// 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 processing.
* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
* negotiation.
* jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
* apr/04/15 Shaun Pereira Fast select with no
* restriction on response.
*/
#define pr_fmt(fmt) "X25: " fmt
#include <linux/slab.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>
/*
* This routine purges all of the queues of frames.
*/
void x25_clear_queues(struct sock *sk)
{
struct x25_sock *x25 = x25_sk(sk);
skb_queue_purge(&sk->sk_write_queue);
skb_queue_purge(&x25->ack_queue);
skb_queue_purge(&x25->interrupt_in_queue);
skb_queue_purge(&x25->interrupt_out_queue);
skb_queue_purge(&x25->fragment_queue);
}
/*
* This routine purges the input queue of those frames that have been
* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
* SDL diagram.
*/
void x25_frames_acked(struct sock *sk, unsigned short nr)
{
struct sk_buff *skb;
struct x25_sock *x25 = x25_sk(sk);
int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
/*
* Remove all the ack-ed frames from the ack queue.
*/
if (x25->va != nr)
while (skb_peek(&x25->ack_queue) && x25->va != nr) {
skb = skb_dequeue(&x25->ack_queue);
kfree_skb(skb);
x25->va = (x25->va + 1) % modulus;
}
}
void x25_requeue_frames(struct sock *sk)
{
struct sk_buff *skb, *skb_prev = NULL;
/*
* Requeue all the un-ack-ed frames on the output queue to be picked
* up by x25_kick. This arrangement handles the possibility of an empty
* output queue.
*/
while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
if (!skb_prev)
skb_queue_head(&sk->sk_write_queue, skb);
else
skb_append(skb_prev, skb, &sk->sk_write_queue);
skb_prev = skb;
}
}
/*
* Validate that the value of nr is between va and vs. Return true or
* false for testing.
*/
int x25_validate_nr(struct sock *sk, unsigned short nr)
{
struct x25_sock *x25 = x25_sk(sk);
unsigned short vc = x25->va;
int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
while (vc != x25->vs) {
if (nr == vc)
return 1;
vc = (vc + 1) % modulus;
}
return nr == x25->vs ? 1 : 0;
}
/*
* This routine is called when the packet layer internally generates a
* control frame.
*/
void x25_write_internal(struct sock *sk, int frametype)
{
struct x25_sock *x25 = x25_sk(sk);
struct sk_buff *skb;
unsigned char *dptr;
unsigned char facilities[X25_MAX_FAC_LEN];
unsigned char addresses[1 + X25_ADDR_LEN];
unsigned char lci1, lci2;
/*
* Default safe frame size.
*/
int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
/*
* Adjust frame size.
*/
switch (frametype) {
case X25_CALL_REQUEST:
len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
break;
case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
if (x25->facilities.reverse & 0x80) {
len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
} else {
len += 1 + X25_MAX_FAC_LEN;
}
break;
case X25_CLEAR_REQUEST:
case X25_RESET_REQUEST:
len += 2;
break;
case X25_RR:
case X25_RNR:
case X25_REJ:
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_CONFIRMATION:
break;
default:
pr_err("invalid frame type %02X\n", frametype);
return;
}
if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
return;
/*
* Space for Ethernet and 802.2 LLC headers.
*/
skb_reserve(skb, X25_MAX_L2_LEN);
/*
* Make space for the GFI and LCI, and fill them in.
*/
dptr = skb_put(skb, 2);
lci1 = (x25->lci >> 8) & 0x0F;
lci2 = (x25->lci >> 0) & 0xFF;
if (x25->neighbour->extended) {
*dptr++ = lci1 | X25_GFI_EXTSEQ;
*dptr++ = lci2;
} else {
*dptr++ = lci1 | X25_GFI_STDSEQ;
*dptr++ = lci2;
}
/*
* Now fill in the frame type specific information.
