1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Generic HDLC support routines for Linux
4 *
5 * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
6 *
7 * Currently supported:
8 * * raw IP-in-HDLC
9 * * Cisco HDLC
10 * * Frame Relay with ANSI or CCITT LMI (both user and network side)
11 * * PPP
12 * * X.25
13 *
14 * Use sethdlc utility to set line parameters, protocol and PVCs
15 *
16 * How does it work:
17 * - proto->open(), close(), start(), stop() calls are serialized.
18 * The order is: open, [ start, stop ... ] close ...
19 * - proto->start() and stop() are called with spin_lock_irq held.
20 */
21
22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24 #include <linux/errno.h>
25 #include <linux/hdlc.h>
26 #include <linux/if_arp.h>
27 #include <linux/inetdevice.h>
28 #include <linux/init.h>
29 #include <linux/kernel.h>
30 #include <linux/module.h>
31 #include <linux/notifier.h>
32 #include <linux/pkt_sched.h>
33 #include <linux/poll.h>
34 #include <linux/rtnetlink.h>
35 #include <linux/skbuff.h>
36 #include <linux/slab.h>
37 #include <net/net_namespace.h>
38
39
40 static const char* version = "HDLC support module revision 1.22";
41
42 #undef DEBUG_LINK
43
44 static struct hdlc_proto *first_proto;
45
hdlc_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * p,struct net_device * orig_dev)46 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
47 struct packet_type *p, struct net_device *orig_dev)
48 {
49 struct hdlc_device *hdlc = dev_to_hdlc(dev);
50
51 if (!net_eq(dev_net(dev), &init_net)) {
52 kfree_skb(skb);
53 return 0;
54 }
55
56 BUG_ON(!hdlc->proto->netif_rx);
57 return hdlc->proto->netif_rx(skb);
58 }
59
hdlc_start_xmit(struct sk_buff * skb,struct net_device * dev)60 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
61 {
62 hdlc_device *hdlc = dev_to_hdlc(dev);
63
64 if (hdlc->proto->xmit)
65 return hdlc->proto->xmit(skb, dev);
66
67 return hdlc->xmit(skb, dev); /* call hardware driver directly */
68 }
69
hdlc_proto_start(struct net_device * dev)70 static inline void hdlc_proto_start(struct net_device *dev)
71 {
72 hdlc_device *hdlc = dev_to_hdlc(dev);
73 if (hdlc->proto->start)
74 hdlc->proto->start(dev);
75 }
76
77
78
hdlc_proto_stop(struct net_device * dev)79 static inline void hdlc_proto_stop(struct net_device *dev)
80 {
81 hdlc_device *hdlc = dev_to_hdlc(dev);
82 if (hdlc->proto->stop)
83 hdlc->proto->stop(dev);
84 }
85
86
87
hdlc_device_event(struct notifier_block * this,unsigned long event,void * ptr)88 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
89 void *ptr)
90 {
91 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
92 hdlc_device *hdlc;
93 unsigned long flags;
94 int on;
95
96 if (!net_eq(dev_net(dev), &init_net))
97 return NOTIFY_DONE;
98
99 if (!(dev->priv_flags & IFF_WAN_HDLC))
100 return NOTIFY_DONE; /* not an HDLC device */
101
102 if (event != NETDEV_CHANGE)
103 return NOTIFY_DONE; /* Only interested in carrier changes */
104
105 on = netif_carrier_ok(dev);
