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TOMOYO Linux Cross Reference
Linux/net/tipc/msg.c

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  1 /*
  2  * net/tipc/msg.c: TIPC message header routines
  3  *
  4  * Copyright (c) 2000-2006, 2014-2015, Ericsson AB
  5  * Copyright (c) 2005, 2010-2011, Wind River Systems
  6  * All rights reserved.
  7  *
  8  * Redistribution and use in source and binary forms, with or without
  9  * modification, are permitted provided that the following conditions are met:
 10  *
 11  * 1. Redistributions of source code must retain the above copyright
 12  *    notice, this list of conditions and the following disclaimer.
 13  * 2. Redistributions in binary form must reproduce the above copyright
 14  *    notice, this list of conditions and the following disclaimer in the
 15  *    documentation and/or other materials provided with the distribution.
 16  * 3. Neither the names of the copyright holders nor the names of its
 17  *    contributors may be used to endorse or promote products derived from
 18  *    this software without specific prior written permission.
 19  *
 20  * Alternatively, this software may be distributed under the terms of the
 21  * GNU General Public License ("GPL") version 2 as published by the Free
 22  * Software Foundation.
 23  *
 24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 34  * POSSIBILITY OF SUCH DAMAGE.
 35  */
 36 
 37 #include <net/sock.h>
 38 #include "core.h"
 39 #include "msg.h"
 40 #include "addr.h"
 41 #include "name_table.h"
 42 
 43 #define MAX_FORWARD_SIZE 1024
 44 #define BUF_HEADROOM (LL_MAX_HEADER + 48)
 45 #define BUF_TAILROOM 16
 46 
 47 static unsigned int align(unsigned int i)
 48 {
 49         return (i + 3) & ~3u;
 50 }
 51 
 52 /**
 53  * tipc_buf_acquire - creates a TIPC message buffer
 54  * @size: message size (including TIPC header)
 55  *
 56  * Returns a new buffer with data pointers set to the specified size.
 57  *
 58  * NOTE: Headroom is reserved to allow prepending of a data link header.
 59  *       There may also be unrequested tailroom present at the buffer's end.
 60  */
 61 struct sk_buff *tipc_buf_acquire(u32 size, gfp_t gfp)
 62 {
 63         struct sk_buff *skb;
 64         unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;
 65 
 66         skb = alloc_skb_fclone(buf_size, gfp);
 67         if (skb) {
 68                 skb_reserve(skb, BUF_HEADROOM);
 69                 skb_put(skb, size);
 70                 skb->next = NULL;
 71         }
 72         return skb;
 73 }
 74 
 75 void tipc_msg_init(u32 own_node, struct tipc_msg *m, u32 user, u32 type,
 76                    u32 hsize, u32 dnode)
 77 {
 78         memset(m, 0, hsize);
 79         msg_set_version(m);
 80         msg_set_user(m, user);
 81         msg_set_hdr_sz(m, hsize);
 82         msg_set_size(m, hsize);
 83         msg_set_prevnode(m, own_node);
 84         msg_set_type(m, type);
 85         if (hsize > SHORT_H_SIZE) {
 86                 msg_set_orignode(m, own_node);
 87                 msg_set_destnode(m, dnode);
 88         }
 89 }
 90 
 91 struct sk_buff *tipc_msg_create(uint user, uint type,
 92                                 uint hdr_sz, uint data_sz, u32 dnode,
 93                                 u32 onode, u32 dport, u32 oport, int errcode)
 94 {
 95         struct tipc_msg *msg;
 96         struct sk_buff *buf;
 97 
 98         buf = tipc_buf_acquire(hdr_sz + data_sz, GFP_ATOMIC);
 99         if (unlikely(!buf))
100                 return NULL;
101 
102         msg = buf_msg(buf);
103         tipc_msg_init(onode, msg, user, type, hdr_sz, dnode);
104         msg_set_size(msg, hdr_sz + data_sz);
105         msg_set_origport(msg, oport);
106         msg_set_destport(msg, dport);
