Initial tests proving CVE-2018-7750 / #1175

tests/test_transport.py

@@ -32,7 +32,7 @@
 import unittest
 
 from paramiko import Transport, SecurityOptions, ServerInterface, RSAKey, DSSKey, \
-    SSHException, ChannelException, Packetizer
+    SSHException, ChannelException, Packetizer, Channel
 from paramiko import AUTH_FAILED, AUTH_SUCCESSFUL
 from paramiko import OPEN_SUCCEEDED, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 from paramiko.common import MSG_KEXINIT, cMSG_CHANNEL_WINDOW_ADJUST, \
@@ -88,7 +88,11 @@ def check_channel_shell_request(self, channel):
 
     def check_global_request(self, kind, msg):
         self._global_request = kind
-        return False
+        # NOTE: for w/e reason, older impl of this returned False always, even
+        # tho that's only supposed to occur if the request cannot be served.
+        # For now, leaving that the default unless test supplies specific
+        # 'acceptable' request kind
+        return kind == 'acceptable'
 
     def check_channel_x11_request(self, channel, single_connection, auth_protocol, auth_cookie, screen_number):
         self._x11_single_connection = single_connection
@@ -922,3 +926,37 @@ def test_channel_send_memoryview(self):
             # sendall() accepts a memoryview instance
             chan.sendall(memoryview(data))
             self.assertEqual(sfile.read(len(data)), data)
+
+    def test_server_rejects_open_channel_without_auth(self):
+        try:
+            self.setup_test_server(connect_kwargs={})
+            self.tc.open_session()
+        except ChannelException as e:
+            assert e.code == OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
+        else:
+            assert False, "Did not raise ChannelException!"
+
+    def test_server_rejects_arbitrary_global_request_without_auth(self):
+        self.setup_test_server(connect_kwargs={})
+        # NOTE: this dummy global request kind would normally pass muster
+        # from the test server.
+        self.tc.global_request('acceptable')
+        # Global requests never raise exceptions, even on failure (not sure why
+        # this was the original design...ugh.) Best we can do to tell failure
+        # happened is that the client transport's global_response was set back
+        # to None; if it had succeeded, it would be the response Message.
+        err = "Unauthed global response incorrectly succeeded!"
+        assert self.tc.global_response is None, err
+
+    def test_server_rejects_port_forward_without_auth(self):
+        # NOTE: at protocol level port forward requests are treated same as a
+        # regular global request, but Paramiko server implements a special-case
+        # method for it, so it gets its own test. (plus, THAT actually raises
+        # an exception on the client side, unlike the general case...)
+        self.setup_test_server(connect_kwargs={})
+        try:
+            self.tc.request_port_forward('localhost', 1234)
+        except SSHException as e:
+            assert "forwarding request denied" in str(e)
+        else:
+            assert False, "Did not raise SSHException!"