Beispiel #1
0
class Firewall(object):
    def __init__(self, offline=False):
        self._firewalld_conf = firewalld_conf(config.FIREWALLD_CONF)
        self._offline = offline

        if self._offline:
            self.ip4tables_enabled = False
            self.ip6tables_enabled = False
            self.ebtables_enabled = False
            self.ipset_enabled = False
            self.ipset_supported_types = IPSET_TYPES
            self.nftables_enabled = False
        else:
            self.ip4tables_backend = ipXtables.ip4tables(self)
            self.ip4tables_enabled = True
            self.ipv4_supported_icmp_types = []
            self.ip6tables_backend = ipXtables.ip6tables(self)
            self.ip6tables_enabled = True
            self.ipv6_supported_icmp_types = []
            self.ebtables_backend = ebtables.ebtables()
            self.ebtables_enabled = True
            self.ipset_backend = ipset.ipset()
            self.ipset_enabled = True
            self.ipset_supported_types = []
            self.nftables_backend = nftables.nftables(self)
            self.nftables_enabled = True

            self.modules_backend = modules.modules()

        self.icmptype = FirewallIcmpType(self)
        self.service = FirewallService(self)
        self.zone = FirewallZone(self)
        self.direct = FirewallDirect(self)
        self.config = FirewallConfig(self)
        self.policies = FirewallPolicies()
        self.ipset = FirewallIPSet(self)
        self.helper = FirewallHelper(self)
        self.policy = FirewallPolicy(self)

        self.__init_vars()

    def __repr__(self):
        return '%s(%r, %r, %r, %r, %r, %r, %r, %r, %r, %r, %r, %r, %r)' % \
            (self.__class__, self.ip4tables_enabled, self.ip6tables_enabled,
             self.ebtables_enabled, self._state, self._panic,
             self._default_zone, self._module_refcount, self._marks,
             self.cleanup_on_exit, self.ipv6_rpfilter_enabled,
             self.ipset_enabled, self._individual_calls, self._log_denied)

    def __init_vars(self):
        self._state = "INIT"
        self._panic = False
        self._default_zone = ""
        self._module_refcount = {}
        self._marks = []
        # fallback settings will be overloaded by firewalld.conf
        self.cleanup_on_exit = config.FALLBACK_CLEANUP_ON_EXIT
        self.ipv6_rpfilter_enabled = config.FALLBACK_IPV6_RPFILTER
        self._individual_calls = config.FALLBACK_INDIVIDUAL_CALLS
        self._log_denied = config.FALLBACK_LOG_DENIED
        self._firewall_backend = config.FALLBACK_FIREWALL_BACKEND
        self._flush_all_on_reload = config.FALLBACK_FLUSH_ALL_ON_RELOAD
        self._rfc3964_ipv4 = config.FALLBACK_RFC3964_IPV4
        self._allow_zone_drifting = config.FALLBACK_ALLOW_ZONE_DRIFTING

    def _check_tables(self):
        # check if iptables, ip6tables and ebtables are usable, else disable
        if self.ip4tables_enabled and \
           "filter" not in self.get_backend_by_ipv("ipv4").get_available_tables():
            log.warning("iptables not usable, disabling IPv4 firewall.")
            self.ip4tables_enabled = False

        if self.ip6tables_enabled and \
           "filter" not in self.get_backend_by_ipv("ipv6").get_available_tables():
            log.warning("ip6tables not usable, disabling IPv6 firewall.")
            self.ip6tables_enabled = False

        if self.ebtables_enabled and \
           "filter" not in self.get_backend_by_ipv("eb").get_available_tables():
            log.warning(
                "ebtables not usable, disabling ethernet bridge firewall.")
            self.ebtables_enabled = False

        # is there at least support for ipv4 or ipv6
        if not self.ip4tables_enabled and not self.ip6tables_enabled \
           and not self.nftables_enabled:
            log.fatal("No IPv4 and IPv6 firewall.")
            sys.exit(1)

    def _start_check(self):
        try:
            self.ipset_backend.set_list()
        except ValueError:
            log.warning("ipset not usable, disabling ipset usage in firewall.")
            # ipset is not usable, no supported types
            self.ipset_enabled = False
            self.ipset_supported_types = []
        else:
            # ipset is usable, get all supported types
            self.ipset_supported_types = self.ipset_backend.set_supported_types(
            )

