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
 759         icmp_param.data_len = skb_in->len - icmp_param.offset;
 760         if (icmp_param.data_len > room)
 761                 icmp_param.data_len = room;
 762         icmp_param.head_len = sizeof(struct icmphdr);
 763
 764         /* if we don't have a source address at this point, fall back to the
 765          * dummy address instead of sending out a packet with a source address
 766          * of 0.0.0.0
 767          */
 768         if (!fl4.saddr)
 769                 fl4.saddr = htonl(INADDR_DUMMY);
 770
 771         icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
 772 ende:
 773         ip_rt_put(rt);
 774 out_unlock:
 775         icmp_xmit_unlock(sk);
 776 out_bh_enable:
 777         local_bh_enable();
 778 out:;
 779 }
 780 EXPORT_SYMBOL(__icmp_send);
 781
 782 #if IS_ENABLED(CONFIG_NF_NAT)
 783 #include <net/netfilter/nf_conntrack.h>
 784 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 785 {
 786         struct sk_buff *cloned_skb = NULL;
 787         struct ip_options opts = { 0 };
 788         enum ip_conntrack_info ctinfo;
 789         struct nf_conn *ct;
 790         __be32 orig_ip;
 791
 792         ct = nf_ct_get(skb_in, &ctinfo);
 793         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 794                 __icmp_send(skb_in, type, code, info, &opts);
 795                 return;
 796         }
 797
 798         if (skb_shared(skb_in))
 799                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 800
 801         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 802             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 803             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 804             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 805                 goto out;
 806
 807         orig_ip = ip_hdr(skb_in)->saddr;
 808         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 809         __icmp_send(skb_in, type, code, info, &opts);
 810         ip_hdr(skb_in)->saddr = orig_ip;
 811 out:
 812         consume_skb(cloned_skb);
 813 }
 814 EXPORT_SYMBOL(icmp_ndo_send);
 815 #endif
 816
 817 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 818 {
 819         const struct iphdr *iph = (const struct iphdr *)skb->data;
 820         const struct net_protocol *ipprot;
 821         int protocol = iph->protocol;
 822
 823         /* Checkin full IP header plus 8 bytes of protocol to
 824          * avoid additional coding at protocol handlers.
 825          */
 826         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 827                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 828                 return;
 829         }
 830
 831         raw_icmp_error(skb, protocol, info);
 832
 833         ipprot = rcu_dereference(inet_protos[protocol]);
 834         if (ipprot && ipprot->err_handler)
 835                 ipprot->err_handler(skb, info);
 836 }
 837
 838 static bool icmp_tag_validation(int proto)
 839 {
 840         bool ok;
 841
 842         rcu_read_lock();
 843         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 844         rcu_read_unlock();
 845         return ok;
 846 }
 847
 848 /*
 849  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 850  *      ICMP_PARAMETERPROB.
 851  */
 852
 853 static bool icmp_unreach(struct sk_buff *skb)
 854 {
 855         const struct iphdr *iph;
 856         struct icmphdr *icmph;
 857         struct net *net;
 858         u32 info = 0;
 859
 860         net = dev_net(skb_dst(skb)->dev);
 861
 862         /*
 863          *      Incomplete header ?
 864          *      Only checks for the IP header, there should be an
 865          *      additional check for longer headers in upper levels.
 866          */
 867
 868         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 869                 goto out_err;
 870
 871         icmph = icmp_hdr(skb);
 872         iph   = (const struct iphdr *)skb->data;
 873
 874         if (iph->ihl < 5) /* Mangled header, drop. */
 875                 goto out_err;
 876
 877         switch (icmph->type) {
 878         case ICMP_DEST_UNREACH:
 879                 switch (icmph->code & 15) {
 880                 case ICMP_NET_UNREACH:
 881                 case ICMP_HOST_UNREACH:
 882                 case ICMP_PROT_UNREACH:
 883                 case ICMP_PORT_UNREACH:
 884                         break;
 885                 case ICMP_FRAG_NEEDED:
 886                         /* for documentation of the ip_no_pmtu_disc
 887                          * values please see
 888                          * Documentation/networking/ip-sysctl.rst
 889                          */
 890                         switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
 891                         default:
 892                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 893                                                     &iph->daddr);
 894                                 break;
 895                         case 2:
 896                                 goto out;
 897                         case 3:
 898                                 if (!icmp_tag_validation(iph->protocol))
 899                                         goto out;
 900                                 fallthrough;
 901                         case 0:
 902                                 info = ntohs(icmph->un.frag.mtu);
 903                         }
 904                         break;
 905                 case ICMP_SR_FAILED:
 906                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 907                                             &iph->daddr);
 908                         break;
 909                 default:
 910                         break;
 911                 }
 912                 if (icmph->code > NR_ICMP_UNREACH)
 913                         goto out;
 914                 break;
 915         case ICMP_PARAMETERPROB:
 916                 info = ntohl(icmph->un.gateway) >> 24;
 917                 break;
 918         case ICMP_TIME_EXCEEDED:
 919                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 920                 if (icmph->code == ICMP_EXC_FRAGTIME)
 921                         goto out;
 922                 break;
 923         }
 924
 925         /*
 926          *      Throw it at our lower layers
 927          *
 928          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 929          *                header.
