net/ipv4/icmp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      NET3:   Implementation of the ICMP protocol layer.
   4  *
   5  *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
   6  *
   7  *      Some of the function names and the icmp unreach table for this
   8  *      module were derived from [icmp.c 1.0.11 06/02/93] by
   9  *      Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
  10  *      Other than that this module is a complete rewrite.
  11  *
  12  *      Fixes:
  13  *      Clemens Fruhwirth       :       introduce global icmp rate limiting
  14  *                                      with icmp type masking ability instead
  15  *                                      of broken per type icmp timeouts.
  16  *              Mike Shaver     :       RFC1122 checks.
  17  *              Alan Cox        :       Multicast ping reply as self.
  18  *              Alan Cox        :       Fix atomicity lockup in ip_build_xmit
  19  *                                      call.
  20  *              Alan Cox        :       Added 216,128 byte paths to the MTU
  21  *                                      code.
  22  *              Martin Mares    :       RFC1812 checks.
  23  *              Martin Mares    :       Can be configured to follow redirects
  24  *                                      if acting as a router _without_ a
  25  *                                      routing protocol (RFC 1812).
  26  *              Martin Mares    :       Echo requests may be configured to
  27  *                                      be ignored (RFC 1812).
  28  *              Martin Mares    :       Limitation of ICMP error message
  29  *                                      transmit rate (RFC 1812).
  30  *              Martin Mares    :       TOS and Precedence set correctly
  31  *                                      (RFC 1812).
  32  *              Martin Mares    :       Now copying as much data from the
  33  *                                      original packet as we can without
  34  *                                      exceeding 576 bytes (RFC 1812).
  35  *      Willy Konynenberg       :       Transparent proxying support.
  36  *              Keith Owens     :       RFC1191 correction for 4.2BSD based
  37  *                                      path MTU bug.
  38  *              Thomas Quinot   :       ICMP Dest Unreach codes up to 15 are
  39  *                                      valid (RFC 1812).
  40  *              Andi Kleen      :       Check all packet lengths properly
  41  *                                      and moved all kfree_skb() up to
  42  *                                      icmp_rcv.
  43  *              Andi Kleen      :       Move the rate limit bookkeeping
  44  *                                      into the dest entry and use a token
  45  *                                      bucket filter (thanks to ANK). Make
  46  *                                      the rates sysctl configurable.
  47  *              Yu Tianli       :       Fixed two ugly bugs in icmp_send
  48  *                                      - IP option length was accounted wrongly
  49  *                                      - ICMP header length was not accounted
  50  *                                        at all.
  51  *              Tristan Greaves :       Added sysctl option to ignore bogus
  52  *                                      broadcast responses from broken routers.
  53  *
  54  * To Fix:
  55  *
  56  *      - Should use skb_pull() instead of all the manual checking.
  57  *        This would also greatly simply some upper layer error handlers. --AK
  58  */
  59
  60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  61
  62 #include <linux/module.h>
  63 #include <linux/types.h>
  64 #include <linux/jiffies.h>
  65 #include <linux/kernel.h>
  66 #include <linux/fcntl.h>
  67 #include <linux/socket.h>
  68 #include <linux/in.h>
  69 #include <linux/inet.h>
  70 #include <linux/inetdevice.h>
  71 #include <linux/netdevice.h>
  72 #include <linux/string.h>
  73 #include <linux/netfilter_ipv4.h>
  74 #include <linux/slab.h>
  75 #include <net/snmp.h>
  76 #include <net/ip.h>
  77 #include <net/route.h>
  78 #include <net/protocol.h>
  79 #include <net/icmp.h>
  80 #include <net/tcp.h>
  81 #include <net/udp.h>
  82 #include <net/raw.h>
  83 #include <net/ping.h>
  84 #include <linux/skbuff.h>
  85 #include <net/sock.h>
  86 #include <linux/errno.h>
  87 #include <linux/timer.h>
  88 #include <linux/init.h>
  89 #include <linux/uaccess.h>
  90 #include <net/checksum.h>
  91 #include <net/xfrm.h>
  92 #include <net/inet_common.h>
  93 #include <net/ip_fib.h>
  94 #include <net/l3mdev.h>
  95
  96 /*
  97  *      Build xmit assembly blocks
  98  */
  99
 100 struct icmp_bxm {
 101         struct sk_buff *skb;
 102         int offset;
 103         int data_len;
 104
 105         struct {
 106                 struct icmphdr icmph;
 107                 __be32         times[3];
 108         } data;
 109         int head_len;
 110         struct ip_options_data replyopts;
 111 };
 112
 113 /* An array of errno for error messages from dest unreach. */
 114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
 115
 116 const struct icmp_err icmp_err_convert[] = {
 117         {
 118                 .errno = ENETUNREACH,   /* ICMP_NET_UNREACH */
 119                 .fatal = 0,
 120         },
 121         {
 122                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNREACH */
 123                 .fatal = 0,
 124         },
 125         {
 126                 .errno = ENOPROTOOPT    /* ICMP_PROT_UNREACH */,
 127                 .fatal = 1,
 128         },
 129         {
 130                 .errno = ECONNREFUSED,  /* ICMP_PORT_UNREACH */
 131                 .fatal = 1,
 132         },
 133         {
 134                 .errno = EMSGSIZE,      /* ICMP_FRAG_NEEDED */
 135                 .fatal = 0,
 136         },
 137         {
 138                 .errno = EOPNOTSUPP,    /* ICMP_SR_FAILED */
 139                 .fatal = 0,
 140         },
 141         {
 142                 .errno = ENETUNREACH,   /* ICMP_NET_UNKNOWN */
 143                 .fatal = 1,
 144         },
 145         {
 146                 .errno = EHOSTDOWN,     /* ICMP_HOST_UNKNOWN */
 147                 .fatal = 1,
 148         },
 149         {
 150                 .errno = ENONET,        /* ICMP_HOST_ISOLATED */
 151                 .fatal = 1,
 152         },
 153         {
 154                 .errno = ENETUNREACH,   /* ICMP_NET_ANO */
 155                 .fatal = 1,
 156         },
 157         {
 158                 .errno = EHOSTUNREACH,  /* ICMP_HOST_ANO */
 159                 .fatal = 1,
 160         },
 161         {
 162                 .errno = ENETUNREACH,   /* ICMP_NET_UNR_TOS */
 163                 .fatal = 0,
 164         },
 165         {
 166                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNR_TOS */
 167                 .fatal = 0,
 168         },
 169         {
 170                 .errno = EHOSTUNREACH,  /* ICMP_PKT_FILTERED */
 171                 .fatal = 1,
 172         },
 173         {
 174                 .errno = EHOSTUNREACH,  /* ICMP_PREC_VIOLATION */
 175                 .fatal = 1,
 176         },
 177         {
 178                 .errno = EHOSTUNREACH,  /* ICMP_PREC_CUTOFF */
 179                 .fatal = 1,
 180         },
 181 };
 182 EXPORT_SYMBOL(icmp_err_convert);
 183
 184 /*
 185  *      ICMP control array. This specifies what to do with each ICMP.
