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