107         msg_set_errcode(msg, errcode);
108         if (hdr_sz > SHORT_H_SIZE) {
109                 msg_set_orignode(msg, onode);
110                 msg_set_destnode(msg, dnode);
111         }
112         return buf;
113 }
114 
115 /* tipc_buf_append(): Append a buffer to the fragment list of another buffer
116  * @*headbuf: in:  NULL for first frag, otherwise value returned from prev call
117  *            out: set when successful non-complete reassembly, otherwise NULL
118  * @*buf:     in:  the buffer to append. Always defined
119  *            out: head buf after successful complete reassembly, otherwise NULL
120  * Returns 1 when reassembly complete, otherwise 0
121  */
122 int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
123 {
124         struct sk_buff *head = *headbuf;
125         struct sk_buff *frag = *buf;
126         struct sk_buff *tail = NULL;
127         struct tipc_msg *msg;
128         u32 fragid;
129         int delta;
130         bool headstolen;
131 
132         if (!frag)
133                 goto err;
134 
135         msg = buf_msg(frag);
136         fragid = msg_type(msg);
137         frag->next = NULL;
138         skb_pull(frag, msg_hdr_sz(msg));
139 
140         if (fragid == FIRST_FRAGMENT) {
141                 if (unlikely(head))
142                         goto err;
143                 if (unlikely(skb_unclone(frag, GFP_ATOMIC)))
144                         goto err;
145                 head = *headbuf = frag;
146                 *buf = NULL;
147                 TIPC_SKB_CB(head)->tail = NULL;
148                 if (skb_is_nonlinear(head)) {
149                         skb_walk_frags(head, tail) {
150                                 TIPC_SKB_CB(head)->tail = tail;
151                         }
152                 } else {
153                         skb_frag_list_init(head);
154                 }
155                 return 0;
156         }
157 
158         if (!head)
159                 goto err;
160 
161         if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
162                 kfree_skb_partial(frag, headstolen);
163         } else {
164                 tail = TIPC_SKB_CB(head)->tail;
165                 if (!skb_has_frag_list(head))
166                         skb_shinfo(head)->frag_list = frag;
167                 else
168                         tail->next = frag;
169                 head->truesize += frag->truesize;
170                 head->data_len += frag->len;
171                 head->len += frag->len;
172                 TIPC_SKB_CB(head)->tail = frag;
173         }
174 
175         if (fragid == LAST_FRAGMENT) {
176                 TIPC_SKB_CB(head)->validated = false;
177                 if (unlikely(!tipc_msg_validate(head)))
178                         goto err;
179                 *buf = head;
180                 TIPC_SKB_CB(head)->tail = NULL;
181                 *headbuf = NULL;
182                 return 1;
183         }
184         *buf = NULL;
185         return 0;
186 err:
187         kfree_skb(*buf);
188         kfree_skb(*headbuf);
189         *buf = *headbuf = NULL;
190         return 0;
191 }
192 
193 /* tipc_msg_validate - validate basic format of received message
194  *
195  * This routine ensures a TIPC message has an acceptable header, and at least
196  * as much data as the header indicates it should.  The routine also ensures
197  * that the entire message header is stored in the main fragment of the message
198  * buffer, to simplify future access to message header fields.
199  *
200  * Note: Having extra info present in the message header or data areas is OK.
201  * TIPC will ignore the excess, under the assumption that it is optional info
202  * introduced by a later release of the protocol.
