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/netdev_lock.h> 43 #include <net/x25device.h> 44 45 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }; 46 47 /* If this number is made larger, check that the temporary string buffer 48 * in lapbeth_new_device is large enough to store the probe device name. 49 */ 50 #define MAXLAPBDEV 100 51 52 struct lapbethdev { 53 struct list_head node; 54 struct net_device *ethdev; /* link to ethernet device */ 55 struct net_device *axdev; /* lapbeth device (lapb#) */ 56 bool up; 57 spinlock_t up_lock; /* Protects "up" */ 58 struct sk_buff_head rx_queue; 59 struct napi_struct napi; 60 }; 61 62 static LIST_HEAD(lapbeth_devices); 63 64 static void lapbeth_connected(struct net_device *dev, int reason); 65 static void lapbeth_disconnected(struct net_device *dev, int reason); 66 67 /* ------------------------------------------------------------------------ */ 68 69 /* Get the LAPB device for the ethernet device 70 */ 71 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev) 72 { 73 struct lapbethdev *lapbeth; 74 75 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) { 76 if (lapbeth->ethdev == dev) 77 return lapbeth; 78 } 79 return NULL; 80 } 81 82 static __inline__ int dev_is_ethdev(struct net_device *dev) 83 { 84 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5); 85 } 86 87 /* ------------------------------------------------------------------------ */ 88 89 static int lapbeth_napi_poll(struct napi_struct *napi, int budget) 90 { 91 struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev, 92 napi); 93 struct sk_buff *skb; 94 int processed = 0; 95 96 for (; processed < budget; ++processed) { 97 skb = skb_dequeue(&lapbeth->rx_queue); 98 if (!skb) 99 break; 100 netif_receive_skb_core(skb); 101 } 102 103 if (processed < budget) 104 napi_complete(napi); 105 106 return processed; 107 } 108 109 /* Receive a LAPB frame via an ethernet interface. 110 */ 111 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, 112 struct packet_type *ptype, struct net_device *orig_dev) 113 { 114 int len, err; 115 struct lapbethdev *lapbeth; 116 117 if (dev_net(dev) != &init_net) 118 goto drop; 119 120 skb = skb_share_check(skb, GFP_ATOMIC); 121 if (!skb) 122 return NET_RX_DROP; 123 124 if (!pskb_may_pull(skb, 2)) 125 goto drop; 126 127 rcu_read_lock(); 128 lapbeth = lapbeth_get_x25_dev(dev); 129 if (!lapbeth) 130 goto drop_unlock_rcu; 131 spin_lock_bh(&lapbeth->up_lock); 132 if (!lapbeth->up) 133 goto drop_unlock; 134 135 len = skb->data[0] + skb->data[1] * 256; 136 dev->stats.rx_packets++; 137 dev->stats.rx_bytes += len; 138 139 skb_pull(skb, 2); /* Remove the length bytes */ 140 skb_trim(skb, len); /* Set the length of the data */ 141 142 err = lapb_data_received(lapbeth->axdev, skb); 143 if (err != LAPB_OK) { 144 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err); 145 goto drop_unlock; 146 } 147 out: 148 spin_unlock_bh(&lapbeth->up_lock); 149 rcu_read_unlock(); 150 return 0; 151 drop_unlock: 152 kfree_skb(skb); 153 goto out; 154 drop_unlock_rcu: 155 rcu_read_unlock(); 156 drop: 157 kfree_skb(skb); 158 return 0; 159 } 160 161 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) 162 { 163 struct lapbethdev *lapbeth = netdev_priv(dev); 164 unsigned char *ptr; 165 166 if (skb_cow(skb, 1)) { 167 kfree_skb(skb); 168 return NET_RX_DROP; 169 } 170 171 skb_push(skb, 1); 172 173 ptr = skb->data; 174 *ptr = X25_IFACE_DATA; 175 176 skb->protocol = x25_type_trans(skb, dev); 177 178 skb_queue_tail(&lapbeth->rx_queue, skb); 179 napi_schedule(&lapbeth->napi); 180 return NET_RX_SUCCESS; 181 } 182 183 /* Send a LAPB frame via an ethernet interface 184 */ 185 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, 186 struct net_device *dev) 187 { 188 struct lapbethdev *lapbeth = netdev_priv(dev); 189 int err; 190 191 spin_lock_bh(&lapbeth->up_lock); 192 if (!lapbeth->up) 193 goto drop; 194 195 /* There should be a pseudo header of 1 byte added by upper layers. 