1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * "LAPB via ethernet" driver release 001
5 * This code REQUIRES 2.1.15 or higher/ NET3.038
7 * This is a "pseudo" network driver to allow LAPB over Ethernet.
9 * This driver can use any ethernet destination address, and can be
10 * limited to accept frames from one dedicated ethernet card only.
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
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/errno.h>
21 #include <linux/types.h>
22 #include <linux/socket.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>
33 #include <linux/uaccess.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>
42 #include <net/x25device.h>
44 static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
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
51 struct list_head node;
52 struct net_device *ethdev; /* link to ethernet device */
53 struct net_device *axdev; /* lapbeth device (lapb#) */
55 spinlock_t up_lock; /* Protects "up" */
58 static LIST_HEAD(lapbeth_devices);
60 /* ------------------------------------------------------------------------ */
63 * Get the LAPB device for the ethernet device
65 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
67 struct lapbethdev *lapbeth;
69 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
70 if (lapbeth->ethdev == dev)
76 static __inline__ int dev_is_ethdev(struct net_device *dev)
78 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
81 /* ------------------------------------------------------------------------ */
84 * Receive a LAPB frame via an ethernet interface.
86 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *ptype, struct net_device *orig_dev)
89 struct lapbethdev *lapbeth;
91 if (dev_net(dev) != &init_net)
94 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
97 if (!pskb_may_pull(skb, 2))
101 lapbeth = lapbeth_get_x25_dev(dev);
103 goto drop_unlock_rcu;
104 spin_lock_bh(&lapbeth->up_lock);
108 len = skb->data[0] + skb->data[1] * 256;
109 dev->stats.rx_packets++;
110 dev->stats.rx_bytes += len;
112 skb_pull(skb, 2); /* Remove the length bytes */
113 skb_trim(skb, len); /* Set the length of the data */
115 if ((err = lapb_data_received(lapbeth->axdev, skb)) != LAPB_OK) {
116 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
120 spin_unlock_bh(&lapbeth->up_lock);
133 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
137 if (skb_cow(skb, 1)) {
145 *ptr = X25_IFACE_DATA;
147 skb->protocol = x25_type_trans(skb, dev);
148 return netif_rx(skb);
152 * Send a LAPB frame via an ethernet interface
154 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
155 struct net_device *dev)
157 struct lapbethdev *lapbeth = netdev_priv(dev);
160 spin_lock_bh(&lapbeth->up_lock);
164 /* There should be a pseudo header of 1 byte added by upper layers.
165 * Check to make sure it is there before reading it.
170 switch (skb->data[0]) {
173 case X25_IFACE_CONNECT:
174 if ((err = lapb_connect_request(dev)) != LAPB_OK)
175 pr_err("lapb_connect_request error: %d\n", err);
177 case X25_IFACE_DISCONNECT:
178 if ((err = lapb_disconnect_request(dev)) != LAPB_OK)
179 pr_err("lapb_disconnect_request err: %d\n", err);
187 if ((err = lapb_data_request(dev, skb)) != LAPB_OK) {
188 pr_err("lapb_data_request error - %d\n", err);
192 spin_unlock_bh(&lapbeth->up_lock);
199 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
201 struct lapbethdev *lapbeth = netdev_priv(ndev);
203 struct net_device *dev;
206 ptr = skb_push(skb, 2);
211 ndev->stats.tx_packets++;
212 ndev->stats.tx_bytes += size;
214 skb->dev = dev = lapbeth->ethdev;
216 skb->protocol = htons(ETH_P_DEC);
218 skb_reset_network_header(skb);
220 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
225 static void lapbeth_connected(struct net_device *dev, int reason)
228 struct sk_buff *skb = dev_alloc_skb(1);
231 pr_err("out of memory\n");
235 ptr = skb_put(skb, 1);
236 *ptr = X25_IFACE_CONNECT;
238 skb->protocol = x25_type_trans(skb, dev);
242 static void lapbeth_disconnected(struct net_device *dev, int reason)
245 struct sk_buff *skb = dev_alloc_skb(1);
248 pr_err("out of memory\n");
252 ptr = skb_put(skb, 1);
253 *ptr = X25_IFACE_DISCONNECT;
255 skb->protocol = x25_type_trans(skb, dev);
262 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
264 struct sockaddr *sa = addr;
265 memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