203  */
204 bool tipc_msg_validate(struct sk_buff *skb)
205 {
206         struct tipc_msg *msg;
207         int msz, hsz;
208 
209         if (unlikely(TIPC_SKB_CB(skb)->validated))
210                 return true;
211         if (unlikely(!pskb_may_pull(skb, MIN_H_SIZE)))
212                 return false;
213 
214         hsz = msg_hdr_sz(buf_msg(skb));
215         if (unlikely(hsz < MIN_H_SIZE) || (hsz > MAX_H_SIZE))
216                 return false;
217         if (unlikely(!pskb_may_pull(skb, hsz)))
218                 return false;
219 
220         msg = buf_msg(skb);
221         if (unlikely(msg_version(msg) != TIPC_VERSION))
222                 return false;
223 
224         msz = msg_size(msg);
225         if (unlikely(msz < hsz))
226                 return false;
227         if (unlikely((msz - hsz) > TIPC_MAX_USER_MSG_SIZE))
228                 return false;
229         if (unlikely(skb->len < msz))
230                 return false;
231 
232         TIPC_SKB_CB(skb)->validated = true;
233         return true;
234 }
235 
236 /**
237  * tipc_msg_build - create buffer chain containing specified header and data
238  * @mhdr: Message header, to be prepended to data
239  * @m: User message
240  * @dsz: Total length of user data
241  * @pktmax: Max packet size that can be used
242  * @list: Buffer or chain of buffers to be returned to caller
243  *
244  * Returns message data size or errno: -ENOMEM, -EFAULT
245  */
246 int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
247                    int offset, int dsz, int pktmax, struct sk_buff_head *list)
248 {
249         int mhsz = msg_hdr_sz(mhdr);
250         int msz = mhsz + dsz;
251         int pktno = 1;
252         int pktsz;
253         int pktrem = pktmax;
254         int drem = dsz;
255         struct tipc_msg pkthdr;
256         struct sk_buff *skb;
257         char *pktpos;
258         int rc;
259 
260         msg_set_size(mhdr, msz);
261 
262         /* No fragmentation needed? */
263         if (likely(msz <= pktmax)) {
264                 skb = tipc_buf_acquire(msz, GFP_KERNEL);
265                 if (unlikely(!skb))
266                         return -ENOMEM;
267                 skb_orphan(skb);
268                 __skb_queue_tail(list, skb);
269                 skb_copy_to_linear_data(skb, mhdr, mhsz);
270                 pktpos = skb->data + mhsz;
271                 if (copy_from_iter_full(pktpos, dsz, &m->msg_iter))
272                         return dsz;
273                 rc = -EFAULT;
274                 goto error;
275         }
276 
277         /* Prepare reusable fragment header */
278         tipc_msg_init(msg_prevnode(mhdr), &pkthdr, MSG_FRAGMENTER,
279                       FIRST_FRAGMENT, INT_H_SIZE, msg_destnode(mhdr));
280         msg_set_size(&pkthdr, pktmax);
281         msg_set_fragm_no(&pkthdr, pktno);
282         msg_set_importance(&pkthdr, msg_importance(mhdr));
283 
284         /* Prepare first fragment */
285         skb = tipc_buf_acquire(pktmax, GFP_KERNEL);
286         if (!skb)
287                 return -ENOMEM;
288         skb_orphan(skb);
289         __skb_queue_tail(list, skb);
290         pktpos = skb->data;
291         skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
292         pktpos += INT_H_SIZE;
293         pktrem -= INT_H_SIZE;
294         skb_copy_to_linear_data_offset(skb, INT_H_SIZE, mhdr, mhsz);
295         pktpos += mhsz;
296         pktrem -= mhsz;
297 
298         do {
299                 if (drem < pktrem)
300                         pktrem = drem;
301 
302                 if (!copy_from_iter_full(pktpos, pktrem, &m->msg_iter)) {
303                         rc = -EFAULT;
304                         goto error;
305                 }
306                 drem -= pktrem;
307 
308                 if (!drem)
309                         break;
310 
311                 /* Prepare new fragment: */
312                 if (drem < (pktmax - INT_H_SIZE))
313                         pktsz = drem + INT_H_SIZE;
314                 else
315                         pktsz = pktmax;
316                 skb = tipc_buf_acquire(pktsz, GFP_KERNEL);
317                 if (!skb) {
318                         rc = -ENOMEM;
319                         goto error;
320                 }
321                 skb_orphan(skb);
322                 __skb_queue_tail(list, skb);
323                 msg_set_type(&pkthdr, FRAGMENT);
324                 msg_set_size(&pkthdr, pktsz);
325                 msg_set_fragm_no(&pkthdr, ++pktno);
326                 skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
327                 pktpos = skb->data + INT_H_SIZE;
328                 pktrem = pktsz - INT_H_SIZE;
329 
330         } while (1);
331         msg_set_type(buf_msg(skb), LAST_FRAGMENT);
332         return dsz;
333 error:
334         __skb_queue_purge(list);
335         __skb_queue_head_init(list);
336         return rc;
337 }
338 
339 /**
340  * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
341  * @skb: the buffer to append to ("bundle")
