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 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/socket.h>
  15 #include <linux/hash.h>
  16 #include <linux/l2tp.h>
  17 #include <linux/in.h>
  18 #include <linux/etherdevice.h>
  19 #include <linux/spinlock.h>
  20 #include <net/sock.h>
  21 #include <net/ip.h>
  22 #include <net/icmp.h>
  23 #include <net/udp.h>
  24 #include <net/inet_common.h>
  25 #include <net/inet_hashtables.h>
  26 #include <net/tcp_states.h>
  27 #include <net/protocol.h>
  28 #include <net/xfrm.h>
  29 #include <net/net_namespace.h>
  30 #include <net/netns/generic.h>
  31
  32 #include "l2tp_core.h"
  33
  34 /* Default device name. May be overridden by name specified by user */
  35 #define L2TP_ETH_DEV_NAME       "l2tpeth%d"
  36
  37 /* via netdev_priv() */
  38 struct l2tp_eth {
  39         struct net_device       *dev;
  40         struct sock             *tunnel_sock;
  41         struct l2tp_session     *session;
  42 };
  43
  44 /* via l2tp_session_priv() */
  45 struct l2tp_eth_sess {
  46         struct net_device __rcu *dev;
  47 };
  48
  49
  50 static int l2tp_eth_dev_init(struct net_device *dev)
  51 {
  52         struct l2tp_eth *priv = netdev_priv(dev);
  53
  54         priv->dev = dev;
  55         random_ether_addr(dev->dev_addr);
  56         memset(&dev->broadcast[0], 0xff, 6);
  57
  58         return 0;
  59 }
  60
  61 static void l2tp_eth_dev_uninit(struct net_device *dev)
  62 {
  63         struct l2tp_eth *priv = netdev_priv(dev);
  64         struct l2tp_eth_sess *spriv;
  65
  66         spriv = l2tp_session_priv(priv->session);
  67         RCU_INIT_POINTER(spriv->dev, NULL);
  68         /* No need for synchronize_net() here. We're called by
  69          * unregister_netdev*(), which does the synchronisation for us.
  70          */
  71 }
  72
  73 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
  74 {
  75         struct l2tp_eth *priv = netdev_priv(dev);
  76         struct l2tp_session *session = priv->session;
  77
  78         l2tp_xmit_skb(session, skb, session->hdr_len);
  79
  80         dev->stats.tx_bytes += skb->len;
  81         dev->stats.tx_packets++;
  82
  83         return 0;
  84 }
  85
  86 static struct net_device_ops l2tp_eth_netdev_ops = {
  87         .ndo_init               = l2tp_eth_dev_init,
  88         .ndo_uninit             = l2tp_eth_dev_uninit,
  89         .ndo_start_xmit         = l2tp_eth_dev_xmit,
  90 };
  91
  92 static void l2tp_eth_dev_setup(struct net_device *dev)
  93 {
  94         ether_setup(dev);
  95         dev->priv_flags &= ~IFF_TX_SKB_SHARING;
  96         dev->netdev_ops         = &l2tp_eth_netdev_ops;
  97         dev->destructor         = free_netdev;
  98 }
  99
 100 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 101 {
 102         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 103         struct net_device *dev;
 104
 105         if (session->debug & L2TP_MSG_DATA) {
 106                 unsigned int length;
 107                 int offset;
 108                 u8 *ptr = skb->data;
 109
 110                 length = min(32u, skb->len);
 111                 if (!pskb_may_pull(skb, length))
 112                         goto error;
 113
 114                 printk(KERN_DEBUG "%s: eth recv: ", session->name);
 115
 116                 offset = 0;
 117                 do {
 118                         printk(" %02X", ptr[offset]);
 119                 } while (++offset < length);
 120
 121                 printk("\n");
 122         }
 123
 124         if (!pskb_may_pull(skb, ETH_HLEN))
 125                 goto error;
 126
 127         secpath_reset(skb);
 128
 129         /* checksums verified by L2TP */
 130         skb->ip_summed = CHECKSUM_NONE;
 131
 132         skb_dst_drop(skb);
 133         nf_reset(skb);
 134
 135         rcu_read_lock();
 136         dev = rcu_dereference(spriv->dev);
 137         if (!dev)
 138                 goto error_rcu;
 139
 140         if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 141                 dev->stats.rx_packets++;
 142                 dev->stats.rx_bytes += data_len;
 143         } else
 144                 dev->stats.rx_errors++;
 145         rcu_read_unlock();
 146
 147         return;
 148
 149 error_rcu:
 150         rcu_read_unlock();
 151 error:
 152         dev->stats.rx_errors++;
 153         kfree_skb(skb);
 154 }
 155
 156 static void l2tp_eth_delete(struct l2tp_session *session)
 157 {
 158         struct l2tp_eth_sess *spriv;
 159         struct net_device *dev;
 160
 161         if (session) {
 162                 spriv = l2tp_session_priv(session);
 163
 164                 rtnl_lock();
 165                 dev = rtnl_dereference(spriv->dev);
 166                 if (dev) {
 167                         unregister_netdevice(dev);
 168                         rtnl_unlock();
 169                         module_put(THIS_MODULE);
 170                 } else {
