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Linux/net/decnet/dn_nsp_in.c

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  1 /*
  2  * DECnet       An implementation of the DECnet protocol suite for the LINUX
  3  *              operating system.  DECnet is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              DECnet Network Services Protocol (Input)
  7  *
  8  * Author:      Eduardo Marcelo Serrat <emserrat@geocities.com>
  9  *
 10  * Changes:
 11  *
 12  *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
 13  *                       original dn_nsp.c.
 14  *    Steve Whitehouse:  Updated to work with my new routing architecture.
 15  *    Steve Whitehouse:  Add changes from Eduardo Serrat's patches.
 16  *    Steve Whitehouse:  Put all ack handling code in a common routine.
 17  *    Steve Whitehouse:  Put other common bits into dn_nsp_rx()
 18  *    Steve Whitehouse:  More checks on skb->len to catch bogus packets
 19  *                       Fixed various race conditions and possible nasties.
 20  *    Steve Whitehouse:  Now handles returned conninit frames.
 21  *     David S. Miller:  New socket locking
 22  *    Steve Whitehouse:  Fixed lockup when socket filtering was enabled.
 23  *         Paul Koning:  Fix to push CC sockets into RUN when acks are
 24  *                       received.
 25  *    Steve Whitehouse:
 26  *   Patrick Caulfield:  Checking conninits for correctness & sending of error
 27  *                       responses.
 28  *    Steve Whitehouse:  Added backlog congestion level return codes.
 29  *   Patrick Caulfield:
 30  *    Steve Whitehouse:  Added flow control support (outbound)
 31  *    Steve Whitehouse:  Prepare for nonlinear skbs
 32  */
 33 
 34 /******************************************************************************
 35     (c) 1995-1998 E.M. Serrat           emserrat@geocities.com
 36 
 37     This program is free software; you can redistribute it and/or modify
 38     it under the terms of the GNU General Public License as published by
 39     the Free Software Foundation; either version 2 of the License, or
 40     any later version.
 41 
 42     This program is distributed in the hope that it will be useful,
 43     but WITHOUT ANY WARRANTY; without even the implied warranty of
 44     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 45     GNU General Public License for more details.
 46 *******************************************************************************/
 47 
 48 #include <linux/errno.h>
 49 #include <linux/types.h>
 50 #include <linux/socket.h>
 51 #include <linux/in.h>
 52 #include <linux/kernel.h>
 53 #include <linux/timer.h>
 54 #include <linux/string.h>
 55 #include <linux/sockios.h>
 56 #include <linux/net.h>
 57 #include <linux/netdevice.h>
 58 #include <linux/inet.h>
 59 #include <linux/route.h>
 60 #include <linux/slab.h>
 61 #include <net/sock.h>
 62 #include <net/tcp_states.h>
 63 #include <linux/fcntl.h>
 64 #include <linux/mm.h>
 65 #include <linux/termios.h>
 66 #include <linux/interrupt.h>
 67 #include <linux/proc_fs.h>
 68 #include <linux/stat.h>
 69 #include <linux/init.h>
 70 #include <linux/poll.h>
 71 #include <linux/netfilter_decnet.h>
 72 #include <net/neighbour.h>
 73 #include <net/dst.h>
 74 #include <net/dn.h>
 75 #include <net/dn_nsp.h>
 76 #include <net/dn_dev.h>
 77 #include <net/dn_route.h>
 78 
 79 extern int decnet_log_martians;
 80 
 81 static void dn_log_martian(struct sk_buff *skb, const char *msg)
 82 {
 83         if (decnet_log_martians) {
 84                 char *devname = skb->dev ? skb->dev->name : "???";
 85                 struct dn_skb_cb *cb = DN_SKB_CB(skb);
 86                 net_info_ratelimited("DECnet: Martian packet (%s) dev=%s src=0x%04hx dst=0x%04hx srcport=0x%04hx dstport=0x%04hx\n",
 87                                      msg, devname,
 88                                      le16_to_cpu(cb->src),
 89                                      le16_to_cpu(cb->dst),
 90                                      le16_to_cpu(cb->src_port),
 91                                      le16_to_cpu(cb->dst_port));
 92         }
 93 }
 94 
 95 /*
 96  * For this function we've flipped the cross-subchannel bit
 97  * if the message is an otherdata or linkservice message. Thus
 98  * we can use it to work out what to update.
