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