/usr/share/lxc/config/userns.conf is in liblxc-common 3.0.0-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | # CAP_SYS_ADMIN in init-user-ns is required for cgroup.devices
lxc.cgroup.devices.deny =
lxc.cgroup.devices.allow =
# Start with a full set of capabilities in user namespaces.
lxc.cap.drop =
lxc.cap.keep =
# We can't move bind-mounts, so don't use /dev/lxc/
lxc.tty.dir =
|