T5474: establish common file name pattern for XML conf mode commands

We will use _ as CLI level divider. The XML definition filename and also
the Python helper should match the CLI node.

Example:
set interfaces ethernet -> interfaces_ethernet.xml.in
set interfaces bond -> interfaces_bond.xml.in
set service dhcp-server -> service_dhcp-server-xml.in

(cherry picked from commit 4ef110fd2c501b718344c72d495ad7e16d2bd465)

1 files changed, 731 insertions, 0 deletions

diff --git a/src/conf_mode/interfaces_openvpn.py b/src/conf_mode/interfaces_openvpn.py
new file mode 100755
index 000000000..85905fd9a
--- /dev/null
+++ b/src/conf_mode/interfaces_openvpn.py
@@ -0,0 +1,731 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019-2023 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
+import tempfile
+
+from cryptography.hazmat.primitives.asymmetric import ec
+from glob import glob
+from sys import exit
+from ipaddress import IPv4Address
+from ipaddress import IPv4Network
+from ipaddress import IPv6Address
+from ipaddress import IPv6Network
+from ipaddress import summarize_address_range
+from netifaces import interfaces
+from secrets import SystemRandom
+from shutil import rmtree
+
+from vyos.base import DeprecationWarning
+from vyos.config import Config
+from vyos.configdict import get_interface_dict
+from vyos.configdict import is_node_changed
+from vyos.configverify import verify_vrf
+from vyos.configverify import verify_bridge_delete
+from vyos.configverify import verify_mirror_redirect
+from vyos.configverify import verify_bond_bridge_member
+from vyos.ifconfig import VTunIf
+from vyos.pki import load_dh_parameters
+from vyos.pki import load_private_key
+from vyos.pki import sort_ca_chain
+from vyos.pki import verify_ca_chain
+from vyos.pki import wrap_certificate
+from vyos.pki import wrap_crl
+from vyos.pki import wrap_dh_parameters
+from vyos.pki import wrap_openvpn_key
+from vyos.pki import wrap_private_key
+from vyos.template import render
+from vyos.template import is_ipv4
+from vyos.template import is_ipv6
+from vyos.utils.dict import dict_search
+from vyos.utils.dict import dict_search_args
+from vyos.utils.list import is_list_equal
+from vyos.utils.file import makedir
+from vyos.utils.file import read_file
+from vyos.utils.file import write_file
+from vyos.utils.kernel import check_kmod
+from vyos.utils.kernel import unload_kmod
+from vyos.utils.process import call
+from vyos.utils.permission import chown
+from vyos.utils.process import cmd
+from vyos.utils.network import is_addr_assigned
+
+from vyos import ConfigError
+from vyos import airbag
+airbag.enable()
+
+user = 'openvpn'
+group = 'openvpn'
+
+cfg_dir = '/run/openvpn'
+cfg_file = '/run/openvpn/{ifname}.conf'
+otp_path = '/config/auth/openvpn'
+otp_file = '/config/auth/openvpn/{ifname}-otp-secrets'
+secret_chars = list('ABCDEFGHIJKLMNOPQRSTUVWXYZ234567')
+service_file = '/run/systemd/system/openvpn@{ifname}.service.d/20-override.conf'
+
+def get_config(config=None):
+    """
+    Retrive CLI config as dictionary. Dictionary can never be empty, as at least the
+    interface name will be added or a deleted flag
+    """
+    if config:
+        conf = config
+    else:
+        conf = Config()
+    base = ['interfaces', 'openvpn']
+
+    ifname, openvpn = get_interface_dict(conf, base)
+    openvpn['auth_user_pass_file'] = '/run/openvpn/{ifname}.pw'.format(**openvpn)
+
+    if 'deleted' in openvpn:
+        return openvpn
+
+    openvpn['pki'] = conf.get_config_dict(['pki'], key_mangling=('-', '_'),
+                                        get_first_key=True,
+                                        no_tag_node_value_mangle=True)
+
+    if is_node_changed(conf, base + [ifname, 'openvpn-option']):
+        openvpn.update({'restart_required': {}})
+    if is_node_changed(conf, base + [ifname, 'enable-dco']):
+        openvpn.update({'restart_required': {}})
+
+    # We have to get the dict using 'get_config_dict' instead of 'get_interface_dict'
+    # as 'get_interface_dict' merges the defaults in, so we can not check for defaults in there.
