1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Generic HDLC support routines for Linux
4 * X.25 support
5 *
6 * Copyright (C) 1999 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
7 */
8
9 #include <linux/errno.h>
10 #include <linux/gfp.h>
11 #include <linux/hdlc.h>
12 #include <linux/if_arp.h>
13 #include <linux/inetdevice.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/lapb.h>
17 #include <linux/module.h>
18 #include <linux/pkt_sched.h>
19 #include <linux/poll.h>
20 #include <linux/rtnetlink.h>
21 #include <linux/skbuff.h>
22 #include <net/x25device.h>
23
24 struct x25_state {
25 x25_hdlc_proto settings;
26 bool up;
27 spinlock_t up_lock; /* Protects "up" */
28 struct sk_buff_head rx_queue;
29 struct tasklet_struct rx_tasklet;
30 };
31
32 static int x25_ioctl(struct net_device *dev, struct if_settings *ifs);
33
state(hdlc_device * hdlc)34 static struct x25_state *state(hdlc_device *hdlc)
35 {
36 return hdlc->state;
37 }
38
x25_rx_queue_kick(struct tasklet_struct * t)39 static void x25_rx_queue_kick(struct tasklet_struct *t)
40 {
41 struct x25_state *x25st = from_tasklet(x25st, t, rx_tasklet);
42 struct sk_buff *skb = skb_dequeue(&x25st->rx_queue);
43
44 while (skb) {
45 netif_receive_skb_core(skb);
46 skb = skb_dequeue(&x25st->rx_queue);
47 }
48 }
49
50 /* These functions are callbacks called by LAPB layer */
51
x25_connect_disconnect(struct net_device * dev,int reason,int code)52 static void x25_connect_disconnect(struct net_device *dev, int reason, int code)
53 {
54 struct x25_state *x25st = state(dev_to_hdlc(dev));
55 struct sk_buff *skb;
56 unsigned char *ptr;
57
58 skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
59 if (!skb)
60 return;
61
62 ptr = skb_put(skb, 1);
63 *ptr = code;
64
65 skb->protocol = x25_type_trans(skb, dev);
66
67 skb_queue_tail(&x25st->rx_queue, skb);
68 tasklet_schedule(&x25st->rx_tasklet);
69 }
70
x25_connected(struct net_device * dev,int reason)71 static void x25_connected(struct net_device *dev, int reason)
72 {
73 x25_connect_disconnect(dev, reason, X25_IFACE_CONNECT);
74 }
75
x25_disconnected(struct net_device * dev,int reason)76 static void x25_disconnected(struct net_device *dev, int reason)
77 {
78 x25_connect_disconnect(dev, reason, X25_IFACE_DISCONNECT);
79 }
80
x25_data_indication(struct net_device * dev,struct sk_buff * skb)81 static int x25_data_indication(struct net_device *dev, struct sk_buff *skb)
82 {
83 struct x25_state *x25st = state(dev_to_hdlc(dev));
84 unsigned char *ptr;
85
86 if (skb_cow(skb, 1)) {
87 kfree_skb(skb);
88 return NET_RX_DROP;
89 }
90
91 skb_push(skb, 1);
92
93 ptr = skb->data;
94 *ptr = X25_IFACE_DATA;
95
96 skb->protocol = x25_type_trans(skb, dev);
97
98 skb_queue_tail(&x25st->rx_queue, skb);
99 tasklet_schedule(&x25st->rx_tasklet);
100 return NET_RX_SUCCESS;
101 }
102
x25_data_transmit(struct net_device * dev,struct sk_buff * skb)103 static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb)
104 {
105 hdlc_device *hdlc = dev_to_hdlc(dev);
106
107 skb_reset_network_header(skb);
108 skb->protocol = hdlc_type_trans(skb, dev);
109
110 if (dev_nit_active(dev))
111 dev_queue_xmit_nit(skb, dev);
112
113 hdlc->xmit(skb, dev); /* Ignore return value :-( */
114 }
115
x25_xmit(struct sk_buff * skb,struct net_device * dev)116 static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
117 {
118 hdlc_device *hdlc = dev_to_hdlc(dev);
119 struct x25_state *x25st = state(hdlc);
120 int result;
121
122 /* There should be a pseudo header of 1 byte added by upper layers.
123 * Check to make sure it is there before reading it.
