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 }; 41 42 /* via l2tp_session_priv() */ 43 struct l2tp_eth_sess { 44 struct net_device __rcu *dev; 45 }; 46 47 static int l2tp_eth_dev_init(struct net_device *dev) 48 { 49 eth_hw_addr_random(dev); 50 eth_broadcast_addr(dev->broadcast); 51 netdev_lockdep_set_classes(dev); 52 53 return 0; 54 } 55 56 static void l2tp_eth_dev_uninit(struct net_device *dev) 57 { 58 struct l2tp_eth *priv = netdev_priv(dev); 59 struct l2tp_eth_sess *spriv; 60 61 spriv = l2tp_session_priv(priv->session); 62 RCU_INIT_POINTER(spriv->dev, NULL); 63 /* No need for synchronize_net() here. We're called by 64 * unregister_netdev*(), which does the synchronisation for us. 65 */ 66 } 67 68 static netdev_tx_t l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev) 69 { 70 struct l2tp_eth *priv = netdev_priv(dev); 71 struct l2tp_session *session = priv->session; 72 unsigned int len = skb->len; 73 int ret = l2tp_xmit_skb(session, skb); 74 75 if (likely(ret == NET_XMIT_SUCCESS)) 76 dev_dstats_tx_add(dev, len); 77 else 78 dev_dstats_tx_dropped(dev); 79 80 return NETDEV_TX_OK; 81 } 82 83 static const struct net_device_ops l2tp_eth_netdev_ops = { 84 .ndo_init = l2tp_eth_dev_init, 85 .ndo_uninit = l2tp_eth_dev_uninit, 86 .ndo_start_xmit = l2tp_eth_dev_xmit, 87 .ndo_set_mac_address = eth_mac_addr, 88 }; 89 90 static const struct device_type l2tpeth_type = { 91 .name = "l2tpeth", 92 }; 93 94 static void l2tp_eth_dev_setup(struct net_device *dev) 95 { 96 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 97 ether_setup(dev); 98 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 99 dev->lltx = true; 100 dev->netdev_ops = &l2tp_eth_netdev_ops; 101 dev->needs_free_netdev = true; 102 dev->pcpu_stat_type = NETDEV_PCPU_STAT_DSTATS; 103 } 104 105 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 106 { 107 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 108 struct net_device *dev; 109 110 if (!pskb_may_pull(skb, ETH_HLEN)) 111 goto error; 112 113 secpath_reset(skb); 114 115 /* checksums verified by L2TP */ 116 skb->ip_summed = CHECKSUM_NONE; 117 118 /* drop outer flow-hash */ 119 skb_clear_hash(skb); 120 121 skb_dst_drop(skb); 122 nf_reset_ct(skb); 123 124 rcu_read_lock(); 125 dev = rcu_dereference(spriv->dev); 126 if (!dev) 127 goto error_rcu; 128 129 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) 130 dev_dstats_rx_add(dev, data_len); 131 else 132 DEV_STATS_INC(dev, rx_errors); 133 134 rcu_read_unlock(); 135 136 return; 137 138 error_rcu: 139 rcu_read_unlock(); 140 error: 141 kfree_skb(skb); 142 } 143 144 static void l2tp_eth_delete(struct l2tp_session *session) 145 { 146 struct l2tp_eth_sess *spriv; 147 struct net_device *dev; 148 149 if (session) { 150 spriv = l2tp_session_priv(session); 151 152 rtnl_lock(); 153 dev = rtnl_dereference(spriv->dev); 154 if (dev) { 155 unregister_netdevice(dev); 156 rtnl_unlock(); 157 module_put(THIS_MODULE); 158 } else { 159 rtnl_unlock(); 160 } 161 } 162 } 163 164 static void l2tp_eth_show(struct seq_file *m, void *arg) 165 { 166 struct l2tp_session *session = arg; 167 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 168 struct net_device *dev; 169 170 rcu_read_lock(); 171 dev = rcu_dereference(spriv->dev); 172 if (!dev) { 173 rcu_read_unlock(); 174 return; 175 } 176 dev_hold(dev); 177 rcu_read_unlock(); 178 179 seq_printf(m, " interface %s\n", dev->name); 180 181 dev_put(dev); 182 } 183 184 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 185 struct l2tp_session *session, 186 struct net_device *dev) 187 { 188 unsigned int overhead = 0; 189 u32 l3_overhead = 0; 190 u32 mtu; 191 192 /* if the encap is UDP, account for UDP header size */ 193 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 194 overhead += sizeof(struct udphdr); 195 dev->needed_headroom += sizeof(struct udphdr); 196 } 197 198 lock_sock(tunnel->sock); 199 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 200 release_sock(tunnel->sock); 201 202 if (l3_overhead == 0) { 203 /* L3 Overhead couldn't be identified, this could be 204 * because tunnel->sock was NULL or the socket's 205 * address family was not IPv4 or IPv6, 206 * dev mtu stays at 1500. 