+    tmp = conf.get_config_dict(base + [openvpn['ifname']], get_first_key=True)
+
+    # We have to cleanup the config dict, as default values could enable features
+    # which are not explicitly enabled on the CLI. Example: server mfa totp
+    # originate comes with defaults, which will enable the
+    # totp plugin, even when not set via CLI so we
+    # need to check this first and drop those keys
+    if dict_search('server.mfa.totp', tmp) == None:
+        del openvpn['server']['mfa']
+
+    # OpenVPN Data-Channel-Offload (DCO) is a Kernel module. If loaded it applies to all
+    # OpenVPN interfaces. Check if DCO is used by any other interface instance.
+    tmp = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
+    for interface, interface_config in tmp.items():
+        # If one interface has DCO configured, enable it. No need to further check
+        # all other OpenVPN interfaces. We must use a dedicated key to indicate
+        # the Kernel module must be loaded or not. The per interface "offload.dco"
+        # key is required per OpenVPN interface instance.
+        if dict_search('offload.dco', interface_config) != None:
+            openvpn['module_load_dco'] = {}
+            break
+
+    return openvpn
+
+def is_ec_private_key(pki, cert_name):
+    if not pki or 'certificate' not in pki:
+        return False
+    if cert_name not in pki['certificate']:
+        return False
+
+    pki_cert = pki['certificate'][cert_name]
+    if 'private' not in pki_cert or 'key' not in pki_cert['private']:
+        return False
+
+    key = load_private_key(pki_cert['private']['key'])
+    return isinstance(key, ec.EllipticCurvePrivateKey)
+
+def verify_pki(openvpn):
+    pki = openvpn['pki']
+    interface = openvpn['ifname']
+    mode = openvpn['mode']
+    shared_secret_key = dict_search_args(openvpn, 'shared_secret_key')
+    tls = dict_search_args(openvpn, 'tls')
+
+    if not bool(shared_secret_key) ^ bool(tls): #  xor check if only one is set
+        raise ConfigError('Must specify only one of "shared-secret-key" and "tls"')
+
+    if mode in ['server', 'client'] and not tls:
+        raise ConfigError('Must specify "tls" for server and client modes')
+
+    if not pki:
+        raise ConfigError('PKI is not configured')
+
+    if shared_secret_key:
+        if not dict_search_args(pki, 'openvpn', 'shared_secret'):
+            raise ConfigError('There are no openvpn shared-secrets in PKI configuration')
+
+        if shared_secret_key not in pki['openvpn']['shared_secret']:
+            raise ConfigError(f'Invalid shared-secret on openvpn interface {interface}')
+
+        # If PSK settings are correct, warn about its deprecation
+        DeprecationWarning("OpenVPN shared-secret support will be removed in future VyOS versions.\n\
+        Please migrate your site-to-site tunnels to TLS.\n\
+        You can use self-signed certificates with peer fingerprint verification, consult the documentation for details.")
