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firewall-interface.py
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firewall-interface.py
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#!/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 sys import argv
from sys import exit
from vyos.config import Config
from vyos.configdict import leaf_node_changed
from vyos.ifconfig import Section
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()
NAME_PREFIX = 'NAME_'
NAME6_PREFIX = 'NAME6_'
NFT_CHAINS = {
'in': 'VYOS_FW_FORWARD',
'out': 'VYOS_FW_FORWARD',
'local': 'VYOS_FW_LOCAL'
}
NFT6_CHAINS = {
'in': 'VYOS_FW6_FORWARD',
'out': 'VYOS_FW6_FORWARD',
'local': 'VYOS_FW6_LOCAL'
}
def get_config(config=None):
if config:
conf = config
else:
conf = Config()
ifname = argv[1]
ifpath = Section.get_config_path(ifname)
if_firewall_path = f'interfaces {ifpath} firewall'
if_firewall = conf.get_config_dict(if_firewall_path, key_mangling=('-', '_'), get_first_key=True,
no_tag_node_value_mangle=True)
if_firewall['ifname'] = ifname
if_firewall['firewall'] = conf.get_config_dict(['firewall'], key_mangling=('-', '_'), get_first_key=True,
no_tag_node_value_mangle=True)
return if_firewall
def verify(if_firewall):
# bail out early - looks like removal from running config
if not if_firewall:
return None
for direction in ['in', 'out', 'local']:
if direction in if_firewall:
if 'name' in if_firewall[direction]:
name = if_firewall[direction]['name']
if 'name' not in if_firewall['firewall']:
raise ConfigError('Firewall name not configured')
if name not in if_firewall['firewall']['name']:
raise ConfigError(f'Invalid firewall name "{name}"')
if 'ipv6_name' in if_firewall[direction]:
name = if_firewall[direction]['ipv6_name']
if 'ipv6_name' not in if_firewall['firewall']:
raise ConfigError('Firewall ipv6-name not configured')
if name not in if_firewall['firewall']['ipv6_name']:
raise ConfigError(f'Invalid firewall ipv6-name "{name}"')
return None
def generate(if_firewall):
return None
def cleanup_rule(table, chain, prefix, ifname, new_name=None):
results = cmd(f'nft -a list chain {table} {chain}').split("\n")
retval = None
for line in results:
if f'{prefix}ifname "{ifname}"' in line:
if new_name and f'jump {new_name}' in line:
# new_name is used to clear rules for any previously referenced chains
# returns true when rule exists and doesn't need to be created
retval = True
continue
handle_search = re.search('handle (\d+)', line)
if handle_search:
run(f'nft delete rule {table} {chain} handle {handle_search[1]}')
return retval
def state_policy_handle(table, chain):
# Find any state-policy rule to ensure interface rules are only inserted afterwards
results = cmd(f'nft -a list chain {table} {chain}').split("\n")
for line in results:
if 'jump VYOS_STATE_POLICY' in line:
handle_search = re.search('handle (\d+)', line)
if handle_search:
return handle_search[1]
return None
def apply(if_firewall):
ifname = if_firewall['ifname']
for direction in ['in', 'out', 'local']:
chain = NFT_CHAINS[direction]
ipv6_chain = NFT6_CHAINS[direction]
if_prefix = 'i' if direction in ['in', 'local'] else 'o'
name = dict_search_args(if_firewall, direction, 'name')
if name:
rule_exists = cleanup_rule('ip filter', chain, if_prefix, ifname, f'{NAME_PREFIX}{name}')
if not rule_exists:
rule_action = 'insert'
rule_prefix = ''
handle = state_policy_handle('ip filter', chain)
if handle:
rule_action = 'add'
rule_prefix = f'position {handle}'
run(f'nft {rule_action} rule ip filter {chain} {rule_prefix} {if_prefix}ifname {ifname} counter jump {NAME_PREFIX}{name}')
else:
cleanup_rule('ip filter', chain, if_prefix, ifname)
ipv6_name = dict_search_args(if_firewall, direction, 'ipv6_name')
if ipv6_name:
rule_exists = cleanup_rule('ip6 filter', ipv6_chain, if_prefix, ifname, f'{NAME6_PREFIX}{ipv6_name}')
if not rule_exists:
rule_action = 'insert'
rule_prefix = ''
handle = state_policy_handle('ip6 filter', ipv6_chain)
if handle:
rule_action = 'add'
rule_prefix = f'position {handle}'
run(f'nft {rule_action} rule ip6 filter {ipv6_chain} {rule_prefix} {if_prefix}ifname {ifname} counter jump {NAME6_PREFIX}{ipv6_name}')
else:
cleanup_rule('ip6 filter', ipv6_chain, if_prefix, ifname)
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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