/*
   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #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 <linux/spinlock.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;

  	atomic_long_t		tx_bytes;
  	atomic_long_t		tx_packets;

  	atomic_long_t		tx_dropped;

  	atomic_long_t		rx_bytes;
  	atomic_long_t		rx_packets;
  	atomic_long_t		rx_errors;

  };
  
  /* 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;
  	spinlock_t l2tp_eth_lock;
  };
  
  static inline struct l2tp_eth_net *l2tp_eth_pernet(struct net *net)
  {
  	return net_generic(net, l2tp_eth_net_id);
  }

  static struct lock_class_key l2tp_eth_tx_busylock;

  static int l2tp_eth_dev_init(struct net_device *dev)
  {
  	struct l2tp_eth *priv = netdev_priv(dev);
  
  	priv->dev = dev;

  	eth_hw_addr_random(dev);

  	memset(&dev->broadcast[0], 0xff, 6);

  	dev->qdisc_tx_busylock = &l2tp_eth_tx_busylock;

  	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));
  
  	spin_lock(&pn->l2tp_eth_lock);
  	list_del_init(&priv->list);
  	spin_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;

  	unsigned int len = skb->len;
  	int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
  
  	if (likely(ret == NET_XMIT_SUCCESS)) {
  		atomic_long_add(len, &priv->tx_bytes);
  		atomic_long_inc(&priv->tx_packets);
  	} else {
  		atomic_long_inc(&priv->tx_dropped);
  	}

  	return NETDEV_TX_OK;

  }

  static struct rtnl_link_stats64 *l2tp_eth_get_stats64(struct net_device *dev,
  						      struct rtnl_link_stats64 *stats)
  {
  	struct l2tp_eth *priv = netdev_priv(dev);
  
  	stats->tx_bytes   = atomic_long_read(&priv->tx_bytes);
  	stats->tx_packets = atomic_long_read(&priv->tx_packets);

  	stats->tx_dropped = atomic_long_read(&priv->tx_dropped);

  	stats->rx_bytes   = atomic_long_read(&priv->rx_bytes);
  	stats->rx_packets = atomic_long_read(&priv->rx_packets);
  	stats->rx_errors  = atomic_long_read(&priv->rx_errors);
  	return stats;
  }

  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,

  	.ndo_get_stats64	= l2tp_eth_get_stats64,

  };
  
  static void l2tp_eth_dev_setup(struct net_device *dev)
  {
  	ether_setup(dev);

  	dev->priv_flags		&= ~IFF_TX_SKB_SHARING;
  	dev->features		|= NETIF_F_LLTX;

  	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;

  	struct l2tp_eth *priv = netdev_priv(dev);

  
  	if (session->debug & L2TP_MSG_DATA) {
  		unsigned int length;

  
  		length = min(32u, skb->len);
  		if (!pskb_may_pull(skb, length))
  			goto error;

  		pr_debug("%s: eth recv
  ", session->name);

  		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);

  	}

  	if (!pskb_may_pull(skb, ETH_HLEN))

  		goto error;
  
  	secpath_reset(skb);
  
  	/* checksums verified by L2TP */
  	skb->ip_summed = CHECKSUM_NONE;
  
  	skb_dst_drop(skb);
  	nf_reset(skb);
  
  	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {

  		atomic_long_inc(&priv->rx_packets);
  		atomic_long_add(data_len, &priv->rx_bytes);
  	} else {
  		atomic_long_inc(&priv->rx_errors);
  	}

  	return;
  
  error:

  	atomic_long_inc(&priv->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;

  			module_put(THIS_MODULE);

  		}
  	}
  }

  #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)

  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
  ", 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) {
  		dev = dev_get_by_name(net, cfg->ifname);
  		if (dev) {
  			dev_put(dev);
  			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;

  #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)

  	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;

  	__module_get(THIS_MODULE);

  	/* Must be done after register_netdev() */
  	strlcpy(session->ifname, dev->name, IFNAMSIZ);
  
  	dev_hold(dev);
  	pn = l2tp_eth_pernet(dev_net(dev));
  	spin_lock(&pn->l2tp_eth_lock);
  	list_add(&priv->list, &pn->l2tp_eth_dev_list);
  	spin_unlock(&pn->l2tp_eth_lock);
  
  	return 0;
  
  out_del_dev:
  	free_netdev(dev);

  	spriv->dev = NULL;

  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 = net_generic(net, l2tp_eth_net_id);

  
  	INIT_LIST_HEAD(&pn->l2tp_eth_dev_list);
  	spin_lock_init(&pn->l2tp_eth_lock);

  	return 0;

  }

  static struct pernet_operations l2tp_eth_net_ops = {

  	.init = l2tp_eth_init_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;

  	pr_info("L2TP ethernet pseudowire support (L2TPv3)
  ");

  
  	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");