+
+    if tls:
+        if (mode in ['server', 'client']) and ('ca_certificate' not in tls):
+            raise ConfigError(f'Must specify "tls ca-certificate" on openvpn interface {interface},\
+              it is required in server and client modes')
+        else:
+            if ('ca_certificate' not in tls) and ('peer_fingerprint' not in tls):
+                raise ConfigError('Either "tls ca-certificate" or "tls peer-fingerprint" is required\
+                  on openvpn interface {interface} in site-to-site mode')
+
+        if 'ca_certificate' in tls:
+            for ca_name in tls['ca_certificate']:
+                if ca_name not in pki['ca']:
+                    raise ConfigError(f'Invalid CA certificate on openvpn interface {interface}')
+
+            if len(tls['ca_certificate']) > 1:
+                sorted_chain = sort_ca_chain(tls['ca_certificate'], pki['ca'])
+                if not verify_ca_chain(sorted_chain, pki['ca']):
+                    raise ConfigError(f'CA certificates are not a valid chain')
+
+        if mode != 'client' and 'auth_key' not in tls:
+            if 'certificate' not in tls:
+                raise ConfigError(f'Missing "tls certificate" on openvpn interface {interface}')
+
+        if 'certificate' in tls:
+            if tls['certificate'] not in pki['certificate']:
+                raise ConfigError(f'Invalid certificate on openvpn interface {interface}')
+
+            if dict_search_args(pki, 'certificate', tls['certificate'], 'private', 'password_protected') is not None:
+                raise ConfigError(f'Cannot use encrypted private key on openvpn interface {interface}')
+
+        if 'dh_params' in tls:
+            pki_dh = pki['dh'][tls['dh_params']]
+            dh_params = load_dh_parameters(pki_dh['parameters'])
+            dh_numbers = dh_params.parameter_numbers()
+            dh_bits = dh_numbers.p.bit_length()
+
+            if dh_bits < 2048:
+                raise ConfigError(f'Minimum DH key-size is 2048 bits')
+
+
+        if 'auth_key' in tls or 'crypt_key' in tls:
+            if not dict_search_args(pki, 'openvpn', 'shared_secret'):
+                raise ConfigError('There are no openvpn shared-secrets in PKI configuration')
+
+        if 'auth_key' in tls:
+            if tls['auth_key'] not in pki['openvpn']['shared_secret']:
+                raise ConfigError(f'Invalid auth-key on openvpn interface {interface}')
+
+        if 'crypt_key' in tls:
+            if tls['crypt_key'] not in pki['openvpn']['shared_secret']:
+                raise ConfigError(f'Invalid crypt-key on openvpn interface {interface}')
+
+def verify(openvpn):
+    if 'deleted' in openvpn:
+        # remove totp secrets file if totp is not configured
+        if os.path.isfile(otp_file.format(**openvpn)):
+            os.remove(otp_file.format(**openvpn))
+
+        verify_bridge_delete(openvpn)
+        return None
+
+    if 'mode' not in openvpn:
+        raise ConfigError('Must specify OpenVPN operation mode!')
+
+    #
+    # OpenVPN client mode - VERIFY
+    #
+    if openvpn['mode'] == 'client':
+        if 'local_port' in openvpn:
+            raise ConfigError('Cannot specify "local-port" in client mode')
+
+        if 'local_host' in openvpn:
+            raise ConfigError('Cannot specify "local-host" in client mode')
+
+        if 'remote_host' not in openvpn:
+            raise ConfigError('Must specify "remote-host" in client mode')
+
+        if openvpn['protocol'] == 'tcp-passive':
+            raise ConfigError('Protocol "tcp-passive" is not valid in client mode')
+
+        if dict_search('tls.dh_params', openvpn):
+            raise ConfigError('Cannot specify "tls dh-params" in client mode')
+
+    #
+    # OpenVPN site-to-site - VERIFY
+    #
+    elif openvpn['mode'] == 'site-to-site':
+        if 'local_address' not in openvpn and 'is_bridge_member' not in openvpn:
+            raise ConfigError('Must specify "local-address" or add interface to bridge')
+
+        if 'local_address' in openvpn:
+            if len([addr for addr in openvpn['local_address'] if is_ipv4(addr)]) > 1:
+                raise ConfigError('Only one IPv4 local-address can be specified')
+
+            if len([addr for addr in openvpn['local_address'] if is_ipv6(addr)]) > 1:
+                raise ConfigError('Only one IPv6 local-address can be specified')
+
+        if openvpn['device_type'] == 'tun':
