vpn_l2tp.py
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vpn_l2tp.py
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	#!/usr/bin/env python3
	#
	# Copyright (C) 2019-2020 VyOS maintainers and contributors
	#
	# This program is free software; you can redistribute it and/or modify
	# it under the terms of the GNU General Public License version 2 or later as
	# published by the Free Software Foundation.
	#
	# This program 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, see <http://www.gnu.org/licenses/>.

	import os
	import re

	from copy import deepcopy
	from socket import AF_INET, SOCK_STREAM, socket
	from stat import S_IRUSR, S_IWUSR, S_IRGRP
	from sys import exit
	from time import sleep

	from jinja2 import FileSystemLoader, Environment

	from vyos.config import Config
	from vyos.defaults import directories as vyos_data_dir
	from vyos.util import run
	from vyos.validate import is_ipv4
	from vyos import ConfigError

	pidfile = '/var/run/accel_l2tp.pid'
	l2tp_conf = '/etc/accel-ppp/l2tp/l2tp.config'
	l2tp_chap_secrets = '/etc/accel-ppp/l2tp/chap-secrets'

	default_config_data = {
	'auth_mode': 'local',
	'auth_ppp_mppe': 'prefer',
	'auth_proto': ['auth_mschap_v2'],
	'chap_secrets_file': l2tp_chap_secrets,
	'client_ip_pool': None,
	'client_ip_subnets': [],
	'client_ipv6_pool': {},
	'dnsv4': [],
	'dnsv6': [],
	'gateway_address': '10.255.255.0',
	'local_users' : [],
	'mtu': '1436',
	'outside_addr': '',
	'ppp_mppe': 'prefer',
	'ppp_echo_failure' : '3',
	'ppp_echo_interval' : '30',
	'ppp_echo_timeout': '0',
	'radius_server': [],
	'radius_acct_tmo': '3',
	'radius_max_try': '3',
	'radius_timeout': '3',
	'radius_nas_id': '',
	'radius_nas_ip': '',
	'radius_source_address': '',
	'radius_shaper_attr': '',
	'radius_shaper_vendor': '',
	'radius_dynamic_author': '',
	'wins': [],
	'ip6_column': '',
	'ip6_dp_column': '',
	'ppp_options': {},
	'thread_cnt': 1
	}

	def chk_con():
	"""
	Depending on hardware and threads, daemon needs a little to start if it
	takes longer than 100 * 0.5 secs, exception is being raised not sure if
	that's the best way to check it, but it worked so far quite well
	"""
	cnt = 0
	s = socket(AF_INET, SOCK_STREAM)
	while True:
	try:
	s.connect(("127.0.0.1", 2004))
	break
	except ConnectionRefusedError:
	sleep(0.5)
	cnt += 1
	if cnt == 100:
	raise("failed to start l2tp server")
	break


	def _accel_cmd(command):
	return run(f'/usr/bin/accel-cmd -p 2004 {command}')


	def get_config():
	conf = Config()
	base_path = ['vpn', 'l2tp', 'remote-access']
	if not conf.exists(base_path):
	return None

	conf.set_level(base_path)
	l2tp = deepcopy(default_config_data)

	cpu = os.cpu_count()
	if cpu > 1:
	l2tp['thread_cnt'] = int(cpu/2)

	### general options ###
	if conf.exists(['name-server']):
	for name_server in conf.return_values(['name-server']):
	if is_ipv4(name_server):
	l2tp['dnsv4'].append(name_server)
	else:
	l2tp['dnsv6'].append(name_server)

	if conf.exists(['wins-server']):
	l2tp['wins'] = conf.return_values(['wins-server'])

	if conf.exists('outside-address'):
	l2tp['outside_addr'] = conf.return_value('outside-address')

	if conf.exists(['authentication', 'mode']):
	l2tp['auth_mode'] = conf.return_value(['authentication', 'mode'])

	if conf.exists(['authentication', 'protocols']):
	auth_mods = {
	'pap': 'auth_pap',
	'chap': 'auth_chap_md5',
	'mschap': 'auth_mschap_v1',
	'mschap-v2': 'auth_mschap_v2'
	}

	for proto in conf.return_values(['authentication', 'protocols']):
	l2tp['auth_proto'].append(auth_mods[proto])

	if conf.exists(['authentication', 'mppe']):
	l2tp['auth_ppp_mppe'] = conf.return_value(['authentication', 'mppe'])

