Merge "docs: Cleanup/revise Secure Boot docs"
This commit is contained in:
Zuul
Gerrit Code Review
commit
c31fea571b
|
|
@ -113,10 +113,76 @@ Additional references:
|
|||
UEFI secure boot mode
|
||||
=====================
|
||||
|
||||
Secure Boot is an interesting topic because exists at an intersection of
|
||||
hardware, security, vendors, and what you are willing to put in place to in
|
||||
terms of process, controls, or further mechanisms to enable processes and
|
||||
capabilities.
|
||||
|
||||
At a high level, Secure Boot is where an artifact such as an operating system
|
||||
kernel or Preboot eXecution Environment (PXE) binary is read by the UEFI
|
||||
firmware, and executed if the artifact is signed with a trusted key.
|
||||
Once a piece of code has been loaded and executed, it may read more bytecode
|
||||
in and verify additional signed artifacts which were signed utilizing
|
||||
different keys.
|
||||
|
||||
This is fundamentally how most Linux operating systems boot today. A ``shim``
|
||||
loader is signed by an authority, Microsoft, which is generally trusted by
|
||||
hardware vendors. The shim loader then loads a boot loader such as Grub, which
|
||||
then loads an operating system.
|
||||
|
||||
Underlying challenges
|
||||
---------------------
|
||||
|
||||
A major challenge for Secure Boot is the state of Preboot eXecution
|
||||
Environment binaries. Operating System distribution vendors tend not to
|
||||
request the authority with the general signing keys to sign these binary
|
||||
artifacts. The result of this, is that it is nearly impossible to network
|
||||
boot a machine which has Secure Boot enabled.
|
||||
|
||||
There are reports in the Open Source community that Microsoft has been willing
|
||||
to sign iPXE binaries, however the requirements are a bit steep for Open
|
||||
Source and largely means that Vendors would need to shoulder the burden for
|
||||
signed iPXE binaries to become common place. The iPXE developers provide
|
||||
further `details on their website <https://ipxe.org/appnote/etoken>`_,
|
||||
but it provides the details which solidify why we're unlikely to see
|
||||
a signed iPXE loader.
|
||||
|
||||
That is, unless, you sign iPXE yourself.
|
||||
|
||||
Which you can do, but you need to put in place your own key management
|
||||
infrastructure and teach the hardware to trust your signature, which is
|
||||
no simple feat in itself.
|
||||
|
||||
.. NOTE::
|
||||
The utility to manage keys in Linux on a local machine is `mokutil`,
|
||||
however it's modeled for manual invocation. One may be able to manage
|
||||
keys via Baseboard Management Controller, and Ironic may add such
|
||||
capabilities at some point in time.
|
||||
|
||||
There is a possibility of utilizing
|
||||
`shim <https://wiki.debian.org/SecureBoot#Shim>`_ and Grub2 to network boot
|
||||
a machine, however Grub2's capabilities for booting a machine are extremely
|
||||
limited when compared to a tool like iPXE. It is also worth noting the bulk
|
||||
of Ironic's example configurations utilize iPXE, including whole activities
|
||||
like unmanaged hardware introspection with ironic-inspector.
|
||||
|
||||
For extra context, unmanaged introspection is when you ask ironic-inspector
|
||||
to inspect a machine *instead* of asking ironic. In other words, using
|
||||
``openstack baremetal introspection start <node>`` versus
|
||||
``baremetal node inspect <node>`` commands. This does require the
|
||||
``[inspector]require_managed_boot`` setting be set to ``true``.
|
||||
|
||||
Driver support for Deployment with Secure Boot
|
||||
----------------------------------------------
|
||||
|
||||
Some hardware types support turning `UEFI secure boot`_ dynamically when
|
||||
deploying an instance. Currently these are :doc:`/admin/drivers/ilo`,
|
||||
:doc:`/admin/drivers/irmc` and :doc:`/admin/drivers/redfish`.
|
||||
|
||||
Other drivers, such as :doc:`/admin/drivers/ipmitool`, may be able to be manually
|
||||
configured on the host, but as there is not standardization of Secure Boot
|
||||
support in the IPMI protocol, you may encounter unexpected behavior.