 186  */
 187
 188 struct icmp_control {
 189         bool (*handler)(struct sk_buff *skb);
 190         short   error;          /* This ICMP is classed as an error message */
 191 };
 192
 193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 194
 195 /*
 196  *      The ICMP socket(s). This is the most convenient way to flow control
 197  *      our ICMP output as well as maintain a clean interface throughout
 198  *      all layers. All Socketless IP sends will soon be gone.
 199  *
 200  *      On SMP we have one ICMP socket per-cpu.
 201  */
 202 static struct sock *icmp_sk(struct net *net)
 203 {
 204         return this_cpu_read(*net->ipv4.icmp_sk);
 205 }
 206
 207 /* Called with BH disabled */
 208 static inline struct sock *icmp_xmit_lock(struct net *net)
 209 {
 210         struct sock *sk;
 211
 212         sk = icmp_sk(net);
 213
 214         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 215                 /* This can happen if the output path signals a
 216                  * dst_link_failure() for an outgoing ICMP packet.
 217                  */
 218                 return NULL;
 219         }
 220         return sk;
 221 }
 222
 223 static inline void icmp_xmit_unlock(struct sock *sk)
 224 {
 225         spin_unlock(&sk->sk_lock.slock);
 226 }
 227
 228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
 229 int sysctl_icmp_msgs_burst __read_mostly = 50;
 230
 231 static struct {
 232         spinlock_t      lock;
 233         u32             credit;
 234         u32             stamp;
 235 } icmp_global = {
 236         .lock           = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
 237 };
 238
 239 /**
 240  * icmp_global_allow - Are we allowed to send one more ICMP message ?
 241  *
 242  * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
 243  * Returns false if we reached the limit and can not send another packet.
 244  * Note: called with BH disabled
 245  */
 246 bool icmp_global_allow(void)
 247 {
 248         u32 credit, delta, incr = 0, now = (u32)jiffies;
 249         bool rc = false;
 250
 251         /* Check if token bucket is empty and cannot be refilled
 252          * without taking the spinlock. The READ_ONCE() are paired
 253          * with the following WRITE_ONCE() in this same function.
 254          */
 255         if (!READ_ONCE(icmp_global.credit)) {
 256                 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
 257                 if (delta < HZ / 50)
 258                         return false;
 259         }
 260
 261         spin_lock(&icmp_global.lock);
 262         delta = min_t(u32, now - icmp_global.stamp, HZ);
 263         if (delta >= HZ / 50) {
 264                 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
 265                 if (incr)
 266                         WRITE_ONCE(icmp_global.stamp, now);
 267         }
 268         credit = min_t(u32, icmp_global.credit + incr,
 269                        READ_ONCE(sysctl_icmp_msgs_burst));
 270         if (credit) {
 271                 /* We want to use a credit of one in average, but need to randomize
 272                  * it for security reasons.
 273                  */
 274                 credit = max_t(int, credit - prandom_u32_max(3), 0);
 275                 rc = true;
 276         }
 277         WRITE_ONCE(icmp_global.credit, credit);
 278         spin_unlock(&icmp_global.lock);
 279         return rc;
 280 }
 281 EXPORT_SYMBOL(icmp_global_allow);
 282
 283 static bool icmpv4_mask_allow(struct net *net, int type, int code)
 284 {
 285         if (type > NR_ICMP_TYPES)
 286                 return true;
 287
 288         /* Don't limit PMTU discovery. */
 289         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 290                 return true;
 291
 292         /* Limit if icmp type is enabled in ratemask. */
 293         if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
 294                 return true;
 295
 296         return false;
 297 }
 298
 299 static bool icmpv4_global_allow(struct net *net, int type, int code)
 300 {
 301         if (icmpv4_mask_allow(net, type, code))
 302                 return true;
 303
 304         if (icmp_global_allow())
 305                 return true;
 306
 307         return false;
 308 }
 309
 310 /*
 311  *      Send an ICMP frame.
 312  */
 313
 314 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 315                                struct flowi4 *fl4, int type, int code)
 316 {
 317         struct dst_entry *dst = &rt->dst;
 318         struct inet_peer *peer;
 319         bool rc = true;
 320         int vif;
 321
 322         if (icmpv4_mask_allow(net, type, code))
 323                 goto out;
 324
 325         /* No rate limit on loopback */
 326         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 327                 goto out;
 328
 329         vif = l3mdev_master_ifindex(dst->dev);
 330         peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
 331         rc = inet_peer_xrlim_allow(peer,
 332                                    READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
 333         if (peer)
 334                 inet_putpeer(peer);
 335 out:
 336         return rc;
 337 }
 338
 339 /*
 340  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 341  */
 342 void icmp_out_count(struct net *net, unsigned char type)
 343 {
 344         ICMPMSGOUT_INC_STATS(net, type);
 345         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 346 }
 347
 348 /*
 349  *      Checksum each fragment, and on the first include the headers and final
 350  *      checksum.