 99  */
100 static void dn_ack(struct sock *sk, struct sk_buff *skb, unsigned short ack)
101 {
102         struct dn_scp *scp = DN_SK(sk);
103         unsigned short type = ((ack >> 12) & 0x0003);
104         int wakeup = 0;
105 
106         switch (type) {
107         case 0: /* ACK - Data */
108                 if (dn_after(ack, scp->ackrcv_dat)) {
109                         scp->ackrcv_dat = ack & 0x0fff;
110                         wakeup |= dn_nsp_check_xmit_queue(sk, skb,
111                                                           &scp->data_xmit_queue,
112                                                           ack);
113                 }
114                 break;
115         case 1: /* NAK - Data */
116                 break;
117         case 2: /* ACK - OtherData */
118                 if (dn_after(ack, scp->ackrcv_oth)) {
119                         scp->ackrcv_oth = ack & 0x0fff;
120                         wakeup |= dn_nsp_check_xmit_queue(sk, skb,
121                                                           &scp->other_xmit_queue,
122                                                           ack);
123                 }
124                 break;
125         case 3: /* NAK - OtherData */
126                 break;
127         }
128 
129         if (wakeup && !sock_flag(sk, SOCK_DEAD))
130                 sk->sk_state_change(sk);
131 }
132 
133 /*
134  * This function is a universal ack processor.
135  */
136 static int dn_process_ack(struct sock *sk, struct sk_buff *skb, int oth)
137 {
138         __le16 *ptr = (__le16 *)skb->data;
139         int len = 0;
140         unsigned short ack;
141 
142         if (skb->len < 2)
143                 return len;
144 
145         if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
146                 skb_pull(skb, 2);
147                 ptr++;
148                 len += 2;
149                 if ((ack & 0x4000) == 0) {
150                         if (oth)
151                                 ack ^= 0x2000;
152                         dn_ack(sk, skb, ack);
153                 }
154         }
155 
156         if (skb->len < 2)
157                 return len;
158 
159         if ((ack = le16_to_cpu(*ptr)) & 0x8000) {
160                 skb_pull(skb, 2);
161                 len += 2;
162                 if ((ack & 0x4000) == 0) {
163                         if (oth)
164                                 ack ^= 0x2000;
165                         dn_ack(sk, skb, ack);
166                 }
167         }
168 
169         return len;
170 }
171 
172 
173 /**
174  * dn_check_idf - Check an image data field format is correct.
175  * @pptr: Pointer to pointer to image data
176  * @len: Pointer to length of image data
177  * @max: The maximum allowed length of the data in the image data field
178  * @follow_on: Check that this many bytes exist beyond the end of the image data
179  *
180  * Returns: 0 if ok, -1 on error
181  */
182 static inline int dn_check_idf(unsigned char **pptr, int *len, unsigned char max, unsigned char follow_on)
183 {
184         unsigned char *ptr = *pptr;
185         unsigned char flen = *ptr++;
186 
187         (*len)--;
188         if (flen > max)
189                 return -1;
190         if ((flen + follow_on) > *len)
191                 return -1;
192 
193         *len -= flen;
194         *pptr = ptr + flen;
195         return 0;
196 }
197 
198 /*
199  * Table of reason codes to pass back to node which sent us a badly
200  * formed message, plus text messages for the log. A zero entry in
201  * the reason field means "don't reply" otherwise a disc init is sent with
202  * the specified reason code.
