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 43 if (can_dropped_invalid_skb(dev, skb)) 44 return NETDEV_TX_OK; 45 46 rcu_read_lock(); 47 peer = rcu_dereference(priv->peer); 48 if (unlikely(!peer)) { 49 kfree_skb(skb); 50 dev->stats.tx_dropped++; 51 goto out_unlock; 52 } 53 54 skb = can_create_echo_skb(skb); 55 if (!skb) 56 goto out_unlock; 57 58 /* reset CAN GW hop counter */ 59 skb->csum_start = 0; 60 skb->pkt_type = PACKET_BROADCAST; 61 skb->dev = peer; 62 skb->ip_summed = CHECKSUM_UNNECESSARY; 63 64 if (netif_rx_ni(skb) == NET_RX_SUCCESS) { 65 srcstats->tx_packets++; 66 srcstats->tx_bytes += cfd->len; 67 peerstats = &peer->stats; 68 peerstats->rx_packets++; 69 peerstats->rx_bytes += cfd->len; 70 } 71 72 out_unlock: 73 rcu_read_unlock(); 74 return NETDEV_TX_OK; 75 } 76 77 78 static int vxcan_open(struct net_device *dev) 79 { 80 struct vxcan_priv *priv = netdev_priv(dev); 81 struct net_device *peer = rtnl_dereference(priv->peer); 82 83 if (!peer) 84 return -ENOTCONN; 85 86 if (peer->flags & IFF_UP) { 87 netif_carrier_on(dev); 88 netif_carrier_on(peer); 89 } 90 return 0; 91 } 92 93 static int vxcan_close(struct net_device *dev) 94 { 95 struct vxcan_priv *priv = netdev_priv(dev); 96 struct net_device *peer = rtnl_dereference(priv->peer); 97 98 netif_carrier_off(dev); 99 if (peer) 100 netif_carrier_off(peer); 101 102 return 0; 103 } 104 105 static int vxcan_get_iflink(const struct net_device *dev) 106 { 107 struct vxcan_priv *priv = netdev_priv(dev); 108 struct net_device *peer; 109 int iflink; 110 111 rcu_read_lock(); 112 peer = rcu_dereference(priv->peer); 113 iflink = peer ? peer->ifindex : 0; 114 rcu_read_unlock(); 115 116 return iflink; 117 } 118 119 static int vxcan_change_mtu(struct net_device *dev, int new_mtu) 120 { 121 /* Do not allow changing the MTU while running */ 122 if (dev->flags & IFF_UP) 123 return -EBUSY; 124 125 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 126 return -EINVAL; 127 128 dev->mtu = new_mtu; 129 return 0; 130 } 131 132 static const struct net_device_ops vxcan_netdev_ops = { 133 .ndo_open = vxcan_open, 134 .ndo_stop = vxcan_close, 135 .ndo_start_xmit = vxcan_xmit, 136 .ndo_get_iflink = vxcan_get_iflink, 137 .ndo_change_mtu = vxcan_change_mtu, 138 }; 139 140 static void vxcan_setup(struct net_device *dev) 141 { 142 dev->type = ARPHRD_CAN; 143 dev->mtu = CANFD_MTU; 144 dev->hard_header_len = 0; 145 dev->addr_len = 0; 146 dev->tx_queue_len = 0; 147 dev->flags = (IFF_NOARP|IFF_ECHO); 148 dev->netdev_ops = &vxcan_netdev_ops; 149 dev->needs_free_netdev = true; 150 dev->ml_priv = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN); 151 } 152 153 /* forward declaration for rtnl_create_link() */ 154 static struct rtnl_link_ops vxcan_link_ops; 155 156 static int vxcan_newlink(struct net *net, struct net_device *dev, 157 struct nlattr *tb[], struct nlattr *data[], 158 struct netlink_ext_ack *extack) 159 { 160 struct vxcan_priv *priv; 161 struct net_device *peer; 162 struct net *peer_net; 163 164 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb; 165 char ifname[IFNAMSIZ]; 166 unsigned char name_assign_type; 167 struct ifinfomsg *ifmp = NULL; 168 int err; 169 170 /* register peer device */ 171 if (data && data[VXCAN_INFO_PEER]) { 172 struct nlattr *nla_peer; 173 174 nla_peer = data[VXCAN_INFO_PEER]; 175 ifmp = nla_data(nla_peer); 176 err = rtnl_nla_parse_ifla(peer_tb, 