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 skb->protocol = htons(ETH_P_X25); 202 203 ptr = skb_push(skb, 2); 204 205 *ptr++ = size % 256; 206 *ptr++ = size / 256; 207 208 ndev->stats.tx_packets++; 209 ndev->stats.tx_bytes += size; 210 211 skb->dev = dev = lapbeth->ethdev; 212 213 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 214 215 dev_queue_xmit(skb); 216 } 217 218 static void lapbeth_connected(struct net_device *dev, int reason) 219 { 220 unsigned char *ptr; 221 struct sk_buff *skb = dev_alloc_skb(1); 222 223 if (!skb) { 224 pr_err("out of memory\n"); 225 return; 226 } 227 228 ptr = skb_put(skb, 1); 229 *ptr = X25_IFACE_CONNECT; 230 231 skb->protocol = x25_type_trans(skb, dev); 232 netif_rx(skb); 233 } 234 235 static void lapbeth_disconnected(struct net_device *dev, int reason) 236 { 237 unsigned char *ptr; 238 struct sk_buff *skb = dev_alloc_skb(1); 239 240 if (!skb) { 241 pr_err("out of memory\n"); 242 return; 243 } 244 245 ptr = skb_put(skb, 1); 246 *ptr = X25_IFACE_DISCONNECT; 247 248 skb->protocol = x25_type_trans(skb, dev); 249 netif_rx(skb); 250 } 251 252 /* 253 * Set AX.25 callsign 254 */ 255 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 256 { 257 struct sockaddr *sa = addr; 258 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 259 return 0; 260 } 261 262 263 static const struct lapb_register_struct lapbeth_callbacks = { 264 .connect_confirmation = lapbeth_connected, 265 .connect_indication = lapbeth_connected, 266 .disconnect_confirmation = lapbeth_disconnected, 267 .disconnect_indication = lapbeth_disconnected, 268 .data_indication = lapbeth_data_indication, 269 .data_transmit = lapbeth_data_transmit, 270 }; 271 272 /* 273 * open/close a device 274 */ 275 static int lapbeth_open(struct net_device *dev) 276 { 277 int err; 278 279 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 280 pr_err("lapb_register error: %d\n", err); 281 return -ENODEV; 282 } 283 284 netif_start_queue(dev); 285 return 0; 286 } 287 288 static int lapbeth_close(struct net_device *dev) 289 { 290 int err; 291 292 netif_stop_queue(dev); 293 294 if ((err = lapb_unregister(dev)) != LAPB_OK) 295 pr_err("lapb_unregister error: %d\n", err); 296 297 return 0; 298 } 299 300 /* ------------------------------------------------------------------------ */ 301 302 static const struct net_device_ops lapbeth_netdev_ops = { 303 .ndo_open = lapbeth_open, 304 .ndo_stop = lapbeth_close, 305 .ndo_start_xmit = lapbeth_xmit, 306 .ndo_set_mac_address = lapbeth_set_mac_address, 307 }; 308 309 static void lapbeth_setup(struct net_device *dev) 310 { 311 dev->netdev_ops = &lapbeth_netdev_ops; 312 dev->needs_free_netdev = true; 313 dev->type = ARPHRD_X25; 314 dev->hard_header_len = 0; 315 dev->mtu = 1000; 316 dev->addr_len = 0; 317 } 318 319 /* 320 * Setup a new device. 321 */ 322 static int lapbeth_new_device(struct net_device *dev) 323 { 324 struct net_device *ndev; 325 struct lapbethdev *lapbeth; 326 int rc = -ENOMEM; 327 328 ASSERT_RTNL(); 329 330 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 331 lapbeth_setup); 332 if (!ndev) 333 goto out; 334 335 /* When transmitting data: 336 * first this driver removes a pseudo header of 1 byte, 337 * then the lapb module prepends an LAPB header of at most 3 bytes, 338 * then this driver prepends a length field of 2 bytes, 339 * then the underlying Ethernet device prepends its own header. 340 */ 341 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len 342 + dev->needed_headroom; 343 344 lapbeth = netdev_priv(ndev); 345 lapbeth->axdev = ndev; 346 347 dev_hold(dev); 348 lapbeth->ethdev = dev; 349 350 rc = -EIO; 351 if (register_netdevice(ndev)) 352 goto fail; 353 354 list_add_rcu(&lapbeth->node, &lapbeth_devices); 355 rc = 0; 356 out: 357 return rc; 358 fail: 359 dev_put(dev); 360 free_netdev(ndev); 361 goto out; 362 } 363 364 /* 365 * Free a lapb network device. 366 */ 367 static void lapbeth_free_device(struct lapbethdev *lapbeth) 368 { 369 dev_put(lapbeth->ethdev); 370 list_del_rcu(&lapbeth->node); 371 unregister_netdevice(lapbeth->axdev); 372 } 373 374 /* 375 * Handle device status changes. 376 * 377 * Called from notifier with RTNL held. 378 */ 379 static int lapbeth_device_event(struct notifier_block *this, 380 unsigned long event, void *ptr) 381 { 382 struct lapbethdev *lapbeth; 383 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 384 385 if (dev_net(dev) != &init_net) 386 return NOTIFY_DONE; 387 388 if (!dev_is_ethdev(dev)) 389 return NOTIFY_DONE; 390 391 switch (event) { 392 case NETDEV_UP: 393 /* New ethernet device -> new LAPB interface */ 394 if (lapbeth_get_x25_dev(dev) == NULL) 395 lapbeth_new_device(dev); 396 break; 397 case NETDEV_DOWN: 398 /* ethernet device closed -> close LAPB interface */ 399 lapbeth = lapbeth_get_x25_dev(dev); 400 if (lapbeth) 401 dev_close(lapbeth->axdev); 402 break; 403 case NETDEV_UNREGISTER: 404 /* ethernet device disappears -> remove LAPB interface */ 405 lapbeth = lapbeth_get_x25_dev(dev); 406 if (lapbeth) 407 lapbeth_free_device(lapbeth); 408 break; 409 } 410 411 return NOTIFY_DONE; 412 } 413 414 /* ------------------------------------------------------------------------ */ 415 416 static struct packet_type lapbeth_packet_type __read_mostly = { 417 .type = cpu_to_be16(ETH_P_DEC), 418 .func = lapbeth_rcv, 419 }; 420 421 static struct notifier_block lapbeth_dev_notifier = { 422 .notifier_call = lapbeth_device_event, 423 }; 424 425 static const char banner[] __initconst = 426 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 427 428 static int __init lapbeth_init_driver(void) 429 { 430 dev_add_pack(&lapbeth_packet_type); 431 432 register_netdevice_notifier(&lapbeth_dev_notifier); 433 434 printk(banner); 435 436 return 0; 437 } 438 module_init(lapbeth_init_driver); 439 440 static void __exit lapbeth_cleanup_driver(void) 441 { 442 struct lapbethdev *lapbeth; 443 struct list_head *entry, *tmp; 444 445 dev_remove_pack(&lapbeth_packet_type); 446 unregister_netdevice_notifier(&lapbeth_dev_notifier); 447 448 rtnl_lock(); 449 list_for_each_safe(entry, tmp, &lapbeth_devices) { 450 lapbeth = list_entry(entry, struct lapbethdev, node); 451 452 dev_put(lapbeth->ethdev); 453 unregister_netdevice(lapbeth->axdev); 454 } 455 rtnl_unlock(); 456 } 457 module_exit(lapbeth_cleanup_driver); 458 459 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 460 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 461 MODULE_LICENSE("GPL"); 462