diff options
Diffstat (limited to 'src')
| -rwxr-xr-x | src/conf_mode/nat_cgnat.py | 288 |
1 files changed, 288 insertions, 0 deletions
diff --git a/src/conf_mode/nat_cgnat.py b/src/conf_mode/nat_cgnat.py new file mode 100755 index 000000000..f41d66c66 --- /dev/null +++ b/src/conf_mode/nat_cgnat.py @@ -0,0 +1,288 @@ +#!/usr/bin/env python3 +# +# Copyright (C) 2024 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 ipaddress +import jmespath +import os + +from sys import exit + +from vyos.config import Config +from vyos.template import render +from vyos.utils.process import cmd +from vyos.utils.process import run +from vyos import ConfigError +from vyos import airbag + +airbag.enable() + + +nftables_cgnat_config = '/run/nftables-cgnat.nft' + + +class IPOperations: + def __init__(self, ip_prefix: str): + self.ip_prefix = ip_prefix + self.ip_network = ipaddress.ip_network(ip_prefix) if '/' in ip_prefix else None + + def get_ips_count(self) -> int: + """Returns the number of IPs in a prefix or range. + + Example: + % ip = IPOperations('192.0.2.0/30') + % ip.get_ips_count() + 4 + % ip = IPOperations('192.0.2.0-192.0.2.2') + % ip.get_ips_count() + 3 + """ + if '-' in self.ip_prefix: + start_ip, end_ip = self.ip_prefix.split('-') + start_ip = ipaddress.ip_address(start_ip) + end_ip = ipaddress.ip_address(end_ip) + return int(end_ip) - int(start_ip) + 1 + elif '/31' in self.ip_prefix: + return 2 + elif '/32' in self.ip_prefix: + return 1 + else: + return sum( + 1 + for _ in [self.ip_network.network_address] + + list(self.ip_network.hosts()) + + [self.ip_network.broadcast_address] + ) + + def convert_prefix_to_list_ips(self) -> list: + """Converts a prefix or IP range to a list of IPs including the network and broadcast addresses. + + Example: + % ip = IPOperations('192.0.2.0/30') + % ip.convert_prefix_to_list_ips() + ['192.0.2.0', '192.0.2.1', '192.0.2.2', '192.0.2.3'] + % + % ip = IPOperations('192.0.0.1-192.0.2.5') + % ip.convert_prefix_to_list_ips() + ['192.0.2.1', '192.0.2.2', '192.0.2.3', '192.0.2.4', '192.0.2.5'] + """ + if '-' in self.ip_prefix: + start_ip, end_ip = self.ip_prefix.split('-') + start_ip = ipaddress.ip_address(start_ip) + end_ip = ipaddress.ip_address(end_ip) + return [ + str(ipaddress.ip_address(ip)) + for ip in range(int(start_ip), int(end_ip) + 1) + ] + elif '/31' in self.ip_prefix: + return [ + str(ip) + for ip in [ + self.ip_network.network_address, + self.ip_network.broadcast_address, + ] + ] + elif '/32' in self.ip_prefix: + return [str(self.ip_network.network_address)] + else: + return [ + str(ip) + for ip in [self.ip_network.network_address] + + list(self.ip_network.hosts()) + + [self.ip_network.broadcast_address] + ] + + +def generate_port_rules( + external_hosts: list, + internal_hosts: list, + port_count: int, + global_port_range: str = '1024-65535', +) -> list: + """Generates list of nftables rules for the batch file.""" + rules = [] + proto_map_elements = [] + other_map_elements = [] + start_port, end_port = map(int, global_port_range.split('-')) + total_possible_ports = (end_port - start_port) + 1 + + # Calculate the required number of ports per host + required_ports_per_host = port_count + + # Check if there are enough external addresses for all internal hosts + if required_ports_per_host * len(internal_hosts) > total_possible_ports * len( + external_hosts + ): + raise ConfigError("Not enough ports available for the specified parameters!") + + current_port = start_port + current_external_index = 0 + + for internal_host in internal_hosts: + external_host = external_hosts[current_external_index] + next_end_port = current_port + required_ports_per_host - 1 + + # If the port range exceeds the end_port, move to the next external host + while next_end_port > end_port: + current_external_index = (current_external_index + 1) % len(external_hosts) + external_host = external_hosts[current_external_index] + current_port = start_port + next_end_port = current_port + required_ports_per_host - 1 + + # Ensure the same port is not assigned to the same external host + if any( + rule.endswith(f'{external_host}:{current_port}-{next_end_port}') + for rule in rules + ): + raise ConfigError("Not enough ports available