linux/net/ipv4/ip_output.c
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   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 <linux/module.h>
  47#include <linux/types.h>
  48#include <linux/kernel.h>
  49#include <linux/mm.h>
  50#include <linux/string.h>
  51#include <linux/errno.h>
  52#include <linux/highmem.h>
  53#include <linux/slab.h>
  54
  55#include <linux/socket.h>
  56#include <linux/sockios.h>
  57#include <linux/in.h>
  58#include <linux/inet.h>
  59#include <linux/netdevice.h>
  60#include <linux/etherdevice.h>
  61#include <linux/proc_fs.h>
  62#include <linux/stat.h>
  63#include <linux/init.h>
  64
  65#include <net/snmp.h>
  66#include <net/ip.h>
  67#include <net/protocol.h>
  68#include <net/route.h>
  69#include <net/xfrm.h>
  70#include <linux/skbuff.h>
  71#include <net/sock.h>
  72#include <net/arp.h>
  73#include <net/icmp.h>
  74#include <net/checksum.h>
  75#include <net/inetpeer.h>
  76#include <linux/igmp.h>
  77#include <linux/netfilter_ipv4.h>
  78#include <linux/netfilter_bridge.h>
  79#include <linux/mroute.h>
  80#include <linux/netlink.h>
  81#include <linux/tcp.h>
  82
  83int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
  84EXPORT_SYMBOL(sysctl_ip_default_ttl);
  85
  86/* Generate a checksum for an outgoing IP datagram. */
  87__inline__ void ip_send_check(struct iphdr *iph)
  88{
  89        iph->check = 0;
  90        iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  91}
  92EXPORT_SYMBOL(ip_send_check);
  93
  94int __ip_local_out(struct sk_buff *skb)
  95{
  96        struct iphdr *iph = ip_hdr(skb);
  97
  98        iph->tot_len = htons(skb->len);
  99        ip_send_check(iph);
 100        return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
 101                       skb_dst(skb)->dev, dst_output);
 102}
 103
 104int ip_local_out(struct sk_buff *skb)
 105{
 106        int err;
 107
 108        err = __ip_local_out(skb);
 109        if (likely(err == 1))
 110                err = dst_output(skb);
 111
 112        return err;
 113}
 114EXPORT_SYMBOL_GPL(ip_local_out);
 115
 116static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 117{
 118        int ttl = inet->uc_ttl;
 119
 120        if (ttl < 0)
 121                ttl = ip4_dst_hoplimit(dst);
 122        return ttl;
 123}
 124
 125/*
 126 *              Add an ip header to a skbuff and send it out.
 127 *
 128 */
 129int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 130                          __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 131{
 132        struct inet_sock *inet = inet_sk(sk);
 133        struct rtable *rt = skb_rtable(skb);
 134        struct iphdr *iph;
 135
 136        /* Build the IP header. */
 137        skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 138        skb_reset_network_header(skb);
 139        iph = ip_hdr(skb);
 140        iph->version  = 4;
 141        iph->ihl      = 5;
 142        iph->tos      = inet->tos;
 143        if (ip_dont_fragment(sk, &rt->dst))
 144                iph->frag_off = htons(IP_DF);
 145        else
 146                iph->frag_off = 0;
 147        iph->ttl      = ip_select_ttl(inet, &rt->dst);
 148        iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 149        iph->saddr    = saddr;
 150        iph->protocol = sk->sk_protocol;
 151        ip_select_ident(iph, &rt->dst, sk);
 152
 153        if (opt && opt->opt.optlen) {
 154                iph->ihl += opt->opt.optlen>>2;
 155                ip_options_build(skb, &opt->opt, daddr, rt, 0);
 156        }
 157
 158        skb->priority = sk->sk_priority;
 159        skb->mark = sk->sk_mark;
 160
 161        /* Send it out. */
 162        return ip_local_out(skb);
 163}
 164EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 165
 166static inline int ip_finish_output2(struct sk_buff *skb)
 167{
 168        struct dst_entry *dst = skb_dst(skb);
 169        struct rtable *rt = (struct rtable *)dst;
 170        struct net_device *dev = dst->dev;
 171        unsigned int hh_len = LL_RESERVED_SPACE(dev);
 172        struct neighbour *neigh;
 173        u32 nexthop;
 174
 175        if (rt->rt_type == RTN_MULTICAST) {
 176                IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
 177        } else if (rt->rt_type == RTN_BROADCAST)
 178                IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
 179
 180        /* Be paranoid, rather than too clever. */
 181        if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 182                struct sk_buff *skb2;
 183
 184                skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 185                if (skb2 == NULL) {
 186                        kfree_skb(skb);
 187                        return -ENOMEM;
 188                }
 189                if (skb->sk)
 190                        skb_set_owner_w(skb2, skb->sk);
 191                consume_skb(skb);
 192                skb = skb2;
 193        }
 194
 195        rcu_read_lock_bh();
 196        nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
 197        neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
 198        if (unlikely(!neigh))
 199                neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
 200        if (!IS_ERR(neigh)) {
 201                int res = dst_neigh_output(dst, neigh, skb);
 202
 203                rcu_read_unlock_bh();
 204                return res;
 205        }
 206        rcu_read_unlock_bh();
 207
 208        net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
 209                            __func__);
 210        kfree_skb(skb);
 211        return -EINVAL;
 212}
 213
 214static inline int ip_skb_dst_mtu(struct sk_buff *skb)
 215{
 216        struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
 217
 218        return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
 219               skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
 220}
 221
 222static int ip_finish_output(struct sk_buff *skb)
 223{
 224#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 225        /* Policy lookup after SNAT yielded a new policy */
 226        if (skb_dst(skb)->xfrm != NULL) {
 227                IPCB(skb)->flags |= IPSKB_REROUTED;
 228                return dst_output(skb);
 229        }
 230#endif
 231        if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
 232                return ip_fragment(skb, ip_finish_output2);
 233        else
 234                return ip_finish_output2(skb);
 235}
 236
 237int ip_mc_output(struct sk_buff *skb)
 238{
 239        struct sock *sk = skb->sk;
 240        struct rtable *rt = skb_rtable(skb);
 241        struct net_device *dev = rt->dst.dev;
 242
 243        /*
 244         *      If the indicated interface is up and running, send the packet.
