From 3578ea71627a1b77d42dda5b06da22cbe0dfb734 Mon Sep 17 00:00:00 2001 From: Piotr Bartman Date: Thu, 22 Feb 2024 00:55:09 +0100 Subject: [PATCH] q-dev: fix block device events To properly report attachments or detachments of block devices, the logic has been moved to the extension. As a bonus, the following issue is fix: https://github.com/QubesOS/qubes-issues/issues/4692 --- qubes/ext/block.py | 227 ++++++++++++++++++++++++++++++-------- templates/libvirt/xen.xml | 5 - 2 files changed, 184 insertions(+), 48 deletions(-) diff --git a/qubes/ext/block.py b/qubes/ext/block.py index 318d2a920..8622fb248 100644 --- a/qubes/ext/block.py +++ b/qubes/ext/block.py @@ -4,6 +4,7 @@ # # Copyright (C) 2017 Marek Marczykowski-Górecki # +# Copyright (C) 2024 Piotr Bartman-Szwarc # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public @@ -189,10 +190,41 @@ def parent_device(self) -> Optional[qubes.devices.Device]: self._interface_num = interface_num return self._parent + @property + def attachment(self) -> Optional['qubes.vm.BaseVM']: + """ + Warning: this property is time-consuming, do not run in loop! + """ + if not self.backend_domain.is_running(): + return None + for vm in self.backend_domain.app.domains: + if not vm.is_running(): + continue + if self._is_attached_to(vm): + return vm + + return None + + def _is_attached_to(self, vm): + xml_desc = lxml.etree.fromstring(vm.libvirt_domain.XMLDesc()) + + for disk in xml_desc.findall('devices/disk'): + info = _try_get_block_device_info(vm.app, disk) + if not info: + continue + backend_domain, ident = info + + if backend_domain.name != self.backend_domain.name: + continue + + if self.ident == ident: + return True + return False + @property def self_identity(self) -> str: """ - Get identification of device not related to port. + Get identification of a device not related to port. """ parent_identity = '' p = self.parent_device @@ -231,6 +263,32 @@ def _sanitize( ) +def _try_get_block_device_info(app, disk): + if disk.get('type') != 'block': + return None + dev_path_node = disk.find('source') + if dev_path_node is None: + return None + + backend_domain_node = disk.find('backenddomain') + if backend_domain_node is not None: + backend_domain = app.domains[ + backend_domain_node.get('name')] + else: + backend_domain = app.domains[0] + + dev_path = dev_path_node.get('dev') + + if dev_path.startswith('/dev/'): + ident = dev_path[len('/dev/'):] + else: + ident = dev_path + + ident = ident.replace('/', '_') + + return backend_domain, ident + + class BlockDeviceExtension(qubes.ext.Extension): def __init__(self): super().__init__() @@ -245,28 +303,62 @@ def on_domain_init_load(self, vm, event): # avoid building a cache on domain-init, as it isn't fully set yet, # and definitely isn't running yet current_devices = { - dev.ident: dev.attachment + dev.ident: dev.attachment # TODO load all attachments at once for dev in self.on_device_list_block(vm, None) } - self.devices_cache[vm.name] = current_devices + self.devices_cache[vm.name] = current_devices.copy() else: - self.devices_cache[vm.name] = {} + self.devices_cache[vm.name] = {}.copy() @qubes.ext.handler('domain-qdb-change:/qubes-block-devices') def on_qdb_change(self, vm, event, path): - """A change in QubesDB means a change in device list.""" + """A change in QubesDB means a change in a device list.""" # pylint: disable=unused-argument - vm.fire_event('device-list-change:block') - current_devices = dict((dev.ident, dev.attachment) - for dev in self.on_device_list_block(vm, None)) + if path is not None: + vm.fire_event('device-list-change:block') + device_attachments = self.get_device_attachments(vm) + current_devices = dict( + (dev.ident, device_attachments.get(dev.ident, None)) + for dev in self.on_device_list_block(vm, None)) + + added, attached, detached, removed = ( + self._compare_cache(vm, current_devices)) # send events about devices detached/attached outside by themselves - # (like device pulled