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 = 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, sysctl_icmp_msgs_burst);
 261         if (credit) {
 262                 /* We want to use a credit of one in average, but need to randomize
 263                  * it for security reasons.
 264                  */
 265                 credit = max_t(int, credit - prandom_u32_max(3), 0);
 266                 rc = true;
 267         }
 268         WRITE_ONCE(icmp_global.credit, credit);
 269         spin_unlock(&icmp_global.lock);
 270         return rc;
 271 }
 272 EXPORT_SYMBOL(icmp_global_allow);
 273
 274 static bool icmpv4_mask_allow(struct net *net, int type, int code)
 275 {
 276         if (type > NR_ICMP_TYPES)
 277                 return true;
 278
 279         /* Don't limit PMTU discovery. */
 280         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 281                 return true;
 282
 283         /* Limit if icmp type is enabled in ratemask. */
 284         if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
 285                 return true;
 286
 287         return false;
 288 }
 289
 290 static bool icmpv4_global_allow(struct net *net, int type, int code)
 291 {
 292         if (icmpv4_mask_allow(net, type, code))
 293                 return true;
 294
 295         if (icmp_global_allow())
 296                 return true;
 297
 298         return false;
 299 }
 300
 301 /*
 302  *      Send an ICMP frame.
 303  */
 304
 305 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 306                                struct flowi4 *fl4, int type, int code)
 307 {
 308         struct dst_entry *dst = &rt->dst;
 309         struct inet_peer *peer;
 310         bool rc = true;
 311         int vif;
 312
 313         if (icmpv4_mask_allow(net, type, code))
 314                 goto out;
 315
 316         /* No rate limit on loopback */
 317         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 318                 goto out;
 319
 320         vif = l3mdev_master_ifindex(dst->dev);
 321         peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
 322         rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
 323         if (peer)
 324                 inet_putpeer(peer);
 325 out:
 326         return rc;
 327 }
 328
 329 /*
 330  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 331  */
 332 void icmp_out_count(struct net *net, unsigned char type)
 333 {
 334         ICMPMSGOUT_INC_STATS(net, type);
 335         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 336 }
 337
 338 /*
 339  *      Checksum each fragment, and on the first include the headers and final
 340  *      checksum.
 341  */
 342 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 343                           struct sk_buff *skb)
 344 {
 345         struct icmp_bxm *icmp_param = from;
 346         __wsum csum;
 347
 348         csum = skb_copy_and_csum_bits(icmp_param->skb,
 349                                       icmp_param->offset + offset,
 350                                       to, len);
 351
 352         skb->csum = csum_block_add(skb->csum, csum, odd);
 353         if (icmp_pointers[icmp_param->data.icmph.type].error)
 354                 nf_ct_attach(skb, icmp_param->skb);
 355         return 0;
 356 }
 357
 358 static void icmp_push_reply(struct sock *sk,
 359                             struct icmp_bxm *icmp_param,
 360                             struct flowi4 *fl4,
 361                             struct ipcm_cookie *ipc, struct rtable **rt)
 362 {
 363         struct sk_buff *skb;
 364
 365         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 366                            icmp_param->data_len+icmp_param->head_len,
 367                            icmp_param->head_len,
 368                            ipc, rt, MSG_DONTWAIT) < 0) {
 369                 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
 370                 ip_flush_pending_frames(sk);
 371         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 372                 struct icmphdr *icmph = icmp_hdr(skb);
 373                 __wsum csum;
 374                 struct sk_buff *skb1;
 375
 376                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 377                                                  (char *)icmph,
 378                                                  icmp_param->head_len);
 379                 skb_queue_walk(&sk->sk_write_queue, skb1) {
 380                         csum = csum_add(csum, skb1->csum);
 381                 }
 382                 icmph->checksum = csum_fold(csum);
 383                 skb->ip_summed = CHECKSUM_NONE;
 384                 ip_push_pending_frames(sk, fl4);
 385         }
 386 }
 387
 388 /*
 389  *      Driving logic for building and sending ICMP messages.
