[qubes-users] 'locking' a vm possible? (to prevent accidental shutdown)

Boryeu_Mao · April 14, 2024, 6:54pm

An attempt to shutdown sys-firewall in Qube Manager receive a warning about running processes in the qube; similarly on command line qvm-shutdown sys-firewall fails with an error. Is it possible to designate an appVM to behave similarly so it won’t get shutdown accidentally?

rustybird · April 15, 2024, 2:54pm

Boryeu Mao:

An attempt to shutdown `sys-firewall` in `Qube Manager` receive a warning
about running processes in the qube; similarly on command line
`qvm-shutdown sys-firewall` fails with an error. Is it possible to
designate an appVM to behave similarly so it won't get shutdown
accidentally?

Not as a user-facing feature AFAIK. But you could use the qubes.ext
Python entry point

github.com

QubesOS/qubes-core-admin/blob/v4.2.21/qubes/ext/init.py#L57-L59


      
          def get_extensions():
              return set(ext.load()()
                  for ext in pkg_resources.iter_entry_points('qubes.ext'))

to add another "domain-pre-shutdown" event handler like this one
(yours could e.g. check if the VM has a certain tag):

github.com

QubesOS/qubes-core-admin/blob/v4.2.21/qubes/ext/audio.py#L65-L75


      
          @qubes.ext.handler('domain-qdb-create')
          def on_domain_qdb_create(self, vm, event):
              # Add AudioVM Xen ID for gui-agent
              if getattr(vm, 'audiovm', None):
                  if vm != vm.audiovm and vm.audiovm.is_running():
                      vm.untrusted_qdb.write('/qubes-audio-domain-xid',
                                             str(vm.audiovm.xid))
          
          @qubes.ext.handler('property-set:default_audiovm', system=True)
          def on_property_set_default_audiovm(self, app, event, name, newvalue,
                                              oldvalue=None):

Rusty

rustybird · April 15, 2024, 3:00pm

Rusty Bird:

Boryeu Mao:
> An attempt to shutdown `sys-firewall` in `Qube Manager` receive a warning
> about running processes in the qube; similarly on command line
> `qvm-shutdown sys-firewall` fails with an error. Is it possible to
> designate an appVM to behave similarly so it won't get shutdown
> accidentally?

Not as a user-facing feature AFAIK. But you could use the qubes.ext
Python entry point

qubes-core-admin/qubes/ext/__init__.py at v4.2.21 · QubesOS/qubes-core-admin · GitHub

to add another "domain-pre-shutdown" event handler like this one
(yours could e.g. check if the VM has a certain tag):

qubes-core-admin/qubes/ext/audio.py at v4.2.21 · QubesOS/qubes-core-admin · GitHub

Sorry, that second link should have been:

github.com

QubesOS/qubes-core-admin/blob/v4.2.21/qubes/ext/audio.py#L31-L38


      
          @qubes.ext.handler('domain-pre-shutdown')
          def on_domain_pre_shutdown(self, vm, event, **kwargs):
              attached_vms = [domain for domain in self.attached_vms(vm) if
                              domain.is_running()]
              if attached_vms and not kwargs.get('force', False):
                  raise qubes.exc.QubesVMError(
                      self, 'There are running VMs using this VM as AudioVM: '
                            '{}'.format(', '.join(vm.name for vm in attached_vms)))

Rusty

Boryeu_Mao · April 16, 2024, 9:54pm

Thank you very much for the help. Time for a crash course on qubes-core-admin.