// SPDX-License-Identifier: GPL-2.0-only

  /*
   *  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/rtnetlink.h>

  #include <net/dst.h>
  #include <net/xfrm.h>

  #include <net/xdp.h>

  #include <linux/veth.h>

  #include <linux/module.h>

  #include <linux/bpf.h>
  #include <linux/filter.h>
  #include <linux/ptr_ring.h>

  #include <linux/bpf_trace.h>

  #include <linux/net_tstamp.h>

  
  #define DRV_NAME	"veth"
  #define DRV_VERSION	"1.0"

  #define VETH_XDP_FLAG		BIT(0)

  #define VETH_RING_SIZE		256
  #define VETH_XDP_HEADROOM	(XDP_PACKET_HEADROOM + NET_IP_ALIGN)

  #define VETH_XDP_TX_BULK_SIZE	16

  struct veth_stats {

  	u64	rx_drops;
  	/* xdp */

  	u64	xdp_packets;
  	u64	xdp_bytes;

  	u64	xdp_redirect;

  	u64	xdp_drops;

  	u64	xdp_tx;

  	u64	xdp_tx_err;

  	u64	peer_tq_xdp_xmit;
  	u64	peer_tq_xdp_xmit_err;

  };

  struct veth_rq_stats {

  	struct veth_stats	vs;

  	struct u64_stats_sync	syncp;
  };

  struct veth_rq {

  	struct napi_struct	xdp_napi;
  	struct net_device	*dev;
  	struct bpf_prog __rcu	*xdp_prog;

  	struct xdp_mem_info	xdp_mem;

  	struct veth_rq_stats	stats;

  	bool			rx_notify_masked;
  	struct ptr_ring		xdp_ring;
  	struct xdp_rxq_info	xdp_rxq;

  };

  struct veth_priv {
  	struct net_device __rcu	*peer;
  	atomic64_t		dropped;
  	struct bpf_prog		*_xdp_prog;
  	struct veth_rq		*rq;
  	unsigned int		requested_headroom;
  };

  struct veth_xdp_tx_bq {
  	struct xdp_frame *q[VETH_XDP_TX_BULK_SIZE];
  	unsigned int count;
  };

  /*
   * ethtool interface
   */

  struct veth_q_stat_desc {
  	char	desc[ETH_GSTRING_LEN];
  	size_t	offset;
  };

  #define VETH_RQ_STAT(m)	offsetof(struct veth_stats, m)

  
  static const struct veth_q_stat_desc veth_rq_stats_desc[] = {
  	{ "xdp_packets",	VETH_RQ_STAT(xdp_packets) },
  	{ "xdp_bytes",		VETH_RQ_STAT(xdp_bytes) },

  	{ "drops",		VETH_RQ_STAT(rx_drops) },
  	{ "xdp_redirect",	VETH_RQ_STAT(xdp_redirect) },
  	{ "xdp_drops",		VETH_RQ_STAT(xdp_drops) },
  	{ "xdp_tx",		VETH_RQ_STAT(xdp_tx) },
  	{ "xdp_tx_errors",	VETH_RQ_STAT(xdp_tx_err) },

  };
  
  #define VETH_RQ_STATS_LEN	ARRAY_SIZE(veth_rq_stats_desc)

  static const struct veth_q_stat_desc veth_tq_stats_desc[] = {
  	{ "xdp_xmit",		VETH_RQ_STAT(peer_tq_xdp_xmit) },
  	{ "xdp_xmit_errors",	VETH_RQ_STAT(peer_tq_xdp_xmit_err) },
  };
  
  #define VETH_TQ_STATS_LEN	ARRAY_SIZE(veth_tq_stats_desc)

  static struct {
  	const char string[ETH_GSTRING_LEN];
  } ethtool_stats_keys[] = {
  	{ "peer_ifindex" },
  };

  static int veth_get_link_ksettings(struct net_device *dev,
  				   struct ethtool_link_ksettings *cmd)

  {

  	cmd->base.speed		= SPEED_10000;
  	cmd->base.duplex	= DUPLEX_FULL;
  	cmd->base.port		= PORT_TP;
  	cmd->base.autoneg	= AUTONEG_DISABLE;

  	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)
  {

  	char *p = (char *)buf;
  	int i, j;

  	switch(stringset) {
  	case ETH_SS_STATS:

  		memcpy(p, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
  		p += sizeof(ethtool_stats_keys);
  		for (i = 0; i < dev->real_num_rx_queues; i++) {
  			for (j = 0; j < VETH_RQ_STATS_LEN; j++) {

  				snprintf(p, ETH_GSTRING_LEN,

  					 "rx_queue_%u_%.18s",

  					 i, veth_rq_stats_desc[j].desc);
  				p += ETH_GSTRING_LEN;
  			}
  		}

  		for (i = 0; i < dev->real_num_tx_queues; i++) {
  			for (j = 0; j < VETH_TQ_STATS_LEN; j++) {
  				snprintf(p, ETH_GSTRING_LEN,
  					 "tx_queue_%u_%.18s",
  					 i, veth_tq_stats_desc[j].desc);
  				p += ETH_GSTRING_LEN;
  			}
  		}