270 static const struct lapb_register_struct lapbeth_callbacks = {
271 .connect_confirmation = lapbeth_connected,
272 .connect_indication = lapbeth_connected,
273 .disconnect_confirmation = lapbeth_disconnected,
274 .disconnect_indication = lapbeth_disconnected,
275 .data_indication = lapbeth_data_indication,
276 .data_transmit = lapbeth_data_transmit,
280 * open/close a device
282 static int lapbeth_open(struct net_device *dev)
284 struct lapbethdev *lapbeth = netdev_priv(dev);
287 if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) {
288 pr_err("lapb_register error: %d\n", err);
292 spin_lock_bh(&lapbeth->up_lock);
294 spin_unlock_bh(&lapbeth->up_lock);
299 static int lapbeth_close(struct net_device *dev)
301 struct lapbethdev *lapbeth = netdev_priv(dev);
304 spin_lock_bh(&lapbeth->up_lock);
306 spin_unlock_bh(&lapbeth->up_lock);
308 if ((err = lapb_unregister(dev)) != LAPB_OK)
309 pr_err("lapb_unregister error: %d\n", err);
314 /* ------------------------------------------------------------------------ */
316 static const struct net_device_ops lapbeth_netdev_ops = {
317 .ndo_open = lapbeth_open,
318 .ndo_stop = lapbeth_close,
319 .ndo_start_xmit = lapbeth_xmit,
320 .ndo_set_mac_address = lapbeth_set_mac_address,
323 static void lapbeth_setup(struct net_device *dev)
325 dev->netdev_ops = &lapbeth_netdev_ops;
326 dev->needs_free_netdev = true;
327 dev->type = ARPHRD_X25;
328 dev->hard_header_len = 0;
334 * Setup a new device.
336 static int lapbeth_new_device(struct net_device *dev)
338 struct net_device *ndev;
339 struct lapbethdev *lapbeth;
344 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
349 /* When transmitting data:
350 * first this driver removes a pseudo header of 1 byte,
351 * then the lapb module prepends an LAPB header of at most 3 bytes,
352 * then this driver prepends a length field of 2 bytes,
353 * then the underlying Ethernet device prepends its own header.
355 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
356 + dev->needed_headroom;
357 ndev->needed_tailroom = dev->needed_tailroom;
359 lapbeth = netdev_priv(ndev);
360 lapbeth->axdev = ndev;
363 lapbeth->ethdev = dev;
366 spin_lock_init(&lapbeth->up_lock);
369 if (register_netdevice(ndev))
372 list_add_rcu(&lapbeth->node, &lapbeth_devices);
383 * Free a lapb network device.
385 static void lapbeth_free_device(struct lapbethdev *lapbeth)
387 dev_put(lapbeth->ethdev);
388 list_del_rcu(&lapbeth->node);
389 unregister_netdevice(lapbeth->axdev);
393 * Handle device status changes.
395 * Called from notifier with RTNL held.
397 static int lapbeth_device_event(struct notifier_block *this,
398 unsigned long event, void *ptr)
400 struct lapbethdev *lapbeth;
401 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
403 if (dev_net(dev) != &init_net)
406 if (!dev_is_ethdev(dev))
411 /* New ethernet device -> new LAPB interface */
412 if (lapbeth_get_x25_dev(dev) == NULL)
413 lapbeth_new_device(dev);
416 /* ethernet device closed -> close LAPB interface */
417 lapbeth = lapbeth_get_x25_dev(dev);
419 dev_close(lapbeth->axdev);
421 case NETDEV_UNREGISTER:
422 /* ethernet device disappears -> remove LAPB interface */
423 lapbeth = lapbeth_get_x25_dev(dev);
425 lapbeth_free_device(lapbeth);
432 /* ------------------------------------------------------------------------ */
434 static struct packet_type lapbeth_packet_type __read_mostly = {
435 .type = cpu_to_be16(ETH_P_DEC),
439 static struct notifier_block lapbeth_dev_notifier = {
440 .notifier_call = lapbeth_device_event,
443 static const char banner[] __initconst =
444 KERN_INFO "LAPB Ethernet driver version 0.02\n";
446 static int __init lapbeth_init_driver(void)
448 dev_add_pack(&lapbeth_packet_type);
450 register_netdevice_notifier(&lapbeth_dev_notifier);
456 module_init(lapbeth_init_driver);
458 static void __exit lapbeth_cleanup_driver(void)
460 struct lapbethdev *lapbeth;
461 struct list_head *entry, *tmp;
463 dev_remove_pack(&lapbeth_packet_type);
464 unregister_netdevice_notifier(&lapbeth_dev_notifier);
467 list_for_each_safe(entry, tmp, &lapbeth_devices) {
468 lapbeth = list_entry(entry, struct lapbethdev, node);
470 dev_put(lapbeth->ethdev);
471 unregister_netdevice(lapbeth->axdev);
475 module_exit(lapbeth_cleanup_driver);
477 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
478 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
479 MODULE_LICENSE("GPL");