 171                         rtnl_unlock();
 172                 }
 173         }
 174 }
 175
 176 #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
 177 static void l2tp_eth_show(struct seq_file *m, void *arg)
 178 {
 179         struct l2tp_session *session = arg;
 180         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 181         struct net_device *dev;
 182
 183         rcu_read_lock();
 184         dev = rcu_dereference(spriv->dev);
 185         if (!dev) {
 186                 rcu_read_unlock();
 187                 return;
 188         }
 189         dev_hold(dev);
 190         rcu_read_unlock();
 191
 192         seq_printf(m, "   interface %s\n", dev->name);
 193
 194         dev_put(dev);
 195 }
 196 #endif
 197
 198 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 199                            u32 session_id, u32 peer_session_id,
 200                            struct l2tp_session_cfg *cfg)
 201 {
 202         struct net_device *dev;
 203         char name[IFNAMSIZ];
 204         struct l2tp_session *session;
 205         struct l2tp_eth *priv;
 206         struct l2tp_eth_sess *spriv;
 207         int rc;
 208
 209         if (cfg->ifname) {
 210                 dev = dev_get_by_name(net, cfg->ifname);
 211                 if (dev) {
 212                         dev_put(dev);
 213                         rc = -EEXIST;
 214                         goto err;
 215                 }
 216                 strlcpy(name, cfg->ifname, IFNAMSIZ);
 217         } else
 218                 strcpy(name, L2TP_ETH_DEV_NAME);
 219
 220         session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 221                                       peer_session_id, cfg);
 222         if (IS_ERR(session)) {
 223                 rc = PTR_ERR(session);
 224                 goto err;
 225         }
 226
 227         dev = alloc_netdev(sizeof(*priv), name, l2tp_eth_dev_setup);
 228         if (!dev) {
 229                 rc = -ENOMEM;
 230                 goto err_sess;
 231         }
 232
 233         dev_net_set(dev, net);
 234         if (session->mtu == 0)
 235                 session->mtu = dev->mtu - session->hdr_len;
 236         dev->mtu = session->mtu;
 237         dev->needed_headroom += session->hdr_len;
 238
 239         priv = netdev_priv(dev);
 240         priv->dev = dev;
 241         priv->session = session;
 242
 243         priv->tunnel_sock = tunnel->sock;
 244         session->recv_skb = l2tp_eth_dev_recv;
 245         session->session_close = l2tp_eth_delete;
 246 #if defined(CONFIG_L2TP_DEBUGFS) || defined(CONFIG_L2TP_DEBUGFS_MODULE)
 247         session->show = l2tp_eth_show;
 248 #endif
 249
 250         spriv = l2tp_session_priv(session);
 251
 252         l2tp_session_inc_refcount(session);
 253
 254         rtnl_lock();
 255
 256         /* Register both device and session while holding the rtnl lock. This
 257          * ensures that l2tp_eth_delete() will see that there's a device to
 258          * unregister, even if it happened to run before we assign spriv->dev.
 259          */
 260         rc = l2tp_session_register(session, tunnel);
 261         if (rc < 0) {
 262                 rtnl_unlock();
 263                 goto err_sess_dev;
 264         }
 265
 266         rc = register_netdevice(dev);
 267         if (rc < 0) {
 268                 rtnl_unlock();
 269                 l2tp_session_delete(session);
 270                 l2tp_session_dec_refcount(session);
 271                 free_netdev(dev);
 272
 273                 return rc;
 274         }
 275
 276         strlcpy(session->ifname, dev->name, IFNAMSIZ);
 277         rcu_assign_pointer(spriv->dev, dev);
 278
 279         rtnl_unlock();
 280
 281         l2tp_session_dec_refcount(session);
 282
 283         __module_get(THIS_MODULE);
 284
 285         return 0;
 286
 287 err_sess_dev:
 288         l2tp_session_dec_refcount(session);
 289         free_netdev(dev);
 290 err_sess:
 291         kfree(session);
 292 err:
 293         return rc;
 294 }
 295
 296
 297 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 298         .session_create = l2tp_eth_create,
 299         .session_delete = l2tp_session_delete,
 300 };
 301
 302
 303 static int __init l2tp_eth_init(void)
 304 {
 305         int err = 0;
 306
 307         err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 308         if (err)
 309                 goto err;
 310
 311         printk(KERN_INFO "L2TP ethernet pseudowire support (L2TPv3)\n");
 312
 313         return 0;
 314
 315 err:
 316         return err;
 317 }
 318
 319 static void __exit l2tp_eth_exit(void)
 320 {
 321         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 322 }
 323
 324 module_init(l2tp_eth_init);
 325 module_exit(l2tp_eth_exit);
 326
 327 MODULE_LICENSE("GPL");
 328 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 329 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 330 MODULE_VERSION("1.0");