xref: /openbmc/linux/net/l2tp/l2tp_eth.c (revision 6aa7de05)
1 /*
2  * L2TPv3 ethernet pseudowire driver
3  *
4  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5  *
6  *	This program is free software; you can redistribute it and/or
7  *	modify it under the terms of the GNU General Public License
8  *	as published by the Free Software Foundation; either version
9  *	2 of the License, or (at your option) any later version.
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/socket.h>
17 #include <linux/hash.h>
18 #include <linux/l2tp.h>
19 #include <linux/in.h>
20 #include <linux/etherdevice.h>
21 #include <linux/spinlock.h>
22 #include <net/sock.h>
23 #include <net/ip.h>
24 #include <net/icmp.h>
25 #include <net/udp.h>
26 #include <net/inet_common.h>
27 #include <net/inet_hashtables.h>
28 #include <net/tcp_states.h>
29 #include <net/protocol.h>
30 #include <net/xfrm.h>
31 #include <net/net_namespace.h>
32 #include <net/netns/generic.h>
33 #include <linux/ip.h>
34 #include <linux/ipv6.h>
35 #include <linux/udp.h>
36 
37 #include "l2tp_core.h"
38 
39 /* Default device name. May be overridden by name specified by user */
40 #define L2TP_ETH_DEV_NAME	"l2tpeth%d"
41 
42 /* via netdev_priv() */
43 struct l2tp_eth {
44 	struct net_device	*dev;
45 	struct sock		*tunnel_sock;
46 	struct l2tp_session	*session;
47 	atomic_long_t		tx_bytes;
48 	atomic_long_t		tx_packets;
49 	atomic_long_t		tx_dropped;
50 	atomic_long_t		rx_bytes;
51 	atomic_long_t		rx_packets;
52 	atomic_long_t		rx_errors;
53 };
54 
55 /* via l2tp_session_priv() */
56 struct l2tp_eth_sess {
57 	struct net_device	*dev;
58 };
59 
60 
61 static int l2tp_eth_dev_init(struct net_device *dev)
62 {
63 	struct l2tp_eth *priv = netdev_priv(dev);
64 
65 	priv->dev = dev;
66 	eth_hw_addr_random(dev);
67 	eth_broadcast_addr(dev->broadcast);
68 	netdev_lockdep_set_classes(dev);
69 
70 	return 0;
71 }
72 
73 static void l2tp_eth_dev_uninit(struct net_device *dev)
74 {
75 	dev_put(dev);
76 }
77 
78 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
79 {
80 	struct l2tp_eth *priv = netdev_priv(dev);
81 	struct l2tp_session *session = priv->session;
82 	unsigned int len = skb->len;
83 	int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
84 
85 	if (likely(ret == NET_XMIT_SUCCESS)) {
86 		atomic_long_add(len, &priv->tx_bytes);
87 		atomic_long_inc(&priv->tx_packets);
88 	} else {
89 		atomic_long_inc(&priv->tx_dropped);
90 	}
91 	return NETDEV_TX_OK;
92 }
93 
94 static void l2tp_eth_get_stats64(struct net_device *dev,
95 				 struct rtnl_link_stats64 *stats)
96 {
97 	struct l2tp_eth *priv = netdev_priv(dev);
98 
99 	stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
100 	stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
101 	stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
102 	stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
103 	stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
104 	stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);
105 
106 }
107 
108 static const struct net_device_ops l2tp_eth_netdev_ops = {
109 	.ndo_init		= l2tp_eth_dev_init,
110 	.ndo_uninit		= l2tp_eth_dev_uninit,
111 	.ndo_start_xmit		= l2tp_eth_dev_xmit,
112 	.ndo_get_stats64	= l2tp_eth_get_stats64,
113 	.ndo_set_mac_address	= eth_mac_addr,
114 };
115 
116 static struct device_type l2tpeth_type = {
117 	.name = "l2tpeth",
118 };
119 
120 static void l2tp_eth_dev_setup(struct net_device *dev)
121 {
122 	SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
123 	ether_setup(dev);
124 	dev->priv_flags		&= ~IFF_TX_SKB_SHARING;
125 	dev->features		|= NETIF_F_LLTX;
126 	dev->netdev_ops		= &l2tp_eth_netdev_ops;
127 	dev->needs_free_netdev	= true;
128 }
129 
130 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
131 {
132 	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
133 	struct net_device *dev = spriv->dev;
134 	struct l2tp_eth *priv = netdev_priv(dev);
135 
136 	if (session->debug & L2TP_MSG_DATA) {
137 		unsigned int length;
138 
139 		length = min(32u, skb->len);
140 		if (!pskb_may_pull(skb, length))
141 			goto error;
142 
143 		pr_debug("%s: eth recv\n", session->name);
144 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
145 	}
146 
147 	if (!pskb_may_pull(skb, ETH_HLEN))
148 		goto error;
149 
150 	secpath_reset(skb);
151 
152 	/* checksums verified by L2TP */
153 	skb->ip_summed = CHECKSUM_NONE;
154 
155 	skb_dst_drop(skb);
156 	nf_reset(skb);
157 
158 	if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
159 		atomic_long_inc(&priv->rx_packets);
160 		atomic_long_add(data_len, &priv->rx_bytes);
161 	} else {
162 		atomic_long_inc(&priv->rx_errors);
163 	}
164 	return;
165 
166 error:
167 	atomic_long_inc(&priv->rx_errors);
168 	kfree_skb(skb);
169 }
170 
171 static void l2tp_eth_delete(struct l2tp_session *session)
172 {
173 	struct l2tp_eth_sess *spriv;
174 	struct net_device *dev;
175 
176 	if (session) {
177 		spriv = l2tp_session_priv(session);
178 		dev = spriv->dev;
179 		if (dev) {
180 			unregister_netdev(dev);
181 			spriv->dev = NULL;
182 			module_put(THIS_MODULE);
183 		}
184 	}
185 }
186 
187 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
188 static void l2tp_eth_show(struct seq_file *m, void *arg)
189 {
190 	struct l2tp_session *session = arg;
191 	struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
192 	struct net_device *dev = spriv->dev;
193 
194 	seq_printf(m, "   interface %s\n", dev->name);
195 }
196 #endif
197 
198 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
199 				struct l2tp_session *session,
200 				struct net_device *dev)
201 {
202 	unsigned int overhead = 0;
203 	struct dst_entry *dst;
204 	u32 l3_overhead = 0;
205 
206 	/* if the encap is UDP, account for UDP header size */
207 	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
208 		overhead += sizeof(struct udphdr);
209 		dev->needed_headroom += sizeof(struct udphdr);
210 	}
211 	if (session->mtu != 0) {
212 		dev->mtu = session->mtu;
213 		dev->needed_headroom += session->hdr_len;
214 		return;
215 	}
216 	lock_sock(tunnel->sock);
217 	l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
218 	release_sock(tunnel->sock);
219 	if (l3_overhead == 0) {
220 		/* L3 Overhead couldn't be identified, this could be
221 		 * because tunnel->sock was NULL or the socket's
222 		 * address family was not IPv4 or IPv6,
223 		 * dev mtu stays at 1500.
