1 /* 2 * "LAPB via ethernet" driver release 001 3 * 4 * This code REQUIRES 2.1.15 or higher/ NET3.038 5 * 6 * This module: 7 * This module is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * This is a "pseudo" network driver to allow LAPB over Ethernet. 13 * 14 * This driver can use any ethernet destination address, and can be 15 * limited to accept frames from one dedicated ethernet card only. 16 * 17 * History 18 * LAPBETH 001 Jonathan Naylor Cloned from bpqether.c 19 * 2000-10-29 Henner Eisen lapb_data_indication() return status. 20 * 2000-11-14 Henner Eisen dev_hold/put, NETDEV_GOING_DOWN support 21 */ 22 23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 24 25 #include <linux/errno.h> 26 #include <linux/types.h> 27 #include <linux/socket.h> 28 #include <linux/in.h> 29 #include <linux/slab.h> 30 #include <linux/kernel.h> 31 #include <linux/string.h> 32 #include <linux/net.h> 33 #include <linux/inet.h> 34 #include <linux/netdevice.h> 35 #include <linux/if_arp.h> 36 #include <linux/skbuff.h> 37 #include <net/sock.h> 38 #include <linux/uaccess.h> 39 #include <linux/mm.h> 40 #include <linux/interrupt.h> 41 #include <linux/notifier.h> 42 #include <linux/stat.h> 43 #include <linux/module.h> 44 #include <linux/lapb.h> 45 #include <linux/init.h> 46 47 #include <net/x25device.h> 48 49 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }; 50 51 /* If this number is made larger, check that the temporary string buffer 52 * in lapbeth_new_device is large enough to store the probe device name.*/ 53 #define MAXLAPBDEV 100 54 55 struct lapbethdev { 56 struct list_head node; 57 struct net_device *ethdev; /* link to ethernet device */ 58 struct net_device *axdev; /* lapbeth device (lapb#) */ 59 }; 60 61 static LIST_HEAD(lapbeth_devices); 62 63 /* ------------------------------------------------------------------------ */ 64 65 /* 66 * Get the LAPB device for the ethernet device 67 */ 68 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev) 69 { 70 struct lapbethdev *lapbeth; 71 72 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node) { 73 if (lapbeth->ethdev == dev) 74 return lapbeth; 75 } 76 return NULL; 77 } 78 79 static __inline__ int dev_is_ethdev(struct net_device *dev) 80 { 81 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 82 } 83 84 /* ------------------------------------------------------------------------ */ 85 86 /* 87 * Receive a LAPB frame via an ethernet interface. 88 */ 89 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 90 { 91 int len, err; 92 struct lapbethdev *lapbeth; 93 94 if (dev_net(dev) != &init_net) 95 goto drop; 96 97 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 98 return NET_RX_DROP; 99 100 if (!pskb_may_pull(skb, 2)) 101 goto drop; 102 103 rcu_read_lock(); 104 lapbeth = lapbeth_get_x25_dev(dev); 105 if (!lapbeth) 106 goto drop_unlock; 107 if (!netif_running(lapbeth->axdev)) 108 goto drop_unlock; 109 110 len = skb->data[0] + skb->data[1] * 256; 111 dev->stats.rx_packets++; 112 dev->stats.rx_bytes += len; 113 114 skb_pull(skb, 2); /* Remove the length bytes */ 115 skb_trim(skb, len); /* Set the length of the data */ 116 117 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) { 118 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err); 119 goto drop_unlock; 120 } 121 out: 122 rcu_read_unlock(); 123 return 0; 124 drop_unlock: 125 kfree_skb(skb); 126 goto out; 127 drop: 128 kfree_skb(skb); 129 return 0; 130 } 131 132 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) 133 { 134 unsigned char *ptr; 135 136 skb_push(skb, 1); 137 138 if (skb_cow(skb, 1)) 139 return NET_RX_DROP; 140 141 ptr = skb->data; 142 *ptr = X25_IFACE_DATA; 143 