1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine,
5 * randomly fail to work with new releases, misbehave and/or generally
6 * screw up. It might even work.
7 *
8 * This code REQUIRES 2.1.15 or higher
9 *
10 * This module:
11 * This module is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 *
16 * History
17 * X.25 001 Jonathan Naylor Started coding.
18 * X.25 002 Jonathan Naylor Centralised disconnection processing.
19 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
20 * negotiation.
21 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
22 * apr/04/15 Shaun Pereira Fast select with no
23 * restriction on response.
24 */
25
26 #define pr_fmt(fmt) "X25: " fmt
27
28 #include <linux/slab.h>
29 #include <linux/kernel.h>
30 #include <linux/string.h>
31 #include <linux/skbuff.h>
32 #include <net/sock.h>
33 #include <net/tcp_states.h>
34 #include <net/x25.h>
35
36 /*
37 * This routine purges all of the queues of frames.
38 */
x25_clear_queues(struct sock * sk)39 void x25_clear_queues(struct sock *sk)
40 {
41 struct x25_sock *x25 = x25_sk(sk);
42
43 skb_queue_purge(&sk->sk_write_queue);
44 skb_queue_purge(&x25->ack_queue);
45 skb_queue_purge(&x25->interrupt_in_queue);
46 skb_queue_purge(&x25->interrupt_out_queue);
47 skb_queue_purge(&x25->fragment_queue);
48 }
49
50
51 /*
52 * This routine purges the input queue of those frames that have been
53 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
54 * SDL diagram.
55 */
x25_frames_acked(struct sock * sk,unsigned short nr)56 void x25_frames_acked(struct sock *sk, unsigned short nr)
57 {
58 struct sk_buff *skb;
59 struct x25_sock *x25 = x25_sk(sk);
60 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
61
62 /*
63 * Remove all the ack-ed frames from the ack queue.
64 */
65 if (x25->va != nr)
66 while (skb_peek(&x25->ack_queue) && x25->va != nr) {
67 skb = skb_dequeue(&x25->ack_queue);
68 kfree_skb(skb);
69 x25->va = (x25->va + 1) % modulus;
70 }
71 }
72
x25_requeue_frames(struct sock * sk)73 void x25_requeue_frames(struct sock *sk)
74 {
75 struct sk_buff *skb, *skb_prev = NULL;
76
77 /*
78 * Requeue all the un-ack-ed frames on the output queue to be picked
79 * up by x25_kick. This arrangement handles the possibility of an empty
80 * output queue.
81 */
82 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
83 if (!skb_prev)
84 skb_queue_head(&sk->sk_write_queue, skb);
85 else
86 skb_append(skb_prev, skb, &sk->sk_write_queue);
87 skb_prev = skb;
88 }
89 }
90
91 /*
92 * Validate that the value of nr is between va and vs. Return true or
93 * false for testing.
94 */
x25_validate_nr(struct sock * sk,unsigned short nr)95 int x25_validate_nr(struct sock *sk, unsigned short nr)
96 {
97 struct x25_sock *x25 = x25_sk(sk);
98 unsigned short vc = x25->va;
99 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
100
101 while (vc != x25->vs) {
102 if (nr == vc)
103 return 1;
104 vc = (vc + 1) % modulus;
105 }
106
107 return nr == x25->vs ? 1 : 0;
108 }
109
110 /*
111 * This routine is called when the packet layer internally generates a
112 * control frame.
113 */
x25_write_internal(struct sock * sk,int frametype)114 void x25_write_internal(struct sock *sk, int frametype)
115 {
116 struct x25_sock *x25 = x25_sk(sk);
117 struct sk_buff *skb;
118 unsigned char *dptr;
119 unsigned char facilities[X25_MAX_FAC_LEN];
120 unsigned char addresses[1 + X25_ADDR_LEN];
121 unsigned char lci1, lci2;
122 /*
123 * Default safe frame size.
124 */
125 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
126
127 /*
128 * Adjust frame size.