 390  */
 391
 392 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 393 {
 394         struct ipcm_cookie ipc;
 395         struct rtable *rt = skb_rtable(skb);
 396         struct net *net = dev_net(rt->dst.dev);
 397         struct flowi4 fl4;
 398         struct sock *sk;
 399         struct inet_sock *inet;
 400         __be32 daddr, saddr;
 401         u32 mark = IP4_REPLY_MARK(net, skb->mark);
 402         int type = icmp_param->data.icmph.type;
 403         int code = icmp_param->data.icmph.code;
 404
 405         if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
 406                 return;
 407
 408         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 409         local_bh_disable();
 410
 411         /* global icmp_msgs_per_sec */
 412         if (!icmpv4_global_allow(net, type, code))
 413                 goto out_bh_enable;
 414
 415         sk = icmp_xmit_lock(net);
 416         if (!sk)
 417                 goto out_bh_enable;
 418         inet = inet_sk(sk);
 419
 420         icmp_param->data.icmph.checksum = 0;
 421
 422         ipcm_init(&ipc);
 423         inet->tos = ip_hdr(skb)->tos;
 424         ipc.sockc.mark = mark;
 425         daddr = ipc.addr = ip_hdr(skb)->saddr;
 426         saddr = fib_compute_spec_dst(skb);
 427
 428         if (icmp_param->replyopts.opt.opt.optlen) {
 429                 ipc.opt = &icmp_param->replyopts.opt;
 430                 if (ipc.opt->opt.srr)
 431                         daddr = icmp_param->replyopts.opt.opt.faddr;
 432         }
 433         memset(&fl4, 0, sizeof(fl4));
 434         fl4.daddr = daddr;
 435         fl4.saddr = saddr;
 436         fl4.flowi4_mark = mark;
 437         fl4.flowi4_uid = sock_net_uid(net, NULL);
 438         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 439         fl4.flowi4_proto = IPPROTO_ICMP;
 440         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 441         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 442         rt = ip_route_output_key(net, &fl4);
 443         if (IS_ERR(rt))
 444                 goto out_unlock;
 445         if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 446                 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
 447         ip_rt_put(rt);
 448 out_unlock:
 449         icmp_xmit_unlock(sk);
 450 out_bh_enable:
 451         local_bh_enable();
 452 }
 453
 454 /*
 455  * The device used for looking up which routing table to use for sending an ICMP
 456  * error is preferably the source whenever it is set, which should ensure the
 457  * icmp error can be sent to the source host, else lookup using the routing
 458  * table of the destination device, else use the main routing table (index 0).
 459  */
 460 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
 461 {
 462         struct net_device *route_lookup_dev = NULL;
 463
 464         if (skb->dev)
 465                 route_lookup_dev = skb->dev;
 466         else if (skb_dst(skb))
 467                 route_lookup_dev = skb_dst(skb)->dev;
 468         return route_lookup_dev;
 469 }
 470
 471 static struct rtable *icmp_route_lookup(struct net *net,
 472                                         struct flowi4 *fl4,
 473                                         struct sk_buff *skb_in,
 474                                         const struct iphdr *iph,
 475                                         __be32 saddr, u8 tos, u32 mark,
 476                                         int type, int code,
 477                                         struct icmp_bxm *param)
 478 {
 479         struct net_device *route_lookup_dev;
 480         struct rtable *rt, *rt2;
 481         struct flowi4 fl4_dec;
 482         int err;
 483
 484         memset(fl4, 0, sizeof(*fl4));
 485         fl4->daddr = (param->replyopts.opt.opt.srr ?
 486                       param->replyopts.opt.opt.faddr : iph->saddr);
 487         fl4->saddr = saddr;
 488         fl4->flowi4_mark = mark;
 489         fl4->flowi4_uid = sock_net_uid(net, NULL);
 490         fl4->flowi4_tos = RT_TOS(tos);
 491         fl4->flowi4_proto = IPPROTO_ICMP;
 492         fl4->fl4_icmp_type = type;
 493         fl4->fl4_icmp_code = code;
 494         route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
 495         fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
 496
 497         security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
 498         rt = ip_route_output_key_hash(net, fl4, skb_in);
 499         if (IS_ERR(rt))
 500                 return rt;
 501
 502         /* No need to clone since we're just using its address. */
 503         rt2 = rt;
 504
 505         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 506                                            flowi4_to_flowi(fl4), NULL, 0);
 507         if (!IS_ERR(rt)) {
 508                 if (rt != rt2)
 509                         return rt;
 510         } else if (PTR_ERR(rt) == -EPERM) {
 511                 rt = NULL;
 512         } else
 513                 return rt;
 514
 515         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 516         if (err)
 517                 goto relookup_failed;
 518
 519         if (inet_addr_type_dev_table(net, route_lookup_dev,
 520                                      fl4_dec.saddr) == RTN_LOCAL) {
 521                 rt2 = __ip_route_output_key(net, &fl4_dec);
 522                 if (IS_ERR(rt2))
 523                         err = PTR_ERR(rt2);
 524         } else {
 525                 struct flowi4 fl4_2 = {};
 526                 unsigned long orefdst;
 527
 528                 fl4_2.daddr = fl4_dec.saddr;
 529                 rt2 = ip_route_output_key(net, &fl4_2);
 530                 if (IS_ERR(rt2)) {
 531                         err = PTR_ERR(rt2);
 532                         goto relookup_failed;
 533                 }
 534                 /* Ugh! */
 535                 orefdst = skb_in->_skb_refdst; /* save old refdst */
 536                 skb_dst_set(skb_in, NULL);
 537                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 538                                      RT_TOS(tos), rt2->dst.dev);
 539
 540                 dst_release(&rt2->dst);
 541                 rt2 = skb_rtable(skb_in);
 542                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
 543         }
 544
 545         if (err)
 546                 goto relookup_failed;
 547
 548         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 549                                             flowi4_to_flowi(&fl4_dec), NULL,
 550                                             XFRM_LOOKUP_ICMP);
 551         if (!IS_ERR(rt2)) {
 552                 dst_release(&rt->dst);
 553                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
 554                 rt = rt2;
 555         } else if (PTR_ERR(rt2) == -EPERM) {
 556                 if (rt)
 557                         dst_release(&rt->dst);
 558                 return rt2;
 559         } else {
 560                 err = PTR_ERR(rt2);
 561                 goto relookup_failed;
 562         }
 563         return rt;
 564
 565 relookup_failed:
 566         if (rt)
 567                 return rt;
 568         return ERR_PTR(err);
 569 }
 570
 571 /*
 572  *      Send an ICMP message in response to a situation
 573  *
 574  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 575  *                MAY send more (we do).
