core-admin/qubes/vm/__init__.py

#!/usr/bin/python2 -O
# vim: fileencoding=utf-8

#
# The Qubes OS Project, https://www.qubes-os.org/
#
# Copyright (C) 2010-2015  Joanna Rutkowska <joanna@invisiblethingslab.com>
# Copyright (C) 2011-2015  Marek Marczykowski-Górecki
#                              <marmarek@invisiblethingslab.com>
# Copyright (C) 2014-2015  Wojtek Porczyk <woju@invisiblethingslab.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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

'''Qubes Virtual Machines

'''

import ast
import collections
import datetime
import functools
import itertools
import os
import re
import subprocess
import sys
import xml.parsers.expat

import lxml.etree

import qubes
import qubes.log
import qubes.events
import qubes.plugins
import qubes.tools.qvm_ls


class BaseVMMeta(qubes.plugins.Plugin, qubes.events.EmitterMeta):
    '''Metaclass for :py:class:`.BaseVM`'''
    def __init__(cls, name, bases, dict_):
        super(BaseVMMeta, cls).__init__(name, bases, dict_)
        qubes.tools.qvm_ls.process_class(cls)



class DeviceCollection(object):
    '''Bag for devices.

    Used as default value for :py:meth:`DeviceManager.__missing__` factory.

    :param vm: VM for which we manage devices
    :param class_: device class
    '''

    def __init__(self, vm, class_):
        self._vm = vm
        self._class = class_
        self._set = set()


    def attach(self, device):
        '''Attach (add) device to domain.

        :param str device: device identifier (format is class-dependent)
        '''

        if device in self:
            raise KeyError(
                'device {!r} of class {} already attached to {!r}'.format(
                    device, self._class, self._vm))
        self._vm.fire_event_pre('device-pre-attached:{}'.format(self._class),
            device)
        self._set.add(device)
        self._vm.fire_event('device-attached:{}'.format(self._class), device)


    def detach(self, device):
        '''Detach (remove) device from domain.

        :param str device: device identifier (format is class-dependent)
        '''

        if device not in self:
            raise KeyError(
                'device {!r} of class {} not attached to {!r}'.format(
                    device, self._class, self._vm))
        self._vm.fire_event_pre('device-pre-detached:{}'.format(self._class),
            device)
        self._set.remove(device)
        self._vm.fire_event('device-detached:{}'.format(self._class), device)


    def __iter__(self):
        return iter(self._set)


    def __contains__(self, item):
        return item in self._set


    def __len__(self):
        return len(self._set)


class DeviceManager(dict):
    '''Device manager that hold all devices by their classess.

    :param vm: VM for which we manage devices
    '''

    def __init__(self, vm):
        super(DeviceManager, self).__init__()
        self._vm = vm

    def __missing__(self, key):
        self[key] = DeviceCollection(self._vm, key)
        return self[key]


class BaseVM(qubes.PropertyHolder):
    '''Base class for all VMs

    :param app: Qubes application context
    :type app: :py:class:`qubes.Qubes`
    :param xml: xml node from which to deserialise
    :type xml: :py:class:`lxml.etree._Element` or :py:obj:`None`

    This class is responsible for serializing and deserialising machines and
    provides basic framework. It contains no management logic. For that, see
    :py:class:`qubes.vm.qubesvm.QubesVM`.
    '''
    # pylint: disable=no-member

    __metaclass__ = BaseVMMeta

    def __init__(self, app, xml, services=None, devices=None, tags=None,
            **kwargs):
        # pylint: disable=redefined-outer-name

        # self.app must be set before super().__init__, because some property
        # setters need working .app attribute
        #: mother :py:class:`qubes.Qubes` object
        self.app = app

        super(BaseVM, self).__init__(xml, **kwargs)

        #: dictionary of services that are run on this domain
        self.services = services or {}

        #: :py:class:`DeviceManager` object keeping devices that are attached to
        #: this domain
        self.devices = DeviceManager(self) if devices is None else devices

        #: user-specified tags
        self.tags = tags or {}

        if self.xml is not None:
            # services
            for node in xml.xpath('./services/service'):
                self.services[node.text] = bool(
                    ast.literal_eval(node.get('enabled', 'True').capitalize()))

