#!/usr/bin/env python # # Copyright (c) 2016-2017, NORDUnet A/S All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are # met: # - Redistributions of source code must retain the above copyright notice, # this list of conditions and the following disclaimer. # # - Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in the # documentation and/or other materials provided with the distribution. # # - Neither the name of the NORDUnet nor the names of its contributors may # be used to endorse or promote products derived from this software # without specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS # IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED # TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A # PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT # HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED # TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. """ Implementation of Cryptech RPC protocol multiplexer in Python. Unlike the original C implementation, this uses SLIP encapsulation over a SOCK_STREAM channel, because support for SOCK_SEQPACKET is not what we might wish. We outsource all the heavy lifting for serial and network I/O to the PySerial and Tornado libraries, respectively. """ import os import sys import time import struct import atexit import weakref import logging import argparse import logging.handlers import serial import serial.tools.list_ports_posix import tornado.tcpserver import tornado.iostream import tornado.netutil import tornado.ioloop import tornado.queues import tornado.locks import tornado.gen logger = logging.getLogger("cryptech_muxd") SLIP_END = chr(0300) # Indicates end of SLIP packet SLIP_ESC = chr(0333) # Indicates byte stuffing SLIP_ESC_END = chr(0334) # ESC ESC_END means END data byte SLIP_ESC_ESC = chr(0335) # ESC ESC_ESC means ESC data byte Control_U = chr(0025) # Console: clear line Control_M = chr(0015) # Console: end of line def slip_encode(buffer): "Encode a buffer using SLIP encapsulation." return SLIP_END + buffer.replace(SLIP_ESC, SLIP_ESC + SLIP_ESC_ESC).replace(SLIP_END, SLIP_ESC + SLIP_ESC_END) + SLIP_END def slip_decode(buffer): "Decode a SLIP-encapsulated buffer." return buffer.strip(SLIP_END).replace(SLIP_ESC + SLIP_ESC_END, SLIP_END).replace(SLIP_ESC + SLIP_ESC_ESC, SLIP_ESC) def client_handle_get(msg): "Extract client_handle field from a Cryptech RPC message." return struct.unpack(">L", msg[4:8])[0] def client_handle_set(msg, handle): "Replace client_handle field in a Cryptech RPC message." return msg[:4] + struct.pack(">L", handle) + msg[8:] class SerialIOStream(tornado.iostream.BaseIOStream): """ Implementation of a Tornado IOStream over a PySerial device. """ def __init__(self, device): self.serial = serial.Serial(device, 921600, timeout = 0, write_timeout = 0) self.serial_device = device super(SerialIOStream, self).__init__() def fileno(self): return self.serial.fileno() def close_fd(self): self.serial.close() def write_to_fd(self, data): return self.serial.write(data) def read_from_fd(self): return self.serial.read(self.read_chunk_size) or None class PFUnixServer(tornado.tcpserver.TCPServer): """ Variant on tornado.tcpserver.TCPServer, listening on a PF_UNIX (aka PF_LOCAL) socket instead of a TCP socket. """ def __init__(self, serial_stream, socket_filename, mode = 0600): super(PFUnixServer, self).__init__() self.serial = serial_stream self.socket_filename = socket_filename self.add_socket(tornado.netutil.bind_unix_socket(socket_filename, mode)) atexit.register(self.atexit_unlink) def atexit_unlink(self): try: os.unlink(self.socket_filename) except: pass class RPCIOStream(SerialIOStream): """ Tornado IOStream for a serial RPC channel. """ def __init__(self, device): super(RPCIOStream, self).