 245         */
 246        IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 247
 248        skb->dev = dev;
 249        skb->protocol = htons(ETH_P_IP);
 250
 251        /*
 252         *      Multicasts are looped back for other local users
 253         */
 254
 255        if (rt->rt_flags&RTCF_MULTICAST) {
 256                if (sk_mc_loop(sk)
 257#ifdef CONFIG_IP_MROUTE
 258                /* Small optimization: do not loopback not local frames,
 259                   which returned after forwarding; they will be  dropped
 260                   by ip_mr_input in any case.
 261                   Note, that local frames are looped back to be delivered
 262                   to local recipients.
 263
 264                   This check is duplicated in ip_mr_input at the moment.
 265                 */
 266                    &&
 267                    ((rt->rt_flags & RTCF_LOCAL) ||
 268                     !(IPCB(skb)->flags & IPSKB_FORWARDED))
 269#endif
 270                   ) {
 271                        struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 272                        if (newskb)
 273                                NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 274                                        newskb, NULL, newskb->dev,
 275                                        dev_loopback_xmit);
 276                }
 277
 278                /* Multicasts with ttl 0 must not go beyond the host */
 279
 280                if (ip_hdr(skb)->ttl == 0) {
 281                        kfree_skb(skb);
 282                        return 0;
 283                }
 284        }
 285
 286        if (rt->rt_flags&RTCF_BROADCAST) {
 287                struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 288                if (newskb)
 289                        NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
 290                                NULL, newskb->dev, dev_loopback_xmit);
 291        }
 292
 293        return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
 294                            skb->dev, ip_finish_output,
 295                            !(IPCB(skb)->flags & IPSKB_REROUTED));
 296}
 297
 298int ip_output(struct sk_buff *skb)
 299{
 300        struct net_device *dev = skb_dst(skb)->dev;
 301
 302        IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 303
 304        skb->dev = dev;
 305        skb->protocol = htons(ETH_P_IP);
 306
 307        return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
 308                            ip_finish_output,
 309                            !(IPCB(skb)->flags & IPSKB_REROUTED));
 310}
 311
 312/*
 313 * copy saddr and daddr, possibly using 64bit load/stores
 314 * Equivalent to :
 315 *   iph->saddr = fl4->saddr;
 316 *   iph->daddr = fl4->daddr;
 317 */
 318static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
 319{
 320        BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
 321                     offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
 322        memcpy(&iph->saddr, &fl4->saddr,
 323               sizeof(fl4->saddr) + sizeof(fl4->daddr));
 324}
 325
 326int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
 327{
 328        struct sock *sk = skb->sk;
 329        struct inet_sock *inet = inet_sk(sk);
 330        struct ip_options_rcu *inet_opt;
 331        struct flowi4 *fl4;
 332        struct rtable *rt;
 333        struct iphdr *iph;
 334        int res;
 335
 336        /* Skip all of this if the packet is already routed,
 337         * f.e. by something like SCTP.
 338         */
 339        rcu_read_lock();
 340        inet_opt = rcu_dereference(inet->inet_opt);
 341        fl4 = &fl->u.ip4;
 342        rt = skb_rtable(skb);
 343        if (rt != NULL)
 344                goto packet_routed;
 345
 346        /* Make sure we can route this packet. */
 347        rt = (struct rtable *)__sk_dst_check(sk, 0);
 348        if (rt == NULL) {
 349                __be32 daddr;
 350
 351                /* Use correct destination address if we have options. */
 352                daddr = inet->inet_daddr;
 353                if (inet_opt && inet_opt->opt.srr)
 354                        daddr = inet_opt->opt.faddr;
 355
 356                /* If this fails, retransmit mechanism of transport layer will
 357                 * keep trying until route appears or the connection times
 358                 * itself out.
 359                 */
 360                rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 361                                           daddr, inet->inet_saddr,
 362                                           inet->inet_dport,
 363                                           inet->inet_sport,
 364                                           sk->sk_protocol,
 365                                           RT_CONN_FLAGS(sk),
 366                                           sk->sk_bound_dev_if);
 367                if (IS_ERR(rt))
 368                        goto no_route;
 369                sk_setup_caps(sk, &rt->dst);
 370        }
 371        skb_dst_set_noref(skb, &rt->dst);
 372
 373packet_routed:
 374        if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
 375                goto no_route;
 376
 377        /* OK, we know where to send it, allocate and build IP header. */
 378        skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 379        skb_reset_network_header(skb);
 380        iph = ip_hdr(skb);
 381        *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 382        if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
 383                iph->frag_off = htons(IP_DF);
 384        else
 385                iph->frag_off = 0;
 386        iph->ttl      = ip_select_ttl(inet, &rt->dst);
 387        iph->protocol = sk->sk_protocol;
 388        ip_copy_addrs(iph, fl4);
 389
 390        /* Transport layer set skb->h.foo itself. */
 391
 392        if (inet_opt && inet_opt->opt.optlen) {
 393                iph->ihl += inet_opt->opt.optlen >> 2;
 394                ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 395        }
 396
 397        ip_select_ident_more(iph, &rt->dst, sk,
 398                             (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 399
 400        skb->priority = sk->sk_priority;
 401        skb->mark = sk->sk_mark;
 402
 403        res = ip_local_out(skb);
 404        rcu_read_unlock();
 405        return res;
 406
 407no_route:
 408        rcu_read_unlock();
 409        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 410        kfree_skb(skb);
 411        return -EHOSTUNREACH;
 412}
 413EXPORT_SYMBOL(ip_queue_xmit);
 414
 415
 416static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 417{
 418        to->pkt_type = from->pkt_type;
 419        to->priority = from->priority;
 420        to->protocol = from->protocol;
 421        skb_dst_drop(to);
 422        skb_dst_copy(to, from);
 423        to->dev = from->dev;
 424        to->mark = from->mark;
 425
 426        /* Copy the flags to each fragment. */
 427        IPCB(to)->flags = IPCB(from)->flags;
 428
 429#ifdef CONFIG_NET_SCHED
 430        to->tc_index = from->tc_index;
 431#endif
 432        nf_copy(to, from);
 433#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
 434    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 435        to->nf_trace = from->nf_trace;
 436#endif
 437#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 438        to->ipvs_property = from->ipvs_property;
 439#endif
 440        skb_copy_secmark(to, from);
 441}
 442
 443/*
 444 *      This IP datagram is too large to be sent in one piece.  Break it up into
 445 *      smaller pieces (each of size equal to IP header plus
 446 *      a block of the data of the original IP data part) that will yet fit in a
 447 *      single device frame, and queue such a frame for sending.
