xref: /openbmc/linux/net/tipc/msg.c (revision 7fd53f41)
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 #include "crypto.h"
43 
44 #define MAX_FORWARD_SIZE 1024
45 #ifdef CONFIG_TIPC_CRYPTO
46 #define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
47 #define BUF_TAILROOM (TIPC_AES_GCM_TAG_SIZE)
48 #else
49 #define BUF_HEADROOM (LL_MAX_HEADER + 48)
50 #define BUF_TAILROOM 16
51 #endif
52 
53 static unsigned int align(unsigned int i)
54 {
55 	return (i + 3) & ~3u;
56 }
57 
58 /**
59  * tipc_buf_acquire - creates a TIPC message buffer
60  * @size: message size (including TIPC header)
61  * @gfp: memory allocation flags
62  *
63  * Return: a new buffer with data pointers set to the specified size.
64  *
65  * NOTE:
66  * Headroom is reserved to allow prepending of a data link header.
67  * There may also be unrequested tailroom present at the buffer's end.
68  */
69 struct sk_buff *tipc_buf_acquire(u32 size, gfp_t gfp)
70 {
71 	struct sk_buff *skb;
72 #ifdef CONFIG_TIPC_CRYPTO
73 	unsigned int buf_size = (BUF_HEADROOM + size + BUF_TAILROOM + 3) & ~3u;
74 #else
75 	unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;
76 #endif
77 
78 	skb = alloc_skb_fclone(buf_size, gfp);
79 	if (skb) {
80 		skb_reserve(skb, BUF_HEADROOM);
81 		skb_put(skb, size);
82 		skb->next = NULL;
83 	}
84 	return skb;
85 }
86 
87 void tipc_msg_init(u32 own_node, struct tipc_msg *m, u32 user, u32 type,
88 		   u32 hsize, u32 dnode)
89 {
90 	memset(m, 0, hsize);
91 	msg_set_version(m);
92 	msg_set_user(m, user);
93 	msg_set_hdr_sz(m, hsize);
94 	msg_set_size(m, hsize);
95 	msg_set_prevnode(m, own_node);
96 	msg_set_type(m, type);
97 	if (hsize > SHORT_H_SIZE) {
98 		msg_set_orignode(m, own_node);
99 		msg_set_destnode(m, dnode);
100 	}
101 }
102 
103 struct sk_buff *tipc_msg_create(uint user, uint type,
104 				uint hdr_sz, uint data_sz, u32 dnode,
105 				u32 onode, u32 dport, u32 oport, int errcode)
106 {
107 	struct tipc_msg *msg;
108 	struct sk_buff *buf;
109 
110 	buf = tipc_buf_acquire(hdr_sz + data_sz, GFP_ATOMIC);
111 	if (unlikely(!buf))
112 		return NULL;
113 
114 	msg = buf_msg(buf);
115 	tipc_msg_init(onode, msg, user, type, hdr_sz, dnode);
116 	msg_set_size(msg, hdr_sz + data_sz);
117 	msg_set_origport(msg, oport);
118 	msg_set_destport(msg, dport);
119 	msg_set_errcode(msg, errcode);
120 	return buf;
121 }
122 
123 /* tipc_buf_append(): Append a buffer to the fragment list of another buffer
124  * @*headbuf: in:  NULL for first frag, otherwise value returned from prev call
125  *            out: set when successful non-complete reassembly, otherwise NULL
126  * @*buf:     in:  the buffer to append. Always defined
127  *            out: head buf after successful complete reassembly, otherwise NULL
128  * Returns 1 when reassembly complete, otherwise 0
129  */
130 int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
131 {
132 	struct sk_buff *head = *headbuf;
133 	struct sk_buff *frag = *buf;
134 	struct sk_buff *tail = NULL;
135 	struct tipc_msg *msg;
136 	u32 fragid;
137 	int delta;
138 	bool headstolen;
139 
140 	if (!frag)
141 		goto err;
142 
143 	msg = buf_msg(frag);
144 	fragid = msg_type(msg);
145 	frag->next = NULL;
146 	skb_pull(frag, msg_hdr_sz(msg));
147 
