net/ipv4/ip_output.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              The Internet Protocol (IP) output module.
   7  *
   8  * Version:     $Id: ip_output.c,v 1.100 2002/02/01 22:01:03 davem Exp $
   9  *
  10  * Authors:     Ross Biro
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Donald Becker, <becker@super.org>
  13  *              Alan Cox, <Alan.Cox@linux.org>
  14  *              Richard Underwood
  15  *              Stefan Becker, <stefanb@yello.ping.de>
  16  *              Jorge Cwik, <jorge@laser.satlink.net>
  17  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  18  *              Hirokazu Takahashi, <taka@valinux.co.jp>
  19  *
  20  *      See ip_input.c for original log
  21  *
  22  *      Fixes:
  23  *              Alan Cox        :       Missing nonblock feature in ip_build_xmit.
  24  *              Mike Kilburn    :       htons() missing in ip_build_xmit.
  25  *              Bradford Johnson:       Fix faulty handling of some frames when
  26  *                                      no route is found.
  27  *              Alexander Demenshin:    Missing sk/skb free in ip_queue_xmit
  28  *                                      (in case if packet not accepted by
  29  *                                      output firewall rules)
  30  *              Mike McLagan    :       Routing by source
  31  *              Alexey Kuznetsov:       use new route cache
  32  *              Andi Kleen:             Fix broken PMTU recovery and remove
  33  *                                      some redundant tests.
  34  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  35  *              Andi Kleen      :       Replace ip_reply with ip_send_reply.
  36  *              Andi Kleen      :       Split fast and slow ip_build_xmit path
  37  *                                      for decreased register pressure on x86
  38  *                                      and more readibility.
  39  *              Marc Boucher    :       When call_out_firewall returns FW_QUEUE,
  40  *                                      silently drop skb instead of failing with -EPERM.
  41  *              Detlev Wengorz  :       Copy protocol for fragments.
  42  *              Hirokazu Takahashi:     HW checksumming for outgoing UDP
  43  *                                      datagrams.
  44  *              Hirokazu Takahashi:     sendfile() on UDP works now.
  45  */
  46
  47 #include <asm/uaccess.h>
  48 #include <asm/system.h>
  49 #include <linux/module.h>
  50 #include <linux/types.h>
  51 #include <linux/kernel.h>
  52 #include <linux/mm.h>
  53 #include <linux/string.h>
  54 #include <linux/errno.h>
  55 #include <linux/highmem.h>
  56
  57 #include <linux/socket.h>
  58 #include <linux/sockios.h>
  59 #include <linux/in.h>
  60 #include <linux/inet.h>
  61 #include <linux/netdevice.h>
  62 #include <linux/etherdevice.h>
  63 #include <linux/proc_fs.h>
  64 #include <linux/stat.h>
  65 #include <linux/init.h>
  66
  67 #include <net/snmp.h>
  68 #include <net/ip.h>
  69 #include <net/protocol.h>
  70 #include <net/route.h>
  71 #include <net/xfrm.h>
  72 #include <linux/skbuff.h>
  73 #include <net/sock.h>
  74 #include <net/arp.h>
  75 #include <net/icmp.h>
  76 #include <net/checksum.h>
  77 #include <net/inetpeer.h>
  78 #include <net/checksum.h>
  79 #include <linux/igmp.h>
  80 #include <linux/netfilter_ipv4.h>
  81 #include <linux/netfilter_bridge.h>
  82 #include <linux/mroute.h>
  83 #include <linux/netlink.h>
  84 #include <linux/tcp.h>
  85
  86 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
  87
  88 /* Generate a checksum for an outgoing IP datagram. */
  89 __inline__ void ip_send_check(struct iphdr *iph)
  90 {
  91         iph->check = 0;
  92         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  93 }
  94
  95 /* dev_loopback_xmit for use with netfilter. */
  96 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
  97 {
  98         skb_reset_mac_header(newskb);
  99         __skb_pull(newskb, newskb->nh.raw - newskb->data);
 100         newskb->pkt_type = PACKET_LOOPBACK;
 101         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 102         BUG_TRAP(newskb->dst);
 103         netif_rx(newskb);
 104         return 0;
 105 }
 106
 107 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 108 {
 109         int ttl = inet->uc_ttl;
 110
 111         if (ttl < 0)
 112                 ttl = dst_metric(dst, RTAX_HOPLIMIT);
 113         return ttl;
 114 }
 115
 116 /*
 117  *              Add an ip header to a skbuff and send it out.