342  * @msg:  message to be appended
343  * @mtu:  max allowable size for the bundle buffer
344  * Consumes buffer if successful
345  * Returns true if bundling could be performed, otherwise false
346  */
347 bool tipc_msg_bundle(struct sk_buff *skb, struct tipc_msg *msg, u32 mtu)
348 {
349         struct tipc_msg *bmsg;
350         unsigned int bsz;
351         unsigned int msz = msg_size(msg);
352         u32 start, pad;
353         u32 max = mtu - INT_H_SIZE;
354 
355         if (likely(msg_user(msg) == MSG_FRAGMENTER))
356                 return false;
357         if (!skb)
358                 return false;
359         bmsg = buf_msg(skb);
360         bsz = msg_size(bmsg);
361         start = align(bsz);
362         pad = start - bsz;
363 
364         if (unlikely(msg_user(msg) == TUNNEL_PROTOCOL))
365                 return false;
366         if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
367                 return false;
368         if (unlikely(msg_user(bmsg) != MSG_BUNDLER))
369                 return false;
370         if (unlikely(skb_tailroom(skb) < (pad + msz)))
371                 return false;
372         if (unlikely(max < (start + msz)))
373                 return false;
374         if ((msg_importance(msg) < TIPC_SYSTEM_IMPORTANCE) &&
375             (msg_importance(bmsg) == TIPC_SYSTEM_IMPORTANCE))
376                 return false;
377 
378         skb_put(skb, pad + msz);
379         skb_copy_to_linear_data_offset(skb, start, msg, msz);
380         msg_set_size(bmsg, start + msz);
381         msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
382         return true;
383 }
384 
385 /**
386  *  tipc_msg_extract(): extract bundled inner packet from buffer
387  *  @skb: buffer to be extracted from.
388  *  @iskb: extracted inner buffer, to be returned
389  *  @pos: position in outer message of msg to be extracted.
390  *        Returns position of next msg
391  *  Consumes outer buffer when last packet extracted
392  *  Returns true when when there is an extracted buffer, otherwise false
393  */
394 bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
395 {
396         struct tipc_msg *msg;
397         int imsz, offset;
398 
399         *iskb = NULL;
400         if (unlikely(skb_linearize(skb)))
401                 goto none;
402 
403         msg = buf_msg(skb);
404         offset = msg_hdr_sz(msg) + *pos;
405         if (unlikely(offset > (msg_size(msg) - MIN_H_SIZE)))
406                 goto none;
407 
408         *iskb = skb_clone(skb, GFP_ATOMIC);
409         if (unlikely(!*iskb))
410                 goto none;
411         skb_pull(*iskb, offset);
412         imsz = msg_size(buf_msg(*iskb));
413         skb_trim(*iskb, imsz);
414         if (unlikely(!tipc_msg_validate(*iskb)))
415                 goto none;
416         *pos += align(imsz);
417         return true;
418 none:
419         kfree_skb(skb);
420         kfree_skb(*iskb);
421         *iskb = NULL;
422         return false;
423 }
424 
425 /**
426  * tipc_msg_make_bundle(): Create bundle buf and append message to its tail
427  * @list: the buffer chain, where head is the buffer to replace/append
428  * @skb: buffer to be created, appended to and returned in case of success
429  * @msg: message to be appended
430  * @mtu: max allowable size for the bundle buffer, inclusive header
431  * @dnode: destination node for message. (Not always present in header)
432  * Returns true if success, otherwise false
433  */
434 bool tipc_msg_make_bundle(struct sk_buff **skb,  struct tipc_msg *msg,
435                           u32 mtu, u32 dnode)
436 {
437         struct sk_buff *_skb;
438         struct tipc_msg *bmsg;
439         u32 msz = msg_size(msg);
440         u32 max = mtu - INT_H_SIZE;
441 
442         if (msg_user(msg) == MSG_FRAGMENTER)
443                 return false;
444         if (msg_user(msg) == TUNNEL_PROTOCOL)
445                 return false;
446         if (msg_user(msg) == BCAST_PROTOCOL)
447                 return false;
448         if (msz > (max / 2))
449                 return false;
450 
451         _skb = tipc_buf_acquire(max, GFP_ATOMIC);
452         if (!_skb)
453                 return false;
454 
455         skb_trim(_skb, INT_H_SIZE);
456         bmsg = buf_msg(_skb);
457         tipc_msg_init(msg_prevnode(msg), bmsg, MSG_BUNDLER, 0,
458                       INT_H_SIZE, dnode);
459         if (msg_isdata(msg))
460                 msg_set_importance(bmsg, TIPC_CRITICAL_IMPORTANCE);
461         else
462                 msg_set_importance(bmsg, TIPC_SYSTEM_IMPORTANCE);
463         msg_set_seqno(bmsg, msg_seqno(msg));
464         msg_set_ack(bmsg, msg_ack(msg));
465         msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
466         tipc_msg_bundle(_skb, msg, mtu);
467         *skb = _skb;
468         return true;
469 }
470 
471 /**
472  * tipc_msg_reverse(): swap source and destination addresses and add error code
473  * @own_node: originating node id for reversed message
474  * @skb:  buffer containing message to be reversed; may be replaced.