        self.ip4tables_backend.fill_exists()
        if not self.ip4tables_backend.restore_command_exists:
            if self.ip4tables_backend.command_exists:
                log.warning("iptables-restore is missing, using "
                            "individual calls for IPv4 firewall.")
            else:
                log.warning("iptables-restore and iptables are missing, "
                            "disabling IPv4 firewall.")
                self.ip4tables_enabled = False
        if self.nftables_enabled:
            self.ipv4_supported_icmp_types = self.nftables_backend.supported_icmp_types(
                "ipv4")
        else:
            if self.ip4tables_enabled:
                self.ipv4_supported_icmp_types = self.ip4tables_backend.supported_icmp_types(
                )
            else:
                self.ipv4_supported_icmp_types = []
        self.ip6tables_backend.fill_exists()
        if not self.ip6tables_backend.restore_command_exists:
            if self.ip6tables_backend.command_exists:
                log.warning("ip6tables-restore is missing, using "
                            "individual calls for IPv6 firewall.")
            else:
                log.warning("ip6tables-restore and ip6tables are missing, "
                            "disabling IPv6 firewall.")
                self.ip6tables_enabled = False
        if self.nftables_enabled:
            self.ipv6_supported_icmp_types = self.nftables_backend.supported_icmp_types(
                "ipv6")
        else:
            if self.ip6tables_enabled:
                self.ipv6_supported_icmp_types = self.ip6tables_backend.supported_icmp_types(
                )
            else:
                self.ipv6_supported_icmp_types = []
        self.ebtables_backend.fill_exists()
        if not self.ebtables_backend.restore_command_exists:
            if self.ebtables_backend.command_exists:
                log.warning("ebtables-restore is missing, using "
                            "individual calls for bridge firewall.")
            else:
                log.warning("ebtables-restore and ebtables are missing, "
                            "disabling bridge firewall.")
                self.ebtables_enabled = False

        if self.ebtables_enabled and not self._individual_calls and \
           not self.ebtables_backend.restore_noflush_option:
            log.debug1("ebtables-restore is not supporting the --noflush "
                       "option, will therefore not be used")

    def _start(self, reload=False, complete_reload=False):
        # initialize firewall
        default_zone = config.FALLBACK_ZONE

        # load firewalld config
        log.debug1("Loading firewalld config file '%s'", config.FIREWALLD_CONF)
        try:
            self._firewalld_conf.read()
        except Exception as msg:
            log.warning(msg)
            log.warning("Using fallback firewalld configuration settings.")
        else:
            if self._firewalld_conf.get("DefaultZone"):
                default_zone = self._firewalld_conf.get("DefaultZone")

            if self._firewalld_conf.get("CleanupOnExit"):
                value = self._firewalld_conf.get("CleanupOnExit")
                if value is not None and value.lower() in ["no", "false"]:
                    self.cleanup_on_exit = False
                log.debug1("CleanupOnExit is set to '%s'",
                           self.cleanup_on_exit)

            if self._firewalld_conf.get("Lockdown"):
                value = self._firewalld_conf.get("Lockdown")
                if value is not None and value.lower() in ["yes", "true"]:
                    log.debug1("Lockdown is enabled")
                    try:
                        self.policies.enable_lockdown()
                    except FirewallError:
                        # already enabled, this is probably reload
                        pass

            if self._firewalld_conf.get("IPv6_rpfilter"):
                value = self._firewalld_conf.get("IPv6_rpfilter")
                if value is not None:
                    if value.lower() in ["no", "false"]:
                        self.ipv6_rpfilter_enabled = False
                    if value.lower() in ["yes", "true"]:
                        self.ipv6_rpfilter_enabled = True
            if self.ipv6_rpfilter_enabled:
                log.debug1("IPv6 rpfilter is enabled")
            else:
                log.debug1("IPV6 rpfilter is disabled")

            if self._firewalld_conf.get("IndividualCalls"):
                value = self._firewalld_conf.get("IndividualCalls")
                if value is not None and value.lower() in ["yes", "true"]:
                    log.debug1("IndividualCalls is enabled")
                    self._individual_calls = True

            if self._firewalld_conf.get("LogDenied"):
                value = self._firewalld_conf.get("LogDenied")
                if value is None or value.lower() == "no":
                    self._log_denied = "off"
                else:
                    self._log_denied = value.lower()
                    log.debug1("LogDenied is set to '%s'", self._log_denied)

            if self._firewalld_conf.get("FirewallBackend"):
                self._firewall_backend = self._firewalld_conf.get(
                    "FirewallBackend")
                log.debug1("FirewallBackend is set to '%s'",
                           self._firewall_backend)

            if self._firewalld_conf.get("FlushAllOnReload"):
                value = self._firewalld_conf.get("FlushAllOnReload")
                if value.lower() in ["no", "false"]:
                    self._flush_all_on_reload = False
                else:
                    self._flush_all_on_reload = True
                log.debug1("FlushAllOnReload is set to '%s'",
                           self._flush_all_on_reload)

            if self._firewalld_conf.get("RFC3964_IPv4"):
                value = self._firewalld_conf.get("RFC3964_IPv4")
                if value.lower() in ["no", "false"]:
                    self._rfc3964_ipv4 = False
                else:
                    self._rfc3964_ipv4 = True
                log.debug1("RFC3964_IPv4 is set to '%s'", self._rfc3964_ipv4)

            if self._firewalld_conf.get("AllowZoneDrifting"):
                value = self._firewalld_conf.get("AllowZoneDrifting")
                if value.lower() in ["no", "false"]:
                    self._allow_zone_drifting = False
                else:
                    self._allow_zone_drifting = True
                    if not self._offline:
                        log.warning(
                            "AllowZoneDrifting is enabled. This is considered "
                            "an insecure configuration option. It will be "
                            "removed in a future release. Please consider "
                            "disabling it now.")
                log.debug1("AllowZoneDrifting is set to '%s'",
                           self._allow_zone_drifting)

        self.config.set_firewalld_conf(copy.deepcopy(self._firewalld_conf))

        self._select_firewall_backend(self._firewall_backend)

        if not self._offline:
            self._start_check()

