Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 851 insertions, 0 deletions

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
new file mode 100644
index 0000000000..5c9fd4791c
--- /dev/null
+++ b/net/tipc/msg.c
@@ -0,0 +1,851 @@
+/*
+ * net/tipc/msg.c: TIPC message header routines
+ *
+ * Copyright (c) 2000-2006, 2014-2015, Ericsson AB
+ * Copyright (c) 2005, 2010-2011, Wind River Systems
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <net/sock.h>
+#include "core.h"
+#include "msg.h"
+#include "addr.h"
+#include "name_table.h"
+#include "crypto.h"
+
+#define BUF_ALIGN(x) ALIGN(x, 4)
+#define MAX_FORWARD_SIZE 1024
+#ifdef CONFIG_TIPC_CRYPTO
+#define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
+#define BUF_OVERHEAD (BUF_HEADROOM + TIPC_AES_GCM_TAG_SIZE)
+#else
+#define BUF_HEADROOM (LL_MAX_HEADER + 48)
+#define BUF_OVERHEAD BUF_HEADROOM
+#endif
+
+const int one_page_mtu = PAGE_SIZE - SKB_DATA_ALIGN(BUF_OVERHEAD) -
+			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+
+/**
+ * tipc_buf_acquire - creates a TIPC message buffer
+ * @size: message size (including TIPC header)
+ * @gfp: memory allocation flags
+ *
+ * Return: a new buffer with data pointers set to the specified size.
+ *
+ * NOTE:
+ * Headroom is reserved to allow prepending of a data link header.
+ * There may also be unrequested tailroom present at the buffer's end.
+ */
+struct sk_buff *tipc_buf_acquire(u32 size, gfp_t gfp)
+{
+	struct sk_buff *skb;
+
+	skb = alloc_skb_fclone(BUF_OVERHEAD + size, gfp);
+	if (skb) {
+		skb_reserve(skb, BUF_HEADROOM);
+		skb_put(skb, size);
+		skb->next = NULL;
+	}
+	return skb;
+}
+
+void tipc_msg_init(u32 own_node, struct tipc_msg *m, u32 user, u32 type,
+		   u32 hsize, u32 dnode)
+{
+	memset(m, 0, hsize);
+	msg_set_version(m);
+	msg_set_user(m, user);
+	msg_set_hdr_sz(m, hsize);
+	msg_set_size(m, hsize);
+	msg_set_prevnode(m, own_node);
+	msg_set_type(m, type);
+	if (hsize > SHORT_H_SIZE) {
+		msg_set_orignode(m, own_node);
+		msg_set_destnode(m, dnode);
+	}
+}
+
+struct sk_buff *tipc_msg_create(uint user, uint type,
+				uint hdr_sz, uint data_sz, u32 dnode,
+				u32 onode, u32 dport, u32 oport, int errcode)
+{
+	struct tipc_msg *msg;
+	struct sk_buff *buf;
+
+	buf = tipc_buf_acquire(hdr_sz + data_sz, GFP_ATOMIC);
+	if (unlikely(!buf))
+		return NULL;
+
+	msg = buf_msg(buf);
+	tipc_msg_init(onode, msg, user, type, hdr_sz, dnode);
+	msg_set_size(msg, hdr_sz + data_sz);
+	msg_set_origport(msg, oport);
+	msg_set_destport(msg, dport);
+	msg_set_errcode(msg, errcode);
+	return buf;
+}
+
+/* tipc_buf_append(): Append a buffer to the fragment list of another buffer
+ * @*headbuf: in:  NULL for first frag, otherwise value returned from prev call
+ *            out: set when successful non-complete reassembly, otherwise NULL
+ * @*buf:     in:  the buffer to append. Always defined
+ *            out: head buf after successful complete reassembly, otherwise NULL
+ * Returns 1 when reassembly complete, otherwise 0
+ */
+int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf)
+{
+	struct sk_buff *head = *headbuf;
+	struct sk_buff *frag = *buf;
+	struct sk_buff *tail = NULL;
+	struct tipc_msg *msg;
+	u32 fragid;
+	int delta;