            # devices (pci, usb, ...)
            for parent in xml.xpath('./devices'):
                devclass = parent.get('class')
                for node in parent.xpath('./device'):
                    self.devices[devclass].attach(node.text)

            # tags
            for node in xml.xpath('./tags/tag'):
                self.tags[node.get('name')] = node.text

            # TODO: firewall, policy

            # check if properties are appropriate
            all_names = set(prop.__name__ for prop in self.property_list())

            for node in self.xml.xpath('./properties/property'):
                name = node.get('name')
                if not name in all_names:
                    raise TypeError(
                        'property {!r} not applicable to {!r}'.format(
                            name, self.__class__.__name__))

        #: logger instance for logging messages related to this VM
        self.log = None

        if hasattr(self, 'name'):
            self.init_log()


    def init_log(self):
        '''Initialise logger for this domain.'''
        self.log = qubes.log.get_vm_logger(self.name)


    def __xml__(self):
        element = lxml.etree.Element('domain')
        element.set('id', 'domain-' + str(self.qid))
        element.set('class', self.__class__.__name__)

        element.append(self.xml_properties())

        services = lxml.etree.Element('services')
        for service in self.services:
            node = lxml.etree.Element('service')
            node.text = service
            if not self.services[service]:
                node.set('enabled', 'false')
            services.append(node)
        element.append(services)

        for devclass in self.devices:
            devices = lxml.etree.Element('devices')
            devices.set('class', devclass)
            for device in self.devices[devclass]:
                node = lxml.etree.Element('device')
                node.text = device
                devices.append(node)
            element.append(devices)

        tags = lxml.etree.Element('tags')
        for tag in self.tags:
            node = lxml.etree.Element('tag', name=tag)
            node.text = self.tags[tag]
            tags.append(node)
        element.append(tags)

        return element

    def __repr__(self):
        proprepr = []
        for prop in self.property_list():
            try:
                proprepr.append('{}={!r}'.format(
                    prop.__name__, getattr(self, prop.__name__)))
            except AttributeError:
                continue

        return '<{} object at {:#x} {}>'.format(
            self.__class__.__name__, id(self), ' '.join(proprepr))


    #
    # xml serialising methods
    #

    @staticmethod
    def lvxml_net_dev(ip, mac, backend):
        '''Return ``<interface>`` node for libvirt xml.

        This was previously _format_net_dev

        :param str ip: IP address of the frontend
        :param str mac: MAC (Ethernet) address of the frontend
        :param qubes.vm.qubesvm.QubesVM backend: Backend domain
        :rtype: lxml.etree._Element
        '''

        interface = lxml.etree.Element('interface', type='ethernet')
        interface.append(lxml.etree.Element('mac', address=mac))
        interface.append(lxml.etree.Element('ip', address=ip))
        interface.append(lxml.etree.Element('backenddomain', name=backend.name))
        interface.append(lxml.etree.Element('script', path="vif-route-qubes"))

        return interface


    @staticmethod
    def lvxml_pci_dev(address):
        '''Return ``<hostdev>`` node for libvirt xml.

        This was previously _format_pci_dev

        :param str ip: IP address of the frontend
        :param str mac: MAC (Ethernet) address of the frontend
        :param qubes.vm.qubesvm.QubesVM backend: Backend domain
        :rtype: lxml.etree._Element
        '''

        dev_match = re.match(r'([0-9a-f]+):([0-9a-f]+)\.([0-9a-f]+)', address)
        if not dev_match:
            raise ValueError('Invalid PCI device address: {!r}'.format(address))

        hostdev = lxml.etree.Element('hostdev', type='pci', managed='yes')
        source = lxml.etree.Element('source')
        source.append(lxml.etree.Element('address',
            bus='0x' + dev_match.group(1),
            slot='0x' + dev_match.group(2),
            function='0x' + dev_match.group(3)))
        hostdev.append(source)
        return hostdev

    #
    # old libvirt XML
    # TODO rewrite it to do proper XML synthesis via lxml.etree
    #

    def get_config_params(self):
        '''Return parameters for libvirt's XML domain config