 448 */
 449
 450int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 451{
 452        struct iphdr *iph;
 453        int ptr;
 454        struct net_device *dev;
 455        struct sk_buff *skb2;
 456        unsigned int mtu, hlen, left, len, ll_rs;
 457        int offset;
 458        __be16 not_last_frag;
 459        struct rtable *rt = skb_rtable(skb);
 460        int err = 0;
 461
 462        dev = rt->dst.dev;
 463
 464        /*
 465         *      Point into the IP datagram header.
 466         */
 467
 468        iph = ip_hdr(skb);
 469
 470        if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
 471                     (IPCB(skb)->frag_max_size &&
 472                      IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) {
 473                IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 474                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 475                          htonl(ip_skb_dst_mtu(skb)));
 476                kfree_skb(skb);
 477                return -EMSGSIZE;
 478        }
 479
 480        /*
 481         *      Setup starting values.
 482         */
 483
 484        hlen = iph->ihl * 4;
 485        mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
 486#ifdef CONFIG_BRIDGE_NETFILTER
 487        if (skb->nf_bridge)
 488                mtu -= nf_bridge_mtu_reduction(skb);
 489#endif
 490        IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 491
 492        /* When frag_list is given, use it. First, check its validity:
 493         * some transformers could create wrong frag_list or break existing
 494         * one, it is not prohibited. In this case fall back to copying.
 495         *
 496         * LATER: this step can be merged to real generation of fragments,
 497         * we can switch to copy when see the first bad fragment.
 498         */
 499        if (skb_has_frag_list(skb)) {
 500                struct sk_buff *frag, *frag2;
 501                int first_len = skb_pagelen(skb);
 502
 503                if (first_len - hlen > mtu ||
 504                    ((first_len - hlen) & 7) ||
 505                    ip_is_fragment(iph) ||
 506                    skb_cloned(skb))
 507                        goto slow_path;
 508
 509                skb_walk_frags(skb, frag) {
 510                        /* Correct geometry. */
 511                        if (frag->len > mtu ||
 512                            ((frag->len & 7) && frag->next) ||
 513                            skb_headroom(frag) < hlen)
 514                                goto slow_path_clean;
 515
 516                        /* Partially cloned skb? */
 517                        if (skb_shared(frag))
 518                                goto slow_path_clean;
 519
 520                        BUG_ON(frag->sk);
 521                        if (skb->sk) {
 522                                frag->sk = skb->sk;
 523                                frag->destructor = sock_wfree;
 524                        }
 525                        skb->truesize -= frag->truesize;
 526                }
 527
 528                /* Everything is OK. Generate! */
 529
 530                err = 0;
 531                offset = 0;
 532                frag = skb_shinfo(skb)->frag_list;
 533                skb_frag_list_init(skb);
 534                skb->data_len = first_len - skb_headlen(skb);
 535                skb->len = first_len;
 536                iph->tot_len = htons(first_len);
 537                iph->frag_off = htons(IP_MF);
 538                ip_send_check(iph);
 539
 540                for (;;) {
 541                        /* Prepare header of the next frame,
 542                         * before previous one went down. */
 543                        if (frag) {
 544                                frag->ip_summed = CHECKSUM_NONE;
 545                                skb_reset_transport_header(frag);
 546                                __skb_push(frag, hlen);
 547                                skb_reset_network_header(frag);
 548                                memcpy(skb_network_header(frag), iph, hlen);
 549                                iph = ip_hdr(frag);
 550                                iph->tot_len = htons(frag->len);
 551                                ip_copy_metadata(frag, skb);
 552                                if (offset == 0)
 553                                        ip_options_fragment(frag);
 554                                offset += skb->len - hlen;
 555                                iph->frag_off = htons(offset>>3);
 556                                if (frag->next != NULL)
 557                                        iph->frag_off |= htons(IP_MF);
 558                                /* Ready, complete checksum */
 559                                ip_send_check(iph);
 560                        }
 561
 562                        err = output(skb);
 563
 564                        if (!err)
 565                                IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 566                        if (err || !frag)
 567                                break;
 568
 569                        skb = frag;
 570                        frag = skb->next;
 571                        skb->next = NULL;
 572                }
 573
 574                if (err == 0) {
 575                        IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 576                        return 0;
 577                }
 578
 579                while (frag) {
 580                        skb = frag->next;
 581                        kfree_skb(frag);
 582                        frag = skb;
 583                }
 584                IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 585                return err;
 586
 587slow_path_clean:
 588                skb_walk_frags(skb, frag2) {
 589                        if (frag2 == frag)
 590                                break;
 591                        frag2->sk = NULL;
 592                        frag2->destructor = NULL;
 593                        skb->truesize += frag2->truesize;
 594                }
 595        }
 596
 597slow_path:
 598        left = skb->len - hlen;         /* Space per frame */
 599        ptr = hlen;             /* Where to start from */
 600
 601        /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 602         * we need to make room for the encapsulating header
 603         */
 604        ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
 605
 606        /*
 607         *      Fragment the datagram.
 608         */
 609
 610        offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 611        not_last_frag = iph->frag_off & htons(IP_MF);
 612
 613        /*
 614         *      Keep copying data until we run out.
