firewall.py
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firewall.py
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	#!/usr/bin/env python3
	#
	# Copyright (C) 2021-2022 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 glob import glob
	from json import loads
	from sys import exit

	from vyos.base import Warning
	from vyos.config import Config
	from vyos.configdict import dict_merge
	from vyos.configdict import node_changed
	from vyos.configdiff import get_config_diff, Diff
	# from vyos.configverify import verify_interface_exists
	from vyos.firewall import fqdn_config_parse
	from vyos.firewall import geoip_update
	from vyos.template import render
	from vyos.util import call
	from vyos.util import cmd
	from vyos.util import dict_search_args
	from vyos.util import dict_search_recursive
	from vyos.util import process_named_running
	from vyos.util import rc_cmd
	from vyos.xml import defaults
	from vyos import ConfigError
	from vyos import airbag
	airbag.enable()

	nat_conf_script = '/usr/libexec/vyos/conf_mode/nat.py'
	policy_route_conf_script = '/usr/libexec/vyos/conf_mode/policy-route.py'

	nftables_conf = '/run/nftables.conf'

	sysfs_config = {
	'all_ping': {'sysfs': '/proc/sys/net/ipv4/icmp_echo_ignore_all', 'enable': '0', 'disable': '1'},
	'broadcast_ping': {'sysfs': '/proc/sys/net/ipv4/icmp_echo_ignore_broadcasts', 'enable': '0', 'disable': '1'},
	'ip_src_route': {'sysfs': '/proc/sys/net/ipv4/conf/*/accept_source_route'},
	'ipv6_receive_redirects': {'sysfs': '/proc/sys/net/ipv6/conf/*/accept_redirects'},
	'ipv6_src_route': {'sysfs': '/proc/sys/net/ipv6/conf/*/accept_source_route', 'enable': '0', 'disable': '-1'},
	'log_martians': {'sysfs': '/proc/sys/net/ipv4/conf/all/log_martians'},
	'receive_redirects': {'sysfs': '/proc/sys/net/ipv4/conf/*/accept_redirects'},
	'send_redirects': {'sysfs': '/proc/sys/net/ipv4/conf/*/send_redirects'},
	'source_validation': {'sysfs': '/proc/sys/net/ipv4/conf/*/rp_filter', 'disable': '0', 'strict': '1', 'loose': '2'},
	'syn_cookies': {'sysfs': '/proc/sys/net/ipv4/tcp_syncookies'},
	'twa_hazards_protection': {'sysfs': '/proc/sys/net/ipv4/tcp_rfc1337'}
	}

	valid_groups = [
	'address_group',
	'domain_group',
	'network_group',
	'port_group'
	]

	nested_group_types = [
	'address_group', 'network_group', 'mac_group',
	'port_group', 'ipv6_address_group', 'ipv6_network_group'
	]

	snmp_change_type = {
	'unknown': 0,
	'add': 1,
	'delete': 2,
	'change': 3
	}
	snmp_event_source = 1
	snmp_trap_mib = 'VYATTA-TRAP-MIB'
	snmp_trap_name = 'mgmtEventTrap'

	def geoip_updated(conf, firewall):
	diff = get_config_diff(conf)
	node_diff = diff.get_child_nodes_diff(['firewall'], expand_nodes=Diff.DELETE, recursive=True)

	out = {
	'name': [],
	'ipv6_name': [],
	'deleted_name': [],
	'deleted_ipv6_name': []
	}
	updated = False

	for key, path in dict_search_recursive(firewall, 'geoip'):
	set_name = f'GEOIP_CC_{path[1]}_{path[3]}'
	if path[0] == 'name':
	out['name'].append(set_name)
	elif path[0] == 'ipv6_name':
	out['ipv6_name'].append(set_name)
	updated = True

	if 'delete' in node_diff:
	for key, path in dict_search_recursive(node_diff['delete'], 'geoip'):
	set_name = f'GEOIP_CC_{path[1]}_{path[3]}'
	if path[0] == 'name':
	out['deleted_name'].append(set_name)
	elif path[0] == 'ipv6-name':
	out['deleted_ipv6_name'].append(set_name)
	updated = True

	if updated:
	return out

	return False

	def get_config(config=None):
	if config:
	conf = config
	else:
	conf = Config()
	base = ['firewall']

	firewall = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True,
	no_tag_node_value_mangle=True)