203  */
204 static struct {
205         unsigned short reason;
206         const char *text;
207 } ci_err_table[] = {
208  { 0,             "CI: Truncated message" },
209  { NSP_REASON_ID, "CI: Destination username error" },
210  { NSP_REASON_ID, "CI: Destination username type" },
211  { NSP_REASON_US, "CI: Source username error" },
212  { 0,             "CI: Truncated at menuver" },
213  { 0,             "CI: Truncated before access or user data" },
214  { NSP_REASON_IO, "CI: Access data format error" },
215  { NSP_REASON_IO, "CI: User data format error" }
216 };
217 
218 /*
219  * This function uses a slightly different lookup method
220  * to find its sockets, since it searches on object name/number
221  * rather than port numbers. Various tests are done to ensure that
222  * the incoming data is in the correct format before it is queued to
223  * a socket.
224  */
225 static struct sock *dn_find_listener(struct sk_buff *skb, unsigned short *reason)
226 {
227         struct dn_skb_cb *cb = DN_SKB_CB(skb);
228         struct nsp_conn_init_msg *msg = (struct nsp_conn_init_msg *)skb->data;
229         struct sockaddr_dn dstaddr;
230         struct sockaddr_dn srcaddr;
231         unsigned char type = 0;
232         int dstlen;
233         int srclen;
234         unsigned char *ptr;
235         int len;
236         int err = 0;
237         unsigned char menuver;
238 
239         memset(&dstaddr, 0, sizeof(struct sockaddr_dn));
240         memset(&srcaddr, 0, sizeof(struct sockaddr_dn));
241 
242         /*
243          * 1. Decode & remove message header
244          */
245         cb->src_port = msg->srcaddr;
246         cb->dst_port = msg->dstaddr;
247         cb->services = msg->services;
248         cb->info     = msg->info;
249         cb->segsize  = le16_to_cpu(msg->segsize);
250 
251         if (!pskb_may_pull(skb, sizeof(*msg)))
252                 goto err_out;
253 
254         skb_pull(skb, sizeof(*msg));
255 
256         len = skb->len;
257         ptr = skb->data;
258 
259         /*
260          * 2. Check destination end username format
261          */
262         dstlen = dn_username2sockaddr(ptr, len, &dstaddr, &type);
263         err++;
264         if (dstlen < 0)
265                 goto err_out;
266 
267         err++;
268         if (type > 1)
269                 goto err_out;
270 
271         len -= dstlen;
272         ptr += dstlen;
273 
274         /*
275          * 3. Check source end username format
276          */
277         srclen = dn_username2sockaddr(ptr, len, &srcaddr, &type);
278         err++;
279         if (srclen < 0)
280                 goto err_out;
281 
282         len -= srclen;
283         ptr += srclen;
284         err++;
285         if (len < 1)
286                 goto err_out;
287 
288         menuver = *ptr;
289         ptr++;
290         len--;
291 
292         /*
293          * 4. Check that optional data actually exists if menuver says it does
294          */
295         err++;
296         if ((menuver & (DN_MENUVER_ACC | DN_MENUVER_USR)) && (len < 1))
297                 goto err_out;
298 
299         /*
300          * 5. Check optional access data format
301          */
302         err++;
303         if (menuver & DN_MENUVER_ACC) {
304                 if (dn_check_idf(&ptr, &len, 39, 1))
305                         goto err_out;
306                 if (dn_check_idf(&ptr, &len, 39, 1))
307                         goto err_out;
308                 if (dn_check_idf(&ptr, &len, 39, (menuver & DN_MENUVER_USR) ? 1 : 0))
309                         goto err_out;
310         }
311 
312         /*
313          * 6. Check optional user data format
314          */
315         err++;
316         if (menuver & DN_MENUVER_USR) {
317                 if (dn_check_idf(&ptr, &len, 16, 0))
318                         goto err_out;
319         }
320 
321         /*
322          * 7. Look up socket based on destination end username
323          */
324         return dn_sklist_find_listener(&dstaddr);
325 err_out:
326         dn_log_martian(skb, ci_err_table[err].text);
327         *reason = ci_err_table[err].reason;
328         return NULL;
329 }
330 
331 
332 static void dn_nsp_conn_init(struct sock *sk, struct sk_buff *skb)