 576  *                      MUST NOT change this header information.
 577  *                      MUST NOT reply to a multicast/broadcast IP address.
 578  *                      MUST NOT reply to a multicast/broadcast MAC address.
 579  *                      MUST reply to only the first fragment.
 580  */
 581
 582 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 583                  const struct ip_options *opt)
 584 {
 585         struct iphdr *iph;
 586         int room;
 587         struct icmp_bxm icmp_param;
 588         struct rtable *rt = skb_rtable(skb_in);
 589         struct ipcm_cookie ipc;
 590         struct flowi4 fl4;
 591         __be32 saddr;
 592         u8  tos;
 593         u32 mark;
 594         struct net *net;
 595         struct sock *sk;
 596
 597         if (!rt)
 598                 goto out;
 599
 600         if (rt->dst.dev)
 601                 net = dev_net(rt->dst.dev);
 602         else if (skb_in->dev)
 603                 net = dev_net(skb_in->dev);
 604         else
 605                 goto out;
 606
 607         /*
 608          *      Find the original header. It is expected to be valid, of course.
 609          *      Check this, icmp_send is called from the most obscure devices
 610          *      sometimes.
 611          */
 612         iph = ip_hdr(skb_in);
 613
 614         if ((u8 *)iph < skb_in->head ||
 615             (skb_network_header(skb_in) + sizeof(*iph)) >
 616             skb_tail_pointer(skb_in))
 617                 goto out;
 618
 619         /*
 620          *      No replies to physical multicast/broadcast
 621          */
 622         if (skb_in->pkt_type != PACKET_HOST)
 623                 goto out;
 624
 625         /*
 626          *      Now check at the protocol level
 627          */
 628         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 629                 goto out;
 630
 631         /*
 632          *      Only reply to fragment 0. We byte re-order the constant
 633          *      mask for efficiency.
 634          */
 635         if (iph->frag_off & htons(IP_OFFSET))
 636                 goto out;
 637
 638         /*
 639          *      If we send an ICMP error to an ICMP error a mess would result..
 640          */
 641         if (icmp_pointers[type].error) {
 642                 /*
 643                  *      We are an error, check if we are replying to an
 644                  *      ICMP error
 645                  */
 646                 if (iph->protocol == IPPROTO_ICMP) {
 647                         u8 _inner_type, *itp;
 648
 649                         itp = skb_header_pointer(skb_in,
 650                                                  skb_network_header(skb_in) +
 651                                                  (iph->ihl << 2) +
 652                                                  offsetof(struct icmphdr,
 653                                                           type) -
 654                                                  skb_in->data,
 655                                                  sizeof(_inner_type),
 656                                                  &_inner_type);
 657                         if (!itp)
 658                                 goto out;
 659
 660                         /*
 661                          *      Assume any unknown ICMP type is an error. This
 662                          *      isn't specified by the RFC, but think about it..
 663                          */
 664                         if (*itp > NR_ICMP_TYPES ||
 665                             icmp_pointers[*itp].error)
 666                                 goto out;
 667                 }
 668         }
 669
 670         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 671         local_bh_disable();
 672
 673         /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
 674          * incoming dev is loopback.  If outgoing dev change to not be
 675          * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
 676          */
 677         if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
 678               !icmpv4_global_allow(net, type, code))
 679                 goto out_bh_enable;
 680
 681         sk = icmp_xmit_lock(net);
 682         if (!sk)
 683                 goto out_bh_enable;
 684
 685         /*
 686          *      Construct source address and options.
