Commit 4655b204 authored by WinterFairy's avatar WinterFairy
Browse files

Add the actual control port filter proxy

Written in python for simplicity and security.
The script is going to be run by the vidalia user,
which has access to the real Tor control port.
parent 0c752b5f
# Tor control port filter proxy, only white-listing SIGNAL NEWNYM.
# This filter proxy should allow Torbutton to request a
# new Tor circuit, without exposing dangerous control requests
# like "GETINFO address" to applications running as a local user.
# If something goes wrong, an error code is returned, and
# Torbutton will display a warning dialog that New Identity failed.
# Only one application can talk through this filter proxy
# simultaneously. A malicious application that is running as a
# local user could use this to prevent other applications from
# doing NEWNYM. But it could just as well rewrite the
# TOR_CONTROL_PORT environment varible to itself or do something else.
import socket
import binascii
class UnexpectedAnswer(Exception):
def __init__(self, msg):
self.msg = msg
def __str__(self):
return "[UnexpectedAnswer] " + self.msg
def do_newnym_real():
# Read authentication cookie
with open("/var/run/tor/control.authcookie", "rb") as f:
rawcookie =
hexcookie = binascii.hexlify(rawcookie)
# Connect to the real control port
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
readh = sock.makefile("r")
writeh = sock.makefile("w")
# Authenticate
writeh.write("AUTHENTICATE " + hexcookie + "\n")
answer = readh.readline(128)
if answer.find("250") != 0:
raise UnexpectedAnswer("AUTHENTICATE failed")
# Send the newnym signal
writeh.write("SIGNAL NEWNYM\n")
answer = readh.readline(128)
if answer.find("250") != 0:
raise UnexpectedAnswer("SIGNAL NEWNYM failed")
# Close the connection
answer = readh.readline(128)
if answer.find("250") != 0:
raise UnexpectedAnswer("QUIT failed")
def do_newnym():
# Catch innocent exceptions, will report error instead
print "Newnym went fine"
return True
except (IOError, UnexpectedAnswer) as e:
print "Warning: Couldn't perform newnym!"
print e
return False
def handle_connection(sock):
# Create file handles for the socket
readh = sock.makefile('r')
writeh = sock.makefile('w')
# Keep accepting commands
while True:
# Read in a newline terminated line (max 128 chars)
line = readh.readline(128)
if not line: break
# Check what it is
if line.find('AUTHENTICATE') == 0:
# Don't check authentication, since only
# safe commands are allowed
writeh.write('250 OK\n')
elif line.find('SIGNAL NEWNYM') == 0:
# Perform a real SIGNAL NEWNYM (new Tor circuit)
if do_newnym():
writeh.write('250 OK\n')
writeh.write('510 Newnym signal failed\n')
elif line.find('QUIT') == 0:
# Quit session
writeh.write('250 Closing connection\n')
# Everything else we ignore/block
writeh.write('510 Command filtered\n')
# Ensure the answer was written
# Ensure all data was written
def main():
# Listen on port 9052 (we cannot use 9051 as Tor uses that one)
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.bind(("", 9052))
print "Tor control port filter started, listening on 9052"
# Accept and handle connections one after one,
# sessions are short enough that the added complexity of
# simultaneous connections are unnecessary (in absence of attacks)
while True:
clisock, cliaddr = server.accept()
print "Accepted a connection"
print "Connection closed"
except IOError:
print "Connection closed (IOError)"
if __name__ == "__main__":
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