PageRenderTime 38ms CodeModel.GetById 5ms app.highlight 28ms RepoModel.GetById 1ms app.codeStats 0ms

/net/x25/x25_in.c

http://github.com/mirrors/linux
C | 456 lines | 332 code | 66 blank | 58 comment | 51 complexity | d5fbd31d205f4d2fbfe927df89bb64c6 MD5 | raw file
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *	X.25 Packet Layer release 002
  4 *
  5 *	This is ALPHA test software. This code may break your machine,
  6 *	randomly fail to work with new releases, misbehave and/or generally
  7 *	screw up. It might even work.
  8 *
  9 *	This code REQUIRES 2.1.15 or higher
 10 *
 11 *	History
 12 *	X.25 001	Jonathan Naylor	  Started coding.
 13 *	X.25 002	Jonathan Naylor	  Centralised disconnection code.
 14 *					  New timer architecture.
 15 *	2000-03-20	Daniela Squassoni Disabling/enabling of facilities
 16 *					  negotiation.
 17 *	2000-11-10	Henner Eisen	  Check and reset for out-of-sequence
 18 *					  i-frames.
 19 */
 20
 21#define pr_fmt(fmt) "X25: " fmt
 22
 23#include <linux/slab.h>
 24#include <linux/errno.h>
 25#include <linux/kernel.h>
 26#include <linux/string.h>
 27#include <linux/skbuff.h>
 28#include <net/sock.h>
 29#include <net/tcp_states.h>
 30#include <net/x25.h>
 31
 32static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
 33{
 34	struct sk_buff *skbo, *skbn = skb;
 35	struct x25_sock *x25 = x25_sk(sk);
 36
 37	if (more) {
 38		x25->fraglen += skb->len;
 39		skb_queue_tail(&x25->fragment_queue, skb);
 40		skb_set_owner_r(skb, sk);
 41		return 0;
 42	}
 43
 44	if (!more && x25->fraglen > 0) {	/* End of fragment */
 45		int len = x25->fraglen + skb->len;
 46
 47		if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
 48			kfree_skb(skb);
 49			return 1;
 50		}
 51
 52		skb_queue_tail(&x25->fragment_queue, skb);
 53
 54		skb_reset_transport_header(skbn);
 55
 56		skbo = skb_dequeue(&x25->fragment_queue);
 57		skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
 58					  skbo->len);
 59		kfree_skb(skbo);
 60
 61		while ((skbo =
 62			skb_dequeue(&x25->fragment_queue)) != NULL) {
 63			skb_pull(skbo, (x25->neighbour->extended) ?
 64					X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
 65			skb_copy_from_linear_data(skbo,
 66						  skb_put(skbn, skbo->len),
 67						  skbo->len);
 68			kfree_skb(skbo);
 69		}
 70
 71		x25->fraglen = 0;
 72	}
 73
 74	skb_set_owner_r(skbn, sk);
 75	skb_queue_tail(&sk->sk_receive_queue, skbn);
 76	if (!sock_flag(sk, SOCK_DEAD))
 77		sk->sk_data_ready(sk);
 78
 79	return 0;
 80}
 81
 82/*
 83 * State machine for state 1, Awaiting Call Accepted State.
 84 * The handling of the timer(s) is in file x25_timer.c.
 85 * Handling of state 0 and connection release is in af_x25.c.
 86 */
 87static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 88{
 89	struct x25_address source_addr, dest_addr;
 90	int len;
 91	struct x25_sock *x25 = x25_sk(sk);
 92
 93	switch (frametype) {
 94	case X25_CALL_ACCEPTED: {
 95
 96		x25_stop_timer(sk);
 97		x25->condition = 0x00;
 98		x25->vs        = 0;
 99		x25->va        = 0;
100		x25->vr        = 0;
101		x25->vl        = 0;
102		x25->state     = X25_STATE_3;
103		sk->sk_state   = TCP_ESTABLISHED;
104		/*
105		 *	Parse the data in the frame.
106		 */
107		if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
108			goto out_clear;
109		skb_pull(skb, X25_STD_MIN_LEN);
110
111		len = x25_parse_address_block(skb, &source_addr,
112					      &dest_addr);
113		if (len > 0)
114			skb_pull(skb, len);
115		else if (len < 0)
116			goto out_clear;
117
118		len = x25_parse_facilities(skb, &x25->facilities,
119					   &x25->dte_facilities,
120					   &x25->vc_facil_mask);
121		if (len > 0)
122			skb_pull(skb, len);
123		else if (len < 0)
124			goto out_clear;
125		/*
126		 *	Copy any Call User Data.
