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         enum skb_drop_reason (*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 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk);
 196
 197 /* Called with BH disabled */
 198 static inline struct sock *icmp_xmit_lock(struct net *net)
 199 {
 200         struct sock *sk;
 201
 202         sk = this_cpu_read(ipv4_icmp_sk);
 203
 204         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 205                 /* This can happen if the output path signals a
 206                  * dst_link_failure() for an outgoing ICMP packet.
 207                  */
 208                 return NULL;
 209         }
 210         sock_net_set(sk, net);
 211         return sk;
 212 }
 213
 214 static inline void icmp_xmit_unlock(struct sock *sk)
 215 {
 216         sock_net_set(sk, &init_net);
 217         spin_unlock(&sk->sk_lock.slock);
 218 }
 219
 220 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
 221 int sysctl_icmp_msgs_burst __read_mostly = 50;
 222
 223 static struct {
 224         spinlock_t      lock;
 225         u32             credit;
 226         u32             stamp;
 227 } icmp_global = {
 228         .lock           = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
 229 };
 230
 231 /**
 232  * icmp_global_allow - Are we allowed to send one more ICMP message ?
 233  *
 234  * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
 235  * Returns false if we reached the limit and can not send another packet.
 236  * Note: called with BH disabled
 237  */
 238 bool icmp_global_allow(void)
 239 {
 240         u32 credit, delta, incr = 0, now = (u32)jiffies;
 241         bool rc = false;
 242
 243         /* Check if token bucket is empty and cannot be refilled
 244          * without taking the spinlock. The READ_ONCE() are paired
 245          * with the following WRITE_ONCE() in this same function.
 246          */
 247         if (!READ_ONCE(icmp_global.credit)) {
 248                 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
 249                 if (delta < HZ / 50)
 250                         return false;
 251         }
 252
 253         spin_lock(&icmp_global.lock);
 254         delta = min_t(u32, now - icmp_global.stamp, HZ);
 255         if (delta >= HZ / 50) {
 256                 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
 257                 if (incr)
 258                         WRITE_ONCE(icmp_global.stamp, now);
 259         }
 260         credit = min_t(u32, icmp_global.credit + incr,
 261                        READ_ONCE(sysctl_icmp_msgs_burst));
 262         if (credit) {
 263                 /* We want to use a credit of one in average, but need to randomize
 264                  * it for security reasons.
 265                  */
 266                 credit = max_t(int, credit - get_random_u32_below(3), 0);
 267                 rc = true;
 268         }
 269         WRITE_ONCE(icmp_global.credit, credit);
 270         spin_unlock(&icmp_global.lock);
 271         return rc;
 272 }
 273 EXPORT_SYMBOL(icmp_global_allow);
 274
 275 static bool icmpv4_mask_allow(struct net *net, int type, int code)
 276 {
 277         if (type > NR_ICMP_TYPES)
 278                 return true;
 279
 280         /* Don't limit PMTU discovery. */
 281         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 282                 return true;
 283
 284         /* Limit if icmp type is enabled in ratemask. */
 285         if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
 286                 return true;
 287
 288         return false;
 289 }
 290
 291 static bool icmpv4_global_allow(struct net *net, int type, int code)
 292 {
 293         if (icmpv4_mask_allow(net, type, code))
 294                 return true;
 295
 296         if (icmp_global_allow())
 297                 return true;
 298
 299         __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
 300         return false;
 301 }
 302
 303 /*
 304  *      Send an ICMP frame.
 305  */
 306
 307 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 308                                struct flowi4 *fl4, int type, int code)
 309 {
 310         struct dst_entry *dst = &rt->dst;
 311         struct inet_peer *peer;
 312         bool rc = true;
 313         int vif;
 314
 315         if (icmpv4_mask_allow(net, type, code))
 316                 goto out;
 317
 318         /* No rate limit on loopback */
 319         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 320                 goto out;
 321
 322         vif = l3mdev_master_ifindex(dst->dev);
 323         peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
 324         rc = inet_peer_xrlim_allow(peer,
 325                                    READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
 326         if (peer)
 327                 inet_putpeer(peer);
 328 out:
 329         if (!rc)
 330                 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST);
 331         return rc;
 332 }
 333
 334 /*
 335  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 336  */
 337 void icmp_out_count(struct net *net, unsigned char type)
 338 {
 339         ICMPMSGOUT_INC_STATS(net, type);
 340         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 341 }
 342
 343 /*
 344  *      Checksum each fragment, and on the first include the headers and final
 345  *      checksum.
