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         ipc.ttl = 0;
 357         ipc.tos = -1;
 358
 359         if (icmp_param->replyopts.opt.opt.optlen) {
 360                 ipc.opt = &icmp_param->replyopts.opt;
 361                 if (ipc.opt->opt.srr)
 362                         daddr = icmp_param->replyopts.opt.opt.faddr;
 363         }
 364         memset(&fl4, 0, sizeof(fl4));
 365         fl4.daddr = daddr;
 366         fl4.saddr = saddr;
 367         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 368         fl4.flowi4_proto = IPPROTO_ICMP;
 369         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
 370         rt = ip_route_output_key(net, &fl4);
 371         if (IS_ERR(rt))
 372                 goto out_unlock;
 373         if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
 374                                icmp_param->data.icmph.code))
 375                 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 376         ip_rt_put(rt);
 377 out_unlock:
 378         icmp_xmit_unlock(sk);
 379 }
 380
 381 static struct rtable *icmp_route_lookup(struct net *net,
 382                                         struct flowi4 *fl4,
 383                                         struct sk_buff *skb_in,
 384                                         const struct iphdr *iph,
 385                                         __be32 saddr, u8 tos,
 386                                         int type, int code,
 387                                         struct icmp_bxm *param)
 388 {
 389         struct rtable *rt, *rt2;
 390         struct flowi4 fl4_dec;
 391         int err;
 392
 393         memset(fl4, 0, sizeof(*fl4));
 394         fl4->daddr = (param->replyopts.opt.opt.srr ?
 395                       param->replyopts.opt.opt.faddr : iph->saddr);
 396         fl4->saddr = saddr;
 397         fl4->flowi4_tos = RT_TOS(tos);
 398         fl4->flowi4_proto = IPPROTO_ICMP;
 399         fl4->fl4_icmp_type = type;
 400         fl4->fl4_icmp_code = code;
 401         security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
 402         rt = __ip_route_output_key(net, fl4);
 403         if (IS_ERR(rt))
 404                 return rt;
 405
 406         /* No need to clone since we're just using its address. */
 407         rt2 = rt;
 408
 409         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 410                                            flowi4_to_flowi(fl4), NULL, 0);
 411         if (!IS_ERR(rt)) {
 412                 if (rt != rt2)
 413                         return rt;
 414         } else if (PTR_ERR(rt) == -EPERM) {
 415                 rt = NULL;
 416         } else
 417                 return rt;
 418
 419         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 420         if (err)
 421                 goto relookup_failed;
 422
 423         if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
 424                 rt2 = __ip_route_output_key(net, &fl4_dec);
 425                 if (IS_ERR(rt2))
 426                         err = PTR_ERR(rt2);
 427         } else {
 428                 struct flowi4 fl4_2 = {};
 429                 unsigned long orefdst;
 430
 431                 fl4_2.daddr = fl4_dec.saddr;
 432                 rt2 = ip_route_output_key(net, &fl4_2);
 433                 if (IS_ERR(rt2)) {
 434                         err = PTR_ERR(rt2);
 435                         goto relookup_failed;
 436                 }
 437                 /* Ugh! */
 438                 orefdst = skb_in->_skb_refdst; /* save old refdst */
 439                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 440                                      RT_TOS(tos), rt2->dst.dev);
 441
 442                 dst_release(&rt2->dst);
 443                 rt2 = skb_rtable(skb_in);
 444                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
 445         }
 446
 447         if (err)
 448                 goto relookup_failed;
 449
 450         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 451                                             flowi4_to_flowi(&fl4_dec), NULL,
 452                                             XFRM_LOOKUP_ICMP);
 453         if (!IS_ERR(rt2)) {
 454                 dst_release(&rt->dst);
 455                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
 456                 rt = rt2;
 457         } else if (PTR_ERR(rt2) == -EPERM) {
 458                 if (rt)
 459                         dst_release(&rt->dst);
 460                 return rt2;
 461         } else {
 462                 err = PTR_ERR(rt2);
 463                 goto relookup_failed;
 464         }
 465         return rt;
 466
 467 relookup_failed:
 468         if (rt)
 469                 return rt;
 470         return ERR_PTR(err);
 471 }
 472
 473 /*
 474  *      Send an ICMP message in response to a situation
 475  *
 476  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 477  *                MAY send more (we do).
