linux/net/ipv4/icmp.c
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   1/*
   2 *      NET3:   Implementation of the ICMP protocol layer.
   3 *
   4 *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
   5 *
   6 *      This program is free software; you can redistribute it and/or
   7 *      modify it under the terms of the GNU General Public License
   8 *      as published by the Free Software Foundation; either version
   9 *      2 of the License, or (at your option) any later version.
  10 *
  11 *      Some of the function names and the icmp unreach table for this
  12 *      module were derived from [icmp.c 1.0.11 06/02/93] by
  13 *      Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
  14 *      Other than that this module is a complete rewrite.
  15 *
  16 *      Fixes:
  17 *      Clemens Fruhwirth       :       introduce global icmp rate limiting
  18 *                                      with icmp type masking ability instead
  19 *                                      of broken per type icmp timeouts.
  20 *              Mike Shaver     :       RFC1122 checks.
  21 *              Alan Cox        :       Multicast ping reply as self.
  22 *              Alan Cox        :       Fix atomicity lockup in ip_build_xmit
  23 *                                      call.
  24 *              Alan Cox        :       Added 216,128 byte paths to the MTU
  25 *                                      code.
  26 *              Martin Mares    :       RFC1812 checks.
  27 *              Martin Mares    :       Can be configured to follow redirects
  28 *                                      if acting as a router _without_ a
  29 *                                      routing protocol (RFC 1812).
  30 *              Martin Mares    :       Echo requests may be configured to
  31 *                                      be ignored (RFC 1812).
  32 *              Martin Mares    :       Limitation of ICMP error message
  33 *                                      transmit rate (RFC 1812).
  34 *              Martin Mares    :       TOS and Precedence set correctly
  35 *                                      (RFC 1812).
  36 *              Martin Mares    :       Now copying as much data from the
  37 *                                      original packet as we can without
  38 *                                      exceeding 576 bytes (RFC 1812).
  39 *      Willy Konynenberg       :       Transparent proxying support.
  40 *              Keith Owens     :       RFC1191 correction for 4.2BSD based
  41 *                                      path MTU bug.
  42 *              Thomas Quinot   :       ICMP Dest Unreach codes up to 15 are
  43 *                                      valid (RFC 1812).
  44 *              Andi Kleen      :       Check all packet lengths properly
  45 *                                      and moved all kfree_skb() up to
  46 *                                      icmp_rcv.
  47 *              Andi Kleen      :       Move the rate limit bookkeeping
  48 *                                      into the dest entry and use a token
  49 *                                      bucket filter (thanks to ANK). Make
  50 *                                      the rates sysctl configurable.
  51 *              Yu Tianli       :       Fixed two ugly bugs in icmp_send
  52 *                                      - IP option length was accounted wrongly
  53 *                                      - ICMP header length was not accounted
  54 *                                        at all.
  55 *              Tristan Greaves :       Added sysctl option to ignore bogus
  56 *                                      broadcast responses from broken routers.
  57 *
  58 * To Fix:
  59 *
  60 *      - Should use skb_pull() instead of all the manual checking.
  61 *        This would also greatly simply some upper layer error handlers. --AK
  62 *
  63 */
  64
  65#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  66
  67#include <linux/module.h>
  68#include <linux/types.h>
  69#include <linux/jiffies.h>
  70#include <linux/kernel.h>
  71#include <linux/fcntl.h>
  72#include <linux/socket.h>
  73#include <linux/in.h>
  74#include <linux/inet.h>
  75#include <linux/inetdevice.h>
  76#include <linux/netdevice.h>
  77#include <linux/string.h>
  78#include <linux/netfilter_ipv4.h>
  79#include <linux/slab.h>
  80#include <net/snmp.h>
  81#include <net/ip.h>
  82#include <net/route.h>
  83#include <net/protocol.h>
