[PATCH 0/2] Virtual ethernet device (v3)

[PATCH 0/2] Virtual ethernet device (v3)

[Pavel Emelianov]

Veth stands for Virtual ETHernet. It is a simple tunnel driver
that works at the link layer and looks like a pair of ethernet
devices interconnected with each other.

Mainly it allows to communicate between network namespaces but
it can be used as is as well.

Eric recently sent a similar driver called etun with the sysfs
interface. This implementation uses another interface - the 
RTM_NRELINK message introduced by Patric.

The newlink callback is organized that way to make it easy to 
create the peer device in the separate namespace when we have 
them in kernel.

Changes from v.2.1:
 * Made the generic routine for link creation to be used
   by veth driver, any other tunnel driver that needs to
   create several devices at once and rtnl_newlink() code.

Changes from v.2:
 * Rebase over latest netdev tree. No actual changes;
 * Small code rework.

Changes from v.1:
 * percpu statistics;
 * standard convention for nla policy names;
 * module alias added;
 * xmit function fixes noticed by Patric;
 * code cleanup.

The patch for an ip utility is also provided.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Cc: Patrick McHardy <kaber@trash.net>

[PATCH 1/2] Introduce the generic rtnl_create_link()

[Pavel Emelianov]

This routine gets the parsed rtnl attributes and creates a new
link with generic info (IFLA_LINKINFO policy). Its intention
is to help the drivers, that need to create several links at 
once (like VETH).

This is nothing but a copy-paste-ed part of rtnl_newlink() function
that is responsible for creation of new device.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

 include/net/rtnetlink.h |    4 ++
 net/core/rtnetlink.c    |   83 ++++++++++++++++++++++++++++++------------------
 2 files changed, 57 insertions(+), 30 deletions(-)

diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index 3861c05..8218288 100644
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -78,6 +78,10 @@ extern void	__rtnl_link_unregister(struc
 extern int	rtnl_link_register(struct rtnl_link_ops *ops);
 extern void	rtnl_link_unregister(struct rtnl_link_ops *ops);
 
+extern struct net_device *rtnl_create_link(char *ifname,
+		const struct rtnl_link_ops *ops, struct nlattr *tb[]);
+extern const struct nla_policy ifla_policy[IFLA_MAX+1];
+
 #define MODULE_ALIAS_RTNL_LINK(kind) MODULE_ALIAS("rtnl-link-" kind)
 
 #endif
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 864cbdf..02e00e8 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -714,7 +714,7 @@ cont:
 	return skb->len;
 }
 
-static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
+const struct nla_policy ifla_policy[IFLA_MAX+1] = {
 	[IFLA_IFNAME]		= { .type = NLA_STRING, .len = IFNAMSIZ-1 },
 	[IFLA_ADDRESS]		= { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
 	[IFLA_BROADCAST]	= { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
@@ -941,6 +941,50 @@ static int rtnl_dellink(struct sk_buff *
 	return 0;
 }
 
+struct net_device *rtnl_create_link(char *ifname,
+		const struct rtnl_link_ops *ops, struct nlattr *tb[])
+{
+	int err;
+	struct net_device *dev;
+
+	err = -ENOMEM;
+	dev = alloc_netdev(ops->priv_size, ifname, ops->setup);
+	if (!dev)
+		goto err;
+
+	if (strchr(dev->name, '%')) {
+		err = dev_alloc_name(dev, dev->name);
+		if (err < 0)
+			goto err_free;
+	}
+
+	dev->rtnl_link_ops = ops;
+
+	if (tb[IFLA_MTU])
+		dev->mtu = nla_get_u32(tb[IFLA_MTU]);
+	if (tb[IFLA_ADDRESS])
+		memcpy(dev->dev_addr, nla_data(tb[IFLA_ADDRESS]),
+				nla_len(tb[IFLA_ADDRESS]));
+	if (tb[IFLA_BROADCAST])
+		memcpy(dev->broadcast, nla_data(tb[IFLA_BROADCAST]),
+				nla_len(tb[IFLA_BROADCAST]));
+	if (tb[IFLA_TXQLEN])
+		dev->tx_queue_len = nla_get_u32(tb[IFLA_TXQLEN]);
+	if (tb[IFLA_WEIGHT])
+		dev->weight = nla_get_u32(tb[IFLA_WEIGHT]);
+	if (tb[IFLA_OPERSTATE])
+		set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
+	if (tb[IFLA_LINKMODE])
+		dev->link_mode = nla_get_u8(tb[IFLA_LINKMODE]);
+
+	return dev;
+
+err_free:
+	free_netdev(dev);
+err:
+	return ERR_PTR(err);
+}
+
 static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 {
 	const struct rtnl_link_ops *ops;
@@ -1051,40 +1095,17 @@ replay:
 
 		if (!ifname[0])
 			snprintf(ifname, IFNAMSIZ, "%s%%d", ops->kind);
-		dev = alloc_netdev(ops->priv_size, ifname, ops->setup);
-		if (!dev)
-			return -ENOMEM;
-
-		if (strchr(dev->name, '%')) {
-			err = dev_alloc_name(dev, dev->name);
-			if (err < 0)
-				goto err_free;
-		}
-		dev->rtnl_link_ops = ops;
 
-		if (tb[IFLA_MTU])
-			dev->mtu = nla_get_u32(tb[IFLA_MTU]);
-		if (tb[IFLA_ADDRESS])
-			memcpy(dev->dev_addr, nla_data(tb[IFLA_ADDRESS]),
-			       nla_len(tb[IFLA_ADDRESS]));
-		if (tb[IFLA_BROADCAST])
-			memcpy(dev->broadcast, nla_data(tb[IFLA_BROADCAST]),
-			       nla_len(tb[IFLA_BROADCAST]));
-		if (tb[IFLA_TXQLEN])
-			dev->tx_queue_len = nla_get_u32(tb[IFLA_TXQLEN]);
-		if (tb[IFLA_WEIGHT])
-			dev->weight = nla_get_u32(tb[IFLA_WEIGHT]);
-		if (tb[IFLA_OPERSTATE])
-			set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
-		if (tb[IFLA_LINKMODE])
-			dev->link_mode = nla_get_u8(tb[IFLA_LINKMODE]);
+		dev = rtnl_create_link(ifname, ops, tb);
 
-		if (ops->newlink)
+		if (IS_ERR(dev))
+			err = PTR_ERR(dev);
+		else if (ops->newlink)
 			err = ops->newlink(dev, tb, data);
 		else
 			err = register_netdevice(dev);
-err_free:
-		if (err < 0)
+
+		if (err < 0 && !IS_ERR(dev))
 			free_netdev(dev);
 		return err;
 	}
@@ -1333,3 +1354,5 @@ EXPORT_SYMBOL(rtnl_unlock);
 EXPORT_SYMBOL(rtnl_unicast);
 EXPORT_SYMBOL(rtnl_notify);
 EXPORT_SYMBOL(rtnl_set_sk_err);
+EXPORT_SYMBOL(rtnl_create_link);
+EXPORT_SYMBOL(ifla_policy);

[PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Veth stands for Virtual ETHernet. It is a simple tunnel driver
that works at the link layer and looks like a pair of ethernet
devices interconnected with each other.

Mainly it allows to communicate between network namespaces but
it can be used as is as well.

The newlink callback is organized that way to make it easy to 
create the peer device in the separate namespace when we have 
them in kernel.

This implementation uses another interface - the RTM_NRELINK
message introduced by Patric.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

 drivers/net/Kconfig  |    6 
 drivers/net/Makefile |    1 
 drivers/net/veth.c   |  426 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/net/veth.h   |   12 +
 4 files changed, 445 insertions(+)

diff-tree 293fc37c28eee0a27e19179ab0d809460c73eced (from 15028aad00ddf241581fbe74a02ec89cbb28d35d)
Author: Pavel <pavel@xemulnb.sw.ru>
Date:   Thu Jul 12 13:05:44 2007 +0400

    Veth support

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index d4e39ff..7bdc6e3 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -124,6 +124,12 @@ config TUN
 
 	  If you don't know what to use this for, you don't need it.
 
