#!/usr/bin/python2 -O # vim: fileencoding=utf-8 # # The Qubes OS Project, https://www.qubes-os.org/ # # Copyright (C) 2010-2015 Joanna Rutkowska # Copyright (C) 2011-2015 Marek Marczykowski-Górecki # # Copyright (C) 2014-2015 Wojtek Porczyk # # 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. # import collections import errno import functools import grp import logging import os import sys import tempfile import time import jinja2 import libvirt import lxml.etree try: import xen.lowlevel.xs import xen.lowlevel.xc except ImportError: pass if os.name == 'posix': import fcntl elif os.name == 'nt': # pylint: disable=import-error import win32con import win32file import pywintypes else: raise RuntimeError("Qubes works only on POSIX or WinNT systems") import qubes import qubes.ext import qubes.utils import qubes.vm.adminvm import qubes.vm.qubesvm import qubes.vm.templatevm class VirDomainWrapper(object): def __init__(self, connection, vm): self._connection = connection self._vm = vm def _reconnect_if_dead(self): is_dead = not self._vm.connect().isAlive() if is_dead: self._connection._reconnect_if_dead() self._vm = self._connection._conn.lookupByUUID(self._vm.getUUID()) return is_dead def __getattr__(self, attrname): attr = getattr(self._vm, attrname) if not isinstance(attr, collections.Callable): return attr @functools.wraps(attr) def wrapper(*args, **kwargs): try: return attr(*args, **kwargs) except libvirt.libvirtError as e: if self._reconnect_if_dead(): return getattr(self._vm, attrname)(*args, **kwargs) raise return wrapper class VirConnectWrapper(object): def __init__(self, uri): self._conn = libvirt.open(uri) def _reconnect_if_dead(self): is_dead = not self._conn.isAlive() if is_dead: self._conn = libvirt.open(self._conn.getURI()) return is_dead def _wrap_domain(self, ret): if isinstance(ret, libvirt.virDomain): ret = VirDomainWrapper(self, ret) return ret def __getattr__(self, attrname): attr = getattr(self._conn, attrname) if not isinstance(attr, collections.Callable): return attr @functools.wraps(attr) def wrapper(*args, **kwargs): try: return self._wrap_domain(attr(*args, **kwargs)) except libvirt.libvirtError as e: if self._reconnect_if_dead(): return self._wrap_domain( getattr(self._conn, attrname)(*args, **kwargs)) raise return wrapper class VMMConnection(object): '''Connection to Virtual Machine Manager (libvirt)''' def __init__(self): self._libvirt_conn = None self._xs = None self._xc = None self._offline_mode = False @property def offline_mode(self): '''Check or enable offline mode (do not actually connect to vmm)''' return self._offline_mode @offline_mode.setter def offline_mode(self, value): if value and self._libvirt_conn is not None: raise qubes.exc.QubesException( 'Cannot change offline mode while already connected') self._offline_mode = value def _libvirt_error_handler(self, ctx, error): pass def init_vmm_connection(self): '''Initialise connection This method is automatically called when getting''' if self._libvirt_conn is not None: # Already initialized return if self._offline_mode: # Do not initialize in offline mode raise qubes.exc.QubesException( 'VMM operations disabled in offline mode') if 'xen.lowlevel.xs' in sys.modules: self._xs = xen.lowlevel.xs.xs() if 'xen.lowlevel.cs' in sys.modules: self._xc = xen.lowlevel.xc.xc() self._libvirt_conn = VirConnectWrapper( qubes.config.defaults['libvirt_uri']) libvirt.registerErrorHandler(self._libvirt_error_handler, None) @property def libvirt_conn(self): '''Connection to libvirt''' self.init_vmm_connection() return self._libvirt_conn @property def xs(self): '''Connection to Xen Store This property in available only when running on Xen. ''' # XXX what about the case when we run under KVM, # but xen modules are importable? if 'xen.lowlevel.xs' not in sys.modules: raise AttributeError( 'xs object is available under Xen hypervisor only') self.init_vmm_connection() return self._xs @property def xc(self): '''Connection to Xen This property in available only when running on Xen. ''' # XXX what about the case when we run under