[10/12] l2tp: Add L2TP ethernet pseudowire support

diff --git a/net/l2tp/Kconfig b/net/l2tp/Kconfig
index edc2c6e..9cfca8f 100644
--- a/net/l2tp/Kconfig
+++ b/net/l2tp/Kconfig
@@ -69,3 +69,27 @@  config L2TP_IP
 	  To compile this driver as a module, choose M here. The module
 	  will be called l2tp_ip.
 
+config L2TP_ETH
+	tristate "L2TP ethernet pseudowire support for L2TPv3"
+	depends on L2TP_V3
+	help
+	  Support for carrying raw ethernet frames over L2TPv3.
+
+	  From RFC 4719 <http://www.ietf.org/rfc/rfc4719.txt>.
+
+	  The Layer 2 Tunneling Protocol, Version 3 (L2TPv3) can be
+   	  used as a control protocol and for data encapsulation to set
+   	  up Pseudowires for transporting layer 2 Packet Data Units
+   	  across an IP network [RFC3931].
+
+	  This driver provides an ethernet virtual interface for each
+	  L2TP ethernet pseudowire instance. Standard Linux tools may
+	  be used to assign an IP address to the local virtual
+	  interface, or add the interface to a bridge.
+
+	  If you are using L2TPv3, you will almost certainly want to
+	  enable this option.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called l2tp_eth.
+
diff --git a/net/l2tp/Makefile b/net/l2tp/Makefile
index 2c4a14b..bddbf04 100644
--- a/net/l2tp/Makefile
+++ b/net/l2tp/Makefile
@@ -8,3 +8,4 @@  obj-$(CONFIG_L2TP) += l2tp_core.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_IP)) += l2tp_ip.o
 obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_V3)) += l2tp_netlink.o
+obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_L2TP_ETH)) += l2tp_eth.o
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
new file mode 100644
index 0000000..8b87280
--- /dev/null
+++ b/net/l2tp/l2tp_eth.c
@@ -0,0 +1,383 @@ 
+/*
+ * L2TPv3 ethernet pseudowire driver
+ *
+ * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/socket.h>
+#include <linux/hash.h>
+#include <linux/l2tp.h>
+#include <linux/in.h>
+#include <linux/etherdevice.h>
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/icmp.h>
+#include <net/udp.h>
+#include <net/inet_common.h>
+#include <net/inet_hashtables.h>
+#include <net/tcp_states.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+
+#include "l2tp_core.h"
+
+/* Default device name. May be overridden by name specified by user */
+#define L2TP_ETH_DEV_NAME	"l2tpeth%d"
+
+/* via netdev_priv() */
+struct l2tp_eth {
+	struct net_device	*dev;
+	struct sock		*tunnel_sock;
+	struct l2tp_session	*session;
+	struct list_head	list;
+};
+
+/* via l2tp_session_priv() */
+struct l2tp_eth_sess {
+	struct net_device	*dev;
+};
+
+/* per-net private data for this module */
+static unsigned int l2tp_eth_net_id;
+struct l2tp_eth_net {
+	struct list_head l2tp_eth_dev_list;
+	rwlock_t l2tp_eth_lock;
+};
+
+static inline struct l2tp_eth_net *l2tp_eth_pernet(struct net *net)
+{
+	BUG_ON(!net);
+
+	return net_generic(net, l2tp_eth_net_id);
+}
+
+static struct l2tp_session *l2tp_eth_session_find_by_ifname(struct net *net, char *ifname)
+{
+	struct net_device *dev;
+
+	dev = dev_get_by_name(net, ifname);
+	if (dev) {
+		struct l2tp_eth *priv = netdev_priv(dev);
+		return priv->session;
+	}
+
+	return NULL;
+}
+
+static int l2tp_eth_dev_init(struct net_device *dev)
+{
+	struct l2tp_eth *priv = netdev_priv(dev);
+	struct l2tp_session *session = priv->session;
+	__be32 sid = htonl(session->session_id);
+
+	priv->dev = dev;
+
+	/* Derive a MAC address for the new interface. We use the L2TP
+	 * session's session-id to guarantee a system-wide unique
+	 * address. This MAC is only visible within the L2TP session.
