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() */
38 struct l2tp_eth {
39 struct l2tp_session *session;
40 atomic_long_t tx_bytes;
41 atomic_long_t tx_packets;
42 atomic_long_t tx_dropped;
43 atomic_long_t rx_bytes;
44 atomic_long_t rx_packets;
45 atomic_long_t rx_errors;
46 };
47
48 /* via l2tp_session_priv() */
49 struct l2tp_eth_sess {
50 struct net_device __rcu *dev;
51 };
52
l2tp_eth_dev_init(struct net_device * dev)53 static int l2tp_eth_dev_init(struct net_device *dev)
54 {
55 eth_hw_addr_random(dev);
56 eth_broadcast_addr(dev->broadcast);
57 netdev_lockdep_set_classes(dev);
58
59 return 0;
60 }
61
l2tp_eth_dev_uninit(struct net_device * dev)62 static void l2tp_eth_dev_uninit(struct net_device *dev)
63 {
64 struct l2tp_eth *priv = netdev_priv(dev);
65 struct l2tp_eth_sess *spriv;
66
67 spriv = l2tp_session_priv(priv->session);
68 RCU_INIT_POINTER(spriv->dev, NULL);
69 /* No need for synchronize_net() here. We're called by
70 * unregister_netdev*(), which does the synchronisation for us.
71 */
72 }
73
l2tp_eth_dev_xmit(struct sk_buff * skb,struct net_device * dev)74 static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
75 {
76 struct l2tp_eth *priv = netdev_priv(dev);
77 struct l2tp_session *session = priv->session;
78 unsigned int len = skb->len;
79 int ret = l2tp_xmit_skb(session, skb);
80
81 if (likely(ret == NET_XMIT_SUCCESS)) {
82 atomic_long_add(len, &priv->tx_bytes);
83 atomic_long_inc(&priv->tx_packets);
84 } else {
85 atomic_long_inc(&priv->tx_dropped);
86 }
87 return NETDEV_TX_OK;
88 }
89
l2tp_eth_get_stats64(struct net_device * dev,struct rtnl_link_stats64 * stats)90 static void l2tp_eth_get_stats64(struct net_device *dev,
91 struct rtnl_link_stats64 *stats)
92 {
93 struct l2tp_eth *priv = netdev_priv(dev);
94
95 stats->tx_bytes = (unsigned long)atomic_long_read(&priv->tx_bytes);
96 stats->tx_packets = (unsigned long)atomic_long_read(&priv->tx_packets);
97 stats->tx_dropped = (unsigned long)atomic_long_read(&priv->tx_dropped);
98 stats->rx_bytes = (unsigned long)atomic_long_read(&priv->rx_bytes);
99 stats->rx_packets = (unsigned long)atomic_long_read(&priv->rx_packets);
100 stats->rx_errors = (unsigned long)atomic_long_read(&priv->rx_errors);
101 }
102
103 static const struct net_device_ops l2tp_eth_netdev_ops = {
104 .ndo_init = l2tp_eth_dev_init,
105 .ndo_uninit = l2tp_eth_dev_uninit,
106 .ndo_start_xmit = l2tp_eth_dev_xmit,
107 .ndo_get_stats64 = l2tp_eth_get_stats64,
108 .ndo_set_mac_address = eth_mac_addr,
109 };
110
111 static struct device_type l2tpeth_type = {
112 .name = "l2tpeth",
113 };
114
l2tp_eth_dev_setup(struct net_device * dev)115 static void l2tp_eth_dev_setup(struct net_device *dev)
116 {
117 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
118 ether_setup(dev);
119 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
120 dev->features |= NETIF_F_LLTX;
121 dev->netdev_ops = &l2tp_eth_netdev_ops;
122 dev->needs_free_netdev = true;
123 }
124
l2tp_eth_dev_recv(struct l2tp_session * session,struct sk_buff * skb,int data_len)125 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
126 {
127 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
128 struct net_device *dev;
129 struct l2tp_eth *priv;
130
131 if (!pskb_may_pull(skb, ETH_HLEN))
132 goto error;
133
134 secpath_reset(skb);
135
136 /* checksums verified by L2TP */
137 skb->ip_summed = CHECKSUM_NONE;
138
139 skb_dst_drop(skb);
140 nf_reset_ct(skb);
141
142 rcu_read_lock();
143 dev = rcu_dereference(spriv->dev);
144 if (!dev)
145 goto error_rcu;
146
147 priv = netdev_priv(dev);
148 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
149 atomic_long_inc(&priv->rx_packets);
150 atomic_long_add(data_len, &priv->rx_bytes);
151 } else {
152 atomic_long_inc(&priv->rx_errors);
153 }
154 rcu_read_unlock();
155
156 return;
157
158 error_rcu:
159 rcu_read_unlock();
160 error:
161 kfree_skb(skb);
162 }
163
l2tp_eth_delete(struct l2tp_session * session)164 static void l2tp_eth_delete(struct l2tp_session *session)
165 {
166 struct l2tp_eth_sess *spriv;
167 struct net_device *dev;
168
169 if (session) {
170 spriv = l2tp_session_priv(session);
171
172 rtnl_lock();
173 dev = rtnl_dereference(spriv->dev);
174 if (dev) {
175 unregister_netdevice(dev);
176 rtnl_unlock();
177 module_put(THIS_MODULE);
178 } else {
179 rtnl_unlock();
180 }
181 }
182 }
183
l2tp_eth_show(struct seq_file * m,void * arg)184 static void l2tp_eth_show(struct seq_file *m, void *arg)
185 {
186 struct l2tp_session *session = arg;
187 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
188 struct net_device *dev;
189
190 rcu_read_lock();
191 dev = rcu_dereference(spriv->dev);
192 if (!dev) {
193 rcu_read_unlock();
194 return;
195 }
196 dev_hold(dev);
197 rcu_read_unlock();
198
199 seq_printf(m, " interface %s\n", dev->name);
200
201 dev_put(dev);
202 }
203
l2tp_eth_adjust_mtu(struct l2tp_tunnel * tunnel,struct l2tp_session * session,struct net_device * dev)204 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
205 struct l2tp_session *session,
206 struct net_device *dev)
207 {
208 unsigned int overhead = 0;
209 u32 l3_overhead = 0;
210 u32 mtu;
211
212 /* if the encap is UDP, account for UDP header size */
213 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
214 overhead += sizeof(struct udphdr);
215 dev->needed_headroom += sizeof(struct udphdr);
216 }
217
218 lock_sock(tunnel->sock);
219 l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
220 release_sock(tunnel->sock);
221
222 if (l3_overhead == 0) {
223 /* L3 Overhead couldn't be identified, this could be
224 * because tunnel->sock was NULL or the socket's
225 * address family was not IPv4 or IPv6,
226 * dev mtu stays at 1500.
