diff options
Diffstat (limited to 'src/conf_mode/policy.py')
| -rwxr-xr-x | src/conf_mode/policy.py | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/src/conf_mode/policy.py b/src/conf_mode/policy.py new file mode 100755 index 000000000..fb732dd81 --- /dev/null +++ b/src/conf_mode/policy.py @@ -0,0 +1,225 @@ +#!/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/>. + +from sys import exit + +from vyos.config import Config +from vyos.configdict import dict_merge +from vyos.template import render_to_string +from vyos.util import dict_search +from vyos import ConfigError +from vyos import frr +from vyos import airbag +airbag.enable() + +def routing_policy_find(key, dictionary): + # Recursively traverse a dictionary and extract the value assigned to + # a given key as generator object. This is made for routing policies, + # thus also import/export is checked + for k, v in dictionary.items(): + if k == key: + if isinstance(v, dict): + for a, b in v.items(): + if a in ['import', 'export']: + yield b + else: + yield v + elif isinstance(v, dict): + for result in routing_policy_find(key, v): + yield result + elif isinstance(v, list): + for d in v: + if isinstance(d, dict): + for result in routing_policy_find(key, d): + yield result + +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) + + # We also need some additional information from the config, prefix-lists + # and route-maps for instance. They will be used in verify(). + # + # XXX: one MUST always call this without the key_mangling() option! See + # vyos.configverify.verify_common_route_maps() for more information. + tmp = conf.get_config_dict(['protocols'], key_mangling=('-', '_'), + no_tag_node_value_mangle=True) + # Merge policy dict into "regular" config dict + policy = dict_merge(tmp, policy) + return policy + +def verify(policy): + if not policy: + return None + + for policy_type in ['access_list', 'access_list6', 'as_path_list', + 'community_list', 'extcommunity_list', 'large_community_list', + 'prefix_list', 'prefix_list6', 'route_map']: + # Bail out early and continue with next policy type + if policy_type not in policy: + continue + + # instance can be an ACL name/number, prefix-list name or route-map name + for instance, instance_config in policy[policy_type].items(): + # If no rule was found within the instance ... sad, but we can leave + # early as nothing needs to be verified + if 'rule' not in instance_config: + continue + + # human readable instance name (hypen instead of underscore) + policy_hr = policy_type.replace('_', '-') + for rule, rule_config in instance_config['rule'].items(): + mandatory_error = f'must be specified for "{policy_hr} {instance} rule {rule}"!' + if 'action' not in rule_config: + raise ConfigError(f'Action {mandatory_error}') + + if policy_type == 'access_list': + if 'source' not in rule_config: + raise ConfigError(f'A source {mandatory_error}') + + if int(instance) in range(100, 200) or int(instance) in range(2000, 2700): + if 'destination' not in rule_config: + raise ConfigError(f'A destination {mandatory_error}') + + if policy_type == 'access_list6': + if 'source' not in rule_config: + raise ConfigError(f'A source {mandatory_error}') + + if policy_type in ['as_path_list', 'community_list', 'extcommunity_list', + 'large_community_list']: + if 'regex' not in rule_config: + raise ConfigError(f'A regex {mandatory_error}') + + if policy_type in ['prefix_list', 'prefix_list6']: + if 'prefix' not in rule_config: + raise ConfigError(f'A prefix {mandatory_error}') + + + # route-maps tend to be a bit more complex so they get their own verify() section + if 'route_map' in policy: + for route_map, route_map_config in policy['route_map'].items(): + if 'rule' not in route_map_config: + continue + + for rule, rule_config in route_map_config['rule'].items(): + # Specified community-list must exist + tmp = dict_search('match.community.community_list', rule_config) + if