+            if 'remote_address' not in openvpn:
+                raise ConfigError('Must specify "remote-address"')
+
+        if 'remote_address' in openvpn:
+            if len([addr for addr in openvpn['remote_address'] if is_ipv4(addr)]) > 1:
+                raise ConfigError('Only one IPv4 remote-address can be specified')
+
+            if len([addr for addr in openvpn['remote_address'] if is_ipv6(addr)]) > 1:
+                raise ConfigError('Only one IPv6 remote-address can be specified')
+
+            if not 'local_address' in openvpn:
+                raise ConfigError('"remote-address" requires "local-address"')
+
+            v4loAddr = [addr for addr in openvpn['local_address'] if is_ipv4(addr)]
+            v4remAddr = [addr for addr in openvpn['remote_address'] if is_ipv4(addr)]
+            if v4loAddr and not v4remAddr:
+                raise ConfigError('IPv4 "local-address" requires IPv4 "remote-address"')
+            elif v4remAddr and not v4loAddr:
+                raise ConfigError('IPv4 "remote-address" requires IPv4 "local-address"')
+
+            v6remAddr = [addr for addr in openvpn['remote_address'] if is_ipv6(addr)]
+            v6loAddr = [addr for addr in openvpn['local_address'] if is_ipv6(addr)]
+            if v6loAddr and not v6remAddr:
+                raise ConfigError('IPv6 "local-address" requires IPv6 "remote-address"')
+            elif v6remAddr and not v6loAddr:
+                raise ConfigError('IPv6 "remote-address" requires IPv6 "local-address"')
+
+            if is_list_equal(v4loAddr, v4remAddr) or is_list_equal(v6loAddr, v6remAddr):
+                raise ConfigError('"local-address" and "remote-address" cannot be the same')
+
+            if dict_search('local_host', openvpn) in dict_search('local_address', openvpn):
+                raise ConfigError('"local-address" cannot be the same as "local-host"')
+
+            if dict_search('remote_host', openvpn) in dict_search('remote_address', openvpn):
+                raise ConfigError('"remote-address" and "remote-host" can not be the same')
+
+        if openvpn['device_type'] == 'tap' and 'local_address' in openvpn:
+            # we can only have one local_address, this is ensured above
+            v4addr = None
+            for laddr in openvpn['local_address']:
+                if is_ipv4(laddr):
+                    v4addr = laddr
+                    break
+
+            if v4addr in openvpn['local_address'] and 'subnet_mask' not in openvpn['local_address'][v4addr]:
+                raise ConfigError('Must specify IPv4 "subnet-mask" for local-address')
+
+        if dict_search('encryption.ncp_ciphers', openvpn):
+            raise ConfigError('NCP ciphers can only be used in client or server mode')
+
+    else:
+        # checks for client-server or site-to-site bridged
+        if 'local_address' in openvpn or 'remote_address' in openvpn:
+            raise ConfigError('Cannot specify "local-address" or "remote-address" ' \
+                              'in client/server or bridge mode')
+
+    #
+    # OpenVPN server mode - VERIFY
+    #
+    if openvpn['mode'] == 'server':
+        if openvpn['protocol'] == 'tcp-active':
+            raise ConfigError('Protocol "tcp-active" is not valid in server mode')
+
+        if dict_search('authentication.username', openvpn) or dict_search('authentication.password', openvpn):
+            raise ConfigError('Cannot specify "authentication" in server mode')
+
+        if 'remote_port' in openvpn:
+            raise ConfigError('Cannot specify "remote-port" in server mode')
+
+        if 'remote_host' in openvpn:
+            raise ConfigError('Cannot specify "remote-host" in server mode')
+
+        tmp = dict_search('server.subnet', openvpn)
+        if tmp:
+            v4_subnets = len([subnet for subnet in tmp if is_ipv4(subnet)])
+            v6_subnets = len([subnet for subnet in tmp if is_ipv6(subnet)])
+            if v4_subnets > 1:
+                raise ConfigError('Cannot specify more than 1 IPv4 server subnet')
+            if v6_subnets > 1:
+                raise ConfigError('Cannot specify more than 1 IPv6 server subnet')
+
+            if v6_subnets > 0 and v4_subnets == 0:
+                raise ConfigError('IPv6 server requires an IPv4 server subnet')
+
+            for subnet in tmp:
+                if is_ipv4(subnet):
+                    subnet = IPv4Network(subnet)
