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       *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         dev_put(dev);
  76 }
  77
  78 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
  79 {
  80         struct l2tp_eth *priv = netdev_priv(dev);
  81         struct l2tp_session *session = priv->session;
  82         unsigned int len = skb->len;
  83         int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
  84
  85         if (likely(ret == NET_XMIT_SUCCESS)) {
  86                 atomic_long_add(len, &priv->tx_bytes);
  87                 atomic_long_inc(&priv->tx_packets);
  88         } else {
  89                 atomic_long_inc(&priv->tx_dropped);
  90         }
  91         return NETDEV_TX_OK;
  92 }
  93
  94 static void l2tp_eth_get_stats64(struct net_device *dev,
  95                                  struct rtnl_link_stats64 *stats)
  96 {
  97         struct l2tp_eth *priv = netdev_priv(dev);
  98
  99         stats->tx_bytes   = (unsigned long) atomic_long_read(&priv->tx_bytes);
 100         stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets);
 101         stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped);
 102         stats->rx_bytes   = (unsigned long) atomic_long_read(&priv->rx_bytes);
 103         stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets);
 104         stats->rx_errors  = (unsigned long) atomic_long_read(&priv->rx_errors);
 105
 106 }
 107
 108 static const struct net_device_ops l2tp_eth_netdev_ops = {
 109         .ndo_init               = l2tp_eth_dev_init,
 110         .ndo_uninit             = l2tp_eth_dev_uninit,
 111         .ndo_start_xmit         = l2tp_eth_dev_xmit,
 112         .ndo_get_stats64        = l2tp_eth_get_stats64,
 113         .ndo_set_mac_address    = eth_mac_addr,
 114 };
 115
 116 static struct device_type l2tpeth_type = {
 117         .name = "l2tpeth",
 118 };
 119
 120 static void l2tp_eth_dev_setup(struct net_device *dev)
 121 {
 122         SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 123         ether_setup(dev);
 124         dev->priv_flags         &= ~IFF_TX_SKB_SHARING;
 125         dev->features           |= NETIF_F_LLTX;
 126         dev->netdev_ops         = &l2tp_eth_netdev_ops;
 127         dev->needs_free_netdev  = true;
 128 }
 129
 130 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 131 {
 132         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 133         struct net_device *dev = spriv->dev;
 134         struct l2tp_eth *priv = netdev_priv(dev);
 135
 136         if (session->debug & L2TP_MSG_DATA) {
 137                 unsigned int length;
 138
 139                 length = min(32u, skb->len);
 140                 if (!pskb_may_pull(skb, length))
 141                         goto error;
 142
 143                 pr_debug("%s: eth recv\n", session->name);
 144                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 145         }
 146
 147         if (!pskb_may_pull(skb, ETH_HLEN))
 148                 goto error;
 149
 150         secpath_reset(skb);
 151
 152         /* checksums verified by L2TP */
 153         skb->ip_summed = CHECKSUM_NONE;
 154
 155         skb_dst_drop(skb);
 156         nf_reset(skb);
 157
 158         if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 159                 atomic_long_inc(&priv->rx_packets);
 160                 atomic_long_add(data_len, &priv->rx_bytes);
 161         } else {
 162                 atomic_long_inc(&priv->rx_errors);
 163         }
 164         return;
 165
 166 error:
 167         atomic_long_inc(&priv->rx_errors);
 168         kfree_skb(skb);
 169 }
 170
 171 static void l2tp_eth_delete(struct l2tp_session *session)
 172 {
 173         struct l2tp_eth_sess *spriv;
 174         struct net_device *dev;
 175
 176         if (session) {
 177                 spriv = l2tp_session_priv(session);
 178                 dev = spriv->dev;
 179                 if (dev) {
 180                         unregister_netdev(dev);
 181                         spriv->dev = NULL;
 182                         module_put(THIS_MODULE);
 183                 }
 184         }
 185 }
 186
 187 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 188 static void l2tp_eth_show(struct seq_file *m, void *arg)
 189 {
 190         struct l2tp_session *session = arg;
 191         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 192         struct net_device *dev = spriv->dev;
 193
 194         seq_printf(m, "   interface %s\n", dev->name);
 195 }
 196 #endif
 197
 198 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 199                                 struct l2tp_session *session,
 200                                 struct net_device *dev)
 201 {
 202         unsigned int overhead = 0;
 203         struct dst_entry *dst;
 204         u32 l3_overhead = 0;
 205
 206         /* if the encap is UDP, account for UDP header size */
 207         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 208                 overhead += sizeof(struct udphdr);
 209                 dev->needed_headroom += sizeof(struct udphdr);
 210         }
 211         if (session->mtu != 0) {
 212                 dev->mtu = session->mtu;
 213                 dev->needed_headroom += session->hdr_len;
 214                 return;
 215         }
 216         lock_sock(tunnel->sock);
 217         l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
 218         release_sock(tunnel->sock);
 219         if (l3_overhead == 0) {
 220                 /* L3 Overhead couldn't be identified, this could be
 221                  * because tunnel->sock was NULL or the socket's
 222                  * address family was not IPv4 or IPv6,
 223                  * dev mtu stays at 1500.
