ClabureDB: Classified Bug-Reports Database

   /*
    *        IPv6 output functions
    *        Linux INET6 implementation
    *
    *        Authors:
    *        Pedro Roque                <roque@di.fc.ul.pt>
    *
    *        Based on linux/net/ipv4/ip_output.c
    *
   *        This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   *
   *        Changes:
   *        A.N.Kuznetsov        :        airthmetics in fragmentation.
   *                                extension headers are implemented.
   *                                route changes now work.
   *                                ip6_forward does not confuse sniffers.
   *                                etc.
   *
   *      H. von Brand    :       Added missing #include <linux/string.h>
   *        Imran Patel        :         frag id should be in NBO
   *      Kazunori MIYAZAWA @USAGI
   *                        :       add ip6_append_data and related functions
   *                                for datagram xmit
   */
  
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/socket.h>
  #include <linux/net.h>
  #include <linux/netdevice.h>
  #include <linux/if_arp.h>
  #include <linux/in6.h>
  #include <linux/tcp.h>
  #include <linux/route.h>
  #include <linux/module.h>
  
  #include <linux/netfilter.h>
  #include <linux/netfilter_ipv6.h>
  
  #include <net/sock.h>
  #include <net/snmp.h>
  
  #include <net/ipv6.h>
  #include <net/ndisc.h>
  #include <net/protocol.h>
  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  #include <net/rawv6.h>
  #include <net/icmp.h>
  #include <net/xfrm.h>
  #include <net/checksum.h>
  #include <linux/mroute6.h>
  
  static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
  
  static __inline__ void ipv6_select_ident(struct sk_buff *skb, struct frag_hdr *fhdr)
  {
          static u32 ipv6_fragmentation_id = 1;
          static DEFINE_SPINLOCK(ip6_id_lock);
  
          spin_lock_bh(&ip6_id_lock);
          fhdr->identification = htonl(ipv6_fragmentation_id);
          if (++ipv6_fragmentation_id == 0)
                  ipv6_fragmentation_id = 1;
          spin_unlock_bh(&ip6_id_lock);
  }
  
  int __ip6_local_out(struct sk_buff *skb)
  {
          int len;
  
          len = skb->len - sizeof(struct ipv6hdr);
          if (len > IPV6_MAXPLEN)
                  len = 0;
          ipv6_hdr(skb)->payload_len = htons(len);
  
          return nf_hook(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, skb->dst->dev,
                         dst_output);
  }
  
  int ip6_local_out(struct sk_buff *skb)
  {
          int err;
  
          err = __ip6_local_out(skb);
          if (likely(err == 1))
                  err = dst_output(skb);
  
          return err;
  }
  EXPORT_SYMBOL_GPL(ip6_local_out);
  
  static int ip6_output_finish(struct sk_buff *skb)
  {
          struct dst_entry *dst = skb->dst;
 
         if (dst->hh)
                 return neigh_hh_output(dst->hh, skb);
         else if (dst->neighbour)
                 return dst->neighbour->output(skb);
 
         IP6_INC_STATS_BH(dev_net(dst->dev),
                          ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
         kfree_skb(skb);
         return -EINVAL;
 
 }
 
 /* dev_loopback_xmit for use with netfilter. */
 static int ip6_dev_loopback_xmit(struct sk_buff *newskb)
 {
         skb_reset_mac_header(newskb);
         __skb_pull(newskb, skb_network_offset(newskb));
         newskb->pkt_type = PACKET_LOOPBACK;
         newskb->ip_summed = CHECKSUM_UNNECESSARY;
         WARN_ON(!newskb->dst);
 
         netif_rx(newskb);
         return 0;
 }
 
 
 static int ip6_output2(struct sk_buff *skb)
 {
         struct dst_entry *dst = skb->dst;
         struct net_device *dev = dst->dev;
 
         skb->protocol = htons(ETH_P_IPV6);
         skb->dev = dev;
 
         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
                 struct ipv6_pinfo* np = skb->sk ? inet6_sk(skb->sk) : NULL;
                 struct inet6_dev *idev = ip6_dst_idev(skb->dst);
 
                 if (!(dev->flags & IFF_LOOPBACK) && (!np || np->mc_loop) &&
                     ((mroute6_socket && !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
                      ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
                                          &ipv6_hdr(skb)->saddr))) {
                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 
                         /* Do not check for IFF_ALLMULTI; multicast routing
                            is not supported in any case.
                          */
                         if (newskb)
                                 NF_HOOK(PF_INET6, NF_INET_POST_ROUTING, newskb,
                                         NULL, newskb->dev,
                                         ip6_dev_loopback_xmit);
 
                         if (ipv6_hdr(skb)->hop_limit == 0) {
                                 IP6_INC_STATS(dev_net(dev), idev,
                                               IPSTATS_MIB_OUTDISCARDS);
                                 kfree_skb(skb);
                                 return 0;
                         }
                 }
 
                 IP6_INC_STATS(dev_net(dev), idev, IPSTATS_MIB_OUTMCASTPKTS);
         }
 
         return NF_HOOK(PF_INET6, NF_INET_POST_ROUTING, skb, NULL, skb->dev,
                        ip6_output_finish);
 }
 
 static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
 {
         struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
 
         return (np && np->pmtudisc == IPV6_PMTUDISC_PROBE) ?
                skb->dst->dev->mtu : dst_mtu(skb->dst);
 }
 
 int ip6_output(struct sk_buff *skb)
 {
         struct inet6_dev *idev = ip6_dst_idev(skb->dst);
         if (unlikely(idev->cnf.disable_ipv6)) {
                 IP6_INC_STATS(dev_net(skb->dst->dev), idev,
                               IPSTATS_MIB_OUTDISCARDS);
                 kfree_skb(skb);
                 return 0;
         }
 
         if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
                                 dst_allfrag(skb->dst))
                 return ip6_fragment(skb, ip6_output2);
         else
                 return ip6_output2(skb);
 }
 