127		 */
128		if (skb->len > 0) {
129			if (skb->len > X25_MAX_CUD_LEN)
130				goto out_clear;
131
132			skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
133				skb->len);
134			x25->calluserdata.cudlength = skb->len;
135		}
136		if (!sock_flag(sk, SOCK_DEAD))
137			sk->sk_state_change(sk);
138		break;
139	}
140	case X25_CALL_REQUEST:
141		/* call collision */
142		x25->causediag.cause      = 0x01;
143		x25->causediag.diagnostic = 0x48;
144
145		x25_write_internal(sk, X25_CLEAR_REQUEST);
146		x25_disconnect(sk, EISCONN, 0x01, 0x48);
147		break;
148
149	case X25_CLEAR_REQUEST:
150		if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
151			goto out_clear;
152
153		x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
154		x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
155		break;
156
157	default:
158		break;
159	}
160
161	return 0;
162
163out_clear:
164	x25_write_internal(sk, X25_CLEAR_REQUEST);
165	x25->state = X25_STATE_2;
166	x25_start_t23timer(sk);
167	return 0;
168}
169
170/*
171 * State machine for state 2, Awaiting Clear Confirmation State.
172 * The handling of the timer(s) is in file x25_timer.c
173 * Handling of state 0 and connection release is in af_x25.c.
174 */
175static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
176{
177	switch (frametype) {
178
179		case X25_CLEAR_REQUEST:
180			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
181				goto out_clear;
182
183			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
184			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
185			break;
186
187		case X25_CLEAR_CONFIRMATION:
188			x25_disconnect(sk, 0, 0, 0);
189			break;
190
191		default:
192			break;
193	}
194
195	return 0;
196
197out_clear:
198	x25_write_internal(sk, X25_CLEAR_REQUEST);
199	x25_start_t23timer(sk);
200	return 0;
201}
202
203/*
204 * State machine for state 3, Connected State.
205 * The handling of the timer(s) is in file x25_timer.c
206 * Handling of state 0 and connection release is in af_x25.c.
207 */
208static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
209{
210	int queued = 0;
211	int modulus;
212	struct x25_sock *x25 = x25_sk(sk);
213
214	modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
215
216	switch (frametype) {
217
218		case X25_RESET_REQUEST:
219			x25_write_internal(sk, X25_RESET_CONFIRMATION);
220			x25_stop_timer(sk);
221			x25->condition = 0x00;
222			x25->vs        = 0;
223			x25->vr        = 0;
224			x25->va        = 0;
225			x25->vl        = 0;
226			x25_requeue_frames(sk);
227			break;
228
229		case X25_CLEAR_REQUEST:
230			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
231				goto out_clear;
232
233			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
234			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
235			break;
236
237		case X25_RR:
238		case X25_RNR:
239			if (!x25_validate_nr(sk, nr)) {
240				x25_clear_queues(sk);
241				x25_write_internal(sk, X25_RESET_REQUEST);
242				x25_start_t22timer(sk);
243				x25->condition = 0x00;
244				x25->vs        = 0;
245				x25->vr        = 0;
246				x25->va        = 0;
247				x25->vl        = 0;
248				x25->state     = X25_STATE_4;
249			} else {
250				x25_frames_acked(sk, nr);
251				if (frametype == X25_RNR) {
252					x25->condition |= X25_COND_PEER_RX_BUSY;
253				} else {
254					x25->condition &= ~X25_COND_PEER_RX_BUSY;
255				}
256			}
257			break;
258
259		case X25_DATA:	/* XXX */
260			x25->condition &= ~X25_COND_PEER_RX_BUSY;
261			if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
262				x25_clear_queues(sk);
263				x25_write_internal(sk, X25_RESET_REQUEST);
264				x25_start_t22timer(sk);
265				x25->condition = 0x00;
266				x25->vs        = 0;
267				x25->vr        = 0;
268				x25->va        = 0;
269				x25->vl        = 0;
270				x25->state     = X25_STATE_4;
271				break;
272			}
273			x25_frames_acked(sk, nr);
274			if (ns == x25->vr) {
275				if (x25_queue_rx_frame(sk, skb, m) == 0) {
276					x25->vr = (x25->vr + 1) % modulus;
277					queued = 1;
278				} else {
279					/* Should never happen */
280					x25_clear_queues(sk);
281					x25_write_internal(sk, X25_RESET_REQUEST);
282					x25_start_t22timer(sk);
283					x25->condition = 0x00;
284					x25->vs        = 0;
285					x25->vr        = 0;
286					x25->va        = 0;
287					x25->vl        = 0;
288					x25->state     = X25_STATE_4;
289					break;
290				}
291				if (atomic_read(&sk->sk_rmem_alloc) >
292				    (sk->sk_rcvbuf >> 1))
293					x25->condition |= X25_COND_OWN_RX_BUSY;
294			}
295			/*
296			 *	If the window is full Ack it immediately, else
297			 *	start the holdback timer.