 351  */
 352 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 353                           struct sk_buff *skb)
 354 {
 355         struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
 356         __wsum csum;
 357
 358         csum = skb_copy_and_csum_bits(icmp_param->skb,
 359                                       icmp_param->offset + offset,
 360                                       to, len);
 361
 362         skb->csum = csum_block_add(skb->csum, csum, odd);
 363         if (icmp_pointers[icmp_param->data.icmph.type].error)
 364                 nf_ct_attach(skb, icmp_param->skb);
 365         return 0;
 366 }
 367
 368 static void icmp_push_reply(struct icmp_bxm *icmp_param,
 369                             struct flowi4 *fl4,
 370                             struct ipcm_cookie *ipc, struct rtable **rt)
 371 {
 372         struct sock *sk;
 373         struct sk_buff *skb;
 374
 375         sk = icmp_sk(dev_net((*rt)->dst.dev));
 376         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 377                            icmp_param->data_len+icmp_param->head_len,
 378                            icmp_param->head_len,
 379                            ipc, rt, MSG_DONTWAIT) < 0) {
 380                 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
 381                 ip_flush_pending_frames(sk);
 382         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 383                 struct icmphdr *icmph = icmp_hdr(skb);
 384                 __wsum csum;
 385                 struct sk_buff *skb1;
 386
 387                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 388                                                  (char *)icmph,
 389                                                  icmp_param->head_len);
 390                 skb_queue_walk(&sk->sk_write_queue, skb1) {
 391                         csum = csum_add(csum, skb1->csum);
 392                 }
 393                 icmph->checksum = csum_fold(csum);
 394                 skb->ip_summed = CHECKSUM_NONE;
 395                 ip_push_pending_frames(sk, fl4);
 396         }
 397 }
 398
 399 /*
 400  *      Driving logic for building and sending ICMP messages.
 401  */
 402
 403 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 404 {
 405         struct ipcm_cookie ipc;
 406         struct rtable *rt = skb_rtable(skb);
 407         struct net *net = dev_net(rt->dst.dev);
 408         struct flowi4 fl4;
 409         struct sock *sk;
 410         struct inet_sock *inet;
 411         __be32 daddr, saddr;
 412         u32 mark = IP4_REPLY_MARK(net, skb->mark);
 413         int type = icmp_param->data.icmph.type;
 414         int code = icmp_param->data.icmph.code;
 415
 416         if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
 417                 return;
 418
 419         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 420         local_bh_disable();
 421
 422         /* global icmp_msgs_per_sec */
 423         if (!icmpv4_global_allow(net, type, code))
 424                 goto out_bh_enable;
 425
 426         sk = icmp_xmit_lock(net);
 427         if (!sk)
 428                 goto out_bh_enable;
 429         inet = inet_sk(sk);
 430
 431         icmp_param->data.icmph.checksum = 0;
 432
 433         ipcm_init(&ipc);
 434         inet->tos = ip_hdr(skb)->tos;
 435         ipc.sockc.mark = mark;
 436         daddr = ipc.addr = ip_hdr(skb)->saddr;
 437         saddr = fib_compute_spec_dst(skb);
 438
 439         if (icmp_param->replyopts.opt.opt.optlen) {
 440                 ipc.opt = &icmp_param->replyopts.opt;
 441                 if (ipc.opt->opt.srr)
 442                         daddr = icmp_param->replyopts.opt.opt.faddr;
 443         }
 444         memset(&fl4, 0, sizeof(fl4));
 445         fl4.daddr = daddr;
 446         fl4.saddr = saddr;
 447         fl4.flowi4_mark = mark;
 448         fl4.flowi4_uid = sock_net_uid(net, NULL);
 449         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 450         fl4.flowi4_proto = IPPROTO_ICMP;
 451         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 452         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 453         rt = ip_route_output_key(net, &fl4);
 454         if (IS_ERR(rt))
 455                 goto out_unlock;
 456         if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 457                 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
 458         ip_rt_put(rt);
 459 out_unlock:
 460         icmp_xmit_unlock(sk);
 461 out_bh_enable:
 462         local_bh_enable();
 463 }
 464
 465 /*
 466  * The device used for looking up which routing table to use for sending an ICMP
 467  * error is preferably the source whenever it is set, which should ensure the
 468  * icmp error can be sent to the source host, else lookup using the routing
 469  * table of the destination device, else use the main routing table (index 0).
 470  */
 471 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
 472 {
 473         struct net_device *route_lookup_dev = NULL;
 474
 475         if (skb->dev)
 476                 route_lookup_dev = skb->dev;
 477         else if (skb_dst(skb))
 478                 route_lookup_dev = skb_dst(skb)->dev;
 479         return route_lookup_dev;
 480 }
 481
 482 static struct rtable *icmp_route_lookup(struct net *net,
 483                                         struct flowi4 *fl4,
 484                                         struct sk_buff *skb_in,
 485                                         const struct iphdr *iph,
 486                                         __be32 saddr, u8 tos, u32 mark,
 487                                         int type, int code,
 488                                         struct icmp_bxm *param)
 489 {
 490         struct net_device *route_lookup_dev;
 491         struct rtable *rt, *rt2;
 492         struct flowi4 fl4_dec;
 493         int err;
 494
 495         memset(fl4, 0, sizeof(*fl4));
 496         fl4->daddr = (param->replyopts.opt.opt.srr ?
