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Linux/net/x25/x25_in.c

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  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 code.
 19  *                                        New timer architecture.
 20  *      2000-03-20      Daniela Squassoni Disabling/enabling of facilities
 21  *                                        negotiation.
 22  *      2000-11-10      Henner Eisen      Check and reset for out-of-sequence
 23  *                                        i-frames.
 24  */
 25 
 26 #define pr_fmt(fmt) "X25: " fmt
 27 
 28 #include <linux/slab.h>
 29 #include <linux/errno.h>
 30 #include <linux/kernel.h>
 31 #include <linux/string.h>
 32 #include <linux/skbuff.h>
 33 #include <net/sock.h>
 34 #include <net/tcp_states.h>
 35 #include <net/x25.h>
 36 
 37 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
 38 {
 39         struct sk_buff *skbo, *skbn = skb;
 40         struct x25_sock *x25 = x25_sk(sk);
 41 
 42         if (more) {
 43                 x25->fraglen += skb->len;
 44                 skb_queue_tail(&x25->fragment_queue, skb);
 45                 skb_set_owner_r(skb, sk);
 46                 return 0;
 47         }
 48 
 49         if (!more && x25->fraglen > 0) {        /* End of fragment */
 50                 int len = x25->fraglen + skb->len;
 51 
 52                 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
 53                         kfree_skb(skb);
 54                         return 1;
 55                 }
 56 
 57                 skb_queue_tail(&x25->fragment_queue, skb);
 58 
 59                 skb_reset_transport_header(skbn);
 60 
 61                 skbo = skb_dequeue(&x25->fragment_queue);
 62                 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
 63                                           skbo->len);
 64                 kfree_skb(skbo);
 65 
 66                 while ((skbo =
 67                         skb_dequeue(&x25->fragment_queue)) != NULL) {
 68                         skb_pull(skbo, (x25->neighbour->extended) ?
 69                                         X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
 70                         skb_copy_from_linear_data(skbo,
 71                                                   skb_put(skbn, skbo->len),
 72                                                   skbo->len);
 73                         kfree_skb(skbo);
 74                 }
 75 
 76                 x25->fraglen = 0;
 77         }
 78 
 79         skb_set_owner_r(skbn, sk);
 80         skb_queue_tail(&sk->sk_receive_queue, skbn);
 81         if (!sock_flag(sk, SOCK_DEAD))
 82                 sk->sk_data_ready(sk);
 83 
 84         return 0;
 85 }
 86 
 87 /*
 88  * State machine for state 1, Awaiting Call Accepted State.
 89  * The handling of the timer(s) is in file x25_timer.c.
 90  * Handling of state 0 and connection release is in af_x25.c.
 91  */
 92 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 93 {
 94         struct x25_address source_addr, dest_addr;
 95         int len;
 96         struct x25_sock *x25 = x25_sk(sk);
 97 
 98         switch (frametype) {
 99         case X25_CALL_ACCEPTED: {
100 
101                 x25_stop_timer(sk);
102                 x25->condition = 0x00;
103                 x25->vs        = 0;
104                 x25->va        = 0;
105                 x25->vr        = 0;
106                 x25->vl        = 0;
107                 x25->state     = X25_STATE_3;
108                 sk->sk_state   = TCP_ESTABLISHED;
109                 /*
110                  *      Parse the data in the frame.
111                  */
112                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
113                         goto out_clear;
114                 skb_pull(skb, X25_STD_MIN_LEN);
115 
116                 len = x25_parse_address_block(skb, &source_addr,
117                                               &dest_addr);
118                 if (len > 0)
119                         skb_pull(skb, len);
120                 else if (len < 0)
121                         goto out_clear;
122 
123                 len = x25_parse_facilities(skb, &x25->facilities,
124                                            &x25->dte_facilities,
125                                            &x25->vc_facil_mask);
126                 if (len > 0)
127                         skb_pull(skb, len);
128                 else if (len < 0)
129                         goto out_clear;
130                 /*
131                  *      Copy any Call User Data.