 346  */
 347 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 348                           struct sk_buff *skb)
 349 {
 350         struct icmp_bxm *icmp_param = from;
 351         __wsum csum;
 352
 353         csum = skb_copy_and_csum_bits(icmp_param->skb,
 354                                       icmp_param->offset + offset,
 355                                       to, len);
 356
 357         skb->csum = csum_block_add(skb->csum, csum, odd);
 358         if (icmp_pointers[icmp_param->data.icmph.type].error)
 359                 nf_ct_attach(skb, icmp_param->skb);
 360         return 0;
 361 }
 362
 363 static void icmp_push_reply(struct sock *sk,
 364                             struct icmp_bxm *icmp_param,
 365                             struct flowi4 *fl4,
 366                             struct ipcm_cookie *ipc, struct rtable **rt)
 367 {
 368         struct sk_buff *skb;
 369
 370         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 371                            icmp_param->data_len+icmp_param->head_len,
 372                            icmp_param->head_len,
 373                            ipc, rt, MSG_DONTWAIT) < 0) {
 374                 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
 375                 ip_flush_pending_frames(sk);
 376         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 377                 struct icmphdr *icmph = icmp_hdr(skb);
 378                 __wsum csum;
 379                 struct sk_buff *skb1;
 380
 381                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 382                                                  (char *)icmph,
 383                                                  icmp_param->head_len);
 384                 skb_queue_walk(&sk->sk_write_queue, skb1) {
 385                         csum = csum_add(csum, skb1->csum);
 386                 }
 387                 icmph->checksum = csum_fold(csum);
 388                 skb->ip_summed = CHECKSUM_NONE;
 389                 ip_push_pending_frames(sk, fl4);
 390         }
 391 }
 392
 393 /*
 394  *      Driving logic for building and sending ICMP messages.
 395  */
 396
 397 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 398 {
 399         struct ipcm_cookie ipc;
 400         struct rtable *rt = skb_rtable(skb);
 401         struct net *net = dev_net(rt->dst.dev);
 402         struct flowi4 fl4;
 403         struct sock *sk;
 404         struct inet_sock *inet;
 405         __be32 daddr, saddr;
 406         u32 mark = IP4_REPLY_MARK(net, skb->mark);
 407         int type = icmp_param->data.icmph.type;
 408         int code = icmp_param->data.icmph.code;
 409
 410         if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
 411                 return;
 412
 413         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 414         local_bh_disable();
 415
 416         /* global icmp_msgs_per_sec */
 417         if (!icmpv4_global_allow(net, type, code))
 418                 goto out_bh_enable;
 419
 420         sk = icmp_xmit_lock(net);
 421         if (!sk)
 422                 goto out_bh_enable;
 423         inet = inet_sk(sk);
 424
 425         icmp_param->data.icmph.checksum = 0;
 426
 427         ipcm_init(&ipc);
 428         inet->tos = ip_hdr(skb)->tos;
 429         ipc.sockc.mark = mark;
 430         daddr = ipc.addr = ip_hdr(skb)->saddr;
 431         saddr = fib_compute_spec_dst(skb);
 432
 433         if (icmp_param->replyopts.opt.opt.optlen) {
 434                 ipc.opt = &icmp_param->replyopts.opt;
 435                 if (ipc.opt->opt.srr)
 436                         daddr = icmp_param->replyopts.opt.opt.faddr;
 437         }
 438         memset(&fl4, 0, sizeof(fl4));
 439         fl4.daddr = daddr;
 440         fl4.saddr = saddr;
 441         fl4.flowi4_mark = mark;
 442         fl4.flowi4_uid = sock_net_uid(net, NULL);
 443         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 444         fl4.flowi4_proto = IPPROTO_ICMP;
 445         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 446         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 447         rt = ip_route_output_key(net, &fl4);
 448         if (IS_ERR(rt))
 449                 goto out_unlock;
 450         if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 451                 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
 452         ip_rt_put(rt);
 453 out_unlock:
 454         icmp_xmit_unlock(sk);
 455 out_bh_enable:
 456         local_bh_enable();
 457 }
 458
 459 /*
 460  * The device used for looking up which routing table to use for sending an ICMP
 461  * error is preferably the source whenever it is set, which should ensure the
 462  * icmp error can be sent to the source host, else lookup using the routing
 463  * table of the destination device, else use the main routing table (index 0).
 464  */
 465 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
 466 {
 467         struct net_device *route_lookup_dev = NULL;
 468
 469         if (skb->dev)
 470                 route_lookup_dev = skb->dev;
 471         else if (skb_dst(skb))
 472                 route_lookup_dev = skb_dst(skb)->dev;
 473         return route_lookup_dev;
 474 }
 475
 476 static struct rtable *icmp_route_lookup(struct net *net,
 477                                         struct flowi4 *fl4,
 478                                         struct sk_buff *skb_in,
 479                                         const struct iphdr *iph,
 480                                         __be32 saddr, u8 tos, u32 mark,
 481                                         int type, int code,
 482                                         struct icmp_bxm *param)
 483 {
 484         struct net_device *route_lookup_dev;
 485         struct rtable *rt, *rt2;
 486         struct flowi4 fl4_dec;
 487         int err;
 488
 489         memset(fl4, 0, sizeof(*fl4));
 490         fl4->daddr = (param->replyopts.opt.opt.srr ?
