Merge tag 'exfat-for-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/linki...

[mirror_ubuntu-jammy-kernel.git] / net / tipc / msg.c

/*
 * 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 MAX_FORWARD_SIZE 1024
#ifdef CONFIG_TIPC_CRYPTO
#define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
#define BUF_TAILROOM (TIPC_AES_GCM_TAG_SIZE)
#else
#define BUF_HEADROOM (LL_MAX_HEADER + 48)
#define BUF_TAILROOM 16
#endif

static unsigned int align(unsigned int i)
{
        return (i + 3) & ~3u;
}

/**
 * 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;
#ifdef CONFIG_TIPC_CRYPTO
        unsigned int buf_size = (BUF_HEADROOM + size + BUF_TAILROOM + 3) & ~3u;
#else
        unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;
#endif

        skb = alloc_skb_fclone(buf_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;
                frag = skb_unshare(frag, GFP_ATOMIC);
                if (unlikely(!frag))
                        goto err;
                head = *headbuf = frag;
                TIPC_SKB_CB(head)->tail = NULL;
                if (skb_is_nonlinear(head)) {
                        skb_walk_frags(head, tail) {
                                TIPC_SKB_CB(head)->tail = tail;
                        }
                } else {
                        skb_frag_list_init(head);
                }
                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, FB_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 = 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 < 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 += 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 dport, dnode;
        u32 onode = tipc_own_addr(net);

        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;
        dnode = tipc_scope2node(net, msg_lookup_scope(msg));
        dport = tipc_nametbl_translate(net, msg_nametype(msg),
                                       msg_nameinst(msg), &dnode);
        if (!dport)
                return false;
        msg_incr_reroute_cnt(msg);
        if (dnode != onode)
                msg_set_prevnode(msg, onode);
        msg_set_destnode(msg, dnode);
        msg_set_destport(msg, dport);
        *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);
}