132                  */
133                 if (skb->len > 0) {
134                         if (skb->len > X25_MAX_CUD_LEN)
135                                 goto out_clear;
136 
137                         skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
138                                 skb->len);
139                         x25->calluserdata.cudlength = skb->len;
140                 }
141                 if (!sock_flag(sk, SOCK_DEAD))
142                         sk->sk_state_change(sk);
143                 break;
144         }
145         case X25_CLEAR_REQUEST:
146                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
147                         goto out_clear;
148 
149                 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
150                 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
151                 break;
152 
153         default:
154                 break;
155         }
156 
157         return 0;
158 
159 out_clear:
160         x25_write_internal(sk, X25_CLEAR_REQUEST);
161         x25->state = X25_STATE_2;
162         x25_start_t23timer(sk);
163         return 0;
164 }
165 
166 /*
167  * State machine for state 2, Awaiting Clear Confirmation State.
168  * The handling of the timer(s) is in file x25_timer.c
169  * Handling of state 0 and connection release is in af_x25.c.
170  */
171 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
172 {
173         switch (frametype) {
174 
175                 case X25_CLEAR_REQUEST:
176                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
177                                 goto out_clear;
178 
179                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
180                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
181                         break;
182 
183                 case X25_CLEAR_CONFIRMATION:
184                         x25_disconnect(sk, 0, 0, 0);
185                         break;
186 
187                 default:
188                         break;
189         }
190 
191         return 0;
192 
193 out_clear:
194         x25_write_internal(sk, X25_CLEAR_REQUEST);
195         x25_start_t23timer(sk);
196         return 0;
197 }
198 
199 /*
200  * State machine for state 3, Connected State.
201  * The handling of the timer(s) is in file x25_timer.c
202  * Handling of state 0 and connection release is in af_x25.c.
203  */
204 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
205 {
206         int queued = 0;
207         int modulus;
208         struct x25_sock *x25 = x25_sk(sk);
209 
210         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
211 
212         switch (frametype) {
213 
214                 case X25_RESET_REQUEST:
215                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
216                         x25_stop_timer(sk);
217                         x25->condition = 0x00;
218                         x25->vs        = 0;
219                         x25->vr        = 0;
220                         x25->va        = 0;
221                         x25->vl        = 0;
222                         x25_requeue_frames(sk);
223                         break;
224 
225                 case X25_CLEAR_REQUEST:
226                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
227                                 goto out_clear;
228 
229                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
230                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
231                         break;
232 
233                 case X25_RR:
234                 case X25_RNR:
235                         if (!x25_validate_nr(sk, nr)) {
236                                 x25_clear_queues(sk);
237                                 x25_write_internal(sk, X25_RESET_REQUEST);
238                                 x25_start_t22timer(sk);
239                                 x25->condition = 0x00;
240                                 x25->vs        = 0;
241                                 x25->vr        = 0;
242                                 x25->va        = 0;
243                                 x25->vl        = 0;
244                                 x25->state     = X25_STATE_4;
245                         } else {
246                                 x25_frames_acked(sk, nr);
247                                 if (frametype == X25_RNR) {
248                                         x25->condition |= X25_COND_PEER_RX_BUSY;
249                                 } else {
250                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
251                                 }
252                         }
253                         break;
254 
255                 case X25_DATA:  /* XXX */
256                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
257                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
258                                 x25_clear_queues(sk);
259                                 x25_write_internal(sk, X25_RESET_REQUEST);
260                                 x25_start_t22timer(sk);
261                                 x25->condition = 0x00;
262                                 x25->vs        = 0;
263                                 x25->vr        = 0;
264                                 x25->va        = 0;
265                                 x25->vl        = 0;
266                                 x25->state     = X25_STATE_4;
267                                 break;
268                         }
269                         x25_frames_acked(sk, nr);
270                         if (ns == x25->vr) {
271                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
272                                         x25->vr = (x25->vr + 1) % modulus;
273                                         queued = 1;
274                                 } else {
275                                         /* Should never happen */
276                                         x25_clear_queues(sk);
277                                         x25_write_internal(sk, X25_RESET_REQUEST);
278                                         x25_start_t22timer(sk);
279                                         x25->condition = 0x00;
280                                         x25->vs        = 0;
281                                         x25->vr        = 0;
282                                         x25->va        = 0;
283                                         x25->vl        = 0;
284                                         x25->state     = X25_STATE_4;
285                                         break;
286                                 }
287                                 if (atomic_read(&sk->sk_rmem_alloc) >
288                                     (sk->sk_rcvbuf >> 1))
289                                         x25->condition |= X25_COND_OWN_RX_BUSY;
290                         }
291                         /*
292                          *      If the window is full Ack it immediately, else
293                          *      start the holdback timer.
