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 <net/netdev_lock.h>
29#include <linux/ip.h>
30#include <linux/ipv6.h>
31#include <linux/udp.h>
32
33#include "l2tp_core.h"
34
35/* Default device name. May be overridden by name specified by user */
36#define L2TP_ETH_DEV_NAME "l2tpeth%d"
37
38/* via netdev_priv() */
39struct l2tp_eth {
40 struct l2tp_session *session;
41};
42
43/* via l2tp_session_priv() */
44struct l2tp_eth_sess {
45 struct net_device __rcu *dev;
46};
47
48static int l2tp_eth_dev_init(struct net_device *dev)
49{
50 eth_hw_addr_random(dev);
51 eth_broadcast_addr(addr: dev->broadcast);
52 netdev_lockdep_set_classes(dev);
53
54 return 0;
55}
56
57static void l2tp_eth_dev_uninit(struct net_device *dev)
58{
59 struct l2tp_eth *priv = netdev_priv(dev);
60 struct l2tp_eth_sess *spriv;
61
62 spriv = l2tp_session_priv(session: priv->session);
63 RCU_INIT_POINTER(spriv->dev, NULL);
64 /* No need for synchronize_net() here. We're called by
65 * unregister_netdev*(), which does the synchronisation for us.
66 */
67}
68
69static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
70{
71 struct l2tp_eth *priv = netdev_priv(dev);
72 struct l2tp_session *session = priv->session;
73 unsigned int len = skb->len;
74 int ret = l2tp_xmit_skb(session, skb);
75
76 if (likely(ret == NET_XMIT_SUCCESS))
77 dev_dstats_tx_add(dev, len);
78 else
79 dev_dstats_tx_dropped(dev);
80
81 return NETDEV_TX_OK;
82}
83
84static const struct net_device_ops l2tp_eth_netdev_ops = {
85 .ndo_init = l2tp_eth_dev_init,
86 .ndo_uninit = l2tp_eth_dev_uninit,
87 .ndo_start_xmit = l2tp_eth_dev_xmit,
88 .ndo_set_mac_address = eth_mac_addr,
89};
90
91static const struct device_type l2tpeth_type = {
92 .name = "l2tpeth",
93};
94
95static void l2tp_eth_dev_setup(struct net_device *dev)
96{
97 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
98 ether_setup(dev);
99 dev->priv_flags &= ~IFF_TX_SKB_SHARING;
100 dev->lltx = true;
101 dev->netdev_ops = &l2tp_eth_netdev_ops;
102 dev->needs_free_netdev = true;
103 dev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS;
104}
105
106static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
107{
108 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
109 struct net_device *dev;
110
111 if (!pskb_may_pull(skb, ETH_HLEN))
112 goto error;
113
114 secpath_reset(skb);
115
116 /* checksums verified by L2TP */
117 skb->ip_summed = CHECKSUM_NONE;
118
119 /* drop outer flow-hash */
120 skb_clear_hash(skb);
121
122 skb_dst_drop(skb);
123 nf_reset_ct(skb);
124
125 rcu_read_lock();
126 dev = rcu_dereference(spriv->dev);
127 if (!dev)
128 goto error_rcu;
129
130 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS)
131 dev_dstats_rx_add(dev, len: data_len);
132 else
133 DEV_STATS_INC(dev, rx_errors);
134
135 rcu_read_unlock();
136
137 return;
138
139error_rcu:
140 rcu_read_unlock();
141error:
142 kfree_skb(skb);
143}
144
145static void l2tp_eth_delete(struct l2tp_session *session)
146{
147 struct l2tp_eth_sess *spriv;
148 struct net_device *dev;
149
150 if (session) {
151 spriv = l2tp_session_priv(session);
152
153 rtnl_lock();
154 dev = rtnl_dereference(spriv->dev);
155 if (dev) {
156 unregister_netdevice(dev);
157 rtnl_unlock();
158 module_put(THIS_MODULE);
159 } else {
160 rtnl_unlock();
161 }
162 }
163}
164
165static void l2tp_eth_show(struct seq_file *m, void *arg)
166{
167 struct l2tp_session *session = arg;
168 struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
169 struct net_device *dev;
170
171 rcu_read_lock();
172 dev = rcu_dereference(spriv->dev);
173 if (!dev) {
174 rcu_read_unlock();
175 return;
176 }
177 dev_hold(dev);
178 rcu_read_unlock();
179
180 seq_printf(m, fmt: " interface %s\n", dev->name);
181
182 dev_put(dev);
183}
184
185static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
186 struct l2tp_session *session,
187 struct net_device *dev)
188{
189 unsigned int overhead = 0;
190 u32 l3_overhead = 0;
191 u32 mtu;
192
193 /* if the encap is UDP, account for UDP header size */
194 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
195 overhead += sizeof(struct udphdr);
196 dev->needed_headroom += sizeof(struct udphdr);
197 }
198
199 lock_sock(sk: tunnel->sock);
200 l3_overhead = kernel_sock_ip_overhead(sk: tunnel->sock);
201 release_sock(sk: tunnel->sock);
202
203 if (l3_overhead == 0) {
204 /* L3 Overhead couldn't be identified, this could be
205 * because tunnel->sock was NULL or the socket's
206 * address family was not IPv4 or IPv6,
207 * dev mtu stays at 1500.
