authentik/passbook/factors/view.py

"""passbook multi-factor authentication engine"""
from typing import List, Tuple

from django.contrib.auth import login
from django.contrib.auth.mixins import UserPassesTestMixin
from django.shortcuts import get_object_or_404, redirect, reverse
from django.utils.http import urlencode
from django.views.generic import View
from structlog import get_logger

from passbook.core.models import Factor, User
from passbook.core.views.utils import PermissionDeniedView
from passbook.lib.utils.reflection import class_to_path, path_to_class
from passbook.lib.utils.urls import is_url_absolute
from passbook.policies.engine import PolicyEngine

LOGGER = get_logger()

def _redirect_with_qs(view, get_query_set=None):
    """Wrapper to redirect whilst keeping GET Parameters"""
    target = reverse(view)
    if get_query_set:
        target += '?' + urlencode({key: value for key, value in get_query_set.items()})
    return redirect(target)


# Argument used to redirect user after login
NEXT_ARG_NAME = 'next'

class AuthenticationView(UserPassesTestMixin, View):
    """Wizard-like Multi-factor authenticator"""

    SESSION_FACTOR = 'passbook_factor'
    SESSION_PENDING_FACTORS = 'passbook_pending_factors'
    SESSION_PENDING_USER = 'passbook_pending_user'
    SESSION_USER_BACKEND = 'passbook_user_backend'
    SESSION_IS_SSO_LOGIN = 'passbook_sso_login'

    pending_user: User
    pending_factors: List[Tuple[str, str]] = []

    _current_factor_class: Factor

    current_factor: Factor

    # Allow only not authenticated users to login
    def test_func(self):
        return AuthenticationView.SESSION_PENDING_USER in self.request.session

    def handle_no_permission(self):
        # Function from UserPassesTestMixin
        if NEXT_ARG_NAME in self.request.GET:
            return redirect(self.request.GET.get(NEXT_ARG_NAME))
        if self.request.user.is_authenticated:
            return _redirect_with_qs('passbook_core:overview', self.request.GET)
        return _redirect_with_qs('passbook_core:auth-login', self.request.GET)

    def get_pending_factors(self):
        """Loading pending factors from Database or load from session variable"""
        # Write pending factors to session
        if AuthenticationView.SESSION_PENDING_FACTORS in self.request.session:
            return self.request.session[AuthenticationView.SESSION_PENDING_FACTORS]
        # Get an initial list of factors which are currently enabled
        # and apply to the current user. We check policies here and block the request
        _all_factors = Factor.objects.filter(enabled=True).order_by('order').select_subclasses()
        pending_factors = []
        for factor in _all_factors:
            LOGGER.debug("Checking if factor applies to user",
                         factor=factor, user=self.pending_user)
            policy_engine = PolicyEngine(factor.policies.all())
            policy_engine.for_user(self.pending_user).with_request(self.request).build()
            if policy_engine.passing:
                pending_factors.append((factor.uuid.hex, factor.type))
                LOGGER.debug("Factor applies", factor=factor, user=self.pending_user)
        return pending_factors

    def dispatch(self, request, *args, **kwargs):
        # Check if user passes test (i.e. SESSION_PENDING_USER is set)
        user_test_result = self.get_test_func()()
        if not user_test_result:
            return self.handle_no_permission()
        # Extract pending user from session (only remember uid)
        self.pending_user = get_object_or_404(
            User, id=self.request.session[AuthenticationView.SESSION_PENDING_USER])
        self.pending_factors = self.get_pending_factors()
        # Read and instantiate factor from session
        factor_uuid, factor_class = None, None
        if AuthenticationView.SESSION_FACTOR not in request.session:
            # Case when no factors apply to user, return error denied
            if not self.pending_factors:
                # Case when user logged in from SSO provider and no more factors apply
                if AuthenticationView.SESSION_IS_SSO_LOGIN in request.session:
                    LOGGER.debug("User authenticated with SSO, logging in...")
                    return self._user_passed()
                return self.user_invalid()
            factor_uuid, factor_class = self.pending_factors[0]
        else:
            factor_uuid, factor_class = request.session[AuthenticationView.SESSION_FACTOR]
        # Lookup current factor object
        self.current_factor = Factor.objects.filter(uuid=factor_uuid).select_subclasses().first()
        # Instantiate Next Factor and pass request
        factor = path_to_class(factor_class)
        self._current_factor_class = factor(self)
        self._current_factor_class.pending_user = self.pending_user
        self._current_factor_class.request = request
        return super().dispatch(request, *args, **kwargs)

    def get(self, request, *args, **kwargs):
        """pass get request to current factor"""
        LOGGER.debug("Passing GET", view_class=class_to_path(self._current_factor_class.__class__))
        return self._current_factor_class.get(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        """pass post request to current factor"""
        LOGGER.debug("Passing POST", view_class=class_to_path(self._current_factor_class.__class__))
        return self._current_factor_class.post(request, *args, **kwargs)

    def user_ok(self):
        """Redirect to next Factor"""
        LOGGER.debug("Factor passed",
                     factor_class=class_to_path(self._current_factor_class.__class__))
        # Remove passed factor from pending factors
        current_factor_tuple = (self.current_factor.uuid.hex,
                                class_to_path(self._current_factor_class.__class__))
        if current_factor_tuple in self.pending_factors:
            self.pending_factors.remove(current_factor_tuple)
        next_factor = None
        if self.pending_factors:
            next_factor = self.pending_factors.pop()
            # Save updated pening_factor list to session
            self.request.session[AuthenticationView.SESSION_PENDING_FACTORS] = \
                self.pending_factors
            self.request.session[AuthenticationView.SESSION_FACTOR] = next_factor
            LOGGER.debug("Rendering Factor", next_factor=next_factor)
            return _redirect_with_qs('passbook_core:auth-process', self.request.GET)
        # User passed all factors
        LOGGER.debug("User passed all factors, logging in")
        return self._user_passed()

    def user_invalid(self):
        """Show error message, user cannot login.
        This should only be shown if user authenticated successfully, but is disabled/locked/etc"""
        LOGGER.debug("User invalid")
        self.cleanup()
        return _redirect_with_qs('passbook_core:auth-denied', self.request.GET)

    def _user_passed(self):
        """User Successfully passed all factors"""
        backend = self.request.session[AuthenticationView.SESSION_USER_BACKEND]
        login(self.request, self.pending_user, backend=backend)
        LOGGER.debug("Logged in", user=self.pending_user)
        # Cleanup
        self.cleanup()
        next_param = self.request.GET.get(NEXT_ARG_NAME, None)
        if next_param and not is_url_absolute(next_param):
            return redirect(next_param)
        return _redirect_with_qs('passbook_core:overview')

    def cleanup(self):
        """Remove temporary data from session"""
        session_keys = [self.SESSION_FACTOR, self.SESSION_PENDING_FACTORS,
                        self.SESSION_PENDING_USER, self.SESSION_USER_BACKEND, ]
        for key in session_keys:
            if key in self.request.session:
                del self.request.session[key]
        LOGGER.debug("Cleaned up sessions")

class FactorPermissionDeniedView(PermissionDeniedView):
    """User could not be authenticated"""