/*
   *  drivers/net/veth.c
   *
   *  Copyright (C) 2007 OpenVZ http://openvz.org, SWsoft Inc
   *
   * Author: Pavel Emelianov <xemul@openvz.org>
   * Ethtool interface from: Eric W. Biederman <ebiederm@xmission.com>
   *
   */
  
  #include <linux/netdevice.h>
  #include <linux/slab.h>
  #include <linux/ethtool.h>
  #include <linux/etherdevice.h>
  #include <linux/u64_stats_sync.h>
  
  #include <net/dst.h>
  #include <net/xfrm.h>
  #include <linux/veth.h>
  #include <linux/module.h>
  
  #define DRV_NAME	"veth"
  #define DRV_VERSION	"1.0"
  
  #define MIN_MTU 68		/* Min L3 MTU */
  #define MAX_MTU 65535		/* Max L3 MTU (arbitrary) */
  
  struct pcpu_vstats {
  	u64			packets;
  	u64			bytes;
  	struct u64_stats_sync	syncp;
  };
  
  struct veth_priv {
  	struct net_device __rcu	*peer;
  	atomic64_t		dropped;
  };
  
  /*
   * ethtool interface
   */
  
  static struct {
  	const char string[ETH_GSTRING_LEN];
  } ethtool_stats_keys[] = {
  	{ "peer_ifindex" },
  };
  
  static int veth_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
  {
  	cmd->supported		= 0;
  	cmd->advertising	= 0;
  	ethtool_cmd_speed_set(cmd, SPEED_10000);
  	cmd->duplex		= DUPLEX_FULL;
  	cmd->port		= PORT_TP;
  	cmd->phy_address	= 0;
  	cmd->transceiver	= XCVR_INTERNAL;
  	cmd->autoneg		= AUTONEG_DISABLE;
  	cmd->maxtxpkt		= 0;
  	cmd->maxrxpkt		= 0;
  	return 0;
  }
  
  static void veth_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
  {
  	strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
  	strlcpy(info->version, DRV_VERSION, sizeof(info->version));
  }
  
  static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
  {
  	switch(stringset) {
  	case ETH_SS_STATS:
  		memcpy(buf, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
  		break;
  	}
  }
  
  static int veth_get_sset_count(struct net_device *dev, int sset)
  {
  	switch (sset) {
  	case ETH_SS_STATS:
  		return ARRAY_SIZE(ethtool_stats_keys);
  	default:
  		return -EOPNOTSUPP;
  	}
  }
  
  static void veth_get_ethtool_stats(struct net_device *dev,
  		struct ethtool_stats *stats, u64 *data)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer = rtnl_dereference(priv->peer);
  
  	data[0] = peer ? peer->ifindex : 0;
  }
  
  static const struct ethtool_ops veth_ethtool_ops = {
  	.get_settings		= veth_get_settings,
  	.get_drvinfo		= veth_get_drvinfo,
  	.get_link		= ethtool_op_get_link,
  	.get_strings		= veth_get_strings,
  	.get_sset_count		= veth_get_sset_count,
  	.get_ethtool_stats	= veth_get_ethtool_stats,
  };
  
  static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *rcv;
  	int length = skb->len;
  
  	rcu_read_lock();
  	rcv = rcu_dereference(priv->peer);
  	if (unlikely(!rcv)) {
  		kfree_skb(skb);
  		goto drop;
  	}
  	/* don't change ip_summed == CHECKSUM_PARTIAL, as that
  	 * will cause bad checksum on forwarded packets
  	 */
  	if (skb->ip_summed == CHECKSUM_NONE &&
  	    rcv->features & NETIF_F_RXCSUM)
  		skb->ip_summed = CHECKSUM_UNNECESSARY;
  
  	if (likely(dev_forward_skb(rcv, skb) == NET_RX_SUCCESS)) {
  		struct pcpu_vstats *stats = this_cpu_ptr(dev->vstats);
  
  		u64_stats_update_begin(&stats->syncp);
  		stats->bytes += length;
  		stats->packets++;
  		u64_stats_update_end(&stats->syncp);
  	} else {
  drop:
  		atomic64_inc(&priv->dropped);
  	}
  	rcu_read_unlock();
  	return NETDEV_TX_OK;
  }
  