 /*
  *        xmit an sk_buff (used by TCP)
  */
 
 int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
              struct ipv6_txoptions *opt, int ipfragok)
 {
         struct net *net = sock_net(sk);
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct in6_addr *first_hop = &fl->fl6_dst;
         struct dst_entry *dst = skb->dst;
         struct ipv6hdr *hdr;
         u8  proto = fl->proto;
         int seg_len = skb->len;
         int hlimit, tclass;
         u32 mtu;
 
         if (opt) {
                 unsigned int head_room;
 
                 /* First: exthdrs may take lots of space (~8K for now)
                    MAX_HEADER is not enough.
                  */
                 head_room = opt->opt_nflen + opt->opt_flen;
                 seg_len += head_room;
                 head_room += sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
 
                 if (skb_headroom(skb) < head_room) {
                         struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
                         if (skb2 == NULL) {
                                 IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                                               IPSTATS_MIB_OUTDISCARDS);
                                 kfree_skb(skb);
                                 return -ENOBUFS;
                         }
                         kfree_skb(skb);
                         skb = skb2;
                         if (sk)
                                 skb_set_owner_w(skb, sk);
                 }
                 if (opt->opt_flen)
                         ipv6_push_frag_opts(skb, opt, &proto);
                 if (opt->opt_nflen)
                         ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop);
         }
 
         skb_push(skb, sizeof(struct ipv6hdr));
         skb_reset_network_header(skb);
         hdr = ipv6_hdr(skb);
 
         /* Allow local fragmentation. */
         if (ipfragok)
                 skb->local_df = 1;
 
         /*
          *        Fill in the IPv6 header
          */
 
         hlimit = -1;
         if (np)
                 hlimit = np->hop_limit;
         if (hlimit < 0)
                 hlimit = ip6_dst_hoplimit(dst);
 
         tclass = -1;
         if (np)
                 tclass = np->tclass;
         if (tclass < 0)
                 tclass = 0;
 
         *(__be32 *)hdr = htonl(0x60000000 | (tclass << 20)) | fl->fl6_flowlabel;
 
         hdr->payload_len = htons(seg_len);
         hdr->nexthdr = proto;
         hdr->hop_limit = hlimit;
 
         ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
         ipv6_addr_copy(&hdr->daddr, first_hop);
 
         skb->priority = sk->sk_priority;
         skb->mark = sk->sk_mark;
 
         mtu = dst_mtu(dst);
         if ((skb->len <= mtu) || skb->local_df || skb_is_gso(skb)) {
                 IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                               IPSTATS_MIB_OUTREQUESTS);
                 return NF_HOOK(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, dst->dev,
                                 dst_output);
         }
 
         if (net_ratelimit())
                 printk(KERN_DEBUG "IPv6: sending pkt_too_big to self\n");
         skb->dev = dst->dev;
         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
         IP6_INC_STATS(net, ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
         kfree_skb(skb);
         return -EMSGSIZE;
 }
 
 EXPORT_SYMBOL(ip6_xmit);
 
 /*
  *        To avoid extra problems ND packets are send through this
  *        routine. It's code duplication but I really want to avoid
  *        extra checks since ipv6_build_header is used by TCP (which
  *        is for us performance critical)
  */
 
 int ip6_nd_hdr(struct sock *sk, struct sk_buff *skb, struct net_device *dev,
                const struct in6_addr *saddr, const struct in6_addr *daddr,
                int proto, int len)
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct ipv6hdr *hdr;
         int totlen;
 
         skb->protocol = htons(ETH_P_IPV6);
         skb->dev = dev;
 
         totlen = len + sizeof(struct ipv6hdr);
 
         skb_reset_network_header(skb);
         skb_put(skb, sizeof(struct ipv6hdr));
         hdr = ipv6_hdr(skb);
 
         *(__be32*)hdr = htonl(0x60000000);
 
         hdr->payload_len = htons(len);
         hdr->nexthdr = proto;
         hdr->hop_limit = np->hop_limit;
 
         ipv6_addr_copy(&hdr->saddr, saddr);
         ipv6_addr_copy(&hdr->daddr, daddr);
 
         return 0;
 }
 
 static int ip6_call_ra_chain(struct sk_buff *skb, int sel)
 {
         struct ip6_ra_chain *ra;
         struct sock *last = NULL;
 
         read_lock(&ip6_ra_lock);
         for (ra = ip6_ra_chain; ra; ra = ra->next) {
                 struct sock *sk = ra->sk;
                 if (sk && ra->sel == sel &&
                     (!sk->sk_bound_dev_if ||
                      sk->sk_bound_dev_if == skb->dev->ifindex)) {
                         if (last) {
                                 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
                                 if (skb2)
                                         rawv6_rcv(last, skb2);
                         }
                         last = sk;
                 }
         }
 
         if (last) {
                 rawv6_rcv(last, skb);
                 read_unlock(&ip6_ra_lock);
                 return 1;
         }
         read_unlock(&ip6_ra_lock);
         return 0;
 }
 
 static int ip6_forward_proxy_check(struct sk_buff *skb)
 {
         struct ipv6hdr *hdr = ipv6_hdr(skb);
         u8 nexthdr = hdr->nexthdr;
         int offset;
 
         if (ipv6_ext_hdr(nexthdr)) {
                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), &nexthdr);
                 if (offset < 0)
                         return 0;
         } else
                 offset = sizeof(struct ipv6hdr);
 
         if (nexthdr == IPPROTO_ICMPV6) {
                 struct icmp6hdr *icmp6;
 
                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
                                          offset + 1 - skb->data)))
                         return 0;
 
