netdev - Re: [patch net-next] ipv6: allow userspace to create address with IFLA_F

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Date:	Sun, 27 Oct 2013 17:48:35 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Jiri Pirko <jiri@...nulli.us>
Cc:	Vladislav Yasevich <vyasevich@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>, kuznet@....inr.ac.ru,
	jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
	thaller@...hat.com, Stephen Hemminger <stephen@...workplumber.org>
Subject: Re: [patch net-next] ipv6: allow userspace to create address with IFLA_F_TEMPORARY flag

Hi Jiri!

On Sun, Oct 27, 2013 at 02:29:41PM +0100, Jiri Pirko wrote:
> The idea is to provide possibility to do address configuration not in
> kernel but rather in userspace (as it is done for example in NetworkManager)
> 
> Maybe I'm missing something, but why is it problem to have the
> possibility to set lifetime even for temporary prefix?

There is no problem setting the lifetime for a temporary prefix (in
contrary, it needs one) but the code paths designed for IFA_F_TEMPORARY
may not fiddle with it. This needs to be checked.

In this constellation addrconf_verify does not refresh the privacy
address when its preferred lifetime is expired, if you create the
address by only passing IFA_F_TEMPORARY to rtm_newaddr (as Vlad pointed
out). E.g. NetworkManager has to take care about that, then.

A temporary address is also bound to a non-privacy public address so
it's lifetime is determined by its lifetime (e.g. if you switch the
network and don't receive on-link information for that prefix any
more). NetworkManager would have to take care about that, too. It is
just a question of what NetworkManager wants to handle itself or lets
the kernel handle for it.

Greetings,

  Hannes

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