196 * Check to make sure it is there before reading it. 197 */ 198 if (skb->len < 1) 199 goto drop; 200 201 switch (skb->data[0]) { 202 case X25_IFACE_DATA: 203 break; 204 case X25_IFACE_CONNECT: 205 err = lapb_connect_request(dev); 206 if (err == LAPB_CONNECTED) 207 lapbeth_connected(dev, LAPB_OK); 208 else if (err != LAPB_OK) 209 pr_err("lapb_connect_request error: %d\n", err); 210 goto drop; 211 case X25_IFACE_DISCONNECT: 212 err = lapb_disconnect_request(dev); 213 if (err == LAPB_NOTCONNECTED) 214 lapbeth_disconnected(dev, LAPB_OK); 215 else if (err != LAPB_OK) 216 pr_err("lapb_disconnect_request err: %d\n", err); 217 fallthrough; 218 default: 219 goto drop; 220 } 221 222 skb_pull(skb, 1); 223 224 err = lapb_data_request(dev, skb); 225 if (err != LAPB_OK) { 226 pr_err("lapb_data_request error - %d\n", err); 227 goto drop; 228 } 229 out: 230 spin_unlock_bh(&lapbeth->up_lock); 231 return NETDEV_TX_OK; 232 drop: 233 kfree_skb(skb); 234 goto out; 235 } 236 237 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 238 { 239 struct lapbethdev *lapbeth = netdev_priv(ndev); 240 unsigned char *ptr; 241 struct net_device *dev; 242 int size = skb->len; 243 244 ptr = skb_push(skb, 2); 245 246 *ptr++ = size % 256; 247 *ptr++ = size / 256; 248 249 ndev->stats.tx_packets++; 250 ndev->stats.tx_bytes += size; 251 252 skb->dev = dev = lapbeth->ethdev; 253 254 skb->protocol = htons(ETH_P_DEC); 255 256 skb_reset_network_header(skb); 257 258 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 259 260 dev_queue_xmit(skb); 261 } 262 263 static void lapbeth_connected(struct net_device *dev, int reason) 264 { 265 struct lapbethdev *lapbeth = netdev_priv(dev); 266 unsigned char *ptr; 267 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC); 268 269 if (!skb) 270 return; 271 272 ptr = skb_put(skb, 1); 273 *ptr = X25_IFACE_CONNECT; 274 275 skb->protocol = x25_type_trans(skb, dev); 276 277 skb_queue_tail(&lapbeth->rx_queue, skb); 278 napi_schedule(&lapbeth->napi); 279 } 280 281 static void lapbeth_disconnected(struct net_device *dev, int reason) 282 { 283 struct lapbethdev *lapbeth = netdev_priv(dev); 284 unsigned char *ptr; 285 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC); 286 287 if (!skb) 288 return; 289 290 ptr = skb_put(skb, 1); 291 *ptr = X25_IFACE_DISCONNECT; 292 293 skb->protocol = x25_type_trans(skb, dev); 294 295 skb_queue_tail(&lapbeth->rx_queue, skb); 296 napi_schedule(&lapbeth->napi); 297 } 298 299 /* Set AX.25 callsign 300 */ 301 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 302 { 303 struct sockaddr *sa = addr; 304 305 dev_addr_set(dev, sa->sa_data); 306 return 0; 307 } 308 309 static const struct lapb_register_struct lapbeth_callbacks = { 310 .connect_confirmation = lapbeth_connected, 311 .connect_indication = lapbeth_connected, 312 .disconnect_confirmation = lapbeth_disconnected, 313 .disconnect_indication = lapbeth_disconnected, 314 .data_indication = lapbeth_data_indication, 315 .data_transmit = lapbeth_data_transmit, 316 }; 317 318 /* open/close a device 319 */ 320 static int lapbeth_open(struct net_device *dev) 321 { 322 struct lapbethdev *lapbeth = netdev_priv(dev); 323 int err; 324 325 napi_enable(&lapbeth->napi); 326 327 err = lapb_register(dev, &lapbeth_callbacks); 328 if (err != LAPB_OK) { 329 napi_disable(&lapbeth->napi); 330 pr_err("lapb_register error: %d\n", err); 331 return -ENODEV; 332 } 333 334 spin_lock_bh(&lapbeth->up_lock); 335 lapbeth->up = true; 336 spin_unlock_bh(&lapbeth->up_lock); 337 338 return 0; 339 } 340 341 static int lapbeth_close(struct net_device *dev) 342 { 343 struct lapbethdev *lapbeth = netdev_priv(dev); 344 int err; 345 346 spin_lock_bh(&lapbeth->up_lock); 347 lapbeth->up = false; 348 spin_unlock_bh(&lapbeth->up_lock); 349 350 err = lapb_unregister(dev); 351 if (err != LAPB_OK) 352 pr_err("lapb_unregister error: %d\n", err); 353 354 napi_disable(&lapbeth->napi); 355 356 return 0; 357 } 358 359 /* ------------------------------------------------------------------------ */ 360 361 static const struct net_device_ops lapbeth_netdev_ops = { 362 .ndo_open = lapbeth_open, 363 .ndo_stop = lapbeth_close, 364 .ndo_start_xmit = lapbeth_xmit, 365 .ndo_set_mac_address = lapbeth_set_mac_address, 366 }; 367 368 static void lapbeth_setup(struct net_device *dev) 369 { 370 netdev_lockdep_set_classes(dev); 371 dev->netdev_ops = &lapbeth_netdev_ops; 372 dev->needs_free_netdev = true; 373 dev->type = ARPHRD_X25; 374 dev->hard_header_len = 0; 375 dev->mtu = 1000; 376 dev->addr_len = 0; 377 } 378 379 /* Setup a new device. 