298			 */
299			if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
300				x25->condition &= ~X25_COND_ACK_PENDING;
301				x25_stop_timer(sk);
302				x25_enquiry_response(sk);
303			} else {
304				x25->condition |= X25_COND_ACK_PENDING;
305				x25_start_t2timer(sk);
306			}
307			break;
308
309		case X25_INTERRUPT_CONFIRMATION:
310			clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
311			break;
312
313		case X25_INTERRUPT:
314			if (sock_flag(sk, SOCK_URGINLINE))
315				queued = !sock_queue_rcv_skb(sk, skb);
316			else {
317				skb_set_owner_r(skb, sk);
318				skb_queue_tail(&x25->interrupt_in_queue, skb);
319				queued = 1;
320			}
321			sk_send_sigurg(sk);
322			x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
323			break;
324
325		default:
326			pr_warn("unknown %02X in state 3\n", frametype);
327			break;
328	}
329
330	return queued;
331
332out_clear:
333	x25_write_internal(sk, X25_CLEAR_REQUEST);
334	x25->state = X25_STATE_2;
335	x25_start_t23timer(sk);
336	return 0;
337}
338
339/*
340 * State machine for state 4, Awaiting Reset Confirmation State.
341 * The handling of the timer(s) is in file x25_timer.c
342 * Handling of state 0 and connection release is in af_x25.c.
343 */
344static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
345{
346	struct x25_sock *x25 = x25_sk(sk);
347
348	switch (frametype) {
349
350		case X25_RESET_REQUEST:
351			x25_write_internal(sk, X25_RESET_CONFIRMATION);
352			/* fall through */
353		case X25_RESET_CONFIRMATION: {
354			x25_stop_timer(sk);
355			x25->condition = 0x00;
356			x25->va        = 0;
357			x25->vr        = 0;
358			x25->vs        = 0;
359			x25->vl        = 0;
360			x25->state     = X25_STATE_3;
361			x25_requeue_frames(sk);
362			break;
363		}
364		case X25_CLEAR_REQUEST:
365			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
366				goto out_clear;
367
368			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
369			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
370			break;
371
372		default:
373			break;
374	}
375
376	return 0;
377
378out_clear:
379	x25_write_internal(sk, X25_CLEAR_REQUEST);
380	x25->state = X25_STATE_2;
381	x25_start_t23timer(sk);
382	return 0;
383}
384
385/*
386 * State machine for state 5, Call Accepted / Call Connected pending (X25_ACCPT_APPRV_FLAG).
387 * The handling of the timer(s) is in file x25_timer.c
388 * Handling of state 0 and connection release is in af_x25.c.
389 */
390static int x25_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
391{
392	struct x25_sock *x25 = x25_sk(sk);
393
394	switch (frametype) {
395		case X25_CLEAR_REQUEST:
396			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) {
397				x25_write_internal(sk, X25_CLEAR_REQUEST);
398				x25->state = X25_STATE_2;
399				x25_start_t23timer(sk);
400				return 0;
401			}
402
403			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
404			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
405			break;
406
407		default:
408			break;
409	}
410
411	return 0;
412}
413
414/* Higher level upcall for a LAPB frame */
415int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
416{
417	struct x25_sock *x25 = x25_sk(sk);
418	int queued = 0, frametype, ns, nr, q, d, m;
419
420	if (x25->state == X25_STATE_0)
421		return 0;
422
423	frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
424
425	switch (x25->state) {
426	case X25_STATE_1:
427		queued = x25_state1_machine(sk, skb, frametype);
428		break;
429	case X25_STATE_2:
430		queued = x25_state2_machine(sk, skb, frametype);
431		break;
432	case X25_STATE_3:
433		queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
434		break;
435	case X25_STATE_4:
436		queued = x25_state4_machine(sk, skb, frametype);
437		break;
438	case X25_STATE_5:
439		queued = x25_state5_machine(sk, skb, frametype);
440		break;
441	}
442
443	x25_kick(sk);
444
445	return queued;
446}
447
448int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
449{
450	int queued = x25_process_rx_frame(sk, skb);
451
452	if (!queued)
453		kfree_skb(skb);
454
455	return 0;
456}