KVM, # but xen modules are importable? if 'xen.lowlevel.xc' not in sys.modules: raise AttributeError( 'xc object is available under Xen hypervisor only') self.init_vmm_connection() return self._xs def __del__(self): if self._libvirt_conn: self._libvirt_conn.close() class QubesHost(object): '''Basic information about host machine :param qubes.Qubes app: Qubes application context (must have \ :py:attr:`Qubes.vmm` attribute defined) ''' def __init__(self, app): self.app = app self._no_cpus = None self._total_mem = None self._physinfo = None def _fetch(self): if self._no_cpus is not None: return # pylint: disable=unused-variable (model, memory, cpus, mhz, nodes, socket, cores, threads) = \ self.app.vmm.libvirt_conn.getInfo() self._total_mem = long(memory) * 1024 self._no_cpus = cpus self.app.log.debug('QubesHost: no_cpus={} memory_total={}'.format( self.no_cpus, self.memory_total)) try: self.app.log.debug('QubesHost: xen_free_memory={}'.format( self.get_free_xen_memory())) except NotImplementedError: pass @property def memory_total(self): '''Total memory, in kbytes''' self._fetch() return self._total_mem @property def no_cpus(self): '''Number of CPUs''' self._fetch() return self._no_cpus def get_free_xen_memory(self): '''Get free memory from Xen's physinfo. :raises NotImplementedError: when not under Xen ''' try: self._physinfo = self.app.xc.physinfo() except AttributeError: raise NotImplementedError('This function requires Xen hypervisor') return long(self._physinfo['free_memory']) def measure_cpu_usage(self, previous_time=None, previous=None, wait_time=1): '''Measure cpu usage for all domains at once. This function requires Xen hypervisor. .. versionchanged:: 3.0 argument order to match return tuple :raises NotImplementedError: when not under Xen ''' if previous is None: previous_time = time.time() previous = {} try: info = self.app.vmm.xc.domain_getinfo(0, qubes.config.max_qid) except AttributeError: raise NotImplementedError( 'This function requires Xen hypervisor') for vm in info: previous[vm['domid']] = {} previous[vm['domid']]['cpu_time'] = ( vm['cpu_time'] / vm['online_vcpus']) previous[vm['domid']]['cpu_usage'] = 0 time.sleep(wait_time) current_time = time.time() current = {} try: info = self.app.vmm.xc.domain_getinfo(0, qubes.config.max_qid) except AttributeError: raise NotImplementedError( 'This function requires Xen hypervisor') for vm in info: current[vm['domid']] = {} current[vm['domid']]['cpu_time'] = ( vm['cpu_time'] / max(vm['online_vcpus'], 1)) if vm['domid'] in previous.keys(): current[vm['domid']]['cpu_usage'] = ( float(current[vm['domid']]['cpu_time'] - previous[vm['domid']]['cpu_time']) / long(1000 ** 3) / (current_time - previous_time) * 100) if current[vm['domid']]['cpu_usage'] < 0: # VM has been rebooted current[vm['domid']]['cpu_usage'] = 0 else: current[vm['domid']]['cpu_usage'] = 0 return (current_time, current) class VMCollection(object): '''A collection of Qubes VMs VMCollection supports ``in`` operator. You may test for ``qid``, ``name`` and whole VM object's presence. Iterating over VMCollection will yield machine objects. ''' def __init__(self, app): self.app = app self._dict = dict() def __repr__(self): return '<{} {!r}>'.format( self.__class__.__name__, list(sorted(self.keys()))) def items(self): '''Iterate over ``(qid, vm)`` pairs''' for qid in self.qids(): yield (qid, self[qid]) def qids(self): '''Iterate over all qids qids are sorted by numerical order. ''' return iter(sorted(self._dict.keys())) keys = qids def names(self): '''Iterate over all names names are sorted by lexical order. ''' return iter(sorted(vm.name for vm in self._dict.values())) def vms(self): '''Iterate over all machines vms are sorted by qid. ''' return iter(sorted(self._dict.values())) __iter__ = vms values = vms def add(self, value): '''Add VM to collection :param qubes.vm.BaseVM value: VM to add :raises TypeError: when value is of wrong type :raises ValueError: when there is already VM which has equal ``qid`` ''' # this violates duck typing, but is needed # for VMProperty to function correctly if not isinstance(value, qubes.vm.BaseVM): raise TypeError('{} holds only BaseVM instances'.format( self.