Update on the previous comment, I realised the issue was the the partition where /var was mounted to hat nosuid set. Seems /var/lib/lxc must allow for the suid bit to be set. The problem is that people often have /home mounted with nosuid as a normal security precaution, so this effects running unprivileged containers as well.
Update on the previous comment, I realised the issue was the the partition where /var was mounted to hat nosuid set. Seems /var/lib/lxc must allow for the suid bit to be set. The problem is that people often have /home mounted with nosuid as a normal security precaution, so this effects running unprivileged containers as well.