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/slab.h> 22 #include <net/rtnetlink.h> 23 24 #define DRV_NAME "vxcan" 25 26 MODULE_DESCRIPTION("Virtual CAN Tunnel"); 27 MODULE_LICENSE("GPL"); 28 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 29 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 30 31 struct vxcan_priv { 32 struct net_device __rcu *peer; 33 }; 34 35 static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev) 36 { 37 struct vxcan_priv *priv = netdev_priv(dev); 38 struct net_device *peer; 39 struct canfd_frame *cfd = (struct canfd_frame *)skb->data; 40 struct net_device_stats *peerstats, *srcstats = &dev->stats; 41 42 if (can_dropped_invalid_skb(dev, skb)) 43 return NETDEV_TX_OK; 44 45 rcu_read_lock(); 46 peer = rcu_dereference(priv->peer); 47 if (unlikely(!peer)) { 48 kfree_skb(skb); 49 dev->stats.tx_dropped++; 50 goto out_unlock; 51 } 52 53 skb = can_create_echo_skb(skb); 54 if (!skb) 55 goto out_unlock; 56 57 /* reset CAN GW hop counter */ 58 skb->csum_start = 0; 59 skb->pkt_type = PACKET_BROADCAST; 60 skb->dev = peer; 61 skb->ip_summed = CHECKSUM_UNNECESSARY; 62 63 if (netif_rx_ni(skb) == NET_RX_SUCCESS) { 64 srcstats->tx_packets++; 65 srcstats->tx_bytes += cfd->len; 66 peerstats = &peer->stats; 67 peerstats->rx_packets++; 68 peerstats->rx_bytes += cfd->len; 69 } 70 71 out_unlock: 72 rcu_read_unlock(); 73 return NETDEV_TX_OK; 74 } 75 76 77 static int vxcan_open(struct net_device *dev) 78 { 79 struct vxcan_priv *priv = netdev_priv(dev); 80 struct net_device *peer = rtnl_dereference(priv->peer); 81 82 if (!peer) 83 return -ENOTCONN; 84 85 if (peer->flags & IFF_UP) { 86 netif_carrier_on(dev); 87 netif_carrier_on(peer); 88 } 89 return 0; 90 } 91 92 static int vxcan_close(struct net_device *dev) 93 { 94 struct vxcan_priv *priv = netdev_priv(dev); 95 struct net_device *peer = rtnl_dereference(priv->peer); 96 97 netif_carrier_off(dev); 98 if (peer) 99 netif_carrier_off(peer); 100 101 return 0; 102 } 103 104 static int vxcan_get_iflink(const struct net_device *dev) 105 { 106 struct vxcan_priv *priv = netdev_priv(dev); 107 struct net_device *peer; 108 int iflink; 109 110 rcu_read_lock(); 111 peer = rcu_dereference(priv->peer); 112 iflink = peer ? peer->ifindex : 0; 113 rcu_read_unlock(); 114 115 return iflink; 116 } 117 118 static int vxcan_change_mtu(struct net_device *dev, int new_mtu) 119 { 120 /* Do not allow changing the MTU while running */ 121 if (dev->flags & IFF_UP) 122 return -EBUSY; 123 124 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 125 return -EINVAL; 126 127 dev->mtu = new_mtu; 128 return 0; 129 } 130 131 static const struct net_device_ops vxcan_netdev_ops = { 132 .ndo_open = vxcan_open, 133 .ndo_stop = vxcan_close, 134 .ndo_start_xmit = vxcan_xmit, 135 .ndo_get_iflink = vxcan_get_iflink, 136 .ndo_change_mtu = vxcan_change_mtu, 137 }; 138 139 static void vxcan_setup(struct net_device *dev) 140 { 141 dev->type = ARPHRD_CAN; 142 dev->mtu = CANFD_MTU; 143 dev->hard_header_len = 0; 144 dev->addr_len = 0; 145 dev->tx_queue_len = 0; 146 dev->flags = (IFF_NOARP|IFF_ECHO); 147 dev->netdev_ops = &vxcan_netdev_ops; 148 dev->needs_free_netdev = true; 149 } 150 151 /* forward declaration for rtnl_create_link() */ 152 static struct rtnl_link_ops vxcan_link_ops; 153 154 static int vxcan_newlink(struct net *net, struct net_device *dev, 155 struct nlattr *tb[], struct nlattr *data[], 156 struct netlink_ext_ack *extack) 157 { 158 struct vxcan_priv *priv; 159 struct net_device *peer; 160 struct net *peer_net; 161 162 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb; 163 char ifname[IFNAMSIZ]; 164 unsigned char