237 lines
9 KiB
Python
237 lines
9 KiB
Python
"""Flows Planner"""
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from dataclasses import dataclass, field
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from typing import Any, Optional
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from django.core.cache import cache
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from django.http import HttpRequest
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from prometheus_client import Histogram
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from sentry_sdk.hub import Hub
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from sentry_sdk.tracing import Span
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from structlog.stdlib import BoundLogger, get_logger
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from authentik.core.models import User
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from authentik.events.models import cleanse_dict
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from authentik.flows.exceptions import EmptyFlowException, FlowNonApplicableException
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from authentik.flows.markers import ReevaluateMarker, StageMarker
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from authentik.flows.models import Flow, FlowStageBinding, Stage
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from authentik.lib.config import CONFIG
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from authentik.policies.engine import PolicyEngine
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from authentik.root.monitoring import UpdatingGauge
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LOGGER = get_logger()
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PLAN_CONTEXT_PENDING_USER = "pending_user"
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PLAN_CONTEXT_SSO = "is_sso"
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PLAN_CONTEXT_REDIRECT = "redirect"
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PLAN_CONTEXT_APPLICATION = "application"
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PLAN_CONTEXT_SOURCE = "source"
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# Is set by the Flow Planner when a FlowToken was used, and the currently active flow plan
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# was restored.
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PLAN_CONTEXT_IS_RESTORED = "is_restored"
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GAUGE_FLOWS_CACHED = UpdatingGauge(
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"authentik_flows_cached",
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"Cached flows",
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update_func=lambda: len(cache.keys("flow_*") or []),
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)
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HIST_FLOWS_PLAN_TIME = Histogram(
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"authentik_flows_plan_time",
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"Duration to build a plan for a flow",
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["flow_slug"],
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)
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CACHE_TIMEOUT = int(CONFIG.y("redis.cache_timeout_flows"))
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def cache_key(flow: Flow, user: Optional[User] = None) -> str:
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"""Generate Cache key for flow"""
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prefix = f"flow_{flow.pk}"
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if user:
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prefix += f"#{user.pk}"
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return prefix
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@dataclass
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class FlowPlan:
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"""This data-class is the output of a FlowPlanner. It holds a flat list
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of all Stages that should be run."""
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flow_pk: str
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bindings: list[FlowStageBinding] = field(default_factory=list)
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context: dict[str, Any] = field(default_factory=dict)
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markers: list[StageMarker] = field(default_factory=list)
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def append_stage(self, stage: Stage, marker: Optional[StageMarker] = None):
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"""Append `stage` to all stages, optionally with stage marker"""
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return self.append(FlowStageBinding(stage=stage), marker)
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def append(self, binding: FlowStageBinding, marker: Optional[StageMarker] = None):
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"""Append `stage` to all stages, optionally with stage marker"""
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self.bindings.append(binding)
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self.markers.append(marker or StageMarker())
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def insert_stage(self, stage: Stage, marker: Optional[StageMarker] = None):
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"""Insert stage into plan, as immediate next stage"""
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self.bindings.insert(1, FlowStageBinding(stage=stage, order=0))
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self.markers.insert(1, marker or StageMarker())
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def next(self, http_request: Optional[HttpRequest]) -> Optional[FlowStageBinding]:
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"""Return next pending stage from the bottom of the list"""
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if not self.has_stages:
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return None
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binding = self.bindings[0]
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marker = self.markers[0]
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if marker.__class__ is not StageMarker:
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LOGGER.debug("f(plan_inst): stage has marker", binding=binding, marker=marker)
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marked_stage = marker.process(self, binding, http_request)
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if not marked_stage:
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LOGGER.debug("f(plan_inst): marker returned none, next stage", binding=binding)
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self.bindings.remove(binding)
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self.markers.remove(marker)
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if not self.has_stages:
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return None
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# pylint: disable=not-callable
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return self.next(http_request)
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return marked_stage
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def pop(self):
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"""Pop next pending stage from bottom of list"""
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self.markers.pop(0)
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self.bindings.pop(0)
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@property
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def has_stages(self) -> bool:
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"""Check if there are any stages left in this plan"""
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return len(self.markers) + len(self.bindings) > 0
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class FlowPlanner:
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"""Execute all policies to plan out a flat list of all Stages
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that should be applied."""
