api: make 401 messages clearer

closes #755

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/api/auth.py

@@ -4,6 +4,7 @@ from binascii import Error
 from typing import Any, Optional, Union
 
 from rest_framework.authentication import BaseAuthentication, get_authorization_header
+from rest_framework.exceptions import AuthenticationFailed
 from rest_framework.request import Request
 from structlog.stdlib import get_logger
 
@@ -14,7 +15,7 @@ LOGGER = get_logger()
 
 # pylint: disable=too-many-return-statements
 def token_from_header(raw_header: bytes) -> Optional[Token]:
-    """raw_header in the Format of `Basic dGVzdDp0ZXN0`"""
+    """raw_header in the Format of `Bearer dGVzdDp0ZXN0`"""
     auth_credentials = raw_header.decode()
     if auth_credentials == "":
         return None
@@ -25,28 +26,27 @@ def token_from_header(raw_header: bytes) -> Optional[Token]:
             auth_type, body = plain.split()
             auth_credentials = f"{auth_type} {b64encode(body.encode()).decode()}"
         except (UnicodeDecodeError, Error):
-            return None
+            raise AuthenticationFailed("Malformed header")
     auth_type, auth_credentials = auth_credentials.split()
     if auth_type.lower() not in ["basic", "bearer"]:
         LOGGER.debug("Unsupported authentication type, denying", type=auth_type.lower())
-        return None
+        raise AuthenticationFailed("Unsupported authentication type")
     password = auth_credentials
     if auth_type.lower() == "basic":
         try:
             auth_credentials = b64decode(auth_credentials.encode()).decode()
         except (UnicodeDecodeError, Error):
-            return None
+            raise AuthenticationFailed("Malformed header")
         # Accept credentials with username and without
         if ":" in auth_credentials:
             _, password = auth_credentials.split(":")
         else:
             password = auth_credentials
     if password == "":  # nosec
-        return None
+        raise AuthenticationFailed("Malformed header")
     tokens = Token.filter_not_expired(key=password, intent=TokenIntents.INTENT_API)
     if not tokens.exists():
-        LOGGER.debug("Token not found")
-        return None
+        raise AuthenticationFailed("Token invalid/expired")
     return tokens.first()
 
 
@@ -58,6 +58,7 @@ class AuthentikTokenAuthentication(BaseAuthentication):
         auth = get_authorization_header(request)
 
         token = token_from_header(auth)
+        # None is only returned when the header isn't set.
         if not token:
             return None
 

authentik/api/tests/test_auth.py

@@ -3,6 +3,7 @@ from base64 import b64encode
 
 from django.test import TestCase
 from guardian.shortcuts import get_anonymous_user
+from rest_framework.exceptions import AuthenticationFailed
 
 from authentik.api.auth import token_from_header
 from authentik.core.models import Token, TokenIntents
@@ -28,17 +29,21 @@ class TestAPIAuth(TestCase):
 
     def test_invalid_type(self):
         """Test invalid type"""
-        self.assertIsNone(token_from_header("foo bar".encode()))
+        with self.assertRaises(AuthenticationFailed):
+            token_from_header("foo bar".encode())
 
     def test_invalid_decode(self):
         """Test invalid bas64"""
-        self.assertIsNone(token_from_header("Basic bar".encode()))
+        with self.assertRaises(AuthenticationFailed):
+            token_from_header("Basic bar".encode())
 
     def test_invalid_empty_password(self):
         """Test invalid with empty password"""
-        self.assertIsNone(token_from_header("Basic :".encode()))
+        with self.assertRaises(AuthenticationFailed):
+            token_from_header("Basic :".encode())
 
     def test_invalid_no_token(self):
         """Test invalid with no token"""
-        auth = b64encode(":abc".encode()).decode()
-        self.assertIsNone(token_from_header(f"Basic :{auth}".encode()))
+        with self.assertRaises(AuthenticationFailed):
+            auth = b64encode(":abc".encode()).decode()
+            self.assertIsNone(token_from_header(f"Basic :{auth}".encode()))

authentik/core/channels.py

@@ -1,6 +1,7 @@
 """Channels base classes"""
 from channels.exceptions import DenyConnection
 from channels.generic.websocket import JsonWebsocketConsumer
+from rest_framework.exceptions import AuthenticationFailed
 from structlog.stdlib import get_logger
 
 from authentik.api.auth import token_from_header
@@ -22,9 +23,13 @@ class AuthJsonConsumer(JsonWebsocketConsumer):
 
         raw_header = headers[b"authorization"]
 
-        token = token_from_header(raw_header)
-        if not token:
-            LOGGER.warning("Failed to authenticate")
+        try:
+            token = token_from_header(raw_header)
+            # token is only None when no header was given, in which case we deny too
+            if not token:
+                raise DenyConnection()
+        except AuthenticationFailed as exc:
+            LOGGER.warning("Failed to authenticate", exc=exc)
             raise DenyConnection()
 
         self.user = token.user