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 switch (skb->data[0]) { 161 case X25_IFACE_DATA: 162 break; 163 case X25_IFACE_CONNECT: 164 if ((err = lapb_connect_request(dev)) != LAPB_OK) 165 pr_err("lapb_connect_request error: %d\n", err); 166 goto drop; 167 case X25_IFACE_DISCONNECT: 168 if ((err = lapb_disconnect_request(dev)) != LAPB_OK) 169 pr_err("lapb_disconnect_request err: %d\n", err); 170 /* Fall thru */ 171 default: 172 goto drop; 173 } 174 175 skb_pull(skb, 1); 176 177 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) { 178 pr_err("lapb_data_request error - %d\n", err); 179 goto drop; 180 } 181 out: 182 return NETDEV_TX_OK; 183 drop: 184 kfree_skb(skb); 185 goto out; 186 } 187 188 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 189 { 190 struct lapbethdev *lapbeth = netdev_priv(ndev); 191 unsigned char *ptr; 192 struct net_device *dev; 193 int size = skb->len; 194 195 skb->protocol = htons(ETH_P_X25); 196 197 ptr = skb_push(skb, 2); 198 199 *ptr++ = size % 256; 200 *ptr++ = size / 256; 201 202 ndev->stats.tx_packets++; 203 ndev->stats.tx_bytes += size; 204 205 skb->dev = dev = lapbeth->ethdev; 206 207 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 208 209 dev_queue_xmit(skb); 210 } 211 212 static void lapbeth_connected(struct net_device *dev, int reason) 213 { 214 unsigned char *ptr; 215 struct sk_buff *skb = dev_alloc_skb(1); 216 217 if (!skb) { 218 pr_err("out of memory\n"); 219 return; 220 } 221 222 ptr = skb_put(skb, 1); 223 *ptr = X25_IFACE_CONNECT; 224 225 skb->protocol = x25_type_trans(skb, dev); 226 netif_rx(skb); 227 } 228 229 static void lapbeth_disconnected(struct net_device *dev, int reason) 230 { 231 unsigned char *ptr; 232 struct sk_buff *skb = dev_alloc_skb(1); 233 234 if (!skb) { 235 pr_err("out of memory\n"); 236 return; 237 } 238 239 ptr = skb_put(skb, 1); 240 *ptr = X25_IFACE_DISCONNECT; 241 242 skb->protocol = x25_type_trans(skb, dev); 243 netif_rx(skb); 244 } 245 246 /* 247 * Set AX.25 callsign 248 */ 249 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 250 { 251 struct sockaddr *sa = addr; 252 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 253 return 0; 254 } 255 256 257 static const struct lapb_register_struct lapbeth_callbacks = { 258 .connect_confirmation = lapbeth_connected, 259 .connect_indication = lapbeth_connected, 260 .disconnect_confirmation = lapbeth_disconnected, 261 .disconnect_indication = lapbeth_disconnected, 262 .data_indication = lapbeth_data_indication, 263 .data_transmit = lapbeth_data_transmit, 264 }; 265 266 /* 267 * open/close a device 268 */ 269 static int lapbeth_open(struct net_device *dev) 270 { 271 int err; 272 273 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 274 pr_err("lapb_register error: %d\n", err); 275 return -ENODEV; 276 } 277 278 netif_start_queue(dev); 279 return 0; 280 } 281 282 static int lapbeth_close(struct net_device *dev) 283 { 284 int err; 285 286 netif_stop_queue(dev); 287 288 if ((err = lapb_unregister(dev)) != LAPB_OK) 289 pr_err("lapb_unregister error: %d\n", err); 290 291 return 0; 292 } 293 294 /* ------------------------------------------------------------------------ */ 295 296 static const struct net_device_ops lapbeth_netdev_ops = { 297 .ndo_open = lapbeth_open, 298 .ndo_stop = lapbeth_close, 299 .ndo_start_xmit = lapbeth_xmit, 300 .ndo_set_mac_address = lapbeth_set_mac_address, 301 }; 302 303 static void lapbeth_setup(struct net_device *dev) 304 { 305 dev->netdev_ops = &lapbeth_netdev_ops; 306 dev->needs_free_netdev = true; 307 dev->type = ARPHRD_X25; 308 dev->mtu = 1000; 309 dev->addr_len = 0; 310 } 311 312 /* 313 * Setup a new device. 