 491                       param->replyopts.opt.opt.faddr : iph->saddr);
 492         fl4->saddr = saddr;
 493         fl4->flowi4_mark = mark;
 494         fl4->flowi4_uid = sock_net_uid(net, NULL);
 495         fl4->flowi4_tos = RT_TOS(tos);
 496         fl4->flowi4_proto = IPPROTO_ICMP;
 497         fl4->fl4_icmp_type = type;
 498         fl4->fl4_icmp_code = code;
 499         route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
 500         fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
 501
 502         security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
 503         rt = ip_route_output_key_hash(net, fl4, skb_in);
 504         if (IS_ERR(rt))
 505                 return rt;
 506
 507         /* No need to clone since we're just using its address. */
 508         rt2 = rt;
 509
 510         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 511                                            flowi4_to_flowi(fl4), NULL, 0);
 512         if (!IS_ERR(rt)) {
 513                 if (rt != rt2)
 514                         return rt;
 515         } else if (PTR_ERR(rt) == -EPERM) {
 516                 rt = NULL;
 517         } else
 518                 return rt;
 519
 520         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 521         if (err)
 522                 goto relookup_failed;
 523
 524         if (inet_addr_type_dev_table(net, route_lookup_dev,
 525                                      fl4_dec.saddr) == RTN_LOCAL) {
 526                 rt2 = __ip_route_output_key(net, &fl4_dec);
 527                 if (IS_ERR(rt2))
 528                         err = PTR_ERR(rt2);
 529         } else {
 530                 struct flowi4 fl4_2 = {};
 531                 unsigned long orefdst;
 532
 533                 fl4_2.daddr = fl4_dec.saddr;
 534                 rt2 = ip_route_output_key(net, &fl4_2);
 535                 if (IS_ERR(rt2)) {
 536                         err = PTR_ERR(rt2);
 537                         goto relookup_failed;
 538                 }
 539                 /* Ugh! */
 540                 orefdst = skb_in->_skb_refdst; /* save old refdst */
 541                 skb_dst_set(skb_in, NULL);
 542                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 543                                      RT_TOS(tos), rt2->dst.dev);
 544
 545                 dst_release(&rt2->dst);
 546                 rt2 = skb_rtable(skb_in);
 547                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
 548         }
 549
 550         if (err)
 551                 goto relookup_failed;
 552
 553         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 554                                             flowi4_to_flowi(&fl4_dec), NULL,
 555                                             XFRM_LOOKUP_ICMP);
 556         if (!IS_ERR(rt2)) {
 557                 dst_release(&rt->dst);
 558                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
 559                 rt = rt2;
 560         } else if (PTR_ERR(rt2) == -EPERM) {
 561                 if (rt)
 562                         dst_release(&rt->dst);
 563                 return rt2;
 564         } else {
 565                 err = PTR_ERR(rt2);
 566                 goto relookup_failed;
 567         }
 568         return rt;
 569
 570 relookup_failed:
 571         if (rt)
 572                 return rt;
 573         return ERR_PTR(err);
 574 }
 575
 576 /*
 577  *      Send an ICMP message in response to a situation
 578  *
 579  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 580  *                MAY send more (we do).
 581  *                      MUST NOT change this header information.
 582  *                      MUST NOT reply to a multicast/broadcast IP address.
 583  *                      MUST NOT reply to a multicast/broadcast MAC address.
 584  *                      MUST reply to only the first fragment.
 585  */
 586
 587 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 588                  const struct ip_options *opt)
 589 {
 590         struct iphdr *iph;
 591         int room;
 592         struct icmp_bxm icmp_param;
 593         struct rtable *rt = skb_rtable(skb_in);
 594         struct ipcm_cookie ipc;
 595         struct flowi4 fl4;
 596         __be32 saddr;
 597         u8  tos;
 598         u32 mark;
 599         struct net *net;
 600         struct sock *sk;
 601
 602         if (!rt)
 603                 goto out;
 604
 605         if (rt->dst.dev)
 606                 net = dev_net(rt->dst.dev);
 607         else if (skb_in->dev)
 608                 net = dev_net(skb_in->dev);
 609         else
 610                 goto out;
 611
 612         /*
 613          *      Find the original header. It is expected to be valid, of course.
 614          *      Check this, icmp_send is called from the most obscure devices
 615          *      sometimes.
 616          */
 617         iph = ip_hdr(skb_in);
 618
 619         if ((u8 *)iph < skb_in->head ||
 620             (skb_network_header(skb_in) + sizeof(*iph)) >
 621             skb_tail_pointer(skb_in))
 622                 goto out;
 623
 624         /*
 625          *      No replies to physical multicast/broadcast
 626          */
 627         if (skb_in->pkt_type != PACKET_HOST)
 628                 goto out;
 629
 630         /*
 631          *      Now check at the protocol level
 632          */
 633         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 634                 goto out;
 635
 636         /*
 637          *      Only reply to fragment 0. We byte re-order the constant
 638          *      mask for efficiency.
 639          */
 640         if (iph->frag_off & htons(IP_OFFSET))
 641                 goto out;
 642
 643         /*
 644          *      If we send an ICMP error to an ICMP error a mess would result..
