"""passbook core policy engine""" from logging import getLogger from amqp.exceptions import UnexpectedFrame from celery import group from celery.exceptions import TimeoutError as CeleryTimeoutError from django.core.cache import cache from ipware import get_client_ip from passbook.core.celery import CELERY_APP from passbook.core.models import Policy, User LOGGER = getLogger(__name__) def _cache_key(policy, user): return "policy_%s#%s" % (policy.uuid, user.pk) @CELERY_APP.task() def _policy_engine_task(user_pk, policy_pk, **kwargs): """Task wrapper to run policy checking""" if not user_pk: raise ValueError() policy_obj = Policy.objects.filter(pk=policy_pk).select_subclasses().first() user_obj = User.objects.get(pk=user_pk) for key, value in kwargs.items(): setattr(user_obj, key, value) LOGGER.debug("Running policy `%s`#%s for user %s...", policy_obj.name, policy_obj.pk.hex, user_obj) policy_result = policy_obj.passes(user_obj) # Handle policy result correctly if result, message or just result message = None if isinstance(policy_result, (tuple, list)): policy_result, message = policy_result # Invert result if policy.negate is set if policy_obj.negate: policy_result = not policy_result LOGGER.debug("Policy %r#%s got %s", policy_obj.name, policy_obj.pk.hex, policy_result) cache_key = _cache_key(policy_obj, user_obj) cache.set(cache_key, (policy_obj.action, policy_result, message)) LOGGER.debug("Cached entry as %s", cache_key) return policy_obj.action, policy_result, message class PolicyEngine: """Orchestrate policy checking, launch tasks and return result""" __group = None __cached = None policies = None __get_timeout = 0 __request = None __user = None def __init__(self, policies): self.policies = policies self.__request = None self.__user = None def for_user(self, user): """Check policies for user""" self.__user = user return self def with_request(self, request): """Set request""" self.__request = request return self def build(self): """Build task group""" if not self.__user: raise ValueError("User not set.") signatures = [] cached_policies = [] kwargs = { '__password__': getattr(self.__user, '__password__', None), } if self.__request: kwargs['remote_ip'], _ = get_client_ip(self.__request) if not kwargs['remote_ip']: kwargs['remote_ip'] = '255.255.255.255' for policy in self.policies: cached_policy = cache.get(_cache_key(policy, self.__user), None) if cached_policy: LOGGER.debug("Taking result from cache for %s", policy.pk.hex) cached_policies.append(cached_policy) else: LOGGER.debug("Evaluating policy %s", policy.pk.hex) signatures.append(_policy_engine_task.signature( args=(self.__user.pk, policy.pk.hex), kwargs=kwargs, time_limit=policy.timeout)) self.__get_timeout += policy.timeout LOGGER.debug("Set total policy timeout to %r", self.__get_timeout) # If all policies are cached, we have an empty list here. if signatures: self.__group = group(signatures)() self.__get_timeout += 3 self.__get_timeout = (self.__get_timeout / len(self.policies)) * 1.5 self.__cached = cached_policies return self @property def result(self): """Get policy-checking result""" messages = [] result = [] try: if self.__group: # ValueError can be thrown from _policy_engine_task when user is None result += self.__group.get(timeout=self.__get_timeout) result += self.__cached except ValueError as exc: # ValueError can be thrown from _policy_engine_task when user is None return False, [str(exc)] except UnexpectedFrame as exc: return False, [str(exc)] except CeleryTimeoutError as exc: return False, [str(exc)] for policy_action, policy_result, policy_message in result: passing = (policy_action == Policy.ACTION_ALLOW and policy_result) or \ (policy_action == Policy.ACTION_DENY and not policy_result) LOGGER.debug('Action=%s, Result=%r => %r', policy_action, policy_result, passing) if policy_message: messages.append(policy_message) if not passing: return False, messages return True, messages @property def passing(self): """Only get true/false if user passes""" return self.result[0]