1// SPDX-License-Identifier: GPL-2.0-or-later
2/* L2TPv3 ethernet pseudowire driver
3 *
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/socket.h>
12#include <linux/hash.h>
13#include <linux/l2tp.h>
14#include <linux/in.h>
15#include <linux/etherdevice.h>
16#include <linux/spinlock.h>
17#include <net/sock.h>
18#include <net/ip.h>
19#include <net/icmp.h>
20#include <net/udp.h>
21#include <net/inet_common.h>
22#include <net/inet_hashtables.h>
23#include <net/tcp_states.h>
24#include <net/protocol.h>
25#include <net/xfrm.h>
26#include <net/net_namespace.h>
27#include <net/netns/generic.h>
28#include <linux/ip.h>
29#include <linux/ipv6.h>
30#include <linux/udp.h>
31
32#include "l2tp_core.h"
33
34/* Default device name. May be overridden by name specified by user */
35#define L2TP_ETH_DEV_NAME "l2tpeth%d"
36
37/* via netdev_priv() */
38struct l2tp_eth {
39 struct l2tp_session *session;
40};
41
42/* via l2tp_session_priv() */
43struct l2tp_eth_sess {
44 struct net_device __rcu *dev;
45};
46
47static int l2tp_eth_dev_init(struct net_device *dev)
48{
49 eth_hw_addr_random(dev);
50 eth_broadcast_addr(addr: dev->broadcast);
51 netdev_lockdep_set_classes(dev);
52
53 return 0;
54}
55
56static void l2tp_eth_dev_uninit(struct net_device *dev)
57{
58 struct l2tp_eth *priv = netdev_priv(dev);
59 struct l2tp_eth_sess *spriv;
60
61 spriv = l2tp_session_priv(session: priv->session);
62 RCU_INIT_POINTER(spriv->dev, NULL);
63 /* No need for synchronize_net() here. We're called by
64 * unregister_netdev*(), which does the synchronisation for us.
65 */
66}
67
68static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
69{
70 struct l2tp_eth *priv = netdev_priv(dev);
71 struct l2tp_session *session = priv->session;
72 unsigned int len = skb->len;
73 int ret = l2tp_xmit_skb(session, skb);
74
75 if (likely(ret == NET_XMIT_SUCCESS)) {
76 DEV_STATS_ADD(dev, tx_bytes, len);
77 DEV_STATS_INC(dev, tx_packets);
78 } else {
79 DEV_STATS_INC(dev, tx_dropped);
80 }
81 return NETDEV_TX_OK;
82}
83
84static void l2tp_eth_get_stats64(struct net_device *dev,
85 struct rtnl_link_stats64 *stats)
86{
87 stats->tx_bytes = DEV_STATS_READ(dev, tx_bytes);
88 stats->tx_packets = DEV_STATS_READ(dev, tx_packets);
89 stats->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
90 stats->rx_bytes = DEV_STATS_READ(dev, rx_bytes);
91 stats->rx_packets = DEV_STATS_READ(dev, rx_packets);
92 stats->rx_errors = DEV_STATS_READ(dev, rx_errors);
93}
94
95static const struct net_device_ops l2tp_eth_netdev_ops = {
96 .ndo_init = l2tp_eth_dev_init,
97 .ndo_uninit = l2tp_eth_dev_uninit,
98 .ndo_start_xmit = l2tp_eth_dev_xmit,
99 .ndo_get_stats64 = l2tp_eth_get_stats64,
100 .ndo_set_mac_address = eth_mac_addr,
101};
102
103static struct device_type l2tpeth_type = {
104 .name = "l2tpeth",
105};
106
107static void l2tp_eth_dev_setup(struct net_device *dev)
108{
109 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
110 ether_setup(dev);
111 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
112 dev->features |= NETIF_F_LLTX;
113 dev->netdev_ops = &l2tp_eth_netdev_ops;
114 dev->needs_free_netdev = true;
115}
116
117static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
118{
119 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
120 struct net_device *dev;
121
122 if (!pskb_may_pull(skb, ETH_HLEN))
123 goto error;
124
125 secpath_reset(skb);
126
127 /* checksums verified by L2TP */
128 skb->ip_summed = CHECKSUM_NONE;
129
130 skb_dst_drop(skb);
131 nf_reset_ct(skb);
132
133 rcu_read_lock();
134 dev = rcu_dereference(spriv->dev);
135 if (!dev)
136 goto error_rcu;
137
138 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
139 DEV_STATS_INC(dev, rx_packets);
140 DEV_STATS_ADD(dev, rx_bytes, data_len);
141 } else {
142 DEV_STATS_INC(dev, rx_errors);
143 }
144 rcu_read_unlock();
145
146 return;
147
148error_rcu:
149 rcu_read_unlock();
150error:
151 kfree_skb(skb);
152}
153
154static void l2tp_eth_delete(struct l2tp_session *session)
155{
156 struct l2tp_eth_sess *spriv;
157 struct net_device *dev;
158
159 if (session) {
160 spriv = l2tp_session_priv(session);
161
162 rtnl_lock();
163 dev = rtnl_dereference(spriv->dev);
164 if (dev) {
165 unregister_netdevice(dev);
166 rtnl_unlock();
167 module_put(THIS_MODULE);
168 } else {
169 rtnl_unlock();
170 }
171 }
172}
173
174static void l2tp_eth_show(struct seq_file *m, void *arg)
175{
176 struct l2tp_session *session = arg;
177 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
178 struct net_device *dev;
179
180 rcu_read_lock();
181 dev = rcu_dereference(spriv->dev);
182 if (!dev) {
183 rcu_read_unlock();
184 return;
185 }
186 dev_hold(dev);
187 rcu_read_unlock();
188
189 seq_printf(m, fmt: " interface %s\n", dev->name);
190
191 dev_put(dev);
192}
193
194static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
195 struct l2tp_session *session,
196 struct net_device *dev)
197{
198 unsigned int overhead = 0;
199 u32 l3_overhead = 0;
200 u32 mtu;
201
202 /* if the encap is UDP, account for UDP header size */
203 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
204 overhead += sizeof(struct udphdr);
205 dev->needed_headroom += sizeof(struct udphdr);
206 }
207
208 lock_sock(sk: tunnel->sock);
209 l3_overhead = kernel_sock_ip_overhead(sk: tunnel->sock);
210 release_sock(sk: tunnel->sock);
211
212 if (l3_overhead == 0) {
213 /* L3 Overhead couldn't be identified, this could be
214 * because tunnel->sock was NULL or the socket's
215 * address family was not IPv4 or IPv6,
216 * dev mtu stays at 1500.
