preinst writes to /root

[Julian Andres Klode]

As part of my sandboxed APT I noticed that the package failed to install as it was trying to write to /root.

/root is a user directory, not a system one, which may not even exist because the administrator changed it to like /home/root, for example, and we definitely should not be writing system files in user directories.

Preparing to unpack .../16-network-manager_1.42.4-1ubuntu4_amd64.deb ...
mkdir: cannot create directory ‘/root/NetworkManager.bak’: Read-only file system
cp: cannot create directory '/root/NetworkManager.bak/system-connections_1.42.4-1ubuntu2': No such file or directory
dpkg: error processing archive /tmp/apt-dpkg-install-x9x0Qo/16-network-manager_1.42.4-1ubuntu4_amd64.deb (--unpack):
 new network-manager package pre-installation script subprocess returned error exit status 1

[Danilo Egea Gondolfo (danilogondolfo)]

Thanks, Julian.

This behavior was introduced by the netplan integration where we create a backup of the existing network manager connections. I'll look for a better place to store the backups.

[Launchpad Janitor (janitor)]

This bug was fixed in the package network-manager - 1.42.4-1ubuntu5

---------------
network-manager (1.42.4-1ubuntu5) mantic; urgency=medium

  * d/network-manager.postinst: fix netplan migration logic.
    The "continue" is being executed in a subshell so it's not skipping the
    next commands. It will fail if Network Manager is not running. See LP: #2022023
  * d/network-manager.preinst: use /var/lib/NetworkManager for backups
    /root is not a system directory so we shouldn't use it. It might not
    even exist or the package manager might run in a sandbox and not have
    access to it. See LP: #2021937

 -- Danilo Egea Gondolfo <email address hidden> Thu, 01 Jun 2023 15:17:57 +0100