1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic HDLC support routines for Linux
4 * X.25 support
5 *
6 * Copyright (C) 1999 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
7 */
8
9#include <linux/errno.h>
10#include <linux/gfp.h>
11#include <linux/hdlc.h>
12#include <linux/if_arp.h>
13#include <linux/inetdevice.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/lapb.h>
17#include <linux/module.h>
18#include <linux/pkt_sched.h>
19#include <linux/poll.h>
20#include <linux/rtnetlink.h>
21#include <linux/skbuff.h>
22#include <net/x25device.h>
23
24struct x25_state {
25	x25_hdlc_proto settings;
26	bool up;
27	spinlock_t up_lock; /* Protects "up" */
28};
29
30static int x25_ioctl(struct net_device *dev, struct ifreq *ifr);
31
32static struct x25_state *state(hdlc_device *hdlc)
33{
34	return hdlc->state;
35}
36
37/* These functions are callbacks called by LAPB layer */
38
39static void x25_connect_disconnect(struct net_device *dev, int reason, int code)
40{
41	struct sk_buff *skb;
42	unsigned char *ptr;
43
44	if ((skb = dev_alloc_skb(1)) == NULL) {
45		netdev_err(dev, "out of memory\n");
46		return;
47	}
48
49	ptr = skb_put(skb, 1);
50	*ptr = code;
51
52	skb->protocol = x25_type_trans(skb, dev);
53	netif_rx(skb);
54}
55
56
57
58static void x25_connected(struct net_device *dev, int reason)
59{
60	x25_connect_disconnect(dev, reason, X25_IFACE_CONNECT);
61}
62
63
64
65static void x25_disconnected(struct net_device *dev, int reason)
66{
67	x25_connect_disconnect(dev, reason, X25_IFACE_DISCONNECT);
68}
69
70
71
72static int x25_data_indication(struct net_device *dev, struct sk_buff *skb)
73{
74	unsigned char *ptr;
75
76	if (skb_cow(skb, 1)) {
77		kfree_skb(skb);
78		return NET_RX_DROP;
79	}
80
81	skb_push(skb, 1);
82	skb_reset_network_header(skb);
83
84	ptr  = skb->data;
85	*ptr = X25_IFACE_DATA;
86
87	skb->protocol = x25_type_trans(skb, dev);
88	return netif_rx(skb);
89}
90
91
92
93static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb)
94{
95	hdlc_device *hdlc = dev_to_hdlc(dev);
96
97	skb_reset_network_header(skb);
98	skb->protocol = hdlc_type_trans(skb, dev);
99
100	if (dev_nit_active(dev))
101		dev_queue_xmit_nit(skb, dev);
102
103	hdlc->xmit(skb, dev); /* Ignore return value :-( */
104}
105
106
107
108static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
109{
110	hdlc_device *hdlc = dev_to_hdlc(dev);
111	struct x25_state *x25st = state(hdlc);
112	int result;
113
114	/* There should be a pseudo header of 1 byte added by upper layers.
115	 * Check to make sure it is there before reading it.
116	 */
117	if (skb->len < 1) {
118		kfree_skb(skb);
119		return NETDEV_TX_OK;
120	}
121
122	spin_lock_bh(&x25st->up_lock);
123	if (!x25st->up) {
124		spin_unlock_bh(&x25st->up_lock);
125		kfree_skb(skb);
126		return NETDEV_TX_OK;
127	}
128
129	switch (skb->data[0]) {
130	case X25_IFACE_DATA:	/* Data to be transmitted */
131		skb_pull(skb, 1);
132		skb_reset_network_header(skb);
133		if ((result = lapb_data_request(dev, skb)) != LAPB_OK)
134			dev_kfree_skb(skb);
135		spin_unlock_bh(&x25st->up_lock);
136		return NETDEV_TX_OK;
137
138	case X25_IFACE_CONNECT:
139		if ((result = lapb_connect_request(dev))!= LAPB_OK) {
140			if (result == LAPB_CONNECTED)
141				/* Send connect confirm. msg to level 3 */
142				x25_connected(dev, 0);
143			else
144				netdev_err(dev, "LAPB connect request failed, error code = %i\n",
145					   result);
146		}
147		break;
148
149	case X25_IFACE_DISCONNECT:
150		if ((result = lapb_disconnect_request(dev)) != LAPB_OK) {
151			if (result == LAPB_NOTCONNECTED)
152				/* Send disconnect confirm. msg to level 3 */
153				x25_disconnected(dev, 0);
154			else
155				netdev_err(dev, "LAPB disconnect request failed, error code = %i\n",
156					   result);
157		}
158		break;
159
160	default:		/* to be defined */
161		break;
162	}
163
164	spin_unlock_bh(&x25st->up_lock);
165	dev_kfree_skb(skb);
166	return NETDEV_TX_OK;
167}
168
169
170
171static int x25_open(struct net_device *dev)
172{
173	static const struct lapb_register_struct cb = {
174		.connect_confirmation = x25_connected,
175		.connect_indication = x25_connected,
176		.disconnect_confirmation = x25_disconnected,
177		.disconnect_indication = x25_disconnected,
178		.data_indication = x25_data_indication,
179		.data_transmit = x25_data_transmit,
180	};
181	hdlc_device *hdlc = dev_to_hdlc(dev);
182	struct x25_state *x25st = state(hdlc);
183	struct lapb_parms_struct params;
184	int result;
185
186	result = lapb_register(dev, &cb);
187	if (result != LAPB_OK)
188		return -ENOMEM;
189
190	result = lapb_getparms(dev, &params);
191	if (result != LAPB_OK)
192		return -EINVAL;
193
194	if (state(hdlc)->settings.dce)