+	 */
+	dev->dev_addr[0] = 0x02; /* IEEE 802 local */
+	dev->dev_addr[1] = 'L';
+	memcpy(&dev->dev_addr[2], &sid, 4);
+	memset(&dev->broadcast[0], 0xff, 6);
+
+	return 0;
+}
+
+static void l2tp_eth_dev_uninit(struct net_device *dev)
+{
+	struct l2tp_eth *priv = netdev_priv(dev);
+	struct l2tp_eth_net *pn = l2tp_eth_pernet(dev_net(dev));
+
+	write_lock(&pn->l2tp_eth_lock);
+	list_del_init(&priv->list);
+	write_unlock(&pn->l2tp_eth_lock);
+	dev_put(dev);
+}
+
+static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct l2tp_eth *priv = netdev_priv(dev);
+	struct l2tp_session *session = priv->session;
+
+	l2tp_xmit_skb(session, skb, session->hdr_len);
+
+	dev->stats.tx_bytes += skb->len;
+	dev->stats.tx_packets++;
+
+	return 0;
+}
+
+static struct net_device_ops l2tp_eth_netdev_ops = {
+	.ndo_init		= l2tp_eth_dev_init,
+	.ndo_uninit		= l2tp_eth_dev_uninit,
+	.ndo_start_xmit		= l2tp_eth_dev_xmit,
+};
+
+static void l2tp_eth_dev_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+
+	dev->netdev_ops		= &l2tp_eth_netdev_ops;
+	dev->destructor		= free_netdev;
+}
+
+static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
+{
+	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
+	struct net_device *dev = spriv->dev;
+
+	if (session->debug & L2TP_MSG_DATA) {
+		unsigned int length;
+		int offset;
+		u8 *ptr = skb->data;
+
+		length = min(32u, skb->len);
+		if (!pskb_may_pull(skb, length))
+			goto error;
+
+		printk(KERN_DEBUG "%s: eth recv: ", session->name);
+
+		offset = 0;
+		do {
+			printk(" %02X", ptr[offset]);
+		} while (++offset < length);
+
+		printk("\n");
+	}
+
+	if (data_len < ETH_HLEN)
+		goto error;
+
+	secpath_reset(skb);
+
+	skb->protocol = eth_type_trans(skb, dev);
+
+	dev->last_rx = jiffies;
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += data_len;
+
+	/* checksums verified by L2TP */
+	skb->ip_summed = CHECKSUM_NONE;
+
+	skb_dst_drop(skb);
+	nf_reset(skb);
+	netif_receive_skb(skb);
+
+	return;
+
+error:
+	dev->stats.rx_errors++;
+	kfree_skb(skb);
+}
+
+static void l2tp_eth_delete(struct l2tp_session *session)
+{
+	struct l2tp_eth_sess *spriv;
+	struct net_device *dev;
+
+	if (session) {
+		spriv = l2tp_session_priv(session);
+		dev = spriv->dev;
+		if (dev) {
+			unregister_netdev(dev);
+			spriv->dev = NULL;
+		}
+	}
+}
+
+#ifdef CONFIG_PROC_FS
+static void l2tp_eth_show(struct seq_file *m, void *arg)
+{
+	struct l2tp_session *session = arg;
+	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
+	struct net_device *dev = spriv->dev;
+
+	seq_printf(m, "   interface %s\n", dev->name);
+}
+#endif
+
+static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
+{
+	struct net_device *dev;
+	char name[IFNAMSIZ];
+	struct l2tp_tunnel *tunnel;
+	struct l2tp_session *session;
+	struct l2tp_eth *priv;
+	struct l2tp_eth_sess *spriv;
+	int rc;
+	struct l2tp_eth_net *pn;
+
+	tunnel = l2tp_tunnel_find(net, tunnel_id);
+	if (!tunnel) {
+		rc = -ENODEV;
+		goto out;
+	}
+
+	session = l2tp_session_find(net, tunnel, session_id);
+	if (session) {
+		rc = -EEXIST;
+		goto out;
+	}
+
+	if (cfg->ifname) {
+		session = l2tp_eth_session_find_by_ifname(net, cfg->ifname);