                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 
                 switch (icmp6->icmp6_type) {
                 case NDISC_ROUTER_SOLICITATION:
                 case NDISC_ROUTER_ADVERTISEMENT:
                 case NDISC_NEIGHBOUR_SOLICITATION:
                 case NDISC_NEIGHBOUR_ADVERTISEMENT:
                 case NDISC_REDIRECT:
                         /* For reaction involving unicast neighbor discovery
                          * message destined to the proxied address, pass it to
                          * input function.
                          */
                         return 1;
                 default:
                         break;
                 }
         }
 
         /*
          * The proxying router can't forward traffic sent to a link-local
          * address, so signal the sender and discard the packet. This
          * behavior is clarified by the MIPv6 specification.
          */
         if (ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) {
                 dst_link_failure(skb);
                 return -1;
         }
 
         return 0;
 }
 
 static inline int ip6_forward_finish(struct sk_buff *skb)
 {
         return dst_output(skb);
 }
 
 int ip6_forward(struct sk_buff *skb)
 {
         struct dst_entry *dst = skb->dst;
         struct ipv6hdr *hdr = ipv6_hdr(skb);
         struct inet6_skb_parm *opt = IP6CB(skb);
         struct net *net = dev_net(dst->dev);
 
         if (net->ipv6.devconf_all->forwarding == 0)
                 goto error;
 
         if (skb_warn_if_lro(skb))
                 goto drop;
 
         if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
                 goto drop;
         }
 
         skb_forward_csum(skb);
 
         /*
          *        We DO NOT make any processing on
          *        RA packets, pushing them to user level AS IS
          *        without ane WARRANTY that application will be able
          *        to interpret them. The reason is that we
          *        cannot make anything clever here.
          *
          *        We are not end-node, so that if packet contains
          *        AH/ESP, we cannot make anything.
          *        Defragmentation also would be mistake, RA packets
          *        cannot be fragmented, because there is no warranty
          *        that different fragments will go along one path. --ANK
          */
         if (opt->ra) {
                 u8 *ptr = skb_network_header(skb) + opt->ra;
                 if (ip6_call_ra_chain(skb, (ptr[2]<<8) + ptr[3]))
                         return 0;
         }
 
         /*
          *        check and decrement ttl
          */
         if (hdr->hop_limit <= 1) {
                 /* Force OUTPUT device used as source address */
                 skb->dev = dst->dev;
                 icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
                             0, skb->dev);
                 IP6_INC_STATS_BH(net,
                                  ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 
                 kfree_skb(skb);
                 return -ETIMEDOUT;
         }
 
         /* XXX: idev->cnf.proxy_ndp? */
         if (net->ipv6.devconf_all->proxy_ndp &&
             pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
                 int proxied = ip6_forward_proxy_check(skb);
                 if (proxied > 0)
                         return ip6_input(skb);
                 else if (proxied < 0) {
                         IP6_INC_STATS(net, ip6_dst_idev(dst),
                                       IPSTATS_MIB_INDISCARDS);
                         goto drop;
                 }
         }
 
         if (!xfrm6_route_forward(skb)) {
                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
                 goto drop;
         }
         dst = skb->dst;
 
         /* IPv6 specs say nothing about it, but it is clear that we cannot
            send redirects to source routed frames.
            We don't send redirects to frames decapsulated from IPsec.
          */
         if (skb->dev == dst->dev && dst->neighbour && opt->srcrt == 0 &&
             !skb->sp) {
                 struct in6_addr *target = NULL;
                 struct rt6_info *rt;
                 struct neighbour *n = dst->neighbour;
 
                 /*
                  *        incoming and outgoing devices are the same
                  *        send a redirect.
                  */
 
                 rt = (struct rt6_info *) dst;
                 if ((rt->rt6i_flags & RTF_GATEWAY))
                         target = (struct in6_addr*)&n->primary_key;
                 else
                         target = &hdr->daddr;
 
                 /* Limit redirects both by destination (here)
                    and by source (inside ndisc_send_redirect)
                  */
                 if (xrlim_allow(dst, 1*HZ))
                         ndisc_send_redirect(skb, n, target);
         } else {
                 int addrtype = ipv6_addr_type(&hdr->saddr);
 
                 /* This check is security critical. */
                 if (addrtype == IPV6_ADDR_ANY ||
                     addrtype & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LOOPBACK))
                         goto error;
                 if (addrtype & IPV6_ADDR_LINKLOCAL) {
                         icmpv6_send(skb, ICMPV6_DEST_UNREACH,
                                 ICMPV6_NOT_NEIGHBOUR, 0, skb->dev);
                         goto error;
                 }
         }
 
         if (skb->len > dst_mtu(dst)) {
                 /* Again, force OUTPUT device used as source address */
                 skb->dev = dst->dev;
                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, dst_mtu(dst), skb->dev);
                 IP6_INC_STATS_BH(net,
                                  ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS);
                 IP6_INC_STATS_BH(net,
                                  ip6_dst_idev(dst), IPSTATS_MIB_FRAGFAILS);
                 kfree_skb(skb);
                 return -EMSGSIZE;
         }
 
         if (skb_cow(skb, dst->dev->hard_header_len)) {
                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
                 goto drop;
         }
 
         hdr = ipv6_hdr(skb);
 
         /* Mangling hops number delayed to point after skb COW */
 
         hdr->hop_limit--;
 
         IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
         return NF_HOOK(PF_INET6, NF_INET_FORWARD, skb, skb->dev, dst->dev,
                        ip6_forward_finish);
 
 error:
         IP6_INC_STATS_BH(net, ip6_dst_idev(dst), IPSTATS_MIB_INADDRERRORS);
 drop:
         kfree_skb(skb);
         return -EINVAL;
 }
 
 static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 {
         to->pkt_type = from->pkt_type;
         to->priority = from->priority;
         to->protocol = from->protocol;
         dst_release(to->dst);
         to->dst = dst_clone(from->dst);
         to->dev = from->dev;
         to->mark = from->mark;
 