	#
	# local auth
	if conf.exists(['authentication', 'local-users']):
	for username in conf.list_nodes(['authentication', 'local-users', 'username']):
	user = {
	'name' : username,
	'password' : '',
	'state' : 'enabled',
	'ip' : '*',
	'upload' : None,
	'download' : None
	}

	conf.set_level(base_path + ['authentication', 'local-users', 'username', username])

	if conf.exists(['password']):
	user['password'] = conf.return_value(['password'])

	if conf.exists(['disable']):
	user['state'] = 'disable'

	if conf.exists(['static-ip']):
	user['ip'] = conf.return_value(['static-ip'])

	if conf.exists(['rate-limit', 'download']):
	user['download'] = conf.return_value(['rate-limit', 'download'])

	if conf.exists(['rate-limit', 'upload']):
	user['upload'] = conf.return_value(['rate-limit', 'upload'])

	l2tp['local_users'].append(user)

	#
	# RADIUS auth and settings
	conf.set_level(base_path + ['authentication', 'radius'])
	if conf.exists(['server']):
	for server in conf.list_nodes(['server']):
	radius = {
	'server' : server,
	'key' : '',
	'fail_time' : 0,
	'port' : '1812'
	}

	conf.set_level(base_path + ['authentication', 'radius', 'server', server])

	if conf.exists(['fail-time']):
	radius['fail-time'] = conf.return_value(['fail-time'])

	if conf.exists(['port']):
	radius['port'] = conf.return_value(['port'])

	if conf.exists(['key']):
	radius['key'] = conf.return_value(['key'])

	if not conf.exists(['disable']):
	l2tp['radius_server'].append(radius)

	#
	# advanced radius-setting
	conf.set_level(base_path + ['authentication', 'radius'])

	if conf.exists(['acct-timeout']):
	l2tp['radius_acct_tmo'] = conf.return_value(['acct-timeout'])

	if conf.exists(['max-try']):
	l2tp['radius_max_try'] = conf.return_value(['max-try'])

	if conf.exists(['timeout']):
	l2tp['radius_timeout'] = conf.return_value(['timeout'])

	if conf.exists(['nas-identifier']):
	l2tp['radius_nas_id'] = conf.return_value(['nas-identifier'])

	if conf.exists(['nas-ip-address']):
	l2tp['radius_nas_ip'] = conf.return_value(['nas-ip-address'])

	if conf.exists(['source-address']):
	l2tp['radius_source_address'] = conf.return_value(['source-address'])

	# Dynamic Authorization Extensions (DOA)/Change Of Authentication (COA)
	if conf.exists(['dynamic-author']):
	dae = {
	'port' : '',
	'server' : '',
	'key' : ''
	}

	if conf.exists(['dynamic-author', 'server']):
	dae['server'] = conf.return_value(['dynamic-author', 'server'])

	if conf.exists(['dynamic-author', 'port']):
	dae['port'] = conf.return_value(['dynamic-author', 'port'])

	if conf.exists(['dynamic-author', 'key']):
	dae['key'] = conf.return_value(['dynamic-author', 'key'])

	l2tp['radius_dynamic_author'] = dae

	if conf.exists(['rate-limit', 'enable']):
	l2tp['radius_shaper_attr'] = 'Filter-Id'
	c_attr = ['rate-limit', 'enable', 'attribute']
	if conf.exists(c_attr):
	l2tp['radius_shaper_attr'] = conf.return_value(c_attr)

	c_vendor = ['rate-limit', 'enable', 'vendor']
	if conf.exists(c_vendor):
	l2tp['radius_shaper_vendor'] = conf.return_value(c_vendor)

	conf.set_level(base_path)
	if conf.exists(['client-ip-pool']):
	if conf.exists(['client-ip-pool', 'start']) and conf.exists(['client-ip-pool', 'stop']):
	start = conf.return_value(['client-ip-pool', 'start'])
	stop = conf.return_value(['client-ip-pool', 'stop'])
	l2tp['client_ip_pool'] = start + '-' + re.search('[0-9]+$', stop).group(0)

	if conf.exists(['client-ip-pool', 'subnet']):
	l2tp['client_ip_subnets'] = conf.return_values(['client-ip-pool', 'subnet'])

	if conf.exists(['client-ipv6-pool', 'prefix']):
	l2tp['client_ipv6_pool']['prefix'] = conf.return_values(
	'client-ipv6-pool prefix')
	l2tp['ip6_column'] = 'ip6,'

	if conf.exists('client-ipv6-pool delegate-prefix'):
	l2tp['client_ipv6_pool']['delegate_prefix'] = conf.return_values(
	'client-ipv6-pool delegate-prefix')
	l2tp['ip6_dp_column'] = 'ip6-dp,'

	if conf.exists('mtu'):
	l2tp['mtu'] = conf.return_value('mtu')