333 {
334         if (sk_acceptq_is_full(sk)) {
335                 kfree_skb(skb);
336                 return;
337         }
338 
339         sk->sk_ack_backlog++;
340         skb_queue_tail(&sk->sk_receive_queue, skb);
341         sk->sk_state_change(sk);
342 }
343 
344 static void dn_nsp_conn_conf(struct sock *sk, struct sk_buff *skb)
345 {
346         struct dn_skb_cb *cb = DN_SKB_CB(skb);
347         struct dn_scp *scp = DN_SK(sk);
348         unsigned char *ptr;
349 
350         if (skb->len < 4)
351                 goto out;
352 
353         ptr = skb->data;
354         cb->services = *ptr++;
355         cb->info = *ptr++;
356         cb->segsize = le16_to_cpu(*(__le16 *)ptr);
357 
358         if ((scp->state == DN_CI) || (scp->state == DN_CD)) {
359                 scp->persist = 0;
360                 scp->addrrem = cb->src_port;
361                 sk->sk_state = TCP_ESTABLISHED;
362                 scp->state = DN_RUN;
363                 scp->services_rem = cb->services;
364                 scp->info_rem = cb->info;
365                 scp->segsize_rem = cb->segsize;
366 
367                 if ((scp->services_rem & NSP_FC_MASK) == NSP_FC_NONE)
368                         scp->max_window = decnet_no_fc_max_cwnd;
369 
370                 if (skb->len > 0) {
371                         u16 dlen = *skb->data;
372                         if ((dlen <= 16) && (dlen <= skb->len)) {
373                                 scp->conndata_in.opt_optl = cpu_to_le16(dlen);
374                                 skb_copy_from_linear_data_offset(skb, 1,
375                                               scp->conndata_in.opt_data, dlen);
376                         }
377                 }
378                 dn_nsp_send_link(sk, DN_NOCHANGE, 0);
379                 if (!sock_flag(sk, SOCK_DEAD))
380                         sk->sk_state_change(sk);
381         }
382 
383 out:
384         kfree_skb(skb);
385 }
386 
387 static void dn_nsp_conn_ack(struct sock *sk, struct sk_buff *skb)
388 {
389         struct dn_scp *scp = DN_SK(sk);
390 
391         if (scp->state == DN_CI) {
392                 scp->state = DN_CD;
393                 scp->persist = 0;
394         }
395 
396         kfree_skb(skb);
397 }
398 
399 static void dn_nsp_disc_init(struct sock *sk, struct sk_buff *skb)
400 {
401         struct dn_scp *scp = DN_SK(sk);
402         struct dn_skb_cb *cb = DN_SKB_CB(skb);
403         unsigned short reason;
404 
405         if (skb->len < 2)
406                 goto out;
407 
408         reason = le16_to_cpu(*(__le16 *)skb->data);
409         skb_pull(skb, 2);
410 
411         scp->discdata_in.opt_status = cpu_to_le16(reason);
412         scp->discdata_in.opt_optl   = 0;
413         memset(scp->discdata_in.opt_data, 0, 16);
414 
415         if (skb->len > 0) {
416                 u16 dlen = *skb->data;
417                 if ((dlen <= 16) && (dlen <= skb->len)) {
418                         scp->discdata_in.opt_optl = cpu_to_le16(dlen);
419                         skb_copy_from_linear_data_offset(skb, 1, scp->discdata_in.opt_data, dlen);
420                 }
421         }
422 
423         scp->addrrem = cb->src_port;
424         sk->sk_state = TCP_CLOSE;
425 
426         switch (scp->state) {
427         case DN_CI:
428         case DN_CD:
429                 scp->state = DN_RJ;
430                 sk->sk_err = ECONNREFUSED;
431                 break;
432         case DN_RUN:
433                 sk->sk_shutdown |= SHUTDOWN_MASK;
434                 scp->state = DN_DN;
435                 break;
436         case DN_DI:
437                 scp->state = DN_DIC;
438                 break;
439         }
440 
441         if (!sock_flag(sk, SOCK_DEAD)) {
442                 if (sk->sk_socket->state != SS_UNCONNECTED)
443                         sk->sk_socket->state = SS_DISCONNECTING;
444                 sk->sk_state_change(sk);
445         }
446 
447         /*
448          * It appears that its possible for remote machines to send disc
449          * init messages with no port identifier if we are in the CI and
450          * possibly also the CD state. Obviously we shouldn't reply with
451          * a message if we don't know what the end point is.
