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@ -1,962 +0,0 @@
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# -*- coding: utf-8 -*-
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#
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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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Common Policy Engine Implementation
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Policies can be expressed in one of two forms: A list of lists, or a
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string written in the new policy language.
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In the list-of-lists representation, each check inside the innermost
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list is combined as with an "and" conjunction--for that check to pass,
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all the specified checks must pass. These innermost lists are then
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combined as with an "or" conjunction. As an example, take the following
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rule, expressed in the list-of-lists representation::
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[["role:admin"], ["project_id:%(project_id)s", "role:projectadmin"]]
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This is the original way of expressing policies, but there now exists a
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new way: the policy language.
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In the policy language, each check is specified the same way as in the
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list-of-lists representation: a simple "a:b" pair that is matched to
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the correct class to perform that check::
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+===========================================================================+
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| TYPE | SYNTAX |
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+===========================================================================+
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|User's Role | role:admin |
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+---------------------------------------------------------------------------+
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|Rules already defined on policy | rule:admin_required |
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+---------------------------------------------------------------------------+
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|Against URL's¹ | http://my-url.org/check |
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+---------------------------------------------------------------------------+
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|User attributes² | project_id:%(target.project.id)s |
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+---------------------------------------------------------------------------+
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|Strings | <variable>:'xpto2035abc' |
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| | 'myproject':<variable> |
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+---------------------------------------------------------------------------+
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| | project_id:xpto2035abc |
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|Literals | domain_id:20 |
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| | True:%(user.enabled)s |
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+===========================================================================+
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¹URL checking must return 'True' to be valid
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²User attributes (obtained through the token): user_id, domain_id or project_id
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Conjunction operators are available, allowing for more expressiveness
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in crafting policies. So, in the policy language, the previous check in
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list-of-lists becomes::
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role:admin or (project_id:%(project_id)s and role:projectadmin)
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The policy language also has the "not" operator, allowing a richer
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policy rule::
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project_id:%(project_id)s and not role:dunce
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Attributes sent along with API calls can be used by the policy engine
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(on the right side of the expression), by using the following syntax::
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<some_value>:%(user.id)s
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Contextual attributes of objects identified by their IDs are loaded
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from the database. They are also available to the policy engine and
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can be checked through the `target` keyword::
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<some_value>:%(target.role.name)s
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Finally, two special policy checks should be mentioned; the policy
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check "@" will always accept an access, and the policy check "!" will
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always reject an access. (Note that if a rule is either the empty
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list ("[]") or the empty string, this is equivalent to the "@" policy
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check.) Of these, the "!" policy check is probably the most useful,
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as it allows particular rules to be explicitly disabled.
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"""
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import abc
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import ast
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import copy
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import logging
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import os
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import re
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from oslo.config import cfg
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from oslo.serialization import jsonutils
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import six
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import six.moves.urllib.parse as urlparse
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import six.moves.urllib.request as urlrequest
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from ceilometer.openstack.common import fileutils
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from ceilometer.openstack.common._i18n import _, _LE, _LI
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policy_opts = [
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cfg.StrOpt('policy_file',
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default='policy.json',
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help=_('The JSON file that defines policies.')),
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cfg.StrOpt('policy_default_rule',
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default='default',
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help=_('Default rule. Enforced when a requested rule is not '
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'found.')),
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cfg.MultiStrOpt('policy_dirs',
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default=['policy.d'],
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help=_('Directories where policy configuration files are '
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'stored. They can be relative to any directory '
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'in the search path defined by the config_dir '
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'option, or absolute paths. The file defined by '
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'policy_file must exist for these directories to '
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'be searched.')),
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]
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CONF = cfg.CONF
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CONF.register_opts(policy_opts)
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LOG = logging.getLogger(__name__)
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_checks = {}
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def list_opts():
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"""Entry point for oslo.config-generator."""
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return [(None, copy.deepcopy(policy_opts))]
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class PolicyNotAuthorized(Exception):
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def __init__(self, rule):
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msg = _("Policy doesn't allow %s to be performed.") % rule
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super(PolicyNotAuthorized, self).__init__(msg)
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class Rules(dict):
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"""A store for rules. Handles the default_rule setting directly."""