        # load lockdown whitelist
        log.debug1("Loading lockdown whitelist")
        try:
            self.policies.lockdown_whitelist.read()
        except Exception as msg:
            if self.policies.query_lockdown():
                log.error("Failed to load lockdown whitelist '%s': %s",
                          self.policies.lockdown_whitelist.filename, msg)
            else:
                log.debug1("Failed to load lockdown whitelist '%s': %s",
                           self.policies.lockdown_whitelist.filename, msg)

        # copy policies to config interface
        self.config.set_policies(copy.deepcopy(self.policies))

        # load ipset files
        self._loader(config.FIREWALLD_IPSETS, "ipset")
        self._loader(config.ETC_FIREWALLD_IPSETS, "ipset")

        # load icmptype files
        self._loader(config.FIREWALLD_ICMPTYPES, "icmptype")
        self._loader(config.ETC_FIREWALLD_ICMPTYPES, "icmptype")

        if len(self.icmptype.get_icmptypes()) == 0:
            log.error("No icmptypes found.")

        # load helper files
        self._loader(config.FIREWALLD_HELPERS, "helper")
        self._loader(config.ETC_FIREWALLD_HELPERS, "helper")

        # load service files
        self._loader(config.FIREWALLD_SERVICES, "service")
        self._loader(config.ETC_FIREWALLD_SERVICES, "service")

        if len(self.service.get_services()) == 0:
            log.error("No services found.")

        # load zone files
        self._loader(config.FIREWALLD_ZONES, "zone")
        self._loader(config.ETC_FIREWALLD_ZONES, "zone")

        if len(self.zone.get_zones()) == 0:
            log.fatal("No zones found.")
            sys.exit(1)

        # load policy files
        self._loader(config.FIREWALLD_POLICIES, "policy")
        self._loader(config.ETC_FIREWALLD_POLICIES, "policy")

        # check minimum required zones
        error = False
        for z in ["block", "drop", "trusted"]:
            if z not in self.zone.get_zones():
                log.fatal("Zone '%s' is not available.", z)
                error = True
        if error:
            sys.exit(1)

        # check if default_zone is a valid zone
        if default_zone not in self.zone.get_zones():
            if "public" in self.zone.get_zones():
                zone = "public"
            elif "external" in self.zone.get_zones():
                zone = "external"
            else:
                zone = "block"  # block is a base zone, therefore it has to exist

            log.error("Default zone '%s' is not valid. Using '%s'.",
                      default_zone, zone)
            default_zone = zone
        else:
            log.debug1("Using default zone '%s'", default_zone)

        # load direct rules
        obj = Direct(config.FIREWALLD_DIRECT)
        if os.path.exists(config.FIREWALLD_DIRECT):
            log.debug1("Loading direct rules file '%s'" % \
                       config.FIREWALLD_DIRECT)
            try:
                obj.read()
            except Exception as msg:
                log.error("Failed to load direct rules file '%s': %s",
                          config.FIREWALLD_DIRECT, msg)
        self.direct.set_permanent_config(obj)
        self.config.set_direct(copy.deepcopy(obj))

        self._default_zone = self.check_zone(default_zone)

        if self._offline:
            return

        # check if needed tables are there
        self._check_tables()

        if log.getDebugLogLevel() > 0:
            # get time before flushing and applying
            tm1 = time.time()

        # Start transaction
        transaction = FirewallTransaction(self)

        # flush rules
        self.flush(use_transaction=transaction)

        # If modules need to be unloaded in complete reload or if there are
        # ipsets to get applied, limit the transaction to flush.
        #
        # Future optimization for the ipset case in reload: The transaction
        # only needs to be split here if there are conflicting ipset types in
        # exsting ipsets and the configuration in firewalld.
        if (reload and complete_reload) or \
           (self.ipset_enabled and self.ipset.has_ipsets()):
            transaction.execute(True)
            transaction.clear()

        # complete reload: unload modules also
        if reload and complete_reload:
            log.debug1("Unloading firewall modules")
            self.modules_backend.unload_firewall_modules()

        self.apply_default_tables(use_transaction=transaction)
        transaction.execute(True)
        transaction.clear()

        # apply settings for loaded ipsets while reloading here
        if self.ipset_enabled and self.ipset.has_ipsets():
            log.debug1("Applying ipsets")
            self.ipset.apply_ipsets()

        # Start or continue with transaction

        # apply default rules
        log.debug1("Applying default rule set")
        self.apply_default_rules(use_transaction=transaction)