  		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) +

  		       VETH_RQ_STATS_LEN * dev->real_num_rx_queues +
  		       VETH_TQ_STATS_LEN * dev->real_num_tx_queues;

  	default:
  		return -EOPNOTSUPP;
  	}

  }
  
  static void veth_get_ethtool_stats(struct net_device *dev,
  		struct ethtool_stats *stats, u64 *data)
  {

  	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);

  	struct net_device *peer = rtnl_dereference(priv->peer);

  	int i, j, idx;

  	data[0] = peer ? peer->ifindex : 0;

  	idx = 1;
  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		const struct veth_rq_stats *rq_stats = &priv->rq[i].stats;

  		const void *stats_base = (void *)&rq_stats->vs;

  		unsigned int start;
  		size_t offset;
  
  		do {
  			start = u64_stats_fetch_begin_irq(&rq_stats->syncp);
  			for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
  				offset = veth_rq_stats_desc[j].offset;
  				data[idx + j] = *(u64 *)(stats_base + offset);
  			}
  		} while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
  		idx += VETH_RQ_STATS_LEN;
  	}

  
  	if (!peer)
  		return;
  
  	rcv_priv = netdev_priv(peer);
  	for (i = 0; i < peer->real_num_rx_queues; i++) {
  		const struct veth_rq_stats *rq_stats = &rcv_priv->rq[i].stats;
  		const void *base = (void *)&rq_stats->vs;
  		unsigned int start, tx_idx = idx;
  		size_t offset;
  
  		tx_idx += (i % dev->real_num_tx_queues) * VETH_TQ_STATS_LEN;
  		do {
  			start = u64_stats_fetch_begin_irq(&rq_stats->syncp);
  			for (j = 0; j < VETH_TQ_STATS_LEN; j++) {
  				offset = veth_tq_stats_desc[j].offset;
  				data[tx_idx + j] += *(u64 *)(base + offset);
  			}
  		} while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
  	}

  }

  static const struct ethtool_ops veth_ethtool_ops = {

  	.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,

  	.get_link_ksettings	= veth_get_link_ksettings,

  	.get_ts_info		= ethtool_op_get_ts_info,

  };

  /* general routines */

  static bool veth_is_xdp_frame(void *ptr)
  {
  	return (unsigned long)ptr & VETH_XDP_FLAG;
  }

  static struct xdp_frame *veth_ptr_to_xdp(void *ptr)

  {
  	return (void *)((unsigned long)ptr & ~VETH_XDP_FLAG);
  }

  static void *veth_xdp_to_ptr(struct xdp_frame *xdp)

  {

  	return (void *)((unsigned long)xdp | VETH_XDP_FLAG);

  }

  static void veth_ptr_free(void *ptr)
  {
  	if (veth_is_xdp_frame(ptr))
  		xdp_return_frame(veth_ptr_to_xdp(ptr));
  	else
  		kfree_skb(ptr);
  }

  static void __veth_xdp_flush(struct veth_rq *rq)

  {
  	/* Write ptr_ring before reading rx_notify_masked */
  	smp_mb();

  	if (!rq->rx_notify_masked) {
  		rq->rx_notify_masked = true;
  		napi_schedule(&rq->xdp_napi);

  	}
  }

  static int veth_xdp_rx(struct veth_rq *rq, struct sk_buff *skb)

  {

  	if (unlikely(ptr_ring_produce(&rq->xdp_ring, skb))) {

  		dev_kfree_skb_any(skb);
  		return NET_RX_DROP;
  	}
  
  	return NET_RX_SUCCESS;
  }

  static int veth_forward_skb(struct net_device *dev, struct sk_buff *skb,
  			    struct veth_rq *rq, bool xdp)

  {

  	return __dev_forward_skb(dev, skb) ?: xdp ?

  		veth_xdp_rx(rq, skb) :

  		netif_rx(skb);
  }
  
  static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);

  	struct veth_rq *rq = NULL;

  	struct net_device *rcv;

  	int length = skb->len;

  	bool rcv_xdp = false;

  	int rxq;

  	rcu_read_lock();
  	rcv = rcu_dereference(priv->peer);
  	if (unlikely(!rcv)) {
  		kfree_skb(skb);
  		goto drop;
  	}

  	rcv_priv = netdev_priv(rcv);

  	rxq = skb_get_queue_mapping(skb);
  	if (rxq < rcv->real_num_rx_queues) {
  		rq = &rcv_priv->rq[rxq];
  		rcv_xdp = rcu_access_pointer(rq->xdp_prog);
  		if (rcv_xdp)
  			skb_record_rx_queue(skb, rxq);
  	}

  	skb_tx_timestamp(skb);

  	if (likely(veth_forward_skb(rcv, skb, rq, rcv_xdp) == NET_RX_SUCCESS)) {

  		if (!rcv_xdp)
  			dev_lstats_add(dev, length);

  	} else {

  drop:

  		atomic64_inc(&priv->dropped);
  	}

  
  	if (rcv_xdp)

  		__veth_xdp_flush(rq);

  	rcu_read_unlock();

  	return NETDEV_TX_OK;

  }

  static u64 veth_stats_tx(struct net_device *dev, u64 *packets, u64 *bytes)

  {

  	struct veth_priv *priv = netdev_priv(dev);

  	dev_lstats_read(dev, packets, bytes);

  	return atomic64_read(&priv->dropped);
  }

  static void veth_stats_rx(struct veth_stats *result, struct net_device *dev)

