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 skb_push(skb, 1); 132 133 if (skb_cow(skb, 1)) 134 return NET_RX_DROP; 135 136 ptr = skb->data; 137 *ptr = X25_IFACE_DATA; 138 139 skb->protocol = x25_type_trans(skb, dev); 140 return netif_rx(skb); 141 } 142 143 /* 144 * Send a LAPB frame via an ethernet interface 145 */ 146 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, 147 struct net_device *dev) 148 { 149 int err; 150 151 /* 152 * Just to be *really* sure not to send anything if the interface 153 * is down, the ethernet device may have gone. 154 */ 155 if (!netif_running(dev)) 156 goto drop; 157 158 switch (skb->data[0]) { 159 case X25_IFACE_DATA: 160 break; 161 case X25_IFACE_CONNECT: 162 if ((err = lapb_connect_request(dev)) != LAPB_OK) 163 pr_err("lapb_connect_request error: %d\n", err); 164 goto drop; 165 case X25_IFACE_DISCONNECT: 166 if ((err = lapb_disconnect_request(dev)) != LAPB_OK) 167 pr_err("lapb_disconnect_request err: %d\n", err); 168 /* Fall thru */ 169 default: 170 goto drop; 171 } 172 173 skb_pull(skb, 1); 174 175 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) { 176 pr_err("lapb_data_request error - %d\n", err); 177 goto drop; 178 } 179 out: 180 return NETDEV_TX_OK; 181 drop: 182 kfree_skb(skb); 183 goto out; 184 } 185 186 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb) 187 { 188 struct lapbethdev *lapbeth = netdev_priv(ndev); 189 unsigned char *ptr; 190 struct net_device *dev; 191 int size = skb->len; 192 193 skb->protocol = htons(ETH_P_X25); 194 195 ptr = skb_push(skb, 2); 196 197 *ptr++ = size % 256; 198 *ptr++ = size / 256; 199 200 ndev->stats.tx_packets++; 201 ndev->stats.tx_bytes += size; 202 203 skb->dev = dev = lapbeth->ethdev; 204 205 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0); 206 207 dev_queue_xmit(skb); 208 } 209 210 static void lapbeth_connected(struct net_device *dev, int reason) 211 { 212 unsigned char *ptr; 213 struct sk_buff *skb = dev_alloc_skb(1); 214 215 if (!skb) { 216 pr_err("out of memory\n"); 217 return; 218 } 219 220 ptr = skb_put(skb, 1); 221 *ptr = X25_IFACE_CONNECT; 222 223 skb->protocol = x25_type_trans(skb, dev); 224 netif_rx(skb); 225 } 226 227 static void lapbeth_disconnected(struct net_device *dev, int reason) 228 { 229 unsigned char *ptr; 230 struct sk_buff *skb = dev_alloc_skb(1); 231 232 if (!skb) { 233 pr_err("out of memory\n"); 234 return; 235 } 236 237 ptr = skb_put(skb, 1); 238 *ptr = X25_IFACE_DISCONNECT; 239 240 skb->protocol = x25_type_trans(skb, dev); 241 netif_rx(skb); 242 } 243 244 /* 245 * Set AX.25 callsign 246 */ 247 static int lapbeth_set_mac_address(struct net_device *dev, void *addr) 248 { 249 struct sockaddr *sa = addr; 250 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 251 return 0; 252 } 253 254 255 static const struct lapb_register_struct lapbeth_callbacks = { 256 .connect_confirmation = lapbeth_connected, 257 .connect_indication = lapbeth_connected, 258 .disconnect_confirmation = lapbeth_disconnected, 259 .disconnect_indication = lapbeth_disconnected, 260 .data_indication = lapbeth_data_indication, 261 .data_transmit = lapbeth_data_transmit, 262 }; 263 264 /* 265 * open/close a device 266 */ 267 static int lapbeth_open(struct net_device *dev) 268 { 269 int err; 270 271 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { 272 pr_err("lapb_register error: %d\n", err); 273 return -ENODEV; 274 } 275 276 netif_start_queue(dev); 277 return 0; 278 } 279 280 static int lapbeth_close(struct net_device *dev) 281 { 282 int err; 283 284 netif_stop_queue(dev); 285 286 if ((err = lapb_unregister(dev)) != LAPB_OK) 287 pr_err("lapb_unregister error: %d\n", err); 288 289 return 0; 290 } 291 292 /* ------------------------------------------------------------------------ */ 293 294 static const struct net_device_ops lapbeth_netdev_ops = { 295 .ndo_open = lapbeth_open, 296 .ndo_stop = lapbeth_close, 297 .ndo_start_xmit = lapbeth_xmit, 298 .ndo_set_mac_address = lapbeth_set_mac_address, 299 }; 300 301 static void lapbeth_setup(struct net_device *dev) 302 { 303 dev->netdev_ops = &lapbeth_netdev_ops; 304 dev->needs_free_netdev = true; 305 dev->type = ARPHRD_X25; 306 dev->hard_header_len = 3; 307 dev->mtu = 1000; 308 dev->addr_len = 0; 309 } 310 311 /* 312 * Setup a new device. 