106
107 #ifdef DEBUG_LINK
108 printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
109 dev->name, on);
110 #endif
111
112 hdlc = dev_to_hdlc(dev);
113 spin_lock_irqsave(&hdlc->state_lock, flags);
114
115 if (hdlc->carrier == on)
116 goto carrier_exit; /* no change in DCD line level */
117
118 hdlc->carrier = on;
119
120 if (!hdlc->open)
121 goto carrier_exit;
122
123 if (hdlc->carrier) {
124 netdev_info(dev, "Carrier detected\n");
125 hdlc_proto_start(dev);
126 } else {
127 netdev_info(dev, "Carrier lost\n");
128 hdlc_proto_stop(dev);
129 }
130
131 carrier_exit:
132 spin_unlock_irqrestore(&hdlc->state_lock, flags);
133 return NOTIFY_DONE;
134 }
135
136
137
138 /* Must be called by hardware driver when HDLC device is being opened */
hdlc_open(struct net_device * dev)139 int hdlc_open(struct net_device *dev)
140 {
141 hdlc_device *hdlc = dev_to_hdlc(dev);
142 #ifdef DEBUG_LINK
143 printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
144 hdlc->carrier, hdlc->open);
145 #endif
146
147 if (hdlc->proto == NULL)
148 return -ENOSYS; /* no protocol attached */
149
150 if (hdlc->proto->open) {
151 int result = hdlc->proto->open(dev);
152 if (result)
153 return result;
154 }
155
156 spin_lock_irq(&hdlc->state_lock);
157
158 if (hdlc->carrier) {
159 netdev_info(dev, "Carrier detected\n");
160 hdlc_proto_start(dev);
161 } else
162 netdev_info(dev, "No carrier\n");
163
164 hdlc->open = 1;
165
166 spin_unlock_irq(&hdlc->state_lock);
167 return 0;
168 }
169
170
171
172 /* Must be called by hardware driver when HDLC device is being closed */
hdlc_close(struct net_device * dev)173 void hdlc_close(struct net_device *dev)
174 {
175 hdlc_device *hdlc = dev_to_hdlc(dev);
176 #ifdef DEBUG_LINK
177 printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
178 hdlc->carrier, hdlc->open);
179 #endif
180
181 spin_lock_irq(&hdlc->state_lock);
182
183 hdlc->open = 0;
184 if (hdlc->carrier)
185 hdlc_proto_stop(dev);
186
187 spin_unlock_irq(&hdlc->state_lock);
188
189 if (hdlc->proto->close)
190 hdlc->proto->close(dev);
191 }
192
193
194
hdlc_ioctl(struct net_device * dev,struct ifreq * ifr,int cmd)195 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
196 {
197 struct hdlc_proto *proto = first_proto;
198 int result;
199
200 if (cmd != SIOCWANDEV)
201 return -EINVAL;
202
203 if (dev_to_hdlc(dev)->proto) {
204 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
205 if (result != -EINVAL)
206 return result;
207 }
208
209 /* Not handled by currently attached protocol (if any) */
210
211 while (proto) {
212 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
213 return result;
214 proto = proto->next;
215 }
216 return -EINVAL;
217 }
218
219 static const struct header_ops hdlc_null_ops;
220
hdlc_setup_dev(struct net_device * dev)221 static void hdlc_setup_dev(struct net_device *dev)
222 {
223 /* Re-init all variables changed by HDLC protocol drivers,
224 * including ether_setup() called from hdlc_raw_eth.c.