        # apply settings for loaded zones
        log.debug1("Applying used zones")
        self.zone.apply_zones(use_transaction=transaction)

        self.zone.change_default_zone(None,
                                      self._default_zone,
                                      use_transaction=transaction)

        # apply policies
        log.debug1("Applying used policies")
        self.policy.apply_policies(use_transaction=transaction)

        # Execute transaction
        transaction.execute(True)

        # Start new transaction for direct rules
        transaction.clear()

        # apply direct chains, rules and passthrough rules
        if self.direct.has_configuration():
            log.debug1("Applying direct chains rules and passthrough rules")
            self.direct.apply_direct(transaction)

            # since direct rules are easy to make syntax errors lets highlight
            # the cause if the transaction fails.
            try:
                transaction.execute(True)
                transaction.clear()
            except FirewallError as e:
                raise FirewallError(e.code,
                                    "Direct: %s" % (e.msg if e.msg else ""))
            except Exception:
                raise

        del transaction

        if log.getDebugLogLevel() > 1:
            # get time after flushing and applying
            tm2 = time.time()
            log.debug2("Flushing and applying took %f seconds" % (tm2 - tm1))

    def start(self):
        try:
            self._start()
        except Exception:
            self._state = "FAILED"
            self.set_policy("ACCEPT")
            raise
        else:
            self._state = "RUNNING"
            self.set_policy("ACCEPT")

    def _loader(self, path, reader_type, combine=False):
        # combine: several zone files are getting combined into one obj
        if not os.path.isdir(path):
            return

        if combine:
            if path.startswith(config.ETC_FIREWALLD) and reader_type == "zone":
                combined_zone = Zone()
                combined_zone.name = os.path.basename(path)
                combined_zone.check_name(combined_zone.name)
                combined_zone.path = path
                combined_zone.default = False
            else:
                combine = False

        for filename in sorted(os.listdir(path)):
            if not filename.endswith(".xml"):
                if path.startswith(config.ETC_FIREWALLD) and \
                        reader_type == "zone" and \
                        os.path.isdir("%s/%s" % (path, filename)):
                    self._loader("%s/%s" % (path, filename),
                                 reader_type,
                                 combine=True)
                continue

            name = "%s/%s" % (path, filename)
            log.debug1("Loading %s file '%s'", reader_type, name)
            try:
                if reader_type == "icmptype":
                    obj = icmptype_reader(filename, path)
                    if obj.name in self.icmptype.get_icmptypes():
                        orig_obj = self.icmptype.get_icmptype(obj.name)
                        log.debug1("  Overloads %s '%s' ('%s/%s')",
                                   reader_type, orig_obj.name, orig_obj.path,
                                   orig_obj.filename)
                        self.icmptype.remove_icmptype(orig_obj.name)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                    try:
                        self.icmptype.add_icmptype(obj)
                    except FirewallError as error:
                        log.info1("%s: %s, ignoring for run-time." % \
                                    (obj.name, str(error)))
                    # add a deep copy to the configuration interface
                    self.config.add_icmptype(copy.deepcopy(obj))
                elif reader_type == "service":
                    obj = service_reader(filename, path)
                    if obj.name in self.service.get_services():
                        orig_obj = self.service.get_service(obj.name)
                        log.debug1("  Overloads %s '%s' ('%s/%s')",
                                   reader_type, orig_obj.name, orig_obj.path,
                                   orig_obj.filename)
                        self.service.remove_service(orig_obj.name)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                    self.service.add_service(obj)
                    # add a deep copy to the configuration interface
                    self.config.add_service(copy.deepcopy(obj))
                elif reader_type == "zone":
                    obj = zone_reader(filename, path, no_check_name=combine)
                    if combine:
                        # Change name for permanent configuration
                        obj.name = "%s/%s" % (os.path.basename(path),
                                              os.path.basename(filename)[0:-4])
                        obj.check_name(obj.name)
                    # Copy object before combine
                    config_obj = copy.deepcopy(obj)
                    if obj.name in self.zone.get_zones():
                        orig_obj = self.zone.get_zone(obj.name)
                        self.zone.remove_zone(orig_obj.name)
                        if orig_obj.combined:
                            log.debug1("  Combining %s '%s' ('%s/%s')",
                                       reader_type, obj.name, path, filename)
                            obj.combine(orig_obj)
                        else:
                            log.debug1("  Overloads %s '%s' ('%s/%s')",
                                       reader_type, orig_obj.name,
                                       orig_obj.path, orig_obj.filename)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                        config_obj.default = True
                    self.config.add_zone(config_obj)
                    if combine:
                        log.debug1("  Combining %s '%s' ('%s/%s')",
                                   reader_type, combined_zone.name, path,
                                   filename)
                        combined_zone.combine(obj)
                    else:
                        self.zone.add_zone(obj)
                elif reader_type == "ipset":
                    obj = ipset_reader(filename, path)
                    if obj.name in self.ipset.get_ipsets():
                        orig_obj = self.ipset.get_ipset(obj.name)
                        log.debug1("  Overloads %s '%s' ('%s/%s')",
                                   reader_type, orig_obj.name, orig_obj.path,
                                   orig_obj.filename)
                        self.ipset.remove_ipset(orig_obj.name)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                    try:
                        self.ipset.add_ipset(obj)
                    except FirewallError as error:
                        log.warning("%s: %s, ignoring for run-time." % \
                                    (obj.name, str(error)))
                    # add a deep copy to the configuration interface
                    self.config.add_ipset(copy.deepcopy(obj))
                elif reader_type == "helper":
                    obj = helper_reader(filename, path)
                    if obj.name in self.helper.get_helpers():
                        orig_obj = self.helper.get_helper(obj.name)
                        log.debug1("  Overloads %s '%s' ('%s/%s')",
                                   reader_type, orig_obj.name, orig_obj.path,
                                   orig_obj.filename)
                        self.helper.remove_helper(orig_obj.name)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                    self.helper.add_helper(obj)
                    # add a deep copy to the configuration interface
                    self.config.add_helper(copy.deepcopy(obj))
                elif reader_type == "policy":
                    obj = policy_reader(filename, path)
                    if obj.name in self.policy.get_policies():
                        orig_obj = self.policy.get_policy(obj.name)
                        log.debug1("  Overloads %s '%s' ('%s/%s')",
                                   reader_type, orig_obj.name, orig_obj.path,
                                   orig_obj.filename)
                        self.policy.remove_policy(orig_obj.name)
                    elif obj.path.startswith(config.ETC_FIREWALLD):
                        obj.default = True
                    self.policy.add_policy(obj)
                    # add a deep copy to the configuration interface
                    self.config.add_policy_object(copy.deepcopy(obj))
                else:
                    log.fatal("Unknown reader type %s", reader_type)
            except FirewallError as msg:
                log.error("Failed to load %s file '%s': %s", reader_type, name,
                          msg)
            except Exception:
                log.error("Failed to load %s file '%s':", reader_type, name)
                log.exception()

