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TOMOYO Linux Cross Reference
Linux/net/ax25/ax25_in.c

Version: ~ [ linux-4.20-rc6 ] ~ [ linux-4.19.8 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.87 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.144 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.166 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.128 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.61 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.31.14 ] ~ [ linux-2.6.30.10 ] ~ [ linux-2.6.29.6 ] ~ [ linux-2.6.28.10 ] ~ [ linux-2.6.27.62 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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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/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 <net/sock.h>
 27 #include <net/tcp_states.h>
 28 #include <linux/uaccess.h>
 29 #include <linux/fcntl.h>
 30 #include <linux/mm.h>
 31 #include <linux/interrupt.h>
 32 
 33 /*
 34  *      Given a fragment, queue it on the fragment queue and if the fragment
 35  *      is complete, send it back to ax25_rx_iframe.
 36  */
 37 static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
 38 {
 39         struct sk_buff *skbn, *skbo;
 40 
 41         if (ax25->fragno != 0) {
 42                 if (!(*skb->data & AX25_SEG_FIRST)) {
 43                         if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
 44                                 /* Enqueue fragment */
 45                                 ax25->fragno = *skb->data & AX25_SEG_REM;
 46                                 skb_pull(skb, 1);       /* skip fragno */
 47                                 ax25->fraglen += skb->len;
 48                                 skb_queue_tail(&ax25->frag_queue, skb);
 49 
 50                                 /* Last fragment received ? */
 51                                 if (ax25->fragno == 0) {
 52                                         skbn = alloc_skb(AX25_MAX_HEADER_LEN +
 53                                                          ax25->fraglen,
 54                                                          GFP_ATOMIC);
 55                                         if (!skbn) {
 56                                                 skb_queue_purge(&ax25->frag_queue);
 57                                                 return 1;
 58                                         }
 59 
 60                                         skb_reserve(skbn, AX25_MAX_HEADER_LEN);
 61 
 62                                         skbn->dev   = ax25->ax25_dev->dev;
 63                                         skb_reset_network_header(skbn);
 64                                         skb_reset_transport_header(skbn);
 65 
 66                                         /* Copy data from the fragments */
 67                                         while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
 68                                                 skb_copy_from_linear_data(skbo,
 69                                                           skb_put(skbn, skbo->len),
 70                                                                           skbo->len);
 71                                                 kfree_skb(skbo);
 72                                         }
 73 
 74                                         ax25->fraglen = 0;
 75 
 76                                         if (ax25_rx_iframe(ax25, skbn) == 0)
 77                                                 kfree_skb(skbn);
 78                                 }
 79 
 80                                 return 1;
 81                         }
 82                 }
 83         } else {
 84                 /* First fragment received */
 85                 if (*skb->data & AX25_SEG_FIRST) {
 86                         skb_queue_purge(&ax25->frag_queue);
 87                         ax25->fragno = *skb->data & AX25_SEG_REM;
 88                         skb_pull(skb, 1);               /* skip fragno */
 89                         ax25->fraglen = skb->len;
 90                         skb_queue_tail(&ax25->frag_queue, skb);
 91                         return 1;
 92                 }
 93         }
 94 
 95         return 0;
 96 }
 97 
 98 /*
 99  *      This is where all valid I frames are sent to, to be dispatched to
100  *      whichever protocol requires them.
101  */
102 int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
103 {
104         int (*func)(struct sk_buff *, ax25_cb *);
105         unsigned char pid;
106         int queued = 0;
107 
108         if (skb == NULL) return 0;
109 
110         ax25_start_idletimer(ax25);
111 
112         pid = *skb->data;
113 
114         if (pid == AX25_P_IP) {
115                 /* working around a TCP bug to keep additional listeners
116                  * happy. TCP re-uses the buffer and destroys the original
117                  * content.