 687          */
 688
 689         saddr = iph->daddr;
 690         if (!(rt->rt_flags & RTCF_LOCAL)) {
 691                 struct net_device *dev = NULL;
 692
 693                 rcu_read_lock();
 694                 if (rt_is_input_route(rt) &&
 695                     net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
 696                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 697
 698                 if (dev)
 699                         saddr = inet_select_addr(dev, iph->saddr,
 700                                                  RT_SCOPE_LINK);
 701                 else
 702                         saddr = 0;
 703                 rcu_read_unlock();
 704         }
 705
 706         tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
 707                                            IPTOS_PREC_INTERNETCONTROL) :
 708                                            iph->tos;
 709         mark = IP4_REPLY_MARK(net, skb_in->mark);
 710
 711         if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
 712                 goto out_unlock;
 713
 714
 715         /*
 716          *      Prepare data for ICMP header.
 717          */
 718
 719         icmp_param.data.icmph.type       = type;
 720         icmp_param.data.icmph.code       = code;
 721         icmp_param.data.icmph.un.gateway = info;
 722         icmp_param.data.icmph.checksum   = 0;
 723         icmp_param.skb    = skb_in;
 724         icmp_param.offset = skb_network_offset(skb_in);
 725         inet_sk(sk)->tos = tos;
 726         ipcm_init(&ipc);
 727         ipc.addr = iph->saddr;
 728         ipc.opt = &icmp_param.replyopts.opt;
 729         ipc.sockc.mark = mark;
 730
 731         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 732                                type, code, &icmp_param);
 733         if (IS_ERR(rt))
 734                 goto out_unlock;
 735
 736         /* peer icmp_ratelimit */
 737         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 738                 goto ende;
 739
 740         /* RFC says return as much as we can without exceeding 576 bytes. */
 741
 742         room = dst_mtu(&rt->dst);
 743         if (room > 576)
 744                 room = 576;
 745         room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 746         room -= sizeof(struct icmphdr);
 747
 748         icmp_param.data_len = skb_in->len - icmp_param.offset;
 749         if (icmp_param.data_len > room)
 750                 icmp_param.data_len = room;
 751         icmp_param.head_len = sizeof(struct icmphdr);
 752
 753         /* if we don't have a source address at this point, fall back to the
 754          * dummy address instead of sending out a packet with a source address
 755          * of 0.0.0.0
 756          */
 757         if (!fl4.saddr)
 758                 fl4.saddr = htonl(INADDR_DUMMY);
 759
 760         icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
 761 ende:
 762         ip_rt_put(rt);
 763 out_unlock:
 764         icmp_xmit_unlock(sk);
 765 out_bh_enable:
 766         local_bh_enable();
 767 out:;
 768 }
 769 EXPORT_SYMBOL(__icmp_send);
 770
 771 #if IS_ENABLED(CONFIG_NF_NAT)
 772 #include <net/netfilter/nf_conntrack.h>
 773 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 774 {
 775         struct sk_buff *cloned_skb = NULL;
 776         struct ip_options opts = { 0 };
 777         enum ip_conntrack_info ctinfo;
 778         struct nf_conn *ct;
 779         __be32 orig_ip;
 780
 781         ct = nf_ct_get(skb_in, &ctinfo);
 782         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 783                 __icmp_send(skb_in, type, code, info, &opts);
 784                 return;
 785         }
 786
 787         if (skb_shared(skb_in))
 788                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 789
 790         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 791             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 792             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 793             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 794                 goto out;
 795
 796         orig_ip = ip_hdr(skb_in)->saddr;
 797         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 798         __icmp_send(skb_in, type, code, info, &opts);
 799         ip_hdr(skb_in)->saddr = orig_ip;
 800 out:
 801         consume_skb(cloned_skb);
 802 }
 803 EXPORT_SYMBOL(icmp_ndo_send);
 804 #endif
 805
 806 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 807 {
 808         const struct iphdr *iph = (const struct iphdr *)skb->data;
 809         const struct net_protocol *ipprot;
 810         int protocol = iph->protocol;
 811
 812         /* Checkin full IP header plus 8 bytes of protocol to
 813          * avoid additional coding at protocol handlers.
 814          */
 815         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 816                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 817                 return;
 818         }
 819
 820         raw_icmp_error(skb, protocol, info);
 821
 822         ipprot = rcu_dereference(inet_protos[protocol]);
 823         if (ipprot && ipprot->err_handler)
 824                 ipprot->err_handler(skb, info);
 825 }
 826
 827 static bool icmp_tag_validation(int proto)
 828 {
 829         bool ok;
 830
 831         rcu_read_lock();
 832         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 833         rcu_read_unlock();
 834         return ok;
 835 }
 836
 837 /*
 838  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 839  *      ICMP_PARAMETERPROB.
 840  */
 841
 842 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
 843 {
 844         enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
 845         const struct iphdr *iph;
 846         struct icmphdr *icmph;
 847         struct net *net;
 848         u32 info = 0;
 849
 850         net = dev_net(skb_dst(skb)->dev);
 851
 852         /*
 853          *      Incomplete header ?
