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zone_policy.py
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zone_policy.py
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#!/usr/bin/env python3
#
# Copyright (C) 2021-2022 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.config import Config
from vyos.configdict import dict_merge
from vyos.template import render
from vyos.util import cmd
from vyos.util import dict_search_args
from vyos.util import run
from vyos.xml import defaults
from vyos import ConfigError
from vyos import airbag
airbag.enable()
nftables_conf = '/run/nftables_zone.conf'
def get_config(config=None):
if config:
conf = config
else:
conf = Config()
base = ['zone-policy']
zone_policy = conf.get_config_dict(base, key_mangling=('-', '_'),
get_first_key=True,
no_tag_node_value_mangle=True)
zone_policy['firewall'] = conf.get_config_dict(['firewall'],
key_mangling=('-', '_'),
get_first_key=True,
no_tag_node_value_mangle=True)
if 'zone' in zone_policy:
# We have gathered the dict representation of the CLI, but there are default
# options which we need to update into the dictionary retrived.
default_values = defaults(base + ['zone'])
for zone in zone_policy['zone']:
zone_policy['zone'][zone] = dict_merge(default_values,
zone_policy['zone'][zone])
return zone_policy
def verify(zone_policy):
# bail out early - looks like removal from running config
if not zone_policy:
return None
local_zone = False
interfaces = []
if 'zone' in zone_policy:
for zone, zone_conf in zone_policy['zone'].items():
if 'local_zone' not in zone_conf and 'interface' not in zone_conf:
raise ConfigError(f'Zone "{zone}" has no interfaces and is not the local zone')
if 'local_zone' in zone_conf:
if local_zone:
raise ConfigError('There cannot be multiple local zones')
if 'interface' in zone_conf:
raise ConfigError('Local zone cannot have interfaces assigned')
if 'intra_zone_filtering' in zone_conf:
raise ConfigError('Local zone cannot use intra-zone-filtering')
local_zone = True
if 'interface' in zone_conf:
found_duplicates = [intf for intf in zone_conf['interface'] if intf in interfaces]
if found_duplicates:
raise ConfigError(f'Interfaces cannot be assigned to multiple zones')
interfaces += zone_conf['interface']
if 'intra_zone_filtering' in zone_conf:
intra_zone = zone_conf['intra_zone_filtering']
if len(intra_zone) > 1:
raise ConfigError('Only one intra-zone-filtering action must be specified')
if 'firewall' in intra_zone:
v4_name = dict_search_args(intra_zone, 'firewall', 'name')
if v4_name and not dict_search_args(zone_policy, 'firewall', 'name', v4_name):
raise ConfigError(f'Firewall name "{v4_name}" does not exist')
v6_name = dict_search_args(intra_zone, 'firewall', 'ipv6-name')
if v6_name and not dict_search_args(zone_policy, 'firewall', 'ipv6-name', v6_name):
raise ConfigError(f'Firewall ipv6-name "{v6_name}" does not exist')
if not v4_name and not v6_name:
raise ConfigError('No firewall names specified for intra-zone-filtering')
if 'from' in zone_conf:
for from_zone, from_conf in zone_conf['from'].items():
if from_zone not in zone_policy['zone']:
raise ConfigError(f'Zone "{zone}" refers to a non-existent or deleted zone "{from_zone}"')
v4_name = dict_search_args(from_conf, 'firewall', 'name')
if v4_name:
if 'name' not in zone_policy['firewall']:
raise ConfigError(f'Firewall name "{v4_name}" does not exist')
if not dict_search_args(zone_policy, 'firewall', 'name', v4_name):
raise ConfigError(f'Firewall name "{v4_name}" does not exist')
v6_name = dict_search_args(from_conf, 'firewall', 'v6_name')
if v6_name:
if 'ipv6_name' not in zone_policy['firewall']:
raise ConfigError(f'Firewall ipv6-name "{v6_name}" does not exist')
if not dict_search_args(zone_policy, 'firewall', 'ipv6_name', v6_name):
raise ConfigError(f'Firewall ipv6-name "{v6_name}" does not exist')
return None
def has_ipv4_fw(zone_conf):
if 'from' not in zone_conf:
return False
zone_from = zone_conf['from']
return any([True for fz in zone_from if dict_search_args(zone_from, fz, 'firewall', 'name')])
def has_ipv6_fw(zone_conf):
if 'from' not in zone_conf:
return False
zone_from = zone_conf['from']
return any([True for fz in zone_from if dict_search_args(zone_from, fz, 'firewall', 'ipv6_name')])
def get_local_from(zone_policy, local_zone_name):
# Get all zone firewall names from the local zone
out = {}
for zone, zone_conf in zone_policy['zone'].items():
if zone == local_zone_name:
continue
if 'from' not in zone_conf:
continue
if local_zone_name in zone_conf['from']:
out[zone] = zone_conf['from'][local_zone_name]
return out
def cleanup_commands():
commands = []
for table in ['ip filter', 'ip6 filter']:
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 'rule' in item:
chain = item['rule']['chain']
handle = item['rule']['handle']
if 'expr' not in item['rule']:
continue
for expr in item['rule']['expr']:
target = dict_search_args(expr, 'jump', 'target')
if not target:
continue
if target.startswith("VZONE") or target.startswith("VYOS_STATE_POLICY"):
commands.append(f'delete rule {table} {chain} handle {handle}')
for item in obj['nftables']:
if 'chain' in item:
if item['chain']['name'].startswith("VZONE"):
chain = item['chain']['name']
commands.append(f'delete chain {table} {chain}')
return commands
def generate(zone_policy):
data = zone_policy or {}
if os.path.exists(nftables_conf): # Check to see if we've run before
data['cleanup_commands'] = cleanup_commands()
if 'zone' in data:
for zone, zone_conf in data['zone'].items():
zone_conf['ipv4'] = has_ipv4_fw(zone_conf)
zone_conf['ipv6'] = has_ipv6_fw(zone_conf)
if 'local_zone' in zone_conf:
zone_conf['from_local'] = get_local_from(data, zone)
render(nftables_conf, 'zone_policy/nftables.tmpl', data)
return None
def apply(zone_policy):
install_result = run(f'nft -f {nftables_conf}')
if install_result != 0:
raise ConfigError('Failed to apply zone-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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