1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * LAPB release 002
4 *
5 * This code REQUIRES 2.1.15 or higher/ NET3.038
6 *
7 * History
8 * LAPB 001 Jonathan Naulor Started Coding
9 * LAPB 002 Jonathan Naylor New timer architecture.
10 * 2000-10-29 Henner Eisen lapb_data_indication() return status.
11 */
12
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14
15 #include <linux/errno.h>
16 #include <linux/types.h>
17 #include <linux/socket.h>
18 #include <linux/in.h>
19 #include <linux/kernel.h>
20 #include <linux/timer.h>
21 #include <linux/string.h>
22 #include <linux/sockios.h>
23 #include <linux/net.h>
24 #include <linux/inet.h>
25 #include <linux/netdevice.h>
26 #include <linux/skbuff.h>
27 #include <linux/slab.h>
28 #include <net/sock.h>
29 #include <linux/uaccess.h>
30 #include <linux/fcntl.h>
31 #include <linux/mm.h>
32 #include <linux/interrupt.h>
33 #include <net/lapb.h>
34
35 /*
36 * State machine for state 0, Disconnected State.
37 * The handling of the timer(s) is in file lapb_timer.c.
38 */
39 static void lapb_state0_machine(struct lapb_cb *lapb, struct sk_buff *skb,
40 struct lapb_frame *frame)
41 {
42 switch (frame->type) {
43 case LAPB_SABM:
44 lapb_dbg(1, "(%p) S0 RX SABM(%d)\n", lapb->dev, frame->pf);
45 if (lapb->mode & LAPB_EXTENDED) {
46 lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
47 lapb->dev, frame->pf);
48 lapb_send_control(lapb, LAPB_DM, frame->pf,
49 LAPB_RESPONSE);
50 } else {
51 lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
52 lapb->dev, frame->pf);
53 lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
54 lapb_send_control(lapb, LAPB_UA, frame->pf,
55 LAPB_RESPONSE);
56 lapb_stop_t1timer(lapb);
57 lapb_stop_t2timer(lapb);
58 lapb->state = LAPB_STATE_3;
59 lapb->condition = 0x00;
60 lapb->n2count = 0;
61 lapb->vs = 0;
62 lapb->vr = 0;
63 lapb->va = 0;
64 lapb_connect_indication(lapb, LAPB_OK);
65 }
66 break;
67
68 case LAPB_SABME:
69 lapb_dbg(1, "(%p) S0 RX SABME(%d)\n", lapb->dev, frame->pf);
70 if (lapb->mode & LAPB_EXTENDED) {
71 lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
72 lapb->dev, frame->pf);
73 lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
74 lapb_send_control(lapb, LAPB_UA, frame->pf,
75 LAPB_RESPONSE);
76 lapb_stop_t1timer(lapb);
77 lapb_stop_t2timer(lapb);
78 lapb->state = LAPB_STATE_3;
79 lapb->condition = 0x00;
80 lapb->n2count = 0;
81 lapb->vs = 0;
82 lapb->vr = 0;
83 lapb->va = 0;
84 lapb_connect_indication(lapb, LAPB_OK);
85 } else {
86 lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
87 lapb->dev, frame->pf);
88 lapb_send_control(lapb, LAPB_DM, frame->pf,
89 LAPB_RESPONSE);
90 }
91 break;
92
93 case LAPB_DISC:
94 lapb_dbg(1, "(%p) S0 RX DISC(%d)\n", lapb->dev, frame->pf);
95 lapb_dbg(1, "(%p) S0 TX UA(%d)\n", lapb->dev, frame->pf);
96 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
97 break;
98
99 default:
100 break;
101 }
102
103 kfree_skb(skb);
104 }
105
106 /*
107 * State machine for state 1, Awaiting Connection State.
108 * The handling of the timer(s) is in file lapb_timer.c.