  {
  	struct veth_priv *priv = netdev_priv(dev);
  	int i;

  	result->peer_tq_xdp_xmit_err = 0;

  	result->xdp_packets = 0;

  	result->xdp_tx_err = 0;

  	result->xdp_bytes = 0;

  	result->rx_drops = 0;

  	for (i = 0; i < dev->num_rx_queues; i++) {

  		u64 packets, bytes, drops, xdp_tx_err, peer_tq_xdp_xmit_err;

  		struct veth_rq_stats *stats = &priv->rq[i].stats;

  		unsigned int start;
  
  		do {
  			start = u64_stats_fetch_begin_irq(&stats->syncp);

  			peer_tq_xdp_xmit_err = stats->vs.peer_tq_xdp_xmit_err;

  			xdp_tx_err = stats->vs.xdp_tx_err;

  			packets = stats->vs.xdp_packets;
  			bytes = stats->vs.xdp_bytes;

  			drops = stats->vs.rx_drops;

  		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));

  		result->peer_tq_xdp_xmit_err += peer_tq_xdp_xmit_err;

  		result->xdp_tx_err += xdp_tx_err;

  		result->xdp_packets += packets;
  		result->xdp_bytes += bytes;

  		result->rx_drops += drops;

  	}
  }

  static void veth_get_stats64(struct net_device *dev,
  			     struct rtnl_link_stats64 *tot)

  {
  	struct veth_priv *priv = netdev_priv(dev);

  	struct net_device *peer;

  	struct veth_stats rx;

  	u64 packets, bytes;

  	tot->tx_dropped = veth_stats_tx(dev, &packets, &bytes);
  	tot->tx_bytes = bytes;
  	tot->tx_packets = packets;

  	veth_stats_rx(&rx, dev);

  	tot->tx_dropped += rx.xdp_tx_err;
  	tot->rx_dropped = rx.rx_drops + rx.peer_tq_xdp_xmit_err;

  	tot->rx_bytes = rx.xdp_bytes;
  	tot->rx_packets = rx.xdp_packets;

  	rcu_read_lock();
  	peer = rcu_dereference(priv->peer);
  	if (peer) {

  		veth_stats_tx(peer, &packets, &bytes);

  		tot->rx_bytes += bytes;
  		tot->rx_packets += packets;

  
  		veth_stats_rx(&rx, peer);

  		tot->tx_dropped += rx.peer_tq_xdp_xmit_err;
  		tot->rx_dropped += rx.xdp_tx_err;

  		tot->tx_bytes += rx.xdp_bytes;
  		tot->tx_packets += rx.xdp_packets;

  	}
  	rcu_read_unlock();

  }

  /* fake multicast ability */
  static void veth_set_multicast_list(struct net_device *dev)
  {
  }

  static struct sk_buff *veth_build_skb(void *head, int headroom, int len,
  				      int buflen)
  {
  	struct sk_buff *skb;

  	skb = build_skb(head, buflen);
  	if (!skb)
  		return NULL;
  
  	skb_reserve(skb, headroom);
  	skb_put(skb, len);
  
  	return skb;
  }

  static int veth_select_rxq(struct net_device *dev)
  {
  	return smp_processor_id() % dev->real_num_rx_queues;
  }

  static struct net_device *veth_peer_dev(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  
  	/* Callers must be under RCU read side. */
  	return rcu_dereference(priv->peer);
  }

  static int veth_xdp_xmit(struct net_device *dev, int n,

  			 struct xdp_frame **frames,
  			 u32 flags, bool ndo_xmit)

  {
  	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);

  	int i, ret = -ENXIO, drops = 0;

  	struct net_device *rcv;

  	unsigned int max_len;

  	struct veth_rq *rq;

  	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))

  		return -EINVAL;

  	rcu_read_lock();

  	rcv = rcu_dereference(priv->peer);

  	if (unlikely(!rcv))
  		goto out;

  
  	rcv_priv = netdev_priv(rcv);

  	rq = &rcv_priv->rq[veth_select_rxq(rcv)];

  	/* Non-NULL xdp_prog ensures that xdp_ring is initialized on receive
  	 * side. This means an XDP program is loaded on the peer and the peer
  	 * device is up.
  	 */

  	if (!rcu_access_pointer(rq->xdp_prog))
  		goto out;

  
  	max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;

  	spin_lock(&rq->xdp_ring.producer_lock);

  	for (i = 0; i < n; i++) {
  		struct xdp_frame *frame = frames[i];
  		void *ptr = veth_xdp_to_ptr(frame);
  
  		if (unlikely(frame->len > max_len ||

  			     __ptr_ring_produce(&rq->xdp_ring, ptr))) {

  			xdp_return_frame_rx_napi(frame);
  			drops++;
  		}
  	}

  	spin_unlock(&rq->xdp_ring.producer_lock);

  
  	if (flags & XDP_XMIT_FLUSH)

  		__veth_xdp_flush(rq);

  	ret = n - drops;

  	if (ndo_xmit) {

  		u64_stats_update_begin(&rq->stats.syncp);
  		rq->stats.vs.peer_tq_xdp_xmit += n - drops;
  		rq->stats.vs.peer_tq_xdp_xmit_err += drops;
  		u64_stats_update_end(&rq->stats.syncp);

