docs/doc/source/security/kubernetes/use-uefi-secure-boot.rst

Use UEFI Secure Boot

Secure Boot is supported in installations only. It is not used when booting as a legacy boot target.

currently does not support switching from legacy to UEFI mode after a system has been installed. Doing so requires a reinstall of the system. This also means that upgrading from a legacy install to a secure boot install (UEFI) is not supported.

When upgrading a system from a version which does not support secure boot to a version that does, do not enable secure boot in firmware until the upgrade is complete.

For each node that is going to use secure boot, you must populate the public certificate/key in the Secure Boot authorized database in accordance with the board manufacturer's process. This must be done for each node before starting installation.

You may need to work with your hardware vendor to have the certificate installed.

There is often an option in the UEFI setup utility which allows a user to browse to a file containing a certificate to be loaded in the authorized database. This option may be hidden in the UEFI setup utility unless UEFI mode is enabled, and secure boot is enabled.

Many motherboards ship with Microsoft secure boot certificates pre-programmed in the certificate database. These certificates may be required to boot drivers for video cards, RAID controllers, or NICs (for example, the boot software for a NIC may have been signed by a Microsoft certificate). While certificates can usually be removed from the certificate database (again, this is UEFI implementation specific) it may be required that you keep the Microsoft certificates to allow for complete system operation.

Mixed combinations of secure boot and non-secure boot nodes are supported. For example, a controller node may secure boot, while a worker node may not. Secure boot must be enabled in the firmware of each node for that node to be protected by secure boot.

starlingx

Build considerations for signing packages for UEFI Secure Boot

The build environment has provisions for calling out to a signing server for purposes of creating a secure boot load. At this time does not include an implementation of the signing server. The following describes how the signing process is intended to work in the context of a CentOS build. You may find it helpful in implementing your own signing server.

The following environmental variables should be defined before attempting to request a secure boot signing:

export SIGNING_SERVER=<signing-host>
export SIGNING_USER=<signing-user>
export SIGNING_SERVER_SCRIPT=<path-to-signing-script>

'build-pkgs' further requires that "$USER" == "jenkins", and

export FORMAL_BUILD=1

If the above criteria is met, it calls into sign-secure-boot.

This is an example of the call sequence:

# Set up the server side directory for files transfers.
UPLOAD_PATH=`ssh $SIGNING_USER@$SIGNING_SERVER sudo $SIGNING_SCRIPT -r`

# upload the original package
scp -q $FILE $SIGNING_USER@$SIGNING_SERVER:$UPLOAD_PATH

# Request that the package be signed
ssh $SIGNING_USER@$SIGNING_SERVER sudo $SIGNING_SCRIPT -v -i $UPLOAD_PATH/$(basename $FILE) $UNSIGNED_OPTION -t $TYPE > $TMPFILE

# Download the file from the signing server
DOWNLOAD_FILENAME=$(basename $OUTPUT_FILE)
scp -q $SIGNING_USER@$SIGNING_SERVER:$OUTPUT_FILE $(dirname $FILE)


Within the signing server there are two keys used for signing, known as
the `boot` key and the `shim` key. The public half of the `boot` key
must be manually added to the secure boot keychain in the firmware. The
`boot` key signs the first executable loaded, contained in the `shim`
package. The first executable must then install the public half of the
`shim` key (automatically) before passing control to the grub, and
ultimately the kernel, both of which are signed by the private `shim`
key.

Three packages need to be passed to the signing server. The RPMs need
to be unpacked, the relevant binaries signed with the correct keys, and
the RPMs reassembled.

package    key   files to sign
=========  ====  ===========================
shim       boot  BOOTX64, shim, shimx64
           shim  MokManager, fallback, mmx64, fbx64
grub       shim  grubx64.efi, gcdx64.efi
kernel     shim

Note

shim files that are required to be signed might might include a .efi or .EFI suffix.

Some files may be absent in newer packages.

Example:

sbsign --key $KEYPATH/$KEYNAME.key --cert $KEYPATH/$KEYNAME.crt  --output $SIGNEDFILE $UNSIGNEDFILE

Keys and certificates:

boot.crt - Certificate to boot (to be programmed in firmware)
boot.key - Private key with which to sign shim
shim.crt - Certificated embedded within shim used to validate kernel, grub
shim.key - Private key with which to sign kernel/grub

Key generation:

openssl req -new -x509 -newkey rsa:2048 -keyout $KEY.key -out $KEY.pem -days 3650
openssl x509 -in $KEY.pem -out $KEY.crt -outform DER

Note

boot.crt should be copied to cgcs-root/build-tools/certificates/TiBoot.crt for inclusion during the build-iso step.