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Filename : zone.py
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# -*- coding: utf-8 -*-
#
# Copyright (C) 2011-2016 Red Hat, Inc.
#
# Authors:
# Thomas Woerner <twoerner@redhat.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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/>.
#

__all__ = [ "Zone", "zone_reader", "zone_writer" ]

import xml.sax as sax
import os
import io
import shutil

from firewall import config
from firewall.functions import checkIPnMask, checkIP6nMask, checkInterface, uniqify, max_zone_name_len, check_mac
from firewall.core.base import DEFAULT_ZONE_TARGET, ZONE_TARGETS
from firewall.core.io.io_object import IO_Object, \
    IO_Object_ContentHandler, IO_Object_XMLGenerator
from firewall.core.io.policy import common_startElement, common_endElement, common_check_config, common_writer
from firewall.core import rich
from firewall.core.logger import log
from firewall import errors
from firewall.errors import FirewallError

class Zone(IO_Object):
    """ Zone class """

    IMPORT_EXPORT_STRUCTURE = (
        ( "version",  "" ),                            # s
        ( "short", "" ),                               # s
        ( "description", "" ),                         # s
        ( "UNUSED", False ),                           # b
        ( "target", "" ),                              # s
        ( "services", [ "", ], ),                      # as
        ( "ports", [ ( "", "" ), ], ),                 # a(ss)
        ( "icmp_blocks", [ "", ], ),                   # as
        ( "masquerade", False ),                       # b
        ( "forward_ports", [ ( "", "", "", "" ), ], ), # a(ssss)
        ( "interfaces", [ "" ] ),                      # as
        ( "sources", [ "" ] ),                         # as
        ( "rules_str", [ "" ] ),                       # as
        ( "protocols", [ "", ], ),                     # as
        ( "source_ports", [ ( "", "" ), ], ),          # a(ss)
        ( "icmp_block_inversion", False ),             # b
        ( "forward", True ),                           # b
    )
    ADDITIONAL_ALNUM_CHARS = [ "_", "-", "/" ]
    PARSER_REQUIRED_ELEMENT_ATTRS = {
        "short": None,
        "description": None,
        "zone": None,
        "service": [ "name" ],
        "port": [ "port", "protocol" ],
        "icmp-block": [ "name" ],
        "icmp-type": [ "name" ],
        "forward": None,
        "forward-port": [ "port", "protocol" ],
        "interface": [ "name" ],
        "rule": None,
        "source": None,
        "destination": None,
        "protocol": [ "value" ],
        "source-port": [ "port", "protocol" ],
        "log":  None,
        "nflog":  None,
        "audit": None,
        "accept": None,
        "reject": None,
        "drop": None,
        "mark": [ "set" ],
        "limit": [ "value" ],
        "icmp-block-inversion": None,
    }
    PARSER_OPTIONAL_ELEMENT_ATTRS = {
        "zone": [ "name", "immutable", "target", "version" ],
        "masquerade": [ "enabled" ],
        "forward-port": [ "to-port", "to-addr" ],
        "rule": [ "family", "priority" ],
        "source": [ "address", "mac", "invert", "family", "ipset" ],
        "destination": [ "address", "invert", "ipset" ],
        "log": [ "prefix", "level" ],
        "nflog": [ "group", "prefix", "queue-size" ],
        "reject": [ "type" ],
        "tcp-mss-clamp": [ "value" ],
    }

    @staticmethod
    def index_of(element):
        for i, (el, dummy) in enumerate(Zone.IMPORT_EXPORT_STRUCTURE):
            if el == element:
                return i
        raise FirewallError(errors.UNKNOWN_ERROR, "index_of()")

    def __init__(self):
        super(Zone, self).__init__()
        self.version = ""
        self.short = ""
        self.description = ""
        self.UNUSED = False
        self.target = DEFAULT_ZONE_TARGET
        self.services = [ ]
        self.ports = [ ]
        self.protocols = [ ]
        self.icmp_blocks = [ ]
        self.forward = True
        self.masquerade = False
        self.forward_ports = [ ]
        self.source_ports = [ ]
        self.interfaces = [ ]
        self.sources = [ ]
        self.rules = [ ]
        self.rules_str = [ ]
        self.icmp_block_inversion = False
        self.combined = False
        self.applied = False