+config VETH
+	tristate "Virtual ethernet device"
+	---help---
+	  The device is an ethernet tunnel. Devices are created in pairs. When
+	  one end receives the packet it appears on its pair and vice versa.
+
 config NET_SB1000
 	tristate "General Instruments Surfboard 1000"
 	depends on PNP
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index a2241e6..d7b1103 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -189,6 +189,7 @@ obj-$(CONFIG_MACSONIC) += macsonic.o
 obj-$(CONFIG_MACMACE) += macmace.o
 obj-$(CONFIG_MAC89x0) += mac89x0.o
 obj-$(CONFIG_TUN) += tun.o
+obj-$(CONFIG_VETH) += veth.o
 obj-$(CONFIG_NET_NETX) += netx-eth.o
 obj-$(CONFIG_DL2K) += dl2k.o
 obj-$(CONFIG_R8169) += r8169.o
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
new file mode 100644
index 0000000..caa7b62
--- /dev/null
+++ b/drivers/net/veth.c
@@ -0,0 +1,426 @@
+/*
+ *  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/list.h>
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/etherdevice.h>
+
+#include <net/dst.h>
+#include <net/xfrm.h>
+#include <net/veth.h>
+
+#define DRV_NAME	"veth"
+#define DRV_VERSION	"1.0"
+
+struct veth_net_stats {
+	unsigned long	rx_packets;
+	unsigned long	tx_packets;
+	unsigned long	rx_bytes;
+	unsigned long	tx_bytes;
+	unsigned long	tx_dropped;
+};
+
+struct veth_priv {
+	struct net_device *peer;
+	struct net_device *dev;
+	struct list_head list;
+	struct veth_net_stats *stats;
+	unsigned ip_summed;
+};
+
+static LIST_HEAD(veth_list);
+
+/*
+ * 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;
+	cmd->speed		= 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)
+{
+	strcpy(info->driver, DRV_NAME);
+	strcpy(info->version, DRV_VERSION);
+	strcpy(info->fw_version, "N/A");
+}
+
+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_stats_count(struct net_device *dev)
+{
+	return ARRAY_SIZE(ethtool_stats_keys);
+}
+
+static void veth_get_ethtool_stats(struct net_device *dev,
+		struct ethtool_stats *stats, u64 *data)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	data[0] = priv->peer->ifindex;
+}
+
+static u32 veth_get_rx_csum(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	return priv->ip_summed == CHECKSUM_UNNECESSARY;
+}
+
+static int veth_set_rx_csum(struct net_device *dev, u32 data)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	priv->ip_summed = data ? CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
+	return 0;
+}
+
+static u32 veth_get_tx_csum(struct net_device *dev)
+{
+	return (dev->features & NETIF_F_NO_CSUM) != 0;
+}
+
+static int veth_set_tx_csum(struct net_device *dev, u32 data)
+{
+	if (data)
+		dev->features |= NETIF_F_NO_CSUM;
+	else
+		dev->features &= ~NETIF_F_NO_CSUM;
+	return 0;
+}
+
+static struct ethtool_ops veth_ethtool_ops = {
+	.get_settings		= veth_get_settings,
+	.get_drvinfo		= veth_get_drvinfo,
+	.get_link		= ethtool_op_get_link,
+	.get_rx_csum		= veth_get_rx_csum,
+	.set_rx_csum		= veth_set_rx_csum,
+	.get_tx_csum		= veth_get_tx_csum,
+	.set_tx_csum		= veth_set_tx_csum,
+	.get_sg			= ethtool_op_get_sg,
+	.set_sg			= ethtool_op_set_sg,
+	.get_strings		= veth_get_strings,
+	.get_stats_count	= veth_get_stats_count,
+	.get_ethtool_stats	= veth_get_ethtool_stats,
+	.get_perm_addr		= ethtool_op_get_perm_addr,
+};
+
+/*
+ * xmit
+ */
+
+static int veth_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device *rcv = NULL;
+	struct veth_priv *priv, *rcv_priv;
+	struct veth_net_stats *stats;
+	int length, cpu;
+
+	skb_orphan(skb);
+
+	priv = netdev_priv(dev);
+	rcv = priv->peer;
+	rcv_priv = netdev_priv(rcv);
+
+	cpu = smp_processor_id();
+	stats = per_cpu_ptr(priv->stats, cpu);
+
+	if (!(rcv->flags & IFF_UP))
+		goto outf;
+
+	skb->pkt_type = PACKET_HOST;
+	skb->protocol = eth_type_trans(skb, rcv);
+	if (dev->features & NETIF_F_NO_CSUM)
+		skb->ip_summed = rcv_priv->ip_summed;
+
+	dst_release(skb->dst);
+	skb->dst = NULL;
+	skb->mark = 0;
+	secpath_reset(skb);
+	nf_reset(skb);
+
+	length = skb->len;
+
+	stats->tx_bytes += length;
+	stats->tx_packets++;
+
+	stats = per_cpu_ptr(rcv_priv->stats, cpu);
+	stats->rx_bytes += length;
+	stats->rx_packets++;
+
+	netif_rx(skb);
+	return 0;
+
+outf:
+	kfree_skb(skb);
+	stats->tx_dropped++;
+	return 0;
+}
+
+/*
+ * general routines
+ */
+
+static struct net_device_stats *veth_get_stats(struct net_device *dev)
+{
+	struct veth_priv *priv;
+	struct net_device_stats *dev_stats;
+	int cpu;
+	struct veth_net_stats *stats;
+	
+	priv = netdev_priv(dev);
+	dev_stats = &dev->stats;
+
+	dev_stats->rx_packets = 0;
+	dev_stats->tx_packets = 0;
+	dev_stats->rx_bytes = 0;
+	dev_stats->tx_bytes = 0;
+	dev_stats->tx_dropped = 0;
+
+	for_each_online_cpu(cpu) {
+		stats = per_cpu_ptr(priv->stats, cpu);
+
+		dev_stats->rx_packets += stats->rx_packets;
+		dev_stats->tx_packets += stats->tx_packets;
+		dev_stats->rx_bytes += stats->rx_bytes;
+		dev_stats->tx_bytes += stats->tx_bytes;
+		dev_stats->tx_dropped += stats->tx_dropped;
+	}
+
+	return dev_stats;
+}
+
+static int veth_open(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	if (priv->peer == NULL)
+		return -ENOTCONN;
+
+	if (priv->peer->flags & IFF_UP) {
+		netif_carrier_on(dev);
+		netif_carrier_on(priv->peer);
+	}
+	return 0;
+}
+
+static int veth_close(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	if (netif_carrier_ok(dev)) {
+		priv = netdev_priv(dev);
+		netif_carrier_off(dev);
+		netif_carrier_off(priv->peer);
+	}
+	return 0;
+}
+
+static int veth_dev_init(struct net_device *dev)
+{
+	struct veth_net_stats *stats;
+	struct veth_priv *priv;
+
+	stats = alloc_percpu(struct veth_net_stats);
+	if (stats == NULL)
+		return -ENOMEM;
+
+	priv = netdev_priv(dev);
+	priv->stats = stats;
+	return 0;
+}
+
+static void veth_dev_free(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	free_percpu(priv->stats);
+	free_netdev(dev);
+}
+
+static void veth_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+
+	dev->hard_start_xmit = veth_xmit;
+	dev->get_stats = veth_get_stats;
+	dev->open = veth_open;
+	dev->stop = veth_close;
+	dev->ethtool_ops = &veth_ethtool_ops;
+	dev->features |= NETIF_F_LLTX;
+	dev->init = veth_dev_init;
+	dev->destructor = veth_dev_free;
+	netif_carrier_off(dev);
+}
+
+/*
+ * netlink interface
+ */
+
+static struct rtnl_link_ops veth_link_ops;
+
+static int veth_newlink(struct net_device *dev,
+			 struct nlattr *tb[], struct nlattr *data[])
+{
+	int err;
+	struct net_device *peer;
+	struct veth_priv *priv;
+	char ifname[IFNAMSIZ];
+
+	/*
+	 * prepare the devices info
+	 */
+
+	if (tb[IFLA_ADDRESS] == NULL)
+		random_ether_addr(dev->dev_addr);
+
+	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
+		err = nla_parse_nested(tb, IFLA_INFO_MAX,
+				data[VETH_INFO_PEER], ifla_policy);
+		if (err < 0)
+			return err;
+	}
+
+	if (tb[IFLA_IFNAME])
+		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
+	else
+		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
+
+	peer = rtnl_create_link(ifname, &veth_link_ops, tb);
+	if (IS_ERR(peer))
+		return PTR_ERR(peer);
+
+	if (tb[IFLA_ADDRESS] == NULL)
+		random_ether_addr(peer->dev_addr);
+
+	/*
+	 * register devices
+	 */
+
+	err = register_netdevice(peer);
+	if (err < 0)
+		goto err_register_peer;
+
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto err_register_dev;
+
+	/*
+	 * tie the deviced together
+	 */
+
+	priv = netdev_priv(dev);
+	priv->dev = dev;
+	priv->peer = peer;
+	list_add(&priv->list, &veth_list);
+
+	priv = netdev_priv(peer);
+	priv->dev = peer;
+	priv->peer = dev;
+	INIT_LIST_HEAD(&priv->list);
+	return 0;
+
+err_register_dev:
+	unregister_netdevice(peer);
+	return err;
+
+err_register_peer:
+	free_netdev(peer);
+	return err;
+}
+
+static void veth_dellink(struct net_device *dev)
+{
+	struct veth_priv *priv;
+	struct net_device *peer;
+
+	priv = netdev_priv(dev);
+	peer = priv->peer;
+
+	if (!list_empty(&priv->list))
+		list_del(&priv->list);
+
+	priv = netdev_priv(peer);
+	if (!list_empty(&priv->list))
+		list_del(&priv->list);
+
+	unregister_netdevice(dev);
+	unregister_netdevice(peer);
+}
+
+static const struct nla_policy veth_policy[VETH_INFO_MAX + 1];
+
+static struct rtnl_link_ops veth_link_ops = {
+	.kind		= DRV_NAME,
+	.priv_size	= sizeof(struct veth_priv),
+	.setup		= veth_setup,
+	.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)
+{
+	struct veth_priv *priv, *next;
+
+	rtnl_lock();
+	__rtnl_link_unregister(&veth_link_ops);
+
+	list_for_each_entry_safe(priv, next, &veth_list, list)
+		veth_dellink(priv->dev);
+	rtnl_unlock();
+}
+
+module_init(veth_init);
+module_exit(veth_exit);
+
+MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_RTNL_LINK(DRV_NAME);
diff --git a/include/net/veth.h b/include/net/veth.h
new file mode 100644
index 0000000..aa2e6f9
--- /dev/null
+++ b/include/net/veth.h
@@ -0,0 +1,12 @@
+#ifndef __NET_VETH_H__
+#define __NET_VETH_H__
+
+enum {
+	VETH_INFO_UNSPEC,
+	VETH_INFO_PEER,
+
+	__VETH_INFO_MAX
+#define VETH_INFO_MAX	(__VETH_INFO_MAX - 1)
+};
+
+#endif