  	}

  out:

  	rcu_read_unlock();

  
  	return ret;

  }

  static int veth_ndo_xdp_xmit(struct net_device *dev, int n,
  			     struct xdp_frame **frames, u32 flags)
  {

  	int err;
  
  	err = veth_xdp_xmit(dev, n, frames, flags, true);
  	if (err < 0) {
  		struct veth_priv *priv = netdev_priv(dev);
  
  		atomic64_add(n, &priv->dropped);
  	}
  
  	return err;

  }

  static void veth_xdp_flush_bq(struct veth_rq *rq, struct veth_xdp_tx_bq *bq)

  {
  	int sent, i, err = 0;

  	sent = veth_xdp_xmit(rq->dev, bq->count, bq->q, 0, false);

  	if (sent < 0) {
  		err = sent;
  		sent = 0;
  		for (i = 0; i < bq->count; i++)
  			xdp_return_frame(bq->q[i]);
  	}

  	trace_xdp_bulk_tx(rq->dev, sent, bq->count - sent, err);

  	u64_stats_update_begin(&rq->stats.syncp);
  	rq->stats.vs.xdp_tx += sent;
  	rq->stats.vs.xdp_tx_err += bq->count - sent;
  	u64_stats_update_end(&rq->stats.syncp);

  	bq->count = 0;
  }

  static void veth_xdp_flush(struct veth_rq *rq, struct veth_xdp_tx_bq *bq)

  {

  	struct veth_priv *rcv_priv, *priv = netdev_priv(rq->dev);

  	struct net_device *rcv;

  	struct veth_rq *rcv_rq;

  
  	rcu_read_lock();

  	veth_xdp_flush_bq(rq, bq);

  	rcv = rcu_dereference(priv->peer);
  	if (unlikely(!rcv))
  		goto out;
  
  	rcv_priv = netdev_priv(rcv);

  	rcv_rq = &rcv_priv->rq[veth_select_rxq(rcv)];

  	/* xdp_ring is initialized on receive side? */

  	if (unlikely(!rcu_access_pointer(rcv_rq->xdp_prog)))

  		goto out;

  	__veth_xdp_flush(rcv_rq);

  out:
  	rcu_read_unlock();
  }

  static int veth_xdp_tx(struct veth_rq *rq, struct xdp_buff *xdp,

  		       struct veth_xdp_tx_bq *bq)

  {

  	struct xdp_frame *frame = xdp_convert_buff_to_frame(xdp);

  
  	if (unlikely(!frame))
  		return -EOVERFLOW;

  	if (unlikely(bq->count == VETH_XDP_TX_BULK_SIZE))

  		veth_xdp_flush_bq(rq, bq);

  
  	bq->q[bq->count++] = frame;
  
  	return 0;

  }

  static struct sk_buff *veth_xdp_rcv_one(struct veth_rq *rq,

  					struct xdp_frame *frame,

  					struct veth_xdp_tx_bq *bq,
  					struct veth_stats *stats)

  {
  	void *hard_start = frame->data - frame->headroom;

  	int len = frame->len, delta = 0;

  	struct xdp_frame orig_frame;

  	struct bpf_prog *xdp_prog;
  	unsigned int headroom;
  	struct sk_buff *skb;

  	/* bpf_xdp_adjust_head() assures BPF cannot access xdp_frame area */
  	hard_start -= sizeof(struct xdp_frame);

  	rcu_read_lock();

  	xdp_prog = rcu_dereference(rq->xdp_prog);

  	if (likely(xdp_prog)) {
  		struct xdp_buff xdp;
  		u32 act;

  		xdp_convert_frame_to_buff(frame, &xdp);

  		xdp.rxq = &rq->xdp_rxq;

  
  		act = bpf_prog_run_xdp(xdp_prog, &xdp);
  
  		switch (act) {
  		case XDP_PASS:
  			delta = frame->data - xdp.data;
  			len = xdp.data_end - xdp.data;
  			break;

  		case XDP_TX:
  			orig_frame = *frame;

  			xdp.rxq->mem = frame->mem;

  			if (unlikely(veth_xdp_tx(rq, &xdp, bq) < 0)) {

  				trace_xdp_exception(rq->dev, xdp_prog, act);

  				frame = &orig_frame;

  				stats->rx_drops++;

  				goto err_xdp;
  			}

  			stats->xdp_tx++;

  			rcu_read_unlock();
  			goto xdp_xmit;
  		case XDP_REDIRECT:
  			orig_frame = *frame;

  			xdp.rxq->mem = frame->mem;

  			if (xdp_do_redirect(rq->dev, &xdp, xdp_prog)) {

  				frame = &orig_frame;

  				stats->rx_drops++;

  				goto err_xdp;
  			}

  			stats->xdp_redirect++;

  			rcu_read_unlock();
  			goto xdp_xmit;

  		default:
  			bpf_warn_invalid_xdp_action(act);

  			fallthrough;

  		case XDP_ABORTED:

  			trace_xdp_exception(rq->dev, xdp_prog, act);

  			fallthrough;

  		case XDP_DROP:

  			stats->xdp_drops++;

  			goto err_xdp;
  		}
  	}
  	rcu_read_unlock();
  
  	headroom = sizeof(struct xdp_frame) + frame->headroom - delta;

  	skb = veth_build_skb(hard_start, headroom, len, frame->frame_sz);

  	if (!skb) {
  		xdp_return_frame(frame);

  		stats->rx_drops++;

  		goto err;
  	}

  	xdp_release_frame(frame);

  	xdp_scrub_frame(frame);

  	skb->protocol = eth_type_trans(skb, rq->dev);

  err:
  	return skb;
  err_xdp:
  	rcu_read_unlock();
  	xdp_return_frame(frame);

  xdp_xmit:

  	return NULL;
  }

  static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq,
  					struct sk_buff *skb,
  					struct veth_xdp_tx_bq *bq,
  					struct veth_stats *stats)

