sbctl - Secure Boot Manager

sbctl intends to be a user-friendly secure boot key manager capable of setting up secure boot, offer key management capabilities, and keep track of files that needs to be signed in the boot chain.

It is written top-to-bottom in Golang using go-uefi for the API layer and doesn't rely on existing secure boot tooling. It also tries to sport some integration testing towards tianocore utilizing vmtest.

Features

• User-friendly
• Manages secure boot keys
• Live enrollment of keys
• Signing database to help keep track of files to sign
• Verify ESP of files missing signatures
• EFI stub generation
• JSON output

Roadmap to 1.0

• Key rotation
• TPM support
• Hardware token support
• Configuration Files
• Automatic boot chain signing using the Boot Loader Interface

Dependencies

• util-linux (using lsblk)
• binutils (using objcopy)
• Go >= 1.20
• asciidoc (only for building)

Installation

To fetch, build and install sbctl from the Github source:

$ go install github.com/foxboron/sbctl/cmd/sbctl@latest
$ $(go env GOPATH)/bin/sbctl

To install through git:

$ git clone https://github.com/foxboron/sbctl.git
$ cd sbctl
$ make
$ ./sbctl

Available packages

For Arch Linux:

# pacman -S sbctl

For Alpine Linux:

# apk add sbctl

For Gentoo Linux:

# emerge --ask app-crypt/sbctl

For openSUSE:

# zypper install sbctl

For Fedora Linux (unofficial package):

# dnf copr enable chenxiaolong/sbctl
# dnf install sbctl

You can find a updated list of sbctl packages on Repology.

In addition, sbctl is also available for Ubuntu (unofficial). Follow the Expert Download links to find installation instructions according to your operating system.

Support and development channel

Development discussions and support happens in #sbctl on the libera.chat IRC network.

Usage

$ sbctl
Secure Boot Key Manager

Usage:
  sbctl [command]

Available Commands:
  bundle               Bundle the needed files for an EFI stub image
  create-keys          Create a set of secure boot signing keys
  enroll-keys          Enroll the current keys to EFI
  export-enrolled-keys Export already enrolled keys from the system
  generate-bundles     Generate all EFI stub bundles
  help                 Help about any command
  import-keys          Import keys into sbctl
  list-bundles         List stored bundles
  list-enrolled-keys   List enrolled keys on the system
  list-files           List enrolled files
  remove-bundle        Remove bundle from database
  remove-file          Remove file from database
  reset                Reset Secure Boot Keys
  rotate-keys          Rotate secure boot keys with new keys.
  setup                Setup sbctl
  sign                 Sign a file with secure boot keys
  sign-all             Sign all enrolled files with secure boot keys
  status               Show current boot status
  verify               Find and check if files in the ESP are signed or not

Flags:
      --config string      Path to configuration file
      --debug              debug logging
      --disable-landlock   disable landlock
  -h, --help               help for sbctl
      --json               Output as json
      --quiet              Mute info from logging

Use "sbctl [command] --help" for more information about a command.

Key creation and enrollment

See example enrollment for a workflow with screenshots of real firmware setup menus.

# sbctl status
Installed:  ✘ Sbctl is not installed
Setup Mode: ✘ Enabled
Secure Boot:    ✘ Disabled

# sbctl create-keys
Created Owner UUID a9fbbdb7-a05f-48d5-b63a-08c5df45ee70
Creating secure boot keys...✔
Secure boot keys created!

# sbctl enroll-keys
Enrolling keys to EFI variables...✔
Enrolled keys to the EFI variables!

# sbctl status
Installed:  ✔ Sbctl is installed
Owner GUID: a9fbbdb7-a05f-48d5-b63a-08c5df45ee70
Setup Mode: ✔ Disabled
Secure Boot:    ✘ Disabled

// Reboot and enable secure boot in the bios!
# sbctl status
Installed:  ✔ Sbctl is installed
Owner GUID: a9fbbdb7-a05f-48d5-b63a-08c5df45ee70
Setup Mode: ✔ Disabled
Secure Boot:    ✔ Enabled

Signatures

# sbctl verify
Verifying file database and EFI images in /efi...
✘ /boot/vmlinuz-linux is not signed
✘ /efi/EFI/BOOT/BOOTX64.EFI is not signed
✘ /efi/EFI/BOOT/KeyTool-signed.efi is not signed
✘ /efi/EFI/Linux/linux-linux.efi is not signed
✘ /efi/EFI/arch/fwupdx64.efi is not signed
✘ /efi/EFI/systemd/systemd-bootx64.efi is not signed

# sbctl sign -s /efi/EFI/BOOT/BOOTX64.EFI
✔ Signed /efi/EFI/BOOT/BOOTX64.EFI...

# sbctl sign -s /efi/EFI/arch/fwupdx64.efi
✔ Signed /efi/EFI/arch/fwupdx64.efi...

# sbctl sign -s /efi/EFI/systemd/systemd-bootx64.efi
✔ Signed /efi/EFI/systemd/systemd-bootx64.efi...

# sbctl sign -s /usr/lib/fwupd/efi/fwupdx64.efi -o /usr/lib/fwupd/efi/fwupdx64.efi.signed
✔ Signed /usr/lib/fwupd/efi/fwupdx64.efi...

