.. fyl1552681364538
.. _use-uefi-secure-boot:
====================
Use UEFI Secure Boot
====================
Secure Boot is supported in |UEFI| installations only. It is not used when
booting |prod| as a legacy boot target.
|prod| 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 |prod| system from a version which does not support secure
boot to a version that does, do not enable secure boot in |UEFI| firmware until
the upgrade is complete.
For each node that is going to use secure boot, you must populate the |prod|
public certificate/key in the |UEFI| 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 |UEFI| certificate database. These certificates may be
required to boot |UEFI| drivers for video cards, RAID controllers, or NICs
\(for example, the |PXE| 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 |UEFI| firmware of each node for that node
to be protected by secure boot.
.. only:: partner
.. include:: /_includes/extract-certificate-from-iso-181be684e2e5.rest
.. only:: starlingx
------------------------------------------------------------------------------
Build considerations for signing packages for UEFI Secure Boot -- CentOS build
------------------------------------------------------------------------------
The |prod| build environment has provisions for calling out to a signing
server for purposes of creating a secure boot load. At this time |prod|
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:
.. code-block:: none
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:
.. code-block:: none
# 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.
.. code-block:: none
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:
.. code-block:: none
sbsign --key $KEYPATH/$KEYNAME.key --cert $KEYPATH/$KEYNAME.crt --output $SIGNEDFILE $UNSIGNEDFILE
Keys and certificates:
.. code-block:: none
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:
.. code-block:: none
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.
------------------------------------------------------------------------------
Build considerations for signing packages for UEFI Secure Boot -- Debian build
------------------------------------------------------------------------------
The |prod| build environment has provisions for calling out to a signing
server for purposes of creating a secure boot load. At this time |prod|
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
``Debian`` build. You may find it helpful in implementing your own signing
server.
The secure boot verification sequence of StarlingX Debian is:
UEFI firmware verify shim image;
shim verify grub image;
grub verify kernel image and initramfs image.
Bootloader shim will enroll the public key to verify grub image.
Bootloader grub-efi will enroll the public key to verify kernel and initramfs image.
The following process should be followed to request a secure boot signing:
.. code-block:: none
......
stx control keys-add --key-type=signing-server --key=[key file]
stx shell
downloader
build-pkgs
export SIGNING_SERVER="signing_user@signing_server_ip"
sign-secure-boot_debian
build-image
The "key file" is the private key generated by "ssh-keygen -t rsa"
and used to setup signing server access without password.
The signing script ``sign-secure-boot_debian`` does secure boot signing for
|prod| Debian in this way:
.. code-block:: none
(1) Sign shim / grub images
The shim/grub efi images are obtained from extracted shim/grub
packages, and they are sent to signing server and signed there and
copied back. Then the shim/grub packages are repacked with the
signed efi images.
(2) Sign kernel images and LockDown.efi
The file sign_rootfs-post-scripts is inserted to where the
hook script "rootfs-post-scripts" is defined in the LAT config file
base-bullseye.yaml. This will sign kernel images and LockDown.efi
on signing server in the LAT build process.
The "rootfs-post-scripts" is the hook in LAT tool running after rootfs
is created.
(3) Sign initramfs and mini initrd
The file sign_initramfs-sign-script is inserted to where the hook
script "initramfs-sign-script" is defined in the LAT config file
base-bullseye.yaml. This will sign initramfs and mini initrd on signing server in
the LAT build process.
The "initramfs-sign-script" is the hook in LAT tool running after initramfs
is created.
Above (2) and (3) prepare the signing codes in LAT config file.
After build-image is triggered, the signing codes inserted in LAT config files will
run on LAT container in the right sequence.
Here is an example for signing an image file in sign-secure-boot_debian:
