0de548c3ab
The policy engine is currently being called for every attribute of every resource to be returned by a list response. This is harming the API performance; moreover such a high number of checks is also unnecessary. This patch therefore slightly changes the API logic so that list response first determine the list of attributes which should be returned querying the policy engine and then use this list for all resource items to be returned. To this aim a few methods in base.py needed to be refactored. This patch also removes the routine check_if_exists from policy.py and the related PolicyNotFound exception. Finally, this patch also removes unnecessary admin_or_owner rules when applied to attributes. This kind of rule indeed has no effect anyway because of Neutron's ownership checks. The rules were removed because this change won't allow anymore for having attribute-level policies whose evaluation result depends on the resource value. Implements blueprint faster-list-responses Change-Id: I21b8273add5d5984f512ad94af5a99cf0b0a5d93
415 lines
17 KiB
Python
415 lines
17 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# 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 neutron. 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 neutron.api.v2 import attributes
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from neutron.common import exceptions
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import neutron.common.utils as utils
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from neutron import manager
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from neutron.openstack.common import excutils
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from neutron.openstack.common import importutils
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from neutron.openstack.common import log as logging
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from neutron.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', 'neutron.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.warn(_("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.warn(_("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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validate.iteritems()])):
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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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f = getattr(manager.NeutronManager.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 neutron
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# explode. Check will be performed with admin context
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context = importutils.import_module('neutron.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 == unicode(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: neutron 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: neutron 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 neutron.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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"""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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