  /*
   * general routines
   */
  
  static u64 veth_stats_one(struct pcpu_vstats *result, struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	int cpu;
  
  	result->packets = 0;
  	result->bytes = 0;
  	for_each_possible_cpu(cpu) {
  		struct pcpu_vstats *stats = per_cpu_ptr(dev->vstats, cpu);
  		u64 packets, bytes;
  		unsigned int start;
  
  		do {
  			start = u64_stats_fetch_begin_bh(&stats->syncp);
  			packets = stats->packets;
  			bytes = stats->bytes;
  		} while (u64_stats_fetch_retry_bh(&stats->syncp, start));
  		result->packets += packets;
  		result->bytes += bytes;
  	}
  	return atomic64_read(&priv->dropped);
  }
  
  static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,
  						  struct rtnl_link_stats64 *tot)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer;
  	struct pcpu_vstats one;
  
  	tot->tx_dropped = veth_stats_one(&one, dev);
  	tot->tx_bytes = one.bytes;
  	tot->tx_packets = one.packets;
  
  	rcu_read_lock();
  	peer = rcu_dereference(priv->peer);
  	if (peer) {
  		tot->rx_dropped = veth_stats_one(&one, peer);
  		tot->rx_bytes = one.bytes;
  		tot->rx_packets = one.packets;
  	}
  	rcu_read_unlock();
  
  	return tot;
  }
  
  /* fake multicast ability */
  static void veth_set_multicast_list(struct net_device *dev)
  {
  }
  
  static int veth_open(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer = rtnl_dereference(priv->peer);
  
  	if (!peer)
  		return -ENOTCONN;
  
  	if (peer->flags & IFF_UP) {
  		netif_carrier_on(dev);
  		netif_carrier_on(peer);
  	}
  	return 0;
  }
  
  static int veth_close(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer = rtnl_dereference(priv->peer);
  
  	netif_carrier_off(dev);
  	if (peer)
  		netif_carrier_off(peer);
  
  	return 0;
  }
  
  static int is_valid_veth_mtu(int new_mtu)
  {
  	return new_mtu >= MIN_MTU && new_mtu <= MAX_MTU;
  }
  
  static int veth_change_mtu(struct net_device *dev, int new_mtu)
  {
  	if (!is_valid_veth_mtu(new_mtu))
  		return -EINVAL;
  	dev->mtu = new_mtu;
  	return 0;
  }
  
  static int veth_dev_init(struct net_device *dev)
  {
  	int i;
  
  	dev->vstats = alloc_percpu(struct pcpu_vstats);
  	if (!dev->vstats)
  		return -ENOMEM;
  
  	for_each_possible_cpu(i) {
  		struct pcpu_vstats *veth_stats;
  		veth_stats = per_cpu_ptr(dev->vstats, i);
  		u64_stats_init(&veth_stats->syncp);
  	}
  
  	return 0;
  }
  
  static void veth_dev_free(struct net_device *dev)
  {
  	free_percpu(dev->vstats);
  	free_netdev(dev);
  }
  
  static const struct net_device_ops veth_netdev_ops = {
  	.ndo_init            = veth_dev_init,
  	.ndo_open            = veth_open,
  	.ndo_stop            = veth_close,
  	.ndo_start_xmit      = veth_xmit,
  	.ndo_change_mtu      = veth_change_mtu,
  	.ndo_get_stats64     = veth_get_stats64,
  	.ndo_set_rx_mode     = veth_set_multicast_list,
  	.ndo_set_mac_address = eth_mac_addr,
  };
  
  #define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_ALL_TSO |    \
  		       NETIF_F_HW_CSUM | NETIF_F_RXCSUM | NETIF_F_HIGHDMA | \
  		       NETIF_F_GSO_GRE | NETIF_F_GSO_UDP_TUNNEL |	    \
  		       NETIF_F_GSO_IPIP | NETIF_F_GSO_SIT | NETIF_F_UFO	|   \
  		       NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_CTAG_RX | \
  		       NETIF_F_HW_VLAN_STAG_TX | NETIF_F_HW_VLAN_STAG_RX )
  
  static void veth_setup(struct net_device *dev)
  {
  	ether_setup(dev);
  
  	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
  	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
  
  	dev->netdev_ops = &veth_netdev_ops;
  	dev->ethtool_ops = &veth_ethtool_ops;
  	dev->features |= NETIF_F_LLTX;
  	dev->features |= VETH_FEATURES;
  	dev->vlan_features = dev->features &
  			     ~(NETIF_F_HW_VLAN_CTAG_TX |
  			       NETIF_F_HW_VLAN_STAG_TX |
  			       NETIF_F_HW_VLAN_CTAG_RX |
  			       NETIF_F_HW_VLAN_STAG_RX);
  	dev->destructor = veth_dev_free;
  
  	dev->hw_features = VETH_FEATURES;
  	dev->hw_enc_features = VETH_FEATURES;
  }
  
  /*
   * netlink interface
   */
  
  static int veth_validate(struct nlattr *tb[], struct nlattr *data[])
  {
  	if (tb[IFLA_ADDRESS]) {
  		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
  			return -EINVAL;
  		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
  			return -EADDRNOTAVAIL;
  	}
  	if (tb[IFLA_MTU]) {
  		if (!is_valid_veth_mtu(nla_get_u32(tb[IFLA_MTU])))
  			return -EINVAL;
  	}
  	return 0;
  }
  
  static struct rtnl_link_ops veth_link_ops;
  
  static int veth_newlink(struct net *src_net, struct net_device *dev,
  			 struct nlattr *tb[], struct nlattr *data[])
  {
  	int err;
  	struct net_device *peer;
  	struct veth_priv *priv;
  	char ifname[IFNAMSIZ];
  	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;
  	struct ifinfomsg *ifmp;
  	struct net *net;
  
