net/l2tp/l2tp_eth.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * L2TPv3 ethernet pseudowire driver
  *
  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/socket.h>
 #include <linux/hash.h>
 #include <linux/l2tp.h>
 #include <linux/in.h>
 #include <linux/etherdevice.h>
 #include <linux/spinlock.h>
 #include <net/sock.h>
 #include <net/ip.h>
 #include <net/icmp.h>
 #include <net/udp.h>
 #include <net/inet_common.h>
 #include <net/inet_hashtables.h>
 #include <net/tcp_states.h>
 #include <net/protocol.h>
 #include <net/xfrm.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/udp.h>

 #include "l2tp_core.h"

 /* Default device name. May be overridden by name specified by user */
 #define L2TP_ETH_DEV_NAME	"l2tpeth%d"

 /* via netdev_priv() */
 struct l2tp_eth {
 	struct l2tp_session	*session;
 	atomic_long_t		tx_bytes;
 	atomic_long_t		tx_packets;
 	atomic_long_t		tx_dropped;
 	atomic_long_t		rx_bytes;
 	atomic_long_t		rx_packets;
 	atomic_long_t		rx_errors;
 };

 /* via l2tp_session_priv() */
 struct l2tp_eth_sess {
 	struct net_device __rcu *dev;
 };


 static int l2tp_eth_dev_init(struct net_device *dev)
 {
 	eth_hw_addr_random(dev);
 	eth_broadcast_addr(dev->broadcast);
 	netdev_lockdep_set_classes(dev);

 	return 0;
 }

 static void l2tp_eth_dev_uninit(struct net_device *dev)
 {
 	struct l2tp_eth *priv = netdev_priv(dev);
 	struct l2tp_eth_sess *spriv;

 	spriv = l2tp_session_priv(priv->session);
 	RCU_INIT_POINTER(spriv->dev, NULL);
 	/* No need for synchronize_net() here. We're called by
 	 * unregister_netdev*(), which does the synchronisation for us.
 	 */
 }

 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct l2tp_eth *priv = netdev_priv(dev);
 	struct l2tp_session *session = priv->session;
 	unsigned int len = skb->len;
 	int ret = l2tp_xmit_skb(session, skb, session->hdr_len);

 	if (likely(ret == NET_XMIT_SUCCESS)) {
 		atomic_long_add(len, &priv->tx_bytes);
 		atomic_long_inc(&priv->tx_packets);
 	} else {
 		atomic_long_inc(&priv->tx_dropped);
 	}
 	return NETDEV_TX_OK;
 }

 static void l2tp_eth_get_stats64(struct net_device *dev,
 				 struct rtnl_link_stats64 *stats)
 {
 	struct l2tp_eth *priv = netdev_priv(dev);

 	stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
 	stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
 	stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
 	stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
 	stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
 	stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);

 }

 static const struct net_device_ops l2tp_eth_netdev_ops = {
 	.ndo_init		= l2tp_eth_dev_init,
 	.ndo_uninit		= l2tp_eth_dev_uninit,
 	.ndo_start_xmit		= l2tp_eth_dev_xmit,
 	.ndo_get_stats64	= l2tp_eth_get_stats64,
 	.ndo_set_mac_address	= eth_mac_addr,
 };

 static struct device_type l2tpeth_type = {
 	.name = "l2tpeth",
 };

 static void l2tp_eth_dev_setup(struct net_device *dev)
 {
 	SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 	ether_setup(dev);
 	dev->priv_flags		&= ~IFF_TX_SKB_SHARING;
 	dev->features		|= NETIF_F_LLTX;
 	dev->netdev_ops		= &l2tp_eth_netdev_ops;
 	dev->needs_free_netdev	= true;
 }

 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 {
 	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 	struct net_device *dev;
 	struct l2tp_eth *priv;

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

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

 		pr_debug("%s: eth recv\n", session->name);
 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 	}

 	if (!pskb_may_pull(skb, ETH_HLEN))
 		goto error;

 	secpath_reset(skb);