 224                  */
 225                 return;
 226         }
 227         /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
 228          * UDP overhead, if any, was already factored in above.
 229          */
 230         overhead += session->hdr_len + ETH_HLEN + l3_overhead;
 231
 232         /* If PMTU discovery was enabled, use discovered MTU on L2TP device */
 233         dst = sk_dst_get(tunnel->sock);
 234         if (dst) {
 235                 /* dst_mtu will use PMTU if found, else fallback to intf MTU */
 236                 u32 pmtu = dst_mtu(dst);
 237
 238                 if (pmtu != 0)
 239                         dev->mtu = pmtu;
 240                 dst_release(dst);
 241         }
 242         session->mtu = dev->mtu - overhead;
 243         dev->mtu = session->mtu;
 244         dev->needed_headroom += session->hdr_len;
 245 }
 246
 247 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 248                            u32 session_id, u32 peer_session_id,
 249                            struct l2tp_session_cfg *cfg)
 250 {
 251         unsigned char name_assign_type;
 252         struct net_device *dev;
 253         char name[IFNAMSIZ];
 254         struct l2tp_session *session;
 255         struct l2tp_eth *priv;
 256         struct l2tp_eth_sess *spriv;
 257         int rc;
 258
 259         if (cfg->ifname) {
 260                 strlcpy(name, cfg->ifname, IFNAMSIZ);
 261                 name_assign_type = NET_NAME_USER;
 262         } else {
 263                 strcpy(name, L2TP_ETH_DEV_NAME);
 264                 name_assign_type = NET_NAME_ENUM;
 265         }
 266
 267         session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 268                                       peer_session_id, cfg);
 269         if (IS_ERR(session)) {
 270                 rc = PTR_ERR(session);
 271                 goto out;
 272         }
 273
 274         dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
 275                            l2tp_eth_dev_setup);
 276         if (!dev) {
 277                 rc = -ENOMEM;
 278                 goto out_del_session;
 279         }
 280
 281         dev_net_set(dev, net);
 282         dev->min_mtu = 0;
 283         dev->max_mtu = ETH_MAX_MTU;
 284         l2tp_eth_adjust_mtu(tunnel, session, dev);
 285
 286         priv = netdev_priv(dev);
 287         priv->dev = dev;
 288         priv->session = session;
 289
 290         priv->tunnel_sock = tunnel->sock;
 291         session->recv_skb = l2tp_eth_dev_recv;
 292         session->session_close = l2tp_eth_delete;
 293 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 294         session->show = l2tp_eth_show;
 295 #endif
 296
 297         spriv = l2tp_session_priv(session);
 298         spriv->dev = dev;
 299
 300         rc = register_netdev(dev);
 301         if (rc < 0)
 302                 goto out_del_dev;
 303
 304         __module_get(THIS_MODULE);
 305         /* Must be done after register_netdev() */
 306         strlcpy(session->ifname, dev->name, IFNAMSIZ);
 307
 308         dev_hold(dev);
 309
 310         return 0;
 311
 312 out_del_dev:
 313         free_netdev(dev);
 314         spriv->dev = NULL;
 315 out_del_session:
 316         l2tp_session_delete(session);
 317 out:
 318         return rc;
 319 }
 320
 321
 322 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 323         .session_create = l2tp_eth_create,
 324         .session_delete = l2tp_session_delete,
 325 };
 326
 327
 328 static int __init l2tp_eth_init(void)
 329 {
 330         int err = 0;
 331
 332         err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 333         if (err)
 334                 goto err;
 335
 336         pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
 337
 338         return 0;
 339
 340 err:
 341         return err;
 342 }
 343
 344 static void __exit l2tp_eth_exit(void)
 345 {
 346         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 347 }
 348
 349 module_init(l2tp_eth_init);
 350 module_exit(l2tp_eth_exit);
 351
 352 MODULE_LICENSE("GPL");
 353 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 354 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 355 MODULE_VERSION("1.0");
 356 MODULE_ALIAS_L2TP_PWTYPE(5);