 478  *                      MUST NOT change this header information.
 479  *                      MUST NOT reply to a multicast/broadcast IP address.
 480  *                      MUST NOT reply to a multicast/broadcast MAC address.
 481  *                      MUST reply to only the first fragment.
 482  */
 483
 484 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 485 {
 486         struct iphdr *iph;
 487         int room;
 488         struct icmp_bxm *icmp_param;
 489         struct rtable *rt = skb_rtable(skb_in);
 490         struct ipcm_cookie ipc;
 491         struct flowi4 fl4;
 492         __be32 saddr;
 493         u8  tos;
 494         struct net *net;
 495         struct sock *sk;
 496
 497         if (!rt)
 498                 goto out;
 499         net = dev_net(rt->dst.dev);
 500
 501         /*
 502          *      Find the original header. It is expected to be valid, of course.
 503          *      Check this, icmp_send is called from the most obscure devices
 504          *      sometimes.
 505          */
 506         iph = ip_hdr(skb_in);
 507
 508         if ((u8 *)iph < skb_in->head ||
 509             (skb_network_header(skb_in) + sizeof(*iph)) >
 510             skb_tail_pointer(skb_in))
 511                 goto out;
 512
 513         /*
 514          *      No replies to physical multicast/broadcast
 515          */
 516         if (skb_in->pkt_type != PACKET_HOST)
 517                 goto out;
 518
 519         /*
 520          *      Now check at the protocol level
 521          */
 522         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 523                 goto out;
 524
 525         /*
 526          *      Only reply to fragment 0. We byte re-order the constant
 527          *      mask for efficiency.
 528          */
 529         if (iph->frag_off & htons(IP_OFFSET))
 530                 goto out;
 531
 532         /*
 533          *      If we send an ICMP error to an ICMP error a mess would result..
 534          */
 535         if (icmp_pointers[type].error) {
 536                 /*
 537                  *      We are an error, check if we are replying to an
 538                  *      ICMP error
 539                  */
 540                 if (iph->protocol == IPPROTO_ICMP) {
 541                         u8 _inner_type, *itp;
 542
 543                         itp = skb_header_pointer(skb_in,
 544                                                  skb_network_header(skb_in) +
 545                                                  (iph->ihl << 2) +
 546                                                  offsetof(struct icmphdr,
 547                                                           type) -
 548                                                  skb_in->data,
 549                                                  sizeof(_inner_type),
 550                                                  &_inner_type);
 551                         if (itp == NULL)
 552                                 goto out;
 553
 554                         /*
 555                          *      Assume any unknown ICMP type is an error. This
 556                          *      isn't specified by the RFC, but think about it..
 557                          */
 558                         if (*itp > NR_ICMP_TYPES ||
 559                             icmp_pointers[*itp].error)
 560                                 goto out;
 561                 }
 562         }
 563
 564         icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
 565         if (!icmp_param)
 566                 return;
 567
 568         sk = icmp_xmit_lock(net);
 569         if (sk == NULL)
 570                 goto out_free;
 571
 572         /*
 573          *      Construct source address and options.
 574          */
 575
 576         saddr = iph->daddr;
 577         if (!(rt->rt_flags & RTCF_LOCAL)) {
 578                 struct net_device *dev = NULL;
 579
 580                 rcu_read_lock();
 581                 if (rt_is_input_route(rt) &&
 582                     net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 583                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 584
 585                 if (dev)
 586                         saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
 587                 else
 588                         saddr = 0;
 589                 rcu_read_unlock();
 590         }
 591
 592         tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
 593                                            IPTOS_PREC_INTERNETCONTROL) :
 594                                           iph->tos;
 595
 596         if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
 597                 goto out_unlock;
 598
 599
 600         /*
 601          *      Prepare data for ICMP header.