148 	if (fragid == FIRST_FRAGMENT) {
149 		if (unlikely(head))
150 			goto err;
151 		*buf = NULL;
152 		frag = skb_unshare(frag, GFP_ATOMIC);
153 		if (unlikely(!frag))
154 			goto err;
155 		head = *headbuf = frag;
156 		TIPC_SKB_CB(head)->tail = NULL;
157 		if (skb_is_nonlinear(head)) {
158 			skb_walk_frags(head, tail) {
159 				TIPC_SKB_CB(head)->tail = tail;
160 			}
161 		} else {
162 			skb_frag_list_init(head);
163 		}
164 		return 0;
165 	}
166 
167 	if (!head)
168 		goto err;
169 
170 	if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
171 		kfree_skb_partial(frag, headstolen);
172 	} else {
173 		tail = TIPC_SKB_CB(head)->tail;
174 		if (!skb_has_frag_list(head))
175 			skb_shinfo(head)->frag_list = frag;
176 		else
177 			tail->next = frag;
178 		head->truesize += frag->truesize;
179 		head->data_len += frag->len;
180 		head->len += frag->len;
181 		TIPC_SKB_CB(head)->tail = frag;
182 	}
183 
184 	if (fragid == LAST_FRAGMENT) {
185 		TIPC_SKB_CB(head)->validated = 0;
186 		if (unlikely(!tipc_msg_validate(&head)))
187 			goto err;
188 		*buf = head;
189 		TIPC_SKB_CB(head)->tail = NULL;
190 		*headbuf = NULL;
191 		return 1;
192 	}
193 	*buf = NULL;
194 	return 0;
195 err:
196 	kfree_skb(*buf);
197 	kfree_skb(*headbuf);
198 	*buf = *headbuf = NULL;
199 	return 0;
200 }
201 
202 /**
203  * tipc_msg_append(): Append data to tail of an existing buffer queue
204  * @_hdr: header to be used
205  * @m: the data to be appended
206  * @mss: max allowable size of buffer
207  * @dlen: size of data to be appended
208  * @txq: queue to append to
209  *
210  * Return: the number of 1k blocks appended or errno value
211  */
212 int tipc_msg_append(struct tipc_msg *_hdr, struct msghdr *m, int dlen,
213 		    int mss, struct sk_buff_head *txq)
214 {
215 	struct sk_buff *skb;
216 	int accounted, total, curr;
217 	int mlen, cpy, rem = dlen;
218 	struct tipc_msg *hdr;
219 
220 	skb = skb_peek_tail(txq);
221 	accounted = skb ? msg_blocks(buf_msg(skb)) : 0;
222 	total = accounted;
223 
224 	do {
225 		if (!skb || skb->len >= mss) {
226 			skb = tipc_buf_acquire(mss, GFP_KERNEL);
227 			if (unlikely(!skb))
228 				return -ENOMEM;
229 			skb_orphan(skb);
230 			skb_trim(skb, MIN_H_SIZE);
231 			hdr = buf_msg(skb);
232 			skb_copy_to_linear_data(skb, _hdr, MIN_H_SIZE);
233 			msg_set_hdr_sz(hdr, MIN_H_SIZE);
234 			msg_set_size(hdr, MIN_H_SIZE);
235 			__skb_queue_tail(txq, skb);
236 			total += 1;
237 		}
238 		hdr = buf_msg(skb);
239 		curr = msg_blocks(hdr);
240 		mlen = msg_size(hdr);
241 		cpy = min_t(size_t, rem, mss - mlen);
242 		if (cpy != copy_from_iter(skb->data + mlen, cpy, &m->msg_iter))
243 			return -EFAULT;
244 		msg_set_size(hdr, mlen + cpy);
245 		skb_put(skb, cpy);
246 		rem -= cpy;
247 		total += msg_blocks(hdr) - curr;
248 	} while (rem > 0);
249 	return total - accounted;
250 }
251 
252 /* tipc_msg_validate - validate basic format of received message
253  *
254  * This routine ensures a TIPC message has an acceptable header, and at least
255  * as much data as the header indicates it should.  The routine also ensures
256  * that the entire message header is stored in the main fragment of the message
257  * buffer, to simplify future access to message header fields.
