UEFI Secure Boot support for iLO drivers

https://blueprints.launchpad.net/ironic/+spec/uefi-secure-boot

Some of the Ironic deploy drivers support UEFI boot. It would be useful to security sensitive users to deploy more securely using Secure Boot feature of the UEFI. This spec proposes alternatives to support Secure Boot in baremetal provisioning for iLO drivers.

Problem description

Secure Boot is part of the UEFI specification (http://www.uefi.org). It helps to make sure that node boots using only software that is trusted by Admin/End user.

Secure Boot is different from TPM (Trusted Platform Module). TPM is a standard for a secure cryptoprocessor, which is dedicated microprocessor designed to secure hardware by integrating cryptographic keys into devices. Secure Boot is part of UEFI specification, which can secure the boot process by preventing the loading of drivers or OS loaders that are not signed with an acceptable digital signature.

When the node starts with secure boot enabled, system firmware checks the signature of each piece of boot software, including firmware drivers (Option ROMs), boot loaders and the operating system. If the signatures are good, the node boots, and the firmware gives control to the operating system.

The Admin and End users having security sensitivity with respect to baremetal provisioning owing to the workloads they intend to run on the provisioned nodes would be interested in using secure boot provided by UEFI.

Once secure boot is enabled for a node, it cannot boot using unsigned boot images. Hence it is important to use signed bootloaders and kernel if node were to be booted using secure boot.

Proposed change

Preparing the environment

  • The operator informs the Ironic using the capabilities property of the node. The operator may add a new capability secure_boot=True in capabilities within properties of that node. This is an optional property that can be used if node needs to be provisioned for secure boot. By default the behavior would be as if this property is set to False. The iLO hardware discovery feature (proposed) could auto discover the secure boot capability of the node and create node capability into that node object in future.
  • If the user has secure_boot capability set in the flavor, iLO drivers have ability to change the boot mode to UEFI and prepare the node for the secure boot on the fly using proliantutil library calls.

Preparing flavor for secure boot

  • The extra_specs field in the nova flavor should be used to indicate secure boot. User will need to create a flavor by adding “capabilities:secure_boot=”True” to it.
  • iLO driver will not do secure boot if “secure_boot” capability flavor is not present or set to “False”. Nova scheduler will use secure_boot capability as one of the node selection criteria if “secure_boot” is present in extra_spec. If “secure_boot” is not present in extra_spec then Nova scheduler will not consider “secure_boot” capability as a node selection criteria.
  • Ironic virt Driver needs to pass the flavor capability information to the driver as part of instance info. Having capability information as part of instance info would help driver in preparing and decommissioning the node appropriately. With respect to secure boot feature, instance info should contain the capability info related to secure_boot. This information would be used by iLO driver for :-
    • During provisioning, driver can turn on the secure boot capability to
      validate signatures of bootloaders and kernel.
    • During cleaning stage of teardown, clean_step could be added to initiate steps to clear the signatures, if any stored onto the node signature database.

Preparing boot and deploy images

Disk Image builder changes are required to integrate signed shim and grub bootloaders. shim bootloader is required as it is signed using Microsoft UEFI CA signature and recognises corresponding linux vendors certificate as a valid certificate. Secure boot enabled Proliant UEFI systems are pre-loaded with Microsoft UEFI CA signatures. User signed images can be supported but users needs to manually configure their keys to system ROM database using Proliant tools.

Alternatives

None

Data model impact

None

REST API impact

None

RPC API impact

None

Driver API impact

None

Nova driver impact

None

Security impact

This enhances security. Only correctly signed firmware, bootloader and OS can be booted. It provides users with the opportunity to run the software of their choice in the most secure manner.

Other end user impact

Users need to use properly signed deploy and boot components. Currently iLO driver would support deploy and boot images having shim and grub signed by Linux OS vendors. If user wants to use custom signed images, then he would need to manually configure their keys to UEFI using Proliant tools.

Scalability impact

None

Performance Impact

There is no performance impact due to signature validation in secure boot.

Other deployer impact

User can deploy only signed images with secure boot enabled. If the user wants to use custom unsigned images for decommissioning then he would need to disable secure boot on the node as part of clean_step during teardown stage before booting into such custom images.

Developer impact

None

Implementation

Assignee(s)

primary author and contact.

Primary assignee:
Shivanand Tendulker (stendulker@gmail.com)

Work Items

  1. Implement code changes for supporting secure boot.
  1. Implement secure boot iLO drivers.
  2. Changes into Nova Virt Driver to pass capability information in the flavor as instance info. It is being proposed as part of following design spec. https://review.openstack.org/136104

Dependencies

  1. DIB changes are required to add signed shim and grub2 to the ubuntu cloud image creation using disk-image-create and ramdisk-image-create scripts.
  2. Changes in Nova Virt driver to pass capabality information from flavor to driver through instance info.

Testing

Unit tests would be added for all newly added code.

Upgrades and Backwards Compatibility

None

Documentation Impact

Newly added functionality would be appropriately documented.

References

Discover node properties for iLO drivers https://review.openstack.org/#/c/103007

Ironic Management Interfaces to support UEFI Secure Boot https://review.openstack.org/#/c/135845