 930          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 931          *                transport layer.
 932          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 933          *                transport layer.
 934          */
 935
 936         /*
 937          *      Check the other end isn't violating RFC 1122. Some routers send
 938          *      bogus responses to broadcast frames. If you see this message
 939          *      first check your netmask matches at both ends, if it does then
 940          *      get the other vendor to fix their kit.
 941          */
 942
 943         if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
 944             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 945                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 946                                      &ip_hdr(skb)->saddr,
 947                                      icmph->type, icmph->code,
 948                                      &iph->daddr, skb->dev->name);
 949                 goto out;
 950         }
 951
 952         icmp_socket_deliver(skb, info);
 953
 954 out:
 955         return true;
 956 out_err:
 957         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 958         return false;
 959 }
 960
 961
 962 /*
 963  *      Handle ICMP_REDIRECT.
 964  */
 965
 966 static bool icmp_redirect(struct sk_buff *skb)
 967 {
 968         if (skb->len < sizeof(struct iphdr)) {
 969                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 970                 return false;
 971         }
 972
 973         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 974                 /* there aught to be a stat */
 975                 return false;
 976         }
 977
 978         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 979         return true;
 980 }
 981
 982 /*
 983  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 984  *
 985  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 986  *                requests.
 987  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 988  *                included in the reply.
 989  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 990  *                echo requests, MUST have default=NOT.
 991  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 992  *                Extended Echo Functionality, MUST be disabled by default
 993  *      See also WRT handling of options once they are done and working.
 994  */
 995
 996 static bool icmp_echo(struct sk_buff *skb)
 997 {
 998         struct icmp_bxm icmp_param;
 999         struct net *net;
1000
1001         net = dev_net(skb_dst(skb)->dev);
1002         /* should there be an ICMP stat for ignored echos? */
1003         if (net->ipv4.sysctl_icmp_echo_ignore_all)
1004                 return true;
1005
1006         icmp_param.data.icmph      = *icmp_hdr(skb);
1007         icmp_param.skb             = skb;
1008         icmp_param.offset          = 0;
1009         icmp_param.data_len        = skb->len;
1010         icmp_param.head_len        = sizeof(struct icmphdr);
1011
1012         if (icmp_param.data.icmph.type == ICMP_ECHO)
1013                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1014         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1015                 return true;
1016
1017         icmp_reply(&icmp_param, skb);
1018         return true;
1019 }
1020
1021 /*      Helper for icmp_echo and icmpv6_echo_reply.
1022  *      Searches for net_device that matches PROBE interface identifier
1023  *              and builds PROBE reply message in icmphdr.
1024  *
1025  *      Returns false if PROBE responses are disabled via sysctl
1026  */
1027
1028 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1029 {
1030         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1031         struct icmp_ext_echo_iio *iio, _iio;
1032         struct net *net = dev_net(skb->dev);
1033         struct net_device *dev;
1034         char buff[IFNAMSIZ];
1035         u16 ident_len;
1036         u8 status;
1037
1038         if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1039                 return false;
1040
1041         /* We currently only support probing interfaces on the proxy node
1042          * Check to ensure L-bit is set
1043          */
1044         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1045                 return false;
1046         /* Clear status bits in reply message */
1047         icmphdr->un.echo.sequence &= htons(0xFF00);
1048         if (icmphdr->type == ICMP_EXT_ECHO)
1049                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1050         else
1051                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1052         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1053         /* Size of iio is class_type dependent.