for the specified parameters") + + proto_map_elements.append( + f'{internal_host} : {external_host} . {current_port}-{next_end_port}' + ) + other_map_elements.append(f'{internal_host} : {external_host}') + + current_port = next_end_port + 1 + if current_port > end_port: + current_port = start_port + current_external_index += 1 # Move to the next external host + + return [proto_map_elements, other_map_elements] + + +def get_config(config=None): + if config: + conf = config + else: + conf = Config() + + base = ['nat', 'cgnat'] + config = conf.get_config_dict( + base, + get_first_key=True, + key_mangling=('-', '_'), + no_tag_node_value_mangle=True, + with_recursive_defaults=True, + ) + + return config + + +def verify(config): + # bail out early - looks like removal from running config + if not config: + return None + + if 'pool' not in config: + raise ConfigError(f'Pool must be defined!') + if 'rule' not in config: + raise ConfigError(f'Rule must be defined!') + + # As PoC allow only one rule for CGNAT translations + # one internal pool and one external pool + if len(config['rule']) > 1: + raise ConfigError(f'Only one rule is allowed for translations!') + + for pool in ('external', 'internal'): + if pool not in config['pool']: + raise ConfigError(f'{pool} pool must be defined!') + for pool_name, pool_config in config['pool'][pool].items(): + if 'range' not in pool_config: + raise ConfigError( + f'Range for "{pool} pool {pool_name}" must be defined!' + ) + + for rule, rule_config in config['rule'].items(): + if 'source' not in rule_config: + raise ConfigError(f'Rule "{rule}" source pool must be defined!') + if 'pool' not in rule_config['source']: + raise ConfigError(f'Rule "{rule}" source pool must be defined!') + + if 'translation' not in rule_config: + raise ConfigError(f'Rule "{rule}" translation pool must be defined!') + + +def generate(config): + if not config: + return None + # first external pool as we allow only one as PoC + ext_pool_name = jmespath.search("rule.*.translation | [0]", config).get('pool') + int_pool_name = jmespath.search("rule.*.source | [0]", config).get('pool') + ext_query = f"pool.external.{ext_pool_name}.range | keys(@)" + int_query = f"pool.internal.{int_pool_name}.range" + external_ranges = jmespath.search(ext_query, config) + internal_ranges = [jmespath.search(int_query, config)] + + external_list_count = [] + external_list_hosts = [] + internal_list_count = [] + internal_list_hosts = [] + for ext_range in external_ranges: + # External hosts count + e_count = IPOperations(ext_range).get_ips_count() + external_list_count.append(e_count) + # External hosts list + e_hosts = IPOperations(ext_range).convert_prefix_to_list_ips() + external_list_hosts.extend(e_hosts) + for int_range in internal_ranges: + # Internal hosts count + i_count = IPOperations(int_range).get_ips_count() + internal_list_count.append(i_count) + # Internal hosts list + i_hosts = IPOperations(int_range).convert_prefix_to_list_ips() + internal_list_hosts.extend(i_hosts) + + external_host_count = sum(external_list_count) + internal_host_count = sum(internal_list_count) + ports_per_user = int( + jmespath.search(f'pool.external.{ext_pool_name}.per_user_limit.port', config) + ) + external_port_range: str = jmespath.search( + f'pool.external.{ext_pool_name}.external_port_range', config + ) + + proto_maps, other_maps = generate_port_rules( + external_list_hosts, internal_list_hosts, ports_per_user, external_port_range + ) + + config['proto_map_elements'] = ', '.join(proto_maps) + config['other_map_elements'] = ', '.join(other_maps) + + render(nftables_cgnat_config, 'firewall/nftables-cgnat.j2', config) + + # dry-run newly generated configuration + tmp = run(f'nft --check --file {nftables_cgnat_config}') + if tmp > 0: + raise ConfigError('Configuration file errors encountered!') + + +def apply(config): + if not config: + # Cleanup cgnat + cmd('nft delete table ip cgnat') + if os.path.isfile(nftables_cgnat_config): + os.unlink(nftables_cgnat_config) + return None + cmd(f'nft --file {nftables_cgnat_config}') + + +if __name__ == '__main__': + try: + c = get_config() + verify(c) + generate(c) + apply(c) + except ConfigError as e: + print(e) + exit(1) |