	# We have gathered the dict representation of the CLI, but there are
	# default options which we need to update into the dictionary retrived.
	# XXX: T2665: we currently have no nice way for defaults under tag
	# nodes, thus we load the defaults "by hand"
	default_values = defaults(base)
	for tmp in ['name', 'ipv6_name']:
	if tmp in default_values:
	del default_values[tmp]

	if 'zone' in default_values:
	del default_values['zone']

	firewall = dict_merge(default_values, firewall)

	# Merge in defaults for IPv4 ruleset
	if 'name' in firewall:
	default_values = defaults(base + ['name'])
	for name in firewall['name']:
	firewall['name'][name] = dict_merge(default_values,
	firewall['name'][name])

	# Merge in defaults for IPv6 ruleset
	if 'ipv6_name' in firewall:
	default_values = defaults(base + ['ipv6-name'])
	for ipv6_name in firewall['ipv6_name']:
	firewall['ipv6_name'][ipv6_name] = dict_merge(default_values,
	firewall['ipv6_name'][ipv6_name])

	if 'zone' in firewall:
	default_values = defaults(base + ['zone'])
	for zone in firewall['zone']:
	firewall['zone'][zone] = dict_merge(default_values, firewall['zone'][zone])

	firewall['group_resync'] = bool('group' in firewall or node_changed(conf, base + ['group']))

	if 'config_trap' in firewall and firewall['config_trap'] == 'enable':
	diff = get_config_diff(conf)
	firewall['trap_diff'] = diff.get_child_nodes_diff_str(base)
	firewall['trap_targets'] = conf.get_config_dict(['service', 'snmp', 'trap-target'],
	key_mangling=('-', '_'), get_first_key=True,
	no_tag_node_value_mangle=True)

	firewall['geoip_updated'] = geoip_updated(conf, firewall)

	fqdn_config_parse(firewall)

	return firewall

	def verify_rule(firewall, rule_conf, ipv6):
	if 'action' not in rule_conf:
	raise ConfigError('Rule action must be defined')

	if 'jump' in rule_conf['action'] and 'jump_target' not in rule_conf:
	raise ConfigError('Action set to jump, but no jump-target specified')

	if 'jump_target' in rule_conf:
	if 'jump' not in rule_conf['action']:
	raise ConfigError('jump-target defined, but action jump needed and it is not defined')
	target = rule_conf['jump_target']
	if not ipv6:
	if target not in dict_search_args(firewall, 'name'):
	raise ConfigError(f'Invalid jump-target. Firewall name {target} does not exist on the system')
	else:
	if target not in dict_search_args(firewall, 'ipv6_name'):
	raise ConfigError(f'Invalid jump-target. Firewall ipv6-name {target} does not exist on the system')

	if 'fragment' in rule_conf:
	if {'match_frag', 'match_non_frag'} <= set(rule_conf['fragment']):
	raise ConfigError('Cannot specify both "match-frag" and "match-non-frag"')

	if 'limit' in rule_conf:
	if 'rate' in rule_conf['limit']:
	rate_int = re.sub(r'\D', '', rule_conf['limit']['rate'])
	if int(rate_int) < 1:
	raise ConfigError('Limit rate integer cannot be less than 1')

	if 'ipsec' in rule_conf:
	if {'match_ipsec', 'match_non_ipsec'} <= set(rule_conf['ipsec']):
	raise ConfigError('Cannot specify both "match-ipsec" and "match-non-ipsec"')

	if 'recent' in rule_conf:
	if not {'count', 'time'} <= set(rule_conf['recent']):
	raise ConfigError('Recent "count" and "time" values must be defined')

	tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags')
	if tcp_flags:
	if dict_search_args(rule_conf, 'protocol') != 'tcp':
	raise ConfigError('Protocol must be tcp when specifying tcp flags')

	not_flags = dict_search_args(rule_conf, 'tcp', 'flags', 'not')
	if not_flags:
	duplicates = [flag for flag in tcp_flags if flag in not_flags]
	if duplicates:
	raise ConfigError(f'Cannot match a tcp flag as set and not set')

	if 'protocol' in rule_conf:
	if rule_conf['protocol'] == 'icmp' and ipv6:
	raise ConfigError(f'Cannot match IPv4 ICMP protocol on IPv6, use ipv6-icmp')
	if rule_conf['protocol'] == 'ipv6-icmp' and not ipv6:
	raise ConfigError(f'Cannot match IPv6 ICMP protocol on IPv4, use icmp')

	for side in ['destination', 'source']:
	if side in rule_conf:
	side_conf = rule_conf[side]

	if len({'address', 'fqdn', 'geoip'} & set(side_conf)) > 1:
	raise ConfigError('Only one of address, fqdn or geoip can be specified')

	if 'group' in side_conf:
	if len({'address_group', 'network_group', 'domain_group'} & set(side_conf['group'])) > 1:
	raise ConfigError('Only one address-group, network-group or domain-group can be specified')

	for group in valid_groups:
	if group in side_conf['group']:
	group_name = side_conf['group'][group]

	fw_group = f'ipv6_{group}' if ipv6 and group in ['address_group', 'network_group'] else group
	error_group = fw_group.replace("_", "-")

	if group in ['address_group', 'network_group', 'domain_group']:
	types = [t for t in ['address', 'fqdn', 'geoip'] if t in side_conf]
	if types:
	raise ConfigError(f'{error_group} and {types[0]} cannot both be defined')

	if group_name and group_name[0] == '!':
	group_name = group_name[1:]

	group_obj = dict_search_args(firewall, 'group', fw_group, group_name)

	if group_obj is None:
	raise ConfigError(f'Invalid {error_group} "{group_name}" on firewall rule')

	if not group_obj:
	Warning(f'{error_group} "{group_name}" has no members!')

	if 'port' in side_conf or dict_search_args(side_conf, 'group', 'port_group'):
	if 'protocol' not in rule_conf:
	raise ConfigError('Protocol must be defined if specifying a port or port-group')

	if rule_conf['protocol'] not in ['tcp', 'udp', 'tcp_udp']:
	raise ConfigError('Protocol must be tcp, udp, or tcp_udp when specifying a port or port-group')

	def verify_nested_group(group_name, group, groups, seen):
	if 'include' not in group:
	return

	for g in group['include']:
	if g not in groups:
	raise ConfigError(f'Nested group "{g}" does not exist')

	if g in seen:
	raise ConfigError(f'Group "{group_name}" has a circular reference')

	seen.append(g)

	if 'include' in groups[g]:
	verify_nested_group(g, groups[g], groups, seen)

	def verify(firewall):
	if 'config_trap' in firewall and firewall['config_trap'] == 'enable':
	if not firewall['trap_targets']:
	raise ConfigError(f'Firewall config-trap enabled but "service snmp trap-target" is not defined')

	if 'group' in firewall:
	for group_type in nested_group_types:
	if group_type in firewall['group']:
	groups = firewall['group'][group_type]
	for group_name, group in groups.items():
	verify_nested_group(group_name, group, groups, [])

