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 bool up; 55 spinlock_t up_lock; /* Protects "up" */ 56 struct sk_buff_head rx_queue; 57 struct napi_struct napi; 58 }; 59 60 static LIST_HEAD(lapbeth_devices); 61 62 static void lapbeth_connected(struct net_device *dev, int reason); 63 static void lapbeth_disconnected(struct net_device *dev, int reason); 64 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 /* 109 * Receive a LAPB frame via an ethernet interface. 110 */ 111 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, 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 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) 120 return NET_RX_DROP; 121 122 if (!pskb_may_pull(skb, 2)) 123 goto drop; 124 125 rcu_read_lock(); 126 lapbeth = lapbeth_get_x25_dev(dev); 127 if (!lapbeth) 128 goto drop_unlock_rcu; 129 spin_lock_bh(&lapbeth->up_lock); 130 if (!lapbeth->up) 131 goto drop_unlock; 132 133 len = skb->data[0] + skb->data[1] * 256; 134 dev->stats.rx_packets++; 135 dev->stats.rx_bytes += len; 136 137 skb_pull(skb, 2); /* Remove the length bytes */ 138 skb_trim(skb, len); /* Set the length of the data */ 139 140 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) { 141 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err); 142 goto drop_unlock; 143 } 144 out: 145 spin_unlock_bh(&lapbeth->up_lock); 146 rcu_read_unlock(); 147 return 0; 148 drop_unlock: 149 kfree_skb(skb); 150 goto out; 151 drop_unlock_rcu: 152 rcu_read_unlock(); 153 drop: 154 kfree_skb(skb); 155 return 0; 156 } 157 158 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb) 159 { 160 struct lapbethdev *lapbeth = netdev_priv(dev); 161 unsigned char *ptr; 162 163 if (skb_cow(skb, 1)) { 164 kfree_skb(skb); 165 return NET_RX_DROP; 166 } 167 168 skb_push(skb, 1); 169 170 ptr = skb->data; 171 *ptr = X25_IFACE_DATA; 172 173 skb->protocol = x25_type_trans(skb, dev); 174 175 skb_queue_tail(&lapbeth->rx_queue, skb); 176 napi_schedule(&lapbeth->napi); 177 return NET_RX_SUCCESS; 178 } 179 180 /* 181 * Send a LAPB frame via an ethernet interface 182 */ 183 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, 184 struct net_device *dev) 185 { 186 struct lapbethdev *lapbeth = netdev_priv(dev); 187 int err; 188 189 spin_lock_bh(&lapbeth->up_lock); 190 if (!lapbeth->up) 191 goto drop; 192 193 /* There should be a pseudo header of 1 byte added by upper layers. 194 * Check to make sure it is there before reading it. 195 */ 196 if (skb->len < 1) 197 goto drop; 198 199 switch (skb->data[0]) { 200 case X25_IFACE_DATA: 201 break; 202 case X25_IFACE_CONNECT: 203 err = lapb_connect_request(dev); 204 if (err == LAPB_CONNECTED) 205 lapbeth_connected(dev, LAPB_OK); 206 else if (err != LAPB_OK) 207 pr_err("lapb_connect_request error: %d\n", err); 208 goto drop; 209 case X25_IFACE_DISCONNECT: 210 err = lapb_disconnect_request(dev); 211 if (err == LAPB_NOTCONNECTED) 212 lapbeth_disconnected(dev, LAPB_OK); 213 else if (err != LAPB_OK) 214 pr_err("lapb_disconnect_request err: %d\n", err); 215 fallthrough; 216 default: 217 goto drop; 218 } 219 220 skb_pull(skb, 1); 221 222 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) { 223 pr_err("lapb_data_request error - %d\n", err); 224 goto drop; 225 } 226 out: 227 spin_unlock_bh(&lapbeth->up_lock); 228 return NETDEV_TX_OK; 229 drop: 230 kfree_skb(skb); 231 goto out; 232 } 233 234 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 235 { 236 struct lapbethdev *lapbeth = netdev_priv(ndev); 237 unsigned char *ptr; 238 struct net_device *dev; 239 int size = skb->len; 240 241 ptr = skb_push(skb, 2); 242 243 *ptr++ = size % 256; 244 *ptr++ = size / 256; 245 246 ndev->stats.tx_packets++; 247 ndev->stats.tx_bytes += size; 248 249 skb->dev = dev = lapbeth->ethdev; 250 251 skb->protocol = htons(ETH_P_DEC); 252 253 skb_reset_network_header(skb); 254 255 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 256 257 dev_queue_xmit(skb); 258 } 259 260 static void lapbeth_connected(struct net_device *dev, int reason) 261 { 262 struct lapbethdev *lapbeth = netdev_priv(dev); 263 unsigned char *ptr; 264 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC); 265 266 if (!skb) { 267 pr_err("out of memory\n"); 268 return; 269 } 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 pr_err("out of memory\n"); 288 return; 289 } 290 291 ptr = skb_put(skb, 1); 292 *ptr = X25_IFACE_DISCONNECT; 293 294 skb->protocol = x25_type_trans(skb, dev); 295 296 skb_queue_tail(&lapbeth->rx_queue, skb); 297 napi_schedule(&lapbeth->napi); 298 } 299 300 /* 301 * Set AX.25 callsign 302 */ 303 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 304 { 305 struct sockaddr *sa = addr; 306 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 307 return 0; 308 } 309 310 311 static const struct lapb_register_struct lapbeth_callbacks = { 312 .connect_confirmation = lapbeth_connected, 313 .connect_indication = lapbeth_connected, 314 .disconnect_confirmation = lapbeth_disconnected, 315 .disconnect_indication = lapbeth_disconnected, 316 .data_indication = lapbeth_data_indication, 317 .data_transmit = lapbeth_data_transmit, 318 }; 319 320 /* 321 * open/close a device 322 */ 323 static int lapbeth_open(struct net_device *dev) 324 { 325 struct lapbethdev *lapbeth = netdev_priv(dev); 326 int err; 327 328 napi_enable(&lapbeth->napi); 329 330 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 331 pr_err("lapb_register error: %d\n", err); 332 return -ENODEV; 333 } 334 335 spin_lock_bh(&lapbeth->up_lock); 336 lapbeth->up = true; 337 spin_unlock_bh(&lapbeth->up_lock); 338 339 return 0; 340 } 341 342 static int lapbeth_close(struct net_device *dev) 343 { 344 struct lapbethdev *lapbeth = netdev_priv(dev); 345 int err; 346 347 spin_lock_bh(&lapbeth->up_lock); 348 lapbeth->up = false; 349 spin_unlock_bh(&lapbeth->up_lock); 350 351 if ((err = lapb_unregister(dev)) != 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 dev->netdev_ops = &lapbeth_netdev_ops; 371 dev->needs_free_netdev = true; 372 dev->type = ARPHRD_X25; 373 dev->hard_header_len = 0; 374 dev->mtu = 1000; 375 dev->addr_len = 0; 376 } 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 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 390 lapbeth_setup); 391 if (!ndev) 392 goto out; 393 394 /* When transmitting data: 395 * first this driver removes a pseudo header of 1 byte, 396 * then the lapb module prepends an LAPB header of at most 3 bytes, 397 * then this driver prepends a length field of 2 bytes, 398 * then the underlying Ethernet device prepends its own header. 399 */ 400 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len 401 + dev->needed_headroom; 402 ndev->needed_tailroom = dev->needed_tailroom; 403 404 lapbeth = netdev_priv(ndev); 405 lapbeth->axdev = ndev; 406 407 dev_hold(dev); 408 lapbeth->ethdev = dev; 409 410 lapbeth->up = false; 411 spin_lock_init(&lapbeth->up_lock); 412 413 skb_queue_head_init(&lapbeth->rx_queue); 414 netif_napi_add(ndev, &lapbeth->napi, lapbeth_napi_poll, 16); 415 416 rc = -EIO; 417 if (register_netdevice(ndev)) 418 goto fail; 419 420 list_add_rcu(&lapbeth->node, &lapbeth_devices); 421 rc = 0; 422 out: 423 return rc; 424 fail: 425 dev_put(dev); 426 free_netdev(ndev); 427 goto out; 428 } 429 430 /* 431 * Free a lapb network device. 432 */ 433 static void lapbeth_free_device(struct lapbethdev *lapbeth) 434 { 435 dev_put(lapbeth->ethdev); 436 list_del_rcu(&lapbeth->node); 437 unregister_netdevice(lapbeth->axdev); 438 } 439 440 /* 441 * Handle device status changes. 442 * 443 * Called from notifier with RTNL held. 444 */ 445 static int lapbeth_device_event(struct notifier_block *this, 446 unsigned long event, void *ptr) 447 { 448 struct lapbethdev *lapbeth; 449 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 450 451 if (dev_net(dev) != &init_net) 452 return NOTIFY_DONE; 453 454 if (!dev_is_ethdev(dev)) 455 return NOTIFY_DONE; 456 457 switch (event) { 458 case NETDEV_UP: 459 /* New ethernet device -> new LAPB interface */ 460 if (lapbeth_get_x25_dev(dev) == NULL) 461 lapbeth_new_device(dev); 462 break; 463 case NETDEV_GOING_DOWN: 464 /* ethernet device closes -> close LAPB interface */ 465 lapbeth = lapbeth_get_x25_dev(dev); 466 if (lapbeth) 467 dev_close(lapbeth->axdev); 468 break; 469 case NETDEV_UNREGISTER: 470 /* ethernet device disappears -> remove LAPB interface */ 471 lapbeth = lapbeth_get_x25_dev(dev); 472 if (lapbeth) 473 lapbeth_free_device(lapbeth); 474 break; 475 } 476 477 return NOTIFY_DONE; 478 } 479 480 /* ------------------------------------------------------------------------ */ 481 482 static struct packet_type lapbeth_packet_type __read_mostly = { 483 .type = cpu_to_be16(ETH_P_DEC), 484 .func = lapbeth_rcv, 485 }; 486 487 static struct notifier_block lapbeth_dev_notifier = { 488 .notifier_call = lapbeth_device_event, 489 }; 490 491 static const char banner[] __initconst = 492 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 493 494 static int __init lapbeth_init_driver(void) 495 { 496 dev_add_pack(&lapbeth_packet_type); 497 498 register_netdevice_notifier(&lapbeth_dev_notifier); 499 500 printk(banner); 501 502 return 0; 503 } 504 module_init(lapbeth_init_driver); 505 506 static void __exit lapbeth_cleanup_driver(void) 507 { 508 struct lapbethdev *lapbeth; 509 struct list_head *entry, *tmp; 510 511 dev_remove_pack(&lapbeth_packet_type); 512 unregister_netdevice_notifier(&lapbeth_dev_notifier); 513 514 rtnl_lock(); 515 list_for_each_safe(entry, tmp, &lapbeth_devices) { 516 lapbeth = list_entry(entry, struct lapbethdev, node); 517 518 dev_put(lapbeth->ethdev); 519 unregister_netdevice(lapbeth->axdev); 520 } 521 rtnl_unlock(); 522 } 523 module_exit(lapbeth_cleanup_driver); 524 525 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 526 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 527 MODULE_LICENSE("GPL"); 528