 	/* checksums verified by L2TP */
 	skb->ip_summed = CHECKSUM_NONE;

 	skb_dst_drop(skb);
 	nf_reset_ct(skb);

 	rcu_read_lock();
 	dev = rcu_dereference(spriv->dev);
 	if (!dev)
 		goto error_rcu;

 	priv = netdev_priv(dev);
 	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 		atomic_long_inc(&priv->rx_packets);
 		atomic_long_add(data_len, &priv->rx_bytes);
 	} else {
 		atomic_long_inc(&priv->rx_errors);
 	}
 	rcu_read_unlock();

 	return;

 error_rcu:
 	rcu_read_unlock();
 error:
 	kfree_skb(skb);
 }

 static void l2tp_eth_delete(struct l2tp_session *session)
 {
 	struct l2tp_eth_sess *spriv;
 	struct net_device *dev;

 	if (session) {
 		spriv = l2tp_session_priv(session);

 		rtnl_lock();
 		dev = rtnl_dereference(spriv->dev);
 		if (dev) {
 			unregister_netdevice(dev);
 			rtnl_unlock();
 			module_put(THIS_MODULE);
 		} else {
 			rtnl_unlock();
 		}
 	}
 }

 static void l2tp_eth_show(struct seq_file *m, void *arg)
 {
 	struct l2tp_session *session = arg;
 	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 	struct net_device *dev;

 	rcu_read_lock();
 	dev = rcu_dereference(spriv->dev);
 	if (!dev) {
 		rcu_read_unlock();
 		return;
 	}
 	dev_hold(dev);
 	rcu_read_unlock();

 	seq_printf(m, "   interface %s\n", dev->name);

 	dev_put(dev);
 }

 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 				struct l2tp_session *session,
 				struct net_device *dev)
 {
 	unsigned int overhead = 0;
 	u32 l3_overhead = 0;
 	u32 mtu;

 	/* if the encap is UDP, account for UDP header size */
 	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 		overhead += sizeof(struct udphdr);
 		dev->needed_headroom += sizeof(struct udphdr);
 	}

 	lock_sock(tunnel->sock);
 	l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
 	release_sock(tunnel->sock);

 	if (l3_overhead == 0) {
 		/* L3 Overhead couldn't be identified, this could be
 		 * because tunnel->sock was NULL or the socket's
 		 * address family was not IPv4 or IPv6,
 		 * dev mtu stays at 1500.
 		 */
 		return;
 	}
 	/* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
 	 * UDP overhead, if any, was already factored in above.
 	 */
 	overhead += session->hdr_len + ETH_HLEN + l3_overhead;

 	mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
 	if (mtu < dev->min_mtu || mtu > dev->max_mtu)
 		dev->mtu = ETH_DATA_LEN - overhead;
 	else
 		dev->mtu = mtu;

 	dev->needed_headroom += session->hdr_len;
 }

 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 			   u32 session_id, u32 peer_session_id,
 			   struct l2tp_session_cfg *cfg)
 {
 	unsigned char name_assign_type;
 	struct net_device *dev;
 	char name[IFNAMSIZ];
 	struct l2tp_session *session;
 	struct l2tp_eth *priv;
 	struct l2tp_eth_sess *spriv;
 	int rc;

 	if (cfg->ifname) {
 		strlcpy(name, cfg->ifname, IFNAMSIZ);
 		name_assign_type = NET_NAME_USER;
 	} else {
 		strcpy(name, L2TP_ETH_DEV_NAME);
 		name_assign_type = NET_NAME_ENUM;
 	}

 	session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 				      peer_session_id, cfg);
 	if (IS_ERR(session)) {
 		rc = PTR_ERR(session);
 		goto err;
 	}

 	dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
 			   l2tp_eth_dev_setup);
 	if (!dev) {
 		rc = -ENOMEM;
 		goto err_sess;
 	}

 	dev_net_set(dev, net);
 	dev->min_mtu = 0;
 	dev->max_mtu = ETH_MAX_MTU;
 	l2tp_eth_adjust_mtu(tunnel, session, dev);

 	priv = netdev_priv(dev);
 	priv->session = session;

 	session->recv_skb = l2tp_eth_dev_recv;
 	session->session_close = l2tp_eth_delete;
 	if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
 		session->show = l2tp_eth_show;

 	spriv = l2tp_session_priv(session);

 	l2tp_session_inc_refcount(session);

 	rtnl_lock();

