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   1 /*
   2  *      IPv6 output functions
   3  *      Linux INET6 implementation
   4  *
   5  *      Authors:
   6  *      Pedro Roque             <roque@di.fc.ul.pt>
   7  *
   8  *      $Id: ip6_output.c,v 1.34 2002/02/01 22:01:04 davem Exp $
   9  *
  10  *      Based on linux/net/ipv4/ip_output.c
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  *
  17  *      Changes:
  18  *      A.N.Kuznetsov   :       airthmetics in fragmentation.
  19  *                              extension headers are implemented.
  20  *                              route changes now work.
  21  *                              ip6_forward does not confuse sniffers.
  22  *                              etc.
  23  *
  24  *      H. von Brand    :       Added missing #include <linux/string.h>
  25  *      Imran Patel     :       frag id should be in NBO
  26  *      Kazunori MIYAZAWA @USAGI
  27  *                      :       add ip6_append_data and related functions
  28  *                              for datagram xmit
  29  */
  30
  31 #include <linux/errno.h>
  32 #include <linux/kernel.h>
  33 #include <linux/string.h>
  34 #include <linux/socket.h>
  35 #include <linux/net.h>
  36 #include <linux/netdevice.h>
  37 #include <linux/if_arp.h>
  38 #include <linux/in6.h>
  39 #include <linux/tcp.h>
  40 #include <linux/route.h>
  41 #include <linux/module.h>
  42
  43 #include <linux/netfilter.h>
  44 #include <linux/netfilter_ipv6.h>
  45
  46 #include <net/sock.h>
  47 #include <net/snmp.h>
  48
  49 #include <net/ipv6.h>
  50 #include <net/ndisc.h>
  51 #include <net/protocol.h>
  52 #include <net/ip6_route.h>
  53 #include <net/addrconf.h>
  54 #include <net/rawv6.h>
  55 #include <net/icmp.h>
  56 #include <net/xfrm.h>
  57 #include <net/checksum.h>
  58
  59 static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
  60
  61 static __inline__ void ipv6_select_ident(struct sk_buff *skb, struct frag_hdr *fhdr)
  62 {
  63         static u32 ipv6_fragmentation_id = 1;
  64         static DEFINE_SPINLOCK(ip6_id_lock);
  65
  66         spin_lock_bh(&ip6_id_lock);
  67         fhdr->identification = htonl(ipv6_fragmentation_id);
  68         if (++ipv6_fragmentation_id == 0)
  69                 ipv6_fragmentation_id = 1;
  70         spin_unlock_bh(&ip6_id_lock);
  71 }
  72
  73 int __ip6_local_out(struct sk_buff *skb)
  74 {
  75         int len;
  76
  77         len = skb->len - sizeof(struct ipv6hdr);
  78         if (len > IPV6_MAXPLEN)
  79                 len = 0;
  80         ipv6_hdr(skb)->payload_len = htons(len);
  81
  82         return nf_hook(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, skb->dst->dev,
  83                        dst_output);
  84 }
  85
  86 int ip6_local_out(struct sk_buff *skb)
  87 {
  88         int err;
  89
  90         err = __ip6_local_out(skb);
  91         if (likely(err == 1))
  92                 err = dst_output(skb);
  93
  94         return err;
  95 }
  96 EXPORT_SYMBOL_GPL(ip6_local_out);
  97
  98 static int ip6_output_finish(struct sk_buff *skb)
  99 {
 100         struct dst_entry *dst = skb->dst;
 101
 102         if (dst->hh)
 103                 return neigh_hh_output(dst->hh, skb);
 104         else if (dst->neighbour)
 105                 return dst->neighbour->output(skb);
 106
 107         IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
 108         kfree_skb(skb);
 109         return -EINVAL;
 110
 111 }
 112
 113 /* dev_loopback_xmit for use with netfilter. */
 114 static int ip6_dev_loopback_xmit(struct sk_buff *newskb)
 115 {
 116         skb_reset_mac_header(newskb);
 117         __skb_pull(newskb, skb_network_offset(newskb));
 118         newskb->pkt_type = PACKET_LOOPBACK;
 119         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 120         BUG_TRAP(newskb->dst);
 121
 122         netif_rx(newskb);
 123         return 0;
 124 }
 125
 126
 127 static int ip6_output2(struct sk_buff *skb)
 128 {
 129         struct dst_entry *dst = skb->dst;
 130         struct net_device *dev = dst->dev;
 131
 132         skb->protocol = htons(ETH_P_IPV6);
 133         skb->dev = dev;
 134
 135         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
 136                 struct ipv6_pinfo* np = skb->sk ? inet6_sk(skb->sk) : NULL;
 137                 struct inet6_dev *idev = ip6_dst_idev(skb->dst);
 138
 139                 if (!(dev->flags & IFF_LOOPBACK) && (!np || np->mc_loop) &&
 140                     ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
 141                                         &ipv6_hdr(skb)->saddr)) {
 142                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 143
 144                         /* Do not check for IFF_ALLMULTI; multicast routing
 145                            is not supported in any case.
 146                          */
 147                         if (newskb)
 148                                 NF_HOOK(PF_INET6, NF_INET_POST_ROUTING, newskb,
 149                                         NULL, newskb->dev,
 150                                         ip6_dev_loopback_xmit);
 151
 152                         if (ipv6_hdr(skb)->hop_limit == 0) {
 153                                 IP6_INC_STATS(idev, IPSTATS_MIB_OUTDISCARDS);
 154                                 kfree_skb(skb);
 155                                 return 0;
 156                         }
 157                 }
 158
 159                 IP6_INC_STATS(idev, IPSTATS_MIB_OUTMCASTPKTS);
 160         }
 161
 162         return NF_HOOK(PF_INET6, NF_INET_POST_ROUTING, skb, NULL, skb->dev,
 163                        ip6_output_finish);
 164 }
 165
 166 static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
 167 {
 168         struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
 169
 170         return (np && np->pmtudisc == IPV6_PMTUDISC_PROBE) ?