258  *
259  * Note: Having extra info present in the message header or data areas is OK.
260  * TIPC will ignore the excess, under the assumption that it is optional info
261  * introduced by a later release of the protocol.
262  */
263 bool tipc_msg_validate(struct sk_buff **_skb)
264 {
265 	struct sk_buff *skb = *_skb;
266 	struct tipc_msg *hdr;
267 	int msz, hsz;
268 
269 	/* Ensure that flow control ratio condition is satisfied */
270 	if (unlikely(skb->truesize / buf_roundup_len(skb) >= 4)) {
271 		skb = skb_copy_expand(skb, BUF_HEADROOM, 0, GFP_ATOMIC);
272 		if (!skb)
273 			return false;
274 		kfree_skb(*_skb);
275 		*_skb = skb;
276 	}
277 
278 	if (unlikely(TIPC_SKB_CB(skb)->validated))
279 		return true;
280 
281 	if (unlikely(!pskb_may_pull(skb, MIN_H_SIZE)))
282 		return false;
283 
284 	hsz = msg_hdr_sz(buf_msg(skb));
285 	if (unlikely(hsz < MIN_H_SIZE) || (hsz > MAX_H_SIZE))
286 		return false;
287 	if (unlikely(!pskb_may_pull(skb, hsz)))
288 		return false;
289 
290 	hdr = buf_msg(skb);
291 	if (unlikely(msg_version(hdr) != TIPC_VERSION))
292 		return false;
293 
294 	msz = msg_size(hdr);
295 	if (unlikely(msz < hsz))
296 		return false;
297 	if (unlikely((msz - hsz) > TIPC_MAX_USER_MSG_SIZE))
298 		return false;
299 	if (unlikely(skb->len < msz))
300 		return false;
301 
302 	TIPC_SKB_CB(skb)->validated = 1;
303 	return true;
304 }
305 
306 /**
307  * tipc_msg_fragment - build a fragment skb list for TIPC message
308  *
309  * @skb: TIPC message skb
310  * @hdr: internal msg header to be put on the top of the fragments
311  * @pktmax: max size of a fragment incl. the header
312  * @frags: returned fragment skb list
313  *
314  * Return: 0 if the fragmentation is successful, otherwise: -EINVAL
315  * or -ENOMEM
316  */
317 int tipc_msg_fragment(struct sk_buff *skb, const struct tipc_msg *hdr,
318 		      int pktmax, struct sk_buff_head *frags)
319 {
320 	int pktno, nof_fragms, dsz, dmax, eat;
321 	struct tipc_msg *_hdr;
322 	struct sk_buff *_skb;
323 	u8 *data;
324 
325 	/* Non-linear buffer? */
326 	if (skb_linearize(skb))
327 		return -ENOMEM;
328 
329 	data = (u8 *)skb->data;
330 	dsz = msg_size(buf_msg(skb));
331 	dmax = pktmax - INT_H_SIZE;
332 	if (dsz <= dmax || !dmax)
333 		return -EINVAL;
334 
335 	nof_fragms = dsz / dmax + 1;
336 	for (pktno = 1; pktno <= nof_fragms; pktno++) {
337 		if (pktno < nof_fragms)
338 			eat = dmax;
339 		else
340 			eat = dsz % dmax;
341 		/* Allocate a new fragment */
342 		_skb = tipc_buf_acquire(INT_H_SIZE + eat, GFP_ATOMIC);
343 		if (!_skb)
344 			goto error;
345 		skb_orphan(_skb);
346 		__skb_queue_tail(frags, _skb);
347 		/* Copy header & data to the fragment */
348 		skb_copy_to_linear_data(_skb, hdr, INT_H_SIZE);
349 		skb_copy_to_linear_data_offset(_skb, INT_H_SIZE, data, eat);
350 		data += eat;
351 		/* Update the fragment's header */
352 		_hdr = buf_msg(_skb);
353 		msg_set_fragm_no(_hdr, pktno);
354 		msg_set_nof_fragms(_hdr, nof_fragms);
355 		msg_set_size(_hdr, INT_H_SIZE + eat);
356 	}
357 	return 0;
358 
359 error:
360 	__skb_queue_purge(frags);
361 	__skb_queue_head_init(frags);
362 	return -ENOMEM;
363 }
364 
365 /**
366  * tipc_msg_build - create buffer chain containing specified header and data
367  * @mhdr: Message header, to be prepended to data
368  * @m: User message
369  * @offset: buffer offset for fragmented messages (FIXME)
370  * @dsz: Total length of user data
371  * @pktmax: Max packet size that can be used
372  * @list: Buffer or chain of buffers to be returned to caller
373  *
374  * Note that the recursive call we are making here is safe, since it can
375  * logically go only one further level down.