 497                       param->replyopts.opt.opt.faddr : iph->saddr);
 498         fl4->saddr = saddr;
 499         fl4->flowi4_mark = mark;
 500         fl4->flowi4_uid = sock_net_uid(net, NULL);
 501         fl4->flowi4_tos = RT_TOS(tos);
 502         fl4->flowi4_proto = IPPROTO_ICMP;
 503         fl4->fl4_icmp_type = type;
 504         fl4->fl4_icmp_code = code;
 505         route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
 506         fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
 507
 508         security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
 509         rt = ip_route_output_key_hash(net, fl4, skb_in);
 510         if (IS_ERR(rt))
 511                 return rt;
 512
 513         /* No need to clone since we're just using its address. */
 514         rt2 = rt;
 515
 516         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 517                                            flowi4_to_flowi(fl4), NULL, 0);
 518         if (!IS_ERR(rt)) {
 519                 if (rt != rt2)
 520                         return rt;
 521         } else if (PTR_ERR(rt) == -EPERM) {
 522                 rt = NULL;
 523         } else
 524                 return rt;
 525
 526         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 527         if (err)
 528                 goto relookup_failed;
 529
 530         if (inet_addr_type_dev_table(net, route_lookup_dev,
 531                                      fl4_dec.saddr) == RTN_LOCAL) {
 532                 rt2 = __ip_route_output_key(net, &fl4_dec);
 533                 if (IS_ERR(rt2))
 534                         err = PTR_ERR(rt2);
 535         } else {
 536                 struct flowi4 fl4_2 = {};
 537                 unsigned long orefdst;
 538
 539                 fl4_2.daddr = fl4_dec.saddr;
 540                 rt2 = ip_route_output_key(net, &fl4_2);
 541                 if (IS_ERR(rt2)) {
 542                         err = PTR_ERR(rt2);
 543                         goto relookup_failed;
 544                 }
 545                 /* Ugh! */
 546                 orefdst = skb_in->_skb_refdst; /* save old refdst */
 547                 skb_dst_set(skb_in, NULL);
 548                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 549                                      RT_TOS(tos), rt2->dst.dev);
 550
 551                 dst_release(&rt2->dst);
 552                 rt2 = skb_rtable(skb_in);
 553                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
 554         }
 555
 556         if (err)
 557                 goto relookup_failed;
 558
 559         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 560                                             flowi4_to_flowi(&fl4_dec), NULL,
 561                                             XFRM_LOOKUP_ICMP);
 562         if (!IS_ERR(rt2)) {
 563                 dst_release(&rt->dst);
 564                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
 565                 rt = rt2;
 566         } else if (PTR_ERR(rt2) == -EPERM) {
 567                 if (rt)
 568                         dst_release(&rt->dst);
 569                 return rt2;
 570         } else {
 571                 err = PTR_ERR(rt2);
 572                 goto relookup_failed;
 573         }
 574         return rt;
 575
 576 relookup_failed:
 577         if (rt)
 578                 return rt;
 579         return ERR_PTR(err);
 580 }
 581
 582 /*
 583  *      Send an ICMP message in response to a situation
 584  *
 585  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 586  *                MAY send more (we do).
 587  *                      MUST NOT change this header information.
 588  *                      MUST NOT reply to a multicast/broadcast IP address.
 589  *                      MUST NOT reply to a multicast/broadcast MAC address.
 590  *                      MUST reply to only the first fragment.
 591  */
 592
 593 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 594                  const struct ip_options *opt)
 595 {
 596         struct iphdr *iph;
 597         int room;
 598         struct icmp_bxm icmp_param;
 599         struct rtable *rt = skb_rtable(skb_in);
 600         struct ipcm_cookie ipc;
 601         struct flowi4 fl4;
 602         __be32 saddr;
 603         u8  tos;
 604         u32 mark;
 605         struct net *net;
 606         struct sock *sk;
 607
 608         if (!rt)
 609                 goto out;
 610
 611         if (rt->dst.dev)
 612                 net = dev_net(rt->dst.dev);
 613         else if (skb_in->dev)
 614                 net = dev_net(skb_in->dev);
 615         else
 616                 goto out;
 617
 618         /*
 619          *      Find the original header. It is expected to be valid, of course.
 620          *      Check this, icmp_send is called from the most obscure devices
 621          *      sometimes.
 622          */
 623         iph = ip_hdr(skb_in);
 624
 625         if ((u8 *)iph < skb_in->head ||
 626             (skb_network_header(skb_in) + sizeof(*iph)) >
 627             skb_tail_pointer(skb_in))
 628                 goto out;
 629
 630         /*
 631          *      No replies to physical multicast/broadcast
 632          */
 633         if (skb_in->pkt_type != PACKET_HOST)
 634                 goto out;
 635
 636         /*
 637          *      Now check at the protocol level
 638          */
 639         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 640                 goto out;
 641
 642         /*
 643          *      Only reply to fragment 0. We byte re-order the constant
 644          *      mask for efficiency.
 645          */
 646         if (iph->frag_off & htons(IP_OFFSET))
 647                 goto out;
 648
 649         /*
 650          *      If we send an ICMP error to an ICMP error a mess would result..
 651          */
 652         if (icmp_pointers[type].error) {
 653                 /*
 654                  *      We are an error, check if we are replying to an
 655                  *      ICMP error
 656                  */
 657                 if (iph->protocol == IPPROTO_ICMP) {
 658                         u8 _inner_type, *itp;
 659
 660                         itp = skb_header_pointer(skb_in,
 661                                                  skb_network_header(skb_in) +
 662                                                  (iph->ihl << 2) +
 663                                                  offsetof(struct icmphdr,
 664                                                           type) -
 665                                                  skb_in->data,
 666                                                  sizeof(_inner_type),
 667                                                  &_inner_type);
 668                         if (!itp)
 669                                 goto out;
 670
 671                         /*
 672                          *      Assume any unknown ICMP type is an error. This
 673                          *      isn't specified by the RFC, but think about it..
 674                          */
 675                         if (*itp > NR_ICMP_TYPES ||
 676                             icmp_pointers[*itp].error)
 677                                 goto out;
 678                 }
 679         }
 680
 681         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 682         local_bh_disable();
 683
 684         /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
 685          * incoming dev is loopback.  If outgoing dev change to not be
 686          * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
 687          */
 688         if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
 689               !icmpv4_global_allow(net, type, code))
 690                 goto out_bh_enable;
 691
 692         sk = icmp_xmit_lock(net);
 693         if (!sk)
 694                 goto out_bh_enable;
 695
 696         /*
 697          *      Construct source address and options.
