aboutsummaryrefslogtreecommitdiffstats
path: root/net/ax25/ax25_in.c
blob: 96f4cab3a2f96c09176e3cb686657c0d9892d0aa (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>

/*
 *	Given a fragment, queue it on the fragment queue and if the fragment
 *	is complete, send it back to ax25_rx_iframe.
 */
static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
{
	struct sk_buff *skbn, *skbo;

	if (ax25->fragno != 0) {
		if (!(*skb->data & AX25_SEG_FIRST)) {
			if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
				/* Enqueue fragment */
				ax25->fragno = *skb->data & AX25_SEG_REM;
				skb_pull(skb, 1);	/* skip fragno */
				ax25->fraglen += skb->len;
				skb_queue_tail(&ax25->frag_queue, skb);

				/* Last fragment received ? */
				if (ax25->fragno == 0) {
					skbn = alloc_skb(AX25_MAX_HEADER_LEN +
							 ax25->fraglen,
							 GFP_ATOMIC);
					if (!skbn) {
						skb_queue_purge(&ax25->frag_queue);
						return 1;
					}

					skb_reserve(skbn, AX25_MAX_HEADER_LEN);

					skbn->dev   = ax25->ax25_dev->dev;
					skb_reset_network_header(skbn);
					skb_reset_transport_header(skbn);

					/* Copy data from the fragments */
					while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
						skb_copy_from_linear_data(skbo,
							  skb_put(skbn, skbo->len),
									  skbo->len);
						kfree_skb(skbo);
					}

					ax25->fraglen = 0;

					if (ax25_rx_iframe(ax25, skbn) == 0)
						kfree_skb(skbn);
				}

				return 1;
			}
		}
	} else {
		/* First fragment received */
		if (*skb->data & AX25_SEG_FIRST) {
			skb_queue_purge(&ax25->frag_queue);
			ax25->fragno = *skb->data & AX25_SEG_REM;
			skb_pull(skb, 1);		/* skip fragno */
			ax25->fraglen = skb->len;
			skb_queue_tail(&ax25->frag_queue, skb);
			return 1;
		}
	}

	return 0;
}

/*
 *	This is where all valid I frames are sent to, to be dispatched to
 *	whichever protocol requires them.
 */
int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
{
	int (*func)(struct sk_buff *, ax25_cb *);
	unsigned char pid;
	int queued = 0;

	if (skb == NULL) return 0;

	ax25_start_idletimer(ax25);

	pid = *skb->data;

	if (pid == AX25_P_IP) {
		/* working around a TCP bug to keep additional listeners
		 * happy. TCP re-uses the buffer and destroys the original
		 * content.
		 */
		struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
		if (skbn != NULL) {
			kfree_skb(skb);
			skb = skbn;
		}

		skb_pull(skb, 1);	/* Remove PID */
		skb->mac_header = skb->network_header;
		skb_reset_network_header(skb);
		skb->dev      = ax25->ax25_dev->dev;
		skb->pkt_type = PACKET_HOST;
		skb->protocol = htons(ETH_P_IP);
		netif_rx(skb);
		return 1;
	}
	if (pid == AX25_P_SEGMENT) {
		skb_pull(skb, 1);	/* Remove PID */
		return ax25_rx_fragment(ax25, skb);
	}

	if ((func = ax25_protocol_function(pid)) != NULL) {
		skb_pull(skb, 1);	/* Remove PID */
		return (*func)(skb, ax25);
	}

	if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
		if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
		    ax25->pidincl) {
			if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
				queued = 1;
			else
				ax25->condition |= AX25_COND_OWN_RX_BUSY;
		}
	}

	return queued;
}

/*
 *	Higher level upcall for a LAPB frame
 */
static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
{
	int queued = 0;

	if (ax25->state == AX25_STATE_0)
		return 0;

	switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
	case AX25_PROTO_STD_SIMPLEX:
	case AX25_PROTO_STD_DUPLEX:
		queued = ax25_std_frame_in(ax25, skb, type);
		break;

#ifdef CONFIG_AX25_DAMA_SLAVE
	case AX25_PROTO_DAMA_SLAVE:
		if (dama || ax25->ax25_dev->dama.slave)
			queued = ax25_ds_frame_in(ax25, skb, type);
		else
			queued = ax25_std_frame_in(ax25, skb, type);
		break;
#endif
	}

	return queued;
}

static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
	ax25_address *dev_addr, struct packet_type *ptype)
{
	ax25_address src, dest, *next_digi = NULL;
	int type = 0, mine = 0, dama;
	struct sock *make, *sk;
	ax25_digi dp, reverse_dp;
	ax25_cb *ax25;
	ax25_dev *ax25_dev;

	/*
	 *	Process the AX.25/LAPB frame.
	 */

	skb_reset_transport_header(skb);

	if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
		goto free;

	/*
	 *	Parse the address header.
	 */

	if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
		goto free;

	/*
	 *	Ours perhaps ?
	 */
	if (dp.lastrepeat + 1 < dp.ndigi)		/* Not yet digipeated completely */
		next_digi = &dp.calls[dp.lastrepeat + 1];

	/*
	 *	Pull of the AX.25 headers leaving the CTRL/PID bytes
	 */
	skb_pull(skb, ax25_addr_size(&dp));

	/* For our port addresses ? */
	if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
		mine = 1;

	/* Also match on any registered callsign from L3/4 */
	if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
		mine = 1;

	/* UI frame - bypass LAPB processing */
	if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
		skb_set_transport_header(skb, 2); /* skip control and pid */

		ax25_send_to_raw(&dest, skb, skb->data[1]);

		if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
			goto free;