376  *
377  * Return: message data size or errno: -ENOMEM, -EFAULT
378  */
379 int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m, int offset,
380 		   int dsz, int pktmax, struct sk_buff_head *list)
381 {
382 	int mhsz = msg_hdr_sz(mhdr);
383 	struct tipc_msg pkthdr;
384 	int msz = mhsz + dsz;
385 	int pktrem = pktmax;
386 	struct sk_buff *skb;
387 	int drem = dsz;
388 	int pktno = 1;
389 	char *pktpos;
390 	int pktsz;
391 	int rc;
392 
393 	msg_set_size(mhdr, msz);
394 
395 	/* No fragmentation needed? */
396 	if (likely(msz <= pktmax)) {
397 		skb = tipc_buf_acquire(msz, GFP_KERNEL);
398 
399 		/* Fall back to smaller MTU if node local message */
400 		if (unlikely(!skb)) {
401 			if (pktmax != MAX_MSG_SIZE)
402 				return -ENOMEM;
403 			rc = tipc_msg_build(mhdr, m, offset, dsz, FB_MTU, list);
404 			if (rc != dsz)
405 				return rc;
406 			if (tipc_msg_assemble(list))
407 				return dsz;
408 			return -ENOMEM;
409 		}
410 		skb_orphan(skb);
411 		__skb_queue_tail(list, skb);
412 		skb_copy_to_linear_data(skb, mhdr, mhsz);
413 		pktpos = skb->data + mhsz;
414 		if (copy_from_iter_full(pktpos, dsz, &m->msg_iter))
415 			return dsz;
416 		rc = -EFAULT;
417 		goto error;
418 	}
419 
420 	/* Prepare reusable fragment header */
421 	tipc_msg_init(msg_prevnode(mhdr), &pkthdr, MSG_FRAGMENTER,
422 		      FIRST_FRAGMENT, INT_H_SIZE, msg_destnode(mhdr));
423 	msg_set_size(&pkthdr, pktmax);
424 	msg_set_fragm_no(&pkthdr, pktno);
425 	msg_set_importance(&pkthdr, msg_importance(mhdr));
426 
427 	/* Prepare first fragment */
428 	skb = tipc_buf_acquire(pktmax, GFP_KERNEL);
429 	if (!skb)
430 		return -ENOMEM;
431 	skb_orphan(skb);
432 	__skb_queue_tail(list, skb);
433 	pktpos = skb->data;
434 	skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
435 	pktpos += INT_H_SIZE;
436 	pktrem -= INT_H_SIZE;
437 	skb_copy_to_linear_data_offset(skb, INT_H_SIZE, mhdr, mhsz);
438 	pktpos += mhsz;
439 	pktrem -= mhsz;
440 
441 	do {
442 		if (drem < pktrem)
443 			pktrem = drem;
444 
445 		if (!copy_from_iter_full(pktpos, pktrem, &m->msg_iter)) {
446 			rc = -EFAULT;
447 			goto error;
448 		}
449 		drem -= pktrem;
450 
451 		if (!drem)
452 			break;
453 
454 		/* Prepare new fragment: */
455 		if (drem < (pktmax - INT_H_SIZE))
