1 // SPDX-License-Identifier: GPL-2.0-only
3 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
5 * This code is derived from drivers/net/can/vcan.c for the virtual CAN
6 * specific parts and from drivers/net/veth.c to implement the netlink API
7 * for network interface pairs in a common and established way.
9 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/netdevice.h>
15 #include <linux/if_arp.h>
16 #include <linux/if_ether.h>
17 #include <linux/can.h>
18 #include <linux/can/dev.h>
19 #include <linux/can/skb.h>
20 #include <linux/can/vxcan.h>
21 #include <linux/can/can-ml.h>
22 #include <linux/slab.h>
23 #include <net/rtnetlink.h>
25 #define DRV_NAME "vxcan"
27 MODULE_DESCRIPTION("Virtual CAN Tunnel");
28 MODULE_LICENSE("GPL");
29 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
30 MODULE_ALIAS_RTNL_LINK(DRV_NAME);
33 struct net_device __rcu *peer;
36 static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev)
38 struct vxcan_priv *priv = netdev_priv(dev);
39 struct net_device *peer;
40 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
41 struct net_device_stats *peerstats, *srcstats = &dev->stats;
44 if (can_dropped_invalid_skb(dev, skb))
48 peer = rcu_dereference(priv->peer);
49 if (unlikely(!peer)) {
51 dev->stats.tx_dropped++;
55 skb = can_create_echo_skb(skb);
59 /* reset CAN GW hop counter */
61 skb->pkt_type = PACKET_BROADCAST;
63 skb->ip_summed = CHECKSUM_UNNECESSARY;
66 if (netif_rx_ni(skb) == NET_RX_SUCCESS) {
67 srcstats->tx_packets++;
68 srcstats->tx_bytes += len;
69 peerstats = &peer->stats;
70 peerstats->rx_packets++;
71 peerstats->rx_bytes += len;
80 static int vxcan_open(struct net_device *dev)
82 struct vxcan_priv *priv = netdev_priv(dev);
83 struct net_device *peer = rtnl_dereference(priv->peer);
88 if (peer->flags & IFF_UP) {
89 netif_carrier_on(dev);
90 netif_carrier_on(peer);
95 static int vxcan_close(struct net_device *dev)
97 struct vxcan_priv *priv = netdev_priv(dev);
98 struct net_device *peer = rtnl_dereference(priv->peer);
100 netif_carrier_off(dev);
102 netif_carrier_off(peer);
107 static int vxcan_get_iflink(const struct net_device *dev)
109 struct vxcan_priv *priv = netdev_priv(dev);
110 struct net_device *peer;
114 peer = rcu_dereference(priv->peer);
115 iflink = peer ? peer->ifindex : 0;
121 static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
123 /* Do not allow changing the MTU while running */
124 if (dev->flags & IFF_UP)
127 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
134 static const struct net_device_ops vxcan_netdev_ops = {
135 .ndo_open = vxcan_open,
136 .ndo_stop = vxcan_close,
137 .ndo_start_xmit = vxcan_xmit,
138 .ndo_get_iflink = vxcan_get_iflink,
139 .ndo_change_mtu = vxcan_change_mtu,
142 static void vxcan_setup(struct net_device *dev)
144 dev->type = ARPHRD_CAN;
145 dev->mtu = CANFD_MTU;
146 dev->hard_header_len = 0;
148 dev->tx_queue_len = 0;
149 dev->flags = (IFF_NOARP|IFF_ECHO);
150 dev->netdev_ops = &vxcan_netdev_ops;
151 dev->needs_free_netdev = true;
152 dev->ml_priv = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
155 /* forward declaration for rtnl_create_link() */
156 static struct rtnl_link_ops vxcan_link_ops;
158 static int vxcan_newlink(struct net *net, struct net_device *dev,
159 struct nlattr *tb[], struct nlattr *data[],
160 struct netlink_ext_ack *extack)
162 struct vxcan_priv *priv;
163 struct net_device *peer;
164 struct net *peer_net;
166 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
167 char ifname[IFNAMSIZ];
168 unsigned char name_assign_type;
169 struct ifinfomsg *ifmp = NULL;
172 /* register peer device */
173 if (data && data[VXCAN_INFO_PEER]) {
174 struct nlattr *nla_peer;
176 nla_peer = data[VXCAN_INFO_PEER];
177 ifmp = nla_data(nla_peer);
178 err = rtnl_nla_parse_ifla(peer_tb,
180 sizeof(struct ifinfomsg),
182 sizeof(struct ifinfomsg),
190 if (ifmp && tbp[IFLA_IFNAME]) {
191 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
192 name_assign_type = NET_NAME_USER;
194 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
195 name_assign_type = NET_NAME_ENUM;
198 peer_net = rtnl_link_get_net(net, tbp);
199 if (IS_ERR(peer_net))
200 return PTR_ERR(peer_net);
202 peer = rtnl_create_link(peer_net, ifname, name_assign_type,
203 &vxcan_link_ops, tbp, extack);
206 return PTR_ERR(peer);
209 if (ifmp && dev->ifindex)
210 peer->ifindex = ifmp->ifi_index;
212 err = register_netdevice(peer);
220 netif_carrier_off(peer);
222 err = rtnl_configure_link(peer, ifmp);
224 goto unregister_network_device;
226 /* register first device */
228 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
230 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
232 err = register_netdevice(dev);
234 goto unregister_network_device;
236 netif_carrier_off(dev);
238 /* cross link the device pair */
239 priv = netdev_priv(dev);
240 rcu_assign_pointer(priv->peer, peer);
242 priv = netdev_priv(peer);
243 rcu_assign_pointer(priv->peer, dev);
247 unregister_network_device:
248 unregister_netdevice(peer);
252 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
254 struct vxcan_priv *priv;
255 struct net_device *peer;
257 priv = netdev_priv(dev);
258 peer = rtnl_dereference(priv->peer);
260 /* Note : dellink() is called from default_device_exit_batch(),
261 * before a rcu_synchronize() point. The devices are guaranteed
262 * not being freed before one RCU grace period.
264 RCU_INIT_POINTER(priv->peer, NULL);
265 unregister_netdevice_queue(dev, head);
268 priv = netdev_priv(peer);
269 RCU_INIT_POINTER(priv->peer, NULL);
270 unregister_netdevice_queue(peer, head);
274 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
275 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
278 static struct net *vxcan_get_link_net(const struct net_device *dev)
280 struct vxcan_priv *priv = netdev_priv(dev);
281 struct net_device *peer = rtnl_dereference(priv->peer);
283 return peer ? dev_net(peer) : dev_net(dev);
286 static struct rtnl_link_ops vxcan_link_ops = {
288 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv),
289 .setup = vxcan_setup,
290 .newlink = vxcan_newlink,
291 .dellink = vxcan_dellink,
292 .policy = vxcan_policy,
293 .maxtype = VXCAN_INFO_MAX,
294 .get_link_net = vxcan_get_link_net,
297 static __init int vxcan_init(void)
299 pr_info("vxcan: Virtual CAN Tunnel driver\n");
301 return rtnl_link_register(&vxcan_link_ops);
304 static __exit void vxcan_exit(void)
306 rtnl_link_unregister(&vxcan_link_ops);
309 module_init(vxcan_init);
310 module_exit(vxcan_exit);