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                if (peer)
 261                        inet_putpeer(peer);
 262        }
 263out:
 264        return rc;
 265}
 266
 267/*
 268 *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 269 */
 270void icmp_out_count(struct net *net, unsigned char type)
 271{
 272        ICMPMSGOUT_INC_STATS(net, type);
 273        ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 274}
 275
 276/*
 277 *      Checksum each fragment, and on the first include the headers and final
 278 *      checksum.
 279 */
 280static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 281                          struct sk_buff *skb)
 282{
 283        struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
 284        __wsum csum;
 285
 286        csum = skb_copy_and_csum_bits(icmp_param->skb,
 287                                      icmp_param->offset + offset,
 288                                      to, len, 0);
 289
 290        skb->csum = csum_block_add(skb->csum, csum, odd);
 291        if (icmp_pointers[icmp_param->data.icmph.type].error)
 292                nf_ct_attach(skb, icmp_param->skb);
 293        return 0;
 294}
 295
 296static void icmp_push_reply(struct icmp_bxm *icmp_param,
 297                            struct flowi4 *fl4,
 298                            struct ipcm_cookie *ipc, struct rtable **rt)
 299{
 300        struct sock *sk;
 301        struct sk_buff *skb;
 302
 303        sk = icmp_sk(dev_net((*rt)->dst.dev));
 304        if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 305                           icmp_param->data_len+icmp_param->head_len,
 306                           icmp_param->head_len,
 307                           ipc, rt, MSG_DONTWAIT) < 0) {
 308                ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
 309                ip_flush_pending_frames(sk);
 310        } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 311                struct icmphdr *icmph = icmp_hdr(skb);
 312                __wsum csum = 0;
 313                struct sk_buff *skb1;
 314
 315                skb_queue_walk(&sk->sk_write_queue, skb1) {
 316                        csum = csum_add(csum, skb1->csum);
 317                }
 318                csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 319                                                 (char *)icmph,
 320                                                 icmp_param->head_len, csum);
 321                icmph->checksum = csum_fold(csum);
 322                skb->ip_summed = CHECKSUM_NONE;
 323                ip_push_pending_frames(sk, fl4);
 324        }
 325}
 326
 327/*
 328 *      Driving logic for building and sending ICMP messages.
 329 */
 330
 331static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 332{
 333        struct ipcm_cookie ipc;
 334        struct rtable *rt = skb_rtable(skb);
 335        struct net *net = dev_net(rt->dst.dev);
 336        struct flowi4 fl4;
 337        struct sock *sk;
 338        struct inet_sock *inet;
 339        __be32 daddr, saddr;
 340
 341        if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
 342                return;
 343
 344        sk = icmp_xmit_lock(net);
 345        if (sk == NULL)
 346                return;
 347        inet = inet_sk(sk);
 348
 349        icmp_param->data.icmph.checksum = 0;
 350
 351        inet->tos = ip_hdr(skb)->tos;
 352        daddr = ipc.addr = ip_hdr(skb)->saddr;
 353        saddr = fib_compute_spec_dst(skb);
 354        ipc.opt = NULL;
 355        ipc.tx_flags = 0;
 356        if (icmp_param->replyopts.opt.opt.optlen) {
 357                ipc.opt = &icmp_param->replyopts.opt;
 358                if (ipc.opt->opt.srr)
 359                        daddr = icmp_param->replyopts.opt.opt.faddr;
 360        }
 361        memset(&fl4, 0, sizeof(fl4));
 362        fl4.daddr = daddr;
 363        fl4.saddr = saddr;
 364        fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 365        fl4.flowi4_proto = IPPROTO_ICMP;
 366        security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 367        rt = ip_route_output_key(net, &fl4);
 368        if (IS_ERR(rt))
 369                goto out_unlock;
 370        if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
 371                               icmp_param->data.icmph.code))
 372                icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 373        ip_rt_put(rt);
 374out_unlock:
 375        icmp_xmit_unlock(sk);
 376}
 377
 378static struct rtable *icmp_route_lookup(struct net *net,
 379                                        struct flowi4 *fl4,
 380                                        struct sk_buff *skb_in,
 381                                        const struct iphdr *iph,
 382                                        __be32 saddr, u8 tos,
 383                                        int type, int code,
 384                                        struct icmp_bxm *param)
 385{
 386        struct rtable *rt, *rt2;
 387        struct flowi4 fl4_dec;
 388        int err;
 389
 390        memset(fl4, 0, sizeof(*fl4));
 391        fl4->daddr = (param->replyopts.opt.opt.srr ?
