1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* L2TPv3 ethernet pseudowire driver 3 * 4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 5 */ 6 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/module.h> 10 #include <linux/skbuff.h> 11 #include <linux/socket.h> 12 #include <linux/hash.h> 13 #include <linux/l2tp.h> 14 #include <linux/in.h> 15 #include <linux/etherdevice.h> 16 #include <linux/spinlock.h> 17 #include <net/sock.h> 18 #include <net/ip.h> 19 #include <net/icmp.h> 20 #include <net/udp.h> 21 #include <net/inet_common.h> 22 #include <net/inet_hashtables.h> 23 #include <net/tcp_states.h> 24 #include <net/protocol.h> 25 #include <net/xfrm.h> 26 #include <net/net_namespace.h> 27 #include <net/netns/generic.h> 28 #include <linux/ip.h> 29 #include <linux/ipv6.h> 30 #include <linux/udp.h> 31 32 #include "l2tp_core.h" 33 34 /* Default device name. May be overridden by name specified by user */ 35 #define L2TP_ETH_DEV_NAME "l2tpeth%d" 36 37 /* via netdev_priv() */ 38 struct l2tp_eth { 39 struct l2tp_session *session; 40 atomic_long_t tx_bytes; 41 atomic_long_t tx_packets; 42 atomic_long_t tx_dropped; 43 atomic_long_t rx_bytes; 44 atomic_long_t rx_packets; 45 atomic_long_t rx_errors; 46 }; 47 48 /* via l2tp_session_priv() */ 49 struct l2tp_eth_sess { 50 struct net_device __rcu *dev; 51 }; 52 53 static int l2tp_eth_dev_init(struct net_device *dev) 54 { 55 eth_hw_addr_random(dev); 56 eth_broadcast_addr(dev->broadcast); 57 netdev_lockdep_set_classes(dev); 58 59 return 0; 60 } 61 62 static void l2tp_eth_dev_uninit(struct net_device *dev) 63 { 64 struct l2tp_eth *priv = netdev_priv(dev); 65 struct l2tp_eth_sess *spriv; 66 67 spriv = l2tp_session_priv(priv->session); 68 RCU_INIT_POINTER(spriv->dev, NULL); 69 /* No need for synchronize_net() here. We're called by 70 * unregister_netdev*(), which does the synchronisation for us. 71 */ 72 } 73 74 static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev) 75 { 76 struct l2tp_eth *priv = netdev_priv(dev); 77 struct l2tp_session *session = priv->session; 78 unsigned int len = skb->len; 79 int ret = l2tp_xmit_skb(session, skb, session->hdr_len); 80 81 if (likely(ret == NET_XMIT_SUCCESS)) { 82 atomic_long_add(len, &priv->tx_bytes); 83 atomic_long_inc(&priv->tx_packets); 84 } else { 85 atomic_long_inc(&priv->tx_dropped); 86 } 87 return NETDEV_TX_OK; 88 } 89 90 static void l2tp_eth_get_stats64(struct net_device *dev, 91 struct rtnl_link_stats64 *stats) 92 { 93 struct l2tp_eth *priv = netdev_priv(dev); 94 95 stats->tx_bytes = (unsigned long)atomic_long_read(&priv->tx_bytes); 96 stats->tx_packets = (unsigned long)atomic_long_read(&priv->tx_packets); 97 stats->tx_dropped = (unsigned long)atomic_long_read(&priv->tx_dropped); 98 stats->rx_bytes = (unsigned long)atomic_long_read(&priv->rx_bytes); 99 stats->rx_packets = (unsigned long)atomic_long_read(&priv->rx_packets); 100 stats->rx_errors = (unsigned long)atomic_long_read(&priv->rx_errors); 101 } 102 103 static const struct net_device_ops l2tp_eth_netdev_ops = { 104 .ndo_init = l2tp_eth_dev_init, 105 .ndo_uninit = l2tp_eth_dev_uninit, 106 .ndo_start_xmit = l2tp_eth_dev_xmit, 107 .ndo_get_stats64 = l2tp_eth_get_stats64, 108 .ndo_set_mac_address = eth_mac_addr, 109 }; 110 111 static struct device_type l2tpeth_type = { 112 .name = "l2tpeth", 113 }; 114 115 static void l2tp_eth_dev_setup(struct net_device *dev) 116 { 117 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 118 ether_setup(dev); 119 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 120 dev->features |= NETIF_F_LLTX; 121 dev->netdev_ops = &l2tp_eth_netdev_ops; 122 dev->needs_free_netdev = true; 123 } 124 125 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 126 { 127 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 128 struct net_device *dev; 129 struct l2tp_eth *priv; 130 131 if (session->debug & L2TP_MSG_DATA) { 132 unsigned int length; 133 134 length = min(32u, skb->len); 135 if (!pskb_may_pull(skb, length)) 136 goto error; 137 138 pr_debug("%s: eth recv\n", session->name); 139 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 140 } 141 142 if (!pskb_may_pull(skb, ETH_HLEN)) 143 goto error; 144 145 secpath_reset(skb); 146 147 /* checksums verified by L2TP */ 148 skb->ip_summed = CHECKSUM_NONE; 149 150 skb_dst_drop(skb); 151 nf_reset_ct(skb); 152 153 rcu_read_lock(); 154 dev = rcu_dereference(spriv->dev); 155 if (!dev) 156 goto error_rcu; 157 158 priv = netdev_priv(dev); 159 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 160 atomic_long_inc(&priv->rx_packets); 161 atomic_long_add(data_len, &priv->rx_bytes); 162 } else { 163 atomic_long_inc(&priv->rx_errors); 164 } 165 rcu_read_unlock(); 166 167 return; 168 169 error_rcu: 170 rcu_read_unlock(); 171 error: 172 kfree_skb(skb); 173 } 174 175 static void l2tp_eth_delete(struct