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-rw-r--r--net/ax25/ax25_in.c470
1 files changed, 470 insertions, 0 deletions
diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c
new file mode 100644
index 000000000000..3dc808fde33f
--- /dev/null
+++ b/net/ax25/ax25_in.c
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1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
8 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
9 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
10 * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
11 */
12#include <linux/config.h>
13#include <linux/errno.h>
14#include <linux/types.h>
15#include <linux/socket.h>
16#include <linux/in.h>
17#include <linux/kernel.h>
18#include <linux/sched.h>
19#include <linux/timer.h>
20#include <linux/string.h>
21#include <linux/sockios.h>
22#include <linux/net.h>
23#include <net/ax25.h>
24#include <linux/inet.h>
25#include <linux/netdevice.h>
26#include <linux/skbuff.h>
27#include <linux/netfilter.h>
28#include <net/sock.h>
29#include <net/ip.h> /* For ip_rcv */
30#include <net/tcp.h>
31#include <net/arp.h> /* For arp_rcv */
32#include <asm/uaccess.h>
33#include <asm/system.h>
34#include <linux/fcntl.h>
35#include <linux/mm.h>
36#include <linux/interrupt.h>
37
38/*
39 * Given a fragment, queue it on the fragment queue and if the fragment
40 * is complete, send it back to ax25_rx_iframe.
41 */
42static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
43{
44 struct sk_buff *skbn, *skbo;
45
46 if (ax25->fragno != 0) {
47 if (!(*skb->data & AX25_SEG_FIRST)) {
48 if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
49 /* Enqueue fragment */
50 ax25->fragno = *skb->data & AX25_SEG_REM;
51 skb_pull(skb, 1); /* skip fragno */
52 ax25->fraglen += skb->len;
53 skb_queue_tail(&ax25->frag_queue, skb);
54
55 /* Last fragment received ? */
56 if (ax25->fragno == 0) {
57 skbn = alloc_skb(AX25_MAX_HEADER_LEN +
58 ax25->fraglen,
59 GFP_ATOMIC);
60 if (!skbn) {
61 skb_queue_purge(&ax25->frag_queue);
62 return 1;
63 }
64
65 skb_reserve(skbn, AX25_MAX_HEADER_LEN);
66
67 skbn->dev = ax25->ax25_dev->dev;
68 skbn->h.raw = skbn->data;
69 skbn->nh.raw = skbn->data;
70
71 /* Copy data from the fragments */
72 while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
73 memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
74 kfree_skb(skbo);
75 }
76
77 ax25->fraglen = 0;
78
79 if (ax25_rx_iframe(ax25, skbn) == 0)
80 kfree_skb(skbn);
81 }
82
83 return 1;
84 }
85 }
86 } else {
87 /* First fragment received */
88 if (*skb->data & AX25_SEG_FIRST) {
89 skb_queue_purge(&ax25->frag_queue);
90 ax25->fragno = *skb->data & AX25_SEG_REM;
91 skb_pull(skb, 1); /* skip fragno */
92 ax25->fraglen = skb->len;
93 skb_queue_tail(&ax25->frag_queue, skb);
94 return 1;
95 }
96 }
97
98 return 0;
99}
100
101/*
102 * This is where all valid I frames are sent to, to be dispatched to
103 * whichever protocol requires them.
104 */
105int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
106{
107 int (*func)(struct sk_buff *, ax25_cb *);
108 volatile int queued = 0;
109 unsigned char pid;
110
111 if (skb == NULL) return 0;
112
113 ax25_start_idletimer(ax25);
114
115 pid = *skb->data;
116
117#ifdef CONFIG_INET
118 if (pid == AX25_P_IP) {
119 /* working around a TCP bug to keep additional listeners
120 * happy. TCP re-uses the buffer and destroys the original
121 * content.