 854          *      Only checks for the IP header, there should be an
 855          *      additional check for longer headers in upper levels.
 856          */
 857
 858         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 859                 goto out_err;
 860
 861         icmph = icmp_hdr(skb);
 862         iph   = (const struct iphdr *)skb->data;
 863
 864         if (iph->ihl < 5)  { /* Mangled header, drop. */
 865                 reason = SKB_DROP_REASON_IP_INHDR;
 866                 goto out_err;
 867         }
 868
 869         switch (icmph->type) {
 870         case ICMP_DEST_UNREACH:
 871                 switch (icmph->code & 15) {
 872                 case ICMP_NET_UNREACH:
 873                 case ICMP_HOST_UNREACH:
 874                 case ICMP_PROT_UNREACH:
 875                 case ICMP_PORT_UNREACH:
 876                         break;
 877                 case ICMP_FRAG_NEEDED:
 878                         /* for documentation of the ip_no_pmtu_disc
 879                          * values please see
 880                          * Documentation/networking/ip-sysctl.rst
 881                          */
 882                         switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
 883                         default:
 884                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 885                                                     &iph->daddr);
 886                                 break;
 887                         case 2:
 888                                 goto out;
 889                         case 3:
 890                                 if (!icmp_tag_validation(iph->protocol))
 891                                         goto out;
 892                                 fallthrough;
 893                         case 0:
 894                                 info = ntohs(icmph->un.frag.mtu);
 895                         }
 896                         break;
 897                 case ICMP_SR_FAILED:
 898                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 899                                             &iph->daddr);
 900                         break;
 901                 default:
 902                         break;
 903                 }
 904                 if (icmph->code > NR_ICMP_UNREACH)
 905                         goto out;
 906                 break;
 907         case ICMP_PARAMETERPROB:
 908                 info = ntohl(icmph->un.gateway) >> 24;
 909                 break;
 910         case ICMP_TIME_EXCEEDED:
 911                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 912                 if (icmph->code == ICMP_EXC_FRAGTIME)
 913                         goto out;
 914                 break;
 915         }
 916
 917         /*
 918          *      Throw it at our lower layers
 919          *
 920          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 921          *                header.
 922          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 923          *                transport layer.
 924          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 925          *                transport layer.
 926          */
 927
 928         /*
 929          *      Check the other end isn't violating RFC 1122. Some routers send
 930          *      bogus responses to broadcast frames. If you see this message
 931          *      first check your netmask matches at both ends, if it does then
 932          *      get the other vendor to fix their kit.
 933          */
 934
 935         if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
 936             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 937                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 938                                      &ip_hdr(skb)->saddr,
 939                                      icmph->type, icmph->code,
 940                                      &iph->daddr, skb->dev->name);
 941                 goto out;
 942         }
 943
 944         icmp_socket_deliver(skb, info);
 945
 946 out:
 947         return reason;
 948 out_err:
 949         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 950         return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
 951 }
 952
 953
 954 /*
 955  *      Handle ICMP_REDIRECT.
 956  */
 957
 958 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 959 {
 960         if (skb->len < sizeof(struct iphdr)) {
 961                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 962                 return SKB_DROP_REASON_PKT_TOO_SMALL;
 963         }
 964
 965         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 966                 /* there aught to be a stat */
 967                 return SKB_DROP_REASON_NOMEM;
 968         }
 969
 970         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 971         return SKB_NOT_DROPPED_YET;
 972 }
 973
 974 /*
 975  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 976  *
 977  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 978  *                requests.
 979  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 980  *                included in the reply.
 981  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 982  *                echo requests, MUST have default=NOT.
 983  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 984  *                Extended Echo Functionality, MUST be disabled by default
 985  *      See also WRT handling of options once they are done and working.
 986  */
 987
 988 static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
 989 {
 990         struct icmp_bxm icmp_param;
 991         struct net *net;
 992
 993         net = dev_net(skb_dst(skb)->dev);
 994         /* should there be an ICMP stat for ignored echos? */
 995         if (net->ipv4.sysctl_icmp_echo_ignore_all)
 996                 return SKB_NOT_DROPPED_YET;
 997
 998         icmp_param.data.icmph      = *icmp_hdr(skb);
 999         icmp_param.skb             = skb;
1000         icmp_param.offset          = 0;
1001         icmp_param.data_len        = skb->len;
1002         icmp_param.head_len        = sizeof(struct icmphdr);
1003
1004         if (icmp_param.data.icmph.type == ICMP_ECHO)
1005                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1006         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1007                 return SKB_NOT_DROPPED_YET;
1008
1009         icmp_reply(&icmp_param, skb);
1010         return SKB_NOT_DROPPED_YET;
1011 }
1012
1013 /*      Helper for icmp_echo and icmpv6_echo_reply.