 118  *
 119  */
 120 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 121                           __be32 saddr, __be32 daddr, struct ip_options *opt)
 122 {
 123         struct inet_sock *inet = inet_sk(sk);
 124         struct rtable *rt = (struct rtable *)skb->dst;
 125         struct iphdr *iph;
 126
 127         /* Build the IP header. */
 128         if (opt)
 129                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr) + opt->optlen);
 130         else
 131                 iph=(struct iphdr *)skb_push(skb,sizeof(struct iphdr));
 132
 133         iph->version  = 4;
 134         iph->ihl      = 5;
 135         iph->tos      = inet->tos;
 136         if (ip_dont_fragment(sk, &rt->u.dst))
 137                 iph->frag_off = htons(IP_DF);
 138         else
 139                 iph->frag_off = 0;
 140         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 141         iph->daddr    = rt->rt_dst;
 142         iph->saddr    = rt->rt_src;
 143         iph->protocol = sk->sk_protocol;
 144         iph->tot_len  = htons(skb->len);
 145         ip_select_ident(iph, &rt->u.dst, sk);
 146         skb->nh.iph   = iph;
 147
 148         if (opt && opt->optlen) {
 149                 iph->ihl += opt->optlen>>2;
 150                 ip_options_build(skb, opt, daddr, rt, 0);
 151         }
 152         ip_send_check(iph);
 153
 154         skb->priority = sk->sk_priority;
 155
 156         /* Send it out. */
 157         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 158                        dst_output);
 159 }
 160
 161 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 162
 163 static inline int ip_finish_output2(struct sk_buff *skb)
 164 {
 165         struct dst_entry *dst = skb->dst;
 166         struct net_device *dev = dst->dev;
 167         int hh_len = LL_RESERVED_SPACE(dev);
 168
 169         /* Be paranoid, rather than too clever. */
 170         if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
 171                 struct sk_buff *skb2;
 172
 173                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 174                 if (skb2 == NULL) {
 175                         kfree_skb(skb);
 176                         return -ENOMEM;
 177                 }
 178                 if (skb->sk)
 179                         skb_set_owner_w(skb2, skb->sk);
 180                 kfree_skb(skb);
 181                 skb = skb2;
 182         }
 183
 184         if (dst->hh)
 185                 return neigh_hh_output(dst->hh, skb);
 186         else if (dst->neighbour)
 187                 return dst->neighbour->output(skb);
 188
 189         if (net_ratelimit())
 190                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 191         kfree_skb(skb);
 192         return -EINVAL;
 193 }
 194
 195 static inline int ip_finish_output(struct sk_buff *skb)
 196 {
 197 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 198         /* Policy lookup after SNAT yielded a new policy */
 199         if (skb->dst->xfrm != NULL) {
 200                 IPCB(skb)->flags |= IPSKB_REROUTED;
 201                 return dst_output(skb);
 202         }
 203 #endif
 204         if (skb->len > dst_mtu(skb->dst) && !skb_is_gso(skb))
 205                 return ip_fragment(skb, ip_finish_output2);
 206         else
 207                 return ip_finish_output2(skb);
 208 }
 209
 210 int ip_mc_output(struct sk_buff *skb)
 211 {
 212         struct sock *sk = skb->sk;
 213         struct rtable *rt = (struct rtable*)skb->dst;
 214         struct net_device *dev = rt->u.dst.dev;
 215
 216         /*
 217          *      If the indicated interface is up and running, send the packet.
 218          */
 219         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 220
 221         skb->dev = dev;
 222         skb->protocol = htons(ETH_P_IP);
 223
 224         /*
 225          *      Multicasts are looped back for other local users
 226          */
 227
 228         if (rt->rt_flags&RTCF_MULTICAST) {
 229                 if ((!sk || inet_sk(sk)->mc_loop)
 230 #ifdef CONFIG_IP_MROUTE
 231                 /* Small optimization: do not loopback not local frames,
 232                    which returned after forwarding; they will be  dropped
 233                    by ip_mr_input in any case.
 234                    Note, that local frames are looped back to be delivered
 235                    to local recipients.
 236
 237                    This check is duplicated in ip_mr_input at the moment.
 238                  */
 239                     && ((rt->rt_flags&RTCF_LOCAL) || !(IPCB(skb)->flags&IPSKB_FORWARDED))
 240 #endif
 241                 ) {
 242                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 243                         if (newskb)
 244                                 NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 245                                         newskb->dev,
 246                                         ip_dev_loopback_xmit);
 247                 }
 248
 249                 /* Multicasts with ttl 0 must not go beyond the host */
 250
 251                 if (skb->nh.iph->ttl == 0) {
 252                         kfree_skb(skb);
 253                         return 0;
 254                 }
 255         }
 256
 257         if (rt->rt_flags&RTCF_BROADCAST) {
 258                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 259                 if (newskb)
 260                         NF_HOOK(PF_INET, NF_IP_POST_ROUTING, newskb, NULL,
 261                                 newskb->dev, ip_dev_loopback_xmit);
 262         }
 263
 264         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dev,
 265                             ip_finish_output,
 266                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 267 }
 268
 269 int ip_output(struct sk_buff *skb)
 270 {
 271         struct net_device *dev = skb->dst->dev;
 272
 273         IP_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
 274
 275         skb->dev = dev;
 276         skb->protocol = htons(ETH_P_IP);
 277
 278         return NF_HOOK_COND(PF_INET, NF_IP_POST_ROUTING, skb, NULL, dev,
 279                             ip_finish_output,
 280                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 281 }
 282
 283 int ip_queue_xmit(struct sk_buff *skb, int ipfragok)
 284 {
 285         struct sock *sk = skb->sk;
 286         struct inet_sock *inet = inet_sk(sk);
 287         struct ip_options *opt = inet->opt;
 288         struct rtable *rt;
 289         struct iphdr *iph;
 290
 291         /* Skip all of this if the packet is already routed,
 292          * f.e. by something like SCTP.
 293          */
 294         rt = (struct rtable *) skb->dst;
 295         if (rt != NULL)
 296                 goto packet_routed;
 297
 298         /* Make sure we can route this packet. */
 299         rt = (struct rtable *)__sk_dst_check(sk, 0);
 300         if (rt == NULL) {
 301                 __be32 daddr;
 302
 303                 /* Use correct destination address if we have options. */
 304                 daddr = inet->daddr;
 305                 if(opt && opt->srr)
 306                         daddr = opt->faddr;
 307
 308                 {
 309                         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 310                                             .nl_u = { .ip4_u =
 311                                                       { .daddr = daddr,
 312                                                         .saddr = inet->saddr,
 313                                                         .tos = RT_CONN_FLAGS(sk) } },
 314                                             .proto = sk->sk_protocol,
 315                                             .uli_u = { .ports =
 316                                                        { .sport = inet->sport,
 317                                                          .dport = inet->dport } } };
 318
 319                         /* If this fails, retransmit mechanism of transport layer will
 320                          * keep trying until route appears or the connection times
 321                          * itself out.
 322                          */
 323                         security_sk_classify_flow(sk, &fl);
 324                         if (ip_route_output_flow(&rt, &fl, sk, 0))
 325                                 goto no_route;
 326                 }
 327                 sk_setup_caps(sk, &rt->u.dst);
 328         }
 329         skb->dst = dst_clone(&rt->u.dst);
 330
 331 packet_routed:
 332         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
 333                 goto no_route;
 334
 335         /* OK, we know where to send it, allocate and build IP header. */
 336         iph = (struct iphdr *) skb_push(skb, sizeof(struct iphdr) + (opt ? opt->optlen : 0));
 337         *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 338         iph->tot_len = htons(skb->len);
 339         if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
 340                 iph->frag_off = htons(IP_DF);
 341         else
 342                 iph->frag_off = 0;
 343         iph->ttl      = ip_select_ttl(inet, &rt->u.dst);
 344         iph->protocol = sk->sk_protocol;
 345         iph->saddr    = rt->rt_src;
 346         iph->daddr    = rt->rt_dst;
 347         skb->nh.iph   = iph;
 348         /* Transport layer set skb->h.foo itself. */
 349
 350         if (opt && opt->optlen) {
 351                 iph->ihl += opt->optlen >> 2;
 352                 ip_options_build(skb, opt, inet->daddr, rt, 0);
 353         }
 354
 355         ip_select_ident_more(iph, &rt->u.dst, sk,
 356                              (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 357
 358         /* Add an IP checksum. */
 359         ip_send_check(iph);
 360
 361         skb->priority = sk->sk_priority;
 362
 363         return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
 364                        dst_output);
 365
 366 no_route:
 367         IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
 368         kfree_skb(skb);
 369         return -EHOSTUNREACH;
 370 }
 371
 372
 373 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 374 {
 375         to->pkt_type = from->pkt_type;
 376         to->priority = from->priority;
 377         to->protocol = from->protocol;
 378         dst_release(to->dst);
 379         to->dst = dst_clone(from->dst);
 380         to->dev = from->dev;
 381         to->mark = from->mark;
 382
 383         /* Copy the flags to each fragment. */
 384         IPCB(to)->flags = IPCB(from)->flags;
 385
 386 #ifdef CONFIG_NET_SCHED
 387         to->tc_index = from->tc_index;
 388 #endif
 389 #ifdef CONFIG_NETFILTER
 390         /* Connection association is same as pre-frag packet */
 391         nf_conntrack_put(to->nfct);
 392         to->nfct = from->nfct;
 393         nf_conntrack_get(to->nfct);
 394         to->nfctinfo = from->nfctinfo;
 395 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 396         to->ipvs_property = from->ipvs_property;
 397 #endif
 398 #ifdef CONFIG_BRIDGE_NETFILTER
 399         nf_bridge_put(to->nf_bridge);
 400         to->nf_bridge = from->nf_bridge;
 401         nf_bridge_get(to->nf_bridge);
 402 #endif
 403 #endif
 404         skb_copy_secmark(to, from);
 405 }
 406
 407 /*
 408  *      This IP datagram is too large to be sent in one piece.  Break it up into
 409  *      smaller pieces (each of size equal to IP header plus
 410  *      a block of the data of the original IP data part) that will yet fit in a
 411  *      single device frame, and queue such a frame for sending.
 412  */
 413
 414 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*))
 415 {
 416         struct iphdr *iph;
 417         int raw = 0;
 418         int ptr;
 419         struct net_device *dev;
 420         struct sk_buff *skb2;
 421         unsigned int mtu, hlen, left, len, ll_rs, pad;
 422         int offset;
 423         __be16 not_last_frag;
 424         struct rtable *rt = (struct rtable*)skb->dst;
 425         int err = 0;
 426
 427         dev = rt->u.dst.dev;
 428
 429         /*
 430          *      Point into the IP datagram header.
 431          */
 432
 433         iph = skb->nh.iph;
 434
 435         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 436                 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 437                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 438                           htonl(dst_mtu(&rt->u.dst)));
 439                 kfree_skb(skb);
 440                 return -EMSGSIZE;
 441         }
 442
 443         /*
 444          *      Setup starting values.
 445          */
 446
 447         hlen = iph->ihl * 4;
 448         mtu = dst_mtu(&rt->u.dst) - hlen;       /* Size of data space */
 449         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 450
 451         /* When frag_list is given, use it. First, check its validity:
 452          * some transformers could create wrong frag_list or break existing
 453          * one, it is not prohibited. In this case fall back to copying.
 454          *
 455          * LATER: this step can be merged to real generation of fragments,
 456          * we can switch to copy when see the first bad fragment.
 457          */
 458         if (skb_shinfo(skb)->frag_list) {
 459                 struct sk_buff *frag;
 460                 int first_len = skb_pagelen(skb);
 461
 462                 if (first_len - hlen > mtu ||
 463                     ((first_len - hlen) & 7) ||
 464                     (iph->frag_off & htons(IP_MF|IP_OFFSET)) ||
 465                     skb_cloned(skb))
 466                         goto slow_path;
 467
 468                 for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next) {
 469                         /* Correct geometry. */
 470                         if (frag->len > mtu ||
 471                             ((frag->len & 7) && frag->next) ||
 472                             skb_headroom(frag) < hlen)
 473                             goto slow_path;
 474
 475                         /* Partially cloned skb? */
 476                         if (skb_shared(frag))
 477                                 goto slow_path;
 478
 479                         BUG_ON(frag->sk);
 480                         if (skb->sk) {
 481                                 sock_hold(skb->sk);
 482                                 frag->sk = skb->sk;
 483                                 frag->destructor = sock_wfree;
 484                                 skb->truesize -= frag->truesize;
 485                         }
 486                 }
 487
 488                 /* Everything is OK. Generate! */
 489
 490                 err = 0;
 491                 offset = 0;
 492                 frag = skb_shinfo(skb)->frag_list;
 493                 skb_shinfo(skb)->frag_list = NULL;
 494                 skb->data_len = first_len - skb_headlen(skb);
 495                 skb->len = first_len;
 496                 iph->tot_len = htons(first_len);
 497                 iph->frag_off = htons(IP_MF);
 498                 ip_send_check(iph);
 499
 500                 for (;;) {
 501                         /* Prepare header of the next frame,
 502                          * before previous one went down. */
 503                         if (frag) {
 504                                 frag->ip_summed = CHECKSUM_NONE;
 505                                 frag->h.raw = frag->data;
 506                                 __skb_push(frag, hlen);
 507                                 skb_reset_network_header(frag);
 508                                 memcpy(frag->nh.raw, iph, hlen);
 509                                 iph = frag->nh.iph;
 510                                 iph->tot_len = htons(frag->len);
 511                                 ip_copy_metadata(frag, skb);
 512                                 if (offset == 0)
 513                                         ip_options_fragment(frag);
 514                                 offset += skb->len - hlen;
 515                                 iph->frag_off = htons(offset>>3);
 516                                 if (frag->next != NULL)
 517                                         iph->frag_off |= htons(IP_MF);
 518                                 /* Ready, complete checksum */
 519                                 ip_send_check(iph);
 520                         }
 521
 522                         err = output(skb);
 523
 524                         if (!err)
 525                                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 526                         if (err || !frag)
 527                                 break;
 528
 529                         skb = frag;
 530                         frag = skb->next;
 531                         skb->next = NULL;
 532                 }
 533
 534                 if (err == 0) {
 535                         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 536                         return 0;
 537                 }
 538
 539                 while (frag) {
 540                         skb = frag->next;
 541                         kfree_skb(frag);
 542                         frag = skb;
 543                 }
 544                 IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 545                 return err;
 546         }
 547
 548 slow_path:
 549         left = skb->len - hlen;         /* Space per frame */
 550         ptr = raw + hlen;               /* Where to start from */
 551
 552         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 553          * we need to make room for the encapsulating header
 554          */
 555         pad = nf_bridge_pad(skb);
 556         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->u.dst.dev, pad);
 557         mtu -= pad;
 558
 559         /*
 560          *      Fragment the datagram.
 561          */
 562
 563         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 564         not_last_frag = iph->frag_off & htons(IP_MF);
 565
 566         /*
 567          *      Keep copying data until we run out.
 568          */
 569
 570         while (left > 0) {
 571                 len = left;
 572                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 573                 if (len > mtu)
 574                         len = mtu;
 575                 /* IF: we are not sending upto and including the packet end
 576                    then align the next start on an eight byte boundary */
 577                 if (len < left) {
 578                         len &= ~7;
 579                 }
 580                 /*
 581                  *      Allocate buffer.
 582                  */
 583
 584                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 585                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 586                         err = -ENOMEM;
 587                         goto fail;
 588                 }
 589
 590                 /*
 591                  *      Set up data on packet
 592                  */
 593
 594                 ip_copy_metadata(skb2, skb);
 595                 skb_reserve(skb2, ll_rs);
 596                 skb_put(skb2, len + hlen);
 597                 skb_reset_network_header(skb2);
 598                 skb2->h.raw = skb2->data + hlen;
 599
 600                 /*
 601                  *      Charge the memory for the fragment to any owner
 602                  *      it might possess
 603                  */
 604
 605                 if (skb->sk)
 606                         skb_set_owner_w(skb2, skb->sk);
 607
 608                 /*
 609                  *      Copy the packet header into the new buffer.
 610                  */
 611
 612                 memcpy(skb2->nh.raw, skb->data, hlen);
 613
 614                 /*
 615                  *      Copy a block of the IP datagram.
 616                  */
 617                 if (skb_copy_bits(skb, ptr, skb2->h.raw, len))
 618                         BUG();
 619                 left -= len;
 620
 621                 /*
 622                  *      Fill in the new header fields.
 623                  */
 624                 iph = skb2->nh.iph;
 625                 iph->frag_off = htons((offset >> 3));
 626
 627                 /* ANK: dirty, but effective trick. Upgrade options only if
 628                  * the segment to be fragmented was THE FIRST (otherwise,
 629                  * options are already fixed) and make it ONCE
 630                  * on the initial skb, so that all the following fragments
 631                  * will inherit fixed options.
 632                  */
 633                 if (offset == 0)
 634                         ip_options_fragment(skb);
 635
 636                 /*
 637                  *      Added AC : If we are fragmenting a fragment that's not the
 638                  *                 last fragment then keep MF on each bit
 639                  */
 640                 if (left > 0 || not_last_frag)
 641                         iph->frag_off |= htons(IP_MF);
 642                 ptr += len;
 643                 offset += len;
 644
 645                 /*
 646                  *      Put this fragment into the sending queue.
 647                  */
 648                 iph->tot_len = htons(len + hlen);
 649
 650                 ip_send_check(iph);
 651
 652                 err = output(skb2);
 653                 if (err)
 654                         goto fail;
 655
 656                 IP_INC_STATS(IPSTATS_MIB_FRAGCREATES);
 657         }
 658         kfree_skb(skb);
 659         IP_INC_STATS(IPSTATS_MIB_FRAGOKS);
 660         return err;
 661
 662 fail:
 663         kfree_skb(skb);
 664         IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
 665         return err;
 666 }
 667
 668 EXPORT_SYMBOL(ip_fragment);
 669
 670 int
 671 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 672 {
 673         struct iovec *iov = from;
 674
 675         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 676                 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 677                         return -EFAULT;
 678         } else {
 679                 __wsum csum = 0;
 680                 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 681                         return -EFAULT;
 682                 skb->csum = csum_block_add(skb->csum, csum, odd);
 683         }
 684         return 0;
 685 }
 686
 687 static inline __wsum
 688 csum_page(struct page *page, int offset, int copy)
 689 {
 690         char *kaddr;
 691         __wsum csum;
 692         kaddr = kmap(page);
 693         csum = csum_partial(kaddr + offset, copy, 0);
 694         kunmap(page);
 695         return csum;
 696 }
 697
 698 static inline int ip_ufo_append_data(struct sock *sk,
 699                         int getfrag(void *from, char *to, int offset, int len,
 700                                int odd, struct sk_buff *skb),
 701                         void *from, int length, int hh_len, int fragheaderlen,
 702                         int transhdrlen, int mtu,unsigned int flags)
 703 {
 704         struct sk_buff *skb;
 705         int err;
 706
 707         /* There is support for UDP fragmentation offload by network
 708          * device, so create one single skb packet containing complete
 709          * udp datagram
 710          */
 711         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
 712                 skb = sock_alloc_send_skb(sk,
 713                         hh_len + fragheaderlen + transhdrlen + 20,
 714                         (flags & MSG_DONTWAIT), &err);
 715
 716                 if (skb == NULL)
 717                         return err;
 718
 719                 /* reserve space for Hardware header */
 720                 skb_reserve(skb, hh_len);
 721
 722                 /* create space for UDP/IP header */
 723                 skb_put(skb,fragheaderlen + transhdrlen);
 724
 725                 /* initialize network header pointer */
 726                 skb_reset_network_header(skb);
 727
 728                 /* initialize protocol header pointer */
 729                 skb->h.raw = skb->data + fragheaderlen;
 730
 731                 skb->ip_summed = CHECKSUM_PARTIAL;
 732                 skb->csum = 0;
 733                 sk->sk_sndmsg_off = 0;
 734         }
 735
 736         err = skb_append_datato_frags(sk,skb, getfrag, from,
 737                                (length - transhdrlen));
 738         if (!err) {
 739                 /* specify the length of each IP datagram fragment*/
 740                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
 741                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 742                 __skb_queue_tail(&sk->sk_write_queue, skb);
 743
 744                 return 0;
 745         }
 746         /* There is not enough support do UFO ,
 747          * so follow normal path
 748          */
 749         kfree_skb(skb);
 750         return err;
 751 }
 752
 753 /*
 754  *      ip_append_data() and ip_append_page() can make one large IP datagram
 755  *      from many pieces of data. Each pieces will be holded on the socket
 756  *      until ip_push_pending_frames() is called. Each piece can be a page
 757  *      or non-page data.
 758  *
 759  *      Not only UDP, other transport protocols - e.g. raw sockets - can use
 760  *      this interface potentially.
 761  *
 762  *      LATER: length must be adjusted by pad at tail, when it is required.
 763  */
 764 int ip_append_data(struct sock *sk,
 765                    int getfrag(void *from, char *to, int offset, int len,
 766                                int odd, struct sk_buff *skb),
 767                    void *from, int length, int transhdrlen,
 768                    struct ipcm_cookie *ipc, struct rtable *rt,
 769                    unsigned int flags)
 770 {
 771         struct inet_sock *inet = inet_sk(sk);
 772         struct sk_buff *skb;
 773
 774         struct ip_options *opt = NULL;
 775         int hh_len;
 776         int exthdrlen;
 777         int mtu;
 778         int copy;
 779         int err;
 780         int offset = 0;
 781         unsigned int maxfraglen, fragheaderlen;
 782         int csummode = CHECKSUM_NONE;
 783
 784         if (flags&MSG_PROBE)
 785                 return 0;
 786
 787         if (skb_queue_empty(&sk->sk_write_queue)) {
 788                 /*
 789                  * setup for corking.
 790                  */
 791                 opt = ipc->opt;
 792                 if (opt) {
 793                         if (inet->cork.opt == NULL) {
 794                                 inet->cork.opt = kmalloc(sizeof(struct ip_options) + 40, sk->sk_allocation);
 795                                 if (unlikely(inet->cork.opt == NULL))
 796                                         return -ENOBUFS;
 797                         }
 798                         memcpy(inet->cork.opt, opt, sizeof(struct ip_options)+opt->optlen);
 799                         inet->cork.flags |= IPCORK_OPT;
 800                         inet->cork.addr = ipc->addr;
 801                 }
 802                 dst_hold(&rt->u.dst);
 803                 inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path);
 804                 inet->cork.rt = rt;
 805                 inet->cork.length = 0;
 806                 sk->sk_sndmsg_page = NULL;
 807                 sk->sk_sndmsg_off = 0;
 808                 if ((exthdrlen = rt->u.dst.header_len) != 0) {
 809                         length += exthdrlen;
 810                         transhdrlen += exthdrlen;
 811                 }
 812         } else {
 813                 rt = inet->cork.rt;
 814                 if (inet->cork.flags & IPCORK_OPT)
 815                         opt = inet->cork.opt;
 816
 817                 transhdrlen = 0;
 818                 exthdrlen = 0;
 819                 mtu = inet->cork.fragsize;
 820         }
 821         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
 822
 823         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 824         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 825
 826         if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
 827                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu-exthdrlen);
 828                 return -EMSGSIZE;
 829         }
 830
 831         /*
 832          * transhdrlen > 0 means that this is the first fragment and we wish
 833          * it won't be fragmented in the future.
 834          */
 835         if (transhdrlen &&
 836             length + fragheaderlen <= mtu &&
 837             rt->u.dst.dev->features & NETIF_F_ALL_CSUM &&
 838             !exthdrlen)
 839                 csummode = CHECKSUM_PARTIAL;
 840
 841         inet->cork.length += length;
 842         if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
 843                         (rt->u.dst.dev->features & NETIF_F_UFO)) {
 844
 845                 err = ip_ufo_append_data(sk, getfrag, from, length, hh_len,
 846                                          fragheaderlen, transhdrlen, mtu,
 847                                          flags);
 848                 if (err)
 849                         goto error;
 850                 return 0;
 851         }
 852
 853         /* So, what's going on in the loop below?
 854          *
 855          * We use calculated fragment length to generate chained skb,
 856          * each of segments is IP fragment ready for sending to network after
 857          * adding appropriate IP header.
 858          */
 859
 860         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
 861                 goto alloc_new_skb;
 862
 863         while (length > 0) {
 864                 /* Check if the remaining data fits into current packet. */
 865                 copy = mtu - skb->len;
 866                 if (copy < length)
 867                         copy = maxfraglen - skb->len;
 868                 if (copy <= 0) {
 869                         char *data;
 870                         unsigned int datalen;
 871                         unsigned int fraglen;
 872                         unsigned int fraggap;
 873                         unsigned int alloclen;
 874                         struct sk_buff *skb_prev;
 875 alloc_new_skb:
 876                         skb_prev = skb;
 877                         if (skb_prev)
 878                                 fraggap = skb_prev->len - maxfraglen;
 879                         else
 880                                 fraggap = 0;
 881
 882                         /*
 883                          * If remaining data exceeds the mtu,
 884                          * we know we need more fragment(s).
 885                          */
 886                         datalen = length + fraggap;
 887                         if (datalen > mtu - fragheaderlen)
 888                                 datalen = maxfraglen - fragheaderlen;
 889                         fraglen = datalen + fragheaderlen;
 890
 891                         if ((flags & MSG_MORE) &&
 892                             !(rt->u.dst.dev->features&NETIF_F_SG))
 893                                 alloclen = mtu;
 894                         else
 895                                 alloclen = datalen + fragheaderlen;
 896
 897                         /* The last fragment gets additional space at tail.
 898                          * Note, with MSG_MORE we overallocate on fragments,
 899                          * because we have no idea what fragment will be
 900                          * the last.
 901                          */
 902                         if (datalen == length + fraggap)
 903                                 alloclen += rt->u.dst.trailer_len;
 904
 905                         if (transhdrlen) {
 906                                 skb = sock_alloc_send_skb(sk,
 907                                                 alloclen + hh_len + 15,
 908                                                 (flags & MSG_DONTWAIT), &err);
 909                         } else {
 910                                 skb = NULL;
 911                                 if (atomic_read(&sk->sk_wmem_alloc) <=
 912                                     2 * sk->sk_sndbuf)
 913                                         skb = sock_wmalloc(sk,
 914                                                            alloclen + hh_len + 15, 1,
 915                                                            sk->sk_allocation);
 916                                 if (unlikely(skb == NULL))
 917                                         err = -ENOBUFS;
 918                         }
 919                         if (skb == NULL)
 920                                 goto error;
 921
 922                         /*
 923                          *      Fill in the control structures
 924                          */
 925                         skb->ip_summed = csummode;
 926                         skb->csum = 0;
 927                         skb_reserve(skb, hh_len);
 928
 929                         /*
 930                          *      Find where to start putting bytes.
 931                          */
 932                         data = skb_put(skb, fraglen);
 933                         skb->nh.raw = data + exthdrlen;
 934                         data += fragheaderlen;
 935                         skb->h.raw = data + exthdrlen;
 936
 937                         if (fraggap) {
 938                                 skb->csum = skb_copy_and_csum_bits(
 939                                         skb_prev, maxfraglen,
 940                                         data + transhdrlen, fraggap, 0);
 941                                 skb_prev->csum = csum_sub(skb_prev->csum,
 942                                                           skb->csum);
 943                                 data += fraggap;
 944                                 pskb_trim_unique(skb_prev, maxfraglen);
 945                         }
 946
 947                         copy = datalen - transhdrlen - fraggap;
 948                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 949                                 err = -EFAULT;
 950                                 kfree_skb(skb);
 951                                 goto error;
 952                         }
 953
 954                         offset += copy;
 955                         length -= datalen - fraggap;
 956                         transhdrlen = 0;
 957                         exthdrlen = 0;
 958                         csummode = CHECKSUM_NONE;
 959
 960                         /*
 961                          * Put the packet on the pending queue.
 962                          */
 963                         __skb_queue_tail(&sk->sk_write_queue, skb);
 964                         continue;
 965                 }
 966
 967                 if (copy > length)
 968                         copy = length;
 969
 970                 if (!(rt->u.dst.dev->features&NETIF_F_SG)) {
 971                         unsigned int off;
 972
 973                         off = skb->len;
 974                         if (getfrag(from, skb_put(skb, copy),
 975                                         offset, copy, off, skb) < 0) {
 976                                 __skb_trim(skb, off);
 977                                 err = -EFAULT;
 978                                 goto error;
 979                         }
 980                 } else {
 981                         int i = skb_shinfo(skb)->nr_frags;
 982                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
 983                         struct page *page = sk->sk_sndmsg_page;
 984                         int off = sk->sk_sndmsg_off;
 985                         unsigned int left;
 986
 987                         if (page && (left = PAGE_SIZE - off) > 0) {
 988                                 if (copy >= left)
 989                                         copy = left;
 990                                 if (page != frag->page) {
 991                                         if (i == MAX_SKB_FRAGS) {
 992                                                 err = -EMSGSIZE;
 993                                                 goto error;
 994                                         }
 995                                         get_page(page);
 996                                         skb_fill_page_desc(skb, i, page, sk->sk_sndmsg_off, 0);
 997                                         frag = &skb_shinfo(skb)->frags[i];
 998                                 }
 999                         } else if (i < MAX_SKB_FRAGS) {
1000                                 if (copy > PAGE_SIZE)
1001                                         copy = PAGE_SIZE;
1002                                 page = alloc_pages(sk->sk_allocation, 0);
1003                                 if (page == NULL)  {
1004                                         err = -ENOMEM;
1005                                         goto error;
1006                                 }
1007                                 sk->sk_sndmsg_page = page;
1008                                 sk->sk_sndmsg_off = 0;
1009
1010                                 skb_fill_page_desc(skb, i, page, 0, 0);
1011                                 frag = &skb_shinfo(skb)->frags[i];
1012                                 skb->truesize += PAGE_SIZE;
1013                                 atomic_add(PAGE_SIZE, &sk->sk_wmem_alloc);
1014                         } else {
1015                                 err = -EMSGSIZE;
1016                                 goto error;
1017                         }
1018                         if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1019                                 err = -EFAULT;
1020                                 goto error;
1021                         }
1022                         sk->sk_sndmsg_off += copy;
1023                         frag->size += copy;
1024                         skb->len += copy;
1025                         skb->data_len += copy;
1026                 }
1027                 offset += copy;
1028                 length -= copy;
1029         }
1030
1031         return 0;
1032
1033 error:
1034         inet->cork.length -= length;
1035         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1036         return err;
1037 }
1038
1039 ssize_t ip_append_page(struct sock *sk, struct page *page,
1040                        int offset, size_t size, int flags)
1041 {
1042         struct inet_sock *inet = inet_sk(sk);
1043         struct sk_buff *skb;
1044         struct rtable *rt;
1045         struct ip_options *opt = NULL;
1046         int hh_len;
1047         int mtu;
1048         int len;
1049         int err;
1050         unsigned int maxfraglen, fragheaderlen, fraggap;
1051
1052         if (inet->hdrincl)
1053                 return -EPERM;
1054
1055         if (flags&MSG_PROBE)
1056                 return 0;
1057
1058         if (skb_queue_empty(&sk->sk_write_queue))
1059                 return -EINVAL;
1060
1061         rt = inet->cork.rt;
1062         if (inet->cork.flags & IPCORK_OPT)
1063                 opt = inet->cork.opt;
1064
1065         if (!(rt->u.dst.dev->features&NETIF_F_SG))
1066                 return -EOPNOTSUPP;
1067
1068         hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
1069         mtu = inet->cork.fragsize;
1070
1071         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1072         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1073
1074         if (inet->cork.length + size > 0xFFFF - fragheaderlen) {
1075                 ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
1076                 return -EMSGSIZE;
1077         }
1078
1079         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1080                 return -EINVAL;
1081
1082         inet->cork.length += size;
1083         if ((sk->sk_protocol == IPPROTO_UDP) &&
1084             (rt->u.dst.dev->features & NETIF_F_UFO)) {
1085                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1086                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1087         }
1088
1089
1090         while (size > 0) {
1091                 int i;
1092
1093                 if (skb_is_gso(skb))
1094                         len = size;
1095                 else {
1096
1097                         /* Check if the remaining data fits into current packet. */
1098                         len = mtu - skb->len;
1099                         if (len < size)
1100                                 len = maxfraglen - skb->len;
1101                 }
1102                 if (len <= 0) {
1103                         struct sk_buff *skb_prev;
1104                         char *data;
1105                         struct iphdr *iph;
1106                         int alloclen;
1107
1108                         skb_prev = skb;
1109                         fraggap = skb_prev->len - maxfraglen;
1110
1111                         alloclen = fragheaderlen + hh_len + fraggap + 15;
1112                         skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1113                         if (unlikely(!skb)) {
1114                                 err = -ENOBUFS;
1115                                 goto error;
1116                         }
1117
1118                         /*
1119                          *      Fill in the control structures
1120                          */
1121                         skb->ip_summed = CHECKSUM_NONE;
1122                         skb->csum = 0;
1123                         skb_reserve(skb, hh_len);
1124
1125                         /*
1126                          *      Find where to start putting bytes.
1127                          */
1128                         data = skb_put(skb, fragheaderlen + fraggap);
1129                         skb->nh.iph = iph = (struct iphdr *)data;
1130                         data += fragheaderlen;
1131                         skb->h.raw = data;
1132
1133                         if (fraggap) {
1134                                 skb->csum = skb_copy_and_csum_bits(
1135                                         skb_prev, maxfraglen,
1136                                         data, fraggap, 0);
1137                                 skb_prev->csum = csum_sub(skb_prev->csum,
1138                                                           skb->csum);
1139                                 pskb_trim_unique(skb_prev, maxfraglen);
1140                         }
1141
1142                         /*
1143                          * Put the packet on the pending queue.
1144                          */
1145                         __skb_queue_tail(&sk->sk_write_queue, skb);
1146                         continue;
1147                 }
1148
1149                 i = skb_shinfo(skb)->nr_frags;
1150                 if (len > size)
1151                         len = size;
1152                 if (skb_can_coalesce(skb, i, page, offset)) {
1153                         skb_shinfo(skb)->frags[i-1].size += len;
1154                 } else if (i < MAX_SKB_FRAGS) {
1155                         get_page(page);
1156                         skb_fill_page_desc(skb, i, page, offset, len);
1157                 } else {
1158                         err = -EMSGSIZE;
1159                         goto error;
1160                 }
1161
1162                 if (skb->ip_summed == CHECKSUM_NONE) {
1163                         __wsum csum;
1164                         csum = csum_page(page, offset, len);
1165                         skb->csum = csum_block_add(skb->csum, csum, skb->len);
1166                 }
1167
1168                 skb->len += len;
1169                 skb->data_len += len;
1170                 offset += len;
1171                 size -= len;
1172         }
1173         return 0;
1174
1175 error:
1176         inet->cork.length -= size;
1177         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1178         return err;
1179 }
1180
1181 /*
1182  *      Combined all pending IP fragments on the socket as one IP datagram
1183  *      and push them out.
1184  */
1185 int ip_push_pending_frames(struct sock *sk)
1186 {
1187         struct sk_buff *skb, *tmp_skb;
1188         struct sk_buff **tail_skb;
1189         struct inet_sock *inet = inet_sk(sk);
1190         struct ip_options *opt = NULL;
1191         struct rtable *rt = inet->cork.rt;
1192         struct iphdr *iph;
1193         __be16 df = 0;
1194         __u8 ttl;
1195         int err = 0;
1196
1197         if ((skb = __skb_dequeue(&sk->sk_write_queue)) == NULL)
1198                 goto out;
1199         tail_skb = &(skb_shinfo(skb)->frag_list);
1200
1201         /* move skb->data to ip header from ext header */
1202         if (skb->data < skb->nh.raw)
1203                 __skb_pull(skb, skb->nh.raw - skb->data);
1204         while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
1205                 __skb_pull(tmp_skb, skb->h.raw - skb->nh.raw);
1206                 *tail_skb = tmp_skb;
1207                 tail_skb = &(tmp_skb->next);
1208                 skb->len += tmp_skb->len;
1209                 skb->data_len += tmp_skb->len;
1210                 skb->truesize += tmp_skb->truesize;
1211                 __sock_put(tmp_skb->sk);
1212                 tmp_skb->destructor = NULL;
1213                 tmp_skb->sk = NULL;
1214         }
1215
1216         /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1217          * to fragment the frame generated here. No matter, what transforms
1218          * how transforms change size of the packet, it will come out.
1219          */
1220         if (inet->pmtudisc != IP_PMTUDISC_DO)
1221                 skb->local_df = 1;
1222
1223         /* DF bit is set when we want to see DF on outgoing frames.
1224          * If local_df is set too, we still allow to fragment this frame
1225          * locally. */
1226         if (inet->pmtudisc == IP_PMTUDISC_DO ||
1227             (skb->len <= dst_mtu(&rt->u.dst) &&
1228              ip_dont_fragment(sk, &rt->u.dst)))
1229                 df = htons(IP_DF);
1230
1231         if (inet->cork.flags & IPCORK_OPT)
1232                 opt = inet->cork.opt;
1233
1234         if (rt->rt_type == RTN_MULTICAST)
1235                 ttl = inet->mc_ttl;
1236         else
1237                 ttl = ip_select_ttl(inet, &rt->u.dst);
1238
1239         iph = (struct iphdr *)skb->data;
1240         iph->version = 4;
1241         iph->ihl = 5;
1242         if (opt) {
1243                 iph->ihl += opt->optlen>>2;
1244                 ip_options_build(skb, opt, inet->cork.addr, rt, 0);
1245         }
1246         iph->tos = inet->tos;
1247         iph->tot_len = htons(skb->len);
1248         iph->frag_off = df;
1249         ip_select_ident(iph, &rt->u.dst, sk);
1250         iph->ttl = ttl;
1251         iph->protocol = sk->sk_protocol;
1252         iph->saddr = rt->rt_src;
1253         iph->daddr = rt->rt_dst;
1254         ip_send_check(iph);
1255
1256         skb->priority = sk->sk_priority;
1257         skb->dst = dst_clone(&rt->u.dst);
1258
1259         /* Netfilter gets whole the not fragmented skb. */
1260         err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
1261                       skb->dst->dev, dst_output);
1262         if (err) {
1263                 if (err > 0)
1264                         err = inet->recverr ? net_xmit_errno(err) : 0;
1265                 if (err)
1266                         goto error;
1267         }
1268
1269 out:
1270         inet->cork.flags &= ~IPCORK_OPT;
1271         kfree(inet->cork.opt);
1272         inet->cork.opt = NULL;
1273         if (inet->cork.rt) {
1274                 ip_rt_put(inet->cork.rt);
1275                 inet->cork.rt = NULL;
1276         }
1277         return err;
1278
1279 error:
1280         IP_INC_STATS(IPSTATS_MIB_OUTDISCARDS);
1281         goto out;
1282 }
1283
1284 /*
1285  *      Throw away all pending data on the socket.
1286  */
1287 void ip_flush_pending_frames(struct sock *sk)
1288 {
1289         struct inet_sock *inet = inet_sk(sk);
1290         struct sk_buff *skb;
1291
1292         while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
1293                 kfree_skb(skb);
1294
1295         inet->cork.flags &= ~IPCORK_OPT;
1296         kfree(inet->cork.opt);
1297         inet->cork.opt = NULL;
1298         if (inet->cork.rt) {
1299                 ip_rt_put(inet->cork.rt);
1300                 inet->cork.rt = NULL;
1301         }
1302 }
1303
1304
1305 /*
1306  *      Fetch data from kernel space and fill in checksum if needed.
1307  */
1308 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1309                               int len, int odd, struct sk_buff *skb)
1310 {
1311         __wsum csum;
1312
1313         csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1314         skb->csum = csum_block_add(skb->csum, csum, odd);
1315         return 0;
1316 }
1317
1318 /*
1319  *      Generic function to send a packet as reply to another packet.
1320  *      Used to send TCP resets so far. ICMP should use this function too.
1321  *
1322  *      Should run single threaded per socket because it uses the sock
1323  *      structure to pass arguments.
1324  *
1325  *      LATER: switch from ip_build_xmit to ip_append_*
1326  */
1327 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
1328                    unsigned int len)
1329 {
1330         struct inet_sock *inet = inet_sk(sk);
1331         struct {
1332                 struct ip_options       opt;
1333                 char                    data[40];
1334         } replyopts;
1335         struct ipcm_cookie ipc;
1336         __be32 daddr;
1337         struct rtable *rt = (struct rtable*)skb->dst;
1338
1339         if (ip_options_echo(&replyopts.opt, skb))
1340                 return;
1341
1342         daddr = ipc.addr = rt->rt_src;
1343         ipc.opt = NULL;
1344
1345         if (replyopts.opt.optlen) {
1346                 ipc.opt = &replyopts.opt;
1347
1348                 if (ipc.opt->srr)
1349                         daddr = replyopts.opt.faddr;
1350         }
1351
1352         {
1353                 struct flowi fl = { .nl_u = { .ip4_u =
1354                                               { .daddr = daddr,
1355                                                 .saddr = rt->rt_spec_dst,
1356                                                 .tos = RT_TOS(skb->nh.iph->tos) } },
1357                                     /* Not quite clean, but right. */
1358                                     .uli_u = { .ports =
1359                                                { .sport = skb->h.th->dest,
1360                                                  .dport = skb->h.th->source } },
1361                                     .proto = sk->sk_protocol };
1362                 security_skb_classify_flow(skb, &fl);
1363                 if (ip_route_output_key(&rt, &fl))
1364                         return;
1365         }
1366
1367         /* And let IP do all the hard work.
1368
1369            This chunk is not reenterable, hence spinlock.
1370            Note that it uses the fact, that this function is called
1371            with locally disabled BH and that sk cannot be already spinlocked.
1372          */
1373         bh_lock_sock(sk);
1374         inet->tos = skb->nh.iph->tos;
1375         sk->sk_priority = skb->priority;
1376         sk->sk_protocol = skb->nh.iph->protocol;
1377         ip_append_data(sk, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1378                        &ipc, rt, MSG_DONTWAIT);
1379         if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1380                 if (arg->csumoffset >= 0)
1381                         *((__sum16 *)skb->h.raw + arg->csumoffset) = csum_fold(csum_add(skb->csum, arg->csum));
1382                 skb->ip_summed = CHECKSUM_NONE;
1383                 ip_push_pending_frames(sk);
1384         }
1385
1386         bh_unlock_sock(sk);
1387
1388         ip_rt_put(rt);
1389 }
1390
1391 void __init ip_init(void)
1392 {
1393         ip_rt_init();
1394         inet_initpeers();
1395
1396 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1397         igmp_mc_proc_init();
1398 #endif
1399 }
1400
1401 EXPORT_SYMBOL(ip_generic_getfrag);
1402 EXPORT_SYMBOL(ip_queue_xmit);
1403 EXPORT_SYMBOL(ip_send_check);