diff options
Diffstat (limited to 'paramiko/transport.py')
| -rw-r--r-- | paramiko/transport.py | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/paramiko/transport.py b/paramiko/transport.py index 68519f90..a99e077d 100644 --- a/paramiko/transport.py +++ b/paramiko/transport.py @@ -50,7 +50,7 @@ from paramiko.common import ( MSG_CHANNEL_FAILURE, MSG_CHANNEL_DATA, MSG_CHANNEL_EXTENDED_DATA, MSG_CHANNEL_WINDOW_ADJUST, MSG_CHANNEL_REQUEST, MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MIN_WINDOW_SIZE, MIN_PACKET_SIZE, MAX_WINDOW_SIZE, - DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE, + DEFAULT_WINDOW_SIZE, DEFAULT_MAX_PACKET_SIZE, HIGHEST_USERAUTH_MESSAGE_ID, ) from paramiko.compress import ZlibCompressor, ZlibDecompressor from paramiko.dsskey import DSSKey @@ -1831,6 +1831,43 @@ class Transport(threading.Thread, ClosingContextManager): max_packet_size = self.default_max_packet_size return clamp_value(MIN_PACKET_SIZE, max_packet_size, MAX_WINDOW_SIZE) + def _ensure_authed(self, ptype, message): + """ + Checks message type against current auth state. + + If server mode, and auth has not succeeded, and the message is of a + post-auth type (channel open or global request) an appropriate error + response Message is crafted and returned to caller for sending. + + Otherwise (client mode, authed, or pre-auth message) returns None. + """ + if ( + not self.server_mode + or ptype <= HIGHEST_USERAUTH_MESSAGE_ID + or self.is_authenticated() + ): + return None + # WELP. We must be dealing with someone trying to do non-auth things + # without being authed. Tell them off, based on message class. + reply = Message() + # Global requests have no details, just failure. + if ptype == MSG_GLOBAL_REQUEST: + reply.add_byte(cMSG_REQUEST_FAILURE) + # Channel opens let us reject w/ a specific type + message. + elif ptype == MSG_CHANNEL_OPEN: + kind = message.get_text() + chanid = message.get_int() + reply.add_byte(cMSG_CHANNEL_OPEN_FAILURE) + reply.add_int(chanid) + reply.add_int(OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED) + reply.add_string('') + reply.add_string('en') + # NOTE: Post-open channel messages do not need checking; the above will + # reject attemps to open channels, meaning that even if a malicious + # user tries to send a MSG_CHANNEL_REQUEST, it will simply fall under + # the logic that handles unknown channel IDs (as the channel list will + # be empty.) + return reply def run(self): # (use the exposed "run" method, because if we specify a thread target @@ -1889,7 +1926,11 @@ class Transport(threading.Thread, ClosingContextManager): continue if ptype in self._handler_table: - self._handler_table[ptype](self, m) + error_msg = self._ensure_authed(ptype, m) + if error_msg: + self._send_message(error_msg) + else: + self._handler_table[ptype](self, m) elif ptype in self._channel_handler_table: chanid = m.get_int() chan = self._channels.get(chanid) |