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 #include <net/addrconf.h>
  96
  97 /*
  98  *      Build xmit assembly blocks
  99  */
 100
 101 struct icmp_bxm {
 102         struct sk_buff *skb;
 103         int offset;
 104         int data_len;
 105
 106         struct {
 107                 struct icmphdr icmph;
 108                 __be32         times[3];
 109         } data;
 110         int head_len;
 111         struct ip_options_data replyopts;
 112 };
 113
 114 /* An array of errno for error messages from dest unreach. */
 115 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
 116
 117 const struct icmp_err icmp_err_convert[] = {
 118         {
 119                 .errno = ENETUNREACH,   /* ICMP_NET_UNREACH */
 120                 .fatal = 0,
 121         },
 122         {
 123                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNREACH */
 124                 .fatal = 0,
 125         },
 126         {
 127                 .errno = ENOPROTOOPT    /* ICMP_PROT_UNREACH */,
 128                 .fatal = 1,
 129         },
 130         {
 131                 .errno = ECONNREFUSED,  /* ICMP_PORT_UNREACH */
 132                 .fatal = 1,
 133         },
 134         {
 135                 .errno = EMSGSIZE,      /* ICMP_FRAG_NEEDED */
 136                 .fatal = 0,
 137         },
 138         {
 139                 .errno = EOPNOTSUPP,    /* ICMP_SR_FAILED */
 140                 .fatal = 0,
 141         },
 142         {
 143                 .errno = ENETUNREACH,   /* ICMP_NET_UNKNOWN */
 144                 .fatal = 1,
 145         },
 146         {
 147                 .errno = EHOSTDOWN,     /* ICMP_HOST_UNKNOWN */
 148                 .fatal = 1,
 149         },
 150         {
 151                 .errno = ENONET,        /* ICMP_HOST_ISOLATED */
 152                 .fatal = 1,
 153         },
 154         {
 155                 .errno = ENETUNREACH,   /* ICMP_NET_ANO */
 156                 .fatal = 1,
 157         },
 158         {
 159                 .errno = EHOSTUNREACH,  /* ICMP_HOST_ANO */
 160                 .fatal = 1,
 161         },
 162         {
 163                 .errno = ENETUNREACH,   /* ICMP_NET_UNR_TOS */
 164                 .fatal = 0,
 165         },
 166         {
 167                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNR_TOS */
 168                 .fatal = 0,
 169         },
 170         {
 171                 .errno = EHOSTUNREACH,  /* ICMP_PKT_FILTERED */
 172                 .fatal = 1,
 173         },
 174         {
 175                 .errno = EHOSTUNREACH,  /* ICMP_PREC_VIOLATION */
 176                 .fatal = 1,
 177         },
 178         {
 179                 .errno = EHOSTUNREACH,  /* ICMP_PREC_CUTOFF */
 180                 .fatal = 1,
 181         },
 182 };
 183 EXPORT_SYMBOL(icmp_err_convert);
 184
 185 /*
 186  *      ICMP control array. This specifies what to do with each ICMP.
 187  */
 188
 189 struct icmp_control {
 190         enum skb_drop_reason (*handler)(struct sk_buff *skb);
 191         short   error;          /* This ICMP is classed as an error message */
 192 };
 193
 194 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
 195
 196 static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk);
 197
 198 /* Called with BH disabled */
 199 static inline struct sock *icmp_xmit_lock(struct net *net)
 200 {
 201         struct sock *sk;
 202
 203         sk = this_cpu_read(ipv4_icmp_sk);
 204
 205         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
 206                 /* This can happen if the output path signals a
 207                  * dst_link_failure() for an outgoing ICMP packet.
 208                  */
 209                 return NULL;
 210         }
 211         sock_net_set(sk, net);
 212         return sk;
 213 }
 214
 215 static inline void icmp_xmit_unlock(struct sock *sk)
 216 {
 217         sock_net_set(sk, &init_net);
 218         spin_unlock(&sk->sk_lock.slock);
 219 }
 220
 221 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
 222 int sysctl_icmp_msgs_burst __read_mostly = 50;
 223
 224 static struct {
 225         spinlock_t      lock;
 226         u32             credit;
 227         u32             stamp;
 228 } icmp_global = {
 229         .lock           = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
 230 };
 231
 232 /**
 233  * icmp_global_allow - Are we allowed to send one more ICMP message ?
