1 /* 2 * L2TPv3 ethernet pseudowire driver 3 * 4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 13 14 #include <linux/module.h> 15 #include <linux/skbuff.h> 16 #include <linux/socket.h> 17 #include <linux/hash.h> 18 #include <linux/l2tp.h> 19 #include <linux/in.h> 20 #include <linux/etherdevice.h> 21 #include <linux/spinlock.h> 22 #include <net/sock.h> 23 #include <net/ip.h> 24 #include <net/icmp.h> 25 #include <net/udp.h> 26 #include <net/inet_common.h> 27 #include <net/inet_hashtables.h> 28 #include <net/tcp_states.h> 29 #include <net/protocol.h> 30 #include <net/xfrm.h> 31 #include <net/net_namespace.h> 32 #include <net/netns/generic.h> 33 #include <linux/ip.h> 34 #include <linux/ipv6.h> 35 #include <linux/udp.h> 36 37 #include "l2tp_core.h" 38 39 /* Default device name. May be overridden by name specified by user */ 40 #define L2TP_ETH_DEV_NAME "l2tpeth%d" 41 42 /* via netdev_priv() */ 43 struct l2tp_eth { 44 struct net_device *dev; 45 struct sock *tunnel_sock; 46 struct l2tp_session *session; 47 atomic_long_t tx_bytes; 48 atomic_long_t tx_packets; 49 atomic_long_t tx_dropped; 50 atomic_long_t rx_bytes; 51 atomic_long_t rx_packets; 52 atomic_long_t rx_errors; 53 }; 54 55 /* via l2tp_session_priv() */ 56 struct l2tp_eth_sess { 57 struct net_device *dev; 58 }; 59 60 61 static int l2tp_eth_dev_init(struct net_device *dev) 62 { 63 struct l2tp_eth *priv = netdev_priv(dev); 64 65 priv->dev = dev; 66 eth_hw_addr_random(dev); 67 eth_broadcast_addr(dev->broadcast); 68 netdev_lockdep_set_classes(dev); 69 70 return 0; 71 } 72 73 static void l2tp_eth_dev_uninit(struct net_device *dev) 74 { 75 dev_put(dev); 76 } 77 78 static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev) 79 { 80 struct l2tp_eth *priv = netdev_priv(dev); 81 struct l2tp_session *session = priv->session; 82 unsigned int len = skb->len; 83 int ret = l2tp_xmit_skb(session, skb, session->hdr_len); 84 85 if (likely(ret == NET_XMIT_SUCCESS)) { 86 atomic_long_add(len, &priv->tx_bytes); 87 atomic_long_inc(&priv->tx_packets); 88 } else { 89 atomic_long_inc(&priv->tx_dropped); 90 } 91 return NETDEV_TX_OK; 92 } 93 94 static void l2tp_eth_get_stats64(struct net_device *dev, 95 struct rtnl_link_stats64 *stats) 96 { 97 struct l2tp_eth *priv = netdev_priv(dev); 98 99 stats->tx_bytes = (unsigned long) atomic_long_read(&priv->tx_bytes); 100 stats->tx_packets = (unsigned long) atomic_long_read(&priv->tx_packets); 101 stats->tx_dropped = (unsigned long) atomic_long_read(&priv->tx_dropped); 102 stats->rx_bytes = (unsigned long) atomic_long_read(&priv->rx_bytes); 103 stats->rx_packets = (unsigned long) atomic_long_read(&priv->rx_packets); 104 stats->rx_errors = (unsigned long) atomic_long_read(&priv->rx_errors); 105 106 } 107 108 static const struct net_device_ops l2tp_eth_netdev_ops = { 109 .ndo_init = l2tp_eth_dev_init, 110 .ndo_uninit = l2tp_eth_dev_uninit, 111 .ndo_start_xmit = l2tp_eth_dev_xmit, 112 .ndo_get_stats64 = l2tp_eth_get_stats64, 113 .ndo_set_mac_address = eth_mac_addr, 114 }; 115 116 static struct device_type l2tpeth_type = { 117 .name = "l2tpeth", 118 }; 119 120 static void l2tp_eth_dev_setup(struct net_device *dev) 121 { 122 SET_NETDEV_DEVTYPE(dev, &l2tpeth_type); 123 ether_setup(dev); 124 dev->priv_flags &= ~IFF_TX_SKB_SHARING; 125 dev->features |= NETIF_F_LLTX; 126 dev->netdev_ops = &l2tp_eth_netdev_ops; 127 dev->needs_free_netdev = true; 128 } 129 130 static void l2tp_eth_dev_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) 131 { 132 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 133 struct net_device *dev = spriv->dev; 134 struct l2tp_eth *priv = netdev_priv(dev); 135 136 if (session->debug & L2TP_MSG_DATA) { 137 unsigned int length; 138 139 length = min(32u, skb->len); 140 if (!pskb_may_pull(skb, length)) 141 goto error; 142 143 pr_debug("%s: eth recv\n", session->name); 144 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 145 } 146 147 if (!pskb_may_pull(skb, ETH_HLEN)) 148 goto error; 149 150 secpath_reset(skb); 151 152 /* checksums verified by L2TP */ 153 skb->ip_summed = CHECKSUM_NONE; 154 155 skb_dst_drop(skb); 156 nf_reset(skb); 157 158 if (dev_forward_skb(dev, skb) == NET_RX_SUCCESS) { 159 