1/*
  2 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
  3 *
  4 * This code is derived from drivers/net/can/vcan.c for the virtual CAN
  5 * specific parts and from drivers/net/veth.c to implement the netlink API
  6 * for network interface pairs in a common and established way.
  7 *
  8 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
  9 *
 10 * This program is free software; you can redistribute it and/or modify
 11 * it under the terms of the version 2 of the GNU General Public License
 12 * as published by the Free Software Foundation
 13 *
 14 * This program is distributed in the hope that it will be useful,
 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 17 * GNU General Public License for more details.
 18 *
 19 * You should have received a copy of the GNU General Public License
 20 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 21 */
 22
 23#include <linux/module.h>
 24#include <linux/init.h>
 25#include <linux/netdevice.h>
 26#include <linux/if_arp.h>
 27#include <linux/if_ether.h>
 28#include <linux/can.h>
 29#include <linux/can/dev.h>
 30#include <linux/can/skb.h>
 31#include <linux/can/vxcan.h>
 
 32#include <linux/slab.h>
 33#include <net/rtnetlink.h>
 34
 35#define DRV_NAME "vxcan"
 36
 37MODULE_DESCRIPTION("Virtual CAN Tunnel");
 38MODULE_LICENSE("GPL");
 39MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
 40MODULE_ALIAS_RTNL_LINK(DRV_NAME);
 41
 42struct vxcan_priv {
 43	struct net_device __rcu	*peer;
 44};
 45
 46static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev)
 47{
 48	struct vxcan_priv *priv = netdev_priv(dev);
 49	struct net_device *peer;
 50	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 51	struct net_device_stats *peerstats, *srcstats = &dev->stats;
 52
 53	if (can_dropped_invalid_skb(dev, skb))
 54		return NETDEV_TX_OK;
 55
 56	rcu_read_lock();
 57	peer = rcu_dereference(priv->peer);
 58	if (unlikely(!peer)) {
 59		kfree_skb(skb);
 60		dev->stats.tx_dropped++;
 61		goto out_unlock;
 62	}
 63
 64	skb = can_create_echo_skb(skb);
 65	if (!skb)
 66		goto out_unlock;
 67
 68	/* reset CAN GW hop counter */
 69	skb->csum_start = 0;
 70	skb->pkt_type   = PACKET_BROADCAST;
 71	skb->dev        = peer;
 72	skb->ip_summed  = CHECKSUM_UNNECESSARY;
 73
 74	if (netif_rx_ni(skb) == NET_RX_SUCCESS) {
 75		srcstats->tx_packets++;
 76		srcstats->tx_bytes += cfd->len;
 77		peerstats = &peer->stats;
 78		peerstats->rx_packets++;
 79		peerstats->rx_bytes += cfd->len;
 80	}
 81
 82out_unlock:
 83	rcu_read_unlock();
 84	return NETDEV_TX_OK;
 85}
 86
 87
 88static int vxcan_open(struct net_device *dev)
 89{
 90	struct vxcan_priv *priv = netdev_priv(dev);
 91	struct net_device *peer = rtnl_dereference(priv->peer);
 92
 93	if (!peer)
 94		return -ENOTCONN;
 95
 96	if (peer->flags & IFF_UP) {
 97		netif_carrier_on(dev);
 98		netif_carrier_on(peer);
 99	}
100	return 0;
101}
102
103static int vxcan_close(struct net_device *dev)
104{
105	struct vxcan_priv *priv = netdev_priv(dev);
106	struct net_device *peer = rtnl_dereference(priv->peer);
107
108	netif_carrier_off(dev);
109	if (peer)
110		netif_carrier_off(peer);
111
112	return 0;
113}
114
115static int vxcan_get_iflink(const struct net_device *dev)
116{
117	struct vxcan_priv *priv = netdev_priv(dev);
118	struct net_device *peer;
119	int iflink;
120
121	rcu_read_lock();
122	peer = rcu_dereference(priv->peer);
123	iflink = peer ? peer->ifindex : 0;
124	rcu_read_unlock();
125
126	return iflink;
127}
128
129static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
130{
131	/* Do not allow changing the MTU while running */
132	if (dev->flags & IFF_UP)
133		return -EBUSY;
134
135	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
136		return -EINVAL;
137
138	dev->mtu = new_mtu;
139	return 0;
140}
141
142static 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
150static void vxcan_setup(struct net_device *dev)
151{
152	dev->type		= ARPHRD_CAN;
153	dev->mtu		= CANFD_MTU;
154	dev->hard_header_len	= 0;
155	dev->addr_len		= 0;
156	dev->tx_queue_len	= 0;
157	dev->flags		= (IFF_NOARP|IFF_ECHO);
158	dev->netdev_ops		= &vxcan_netdev_ops;
159	dev->needs_free_netdev	= true;
 