 171                skb->dst->dev->mtu : dst_mtu(skb->dst);
 172 }
 173
 174 int ip6_output(struct sk_buff *skb)
 175 {
 176         if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
 177                                 dst_allfrag(skb->dst))
 178                 return ip6_fragment(skb, ip6_output2);
 179         else
 180                 return ip6_output2(skb);
 181 }
 182
 183 /*
 184  *      xmit an sk_buff (used by TCP)
 185  */
 186
 187 int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
 188              struct ipv6_txoptions *opt, int ipfragok)
 189 {
 190         struct ipv6_pinfo *np = inet6_sk(sk);
 191         struct in6_addr *first_hop = &fl->fl6_dst;
 192         struct dst_entry *dst = skb->dst;
 193         struct ipv6hdr *hdr;
 194         u8  proto = fl->proto;
 195         int seg_len = skb->len;
 196         int hlimit, tclass;
 197         u32 mtu;
 198
 199         if (opt) {
 200                 unsigned int head_room;
 201
 202                 /* First: exthdrs may take lots of space (~8K for now)
 203                    MAX_HEADER is not enough.
 204                  */
 205                 head_room = opt->opt_nflen + opt->opt_flen;
 206                 seg_len += head_room;
 207                 head_room += sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
 208
 209                 if (skb_headroom(skb) < head_room) {
 210                         struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
 211                         if (skb2 == NULL) {
 212                                 IP6_INC_STATS(ip6_dst_idev(skb->dst),
 213                                               IPSTATS_MIB_OUTDISCARDS);
 214                                 kfree_skb(skb);
 215                                 return -ENOBUFS;
 216                         }
 217                         kfree_skb(skb);
 218                         skb = skb2;
 219                         if (sk)
 220                                 skb_set_owner_w(skb, sk);
 221                 }
 222                 if (opt->opt_flen)
 223                         ipv6_push_frag_opts(skb, opt, &proto);
 224                 if (opt->opt_nflen)
 225                         ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop);
 226         }
 227
 228         skb_push(skb, sizeof(struct ipv6hdr));
 229         skb_reset_network_header(skb);
 230         hdr = ipv6_hdr(skb);
 231
 232         /*
 233          *      Fill in the IPv6 header
 234          */
 235
 236         hlimit = -1;
 237         if (np)
 238                 hlimit = np->hop_limit;
 239         if (hlimit < 0)
 240                 hlimit = dst_metric(dst, RTAX_HOPLIMIT);
 241         if (hlimit < 0)
 242                 hlimit = ipv6_get_hoplimit(dst->dev);
 243
 244         tclass = -1;
 245         if (np)
 246                 tclass = np->tclass;
 247         if (tclass < 0)
 248                 tclass = 0;
 249
 250         *(__be32 *)hdr = htonl(0x60000000 | (tclass << 20)) | fl->fl6_flowlabel;
 251
 252         hdr->payload_len = htons(seg_len);
 253         hdr->nexthdr = proto;
 254         hdr->hop_limit = hlimit;
 255
 256         ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
 257         ipv6_addr_copy(&hdr->daddr, first_hop);
 258
 259         skb->priority = sk->sk_priority;
 260         skb->mark = sk->sk_mark;
 261
 262         mtu = dst_mtu(dst);
 263         if ((skb->len <= mtu) || ipfragok || skb_is_gso(skb)) {
 264                 IP6_INC_STATS(ip6_dst_idev(skb->dst),
 265                               IPSTATS_MIB_OUTREQUESTS);
 266                 return NF_HOOK(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, dst->dev,
 267                                 dst_output);
 268         }
 269
 270         if (net_ratelimit())
 271                 printk(KERN_DEBUG "IPv6: sending pkt_too_big to self\n");
 272         skb->dev = dst->dev;
 273         icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
 274         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
 275         kfree_skb(skb);
 276         return -EMSGSIZE;
 277 }
 278
 279 EXPORT_SYMBOL(ip6_xmit);
 280
 281 /*
 282  *      To avoid extra problems ND packets are send through this
 283  *      routine. It's code duplication but I really want to avoid
 284  *      extra checks since ipv6_build_header is used by TCP (which
 285  *      is for us performance critical)
 286  */
 287
 288 int ip6_nd_hdr(struct sock *sk, struct sk_buff *skb, struct net_device *dev,
 289                struct in6_addr *saddr, struct in6_addr *daddr,
 290                int proto, int len)
 291 {
 292         struct ipv6_pinfo *np = inet6_sk(sk);
 293         struct ipv6hdr *hdr;
 294         int totlen;
 295
 296         skb->protocol = htons(ETH_P_IPV6);
 297         skb->dev = dev;
 298
 299         totlen = len + sizeof(struct ipv6hdr);
 300
 301         skb_reset_network_header(skb);
 302         skb_put(skb, sizeof(struct ipv6hdr));
 303         hdr = ipv6_hdr(skb);
 304
 305         *(__be32*)hdr = htonl(0x60000000);
 306
 307         hdr->payload_len = htons(len);
 308         hdr->nexthdr = proto;
 309         hdr->hop_limit = np->hop_limit;
 310
 311         ipv6_addr_copy(&hdr->saddr, saddr);
 312         ipv6_addr_copy(&hdr->daddr, daddr);
 313
 314         return 0;
 315 }
 316
 317 static int ip6_call_ra_chain(struct sk_buff *skb, int sel)
 318 {
 319         struct ip6_ra_chain *ra;
 320         struct sock *last = NULL;
 321
 322         read_lock(&ip6_ra_lock);
 323         for (ra = ip6_ra_chain; ra; ra = ra->next) {
 324                 struct sock *sk = ra->sk;
 325                 if (sk && ra->sel == sel &&
 326                     (!sk->sk_bound_dev_if ||
 327                      sk->sk_bound_dev_if == skb->dev->ifindex)) {
 328                         if (last) {
 329                                 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
 330                                 if (skb2)
 331                                         rawv6_rcv(last, skb2);
 332                         }
 333                         last = sk;
 334                 }
 335         }
 336
 337         if (last) {
 338                 rawv6_rcv(last, skb);
 339                 read_unlock(&ip6_ra_lock);
 340                 return 1;
 341         }
 342         read_unlock(&ip6_ra_lock);
 343         return 0;
 344 }
 345
 346 static int ip6_forward_proxy_check(struct sk_buff *skb)
 347 {
 348         struct ipv6hdr *hdr = ipv6_hdr(skb);
 349         u8 nexthdr = hdr->nexthdr;
 350         int offset;
 351
 352         if (ipv6_ext_hdr(nexthdr)) {
 353                 offset = ipv6_skip_exthdr(skb, sizeof(*hdr), &nexthdr);
 354                 if (offset < 0)
 355                         return 0;
 356         } else
 357                 offset = sizeof(struct ipv6hdr);
 358
 359         if (nexthdr == IPPROTO_ICMPV6) {
 360                 struct icmp6hdr *icmp6;
 361
 362                 if (!pskb_may_pull(skb, (skb_network_header(skb) +
 363                                          offset + 1 - skb->data)))
 364                         return 0;
 365
 366                 icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
 367
 368                 switch (icmp6->icmp6_type) {
 369                 case NDISC_ROUTER_SOLICITATION:
 370                 case NDISC_ROUTER_ADVERTISEMENT:
 371                 case NDISC_NEIGHBOUR_SOLICITATION:
 372                 case NDISC_NEIGHBOUR_ADVERTISEMENT:
 373                 case NDISC_REDIRECT:
 374                         /* For reaction involving unicast neighbor discovery
 375                          * message destined to the proxied address, pass it to
 376                          * input function.
