net: Add Open vSwitch kernel components.

Open vSwitch is a multilayer Ethernet switch targeted at virtualized
environments.  In addition to supporting a variety of features
expected in a traditional hardware switch, it enables fine-grained
programmatic extension and flow-based control of the network.
This control is useful in a wide variety of applications but is
particularly important in multi-server virtualization deployments,
which are often characterized by highly dynamic endpoints and the need
to maintain logical abstractions for multiple tenants.

The Open vSwitch datapath provides an in-kernel fast path for packet
forwarding.  It is complemented by a userspace daemon, ovs-vswitchd,
which is able to accept configuration from a variety of sources and
translate it into packet processing rules.

See http://openvswitch.org for more information and userspace
utilities.

Signed-off-by: Jesse Gross <jesse@nicira.com>

net/openvswitch/vport-netdev.c

@@ -0,0 +1,198 @@
+/*
+ * Copyright (c) 2007-2011 Nicira Networks.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/if_arp.h>
+#include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
+#include <linux/kernel.h>
+#include <linux/llc.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+
+#include <net/llc.h>
+
+#include "datapath.h"
+#include "vport-internal_dev.h"
+#include "vport-netdev.h"
+
+/* Must be called with rcu_read_lock. */
+static void netdev_port_receive(struct vport *vport, struct sk_buff *skb)
+{
+	if (unlikely(!vport)) {
+		kfree_skb(skb);
+		return;
+	}
+
+	/* Make our own copy of the packet.  Otherwise we will mangle the
+	 * packet for anyone who came before us (e.g. tcpdump via AF_PACKET).
+	 * (No one comes after us, since we tell handle_bridge() that we took
+	 * the packet.) */
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (unlikely(!skb))
+		return;
+
+	skb_push(skb, ETH_HLEN);
+	ovs_vport_receive(vport, skb);
+}
+
+/* Called with rcu_read_lock and bottom-halves disabled. */
+static rx_handler_result_t netdev_frame_hook(struct sk_buff **pskb)
+{
+	struct sk_buff *skb = *pskb;
+	struct vport *vport;
+
+	if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
+		return RX_HANDLER_PASS;
+
+	vport = ovs_netdev_get_vport(skb->dev);
+
+	netdev_port_receive(vport, skb);
+
+	return RX_HANDLER_CONSUMED;
+}
+
+static struct vport *netdev_create(const struct vport_parms *parms)
+{
+	struct vport *vport;
+	struct netdev_vport *netdev_vport;
+	int err;
+
+	vport = ovs_vport_alloc(sizeof(struct netdev_vport),
+				&ovs_netdev_vport_ops, parms);
+	if (IS_ERR(vport)) {
+		err = PTR_ERR(vport);
+		goto error;
+	}
+
+	netdev_vport = netdev_vport_priv(vport);
+
+	netdev_vport->dev = dev_get_by_name(&init_net, parms->name);
+	if (!netdev_vport->dev) {
+		err = -ENODEV;
+		goto error_free_vport;
+	}
+
+	if (netdev_vport->dev->flags & IFF_LOOPBACK ||
+	    netdev_vport->dev->type != ARPHRD_ETHER ||
+	    ovs_is_internal_dev(netdev_vport->dev)) {
+		err = -EINVAL;
+		goto error_put;
+	}
+
+	err = netdev_rx_handler_register(netdev_vport->dev, netdev_frame_hook,
+					 vport);
+	if (err)
+		goto error_put;
+
+	dev_set_promiscuity(netdev_vport->dev, 1);
+	netdev_vport->dev->priv_flags |= IFF_OVS_DATAPATH;
+
+	return vport;
+
+error_put:
+	dev_put(netdev_vport->dev);
+error_free_vport:
+	ovs_vport_free(vport);
+error:
+	return ERR_PTR(err);
+}
+
+static void netdev_destroy(struct vport *vport)
+{
+	struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
+
+	netdev_vport->dev->priv_flags &= ~IFF_OVS_DATAPATH;
+	netdev_rx_handler_unregister(netdev_vport->dev);
+	dev_set_promiscuity(netdev_vport->dev, -1);
+
+	synchronize_rcu();
+
+	dev_put(netdev_vport->dev);
+	ovs_vport_free(vport);
+}
+
+const char *ovs_netdev_get_name(const struct vport *vport)
+{
+	const struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
+	return netdev_vport->dev->name;
+}
+
+int ovs_netdev_get_ifindex(const struct vport *vport)
+{
+	const struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
+	return netdev_vport->dev->ifindex;
+}
+
+static unsigned packet_length(const struct sk_buff *skb)
+{
+	unsigned length = skb->len - ETH_HLEN;
+
+	if (skb->protocol == htons(ETH_P_8021Q))
+		length -= VLAN_HLEN;
+
+	return length;
+}
+
+static int netdev_send(struct vport *vport, struct sk_buff *skb)
+{
+	struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
+	int mtu = netdev_vport->dev->mtu;
+	int len;
+
+	if (unlikely(packet_length(skb) > mtu && !skb_is_gso(skb))) {
+		if (net_ratelimit())
+			pr_warn("%s: dropped over-mtu packet: %d > %d\n",
+				ovs_dp_name(vport->dp), packet_length(skb), mtu);
+		goto error;
+	}
+
+	if (unlikely(skb_warn_if_lro(skb)))
+		goto error;
+
+	skb->dev = netdev_vport->dev;
+	len = skb->len;
+	dev_queue_xmit(skb);
+
+	return len;
+
+error:
+	kfree_skb(skb);
+	ovs_vport_record_error(vport, VPORT_E_TX_DROPPED);
+	return 0;
+}
+
+/* Returns null if this device is not attached to a datapath. */
+struct vport *ovs_netdev_get_vport(struct net_device *dev)
+{
+	if (likely(dev->priv_flags & IFF_OVS_DATAPATH))
+		return (struct vport *)
+			rcu_dereference_rtnl(dev->rx_handler_data);
+	else
+		return NULL;
+}
+
+const struct vport_ops ovs_netdev_vport_ops = {
+	.type		= OVS_VPORT_TYPE_NETDEV,
+	.create		= netdev_create,
+	.destroy	= netdev_destroy,
+	.get_name	= ovs_netdev_get_name,
+	.get_ifindex	= ovs_netdev_get_ifindex,
+	.send		= netdev_send,
+};