1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
// 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);
return 0;
}
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);
}
|
