patrole_tempest_plugin/rbac_rule_validation.py

# Copyright 2017 AT&T Corporation.
# 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.

import logging

from tempest import config
from tempest.lib import exceptions
from tempest import test

from patrole_tempest_plugin import rbac_auth
from patrole_tempest_plugin import rbac_exceptions

CONF = config.CONF
LOG = logging.getLogger(__name__)


def action(service, rule, admin_only=False, expected_error_code=403):
    """A decorator which does a policy check and matches it against test run.

    A decorator which allows for positive and negative RBAC testing. Given
    an OpenStack service and a policy action enforced by that service, an
    oslo.policy lookup is performed by calling `authority.get_permission`.
    The following cases are possible:

    * If `allowed` is True and the test passes, this is a success.
    * If `allowed` is True and the test fails, this is a failure.
    * If `allowed` is False and the test passes, this is a failure.
    * If `allowed` is False and the test fails, this is a success.

    :param service: A OpenStack service: for example, "nova" or "neutron".
    :param rule: A policy action defined in a policy.json file (or in code).
    :param admin_only: Skips over oslo.policy check because the policy action
                       defined by `rule` is not enforced by the service's
                       policy enforcement logic. For example, Keystone v2
                       performs an admin check for most of its endpoints. If
                       True, `rule` is effectively ignored.
    :param expected_error_code: Overrides default value of 403 (Forbidden)
                                with endpoint-specific error code. Currently
                                only supports 403 and 404. Support for 404
                                is needed because some services, like Neutron,
                                intentionally throw a 404 for security reasons.

    :raises NotFound: if `service` is invalid or
                      if Tempest credentials cannot be found.
    :raises Forbidden: for bullet (2) above.
    :raises RbacOverPermission: for bullet (3) above.
    """
    def decorator(func):
        def wrapper(*args, **kwargs):
            try:
                caller_ref = None
                if args and isinstance(args[0], test.BaseTestCase):
                    caller_ref = args[0]
                tenant_id = caller_ref.auth_provider.credentials.tenant_id
                user_id = caller_ref.auth_provider.credentials.user_id
            except AttributeError as e:
                msg = ("{0}: tenant_id/user_id not found in "
                       "cls.auth_provider.credentials".format(e))
                LOG.error(msg)
                raise rbac_exceptions.RbacResourceSetupFailed(msg)

            if admin_only:
                LOG.info("As admin_only is True, only admin role should be "
                         "allowed to perform the API. Skipping oslo.policy "
                         "check for policy action {0}.".format(rule))
                allowed = CONF.rbac.rbac_test_role == 'admin'
            else:
                authority = rbac_auth.RbacAuthority(tenant_id, user_id,
                                                    service)
                allowed = authority.get_permission(rule,
                                                   CONF.rbac.rbac_test_role)

            expected_exception, irregular_msg = _get_exception_type(
                expected_error_code)

            try:
                func(*args)
            except rbac_exceptions.RbacInvalidService as e:
                msg = ("%s is not a valid service." % service)
                LOG.error(msg)
                raise exceptions.NotFound(
                    "%s RbacInvalidService was: %s" %
                    (msg, e))
            except expected_exception as e:
                if allowed:
                    msg = ("Role %s was not allowed to perform %s." %
                           (CONF.rbac.rbac_test_role, rule))
                    LOG.error(msg)
                    raise exceptions.Forbidden(
                        "%s exception was: %s" %
                        (msg, e))
                if irregular_msg:
                    LOG.warning(irregular_msg.format(rule, service))
            except rbac_exceptions.RbacActionFailed as e:
                if allowed:
                    msg = ("Role %s was not allowed to perform %s." %
                           (CONF.rbac.rbac_test_role, rule))
                    LOG.error(msg)
                    raise exceptions.Forbidden(
                        "%s RbacActionFailed was: %s" %
                        (msg, e))
            else:
                if not allowed:
                    LOG.error("Role %s was allowed to perform %s" %
                              (CONF.rbac.rbac_test_role, rule))
                    raise rbac_exceptions.RbacOverPermission(
                        "OverPermission: Role %s was allowed to perform %s" %
                        (CONF.rbac.rbac_test_role, rule))
            finally:
                caller_ref.rbac_utils.switch_role(caller_ref,
                                                  switchToRbacRole=False)
        return wrapper
    return decorator


def _get_exception_type(expected_error_code):
    expected_exception = None
    irregular_msg = None
    supported_error_codes = [403, 404]
    if expected_error_code == 403:
        expected_exception = exceptions.Forbidden
    elif expected_error_code == 404:
        expected_exception = exceptions.NotFound
        irregular_msg = ("NotFound exception was caught for policy action "
                         "{0}. The service {1} throws a 404 instead of a 403, "
                         "which is irregular.")
    else:
        msg = ("Please pass an expected error code. Currently "
               "supported codes: {0}".format(str(supported_error_codes)))
        LOG.error(msg)
        raise rbac_exceptions.RbacInvalidErrorCode()

    return expected_exception, irregular_msg