 392                      param->replyopts.opt.opt.faddr : iph->saddr);
 393        fl4->saddr = saddr;
 394        fl4->flowi4_tos = RT_TOS(tos);
 395        fl4->flowi4_proto = IPPROTO_ICMP;
 396        fl4->fl4_icmp_type = type;
 397        fl4->fl4_icmp_code = code;
 398        security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
 399        rt = __ip_route_output_key(net, fl4);
 400        if (IS_ERR(rt))
 401                return rt;
 402
 403        /* No need to clone since we're just using its address. */
 404        rt2 = rt;
 405
 406        rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 407                                           flowi4_to_flowi(fl4), NULL, 0);
 408        if (!IS_ERR(rt)) {
 409                if (rt != rt2)
 410                        return rt;
 411        } else if (PTR_ERR(rt) == -EPERM) {
 412                rt = NULL;
 413        } else
 414                return rt;
 415
 416        err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 417        if (err)
 418                goto relookup_failed;
 419
 420        if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
 421                rt2 = __ip_route_output_key(net, &fl4_dec);
 422                if (IS_ERR(rt2))
 423                        err = PTR_ERR(rt2);
 424        } else {
 425                struct flowi4 fl4_2 = {};
 426                unsigned long orefdst;
 427
 428                fl4_2.daddr = fl4_dec.saddr;
 429                rt2 = ip_route_output_key(net, &fl4_2);
 430                if (IS_ERR(rt2)) {
 431                        err = PTR_ERR(rt2);
 432                        goto relookup_failed;
 433                }
 434                /* Ugh! */
 435                orefdst = skb_in->_skb_refdst; /* save old refdst */
 436                err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 437                                     RT_TOS(tos), rt2->dst.dev);
 438
 439                dst_release(&rt2->dst);
 440                rt2 = skb_rtable(skb_in);
 441                skb_in->_skb_refdst = orefdst; /* restore old refdst */
 442        }
 443
 444        if (err)
 445                goto relookup_failed;
 446
 447        rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 448                                            flowi4_to_flowi(&fl4_dec), NULL,
 449                                            XFRM_LOOKUP_ICMP);
 450        if (!IS_ERR(rt2)) {
 451                dst_release(&rt->dst);
 452                memcpy(fl4, &fl4_dec, sizeof(*fl4));
 453                rt = rt2;
 454        } else if (PTR_ERR(rt2) == -EPERM) {
 455                if (rt)
 456                        dst_release(&rt->dst);
 457                return rt2;
 458        } else {
 459                err = PTR_ERR(rt2);
 460                goto relookup_failed;
 461        }
 462        return rt;
 463
 464relookup_failed:
 465        if (rt)
 466                return rt;
 467        return ERR_PTR(err);
 468}
 469
 470/*
 471 *      Send an ICMP message in response to a situation
 472 *
 473 *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 474 *                MAY send more (we do).
 475 *                      MUST NOT change this header information.
 476 *                      MUST NOT reply to a multicast/broadcast IP address.
 477 *                      MUST NOT reply to a multicast/broadcast MAC address.
 478 *                      MUST reply to only the first fragment.
 479 */
 480
 481void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 482{
 483        struct iphdr *iph;
 484        int room;
 485        struct icmp_bxm icmp_param;
 486        struct rtable *rt = skb_rtable(skb_in);
 487        struct ipcm_cookie ipc;
 488        struct flowi4 fl4;
 489        __be32 saddr;
 490        u8  tos;
 491        struct net *net;
 492        struct sock *sk;
 493
 494        if (!rt)
 495                goto out;
 496        net = dev_net(rt->dst.dev);
 497
 498        /*
 499         *      Find the original header. It is expected to be valid, of course.
 500         *      Check this, icmp_send is called from the most obscure devices
 501         *      sometimes.