	for name in ['name', 'ipv6_name']:
	if name in firewall:
	for name_id, name_conf in firewall[name].items():
	if 'jump' in name_conf['default_action'] and 'default_jump_target' not in name_conf:
	raise ConfigError('default-action set to jump, but no default-jump-target specified')
	if 'default_jump_target' in name_conf:
	target = name_conf['default_jump_target']
	if 'jump' not in name_conf['default_action']:
	raise ConfigError('default-jump-target defined,but default-action jump needed and it is not defined')
	if name_conf['default_jump_target'] == name_id:
	raise ConfigError(f'Loop detected on default-jump-target.')
	## Now need to check that default-jump-target exists (other firewall chain/name)
	if target not in dict_search_args(firewall, name):
	raise ConfigError(f'Invalid jump-target. Firewall {name} {target} does not exist on the system')

	if 'rule' in name_conf:
	for rule_id, rule_conf in name_conf['rule'].items():
	verify_rule(firewall, rule_conf, name == 'ipv6_name')

	if 'interface' in firewall:
	for ifname, if_firewall in firewall['interface'].items():
	# verify ifname needs to be disabled, dynamic devices come up later
	# verify_interface_exists(ifname)

	for direction in ['in', 'out', 'local']:
	name = dict_search_args(if_firewall, direction, 'name')
	ipv6_name = dict_search_args(if_firewall, direction, 'ipv6_name')

	if name and dict_search_args(firewall, 'name', name) == None:
	raise ConfigError(f'Invalid firewall name "{name}" referenced on interface {ifname}')

	if ipv6_name and dict_search_args(firewall, 'ipv6_name', ipv6_name) == None:
	raise ConfigError(f'Invalid firewall ipv6-name "{ipv6_name}" referenced on interface {ifname}')

	local_zone = False
	zone_interfaces = []

	if 'zone' in firewall:
	for zone, zone_conf in firewall['zone'].items():
	if 'local_zone' not in zone_conf and 'interface' not in zone_conf:
	raise ConfigError(f'Zone "{zone}" has no interfaces and is not the local zone')

	if 'local_zone' in zone_conf:
	if local_zone:
	raise ConfigError('There cannot be multiple local zones')
	if 'interface' in zone_conf:
	raise ConfigError('Local zone cannot have interfaces assigned')
	if 'intra_zone_filtering' in zone_conf:
	raise ConfigError('Local zone cannot use intra-zone-filtering')
	local_zone = True

	if 'interface' in zone_conf:
	found_duplicates = [intf for intf in zone_conf['interface'] if intf in zone_interfaces]

	if found_duplicates:
	raise ConfigError(f'Interfaces cannot be assigned to multiple zones')

	zone_interfaces += zone_conf['interface']

	if 'intra_zone_filtering' in zone_conf:
	intra_zone = zone_conf['intra_zone_filtering']

	if len(intra_zone) > 1:
	raise ConfigError('Only one intra-zone-filtering action must be specified')

	if 'firewall' in intra_zone:
	v4_name = dict_search_args(intra_zone, 'firewall', 'name')
	if v4_name and not dict_search_args(firewall, 'name', v4_name):
	raise ConfigError(f'Firewall name "{v4_name}" does not exist')

	v6_name = dict_search_args(intra_zone, 'firewall', 'ipv6_name')
	if v6_name and not dict_search_args(firewall, 'ipv6_name', v6_name):
	raise ConfigError(f'Firewall ipv6-name "{v6_name}" does not exist')

	if not v4_name and not v6_name:
	raise ConfigError('No firewall names specified for intra-zone-filtering')

	if 'from' in zone_conf:
	for from_zone, from_conf in zone_conf['from'].items():
	if from_zone not in firewall['zone']:
	raise ConfigError(f'Zone "{zone}" refers to a non-existent or deleted zone "{from_zone}"')

	v4_name = dict_search_args(from_conf, 'firewall', 'name')
	if v4_name and not dict_search_args(firewall, 'name', v4_name):
	raise ConfigError(f'Firewall name "{v4_name}" does not exist')

	v6_name = dict_search_args(from_conf, 'firewall', 'ipv6_name')
	if v6_name and not dict_search_args(firewall, 'ipv6_name', v6_name):
	raise ConfigError(f'Firewall ipv6-name "{v6_name}" does not exist')

