drivers/net/can/vxcan.c

   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/rtnetlink.h>
  25
  26 #define DRV_NAME "vxcan"
  27
  28 MODULE_DESCRIPTION("Virtual CAN Tunnel");
  29 MODULE_LICENSE("GPL");
  30 MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
  31 MODULE_ALIAS_RTNL_LINK(DRV_NAME);
  32
  33 struct vxcan_priv {
  34         struct net_device __rcu *peer;
  35 };
  36
  37 static netdev_tx_t vxcan_xmit(struct sk_buff *oskb, struct net_device *dev)
  38 {
  39         struct vxcan_priv *priv = netdev_priv(dev);
  40         struct net_device *peer;
  41         struct net_device_stats *peerstats, *srcstats = &dev->stats;
  42         struct sk_buff *skb;
  43         unsigned int 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_tx_timestamp(oskb);
  57
  58         skb = skb_clone(oskb, GFP_ATOMIC);
  59         if (skb) {
  60                 consume_skb(oskb);
  61         } else {
  62                 kfree_skb(oskb);
  63                 goto out_unlock;
  64         }
  65
  66         /* reset CAN GW hop counter */
  67         skb->csum_start = 0;
  68         skb->pkt_type   = PACKET_BROADCAST;
  69         skb->dev        = peer;
  70         skb->ip_summed  = CHECKSUM_UNNECESSARY;
  71
  72         len = can_skb_get_data_len(skb);
  73         if (netif_rx(skb) == NET_RX_SUCCESS) {
  74                 srcstats->tx_packets++;
  75                 srcstats->tx_bytes += len;
  76                 peerstats = &peer->stats;
  77                 peerstats->rx_packets++;
  78                 peerstats->rx_bytes += len;
  79         }
  80
  81 out_unlock:
  82         rcu_read_unlock();
  83         return NETDEV_TX_OK;
  84 }
  85
  86
  87 static int vxcan_open(struct net_device *dev)
  88 {
  89         struct vxcan_priv *priv = netdev_priv(dev);
  90         struct net_device *peer = rtnl_dereference(priv->peer);
  91
  92         if (!peer)
  93                 return -ENOTCONN;
  94
  95         if (peer->flags & IFF_UP) {
  96                 netif_carrier_on(dev);
  97                 netif_carrier_on(peer);
  98         }
  99         return 0;
 100 }
 101
 102 static int vxcan_close(struct net_device *dev)
 103 {
 104         struct vxcan_priv *priv = netdev_priv(dev);
 105         struct net_device *peer = rtnl_dereference(priv->peer);
 106
 107         netif_carrier_off(dev);
 108         if (peer)
 109                 netif_carrier_off(peer);
 110
 111         return 0;
 112 }
 113
 114 static int vxcan_get_iflink(const struct net_device *dev)
 115 {
 116         struct vxcan_priv *priv = netdev_priv(dev);
 117         struct net_device *peer;
 118         int iflink;
 119
 120         rcu_read_lock();
 121         peer = rcu_dereference(priv->peer);
 122         iflink = peer ? READ_ONCE(peer->ifindex) : 0;
 123         rcu_read_unlock();
 124
 125         return iflink;
 126 }
 127
 128 static int vxcan_change_mtu(struct net_device *dev, int new_mtu)
 129 {
 130         /* Do not allow changing the MTU while running */
 131         if (dev->flags & IFF_UP)
 132                 return -EBUSY;
 133
 134         if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU &&
 135             !can_is_canxl_dev_mtu(new_mtu))
 136                 return -EINVAL;
 137
 138         WRITE_ONCE(dev->mtu, new_mtu);
 139         return 0;
 140 }
 141
 142 static const struct net_device_ops vxcan_netdev_ops = {
 143         .ndo_open       = vxcan_open,
 144         .ndo_stop       = vxcan_close,
 145         .ndo_start_xmit = vxcan_xmit,
 146         .ndo_get_iflink = vxcan_get_iflink,
 147         .ndo_change_mtu = vxcan_change_mtu,
 148 };
 149
 150 static const struct ethtool_ops vxcan_ethtool_ops = {
 151         .get_ts_info = ethtool_op_get_ts_info,
 152 };
 153
 154 static void vxcan_setup(struct net_device *dev)
 155 {
 156         struct can_ml_priv *can_ml;
 157
 158         dev->type               = ARPHRD_CAN;
 159         dev->mtu                = CANFD_MTU;
 160         dev->hard_header_len    = 0;
 161         dev->addr_len           = 0;
 162         dev->tx_queue_len       = 0;
 163         dev->flags              = IFF_NOARP;
 164         dev->netdev_ops         = &vxcan_netdev_ops;
 165         dev->ethtool_ops        = &vxcan_ethtool_ops;
 166         dev->needs_free_netdev  = true;
 167
 168         can_ml = netdev_priv(dev) + ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN);
 169         can_set_ml_priv(dev, can_ml);
 170 }
 171
 172 /* forward declaration for rtnl_create_link() */
 173 static struct rtnl_link_ops vxcan_link_ops;
 174
 175 static int vxcan_newlink(struct net *net, struct net_device *dev,
 176                          struct nlattr *tb[], struct nlattr *data[],
 177                          struct netlink_ext_ack *extack)
 178 {
