[mirror_ubuntu-bionic-kernel.git] / drivers / net / can / vxcan.c

/*
 * vxcan.c - Virtual CAN Tunnel for cross namespace communication
 *
 * This code is derived from drivers/net/can/vcan.c for the virtual CAN
 * specific parts and from drivers/net/veth.c to implement the netlink API
 * for network interface pairs in a common and established way.
 *
 * Copyright (c) 2017 Oliver Hartkopp <socketcan@hartkopp.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
#include <linux/can/vxcan.h>
#include <linux/slab.h>
#include <net/rtnetlink.h>

#define DRV_NAME "vxcan"

MODULE_DESCRIPTION("Virtual CAN Tunnel");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
MODULE_ALIAS_RTNL_LINK(DRV_NAME);

struct vxcan_priv {
	struct net_device __rcu	*peer;
};

static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer;
	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
	struct net_device_stats *peerstats, *srcstats = &dev->stats;

	if (can_dropped_invalid_skb(dev, skb))
		return NETDEV_TX_OK;

	rcu_read_lock();
	peer = rcu_dereference(priv->peer);
	if (unlikely(!peer)) {
		kfree_skb(skb);
		dev->stats.tx_dropped++;
		goto out_unlock;
	}

	skb = can_create_echo_skb(skb);
	if (!skb)
		goto out_unlock;

	/* reset CAN GW hop counter */
	skb->csum_start = 0;
	skb->pkt_type   = PACKET_BROADCAST;
	skb->dev        = peer;
	skb->ip_summed  = CHECKSUM_UNNECESSARY;

	if (netif_rx_ni(skb) == NET_RX_SUCCESS) {
		srcstats->tx_packets++;
		srcstats->tx_bytes += cfd->len;
		peerstats = &peer->stats;
		peerstats->rx_packets++;
		peerstats->rx_bytes += cfd->len;
	}

out_unlock:
	rcu_read_unlock();
	return NETDEV_TX_OK;
}


static int vxcan_open(struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	if (!peer)
		return -ENOTCONN;

	if (peer->flags & IFF_UP) {
		netif_carrier_on(dev);
		netif_carrier_on(peer);
	}
	return 0;
}

static int vxcan_close(struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	netif_carrier_off(dev);
	if (peer)
		netif_carrier_off(peer);

	return 0;
}

static int vxcan_get_iflink(const struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer;
	int iflink;

	rcu_read_lock();
	peer = rcu_dereference(priv->peer);
	iflink = peer ? peer->ifindex : 0;
	rcu_read_unlock();

	return iflink;
}

static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
{
	/* Do not allow changing the MTU while running */
	if (dev->flags & IFF_UP)
		return -EBUSY;

	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
		return -EINVAL;

	dev->mtu = new_mtu;
	return 0;
}

static const struct net_device_ops vxcan_netdev_ops = {
	.ndo_open	= vxcan_open,
	.ndo_stop	= vxcan_close,
	.ndo_start_xmit	= vxcan_xmit,
	.ndo_get_iflink	= vxcan_get_iflink,
	.ndo_change_mtu = vxcan_change_mtu,
};

static void vxcan_setup(struct net_device *dev)
{
	dev->type		= ARPHRD_CAN;
	dev->mtu		= CANFD_MTU;
	dev->hard_header_len	= 0;
	dev->addr_len		= 0;
	dev->tx_queue_len	= 0;
	dev->flags		= (IFF_NOARP|IFF_ECHO);
	dev->netdev_ops		= &vxcan_netdev_ops;
	dev->needs_free_netdev	= true;
}

/* forward declaration for rtnl_create_link() */
static struct rtnl_link_ops vxcan_link_ops;

static int vxcan_newlink(struct net *net, struct net_device *dev,
			 struct nlattr *tb[], struct nlattr *data[],
			 struct netlink_ext_ack *extack)
{
	struct vxcan_priv *priv;
	struct net_device *peer;
	struct net *peer_net;

	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
	char ifname[IFNAMSIZ];
	unsigned char name_assign_type;
	struct ifinfomsg *ifmp = NULL;
	int err;

	/* register peer device */
	if (data && data[VXCAN_INFO_PEER]) {
		struct nlattr *nla_peer;

		nla_peer = data[VXCAN_INFO_PEER];
		ifmp = nla_data(nla_peer);
		err = rtnl_nla_parse_ifla(peer_tb,
					  nla_data(nla_peer) +
					  sizeof(struct ifinfomsg),
					  nla_len(nla_peer) -
					  sizeof(struct ifinfomsg),
					  NULL);
		if (err < 0)
			return err;

		tbp = peer_tb;
	}

	if (ifmp && tbp[IFLA_IFNAME]) {
		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
		name_assign_type = NET_NAME_USER;
	} else {
		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
		name_assign_type = NET_NAME_ENUM;
	}

	peer_net = rtnl_link_get_net(net, tbp);
	if (IS_ERR(peer_net))
		return PTR_ERR(peer_net);

	peer = rtnl_create_link(peer_net, ifname, name_assign_type,
				&vxcan_link_ops, tbp);
	if (IS_ERR(peer)) {
		put_net(peer_net);
		return PTR_ERR(peer);
	}

	if (ifmp && dev->ifindex)
		peer->ifindex = ifmp->ifi_index;

	err = register_netdevice(peer);
	put_net(peer_net);
	peer_net = NULL;
	if (err < 0) {
		free_netdev(peer);
		return err;
	}

	netif_carrier_off(peer);

	err = rtnl_configure_link(peer, ifmp);
	if (err < 0) {
		unregister_netdevice(peer);
		return err;
	}

