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 * peer_net,struct net_device * dev,struct nlattr * tb[],struct nlattr * data[],struct netlink_ext_ack * extack)175 static int vxcan_newlink(struct net *peer_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
182 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
183 char ifname[IFNAMSIZ];
184 unsigned char name_assign_type;
185 struct ifinfomsg *ifmp = NULL;
186 int err;
187
188 /* register peer device */
189 if (data && data[VXCAN_INFO_PEER]) {
190 struct nlattr *nla_peer = data[VXCAN_INFO_PEER];
191
192 ifmp = nla_data(nla_peer);
193 rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack);
194 tbp = peer_tb;
195 }
196
197 if (ifmp && tbp[IFLA_IFNAME]) {
198 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
199 name_assign_type = NET_NAME_USER;
200 } else {
201 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
202 name_assign_type = NET_NAME_ENUM;
203 }
204
205 peer = rtnl_create_link(peer_net, ifname, name_assign_type,
206 &vxcan_link_ops, tbp, extack);
207 if (IS_ERR(peer))
208 return PTR_ERR(peer);
209
210 if (ifmp && dev->ifindex)
211 peer->ifindex = ifmp->ifi_index;
212
213 err = register_netdevice(peer);
214 if (err < 0) {
215 free_netdev(peer);
216 return err;
217 }
218
219 netif_carrier_off(peer);
220
221 err = rtnl_configure_link(peer, ifmp, 0, NULL);
222 if (err < 0)
223 goto unregister_network_device;
224
225 /* register first device */
226 if (tb[IFLA_IFNAME])
227 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
228 else
229 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
230
231 err = register_netdevice(dev);
232 if (err < 0)
233 goto unregister_network_device;
234
235 netif_carrier_off(dev);
236
237 /* cross link the device pair */
238 priv = netdev_priv(dev);
239 rcu_assign_pointer(priv->peer, peer);
240
241 priv = netdev_priv(peer);
242 rcu_assign_pointer(priv->peer, dev);
243
244 return 0;
245
246 unregister_network_device:
247 unregister_netdevice(peer);
248 return err;
249 }
250
vxcan_dellink(struct net_device * dev,struct list_head * head)251 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
252 {
253 struct vxcan_priv *priv;
254 struct net_device *peer;
255
256 priv = netdev_priv(dev);
257 peer = rtnl_dereference(priv->peer);
258
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.
262 */
263 RCU_INIT_POINTER(priv->peer, NULL);
264 unregister_netdevice_queue(dev, head);
265
266 if (peer) {
267 priv = netdev_priv(peer);
268 RCU_INIT_POINTER(priv->peer, NULL);
269 unregister_netdevice_queue(peer, head);
270 }
271 }
272
273 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
274 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
275 };
276
vxcan_get_link_net(const struct net_device * dev)277 static struct net *vxcan_get_link_net(const struct net_device *dev)
278 {
279 struct vxcan_priv *priv = netdev_priv(dev);
280 struct net_device *peer = rtnl_dereference(priv->peer);
281
282 return peer ? dev_net(peer) : dev_net(dev);
283 }
284
285 static struct rtnl_link_ops vxcan_link_ops = {
286 .kind = DRV_NAME,
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 .peer_type = VXCAN_INFO_PEER,
293 .maxtype = VXCAN_INFO_MAX,
294 .get_link_net = vxcan_get_link_net,
295 };
296
vxcan_init(void)297 static __init int vxcan_init(void)
298 {
299 pr_info("vxcan: Virtual CAN Tunnel driver\n");
300
301 return rtnl_link_register(&vxcan_link_ops);
302 }
303
vxcan_exit(void)304 static __exit void vxcan_exit(void)
305 {
306 rtnl_link_unregister(&vxcan_link_ops);
307 }
308
309 module_init(vxcan_init);
310 module_exit(vxcan_exit);
311