net/l2tp/l2tp_eth.c

   1 /*
   2  * L2TPv3 ethernet pseudowire driver
   3  *
   4  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/socket.h>
  17 #include <linux/hash.h>
  18 #include <linux/l2tp.h>
  19 #include <linux/in.h>
  20 #include <linux/etherdevice.h>
  21 #include <linux/spinlock.h>
  22 #include <net/sock.h>
  23 #include <net/ip.h>
  24 #include <net/icmp.h>
  25 #include <net/udp.h>
  26 #include <net/inet_common.h>
  27 #include <net/inet_hashtables.h>
  28 #include <net/tcp_states.h>
  29 #include <net/protocol.h>
  30 #include <net/xfrm.h>
  31 #include <net/net_namespace.h>
  32 #include <net/netns/generic.h>
  33 #include <linux/ip.h>
  34 #include <linux/ipv6.h>
  35 #include <linux/udp.h>
  36
  37 #include "l2tp_core.h"
  38
  39 /* Default device name. May be overridden by name specified by user */
  40 #define L2TP_ETH_DEV_NAME       "l2tpeth%d"
  41
  42 /* via netdev_priv() */
  43 struct l2tp_eth {
  44         struct l2tp_session     *session;
  45         atomic_long_t           tx_bytes;
  46         atomic_long_t           tx_packets;
  47         atomic_long_t           tx_dropped;
  48         atomic_long_t           rx_bytes;
  49         atomic_long_t           rx_packets;
  50         atomic_long_t           rx_errors;
  51 };
  52
  53 /* via l2tp_session_priv() */
  54 struct l2tp_eth_sess {
  55         struct net_device __rcu *dev;
  56 };
  57
  58
  59 static int l2tp_eth_dev_init(struct net_device *dev)
  60 {
  61         eth_hw_addr_random(dev);
  62         eth_broadcast_addr(dev->broadcast);
  63         netdev_lockdep_set_classes(dev);
  64
  65         return 0;
  66 }
  67
  68 static void l2tp_eth_dev_uninit(struct net_device *dev)
  69 {
  70         struct l2tp_eth *priv = netdev_priv(dev);
  71         struct l2tp_eth_sess *spriv;
  72
  73         spriv = l2tp_session_priv(priv->session);
  74         RCU_INIT_POINTER(spriv->dev, NULL);
  75         /* No need for synchronize_net() here. We're called by
  76          * unregister_netdev*(), which does the synchronisation for us.
  77          */
  78 }
  79
  80 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
  81 {
  82         struct l2tp_eth *priv = netdev_priv(dev);
  83         struct l2tp_session *session = priv->session;
  84         unsigned int len = skb->len;
  85         int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
  86
  87         if (likely(ret == NET_XMIT_SUCCESS)) {
  88                 atomic_long_add(len, &priv->tx_bytes);
  89                 atomic_long_inc(&priv->tx_packets);
  90         } else {
  91                 atomic_long_inc(&priv->tx_dropped);
  92         }
  93         return NETDEV_TX_OK;
  94 }
  95
  96 static void l2tp_eth_get_stats64(struct net_device *dev,
  97                                  struct rtnl_link_stats64 *stats)
  98 {
  99         struct l2tp_eth *priv = netdev_priv(dev);
 100
 101         stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
 102         stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
 103         stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
 104         stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
 105         stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
 106         stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);
 107
 108 }
 109
 110 static const struct net_device_ops l2tp_eth_netdev_ops = {
 111         .ndo_init               = l2tp_eth_dev_init,
 112         .ndo_uninit             = l2tp_eth_dev_uninit,
 113         .ndo_start_xmit         = l2tp_eth_dev_xmit,
 114         .ndo_get_stats64        = l2tp_eth_get_stats64,
 115         .ndo_set_mac_address    = eth_mac_addr,
 116 };
 117
 118 static struct device_type l2tpeth_type = {
 119         .name = "l2tpeth",
 120 };
 121
 122 static void l2tp_eth_dev_setup(struct net_device *dev)
 123 {
 124         SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 125         ether_setup(dev);
 126         dev->priv_flags         &= ~IFF_TX_SKB_SHARING;
 127         dev->features           |= NETIF_F_LLTX;
