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(net, 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         /* Guard against tiny mtu. We need to include at least one
 753          * IP network header for this message to make any sense.
 754          */
 755         if (room <= (int)sizeof(struct iphdr))
 756                 goto ende;
 757
 758         icmp_param.data_len = skb_in->len - icmp_param.offset;
 759         if (icmp_param.data_len > room)
 760                 icmp_param.data_len = room;
 761         icmp_param.head_len = sizeof(struct icmphdr);
 762
 763         /* if we don't have a source address at this point, fall back to the
 764          * dummy address instead of sending out a packet with a source address
 765          * of 0.0.0.0
 766          */
 767         if (!fl4.saddr)
 768                 fl4.saddr = htonl(INADDR_DUMMY);
 769
 770         icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
 771 ende:
 772         ip_rt_put(rt);
 773 out_unlock:
 774         icmp_xmit_unlock(sk);
 775 out_bh_enable:
 776         local_bh_enable();
 777 out:;
 778 }
 779 EXPORT_SYMBOL(__icmp_send);
 780
 781 #if IS_ENABLED(CONFIG_NF_NAT)
 782 #include <net/netfilter/nf_conntrack.h>
 783 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 784 {
 785         struct sk_buff *cloned_skb = NULL;
 786         struct ip_options opts = { 0 };
 787         enum ip_conntrack_info ctinfo;
 788         struct nf_conn *ct;
 789         __be32 orig_ip;
 790
 791         ct = nf_ct_get(skb_in, &ctinfo);
 792         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 793                 __icmp_send(skb_in, type, code, info, &opts);
 794                 return;
 795         }
 796
 797         if (skb_shared(skb_in))
 798                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 799
 800         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 801             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 802             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 803             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 804                 goto out;
 805
 806         orig_ip = ip_hdr(skb_in)->saddr;
 807         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 808         __icmp_send(skb_in, type, code, info, &opts);
 809         ip_hdr(skb_in)->saddr = orig_ip;
 810 out:
 811         consume_skb(cloned_skb);
 812 }
 813 EXPORT_SYMBOL(icmp_ndo_send);
 814 #endif
 815
 816 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 817 {
 818         const struct iphdr *iph = (const struct iphdr *)skb->data;
 819         const struct net_protocol *ipprot;
 820         int protocol = iph->protocol;
 821
 822         /* Checkin full IP header plus 8 bytes of protocol to
 823          * avoid additional coding at protocol handlers.
 824          */
 825         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 826                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 827                 return;
 828         }
 829
 830         raw_icmp_error(skb, protocol, info);
 831
 832         ipprot = rcu_dereference(inet_protos[protocol]);
 833         if (ipprot && ipprot->err_handler)
 834                 ipprot->err_handler(skb, info);
 835 }
 836
 837 static bool icmp_tag_validation(int proto)
 838 {
 839         bool ok;
 840
 841         rcu_read_lock();
 842         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 843         rcu_read_unlock();
 844         return ok;
 845 }
 846
 847 /*
 848  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 849  *      ICMP_PARAMETERPROB.
 850  */
 851
 852 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
 853 {
 854         enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
 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                 reason = SKB_DROP_REASON_IP_INHDR;
 876                 goto out_err;
 877         }
 878
 879         switch (icmph->type) {
 880         case ICMP_DEST_UNREACH:
 881                 switch (icmph->code & 15) {
 882                 case ICMP_NET_UNREACH:
 883                 case ICMP_HOST_UNREACH:
 884                 case ICMP_PROT_UNREACH:
 885                 case ICMP_PORT_UNREACH:
 886                         break;
 887                 case ICMP_FRAG_NEEDED:
 888                         /* for documentation of the ip_no_pmtu_disc
 889                          * values please see
 890                          * Documentation/networking/ip-sysctl.rst
 891                          */
 892                         switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
 893                         default:
 894                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 895                                                     &iph->daddr);
 896                                 break;
 897                         case 2:
 898                                 goto out;
 899                         case 3:
 900                                 if (!icmp_tag_validation(iph->protocol))
 901                                         goto out;
 902                                 fallthrough;
 903                         case 0:
 904                                 info = ntohs(icmph->un.frag.mtu);
 905                         }
 906                         break;
 907                 case ICMP_SR_FAILED:
 908                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 909                                             &iph->daddr);
 910                         break;
 911                 default:
 912                         break;
 913                 }
 914                 if (icmph->code > NR_ICMP_UNREACH)
 915                         goto out;
 916                 break;
 917         case ICMP_PARAMETERPROB:
 918                 info = ntohl(icmph->un.gateway) >> 24;
 919                 break;
 920         case ICMP_TIME_EXCEEDED:
 921                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 922                 if (icmph->code == ICMP_EXC_FRAGTIME)
 923                         goto out;
 924                 break;
 925         }
 926
 927         /*
 928          *      Throw it at our lower layers
 929          *
 930          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 931          *                header.
