Re: chroot(2) and bind mounts as non-root

[Colin Walters <walters@verbum.org>]

On Sun, 2011-12-18 at 16:55 -0800, Eric W. Biederman wrote:

> I expect by the time this makes it to "out of the box" experiences on
> enterprise distros, useradd and friends will be giving out 1000 or so uids
> to new accounts.

Hmm...how would that work?  Would it be something that would happen at
PAM time, like a module that looks up some file in /etc and says "OK
this uid gets this range" and uploads that to the kernel? 

This whole idea of a normal uid getting *other* slave uids is cool but
scary at the same time.  So much infrastructure in what I think of as
"General Purpose Linux"[1] is built up around a uid - resource
restrictions and authentication for example.

I guess as long as we're sure that all cases where a "uid" crosses a
user namespace (say socket credentials) and appears as the right thing,
it may be secure.

> I think the user namespace will do what you need. Certainly it appears
> that everything in your example binary will be allowed by the time it is
> done.

That's cool, I will keep an eye on what you guys are doing.  Looks like
the containers list on linuxfoundation.org is the right one to follow?

[1] The code that's shared between RHEL and Debian roughly between the
kernel and GNOME, discarding the pointless "packaging" differences