144 skb->protocol = x25_type_trans(skb, dev); 145 return netif_rx(skb); 146 } 147 148 /* 149 * Send a LAPB frame via an ethernet interface 150 */ 151 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, 152 struct net_device *dev) 153 { 154 int err; 155 156 /* 157 * Just to be *really* sure not to send anything if the interface 158 * is down, the ethernet device may have gone. 159 */ 160 if (!netif_running(dev)) 161 goto drop; 162 163 switch (skb->data[0]) { 164 case X25_IFACE_DATA: 165 break; 166 case X25_IFACE_CONNECT: 167 if ((err = lapb_connect_request(dev)) != LAPB_OK) 168 pr_err("lapb_connect_request error: %d\n", err); 169 goto drop; 170 case X25_IFACE_DISCONNECT: 171 if ((err = lapb_disconnect_request(dev)) != LAPB_OK) 172 pr_err("lapb_disconnect_request err: %d\n", err); 173 /* Fall thru */ 174 default: 175 goto drop; 176 } 177 178 skb_pull(skb, 1); 179 180 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) { 181 pr_err("lapb_data_request error - %d\n", err); 182 goto drop; 183 } 184 out: 185 return NETDEV_TX_OK; 186 drop: 187 kfree_skb(skb); 188 goto out; 189 } 190 191 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 192 { 193 struct lapbethdev *lapbeth = netdev_priv(ndev); 194 unsigned char *ptr; 195 struct net_device *dev; 196 int size = skb->len; 197 198 skb->protocol = htons(ETH_P_X25); 199 200 ptr = skb_push(skb, 2); 201 202 *ptr++ = size % 256; 203 *ptr++ = size / 256; 204 205 ndev->stats.tx_packets++; 206 ndev->stats.tx_bytes += size; 207 208 skb->dev = dev = lapbeth->ethdev; 209 210 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 211 212 dev_queue_xmit(skb); 213 } 214 215 static void lapbeth_connected(struct net_device *dev, int reason) 216 { 217 unsigned char *ptr; 218 struct sk_buff *skb = dev_alloc_skb(1); 219 220 if (!skb) { 221 pr_err("out of memory\n"); 222 return; 223 } 224 225 ptr = skb_put(skb, 1); 226 *ptr = X25_IFACE_CONNECT; 227 228 skb->protocol = x25_type_trans(skb, dev); 229 netif_rx(skb); 230 } 231 232 static void lapbeth_disconnected(struct net_device *dev, int reason) 233 { 234 unsigned char *ptr; 235 struct sk_buff *skb = dev_alloc_skb(1); 236 237 if (!skb) { 238 pr_err("out of memory\n"); 239 return; 240 } 241 242 ptr = skb_put(skb, 1); 243 *ptr = X25_IFACE_DISCONNECT; 244 245 skb->protocol = x25_type_trans(skb, dev); 246 netif_rx(skb); 247 } 248 249 /* 250 * Set AX.25 callsign 251 */ 252 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 253 { 254 struct sockaddr *sa = addr; 255 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 256 return 0; 257 } 258 259 260 static const struct lapb_register_struct lapbeth_callbacks = { 261 .connect_confirmation = lapbeth_connected, 262 .connect_indication = lapbeth_connected, 263 .disconnect_confirmation = lapbeth_disconnected, 264 .disconnect_indication = lapbeth_disconnected, 265 .data_indication = lapbeth_data_indication, 266 .data_transmit = lapbeth_data_transmit, 267 }; 268 269 /* 270 * open/close a device 271 */ 272 static int lapbeth_open(struct net_device *dev) 273 { 274 int err; 275 276 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 277 pr_err("lapb_register error: %d\n", err); 278 return -ENODEV; 279 } 280 281 netif_start_queue(dev); 282 return 0; 283 } 284 285 static int lapbeth_close(struct net_device *dev) 286 { 287 int err; 288 289 netif_stop_queue(dev); 290 291 if ((err = lapb_unregister(dev)) != LAPB_OK) 292 pr_err("lapb_unregister error: %d\n", err); 293 294 return 0; 295 } 296 297 /* ------------------------------------------------------------------------ */ 298 299 static const struct net_device_ops lapbeth_netdev_ops = { 300 .ndo_open = lapbeth_open, 301 .ndo_stop = lapbeth_close, 302 .ndo_start_xmit = lapbeth_xmit, 303 .ndo_set_mac_address = lapbeth_set_mac_address, 304 }; 305 306 static void lapbeth_setup(struct net_device *dev) 307 { 308 dev->netdev_ops = &lapbeth_netdev_ops; 309 dev->destructor = free_netdev; 310 dev->type = ARPHRD_X25; 311 dev->hard_header_len = 3; 312 dev->mtu = 1000; 313 dev->addr_len = 0; 314 } 315 316 /* 317 * Setup a new device. 