1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * "LAPB via ethernet" driver release 001 4 * 5 * This code REQUIRES 2.1.15 or higher/ NET3.038 6 * 7 * This is a "pseudo" network driver to allow LAPB over Ethernet. 8 * 9 * This driver can use any ethernet destination address, and can be 10 * limited to accept frames from one dedicated ethernet card only. 11 * 12 * History 13 * LAPBETH 001 Jonathan Naylor Cloned from bpqether.c 14 * 2000-10-29 Henner Eisen lapb_data_indication() return status. 15 * 2000-11-14 Henner Eisen dev_hold/put, NETDEV_GOING_DOWN support 16 */ 17 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 19 20 #include <linux/errno.h> 21 #include <linux/types.h> 22 #include <linux/socket.h> 23 #include <linux/in.h> 24 #include <linux/slab.h> 25 #include <linux/kernel.h> 26 #include <linux/string.h> 27 #include <linux/net.h> 28 #include <linux/inet.h> 29 #include <linux/netdevice.h> 30 #include <linux/if_arp.h> 31 #include <linux/skbuff.h> 32 #include <net/sock.h> 33 #include <linux/uaccess.h> 34 #include <linux/mm.h> 35 #include <linux/interrupt.h> 36 #include <linux/notifier.h> 37 #include <linux/stat.h> 38 #include <linux/module.h> 39 #include <linux/lapb.h> 40 #include <linux/init.h> 41 42 #include <net/x25device.h> 43 44 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }; 45 46 /* If this number is made larger, check that the temporary string buffer 47 * in lapbeth_new_device is large enough to store the probe device name.*/ 48 #define MAXLAPBDEV 100 49 50 struct lapbethdev { 51 struct list_head node; 52 struct net_device *ethdev; /* link to ethernet device */ 53 struct net_device *axdev; /* lapbeth device (lapb#) */ 54 }; 55 56 static LIST_HEAD(lapbeth_devices); 57 58 static void lapbeth_connected(struct net_device *dev, int reason); 59 static void lapbeth_disconnected(struct net_device *dev, int reason); 60 61 /* ------------------------------------------------------------------------ */ 62 63 /* 64 * Get the LAPB device for the ethernet device 65 */ 66 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev) 67 { 68 struct lapbethdev *lapbeth; 69 70 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) { 71 if (lapbeth->ethdev == dev) 72 return lapbeth; 73 } 74 return NULL; 75 } 76 77 static __inline__ int dev_is_ethdev(struct net_device *dev) 78 { 79 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 80 } 81 82 /* ------------------------------------------------------------------------ */ 83 84 /* 85 * Receive a LAPB frame via an ethernet interface. 86 */ 87 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev) 88 { 89 int len, err; 90 struct lapbethdev *lapbeth; 91 92 if (dev_net(dev) != &init_net) 93 goto drop; 94 95 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 96 return NET_RX_DROP; 97 98 if (!pskb_may_pull(skb, 2)) 99 goto drop; 100 101 rcu_read_lock(); 102 lapbeth = lapbeth_get_x25_dev(dev); 103 if (!lapbeth) 104 goto drop_unlock; 105 if (!netif_running(lapbeth->axdev)) 106 goto drop_unlock; 107 108 len = skb->data[0] + skb->data[1] * 256; 109 dev->stats.rx_packets++; 110 dev->stats.rx_bytes += len; 111 112 skb_pull(skb, 2); /* Remove the length bytes */ 113 skb_trim(skb, len); /* Set the length of the data */ 114 115 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) { 116 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err); 117 goto drop_unlock; 118 } 119 out: 120 rcu_read_unlock(); 121 return 0; 122 drop_unlock: 123 kfree_skb(skb); 124 goto out; 125 drop: 126 kfree_skb(skb); 127 return 0; 128 } 129 130 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) 131 { 132 unsigned char *ptr; 133 134 if (skb_cow(skb, 1)) { 135 kfree_skb(skb); 136 return NET_RX_DROP; 137 } 138 139 skb_push(skb, 1); 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 /* There should be a pseudo header of 1 byte added by upper layers. 