160}
161
162/* forward declaration for rtnl_create_link() */
163static struct rtnl_link_ops vxcan_link_ops;
164
165static int vxcan_newlink(struct net *net, struct net_device *dev,
166			 struct nlattr *tb[], struct nlattr *data[],
167			 struct netlink_ext_ack *extack)
168{
169	struct vxcan_priv *priv;
170	struct net_device *peer;
171	struct net *peer_net;
172
173	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
174	char ifname[IFNAMSIZ];
175	unsigned char name_assign_type;
176	struct ifinfomsg *ifmp = NULL;
177	int err;
178
179	/* register peer device */
180	if (data && data[VXCAN_INFO_PEER]) {
181		struct nlattr *nla_peer;
182
183		nla_peer = data[VXCAN_INFO_PEER];
184		ifmp = nla_data(nla_peer);
185		err = rtnl_nla_parse_ifla(peer_tb,
186					  nla_data(nla_peer) +
187					  sizeof(struct ifinfomsg),
188					  nla_len(nla_peer) -
189					  sizeof(struct ifinfomsg),
190					  NULL);
191		if (err < 0)
192			return err;
193
194		tbp = peer_tb;
195	}
196
197	if (ifmp && tbp[IFLA_IFNAME]) {
198		nla_strlcpy(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_net = rtnl_link_get_net(net, tbp);
206	if (IS_ERR(peer_net))
207		return PTR_ERR(peer_net);
208
209	peer = rtnl_create_link(peer_net, ifname, name_assign_type,
210				&vxcan_link_ops, tbp);
211	if (IS_ERR(peer)) {
212		put_net(peer_net);
213		return PTR_ERR(peer);
214	}
215
216	if (ifmp && dev->ifindex)
217		peer->ifindex = ifmp->ifi_index;
218
219	err = register_netdevice(peer);
220	put_net(peer_net);
221	peer_net = NULL;
222	if (err < 0) {
223		free_netdev(peer);
224		return err;
225	}
226
227	netif_carrier_off(peer);
228
229	err = rtnl_configure_link(peer, ifmp);
230	if (err < 0)
231		goto unregister_network_device;
232
233	/* register first device */
234	if (tb[IFLA_IFNAME])
235		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
236	else
237		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
238
239	err = register_netdevice(dev);
240	if (err < 0)
241		goto unregister_network_device;
242
243	netif_carrier_off(dev);
244
245	/* cross link the device pair */
246	priv = netdev_priv(dev);
247	rcu_assign_pointer(priv->peer, peer);
248
249	priv = netdev_priv(peer);
250	rcu_assign_pointer(priv->peer, dev);
251
252	return 0;
253
254unregister_network_device:
255	unregister_netdevice(peer);
256	return err;
257}
258
259static void vxcan_dellink(struct net_device *dev, struct list_head *head)
260{
261	struct vxcan_priv *priv;
262	struct net_device *peer;
263
264	priv = netdev_priv(dev);
265	peer = rtnl_dereference(priv->peer);
266
267	/* Note : dellink() is called from default_device_exit_batch(),
268	 * before a rcu_synchronize() point. The devices are guaranteed
269	 * not being freed before one RCU grace period.
270	 */
271	RCU_INIT_POINTER(priv->peer, NULL);
272	unregister_netdevice_queue(dev, head);
273
274	if (peer) {
275		priv = netdev_priv(peer);
276		RCU_INIT_POINTER(priv->peer, NULL);
277		unregister_netdevice_queue(peer, head);
278	}
279}
280
281static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
282	[VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
283};
284
285static struct net *vxcan_get_link_net(const struct net_device *dev)
286{
287	struct vxcan_priv *priv = netdev_priv(dev);
288	struct net_device *peer = rtnl_dereference(priv->peer);
289
290	return peer ? dev_net(peer) : dev_net(dev);
291}
292
293static struct rtnl_link_ops vxcan_link_ops = {
294	.kind		= DRV_NAME,
295	.priv_size	= sizeof(struct vxcan_priv),
296	.setup		= vxcan_setup,
297	.newlink	= vxcan_newlink,
298	.dellink	= vxcan_dellink,
299	.policy		= vxcan_policy,
300	.maxtype	= VXCAN_INFO_MAX,
301	.get_link_net	= vxcan_get_link_net,
302};
303
304static __init int vxcan_init(void)
305{
306	pr_info("vxcan: Virtual CAN Tunnel driver\n");
307
308	return rtnl_link_register(&vxcan_link_ops);
309}
310
311static __exit void vxcan_exit(void)
312{
313	rtnl_link_unregister(&vxcan_link_ops);
314}
315
316module_init(vxcan_init);
317module_exit(vxcan_exit);

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