1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * X.25 Packet Layer release 002
4 *
5 * This is ALPHA test software. This code may break your machine,
6 * randomly fail to work with new releases, misbehave and/or generally
7 * screw up. It might even work.
8 *
9 * This code REQUIRES 2.1.15 or higher
10 *
11 * History
12 * X.25 001 Jonathan Naylor Started coding.
13 * X.25 002 Jonathan Naylor New timer architecture.
14 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
15 * negotiation.
16 * 2000-09-04 Henner Eisen dev_hold() / dev_put() for x25_neigh.
17 */
18
19 #define pr_fmt(fmt) "X25: " fmt
20
21 #include <linux/kernel.h>
22 #include <linux/jiffies.h>
23 #include <linux/timer.h>
24 #include <linux/slab.h>
25 #include <linux/netdevice.h>
26 #include <linux/skbuff.h>
27 #include <linux/uaccess.h>
28 #include <linux/init.h>
29 #include <net/x25.h>
30
31 LIST_HEAD(x25_neigh_list);
32 DEFINE_RWLOCK(x25_neigh_list_lock);
33
34 static void x25_t20timer_expiry(struct timer_list *);
35
36 static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
37 static void x25_transmit_restart_request(struct x25_neigh *nb);
38
39 /*
40 * Linux set/reset timer routines
41 */
x25_start_t20timer(struct x25_neigh * nb)42 static inline void x25_start_t20timer(struct x25_neigh *nb)
43 {
44 mod_timer(&nb->t20timer, jiffies + nb->t20);
45 }
46
x25_t20timer_expiry(struct timer_list * t)47 static void x25_t20timer_expiry(struct timer_list *t)
48 {
49 struct x25_neigh *nb = from_timer(nb, t, t20timer);
50
51 x25_transmit_restart_request(nb);
52
53 x25_start_t20timer(nb);
54 }
55
x25_stop_t20timer(struct x25_neigh * nb)56 static inline void x25_stop_t20timer(struct x25_neigh *nb)
57 {
58 del_timer(&nb->t20timer);
59 }
60
x25_t20timer_pending(struct x25_neigh * nb)61 static inline int x25_t20timer_pending(struct x25_neigh *nb)
62 {
63 return timer_pending(&nb->t20timer);
64 }
65
66 /*
67 * This handles all restart and diagnostic frames.
68 */
x25_link_control(struct sk_buff * skb,struct x25_neigh * nb,unsigned short frametype)69 void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
70 unsigned short frametype)
71 {
72 struct sk_buff *skbn;
73 int confirm;
74
75 switch (frametype) {
76 case X25_RESTART_REQUEST:
77 confirm = !x25_t20timer_pending(nb);
78 x25_stop_t20timer(nb);
79 nb->state = X25_LINK_STATE_3;
80 if (confirm)
81 x25_transmit_restart_confirmation(nb);
82 break;
83
84 case X25_RESTART_CONFIRMATION:
85 x25_stop_t20timer(nb);
86 nb->state = X25_LINK_STATE_3;
87 break;
88
89 case X25_DIAGNOSTIC:
90 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
91 break;
92
93 pr_warn("diagnostic #%d - %02X %02X %02X\n",
94 skb->data[3], skb->data[4],
95 skb->data[5], skb->data[6]);
96 break;
97
98 default:
99 pr_warn("received unknown %02X with LCI 000\n",
100 frametype);
101 break;
102 }
103
104 if (nb->state == X25_LINK_STATE_3)
105 while ((skbn = skb_dequeue(&nb->queue)) != NULL)
106 x25_send_frame(skbn, nb);
107 }
108
109 /*
110 * This routine is called when a Restart Request is needed
111 */
x25_transmit_restart_request(struct x25_neigh * nb)112 static void x25_transmit_restart_request(struct x25_neigh *nb)
113 {
114 unsigned char *dptr;
115 int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
116 struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
117
118 if (!skb)
119 return;
120
121 skb_reserve(skb, X25_MAX_L2_LEN);
122
123 dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
124
125 *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
126 *dptr++ = 0x00;
127 *dptr++ = X25_RESTART_REQUEST;
128 *dptr++ = 0x00;
129 *dptr++ = 0;
130
131 skb->sk = NULL;
132
133 x25_send_frame(skb, nb);
134 }
135
136 /*
137 * This routine is called when a Restart Confirmation is needed
138 */
x25_transmit_restart_confirmation(struct x25_neigh * nb)139 static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
140 {
141 unsigned char *dptr;
142 int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
143 struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
144
145 if (!skb)
146 return;
147
148 skb_reserve(skb, X25_MAX_L2_LEN);
149
150 dptr = skb_put(skb, X25_STD_MIN_LEN);
151
152 *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
153 *dptr++ = 0x00;
154 *dptr++ = X25_RESTART_CONFIRMATION;
155
156 skb->sk = NULL;
157
158 x25_send_frame(skb, nb);
159 }
160
161 /*
162 * This routine is called when a Clear Request is needed outside of the context
163 * of a connected socket.