208 */
209 return;
210 }
211 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
212 * UDP overhead, if any, was already factored in above.
213 */
214 overhead += session->hdr_len + ETH_HLEN + l3_overhead;
215
216 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
217 if (mtu < dev->min_mtu || mtu > dev->max_mtu)
218 dev->mtu = ETH_DATA_LEN - overhead;
219 else
220 dev->mtu = mtu;
221
222 dev->needed_headroom += session->hdr_len;
223}
224
225static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
226 u32 session_id, u32 peer_session_id,
227 struct l2tp_session_cfg *cfg)
228{
229 unsigned char name_assign_type;
230 struct net_device *dev;
231 char name[IFNAMSIZ];
232 struct l2tp_session *session;
233 struct l2tp_eth *priv;
234 struct l2tp_eth_sess *spriv;
235 int rc;
236
237 if (cfg->ifname) {
238 strscpy(name, cfg->ifname, IFNAMSIZ);
239 name_assign_type = NET_NAME_USER;
240 } else {
241 strcpy(p: name, L2TP_ETH_DEV_NAME);
242 name_assign_type = NET_NAME_ENUM;
243 }
244
245 session = l2tp_session_create(priv_size: sizeof(*spriv), tunnel, session_id,
246 peer_session_id, cfg);
247 if (IS_ERR(ptr: session)) {
248 rc = PTR_ERR(ptr: session);
249 goto err;
250 }
251
252 dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
253 l2tp_eth_dev_setup);
254 if (!dev) {
255 rc = -ENOMEM;
256 goto err_sess;
257 }
258
259 dev_net_set(dev, net);
260 dev->min_mtu = 0;
261 dev->max_mtu = ETH_MAX_MTU;
262 l2tp_eth_adjust_mtu(tunnel, session, dev);
263
264 priv = netdev_priv(dev);
265 priv->session = session;
266
267 session->recv_skb = l2tp_eth_dev_recv;
268 session->session_close = l2tp_eth_delete;
269 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
270 session->show = l2tp_eth_show;
271
272 spriv = l2tp_session_priv(session);
273
274 refcount_inc(r: &session->ref_count);
275
276 rtnl_lock();
277
278 /* Register both device and session while holding the rtnl lock. This
279 * ensures that l2tp_eth_delete() will see that there's a device to
280 * unregister, even if it happened to run before we assign spriv->dev.
281 */
282 rc = l2tp_session_register(session, tunnel);
283 if (rc < 0) {
284 rtnl_unlock();
285 goto err_sess_dev;
286 }
287
288 rc = register_netdevice(dev);
289 if (rc < 0) {
290 rtnl_unlock();
291 l2tp_session_delete(session);
292 l2tp_session_put(session);
293 free_netdev(dev);
294
295 return rc;
296 }
297
298 strscpy(session->ifname, dev->name, IFNAMSIZ);
299 rcu_assign_pointer(spriv->dev, dev);
300
301 rtnl_unlock();
302
303 l2tp_session_put(session);
304
305 __module_get(THIS_MODULE);
306
307 return 0;
308
309err_sess_dev:
310 l2tp_session_put(session);
311 free_netdev(dev);
312err_sess:
313 l2tp_session_put(session);
314err:
315 return rc;
316}
317
318static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
319 .session_create = l2tp_eth_create,
320 .session_delete = l2tp_session_delete,
321};
322
323static int __init l2tp_eth_init(void)
324{
325 int err = 0;
326
327 err = l2tp_nl_register_ops(pw_type: L2TP_PWTYPE_ETH, ops: &l2tp_eth_nl_cmd_ops);
328 if (err)
329 goto err;
330
331 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
332
333 return 0;
334
335err:
336 return err;
337}
338
339static void __exit l2tp_eth_exit(void)
340{
341 l2tp_nl_unregister_ops(pw_type: L2TP_PWTYPE_ETH);
342}
343
344module_init(l2tp_eth_init);
345module_exit(l2tp_eth_exit);
346
347MODULE_LICENSE("GPL");
348MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
349MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
350MODULE_VERSION("1.0");
351MODULE_ALIAS_L2TP_PWTYPE(5);
352

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