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path: root/src/conf_mode/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.configdiff import get_config_diff
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()

firewall_conf_script = '/usr/libexec/vyos/conf_mode/firewall.py'
nftables_conf = '/run/nftables_zone.conf'
nftables6_conf = '/run/nftables_zone6.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)

    diff = get_config_diff(conf)
    zone_policy['firewall_changed'] = diff.is_node_changed(['firewall'])

    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 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(from_conf, 'firewall', 'v6_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')

    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 generate(zone_policy):
    data = zone_policy or {}

    if not os.path.exists(nftables_conf):
        data['first_install'] = True

    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.j2', data)
    render(nftables6_conf, 'zone_policy/nftables6.j2', data)
    return None

def update_firewall():
    # Update firewall to refresh nftables
    tmp = run(firewall_conf_script)
    if tmp > 0:
        Warning('Failed to update firewall configuration!')

def apply(zone_policy):
    # If firewall will not update in this commit, we need to call the conf script
    if not zone_policy['firewall_changed']:
        update_firewall()

    return None

if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print(e)
        exit(1)