diff options
Diffstat (limited to 'src/conf_mode/policy-route.py')
| -rwxr-xr-x | src/conf_mode/policy-route.py | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/src/conf_mode/policy-route.py b/src/conf_mode/policy-route.py new file mode 100755 index 000000000..5de341beb --- /dev/null +++ b/src/conf_mode/policy-route.py @@ -0,0 +1,262 @@ +#!/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 run +from vyos import ConfigError +from vyos import airbag +airbag.enable() + +mark_offset = 0x7FFFFFFF +nftables_conf = '/run/nftables_policy.conf' + +preserve_chains = [ + 'VYOS_PBR_PREROUTING', + 'VYOS_PBR_POSTROUTING', + 'VYOS_PBR6_PREROUTING', + 'VYOS_PBR6_POSTROUTING' +] + +valid_groups = [ + 'address_group', + 'network_group', + '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): + 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) + + 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_rule(table, jump_chain): + commands = [] + results = cmd(f'nft -a list table {table}').split("\n") + for line in results: + if f'jump {jump_chain}' in line: + handle_search = re.search('handle (\d+)', line) + if handle_search: + commands.append(f'delete rule {table} {chain} handle {handle_search[1]}') + return commands + +def cleanup_commands(policy): + commands = [] + for table in ['ip mangle', 'ip6 mangle']: + 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: + chain = item['chain']['name'] + if not chain.startswith("VYOS_PBR"): + continue + if chain not in preserve_chains: + if table == 'ip mangle' and dict_search_args(policy, 'route', chain.replace("VYOS_PBR_", "", 1)): + commands.append(f'flush chain {table} {chain}') + elif table == 'ip6 mangle' and dict_search_args(policy, 'route6', chain.replace("VYOS_PBR6_", "", 1)): + commands.append(f'flush chain {table} {chain}') + else: + commands += cleanup_rule(table, chain) + commands.append(f'delete chain {table} {chain}') + return commands + +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) |