380 */ 381 static int lapbeth_new_device(struct net_device *dev) 382 { 383 struct net_device *ndev; 384 struct lapbethdev *lapbeth; 385 int rc = -ENOMEM; 386 387 ASSERT_RTNL(); 388 389 if (dev->type != ARPHRD_ETHER) 390 return -EINVAL; 391 392 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 393 lapbeth_setup); 394 if (!ndev) 395 goto out; 396 397 /* When transmitting data: 398 * first this driver removes a pseudo header of 1 byte, 399 * then the lapb module prepends an LAPB header of at most 3 bytes, 400 * then this driver prepends a length field of 2 bytes, 401 * then the underlying Ethernet device prepends its own header. 402 */ 403 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len 404 + dev->needed_headroom; 405 ndev->needed_tailroom = dev->needed_tailroom; 406 407 lapbeth = netdev_priv(ndev); 408 lapbeth->axdev = ndev; 409 410 dev_hold(dev); 411 lapbeth->ethdev = dev; 412 413 lapbeth->up = false; 414 spin_lock_init(&lapbeth->up_lock); 415 416 skb_queue_head_init(&lapbeth->rx_queue); 417 netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16); 418 419 rc = -EIO; 420 if (register_netdevice(ndev)) 421 goto fail; 422 423 list_add_rcu(&lapbeth->node, &lapbeth_devices); 424 rc = 0; 425 out: 426 return rc; 427 fail: 428 dev_put(dev); 429 free_netdev(ndev); 430 goto out; 431 } 432 433 /* Free a lapb network device. 434 */ 435 static void lapbeth_free_device(struct lapbethdev *lapbeth) 436 { 437 dev_put(lapbeth->ethdev); 438 list_del_rcu(&lapbeth->node); 439 unregister_netdevice(lapbeth->axdev); 440 } 441 442 /* Handle device status changes. 443 * 444 * Called from notifier with RTNL held. 445 */ 446 static int lapbeth_device_event(struct notifier_block *this, 447 unsigned long event, void *ptr) 448 { 449 struct lapbethdev *lapbeth; 450 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 451 452 if (dev_net(dev) != &init_net) 453 return NOTIFY_DONE; 454 455 if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev)) 456 return NOTIFY_DONE; 457 458 switch (event) { 459 case NETDEV_UP: 460 /* New ethernet device -> new LAPB interface */ 461 if (!lapbeth_get_x25_dev(dev)) 462 lapbeth_new_device(dev); 463 break; 464 case NETDEV_GOING_DOWN: 465 /* ethernet device closes -> close LAPB interface */ 466 lapbeth = lapbeth_get_x25_dev(dev); 467 if (lapbeth) 468 dev_close(lapbeth->axdev); 469 break; 470 case NETDEV_UNREGISTER: 471 /* ethernet device disappears -> remove LAPB interface */ 472 lapbeth = lapbeth_get_x25_dev(dev); 473 if (lapbeth) 474 lapbeth_free_device(lapbeth); 475 break; 476 } 477 478 return NOTIFY_DONE; 479 } 480 481 /* ------------------------------------------------------------------------ */ 482 483 static struct packet_type lapbeth_packet_type __read_mostly = { 484 .type = cpu_to_be16(ETH_P_DEC), 485 .func = lapbeth_rcv, 486 }; 487 488 static struct notifier_block lapbeth_dev_notifier = { 489 .notifier_call = lapbeth_device_event, 490 }; 491 492 static const char banner[] __initconst = 493 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 494 495 static int __init lapbeth_init_driver(void) 496 { 497 dev_add_pack(&lapbeth_packet_type); 498 499 register_netdevice_notifier(&lapbeth_dev_notifier); 500 501 printk(banner); 502 503 return 0; 504 } 505 module_init(lapbeth_init_driver); 506 507 static void __exit lapbeth_cleanup_driver(void) 508 { 509 struct lapbethdev *lapbeth; 510 struct list_head *entry, *tmp; 511 512 dev_remove_pack(&lapbeth_packet_type); 513 unregister_netdevice_notifier(&lapbeth_dev_notifier); 514 515 rtnl_lock(); 516 list_for_each_safe(entry, tmp, &lapbeth_devices) { 517 lapbeth = list_entry(entry, struct lapbethdev, node); 518 519 dev_put(lapbeth->ethdev); 520 unregister_netdevice(lapbeth->axdev); 521 } 522 rtnl_unlock(); 523 } 524 module_exit(lapbeth_cleanup_driver); 525 526 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 527 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 528 MODULE_LICENSE("GPL"); 529