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 struct can_ml_priv *can_ml;
146 dev->type = ARPHRD_CAN;
147 dev->mtu = CANFD_MTU;
148 dev->hard_header_len = 0;
150 dev->tx_queue_len = 0;
151 dev->flags = IFF_NOARP;
152 dev->netdev_ops = &vxcan_netdev_ops;
153 dev->needs_free_netdev = true;
155 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
156 can_set_ml_priv(dev, can_ml);
159 /* forward declaration for rtnl_create_link() */
160 static struct rtnl_link_ops vxcan_link_ops;
162 static int vxcan_newlink(struct net *net, struct net_device *dev,
163 struct nlattr *tb[], struct nlattr *data[],
164 struct netlink_ext_ack *extack)
166 struct vxcan_priv *priv;
167 struct net_device *peer;
168 struct net *peer_net;
170 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
171 char ifname[IFNAMSIZ];
172 unsigned char name_assign_type;
173 struct ifinfomsg *ifmp = NULL;
176 /* register peer device */
177 if (data && data[VXCAN_INFO_PEER]) {
178 struct nlattr *nla_peer;
180 nla_peer = data[VXCAN_INFO_PEER];
181 ifmp = nla_data(nla_peer);
182 err = rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack);
189 if (ifmp && tbp[IFLA_IFNAME]) {
190 nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
191 name_assign_type = NET_NAME_USER;
193 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
194 name_assign_type = NET_NAME_ENUM;
197 peer_net = rtnl_link_get_net(net, tbp);
198 if (IS_ERR(peer_net))
199 return PTR_ERR(peer_net);
201 peer = rtnl_create_link(peer_net, ifname, name_assign_type,
202 &vxcan_link_ops, tbp, extack);
205 return PTR_ERR(peer);
208 if (ifmp && dev->ifindex)
209 peer->ifindex = ifmp->ifi_index;
211 err = register_netdevice(peer);
219 netif_carrier_off(peer);
221 err = rtnl_configure_link(peer, ifmp);
223 goto unregister_network_device;
225 /* register first device */
227 nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
229 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
231 err = register_netdevice(dev);
233 goto unregister_network_device;
235 netif_carrier_off(dev);
237 /* cross link the device pair */
238 priv = netdev_priv(dev);
239 rcu_assign_pointer(priv->peer, peer);
241 priv = netdev_priv(peer);
242 rcu_assign_pointer(priv->peer, dev);
246 unregister_network_device:
247 unregister_netdevice(peer);
251 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
253 struct vxcan_priv *priv;
254 struct net_device *peer;
256 priv = netdev_priv(dev);
257 peer = rtnl_dereference(priv->peer);
259 /* Note : dellink() is called from default_device_exit_batch(),
260 * before a rcu_synchronize() point. The devices are guaranteed
261 * not being freed before one RCU grace period.
263 RCU_INIT_POINTER(priv->peer, NULL);
264 unregister_netdevice_queue(dev, head);
267 priv = netdev_priv(peer);
268 RCU_INIT_POINTER(priv->peer, NULL);
269 unregister_netdevice_queue(peer, head);
273 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
274 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
277 static struct net *vxcan_get_link_net(const struct net_device *dev)
279 struct vxcan_priv *priv = netdev_priv(dev);
280 struct net_device *peer = rtnl_dereference(priv->peer);
282 return peer ? dev_net(peer) : dev_net(dev);
285 static struct rtnl_link_ops vxcan_link_ops = {
287 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv),
288 .setup = vxcan_setup,
289 .newlink = vxcan_newlink,
290 .dellink = vxcan_dellink,
291 .policy = vxcan_policy,
292 .maxtype = VXCAN_INFO_MAX,
293 .get_link_net = vxcan_get_link_net,
296 static __init int vxcan_init(void)
298 pr_info("vxcan: Virtual CAN Tunnel driver\n");
300 return rtnl_link_register(&vxcan_link_ops);
303 static __exit void vxcan_exit(void)
305 rtnl_link_unregister(&vxcan_link_ops);
308 module_init(vxcan_init);
309 module_exit(vxcan_exit);