164 */
x25_transmit_clear_request(struct x25_neigh * nb,unsigned int lci,unsigned char cause)165 void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
166 unsigned char cause)
167 {
168 unsigned char *dptr;
169 int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
170 struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
171
172 if (!skb)
173 return;
174
175 skb_reserve(skb, X25_MAX_L2_LEN);
176
177 dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
178
179 *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
180 X25_GFI_EXTSEQ :
181 X25_GFI_STDSEQ);
182 *dptr++ = (lci >> 0) & 0xFF;
183 *dptr++ = X25_CLEAR_REQUEST;
184 *dptr++ = cause;
185 *dptr++ = 0x00;
186
187 skb->sk = NULL;
188
189 x25_send_frame(skb, nb);
190 }
191
x25_transmit_link(struct sk_buff * skb,struct x25_neigh * nb)192 void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
193 {
194 switch (nb->state) {
195 case X25_LINK_STATE_0:
196 skb_queue_tail(&nb->queue, skb);
197 nb->state = X25_LINK_STATE_1;
198 x25_establish_link(nb);
199 break;
200 case X25_LINK_STATE_1:
201 case X25_LINK_STATE_2:
202 skb_queue_tail(&nb->queue, skb);
203 break;
204 case X25_LINK_STATE_3:
205 x25_send_frame(skb, nb);
206 break;
207 }
208 }
209
210 /*
211 * Called when the link layer has become established.
212 */
x25_link_established(struct x25_neigh * nb)213 void x25_link_established(struct x25_neigh *nb)
214 {
215 switch (nb->state) {
216 case X25_LINK_STATE_0:
217 nb->state = X25_LINK_STATE_2;
218 break;
219 case X25_LINK_STATE_1:
220 x25_transmit_restart_request(nb);
221 nb->state = X25_LINK_STATE_2;
222 x25_start_t20timer(nb);
223 break;
224 }
225 }
226
227 /*
228 * Called when the link layer has terminated, or an establishment
229 * request has failed.
230 */
231
x25_link_terminated(struct x25_neigh * nb)232 void x25_link_terminated(struct x25_neigh *nb)
233 {
234 nb->state = X25_LINK_STATE_0;
235 /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
236 x25_kill_by_neigh(nb);
237 }
238
239 /*
240 * Add a new device.
241 */
x25_link_device_up(struct net_device * dev)242 void x25_link_device_up(struct net_device *dev)
243 {
244 struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
245
246 if (!nb)
247 return;
248
249 skb_queue_head_init(&nb->queue);
250 timer_setup(&nb->t20timer, x25_t20timer_expiry, 0);
251
252 dev_hold(dev);
253 nb->dev = dev;
254 nb->state = X25_LINK_STATE_0;
255 nb->extended = 0;
256 /*
257 * Enables negotiation
258 */
259 nb->global_facil_mask = X25_MASK_REVERSE |
260 X25_MASK_THROUGHPUT |
261 X25_MASK_PACKET_SIZE |
262 X25_MASK_WINDOW_SIZE;
263 nb->t20 = sysctl_x25_restart_request_timeout;
264 refcount_set(&nb->refcnt, 1);
265
266 write_lock_bh(&x25_neigh_list_lock);
267 list_add(&nb->node, &x25_neigh_list);
268 write_unlock_bh(&x25_neigh_list_lock);
269 }
270
271 /**
272 * __x25_remove_neigh - remove neighbour from x25_neigh_list
273 * @nb: - neigh to remove
274 *
275 * Remove neighbour from x25_neigh_list. If it was there.