 698          */
 699
 700         saddr = iph->daddr;
 701         if (!(rt->rt_flags & RTCF_LOCAL)) {
 702                 struct net_device *dev = NULL;
 703
 704                 rcu_read_lock();
 705                 if (rt_is_input_route(rt) &&
 706                     READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
 707                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 708
 709                 if (dev)
 710                         saddr = inet_select_addr(dev, iph->saddr,
 711                                                  RT_SCOPE_LINK);
 712                 else
 713                         saddr = 0;
 714                 rcu_read_unlock();
 715         }
 716
 717         tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
 718                                            IPTOS_PREC_INTERNETCONTROL) :
 719                                            iph->tos;
 720         mark = IP4_REPLY_MARK(net, skb_in->mark);
 721
 722         if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
 723                 goto out_unlock;
 724
 725
 726         /*
 727          *      Prepare data for ICMP header.
 728          */
 729
 730         icmp_param.data.icmph.type       = type;
 731         icmp_param.data.icmph.code       = code;
 732         icmp_param.data.icmph.un.gateway = info;
 733         icmp_param.data.icmph.checksum   = 0;
 734         icmp_param.skb    = skb_in;
 735         icmp_param.offset = skb_network_offset(skb_in);
 736         inet_sk(sk)->tos = tos;
 737         ipcm_init(&ipc);
 738         ipc.addr = iph->saddr;
 739         ipc.opt = &icmp_param.replyopts.opt;
 740         ipc.sockc.mark = mark;
 741
 742         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 743                                type, code, &icmp_param);
 744         if (IS_ERR(rt))
 745                 goto out_unlock;
 746
 747         /* peer icmp_ratelimit */
 748         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 749                 goto ende;
 750
 751         /* RFC says return as much as we can without exceeding 576 bytes. */
 752
 753         room = dst_mtu(&rt->dst);
 754         if (room > 576)
 755                 room = 576;
 756         room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 757         room -= sizeof(struct icmphdr);
 758         /* Guard against tiny mtu. We need to include at least one
 759          * IP network header for this message to make any sense.
 760          */
 761         if (room <= (int)sizeof(struct iphdr))
 762                 goto ende;
 763
 764         icmp_param.data_len = skb_in->len - icmp_param.offset;
 765         if (icmp_param.data_len > room)
 766                 icmp_param.data_len = room;
 767         icmp_param.head_len = sizeof(struct icmphdr);
 768
 769         /* if we don't have a source address at this point, fall back to the
 770          * dummy address instead of sending out a packet with a source address
 771          * of 0.0.0.0
 772          */
 773         if (!fl4.saddr)
 774                 fl4.saddr = htonl(INADDR_DUMMY);
 775
 776         icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
 777 ende:
 778         ip_rt_put(rt);
 779 out_unlock:
 780         icmp_xmit_unlock(sk);
 781 out_bh_enable:
 782         local_bh_enable();
 783 out:;
 784 }
 785 EXPORT_SYMBOL(__icmp_send);
 786
 787 #if IS_ENABLED(CONFIG_NF_NAT)
 788 #include <net/netfilter/nf_conntrack.h>
 789 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 790 {
 791         struct sk_buff *cloned_skb = NULL;
 792         struct ip_options opts = { 0 };
 793         enum ip_conntrack_info ctinfo;
 794         struct nf_conn *ct;
 795         __be32 orig_ip;
 796
 797         ct = nf_ct_get(skb_in, &ctinfo);
 798         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 799                 __icmp_send(skb_in, type, code, info, &opts);
 800                 return;
 801         }
 802
 803         if (skb_shared(skb_in))
 804                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 805
 806         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 807             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 808             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 809             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 810                 goto out;
 811
 812         orig_ip = ip_hdr(skb_in)->saddr;
 813         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 814         __icmp_send(skb_in, type, code, info, &opts);
 815         ip_hdr(skb_in)->saddr = orig_ip;
 816 out:
 817         consume_skb(cloned_skb);
 818 }
 819 EXPORT_SYMBOL(icmp_ndo_send);
 820 #endif
 821
 822 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 823 {
 824         const struct iphdr *iph = (const struct iphdr *)skb->data;
 825         const struct net_protocol *ipprot;
 826         int protocol = iph->protocol;
 827
 828         /* Checkin full IP header plus 8 bytes of protocol to
 829          * avoid additional coding at protocol handlers.
 830          */
 831         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 832                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 833                 return;
 834         }
 835
 836         raw_icmp_error(skb, protocol, info);
 837
 838         ipprot = rcu_dereference(inet_protos[protocol]);
 839         if (ipprot && ipprot->err_handler)
 840                 ipprot->err_handler(skb, info);
 841 }
 842
 843 static bool icmp_tag_validation(int proto)
 844 {
 845         bool ok;
 846
 847         rcu_read_lock();
 848         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 849         rcu_read_unlock();
 850         return ok;
 851 }
 852
 853 /*
 854  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 855  *      ICMP_PARAMETERPROB.
 856  */
 857
 858 static bool icmp_unreach(struct sk_buff *skb)
 859 {
 860         const struct iphdr *iph;
 861         struct icmphdr *icmph;
 862         struct net *net;
 863         u32 info = 0;
 864
 865         net = dev_net(skb_dst(skb)->dev);
 866
 867         /*
 868          *      Incomplete header ?
 869          *      Only checks for the IP header, there should be an
 870          *      additional check for longer headers in upper levels.