*/
switch (frametype) {
case X25_CALL_REQUEST:
dptr = skb_put(skb, 1);
*dptr++ = X25_CALL_REQUEST;
len = x25_addr_aton(addresses, &x25->dest_addr,
&x25->source_addr);
skb_put_data(skb, addresses, len);
len = x25_create_facilities(facilities,
&x25->facilities,
&x25->dte_facilities,
x25->neighbour->global_facil_mask);
skb_put_data(skb, facilities, len);
skb_put_data(skb, x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
x25->calluserdata.cudlength = 0;
break;
case X25_CALL_ACCEPTED:
dptr = skb_put(skb, 2);
*dptr++ = X25_CALL_ACCEPTED;
*dptr++ = 0x00; /* Address lengths */
len = x25_create_facilities(facilities,
&x25->facilities,
&x25->dte_facilities,
x25->vc_facil_mask);
skb_put_data(skb, facilities, len);
/* fast select with no restriction on response
allows call user data. Userland must
ensure it is ours and not theirs */
if(x25->facilities.reverse & 0x80) {
skb_put_data(skb,
x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
}
x25->calluserdata.cudlength = 0;
break;
case X25_CLEAR_REQUEST:
dptr = skb_put(skb, 3);
*dptr++ = frametype;
*dptr++ = x25->causediag.cause;
*dptr++ = x25->causediag.diagnostic;
break;
case X25_RESET_REQUEST:
dptr = skb_put(skb, 3);
*dptr++ = frametype;
*dptr++ = 0x00; /* XXX */
*dptr++ = 0x00; /* XXX */
break;
case X25_RR:
case X25_RNR:
case X25_REJ:
if (x25->neighbour->extended) {
dptr = skb_put(skb, 2);
*dptr++ = frametype;
*dptr++ = (x25->vr << 1) & 0xFE;
} else {
dptr = skb_put(skb, 1);
*dptr = frametype;
*dptr++ |= (x25->vr << 5) & 0xE0;
}
break;
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_CONFIRMATION:
dptr = skb_put(skb, 1);
*dptr = frametype;
break;
}
x25_transmit_link(skb, x25->neighbour);
}
/*
* Unpick the contents of the passed X.25 Packet Layer frame.
*/
int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
int *d, int *m)
{
struct x25_sock *x25 = x25_sk(sk);
unsigned char *frame;
if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
return X25_ILLEGAL;
frame = skb->data;
*ns = *nr = *q = *d = *m = 0;
switch (frame[2]) {
case X25_CALL_REQUEST:
case X25_CALL_ACCEPTED:
case X25_CLEAR_REQUEST:
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_REQUEST:
case X25_RESET_CONFIRMATION:
case X25_RESTART_REQUEST:
case X25_RESTART_CONFIRMATION:
case X25_REGISTRATION_REQUEST:
case X25_REGISTRATION_CONFIRMATION:
case X25_DIAGNOSTIC:
return frame[2];
}
if (x25->neighbour->extended) {
if (frame[2] == X25_RR ||
frame[2] == X25_RNR ||
frame[2] == X25_REJ) {
if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
return X25_ILLEGAL;
frame = skb->data;
*nr = (frame[3] >> 1) & 0x7F;
return frame[2];
}
} else {
if ((frame[2] & 0x1F) == X25_RR ||
(frame[2] & 0x1F) == X25_RNR ||
(frame[2] & 0x1F) == X25_REJ) {
*nr = (frame[2] >> 5) & 0x07;
return frame[2] & 0x1F;
}
}
if (x25->neighbour->extended) {
if ((frame[2] & 0x01) == X25_DATA) {
if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
return X25_ILLEGAL;
frame = skb->data;
*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
*m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
*nr = (frame[3] >> 1) & 0x7F;
*ns = (frame[2] >> 1) & 0x7F;
return X25_DATA;
}
} else {
if ((frame[2] & 0x01) == X25_DATA) {
*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
*m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
*nr = (frame[2] >> 5) & 0x07;
*ns = (frame[2] >> 1) & 0x07;
return X25_DATA;
}
}
pr_debug("invalid PLP frame %3ph\n", frame);
return X25_ILLEGAL;
}
void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
unsigned char diagnostic)
{
struct x25_sock *x25 = x25_sk(sk);
x25_clear_queues(sk);
x25_stop_timer(sk);
x25->lci = 0;
x25->state = X25_STATE_0;
x25->causediag.cause = cause;
x25->causediag.diagnostic = diagnostic;
sk->sk_state = TCP_CLOSE;
sk->sk_err = reason;
sk->sk_shutdown |= SEND_SHUTDOWN;
if (!sock_flag(sk, SOCK_DEAD)) {
sk->sk_state_change(sk);
sock_set_flag(sk, SOCK_DEAD);
}
}
/*
* Clear an own-rx-busy condition and tell the peer about this, provided
* that there is a significant amount of free receive buffer space available.
*/
void x25_check_rbuf(struct sock *sk)
{
struct x25_sock *x25 = x25_sk(sk);
if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
(x25->condition & X25_COND_OWN_RX_BUSY)) {
x25->condition &= ~X25_COND_OWN_RX_BUSY;
x25->condition &= ~X25_COND_ACK_PENDING;
x25->vl = x25->vr;
x25_write_internal(sk, X25_RR);
x25_stop_timer(sk);
}
}