  {
  	u32 pktlen, headroom, act, metalen;
  	void *orig_data, *orig_data_end;
  	struct bpf_prog *xdp_prog;
  	int mac_len, delta, off;
  	struct xdp_buff xdp;

  	skb_orphan(skb);

  	rcu_read_lock();

  	xdp_prog = rcu_dereference(rq->xdp_prog);

  	if (unlikely(!xdp_prog)) {
  		rcu_read_unlock();
  		goto out;
  	}
  
  	mac_len = skb->data - skb_mac_header(skb);
  	pktlen = skb->len + mac_len;
  	headroom = skb_headroom(skb) - mac_len;
  
  	if (skb_shared(skb) || skb_head_is_locked(skb) ||
  	    skb_is_nonlinear(skb) || headroom < XDP_PACKET_HEADROOM) {
  		struct sk_buff *nskb;
  		int size, head_off;
  		void *head, *start;
  		struct page *page;
  
  		size = SKB_DATA_ALIGN(VETH_XDP_HEADROOM + pktlen) +
  		       SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
  		if (size > PAGE_SIZE)
  			goto drop;
  
  		page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
  		if (!page)
  			goto drop;
  
  		head = page_address(page);
  		start = head + VETH_XDP_HEADROOM;
  		if (skb_copy_bits(skb, -mac_len, start, pktlen)) {
  			page_frag_free(head);
  			goto drop;
  		}

  		nskb = veth_build_skb(head, VETH_XDP_HEADROOM + mac_len,
  				      skb->len, PAGE_SIZE);

  		if (!nskb) {
  			page_frag_free(head);
  			goto drop;
  		}
  
  		skb_copy_header(nskb, skb);
  		head_off = skb_headroom(nskb) - skb_headroom(skb);
  		skb_headers_offset_update(nskb, head_off);

  		consume_skb(skb);
  		skb = nskb;
  	}
  
  	xdp.data_hard_start = skb->head;
  	xdp.data = skb_mac_header(skb);
  	xdp.data_end = xdp.data + pktlen;
  	xdp.data_meta = xdp.data;

  	xdp.rxq = &rq->xdp_rxq;

  
  	/* SKB "head" area always have tailroom for skb_shared_info */
  	xdp.frame_sz = (void *)skb_end_pointer(skb) - xdp.data_hard_start;
  	xdp.frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

  	orig_data = xdp.data;
  	orig_data_end = xdp.data_end;
  
  	act = bpf_prog_run_xdp(xdp_prog, &xdp);
  
  	switch (act) {
  	case XDP_PASS:
  		break;

  	case XDP_TX:
  		get_page(virt_to_page(xdp.data));
  		consume_skb(skb);

  		xdp.rxq->mem = rq->xdp_mem;

  		if (unlikely(veth_xdp_tx(rq, &xdp, bq) < 0)) {

  			trace_xdp_exception(rq->dev, xdp_prog, act);

  			stats->rx_drops++;

  			goto err_xdp;
  		}

  		stats->xdp_tx++;

  		rcu_read_unlock();
  		goto xdp_xmit;
  	case XDP_REDIRECT:
  		get_page(virt_to_page(xdp.data));
  		consume_skb(skb);

  		xdp.rxq->mem = rq->xdp_mem;

  		if (xdp_do_redirect(rq->dev, &xdp, xdp_prog)) {
  			stats->rx_drops++;

  			goto err_xdp;

  		}
  		stats->xdp_redirect++;

  		rcu_read_unlock();
  		goto xdp_xmit;

  	default:
  		bpf_warn_invalid_xdp_action(act);

  		fallthrough;

  	case XDP_ABORTED:

  		trace_xdp_exception(rq->dev, xdp_prog, act);

  		fallthrough;

  	case XDP_DROP:

  		stats->xdp_drops++;
  		goto xdp_drop;

  	}
  	rcu_read_unlock();

  	/* check if bpf_xdp_adjust_head was used */

  	delta = orig_data - xdp.data;
  	off = mac_len + delta;
  	if (off > 0)
  		__skb_push(skb, off);
  	else if (off < 0)
  		__skb_pull(skb, -off);
  	skb->mac_header -= delta;

  
  	/* check if bpf_xdp_adjust_tail was used */

  	off = xdp.data_end - orig_data_end;
  	if (off != 0)

