Source code for ironic_inspector.firewall

# 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.
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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 %s: %s', args, 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

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