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 *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->can_id & CAN_RTR_FLAG ? 0 : 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 74 out_unlock: 75 rcu_read_unlock(); 76 return NETDEV_TX_OK; 77 } 78 79 80 static 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 95 static 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 } 106 107 static 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 } 120 121 static 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 } 133 134 static 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 }; 141 142 static 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|IFF_ECHO); 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() */ 160 static struct rtnl_link_ops vxcan_link_ops; 161 162 static 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_ifla(peer_tb, 183 nla_data(nla_peer) + 184 sizeof(struct ifinfomsg), 185 nla_len(nla_peer) - 186 sizeof(struct ifinfomsg), 187 NULL); 188 if (err < 0) 189 return err; 190 191 tbp = peer_tb; 192 } 193 194 if (ifmp && tbp[IFLA_IFNAME]) { 195 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 196 name_assign_type = NET_NAME_USER; 197 } else { 198 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 199 name_assign_type = NET_NAME_ENUM; 200 } 201 202 peer_net = rtnl_link_get_net(net, tbp); 203 if (IS_ERR(peer_net)) 204 return PTR_ERR(peer_net); 205 206 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 207 &vxcan_link_ops, tbp, extack); 208 if (IS_ERR(peer)) { 209 put_net(peer_net); 210 return PTR_ERR(peer); 211 } 212 213 if (ifmp && dev->ifindex) 214 peer->ifindex = ifmp->ifi_index; 215 216 err = register_netdevice(peer); 217 put_net(peer_net); 218 peer_net = NULL; 219 if (err < 0) { 220 free_netdev(peer); 221 return err; 222 } 223 224 netif_carrier_off(peer); 225 226 err = rtnl_configure_link(peer, ifmp); 227 if (err < 0) 228 goto unregister_network_device; 229 230 /* register first device */ 231 if (tb[IFLA_IFNAME]) 232 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ); 233 else 234 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d"); 235 236 err = register_netdevice(dev); 237 if (err < 0) 238 goto unregister_network_device; 239 240 netif_carrier_off(dev); 241 242 /* cross link the device pair */ 243 priv = netdev_priv(dev); 244 rcu_assign_pointer(priv->peer, peer); 245 246 priv = netdev_priv(peer); 247 rcu_assign_pointer(priv->peer, dev); 248 249 return 0; 250 251 unregister_network_device: 252 unregister_netdevice(peer); 253 return err; 254 } 255 256 static void vxcan_dellink(struct net_device *dev, struct list_head *head) 257 { 258 struct vxcan_priv *priv; 259 struct net_device *peer; 260 261 priv = netdev_priv(dev); 262 peer = rtnl_dereference(priv->peer); 263 264 /* Note : dellink() is called from default_device_exit_batch(), 265 * before a rcu_synchronize() point. The devices are guaranteed 266 * not being freed before one RCU grace period. 267 */ 268 RCU_INIT_POINTER(priv->peer, NULL); 269 unregister_netdevice_queue(dev, head); 270 271 if (peer) { 272 priv = netdev_priv(peer); 273 RCU_INIT_POINTER(priv->peer, NULL); 274 unregister_netdevice_queue(peer, head); 275 } 276 } 277 278 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 279 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 280 }; 281 282 static struct net *vxcan_get_link_net(const struct net_device *dev) 283 { 284 struct vxcan_priv *priv = netdev_priv(dev); 285 struct net_device *peer = rtnl_dereference(priv->peer); 286 287 return peer ? dev_net(peer) : dev_net(dev); 288 } 289 290 static struct rtnl_link_ops vxcan_link_ops = { 291 .kind = DRV_NAME, 292 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv), 293 .setup = vxcan_setup, 294 .newlink = vxcan_newlink, 295 .dellink = vxcan_dellink, 296 .policy = vxcan_policy, 297 .maxtype = VXCAN_INFO_MAX, 298 .get_link_net = vxcan_get_link_net, 299 }; 300 301 static __init int vxcan_init(void) 302 { 303 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 304 305 return rtnl_link_register(&vxcan_link_ops); 306 } 307 308 static __exit void vxcan_exit(void) 309 { 310 rtnl_link_unregister(&vxcan_link_ops); 311 } 312 313 module_init(vxcan_init); 314 module_exit(vxcan_exit); 315