+	bool headstolen;
+
+	if (!frag)
+		goto err;
+
+	msg = buf_msg(frag);
+	fragid = msg_type(msg);
+	frag->next = NULL;
+	skb_pull(frag, msg_hdr_sz(msg));
+
+	if (fragid == FIRST_FRAGMENT) {
+		if (unlikely(head))
+			goto err;
+		*buf = NULL;
+		if (skb_has_frag_list(frag) && __skb_linearize(frag))
+			goto err;
+		frag = skb_unshare(frag, GFP_ATOMIC);
+		if (unlikely(!frag))
+			goto err;
+		head = *headbuf = frag;
+		TIPC_SKB_CB(head)->tail = NULL;
+		return 0;
+	}
+
+	if (!head)
+		goto err;
+
+	if (skb_try_coalesce(head, frag, &headstolen, &delta)) {
+		kfree_skb_partial(frag, headstolen);
+	} else {
+		tail = TIPC_SKB_CB(head)->tail;
+		if (!skb_has_frag_list(head))
+			skb_shinfo(head)->frag_list = frag;
+		else
+			tail->next = frag;
+		head->truesize += frag->truesize;
+		head->data_len += frag->len;
+		head->len += frag->len;
+		TIPC_SKB_CB(head)->tail = frag;
+	}
+
+	if (fragid == LAST_FRAGMENT) {
+		TIPC_SKB_CB(head)->validated = 0;
+		if (unlikely(!tipc_msg_validate(&head)))
+			goto err;
+		*buf = head;
+		TIPC_SKB_CB(head)->tail = NULL;
+		*headbuf = NULL;
+		return 1;
+	}
+	*buf = NULL;
+	return 0;
+err:
+	kfree_skb(*buf);
+	kfree_skb(*headbuf);
+	*buf = *headbuf = NULL;
+	return 0;
+}
+
+/**
+ * tipc_msg_append(): Append data to tail of an existing buffer queue
+ * @_hdr: header to be used
+ * @m: the data to be appended
+ * @mss: max allowable size of buffer
+ * @dlen: size of data to be appended
+ * @txq: queue to append to
+ *
+ * Return: the number of 1k blocks appended or errno value
+ */
+int tipc_msg_append(struct tipc_msg *_hdr, struct msghdr *m, int dlen,
+		    int mss, struct sk_buff_head *txq)
+{
+	struct sk_buff *skb;
+	int accounted, total, curr;
+	int mlen, cpy, rem = dlen;
+	struct tipc_msg *hdr;
+
+	skb = skb_peek_tail(txq);
+	accounted = skb ? msg_blocks(buf_msg(skb)) : 0;
+	total = accounted;
+
+	do {
+		if (!skb || skb->len >= mss) {
+			skb = tipc_buf_acquire(mss, GFP_KERNEL);
+			if (unlikely(!skb))
+				return -ENOMEM;
+			skb_orphan(skb);
+			skb_trim(skb, MIN_H_SIZE);
+			hdr = buf_msg(skb);
+			skb_copy_to_linear_data(skb, _hdr, MIN_H_SIZE);
+			msg_set_hdr_sz(hdr, MIN_H_SIZE);
+			msg_set_size(hdr, MIN_H_SIZE);
+			__skb_queue_tail(txq, skb);
+			total += 1;
+		}
+		hdr = buf_msg(skb);
+		curr = msg_blocks(hdr);
+		mlen = msg_size(hdr);
+		cpy = min_t(size_t, rem, mss - mlen);
+		if (cpy != copy_from_iter(skb->data + mlen, cpy, &m->msg_iter))
+			return -EFAULT;
+		msg_set_size(hdr, mlen + cpy);
+		skb_put(skb, cpy);
+		rem -= cpy;
+		total += msg_blocks(hdr) - curr;
+	} while (rem > 0);
+	return total - accounted;
+}
+
+/* tipc_msg_validate - validate basic format of received message
+ *
+ * This routine ensures a TIPC message has an acceptable header, and at least
+ * as much data as the header indicates it should.  The routine also ensures
+ * that the entire message header is stored in the main fragment of the message
+ * buffer, to simplify future access to message header fields.
+ *
+ * Note: Having extra info present in the message header or data areas is OK.
+ * TIPC will ignore the excess, under the assumption that it is optional info
+ * introduced by a later release of the protocol.
