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/ethtool.h> 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/netdevice.h> 16 #include <linux/if_arp.h> 17 #include <linux/if_ether.h> 18 #include <linux/can.h> 19 #include <linux/can/dev.h> 20 #include <linux/can/skb.h> 21 #include <linux/can/vxcan.h> 22 #include <linux/can/can-ml.h> 23 #include <linux/slab.h> 24 #include <net/can.h> 25 #include <net/rtnetlink.h> 26 27 #define DRV_NAME "vxcan" 28 29 MODULE_DESCRIPTION("Virtual CAN Tunnel"); 30 MODULE_LICENSE("GPL"); 31 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); 32 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 33 34 struct vxcan_priv { 35 struct net_device __rcu *peer; 36 netdevice_tracker peer_tracker; 37 }; 38 39 static netdev_tx_t vxcan_xmit(struct sk_buff *oskb, struct net_device *dev) 40 { 41 struct vxcan_priv *priv = netdev_priv(dev); 42 struct net_device *peer; 43 struct net_device_stats *peerstats, *srcstats = &dev->stats; 44 struct can_skb_ext *csx; 45 struct sk_buff *skb; 46 unsigned int len; 47 48 if (can_dropped_invalid_skb(dev, oskb)) 49 return NETDEV_TX_OK; 50 51 rcu_read_lock(); 52 peer = rcu_dereference(priv->peer); 53 if (unlikely(!peer)) { 54 kfree_skb(oskb); 55 dev->stats.tx_dropped++; 56 goto out_unlock; 57 } 58 59 skb_tx_timestamp(oskb); 60 61 skb = skb_clone(oskb, GFP_ATOMIC); 62 if (skb) { 63 consume_skb(oskb); 64 } else { 65 kfree_skb(oskb); 66 goto out_unlock; 67 } 68 69 /* the cloned skb points to the skb extension of the already cloned 70 * oskb with an increased refcount. skb_ext_add() creates a copy to 71 * separate the skb extension data which is needed to start with a 72 * fresh can_gw_hops counter in the other namespace. 73 */ 74 csx = skb_ext_add(skb, SKB_EXT_CAN); 75 if (!csx) { 76 kfree_skb(skb); 77 goto out_unlock; 78 } 79 80 /* reset CAN GW hop counter */ 81 csx->can_gw_hops = 0; 82 /* start with new CAN skb UID in the other namespace */ 83 csx->can_skb_uid = 0; 84 85 skb->pkt_type = PACKET_BROADCAST; 86 skb->dev = peer; 87 skb->ip_summed = CHECKSUM_UNNECESSARY; 88 89 len = can_skb_get_data_len(skb); 90 if (netif_rx(skb) == NET_RX_SUCCESS) { 91 srcstats->tx_packets++; 92 srcstats->tx_bytes += len; 93 peerstats = &peer->stats; 94 peerstats->rx_packets++; 95 peerstats->rx_bytes += len; 96 } 97 98 out_unlock: 99 rcu_read_unlock(); 100 return NETDEV_TX_OK; 101 } 102 103 104 static int vxcan_open(struct net_device *dev) 105 { 106 struct vxcan_priv *priv = netdev_priv(dev); 107 struct net_device *peer = rtnl_dereference(priv->peer); 108 109 if (!peer) 110 return -ENOTCONN; 111 112 if (peer->flags & IFF_UP) { 113 netif_carrier_on(dev); 114 netif_carrier_on(peer); 115 } 116 return 0; 117 } 118 119 static int vxcan_close(struct net_device *dev) 120 { 121 struct vxcan_priv *priv = netdev_priv(dev); 122 struct net_device *peer = rtnl_dereference(priv->peer); 123 124 netif_carrier_off(dev); 125 if (peer) 126 netif_carrier_off(peer); 127 128 return 0; 129 } 130 131 static int vxcan_get_iflink(const struct net_device *dev) 132 { 133 struct vxcan_priv *priv = netdev_priv(dev); 134 struct net_device *peer; 135 int iflink; 136 137 rcu_read_lock(); 138 peer = rcu_dereference(priv->peer); 139 iflink = peer ? READ_ONCE(peer->ifindex) : 0; 140 rcu_read_unlock(); 141 142 return iflink; 143 } 144 145 static void vxcan_set_cap_info(struct net_device *dev) 146 { 147 u32 can_cap = CAN_CAP_CC; 148 149 if (dev->mtu > CAN_MTU) 150 can_cap |= CAN_CAP_FD; 151 152 if (dev->mtu >= CANXL_MIN_MTU) 153 can_cap |= CAN_CAP_XL; 154 155 can_set_cap(dev, can_cap); 156 } 157 158 static int vxcan_change_mtu(struct net_device *dev, int new_mtu) 159 { 160 /* Do not allow changing the MTU while running */ 161 if (dev->flags & IFF_UP) 162 return -EBUSY; 163 164 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU && 165 !can_is_canxl_dev_mtu(new_mtu)) 166 return -EINVAL; 167 168 WRITE_ONCE(dev->mtu, new_mtu); 169 vxcan_set_cap_info(dev); 170 return 0; 171 } 172 173 static const struct net_device_ops vxcan_netdev_ops = { 174 .ndo_open = vxcan_open, 175 .ndo_stop = vxcan_close, 176 .ndo_start_xmit = vxcan_xmit, 177 .ndo_get_iflink = vxcan_get_iflink, 178 .ndo_change_mtu = vxcan_change_mtu, 179 }; 180 181 static const struct ethtool_ops vxcan_ethtool_ops = { 182 .get_ts_info = ethtool_op_get_ts_info, 183 }; 184 185 static void vxcan_setup(struct net_device *dev) 186 { 187 struct can_ml_priv *can_ml; 188 189 dev->type = ARPHRD_CAN; 190 dev->mtu = CANXL_MTU; 191 dev->hard_header_len = 0; 192 dev->addr_len = 0; 193 dev->tx_queue_len = 0; 194 dev->flags = IFF_NOARP; 195 dev->netdev_ops = &vxcan_netdev_ops; 196 dev->ethtool_ops = &vxcan_ethtool_ops; 197 dev->needs_free_netdev = true; 198 199 can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN); 200 can_set_ml_priv(dev, can_ml); 201 vxcan_set_cap_info(dev); 202 } 203 204 /* forward declaration for rtnl_create_link() */ 205 static struct rtnl_link_ops vxcan_link_ops; 206 207 static int vxcan_newlink(struct net_device *dev, 208 struct rtnl_newlink_params *params, 209 struct netlink_ext_ack *extack) 210 { 211 struct net *peer_net = rtnl_newlink_peer_net(params); 212 struct nlattr **data = params->data; 213 struct nlattr **tb = params->tb; 214 struct vxcan_priv *priv; 215 struct net_device *peer; 216 217 struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb; 218 char ifname[IFNAMSIZ]; 219 unsigned char name_assign_type; 220 struct ifinfomsg *ifmp = NULL; 221 int err; 222 223 /* register peer device */ 224 if (data && data[VXCAN_INFO_PEER]) { 225 struct nlattr *nla_peer = data[VXCAN_INFO_PEER]; 226 227 ifmp = nla_data(nla_peer); 228 rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack); 229 tbp = peer_tb; 230 } 231 232 if (ifmp && tbp[IFLA_IFNAME]) { 233 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ); 234 name_assign_type = NET_NAME_USER; 235 } else { 236 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d"); 237 name_assign_type = NET_NAME_ENUM; 238 } 239 240 peer = rtnl_create_link(peer_net, ifname, name_assign_type, 241 &vxcan_link_ops, tbp, extack); 242 if (IS_ERR(peer)) 243 return PTR_ERR(peer); 244 245 if (ifmp && dev->ifindex) 246 peer->ifindex = ifmp->ifi_index; 247 248 err = register_netdevice(peer); 249 if (err < 0) { 250 free_netdev(peer); 251 return err; 252 } 253 254 netif_carrier_off(peer); 255 256 err = rtnl_configure_link(peer, ifmp, 0, NULL); 257 if (err < 0) 258 goto unregister_network_device; 259 260 /* register first device */ 261 if (tb[IFLA_IFNAME]) 262 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ); 263 else 264 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d"); 265 266 err = register_netdevice(dev); 267 if (err < 0) 268 goto unregister_network_device; 269 270 netif_carrier_off(dev); 271 272 /* cross link the device pair */ 273 priv = netdev_priv(dev); 274 rcu_assign_pointer(priv->peer, peer); 275 netdev_hold(peer, &priv->peer_tracker, GFP_KERNEL); 276 277 priv = netdev_priv(peer); 278 rcu_assign_pointer(priv->peer, dev); 279 netdev_hold(dev, &priv->peer_tracker, GFP_KERNEL); 280 281 return 0; 282 283 unregister_network_device: 284 unregister_netdevice(peer); 285 return err; 286 } 287 288 static void vxcan_dellink(struct net_device *dev, struct list_head *head) 289 { 290 netdevice_tracker *peer_tracker; 291 struct vxcan_priv *priv; 292 struct net_device *peer; 293 294 priv = netdev_priv(dev); 295 peer_tracker = &priv->peer_tracker; 296 peer = unrcu_pointer(xchg(&priv->peer, NULL)); 297 if (!peer) 298 return; 299 300 unregister_netdevice_queue(dev, head); 301 302 priv = netdev_priv(peer); 303 dev = unrcu_pointer(xchg(&priv->peer, NULL)); 304 if (dev) 305 unregister_netdevice_queue_net(dev_net(dev), peer, head); 306 307 netdev_put(peer, peer_tracker); 308 netdev_put(dev, &priv->peer_tracker); 309 } 310 311 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = { 312 [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) }, 313 }; 314 315 static struct net *vxcan_get_link_net(const struct net_device *dev) 316 { 317 struct vxcan_priv *priv = netdev_priv(dev); 318 struct net_device *peer = rtnl_dereference(priv->peer); 319 320 return peer ? dev_net(peer) : dev_net(dev); 321 } 322 323 static struct rtnl_link_ops vxcan_link_ops = { 324 .kind = DRV_NAME, 325 .priv_size = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv), 326 .setup = vxcan_setup, 327 .newlink = vxcan_newlink, 328 .dellink = vxcan_dellink, 329 .policy = vxcan_policy, 330 .peer_type = VXCAN_INFO_PEER, 331 .maxtype = VXCAN_INFO_MAX, 332 .get_link_net = vxcan_get_link_net, 333 }; 334 335 static __init int vxcan_init(void) 336 { 337 pr_info("vxcan: Virtual CAN Tunnel driver\n"); 338 339 return rtnl_link_register(&vxcan_link_ops); 340 } 341 342 static __exit void vxcan_exit(void) 343 { 344 rtnl_link_unregister(&vxcan_link_ops); 345 } 346 347 module_init(vxcan_init); 348 module_exit(vxcan_exit); 349