  	/*
  	 * create and register peer first
  	 */
  	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
  		struct nlattr *nla_peer;
  
  		nla_peer = data[VETH_INFO_PEER];
  		ifmp = nla_data(nla_peer);
  		err = nla_parse(peer_tb, IFLA_MAX,
  				nla_data(nla_peer) + sizeof(struct ifinfomsg),
  				nla_len(nla_peer) - sizeof(struct ifinfomsg),
  				ifla_policy);
  		if (err < 0)
  			return err;
  
  		err = veth_validate(peer_tb, NULL);
  		if (err < 0)
  			return err;
  
  		tbp = peer_tb;
  	} else {
  		ifmp = NULL;
  		tbp = tb;
  	}
  
  	if (tbp[IFLA_IFNAME])
  		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
  	else
  		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
  
  	net = rtnl_link_get_net(src_net, tbp);
  	if (IS_ERR(net))
  		return PTR_ERR(net);
  
  	peer = rtnl_create_link(net, ifname, &veth_link_ops, tbp);
  	if (IS_ERR(peer)) {
  		put_net(net);
  		return PTR_ERR(peer);
  	}
  
  	if (tbp[IFLA_ADDRESS] == NULL)
  		eth_hw_addr_random(peer);
  
  	if (ifmp && (dev->ifindex != 0))
  		peer->ifindex = ifmp->ifi_index;
  
  	err = register_netdevice(peer);
  	put_net(net);
  	net = NULL;
  	if (err < 0)
  		goto err_register_peer;
  
  	netif_carrier_off(peer);
  
  	err = rtnl_configure_link(peer, ifmp);
  	if (err < 0)
  		goto err_configure_peer;
  
  	/*
  	 * register dev last
  	 *
  	 * note, that since we've registered new device the dev's name
  	 * should be re-allocated
  	 */
  
  	if (tb[IFLA_ADDRESS] == NULL)
  		eth_hw_addr_random(dev);
  
  	if (tb[IFLA_IFNAME])
  		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
  	else
  		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
  
  	err = register_netdevice(dev);
  	if (err < 0)
  		goto err_register_dev;
  
  	netif_carrier_off(dev);
  
  	/*
  	 * tie the deviced together
  	 */
  
  	priv = netdev_priv(dev);
  	rcu_assign_pointer(priv->peer, peer);
  
  	priv = netdev_priv(peer);
  	rcu_assign_pointer(priv->peer, dev);
  	return 0;
  
  err_register_dev:
  	/* nothing to do */
  err_configure_peer:
  	unregister_netdevice(peer);
  	return err;
  
  err_register_peer:
  	free_netdev(peer);
  	return err;
  }
  
  static void veth_dellink(struct net_device *dev, struct list_head *head)
  {
  	struct veth_priv *priv;
  	struct net_device *peer;
  
  	priv = netdev_priv(dev);
  	peer = rtnl_dereference(priv->peer);
  
  	/* Note : dellink() is called from default_device_exit_batch(),
  	 * before a rcu_synchronize() point. The devices are guaranteed
  	 * not being freed before one RCU grace period.
  	 */
  	RCU_INIT_POINTER(priv->peer, NULL);
  	unregister_netdevice_queue(dev, head);
  
  	if (peer) {
  		priv = netdev_priv(peer);
  		RCU_INIT_POINTER(priv->peer, NULL);
  		unregister_netdevice_queue(peer, head);
  	}
  }
  
  static const struct nla_policy veth_policy[VETH_INFO_MAX + 1] = {
  	[VETH_INFO_PEER]	= { .len = sizeof(struct ifinfomsg) },
  };
  
  static struct rtnl_link_ops veth_link_ops = {
  	.kind		= DRV_NAME,
  	.priv_size	= sizeof(struct veth_priv),
  	.setup		= veth_setup,
  	.validate	= veth_validate,
  	.newlink	= veth_newlink,
  	.dellink	= veth_dellink,
  	.policy		= veth_policy,
  	.maxtype	= VETH_INFO_MAX,
  };
  
  /*
   * init/fini
   */
  
  static __init int veth_init(void)
  {
  	return rtnl_link_register(&veth_link_ops);
  }
  
  static __exit void veth_exit(void)
  {
  	rtnl_link_unregister(&veth_link_ops);
  }
  
  module_init(veth_init);
  module_exit(veth_exit);
  
  MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS_RTNL_LINK(DRV_NAME);