456 			pktsz = drem + INT_H_SIZE;
457 		else
458 			pktsz = pktmax;
459 		skb = tipc_buf_acquire(pktsz, GFP_KERNEL);
460 		if (!skb) {
461 			rc = -ENOMEM;
462 			goto error;
463 		}
464 		skb_orphan(skb);
465 		__skb_queue_tail(list, skb);
466 		msg_set_type(&pkthdr, FRAGMENT);
467 		msg_set_size(&pkthdr, pktsz);
468 		msg_set_fragm_no(&pkthdr, ++pktno);
469 		skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
470 		pktpos = skb->data + INT_H_SIZE;
471 		pktrem = pktsz - INT_H_SIZE;
472 
473 	} while (1);
474 	msg_set_type(buf_msg(skb), LAST_FRAGMENT);
475 	return dsz;
476 error:
477 	__skb_queue_purge(list);
478 	__skb_queue_head_init(list);
479 	return rc;
480 }
481 
482 /**
483  * tipc_msg_bundle - Append contents of a buffer to tail of an existing one
484  * @bskb: the bundle buffer to append to
485  * @msg: message to be appended
486  * @max: max allowable size for the bundle buffer
487  *
488  * Return: "true" if bundling has been performed, otherwise "false"
489  */
490 static bool tipc_msg_bundle(struct sk_buff *bskb, struct tipc_msg *msg,
491 			    u32 max)
492 {
493 	struct tipc_msg *bmsg = buf_msg(bskb);
494 	u32 msz, bsz, offset, pad;
495 
496 	msz = msg_size(msg);
497 	bsz = msg_size(bmsg);
498 	offset = align(bsz);
499 	pad = offset - bsz;
500 
501 	if (unlikely(skb_tailroom(bskb) < (pad + msz)))
502 		return false;
503 	if (unlikely(max < (offset + msz)))
504 		return false;
505 
506 	skb_put(bskb, pad + msz);
507 	skb_copy_to_linear_data_offset(bskb, offset, msg, msz);
508 	msg_set_size(bmsg, offset + msz);
509 	msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
510 	return true;
511 }
512 
513 /**
514  * tipc_msg_try_bundle - Try to bundle a new message to the last one
515  * @tskb: the last/target message to which the new one will be appended
516  * @skb: the new message skb pointer
517  * @mss: max message size (header inclusive)
518  * @dnode: destination node for the message
519  * @new_bundle: if this call made a new bundle or not
520  *
521  * Return: "true" if the new message skb is potential for bundling this time or
522  * later, in the case a bundling has been done this time, the skb is consumed
523  * (the skb pointer = NULL).
524  * Otherwise, "false" if the skb cannot be bundled at all.