276 * Caller must hold x25_neigh_list_lock.
277 */
__x25_remove_neigh(struct x25_neigh * nb)278 static void __x25_remove_neigh(struct x25_neigh *nb)
279 {
280 skb_queue_purge(&nb->queue);
281 x25_stop_t20timer(nb);
282
283 if (nb->node.next) {
284 list_del(&nb->node);
285 x25_neigh_put(nb);
286 }
287 }
288
289 /*
290 * A device has been removed, remove its links.
291 */
x25_link_device_down(struct net_device * dev)292 void x25_link_device_down(struct net_device *dev)
293 {
294 struct x25_neigh *nb;
295 struct list_head *entry, *tmp;
296
297 write_lock_bh(&x25_neigh_list_lock);
298
299 list_for_each_safe(entry, tmp, &x25_neigh_list) {
300 nb = list_entry(entry, struct x25_neigh, node);
301
302 if (nb->dev == dev) {
303 __x25_remove_neigh(nb);
304 dev_put(dev);
305 }
306 }
307
308 write_unlock_bh(&x25_neigh_list_lock);
309 }
310
311 /*
312 * Given a device, return the neighbour address.
313 */
x25_get_neigh(struct net_device * dev)314 struct x25_neigh *x25_get_neigh(struct net_device *dev)
315 {
316 struct x25_neigh *nb, *use = NULL;
317 struct list_head *entry;
318
319 read_lock_bh(&x25_neigh_list_lock);
320 list_for_each(entry, &x25_neigh_list) {
321 nb = list_entry(entry, struct x25_neigh, node);
322
323 if (nb->dev == dev) {
324 use = nb;
325 break;
326 }
327 }
328
329 if (use)
330 x25_neigh_hold(use);
331 read_unlock_bh(&x25_neigh_list_lock);
332 return use;
333 }
334
335 /*
336 * Handle the ioctls that control the subscription functions.
337 */
x25_subscr_ioctl(unsigned int cmd,void __user * arg)338 int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
339 {
340 struct x25_subscrip_struct x25_subscr;
341 struct x25_neigh *nb;
342 struct net_device *dev;
343 int rc = -EINVAL;
344
345 if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
346 goto out;
347
348 rc = -EFAULT;
349 if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
350 goto out;
351
352 rc = -EINVAL;
353 if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
354 goto out;
355
356 if ((nb = x25_get_neigh(dev)) == NULL)
357 goto out_dev_put;
358
359 dev_put(dev);
360
361 if (cmd == SIOCX25GSUBSCRIP) {
362 read_lock_bh(&x25_neigh_list_lock);
363 x25_subscr.extended = nb->extended;
364 x25_subscr.global_facil_mask = nb->global_facil_mask;
365 read_unlock_bh(&x25_neigh_list_lock);
366 rc = copy_to_user(arg, &x25_subscr,
367 sizeof(x25_subscr)) ? -EFAULT : 0;
368 } else {
369 rc = -EINVAL;
370 if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
371 rc = 0;
372 write_lock_bh(&x25_neigh_list_lock);
373 nb->extended = x25_subscr.extended;
374 nb->global_facil_mask = x25_subscr.global_facil_mask;
375 write_unlock_bh(&x25_neigh_list_lock);
376 }
377 }
378 x25_neigh_put(nb);
379 out:
380 return rc;
381 out_dev_put:
382 dev_put(dev);
383 goto out;
384 }
385
386
387 /*
388 * Release all memory associated with X.25 neighbour structures.
389 */
x25_link_free(void)390 void __exit x25_link_free(void)
391 {
392 struct x25_neigh *nb;
393 struct list_head *entry, *tmp;
394
395 write_lock_bh(&x25_neigh_list_lock);
396
397 list_for_each_safe(entry, tmp, &x25_neigh_list) {
398 struct net_device *dev;
399
400 nb = list_entry(entry, struct x25_neigh, node);
401 dev = nb->dev;
402 __x25_remove_neigh(nb);
403 dev_put(dev);
404 }
405 write_unlock_bh(&x25_neigh_list_lock);
406 }
407