 377                          */
 378                         return 1;
 379                 default:
 380                         break;
 381                 }
 382         }
 383
 384         /*
 385          * The proxying router can't forward traffic sent to a link-local
 386          * address, so signal the sender and discard the packet. This
 387          * behavior is clarified by the MIPv6 specification.
 388          */
 389         if (ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) {
 390                 dst_link_failure(skb);
 391                 return -1;
 392         }
 393
 394         return 0;
 395 }
 396
 397 static inline int ip6_forward_finish(struct sk_buff *skb)
 398 {
 399         return dst_output(skb);
 400 }
 401
 402 int ip6_forward(struct sk_buff *skb)
 403 {
 404         struct dst_entry *dst = skb->dst;
 405         struct ipv6hdr *hdr = ipv6_hdr(skb);
 406         struct inet6_skb_parm *opt = IP6CB(skb);
 407
 408         if (ipv6_devconf.forwarding == 0)
 409                 goto error;
 410
 411         if (!xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 412                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
 413                 goto drop;
 414         }
 415
 416         skb_forward_csum(skb);
 417
 418         /*
 419          *      We DO NOT make any processing on
 420          *      RA packets, pushing them to user level AS IS
 421          *      without ane WARRANTY that application will be able
 422          *      to interpret them. The reason is that we
 423          *      cannot make anything clever here.
 424          *
 425          *      We are not end-node, so that if packet contains
 426          *      AH/ESP, we cannot make anything.
 427          *      Defragmentation also would be mistake, RA packets
 428          *      cannot be fragmented, because there is no warranty
 429          *      that different fragments will go along one path. --ANK
 430          */
 431         if (opt->ra) {
 432                 u8 *ptr = skb_network_header(skb) + opt->ra;
 433                 if (ip6_call_ra_chain(skb, (ptr[2]<<8) + ptr[3]))
 434                         return 0;
 435         }
 436
 437         /*
 438          *      check and decrement ttl
 439          */
 440         if (hdr->hop_limit <= 1) {
 441                 /* Force OUTPUT device used as source address */
 442                 skb->dev = dst->dev;
 443                 icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
 444                             0, skb->dev);
 445                 IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
 446
 447                 kfree_skb(skb);
 448                 return -ETIMEDOUT;
 449         }
 450
 451         /* XXX: idev->cnf.proxy_ndp? */
 452         if (ipv6_devconf.proxy_ndp &&
 453             pneigh_lookup(&nd_tbl, &init_net, &hdr->daddr, skb->dev, 0)) {
 454                 int proxied = ip6_forward_proxy_check(skb);
 455                 if (proxied > 0)
 456                         return ip6_input(skb);
 457                 else if (proxied < 0) {
 458                         IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
 459                         goto drop;
 460                 }
 461         }
 462
 463         if (!xfrm6_route_forward(skb)) {
 464                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_INDISCARDS);
 465                 goto drop;
 466         }
 467         dst = skb->dst;
 468
 469         /* IPv6 specs say nothing about it, but it is clear that we cannot
 470            send redirects to source routed frames.
 471            We don't send redirects to frames decapsulated from IPsec.
 472          */
 473         if (skb->dev == dst->dev && dst->neighbour && opt->srcrt == 0 &&
 474             !skb->sp) {
 475                 struct in6_addr *target = NULL;
 476                 struct rt6_info *rt;
 477                 struct neighbour *n = dst->neighbour;
 478
 479                 /*
 480                  *      incoming and outgoing devices are the same
 481                  *      send a redirect.
 482                  */
 483
 484                 rt = (struct rt6_info *) dst;
 485                 if ((rt->rt6i_flags & RTF_GATEWAY))
 486                         target = (struct in6_addr*)&n->primary_key;
 487                 else
 488                         target = &hdr->daddr;
 489
 490                 /* Limit redirects both by destination (here)
 491                    and by source (inside ndisc_send_redirect)
 492                  */
 493                 if (xrlim_allow(dst, 1*HZ))
 494                         ndisc_send_redirect(skb, n, target);
 495         } else {
 496                 int addrtype = ipv6_addr_type(&hdr->saddr);
 497
 498                 /* This check is security critical. */
 499                 if (addrtype & (IPV6_ADDR_MULTICAST|IPV6_ADDR_LOOPBACK))
 500                         goto error;
 501                 if (addrtype & IPV6_ADDR_LINKLOCAL) {
 502                         icmpv6_send(skb, ICMPV6_DEST_UNREACH,
 503                                 ICMPV6_NOT_NEIGHBOUR, 0, skb->dev);
 504                         goto error;
 505                 }
 506         }
 507
 508         if (skb->len > dst_mtu(dst)) {
 509                 /* Again, force OUTPUT device used as source address */
 510                 skb->dev = dst->dev;
 511                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, dst_mtu(dst), skb->dev);
 512                 IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INTOOBIGERRORS);
 513                 IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_FRAGFAILS);
 514                 kfree_skb(skb);
 515                 return -EMSGSIZE;
 516         }
 517
 518         if (skb_cow(skb, dst->dev->hard_header_len)) {
 519                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
 520                 goto drop;
 521         }
 522
 523         hdr = ipv6_hdr(skb);
 524
 525         /* Mangling hops number delayed to point after skb COW */
 526
 527         hdr->hop_limit--;
 528
 529         IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
 530         return NF_HOOK(PF_INET6, NF_INET_FORWARD, skb, skb->dev, dst->dev,
 531                        ip6_forward_finish);
 532
 533 error:
 534         IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_INADDRERRORS);
 535 drop:
 536         kfree_skb(skb);
 537         return -EINVAL;
 538 }
 539
 540 static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 541 {
 542         to->pkt_type = from->pkt_type;
 543         to->priority = from->priority;
 544         to->protocol = from->protocol;
 545         dst_release(to->dst);
 546         to->dst = dst_clone(from->dst);
 547         to->dev = from->dev;
 548         to->mark = from->mark;
 549
 550 #ifdef CONFIG_NET_SCHED
 551         to->tc_index = from->tc_index;
 552 #endif
 553         nf_copy(to, from);
 554 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
 555     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 556         to->nf_trace = from->nf_trace;
 557 #endif
 558         skb_copy_secmark(to, from);
 559 }
 560
 561 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 562 {
 563         u16 offset = sizeof(struct ipv6hdr);
 564         struct ipv6_opt_hdr *exthdr =
 565                                 (struct ipv6_opt_hdr *)(ipv6_hdr(skb) + 1);
 566         unsigned int packet_len = skb->tail - skb->network_header;
 567         int found_rhdr = 0;
 568         *nexthdr = &ipv6_hdr(skb)->nexthdr;
 569
 570         while (offset + 1 <= packet_len) {
 571
 572                 switch (**nexthdr) {
 573
 574                 case NEXTHDR_HOP:
 575                         break;
 576                 case NEXTHDR_ROUTING:
 577                         found_rhdr = 1;
 578                         break;
 579                 case NEXTHDR_DEST:
 580 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 581                         if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0)
 582                                 break;
 583 #endif
 584                         if (found_rhdr)
 585                                 return offset;
 586                         break;
 587                 default :
 588                         return offset;
 589                 }
 590
 591                 offset += ipv6_optlen(exthdr);
 592                 *nexthdr = &exthdr->nexthdr;
 593                 exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
 594                                                  offset);
 595         }
 596
 597         return offset;
 598 }
 599 EXPORT_SYMBOL_GPL(ip6_find_1stfragopt);
 600
 601 static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 602 {
 603         struct net_device *dev;
 604         struct sk_buff *frag;
 605         struct rt6_info *rt = (struct rt6_info*)skb->dst;
 606         struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL;
 607         struct ipv6hdr *tmp_hdr;
 608         struct frag_hdr *fh;
 609         unsigned int mtu, hlen, left, len;
 610         __be32 frag_id = 0;
 611         int ptr, offset = 0, err=0;
 612         u8 *prevhdr, nexthdr = 0;
 613
 614         dev = rt->u.dst.dev;
 615         hlen = ip6_find_1stfragopt(skb, &prevhdr);
 616         nexthdr = *prevhdr;
 617
 618         mtu = ip6_skb_dst_mtu(skb);
 619
 620         /* We must not fragment if the socket is set to force MTU discovery
 621          * or if the skb it not generated by a local socket.  (This last
 622          * check should be redundant, but it's free.)