[PATCH 0/2] Module for ip utility to support veth device (v.3)

[Pavel Emelianov]

The usage is
# ip link add [name] type veth [peer <name>] [mac <mac>] [peer_mac <mac>]

This consists of two parts:
1/2 makes some copy-paste changes in ip/iplink.c for generic CLI
attributes parsing,
2/2 the module itself.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

[PATCH 1/2] Intruduce iplink_parse() routine

[Pavel Emelianov]

This routine parses CLI attributes, describing generic
link parameters such as name, address, etc.

This is mostly copy-pasted from iplink_modify().

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

 include/utils.h |    3 +
 ip/iplink.c     |  127 ++++++++++++++++++++++++++++++++------------------------
 2 files changed, 76 insertions(+), 54 deletions(-)

diff --git a/include/utils.h b/include/utils.h
index a3fd335..3fd851d 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -146,4 +146,7 @@ extern int cmdlineno;
 extern size_t getcmdline(char **line, size_t *len, FILE *in);
 extern int makeargs(char *line, char *argv[], int maxargs);
 
+struct iplink_req;
+int iplink_parse(int argc, char **argv, struct iplink_req *req,
+		char **name, char **type, char **link, char **dev);
 #endif /* __UTILS_H__ */
diff --git a/ip/iplink.c b/ip/iplink.c
index cfacdab..9ee269c 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -142,140 +142,159 @@ static int iplink_have_newlink(void)
 }
 #endif /* ! IPLINK_IOCTL_COMPAT */
 
-static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
+struct iplink_req {
+	struct nlmsghdr		n;
+	struct ifinfomsg	i;
+	char			buf[1024];
+};
+
+int iplink_parse(int argc, char **argv, struct iplink_req *req,
+		char **name, char **type, char **link, char **dev)
 {
+	int ret, len;
+	char abuf[32];
 	int qlen = -1;
 	int mtu = -1;
-	int len;
-	char abuf[32];
-	char *dev = NULL;
-	char *name = NULL;
-	char *link = NULL;
-	char *type = NULL;
-	struct link_util *lu = NULL;
-	struct {
-		struct nlmsghdr		n;
-		struct ifinfomsg	i;
-		char			buf[1024];
-	} req;
 
-	memset(&req, 0, sizeof(req));
-
-	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
-	req.n.nlmsg_flags = NLM_F_REQUEST|flags;
-	req.n.nlmsg_type = cmd;
-	req.i.ifi_family = preferred_family;
+	ret = argc;
 