 871          */
 872
 873         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 874                 goto out_err;
 875
 876         icmph = icmp_hdr(skb);
 877         iph   = (const struct iphdr *)skb->data;
 878
 879         if (iph->ihl < 5) /* Mangled header, drop. */
 880                 goto out_err;
 881
 882         switch (icmph->type) {
 883         case ICMP_DEST_UNREACH:
 884                 switch (icmph->code & 15) {
 885                 case ICMP_NET_UNREACH:
 886                 case ICMP_HOST_UNREACH:
 887                 case ICMP_PROT_UNREACH:
 888                 case ICMP_PORT_UNREACH:
 889                         break;
 890                 case ICMP_FRAG_NEEDED:
 891                         /* for documentation of the ip_no_pmtu_disc
 892                          * values please see
 893                          * Documentation/networking/ip-sysctl.rst
 894                          */
 895                         switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
 896                         default:
 897                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 898                                                     &iph->daddr);
 899                                 break;
 900                         case 2:
 901                                 goto out;
 902                         case 3:
 903                                 if (!icmp_tag_validation(iph->protocol))
 904                                         goto out;
 905                                 fallthrough;
 906                         case 0:
 907                                 info = ntohs(icmph->un.frag.mtu);
 908                         }
 909                         break;
 910                 case ICMP_SR_FAILED:
 911                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 912                                             &iph->daddr);
 913                         break;
 914                 default:
 915                         break;
 916                 }
 917                 if (icmph->code > NR_ICMP_UNREACH)
 918                         goto out;
 919                 break;
 920         case ICMP_PARAMETERPROB:
 921                 info = ntohl(icmph->un.gateway) >> 24;
 922                 break;
 923         case ICMP_TIME_EXCEEDED:
 924                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 925                 if (icmph->code == ICMP_EXC_FRAGTIME)
 926                         goto out;
 927                 break;
 928         }
 929
 930         /*
 931          *      Throw it at our lower layers
 932          *
 933          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 934          *                header.
 935          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 936          *                transport layer.
 937          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 938          *                transport layer.
 939          */
 940
 941         /*
 942          *      Check the other end isn't violating RFC 1122. Some routers send
 943          *      bogus responses to broadcast frames. If you see this message
 944          *      first check your netmask matches at both ends, if it does then
 945          *      get the other vendor to fix their kit.
 946          */
 947
 948         if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
 949             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 950                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 951                                      &ip_hdr(skb)->saddr,
 952                                      icmph->type, icmph->code,
 953                                      &iph->daddr, skb->dev->name);
 954                 goto out;
 955         }
 956
 957         icmp_socket_deliver(skb, info);
 958
 959 out:
 960         return true;
 961 out_err:
 962         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 963         return false;
 964 }
 965
 966
 967 /*
 968  *      Handle ICMP_REDIRECT.
 969  */
 970
 971 static bool icmp_redirect(struct sk_buff *skb)
 972 {
 973         if (skb->len < sizeof(struct iphdr)) {
 974                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 975                 return false;
 976         }
 977
 978         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 979                 /* there aught to be a stat */
 980                 return false;
 981         }
 982
 983         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 984         return true;
 985 }
 986
 987 /*
 988  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 989  *
 990  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 991  *                requests.
 992  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 993  *                included in the reply.
 994  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 995  *                echo requests, MUST have default=NOT.
 996  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 997  *                Extended Echo Functionality, MUST be disabled by default
 998  *      See also WRT handling of options once they are done and working.
 999  */
1000
1001 static bool icmp_echo(struct sk_buff *skb)
1002 {
1003         struct icmp_bxm icmp_param;
1004         struct net *net;
1005
1006         net = dev_net(skb_dst(skb)->dev);
1007         /* should there be an ICMP stat for ignored echos? */
1008         if (net->ipv4.sysctl_icmp_echo_ignore_all)
1009                 return true;
1010
1011         icmp_param.data.icmph      = *icmp_hdr(skb);
1012         icmp_param.skb             = skb;
1013         icmp_param.offset          = 0;
1014         icmp_param.data_len        = skb->len;
1015         icmp_param.head_len        = sizeof(struct icmphdr);
1016
1017         if (icmp_param.data.icmph.type == ICMP_ECHO)
1018                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1019         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1020                 return true;
1021
1022         icmp_reply(&icmp_param, skb);
1023         return true;
1024 }
1025
1026 /*      Helper for icmp_echo and icmpv6_echo_reply.
1027  *      Searches for net_device that matches PROBE interface identifier
1028  *              and builds PROBE reply message in icmphdr.
1029  *
1030  *      Returns false if PROBE responses are disabled via sysctl
1031  */
1032
1033 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1034 {
1035         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1036         struct icmp_ext_echo_iio *iio, _iio;
1037         struct net *net = dev_net(skb->dev);
1038         struct net_device *dev;
1039         char buff[IFNAMSIZ];
1040         u16 ident_len;
1041         u8 status;
1042
1043         if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1044                 return false;
1045
1046         /* We currently only support probing interfaces on the proxy node
1047          * Check to ensure L-bit is set
1048          */
1049         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1050                 return false;
1051         /* Clear status bits in reply message */
1052         icmphdr->un.echo.sequence &= htons(0xFF00);
1053         if (icmphdr->type == ICMP_EXT_ECHO)
1054                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1055         else
1056                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1057         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1058         /* Size of iio is class_type dependent.
