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