 128         dev->netdev_ops         = &l2tp_eth_netdev_ops;
 129         dev->needs_free_netdev  = true;
 130 }
 131
 132 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 133 {
 134         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 135         struct net_device *dev;
 136         struct l2tp_eth *priv;
 137
 138         if (session->debug & L2TP_MSG_DATA) {
 139                 unsigned int length;
 140
 141                 length = min(32u, skb->len);
 142                 if (!pskb_may_pull(skb, length))
 143                         goto error;
 144
 145                 pr_debug("%s: eth recv\n", session->name);
 146                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 147         }
 148
 149         if (!pskb_may_pull(skb, ETH_HLEN))
 150                 goto error;
 151
 152         secpath_reset(skb);
 153
 154         /* checksums verified by L2TP */
 155         skb->ip_summed = CHECKSUM_NONE;
 156
 157         skb_dst_drop(skb);
 158         nf_reset(skb);
 159
 160         rcu_read_lock();
 161         dev = rcu_dereference(spriv->dev);
 162         if (!dev)
 163                 goto error_rcu;
 164
 165         priv = netdev_priv(dev);
 166         if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 167                 atomic_long_inc(&priv->rx_packets);
 168                 atomic_long_add(data_len, &priv->rx_bytes);
 169         } else {
 170                 atomic_long_inc(&priv->rx_errors);
 171         }
 172         rcu_read_unlock();
 173
 174         return;
 175
 176 error_rcu:
 177         rcu_read_unlock();
 178 error:
 179         kfree_skb(skb);
 180 }
 181
 182 static void l2tp_eth_delete(struct l2tp_session *session)
 183 {
 184         struct l2tp_eth_sess *spriv;
 185         struct net_device *dev;
 186
 187         if (session) {
 188                 spriv = l2tp_session_priv(session);
 189
 190                 rtnl_lock();
 191                 dev = rtnl_dereference(spriv->dev);
 192                 if (dev) {
 193                         unregister_netdevice(dev);
 194                         rtnl_unlock();
 195                         module_put(THIS_MODULE);
 196                 } else {
 197                         rtnl_unlock();
 198                 }
 199         }
 200 }
 201
 202 static void l2tp_eth_show(struct seq_file *m, void *arg)
 203 {
 204         struct l2tp_session *session = arg;
 205         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 206         struct net_device *dev;
 207
 208         rcu_read_lock();
 209         dev = rcu_dereference(spriv->dev);
 210         if (!dev) {
 211                 rcu_read_unlock();
 212                 return;
 213         }
 214         dev_hold(dev);
 215         rcu_read_unlock();
 216
 217         seq_printf(m, "   interface %s\n", dev->name);
 218
 219         dev_put(dev);
 220 }
 221
 222 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 223                                 struct l2tp_session *session,
 224                                 struct net_device *dev)
 225 {
 226         unsigned int overhead = 0;
 227         u32 l3_overhead = 0;
 228         u32 mtu;
 229
 230         /* if the encap is UDP, account for UDP header size */
 231         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 232                 overhead += sizeof(struct udphdr);
 233                 dev->needed_headroom += sizeof(struct udphdr);
 234         }
 235
 236         lock_sock(tunnel->sock);
 237         l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
 238         release_sock(tunnel->sock);
 239
 240         if (l3_overhead == 0) {
 241                 /* L3 Overhead couldn't be identified, this could be
 242                  * because tunnel->sock was NULL or the socket's
 243                  * address family was not IPv4 or IPv6,
 244                  * dev mtu stays at 1500.
 245                  */
 246                 return;
 247         }
 248         /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
 249          * UDP overhead, if any, was already factored in above.
