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 net_device       *dev;
  45         struct sock             *tunnel_sock;
  46         struct l2tp_session     *session;
  47         atomic_long_t           tx_bytes;
  48         atomic_long_t           tx_packets;
  49         atomic_long_t           tx_dropped;
  50         atomic_long_t           rx_bytes;
  51         atomic_long_t           rx_packets;
  52         atomic_long_t           rx_errors;
  53 };
  54
  55 /* via l2tp_session_priv() */
  56 struct l2tp_eth_sess {
  57         struct net_device __rcu *dev;
  58 };
  59
  60
  61 static int l2tp_eth_dev_init(struct net_device *dev)
  62 {
  63         struct l2tp_eth *priv = netdev_priv(dev);
  64
  65         priv->dev = dev;
  66         eth_hw_addr_random(dev);
  67         eth_broadcast_addr(dev->broadcast);
  68         netdev_lockdep_set_classes(dev);
  69
  70         return 0;
  71 }
  72
  73 static void l2tp_eth_dev_uninit(struct net_device *dev)
  74 {
  75         struct l2tp_eth *priv = netdev_priv(dev);
  76         struct l2tp_eth_sess *spriv;
  77
  78         spriv = l2tp_session_priv(priv->session);
  79         RCU_INIT_POINTER(spriv->dev, NULL);
  80         /* No need for synchronize_net() here. We're called by
  81          * unregister_netdev*(), which does the synchronisation for us.
  82          */
  83 }
  84
  85 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
  86 {
  87         struct l2tp_eth *priv = netdev_priv(dev);
  88         struct l2tp_session *session = priv->session;
  89         unsigned int len = skb->len;
  90         int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
  91
  92         if (likely(ret == NET_XMIT_SUCCESS)) {
  93                 atomic_long_add(len, &priv->tx_bytes);
  94                 atomic_long_inc(&priv->tx_packets);
  95         } else {
  96                 atomic_long_inc(&priv->tx_dropped);
  97         }
  98         return NETDEV_TX_OK;
  99 }
 100
 101 static void l2tp_eth_get_stats64(struct net_device *dev,
 102                                  struct rtnl_link_stats64 *stats)
 103 {
 104         struct l2tp_eth *priv = netdev_priv(dev);
 105
 106         stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
 107         stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
 108         stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
 109         stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
 110         stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
 111         stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);
 112
 113 }
 114
 115 static const struct net_device_ops l2tp_eth_netdev_ops = {
 116         .ndo_init               = l2tp_eth_dev_init,
 117         .ndo_uninit             = l2tp_eth_dev_uninit,
 118         .ndo_start_xmit         = l2tp_eth_dev_xmit,
 119         .ndo_get_stats64        = l2tp_eth_get_stats64,
 120         .ndo_set_mac_address    = eth_mac_addr,
 121 };
 122
 123 static struct device_type l2tpeth_type = {
 124         .name = "l2tpeth",
 125 };
 126
 127 static void l2tp_eth_dev_setup(struct net_device *dev)
 128 {
 129         SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 130         ether_setup(dev);
 131         dev->priv_flags         &= ~IFF_TX_SKB_SHARING;
 132         dev->features           |= NETIF_F_LLTX;
 133         dev->netdev_ops         = &l2tp_eth_netdev_ops;
 134         dev->needs_free_netdev  = true;
 135 }
 136
 137 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 138 {
 139         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 140         struct net_device *dev;
 141         struct l2tp_eth *priv;
 142
 143         if (session->debug & L2TP_MSG_DATA) {
 144                 unsigned int length;
 145
 146                 length = min(32u, skb->len);