  84#include <net/icmp.h>
  85#include <net/tcp.h>
  86#include <net/udp.h>
  87#include <net/raw.h>
  88#include <net/ping.h>
  89#include <linux/skbuff.h>
  90#include <net/sock.h>
  91#include <linux/errno.h>
  92#include <linux/timer.h>
  93#include <linux/init.h>
  94#include <asm/uaccess.h>
  95#include <net/checksum.h>
  96#include <net/xfrm.h>
  97#include <net/inet_common.h>
  98#include <net/ip_fib.h>
  99
 100/*
 101 *      Build xmit assembly blocks
 102 */
 103
 104struct icmp_bxm {
 105        struct sk_buff *skb;
 106        int offset;
 107        int data_len;
 108
 109        struct {
 110                struct icmphdr icmph;
 111                __be32         times[3];
 112        } data;
 113        int head_len;
 114        struct ip_options_data replyopts;
 115};
 116
 117/* An array of errno for error messages from dest unreach. */
 118/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
 119
 120const struct icmp_err icmp_err_convert[] = {
 121        {
 122                .errno = ENETUNREACH,   /* ICMP_NET_UNREACH */
 123                .fatal = 0,
 124        },
 125        {
 126                .errno = EHOSTUNREACH,  /* ICMP_HOST_UNREACH */
 127                .fatal = 0,
 128        },
 129        {
 130                .errno = ENOPROTOOPT    /* ICMP_PROT_UNREACH */,
 131                .fatal = 1,
 132        },
 133        {
 134                .errno = ECONNREFUSED,  /* ICMP_PORT_UNREACH */
 135                .fatal = 1,
 136        },
 137        {
 138                .errno = EMSGSIZE,      /* ICMP_FRAG_NEEDED */
 139                .fatal = 0,
 140        },
 141        {
 142                .errno = EOPNOTSUPP,    /* ICMP_SR_FAILED */
 143                .fatal = 0,
 144        },
 145        {
 146                .errno = ENETUNREACH,   /* ICMP_NET_UNKNOWN */
 147                .fatal = 1,
 148        },
 149        {
 150                .errno = EHOSTDOWN,     /* ICMP_HOST_UNKNOWN */
 151                .fatal = 1,
 152        },
 153        {
 154                .errno = ENONET,        /* ICMP_HOST_ISOLATED */
 155                .fatal = 1,
 156        },
 157        {
 158                .errno = ENETUNREACH,   /* ICMP_NET_ANO */
 159                .fatal = 1,
 160        },
 161        {
 162                .errno = EHOSTUNREACH,  /* ICMP_HOST_ANO */
 163                .fatal = 1,
 164        },
 165        {
 166                .errno = ENETUNREACH,   /* ICMP_NET_UNR_TOS */
 167                .fatal = 0,
 168        },
 169        {
 170                .errno = EHOSTUNREACH,  /* ICMP_HOST_UNR_TOS */
 171                .fatal = 0,
 172        },
 173        {
 174                .errno = EHOSTUNREACH,  /* ICMP_PKT_FILTERED */
 175                .fatal = 1,
 176        },
 177        {
 178                .errno = EHOSTUNREACH,  /* ICMP_PREC_VIOLATION */
 179                .fatal = 1,
 180        },
 181        {
 182                .errno = EHOSTUNREACH,  /* ICMP_PREC_CUTOFF */
 183                .fatal = 1,
 184        },
 185};
 186EXPORT_SYMBOL(icmp_err_convert);
 187
 188/*
 189 *      ICMP control array. This specifies what to do with each ICMP.
 190 */
 191
 192struct icmp_control {
 193        void (*handler)(struct sk_buff *skb);
 194        short   error;          /* This ICMP is classed as an error message */
 195};
 196
 197static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 198
 199/*
 200 *      The ICMP socket(s). This is the most convenient way to flow control
 201 *      our ICMP output as well as maintain a clean interface throughout
 202 *      all layers. All Socketless IP sends will soon be gone.
 203 *
 204 *      On SMP we have one ICMP socket per-cpu.
 205 */
 206static struct sock *icmp_sk(struct net *net)
 207{
 208        return net->ipv4.icmp_sk[smp_processor_id()];
 209}
 210
 211static inline struct sock *icmp_xmit_lock(struct net *net)
 212{
 213        struct sock *sk;
 214
 215        local_bh_disable();
 216
 217        sk = icmp_sk(net);
 218
 219        if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 220                /* This can happen if the output path signals a
 221                 * dst_link_failure() for an outgoing ICMP packet.
 222                 */
 223                local_bh_enable();
 224                return NULL;
 225        }
 226        return sk;
 227}
 228
 229static inline void icmp_xmit_unlock(struct sock *sk)
 230{
 231        spin_unlock_bh(&sk->sk_lock.slock);
 232}
 233
 234/*
 235 *      Send an ICMP frame.