    def cleanup(self):
        self.version = ""
        self.short = ""
        self.description = ""
        self.UNUSED = False
        self.target = DEFAULT_ZONE_TARGET
        del self.services[:]
        del self.ports[:]
        del self.protocols[:]
        del self.icmp_blocks[:]
        self.forward = True
        self.masquerade = False
        del self.forward_ports[:]
        del self.source_ports[:]
        del self.interfaces[:]
        del self.sources[:]
        del self.rules[:]
        del self.rules_str[:]
        self.icmp_block_inversion = False
        self.combined = False
        self.applied = False

    def __setattr__(self, name, value):
        if name == "rules_str":
            self.rules = [rich.Rich_Rule(rule_str=s) for s in value]
            # must convert back to string to get the canonical string.
            super(Zone, self).__setattr__(name, [str(s) for s in self.rules])
        else:
            super(Zone, self).__setattr__(name, value)

    def export_config_dict(self):
        conf = super(Zone, self).export_config_dict()
        del conf["UNUSED"]
        return conf

    def _check_config(self, config, item, all_config, all_io_objects):
        common_check_config(self, config, item, all_config, all_io_objects)

        if self.name in all_io_objects["policies"]:
            raise FirewallError(errors.NAME_CONFLICT, "Zone '{}': Can't have the same name as a policy.".format(self.name))

        if item == "target":
            if config not in ZONE_TARGETS:
                raise FirewallError(errors.INVALID_TARGET, "Zone '{}': invalid target '{}'".format(
                    self.name, config))
        elif item == "interfaces":
            for interface in config:
                if not checkInterface(interface):
                    raise FirewallError(errors.INVALID_INTERFACE, "Zone '{}': invalid interface '{}'".format(
                        self.name, interface))
                for zone in all_io_objects["zones"]:
                    if zone == self.name:
                        continue
                    if interface in all_io_objects["zones"][zone].interfaces:
                        raise FirewallError(errors.INVALID_INTERFACE,
                                "Zone '{}': interface '{}' already bound to zone '{}'".format(
                                    self.name, interface, zone))
        elif item == "sources":
            for source in config:
                if not checkIPnMask(source) and not checkIP6nMask(source) and \
                   not check_mac(source) and not source.startswith("ipset:"):
                    raise FirewallError(errors.INVALID_ADDR, "Zone '{}': invalid source '{}'".format(
                        self.name, source))
                for zone in all_io_objects["zones"]:
                    if zone == self.name:
                        continue
                    if source in all_io_objects["zones"][zone].sources:
                        raise FirewallError(errors.INVALID_ADDR,
                                "Zone '{}': source '{}' already bound to zone '{}'".format(
                                    self.name, source, zone))


    def check_name(self, name):
        super(Zone, self).check_name(name)
        if name.startswith('/'):
            raise FirewallError(errors.INVALID_NAME,
                                "Zone '{}': name can't start with '/'".format(name))
        elif name.endswith('/'):
            raise FirewallError(errors.INVALID_NAME,
                                "Zone '{}': name can't end with '/'".format(name))
        elif name.count('/') > 1:
            raise FirewallError(errors.INVALID_NAME,
                                "Zone '{}': name has more than one '/'".format(name))
        else:
            if "/" in name:
                checked_name = name[:name.find('/')]
            else:
                checked_name = name
            if len(checked_name) > max_zone_name_len():
                raise FirewallError(errors.INVALID_NAME,
                                    "Zone '{}': name has {} chars, max is {}".format(
                                        name, len(checked_name), max_zone_name_len()))

    def combine(self, zone):
        self.combined = True
        self.filename = None
        self.version = ""
        self.short = ""
        self.description = ""