 	/* Register both device and session while holding the rtnl lock. This
 	 * ensures that l2tp_eth_delete() will see that there's a device to
 	 * unregister, even if it happened to run before we assign spriv->dev.
 	 */
 	rc = l2tp_session_register(session, tunnel);
 	if (rc < 0) {
 		rtnl_unlock();
 		goto err_sess_dev;
 	}

 	rc = register_netdevice(dev);
 	if (rc < 0) {
 		rtnl_unlock();
 		l2tp_session_delete(session);
 		l2tp_session_dec_refcount(session);
 		free_netdev(dev);

 		return rc;
 	}

 	strlcpy(session->ifname, dev->name, IFNAMSIZ);
 	rcu_assign_pointer(spriv->dev, dev);

 	rtnl_unlock();

 	l2tp_session_dec_refcount(session);

 	__module_get(THIS_MODULE);

 	return 0;

 err_sess_dev:
 	l2tp_session_dec_refcount(session);
 	free_netdev(dev);
 err_sess:
 	kfree(session);
 err:
 	return rc;
 }


 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 	.session_create	= l2tp_eth_create,
 	.session_delete	= l2tp_session_delete,
 };


 static int __init l2tp_eth_init(void)
 {
 	int err = 0;

 	err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 	if (err)
 		goto err;

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

 	return 0;

 err:
 	return err;
 }

 static void __exit l2tp_eth_exit(void)
 {
 	l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 }

 module_init(l2tp_eth_init);
 module_exit(l2tp_eth_exit);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 MODULE_VERSION("1.0");
 MODULE_ALIAS_L2TP_PWTYPE(5);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* L2TPv3 ethernet pseudowire driver
	*
	* Copyright (c) 2008,2009,2010 Katalix Systems Ltd
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <linux/socket.h>
	#include <linux/hash.h>
	#include <linux/l2tp.h>
	#include <linux/in.h>
	#include <linux/etherdevice.h>
	#include <linux/spinlock.h>
	#include <net/sock.h>
	#include <net/ip.h>
	#include <net/icmp.h>
	#include <net/udp.h>
	#include <net/inet_common.h>
	#include <net/inet_hashtables.h>
	#include <net/tcp_states.h>
	#include <net/protocol.h>
	#include <net/xfrm.h>
	#include <net/net_namespace.h>
	#include <net/netns/generic.h>
	#include <linux/ip.h>
	#include <linux/ipv6.h>
	#include <linux/udp.h>

	#include "l2tp_core.h"

	/* Default device name. May be overridden by name specified by user */
	#define L2TP_ETH_DEV_NAME "l2tpeth%d"

	/* via netdev_priv() */
	struct l2tp_eth {
	struct l2tp_session *session;
	atomic_long_t tx_bytes;
	atomic_long_t tx_packets;
	atomic_long_t tx_dropped;
	atomic_long_t rx_bytes;
	atomic_long_t rx_packets;
	atomic_long_t rx_errors;
	};