 602          */
 603
 604         icmp_param->data.icmph.type      = type;
 605         icmp_param->data.icmph.code      = code;
 606         icmp_param->data.icmph.un.gateway = info;
 607         icmp_param->data.icmph.checksum  = 0;
 608         icmp_param->skb   = skb_in;
 609         icmp_param->offset = skb_network_offset(skb_in);
 610         inet_sk(sk)->tos = tos;
 611         ipc.addr = iph->saddr;
 612         ipc.opt = &icmp_param->replyopts.opt;
 613         ipc.tx_flags = 0;
 614         ipc.ttl = 0;
 615         ipc.tos = -1;
 616
 617         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
 618                                type, code, icmp_param);
 619         if (IS_ERR(rt))
 620                 goto out_unlock;
 621
 622         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 623                 goto ende;
 624
 625         /* RFC says return as much as we can without exceeding 576 bytes. */
 626
 627         room = dst_mtu(&rt->dst);
 628         if (room > 576)
 629                 room = 576;
 630         room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
 631         room -= sizeof(struct icmphdr);
 632
 633         icmp_param->data_len = skb_in->len - icmp_param->offset;
 634         if (icmp_param->data_len > room)
 635                 icmp_param->data_len = room;
 636         icmp_param->head_len = sizeof(struct icmphdr);
 637
 638         icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 639 ende:
 640         ip_rt_put(rt);
 641 out_unlock:
 642         icmp_xmit_unlock(sk);
 643 out_free:
 644         kfree(icmp_param);
 645 out:;
 646 }
 647 EXPORT_SYMBOL(icmp_send);
 648
 649
 650 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 651 {
 652         const struct iphdr *iph = (const struct iphdr *) skb->data;
 653         const struct net_protocol *ipprot;
 654         int protocol = iph->protocol;
 655
 656         /* Checkin full IP header plus 8 bytes of protocol to
 657          * avoid additional coding at protocol handlers.
 658          */
 659         if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
 660                 return;
 661
 662         raw_icmp_error(skb, protocol, info);
 663
 664         rcu_read_lock();
 665         ipprot = rcu_dereference(inet_protos[protocol]);
 666         if (ipprot && ipprot->err_handler)
 667                 ipprot->err_handler(skb, info);
 668         rcu_read_unlock();
 669 }
 670
 671 static bool icmp_tag_validation(int proto)
 672 {
 673         bool ok;
 674
 675         rcu_read_lock();
 676         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 677         rcu_read_unlock();
 678         return ok;
 679 }
 680
 681 /*
 682  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
 683  *      ICMP_PARAMETERPROB.
 684  */
 685
 686 static void icmp_unreach(struct sk_buff *skb)
 687 {
 688         const struct iphdr *iph;
 689         struct icmphdr *icmph;
 690         struct net *net;
 691         u32 info = 0;
 692
 693         net = dev_net(skb_dst(skb)->dev);
 694
 695         /*
 696          *      Incomplete header ?
 697          *      Only checks for the IP header, there should be an
 698          *      additional check for longer headers in upper levels.
 699          */
 700
 701         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 702                 goto out_err;
 703
 704         icmph = icmp_hdr(skb);
 705         iph   = (const struct iphdr *)skb->data;
 706
 707         if (iph->ihl < 5) /* Mangled header, drop. */
 708                 goto out_err;
 709
 710         if (icmph->type == ICMP_DEST_UNREACH) {
 711                 switch (icmph->code & 15) {
 712                 case ICMP_NET_UNREACH:
 713                 case ICMP_HOST_UNREACH:
 714                 case ICMP_PROT_UNREACH:
 715                 case ICMP_PORT_UNREACH:
 716                         break;
 717                 case ICMP_FRAG_NEEDED:
 718                         /* for documentation of the ip_no_pmtu_disc
 719                          * values please see
 720                          * Documentation/networking/ip-sysctl.txt
 721                          */
 722                         switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
 723                         default:
 724                                 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
 725                                                &iph->daddr);
 726                                 break;
 727                         case 2:
 728                                 goto out;
 729                         case 3:
 730                                 if (!icmp_tag_validation(iph->protocol))
 731                                         goto out;
 732                                 /* fall through */
 733                         case 0:
 734                                 info = ntohs(icmph->un.frag.mtu);
 735                         }
 736                         break;
 737                 case ICMP_SR_FAILED:
 738                         LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
 739                                        &iph->daddr);
 740                         break;
 741                 default:
 742                         break;
 743                 }
 744                 if (icmph->code > NR_ICMP_UNREACH)
 745                         goto out;
 746         } else if (icmph->type == ICMP_PARAMETERPROB)
 747                 info = ntohl(icmph->un.gateway) >> 24;
 748
 749         /*
 750          *      Throw it at our lower layers
 751          *
 752          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 753          *                header.