 932          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 933          *                transport layer.
 934          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 935          *                transport layer.
 936          */
 937
 938         /*
 939          *      Check the other end isn't violating RFC 1122. Some routers send
 940          *      bogus responses to broadcast frames. If you see this message
 941          *      first check your netmask matches at both ends, if it does then
 942          *      get the other vendor to fix their kit.
 943          */
 944
 945         if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
 946             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 947                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 948                                      &ip_hdr(skb)->saddr,
 949                                      icmph->type, icmph->code,
 950                                      &iph->daddr, skb->dev->name);
 951                 goto out;
 952         }
 953
 954         icmp_socket_deliver(skb, info);
 955
 956 out:
 957         return reason;
 958 out_err:
 959         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 960         return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
 961 }
 962
 963
 964 /*
 965  *      Handle ICMP_REDIRECT.
 966  */
 967
 968 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 969 {
 970         if (skb->len < sizeof(struct iphdr)) {
 971                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 972                 return SKB_DROP_REASON_PKT_TOO_SMALL;
 973         }
 974
 975         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 976                 /* there aught to be a stat */
 977                 return SKB_DROP_REASON_NOMEM;
 978         }
 979
 980         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 981         return SKB_NOT_DROPPED_YET;
 982 }
 983
 984 /*
 985  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 986  *
 987  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 988  *                requests.
 989  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 990  *                included in the reply.
 991  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 992  *                echo requests, MUST have default=NOT.
 993  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 994  *                Extended Echo Functionality, MUST be disabled by default
 995  *      See also WRT handling of options once they are done and working.
 996  */
 997
 998 static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
 999 {
1000         struct icmp_bxm icmp_param;
1001         struct net *net;
1002
1003         net = dev_net(skb_dst(skb)->dev);
1004         /* should there be an ICMP stat for ignored echos? */
1005         if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1006                 return SKB_NOT_DROPPED_YET;
1007
1008         icmp_param.data.icmph      = *icmp_hdr(skb);
1009         icmp_param.skb             = skb;
1010         icmp_param.offset          = 0;
1011         icmp_param.data_len        = skb->len;
1012         icmp_param.head_len        = sizeof(struct icmphdr);
1013
1014         if (icmp_param.data.icmph.type == ICMP_ECHO)
1015                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1016         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1017                 return SKB_NOT_DROPPED_YET;
1018
1019         icmp_reply(&icmp_param, skb);
1020         return SKB_NOT_DROPPED_YET;
1021 }
1022
1023 /*      Helper for icmp_echo and icmpv6_echo_reply.
1024  *      Searches for net_device that matches PROBE interface identifier
1025  *              and builds PROBE reply message in icmphdr.
1026  *
1027  *      Returns false if PROBE responses are disabled via sysctl
1028  */
1029
1030 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1031 {
1032         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1033         struct icmp_ext_echo_iio *iio, _iio;
1034         struct net *net = dev_net(skb->dev);
1035         struct net_device *dev;
1036         char buff[IFNAMSIZ];
1037         u16 ident_len;
1038         u8 status;
1039
1040         if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1041                 return false;
1042
1043         /* We currently only support probing interfaces on the proxy node
1044          * Check to ensure L-bit is set
1045          */
1046         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1047                 return false;
1048         /* Clear status bits in reply message */
1049         icmphdr->un.echo.sequence &= htons(0xFF00);
1050         if (icmphdr->type == ICMP_EXT_ECHO)
1051                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1052         else
1053                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1054         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1055         /* Size of iio is class_type dependent.