 234  *
 235  * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
 236  * Returns false if we reached the limit and can not send another packet.
 237  * Note: called with BH disabled
 238  */
 239 bool icmp_global_allow(void)
 240 {
 241         u32 credit, delta, incr = 0, now = (u32)jiffies;
 242         bool rc = false;
 243
 244         /* Check if token bucket is empty and cannot be refilled
 245          * without taking the spinlock. The READ_ONCE() are paired
 246          * with the following WRITE_ONCE() in this same function.
 247          */
 248         if (!READ_ONCE(icmp_global.credit)) {
 249                 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
 250                 if (delta < HZ / 50)
 251                         return false;
 252         }
 253
 254         spin_lock(&icmp_global.lock);
 255         delta = min_t(u32, now - icmp_global.stamp, HZ);
 256         if (delta >= HZ / 50) {
 257                 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
 258                 if (incr)
 259                         WRITE_ONCE(icmp_global.stamp, now);
 260         }
 261         credit = min_t(u32, icmp_global.credit + incr,
 262                        READ_ONCE(sysctl_icmp_msgs_burst));
 263         if (credit) {
 264                 /* We want to use a credit of one in average, but need to randomize
 265                  * it for security reasons.
 266                  */
 267                 credit = max_t(int, credit - get_random_u32_below(3), 0);
 268                 rc = true;
 269         }
 270         WRITE_ONCE(icmp_global.credit, credit);
 271         spin_unlock(&icmp_global.lock);
 272         return rc;
 273 }
 274 EXPORT_SYMBOL(icmp_global_allow);
 275
 276 static bool icmpv4_mask_allow(struct net *net, int type, int code)
 277 {
 278         if (type > NR_ICMP_TYPES)
 279                 return true;
 280
 281         /* Don't limit PMTU discovery. */
 282         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 283                 return true;
 284
 285         /* Limit if icmp type is enabled in ratemask. */
 286         if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
 287                 return true;
 288
 289         return false;
 290 }
 291
 292 static bool icmpv4_global_allow(struct net *net, int type, int code)
 293 {
 294         if (icmpv4_mask_allow(net, type, code))
 295                 return true;
 296
 297         if (icmp_global_allow())
 298                 return true;
 299
 300         __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
 301         return false;
 302 }
 303
 304 /*
 305  *      Send an ICMP frame.
 306  */
 307
 308 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
 309                                struct flowi4 *fl4, int type, int code)
 310 {
 311         struct dst_entry *dst = &rt->dst;
 312         struct inet_peer *peer;
 313         bool rc = true;
 314         int vif;
 315
 316         if (icmpv4_mask_allow(net, type, code))
 317                 goto out;
 318
 319         /* No rate limit on loopback */
 320         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
 321                 goto out;
 322
 323         vif = l3mdev_master_ifindex(dst->dev);
 324         peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
 325         rc = inet_peer_xrlim_allow(peer,
 326                                    READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
 327         if (peer)
 328                 inet_putpeer(peer);
 329 out:
 330         if (!rc)
 331                 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST);
 332         return rc;
 333 }
 334
 335 /*
 336  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
 337  */
 338 void icmp_out_count(struct net *net, unsigned char type)
 339 {
 340         ICMPMSGOUT_INC_STATS(net, type);
 341         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
 342 }
 343
 344 /*
 345  *      Checksum each fragment, and on the first include the headers and final
 346  *      checksum.
