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// 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.
* 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
*/
#define pr_fmt(fmt) "X25: " fmt
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/if_arp.h>
#include <net/x25.h>
#include <net/x25device.h>
static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
{
struct sock *sk;
unsigned short frametype;
unsigned int lci;
if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
return 0;
frametype = skb->data[2];
lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
/*
* LCI of zero is always for us, and its always a link control
* frame.
*/
if (lci == 0) {
x25_link_control(skb, nb, frametype);
return 0;
}
/*
* Find an existing socket.
*/
if ((sk = x25_find_socket(lci, nb)) != NULL) {
int queued = 1;
skb_reset_transport_header(skb);
bh_lock_sock(sk);
if (!sock_owned_by_user(sk)) {
queued = x25_process_rx_frame(sk, skb);
} else {
queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
}
bh_unlock_sock(sk);
sock_put(sk);
return queued;
}
/*
* Is is a Call Request ? if so process it.
*/
if (frametype == X25_CALL_REQUEST)
return x25_rx_call_request(skb, nb, lci);
/*
* Its not a Call Request, nor is it a control frame.
* Can we forward it?
*/
if (x25_forward_data(lci, nb, skb)) {
if (frametype == X25_CLEAR_CONFIRMATION) {
x25_clear_forward_by_lci(lci);
}
kfree_skb(skb);
return 1;
}
/*
x25_transmit_clear_request(nb, lci, 0x0D);
*/
if (frametype != X25_CLEAR_CONFIRMATION)
pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
return 0;
}
int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
struct packet_type *ptype, struct net_device *orig_dev)
{
struct sk_buff *nskb;
struct x25_neigh *nb;
if (!net_eq(dev_net(dev), &init_net))
goto drop;
nskb = skb_copy(skb, GFP_ATOMIC);
if (!nskb)
goto drop;
kfree_skb(skb);
skb = nskb;
/*
* Packet received from unrecognised device, throw it away.
*/
nb = x25_get_neigh(dev);
if (!nb) {
pr_debug("unknown neighbour - %s\n", dev->name);
goto drop;
}
if (!pskb_may_pull(skb, 1)) {
x25_neigh_put(nb);
goto drop;
}
switch (skb->data[0]) {
case X25_IFACE_DATA:
skb_pull(skb, 1);
if (x25_receive_data(skb, nb)) {
x25_neigh_put(nb);
goto out;
}
break;
case X25_IFACE_CONNECT:
x25_link_established(nb);
break;
case X25_IFACE_DISCONNECT:
x25_link_terminated(nb);
break;
}
x25_neigh_put(nb);
drop:
kfree_skb(skb);
out:
return 0;
}
void x25_establish_link(struct x25_neigh *nb)
{
struct sk_buff *skb;
unsigned char *ptr;
switch (nb->dev->type) {
case ARPHRD_X25:
if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
pr_err("x25_dev: out of memory\n");
return;
}
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_CONNECT;
break;
default:
return;
}
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}
void x25_terminate_link(struct x25_neigh *nb)
{
struct sk_buff *skb;
unsigned char *ptr;
if (nb->dev->type != ARPHRD_X25)
return;
skb = alloc_skb(1, GFP_ATOMIC);
if (!skb) {
pr_err("x25_dev: out of memory\n");
return;
}
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_DISCONNECT;
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}
void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
{
unsigned char *dptr;
skb_reset_network_header(skb);
switch (nb->dev->type) {
case ARPHRD_X25:
dptr = skb_push(skb, 1);
*dptr = X25_IFACE_DATA;
break;
default:
kfree_skb(skb);
return;
}
skb->protocol = htons(ETH_P_X25);
skb->dev = nb->dev;
dev_queue_xmit(skb);
}
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