# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import contextlib
import os
import subprocess
from eventlet import semaphore
from oslo_config import cfg
from oslo_log import log
from ironic_inspector.common.i18n import _LE, _LW
from ironic_inspector.common import ironic as ir_utils
from ironic_inspector import node_cache
CONF = cfg.CONF
LOG = log.getLogger("ironic_inspector.firewall")
NEW_CHAIN = None
CHAIN = None
INTERFACE = None
LOCK = semaphore.BoundedSemaphore()
BASE_COMMAND = None
BLACKLIST_CACHE = None
ENABLED = True
def _iptables(*args, **kwargs):
# NOTE(dtantsur): -w flag makes it wait for xtables lock
cmd = BASE_COMMAND + args
ignore = kwargs.pop('ignore', False)
LOG.debug('Running iptables %s', args)
kwargs['stderr'] = subprocess.STDOUT
try:
subprocess.check_output(cmd, **kwargs)
except subprocess.CalledProcessError as exc:
output = exc.output.replace('\n', '. ')
if ignore:
LOG.debug('Ignoring failed iptables %(args)s: %(output)s',
{'args': args, 'output': output})
else:
LOG.error(_LE('iptables %(iptables)s failed: %(exc)s') %
{'iptables': args, 'exc': output})
raise
[docs]def init():
"""Initialize firewall management.
Must be called one on start-up.
"""
if not CONF.firewall.manage_firewall:
return
global INTERFACE, CHAIN, NEW_CHAIN, BASE_COMMAND, BLACKLIST_CACHE
BLACKLIST_CACHE = None
INTERFACE = CONF.firewall.dnsmasq_interface
CHAIN = CONF.firewall.firewall_chain
NEW_CHAIN = CHAIN + '_temp'
BASE_COMMAND = ('sudo', 'ironic-inspector-rootwrap',
CONF.rootwrap_config, 'iptables',)
# -w flag makes iptables wait for xtables lock, but it's not supported
# everywhere yet
try:
with open(os.devnull, 'wb') as null:
subprocess.check_call(BASE_COMMAND + ('-w', '-h'),
stderr=null, stdout=null)
except subprocess.CalledProcessError:
LOG.warning(_LW('iptables does not support -w flag, please update '
'it to at least version 1.4.21'))
else:
BASE_COMMAND += ('-w',)
_clean_up(CHAIN)
# Not really needed, but helps to validate that we have access to iptables
_iptables('-N', CHAIN)
def _clean_up(chain):
_iptables('-D', 'INPUT', '-i', INTERFACE, '-p', 'udp',
'--dport', '67', '-j', chain,
ignore=True)
_iptables('-F', chain, ignore=True)
_iptables('-X', chain, ignore=True)
[docs]def clean_up():
"""Clean up everything before exiting."""
if not CONF.firewall.manage_firewall:
return
_clean_up(CHAIN)
_clean_up(NEW_CHAIN)
def _should_enable_dhcp():
"""Check whether we should enable DHCP at all.
We won't even open our DHCP if no nodes are on introspection and
node_not_found_hook is not set.
"""
return (node_cache.introspection_active() or
CONF.processing.node_not_found_hook)
@contextlib.contextmanager
def _temporary_chain(chain, main_chain):
"""Context manager to operate on a temporary chain."""
# Clean up a bit to account for possible troubles on previous run
_clean_up(chain)
_iptables('-N', chain)
yield
# Swap chains
_iptables('-I', 'INPUT', '-i', INTERFACE, '-p', 'udp',
'--dport', '67', '-j', chain)
_iptables('-D', 'INPUT', '-i', INTERFACE, '-p', 'udp',
'--dport', '67', '-j', main_chain,
ignore=True)
_iptables('-F', main_chain, ignore=True)
_iptables('-X', main_chain, ignore=True)
_iptables('-E', chain, main_chain)
def _disable_dhcp():
"""Disable DHCP completely."""
global ENABLED, BLACKLIST_CACHE
if not ENABLED:
LOG.debug('DHCP is already disabled, not updating')
return
LOG.debug('No nodes on introspection and node_not_found_hook is '
'not set - disabling DHCP')
BLACKLIST_CACHE = None
with _temporary_chain(NEW_CHAIN, CHAIN):
# Blacklist everything
_iptables('-A', NEW_CHAIN, '-j', 'REJECT')
ENABLED = False
[docs]def update_filters(ironic=None):
"""Update firewall filter rules for introspection.
Gives access to PXE boot port for any machine, except for those,
whose MAC is registered in Ironic and is not on introspection right now.
This function is called from both introspection initialization code and
from periodic task. This function is supposed to be resistant to unexpected
iptables state.
``init()`` function must be called once before any call to this function.
This function is using ``eventlet`` semaphore to serialize access from
different green threads.
Does nothing, if firewall management is disabled in configuration.
:param ironic: Ironic client instance, optional.
"""
global BLACKLIST_CACHE, ENABLED
if not CONF.firewall.manage_firewall:
return
assert INTERFACE is not None
ironic = ir_utils.get_client() if ironic is None else ironic
with LOCK:
if not _should_enable_dhcp():
_disable_dhcp()
return
macs_active = set(p.address for p in ironic.port.list(limit=0))
to_blacklist = macs_active - node_cache.active_macs()
if BLACKLIST_CACHE is not None and to_blacklist == BLACKLIST_CACHE:
LOG.debug('Not updating iptables - no changes in MAC list %s',
to_blacklist)
return
LOG.debug('Blacklisting active MAC\'s %s', to_blacklist)
# Force update on the next iteration if this attempt fails
BLACKLIST_CACHE = None
with _temporary_chain(NEW_CHAIN, CHAIN):
# - Blacklist active macs, so that nova can boot them
for mac in to_blacklist:
_iptables('-A', NEW_CHAIN, '-m', 'mac',
'--mac-source', mac, '-j', 'DROP')
# - Whitelist everything else
_iptables('-A', NEW_CHAIN, '-j', 'ACCEPT')
# Cache result of successful iptables update
ENABLED = True
BLACKLIST_CACHE = to_blacklist