Hardware authentication for Linux using ordinary USB Flash Drives.
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#!/usr/bin/env python
#
# Copyright (c) 2003-2007 Andrea Luzzardi <scox@sig11.org>
#
# This file is part of the pam_usb project. pam_usb is free software;
# you can redistribute it and/or modify it under the terms of the GNU General
# Public License version 2, as published by the Free Software Foundation.
#
# pam_usb is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 59 Temple
# Place, Suite 330, Boston, MA 02111-1307 USA
import os
import sys
import pwd
import getopt
import syslog
import gobject
import dbus
if getattr(dbus, 'version', (0,0,0)) >= (0,41,0):
import dbus.glib
try:
# Python 2.5
import xml.etree.ElementTree as et
except ImportError:
# Python 2.4
try:
import cElementTree as et
except ImportError:
import elementtree.ElementTree as et
class HotPlugDevice:
def __init__(self, serial):
self.__udi = None
self.__serial = serial
self.__callbacks = []
self.__bus = dbus.SystemBus()
self.__running = False
def run(self):
self.__scanDevices()
self.__registerSignals()
self.__running = True
gobject.MainLoop().run()
print 'signals registered'
def addCallback(self, callback):
self.__callbacks.append(callback)
def __scanDevices(self):
halService = self.__bus.get_object('org.freedesktop.Hal',
'/org/freedesktop/Hal/Manager')
halManager = dbus.Interface(halService, 'org.freedesktop.Hal.Manager')
for udi in halManager.FindDeviceStringMatch('info.bus', 'usb_device'):
self.__deviceAdded(udi)
def __registerSignals(self):
for signal, callback in (('DeviceAdded', self.__deviceAdded),
('DeviceRemoved', self.__deviceRemoved)):
self.__bus.add_signal_receiver(callback,
signal,
'org.freedesktop.Hal.Manager',
'org.freedesktop.Hal',
'/org/freedesktop/Hal/Manager')
def __deviceAdded(self, udi):
if self.__udi is not None:
return
deviceObj = self.__bus.get_object('org.freedesktop.Hal',
udi)
deviceProperties = deviceObj.GetAllProperties(
dbus_interface = 'org.freedesktop.Hal.Device')
if not deviceProperties.has_key('usb_device.serial'):
return
if deviceProperties['usb_device.serial'] != self.__serial:
return
self.__udi = udi
if self.__running:
[ cb('added') for cb in self.__callbacks ]
def __deviceRemoved(self, udi):
if self.__udi is None:
return
if self.__udi != udi:
return
self.__udi = None
if self.__running:
[ cb('removed') for cb in self.__callbacks ]
class Log:
def __init__(self):
syslog.openlog('pamusb-agent', syslog.LOG_PID | syslog.LOG_PERROR,
syslog.LOG_AUTH)
def info(self, message):
self.__logMessage(syslog.LOG_NOTICE, message)
def error(self, message):
self.__logMessage(syslog.LOG_ERR, message)
def __logMessage(self, priority, message):
syslog.syslog(priority, message)
def usage():
print 'Usage: %s [--help] [--config=path] [--daemon] [--check=path]' % \
os.path.basename(__file__)
sys.exit(1)
import getopt
try:
opts, args = getopt.getopt(sys.argv[1:], "hc:dc:",
["help", "config=", "daemon", "check="])
except getopt.GetoptError:
usage()
options = {'configFile' : '/etc/pamusb.conf',
'daemon' : False,
'check' : '/usr/bin/pamusb-check'}
if len(args) != 0:
usage()
for o, a in opts:
if o in ('-h', '--help'):
usage()
if o in ('-c', '--config'):
options['configFile'] = a
if o in ('-d', '--daemon'):
options['daemon'] = True
if o in ('-c', '--check'):
options['check'] = a
if not os.path.exists(options['check']):
print '%s not found.' % options['check']
print "You might specify manually pamusb-check's location using --check."
usage()
username = pwd.getpwuid(os.getuid())[0]
logger = Log()
doc = et.parse(options['configFile'])
users = doc.findall('users/user')
for user in users:
if user.get('id') == username:
break
else:
logger.error('User %s not found in configuration file' % username)
sys.exit(1)
events = {
'lock' : [],
'unlock' : []
}
for hotplug in user.findall('agent'):
events[hotplug.get('event')].append(hotplug.text)
deviceName = user.find('device').text.strip()
devices = doc.findall("devices/device")
for device in devices:
if device.get('id') == deviceName:
break
else:
logger.error('Device %s not found in configurtion file' % deviceName)
sys.exit(1)
serial = device.find('serial').text.strip()
def authChangeCallback(event):
if event == 'removed':
logger.info('Device "%s" has been removed, ' \
'locking down user "%s"...' % (deviceName, username))
for cmd in events['lock']:
logger.info('Running "%s"' % cmd)
os.system(cmd)
logger.info('Locked.')
return
logger.info('Device "%s" has been inserted. ' \
'Performing verification...' % deviceName)
cmdLine = "%s --quiet --config=%s --service=pamusb-agent %s" % (
options['check'], options['configFile'], username)
logger.info('Executing "%s"' % cmdLine)
if not os.system(cmdLine):
logger.info('Authentication succeeded. ' \
'Unlocking user "%s"...' % username)
for cmd in events['unlock']:
logger.info('Running "%s"' % cmd)
os.system(cmd)
logger.info('Unlocked.')
else:
logger.info('Authentication failed for device %s. ' \
'Keeping user "%s" locked down.' % (deviceName, username))
hpDev = HotPlugDevice(serial)
hpDev.addCallback(authChangeCallback)
if options['daemon'] and os.fork():
sys.exit(0)
logger.info('pamusb-agent up and running.')
logger.info('Watching device "%s" for user "%s"' % (deviceName, username))
try:
hpDev.run()
except KeyboardInterrupt:
logger.error('Caught keyboard interruption, exiting...')