 147                 if (!pskb_may_pull(skb, length))
 148                         goto error;
 149
 150                 pr_debug("%s: eth recv\n", session->name);
 151                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 152         }
 153
 154         if (!pskb_may_pull(skb, ETH_HLEN))
 155                 goto error;
 156
 157         secpath_reset(skb);
 158
 159         /* checksums verified by L2TP */
 160         skb->ip_summed = CHECKSUM_NONE;
 161
 162         skb_dst_drop(skb);
 163         nf_reset(skb);
 164
 165         rcu_read_lock();
 166         dev = rcu_dereference(spriv->dev);
 167         if (!dev)
 168                 goto error_rcu;
 169
 170         priv = netdev_priv(dev);
 171         if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 172                 atomic_long_inc(&priv->rx_packets);
 173                 atomic_long_add(data_len, &priv->rx_bytes);
 174         } else {
 175                 atomic_long_inc(&priv->rx_errors);
 176         }
 177         rcu_read_unlock();
 178
 179         return;
 180
 181 error_rcu:
 182         rcu_read_unlock();
 183 error:
 184         kfree_skb(skb);
 185 }
 186
 187 static void l2tp_eth_delete(struct l2tp_session *session)
 188 {
 189         struct l2tp_eth_sess *spriv;
 190         struct net_device *dev;
 191
 192         if (session) {
 193                 spriv = l2tp_session_priv(session);
 194
 195                 rtnl_lock();
 196                 dev = rtnl_dereference(spriv->dev);
 197                 if (dev) {
 198                         unregister_netdevice(dev);
 199                         rtnl_unlock();
 200                         module_put(THIS_MODULE);
 201                 } else {
 202                         rtnl_unlock();
 203                 }
 204         }
 205 }
 206
 207 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 208 static void l2tp_eth_show(struct seq_file *m, void *arg)
 209 {
 210         struct l2tp_session *session = arg;
 211         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 212         struct net_device *dev;
 213
 214         rcu_read_lock();
 215         dev = rcu_dereference(spriv->dev);
 216         if (!dev) {
 217                 rcu_read_unlock();
 218                 return;
 219         }
 220         dev_hold(dev);
 221         rcu_read_unlock();
 222
 223         seq_printf(m, "   interface %s\n", dev->name);
 224
 225         dev_put(dev);
 226 }
 227 #endif
 228
 229 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 230                                 struct l2tp_session *session,
 231                                 struct net_device *dev)
 232 {
 233         unsigned int overhead = 0;
 234         struct dst_entry *dst;
 235         u32 l3_overhead = 0;
 236
 237         /* if the encap is UDP, account for UDP header size */
 238         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 239                 overhead += sizeof(struct udphdr);
 240                 dev->needed_headroom += sizeof(struct udphdr);
 241         }
 242         if (session->mtu != 0) {
 243                 dev->mtu = session->mtu;
 244                 dev->needed_headroom += session->hdr_len;
 245                 return;
 246         }
 247         lock_sock(tunnel->sock);
 248         l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
 249         release_sock(tunnel->sock);
 250         if (l3_overhead == 0) {
 251                 /* L3 Overhead couldn't be identified, this could be
 252                  * because tunnel->sock was NULL or the socket's
 253                  * address family was not IPv4 or IPv6,
 254                  * dev mtu stays at 1500.
 255                  */
 256                 return;
 257         }
 258         /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
 259          * UDP overhead, if any, was already factored in above.