+ */
+bool tipc_msg_validate(struct sk_buff **_skb)
+{
+	struct sk_buff *skb = *_skb;
+	struct tipc_msg *hdr;
+	int msz, hsz;
+
+	/* Ensure that flow control ratio condition is satisfied */
+	if (unlikely(skb->truesize / buf_roundup_len(skb) >= 4)) {
+		skb = skb_copy_expand(skb, BUF_HEADROOM, 0, GFP_ATOMIC);
+		if (!skb)
+			return false;
+		kfree_skb(*_skb);
+		*_skb = skb;
+	}
+
+	if (unlikely(TIPC_SKB_CB(skb)->validated))
+		return true;
+
+	if (unlikely(!pskb_may_pull(skb, MIN_H_SIZE)))
+		return false;
+
+	hsz = msg_hdr_sz(buf_msg(skb));
+	if (unlikely(hsz < MIN_H_SIZE) || (hsz > MAX_H_SIZE))
+		return false;
+	if (unlikely(!pskb_may_pull(skb, hsz)))
+		return false;
+
+	hdr = buf_msg(skb);
+	if (unlikely(msg_version(hdr) != TIPC_VERSION))
+		return false;
+
+	msz = msg_size(hdr);
+	if (unlikely(msz < hsz))
+		return false;
+	if (unlikely((msz - hsz) > TIPC_MAX_USER_MSG_SIZE))
+		return false;
+	if (unlikely(skb->len < msz))
+		return false;
+
+	TIPC_SKB_CB(skb)->validated = 1;
+	return true;
+}
+
+/**
+ * tipc_msg_fragment - build a fragment skb list for TIPC message
+ *
+ * @skb: TIPC message skb
+ * @hdr: internal msg header to be put on the top of the fragments
+ * @pktmax: max size of a fragment incl. the header
+ * @frags: returned fragment skb list
+ *
+ * Return: 0 if the fragmentation is successful, otherwise: -EINVAL
+ * or -ENOMEM
+ */
+int tipc_msg_fragment(struct sk_buff *skb, const struct tipc_msg *hdr,
+		      int pktmax, struct sk_buff_head *frags)
+{
+	int pktno, nof_fragms, dsz, dmax, eat;
+	struct tipc_msg *_hdr;
+	struct sk_buff *_skb;
+	u8 *data;
+
+	/* Non-linear buffer? */
+	if (skb_linearize(skb))
+		return -ENOMEM;
+
+	data = (u8 *)skb->data;
+	dsz = msg_size(buf_msg(skb));
+	dmax = pktmax - INT_H_SIZE;
+	if (dsz <= dmax || !dmax)
+		return -EINVAL;
+
+	nof_fragms = dsz / dmax + 1;
+	for (pktno = 1; pktno <= nof_fragms; pktno++) {
+		if (pktno < nof_fragms)
+			eat = dmax;
+		else
+			eat = dsz % dmax;
+		/* Allocate a new fragment */
+		_skb = tipc_buf_acquire(INT_H_SIZE + eat, GFP_ATOMIC);
+		if (!_skb)
+			goto error;
+		skb_orphan(_skb);
+		__skb_queue_tail(frags, _skb);
+		/* Copy header & data to the fragment */
+		skb_copy_to_linear_data(_skb, hdr, INT_H_SIZE);
+		skb_copy_to_linear_data_offset(_skb, INT_H_SIZE, data, eat);
+		data += eat;
+		/* Update the fragment's header */
+		_hdr = buf_msg(_skb);
+		msg_set_fragm_no(_hdr, pktno);
+		msg_set_nof_fragms(_hdr, nof_fragms);
+		msg_set_size(_hdr, INT_H_SIZE + eat);
+	}
+	return 0;
+
+error:
+	__skb_queue_purge(frags);
+	__skb_queue_head_init(frags);
+	return -ENOMEM;
+}
+
+/**
+ * tipc_msg_build - create buffer chain containing specified header and data
+ * @mhdr: Message header, to be prepended to data
+ * @m: User message
+ * @offset: buffer offset for fragmented messages (FIXME)
+ * @dsz: Total length of user data
+ * @pktmax: Max packet size that can be used
+ * @list: Buffer or chain of buffers to be returned to caller
+ *
+ * Note that the recursive call we are making here is safe, since it can
+ * logically go only one further level down.
