rewrite PasswordFactor to use backends setting instead of trying all backends

passbook/core/auth/factors/password.py

@@ -1,8 +1,10 @@
 """passbook multi-factor authentication engine"""
+from inspect import Signature
 from logging import getLogger
 
 from django.contrib import messages
-from django.contrib.auth import authenticate
+from django.contrib.auth import _clean_credentials
+from django.contrib.auth.signals import user_login_failed
 from django.core.exceptions import PermissionDenied
 from django.forms.utils import ErrorList
 from django.shortcuts import redirect, reverse
@@ -15,10 +17,40 @@ from passbook.core.forms.authentication import PasswordFactorForm
 from passbook.core.models import Nonce
 from passbook.core.tasks import send_email
 from passbook.lib.config import CONFIG
+from passbook.lib.utils.reflection import path_to_class
 
 LOGGER = getLogger(__name__)
 
 
+def authenticate(request, backends, **credentials):
+    """If the given credentials are valid, return a User object.
+    Customized version of django's authenticate, which accepts a list of backends"""
+    for backend_path in backends:
+        backend = path_to_class(backend_path)()
+        try:
+            signature = Signature.from_callable(backend.authenticate)
+            signature.bind(request, **credentials)
+        except TypeError:
+            LOGGER.debug("Backend %s doesn't accept our arguments", backend)
+            # This backend doesn't accept these credentials as arguments. Try the next one.
+            continue
+        LOGGER.debug('Attempting authentication with %s...', backend)
+        try:
+            user = backend.authenticate(request, **credentials)
+        except PermissionDenied:
+            LOGGER.debug('Backend %r threw PermissionDenied', backend)
+            # This backend says to stop in our tracks - this user should not be allowed in at all.
+            break
+        if user is None:
+            continue
+        # Annotate the user object with the path of the backend.
+        user.backend = backend_path
+        return user
+
+    # The credentials supplied are invalid to all backends, fire signal
+    user_login_failed.send(sender=__name__, credentials=_clean_credentials(
+        credentials), request=request)
+
 class PasswordFactor(FormView, AuthenticationFactor):
     """Authentication factor which authenticates against django's AuthBackend"""
 
@@ -57,7 +89,7 @@ class PasswordFactor(FormView, AuthenticationFactor):
         for uid_field in uid_fields:
             kwargs[uid_field] = getattr(self.authenticator.pending_user, uid_field)
         try:
-            user = authenticate(self.request, **kwargs)
+            user = authenticate(self.request, self.authenticator.current_factor.backends, **kwargs)
             if user:
                 # User instance returned from authenticate() has .backend property set
                 self.authenticator.pending_user = user

passbook/core/forms/factors.py

@@ -1,13 +1,20 @@
 """passbook administration forms"""
 from django import forms
+from django.conf import settings
 from django.contrib.admin.widgets import FilteredSelectMultiple
 from django.utils.translation import gettext as _
 
 from passbook.core.models import DummyFactor, PasswordFactor
-from passbook.lib.fields import DynamicArrayField
+from passbook.lib.utils.reflection import path_to_class
 
 GENERAL_FIELDS = ['name', 'slug', 'order', 'policies', 'enabled']
 
+def get_authentication_backends():
+    """Return all available authentication backends as tuple set"""
+    for backend in settings.AUTHENTICATION_BACKENDS:
+        klass = path_to_class(backend)
+        yield backend, getattr(klass(), 'name', '%s (%s)' % (klass.__name__, klass.__module__))
+
 class PasswordFactorForm(forms.ModelForm):
     """Form to create/edit Password Factors"""
 
@@ -18,10 +25,9 @@ class PasswordFactorForm(forms.ModelForm):
         widgets = {
             'name': forms.TextInput(),
             'order': forms.NumberInput(),
-            'policies': FilteredSelectMultiple(_('policies'), False)
-        }
-        field_classes = {
-            'backends': DynamicArrayField
+            'policies': FilteredSelectMultiple(_('policies'), False),
+            'backends': FilteredSelectMultiple(_('backends'), False,
+                                               choices=get_authentication_backends())
         }
 
 class DummyFactorForm(forms.ModelForm):

passbook/core/migrations/0014_auto_20190226_0850.py

@@ -11,7 +11,7 @@ def create_initial_factor(apps, schema_editor):
             name='password',
             slug='password',
             order=0,
-            backends=[]
+            backends=['django.contrib.auth.backends.ModelBackend']
         )
 
 class Migration(migrations.Migration):

passbook/core/settings.py

@@ -47,8 +47,7 @@ SESSION_COOKIE_NAME = 'passbook_session'
 LANGUAGE_COOKIE_NAME = 'passbook_language'
 
 AUTHENTICATION_BACKENDS = [
-    'django.contrib.auth.backends.ModelBackend',
-    'passbook.oauth_client.backends.AuthorizedServiceBackend'
+    'django.contrib.auth.backends.ModelBackend'
 ]
 
 # Application definition

passbook/core/tests/test_auth_view.py

@@ -18,9 +18,12 @@ class TestFactorAuthentication(TestCase):
         super().setUp()
         self.password = ''.join(SystemRandom().choice(
             string.ascii_uppercase + string.digits) for _ in range(8))
-        self.factor, _ = PasswordFactor.objects.get_or_create(name='password',
-                                                              slug='password',
-                                                              backends=[])
+        self.factor, _ = PasswordFactor.objects.get_or_create(slug='password', defaults={
+            'name': 'password',
+            'slug': 'password',
+            'order': 0,
+            'backends': ['django.contrib.auth.backends.ModelBackend']
+        })
         self.user = User.objects.create_user(username='test',
                                              email='test@test.test',
                                              password=self.password)