294                          */
295                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
296                                 x25->condition &= ~X25_COND_ACK_PENDING;
297                                 x25_stop_timer(sk);
298                                 x25_enquiry_response(sk);
299                         } else {
300                                 x25->condition |= X25_COND_ACK_PENDING;
301                                 x25_start_t2timer(sk);
302                         }
303                         break;
304 
305                 case X25_INTERRUPT_CONFIRMATION:
306                         clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
307                         break;
308 
309                 case X25_INTERRUPT:
310                         if (sock_flag(sk, SOCK_URGINLINE))
311                                 queued = !sock_queue_rcv_skb(sk, skb);
312                         else {
313                                 skb_set_owner_r(skb, sk);
314                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
315                                 queued = 1;
316                         }
317                         sk_send_sigurg(sk);
318                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
319                         break;
320 
321                 default:
322                         pr_warn("unknown %02X in state 3\n", frametype);
323                         break;
324         }
325 
326         return queued;
327 
328 out_clear:
329         x25_write_internal(sk, X25_CLEAR_REQUEST);
330         x25->state = X25_STATE_2;
331         x25_start_t23timer(sk);
332         return 0;
333 }
334 
335 /*
336  * State machine for state 4, Awaiting Reset Confirmation State.
337  * The handling of the timer(s) is in file x25_timer.c
338  * Handling of state 0 and connection release is in af_x25.c.
339  */
340 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
341 {
342         struct x25_sock *x25 = x25_sk(sk);
343 
344         switch (frametype) {
345 
346                 case X25_RESET_REQUEST:
347                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
348                 case X25_RESET_CONFIRMATION: {
349                         x25_stop_timer(sk);
350                         x25->condition = 0x00;
351                         x25->va        = 0;
352                         x25->vr        = 0;
353                         x25->vs        = 0;
354                         x25->vl        = 0;
355                         x25->state     = X25_STATE_3;
356                         x25_requeue_frames(sk);
357                         break;
358                 }
359                 case X25_CLEAR_REQUEST:
360                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
361                                 goto out_clear;
362 
363                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
364                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
365                         break;
366 
367                 default:
368                         break;
369         }
370 
371         return 0;
372 
373 out_clear:
374         x25_write_internal(sk, X25_CLEAR_REQUEST);
375         x25->state = X25_STATE_2;
376         x25_start_t23timer(sk);
377         return 0;
378 }
379 
380 /* Higher level upcall for a LAPB frame */
381 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
382 {
383         struct x25_sock *x25 = x25_sk(sk);
384         int queued = 0, frametype, ns, nr, q, d, m;
385 
386         if (x25->state == X25_STATE_0)
387                 return 0;
388 
389         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
390 
391         switch (x25->state) {
392         case X25_STATE_1:
393                 queued = x25_state1_machine(sk, skb, frametype);
394                 break;
395         case X25_STATE_2:
396                 queued = x25_state2_machine(sk, skb, frametype);
397                 break;
398         case X25_STATE_3:
399                 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
400                 break;
401         case X25_STATE_4:
402                 queued = x25_state4_machine(sk, skb, frametype);
403                 break;
404         }
405 
406         x25_kick(sk);
407 
408         return queued;
409 }
410 
411 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
412 {
413         int queued = x25_process_rx_frame(sk, skb);
414 
415         if (!queued)
416                 kfree_skb(skb);
417 
418         return 0;
419 }
420 

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