 645          */
 646         if (icmp_pointers[type].error) {
 647                 /*
 648                  *      We are an error, check if we are replying to an
 649                  *      ICMP error
 650                  */
 651                 if (iph->protocol == IPPROTO_ICMP) {
 652                         u8 _inner_type, *itp;
 653
 654                         itp = skb_header_pointer(skb_in,
 655                                                  skb_network_header(skb_in) +
 656                                                  (iph->ihl << 2) +
 657                                                  offsetof(struct icmphdr,
 658                                                           type) -
 659                                                  skb_in->data,
 660                                                  sizeof(_inner_type),
 661                                                  &_inner_type);
 662                         if (!itp)
 663                                 goto out;
 664
 665                         /*
 666                          *      Assume any unknown ICMP type is an error. This
 667                          *      isn't specified by the RFC, but think about it..
 668                          */
 669                         if (*itp > NR_ICMP_TYPES ||
 670                             icmp_pointers[*itp].error)
 671                                 goto out;
 672                 }
 673         }
 674
 675         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 676         local_bh_disable();
 677
 678         /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
 679          * incoming dev is loopback.  If outgoing dev change to not be
 680          * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
 681          */
 682         if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
 683               !icmpv4_global_allow(net, type, code))
 684                 goto out_bh_enable;
 685
 686         sk = icmp_xmit_lock(net);
 687         if (!sk)
 688                 goto out_bh_enable;
 689
 690         /*
 691          *      Construct source address and options.
 692          */
 693
 694         saddr = iph->daddr;
 695         if (!(rt->rt_flags & RTCF_LOCAL)) {
 696                 struct net_device *dev = NULL;
 697
 698                 rcu_read_lock();
 699                 if (rt_is_input_route(rt) &&
 700                     READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
 701                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 702
 703                 if (dev)
 704                         saddr = inet_select_addr(dev, iph->saddr,
 705                                                  RT_SCOPE_LINK);
 706                 else
 707                         saddr = 0;
 708                 rcu_read_unlock();
 709         }
 710
 711         tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
 712                                            IPTOS_PREC_INTERNETCONTROL) :
 713                                            iph->tos;
 714         mark = IP4_REPLY_MARK(net, skb_in->mark);
 715
 716         if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
 717                 goto out_unlock;
 718
 719
 720         /*
 721          *      Prepare data for ICMP header.
 722          */
 723
 724         icmp_param.data.icmph.type       = type;
 725         icmp_param.data.icmph.code       = code;
 726         icmp_param.data.icmph.un.gateway = info;
 727         icmp_param.data.icmph.checksum   = 0;
 728         icmp_param.skb    = skb_in;
 729         icmp_param.offset = skb_network_offset(skb_in);
 730         inet_sk(sk)->tos = tos;
 731         ipcm_init(&ipc);
 732         ipc.addr = iph->saddr;
 733         ipc.opt = &icmp_param.replyopts.opt;
 734         ipc.sockc.mark = mark;
 735
 736         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 737                                type, code, &icmp_param);
 738         if (IS_ERR(rt))
 739                 goto out_unlock;
 740
 741         /* peer icmp_ratelimit */
 742         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 743                 goto ende;
 744
 745         /* RFC says return as much as we can without exceeding 576 bytes. */
 746
 747         room = dst_mtu(&rt->dst);
 748         if (room > 576)
 749                 room = 576;
 750         room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 751         room -= sizeof(struct icmphdr);
 752
 753         icmp_param.data_len = skb_in->len - icmp_param.offset;
 754         if (icmp_param.data_len > room)
 755                 icmp_param.data_len = room;
 756         icmp_param.head_len = sizeof(struct icmphdr);
 757
 758         /* if we don't have a source address at this point, fall back to the
 759          * dummy address instead of sending out a packet with a source address
 760          * of 0.0.0.0
 761          */
 762         if (!fl4.saddr)
 763                 fl4.saddr = htonl(INADDR_DUMMY);
 764
 765         icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
 766 ende:
 767         ip_rt_put(rt);
 768 out_unlock:
 769         icmp_xmit_unlock(sk);
 770 out_bh_enable:
 771         local_bh_enable();
 772 out:;
 773 }
 774 EXPORT_SYMBOL(__icmp_send);
 775
 776 #if IS_ENABLED(CONFIG_NF_NAT)
 777 #include <net/netfilter/nf_conntrack.h>
 778 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 779 {
 780         struct sk_buff *cloned_skb = NULL;
 781         struct ip_options opts = { 0 };
 782         enum ip_conntrack_info ctinfo;
 783         struct nf_conn *ct;
 784         __be32 orig_ip;
 785
 786         ct = nf_ct_get(skb_in, &ctinfo);
 787         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 788                 __icmp_send(skb_in, type, code, info, &opts);
 789                 return;
 790         }
 791
 792         if (skb_shared(skb_in))
 793                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 794
 795         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 796             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 797             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 798             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 799                 goto out;
 800
 801         orig_ip = ip_hdr(skb_in)->saddr;
 802         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 803         __icmp_send(skb_in, type, code, info, &opts);
 804         ip_hdr(skb_in)->saddr = orig_ip;
 805 out:
 806         consume_skb(cloned_skb);
 807 }
 808 EXPORT_SYMBOL(icmp_ndo_send);
 809 #endif
 810
 811 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 812 {
 813         const struct iphdr *iph = (const struct iphdr *)skb->data;
 814         const struct net_protocol *ipprot;
 815         int protocol = iph->protocol;
 816
 817         /* Checkin full IP header plus 8 bytes of protocol to
 818          * avoid additional coding at protocol handlers.
