[linux-block.git] / net / x25 / x25_in.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	X.25 Packet Layer release 002
 *
 *	This is ALPHA test software. This code may break your machine,
 *	randomly fail to work with new releases, misbehave and/or generally
 *	screw up. It might even work.
 *
 *	This code REQUIRES 2.1.15 or higher
 *
 *	History
 *	X.25 001	Jonathan Naylor	  Started coding.
 *	X.25 002	Jonathan Naylor	  Centralised disconnection code.
 *					  New timer architecture.
 *	2000-03-20	Daniela Squassoni Disabling/enabling of facilities
 *					  negotiation.
 *	2000-11-10	Henner Eisen	  Check and reset for out-of-sequence
 *					  i-frames.
 */

#define pr_fmt(fmt) "X25: " fmt

#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/x25.h>

static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
{
	struct sk_buff *skbo, *skbn = skb;
	struct x25_sock *x25 = x25_sk(sk);

	if (more) {
		x25->fraglen += skb->len;
		skb_queue_tail(&x25->fragment_queue, skb);
		skb_set_owner_r(skb, sk);
		return 0;
	}

	if (x25->fraglen > 0) {	/* End of fragment */
		int len = x25->fraglen + skb->len;

		if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
			kfree_skb(skb);
			return 1;
		}

		skb_queue_tail(&x25->fragment_queue, skb);

		skb_reset_transport_header(skbn);

		skbo = skb_dequeue(&x25->fragment_queue);
		skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
					  skbo->len);
		kfree_skb(skbo);

		while ((skbo =
			skb_dequeue(&x25->fragment_queue)) != NULL) {
			skb_pull(skbo, (x25->neighbour->extended) ?
					X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
			skb_copy_from_linear_data(skbo,
						  skb_put(skbn, skbo->len),
						  skbo->len);
			kfree_skb(skbo);
		}

		x25->fraglen = 0;
	}

	skb_set_owner_r(skbn, sk);
	skb_queue_tail(&sk->sk_receive_queue, skbn);
	if (!sock_flag(sk, SOCK_DEAD))
		sk->sk_data_ready(sk);

	return 0;
}

/*
 * State machine for state 1, Awaiting Call Accepted State.
 * The handling of the timer(s) is in file x25_timer.c.
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	struct x25_address source_addr, dest_addr;
	int len;
	struct x25_sock *x25 = x25_sk(sk);

	switch (frametype) {
	case X25_CALL_ACCEPTED: {

		x25_stop_timer(sk);
		x25->condition = 0x00;
		x25->vs        = 0;
		x25->va        = 0;
		x25->vr        = 0;
		x25->vl        = 0;
		x25->state     = X25_STATE_3;
		sk->sk_state   = TCP_ESTABLISHED;
		/*
		 *	Parse the data in the frame.
		 */
		if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
			goto out_clear;
		skb_pull(skb, X25_STD_MIN_LEN);

		len = x25_parse_address_block(skb, &source_addr,
					      &dest_addr);
		if (len > 0)
			skb_pull(skb, len);
		else if (len < 0)
			goto out_clear;

		len = x25_parse_facilities(skb, &x25->facilities,
					   &x25->dte_facilities,
					   &x25->vc_facil_mask);
		if (len > 0)
			skb_pull(skb, len);
		else if (len < 0)
			goto out_clear;
		/*
		 *	Copy any Call User Data.
		 */
		if (skb->len > 0) {
			if (skb->len > X25_MAX_CUD_LEN)
				goto out_clear;

			skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
				skb->len);
			x25->calluserdata.cudlength = skb->len;
		}
		if (!sock_flag(sk, SOCK_DEAD))
			sk->sk_state_change(sk);
		break;
	}
	case X25_CALL_REQUEST:
		/* call collision */
		x25->causediag.cause      = 0x01;
		x25->causediag.diagnostic = 0x48;

		x25_write_internal(sk, X25_CLEAR_REQUEST);
		x25_disconnect(sk, EISCONN, 0x01, 0x48);
		break;

	case X25_CLEAR_REQUEST:
		if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
			goto out_clear;

		x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
		x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
		break;

	default:
		break;
	}

	return 0;

out_clear:
	x25_write_internal(sk, X25_CLEAR_REQUEST);
	x25->state = X25_STATE_2;
	x25_start_t23timer(sk);
	return 0;
}