        if combine and combined_zone.combined:
            if combined_zone.name in self.zone.get_zones():
                orig_obj = self.zone.get_zone(combined_zone.name)
                log.debug1("  Overloading and deactivating %s '%s' ('%s/%s')",
                           reader_type, orig_obj.name, orig_obj.path,
                           orig_obj.filename)
                try:
                    self.zone.remove_zone(combined_zone.name)
                except Exception:
                    pass
                self.config.forget_zone(combined_zone.name)
            self.zone.add_zone(combined_zone)

    def cleanup(self):
        self.icmptype.cleanup()
        self.service.cleanup()
        self.zone.cleanup()
        self.ipset.cleanup()
        self.helper.cleanup()
        self.config.cleanup()
        self.direct.cleanup()
        self.policies.cleanup()
        self.policy.cleanup()
        self._firewalld_conf.cleanup()
        self.__init_vars()

    def stop(self):
        if self.cleanup_on_exit and not self._offline:
            self.flush()
            self.ipset.flush()
            self.set_policy("ACCEPT")
            self.modules_backend.unload_firewall_modules()

        self.cleanup()

    # handle modules

    def handle_modules(self, _modules, enable):
        num_failed = 0
        error_msgs = ""
        for i, module in enumerate(_modules):
            if enable:
                (status, msg) = self.modules_backend.load_module(module)
            else:
                if self._module_refcount[module] > 1:
                    status = 0  # module referenced more then one, do not unload
                else:
                    (status, msg) = self.modules_backend.unload_module(module)
            if status != 0:
                num_failed += 1
                error_msgs += msg
                continue

            if enable:
                self._module_refcount.setdefault(module, 0)
                self._module_refcount[module] += 1
            else:
                if module in self._module_refcount:
                    self._module_refcount[module] -= 1
                    if self._module_refcount[module] == 0:
                        del self._module_refcount[module]
        return (num_failed, error_msgs)

    def _select_firewall_backend(self, backend):
        if backend != "nftables":
            self.nftables_enabled = False
        # even if using nftables, the other backends are enabled for use with
        # the direct interface. nftables is used for the firewalld primitives.