 623          */
 624         if (!np || np->pmtudisc >= IPV6_PMTUDISC_DO) {
 625                 skb->dev = skb->dst->dev;
 626                 icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
 627                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
 628                 kfree_skb(skb);
 629                 return -EMSGSIZE;
 630         }
 631
 632         if (np && np->frag_size < mtu) {
 633                 if (np->frag_size)
 634                         mtu = np->frag_size;
 635         }
 636         mtu -= hlen + sizeof(struct frag_hdr);
 637
 638         if (skb_shinfo(skb)->frag_list) {
 639                 int first_len = skb_pagelen(skb);
 640                 int truesizes = 0;
 641
 642                 if (first_len - hlen > mtu ||
 643                     ((first_len - hlen) & 7) ||
 644                     skb_cloned(skb))
 645                         goto slow_path;
 646
 647                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
 648                         /* Correct geometry. */
 649                         if (frag->len > mtu ||
 650                             ((frag->len & 7) && frag->next) ||
 651                             skb_headroom(frag) < hlen)
 652                             goto slow_path;
 653
 654                         /* Partially cloned skb? */
 655                         if (skb_shared(frag))
 656                                 goto slow_path;
 657
 658                         BUG_ON(frag->sk);
 659                         if (skb->sk) {
 660                                 sock_hold(skb->sk);
 661                                 frag->sk = skb->sk;
 662                                 frag->destructor = sock_wfree;
 663                                 truesizes += frag->truesize;
 664                         }
 665                 }
 666
 667                 err = 0;
 668                 offset = 0;
 669                 frag = skb_shinfo(skb)->frag_list;
 670                 skb_shinfo(skb)->frag_list = NULL;
 671                 /* BUILD HEADER */
 672
 673                 *prevhdr = NEXTHDR_FRAGMENT;
 674                 tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
 675                 if (!tmp_hdr) {
 676                         IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGFAILS);
 677                         return -ENOMEM;
 678                 }
 679
 680                 __skb_pull(skb, hlen);
 681                 fh = (struct frag_hdr*)__skb_push(skb, sizeof(struct frag_hdr));
 682                 __skb_push(skb, hlen);
 683                 skb_reset_network_header(skb);
 684                 memcpy(skb_network_header(skb), tmp_hdr, hlen);
 685
 686                 ipv6_select_ident(skb, fh);
 687                 fh->nexthdr = nexthdr;
 688                 fh->reserved = 0;
 689                 fh->frag_off = htons(IP6_MF);
 690                 frag_id = fh->identification;
 691
 692                 first_len = skb_pagelen(skb);
 693                 skb->data_len = first_len - skb_headlen(skb);
 694                 skb->truesize -= truesizes;
 695                 skb->len = first_len;
 696                 ipv6_hdr(skb)->payload_len = htons(first_len -
 697                                                    sizeof(struct ipv6hdr));
 698
 699                 dst_hold(&rt->u.dst);
 700
 701                 for (;;) {
 702                         /* Prepare header of the next frame,
 703                          * before previous one went down. */
 704                         if (frag) {
 705                                 frag->ip_summed = CHECKSUM_NONE;
 706                                 skb_reset_transport_header(frag);
 707                                 fh = (struct frag_hdr*)__skb_push(frag, sizeof(struct frag_hdr));
 708                                 __skb_push(frag, hlen);
 709                                 skb_reset_network_header(frag);
 710                                 memcpy(skb_network_header(frag), tmp_hdr,
 711                                        hlen);
 712                                 offset += skb->len - hlen - sizeof(struct frag_hdr);
 713                                 fh->nexthdr = nexthdr;
 714                                 fh->reserved = 0;
 715                                 fh->frag_off = htons(offset);
 716                                 if (frag->next != NULL)
 717                                         fh->frag_off |= htons(IP6_MF);
 718                                 fh->identification = frag_id;
 719                                 ipv6_hdr(frag)->payload_len =
 720                                                 htons(frag->len -
 721                                                       sizeof(struct ipv6hdr));
 722                                 ip6_copy_metadata(frag, skb);
 723                         }
 724
 725                         err = output(skb);
 726                         if(!err)
 727                                 IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGCREATES);
 728
 729                         if (err || !frag)
 730                                 break;
 731
 732                         skb = frag;
 733                         frag = skb->next;
 734                         skb->next = NULL;
 735                 }
 736
 737                 kfree(tmp_hdr);
 738
 739                 if (err == 0) {
 740                         IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGOKS);
 741                         dst_release(&rt->u.dst);
 742                         return 0;
 743                 }
 744
 745                 while (frag) {
 746                         skb = frag->next;
 747                         kfree_skb(frag);
 748                         frag = skb;
 749                 }
 750
 751                 IP6_INC_STATS(ip6_dst_idev(&rt->u.dst), IPSTATS_MIB_FRAGFAILS);
 752                 dst_release(&rt->u.dst);
 753                 return err;
 754         }
 755
 756 slow_path:
 757         left = skb->len - hlen;         /* Space per frame */
 758         ptr = hlen;                     /* Where to start from */
 759
 760         /*
 761          *      Fragment the datagram.