124 */
125 if (skb->len < 1) {
126 kfree_skb(skb);
127 return NETDEV_TX_OK;
128 }
129
130 spin_lock_bh(&x25st->up_lock);
131 if (!x25st->up) {
132 spin_unlock_bh(&x25st->up_lock);
133 kfree_skb(skb);
134 return NETDEV_TX_OK;
135 }
136
137 switch (skb->data[0]) {
138 case X25_IFACE_DATA: /* Data to be transmitted */
139 skb_pull(skb, 1);
140 result = lapb_data_request(dev, skb);
141 if (result != LAPB_OK)
142 dev_kfree_skb(skb);
143 spin_unlock_bh(&x25st->up_lock);
144 return NETDEV_TX_OK;
145
146 case X25_IFACE_CONNECT:
147 result = lapb_connect_request(dev);
148 if (result != LAPB_OK) {
149 if (result == LAPB_CONNECTED)
150 /* Send connect confirm. msg to level 3 */
151 x25_connected(dev, 0);
152 else
153 netdev_err(dev, "LAPB connect request failed, error code = %i\n",
154 result);
155 }
156 break;
157
158 case X25_IFACE_DISCONNECT:
159 result = lapb_disconnect_request(dev);
160 if (result != LAPB_OK) {
161 if (result == LAPB_NOTCONNECTED)
162 /* Send disconnect confirm. msg to level 3 */
163 x25_disconnected(dev, 0);
164 else
165 netdev_err(dev, "LAPB disconnect request failed, error code = %i\n",
166 result);
167 }
168 break;
169
170 default: /* to be defined */
171 break;
172 }
173
174 spin_unlock_bh(&x25st->up_lock);
175 dev_kfree_skb(skb);
176 return NETDEV_TX_OK;
177 }
178
x25_open(struct net_device * dev)179 static int x25_open(struct net_device *dev)
180 {
181 static const struct lapb_register_struct cb = {
182 .connect_confirmation = x25_connected,
183 .connect_indication = x25_connected,
184 .disconnect_confirmation = x25_disconnected,
185 .disconnect_indication = x25_disconnected,
186 .data_indication = x25_data_indication,
187 .data_transmit = x25_data_transmit,
188 };
189 hdlc_device *hdlc = dev_to_hdlc(dev);
190 struct x25_state *x25st = state(hdlc);
191 struct lapb_parms_struct params;
192 int result;
193
194 result = lapb_register(dev, &cb);
195 if (result != LAPB_OK)
196 return -ENOMEM;
197
198 result = lapb_getparms(dev, ¶ms);
199 if (result != LAPB_OK)
200 return -EINVAL;
201
202 if (state(hdlc)->settings.dce)
203 params.mode = params.mode | LAPB_DCE;
204
205 if (state(hdlc)->settings.modulo == 128)
206 params.mode = params.mode | LAPB_EXTENDED;
207
208 params.window = state(hdlc)->settings.window;
209 params.t1 = state(hdlc)->settings.t1;
210 params.t2 = state(hdlc)->settings.t2;
211 params.n2 = state(hdlc)->settings.n2;
212
213 result = lapb_setparms(dev, ¶ms);
214 if (result != LAPB_OK)
215 return -EINVAL;
216
217 spin_lock_bh(&x25st->up_lock);
218 x25st->up = true;
219 spin_unlock_bh(&x25st->up_lock);
220
221 return 0;
222 }
223
x25_close(struct net_device * dev)224 static void x25_close(struct net_device *dev)
225 {
226 hdlc_device *hdlc = dev_to_hdlc(dev);
227 struct x25_state *x25st = state(hdlc);
228
229 spin_lock_bh(&x25st->up_lock);
230 x25st->up = false;
231 spin_unlock_bh(&x25st->up_lock);
232
233 lapb_unregister(dev);
234 tasklet_kill(&x25st->rx_tasklet);
235 }
236
x25_rx(struct sk_buff * skb)237 static int x25_rx(struct sk_buff *skb)
238 {
239 struct net_device *dev = skb->dev;
240 hdlc_device *hdlc = dev_to_hdlc(dev);
241 struct x25_state *x25st = state(hdlc);
242
243 skb = skb_share_check(skb, GFP_ATOMIC);
244 if (!skb) {
245 dev->stats.rx_dropped++;
246 return NET_RX_DROP;
247 }
248
249 spin_lock_bh(&x25st->up_lock);
250 if (!x25st->up) {
251 spin_unlock_bh(&x25st->up_lock);
252 kfree_skb(skb);
253 dev->stats.rx_dropped++;
254 return NET_RX_DROP;
255 }