452          */
453         if (scp->addrrem) {
454                 dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC, GFP_ATOMIC);
455         }
456         scp->persist_fxn = dn_destroy_timer;
457         scp->persist = dn_nsp_persist(sk);
458 
459 out:
460         kfree_skb(skb);
461 }
462 
463 /*
464  * disc_conf messages are also called no_resources or no_link
465  * messages depending upon the "reason" field.
466  */
467 static void dn_nsp_disc_conf(struct sock *sk, struct sk_buff *skb)
468 {
469         struct dn_scp *scp = DN_SK(sk);
470         unsigned short reason;
471 
472         if (skb->len != 2)
473                 goto out;
474 
475         reason = le16_to_cpu(*(__le16 *)skb->data);
476 
477         sk->sk_state = TCP_CLOSE;
478 
479         switch (scp->state) {
480         case DN_CI:
481                 scp->state = DN_NR;
482                 break;
483         case DN_DR:
484                 if (reason == NSP_REASON_DC)
485                         scp->state = DN_DRC;
486                 if (reason == NSP_REASON_NL)
487                         scp->state = DN_CN;
488                 break;
489         case DN_DI:
490                 scp->state = DN_DIC;
491                 break;
492         case DN_RUN:
493                 sk->sk_shutdown |= SHUTDOWN_MASK;
494         case DN_CC:
495                 scp->state = DN_CN;
496         }
497 
498         if (!sock_flag(sk, SOCK_DEAD)) {
499                 if (sk->sk_socket->state != SS_UNCONNECTED)
500                         sk->sk_socket->state = SS_DISCONNECTING;
501                 sk->sk_state_change(sk);
502         }
503 
504         scp->persist_fxn = dn_destroy_timer;
505         scp->persist = dn_nsp_persist(sk);
506 
507 out:
508         kfree_skb(skb);
509 }
510 
511 static void dn_nsp_linkservice(struct sock *sk, struct sk_buff *skb)
512 {
513         struct dn_scp *scp = DN_SK(sk);
514         unsigned short segnum;
515         unsigned char lsflags;
516         signed char fcval;
517         int wake_up = 0;
518         char *ptr = skb->data;
519         unsigned char fctype = scp->services_rem & NSP_FC_MASK;
520 
521         if (skb->len != 4)
522                 goto out;
523 
524         segnum = le16_to_cpu(*(__le16 *)ptr);
525         ptr += 2;
526         lsflags = *(unsigned char *)ptr++;
527         fcval = *ptr;
528 
529         /*
530          * Here we ignore erronous packets which should really
531          * should cause a connection abort. It is not critical
532          * for now though.
533          */
534         if (lsflags & 0xf8)
535                 goto out;
536 
537         if (seq_next(scp->numoth_rcv, segnum)) {
538                 seq_add(&scp->numoth_rcv, 1);
539                 switch(lsflags & 0x04) { /* FCVAL INT */
540                 case 0x00: /* Normal Request */
541                         switch(lsflags & 0x03) { /* FCVAL MOD */
542                         case 0x00: /* Request count */
543                                 if (fcval < 0) {
544                                         unsigned char p_fcval = -fcval;
545                                         if ((scp->flowrem_dat > p_fcval) &&
546                                             (fctype == NSP_FC_SCMC)) {
547                                                 scp->flowrem_dat -= p_fcval;
548                                         }
549                                 } else if (fcval > 0) {
550                                         scp->flowrem_dat += fcval;
551                                         wake_up = 1;
552                                 }
553                                 break;
554                         case 0x01: /* Stop outgoing data */
555                                 scp->flowrem_sw = DN_DONTSEND;
556                                 break;
557                         case 0x02: /* Ok to start again */
558                                 scp->flowrem_sw = DN_SEND;
559                                 dn_nsp_output(sk);
560                                 wake_up = 1;
561                         }
562                         break;
563                 case 0x04: /* Interrupt Request */
564                         if (fcval > 0) {
565                                 scp->flowrem_oth += fcval;
566                                 wake_up = 1;
567                         }
568                         break;
569                 }
570                 if (wake_up && !sock_flag(sk, SOCK_DEAD))
571                         sk->sk_state_change(sk);
572         }
573 
574         dn_nsp_send_oth_ack(sk);
575 
576 out:
577         kfree_skb(skb);
578 }
579 
580 /*
581  * Copy of sock_queue_rcv_skb (from sock.h) without
582  * bh_lock_sock() (its already held when this is called) which
583  * also allows data and other data to be queued to a socket.