118                  */
119                 struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
120                 if (skbn != NULL) {
121                         kfree_skb(skb);
122                         skb = skbn;
123                 }
124 
125                 skb_pull(skb, 1);       /* Remove PID */
126                 skb->mac_header = skb->network_header;
127                 skb_reset_network_header(skb);
128                 skb->dev      = ax25->ax25_dev->dev;
129                 skb->pkt_type = PACKET_HOST;
130                 skb->protocol = htons(ETH_P_IP);
131                 netif_rx(skb);
132                 return 1;
133         }
134         if (pid == AX25_P_SEGMENT) {
135                 skb_pull(skb, 1);       /* Remove PID */
136                 return ax25_rx_fragment(ax25, skb);
137         }
138 
139         if ((func = ax25_protocol_function(pid)) != NULL) {
140                 skb_pull(skb, 1);       /* Remove PID */
141                 return (*func)(skb, ax25);
142         }
143 
144         if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
145                 if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
146                     ax25->pidincl) {
147                         if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
148                                 queued = 1;
149                         else
150                                 ax25->condition |= AX25_COND_OWN_RX_BUSY;
151                 }
152         }
153 
154         return queued;
155 }
156 
157 /*
158  *      Higher level upcall for a LAPB frame
159  */
160 static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
161 {
162         int queued = 0;
163 
164         if (ax25->state == AX25_STATE_0)
165                 return 0;
166 
167         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
168         case AX25_PROTO_STD_SIMPLEX:
169         case AX25_PROTO_STD_DUPLEX:
170                 queued = ax25_std_frame_in(ax25, skb, type);
171                 break;
172 
173 #ifdef CONFIG_AX25_DAMA_SLAVE
174         case AX25_PROTO_DAMA_SLAVE:
175                 if (dama || ax25->ax25_dev->dama.slave)
176                         queued = ax25_ds_frame_in(ax25, skb, type);
177                 else
178                         queued = ax25_std_frame_in(ax25, skb, type);
179                 break;
180 #endif
181         }
182 
183         return queued;
184 }
185 
186 static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
187         ax25_address *dev_addr, struct packet_type *ptype)
188 {
189         ax25_address src, dest, *next_digi = NULL;
190         int type = 0, mine = 0, dama;
191         struct sock *make, *sk;
192         ax25_digi dp, reverse_dp;
193         ax25_cb *ax25;
194         ax25_dev *ax25_dev;
195 
196         /*
197          *      Process the AX.25/LAPB frame.
198          */
199 
200         skb_reset_transport_header(skb);
201 
202         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
203                 goto free;
204 
205         /*
206          *      Parse the address header.
207          */
208 
209         if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL)
210                 goto free;
211 
212         /*
213          *      Ours perhaps ?
214          */
215         if (dp.lastrepeat + 1 < dp.ndigi)               /* Not yet digipeated completely */
216                 next_digi = &dp.calls[dp.lastrepeat + 1];
217 
218         /*
219          *      Pull of the AX.25 headers leaving the CTRL/PID bytes
220          */
221         skb_pull(skb, ax25_addr_size(&dp));
222 
223         /* For our port addresses ? */
224         if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
225                 mine = 1;
226 
227         /* Also match on any registered callsign from L3/4 */
228         if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
229                 mine = 1;
230 
231         /* UI frame - bypass LAPB processing */
232         if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
233                 skb_set_transport_header(skb, 2); /* skip control and pid */
234 
235                 ax25_send_to_raw(&dest, skb, skb->data[1]);
236 
237                 if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0)
238                         goto free;
239 
240                 /* Now we are pointing at the pid byte */
241                 switch (skb->data[1]) {
242                 case AX25_P_IP:
243                         skb_pull(skb,2);                /* drop PID/CTRL */
244                         skb_reset_transport_header(skb);
245                         skb_reset_network_header(skb);
246                         skb->dev      = dev;
247                         skb->pkt_type = PACKET_HOST;
248                         skb->protocol = htons(ETH_P_IP);
249                         netif_rx(skb);
250                         break;
251 
252                 case AX25_P_ARP:
253                         skb_pull(skb,2);
254                         skb_reset_transport_header(skb);
255                         skb_reset_network_header(skb);
256                         skb->dev      = dev;
257                         skb->pkt_type = PACKET_HOST;
258                         skb->protocol = htons(ETH_P_ARP);
259                         netif_rx(skb);
260                         break;
261                 case AX25_P_TEXT:
262                         /* Now find a suitable dgram socket */
263                         sk = ax25_get_socket(&dest, &src, SOCK_DGRAM);
264                         if (sk != NULL) {
265                                 bh_lock_sock(sk);
266                                 if (atomic_read(&sk->sk_rmem_alloc) >=
267                                     sk->sk_rcvbuf) {
268                                         kfree_skb(skb);
269                                 } else {
270                                         /*
271                                          *      Remove the control and PID.
272                                          */
273                                         skb_pull(skb, 2);
274                                         if (sock_queue_rcv_skb(sk, skb) != 0)
275                                                 kfree_skb(skb);
276                                 }
277                                 bh_unlock_sock(sk);
278                                 sock_put(sk);
279                         } else {
280                                 kfree_skb(skb);
281                         }
282                         break;
283 
284                 default:
285                         kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
286                         break;
287                 }
288 
289                 return 0;
290         }
291 
292         /*
293          *      Is connected mode supported on this device ?
294          *      If not, should we DM the incoming frame (except DMs) or
295          *      silently ignore them. For now we stay quiet.
