#!/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 binascii 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 from cryptech.libhal import HAL_OK, RPC_FUNC_GET_VERSION, RPC_FUNC_LOGOUT, RPC_FUNC_LOGOUT_ALL logger = logging.getLogger("cryptech_muxd") SLIP_END = b"\300" # Indicates end of SLIP packet SLIP_ESC = b"\333" # Indicates byte stuffing SLIP_ESC_END = b"\334" # ESC ESC_END means END data byte SLIP_ESC_ESC = b"\335" # ESC ESC_ESC means ESC data byte Control_U = b"\025" # Console: clear line Control_M = b"\015" # 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:] logout_msg = struct.pack(">LL", RPC_FUNC_LOGOUT, 0) logout_all_msg = struct.pack(">LL", RPC_FUNC_LOGOUT_ALL, 0) class SerialIOStream(tornado.iostream.BaseIOStream): """ Implementation of a Tornado IOStream over a PySerial device. """ # In theory, we want zero (non-blocking mode) for both the read # and write timeouts here so that PySerial will let Tornado handle # all the select()/poll()/epoll()/kqueue() fun, delivering maximum # throughput to all. In practice, this has always worked for the # author, but another developer reports that on some (not all) # platforms this fails consistently with Tornado reporting write # timeout errors, presumably as the result of receiving an IOError # or OSError exception from PySerial. For reasons we don't really # understand, setting a PySerial write timeout on the order of # 50-100 ms "solves" this problem. Again in theory, this will # result in lower throughput if PySerial spends too much time # blocking on a single serial device when Tornado could be doing # something useful elsewhere, but such is life. def __init__(self, device): self.serial = serial.Serial(device, 921600, timeout = 0, write_timeout = 0.1) 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) if tornado.version > "5": # .. versionchanged:: 5.0 # Interface redesigned to take a buffer and return a number # of bytes instead of a freshly-allocated object. def read_from_fd(self, buf): buf[:] = self.serial.read(len(buf)) return len(buf) or None else: 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 = 0o600): 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 = 0, queue = None): "Send a query to the HSM." logger.debug("RPC send: %s", ":".join(binascii.hexlify(c) for c in query)) if queue is not None: 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.values(): q.put_nowait(None) return logger.debug("RPC recv: %s", ":".join(binascii.hexlify(c) for c in reply)) if reply == SLIP_END: continue try: handle = client_handle_get(slip_decode(reply)) except: logger.debug("RPC skipping bad packet") continue if handle not in self.queues: logger.debug("RPC ignoring response: handle 0x%x", handle) continue logger.debug("RPC queue put: handle 0x%x, qsize %s", handle, self.queues[handle].qsize()) self.queues[handle].put_nowait(reply) def logout_all(self): "Execute an RPC LOGOUT_ALL operation." return self.rpc_input(slip_encode(logout_all_msg)) 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 = self.next_client_handle() 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() query = slip_encode(client_handle_set(logout_msg, handle)) yield self.serial.rpc_input(query, handle) return client_handle = int(time.time()) << 4 @classmethod def next_client_handle(cls): cls.client_handle += 1 cls.client_handle &= 0xFFFFFFFF return cls.client_handle class CTYIOStream(SerialIOStream): """ Tornado IOStream for a serial console channel. """ def __init__(self, device, console_log = None): super(CTYIOStream, self).__init__(device) self.attached_cty = None self.console_log = console_log @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: futures = [] if self.console_log is not None: futures.append(self.console_log.write(buffer)) if self.attached_cty is not None: futures.append(self.attached_cty.write(buffer)) if futures: yield futures 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.items(): 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 = struct.pack(">LL", RPC_FUNC_GET_VERSION, 0) RPC_reply = struct.pack(">LLL", RPC_FUNC_GET_VERSION, 0, 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(binascii.hexlify(c) for c in response)) is_cty = any(prompt in response for prompt in (b"Username:", b"Password:", b"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("-L", "--console-log", type = argparse.FileType("a"), help = "log console output to file") 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("--rpc-socket-mode", help = "permission bits for RPC socket inode", default = 0o600, type = lambda s: int(s, 8)) 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")) parser.add_argument("--cty-socket-mode", help = "permission bits for CTY socket inode", default = 0o600, type = lambda s: int(s, 8)) 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) if args.console_log is not None: console_log = tornado.iostream.PipeIOStream(args.console_log.fileno()) else: console_log = None 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, args.rpc_socket_mode) futures.append(rpc_stream.rpc_output_loop()) futures.append(rpc_stream.logout_all()) if args.cty_device is None: logger.warn("No CTY device found") else: cty_stream = CTYIOStream(device = args.cty_device, console_log = console_log) cty_server = CTYServer(cty_stream, args.cty_socket, args.cty_socket_mode) 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 (SystemExit, KeyboardInterrupt): pass except: logger.exception("Unhandled exception") else: logger.debug("Main loop exited")