+ *
+ * Return: message data size or errno: -ENOMEM, -EFAULT
+ */
+int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m, int offset,
+		   int dsz, int pktmax, struct sk_buff_head *list)
+{
+	int mhsz = msg_hdr_sz(mhdr);
+	struct tipc_msg pkthdr;
+	int msz = mhsz + dsz;
+	int pktrem = pktmax;
+	struct sk_buff *skb;
+	int drem = dsz;
+	int pktno = 1;
+	char *pktpos;
+	int pktsz;
+	int rc;
+
+	msg_set_size(mhdr, msz);
+
+	/* No fragmentation needed? */
+	if (likely(msz <= pktmax)) {
+		skb = tipc_buf_acquire(msz, GFP_KERNEL);
+
+		/* Fall back to smaller MTU if node local message */
+		if (unlikely(!skb)) {
+			if (pktmax != MAX_MSG_SIZE)
+				return -ENOMEM;
+			rc = tipc_msg_build(mhdr, m, offset, dsz,
+					    one_page_mtu, list);
+			if (rc != dsz)
+				return rc;
+			if (tipc_msg_assemble(list))
+				return dsz;
+			return -ENOMEM;
+		}
+		skb_orphan(skb);
+		__skb_queue_tail(list, skb);
+		skb_copy_to_linear_data(skb, mhdr, mhsz);
+		pktpos = skb->data + mhsz;
+		if (copy_from_iter_full(pktpos, dsz, &m->msg_iter))
+			return dsz;
+		rc = -EFAULT;
+		goto error;
+	}
+
+	/* Prepare reusable fragment header */
+	tipc_msg_init(msg_prevnode(mhdr), &pkthdr, MSG_FRAGMENTER,
+		      FIRST_FRAGMENT, INT_H_SIZE, msg_destnode(mhdr));
+	msg_set_size(&pkthdr, pktmax);
+	msg_set_fragm_no(&pkthdr, pktno);
+	msg_set_importance(&pkthdr, msg_importance(mhdr));
+
+	/* Prepare first fragment */
+	skb = tipc_buf_acquire(pktmax, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+	skb_orphan(skb);
+	__skb_queue_tail(list, skb);
+	pktpos = skb->data;
+	skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
+	pktpos += INT_H_SIZE;
+	pktrem -= INT_H_SIZE;
+	skb_copy_to_linear_data_offset(skb, INT_H_SIZE, mhdr, mhsz);
+	pktpos += mhsz;
+	pktrem -= mhsz;
+
+	do {
+		if (drem < pktrem)
+			pktrem = drem;
+
+		if (!copy_from_iter_full(pktpos, pktrem, &m->msg_iter)) {
+			rc = -EFAULT;
+			goto error;
+		}
+		drem -= pktrem;
+
+		if (!drem)
+			break;
+
+		/* Prepare new fragment: */
+		if (drem < (pktmax - INT_H_SIZE))
+			pktsz = drem + INT_H_SIZE;
+		else
+			pktsz = pktmax;
+		skb = tipc_buf_acquire(pktsz, GFP_KERNEL);
+		if (!skb) {
+			rc = -ENOMEM;
+			goto error;
+		}
+		skb_orphan(skb);
+		__skb_queue_tail(list, skb);
+		msg_set_type(&pkthdr, FRAGMENT);
+		msg_set_size(&pkthdr, pktsz);
+		msg_set_fragm_no(&pkthdr, ++pktno);
+		skb_copy_to_linear_data(skb, &pkthdr, INT_H_SIZE);
+		pktpos = skb->data + INT_H_SIZE;
+		pktrem = pktsz - INT_H_SIZE;
+
+	} while (1);
+	msg_set_type(buf_msg(skb), LAST_FRAGMENT);
+	return dsz;
+error:
+	__skb_queue_purge(list);
+	__skb_queue_head_init(list);
+	return rc;
+}
+
+/**
+ * tipc_msg_bundle - Append contents of a buffer to tail of an existing one
+ * @bskb: the bundle buffer to append to
+ * @msg: message to be appended
+ * @max: max allowable size for the bundle buffer
+ *
+ * Return: "true" if bundling has been performed, otherwise "false"
+ */
+static bool tipc_msg_bundle(struct sk_buff *bskb, struct tipc_msg *msg,
+			    u32 max)
+{
+	struct tipc_msg *bmsg = buf_msg(bskb);
+	u32 msz, bsz, offset, pad;
+
+	msz = msg_size(msg);
+	bsz = msg_size(bmsg);
+	offset = BUF_ALIGN(bsz);
+	pad = offset - bsz;
+
+	if (unlikely(skb_tailroom(bskb) < (pad + msz)))
+		return false;
+	if (unlikely(max < (offset + msz)))
+		return false;
+
+	skb_put(bskb, pad + msz);
+	skb_copy_to_linear_data_offset(bskb, offset, msg, msz);
+	msg_set_size(bmsg, offset + msz);
+	msg_set_msgcnt(bmsg, msg_msgcnt(bmsg) + 1);
+	return true;
+}
+
+/**
+ * tipc_msg_try_bundle - Try to bundle a new message to the last one
+ * @tskb: the last/target message to which the new one will be appended
+ * @skb: the new message skb pointer
+ * @mss: max message size (header inclusive)
+ * @dnode: destination node for the message
+ * @new_bundle: if this call made a new bundle or not
+ *
+ * Return: "true" if the new message skb is potential for bundling this time or
+ * later, in the case a bundling has been done this time, the skb is consumed
+ * (the skb pointer = NULL).