+
+                    if openvpn['device_type'] == 'tun' and subnet.prefixlen > 29:
+                        raise ConfigError('Server subnets smaller than /29 with device type "tun" are not supported')
+                    elif openvpn['device_type'] == 'tap' and subnet.prefixlen > 30:
+                        raise ConfigError('Server subnets smaller than /30 with device type "tap" are not supported')
+
+                    for client in (dict_search('client', openvpn) or []):
+                        if client['ip'] and not IPv4Address(client['ip'][0]) in subnet:
+                            raise ConfigError(f'Client "{client["name"]}" IP {client["ip"][0]} not in server subnet {subnet}')
+
+        else:
+            if 'is_bridge_member' not in openvpn:
+                raise ConfigError('Must specify "server subnet" or add interface to bridge in server mode')
+
+        if hasattr(dict_search('server.client', openvpn), '__iter__'):
+            for client_k, client_v in dict_search('server.client', openvpn).items():
+                if (client_v.get('ip') and len(client_v['ip']) > 1) or (client_v.get('ipv6_ip') and len(client_v['ipv6_ip']) > 1):
+                    raise ConfigError(f'Server client "{client_k}": cannot specify more than 1 IPv4 and 1 IPv6 IP')
+
+        if dict_search('server.client_ip_pool', openvpn):
+            if not (dict_search('server.client_ip_pool.start', openvpn) and dict_search('server.client_ip_pool.stop', openvpn)):
+                raise ConfigError('Server client-ip-pool requires both start and stop addresses')
+            else:
+                v4PoolStart = IPv4Address(dict_search('server.client_ip_pool.start', openvpn))
+                v4PoolStop = IPv4Address(dict_search('server.client_ip_pool.stop', openvpn))
+                if v4PoolStart > v4PoolStop:
+                    raise ConfigError(f'Server client-ip-pool start address {v4PoolStart} is larger than stop address {v4PoolStop}')
+
+                v4PoolSize = int(v4PoolStop) - int(v4PoolStart)
+                if v4PoolSize >= 65536:
+                    raise ConfigError(f'Server client-ip-pool is too large [{v4PoolStart} -> {v4PoolStop} = {v4PoolSize}], maximum is 65536 addresses.')
+
+                v4PoolNets = list(summarize_address_range(v4PoolStart, v4PoolStop))
+                for client in (dict_search('client', openvpn) or []):
+                    if client['ip']:
+                        for v4PoolNet in v4PoolNets:
+                            if IPv4Address(client['ip'][0]) in v4PoolNet:
+                                print(f'Warning: Client "{client["name"]}" IP {client["ip"][0]} is in server IP pool, it is not reserved for this client.')
+
+        for subnet in (dict_search('server.subnet', openvpn) or []):
+            if is_ipv6(subnet):
+                tmp = dict_search('client_ipv6_pool.base', openvpn)
+                if tmp:
+                    if not dict_search('server.client_ip_pool', openvpn):
+                        raise ConfigError('IPv6 server pool requires an IPv4 server pool')
+
+                    if int(tmp.split('/')[1]) >= 112:
+                        raise ConfigError('IPv6 server pool must be larger than /112')
+
+                    #
+                    # todo - weird logic
+                    #
+                    v6PoolStart = IPv6Address(tmp)
+                    v6PoolStop = IPv6Network((v6PoolStart, openvpn['server_ipv6_pool_prefixlen']), strict=False)[-1] # don't remove the parentheses, it's a 2-tuple
+                    v6PoolSize = int(v6PoolStop) - int(v6PoolStart) if int(openvpn['server_ipv6_pool_prefixlen']) > 96 else 65536
+                    if v6PoolSize < v4PoolSize:
+                        raise ConfigError(f'IPv6 server pool must be at least as large as the IPv4 pool (current sizes: IPv6={v6PoolSize} IPv4={v4PoolSize})')
+
+                    v6PoolNets = list(summarize_address_range(v6PoolStart, v6PoolStop))
+                    for client in (dict_search('client', openvpn) or []):
+                        if client['ipv6_ip']:
+                            for v6PoolNet in v6PoolNets:
+                                if IPv6Address(client['ipv6_ip'][0]) in v6PoolNet:
+                                    print(f'Warning: Client "{client["name"]}" IP {client["ipv6_ip"][0]} is in server IP pool, it is not reserved for this client.')
