[NET]: Virtual ethernet device driver.

Veth stands for Virtual ETHernet. It is a simple tunnel driver
that works at the link layer and looks like a pair of ethernet
devices interconnected with each other.

Mainly it allows to communicate between network namespaces but
it can be used as is as well.

The newlink callback is organized that way to make it easy to
create the peer device in the separate namespace when we have
them in kernel.

This implementation uses another interface - the RTM_NRELINK
message introduced by Patric.

Bug fixes from Daniel Lezcano.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/Kconfig

@@ -135,6 +135,12 @@ config TUN
 
 	  If you don't know what to use this for, you don't need it.
 
+config VETH
+	tristate "Virtual ethernet device"
+	---help---
+	  The device is an ethernet tunnel. Devices are created in pairs. When
+	  one end receives the packet it appears on its pair and vice versa.
+
 config NET_SB1000
 	tristate "General Instruments Surfboard 1000"
 	depends on PNP

drivers/net/Makefile

@@ -193,6 +193,7 @@ obj-$(CONFIG_MACSONIC) += macsonic.o
 obj-$(CONFIG_MACMACE) += macmace.o
 obj-$(CONFIG_MAC89x0) += mac89x0.o
 obj-$(CONFIG_TUN) += tun.o
+obj-$(CONFIG_VETH) += veth.o
 obj-$(CONFIG_NET_NETX) += netx-eth.o
 obj-$(CONFIG_DL2K) += dl2k.o
 obj-$(CONFIG_R8169) += r8169.o