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 27 MODULE_DESCRIPTION("Virtual CAN Tunnel"); 28 MODULE_LICENSE("GPL"); 29 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 30 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 31 32 struct vxcan_priv { 33 struct net_device __rcu *peer; 34 }; 35 36 static netdev_tx_t vxcan_xmit(struct sk_buff *oskb, 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 *)oskb->data; 41 struct net_device_stats *peerstats, *srcstats = &dev->stats; 42 struct sk_buff *skb; 43 u8 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 = skb_clone(oskb, GFP_ATOMIC); 57 if (skb) { 58 consume_skb(oskb); 59 } else { 60 kfree_skb(oskb); 61 goto out_unlock; 62 } 63 64 /* reset CAN GW hop counter */ 65 skb->csum_start = 0; 66 skb->pkt_type = PACKET_BROADCAST; 67 skb->dev = peer; 68 skb->ip_summed = CHECKSUM_UNNECESSARY; 69 70 len = cfd->can_id & CAN_RTR_FLAG ? 0 : cfd->len; 71 if (netif_rx(skb) == NET_RX_SUCCESS) { 72 srcstats->tx_packets++; 73 srcstats->tx_bytes += len; 74 peerstats = &peer->stats; 75 peerstats->rx_packets++; 76 peerstats->rx_bytes += len; 77 } 78 79 out_unlock: 80 rcu_read_unlock(); 81 return NETDEV_TX_OK; 82 } 83 84 85 static int vxcan_open(struct net_device *dev) 86 { 87 struct vxcan_priv *priv = netdev_priv(dev); 88 struct net_device *peer = rtnl_dereference(priv->peer); 89 90 if (!peer) 91 return -ENOTCONN; 92 93 if (peer->flags & IFF_UP) { 94 netif_carrier_on(dev); 95 netif_carrier_on(peer); 96 } 97 return 0; 98 } 99 100 static int vxcan_close(struct net_device *dev) 101 { 102 struct vxcan_priv *priv = netdev_priv(dev); 103 struct net_device *peer = rtnl_dereference(priv->peer); 104 105 netif_carrier_off(dev); 106 if (peer) 107 netif_carrier_off(peer); 108 109 return 0; 110 } 111 112 static int vxcan_get_iflink(const struct net_device *dev) 113 { 114 struct vxcan_priv *priv = netdev_priv(dev); 115 struct net_device *peer; 116 int iflink; 117 118 rcu_read_lock(); 119 peer = rcu_dereference(priv->peer); 120 iflink = peer ? peer->ifindex : 0; 121 rcu_read_unlock(); 122 123 return iflink; 124 } 125 126 static int vxcan_change_mtu(struct net_device *dev, int new_mtu) 127 { 128 /* Do not allow changing the MTU while running */ 129 if (dev->flags & IFF_UP) 130 return -EBUSY; 131 132 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 133 return -EINVAL; 134 135 dev->mtu = new_mtu; 136 return 0; 137 } 138 139 static const struct net_device_ops vxcan_netdev_ops = { 140 .ndo_open = vxcan_open, 141 .ndo_stop = vxcan_close, 142 .ndo_start_xmit = vxcan_xmit, 143 .ndo_get_iflink = vxcan_get_iflink, 144 .ndo_change_mtu = vxcan_change_mtu, 145 }; 146 147 static void vxcan_setup(struct net_device *dev) 148 { 149 struct can_ml_priv *can_ml; 150 151 dev->type = ARPHRD_CAN; 152 dev->mtu = CANFD_MTU; 153 dev->hard_header_len = 0; 154 dev->addr_len = 0; 155 dev->tx_queue_len = 0; 156 dev->flags = IFF_NOARP; 157 dev->netdev_ops = &vxcan_netdev_ops; 158 dev->needs_free_netdev = true; 159 160 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN); 161 can_set_ml_priv(dev, can_ml); 162 } 163 164 /* forward declaration for rtnl_create_link() */ 165 static struct rtnl_link_ops vxcan_link_ops; 166 167 static int vxcan_newlink(struct net *net, struct net_device *dev, 168 struct nlattr *tb[], struct nlattr *data[], 169 struct netlink_ext_ack *extack) 170 { 171 struct vxcan_priv *priv; 172 struct net_device *peer; 173 struct net *peer_net; 174 175 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb; 176 char ifname[IFNAMSIZ]; 177 