net/ipv4/icmp.c

   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
 104 struct 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
 120 const 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 };
 186 EXPORT_SYMBOL(icmp_err_convert);
 187
 188 /*
 189  *      ICMP control array. This specifies what to do with each ICMP.
 190  */
 191
 192 struct icmp_control {
 193         void (*handler)(struct sk_buff *skb);
 194         short   error;          /* This ICMP is classed as an error message */
 195 };
 196
 197 static 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  */
 206 static struct sock *icmp_sk(struct net *net)
 207 {
 208         return net->ipv4.icmp_sk[smp_processor_id()];
 209 }
 210
 211 static 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
 229 static 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
 238 static 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         }
 263 out:
 264         return rc;
 265 }
 266
 267 /*
 268  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 269  */
 270 void 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  */
 280 static 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
 296 static 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
 331 static 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);
 374 out_unlock:
 375         icmp_xmit_unlock(sk);
 376 }
 377
 378 static 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
 464 relookup_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
 481 void 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);
 629 ende:
 630         ip_rt_put(rt);
 631 out_unlock:
 632         icmp_xmit_unlock(sk);
 633 out:;
 634 }
 635 EXPORT_SYMBOL(icmp_send);
 636
 637
 638 static 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
 663 static 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
 745 out:
 746         return;
 747 out_err:
 748         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 749         goto out;
 750 }
 751
 752
 753 /*
 754  *      Handle ICMP_REDIRECT.
 755  */
 756
 757 static 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
 782 static 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  */
 807 static 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);
 834 out:
 835         return;
 836 out_err:
 837         ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 838         goto out;
 839 }
 840
 841 static void icmp_discard(struct sk_buff *skb)
 842 {
 843 }
 844
 845 /*
 846  *      Deal with incoming ICMP packets.
 847  */
 848 int 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 csum_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
 929 drop:
 930         kfree_skb(skb);
 931         return 0;
 932 csum_error:
 933         ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
 934 error:
 935         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 936         goto drop;
 937 }
 938
 939 void icmp_err(struct sk_buff *skb, u32 info)
 940 {
 941         struct iphdr *iph = (struct iphdr *)skb->data;
 942         struct icmphdr *icmph = (struct icmphdr *)(skb->data+(iph->ihl<<2));
 943         int type = icmp_hdr(skb)->type;
 944         int code = icmp_hdr(skb)->code;
 945         struct net *net = dev_net(skb->dev);
 946
 947         /*
 948          * Use ping_err to handle all icmp errors except those
 949          * triggered by ICMP_ECHOREPLY which sent from kernel.
 950          */
 951         if (icmph->type != ICMP_ECHOREPLY) {
 952                 ping_err(skb, info);
 953                 return;
 954         }
 955
 956         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 957                 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
 958         else if (type == ICMP_REDIRECT)
 959                 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
 960 }
 961
 962 /*
 963  *      This table is the definition of how we handle ICMP.
 964  */
 965 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
 966         [ICMP_ECHOREPLY] = {
 967                 .handler = ping_rcv,
 968         },
 969         [1] = {
 970                 .handler = icmp_discard,
 971                 .error = 1,
 972         },
 973         [2] = {
 974                 .handler = icmp_discard,
 975                 .error = 1,
 976         },
 977         [ICMP_DEST_UNREACH] = {
 978                 .handler = icmp_unreach,
 979                 .error = 1,
 980         },
 981         [ICMP_SOURCE_QUENCH] = {
 982                 .handler = icmp_unreach,
 983                 .error = 1,
 984         },
 985         [ICMP_REDIRECT] = {
 986                 .handler = icmp_redirect,
 987                 .error = 1,
 988         },
 989         [6] = {
 990                 .handler = icmp_discard,
 991                 .error = 1,
 992         },
 993         [7] = {
 994                 .handler = icmp_discard,
 995                 .error = 1,
 996         },
 997         [ICMP_ECHO] = {
 998                 .handler = icmp_echo,
 999         },
1000         [9] = {
1001                 .handler = icmp_discard,
1002                 .error = 1,
1003         },
1004         [10] = {
1005                 .handler = icmp_discard,
1006                 .error = 1,
1007         },
1008         [ICMP_TIME_EXCEEDED] = {
1009                 .handler = icmp_unreach,
1010                 .error = 1,
1011         },
1012         [ICMP_PARAMETERPROB] = {
1013                 .handler = icmp_unreach,
1014                 .error = 1,
1015         },
1016         [ICMP_TIMESTAMP] = {
1017                 .handler = icmp_timestamp,
1018         },
1019         [ICMP_TIMESTAMPREPLY] = {
1020                 .handler = icmp_discard,
1021         },
1022         [ICMP_INFO_REQUEST] = {
1023                 .handler = icmp_discard,
1024         },
1025         [ICMP_INFO_REPLY] = {
1026                 .handler = icmp_discard,
1027         },
1028         [ICMP_ADDRESS] = {
1029                 .handler = icmp_discard,
1030         },
1031         [ICMP_ADDRESSREPLY] = {
1032                 .handler = icmp_discard,
1033         },
1034 };
1035
1036 static void __net_exit icmp_sk_exit(struct net *net)
1037 {
1038         int i;
1039
1040         for_each_possible_cpu(i)
1041                 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1042         kfree(net->ipv4.icmp_sk);
1043         net->ipv4.icmp_sk = NULL;
1044 }
1045
1046 static int __net_init icmp_sk_init(struct net *net)
1047 {
1048         int i, err;
1049
1050         net->ipv4.icmp_sk =
1051                 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1052         if (net->ipv4.icmp_sk == NULL)
1053                 return -ENOMEM;
1054
1055         for_each_possible_cpu(i) {
1056                 struct sock *sk;
1057
1058                 err = inet_ctl_sock_create(&sk, PF_INET,
1059                                            SOCK_RAW, IPPROTO_ICMP, net);
1060                 if (err < 0)
1061                         goto fail;
1062
1063                 net->ipv4.icmp_sk[i] = sk;
1064
1065                 /* Enough space for 2 64K ICMP packets, including
1066                  * sk_buff/skb_shared_info struct overhead.
1067                  */
1068                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1069
1070                 /*
1071                  * Speedup sock_wfree()
1072                  */
1073                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1074                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1075         }
1076
1077         /* Control parameters for ECHO replies. */
1078         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1079         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1080
1081         /* Control parameter - ignore bogus broadcast responses? */
1082         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1083
1084         /*
1085          *      Configurable global rate limit.
1086          *
1087          *      ratelimit defines tokens/packet consumed for dst->rate_token
1088          *      bucket ratemask defines which icmp types are ratelimited by
1089          *      setting it's bit position.
1090          *
1091          *      default:
1092          *      dest unreachable (3), source quench (4),
1093          *      time exceeded (11), parameter problem (12)
1094          */
1095
1096         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1097         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1098         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1099
1100         return 0;
1101
1102 fail:
1103         for_each_possible_cpu(i)
1104                 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1105         kfree(net->ipv4.icmp_sk);
1106         return err;
1107 }
1108
1109 static struct pernet_operations __net_initdata icmp_sk_ops = {
1110        .init = icmp_sk_init,
1111        .exit = icmp_sk_exit,
1112 };
1113
1114 int __init icmp_init(void)
1115 {
1116         return register_pernet_subsys(&icmp_sk_ops);
1117 }