 762          */
 763
 764         *prevhdr = NEXTHDR_FRAGMENT;
 765
 766         /*
 767          *      Keep copying data until we run out.
 768          */
 769         while(left > 0) {
 770                 len = left;
 771                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 772                 if (len > mtu)
 773                         len = mtu;
 774                 /* IF: we are not sending upto and including the packet end
 775                    then align the next start on an eight byte boundary */
 776                 if (len < left) {
 777                         len &= ~7;
 778                 }
 779                 /*
 780                  *      Allocate buffer.
 781                  */
 782
 783                 if ((frag = alloc_skb(len+hlen+sizeof(struct frag_hdr)+LL_RESERVED_SPACE(rt->u.dst.dev), GFP_ATOMIC)) == NULL) {
 784                         NETDEBUG(KERN_INFO "IPv6: frag: no memory for new fragment!\n");
 785                         IP6_INC_STATS(ip6_dst_idev(skb->dst),
 786                                       IPSTATS_MIB_FRAGFAILS);
 787                         err = -ENOMEM;
 788                         goto fail;
 789                 }
 790
 791                 /*
 792                  *      Set up data on packet
 793                  */
 794
 795                 ip6_copy_metadata(frag, skb);
 796                 skb_reserve(frag, LL_RESERVED_SPACE(rt->u.dst.dev));
 797                 skb_put(frag, len + hlen + sizeof(struct frag_hdr));
 798                 skb_reset_network_header(frag);
 799                 fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
 800                 frag->transport_header = (frag->network_header + hlen +
 801                                           sizeof(struct frag_hdr));
 802
 803                 /*
 804                  *      Charge the memory for the fragment to any owner
 805                  *      it might possess
 806                  */
 807                 if (skb->sk)
 808                         skb_set_owner_w(frag, skb->sk);
 809
 810                 /*
 811                  *      Copy the packet header into the new buffer.
 812                  */
 813                 skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);
 814
 815                 /*
 816                  *      Build fragment header.
 817                  */
 818                 fh->nexthdr = nexthdr;
 819                 fh->reserved = 0;
 820                 if (!frag_id) {
 821                         ipv6_select_ident(skb, fh);
 822                         frag_id = fh->identification;
 823                 } else
 824                         fh->identification = frag_id;
 825
 826                 /*
 827                  *      Copy a block of the IP datagram.
 828                  */
 829                 if (skb_copy_bits(skb, ptr, skb_transport_header(frag), len))
 830                         BUG();
 831                 left -= len;
 832
 833                 fh->frag_off = htons(offset);
 834                 if (left > 0)
 835                         fh->frag_off |= htons(IP6_MF);
 836                 ipv6_hdr(frag)->payload_len = htons(frag->len -
 837                                                     sizeof(struct ipv6hdr));
 838
 839                 ptr += len;
 840                 offset += len;
 841
 842                 /*
 843                  *      Put this fragment into the sending queue.
 844                  */
 845                 err = output(frag);
 846                 if (err)
 847                         goto fail;
 848
 849                 IP6_INC_STATS(ip6_dst_idev(skb->dst), IPSTATS_MIB_FRAGCREATES);
 850         }
 851         IP6_INC_STATS(ip6_dst_idev(skb->dst),
 852                       IPSTATS_MIB_FRAGOKS);
 853         kfree_skb(skb);
 854         return err;
 855
 856 fail:
 857         IP6_INC_STATS(ip6_dst_idev(skb->dst),
 858                       IPSTATS_MIB_FRAGFAILS);
 859         kfree_skb(skb);
 860         return err;
 861 }
 862
 863 static inline int ip6_rt_check(struct rt6key *rt_key,
 864                                struct in6_addr *fl_addr,
 865                                struct in6_addr *addr_cache)
 866 {
 867         return ((rt_key->plen != 128 || !ipv6_addr_equal(fl_addr, &rt_key->addr)) &&
 868                 (addr_cache == NULL || !ipv6_addr_equal(fl_addr, addr_cache)));
 869 }
 870
 871 static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
 872                                           struct dst_entry *dst,
 873                                           struct flowi *fl)
 874 {
 875         struct ipv6_pinfo *np = inet6_sk(sk);
 876         struct rt6_info *rt = (struct rt6_info *)dst;
 877
 878         if (!dst)
 879                 goto out;
 880
 881         /* Yes, checking route validity in not connected
 882          * case is not very simple. Take into account,
 883          * that we do not support routing by source, TOS,
 884          * and MSG_DONTROUTE            --ANK (980726)
 885          *
 886          * 1. ip6_rt_check(): If route was host route,
 887          *    check that cached destination is current.
 888          *    If it is network route, we still may
 889          *    check its validity using saved pointer
 890          *    to the last used address: daddr_cache.
 891          *    We do not want to save whole address now,
 892          *    (because main consumer of this service
 893          *    is tcp, which has not this problem),
 894          *    so that the last trick works only on connected
 895          *    sockets.
 896          * 2. oif also should be the same.
 897          */
 898         if (ip6_rt_check(&rt->rt6i_dst, &fl->fl6_dst, np->daddr_cache) ||
 899 #ifdef CONFIG_IPV6_SUBTREES
 900             ip6_rt_check(&rt->rt6i_src, &fl->fl6_src, np->saddr_cache) ||
 901 #endif
 902             (fl->oif && fl->oif != dst->dev->ifindex)) {
 903                 dst_release(dst);
 904                 dst = NULL;
 905         }
 906
 907 out:
 908         return dst;
 909 }
 910
 911 static int ip6_dst_lookup_tail(struct sock *sk,
 912                                struct dst_entry **dst, struct flowi *fl)
 913 {
 914         int err;
 915
 916         if (*dst == NULL)
 917                 *dst = ip6_route_output(sk, fl);
 918
 919         if ((err = (*dst)->error))
 920                 goto out_err_release;
 921
 922         if (ipv6_addr_any(&fl->fl6_src)) {
 923                 err = ipv6_get_saddr(*dst, &fl->fl6_dst, &fl->fl6_src);
 924                 if (err)
 925                         goto out_err_release;
 926         }
 927
 928 #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
 929                 /*
 930                  * Here if the dst entry we've looked up
 931                  * has a neighbour entry that is in the INCOMPLETE
 932                  * state and the src address from the flow is
 933                  * marked as OPTIMISTIC, we release the found
 934                  * dst entry and replace it instead with the
 935                  * dst entry of the nexthop router
 936                  */
 937                 if (!((*dst)->neighbour->nud_state & NUD_VALID)) {
 938                         struct inet6_ifaddr *ifp;
 939                         struct flowi fl_gw;
 940                         int redirect;
 941
 942                         ifp = ipv6_get_ifaddr(&init_net, &fl->fl6_src,
 943                                               (*dst)->dev, 1);
 944
 945                         redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
 946                         if (ifp)
 947                                 in6_ifa_put(ifp);
 948
 949                         if (redirect) {
 950                                 /*
 951                                  * We need to get the dst entry for the
 952                                  * default router instead
 953                                  */
 954                                 dst_release(*dst);
 955                                 memcpy(&fl_gw, fl, sizeof(struct flowi));
 956                                 memset(&fl_gw.fl6_dst, 0, sizeof(struct in6_addr));
 957                                 *dst = ip6_route_output(sk, &fl_gw);
 958                                 if ((err = (*dst)->error))
 959                                         goto out_err_release;
 960                         }
 961                 }
 962 #endif
 963
 964         return 0;
 965
 966 out_err_release:
 967         if (err == -ENETUNREACH)
 968                 IP6_INC_STATS_BH(NULL, IPSTATS_MIB_OUTNOROUTES);
 969         dst_release(*dst);
 970         *dst = NULL;
 971         return err;
 972 }
 973
 974 /**
 975  *      ip6_dst_lookup - perform route lookup on flow
 976  *      @sk: socket which provides route info
 977  *      @dst: pointer to dst_entry * for result
 978  *      @fl: flow to lookup
 979  *
 980  *      This function performs a route lookup on the given flow.
