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.
49 #define MAXLAPBDEV 100
52 struct list_head node;
53 struct net_device *ethdev; /* link to ethernet device */
54 struct net_device *axdev; /* lapbeth device (lapb#) */
56 spinlock_t up_lock; /* Protects "up" */
57 struct sk_buff_head rx_queue;
58 struct napi_struct napi;
61 static LIST_HEAD(lapbeth_devices);
63 static void lapbeth_connected(struct net_device *dev, int reason);
64 static void lapbeth_disconnected(struct net_device *dev, int reason);
66 /* ------------------------------------------------------------------------ */
68 /* Get the LAPB device for the ethernet device
70 static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
72 struct lapbethdev *lapbeth;
74 list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
75 if (lapbeth->ethdev == dev)
81 static __inline__ int dev_is_ethdev(struct net_device *dev)
83 return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
86 /* ------------------------------------------------------------------------ */
88 static int lapbeth_napi_poll(struct napi_struct *napi, int budget)
90 struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev,
95 for (; processed < budget; ++processed) {
96 skb = skb_dequeue(&lapbeth->rx_queue);
99 netif_receive_skb_core(skb);
102 if (processed < budget)
108 /* Receive a LAPB frame via an ethernet interface.
110 static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev,
111 struct packet_type *ptype, struct net_device *orig_dev)
114 struct lapbethdev *lapbeth;
116 if (dev_net(dev) != &init_net)
119 skb = skb_share_check(skb, GFP_ATOMIC);
123 if (!pskb_may_pull(skb, 2))
127 lapbeth = lapbeth_get_x25_dev(dev);
129 goto drop_unlock_rcu;
130 spin_lock_bh(&lapbeth->up_lock);
134 len = skb->data[0] + skb->data[1] * 256;
135 dev->stats.rx_packets++;
136 dev->stats.rx_bytes += len;
138 skb_pull(skb, 2); /* Remove the length bytes */
139 skb_trim(skb, len); /* Set the length of the data */
141 err = lapb_data_received(lapbeth->axdev, skb);
142 if (err != LAPB_OK) {
143 printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
147 spin_unlock_bh(&lapbeth->up_lock);
160 static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
162 struct lapbethdev *lapbeth = netdev_priv(dev);
165 if (skb_cow(skb, 1)) {
173 *ptr = X25_IFACE_DATA;
175 skb->protocol = x25_type_trans(skb, dev);
177 skb_queue_tail(&lapbeth->rx_queue, skb);
178 napi_schedule(&lapbeth->napi);
179 return NET_RX_SUCCESS;
182 /* Send a LAPB frame via an ethernet interface
184 static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
185 struct net_device *dev)
187 struct lapbethdev *lapbeth = netdev_priv(dev);
190 spin_lock_bh(&lapbeth->up_lock);
194 /* There should be a pseudo header of 1 byte added by upper layers.
195 * Check to make sure it is there before reading it.
200 switch (skb->data[0]) {
203 case X25_IFACE_CONNECT:
204 err = lapb_connect_request(dev);
205 if (err == LAPB_CONNECTED)
206 lapbeth_connected(dev, LAPB_OK);
207 else if (err != LAPB_OK)
208 pr_err("lapb_connect_request error: %d\n", err);
210 case X25_IFACE_DISCONNECT:
211 err = lapb_disconnect_request(dev);
212 if (err == LAPB_NOTCONNECTED)
213 lapbeth_disconnected(dev, LAPB_OK);
214 else if (err != LAPB_OK)
215 pr_err("lapb_disconnect_request err: %d\n", err);
223 err = lapb_data_request(dev, skb);
224 if (err != LAPB_OK) {
225 pr_err("lapb_data_request error - %d\n", err);
229 spin_unlock_bh(&lapbeth->up_lock);
236 static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
238 struct lapbethdev *lapbeth = netdev_priv(ndev);
240 struct net_device *dev;
243 ptr = skb_push(skb, 2);
248 ndev->stats.tx_packets++;
249 ndev->stats.tx_bytes += size;
251 skb->dev = dev = lapbeth->ethdev;
253 skb->protocol = htons(ETH_P_DEC);
255 skb_reset_network_header(skb);
257 dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
262 static void lapbeth_connected(struct net_device *dev, int reason)
264 struct lapbethdev *lapbeth = netdev_priv(dev);
266 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
271 ptr = skb_put(skb, 1);
272 *ptr = X25_IFACE_CONNECT;
274 skb->protocol = x25_type_trans(skb, dev);
276 skb_queue_tail(&lapbeth->rx_queue, skb);
277 napi_schedule(&lapbeth->napi);
280 static void lapbeth_disconnected(struct net_device *dev, int reason)
282 struct lapbethdev *lapbeth = netdev_priv(dev);
284 struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
289 ptr = skb_put(skb, 1);
290 *ptr = X25_IFACE_DISCONNECT;
292 skb->protocol = x25_type_trans(skb, dev);
294 skb_queue_tail(&lapbeth->rx_queue, skb);
295 napi_schedule(&lapbeth->napi);
298 /* Set AX.25 callsign
300 static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