 179         struct vxcan_priv *priv;
 180         struct net_device *peer;
 181         struct net *peer_net;
 182
 183         struct nlattr *peer_tb[IFLA_MAX + 1], **tbp = tb;
 184         char ifname[IFNAMSIZ];
 185         unsigned char name_assign_type;
 186         struct ifinfomsg *ifmp = NULL;
 187         int err;
 188
 189         /* register peer device */
 190         if (data && data[VXCAN_INFO_PEER]) {
 191                 struct nlattr *nla_peer = data[VXCAN_INFO_PEER];
 192
 193                 ifmp = nla_data(nla_peer);
 194                 rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack);
 195                 tbp = peer_tb;
 196         }
 197
 198         if (ifmp && tbp[IFLA_IFNAME]) {
 199                 nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
 200                 name_assign_type = NET_NAME_USER;
 201         } else {
 202                 snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
 203                 name_assign_type = NET_NAME_ENUM;
 204         }
 205
 206         peer_net = rtnl_link_get_net(net, tbp);
 207         peer = rtnl_create_link(peer_net, ifname, name_assign_type,
 208                                 &vxcan_link_ops, tbp, extack);
 209         if (IS_ERR(peer)) {
 210                 put_net(peer_net);
 211                 return PTR_ERR(peer);
 212         }
 213
 214         if (ifmp && dev->ifindex)
 215                 peer->ifindex = ifmp->ifi_index;
 216
 217         err = register_netdevice(peer);
 218         put_net(peer_net);
 219         peer_net = NULL;
 220         if (err < 0) {
 221                 free_netdev(peer);
 222                 return err;
 223         }
 224
 225         netif_carrier_off(peer);
 226
 227         err = rtnl_configure_link(peer, ifmp, 0, NULL);
 228         if (err < 0)
 229                 goto unregister_network_device;
 230
 231         /* register first device */
 232         if (tb[IFLA_IFNAME])
 233                 nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
 234         else
 235                 snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
 236
 237         err = register_netdevice(dev);
 238         if (err < 0)
 239                 goto unregister_network_device;
 240
 241         netif_carrier_off(dev);
 242
 243         /* cross link the device pair */
 244         priv = netdev_priv(dev);
 245         rcu_assign_pointer(priv->peer, peer);
 246
 247         priv = netdev_priv(peer);
 248         rcu_assign_pointer(priv->peer, dev);
 249
 250         return 0;
 251
 252 unregister_network_device:
 253         unregister_netdevice(peer);
 254         return err;
 255 }
 256
 257 static void vxcan_dellink(struct net_device *dev, struct list_head *head)
 258 {
 259         struct vxcan_priv *priv;
 260         struct net_device *peer;
 261
 262         priv = netdev_priv(dev);
 263         peer = rtnl_dereference(priv->peer);
 264
 265         /* Note : dellink() is called from default_device_exit_batch(),
 266          * before a rcu_synchronize() point. The devices are guaranteed
 267          * not being freed before one RCU grace period.
 268          */
 269         RCU_INIT_POINTER(priv->peer, NULL);
 270         unregister_netdevice_queue(dev, head);
 271
 272         if (peer) {
 273                 priv = netdev_priv(peer);
 274                 RCU_INIT_POINTER(priv->peer, NULL);
 275                 unregister_netdevice_queue(peer, head);
 276         }
 277 }
 278
 279 static const struct nla_policy vxcan_policy[VXCAN_INFO_MAX + 1] = {
 280         [VXCAN_INFO_PEER] = { .len = sizeof(struct ifinfomsg) },
 281 };
 282
 283 static struct net *vxcan_get_link_net(const struct net_device *dev)
 284 {
 285         struct vxcan_priv *priv = netdev_priv(dev);
 286         struct net_device *peer = rtnl_dereference(priv->peer);
 287
 288         return peer ? dev_net(peer) : dev_net(dev);
 289 }
 290
 291 static struct rtnl_link_ops vxcan_link_ops = {
 292         .kind           = DRV_NAME,
 293         .priv_size      = ALIGN(sizeof(struct vxcan_priv), NETDEV_ALIGN) + sizeof(struct can_ml_priv),
 294         .setup          = vxcan_setup,
 295         .newlink        = vxcan_newlink,
 296         .dellink        = vxcan_dellink,
 297         .policy         = vxcan_policy,
 298         .peer_type      = VXCAN_INFO_PEER,
 299         .maxtype        = VXCAN_INFO_MAX,
 300         .get_link_net   = vxcan_get_link_net,
 301 };
 302
 303 static __init int vxcan_init(void)
 304 {
 305         pr_info("vxcan: Virtual CAN Tunnel driver\n");
 306
 307         return rtnl_link_register(&vxcan_link_ops);
 308 }
 309
 310 static __exit void vxcan_exit(void)
 311 {
 312         rtnl_link_unregister(&vxcan_link_ops);
 313 }
 314
 315 module_init(vxcan_init);
 316 module_exit(vxcan_exit);