1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
4 *
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.
8 *
9 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
10 */
11
12 #include <linux/ethtool.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/netdevice.h>
16 #include <linux/if_arp.h>
17 #include <linux/if_ether.h>
18 #include <linux/can.h>
19 #include <linux/can/dev.h>
20 #include <linux/can/skb.h>
21 #include <linux/can/vxcan.h>
22 #include <linux/can/can-ml.h>
23 #include <linux/slab.h>
24 #include <net/rtnetlink.h>
25
26 #define DRV_NAME "vxcan"
27
28 MODULE_DESCRIPTION("Virtual CAN Tunnel");
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
31 MODULE_ALIAS_RTNL_LINK(DRV_NAME);
32
33 struct vxcan_priv {
34 struct net_device __rcu *peer;
35 };
36
vxcan_xmit(struct sk_buff * oskb,struct net_device * dev)37 static netdev_tx_t vxcan_xmit(struct sk_buff *oskb, struct net_device *dev)
38 {
39 struct vxcan_priv *priv = netdev_priv(dev);
40 struct net_device *peer;
41 struct net_device_stats *peerstats, *srcstats = &dev->stats;
42 struct sk_buff *skb;
43 unsigned int len;
44
45 if (can_dropped_invalid_skb(dev, oskb))
46 return NETDEV_TX_OK;
47
48 rcu_read_lock();
49 peer = rcu_dereference(priv->peer);
50 if (unlikely(!peer)) {
51 kfree_skb(oskb);
52 dev->stats.tx_dropped++;
53 goto out_unlock;
54 }
55
56 skb_tx_timestamp(oskb);
57
58 skb = skb_clone(oskb, GFP_ATOMIC);
59 if (skb) {
60 consume_skb(oskb);
61 } else {
62 kfree_skb(oskb);
63 goto out_unlock;
64 }
65
66 /* reset CAN GW hop counter */
67 skb->csum_start = 0;
68 skb->pkt_type = PACKET_BROADCAST;
69 skb->dev = peer;
70 skb->ip_summed = CHECKSUM_UNNECESSARY;
71
72 len = can_skb_get_data_len(skb);
73 if (netif_rx(skb) == NET_RX_SUCCESS) {
74 srcstats->tx_packets++;
75 srcstats->tx_bytes += len;
76 peerstats = &peer->stats;
77 peerstats->rx_packets++;
78 peerstats->rx_bytes += len;
79 }
80
81 out_unlock:
82 rcu_read_unlock();
83 return NETDEV_TX_OK;
84 }
85
86
vxcan_open(struct net_device * dev)87 static int vxcan_open(struct net_device *dev)
88 {
89 struct vxcan_priv *priv = netdev_priv(dev);
90 struct net_device *peer = rtnl_dereference(priv->peer);
91
92 if (!peer)
93 return -ENOTCONN;
94
95 if (peer->flags & IFF_UP) {
96 netif_carrier_on(dev);
97 netif_carrier_on(peer);
98 }
99 return 0;
100 }
101
vxcan_close(struct net_device * dev)102 static int vxcan_close(struct net_device *dev)
103 {
104 struct vxcan_priv *priv = netdev_priv(dev);
105 struct net_device *peer = rtnl_dereference(priv->peer);
106
107 netif_carrier_off(dev);
108 if (peer)
109 netif_carrier_off(peer);
110
111 return 0;
112 }
113
vxcan_get_iflink(const struct net_device * dev)114 static int vxcan_get_iflink(const struct net_device *dev)
115 {
116 struct vxcan_priv *priv = netdev_priv(dev);
117 struct net_device *peer;
118 int iflink;
119
120 rcu_read_lock();
121 peer = rcu_dereference(priv->peer);
122 iflink = peer ? READ_ONCE(peer->ifindex) : 0;
123 rcu_read_unlock();
124
125 return iflink;
126 }
127
vxcan_change_mtu(struct net_device * dev,int new_mtu)128 static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
129 {
130 /* Do not allow changing the MTU while running */
131 if (dev->flags & IFF_UP)
132 return -EBUSY;
133
134 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU &&
135 !can_is_canxl_dev_mtu(new_mtu))
136 return -EINVAL;
137
138 WRITE_ONCE(dev->mtu, new_mtu);
139 return 0;
140 }
141
142 static const struct net_device_ops vxcan_netdev_ops = {
143 .ndo_open = vxcan_open,
144 .ndo_stop = vxcan_close,
145 .ndo_start_xmit = vxcan_xmit,
146 .ndo_get_iflink = vxcan_get_iflink,
147 .ndo_change_mtu = vxcan_change_mtu,
148 };
149
150 static const struct ethtool_ops vxcan_ethtool_ops = {
151 .get_ts_info = ethtool_op_get_ts_info,
152 };
153
vxcan_setup(struct net_device * dev)154 static void vxcan_setup(struct net_device *dev)
155 {
156 struct can_ml_priv *can_ml;
157
158 dev->type = ARPHRD_CAN;
159 dev->mtu = CANFD_MTU;
160 dev->hard_header_len = 0;
161 dev->addr_len = 0;
162 dev->tx_queue_len = 0;
163 dev->flags = IFF_NOARP;
164 dev->netdev_ops = &vxcan_netdev_ops;
165 dev->ethtool_ops = &vxcan_ethtool_ops;
166 dev->needs_free_netdev = true;
167
168 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
169 can_set_ml_priv(dev, can_ml);