177 nla_data(nla_peer) + 178 sizeof(struct ifinfomsg), 179 nla_len(nla_peer) - 180 sizeof(struct ifinfomsg), 181 NULL); 182 if (err < 0) 183 return err; 184 185 tbp = peer_tb; 186 } 187 188 if (ifmp && tbp[IFLA_IFNAME]) { 189 nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 190 name_assign_type = NET_NAME_USER; 191 } else { 192 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 193 name_assign_type = NET_NAME_ENUM; 194 } 195 196 peer_net = rtnl_link_get_net(net, tbp); 197 if (IS_ERR(peer_net)) 198 return PTR_ERR(peer_net); 199 200 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 201 &vxcan_link_ops, tbp, extack); 202 if (IS_ERR(peer)) { 203 put_net(peer_net); 204 return PTR_ERR(peer); 205 } 206 207 if (ifmp && dev->ifindex) 208 peer->ifindex = ifmp->ifi_index; 209 210 err = register_netdevice(peer); 211 put_net(peer_net); 212 peer_net = NULL; 213 if (err < 0) { 214 free_netdev(peer); 215 return err; 216 } 217 218 netif_carrier_off(peer); 219 220 err = rtnl_configure_link(peer, ifmp); 221 if (err < 0) 222 goto unregister_network_device; 223 224 /* register first device */ 225 if (tb[IFLA_IFNAME]) 226 nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ); 227 else 228 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d"); 229 230 err = register_netdevice(dev); 231 if (err < 0) 232 goto unregister_network_device; 233 234 netif_carrier_off(dev); 235 236 /* cross link the device pair */ 237 priv = netdev_priv(dev); 238 rcu_assign_pointer(priv->peer, peer); 239 240 priv = netdev_priv(peer); 241 rcu_assign_pointer(priv->peer, dev); 242 243 return 0; 244 245 unregister_network_device: 246 unregister_netdevice(peer); 247 return err; 248 } 249 250 static void vxcan_dellink(struct net_device *dev, struct list_head *head) 251 { 252 struct vxcan_priv *priv; 253 struct net_device *peer; 254 255 priv = netdev_priv(dev); 256 peer = rtnl_dereference(priv->peer); 257 258 /* Note : dellink() is called from default_device_exit_batch(), 259 * before a rcu_synchronize() point. The devices are guaranteed 260 * not being freed before one RCU grace period. 261 */ 262 RCU_INIT_POINTER(priv->peer, NULL); 263 unregister_netdevice_queue(dev, head); 264 265 if (peer) { 266 priv = netdev_priv(peer); 267 RCU_INIT_POINTER(priv->peer, NULL); 268 unregister_netdevice_queue(peer, head); 269 } 270 } 271 272 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 273 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 274 }; 275 276 static struct net *vxcan_get_link_net(const struct net_device *dev) 277 { 278 struct vxcan_priv *priv = netdev_priv(dev); 279 struct net_device *peer = rtnl_dereference(priv->peer); 280 281 return peer ? dev_net(peer) : dev_net(dev); 282 } 283 284 static struct rtnl_link_ops vxcan_link_ops = { 285 .kind = DRV_NAME, 286 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv), 287 .setup = vxcan_setup, 288 .newlink = vxcan_newlink, 289 .dellink = vxcan_dellink, 290 .policy = vxcan_policy, 291 .maxtype = VXCAN_INFO_MAX, 292 .get_link_net = vxcan_get_link_net, 293 }; 294 295 static __init int vxcan_init(void) 296 { 297 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 298 299 return rtnl_link_register(&vxcan_link_ops); 300 } 301 302 static __exit void vxcan_exit(void) 303 { 304 rtnl_link_unregister(&vxcan_link_ops); 305 } 306 307 module_init(vxcan_init); 308 module_exit(vxcan_exit); 309