122 */
123 struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
124 if (skbn != NULL) {
125 kfree_skb(skb);
126 skb = skbn;
127 }
128
129 skb_pull(skb, 1); /* Remove PID */
130 skb->h.raw = skb->data;
131 skb->nh.raw = skb->data;
132 skb->dev = ax25->ax25_dev->dev;
133 skb->pkt_type = PACKET_HOST;
134 skb->protocol = htons(ETH_P_IP);
135 ip_rcv(skb, skb->dev, NULL); /* Wrong ptype */
136 return 1;
137 }
138#endif
139 if (pid == AX25_P_SEGMENT) {
140 skb_pull(skb, 1); /* Remove PID */
141 return ax25_rx_fragment(ax25, skb);
142 }
143
144 if ((func = ax25_protocol_function(pid)) != NULL) {
145 skb_pull(skb, 1); /* Remove PID */
146 return (*func)(skb, ax25);
147 }
148
149 if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
150 if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
151 ax25->pidincl) {
152 if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
153 queued = 1;
154 else
155 ax25->condition |= AX25_COND_OWN_RX_BUSY;
156 }
157 }
158
159 return queued;
160}
161
162/*
163 * Higher level upcall for a LAPB frame
164 */
165static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
166{
167 int queued = 0;
168
169 if (ax25->state == AX25_STATE_0)
170 return 0;
171
172 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
173 case AX25_PROTO_STD_SIMPLEX:
174 case AX25_PROTO_STD_DUPLEX:
175 queued = ax25_std_frame_in(ax25, skb, type);
176 break;
177
178#ifdef CONFIG_AX25_DAMA_SLAVE
179 case AX25_PROTO_DAMA_SLAVE:
180 if (dama || ax25->ax25_dev->dama.slave)
181 queued = ax25_ds_frame_in(ax25, skb, type);
182 else
183 queued = ax25_std_frame_in(ax25, skb, type);
184 break;
185#endif
186 }
187
188 return queued;
189}
190
191static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
192 ax25_address *dev_addr, struct packet_type *ptype)
193{
194 ax25_address src, dest, *next_digi = NULL;
195 int type = 0, mine = 0, dama;
196 struct sock *make, *sk;
197 ax25_digi dp, reverse_dp;
198 ax25_cb *ax25;
199 ax25_dev *ax25_dev;
200
201 /*
202 * Process the AX.25/LAPB frame.
203 */
204
205 skb->h.raw = skb->data;
206
207 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
208 kfree_skb(skb);
209 return 0;
210 }
211
212 /*
213 * Parse the address header.
214 */
215
216 if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL) {
217 kfree_skb(skb);
218 return 0;
219 }
220
221 /*
222 * Ours perhaps ?
223 */
224 if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */
225 next_digi = &dp.calls[dp.lastrepeat + 1];
226
227 /*
228 * Pull of the AX.25 headers leaving the CTRL/PID bytes
229 */
230 skb_pull(skb, ax25_addr_size(&dp));
231
232 /* For our port addresses ? */
233 if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
234 mine = 1;
235
236 /* Also match on any registered callsign from L3/4 */
237 if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
238 mine = 1;
239
240 /* UI frame - bypass LAPB processing */
241 if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
242 skb->h.raw = skb->data + 2; /* skip control and pid */
243
244 ax25_send_to_raw(&dest, skb, skb->data[1]);
245
246 if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0) {
247 kfree_skb(skb);
248 return 0;
249 }
250
251 /* Now we are pointing at the pid byte */
252 switch (skb->data[1]) {
253#ifdef CONFIG_INET
254 case AX25_P_IP:
255 skb_pull(skb,2); /* drop PID/CTRL */
256 skb->h.raw = skb->data;
257 skb->nh.raw = skb->data;
258 skb->dev = dev;
259 skb->pkt_type = PACKET_HOST;
260 skb->protocol = htons(ETH_P_IP);
261 ip_rcv(skb, dev, ptype); /* Note ptype here is the wrong one, fix me later */
262 break;
263
264 case AX25_P_ARP:
265 skb_pull(skb,2);
266 skb->h.raw = skb->data;
267 skb->nh.raw = skb->data;
268 skb->dev = dev;
269 skb->pkt_type = PACKET_HOST;
270 skb->protocol = htons(ETH_P_ARP);
271 arp_rcv(skb, dev, ptype); /* Note ptype here is wrong... */
272 break;
273#endif
274 case AX25_P_TEXT:
275 /* Now find a suitable dgram socket */
276 sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
277 if (sk != NULL) {
278 bh_lock_sock(sk);
279 if (atomic_read(&sk->sk_rmem_alloc) >=
280 sk->sk_rcvbuf) {
281 kfree_skb(skb);
282 } else {
283 /*
284 * Remove the control and PID.
285 */
286 skb_pull(skb, 2);
287 if (sock_queue_rcv_skb(sk, skb) != 0)
288 kfree_skb(skb);
289 }
290 bh_unlock_sock(sk);
291 sock_put(sk);
292 } else {
293 kfree_skb(skb);
294 }
295 break;
296
297 default:
298 kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
299 break;
300 }
301
302 return 0;
303 }
304
305 /*
306 * Is connected mode supported on this device ?
307 * If not, should we DM the incoming frame (except DMs) or
308 * silently ignore them. For now we stay quiet.