109 */
110 static void lapb_state1_machine(struct lapb_cb *lapb, struct sk_buff *skb,
111 struct lapb_frame *frame)
112 {
113 switch (frame->type) {
114 case LAPB_SABM:
115 lapb_dbg(1, "(%p) S1 RX SABM(%d)\n", lapb->dev, frame->pf);
116 if (lapb->mode & LAPB_EXTENDED) {
117 lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
118 lapb->dev, frame->pf);
119 lapb_send_control(lapb, LAPB_DM, frame->pf,
120 LAPB_RESPONSE);
121 } else {
122 lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
123 lapb->dev, frame->pf);
124 lapb_send_control(lapb, LAPB_UA, frame->pf,
125 LAPB_RESPONSE);
126 }
127 break;
128
129 case LAPB_SABME:
130 lapb_dbg(1, "(%p) S1 RX SABME(%d)\n", lapb->dev, frame->pf);
131 if (lapb->mode & LAPB_EXTENDED) {
132 lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
133 lapb->dev, frame->pf);
134 lapb_send_control(lapb, LAPB_UA, frame->pf,
135 LAPB_RESPONSE);
136 } else {
137 lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
138 lapb->dev, frame->pf);
139 lapb_send_control(lapb, LAPB_DM, frame->pf,
140 LAPB_RESPONSE);
141 }
142 break;
143
144 case LAPB_DISC:
145 lapb_dbg(1, "(%p) S1 RX DISC(%d)\n", lapb->dev, frame->pf);
146 lapb_dbg(1, "(%p) S1 TX DM(%d)\n", lapb->dev, frame->pf);
147 lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
148 break;
149
150 case LAPB_UA:
151 lapb_dbg(1, "(%p) S1 RX UA(%d)\n", lapb->dev, frame->pf);
152 if (frame->pf) {
153 lapb_dbg(0, "(%p) S1 -> S3\n", lapb->dev);
154 lapb_stop_t1timer(lapb);
155 lapb_stop_t2timer(lapb);
156 lapb->state = LAPB_STATE_3;
157 lapb->condition = 0x00;
158 lapb->n2count = 0;
159 lapb->vs = 0;
160 lapb->vr = 0;
161 lapb->va = 0;
162 lapb_connect_confirmation(lapb, LAPB_OK);
163 }
164 break;
165
166 case LAPB_DM:
167 lapb_dbg(1, "(%p) S1 RX DM(%d)\n", lapb->dev, frame->pf);
168 if (frame->pf) {
169 lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
170 lapb_clear_queues(lapb);
171 lapb->state = LAPB_STATE_0;
172 lapb_start_t1timer(lapb);
173 lapb_stop_t2timer(lapb);
174 lapb_disconnect_indication(lapb, LAPB_REFUSED);
175 }
176 break;
177 }
178
179 kfree_skb(skb);
180 }
181
182 /*
183 * State machine for state 2, Awaiting Release State.
184 * The handling of the timer(s) is in file lapb_timer.c
185 */
186 static void lapb_state2_machine(struct lapb_cb *lapb, struct sk_buff *skb,
187 struct lapb_frame *frame)
188 {
189 switch (frame->type) {
190 case LAPB_SABM:
191 case LAPB_SABME:
192 lapb_dbg(1, "(%p) S2 RX {SABM,SABME}(%d)\n",
193 lapb->dev, frame->pf);
194 lapb_dbg(1, "(%p) S2 TX DM(%d)\n", lapb->dev, frame->pf);
195 lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
196 break;
197
198 case LAPB_DISC:
199 lapb_dbg(1, "(%p) S2 RX DISC(%d)\n", lapb->dev, frame->pf);
200 lapb_dbg(1, "(%p) S2 TX UA(%d)\n", lapb->dev, frame->pf);
201 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
202 break;
203
204 case LAPB_UA:
205 lapb_dbg(1, "(%p) S2 RX UA(%d)\n", lapb->dev, frame->pf);
206 if (frame->pf) {
207 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
208 lapb->state = LAPB_STATE_0;
209 lapb_start_t1timer(lapb);
210 lapb_stop_t2timer(lapb);
211 lapb_disconnect_confirmation(lapb, LAPB_OK);
212 }
213 break;
214
215 case LAPB_DM:
216 lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
217 if (frame->pf) {
218 lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
219 lapb->state = LAPB_STATE_0;
220 lapb_start_t1timer(lapb);
221 lapb_stop_t2timer(lapb);
222 lapb_disconnect_confirmation(lapb, LAPB_NOTCONNECTED);
223 }
224 break;
225
226 case LAPB_I:
227 case LAPB_REJ:
228 case LAPB_RNR:
229 case LAPB_RR:
230 lapb_dbg(1, "(%p) S2 RX {I,REJ,RNR,RR}(%d)\n",
231 lapb->dev, frame->pf);
232 lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
233 if (frame->pf)
234 lapb_send_control(lapb, LAPB_DM, frame->pf,
235 LAPB_RESPONSE);
236 break;
237 }
238
239 kfree_skb(skb);
240 }
241
242 /*
243 * State machine for state 3, Connected State.
