Ubuntu 24.04 and Bubblewrap

When using Bubblewrap (the bwrap command) to create a container in Ubuntu 24.04 you can expect to get one of the following error messages:

bwrap: loopback: Failed RTM_NEWADDR: Operation not permitted
bwrap: setting up uid map: Permission denied

This is due to Ubuntu developers deciding to use Apparmor to restrict the creation of user namespaces. Here is a Ubuntu blog post about it [1].

To resolve that you could upgrade to SE Linux, but the other option is to create a file named /etc/apparmor.d/bwrap with the following contents:

abi <abi/4.0>,
include <tunables/global>

profile bwrap /usr/bin/bwrap flags=(unconfined) {
  userns,

  # Site-specific additions and overrides. See local/README for details.
  include if exists <local/bwrap>
}

Then run “systemctl reload apparmor“.

• [1] https://ubuntu.com/blog/ubuntu-23-10-restricted-unprivileged-user-namespaces