 615         */
 616
 617        while (left > 0) {
 618                len = left;
 619                /* IF: it doesn't fit, use 'mtu' - the data space left */
 620                if (len > mtu)
 621                        len = mtu;
 622                /* IF: we are not sending up to and including the packet end
 623                   then align the next start on an eight byte boundary */
 624                if (len < left) {
 625                        len &= ~7;
 626                }
 627                /*
 628                 *      Allocate buffer.
 629                 */
 630
 631                if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 632                        NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 633                        err = -ENOMEM;
 634                        goto fail;
 635                }
 636
 637                /*
 638                 *      Set up data on packet
 639                 */
 640
 641                ip_copy_metadata(skb2, skb);
 642                skb_reserve(skb2, ll_rs);
 643                skb_put(skb2, len + hlen);
 644                skb_reset_network_header(skb2);
 645                skb2->transport_header = skb2->network_header + hlen;
 646
 647                /*
 648                 *      Charge the memory for the fragment to any owner
 649                 *      it might possess
 650                 */
 651
 652                if (skb->sk)
 653                        skb_set_owner_w(skb2, skb->sk);
 654
 655                /*
 656                 *      Copy the packet header into the new buffer.
 657                 */
 658
 659                skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
 660
 661                /*
 662                 *      Copy a block of the IP datagram.
 663                 */
 664                if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
 665                        BUG();
 666                left -= len;
 667
 668                /*
 669                 *      Fill in the new header fields.
 670                 */
 671                iph = ip_hdr(skb2);
 672                iph->frag_off = htons((offset >> 3));
 673
 674                /* ANK: dirty, but effective trick. Upgrade options only if
 675                 * the segment to be fragmented was THE FIRST (otherwise,
 676                 * options are already fixed) and make it ONCE
 677                 * on the initial skb, so that all the following fragments
 678                 * will inherit fixed options.
 679                 */
 680                if (offset == 0)
 681                        ip_options_fragment(skb);
 682
 683                /*
 684                 *      Added AC : If we are fragmenting a fragment that's not the
 685                 *                 last fragment then keep MF on each bit
 686                 */
 687                if (left > 0 || not_last_frag)
 688                        iph->frag_off |= htons(IP_MF);
 689                ptr += len;
 690                offset += len;
 691
 692                /*
 693                 *      Put this fragment into the sending queue.
 694                 */
 695                iph->tot_len = htons(len + hlen);
 696
 697                ip_send_check(iph);
 698
 699                err = output(skb2);
 700                if (err)
 701                        goto fail;
 702
 703                IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 704        }
 705        consume_skb(skb);
 706        IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 707        return err;
 708
 709fail:
 710        kfree_skb(skb);
 711        IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 712        return err;
 713}
 714EXPORT_SYMBOL(ip_fragment);
 715
 716int
 717ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 718{
 719        struct iovec *iov = from;
 720
 721        if (skb->ip_summed == CHECKSUM_PARTIAL) {
 722                if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 723                        return -EFAULT;
 724        } else {
 725                __wsum csum = 0;
 726                if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 727                        return -EFAULT;
 728                skb->csum = csum_block_add(skb->csum, csum, odd);
 729        }
 730        return 0;
 731}
 732EXPORT_SYMBOL(ip_generic_getfrag);
 733
 734static inline __wsum
 735csum_page(struct page *page, int offset, int copy)
 736{
 737        char *kaddr;
 738        __wsum csum;
 739        kaddr = kmap(page);
 740        csum = csum_partial(kaddr + offset, copy, 0);
 741        kunmap(page);
 742        return csum;
 743}
 744
 745static inline int ip_ufo_append_data(struct sock *sk,
 746                        struct sk_buff_head *queue,
 747                        int getfrag(void *from, char *to, int offset, int len,
 748                               int odd, struct sk_buff *skb),
 749                        void *from, int length, int hh_len, int fragheaderlen,
 750                        int transhdrlen, int maxfraglen, unsigned int flags)
 751{
 752        struct sk_buff *skb;
 753        int err;
 754
 755        /* There is support for UDP fragmentation offload by network
 756         * device, so create one single skb packet containing complete
 757         * udp datagram
 758         */
 759        if ((skb = skb_peek_tail(queue)) == NULL) {
 760                skb = sock_alloc_send_skb(sk,
 761                        hh_len + fragheaderlen + transhdrlen + 20,
 762                        (flags & MSG_DONTWAIT), &err);
 763
 764                if (skb == NULL)
 765                        return err;
 766
 767                /* reserve space for Hardware header */
 768                skb_reserve(skb, hh_len);
 769
 770                /* create space for UDP/IP header */
 771                skb_put(skb, fragheaderlen + transhdrlen);
 772
 773                /* initialize network header pointer */
 774                skb_reset_network_header(skb);
 775
 776                /* initialize protocol header pointer */
 777                skb->transport_header = skb->network_header + fragheaderlen;
 778
 779                skb->ip_summed = CHECKSUM_PARTIAL;
 780                skb->csum = 0;
 781
 782                /* specify the length of each IP datagram fragment */
 783                skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
 784                skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 785                __skb_queue_tail(queue, skb);
 786        }
 787
 788        return skb_append_datato_frags(sk, skb, getfrag, from,
 789                                       (length - transhdrlen));
 790}
 791
 792static int __ip_append_data(struct sock *sk,
 793                            struct flowi4 *fl4,
 794                            struct sk_buff_head *queue,
 795                            struct inet_cork *cork,
 796                            struct page_frag *pfrag,
 797                            int getfrag(void *from, char *to, int offset,
 798                                        int len, int odd, struct sk_buff *skb),
 799                            void *from, int length, int transhdrlen,
 800                            unsigned int flags)
 801{
 802        struct inet_sock *inet = inet_sk(sk);
 803        struct sk_buff *skb;
 804
 805        struct ip_options *opt = cork->opt;
 806        int hh_len;
 807        int exthdrlen;
 808        int mtu;
 809        int copy;
 810        int err;
 811        int offset = 0;
 812        unsigned int maxfraglen, fragheaderlen;
 813        int csummode = CHECKSUM_NONE;
 814        struct rtable *rt = (struct rtable *)cork->dst;
 815
 816        skb = skb_peek_tail(queue);
 817
 818        exthdrlen = !skb ? rt->dst.header_len : 0;
 819        mtu = cork->fragsize;
 820
 821        hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 822
 823        fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 824        maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 825
 826        if (cork->length + length > 0xFFFF - fragheaderlen) {
 827                ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 828                               mtu-exthdrlen);
 829                return -EMSGSIZE;
 830        }
 831
 832        /*
 833         * transhdrlen > 0 means that this is the first fragment and we wish
 834         * it won't be fragmented in the future.