/*
 * State machine for state 2, Awaiting Clear Confirmation State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	switch (frametype) {

		case X25_CLEAR_REQUEST:
			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
				goto out_clear;

			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
			break;

		case X25_CLEAR_CONFIRMATION:
			x25_disconnect(sk, 0, 0, 0);
			break;

		default:
			break;
	}

	return 0;

out_clear:
	x25_write_internal(sk, X25_CLEAR_REQUEST);
	x25_start_t23timer(sk);
	return 0;
}

/*
 * State machine for state 3, Connected State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
{
	int queued = 0;
	int modulus;
	struct x25_sock *x25 = x25_sk(sk);

	modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;

	switch (frametype) {

		case X25_RESET_REQUEST:
			x25_write_internal(sk, X25_RESET_CONFIRMATION);
			x25_stop_timer(sk);
			x25->condition = 0x00;
			x25->vs        = 0;
			x25->vr        = 0;
			x25->va        = 0;
			x25->vl        = 0;
			x25_requeue_frames(sk);
			break;

		case X25_CLEAR_REQUEST:
			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
				goto out_clear;

			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
			break;

		case X25_RR:
		case X25_RNR:
			if (!x25_validate_nr(sk, nr)) {
				x25_clear_queues(sk);
				x25_write_internal(sk, X25_RESET_REQUEST);
				x25_start_t22timer(sk);
				x25->condition = 0x00;
				x25->vs        = 0;
				x25->vr        = 0;
				x25->va        = 0;
				x25->vl        = 0;
				x25->state     = X25_STATE_4;
			} else {
				x25_frames_acked(sk, nr);
				if (frametype == X25_RNR) {
					x25->condition |= X25_COND_PEER_RX_BUSY;
				} else {
					x25->condition &= ~X25_COND_PEER_RX_BUSY;
				}
			}
			break;

		case X25_DATA:	/* XXX */
			x25->condition &= ~X25_COND_PEER_RX_BUSY;
			if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
				x25_clear_queues(sk);
				x25_write_internal(sk, X25_RESET_REQUEST);
				x25_start_t22timer(sk);
				x25->condition = 0x00;
				x25->vs        = 0;
				x25->vr        = 0;
				x25->va        = 0;
				x25->vl        = 0;
				x25->state     = X25_STATE_4;
				break;
			}
			x25_frames_acked(sk, nr);
			if (ns == x25->vr) {
				if (x25_queue_rx_frame(sk, skb, m) == 0) {
					x25->vr = (x25->vr + 1) % modulus;
					queued = 1;
				} else {
					/* Should never happen */
					x25_clear_queues(sk);
					x25_write_internal(sk, X25_RESET_REQUEST);
					x25_start_t22timer(sk);
					x25->condition = 0x00;
					x25->vs        = 0;
					x25->vr        = 0;
					x25->va        = 0;
					x25->vl        = 0;
					x25->state     = X25_STATE_4;
					break;
				}
				if (atomic_read(&sk->sk_rmem_alloc) >
				    (sk->sk_rcvbuf >> 1))
					x25->condition |= X25_COND_OWN_RX_BUSY;
			}
			/*
			 *	If the window is full Ack it immediately, else
			 *	start the holdback timer.
			 */
			if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
				x25->condition &= ~X25_COND_ACK_PENDING;
				x25_stop_timer(sk);
				x25_enquiry_response(sk);
			} else {
				x25->condition |= X25_COND_ACK_PENDING;
				x25_start_t2timer(sk);
			}
			break;

		case X25_INTERRUPT_CONFIRMATION:
			clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
			break;

		case X25_INTERRUPT:
			if (sock_flag(sk, SOCK_URGINLINE))
				queued = !sock_queue_rcv_skb(sk, skb);
			else {
				skb_set_owner_r(skb, sk);
				skb_queue_tail(&x25->interrupt_in_queue, skb);
				queued = 1;
			}
			sk_send_sigurg(sk);
			x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
			break;

		default:
			pr_warn("unknown %02X in state 3\n", frametype);
			break;
	}

	return queued;

out_clear:
	x25_write_internal(sk, X25_CLEAR_REQUEST);
	x25->state = X25_STATE_2;
	x25_start_t23timer(sk);
	return 0;
}