 236 */
 237
 238static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 239                                      struct flowi4 *fl4, int type, int code)
 240{
 241        struct dst_entry *dst = &rt->dst;
 242        bool rc = true;
 243
 244        if (type > NR_ICMP_TYPES)
 245                goto out;
 246
 247        /* Don't limit PMTU discovery. */
 248        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 249                goto out;
 250
 251        /* No rate limit on loopback */
 252        if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 253                goto out;
 254
 255        /* Limit if icmp type is enabled in ratemask. */
 256        if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
 257                struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1);
 258                rc = inet_peer_xrlim_allow(peer,
 259                                           net->ipv4.sysctl_icmp_ratelimit);
 260                inet_putpeer(peer);
 261        }
 262out:
 263        return rc;
 264}
 265
 266/*
 267 *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 268 */
 269void icmp_out_count(struct net *net, unsigned char type)
 270{
 271        ICMPMSGOUT_INC_STATS(net, type);
 272        ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 273}
 274
 275/*
 276 *      Checksum each fragment, and on the first include the headers and final
 277 *      checksum.
 278 */
 279static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 280                          struct sk_buff *skb)
 281{
 282        struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
 283        __wsum csum;
 284
 285        csum = skb_copy_and_csum_bits(icmp_param->skb,
 286                                      icmp_param->offset + offset,
 287                                      to, len, 0);
 288
 289        skb->csum = csum_block_add(skb->csum, csum, odd);
 290        if (icmp_pointers[icmp_param->data.icmph.type].error)
 291                nf_ct_attach(skb, icmp_param->skb);
 292        return 0;
 293}
 294
 295static void icmp_push_reply(struct icmp_bxm *icmp_param,
 296                            struct flowi4 *fl4,
 297                            struct ipcm_cookie *ipc, struct rtable **rt)
 298{
 299        struct sock *sk;
 300        struct sk_buff *skb;
 301
 302        sk = icmp_sk(dev_net((*rt)->dst.dev));
 303        if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 304                           icmp_param->data_len+icmp_param->head_len,
 305                           icmp_param->head_len,
 306                           ipc, rt, MSG_DONTWAIT) < 0) {
 307                ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
 308                ip_flush_pending_frames(sk);
 309        } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 310                struct icmphdr *icmph = icmp_hdr(skb);
 311                __wsum csum = 0;
 312                struct sk_buff *skb1;
 313
 314                skb_queue_walk(&sk->sk_write_queue, skb1) {
 315                        csum = csum_add(csum, skb1->csum);
 316                }
 317                csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 318                                                 (char *)icmph,
 319                                                 icmp_param->head_len, csum);
 320                icmph->checksum = csum_fold(csum);
 321                skb->ip_summed = CHECKSUM_NONE;
 322                ip_push_pending_frames(sk, fl4);
 323        }
 324}
 325
 326/*
 327 *      Driving logic for building and sending ICMP messages.
 328 */
 329
 330static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 331{
 332        struct ipcm_cookie ipc;
 333        struct rtable *rt = skb_rtable(skb);
 334        struct net *net = dev_net(rt->dst.dev);
 335        struct flowi4 fl4;
 336        struct sock *sk;
 337        struct inet_sock *inet;
 338        __be32 daddr, saddr;
 339
 340        if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
 341                return;
 342
 343        sk = icmp_xmit_lock(net);
 344        if (sk == NULL)
 345                return;
 346        inet = inet_sk(sk);
 347
 348        icmp_param->data.icmph.checksum = 0;
 349
 350        inet->tos = ip_hdr(skb)->tos;
 351        daddr = ipc.addr = ip_hdr(skb)->saddr;
 352        saddr = fib_compute_spec_dst(skb);
 353        ipc.opt = NULL;
 354        ipc.tx_flags = 0;
 355        if (icmp_param->replyopts.opt.opt.optlen) {
 356                ipc.opt = &icmp_param->replyopts.opt;
 357                if (ipc.opt->opt.srr)
 358                        daddr = icmp_param->replyopts.opt.opt.faddr;
 359        }
 360        memset(&fl4, 0, sizeof(fl4));
 361        fl4.daddr = daddr;
 362        fl4.saddr = saddr;
 363        fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 364        fl4.flowi4_proto = IPPROTO_ICMP;
 365        security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 366        rt = ip_route_output_key(net, &fl4);
 367        if (IS_ERR(rt))
 368                goto out_unlock;
 369        if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
 370                               icmp_param->data.icmph.code))
 371                icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 372        ip_rt_put(rt);
 373out_unlock:
 374        icmp_xmit_unlock(sk);
 375}
 376
 377static struct rtable *icmp_route_lookup(struct net *net,
 378                                        struct flowi4 *fl4,
 379                                        struct sk_buff *skb_in,
 380                                        const struct iphdr *iph,
 381                                        __be32 saddr, u8 tos,
 382                                        int type, int code,
 383                                        struct icmp_bxm *param)
 384{
 385        struct rtable *rt, *rt2;
 386        struct flowi4 fl4_dec;
 387        int err;
 388
 389        memset(fl4, 0, sizeof(*fl4));
 390        fl4->daddr = (param->replyopts.opt.opt.srr ?
