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