__class__.__name__)) if value.qid in self: raise ValueError('This collection already holds VM that has ' 'qid={!r} ({!r})'.format(value.qid, self[value.qid])) if value.name in self: raise ValueError('This collection already holds VM that has ' 'name={!r} ({!r})'.format(value.name, self[value.name])) self._dict[value.qid] = value value.events_enabled = True self.app.fire_event('domain-add', value) return value def __getitem__(self, key): if isinstance(key, int): return self._dict[key] if isinstance(key, basestring): for vm in self: if vm.name == key: return vm raise KeyError(key) if isinstance(key, qubes.vm.BaseVM): if key in self: return key raise KeyError(key) raise KeyError(key) def __delitem__(self, key): vm = self[key] self.app.fire_event_pre('domain-pre-delete', vm) del self._dict[vm.qid] self.app.fire_event('domain-delete', vm) def __contains__(self, key): return any((key == vm or key == vm.qid or key == vm.name) for vm in self) def __len__(self): return len(self._dict) def get_vms_based_on(self, template): template = self[template] return set(vm for vm in self if hasattr(vm, 'template') and vm.template == template) def get_vms_connected_to(self, netvm): new_vms = set([self[netvm]]) dependent_vms = set() # Dependency resolving only makes sense on NetVM (or derivative) # if not self[netvm_qid].is_netvm(): # return set([]) while len(new_vms) > 0: cur_vm = new_vms.pop() for vm in cur_vm.connected_vms: if vm in dependent_vms: continue dependent_vms.add(vm.qid) # if vm.is_netvm(): new_vms.add(vm.qid) return dependent_vms # XXX with Qubes Admin Api this will probably lead to race condition # whole process of creating and adding should be synchronised def get_new_unused_qid(self): used_ids = set(self.qids()) for i in range(1, qubes.config.max_qid): if i not in used_ids: return i raise LookupError("Cannot find unused qid!") def get_new_unused_netid(self): used_ids = set([vm.netid for vm in self]) # if vm.is_netvm()]) for i in range(1, qubes.config.max_netid): if i not in used_ids: return i raise LookupError("Cannot find unused netid!") class Qubes(qubes.PropertyHolder): '''Main Qubes application :param str store: path to ``qubes.xml`` The store is loaded in stages: 1. In the first stage there are loaded some basic features from store (currently labels). 2. In the second stage stubs for all VMs are loaded. They are filled with their basic properties, like ``qid`` and ``name``. 3. In the third stage all global properties are loaded. They often reference VMs, like default netvm, so they should be filled after loading VMs. 4. In the fourth stage all remaining VM properties are loaded. They also need all VMs loaded, because they represent dependencies between VMs like aforementioned netvm. 5. In the fifth stage there are some fixups to ensure sane system operation. This class emits following events: .. event:: domain-add (subject, event, vm) When domain is added. :param subject: Event emitter :param event: Event name (``'domain-add'``) :param vm: Domain object .. event:: domain-delete (subject, event, vm) When domain is deleted. VM still has reference to ``app`` object, but is not contained within VMCollection. :param subject: Event emitter :param event: Event name (``'domain-delete'``) :param vm: Domain object Methods and attributes: ''' default_netvm = qubes.VMProperty('default_netvm', load_stage=3, default=None, allow_none=True, doc='''Default NetVM for AppVMs. Initial state is `None`, which means that AppVMs are not connected to the Internet.''') default_fw_netvm = qubes.VMProperty('default_fw_netvm', load_stage=3, default=None, allow_none=True, doc='''Default NetVM for ProxyVMs. Initial state is `None`, which means that ProxyVMs (including FirewallVM) are not connected to the Internet.''') default_template = qubes.VMProperty('default_template', load_stage=3, vmclass=qubes.vm.templatevm.TemplateVM, doc='Default template for new AppVMs') updatevm = qubes.VMProperty('updatevm', load_stage=3, allow_none=True, doc='''Which VM to use as `yum` proxy for updating AdminVM and TemplateVMs''') clockvm = qubes.VMProperty('clockvm', load_stage=3, allow_none=True, doc='Which VM to use as NTP proxy for updating AdminVM') default_kernel = qubes.property('default_kernel', load_stage=3, doc='Which kernel to use when not overriden in VM') # TODO #1637 #892 check_updates_vm = qubes.property('check_updates_vm', type=bool, setter=qubes.property.bool, default=True, doc='check for updates inside qubes') def __init__(self, store=None, load=True, **kwargs): #: logger instance for logging global messages self.log = logging.getLogger('app') self._extensions = qubes.ext.get_extensions() #: collection of all VMs managed by this Qubes instance self.domains = VMCollection(self) #: collection of all available labels for VMs self.labels = {} #: collection of all pools self.pools = {} #: Connection to VMM self.vmm = VMMConnection() #: Information about host system self.host = QubesHost(self) if store is not None: self._store = store else: self._store = os.environ.get('QUBES_XML_PATH', os.path.join( qubes.config.system_path['qubes_base_dir'], qubes.config.system_path['qubes_store_filename'])) super(Qubes, self).__init__(xml=None, **kwargs) self.__load_timestamp = None #: jinja2 environment for libvirt XML templates self.env = jinja2.Environment( loader=jinja2.FileSystemLoader('/usr/share/qubes/templates'), undefined=jinja2.StrictUndefined) if load: self.load() self.events_enabled = True @property def store(self): return self._store def load(self): '''Open qubes.xml :throws EnvironmentError: failure on parsing store :throws xml.parsers.expat.ExpatError: failure on parsing store :raises lxml.etree.XMLSyntaxError: on syntax error in qubes.xml ''' try: fd = os.open(self._store, os.O_RDWR) # no O_CREAT except OSError as e: if e.errno != errno.ENOENT: raise raise qubes.exc.QubesException( 'Qubes XML store {!r} is missing; use qubes-create tool'.format( self._store)) fh = os.fdopen(fd, 'rb') if os.name == 'posix': fcntl.lockf(fh, fcntl.LOCK_EX) elif os.name == 'nt': # pylint: disable=protected-access win32file.LockFileEx( win32file._get_osfhandle(fh.fileno()), win32con.LOCKFILE_EXCLUSIVE_LOCK, 0, -0x10000, pywintypes.OVERLAPPED()) self.xml = lxml.etree.parse(fh) # stage 1: load labels and pools for node in self.xml.xpath('./labels/label'): label = qubes.Label.fromxml(node) self.labels[label.index] = label for node in self.xml.xpath('./pools/pool'): name = node.get('name') assert name, "Pool name '%s' is invalid " % name try: self.pools[name] = self._get_pool(**node.attrib) except qubes.exc.QubesException as e: self.log.error(e.message) # stage 2: load VMs for node in self.xml.xpath('./domains/domain'): # pylint: disable=no-member cls = self.get_vm_class(node.get('class')) vm = cls(self, node) vm.load_properties(load_stage=2) vm.init_log() self.domains.add(vm) if 0 not in self.domains: self.domains.add(qubes.vm.adminvm.AdminVM( self, None, qid=0, name='dom0')) # stage 3: load global properties self.load_properties(load_stage=3) # stage 4: fill all remaining VM properties for vm in self.domains: vm.load_properties(load_stage=4) # stage 5: misc fixups self.property_require('default_fw_netvm', allow_none=True) self.property_require('default_netvm', allow_none=True) self.property_require('default_template') self.property_require('clockvm', allow_none=True) self.property_require('updatevm', allow_none=True) # Disable ntpd in ClockVM - to not conflict with ntpdate (both are # using 123/udp port) if hasattr(self, 'clockvm') and self.clockvm is not None: if self.clockvm.features.get('services/ntpd', False): self.log.warning("VM set as clockvm ({!r}) has enabled 'ntpd' " "service! Expect failure when syncing time in dom0.".format( self.clockvm)) else: self.clockvm.features['services/ntpd'] = '' for vm in self.domains: vm.events_enabled = True vm.fire_event('domain-load') # get a file timestamp (before closing it - still holding the lock!), # to detect whether anyone else have modified it in the meantime self.