 391                      param->replyopts.opt.opt.faddr : iph->saddr);
 392        fl4->saddr = saddr;
 393        fl4->flowi4_tos = RT_TOS(tos);
 394        fl4->flowi4_proto = IPPROTO_ICMP;
 395        fl4->fl4_icmp_type = type;
 396        fl4->fl4_icmp_code = code;
 397        security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
 398        rt = __ip_route_output_key(net, fl4);
 399        if (IS_ERR(rt))
 400                return rt;
 401
 402        /* No need to clone since we're just using its address. */
 403        rt2 = rt;
 404
 405        rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 406                                           flowi4_to_flowi(fl4), NULL, 0);
 407        if (!IS_ERR(rt)) {
 408                if (rt != rt2)
 409                        return rt;
 410        } else if (PTR_ERR(rt) == -EPERM) {
 411                rt = NULL;
 412        } else
 413                return rt;
 414
 415        err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 416        if (err)
 417                goto relookup_failed;
 418
 419        if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
 420                rt2 = __ip_route_output_key(net, &fl4_dec);
 421                if (IS_ERR(rt2))
 422                        err = PTR_ERR(rt2);
 423        } else {
 424                struct flowi4 fl4_2 = {};
 425                unsigned long orefdst;
 426
 427                fl4_2.daddr = fl4_dec.saddr;
 428                rt2 = ip_route_output_key(net, &fl4_2);
 429                if (IS_ERR(rt2)) {
 430                        err = PTR_ERR(rt2);
 431                        goto relookup_failed;
 432                }
 433                /* Ugh! */
 434                orefdst = skb_in->_skb_refdst; /* save old refdst */
 435                err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 436                                     RT_TOS(tos), rt2->dst.dev);
 437
 438                dst_release(&rt2->dst);
 439                rt2 = skb_rtable(skb_in);
 440                skb_in->_skb_refdst = orefdst; /* restore old refdst */
 441        }
 442
 443        if (err)
 444                goto relookup_failed;
 445
 446        rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 447                                            flowi4_to_flowi(&fl4_dec), NULL,
 448                                            XFRM_LOOKUP_ICMP);
 449        if (!IS_ERR(rt2)) {
 450                dst_release(&rt->dst);
 451                memcpy(fl4, &fl4_dec, sizeof(*fl4));
 452                rt = rt2;
 453        } else if (PTR_ERR(rt2) == -EPERM) {
 454                if (rt)
 455                        dst_release(&rt->dst);
 456                return rt2;
 457        } else {
 458                err = PTR_ERR(rt2);
 459                goto relookup_failed;
 460        }
 461        return rt;
 462
 463relookup_failed:
 464        if (rt)
 465                return rt;
 466        return ERR_PTR(err);
 467}
 468
 469/*
 470 *      Send an ICMP message in response to a situation
 471 *
 472 *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 473 *                MAY send more (we do).
 474 *                      MUST NOT change this header information.
 475 *                      MUST NOT reply to a multicast/broadcast IP address.
 476 *                      MUST NOT reply to a multicast/broadcast MAC address.
 477 *                      MUST reply to only the first fragment.
 478 */
 479
 480void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 481{
 482        struct iphdr *iph;
 483        int room;
 484        struct icmp_bxm icmp_param;
 485        struct rtable *rt = skb_rtable(skb_in);
 486        struct ipcm_cookie ipc;
 487        struct flowi4 fl4;
 488        __be32 saddr;
 489        u8  tos;
 490        struct net *net;
 491        struct sock *sk;
 492
 493        if (!rt)
 494                goto out;
 495        net = dev_net(rt->dst.dev);
 496
 497        /*
 498         *      Find the original header. It is expected to be valid, of course.
