#!/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
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# - Redistributions of source code must retain the above copyright notice,
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# - Redistributions in binary form must reproduce the above copyright
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"""
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 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)
@tornado.gen.coroutine
def rpc_output_loop(self):
"Handle reply stream HSM -> network."
while True:
try:
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
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."
logger.info("rpc connected %r", stream)
handle = stream.socket.fileno()
queue = tornado.queues.Queue()
while True:
try:
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)
reply = yield queue.get()
if reply is None:
raise QueuedStreamClosedError()
yield stream.write(SLIP_END + reply)
except tornado.iostream.StreamClosedError:
logger.info("rpc closing %r", stream)
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 disconnecting 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)
@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
# We probably need to add timeout wrappers around these I/O calls. See:
# http://tornadokevinlee.readthedocs.io/en/latest/gen.html#tornado.gen.with_timeout
yield self.write(SLIP_END + Control_U + SLIP_END + RPC_query + SLIP_END + Control_U + Control_M)
response = yield self.read_bytes(self.read_chunk_size, partial = True)
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("-p", "--probe",
nargs = "*",
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.verbose:
logging.getLogger().setLevel(logging.DEBUG if args.verbose > 1 else logging.INFO)
if args.probe is not None and (args.rpc_device is None or args.cty_device is None):
probe_devs = (set(args.probe) or
set(str(port) for port, desc, hwid in serial.tools.list_ports_posix.comports()
if "VID:PID=0403:6014" in hwid))
probe_devs -= set((args.rpc_device, args.cty_device))
if probe_devs:
logging.debug("Probing candidate devices %s", " ".join(probe_devs))
probe_results = yield dict((dev, ProbeIOStream(dev).run_probe()) for dev in probe_devs)
for dev, res in probe_results.iteritems():
if res == "cty" and args.cty_device is None:
logger.info("Selecting %s as cty device", dev)
args.cty_device = dev
if res == "rpc" and args.rpc_device is None:
logger.info("Selecting %s as rpc device", dev)
args.rpc_device = dev
futures = []
rpc_stream = RPCIOStream(device = args.rpc_device)
rpc_server = RPCServer(rpc_stream, args.rpc_socket)
futures.append(rpc_stream.rpc_output_loop())
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. Worry about
# that when we get to automatic device probing.
yield futures
if __name__ == "__main__":
try:
tornado.ioloop.IOLoop.current().run_sync(main)
except KeyboardInterrupt:
pass
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