l2tp_session *session) 176 { 177 struct l2tp_eth_sess *spriv; 178 struct net_device *dev; 179 180 if (session) { 181 spriv = l2tp_session_priv(session); 182 183 rtnl_lock(); 184 dev = rtnl_dereference(spriv->dev); 185 if (dev) { 186 unregister_netdevice(dev); 187 rtnl_unlock(); 188 module_put(THIS_MODULE); 189 } else { 190 rtnl_unlock(); 191 } 192 } 193 } 194 195 static void l2tp_eth_show(struct seq_file *m, void *arg) 196 { 197 struct l2tp_session *session = arg; 198 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 199 struct net_device *dev; 200 201 rcu_read_lock(); 202 dev = rcu_dereference(spriv->dev); 203 if (!dev) { 204 rcu_read_unlock(); 205 return; 206 } 207 dev_hold(dev); 208 rcu_read_unlock(); 209 210 seq_printf(m, " interface %s\n", dev->name); 211 212 dev_put(dev); 213 } 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 u32 l3_overhead = 0; 221 u32 mtu; 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 } 228 229 lock_sock(tunnel->sock); 230 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 231 release_sock(tunnel->sock); 232 233 if (l3_overhead == 0) { 234 /* L3 Overhead couldn't be identified, this could be 235 * because tunnel->sock was NULL or the socket's 236 * address family was not IPv4 or IPv6, 237 * dev mtu stays at 1500. 238 */ 239 return; 240 } 241 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 242 * UDP overhead, if any, was already factored in above. 243 */ 244 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 245 246 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 247 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 248 dev->mtu = ETH_DATA_LEN - overhead; 249 else 250 dev->mtu = mtu; 251 252 dev->needed_headroom += session->hdr_len; 253 } 254 255 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 256 u32 session_id, u32 peer_session_id, 257 struct l2tp_session_cfg *cfg) 258 { 259 unsigned char name_assign_type; 260 struct net_device *dev; 261 char name[IFNAMSIZ]; 262 struct l2tp_session *session; 263 struct l2tp_eth *priv; 264 struct l2tp_eth_sess *spriv; 265 int rc; 266 267 if (cfg->ifname) { 268 strlcpy(name, cfg->ifname, IFNAMSIZ); 269 name_assign_type = NET_NAME_USER; 270 } else { 271 strcpy(name, L2TP_ETH_DEV_NAME); 272 name_assign_type = NET_NAME_ENUM; 273 } 274 275 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 276 peer_session_id, cfg); 277 if (IS_ERR(session)) { 278 rc = PTR_ERR(session); 279 goto err; 280 } 281 282 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 283 l2tp_eth_dev_setup); 284 if (!dev) { 285 rc = -ENOMEM; 286 goto err_sess; 287 } 288 289 dev_net_set(dev, net); 290 dev->min_mtu = 0; 291 dev->max_mtu = ETH_MAX_MTU; 292 l2tp_eth_adjust_mtu(tunnel, session, dev); 293 294 priv = netdev_priv(dev); 295 priv->session = session; 296 297 session->recv_skb = l2tp_eth_dev_recv; 298 session->session_close = l2tp_eth_delete; 299 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 300 session->show = l2tp_eth_show; 301 302 spriv = l2tp_session_priv(session); 303 304 l2tp_session_inc_refcount(session); 305 306 rtnl_lock(); 307 308 /* Register both device and session while holding the rtnl lock. This 309 * ensures that l2tp_eth_delete() will see that there's a device to 310 * unregister, even if it happened to run before we assign spriv->dev. 311 */ 312 rc = l2tp_session_register(session, tunnel); 313 if (rc < 0) { 314 rtnl_unlock(); 315 goto err_sess_dev; 316 } 317 318 rc = register_netdevice(dev); 319 if (rc < 0) { 320 rtnl_unlock(); 321 l2tp_session_delete(session); 322 l2tp_session_dec_refcount(session); 323 free_netdev(dev); 324 325 return rc; 326 } 327 328 strlcpy(session->ifname, dev->name, IFNAMSIZ); 329 rcu_assign_pointer(spriv->dev, dev); 330 331 rtnl_unlock(); 332 333 l2tp_session_dec_refcount(session); 334 335 __module_get(THIS_MODULE); 336 337 return 0; 338 339 err_sess_dev: 340 l2tp_session_dec_refcount(session); 341 free_netdev(dev); 342 err_sess: 343 kfree(session); 344 err: 345 return rc; 346 } 347 348 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 349 .session_create = l2tp_eth_create, 350 .session_delete = l2tp_session_delete, 351 }; 352 353 static int __init l2tp_eth_init(void) 354 { 355 int err = 0; 356 357 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 358 if (err) 359 goto err; 360 361 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 362 363 return 0; 364 365 err: 366 return err; 367 } 368 369 static void __exit l2tp_eth_exit(void) 370 { 371 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 372 } 373 374 module_init(l2tp_eth_init); 375 module_exit(l2tp_eth_exit); 376 377 MODULE_LICENSE("GPL"); 378 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 379 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 380 MODULE_VERSION("1.0"); 381 MODULE_ALIAS_L2TP_PWTYPE(5); 382