__load_timestamp = os.path.getmtime(self._store) # intentionally do not call explicit unlock fh.close() del fh def __xml__(self): element = lxml.etree.Element('qubes') element.append(self.xml_labels()) pools_xml = lxml.etree.Element('pools') for pool in self.pools.values(): xml = pool.__xml__() if xml is not None: pools_xml.append(xml) element.append(pools_xml) element.append(self.xml_properties()) domains = lxml.etree.Element('domains') for vm in self.domains: domains.append(vm.__xml__()) element.append(domains) return element def save(self): '''Save all data to qubes.xml There are several problems with saving :file:`qubes.xml` which must be mitigated: - Running out of disk space. No space left should not result in empty file. This is done by writing to temporary file and then renaming. - Attempts to write two or more files concurrently. This is done by sophisticated locking. :throws EnvironmentError: failure on saving ''' while True: fd_old = os.open(self._store, os.O_RDWR | os.O_CREAT) if os.name == 'posix': fcntl.lockf(fd_old, fcntl.LOCK_EX) elif os.name == 'nt': # pylint: disable=protected-access overlapped = pywintypes.OVERLAPPED() win32file.LockFileEx( win32file._get_osfhandle(fd_old), win32con.LOCKFILE_EXCLUSIVE_LOCK, 0, -0x10000, overlapped) # While we were waiting for lock, someone could have unlink()ed (or # rename()d) our file out of the filesystem. We have to ensure we # got lock on something linked to filesystem. If not, try again. if os.fstat(fd_old) == os.stat(self._store): break else: os.close(fd_old) if self.__load_timestamp: current_file_timestamp = os.path.getmtime(self._store) if current_file_timestamp != self.__load_timestamp: os.close(fd_old) raise qubes.exc.QubesException( "Someone else modified qubes.xml in the meantime") fh_new = tempfile.NamedTemporaryFile(prefix=self._store, delete=False) lxml.etree.ElementTree(self.__xml__()).write( fh_new, encoding='utf-8', pretty_print=True) fh_new.flush() os.chmod(fh_new.name, 0660) os.chown(fh_new.name, -1, grp.getgrnam('qubes').gr_gid) os.rename(fh_new.name, self._store) # intentionally do not call explicit unlock to not unlock the file # before all buffers are flushed fh_new.close() # update stored mtime, in case of multiple save() calls without # loading qubes.xml again self.__load_timestamp = os.path.getmtime(self._store) os.close(fd_old) @classmethod def create_empty_store(cls, *args, **kwargs): self = cls(*args, load=False, **kwargs) self.labels = { 1: qubes.Label(1, '0xcc0000', 'red'), 2: qubes.Label(2, '0xf57900', 'orange'), 3: qubes.Label(3, '0xedd400', 'yellow'), 4: qubes.Label(4, '0x73d216', 'green'), 5: qubes.Label(5, '0x555753', 'gray'), 6: qubes.Label(6, '0x3465a4', 'blue'), 7: qubes.Label(7, '0x75507b', 'purple'), 8: qubes.Label(8, '0x000000', 'black'), } for name, config in qubes.config.defaults['pool_configs'].items(): self.pools[name] = self._get_pool(**config) self.domains.add( qubes.vm.adminvm.AdminVM(self, None, qid=0, name='dom0')) self.save() return self def xml_labels(self): '''Serialise labels :rtype: lxml.etree._Element ''' labels = lxml.etree.Element('labels') for label in sorted(self.labels.values(), key=lambda labl: labl.index): labels.append(label.__xml__()) return labels def get_vm_class(self, clsname): '''Find the class for a domain. Classess are registered as setuptools' entry points in ``qubes.vm`` group. Any package may supply their own classess. :param str clsname: name of the class :return type: class ''' try: return qubes.utils.get_entry_point_one('qubes.vm', clsname) except KeyError: raise qubes.exc.QubesException( 'no such VM class: {!r}'.format(clsname)) # don't catch TypeError def add_new_vm(self, cls, qid=None, **kwargs): '''Add new Virtual Machine to colletion ''' if qid is None: qid = self.domains.get_new_unused_qid() # handle default template; specifically allow template=None (do not # override it with default template) if 'template' not in kwargs and hasattr(cls, 'template'): kwargs['template'] = self.default_template return self.domains.add(cls(self, None, qid=qid, **kwargs)) def