netdev - Re: [PATCH net-next] ipv6, token: allow for clearing the current device token

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Message-Id: <1460126038.1452331.572938089.68D8127C@webmail.messagingengine.com>
Date:	Fri, 08 Apr 2016 16:33:58 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Bjørn Mork <bjorn@...k.no>,
	Daniel Borkmann <daniel@...earbox.net>
Cc:	davem@...emloft.net, robbat2@...too.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] ipv6,
 token: allow for clearing the current device token



On Fri, Apr 8, 2016, at 16:18, Bjørn Mork wrote:
> Daniel Borkmann <daniel@...earbox.net> writes:
> 
> >  
> >  	if (!token)
> >  		return -EINVAL;
> > -	if (ipv6_addr_any(token))
> > -		return -EINVAL;
> >  	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP))
> >  		return -EINVAL;
> 
> Not directly related to the patch in question.  It just made me aware of
> this restriction...
> 
> I realize that I'm a few years late here, but what's with the IFF_NOARP?
> Is that just because we can't do DAD for the token based addresses?  How
> is that different from manually configuring the whole address?

IFF_NOARP is kind of the equivalent to no neighbor discovery. If you set
a token and never get in a router advertisement you never create a
tokenized ip address, thus the feature is useless.

Bye,
Hannes