1014  *      Searches for net_device that matches PROBE interface identifier
1015  *              and builds PROBE reply message in icmphdr.
1016  *
1017  *      Returns false if PROBE responses are disabled via sysctl
1018  */
1019
1020 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1021 {
1022         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1023         struct icmp_ext_echo_iio *iio, _iio;
1024         struct net *net = dev_net(skb->dev);
1025         struct net_device *dev;
1026         char buff[IFNAMSIZ];
1027         u16 ident_len;
1028         u8 status;
1029
1030         if (!net->ipv4.sysctl_icmp_echo_enable_probe)
1031                 return false;
1032
1033         /* We currently only support probing interfaces on the proxy node
1034          * Check to ensure L-bit is set
1035          */
1036         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1037                 return false;
1038         /* Clear status bits in reply message */
1039         icmphdr->un.echo.sequence &= htons(0xFF00);
1040         if (icmphdr->type == ICMP_EXT_ECHO)
1041                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1042         else
1043                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1044         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1045         /* Size of iio is class_type dependent.
1046          * Only check header here and assign length based on ctype in the switch statement
1047          */
1048         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1049         if (!ext_hdr || !iio)
1050                 goto send_mal_query;
1051         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1052             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1053                 goto send_mal_query;
1054         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1055         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1056                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1057         if (!iio)
1058                 goto send_mal_query;
1059
1060         status = 0;
1061         dev = NULL;
1062         switch (iio->extobj_hdr.class_type) {
1063         case ICMP_EXT_ECHO_CTYPE_NAME:
1064                 if (ident_len >= IFNAMSIZ)
1065                         goto send_mal_query;
1066                 memset(buff, 0, sizeof(buff));
1067                 memcpy(buff, &iio->ident.name, ident_len);
1068                 dev = dev_get_by_name(net, buff);
1069                 break;
1070         case ICMP_EXT_ECHO_CTYPE_INDEX:
1071                 if (ident_len != sizeof(iio->ident.ifindex))
1072                         goto send_mal_query;
1073                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1074                 break;
1075         case ICMP_EXT_ECHO_CTYPE_ADDR:
1076                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1077                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1078                                  iio->ident.addr.ctype3_hdr.addrlen)
1079                         goto send_mal_query;
1080                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1081                 case ICMP_AFI_IP:
1082                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1083                                 goto send_mal_query;
1084                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1085                         break;
1086 #if IS_ENABLED(CONFIG_IPV6)
1087                 case ICMP_AFI_IP6:
1088                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1089                                 goto send_mal_query;
1090                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1091                         dev_hold(dev);
1092                         break;
1093 #endif
1094                 default:
1095                         goto send_mal_query;
1096                 }
1097                 break;
1098         default:
1099                 goto send_mal_query;
1100         }
1101         if (!dev) {
1102                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1103                 return true;
1104         }
1105         /* Fill bits in reply message */
1106         if (dev->flags & IFF_UP)
1107                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1108         if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1109                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1110         if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1111                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1112         dev_put(dev);
1113         icmphdr->un.echo.sequence |= htons(status);
1114         return true;
1115 send_mal_query:
1116         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1117         return true;
1118 }
1119 EXPORT_SYMBOL_GPL(icmp_build_probe);
1120
1121 /*
1122  *      Handle ICMP Timestamp requests.
1123  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1124  *                SHOULD be in the kernel for minimum random latency.
1125  *                MUST be accurate to a few minutes.
1126  *                MUST be updated at least at 15Hz.
1127  */
1128 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1129 {
1130         struct icmp_bxm icmp_param;
1131         /*
1132          *      Too short.
1133          */
1134         if (skb->len < 4)
1135                 goto out_err;
1136
1137         /*
1138          *      Fill in the current time as ms since midnight UT:
1139          */
1140         icmp_param.data.times[1] = inet_current_timestamp();
1141         icmp_param.data.times[2] = icmp_param.data.times[1];
1142
1143         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1144
1145         icmp_param.data.icmph      = *icmp_hdr(skb);
1146         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1147         icmp_param.data.icmph.code = 0;
1148         icmp_param.skb             = skb;
1149         icmp_param.offset          = 0;
1150         icmp_param.data_len        = 0;
1151         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1152         icmp_reply(&icmp_param, skb);
1153         return SKB_NOT_DROPPED_YET;
1154
1155 out_err:
1156         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1157         return SKB_DROP_REASON_PKT_TOO_SMALL;
1158 }
1159
1160 static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1161 {
1162         /* pretend it was a success */
1163         return SKB_NOT_DROPPED_YET;
1164 }
1165
1166 /*
1167  *      Deal with incoming ICMP packets.
