How to enable Secure Boot using systemd-boot, sdbootutil and sbctl?

dan2704 · October 5, 2025, 5:35pm

I am doing a command line installation of openSUSE Tumbleweed.

I am trying to enable Secure Boot using systemd-boot, sdbootutil and sbctl.
Unfortunately I cannot find or lack some information and I need some help please.

Currently, after preparing the disks and installing everything I need, I proceed with:

# Installing bootloader
zypper in -y systemd-boot
bootctl install

# Installing boot helpers
zypper in -y sdbootutil fde-tools tpm2-0-tss

# Deleting all .efi entries from NVRAM
efibootmgr --delete-bootnum --bootnum "<num here>"

# UEFI Secure Boot is in "Setup Mode" (and keys have been deleted)

# TPM auto-unlock for LUKS devices
sdbootutil enroll --method=tpm2

# Generating and enrolling keys for Secure Boot
zypper in -y sbctl
sbctl create-keys
sbctl enroll-keys -m

# Updating bootloader & boot entries (I am also using the Snapper integration)
sdbootutil install
sdbootutil set-timeout -- 8
sdbootutil add-all-kernels

At this point I was hoping for things (bootloader, initrd, kernel) to be signed but that is not the case.
… and running “sbctl verify” confirms this.

I see that sbctl comes with “/usr/lib/kernel/install.d/91-sbctl.install” which should automatically sign the kernel when there’s an update. So my guess is I just need to force the update of the kernel.

What hooks do I need to install/configure such that the bootloader and initrd are signed automatically on updates?

I’ve also looked into UKI but I am confused on the state.
I understand there’s uki-tool but it’s still experimental so maybe I could use systemd-ukify?

I am not sure on how to integrate the UKI in the entire pipeline such that it’s not broken on system updates.

What is the recommended path?

malcolmlewis · October 5, 2025, 5:46pm

@dan2704 Hi, I just selected systemd-boot at install? If you run fwupdmgr security is “UEFI secure boot: Enabled”

Edit: I preconfigured the disk and allowed 4GB for /boot/efi (Just like Aeon).

dan2704 · October 5, 2025, 6:01pm

@malcolmlewis I am not using the UI installer, I am doing a command line install using chroot.

malcolmlewis · October 5, 2025, 6:06pm

Ok, if you use sdbootutil -v add-all-kernels to give verbose output, do you see the entries created etc;

ll /boot/efi/
total 12
drwxr-xr-x.  4 root root 4096 Jul  8 06:43 EFI
drwxr-xr-x.  3 root root 4096 Oct  5 11:31 loader
drwxr-xr-x. 11 root root 4096 Oct  2 22:21 opensuse-tumbleweed

arvidjaar · October 5, 2025, 6:24pm

sdbootutil does not use kernel-install.

dan2704 · October 5, 2025, 6:49pm

bootctl install

Created "/boot/efi/EFI".
Created "/boot/efi/EFI/systemd".
Created "/boot/efi/EFI/BOOT".
Created "/boot/efi/loader".
Created "/boot/efi/loader/keys".
Created "/boot/efi/loader/entries".
Created "/boot/efi/EFI/Linux".
Copied "/usr/lib/systemd/boot/efi/systemd-bootx64.efi" to "/boot/efi/EFI/systemd/systemd-bootx64.efi".
Copied "/usr/lib/systemd/boot/efi/systemd-bootx64.efi" to "/boot/efi/EFI/BOOT/BOOTX64.EFI".
Random seed file /boot/efi/loader/random-seed successfully written (32 bytes).
Created EFI boot entry "Linux Boot Manager".

sdbootutil enroll --method=tpm2

Recovery PIN: hbfercub-rdgrrghc-fdlluirv-ibftkgei-ktjdktjn-ldjghbct-ekdgbuhn-vijktlnt
You can also scan it with your mobile phone:
*{some QR code}*                                                                                
NVIndex policy created

🔐 Please enter current passphrase for disk /dev/nvme0n1p2: ••••                    
New TPM2 token enrolled as key slot 1.

sbctl create-keys
Created Owner UUID ea302f7e-0b1c-47e4-b0e0-b17398616825
Creating secure boot keys...✓ 
Secure boot keys created!

sbctl enroll-keys -m
Enrolling keys to EFI variables...
With vendor keys from microsoft...✓ 
Enrolled keys to the EFI variables!