    def get_backend_by_name(self, name):
        for backend in self.all_backends():
            if backend.name == name:
                return backend
        raise FirewallError(errors.UNKNOWN_ERROR,
                            "'%s' backend does not exist" % name)

    def get_backend_by_ipv(self, ipv):
        if self.nftables_enabled:
            return self.nftables_backend
        if ipv == "ipv4" and self.ip4tables_enabled:
            return self.ip4tables_backend
        elif ipv == "ipv6" and self.ip6tables_enabled:
            return self.ip6tables_backend
        elif ipv == "eb" and self.ebtables_enabled:
            return self.ebtables_backend
        raise FirewallError(
            errors.INVALID_IPV,
            "'%s' is not a valid backend or is unavailable" % ipv)

    def get_direct_backend_by_ipv(self, ipv):
        if ipv == "ipv4" and self.ip4tables_enabled:
            return self.ip4tables_backend
        elif ipv == "ipv6" and self.ip6tables_enabled:
            return self.ip6tables_backend
        elif ipv == "eb" and self.ebtables_enabled:
            return self.ebtables_backend
        raise FirewallError(
            errors.INVALID_IPV,
            "'%s' is not a valid backend or is unavailable" % ipv)

    def is_backend_enabled(self, name):
        if name == "ip4tables":
            return self.ip4tables_enabled
        elif name == "ip6tables":
            return self.ip6tables_enabled
        elif name == "ebtables":
            return self.ebtables_enabled
        elif name == "nftables":
            return self.nftables_enabled
        return False

    def is_ipv_enabled(self, ipv):
        if self.nftables_enabled:
            return True
        if ipv == "ipv4":
            return self.ip4tables_enabled
        elif ipv == "ipv6":
            return self.ip6tables_enabled
        elif ipv == "eb":
            return self.ebtables_enabled
        return False

    def enabled_backends(self):
        backends = []
        if self.nftables_enabled:
            backends.append(self.nftables_backend)
        else:
            if self.ip4tables_enabled:
                backends.append(self.ip4tables_backend)
            if self.ip6tables_enabled:
                backends.append(self.ip6tables_backend)
            if self.ebtables_enabled:
                backends.append(self.ebtables_backend)
        return backends

    def all_backends(self):
        backends = []
        if self.ip4tables_enabled:
            backends.append(self.ip4tables_backend)
        if self.ip6tables_enabled:
            backends.append(self.ip6tables_backend)
        if self.ebtables_enabled:
            backends.append(self.ebtables_backend)
        if self.nftables_enabled:
            backends.append(self.nftables_backend)
        return backends

    def apply_default_tables(self, use_transaction=None):
        if use_transaction is None:
            transaction = FirewallTransaction(self)
        else:
            transaction = use_transaction

        for backend in self.enabled_backends():
            transaction.add_rules(backend, backend.build_default_tables())

        if use_transaction is None:
            transaction.execute(True)

    def apply_default_rules(self, use_transaction=None):
        if use_transaction is None:
            transaction = FirewallTransaction(self)
        else:
            transaction = use_transaction

        for backend in self.enabled_backends():
            rules = backend.build_default_rules(self._log_denied)
            transaction.add_rules(backend, rules)

        if self.is_ipv_enabled("ipv6"):
            ipv6_backend = self.get_backend_by_ipv("ipv6")
            if "raw" in ipv6_backend.get_available_tables():
                if self.ipv6_rpfilter_enabled:
                    rules = ipv6_backend.build_rpfilter_rules(self._log_denied)
                    transaction.add_rules(ipv6_backend, rules)

        if self.is_ipv_enabled("ipv6") and self._rfc3964_ipv4:
            rules = ipv6_backend.build_rfc3964_ipv4_rules()
            transaction.add_rules(ipv6_backend, rules)

        if use_transaction is None:
            transaction.execute(True)

    # flush and policy

    def flush(self, use_transaction=None):
        if use_transaction is None:
            transaction = FirewallTransaction(self)
        else:
            transaction = use_transaction

        log.debug1("Flushing rule set")

        for backend in self.all_backends():
            rules = backend.build_flush_rules()
            transaction.add_rules(backend, rules)

        if use_transaction is None:
            transaction.execute(True)

    def set_policy(self, policy, use_transaction=None):
        if use_transaction is None:
            transaction = FirewallTransaction(self)
        else:
            transaction = use_transaction

        log.debug1("Setting policy to '%s'", policy)

        for backend in self.enabled_backends():
            rules = backend.build_set_policy_rules(policy)
            transaction.add_rules(backend, rules)

        if use_transaction is None:
            transaction.execute(True)

    # rule function used in handle_ functions

    def rule(self, backend_name, rule):
        if not rule:
            return ""

        backend = self.get_backend_by_name(backend_name)
        if not backend:
            raise FirewallError(errors.INVALID_IPV,
                                "'%s' is not a valid backend" % backend_name)

        if not self.is_backend_enabled(backend_name):
            return ""

        return backend.set_rule(rule, self._log_denied)

    def rules(self, backend_name, rules):
        _rules = list(filter(None, rules))

        backend = self.get_backend_by_name(backend_name)
        if not backend:
            raise FirewallError(errors.INVALID_IPV,
                                "'%s' is not a valid backend" % backend_name)

        if not self.is_backend_enabled(backend_name):
            return

        if self._individual_calls or \
           not backend.restore_command_exists or \
           (backend_name == "ebtables" and not self.ebtables_backend.restore_noflush_option):
            for i, rule in enumerate(_rules):
                try:
                    backend.set_rule(rule, self._log_denied)
                except Exception as msg:
                    log.debug1(traceback.format_exc())
                    log.error(msg)
                    for rule in reversed(_rules[:i]):
                        try:
                            backend.set_rule(backend.reverse_rule(rule),
                                             self._log_denied)
                        except Exception:
                            # ignore errors here
                            pass
                    raise msg
        else:
            backend.set_rules(_rules, self._log_denied)