+
+        # add mfa users to the file the mfa plugin uses
+        if dict_search('server.mfa.totp', openvpn):
+            user_data = ''
+            if not os.path.isfile(otp_file.format(**openvpn)):
+                write_file(otp_file.format(**openvpn), user_data,
+                           user=user, group=group, mode=0o644)
+
+            ovpn_users = read_file(otp_file.format(**openvpn))
+            for client in (dict_search('server.client', openvpn) or []):
+                exists = None
+                for ovpn_user in ovpn_users.split('\n'):
+                    if re.search('^' + client + ' ', ovpn_user):
+                        user_data += f'{ovpn_user}\n'
+                        exists = 'true'
+
+                if not exists:
+                    random = SystemRandom()
+                    totp_secret = ''.join(random.choice(secret_chars) for _ in range(16))
+                    user_data += f'{client} otp totp:sha1:base32:{totp_secret}::xxx *\n'
+
+            write_file(otp_file.format(**openvpn), user_data,
+                           user=user, group=group, mode=0o644)
+
+    else:
+        # checks for both client and site-to-site go here
+        if dict_search('server.reject_unconfigured_clients', openvpn):
+            raise ConfigError('Option reject-unconfigured-clients only supported in server mode')
+
+        if 'replace_default_route' in openvpn and 'remote_host' not in openvpn:
+            raise ConfigError('Cannot set "replace-default-route" without "remote-host"')
+
+    #
+    # OpenVPN common verification section
+    # not depending on any operation mode
+    #
+
+    # verify specified IP address is present on any interface on this system
+    if 'local_host' in openvpn:
+        if not is_addr_assigned(openvpn['local_host']):
+            print('local-host IP address "{local_host}" not assigned' \
+                  ' to any interface'.format(**openvpn))
+
+    # TCP active
+    if openvpn['protocol'] == 'tcp-active':
+        if 'local_port' in openvpn:
+            raise ConfigError('Cannot specify "local-port" with "tcp-active"')
+
+        if 'remote_host' not in openvpn:
+            raise ConfigError('Must specify "remote-host" with "tcp-active"')
+
+    #
+    # TLS/encryption
+    #
+    if 'shared_secret_key' in openvpn:
+        if dict_search('encryption.cipher', openvpn) in ['aes128gcm', 'aes192gcm', 'aes256gcm']:
+            raise ConfigError('GCM encryption with shared-secret-key not supported')
+
+    if 'tls' in openvpn:
+        if {'auth_key', 'crypt_key'} <= set(openvpn['tls']):
+            raise ConfigError('TLS auth and crypt keys are mutually exclusive')
+
+        tmp = dict_search('tls.role', openvpn)
+        if tmp:
+            if openvpn['mode'] in ['client', 'server']:
+                if not dict_search('tls.auth_key', openvpn):
+                    raise ConfigError('Cannot specify "tls role" in client-server mode')
+
+            if tmp == 'active':
+                if openvpn['protocol'] == 'tcp-passive':
+                    raise ConfigError('Cannot specify "tcp-passive" when "tls role" is "active"')
+
+                if dict_search('tls.dh_params', openvpn):
+                    raise ConfigError('Cannot specify "tls dh-params" when "tls role" is "active"')
+
+            elif tmp == 'passive':
+                if openvpn['protocol'] == 'tcp-active':
+                    raise ConfigError('Cannot specify "tcp-active" when "tls role" is "passive"')
+
+        if 'certificate' in openvpn['tls'] and is_ec_private_key(openvpn['pki'], openvpn['tls']['certificate']):
+            if 'dh_params' in openvpn['tls']:
+                print('Warning: using dh-params and EC keys simultaneously will ' \
+                      'lead to DH ciphers being used instead of ECDH')
+
+    if dict_search('encryption.cipher', openvpn) == 'none':
+        print('Warning: "encryption none" was specified!')
+        print('No encryption will be performed and data is transmitted in ' \
+              'plain text over the network!')