.. code-block:: none
# Request upload path from signing server.
REQUEST=$(ssh ${SSH_OPTION_NOCHECKING} ${SIGNING_SERVER} sudo /opt/signing/sign-debian.sh -r)
UPLOAD_PATH=${REQUEST#*Upload: }
# Copy shimx64.efi to signing server
scp ${SSH_OPTION_NOCHECKING} shimx64.efi ${SIGNING_SERVER}:${UPLOAD_PATH}
# Sign shimx64.efi
ssh ${SSH_OPTION_NOCHECKING} ${SIGNING_SERVER} sudo /opt/signing/sign-debian.sh -i ${UPLOAD_PATH}/shimx64.efi -t shim
# Copy back signed shimx64.efi which is renamed as bootx64.efi
sudo scp ${SSH_OPTION_NOCHECKING} ${SIGNING_SERVER}:${UPLOAD_PATH}/bootx64.efi ./
The sign-debian.sh in above code is the script running on signing server whose interface
is defined as below:
.. code-block:: none
Usage:
sign-debian.sh [options]
[-i <file>] - input unsigned file
[-t <type>] - type of signing to do
[-r] - request an upload path
Types of signing:
-t shim - signs a shim EFI binary with the boot key
-t grub - signs a GRUB EFI binary with the shim key
-t shimtool - signs a shim tool EFI binary with the shim key
-t grub-gpg - signs a kernel/initrd/grub.cfg with the grub gpg key
Keys management:
.. code-block:: none
Upstream stx public keys repo: https://opendev.org/starlingx/public-keys
The keys under cgcs-root/public-keys are the public keys used in
the verification process of secure boot process for StarlingX
Debian.
Keys Introduction:
tis-boot.crt: it is the public key flashed into UEFI to verify
bootx64.efi (signed shim image shimx64.efi);
tis-shim.der: it is the public key used by shim to verify
grubx64.efi (signed grub image) and mmx64.efi
(signed shim tool image);
boot_pub_key: it is the public key used by grub to verify signed
kernel image and initramfs image and efitools image and so on.
TiBoot.crt: it is the same pub key with tis-boot.crt (pem) as a
der format. It is installed as /CERTS/TiBoot.crt in the efi.img
which is in the iso image.
The following ways can be used to create substitute keys:
(1)example to create tis-boot.crt/TiBoot.crt
openssl req -new -x509 -newkey rsa:2048 -keyout BOOT.priv -outform DER -out BOOT.der -days 36500 -subj "/CN=My Boot/" -nodes
openssl x509 -inform der -in BOOT.der -out BOOT.pem
cp BOOT.pem tis-boot.crt
cp BOOT.priv tis-boot.key
cp BOOT.der TiBoot.crt
The tis-boot.crt and tis-boot.key are used to sign images mentioned above (shim image).
The tis-shim.crt/tis-shim.der/tis-shim.key can be created in the same way, and used to sign images mentioned above (grub image and shim tool image).
(2)example to create boot_pub_key
#!/bin/bash
key_dir="./"
priv_key="${key_dir}/BOOT-GPG-PRIVKEY-SecureBootCore"
pub_key="${key_dir}/BOOT-GPG-KEY-SecureBootCore"
name_real="SecureBootCore"
pw="PASSWORD"
USE_PW="Passphrase: PASSWORD"
cat >"${key_dir}/gen_keyring" <<EOF
Key-Type: RSA
Key-Length: 4096
Name-Real: ${name_real}
Name-Comment: EXAMPLE
Name-Email: a@b.com
Expire-Date: 0
${USE_PW}
%commit
%echo keyring ${name_real} created
EOF
gpg --homedir "${key_dir}" --batch --yes --gen-key "${key_dir}/gen_keyring"
gpg --homedir "${key_dir}" -k
gpg --homedir "${key_dir}" --export --armor "${name_real}" > "${pub_key}"
gpg --homedir "${key_dir}" --export-secret-keys --pinentry-mode=loopback --passphrase "${pw}" --armor "${name_real}" > "${priv_key}"
gpg --homedir "${key_dir}" --export "${name_real}" > ${key_dir}/boot_pub_key
The BOOT-GPG-PRIVKEY-SecureBootCore is used to sign images mentioned above (kernel image and initramfs image and efitools image and so on).
Signing commands to sign image files:
.. code-block:: none
Signing command to sign type shim/grub/shimtool image files:
sbsign --key $KEYPATH/$KEYNAME.key \
--cert $KEYPATH/$KEYNAME.crt \
--output $SIGNEDFILE \
$UNSIGNEDFILE
for "-t shim", the output file name is bootx64.efi;
for "-t grub", the output file name is grubx64.efi;
for "-t shimtool", the output file name is ${UNSIGNEDFILE}.signed.
Signing command to sign type grub-gpg files:
gpg2 --batch \
--homedir ${GPGHOME} \
--passphrase PASSWORD \
--import ${KEYPATH}/${BOOT_GPG_PRI_KEY}
echo 'PASSWORD' | \
gpg2 --pinentry-mode loopback \
--batch \
--homedir ${GPGHOME} \
-u SecureBootCore \
--detach-sign \
--passphrase-fd 0 \
${FILEIN}
Please pay attention to the keys they should use according to [Keys management] section.