1056          * Only check header here and assign length based on ctype in the switch statement
1057          */
1058         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1059         if (!ext_hdr || !iio)
1060                 goto send_mal_query;
1061         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1062             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1063                 goto send_mal_query;
1064         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1065         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1066                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1067         if (!iio)
1068                 goto send_mal_query;
1069
1070         status = 0;
1071         dev = NULL;
1072         switch (iio->extobj_hdr.class_type) {
1073         case ICMP_EXT_ECHO_CTYPE_NAME:
1074                 if (ident_len >= IFNAMSIZ)
1075                         goto send_mal_query;
1076                 memset(buff, 0, sizeof(buff));
1077                 memcpy(buff, &iio->ident.name, ident_len);
1078                 dev = dev_get_by_name(net, buff);
1079                 break;
1080         case ICMP_EXT_ECHO_CTYPE_INDEX:
1081                 if (ident_len != sizeof(iio->ident.ifindex))
1082                         goto send_mal_query;
1083                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1084                 break;
1085         case ICMP_EXT_ECHO_CTYPE_ADDR:
1086                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1087                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1088                                  iio->ident.addr.ctype3_hdr.addrlen)
1089                         goto send_mal_query;
1090                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1091                 case ICMP_AFI_IP:
1092                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1093                                 goto send_mal_query;
1094                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1095                         break;
1096 #if IS_ENABLED(CONFIG_IPV6)
1097                 case ICMP_AFI_IP6:
1098                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1099                                 goto send_mal_query;
1100                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1101                         dev_hold(dev);
1102                         break;
1103 #endif
1104                 default:
1105                         goto send_mal_query;
1106                 }
1107                 break;
1108         default:
1109                 goto send_mal_query;
1110         }
1111         if (!dev) {
1112                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1113                 return true;
1114         }
1115         /* Fill bits in reply message */
1116         if (dev->flags & IFF_UP)
1117                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1118         if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1119                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1120         if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1121                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1122         dev_put(dev);
1123         icmphdr->un.echo.sequence |= htons(status);
1124         return true;
1125 send_mal_query:
1126         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1127         return true;
1128 }
1129 EXPORT_SYMBOL_GPL(icmp_build_probe);
1130
1131 /*
1132  *      Handle ICMP Timestamp requests.
1133  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1134  *                SHOULD be in the kernel for minimum random latency.
1135  *                MUST be accurate to a few minutes.
1136  *                MUST be updated at least at 15Hz.
1137  */
1138 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1139 {
1140         struct icmp_bxm icmp_param;
1141         /*
1142          *      Too short.
1143          */
1144         if (skb->len < 4)
1145                 goto out_err;
1146
1147         /*
1148          *      Fill in the current time as ms since midnight UT:
1149          */
1150         icmp_param.data.times[1] = inet_current_timestamp();
1151         icmp_param.data.times[2] = icmp_param.data.times[1];
1152
1153         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1154
1155         icmp_param.data.icmph      = *icmp_hdr(skb);
1156         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1157         icmp_param.data.icmph.code = 0;
1158         icmp_param.skb             = skb;
1159         icmp_param.offset          = 0;
1160         icmp_param.data_len        = 0;
1161         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1162         icmp_reply(&icmp_param, skb);
1163         return SKB_NOT_DROPPED_YET;
1164
1165 out_err:
1166         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1167         return SKB_DROP_REASON_PKT_TOO_SMALL;
1168 }
1169
1170 static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1171 {
1172         /* pretend it was a success */
1173         return SKB_NOT_DROPPED_YET;
1174 }
1175
1176 /*
1177  *      Deal with incoming ICMP packets.
1178  */
1179 int icmp_rcv(struct sk_buff *skb)
1180 {
1181         enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1182         struct rtable *rt = skb_rtable(skb);
1183         struct net *net = dev_net(rt->dst.dev);
1184         struct icmphdr *icmph;
1185
1186         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1187                 struct sec_path *sp = skb_sec_path(skb);
1188                 int nh;
1189
1190                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1191                                  XFRM_STATE_ICMP)) {
1192                         reason = SKB_DROP_REASON_XFRM_POLICY;
1193                         goto drop;
1194                 }
1195
1196                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1197                         goto drop;
1198
1199                 nh = skb_network_offset(skb);
1200                 skb_set_network_header(skb, sizeof(*icmph));
1201
1202                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1203                                                 skb)) {
1204                         reason = SKB_DROP_REASON_XFRM_POLICY;
1205                         goto drop;
1206                 }
1207
1208                 skb_set_network_header(skb, nh);
1209         }
1210
1211         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1212
1213         if (skb_checksum_simple_validate(skb))
1214                 goto csum_error;
1215
1216         if (!pskb_pull(skb, sizeof(*icmph)))
1217                 goto error;
1218
1219         icmph = icmp_hdr(skb);
1220
1221         ICMPMSGIN_INC_STATS(net, icmph->type);
1222
1223         /* Check for ICMP Extended Echo (PROBE) messages */
1224         if (icmph->type == ICMP_EXT_ECHO) {
1225                 /* We can't use icmp_pointers[].handler() because it is an array of
1226                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1227                  */
1228                 reason = icmp_echo(skb);
1229                 goto reason_check;
1230         }
1231
1232         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1233                 reason = ping_rcv(skb);
1234                 goto reason_check;
1235         }
1236
1237         /*
1238          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1239          *
1240          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1241          *                discarded.