244 * The handling of the timer(s) is in file lapb_timer.c
245 */
246 static void lapb_state3_machine(struct lapb_cb *lapb, struct sk_buff *skb,
247 struct lapb_frame *frame)
248 {
249 int queued = 0;
250 int modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS :
251 LAPB_SMODULUS;
252
253 switch (frame->type) {
254 case LAPB_SABM:
255 lapb_dbg(1, "(%p) S3 RX SABM(%d)\n", lapb->dev, frame->pf);
256 if (lapb->mode & LAPB_EXTENDED) {
257 lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
258 lapb->dev, frame->pf);
259 lapb_send_control(lapb, LAPB_DM, frame->pf,
260 LAPB_RESPONSE);
261 } else {
262 lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
263 lapb->dev, frame->pf);
264 lapb_send_control(lapb, LAPB_UA, frame->pf,
265 LAPB_RESPONSE);
266 lapb_stop_t1timer(lapb);
267 lapb_stop_t2timer(lapb);
268 lapb->condition = 0x00;
269 lapb->n2count = 0;
270 lapb->vs = 0;
271 lapb->vr = 0;
272 lapb->va = 0;
273 lapb_requeue_frames(lapb);
274 }
275 break;
276
277 case LAPB_SABME:
278 lapb_dbg(1, "(%p) S3 RX SABME(%d)\n", lapb->dev, frame->pf);
279 if (lapb->mode & LAPB_EXTENDED) {
280 lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
281 lapb->dev, frame->pf);
282 lapb_send_control(lapb, LAPB_UA, frame->pf,
283 LAPB_RESPONSE);
284 lapb_stop_t1timer(lapb);
285 lapb_stop_t2timer(lapb);
286 lapb->condition = 0x00;
287 lapb->n2count = 0;
288 lapb->vs = 0;
289 lapb->vr = 0;
290 lapb->va = 0;
291 lapb_requeue_frames(lapb);
292 } else {
293 lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
294 lapb->dev, frame->pf);
295 lapb_send_control(lapb, LAPB_DM, frame->pf,
296 LAPB_RESPONSE);
297 }
298 break;
299
300 case LAPB_DISC:
301 lapb_dbg(1, "(%p) S3 RX DISC(%d)\n", lapb->dev, frame->pf);
302 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
303 lapb_clear_queues(lapb);
304 lapb_send_control(lapb, LAPB_UA, frame->pf, LAPB_RESPONSE);
305 lapb_start_t1timer(lapb);
306 lapb_stop_t2timer(lapb);
307 lapb->state = LAPB_STATE_0;
308 lapb_disconnect_indication(lapb, LAPB_OK);
309 break;
310
311 case LAPB_DM:
312 lapb_dbg(1, "(%p) S3 RX DM(%d)\n", lapb->dev, frame->pf);
313 lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
314 lapb_clear_queues(lapb);
315 lapb->state = LAPB_STATE_0;
316 lapb_start_t1timer(lapb);
317 lapb_stop_t2timer(lapb);
318 lapb_disconnect_indication(lapb, LAPB_NOTCONNECTED);
319 break;
320
321 case LAPB_RNR:
322 lapb_dbg(1, "(%p) S3 RX RNR(%d) R%d\n",
323 lapb->dev, frame->pf, frame->nr);
324 lapb->condition |= LAPB_PEER_RX_BUSY_CONDITION;
325 lapb_check_need_response(lapb, frame->cr, frame->pf);
326 if (lapb_validate_nr(lapb, frame->nr)) {
327 lapb_check_iframes_acked(lapb, frame->nr);
328 } else {
329 lapb->frmr_data = *frame;
330 lapb->frmr_type = LAPB_FRMR_Z;
331 lapb_transmit_frmr(lapb);
332 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
333 lapb_start_t1timer(lapb);
334 lapb_stop_t2timer(lapb);
335 lapb->state = LAPB_STATE_4;
336 lapb->n2count = 0;
337 }
338 break;
339
340 case LAPB_RR:
341 lapb_dbg(1, "(%p) S3 RX RR(%d) R%d\n",
342 lapb->dev, frame->pf, frame->nr);
343 lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
344 lapb_check_need_response(lapb, frame->cr, frame->pf);
345 if (lapb_validate_nr(lapb, frame->nr)) {
346 lapb_check_iframes_acked(lapb, frame->nr);
347 } else {
348 lapb->frmr_data = *frame;
349 lapb->frmr_type = LAPB_FRMR_Z;
350 lapb_transmit_frmr(lapb);