 819          */
 820         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 821                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 822                 return;
 823         }
 824
 825         raw_icmp_error(skb, protocol, info);
 826
 827         ipprot = rcu_dereference(inet_protos[protocol]);
 828         if (ipprot && ipprot->err_handler)
 829                 ipprot->err_handler(skb, info);
 830 }
 831
 832 static bool icmp_tag_validation(int proto)
 833 {
 834         bool ok;
 835
 836         rcu_read_lock();
 837         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 838         rcu_read_unlock();
 839         return ok;
 840 }
 841
 842 /*
 843  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 844  *      ICMP_PARAMETERPROB.
 845  */
 846
 847 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
 848 {
 849         enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
 850         const struct iphdr *iph;
 851         struct icmphdr *icmph;
 852         struct net *net;
 853         u32 info = 0;
 854
 855         net = dev_net(skb_dst(skb)->dev);
 856
 857         /*
 858          *      Incomplete header ?
 859          *      Only checks for the IP header, there should be an
 860          *      additional check for longer headers in upper levels.
 861          */
 862
 863         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 864                 goto out_err;
 865
 866         icmph = icmp_hdr(skb);
 867         iph   = (const struct iphdr *)skb->data;
 868
 869         if (iph->ihl < 5)  { /* Mangled header, drop. */
 870                 reason = SKB_DROP_REASON_IP_INHDR;
 871                 goto out_err;
 872         }
 873
 874         switch (icmph->type) {
 875         case ICMP_DEST_UNREACH:
 876                 switch (icmph->code & 15) {
 877                 case ICMP_NET_UNREACH:
 878                 case ICMP_HOST_UNREACH:
 879                 case ICMP_PROT_UNREACH:
 880                 case ICMP_PORT_UNREACH:
 881                         break;
 882                 case ICMP_FRAG_NEEDED:
 883                         /* for documentation of the ip_no_pmtu_disc
 884                          * values please see
 885                          * Documentation/networking/ip-sysctl.rst
 886                          */
 887                         switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
 888                         default:
 889                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 890                                                     &iph->daddr);
 891                                 break;
 892                         case 2:
 893                                 goto out;
 894                         case 3:
 895                                 if (!icmp_tag_validation(iph->protocol))
 896                                         goto out;
 897                                 fallthrough;
 898                         case 0:
 899                                 info = ntohs(icmph->un.frag.mtu);
 900                         }
 901                         break;
 902                 case ICMP_SR_FAILED:
 903                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 904                                             &iph->daddr);
 905                         break;
 906                 default:
 907                         break;
 908                 }
 909                 if (icmph->code > NR_ICMP_UNREACH)
 910                         goto out;
 911                 break;
 912         case ICMP_PARAMETERPROB:
 913                 info = ntohl(icmph->un.gateway) >> 24;
 914                 break;
 915         case ICMP_TIME_EXCEEDED:
 916                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 917                 if (icmph->code == ICMP_EXC_FRAGTIME)
 918                         goto out;
 919                 break;
 920         }
 921
 922         /*
 923          *      Throw it at our lower layers
 924          *
 925          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 926          *                header.
 927          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 928          *                transport layer.
 929          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 930          *                transport layer.
 931          */
 932
 933         /*
 934          *      Check the other end isn't violating RFC 1122. Some routers send
 935          *      bogus responses to broadcast frames. If you see this message
 936          *      first check your netmask matches at both ends, if it does then
 937          *      get the other vendor to fix their kit.
 938          */
 939
 940         if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
 941             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 942                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 943                                      &ip_hdr(skb)->saddr,
 944                                      icmph->type, icmph->code,
 945                                      &iph->daddr, skb->dev->name);
 946                 goto out;
 947         }
 948
 949         icmp_socket_deliver(skb, info);
 950
 951 out:
 952         return reason;
 953 out_err:
 954         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 955         return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
 956 }
 957
 958
 959 /*
 960  *      Handle ICMP_REDIRECT.
 961  */
 962
 963 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 964 {
 965         if (skb->len < sizeof(struct iphdr)) {
 966                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 967                 return SKB_DROP_REASON_PKT_TOO_SMALL;
 968         }
 969
 970         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 971                 /* there aught to be a stat */
 972                 return SKB_DROP_REASON_NOMEM;
 973         }
 974
 975         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 976         return SKB_NOT_DROPPED_YET;
 977 }
 978
 979 /*
 980  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 981  *
 982  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 983  *                requests.