224 		 */
225 		return;
226 	}
227 	/* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
228 	 * UDP overhead, if any, was already factored in above.
229 	 */
230 	overhead += session->hdr_len + ETH_HLEN + l3_overhead;
231 
232 	/* If PMTU discovery was enabled, use discovered MTU on L2TP device */
233 	dst = sk_dst_get(tunnel->sock);
234 	if (dst) {
235 		/* dst_mtu will use PMTU if found, else fallback to intf MTU */
236 		u32 pmtu = dst_mtu(dst);
237 
238 		if (pmtu != 0)
239 			dev->mtu = pmtu;
240 		dst_release(dst);
241 	}
242 	session->mtu = dev->mtu - overhead;
243 	dev->mtu = session->mtu;
244 	dev->needed_headroom += session->hdr_len;
245 }
246 
247 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
248 			   u32 session_id, u32 peer_session_id,
249 			   struct l2tp_session_cfg *cfg)
250 {
251 	unsigned char name_assign_type;
252 	struct net_device *dev;
253 	char name[IFNAMSIZ];
254 	struct l2tp_session *session;
255 	struct l2tp_eth *priv;
256 	struct l2tp_eth_sess *spriv;
257 	int rc;
258 
259 	if (cfg->ifname) {
260 		strlcpy(name, cfg->ifname, IFNAMSIZ);
261 		name_assign_type = NET_NAME_USER;
262 	} else {
263 		strcpy(name, L2TP_ETH_DEV_NAME);
264 		name_assign_type = NET_NAME_ENUM;
265 	}
266 
267 	session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
268 				      peer_session_id, cfg);
269 	if (IS_ERR(session)) {
270 		rc = PTR_ERR(session);
271 		goto out;
272 	}
273 
274 	dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
275 			   l2tp_eth_dev_setup);
276 	if (!dev) {
277 		rc = -ENOMEM;
278 		goto out_del_session;
279 	}
280 
281 	dev_net_set(dev, net);
282 	dev->min_mtu = 0;
283 	dev->max_mtu = ETH_MAX_MTU;
284 	l2tp_eth_adjust_mtu(tunnel, session, dev);
285 
286 	priv = netdev_priv(dev);
287 	priv->dev = dev;
288 	priv->session = session;
289 
290 	priv->tunnel_sock = tunnel->sock;
291 	session->recv_skb = l2tp_eth_dev_recv;
292 	session->session_close = l2tp_eth_delete;
293 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
294 	session->show = l2tp_eth_show;
295 #endif
296 
297 	spriv = l2tp_session_priv(session);
298 	spriv->dev = dev;
299 
300 	rc = register_netdev(dev);
301 	if (rc < 0)
302 		goto out_del_dev;
303 
304 	__module_get(THIS_MODULE);
305 	/* Must be done after register_netdev() */
306 	strlcpy(session->ifname, dev->name, IFNAMSIZ);
307 
308 	dev_hold(dev);
309 
310 	return 0;
311 
312 out_del_dev:
313 	free_netdev(dev);
314 	spriv->dev = NULL;
315 out_del_session:
316 	l2tp_session_delete(session);
317 out:
318 	return rc;
319 }
320 
321 
322 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
323 	.session_create	= l2tp_eth_create,
324 	.session_delete	= l2tp_session_delete,
325 };
326 
327 
328 static int __init l2tp_eth_init(void)
329 {
330 	int err = 0;
331 
332 	err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
333 	if (err)
334 		goto err;
335 
336 	pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
337 
338 	return 0;
339 
340 err:
341 	return err;
342 }
343 
344 static void __exit l2tp_eth_exit(void)
345 {
346 	l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
347 }
348 
349 module_init(l2tp_eth_init);
350 module_exit(l2tp_eth_exit);
351 
352 MODULE_LICENSE("GPL");
353 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
354 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
355 MODULE_VERSION("1.0");
356 MODULE_ALIAS_L2TP_PWTYPE(5);
357