1054          * Only check header here and assign length based on ctype in the switch statement
1055          */
1056         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1057         if (!ext_hdr || !iio)
1058                 goto send_mal_query;
1059         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1060             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1061                 goto send_mal_query;
1062         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1063         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1064                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1065         if (!iio)
1066                 goto send_mal_query;
1067
1068         status = 0;
1069         dev = NULL;
1070         switch (iio->extobj_hdr.class_type) {
1071         case ICMP_EXT_ECHO_CTYPE_NAME:
1072                 if (ident_len >= IFNAMSIZ)
1073                         goto send_mal_query;
1074                 memset(buff, 0, sizeof(buff));
1075                 memcpy(buff, &iio->ident.name, ident_len);
1076                 dev = dev_get_by_name(net, buff);
1077                 break;
1078         case ICMP_EXT_ECHO_CTYPE_INDEX:
1079                 if (ident_len != sizeof(iio->ident.ifindex))
1080                         goto send_mal_query;
1081                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1082                 break;
1083         case ICMP_EXT_ECHO_CTYPE_ADDR:
1084                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1085                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1086                                  iio->ident.addr.ctype3_hdr.addrlen)
1087                         goto send_mal_query;
1088                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1089                 case ICMP_AFI_IP:
1090                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1091                                 goto send_mal_query;
1092                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1093                         break;
1094 #if IS_ENABLED(CONFIG_IPV6)
1095                 case ICMP_AFI_IP6:
1096                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1097                                 goto send_mal_query;
1098                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1099                         dev_hold(dev);
1100                         break;
1101 #endif
1102                 default:
1103                         goto send_mal_query;
1104                 }
1105                 break;
1106         default:
1107                 goto send_mal_query;
1108         }
1109         if (!dev) {
1110                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1111                 return true;
1112         }
1113         /* Fill bits in reply message */
1114         if (dev->flags & IFF_UP)
1115                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1116         if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1117                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1118         if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1119                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1120         dev_put(dev);
1121         icmphdr->un.echo.sequence |= htons(status);
1122         return true;
1123 send_mal_query:
1124         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1125         return true;
1126 }
1127 EXPORT_SYMBOL_GPL(icmp_build_probe);
1128
1129 /*
1130  *      Handle ICMP Timestamp requests.
1131  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1132  *                SHOULD be in the kernel for minimum random latency.
1133  *                MUST be accurate to a few minutes.
1134  *                MUST be updated at least at 15Hz.
1135  */
1136 static bool icmp_timestamp(struct sk_buff *skb)
1137 {
1138         struct icmp_bxm icmp_param;
1139         /*
1140          *      Too short.
1141          */
1142         if (skb->len < 4)
1143                 goto out_err;
1144
1145         /*
1146          *      Fill in the current time as ms since midnight UT:
1147          */
1148         icmp_param.data.times[1] = inet_current_timestamp();
1149         icmp_param.data.times[2] = icmp_param.data.times[1];
1150
1151         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1152
1153         icmp_param.data.icmph      = *icmp_hdr(skb);
1154         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1155         icmp_param.data.icmph.code = 0;
1156         icmp_param.skb             = skb;
1157         icmp_param.offset          = 0;
1158         icmp_param.data_len        = 0;
1159         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1160         icmp_reply(&icmp_param, skb);
1161         return true;
1162
1163 out_err:
1164         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1165         return false;
1166 }
1167
1168 static bool icmp_discard(struct sk_buff *skb)
1169 {
1170         /* pretend it was a success */
1171         return true;
1172 }
1173
1174 /*
1175  *      Deal with incoming ICMP packets.
1176  */
1177 int icmp_rcv(struct sk_buff *skb)
1178 {
1179         struct icmphdr *icmph;
1180         struct rtable *rt = skb_rtable(skb);
1181         struct net *net = dev_net(rt->dst.dev);
1182         bool success;
1183
1184         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1185                 struct sec_path *sp = skb_sec_path(skb);
1186                 int nh;
1187
1188                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1189                                  XFRM_STATE_ICMP))
1190                         goto drop;
1191
1192                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1193                         goto drop;
1194
1195                 nh = skb_network_offset(skb);
1196                 skb_set_network_header(skb, sizeof(*icmph));
1197
1198                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1199                         goto drop;
1200
1201                 skb_set_network_header(skb, nh);
1202         }
1203
1204         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1205
1206         if (skb_checksum_simple_validate(skb))
1207                 goto csum_error;
1208
1209         if (!pskb_pull(skb, sizeof(*icmph)))
1210                 goto error;
1211
1212         icmph = icmp_hdr(skb);
1213
1214         ICMPMSGIN_INC_STATS(net, icmph->type);
1215
1216         /* Check for ICMP Extended Echo (PROBE) messages */
1217         if (icmph->type == ICMP_EXT_ECHO) {
1218                 /* We can't use icmp_pointers[].handler() because it is an array of
1219                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1220                  */
1221                 success = icmp_echo(skb);
1222                 goto success_check;
1223         }
1224
1225         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1226                 success = ping_rcv(skb);
1227                 goto success_check;
1228         }
1229
1230         /*
1231          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1232          *
1233          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1234          *                discarded.