+		if (session) {
+			rc = -EEXIST;
+			goto out;
+		}
+		strlcpy(name, cfg->ifname, IFNAMSIZ);
+	} else
+		strcpy(name, L2TP_ETH_DEV_NAME);
+
+	session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
+				      peer_session_id, cfg);
+	if (!session) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	dev = alloc_netdev(sizeof(*priv), name, l2tp_eth_dev_setup);
+	if (!dev) {
+		rc = -ENOMEM;
+		goto out_del_session;
+	}
+
+	dev_net_set(dev, net);
+	if (session->mtu == 0)
+		session->mtu = dev->mtu - session->hdr_len;
+	dev->mtu = session->mtu;
+	dev->needed_headroom += session->hdr_len;
+
+	priv = netdev_priv(dev);
+	priv->dev = dev;
+	priv->session = session;
+	INIT_LIST_HEAD(&priv->list);
+
+	priv->tunnel_sock = tunnel->sock;
+	session->recv_skb = l2tp_eth_dev_recv;
+	session->session_close = l2tp_eth_delete;
+#ifdef CONFIG_PROC_FS
+	session->show = l2tp_eth_show;
+#endif
+
+	spriv = l2tp_session_priv(session);
+	spriv->dev = dev;
+
+	rc = register_netdev(dev);
+	if (rc < 0)
+		goto out_del_dev;
+
+	/* Must be done after register_netdev() */
+	strlcpy(session->ifname, dev->name, IFNAMSIZ);
+
+	dev_hold(dev);
+	pn = l2tp_eth_pernet(dev_net(dev));
+	write_lock(&pn->l2tp_eth_lock);
+	list_add(&priv->list, &pn->l2tp_eth_dev_list);
+	write_unlock(&pn->l2tp_eth_lock);
+
+	return 0;
+
+out_del_dev:
+	free_netdev(dev);
+out_del_session:
+	l2tp_session_delete(session);
+out:
+	return rc;
+}
+
+static __net_init int l2tp_eth_init_net(struct net *net)
+{
+	struct l2tp_eth_net *pn;
+	int err;
+
+	pn = kzalloc(sizeof(*pn), GFP_KERNEL);
+	if (!pn)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&pn->l2tp_eth_dev_list);
+	rwlock_init(&pn->l2tp_eth_lock);
+
+	err = net_assign_generic(net, l2tp_eth_net_id, pn);
+	if (err)
+		goto out;
+
+	return 0;
+
+out:
+	kfree(pn);
+	return err;
+}
+
+static __net_exit void l2tp_eth_exit_net(struct net *net)
+{
+	struct l2tp_eth_net *pn;
+
+	pn = net_generic(net, l2tp_eth_net_id);
+	/*
+	 * if someone has cached our net then
+	 * further net_generic call will return NULL
+	 */
+	net_assign_generic(net, l2tp_eth_net_id, NULL);
+	kfree(pn);
+}
+
+static __net_initdata struct pernet_operations l2tp_eth_net_ops = {
+	.init = l2tp_eth_init_net,
+	.exit = l2tp_eth_exit_net,
+	.id   = &l2tp_eth_net_id,
+	.size = sizeof(struct l2tp_eth_net),
+};
+
+
+static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
+	.session_create	= l2tp_eth_create,
+	.session_delete	= l2tp_session_delete,
+};
+
+
+static int __init l2tp_eth_init(void)
+{
+	int err = 0;
+
+	err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
+	if (err)
+		goto out;
+
+	err = register_pernet_device(&l2tp_eth_net_ops);
+	if (err)
+		goto out_unreg;
+
+	printk(KERN_INFO "L2TP ethernet pseudowire support (L2TPv3)\n");
+
+	return 0;
+
+out_unreg:
+	l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
+out:
+	return err;
+}
+
+static void __exit l2tp_eth_exit(void)
+{
+	unregister_pernet_device(&l2tp_eth_net_ops);
+	l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
+}
+
+module_init(l2tp_eth_init);
+module_exit(l2tp_eth_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
+MODULE_VERSION("1.0");