 981  *
 982  *      It returns zero on success, or a standard errno code on error.
 983  */
 984 int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
 985 {
 986         *dst = NULL;
 987         return ip6_dst_lookup_tail(sk, dst, fl);
 988 }
 989 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
 990
 991 /**
 992  *      ip6_sk_dst_lookup - perform socket cached route lookup on flow
 993  *      @sk: socket which provides the dst cache and route info
 994  *      @dst: pointer to dst_entry * for result
 995  *      @fl: flow to lookup
 996  *
 997  *      This function performs a route lookup on the given flow with the
 998  *      possibility of using the cached route in the socket if it is valid.
 999  *      It will take the socket dst lock when operating on the dst cache.
1000  *      As a result, this function can only be used in process context.
1001  *
1002  *      It returns zero on success, or a standard errno code on error.
1003  */
1004 int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
1005 {
1006         *dst = NULL;
1007         if (sk) {
1008                 *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
1009                 *dst = ip6_sk_dst_check(sk, *dst, fl);
1010         }
1011
1012         return ip6_dst_lookup_tail(sk, dst, fl);
1013 }
1014 EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup);
1015
1016 static inline int ip6_ufo_append_data(struct sock *sk,
1017                         int getfrag(void *from, char *to, int offset, int len,
1018                         int odd, struct sk_buff *skb),
1019                         void *from, int length, int hh_len, int fragheaderlen,
1020                         int transhdrlen, int mtu,unsigned int flags)
1021
1022 {
1023         struct sk_buff *skb;
1024         int err;
1025
1026         /* There is support for UDP large send offload by network
1027          * device, so create one single skb packet containing complete
1028          * udp datagram
1029          */
1030         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
1031                 skb = sock_alloc_send_skb(sk,
1032                         hh_len + fragheaderlen + transhdrlen + 20,
1033                         (flags & MSG_DONTWAIT), &err);
1034                 if (skb == NULL)
1035                         return -ENOMEM;
1036
1037                 /* reserve space for Hardware header */
1038                 skb_reserve(skb, hh_len);
1039
1040                 /* create space for UDP/IP header */
1041                 skb_put(skb,fragheaderlen + transhdrlen);
1042
1043                 /* initialize network header pointer */
1044                 skb_reset_network_header(skb);
1045
1046                 /* initialize protocol header pointer */
1047                 skb->transport_header = skb->network_header + fragheaderlen;
1048
1049                 skb->ip_summed = CHECKSUM_PARTIAL;
1050                 skb->csum = 0;
1051                 sk->sk_sndmsg_off = 0;
1052         }
1053
1054         err = skb_append_datato_frags(sk,skb, getfrag, from,
1055                                       (length - transhdrlen));
1056         if (!err) {
1057                 struct frag_hdr fhdr;
1058
1059                 /* specify the length of each IP datagram fragment*/
1060                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen -
1061                                             sizeof(struct frag_hdr);
1062                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1063                 ipv6_select_ident(skb, &fhdr);
1064                 skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
1065                 __skb_queue_tail(&sk->sk_write_queue, skb);
1066
1067                 return 0;
1068         }
1069         /* There is not enough support do UPD LSO,
1070          * so follow normal path
1071          */
1072         kfree_skb(skb);
1073
1074         return err;
1075 }
1076
1077 int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
1078         int offset, int len, int odd, struct sk_buff *skb),
1079         void *from, int length, int transhdrlen,
1080         int hlimit, int tclass, struct ipv6_txoptions *opt, struct flowi *fl,
1081         struct rt6_info *rt, unsigned int flags)
1082 {
1083         struct inet_sock *inet = inet_sk(sk);
1084         struct ipv6_pinfo *np = inet6_sk(sk);
1085         struct sk_buff *skb;
1086         unsigned int maxfraglen, fragheaderlen;
1087         int exthdrlen;
1088         int hh_len;
1089         int mtu;
1090         int copy;
1091         int err;
1092         int offset = 0;
1093         int csummode = CHECKSUM_NONE;
1094
1095         if (flags&MSG_PROBE)
1096                 return 0;
1097         if (skb_queue_empty(&sk->sk_write_queue)) {
1098                 /*
1099                  * setup for corking
1100                  */
1101                 if (opt) {
1102                         if (np->cork.opt == NULL) {
1103                                 np->cork.opt = kmalloc(opt->tot_len,
1104                                                        sk->sk_allocation);
1105                                 if (unlikely(np->cork.opt == NULL))
1106                                         return -ENOBUFS;
1107                         } else if (np->cork.opt->tot_len < opt->tot_len) {
1108                                 printk(KERN_DEBUG "ip6_append_data: invalid option length\n");
1109                                 return -EINVAL;
1110                         }
1111                         memcpy(np->cork.opt, opt, opt->tot_len);
1112                         inet->cork.flags |= IPCORK_OPT;
1113                         /* need source address above miyazawa*/
1114                 }
1115                 dst_hold(&rt->u.dst);
1116                 np->cork.rt = rt;
1117                 inet->cork.fl = *fl;
1118                 np->cork.hop_limit = hlimit;
1119                 np->cork.tclass = tclass;
1120                 mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
1121                       rt->u.dst.dev->mtu : dst_mtu(rt->u.dst.path);
1122                 if (np->frag_size < mtu) {
1123                         if (np->frag_size)
1124                                 mtu = np->frag_size;
1125                 }
1126                 inet->cork.fragsize = mtu;
1127                 if (dst_allfrag(rt->u.dst.path))
1128                         inet->cork.flags |= IPCORK_ALLFRAG;
1129                 inet->cork.length = 0;
1130                 sk->sk_sndmsg_page = NULL;
1131                 sk->sk_sndmsg_off = 0;
1132                 exthdrlen = rt->u.dst.header_len + (opt ? opt->opt_flen : 0) -
1133                             rt->rt6i_nfheader_len;
1134                 length += exthdrlen;
1135                 transhdrlen += exthdrlen;
1136         } else {
1137                 rt = np->cork.rt;
1138                 fl = &inet->cork.fl;
1139                 if (inet->cork.flags & IPCORK_OPT)
1140                         opt = np->cork.opt;
1141                 transhdrlen = 0;
1142                 exthdrlen = 0;
1143                 mtu = inet->cork.fragsize;
1144         }
1145
1146         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1147
1148         fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
1149                         (opt ? opt->opt_nflen : 0);
1150         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - sizeof(struct frag_hdr);
1151
1152         if (mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN) {
1153                 if (inet->cork.length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN - fragheaderlen) {
1154                         ipv6_local_error(sk, EMSGSIZE, fl, mtu-exthdrlen);
1155                         return -EMSGSIZE;
1156                 }
1157         }
1158
1159         /*
1160          * Let's try using as much space as possible.