 754          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 755          *                transport layer.
 756          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 757          *                transport layer.
 758          */
 759
 760         /*
 761          *      Check the other end isn't violating RFC 1122. Some routers send
 762          *      bogus responses to broadcast frames. If you see this message
 763          *      first check your netmask matches at both ends, if it does then
 764          *      get the other vendor to fix their kit.
 765          */
 766
 767         if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 768             inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
 769                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 770                                      &ip_hdr(skb)->saddr,
 771                                      icmph->type, icmph->code,
 772                                      &iph->daddr, skb->dev->name);
 773                 goto out;
 774         }
 775
 776         icmp_socket_deliver(skb, info);
 777
 778 out:
 779         return;
 780 out_err:
 781         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 782         goto out;
 783 }
 784
 785
 786 /*
 787  *      Handle ICMP_REDIRECT.
 788  */
 789
 790 static void icmp_redirect(struct sk_buff *skb)
 791 {
 792         if (skb->len < sizeof(struct iphdr)) {
 793                 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
 794                 return;
 795         }
 796
 797         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 798                 return;
 799
 800         icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
 801 }
 802
 803 /*
 804  *      Handle ICMP_ECHO ("ping") requests.
 805  *
 806  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 807  *                requests.
 808  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 809  *                included in the reply.
 810  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 811  *                echo requests, MUST have default=NOT.
 812  *      See also WRT handling of options once they are done and working.
 813  */
 814
 815 static void icmp_echo(struct sk_buff *skb)
 816 {
 817         struct net *net;
 818
 819         net = dev_net(skb_dst(skb)->dev);
 820         if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
 821                 struct icmp_bxm icmp_param;
 822
 823                 icmp_param.data.icmph      = *icmp_hdr(skb);
 824                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
 825                 icmp_param.skb             = skb;
 826                 icmp_param.offset          = 0;
 827                 icmp_param.data_len        = skb->len;
 828                 icmp_param.head_len        = sizeof(struct icmphdr);
 829                 icmp_reply(&icmp_param, skb);
 830         }
 831 }
 832
 833 /*
 834  *      Handle ICMP Timestamp requests.
 835  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
 836  *                SHOULD be in the kernel for minimum random latency.
 837  *                MUST be accurate to a few minutes.
 838  *                MUST be updated at least at 15Hz.
 839  */
 840 static void icmp_timestamp(struct sk_buff *skb)
 841 {
 842         struct timespec tv;
 843         struct icmp_bxm icmp_param;
 844         /*
 845          *      Too short.
 846          */
 847         if (skb->len < 4)
 848                 goto out_err;
 849
 850         /*
 851          *      Fill in the current time as ms since midnight UT:
 852          */
 853         getnstimeofday(&tv);
 854         icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
 855                                          tv.tv_nsec / NSEC_PER_MSEC);
 856         icmp_param.data.times[2] = icmp_param.data.times[1];
 857         if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
 858                 BUG();
 859         icmp_param.data.icmph      = *icmp_hdr(skb);
 860         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
 861         icmp_param.data.icmph.code = 0;
 862         icmp_param.skb             = skb;
 863         icmp_param.offset          = 0;
 864         icmp_param.data_len        = 0;
 865         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
 866         icmp_reply(&icmp_param, skb);
 867 out:
 868         return;
 869 out_err:
 870         ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
 871         goto out;
 872 }
 873
 874 static void icmp_discard(struct sk_buff *skb)
 875 {
 876 }
 877
 878 /*
 879  *      Deal with incoming ICMP packets.
