netdev - Re: [RFC PATCH net-next 0/5] Ease netns management for userland

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Date:	Fri, 14 Dec 2012 17:13:59 +0100
From:	Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	netdev@...r.kernel.org, davem@...emloft.net, aatteka@...ira.com
Subject: Re: [RFC PATCH net-next 0/5] Ease netns management for userland

Le 13/12/2012 20:08, Eric W. Biederman a écrit :
> Nicolas Dichtel <nicolas.dichtel@...nd.com> writes:
>
>> Le 12/12/2012 22:48, Eric W. Biederman a écrit :
>>> ebiederm@...ssion.com (Eric W. Biederman) writes:
>>>
>>>> It is very wrong to presume that without context you know the reason for
>>>> the exsitence of any network namespace and that you should or even that
>>>> you can manage it.  Think of running your multi-network namespace
>>>> managing application in a container.
>>>
>>> A good example of a network namespace you don't want to mess with are
>>> the network namespaces created by vsftp and chrome for security purposes
>>> to remove any possibility of creating new connections to the network.
>>>
>> Ok, I get the point.
>>
>> A last question: from an administration point of view, is it intended to
>> not be able to monitor which netns are currently used? Like it can be done
>> for sockets, files, ...
>
> No.  The difficulty monitoring which network namespaces are being used
> is an unintended side effect.
Why is netlink a bad idea? Having a way to know all existing netns is a start
point to monitor netns, isn't it?

>
> My pending changes to /proc/<pid>/ns/net and friends that allow you to
> stat those files and compare if two network are the same network
> namespace should make that monitoring much easier.  It isn't perfect as
> there currently isn't a way to take a socket and say which network
> namespace is this socket in.  But the current solution should tell you
> what is happening most of the time.
Yes, this will give interessing infos.

> struct net allocates it's own slab type so /proc/slabinfo on a good day
> can tell you how many network namespace structures have been allocated
> and are in use.
Ok.

Nicolas
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