v) in
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six.iteritems(validate)])):
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attr_rule = policy.AndCheck(
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[attr_rule, _build_subattr_match_rule(
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attribute_name, attribute,
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action, target)])
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match_rule = policy.AndCheck([match_rule, attr_rule])
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return match_rule
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# This check is registered as 'tenant_id' so that it can override
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# GenericCheck which was used for validating parent resource ownership.
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# This will prevent us from having to handling backward compatibility
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# for policy.json
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# TODO(salv-orlando): Reinstate GenericCheck for simple tenant_id checks
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@policy.register('tenant_id')
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class OwnerCheck(policy.Check):
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"""Resource ownership check.
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This check verifies the owner of the current resource, or of another
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resource referenced by the one under analysis.
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In the former case it falls back to a regular GenericCheck, whereas
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in the latter case it leverages the plugin to load the referenced
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resource and perform the check.
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"""
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def __init__(self, kind, match):
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# Process the match
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try:
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self.target_field = re.findall('^\%\((.*)\)s$',
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match)[0]
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except IndexError:
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err_reason = (_("Unable to identify a target field from:%s."
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"match should be in the form %%(<field_name>)s") %
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match)
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LOG.exception(err_reason)
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raise exceptions.PolicyInitError(
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policy="%s:%s" % (kind, match),
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reason=err_reason)
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super(OwnerCheck, self).__init__(kind, match)
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def __call__(self, target, creds):
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if self.target_field not in target:
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# policy needs a plugin check
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# target field is in the form resource:field
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# however if they're not separated by a colon, use an underscore
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# as a separator for backward compatibility
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def do_split(separator):
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parent_res, parent_field = self.target_field.split(
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separator, 1)
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return parent_res, parent_field
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for separator in (':', '_'):
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try:
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parent_res, parent_field = do_split(separator)
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break
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except ValueError:
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LOG.debug(_("Unable to find ':' as separator in %s."),
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self.target_field)
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else:
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# If we are here split failed with both separators
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err_reason = (_("Unable to find resource name in %s") %
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self.target_field)
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LOG.exception(err_reason)
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raise exceptions.PolicyCheckError(
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policy="%s:%s" % (self.kind, self.match),
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reason=err_reason)
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parent_foreign_key = attributes.RESOURCE_FOREIGN_KEYS.get(
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"%ss" % parent_res, None)
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if not parent_foreign_key:
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err_reason = (_("Unable to verify match:%(match)s as the "
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"parent resource: %(res)s was not found") %
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{'match': self.match, 'res': parent_res})
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LOG.exception(err_reason)
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raise exceptions.PolicyCheckError(
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policy="%s:%s" % (self.kind, self.match),
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reason=err_reason)
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# NOTE(salv-orlando): This check currently assumes the parent
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# resource is handled by the core plugin. It might be worth
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# having a way to map resources to plugins so to make this
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# check more general
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# FIXME(ihrachys): if import is put in global, circular
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# import failure occurs
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from tacker import manager
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f = getattr(manager.TackerManager.get_instance().plugin,
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'get_%s' % parent_res)
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# f *must* exist, if not found it is better to let tacker
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# explode. Check will be performed with admin context
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context = importutils.import_module('tacker.context')
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try:
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data = f(context.get_admin_context(),
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target[parent_foreign_key],
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fields=[parent_field])
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target[self.target_field] = data[parent_field]
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except Exception:
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with excutils.save_and_reraise_exception():
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LOG.exception(_('Policy check error while calling %s!'), f)
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match = self.match % target
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if self.kind in creds:
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return match == six.text_type(creds[self.kind])
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return False
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@policy.register('field')
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class FieldCheck(policy.Check):
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def __init__(self, kind, match):
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# Process the match
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resource, field_value = match.split(':', 1)
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field, value = field_value.split('=', 1)
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super(FieldCheck, self).__init__(kind, '%s:%s:%s' %
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(resource, field, value))
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# Value might need conversion - we need help from the attribute map
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try:
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attr = attributes.RESOURCE_ATTRIBUTE_MAP[resource][field]
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conv_func = attr['convert_to']
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except KeyError:
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conv_func = lambda x: x
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self.field = field
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self.value = conv_func(value)
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def __call__(self, target_dict, cred_dict):
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target_value = target_dict.get(self.field)
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# target_value might be a boolean, explicitly compare with None
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if target_value is None:
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LOG.debug(_("Unable to find requested field: %(field)s in "
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"target: %(target_dict)s"),
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{'field': self.field,
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'target_dict': target_dict})
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return False
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return target_value == self.value
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def _prepare_check(context, action, target):
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"""Prepare rule, target, and credentials for the policy engine."""
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# Compare with None to distinguish case in which target is {}
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if target is None:
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target = {}
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match_rule = _build_match_rule(action, target)
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credentials = context.to_dict()
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return match_rule, target, credentials
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def check(context, action, target, plugin=None, might_not_exist=False):
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"""Verifies that the action is valid on the target in this context.
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:param context: tacker 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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: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 plugin: currently unused and deprecated.
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Kept for backward compatibility.
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:param might_not_exist: If True the policy check is skipped (and the
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function returns True) if the specified policy does not exist.
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Defaults to false.
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:return: Returns True if access is permitted else False.
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"""
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if might_not_exist and not (policy._rules and action in policy._rules):
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return True
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return policy.check(*(_prepare_check(context, action, target)))
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def enforce(context, action, target, plugin=None):
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"""Verifies that the action is valid on the target in this context.
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:param context: tacker 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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: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 plugin: currently unused and deprecated.
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Kept for backward compatibility.
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:raises tacker.exceptions.PolicyNotAuthorized: if verification fails.
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"""
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rule, target, credentials = _prepare_check(context, action, target)
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result = policy.check(rule, target, credentials, action=action)
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if not result:
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LOG.debug(_("Failed policy check for '%s'"), action)
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raise exceptions.PolicyNotAuthorized(action=action)
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return result
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def check_is_admin(context):
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"""Verify context has admin rights according to policy settings."""
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init()
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# the target is user-self
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credentials = context.to_dict()
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target = credentials
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# Backward compatibility: if ADMIN_CTX_POLICY is not
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# found, default to validating role:admin
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admin_policy = (ADMIN_CTX_POLICY in policy._rules
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and ADMIN_CTX_POLICY or 'role:admin')
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return policy.check(admin_policy, target, credentials)
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def _extract_roles(rule, roles):
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if isinstance(rule, policy.RoleCheck):
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roles.append(rule.match.lower())
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elif isinstance(rule, policy.RuleCheck):
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_extract_roles(policy._rules[rule.match], roles)
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elif hasattr(rule, 'rules'):
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for rule in rule.rules:
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_extract_roles(rule, roles)
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def get_admin_roles():
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"""Get Admin roles.
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Return a list of roles which are granted admin rights according
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to policy settings.
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"""
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# NOTE(salvatore-orlando): This function provides a solution for
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# populating implicit contexts with the appropriate roles so that
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# they correctly pass policy checks, and will become superseded
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# once all explicit policy checks are removed from db logic and
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# plugin modules. For backward compatibility it returns the literal
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# admin if ADMIN_CTX_POLICY is not defined
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init()
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if not policy._rules or ADMIN_CTX_POLICY not in policy._rules:
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return ['admin']
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try:
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admin_ctx_rule = policy._rules[ADMIN_CTX_POLICY]
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except (KeyError, TypeError):
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return
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roles = []
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_extract_roles(admin_ctx_rule, roles)
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return roles
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