164 * Check to make sure it is there before reading it. 165 */ 166 if (skb->len < 1) 167 goto drop; 168 169 switch (skb->data[0]) { 170 case X25_IFACE_DATA: 171 break; 172 case X25_IFACE_CONNECT: 173 err = lapb_connect_request(dev); 174 if (err == LAPB_CONNECTED) 175 lapbeth_connected(dev, LAPB_OK); 176 else if (err != LAPB_OK) 177 pr_err("lapb_connect_request error: %d\n", err); 178 goto drop; 179 case X25_IFACE_DISCONNECT: 180 err = lapb_disconnect_request(dev); 181 if (err == LAPB_NOTCONNECTED) 182 lapbeth_disconnected(dev, LAPB_OK); 183 else if (err != LAPB_OK) 184 pr_err("lapb_disconnect_request err: %d\n", err); 185 fallthrough; 186 default: 187 goto drop; 188 } 189 190 skb_pull(skb, 1); 191 192 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) { 193 pr_err("lapb_data_request error - %d\n", err); 194 goto drop; 195 } 196 out: 197 return NETDEV_TX_OK; 198 drop: 199 kfree_skb(skb); 200 goto out; 201 } 202 203 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 204 { 205 struct lapbethdev *lapbeth = netdev_priv(ndev); 206 unsigned char *ptr; 207 struct net_device *dev; 208 int size = skb->len; 209 210 ptr = skb_push(skb, 2); 211 212 *ptr++ = size % 256; 213 *ptr++ = size / 256; 214 215 ndev->stats.tx_packets++; 216 ndev->stats.tx_bytes += size; 217 218 skb->dev = dev = lapbeth->ethdev; 219 220 skb->protocol = htons(ETH_P_DEC); 221 222 skb_reset_network_header(skb); 223 224 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 225 226 dev_queue_xmit(skb); 227 } 228 229 static void lapbeth_connected(struct net_device *dev, int reason) 230 { 231 unsigned char *ptr; 232 struct sk_buff *skb = dev_alloc_skb(1); 233 234 if (!skb) { 235 pr_err("out of memory\n"); 236 return; 237 } 238 239 ptr = skb_put(skb, 1); 240 *ptr = X25_IFACE_CONNECT; 241 242 skb->protocol = x25_type_trans(skb, dev); 243 netif_rx(skb); 244 } 245 246 static void lapbeth_disconnected(struct net_device *dev, int reason) 247 { 248 unsigned char *ptr; 249 struct sk_buff *skb = dev_alloc_skb(1); 250 251 if (!skb) { 252 pr_err("out of memory\n"); 253 return; 254 } 255 256 ptr = skb_put(skb, 1); 257 *ptr = X25_IFACE_DISCONNECT; 258 259 skb->protocol = x25_type_trans(skb, dev); 260 netif_rx(skb); 261 } 262 263 /* 264 * Set AX.25 callsign 265 */ 266 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 267 { 268 struct sockaddr *sa = addr; 269 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 270 return 0; 271 } 272 273 274 static const struct lapb_register_struct lapbeth_callbacks = { 275 .connect_confirmation = lapbeth_connected, 276 .connect_indication = lapbeth_connected, 277 .disconnect_confirmation = lapbeth_disconnected, 278 .disconnect_indication = lapbeth_disconnected, 279 .data_indication = lapbeth_data_indication, 280 .data_transmit = lapbeth_data_transmit, 281 }; 282 283 /* 284 * open/close a device 285 */ 286 static int lapbeth_open(struct net_device *dev) 287 { 288 int err; 289 290 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 291 pr_err("lapb_register error: %d\n", err); 292 return -ENODEV; 293 } 294 295 return 0; 296 } 297 298 static int lapbeth_close(struct net_device *dev) 299 { 300 int err; 301 302 if ((err = lapb_unregister(dev)) != LAPB_OK) 303 pr_err("lapb_unregister error: %d\n", err); 304 305 return 0; 306 } 307 308 /* ------------------------------------------------------------------------ */ 309 310 static const struct net_device_ops lapbeth_netdev_ops = { 311 .ndo_open = lapbeth_open, 312 .ndo_stop = lapbeth_close, 313 .ndo_start_xmit = lapbeth_xmit, 314 .ndo_set_mac_address = lapbeth_set_mac_address, 315 }; 316 317 static void lapbeth_setup(struct net_device *dev) 318 { 319 dev->netdev_ops = &lapbeth_netdev_ops; 320 dev->needs_free_netdev = true; 321 dev->type = ARPHRD_X25; 322 dev->hard_header_len = 0; 323 dev->mtu = 1000; 324 dev->addr_len = 0; 325 } 326 327 /* 328 * Setup a new device. 