170 }
171
172 /* forward declaration for rtnl_create_link() */
173 static struct rtnl_link_ops vxcan_link_ops;
174
vxcan_newlink(struct net * net,struct net_device * dev,struct nlattr * tb[],struct nlattr * data[],struct netlink_ext_ack * extack)175 static int vxcan_newlink(struct net *net, struct net_device *dev,
176 struct nlattr *tb[], struct nlattr *data[],
177 struct netlink_ext_ack *extack)
178 {
179 struct vxcan_priv *priv;
180 struct net_device *peer;
181 struct net *peer_net;
182
183 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
184 char ifname[IFNAMSIZ];
185 unsigned char name_assign_type;
186 struct ifinfomsg *ifmp = NULL;
187 int err;
188
189 /* register peer device */
190 if (data && data[VXCAN_INFO_PEER]) {
191 struct nlattr *nla_peer;
192
193 nla_peer = data[VXCAN_INFO_PEER];
194 ifmp = nla_data(nla_peer);
195 err = rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack);
196 if (err < 0)
197 return err;
198
199 tbp = peer_tb;
200 }
201
202 if (ifmp && tbp[IFLA_IFNAME]) {
203 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
204 name_assign_type = NET_NAME_USER;
205 } else {
206 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
207 name_assign_type = NET_NAME_ENUM;
208 }
209
210 peer_net = rtnl_link_get_net(net, tbp);
211 if (IS_ERR(peer_net))
212 return PTR_ERR(peer_net);
213
214 peer = rtnl_create_link(peer_net, ifname, name_assign_type,
215 &vxcan_link_ops, tbp, extack);
216 if (IS_ERR(peer)) {
217 put_net(peer_net);
218 return PTR_ERR(peer);
219 }
220
221 if (ifmp && dev->ifindex)
222 peer->ifindex = ifmp->ifi_index;
223
224 err = register_netdevice(peer);
225 put_net(peer_net);
226 peer_net = NULL;
227 if (err < 0) {
228 free_netdev(peer);
229 return err;
230 }
231
232 netif_carrier_off(peer);
233
234 err = rtnl_configure_link(peer, ifmp, 0, NULL);
235 if (err < 0)
236 goto unregister_network_device;
237
238 /* register first device */
239 if (tb[IFLA_IFNAME])
240 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
241 else
242 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
243
244 err = register_netdevice(dev);
245 if (err < 0)
246 goto unregister_network_device;
247
248 netif_carrier_off(dev);
249
250 /* cross link the device pair */
251 priv = netdev_priv(dev);
252 rcu_assign_pointer(priv->peer, peer);
253
254 priv = netdev_priv(peer);
255 rcu_assign_pointer(priv->peer, dev);
256
257 return 0;
258
259 unregister_network_device:
260 unregister_netdevice(peer);
261 return err;
262 }
263
vxcan_dellink(struct net_device * dev,struct list_head * head)264 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
265 {
266 struct vxcan_priv *priv;
267 struct net_device *peer;
268
269 priv = netdev_priv(dev);
270 peer = rtnl_dereference(priv->peer);
271
272 /* Note : dellink() is called from default_device_exit_batch(),
273 * before a rcu_synchronize() point. The devices are guaranteed
274 * not being freed before one RCU grace period.
275 */
276 RCU_INIT_POINTER(priv->peer, NULL);
277 unregister_netdevice_queue(dev, head);
278
279 if (peer) {
280 priv = netdev_priv(peer);
281 RCU_INIT_POINTER(priv->peer, NULL);
282 unregister_netdevice_queue(peer, head);
283 }
284 }
285
286 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
287 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
288 };
289
vxcan_get_link_net(const struct net_device * dev)290 static struct net *vxcan_get_link_net(const struct net_device *dev)
291 {
292 struct vxcan_priv *priv = netdev_priv(dev);
293 struct net_device *peer = rtnl_dereference(priv->peer);
294
295 return peer ? dev_net(peer) : dev_net(dev);
296 }
297
298 static struct rtnl_link_ops vxcan_link_ops = {
299 .kind = DRV_NAME,
300 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv),
301 .setup = vxcan_setup,
302 .newlink = vxcan_newlink,
303 .dellink = vxcan_dellink,
304 .policy = vxcan_policy,
305 .maxtype = VXCAN_INFO_MAX,
306 .get_link_net = vxcan_get_link_net,
307 };
308
vxcan_init(void)309 static __init int vxcan_init(void)
310 {
311 pr_info("vxcan: Virtual CAN Tunnel driver\n");
312
313 return rtnl_link_register(&vxcan_link_ops);
314 }
315
vxcan_exit(void)316 static __exit void vxcan_exit(void)
317 {
318 rtnl_link_unregister(&vxcan_link_ops);
319 }
320
321 module_init(vxcan_init);
322 module_exit(vxcan_exit);
323