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         struct list_head        list;
  48         atomic_long_t           tx_bytes;
  49         atomic_long_t           tx_packets;
  50         atomic_long_t           tx_dropped;
  51         atomic_long_t           rx_bytes;
  52         atomic_long_t           rx_packets;
  53         atomic_long_t           rx_errors;
  54 };
  55
  56 /* via l2tp_session_priv() */
  57 struct l2tp_eth_sess {
  58         struct net_device       *dev;
  59 };
  60
  61 /* per-net private data for this module */
  62 static unsigned int l2tp_eth_net_id;
  63 struct l2tp_eth_net {
  64         struct list_head l2tp_eth_dev_list;
  65         spinlock_t l2tp_eth_lock;
  66 };
  67
  68 static inline struct l2tp_eth_net *l2tp_eth_pernet(struct net *net)
  69 {
  70         return net_generic(net, l2tp_eth_net_id);
  71 }
  72
  73 static int l2tp_eth_dev_init(struct net_device *dev)
  74 {
  75         struct l2tp_eth *priv = netdev_priv(dev);
  76
  77         priv->dev = dev;
  78         eth_hw_addr_random(dev);
  79         eth_broadcast_addr(dev->broadcast);
  80         netdev_lockdep_set_classes(dev);
  81
  82         return 0;
  83 }
  84
  85 static void l2tp_eth_dev_uninit(struct net_device *dev)
  86 {
  87         struct l2tp_eth *priv = netdev_priv(dev);
  88         struct l2tp_eth_net *pn = l2tp_eth_pernet(dev_net(dev));
  89
  90         spin_lock(&pn->l2tp_eth_lock);
  91         list_del_init(&priv->list);
  92         spin_unlock(&pn->l2tp_eth_lock);
  93         dev_put(dev);
  94 }
  95
  96 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
  97 {
  98         struct l2tp_eth *priv = netdev_priv(dev);
  99         struct l2tp_session *session = priv->session;
 100         unsigned int len = skb->len;
 101         int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
 102
 103         if (likely(ret == NET_XMIT_SUCCESS)) {
 104                 atomic_long_add(len, &priv->tx_bytes);
 105                 atomic_long_inc(&priv->tx_packets);
 106         } else {
 107                 atomic_long_inc(&priv->tx_dropped);
 108         }
 109         return NETDEV_TX_OK;
 110 }
 111
 112 static void l2tp_eth_get_stats64(struct net_device *dev,
 113                                  struct rtnl_link_stats64 *stats)
 114 {
 115         struct l2tp_eth *priv = netdev_priv(dev);
 116
 117         stats->tx_bytes   = atomic_long_read(&priv->tx_bytes);
 118         stats->tx_packets = atomic_long_read(&priv->tx_packets);
 119         stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
 120         stats->rx_bytes   = atomic_long_read(&priv->rx_bytes);
 121         stats->rx_packets = atomic_long_read(&priv->rx_packets);
 122         stats->rx_errors  = atomic_long_read(&priv->rx_errors);
 123 }
 124
 125 static const struct net_device_ops l2tp_eth_netdev_ops = {
 126         .ndo_init               = l2tp_eth_dev_init,
 127         .ndo_uninit             = l2tp_eth_dev_uninit,
 128         .ndo_start_xmit         = l2tp_eth_dev_xmit,
 129         .ndo_get_stats64        = l2tp_eth_get_stats64,
 130         .ndo_set_mac_address    = eth_mac_addr,
 131 };
 132
 133 static struct device_type l2tpeth_type = {
 134         .name = "l2tpeth",
 135 };
 136
 137 static void l2tp_eth_dev_setup(struct net_device *dev)
 138 {
 139         SET_NETDEV_DEVTYPE(dev, &l2tpeth_type);
 140         ether_setup(dev);
 141         dev->priv_flags         &= ~IFF_TX_SKB_SHARING;
 142         dev->features           |= NETIF_F_LLTX;
 143         dev->netdev_ops         = &l2tp_eth_netdev_ops;
 144         dev->destructor         = free_netdev;
 145 }
 146