195		params.mode = params.mode | LAPB_DCE;
196
197	if (state(hdlc)->settings.modulo == 128)
198		params.mode = params.mode | LAPB_EXTENDED;
199
200	params.window = state(hdlc)->settings.window;
201	params.t1 = state(hdlc)->settings.t1;
202	params.t2 = state(hdlc)->settings.t2;
203	params.n2 = state(hdlc)->settings.n2;
204
205	result = lapb_setparms(dev, &params);
206	if (result != LAPB_OK)
207		return -EINVAL;
208
209	spin_lock_bh(&x25st->up_lock);
210	x25st->up = true;
211	spin_unlock_bh(&x25st->up_lock);
212
213	return 0;
214}
215
216
217
218static void x25_close(struct net_device *dev)
219{
220	hdlc_device *hdlc = dev_to_hdlc(dev);
221	struct x25_state *x25st = state(hdlc);
222
223	spin_lock_bh(&x25st->up_lock);
224	x25st->up = false;
225	spin_unlock_bh(&x25st->up_lock);
226
227	lapb_unregister(dev);
228}
229
230
231
232static int x25_rx(struct sk_buff *skb)
233{
234	struct net_device *dev = skb->dev;
235	hdlc_device *hdlc = dev_to_hdlc(dev);
236	struct x25_state *x25st = state(hdlc);
237
238	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
239		dev->stats.rx_dropped++;
240		return NET_RX_DROP;
241	}
242
243	spin_lock_bh(&x25st->up_lock);
244	if (!x25st->up) {
245		spin_unlock_bh(&x25st->up_lock);
246		kfree_skb(skb);
247		dev->stats.rx_dropped++;
248		return NET_RX_DROP;
249	}
250
251	if (lapb_data_received(dev, skb) == LAPB_OK) {
252		spin_unlock_bh(&x25st->up_lock);
253		return NET_RX_SUCCESS;
254	}
255
256	spin_unlock_bh(&x25st->up_lock);
257	dev->stats.rx_errors++;
258	dev_kfree_skb_any(skb);
259	return NET_RX_DROP;
260}
261
262
263static struct hdlc_proto proto = {
264	.open		= x25_open,
265	.close		= x25_close,
266	.ioctl		= x25_ioctl,
267	.netif_rx	= x25_rx,
268	.xmit		= x25_xmit,
269	.module		= THIS_MODULE,
270};
271
272
273static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
274{
275	x25_hdlc_proto __user *x25_s = ifr->ifr_settings.ifs_ifsu.x25;
276	const size_t size = sizeof(x25_hdlc_proto);
277	hdlc_device *hdlc = dev_to_hdlc(dev);
278	x25_hdlc_proto new_settings;
279	int result;
280
281	switch (ifr->ifr_settings.type) {
282	case IF_GET_PROTO:
283		if (dev_to_hdlc(dev)->proto != &proto)
284			return -EINVAL;
285		ifr->ifr_settings.type = IF_PROTO_X25;
286		if (ifr->ifr_settings.size < size) {
287			ifr->ifr_settings.size = size; /* data size wanted */
288			return -ENOBUFS;
289		}
290		if (copy_to_user(x25_s, &state(hdlc)->settings, size))
291			return -EFAULT;
292		return 0;
293
294	case IF_PROTO_X25:
295		if (!capable(CAP_NET_ADMIN))
296			return -EPERM;
297
298		if (dev->flags & IFF_UP)
299			return -EBUSY;
300
301		/* backward compatibility */
302		if (ifr->ifr_settings.size == 0) {
303			new_settings.dce = 0;
304			new_settings.modulo = 8;
305			new_settings.window = 7;
306			new_settings.t1 = 3;
307			new_settings.t2 = 1;
308			new_settings.n2 = 10;
309		}
310		else {
311			if (copy_from_user(&new_settings, x25_s, size))
312				return -EFAULT;
313
314			if ((new_settings.dce != 0 &&
315			new_settings.dce != 1) ||
316			(new_settings.modulo != 8 &&
317			new_settings.modulo != 128) ||
318			new_settings.window < 1 ||
319			(new_settings.modulo == 8 &&
320			new_settings.window > 7) ||
321			(new_settings.modulo == 128 &&
322			new_settings.window > 127) ||
323			new_settings.t1 < 1 ||
324			new_settings.t1 > 255 ||
325			new_settings.t2 < 1 ||
326			new_settings.t2 > 255 ||
327			new_settings.n2 < 1 ||
328			new_settings.n2 > 255)
329				return -EINVAL;
330		}
331
332		result=hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
333		if (result)
334			return result;
335
336		if ((result = attach_hdlc_protocol(dev, &proto,
337						   sizeof(struct x25_state))))
338			return result;
339
340		memcpy(&state(hdlc)->settings, &new_settings, size);
341		state(hdlc)->up = false;
342		spin_lock_init(&state(hdlc)->up_lock);
343
344		/* There's no header_ops so hard_header_len should be 0. */
345		dev->hard_header_len = 0;
346		/* When transmitting data:
347		 * first we'll remove a pseudo header of 1 byte,
348		 * then we'll prepend an LAPB header of at most 3 bytes.
349		 */
350		dev->needed_headroom = 3 - 1;
351
352		dev->type = ARPHRD_X25;
353		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
354		netif_dormant_off(dev);
355		return 0;
356	}
357
358	return -EINVAL;
359}
360
361
362static int __init mod_init(void)
363{
364	register_hdlc_protocol(&proto);
365	return 0;
366}
367
368
369
370static void __exit mod_exit(void)
371{
372	unregister_hdlc_protocol(&proto);
373}
374
375
376module_init(mod_init);
377module_exit(mod_exit);
378
379MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
380MODULE_DESCRIPTION("X.25 protocol support for generic HDLC");
381MODULE_LICENSE("GPL v2");
382