bridge: Fix netpoll support

There are multiple problems with the newly added netpoll support:

1) Use-after-free on each netpoll packet.
2) Invoking unsafe code on netpoll/IRQ path.
3) Breaks when netpoll is enabled on the underlying device.

This patch fixes all of these problems.  In particular, we now
allocate proper netpoll structures for each underlying device.

We only allow netpoll to be enabled on the bridge when all the
devices underneath it support netpoll.  Once it is enabled, we
do not allow non-netpoll devices to join the bridge (until netpoll
is disabled again).

This allows us to do away with the npinfo juggling that caused
problem number 1.

Incidentally this patch fixes number 2 by bypassing unsafe code
such as multicast snooping and netfilter.

Reported-by: Qianfeng Zhang <frzhang@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 22 deletions

diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index a98ef1393097..6e97711fd2c5 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -50,14 +50,7 @@ int br_dev_queue_push_xmit(struct sk_buff *skb)
 			kfree_skb(skb);
 		else {
 			skb_push(skb, ETH_HLEN);
-
-#ifdef CONFIG_NET_POLL_CONTROLLER
-			if (unlikely(skb->dev->priv_flags & IFF_IN_NETPOLL)) {
-				netpoll_send_skb(skb->dev->npinfo->netpoll, skb);
-				skb->dev->priv_flags &= ~IFF_IN_NETPOLL;
-			} else
-#endif
-				dev_queue_xmit(skb);
+			dev_queue_xmit(skb);
 		}
 	}
 
@@ -73,23 +66,20 @@ int br_forward_finish(struct sk_buff *skb)
 
 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 {
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	struct net_bridge *br = to->br;
-	if (unlikely(br->dev->priv_flags & IFF_IN_NETPOLL)) {
-		struct netpoll *np;
-		to->dev->npinfo = skb->dev->npinfo;
-		np = skb->dev->npinfo->netpoll;
-		np->real_dev = np->dev = to->dev;
-		to->dev->priv_flags |= IFF_IN_NETPOLL;
-	}
-#endif
 	skb->dev = to->dev;
+
+	if (unlikely(netpoll_tx_running(to->dev))) {
+		if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
+			kfree_skb(skb);
+		else {
+			skb_push(skb, ETH_HLEN);
+			br_netpoll_send_skb(to, skb);
+		}
+		return;
+	}
+
 	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 		br_forward_finish);
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	if (skb->dev->npinfo)
-		skb->dev->npinfo->netpoll->dev = br->dev;
-#endif
 }
 
 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)