475  * @err:  error code to be set in message, if any
476  * Consumes buffer at failure
477  * Returns true if success, otherwise false
478  */
479 bool tipc_msg_reverse(u32 own_node,  struct sk_buff **skb, int err)
480 {
481         struct sk_buff *_skb = *skb;
482         struct tipc_msg *hdr;
483         struct tipc_msg ohdr;
484         int dlen;
485 
486         if (skb_linearize(_skb))
487                 goto exit;
488         hdr = buf_msg(_skb);
489         dlen = min_t(uint, msg_data_sz(hdr), MAX_FORWARD_SIZE);
490         if (msg_dest_droppable(hdr))
491                 goto exit;
492         if (msg_errcode(hdr))
493                 goto exit;
494 
495         /* Take a copy of original header before altering message */
496         memcpy(&ohdr, hdr, msg_hdr_sz(hdr));
497 
498         /* Never return SHORT header; expand by replacing buffer if necessary */
499         if (msg_short(hdr)) {
500                 *skb = tipc_buf_acquire(BASIC_H_SIZE + dlen, GFP_ATOMIC);
501                 if (!*skb)
502                         goto exit;
503                 memcpy((*skb)->data + BASIC_H_SIZE, msg_data(hdr), dlen);
504                 kfree_skb(_skb);
505                 _skb = *skb;
506                 hdr = buf_msg(_skb);
507                 memcpy(hdr, &ohdr, BASIC_H_SIZE);
508                 msg_set_hdr_sz(hdr, BASIC_H_SIZE);
509         }
510 
511         if (skb_cloned(_skb) &&
512             pskb_expand_head(_skb, BUF_HEADROOM, BUF_TAILROOM, GFP_ATOMIC))
513                 goto exit;
514 
515         /* reassign after skb header modifications */
516         hdr = buf_msg(_skb);
517         /* Now reverse the concerned fields */
518         msg_set_errcode(hdr, err);
519         msg_set_non_seq(hdr, 0);
520         msg_set_origport(hdr, msg_destport(&ohdr));
521         msg_set_destport(hdr, msg_origport(&ohdr));
522         msg_set_destnode(hdr, msg_prevnode(&ohdr));
523         msg_set_prevnode(hdr, own_node);
524         msg_set_orignode(hdr, own_node);
525         msg_set_size(hdr, msg_hdr_sz(hdr) + dlen);
526         skb_trim(_skb, msg_size(hdr));
527         skb_orphan(_skb);
528         return true;
529 exit:
530         kfree_skb(_skb);
531         *skb = NULL;
532         return false;
533 }
534 
535 /**
536  * tipc_msg_lookup_dest(): try to find new destination for named message
537  * @skb: the buffer containing the message.