	return None

	def generate(firewall):
	if not os.path.exists(nftables_conf):
	firewall['first_install'] = True

	if 'zone' in firewall:
	for local_zone, local_zone_conf in firewall['zone'].items():
	if 'local_zone' not in local_zone_conf:
	continue

	local_zone_conf['from_local'] = {}

	for zone, zone_conf in firewall['zone'].items():
	if zone == local_zone or 'from' not in zone_conf:
	continue
	if local_zone in zone_conf['from']:
	local_zone_conf['from_local'][zone] = zone_conf['from'][local_zone]

	render(nftables_conf, 'firewall/nftables.j2', firewall)
	return None

	def apply_sysfs(firewall):
	for name, conf in sysfs_config.items():
	paths = glob(conf['sysfs'])
	value = None

	if name in firewall:
	conf_value = firewall[name]

	if conf_value in conf:
	value = conf[conf_value]
	elif conf_value == 'enable':
	value = '1'
	elif conf_value == 'disable':
	value = '0'

	if value:
	for path in paths:
	with open(path, 'w') as f:
	f.write(value)

	def post_apply_trap(firewall):
	if 'first_install' in firewall:
	return None

	if 'config_trap' not in firewall or firewall['config_trap'] != 'enable':
	return None

	if not process_named_running('snmpd'):
	return None

	trap_username = os.getlogin()

	for host, target_conf in firewall['trap_targets'].items():
	community = target_conf['community'] if 'community' in target_conf else 'public'
	port = int(target_conf['port']) if 'port' in target_conf else 162

	base_cmd = f'snmptrap -v2c -c {community} {host}:{port} 0 {snmp_trap_mib}::{snmp_trap_name} '

	for change_type, changes in firewall['trap_diff'].items():
	for path_str, value in changes.items():
	objects = [
	f'mgmtEventUser s "{trap_username}"',
	f'mgmtEventSource i {snmp_event_source}',
	f'mgmtEventType i {snmp_change_type[change_type]}'
	]

	if change_type == 'add':
	objects.append(f'mgmtEventCurrCfg s "{path_str} {value}"')
	elif change_type == 'delete':
	objects.append(f'mgmtEventPrevCfg s "{path_str} {value}"')
	elif change_type == 'change':
	objects.append(f'mgmtEventPrevCfg s "{path_str} {value[0]}"')
	objects.append(f'mgmtEventCurrCfg s "{path_str} {value[1]}"')

	cmd(base_cmd + ' '.join(objects))

	def resync_nat():
	# Update nat as firewall groups were updated
	tmp, out = rc_cmd(nat_conf_script)
	if tmp > 0:
	Warning(f'Failed to re-apply nat configuration! {out}')

	def resync_policy_route():
	# Update policy route as firewall groups were updated
	tmp, out = rc_cmd(policy_route_conf_script)
	if tmp > 0:
	Warning(f'Failed to re-apply policy route configuration! {out}')

	def apply(firewall):
	install_result, output = rc_cmd(f'nft -f {nftables_conf}')
	if install_result == 1:
	raise ConfigError(f'Failed to apply firewall: {output}')

	apply_sysfs(firewall)

	if firewall['group_resync']:
	resync_nat()
	resync_policy_route()

	# T970 Enable a resolver (systemd daemon) that checks
	# domain-group/fqdn addresses and update entries for domains by timeout
	# If router loaded without internet connection or for synchronization
	domain_action = 'stop'
	if dict_search_args(firewall, 'group', 'domain_group') or firewall['ip_fqdn'] or firewall['ip6_fqdn']:
	domain_action = 'restart'
	call(f'systemctl {domain_action} vyos-domain-resolver.service')

	if firewall['geoip_updated']:
	# Call helper script to Update set contents
	if 'name' in firewall['geoip_updated'] or 'ipv6_name' in firewall['geoip_updated']:
	print('Updating GeoIP. Please wait...')
	geoip_update(firewall)

	post_apply_trap(firewall)

	return None

	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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