 984  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 985  *                included in the reply.
 986  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 987  *                echo requests, MUST have default=NOT.
 988  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 989  *                Extended Echo Functionality, MUST be disabled by default
 990  *      See also WRT handling of options once they are done and working.
 991  */
 992
 993 static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
 994 {
 995         struct icmp_bxm icmp_param;
 996         struct net *net;
 997
 998         net = dev_net(skb_dst(skb)->dev);
 999         /* should there be an ICMP stat for ignored echos? */
1000         if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1001                 return SKB_NOT_DROPPED_YET;
1002
1003         icmp_param.data.icmph      = *icmp_hdr(skb);
1004         icmp_param.skb             = skb;
1005         icmp_param.offset          = 0;
1006         icmp_param.data_len        = skb->len;
1007         icmp_param.head_len        = sizeof(struct icmphdr);
1008
1009         if (icmp_param.data.icmph.type == ICMP_ECHO)
1010                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1011         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1012                 return SKB_NOT_DROPPED_YET;
1013
1014         icmp_reply(&icmp_param, skb);
1015         return SKB_NOT_DROPPED_YET;
1016 }
1017
1018 /*      Helper for icmp_echo and icmpv6_echo_reply.
1019  *      Searches for net_device that matches PROBE interface identifier
1020  *              and builds PROBE reply message in icmphdr.
1021  *
1022  *      Returns false if PROBE responses are disabled via sysctl
1023  */
1024
1025 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1026 {
1027         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1028         struct icmp_ext_echo_iio *iio, _iio;
1029         struct net *net = dev_net(skb->dev);
1030         struct net_device *dev;
1031         char buff[IFNAMSIZ];
1032         u16 ident_len;
1033         u8 status;
1034
1035         if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1036                 return false;
1037
1038         /* We currently only support probing interfaces on the proxy node
1039          * Check to ensure L-bit is set
1040          */
1041         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1042                 return false;
1043         /* Clear status bits in reply message */
1044         icmphdr->un.echo.sequence &= htons(0xFF00);
1045         if (icmphdr->type == ICMP_EXT_ECHO)
1046                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1047         else
1048                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1049         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1050         /* Size of iio is class_type dependent.
1051          * Only check header here and assign length based on ctype in the switch statement
1052          */
1053         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1054         if (!ext_hdr || !iio)
1055                 goto send_mal_query;
1056         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1057             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1058                 goto send_mal_query;
1059         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1060         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1061                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1062         if (!iio)
1063                 goto send_mal_query;
1064
1065         status = 0;
1066         dev = NULL;
1067         switch (iio->extobj_hdr.class_type) {
1068         case ICMP_EXT_ECHO_CTYPE_NAME:
1069                 if (ident_len >= IFNAMSIZ)
1070                         goto send_mal_query;
1071                 memset(buff, 0, sizeof(buff));
1072                 memcpy(buff, &iio->ident.name, ident_len);
1073                 dev = dev_get_by_name(net, buff);
1074                 break;
1075         case ICMP_EXT_ECHO_CTYPE_INDEX:
1076                 if (ident_len != sizeof(iio->ident.ifindex))
1077                         goto send_mal_query;
1078                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1079                 break;
1080         case ICMP_EXT_ECHO_CTYPE_ADDR:
1081                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1082                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1083                                  iio->ident.addr.ctype3_hdr.addrlen)
1084                         goto send_mal_query;
1085                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1086                 case ICMP_AFI_IP:
1087                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1088                                 goto send_mal_query;
1089                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1090                         break;
1091 #if IS_ENABLED(CONFIG_IPV6)
1092                 case ICMP_AFI_IP6:
1093                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1094                                 goto send_mal_query;
1095                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1096                         dev_hold(dev);
1097                         break;
1098 #endif
1099                 default:
1100                         goto send_mal_query;
1101                 }
1102                 break;
1103         default:
1104                 goto send_mal_query;
1105         }
1106         if (!dev) {
1107                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1108                 return true;
1109         }
1110         /* Fill bits in reply message */
1111         if (dev->flags & IFF_UP)
1112                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1113         if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1114                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1115         if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1116                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1117         dev_put(dev);
1118         icmphdr->un.echo.sequence |= htons(status);
1119         return true;
1120 send_mal_query:
1121         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1122         return true;
1123 }
1124 EXPORT_SYMBOL_GPL(icmp_build_probe);
1125
1126 /*
1127  *      Handle ICMP Timestamp requests.
1128  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1129  *                SHOULD be in the kernel for minimum random latency.
1130  *                MUST be accurate to a few minutes.
1131  *                MUST be updated at least at 15Hz.
1132  */
1133 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1134 {
1135         struct icmp_bxm icmp_param;
1136         /*
1137          *      Too short.