+ * Otherwise, "false" if the skb cannot be bundled at all.
+ */
+bool tipc_msg_try_bundle(struct sk_buff *tskb, struct sk_buff **skb, u32 mss,
+			 u32 dnode, bool *new_bundle)
+{
+	struct tipc_msg *msg, *inner, *outer;
+	u32 tsz;
+
+	/* First, check if the new buffer is suitable for bundling */
+	msg = buf_msg(*skb);
+	if (msg_user(msg) == MSG_FRAGMENTER)
+		return false;
+	if (msg_user(msg) == TUNNEL_PROTOCOL)
+		return false;
+	if (msg_user(msg) == BCAST_PROTOCOL)
+		return false;
+	if (mss <= INT_H_SIZE + msg_size(msg))
+		return false;
+
+	/* Ok, but the last/target buffer can be empty? */
+	if (unlikely(!tskb))
+		return true;
+
+	/* Is it a bundle already? Try to bundle the new message to it */
+	if (msg_user(buf_msg(tskb)) == MSG_BUNDLER) {
+		*new_bundle = false;
+		goto bundle;
+	}
+
+	/* Make a new bundle of the two messages if possible */
+	tsz = msg_size(buf_msg(tskb));
+	if (unlikely(mss < BUF_ALIGN(INT_H_SIZE + tsz) + msg_size(msg)))
+		return true;
+	if (unlikely(pskb_expand_head(tskb, INT_H_SIZE, mss - tsz - INT_H_SIZE,
+				      GFP_ATOMIC)))
+		return true;
+	inner = buf_msg(tskb);
+	skb_push(tskb, INT_H_SIZE);
+	outer = buf_msg(tskb);
+	tipc_msg_init(msg_prevnode(inner), outer, MSG_BUNDLER, 0, INT_H_SIZE,
+		      dnode);
+	msg_set_importance(outer, msg_importance(inner));
+	msg_set_size(outer, INT_H_SIZE + tsz);
+	msg_set_msgcnt(outer, 1);
+	*new_bundle = true;
+
+bundle:
+	if (likely(tipc_msg_bundle(tskb, msg, mss))) {
+		consume_skb(*skb);
+		*skb = NULL;
+	}
+	return true;
+}
+
+/**
+ *  tipc_msg_extract(): extract bundled inner packet from buffer
+ *  @skb: buffer to be extracted from.
+ *  @iskb: extracted inner buffer, to be returned
+ *  @pos: position in outer message of msg to be extracted.
+ *  Returns position of next msg.