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@classmethod
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def load_json(cls, data, default_rule=None):
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"""Allow loading of JSON rule data."""
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# Suck in the JSON data and parse the rules
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rules = dict((k, parse_rule(v)) for k, v in
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jsonutils.loads(data).items())
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return cls(rules, default_rule)
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def __init__(self, rules=None, default_rule=None):
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"""Initialize the Rules store."""
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super(Rules, self).__init__(rules or {})
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self.default_rule = default_rule
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def __missing__(self, key):
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"""Implements the default rule handling."""
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if isinstance(self.default_rule, dict):
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raise KeyError(key)
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# If the default rule isn't actually defined, do something
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# reasonably intelligent
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if not self.default_rule:
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raise KeyError(key)
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if isinstance(self.default_rule, BaseCheck):
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return self.default_rule
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# We need to check this or we can get infinite recursion
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if self.default_rule not in self:
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raise KeyError(key)
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elif isinstance(self.default_rule, six.string_types):
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return self[self.default_rule]
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def __str__(self):
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"""Dumps a string representation of the rules."""
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# Start by building the canonical strings for the rules
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out_rules = {}
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for key, value in self.items():
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# Use empty string for singleton TrueCheck instances
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if isinstance(value, TrueCheck):
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out_rules[key] = ''
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else:
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out_rules[key] = str(value)
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# Dump a pretty-printed JSON representation
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return jsonutils.dumps(out_rules, indent=4)
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class Enforcer(object):
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"""Responsible for loading and enforcing rules.
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:param policy_file: Custom policy file to use, if none is
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specified, `CONF.policy_file` will be
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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. If
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`load_rules(True)`, `clear()` or `set_rules(True)`
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is called this will be overwritten.
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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 cache or config file.
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:param overwrite: Whether to overwrite existing rules when reload rules
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from config file.
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"""
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def __init__(self, policy_file=None, rules=None,
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default_rule=None, use_conf=True, overwrite=True):
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self.default_rule = default_rule or CONF.policy_default_rule
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self.rules = Rules(rules, self.default_rule)
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self.policy_path = None
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self.policy_file = policy_file or CONF.policy_file
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self.use_conf = use_conf
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self.overwrite = overwrite
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def set_rules(self, rules, overwrite=True, use_conf=False):
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"""Create a new Rules object 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 cache or config file.
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"""
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if not isinstance(rules, dict):
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raise TypeError(_("Rules must be an instance of dict or Rules, "
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"got %s instead") % type(rules))
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self.use_conf = use_conf
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if overwrite:
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self.rules = Rules(rules, self.default_rule)
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else:
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self.rules.update(rules)
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def clear(self):
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"""Clears Enforcer rules, policy's cache and policy's path."""
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self.set_rules({})
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fileutils.delete_cached_file(self.policy_path)
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self.default_rule = None
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self.policy_path = None
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def load_rules(self, force_reload=False):
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"""Loads policy_path's rules.
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Policy file is cached and will be reloaded if modified.
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:param force_reload: Whether to reload rules from config file.
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"""
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if force_reload:
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self.use_conf = force_reload
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if self.use_conf:
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if not self.policy_path:
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self.policy_path = self._get_policy_path(self.policy_file)
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self._load_policy_file(self.policy_path, force_reload,
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overwrite=self.overwrite)
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for path in CONF.policy_dirs:
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try:
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path = self._get_policy_path(path)
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except cfg.ConfigFilesNotFoundError:
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LOG.info(_LI("Can not find policy directory: %s"), path)
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continue
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self._walk_through_policy_directory(path,
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self._load_policy_file,
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force_reload, False)
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@staticmethod
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def _walk_through_policy_directory(path, func, *args):
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# We do not iterate over sub-directories.
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policy_files = next(os.walk(path))[2]
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policy_files.sort()
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for policy_file in [p for p in policy_files if not p.startswith('.')]:
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func(os.path.join(path, policy_file), *args)
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def _load_policy_file(self, path, force_reload, overwrite=True):
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reloaded, data = fileutils.read_cached_file(
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path, force_reload=force_reload)
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if reloaded or not self.rules or not overwrite:
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rules = Rules.load_json(data, self.default_rule)
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self.set_rules(rules, overwrite=overwrite, use_conf=True)
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LOG.debug("Rules successfully reloaded")
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def _get_policy_path(self, path):
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"""Locate the policy json data file/path.
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:param path: It's value can be a full path or related path. When
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full path specified, this function just returns the full
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path. When related path specified, this function will
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search configuration directories to find one that exists.
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:returns: The policy path
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:raises: ConfigFilesNotFoundError if the file/path couldn't
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be located.
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"""
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policy_path = CONF.find_file(path)
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if policy_path:
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return policy_path
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raise cfg.ConfigFilesNotFoundError((path,))
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def enforce(self, rule, target, creds, do_raise=False,
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exc=None, *args, **kwargs):
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"""Checks authorization of a rule against the target and credentials.
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:param rule: A string or BaseCheck instance specifying the rule
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to evaluate.
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:param target: As much information about the object being operated
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on as possible, as a dictionary.
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:param creds: As much information about the user performing the
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action as possible, as a dictionary.
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:param do_raise: Whether to raise an exception or not if check
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fails.
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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 enforce() (both
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positional and keyword arguments) will be passed to
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the exception class. If not specified, PolicyNotAuthorized
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|
will be used.
|
|
|
|
|
|
|
|
|
|
:return: Returns False if the policy does not allow the action and
|
|
|
|
|
exc is not provided; otherwise, returns a value that
|
|
|
|
|
evaluates to True. Note: for rules using the "case"
|
|
|
|
|
expression, this True value will be the specified string
|
|
|
|
|
from the expression.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.load_rules()
|
|
|
|
|
|
|
|
|
|
# Allow the rule to be a Check tree
|
|
|
|
|
if isinstance(rule, BaseCheck):
|
|
|
|
|
result = rule(target, creds, self)
|
|
|
|
|
elif not self.rules:
|
|
|
|
|
# No rules to reference means we're going to fail closed
|
|
|
|
|
result = False
|
|
|
|
|
else:
|
|
|
|
|
try:
|
|
|
|
|
# Evaluate the rule
|
|
|
|
|
result = self.rules[rule](target, creds, self)
|
|
|
|
|
except KeyError:
|
|
|
|
|
LOG.debug("Rule [%s] doesn't exist" % rule)
|
|
|
|
|
# If the rule doesn't exist, fail closed
|
|
|
|
|
result = False
|
|
|
|
|
|
|
|
|
|
# If it is False, raise the exception if requested
|
|
|
|
|
if do_raise and not result:
|
|
|
|
|
if exc:
|
|
|
|
|
raise exc(*args, **kwargs)
|
|
|
|
|
|
|
|
|
|
raise PolicyNotAuthorized(rule)
|
|
|
|
|
|
|
|
|
|
return result
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
|
|
|
class BaseCheck(object):
|
|
|
|
|
"""Abstract base class for Check classes."""
|
|
|
|
|
|
|
|
|
|
@abc.abstractmethod
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""String representation of the Check tree rooted at this node."""
|
|
|
|
|
|
|
|
|
|
pass
|
|
|
|
|
|
|
|
|
|
@abc.abstractmethod
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Triggers if instance of the class is called.
|
|
|
|
|
|
|
|
|
|
Performs the check. Returns False to reject the access or a
|
|
|
|
|
true value (not necessary True) to accept the access.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
pass
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class FalseCheck(BaseCheck):
|
|
|
|
|
"""A policy check that always returns False (disallow)."""
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "!"
|
|
|
|
|
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Check the policy."""
|
|
|
|
|
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class TrueCheck(BaseCheck):
|
|
|
|
|
"""A policy check that always returns True (allow)."""
