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