 	while (argc > 0) {
 		if (strcmp(*argv, "up") == 0) {
-			req.i.ifi_change |= IFF_UP;
-			req.i.ifi_flags |= IFF_UP;
+			req->i.ifi_change |= IFF_UP;
+			req->i.ifi_flags |= IFF_UP;
 		} else if (strcmp(*argv, "down") == 0) {
-			req.i.ifi_change |= IFF_UP;
-			req.i.ifi_flags &= ~IFF_UP;
+			req->i.ifi_change |= IFF_UP;
+			req->i.ifi_flags &= ~IFF_UP;
 		} else if (strcmp(*argv, "name") == 0) {
 			NEXT_ARG();
-			name = *argv;
+			*name = *argv;
 		} else if (matches(*argv, "link") == 0) {
 			NEXT_ARG();
-			link = *argv;
+			*link = *argv;
 		} else if (matches(*argv, "address") == 0) {
 			NEXT_ARG();
 			len = ll_addr_a2n(abuf, sizeof(abuf), *argv);
-			addattr_l(&req.n, sizeof(req), IFLA_ADDRESS, abuf, len);
+			addattr_l(&req->n, sizeof(req), IFLA_ADDRESS, abuf, len);
 		} else if (matches(*argv, "broadcast") == 0 ||
-			   strcmp(*argv, "brd") == 0) {
+				strcmp(*argv, "brd") == 0) {
 			NEXT_ARG();
 			len = ll_addr_a2n(abuf, sizeof(abuf), *argv);
-			addattr_l(&req.n, sizeof(req), IFLA_BROADCAST, abuf, len);
+			addattr_l(&req->n, sizeof(req), IFLA_BROADCAST, abuf, len);
 		} else if (matches(*argv, "txqueuelen") == 0 ||
-			   strcmp(*argv, "qlen") == 0 ||
-			   matches(*argv, "txqlen") == 0) {
+				strcmp(*argv, "qlen") == 0 ||
+				matches(*argv, "txqlen") == 0) {
 			NEXT_ARG();
 			if (qlen != -1)
 				duparg("txqueuelen", *argv);
 			if (get_integer(&qlen,  *argv, 0))
 				invarg("Invalid \"txqueuelen\" value\n", *argv);
-			addattr_l(&req.n, sizeof(req), IFLA_TXQLEN, &qlen, 4);
+			addattr_l(&req->n, sizeof(req), IFLA_TXQLEN, &qlen, 4);
 		} else if (strcmp(*argv, "mtu") == 0) {
 			NEXT_ARG();
 			if (mtu != -1)
 				duparg("mtu", *argv);
 			if (get_integer(&mtu, *argv, 0))
 				invarg("Invalid \"mtu\" value\n", *argv);
-			addattr_l(&req.n, sizeof(req), IFLA_MTU, &mtu, 4);
+			addattr_l(&req->n, sizeof(req), IFLA_MTU, &mtu, 4);
 		} else if (strcmp(*argv, "multicast") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_MULTICAST;
+			req->i.ifi_change |= IFF_MULTICAST;
 			if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags |= IFF_MULTICAST;
+				req->i.ifi_flags |= IFF_MULTICAST;
 			} else if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags &= ~IFF_MULTICAST;
+				req->i.ifi_flags &= ~IFF_MULTICAST;
 			} else
 				return on_off("multicast");
 		} else if (strcmp(*argv, "allmulticast") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_ALLMULTI;
+			req->i.ifi_change |= IFF_ALLMULTI;
 			if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags |= IFF_ALLMULTI;
+				req->i.ifi_flags |= IFF_ALLMULTI;
 			} else if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags &= ~IFF_ALLMULTI;
+				req->i.ifi_flags &= ~IFF_ALLMULTI;
 			} else
 				return on_off("allmulticast");
 		} else if (strcmp(*argv, "promisc") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_PROMISC;
+			req->i.ifi_change |= IFF_PROMISC;
 			if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags |= IFF_PROMISC;
+				req->i.ifi_flags |= IFF_PROMISC;
 			} else if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags &= ~IFF_PROMISC;
+				req->i.ifi_flags &= ~IFF_PROMISC;
 			} else
 				return on_off("promisc");
 		} else if (strcmp(*argv, "trailers") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_NOTRAILERS;
+			req->i.ifi_change |= IFF_NOTRAILERS;
 			if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags |= IFF_NOTRAILERS;
+				req->i.ifi_flags |= IFF_NOTRAILERS;
 			} else if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags &= ~IFF_NOTRAILERS;
+				req->i.ifi_flags &= ~IFF_NOTRAILERS;
 			} else
 				return on_off("trailers");
 		} else if (strcmp(*argv, "arp") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_NOARP;
+			req->i.ifi_change |= IFF_NOARP;
 			if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags &= ~IFF_NOARP;
+				req->i.ifi_flags &= ~IFF_NOARP;
 			} else if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags |= IFF_NOARP;
+				req->i.ifi_flags |= IFF_NOARP;
 			} else
 				return on_off("noarp");
 #ifdef IFF_DYNAMIC
 		} else if (matches(*argv, "dynamic") == 0) {
 			NEXT_ARG();
-			req.i.ifi_change |= IFF_DYNAMIC;
+			req->i.ifi_change |= IFF_DYNAMIC;
 			if (strcmp(*argv, "on") == 0) {
-				req.i.ifi_flags |= IFF_DYNAMIC;
+				req->i.ifi_flags |= IFF_DYNAMIC;
 			} else if (strcmp(*argv, "off") == 0) {
-				req.i.ifi_flags &= ~IFF_DYNAMIC;
+				req->i.ifi_flags &= ~IFF_DYNAMIC;
 			} else
 				return on_off("dynamic");
 #endif
 		} else if (matches(*argv, "type") == 0) {
 			NEXT_ARG();
-			type = *argv;
+			*type = *argv;
 			argc--; argv++;
 			break;
 		} else {
-                        if (strcmp(*argv, "dev") == 0) {
+			if (strcmp(*argv, "dev") == 0) {
 				NEXT_ARG();
 			}
-			if (dev)
+			if (*dev)
 				duparg2("dev", *argv);
-			dev = *argv;
+			*dev = *argv;
 		}
 		argc--; argv++;
 	}
 
+	return ret - argc;
+}
+
+static int iplink_modify(int cmd, unsigned int flags, int argc, char **argv)
+{
+	int len;
+	char *dev = NULL;
+	char *name = NULL;
+	char *link = NULL;
+	char *type = NULL;
+	struct link_util *lu = NULL;
+	struct iplink_req req;
+	int ret;
+
+	memset(&req, 0, sizeof(req));
+
+	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+	req.n.nlmsg_flags = NLM_F_REQUEST|flags;
+	req.n.nlmsg_type = cmd;
+	req.i.ifi_family = preferred_family;
+
+	ret = iplink_parse(argc, argv, &req, &name, &type, &link, &dev);
+	if (ret < 0)
+		return ret;
+
+	argc -= ret;
+	argv += ret;
 	ll_init_map(&rth);
 
 	if (type) {

[PATCH 2/2] Module for ip utility to support veth device

[Pavel Emelianov]

The link_veth.so itself.

The usage is
ip link add <name> type veth [peer ...]

where ... are the same options as in regular ip link add usage.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

 Makefile    |    6 +++++-
 link_veth.c |   60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 veth.h      |   12 ++++++++++++
 3 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/ip/Makefile b/ip/Makefile
index 9a5bfe3..b46bce3 100644
--- a/ip/Makefile
+++ b/ip/Makefile
@@ -8,8 +8,9 @@ RTMONOBJ=rtmon.o
 ALLOBJ=$(IPOBJ) $(RTMONOBJ)
 SCRIPTS=ifcfg rtpr routel routef
 TARGETS=ip rtmon
+LIBS=link_veth.so
 
-all: $(TARGETS) $(SCRIPTS)
+all: $(TARGETS) $(SCRIPTS) $(LIBS)
 
 ip: $(IPOBJ) $(LIBNETLINK) $(LIBUTIL)
 
@@ -24,3 +25,6 @@ clean:
 
 LDLIBS	+= -ldl
 LDFLAGS	+= -Wl,-export-dynamic
+
+%.so: %.c
+	$(CC) $(CFLAGS) -shared $< -o $@
diff --git a/ip/link_veth.c b/ip/link_veth.c
new file mode 100644
index 0000000..0ceab86
--- /dev/null
+++ b/ip/link_veth.c
@@ -0,0 +1,60 @@
+/*
+ * link_veth.c	veth driver module
+ *
+ *		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.
+ *
+ * Authors:	Pavel Emelianov <xemul@openvz.org>
+ *
+ */
+
+#include <string.h>
+
+#include "utils.h"
+#include "ip_common.h"
+#include "veth.h"
+
+#define	IFNAMSIZ	16
+
+static void usage(void)
+{
+	printf("Usage: ip link add ... type veth "
+			"[peer <peer-name>] [mac <mac>] [peer_mac <mac>]\n");
+}
+
+static int veth_parse_opt(struct link_util *lu, int argc, char **argv,
+		struct nlmsghdr *hdr)
+{
+	char *name, *type, *link, *dev;
+	int err, len;
+	struct rtattr * data = NLMSG_TAIL(hdr);
+
+	if (strcmp(argv[0], "peer") != 0) {
+		usage();
+		return -1;
+	}
+
+	addattr_l(hdr, 1024, VETH_INFO_PEER, NULL, 0);
+
+	err = iplink_parse(argc - 1, argv + 1, (struct iplink_req *)hdr,
+			&name, &type, &link, &dev);
+	if (err < 0)
+		return err;
+
+	if (name) {
+		len = strlen(name) + 1;
+		if (len > IFNAMSIZ)
+			invarg("\"name\" too long\n", *argv);
+		addattr_l(hdr, 1024, IFLA_IFNAME, name, len);
+	}
+
+	data->rta_len = (void *)NLMSG_TAIL(hdr) - (void *)data;
+	return argc - 1 - err;
+}
+
+struct link_util veth_link_util = {
+	.id = "veth",
+	.parse_opt = veth_parse_opt,
+};
diff --git a/ip/veth.h b/ip/veth.h
new file mode 100644
index 0000000..aa2e6f9
--- /dev/null
+++ b/ip/veth.h
@@ -0,0 +1,12 @@
+#ifndef __NET_VETH_H__
+#define __NET_VETH_H__
+
+enum {
+	VETH_INFO_UNSPEC,
+	VETH_INFO_PEER,
+
+	__VETH_INFO_MAX
+#define VETH_INFO_MAX	(__VETH_INFO_MAX - 1)
+};
+
+#endif

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> +static int veth_newlink(struct net_device *dev,
> +			 struct nlattr *tb[], struct nlattr *data[])
> +{
> +	int err;
> +	struct net_device *peer;
> +	struct veth_priv *priv;
> +	char ifname[IFNAMSIZ];
> +
> +	/*
> +	 * prepare the devices info
> +	 */
> +
> +	if (tb[IFLA_ADDRESS] == NULL)
> +		random_ether_addr(dev->dev_addr);
> +
> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
> +				data[VETH_INFO_PEER], ifla_policy);
> +		if (err < 0)
> +			return err;
> +	}


Not having a peer should be an error, no?