 880  */
 881 int icmp_rcv(struct sk_buff *skb)
 882 {
 883         struct icmphdr *icmph;
 884         struct rtable *rt = skb_rtable(skb);
 885         struct net *net = dev_net(rt->dst.dev);
 886
 887         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 888                 struct sec_path *sp = skb_sec_path(skb);
 889                 int nh;
 890
 891                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
 892                                  XFRM_STATE_ICMP))
 893                         goto drop;
 894
 895                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
 896                         goto drop;
 897
 898                 nh = skb_network_offset(skb);
 899                 skb_set_network_header(skb, sizeof(*icmph));
 900
 901                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
 902                         goto drop;
 903
 904                 skb_set_network_header(skb, nh);
 905         }
 906
 907         ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
 908
 909         switch (skb->ip_summed) {
 910         case CHECKSUM_COMPLETE:
 911                 if (!csum_fold(skb->csum))
 912                         break;
 913                 /* fall through */
 914         case CHECKSUM_NONE:
 915                 skb->csum = 0;
 916                 if (__skb_checksum_complete(skb))
 917                         goto csum_error;
 918         }
 919
 920         if (!pskb_pull(skb, sizeof(*icmph)))
 921                 goto error;
 922
 923         icmph = icmp_hdr(skb);
 924
 925         ICMPMSGIN_INC_STATS_BH(net, icmph->type);
 926         /*
 927          *      18 is the highest 'known' ICMP type. Anything else is a mystery
 928          *
 929          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 930          *                discarded.
 931          */
 932         if (icmph->type > NR_ICMP_TYPES)
 933                 goto error;
 934
 935
 936         /*
 937          *      Parse the ICMP message
 938          */
 939
 940         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
 941                 /*
 942                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
 943                  *        silently ignored (we let user decide with a sysctl).
 944                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
 945                  *        discarded if to broadcast/multicast.
 946                  */
 947                 if ((icmph->type == ICMP_ECHO ||
 948                      icmph->type == ICMP_TIMESTAMP) &&
 949                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
 950                         goto error;
 951                 }
 952                 if (icmph->type != ICMP_ECHO &&
 953                     icmph->type != ICMP_TIMESTAMP &&
 954                     icmph->type != ICMP_ADDRESS &&
 955                     icmph->type != ICMP_ADDRESSREPLY) {
 956                         goto error;
 957                 }
 958         }
 959
 960         icmp_pointers[icmph->type].handler(skb);
 961
 962 drop:
 963         kfree_skb(skb);
 964         return 0;
 965 csum_error:
 966         ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
 967 error:
 968         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 969         goto drop;
 970 }
 971
 972 void icmp_err(struct sk_buff *skb, u32 info)
 973 {
 974         struct iphdr *iph = (struct iphdr *)skb->data;
 975         int offset = iph->ihl<<2;
 976         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
 977         int type = icmp_hdr(skb)->type;
 978         int code = icmp_hdr(skb)->code;
 979         struct net *net = dev_net(skb->dev);
 980
 981         /*
 982          * Use ping_err to handle all icmp errors except those
 983          * triggered by ICMP_ECHOREPLY which sent from kernel.
 984          */
 985         if (icmph->type != ICMP_ECHOREPLY) {
 986                 ping_err(skb, offset, info);
 987                 return;
 988         }
 989
 990         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 991                 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
 992         else if (type == ICMP_REDIRECT)
 993                 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
 994 }
 995
 996 /*
 997  *      This table is the definition of how we handle ICMP.