 835         */
 836        if (transhdrlen &&
 837            length + fragheaderlen <= mtu &&
 838            rt->dst.dev->features & NETIF_F_V4_CSUM &&
 839            !exthdrlen)
 840                csummode = CHECKSUM_PARTIAL;
 841
 842        cork->length += length;
 843        if (((length > mtu) || (skb && skb_is_gso(skb))) &&
 844            (sk->sk_protocol == IPPROTO_UDP) &&
 845            (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
 846                err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 847                                         hh_len, fragheaderlen, transhdrlen,
 848                                         maxfraglen, flags);
 849                if (err)
 850                        goto error;
 851                return 0;
 852        }
 853
 854        /* So, what's going on in the loop below?
 855         *
 856         * We use calculated fragment length to generate chained skb,
 857         * each of segments is IP fragment ready for sending to network after
 858         * adding appropriate IP header.
 859         */
 860
 861        if (!skb)
 862                goto alloc_new_skb;
 863
 864        while (length > 0) {
 865                /* Check if the remaining data fits into current packet. */
 866                copy = mtu - skb->len;
 867                if (copy < length)
 868                        copy = maxfraglen - skb->len;
 869                if (copy <= 0) {
 870                        char *data;
 871                        unsigned int datalen;
 872                        unsigned int fraglen;
 873                        unsigned int fraggap;
 874                        unsigned int alloclen;
 875                        struct sk_buff *skb_prev;
 876alloc_new_skb:
 877                        skb_prev = skb;
 878                        if (skb_prev)
 879                                fraggap = skb_prev->len - maxfraglen;
 880                        else
 881                                fraggap = 0;
 882
 883                        /*
 884                         * If remaining data exceeds the mtu,
 885                         * we know we need more fragment(s).
 886                         */
 887                        datalen = length + fraggap;
 888                        if (datalen > mtu - fragheaderlen)
 889                                datalen = maxfraglen - fragheaderlen;
 890                        fraglen = datalen + fragheaderlen;
 891
 892                        if ((flags & MSG_MORE) &&
 893                            !(rt->dst.dev->features&NETIF_F_SG))
 894                                alloclen = mtu;
 895                        else
 896                                alloclen = fraglen;
 897
 898                        alloclen += exthdrlen;
 899
 900                        /* The last fragment gets additional space at tail.
 901                         * Note, with MSG_MORE we overallocate on fragments,
 902                         * because we have no idea what fragment will be
 903                         * the last.
 904                         */
 905                        if (datalen == length + fraggap)
 906                                alloclen += rt->dst.trailer_len;
 907
 908                        if (transhdrlen) {
 909                                skb = sock_alloc_send_skb(sk,
 910                                                alloclen + hh_len + 15,
 911                                                (flags & MSG_DONTWAIT), &err);
 912                        } else {
 913                                skb = NULL;
 914                                if (atomic_read(&sk->sk_wmem_alloc) <=
 915                                    2 * sk->sk_sndbuf)
 916                                        skb = sock_wmalloc(sk,
 917                                                           alloclen + hh_len + 15, 1,
 918                                                           sk->sk_allocation);
 919                                if (unlikely(skb == NULL))
 920                                        err = -ENOBUFS;
 921                                else
 922                                        /* only the initial fragment is
 923                                           time stamped */
 924                                        cork->tx_flags = 0;
 925                        }
 926                        if (skb == NULL)
 927                                goto error;
 928
 929                        /*
 930                         *      Fill in the control structures
 931                         */
 932                        skb->ip_summed = csummode;
 933                        skb->csum = 0;
 934                        skb_reserve(skb, hh_len);
 935                        skb_shinfo(skb)->tx_flags = cork->tx_flags;
 936
 937                        /*
 938                         *      Find where to start putting bytes.
 939                         */
 940                        data = skb_put(skb, fraglen + exthdrlen);
 941                        skb_set_network_header(skb, exthdrlen);
 942                        skb->transport_header = (skb->network_header +
 943                                                 fragheaderlen);
 944                        data += fragheaderlen + exthdrlen;
 945
 946                        if (fraggap) {
 947                                skb->csum = skb_copy_and_csum_bits(
 948                                        skb_prev, maxfraglen,
 949                                        data + transhdrlen, fraggap, 0);
 950                                skb_prev->csum = csum_sub(skb_prev->csum,
 951                                                          skb->csum);
 952                                data += fraggap;
 953                                pskb_trim_unique(skb_prev, maxfraglen);
 954                        }
 955
 956                        copy = datalen - transhdrlen - fraggap;
 957                        if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 958                                err = -EFAULT;
 959                                kfree_skb(skb);
 960                                goto error;
 961                        }
 962
 963                        offset += copy;
 964                        length -= datalen - fraggap;
 965                        transhdrlen = 0;
 966                        exthdrlen = 0;
 967                        csummode = CHECKSUM_NONE;
 968
 969                        /*
 970                         * Put the packet on the pending queue.