		/* Now we are pointing at the pid byte */
		switch (skb->data[1]) {
		case AX25_P_IP:
			skb_pull(skb,2);		/* drop PID/CTRL */
			skb_reset_transport_header(skb);
			skb_reset_network_header(skb);
			skb->dev      = dev;
			skb->pkt_type = PACKET_HOST;
			skb->protocol = htons(ETH_P_IP);
			netif_rx(skb);
			break;

		case AX25_P_ARP:
			skb_pull(skb,2);
			skb_reset_transport_header(skb);
			skb_reset_network_header(skb);
			skb->dev      = dev;
			skb->pkt_type = PACKET_HOST;
			skb->protocol = htons(ETH_P_ARP);
			netif_rx(skb);
			break;
		case AX25_P_TEXT:
			/* Now find a suitable dgram socket */
			sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
			if (sk != NULL) {
				bh_lock_sock(sk);
				if (atomic_read(&sk->sk_rmem_alloc) >=
				    sk->sk_rcvbuf) {
					kfree_skb(skb);
				} else {
					/*
					 *	Remove the control and PID.
					 */
					skb_pull(skb, 2);
					if (sock_queue_rcv_skb(sk, skb) != 0)
						kfree_skb(skb);
				}
				bh_unlock_sock(sk);
				sock_put(sk);
			} else {
				kfree_skb(skb);
			}
			break;

		default:
			kfree_skb(skb);	/* Will scan SOCK_AX25 RAW sockets */
			break;
		}

		return 0;
	}

	/*
	 *	Is connected mode supported on this device ?
	 *	If not, should we DM the incoming frame (except DMs) or
	 *	silently ignore them. For now we stay quiet.
	 */
	if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
		goto free;

	/* LAPB */

	/* AX.25 state 1-4 */

	ax25_digi_invert(&dp, &reverse_dp);

	if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
		/*
		 *	Process the frame. If it is queued up internally it
		 *	returns one otherwise we free it immediately. This
		 *	routine itself wakes the user context layers so we do
		 *	no further work
		 */
		if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
			kfree_skb(skb);

		ax25_cb_put(ax25);
		return 0;
	}

	/* AX.25 state 0 (disconnected) */

	/* a) received not a SABM(E) */

	if ((*skb->data & ~AX25_PF) != AX25_SABM &&
	    (*skb->data & ~AX25_PF) != AX25_SABME) {
		/*
		 *	Never reply to a DM. Also ignore any connects for
		 *	addresses that are not our interfaces and not a socket.
		 */
		if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
			ax25_return_dm(dev, &src, &dest, &dp);

		goto free;
	}

	/* b) received SABM(E) */

	if (dp.lastrepeat + 1 == dp.ndigi)
		sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
	else
		sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);

	if (sk != NULL) {
		bh_lock_sock(sk);
		if (sk_acceptq_is_full(sk) ||
		    (make = ax25_make_new(sk, ax25_dev)) == NULL) {
			if (mine)
				ax25_return_dm(dev, &src, &dest, &dp);
			kfree_skb(skb);
			bh_unlock_sock(sk);
			sock_put(sk);

			return 0;
		}

		ax25 = ax25_sk(make);
		skb_set_owner_r(skb, make);
		skb_queue_head(&sk->sk_receive_queue, skb);

		make->sk_state = TCP_ESTABLISHED;

		sk->sk_ack_backlog++;
		bh_unlock_sock(sk);
	} else {
		if (!mine)
			goto free;

		if ((ax25 = ax25_create_cb()) == NULL) {
			ax25_return_dm(dev, &src, &dest, &dp);
			goto free;
		}

		ax25_fillin_cb(ax25, ax25_dev);
	}

	ax25->source_addr = dest;
	ax25->dest_addr   = src;

	/*
	 *	Sort out any digipeated paths.
	 */
	if (dp.ndigi && !ax25->digipeat &&
	    (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
		kfree_skb(skb);
		ax25_destroy_socket(ax25);
		if (sk)
			sock_put(sk);
		return 0;
	}

	if (dp.ndigi == 0) {
		kfree(ax25->digipeat);
		ax25->digipeat = NULL;
	} else {
		/* Reverse the source SABM's path */
		memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
	}

	if ((*skb->data & ~AX25_PF) == AX25_SABME) {
		ax25->modulus = AX25_EMODULUS;
		ax25->window  = ax25_dev->values[AX25_VALUES_EWINDOW];
	} else {
		ax25->modulus = AX25_MODULUS;
		ax25->window  = ax25_dev->values[AX25_VALUES_WINDOW];
	}

	ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);

#ifdef CONFIG_AX25_DAMA_SLAVE
	if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
		ax25_dama_on(ax25);
#endif

	ax25->state = AX25_STATE_3;

	ax25_cb_add(ax25);

	ax25_start_heartbeat(ax25);
	ax25_start_t3timer(ax25);
	ax25_start_idletimer(ax25);

	if (sk) {
		if (!sock_flag(sk, SOCK_DEAD))
			sk->sk_data_ready(sk, skb->len);
		sock_put(sk);
	} else {
free:
		kfree_skb(skb);
	}
	return 0;
}

/*
 *	Receive an AX.25 frame via a SLIP interface.
 */
int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
		  struct packet_type *ptype, struct net_device *orig_dev)
{
	skb_orphan(skb);

	if (!net_eq(dev_net(dev), &init_net)) {
		kfree_skb(skb);
		return 0;
	}

	if ((*skb->data & 0x0F) != 0) {
		kfree_skb(skb);	/* Not a KISS data frame */
		return 0;
	}

	skb_pull(skb, AX25_KISS_HEADER_LEN);	/* Remove the KISS byte */

	return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
}