> +
> +	if (tb[IFLA_IFNAME])
> +		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
> +	else
> +		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");


Does this work? The other device is not registered at this time, so I
think the allocated names could clash ..

If it does work you could also perform name allocation in the
rtnl_create_link function.


> +
> +	peer = rtnl_create_link(ifname, &veth_link_ops, tb);
> +	if (IS_ERR(peer))
> +		return PTR_ERR(peer);
> +
> +	if (tb[IFLA_ADDRESS] == NULL)
> +		random_ether_addr(peer->dev_addr);
> +
> +	/*
> +	 * register devices
> +	 */
> +
> +	err = register_netdevice(peer);
> +	if (err < 0)
> +		goto err_register_peer;
> +
> +	err = register_netdevice(dev);
> +	if (err < 0)
> +		goto err_register_dev;
> +
> +	/*
> +	 * tie the deviced together
> +	 */
> +
> +	priv = netdev_priv(dev);
> +	priv->dev = dev;
> +	priv->peer = peer;
> +	list_add(&priv->list, &veth_list);
> +
> +	priv = netdev_priv(peer);
> +	priv->dev = peer;
> +	priv->peer = dev;
> +	INIT_LIST_HEAD(&priv->list);
> +	return 0;
> +
> +err_register_dev:
> +	unregister_netdevice(peer);
> +	return err;
> +
> +err_register_peer:
> +	free_netdev(peer);
> +	return err;
> +}

> +static __exit void veth_exit(void)
> +{
> +	struct veth_priv *priv, *next;
> +
> +	rtnl_lock();
> +	__rtnl_link_unregister(&veth_link_ops);
> +
> +	list_for_each_entry_safe(priv, next, &veth_list, list)
> +		veth_dellink(priv->dev);
> +	rtnl_unlock();


Devices are unregistered automatically through the dellink function,
rtnl_link_unregister(..) is enough.

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> +static int veth_newlink(struct net_device *dev,
>> +			 struct nlattr *tb[], struct nlattr *data[])
>> +{
>> +	int err;
>> +	struct net_device *peer;
>> +	struct veth_priv *priv;
>> +	char ifname[IFNAMSIZ];
>> +
>> +	/*
>> +	 * prepare the devices info
>> +	 */
>> +
>> +	if (tb[IFLA_ADDRESS] == NULL)
>> +		random_ether_addr(dev->dev_addr);
>> +
>> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>> +				data[VETH_INFO_PEER], ifla_policy);
>> +		if (err < 0)
>> +			return err;
>> +	}
> 
> 
> Not having a peer should be an error, no?

No. That's the intention - if the user doesn't specify "peer" in the
command line then two _identical_ devices are created. Of course, if
he specifies one name - there'll be a collision, but one can say
"my_own_veth_number_%d" and everything will be ok. Or just use the 
default name provided. E.g. "ip link add type veth" will send a packet
with data[VETH_INFO_PEER} == NULL, but this is OK! User just wants a 
default tunnel and he will get it :)

Does this answer your second comment below?

>> +
>> +	if (tb[IFLA_IFNAME])
>> +		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
>> +	else
>> +		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
> 
> 
> Does this work? The other device is not registered at this time, so I
> think the allocated names could clash ..
> 
> If it does work you could also perform name allocation in the
> rtnl_create_link function.
> 
> 
>> +
>> +	peer = rtnl_create_link(ifname, &veth_link_ops, tb);
>> +	if (IS_ERR(peer))
>> +		return PTR_ERR(peer);
>> +
>> +	if (tb[IFLA_ADDRESS] == NULL)
>> +		random_ether_addr(peer->dev_addr);
>> +
>> +	/*
>> +	 * register devices
>> +	 */
>> +
>> +	err = register_netdevice(peer);
>> +	if (err < 0)
>> +		goto err_register_peer;
>> +
>> +	err = register_netdevice(dev);
>> +	if (err < 0)
>> +		goto err_register_dev;
>> +
>> +	/*
>> +	 * tie the deviced together
>> +	 */
>> +
>> +	priv = netdev_priv(dev);
>> +	priv->dev = dev;
>> +	priv->peer = peer;
>> +	list_add(&priv->list, &veth_list);
>> +
>> +	priv = netdev_priv(peer);
>> +	priv->dev = peer;
>> +	priv->peer = dev;
>> +	INIT_LIST_HEAD(&priv->list);
>> +	return 0;
>> +
>> +err_register_dev:
>> +	unregister_netdevice(peer);
>> +	return err;
>> +
>> +err_register_peer:
>> +	free_netdev(peer);
>> +	return err;
>> +}
> 
>> +static __exit void veth_exit(void)
>> +{
>> +	struct veth_priv *priv, *next;
>> +
>> +	rtnl_lock();
>> +	__rtnl_link_unregister(&veth_link_ops);
>> +
>> +	list_for_each_entry_safe(priv, next, &veth_list, list)
>> +		veth_dellink(priv->dev);
>> +	rtnl_unlock();
> 
> 
> Devices are unregistered automatically through the dellink function,
> rtnl_link_unregister(..) is enough.

OK. This looks like a minor and not-significant comment, so
do I need to resend the patch or David is OK to take it and
I will send an incremental one?

Thanks,
Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> +static int veth_newlink(struct net_device *dev,
>> +			 struct nlattr *tb[], struct nlattr *data[])
>> +{
>> +	int err;
>> +	struct net_device *peer;
>> +	struct veth_priv *priv;
>> +	char ifname[IFNAMSIZ];
>> +
>> +	/*
>> +	 * prepare the devices info
>> +	 */
>> +
>> +	if (tb[IFLA_ADDRESS] == NULL)
>> +		random_ether_addr(dev->dev_addr);
>> +
>> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>> +				data[VETH_INFO_PEER], ifla_policy);
>> +		if (err < 0)
>> +			return err;
>> +	}
> 
> 
> Not having a peer should be an error, no?
> 
>> +
>> +	if (tb[IFLA_IFNAME])
>> +		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
>> +	else
>> +		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
> 
> 
> Does this work? The other device is not registered at this time, so I
> think the allocated names could clash ..

Oh! And one more thing, I've just thought about - even two devices with
similar name would be ok when we have a namespaces and one of the ends of
this tunnel is to be in some other namespace rather that the init one.

> If it does work you could also perform name allocation in the
> rtnl_create_link function.
> 
> 
>> +
>> +	peer = rtnl_create_link(ifname, &veth_link_ops, tb);
>> +	if (IS_ERR(peer))
>> +		return PTR_ERR(peer);
>> +
>> +	if (tb[IFLA_ADDRESS] == NULL)
>> +		random_ether_addr(peer->dev_addr);
>> +
>> +	/*
>> +	 * register devices
>> +	 */
>> +
>> +	err = register_netdevice(peer);
>> +	if (err < 0)
>> +		goto err_register_peer;
>> +
>> +	err = register_netdevice(dev);
>> +	if (err < 0)
>> +		goto err_register_dev;
>> +
>> +	/*
>> +	 * tie the deviced together
>> +	 */
>> +
>> +	priv = netdev_priv(dev);
>> +	priv->dev = dev;
>> +	priv->peer = peer;
>> +	list_add(&priv->list, &veth_list);
>> +
>> +	priv = netdev_priv(peer);
>> +	priv->dev = peer;
>> +	priv->peer = dev;
>> +	INIT_LIST_HEAD(&priv->list);
>> +	return 0;
>> +
>> +err_register_dev:
>> +	unregister_netdevice(peer);
>> +	return err;
>> +
>> +err_register_peer:
>> +	free_netdev(peer);
>> +	return err;
>> +}
> 
>> +static __exit void veth_exit(void)
>> +{
>> +	struct veth_priv *priv, *next;
>> +
>> +	rtnl_lock();
>> +	__rtnl_link_unregister(&veth_link_ops);
>> +
>> +	list_for_each_entry_safe(priv, next, &veth_list, list)
>> +		veth_dellink(priv->dev);
>> +	rtnl_unlock();
> 
> 
> Devices are unregistered automatically through the dellink function,
> rtnl_link_unregister(..) is enough.
> 