 499         *      Check this, icmp_send is called from the most obscure devices
 500         *      sometimes.
 501         */
 502        iph = ip_hdr(skb_in);
 503
 504        if ((u8 *)iph < skb_in->head ||
 505            (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
 506                goto out;
 507
 508        /*
 509         *      No replies to physical multicast/broadcast
 510         */
 511        if (skb_in->pkt_type != PACKET_HOST)
 512                goto out;
 513
 514        /*
 515         *      Now check at the protocol level
 516         */
 517        if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 518                goto out;
 519
 520        /*
 521         *      Only reply to fragment 0. We byte re-order the constant
 522         *      mask for efficiency.
 523         */
 524        if (iph->frag_off & htons(IP_OFFSET))
 525                goto out;
 526
 527        /*
 528         *      If we send an ICMP error to an ICMP error a mess would result..
 529         */
 530        if (icmp_pointers[type].error) {
 531                /*
 532                 *      We are an error, check if we are replying to an
 533                 *      ICMP error
 534                 */
 535                if (iph->protocol == IPPROTO_ICMP) {
 536                        u8 _inner_type, *itp;
 537
 538                        itp = skb_header_pointer(skb_in,
 539                                                 skb_network_header(skb_in) +
 540                                                 (iph->ihl << 2) +
 541                                                 offsetof(struct icmphdr,
 542                                                          type) -
 543                                                 skb_in->data,
 544                                                 sizeof(_inner_type),
 545                                                 &_inner_type);
 546                        if (itp == NULL)
 547                                goto out;
 548
 549                        /*
 550                         *      Assume any unknown ICMP type is an error. This
 551                         *      isn't specified by the RFC, but think about it..
 552                         */
 553                        if (*itp > NR_ICMP_TYPES ||
 554                            icmp_pointers[*itp].error)
 555                                goto out;
 556                }
 557        }
 558
 559        sk = icmp_xmit_lock(net);
 560        if (sk == NULL)
 561                return;
 562
 563        /*
 564         *      Construct source address and options.
 565         */
 566
 567        saddr = iph->daddr;
 568        if (!(rt->rt_flags & RTCF_LOCAL)) {
 569                struct net_device *dev = NULL;
 570
 571                rcu_read_lock();
 572                if (rt_is_input_route(rt) &&
 573                    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 574                        dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 575
 576                if (dev)
 577                        saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
 578                else
 579                        saddr = 0;
 580                rcu_read_unlock();
 581        }
 582
 583        tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
 584                                           IPTOS_PREC_INTERNETCONTROL) :
 585                                          iph->tos;
 586
 587        if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in))
 588                goto out_unlock;
 589
 590
 591        /*
 592         *      Prepare data for ICMP header.
 593         */
 594
 595        icmp_param.data.icmph.type       = type;
 596        icmp_param.data.icmph.code       = code;
 597        icmp_param.data.icmph.un.gateway = info;
 598        icmp_param.data.icmph.checksum   = 0;
 599        icmp_param.skb    = skb_in;
 600        icmp_param.offset = skb_network_offset(skb_in);
 601        inet_sk(sk)->tos = tos;
 602        ipc.addr = iph->saddr;
 603        ipc.opt = &icmp_param.replyopts.opt;
 604        ipc.tx_flags = 0;
 605
 606        rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
 607                               type, code, &icmp_param);
 608        if (IS_ERR(rt))
 609                goto out_unlock;
 610
 611        if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 612                goto ende;
 613
 614        /* RFC says return as much as we can without exceeding 576 bytes. */
 615
 616        room = dst_mtu(&rt->dst);
 617        if (room > 576)
 618                room = 576;
 619        room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 620        room -= sizeof(struct icmphdr);
 621
 622        icmp_param.data_len = skb_in->len - icmp_param.offset;
 623        if (icmp_param.data_len > room)
 624                icmp_param.data_len = room;
 625        icmp_param.head_len = sizeof(struct icmphdr);
 626
 627        icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
 628ende:
 629        ip_rt_put(rt);
 630out_unlock:
 631        icmp_xmit_unlock(sk);
 632out:;
 633}
 634EXPORT_SYMBOL(icmp_send);
 635
 636
 637static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 638{
 639        const struct iphdr *iph = (const struct iphdr *) skb->data;
 640        const struct net_protocol *ipprot;
 641        int protocol = iph->protocol;
 642
 643        /* Checkin full IP header plus 8 bytes of protocol to
 644         * avoid additional coding at protocol handlers.