 347  */
 348 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
 349                           struct sk_buff *skb)
 350 {
 351         struct icmp_bxm *icmp_param = from;
 352         __wsum csum;
 353
 354         csum = skb_copy_and_csum_bits(icmp_param->skb,
 355                                       icmp_param->offset + offset,
 356                                       to, len);
 357
 358         skb->csum = csum_block_add(skb->csum, csum, odd);
 359         if (icmp_pointers[icmp_param->data.icmph.type].error)
 360                 nf_ct_attach(skb, icmp_param->skb);
 361         return 0;
 362 }
 363
 364 static void icmp_push_reply(struct sock *sk,
 365                             struct icmp_bxm *icmp_param,
 366                             struct flowi4 *fl4,
 367                             struct ipcm_cookie *ipc, struct rtable **rt)
 368 {
 369         struct sk_buff *skb;
 370
 371         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
 372                            icmp_param->data_len+icmp_param->head_len,
 373                            icmp_param->head_len,
 374                            ipc, rt, MSG_DONTWAIT) < 0) {
 375                 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
 376                 ip_flush_pending_frames(sk);
 377         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
 378                 struct icmphdr *icmph = icmp_hdr(skb);
 379                 __wsum csum;
 380                 struct sk_buff *skb1;
 381
 382                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
 383                                                  (char *)icmph,
 384                                                  icmp_param->head_len);
 385                 skb_queue_walk(&sk->sk_write_queue, skb1) {
 386                         csum = csum_add(csum, skb1->csum);
 387                 }
 388                 icmph->checksum = csum_fold(csum);
 389                 skb->ip_summed = CHECKSUM_NONE;
 390                 ip_push_pending_frames(sk, fl4);
 391         }
 392 }
 393
 394 /*
 395  *      Driving logic for building and sending ICMP messages.
 396  */
 397
 398 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 399 {
 400         struct ipcm_cookie ipc;
 401         struct rtable *rt = skb_rtable(skb);
 402         struct net *net = dev_net(rt->dst.dev);
 403         struct flowi4 fl4;
 404         struct sock *sk;
 405         struct inet_sock *inet;
 406         __be32 daddr, saddr;
 407         u32 mark = IP4_REPLY_MARK(net, skb->mark);
 408         int type = icmp_param->data.icmph.type;
 409         int code = icmp_param->data.icmph.code;
 410
 411         if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
 412                 return;
 413
 414         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 415         local_bh_disable();
 416
 417         /* global icmp_msgs_per_sec */
 418         if (!icmpv4_global_allow(net, type, code))
 419                 goto out_bh_enable;
 420
 421         sk = icmp_xmit_lock(net);
 422         if (!sk)
 423                 goto out_bh_enable;
 424         inet = inet_sk(sk);
 425
 426         icmp_param->data.icmph.checksum = 0;
 427
 428         ipcm_init(&ipc);
 429         inet->tos = ip_hdr(skb)->tos;
 430         ipc.sockc.mark = mark;
 431         daddr = ipc.addr = ip_hdr(skb)->saddr;
 432         saddr = fib_compute_spec_dst(skb);
 433
 434         if (icmp_param->replyopts.opt.opt.optlen) {
 435                 ipc.opt = &icmp_param->replyopts.opt;
 436                 if (ipc.opt->opt.srr)
 437                         daddr = icmp_param->replyopts.opt.opt.faddr;
 438         }
 439         memset(&fl4, 0, sizeof(fl4));
 440         fl4.daddr = daddr;
 441         fl4.saddr = saddr;
 442         fl4.flowi4_mark = mark;
 443         fl4.flowi4_uid = sock_net_uid(net, NULL);
 444         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
 445         fl4.flowi4_proto = IPPROTO_ICMP;
 446         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 447         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
 448         rt = ip_route_output_key(net, &fl4);
 449         if (IS_ERR(rt))
 450                 goto out_unlock;
 451         if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 452                 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
 453         ip_rt_put(rt);
 454 out_unlock:
 455         icmp_xmit_unlock(sk);
 456 out_bh_enable:
 457         local_bh_enable();
 458 }
 459
 460 /*
 461  * The device used for looking up which routing table to use for sending an ICMP
 462  * error is preferably the source whenever it is set, which should ensure the
 463  * icmp error can be sent to the source host, else lookup using the routing
 464  * table of the destination device, else use the main routing table (index 0).
 465  */
 466 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
 467 {
 468         struct net_device *route_lookup_dev = NULL;
 469
 470         if (skb->dev)
 471                 route_lookup_dev = skb->dev;
 472         else if (skb_dst(skb))
 473                 route_lookup_dev = skb_dst(skb)->dev;
 474         return route_lookup_dev;
 475 }
 476
 477 static struct rtable *icmp_route_lookup(struct net *net,
 478                                         struct flowi4 *fl4,
 479                                         struct sk_buff *skb_in,
 480                                         const struct iphdr *iph,
 481                                         __be32 saddr, u8 tos, u32 mark,
 482                                         int type, int code,
 483                                         struct icmp_bxm *param)
 484 {
 485         struct net_device *route_lookup_dev;
 486         struct rtable *rt, *rt2;
 487         struct flowi4 fl4_dec;
 488         int err;
 489
 490         memset(fl4, 0, sizeof(*fl4));
 491         fl4->daddr = (param->replyopts.opt.opt.srr ?