 502         */
 503        iph = ip_hdr(skb_in);
 504
 505        if ((u8 *)iph < skb_in->head ||
 506            (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
 507                goto out;
 508
 509        /*
 510         *      No replies to physical multicast/broadcast
 511         */
 512        if (skb_in->pkt_type != PACKET_HOST)
 513                goto out;
 514
 515        /*
 516         *      Now check at the protocol level
 517         */
 518        if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 519                goto out;
 520
 521        /*
 522         *      Only reply to fragment 0. We byte re-order the constant
 523         *      mask for efficiency.
 524         */
 525        if (iph->frag_off & htons(IP_OFFSET))
 526                goto out;
 527
 528        /*
 529         *      If we send an ICMP error to an ICMP error a mess would result..
 530         */
 531        if (icmp_pointers[type].error) {
 532                /*
 533                 *      We are an error, check if we are replying to an
 534                 *      ICMP error
 535                 */
 536                if (iph->protocol == IPPROTO_ICMP) {
 537                        u8 _inner_type, *itp;
 538
 539                        itp = skb_header_pointer(skb_in,
 540                                                 skb_network_header(skb_in) +
 541                                                 (iph->ihl << 2) +
 542                                                 offsetof(struct icmphdr,
 543                                                          type) -
 544                                                 skb_in->data,
 545                                                 sizeof(_inner_type),
 546                                                 &_inner_type);
 547                        if (itp == NULL)
 548                                goto out;
 549
 550                        /*
 551                         *      Assume any unknown ICMP type is an error. This
 552                         *      isn't specified by the RFC, but think about it..
 553                         */
 554                        if (*itp > NR_ICMP_TYPES ||
 555                            icmp_pointers[*itp].error)
 556                                goto out;
 557                }
 558        }
 559
 560        sk = icmp_xmit_lock(net);
 561        if (sk == NULL)
 562                return;
 563
 564        /*
 565         *      Construct source address and options.
 566         */
 567
 568        saddr = iph->daddr;
 569        if (!(rt->rt_flags & RTCF_LOCAL)) {
 570                struct net_device *dev = NULL;
 571
 572                rcu_read_lock();
 573                if (rt_is_input_route(rt) &&
 574                    net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 575                        dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 576
 577                if (dev)
 578                        saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
 579                else
 580                        saddr = 0;
 581                rcu_read_unlock();
 582        }
 583
 584        tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
 585                                           IPTOS_PREC_INTERNETCONTROL) :
 586                                          iph->tos;
 587
 588        if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in))
 589                goto out_unlock;
 590
 591
 592        /*
 593         *      Prepare data for ICMP header.
 594         */
 595
 596        icmp_param.data.icmph.type       = type;
 597        icmp_param.data.icmph.code       = code;
 598        icmp_param.data.icmph.un.gateway = info;
 599        icmp_param.data.icmph.checksum   = 0;
 600        icmp_param.skb    = skb_in;
 601        icmp_param.offset = skb_network_offset(skb_in);
 602        inet_sk(sk)->tos = tos;
 603        ipc.addr = iph->saddr;
 604        ipc.opt = &icmp_param.replyopts.opt;
 605        ipc.tx_flags = 0;
 606
 607        rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
 608                               type, code, &icmp_param);
 609        if (IS_ERR(rt))
 610                goto out_unlock;
 611
 612        if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 613                goto ende;
 614
 615        /* RFC says return as much as we can without exceeding 576 bytes. */
 616
 617        room = dst_mtu(&rt->dst);
 618        if (room > 576)
 619                room = 576;
 620        room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 621        room -= sizeof(struct icmphdr);
 622
 623        icmp_param.data_len = skb_in->len - icmp_param.offset;
 624        if (icmp_param.data_len > room)
 625                icmp_param.data_len = room;
 626        icmp_param.head_len = sizeof(struct icmphdr);
 627
 628        icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
 629ende:
 630        ip_rt_put(rt);
 631out_unlock:
 632        icmp_xmit_unlock(sk);
 633out:;
 634}
 635EXPORT_SYMBOL(icmp_send);
 636
 637
 638static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 639{
 640        const struct iphdr *iph = (const struct iphdr *) skb->data;
 641        const struct net_protocol *ipprot;
 642        int protocol = iph->protocol;
 643
 644        /* Checkin full IP header plus 8 bytes of protocol to
 645         * avoid additional coding at protocol handlers.
