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 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 int 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 } 104 105 static const struct net_device_ops l2tp_eth_netdev_ops = { 106 .ndo_init = l2tp_eth_dev_init, 107 .ndo_uninit = l2tp_eth_dev_uninit, 108 .ndo_start_xmit = l2tp_eth_dev_xmit, 109 .ndo_get_stats64 = l2tp_eth_get_stats64, 110 .ndo_set_mac_address = eth_mac_addr, 111 }; 112 113 static struct device_type l2tpeth_type = { 114 .name = "l2tpeth", 115 }; 116 117 static void l2tp_eth_dev_setup(struct net_device *dev) 118 { 119 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 120 ether_setup(dev); 121 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 122 dev->features |= NETIF_F_LLTX; 123 dev->netdev_ops = &l2tp_eth_netdev_ops; 124 dev->needs_free_netdev = true; 125 } 126 127 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 128 { 129 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 130 struct net_device *dev; 131 struct l2tp_eth *priv; 132 133 if (session->debug & L2TP_MSG_DATA) { 134 unsigned int length; 135 136 length = min(32u, skb->len); 137 if (!pskb_may_pull(skb, length)) 138 goto error; 139 140 pr_debug("%s: eth recv\n", session->name); 141 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 142 } 143 144 if (!pskb_may_pull(skb, ETH_HLEN)) 145 goto error; 146 147 secpath_reset(skb); 148 149 /* checksums verified by L2TP */ 150 skb->ip_summed = CHECKSUM_NONE; 151 152 skb_dst_drop(skb); 153 nf_reset_ct(skb); 154 155 rcu_read_lock(); 156 dev = rcu_dereference(spriv->dev); 157 if (!dev) 158 goto error_rcu; 159 160 priv = netdev_priv(dev); 161 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 162 atomic_long_inc(&priv->rx_packets); 163 atomic_long_add(data_len, &priv->rx_bytes); 164 } else { 165 atomic_long_inc(&priv->rx_errors); 166 } 167 rcu_read_unlock(); 168 169 return; 170 171 error_rcu: 172 rcu_read_unlock(); 173 error: 174 kfree_skb(skb); 175 } 176 177 static void l2tp_eth_delete(struct l2tp_session *session) 178 { 179 struct l2tp_eth_sess *spriv; 180 struct net_device *dev; 181 182 if (session) { 183 spriv = l2tp_session_priv(session); 184 185 rtnl_lock(); 186 dev = rtnl_dereference(spriv->dev); 187 if (dev) { 188 unregister_netdevice(dev); 189 rtnl_unlock(); 190 module_put(THIS_MODULE); 191 } else { 192 rtnl_unlock(); 193 } 194 } 195 } 196 197 static void l2tp_eth_show(struct seq_file *m, void *arg) 198 { 199 struct l2tp_session *session = arg; 200 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 201 struct net_device *dev; 202 203 rcu_read_lock(); 204 dev = rcu_dereference(spriv->dev); 205 if (!dev) { 206 rcu_read_unlock(); 207 return; 208 } 209 dev_hold(dev); 210 rcu_read_unlock(); 211 212 seq_printf(m, " interface %s\n", dev->name); 213 214 dev_put(dev); 215 } 216 217 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 218 struct l2tp_session *session, 219 struct net_device *dev) 220 { 221 unsigned int overhead = 0; 222 u32 l3_overhead = 0; 223 u32 mtu; 224 225 /* if the encap is UDP, account for UDP header size */ 226 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 227 overhead += sizeof(struct udphdr); 228 dev->needed_headroom += sizeof(struct udphdr); 229 } 230 231 lock_sock(tunnel->sock); 232 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 233 release_sock(tunnel->sock); 234 235 if (l3_overhead == 0) { 236 /* L3 Overhead couldn't be identified, this could be 237 * because tunnel->sock was NULL or the socket's 238 * address family was not IPv4 or IPv6, 239 * dev mtu stays at 1500. 240 */ 241 return; 242 } 243 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 244 * UDP overhead, if any, was already factored in above. 245 */ 246 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 247 248 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 249 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 250 dev->mtu = ETH_DATA_LEN - overhead; 251 else 252 dev->mtu = mtu; 253 254 dev->needed_headroom += session->hdr_len; 255 } 256 257 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 258 u32 session_id, u32 peer_session_id, 259 struct l2tp_session_cfg *cfg) 260 { 261 unsigned char name_assign_type; 262 struct net_device *dev; 263 char name[IFNAMSIZ]; 264 struct l2tp_session *session; 265 struct l2tp_eth *priv; 266 struct l2tp_eth_sess *spriv; 267 int rc; 268 269 if (cfg->ifname) { 270 strlcpy(name, cfg->ifname, IFNAMSIZ); 271 name_assign_type = NET_NAME_USER; 272 } else { 273 strcpy(name, L2TP_ETH_DEV_NAME); 274 name_assign_type = NET_NAME_ENUM; 275 } 276 277 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 278 peer_session_id, cfg); 279 if (IS_ERR(session)) { 280 rc = PTR_ERR(session); 281 goto err; 282 } 283 284 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 285 l2tp_eth_dev_setup); 286 if (!dev) { 287 rc = -ENOMEM; 288 goto err_sess; 289 } 290 291 dev_net_set(dev, net); 292 dev->min_mtu = 0; 293 dev->max_mtu = ETH_MAX_MTU; 294 l2tp_eth_adjust_mtu(tunnel, session, dev); 295 296 priv = netdev_priv(dev); 297 priv->session = session; 298 299 session->recv_skb = l2tp_eth_dev_recv; 300 session->session_close = l2tp_eth_delete; 301 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 302 session->show = l2tp_eth_show; 303 304 spriv = l2tp_session_priv(session); 305 306 l2tp_session_inc_refcount(session); 307 308 rtnl_lock(); 309 310 /* Register both device and session while holding the rtnl lock. This 311 * ensures that l2tp_eth_delete() will see that there's a device to 312 * unregister, even if it happened to run before we assign spriv->dev. 313 */ 314 rc = l2tp_session_register(session, tunnel); 315 if (rc < 0) { 316 rtnl_unlock(); 317 goto err_sess_dev; 318 } 319 320 rc = register_netdevice(dev); 321 if (rc < 0) { 322 rtnl_unlock(); 323 l2tp_session_delete(session); 324 l2tp_session_dec_refcount(session); 325 free_netdev(dev); 326 327 return rc; 328 } 329 330 strlcpy(session->ifname, dev->name, IFNAMSIZ); 331 rcu_assign_pointer(spriv->dev, dev); 332 333 rtnl_unlock(); 334 335 l2tp_session_dec_refcount(session); 336 337 __module_get(THIS_MODULE); 338 339 return 0; 340 341 err_sess_dev: 342 l2tp_session_dec_refcount(session); 343 free_netdev(dev); 344 err_sess: 345 kfree(session); 346 err: 347 return rc; 348 } 349 350 351 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 352 .session_create = l2tp_eth_create, 353 .session_delete = l2tp_session_delete, 354 }; 355 356 357 static int __init l2tp_eth_init(void) 358 { 359 int err = 0; 360 361 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 362 if (err) 363 goto err; 364 365 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 366 367 return 0; 368 369 err: 370 return err; 371 } 372 373 static void __exit l2tp_eth_exit(void) 374 { 375 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 376 } 377 378 module_init(l2tp_eth_init); 379 module_exit(l2tp_eth_exit); 380 381 MODULE_LICENSE("GPL"); 382 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 383 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 384 MODULE_VERSION("1.0"); 385 MODULE_ALIAS_L2TP_PWTYPE(5); 386