name_assign_type; 165 struct ifinfomsg *ifmp = NULL; 166 int err; 167 168 /* register peer device */ 169 if (data && data[VXCAN_INFO_PEER]) { 170 struct nlattr *nla_peer; 171 172 nla_peer = data[VXCAN_INFO_PEER]; 173 ifmp = nla_data(nla_peer); 174 err = rtnl_nla_parse_ifla(peer_tb, 175 nla_data(nla_peer) + 176 sizeof(struct ifinfomsg), 177 nla_len(nla_peer) - 178 sizeof(struct ifinfomsg), 179 NULL); 180 if (err < 0) 181 return err; 182 183 tbp = peer_tb; 184 } 185 186 if (ifmp && tbp[IFLA_IFNAME]) { 187 nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 188 name_assign_type = NET_NAME_USER; 189 } else { 190 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 191 name_assign_type = NET_NAME_ENUM; 192 } 193 194 peer_net = rtnl_link_get_net(net, tbp); 195 if (IS_ERR(peer_net)) 196 return PTR_ERR(peer_net); 197 198 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 199 &vxcan_link_ops, tbp, extack); 200 if (IS_ERR(peer)) { 201 put_net(peer_net); 202 return PTR_ERR(peer); 203 } 204 205 if (ifmp && dev->ifindex) 206 peer->ifindex = ifmp->ifi_index; 207 208 err = register_netdevice(peer); 209 put_net(peer_net); 210 peer_net = NULL; 211 if (err < 0) { 212 free_netdev(peer); 213 return err; 214 } 215 216 netif_carrier_off(peer); 217 218 err = rtnl_configure_link(peer, ifmp); 219 if (err < 0) 220 goto unregister_network_device; 221 222 /* register first device */ 223 if (tb[IFLA_IFNAME]) 224 nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ); 225 else 226 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d"); 227 228 err = register_netdevice(dev); 229 if (err < 0) 230 goto unregister_network_device; 231 232 netif_carrier_off(dev); 233 234 /* cross link the device pair */ 235 priv = netdev_priv(dev); 236 rcu_assign_pointer(priv->peer, peer); 237 238 priv = netdev_priv(peer); 239 rcu_assign_pointer(priv->peer, dev); 240 241 return 0; 242 243 unregister_network_device: 244 unregister_netdevice(peer); 245 return err; 246 } 247 248 static void vxcan_dellink(struct net_device *dev, struct list_head *head) 249 { 250 struct vxcan_priv *priv; 251 struct net_device *peer; 252 253 priv = netdev_priv(dev); 254 peer = rtnl_dereference(priv->peer); 255 256 /* Note : dellink() is called from default_device_exit_batch(), 257 * before a rcu_synchronize() point. The devices are guaranteed 258 * not being freed before one RCU grace period. 259 */ 260 RCU_INIT_POINTER(priv->peer, NULL); 261 unregister_netdevice_queue(dev, head); 262 263 if (peer) { 264 priv = netdev_priv(peer); 265 RCU_INIT_POINTER(priv->peer, NULL); 266 unregister_netdevice_queue(peer, head); 267 } 268 } 269 270 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 271 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 272 }; 273 274 static struct net *vxcan_get_link_net(const struct net_device *dev) 275 { 276 struct vxcan_priv *priv = netdev_priv(dev); 277 struct net_device *peer = rtnl_dereference(priv->peer); 278 279 return peer ? dev_net(peer) : dev_net(dev); 280 } 281 282 static struct rtnl_link_ops vxcan_link_ops = { 283 .kind = DRV_NAME, 284 .priv_size = sizeof(struct vxcan_priv), 285 .setup = vxcan_setup, 286 .newlink = vxcan_newlink, 287 .dellink = vxcan_dellink, 288 .policy = vxcan_policy, 289 .maxtype = VXCAN_INFO_MAX, 290 .get_link_net = vxcan_get_link_net, 291 }; 292 293 static __init int vxcan_init(void) 294 { 295 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 296 297 return rtnl_link_register(&vxcan_link_ops); 298 } 299 300 static __exit void vxcan_exit(void) 301 { 302 rtnl_link_unregister(&vxcan_link_ops); 303 } 304 305 module_init(vxcan_init); 306 module_exit(vxcan_exit); 307