 147 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
 148 {
 149         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 150         struct net_device *dev = spriv->dev;
 151         struct l2tp_eth *priv = netdev_priv(dev);
 152
 153         if (session->debug & L2TP_MSG_DATA) {
 154                 unsigned int length;
 155
 156                 length = min(32u, skb->len);
 157                 if (!pskb_may_pull(skb, length))
 158                         goto error;
 159
 160                 pr_debug("%s: eth recv\n", session->name);
 161                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 162         }
 163
 164         if (!pskb_may_pull(skb, ETH_HLEN))
 165                 goto error;
 166
 167         secpath_reset(skb);
 168
 169         /* checksums verified by L2TP */
 170         skb->ip_summed = CHECKSUM_NONE;
 171
 172         skb_dst_drop(skb);
 173         nf_reset(skb);
 174
 175         if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) {
 176                 atomic_long_inc(&priv->rx_packets);
 177                 atomic_long_add(data_len, &priv->rx_bytes);
 178         } else {
 179                 atomic_long_inc(&priv->rx_errors);
 180         }
 181         return;
 182
 183 error:
 184         atomic_long_inc(&priv->rx_errors);
 185         kfree_skb(skb);
 186 }
 187
 188 static void l2tp_eth_delete(struct l2tp_session *session)
 189 {
 190         struct l2tp_eth_sess *spriv;
 191         struct net_device *dev;
 192
 193         if (session) {
 194                 spriv = l2tp_session_priv(session);
 195                 dev = spriv->dev;
 196                 if (dev) {
 197                         unregister_netdev(dev);
 198                         spriv->dev = NULL;
 199                         module_put(THIS_MODULE);
 200                 }
 201         }
 202 }
 203
 204 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 205 static void l2tp_eth_show(struct seq_file *m, void *arg)
 206 {
 207         struct l2tp_session *session = arg;
 208         struct l2tp_eth_sess *spriv = l2tp_session_priv(session);
 209         struct net_device *dev = spriv->dev;
 210
 211         seq_printf(m, "   interface %s\n", dev->name);
 212 }
 213 #endif
 214
 215 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 216                                 struct l2tp_session *session,
 217                                 struct net_device *dev)
 218 {
 219         unsigned int overhead = 0;
 220         struct dst_entry *dst;
 221         u32 l3_overhead = 0;
 222
 223         /* if the encap is UDP, account for UDP header size */
 224         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 225                 overhead += sizeof(struct udphdr);
 226                 dev->needed_headroom += sizeof(struct udphdr);
 227         }
 228         if (session->mtu != 0) {
 229                 dev->mtu = session->mtu;
 230                 dev->needed_headroom += session->hdr_len;
 231                 return;
 232         }
 233         lock_sock(tunnel->sock);
 234         l3_overhead = kernel_sock_ip_overhead(tunnel->sock);
 235         release_sock(tunnel->sock);
 236         if (l3_overhead == 0) {
 237                 /* L3 Overhead couldn't be identified, this could be
 238                  * because tunnel->sock was NULL or the socket's
 239                  * address family was not IPv4 or IPv6,
 240                  * dev mtu stays at 1500.
 241                  */
 242                 return;
 243         }
 244         /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr
 245          * UDP overhead, if any, was already factored in above.