 645         */
 646        if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
 647                return;
 648
 649        raw_icmp_error(skb, protocol, info);
 650
 651        rcu_read_lock();
 652        ipprot = rcu_dereference(inet_protos[protocol]);
 653        if (ipprot && ipprot->err_handler)
 654                ipprot->err_handler(skb, info);
 655        rcu_read_unlock();
 656}
 657
 658/*
 659 *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
 660 */
 661
 662static void icmp_unreach(struct sk_buff *skb)
 663{
 664        const struct iphdr *iph;
 665        struct icmphdr *icmph;
 666        struct net *net;
 667        u32 info = 0;
 668
 669        net = dev_net(skb_dst(skb)->dev);
 670
 671        /*
 672         *      Incomplete header ?
 673         *      Only checks for the IP header, there should be an
 674         *      additional check for longer headers in upper levels.
 675         */
 676
 677        if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 678                goto out_err;
 679
 680        icmph = icmp_hdr(skb);
 681        iph   = (const struct iphdr *)skb->data;
 682
 683        if (iph->ihl < 5) /* Mangled header, drop. */
 684                goto out_err;
 685
 686        if (icmph->type == ICMP_DEST_UNREACH) {
 687                switch (icmph->code & 15) {
 688                case ICMP_NET_UNREACH:
 689                case ICMP_HOST_UNREACH:
 690                case ICMP_PROT_UNREACH:
 691                case ICMP_PORT_UNREACH:
 692                        break;
 693                case ICMP_FRAG_NEEDED:
 694                        if (ipv4_config.no_pmtu_disc) {
 695                                LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
 696                                               &iph->daddr);
 697                        } else {
 698                                info = ntohs(icmph->un.frag.mtu);
 699                                if (!info)
 700                                        goto out;
 701                        }
 702                        break;
 703                case ICMP_SR_FAILED:
 704                        LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
 705                                       &iph->daddr);
 706                        break;
 707                default:
 708                        break;
 709                }
 710                if (icmph->code > NR_ICMP_UNREACH)
 711                        goto out;
 712        } else if (icmph->type == ICMP_PARAMETERPROB)
 713                info = ntohl(icmph->un.gateway) >> 24;
 714
 715        /*
 716         *      Throw it at our lower layers
 717         *
 718         *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 719         *                header.
 720         *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 721         *                transport layer.
 722         *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 723         *                transport layer.
 724         */
 725
 726        /*
 727         *      Check the other end isn't violating RFC 1122. Some routers send
 728         *      bogus responses to broadcast frames. If you see this message
 729         *      first check your netmask matches at both ends, if it does then
 730         *      get the other vendor to fix their kit.
 731         */
 732
 733        if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 734            inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
 735                net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 736                                     &ip_hdr(skb)->saddr,
 737                                     icmph->type, icmph->code,
 738                                     &iph->daddr, skb->dev->name);
 739                goto out;
 740        }
 741
 742        icmp_socket_deliver(skb, info);
 743
 744out:
 745        return;
 746out_err:
 747        ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 748        goto out;
 749}
 750
 751
 752/*
 753 *      Handle ICMP_REDIRECT.
 754 */
 755
 756static void icmp_redirect(struct sk_buff *skb)
 757{
 758        if (skb->len < sizeof(struct iphdr)) {
 759                ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
 760                return;
 761        }
 762
 763        if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 764                return;
 765
 766        icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
 767}
 768
 769/*
 770 *      Handle ICMP_ECHO ("ping") requests.
 771 *
 772 *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 773 *                requests.
 774 *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 775 *                included in the reply.
 776 *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 777 *                echo requests, MUST have default=NOT.
 778 *      See also WRT handling of options once they are done and working.
 779 */
 780
 781static void icmp_echo(struct sk_buff *skb)
 782{
 783        struct net *net;
 784
 785        net = dev_net(skb_dst(skb)->dev);
 786        if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 787                struct icmp_bxm icmp_param;
 788
 789                icmp_param.data.icmph      = *icmp_hdr(skb);
 790                icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 791                icmp_param.skb             = skb;
 792                icmp_param.offset          = 0;
 793                icmp_param.data_len        = skb->len;
 794                icmp_param.head_len        = sizeof(struct icmphdr);
 795                icmp_reply(&icmp_param, skb);
 796        }
 797}
 798
 799/*
 800 *      Handle ICMP Timestamp requests.