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> Patrick McHardy wrote:
> 
>>Pavel Emelianov wrote:
>>
>>>+static int veth_newlink(struct net_device *dev,
>>>+			 struct nlattr *tb[], struct nlattr *data[])
>>>+{
>>>+	int err;
>>>+	struct net_device *peer;
>>>+	struct veth_priv *priv;
>>>+	char ifname[IFNAMSIZ];
>>>+
>>>+	/*
>>>+	 * prepare the devices info
>>>+	 */
>>>+
>>>+	if (tb[IFLA_ADDRESS] == NULL)
>>>+		random_ether_addr(dev->dev_addr);
>>>+
>>>+	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>>>+		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>>>+				data[VETH_INFO_PEER], ifla_policy);
>>>+		if (err < 0)
>>>+			return err;
>>>+	}
>>
>>
>>Not having a peer should be an error, no?
> 
> 
> No. That's the intention - if the user doesn't specify "peer" in the
> command line then two _identical_ devices are created. Of course, if
> he specifies one name - there'll be a collision, but one can say
> "my_own_veth_number_%d" and everything will be ok. Or just use the 
> default name provided. E.g. "ip link add type veth" will send a packet
> with data[VETH_INFO_PEER} == NULL, but this is OK! User just wants a 
> default tunnel and he will get it :)

I see.

> Does this answer your second comment below?


No, to get unique names the sequence has to be:

dev_alloc_name
register_netdevice
dev_alloc_name
register_netdevice

But you have:

dev_alloc_name
dev_alloc_name (<- might allocate same name as first call)
register_netdevice
register_netdevice

>>>+static __exit void veth_exit(void)
>>>+{
>>>+	struct veth_priv *priv, *next;
>>>+
>>>+	rtnl_lock();
>>>+	__rtnl_link_unregister(&veth_link_ops);
>>>+
>>>+	list_for_each_entry_safe(priv, next, &veth_list, list)
>>>+		veth_dellink(priv->dev);
>>>+	rtnl_unlock();
>>
>>
>>Devices are unregistered automatically through the dellink function,
>>rtnl_link_unregister(..) is enough.
> 
> 
> OK. This looks like a minor and not-significant comment, so
> do I need to resend the patch or David is OK to take it and
> I will send an incremental one?


An incremental patch for this is fine I guess, your code is correct,
its merely a simplification.

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> Patrick McHardy wrote:
> 
>>>+
>>>+	if (tb[IFLA_IFNAME])
>>>+		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
>>>+	else
>>>+		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
>>
>>
>>Does this work? The other device is not registered at this time, so I
>>think the allocated names could clash ..
> 
> 
> Oh! And one more thing, I've just thought about - even two devices with
> similar name would be ok when we have a namespaces and one of the ends of
> this tunnel is to be in some other namespace rather that the init one.


Yes, but we don't have network namespaces yet. Which brings up another
question: is this driver of any use without namespaces?

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> Patrick McHardy wrote:
>>
>>> Pavel Emelianov wrote:
>>>
>>>> +static int veth_newlink(struct net_device *dev,
>>>> +			 struct nlattr *tb[], struct nlattr *data[])
>>>> +{
>>>> +	int err;
>>>> +	struct net_device *peer;
>>>> +	struct veth_priv *priv;
>>>> +	char ifname[IFNAMSIZ];
>>>> +
>>>> +	/*
>>>> +	 * prepare the devices info
>>>> +	 */
>>>> +
>>>> +	if (tb[IFLA_ADDRESS] == NULL)
>>>> +		random_ether_addr(dev->dev_addr);
>>>> +
>>>> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>>>> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>>>> +				data[VETH_INFO_PEER], ifla_policy);
>>>> +		if (err < 0)
>>>> +			return err;
>>>> +	}
>>>
>>> Not having a peer should be an error, no?
>>
>> No. That's the intention - if the user doesn't specify "peer" in the
>> command line then two _identical_ devices are created. Of course, if
>> he specifies one name - there'll be a collision, but one can say
>> "my_own_veth_number_%d" and everything will be ok. Or just use the 
>> default name provided. E.g. "ip link add type veth" will send a packet
>> with data[VETH_INFO_PEER} == NULL, but this is OK! User just wants a 
>> default tunnel and he will get it :)
> 
> I see.
> 
>> Does this answer your second comment below?
> 
> 
> No, to get unique names the sequence has to be:
> 
> dev_alloc_name
> register_netdevice
> dev_alloc_name
> register_netdevice
> 
> But you have:
> 
> dev_alloc_name
> dev_alloc_name (<- might allocate same name as first call)
> register_netdevice
> register_netdevice

Oops :) You're right. That's the problem. I was carried away by
testing the "peer" options and checking for names rather than
"veth%d" to work...

By the way, that will create some problems. You see, your patches
imply that the register_netdevice() will be called at the very end
of the ->newlink callback. Otherwise, the error path of any code
following the registering will have to call unregister_netdevice()
which will BUG() in free_netdev() in rtnl_newlink() - the device
state will be neither UNINITIALIZED nor UNREGISTERED :(

>>>> +static __exit void veth_exit(void)
>>>> +{
>>>> +	struct veth_priv *priv, *next;
>>>> +
>>>> +	rtnl_lock();
>>>> +	__rtnl_link_unregister(&veth_link_ops);
>>>> +
>>>> +	list_for_each_entry_safe(priv, next, &veth_list, list)
>>>> +		veth_dellink(priv->dev);
>>>> +	rtnl_unlock();
>>>
>>> Devices are unregistered automatically through the dellink function,
>>> rtnl_link_unregister(..) is enough.
>>
>> OK. This looks like a minor and not-significant comment, so
>> do I need to resend the patch or David is OK to take it and
>> I will send an incremental one?
> 
> 
> An incremental patch for this is fine I guess, your code is correct,
> its merely a simplification.
> 

Thanks,
Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> Patrick McHardy wrote:
> 
>>No, to get unique names the sequence has to be:
>>
>>dev_alloc_name
>>register_netdevice
>>dev_alloc_name
>>register_netdevice
>>
>>But you have:
>>
>>dev_alloc_name
>>dev_alloc_name (<- might allocate same name as first call)
>>register_netdevice
>>register_netdevice
> 
> 
> Oops :) You're right. That's the problem. I was carried away by
> testing the "peer" options and checking for names rather than
> "veth%d" to work...
> 
> By the way, that will create some problems. You see, your patches
> imply that the register_netdevice() will be called at the very end
> of the ->newlink callback. Otherwise, the error path of any code
> following the registering will have to call unregister_netdevice()
> which will BUG() in free_netdev() in rtnl_newlink() - the device
> state will be neither UNINITIALIZED nor UNREGISTERED :(


Thats true. I think you could do:

- use name of the supplied device for the second device
- register second device
- allocate new name for first device
- register first device

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
> +				data[VETH_INFO_PEER], ifla_policy);
> +		if (err < 0)
> +			return err;
> +	}


One more suggestion regarding the PEER attribute: you only nest
IFLA attributes below it, but some information that might be
interesting to use on device creation is contained in ifinfomsg
(flags and ifindex). So I think it would be better to use a
complete message, including header.

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> Patrick McHardy wrote:
>>
>>> No, to get unique names the sequence has to be:
>>>
>>> dev_alloc_name
>>> register_netdevice
>>> dev_alloc_name
>>> register_netdevice
>>>
>>> But you have:
>>>
>>> dev_alloc_name
>>> dev_alloc_name (<- might allocate same name as first call)
>>> register_netdevice
>>> register_netdevice
>>
>> Oops :) You're right. That's the problem. I was carried away by
>> testing the "peer" options and checking for names rather than
>> "veth%d" to work...
>>
>> By the way, that will create some problems. You see, your patches
>> imply that the register_netdevice() will be called at the very end
>> of the ->newlink callback. Otherwise, the error path of any code
>> following the registering will have to call unregister_netdevice()
>> which will BUG() in free_netdev() in rtnl_newlink() - the device
>> state will be neither UNINITIALIZED nor UNREGISTERED :(
> 
> 
> Thats true. I think you could do:
> 
> - use name of the supplied device for the second device
> - register second device
> - allocate new name for first device
> - register first device
> 

Not 100% like this (since the first name is expected to be associated
with the device with the first address), but reallocating the name for
the first device sounds like a good idea.