296          */
297         if (ax25_dev->values[AX25_VALUES_CONMODE] == 0)
298                 goto free;
299 
300         /* LAPB */
301 
302         /* AX.25 state 1-4 */
303 
304         ax25_digi_invert(&dp, &reverse_dp);
305 
306         if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
307                 /*
308                  *      Process the frame. If it is queued up internally it
309                  *      returns one otherwise we free it immediately. This
310                  *      routine itself wakes the user context layers so we do
311                  *      no further work
312                  */
313                 if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
314                         kfree_skb(skb);
315 
316                 ax25_cb_put(ax25);
317                 return 0;
318         }
319 
320         /* AX.25 state 0 (disconnected) */
321 
322         /* a) received not a SABM(E) */
323 
324         if ((*skb->data & ~AX25_PF) != AX25_SABM &&
325             (*skb->data & ~AX25_PF) != AX25_SABME) {
326                 /*
327                  *      Never reply to a DM. Also ignore any connects for
328                  *      addresses that are not our interfaces and not a socket.
329                  */
330                 if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
331                         ax25_return_dm(dev, &src, &dest, &dp);
332 
333                 goto free;
334         }
335 
336         /* b) received SABM(E) */
337 
338         if (dp.lastrepeat + 1 == dp.ndigi)
339                 sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
340         else
341                 sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
342 
343         if (sk != NULL) {
344                 bh_lock_sock(sk);
345                 if (sk_acceptq_is_full(sk) ||
346                     (make = ax25_make_new(sk, ax25_dev)) == NULL) {
347                         if (mine)
348                                 ax25_return_dm(dev, &src, &dest, &dp);
349                         kfree_skb(skb);
350                         bh_unlock_sock(sk);
351                         sock_put(sk);
352 
353                         return 0;
354                 }
355 
356                 ax25 = sk_to_ax25(make);
357                 skb_set_owner_r(skb, make);
358                 skb_queue_head(&sk->sk_receive_queue, skb);
359 
360                 make->sk_state = TCP_ESTABLISHED;
361 
362                 sk->sk_ack_backlog++;
363                 bh_unlock_sock(sk);
364         } else {
365                 if (!mine)
366                         goto free;
367 
368                 if ((ax25 = ax25_create_cb()) == NULL) {
369                         ax25_return_dm(dev, &src, &dest, &dp);
370                         goto free;
371                 }
372 
373                 ax25_fillin_cb(ax25, ax25_dev);
374         }
375 
376         ax25->source_addr = dest;
377         ax25->dest_addr   = src;
378 
379         /*
380          *      Sort out any digipeated paths.
381          */
382         if (dp.ndigi && !ax25->digipeat &&
383             (ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
384                 kfree_skb(skb);
385                 ax25_destroy_socket(ax25);
386                 if (sk)
387                         sock_put(sk);
388                 return 0;
389         }
390 
391         if (dp.ndigi == 0) {
392                 kfree(ax25->digipeat);
393                 ax25->digipeat = NULL;
394         } else {
395                 /* Reverse the source SABM's path */
396                 memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
397         }
398 
399         if ((*skb->data & ~AX25_PF) == AX25_SABME) {
400                 ax25->modulus = AX25_EMODULUS;
401                 ax25->window  = ax25_dev->values[AX25_VALUES_EWINDOW];
402         } else {
403                 ax25->modulus = AX25_MODULUS;
404                 ax25->window  = ax25_dev->values[AX25_VALUES_WINDOW];
405         }
406 
407         ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
408 
409 #ifdef CONFIG_AX25_DAMA_SLAVE
410         if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
411                 ax25_dama_on(ax25);
412 #endif
413 
414         ax25->state = AX25_STATE_3;
415 
416         ax25_cb_add(ax25);
417 
418         ax25_start_heartbeat(ax25);
419         ax25_start_t3timer(ax25);
420         ax25_start_idletimer(ax25);
421 
422         if (sk) {
423                 if (!sock_flag(sk, SOCK_DEAD))
424                         sk->sk_data_ready(sk);
425                 sock_put(sk);
426         } else {
427 free:
428                 kfree_skb(skb);
429         }
430         return 0;
431 }
432 
433 /*
434  *      Receive an AX.25 frame via a SLIP interface.
435  */
436 int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
437                   struct packet_type *ptype, struct net_device *orig_dev)
438 {
439         skb_orphan(skb);
440 
441         if (!net_eq(dev_net(dev), &init_net)) {
442                 kfree_skb(skb);
443                 return 0;
444         }
445 
446         if ((*skb->data & 0x0F) != 0) {
447                 kfree_skb(skb); /* Not a KISS data frame */
448                 return 0;
449         }
450 
451         skb_pull(skb, AX25_KISS_HEADER_LEN);    /* Remove the KISS byte */
452 
453         return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
454 }
455 

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