Unprivileged user namespace creation is allowed an will result in a
transition into the unprivileged_userns profile. The
unprivileged_userns profile with then deny all capabilities within the
profile. Execution of applications is allowed within the
unprivileged_userns profile but, they will result in a stack with the
unprivileged_userns profile, that is to say the unprivileged_userns
profile can not be dropped (capabilities can not be gained).
If the unprivileged_userns profile does not exist, unprivileged user
namespace creation is denied as before.
Signed-off-by: Georgia Garcia <georgia.garcia@canonical.com>