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "@"
|
|
|
|
|
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Check the policy."""
|
|
|
|
|
|
|
|
|
|
return True
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class Check(BaseCheck):
|
|
|
|
|
"""A base class to allow for user-defined policy checks."""
|
|
|
|
|
|
|
|
|
|
def __init__(self, kind, match):
|
|
|
|
|
"""Initiates Check instance.
|
|
|
|
|
|
|
|
|
|
:param kind: The kind of the check, i.e., the field before the
|
|
|
|
|
':'.
|
|
|
|
|
:param match: The match of the check, i.e., the field after
|
|
|
|
|
the ':'.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.kind = kind
|
|
|
|
|
self.match = match
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "%s:%s" % (self.kind, self.match)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class NotCheck(BaseCheck):
|
|
|
|
|
"""Implements the "not" logical operator.
|
|
|
|
|
|
|
|
|
|
A policy check that inverts the result of another policy check.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def __init__(self, rule):
|
|
|
|
|
"""Initialize the 'not' check.
|
|
|
|
|
|
|
|
|
|
:param rule: The rule to negate. Must be a Check.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.rule = rule
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "not %s" % self.rule
|
|
|
|
|
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Check the policy.
|
|
|
|
|
|
|
|
|
|
Returns the logical inverse of the wrapped check.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
return not self.rule(target, cred, enforcer)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class AndCheck(BaseCheck):
|
|
|
|
|
"""Implements the "and" logical operator.
|
|
|
|
|
|
|
|
|
|
A policy check that requires that a list of other checks all return True.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def __init__(self, rules):
|
|
|
|
|
"""Initialize the 'and' check.
|
|
|
|
|
|
|
|
|
|
:param rules: A list of rules that will be tested.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.rules = rules
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "(%s)" % ' and '.join(str(r) for r in self.rules)
|
|
|
|
|
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Check the policy.
|
|
|
|
|
|
|
|
|
|
Requires that all rules accept in order to return True.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
for rule in self.rules:
|
|
|
|
|
if not rule(target, cred, enforcer):
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
return True
|
|
|
|
|
|
|
|
|
|
def add_check(self, rule):
|
|
|
|
|
"""Adds rule to be tested.
|
|
|
|
|
|
|
|
|
|
Allows addition of another rule to the list of rules that will
|
|
|
|
|
be tested. Returns the AndCheck object for convenience.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.rules.append(rule)
|
|
|
|
|
return self
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class OrCheck(BaseCheck):
|
|
|
|
|
"""Implements the "or" operator.
|
|
|
|
|
|
|
|
|
|
A policy check that requires that at least one of a list of other
|
|
|
|
|
checks returns True.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def __init__(self, rules):
|
|
|
|
|
"""Initialize the 'or' check.
|
|
|
|
|
|
|
|
|
|
:param rules: A list of rules that will be tested.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.rules = rules
|
|
|
|
|
|
|
|
|
|
def __str__(self):
|
|
|
|
|
"""Return a string representation of this check."""
|
|
|
|
|
|
|
|
|
|
return "(%s)" % ' or '.join(str(r) for r in self.rules)
|
|
|
|
|
|
|
|
|
|
def __call__(self, target, cred, enforcer):
|
|
|
|
|
"""Check the policy.
|
|
|
|
|
|
|
|
|
|
Requires that at least one rule accept in order to return True.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
for rule in self.rules:
|
|
|
|
|
if rule(target, cred, enforcer):
|
|
|
|
|
return True
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
def add_check(self, rule):
|
|
|
|
|
"""Adds rule to be tested.
|
|
|
|
|
|
|
|
|
|
Allows addition of another rule to the list of rules that will
|
|
|
|
|
be tested. Returns the OrCheck object for convenience.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
self.rules.append(rule)
|
|
|
|
|
return self
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def _parse_check(rule):
|
|
|
|
|
"""Parse a single base check rule into an appropriate Check object."""
|
|
|
|
|
|
|
|
|
|
# Handle the special checks
|
|
|
|
|
if rule == '!':
|
|
|
|
|
return FalseCheck()
|
|
|
|
|
elif rule == '@':
|
|
|
|
|
return TrueCheck()
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
kind, match = rule.split(':', 1)
|
|
|
|
|
except Exception:
|
|
|
|
|
LOG.exception(_LE("Failed to understand rule %s") % rule)
|
|
|
|
|
# If the rule is invalid, we'll fail closed
|
|
|
|
|
return FalseCheck()
|
|
|
|
|
|
|
|
|
|
# Find what implements the check
|
|
|
|
|
if kind in _checks:
|
|
|
|
|
return _checks[kind](kind, match)
|
|
|
|
|
elif None in _checks:
|
|
|
|
|
return _checks[None](kind, match)
|
|
|
|
|
else:
|
|
|
|
|
LOG.error(_LE("No handler for matches of kind %s") % kind)
|
|
|
|
|
return FalseCheck()
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def _parse_list_rule(rule):
|
|
|
|
|
"""Translates the old list-of-lists syntax into a tree of Check objects.
