Re: Building a BSD-jail clone out of namespaces
From: Chris Webb
Date: Fri Jun 07 2013 - 08:58:58 EST
"Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> writes:
> It is a wider issue. Capabilities cover most of places in the kernel
> where the kernel tests if you have privilege but there are other
> filesystems like devtmpsfs, and the occasional silly piece of kernel
> code that should be using capabilities but is not. Beyond the kernel
> there are files like /etc/shadow that only root is allowed to read.
>
> Which all boils down to the fact that for the inconvience of using a
> separate range of uids a lot of other problems just go away.
Hi. Thanks for the clarifications here, which make a lot of sense.
> Not being able to share the host filesystem into a container is a
> downside of the current implementation. In principle you can have an
> overlay style filesystem that munges the uids and removes this
> limitation, but that doesn't currently exist.
Yes, given the design means I can't just have an identity UID/GID mapping,
this seems like the building block I'm missing to get namespace IDs instead
of host IDs stored on disk. I imagine it might be fairly straightforward for
me to take a simple 'example' stacked filesystem like wrapfs and teach it to
map UIDs and GIDs. I'll have to take a look.
Cheers,
Chris.
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