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 static int l2tp_eth_dev_init(struct net_device *dev) 55 { 56 eth_hw_addr_random(dev); 57 eth_broadcast_addr(dev->broadcast); 58 netdev_lockdep_set_classes(dev); 59 60 return 0; 61 } 62 63 static void l2tp_eth_dev_uninit(struct net_device *dev) 64 { 65 struct l2tp_eth *priv = netdev_priv(dev); 66 struct l2tp_eth_sess *spriv; 67 68 spriv = l2tp_session_priv(priv->session); 69 RCU_INIT_POINTER(spriv->dev, NULL); 70 /* No need for synchronize_net() here. We're called by 71 * unregister_netdev*(), which does the synchronisation for us. 72 */ 73 } 74 75 static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev) 76 { 77 struct l2tp_eth *priv = netdev_priv(dev); 78 struct l2tp_session *session = priv->session; 79 unsigned int len = skb->len; 80 int ret = l2tp_xmit_skb(session, skb, session->hdr_len); 81 82 if (likely(ret == NET_XMIT_SUCCESS)) { 83 atomic_long_add(len, &priv->tx_bytes); 84 atomic_long_inc(&priv->tx_packets); 85 } else { 86 atomic_long_inc(&priv->tx_dropped); 87 } 88 return NETDEV_TX_OK; 89 } 90 91 static void l2tp_eth_get_stats64(struct net_device *dev, 92 struct rtnl_link_stats64 *stats) 93 { 94 struct l2tp_eth *priv = netdev_priv(dev); 95 96 stats->tx_bytes = (unsigned long)atomic_long_read(&priv->tx_bytes); 97 stats->tx_packets = (unsigned long)atomic_long_read(&priv->tx_packets); 98 stats->tx_dropped = (unsigned long)atomic_long_read(&priv->tx_dropped); 99 stats->rx_bytes = (unsigned long)atomic_long_read(&priv->rx_bytes); 100 stats->rx_packets = (unsigned long)atomic_long_read(&priv->rx_packets); 101 stats->rx_errors = (unsigned long)atomic_long_read(&priv->rx_errors); 102 } 103 104 static const struct net_device_ops l2tp_eth_netdev_ops = { 105 .ndo_init = l2tp_eth_dev_init, 106 .ndo_uninit = l2tp_eth_dev_uninit, 107 .ndo_start_xmit = l2tp_eth_dev_xmit, 108 .ndo_get_stats64 = l2tp_eth_get_stats64, 109 .ndo_set_mac_address = eth_mac_addr, 110 }; 111 112 static struct device_type l2tpeth_type = { 113 .name = "l2tpeth", 114 }; 115 116 static void l2tp_eth_dev_setup(struct net_device *dev) 117 { 118 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 119 ether_setup(dev); 120 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 121 dev->features |= NETIF_F_LLTX; 122 dev->netdev_ops = &l2tp_eth_netdev_ops; 123 dev->needs_free_netdev = true; 124 } 125 126 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 127 { 128 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 129 struct net_device *dev; 130 struct l2tp_eth *priv; 131 132 if (session->debug & L2TP_MSG_DATA) { 133 unsigned int length; 134 135 length = min(32u, skb->len); 136 if (!pskb_may_pull(skb, length)) 137 goto error; 138 139 pr_debug("%s: eth recv\n", session->name); 140 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 141 } 142 143 if (!pskb_may_pull(skb, ETH_HLEN)) 144 goto error; 145 146 secpath_reset(skb); 147 148 /* checksums verified by L2TP */ 149 skb->ip_summed = CHECKSUM_NONE; 150 151 skb_dst_drop(skb); 152 nf_reset_ct(skb); 153 154 rcu_read_lock(); 155 dev = rcu_dereference(spriv->dev); 156 if (!dev) 157 goto error_rcu; 158 159 priv = netdev_priv(dev); 160 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 161 atomic_long_inc(&priv->rx_packets); 162 atomic_long_add(data_len, &priv->rx_bytes); 163 } else { 164 atomic_long_inc(&priv->rx_errors); 165 } 166 rcu_read_unlock(); 167 168 return; 169 170 error_rcu: 171 rcu_read_unlock(); 172 error: 173 kfree_skb(skb); 174 } 175 176 static void l2tp_eth_delete(struct l2tp_session *session) 177 { 178 struct l2tp_eth_sess *spriv; 179 struct net_device *dev; 180 181 if (session) { 182 spriv = l2tp_session_priv(session); 183 184 rtnl_lock(); 185 dev = rtnl_dereference(spriv->dev); 186 if (dev) { 187 unregister_netdevice(dev); 188 rtnl_unlock(); 189 module_put(THIS_MODULE); 190 } else { 191 rtnl_unlock(); 192 } 193 } 194 } 195 196 static void l2tp_eth_show(struct seq_file *m, void *arg) 197 { 198 struct l2tp_session *session = arg; 199 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 200 struct net_device *dev; 201 202 rcu_read_lock(); 203 dev = rcu_dereference(spriv->dev); 204 if (!dev) { 205 rcu_read_unlock(); 206 return; 207 } 208 dev_hold(dev); 209 rcu_read_unlock(); 210 211 seq_printf(m, " interface %s\n", dev->name); 