538  * @err: error code to be used by caller if lookup fails
539  * Does not consume buffer
540  * Returns true if a destination is found, false otherwise
541  */
542 bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
543 {
544         struct tipc_msg *msg = buf_msg(skb);
545         u32 dport, dnode;
546         u32 onode = tipc_own_addr(net);
547 
548         if (!msg_isdata(msg))
549                 return false;
550         if (!msg_named(msg))
551                 return false;
552         if (msg_errcode(msg))
553                 return false;
554         *err = TIPC_ERR_NO_NAME;
555         if (skb_linearize(skb))
556                 return false;
557         msg = buf_msg(skb);
558         if (msg_reroute_cnt(msg))
559                 return false;
560         dnode = addr_domain(net, msg_lookup_scope(msg));
561         dport = tipc_nametbl_translate(net, msg_nametype(msg),
562                                        msg_nameinst(msg), &dnode);
563         if (!dport)
564                 return false;
565         msg_incr_reroute_cnt(msg);
566         if (dnode != onode)
567                 msg_set_prevnode(msg, onode);
568         msg_set_destnode(msg, dnode);
569         msg_set_destport(msg, dport);
570         *err = TIPC_OK;
571         return true;
572 }
573 
574 /* tipc_msg_reassemble() - clone a buffer chain of fragments and
575  *                         reassemble the clones into one message
576  */
577 bool tipc_msg_reassemble(struct sk_buff_head *list, struct sk_buff_head *rcvq)
578 {
579         struct sk_buff *skb, *_skb;
580         struct sk_buff *frag = NULL;
581         struct sk_buff *head = NULL;
582         int hdr_len;
583 
584         /* Copy header if single buffer */
585         if (skb_queue_len(list) == 1) {
586                 skb = skb_peek(list);
587                 hdr_len = skb_headroom(skb) + msg_hdr_sz(buf_msg(skb));
588                 _skb = __pskb_copy(skb, hdr_len, GFP_ATOMIC);
589                 if (!_skb)
590                         return false;
591                 __skb_queue_tail(rcvq, _skb);
592                 return true;
593         }
594 
595         /* Clone all fragments and reassemble */
596         skb_queue_walk(list, skb) {
597                 frag = skb_clone(skb, GFP_ATOMIC);
598                 if (!frag)
599                         goto error;
600                 frag->next = NULL;
601                 if (tipc_buf_append(&head, &frag))
602                         break;
603                 if (!head)
604                         goto error;
605         }
606         __skb_queue_tail(rcvq, frag);
607         return true;
608 error:
609         pr_warn("Failed do clone local mcast rcv buffer\n");
610         kfree_skb(head);
611         return false;
612 }
613 
614 bool tipc_msg_pskb_copy(u32 dst, struct sk_buff_head *msg,
615                         struct sk_buff_head *cpy)
616 {
617         struct sk_buff *skb, *_skb;
618 
619         skb_queue_walk(msg, skb) {
620                 _skb = pskb_copy(skb, GFP_ATOMIC);
621                 if (!_skb) {
622                         __skb_queue_purge(cpy);
623                         return false;
624                 }
625                 msg_set_destnode(buf_msg(_skb), dst);
626                 __skb_queue_tail(cpy, _skb);
627         }
628         return true;
629 }
630 
631 /* tipc_skb_queue_sorted(); sort pkt into list according to sequence number
632  * @list: list to be appended to
633  * @seqno: sequence number of buffer to add
634  * @skb: buffer to add
635  */
636 void __tipc_skb_queue_sorted(struct sk_buff_head *list, u16 seqno,
637                              struct sk_buff *skb)
638 {
639         struct sk_buff *_skb, *tmp;
640 
641         if (skb_queue_empty(list) || less(seqno, buf_seqno(skb_peek(list)))) {
642                 __skb_queue_head(list, skb);
643                 return;
644         }
645 
646         if (more(seqno, buf_seqno(skb_peek_tail(list)))) {
647                 __skb_queue_tail(list, skb);
648                 return;
649         }
650 
651         skb_queue_walk_safe(list, _skb, tmp) {
652                 if (more(seqno, buf_seqno(_skb)))
653                         continue;
654                 if (seqno == buf_seqno(_skb))
655                         break;
656                 __skb_queue_before(list, _skb, skb);
657                 return;
658         }
659         kfree_skb(skb);
660 }
661 

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