 #ifdef CONFIG_NET_SCHED
         to->tc_index = from->tc_index;
 #endif
         nf_copy(to, from);
 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
         to->nf_trace = from->nf_trace;
 #endif
         skb_copy_secmark(to, from);
 }
 
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 {
         u16 offset = sizeof(struct ipv6hdr);
         struct ipv6_opt_hdr *exthdr =
                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
         unsigned int packet_len = skb->tail - skb->network_header;
         int found_rhdr = 0;
         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 
         while (offset + 1 <= packet_len) {
 
                 switch (**nexthdr) {
 
                 case NEXTHDR_HOP:
                         break;
                 case NEXTHDR_ROUTING:
                         found_rhdr = 1;
                         break;
                 case NEXTHDR_DEST:
 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
                                 break;
 #endif
                         if (found_rhdr)
                                 return offset;
                         break;
                 default :
                         return offset;
                 }
 
                 offset += ipv6_optlen(exthdr);
                 *nexthdr = &exthdr->nexthdr;
                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
                                                  offset);
         }
 
         return offset;
 }
 
 static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 {
         struct sk_buff *frag;
         struct rt6_info *rt = (struct rt6_info*)skb->dst;
         struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
         struct ipv6hdr *tmp_hdr;
         struct frag_hdr *fh;
         unsigned int mtu, hlen, left, len;
         __be32 frag_id = 0;
         int ptr, offset = 0, err=0;
         u8 *prevhdr, nexthdr = 0;
         struct net *net = dev_net(skb->dst->dev);
 
         hlen = ip6_find_1stfragopt(skb, &prevhdr);
         nexthdr = *prevhdr;
 
         mtu = ip6_skb_dst_mtu(skb);
 
         /* We must not fragment if the socket is set to force MTU discovery
          * or if the skb it not generated by a local socket.  (This last
          * check should be redundant, but it's free.)
          */
         if (!skb->local_df) {
                 skb->dev = skb->dst->dev;
                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
                 IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                               IPSTATS_MIB_FRAGFAILS);
                 kfree_skb(skb);
                 return -EMSGSIZE;
         }
 
         if (np && np->frag_size < mtu) {
                 if (np->frag_size)
                         mtu = np->frag_size;
         }
         mtu -= hlen + sizeof(struct frag_hdr);
 
         if (skb_shinfo(skb)->frag_list) {
                 int first_len = skb_pagelen(skb);
                 int truesizes = 0;
 
                 if (first_len - hlen > mtu ||
                     ((first_len - hlen) & 7) ||
                     skb_cloned(skb))
                         goto slow_path;
 
                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
                         /* Correct geometry. */
                         if (frag->len > mtu ||
                             ((frag->len & 7) && frag->next) ||
                             skb_headroom(frag) < hlen)
                             goto slow_path;
 
                         /* Partially cloned skb? */
                         if (skb_shared(frag))
                                 goto slow_path;
 
                         BUG_ON(frag->sk);
                         if (skb->sk) {
                                 sock_hold(skb->sk);
                                 frag->sk = skb->sk;
                                 frag->destructor = sock_wfree;
                                 truesizes += frag->truesize;
                         }
                 }
 
                 err = 0;
                 offset = 0;
                 frag = skb_shinfo(skb)->frag_list;
                 skb_shinfo(skb)->frag_list = NULL;
                 /* BUILD HEADER */
 
                 *prevhdr = NEXTHDR_FRAGMENT;
                 tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
                 if (!tmp_hdr) {
                         IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                                       IPSTATS_MIB_FRAGFAILS);
                         return -ENOMEM;
                 }
 
                 __skb_pull(skb, hlen);
                 fh = (struct frag_hdr*)__skb_push(skb, sizeof(struct frag_hdr));
                 __skb_push(skb, hlen);
                 skb_reset_network_header(skb);
                 memcpy(skb_network_header(skb), tmp_hdr, hlen);
 
                 ipv6_select_ident(skb, fh);
                 fh->nexthdr = nexthdr;
                 fh->reserved = 0;
                 fh->frag_off = htons(IP6_MF);
                 frag_id = fh->identification;
 
                 first_len = skb_pagelen(skb);
                 skb->data_len = first_len - skb_headlen(skb);
                 skb->truesize -= truesizes;
                 skb->len = first_len;
                 ipv6_hdr(skb)->payload_len = htons(first_len -
                                                    sizeof(struct ipv6hdr));
 
                 dst_hold(&rt->u.dst);
 
                 for (;;) {
                         /* Prepare header of the next frame,
                          * before previous one went down. */
                         if (frag) {
                                 frag->ip_summed = CHECKSUM_NONE;
                                 skb_reset_transport_header(frag);
                                 fh = (struct frag_hdr*)__skb_push(frag, sizeof(struct frag_hdr));
                                 __skb_push(frag, hlen);
                                 skb_reset_network_header(frag);
                                 memcpy(skb_network_header(frag), tmp_hdr,
                                        hlen);
                                 offset += skb->len - hlen - sizeof(struct frag_hdr);
                                 fh->nexthdr = nexthdr;
                                 fh->reserved = 0;
                                 fh->frag_off = htons(offset);
                                 if (frag->next != NULL)
                                         fh->frag_off |= htons(IP6_MF);
                                 fh->identification = frag_id;
                                 ipv6_hdr(frag)->payload_len =
                                                 htons(frag->len -
                                                       sizeof(struct ipv6hdr));
                                 ip6_copy_metadata(frag, skb);
                         }
 
                         err = output(skb);
                         if(!err)
                                 IP6_INC_STATS(net, ip6_dst_idev(&rt->u.dst),
                                               IPSTATS_MIB_FRAGCREATES);
 
                         if (err || !frag)
                                 break;
 