217 */
218 return;
219 }
220 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
221 * UDP overhead, if any, was already factored in above.
222 */
223 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
224
225 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
226 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
227 dev->mtu = ETH_DATA_LEN - overhead;
228 else
229 dev->mtu = mtu;
230
231 dev->needed_headroom += session->hdr_len;
232}
233
234static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
235 u32 session_id, u32 peer_session_id,
236 struct l2tp_session_cfg *cfg)
237{
238 unsigned char name_assign_type;
239 struct net_device *dev;
240 char name[IFNAMSIZ];
241 struct l2tp_session *session;
242 struct l2tp_eth *priv;
243 struct l2tp_eth_sess *spriv;
244 int rc;
245
246 if (cfg->ifname) {
247 strscpy(p: name, q: cfg->ifname, IFNAMSIZ);
248 name_assign_type = NET_NAME_USER;
249 } else {
250 strcpy(p: name, L2TP_ETH_DEV_NAME);
251 name_assign_type = NET_NAME_ENUM;
252 }
253
254 session = l2tp_session_create(priv_size: sizeof(*spriv), tunnel, session_id,
255 peer_session_id, cfg);
256 if (IS_ERR(ptr: session)) {
257 rc = PTR_ERR(ptr: session);
258 goto err;
259 }
260
261 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
262 l2tp_eth_dev_setup);
263 if (!dev) {
264 rc = -ENOMEM;
265 goto err_sess;
266 }
267
268 dev_net_set(dev, net);
269 dev->min_mtu = 0;
270 dev->max_mtu = ETH_MAX_MTU;
271 l2tp_eth_adjust_mtu(tunnel, session, dev);
272
273 priv = netdev_priv(dev);
274 priv->session = session;
275
276 session->recv_skb = l2tp_eth_dev_recv;
277 session->session_close = l2tp_eth_delete;
278 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
279 session->show = l2tp_eth_show;
280
281 spriv = l2tp_session_priv(session);
282
283 l2tp_session_inc_refcount(session);
284
285 rtnl_lock();
286
287 /* Register both device and session while holding the rtnl lock. This
288 * ensures that l2tp_eth_delete() will see that there's a device to
289 * unregister, even if it happened to run before we assign spriv->dev.
290 */
291 rc = l2tp_session_register(session, tunnel);
292 if (rc < 0) {
293 rtnl_unlock();
294 goto err_sess_dev;
295 }
296
297 rc = register_netdevice(dev);
298 if (rc < 0) {
299 rtnl_unlock();
300 l2tp_session_delete(session);
301 l2tp_session_dec_refcount(session);
302 free_netdev(dev);
303
304 return rc;
305 }
306
307 strscpy(p: session->ifname, q: dev->name, IFNAMSIZ);
308 rcu_assign_pointer(spriv->dev, dev);
309
310 rtnl_unlock();
311
312 l2tp_session_dec_refcount(session);
313
314 __module_get(THIS_MODULE);
315
316 return 0;
317
318err_sess_dev:
319 l2tp_session_dec_refcount(session);
320 free_netdev(dev);
321err_sess:
322 kfree(objp: session);
323err:
324 return rc;
325}
326
327static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
328 .session_create = l2tp_eth_create,
329 .session_delete = l2tp_session_delete,
330};
331
332static int __init l2tp_eth_init(void)
333{
334 int err = 0;
335
336 err = l2tp_nl_register_ops(pw_type: L2TP_PWTYPE_ETH, ops: &l2tp_eth_nl_cmd_ops);
337 if (err)
338 goto err;
339
340 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
341
342 return 0;
343
344err:
345 return err;
346}
347
348static void __exit l2tp_eth_exit(void)
349{
350 l2tp_nl_unregister_ops(pw_type: L2TP_PWTYPE_ETH);
351}
352
353module_init(l2tp_eth_init);
354module_exit(l2tp_eth_exit);
355
356MODULE_LICENSE("GPL");
357MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
358MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
359MODULE_VERSION("1.0");
360MODULE_ALIAS_L2TP_PWTYPE(5);
361

source code of linux/net/l2tp/l2tp_eth.c