[Bug 2004203] [NEW] With needrestart, apt-get does not respect non-interactive instruction when upgrading services

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Juerg Haefliger (juergh):

[ Impact ]

 * Servers and other systems running `unattended-upgrades` will not
automatically restart services that use binaries that were updated, even
when explicitly configured to do so. This may lead to security holes
remaining open or other misbehaviour, until the machine or services are
restarted for other reasons. This defeats the primary functionality of
that package.

[ Test Plan ]

 * Use an Ubuntu Jammy test system with typical configuration. I used a
fresh LXD container.

 * Install `unattended-upgrades`. Ensure `needrestart` and `update-
notifier-common` are also installed, but that should usually be the
case.

 * Configure `needrestart` to automatically restart services:
   * Create `/etc/needrestart/conf.d/auto-restart.conf` with content:
        $nrconf{restart} = 'a';

 * Locate any package that some running service has an indirect dependency on (such as libc, libssl3, python, java, etc). Using something more uncommon like java might be easier than something that has a lot of dependencies like libc/libssl3.
    * In my case I chose `<dep>=libc6` and `<service>=cron`.

 * `apt list -a <dep>` to see other versions of the package. Usually
there will be an older version available from the main repository, while
the current version is from the update or security repository.

 * `sudo apt install <dep>=<version>` to explicitly downgrade the package to the older version. (You may need to select a different package, or more packages, to resolve conflicts or avoid removing other packages.)
    * Observe that the dependent services will be automatically restarted when you do this. (I checked this via the start time in `systemctl status <service>`.)

 * `sudo unattended-upgrade` to request immediate upgrade of outdated packages, which should reverse the above change.
    * Observe that while `/var/log/unattended-upgrades/unattended-upgrades-dpkg.log` reports `NEEDRESTART-SVC` as expected, the services in question are not actually restarted. (Again I confirmed this via `systemctl status <service>`.)

[ Where problems could occur ]

    * There is a low chance of regressions given that the patch has been
included in the packaged deb since kinetic.

    * Since this bug has been around for some time a number of users may have implemented workarounds in their scripts that this fix could break.
      * I have tested at least one workaround which was discussed on the associated github issue (https://github.com/liske/needrestart/issues/270) and confirmed that this fix does not break it. Namely running `needrestart -r a -f readline` after `unattended-upgrade` does not prompt and does not cause any additional restarts.

    * Someone could have been relying on the broken behavior to avoid
automatic restarts. This seems unlikely, as it is directly against the
described behavior of the package.

[ Other Info ]

Related: https://bugs.launchpad.net/ubuntu/+source/unattended-upgrades/+bug/2055280
Related: https://github.com/liske/needrestart/issues/270
Related: https://github.com/liske/needrestart/pull/214 (upstream patch)

The debdiff has been updated since security patches were released since
juergh's upload, but the fix is substantially the same.

** Affects: needrestart (Ubuntu)
     Importance: Undecided
         Status: Fix Released

** Affects: needrestart (Ubuntu Jammy)
     Importance: Undecided
         Status: Incomplete

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With needrestart, apt-get does not respect non-interactive instruction when upgrading services
https://bugs.launchpad.net/bugs/2004203
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