225 */
226 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
227 dev->priv_flags = IFF_WAN_HDLC;
228 dev->mtu = HDLC_MAX_MTU;
229 dev->min_mtu = 68;
230 dev->max_mtu = HDLC_MAX_MTU;
231 dev->type = ARPHRD_RAWHDLC;
232 dev->hard_header_len = 16;
233 dev->addr_len = 0;
234 dev->header_ops = &hdlc_null_ops;
235 }
236
hdlc_setup(struct net_device * dev)237 static void hdlc_setup(struct net_device *dev)
238 {
239 hdlc_device *hdlc = dev_to_hdlc(dev);
240
241 hdlc_setup_dev(dev);
242 hdlc->carrier = 1;
243 hdlc->open = 0;
244 spin_lock_init(&hdlc->state_lock);
245 }
246
alloc_hdlcdev(void * priv)247 struct net_device *alloc_hdlcdev(void *priv)
248 {
249 struct net_device *dev;
250 dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
251 NET_NAME_UNKNOWN, hdlc_setup);
252 if (dev)
253 dev_to_hdlc(dev)->priv = priv;
254 return dev;
255 }
256
unregister_hdlc_device(struct net_device * dev)257 void unregister_hdlc_device(struct net_device *dev)
258 {
259 rtnl_lock();
260 detach_hdlc_protocol(dev);
261 unregister_netdevice(dev);
262 rtnl_unlock();
263 }
264
265
266
attach_hdlc_protocol(struct net_device * dev,struct hdlc_proto * proto,size_t size)267 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
268 size_t size)
269 {
270 int err;
271
272 err = detach_hdlc_protocol(dev);
273 if (err)
274 return err;
275
276 if (!try_module_get(proto->module))
277 return -ENOSYS;
278
279 if (size) {
280 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
281 if (dev_to_hdlc(dev)->state == NULL) {
282 module_put(proto->module);
283 return -ENOBUFS;
284 }
285 }
286 dev_to_hdlc(dev)->proto = proto;
287
288 return 0;
289 }
290
291
detach_hdlc_protocol(struct net_device * dev)292 int detach_hdlc_protocol(struct net_device *dev)
293 {
294 hdlc_device *hdlc = dev_to_hdlc(dev);
295 int err;
296
297 if (hdlc->proto) {
298 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
299 err = notifier_to_errno(err);
300 if (err) {
301 netdev_err(dev, "Refused to change device type\n");
302 return err;
303 }
304
305 if (hdlc->proto->detach)
306 hdlc->proto->detach(dev);
307 module_put(hdlc->proto->module);
308 hdlc->proto = NULL;
309 }
310 kfree(hdlc->state);
311 hdlc->state = NULL;
312 hdlc_setup_dev(dev);
313
314 return 0;
315 }
316
317
register_hdlc_protocol(struct hdlc_proto * proto)318 void register_hdlc_protocol(struct hdlc_proto *proto)
319 {
320 rtnl_lock();
321 proto->next = first_proto;
322 first_proto = proto;
323 rtnl_unlock();
324 }
325
326
unregister_hdlc_protocol(struct hdlc_proto * proto)327 void unregister_hdlc_protocol(struct hdlc_proto *proto)
328 {
329 struct hdlc_proto **p;
330
331 rtnl_lock();
332 p = &first_proto;
333 while (*p != proto) {
334 BUG_ON(!*p);
335 p = &((*p)->next);
336 }
337 *p = proto->next;
338 rtnl_unlock();
339 }
340
341
342
343 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
344 MODULE_DESCRIPTION("HDLC support module");
345 MODULE_LICENSE("GPL v2");
346
347 EXPORT_SYMBOL(hdlc_start_xmit);
348 EXPORT_SYMBOL(hdlc_open);
349 EXPORT_SYMBOL(hdlc_close);
350 EXPORT_SYMBOL(hdlc_ioctl);
351 EXPORT_SYMBOL(alloc_hdlcdev);
352 EXPORT_SYMBOL(unregister_hdlc_device);
353 EXPORT_SYMBOL(register_hdlc_protocol);
354 EXPORT_SYMBOL(unregister_hdlc_protocol);
355 EXPORT_SYMBOL(attach_hdlc_protocol);
356 EXPORT_SYMBOL(detach_hdlc_protocol);
357
358 static struct packet_type hdlc_packet_type __read_mostly = {
359 .type = cpu_to_be16(ETH_P_HDLC),
360 .func = hdlc_rcv,
361 };
362
363
364 static struct notifier_block hdlc_notifier = {
365 .notifier_call = hdlc_device_event,
366 };
367
368
hdlc_module_init(void)369 static int __init hdlc_module_init(void)
370 {
371 int result;
372
373 pr_info("%s\n", version);
374 if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
375 return result;
376 dev_add_pack(&hdlc_packet_type);
377 return 0;
378 }
379
380
381
hdlc_module_exit(void)382 static void __exit hdlc_module_exit(void)
383 {
384 dev_remove_pack(&hdlc_packet_type);
385 unregister_netdevice_notifier(&hdlc_notifier);
386 }
387
388
389 module_init(hdlc_module_init);
390 module_exit(hdlc_module_exit);
391
