3 files changed, 45 insertions, 14 deletions

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 2d657f2314cb..6c4b5a2d7877 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -155,8 +155,6 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
         struct veth_net_stats *stats, *rcv_stats;
         int length, cpu;
 
-        skb_orphan(skb);
-
         priv = netdev_priv(dev);
         rcv = priv->peer;
         rcv_priv = netdev_priv(rcv);
@@ -168,20 +166,12 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
         if (!(rcv->flags & IFF_UP))
                 goto tx_drop;
 
-        if (skb->len > (rcv->mtu + MTU_PAD))
-                goto rx_drop;
-
-        skb->tstamp.tv64 = 0;
-        skb->pkt_type = PACKET_HOST;
-        skb->protocol = eth_type_trans(skb, rcv);
         if (dev->features & NETIF_F_NO_CSUM)
                 skb->ip_summed = rcv_priv->ip_summed;
 
-        skb->mark = 0;
-        secpath_reset(skb);
-        nf_reset(skb);
-
-        length = skb->len;
+        length = skb->len + ETH_HLEN;
+        if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS)
+                goto rx_drop;
 
         stats->tx_bytes += length;
         stats->tx_packets++;
@@ -189,7 +179,6 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
         rcv_stats->rx_bytes += length;
         rcv_stats->rx_packets++;
 
-        netif_rx(skb);
         return NETDEV_TX_OK;
 
 tx_drop:
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 97873e31661c..9428793775a0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1562,6 +1562,8 @@ extern int		dev_set_mac_address(struct net_device *,
 extern int              dev_hard_start_xmit(struct sk_buff *skb,
                                             struct net_device *dev,
                                             struct netdev_queue *txq);
+extern int              dev_forward_skb(struct net_device *dev,
+                                        struct sk_buff *skb);
 
 extern int              netdev_budget;
 
diff --git a/net/core/dev.c b/net/core/dev.c
index e65af6041415..7775e8b48deb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -105,6 +105,7 @@
 #include <net/dst.h>
 #include <net/pkt_sched.h>
 #include <net/checksum.h>
+#include <net/xfrm.h>
 #include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/kmod.h>
@@ -1419,6 +1420,45 @@ static inline void net_timestamp(struct sk_buff *skb)
                 skb->tstamp.tv64 = 0;
 }
 
+/**
+ * dev_forward_skb - loopback an skb to another netif
+ *
+ * @dev: destination network device
+ * @skb: buffer to forward
+ *
+ * return values:
+ *      NET_RX_SUCCESS  (no congestion)
+ *      NET_RX_DROP     (packet was dropped)
+ *
+ * dev_forward_skb can be used for injecting an skb from the
+ * start_xmit function of one device into the receive queue
+ * of another device.
+ *
+ * The receiving device may be in another namespace, so
+ * we have to clear all information in the skb that could
+ * impact namespace isolation.
+ */
+int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
+{
+        skb_orphan(skb);
+
+        if (!(dev->flags & IFF_UP))
+                return NET_RX_DROP;
+
+        if (skb->len > (dev->mtu + dev->hard_header_len))
+                return NET_RX_DROP;
+
+        skb_dst_drop(skb);
+        skb->tstamp.tv64 = 0;
+        skb->pkt_type = PACKET_HOST;
+        skb->protocol = eth_type_trans(skb, dev);
+        skb->mark = 0;
+        secpath_reset(skb);
+        nf_reset(skb);
+        return netif_rx(skb);
+}
+EXPORT_SYMBOL_GPL(dev_forward_skb);
+
 /*
  *      Support routine. Sends outgoing frames to any network
  *      taps currently in use.