xref: /openbmc/linux/drivers/net/can/vxcan.c (revision f534f658)
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 ? 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 	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