1138          */
1139         if (skb->len < 4)
1140                 goto out_err;
1141
1142         /*
1143          *      Fill in the current time as ms since midnight UT:
1144          */
1145         icmp_param.data.times[1] = inet_current_timestamp();
1146         icmp_param.data.times[2] = icmp_param.data.times[1];
1147
1148         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1149
1150         icmp_param.data.icmph      = *icmp_hdr(skb);
1151         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1152         icmp_param.data.icmph.code = 0;
1153         icmp_param.skb             = skb;
1154         icmp_param.offset          = 0;
1155         icmp_param.data_len        = 0;
1156         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1157         icmp_reply(&icmp_param, skb);
1158         return SKB_NOT_DROPPED_YET;
1159
1160 out_err:
1161         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1162         return SKB_DROP_REASON_PKT_TOO_SMALL;
1163 }
1164
1165 static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1166 {
1167         /* pretend it was a success */
1168         return SKB_NOT_DROPPED_YET;
1169 }
1170
1171 /*
1172  *      Deal with incoming ICMP packets.
1173  */
1174 int icmp_rcv(struct sk_buff *skb)
1175 {
1176         enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1177         struct rtable *rt = skb_rtable(skb);
1178         struct net *net = dev_net(rt->dst.dev);
1179         struct icmphdr *icmph;
1180
1181         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1182                 struct sec_path *sp = skb_sec_path(skb);
1183                 int nh;
1184
1185                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1186                                  XFRM_STATE_ICMP)) {
1187                         reason = SKB_DROP_REASON_XFRM_POLICY;
1188                         goto drop;
1189                 }
1190
1191                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1192                         goto drop;
1193
1194                 nh = skb_network_offset(skb);
1195                 skb_set_network_header(skb, sizeof(*icmph));
1196
1197                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1198                                                 skb)) {
1199                         reason = SKB_DROP_REASON_XFRM_POLICY;
1200                         goto drop;
1201                 }
1202
1203                 skb_set_network_header(skb, nh);
1204         }
1205
1206         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1207
1208         if (skb_checksum_simple_validate(skb))
1209                 goto csum_error;
1210
1211         if (!pskb_pull(skb, sizeof(*icmph)))
1212                 goto error;
1213
1214         icmph = icmp_hdr(skb);
1215
1216         ICMPMSGIN_INC_STATS(net, icmph->type);
1217
1218         /* Check for ICMP Extended Echo (PROBE) messages */
1219         if (icmph->type == ICMP_EXT_ECHO) {
1220                 /* We can't use icmp_pointers[].handler() because it is an array of
1221                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1222                  */
1223                 reason = icmp_echo(skb);
1224                 goto reason_check;
1225         }
1226
1227         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1228                 reason = ping_rcv(skb);
1229                 goto reason_check;
1230         }
1231
1232         /*
1233          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1234          *
1235          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1236          *                discarded.
1237          */
1238         if (icmph->type > NR_ICMP_TYPES) {
1239                 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1240                 goto error;
1241         }
1242
1243         /*
1244          *      Parse the ICMP message
1245          */
1246
1247         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1248                 /*
1249                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1250                  *        silently ignored (we let user decide with a sysctl).
1251                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1252                  *        discarded if to broadcast/multicast.
1253                  */
1254                 if ((icmph->type == ICMP_ECHO ||
1255                      icmph->type == ICMP_TIMESTAMP) &&
1256                     READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1257                         reason = SKB_DROP_REASON_INVALID_PROTO;
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                         reason = SKB_DROP_REASON_INVALID_PROTO;
1265                         goto error;
1266                 }
1267         }
1268
1269         reason = icmp_pointers[icmph->type].handler(skb);
1270 reason_check:
1271         if (!reason)  {
1272                 consume_skb(skb);
1273                 return NET_RX_SUCCESS;
1274         }
1275
1276 drop:
1277         kfree_skb_reason(skb, reason);
1278         return NET_RX_DROP;
1279 csum_error:
1280         reason = SKB_DROP_REASON_ICMP_CSUM;
1281         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1282 error:
1283         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1284         goto drop;
1285 }
1286
1287 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1288 {
1289         struct icmp_extobj_hdr *objh, _objh;
1290         struct icmp_ext_hdr *exth, _exth;
1291         u16 olen;
1292
1293         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1294         if (!exth)
1295                 return false;
1296         if (exth->version != 2)
1297                 return true;
1298
1299         if (exth->checksum &&
1300             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1301                 return false;
1302
1303         off += sizeof(_exth);
1304         while (off < skb->len) {
1305                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1306                 if (!objh)
1307                         return false;
1308
1309                 olen = ntohs(objh->length);
1310                 if (olen < sizeof(_objh))
1311                         return false;
1312
1313                 off += olen;
1314                 if (off > skb->len)
1315                         return false;
1316         }
1317
1318         return true;
1319 }
1320
1321 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1322                            struct sock_ee_data_rfc4884 *out,
1323                            int thlen, int off)
1324 {
1325         int hlen;
1326
1327         /* original datagram headers: end of icmph to payload (skb->data) */
1328         hlen = -skb_transport_offset(skb) - thlen;
1329
1330         /* per rfc 4884: minimal datagram length of 128 bytes */
1331         if (off < 128 || off < hlen)
1332                 return;
1333
1334         /* kernel has stripped headers: return payload offset in bytes */
1335         off -= hlen;
1336         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1337                 return;
1338
1339         out->len = off;
1340
1341         if (!ip_icmp_error_rfc4884_validate(skb, off))
1342                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1343 }
1344 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1345
1346 int icmp_err(struct sk_buff *skb, u32 info)
1347 {
1348         struct iphdr *iph = (struct iphdr *)skb->data;
1349         int offset = iph->ihl<<2;
1350         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1351         int type = icmp_hdr(skb)->type;
1352         int code = icmp_hdr(skb)->code;
1353         struct net *net = dev_net(skb->dev);
1354
1355         /*
1356          * Use ping_err to handle all icmp errors except those
1357          * triggered by ICMP_ECHOREPLY which sent from kernel.