 646         */
 647        if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
 648                return;
 649
 650        raw_icmp_error(skb, protocol, info);
 651
 652        rcu_read_lock();
 653        ipprot = rcu_dereference(inet_protos[protocol]);
 654        if (ipprot && ipprot->err_handler)
 655                ipprot->err_handler(skb, info);
 656        rcu_read_unlock();
 657}
 658
 659/*
 660 *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
 661 */
 662
 663static void icmp_unreach(struct sk_buff *skb)
 664{
 665        const struct iphdr *iph;
 666        struct icmphdr *icmph;
 667        struct net *net;
 668        u32 info = 0;
 669
 670        net = dev_net(skb_dst(skb)->dev);
 671
 672        /*
 673         *      Incomplete header ?
 674         *      Only checks for the IP header, there should be an
 675         *      additional check for longer headers in upper levels.
 676         */
 677
 678        if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 679                goto out_err;
 680
 681        icmph = icmp_hdr(skb);
 682        iph   = (const struct iphdr *)skb->data;
 683
 684        if (iph->ihl < 5) /* Mangled header, drop. */
 685                goto out_err;
 686
 687        if (icmph->type == ICMP_DEST_UNREACH) {
 688                switch (icmph->code & 15) {
 689                case ICMP_NET_UNREACH:
 690                case ICMP_HOST_UNREACH:
 691                case ICMP_PROT_UNREACH:
 692                case ICMP_PORT_UNREACH:
 693                        break;
 694                case ICMP_FRAG_NEEDED:
 695                        if (ipv4_config.no_pmtu_disc) {
 696                                LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
 697                                               &iph->daddr);
 698                        } else {
 699                                info = ntohs(icmph->un.frag.mtu);
 700                                if (!info)
 701                                        goto out;
 702                        }
 703                        break;
 704                case ICMP_SR_FAILED:
 705                        LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
 706                                       &iph->daddr);
 707                        break;
 708                default:
 709                        break;
 710                }
 711                if (icmph->code > NR_ICMP_UNREACH)
 712                        goto out;
 713        } else if (icmph->type == ICMP_PARAMETERPROB)
 714                info = ntohl(icmph->un.gateway) >> 24;
 715
 716        /*
 717         *      Throw it at our lower layers
 718         *
 719         *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 720         *                header.
 721         *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 722         *                transport layer.
 723         *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 724         *                transport layer.
 725         */
 726
 727        /*
 728         *      Check the other end isn't violating RFC 1122. Some routers send
 729         *      bogus responses to broadcast frames. If you see this message
 730         *      first check your netmask matches at both ends, if it does then
 731         *      get the other vendor to fix their kit.
 732         */
 733
 734        if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 735            inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
 736                net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 737                                     &ip_hdr(skb)->saddr,
 738                                     icmph->type, icmph->code,
 739                                     &iph->daddr, skb->dev->name);
 740                goto out;
 741        }
 742
 743        icmp_socket_deliver(skb, info);
 744
 745out:
 746        return;
 747out_err:
 748        ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 749        goto out;
 750}
 751
 752
 753/*
 754 *      Handle ICMP_REDIRECT.
 755 */
 756
 757static void icmp_redirect(struct sk_buff *skb)
 758{
 759        if (skb->len < sizeof(struct iphdr)) {
 760                ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
 761                return;
 762        }
 763
 764        if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 765                return;
 766
 767        icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
 768}
 769
 770/*
 771 *      Handle ICMP_ECHO ("ping") requests.
 772 *
 773 *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 774 *                requests.
 775 *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 776 *                included in the reply.
 777 *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 778 *                echo requests, MUST have default=NOT.
 779 *      See also WRT handling of options once they are done and working.
 780 */
 781
 782static void icmp_echo(struct sk_buff *skb)
 783{
 784        struct net *net;
 785
 786        net = dev_net(skb_dst(skb)->dev);
 787        if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 788                struct icmp_bxm icmp_param;
 789
 790                icmp_param.data.icmph      = *icmp_hdr(skb);
 791                icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 792                icmp_param.skb             = skb;
 793                icmp_param.offset          = 0;
 794                icmp_param.data_len        = skb->len;
 795                icmp_param.head_len        = sizeof(struct icmphdr);
 796                icmp_reply(&icmp_param, skb);
 797        }
 798}
 799
 800/*
 801 *      Handle ICMP Timestamp requests.