                         skb = frag;
                         frag = skb->next;
                         skb->next = NULL;
                 }
 
                 kfree(tmp_hdr);
 
                 if (err == 0) {
                         IP6_INC_STATS(net, ip6_dst_idev(&rt->u.dst),
                                       IPSTATS_MIB_FRAGOKS);
                         dst_release(&rt->u.dst);
                         return 0;
                 }
 
                 while (frag) {
                         skb = frag->next;
                         kfree_skb(frag);
                         frag = skb;
                 }
 
                 IP6_INC_STATS(net, ip6_dst_idev(&rt->u.dst),
                               IPSTATS_MIB_FRAGFAILS);
                 dst_release(&rt->u.dst);
                 return err;
         }
 
 slow_path:
         left = skb->len - hlen;                /* Space per frame */
         ptr = hlen;                        /* Where to start from */
 
         /*
          *        Fragment the datagram.
          */
 
         *prevhdr = NEXTHDR_FRAGMENT;
 
         /*
          *        Keep copying data until we run out.
          */
         while(left > 0)        {
                 len = left;
                 /* IF: it doesn't fit, use 'mtu' - the data space left */
                 if (len > mtu)
                         len = mtu;
                 /* IF: we are not sending upto and including the packet end
                    then align the next start on an eight byte boundary */
                 if (len < left)        {
                         len &= ~7;
                 }
                 /*
                  *        Allocate buffer.
                  */
 
                 if ((frag = alloc_skb(len+hlen+sizeof(struct frag_hdr)+LL_ALLOCATED_SPACE(rt->u.dst.dev), GFP_ATOMIC)) == NULL) {
                         NETDEBUG(KERN_INFO "IPv6: frag: no memory for new fragment!\n");
                         IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                                       IPSTATS_MIB_FRAGFAILS);
                         err = -ENOMEM;
                         goto fail;
                 }
 
                 /*
                  *        Set up data on packet
                  */
 
                 ip6_copy_metadata(frag, skb);
                 skb_reserve(frag, LL_RESERVED_SPACE(rt->u.dst.dev));
                 skb_put(frag, len + hlen + sizeof(struct frag_hdr));
                 skb_reset_network_header(frag);
                 fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
                 frag->transport_header = (frag->network_header + hlen +
                                           sizeof(struct frag_hdr));
 
                 /*
                  *        Charge the memory for the fragment to any owner
                  *        it might possess
                  */
                 if (skb->sk)
                         skb_set_owner_w(frag, skb->sk);
 
                 /*
                  *        Copy the packet header into the new buffer.
                  */
                 skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);
 
                 /*
                  *        Build fragment header.
                  */
                 fh->nexthdr = nexthdr;
                 fh->reserved = 0;
                 if (!frag_id) {
                         ipv6_select_ident(skb, fh);
                         frag_id = fh->identification;
                 } else
                         fh->identification = frag_id;
 
                 /*
                  *        Copy a block of the IP datagram.
                  */
                 if (skb_copy_bits(skb, ptr, skb_transport_header(frag), len))
                         BUG();
                 left -= len;
 
                 fh->frag_off = htons(offset);
                 if (left > 0)
                         fh->frag_off |= htons(IP6_MF);
                 ipv6_hdr(frag)->payload_len = htons(frag->len -
                                                     sizeof(struct ipv6hdr));
 
                 ptr += len;
                 offset += len;
 
                 /*
                  *        Put this fragment into the sending queue.
                  */
                 err = output(frag);
                 if (err)
                         goto fail;
 
                 IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                               IPSTATS_MIB_FRAGCREATES);
         }
         IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                       IPSTATS_MIB_FRAGOKS);
         kfree_skb(skb);
         return err;
 
 fail:
         IP6_INC_STATS(net, ip6_dst_idev(skb->dst),
                       IPSTATS_MIB_FRAGFAILS);
         kfree_skb(skb);
         return err;
 }
 
 static inline int ip6_rt_check(struct rt6key *rt_key,
                                struct in6_addr *fl_addr,
                                struct in6_addr *addr_cache)
 {
         return ((rt_key->plen != 128 || !ipv6_addr_equal(fl_addr, &rt_key->addr)) &&
                 (addr_cache == NULL || !ipv6_addr_equal(fl_addr, addr_cache)));
 }
 
 static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
                                           struct dst_entry *dst,
                                           struct flowi *fl)
 {
         struct ipv6_pinfo *np = inet6_sk(sk);
         struct rt6_info *rt = (struct rt6_info *)dst;
 
         if (!dst)
                 goto out;
 
         /* Yes, checking route validity in not connected
          * case is not very simple. Take into account,
          * that we do not support routing by source, TOS,
          * and MSG_DONTROUTE                 --ANK (980726)
          *
          * 1. ip6_rt_check(): If route was host route,
          *    check that cached destination is current.
          *    If it is network route, we still may
          *    check its validity using saved pointer
          *    to the last used address: daddr_cache.
          *    We do not want to save whole address now,
          *    (because main consumer of this service
          *    is tcp, which has not this problem),
          *    so that the last trick works only on connected
          *    sockets.
          * 2. oif also should be the same.
          */
         if (ip6_rt_check(&rt->rt6i_dst, &fl->fl6_dst, np->daddr_cache) ||
 #ifdef CONFIG_IPV6_SUBTREES
             ip6_rt_check(&rt->rt6i_src, &fl->fl6_src, np->saddr_cache) ||
 #endif
             (fl->oif && fl->oif != dst->dev->ifindex)) {
                 dst_release(dst);
                 dst = NULL;
         }
 
 out:
         return dst;
 }
 
 static int ip6_dst_lookup_tail(struct sock *sk,
                                struct dst_entry **dst, struct flowi *fl)
 {
         int err;
         struct net *net = sock_net(sk);
 
         if (*dst == NULL)
                 *dst = ip6_route_output(net, sk, fl);
 
         if ((err = (*dst)->error))
                 goto out_err_release;
 
         if (ipv6_addr_any(&fl->fl6_src)) {
                 err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
                                          &fl->fl6_dst,
                                          sk ? inet6_sk(sk)->srcprefs : 0,
                                          &fl->fl6_src);
                 if (err)
                         goto out_err_release;
         }
 
