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 };
41
42 /* via l2tp_session_priv() */
43 struct l2tp_eth_sess {
44 struct net_device __rcu *dev;
45 };
46
47 static int l2tp_eth_dev_init(struct net_device *dev)
48 {
49 eth_hw_addr_random(dev);
50 eth_broadcast_addr(dev->broadcast);
51 netdev_lockdep_set_classes(dev);
52
53 return 0;
54 }
55
56 static 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(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
68 static 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
84 static 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
95 static 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
103 static const struct device_type l2tpeth_type = {
104 .name = "l2tpeth",
105 };
106
107 static 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
117 static 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 /* drop outer flow-hash */
131 skb_clear_hash(skb);
132
133 skb_dst_drop(skb);
134 nf_reset_ct(skb);
135
136 rcu_read_lock();
137 dev = rcu_dereference(spriv->dev);
138 if (!dev)
139 goto error_rcu;
140
141 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
142 DEV_STATS_INC(dev, rx_packets);
143 DEV_STATS_ADD(dev, rx_bytes, data_len);
144 } else {
145 DEV_STATS_INC(dev, rx_errors);
146 }
147 rcu_read_unlock();
148
149 return;
150
151 error_rcu:
152 rcu_read_unlock();
153 error:
154 kfree_skb(skb);
155 }
156
157 static void l2tp_eth_delete(struct l2tp_session *session)
158 {
159 struct l2tp_eth_sess *spriv;
160 struct net_device *dev;
161
162 if (session) {
163 spriv = l2tp_session_priv(session);
164
165 rtnl_lock();
166 dev = rtnl_dereference(spriv->dev);
167 if (dev) {
168 unregister_netdevice(dev);
169 rtnl_unlock();
170 module_put(THIS_MODULE);
171 } else {
172 rtnl_unlock();
173 }
174 }
175 }
176
177 static void l2tp_eth_show(struct seq_file *m, void *arg)
178 {
179 struct l2tp_session *session = arg;
180 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
181 struct net_device *dev;
182
183 rcu_read_lock();
184 dev = rcu_dereference(spriv->dev);
185 if (!dev) {
186 rcu_read_unlock();
187 return;
188 }
189 dev_hold(dev);
190 rcu_read_unlock();
191
192 seq_printf(m, " interface %s\n", dev->name);
193
194 dev_put(dev);
195 }
196
197 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
198 struct l2tp_session *session,
199 struct net_device *dev)
200 {
201 unsigned int overhead = 0;
202 u32 l3_overhead = 0;
203 u32 mtu;
204
205 /* if the encap is UDP, account for UDP header size */
206 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
207 overhead += sizeof(struct udphdr);
208 dev->needed_headroom += sizeof(struct udphdr);
209 }
210
211 lock_sock(tunnel->sock);
212 l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
213 release_sock(tunnel->sock);
214
215 if (l3_overhead == 0) {
216 /* L3 Overhead couldn't be identified, this could be
217 * because tunnel->sock was NULL or the socket's
218 * address family was not IPv4 or IPv6,
219 * dev mtu stays at 1500.
220 */
221 return;
222 }
223 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
224 * UDP overhead, if any, was already factored in above.
225 */
226 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
227
228 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
229 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
230 dev->mtu = ETH_DATA_LEN - overhead;
231 else
232 dev->mtu = mtu;
233
234 dev->needed_headroom += session->hdr_len;
235 }
236
237 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
238 u32 session_id, u32 peer_session_id,
239 struct l2tp_session_cfg *cfg)
240 {
241 unsigned char name_assign_type;
242 struct net_device *dev;
243 char name[IFNAMSIZ];
244 struct l2tp_session *session;
245 struct l2tp_eth *priv;
246 struct l2tp_eth_sess *spriv;
247 int rc;
248
249 if (cfg->ifname) {
250 strscpy(name, cfg->ifname, IFNAMSIZ);
251 name_assign_type = NET_NAME_USER;
252 } else {
253 strcpy(name, L2TP_ETH_DEV_NAME);
254 name_assign_type = NET_NAME_ENUM;
255 }
256
257 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
258 peer_session_id, cfg);
259 if (IS_ERR(session)) {
260 rc = PTR_ERR(session);
261 goto err;
262 }
263
264 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
265 l2tp_eth_dev_setup);
266 if (!dev) {
267 rc = -ENOMEM;
268 goto err_sess;
269 }
270
271 dev_net_set(dev, net);
272 dev->min_mtu = 0;
273 dev->max_mtu = ETH_MAX_MTU;
274 l2tp_eth_adjust_mtu(tunnel, session, dev);
275
276 priv = netdev_priv(dev);
277 priv->session = session;
278
279 session->recv_skb = l2tp_eth_dev_recv;
280 session->session_close = l2tp_eth_delete;
281 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
282 session->show = l2tp_eth_show;
283
284 spriv = l2tp_session_priv(session);
285
286 l2tp_session_inc_refcount(session);
287
288 rtnl_lock();
289
290 /* Register both device and session while holding the rtnl lock. This
291 * ensures that l2tp_eth_delete() will see that there's a device to
292 * unregister, even if it happened to run before we assign spriv->dev.
293 */
294 rc = l2tp_session_register(session, tunnel);
295 if (rc < 0) {
296 rtnl_unlock();
297 goto err_sess_dev;
298 }
299
300 rc = register_netdevice(dev);
301 if (rc < 0) {
302 rtnl_unlock();
303 l2tp_session_delete(session);
304 l2tp_session_dec_refcount(session);
305 free_netdev(dev);
306
307 return rc;
308 }
309
310 strscpy(session->ifname, dev->name, IFNAMSIZ);
311 rcu_assign_pointer(spriv->dev, dev);
312
313 rtnl_unlock();
314
315 l2tp_session_dec_refcount(session);
316
317 __module_get(THIS_MODULE);
318
319 return 0;
320
321 err_sess_dev:
322 l2tp_session_dec_refcount(session);
323 free_netdev(dev);
324 err_sess:
325 kfree(session);
326 err:
327 return rc;
328 }
329
330 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
331 .session_create = l2tp_eth_create,
332 .session_delete = l2tp_session_delete,
333 };
334
335 static int __init l2tp_eth_init(void)
336 {
337 int err = 0;
338
339 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
340 if (err)
341 goto err;
342
343 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
344
345 return 0;
346
347 err:
348 return err;
349 }
350
351 static void __exit l2tp_eth_exit(void)
352 {
353 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
354 }
355
356 module_init(l2tp_eth_init);
357 module_exit(l2tp_eth_exit);
358
359 MODULE_LICENSE("GPL");
360 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
361 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
362 MODULE_VERSION("1.0");
363 MODULE_ALIAS_L2TP_PWTYPE(5);
364
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