vlan: deliver packets received with VLAN acceleration to network taps

When VLAN header stripping is used, packets currently bypass packet
sockets (and other network taps) completely. For locally existing
VLANs, they appear directly on the VLAN device, for unknown VLANs
they are silently dropped.

Add a new function netif_nit_deliver() to deliver incoming packets
to all network interface taps and use it in __vlan_hwaccel_rx() to
make VLAN packets visible on the underlying device.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1165,6 +1165,7 @@ extern int		netif_rx(struct sk_buff *skb);
 extern int		netif_rx_ni(struct sk_buff *skb);
 #define HAVE_NETIF_RECEIVE_SKB 1
 extern int		netif_receive_skb(struct sk_buff *skb);
+extern void		netif_nit_deliver(struct sk_buff *skb);
 extern int		dev_valid_name(const char *name);
 extern int		dev_ioctl(struct net *net, unsigned int cmd, void __user *);
 extern int		dev_ethtool(struct net *net, struct ifreq *);

net/8021q/vlan_core.c

@@ -14,6 +14,9 @@ int __vlan_hwaccel_rx(struct sk_buff *skb, struct vlan_group *grp,
 		return NET_RX_DROP;
 	}
 
+	skb->vlan_tci = vlan_tci;
+	netif_nit_deliver(skb);
+
 	skb->dev = vlan_group_get_device(grp, vlan_tci & VLAN_VID_MASK);
 	if (skb->dev == NULL) {
 		dev_kfree_skb_any(skb);
@@ -22,6 +25,7 @@ int __vlan_hwaccel_rx(struct sk_buff *skb, struct vlan_group *grp,
 		return NET_RX_SUCCESS;
 	}
 	skb->dev->last_rx = jiffies;
+	skb->vlan_tci = 0;
 
 	stats = &skb->dev->stats;
 	stats->rx_packets++;

net/core/dev.c

@@ -2068,6 +2068,33 @@ static inline struct sk_buff *handle_ing(struct sk_buff *skb,
 }
 #endif
 
+/*
+ * 	netif_nit_deliver - deliver received packets to network taps
+ * 	@skb: buffer
+ *
+ * 	This function is used to deliver incoming packets to network
+ * 	taps. It should be used when the normal netif_receive_skb path
+ * 	is bypassed, for example because of VLAN acceleration.
+ */
+void netif_nit_deliver(struct sk_buff *skb)
+{
+	struct packet_type *ptype;
+
+	if (list_empty(&ptype_all))
+		return;
+
+	skb_reset_network_header(skb);
+	skb_reset_transport_header(skb);
+	skb->mac_len = skb->network_header - skb->mac_header;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(ptype, &ptype_all, list) {
+		if (!ptype->dev || ptype->dev == skb->dev)
+			deliver_skb(skb, ptype, skb->dev);
+	}
+	rcu_read_unlock();
+}
+
 /**
  *	netif_receive_skb - process receive buffer from network
  *	@skb: buffer to process