 971                         */
 972                        __skb_queue_tail(queue, skb);
 973                        continue;
 974                }
 975
 976                if (copy > length)
 977                        copy = length;
 978
 979                if (!(rt->dst.dev->features&NETIF_F_SG)) {
 980                        unsigned int off;
 981
 982                        off = skb->len;
 983                        if (getfrag(from, skb_put(skb, copy),
 984                                        offset, copy, off, skb) < 0) {
 985                                __skb_trim(skb, off);
 986                                err = -EFAULT;
 987                                goto error;
 988                        }
 989                } else {
 990                        int i = skb_shinfo(skb)->nr_frags;
 991
 992                        err = -ENOMEM;
 993                        if (!sk_page_frag_refill(sk, pfrag))
 994                                goto error;
 995
 996                        if (!skb_can_coalesce(skb, i, pfrag->page,
 997                                              pfrag->offset)) {
 998                                err = -EMSGSIZE;
 999                                if (i == MAX_SKB_FRAGS)
1000                                        goto error;
1001
1002                                __skb_fill_page_desc(skb, i, pfrag->page,
1003                                                     pfrag->offset, 0);
1004                                skb_shinfo(skb)->nr_frags = ++i;
1005                                get_page(pfrag->page);
1006                        }
1007                        copy = min_t(int, copy, pfrag->size - pfrag->offset);
1008                        if (getfrag(from,
1009                                    page_address(pfrag->page) + pfrag->offset,
1010                                    offset, copy, skb->len, skb) < 0)
1011                                goto error_efault;
1012
1013                        pfrag->offset += copy;
1014                        skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1015                        skb->len += copy;
1016                        skb->data_len += copy;
1017                        skb->truesize += copy;
1018                        atomic_add(copy, &sk->sk_wmem_alloc);
1019                }
1020                offset += copy;
1021                length -= copy;
1022        }
1023
1024        return 0;
1025
1026error_efault:
1027        err = -EFAULT;
1028error:
1029        cork->length -= length;
1030        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1031        return err;
1032}
1033
1034static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1035                         struct ipcm_cookie *ipc, struct rtable **rtp)
1036{
1037        struct inet_sock *inet = inet_sk(sk);
1038        struct ip_options_rcu *opt;
1039        struct rtable *rt;
1040
1041        /*
1042         * setup for corking.
1043         */
1044        opt = ipc->opt;
1045        if (opt) {
1046                if (cork->opt == NULL) {
1047                        cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1048                                            sk->sk_allocation);
1049                        if (unlikely(cork->opt == NULL))
1050                                return -ENOBUFS;
1051                }
1052                memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1053                cork->flags |= IPCORK_OPT;
1054                cork->addr = ipc->addr;
1055        }
1056        rt = *rtp;
1057        if (unlikely(!rt))
1058                return -EFAULT;
1059        /*
1060         * We steal reference to this route, caller should not release it
1061         */
1062        *rtp = NULL;
1063        cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1064                         rt->dst.dev->mtu : dst_mtu(&rt->dst);
1065        cork->dst = &rt->dst;
1066        cork->length = 0;
1067        cork->tx_flags = ipc->tx_flags;
1068
1069        return 0;
1070}
1071
1072/*
1073 *      ip_append_data() and ip_append_page() can make one large IP datagram
1074 *      from many pieces of data. Each pieces will be holded on the socket
1075 *      until ip_push_pending_frames() is called. Each piece can be a page
1076 *      or non-page data.
1077 *
1078 *      Not only UDP, other transport protocols - e.g. raw sockets - can use
1079 *      this interface potentially.
1080 *
1081 *      LATER: length must be adjusted by pad at tail, when it is required.
1082 */
1083int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1084                   int getfrag(void *from, char *to, int offset, int len,
1085                               int odd, struct sk_buff *skb),
1086                   void *from, int length, int transhdrlen,
1087                   struct ipcm_cookie *ipc, struct rtable **rtp,
1088                   unsigned int flags)
1089{
1090        struct inet_sock *inet = inet_sk(sk);
1091        int err;
1092
1093        if (flags&MSG_PROBE)
1094                return 0;
1095
1096        if (skb_queue_empty(&sk->sk_write_queue)) {
1097                err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1098                if (err)
1099                        return err;
1100        } else {
1101                transhdrlen = 0;
1102        }
1103
1104        return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1105                                sk_page_frag(sk), getfrag,
1106                                from, length, transhdrlen, flags);
1107}
1108
1109ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1110                       int offset, size_t size, int flags)
1111{
1112        struct inet_sock *inet = inet_sk(sk);
1113        struct sk_buff *skb;
1114        struct rtable *rt;
1115        struct ip_options *opt = NULL;
1116        struct inet_cork *cork;
1117        int hh_len;
1118        int mtu;
1119        int len;
1120        int err;
1121        unsigned int maxfraglen, fragheaderlen, fraggap;
1122
1123        if (inet->hdrincl)
1124                return -EPERM;
1125
1126        if (flags&MSG_PROBE)
1127                return 0;
1128
1129        if (skb_queue_empty(&sk->sk_write_queue))
1130                return -EINVAL;
1131
1132        cork = &inet->cork.base;
1133        rt = (struct rtable *)cork->dst;
1134        if (cork->flags & IPCORK_OPT)
1135                opt = cork->opt;
1136
1137        if (!(rt->dst.dev->features&NETIF_F_SG))
1138                return -EOPNOTSUPP;
1139
1140        hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1141        mtu = cork->fragsize;
1142
1143        fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1144        maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1145
1146        if (cork->length + size > 0xFFFF - fragheaderlen) {
1147                ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
1148                return -EMSGSIZE;
1149        }
1150
1151        if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1152                return -EINVAL;
1153
1154        cork->length += size;
1155        if ((size + skb->len > mtu) &&
1156            (sk->sk_protocol == IPPROTO_UDP) &&
1157            (rt->dst.dev->features & NETIF_F_UFO)) {
1158                skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1159                skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1160        }
1161
1162
1163        while (size > 0) {
1164                int i;
1165
1166                if (skb_is_gso(skb))
1167                        len = size;
1168                else {
1169
1170                        /* Check if the remaining data fits into current packet. */
1171                        len = mtu - skb->len;
1172                        if (len < size)
1173                                len = maxfraglen - skb->len;
1174                }
1175                if (len <= 0) {
1176                        struct sk_buff *skb_prev;
1177                        int alloclen;
1178
1179                        skb_prev = skb;
1180                        fraggap = skb_prev->len - maxfraglen;
1181
1182                        alloclen = fragheaderlen + hh_len + fraggap + 15;
1183                        skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1184                        if (unlikely(!skb)) {
1185                                err = -ENOBUFS;
1186                                goto error;
1187                        }
1188
1189                        /*
1190                         *      Fill in the control structures
1191                         */
1192                        skb->ip_summed = CHECKSUM_NONE;
1193                        skb->csum = 0;
1194                        skb_reserve(skb, hh_len);
1195
1196                        /*
1197                         *      Find where to start putting bytes.
