"""passbook SAML IDP Views""" from django.contrib.auth import logout from django.contrib.auth.mixins import AccessMixin from django.core.exceptions import ValidationError from django.core.validators import URLValidator from django.http import HttpResponse, HttpResponseBadRequest from django.shortcuts import get_object_or_404, redirect, render, reverse from django.utils.datastructures import MultiValueDictKeyError from django.utils.decorators import method_decorator from django.utils.translation import gettext as _ from django.views import View from django.views.decorators.csrf import csrf_exempt from signxml.util import strip_pem_header from structlog import get_logger from passbook.audit.models import Event from passbook.core.models import Application from passbook.lib.mixins import CSRFExemptMixin from passbook.lib.utils.template import render_to_string from passbook.policies.engine import PolicyEngine from passbook.providers.saml import exceptions from passbook.providers.saml.models import SAMLProvider LOGGER = get_logger() URL_VALIDATOR = URLValidator(schemes=('http', 'https')) def _generate_response(request, provider: SAMLProvider): """Generate a SAML response using processor_instance and return it in the proper Django response.""" try: provider.processor.init_deep_link(request, '') ctx = provider.processor.generate_response() ctx['remote'] = provider ctx['is_login'] = True except exceptions.UserNotAuthorized: return render(request, 'saml/idp/invalid_user.html') return render(request, 'saml/idp/login.html', ctx) def render_xml(request, template, ctx): """Render template with content_type application/xml""" return render(request, template, context=ctx, content_type="application/xml") class AccessRequiredView(AccessMixin, View): """Mixin class for Views using a provider instance""" _provider = None @property def provider(self): """Get provider instance""" if not self._provider: application = get_object_or_404(Application, slug=self.kwargs['application']) self._provider = get_object_or_404(SAMLProvider, pk=application.provider_id) return self._provider def _has_access(self): """Check if user has access to application""" policy_engine = PolicyEngine(self.provider.application.policies.all(), self.request.user, self.request) policy_engine.build() return policy_engine.passing def dispatch(self, request, *args, **kwargs): if not request.user.is_authenticated: return self.handle_no_permission() if not self._has_access(): return render(request, 'login/denied.html', { 'title': _("You don't have access to this application"), 'is_login': True }) return super().dispatch(request, *args, **kwargs) class LoginBeginView(AccessRequiredView): """Receives a SAML 2.0 AuthnRequest from a Service Provider and stores it in the session prior to enforcing login.""" @method_decorator(csrf_exempt) def dispatch(self, request, application): if request.method == 'POST': source = request.POST else: source = request.GET # Store these values now, because Django's login cycle won't preserve them. try: request.session['SAMLRequest'] = source['SAMLRequest'] except (KeyError, MultiValueDictKeyError): return HttpResponseBadRequest('the SAML request payload is missing') request.session['RelayState'] = source.get('RelayState', '') return redirect(reverse('passbook_providers_saml:saml-login-process', kwargs={ 'application': application })) class RedirectToSPView(AccessRequiredView): """Return autosubmit form""" def get(self, request, acs_url, saml_response, relay_state): """Return autosubmit form""" return render(request, 'core/autosubmit_form.html', { 'url': acs_url, 'attrs': { 'SAMLResponse': saml_response, 'RelayState': relay_state } }) class LoginProcessView(AccessRequiredView): """Processor-based login continuation. Presents a SAML 2.0 Assertion for POSTing back to the Service Provider.""" def get(self, request, application): """Handle get request, i.e. render form""" LOGGER.debug("Request: %s", request) # Check if user has access if self.provider.application.skip_authorization: ctx = self.provider.processor.generate_response() # Log Application Authorization Event.create( action=Event.ACTION_AUTHORIZE_APPLICATION, request=request, app=self.provider.application.name, skipped_authorization=True) return RedirectToSPView.as_view()( request=request, acs_url=ctx['acs_url'], saml_response=ctx['saml_response'], relay_state=ctx['relay_state']) try: full_res = _generate_response(request, self.provider) return full_res except exceptions.CannotHandleAssertion as exc: LOGGER.debug(exc) def post(self, request, application): """Handle post request, return back to ACS""" LOGGER.debug("Request: %s", request) # Check if user has access if request.POST.get('ACSUrl', None): # User accepted request Event.create( action=Event.ACTION_AUTHORIZE_APPLICATION, request=request, app=self.provider.application.name, skipped_authorization=False) return RedirectToSPView.as_view()( request=request, acs_url=request.POST.get('ACSUrl'), saml_response=request.POST.get('SAMLResponse'), relay_state=request.POST.get('RelayState')) try: full_res = _generate_response(request, self.provider) return full_res except exceptions.CannotHandleAssertion as exc: LOGGER.debug(exc) class LogoutView(CSRFExemptMixin, AccessRequiredView): """Allows a non-SAML 2.0 URL to log out the user and returns a standard logged-out page. (SalesForce and others use this method, though it's technically not SAML 2.0).""" def get(self, request, application): """Perform logout""" logout(request) redirect_url = request.GET.get('redirect_to', '') try: URL_VALIDATOR(redirect_url) except ValidationError: pass else: return redirect(redirect_url) return render(request, 'saml/idp/logged_out.html') class SLOLogout(CSRFExemptMixin, AccessRequiredView): """Receives a SAML 2.0 LogoutRequest from a Service Provider, logs out the user and returns a standard logged-out page.""" def post(self, request, application): """Perform logout""" request.session['SAMLRequest'] = request.POST['SAMLRequest'] # TODO: Parse SAML LogoutRequest from POST data, similar to login_process(). # TODO: Modify the base processor to handle logouts? # TODO: Combine this with login_process(), since they are so very similar? # TODO: Format a LogoutResponse and return it to the browser. # XXX: For now, simply log out without validating the request. logout(request) return render(request, 'saml/idp/logged_out.html') class DescriptorDownloadView(AccessRequiredView): """Replies with the XML Metadata IDSSODescriptor.""" def get(self, request, application): """Replies with the XML Metadata IDSSODescriptor.""" entity_id = self.provider.issuer slo_url = request.build_absolute_uri(reverse('passbook_providers_saml:saml-logout', kwargs={ 'application': application })) sso_url = request.build_absolute_uri(reverse('passbook_providers_saml:saml-login', kwargs={ 'application': application })) pubkey = strip_pem_header(self.provider.signing_cert.replace('\r', '')).replace('\n', '') ctx = { 'entity_id': entity_id, 'cert_public_key': pubkey, 'slo_url': slo_url, 'sso_url': sso_url } metadata = render_to_string('saml/xml/metadata.xml', ctx) response = HttpResponse(metadata, content_type='application/xml') response['Content-Disposition'] = ('attachment; filename="' '%s_passbook_meta.xml"' % self.provider.name) return response class InitiateLoginView(AccessRequiredView): """IdP-initiated Login""" def get(self, request, application): """Initiates an IdP-initiated link to a simple SP resource/target URL.""" self.provider.processor.init_deep_link(request, '') self.provider.processor.is_idp_initiated = True return _generate_response(request, self.provider)