/usr/lib/python2.7/dist-packages/nova/policy.py is in python-nova 2:17.0.1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
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# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Policy Engine For Nova."""
import copy
import re
import sys
from oslo_config import cfg
from oslo_log import log as logging
from oslo_policy import policy
from oslo_utils import excutils
from nova import exception
from nova.i18n import _LE, _LW
from nova import policies
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
_ENFORCER = None
# This list is about the resources which support user based policy enforcement.
# Avoid sending deprecation warning for those resources.
USER_BASED_RESOURCES = ['os-keypairs']
# oslo_policy will read the policy configuration file again when the file
# is changed in runtime so the old policy rules will be saved to
# saved_file_rules and used to compare with new rules to determine the
# rules whether were updated.
saved_file_rules = []
KEY_EXPR = re.compile(r'%\((\w+)\)s')
def reset():
global _ENFORCER
if _ENFORCER:
_ENFORCER.clear()
_ENFORCER = None
def init(policy_file=None, rules=None, default_rule=None, use_conf=True):
"""Init an Enforcer class.
:param policy_file: Custom policy file to use, if none is specified,
`CONF.policy_file` will be used.
:param rules: Default dictionary / Rules to use. It will be
considered just in the first instantiation.
:param default_rule: Default rule to use, CONF.default_rule will
be used if none is specified.
:param use_conf: Whether to load rules from config file.
"""
global _ENFORCER
global saved_file_rules
if not _ENFORCER:
_ENFORCER = policy.Enforcer(CONF,
policy_file=policy_file,
rules=rules,
default_rule=default_rule,
use_conf=use_conf)
register_rules(_ENFORCER)
_ENFORCER.load_rules()
# Only the rules which are loaded from file may be changed.
current_file_rules = _ENFORCER.file_rules
current_file_rules = _serialize_rules(current_file_rules)
# Checks whether the rules are updated in the runtime
if saved_file_rules != current_file_rules:
_warning_for_deprecated_user_based_rules(current_file_rules)
saved_file_rules = copy.deepcopy(current_file_rules)
def _serialize_rules(rules):
"""Serialize all the Rule object as string which is used to compare the
rules list.
"""
result = [(rule_name, str(rule))
for rule_name, rule in rules.items()]
return sorted(result, key=lambda rule: rule[0])
def _warning_for_deprecated_user_based_rules(rules):
"""Warning user based policy enforcement used in the rule but the rule
doesn't support it.
"""
for rule in rules:
# We will skip the warning for the resources which support user based
# policy enforcement.
if [resource for resource in USER_BASED_RESOURCES
if resource in rule[0]]:
continue
if 'user_id' in KEY_EXPR.findall(rule[1]):
LOG.warning(_LW("The user_id attribute isn't supported in the "
"rule '%s'. All the user_id based policy "
"enforcement will be removed in the "
"future."), rule[0])
def set_rules(rules, overwrite=True, use_conf=False):
"""Set rules based on the provided dict of rules.
:param rules: New rules to use. It should be an instance of dict.
:param overwrite: Whether to overwrite current rules or update them
with the new rules.
:param use_conf: Whether to reload rules from config file.
"""
init(use_conf=False)
_ENFORCER.set_rules(rules, overwrite, use_conf)
def authorize(context, action, target, do_raise=True, exc=None):
"""Verifies that the action is valid on the target in this context.
:param context: nova context
:param action: string representing the action to be checked
this should be colon separated for clarity.
i.e. ``compute:create_instance``,
``compute:attach_volume``,
``volume:attach_volume``
:param target: dictionary representing the object of the action
for object creation this should be a dictionary representing the
location of the object e.g. ``{'project_id': context.project_id}``
:param do_raise: if True (the default), raises PolicyNotAuthorized;
if False, returns False
:param exc: Class of the exception to raise if the check fails.
Any remaining arguments passed to :meth:`authorize` (both
positional and keyword arguments) will be passed to
the exception class. If not specified,
:class:`PolicyNotAuthorized` will be used.
:raises nova.exception.PolicyNotAuthorized: if verification fails
and do_raise is True. Or if 'exc' is specified it will raise an
exception of that type.
:return: returns a non-False value (not necessarily "True") if
authorized, and the exact value False if not authorized and
do_raise is False.
"""
init()
credentials = context.to_policy_values()
if not exc:
exc = exception.PolicyNotAuthorized
try:
result = _ENFORCER.authorize(action, target, credentials,
do_raise=do_raise, exc=exc, action=action)
except policy.PolicyNotRegistered:
with excutils.save_and_reraise_exception():
LOG.exception(_LE('Policy not registered'))
except Exception:
with excutils.save_and_reraise_exception():
LOG.debug('Policy check for %(action)s failed with credentials '
'%(credentials)s',
{'action': action, 'credentials': credentials})
return result
def check_is_admin(context):
"""Whether or not roles contains 'admin' role according to policy setting.
"""
init()
# the target is user-self
credentials = context.to_policy_values()
target = credentials
return _ENFORCER.authorize('context_is_admin', target, credentials)
@policy.register('is_admin')
class IsAdminCheck(policy.Check):
"""An explicit check for is_admin."""
def __init__(self, kind, match):
"""Initialize the check."""
self.expected = (match.lower() == 'true')
super(IsAdminCheck, self).__init__(kind, str(self.expected))
def __call__(self, target, creds, enforcer):
"""Determine whether is_admin matches the requested value."""
return creds['is_admin'] == self.expected
def get_rules():
if _ENFORCER:
return _ENFORCER.rules
def register_rules(enforcer):
enforcer.register_defaults(policies.list_rules())
def get_enforcer():
# This method is for use by oslopolicy CLI scripts. Those scripts need the
# 'output-file' and 'namespace' options, but having those in sys.argv means
# loading the Nova config options will fail as those are not expected to
# be present. So we pass in an arg list with those stripped out.
conf_args = []
# Start at 1 because cfg.CONF expects the equivalent of sys.argv[1:]
i = 1
while i < len(sys.argv):
if sys.argv[i].strip('-') in ['namespace', 'output-file']:
i += 2
continue
conf_args.append(sys.argv[i])
i += 1
cfg.CONF(conf_args, project='nova')
init()
return _ENFORCER
def verify_deprecated_policy(old_policy, new_policy, default_rule, context):
"""Check the rule of the deprecated policy action
If the current rule of the deprecated policy action is set to a non-default
value, then a warning message is logged stating that the new policy
action should be used to dictate permissions as the old policy action is
being deprecated.
:param old_policy: policy action that is being deprecated
:param new_policy: policy action that is replacing old_policy
:param default_rule: the old_policy action default rule value
:param context: the nova context
"""
if _ENFORCER:
current_rule = str(_ENFORCER.rules[old_policy])
else:
current_rule = None
if current_rule != default_rule:
LOG.warning("Start using the new action '{0}'. The existing "
"action '{1}' is being deprecated and will be "
"removed in future release.".format(new_policy,
old_policy))
context.can(old_policy)
return True
else:
return False
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