sdbootutil install
NVIndex policy created

sdbootutil set-timeout -- 8
NVIndex policy created

sdbootutil -v add-all-kernels

Installing all kernels
Found kernel 6.17.0-1-default = 35ef7aeaef5806afdbf9174915fb9a039bfc2828
Installing kernel 6.17.0-1-default
Found existing initrd /opensuse-tumbleweed/6.17.0-1-default/initrd-7e824ec74e0f9da29b62fb37c681d54352291fe6
Required free space in ESP: 15836 KB
Reusing /boot/efi/opensuse-tumbleweed/6.17.0-1-default/linux-35ef7aeaef5806afdbf9174915fb9a039bfc2828
 /boot/efi/loader/entries/opensuse-tumbleweed-6.17.0-1-default-1.conf unchanged
Loading config file /etc/sysconfig/fde-tools
Generating TPM2 predictions with systemd-pcrlock
Generating TPM2 predictions with systemd-pcrlock (systemd-boot)
NVIndex policy created

sbctl status

|Installed:|✓ sbctl is installed|
|---|---|
|Owner GUID:|ea302f7e-0b1c-47e4-b0e0-b17398616825|
|Setup Mode:|✓ Disabled|
|Secure Boot:|✗ Disabled|
|Vendor Keys:|microsoft|

sbctl verify

Verifying file database and EFI images in /boot/efi...
✗ /boot/efi/EFI/BOOT/BOOTX64.EFI is not signed
failed to verify file /boot/efi/EFI/systemd/boot.csv: /boot/efi/EFI/systemd/boot.csv: invalid pe header
failed to verify file /boot/efi/EFI/systemd/installed_by_sdbootutil: /boot/efi/EFI/systemd/installed_by_sdbootutil: invalid pe header
failed to verify file /boot/efi/EFI/systemd/measure-pcr-prediction: /boot/efi/EFI/systemd/measure-pcr-prediction: invalid pe header
failed to verify file /boot/efi/EFI/systemd/measure-pcr-prediction.sha256: /boot/efi/EFI/systemd/measure-pcr-prediction.sha256: invalid pe header
failed to verify file /boot/efi/EFI/systemd/pcrlock.json: /boot/efi/EFI/systemd/pcrlock.json: invalid pe header
✗ /boot/efi/EFI/systemd/systemd-bootx64.efi is not signed
failed to verify file /boot/efi/loader/entries/opensuse-tumbleweed-6.17.0-1-default-1.conf: /boot/efi/loader/entries/opensuse-tumbleweed-6.17.0-1-default-1.conf: invalid pe header
failed to verify file /boot/efi/loader/entries.srel: /boot/efi/loader/entries.srel: invalid pe header
failed to verify file /boot/efi/loader/loader.conf: /boot/efi/loader/loader.conf: invalid pe header
failed to verify file /boot/efi/loader/random-seed: /boot/efi/loader/random-seed: invalid pe header
failed to verify file /boot/efi/opensuse-tumbleweed/6.17.0-1-default/initrd-7e824ec74e0f9da29b62fb37c681d54352291fe6: /boot/efi/opensuse-tumbleweed/6.17.0-1-default/initrd-7e824ec74e0f9da29b62fb37c681d54352291fe6: invalid pe header
✗ /boot/efi/opensuse-tumbleweed/6.17.0-1-default/linux-35ef7aeaef5806afdbf9174915fb9a039bfc2828 is not signed

bootctl status

System:
      Firmware: n/a (n/a)
 Firmware Arch: x64
   Secure Boot: disabled (unknown)
  TPM2 Support: yes
  Measured UKI: no
  Boot into FW: supported

Random Seed:
 System Token: set
       Exists: yes

Available Boot Loaders on ESP:
          ESP: /boot/efi (/dev/disk/by-partuuid/6926d525-d2c6-4f4a-80fe-14433e698cab)
         File: ├─/EFI/systemd/systemd-bootx64.efi (systemd-boot 257.9+suse.23.gc139debf2c)
               └─/EFI/BOOT/BOOTX64.EFI (systemd-boot 257.9+suse.23.gc139debf2c)