	# gateway address
	if conf.exists('gateway-address'):
	l2tp['gateway_address'] = conf.return_value('gateway-address')
	else:
	# calculate gw-ip-address
	if conf.exists('client-ip-pool start'):
	# use start ip as gw-ip-address
	l2tp['gateway_address'] = conf.return_value(
	'client-ip-pool start')
	elif conf.exists('client-ip-pool subnet'):
	# use first ip address from first defined pool
	lst_ip = re.findall("\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}", conf.return_values(
	'client-ip-pool subnet')[0])
	l2tp['gateway_address'] = lst_ip[0]

	# LNS secret
	if conf.exists(['lns', 'shared-secret']):
	l2tp['lns_shared_secret'] = conf.return_value(['lns', 'shared-secret'])

	if conf.exists(['ccp-disable']):
	l2tp[['ccp_disable']] = True

	# PPP options
	if conf.exists(['idle']):
	l2tp['ppp_echo_timeout'] = conf.return_value(['idle'])

	if conf.exists(['ppp-options', 'lcp-echo-failure']):
	l2tp['ppp_echo_failure'] = conf.return_value(['ppp-options', 'lcp-echo-failure'])

	if conf.exists(['ppp-options', 'lcp-echo-interval']):
	l2tp['ppp_echo_interval'] = conf.return_value(['ppp-options', 'lcp-echo-interval'])

	return l2tp


	def verify(l2tp):
	if not l2tp:
	return None

	if l2tp['auth_mode'] == 'local':
	if not l2tp['local_users']:
	raise ConfigError('L2TP local auth mode requires local users to be configured!')

	for user in l2tp['local_users']:
	if not user['password']:
	raise ConfigError(f"Password required for user {user['name']}")

	elif l2tp['auth_mode'] == 'radius':
	if len(l2tp['radius_server']) == 0:
	raise ConfigError("RADIUS authentication requires at least one server")

	for radius in l2tp['radius_server']:
	if not radius['key']:
	raise ConfigError(f"Missing RADIUS secret for server {{ radius['key'] }}")

	# check for the existence of a client ip pool
	if not (l2tp['client_ip_pool'] or l2tp['client_ip_subnets']):
	raise ConfigError(
	"set vpn l2tp remote-access client-ip-pool requires subnet or start/stop IP pool")

	# check ipv6
	if 'delegate_prefix' in l2tp['client_ipv6_pool'] and not 'prefix' in l2tp['client_ipv6_pool']:
	raise ConfigError(
	"\"set vpn l2tp remote-access client-ipv6-pool prefix\" required for delegate-prefix ")

	if len(l2tp['wins']) > 2:
	raise ConfigError('Not more then two IPv4 WINS name-servers can be configured')

	if len(l2tp['dnsv4']) > 2:
	raise ConfigError('Not more then two IPv4 DNS name-servers can be configured')

	if len(l2tp['dnsv6']) > 3:
	raise ConfigError('Not more then three IPv6 DNS name-servers can be configured')

	return None


	def generate(l2tp):
	if not l2tp:
	return None

	# Create configuration directory if it's non existent
	dirname = os.path.dirname(l2tp_conf)
	if not os.path.isdir(dirname):
	os.mkdir(dirname)

	# Prepare Jinja2 template loader from files
	tmpl_path = os.path.join(vyos_data_dir['data'], 'templates', 'l2tp')
	fs_loader = FileSystemLoader(tmpl_path)
	env = Environment(loader=fs_loader, trim_blocks=True)

	tmpl = env.get_template('l2tp.config.tmpl')
	config_text = tmpl.render(c)
	with open(l2tp_conf, 'w') as f:
	f.write(config_text)

	if l2tp['auth_mode'] == 'local':
	tmpl = env.get_template('chap-secrets.tmpl')
	config_text = tmpl.render(l2tp)
	with open(l2tp['chap_secrets_file'], 'w') as f:
	f.write(config_text)

	os.chmod(l2tp['chap_secrets_file'], S_IRUSR \| S_IWUSR \| S_IRGRP)

	else:
	if os.path.exists(l2tp['chap_secrets_file']):
	os.unlink(l2tp['chap_secrets_file'])

	return None


	def apply(l2tp):
	if not l2tp:
	if os.path.exists(pidfile):
	_accel_cmd('shutdown hard')
	if os.path.exists(pidfile):
	os.remove(pidfile)
	return None

	if not os.path.exists(pidfile):
	ret = run(f'/usr/sbin/accel-pppd -c {l2tp_conf} -p {pidfile} -d')
	chk_con()
	if ret != 0 and os.path.exists(pidfile):
	os.remove(pidfile)
	raise ConfigError('accel-pppd failed to start')
	else:
	# if gw ip changes, only restart doesn't work
	_accel_cmd('restart')


	if __name__ == '__main__':
	try:
	c = get_config()
	verify(c)
	generate(c)
	apply(c)
	except ConfigError as e:
	print(e)
	exit(1)

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