  		__skb_put(skb, off); /* positive on grow, negative on shrink */

  	skb->protocol = eth_type_trans(skb, rq->dev);

  
  	metalen = xdp.data - xdp.data_meta;
  	if (metalen)
  		skb_metadata_set(skb, metalen);
  out:
  	return skb;
  drop:

  	stats->rx_drops++;
  xdp_drop:

  	rcu_read_unlock();
  	kfree_skb(skb);
  	return NULL;

  err_xdp:
  	rcu_read_unlock();
  	page_frag_free(xdp.data);
  xdp_xmit:
  	return NULL;

  }

  static int veth_xdp_rcv(struct veth_rq *rq, int budget,
  			struct veth_xdp_tx_bq *bq,
  			struct veth_stats *stats)

  {

  	int i, done = 0;

  
  	for (i = 0; i < budget; i++) {

  		void *ptr = __ptr_ring_consume(&rq->xdp_ring);

  		struct sk_buff *skb;

  		if (!ptr)

  			break;

  		if (veth_is_xdp_frame(ptr)) {

  			struct xdp_frame *frame = veth_ptr_to_xdp(ptr);

  			stats->xdp_bytes += frame->len;
  			skb = veth_xdp_rcv_one(rq, frame, bq, stats);

  		} else {

  			skb = ptr;

  			stats->xdp_bytes += skb->len;
  			skb = veth_xdp_rcv_skb(rq, skb, bq, stats);

  		}

  
  		if (skb)

  			napi_gro_receive(&rq->xdp_napi, skb);

  
  		done++;
  	}

  	u64_stats_update_begin(&rq->stats.syncp);

  	rq->stats.vs.xdp_redirect += stats->xdp_redirect;

  	rq->stats.vs.xdp_bytes += stats->xdp_bytes;

  	rq->stats.vs.xdp_drops += stats->xdp_drops;
  	rq->stats.vs.rx_drops += stats->rx_drops;

  	rq->stats.vs.xdp_packets += done;

  	u64_stats_update_end(&rq->stats.syncp);

  	return done;
  }
  
  static int veth_poll(struct napi_struct *napi, int budget)
  {

  	struct veth_rq *rq =
  		container_of(napi, struct veth_rq, xdp_napi);

  	struct veth_stats stats = {};

  	struct veth_xdp_tx_bq bq;

  	int done;

  	bq.count = 0;

  	xdp_set_return_frame_no_direct();

  	done = veth_xdp_rcv(rq, budget, &bq, &stats);

  
  	if (done < budget && napi_complete_done(napi, done)) {
  		/* Write rx_notify_masked before reading ptr_ring */

  		smp_store_mb(rq->rx_notify_masked, false);
  		if (unlikely(!__ptr_ring_empty(&rq->xdp_ring))) {
  			rq->rx_notify_masked = true;
  			napi_schedule(&rq->xdp_napi);

  		}
  	}

  	if (stats.xdp_tx > 0)

  		veth_xdp_flush(rq, &bq);

  	if (stats.xdp_redirect > 0)

  		xdp_do_flush();

  	xdp_clear_return_frame_no_direct();

  	return done;
  }
  
  static int veth_napi_add(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);

  	int err, i;

  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		struct veth_rq *rq = &priv->rq[i];
  
  		err = ptr_ring_init(&rq->xdp_ring, VETH_RING_SIZE, GFP_KERNEL);
  		if (err)
  			goto err_xdp_ring;
  	}

  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		struct veth_rq *rq = &priv->rq[i];
  
  		netif_napi_add(dev, &rq->xdp_napi, veth_poll, NAPI_POLL_WEIGHT);
  		napi_enable(&rq->xdp_napi);
  	}

  
  	return 0;

  err_xdp_ring:
  	for (i--; i >= 0; i--)
  		ptr_ring_cleanup(&priv->rq[i].xdp_ring, veth_ptr_free);
  
  	return err;

  }
  
  static void veth_napi_del(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);

  	int i;

  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		struct veth_rq *rq = &priv->rq[i];
  
  		napi_disable(&rq->xdp_napi);

  		__netif_napi_del(&rq->xdp_napi);

  	}
  	synchronize_net();
  
  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		struct veth_rq *rq = &priv->rq[i];

  		rq->rx_notify_masked = false;
  		ptr_ring_cleanup(&rq->xdp_ring, veth_ptr_free);
  	}

  }
  
  static int veth_enable_xdp(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);

  	int err, i;

  	if (!xdp_rxq_info_is_reg(&priv->rq[0].xdp_rxq)) {
  		for (i = 0; i < dev->real_num_rx_queues; i++) {
  			struct veth_rq *rq = &priv->rq[i];

  			err = xdp_rxq_info_reg(&rq->xdp_rxq, dev, i);
  			if (err < 0)
  				goto err_rxq_reg;
  
  			err = xdp_rxq_info_reg_mem_model(&rq->xdp_rxq,
  							 MEM_TYPE_PAGE_SHARED,
  							 NULL);
  			if (err < 0)
  				goto err_reg_mem;
  
  			/* Save original mem info as it can be overwritten */
  			rq->xdp_mem = rq->xdp_rxq.mem;
  		}

  
  		err = veth_napi_add(dev);
  		if (err)

  			goto err_rxq_reg;