    # check functions

    def check_panic(self):
        if self._panic:
            raise FirewallError(errors.PANIC_MODE)

    def check_policy(self, policy):
        _policy = policy
        if _policy not in self.policy.get_policies():
            raise FirewallError(errors.INVALID_POLICY, _policy)
        return _policy

    def check_zone(self, zone):
        _zone = zone
        if not _zone or _zone == "":
            _zone = self.get_default_zone()
        if _zone not in self.zone.get_zones():
            raise FirewallError(errors.INVALID_ZONE, _zone)
        return _zone

    def check_interface(self, interface):
        if not functions.checkInterface(interface):
            raise FirewallError(errors.INVALID_INTERFACE, interface)

    def check_service(self, service):
        self.service.check_service(service)

    def check_port(self, port):
        if not functions.check_port(port):
            raise FirewallError(errors.INVALID_PORT, port)

    def check_tcpudp(self, protocol):
        if not protocol:
            raise FirewallError(errors.MISSING_PROTOCOL)
        if protocol not in ["tcp", "udp", "sctp", "dccp"]:
            raise FirewallError(errors.INVALID_PROTOCOL,
                                "'%s' not in {'tcp'|'udp'|'sctp'|'dccp'}" % \
                                protocol)

    def check_ip(self, ip):
        if not functions.checkIP(ip):
            raise FirewallError(errors.INVALID_ADDR, ip)

    def check_address(self, ipv, source):
        if ipv == "ipv4":
            if not functions.checkIPnMask(source):
                raise FirewallError(errors.INVALID_ADDR, source)
        elif ipv == "ipv6":
            if not functions.checkIP6nMask(source):
                raise FirewallError(errors.INVALID_ADDR, source)
        else:
            raise FirewallError(errors.INVALID_IPV,
                                "'%s' not in {'ipv4'|'ipv6'}")

    def check_icmptype(self, icmp):
        self.icmptype.check_icmptype(icmp)

    def check_timeout(self, timeout):
        if not isinstance(timeout, int):
            raise TypeError("%s is %s, expected int" %
                            (timeout, type(timeout)))
        if int(timeout) < 0:
            raise FirewallError(
                errors.INVALID_VALUE,
                "timeout '%d' is not positive number" % timeout)

    # RELOAD

    def reload(self, stop=False):
        _panic = self._panic

        # must stash this. The value may change after _start()
        flush_all = self._flush_all_on_reload

        if not flush_all:
            # save zone interfaces
            _zone_interfaces = {}
            for zone in self.zone.get_zones():
                _zone_interfaces[zone] = self.zone.get_settings(
                    zone)["interfaces"]
            # save direct config
            _direct_config = self.direct.get_runtime_config()
            _old_dz = self.get_default_zone()

        _ipset_objs = []
        for _name in self.ipset.get_ipsets():
            _ipset_objs.append(self.ipset.get_ipset(_name))

        if not _panic:
            self.set_policy("DROP")

        # stop
        self.cleanup()

        start_exception = None
        try:
            self._start(reload=True, complete_reload=stop)
        except Exception as e:
            # save the exception for later, but continue restoring interfaces,
            # etc. We'll re-raise it at the end.
            start_exception = e

        # destroy ipsets no longer in the permanent configuration
        if flush_all:
            for obj in _ipset_objs:
                if not self.ipset.query_ipset(obj.name):
                    for backend in self.ipset.backends():
                        # nftables sets are part of the normal firewall ruleset.
                        if backend.name == "nftables":
                            continue
                        backend.set_destroy(obj.name)

        if not flush_all:
            # handle interfaces in the default zone and move them to the new
            # default zone if it changed
            _new_dz = self.get_default_zone()
            if _new_dz != _old_dz:
                # if_new_dz has been introduced with the reload, we need to add it
                # https://github.com/firewalld/firewalld/issues/53
                if _new_dz not in _zone_interfaces:
                    _zone_interfaces[_new_dz] = {}
                # default zone changed. Move interfaces from old default zone to
                # the new one.
                for iface, settings in list(_zone_interfaces[_old_dz].items()):
                    if settings["__default__"]:
                        # move only those that were added to default zone
                        # (not those that were added to specific zone same as
                        # default)
                        _zone_interfaces[_new_dz][iface] = \
                            _zone_interfaces[_old_dz][iface]
                        del _zone_interfaces[_old_dz][iface]

            # add interfaces to zones again
            for zone in self.zone.get_zones():
                if zone in _zone_interfaces:

                    for interface_id in _zone_interfaces[zone]:
                        self.zone.change_zone_of_interface(
                            zone, interface_id,
                            _zone_interfaces[zone][interface_id]["sender"])

                    del _zone_interfaces[zone]
                else:
                    log.info1("New zone '%s'.", zone)
            if len(_zone_interfaces) > 0:
                for zone in list(_zone_interfaces.keys()):
                    log.info1("Lost zone '%s', zone interfaces dropped.", zone)
                    del _zone_interfaces[zone]
            del _zone_interfaces