	/* via l2tp_session_priv() */
	struct l2tp_eth_sess {
	struct net_device __rcu *dev;
	};


	static int l2tp_eth_dev_init(struct net_device *dev)
	{
	eth_hw_addr_random(dev);
	eth_broadcast_addr(dev->broadcast);
	netdev_lockdep_set_classes(dev);

	return 0;
	}

	static void l2tp_eth_dev_uninit(struct net_device *dev)
	{
	struct l2tp_eth *priv = netdev_priv(dev);
	struct l2tp_eth_sess *spriv;

	spriv = l2tp_session_priv(priv->session);
	RCU_INIT_POINTER(spriv->dev, NULL);
	/* No need for synchronize_net() here. We're called by
	* unregister_netdev*(), which does the synchronisation for us.
	*/
	}

	static int l2tp_eth_dev_xmit(struct sk_buff skb, struct net_device dev)
	{
	struct l2tp_eth *priv = netdev_priv(dev);
	struct l2tp_session *session = priv->session;
	unsigned int len = skb->len;
	int ret = l2tp_xmit_skb(session, skb, session->hdr_len);

	if (likely(ret == NET_XMIT_SUCCESS)) {
	atomic_long_add(len, &priv->tx_bytes);
	atomic_long_inc(&priv->tx_packets);
	} else {
	atomic_long_inc(&priv->tx_dropped);
	}
	return NETDEV_TX_OK;
	}

	static void l2tp_eth_get_stats64(struct net_device *dev,
	struct rtnl_link_stats64 *stats)
	{
	struct l2tp_eth *priv = netdev_priv(dev);

	stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
	stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
	stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
	stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
	stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
	stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);

	}

	static const struct net_device_ops l2tp_eth_netdev_ops = {
	.ndo_init = l2tp_eth_dev_init,
	.ndo_uninit = l2tp_eth_dev_uninit,
	.ndo_start_xmit = l2tp_eth_dev_xmit,
	.ndo_get_stats64 = l2tp_eth_get_stats64,
	.ndo_set_mac_address = eth_mac_addr,
	};

	static struct device_type l2tpeth_type = {
	.name = "l2tpeth",
	};

	static void l2tp_eth_dev_setup(struct net_device *dev)
	{
	SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
	ether_setup(dev);
	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
	dev->features \|= NETIF_F_LLTX;
	dev->netdev_ops = &l2tp_eth_netdev_ops;
	dev->needs_free_netdev = true;
	}

	static void l2tp_eth_dev_recv(struct l2tp_session session, struct sk_buff skb, int data_len)
	{
	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
	struct net_device *dev;
	struct l2tp_eth *priv;

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

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

	pr_debug("%s: eth recv\n", session->name);
	print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
	}

	if (!pskb_may_pull(skb, ETH_HLEN))
	goto error;

	secpath_reset(skb);

	/* checksums verified by L2TP */
	skb->ip_summed = CHECKSUM_NONE;

	skb_dst_drop(skb);
	nf_reset_ct(skb);

	rcu_read_lock();
	dev = rcu_dereference(spriv->dev);
	if (!dev)
	goto error_rcu;

	priv = netdev_priv(dev);
	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
	atomic_long_inc(&priv->rx_packets);
	atomic_long_add(data_len, &priv->rx_bytes);
	} else {
	atomic_long_inc(&priv->rx_errors);
	}
	rcu_read_unlock();

	return;

	error_rcu:
	rcu_read_unlock();
	error:
	kfree_skb(skb);
	}

	static void l2tp_eth_delete(struct l2tp_session *session)
	{
	struct l2tp_eth_sess *spriv;
	struct net_device *dev;

	if (session) {
	spriv = l2tp_session_priv(session);

	rtnl_lock();
	dev = rtnl_dereference(spriv->dev);
	if (dev) {
	unregister_netdevice(dev);
	rtnl_unlock();
	module_put(THIS_MODULE);
	} else {
	rtnl_unlock();
	}
	}
	}

	static void l2tp_eth_show(struct seq_file m, void arg)
	{
	struct l2tp_session *session = arg;
	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
	struct net_device *dev;

	rcu_read_lock();
	dev = rcu_dereference(spriv->dev);
	if (!dev) {
	rcu_read_unlock();
	return;
	}
	dev_hold(dev);
	rcu_read_unlock();

	seq_printf(m, " interface %s\n", dev->name);

	dev_put(dev);
	}

	static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
	struct l2tp_session *session,
	struct net_device *dev)
	{
	unsigned int overhead = 0;
	u32 l3_overhead = 0;
	u32 mtu;