|
||||
|
||||
Support for the UEFI secure boot is declared by adding the ``secure_boot``
|
||||
capability in the ``capabilities`` parameter in the ``properties`` field of
|
||||
a node. ``secure_boot`` is a boolean parameter and takes value as ``true`` or
|
||||
|
|
@ -136,18 +202,54 @@ the secure boot capability.
|
|||
Compatible images
|
||||
-----------------
|
||||
|
||||
Use element ``ubuntu-signed`` or ``fedora`` to build signed deploy ISO and
|
||||
user images with `diskimage-builder
|
||||
<https://pypi.org/project/diskimage-builder>`_.
|
||||
Most mainstream and vendor backed Linux based public cloud images are already
|
||||
compatible with use of secure boot.
|
||||
|
||||
The below command creates files named cloud-image-boot.iso, cloud-image.initrd,
|
||||
cloud-image.vmlinuz and cloud-image.qcow2 in the current working directory::
|
||||
Using Shim and Grub2 for Secure Boot
|
||||
------------------------------------
|
||||
|
||||
cd <path-to-diskimage-builder>
|
||||
./bin/disk-image-create -o cloud-image ubuntu-signed baremetal iso
|
||||
To utilize Shim and Grub to boot a baremetal node, actions are required
|
||||
by the administrator of the Ironic deployment as well as the user of
|
||||
Ironic's API.
|
||||
|
||||
Ensure the public key of the signed image is loaded into bare metal to deploy
|
||||
signed images.
|
||||
For the Ironic Administrator
|
||||
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
To enable use of grub to network boot baremetal nodes for activities such
|
||||
as managed introspection, node cleaning, and deployment, some configuration
|
||||
is required in ironic.conf.::
|
||||
|
||||
[DEFAULT]
|
||||
enabled_boot_interfaces = pxe
|
||||
[pxe]
|
||||
uefi_pxe_config_template = $pybasedir/drivers/modules/pxe_grub_config.template
|
||||
tftp_root = /tftpboot
|
||||
loader_file_paths = bootx64.efi:/usr/lib/shimx64.efi.signed,grubx64.efi:/usr/lib/grub/x86_64-efi-signed/grubnetx64.efi.signed
|
||||
|
||||
.. NOTE::
|
||||
You may want to leverage the ``[pxe]loader_file_paths`` feature, which
|
||||
automatically copies boot loaders into the ``tftp_root`` folder, but this
|
||||
functionality is not required if you manually copy the named files into
|
||||
the Preboot eXecution Environment folder(s), by default the [pxe]tftp_root,
|
||||
and [deploy]http_root folders.
|
||||
|
||||
.. WARNING::
|
||||
Shim/Grub artifact paths will vary by distribution. The example above is
|
||||
taken from Ironic's Continuous Integration test jobs where this
|
||||
functionality is exercised.
|
||||
|
||||
For the Ironic user
|
||||
~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
To set a node to utilize the ``pxe`` boot_interface, execute the baremetal
|
||||
command::
|
||||
|
||||
baremetal node set --boot-interface pxe <node>
|
||||
|
||||
Alternatively, if your hardware supports HttpBoot and your Ironic is at
|
||||
least 2023.2, you can set the ``http`` boot_interface instead::
|
||||
|
||||
baremetal node set --boot-interface http <node>
|
||||
|
||||
Enabling with OpenStack Compute
|
||||
-------------------------------
|
||||
|
|
@ -177,12 +279,15 @@ Enabling standalone
|
|||
-------------------
|
||||
|
||||
To request secure boot for an instance in standalone mode (without OpenStack
|
||||
Compute), you need to add the capability directly to the node's
|
||||
``instance_info``::
|
||||
Compute), you must explicitly inform Ironic::
|
||||
|
||||
baremetal node set <node> --instance-info capabilities='{"secure_boot": "true"}'
|
||||
baremetal node set secure boot on <node>
|
||||
|
||||
.. _UEFI secure boot: https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#Secure_boot
|
||||
Which can also be disabled by exeuting negative form of the command::
|
||||
|
||||
baremetal node set secure boot off <node>
|
||||
|
||||
.. _UEFI secure boot: https://en.wikipedia.org/wiki/UEFI#Secure_Boot
|
||||
|
||||
Other considerations
|
||||
====================
|
||||
|
|
|
|||
Loading…
Reference in New Issue