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(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(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 | |
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 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 | 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 | |
148 | error_rcu: |
149 | rcu_read_unlock(); |
150 | error: |
151 | kfree_skb(skb); |
152 | } |
153 | |
154 | static 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 | |
174 | static 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 | |
194 | static 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 | |
234 | static 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 | |
318 | err_sess_dev: |
319 | l2tp_session_dec_refcount(session); |
320 | free_netdev(dev); |
321 | err_sess: |
322 | kfree(objp: session); |
323 | err: |
324 | return rc; |
325 | } |
326 | |
327 | static 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 | |
332 | static 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 | |
344 | err: |
345 | return err; |
346 | } |
347 | |
348 | static void __exit l2tp_eth_exit(void) |
349 | { |
350 | l2tp_nl_unregister_ops(pw_type: L2TP_PWTYPE_ETH); |
351 | } |
352 | |
353 | module_init(l2tp_eth_init); |
354 | module_exit(l2tp_eth_exit); |
355 | |
356 | MODULE_LICENSE("GPL" ); |
357 | MODULE_AUTHOR("James Chapman <jchapman@katalix.com>" ); |
358 | MODULE_DESCRIPTION("L2TP ethernet pseudowire driver" ); |
359 | MODULE_VERSION("1.0" ); |
360 | MODULE_ALIAS_L2TP_PWTYPE(5); |
361 | |