secureboot-db.service should not run in a container

[Ryan Harper]

1) # lsb_release -rd
Description: Ubuntu Eoan Ermine (development branch)
Release: 19.10

2) root@e1:~# apt-cache policy secureboot-db
secureboot-db:
  Installed: 1.5
  Candidate: 1.5
  Version table:
 *** 1.5 500
        500 http://archive.ubuntu.com/ubuntu eoan/main amd64 Packages
        100 /var/lib/dpkg/status

3) secureboot-db.service does not run inside a LXD container

# systemctl status secureboot-db.service
● secureboot-db.service - Secure Boot updates for DB and DBX
   Loaded: loaded (/lib/systemd/system/secureboot-db.service; enabled; vendor preset: enabled)
   Active: inactive (dead)
Condition: start condition failed at Tue 2019-08-20 20:51:09 UTC; 9s ago
           └─ ConditionVirtualization=!container was not met

Aug 20 20:42:06 e1 systemd[1]: Started Secure Boot updates for DB and DBX.
Aug 20 20:51:09 e1 systemd[1]: Condition check resulted in Secure Boot updates for DB and DBX being skipped.

4) secureboot-db.service starts and fetches keys but cannot write to /sys

# journalctl -o short-precise -b -u secureboot-db.service | egrep "(Error|Cant|chattr)"
Aug 20 20:04:18.947034 e1 chattr[285]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/KEK-8be4df61-93ca-11d2-aa0d-00e098032b8c
Aug 20 20:04:19.057942 e1 chattr[302]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/db-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:04:19.083525 e1 chattr[304]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/dbx-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:04:19.123167 e1 sbkeysync[315]: Error syncing keystore file /usr/share/secureboot/updates/dbx/MS-2016-08-08.bin
Aug 20 20:26:27.716688 e1 chattr[207]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/KEK-8be4df61-93ca-11d2-aa0d-00e098032b8c
Aug 20 20:26:27.817164 e1 chattr[224]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/db-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:26:27.855895 e1 chattr[239]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/dbx-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:26:27.893937 e1 sbkeysync[248]: Error syncing keystore file /usr/share/secureboot/updates/dbx/MS-2016-08-08.bin
Aug 20 20:38:10.105456 e1 chattr[235]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/KEK-8be4df61-93ca-11d2-aa0d-00e098032b8c
Aug 20 20:38:10.111700 e1 chattr[245]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/db-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:38:10.140787 e1 chattr[250]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/dbx-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:38:10.188091 e1 sbkeysync[262]: Error syncing keystore file /usr/share/secureboot/updates/dbx/MS-2016-08-08.bin
Aug 20 20:42:05.935136 e1 chattr[232]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/KEK-8be4df61-93ca-11d2-aa0d-00e098032b8c
Aug 20 20:42:06.015810 e1 chattr[241]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/db-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:42:06.076527 e1 chattr[258]: /usr/bin/chattr: Permission denied while reading flags on /sys/firmware/efi/efivars/dbx-d719b2cb-3d3a-4596-a3bc-dad00e67656f
Aug 20 20:42:06.116561 e1 sbkeysync[266]: Error syncing keystore file /usr/share/secureboot/updates/dbx/MS-2016-08-08.bin

This can be fixed by adding another condition to the unit.

# /etc/systemd/system/secureboot-db.service.d/override.conf
[Unit]
ConditionVirtualization=!container

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: secureboot-db 1.5
ProcVersionSignature: Ubuntu 4.15.0-58.64~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-58-generic x86_64
ApportVersion: 2.20.11-0ubuntu7
Architecture: amd64
Date: Tue Aug 20 20:48:32 2019
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=C.UTF-8
SourcePackage: secureboot-db
UpgradeStatus: No upgrade log present (probably fresh install)

[Seth Arnold (seth-arnold)]

This should also not run in a live environment, such as the installer, rescue media, etc.

Thanks

[Dimitri John Ledkov (xnox)]

I have concerns about not running this in "the installer" in case installation is actually being performed.

If installation is completed, and dbx updates are not applied it means the system is vulnerable to be attacked between installation complete & first boot (i.e. in case systems are provisioned and shipped).

Also, because we currently do not have snapd secboot dbx resealing support, we rely on live session to apply dbx revocations to seal against them during provisioning.

Can we please update curtin / subiquity to apply dbx updates, prior to doing `snap prepare-image` or installing bootloaders ?

[Dimitri John Ledkov (xnox)]

(possibly we want subiquity/curtin to apply dbx updates based on the content of the installed system, in case it downloaded updated dbx revocations..... but this may prevent booting installer again so maybe we should attempt to apply live system dbx revocations..... decisions)

[Simon Déziel (sdeziel)]

I dropped the detection of the livecd env. This can be introduced at a later point in time.