1161          * Use MTU if total length of the message fits into the MTU.
1162          * Otherwise, we need to reserve fragment header and
1163          * fragment alignment (= 8-15 octects, in total).
1164          *
1165          * Note that we may need to "move" the data from the tail of
1166          * of the buffer to the new fragment when we split
1167          * the message.
1168          *
1169          * FIXME: It may be fragmented into multiple chunks
1170          *        at once if non-fragmentable extension headers
1171          *        are too large.
1172          * --yoshfuji
1173          */
1174
1175         inet->cork.length += length;
1176         if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
1177             (rt->u.dst.dev->features & NETIF_F_UFO)) {
1178
1179                 err = ip6_ufo_append_data(sk, getfrag, from, length, hh_len,
1180                                           fragheaderlen, transhdrlen, mtu,
1181                                           flags);
1182                 if (err)
1183                         goto error;
1184                 return 0;
1185         }
1186
1187         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1188                 goto alloc_new_skb;
1189
1190         while (length > 0) {
1191                 /* Check if the remaining data fits into current packet. */
1192                 copy = (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
1193                 if (copy < length)
1194                         copy = maxfraglen - skb->len;
1195
1196                 if (copy <= 0) {
1197                         char *data;
1198                         unsigned int datalen;
1199                         unsigned int fraglen;
1200                         unsigned int fraggap;
1201                         unsigned int alloclen;
1202                         struct sk_buff *skb_prev;
1203 alloc_new_skb:
1204                         skb_prev = skb;
1205
1206                         /* There's no room in the current skb */
1207                         if (skb_prev)
1208                                 fraggap = skb_prev->len - maxfraglen;
1209                         else
1210                                 fraggap = 0;
1211
1212                         /*
1213                          * If remaining data exceeds the mtu,
1214                          * we know we need more fragment(s).
1215                          */
1216                         datalen = length + fraggap;
1217                         if (datalen > (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
1218                                 datalen = maxfraglen - fragheaderlen;
1219
1220                         fraglen = datalen + fragheaderlen;
1221                         if ((flags & MSG_MORE) &&
1222                             !(rt->u.dst.dev->features&NETIF_F_SG))
1223                                 alloclen = mtu;
1224                         else
1225                                 alloclen = datalen + fragheaderlen;
1226
1227                         /*
1228                          * The last fragment gets additional space at tail.
1229                          * Note: we overallocate on fragments with MSG_MODE
1230                          * because we have no idea if we're the last one.
1231                          */
1232                         if (datalen == length + fraggap)
1233                                 alloclen += rt->u.dst.trailer_len;
1234
1235                         /*
1236                          * We just reserve space for fragment header.
1237                          * Note: this may be overallocation if the message
1238                          * (without MSG_MORE) fits into the MTU.
1239                          */
1240                         alloclen += sizeof(struct frag_hdr);
1241
1242                         if (transhdrlen) {
1243                                 skb = sock_alloc_send_skb(sk,
1244                                                 alloclen + hh_len,
1245                                                 (flags & MSG_DONTWAIT), &err);
1246                         } else {
1247                                 skb = NULL;
1248                                 if (atomic_read(&sk->sk_wmem_alloc) <=
1249                                     2 * sk->sk_sndbuf)
1250                                         skb = sock_wmalloc(sk,
1251                                                            alloclen + hh_len, 1,
1252                                                            sk->sk_allocation);
1253                                 if (unlikely(skb == NULL))
1254                                         err = -ENOBUFS;
1255                         }
1256                         if (skb == NULL)
1257                                 goto error;
1258                         /*
1259                          *      Fill in the control structures
1260                          */
1261                         skb->ip_summed = csummode;
1262                         skb->csum = 0;
1263                         /* reserve for fragmentation */
1264                         skb_reserve(skb, hh_len+sizeof(struct frag_hdr));
1265
1266                         /*
1267                          *      Find where to start putting bytes
1268                          */
1269                         data = skb_put(skb, fraglen);
1270                         skb_set_network_header(skb, exthdrlen);
1271                         data += fragheaderlen;
1272                         skb->transport_header = (skb->network_header +
1273                                                  fragheaderlen);
1274                         if (fraggap) {
1275                                 skb->csum = skb_copy_and_csum_bits(
1276                                         skb_prev, maxfraglen,
1277                                         data + transhdrlen, fraggap, 0);
1278                                 skb_prev->csum = csum_sub(skb_prev->csum,
1279                                                           skb->csum);
1280                                 data += fraggap;
1281                                 pskb_trim_unique(skb_prev, maxfraglen);
1282                         }
1283                         copy = datalen - transhdrlen - fraggap;
1284                         if (copy < 0) {
1285                                 err = -EINVAL;
1286                                 kfree_skb(skb);
1287                                 goto error;
1288                         } else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
1289                                 err = -EFAULT;
1290                                 kfree_skb(skb);
1291                                 goto error;
1292                         }
1293
1294                         offset += copy;
1295                         length -= datalen - fraggap;
1296                         transhdrlen = 0;
1297                         exthdrlen = 0;
1298                         csummode = CHECKSUM_NONE;
1299
1300                         /*
1301                          * Put the packet on the pending queue
1302                          */
1303                         __skb_queue_tail(&sk->sk_write_queue, skb);
1304                         continue;
1305                 }
1306
1307                 if (copy > length)
1308                         copy = length;
1309
1310                 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
