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 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS) 203 static void l2tp_eth_show(struct seq_file *m, void *arg) 204 { 205 struct l2tp_session *session = arg; 206 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 207 struct net_device *dev; 208 209 rcu_read_lock(); 210 dev = rcu_dereference(spriv->dev); 211 if (!dev) { 212 rcu_read_unlock(); 213 return; 214 } 215 dev_hold(dev); 216 rcu_read_unlock(); 217 218 seq_printf(m, " interface %s\n", dev->name); 219 220 dev_put(dev); 221 } 222 #endif 223 224 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 225 struct l2tp_session *session, 226 struct net_device *dev) 227 { 228 unsigned int overhead = 0; 229 struct dst_entry *dst; 230 u32 l3_overhead = 0; 231 232 /* if the encap is UDP, account for UDP header size */ 233 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 234 overhead += sizeof(struct udphdr); 235 dev->needed_headroom += sizeof(struct udphdr); 236 } 237 if (session->mtu != 0) { 238 dev->mtu = session->mtu; 239 dev->needed_headroom += session->hdr_len; 240 return; 241 } 242 lock_sock(tunnel->sock); 243 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 244 release_sock(tunnel->sock); 245 if (l3_overhead == 0) { 246 /* L3 Overhead couldn't be identified, this could be 247 * because tunnel->sock was NULL or the socket's 248 * address family was not IPv4 or IPv6, 249 * dev mtu stays at 1500. 250 */ 251 return; 252 } 253 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 254 * UDP overhead, if any, was already factored in above. 255 */ 256 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 257 258 /* If PMTU discovery was enabled, use discovered MTU on L2TP device */ 259 dst = sk_dst_get(tunnel->sock); 260 if (dst) { 261 /* dst_mtu will use PMTU if found, else fallback to intf MTU */ 262 u32 pmtu = dst_mtu(dst); 263 264 if (pmtu != 0) 265 dev->mtu = pmtu; 266 dst_release(dst); 267 } 268 session->mtu = dev->mtu - overhead; 269 dev->mtu = session->mtu; 270 dev->needed_headroom += session->hdr_len; 271 } 272 273 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 274 u32 session_id, u32 peer_session_id, 275 struct l2tp_session_cfg *cfg) 276 { 277 unsigned char name_assign_type; 278 struct net_device *dev; 279 char name[IFNAMSIZ]; 280 struct l2tp_session *session; 281 struct l2tp_eth *priv; 282 struct l2tp_eth_sess *spriv; 283 int rc; 284 285 if (cfg->ifname) { 286 strlcpy(name, cfg->ifname, IFNAMSIZ); 287 name_assign_type = NET_NAME_USER; 288 } else { 289 strcpy(name, L2TP_ETH_DEV_NAME); 290 name_assign_type = NET_NAME_ENUM; 291 } 292 293 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 294 peer_session_id, cfg); 295 if (IS_ERR(session)) { 296 rc = PTR_ERR(session); 297 goto err; 298 } 299 300 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 301 l2tp_eth_dev_setup); 302 if (!dev) { 303 rc = -ENOMEM; 304 goto err_sess; 305 } 306 307 dev_net_set(dev, net); 308 dev->min_mtu = 0; 309 dev->max_mtu = ETH_MAX_MTU; 310 l2tp_eth_adjust_mtu(tunnel, session, dev); 311 312 priv = netdev_priv(dev); 313 priv->session = session; 314 315 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); 322 323 l2tp_session_inc_refcount(session); 324 325 rtnl_lock(); 326 327 /* Register both device and session while holding the rtnl lock. This 328 * ensures that l2tp_eth_delete() will see that there's a device to 329 * unregister, even if it happened to run before we assign spriv->dev. 330 */ 331 rc = l2tp_session_register(session, tunnel); 332 if (rc < 0) { 333 rtnl_unlock(); 334 goto err_sess_dev; 335 } 336 337 rc = register_netdevice(dev); 338 if (rc < 0) { 339 rtnl_unlock(); 340 l2tp_session_delete(session); 341 l2tp_session_dec_refcount(session); 342 free_netdev(dev); 343 344 return rc; 345 } 346 347 strlcpy(session->ifname, dev->name, IFNAMSIZ); 348 rcu_assign_pointer(spriv->dev, dev); 349 350 rtnl_unlock(); 351 352 l2tp_session_dec_refcount(session); 353 354 __module_get(THIS_MODULE); 355 356 return 0; 357 358 err_sess_dev: 359 l2tp_session_dec_refcount(session); 360 free_netdev(dev); 361 err_sess: 362 kfree(session); 363 err: 364 return rc; 365 } 366 367 368 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 369 .session_create = l2tp_eth_create, 370 .session_delete = l2tp_session_delete, 371 }; 372 373 374 static int __init l2tp_eth_init(void) 375 { 376 int err = 0; 377 378 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 379 if (err) 380 goto err; 381 382 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 383 384 return 0; 385 386 err: 387 return err; 388 } 389 390 static void __exit l2tp_eth_exit(void) 391 { 392 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 393 } 394 395 module_init(l2tp_eth_init); 396 module_exit(l2tp_eth_exit); 397 398 MODULE_LICENSE("GPL"); 399 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 400 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 401 MODULE_VERSION("1.0"); 402 MODULE_ALIAS_L2TP_PWTYPE(5); 403