__init__(device) self.queues = weakref.WeakValueDictionary() self.rpc_input_lock = tornado.locks.Lock() @tornado.gen.coroutine def rpc_input(self, query, handle, queue): "Send a query to the HSM." logger.debug("RPC send: %s", ":".join("{:02x}".format(ord(c)) for c in query)) self.queues[handle] = queue with (yield self.rpc_input_lock.acquire()): yield self.write(query) logger.debug("RPC sent") @tornado.gen.coroutine def rpc_output_loop(self): "Handle reply stream HSM -> network." while True: try: logger.debug("RPC UART read") reply = yield self.read_until(SLIP_END) except tornado.iostream.StreamClosedError: logger.info("RPC UART closed") for q in self.queues.itervalues(): q.put_nowait(None) return logger.debug("RPC recv: %s", ":".join("{:02x}".format(ord(c)) for c in reply)) try: handle = client_handle_get(slip_decode(reply)) except: continue logger.debug("RPC queue put: handle 0x%x, qsize %s, maxsize %s", handle, self.queues[handle].qsize(), self.queues[handle].maxsize) self.queues[handle].put_nowait(reply) class QueuedStreamClosedError(tornado.iostream.StreamClosedError): "Deferred StreamClosedError passed throught a Queue." class RPCServer(PFUnixServer): """ Serve multiplexed Cryptech RPC over a PF_UNIX socket. """ @tornado.gen.coroutine def handle_stream(self, stream, address): "Handle one network connection." handle = stream.socket.fileno() queue = tornado.queues.Queue() logger.info("RPC connected %r, handle 0x%x", stream, handle) while True: try: logger.debug("RPC socket read, handle 0x%x", handle) query = yield stream.read_until(SLIP_END) if len(query) < 9: continue query = slip_encode(client_handle_set(slip_decode(query), handle)) yield self.serial.rpc_input(query, handle, queue) logger.debug("RPC queue wait, handle 0x%x", handle) reply = yield queue.get() if reply is None: raise QueuedStreamClosedError() logger.debug("RPC socket write, handle 0x%x", handle) yield stream.write(SLIP_END + reply) except tornado.iostream.StreamClosedError: logger.info("RPC closing %r, handle 0x%x", stream, handle) stream.close() return class CTYIOStream(SerialIOStream): """ Tornado IOStream for a serial console channel. """ def __init__(self, device): super(CTYIOStream, self).__init__(device) self.attached_cty = None @tornado.gen.coroutine def cty_output_loop(self): while True: try: buffer = yield self.read_bytes(self.read_chunk_size, partial = True) except tornado.iostream.StreamClosedError: logger.info("CTY UART closed") if self.attached_cty is not None: self.attached_cty.close() return try: if self.attached_cty is not None: yield self.attached_cty.write(buffer) except tornado.iostream.StreamClosedError: pass class CTYServer(PFUnixServer): """ Serve Cryptech console over a PF_UNIX socket. """ @tornado.gen.coroutine def handle_stream(self, stream, address): "Handle one network connection." if self.serial.attached_cty is not None: yield stream.write("[Console already in use, sorry]\n") stream.close() return logger.info("CTY connected to %r", stream) try: self.serial.attached_cty = stream while self.serial.attached_cty is stream: yield self.serial.write((yield stream.read_bytes(1024, partial = True))) except tornado.iostream.StreamClosedError: stream.close() finally: logger.info("CTY disconnected from %r", stream) if self.serial.attached_cty is stream: self.serial.attached_cty = None class ProbeIOStream(SerialIOStream): """ Tornado IOStream for probing a serial port. This is nasty. """ def __init__(self, device): super(ProbeIOStream, self).