207 */ 208 return; 209 } 210 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 211 * UDP overhead, if any, was already factored in above. 212 */ 213 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 214 215 mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead; 216 if (mtu < dev->min_mtu || mtu > dev->max_mtu) 217 dev->mtu = ETH_DATA_LEN - overhead; 218 else 219 dev->mtu = mtu; 220 221 dev->needed_headroom += session->hdr_len; 222 } 223 224 static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel, 225 u32 session_id, u32 peer_session_id, 226 struct l2tp_session_cfg *cfg) 227 { 228 unsigned char name_assign_type; 229 struct net_device *dev; 230 char name[IFNAMSIZ]; 231 struct l2tp_session *session; 232 struct l2tp_eth *priv; 233 struct l2tp_eth_sess *spriv; 234 int rc; 235 236 if (cfg->ifname) { 237 strscpy(name, cfg->ifname, IFNAMSIZ); 238 name_assign_type = NET_NAME_USER; 239 } else { 240 strcpy(name, L2TP_ETH_DEV_NAME); 241 name_assign_type = NET_NAME_ENUM; 242 } 243 244 session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, 245 peer_session_id, cfg); 246 if (IS_ERR(session)) { 247 rc = PTR_ERR(session); 248 goto err; 249 } 250 251 dev = alloc_netdev(sizeof(*priv), name, name_assign_type, 252 l2tp_eth_dev_setup); 253 if (!dev) { 254 rc = -ENOMEM; 255 goto err_sess; 256 } 257 258 dev_net_set(dev, net); 259 dev->min_mtu = 0; 260 dev->max_mtu = ETH_MAX_MTU; 261 l2tp_eth_adjust_mtu(tunnel, session, dev); 262 263 priv = netdev_priv(dev); 264 priv->session = session; 265 266 session->recv_skb = l2tp_eth_dev_recv; 267 session->session_close = l2tp_eth_delete; 268 if (IS_ENABLED(CONFIG_L2TP_DEBUGFS)) 269 session->show = l2tp_eth_show; 270 271 spriv = l2tp_session_priv(session); 272 273 refcount_inc(&session->ref_count); 274 275 rtnl_lock(); 276 277 /* Register both device and session while holding the rtnl lock. This 278 * ensures that l2tp_eth_delete() will see that there's a device to 279 * unregister, even if it happened to run before we assign spriv->dev. 280 */ 281 rc = l2tp_session_register(session, tunnel); 282 if (rc < 0) { 283 rtnl_unlock(); 284 goto err_sess_dev; 285 } 286 287 rc = register_netdevice(dev); 288 if (rc < 0) { 289 rtnl_unlock(); 290 l2tp_session_delete(session); 291 l2tp_session_put(session); 292 free_netdev(dev); 293 294 return rc; 295 } 296 297 strscpy(session->ifname, dev->name, IFNAMSIZ); 298 rcu_assign_pointer(spriv->dev, dev); 299 300 rtnl_unlock(); 301 302 l2tp_session_put(session); 303 304 __module_get(THIS_MODULE); 305 306 return 0; 307 308 err_sess_dev: 309 l2tp_session_put(session); 310 free_netdev(dev); 311 err_sess: 312 l2tp_session_put(session); 313 err: 314 return rc; 315 } 316 317 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 318 .session_create = l2tp_eth_create, 319 .session_delete = l2tp_session_delete, 320 }; 321 322 static int __init l2tp_eth_init(void) 323 { 324 int err = 0; 325 326 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 327 if (err) 328 goto err; 329 330 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 331 332 return 0; 333 334 err: 335 return err; 336 } 337 338 static void __exit l2tp_eth_exit(void) 339 { 340 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 341 } 342 343 module_init(l2tp_eth_init); 344 module_exit(l2tp_eth_exit); 345 346 MODULE_LICENSE("GPL"); 347 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 348 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 349 MODULE_VERSION("1.0"); 350 MODULE_ALIAS_L2TP_PWTYPE(5); 351