2022-06-22 10:08:04 +00:00
|
|
|
===========
|
|
|
|
|
Secure Boot
|
|
|
|
|
===========
|
|
|
|
|
|
|
|
|
|
.. contents::
|
|
|
|
|
|
|
|
|
|
Quick configuration
|
|
|
|
|
===================
|
|
|
|
|
|
|
|
|
|
If you have libvirt 8.6.0 or newer, when creating a new VM you can
|
|
|
|
|
ask for Secure Boot to be enabled with
|
|
|
|
|
|
|
|
|
|
::
|
|
|
|
|
|
|
|
|
|
<os firmware='efi'>
|
|
|
|
|
<firmware>
|
|
|
|
|
<feature enabled='yes' name='enrolled-keys'/>
|
|
|
|
|
</firmware>
|
|
|
|
|
</os>
|
|
|
|
|
|
|
|
|
|
and for it to be disabled with
|
|
|
|
|
|
|
|
|
|
::
|
|
|
|
|
|
|
|
|
|
<os firmware='efi'>
|
|
|
|
|
<firmware>
|
|
|
|
|
<feature enabled='no' name='enrolled-keys'/>
|
|
|
|
|
</firmware>
|
|
|
|
|
</os>
|
|
|
|
|
|
|
|
|
|
These configuration will cause unsigned guest operating systems to
|
|
|
|
|
be rejected and allowed respectively.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Older libvirt versions
|
|
|
|
|
======================
|
|
|
|
|
|
|
|
|
|
If your libvirt version is older than 8.6.0 but newer than 7.2.0,
|
|
|
|
|
then enabling Secure Boot requires a slightly more verbose XML
|
|
|
|
|
snippet:
|
|
|
|
|
|
|
|
|
|
::
|
|
|
|
|
|
|
|
|
|
<os firmware='efi'>
|
|
|
|
|
<loader secure='yes'/>
|
|
|
|
|
<firmware>
|
|
|
|
|
<feature enabled='yes' name='enrolled-keys'/>
|
|
|
|
|
</firmware>
|
|
|
|
|
</os>
|
|
|
|
|
|
|
|
|
|
Versions older than 7.2.0 require manually providing all information
|
2022-07-04 08:07:47 +00:00
|
|
|
about the firmware and are not covered here. Please refer to `the
|
2022-06-22 10:08:04 +00:00
|
|
|
relevant documentation
|
|
|
|
|
<../formatdomain.html#operating-system-booting>`__ for details.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Changing an existing VM
|
|
|
|
|
=======================
|
|
|
|
|
|
|
|
|
|
Once the VM has been created, updating the XML configuration as
|
|
|
|
|
described above is **not** enough to change the Secure Boot status:
|
|
|
|
|
the NVRAM file associated with the VM has to be regenerated from its
|
|
|
|
|
template as well.
|
|
|
|
|
|
|
|
|
|
In order to do that, update the XML and then start the VM with
|
|
|
|
|
|
|
|
|
|
::
|
|
|
|
|
|
|
|
|
|
$ virsh start $vm --reset-nvram
|
|
|
|
|
|
|
|
|
|
This option is only available starting with libvirt 8.1.0, so if your
|
|
|
|
|
version of libvirt is older than that you will have to delete the
|
|
|
|
|
NVRAM file manually before starting the VM.
|
|
|
|
|
|
|
|
|
|
Most guest operating systems will be able to cope with the NVRAM file
|
|
|
|
|
being reinitialized, but in some cases the VM will be unable to boot
|
|
|
|
|
after the change.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Additional information
|
|
|
|
|
======================
|
|
|
|
|
|
|
|
|
|
There are two parts to enabling Secure Boot: the firmware supporting
|
|
|
|
|
the feature, and it being active.
|
|
|
|
|
|
|
|
|
|
Most host operating systems ship a build of EDKII (the open source
|
|
|
|
|
EFI implementation used for QEMU VMs) that supports the Secure Boot
|
|
|
|
|
feature, but simply using such a build will not result in unsigned
|
|
|
|
|
guest operating systems being rejected: for that to happen, keys that
|
|
|
|
|
can be used to validate the operating system signature need to be
|
|
|
|
|
provided as well.
|
|
|
|
|
|
|
|
|
|
Asking for the ``enrolled-keys`` firmware feature to be enabled will
|
|
|
|
|
cause libvirt to initialize the NVRAM file associated with the VM
|
|
|
|
|
from a template that contains a suitable set of keys. These keys
|
|
|
|
|
being present will cause the firmware to enforce the Secure Boot
|
|
|
|
|
signing requirements.
|
|
|
|
|
|
|
|
|
|
The opposite configuration, where the feature is explicitly disabled,
|
|
|
|
|
will result in no keys being present in the NVRAM file. Unable to
|
|
|
|
|
verify signatures, the firmware will allow even unsigned operating
|
|
|
|
|
systems to run.
|
