#!/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 <http://www.gnu.org/licenses/>. import os import re from json import loads from sys import exit from vyos.base import Warning from vyos.config import Config from vyos.template import render from vyos.util import cmd from vyos.util import dict_search_args from vyos.util import dict_search_recursive from vyos.util import run from vyos import ConfigError from vyos import airbag airbag.enable() mark_offset = 0x7FFFFFFF nftables_conf = '/run/nftables_policy.conf' ROUTE_PREFIX = 'VYOS_PBR_' ROUTE6_PREFIX = 'VYOS_PBR6_' preserve_chains = [ 'VYOS_PBR_PREROUTING', 'VYOS_PBR_POSTROUTING', 'VYOS_PBR6_PREROUTING', 'VYOS_PBR6_POSTROUTING' ] valid_groups = [ 'address_group', 'network_group', 'port_group' ] group_set_prefix = { 'A_': 'address_group', 'A6_': 'ipv6_address_group', # 'D_': 'domain_group', 'M_': 'mac_group', 'N_': 'network_group', 'N6_': 'ipv6_network_group', 'P_': 'port_group' } def get_policy_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 'policy' in if_conf: output[prefix + ifname] = if_conf['policy'] 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 = ['policy'] policy = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True, no_tag_node_value_mangle=True) policy['firewall_group'] = conf.get_config_dict(['firewall', 'group'], key_mangling=('-', '_'), get_first_key=True, no_tag_node_value_mangle=True) policy['interfaces'] = get_policy_interfaces(conf) return policy def verify_rule(policy, name, rule_conf, ipv6, rule_id): icmp = 'icmp' if not ipv6 else 'icmpv6' if icmp in rule_conf: icmp_defined = False if 'type_name' in rule_conf[icmp]: icmp_defined = True if 'code' in rule_conf[icmp] or 'type' in rule_conf[icmp]: raise ConfigError(f'{name} rule {rule_id}: Cannot use ICMP type/code with ICMP type-name') if 'code' in rule_conf[icmp]: icmp_defined = True if 'type' not in rule_conf[icmp]: raise ConfigError(f'{name} rule {rule_id}: ICMP code can only be defined if ICMP type is defined') if 'type' in rule_conf[icmp]: icmp_defined = True if icmp_defined and 'protocol' not in rule_conf or rule_conf['protocol'] != icmp: raise ConfigError(f'{name} rule {rule_id}: ICMP type/code or type-name can only be defined if protocol is ICMP') if 'set' in rule_conf: if 'tcp_mss' in rule_conf['set']: tcp_flags = dict_search_args(rule_conf, 'tcp', 'flags') if not tcp_flags or 'syn' not in tcp_flags: raise ConfigError(f'{name} rule {rule_id}: TCP SYN flag must be set to modify TCP-MSS') 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') 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] if group_name.startswith('!'): group_name = group_name[1:] fw_group = f'ipv6_{group}' if ipv6 and group in ['address_group', 'network_group'] else group error_group = fw_group.replace("_", "-") group_obj = dict_search_args(policy['firewall_group'], fw_group, group_name) if group_obj is None: raise ConfigError(f'Invalid {error_group} "{group_name}" on policy route 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(policy): for route in ['route', 'route6']: ipv6 = route == 'route6' if route in policy: for name, pol_conf in policy[route].items(): if 'rule' in pol_conf: for rule_id, rule_conf in pol_conf['rule'].items(): verify_rule(policy, name, rule_conf, ipv6, rule_id) for ifname, if_policy in policy['interfaces'].items(): name = dict_search_args(if_policy, 'route') ipv6_name = dict_search_args(if_policy, 'route6') if name and not dict_search_args(policy, 'route', name): raise ConfigError(f'Policy route "{name}" is still referenced on interface {ifname}') if ipv6_name and not dict_search_args(policy, 'route6', ipv6_name): raise ConfigError(f'Policy route6 "{ipv6_name}" is still referenced on interface {ifname}') return None def cleanup_commands(policy): commands = [] commands_chains = [] commands_sets = [] for table in ['ip mangle', 'ip6 mangle']: route_node = 'route' if table == 'ip mangle' else 'route6' chain_prefix = ROUTE_PREFIX if table == 'ip mangle' else ROUTE6_PREFIX json_str = cmd(f'nft -t -j list table {table}') obj = loads(json_str) if 'nftables' not in obj: continue for item in obj['nftables']: if 'chain' in item: chain = item['chain']['name'] if chain in preserve_chains or not chain.startswith("VYOS_PBR"): continue if dict_search_args(policy, route_node, chain.replace(chain_prefix, "", 1)) != None: commands.append(f'flush chain {table} {chain}') else: commands_chains.append(f'delete chain {table} {chain}') if 'rule' in item: rule = item['rule'] chain = rule['chain'] handle = rule['handle'] if chain not in preserve_chains: continue target, _ = next(dict_search_recursive(rule['expr'], 'target')) if target.startswith(chain_prefix): if dict_search_args(policy, route_node, target.replace(chain_prefix, "", 1)) == None: commands.append(f'delete rule {table} {chain} handle {handle}') if 'set' in item: set_name = item['set']['name'] for prefix, group_type in group_set_prefix.items(): if set_name.startswith(prefix): group_name = set_name.replace(prefix, "", 1) if dict_search_args(policy, 'firewall_group', group_type, group_name) != None: commands_sets.append(f'flush set {table} {set_name}') else: commands_sets.append(f'delete set {table} {set_name}') return commands + commands_chains + commands_sets def generate(policy): if not os.path.exists(nftables_conf): policy['first_install'] = True else: policy['cleanup_commands'] = cleanup_commands(policy) render(nftables_conf, 'firewall/nftables-policy.j2', policy) return None def apply_table_marks(policy): for route in ['route', 'route6']: if route in policy: cmd_str = 'ip' if route == 'route' else 'ip -6' tables = [] for name, pol_conf in policy[route].items(): if 'rule' in pol_conf: for rule_id, rule_conf in pol_conf['rule'].items(): set_table = dict_search_args(rule_conf, 'set', 'table') if set_table: if set_table == 'main': set_table = '254' if set_table in tables: continue tables.append(set_table) table_mark = mark_offset - int(set_table) cmd(f'{cmd_str} rule add pref {set_table} fwmark {table_mark} table {set_table}') def cleanup_table_marks(): for cmd_str in ['ip', 'ip -6']: json_rules = cmd(f'{cmd_str} -j -N rule list') rules = loads(json_rules) for rule in rules: if 'fwmark' not in rule or 'table' not in rule: continue fwmark = rule['fwmark'] table = int(rule['table']) if fwmark[:2] == '0x': fwmark = int(fwmark, 16) if (int(fwmark) == (mark_offset - table)): cmd(f'{cmd_str} rule del fwmark {fwmark} table {table}') def apply(policy): install_result = run(f'nft -f {nftables_conf}') if install_result == 1: raise ConfigError('Failed to apply policy based routing') if 'first_install' not in policy: cleanup_table_marks() apply_table_marks(policy) return None if __name__ == '__main__': try: c = get_config() verify(c) generate(c) apply(c) except ConfigError as e: print(e) exit(1)