 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
         /*
          * Here if the dst entry we've looked up
          * has a neighbour entry that is in the INCOMPLETE
          * state and the src address from the flow is
          * marked as OPTIMISTIC, we release the found
          * dst entry and replace it instead with the
          * dst entry of the nexthop router
          */
         if ((*dst)->neighbour && !((*dst)->neighbour->nud_state & NUD_VALID)) {
                 struct inet6_ifaddr *ifp;
                 struct flowi fl_gw;
                 int redirect;
 
                 ifp = ipv6_get_ifaddr(net, &fl->fl6_src,
                                       (*dst)->dev, 1);
 
                 redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
                 if (ifp)
                         in6_ifa_put(ifp);
 
                 if (redirect) {
                         /*
                          * We need to get the dst entry for the
                          * default router instead
                          */
                         dst_release(*dst);
                         memcpy(&fl_gw, fl, sizeof(struct flowi));
                         memset(&fl_gw.fl6_dst, 0, sizeof(struct in6_addr));
                         *dst = ip6_route_output(net, sk, &fl_gw);
                         if ((err = (*dst)->error))
                                 goto out_err_release;
                 }
         }
 #endif
 
         return 0;
 
 out_err_release:
         if (err == -ENETUNREACH)
                 IP6_INC_STATS_BH(net, NULL, IPSTATS_MIB_OUTNOROUTES);
         dst_release(*dst);
        *dst = NULL;
        return err;
}

/**
 *        ip6_dst_lookup - perform route lookup on flow
 *        @sk: socket which provides route info
 *        @dst: pointer to dst_entry * for result
 *        @fl: flow to lookup
 *
 *        This function performs a route lookup on the given flow.
 *
 *        It returns zero on success, or a standard errno code on error.
 */
int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
{
        *dst = NULL;
        return ip6_dst_lookup_tail(sk, dst, fl);
}
EXPORT_SYMBOL_GPL(ip6_dst_lookup);

/**
 *        ip6_sk_dst_lookup - perform socket cached route lookup on flow
 *        @sk: socket which provides the dst cache and route info
 *        @dst: pointer to dst_entry * for result
 *        @fl: flow to lookup
 *
 *        This function performs a route lookup on the given flow with the
 *        possibility of using the cached route in the socket if it is valid.
 *        It will take the socket dst lock when operating on the dst cache.
 *        As a result, this function can only be used in process context.
 *
 *        It returns zero on success, or a standard errno code on error.
 */
int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
{
        *dst = NULL;
        if (sk) {
                *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
                *dst = ip6_sk_dst_check(sk, *dst, fl);
        }

        return ip6_dst_lookup_tail(sk, dst, fl);
}
EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup);

static inline int ip6_ufo_append_data(struct sock *sk,
                        int getfrag(void *from, char *to, int offset, int len,
                        int odd, struct sk_buff *skb),
                        void *from, int length, int hh_len, int fragheaderlen,
                        int transhdrlen, int mtu,unsigned int flags)

{
        struct sk_buff *skb;
        int err;

        /* There is support for UDP large send offload by network
         * device, so create one single skb packet containing complete
         * udp datagram
         */
        if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
                skb = sock_alloc_send_skb(sk,
                        hh_len + fragheaderlen + transhdrlen + 20,
                        (flags & MSG_DONTWAIT), &err);
                if (skb == NULL)
                        return -ENOMEM;

                /* reserve space for Hardware header */
                skb_reserve(skb, hh_len);

                /* create space for UDP/IP header */
                skb_put(skb,fragheaderlen + transhdrlen);

                /* initialize network header pointer */
                skb_reset_network_header(skb);

                /* initialize protocol header pointer */
                skb->transport_header = skb->network_header + fragheaderlen;

                skb->ip_summed = CHECKSUM_PARTIAL;
                skb->csum = 0;
                sk->sk_sndmsg_off = 0;
        }

        err = skb_append_datato_frags(sk,skb, getfrag, from,
                                      (length - transhdrlen));
        if (!err) {
                struct frag_hdr fhdr;

                /* specify the length of each IP datagram fragment*/
                skb_shinfo(skb)->gso_size = mtu - fragheaderlen -
                                            sizeof(struct frag_hdr);
                skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
                ipv6_select_ident(skb, &fhdr);
                skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
                __skb_queue_tail(&sk->sk_write_queue, skb);

                return 0;
        }
        /* There is not enough support do UPD LSO,
         * so follow normal path
         */
        kfree_skb(skb);

        return err;
}

int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
        int offset, int len, int odd, struct sk_buff *skb),
        void *from, int length, int transhdrlen,
        int hlimit, int tclass, struct ipv6_txoptions *opt, struct flowi *fl,
        struct rt6_info *rt, unsigned int flags)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sk_buff *skb;
        unsigned int maxfraglen, fragheaderlen;
        int exthdrlen;
        int hh_len;
        int mtu;
        int copy;
        int err;
        int offset = 0;
        int csummode = CHECKSUM_NONE;