	/* register first device */
	if (tb[IFLA_IFNAME])
		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
	else
		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");

	err = register_netdevice(dev);
	if (err < 0) {
		unregister_netdevice(peer);
		return err;
	}

	netif_carrier_off(dev);

	/* cross link the device pair */
	priv = netdev_priv(dev);
	rcu_assign_pointer(priv->peer, peer);

	priv = netdev_priv(peer);
	rcu_assign_pointer(priv->peer, dev);

	return 0;
}

static void vxcan_dellink(struct net_device *dev, struct list_head *head)
{
	struct vxcan_priv *priv;
	struct net_device *peer;

	priv = netdev_priv(dev);
	peer = rtnl_dereference(priv->peer);

	/* Note : dellink() is called from default_device_exit_batch(),
	 * before a rcu_synchronize() point. The devices are guaranteed
	 * not being freed before one RCU grace period.
	 */
	RCU_INIT_POINTER(priv->peer, NULL);
	unregister_netdevice_queue(dev, head);

	if (peer) {
		priv = netdev_priv(peer);
		RCU_INIT_POINTER(priv->peer, NULL);
		unregister_netdevice_queue(peer, head);
	}
}

static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
	[VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
};

static struct net *vxcan_get_link_net(const struct net_device *dev)
{
	struct vxcan_priv *priv = netdev_priv(dev);
	struct net_device *peer = rtnl_dereference(priv->peer);

	return peer ? dev_net(peer) : dev_net(dev);
}

static struct rtnl_link_ops vxcan_link_ops = {
	.kind		= DRV_NAME,
	.priv_size	= sizeof(struct vxcan_priv),
	.setup		= vxcan_setup,
	.newlink	= vxcan_newlink,
	.dellink	= vxcan_dellink,
	.policy		= vxcan_policy,
	.maxtype	= VXCAN_INFO_MAX,
	.get_link_net	= vxcan_get_link_net,
};

static __init int vxcan_init(void)
{
	pr_info("vxcan: Virtual CAN Tunnel driver\n");

	return rtnl_link_register(&vxcan_link_ops);
}

static __exit void vxcan_exit(void)
{
	rtnl_link_unregister(&vxcan_link_ops);
}

module_init(vxcan_init);
module_exit(vxcan_exit);
Commit	Line	Data
a8f820a3 OH	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
	37	MODULE_DESCRIPTION("Virtual CAN Tunnel");
	38	MODULE_LICENSE("GPL");
	39	MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
	40	MODULE_ALIAS_RTNL_LINK(DRV_NAME);
	41
	42	struct vxcan_priv {
	43	struct net_device __rcu *peer;
	44	};
	45
	46	static 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
82	out_unlock:
83	rcu_read_unlock();
84	return NETDEV_TX_OK;
85	}
86
87
88	static 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
103	static 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
115	static 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
129	static 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
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 void vxcan_setup(struct net_device *dev)
151	{
152	dev->type = ARPHRD_CAN;
97edec3a	153	dev->mtu = CANFD_MTU;
a8f820a3 OH	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;
cf124db5	159	dev->needs_free_netdev = true;
a8f820a3 OH	160	}
	161
	162	/* forward declaration for rtnl_create_link() */
	163	static struct rtnl_link_ops vxcan_link_ops;
	164
	165	static int vxcan_newlink(struct net net, struct net_device dev,
7a3f4a18 MS	166	struct nlattr tb[], struct nlattr data[],
7a3f4a18 MS	167	struct netlink_ext_ack *extack)
a8f820a3 OH	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
b4c2951a	197	if (ifmp && tbp[IFLA_IFNAME]) {
a8f820a3 OH	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	unregister_netdevice(peer);
	232	return err;
	233	}
	234
	235	/* register first device */
	236	if (tb[IFLA_IFNAME])
	237	nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
	238	else
	239	snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
	240
	241	err = register_netdevice(dev);
	242	if (err < 0) {
	243	unregister_netdevice(peer);
	244	return err;
	245	}
	246
	247	netif_carrier_off(dev);
	248
	249	/* cross link the device pair */
	250	priv = netdev_priv(dev);
	251	rcu_assign_pointer(priv->peer, peer);
	252
	253	priv = netdev_priv(peer);
	254	rcu_assign_pointer(priv->peer, dev);
	255
	256	return 0;
	257	}
	258
	259	static 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
281	static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
282	[VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
283	};
284
285	static 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
293	static 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
304	static __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
311	static __exit void vxcan_exit(void)
312	{
313	rtnl_link_unregister(&vxcan_link_ops);
314	}
315
316	module_init(vxcan_init);
317	module_exit(vxcan_exit);