 801 *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
 802 *                SHOULD be in the kernel for minimum random latency.
 803 *                MUST be accurate to a few minutes.
 804 *                MUST be updated at least at 15Hz.
 805 */
 806static void icmp_timestamp(struct sk_buff *skb)
 807{
 808        struct timespec tv;
 809        struct icmp_bxm icmp_param;
 810        /*
 811         *      Too short.
 812         */
 813        if (skb->len < 4)
 814                goto out_err;
 815
 816        /*
 817         *      Fill in the current time as ms since midnight UT:
 818         */
 819        getnstimeofday(&tv);
 820        icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
 821                                         tv.tv_nsec / NSEC_PER_MSEC);
 822        icmp_param.data.times[2] = icmp_param.data.times[1];
 823        if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
 824                BUG();
 825        icmp_param.data.icmph      = *icmp_hdr(skb);
 826        icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
 827        icmp_param.data.icmph.code = 0;
 828        icmp_param.skb             = skb;
 829        icmp_param.offset          = 0;
 830        icmp_param.data_len        = 0;
 831        icmp_param.head_len        = sizeof(struct icmphdr) + 12;
 832        icmp_reply(&icmp_param, skb);
 833out:
 834        return;
 835out_err:
 836        ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 837        goto out;
 838}
 839
 840static void icmp_discard(struct sk_buff *skb)
 841{
 842}
 843
 844/*
 845 *      Deal with incoming ICMP packets.
 846 */
 847int icmp_rcv(struct sk_buff *skb)
 848{
 849        struct icmphdr *icmph;
 850        struct rtable *rt = skb_rtable(skb);
 851        struct net *net = dev_net(rt->dst.dev);
 852
 853        if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 854                struct sec_path *sp = skb_sec_path(skb);
 855                int nh;
 856
 857                if (!(sp && sp->xvec[sp->len - 1]->props.flags &
 858                                 XFRM_STATE_ICMP))
 859                        goto drop;
 860
 861                if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
 862                        goto drop;
 863
 864                nh = skb_network_offset(skb);
 865                skb_set_network_header(skb, sizeof(*icmph));
 866
 867                if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
 868                        goto drop;
 869
 870                skb_set_network_header(skb, nh);
 871        }
 872
 873        ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
 874
 875        switch (skb->ip_summed) {
 876        case CHECKSUM_COMPLETE:
 877                if (!csum_fold(skb->csum))
 878                        break;
 879                /* fall through */
 880        case CHECKSUM_NONE:
 881                skb->csum = 0;
 882                if (__skb_checksum_complete(skb))
 883                        goto error;
 884        }
 885
 886        if (!pskb_pull(skb, sizeof(*icmph)))
 887                goto error;
 888
 889        icmph = icmp_hdr(skb);
 890
 891        ICMPMSGIN_INC_STATS_BH(net, icmph->type);
 892        /*
 893         *      18 is the highest 'known' ICMP type. Anything else is a mystery
 894         *
 895         *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 896         *                discarded.
 897         */
 898        if (icmph->type > NR_ICMP_TYPES)
 899                goto error;
 900
 901
 902        /*
 903         *      Parse the ICMP message
 904         */
 905
 906        if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
 907                /*
 908                 *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
 909                 *        silently ignored (we let user decide with a sysctl).
 910                 *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
 911                 *        discarded if to broadcast/multicast.
 912                 */
 913                if ((icmph->type == ICMP_ECHO ||
 914                     icmph->type == ICMP_TIMESTAMP) &&
 915                    net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
 916                        goto error;
 917                }
 918                if (icmph->type != ICMP_ECHO &&
 919                    icmph->type != ICMP_TIMESTAMP &&
 920                    icmph->type != ICMP_ADDRESS &&
 921                    icmph->type != ICMP_ADDRESSREPLY) {
 922                        goto error;
 923                }
 924        }
 925
 926        icmp_pointers[icmph->type].handler(skb);
 927
 928drop:
 929        kfree_skb(skb);
 930        return 0;
 931error:
 932        ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 933        goto drop;
 934}
 935
 936/*
 937 *      This table is the definition of how we handle ICMP.