1358          */
1359         if (icmph->type != ICMP_ECHOREPLY) {
1360                 ping_err(skb, offset, info);
1361                 return 0;
1362         }
1363
1364         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1365                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1366         else if (type == ICMP_REDIRECT)
1367                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1368
1369         return 0;
1370 }
1371
1372 /*
1373  *      This table is the definition of how we handle ICMP.
1374  */
1375 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1376         [ICMP_ECHOREPLY] = {
1377                 .handler = ping_rcv,
1378         },
1379         [1] = {
1380                 .handler = icmp_discard,
1381                 .error = 1,
1382         },
1383         [2] = {
1384                 .handler = icmp_discard,
1385                 .error = 1,
1386         },
1387         [ICMP_DEST_UNREACH] = {
1388                 .handler = icmp_unreach,
1389                 .error = 1,
1390         },
1391         [ICMP_SOURCE_QUENCH] = {
1392                 .handler = icmp_unreach,
1393                 .error = 1,
1394         },
1395         [ICMP_REDIRECT] = {
1396                 .handler = icmp_redirect,
1397                 .error = 1,
1398         },
1399         [6] = {
1400                 .handler = icmp_discard,
1401                 .error = 1,
1402         },
1403         [7] = {
1404                 .handler = icmp_discard,
1405                 .error = 1,
1406         },
1407         [ICMP_ECHO] = {
1408                 .handler = icmp_echo,
1409         },
1410         [9] = {
1411                 .handler = icmp_discard,
1412                 .error = 1,
1413         },
1414         [10] = {
1415                 .handler = icmp_discard,
1416                 .error = 1,
1417         },
1418         [ICMP_TIME_EXCEEDED] = {
1419                 .handler = icmp_unreach,
1420                 .error = 1,
1421         },
1422         [ICMP_PARAMETERPROB] = {
1423                 .handler = icmp_unreach,
1424                 .error = 1,
1425         },
1426         [ICMP_TIMESTAMP] = {
1427                 .handler = icmp_timestamp,
1428         },
1429         [ICMP_TIMESTAMPREPLY] = {
1430                 .handler = icmp_discard,
1431         },
1432         [ICMP_INFO_REQUEST] = {
1433                 .handler = icmp_discard,
1434         },
1435         [ICMP_INFO_REPLY] = {
1436                 .handler = icmp_discard,
1437         },
1438         [ICMP_ADDRESS] = {
1439                 .handler = icmp_discard,
1440         },
1441         [ICMP_ADDRESSREPLY] = {
1442                 .handler = icmp_discard,
1443         },
1444 };
1445
1446 static int __net_init icmp_sk_init(struct net *net)
1447 {
1448         /* Control parameters for ECHO replies. */
1449         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1450         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1451         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1452
1453         /* Control parameter - ignore bogus broadcast responses? */
1454         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1455
1456         /*
1457          *      Configurable global rate limit.
1458          *
1459          *      ratelimit defines tokens/packet consumed for dst->rate_token
1460          *      bucket ratemask defines which icmp types are ratelimited by
1461          *      setting it's bit position.
1462          *
1463          *      default:
1464          *      dest unreachable (3), source quench (4),
1465          *      time exceeded (11), parameter problem (12)
1466          */
1467
1468         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1469         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1470         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1471
1472         return 0;
1473 }
1474
1475 static struct pernet_operations __net_initdata icmp_sk_ops = {
1476        .init = icmp_sk_init,
1477 };
1478
1479 int __init icmp_init(void)
1480 {
1481         int err, i;
1482
1483         for_each_possible_cpu(i) {
1484                 struct sock *sk;
1485
1486                 err = inet_ctl_sock_create(&sk, PF_INET,
1487                                            SOCK_RAW, IPPROTO_ICMP, &init_net);
1488                 if (err < 0)
1489                         return err;
1490
1491                 per_cpu(ipv4_icmp_sk, i) = sk;
1492
1493                 /* Enough space for 2 64K ICMP packets, including
1494                  * sk_buff/skb_shared_info struct overhead.
1495                  */
1496                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1497
1498                 /*
1499                  * Speedup sock_wfree()
1500                  */
1501                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1502                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1503         }
1504         return register_pernet_subsys(&icmp_sk_ops);
1505 }