anyway. is there a reason this is not enabled now? all the mainstream distros hae it enabled now Fedora, RHEL/CentOS 7, Ubuntu and Debian (at least on the backported kernel)
I'd think about it, if the feature wasn't entirely useless. Despite the lack of official documentation, I found a document that described how it worked. After reading that document I concluded that the feature is a huge potential security risk with no actual benefit.
What security risk exactly? There was one that I know of, and it was fixed.
If you give me a valid use case for USER_NS, I might reconsider, but every use case I can imagine is crushed by the limitations of the implementation.
The use case is that you don't need root access to start a container. I can run Firefox with a limited view to the filesystem for example, as a normal user. Or limited view to the network, for ex. just ipv4, just ipv6, just vpn. -- damjan