David, which way would be more preferable - to fix booth issues pointed
by Patric and send the v.4 patch, or to wait for this patch to be committed
and then send two incremental fixes?

Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>> +				data[VETH_INFO_PEER], ifla_policy);
>> +		if (err < 0)
>> +			return err;
>> +	}
> 
> 
> One more suggestion regarding the PEER attribute: you only nest
> IFLA attributes below it, but some information that might be
> interesting to use on device creation is contained in ifinfomsg
> (flags and ifindex). So I think it would be better to use a
> complete message, including header.

I don't get it. Can you elaborate, please.

Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> Patrick McHardy wrote:
> 
>>Pavel Emelianov wrote:
>>
>>>+	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>>>+		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>>>+				data[VETH_INFO_PEER], ifla_policy);
>>>+		if (err < 0)
>>>+			return err;
>>>+	}
>>
>>
>>One more suggestion regarding the PEER attribute: you only nest
>>IFLA attributes below it, but some information that might be
>>interesting to use on device creation is contained in ifinfomsg
>>(flags and ifindex). So I think it would be better to use a
>>complete message, including header.
> 
> 
> I don't get it. Can you elaborate, please.


You don't have a struct ifinfomsg for the peer device. At some
point we might want to add support for specifying initial flags
for the device (some easily supportable ones are IFF_PROMISC,
IFF_ALLMULTI, IFF_NOARP) and ideally that should also be possible
for the peer device.

So I suggest you use a complete ifinfomsg including the header
instead of just the attributes for VETH_INFO_PEER.

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> Patrick McHardy wrote:
>>
>>>> +
>>>> +	if (tb[IFLA_IFNAME])
>>>> +		nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
>>>> +	else
>>>> +		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
>>>
>>> Does this work? The other device is not registered at this time, so I
>>> think the allocated names could clash ..
>>
>> Oh! And one more thing, I've just thought about - even two devices with
>> similar name would be ok when we have a namespaces and one of the ends of
>> this tunnel is to be in some other namespace rather that the init one.
> 
> 
> Yes, but we don't have network namespaces yet. Which brings up another
> question: is this driver of any use without namespaces?
> 
> 

Sure. For example, you can join two bridges together.

Thanks,
Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Pavel Emelianov]

Patrick McHardy wrote:
> Pavel Emelianov wrote:
>> Patrick McHardy wrote:
>>
>>> Pavel Emelianov wrote:
>>>
>>>> +	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
>>>> +		err = nla_parse_nested(tb, IFLA_INFO_MAX,
>>>> +				data[VETH_INFO_PEER], ifla_policy);
>>>> +		if (err < 0)
>>>> +			return err;
>>>> +	}
>>>
>>> One more suggestion regarding the PEER attribute: you only nest
>>> IFLA attributes below it, but some information that might be
>>> interesting to use on device creation is contained in ifinfomsg
>>> (flags and ifindex). So I think it would be better to use a
>>> complete message, including header.
>>
>> I don't get it. Can you elaborate, please.
> 
> 
> You don't have a struct ifinfomsg for the peer device. At some
> point we might want to add support for specifying initial flags
> for the device (some easily supportable ones are IFF_PROMISC,
> IFF_ALLMULTI, IFF_NOARP) and ideally that should also be possible
> for the peer device.
> 
> So I suggest you use a complete ifinfomsg including the header
> instead of just the attributes for VETH_INFO_PEER.
> 
> 

I don't see any information from this struct being used on the
link-creation paths...

Pavel

Re: [PATCH 2/2] Virtual ethernet device driver

[Patrick McHardy]

Pavel Emelianov wrote:
> Patrick McHardy wrote:
> 
>> You don't have a struct ifinfomsg for the peer device. At some
>> point we might want to add support for specifying initial flags
>> for the device (some easily supportable ones are IFF_PROMISC,
>> IFF_ALLMULTI, IFF_NOARP) and ideally that should also be possible
>> for the peer device.
>>
>> So I suggest you use a complete ifinfomsg including the header
>> instead of just the attributes for VETH_INFO_PEER.
>>
>>
> 
> I don't see any information from this struct being used on the
> link-creation paths...


Thats what I explained twice, its not used today, it might be
used in the future for ifindex and flags.

[PATCH 2/2] Virtual ethernet device driver

[Pavel Emelyanov]

Veth stands for Virtual ETHernet. It is a simple tunnel driver
that works at the link layer and looks like a pair of ethernet
devices interconnected with each other.

Mainly it allows to communicate between network namespaces but
it can be used as is as well.

The newlink callback is organized that way to make it easy to 
create the peer device in the separate namespace when we have 
them in kernel.

This implementation uses another interface - the RTM_NRELINK
message introduced by Patric.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Patrick McHardy <kaber@trash.net>

---

 drivers/net/Kconfig  |    6 
 drivers/net/Makefile |    1 
 drivers/net/veth.c   |  475 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/net/veth.h   |   12 +
 4 files changed, 494 insertions(+)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 43d0317..ccfc002 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -134,6 +134,12 @@ config TUN
 
 	  If you don't know what to use this for, you don't need it.
 