309 */
310 if (ax25_dev->values[AX25_VALUES_CONMODE] == 0) {
311 kfree_skb(skb);
312 return 0;
313 }
314
315 /* LAPB */
316
317 /* AX.25 state 1-4 */
318
319 ax25_digi_invert(&dp, &reverse_dp);
320
321 if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
322 /*
323 * Process the frame. If it is queued up internally it
324 * returns one otherwise we free it immediately. This
325 * routine itself wakes the user context layers so we do
326 * no further work
327 */
328 if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
329 kfree_skb(skb);
330
331 ax25_cb_put(ax25);
332 return 0;
333 }
334
335 /* AX.25 state 0 (disconnected) */
336
337 /* a) received not a SABM(E) */
338
339 if ((*skb->data & ~AX25_PF) != AX25_SABM &&
340 (*skb->data & ~AX25_PF) != AX25_SABME) {
341 /*
342 * Never reply to a DM. Also ignore any connects for
343 * addresses that are not our interfaces and not a socket.
344 */
345 if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
346 ax25_return_dm(dev, &src, &dest, &dp);
347
348 kfree_skb(skb);
349 return 0;
350 }
351
352 /* b) received SABM(E) */
353
354 if (dp.lastrepeat + 1 == dp.ndigi)
355 sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
356 else
357 sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
358
359 if (sk != NULL) {
360 bh_lock_sock(sk);
361 if (sk_acceptq_is_full(sk) ||
362 (make = ax25_make_new(sk, ax25_dev)) == NULL) {
363 if (mine)
364 ax25_return_dm(dev, &src, &dest, &dp);
365 kfree_skb(skb);
366 bh_unlock_sock(sk);
367 sock_put(sk);
368
369 return 0;
370 }
371
372 ax25 = ax25_sk(make);
373 skb_set_owner_r(skb, make);
374 skb_queue_head(&sk->sk_receive_queue, skb);
375
376 make->sk_state = TCP_ESTABLISHED;
377
378 sk->sk_ack_backlog++;
379 bh_unlock_sock(sk);
380 } else {
381 if (!mine) {
382 kfree_skb(skb);
383 return 0;
384 }
385
386 if ((ax25 = ax25_create_cb()) == NULL) {
387 ax25_return_dm(dev, &src, &dest, &dp);
388 kfree_skb(skb);
389 return 0;
390 }
391
392 ax25_fillin_cb(ax25, ax25_dev);
393 }
394
395 ax25->source_addr = dest;
396 ax25->dest_addr = src;
397
398 /*
399 * Sort out any digipeated paths.
400 */
401 if (dp.ndigi && !ax25->digipeat &&
402 (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
403 kfree_skb(skb);
404 ax25_destroy_socket(ax25);
405 if (sk)
406 sock_put(sk);
407 return 0;
408 }
409
410 if (dp.ndigi == 0) {
411 if (ax25->digipeat != NULL) {
412 kfree(ax25->digipeat);
413 ax25->digipeat = NULL;
414 }
415 } else {
416 /* Reverse the source SABM's path */
417 memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
418 }
419
420 if ((*skb->data & ~AX25_PF) == AX25_SABME) {
421 ax25->modulus = AX25_EMODULUS;
422 ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW];
423 } else {
424 ax25->modulus = AX25_MODULUS;
425 ax25->window = ax25_dev->values[AX25_VALUES_WINDOW];
426 }
427
428 ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
429
430#ifdef CONFIG_AX25_DAMA_SLAVE
431 if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
432 ax25_dama_on(ax25);
433#endif
434
435 ax25->state = AX25_STATE_3;
436
437 ax25_cb_add(ax25);
438
439 ax25_start_heartbeat(ax25);
440 ax25_start_t3timer(ax25);
441 ax25_start_idletimer(ax25);
442
443 if (sk) {
444 if (!sock_flag(sk, SOCK_DEAD))
445 sk->sk_data_ready(sk, skb->len);
446 sock_put(sk);
447 } else
448 kfree_skb(skb);
449
450 return 0;
451}
452
453/*
454 * Receive an AX.25 frame via a SLIP interface.
455 */
456int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
457 struct packet_type *ptype)
458{
459 skb->sk = NULL; /* Initially we don't know who it's for */
460 skb->destructor = NULL; /* Who initializes this, dammit?! */
461
462 if ((*skb->data & 0x0F) != 0) {
463 kfree_skb(skb); /* Not a KISS data frame */
464 return 0;
465 }
466
467 skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */
468
469 return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
470}
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-11 20:11:18 -0500