1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine, randomly fail to work with new
5 * releases, misbehave and/or generally screw up. It might even work.
6 *
7 * This code REQUIRES 2.1.15 or higher
8 *
9 * This module:
10 * This module is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * History
16 * X.25 001 Jonathan Naylor Started coding.
17 * 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
18 */
19
20 #define pr_fmt(fmt) "X25: " fmt
21
22 #include <linux/kernel.h>
23 #include <linux/netdevice.h>
24 #include <linux/skbuff.h>
25 #include <linux/slab.h>
26 #include <net/sock.h>
27 #include <linux/if_arp.h>
28 #include <net/x25.h>
29 #include <net/x25device.h>
30
x25_receive_data(struct sk_buff * skb,struct x25_neigh * nb)31 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
32 {
33 struct sock *sk;
34 unsigned short frametype;
35 unsigned int lci;
36
37 if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
38 return 0;
39
40 frametype = skb->data[2];
41 lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
42
43 /*
44 * LCI of zero is always for us, and its always a link control
45 * frame.
46 */
47 if (lci == 0) {
48 x25_link_control(skb, nb, frametype);
49 return 0;
50 }
51
52 /*
53 * Find an existing socket.
54 */
55 if ((sk = x25_find_socket(lci, nb)) != NULL) {
56 int queued = 1;
57
58 skb_reset_transport_header(skb);
59 bh_lock_sock(sk);
60 if (!sock_owned_by_user(sk)) {
61 queued = x25_process_rx_frame(sk, skb);
62 } else {
63 queued = !sk_add_backlog(sk, skb, sk->sk_rcvbuf);
64 }
65 bh_unlock_sock(sk);
66 sock_put(sk);
67 return queued;
68 }
69
70 /*
71 * Is is a Call Request ? if so process it.
72 */
73 if (frametype == X25_CALL_REQUEST)
74 return x25_rx_call_request(skb, nb, lci);
75
76 /*
77 * Its not a Call Request, nor is it a control frame.
78 * Can we forward it?
79 */
80
81 if (x25_forward_data(lci, nb, skb)) {
82 if (frametype == X25_CLEAR_CONFIRMATION) {
83 x25_clear_forward_by_lci(lci);
84 }
85 kfree_skb(skb);
86 return 1;
87 }
88
89 /*
90 x25_transmit_clear_request(nb, lci, 0x0D);
91 */
92
93 if (frametype != X25_CLEAR_CONFIRMATION)
94 pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
95
96 return 0;
97 }
98
x25_lapb_receive_frame(struct sk_buff * skb,struct net_device * dev,struct packet_type * ptype,struct net_device * orig_dev)99 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
100 struct packet_type *ptype, struct net_device *orig_dev)
101 {
102 struct sk_buff *nskb;
103 struct x25_neigh *nb;
104
105 if (!net_eq(dev_net(dev), &init_net))
106 goto drop;
107
108 nskb = skb_copy(skb, GFP_ATOMIC);
109 if (!nskb)
110 goto drop;
111 kfree_skb(skb);
112 skb = nskb;
113
114 /*
115 * Packet received from unrecognised device, throw it away.
116 */
117 nb = x25_get_neigh(dev);
118 if (!nb) {
119 pr_debug("unknown neighbour - %s\n", dev->name);
120 goto drop;
121 }
122
123 if (!pskb_may_pull(skb, 1))
124 return 0;
125
126 switch (skb->data[0]) {
127
128 case X25_IFACE_DATA:
129 skb_pull(skb, 1);
130 if (x25_receive_data(skb, nb)) {
131 x25_neigh_put(nb);
132 goto out;
133 }
134 break;
135
136 case X25_IFACE_CONNECT:
137 x25_link_established(nb);
138 break;
139
140 case X25_IFACE_DISCONNECT:
141 x25_link_terminated(nb);
142 break;
143 }
144 x25_neigh_put(nb);
145 drop:
146 kfree_skb(skb);
147 out:
148 return 0;
149 }
150
x25_establish_link(struct x25_neigh * nb)151 void x25_establish_link(struct x25_neigh *nb)
152 {
153 struct sk_buff *skb;
154 unsigned char *ptr;
155
156 switch (nb->dev->type) {
157 case ARPHRD_X25:
158 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
159 pr_err("x25_dev: out of memory\n");
160 return;
161 }
162 ptr = skb_put(skb, 1);
163 *ptr = X25_IFACE_CONNECT;
164 break;
165
166 #if IS_ENABLED(CONFIG_LLC)
167 case ARPHRD_ETHER:
168 return;
169 #endif
170 default:
171 return;
172 }
173
174 skb->protocol = htons(ETH_P_X25);
175 skb->dev = nb->dev;
176
177 dev_queue_xmit(skb);
178 }
179
x25_terminate_link(struct x25_neigh * nb)180 void x25_terminate_link(struct x25_neigh *nb)
181 {
182 struct sk_buff *skb;
183 unsigned char *ptr;
184
185 #if IS_ENABLED(CONFIG_LLC)
186 if (nb->dev->type == ARPHRD_ETHER)
187 return;
188 #endif
189 if (nb->dev->type != ARPHRD_X25)
190 return;
191
192 skb = alloc_skb(1, GFP_ATOMIC);
193 if (!skb) {
194 pr_err("x25_dev: out of memory\n");
195 return;
196 }
197
198 ptr = skb_put(skb, 1);
199 *ptr = X25_IFACE_DISCONNECT;
200
201 skb->protocol = htons(ETH_P_X25);
202 skb->dev = nb->dev;
203 dev_queue_xmit(skb);
204 }
205
x25_send_frame(struct sk_buff * skb,struct x25_neigh * nb)206 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
207 {
208 unsigned char *dptr;
209
210 skb_reset_network_header(skb);
211
212 switch (nb->dev->type) {
213 case ARPHRD_X25:
214 dptr = skb_push(skb, 1);
215 *dptr = X25_IFACE_DATA;
216 break;
217
218 #if IS_ENABLED(CONFIG_LLC)
219 case ARPHRD_ETHER:
220 kfree_skb(skb);
221 return;
222 #endif
223 default:
224 kfree_skb(skb);
225 return;
226 }
227
228 skb->protocol = htons(ETH_P_X25);
229 skb->dev = nb->dev;
230
231 dev_queue_xmit(skb);
232 }
233