unsigned char name_assign_type; 178 struct ifinfomsg *ifmp = NULL; 179 int err; 180 181 /* register peer device */ 182 if (data && data[VXCAN_INFO_PEER]) { 183 struct nlattr *nla_peer; 184 185 nla_peer = data[VXCAN_INFO_PEER]; 186 ifmp = nla_data(nla_peer); 187 err = rtnl_nla_parse_ifla(peer_tb, 188 nla_data(nla_peer) + 189 sizeof(struct ifinfomsg), 190 nla_len(nla_peer) - 191 sizeof(struct ifinfomsg), 192 NULL); 193 if (err < 0) 194 return err; 195 196 tbp = peer_tb; 197 } 198 199 if (ifmp && tbp[IFLA_IFNAME]) { 200 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 201 name_assign_type = NET_NAME_USER; 202 } else { 203 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 204 name_assign_type = NET_NAME_ENUM; 205 } 206 207 peer_net = rtnl_link_get_net(net, tbp); 208 if (IS_ERR(peer_net)) 209 return PTR_ERR(peer_net); 210 211 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 212 &vxcan_link_ops, tbp, extack); 213 if (IS_ERR(peer)) { 214 put_net(peer_net); 215 return PTR_ERR(peer); 216 } 217 218 if (ifmp && dev->ifindex) 219 peer->ifindex = ifmp->ifi_index; 220 221 err = register_netdevice(peer); 222 put_net(peer_net); 223 peer_net = NULL; 224 if (err < 0) { 225 free_netdev(peer); 226 return err; 227 } 228 229 netif_carrier_off(peer); 230 231 err = rtnl_configure_link(peer, ifmp); 232 if (err < 0) 233 goto unregister_network_device; 234 235 /* register first device */ 236 if (tb[IFLA_IFNAME]) 237 nla_strscpy(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 goto unregister_network_device; 244 245 netif_carrier_off(dev); 246 247 /* cross link the device pair */ 248 priv = netdev_priv(dev); 249 rcu_assign_pointer(priv->peer, peer); 250 251 priv = netdev_priv(peer); 252 rcu_assign_pointer(priv->peer, dev); 253 254 return 0; 255 256 unregister_network_device: 257 unregister_netdevice(peer); 258 return err; 259 } 260 261 static void vxcan_dellink(struct net_device *dev, struct list_head *head) 262 { 263 struct vxcan_priv *priv; 264 struct net_device *peer; 265 266 priv = netdev_priv(dev); 267 peer = rtnl_dereference(priv->peer); 268 269 /* Note : dellink() is called from default_device_exit_batch(), 270 * before a rcu_synchronize() point. The devices are guaranteed 271 * not being freed before one RCU grace period. 272 */ 273 RCU_INIT_POINTER(priv->peer, NULL); 274 unregister_netdevice_queue(dev, head); 275 276 if (peer) { 277 priv = netdev_priv(peer); 278 RCU_INIT_POINTER(priv->peer, NULL); 279 unregister_netdevice_queue(peer, head); 280 } 281 } 282 283 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 284 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 285 }; 286 287 static struct net *vxcan_get_link_net(const struct net_device *dev) 288 { 289 struct vxcan_priv *priv = netdev_priv(dev); 290 struct net_device *peer = rtnl_dereference(priv->peer); 291 292 return peer ? dev_net(peer) : dev_net(dev); 293 } 294 295 static struct rtnl_link_ops vxcan_link_ops = { 296 .kind = DRV_NAME, 297 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv), 298 .setup = vxcan_setup, 299 .newlink = vxcan_newlink, 300 .dellink = vxcan_dellink, 301 .policy = vxcan_policy, 302 .maxtype = VXCAN_INFO_MAX, 303 .get_link_net = vxcan_get_link_net, 304 }; 305 306 static __init int vxcan_init(void) 307 { 308 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 309 310 return rtnl_link_register(&vxcan_link_ops); 311 } 312 313 static __exit void vxcan_exit(void) 314 { 315 rtnl_link_unregister(&vxcan_link_ops); 316 } 317 318 module_init(vxcan_init); 319 module_exit(vxcan_exit); 320