1059          * Only check header here and assign length based on ctype in the switch statement
1060          */
1061         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1062         if (!ext_hdr || !iio)
1063                 goto send_mal_query;
1064         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1065             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1066                 goto send_mal_query;
1067         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1068         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1069                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1070         if (!iio)
1071                 goto send_mal_query;
1072
1073         status = 0;
1074         dev = NULL;
1075         switch (iio->extobj_hdr.class_type) {
1076         case ICMP_EXT_ECHO_CTYPE_NAME:
1077                 if (ident_len >= IFNAMSIZ)
1078                         goto send_mal_query;
1079                 memset(buff, 0, sizeof(buff));
1080                 memcpy(buff, &iio->ident.name, ident_len);
1081                 dev = dev_get_by_name(net, buff);
1082                 break;
1083         case ICMP_EXT_ECHO_CTYPE_INDEX:
1084                 if (ident_len != sizeof(iio->ident.ifindex))
1085                         goto send_mal_query;
1086                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1087                 break;
1088         case ICMP_EXT_ECHO_CTYPE_ADDR:
1089                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1090                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1091                                  iio->ident.addr.ctype3_hdr.addrlen)
1092                         goto send_mal_query;
1093                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1094                 case ICMP_AFI_IP:
1095                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1096                                 goto send_mal_query;
1097                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1098                         break;
1099 #if IS_ENABLED(CONFIG_IPV6)
1100                 case ICMP_AFI_IP6:
1101                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1102                                 goto send_mal_query;
1103                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1104                         dev_hold(dev);
1105                         break;
1106 #endif
1107                 default:
1108                         goto send_mal_query;
1109                 }
1110                 break;
1111         default:
1112                 goto send_mal_query;
1113         }
1114         if (!dev) {
1115                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1116                 return true;
1117         }
1118         /* Fill bits in reply message */
1119         if (dev->flags & IFF_UP)
1120                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1121         if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1122                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1123         if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1124                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1125         dev_put(dev);
1126         icmphdr->un.echo.sequence |= htons(status);
1127         return true;
1128 send_mal_query:
1129         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1130         return true;
1131 }
1132 EXPORT_SYMBOL_GPL(icmp_build_probe);
1133
1134 /*
1135  *      Handle ICMP Timestamp requests.
1136  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1137  *                SHOULD be in the kernel for minimum random latency.
1138  *                MUST be accurate to a few minutes.
1139  *                MUST be updated at least at 15Hz.
1140  */
1141 static bool icmp_timestamp(struct sk_buff *skb)
1142 {
1143         struct icmp_bxm icmp_param;
1144         /*
1145          *      Too short.
1146          */
1147         if (skb->len < 4)
1148                 goto out_err;
1149
1150         /*
1151          *      Fill in the current time as ms since midnight UT:
1152          */
1153         icmp_param.data.times[1] = inet_current_timestamp();
1154         icmp_param.data.times[2] = icmp_param.data.times[1];
1155
1156         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1157
1158         icmp_param.data.icmph      = *icmp_hdr(skb);
1159         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1160         icmp_param.data.icmph.code = 0;
1161         icmp_param.skb             = skb;
1162         icmp_param.offset          = 0;
1163         icmp_param.data_len        = 0;
1164         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1165         icmp_reply(&icmp_param, skb);
1166         return true;
1167
1168 out_err:
1169         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1170         return false;
1171 }
1172
1173 static bool icmp_discard(struct sk_buff *skb)
1174 {
1175         /* pretend it was a success */
1176         return true;
1177 }
1178
1179 /*
1180  *      Deal with incoming ICMP packets.
1181  */
1182 int icmp_rcv(struct sk_buff *skb)
1183 {
1184         struct icmphdr *icmph;
1185         struct rtable *rt = skb_rtable(skb);
1186         struct net *net = dev_net(rt->dst.dev);
1187         bool success;
1188
1189         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1190                 struct sec_path *sp = skb_sec_path(skb);
1191                 int nh;
1192
1193                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1194                                  XFRM_STATE_ICMP))
1195                         goto drop;
1196
1197                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1198                         goto drop;
1199
1200                 nh = skb_network_offset(skb);
1201                 skb_set_network_header(skb, sizeof(*icmph));
1202
1203                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1204                         goto drop;
1205
1206                 skb_set_network_header(skb, nh);
1207         }
1208
1209         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1210
1211         if (skb_checksum_simple_validate(skb))
1212                 goto csum_error;
1213
1214         if (!pskb_pull(skb, sizeof(*icmph)))
1215                 goto error;
1216
1217         icmph = icmp_hdr(skb);
1218
1219         ICMPMSGIN_INC_STATS(net, icmph->type);
1220
1221         /* Check for ICMP Extended Echo (PROBE) messages */
1222         if (icmph->type == ICMP_EXT_ECHO) {
1223                 /* We can't use icmp_pointers[].handler() because it is an array of
1224                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1225                  */
1226                 success = icmp_echo(skb);
1227                 goto success_check;
1228         }
1229
1230         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1231                 success = ping_rcv(skb);
1232                 goto success_check;
1233         }
1234
1235         /*
1236          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1237          *
1238          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1239          *                discarded.
1240          */
1241         if (icmph->type > NR_ICMP_TYPES)
1242                 goto error;
1243
1244         /*
1245          *      Parse the ICMP message
1246          */
1247
1248         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1249                 /*
1250                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1251                  *        silently ignored (we let user decide with a sysctl).
1252                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1253                  *        discarded if to broadcast/multicast.
1254                  */
1255                 if ((icmph->type == ICMP_ECHO ||
1256                      icmph->type == ICMP_TIMESTAMP) &&
1257                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1258                         goto error;
1259                 }
1260                 if (icmph->type != ICMP_ECHO &&
1261                     icmph->type != ICMP_TIMESTAMP &&
1262                     icmph->type != ICMP_ADDRESS &&
1263                     icmph->type != ICMP_ADDRESSREPLY) {
1264                         goto error;
1265                 }
1266         }
1267
1268         success = icmp_pointers[icmph->type].handler(skb);
1269 success_check:
1270         if (success)  {
1271                 consume_skb(skb);
1272                 return NET_RX_SUCCESS;
1273         }
1274
1275 drop:
1276         kfree_skb(skb);
1277         return NET_RX_DROP;
1278 csum_error:
1279         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1280 error:
1281         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1282         goto drop;
1283 }
1284
1285 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1286 {
1287         struct icmp_extobj_hdr *objh, _objh;
1288         struct icmp_ext_hdr *exth, _exth;
1289         u16 olen;
1290
1291         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1292         if (!exth)
1293                 return false;
1294         if (exth->version != 2)
1295                 return true;
1296
1297         if (exth->checksum &&
1298             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1299                 return false;
1300
1301         off += sizeof(_exth);
1302         while (off < skb->len) {
1303                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1304                 if (!objh)
1305                         return false;
1306
1307                 olen = ntohs(objh->length);
1308                 if (olen < sizeof(_objh))
1309                         return false;
1310
1311                 off += olen;
1312                 if (off > skb->len)
1313                         return false;
1314         }
1315
1316         return true;
1317 }
1318
1319 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1320                            struct sock_ee_data_rfc4884 *out,
1321                            int thlen, int off)
1322 {
1323         int hlen;
1324
1325         /* original datagram headers: end of icmph to payload (skb->data) */
1326         hlen = -skb_transport_offset(skb) - thlen;
1327
1328         /* per rfc 4884: minimal datagram length of 128 bytes */
1329         if (off < 128 || off < hlen)
1330                 return;
1331
1332         /* kernel has stripped headers: return payload offset in bytes */
1333         off -= hlen;
1334         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1335                 return;
1336
1337         out->len = off;
1338
1339         if (!ip_icmp_error_rfc4884_validate(skb, off))
1340                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1341 }
1342 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1343
1344 int icmp_err(struct sk_buff *skb, u32 info)
1345 {
1346         struct iphdr *iph = (struct iphdr *)skb->data;
1347         int offset = iph->ihl<<2;
1348         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1349         int type = icmp_hdr(skb)->type;
1350         int code = icmp_hdr(skb)->code;
1351         struct net *net = dev_net(skb->dev);
1352
1353         /*
1354          * Use ping_err to handle all icmp errors except those
1355          * triggered by ICMP_ECHOREPLY which sent from kernel.
