summaryrefslogtreecommitdiffstats
path: root/drivers/net/can/vxcan.c
blob: 8404e8852a0f96df80d7cb3d1059e64890405949 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
/*
 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
 *
 * This code is derived from drivers/net/can/vcan.c for the virtual CAN
 * specific parts and from drivers/net/veth.c to implement the netlink API
 * for network interface pairs in a common and established way.
 *
 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
#include <linux/can/vxcan.h>
#include <linux/slab.h>
#include <net/rtnetlink.h>

#define DRV_NAME "vxcan"

MODULE_DESCRIPTION("Virtual CAN Tunnel");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
MODULE_ALIAS_RTNL_LINK(DRV_NAME);

struct vxcan_priv {
	struct net_device __rcu	*peer;
};

static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer;
	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
	struct net_device_stats *peerstats, *srcstats = &dev->stats;

	if (can_dropped_invalid_skb(dev, skb))
		return NETDEV_TX_OK;

	rcu_read_lock();
	peer = rcu_dereference(priv->peer);
	if (unlikely(!peer)) {
		kfree_skb(skb);
		dev->stats.tx_dropped++;
		goto out_unlock;
	}

	skb = can_create_echo_skb(skb);
	if (!skb)
		goto out_unlock;

	/* reset CAN GW hop counter */
	skb->csum_start = 0;
	skb->pkt_type   = PACKET_BROADCAST;
	skb->dev        = peer;
	skb->ip_summed  = CHECKSUM_UNNECESSARY;

	if (netif_rx_ni(skb) == NET_RX_SUCCESS) {
		srcstats->tx_packets++;
		srcstats->tx_bytes += cfd->len;
		peerstats = &peer->stats;
		peerstats->rx_packets++;
		peerstats->rx_bytes += cfd->len;
	}

out_unlock:
	rcu_read_unlock();
	return NETDEV_TX_OK;
}


static int vxcan_open(struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	if (!peer)
		return -ENOTCONN;

	if (peer->flags & IFF_UP) {
		netif_carrier_on(dev);
		netif_carrier_on(peer);
	}
	return 0;
}

static int vxcan_close(struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	netif_carrier_off(dev);
	if (peer)
		netif_carrier_off(peer);

	return 0;
}

static int vxcan_get_iflink(const struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer;
	int iflink;

	rcu_read_lock();
	peer = rcu_dereference(priv->peer);
	iflink = peer ? peer->ifindex : 0;
	rcu_read_unlock();

	return iflink;
}

static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
{
	/* Do not allow changing the MTU while running */
	if (dev->flags & IFF_UP)
		return -EBUSY;

	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
		return -EINVAL;

	dev->mtu = new_mtu;
	return 0;
}

static const struct net_device_ops vxcan_netdev_ops = {
	.ndo_open	= vxcan_open,
	.ndo_stop	= vxcan_close,
	.ndo_start_xmit	= vxcan_xmit,
	.ndo_get_iflink	= vxcan_get_iflink,
	.ndo_change_mtu = vxcan_change_mtu,
};

static void vxcan_setup(struct net_device *dev)
{
	dev->type		= ARPHRD_CAN;
	dev->mtu		= CANFD_MTU;
	dev->hard_header_len	= 0;
	dev->addr_len		= 0;
	dev->tx_queue_len	= 0;
	dev->flags		= (IFF_NOARP|IFF_ECHO);
	dev->netdev_ops		= &vxcan_netdev_ops;
	dev->needs_free_netdev	= true;
}

/* forward declaration for rtnl_create_link() */
static struct rtnl_link_ops vxcan_link_ops;

static int vxcan_newlink(struct net *net, struct net_device *dev,
			 struct nlattr *tb[], struct nlattr *data[],
			 struct netlink_ext_ack *extack)
{
	struct vxcan_priv *priv;
	struct net_device *peer;
	struct net *peer_net;

	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
	char ifname[IFNAMSIZ];
	unsigned char name_assign_type;
	struct ifinfomsg *ifmp = NULL;
	int err;

	/* register peer device */
	if (data && data[VXCAN_INFO_PEER]) {
		struct nlattr *nla_peer;

		nla_peer = data[VXCAN_INFO_PEER];
		ifmp = nla_data(nla_peer);
		err = rtnl_nla_parse_ifla(peer_tb,
					  nla_data(nla_peer) +
					  sizeof(struct ifinfomsg),
					  nla_len(nla_peer) -
					  sizeof(struct ifinfomsg),
					  NULL);
		if (err < 0)
			return err;

		tbp = peer_tb;
	}

	if (tbp[IFLA_IFNAME]) {
		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
		name_assign_type = NET_NAME_USER;
	} else {
		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
		name_assign_type = NET_NAME_ENUM;
	}

	peer_net = rtnl_link_get_net(net, tbp);
	if (IS_ERR(peer_net))
		return PTR_ERR(peer_net);

	peer = rtnl_create_link(peer_net, ifname, name_assign_type,
				&vxcan_link_ops, tbp);
	if (IS_ERR(peer)) {
		put_net(peer_net);
		return PTR_ERR(peer);
	}

	if (ifmp && dev->ifindex)
		peer->ifindex = ifmp->ifi_index;

	err = register_netdevice(peer);
	put_net(peer_net);
	peer_net = NULL;
	if (err < 0) {
		free_netdev(peer);
		return err;
	}

	netif_carrier_off(peer);

	err = rtnl_configure_link(peer, ifmp);
	if (err < 0) {
		unregister_netdevice(peer);
		return err;
	}

	/* register first device */
	if (tb[IFLA_IFNAME])
		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
	else
		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");

	err = register_netdevice(dev);
	if (err < 0) {
		unregister_netdevice(peer);
		return err;
	}

	netif_carrier_off(dev);

	/* cross link the device pair */
	priv = netdev_priv(dev);
	rcu_assign_pointer(priv->peer, peer);

	priv = netdev_priv(peer);
	rcu_assign_pointer(priv->peer, dev);

	return 0;
}

static void vxcan_dellink(struct net_device *dev, struct list_head *head)
{
	struct vxcan_priv *priv;
	struct net_device *peer;

	priv = netdev_priv(dev);
	peer = rtnl_dereference(priv->peer);

	/* Note : dellink() is called from default_device_exit_batch(),
	 * before a rcu_synchronize() point. The devices are guaranteed
	 * not being freed before one RCU grace period.
	 */
	RCU_INIT_POINTER(priv->peer, NULL);
	unregister_netdevice_queue(dev, head);

	if (peer) {
		priv = netdev_priv(peer);
		RCU_INIT_POINTER(priv->peer, NULL);
		unregister_netdevice_queue(peer, head);
	}
}

static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
	[VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
};

static struct net *vxcan_get_link_net(const struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	return peer ? dev_net(peer) : dev_net(dev);
}

static struct rtnl_link_ops vxcan_link_ops = {
	.kind		= DRV_NAME,
	.priv_size	= sizeof(struct vxcan_priv),
	.setup		= vxcan_setup,
	.newlink	= vxcan_newlink,
	.dellink	= vxcan_dellink,
	.policy		= vxcan_policy,
	.maxtype	= VXCAN_INFO_MAX,
	.get_link_net	= vxcan_get_link_net,
};

static __init int vxcan_init(void)
{
	pr_info("vxcan: Virtual CAN Tunnel driver\n");

	return rtnl_link_register(&vxcan_link_ops);
}

static __exit void vxcan_exit(void)
{
	rtnl_link_unregister(&vxcan_link_ops);
}

module_init(vxcan_init);
module_exit(vxcan_exit);