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