525  */
526 bool tipc_msg_try_bundle(struct sk_buff *tskb, struct sk_buff **skb, u32 mss,
527 			 u32 dnode, bool *new_bundle)
528 {
529 	struct tipc_msg *msg, *inner, *outer;
530 	u32 tsz;
531 
532 	/* First, check if the new buffer is suitable for bundling */
533 	msg = buf_msg(*skb);
534 	if (msg_user(msg) == MSG_FRAGMENTER)
535 		return false;
536 	if (msg_user(msg) == TUNNEL_PROTOCOL)
537 		return false;
538 	if (msg_user(msg) == BCAST_PROTOCOL)
539 		return false;
540 	if (mss <= INT_H_SIZE + msg_size(msg))
541 		return false;
542 
543 	/* Ok, but the last/target buffer can be empty? */
544 	if (unlikely(!tskb))
545 		return true;
546 
547 	/* Is it a bundle already? Try to bundle the new message to it */
548 	if (msg_user(buf_msg(tskb)) == MSG_BUNDLER) {
549 		*new_bundle = false;
550 		goto bundle;
551 	}
552 
553 	/* Make a new bundle of the two messages if possible */
554 	tsz = msg_size(buf_msg(tskb));
555 	if (unlikely(mss < align(INT_H_SIZE + tsz) + msg_size(msg)))
556 		return true;
557 	if (unlikely(pskb_expand_head(tskb, INT_H_SIZE, mss - tsz - INT_H_SIZE,
558 				      GFP_ATOMIC)))
559 		return true;
560 	inner = buf_msg(tskb);
561 	skb_push(tskb, INT_H_SIZE);
562 	outer = buf_msg(tskb);
563 	tipc_msg_init(msg_prevnode(inner), outer, MSG_BUNDLER, 0, INT_H_SIZE,
564 		      dnode);
565 	msg_set_importance(outer, msg_importance(inner));
566 	msg_set_size(outer, INT_H_SIZE + tsz);
567 	msg_set_msgcnt(outer, 1);
568 	*new_bundle = true;
569 
570 bundle:
571 	if (likely(tipc_msg_bundle(tskb, msg, mss))) {
572 		consume_skb(*skb);
573 		*skb = NULL;
574 	}
575 	return true;
576 }
577 
578 /**
579  *  tipc_msg_extract(): extract bundled inner packet from buffer
580  *  @skb: buffer to be extracted from.
581  *  @iskb: extracted inner buffer, to be returned
582  *  @pos: position in outer message of msg to be extracted.
583  *  Returns position of next msg.
584  *  Consumes outer buffer when last packet extracted
585  *  Return: true when there is an extracted buffer, otherwise false
586  */
587 bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
588 {
589 	struct tipc_msg *hdr, *ihdr;
590 	int imsz;
591 
592 	*iskb = NULL;
593 	if (unlikely(skb_linearize(skb)))
594 		goto none;
595 
596 	hdr = buf_msg(skb);
597 	if (unlikely(*pos > (msg_data_sz(hdr) - MIN_H_SIZE)))
598 		goto none;
599 
600 	ihdr = (struct tipc_msg *)(msg_data(hdr) + *pos);
601 	imsz = msg_size(ihdr);
602 
603 	if ((*pos + imsz) > msg_data_sz(hdr))
604 		goto none;
605 
606 	*iskb = tipc_buf_acquire(imsz, GFP_ATOMIC);
607 	if (!*iskb)
608 		goto none;
609 
610 	skb_copy_to_linear_data(*iskb, ihdr, imsz);
611 	if (unlikely(!tipc_msg_validate(iskb)))
612 		goto none;
613 
614 	*pos += align(imsz);
615 	return true;
616 none:
617 	kfree_skb(skb);
618 	kfree_skb(*iskb);
619 	*iskb = NULL;
620 	return false;
621 }
622 
623 /**
624  * tipc_msg_reverse(): swap source and destination addresses and add error code
625  * @own_node: originating node id for reversed message
626  * @skb:  buffer containing message to be reversed; will be consumed
627  * @err:  error code to be set in message, if any
628  * Replaces consumed buffer with new one when successful
