#!/usr/bin/env python3 # # Copyright (C) 2021 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 . import os from glob import glob from json import loads from sys import exit from vyos.config import Config from vyos.configdict import dict_merge from vyos.configdiff import get_config_diff, Diff from vyos.template import render from vyos.util import cmd from vyos.util import dict_search_args from vyos.util import process_named_running from vyos.util import run from vyos.xml import defaults from vyos import ConfigError from vyos import airbag airbag.enable() 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'} } preserve_chains = [ 'INPUT', 'FORWARD', 'OUTPUT', 'VYOS_FW_IN', 'VYOS_FW_OUT', 'VYOS_FW_LOCAL', 'VYOS_FW_OUTPUT', 'VYOS_POST_FW', 'VYOS_FRAG_MARK', 'VYOS_FW6_IN', 'VYOS_FW6_OUT', 'VYOS_FW6_LOCAL', 'VYOS_FW6_OUTPUT', 'VYOS_POST_FW6', 'VYOS_FRAG6_MARK' ] valid_groups = [ 'address_group', 'network_group', 'port_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 get_firewall_interfaces(conf): out = {} interfaces = conf.get_config_dict(['interfaces'], key_mangling=('-', '_'), get_first_key=True, no_tag_node_value_mangle=True) def find_interfaces(iftype_conf, output={}, prefix=''): for ifname, if_conf in iftype_conf.items(): if 'firewall' in if_conf: output[prefix + ifname] = if_conf['firewall'] for vif in ['vif', 'vif_s', 'vif_c']: if vif in if_conf: output.update(find_interfaces(if_conf[vif], output, f'{prefix}{ifname}.')) return output for iftype, iftype_conf in interfaces.items(): out.update(find_interfaces(iftype_conf)) return out def get_config(config=None): if config: conf = config else: conf = Config() base = ['firewall'] if not conf.exists(base): return {} firewall = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True, no_tag_node_value_mangle=True) default_values = defaults(base) firewall = dict_merge(default_values, firewall) firewall['interfaces'] = get_firewall_interfaces(conf) 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) return firewall def verify_rule(firewall, rule_conf, ipv6): if 'action' not in rule_conf: raise ConfigError('Rule action must be defined') 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 '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') for side in ['destination', 'source']: if side in rule_conf: side_conf = rule_conf[side] if 'group' in side_conf: if {'address_group', 'network_group'} <= set(side_conf['group']): raise ConfigError('Only one address-group or network-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 if not dict_search_args(firewall, 'group', fw_group): error_group = fw_group.replace("_", "-") raise ConfigError(f'Group defined in rule but {error_group} is not configured') if group_name not in firewall['group'][fw_group]: error_group = group.replace("_", "-") raise ConfigError(f'Invalid {error_group} "{group_name}" on firewall rule') 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(firewall): # bail out early - looks like removal from running config if not firewall: return None 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') for name in ['name', 'ipv6_name']: if name in firewall: for name_id, name_conf in firewall[name].items(): if name_id in preserve_chains: raise ConfigError(f'Firewall name "{name_id}" is reserved for VyOS') if 'rule' in name_conf: for rule_id, rule_conf in name_conf['rule'].items(): verify_rule(firewall, rule_conf, name == 'ipv6_name') for ifname, if_firewall in firewall['interfaces'].items(): 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 not dict_search_args(firewall, 'name', name): raise ConfigError(f'Firewall name "{name}" is still referenced on interface {ifname}') if ipv6_name and not dict_search_args(firewall, 'ipv6_name', ipv6_name): raise ConfigError(f'Firewall ipv6-name "{ipv6_name}" is still referenced on interface {ifname}') return None def cleanup_commands(firewall): commands = [] for table in ['ip filter', 'ip6 filter']: state_chain = 'VYOS_STATE_POLICY' if table == 'ip filter' else 'VYOS_STATE_POLICY6' json_str = cmd(f'nft -j list table {table}') obj = loads(json_str) if 'nftables' not in obj: continue for item in obj['nftables']: if 'chain' in item: if item['chain']['name'] in ['VYOS_STATE_POLICY', 'VYOS_STATE_POLICY6']: chain = item['chain']['name'] if 'state_policy' not in firewall: commands.append(f'delete chain {table} {chain}') else: commands.append(f'flush chain {table} {chain}') elif item['chain']['name'] not in preserve_chains: chain = item['chain']['name'] if table == 'ip filter' and dict_search_args(firewall, 'name', chain): commands.append(f'flush chain {table} {chain}') elif table == 'ip6 filter' and dict_search_args(firewall, 'ipv6_name', chain): commands.append(f'flush chain {table} {chain}') else: commands.append(f'delete chain {table} {chain}') elif 'rule' in item: rule = item['rule'] if rule['chain'] in ['VYOS_FW_IN', 'VYOS_FW_OUTPUT', 'VYOS_FW_LOCAL', 'VYOS_FW6_IN', 'VYOS_FW6_OUTPUT', 'VYOS_FW6_LOCAL']: if 'expr' in rule and any([True for expr in rule['expr'] if dict_search_args(expr, 'jump', 'target') == state_chain]): if 'state_policy' not in firewall: chain = rule['chain'] handle = rule['handle'] commands.append(f'delete rule {table} {chain} handle {handle}') return commands def generate(firewall): if not os.path.exists(nftables_conf): firewall['first_install'] = True else: firewall['cleanup_commands'] = cleanup_commands(firewall) render(nftables_conf, 'firewall/nftables.tmpl', 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 state_policy_rule_exists(): # Determine if state policy rules already exist in nft search_str = cmd(f'nft list chain ip filter VYOS_FW_IN') return 'VYOS_STATE_POLICY' in search_str def apply(firewall): if 'first_install' in firewall: run('nfct helper add rpc inet tcp') run('nfct helper add rpc inet udp') run('nfct helper add tns inet tcp') install_result = run(f'nft -f {nftables_conf}') if install_result == 1: raise ConfigError('Failed to apply firewall') if 'state_policy' in firewall and not state_policy_rule_exists(): for chain in ['VYOS_FW_IN', 'VYOS_FW_OUTPUT', 'VYOS_FW_LOCAL']: cmd(f'nft insert rule ip filter {chain} jump VYOS_STATE_POLICY') for chain in ['VYOS_FW6_IN', 'VYOS_FW6_OUTPUT', 'VYOS_FW6_LOCAL']: cmd(f'nft insert rule ip6 filter {chain} jump VYOS_STATE_POLICY6') apply_sysfs(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)