        for interface in zone.interfaces:
            if interface not in self.interfaces:
                self.interfaces.append(interface)
        for source in zone.sources:
            if source not in self.sources:
                self.sources.append(source)
        for service in zone.services:
            if service not in self.services:
                self.services.append(service)
        for port in zone.ports:
            if port not in self.ports:
                self.ports.append(port)
        for proto in zone.protocols:
            if proto not in self.protocols:
                self.protocols.append(proto)
        for icmp in zone.icmp_blocks:
            if icmp not in self.icmp_blocks:
                self.icmp_blocks.append(icmp)
        if zone.forward:
            self.forward = True
        if zone.masquerade:
            self.masquerade = True
        for forward in zone.forward_ports:
            if forward not in self.forward_ports:
                self.forward_ports.append(forward)
        for port in zone.source_ports:
            if port not in self.source_ports:
                self.source_ports.append(port)
        for rule in zone.rules:
            self.rules.append(rule)
            self.rules_str.append(str(rule))
        if zone.icmp_block_inversion:
            self.icmp_block_inversion = True

# PARSER

class zone_ContentHandler(IO_Object_ContentHandler):
    def __init__(self, item):
        IO_Object_ContentHandler.__init__(self, item)
        self._rule = None
        self._rule_error = False
        self._limit_ok = None

    def startElement(self, name, attrs):
        IO_Object_ContentHandler.startElement(self, name, attrs)
        if self._rule_error:
            return

        self.item.parser_check_element_attrs(name, attrs)

        if common_startElement(self, name, attrs):
            return

        elif name == "zone":
            if "name" in attrs:
                log.warning("Ignoring deprecated attribute name='%s'",
                            attrs["name"])
            if "version" in attrs:
                self.item.version = attrs["version"]
            if "immutable" in attrs:
                log.warning("Ignoring deprecated attribute immutable='%s'",
                            attrs["immutable"])
            if "target" in attrs:
                target = attrs["target"]
                if target not in ZONE_TARGETS:
                    raise FirewallError(errors.INVALID_TARGET, target)
                if target != "" and target != DEFAULT_ZONE_TARGET:
                    self.item.target = target

        elif name == "forward":
            if self.item.forward:
                log.warning("Forward already set, ignoring.")
            else:
                self.item.forward = True

        elif name == "interface":
            if self._rule:
                log.warning('Invalid rule: interface use in rule.')
                self._rule_error = True
                return
            # zone bound to interface
            if "name" not in attrs:
                log.warning('Invalid interface: Name missing.')
                self._rule_error = True
                return
            if attrs["name"] not in self.item.interfaces:
                self.item.interfaces.append(attrs["name"])
            else:
                log.warning("Interface '%s' already set, ignoring.",
                            attrs["name"])

        elif name == "source":
            if self._rule:
                if self._rule.source:
                    log.warning("Invalid rule: More than one source in rule '%s', ignoring.",
                                str(self._rule))
                    self._rule_error = True
                    return
                invert = False
                if "invert" in attrs and \
                        attrs["invert"].lower() in [ "yes", "true" ]:
                    invert = True
                addr = mac = ipset = None
                if "address" in attrs:
                    addr = attrs["address"]
                if "mac" in attrs:
                    mac = attrs["mac"]
                if "ipset" in attrs:
                    ipset = attrs["ipset"]
                self._rule.source = rich.Rich_Source(addr, mac, ipset,
                                                     invert=invert)
                return
            # zone bound to source
            if "address" not in attrs and "ipset" not in attrs:
                log.warning('Invalid source: No address no ipset.')
                return
            if "address" in attrs and "ipset" in attrs:
                log.warning('Invalid source: Address and ipset.')
                return
            if "family" in attrs:
                log.warning("Ignoring deprecated attribute family='%s'",
                            attrs["family"])
            if "invert" in attrs:
                log.warning('Invalid source: Invertion not allowed here.')
                return
            if "address" in attrs:
                if not checkIPnMask(attrs["address"]) and \
                   not checkIP6nMask(attrs["address"]) and \
                   not check_mac(attrs["address"]):
                    raise FirewallError(errors.INVALID_ADDR, attrs["address"])
            if "ipset" in attrs:
                entry = "ipset:%s" % attrs["ipset"]
                if entry not in self.item.sources:
                    self.item.sources.append(entry)
                else:
                    log.warning("Source '%s' already set, ignoring.",
                                attrs["address"])
            if "address" in attrs:
                entry = attrs["address"]
                if entry not in self.item.sources:
                    self.item.sources.append(entry)
                else:
                    log.warning("Source '%s' already set, ignoring.",
                                attrs["address"])