|
|
|
|
|
|
|
|
|
|
Provided for backwards compatibility.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
# Empty rule defaults to True
|
|
|
|
|
if not rule:
|
|
|
|
|
return TrueCheck()
|
|
|
|
|
|
|
|
|
|
# Outer list is joined by "or"; inner list by "and"
|
|
|
|
|
or_list = []
|
|
|
|
|
for inner_rule in rule:
|
|
|
|
|
# Elide empty inner lists
|
|
|
|
|
if not inner_rule:
|
|
|
|
|
continue
|
|
|
|
|
|
|
|
|
|
# Handle bare strings
|
|
|
|
|
if isinstance(inner_rule, six.string_types):
|
|
|
|
|
inner_rule = [inner_rule]
|
|
|
|
|
|
|
|
|
|
# Parse the inner rules into Check objects
|
|
|
|
|
and_list = [_parse_check(r) for r in inner_rule]
|
|
|
|
|
|
|
|
|
|
# Append the appropriate check to the or_list
|
|
|
|
|
if len(and_list) == 1:
|
|
|
|
|
or_list.append(and_list[0])
|
|
|
|
|
else:
|
|
|
|
|
or_list.append(AndCheck(and_list))
|
|
|
|
|
|
|
|
|
|
# If we have only one check, omit the "or"
|
|
|
|
|
if not or_list:
|
|
|
|
|
return FalseCheck()
|
|
|
|
|
elif len(or_list) == 1:
|
|
|
|
|
return or_list[0]
|
|
|
|
|
|
|
|
|
|
return OrCheck(or_list)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
# Used for tokenizing the policy language
|
|
|
|
|
_tokenize_re = re.compile(r'\s+')
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def _parse_tokenize(rule):
|
|
|
|
|
"""Tokenizer for the policy language.
|
|
|
|
|
|
|
|
|
|
Most of the single-character tokens are specified in the
|
|
|
|
|
_tokenize_re; however, parentheses need to be handled specially,
|
|
|
|
|
because they can appear inside a check string. Thankfully, those
|
|
|
|
|
parentheses that appear inside a check string can never occur at
|
|
|
|
|
the very beginning or end ("%(variable)s" is the correct syntax).
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
for tok in _tokenize_re.split(rule):
|
|
|
|
|
# Skip empty tokens
|
|
|
|
|
if not tok or tok.isspace():
|
|
|
|
|
continue
|
|
|
|
|
|
|
|
|
|
# Handle leading parens on the token
|
|
|
|
|
clean = tok.lstrip('(')
|
|
|
|
|
for i in range(len(tok) - len(clean)):
|
|
|
|
|
yield '(', '('
|
|
|
|
|
|
|
|
|
|
# If it was only parentheses, continue
|
|
|
|
|
if not clean:
|
|
|
|
|
continue
|
|
|
|
|
else:
|
|
|
|
|
tok = clean
|
|
|
|
|
|
|
|
|
|
# Handle trailing parens on the token
|
|
|
|
|
clean = tok.rstrip(')')
|
|
|
|
|
trail = len(tok) - len(clean)
|
|
|
|
|
|
|
|
|
|
# Yield the cleaned token
|
|
|
|
|
lowered = clean.lower()
|
|
|
|
|
if lowered in ('and', 'or', 'not'):
|
|
|
|
|
# Special tokens
|
|
|
|
|
yield lowered, clean
|
|
|
|
|
elif clean:
|
|
|
|
|
# Not a special token, but not composed solely of ')'
|
|
|
|
|
if len(tok) >= 2 and ((tok[0], tok[-1]) in
|
|
|
|
|
[('"', '"'), ("'", "'")]):
|
|
|
|
|
# It's a quoted string
|
|
|
|
|
yield 'string', tok[1:-1]
|
|
|
|
|
else:
|
|
|
|
|
yield 'check', _parse_check(clean)
|
|
|
|
|
|
|
|
|
|
# Yield the trailing parens
|
|
|
|
|
for i in range(trail):
|
|
|
|
|
yield ')', ')'
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
class ParseStateMeta(type):
|
|
|
|
|
"""Metaclass for the ParseState class.