1242          */
1243         if (icmph->type > NR_ICMP_TYPES) {
1244                 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1245                 goto error;
1246         }
1247
1248         /*
1249          *      Parse the ICMP message
1250          */
1251
1252         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1253                 /*
1254                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1255                  *        silently ignored (we let user decide with a sysctl).
1256                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1257                  *        discarded if to broadcast/multicast.
1258                  */
1259                 if ((icmph->type == ICMP_ECHO ||
1260                      icmph->type == ICMP_TIMESTAMP) &&
1261                     READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1262                         reason = SKB_DROP_REASON_INVALID_PROTO;
1263                         goto error;
1264                 }
1265                 if (icmph->type != ICMP_ECHO &&
1266                     icmph->type != ICMP_TIMESTAMP &&
1267                     icmph->type != ICMP_ADDRESS &&
1268                     icmph->type != ICMP_ADDRESSREPLY) {
1269                         reason = SKB_DROP_REASON_INVALID_PROTO;
1270                         goto error;
1271                 }
1272         }
1273
1274         reason = icmp_pointers[icmph->type].handler(skb);
1275 reason_check:
1276         if (!reason)  {
1277                 consume_skb(skb);
1278                 return NET_RX_SUCCESS;
1279         }
1280
1281 drop:
1282         kfree_skb_reason(skb, reason);
1283         return NET_RX_DROP;
1284 csum_error:
1285         reason = SKB_DROP_REASON_ICMP_CSUM;
1286         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1287 error:
1288         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1289         goto drop;
1290 }
1291
1292 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1293 {
1294         struct icmp_extobj_hdr *objh, _objh;
1295         struct icmp_ext_hdr *exth, _exth;
1296         u16 olen;
1297
1298         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1299         if (!exth)
1300                 return false;
1301         if (exth->version != 2)
1302                 return true;
1303
1304         if (exth->checksum &&
1305             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1306                 return false;
1307
1308         off += sizeof(_exth);
1309         while (off < skb->len) {
1310                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1311                 if (!objh)
1312                         return false;
1313
1314                 olen = ntohs(objh->length);
1315                 if (olen < sizeof(_objh))
1316                         return false;
1317
1318                 off += olen;
1319                 if (off > skb->len)
1320                         return false;
1321         }
1322
1323         return true;
1324 }
1325
1326 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1327                            struct sock_ee_data_rfc4884 *out,
1328                            int thlen, int off)
1329 {
1330         int hlen;
1331
1332         /* original datagram headers: end of icmph to payload (skb->data) */
1333         hlen = -skb_transport_offset(skb) - thlen;
1334
1335         /* per rfc 4884: minimal datagram length of 128 bytes */
1336         if (off < 128 || off < hlen)
1337                 return;
1338
1339         /* kernel has stripped headers: return payload offset in bytes */
1340         off -= hlen;
1341         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1342                 return;
1343
1344         out->len = off;
1345
1346         if (!ip_icmp_error_rfc4884_validate(skb, off))
1347                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1348 }
1349 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1350
1351 int icmp_err(struct sk_buff *skb, u32 info)
1352 {
1353         struct iphdr *iph = (struct iphdr *)skb->data;
1354         int offset = iph->ihl<<2;
1355         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1356         int type = icmp_hdr(skb)->type;
1357         int code = icmp_hdr(skb)->code;
1358         struct net *net = dev_net(skb->dev);
1359
1360         /*
1361          * Use ping_err to handle all icmp errors except those
1362          * triggered by ICMP_ECHOREPLY which sent from kernel.