1198                         */
1199                        skb_put(skb, fragheaderlen + fraggap);
1200                        skb_reset_network_header(skb);
1201                        skb->transport_header = (skb->network_header +
1202                                                 fragheaderlen);
1203                        if (fraggap) {
1204                                skb->csum = skb_copy_and_csum_bits(skb_prev,
1205                                                                   maxfraglen,
1206                                                    skb_transport_header(skb),
1207                                                                   fraggap, 0);
1208                                skb_prev->csum = csum_sub(skb_prev->csum,
1209                                                          skb->csum);
1210                                pskb_trim_unique(skb_prev, maxfraglen);
1211                        }
1212
1213                        /*
1214                         * Put the packet on the pending queue.
1215                         */
1216                        __skb_queue_tail(&sk->sk_write_queue, skb);
1217                        continue;
1218                }
1219
1220                i = skb_shinfo(skb)->nr_frags;
1221                if (len > size)
1222                        len = size;
1223                if (skb_can_coalesce(skb, i, page, offset)) {
1224                        skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len);
1225                } else if (i < MAX_SKB_FRAGS) {
1226                        get_page(page);
1227                        skb_fill_page_desc(skb, i, page, offset, len);
1228                } else {
1229                        err = -EMSGSIZE;
1230                        goto error;
1231                }
1232
1233                if (skb->ip_summed == CHECKSUM_NONE) {
1234                        __wsum csum;
1235                        csum = csum_page(page, offset, len);
1236                        skb->csum = csum_block_add(skb->csum, csum, skb->len);
1237                }
1238
1239                skb->len += len;
1240                skb->data_len += len;
1241                skb->truesize += len;
1242                atomic_add(len, &sk->sk_wmem_alloc);
1243                offset += len;
1244                size -= len;
1245        }
1246        return 0;
1247
1248error:
1249        cork->length -= size;
1250        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1251        return err;
1252}
1253
1254static void ip_cork_release(struct inet_cork *cork)
1255{
1256        cork->flags &= ~IPCORK_OPT;
1257        kfree(cork->opt);
1258        cork->opt = NULL;
1259        dst_release(cork->dst);
1260        cork->dst = NULL;
1261}
1262
1263/*
1264 *      Combined all pending IP fragments on the socket as one IP datagram
1265 *      and push them out.
1266 */
1267struct sk_buff *__ip_make_skb(struct sock *sk,
1268                              struct flowi4 *fl4,
1269                              struct sk_buff_head *queue,
1270                              struct inet_cork *cork)
1271{
1272        struct sk_buff *skb, *tmp_skb;
1273        struct sk_buff **tail_skb;
1274        struct inet_sock *inet = inet_sk(sk);
1275        struct net *net = sock_net(sk);
1276        struct ip_options *opt = NULL;
1277        struct rtable *rt = (struct rtable *)cork->dst;
1278        struct iphdr *iph;
1279        __be16 df = 0;
1280        __u8 ttl;
1281
1282        if ((skb = __skb_dequeue(queue)) == NULL)
1283                goto out;
1284        tail_skb = &(skb_shinfo(skb)->frag_list);
1285
1286        /* move skb->data to ip header from ext header */
1287        if (skb->data < skb_network_header(skb))
1288                __skb_pull(skb, skb_network_offset(skb));
1289        while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1290                __skb_pull(tmp_skb, skb_network_header_len(skb));
1291                *tail_skb = tmp_skb;
1292                tail_skb = &(tmp_skb->next);
1293                skb->len += tmp_skb->len;
1294                skb->data_len += tmp_skb->len;
1295                skb->truesize += tmp_skb->truesize;
1296                tmp_skb->destructor = NULL;
1297                tmp_skb->sk = NULL;
1298        }
1299
1300        /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1301         * to fragment the frame generated here. No matter, what transforms
1302         * how transforms change size of the packet, it will come out.
1303         */
1304        if (inet->pmtudisc < IP_PMTUDISC_DO)
1305                skb->local_df = 1;
1306
1307        /* DF bit is set when we want to see DF on outgoing frames.
1308         * If local_df is set too, we still allow to fragment this frame
1309         * locally. */
1310        if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1311            (skb->len <= dst_mtu(&rt->dst) &&
1312             ip_dont_fragment(sk, &rt->dst)))
1313                df = htons(IP_DF);
1314
1315        if (cork->flags & IPCORK_OPT)
1316                opt = cork->opt;
1317
1318        if (rt->rt_type == RTN_MULTICAST)
1319                ttl = inet->mc_ttl;
1320        else
1321                ttl = ip_select_ttl(inet, &rt->dst);
1322
1323        iph = (struct iphdr *)skb->data;
1324        iph->version = 4;
1325        iph->ihl = 5;
1326        iph->tos = inet->tos;
1327        iph->frag_off = df;
1328        iph->ttl = ttl;
1329        iph->protocol = sk->sk_protocol;
1330        ip_copy_addrs(iph, fl4);
1331        ip_select_ident(iph, &rt->dst, sk);
1332
1333        if (opt) {
1334                iph->ihl += opt->optlen>>2;
1335                ip_options_build(skb, opt, cork->addr, rt, 0);
1336        }
1337
1338        skb->priority = sk->sk_priority;
1339        skb->mark = sk->sk_mark;
1340        /*
1341         * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1342         * on dst refcount
1343         */
1344        cork->dst = NULL;
1345        skb_dst_set(skb, &rt->dst);
1346
1347        if (iph->protocol == IPPROTO_ICMP)
1348                icmp_out_count(net, ((struct icmphdr *)
1349                        skb_transport_header(skb))->type);
1350
1351        ip_cork_release(cork);
1352out:
1353        return skb;
1354}
1355
1356int ip_send_skb(struct net *net, struct sk_buff *skb)
1357{
1358        int err;
1359
1360        err = ip_local_out(skb);
1361        if (err) {
1362                if (err > 0)
1363                        err = net_xmit_errno(err);
1364                if (err)
1365                        IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1366        }
1367
1368        return err;
1369}
1370
1371int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1372{
1373        struct sk_buff *skb;
1374
1375        skb = ip_finish_skb(sk, fl4);
1376        if (!skb)
1377                return 0;
1378
1379        /* Netfilter gets whole the not fragmented skb. */
1380        return ip_send_skb(sock_net(sk), skb);
1381}
1382
1383/*
1384 *      Throw away all pending data on the socket.