1235          */
1236         if (icmph->type > NR_ICMP_TYPES)
1237                 goto error;
1238
1239         /*
1240          *      Parse the ICMP message
1241          */
1242
1243         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1244                 /*
1245                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1246                  *        silently ignored (we let user decide with a sysctl).
1247                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1248                  *        discarded if to broadcast/multicast.
1249                  */
1250                 if ((icmph->type == ICMP_ECHO ||
1251                      icmph->type == ICMP_TIMESTAMP) &&
1252                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1253                         goto error;
1254                 }
1255                 if (icmph->type != ICMP_ECHO &&
1256                     icmph->type != ICMP_TIMESTAMP &&
1257                     icmph->type != ICMP_ADDRESS &&
1258                     icmph->type != ICMP_ADDRESSREPLY) {
1259                         goto error;
1260                 }
1261         }
1262
1263         success = icmp_pointers[icmph->type].handler(skb);
1264 success_check:
1265         if (success)  {
1266                 consume_skb(skb);
1267                 return NET_RX_SUCCESS;
1268         }
1269
1270 drop:
1271         kfree_skb(skb);
1272         return NET_RX_DROP;
1273 csum_error:
1274         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1275 error:
1276         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1277         goto drop;
1278 }
1279
1280 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1281 {
1282         struct icmp_extobj_hdr *objh, _objh;
1283         struct icmp_ext_hdr *exth, _exth;
1284         u16 olen;
1285
1286         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1287         if (!exth)
1288                 return false;
1289         if (exth->version != 2)
1290                 return true;
1291
1292         if (exth->checksum &&
1293             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1294                 return false;
1295
1296         off += sizeof(_exth);
1297         while (off < skb->len) {
1298                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1299                 if (!objh)
1300                         return false;
1301
1302                 olen = ntohs(objh->length);
1303                 if (olen < sizeof(_objh))
1304                         return false;
1305
1306                 off += olen;
1307                 if (off > skb->len)
1308                         return false;
1309         }
1310
1311         return true;
1312 }
1313
1314 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1315                            struct sock_ee_data_rfc4884 *out,
1316                            int thlen, int off)
1317 {
1318         int hlen;
1319
1320         /* original datagram headers: end of icmph to payload (skb->data) */
1321         hlen = -skb_transport_offset(skb) - thlen;
1322
1323         /* per rfc 4884: minimal datagram length of 128 bytes */
1324         if (off < 128 || off < hlen)
1325                 return;
1326
1327         /* kernel has stripped headers: return payload offset in bytes */
1328         off -= hlen;
1329         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1330                 return;
1331
1332         out->len = off;
1333
1334         if (!ip_icmp_error_rfc4884_validate(skb, off))
1335                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1336 }
1337 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1338
1339 int icmp_err(struct sk_buff *skb, u32 info)
1340 {
1341         struct iphdr *iph = (struct iphdr *)skb->data;
1342         int offset = iph->ihl<<2;
1343         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1344         int type = icmp_hdr(skb)->type;
1345         int code = icmp_hdr(skb)->code;
1346         struct net *net = dev_net(skb->dev);
1347
1348         /*
1349          * Use ping_err to handle all icmp errors except those
1350          * triggered by ICMP_ECHOREPLY which sent from kernel.
1351          */
1352         if (icmph->type != ICMP_ECHOREPLY) {
1353                 ping_err(skb, offset, info);
1354                 return 0;
1355         }
1356
1357         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1358                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1359         else if (type == ICMP_REDIRECT)
1360                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1361
1362         return 0;
1363 }
1364
1365 /*
1366  *      This table is the definition of how we handle ICMP.