        elif name == "icmp-block-inversion":
            if self.item.icmp_block_inversion:
                log.warning("Icmp-Block-Inversion already set, ignoring.")
            else:
                self.item.icmp_block_inversion = True

        else:
            log.warning("Unknown XML element '%s'", name)
            return

    def endElement(self, name):
        IO_Object_ContentHandler.endElement(self, name)

        common_endElement(self, name)

def zone_reader(filename, path, no_check_name=False):
    zone = Zone()
    if not filename.endswith(".xml"):
        raise FirewallError(errors.INVALID_NAME,
                            "'%s' is missing .xml suffix" % filename)
    zone.name = filename[:-4]
    if not no_check_name:
        zone.check_name(zone.name)
    zone.filename = filename
    zone.path = path
    zone.builtin = False if path.startswith(config.ETC_FIREWALLD) else True
    zone.default = zone.builtin
    # new Zone() objects default this to True, but if reading on disk
    # configuration we have to assume False, because the absence of
    # <forward> element indicates False. Presence indicates True.
    zone.forward = False
    handler = zone_ContentHandler(zone)
    parser = sax.make_parser()
    parser.setContentHandler(handler)
    name = "%s/%s" % (path, filename)
    with open(name, "rb") as f:
        source = sax.InputSource(None)
        source.setByteStream(f)
        try:
            parser.parse(source)
        except sax.SAXParseException as msg:
            raise FirewallError(errors.INVALID_ZONE,
                                "not a valid zone file: %s" % \
                                msg.getException())
    del handler
    del parser
    return zone

def zone_writer(zone, path=None):
    _path = path if path else zone.path

    if zone.filename:
        name = "%s/%s" % (_path, zone.filename)
    else:
        name = "%s/%s.xml" % (_path, zone.name)

    if os.path.exists(name):
        try:
            shutil.copy2(name, "%s.old" % name)
        except Exception as msg:
            log.error("Backup of file '%s' failed: %s", name, msg)

    dirpath = os.path.dirname(name)
    if dirpath.startswith(config.ETC_FIREWALLD) and not os.path.exists(dirpath):
        if not os.path.exists(config.ETC_FIREWALLD):
            os.mkdir(config.ETC_FIREWALLD, 0o750)
        os.mkdir(dirpath, 0o750)

    f = io.open(name, mode='wt', encoding='UTF-8')
    handler = IO_Object_XMLGenerator(f)
    handler.startDocument()

    # start zone element
    attrs = {}
    if zone.version and zone.version != "":
        attrs["version"] = zone.version
    if zone.target != DEFAULT_ZONE_TARGET:
        attrs["target"] = zone.target
    handler.startElement("zone", attrs)
    handler.ignorableWhitespace("\n")

    common_writer(zone, handler)

    # interfaces
    for interface in uniqify(zone.interfaces):
        handler.ignorableWhitespace("  ")
        handler.simpleElement("interface", { "name": interface })
        handler.ignorableWhitespace("\n")

    # source
    for source in uniqify(zone.sources):
        handler.ignorableWhitespace("  ")
        if "ipset:" in source:
            handler.simpleElement("source", { "ipset": source[6:] })
        else:
            handler.simpleElement("source", { "address": source })
        handler.ignorableWhitespace("\n")

    # icmp-block-inversion
    if zone.icmp_block_inversion:
        handler.ignorableWhitespace("  ")
        handler.simpleElement("icmp-block-inversion", { })
        handler.ignorableWhitespace("\n")

    # forward
    if zone.forward:
        handler.ignorableWhitespace("  ")
        handler.simpleElement("forward", { })
        handler.ignorableWhitespace("\n")

    # end zone element
    handler.endElement("zone")
    handler.ignorableWhitespace("\n")
    handler.endDocument()
    f.close()
    del handler