 260          */
 261         overhead += session->hdr_len + ETH_HLEN + l3_overhead;
 262
 263         /* If PMTU discovery was enabled, use discovered MTU on L2TP device */
 264         dst = sk_dst_get(tunnel->sock);
 265         if (dst) {
 266                 /* dst_mtu will use PMTU if found, else fallback to intf MTU */
 267                 u32 pmtu = dst_mtu(dst);
 268
 269                 if (pmtu != 0)
 270                         dev->mtu = pmtu;
 271                 dst_release(dst);
 272         }
 273         session->mtu = dev->mtu - overhead;
 274         dev->mtu = session->mtu;
 275         dev->needed_headroom += session->hdr_len;
 276 }
 277
 278 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 279                            u32 session_id, u32 peer_session_id,
 280                            struct l2tp_session_cfg *cfg)
 281 {
 282         unsigned char name_assign_type;
 283         struct net_device *dev;
 284         char name[IFNAMSIZ];
 285         struct l2tp_session *session;
 286         struct l2tp_eth *priv;
 287         struct l2tp_eth_sess *spriv;
 288         int rc;
 289
 290         if (cfg->ifname) {
 291                 strlcpy(name, cfg->ifname, IFNAMSIZ);
 292                 name_assign_type = NET_NAME_USER;
 293         } else {
 294                 strcpy(name, L2TP_ETH_DEV_NAME);
 295                 name_assign_type = NET_NAME_ENUM;
 296         }
 297
 298         session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 299                                       peer_session_id, cfg);
 300         if (IS_ERR(session)) {
 301                 rc = PTR_ERR(session);
 302                 goto err;
 303         }
 304
 305         dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
 306                            l2tp_eth_dev_setup);
 307         if (!dev) {
 308                 rc = -ENOMEM;
 309                 goto err_sess;
 310         }
 311
 312         dev_net_set(dev, net);
 313         dev->min_mtu = 0;
 314         dev->max_mtu = ETH_MAX_MTU;
 315         l2tp_eth_adjust_mtu(tunnel, session, dev);
 316
 317         priv = netdev_priv(dev);
 318         priv->dev = dev;
 319         priv->session = session;
 320
 321         priv->tunnel_sock = tunnel->sock;
 322         session->recv_skb = l2tp_eth_dev_recv;
 323         session->session_close = l2tp_eth_delete;
 324 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 325         session->show = l2tp_eth_show;
 326 #endif
 327
 328         spriv = l2tp_session_priv(session);
 329
 330         l2tp_session_inc_refcount(session);
 331
 332         rtnl_lock();
 333
 334         /* Register both device and session while holding the rtnl lock. This
 335          * ensures that l2tp_eth_delete() will see that there's a device to
 336          * unregister, even if it happened to run before we assign spriv->dev.
 337          */
 338         rc = l2tp_session_register(session, tunnel);
 339         if (rc < 0) {
 340                 rtnl_unlock();
 341                 goto err_sess_dev;
 342         }
 343
 344         rc = register_netdevice(dev);
 345         if (rc < 0) {
 346                 rtnl_unlock();
 347                 l2tp_session_delete(session);
 348                 l2tp_session_dec_refcount(session);
 349                 free_netdev(dev);
 350
 351                 return rc;
 352         }
 353
 354         strlcpy(session->ifname, dev->name, IFNAMSIZ);
 355         rcu_assign_pointer(spriv->dev, dev);
 356
 357         rtnl_unlock();
 358
 359         l2tp_session_dec_refcount(session);
 360
 361         __module_get(THIS_MODULE);
 362
 363         return 0;
 364
 365 err_sess_dev:
 366         l2tp_session_dec_refcount(session);
 367         free_netdev(dev);
 368 err_sess:
 369         kfree(session);
 370 err:
 371         return rc;
 372 }
 373
 374
 375 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 376         .session_create = l2tp_eth_create,
 377         .session_delete = l2tp_session_delete,
 378 };
 379
 380
 381 static int __init l2tp_eth_init(void)
 382 {
 383         int err = 0;
 384
 385         err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 386         if (err)
 387                 goto err;
 388
 389         pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
 390
 391         return 0;
 392
 393 err:
 394         return err;
 395 }
 396
 397 static void __exit l2tp_eth_exit(void)
 398 {
 399         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 400 }
 401
 402 module_init(l2tp_eth_init);
 403 module_exit(l2tp_eth_exit);
 404
 405 MODULE_LICENSE("GPL");
 406 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 407 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 408 MODULE_VERSION("1.0");
 409 MODULE_ALIAS_L2TP_PWTYPE(5);