 492                       param->replyopts.opt.opt.faddr : iph->saddr);
 493         fl4->saddr = saddr;
 494         fl4->flowi4_mark = mark;
 495         fl4->flowi4_uid = sock_net_uid(net, NULL);
 496         fl4->flowi4_tos = RT_TOS(tos);
 497         fl4->flowi4_proto = IPPROTO_ICMP;
 498         fl4->fl4_icmp_type = type;
 499         fl4->fl4_icmp_code = code;
 500         route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
 501         fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
 502
 503         security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
 504         rt = ip_route_output_key_hash(net, fl4, skb_in);
 505         if (IS_ERR(rt))
 506                 return rt;
 507
 508         /* No need to clone since we're just using its address. */
 509         rt2 = rt;
 510
 511         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
 512                                            flowi4_to_flowi(fl4), NULL, 0);
 513         if (!IS_ERR(rt)) {
 514                 if (rt != rt2)
 515                         return rt;
 516         } else if (PTR_ERR(rt) == -EPERM) {
 517                 rt = NULL;
 518         } else
 519                 return rt;
 520
 521         err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
 522         if (err)
 523                 goto relookup_failed;
 524
 525         if (inet_addr_type_dev_table(net, route_lookup_dev,
 526                                      fl4_dec.saddr) == RTN_LOCAL) {
 527                 rt2 = __ip_route_output_key(net, &fl4_dec);
 528                 if (IS_ERR(rt2))
 529                         err = PTR_ERR(rt2);
 530         } else {
 531                 struct flowi4 fl4_2 = {};
 532                 unsigned long orefdst;
 533
 534                 fl4_2.daddr = fl4_dec.saddr;
 535                 rt2 = ip_route_output_key(net, &fl4_2);
 536                 if (IS_ERR(rt2)) {
 537                         err = PTR_ERR(rt2);
 538                         goto relookup_failed;
 539                 }
 540                 /* Ugh! */
 541                 orefdst = skb_in->_skb_refdst; /* save old refdst */
 542                 skb_dst_set(skb_in, NULL);
 543                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
 544                                      RT_TOS(tos), rt2->dst.dev);
 545
 546                 dst_release(&rt2->dst);
 547                 rt2 = skb_rtable(skb_in);
 548                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
 549         }
 550
 551         if (err)
 552                 goto relookup_failed;
 553
 554         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
 555                                             flowi4_to_flowi(&fl4_dec), NULL,
 556                                             XFRM_LOOKUP_ICMP);
 557         if (!IS_ERR(rt2)) {
 558                 dst_release(&rt->dst);
 559                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
 560                 rt = rt2;
 561         } else if (PTR_ERR(rt2) == -EPERM) {
 562                 if (rt)
 563                         dst_release(&rt->dst);
 564                 return rt2;
 565         } else {
 566                 err = PTR_ERR(rt2);
 567                 goto relookup_failed;
 568         }
 569         return rt;
 570
 571 relookup_failed:
 572         if (rt)
 573                 return rt;
 574         return ERR_PTR(err);
 575 }
 576
 577 /*
 578  *      Send an ICMP message in response to a situation
 579  *
 580  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
 581  *                MAY send more (we do).
 582  *                      MUST NOT change this header information.
 583  *                      MUST NOT reply to a multicast/broadcast IP address.
 584  *                      MUST NOT reply to a multicast/broadcast MAC address.
 585  *                      MUST reply to only the first fragment.
 586  */
 587
 588 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
 589                  const struct ip_options *opt)
 590 {
 591         struct iphdr *iph;
 592         int room;
 593         struct icmp_bxm icmp_param;
 594         struct rtable *rt = skb_rtable(skb_in);
 595         struct ipcm_cookie ipc;
 596         struct flowi4 fl4;
 597         __be32 saddr;
 598         u8  tos;
 599         u32 mark;
 600         struct net *net;
 601         struct sock *sk;
 602
 603         if (!rt)
 604                 goto out;
 605
 606         if (rt->dst.dev)
 607                 net = dev_net(rt->dst.dev);
 608         else if (skb_in->dev)
 609                 net = dev_net(skb_in->dev);
 610         else
 611                 goto out;
 612
 613         /*
 614          *      Find the original header. It is expected to be valid, of course.