351 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
352 lapb_start_t1timer(lapb);
353 lapb_stop_t2timer(lapb);
354 lapb->state = LAPB_STATE_4;
355 lapb->n2count = 0;
356 }
357 break;
358
359 case LAPB_REJ:
360 lapb_dbg(1, "(%p) S3 RX REJ(%d) R%d\n",
361 lapb->dev, frame->pf, frame->nr);
362 lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
363 lapb_check_need_response(lapb, frame->cr, frame->pf);
364 if (lapb_validate_nr(lapb, frame->nr)) {
365 lapb_frames_acked(lapb, frame->nr);
366 lapb_stop_t1timer(lapb);
367 lapb->n2count = 0;
368 lapb_requeue_frames(lapb);
369 } else {
370 lapb->frmr_data = *frame;
371 lapb->frmr_type = LAPB_FRMR_Z;
372 lapb_transmit_frmr(lapb);
373 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
374 lapb_start_t1timer(lapb);
375 lapb_stop_t2timer(lapb);
376 lapb->state = LAPB_STATE_4;
377 lapb->n2count = 0;
378 }
379 break;
380
381 case LAPB_I:
382 lapb_dbg(1, "(%p) S3 RX I(%d) S%d R%d\n",
383 lapb->dev, frame->pf, frame->ns, frame->nr);
384 if (!lapb_validate_nr(lapb, frame->nr)) {
385 lapb->frmr_data = *frame;
386 lapb->frmr_type = LAPB_FRMR_Z;
387 lapb_transmit_frmr(lapb);
388 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
389 lapb_start_t1timer(lapb);
390 lapb_stop_t2timer(lapb);
391 lapb->state = LAPB_STATE_4;
392 lapb->n2count = 0;
393 break;
394 }
395 if (lapb->condition & LAPB_PEER_RX_BUSY_CONDITION)
396 lapb_frames_acked(lapb, frame->nr);
397 else
398 lapb_check_iframes_acked(lapb, frame->nr);
399
400 if (frame->ns == lapb->vr) {
401 int cn;
402 cn = lapb_data_indication(lapb, skb);
403 queued = 1;
404 /*
405 * If upper layer has dropped the frame, we
406 * basically ignore any further protocol
407 * processing. This will cause the peer
408 * to re-transmit the frame later like
409 * a frame lost on the wire.
410 */
411 if (cn == NET_RX_DROP) {
412 pr_debug("rx congestion\n");
413 break;
414 }
415 lapb->vr = (lapb->vr + 1) % modulus;
416 lapb->condition &= ~LAPB_REJECT_CONDITION;
417 if (frame->pf)
418 lapb_enquiry_response(lapb);
419 else {
420 if (!(lapb->condition &
421 LAPB_ACK_PENDING_CONDITION)) {
422 lapb->condition |= LAPB_ACK_PENDING_CONDITION;
423 lapb_start_t2timer(lapb);
424 }
425 }
426 } else {
427 if (lapb->condition & LAPB_REJECT_CONDITION) {
428 if (frame->pf)
429 lapb_enquiry_response(lapb);
430 } else {
431 lapb_dbg(1, "(%p) S3 TX REJ(%d) R%d\n",
432 lapb->dev, frame->pf, lapb->vr);
433 lapb->condition |= LAPB_REJECT_CONDITION;
434 lapb_send_control(lapb, LAPB_REJ, frame->pf,
435 LAPB_RESPONSE);
436 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
437 }
438 }
439 break;
440
441 case LAPB_FRMR:
442 lapb_dbg(1, "(%p) S3 RX FRMR(%d) %5ph\n",
443 lapb->dev, frame->pf,
444 skb->data);
445 lapb_establish_data_link(lapb);
446 lapb_dbg(0, "(%p) S3 -> S1\n", lapb->dev);
447 lapb_requeue_frames(lapb);
448 lapb->state = LAPB_STATE_1;
449 break;
450
451 case LAPB_ILLEGAL:
452 lapb_dbg(1, "(%p) S3 RX ILLEGAL(%d)\n", lapb->dev, frame->pf);
453 lapb->frmr_data = *frame;
454 lapb->frmr_type = LAPB_FRMR_W;
455 lapb_transmit_frmr(lapb);
456 lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
457 lapb_start_t1timer(lapb);
458 lapb_stop_t2timer(lapb);
459 lapb->state = LAPB_STATE_4;
460 lapb->n2count = 0;
461 break;
462 }
463
464 if (!queued)
465 kfree_skb(skb);
466 }
467
468 /*
469 * State machine for state 4, Frame Reject State.