584  */
585 static __inline__ int dn_queue_skb(struct sock *sk, struct sk_buff *skb, int sig, struct sk_buff_head *queue)
586 {
587         int err;
588 
589         /* Cast skb->rcvbuf to unsigned... It's pointless, but reduces
590            number of warnings when compiling with -W --ANK
591          */
592         if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
593             (unsigned int)sk->sk_rcvbuf) {
594                 err = -ENOMEM;
595                 goto out;
596         }
597 
598         err = sk_filter(sk, skb);
599         if (err)
600                 goto out;
601 
602         skb_set_owner_r(skb, sk);
603         skb_queue_tail(queue, skb);
604 
605         if (!sock_flag(sk, SOCK_DEAD))
606                 sk->sk_data_ready(sk);
607 out:
608         return err;
609 }
610 
611 static void dn_nsp_otherdata(struct sock *sk, struct sk_buff *skb)
612 {
613         struct dn_scp *scp = DN_SK(sk);
614         unsigned short segnum;
615         struct dn_skb_cb *cb = DN_SKB_CB(skb);
616         int queued = 0;
617 
618         if (skb->len < 2)
619                 goto out;
620 
621         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
622         skb_pull(skb, 2);
623 
624         if (seq_next(scp->numoth_rcv, segnum)) {
625 
626                 if (dn_queue_skb(sk, skb, SIGURG, &scp->other_receive_queue) == 0) {
627                         seq_add(&scp->numoth_rcv, 1);
628                         scp->other_report = 0;
629                         queued = 1;
630                 }
631         }
632 
633         dn_nsp_send_oth_ack(sk);
634 out:
635         if (!queued)
636                 kfree_skb(skb);
637 }
638 
639 static void dn_nsp_data(struct sock *sk, struct sk_buff *skb)
640 {
641         int queued = 0;
642         unsigned short segnum;
643         struct dn_skb_cb *cb = DN_SKB_CB(skb);
644         struct dn_scp *scp = DN_SK(sk);
645 
646         if (skb->len < 2)
647                 goto out;
648 
649         cb->segnum = segnum = le16_to_cpu(*(__le16 *)skb->data);
650         skb_pull(skb, 2);
651 
652         if (seq_next(scp->numdat_rcv, segnum)) {
653                 if (dn_queue_skb(sk, skb, SIGIO, &sk->sk_receive_queue) == 0) {
654                         seq_add(&scp->numdat_rcv, 1);
655                         queued = 1;
656                 }
657 
658                 if ((scp->flowloc_sw == DN_SEND) && dn_congested(sk)) {
659                         scp->flowloc_sw = DN_DONTSEND;
660                         dn_nsp_send_link(sk, DN_DONTSEND, 0);
661                 }
662         }
663 
664         dn_nsp_send_data_ack(sk);
665 out:
666         if (!queued)
667                 kfree_skb(skb);
668 }
669 
670 /*
671  * If one of our conninit messages is returned, this function
672  * deals with it. It puts the socket into the NO_COMMUNICATION
673  * state.
