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 u8 len; 43 44 if (can_dropped_invalid_skb(dev, skb)) 45 return NETDEV_TX_OK; 46 47 rcu_read_lock(); 48 peer = rcu_dereference(priv->peer); 49 if (unlikely(!peer)) { 50 kfree_skb(skb); 51 dev->stats.tx_dropped++; 52 goto out_unlock; 53 } 54 55 skb = can_create_echo_skb(skb); 56 if (!skb) 57 goto out_unlock; 58 59 /* reset CAN GW hop counter */ 60 skb->csum_start = 0; 61 skb->pkt_type = PACKET_BROADCAST; 62 skb->dev = peer; 63 skb->ip_summed = CHECKSUM_UNNECESSARY; 64 65 len = cfd->len; 66 if (netif_rx_ni(skb) == NET_RX_SUCCESS) { 67 srcstats->tx_packets++; 68 srcstats->tx_bytes += len; 69 peerstats = &peer->stats; 70 peerstats->rx_packets++; 71 peerstats->rx_bytes += len; 72 } 73 74out_unlock: 75 rcu_read_unlock(); 76 return NETDEV_TX_OK; 77} 78 79 80static int vxcan_open(struct net_device *dev) 81{ 82 struct vxcan_priv *priv = netdev_priv(dev); 83 struct net_device *peer = rtnl_dereference(priv->peer); 84 85 if (!peer) 86 return -ENOTCONN; 87 88 if (peer->flags & IFF_UP) { 89 netif_carrier_on(dev); 90 netif_carrier_on(peer); 91 } 92 return 0; 93} 94 95static int vxcan_close(struct net_device *dev) 96{ 97 struct vxcan_priv *priv = netdev_priv(dev); 98 struct net_device *peer = rtnl_dereference(priv->peer); 99 100 netif_carrier_off(dev); 101 if (peer) 102 netif_carrier_off(peer); 103 104 return 0; 105} 106 107static int vxcan_get_iflink(const struct net_device *dev) 108{ 109 struct vxcan_priv *priv = netdev_priv(dev); 110 struct net_device *peer; 111 int iflink; 112 113 rcu_read_lock(); 114 peer = rcu_dereference(priv->peer); 115 iflink = peer ? peer->ifindex : 0; 116 rcu_read_unlock(); 117 118 return iflink; 119} 120 121static int vxcan_change_mtu(struct net_device *dev, int new_mtu) 122{ 123 /* Do not allow changing the MTU while running */ 124 if (dev->flags & IFF_UP) 125 return -EBUSY; 126 127 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 128 return -EINVAL; 129 130 dev->mtu = new_mtu; 131 return 0; 132} 133 134static const struct net_device_ops vxcan_netdev_ops = { 135 .ndo_open = vxcan_open, 136 .ndo_stop = vxcan_close, 137 .ndo_start_xmit = vxcan_xmit, 138 .ndo_get_iflink = vxcan_get_iflink, 139 .ndo_change_mtu = vxcan_change_mtu, 140}; 141 142static void vxcan_setup(struct net_device *dev) 143{ 144 struct can_ml_priv *can_ml; 145 146 dev->type = ARPHRD_CAN; 147 dev->mtu = CANFD_MTU; 148 dev->hard_header_len = 0; 149 dev->addr_len = 0; 150 dev->tx_queue_len = 0; 151 dev->flags = IFF_NOARP; 152 dev->netdev_ops = &vxcan_netdev_ops; 153 dev->needs_free_netdev = true; 154 155 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN); 156 can_set_ml_priv(dev, can_ml); 157} 158 159/* forward declaration for rtnl_create_link() */ 160static struct rtnl_link_ops vxcan_link_ops; 161 162static int vxcan_newlink(struct net *net, struct net_device *dev, 163 struct nlattr *tb[], struct nlattr *data[], 164 struct netlink_ext_ack *extack) 165{ 166 struct vxcan_priv *priv; 167 struct net_device *peer; 168 struct net *peer_net; 169 170 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb; 171 char ifname[IFNAMSIZ]; 172 unsigned char name_assign_type; 173 struct ifinfomsg *ifmp = NULL; 174 int err; 175 176 /* register peer device */ 177 if (data && data[VXCAN_INFO_PEER]) { 178 struct nlattr *nla_peer; 179 180 nla_peer = data[VXCAN_INFO_PEER]; 181 ifmp = nla_data(nla_peer); 182 err = rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack); 183 if (err < 0) 184 return err; 185 186 tbp = peer_tb; 187 } 188 189 if (ifmp && tbp[IFLA_IFNAME]) { 190 nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 191 name_assign_type = NET_NAME_USER; 192 } else { 193 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 194 name_assign_type = NET_NAME_ENUM; 195 } 196 197 peer_net = rtnl_link_get_net(net, tbp); 198 if (IS_ERR(peer_net)) 199 return PTR_ERR(peer_net); 200 201 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 202 &vxcan_link_ops, tbp, extack); 203 if (IS_ERR(peer)) { 204 put_net(peer_net); 205 return PTR_ERR(peer); 206 } 207 208 if (ifmp && dev->ifindex) 209 peer->ifindex = ifmp->ifi_index; 210 211 err = register_netdevice(peer); 212 put_net(peer_net); 213 peer_net = NULL; 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); 222 if (err < 0) 223 goto unregister_network_device; 224 225 /* register first device */ 226 if (tb[IFLA_IFNAME]) 227 nla_strlcpy(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 246unregister_network_device: 247 unregister_netdevice(peer); 248 return err; 249} 250 251static 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 273static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 274 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 275}; 276 277static 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 285static 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 .maxtype = VXCAN_INFO_MAX, 293 .get_link_net = vxcan_get_link_net, 294}; 295 296static __init int vxcan_init(void) 297{ 298 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 299 300 return rtnl_link_register(&vxcan_link_ops); 301} 302 303static __exit void vxcan_exit(void) 304{ 305 rtnl_link_unregister(&vxcan_link_ops); 306} 307 308module_init(vxcan_init); 309module_exit(vxcan_exit); 310