David Howells <dhowells@xxxxxxxxxx> writes: > Another thing that could be useful is a list of what device files a container > may access, so that we can allow limited mounting by the container root user > within the container. That is totally not why that isn't allowed, and won't be allowed any time soon. The issue is that the filesystem implementations in the kernel are not prepared to handle hostile filesystem data structures so that that is the definition of a kernel exploit. The attack surface of the kernel gets quite a bit larger in that case. Perhaps if all of the filesystems data structures had a hmac on them we could allow something like this. Once we can make it safe it is easy to add an appropriate interface. We most defintiely don't need a ``container'' data structure in the kernel to do that. A completely unprivileged fuse is much more likely to work for this use case. And we do already have have the device cgroup which sort of does this. Eric