 802 *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
 803 *                SHOULD be in the kernel for minimum random latency.
 804 *                MUST be accurate to a few minutes.
 805 *                MUST be updated at least at 15Hz.
 806 */
 807static void icmp_timestamp(struct sk_buff *skb)
 808{
 809        struct timespec tv;
 810        struct icmp_bxm icmp_param;
 811        /*
 812         *      Too short.
 813         */
 814        if (skb->len < 4)
 815                goto out_err;
 816
 817        /*
 818         *      Fill in the current time as ms since midnight UT:
 819         */
 820        getnstimeofday(&tv);
 821        icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
 822                                         tv.tv_nsec / NSEC_PER_MSEC);
 823        icmp_param.data.times[2] = icmp_param.data.times[1];
 824        if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
 825                BUG();
 826        icmp_param.data.icmph      = *icmp_hdr(skb);
 827        icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
 828        icmp_param.data.icmph.code = 0;
 829        icmp_param.skb             = skb;
 830        icmp_param.offset          = 0;
 831        icmp_param.data_len        = 0;
 832        icmp_param.head_len        = sizeof(struct icmphdr) + 12;
 833        icmp_reply(&icmp_param, skb);
 834out:
 835        return;
 836out_err:
 837        ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 838        goto out;
 839}
 840
 841static void icmp_discard(struct sk_buff *skb)
 842{
 843}
 844
 845/*
 846 *      Deal with incoming ICMP packets.
 847 */
 848int icmp_rcv(struct sk_buff *skb)
 849{
 850        struct icmphdr *icmph;
 851        struct rtable *rt = skb_rtable(skb);
 852        struct net *net = dev_net(rt->dst.dev);
 853
 854        if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 855                struct sec_path *sp = skb_sec_path(skb);
 856                int nh;
 857
 858                if (!(sp && sp->xvec[sp->len - 1]->props.flags &
 859                                 XFRM_STATE_ICMP))
 860                        goto drop;
 861
 862                if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
 863                        goto drop;
 864
 865                nh = skb_network_offset(skb);
 866                skb_set_network_header(skb, sizeof(*icmph));
 867
 868                if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
 869                        goto drop;
 870
 871                skb_set_network_header(skb, nh);
 872        }
 873
 874        ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
 875
 876        switch (skb->ip_summed) {
 877        case CHECKSUM_COMPLETE:
 878                if (!csum_fold(skb->csum))
 879                        break;
 880                /* fall through */
 881        case CHECKSUM_NONE:
 882                skb->csum = 0;
 883                if (__skb_checksum_complete(skb))
 884                        goto error;
 885        }
 886
 887        if (!pskb_pull(skb, sizeof(*icmph)))
 888                goto error;
 889
 890        icmph = icmp_hdr(skb);
 891
 892        ICMPMSGIN_INC_STATS_BH(net, icmph->type);
 893        /*
 894         *      18 is the highest 'known' ICMP type. Anything else is a mystery
 895         *
 896         *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 897         *                discarded.
 898         */
 899        if (icmph->type > NR_ICMP_TYPES)
 900                goto error;
 901
 902
 903        /*
 904         *      Parse the ICMP message
 905         */
 906
 907        if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
 908                /*
 909                 *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
 910                 *        silently ignored (we let user decide with a sysctl).
 911                 *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
 912                 *        discarded if to broadcast/multicast.
 913                 */
 914                if ((icmph->type == ICMP_ECHO ||
 915                     icmph->type == ICMP_TIMESTAMP) &&
 916                    net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
 917                        goto error;
 918                }
 919                if (icmph->type != ICMP_ECHO &&
 920                    icmph->type != ICMP_TIMESTAMP &&
 921                    icmph->type != ICMP_ADDRESS &&
 922                    icmph->type != ICMP_ADDRESSREPLY) {
 923                        goto error;
 924                }
 925        }
 926
 927        icmp_pointers[icmph->type].handler(skb);
 928
 929drop:
 930        kfree_skb(skb);
 931        return 0;
 932error:
 933        ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 934        goto drop;
 935}
 936
 937/*
 938 *      This table is the definition of how we handle ICMP.