329 */ 330 static int lapbeth_new_device(struct net_device *dev) 331 { 332 struct net_device *ndev; 333 struct lapbethdev *lapbeth; 334 int rc = -ENOMEM; 335 336 ASSERT_RTNL(); 337 338 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 339 lapbeth_setup); 340 if (!ndev) 341 goto out; 342 343 /* When transmitting data: 344 * first this driver removes a pseudo header of 1 byte, 345 * then the lapb module prepends an LAPB header of at most 3 bytes, 346 * then this driver prepends a length field of 2 bytes, 347 * then the underlying Ethernet device prepends its own header. 348 */ 349 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len 350 + dev->needed_headroom; 351 ndev->needed_tailroom = dev->needed_tailroom; 352 353 lapbeth = netdev_priv(ndev); 354 lapbeth->axdev = ndev; 355 356 dev_hold(dev); 357 lapbeth->ethdev = dev; 358 359 rc = -EIO; 360 if (register_netdevice(ndev)) 361 goto fail; 362 363 list_add_rcu(&lapbeth->node, &lapbeth_devices); 364 rc = 0; 365 out: 366 return rc; 367 fail: 368 dev_put(dev); 369 free_netdev(ndev); 370 goto out; 371 } 372 373 /* 374 * Free a lapb network device. 375 */ 376 static void lapbeth_free_device(struct lapbethdev *lapbeth) 377 { 378 dev_put(lapbeth->ethdev); 379 list_del_rcu(&lapbeth->node); 380 unregister_netdevice(lapbeth->axdev); 381 } 382 383 /* 384 * Handle device status changes. 385 * 386 * Called from notifier with RTNL held. 387 */ 388 static int lapbeth_device_event(struct notifier_block *this, 389 unsigned long event, void *ptr) 390 { 391 struct lapbethdev *lapbeth; 392 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 393 394 if (dev_net(dev) != &init_net) 395 return NOTIFY_DONE; 396 397 if (!dev_is_ethdev(dev)) 398 return NOTIFY_DONE; 399 400 switch (event) { 401 case NETDEV_UP: 402 /* New ethernet device -> new LAPB interface */ 403 if (lapbeth_get_x25_dev(dev) == NULL) 404 lapbeth_new_device(dev); 405 break; 406 case NETDEV_DOWN: 407 /* ethernet device closed -> close LAPB interface */ 408 lapbeth = lapbeth_get_x25_dev(dev); 409 if (lapbeth) 410 dev_close(lapbeth->axdev); 411 break; 412 case NETDEV_UNREGISTER: 413 /* ethernet device disappears -> remove LAPB interface */ 414 lapbeth = lapbeth_get_x25_dev(dev); 415 if (lapbeth) 416 lapbeth_free_device(lapbeth); 417 break; 418 } 419 420 return NOTIFY_DONE; 421 } 422 423 /* ------------------------------------------------------------------------ */ 424 425 static struct packet_type lapbeth_packet_type __read_mostly = { 426 .type = cpu_to_be16(ETH_P_DEC), 427 .func = lapbeth_rcv, 428 }; 429 430 static struct notifier_block lapbeth_dev_notifier = { 431 .notifier_call = lapbeth_device_event, 432 }; 433 434 static const char banner[] __initconst = 435 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 436 437 static int __init lapbeth_init_driver(void) 438 { 439 dev_add_pack(&lapbeth_packet_type); 440 441 register_netdevice_notifier(&lapbeth_dev_notifier); 442 443 printk(banner); 444 445 return 0; 446 } 447 module_init(lapbeth_init_driver); 448 449 static void __exit lapbeth_cleanup_driver(void) 450 { 451 struct lapbethdev *lapbeth; 452 struct list_head *entry, *tmp; 453 454 dev_remove_pack(&lapbeth_packet_type); 455 unregister_netdevice_notifier(&lapbeth_dev_notifier); 456 457 rtnl_lock(); 458 list_for_each_safe(entry, tmp, &lapbeth_devices) { 459 lapbeth = list_entry(entry, struct lapbethdev, node); 460 461 dev_put(lapbeth->ethdev); 462 unregister_netdevice(lapbeth->axdev); 463 } 464 rtnl_unlock(); 465 } 466 module_exit(lapbeth_cleanup_driver); 467 468 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 469 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 470 MODULE_LICENSE("GPL"); 471