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); 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 (!pskb_may_pull(skb, ETH_HLEN)) 132 goto error; 133 134 secpath_reset(skb); 135 136 /* checksums verified by L2TP */ 137 skb->ip_summed = CHECKSUM_NONE; 138 139 /* drop outer flow-hash */ 140 skb_clear_hash(skb); 141 142 skb_dst_drop(skb); 143 nf_reset_ct(skb); 144 145 rcu_read_lock(); 146 dev = rcu_dereference(spriv->dev); 147 if (!dev) 148 goto error_rcu; 149 150 priv = netdev_priv(dev); 151 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 152 atomic_long_inc(&priv->rx_packets); 153 atomic_long_add(data_len, &priv->rx_bytes); 154 } else { 155 atomic_long_inc(&priv->rx_errors); 156 } 157 rcu_read_unlock(); 158 159 return; 160 161 error_rcu: 162 rcu_read_unlock(); 163 error: 164 kfree_skb(skb); 165 } 166 167 static void l2tp_eth_delete(struct l2tp_session *session) 168 { 169 struct l2tp_eth_sess *spriv; 170 struct net_device *dev; 171 172 if (session) { 173 spriv = l2tp_session_priv(session); 174 175 rtnl_lock(); 176 dev = rtnl_dereference(spriv->dev); 177 if (dev) { 178 unregister_netdevice(dev); 179 rtnl_unlock(); 180 module_put(THIS_MODULE); 181 } else { 182 rtnl_unlock(); 183 } 184 } 185 } 186 187 static void l2tp_eth_show(struct seq_file *m, void *arg) 188 { 189 struct l2tp_session *session = arg; 190 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 191 struct net_device *dev; 192 193 rcu_read_lock(); 194 dev = rcu_dereference(spriv->dev); 195 if (!dev) { 196 rcu_read_unlock(); 197 return; 198 } 199 dev_hold(dev); 200 rcu_read_unlock(); 201 202 seq_printf(m, " interface %s\n", dev->name); 203 204 dev_put(dev); 205 } 206 207 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 208 struct l2tp_session *session, 209 struct net_device *dev) 210 { 211 unsigned int overhead = 0; 212 u32 l3_overhead = 0; 213 u32 mtu; 214 215 /* if the encap is UDP, account for UDP header size */ 216 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 217 overhead += sizeof(struct udphdr); 218 dev->needed_headroom += sizeof(struct udphdr); 219 } 220 221 lock_sock(tunnel->sock); 222 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 223 release_sock(tunnel->sock); 224 225 if (l3_overhead == 0) { 226 /* L3 Overhead couldn't be identified, this could be 227 * because tunnel->sock was NULL or the socket's 228 * address family was not IPv4 or IPv6, 229 * dev mtu stays at 1500. 230 */ 231 return; 232 } 233 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 234 * UDP overhead, if any, was already factored in above. 235 */ 236 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 237 238 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 239 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 240 dev->mtu = ETH_DATA_LEN - overhead; 241 else 242 dev->mtu = mtu; 243 244 dev->needed_headroom += session->hdr_len; 245 } 246 247 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 248 u32 session_id, u32 peer_session_id, 249 struct l2tp_session_cfg *cfg) 250 { 251 unsigned char name_assign_type; 252 struct net_device *dev; 253 char name[IFNAMSIZ]; 254 struct l2tp_session *session; 255 struct l2tp_eth *priv; 256 struct l2tp_eth_sess *spriv; 257 int rc; 258 259 if (cfg->ifname) { 260 strscpy(name, cfg->ifname, IFNAMSIZ); 261 name_assign_type = NET_NAME_USER; 262 } else { 263 strcpy(name, L2TP_ETH_DEV_NAME); 264 name_assign_type = NET_NAME_ENUM; 265 } 266 267 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 268 peer_session_id, cfg); 269 if (IS_ERR(session)) { 270 rc = PTR_ERR(session); 271 goto err; 272 } 273 274 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 275 l2tp_eth_dev_setup); 276 if (!dev) { 277 rc = -ENOMEM; 278 goto err_sess; 279 } 280 281 dev_net_set(dev, net); 282 dev->min_mtu = 0; 283 dev->max_mtu = ETH_MAX_MTU; 284 l2tp_eth_adjust_mtu(tunnel, session, dev); 285 286 priv = netdev_priv(dev); 287 priv->session = session; 288 289 session->recv_skb = l2tp_eth_dev_recv; 290 session->session_close = l2tp_eth_delete; 291 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 292 session->show = l2tp_eth_show; 293 294 spriv = l2tp_session_priv(session); 295 296 l2tp_session_inc_refcount(session); 297 298 rtnl_lock(); 299 300 /* Register both device and session while holding the rtnl lock. This 301 * ensures that l2tp_eth_delete() will see that there's a device to 302 * unregister, even if it happened to run before we assign spriv->dev. 303 */ 304 rc = l2tp_session_register(session, tunnel); 305 if (rc < 0) { 306 rtnl_unlock(); 307 goto err_sess_dev; 308 } 309 310 rc = register_netdevice(dev); 311 if (rc < 0) { 312 rtnl_unlock(); 313 l2tp_session_delete(session); 314 l2tp_session_dec_refcount(session); 315 free_netdev(dev); 316 317 return rc; 318 } 319 320 strscpy(session->ifname, dev->name, IFNAMSIZ); 321 rcu_assign_pointer(spriv->dev, dev); 322 323 rtnl_unlock(); 324 325 l2tp_session_dec_refcount(session); 326 327 __module_get(THIS_MODULE); 328 329 return 0; 330 331 err_sess_dev: 332 l2tp_session_dec_refcount(session); 333 free_netdev(dev); 334 err_sess: 335 kfree(session); 336 err: 337 return rc; 338 } 339 340 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 341 .session_create = l2tp_eth_create, 342 .session_delete = l2tp_session_delete, 343 }; 344 345 static int __init l2tp_eth_init(void) 346 { 347 int err = 0; 348 349 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 350 if (err) 351 goto err; 352 353 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 354 355 return 0; 356 357 err: 358 return err; 359 } 360 361 static void __exit l2tp_eth_exit(void) 362 { 363 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 364 } 365 366 module_init(l2tp_eth_init); 367 module_exit(l2tp_eth_exit); 368 369 MODULE_LICENSE("GPL"); 370 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 371 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 372 MODULE_VERSION("1.0"); 373 MODULE_ALIAS_L2TP_PWTYPE(5); 374