302 struct sockaddr *sa = addr;
304 dev_addr_set(dev, sa->sa_data);
308 static const struct lapb_register_struct lapbeth_callbacks = {
309 .connect_confirmation = lapbeth_connected,
310 .connect_indication = lapbeth_connected,
311 .disconnect_confirmation = lapbeth_disconnected,
312 .disconnect_indication = lapbeth_disconnected,
313 .data_indication = lapbeth_data_indication,
314 .data_transmit = lapbeth_data_transmit,
317 /* open/close a device
319 static int lapbeth_open(struct net_device *dev)
321 struct lapbethdev *lapbeth = netdev_priv(dev);
324 napi_enable(&lapbeth->napi);
326 err = lapb_register(dev, &lapbeth_callbacks);
327 if (err != LAPB_OK) {
328 pr_err("lapb_register error: %d\n", err);
332 spin_lock_bh(&lapbeth->up_lock);
334 spin_unlock_bh(&lapbeth->up_lock);
339 static int lapbeth_close(struct net_device *dev)
341 struct lapbethdev *lapbeth = netdev_priv(dev);
344 spin_lock_bh(&lapbeth->up_lock);
346 spin_unlock_bh(&lapbeth->up_lock);
348 err = lapb_unregister(dev);
350 pr_err("lapb_unregister error: %d\n", err);
352 napi_disable(&lapbeth->napi);
357 /* ------------------------------------------------------------------------ */
359 static const struct net_device_ops lapbeth_netdev_ops = {
360 .ndo_open = lapbeth_open,
361 .ndo_stop = lapbeth_close,
362 .ndo_start_xmit = lapbeth_xmit,
363 .ndo_set_mac_address = lapbeth_set_mac_address,
366 static void lapbeth_setup(struct net_device *dev)
368 dev->netdev_ops = &lapbeth_netdev_ops;
369 dev->needs_free_netdev = true;
370 dev->type = ARPHRD_X25;
371 dev->hard_header_len = 0;
376 /* Setup a new device.
378 static int lapbeth_new_device(struct net_device *dev)
380 struct net_device *ndev;
381 struct lapbethdev *lapbeth;
386 ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
391 /* When transmitting data:
392 * first this driver removes a pseudo header of 1 byte,
393 * then the lapb module prepends an LAPB header of at most 3 bytes,
394 * then this driver prepends a length field of 2 bytes,
395 * then the underlying Ethernet device prepends its own header.
397 ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
398 + dev->needed_headroom;
399 ndev->needed_tailroom = dev->needed_tailroom;
401 lapbeth = netdev_priv(ndev);
402 lapbeth->axdev = ndev;
405 lapbeth->ethdev = dev;
408 spin_lock_init(&lapbeth->up_lock);
410 skb_queue_head_init(&lapbeth->rx_queue);
411 netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
414 if (register_netdevice(ndev))
417 list_add_rcu(&lapbeth->node, &lapbeth_devices);
427 /* Free a lapb network device.
429 static void lapbeth_free_device(struct lapbethdev *lapbeth)
431 dev_put(lapbeth->ethdev);
432 list_del_rcu(&lapbeth->node);
433 unregister_netdevice(lapbeth->axdev);
436 /* Handle device status changes.
438 * Called from notifier with RTNL held.
440 static int lapbeth_device_event(struct notifier_block *this,
441 unsigned long event, void *ptr)
443 struct lapbethdev *lapbeth;
444 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
446 if (dev_net(dev) != &init_net)
449 if (!dev_is_ethdev(dev))
454 /* New ethernet device -> new LAPB interface */
455 if (!lapbeth_get_x25_dev(dev))
456 lapbeth_new_device(dev);
458 case NETDEV_GOING_DOWN:
459 /* ethernet device closes -> close LAPB interface */
460 lapbeth = lapbeth_get_x25_dev(dev);
462 dev_close(lapbeth->axdev);
464 case NETDEV_UNREGISTER:
465 /* ethernet device disappears -> remove LAPB interface */
466 lapbeth = lapbeth_get_x25_dev(dev);
468 lapbeth_free_device(lapbeth);
475 /* ------------------------------------------------------------------------ */
477 static struct packet_type lapbeth_packet_type __read_mostly = {
478 .type = cpu_to_be16(ETH_P_DEC),
482 static struct notifier_block lapbeth_dev_notifier = {
483 .notifier_call = lapbeth_device_event,
486 static const char banner[] __initconst =
487 KERN_INFO "LAPB Ethernet driver version 0.02\n";
489 static int __init lapbeth_init_driver(void)
491 dev_add_pack(&lapbeth_packet_type);
493 register_netdevice_notifier(&lapbeth_dev_notifier);
499 module_init(lapbeth_init_driver);
501 static void __exit lapbeth_cleanup_driver(void)
503 struct lapbethdev *lapbeth;
504 struct list_head *entry, *tmp;
506 dev_remove_pack(&lapbeth_packet_type);
507 unregister_netdevice_notifier(&lapbeth_dev_notifier);
510 list_for_each_safe(entry, tmp, &lapbeth_devices) {
511 lapbeth = list_entry(entry, struct lapbethdev, node);
513 dev_put(lapbeth->ethdev);
514 unregister_netdevice(lapbeth->axdev);
518 module_exit(lapbeth_cleanup_driver);
520 MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
521 MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
522 MODULE_LICENSE("GPL");