1385 */
1386static void __ip_flush_pending_frames(struct sock *sk,
1387                                      struct sk_buff_head *queue,
1388                                      struct inet_cork *cork)
1389{
1390        struct sk_buff *skb;
1391
1392        while ((skb = __skb_dequeue_tail(queue)) != NULL)
1393                kfree_skb(skb);
1394
1395        ip_cork_release(cork);
1396}
1397
1398void ip_flush_pending_frames(struct sock *sk)
1399{
1400        __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1401}
1402
1403struct sk_buff *ip_make_skb(struct sock *sk,
1404                            struct flowi4 *fl4,
1405                            int getfrag(void *from, char *to, int offset,
1406                                        int len, int odd, struct sk_buff *skb),
1407                            void *from, int length, int transhdrlen,
1408                            struct ipcm_cookie *ipc, struct rtable **rtp,
1409                            unsigned int flags)
1410{
1411        struct inet_cork cork;
1412        struct sk_buff_head queue;
1413        int err;
1414
1415        if (flags & MSG_PROBE)
1416                return NULL;
1417
1418        __skb_queue_head_init(&queue);
1419
1420        cork.flags = 0;
1421        cork.addr = 0;
1422        cork.opt = NULL;
1423        err = ip_setup_cork(sk, &cork, ipc, rtp);
1424        if (err)
1425                return ERR_PTR(err);
1426
1427        err = __ip_append_data(sk, fl4, &queue, &cork,
1428                               &current->task_frag, getfrag,
1429                               from, length, transhdrlen, flags);
1430        if (err) {
1431                __ip_flush_pending_frames(sk, &queue, &cork);
1432                return ERR_PTR(err);
1433        }
1434
1435        return __ip_make_skb(sk, fl4, &queue, &cork);
1436}
1437
1438/*
1439 *      Fetch data from kernel space and fill in checksum if needed.
1440 */
1441static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1442                              int len, int odd, struct sk_buff *skb)
1443{
1444        __wsum csum;
1445
1446        csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1447        skb->csum = csum_block_add(skb->csum, csum, odd);
1448        return 0;
1449}
1450
1451/*
1452 *      Generic function to send a packet as reply to another packet.
1453 *      Used to send some TCP resets/acks so far.
1454 *
1455 *      Use a fake percpu inet socket to avoid false sharing and contention.
1456 */
1457static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
1458        .sk = {
1459                .__sk_common = {
1460                        .skc_refcnt = ATOMIC_INIT(1),
1461                },
1462                .sk_wmem_alloc  = ATOMIC_INIT(1),
1463                .sk_allocation  = GFP_ATOMIC,
1464                .sk_flags       = (1UL << SOCK_USE_WRITE_QUEUE),
1465        },
1466        .pmtudisc       = IP_PMTUDISC_WANT,
1467        .uc_ttl         = -1,
1468};
1469
1470void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
1471                           __be32 saddr, const struct ip_reply_arg *arg,
1472                           unsigned int len)
1473{
1474        struct ip_options_data replyopts;
1475        struct ipcm_cookie ipc;
1476        struct flowi4 fl4;
1477        struct rtable *rt = skb_rtable(skb);
1478        struct sk_buff *nskb;
1479        struct sock *sk;
1480        struct inet_sock *inet;
1481
1482        if (ip_options_echo(&replyopts.opt.opt, skb))
1483                return;
1484
1485        ipc.addr = daddr;
1486        ipc.opt = NULL;
1487        ipc.tx_flags = 0;
1488
1489        if (replyopts.opt.opt.optlen) {
1490                ipc.opt = &replyopts.opt;
1491
1492                if (replyopts.opt.opt.srr)
1493                        daddr = replyopts.opt.opt.faddr;
1494        }
1495
1496        flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1497                           RT_TOS(arg->tos),
1498                           RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1499                           ip_reply_arg_flowi_flags(arg),
1500                           daddr, saddr,
1501                           tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1502        security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1503        rt = ip_route_output_key(net, &fl4);
1504        if (IS_ERR(rt))
1505                return;
1506
1507        inet = &get_cpu_var(unicast_sock);
1508
1509        inet->tos = arg->tos;
1510        sk = &inet->sk;
1511        sk->sk_priority = skb->priority;
1512        sk->sk_protocol = ip_hdr(skb)->protocol;
1513        sk->sk_bound_dev_if = arg->bound_dev_if;
1514        sock_net_set(sk, net);
1515        __skb_queue_head_init(&sk->sk_write_queue);
1516        sk->sk_sndbuf = sysctl_wmem_default;
1517        ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1518                       &ipc, &rt, MSG_DONTWAIT);
1519        nskb = skb_peek(&sk->sk_write_queue);
1520        if (nskb) {
1521                if (arg->csumoffset >= 0)
1522                        *((__sum16 *)skb_transport_header(nskb) +
1523                          arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1524                                                                arg->csum));
1525                nskb->ip_summed = CHECKSUM_NONE;
1526                skb_orphan(nskb);
1527                skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
1528                ip_push_pending_frames(sk, &fl4);
1529        }
1530
1531        put_cpu_var(unicast_sock);
1532
1533        ip_rt_put(rt);
1534}
1535
1536void __init ip_init(void)
1537{
1538        ip_rt_init();
1539        inet_initpeers();
1540
1541#if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1542        igmp_mc_proc_init();
1543#endif
1544}
1545
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