tmp and tmp not in policy.get('community_list', []): + raise ConfigError(f'community-list {tmp} does not exist!') + + # Specified extended community-list must exist + tmp = dict_search('match.extcommunity', rule_config) + if tmp and tmp not in policy.get('extcommunity_list', []): + raise ConfigError(f'extcommunity-list {tmp} does not exist!') + + # Specified large-community-list must exist + tmp = dict_search('match.large_community.large_community_list', rule_config) + if tmp and tmp not in policy.get('large_community_list', []): + raise ConfigError(f'large-community-list {tmp} does not exist!') + + # Specified prefix-list must exist + tmp = dict_search('match.ip.address.prefix_list', rule_config) + if tmp and tmp not in policy.get('prefix_list', []): + raise ConfigError(f'prefix-list {tmp} does not exist!') + + # Specified prefix-list must exist + tmp = dict_search('match.ipv6.address.prefix_list', rule_config) + if tmp and tmp not in policy.get('prefix_list6', []): + raise ConfigError(f'prefix-list6 {tmp} does not exist!') + + # When routing protocols are active some use prefix-lists, route-maps etc. + # to apply the systems routing policy to the learned or redistributed routes. + # When the "routing policy" changes and policies, route-maps etc. are deleted, + # it is our responsibility to verify that the policy can not be deleted if it + # is used by any routing protocol + if 'protocols' in policy: + for policy_type in ['access_list', 'access_list6', 'as_path_list', 'community_list', + 'extcommunity_list', 'large_community_list', 'prefix_list', 'route_map']: + if policy_type in policy: + for policy_name in list(set(routing_policy_find(policy_type, policy['protocols']))): + found = False + if policy_name in policy[policy_type]: + found = True + # BGP uses prefix-list for selecting both an IPv4 or IPv6 AFI related + # list - we need to go the extra mile here and check both prefix-lists + if policy_type == 'prefix_list' and 'prefix_list6' in policy and policy_name in policy['prefix_list6']: + found = True + if not found: + tmp = policy_type.replace('_','-') + raise ConfigError(f'Can not delete {tmp} "{name}", still in use!') + + return None + +def generate(policy): + if not policy: + policy['new_frr_config'] = '' + return None + + policy['new_frr_config'] = render_to_string('frr/policy.frr.tmpl', policy) + return None + +def apply(policy): + bgp_daemon = 'bgpd' + zebra_daemon = 'zebra' + + # Save original configuration prior to starting any commit actions + frr_cfg = frr.FRRConfig() + + # The route-map used for the FIB (zebra) is part of the zebra daemon + frr_cfg.load_configuration(bgp_daemon) + frr_cfg.modify_section(r'^bgp as-path access-list .*') + frr_cfg.modify_section(r'^bgp community-list .*') + frr_cfg.modify_section(r'^bgp extcommunity-list .*') + frr_cfg.modify_section(r'^bgp large-community-list .*') + frr_cfg.add_before('^line vty', policy['new_frr_config']) + frr_cfg.commit_configuration(bgp_daemon) + + # The route-map used for the FIB (zebra) is part of the zebra daemon + frr_cfg.load_configuration(zebra_daemon) + frr_cfg.modify_section(r'^access-list .*') + frr_cfg.modify_section(r'^ipv6 access-list .*') + frr_cfg.modify_section(r'^ip prefix-list .*') + frr_cfg.modify_section(r'^ipv6 prefix-list .*') + frr_cfg.modify_section(r'^route-map .*') + frr_cfg.add_before('^line vty', policy['new_frr_config']) + frr_cfg.commit_configuration(zebra_daemon) + + # If FRR config is blank, rerun the blank commit x times due to frr-reload + # behavior/bug not properly clearing out on one commit. + if policy['new_frr_config'] == '': + for a in range(5): + frr_cfg.commit_configuration(zebra_daemon) + + # Save configuration to /run/frr/config/frr.conf + frr.save_configuration() + + return None + +if __name__ == '__main__': + try: + c = get_config() + verify(c) + generate(c) + apply(c) + except ConfigError as e: + print(e) + exit(1) |