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#!/usr/bin/env python3
#
# Copyright (C) 2021-2023 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
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.utils.dict import dict_search_args
from vyos.utils.process import cmd
from vyos.utils.process import run
from vyos import ConfigError
from vyos import airbag
airbag.enable()
mark_offset = 0x7FFFFFFF
nftables_conf = '/run/nftables_policy.conf'
valid_groups = [
'address_group',
'domain_group',
'network_group',
'port_group',
'interface_group'
]
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)
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 len({'address_group', 'domain_group', 'network_group'} & set(side_conf['group'])) > 1:
raise ConfigError('Only one address-group, domain-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)
return None
def generate(policy):
if not os.path.exists(nftables_conf):
policy['first_install'] = True
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)
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