        .. deprecated:: 3.0-alpha This will go away.
        '''

        args = {}
        args['name'] = self.name
        args['uuid'] = str(self.uuid)
        args['vmdir'] = self.dir_path
        args['pcidevs'] = ''.join(lxml.etree.tostring(self.lvxml_pci_dev(dev))
            for dev in self.devices['pci'])
        args['maxmem'] = str(self.maxmem)
        args['vcpus'] = str(self.vcpus)
        args['mem'] = str(min(self.memory, self.maxmem))

        if 'meminfo-writer' in self.services \
                and not self.services['meminfo-writer']:
            # If dynamic memory management disabled, set maxmem=mem
            args['maxmem'] = args['mem']

        if self.netvm is not None:
            args['ip'] = self.ip
            args['mac'] = self.mac
            args['gateway'] = self.netvm.gateway

            for i, addr in zip(itertools.count(start=1), self.dns):
                args['dns{}'.format(i)] = addr

            args['netmask'] = self.netmask
            args['netdev'] = lxml.etree.tostring(
                self.lvxml_net_dev(self.ip, self.mac, self.netvm))
            args['network_begin'] = ''
            args['network_end'] = ''
            args['no_network_begin'] = '<!--'
            args['no_network_end'] = '-->'
        else:
            args['ip'] = ''
            args['mac'] = ''
            args['gateway'] = ''
            args['dns1'] = ''
            args['dns2'] = ''
            args['netmask'] = ''
            args['netdev'] = ''
            args['network_begin'] = '<!--'
            args['network_end'] = '-->'
            args['no_network_begin'] = ''
            args['no_network_end'] = ''

        args.update(self.storage.get_config_params())

        if hasattr(self, 'kernelopts'):
            args['kernelopts'] = self.kernelopts
            if self.debug:
                self.log.info(
                    "Debug mode: adding 'earlyprintk=xen' to kernel opts")
                args['kernelopts'] += ' earlyprintk=xen'

        return args


    def create_config_file(self, file_path=None, prepare_dvm=False):
        '''Create libvirt's XML domain config file

        If :py:attr:`qubes.vm.qubesvm.QubesVM.uses_custom_config` is true, this
        does nothing.

        :param str file_path: Path to file to create \
            (default: :py:attr:`qubes.vm.qubesvm.QubesVM.conf_file`)
        :param bool prepare_dvm: If we are in the process of preparing \
            DisposableVM
        '''

        if file_path is None:
            file_path = self.conf_file
        if self.uses_custom_config:
            conf_appvm = open(file_path, "r")
            domain_config = conf_appvm.read()
            conf_appvm.close()
            return domain_config

        f_conf_template = open(self.config_file_template, 'r')
        conf_template = f_conf_template.read()
        f_conf_template.close()

        template_params = self.get_config_params()
        if prepare_dvm:
            template_params['name'] = '%NAME%'
            template_params['privatedev'] = ''
            template_params['netdev'] = re.sub(r"address='[0-9.]*'",
                "address='%IP%'", template_params['netdev'])
        domain_config = conf_template.format(**template_params)

        # FIXME: This is only for debugging purposes
        old_umask = os.umask(002)
        try:
            conf_appvm = open(file_path, "w")
            conf_appvm.write(domain_config)
            conf_appvm.close()
        except: # pylint: disable=bare-except
            # Ignore errors
            pass
        finally:
            os.umask(old_umask)

        return domain_config


    #
    # firewall
    # TODO rewrite it, have <firewall/> node under <domain/>
    # and possibly integrate with generic policy framework
    #

    def write_firewall_conf(self, conf):
        '''Write firewall config file.
        '''
        defaults = self.get_firewall_conf()
        expiring_rules_present = False
        for item in defaults.keys():
            if item not in conf:
                conf[item] = defaults[item]

        root = lxml.etree.Element(
                "QubesFirewallRules",
                policy=("allow" if conf["allow"] else "deny"),
                dns=("allow" if conf["allowDns"] else "deny"),
                icmp=("allow" if conf["allowIcmp"] else "deny"),
                yumProxy=("allow" if conf["allowYumProxy"] else "deny"))

