Re: strict isolation of net interfaces

[ebiederm@xmission.com (Eric W. Biederman)]

"Serge E. Hallyn" <serue@us.ibm.com> writes:

> Quoting Eric W. Biederman (ebiederm@xmission.com):
>> This whole debate on network devices show up in multiple network namespaces
>> is just silly.  The only reason for wanting that appears to be better
> management.
>
> A damned good reason.  

Better management is a good reason.  But constructing the management in 
a way that hampers the implementation and confuses existing applications is
a problem.

Things are much easier if namespaces are completely independent.

Among other things the semantics are clear and obvious.

> Clearly we want the parent namespace to be able
> to control what the child can do.  So whatever interface a child gets,
> the parent should be able to somehow address.  Simple iptables rules
> controlling traffic between it's own netdevice and the one it hands it's
> children seem a good option.

That or we setup the child and then drop CAP_NET_ADMIN.

>> We have deeper issues like can we do a reasonable implementation without a
>> network device showing up in multiple namespaces.
>
> Isn't that the same issue?

I guess I was thinking from the performance and cleanliness point of
view.

>> If we can get layer 2 level isolation working without measurable overhead
>> with one namespace per device it may be worth revisiting things.  Until
>> then it is a side issue at best.
>
> Ok, and in the meantime we can all use the network part of the bsdjail
> lsm?  :)

If necessary.  But mostly we concentrate on the fundamentals and figure
out what it takes to take the level 2 stuff working.

Eric