netdev - Re: [PATCH net-next] bridge: allow local delivery when port is disabled

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Message-Id: <20131212.235228.1750048814040164603.davem@davemloft.net>
Date:	Thu, 12 Dec 2013 23:52:28 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	stephen@...workplumber.org
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] bridge: allow local delivery when port is
 disabled

From: Stephen Hemminger <stephen@...workplumber.org>
Date: Thu, 12 Dec 2013 15:05:23 -0800

> On Thu, 12 Dec 2013 17:26:37 -0500 (EST)
> David Miller <davem@...emloft.net> wrote:
> 
>> From: Stephen Hemminger <stephen@...workplumber.org>
>> Date: Thu, 12 Dec 2013 13:41:59 -0800
>> 
>> > When an Ethernet device is enslaved to a bridge, and the bridge STP
>> > detects loss of carrier (or operational state down), then normally
>> > packet reception is blocked.
>> > 
>> > This breaks control applications like WPA which maybe expecting to
>> > receive packets to negotiate to bring link up. The bridge needs to
>> > block forwarding packets from these disabled ports, but there is no
>> > hard requirement to not allow local packet delivery.
>> > 
>> > In this special case, packets are not forwarded (local delivery only),
>> > and only packet directed at the address of the Ethernet device are
>> > accepted (no promiscuous or other ports in bridge).
>> > 
>> > The existing code already allowed link-local-address packets in
>> > which is what STP uses to communicate with other bridges.
>> > 
>> > Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
>> > Signed-off-by: Felix Fietkau <nbd@...nwrt.org>
>> 
>> I think this change needs to be more careful about the setting of
>> *pskb.  It should not be assigned if we return RX_HANDLER_CONSUMED.
> 
> It was already in the existing code path for link local.

That's not true, the "*pskb = skb;" assignment was only done when the
code retuned RX_HANDLER_PASS.  You are changing it to unconditionally
make this assignment.

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