netdev - Re: [PATCH] bonding: fix bridged bonds in 802.3ad mode

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Message-ID: <4DB096E0.4010407@polymtl.ca>
Date:	Thu, 21 Apr 2011 16:43:12 -0400
From:	Benjamin Poirier <benjamin.poirier@...ymtl.ca>
To:	Ben Hutchings <bhutchings@...arflare.com>
CC:	Jiri Bohac <jbohac@...e.cz>, netdev@...r.kernel.org,
	Stephen Hemminger <shemminger@...ux-foundation.org>,
	Jay Vosburgh <fubar@...ibm.com>,
	Andy Gospodarek <andy@...yhouse.net>
Subject: Re: [PATCH] bonding: fix bridged bonds in 802.3ad mode

On 21/04/11 03:08 PM, Ben Hutchings wrote:
> On Thu, 2011-04-21 at 20:47 +0200, Jiri Bohac wrote:
>> 802.3ad bonding inside a bridge is broken again. Originally fixed by
>> 43aa1920117801fe9ae3d1fad886b62511e09bee, the bug was re-introduced by
>> 1e253c3b8a1aeed51eef6fc366812f219b97de65.
>>
>> LACP frames must not have their skb->dev changed by the bridging hook.
>>
>> Signed-off-by: Jiri Bohac <jbohac@...e.cz>
>>
>> --- a/drivers/net/bonding/bond_main.c
>> +++ b/drivers/net/bonding/bond_main.c
>> @@ -1514,6 +1514,11 @@ static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
>>  		memcpy(eth_hdr(skb)->h_dest, bond->dev->dev_addr, ETH_ALEN);
>>  	}
>>  
>> +	/* prevent bridging code from mangling and forwarding LACP frames */
>> +	if (bond->params.mode == BOND_MODE_8023AD &&
>> +	    skb->protocol == htons(ETH_P_SLOW))
>> +		return RX_HANDLER_PASS;
>> +
>>  	return RX_HANDLER_ANOTHER;
>>  }
>>  
> 
> It seems to me that 1e253c3b8a1aeed51eef6fc366812f219b97de65 is bogus

You bet, it's rubbish ;)

Any thoughts on how we could support a transparent bridging
configuration without repurposing br->stp_enabled or adding another
option to bridge-utils?

btw, the particular scenario I was trying to address is a virtual
machine bridged to an ethernet interface connected to a switch port with
802.1x enabled.

-Benjamin

> and should be reverted, rather than worked around by other drivers.  We
> shouldn't enable non-conformant forwarding behaviour by default just
> because some people find it useful.  The administrator should have to
> explicitly enable it.
> 
> Ben.
> 

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