+
+    verify_pki(openvpn)
+
+    #
+    # Auth user/pass
+    #
+    if (dict_search('authentication.username', openvpn) and not
+        dict_search('authentication.password', openvpn)):
+            raise ConfigError('Password for authentication is missing')
+
+    if (dict_search('authentication.password', openvpn) and not
+        dict_search('authentication.username', openvpn)):
+            raise ConfigError('Username for authentication is missing')
+
+    verify_vrf(openvpn)
+    verify_bond_bridge_member(openvpn)
+    verify_mirror_redirect(openvpn)
+
+    return None
+
+def generate_pki_files(openvpn):
+    pki = openvpn['pki']
+    if not pki:
+        return None
+
+    interface = openvpn['ifname']
+    shared_secret_key = dict_search_args(openvpn, 'shared_secret_key')
+    tls = dict_search_args(openvpn, 'tls')
+
+    if shared_secret_key:
+        pki_key = pki['openvpn']['shared_secret'][shared_secret_key]
+        key_path = os.path.join(cfg_dir, f'{interface}_shared.key')
+        write_file(key_path, wrap_openvpn_key(pki_key['key']),
+                   user=user, group=group)
+
+    if tls:
+        if 'ca_certificate' in tls:
+            cert_path = os.path.join(cfg_dir, f'{interface}_ca.pem')
+            crl_path = os.path.join(cfg_dir, f'{interface}_crl.pem')
+
+            if os.path.exists(cert_path):
+                os.unlink(cert_path)
+
+            if os.path.exists(crl_path):
+                os.unlink(crl_path)
+
+            for cert_name in sort_ca_chain(tls['ca_certificate'], pki['ca']):
+                pki_ca = pki['ca'][cert_name]
+
+                if 'certificate' in pki_ca:
+                    write_file(cert_path, wrap_certificate(pki_ca['certificate']) + "\n",
+                               user=user, group=group, mode=0o600, append=True)
+
+                if 'crl' in pki_ca:
+                    for crl in pki_ca['crl']:
+                        write_file(crl_path, wrap_crl(crl) + "\n", user=user, group=group,
+                                   mode=0o600, append=True)
+
+                    openvpn['tls']['crl'] = True
+
+        if 'certificate' in tls:
+            cert_name = tls['certificate']
+            pki_cert = pki['certificate'][cert_name]
+
+            if 'certificate' in pki_cert:
+                cert_path = os.path.join(cfg_dir, f'{interface}_cert.pem')
+                write_file(cert_path, wrap_certificate(pki_cert['certificate']),
+                           user=user, group=group, mode=0o600)
+
+            if 'private' in pki_cert and 'key' in pki_cert['private']:
+                key_path = os.path.join(cfg_dir, f'{interface}_cert.key')
+                write_file(key_path, wrap_private_key(pki_cert['private']['key']),
+                           user=user, group=group, mode=0o600)
+
+                openvpn['tls']['private_key'] = True
+
+        if 'dh_params' in tls:
+            dh_name = tls['dh_params']
+            pki_dh = pki['dh'][dh_name]
+
+            if 'parameters' in pki_dh:
+                dh_path = os.path.join(cfg_dir, f'{interface}_dh.pem')
+                write_file(dh_path, wrap_dh_parameters(pki_dh['parameters']),
+                           user=user, group=group, mode=0o600)
+
+        if 'auth_key' in tls:
+            key_name = tls['auth_key']
+            pki_key = pki['openvpn']['shared_secret'][key_name]
+
+            if 'key' in pki_key:
+                key_path = os.path.join(cfg_dir, f'{interface}_auth.key')
+                write_file(key_path, wrap_openvpn_key(pki_key['key']),
+                           user=user, group=group, mode=0o600)
+
+        if 'crypt_key' in tls:
+            key_name = tls['crypt_key']
+            pki_key = pki['openvpn']['shared_secret'][key_name]
+
+            if 'key' in pki_key:
+                key_path = os.path.join(cfg_dir, f'{interface}_crypt.key')
+                write_file(key_path, wrap_openvpn_key(pki_key['key']),
+                           user=user, group=group, mode=0o600)
+
+
+def generate(openvpn):
+    interface = openvpn['ifname']