470 * The handling of the timer(s) is in file lapb_timer.c.
471 */
472 static void lapb_state4_machine(struct lapb_cb *lapb, struct sk_buff *skb,
473 struct lapb_frame *frame)
474 {
475 switch (frame->type) {
476 case LAPB_SABM:
477 lapb_dbg(1, "(%p) S4 RX SABM(%d)\n", lapb->dev, frame->pf);
478 if (lapb->mode & LAPB_EXTENDED) {
479 lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
480 lapb->dev, frame->pf);
481 lapb_send_control(lapb, LAPB_DM, frame->pf,
482 LAPB_RESPONSE);
483 } else {
484 lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
485 lapb->dev, frame->pf);
486 lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
487 lapb_send_control(lapb, LAPB_UA, frame->pf,
488 LAPB_RESPONSE);
489 lapb_stop_t1timer(lapb);
490 lapb_stop_t2timer(lapb);
491 lapb->state = LAPB_STATE_3;
492 lapb->condition = 0x00;
493 lapb->n2count = 0;
494 lapb->vs = 0;
495 lapb->vr = 0;
496 lapb->va = 0;
497 lapb_connect_indication(lapb, LAPB_OK);
498 }
499 break;
500
501 case LAPB_SABME:
502 lapb_dbg(1, "(%p) S4 RX SABME(%d)\n", lapb->dev, frame->pf);
503 if (lapb->mode & LAPB_EXTENDED) {
504 lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
505 lapb->dev, frame->pf);
506 lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
507 lapb_send_control(lapb, LAPB_UA, frame->pf,
508 LAPB_RESPONSE);
509 lapb_stop_t1timer(lapb);
510 lapb_stop_t2timer(lapb);
511 lapb->state = LAPB_STATE_3;
512 lapb->condition = 0x00;
513 lapb->n2count = 0;
514 lapb->vs = 0;
515 lapb->vr = 0;
516 lapb->va = 0;
517 lapb_connect_indication(lapb, LAPB_OK);
518 } else {
519 lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
520 lapb->dev, frame->pf);
521 lapb_send_control(lapb, LAPB_DM, frame->pf,
522 LAPB_RESPONSE);
523 }
524 break;
525 }
526
527 kfree_skb(skb);
528 }
529
530 /*
531 * Process an incoming LAPB frame
532 */
533 void lapb_data_input(struct lapb_cb *lapb, struct sk_buff *skb)
534 {
535 struct lapb_frame frame;
536
537 if (lapb_decode(lapb, skb, &frame) < 0) {
538 kfree_skb(skb);
539 return;
540 }
541
542 switch (lapb->state) {
543 case LAPB_STATE_0:
544 lapb_state0_machine(lapb, skb, &frame); break;
545 case LAPB_STATE_1:
546 lapb_state1_machine(lapb, skb, &frame); break;
547 case LAPB_STATE_2:
548 lapb_state2_machine(lapb, skb, &frame); break;
549 case LAPB_STATE_3:
550 lapb_state3_machine(lapb, skb, &frame); break;
551 case LAPB_STATE_4:
552 lapb_state4_machine(lapb, skb, &frame); break;
553 }
554
555 lapb_kick(lapb);
556 }
557
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