/*
 * State machine for state 4, Awaiting Reset Confirmation State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	struct x25_sock *x25 = x25_sk(sk);

	switch (frametype) {

		case X25_RESET_REQUEST:
			x25_write_internal(sk, X25_RESET_CONFIRMATION);
			fallthrough;
		case X25_RESET_CONFIRMATION: {
			x25_stop_timer(sk);
			x25->condition = 0x00;
			x25->va        = 0;
			x25->vr        = 0;
			x25->vs        = 0;
			x25->vl        = 0;
			x25->state     = X25_STATE_3;
			x25_requeue_frames(sk);
			break;
		}
		case X25_CLEAR_REQUEST:
			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
				goto out_clear;

			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
			break;

		default:
			break;
	}

	return 0;

out_clear:
	x25_write_internal(sk, X25_CLEAR_REQUEST);
	x25->state = X25_STATE_2;
	x25_start_t23timer(sk);
	return 0;
}

/*
 * State machine for state 5, Call Accepted / Call Connected pending (X25_ACCPT_APPRV_FLAG).
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
	struct x25_sock *x25 = x25_sk(sk);

	switch (frametype) {
		case X25_CLEAR_REQUEST:
			if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) {
				x25_write_internal(sk, X25_CLEAR_REQUEST);
				x25->state = X25_STATE_2;
				x25_start_t23timer(sk);
				return 0;
			}

			x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
			x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
			break;

		default:
			break;
	}

	return 0;
}

/* Higher level upcall for a LAPB frame */
int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
{
	struct x25_sock *x25 = x25_sk(sk);
	int queued = 0, frametype, ns, nr, q, d, m;

	if (x25->state == X25_STATE_0)
		return 0;

	frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);

	switch (x25->state) {
	case X25_STATE_1:
		queued = x25_state1_machine(sk, skb, frametype);
		break;
	case X25_STATE_2:
		queued = x25_state2_machine(sk, skb, frametype);
		break;
	case X25_STATE_3:
		queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
		break;
	case X25_STATE_4:
		queued = x25_state4_machine(sk, skb, frametype);
		break;
	case X25_STATE_5:
		queued = x25_state5_machine(sk, skb, frametype);
		break;
	}

	x25_kick(sk);

	return queued;
}

int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
	int queued = x25_process_rx_frame(sk, skb);

	if (!queued)
		kfree_skb(skb);