+config VETH
+	tristate "Virtual ethernet device"
+	---help---
+	  The device is an ethernet tunnel. Devices are created in pairs. When
+	  one end receives the packet it appears on its pair and vice versa.
+
 config NET_SB1000
 	tristate "General Instruments Surfboard 1000"
 	depends on PNP
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index eb41676..32db559 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -189,6 +189,7 @@ obj-$(CONFIG_MACSONIC) += macsonic.o
 obj-$(CONFIG_MACMACE) += macmace.o
 obj-$(CONFIG_MAC89x0) += mac89x0.o
 obj-$(CONFIG_TUN) += tun.o
+obj-$(CONFIG_VETH) += veth.o
 obj-$(CONFIG_NET_NETX) += netx-eth.o
 obj-$(CONFIG_DL2K) += dl2k.o
 obj-$(CONFIG_R8169) += r8169.o
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
new file mode 100644
index 0000000..b8f33f0
--- /dev/null
+++ b/drivers/net/veth.c
@@ -0,0 +1,475 @@
+/*
+ *  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/list.h>
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/etherdevice.h>
+
+#include <net/dst.h>
+#include <net/xfrm.h>
+#include <net/veth.h>
+
+#define DRV_NAME	"veth"
+#define DRV_VERSION	"1.0"
+
+struct veth_net_stats {
+	unsigned long	rx_packets;
+	unsigned long	tx_packets;
+	unsigned long	rx_bytes;
+	unsigned long	tx_bytes;
+	unsigned long	tx_dropped;
+};
+
+struct veth_priv {
+	struct net_device *peer;
+	struct net_device *dev;
+	struct list_head list;
+	struct veth_net_stats *stats;
+	unsigned ip_summed;
+};
+
+static LIST_HEAD(veth_list);
+
+/*
+ * 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;
+	cmd->speed		= 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)
+{
+	strcpy(info->driver, DRV_NAME);
+	strcpy(info->version, DRV_VERSION);
+	strcpy(info->fw_version, "N/A");
+}
+
+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_stats_count(struct net_device *dev)
+{
+	return ARRAY_SIZE(ethtool_stats_keys);
+}
+
+static void veth_get_ethtool_stats(struct net_device *dev,
+		struct ethtool_stats *stats, u64 *data)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	data[0] = priv->peer->ifindex;
+}
+
+static u32 veth_get_rx_csum(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	return priv->ip_summed == CHECKSUM_UNNECESSARY;
+}
+
+static int veth_set_rx_csum(struct net_device *dev, u32 data)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	priv->ip_summed = data ? CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
+	return 0;
+}
+
+static u32 veth_get_tx_csum(struct net_device *dev)
+{
+	return (dev->features & NETIF_F_NO_CSUM) != 0;
+}
+
+static int veth_set_tx_csum(struct net_device *dev, u32 data)
+{
+	if (data)
+		dev->features |= NETIF_F_NO_CSUM;
+	else
+		dev->features &= ~NETIF_F_NO_CSUM;
+	return 0;
+}
+
+static struct ethtool_ops veth_ethtool_ops = {
+	.get_settings		= veth_get_settings,
+	.get_drvinfo		= veth_get_drvinfo,
+	.get_link		= ethtool_op_get_link,
+	.get_rx_csum		= veth_get_rx_csum,
+	.set_rx_csum		= veth_set_rx_csum,
+	.get_tx_csum		= veth_get_tx_csum,
+	.set_tx_csum		= veth_set_tx_csum,
+	.get_sg			= ethtool_op_get_sg,
+	.set_sg			= ethtool_op_set_sg,
+	.get_strings		= veth_get_strings,
+	.get_stats_count	= veth_get_stats_count,
+	.get_ethtool_stats	= veth_get_ethtool_stats,
+	.get_perm_addr		= ethtool_op_get_perm_addr,
+};
+
+/*
+ * xmit
+ */
+
+static int veth_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device *rcv = NULL;
+	struct veth_priv *priv, *rcv_priv;
+	struct veth_net_stats *stats;
+	int length, cpu;
+
+	skb_orphan(skb);
+
+	priv = netdev_priv(dev);
+	rcv = priv->peer;
+	rcv_priv = netdev_priv(rcv);
+
+	cpu = smp_processor_id();
+	stats = per_cpu_ptr(priv->stats, cpu);
+
+	if (!(rcv->flags & IFF_UP))
+		goto outf;
+
+	skb->pkt_type = PACKET_HOST;
+	skb->protocol = eth_type_trans(skb, rcv);
+	if (dev->features & NETIF_F_NO_CSUM)
+		skb->ip_summed = rcv_priv->ip_summed;
+
+	dst_release(skb->dst);
+	skb->dst = NULL;
+	skb->mark = 0;
+	secpath_reset(skb);
+	nf_reset(skb);
+
+	length = skb->len;
+
+	stats->tx_bytes += length;
+	stats->tx_packets++;
+
+	stats = per_cpu_ptr(rcv_priv->stats, cpu);
+	stats->rx_bytes += length;
+	stats->rx_packets++;
+
+	netif_rx(skb);
+	return 0;
+
+outf:
+	kfree_skb(skb);
+	stats->tx_dropped++;
+	return 0;
+}
+
+/*
+ * general routines
+ */
+
+static struct net_device_stats *veth_get_stats(struct net_device *dev)
+{
+	struct veth_priv *priv;
+	struct net_device_stats *dev_stats;
+	int cpu;
+	struct veth_net_stats *stats;
+	
+	priv = netdev_priv(dev);
+	dev_stats = &dev->stats;
+
+	dev_stats->rx_packets = 0;
+	dev_stats->tx_packets = 0;
+	dev_stats->rx_bytes = 0;
+	dev_stats->tx_bytes = 0;
+	dev_stats->tx_dropped = 0;
+
+	for_each_online_cpu(cpu) {
+		stats = per_cpu_ptr(priv->stats, cpu);
+
+		dev_stats->rx_packets += stats->rx_packets;
+		dev_stats->tx_packets += stats->tx_packets;
+		dev_stats->rx_bytes += stats->rx_bytes;
+		dev_stats->tx_bytes += stats->tx_bytes;
+		dev_stats->tx_dropped += stats->tx_dropped;
+	}
+
+	return dev_stats;
+}
+
+static int veth_open(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	if (priv->peer == NULL)
+		return -ENOTCONN;
+
+	if (priv->peer->flags & IFF_UP) {
+		netif_carrier_on(dev);
+		netif_carrier_on(priv->peer);
+	}
+	return 0;
+}
+
+static int veth_close(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	if (netif_carrier_ok(dev)) {
+		priv = netdev_priv(dev);
+		netif_carrier_off(dev);
+		netif_carrier_off(priv->peer);
+	}
+	return 0;
+}
+
+static int veth_dev_init(struct net_device *dev)
+{
+	struct veth_net_stats *stats;
+	struct veth_priv *priv;
+
+	stats = alloc_percpu(struct veth_net_stats);
+	if (stats == NULL)
+		return -ENOMEM;
+
+	priv = netdev_priv(dev);
+	priv->stats = stats;
+	return 0;
+}
+
+static void veth_dev_free(struct net_device *dev)
+{
+	struct veth_priv *priv;
+
+	priv = netdev_priv(dev);
+	free_percpu(priv->stats);
+	free_netdev(dev);
+}
+
+static void veth_setup(struct net_device *dev)
+{
+	ether_setup(dev);
+
+	dev->hard_start_xmit = veth_xmit;
+	dev->get_stats = veth_get_stats;
+	dev->open = veth_open;
+	dev->stop = veth_close;
+	dev->ethtool_ops = &veth_ethtool_ops;
+	dev->features |= NETIF_F_LLTX;
+	dev->init = veth_dev_init;
+	dev->destructor = veth_dev_free;
+	netif_carrier_off(dev);
+}
+
+/*
+ * 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;
+	}
+	return 0;
+}
+
+static struct rtnl_link_ops veth_link_ops;
+
+static int veth_newlink(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;
+
+	/*
+	 * create and register peer first
+	 *
+	 * struct ifinfomsg is at the head of VETH_INFO_PEER, but we
+	 * skip it since no info from it is useful yet
+	 */
+
+	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
+		struct nlattr *nla_peer;
+
+		nla_peer = data[VETH_INFO_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
+		tbp = tb;
+
+	if (tbp[IFLA_IFNAME])
+		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
+	else
+		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
+
+	peer = rtnl_create_link(ifname, &veth_link_ops, tbp);
+	if (IS_ERR(peer))
+		return PTR_ERR(peer);
+
+	if (tbp[IFLA_ADDRESS] == NULL)
+		random_ether_addr(peer->dev_addr);
+
+	err = register_netdevice(peer);
+	if (err < 0)
+		goto err_register_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)
+		random_ether_addr(dev->dev_addr);
+
+	if (tb[IFLA_IFNAME])
+		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
+	else
+		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
+
+	if (strchr(dev->name, '%')) {
+		err = dev_alloc_name(dev, dev->name);
+		if (err < 0)
+			goto err_alloc_name;
+	}
+
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto err_register_dev;
+
+	/*
+	 * tie the deviced together
+	 */
+
+	priv = netdev_priv(dev);
+	priv->dev = dev;
+	priv->peer = peer;
+	list_add(&priv->list, &veth_list);
+
+	priv = netdev_priv(peer);
+	priv->dev = peer;
+	priv->peer = dev;
+	INIT_LIST_HEAD(&priv->list);
+	return 0;
+
+err_register_dev:
+	/* nothing to do */
+err_alloc_name:
+	unregister_netdevice(peer);
+	return err;
+
+err_register_peer:
+	free_netdev(peer);
+	return err;
+}
+
+static void veth_dellink(struct net_device *dev)
+{
+	struct veth_priv *priv;
+	struct net_device *peer;
+
+	priv = netdev_priv(dev);
+	peer = priv->peer;
+
+	if (!list_empty(&priv->list))
+		list_del(&priv->list);
+
+	priv = netdev_priv(peer);
+	if (!list_empty(&priv->list))
+		list_del(&priv->list);
+
+	unregister_netdevice(dev);
+	unregister_netdevice(peer);
+}
+
+static const struct nla_policy veth_policy[VETH_INFO_MAX + 1];
+
+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)
+{
+	struct veth_priv *priv, *next;
+
+	rtnl_lock();
+	/*
+	 * cannot trust __rtnl_link_unregister() to unregister all
+	 * devices, as each ->dellink call will remove two devices
+	 * from the list at once.
+	 */
+	list_for_each_entry_safe(priv, next, &veth_list, list)
+		veth_dellink(priv->dev);
+
+	__rtnl_link_unregister(&veth_link_ops);
+	rtnl_unlock();
+}
+
+module_init(veth_init);
+module_exit(veth_exit);
+
+MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_RTNL_LINK(DRV_NAME);
diff --git a/include/net/veth.h b/include/net/veth.h
new file mode 100644
index 0000000..3354c1e
--- /dev/null
+++ b/include/net/veth.h
@@ -0,0 +1,12 @@
+#ifndef __NET_VETH_H_
+#define __NET_VETH_H_
+
+enum {
+	VETH_INFO_UNSPEC,
+	VETH_INFO_PEER,
+
+	__VETH_INFO_MAX
+#define VETH_INFO_MAX	(__VETH_INFO_MAX - 1)
+};
+
+#endif