2 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
4 * This code is derived from drivers/net/can/vcan.c for the virtual CAN
5 * specific parts and from drivers/net/veth.c to implement the netlink API
6 * for network interface pairs in a common and established way.
8 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the version 2 of the GNU General Public License
12 * as published by the Free Software Foundation
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, see <http://www.gnu.org/licenses/>.
23 #include <linux/module.h>
24 #include <linux/init.h>
25 #include <linux/netdevice.h>
26 #include <linux/if_arp.h>
27 #include <linux/if_ether.h>
28 #include <linux/can.h>
29 #include <linux/can/dev.h>
30 #include <linux/can/skb.h>
31 #include <linux/can/vxcan.h>
32 #include <linux/slab.h>
33 #include <net/rtnetlink.h>
35 #define DRV_NAME "vxcan"
37 MODULE_DESCRIPTION("Virtual CAN Tunnel");
38 MODULE_LICENSE("GPL");
39 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
40 MODULE_ALIAS_RTNL_LINK(DRV_NAME);
43 struct net_device __rcu *peer;
46 static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev)
48 struct vxcan_priv *priv = netdev_priv(dev);
49 struct net_device *peer;
50 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
51 struct net_device_stats *peerstats, *srcstats = &dev->stats;
54 if (can_dropped_invalid_skb(dev, skb))
58 peer = rcu_dereference(priv->peer);
59 if (unlikely(!peer)) {
61 dev->stats.tx_dropped++;
65 skb = can_create_echo_skb(skb);
69 /* reset CAN GW hop counter */
71 skb->pkt_type = PACKET_BROADCAST;
73 skb->ip_summed = CHECKSUM_UNNECESSARY;
76 if (netif_rx_ni(skb) == NET_RX_SUCCESS) {
77 srcstats->tx_packets++;
78 srcstats->tx_bytes += len;
79 peerstats = &peer->stats;
80 peerstats->rx_packets++;
81 peerstats->rx_bytes += len;
90 static int vxcan_open(struct net_device *dev)
92 struct vxcan_priv *priv = netdev_priv(dev);
93 struct net_device *peer = rtnl_dereference(priv->peer);
98 if (peer->flags & IFF_UP) {
99 netif_carrier_on(dev);
100 netif_carrier_on(peer);
105 static int vxcan_close(struct net_device *dev)
107 struct vxcan_priv *priv = netdev_priv(dev);
108 struct net_device *peer = rtnl_dereference(priv->peer);
110 netif_carrier_off(dev);
112 netif_carrier_off(peer);
117 static int vxcan_get_iflink(const struct net_device *dev)
119 struct vxcan_priv *priv = netdev_priv(dev);
120 struct net_device *peer;
124 peer = rcu_dereference(priv->peer);
125 iflink = peer ? peer->ifindex : 0;
131 static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
133 /* Do not allow changing the MTU while running */
134 if (dev->flags & IFF_UP)
137 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
144 static const struct net_device_ops vxcan_netdev_ops = {
145 .ndo_open = vxcan_open,
146 .ndo_stop = vxcan_close,
147 .ndo_start_xmit = vxcan_xmit,
148 .ndo_get_iflink = vxcan_get_iflink,
149 .ndo_change_mtu = vxcan_change_mtu,
152 static void vxcan_setup(struct net_device *dev)
154 dev->type = ARPHRD_CAN;
155 dev->mtu = CANFD_MTU;
156 dev->hard_header_len = 0;
158 dev->tx_queue_len = 0;
159 dev->flags = (IFF_NOARP|IFF_ECHO);
160 dev->netdev_ops = &vxcan_netdev_ops;
161 dev->needs_free_netdev = true;
164 /* forward declaration for rtnl_create_link() */
165 static struct rtnl_link_ops vxcan_link_ops;
167 static int vxcan_newlink(struct net *net, struct net_device *dev,
168 struct nlattr *tb[], struct nlattr *data[],
169 struct netlink_ext_ack *extack)
171 struct vxcan_priv *priv;
172 struct net_device *peer;
173 struct net *peer_net;
175 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
176 char ifname[IFNAMSIZ];
177 unsigned char name_assign_type;
178 struct ifinfomsg *ifmp = NULL;
181 /* register peer device */
182 if (data && data[VXCAN_INFO_PEER]) {
183 struct nlattr *nla_peer;
185 nla_peer = data[VXCAN_INFO_PEER];
186 ifmp = nla_data(nla_peer);
187 err = rtnl_nla_parse_ifla(peer_tb,
189 sizeof(struct ifinfomsg),
191 sizeof(struct ifinfomsg),
199 if (ifmp && tbp[IFLA_IFNAME]) {
200 nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
201 name_assign_type = NET_NAME_USER;
203 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
204 name_assign_type = NET_NAME_ENUM;
207 peer_net = rtnl_link_get_net(net, tbp);
208 if (IS_ERR(peer_net))
209 return PTR_ERR(peer_net);
211 peer = rtnl_create_link(peer_net, ifname, name_assign_type,
212 &vxcan_link_ops, tbp);
215 return PTR_ERR(peer);
218 if (ifmp && dev->ifindex)
219 peer->ifindex = ifmp->ifi_index;
221 err = register_netdevice(peer);
229 netif_carrier_off(peer);
231 err = rtnl_configure_link(peer, ifmp);
233 unregister_netdevice(peer);
237 /* register first device */
239 nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
241 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
243 err = register_netdevice(dev);
245 unregister_netdevice(peer);
249 netif_carrier_off(dev);
251 /* cross link the device pair */
252 priv = netdev_priv(dev);
253 rcu_assign_pointer(priv->peer, peer);
255 priv = netdev_priv(peer);
256 rcu_assign_pointer(priv->peer, dev);
261 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
263 struct vxcan_priv *priv;
264 struct net_device *peer;
266 priv = netdev_priv(dev);
267 peer = rtnl_dereference(priv->peer);
269 /* Note : dellink() is called from default_device_exit_batch(),
270 * before a rcu_synchronize() point. The devices are guaranteed
271 * not being freed before one RCU grace period.
273 RCU_INIT_POINTER(priv->peer, NULL);
274 unregister_netdevice_queue(dev, head);
277 priv = netdev_priv(peer);
278 RCU_INIT_POINTER(priv->peer, NULL);
279 unregister_netdevice_queue(peer, head);
283 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
284 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
287 static struct net *vxcan_get_link_net(const struct net_device *dev)
289 struct vxcan_priv *priv = netdev_priv(dev);
290 struct net_device *peer = rtnl_dereference(priv->peer);
292 return peer ? dev_net(peer) : dev_net(dev);
295 static struct rtnl_link_ops vxcan_link_ops = {
297 .priv_size = sizeof(struct vxcan_priv),
298 .setup = vxcan_setup,
299 .newlink = vxcan_newlink,
300 .dellink = vxcan_dellink,
301 .policy = vxcan_policy,
302 .maxtype = VXCAN_INFO_MAX,
303 .get_link_net = vxcan_get_link_net,
306 static __init int vxcan_init(void)
308 pr_info("vxcan: Virtual CAN Tunnel driver\n");
310 return rtnl_link_register(&vxcan_link_ops);
313 static __exit void vxcan_exit(void)
315 rtnl_link_unregister(&vxcan_link_ops);
318 module_init(vxcan_init);
319 module_exit(vxcan_exit);