 250          */
 251         overhead += session->hdr_len + ETH_HLEN + l3_overhead;
 252
 253         mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;
 254         if (mtu < dev->min_mtu || mtu > dev->max_mtu)
 255                 dev->mtu = ETH_DATA_LEN - overhead;
 256         else
 257                 dev->mtu = mtu;
 258
 259         dev->needed_headroom += session->hdr_len;
 260 }
 261
 262 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 263                            u32 session_id, u32 peer_session_id,
 264                            struct l2tp_session_cfg *cfg)
 265 {
 266         unsigned char name_assign_type;
 267         struct net_device *dev;
 268         char name[IFNAMSIZ];
 269         struct l2tp_session *session;
 270         struct l2tp_eth *priv;
 271         struct l2tp_eth_sess *spriv;
 272         int rc;
 273
 274         if (cfg->ifname) {
 275                 strlcpy(name, cfg->ifname, IFNAMSIZ);
 276                 name_assign_type = NET_NAME_USER;
 277         } else {
 278                 strcpy(name, L2TP_ETH_DEV_NAME);
 279                 name_assign_type = NET_NAME_ENUM;
 280         }
 281
 282         session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 283                                       peer_session_id, cfg);
 284         if (IS_ERR(session)) {
 285                 rc = PTR_ERR(session);
 286                 goto err;
 287         }
 288
 289         dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
 290                            l2tp_eth_dev_setup);
 291         if (!dev) {
 292                 rc = -ENOMEM;
 293                 goto err_sess;
 294         }
 295
 296         dev_net_set(dev, net);
 297         dev->min_mtu = 0;
 298         dev->max_mtu = ETH_MAX_MTU;
 299         l2tp_eth_adjust_mtu(tunnel, session, dev);
 300
 301         priv = netdev_priv(dev);
 302         priv->session = session;
 303
 304         session->recv_skb = l2tp_eth_dev_recv;
 305         session->session_close = l2tp_eth_delete;
 306         if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
 307                 session->show = l2tp_eth_show;
 308
 309         spriv = l2tp_session_priv(session);
 310
 311         l2tp_session_inc_refcount(session);
 312
 313         rtnl_lock();
 314
 315         /* Register both device and session while holding the rtnl lock. This
 316          * ensures that l2tp_eth_delete() will see that there's a device to
 317          * unregister, even if it happened to run before we assign spriv->dev.
 318          */
 319         rc = l2tp_session_register(session, tunnel);
 320         if (rc < 0) {
 321                 rtnl_unlock();
 322                 goto err_sess_dev;
 323         }
 324
 325         rc = register_netdevice(dev);
 326         if (rc < 0) {
 327                 rtnl_unlock();
 328                 l2tp_session_delete(session);
 329                 l2tp_session_dec_refcount(session);
 330                 free_netdev(dev);
 331
 332                 return rc;
 333         }
 334
 335         strlcpy(session->ifname, dev->name, IFNAMSIZ);
 336         rcu_assign_pointer(spriv->dev, dev);
 337
 338         rtnl_unlock();
 339
 340         l2tp_session_dec_refcount(session);
 341
 342         __module_get(THIS_MODULE);
 343
 344         return 0;
 345
 346 err_sess_dev:
 347         l2tp_session_dec_refcount(session);
 348         free_netdev(dev);
 349 err_sess:
 350         kfree(session);
 351 err:
 352         return rc;
 353 }
 354
 355
 356 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 357         .session_create = l2tp_eth_create,
 358         .session_delete = l2tp_session_delete,
 359 };
 360
 361
 362 static int __init l2tp_eth_init(void)
 363 {
 364         int err = 0;
 365
 366         err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 367         if (err)
 368                 goto err;
 369
 370         pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
 371
 372         return 0;
 373
 374 err:
 375         return err;
 376 }
 377
 378 static void __exit l2tp_eth_exit(void)
 379 {
 380         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 381 }
 382
 383 module_init(l2tp_eth_init);
 384 module_exit(l2tp_eth_exit);
 385
 386 MODULE_LICENSE("GPL");
 387 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 388 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 389 MODULE_VERSION("1.0");
 390 MODULE_ALIAS_L2TP_PWTYPE(5);