674  */
675 static void dn_returned_conn_init(struct sock *sk, struct sk_buff *skb)
676 {
677         struct dn_scp *scp = DN_SK(sk);
678 
679         if (scp->state == DN_CI) {
680                 scp->state = DN_NC;
681                 sk->sk_state = TCP_CLOSE;
682                 if (!sock_flag(sk, SOCK_DEAD))
683                         sk->sk_state_change(sk);
684         }
685 
686         kfree_skb(skb);
687 }
688 
689 static int dn_nsp_no_socket(struct sk_buff *skb, unsigned short reason)
690 {
691         struct dn_skb_cb *cb = DN_SKB_CB(skb);
692         int ret = NET_RX_DROP;
693 
694         /* Must not reply to returned packets */
695         if (cb->rt_flags & DN_RT_F_RTS)
696                 goto out;
697 
698         if ((reason != NSP_REASON_OK) && ((cb->nsp_flags & 0x0c) == 0x08)) {
699                 switch (cb->nsp_flags & 0x70) {
700                 case 0x10:
701                 case 0x60: /* (Retransmitted) Connect Init */
702                         dn_nsp_return_disc(skb, NSP_DISCINIT, reason);
703                         ret = NET_RX_SUCCESS;
704                         break;
705                 case 0x20: /* Connect Confirm */
706                         dn_nsp_return_disc(skb, NSP_DISCCONF, reason);
707                         ret = NET_RX_SUCCESS;
708                         break;
709                 }
710         }
711 
712 out:
713         kfree_skb(skb);
714         return ret;
715 }
716 
717 static int dn_nsp_rx_packet(struct net *net, struct sock *sk2,
718                             struct sk_buff *skb)
719 {
720         struct dn_skb_cb *cb = DN_SKB_CB(skb);
721         struct sock *sk = NULL;
722         unsigned char *ptr = (unsigned char *)skb->data;
723         unsigned short reason = NSP_REASON_NL;
724 
725         if (!pskb_may_pull(skb, 2))
726                 goto free_out;
727 
728         skb_reset_transport_header(skb);
729         cb->nsp_flags = *ptr++;
730 
731         if (decnet_debug_level & 2)
732                 printk(KERN_DEBUG "dn_nsp_rx: Message type 0x%02x\n", (int)cb->nsp_flags);
733 
734         if (cb->nsp_flags & 0x83)
735                 goto free_out;
736 
737         /*
738          * Filter out conninits and useless packet types
739          */
740         if ((cb->nsp_flags & 0x0c) == 0x08) {
741                 switch (cb->nsp_flags & 0x70) {
742                 case 0x00: /* NOP */
743                 case 0x70: /* Reserved */
744                 case 0x50: /* Reserved, Phase II node init */
745                         goto free_out;
746                 case 0x10:
747                 case 0x60:
748                         if (unlikely(cb->rt_flags & DN_RT_F_RTS))
749                                 goto free_out;
750                         sk = dn_find_listener(skb, &reason);
751                         goto got_it;
752                 }
753         }
754 
755         if (!pskb_may_pull(skb, 3))
756                 goto free_out;
757 
758         /*
759          * Grab the destination address.
760          */
761         cb->dst_port = *(__le16 *)ptr;
762         cb->src_port = 0;
763         ptr += 2;
764 
765         /*
766          * If not a connack, grab the source address too.
767          */
768         if (pskb_may_pull(skb, 5)) {
769                 cb->src_port = *(__le16 *)ptr;
770                 ptr += 2;
771                 skb_pull(skb, 5);
772         }
773 
774         /*
775          * Returned packets...
776          * Swap src & dst and look up in the normal way.
777          */
778         if (unlikely(cb->rt_flags & DN_RT_F_RTS)) {
779                 swap(cb->dst_port, cb->src_port);
780                 swap(cb->dst, cb->src);
781         }
782 
783         /*
784          * Find the socket to which this skb is destined.
785          */
786         sk = dn_find_by_skb(skb);
787 got_it:
788         if (sk != NULL) {
789                 struct dn_scp *scp = DN_SK(sk);
790 
791                 /* Reset backoff */
792                 scp->nsp_rxtshift = 0;
793 
794                 /*
795                  * We linearize everything except data segments here.