314 */ 315 static int lapbeth_new_device(struct net_device *dev) 316 { 317 struct net_device *ndev; 318 struct lapbethdev *lapbeth; 319 int rc = -ENOMEM; 320 321 ASSERT_RTNL(); 322 323 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 324 lapbeth_setup); 325 if (!ndev) 326 goto out; 327 328 /* When transmitting data: 329 * first this driver removes a pseudo header of 1 byte, 330 * then the lapb module prepends an LAPB header of at most 3 bytes, 331 * then this driver prepends a length field of 2 bytes, 332 * then the underlying Ethernet device prepends its own header. 333 */ 334 ndev->hard_header_len = -1 + 3 + 2 + dev->hard_header_len; 335 336 lapbeth = netdev_priv(ndev); 337 lapbeth->axdev = ndev; 338 339 dev_hold(dev); 340 lapbeth->ethdev = dev; 341 342 rc = -EIO; 343 if (register_netdevice(ndev)) 344 goto fail; 345 346 list_add_rcu(&lapbeth->node, &lapbeth_devices); 347 rc = 0; 348 out: 349 return rc; 350 fail: 351 dev_put(dev); 352 free_netdev(ndev); 353 goto out; 354 } 355 356 /* 357 * Free a lapb network device. 358 */ 359 static void lapbeth_free_device(struct lapbethdev *lapbeth) 360 { 361 dev_put(lapbeth->ethdev); 362 list_del_rcu(&lapbeth->node); 363 unregister_netdevice(lapbeth->axdev); 364 } 365 366 /* 367 * Handle device status changes. 368 * 369 * Called from notifier with RTNL held. 370 */ 371 static int lapbeth_device_event(struct notifier_block *this, 372 unsigned long event, void *ptr) 373 { 374 struct lapbethdev *lapbeth; 375 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 376 377 if (dev_net(dev) != &init_net) 378 return NOTIFY_DONE; 379 380 if (!dev_is_ethdev(dev)) 381 return NOTIFY_DONE; 382 383 switch (event) { 384 case NETDEV_UP: 385 /* New ethernet device -> new LAPB interface */ 386 if (lapbeth_get_x25_dev(dev) == NULL) 387 lapbeth_new_device(dev); 388 break; 389 case NETDEV_DOWN: 390 /* ethernet device closed -> close LAPB interface */ 391 lapbeth = lapbeth_get_x25_dev(dev); 392 if (lapbeth) 393 dev_close(lapbeth->axdev); 394 break; 395 case NETDEV_UNREGISTER: 396 /* ethernet device disappears -> remove LAPB interface */ 397 lapbeth = lapbeth_get_x25_dev(dev); 398 if (lapbeth) 399 lapbeth_free_device(lapbeth); 400 break; 401 } 402 403 return NOTIFY_DONE; 404 } 405 406 /* ------------------------------------------------------------------------ */ 407 408 static struct packet_type lapbeth_packet_type __read_mostly = { 409 .type = cpu_to_be16(ETH_P_DEC), 410 .func = lapbeth_rcv, 411 }; 412 413 static struct notifier_block lapbeth_dev_notifier = { 414 .notifier_call = lapbeth_device_event, 415 }; 416 417 static const char banner[] __initconst = 418 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 419 420 static int __init lapbeth_init_driver(void) 421 { 422 dev_add_pack(&lapbeth_packet_type); 423 424 register_netdevice_notifier(&lapbeth_dev_notifier); 425 426 printk(banner); 427 428 return 0; 429 } 430 module_init(lapbeth_init_driver); 431 432 static void __exit lapbeth_cleanup_driver(void) 433 { 434 struct lapbethdev *lapbeth; 435 struct list_head *entry, *tmp; 436 437 dev_remove_pack(&lapbeth_packet_type); 438 unregister_netdevice_notifier(&lapbeth_dev_notifier); 439 440 rtnl_lock(); 441 list_for_each_safe(entry, tmp, &lapbeth_devices) { 442 lapbeth = list_entry(entry, struct lapbethdev, node); 443 444 dev_put(lapbeth->ethdev); 445 unregister_netdevice(lapbeth->axdev); 446 } 447 rtnl_unlock(); 448 } 449 module_exit(lapbeth_cleanup_driver); 450 451 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 452 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 453 MODULE_LICENSE("GPL"); 454