        if (flags&MSG_PROBE)
                return 0;
        if (skb_queue_empty(&sk->sk_write_queue)) {
                /*
                 * setup for corking
                 */
                if (opt) {
                        if (np->cork.opt == NULL) {
                                np->cork.opt = kmalloc(opt->tot_len,
                                                       sk->sk_allocation);
                                if (unlikely(np->cork.opt == NULL))
                                        return -ENOBUFS;
                        } else if (np->cork.opt->tot_len < opt->tot_len) {
                                printk(KERN_DEBUG "ip6_append_data: invalid option length\n");
                                return -EINVAL;
                        }
                        memcpy(np->cork.opt, opt, opt->tot_len);
                        inet->cork.flags |= IPCORK_OPT;
                        /* need source address above miyazawa*/
                }
                dst_hold(&rt->u.dst);
                inet->cork.dst = &rt->u.dst;
                inet->cork.fl = *fl;
                np->cork.hop_limit = hlimit;
                np->cork.tclass = tclass;
                mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
                      rt->u.dst.dev->mtu : dst_mtu(rt->u.dst.path);
                if (np->frag_size < mtu) {
                        if (np->frag_size)
                                mtu = np->frag_size;
                }
                inet->cork.fragsize = mtu;
                if (dst_allfrag(rt->u.dst.path))
                        inet->cork.flags |= IPCORK_ALLFRAG;
                inet->cork.length = 0;
                sk->sk_sndmsg_page = NULL;
                sk->sk_sndmsg_off = 0;
                exthdrlen = rt->u.dst.header_len + (opt ? opt->opt_flen : 0) -
                            rt->rt6i_nfheader_len;
                length += exthdrlen;
                transhdrlen += exthdrlen;
        } else {
                rt = (struct rt6_info *)inet->cork.dst;
                fl = &inet->cork.fl;
                if (inet->cork.flags & IPCORK_OPT)
                        opt = np->cork.opt;
                transhdrlen = 0;
                exthdrlen = 0;
                mtu = inet->cork.fragsize;
        }

        hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);

        fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
                        (opt ? opt->opt_nflen : 0);
        maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - sizeof(struct frag_hdr);

        if (mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN) {
                if (inet->cork.length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN - fragheaderlen) {
                        ipv6_local_error(sk, EMSGSIZE, fl, mtu-exthdrlen);
                        return -EMSGSIZE;
                }
        }

        /*
         * Let's try using as much space as possible.
         * Use MTU if total length of the message fits into the MTU.
         * Otherwise, we need to reserve fragment header and
         * fragment alignment (= 8-15 octects, in total).
         *
         * Note that we may need to "move" the data from the tail of
         * of the buffer to the new fragment when we split
         * the message.
         *
         * FIXME: It may be fragmented into multiple chunks
         *        at once if non-fragmentable extension headers
         *        are too large.
         * --yoshfuji
         */

        inet->cork.length += length;
        if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
            (rt->u.dst.dev->features & NETIF_F_UFO)) {

                err = ip6_ufo_append_data(sk, getfrag, from, length, hh_len,
                                          fragheaderlen, transhdrlen, mtu,
                                          flags);
                if (err)
                        goto error;
                return 0;
        }

        if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
                goto alloc_new_skb;

        while (length > 0) {
                /* Check if the remaining data fits into current packet. */
                copy = (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
                if (copy < length)
                        copy = maxfraglen - skb->len;

                if (copy <= 0) {
                        char *data;
                        unsigned int datalen;
                        unsigned int fraglen;
                        unsigned int fraggap;
                        unsigned int alloclen;
                        struct sk_buff *skb_prev;
alloc_new_skb:
                        skb_prev = skb;

                        /* There's no room in the current skb */
                        if (skb_prev)
                                fraggap = skb_prev->len - maxfraglen;
                        else
                                fraggap = 0;

                        /*
                         * If remaining data exceeds the mtu,
                         * we know we need more fragment(s).
                         */
                        datalen = length + fraggap;
                        if (datalen > (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
                                datalen = maxfraglen - fragheaderlen;

                        fraglen = datalen + fragheaderlen;
                        if ((flags & MSG_MORE) &&
                            !(rt->u.dst.dev->features&NETIF_F_SG))
                                alloclen = mtu;
                        else
                                alloclen = datalen + fragheaderlen;

                        /*
                         * The last fragment gets additional space at tail.
                         * Note: we overallocate on fragments with MSG_MODE
                         * because we have no idea if we're the last one.
                         */
                        if (datalen == length + fraggap)
                                alloclen += rt->u.dst.trailer_len;

                        /*
                         * We just reserve space for fragment header.
                         * Note: this may be overallocation if the message
                         * (without MSG_MORE) fits into the MTU.
                         */
                        alloclen += sizeof(struct frag_hdr);

                        if (transhdrlen) {
                                skb = sock_alloc_send_skb(sk,
                                                alloclen + hh_len,
                                                (flags & MSG_DONTWAIT), &err);
                        } else {
                                skb = NULL;
                                if (atomic_read(&sk->sk_wmem_alloc) <=
                                    2 * sk->sk_sndbuf)
                                        skb = sock_wmalloc(sk,
                                                           alloclen + hh_len, 1,
                                                           sk->sk_allocation);
                                if (unlikely(skb == NULL))
                                        err = -ENOBUFS;
                        }
                        if (skb == NULL)
                                goto error;
                        /*
                         *        Fill in the control structures
                         */
                        skb->ip_summed = csummode;
                        skb->csum = 0;
                        /* reserve for fragmentation */
                        skb_reserve(skb, hh_len+sizeof(struct frag_hdr));

                        /*
                         *        Find where to start putting bytes
                         */
                        data = skb_put(skb, fraglen);
                        skb_set_network_header(skb, exthdrlen);
                        data += fragheaderlen;
                        skb->transport_header = (skb->network_header +
                                                 fragheaderlen);
                        if (fraggap) {
                                skb->csum = skb_copy_and_csum_bits(
                                        skb_prev, maxfraglen,
                                        data + transhdrlen, fraggap, 0);
                                skb_prev->csum = csum_sub(skb_prev->csum,
                                                          skb->csum);
                                data += fraggap;
                                pskb_trim_unique(skb_prev, maxfraglen);
                        }
                        copy = datalen - transhdrlen - fraggap;
                        if (copy < 0) {
                                err = -EINVAL;
                                kfree_skb(skb);
                                goto error;
                        } else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
                                err = -EFAULT;
                                kfree_skb(skb);
                                goto error;
                        }

                        offset += copy;
                        length -= datalen - fraggap;
                        transhdrlen = 0;
                        exthdrlen = 0;
                        csummode = CHECKSUM_NONE;