1311                         unsigned int off;
1312
1313                         off = skb->len;
1314                         if (getfrag(from, skb_put(skb, copy),
1315                                                 offset, copy, off, skb) < 0) {
1316                                 __skb_trim(skb, off);
1317                                 err = -EFAULT;
1318                                 goto error;
1319                         }
1320                 } else {
1321                         int i = skb_shinfo(skb)->nr_frags;
1322                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
1323                         struct page *page = sk->sk_sndmsg_page;
1324                         int off = sk->sk_sndmsg_off;
1325                         unsigned int left;
1326
1327                         if (page && (left = PAGE_SIZE - off) > 0) {
1328                                 if (copy >= left)
1329                                         copy = left;
1330                                 if (page != frag->page) {
1331                                         if (i == MAX_SKB_FRAGS) {
1332                                                 err = -EMSGSIZE;
1333                                                 goto error;
1334                                         }
1335                                         get_page(page);
1336                                         skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
1337                                         frag = &skb_shinfo(skb)->frags[i];
1338                                 }
1339                         } else if(i < MAX_SKB_FRAGS) {
1340                                 if (copy > PAGE_SIZE)
1341                                         copy = PAGE_SIZE;
1342                                 page = alloc_pages(sk->sk_allocation, 0);
1343                                 if (page == NULL) {
1344                                         err = -ENOMEM;
1345                                         goto error;
1346                                 }
1347                                 sk->sk_sndmsg_page = page;
1348                                 sk->sk_sndmsg_off = 0;
1349
1350                                 skb_fill_page_desc(skb, i, page, 0, 0);
1351                                 frag = &skb_shinfo(skb)->frags[i];
1352                         } else {
1353                                 err = -EMSGSIZE;
1354                                 goto error;
1355                         }
1356                         if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1357                                 err = -EFAULT;
1358                                 goto error;
1359                         }
1360                         sk->sk_sndmsg_off += copy;
1361                         frag->size += copy;
1362                         skb->len += copy;
1363                         skb->data_len += copy;
1364                         skb->truesize += copy;
1365                         atomic_add(copy, &sk->sk_wmem_alloc);
1366                 }
1367                 offset += copy;
1368                 length -= copy;
1369         }
1370         return 0;
1371 error:
1372         inet->cork.length -= length;
1373         IP6_INC_STATS(rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
1374         return err;
1375 }
1376
1377 static void ip6_cork_release(struct inet_sock *inet, struct ipv6_pinfo *np)
1378 {
1379         inet->cork.flags &= ~IPCORK_OPT;
1380         kfree(np->cork.opt);
1381         np->cork.opt = NULL;
1382         if (np->cork.rt) {
1383                 dst_release(&np->cork.rt->u.dst);
1384                 np->cork.rt = NULL;
1385                 inet->cork.flags &= ~IPCORK_ALLFRAG;
1386         }
1387         memset(&inet->cork.fl, 0, sizeof(inet->cork.fl));
1388 }
1389
1390 int ip6_push_pending_frames(struct sock *sk)
1391 {
1392         struct sk_buff *skb, *tmp_skb;
1393         struct sk_buff **tail_skb;
1394         struct in6_addr final_dst_buf, *final_dst = &final_dst_buf;
1395         struct inet_sock *inet = inet_sk(sk);
1396         struct ipv6_pinfo *np = inet6_sk(sk);
1397         struct ipv6hdr *hdr;
1398         struct ipv6_txoptions *opt = np->cork.opt;
1399         struct rt6_info *rt = np->cork.rt;
1400         struct flowi *fl = &inet->cork.fl;
1401         unsigned char proto = fl->proto;
1402         int err = 0;
1403
1404         if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1405                 goto out;
1406         tail_skb = &(skb_shinfo(skb)->frag_list);
1407
1408         /* move skb->data to ip header from ext header */
1409         if (skb->data < skb_network_header(skb))
1410                 __skb_pull(skb, skb_network_offset(skb));
1411         while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1412                 __skb_pull(tmp_skb, skb_network_header_len(skb));
1413                 *tail_skb = tmp_skb;
1414                 tail_skb = &(tmp_skb->next);
1415                 skb->len += tmp_skb->len;
1416                 skb->data_len += tmp_skb->len;
1417                 skb->truesize += tmp_skb->truesize;
1418                 __sock_put(tmp_skb->sk);
1419                 tmp_skb->destructor = NULL;
1420                 tmp_skb->sk = NULL;
1421         }
1422
1423         ipv6_addr_copy(final_dst, &fl->fl6_dst);
1424         __skb_pull(skb, skb_network_header_len(skb));
1425         if (opt && opt->opt_flen)
1426                 ipv6_push_frag_opts(skb, opt, &proto);
1427         if (opt && opt->opt_nflen)
1428                 ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst);
1429
1430         skb_push(skb, sizeof(struct ipv6hdr));
1431         skb_reset_network_header(skb);
1432         hdr = ipv6_hdr(skb);
1433
1434         *(__be32*)hdr = fl->fl6_flowlabel |
1435                      htonl(0x60000000 | ((int)np->cork.tclass << 20));
1436
1437         hdr->hop_limit = np->cork.hop_limit;
1438         hdr->nexthdr = proto;
1439         ipv6_addr_copy(&hdr->saddr, &fl->fl6_src);
1440         ipv6_addr_copy(&hdr->daddr, final_dst);
1441
1442         skb->priority = sk->sk_priority;
1443         skb->mark = sk->sk_mark;
1444
1445         skb->dst = dst_clone(&rt->u.dst);
1446         IP6_INC_STATS(rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
1447         if (proto == IPPROTO_ICMPV6) {
1448                 struct inet6_dev *idev = ip6_dst_idev(skb->dst);
1449
1450                 ICMP6MSGOUT_INC_STATS_BH(idev, icmp6_hdr(skb)->icmp6_type);
1451                 ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTMSGS);
1452         }
1453
1454         err = ip6_local_out(skb);
1455         if (err) {
1456                 if (err > 0)
1457                         err = np->recverr ? net_xmit_errno(err) : 0;
1458                 if (err)
1459                         goto error;
1460         }
1461
1462 out:
1463         ip6_cork_release(inet, np);
1464         return err;
1465 error:
1466         goto out;
1467 }
1468
1469 void ip6_flush_pending_frames(struct sock *sk)
1470 {
1471         struct sk_buff *skb;
1472
1473         while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL) {
1474                 if (skb->dst)
1475                         IP6_INC_STATS(ip6_dst_idev(skb->dst),
1476                                       IPSTATS_MIB_OUTDISCARDS);
1477                 kfree_skb(skb);
1478         }
1479
1480         ip6_cork_release(inet_sk(sk), inet6_sk(sk));
1481 }