1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * L2TPv3 ethernet pseudowire driver
5 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/socket.h>
13 #include <linux/hash.h>
14 #include <linux/l2tp.h>
16 #include <linux/etherdevice.h>
17 #include <linux/spinlock.h>
22 #include <net/inet_common.h>
23 #include <net/inet_hashtables.h>
24 #include <net/tcp_states.h>
25 #include <net/protocol.h>
27 #include <net/net_namespace.h>
28 #include <net/netns/generic.h>
30 #include <linux/ipv6.h>
31 #include <linux/udp.h>
33 #include "l2tp_core.h"
35 /* Default device name. May be overridden by name specified by user */
36 #define L2TP_ETH_DEV_NAME "l2tpeth%d"
38 /* via netdev_priv() */
40 struct l2tp_session *session;
41 atomic_long_t tx_bytes;
42 atomic_long_t tx_packets;
43 atomic_long_t tx_dropped;
44 atomic_long_t rx_bytes;
45 atomic_long_t rx_packets;
46 atomic_long_t rx_errors;
49 /* via l2tp_session_priv() */
50 struct l2tp_eth_sess {
51 struct net_device __rcu *dev;
55 static int l2tp_eth_dev_init(struct net_device *dev)
57 eth_hw_addr_random(dev);
58 eth_broadcast_addr(dev->broadcast);
63 static void l2tp_eth_dev_uninit(struct net_device *dev)
65 struct l2tp_eth *priv = netdev_priv(dev);
66 struct l2tp_eth_sess *spriv;
68 spriv = l2tp_session_priv(priv->session);
69 RCU_INIT_POINTER(spriv->dev, NULL);
70 /* No need for synchronize_net() here. We're called by
71 * unregister_netdev*(), which does the synchronisation for us.
75 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
77 struct l2tp_eth *priv = netdev_priv(dev);
78 struct l2tp_session *session = priv->session;
79 unsigned int len = skb->len;
80 int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
82 if (likely(ret == NET_XMIT_SUCCESS)) {
83 atomic_long_add(len, &priv->tx_bytes);
84 atomic_long_inc(&priv->tx_packets);
86 atomic_long_inc(&priv->tx_dropped);
91 static void l2tp_eth_get_stats64(struct net_device *dev,
92 struct rtnl_link_stats64 *stats)
94 struct l2tp_eth *priv = netdev_priv(dev);
96 stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes);
97 stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
98 stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
99 stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes);
100 stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
101 stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors);
105 static const struct net_device_ops l2tp_eth_netdev_ops = {
106 .ndo_init = l2tp_eth_dev_init,
107 .ndo_uninit = l2tp_eth_dev_uninit,
108 .ndo_start_xmit = l2tp_eth_dev_xmit,
109 .ndo_get_stats64 = l2tp_eth_get_stats64,
110 .ndo_set_mac_address = eth_mac_addr,
113 static struct device_type l2tpeth_type = {
117 static void l2tp_eth_dev_setup(struct net_device *dev)
119 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
121 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
122 dev->features |= NETIF_F_LLTX;
123 dev->netdev_ops = &l2tp_eth_netdev_ops;
124 dev->needs_free_netdev = true;
127 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
129 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
130 struct net_device *dev;
131 struct l2tp_eth *priv;
133 if (session->debug & L2TP_MSG_DATA) {
136 length = min(32u, skb->len);
137 if (!pskb_may_pull(skb, length))
140 pr_debug("%s: eth recv\n", session->name);
141 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
144 if (!pskb_may_pull(skb, ETH_HLEN))
149 /* checksums verified by L2TP */
150 skb->ip_summed = CHECKSUM_NONE;
156 dev = rcu_dereference(spriv->dev);
160 priv = netdev_priv(dev);
161 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
162 atomic_long_inc(&priv->rx_packets);
163 atomic_long_add(data_len, &priv->rx_bytes);
165 atomic_long_inc(&priv->rx_errors);
177 static void l2tp_eth_delete(struct l2tp_session *session)
179 struct l2tp_eth_sess *spriv;
180 struct net_device *dev;
183 spriv = l2tp_session_priv(session);
186 dev = rtnl_dereference(spriv->dev);
188 unregister_netdevice(dev);
190 module_put(THIS_MODULE);
197 static void l2tp_eth_show(struct seq_file *m, void *arg)
199 struct l2tp_session *session = arg;
200 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
201 struct net_device *dev;
204 dev = rcu_dereference(spriv->dev);
212 seq_printf(m, " interface %s\n", dev->name);
217 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
218 struct l2tp_session *session,
219 struct net_device *dev)
221 unsigned int overhead = 0;
225 /* if the encap is UDP, account for UDP header size */
226 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
227 overhead += sizeof(struct udphdr);
228 dev->needed_headroom += sizeof(struct udphdr);
231 lock_sock(tunnel->sock);
232 l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
233 release_sock(tunnel->sock);
235 if (l3_overhead == 0) {
236 /* L3 Overhead couldn't be identified, this could be
237 * because tunnel->sock was NULL or the socket's
238 * address family was not IPv4 or IPv6,
239 * dev mtu stays at 1500.
243 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
244 * UDP overhead, if any, was already factored in above.
246 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
248 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
249 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
250 dev->mtu = ETH_DATA_LEN - overhead;
254 dev->needed_headroom += session->hdr_len;
257 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
258 u32 session_id, u32 peer_session_id,
259 struct l2tp_session_cfg *cfg)
261 unsigned char name_assign_type;
262 struct net_device *dev;
264 struct l2tp_session *session;
265 struct l2tp_eth *priv;
266 struct l2tp_eth_sess *spriv;
270 strlcpy(name, cfg->ifname, IFNAMSIZ);
271 name_assign_type = NET_NAME_USER;
273 strcpy(name, L2TP_ETH_DEV_NAME);
274 name_assign_type = NET_NAME_ENUM;
277 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
278 peer_session_id, cfg);
279 if (IS_ERR(session)) {
280 rc = PTR_ERR(session);
284 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
291 dev_net_set(dev, net);
293 dev->max_mtu = ETH_MAX_MTU;
294 l2tp_eth_adjust_mtu(tunnel, session, dev);
296 priv = netdev_priv(dev);
297 priv->session = session;
299 session->recv_skb = l2tp_eth_dev_recv;
300 session->session_close = l2tp_eth_delete;
301 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
302 session->show = l2tp_eth_show;
304 spriv = l2tp_session_priv(session);
306 l2tp_session_inc_refcount(session);
310 /* Register both device and session while holding the rtnl lock. This
311 * ensures that l2tp_eth_delete() will see that there's a device to
312 * unregister, even if it happened to run before we assign spriv->dev.
314 rc = l2tp_session_register(session, tunnel);
320 rc = register_netdevice(dev);
323 l2tp_session_delete(session);
324 l2tp_session_dec_refcount(session);
330 strlcpy(session->ifname, dev->name, IFNAMSIZ);
331 rcu_assign_pointer(spriv->dev, dev);
335 l2tp_session_dec_refcount(session);
337 __module_get(THIS_MODULE);
342 l2tp_session_dec_refcount(session);
351 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
352 .session_create = l2tp_eth_create,
353 .session_delete = l2tp_session_delete,
357 static int __init l2tp_eth_init(void)
361 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
365 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
373 static void __exit l2tp_eth_exit(void)
375 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
378 module_init(l2tp_eth_init);
379 module_exit(l2tp_eth_exit);
381 MODULE_LICENSE("GPL");
382 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
383 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
384 MODULE_VERSION("1.0");
385 MODULE_ALIAS_L2TP_PWTYPE(5);