+ *  Consumes outer buffer when last packet extracted
+ *  Return: true when there is an extracted buffer, otherwise false
+ */
+bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
+{
+	struct tipc_msg *hdr, *ihdr;
+	int imsz;
+
+	*iskb = NULL;
+	if (unlikely(skb_linearize(skb)))
+		goto none;
+
+	hdr = buf_msg(skb);
+	if (unlikely(*pos > (msg_data_sz(hdr) - MIN_H_SIZE)))
+		goto none;
+
+	ihdr = (struct tipc_msg *)(msg_data(hdr) + *pos);
+	imsz = msg_size(ihdr);
+
+	if ((*pos + imsz) > msg_data_sz(hdr))
+		goto none;
+
+	*iskb = tipc_buf_acquire(imsz, GFP_ATOMIC);
+	if (!*iskb)
+		goto none;
+
+	skb_copy_to_linear_data(*iskb, ihdr, imsz);
+	if (unlikely(!tipc_msg_validate(iskb)))
+		goto none;
+
+	*pos += BUF_ALIGN(imsz);
+	return true;
+none:
+	kfree_skb(skb);
+	kfree_skb(*iskb);
+	*iskb = NULL;
+	return false;
+}
+
+/**
+ * tipc_msg_reverse(): swap source and destination addresses and add error code
+ * @own_node: originating node id for reversed message
+ * @skb:  buffer containing message to be reversed; will be consumed
+ * @err:  error code to be set in message, if any
+ * Replaces consumed buffer with new one when successful
+ * Return: true if success, otherwise false
+ */
+bool tipc_msg_reverse(u32 own_node,  struct sk_buff **skb, int err)
+{
+	struct sk_buff *_skb = *skb;
+	struct tipc_msg *_hdr, *hdr;
+	int hlen, dlen;
+
+	if (skb_linearize(_skb))
+		goto exit;
+	_hdr = buf_msg(_skb);
+	dlen = min_t(uint, msg_data_sz(_hdr), MAX_FORWARD_SIZE);
+	hlen = msg_hdr_sz(_hdr);
+
+	if (msg_dest_droppable(_hdr))
+		goto exit;
+	if (msg_errcode(_hdr))
+		goto exit;
+
+	/* Never return SHORT header */
+	if (hlen == SHORT_H_SIZE)
+		hlen = BASIC_H_SIZE;
+
+	/* Don't return data along with SYN+, - sender has a clone */
+	if (msg_is_syn(_hdr) && err == TIPC_ERR_OVERLOAD)
+		dlen = 0;
+
+	/* Allocate new buffer to return */
+	*skb = tipc_buf_acquire(hlen + dlen, GFP_ATOMIC);
+	if (!*skb)
+		goto exit;
+	memcpy((*skb)->data, _skb->data, msg_hdr_sz(_hdr));
+	memcpy((*skb)->data + hlen, msg_data(_hdr), dlen);
+
+	/* Build reverse header in new buffer */
+	hdr = buf_msg(*skb);
+	msg_set_hdr_sz(hdr, hlen);
+	msg_set_errcode(hdr, err);
+	msg_set_non_seq(hdr, 0);
+	msg_set_origport(hdr, msg_destport(_hdr));
+	msg_set_destport(hdr, msg_origport(_hdr));
+	msg_set_destnode(hdr, msg_prevnode(_hdr));
+	msg_set_prevnode(hdr, own_node);
+	msg_set_orignode(hdr, own_node);
+	msg_set_size(hdr, hlen + dlen);
+	skb_orphan(_skb);
+	kfree_skb(_skb);
+	return true;
+exit:
+	kfree_skb(_skb);
+	*skb = NULL;
+	return false;
+}
+
+bool tipc_msg_skb_clone(struct sk_buff_head *msg, struct sk_buff_head *cpy)
+{
+	struct sk_buff *skb, *_skb;
+
+	skb_queue_walk(msg, skb) {
+		_skb = skb_clone(skb, GFP_ATOMIC);
+		if (!_skb) {
+			__skb_queue_purge(cpy);
+			pr_err_ratelimited("Failed to clone buffer chain\n");
+			return false;
+		}
+		__skb_queue_tail(cpy, _skb);
+	}
+	return true;
+}
+
+/**
+ * tipc_msg_lookup_dest(): try to find new destination for named message
+ * @net: pointer to associated network namespace
+ * @skb: the buffer containing the message.
