1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * L2TPv3 ethernet pseudowire driver 4 * 5 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 6 */ 7 8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 9 10 #include <linux/module.h> 11 #include <linux/skbuff.h> 12 #include <linux/socket.h> 13 #include <linux/hash.h> 14 #include <linux/l2tp.h> 15 #include <linux/in.h> 16 #include <linux/etherdevice.h> 17 #include <linux/spinlock.h> 18 #include <net/sock.h> 19 #include <net/ip.h> 20 #include <net/icmp.h> 21 #include <net/udp.h> 22 #include <net/inet_common.h> 23 #include <net/inet_hashtables.h> 24 #include <net/tcp_states.h> 25 #include <net/protocol.h> 26 #include <net/xfrm.h> 27 #include <net/net_namespace.h> 28 #include <net/netns/generic.h> 29 #include <linux/ip.h> 30 #include <linux/ipv6.h> 31 #include <linux/udp.h> 32 33 #include "l2tp_core.h" 34 35 /* Default device name. May be overridden by name specified by user */ 36 #define L2TP_ETH_DEV_NAME "l2tpeth%d" 37 38 /* via netdev_priv() */ 39 struct l2tp_eth { 40 struct l2tp_session *session; 41 atomic_long_t tx_bytes; 42 atomic_long_t tx_packets; 43 atomic_long_t tx_dropped; 44 atomic_long_t rx_bytes; 45 atomic_long_t rx_packets; 46 atomic_long_t rx_errors; 47 }; 48 49 /* via l2tp_session_priv() */ 50 struct l2tp_eth_sess { 51 struct net_device __rcu *dev; 52 }; 53 54 55 static int l2tp_eth_dev_init(struct net_device *dev) 56 { 57 eth_hw_addr_random(dev); 58 eth_broadcast_addr(dev->broadcast); 59 netdev_lockdep_set_classes(dev); 60 61 return 0; 62 } 63 64 static void l2tp_eth_dev_uninit(struct net_device *dev) 65 { 66 struct l2tp_eth *priv = netdev_priv(dev); 67 struct l2tp_eth_sess *spriv; 68 69 spriv = l2tp_session_priv(priv->session); 70 RCU_INIT_POINTER(spriv->dev, NULL); 71 /* No need for synchronize_net() here. We're called by 72 * unregister_netdev*(), which does the synchronisation for us. 73 */ 74 } 75 76 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev) 77 { 78 struct l2tp_eth *priv = netdev_priv(dev); 79 struct l2tp_session *session = priv->session; 80 unsigned int len = skb->len; 81 int ret = l2tp_xmit_skb(session, skb, session->hdr_len); 82 83 if (likely(ret == NET_XMIT_SUCCESS)) { 84 atomic_long_add(len, &priv->tx_bytes); 85 atomic_long_inc(&priv->tx_packets); 86 } else { 87 atomic_long_inc(&priv->tx_dropped); 88 } 89 return NETDEV_TX_OK; 90 } 91 92 static void l2tp_eth_get_stats64(struct net_device *dev, 93 struct rtnl_link_stats64 *stats) 94 { 95 struct l2tp_eth *priv = netdev_priv(dev); 96 97 stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes); 98 stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets); 99 stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped); 100 stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes); 101 stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets); 102 stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors); 103 104 } 105 106 static const struct net_device_ops l2tp_eth_netdev_ops = { 107 .ndo_init = l2tp_eth_dev_init, 108 .ndo_uninit = l2tp_eth_dev_uninit, 109 .ndo_start_xmit = l2tp_eth_dev_xmit, 110 .ndo_get_stats64 = l2tp_eth_get_stats64, 111 .ndo_set_mac_address = eth_mac_addr, 112 }; 113 114 static struct device_type l2tpeth_type = { 115 .name = "l2tpeth", 116 }; 117 118 static void l2tp_eth_dev_setup(struct net_device *dev) 119 { 120 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 121 ether_setup(dev); 122 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 123 dev->features |= NETIF_F_LLTX; 124 dev->netdev_ops = &l2tp_eth_netdev_ops; 125 dev->needs_free_netdev = true; 126 } 127 128 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 129 { 130 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 131 struct net_device *dev; 132 struct l2tp_eth *priv; 133 134 if (session->debug & L2TP_MSG_DATA) { 135 unsigned int length; 136 137 length = min(32u, skb->len); 138 if (!pskb_may_pull(skb, length)) 139 goto error; 140 141 pr_debug("%s: eth recv\n", session->name); 142 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 143 } 144 145 if (!pskb_may_pull(skb, ETH_HLEN)) 146 goto error; 147 148 secpath_reset(skb); 149 150 /* checksums verified by L2TP */ 151 skb->ip_summed = CHECKSUM_NONE; 152 153 skb_dst_drop(skb); 154 nf_reset(skb); 155 156 rcu_read_lock(); 157 dev = rcu_dereference(spriv->dev); 158 if (!dev) 159 goto error_rcu; 160 161 priv = netdev_priv(dev); 162 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 163 atomic_long_inc(&priv->rx_packets); 164 atomic_long_add(data_len, &priv->rx_bytes); 165 } else { 166 atomic_long_inc(&priv->rx_errors); 167 } 168 rcu_read_unlock(); 169 170 return; 171 172 error_rcu: 173 rcu_read_unlock(); 174 error: 175 kfree_skb(skb); 176 } 177 178 static