|
|
|
|
|
|
|
|
|
|
Facilitates identifying reduction methods.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def __new__(mcs, name, bases, cls_dict):
|
|
|
|
|
"""Create the class.
|
|
|
|
|
|
|
|
|
|
Injects the 'reducers' list, a list of tuples matching token sequences
|
|
|
|
|
to the names of the corresponding reduction methods.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
reducers = []
|
|
|
|
|
|
|
|
|
|
for key, value in cls_dict.items():
|
|
|
|
|
if not hasattr(value, 'reducers'):
|
|
|
|
|
continue
|
|
|
|
|
for reduction in value.reducers:
|
|
|
|
|
reducers.append((reduction, key))
|
|
|
|
|
|
|
|
|
|
cls_dict['reducers'] = reducers
|
|
|
|
|
|
|
|
|
|
return super(ParseStateMeta, mcs).__new__(mcs, name, bases, cls_dict)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def reducer(*tokens):
|
|
|
|
|
"""Decorator for reduction methods.
|
|
|
|
|
|
|
|
|
|
Arguments are a sequence of tokens, in order, which should trigger running
|
|
|
|
|
this reduction method.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
def decorator(func):
|
|
|
|
|
# Make sure we have a list of reducer sequences
|
|
|
|
|
if not hasattr(func, 'reducers'):
|
|
|
|
|
func.reducers = []
|
|
|
|
|
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|
|
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|
# Add the tokens to the list of reducer sequences
|
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|
func.reducers.append(list(tokens))
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|
return func
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|
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|
|
|
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|
return decorator
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|
@six.add_metaclass(ParseStateMeta)
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|
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|
class ParseState(object):
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|
"""Implement the core of parsing the policy language.
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|
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|
Uses a greedy reduction algorithm to reduce a sequence of tokens into
|
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|
a single terminal, the value of which will be the root of the Check tree.
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|
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|
Note: error reporting is rather lacking. The best we can get with
|
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|
this parser formulation is an overall "parse failed" error.
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|
|
|
Fortunately, the policy language is simple enough that this
|
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|
|
shouldn't be that big a problem.
|
|
|
|
|
"""
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|
|
|
|
|
|
|
def __init__(self):
|
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|
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|
"""Initialize the ParseState."""
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|
self.tokens = []
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|
self.values = []
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|
|
def reduce(self):
|
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|
"""Perform a greedy reduction of the token stream.
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|
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|
If a reducer method matches, it will be executed, then the
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|
reduce() method will be called recursively to search for any more
|
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|
possible reductions.
|
|
|
|
|
"""
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|
|
|
for reduction, methname in self.reducers:
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|
if (len(self.tokens) >= len(reduction) and
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|
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|
|
self.tokens[-len(reduction):] == reduction):
|
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|
|
# Get the reduction method
|
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|
|
meth = getattr(self, methname)
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|
|
# Reduce the token stream
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|
|
results = meth(*self.values[-len(reduction):])
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|
|
# Update the tokens and values
|
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|
|
self.tokens[-len(reduction):] = [r[0] for r in results]
|
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|
|
self.values[-len(reduction):] = [r[1] for r in results]
|
|
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|
|
|
|
|
|
|
# Check for any more reductions
|
|
|
|
|
return self.reduce()
|
|
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|
|
|
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|
|
def shift(self, tok, value):
|
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|
|
|
"""Adds one more token to the state. Calls reduce()."""
|
|
|
|
|
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|
|
|
self.tokens.append(tok)
|
|
|
|
|
self.values.append(value)
|
|
|
|
|
|
|
|
|
|
# Do a greedy reduce...
|
|
|
|
|
self.reduce()
|
|
|
|
|
|
|
|
|
|
@property
|
|
|
|
|
def result(self):
|
|
|
|
|
"""Obtain the final result of the parse.