        for rule in conf["rules"]:
            # For backward compatibility
            if "proto" not in rule:
                if rule["portBegin"] is not None and rule["portBegin"] > 0:
                    rule["proto"] = "tcp"
                else:
                    rule["proto"] = "any"
            element = lxml.etree.Element(
                    "rule",
                    address=rule["address"],
                    proto=str(rule["proto"]),
            )
            if rule["netmask"] is not None and rule["netmask"] != 32:
                element.set("netmask", str(rule["netmask"]))
            if rule.get("portBegin", None) is not None and \
                            rule["portBegin"] > 0:
                element.set("port", str(rule["portBegin"]))
            if rule.get("portEnd", None) is not None and rule["portEnd"] > 0:
                element.set("toport", str(rule["portEnd"]))
            if "expire" in rule:
                element.set("expire", str(rule["expire"]))
                expiring_rules_present = True

            root.append(element)

        tree = lxml.etree.ElementTree(root)

        try:
            old_umask = os.umask(002)
            with open(self.firewall_conf, 'w') as fd:
                tree.write(fd, encoding="UTF-8", pretty_print=True)
            fd.close()
            os.umask(old_umask)
        except EnvironmentError as err: # pylint: disable=broad-except
            print >> sys.stderr, "{0}: save error: {1}".format(
                    os.path.basename(sys.argv[0]), err)
            return False

        # Automatically enable/disable 'yum-proxy-setup' service based on
        # allowYumProxy
        if conf['allowYumProxy']:
            self.services['yum-proxy-setup'] = True
        else:
            if self.services.has_key('yum-proxy-setup'):
                self.services.pop('yum-proxy-setup')

        if expiring_rules_present:
            subprocess.call(["sudo", "systemctl", "start",
                             "qubes-reload-firewall@%s.timer" % self.name])

        return True

    def has_firewall(self):
        return os.path.exists(self.firewall_conf)

    @staticmethod
    def get_firewall_defaults():
        return {
            'rules': list(),
            'allow': True,
            'allowDns': True,
            'allowIcmp': True,
            'allowYumProxy': False}

    def get_firewall_conf(self):
        conf = self.get_firewall_defaults()

        try:
            tree = lxml.etree.parse(self.firewall_conf)
            root = tree.getroot()

            conf["allow"] = (root.get("policy") == "allow")
            conf["allowDns"] = (root.get("dns") == "allow")
            conf["allowIcmp"] = (root.get("icmp") == "allow")
            conf["allowYumProxy"] = (root.get("yumProxy") == "allow")

            for element in root:
                rule = {}
                attr_list = ("address", "netmask", "proto", "port", "toport",
                             "expire")

                for attribute in attr_list:
                    rule[attribute] = element.get(attribute)

                if rule["netmask"] is not None:
                    rule["netmask"] = int(rule["netmask"])
                else:
                    rule["netmask"] = 32

                if rule["port"] is not None:
                    rule["portBegin"] = int(rule["port"])
                else:
                    # backward compatibility
                    rule["portBegin"] = 0

                # For backward compatibility
                if rule["proto"] is None:
                    if rule["portBegin"] > 0:
                        rule["proto"] = "tcp"
                    else:
                        rule["proto"] = "any"

                if rule["toport"] is not None:
                    rule["portEnd"] = int(rule["toport"])
                else:
                    rule["portEnd"] = None

                if rule["expire"] is not None:
                    rule["expire"] = int(rule["expire"])
                    if rule["expire"] <= int(datetime.datetime.now().strftime(
                            "%s")):
                        continue
                else:
                    del rule["expire"]

                del rule["port"]
                del rule["toport"]

                conf["rules"].append(rule)

        except EnvironmentError as err: # pylint: disable=broad-except
            # problem accessing file, like ENOTFOUND, EPERM or sth
            # return default config
            return conf

        except (xml.parsers.expat.ExpatError,
                ValueError, LookupError) as err:
            # config is invalid
            print("{0}: load error: {1}".format(
                os.path.basename(sys.argv[0]), err))
            return None

        return conf


__all__ = ['BaseVMMeta', 'DeviceCollection', 'DeviceManager', 'BaseVM'] \
    + qubes.plugins.load(__file__)