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# Copyright VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library. If not, see <http://www.gnu.org/licenses/>.
# T8264: "offload dco" used to be accepted next to settings the Kernel module
# can not serve, because OpenVPN 2.6 silently ignored the module. Now that the
# offload is real those combinations are rejected, so drop the request from
# configurations that would otherwise fail to load.
#
# T9363: site-to-site rendered "ping-restart <failure-count>", so the count
# landed as a number of seconds while the server has always rendered
# interval * failure-count. Now that both agree, a timeout OpenVPN refuses is
# reachable in site-to-site too, so the same clamp has to cover it.
from vyos.configtree import ConfigTree
base = ['interfaces', 'openvpn']
dco_ciphers = ['aes128gcm', 'aes192gcm', 'aes256gcm']
dco_incompatible_options = [
'comp-lzo',
'disable-dco',
'fragment',
'http-proxy',
'management-query-proxy',
'socks-proxy',
]
dco_conditional_options = {
'allow-compression': 'no',
'compress': 'migrate',
'dev-type': 'tun',
}
dco_cipher_options = ['data-ciphers', 'data-ciphers-fallback', 'ncp-ciphers']
dco_raw_ciphers = ['AES-128-GCM', 'AES-192-GCM', 'AES-256-GCM', 'CHACHA20-POLY1305']
def _offloadable_ciphers(value: str) -> bool:
"""Whether every cipher of a raw negotiation list can be offloaded."""
for cipher in value.split(':'):
# "DEFAULT" stands for the built-in list, which OpenVPN expands - case
# sensitively, and only as a bare token - to AEAD ciphers alone before
# it weighs the offload
if cipher == 'DEFAULT':
continue
# it strips exactly one "?", and drops such a cipher only when it does
# not know it at all, so an optional one still has to be offloadable
name = cipher[1:] if cipher.startswith('?') else cipher
if name.upper() not in dco_raw_ciphers:
return False
return True
def _offloadable(options: list, mode: str) -> bool:
"""Whether every raw option leaves the data path offloadable."""
# site-to-site renders neither "client" nor "server", and OpenVPN then
# takes a raw "--cipher" as the fallback cipher
cipher_options = dco_cipher_options
if mode == 'site-to-site':
cipher_options = cipher_options + ['cipher']
# "topology" only reaches OpenVPN's decision in server mode
conditional_options = dco_conditional_options
if mode == 'server':
conditional_options = {**conditional_options, 'topology': 'subnet'}
for option in options:
tmp = option.split()
if not tmp:
continue
keyword = tmp[0].lstrip('-')
if keyword in dco_incompatible_options:
return False
keep = conditional_options.get(keyword)
if keep is not None and tmp[1:] != [keep]:
return False
# only an AF_UNIX node rules out the offload, a real one is fine
if keyword == 'dev-node' and tmp[1:] and tmp[1].startswith('unix:'):
return False
if keyword in cipher_options and tmp[1:]:
if not _offloadable_ciphers(tmp[1]):
return False
return True
def _value(config: ConfigTree, path: list):
# return_value() raises on a missing path, and nodes carrying a CLI
# default are usually absent from a saved configuration
return config.return_value(path) if config.exists(path) else None
def _clamp_keepalive(config: ConfigTree, path: list) -> None:
"""Bring a keepalive within what verify() accepts."""
mode = _value(config, path + ['mode'])
if mode not in ['server', 'site-to-site']:
return
# both nodes carry a CLI default, so they render even when absent
interval = int(_value(config, path + ['keep-alive', 'interval']) or 10)
count = int(_value(config, path + ['keep-alive', 'failure-count']) or 60)
# a zero interval renders "keepalive 0 0" and turns keepalive off, which
# OpenVPN and verify() both leave alone
if interval < 1:
return
if mode == 'site-to-site':
# site-to-site renders "ping-restart" itself, which OpenVPN caps at
# 24 hours and does not double. It carries no "at least twice the
# interval" rule either, since that one belongs to "keepalive".
wanted = min(count, 86400 // interval)
else:
# the timeout is interval * failure-count: it has to reach twice the
# interval and stay below 12 hours. Beyond an interval of 21600 no
# count satisfies both - the CLI range stops at 600, so only a
# hand-edited configuration gets there and its interval is rejected
# anyway.
wanted = min(max(count, 2), max(2, 43200 // interval))
if wanted != count:
config.set(path + ['keep-alive', 'failure-count'], value=str(wanted))
def migrate(config: ConfigTree) -> None:
if not config.exists(base):
return
for interface in config.list_nodes(base):
path = base + [interface]
# unrelated to the offload, so it runs for every interface
_clamp_keepalive(config, path)
if not config.exists(path + ['offload', 'dco']):
continue
ciphers = []
if config.exists(path + ['encryption', 'data-ciphers']):
ciphers += config.return_values(path + ['encryption', 'data-ciphers'])
fallback = _value(config, path + ['encryption', 'data-ciphers-fallback'])
if fallback:
ciphers.append(fallback)
options = []
if config.exists(path + ['openvpn-option']):
options = config.return_values(path + ['openvpn-option'])
mode = _value(config, path + ['mode'])
topology = None
if mode == 'server':
topology = _value(config, path + ['server', 'topology'])
if (
_value(config, path + ['device-type']) == 'tap'
or config.exists(path + ['shared-secret-key'])
or config.exists(path + ['use-lzo-compression'])
or (topology is not None and topology != 'subnet')
or any(cipher not in dco_ciphers for cipher in ciphers)
or not _offloadable(options, mode)
):
offload = path + ['offload']
config.delete(offload + ['dco'])
if config.exists(offload) and not config.list_nodes(offload):
config.delete(offload)
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