796                  */
797                 if (cb->nsp_flags & ~0x60) {
798                         if (unlikely(skb_linearize(skb)))
799                                 goto free_out;
800                 }
801 
802                 return sk_receive_skb(sk, skb, 0);
803         }
804 
805         return dn_nsp_no_socket(skb, reason);
806 
807 free_out:
808         kfree_skb(skb);
809         return NET_RX_DROP;
810 }
811 
812 int dn_nsp_rx(struct sk_buff *skb)
813 {
814         return NF_HOOK(NFPROTO_DECNET, NF_DN_LOCAL_IN,
815                        &init_net, NULL, skb, skb->dev, NULL,
816                        dn_nsp_rx_packet);
817 }
818 
819 /*
820  * This is the main receive routine for sockets. It is called
821  * from the above when the socket is not busy, and also from
822  * sock_release() when there is a backlog queued up.
823  */
824 int dn_nsp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
825 {
826         struct dn_scp *scp = DN_SK(sk);
827         struct dn_skb_cb *cb = DN_SKB_CB(skb);
828 
829         if (cb->rt_flags & DN_RT_F_RTS) {
830                 if (cb->nsp_flags == 0x18 || cb->nsp_flags == 0x68)
831                         dn_returned_conn_init(sk, skb);
832                 else
833                         kfree_skb(skb);
834                 return NET_RX_SUCCESS;
835         }
836 
837         /*
838          * Control packet.
839          */
840         if ((cb->nsp_flags & 0x0c) == 0x08) {
841                 switch (cb->nsp_flags & 0x70) {
842                 case 0x10:
843                 case 0x60:
844                         dn_nsp_conn_init(sk, skb);
845                         break;
846                 case 0x20:
847                         dn_nsp_conn_conf(sk, skb);
848                         break;
849                 case 0x30:
850                         dn_nsp_disc_init(sk, skb);
851                         break;
852                 case 0x40:
853                         dn_nsp_disc_conf(sk, skb);
854                         break;
855                 }
856 
857         } else if (cb->nsp_flags == 0x24) {
858                 /*
859                  * Special for connacks, 'cos they don't have
860                  * ack data or ack otherdata info.
861                  */
862                 dn_nsp_conn_ack(sk, skb);
863         } else {
864                 int other = 1;
865 
866                 /* both data and ack frames can kick a CC socket into RUN */
867                 if ((scp->state == DN_CC) && !sock_flag(sk, SOCK_DEAD)) {
868                         scp->state = DN_RUN;
869                         sk->sk_state = TCP_ESTABLISHED;
870                         sk->sk_state_change(sk);
871                 }
872 
873                 if ((cb->nsp_flags & 0x1c) == 0)
874                         other = 0;
875                 if (cb->nsp_flags == 0x04)
876                         other = 0;
877 
878                 /*
879                  * Read out ack data here, this applies equally
880                  * to data, other data, link serivce and both
881                  * ack data and ack otherdata.
882                  */
883                 dn_process_ack(sk, skb, other);
884 
885                 /*
886                  * If we've some sort of data here then call a
887                  * suitable routine for dealing with it, otherwise
888                  * the packet is an ack and can be discarded.
889                  */
890                 if ((cb->nsp_flags & 0x0c) == 0) {
891 
892                         if (scp->state != DN_RUN)
893                                 goto free_out;
894 
895                         switch (cb->nsp_flags) {
896                         case 0x10: /* LS */
897                                 dn_nsp_linkservice(sk, skb);
898                                 break;
899                         case 0x30: /* OD */
900                                 dn_nsp_otherdata(sk, skb);
901                                 break;
902                         default:
903                                 dn_nsp_data(sk, skb);
904                         }
905 
906                 } else { /* Ack, chuck it out here */
907 free_out:
908                         kfree_skb(skb);
909                 }
910         }
911 
912         return NET_RX_SUCCESS;
913 }
914 
915 

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