netdev - Re: [RFC v2 2/2] netlink: add ethernet address policy types

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Date:   Wed, 12 Sep 2018 10:50:36 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Arend van Spriel <arend.vanspriel@...adcom.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Cc:     Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [RFC v2 2/2] netlink: add ethernet address policy types

On Wed, 2018-09-12 at 10:49 +0200, Arend van Spriel wrote:
> On 9/12/2018 10:36 AM, Johannes Berg wrote:
> > From: Johannes Berg <johannes.berg@...el.com>
> > 
> > Commonly, ethernet addresses are just using a policy of
> > 	{ .len = ETH_ALEN }
> > which leaves userspace free to send more data than it should,
> > which may hide bugs.
> > 
> > Introduce NLA_ETH_ADDR which checks for exact size, and rejects
> > the attribute if the length isn't ETH_ALEN.
> > 
> > Also add NLA_ETH_ADDR_COMPAT which can be used in place of the
> > policy above, but will, in addition, warn on an address that's
> > too long.
> 
> Not sure if this is correctly described here. It seems longer addresses 
> are not rejected, but only result in a warning message. I guess the 
> problem is in the reference to the "policy above" ;-)

Yeah, good point. I meant ".len = ETH_ALEN" but should clarify that.

johannes