out or manual qubes.USB qrexec call) + for dev_id, front_vm in detached.items(): + dev = BlockDevice(vm, dev_id) + asyncio.ensure_future(front_vm.fire_event_async( + 'device-detach:block', device=dev)) + for dev_id in removed: + device = BlockDevice(vm, dev_id) + vm.fire_event('device-removed:block', device=device) + for dev_id in added: + device = BlockDevice(vm, dev_id) + vm.fire_event('device-added:block', device=device) + for dev_ident, front_vm in attached.items(): + dev = BlockDevice(vm, dev_ident) + asyncio.ensure_future(front_vm.fire_event_async( + 'device-attach:block', device=dev, options={})) + + self.devices_cache[vm.name] = current_devices.copy() + + for front_vm in vm.app.domains: + if not front_vm.is_running(): + continue + for assignment in front_vm.devices['block'].get_assigned_devices(): + if (assignment.backend_domain == vm + and assignment.ident in added + and assignment.ident not in attached + ): + asyncio.ensure_future(self._attach_and_notify( + front_vm, assignment.device, assignment.options)) + + def _compare_cache(self, vm, current_devices): # compare cached devices and current devices, collect: # - newly appeared devices (ident) # - devices attached from a vm to frontend vm (ident: frontend_vm) # - devices detached from frontend vm (ident: frontend_vm) - # - disappeared devices, e.g. plugged out (ident) + # - disappeared devices, e.g., plugged out (ident) added = set() attached = dict() detached = dict() @@ -284,8 +376,8 @@ def on_qdb_change(self, vm, event, path): elif cached_front is None: attached[dev_id] = front_vm else: - # front changed from one to another, so we signal it as: - # detach from first one and attach to the second one. + # a front changed from one to another, so we signal it as: + # detach from the first one and attach to the second one. detached[dev_id] = cached_front attached[dev_id] = front_vm @@ -294,41 +386,33 @@ def on_qdb_change(self, vm, event, path): removed.add(dev_id) if cached_front is not None: detached[dev_id] = cached_front + return added, attached, detached, removed - for dev_id, front_vm in detached.items(): - dev = BlockDevice(vm, dev_id) - asyncio.ensure_future(front_vm.fire_event_async( - 'device-detach:block', device=dev)) - for dev_id in removed: - device = BlockDevice(vm, dev_id) - vm.fire_event('device-removed:block', device=device) - for dev_id in added: - device = BlockDevice(vm, dev_id) - vm.fire_event('device-added:block', device=device) - for dev_ident, front_vm in attached.items(): - dev = BlockDevice(vm, dev_ident) - asyncio.ensure_future(front_vm.fire_event_async( - 'device-attach:block', device=dev, options={})) + def get_device_attachments(self, vm_): + result = {} + for vm in vm_.app.domains: + if not vm.is_running(): + continue - self.devices_cache[vm.name] = current_devices + xml_desc = lxml.etree.fromstring(vm.libvirt_domain.XMLDesc()) - for front_vm in vm.app.domains: - if not front_vm.is_running(): - continue - for assignment in front_vm.devices['block'].get_assigned_devices(): - if (assignment.backend_domain == vm - and assignment.ident in added - and assignment.ident not in attached - ): - asyncio.ensure_future(self._attach_and_notify( - front_vm, assignment.device, assignment.options)) + for disk in xml_desc.findall('devices/disk'): + info = _try_get_block_device_info(vm.app, disk) + if not info: + continue + _backend_domain, ident = info + + result[ident] = vm + return result def device_get(self, vm, ident): - '''Read information about device from QubesDB + """ + Read information about a device from QubesDB :param vm: backend VM object :param ident: device identifier - :returns BlockDevice''' + :returns BlockDevice + """ untrusted_qubes_device_attrs = vm.untrusted_qdb.list( '/qubes-block-devices/{}/'.format(ident)) @@ -446,7 +530,7 @@ def on_device_pre_attached_block(self, vm, event, device, options): if isinstance(device, qubes.devices.UnknownDevice): print(f'{device.devclass.capitalize()} device {device} ' 'not available, skipping.', file=sys.stderr) - return + raise qubes.devices.UnrecognizedDevice() # validate options for option, value in options.items(): @@ -482,17 +566,34 @@ def on_device_pre_attached_block(self, vm, event, device, options): 'This device can be attached only read-only') if not vm.is_running(): + print("Not attach, not running", file=sys.stderr) + return + + if not isinstance(device, BlockDevice): + print("The device is not recognized as block device, " + f"skipping attachment of {device}", + file=sys.stderr) return + if device.attachment: + raise qubes.devices.DeviceAlreadyAttached( + 'Device {!s} already attached to {!s}'.format( + device, device.attachment) + ) + if not device.backend_domain.is_running(): - raise qubes.exc.QubesVMNotRunningError(device.backend_domain, - 'Domain {} needs to be running to attach device from ' - 'it'.format(device.backend_domain.name)) + raise qubes.exc.QubesVMNotRunningError( + device.backend_domain, + f'Domain {device.backend_domain.name} needs to be running ' + f'to attach device from it') + + self.devices_cache[device.backend_domain.name][device.ident] = vm if 'frontend-dev' not in options: options['frontend-dev'] = self.find_unused_frontend( vm, options.get('devtype', 'disk')) + print(f'attaching {device} exposed by {device.backend_domain.name}') vm.libvirt_domain.attachDevice( vm.app.env.get_template('libvirt/devices/block.xml').render( device=device, vm=vm, options=options)) @@ -514,6 +615,44 @@ async def _attach_and_notify(self, vm, device, options): await vm.fire_event_async( 'device-attach:block', device=device, options=options) + @qubes.ext.handler('domain-shutdown') + async def on_domain_shutdown(self, vm, event, **_kwargs): + """ + Remove from cache devices attached to or exposed by the vm. + """ + # pylint: disable=unused-argument + + new_cache = {} + for domain in vm.app.domains.values(): + new_cache[domain.name] = {} + if domain == vm: + for dev_id, front_vm in self.devices_cache[domain.name].items(): + if front_vm is None: + continue + dev = BlockDevice(vm, dev_id) + await self._detach_and_notify(vm, dev, options=None) + continue + for dev_id, front_vm in self.devices_cache[domain.name].items(): + if front_vm == vm: + dev = BlockDevice(vm, dev_id) + asyncio.ensure_future(front_vm.fire_event_async( + 'device-detach:block', device=dev)) + else: + new_cache[domain.name][dev_id] = front_vm + self.devices_cache = new_cache.copy() + + async def _detach_and_notify(self, vm, device, options): + # bypass DeviceCollection logic preventing double attach + self.on_device_pre_detached_block( + vm, 'device-pre-detach:block', device) + await vm.fire_event_async( + 'device-detach:block', device=device, options=options) + + @qubes.ext.handler('qubes-close', system=True) + def on_qubes_close(self, app, event): + # pylint: disable=unused-argument + self.devices_cache.clear() + @qubes.ext.handler('device-pre-detach:block') def on_device_pre_detached_block(self, vm, event, device): # pylint: disable=unused-argument @@ -524,6 +663,8 @@ def on_device_pre_detached_block(self, vm, event, device): # least) for attached_device, options in self.on_device_list_attached(vm, event): if attached_device == device: + self.devices_cache[device.backend_domain.name][ + device.ident] = None vm.libvirt_domain.detachDevice( vm.app.env.get_template('libvirt/devices/block.xml').render( device=device, vm=vm, options=options)) diff --git a/templates/libvirt/xen.xml b/templates/libvirt/xen.xml index 480a690c8..1156b839b 100644 --- a/templates/libvirt/xen.xml +++ b/templates/libvirt/xen.xml @@ -149,11 +149,6 @@ {# start external devices from xvdi #} {% set counter = {'i': 4} %} - {% for assignment in vm.devices.block.get_assigned_devices(True) %} - {% set device = assignment.device %} - {% set options = assignment.options %} - {% include 'libvirt/devices/block.xml' %} - {% endfor %} {% if vm.netvm %} {% include 'libvirt/devices/net.xml' with context %}