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use_cache: bool
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allow_empty_flows: bool
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flow: Flow
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_logger: BoundLogger
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def __init__(self, flow: Flow):
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self.use_cache = True
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self.allow_empty_flows = False
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self.flow = flow
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self._logger = get_logger().bind(flow=flow)
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def plan(
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self, request: HttpRequest, default_context: Optional[dict[str, Any]] = None
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) -> FlowPlan:
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"""Check each of the flows' policies, check policies for each stage with PolicyBinding
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and return ordered list"""
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with Hub.current.start_span(
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op="authentik.flow.planner.plan", description=self.flow.slug
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) as span:
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span: Span
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span.set_data("flow", self.flow)
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span.set_data("request", request)
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self._logger.debug(
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"f(plan): starting planning process",
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)
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# Bit of a workaround here, if there is a pending user set in the default context
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# we use that user for our cache key
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# to make sure they don't get the generic response
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if default_context and PLAN_CONTEXT_PENDING_USER in default_context:
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user = default_context[PLAN_CONTEXT_PENDING_USER]
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else:
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user = request.user
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# First off, check the flow's direct policy bindings
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# to make sure the user even has access to the flow
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engine = PolicyEngine(self.flow, user, request)
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if default_context:
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span.set_data("default_context", cleanse_dict(default_context))
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engine.request.context = default_context
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engine.build()
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result = engine.result
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if not result.passing:
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raise FlowNonApplicableException(",".join(result.messages))
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# User is passing so far, check if we have a cached plan
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cached_plan_key = cache_key(self.flow, user)
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cached_plan = cache.get(cached_plan_key, None)
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if cached_plan and self.use_cache:
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self._logger.debug(
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"f(plan): taking plan from cache",
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key=cached_plan_key,
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)
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# Reset the context as this isn't factored into caching
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cached_plan.context = default_context or {}
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return cached_plan
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self._logger.debug(
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"f(plan): building plan",
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)
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plan = self._build_plan(user, request, default_context)
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cache.set(cache_key(self.flow, user), plan, CACHE_TIMEOUT)
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GAUGE_FLOWS_CACHED.update()
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if not plan.bindings and not self.allow_empty_flows:
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raise EmptyFlowException()
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return plan
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def _build_plan(
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self,
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user: User,
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request: HttpRequest,
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default_context: Optional[dict[str, Any]],
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) -> FlowPlan:
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"""Build flow plan by checking each stage in their respective
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order and checking the applied policies"""
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with Hub.current.start_span(
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op="authentik.flow.planner.build_plan",
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description=self.flow.slug,
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) as span, HIST_FLOWS_PLAN_TIME.labels(flow_slug=self.flow.slug).time():
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span: Span
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span.set_data("flow", self.flow)
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span.set_data("user", user)
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span.set_data("request", request)
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plan = FlowPlan(flow_pk=self.flow.pk.hex)
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if default_context:
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plan.context = default_context
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# Check Flow policies
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for binding in FlowStageBinding.objects.filter(target__pk=self.flow.pk).order_by(
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"order"
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):
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binding: FlowStageBinding
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stage = binding.stage
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marker = StageMarker()
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if binding.evaluate_on_plan:
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self._logger.debug(
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"f(plan): evaluating on plan",
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stage=binding.stage,
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)
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engine = PolicyEngine(binding, user, request)
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engine.request.context = plan.context
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engine.build()
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if engine.passing:
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self._logger.debug(
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"f(plan): stage passing",
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stage=binding.stage,
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)
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else:
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stage = None
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else:
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self._logger.debug(
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"f(plan): not evaluating on plan",
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stage=binding.stage,
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)
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if binding.re_evaluate_policies and stage:
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self._logger.debug(
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"f(plan): stage has re-evaluate marker",
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stage=binding.stage,
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)
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marker = ReevaluateMarker(binding=binding)
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if stage:
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plan.append(binding, marker)
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HIST_FLOWS_PLAN_TIME.labels(flow_slug=self.flow.slug)
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self._logger.debug(
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"f(plan): finished building",
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)
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return plan
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