can: add Virtual CAN Tunnel driver (vxcan) (a8f820a3) · Commits · e / devices / android_kernel_oneplus_sm7250

drivers/net/can/Kconfig

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		@@ -9,6 +9,24 @@ config CAN_VCAN
		This driver can also be built as a module. If so, the module
		will be called vcan.

		config CAN_VXCAN
		tristate "Virtual CAN Tunnel (vxcan)"
		---help---
		Similar to the virtual ethernet driver veth, vxcan implements a
		local CAN traffic tunnel between two virtual CAN network devices.
		When creating a vxcan, two vxcan devices are created as pair.
		When one end receives the packet it appears on its pair and vice
		versa. The vxcan can be used for cross namespace communication.

		In opposite to vcan loopback devices the vxcan only forwards CAN
		frames to its pair and does not provide a local echo of sent
		CAN frames. To disable a potential echo in af_can.c the vxcan driver
		announces IFF_ECHO in the interface flags. To have a clean start
		in each namespace the CAN GW hop counter is set to zero.

		This driver can also be built as a module. If so, the module
		will be called vxcan.

		config CAN_SLCAN
		tristate "Serial / USB serial CAN Adaptors (slcan)"
		depends on TTY

drivers/net/can/Makefile

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		@@ -3,6 +3,7 @@
		#

		obj-$(CONFIG_CAN_VCAN) += vcan.o
		obj-$(CONFIG_CAN_VXCAN) += vxcan.o
		obj-$(CONFIG_CAN_SLCAN) += slcan.o

		obj-$(CONFIG_CAN_DEV) += can-dev.o

drivers/net/can/vxcan.c

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		/*
		* 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 = CAN_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->destructor = free_netdev;
		}

		/* 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 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 (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);

include/uapi/linux/can/vxcan.h

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		#ifndef _UAPI_CAN_VXCAN_H
		#define _UAPI_CAN_VXCAN_H

		enum {
		VXCAN_INFO_UNSPEC,
		VXCAN_INFO_PEER,

		__VXCAN_INFO_MAX
		#define VXCAN_INFO_MAX (__VXCAN_INFO_MAX - 1)
		};

		#endif