1356          */
1357         if (icmph->type != ICMP_ECHOREPLY) {
1358                 ping_err(skb, offset, info);
1359                 return 0;
1360         }
1361
1362         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1363                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1364         else if (type == ICMP_REDIRECT)
1365                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1366
1367         return 0;
1368 }
1369
1370 /*
1371  *      This table is the definition of how we handle ICMP.
1372  */
1373 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1374         [ICMP_ECHOREPLY] = {
1375                 .handler = ping_rcv,
1376         },
1377         [1] = {
1378                 .handler = icmp_discard,
1379                 .error = 1,
1380         },
1381         [2] = {
1382                 .handler = icmp_discard,
1383                 .error = 1,
1384         },
1385         [ICMP_DEST_UNREACH] = {
1386                 .handler = icmp_unreach,
1387                 .error = 1,
1388         },
1389         [ICMP_SOURCE_QUENCH] = {
1390                 .handler = icmp_unreach,
1391                 .error = 1,
1392         },
1393         [ICMP_REDIRECT] = {
1394                 .handler = icmp_redirect,
1395                 .error = 1,
1396         },
1397         [6] = {
1398                 .handler = icmp_discard,
1399                 .error = 1,
1400         },
1401         [7] = {
1402                 .handler = icmp_discard,
1403                 .error = 1,
1404         },
1405         [ICMP_ECHO] = {
1406                 .handler = icmp_echo,
1407         },
1408         [9] = {
1409                 .handler = icmp_discard,
1410                 .error = 1,
1411         },
1412         [10] = {
1413                 .handler = icmp_discard,
1414                 .error = 1,
1415         },
1416         [ICMP_TIME_EXCEEDED] = {
1417                 .handler = icmp_unreach,
1418                 .error = 1,
1419         },
1420         [ICMP_PARAMETERPROB] = {
1421                 .handler = icmp_unreach,
1422                 .error = 1,
1423         },
1424         [ICMP_TIMESTAMP] = {
1425                 .handler = icmp_timestamp,
1426         },
1427         [ICMP_TIMESTAMPREPLY] = {
1428                 .handler = icmp_discard,
1429         },
1430         [ICMP_INFO_REQUEST] = {
1431                 .handler = icmp_discard,
1432         },
1433         [ICMP_INFO_REPLY] = {
1434                 .handler = icmp_discard,
1435         },
1436         [ICMP_ADDRESS] = {
1437                 .handler = icmp_discard,
1438         },
1439         [ICMP_ADDRESSREPLY] = {
1440                 .handler = icmp_discard,
1441         },
1442 };
1443
1444 static void __net_exit icmp_sk_exit(struct net *net)
1445 {
1446         int i;
1447
1448         for_each_possible_cpu(i)
1449                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1450         free_percpu(net->ipv4.icmp_sk);
1451         net->ipv4.icmp_sk = NULL;
1452 }
1453
1454 static int __net_init icmp_sk_init(struct net *net)
1455 {
1456         int i, err;
1457
1458         net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1459         if (!net->ipv4.icmp_sk)
1460                 return -ENOMEM;
1461
1462         for_each_possible_cpu(i) {
1463                 struct sock *sk;
1464
1465                 err = inet_ctl_sock_create(&sk, PF_INET,
1466                                            SOCK_RAW, IPPROTO_ICMP, net);
1467                 if (err < 0)
1468                         goto fail;
1469
1470                 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1471
1472                 /* Enough space for 2 64K ICMP packets, including
1473                  * sk_buff/skb_shared_info struct overhead.
1474                  */
1475                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1476
1477                 /*
1478                  * Speedup sock_wfree()
1479                  */
1480                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1481                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1482         }
1483
1484         /* Control parameters for ECHO replies. */
1485         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1486         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1487         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1488
1489         /* Control parameter - ignore bogus broadcast responses? */
1490         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1491
1492         /*
1493          *      Configurable global rate limit.
1494          *
1495          *      ratelimit defines tokens/packet consumed for dst->rate_token
1496          *      bucket ratemask defines which icmp types are ratelimited by
1497          *      setting it's bit position.
1498          *
1499          *      default:
1500          *      dest unreachable (3), source quench (4),
1501          *      time exceeded (11), parameter problem (12)
1502          */
1503
1504         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1505         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1506         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1507
1508         return 0;
1509
1510 fail:
1511         icmp_sk_exit(net);
1512         return err;
1513 }
1514
1515 static struct pernet_operations __net_initdata icmp_sk_ops = {
1516        .init = icmp_sk_init,
1517        .exit = icmp_sk_exit,
1518 };
1519
1520 int __init icmp_init(void)
1521 {
1522         return register_pernet_subsys(&icmp_sk_ops);
1523 }