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, 38 insertions, 8 deletions

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index c83519b555b..0f5394c4f2f 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -15,6 +15,7 @@
 
 #include <linux/netdevice.h>
 #include <linux/if_bridge.h>
+#include <linux/netpoll.h>
 #include <net/route.h>
 
 #define BR_HASH_BITS 8
@@ -143,6 +144,10 @@ struct net_bridge_port
 #ifdef CONFIG_SYSFS
 	char				sysfs_name[IFNAMSIZ];
 #endif
+
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	struct netpoll			*np;
+#endif
 };
 
 struct br_cpu_netstats {
@@ -273,16 +278,41 @@ extern void br_dev_setup(struct net_device *dev);
 extern netdev_tx_t br_dev_xmit(struct sk_buff *skb,
 			       struct net_device *dev);
 #ifdef CONFIG_NET_POLL_CONTROLLER
-extern void br_netpoll_cleanup(struct net_device *dev);
-extern void br_netpoll_enable(struct net_bridge *br,
-			      struct net_device *dev);
-extern void br_netpoll_disable(struct net_bridge *br,
-			       struct net_device *dev);
+static inline struct netpoll_info *br_netpoll_info(struct net_bridge *br)
+{
+	return br->dev->npinfo;
+}
+
+static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
+				       struct sk_buff *skb)
+{
+	struct netpoll *np = p->np;
+
+	if (np)
+		netpoll_send_skb(np, skb);
+}
+
+extern int br_netpoll_enable(struct net_bridge_port *p);
+extern void br_netpoll_disable(struct net_bridge_port *p);
 #else
-#define br_netpoll_cleanup(br)
-#define br_netpoll_enable(br, dev)
-#define br_netpoll_disable(br, dev)
+static inline struct netpoll_info *br_netpoll_info(struct net_bridge *br)
+{
+	return NULL;
+}
+
+static inline void br_netpoll_send_skb(struct net_bridge_port *p,
+				       struct sk_buff *skb)
+{
+}
 
+static inline int br_netpoll_enable(struct net_bridge_port *p)
+{
+	return 0;
+}
+
+static inline void br_netpoll_disable(struct net_bridge_port *p)
+{
+}
 #endif
 
 /* br_fdb.c */