atomic_long_inc(&priv->rx_packets); 160 atomic_long_add(data_len, &priv->rx_bytes); 161 } else { 162 atomic_long_inc(&priv->rx_errors); 163 } 164 return; 165 166 error: 167 atomic_long_inc(&priv->rx_errors); 168 kfree_skb(skb); 169 } 170 171 static void l2tp_eth_delete(struct l2tp_session *session) 172 { 173 struct l2tp_eth_sess *spriv; 174 struct net_device *dev; 175 176 if (session) { 177 spriv = l2tp_session_priv(session); 178 dev = spriv->dev; 179 if (dev) { 180 unregister_netdev(dev); 181 spriv->dev = NULL; 182 module_put(THIS_MODULE); 183 } 184 } 185 } 186 187 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS) 188 static void l2tp_eth_show(struct seq_file *m, void *arg) 189 { 190 struct l2tp_session *session = arg; 191 struct l2tp_eth_sess *spriv = l2tp_session_priv(session); 192 struct net_device *dev = spriv->dev; 193 194 seq_printf(m, " interface %s\n", dev->name); 195 } 196 #endif 197 198 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 199 struct l2tp_session *session, 200 struct net_device *dev) 201 { 202 unsigned int overhead = 0; 203 struct dst_entry *dst; 204 u32 l3_overhead = 0; 205 206 /* if the encap is UDP, account for UDP header size */ 207 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 208 overhead += sizeof(struct udphdr); 209 dev->needed_headroom += sizeof(struct udphdr); 210 } 211 if (session->mtu != 0) { 212 dev->mtu = session->mtu; 213 dev->needed_headroom += session->hdr_len; 214 return; 215 } 216 lock_sock(tunnel->sock); 217 l3_overhead = kernel_sock_ip_overhead(tunnel->sock); 218 release_sock(tunnel->sock); 219 if (l3_overhead == 0) { 220 /* L3 Overhead couldn't be identified, this could be 221 * because tunnel->sock was NULL or the socket's 222 * address family was not IPv4 or IPv6, 223 * dev mtu stays at 1500. 224 */ 225 return; 226 } 227 /* Adjust MTU, factor overhead - underlay L3, overlay L2 hdr 228 * UDP overhead, if any, was already factored in above. 229 */ 230 overhead += session->hdr_len + ETH_HLEN + l3_overhead; 231 232 /* If PMTU discovery was enabled, use discovered MTU on L2TP device */ 233 dst = sk_dst_get(tunnel->sock); 234 if (dst) { 235 /* dst_mtu will use PMTU if found, else fallback to intf MTU */ 236 u32 pmtu = dst_mtu(dst); 237 238 if (pmtu != 0) 239 dev->mtu = pmtu; 240 dst_release(dst); 241 } 242 session->mtu = dev->mtu - overhead; 243 dev->mtu = session->mtu; 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 strlcpy(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 out; 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 out_del_session; 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->dev = dev; 288 priv->session = session; 289 290 priv->tunnel_sock = tunnel->sock; 291 session->recv_skb = l2tp_eth_dev_recv; 292 session->session_close = l2tp_eth_delete; 293 #if IS_ENABLED(CONFIG_L2TP_DEBUGFS) 294 session->show = l2tp_eth_show; 295 #endif 296 297 spriv = l2tp_session_priv(session); 298 spriv->dev = dev; 299 300 rc = register_netdev(dev); 301 if (rc < 0) 302 goto out_del_dev; 303 304 __module_get(THIS_MODULE); 305 /* Must be done after register_netdev() */ 306 strlcpy(session->ifname, dev->name, IFNAMSIZ); 307 308 dev_hold(dev); 309 310 return 0; 311 312 out_del_dev: 313 free_netdev(dev); 314 spriv->dev = NULL; 315 out_del_session: 316 l2tp_session_delete(session); 317 out: 318 return rc; 319 } 320 321 322 static const struct l2tp_nl_cmd_ops l2tp_eth_nl_cmd_ops = { 323 .session_create = l2tp_eth_create, 324 .session_delete = l2tp_session_delete, 325 }; 326 327 328 static int __init l2tp_eth_init(void) 329 { 330 int err = 0; 331 332 err = l2tp_nl_register_ops(L2TP_PWTYPE_ETH, &l2tp_eth_nl_cmd_ops); 333 if (err) 334 goto err; 335 336 pr_info("L2TP ethernet pseudowire support (L2TPv3)\n"); 337 338 return 0; 339 340 err: 341 return err; 342 } 343 344 static void __exit l2tp_eth_exit(void) 345 { 346 l2tp_nl_unregister_ops(L2TP_PWTYPE_ETH); 347 } 348 349 module_init(l2tp_eth_init); 350 module_exit(l2tp_eth_exit); 351 352 MODULE_LICENSE("GPL"); 353 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 354 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver"); 355 MODULE_VERSION("1.0"); 356 MODULE_ALIAS_L2TP_PWTYPE(5); 357