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