313 */ 314 static int lapbeth_new_device(struct net_device *dev) 315 { 316 struct net_device *ndev; 317 struct lapbethdev *lapbeth; 318 int rc = -ENOMEM; 319 320 ASSERT_RTNL(); 321 322 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN, 323 lapbeth_setup); 324 if (!ndev) 325 goto out; 326 327 lapbeth = netdev_priv(ndev); 328 lapbeth->axdev = ndev; 329 330 dev_hold(dev); 331 lapbeth->ethdev = dev; 332 333 rc = -EIO; 334 if (register_netdevice(ndev)) 335 goto fail; 336 337 list_add_rcu(&lapbeth->node, &lapbeth_devices); 338 rc = 0; 339 out: 340 return rc; 341 fail: 342 dev_put(dev); 343 free_netdev(ndev); 344 goto out; 345 } 346 347 /* 348 * Free a lapb network device. 349 */ 350 static void lapbeth_free_device(struct lapbethdev *lapbeth) 351 { 352 dev_put(lapbeth->ethdev); 353 list_del_rcu(&lapbeth->node); 354 unregister_netdevice(lapbeth->axdev); 355 } 356 357 /* 358 * Handle device status changes. 359 * 360 * Called from notifier with RTNL held. 361 */ 362 static int lapbeth_device_event(struct notifier_block *this, 363 unsigned long event, void *ptr) 364 { 365 struct lapbethdev *lapbeth; 366 struct net_device *dev = netdev_notifier_info_to_dev(ptr); 367 368 if (dev_net(dev) != &init_net) 369 return NOTIFY_DONE; 370 371 if (!dev_is_ethdev(dev)) 372 return NOTIFY_DONE; 373 374 switch (event) { 375 case NETDEV_UP: 376 /* New ethernet device -> new LAPB interface */ 377 if (lapbeth_get_x25_dev(dev) == NULL) 378 lapbeth_new_device(dev); 379 break; 380 case NETDEV_DOWN: 381 /* ethernet device closed -> close LAPB interface */ 382 lapbeth = lapbeth_get_x25_dev(dev); 383 if (lapbeth) 384 dev_close(lapbeth->axdev); 385 break; 386 case NETDEV_UNREGISTER: 387 /* ethernet device disappears -> remove LAPB interface */ 388 lapbeth = lapbeth_get_x25_dev(dev); 389 if (lapbeth) 390 lapbeth_free_device(lapbeth); 391 break; 392 } 393 394 return NOTIFY_DONE; 395 } 396 397 /* ------------------------------------------------------------------------ */ 398 399 static struct packet_type lapbeth_packet_type __read_mostly = { 400 .type = cpu_to_be16(ETH_P_DEC), 401 .func = lapbeth_rcv, 402 }; 403 404 static struct notifier_block lapbeth_dev_notifier = { 405 .notifier_call = lapbeth_device_event, 406 }; 407 408 static const char banner[] __initconst = 409 KERN_INFO "LAPB Ethernet driver version 0.02\n"; 410 411 static int __init lapbeth_init_driver(void) 412 { 413 dev_add_pack(&lapbeth_packet_type); 414 415 register_netdevice_notifier(&lapbeth_dev_notifier); 416 417 printk(banner); 418 419 return 0; 420 } 421 module_init(lapbeth_init_driver); 422 423 static void __exit lapbeth_cleanup_driver(void) 424 { 425 struct lapbethdev *lapbeth; 426 struct list_head *entry, *tmp; 427 428 dev_remove_pack(&lapbeth_packet_type); 429 unregister_netdevice_notifier(&lapbeth_dev_notifier); 430 431 rtnl_lock(); 432 list_for_each_safe(entry, tmp, &lapbeth_devices) { 433 lapbeth = list_entry(entry, struct lapbethdev, node); 434 435 dev_put(lapbeth->ethdev); 436 unregister_netdevice(lapbeth->axdev); 437 } 438 rtnl_unlock(); 439 } 440 module_exit(lapbeth_cleanup_driver); 441 442 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>"); 443 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); 444 MODULE_LICENSE("GPL"); 445