 615          *      Check this, icmp_send is called from the most obscure devices
 616          *      sometimes.
 617          */
 618         iph = ip_hdr(skb_in);
 619
 620         if ((u8 *)iph < skb_in->head ||
 621             (skb_network_header(skb_in) + sizeof(*iph)) >
 622             skb_tail_pointer(skb_in))
 623                 goto out;
 624
 625         /*
 626          *      No replies to physical multicast/broadcast
 627          */
 628         if (skb_in->pkt_type != PACKET_HOST)
 629                 goto out;
 630
 631         /*
 632          *      Now check at the protocol level
 633          */
 634         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
 635                 goto out;
 636
 637         /*
 638          *      Only reply to fragment 0. We byte re-order the constant
 639          *      mask for efficiency.
 640          */
 641         if (iph->frag_off & htons(IP_OFFSET))
 642                 goto out;
 643
 644         /*
 645          *      If we send an ICMP error to an ICMP error a mess would result..
 646          */
 647         if (icmp_pointers[type].error) {
 648                 /*
 649                  *      We are an error, check if we are replying to an
 650                  *      ICMP error
 651                  */
 652                 if (iph->protocol == IPPROTO_ICMP) {
 653                         u8 _inner_type, *itp;
 654
 655                         itp = skb_header_pointer(skb_in,
 656                                                  skb_network_header(skb_in) +
 657                                                  (iph->ihl << 2) +
 658                                                  offsetof(struct icmphdr,
 659                                                           type) -
 660                                                  skb_in->data,
 661                                                  sizeof(_inner_type),
 662                                                  &_inner_type);
 663                         if (!itp)
 664                                 goto out;
 665
 666                         /*
 667                          *      Assume any unknown ICMP type is an error. This
 668                          *      isn't specified by the RFC, but think about it..
 669                          */
 670                         if (*itp > NR_ICMP_TYPES ||
 671                             icmp_pointers[*itp].error)
 672                                 goto out;
 673                 }
 674         }
 675
 676         /* Needed by both icmp_global_allow and icmp_xmit_lock */
 677         local_bh_disable();
 678
 679         /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
 680          * incoming dev is loopback.  If outgoing dev change to not be
 681          * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
 682          */
 683         if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
 684               !icmpv4_global_allow(net, type, code))
 685                 goto out_bh_enable;
 686
 687         sk = icmp_xmit_lock(net);
 688         if (!sk)
 689                 goto out_bh_enable;
 690
 691         /*
 692          *      Construct source address and options.
 693          */
 694
 695         saddr = iph->daddr;
 696         if (!(rt->rt_flags & RTCF_LOCAL)) {
 697                 struct net_device *dev = NULL;
 698
 699                 rcu_read_lock();
 700                 if (rt_is_input_route(rt) &&
 701                     READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
 702                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
 703
 704                 if (dev)
 705                         saddr = inet_select_addr(dev, iph->saddr,
 706                                                  RT_SCOPE_LINK);
 707                 else
 708                         saddr = 0;
 709                 rcu_read_unlock();
 710         }
 711
 712         tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
 713                                            IPTOS_PREC_INTERNETCONTROL) :
 714                                            iph->tos;
 715         mark = IP4_REPLY_MARK(net, skb_in->mark);
 716
 717         if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
 718                 goto out_unlock;
 719
 720
 721         /*
 722          *      Prepare data for ICMP header.
 723          */
 724
 725         icmp_param.data.icmph.type       = type;
 726         icmp_param.data.icmph.code       = code;
 727         icmp_param.data.icmph.un.gateway = info;
 728         icmp_param.data.icmph.checksum   = 0;
 729         icmp_param.skb    = skb_in;
 730         icmp_param.offset = skb_network_offset(skb_in);
 731         inet_sk(sk)->tos = tos;
 732         ipcm_init(&ipc);
 733         ipc.addr = iph->saddr;
 734         ipc.opt = &icmp_param.replyopts.opt;
 735         ipc.sockc.mark = mark;
 736
 737         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
 738                                type, code, &icmp_param);
 739         if (IS_ERR(rt))
 740                 goto out_unlock;
 741
 742         /* peer icmp_ratelimit */
 743         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
 744                 goto ende;
 745
 746         /* RFC says return as much as we can without exceeding 576 bytes. */
 747
 748         room = dst_mtu(&rt->dst);
 749         if (room > 576)
 750                 room = 576;
 751         room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
 752         room -= sizeof(struct icmphdr);
 753         /* Guard against tiny mtu. We need to include at least one
 754          * IP network header for this message to make any sense.