|
|
|
|
|
|
|
|
|
|
Raises ValueError if the parse failed to reduce to a single result.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
if len(self.values) != 1:
|
|
|
|
|
raise ValueError("Could not parse rule")
|
|
|
|
|
return self.values[0]
|
|
|
|
|
|
|
|
|
|
@reducer('(', 'check', ')')
|
|
|
|
|
@reducer('(', 'and_expr', ')')
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|
|
@reducer('(', 'or_expr', ')')
|
|
|
|
|
def _wrap_check(self, _p1, check, _p2):
|
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|
|
|
"""Turn parenthesized expressions into a 'check' token."""
|
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|
|
return [('check', check)]
|
|
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|
|
|
|
|
|
|
@reducer('check', 'and', 'check')
|
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|
|
|
def _make_and_expr(self, check1, _and, check2):
|
|
|
|
|
"""Create an 'and_expr'.
|
|
|
|
|
|
|
|
|
|
Join two checks by the 'and' operator.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
return [('and_expr', AndCheck([check1, check2]))]
|
|
|
|
|
|
|
|
|
|
@reducer('and_expr', 'and', 'check')
|
|
|
|
|
def _extend_and_expr(self, and_expr, _and, check):
|
|
|
|
|
"""Extend an 'and_expr' by adding one more check."""
|
|
|
|
|
|
|
|
|
|
return [('and_expr', and_expr.add_check(check))]
|
|
|
|
|
|
|
|
|
|
@reducer('check', 'or', 'check')
|
|
|
|
|
def _make_or_expr(self, check1, _or, check2):
|
|
|
|
|
"""Create an 'or_expr'.
|
|
|
|
|
|
|
|
|
|
Join two checks by the 'or' operator.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
return [('or_expr', OrCheck([check1, check2]))]
|
|
|
|
|
|
|
|
|
|
@reducer('or_expr', 'or', 'check')
|
|
|
|
|
def _extend_or_expr(self, or_expr, _or, check):
|
|
|
|
|
"""Extend an 'or_expr' by adding one more check."""
|
|
|
|
|
|
|
|
|
|
return [('or_expr', or_expr.add_check(check))]
|
|
|
|
|
|
|
|
|
|
@reducer('not', 'check')
|
|
|
|
|
def _make_not_expr(self, _not, check):
|
|
|
|
|
"""Invert the result of another check."""
|
|
|
|
|
|
|
|
|
|
return [('check', NotCheck(check))]
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def _parse_text_rule(rule):
|
|
|
|
|
"""Parses policy to the tree.
|
|
|
|
|
|
|
|
|
|
Translates a policy written in the policy language into a tree of
|
|
|
|
|
Check objects.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
# Empty rule means always accept
|
|
|
|
|
if not rule:
|
|
|
|
|
return TrueCheck()
|
|
|
|
|
|
|
|
|
|
# Parse the token stream
|
|
|
|
|
state = ParseState()
|
|
|
|
|
for tok, value in _parse_tokenize(rule):
|
|
|
|
|
state.shift(tok, value)
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
return state.result
|
|
|
|
|
except ValueError:
|
|
|
|
|
# Couldn't parse the rule
|
|
|
|
|
LOG.exception(_LE("Failed to understand rule %s") % rule)
|
|
|
|
|
|
|
|
|
|
# Fail closed
|
|
|
|
|
return FalseCheck()
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def parse_rule(rule):
|
|
|
|
|
"""Parses a policy rule into a tree of Check objects."""
|
|
|
|
|
|
|
|
|
|
# If the rule is a string, it's in the policy language
|
|
|
|
|
if isinstance(rule, six.string_types):
|
|
|
|
|
return _parse_text_rule(rule)
|
|
|
|
|
return _parse_list_rule(rule)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
def register(name, func=None):
|
|
|
|
|
"""Register a function or Check class as a policy check.
|
|
|
|
|
|
|
|
|
|
:param name: Gives the name of the check type, e.g., 'rule',
|
|
|
|
|
'role', etc. If name is None, a default check type
|
|
|
|
|
will be registered.