212 213 dev_put(dev); 214 } 215 216 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 217 struct l2tp_session *session, 218 struct net_device *dev) 219 { 220 unsigned int overhead = 0; 221 u32 l3_overhead = 0; 222 u32 mtu; 223 224 /* if the encap is UDP, account for UDP header size */ 225 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 226 overhead += sizeof(struct udphdr); 227 dev->needed_headroom += sizeof(struct udphdr); 228 } 229 230 lock_sock(tunnel->sock); 231 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 232 release_sock(tunnel->sock); 233 234 if (l3_overhead == 0) { 235 /* L3 Overhead couldn't be identified, this could be 236 * because tunnel->sock was NULL or the socket's 237 * address family was not IPv4 or IPv6, 238 * dev mtu stays at 1500. 239 */ 240 return; 241 } 242 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 243 * UDP overhead, if any, was already factored in above. 244 */ 245 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 246 247 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 248 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 249 dev->mtu = ETH_DATA_LEN - overhead; 250 else 251 dev->mtu = mtu; 252 253 dev->needed_headroom += session->hdr_len; 254 } 255 256 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 257 u32 session_id, u32 peer_session_id, 258 struct l2tp_session_cfg *cfg) 259 { 260 unsigned char name_assign_type; 261 struct net_device *dev; 262 char name[IFNAMSIZ]; 263 struct l2tp_session *session; 264 struct l2tp_eth *priv; 265 struct l2tp_eth_sess *spriv; 266 int rc; 267 268 if (cfg->ifname) { 269 strlcpy(name, cfg->ifname, IFNAMSIZ); 270 name_assign_type = NET_NAME_USER; 271 } else { 272 strcpy(name, L2TP_ETH_DEV_NAME); 273 name_assign_type = NET_NAME_ENUM; 274 } 275 276 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 277 peer_session_id, cfg); 278 if (IS_ERR(session)) { 279 rc = PTR_ERR(session); 280 goto err; 281 } 282 283 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 284 l2tp_eth_dev_setup); 285 if (!dev) { 286 rc = -ENOMEM; 287 goto err_sess; 288 } 289 290 dev_net_set(dev, net); 291 dev->min_mtu = 0; 292 dev->max_mtu = ETH_MAX_MTU; 293 l2tp_eth_adjust_mtu(tunnel, session, dev); 294 295 priv = netdev_priv(dev); 296 priv->session = session; 297 298 session->recv_skb = l2tp_eth_dev_recv; 299 session->session_close = l2tp_eth_delete; 300 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 301 session->show = l2tp_eth_show; 302 303 spriv = l2tp_session_priv(session); 304 305 l2tp_session_inc_refcount(session); 306 307 rtnl_lock(); 308 309 /* Register both device and session while holding the rtnl lock. This 310 * ensures that l2tp_eth_delete() will see that there's a device to 311 * unregister, even if it happened to run before we assign spriv->dev. 312 */ 313 rc = l2tp_session_register(session, tunnel); 314 if (rc < 0) { 315 rtnl_unlock(); 316 goto err_sess_dev; 317 } 318 319 rc = register_netdevice(dev); 320 if (rc < 0) { 321 rtnl_unlock(); 322 l2tp_session_delete(session); 323 l2tp_session_dec_refcount(session); 324 free_netdev(dev); 325 326 return rc; 327 } 328 329 strlcpy(session->ifname, dev->name, IFNAMSIZ); 330 rcu_assign_pointer(spriv->dev, dev); 331 332 rtnl_unlock(); 333 334 l2tp_session_dec_refcount(session); 335 336 __module_get(THIS_MODULE); 337 338 return 0; 339 340 err_sess_dev: 341 l2tp_session_dec_refcount(session); 342 free_netdev(dev); 343 err_sess: 344 kfree(session); 345 err: 346 return rc; 347 } 348 349 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 350 .session_create = l2tp_eth_create, 351 .session_delete = l2tp_session_delete, 352 }; 353 354 static int __init l2tp_eth_init(void) 355 { 356 int err = 0; 357 358 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 359 if (err) 360 goto err; 361 362 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 363 364 return 0; 365 366 err: 367 return err; 368 } 369 370 static void __exit l2tp_eth_exit(void) 371 { 372 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 373 } 374 375 module_init(l2tp_eth_init); 376 module_exit(l2tp_eth_exit); 377 378 MODULE_LICENSE("GPL"); 379 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 380 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 381 MODULE_VERSION("1.0"); 382 MODULE_ALIAS_L2TP_PWTYPE(5); 383