1363          */
1364         if (icmph->type != ICMP_ECHOREPLY) {
1365                 ping_err(skb, offset, info);
1366                 return 0;
1367         }
1368
1369         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1370                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1371         else if (type == ICMP_REDIRECT)
1372                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1373
1374         return 0;
1375 }
1376
1377 /*
1378  *      This table is the definition of how we handle ICMP.
1379  */
1380 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1381         [ICMP_ECHOREPLY] = {
1382                 .handler = ping_rcv,
1383         },
1384         [1] = {
1385                 .handler = icmp_discard,
1386                 .error = 1,
1387         },
1388         [2] = {
1389                 .handler = icmp_discard,
1390                 .error = 1,
1391         },
1392         [ICMP_DEST_UNREACH] = {
1393                 .handler = icmp_unreach,
1394                 .error = 1,
1395         },
1396         [ICMP_SOURCE_QUENCH] = {
1397                 .handler = icmp_unreach,
1398                 .error = 1,
1399         },
1400         [ICMP_REDIRECT] = {
1401                 .handler = icmp_redirect,
1402                 .error = 1,
1403         },
1404         [6] = {
1405                 .handler = icmp_discard,
1406                 .error = 1,
1407         },
1408         [7] = {
1409                 .handler = icmp_discard,
1410                 .error = 1,
1411         },
1412         [ICMP_ECHO] = {
1413                 .handler = icmp_echo,
1414         },
1415         [9] = {
1416                 .handler = icmp_discard,
1417                 .error = 1,
1418         },
1419         [10] = {
1420                 .handler = icmp_discard,
1421                 .error = 1,
1422         },
1423         [ICMP_TIME_EXCEEDED] = {
1424                 .handler = icmp_unreach,
1425                 .error = 1,
1426         },
1427         [ICMP_PARAMETERPROB] = {
1428                 .handler = icmp_unreach,
1429                 .error = 1,
1430         },
1431         [ICMP_TIMESTAMP] = {
1432                 .handler = icmp_timestamp,
1433         },
1434         [ICMP_TIMESTAMPREPLY] = {
1435                 .handler = icmp_discard,
1436         },
1437         [ICMP_INFO_REQUEST] = {
1438                 .handler = icmp_discard,
1439         },
1440         [ICMP_INFO_REPLY] = {
1441                 .handler = icmp_discard,
1442         },
1443         [ICMP_ADDRESS] = {
1444                 .handler = icmp_discard,
1445         },
1446         [ICMP_ADDRESSREPLY] = {
1447                 .handler = icmp_discard,
1448         },
1449 };
1450
1451 static int __net_init icmp_sk_init(struct net *net)
1452 {
1453         /* Control parameters for ECHO replies. */
1454         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1455         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1456         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1457
1458         /* Control parameter - ignore bogus broadcast responses? */
1459         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1460
1461         /*
1462          *      Configurable global rate limit.
1463          *
1464          *      ratelimit defines tokens/packet consumed for dst->rate_token
1465          *      bucket ratemask defines which icmp types are ratelimited by
1466          *      setting it's bit position.
1467          *
1468          *      default:
1469          *      dest unreachable (3), source quench (4),
1470          *      time exceeded (11), parameter problem (12)
1471          */
1472
1473         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1474         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1475         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1476
1477         return 0;
1478 }
1479
1480 static struct pernet_operations __net_initdata icmp_sk_ops = {
1481        .init = icmp_sk_init,
1482 };
1483
1484 int __init icmp_init(void)
1485 {
1486         int err, i;
1487
1488         for_each_possible_cpu(i) {
1489                 struct sock *sk;
1490
1491                 err = inet_ctl_sock_create(&sk, PF_INET,
1492                                            SOCK_RAW, IPPROTO_ICMP, &init_net);
1493                 if (err < 0)
1494                         return err;
1495
1496                 per_cpu(ipv4_icmp_sk, i) = sk;
1497
1498                 /* Enough space for 2 64K ICMP packets, including
1499                  * sk_buff/skb_shared_info struct overhead.
1500                  */
1501                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1502
1503                 /*
1504                  * Speedup sock_wfree()
1505                  */
1506                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1507                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1508         }
1509         return register_pernet_subsys(&icmp_sk_ops);
1510 }