629  * Return: true if success, otherwise false
630  */
631 bool tipc_msg_reverse(u32 own_node,  struct sk_buff **skb, int err)
632 {
633 	struct sk_buff *_skb = *skb;
634 	struct tipc_msg *_hdr, *hdr;
635 	int hlen, dlen;
636 
637 	if (skb_linearize(_skb))
638 		goto exit;
639 	_hdr = buf_msg(_skb);
640 	dlen = min_t(uint, msg_data_sz(_hdr), MAX_FORWARD_SIZE);
641 	hlen = msg_hdr_sz(_hdr);
642 
643 	if (msg_dest_droppable(_hdr))
644 		goto exit;
645 	if (msg_errcode(_hdr))
646 		goto exit;
647 
648 	/* Never return SHORT header */
649 	if (hlen == SHORT_H_SIZE)
650 		hlen = BASIC_H_SIZE;
651 
652 	/* Don't return data along with SYN+, - sender has a clone */
653 	if (msg_is_syn(_hdr) && err == TIPC_ERR_OVERLOAD)
654 		dlen = 0;
655 
656 	/* Allocate new buffer to return */
657 	*skb = tipc_buf_acquire(hlen + dlen, GFP_ATOMIC);
658 	if (!*skb)
659 		goto exit;
660 	memcpy((*skb)->data, _skb->data, msg_hdr_sz(_hdr));
661 	memcpy((*skb)->data + hlen, msg_data(_hdr), dlen);
662 
663 	/* Build reverse header in new buffer */
664 	hdr = buf_msg(*skb);
665 	msg_set_hdr_sz(hdr, hlen);
666 	msg_set_errcode(hdr, err);
667 	msg_set_non_seq(hdr, 0);
668 	msg_set_origport(hdr, msg_destport(_hdr));
669 	msg_set_destport(hdr, msg_origport(_hdr));
670 	msg_set_destnode(hdr, msg_prevnode(_hdr));
671 	msg_set_prevnode(hdr, own_node);
672 	msg_set_orignode(hdr, own_node);
673 	msg_set_size(hdr, hlen + dlen);
674 	skb_orphan(_skb);
675 	kfree_skb(_skb);
676 	return true;
677 exit:
678 	kfree_skb(_skb);
679 	*skb = NULL;
680 	return false;
681 }
682 
683 bool tipc_msg_skb_clone(struct sk_buff_head *msg, struct sk_buff_head *cpy)
684 {
685 	struct sk_buff *skb, *_skb;
686 
687 	skb_queue_walk(msg, skb) {
688 		_skb = skb_clone(skb, GFP_ATOMIC);
689 		if (!_skb) {
690 			__skb_queue_purge(cpy);
691 			pr_err_ratelimited("Failed to clone buffer chain\n");
692 			return false;
693 		}
694 		__skb_queue_tail(cpy, _skb);
695 	}
696 	return true;
697 }
698 
699 /**
700  * tipc_msg_lookup_dest(): try to find new destination for named message
701  * @net: pointer to associated network namespace
702  * @skb: the buffer containing the message.
703  * @err: error code to be used by caller if lookup fails
704  * Does not consume buffer
705  * Return: true if a destination is found, false otherwise
706  */
707 bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
708 {
709 	struct tipc_msg *msg = buf_msg(skb);
710 	u32 dport, dnode;
711 	u32 onode = tipc_own_addr(net);
712 
713 	if (!msg_isdata(msg))
714 		return false;
715 	if (!msg_named(msg))
716 		return false;
717 	if (msg_errcode(msg))
718 		return false;
719 	*err = TIPC_ERR_NO_NAME;
720 	if (skb_linearize(skb))
721 		return false;
722 	msg = buf_msg(skb);
723 	if (msg_reroute_cnt(msg))
724 		return false;
725 	dnode = tipc_scope2node(net, msg_lookup_scope(msg));
726 	dport = tipc_nametbl_translate(net, msg_nametype(msg),
727 				       msg_nameinst(msg), &dnode);
728 	if (!dport)
729 		return false;
730 	msg_incr_reroute_cnt(msg);
731 	if (dnode != onode)
732 		msg_set_prevnode(msg, onode);
733 	msg_set_destnode(msg, dnode);
734 	msg_set_destport(msg, dport);
735 	*err = TIPC_OK;
736 
737 	return true;
738 }
739 