  	}

  	for (i = 0; i < dev->real_num_rx_queues; i++)
  		rcu_assign_pointer(priv->rq[i].xdp_prog, priv->_xdp_prog);

  
  	return 0;

  err_reg_mem:
  	xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);
  err_rxq_reg:
  	for (i--; i >= 0; i--)
  		xdp_rxq_info_unreg(&priv->rq[i].xdp_rxq);

  
  	return err;
  }
  
  static void veth_disable_xdp(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);

  	int i;

  	for (i = 0; i < dev->real_num_rx_queues; i++)
  		rcu_assign_pointer(priv->rq[i].xdp_prog, NULL);

  	veth_napi_del(dev);

  	for (i = 0; i < dev->real_num_rx_queues; i++) {
  		struct veth_rq *rq = &priv->rq[i];
  
  		rq->xdp_rxq.mem = rq->xdp_mem;
  		xdp_rxq_info_unreg(&rq->xdp_rxq);
  	}

  }

  static int veth_open(struct net_device *dev)
  {

  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer = rtnl_dereference(priv->peer);

  	int err;

  	if (!peer)

  		return -ENOTCONN;

  	if (priv->_xdp_prog) {
  		err = veth_enable_xdp(dev);
  		if (err)
  			return err;
  	}

  	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);

  	if (priv->_xdp_prog)
  		veth_disable_xdp(dev);

  	return 0;
  }

  static int is_valid_veth_mtu(int mtu)

  {

  	return mtu >= ETH_MIN_MTU && mtu <= ETH_MAX_MTU;

  }

  static int veth_alloc_queues(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	int i;
  
  	priv->rq = kcalloc(dev->num_rx_queues, sizeof(*priv->rq), GFP_KERNEL);
  	if (!priv->rq)
  		return -ENOMEM;

  	for (i = 0; i < dev->num_rx_queues; i++) {

  		priv->rq[i].dev = dev;

  		u64_stats_init(&priv->rq[i].stats.syncp);
  	}

  
  	return 0;
  }
  
  static void veth_free_queues(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  
  	kfree(priv->rq);
  }

  static int veth_dev_init(struct net_device *dev)
  {

  	int err;

  	dev->lstats = netdev_alloc_pcpu_stats(struct pcpu_lstats);
  	if (!dev->lstats)

  		return -ENOMEM;

  
  	err = veth_alloc_queues(dev);
  	if (err) {

  		free_percpu(dev->lstats);

  		return err;
  	}

  	return 0;
  }

  static void veth_dev_free(struct net_device *dev)
  {

  	veth_free_queues(dev);

  	free_percpu(dev->lstats);

  }

  #ifdef CONFIG_NET_POLL_CONTROLLER
  static void veth_poll_controller(struct net_device *dev)
  {
  	/* veth only receives frames when its peer sends one

  	 * Since it has nothing to do with disabling irqs, we are guaranteed

  	 * never to have pending data when we poll for it so
  	 * there is nothing to do here.
  	 *
  	 * We need this though so netpoll recognizes us as an interface that
  	 * supports polling, which enables bridge devices in virt setups to
  	 * still use netconsole
  	 */
  }
  #endif	/* CONFIG_NET_POLL_CONTROLLER */

  static int veth_get_iflink(const struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer;
  	int iflink;
  
  	rcu_read_lock();
  	peer = rcu_dereference(priv->peer);
  	iflink = peer ? peer->ifindex : 0;
  	rcu_read_unlock();
  
  	return iflink;
  }

  static netdev_features_t veth_fix_features(struct net_device *dev,
  					   netdev_features_t features)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer;
  
  	peer = rtnl_dereference(priv->peer);
  	if (peer) {
  		struct veth_priv *peer_priv = netdev_priv(peer);
  
  		if (peer_priv->_xdp_prog)
  			features &= ~NETIF_F_GSO_SOFTWARE;
  	}
  
  	return features;
  }

  static void veth_set_rx_headroom(struct net_device *dev, int new_hr)
  {
  	struct veth_priv *peer_priv, *priv = netdev_priv(dev);
  	struct net_device *peer;
  
  	if (new_hr < 0)
  		new_hr = 0;
  
  	rcu_read_lock();
  	peer = rcu_dereference(priv->peer);
  	if (unlikely(!peer))
  		goto out;
  
  	peer_priv = netdev_priv(peer);
  	priv->requested_headroom = new_hr;
  	new_hr = max(priv->requested_headroom, peer_priv->requested_headroom);
  	dev->needed_headroom = new_hr;
  	peer->needed_headroom = new_hr;
  
  out:
  	rcu_read_unlock();
  }

  static int veth_xdp_set(struct net_device *dev, struct bpf_prog *prog,
  			struct netlink_ext_ack *extack)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct bpf_prog *old_prog;
  	struct net_device *peer;

  	unsigned int max_mtu;

  	int err;
  
  	old_prog = priv->_xdp_prog;
  	priv->_xdp_prog = prog;
  	peer = rtnl_dereference(priv->peer);
  
  	if (prog) {
  		if (!peer) {
  			NL_SET_ERR_MSG_MOD(extack, "Cannot set XDP when peer is detached");
  			err = -ENOTCONN;
  			goto err;
  		}

  		max_mtu = PAGE_SIZE - VETH_XDP_HEADROOM -
  			  peer->hard_header_len -
  			  SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
  		if (peer->mtu > max_mtu) {
  			NL_SET_ERR_MSG_MOD(extack, "Peer MTU is too large to set XDP");
  			err = -ERANGE;
  			goto err;
  		}

  		if (dev->real_num_rx_queues < peer->real_num_tx_queues) {
  			NL_SET_ERR_MSG_MOD(extack, "XDP expects number of rx queues not less than peer tx queues");
  			err = -ENOSPC;
  			goto err;
  		}

  		if (dev->flags & IFF_UP) {
  			err = veth_enable_xdp(dev);
  			if (err) {
  				NL_SET_ERR_MSG_MOD(extack, "Setup for XDP failed");
  				goto err;
  			}
  		}

  
  		if (!old_prog) {
  			peer->hw_features &= ~NETIF_F_GSO_SOFTWARE;
  			peer->max_mtu = max_mtu;
  		}