void l2tp_eth_delete(struct l2tp_session *session) 179 { 180 struct l2tp_eth_sess *spriv; 181 struct net_device *dev; 182 183 if (session) { 184 spriv = l2tp_session_priv(session); 185 186 rtnl_lock(); 187 dev = rtnl_dereference(spriv->dev); 188 if (dev) { 189 unregister_netdevice(dev); 190 rtnl_unlock(); 191 module_put(THIS_MODULE); 192 } else { 193 rtnl_unlock(); 194 } 195 } 196 } 197 198 static void l2tp_eth_show(struct seq_file *m, void *arg) 199 { 200 struct l2tp_session *session = arg; 201 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 202 struct net_device *dev; 203 204 rcu_read_lock(); 205 dev = rcu_dereference(spriv->dev); 206 if (!dev) { 207 rcu_read_unlock(); 208 return; 209 } 210 dev_hold(dev); 211 rcu_read_unlock(); 212 213 seq_printf(m, " interface %s\n", dev->name); 214 215 dev_put(dev); 216 } 217 218 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 219 struct l2tp_session *session, 220 struct net_device *dev) 221 { 222 unsigned int overhead = 0; 223 u32 l3_overhead = 0; 224 u32 mtu; 225 226 /* if the encap is UDP, account for UDP header size */ 227 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 228 overhead += sizeof(struct udphdr); 229 dev->needed_headroom += sizeof(struct udphdr); 230 } 231 232 lock_sock(tunnel->sock); 233 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 234 release_sock(tunnel->sock); 235 236 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 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 250 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 251 dev->mtu = ETH_DATA_LEN - overhead; 252 else 253 dev->mtu = mtu; 254 255 dev->needed_headroom += session->hdr_len; 256 } 257 258 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 259 u32 session_id, u32 peer_session_id, 260 struct l2tp_session_cfg *cfg) 261 { 262 unsigned char name_assign_type; 263 struct net_device *dev; 264 char name[IFNAMSIZ]; 265 struct l2tp_session *session; 266 struct l2tp_eth *priv; 267 struct l2tp_eth_sess *spriv; 268 int rc; 269 270 if (cfg->ifname) { 271 strlcpy(name, cfg->ifname, IFNAMSIZ); 272 name_assign_type = NET_NAME_USER; 273 } else { 274 strcpy(name, L2TP_ETH_DEV_NAME); 275 name_assign_type = NET_NAME_ENUM; 276 } 277 278 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 279 peer_session_id, cfg); 280 if (IS_ERR(session)) { 281 rc = PTR_ERR(session); 282 goto err; 283 } 284 285 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 286 l2tp_eth_dev_setup); 287 if (!dev) { 288 rc = -ENOMEM; 289 goto err_sess; 290 } 291 292 dev_net_set(dev, net); 293 dev->min_mtu = 0; 294 dev->max_mtu = ETH_MAX_MTU; 295 l2tp_eth_adjust_mtu(tunnel, session, dev); 296 297 priv = netdev_priv(dev); 298 priv->session = session; 299 300 session->recv_skb = l2tp_eth_dev_recv; 301 session->session_close = l2tp_eth_delete; 302 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 303 session->show = l2tp_eth_show; 304 305 spriv = l2tp_session_priv(session); 306 307 l2tp_session_inc_refcount(session); 308 309 rtnl_lock(); 310 311 /* Register both device and session while holding the rtnl lock. This 312 * ensures that l2tp_eth_delete() will see that there's a device to 313 * unregister, even if it happened to run before we assign spriv->dev. 314 */ 315 rc = l2tp_session_register(session, tunnel); 316 if (rc < 0) { 317 rtnl_unlock(); 318 goto err_sess_dev; 319 } 320 321 rc = register_netdevice(dev); 322 if (rc < 0) { 323 rtnl_unlock(); 324 l2tp_session_delete(session); 325 l2tp_session_dec_refcount(session); 326 free_netdev(dev); 327 328 return rc; 329 } 330 331 strlcpy(session->ifname, dev->name, IFNAMSIZ); 332 rcu_assign_pointer(spriv->dev, dev); 333 334 rtnl_unlock(); 335 336 l2tp_session_dec_refcount(session); 337 338 __module_get(THIS_MODULE); 339 340 return 0; 341 342 err_sess_dev: 343 l2tp_session_dec_refcount(session); 344 free_netdev(dev); 345 err_sess: 346 kfree(session); 347 err: 348 return rc; 349 } 350 351 352 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 353 .session_create = l2tp_eth_create, 354 .session_delete = l2tp_session_delete, 355 }; 356 357 358 static int __init l2tp_eth_init(void) 359 { 360 int err = 0; 361 362 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 363 if (err) 364 goto err; 365 366 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 367 368 return 0; 369 370 err: 371 return err; 372 } 373 374 static void __exit l2tp_eth_exit(void) 375 { 376 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 377 } 378 379 module_init(l2tp_eth_init); 380 module_exit(l2tp_eth_exit); 381 382 MODULE_LICENSE("GPL"); 383 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 384 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 385 MODULE_VERSION("1.0"); 386 MODULE_ALIAS_L2TP_PWTYPE(5); 387