1168  */
1169 int icmp_rcv(struct sk_buff *skb)
1170 {
1171         enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1172         struct rtable *rt = skb_rtable(skb);
1173         struct net *net = dev_net(rt->dst.dev);
1174         struct icmphdr *icmph;
1175
1176         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1177                 struct sec_path *sp = skb_sec_path(skb);
1178                 int nh;
1179
1180                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1181                                  XFRM_STATE_ICMP)) {
1182                         reason = SKB_DROP_REASON_XFRM_POLICY;
1183                         goto drop;
1184                 }
1185
1186                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1187                         goto drop;
1188
1189                 nh = skb_network_offset(skb);
1190                 skb_set_network_header(skb, sizeof(*icmph));
1191
1192                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1193                                                 skb)) {
1194                         reason = SKB_DROP_REASON_XFRM_POLICY;
1195                         goto drop;
1196                 }
1197
1198                 skb_set_network_header(skb, nh);
1199         }
1200
1201         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1202
1203         if (skb_checksum_simple_validate(skb))
1204                 goto csum_error;
1205
1206         if (!pskb_pull(skb, sizeof(*icmph)))
1207                 goto error;
1208
1209         icmph = icmp_hdr(skb);
1210
1211         ICMPMSGIN_INC_STATS(net, icmph->type);
1212
1213         /* Check for ICMP Extended Echo (PROBE) messages */
1214         if (icmph->type == ICMP_EXT_ECHO) {
1215                 /* We can't use icmp_pointers[].handler() because it is an array of
1216                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1217                  */
1218                 reason = icmp_echo(skb);
1219                 goto reason_check;
1220         }
1221
1222         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1223                 reason = ping_rcv(skb);
1224                 goto reason_check;
1225         }
1226
1227         /*
1228          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1229          *
1230          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1231          *                discarded.
1232          */
1233         if (icmph->type > NR_ICMP_TYPES) {
1234                 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1235                 goto error;
1236         }
1237
1238         /*
1239          *      Parse the ICMP message
1240          */
1241
1242         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1243                 /*
1244                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1245                  *        silently ignored (we let user decide with a sysctl).
1246                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1247                  *        discarded if to broadcast/multicast.
1248                  */
1249                 if ((icmph->type == ICMP_ECHO ||
1250                      icmph->type == ICMP_TIMESTAMP) &&
1251                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1252                         reason = SKB_DROP_REASON_INVALID_PROTO;
1253                         goto error;
1254                 }
1255                 if (icmph->type != ICMP_ECHO &&
1256                     icmph->type != ICMP_TIMESTAMP &&
1257                     icmph->type != ICMP_ADDRESS &&
1258                     icmph->type != ICMP_ADDRESSREPLY) {
1259                         reason = SKB_DROP_REASON_INVALID_PROTO;
1260                         goto error;
1261                 }
1262         }
1263
1264         reason = icmp_pointers[icmph->type].handler(skb);
1265 reason_check:
1266         if (!reason)  {
1267                 consume_skb(skb);
1268                 return NET_RX_SUCCESS;
1269         }
1270
1271 drop:
1272         kfree_skb_reason(skb, reason);
1273         return NET_RX_DROP;
1274 csum_error:
1275         reason = SKB_DROP_REASON_ICMP_CSUM;
1276         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1277 error:
1278         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1279         goto drop;
1280 }
1281
1282 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1283 {
1284         struct icmp_extobj_hdr *objh, _objh;
1285         struct icmp_ext_hdr *exth, _exth;
1286         u16 olen;
1287
1288         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1289         if (!exth)
1290                 return false;
1291         if (exth->version != 2)
1292                 return true;
1293
1294         if (exth->checksum &&
1295             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1296                 return false;
1297
1298         off += sizeof(_exth);
1299         while (off < skb->len) {
1300                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1301                 if (!objh)
1302                         return false;
1303
1304                 olen = ntohs(objh->length);
1305                 if (olen < sizeof(_objh))
1306                         return false;
1307
1308                 off += olen;
1309                 if (off > skb->len)
1310                         return false;
1311         }
1312
1313         return true;
1314 }
1315
1316 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1317                            struct sock_ee_data_rfc4884 *out,
1318                            int thlen, int off)
1319 {
1320         int hlen;
1321
1322         /* original datagram headers: end of icmph to payload (skb->data) */
1323         hlen = -skb_transport_offset(skb) - thlen;
1324
1325         /* per rfc 4884: minimal datagram length of 128 bytes */
1326         if (off < 128 || off < hlen)
1327                 return;
1328
1329         /* kernel has stripped headers: return payload offset in bytes */
1330         off -= hlen;
1331         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1332                 return;
1333
1334         out->len = off;
1335
1336         if (!ip_icmp_error_rfc4884_validate(skb, off))
1337                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1338 }
1339 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1340
1341 int icmp_err(struct sk_buff *skb, u32 info)
1342 {
1343         struct iphdr *iph = (struct iphdr *)skb->data;
1344         int offset = iph->ihl<<2;
1345         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1346         int type = icmp_hdr(skb)->type;
1347         int code = icmp_hdr(skb)->code;
1348         struct net *net = dev_net(skb->dev);
1349
1350         /*
1351          * Use ping_err to handle all icmp errors except those
1352          * triggered by ICMP_ECHOREPLY which sent from kernel.