 938 */
 939static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
 940        [ICMP_ECHOREPLY] = {
 941                .handler = ping_rcv,
 942        },
 943        [1] = {
 944                .handler = icmp_discard,
 945                .error = 1,
 946        },
 947        [2] = {
 948                .handler = icmp_discard,
 949                .error = 1,
 950        },
 951        [ICMP_DEST_UNREACH] = {
 952                .handler = icmp_unreach,
 953                .error = 1,
 954        },
 955        [ICMP_SOURCE_QUENCH] = {
 956                .handler = icmp_unreach,
 957                .error = 1,
 958        },
 959        [ICMP_REDIRECT] = {
 960                .handler = icmp_redirect,
 961                .error = 1,
 962        },
 963        [6] = {
 964                .handler = icmp_discard,
 965                .error = 1,
 966        },
 967        [7] = {
 968                .handler = icmp_discard,
 969                .error = 1,
 970        },
 971        [ICMP_ECHO] = {
 972                .handler = icmp_echo,
 973        },
 974        [9] = {
 975                .handler = icmp_discard,
 976                .error = 1,
 977        },
 978        [10] = {
 979                .handler = icmp_discard,
 980                .error = 1,
 981        },
 982        [ICMP_TIME_EXCEEDED] = {
 983                .handler = icmp_unreach,
 984                .error = 1,
 985        },
 986        [ICMP_PARAMETERPROB] = {
 987                .handler = icmp_unreach,
 988                .error = 1,
 989        },
 990        [ICMP_TIMESTAMP] = {
 991                .handler = icmp_timestamp,
 992        },
 993        [ICMP_TIMESTAMPREPLY] = {
 994                .handler = icmp_discard,
 995        },
 996        [ICMP_INFO_REQUEST] = {
 997                .handler = icmp_discard,
 998        },
 999        [ICMP_INFO_REPLY] = {
1000                .handler = icmp_discard,
1001        },
1002        [ICMP_ADDRESS] = {
1003                .handler = icmp_discard,
1004        },
1005        [ICMP_ADDRESSREPLY] = {
1006                .handler = icmp_discard,
1007        },
1008};
1009
1010static void __net_exit icmp_sk_exit(struct net *net)
1011{
1012        int i;
1013
1014        for_each_possible_cpu(i)
1015                inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1016        kfree(net->ipv4.icmp_sk);
1017        net->ipv4.icmp_sk = NULL;
1018}
1019
1020static int __net_init icmp_sk_init(struct net *net)
1021{
1022        int i, err;
1023
1024        net->ipv4.icmp_sk =
1025                kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1026        if (net->ipv4.icmp_sk == NULL)
1027                return -ENOMEM;
1028
1029        for_each_possible_cpu(i) {
1030                struct sock *sk;
1031
1032                err = inet_ctl_sock_create(&sk, PF_INET,
1033                                           SOCK_RAW, IPPROTO_ICMP, net);
1034                if (err < 0)
1035                        goto fail;
1036
1037                net->ipv4.icmp_sk[i] = sk;
1038
1039                /* Enough space for 2 64K ICMP packets, including
1040                 * sk_buff/skb_shared_info struct overhead.
1041                 */
1042                sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1043
1044                /*
1045                 * Speedup sock_wfree()
1046                 */
1047                sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1048                inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1049        }
1050
1051        /* Control parameters for ECHO replies. */
1052        net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1053        net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1054
1055        /* Control parameter - ignore bogus broadcast responses? */
1056        net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1057
1058        /*
1059         *      Configurable global rate limit.
1060         *
1061         *      ratelimit defines tokens/packet consumed for dst->rate_token
1062         *      bucket ratemask defines which icmp types are ratelimited by
1063         *      setting it's bit position.
1064         *
1065         *      default:
1066         *      dest unreachable (3), source quench (4),
1067         *      time exceeded (11), parameter problem (12)
1068         */
1069
1070        net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1071        net->ipv4.sysctl_icmp_ratemask = 0x1818;
1072        net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1073
1074        return 0;
1075
1076fail:
1077        for_each_possible_cpu(i)
1078                inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1079        kfree(net->ipv4.icmp_sk);
1080        return err;
1081}
1082
1083static struct pernet_operations __net_initdata icmp_sk_ops = {
1084       .init = icmp_sk_init,
1085       .exit = icmp_sk_exit,
1086};
1087
1088int __init icmp_init(void)
1089{
1090        return register_pernet_subsys(&icmp_sk_ops);
1091}
1092
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