1 files changed, 370 insertions, 0 deletions

diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
new file mode 100644
index 0000000000..f2ae03c404
--- /dev/null
+++ b/net/l2tp/l2tp_eth.c
@@ -0,0 +1,370 @@
+// 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 netdev_tx_t 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);
+
+	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 (!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) {
+		strscpy(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;
+	}
+
+	strscpy(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);