get_label(self, label): '''Get label as identified by index or name :throws KeyError: when label is not found ''' # first search for index, verbatim try: return self.labels[label] except KeyError: pass # then search for name for i in self.labels.values(): if i.name == label: return i # last call, if label is a number represented as str, search in indices try: return self.labels[int(label)] except (KeyError, ValueError): pass raise KeyError(label) def add_pool(self, **kwargs): """ Add a storage pool to config.""" name = kwargs['name'] assert name not in self.pools.keys(), \ "Pool named %s already exists" % name pool = self._get_pool(**kwargs) pool.setup() self.pools[name] = pool def remove_pool(self, name): """ Remove a storage pool from config file. """ try: pool = self.pools[name] del self.pools[name] pool.destroy() except KeyError: return def get_pool(self, name): ''' Returns a :py:class:`qubes.storage.Pool` instance ''' try: return self.pools[name] except KeyError: raise qubes.exc.QubesException('Unknown storage pool ' + name) def _get_pool(self, **kwargs): try: name = kwargs['name'] assert name, 'Name needs to be an non empty string' except KeyError: raise qubes.exc.QubesException('No pool name for pool') try: driver = kwargs['driver'] except KeyError: raise qubes.exc.QubesException('No driver specified for pool ' + name) try: klass = qubes.utils.get_entry_point_one( qubes.storage.STORAGE_ENTRY_POINT, driver) del kwargs['driver'] return klass(**kwargs) except KeyError: raise qubes.exc.QubesException('Driver %s for pool %s' % (driver, name)) @qubes.events.handler('domain-pre-delete') def on_domain_pre_deleted(self, event, vm): # pylint: disable=unused-argument if isinstance(vm, qubes.vm.templatevm.TemplateVM): appvms = self.domains.get_vms_based_on(vm) if appvms: raise qubes.exc.QubesException( 'Cannot remove template that has dependent AppVMs. ' 'Affected are: {}'.format(', '.join( vm.name for name in sorted(appvms)))) @qubes.events.handler('domain-delete') def on_domain_deleted(self, event, vm): # pylint: disable=unused-argument for propname in ( 'default_netvm', 'default_fw_netvm', 'clockvm', 'updatevm', 'default_template', ): try: if getattr(self, propname) == vm: delattr(self, propname) except AttributeError: pass @qubes.events.handler('property-pre-set:clockvm') def on_property_pre_set_clockvm(self, event, name, newvalue, oldvalue=None): # pylint: disable=unused-argument,no-self-use if newvalue is None: return if newvalue.features.get('services/ntpd', False): raise qubes.exc.QubesVMError(newvalue, 'Cannot set {!r} as {!r} since it has ntpd enabled.'.format( newvalue.name, name)) else: newvalue.features['services/ntpd'] = '' @qubes.events.handler( 'property-pre-set:default_netvm', 'property-pre-set:default_fw_netvm') def on_property_pre_set_default_netvm(self, event, name, newvalue, oldvalue=None): # pylint: disable=unused-argument,invalid-name if newvalue is not None and oldvalue is not None \ and oldvalue.is_running() and not newvalue.is_running() \ and self.domains.get_vms_connected_to(oldvalue): raise qubes.exc.QubesVMNotRunningError(newvalue, 'Cannot change {!r} to domain that ' 'is not running ({!r}).'.format(name, newvalue.name)) @qubes.events.handler('property-set:default_fw_netvm') def on_property_set_default_fw_netvm(self, event, name, newvalue, oldvalue=None): # pylint: disable=unused-argument,invalid-name for vm in self.domains: if not vm.provides_network and vm.property_is_default('netvm'): # fire property-del:netvm as it is responsible for resetting # netvm to it's default value vm.fire_event('property-del:netvm', 'netvm', newvalue, oldvalue) @qubes.events.handler('property-set:default_netvm') def on_property_set_default_netvm(self, event, name, newvalue, oldvalue=None): # pylint: disable=unused-argument for vm in self.domains: if vm.provides_network and vm.property_is_default('netvm'): # fire property-del:netvm as it is responsible for resetting # netvm to it's default value vm.fire_event('property-del:netvm', 'netvm', newvalue, oldvalue)