Merge pull request #1828 from rkdarst/authenthicator_blacklist

Authenthicator blacklist

jupyterhub/auth.py

@@ -88,6 +88,20 @@ class Authenticator(LoggingConfigurable):
         """
     ).tag(config=True)
 
+    blacklist = Set(
+        help="""
+        Blacklist of usernames that are not allowed to log in.
+
+        Use this with supported authenticators to restrict which users can not log in. This is an
+        additional blacklist that further restricts users, beyond whatever restrictions the
+        authenticator has in place.
+
+        If empty, does not perform any additional restriction.
+
+        .. versionadded: 0.9
+        """
+    ).tag(config=True)
+
     @observe('whitelist')
     def _check_whitelist(self, change):
         short_names = [name for name in change['new'] if len(name) <= 1]
@@ -205,6 +219,21 @@ class Authenticator(LoggingConfigurable):
             return True
         return username in self.whitelist
 
+    def check_blacklist(self, username):
+        """Check if a username is blocked to authenticate based on blacklist configuration
+
+        Return True if username is allowed, False otherwise.
+        No blacklist means any username is allowed.
+
+        Names are normalized *before* being checked against the blacklist.
+
+        .. versionadded: 0.9
+        """
+        if not self.blacklist:
+            # No blacklist means any name is allowed
+            return True
+        return username not in self.blacklist
+
     async def get_authenticated_user(self, handler, data):
         """Authenticate the user who is attempting to log in
 
@@ -244,7 +273,14 @@ class Authenticator(LoggingConfigurable):
             self.log.warning("Disallowing invalid username %r.", username)
             return
 
+        blacklist_pass = await maybe_future(self.check_blacklist(username))
         whitelist_pass = await maybe_future(self.check_whitelist(username))
+        if blacklist_pass:
+            pass
+        else:
+            self.log.warning("User %r in blacklist. Stop authentication", username)
+            return
+
         if whitelist_pass:
             return authenticated
         else:

jupyterhub/tests/test_auth.py

@@ -103,6 +103,65 @@ def test_pam_auth_group_whitelist():
     assert authorized is None
 
 
+@pytest.mark.gen_test
+def test_pam_auth_blacklist():
+    # Null case compared to next case
+    authenticator = MockPAMAuthenticator()
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'wash',
+        'password': 'wash',
+    })
+    assert authorized['name'] == 'wash'
+
+    # Blacklist basics
+    authenticator = MockPAMAuthenticator(blacklist={'wash'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'wash',
+        'password': 'wash',
+    })
+    assert authorized is  None
+
+    # User in both white and blacklists: default deny.  Make error someday?
+    authenticator = MockPAMAuthenticator(blacklist={'wash'}, whitelist={'wash', 'kaylee'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'wash',
+        'password': 'wash',
+    })
+    assert authorized is None
+
+    # User not in blacklist can log in
+    authenticator = MockPAMAuthenticator(blacklist={'wash'}, whitelist={'wash', 'kaylee'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'kaylee',
+        'password': 'kaylee',
+    })
+    assert authorized['name'] == 'kaylee'
+
+    # User in whitelist, blacklist irrelevent
+    authenticator = MockPAMAuthenticator(blacklist={'mal'}, whitelist={'wash', 'kaylee'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'wash',
+        'password': 'wash',
+    })
+    assert authorized['name'] == 'wash'
+
+    # User in neither list
+    authenticator = MockPAMAuthenticator(blacklist={'mal'}, whitelist={'wash', 'kaylee'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'simon',
+        'password': 'simon',
+    })
+    assert authorized is None
+
+    # blacklist == {}
+    authenticator = MockPAMAuthenticator(blacklist=set(), whitelist={'wash', 'kaylee'})
+    authorized = yield authenticator.get_authenticated_user(None, {
+        'username': 'kaylee',
+        'password': 'kaylee',
+    })
+    assert authorized['name'] == 'kaylee'
+
+
 @pytest.mark.gen_test
 def test_pam_auth_no_such_group():
     authenticator = MockPAMAuthenticator(group_whitelist={'nosuchcrazygroup'})