                        /*
                         * Put the packet on the pending queue
                         */
                        __skb_queue_tail(&sk->sk_write_queue, skb);
                        continue;
                }

                if (copy > length)
                        copy = length;

                if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
                        unsigned int off;

                        off = skb->len;
                        if (getfrag(from, skb_put(skb, copy),
                                                offset, copy, off, skb) < 0) {
                                __skb_trim(skb, off);
                                err = -EFAULT;
                                goto error;
                        }
                } else {
                        int i = skb_shinfo(skb)->nr_frags;
                        skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
                        struct page *page = sk->sk_sndmsg_page;
                        int off = sk->sk_sndmsg_off;
                        unsigned int left;

                        if (page && (left = PAGE_SIZE - off) > 0) {
                                if (copy >= left)
                                        copy = left;
                                if (page != frag->page) {
                                        if (i == MAX_SKB_FRAGS) {
                                                err = -EMSGSIZE;
                                                goto error;
                                        }
                                        get_page(page);
                                        skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
                                        frag = &skb_shinfo(skb)->frags[i];
                                }
                        } else if(i < MAX_SKB_FRAGS) {
                                if (copy > PAGE_SIZE)
                                        copy = PAGE_SIZE;
                                page = alloc_pages(sk->sk_allocation, 0);
                                if (page == NULL) {
                                        err = -ENOMEM;
                                        goto error;
                                }
                                sk->sk_sndmsg_page = page;
                                sk->sk_sndmsg_off = 0;

                                skb_fill_page_desc(skb, i, page, 0, 0);
                                frag = &skb_shinfo(skb)->frags[i];
                        } else {
                                err = -EMSGSIZE;
                                goto error;
                        }
                        if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
                                err = -EFAULT;
                                goto error;
                        }
                        sk->sk_sndmsg_off += copy;
                        frag->size += copy;
                        skb->len += copy;
                        skb->data_len += copy;
                        skb->truesize += copy;
                        atomic_add(copy, &sk->sk_wmem_alloc);
                }
                offset += copy;
                length -= copy;
        }
        return 0;
error:
        inet->cork.length -= length;
        IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
        return err;
}

static void ip6_cork_release(struct inet_sock *inet, struct ipv6_pinfo *np)
{
        inet->cork.flags &= ~IPCORK_OPT;
        kfree(np->cork.opt);
        np->cork.opt = NULL;
        if (inet->cork.dst) {
                dst_release(inet->cork.dst);
                inet->cork.dst = NULL;
                inet->cork.flags &= ~IPCORK_ALLFRAG;
        }
        memset(&inet->cork.fl, 0, sizeof(inet->cork.fl));
}

int ip6_push_pending_frames(struct sock *sk)
{
        struct sk_buff *skb, *tmp_skb;
        struct sk_buff **tail_skb;
        struct in6_addr final_dst_buf, *final_dst = &final_dst_buf;
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct net *net = sock_net(sk);
        struct ipv6hdr *hdr;
        struct ipv6_txoptions *opt = np->cork.opt;
        struct rt6_info *rt = (struct rt6_info *)inet->cork.dst;
        struct flowi *fl = &inet->cork.fl;
        unsigned char proto = fl->proto;
        int err = 0;

        if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
                goto out;
        tail_skb = &(skb_shinfo(skb)->frag_list);

        /* move skb->data to ip header from ext header */
        if (skb->data < skb_network_header(skb))
                __skb_pull(skb, skb_network_offset(skb));
        while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
                __skb_pull(tmp_skb, skb_network_header_len(skb));
                *tail_skb = tmp_skb;
                tail_skb = &(tmp_skb->next);
                skb->len += tmp_skb->len;
                skb->data_len += tmp_skb->len;
                skb->truesize += tmp_skb->truesize;
                __sock_put(tmp_skb->sk);
                tmp_skb->destructor = NULL;
                tmp_skb->sk = NULL;
        }

        /* Allow local fragmentation. */
        if (np->pmtudisc < IPV6_PMTUDISC_DO)
                skb->local_df = 1;

        ipv6_addr_copy(final_dst, &fl->fl6_dst);
        __skb_pull(skb, skb_network_header_len(skb));
        if (opt && opt->opt_flen)
                ipv6_push_frag_opts(skb, opt, &proto);
        if (opt && opt->opt_nflen)
                ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst);

        skb_push(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        hdr = ipv6_hdr(skb);

        *(__be32*)hdr = fl->fl6_flowlabel |
                     htonl(0x60000000 | ((int)np->cork.tclass << 20));

        hdr->hop_limit = np->cork.hop_limit;
        hdr->nexthdr = proto;
        ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
        ipv6_addr_copy(&hdr->daddr, final_dst);

        skb->priority = sk->sk_priority;
        skb->mark = sk->sk_mark;

        skb->dst = dst_clone(&rt->u.dst);
        IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
        if (proto == IPPROTO_ICMPV6) {
                struct inet6_dev *idev = ip6_dst_idev(skb->dst);

                ICMP6MSGOUT_INC_STATS_BH(net, idev, icmp6_hdr(skb)->icmp6_type);
                ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTMSGS);
        }

        err = ip6_local_out(skb);
        if (err) {
                if (err > 0)
                        err = np->recverr ? net_xmit_errno(err) : 0;
                if (err)
                        goto error;
        }

out:
        ip6_cork_release(inet, np);
        return err;
error:
        goto out;
}

void ip6_flush_pending_frames(struct sock *sk)
{
        struct sk_buff *skb;

        while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) {
                if (skb->dst)
                        IP6_INC_STATS(sock_net(sk), ip6_dst_idev(skb->dst),
                                      IPSTATS_MIB_OUTDISCARDS);
                kfree_skb(skb);
        }

        ip6_cork_release(inet_sk(sk), inet6_sk(sk));
}