 939 */
 940static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
 941        [ICMP_ECHOREPLY] = {
 942                .handler = ping_rcv,
 943        },
 944        [1] = {
 945                .handler = icmp_discard,
 946                .error = 1,
 947        },
 948        [2] = {
 949                .handler = icmp_discard,
 950                .error = 1,
 951        },
 952        [ICMP_DEST_UNREACH] = {
 953                .handler = icmp_unreach,
 954                .error = 1,
 955        },
 956        [ICMP_SOURCE_QUENCH] = {
 957                .handler = icmp_unreach,
 958                .error = 1,
 959        },
 960        [ICMP_REDIRECT] = {
 961                .handler = icmp_redirect,
 962                .error = 1,
 963        },
 964        [6] = {
 965                .handler = icmp_discard,
 966                .error = 1,
 967        },
 968        [7] = {
 969                .handler = icmp_discard,
 970                .error = 1,
 971        },
 972        [ICMP_ECHO] = {
 973                .handler = icmp_echo,
 974        },
 975        [9] = {
 976                .handler = icmp_discard,
 977                .error = 1,
 978        },
 979        [10] = {
 980                .handler = icmp_discard,
 981                .error = 1,
 982        },
 983        [ICMP_TIME_EXCEEDED] = {
 984                .handler = icmp_unreach,
 985                .error = 1,
 986        },
 987        [ICMP_PARAMETERPROB] = {
 988                .handler = icmp_unreach,
 989                .error = 1,
 990        },
 991        [ICMP_TIMESTAMP] = {
 992                .handler = icmp_timestamp,
 993        },
 994        [ICMP_TIMESTAMPREPLY] = {
 995                .handler = icmp_discard,
 996        },
 997        [ICMP_INFO_REQUEST] = {
 998                .handler = icmp_discard,
 999        },
1000        [ICMP_INFO_REPLY] = {
1001                .handler = icmp_discard,
1002        },
1003        [ICMP_ADDRESS] = {
1004                .handler = icmp_discard,
1005        },
1006        [ICMP_ADDRESSREPLY] = {
1007                .handler = icmp_discard,
1008        },
1009};
1010
1011static void __net_exit icmp_sk_exit(struct net *net)
1012{
1013        int i;
1014
1015        for_each_possible_cpu(i)
1016                inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1017        kfree(net->ipv4.icmp_sk);
1018        net->ipv4.icmp_sk = NULL;
1019}
1020
1021static int __net_init icmp_sk_init(struct net *net)
1022{
1023        int i, err;
1024
1025        net->ipv4.icmp_sk =
1026                kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1027        if (net->ipv4.icmp_sk == NULL)
1028                return -ENOMEM;
1029
1030        for_each_possible_cpu(i) {
1031                struct sock *sk;
1032
1033                err = inet_ctl_sock_create(&sk, PF_INET,
1034                                           SOCK_RAW, IPPROTO_ICMP, net);
1035                if (err < 0)
1036                        goto fail;
1037
1038                net->ipv4.icmp_sk[i] = sk;
1039
1040                /* Enough space for 2 64K ICMP packets, including
1041                 * sk_buff/skb_shared_info struct overhead.
1042                 */
1043                sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1044
1045                /*
1046                 * Speedup sock_wfree()
1047                 */
1048                sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1049                inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1050        }
1051
1052        /* Control parameters for ECHO replies. */
1053        net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1054        net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1055
1056        /* Control parameter - ignore bogus broadcast responses? */
1057        net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1058
1059        /*
1060         *      Configurable global rate limit.
1061         *
1062         *      ratelimit defines tokens/packet consumed for dst->rate_token
1063         *      bucket ratemask defines which icmp types are ratelimited by
1064         *      setting it's bit position.
1065         *
1066         *      default:
1067         *      dest unreachable (3), source quench (4),
1068         *      time exceeded (11), parameter problem (12)
1069         */
1070
1071        net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1072        net->ipv4.sysctl_icmp_ratemask = 0x1818;
1073        net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1074
1075        return 0;
1076
1077fail:
1078        for_each_possible_cpu(i)
1079                inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1080        kfree(net->ipv4.icmp_sk);
1081        return err;
1082}
1083
1084static struct pernet_operations __net_initdata icmp_sk_ops = {
1085       .init = icmp_sk_init,
1086       .exit = icmp_sk_exit,
1087};
1088
1089int __init icmp_init(void)
1090{
1091        return register_pernet_subsys(&icmp_sk_ops);
1092}
1093
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