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 *oskb, 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 *)oskb->data;
41 struct net_device_stats *peerstats, *srcstats = &dev->stats;
45 if (can_dropped_invalid_skb(dev, oskb))
49 peer = rcu_dereference(priv->peer);
50 if (unlikely(!peer)) {
52 dev->stats.tx_dropped++;
56 skb = skb_clone(oskb, GFP_ATOMIC);
64 /* reset CAN GW hop counter */
66 skb->pkt_type = PACKET_BROADCAST;
68 skb->ip_summed = CHECKSUM_UNNECESSARY;
70 len = cfd->can_id & CAN_RTR_FLAG ? 0 : cfd->len;
71 if (netif_rx(skb) == NET_RX_SUCCESS) {
72 srcstats->tx_packets++;
73 srcstats->tx_bytes += len;
74 peerstats = &peer->stats;
75 peerstats->rx_packets++;
76 peerstats->rx_bytes += len;
85 static int vxcan_open(struct net_device *dev)
87 struct vxcan_priv *priv = netdev_priv(dev);
88 struct net_device *peer = rtnl_dereference(priv->peer);
93 if (peer->flags & IFF_UP) {
94 netif_carrier_on(dev);
95 netif_carrier_on(peer);
100 static int vxcan_close(struct net_device *dev)
102 struct vxcan_priv *priv = netdev_priv(dev);
103 struct net_device *peer = rtnl_dereference(priv->peer);
105 netif_carrier_off(dev);
107 netif_carrier_off(peer);
112 static int vxcan_get_iflink(const struct net_device *dev)
114 struct vxcan_priv *priv = netdev_priv(dev);
115 struct net_device *peer;
119 peer = rcu_dereference(priv->peer);
120 iflink = peer ? peer->ifindex : 0;
126 static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
128 /* Do not allow changing the MTU while running */
129 if (dev->flags & IFF_UP)
132 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
139 static const struct net_device_ops vxcan_netdev_ops = {
140 .ndo_open = vxcan_open,
141 .ndo_stop = vxcan_close,
142 .ndo_start_xmit = vxcan_xmit,
143 .ndo_get_iflink = vxcan_get_iflink,
144 .ndo_change_mtu = vxcan_change_mtu,
147 static void vxcan_setup(struct net_device *dev)
149 struct can_ml_priv *can_ml;
151 dev->type = ARPHRD_CAN;
152 dev->mtu = CANFD_MTU;
153 dev->hard_header_len = 0;
155 dev->tx_queue_len = 0;
156 dev->flags = IFF_NOARP;
157 dev->netdev_ops = &vxcan_netdev_ops;
158 dev->needs_free_netdev = true;
160 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
161 can_set_ml_priv(dev, can_ml);
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_strscpy(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, extack);
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 goto unregister_network_device;
235 /* register first device */
237 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
239 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
241 err = register_netdevice(dev);
243 goto unregister_network_device;
245 netif_carrier_off(dev);
247 /* cross link the device pair */
248 priv = netdev_priv(dev);
249 rcu_assign_pointer(priv->peer, peer);
251 priv = netdev_priv(peer);
252 rcu_assign_pointer(priv->peer, dev);
256 unregister_network_device:
257 unregister_netdevice(peer);
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 = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_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);