318 */ 319 static int lapbeth_new_device(struct net_device *dev) 320 { 321 struct net_device *ndev; 322 struct lapbethdev *lapbeth; 323 int rc = -ENOMEM; 324 325 ASSERT_RTNL(); 326 327 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 328 lapbeth_setup); 329 if (!ndev) 330 goto out; 331 332 lapbeth = netdev_priv(ndev); 333 lapbeth->axdev = ndev; 334 335 dev_hold(dev); 336 lapbeth->ethdev = dev; 337 338 rc = -EIO; 339 if (register_netdevice(ndev)) 340 goto fail; 341 342 list_add_rcu(&lapbeth->node, &lapbeth_devices); 343 rc = 0; 344 out: 345 return rc; 346 fail: 347 dev_put(dev); 348 free_netdev(ndev); 349 kfree(lapbeth); 350 goto out; 351 } 352 353 /* 354 * Free a lapb network device. 355 */ 356 static void lapbeth_free_device(struct lapbethdev *lapbeth) 357 { 358 dev_put(lapbeth->ethdev); 359 list_del_rcu(&lapbeth->node); 360 unregister_netdevice(lapbeth->axdev); 361 } 362 363 /* 364 * Handle device status changes. 365 * 366 * Called from notifier with RTNL held. 367 */ 368 static int lapbeth_device_event(struct notifier_block *this, 369 unsigned long event, void *ptr) 370 { 371 struct lapbethdev *lapbeth; 372 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 373 374 if (dev_net(dev) != &init_net) 375 return NOTIFY_DONE; 376 377 if (!dev_is_ethdev(dev)) 378 return NOTIFY_DONE; 379 380 switch (event) { 381 case NETDEV_UP: 382 /* New ethernet device -> new LAPB interface */ 383 if (lapbeth_get_x25_dev(dev) == NULL) 384 lapbeth_new_device(dev); 385 break; 386 case NETDEV_DOWN: 387 /* ethernet device closed -> close LAPB interface */ 388 lapbeth = lapbeth_get_x25_dev(dev); 389 if (lapbeth) 390 dev_close(lapbeth->axdev); 391 break; 392 case NETDEV_UNREGISTER: 393 /* ethernet device disappears -> remove LAPB interface */ 394 lapbeth = lapbeth_get_x25_dev(dev); 395 if (lapbeth) 396 lapbeth_free_device(lapbeth); 397 break; 398 } 399 400 return NOTIFY_DONE; 401 } 402 403 /* ------------------------------------------------------------------------ */ 404 405 static struct packet_type lapbeth_packet_type __read_mostly = { 406 .type = cpu_to_be16(ETH_P_DEC), 407 .func = lapbeth_rcv, 408 }; 409 410 static struct notifier_block lapbeth_dev_notifier = { 411 .notifier_call = lapbeth_device_event, 412 }; 413 414 static const char banner[] __initconst = 415 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 416 417 static int __init lapbeth_init_driver(void) 418 { 419 dev_add_pack(&lapbeth_packet_type); 420 421 register_netdevice_notifier(&lapbeth_dev_notifier); 422 423 printk(banner); 424 425 return 0; 426 } 427 module_init(lapbeth_init_driver); 428 429 static void __exit lapbeth_cleanup_driver(void) 430 { 431 struct lapbethdev *lapbeth; 432 struct list_head *entry, *tmp; 433 434 dev_remove_pack(&lapbeth_packet_type); 435 unregister_netdevice_notifier(&lapbeth_dev_notifier); 436 437 rtnl_lock(); 438 list_for_each_safe(entry, tmp, &lapbeth_devices) { 439 lapbeth = list_entry(entry, struct lapbethdev, node); 440 441 dev_put(lapbeth->ethdev); 442 unregister_netdevice(lapbeth->axdev); 443 } 444 rtnl_unlock(); 445 } 446 module_exit(lapbeth_cleanup_driver); 447 448 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 449 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 450 MODULE_LICENSE("GPL"); 451