            # restore runtime-only ipsets
            for obj in _ipset_objs:
                if self.ipset.query_ipset(obj.name):
                    for entry in obj.entries:
                        try:
                            self.ipset.add_entry(obj.name, entry)
                        except FirewallError as msg:
                            if msg.code != errors.ALREADY_ENABLED:
                                raise msg
                else:
                    self.ipset.add_ipset(obj)
                    self.ipset.apply_ipset(obj.name)

            # restore direct config
            self.direct.set_config(_direct_config)

        # Restore permanent interfaces from NetworkManager
        nm_bus_name = nm_get_bus_name()
        if nm_bus_name:
            for zone in self.zone.get_zones() + [""]:
                for interface in nm_get_interfaces_in_zone(zone):
                    self.zone.change_zone_of_interface(zone,
                                                       interface,
                                                       sender=nm_bus_name)

        self._panic = _panic
        if not self._panic:
            self.set_policy("ACCEPT")

        if start_exception:
            self._state = "FAILED"
            raise start_exception
        else:
            self._state = "RUNNING"

    # STATE

    def get_state(self):
        return self._state

    # PANIC MODE

    def enable_panic_mode(self):
        if self._panic:
            raise FirewallError(errors.ALREADY_ENABLED,
                                "panic mode already enabled")

        try:
            self.set_policy("PANIC")
        except Exception as msg:
            raise FirewallError(errors.COMMAND_FAILED, msg)
        self._panic = True

    def disable_panic_mode(self):
        if not self._panic:
            raise FirewallError(errors.NOT_ENABLED,
                                "panic mode is not enabled")

        try:
            self.set_policy("ACCEPT")
        except Exception as msg:
            raise FirewallError(errors.COMMAND_FAILED, msg)
        self._panic = False

    def query_panic_mode(self):
        return self._panic

    # LOG DENIED

    def get_log_denied(self):
        return self._log_denied

    def set_log_denied(self, value):
        if value not in config.LOG_DENIED_VALUES:
            raise FirewallError(errors.INVALID_VALUE,
                                "'%s', choose from '%s'" % \
                                (value, "','".join(config.LOG_DENIED_VALUES)))

        if value != self.get_log_denied():
            self._log_denied = value
            self._firewalld_conf.set("LogDenied", value)
            self._firewalld_conf.write()
        else:
            raise FirewallError(errors.ALREADY_SET, value)

    # DEFAULT ZONE

    def get_default_zone(self):
        return self._default_zone

    def set_default_zone(self, zone):
        _zone = self.check_zone(zone)
        if _zone != self._default_zone:
            _old_dz = self._default_zone
            self._default_zone = _zone
            self._firewalld_conf.set("DefaultZone", _zone)
            self._firewalld_conf.write()

            # remove old default zone from ZONES and add new default zone
            self.zone.change_default_zone(_old_dz, _zone)

            # Move interfaces from old default zone to the new one.
            _old_dz_settings = self.zone.get_settings(_old_dz)
            for iface, settings in list(
                    _old_dz_settings["interfaces"].items()):
                if settings["__default__"]:
                    # move only those that were added to default zone
                    # (not those that were added to specific zone same as default)
                    self.zone.change_zone_of_interface("", iface)
        else:
            raise FirewallError(errors.ZONE_ALREADY_SET, _zone)

    def combine_runtime_with_permanent_settings(self, permanent, runtime):
        combined = permanent.copy()

        for key, value in runtime.items():
            # omit empty entries
            if value or isinstance(value, bool):
                combined[key] = value
            # make sure to remove values that were in permanent, but no
            # longer in runtime.
            elif key in combined:
                del combined[key]

        return combined

    def get_added_and_removed_settings(self, old_settings, new_settings):
        add_settings = {}
        remove_settings = {}
        for key in (set(old_settings.keys()) | set(new_settings.keys())):
            if key in new_settings:
                if isinstance(new_settings[key], list):
                    old = set(old_settings[key] if key in old_settings else [])
                    add_settings[key] = list(set(new_settings[key]) - old)
                    remove_settings[key] = list((old ^ set(new_settings[key]))
                                                & old)
                # check for bool or int because dbus.Boolean is a subclass of
                # int (because bool can't be subclassed).
                elif isinstance(new_settings[key], bool) or isinstance(
                        new_settings[key], int):
                    if not old_settings[key] and new_settings[key]:
                        add_settings[key] = True
                    elif old_settings[key] and not new_settings[key]:
                        remove_settings[key] = False
                else:
                    raise FirewallError(
                        errors.INVALID_SETTING,
                        "Unhandled setting type {} key {}".format(
                            type(new_settings[key]), key))

        return (add_settings, remove_settings)