 998  */
 999 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1000         [ICMP_ECHOREPLY] = {
1001                 .handler = ping_rcv,
1002         },
1003         [1] = {
1004                 .handler = icmp_discard,
1005                 .error = 1,
1006         },
1007         [2] = {
1008                 .handler = icmp_discard,
1009                 .error = 1,
1010         },
1011         [ICMP_DEST_UNREACH] = {
1012                 .handler = icmp_unreach,
1013                 .error = 1,
1014         },
1015         [ICMP_SOURCE_QUENCH] = {
1016                 .handler = icmp_unreach,
1017                 .error = 1,
1018         },
1019         [ICMP_REDIRECT] = {
1020                 .handler = icmp_redirect,
1021                 .error = 1,
1022         },
1023         [6] = {
1024                 .handler = icmp_discard,
1025                 .error = 1,
1026         },
1027         [7] = {
1028                 .handler = icmp_discard,
1029                 .error = 1,
1030         },
1031         [ICMP_ECHO] = {
1032                 .handler = icmp_echo,
1033         },
1034         [9] = {
1035                 .handler = icmp_discard,
1036                 .error = 1,
1037         },
1038         [10] = {
1039                 .handler = icmp_discard,
1040                 .error = 1,
1041         },
1042         [ICMP_TIME_EXCEEDED] = {
1043                 .handler = icmp_unreach,
1044                 .error = 1,
1045         },
1046         [ICMP_PARAMETERPROB] = {
1047                 .handler = icmp_unreach,
1048                 .error = 1,
1049         },
1050         [ICMP_TIMESTAMP] = {
1051                 .handler = icmp_timestamp,
1052         },
1053         [ICMP_TIMESTAMPREPLY] = {
1054                 .handler = icmp_discard,
1055         },
1056         [ICMP_INFO_REQUEST] = {
1057                 .handler = icmp_discard,
1058         },
1059         [ICMP_INFO_REPLY] = {
1060                 .handler = icmp_discard,
1061         },
1062         [ICMP_ADDRESS] = {
1063                 .handler = icmp_discard,
1064         },
1065         [ICMP_ADDRESSREPLY] = {
1066                 .handler = icmp_discard,
1067         },
1068 };
1069
1070 static void __net_exit icmp_sk_exit(struct net *net)
1071 {
1072         int i;
1073
1074         for_each_possible_cpu(i)
1075                 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1076         kfree(net->ipv4.icmp_sk);
1077         net->ipv4.icmp_sk = NULL;
1078 }
1079
1080 static int __net_init icmp_sk_init(struct net *net)
1081 {
1082         int i, err;
1083
1084         net->ipv4.icmp_sk =
1085                 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1086         if (net->ipv4.icmp_sk == NULL)
1087                 return -ENOMEM;
1088
1089         for_each_possible_cpu(i) {
1090                 struct sock *sk;
1091
1092                 err = inet_ctl_sock_create(&sk, PF_INET,
1093                                            SOCK_RAW, IPPROTO_ICMP, net);
1094                 if (err < 0)
1095                         goto fail;
1096
1097                 net->ipv4.icmp_sk[i] = sk;
1098
1099                 /* Enough space for 2 64K ICMP packets, including
1100                  * sk_buff/skb_shared_info struct overhead.
1101                  */
1102                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1103
1104                 /*
1105                  * Speedup sock_wfree()
1106                  */
1107                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1108                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1109         }
1110
1111         /* Control parameters for ECHO replies. */
1112         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1113         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1114
1115         /* Control parameter - ignore bogus broadcast responses? */
1116         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1117
1118         /*
1119          *      Configurable global rate limit.
1120          *
1121          *      ratelimit defines tokens/packet consumed for dst->rate_token
1122          *      bucket ratemask defines which icmp types are ratelimited by
1123          *      setting it's bit position.
1124          *
1125          *      default:
1126          *      dest unreachable (3), source quench (4),
1127          *      time exceeded (11), parameter problem (12)
1128          */
1129
1130         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1131         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1132         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1133
1134         return 0;
1135
1136 fail:
1137         for_each_possible_cpu(i)
1138                 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1139         kfree(net->ipv4.icmp_sk);
1140         return err;
1141 }
1142
1143 static struct pernet_operations __net_initdata icmp_sk_ops = {
1144        .init = icmp_sk_init,
1145        .exit = icmp_sk_exit,
1146 };
1147
1148 int __init icmp_init(void)
1149 {
1150         return register_pernet_subsys(&icmp_sk_ops);
1151 }