This is invalid. It actually all still works because: udev hook /lib/udev/rules.d/80-ifupdown.rules calls /lib/udev/ifupdown-hotplug which calls systemctl --no-block start $(systemd-escape --template ifup@.service $INTERFACE)
Then the ifup@.service is what actually brings up the device. That service is then not beholden to the udevadm restrcitions. ** Changed in: ifupdown (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ifupdown in Ubuntu. https://bugs.launchpad.net/bugs/1792168 Title: ifupdown hotplug dhcp fails due to udevadm RestrictAddressFamilies Status in ifupdown package in Ubuntu: Invalid Bug description: I haven't verified this, but I believe that ifupdown works through udevadm hooks. So udevadm hotplug event -> ifup eth0. Any subprocesses of a udevadm hook will be restricted by the systemd-udevd.service restrictions, which currently are RestrictAddressFamilies=AF_UNIX AF_NETLINK AF_INET AF_INET6 We found this when playing with udevamd hooks to bring up network devices on cosmic (netplan). root@b1:~# systemctl cat udev.service # /lib/systemd/system/systemd-udevd.service # SPDX-License-Identifier: LGPL-2.1+ # # This file is part of systemd. # # systemd is free software; you can redistribute it and/or modify it # under the terms of the GNU Lesser General Public License as published by # the Free Software Foundation; either version 2.1 of the License, or # (at your option) any later version. [Unit] Description=udev Kernel Device Manager Documentation=man:systemd-udevd.service(8) man:udev(7) DefaultDependencies=no After=systemd-sysusers.service systemd-hwdb-update.service Before=sysinit.target ConditionPathIsReadWrite=/sys [Service] Type=notify OOMScoreAdjust=-1000 Sockets=systemd-udevd-control.socket systemd-udevd-kernel.socket Restart=always RestartSec=0 ExecStart=/lib/systemd/systemd-udevd KillMode=mixed WatchdogSec=3min TasksMax=infinity MountFlags=slave MemoryDenyWriteExecute=yes RestrictRealtime=yes RestrictAddressFamilies=AF_UNIX AF_NETLINK AF_INET AF_INET6 SystemCallArchitectures=native LockPersonality=yes IPAddressDeny=any ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: ifupdown 0.8.17ubuntu1.1 ProcVersionSignature: Ubuntu 4.17.0-9.10-generic 4.17.17 Uname: Linux 4.17.0-9-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.3 Architecture: amd64 Date: Wed Sep 12 15:09:01 2018 ProcEnviron: TERM=screen.xterm-256color PATH=(custom, no user) LANG=C.UTF-8 SourcePackage: ifupdown UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1792168/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp