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  * Authors:     Ross Biro
   9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10  *              Donald Becker, <becker@super.org>
  11  *              Alan Cox, <Alan.Cox@linux.org>
  12  *              Richard Underwood
  13  *              Stefan Becker, <stefanb@yello.ping.de>
  14  *              Jorge Cwik, <jorge@laser.satlink.net>
  15  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  16  *              Hirokazu Takahashi, <taka@valinux.co.jp>
  17  *
  18  *      See ip_input.c for original log
  19  *
  20  *      Fixes:
  21  *              Alan Cox        :       Missing nonblock feature in ip_build_xmit.
  22  *              Mike Kilburn    :       htons() missing in ip_build_xmit.
  23  *              Bradford Johnson:       Fix faulty handling of some frames when
  24  *                                      no route is found.
  25  *              Alexander Demenshin:    Missing sk/skb free in ip_queue_xmit
  26  *                                      (in case if packet not accepted by
  27  *                                      output firewall rules)
  28  *              Mike McLagan    :       Routing by source
  29  *              Alexey Kuznetsov:       use new route cache
  30  *              Andi Kleen:             Fix broken PMTU recovery and remove
  31  *                                      some redundant tests.
  32  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  33  *              Andi Kleen      :       Replace ip_reply with ip_send_reply.
  34  *              Andi Kleen      :       Split fast and slow ip_build_xmit path
  35  *                                      for decreased register pressure on x86
  36  *                                      and more readibility.
  37  *              Marc Boucher    :       When call_out_firewall returns FW_QUEUE,
  38  *                                      silently drop skb instead of failing with -EPERM.
  39  *              Detlev Wengorz  :       Copy protocol for fragments.
  40  *              Hirokazu Takahashi:     HW checksumming for outgoing UDP
  41  *                                      datagrams.
  42  *              Hirokazu Takahashi:     sendfile() on UDP works now.
  43  */
  44
  45 #include <asm/uaccess.h>
  46 #include <asm/system.h>
  47 #include <linux/module.h>
  48 #include <linux/types.h>
  49 #include <linux/kernel.h>
  50 #include <linux/mm.h>
  51 #include <linux/string.h>
  52 #include <linux/errno.h>
  53 #include <linux/highmem.h>
  54 #include <linux/slab.h>
  55
  56 #include <linux/socket.h>
  57 #include <linux/sockios.h>
  58 #include <linux/in.h>
  59 #include <linux/inet.h>
  60 #include <linux/netdevice.h>
  61 #include <linux/etherdevice.h>
  62 #include <linux/proc_fs.h>
  63 #include <linux/stat.h>
  64 #include <linux/init.h>
  65
  66 #include <net/snmp.h>
  67 #include <net/ip.h>
  68 #include <net/protocol.h>
  69 #include <net/route.h>
  70 #include <net/xfrm.h>
  71 #include <linux/skbuff.h>
  72 #include <net/sock.h>
  73 #include <net/arp.h>
  74 #include <net/icmp.h>
  75 #include <net/checksum.h>
  76 #include <net/inetpeer.h>
  77 #include <linux/igmp.h>
  78 #include <linux/netfilter_ipv4.h>
  79 #include <linux/netfilter_bridge.h>
  80 #include <linux/mroute.h>
  81 #include <linux/netlink.h>
  82 #include <linux/tcp.h>
  83
  84 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
  85 EXPORT_SYMBOL(sysctl_ip_default_ttl);
  86
  87 /* Generate a checksum for an outgoing IP datagram. */
  88 __inline__ void ip_send_check(struct iphdr *iph)
  89 {
  90         iph->check = 0;
  91         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  92 }
  93 EXPORT_SYMBOL(ip_send_check);
  94
  95 int __ip_local_out(struct sk_buff *skb)
  96 {
  97         struct iphdr *iph = ip_hdr(skb);
  98
  99         iph->tot_len = htons(skb->len);
 100         ip_send_check(iph);
 101         return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
 102                        skb_dst(skb)->dev, dst_output);
 103 }
 104
 105 int ip_local_out(struct sk_buff *skb)
 106 {
 107         int err;
 108
 109         err = __ip_local_out(skb);
 110         if (likely(err == 1))
 111                 err = dst_output(skb);
 112
 113         return err;
 114 }
 115 EXPORT_SYMBOL_GPL(ip_local_out);
 116
 117 /* dev_loopback_xmit for use with netfilter. */
 118 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
 119 {
 120         skb_reset_mac_header(newskb);
 121         __skb_pull(newskb, skb_network_offset(newskb));
 122         newskb->pkt_type = PACKET_LOOPBACK;
 123         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 124         WARN_ON(!skb_dst(newskb));
 125         skb_dst_force(newskb);
 126         netif_rx_ni(newskb);
 127         return 0;
 128 }
 129
 130 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 131 {
 132         int ttl = inet->uc_ttl;
 133
 134         if (ttl < 0)
 135                 ttl = ip4_dst_hoplimit(dst);
 136         return ttl;
 137 }
 138
 139 /*
 140  *              Add an ip header to a skbuff and send it out.
 141  *
 142  */
 143 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 144                           __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 145 {
 146         struct inet_sock *inet = inet_sk(sk);
 147         struct rtable *rt = skb_rtable(skb);
 148         struct iphdr *iph;
 149
 150         /* Build the IP header. */
 151         skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 152         skb_reset_network_header(skb);
 153         iph = ip_hdr(skb);
 154         iph->version  = 4;
 155         iph->ihl      = 5;
 156         iph->tos      = inet->tos;
 157         if (ip_dont_fragment(sk, &rt->dst))
 158                 iph->frag_off = htons(IP_DF);
 159         else
 160                 iph->frag_off = 0;
 161         iph->ttl      = ip_select_ttl(inet, &rt->dst);
 162         iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 163         iph->saddr    = saddr;
 164         iph->protocol = sk->sk_protocol;
 165         ip_select_ident(iph, &rt->dst, sk);
 166
 167         if (opt && opt->opt.optlen) {
 168                 iph->ihl += opt->opt.optlen>>2;
 169                 ip_options_build(skb, &opt->opt, daddr, rt, 0);
 170         }
 171
 172         skb->priority = sk->sk_priority;
 173         skb->mark = sk->sk_mark;
 174
 175         /* Send it out. */
 176         return ip_local_out(skb);
 177 }
 178 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 179
 180 static inline int ip_finish_output2(struct sk_buff *skb)
 181 {
 182         struct dst_entry *dst = skb_dst(skb);
 183         struct rtable *rt = (struct rtable *)dst;
 184         struct net_device *dev = dst->dev;
 185         unsigned int hh_len = LL_RESERVED_SPACE(dev);
 186         struct neighbour *neigh;
 187
 188         if (rt->rt_type == RTN_MULTICAST) {
 189                 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
 190         } else if (rt->rt_type == RTN_BROADCAST)
 191                 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
 192
 193         /* Be paranoid, rather than too clever. */
 194         if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 195                 struct sk_buff *skb2;
 196
 197                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 198                 if (skb2 == NULL) {
 199                         kfree_skb(skb);
 200                         return -ENOMEM;
 201                 }
 202                 if (skb->sk)
 203                         skb_set_owner_w(skb2, skb->sk);
 204                 kfree_skb(skb);
 205                 skb = skb2;
 206         }
 207
 208         rcu_read_lock();
 209         neigh = dst_get_neighbour(dst);
 210         if (neigh) {
 211                 int res = neigh_output(neigh, skb);
 212
 213                 rcu_read_unlock();
 214                 return res;
 215         }
 216         rcu_read_unlock();
 217
 218         if (net_ratelimit())
 219                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 220         kfree_skb(skb);
 221         return -EINVAL;
 222 }
 223
 224 static inline int ip_skb_dst_mtu(struct sk_buff *skb)
 225 {
 226         struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
 227
 228         return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
 229                skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
 230 }
 231
 232 static int ip_finish_output(struct sk_buff *skb)
 233 {
 234 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 235         /* Policy lookup after SNAT yielded a new policy */
 236         if (skb_dst(skb)->xfrm != NULL) {
 237                 IPCB(skb)->flags |= IPSKB_REROUTED;
 238                 return dst_output(skb);
 239         }
 240 #endif
 241         if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
 242                 return ip_fragment(skb, ip_finish_output2);
 243         else
 244                 return ip_finish_output2(skb);
 245 }
 246
 247 int ip_mc_output(struct sk_buff *skb)
 248 {
 249         struct sock *sk = skb->sk;
 250         struct rtable *rt = skb_rtable(skb);
 251         struct net_device *dev = rt->dst.dev;
 252
 253         /*
 254          *      If the indicated interface is up and running, send the packet.
 255          */
 256         IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 257
 258         skb->dev = dev;
 259         skb->protocol = htons(ETH_P_IP);
 260
 261         /*
 262          *      Multicasts are looped back for other local users
 263          */
 264
 265         if (rt->rt_flags&RTCF_MULTICAST) {
 266                 if (sk_mc_loop(sk)
 267 #ifdef CONFIG_IP_MROUTE
 268                 /* Small optimization: do not loopback not local frames,
 269                    which returned after forwarding; they will be  dropped
 270                    by ip_mr_input in any case.
 271                    Note, that local frames are looped back to be delivered
 272                    to local recipients.
 273
 274                    This check is duplicated in ip_mr_input at the moment.
 275                  */
 276                     &&
 277                     ((rt->rt_flags & RTCF_LOCAL) ||
 278                      !(IPCB(skb)->flags & IPSKB_FORWARDED))
 279 #endif
 280                    ) {
 281                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 282                         if (newskb)
 283                                 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 284                                         newskb, NULL, newskb->dev,
 285                                         ip_dev_loopback_xmit);
 286                 }
 287
 288                 /* Multicasts with ttl 0 must not go beyond the host */
 289
 290                 if (ip_hdr(skb)->ttl == 0) {
 291                         kfree_skb(skb);
 292                         return 0;
 293                 }
 294         }
 295
 296         if (rt->rt_flags&RTCF_BROADCAST) {
 297                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 298                 if (newskb)
 299                         NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
 300                                 NULL, newskb->dev, ip_dev_loopback_xmit);
 301         }
 302
 303         return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
 304                             skb->dev, ip_finish_output,
 305                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 306 }
 307
 308 int ip_output(struct sk_buff *skb)
 309 {
 310         struct net_device *dev = skb_dst(skb)->dev;
 311
 312         IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 313
 314         skb->dev = dev;
 315         skb->protocol = htons(ETH_P_IP);
 316
 317         return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
 318                             ip_finish_output,
 319                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 320 }
 321
 322 int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
 323 {
 324         struct sock *sk = skb->sk;
 325         struct inet_sock *inet = inet_sk(sk);
 326         struct ip_options_rcu *inet_opt;
 327         struct flowi4 *fl4;
 328         struct rtable *rt;
 329         struct iphdr *iph;
 330         int res;
 331
 332         /* Skip all of this if the packet is already routed,
 333          * f.e. by something like SCTP.
 334          */
 335         rcu_read_lock();
 336         inet_opt = rcu_dereference(inet->inet_opt);
 337         fl4 = &fl->u.ip4;
 338         rt = skb_rtable(skb);
 339         if (rt != NULL)
 340                 goto packet_routed;
 341
 342         /* Make sure we can route this packet. */
 343         rt = (struct rtable *)__sk_dst_check(sk, 0);
 344         if (rt == NULL) {
 345                 __be32 daddr;
 346
 347                 /* Use correct destination address if we have options. */
 348                 daddr = inet->inet_daddr;
 349                 if (inet_opt && inet_opt->opt.srr)
 350                         daddr = inet_opt->opt.faddr;
 351
 352                 /* If this fails, retransmit mechanism of transport layer will
 353                  * keep trying until route appears or the connection times
 354                  * itself out.
 355                  */
 356                 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 357                                            daddr, inet->inet_saddr,
 358                                            inet->inet_dport,
 359                                            inet->inet_sport,
 360                                            sk->sk_protocol,
 361                                            RT_CONN_FLAGS(sk),
 362                                            sk->sk_bound_dev_if);
 363                 if (IS_ERR(rt))
 364                         goto no_route;
 365                 sk_setup_caps(sk, &rt->dst);
 366         }
 367         skb_dst_set_noref(skb, &rt->dst);
 368
 369 packet_routed:
 370         if (inet_opt && inet_opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
 371                 goto no_route;
 372
 373         /* OK, we know where to send it, allocate and build IP header. */
 374         skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 375         skb_reset_network_header(skb);
 376         iph = ip_hdr(skb);
 377         *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 378         if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
 379                 iph->frag_off = htons(IP_DF);
 380         else
 381                 iph->frag_off = 0;
 382         iph->ttl      = ip_select_ttl(inet, &rt->dst);
 383         iph->protocol = sk->sk_protocol;
 384         iph->saddr    = fl4->saddr;
 385         iph->daddr    = fl4->daddr;
 386         /* Transport layer set skb->h.foo itself. */
 387
 388         if (inet_opt && inet_opt->opt.optlen) {
 389                 iph->ihl += inet_opt->opt.optlen >> 2;
 390                 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 391         }
 392
 393         ip_select_ident_more(iph, &rt->dst, sk,
 394                              (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 395
 396         skb->priority = sk->sk_priority;
 397         skb->mark = sk->sk_mark;
 398
 399         res = ip_local_out(skb);
 400         rcu_read_unlock();
 401         return res;
 402
 403 no_route:
 404         rcu_read_unlock();
 405         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 406         kfree_skb(skb);
 407         return -EHOSTUNREACH;
 408 }
 409 EXPORT_SYMBOL(ip_queue_xmit);
 410
 411
 412 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 413 {
 414         to->pkt_type = from->pkt_type;
 415         to->priority = from->priority;
 416         to->protocol = from->protocol;
 417         skb_dst_drop(to);
 418         skb_dst_copy(to, from);
 419         to->dev = from->dev;
 420         to->mark = from->mark;
 421
 422         /* Copy the flags to each fragment. */
 423         IPCB(to)->flags = IPCB(from)->flags;
 424
 425 #ifdef CONFIG_NET_SCHED
 426         to->tc_index = from->tc_index;
 427 #endif
 428         nf_copy(to, from);
 429 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
 430     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 431         to->nf_trace = from->nf_trace;
 432 #endif
 433 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 434         to->ipvs_property = from->ipvs_property;
 435 #endif
 436         skb_copy_secmark(to, from);
 437 }
 438
 439 /*
 440  *      This IP datagram is too large to be sent in one piece.  Break it up into
 441  *      smaller pieces (each of size equal to IP header plus
 442  *      a block of the data of the original IP data part) that will yet fit in a
 443  *      single device frame, and queue such a frame for sending.
 444  */
 445
 446 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 447 {
 448         struct iphdr *iph;
 449         int ptr;
 450         struct net_device *dev;
 451         struct sk_buff *skb2;
 452         unsigned int mtu, hlen, left, len, ll_rs;
 453         int offset;
 454         __be16 not_last_frag;
 455         struct rtable *rt = skb_rtable(skb);
 456         int err = 0;
 457
 458         dev = rt->dst.dev;
 459
 460         /*
 461          *      Point into the IP datagram header.
 462          */
 463
 464         iph = ip_hdr(skb);
 465
 466         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 467                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 468                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 469                           htonl(ip_skb_dst_mtu(skb)));
 470                 kfree_skb(skb);
 471                 return -EMSGSIZE;
 472         }
 473
 474         /*
 475          *      Setup starting values.
 476          */
 477
 478         hlen = iph->ihl * 4;
 479         mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
 480 #ifdef CONFIG_BRIDGE_NETFILTER
 481         if (skb->nf_bridge)
 482                 mtu -= nf_bridge_mtu_reduction(skb);
 483 #endif
 484         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 485
 486         /* When frag_list is given, use it. First, check its validity:
 487          * some transformers could create wrong frag_list or break existing
 488          * one, it is not prohibited. In this case fall back to copying.
 489          *
 490          * LATER: this step can be merged to real generation of fragments,
 491          * we can switch to copy when see the first bad fragment.
 492          */
 493         if (skb_has_frag_list(skb)) {
 494                 struct sk_buff *frag, *frag2;
 495                 int first_len = skb_pagelen(skb);
 496
 497                 if (first_len - hlen > mtu ||
 498                     ((first_len - hlen) & 7) ||
 499                     ip_is_fragment(iph) ||
 500                     skb_cloned(skb))
 501                         goto slow_path;
 502
 503                 skb_walk_frags(skb, frag) {
 504                         /* Correct geometry. */
 505                         if (frag->len > mtu ||
 506                             ((frag->len & 7) && frag->next) ||
 507                             skb_headroom(frag) < hlen)
 508                                 goto slow_path_clean;
 509
 510                         /* Partially cloned skb? */
 511                         if (skb_shared(frag))
 512                                 goto slow_path_clean;
 513
 514                         BUG_ON(frag->sk);
 515                         if (skb->sk) {
 516                                 frag->sk = skb->sk;
 517                                 frag->destructor = sock_wfree;
 518                         }
 519                         skb->truesize -= frag->truesize;
 520                 }
 521
 522                 /* Everything is OK. Generate! */
 523
 524                 err = 0;
 525                 offset = 0;
 526                 frag = skb_shinfo(skb)->frag_list;
 527                 skb_frag_list_init(skb);
 528                 skb->data_len = first_len - skb_headlen(skb);
 529                 skb->len = first_len;
 530                 iph->tot_len = htons(first_len);
 531                 iph->frag_off = htons(IP_MF);
 532                 ip_send_check(iph);
 533
 534                 for (;;) {
 535                         /* Prepare header of the next frame,
 536                          * before previous one went down. */
 537                         if (frag) {
 538                                 frag->ip_summed = CHECKSUM_NONE;
 539                                 skb_reset_transport_header(frag);
 540                                 __skb_push(frag, hlen);
 541                                 skb_reset_network_header(frag);
 542                                 memcpy(skb_network_header(frag), iph, hlen);
 543                                 iph = ip_hdr(frag);
 544                                 iph->tot_len = htons(frag->len);
 545                                 ip_copy_metadata(frag, skb);
 546                                 if (offset == 0)
 547                                         ip_options_fragment(frag);
 548                                 offset += skb->len - hlen;
 549                                 iph->frag_off = htons(offset>>3);
 550                                 if (frag->next != NULL)
 551                                         iph->frag_off |= htons(IP_MF);
 552                                 /* Ready, complete checksum */
 553                                 ip_send_check(iph);
 554                         }
 555
 556                         err = output(skb);
 557
 558                         if (!err)
 559                                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 560                         if (err || !frag)
 561                                 break;
 562
 563                         skb = frag;
 564                         frag = skb->next;
 565                         skb->next = NULL;
 566                 }
 567
 568                 if (err == 0) {
 569                         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 570                         return 0;
 571                 }
 572
 573                 while (frag) {
 574                         skb = frag->next;
 575                         kfree_skb(frag);
 576                         frag = skb;
 577                 }
 578                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 579                 return err;
 580
 581 slow_path_clean:
 582                 skb_walk_frags(skb, frag2) {
 583                         if (frag2 == frag)
 584                                 break;
 585                         frag2->sk = NULL;
 586                         frag2->destructor = NULL;
 587                         skb->truesize += frag2->truesize;
 588                 }
 589         }
 590
 591 slow_path:
 592         left = skb->len - hlen;         /* Space per frame */
 593         ptr = hlen;             /* Where to start from */
 594
 595         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 596          * we need to make room for the encapsulating header
 597          */
 598         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
 599
 600         /*
 601          *      Fragment the datagram.
 602          */
 603
 604         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 605         not_last_frag = iph->frag_off & htons(IP_MF);
 606
 607         /*
 608          *      Keep copying data until we run out.
 609          */
 610
 611         while (left > 0) {
 612                 len = left;
 613                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 614                 if (len > mtu)
 615                         len = mtu;
 616                 /* IF: we are not sending up to and including the packet end
 617                    then align the next start on an eight byte boundary */
 618                 if (len < left) {
 619                         len &= ~7;
 620                 }
 621                 /*
 622                  *      Allocate buffer.
 623                  */
 624
 625                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 626                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 627                         err = -ENOMEM;
 628                         goto fail;
 629                 }
 630
 631                 /*
 632                  *      Set up data on packet
 633                  */
 634
 635                 ip_copy_metadata(skb2, skb);
 636                 skb_reserve(skb2, ll_rs);
 637                 skb_put(skb2, len + hlen);
 638                 skb_reset_network_header(skb2);
 639                 skb2->transport_header = skb2->network_header + hlen;
 640
 641                 /*
 642                  *      Charge the memory for the fragment to any owner
 643                  *      it might possess
 644                  */
 645
 646                 if (skb->sk)
 647                         skb_set_owner_w(skb2, skb->sk);
 648
 649                 /*
 650                  *      Copy the packet header into the new buffer.
 651                  */
 652
 653                 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
 654
 655                 /*
 656                  *      Copy a block of the IP datagram.
 657                  */
 658                 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
 659                         BUG();
 660                 left -= len;
 661
 662                 /*
 663                  *      Fill in the new header fields.
 664                  */
 665                 iph = ip_hdr(skb2);
 666                 iph->frag_off = htons((offset >> 3));
 667
 668                 /* ANK: dirty, but effective trick. Upgrade options only if
 669                  * the segment to be fragmented was THE FIRST (otherwise,
 670                  * options are already fixed) and make it ONCE
 671                  * on the initial skb, so that all the following fragments
 672                  * will inherit fixed options.
 673                  */
 674                 if (offset == 0)
 675                         ip_options_fragment(skb);
 676
 677                 /*
 678                  *      Added AC : If we are fragmenting a fragment that's not the
 679                  *                 last fragment then keep MF on each bit
 680                  */
 681                 if (left > 0 || not_last_frag)
 682                         iph->frag_off |= htons(IP_MF);
 683                 ptr += len;
 684                 offset += len;
 685
 686                 /*
 687                  *      Put this fragment into the sending queue.
 688                  */
 689                 iph->tot_len = htons(len + hlen);
 690
 691                 ip_send_check(iph);
 692
 693                 err = output(skb2);
 694                 if (err)
 695                         goto fail;
 696
 697                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 698         }
 699         kfree_skb(skb);
 700         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 701         return err;
 702
 703 fail:
 704         kfree_skb(skb);
 705         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 706         return err;
 707 }
 708 EXPORT_SYMBOL(ip_fragment);
 709
 710 int
 711 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 712 {
 713         struct iovec *iov = from;
 714
 715         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 716                 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 717                         return -EFAULT;
 718         } else {
 719                 __wsum csum = 0;
 720                 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 721                         return -EFAULT;
 722                 skb->csum = csum_block_add(skb->csum, csum, odd);
 723         }
 724         return 0;
 725 }
 726 EXPORT_SYMBOL(ip_generic_getfrag);
 727
 728 static inline __wsum
 729 csum_page(struct page *page, int offset, int copy)
 730 {
 731         char *kaddr;
 732         __wsum csum;
 733         kaddr = kmap(page);
 734         csum = csum_partial(kaddr + offset, copy, 0);
 735         kunmap(page);
 736         return csum;
 737 }
 738
 739 static inline int ip_ufo_append_data(struct sock *sk,
 740                         struct sk_buff_head *queue,
 741                         int getfrag(void *from, char *to, int offset, int len,
 742                                int odd, struct sk_buff *skb),
 743                         void *from, int length, int hh_len, int fragheaderlen,
 744                         int transhdrlen, int maxfraglen, unsigned int flags)
 745 {
 746         struct sk_buff *skb;
 747         int err;
 748
 749         /* There is support for UDP fragmentation offload by network
 750          * device, so create one single skb packet containing complete
 751          * udp datagram
 752          */
 753         if ((skb = skb_peek_tail(queue)) == NULL) {
 754                 skb = sock_alloc_send_skb(sk,
 755                         hh_len + fragheaderlen + transhdrlen + 20,
 756                         (flags & MSG_DONTWAIT), &err);
 757
 758                 if (skb == NULL)
 759                         return err;
 760
 761                 /* reserve space for Hardware header */
 762                 skb_reserve(skb, hh_len);
 763
 764                 /* create space for UDP/IP header */
 765                 skb_put(skb, fragheaderlen + transhdrlen);
 766
 767                 /* initialize network header pointer */
 768                 skb_reset_network_header(skb);
 769
 770                 /* initialize protocol header pointer */
 771                 skb->transport_header = skb->network_header + fragheaderlen;
 772
 773                 skb->ip_summed = CHECKSUM_PARTIAL;
 774                 skb->csum = 0;
 775
 776                 /* specify the length of each IP datagram fragment */
 777                 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
 778                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 779                 __skb_queue_tail(queue, skb);
 780         }
 781
 782         return skb_append_datato_frags(sk, skb, getfrag, from,
 783                                        (length - transhdrlen));
 784 }
 785
 786 static int __ip_append_data(struct sock *sk,
 787                             struct flowi4 *fl4,
 788                             struct sk_buff_head *queue,
 789                             struct inet_cork *cork,
 790                             int getfrag(void *from, char *to, int offset,
 791                                         int len, int odd, struct sk_buff *skb),
 792                             void *from, int length, int transhdrlen,
 793                             unsigned int flags)
 794 {
 795         struct inet_sock *inet = inet_sk(sk);
 796         struct sk_buff *skb;
 797
 798         struct ip_options *opt = cork->opt;
 799         int hh_len;
 800         int exthdrlen;
 801         int mtu;
 802         int copy;
 803         int err;
 804         int offset = 0;
 805         unsigned int maxfraglen, fragheaderlen;
 806         int csummode = CHECKSUM_NONE;
 807         struct rtable *rt = (struct rtable *)cork->dst;
 808
 809         skb = skb_peek_tail(queue);
 810
 811         exthdrlen = !skb ? rt->dst.header_len : 0;
 812         mtu = cork->fragsize;
 813
 814         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 815
 816         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 817         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 818
 819         if (cork->length + length > 0xFFFF - fragheaderlen) {
 820                 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 821                                mtu-exthdrlen);
 822                 return -EMSGSIZE;
 823         }
 824
 825         /*
 826          * transhdrlen > 0 means that this is the first fragment and we wish
 827          * it won't be fragmented in the future.
 828          */
 829         if (transhdrlen &&
 830             length + fragheaderlen <= mtu &&
 831             rt->dst.dev->features & NETIF_F_V4_CSUM &&
 832             !exthdrlen)
 833                 csummode = CHECKSUM_PARTIAL;
 834
 835         cork->length += length;
 836         if (((length > mtu) || (skb && skb_is_gso(skb))) &&
 837             (sk->sk_protocol == IPPROTO_UDP) &&
 838             (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
 839                 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 840                                          hh_len, fragheaderlen, transhdrlen,
 841                                          maxfraglen, flags);
 842                 if (err)
 843                         goto error;
 844                 return 0;
 845         }
 846
 847         /* So, what's going on in the loop below?
 848          *
 849          * We use calculated fragment length to generate chained skb,
 850          * each of segments is IP fragment ready for sending to network after
 851          * adding appropriate IP header.
 852          */
 853
 854         if (!skb)
 855                 goto alloc_new_skb;
 856
 857         while (length > 0) {
 858                 /* Check if the remaining data fits into current packet. */
 859                 copy = mtu - skb->len;
 860                 if (copy < length)
 861                         copy = maxfraglen - skb->len;
 862                 if (copy <= 0) {
 863                         char *data;
 864                         unsigned int datalen;
 865                         unsigned int fraglen;
 866                         unsigned int fraggap;
 867                         unsigned int alloclen;
 868                         struct sk_buff *skb_prev;
 869 alloc_new_skb:
 870                         skb_prev = skb;
 871                         if (skb_prev)
 872                                 fraggap = skb_prev->len - maxfraglen;
 873                         else
 874                                 fraggap = 0;
 875
 876                         /*
 877                          * If remaining data exceeds the mtu,
 878                          * we know we need more fragment(s).
 879                          */
 880                         datalen = length + fraggap;
 881                         if (datalen > mtu - fragheaderlen)
 882                                 datalen = maxfraglen - fragheaderlen;
 883                         fraglen = datalen + fragheaderlen;
 884
 885                         if ((flags & MSG_MORE) &&
 886                             !(rt->dst.dev->features&NETIF_F_SG))
 887                                 alloclen = mtu;
 888                         else
 889                                 alloclen = fraglen;
 890
 891                         alloclen += exthdrlen;
 892
 893                         /* The last fragment gets additional space at tail.
 894                          * Note, with MSG_MORE we overallocate on fragments,
 895                          * because we have no idea what fragment will be
 896                          * the last.
 897                          */
 898                         if (datalen == length + fraggap)
 899                                 alloclen += rt->dst.trailer_len;
 900
 901                         if (transhdrlen) {
 902                                 skb = sock_alloc_send_skb(sk,
 903                                                 alloclen + hh_len + 15,
 904                                                 (flags & MSG_DONTWAIT), &err);
 905                         } else {
 906                                 skb = NULL;
 907                                 if (atomic_read(&sk->sk_wmem_alloc) <=
 908                                     2 * sk->sk_sndbuf)
 909                                         skb = sock_wmalloc(sk,
 910                                                            alloclen + hh_len + 15, 1,
 911                                                            sk->sk_allocation);
 912                                 if (unlikely(skb == NULL))
 913                                         err = -ENOBUFS;
 914                                 else
 915                                         /* only the initial fragment is
 916                                            time stamped */
 917                                         cork->tx_flags = 0;
 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                         skb_shinfo(skb)->tx_flags = cork->tx_flags;
 929
 930                         /*
 931                          *      Find where to start putting bytes.
 932                          */
 933                         data = skb_put(skb, fraglen + exthdrlen);
 934                         skb_set_network_header(skb, exthdrlen);
 935                         skb->transport_header = (skb->network_header +
 936                                                  fragheaderlen);
 937                         data += fragheaderlen + exthdrlen;
 938
 939                         if (fraggap) {
 940                                 skb->csum = skb_copy_and_csum_bits(
 941                                         skb_prev, maxfraglen,
 942                                         data + transhdrlen, fraggap, 0);
 943                                 skb_prev->csum = csum_sub(skb_prev->csum,
 944                                                           skb->csum);
 945                                 data += fraggap;
 946                                 pskb_trim_unique(skb_prev, maxfraglen);
 947                         }
 948
 949                         copy = datalen - transhdrlen - fraggap;
 950                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 951                                 err = -EFAULT;
 952                                 kfree_skb(skb);
 953                                 goto error;
 954                         }
 955
 956                         offset += copy;
 957                         length -= datalen - fraggap;
 958                         transhdrlen = 0;
 959                         exthdrlen = 0;
 960                         csummode = CHECKSUM_NONE;
 961
 962                         /*
 963                          * Put the packet on the pending queue.
 964                          */
 965                         __skb_queue_tail(queue, skb);
 966                         continue;
 967                 }
 968
 969                 if (copy > length)
 970                         copy = length;
 971
 972                 if (!(rt->dst.dev->features&NETIF_F_SG)) {
 973                         unsigned int off;
 974
 975                         off = skb->len;
 976                         if (getfrag(from, skb_put(skb, copy),
 977                                         offset, copy, off, skb) < 0) {
 978                                 __skb_trim(skb, off);
 979                                 err = -EFAULT;
 980                                 goto error;
 981                         }
 982                 } else {
 983                         int i = skb_shinfo(skb)->nr_frags;
 984                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
 985                         struct page *page = cork->page;
 986                         int off = cork->off;
 987                         unsigned int left;
 988
 989                         if (page && (left = PAGE_SIZE - off) > 0) {
 990                                 if (copy >= left)
 991                                         copy = left;
 992                                 if (page != frag->page) {
 993                                         if (i == MAX_SKB_FRAGS) {
 994                                                 err = -EMSGSIZE;
 995                                                 goto error;
 996                                         }
 997                                         get_page(page);
 998                                         skb_fill_page_desc(skb, i, page, off, 0);
 999                                         frag = &skb_shinfo(skb)->frags[i];
1000                                 }
1001                         } else if (i < MAX_SKB_FRAGS) {
1002                                 if (copy > PAGE_SIZE)
1003                                         copy = PAGE_SIZE;
1004                                 page = alloc_pages(sk->sk_allocation, 0);
1005                                 if (page == NULL)  {
1006                                         err = -ENOMEM;
1007                                         goto error;
1008                                 }
1009                                 cork->page = page;
1010                                 cork->off = 0;
1011
1012                                 skb_fill_page_desc(skb, i, page, 0, 0);
1013                                 frag = &skb_shinfo(skb)->frags[i];
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                         cork->off += copy;
1023                         frag->size += copy;
1024                         skb->len += copy;
1025                         skb->data_len += copy;
1026                         skb->truesize += copy;
1027                         atomic_add(copy, &sk->sk_wmem_alloc);
1028                 }
1029                 offset += copy;
1030                 length -= copy;
1031         }
1032
1033         return 0;
1034
1035 error:
1036         cork->length -= length;
1037         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1038         return err;
1039 }
1040
1041 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1042                          struct ipcm_cookie *ipc, struct rtable **rtp)
1043 {
1044         struct inet_sock *inet = inet_sk(sk);
1045         struct ip_options_rcu *opt;
1046         struct rtable *rt;
1047
1048         /*
1049          * setup for corking.
1050          */
1051         opt = ipc->opt;
1052         if (opt) {
1053                 if (cork->opt == NULL) {
1054                         cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1055                                             sk->sk_allocation);
1056                         if (unlikely(cork->opt == NULL))
1057                                 return -ENOBUFS;
1058                 }
1059                 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1060                 cork->flags |= IPCORK_OPT;
1061                 cork->addr = ipc->addr;
1062         }
1063         rt = *rtp;
1064         if (unlikely(!rt))
1065                 return -EFAULT;
1066         /*
1067          * We steal reference to this route, caller should not release it
1068          */
1069         *rtp = NULL;
1070         cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1071                          rt->dst.dev->mtu : dst_mtu(&rt->dst);
1072         cork->dst = &rt->dst;
1073         cork->length = 0;
1074         cork->tx_flags = ipc->tx_flags;
1075         cork->page = NULL;
1076         cork->off = 0;
1077
1078         return 0;
1079 }
1080
1081 /*
1082  *      ip_append_data() and ip_append_page() can make one large IP datagram
1083  *      from many pieces of data. Each pieces will be holded on the socket
1084  *      until ip_push_pending_frames() is called. Each piece can be a page
1085  *      or non-page data.
1086  *
1087  *      Not only UDP, other transport protocols - e.g. raw sockets - can use
1088  *      this interface potentially.
1089  *
1090  *      LATER: length must be adjusted by pad at tail, when it is required.
1091  */
1092 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1093                    int getfrag(void *from, char *to, int offset, int len,
1094                                int odd, struct sk_buff *skb),
1095                    void *from, int length, int transhdrlen,
1096                    struct ipcm_cookie *ipc, struct rtable **rtp,
1097                    unsigned int flags)
1098 {
1099         struct inet_sock *inet = inet_sk(sk);
1100         int err;
1101
1102         if (flags&MSG_PROBE)
1103                 return 0;
1104
1105         if (skb_queue_empty(&sk->sk_write_queue)) {
1106                 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1107                 if (err)
1108                         return err;
1109         } else {
1110                 transhdrlen = 0;
1111         }
1112
1113         return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag,
1114                                 from, length, transhdrlen, flags);
1115 }
1116
1117 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1118                        int offset, size_t size, int flags)
1119 {
1120         struct inet_sock *inet = inet_sk(sk);
1121         struct sk_buff *skb;
1122         struct rtable *rt;
1123         struct ip_options *opt = NULL;
1124         struct inet_cork *cork;
1125         int hh_len;
1126         int mtu;
1127         int len;
1128         int err;
1129         unsigned int maxfraglen, fragheaderlen, fraggap;
1130
1131         if (inet->hdrincl)
1132                 return -EPERM;
1133
1134         if (flags&MSG_PROBE)
1135                 return 0;
1136
1137         if (skb_queue_empty(&sk->sk_write_queue))
1138                 return -EINVAL;
1139
1140         cork = &inet->cork.base;
1141         rt = (struct rtable *)cork->dst;
1142         if (cork->flags & IPCORK_OPT)
1143                 opt = cork->opt;
1144
1145         if (!(rt->dst.dev->features&NETIF_F_SG))
1146                 return -EOPNOTSUPP;
1147
1148         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1149         mtu = cork->fragsize;
1150
1151         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1152         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1153
1154         if (cork->length + size > 0xFFFF - fragheaderlen) {
1155                 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
1156                 return -EMSGSIZE;
1157         }
1158
1159         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1160                 return -EINVAL;
1161
1162         cork->length += size;
1163         if ((size + skb->len > mtu) &&
1164             (sk->sk_protocol == IPPROTO_UDP) &&
1165             (rt->dst.dev->features & NETIF_F_UFO)) {
1166                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1167                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1168         }
1169
1170
1171         while (size > 0) {
1172                 int i;
1173
1174                 if (skb_is_gso(skb))
1175                         len = size;
1176                 else {
1177
1178                         /* Check if the remaining data fits into current packet. */
1179                         len = mtu - skb->len;
1180                         if (len < size)
1181                                 len = maxfraglen - skb->len;
1182                 }
1183                 if (len <= 0) {
1184                         struct sk_buff *skb_prev;
1185                         int alloclen;
1186
1187                         skb_prev = skb;
1188                         fraggap = skb_prev->len - maxfraglen;
1189
1190                         alloclen = fragheaderlen + hh_len + fraggap + 15;
1191                         skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1192                         if (unlikely(!skb)) {
1193                                 err = -ENOBUFS;
1194                                 goto error;
1195                         }
1196
1197                         /*
1198                          *      Fill in the control structures
1199                          */
1200                         skb->ip_summed = CHECKSUM_NONE;
1201                         skb->csum = 0;
1202                         skb_reserve(skb, hh_len);
1203
1204                         /*
1205                          *      Find where to start putting bytes.
1206                          */
1207                         skb_put(skb, fragheaderlen + fraggap);
1208                         skb_reset_network_header(skb);
1209                         skb->transport_header = (skb->network_header +
1210                                                  fragheaderlen);
1211                         if (fraggap) {
1212                                 skb->csum = skb_copy_and_csum_bits(skb_prev,
1213                                                                    maxfraglen,
1214                                                     skb_transport_header(skb),
1215                                                                    fraggap, 0);
1216                                 skb_prev->csum = csum_sub(skb_prev->csum,
1217                                                           skb->csum);
1218                                 pskb_trim_unique(skb_prev, maxfraglen);
1219                         }
1220
1221                         /*
1222                          * Put the packet on the pending queue.
1223                          */
1224                         __skb_queue_tail(&sk->sk_write_queue, skb);
1225                         continue;
1226                 }
1227
1228                 i = skb_shinfo(skb)->nr_frags;
1229                 if (len > size)
1230                         len = size;
1231                 if (skb_can_coalesce(skb, i, page, offset)) {
1232                         skb_shinfo(skb)->frags[i-1].size += len;
1233                 } else if (i < MAX_SKB_FRAGS) {
1234                         get_page(page);
1235                         skb_fill_page_desc(skb, i, page, offset, len);
1236                 } else {
1237                         err = -EMSGSIZE;
1238                         goto error;
1239                 }
1240
1241                 if (skb->ip_summed == CHECKSUM_NONE) {
1242                         __wsum csum;
1243                         csum = csum_page(page, offset, len);
1244                         skb->csum = csum_block_add(skb->csum, csum, skb->len);
1245                 }
1246
1247                 skb->len += len;
1248                 skb->data_len += len;
1249                 skb->truesize += len;
1250                 atomic_add(len, &sk->sk_wmem_alloc);
1251                 offset += len;
1252                 size -= len;
1253         }
1254         return 0;
1255
1256 error:
1257         cork->length -= size;
1258         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1259         return err;
1260 }
1261
1262 static void ip_cork_release(struct inet_cork *cork)
1263 {
1264         cork->flags &= ~IPCORK_OPT;
1265         kfree(cork->opt);
1266         cork->opt = NULL;
1267         dst_release(cork->dst);
1268         cork->dst = NULL;
1269 }
1270
1271 /*
1272  *      Combined all pending IP fragments on the socket as one IP datagram
1273  *      and push them out.
1274  */
1275 struct sk_buff *__ip_make_skb(struct sock *sk,
1276                               struct flowi4 *fl4,
1277                               struct sk_buff_head *queue,
1278                               struct inet_cork *cork)
1279 {
1280         struct sk_buff *skb, *tmp_skb;
1281         struct sk_buff **tail_skb;
1282         struct inet_sock *inet = inet_sk(sk);
1283         struct net *net = sock_net(sk);
1284         struct ip_options *opt = NULL;
1285         struct rtable *rt = (struct rtable *)cork->dst;
1286         struct iphdr *iph;
1287         __be16 df = 0;
1288         __u8 ttl;
1289
1290         if ((skb = __skb_dequeue(queue)) == NULL)
1291                 goto out;
1292         tail_skb = &(skb_shinfo(skb)->frag_list);
1293
1294         /* move skb->data to ip header from ext header */
1295         if (skb->data < skb_network_header(skb))
1296                 __skb_pull(skb, skb_network_offset(skb));
1297         while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1298                 __skb_pull(tmp_skb, skb_network_header_len(skb));
1299                 *tail_skb = tmp_skb;
1300                 tail_skb = &(tmp_skb->next);
1301                 skb->len += tmp_skb->len;
1302                 skb->data_len += tmp_skb->len;
1303                 skb->truesize += tmp_skb->truesize;
1304                 tmp_skb->destructor = NULL;
1305                 tmp_skb->sk = NULL;
1306         }
1307
1308         /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1309          * to fragment the frame generated here. No matter, what transforms
1310          * how transforms change size of the packet, it will come out.
1311          */
1312         if (inet->pmtudisc < IP_PMTUDISC_DO)
1313                 skb->local_df = 1;
1314
1315         /* DF bit is set when we want to see DF on outgoing frames.
1316          * If local_df is set too, we still allow to fragment this frame
1317          * locally. */
1318         if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1319             (skb->len <= dst_mtu(&rt->dst) &&
1320              ip_dont_fragment(sk, &rt->dst)))
1321                 df = htons(IP_DF);
1322
1323         if (cork->flags & IPCORK_OPT)
1324                 opt = cork->opt;
1325
1326         if (rt->rt_type == RTN_MULTICAST)
1327                 ttl = inet->mc_ttl;
1328         else
1329                 ttl = ip_select_ttl(inet, &rt->dst);
1330
1331         iph = (struct iphdr *)skb->data;
1332         iph->version = 4;
1333         iph->ihl = 5;
1334         iph->tos = inet->tos;
1335         iph->frag_off = df;
1336         ip_select_ident(iph, &rt->dst, sk);
1337         iph->ttl = ttl;
1338         iph->protocol = sk->sk_protocol;
1339         iph->saddr = fl4->saddr;
1340         iph->daddr = fl4->daddr;
1341
1342         if (opt) {
1343                 iph->ihl += opt->optlen>>2;
1344                 ip_options_build(skb, opt, cork->addr, rt, 0);
1345         }
1346
1347         skb->priority = sk->sk_priority;
1348         skb->mark = sk->sk_mark;
1349         /*
1350          * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1351          * on dst refcount
1352          */
1353         cork->dst = NULL;
1354         skb_dst_set(skb, &rt->dst);
1355
1356         if (iph->protocol == IPPROTO_ICMP)
1357                 icmp_out_count(net, ((struct icmphdr *)
1358                         skb_transport_header(skb))->type);
1359
1360         ip_cork_release(cork);
1361 out:
1362         return skb;
1363 }
1364
1365 int ip_send_skb(struct sk_buff *skb)
1366 {
1367         struct net *net = sock_net(skb->sk);
1368         int err;
1369
1370         err = ip_local_out(skb);
1371         if (err) {
1372                 if (err > 0)
1373                         err = net_xmit_errno(err);
1374                 if (err)
1375                         IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1376         }
1377
1378         return err;
1379 }
1380
1381 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1382 {
1383         struct sk_buff *skb;
1384
1385         skb = ip_finish_skb(sk, fl4);
1386         if (!skb)
1387                 return 0;
1388
1389         /* Netfilter gets whole the not fragmented skb. */
1390         return ip_send_skb(skb);
1391 }
1392
1393 /*
1394  *      Throw away all pending data on the socket.
1395  */
1396 static void __ip_flush_pending_frames(struct sock *sk,
1397                                       struct sk_buff_head *queue,
1398                                       struct inet_cork *cork)
1399 {
1400         struct sk_buff *skb;
1401
1402         while ((skb = __skb_dequeue_tail(queue)) != NULL)
1403                 kfree_skb(skb);
1404
1405         ip_cork_release(cork);
1406 }
1407
1408 void ip_flush_pending_frames(struct sock *sk)
1409 {
1410         __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1411 }
1412
1413 struct sk_buff *ip_make_skb(struct sock *sk,
1414                             struct flowi4 *fl4,
1415                             int getfrag(void *from, char *to, int offset,
1416                                         int len, int odd, struct sk_buff *skb),
1417                             void *from, int length, int transhdrlen,
1418                             struct ipcm_cookie *ipc, struct rtable **rtp,
1419                             unsigned int flags)
1420 {
1421         struct inet_cork cork;
1422         struct sk_buff_head queue;
1423         int err;
1424
1425         if (flags & MSG_PROBE)
1426                 return NULL;
1427
1428         __skb_queue_head_init(&queue);
1429
1430         cork.flags = 0;
1431         cork.addr = 0;
1432         cork.opt = NULL;
1433         err = ip_setup_cork(sk, &cork, ipc, rtp);
1434         if (err)
1435                 return ERR_PTR(err);
1436
1437         err = __ip_append_data(sk, fl4, &queue, &cork, getfrag,
1438                                from, length, transhdrlen, flags);
1439         if (err) {
1440                 __ip_flush_pending_frames(sk, &queue, &cork);
1441                 return ERR_PTR(err);
1442         }
1443
1444         return __ip_make_skb(sk, fl4, &queue, &cork);
1445 }
1446
1447 /*
1448  *      Fetch data from kernel space and fill in checksum if needed.
1449  */
1450 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1451                               int len, int odd, struct sk_buff *skb)
1452 {
1453         __wsum csum;
1454
1455         csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1456         skb->csum = csum_block_add(skb->csum, csum, odd);
1457         return 0;
1458 }
1459
1460 /*
1461  *      Generic function to send a packet as reply to another packet.
1462  *      Used to send TCP resets so far. ICMP should use this function too.
1463  *
1464  *      Should run single threaded per socket because it uses the sock
1465  *      structure to pass arguments.
1466  */
1467 void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
1468                    struct ip_reply_arg *arg, unsigned int len)
1469 {
1470         struct inet_sock *inet = inet_sk(sk);
1471         struct ip_options_data replyopts;
1472         struct ipcm_cookie ipc;
1473         struct flowi4 fl4;
1474         struct rtable *rt = skb_rtable(skb);
1475
1476         if (ip_options_echo(&replyopts.opt.opt, skb))
1477                 return;
1478
1479         ipc.addr = daddr;
1480         ipc.opt = NULL;
1481         ipc.tx_flags = 0;
1482
1483         if (replyopts.opt.opt.optlen) {
1484                 ipc.opt = &replyopts.opt;
1485
1486                 if (replyopts.opt.opt.srr)
1487                         daddr = replyopts.opt.opt.faddr;
1488         }
1489
1490         flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1491                            RT_TOS(ip_hdr(skb)->tos),
1492                            RT_SCOPE_UNIVERSE, sk->sk_protocol,
1493                            ip_reply_arg_flowi_flags(arg),
1494                            daddr, rt->rt_spec_dst,
1495                            tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1496         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1497         rt = ip_route_output_key(sock_net(sk), &fl4);
1498         if (IS_ERR(rt))
1499                 return;
1500
1501         /* And let IP do all the hard work.
1502
1503            This chunk is not reenterable, hence spinlock.
1504            Note that it uses the fact, that this function is called
1505            with locally disabled BH and that sk cannot be already spinlocked.
1506          */
1507         bh_lock_sock(sk);
1508         inet->tos = ip_hdr(skb)->tos;
1509         sk->sk_priority = skb->priority;
1510         sk->sk_protocol = ip_hdr(skb)->protocol;
1511         sk->sk_bound_dev_if = arg->bound_dev_if;
1512         ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1513                        &ipc, &rt, MSG_DONTWAIT);
1514         if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1515                 if (arg->csumoffset >= 0)
1516                         *((__sum16 *)skb_transport_header(skb) +
1517                           arg->csumoffset) = csum_fold(csum_add(skb->csum,
1518                                                                 arg->csum));
1519                 skb->ip_summed = CHECKSUM_NONE;
1520                 ip_push_pending_frames(sk, &fl4);
1521         }
1522
1523         bh_unlock_sock(sk);
1524
1525         ip_rt_put(rt);
1526 }
1527
1528 void __init ip_init(void)
1529 {
1530         ip_rt_init();
1531         inet_initpeers();
1532
1533 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1534         igmp_mc_proc_init();
1535 #endif
1536 }