 246          */
 247         overhead += session->hdr_len + ETH_HLEN + l3_overhead;
 248
 249         /* If PMTU discovery was enabled, use discovered MTU on L2TP device */
 250         dst = sk_dst_get(tunnel->sock);
 251         if (dst) {
 252                 /* dst_mtu will use PMTU if found, else fallback to intf MTU */
 253                 u32 pmtu = dst_mtu(dst);
 254
 255                 if (pmtu != 0)
 256                         dev->mtu = pmtu;
 257                 dst_release(dst);
 258         }
 259         session->mtu = dev->mtu - overhead;
 260         dev->mtu = session->mtu;
 261         dev->needed_headroom += session->hdr_len;
 262 }
 263
 264 static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
 265 {
 266         unsigned char name_assign_type;
 267         struct net_device *dev;
 268         char name[IFNAMSIZ];
 269         struct l2tp_tunnel *tunnel;
 270         struct l2tp_session *session;
 271         struct l2tp_eth *priv;
 272         struct l2tp_eth_sess *spriv;
 273         int rc;
 274         struct l2tp_eth_net *pn;
 275
 276         tunnel = l2tp_tunnel_find(net, tunnel_id);
 277         if (!tunnel) {
 278                 rc = -ENODEV;
 279                 goto out;
 280         }
 281
 282         if (cfg->ifname) {
 283                 strlcpy(name, cfg->ifname, IFNAMSIZ);
 284                 name_assign_type = NET_NAME_USER;
 285         } else {
 286                 strcpy(name, L2TP_ETH_DEV_NAME);
 287                 name_assign_type = NET_NAME_ENUM;
 288         }
 289
 290         session = l2tp_session_create(sizeof(*spriv), tunnel, session_id,
 291                                       peer_session_id, cfg);
 292         if (IS_ERR(session)) {
 293                 rc = PTR_ERR(session);
 294                 goto out;
 295         }
 296
 297         dev = alloc_netdev(sizeof(*priv), name, name_assign_type,
 298                            l2tp_eth_dev_setup);
 299         if (!dev) {
 300                 rc = -ENOMEM;
 301                 goto out_del_session;
 302         }
 303
 304         dev_net_set(dev, net);
 305         dev->min_mtu = 0;
 306         dev->max_mtu = ETH_MAX_MTU;
 307         l2tp_eth_adjust_mtu(tunnel, session, dev);
 308
 309         priv = netdev_priv(dev);
 310         priv->dev = dev;
 311         priv->session = session;
 312         INIT_LIST_HEAD(&priv->list);
 313
 314         priv->tunnel_sock = tunnel->sock;
 315         session->recv_skb = l2tp_eth_dev_recv;
 316         session->session_close = l2tp_eth_delete;
 317 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 318         session->show = l2tp_eth_show;
 319 #endif
 320
 321         spriv = l2tp_session_priv(session);
 322         spriv->dev = dev;
 323
 324         rc = register_netdev(dev);
 325         if (rc < 0)
 326                 goto out_del_dev;
 327
 328         __module_get(THIS_MODULE);
 329         /* Must be done after register_netdev() */
 330         strlcpy(session->ifname, dev->name, IFNAMSIZ);
 331
 332         dev_hold(dev);
 333         pn = l2tp_eth_pernet(dev_net(dev));
 334         spin_lock(&pn->l2tp_eth_lock);
 335         list_add(&priv->list, &pn->l2tp_eth_dev_list);
 336         spin_unlock(&pn->l2tp_eth_lock);
 337
 338         return 0;
 339
 340 out_del_dev:
 341         free_netdev(dev);
 342         spriv->dev = NULL;
 343 out_del_session:
 344         l2tp_session_delete(session);
 345 out:
 346         return rc;
 347 }
 348
 349 static __net_init int l2tp_eth_init_net(struct net *net)
 350 {
 351         struct l2tp_eth_net *pn = net_generic(net, l2tp_eth_net_id);
 352
 353         INIT_LIST_HEAD(&pn->l2tp_eth_dev_list);
 354         spin_lock_init(&pn->l2tp_eth_lock);
 355
 356         return 0;
 357 }
 358
 359 static struct pernet_operations l2tp_eth_net_ops = {
 360         .init = l2tp_eth_init_net,
 361         .id   = &l2tp_eth_net_id,
 362         .size = sizeof(struct l2tp_eth_net),
 363 };
 364
 365
 366 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = {
 367         .session_create = l2tp_eth_create,
 368         .session_delete = l2tp_session_delete,
 369 };
 370
 371
 372 static int __init l2tp_eth_init(void)
 373 {
 374         int err = 0;
 375
 376         err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops);
 377         if (err)
 378                 goto out;
 379
 380         err = register_pernet_device(&l2tp_eth_net_ops);
 381         if (err)
 382                 goto out_unreg;
 383
 384         pr_info("L2TP ethernet pseudowire support (L2TPv3)\n");
 385
 386         return 0;
 387
 388 out_unreg:
 389         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 390 out:
 391         return err;
 392 }
 393
 394 static void __exit l2tp_eth_exit(void)
 395 {
 396         unregister_pernet_device(&l2tp_eth_net_ops);
 397         l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH);
 398 }
 399
 400 module_init(l2tp_eth_init);
 401 module_exit(l2tp_eth_exit);
 402
 403 MODULE_LICENSE("GPL");
 404 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 405 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 406 MODULE_VERSION("1.0");
 407 MODULE_ALIAS_L2TP_PWTYPE(5);