	return 0;
}
Commit	Line	Data
ee5d8f4d	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	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
f8e1d201	7	* screw up. It might even work.
1da177e4 LT	8	*
	9	* This code REQUIRES 2.1.15 or higher
	10	*
1da177e4 LT	11	* History
	12	* X.25 001 Jonathan Naylor Started coding.
	13	* X.25 002 Jonathan Naylor Centralised disconnection code.
	14	* New timer architecture.
f8e1d201	15	* 2000-03-20 Daniela Squassoni Disabling/enabling of facilities
1da177e4 LT	16	* negotiation.
	17	* 2000-11-10 Henner Eisen Check and reset for out-of-sequence
	18	* i-frames.
	19	*/
	20
b73e9e3c	21	#define pr_fmt(fmt) "X25: " fmt
b73e9e3c	22
5a0e3ad6	23	#include <linux/slab.h>
1da177e4 LT	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>
c752f073	29	#include <net/tcp_states.h>
1da177e4 LT	30	#include <net/x25.h>
	31
	32	static 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
9745177c	44	if (x25->fraglen > 0) { /* End of fragment */
1da177e4 LT	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
badff6d0	54	skb_reset_transport_header(skbn);
1da177e4 LT	55
1da177e4 LT	56	skbo = skb_dequeue(&x25->fragment_queue);
1a4e2d09 ACM	57	skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
1a4e2d09 ACM	58	skbo->len);
1da177e4 LT	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);
1a4e2d09 ACM	65	skb_copy_from_linear_data(skbo,
	66	skb_put(skbn, skbo->len),
	67	skbo->len);
1da177e4 LT	68	kfree_skb(skbo);
	69	}
	70
f8e1d201	71	x25->fraglen = 0;
1da177e4 LT	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))
676d2369	77	sk->sk_data_ready(sk);
1da177e4 LT	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	*/
	87	static int x25_state1_machine(struct sock sk, struct sk_buff skb, int frametype)
	88	{
	89	struct x25_address source_addr, dest_addr;
f5eb917b	90	int len;
95c30430	91	struct x25_sock *x25 = x25_sk(sk);
1da177e4 LT	92
1da177e4 LT	93	switch (frametype) {
fddc5f3e JP	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	*/
cb101ed2 MD	107	if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
cb101ed2 MD	108	goto out_clear;
fddc5f3e JP	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) {
c7fd0d48 MD	129	if (skb->len > X25_MAX_CUD_LEN)
	130	goto out_clear;
	131
cb101ed2 MD	132	skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
cb101ed2 MD	133	skb->len);
fddc5f3e	134	x25->calluserdata.cudlength = skb->len;
1da177e4	135	}
fddc5f3e JP	136	if (!sock_flag(sk, SOCK_DEAD))
	137	sk->sk_state_change(sk);
	138	break;
	139	}
b020fcf6 MS	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
fddc5f3e	149	case X25_CLEAR_REQUEST:
cb101ed2 MD	150	if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
	151	goto out_clear;
	152
fddc5f3e JP	153	x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
	154	x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
	155	break;
1da177e4	156
fddc5f3e JP	157	default:
fddc5f3e JP	158	break;
1da177e4 LT	159	}
	160
	161	return 0;
95c30430	162
	163	out_clear:
	164	x25_write_internal(sk, X25_CLEAR_REQUEST);
	165	x25->state = X25_STATE_2;
	166	x25_start_t23timer(sk);
	167	return 0;
1da177e4 LT	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	*/
	175	static int x25_state2_machine(struct sock sk, struct sk_buff skb, int frametype)
	176	{
	177	switch (frametype) {
	178
	179	case X25_CLEAR_REQUEST:
cb101ed2 MD	180	if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
	181	goto out_clear;
	182
1da177e4 LT	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;
cb101ed2 MD	196
	197	out_clear:
	198	x25_write_internal(sk, X25_CLEAR_REQUEST);
	199	x25_start_t23timer(sk);
	200	return 0;
1da177e4 LT	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	*/
	208	static 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);
f8e1d201	213
1da177e4 LT	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:
cb101ed2 MD	230	if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
	231	goto out_clear;
	232
1da177e4 LT	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) >
6bf1574e	292	(sk->sk_rcvbuf >> 1))
1da177e4 LT	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:
b7792e34	310	clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
1da177e4 LT	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:
b73e9e3c	326	pr_warn("unknown %02X in state 3\n", frametype);
1da177e4 LT	327	break;
	328	}
	329
	330	return queued;
cb101ed2 MD	331
	332	out_clear:
	333	x25_write_internal(sk, X25_CLEAR_REQUEST);
	334	x25->state = X25_STATE_2;
	335	x25_start_t23timer(sk);
	336	return 0;
1da177e4 LT	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	*/
	344	static int x25_state4_machine(struct sock sk, struct sk_buff skb, int frametype)
	345	{
cb101ed2 MD	346	struct x25_sock *x25 = x25_sk(sk);
cb101ed2 MD	347
1da177e4 LT	348	switch (frametype) {
	349
	350	case X25_RESET_REQUEST:
	351	x25_write_internal(sk, X25_RESET_CONFIRMATION);
df561f66	352	fallthrough;
1da177e4	353	case X25_RESET_CONFIRMATION: {
1da177e4 LT	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:
cb101ed2 MD	365	if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
	366	goto out_clear;
	367
1da177e4 LT	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;
cb101ed2 MD	377
	378	out_clear:
	379	x25_write_internal(sk, X25_CLEAR_REQUEST);
	380	x25->state = X25_STATE_2;
	381	x25_start_t23timer(sk);
	382	return 0;
1da177e4 LT	383	}
1da177e4 LT	384
f8fc57e8 MS	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	*/
	390	static 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
1da177e4 LT	414	/* Higher level upcall for a LAPB frame */
	415	int 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) {
fddc5f3e JP	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;
f8fc57e8 MS	438	case X25_STATE_5:
	439	queued = x25_state5_machine(sk, skb, frametype);
	440	break;
1da177e4 LT	441	}
	442
	443	x25_kick(sk);
	444
	445	return queued;
	446	}
	447
	448	int 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	}