	/* if the encap is UDP, account for UDP header size */
	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
	overhead += sizeof(struct udphdr);
	dev->needed_headroom += sizeof(struct udphdr);
	}

	lock_sock(tunnel->sock);
	l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
	release_sock(tunnel->sock);

	if (l3_overhead == 0) {
	/* L3 Overhead couldn't be identified, this could be
	* because tunnel->sock was NULL or the socket's
	* address family was not IPv4 or IPv6,
	* dev mtu stays at 1500.
	*/
	return;
	}
	/* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
	* UDP overhead, if any, was already factored in above.
	*/
	overhead += session->hdr_len + ETH_HLEN + l3_overhead;

	mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
	if (mtu < dev->min_mtu \|\| mtu > dev->max_mtu)
	dev->mtu = ETH_DATA_LEN - overhead;
	else
	dev->mtu = mtu;

	dev->needed_headroom += session->hdr_len;
	}

	static int l2tp_eth_create(struct net net, struct l2tp_tunnel tunnel,
	u32 session_id, u32 peer_session_id,
	struct l2tp_session_cfg *cfg)
	{
	unsigned char name_assign_type;
	struct net_device *dev;
	char name[IFNAMSIZ];
	struct l2tp_session *session;
	struct l2tp_eth *priv;
	struct l2tp_eth_sess *spriv;
	int rc;

	if (cfg->ifname) {
	strlcpy(name, cfg->ifname, IFNAMSIZ);
	name_assign_type = NET_NAME_USER;
	} else {
	strcpy(name, L2TP_ETH_DEV_NAME);
	name_assign_type = NET_NAME_ENUM;
	}

	session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
	peer_session_id, cfg);
	if (IS_ERR(session)) {
	rc = PTR_ERR(session);
	goto err;
	}

	dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
	l2tp_eth_dev_setup);
	if (!dev) {
	rc = -ENOMEM;
	goto err_sess;
	}

	dev_net_set(dev, net);
	dev->min_mtu = 0;
	dev->max_mtu = ETH_MAX_MTU;
	l2tp_eth_adjust_mtu(tunnel, session, dev);

	priv = netdev_priv(dev);
	priv->session = session;

	session->recv_skb = l2tp_eth_dev_recv;
	session->session_close = l2tp_eth_delete;
	if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
	session->show = l2tp_eth_show;

	spriv = l2tp_session_priv(session);

	l2tp_session_inc_refcount(session);

	rtnl_lock();

	/* Register both device and session while holding the rtnl lock. This
	* ensures that l2tp_eth_delete() will see that there's a device to
	* unregister, even if it happened to run before we assign spriv->dev.
	*/
	rc = l2tp_session_register(session, tunnel);
	if (rc < 0) {
	rtnl_unlock();
	goto err_sess_dev;
	}

	rc = register_netdevice(dev);
	if (rc < 0) {
	rtnl_unlock();
	l2tp_session_delete(session);
	l2tp_session_dec_refcount(session);
	free_netdev(dev);

	return rc;
	}

	strlcpy(session->ifname, dev->name, IFNAMSIZ);
	rcu_assign_pointer(spriv->dev, dev);

	rtnl_unlock();

	l2tp_session_dec_refcount(session);

	__module_get(THIS_MODULE);

	return 0;

	err_sess_dev:
	l2tp_session_dec_refcount(session);
	free_netdev(dev);
	err_sess:
	kfree(session);
	err:
	return rc;
	}


	static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
	.session_create = l2tp_eth_create,
	.session_delete = l2tp_session_delete,
	};


	static int __init l2tp_eth_init(void)
	{
	int err = 0;

	err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
	if (err)
	goto err;

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

	return 0;

	err:
	return err;
	}

	static void __exit l2tp_eth_exit(void)
	{
	l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
	}

	module_init(l2tp_eth_init);
	module_exit(l2tp_eth_exit);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
	MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
	MODULE_VERSION("1.0");
	MODULE_ALIAS_L2TP_PWTYPE(5);