+    directory = os.path.dirname(cfg_file.format(**openvpn))
+    openvpn['plugin_dir'] = '/usr/lib/openvpn'
+    # create base config directory on demand
+    makedir(directory, user, group)
+    # enforce proper permissions on /run/openvpn
+    chown(directory, user, group)
+
+    # we can't know in advance which clients have been removed,
+    # thus all client configs will be removed and re-added on demand
+    ccd_dir = os.path.join(directory, 'ccd', interface)
+    if os.path.isdir(ccd_dir):
+        rmtree(ccd_dir, ignore_errors=True)
+
+    # Remove systemd directories with overrides
+    service_dir = os.path.dirname(service_file.format(**openvpn))
+    if os.path.isdir(service_dir):
+        rmtree(service_dir, ignore_errors=True)
+
+    if 'deleted' in openvpn or 'disable' in openvpn:
+        return None
+
+    # create client config directory on demand
+    makedir(ccd_dir, user, group)
+
+    # Fix file permissons for keys
+    generate_pki_files(openvpn)
+
+    # Generate User/Password authentication file
+    if 'authentication' in openvpn:
+        render(openvpn['auth_user_pass_file'], 'openvpn/auth.pw.j2', openvpn,
+               user=user, group=group, permission=0o600)
+    else:
+        # delete old auth file if present
+        if os.path.isfile(openvpn['auth_user_pass_file']):
+            os.remove(openvpn['auth_user_pass_file'])
+
+    # Generate client specific configuration
+    server_client = dict_search_args(openvpn, 'server', 'client')
+    if server_client:
+        for client, client_config in server_client.items():
+            client_file = os.path.join(ccd_dir, client)
+
+            # Our client need's to know its subnet mask ...
+            client_config['server_subnet'] = dict_search('server.subnet', openvpn)
+
+            render(client_file, 'openvpn/client.conf.j2', client_config,
+                   user=user, group=group)
+
+    # we need to support quoting of raw parameters from OpenVPN CLI
+    # see https://vyos.dev/T1632
+    render(cfg_file.format(**openvpn), 'openvpn/server.conf.j2', openvpn,
+           formater=lambda _: _.replace("&quot;", '"'), user=user, group=group)
+
+    # Render 20-override.conf for OpenVPN service
+    render(service_file.format(**openvpn), 'openvpn/service-override.conf.j2', openvpn,
+           formater=lambda _: _.replace("&quot;", '"'), user=user, group=group)
+    # Reload systemd services config to apply an override
+    call(f'systemctl daemon-reload')
+
+    return None
+
+def apply(openvpn):
+    interface = openvpn['ifname']
+
+    # Do some cleanup when OpenVPN is disabled/deleted
+    if 'deleted' in openvpn or 'disable' in openvpn:
+        call(f'systemctl stop openvpn@{interface}.service')
+        for cleanup_file in glob(f'/run/openvpn/{interface}.*'):
+            if os.path.isfile(cleanup_file):
+                os.unlink(cleanup_file)
+
+        if interface in interfaces():
+            VTunIf(interface).remove()
+
+    # dynamically load/unload DCO Kernel extension if requested
+    dco_module = 'ovpn_dco_v2'
+    if 'module_load_dco' in openvpn:
+        check_kmod(dco_module)
+    else:
+        unload_kmod(dco_module)
+
+    # Now bail out early if interface is disabled or got deleted
+    if 'deleted' in openvpn or 'disable' in openvpn:
+        return None
+
+    # verify specified IP address is present on any interface on this system
+    # Allow to bind service to nonlocal address, if it virtaual-vrrp address
+    # or if address will be assign later
+    if 'local_host' in openvpn:
+        if not is_addr_assigned(openvpn['local_host']):
+            cmd('sysctl -w net.ipv4.ip_nonlocal_bind=1')
+
+    # No matching OpenVPN process running - maybe it got killed or none
+    # existed - nevertheless, spawn new OpenVPN process
+    action = 'reload-or-restart'
+    if 'restart_required' in openvpn:
+        action = 'restart'
+    call(f'systemctl {action} openvpn@{interface}.service')
+
+    o = VTunIf(**openvpn)
+    o.update(openvpn)
+
+    return None
+
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)
+