netdev - Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+

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Date:	Wed, 05 Oct 2011 23:36:43 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ben Greear <greearb@...delatech.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: IPv4 multicast and mac-vlans acting weird on 3.0.4+

Le mercredi 05 octobre 2011 à 13:56 -0700, Ben Greear a écrit :

> Wouldn't you have the same problem with two real Ethernet interfaces on
> the same LAN, or two 802.1Q devices for that matter?  The addrs will all
> be the same in that case too?
> 

Usually multicast is coupled with routing.

A JOIN message from your app wont be sent on all interfaces...

But yes, we might have a similar issue with regular vlans.

Probably nobody noticed yet. Just say no to fragments :)

> Also, if I have just a single mac-vlan active (the other 3 are 'ifconfig foo down'),
> I still see the problem with mcast.
> 

Thats another bug : macvlan doesnt test IFF_UP on broadcasts, only for
unicast messages. Please test following patch.

>  From what you describe, I am thinking I may be hitting a different
> issue.  Any ideas on how to figure out why exactly the NF_HOOK isn't
> calling the ip_rcv_finish method?
> 

Really I believe I tried to explain the thing already...

ip_local_deliver() -> ip_defrag() :


[PATCH] macvlan: dont send frames on DOWN devices

Reported-by: Ben Greear <greearb@...delatech.com>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index b100c90..94a0282 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -145,7 +145,8 @@ static void macvlan_broadcast(struct sk_buff *skb,
 		hlist_for_each_entry_rcu(vlan, n, &port->vlan_hash[i], hlist) {
 			if (vlan->dev == src || !(vlan->mode & mode))
 				continue;
-
+			if (!(vlan->dev->flags & IFF_UP))
+				continue;
 			nskb = skb_clone(skb, GFP_ATOMIC);
 			err = macvlan_broadcast_one(nskb, vlan, eth,
 					 mode == MACVLAN_MODE_BRIDGE);


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