__init__(device) @classmethod @tornado.gen.coroutine def run_probes(cls, args): if args.rpc_device is not None and args.cty_device is not None: return if args.probe: devs = set(args.probe) else: devs = set(str(port) for port, desc, hwid in serial.tools.list_ports_posix.comports() if "VID:PID=0403:6014" in hwid) devs.discard(args.rpc_device) devs.discard(args.cty_device) if not devs: return logging.debug("Probing candidate devices %s", " ".join(devs)) results = yield dict((dev, ProbeIOStream(dev).run_probe()) for dev in devs) for dev, result in results.iteritems(): if result == "cty" and args.cty_device is None: logger.info("Selecting %s as CTY device", dev) args.cty_device = dev if result == "rpc" and args.rpc_device is None: logger.info("Selecting %s as RPC device", dev) args.rpc_device = dev @tornado.gen.coroutine def run_probe(self): RPC_query = chr(0) * 8 # client_handle = 0, function code = RPC_FUNC_GET_VERSION RPC_reply = chr(0) * 12 # opcode = RPC_FUNC_GET_VERSION, client_handle = 0, valret = HAL_OK probe_string = SLIP_END + Control_U + SLIP_END + RPC_query + SLIP_END + Control_U + Control_M yield self.write(probe_string) yield tornado.gen.sleep(0.5) response = yield self.read_bytes(self.read_chunk_size, partial = True) logger.debug("Probing %s: %r %s", self.serial_device, response, ":".join("{:02x}".format(ord(c)) for c in response)) is_cty = any(prompt in response for prompt in ("Username:", "Password:", "cryptech>")) try: is_rpc = response[response.index(SLIP_END + RPC_reply) + len(SLIP_END + RPC_reply) + 4] == SLIP_END except ValueError: is_rpc = False except IndexError: is_rpc = False assert not is_cty or not is_rpc result = None if is_cty: result = "cty" yield self.write(Control_U) if is_rpc: result = "rpc" yield self.write(SLIP_END) self.close() raise tornado.gen.Return(result) @tornado.gen.coroutine def main(): parser = argparse.ArgumentParser(formatter_class = argparse.ArgumentDefaultsHelpFormatter) parser.add_argument("-v", "--verbose", action = "count", help = "blather about what we're doing") parser.add_argument("-l", "--log-file", help = "log to file instead of stderr") parser.add_argument("-p", "--probe", nargs = "*", metavar = "DEVICE", help = "probe for device UARTs") parser.add_argument("--rpc-device", help = "RPC serial device name", default = os.getenv("CRYPTECH_RPC_CLIENT_SERIAL_DEVICE")) parser.add_argument("--rpc-socket", help = "RPC PF_UNIX socket name", default = os.getenv("CRYPTECH_RPC_CLIENT_SOCKET_NAME", "/tmp/.cryptech_muxd.rpc")) parser.add_argument("--cty-device", help = "CTY serial device name", default = os.getenv("CRYPTECH_CTY_CLIENT_SERIAL_DEVICE")) parser.add_argument("--cty-socket", help = "CTY PF_UNIX socket name", default = os.getenv("CRYPTECH_CTY_CLIENT_SOCKET_NAME", "/tmp/.cryptech_muxd.cty")) args = parser.parse_args() if args.log_file is not None: logging.getLogger().handlers[:] = [logging.handlers.WatchedFileHandler(args.log_file)] logging.getLogger().handlers[0].setFormatter( logging.Formatter("%(asctime)-15s %(name)s[%(process)d]:%(levelname)s: %(message)s", "%Y-%m-%d %H:%M:%S")) if args.verbose: logging.getLogger().setLevel(logging.DEBUG if args.verbose > 1 else logging.INFO) if args.probe is not None: yield ProbeIOStream.run_probes(args) futures = [] if args.rpc_device is None: logger.warn("No RPC device found") else: rpc_stream = RPCIOStream(device = args.rpc_device) rpc_server = RPCServer(rpc_stream, args.rpc_socket) futures.append(rpc_stream.rpc_output_loop()) if args.cty_device is None: logger.warn("No CTY device found") else: cty_stream = CTYIOStream(device = args.cty_device) cty_server = CTYServer(cty_stream, args.cty_socket) futures.append(cty_stream.cty_output_loop()) # Might want to use WaitIterator(dict(...)) here so we can # diagnose and restart output loops if they fail? if futures: yield futures if __name__ == "__main__": try: tornado.ioloop.IOLoop.current().run_sync(main) except KeyboardInterrupt: pass