227 */
228 return;
229 }
230 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
231 * UDP overhead, if any, was already factored in above.
232 */
233 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
234
235 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
236 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
237 dev->mtu = ETH_DATA_LEN - overhead;
238 else
239 dev->mtu = mtu;
240
241 dev->needed_headroom += session->hdr_len;
242 }
243
l2tp_eth_create(struct net * net,struct l2tp_tunnel * tunnel,u32 session_id,u32 peer_session_id,struct l2tp_session_cfg * cfg)244 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
245 u32 session_id, u32 peer_session_id,
246 struct l2tp_session_cfg *cfg)
247 {
248 unsigned char name_assign_type;
249 struct net_device *dev;
250 char name[IFNAMSIZ];
251 struct l2tp_session *session;
252 struct l2tp_eth *priv;
253 struct l2tp_eth_sess *spriv;
254 int rc;
255
256 if (cfg->ifname) {
257 strlcpy(name, cfg->ifname, IFNAMSIZ);
258 name_assign_type = NET_NAME_USER;
259 } else {
260 strcpy(name, L2TP_ETH_DEV_NAME);
261 name_assign_type = NET_NAME_ENUM;
262 }
263
264 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
265 peer_session_id, cfg);
266 if (IS_ERR(session)) {
267 rc = PTR_ERR(session);
268 goto err;
269 }
270
271 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
272 l2tp_eth_dev_setup);
273 if (!dev) {
274 rc = -ENOMEM;
275 goto err_sess;
276 }
277
278 dev_net_set(dev, net);
279 dev->min_mtu = 0;
280 dev->max_mtu = ETH_MAX_MTU;
281 l2tp_eth_adjust_mtu(tunnel, session, dev);
282
283 priv = netdev_priv(dev);
284 priv->session = session;
285
286 session->recv_skb = l2tp_eth_dev_recv;
287 session->session_close = l2tp_eth_delete;
288 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
289 session->show = l2tp_eth_show;
290
291 spriv = l2tp_session_priv(session);
292
293 l2tp_session_inc_refcount(session);
294
295 rtnl_lock();
296
297 /* Register both device and session while holding the rtnl lock. This
298 * ensures that l2tp_eth_delete() will see that there's a device to
299 * unregister, even if it happened to run before we assign spriv->dev.
300 */
301 rc = l2tp_session_register(session, tunnel);
302 if (rc < 0) {
303 rtnl_unlock();
304 goto err_sess_dev;
305 }
306
307 rc = register_netdevice(dev);
308 if (rc < 0) {
309 rtnl_unlock();
310 l2tp_session_delete(session);
311 l2tp_session_dec_refcount(session);
312 free_netdev(dev);
313
314 return rc;
315 }
316
317 strlcpy(session->ifname, dev->name, IFNAMSIZ);
318 rcu_assign_pointer(spriv->dev, dev);
319
320 rtnl_unlock();
321
322 l2tp_session_dec_refcount(session);
323
324 __module_get(THIS_MODULE);
325
326 return 0;
327
328 err_sess_dev:
329 l2tp_session_dec_refcount(session);
330 free_netdev(dev);
331 err_sess:
332 kfree(session);
333 err:
334 return rc;
335 }
336
337 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
338 .session_create = l2tp_eth_create,
339 .session_delete = l2tp_session_delete,
340 };
341
l2tp_eth_init(void)342 static int __init l2tp_eth_init(void)
343 {
344 int err = 0;
345
346 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
347 if (err)
348 goto err;
349
350 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
351
352 return 0;
353
354 err:
355 return err;
356 }
357
l2tp_eth_exit(void)358 static void __exit l2tp_eth_exit(void)
359 {
360 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
361 }
362
363 module_init(l2tp_eth_init);
364 module_exit(l2tp_eth_exit);
365
366 MODULE_LICENSE("GPL");
367 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
368 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
369 MODULE_VERSION("1.0");
370 MODULE_ALIAS_L2TP_PWTYPE(5);
371