Using QID for DispVM ID was a bad idea in terms of anonymity:
1. It gives some clue about VMs count in the system. In case of large
numbers, this can be quite unique.
2. If new DispVM is started just after closing previous one, it will get
the same ID, and in consequence the same IP. In case of using TorVM,
this leads to use the same circuit as just closed DispVM.
Fixesqubesos/qubes-issues#983
At least to have there info about its backup.
This was already done in commit
dc6fd3c8f3, but later was erroneously
reverted during migration to libvirt.
Fixesqubesos/qubes-issues#958
This can happen when initially there was no default netvm, some domain
was started, then default netvm was set and started - then
netvm.connected_vms will contain domains which aren't really connected
there.
Especially this was happening in firstboot.
Otherwise it would point at the same object and for example changing
vm.services[] in one VM will change that also for another. That link
will be severed after reloading the VMs from qubes.xml, but at least in
case of DispVM startup its too late - vm.service['qubes-dvm'] is set for
the DispVM template even during normal startup, not savefile preparation.
This allows to specify tight network isolation for a VM, and finally
close one remaining way for leaking traffic around TorVM. Now when VM is
connected to for example TorVM, its DispVMs will be also connected
there.
The new property can be set to:
- default (uses_default_dispvm_netvm=True) - use the same NetVM/ProxyVM as the
calling VM itself - including none it that's the case
- None - DispVMs will be network-isolated
- some NetVM/ProxyVM - will be used, even if calling VM is network-isolated
Closesqubesos/qubes-issues#862
Define it only when really needed:
- during VM creation - to generate UUID
- just before VM startup
As a consequence we must handle possible exception when accessing
vm.libvirt_domain. It would be a good idea to make this field private in
the future. It isn't possible for now because block_* are external for
QubesVm class.
This hopefully fixes race condition when Qubes Manager tries to access
libvirt_domain (using some QubesVm.*) at the same time as other tool is
removing the domain. Additionally if Qubes Manage would loose that race, it could
define the domain again leaving some unused libvirt domain (blocking
that domain name for future use).
Provide vm.refresh(), which will force to reconnect do QubesDB daemon,
and also get new libvirt object (including new ID, if any). Use this
method whenever QubesDB call returns DisconnectedError exception. Also
raise that exception when someone is trying to talk to not running
QubesDB - instead of returning None.
Libvirt will replace domain XML when trying to define the new one with
the same name and UUID - this is exactly what we need. This fixes race
condition with other processes (especially Qubes Manager), which can try
to access that libvirt domain object at the same time.
It have nothing to do with xenstore, so change the name to not mislead.
Also get rid of unused "xid" parameter - we should use XID as little as
possible, because it is not a simple task to keep it current.
It is used by just started DispVM to notice when restore process
completed. Alternatively it could watch its own domid, but lets do it in
Xen-independent way.
When VM is started by root, config file is created with root owner and
user has no write access to it. As the directory is user-writable,
delete the file first.
Conflicts:
core-modules/000QubesVm.py
Do not load qubes.xml again, it can cause race conditions between two
instances of the same VM objects.
Especially when VM is starting ProxyVM to which it is connected,
firewall rules could not be loaded.
Long time ago passio=True was used to replace current process with
qrexec-client directly (qvm-run --pass-io was the called), but this
behaviour is not used anymore (qvm-run was the only user). And this
option was left untouched, with misleading name - one would assume that
using passio=False should disallow any I/O, but this isn't the case.
Especially qvm-sync-clock is calling clockvm.run('...', wait=True),
default value for passio=False. This causes to output data from
untrusted VM, without sanitising terminal sequences, which can be fatal.
This patch changes passio semantic to actually do what it means - when
set to True - VM process will be able to interact with
stdin/stdout/stderr. But when set to False, all those FDs will be
connected to /dev/null.
Conflicts:
core-modules/000QubesVm.py
Otherwise deadlock could happen - the script will try to get read lock
on qubes.xml, while the calling tool can already hold the lock. If that
was write lock (which is in case of qfile-daemon-dvm), the deadlock
occurs.
This is the only place where ID was used - all other places uses name.
Linux qrexec-client accepts both ID and name, but sticking to one option
will simplify things (especially Windows qrexec-client/daemon).