1367  */
1368 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1369         [ICMP_ECHOREPLY] = {
1370                 .handler = ping_rcv,
1371         },
1372         [1] = {
1373                 .handler = icmp_discard,
1374                 .error = 1,
1375         },
1376         [2] = {
1377                 .handler = icmp_discard,
1378                 .error = 1,
1379         },
1380         [ICMP_DEST_UNREACH] = {
1381                 .handler = icmp_unreach,
1382                 .error = 1,
1383         },
1384         [ICMP_SOURCE_QUENCH] = {
1385                 .handler = icmp_unreach,
1386                 .error = 1,
1387         },
1388         [ICMP_REDIRECT] = {
1389                 .handler = icmp_redirect,
1390                 .error = 1,
1391         },
1392         [6] = {
1393                 .handler = icmp_discard,
1394                 .error = 1,
1395         },
1396         [7] = {
1397                 .handler = icmp_discard,
1398                 .error = 1,
1399         },
1400         [ICMP_ECHO] = {
1401                 .handler = icmp_echo,
1402         },
1403         [9] = {
1404                 .handler = icmp_discard,
1405                 .error = 1,
1406         },
1407         [10] = {
1408                 .handler = icmp_discard,
1409                 .error = 1,
1410         },
1411         [ICMP_TIME_EXCEEDED] = {
1412                 .handler = icmp_unreach,
1413                 .error = 1,
1414         },
1415         [ICMP_PARAMETERPROB] = {
1416                 .handler = icmp_unreach,
1417                 .error = 1,
1418         },
1419         [ICMP_TIMESTAMP] = {
1420                 .handler = icmp_timestamp,
1421         },
1422         [ICMP_TIMESTAMPREPLY] = {
1423                 .handler = icmp_discard,
1424         },
1425         [ICMP_INFO_REQUEST] = {
1426                 .handler = icmp_discard,
1427         },
1428         [ICMP_INFO_REPLY] = {
1429                 .handler = icmp_discard,
1430         },
1431         [ICMP_ADDRESS] = {
1432                 .handler = icmp_discard,
1433         },
1434         [ICMP_ADDRESSREPLY] = {
1435                 .handler = icmp_discard,
1436         },
1437 };
1438
1439 static void __net_exit icmp_sk_exit(struct net *net)
1440 {
1441         int i;
1442
1443         for_each_possible_cpu(i)
1444                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1445         free_percpu(net->ipv4.icmp_sk);
1446         net->ipv4.icmp_sk = NULL;
1447 }
1448
1449 static int __net_init icmp_sk_init(struct net *net)
1450 {
1451         int i, err;
1452
1453         net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1454         if (!net->ipv4.icmp_sk)
1455                 return -ENOMEM;
1456
1457         for_each_possible_cpu(i) {
1458                 struct sock *sk;
1459
1460                 err = inet_ctl_sock_create(&sk, PF_INET,
1461                                            SOCK_RAW, IPPROTO_ICMP, net);
1462                 if (err < 0)
1463                         goto fail;
1464
1465                 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1466
1467                 /* Enough space for 2 64K ICMP packets, including
1468                  * sk_buff/skb_shared_info struct overhead.
1469                  */
1470                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1471
1472                 /*
1473                  * Speedup sock_wfree()
1474                  */
1475                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1476                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1477         }
1478
1479         /* Control parameters for ECHO replies. */
1480         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1481         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1482         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1483
1484         /* Control parameter - ignore bogus broadcast responses? */
1485         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1486
1487         /*
1488          *      Configurable global rate limit.
1489          *
1490          *      ratelimit defines tokens/packet consumed for dst->rate_token
1491          *      bucket ratemask defines which icmp types are ratelimited by
1492          *      setting it's bit position.
1493          *
1494          *      default:
1495          *      dest unreachable (3), source quench (4),
1496          *      time exceeded (11), parameter problem (12)
1497          */
1498
1499         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1500         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1501         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1502
1503         return 0;
1504
1505 fail:
1506         icmp_sk_exit(net);
1507         return err;
1508 }
1509
1510 static struct pernet_operations __net_initdata icmp_sk_ops = {
1511        .init = icmp_sk_init,
1512        .exit = icmp_sk_exit,
1513 };
1514
1515 int __init icmp_init(void)
1516 {
1517         return register_pernet_subsys(&icmp_sk_ops);
1518 }