129 */
130 switch (frametype) {
131 case X25_CALL_REQUEST:
132 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
133 break;
134 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
135 if (x25->facilities.reverse & 0x80) {
136 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
137 } else {
138 len += 1 + X25_MAX_FAC_LEN;
139 }
140 break;
141 case X25_CLEAR_REQUEST:
142 case X25_RESET_REQUEST:
143 len += 2;
144 break;
145 case X25_RR:
146 case X25_RNR:
147 case X25_REJ:
148 case X25_CLEAR_CONFIRMATION:
149 case X25_INTERRUPT_CONFIRMATION:
150 case X25_RESET_CONFIRMATION:
151 break;
152 default:
153 pr_err("invalid frame type %02X\n", frametype);
154 return;
155 }
156
157 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
158 return;
159
160 /*
161 * Space for Ethernet and 802.2 LLC headers.
162 */
163 skb_reserve(skb, X25_MAX_L2_LEN);
164
165 /*
166 * Make space for the GFI and LCI, and fill them in.
167 */
168 dptr = skb_put(skb, 2);
169
170 lci1 = (x25->lci >> 8) & 0x0F;
171 lci2 = (x25->lci >> 0) & 0xFF;
172
173 if (x25->neighbour->extended) {
174 *dptr++ = lci1 | X25_GFI_EXTSEQ;
175 *dptr++ = lci2;
176 } else {
177 *dptr++ = lci1 | X25_GFI_STDSEQ;
178 *dptr++ = lci2;
179 }
180
181 /*
182 * Now fill in the frame type specific information.
183 */
184 switch (frametype) {
185
186 case X25_CALL_REQUEST:
187 dptr = skb_put(skb, 1);
188 *dptr++ = X25_CALL_REQUEST;
189 len = x25_addr_aton(addresses, &x25->dest_addr,
190 &x25->source_addr);
191 skb_put_data(skb, addresses, len);
192 len = x25_create_facilities(facilities,
193 &x25->facilities,
194 &x25->dte_facilities,
195 x25->neighbour->global_facil_mask);
196 skb_put_data(skb, facilities, len);
197 skb_put_data(skb, x25->calluserdata.cuddata,
198 x25->calluserdata.cudlength);
199 x25->calluserdata.cudlength = 0;
200 break;
201
202 case X25_CALL_ACCEPTED:
203 dptr = skb_put(skb, 2);
204 *dptr++ = X25_CALL_ACCEPTED;
205 *dptr++ = 0x00; /* Address lengths */
206 len = x25_create_facilities(facilities,
207 &x25->facilities,
208 &x25->dte_facilities,
209 x25->vc_facil_mask);
210 skb_put_data(skb, facilities, len);
211
212 /* fast select with no restriction on response
213 allows call user data. Userland must
214 ensure it is ours and not theirs */
215 if(x25->facilities.reverse & 0x80) {
216 skb_put_data(skb,
217 x25->calluserdata.cuddata,
218 x25->calluserdata.cudlength);
219 }
220 x25->calluserdata.cudlength = 0;
221 break;
222
223 case X25_CLEAR_REQUEST:
224 dptr = skb_put(skb, 3);
225 *dptr++ = frametype;
226 *dptr++ = x25->causediag.cause;
227 *dptr++ = x25->causediag.diagnostic;
228 break;
229
230 case X25_RESET_REQUEST:
231 dptr = skb_put(skb, 3);
232 *dptr++ = frametype;
233 *dptr++ = 0x00; /* XXX */
234 *dptr++ = 0x00; /* XXX */
235 break;
236
237 case X25_RR:
238 case X25_RNR:
239 case X25_REJ:
240 if (x25->neighbour->extended) {
241 dptr = skb_put(skb, 2);
242 *dptr++ = frametype;
243 *dptr++ = (x25->vr << 1) & 0xFE;
244 } else {
245 dptr = skb_put(skb, 1);
246 *dptr = frametype;
247 *dptr++ |= (x25->vr << 5) & 0xE0;
248 }
249 break;
250
251 case X25_CLEAR_CONFIRMATION:
252 case X25_INTERRUPT_CONFIRMATION:
253 case X25_RESET_CONFIRMATION:
254 dptr = skb_put(skb, 1);
255 *dptr = frametype;
256 break;
257 }
258
259 x25_transmit_link(skb, x25->neighbour);
260 }
261
262 /*
263 * Unpick the contents of the passed X.25 Packet Layer frame.