256
257 if (lapb_data_received(dev, skb) == LAPB_OK) {
258 spin_unlock_bh(&x25st->up_lock);
259 return NET_RX_SUCCESS;
260 }
261
262 spin_unlock_bh(&x25st->up_lock);
263 dev->stats.rx_errors++;
264 dev_kfree_skb_any(skb);
265 return NET_RX_DROP;
266 }
267
268 static struct hdlc_proto proto = {
269 .open = x25_open,
270 .close = x25_close,
271 .ioctl = x25_ioctl,
272 .netif_rx = x25_rx,
273 .xmit = x25_xmit,
274 .module = THIS_MODULE,
275 };
276
x25_ioctl(struct net_device * dev,struct if_settings * ifs)277 static int x25_ioctl(struct net_device *dev, struct if_settings *ifs)
278 {
279 x25_hdlc_proto __user *x25_s = ifs->ifs_ifsu.x25;
280 const size_t size = sizeof(x25_hdlc_proto);
281 hdlc_device *hdlc = dev_to_hdlc(dev);
282 x25_hdlc_proto new_settings;
283 int result;
284
285 switch (ifs->type) {
286 case IF_GET_PROTO:
287 if (dev_to_hdlc(dev)->proto != &proto)
288 return -EINVAL;
289 ifs->type = IF_PROTO_X25;
290 if (ifs->size < size) {
291 ifs->size = size; /* data size wanted */
292 return -ENOBUFS;
293 }
294 if (copy_to_user(x25_s, &state(hdlc)->settings, size))
295 return -EFAULT;
296 return 0;
297
298 case IF_PROTO_X25:
299 if (!capable(CAP_NET_ADMIN))
300 return -EPERM;
301
302 if (dev->flags & IFF_UP)
303 return -EBUSY;
304
305 /* backward compatibility */
306 if (ifs->size == 0) {
307 new_settings.dce = 0;
308 new_settings.modulo = 8;
309 new_settings.window = 7;
310 new_settings.t1 = 3;
311 new_settings.t2 = 1;
312 new_settings.n2 = 10;
313 } else {
314 if (copy_from_user(&new_settings, x25_s, size))
315 return -EFAULT;
316
317 if ((new_settings.dce != 0 &&
318 new_settings.dce != 1) ||
319 (new_settings.modulo != 8 &&
320 new_settings.modulo != 128) ||
321 new_settings.window < 1 ||
322 (new_settings.modulo == 8 &&
323 new_settings.window > 7) ||
324 (new_settings.modulo == 128 &&
325 new_settings.window > 127) ||
326 new_settings.t1 < 1 ||
327 new_settings.t1 > 255 ||
328 new_settings.t2 < 1 ||
329 new_settings.t2 > 255 ||
330 new_settings.n2 < 1 ||
331 new_settings.n2 > 255)
332 return -EINVAL;
333 }
334
335 result = hdlc->attach(dev, ENCODING_NRZ,
336 PARITY_CRC16_PR1_CCITT);
337 if (result)
338 return result;
339
340 result = attach_hdlc_protocol(dev, &proto,
341 sizeof(struct x25_state));
342 if (result)
343 return result;
344
345 memcpy(&state(hdlc)->settings, &new_settings, size);
346 state(hdlc)->up = false;
347 spin_lock_init(&state(hdlc)->up_lock);
348 skb_queue_head_init(&state(hdlc)->rx_queue);
349 tasklet_setup(&state(hdlc)->rx_tasklet, x25_rx_queue_kick);
350
351 /* There's no header_ops so hard_header_len should be 0. */
352 dev->hard_header_len = 0;
353 /* When transmitting data:
354 * first we'll remove a pseudo header of 1 byte,
355 * then we'll prepend an LAPB header of at most 3 bytes.
356 */
357 dev->needed_headroom = 3 - 1;
358
359 dev->type = ARPHRD_X25;
360 call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
361 netif_dormant_off(dev);
362 return 0;
363 }
364
365 return -EINVAL;
366 }
367
hdlc_x25_init(void)368 static int __init hdlc_x25_init(void)
369 {
370 register_hdlc_protocol(&proto);
371 return 0;
372 }
373
hdlc_x25_exit(void)374 static void __exit hdlc_x25_exit(void)
375 {
376 unregister_hdlc_protocol(&proto);
377 }
378
379 module_init(hdlc_x25_init);
380 module_exit(hdlc_x25_exit);
381
382 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
383 MODULE_DESCRIPTION("X.25 protocol support for generic HDLC");
384 MODULE_LICENSE("GPL v2");
385