|
|
|
|
|
:param func: If given, provides the function or class to register.
|
|
|
|
|
If not given, returns a function taking one argument
|
|
|
|
|
to specify the function or class to register,
|
|
|
|
|
allowing use as a decorator.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
# Perform the actual decoration by registering the function or
|
|
|
|
|
# class. Returns the function or class for compliance with the
|
|
|
|
|
# decorator interface.
|
|
|
|
|
def decorator(func):
|
|
|
|
|
_checks[name] = func
|
|
|
|
|
return func
|
|
|
|
|
|
|
|
|
|
# If the function or class is given, do the registration
|
|
|
|
|
if func:
|
|
|
|
|
return decorator(func)
|
|
|
|
|
|
|
|
|
|
return decorator
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@register("rule")
|
|
|
|
|
class RuleCheck(Check):
|
|
|
|
|
def __call__(self, target, creds, enforcer):
|
|
|
|
|
"""Recursively checks credentials based on the defined rules."""
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
return enforcer.rules[self.match](target, creds, enforcer)
|
|
|
|
|
except KeyError:
|
|
|
|
|
# We don't have any matching rule; fail closed
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@register("role")
|
|
|
|
|
class RoleCheck(Check):
|
|
|
|
|
def __call__(self, target, creds, enforcer):
|
|
|
|
|
"""Check that there is a matching role in the cred dict."""
|
|
|
|
|
|
|
|
|
|
return self.match.lower() in [x.lower() for x in creds['roles']]
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@register('http')
|
|
|
|
|
class HttpCheck(Check):
|
|
|
|
|
def __call__(self, target, creds, enforcer):
|
|
|
|
|
"""Check http: rules by calling to a remote server.
|
|
|
|
|
|
|
|
|
|
This example implementation simply verifies that the response
|
|
|
|
|
is exactly 'True'.
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
url = ('http:' + self.match) % target
|
|
|
|
|
|
|
|
|
|
# Convert instances of object() in target temporarily to
|
|
|
|
|
# empty dict to avoid circular reference detection
|
|
|
|
|
# errors in jsonutils.dumps().
|
|
|
|
|
temp_target = copy.deepcopy(target)
|
|
|
|
|
for key in target.keys():
|
|
|
|
|
element = target.get(key)
|
|
|
|
|
if type(element) is object:
|
|
|
|
|
temp_target[key] = {}
|
|
|
|
|
|
|
|
|
|
data = {'target': jsonutils.dumps(temp_target),
|
|
|
|
|
'credentials': jsonutils.dumps(creds)}
|
|
|
|
|
post_data = urlparse.urlencode(data)
|
|
|
|
|
f = urlrequest.urlopen(url, post_data)
|
|
|
|
|
return f.read() == "True"
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
@register(None)
|
|
|
|
|
class GenericCheck(Check):
|
|
|
|
|
def __call__(self, target, creds, enforcer):
|
|
|
|
|
"""Check an individual match.
|
|
|
|
|
|
|
|
|
|
Matches look like:
|
|
|
|
|
|
|
|
|
|
tenant:%(tenant_id)s
|
|
|
|
|
role:compute:admin
|
|
|
|
|
True:%(user.enabled)s
|
|
|
|
|
'Member':%(role.name)s
|
|
|
|
|
"""
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
match = self.match % target
|
|
|
|
|
except KeyError:
|
|
|
|
|
# While doing GenericCheck if key not
|
|
|
|
|
# present in Target return false
|
|
|
|
|
return False
|
|
|
|
|
|
|
|
|
|
try:
|
|
|
|
|
# Try to interpret self.kind as a literal
|
|
|
|
|
leftval = ast.literal_eval(self.kind)
|
|
|
|
|
except ValueError:
|
|
|
|
|
try:
|
|
|
|
|
kind_parts = self.kind.split('.')
|
|
|
|
|
leftval = creds
|
|
|
|
|
for kind_part in kind_parts:
|
|
|
|
|
leftval = leftval[kind_part]
|
|
|
|
|
except KeyError:
|
|
|
|
|
return False
|
|
|
|
|
return match == six.text_type(leftval)
|
Jenkins