netdev - Re: How to use gretap with bridge?

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Message-ID: <20091030155148.GA8283@gondor.apana.org.au>
Date:	Fri, 30 Oct 2009 11:51:48 -0400
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"Neulinger, Nathan" <nneul@....edu>,
	"David S. Miller" <davem@...emloft.net>
Cc:	shemminger@...tta.com, netdev@...r.kernel.org
Subject: Re: How to use gretap with bridge?

Neulinger, Nathan <nneul@....edu> wrote:
>
> The above change fixes it for me, but I'm no expert on this chunk of
> code. (Perhaps it it shouldn't set dev_addr at all?)

OK, it was a stupid mistake on my part.  I added a netdev ops
struct for tap but didn't actually use it!  Please let us know
whether this patch fixes the problem.

gre: Fix dev_addr clobbering for gretap

Nathan Neulinger noticed that gretap devices get their MAC address
from the local IP address, which results in invalid MAC addresses
half of the time.

This is because gretap is still using the tunnel netdev ops rather
than the correct tap netdev ops struct.

This patch also fixes changelink to not clobber the MAC address
for the gretap case.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

Thanks,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 41ada99..1433338 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1464,7 +1464,7 @@ static void ipgre_tap_setup(struct net_device *dev)
 
 	ether_setup(dev);
 
-	dev->netdev_ops		= &ipgre_netdev_ops;
+	dev->netdev_ops		= &ipgre_tap_netdev_ops;
 	dev->destructor 	= free_netdev;
 
 	dev->iflink		= 0;
@@ -1525,25 +1525,29 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
 		if (t->dev != dev)
 			return -EEXIST;
 	} else {
-		unsigned nflags = 0;
-
 		t = nt;
 
-		if (ipv4_is_multicast(p.iph.daddr))
-			nflags = IFF_BROADCAST;
-		else if (p.iph.daddr)
-			nflags = IFF_POINTOPOINT;
+		if (dev->type != ARPHRD_ETHER) {
+			unsigned nflags = 0;
 
-		if ((dev->flags ^ nflags) &
-		    (IFF_POINTOPOINT | IFF_BROADCAST))
-			return -EINVAL;
+			if (ipv4_is_multicast(p.iph.daddr))
+				nflags = IFF_BROADCAST;
+			else if (p.iph.daddr)
+				nflags = IFF_POINTOPOINT;
+
+			if ((dev->flags ^ nflags) &
+			    (IFF_POINTOPOINT | IFF_BROADCAST))
+				return -EINVAL;
+		}
 
 		ipgre_tunnel_unlink(ign, t);
 		t->parms.iph.saddr = p.iph.saddr;
 		t->parms.iph.daddr = p.iph.daddr;
 		t->parms.i_key = p.i_key;
-		memcpy(dev->dev_addr, &p.iph.saddr, 4);
-		memcpy(dev->broadcast, &p.iph.daddr, 4);
+		if (dev->type != ARPHRD_ETHER) {
+			memcpy(dev->dev_addr, &p.iph.saddr, 4);
+			memcpy(dev->broadcast, &p.iph.daddr, 4);
+		}
 		ipgre_tunnel_link(ign, t);
 		netdev_state_change(dev);
 	}
--
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