# sbctl verify
Verifying file database and EFI images in /efi...
✔ /usr/lib/fwupd/efi/fwupdx64.efi.signed is signed
✔ /efi/EFI/BOOT/BOOTX64.EFI is signed
✔ /efi/EFI/arch/fwupdx64.efi is signed
✔ /efi/EFI/systemd/systemd-bootx64.efi is signed
✘ /boot/vmlinuz-linux is not signed
✘ /efi/EFI/BOOT/KeyTool-signed.efi is not signed
✘ /efi/EFI/Linux/linux-linux.efi is not signed

# sbctl list-files
/boot/vmlinuz-linux
Signed:     ✘ Not Signed

/efi/EFI/BOOT/KeyTool-signed.efi
Signed:     ✘ Not Signed

/efi/EFI/Linux/linux-linux.efi
Signed:     ✘ Not Signed

/efi/EFI/arch/fwupdx64.efi
Signed:     ✔ Signed

/efi/EFI/BOOT/BOOTX64.EFI
Signed:     ✔ Signed

/usr/lib/fwupd/efi/fwupdx64.efi
Signed:     ✔ Signed
Output File:    /usr/lib/fwupd/efi/fwupdx64.efi.signed

/efi/EFI/systemd/systemd-bootx64.efi
Signed:     ✔ Signed

Generate Unified Kernel Images (UKI)

Note: It is generally recommended to use the initramfs generator for this. mkinitcpio and dracut support this through their respective --uki and --uefi flags, or the ukify tool from systemd.

This feature is considered a second class citizen in sbctl.

# sbctl bundle -s -i /boot/intel-ucode.img \
      -l /usr/share/systemd/bootctl/splash-arch.bmp \
      -k /boot/vmlinuz-linux \
      -f /boot/initramfs-linux.img \
      /efi/EFI/Linux/linux-linux.efi
Wrote EFI bundle /efi/EFI/Linux/linux-linux.efi

# sbctl list-bundles
Enrolled bundles:

/efi/EFI/Linux/linux-linux.efi
    Signed:     ✔ Signed
    ESP Location:   /efi
    Output:     └─/EFI/Linux/linux-linux.efi
    EFI Stub Image:   └─/usr/lib/systemd/boot/efi/linuxx64.efi.stub
    Splash Image:       ├─/usr/share/systemd/bootctl/splash-arch.bmp
    Cmdline:        ├─/etc/kernel/cmdline
    OS Release:     ├─/usr/lib/os-release
    Kernel Image:       ├─/boot/vmlinuz-linux
    Initramfs Image:    └─/boot/initramfs-linux.img
    Intel Microcode:      └─/boot/intel-ucode.img


# sbctl generate-bundles
Generating EFI bundles....
Wrote EFI bundle /efi/EFI/Linux/linux-linux.efi

Yubikey Support

To create a signing key with a yubikey, use the --keytype yubikey flag with the create-key command. For example:

$ sbctl create-keys --keytype yubikey
Created Owner UUID da774306-c007-4fb7-835d-91146a8795ef
Please connect yubikey! Waiting 90 seconds...
Using RSA4096 Key MD5: bb466f955d182cfd38225a5c326c5329 in Yubikey PIV Signature Slot
Creating Platform Key (PK) key...
Please press Yubikey to confirm presence for RSA4096 MD5: bb466f955d182cfd38225a5c326c5329
Using RSA4096 Key MD5: bb466f955d182cfd38225a5c326c5329 in Yubikey PIV Signature Slot
Creating Key Exchange Key (KEK) key...
Please press Yubikey to confirm presence for RSA4096 MD5: bb466f955d182cfd38225a5c326c5329
Using RSA4096 Key MD5: bb466f955d182cfd38225a5c326c5329 in Yubikey PIV Signature Slot
Creating Database Key (db) key...
Please press Yubikey to confirm presence for RSA4096 MD5: bb466f955d182cfd38225a5c326c5329
✓
Secure boot keys created!

The command will create a RSA4096 key in the Yubikey's PIV Signature Slot. sbctl will then use the key for signing the UKI. To specify the PIN for the Yubikey, use the SBCTL_YUBIKEY_PIN environment variable:

$ SBCTL_YUBIKEY_PIN=123123 sbctl create-keys --keytype yubikey

Remember to specify the SBCTL_YUBIKEY_PIN when signing the UKI or performing operations that will trigger the sbctl hooks (like mkinitcpio).