+ * @err: error code to be used by caller if lookup fails
+ * Does not consume buffer
+ * Return: true if a destination is found, false otherwise
+ */
+bool tipc_msg_lookup_dest(struct net *net, struct sk_buff *skb, int *err)
+{
+	struct tipc_msg *msg = buf_msg(skb);
+	u32 scope = msg_lookup_scope(msg);
+	u32 self = tipc_own_addr(net);
+	u32 inst = msg_nameinst(msg);
+	struct tipc_socket_addr sk;
+	struct tipc_uaddr ua;
+
+	if (!msg_isdata(msg))
+		return false;
+	if (!msg_named(msg))
+		return false;
+	if (msg_errcode(msg))
+		return false;
+	*err = TIPC_ERR_NO_NAME;
+	if (skb_linearize(skb))
+		return false;
+	msg = buf_msg(skb);
+	if (msg_reroute_cnt(msg))
+		return false;
+	tipc_uaddr(&ua, TIPC_SERVICE_RANGE, scope,
+		   msg_nametype(msg), inst, inst);
+	sk.node = tipc_scope2node(net, scope);
+	if (!tipc_nametbl_lookup_anycast(net, &ua, &sk))
+		return false;
+	msg_incr_reroute_cnt(msg);
+	if (sk.node != self)
+		msg_set_prevnode(msg, self);
+	msg_set_destnode(msg, sk.node);
+	msg_set_destport(msg, sk.ref);
+	*err = TIPC_OK;
+
+	return true;
+}
+
+/* tipc_msg_assemble() - assemble chain of fragments into one message
+ */
+bool tipc_msg_assemble(struct sk_buff_head *list)
+{
+	struct sk_buff *skb, *tmp = NULL;
+
+	if (skb_queue_len(list) == 1)
+		return true;
+
+	while ((skb = __skb_dequeue(list))) {
+		skb->next = NULL;
+		if (tipc_buf_append(&tmp, &skb)) {
+			__skb_queue_tail(list, skb);
+			return true;
+		}
+		if (!tmp)
+			break;
+	}
+	__skb_queue_purge(list);
+	__skb_queue_head_init(list);
+	pr_warn("Failed do assemble buffer\n");
+	return false;
+}
+
+/* tipc_msg_reassemble() - clone a buffer chain of fragments and
+ *                         reassemble the clones into one message
+ */
+bool tipc_msg_reassemble(struct sk_buff_head *list, struct sk_buff_head *rcvq)
+{
+	struct sk_buff *skb, *_skb;
+	struct sk_buff *frag = NULL;
+	struct sk_buff *head = NULL;
+	int hdr_len;
+
+	/* Copy header if single buffer */
+	if (skb_queue_len(list) == 1) {
+		skb = skb_peek(list);
+		hdr_len = skb_headroom(skb) + msg_hdr_sz(buf_msg(skb));
+		_skb = __pskb_copy(skb, hdr_len, GFP_ATOMIC);
+		if (!_skb)
+			return false;
+		__skb_queue_tail(rcvq, _skb);
+		return true;
+	}
+
+	/* Clone all fragments and reassemble */
+	skb_queue_walk(list, skb) {
+		frag = skb_clone(skb, GFP_ATOMIC);
+		if (!frag)
+			goto error;
+		frag->next = NULL;
+		if (tipc_buf_append(&head, &frag))
+			break;
+		if (!head)
+			goto error;
+	}
+	__skb_queue_tail(rcvq, frag);
+	return true;
+error:
+	pr_warn("Failed do clone local mcast rcv buffer\n");
+	kfree_skb(head);
+	return false;
+}
+
+bool tipc_msg_pskb_copy(u32 dst, struct sk_buff_head *msg,
+			struct sk_buff_head *cpy)
+{
+	struct sk_buff *skb, *_skb;
+
+	skb_queue_walk(msg, skb) {
+		_skb = pskb_copy(skb, GFP_ATOMIC);
+		if (!_skb) {
+			__skb_queue_purge(cpy);
+			return false;
+		}
+		msg_set_destnode(buf_msg(_skb), dst);
+		__skb_queue_tail(cpy, _skb);
+	}
+	return true;
+}
+
+/* tipc_skb_queue_sorted(); sort pkt into list according to sequence number
+ * @list: list to be appended to
+ * @seqno: sequence number of buffer to add
+ * @skb: buffer to add
+ */
+bool __tipc_skb_queue_sorted(struct sk_buff_head *list, u16 seqno,
+			     struct sk_buff *skb)
+{
+	struct sk_buff *_skb, *tmp;
+
+	if (skb_queue_empty(list) || less(seqno, buf_seqno(skb_peek(list)))) {
+		__skb_queue_head(list, skb);
+		return true;
+	}
+
+	if (more(seqno, buf_seqno(skb_peek_tail(list)))) {
+		__skb_queue_tail(list, skb);
+		return true;
+	}
+
+	skb_queue_walk_safe(list, _skb, tmp) {
+		if (more(seqno, buf_seqno(_skb)))
+			continue;
+		if (seqno == buf_seqno(_skb))
+			break;
+		__skb_queue_before(list, _skb, skb);
+		return true;
+	}
+	kfree_skb(skb);
+	return false;
+}
+
+void tipc_skb_reject(struct net *net, int err, struct sk_buff *skb,
+		     struct sk_buff_head *xmitq)
+{
+	if (tipc_msg_reverse(tipc_own_addr(net), &skb, err))
+		__skb_queue_tail(xmitq, skb);
+}