  	}
  
  	if (old_prog) {

  		if (!prog) {
  			if (dev->flags & IFF_UP)
  				veth_disable_xdp(dev);
  
  			if (peer) {
  				peer->hw_features |= NETIF_F_GSO_SOFTWARE;
  				peer->max_mtu = ETH_MAX_MTU;
  			}
  		}

  		bpf_prog_put(old_prog);
  	}

  	if ((!!old_prog ^ !!prog) && peer)
  		netdev_update_features(peer);

  	return 0;
  err:
  	priv->_xdp_prog = old_prog;
  
  	return err;
  }

  static int veth_xdp(struct net_device *dev, struct netdev_bpf *xdp)
  {
  	switch (xdp->command) {
  	case XDP_SETUP_PROG:
  		return veth_xdp_set(dev, xdp->prog, xdp->extack);

  	default:
  		return -EINVAL;
  	}
  }

  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_get_stats64     = veth_get_stats64,

  	.ndo_set_rx_mode     = veth_set_multicast_list,

  	.ndo_set_mac_address = eth_mac_addr,

  #ifdef CONFIG_NET_POLL_CONTROLLER
  	.ndo_poll_controller	= veth_poll_controller,
  #endif

  	.ndo_get_iflink		= veth_get_iflink,

  	.ndo_fix_features	= veth_fix_features,

  	.ndo_features_check	= passthru_features_check,

  	.ndo_set_rx_headroom	= veth_set_rx_headroom,

  	.ndo_bpf		= veth_xdp,

  	.ndo_xdp_xmit		= veth_ndo_xdp_xmit,

  	.ndo_get_peer_dev	= veth_peer_dev,

  };

  #define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HW_CSUM | \

  		       NETIF_F_RXCSUM | NETIF_F_SCTP_CRC | NETIF_F_HIGHDMA | \

  		       NETIF_F_GSO_SOFTWARE | NETIF_F_GSO_ENCAP_ALL | \

  		       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->priv_flags |= IFF_NO_QUEUE;

  	dev->priv_flags |= IFF_PHONY_HEADROOM;

  	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->needs_free_netdev = true;
  	dev->priv_destructor = veth_dev_free;

  	dev->max_mtu = ETH_MAX_MTU;

  	dev->hw_features = VETH_FEATURES;

  	dev->hw_enc_features = VETH_FEATURES;

  	dev->mpls_features = NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE;

  }
  
  /*
   * netlink interface
   */

  static int veth_validate(struct nlattr *tb[], struct nlattr *data[],
  			 struct netlink_ext_ack *extack)

  {
  	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[],
  			struct netlink_ext_ack *extack)

  {

  	int err;

  	struct net_device *peer;
  	struct veth_priv *priv;
  	char ifname[IFNAMSIZ];
  	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;

  	unsigned char name_assign_type;

  	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 = rtnl_nla_parse_ifla(peer_tb,
  					  nla_data(nla_peer) + sizeof(struct ifinfomsg),

  					  nla_len(nla_peer) - sizeof(struct ifinfomsg),
  					  NULL);

  		if (err < 0)
  			return err;

  		err = veth_validate(peer_tb, NULL, extack);

  		if (err < 0)
  			return err;
  
  		tbp = peer_tb;

  	} else {
  		ifmp = NULL;

  		tbp = tb;

  	}

  	if (ifmp && tbp[IFLA_IFNAME]) {

  		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);

  		name_assign_type = NET_NAME_USER;
  	} else {

  		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");

  		name_assign_type = NET_NAME_ENUM;
  	}

  	net = rtnl_link_get_net(src_net, tbp);
  	if (IS_ERR(net))
  		return PTR_ERR(net);

  	peer = rtnl_create_link(net, ifname, name_assign_type,

  				&veth_link_ops, tbp, extack);

  	if (IS_ERR(peer)) {
  		put_net(net);

  		return PTR_ERR(peer);

  	}

  	if (!ifmp || !tbp[IFLA_ADDRESS])

  		eth_hw_addr_random(peer);

  
  	if (ifmp && (dev->ifindex != 0))
  		peer->ifindex = ifmp->ifi_index;

  	peer->gso_max_size = dev->gso_max_size;
  	peer->gso_max_segs = dev->gso_max_segs;

  	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 net *veth_get_link_net(const struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  	struct net_device *peer = rtnl_dereference(priv->peer);
  
  	return peer ? dev_net(peer) : dev_net(dev);
  }

  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,

  	.get_link_net	= veth_get_link_net,

  };
  
  /*
   * 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);