Boot Loaders Listed in EFI Variables:
        Title: openSUSE Boot Manager (systemd-boot)
           ID: 0x0001
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/ba2c8303-b48b-4877-ad19-450382689682
         File: └─/EFI/systemd/systemd-bootx64.efi

        Title: Linux Boot Manager
           ID: 0x0004
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/6926d525-d2c6-4f4a-80fe-14433e698cab
         File: └─/EFI/systemd/systemd-bootx64.efi

        Title: UEFI Samsung Flash Drive FIT 0375022010004300
           ID: 0x0003
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/27b06976-221c-4bf5-96a0-57e188823e80
         File: └─/EFI/Boot/BootX64.efi

        Title: Linux Boot Manager
           ID: 0x0000
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/ba2c8303-b48b-4877-ad19-450382689682
         File: └─/EFI/systemd/systemd-bootx64.efi

        Title: UEFI KXG70ZNV512G NVMe KIOXIA 512GB 922A10A3KTF5 1
           ID: 0x0002
       Status: active, boot-order
    Partition: /dev/disk/by-partuuid/ba2c8303-b48b-4877-ad19-450382689682
         File: └─/EFI/Boot/BootX64.efi

Boot Loader Entries:
        $BOOT: /boot/efi (/dev/disk/by-partuuid/6926d525-d2c6-4f4a-80fe-14433e698cab)
        token: opensuse-tumbleweed

Default Boot Loader Entry:
         type: Boot Loader Specification Type #1 (.conf)
        title: openSUSE Tumbleweed 20251003
           id: opensuse-tumbleweed-6.17.0-1-default-1.conf
       source: /boot/efi//loader/entries/opensuse-tumbleweed-6.17.0-1-default-1.conf (on the EFI System Partition)
     sort-key: opensuse-tumbleweed
      version: 1@6.17.0-1-default
        linux: /boot/efi//opensuse-tumbleweed/6.17.0-1-default/linux-35ef7aeaef5806afdbf9174915fb9a039bfc2828
       initrd: /boot/efi//opensuse-tumbleweed/6.17.0-1-default/initrd-7e824ec74e0f9da29b62fb37c681d54352291fe6
      options: cryptdevice=UUID=7b886caa-3c48-412f-be01-bb8d85f1388e:root root=/dev/mapper/root quiet systemd.show_status=yes  rootflags=subvol=@/.snapshots/1/snapshot

dan2704 · October 5, 2025, 6:52pm

Right, I was talking about sbctl:

rpm -ql sbctl

/usr/lib/kernel
/usr/lib/kernel/install.d
/usr/lib/kernel/install.d/91-sbctl.install
/usr/sbin/sbctl
/usr/share/bash-completion/completions/sbctl
/usr/share/doc/packages/sbctl
/usr/share/doc/packages/sbctl/README.md
/usr/share/fish
/usr/share/fish/vendor_completions.d
/usr/share/fish/vendor_completions.d/sbctl.fish
/usr/share/licenses/sbctl
/usr/share/licenses/sbctl/LICENSE
/usr/share/man/man5/sbctl.conf.5.gz
/usr/share/man/man8/sbctl.8.gz
/usr/share/zsh
/usr/share/zsh/site-functions
/usr/share/zsh/site-functions/_sbctl

That’s why I was saying maybe I should force the kernel update to trigger that kernel sign. I was mentioning this in the context of seamless sign on system updates.

arvidjaar · October 6, 2025, 3:48am

And I tell you what program makes use of /usr/lib/kernel/install.d.

You may try removing sdbootutil in which case update-bootloader should fall back to kernel-install. But then you will lose snapshot support.

dan2704 · October 10, 2025, 9:42am

Yes, that’s the thing, I don’t want to lose snapshot support (with all the bells and whistles).

I configured dracut to build a UKI (that part works). I assumed (very badly I guess) that would go through kernel-install so the sbctl hook (91-sbctl.install) would auto-sign it.

Regardless, I found out that the UKI is not discovered by sdbootutil, it still generates entries for separate kernel+initrd files.

I am a bit confused on how to achieve my goal and not sure if it’s supported without some custom hooks.

arvidjaar · October 10, 2025, 12:20pm

No

There was some attempt to add support for snapshots to the kernel-install, but it went nowhere.

kernel-install: snapshot support by lnussel · Pull Request #25801 · systemd/systemd · GitHub

system · November 9, 2025, 12:21pm

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