264 */
x25_decode(struct sock * sk,struct sk_buff * skb,int * ns,int * nr,int * q,int * d,int * m)265 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
266 int *d, int *m)
267 {
268 struct x25_sock *x25 = x25_sk(sk);
269 unsigned char *frame;
270
271 if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
272 return X25_ILLEGAL;
273 frame = skb->data;
274
275 *ns = *nr = *q = *d = *m = 0;
276
277 switch (frame[2]) {
278 case X25_CALL_REQUEST:
279 case X25_CALL_ACCEPTED:
280 case X25_CLEAR_REQUEST:
281 case X25_CLEAR_CONFIRMATION:
282 case X25_INTERRUPT:
283 case X25_INTERRUPT_CONFIRMATION:
284 case X25_RESET_REQUEST:
285 case X25_RESET_CONFIRMATION:
286 case X25_RESTART_REQUEST:
287 case X25_RESTART_CONFIRMATION:
288 case X25_REGISTRATION_REQUEST:
289 case X25_REGISTRATION_CONFIRMATION:
290 case X25_DIAGNOSTIC:
291 return frame[2];
292 }
293
294 if (x25->neighbour->extended) {
295 if (frame[2] == X25_RR ||
296 frame[2] == X25_RNR ||
297 frame[2] == X25_REJ) {
298 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
299 return X25_ILLEGAL;
300 frame = skb->data;
301
302 *nr = (frame[3] >> 1) & 0x7F;
303 return frame[2];
304 }
305 } else {
306 if ((frame[2] & 0x1F) == X25_RR ||
307 (frame[2] & 0x1F) == X25_RNR ||
308 (frame[2] & 0x1F) == X25_REJ) {
309 *nr = (frame[2] >> 5) & 0x07;
310 return frame[2] & 0x1F;
311 }
312 }
313
314 if (x25->neighbour->extended) {
315 if ((frame[2] & 0x01) == X25_DATA) {
316 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
317 return X25_ILLEGAL;
318 frame = skb->data;
319
320 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
321 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
322 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
323 *nr = (frame[3] >> 1) & 0x7F;
324 *ns = (frame[2] >> 1) & 0x7F;
325 return X25_DATA;
326 }
327 } else {
328 if ((frame[2] & 0x01) == X25_DATA) {
329 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
330 *d = (frame[0] & X25_D_BIT) == X25_D_BIT;
331 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
332 *nr = (frame[2] >> 5) & 0x07;
333 *ns = (frame[2] >> 1) & 0x07;
334 return X25_DATA;
335 }
336 }
337
338 pr_debug("invalid PLP frame %3ph\n", frame);
339
340 return X25_ILLEGAL;
341 }
342
x25_disconnect(struct sock * sk,int reason,unsigned char cause,unsigned char diagnostic)343 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
344 unsigned char diagnostic)
345 {
346 struct x25_sock *x25 = x25_sk(sk);
347
348 x25_clear_queues(sk);
349 x25_stop_timer(sk);
350
351 x25->lci = 0;
352 x25->state = X25_STATE_0;
353
354 x25->causediag.cause = cause;
355 x25->causediag.diagnostic = diagnostic;
356
357 sk->sk_state = TCP_CLOSE;
358 sk->sk_err = reason;
359 sk->sk_shutdown |= SEND_SHUTDOWN;
360
361 if (!sock_flag(sk, SOCK_DEAD)) {
362 sk->sk_state_change(sk);
363 sock_set_flag(sk, SOCK_DEAD);
364 }
365 }
366
367 /*
368 * Clear an own-rx-busy condition and tell the peer about this, provided
369 * that there is a significant amount of free receive buffer space available.
370 */
x25_check_rbuf(struct sock * sk)371 void x25_check_rbuf(struct sock *sk)
372 {
373 struct x25_sock *x25 = x25_sk(sk);
374
375 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
376 (x25->condition & X25_COND_OWN_RX_BUSY)) {
377 x25->condition &= ~X25_COND_OWN_RX_BUSY;
378 x25->condition &= ~X25_COND_ACK_PENDING;
379 x25->vl = x25->vr;
380 x25_write_internal(sk, X25_RR);
381 x25_stop_timer(sk);
382 }
383 }
384