740 /* tipc_msg_assemble() - assemble chain of fragments into one message
741  */
742 bool tipc_msg_assemble(struct sk_buff_head *list)
743 {
744 	struct sk_buff *skb, *tmp = NULL;
745 
746 	if (skb_queue_len(list) == 1)
747 		return true;
748 
749 	while ((skb = __skb_dequeue(list))) {
750 		skb->next = NULL;
751 		if (tipc_buf_append(&tmp, &skb)) {
752 			__skb_queue_tail(list, skb);
753 			return true;
754 		}
755 		if (!tmp)
756 			break;
757 	}
758 	__skb_queue_purge(list);
759 	__skb_queue_head_init(list);
760 	pr_warn("Failed do assemble buffer\n");
761 	return false;
762 }
763 
764 /* tipc_msg_reassemble() - clone a buffer chain of fragments and
765  *                         reassemble the clones into one message
766  */
767 bool tipc_msg_reassemble(struct sk_buff_head *list, struct sk_buff_head *rcvq)
768 {
769 	struct sk_buff *skb, *_skb;
770 	struct sk_buff *frag = NULL;
771 	struct sk_buff *head = NULL;
772 	int hdr_len;
773 
774 	/* Copy header if single buffer */
775 	if (skb_queue_len(list) == 1) {
776 		skb = skb_peek(list);
777 		hdr_len = skb_headroom(skb) + msg_hdr_sz(buf_msg(skb));
778 		_skb = __pskb_copy(skb, hdr_len, GFP_ATOMIC);
779 		if (!_skb)
780 			return false;
781 		__skb_queue_tail(rcvq, _skb);
782 		return true;
783 	}
784 
785 	/* Clone all fragments and reassemble */
786 	skb_queue_walk(list, skb) {
787 		frag = skb_clone(skb, GFP_ATOMIC);
788 		if (!frag)
789 			goto error;
790 		frag->next = NULL;
791 		if (tipc_buf_append(&head, &frag))
792 			break;
793 		if (!head)
794 			goto error;
795 	}
796 	__skb_queue_tail(rcvq, frag);
797 	return true;
798 error:
799 	pr_warn("Failed do clone local mcast rcv buffer\n");
800 	kfree_skb(head);
801 	return false;
802 }
803 
804 bool tipc_msg_pskb_copy(u32 dst, struct sk_buff_head *msg,
805 			struct sk_buff_head *cpy)
806 {
807 	struct sk_buff *skb, *_skb;
808 
809 	skb_queue_walk(msg, skb) {
810 		_skb = pskb_copy(skb, GFP_ATOMIC);
811 		if (!_skb) {
812 			__skb_queue_purge(cpy);
813 			return false;
814 		}
815 		msg_set_destnode(buf_msg(_skb), dst);
816 		__skb_queue_tail(cpy, _skb);
817 	}
818 	return true;
819 }
820 
821 /* tipc_skb_queue_sorted(); sort pkt into list according to sequence number
822  * @list: list to be appended to
823  * @seqno: sequence number of buffer to add
824  * @skb: buffer to add
825  */
826 bool __tipc_skb_queue_sorted(struct sk_buff_head *list, u16 seqno,
827 			     struct sk_buff *skb)
828 {
829 	struct sk_buff *_skb, *tmp;
830 
831 	if (skb_queue_empty(list) || less(seqno, buf_seqno(skb_peek(list)))) {
832 		__skb_queue_head(list, skb);
833 		return true;
834 	}
835 
836 	if (more(seqno, buf_seqno(skb_peek_tail(list)))) {
837 		__skb_queue_tail(list, skb);
838 		return true;
839 	}
840 
841 	skb_queue_walk_safe(list, _skb, tmp) {
842 		if (more(seqno, buf_seqno(_skb)))
843 			continue;
844 		if (seqno == buf_seqno(_skb))
845 			break;
846 		__skb_queue_before(list, _skb, skb);
847 		return true;
848 	}
849 	kfree_skb(skb);
850 	return false;
851 }
852 
853 void tipc_skb_reject(struct net *net, int err, struct sk_buff *skb,
854 		     struct sk_buff_head *xmitq)
855 {
856 	if (tipc_msg_reverse(tipc_own_addr(net), &skb, err))
857 		__skb_queue_tail(xmitq, skb);
858 }
859