1353          */
1354         if (icmph->type != ICMP_ECHOREPLY) {
1355                 ping_err(skb, offset, info);
1356                 return 0;
1357         }
1358
1359         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1360                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1361         else if (type == ICMP_REDIRECT)
1362                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1363
1364         return 0;
1365 }
1366
1367 /*
1368  *      This table is the definition of how we handle ICMP.
1369  */
1370 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1371         [ICMP_ECHOREPLY] = {
1372                 .handler = ping_rcv,
1373         },
1374         [1] = {
1375                 .handler = icmp_discard,
1376                 .error = 1,
1377         },
1378         [2] = {
1379                 .handler = icmp_discard,
1380                 .error = 1,
1381         },
1382         [ICMP_DEST_UNREACH] = {
1383                 .handler = icmp_unreach,
1384                 .error = 1,
1385         },
1386         [ICMP_SOURCE_QUENCH] = {
1387                 .handler = icmp_unreach,
1388                 .error = 1,
1389         },
1390         [ICMP_REDIRECT] = {
1391                 .handler = icmp_redirect,
1392                 .error = 1,
1393         },
1394         [6] = {
1395                 .handler = icmp_discard,
1396                 .error = 1,
1397         },
1398         [7] = {
1399                 .handler = icmp_discard,
1400                 .error = 1,
1401         },
1402         [ICMP_ECHO] = {
1403                 .handler = icmp_echo,
1404         },
1405         [9] = {
1406                 .handler = icmp_discard,
1407                 .error = 1,
1408         },
1409         [10] = {
1410                 .handler = icmp_discard,
1411                 .error = 1,
1412         },
1413         [ICMP_TIME_EXCEEDED] = {
1414                 .handler = icmp_unreach,
1415                 .error = 1,
1416         },
1417         [ICMP_PARAMETERPROB] = {
1418                 .handler = icmp_unreach,
1419                 .error = 1,
1420         },
1421         [ICMP_TIMESTAMP] = {
1422                 .handler = icmp_timestamp,
1423         },
1424         [ICMP_TIMESTAMPREPLY] = {
1425                 .handler = icmp_discard,
1426         },
1427         [ICMP_INFO_REQUEST] = {
1428                 .handler = icmp_discard,
1429         },
1430         [ICMP_INFO_REPLY] = {
1431                 .handler = icmp_discard,
1432         },
1433         [ICMP_ADDRESS] = {
1434                 .handler = icmp_discard,
1435         },
1436         [ICMP_ADDRESSREPLY] = {
1437                 .handler = icmp_discard,
1438         },
1439 };
1440
1441 static int __net_init icmp_sk_init(struct net *net)
1442 {
1443         /* Control parameters for ECHO replies. */
1444         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1445         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1446         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1447
1448         /* Control parameter - ignore bogus broadcast responses? */
1449         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1450
1451         /*
1452          *      Configurable global rate limit.
1453          *
1454          *      ratelimit defines tokens/packet consumed for dst->rate_token
1455          *      bucket ratemask defines which icmp types are ratelimited by
1456          *      setting it's bit position.
1457          *
1458          *      default:
1459          *      dest unreachable (3), source quench (4),
1460          *      time exceeded (11), parameter problem (12)
1461          */
1462
1463         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1464         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1465         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1466
1467         return 0;
1468 }
1469
1470 static struct pernet_operations __net_initdata icmp_sk_ops = {
1471        .init = icmp_sk_init,
1472 };
1473
1474 int __init icmp_init(void)
1475 {
1476         int err, i;
1477
1478         for_each_possible_cpu(i) {
1479                 struct sock *sk;
1480
1481                 err = inet_ctl_sock_create(&sk, PF_INET,
1482                                            SOCK_RAW, IPPROTO_ICMP, &init_net);
1483                 if (err < 0)
1484                         return err;
1485
1486                 per_cpu(ipv4_icmp_sk, i) = sk;
1487
1488                 /* Enough space for 2 64K ICMP packets, including
1489                  * sk_buff/skb_shared_info struct overhead.
1490                  */
1491                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1492
1493                 /*
1494                  * Speedup sock_wfree()
1495                  */
1496                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1497                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1498         }
1499         return register_pernet_subsys(&icmp_sk_ops);
1500 }