 755          */
 756         if (room <= (int)sizeof(struct iphdr))
 757                 goto ende;
 758
 759         icmp_param.data_len = skb_in->len - icmp_param.offset;
 760         if (icmp_param.data_len > room)
 761                 icmp_param.data_len = room;
 762         icmp_param.head_len = sizeof(struct icmphdr);
 763
 764         /* if we don't have a source address at this point, fall back to the
 765          * dummy address instead of sending out a packet with a source address
 766          * of 0.0.0.0
 767          */
 768         if (!fl4.saddr)
 769                 fl4.saddr = htonl(INADDR_DUMMY);
 770
 771         icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
 772 ende:
 773         ip_rt_put(rt);
 774 out_unlock:
 775         icmp_xmit_unlock(sk);
 776 out_bh_enable:
 777         local_bh_enable();
 778 out:;
 779 }
 780 EXPORT_SYMBOL(__icmp_send);
 781
 782 #if IS_ENABLED(CONFIG_NF_NAT)
 783 #include <net/netfilter/nf_conntrack.h>
 784 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 785 {
 786         struct sk_buff *cloned_skb = NULL;
 787         struct ip_options opts = { 0 };
 788         enum ip_conntrack_info ctinfo;
 789         struct nf_conn *ct;
 790         __be32 orig_ip;
 791
 792         ct = nf_ct_get(skb_in, &ctinfo);
 793         if (!ct || !(ct->status & IPS_SRC_NAT)) {
 794                 __icmp_send(skb_in, type, code, info, &opts);
 795                 return;
 796         }
 797
 798         if (skb_shared(skb_in))
 799                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
 800
 801         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
 802             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
 803             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
 804             skb_network_offset(skb_in) + sizeof(struct iphdr))))
 805                 goto out;
 806
 807         orig_ip = ip_hdr(skb_in)->saddr;
 808         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
 809         __icmp_send(skb_in, type, code, info, &opts);
 810         ip_hdr(skb_in)->saddr = orig_ip;
 811 out:
 812         consume_skb(cloned_skb);
 813 }
 814 EXPORT_SYMBOL(icmp_ndo_send);
 815 #endif
 816
 817 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
 818 {
 819         const struct iphdr *iph = (const struct iphdr *)skb->data;
 820         const struct net_protocol *ipprot;
 821         int protocol = iph->protocol;
 822
 823         /* Checkin full IP header plus 8 bytes of protocol to
 824          * avoid additional coding at protocol handlers.
 825          */
 826         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
 827                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 828                 return;
 829         }
 830
 831         raw_icmp_error(skb, protocol, info);
 832
 833         ipprot = rcu_dereference(inet_protos[protocol]);
 834         if (ipprot && ipprot->err_handler)
 835                 ipprot->err_handler(skb, info);
 836 }
 837
 838 static bool icmp_tag_validation(int proto)
 839 {
 840         bool ok;
 841
 842         rcu_read_lock();
 843         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
 844         rcu_read_unlock();
 845         return ok;
 846 }
 847
 848 /*
 849  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
 850  *      ICMP_PARAMETERPROB.
 851  */
 852
 853 static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
 854 {
 855         enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
 856         const struct iphdr *iph;
 857         struct icmphdr *icmph;
 858         struct net *net;
 859         u32 info = 0;
 860
 861         net = dev_net(skb_dst(skb)->dev);
 862
 863         /*
 864          *      Incomplete header ?
 865          *      Only checks for the IP header, there should be an
 866          *      additional check for longer headers in upper levels.
 867          */
 868
 869         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 870                 goto out_err;
 871
 872         icmph = icmp_hdr(skb);
 873         iph   = (const struct iphdr *)skb->data;
 874
 875         if (iph->ihl < 5)  { /* Mangled header, drop. */
 876                 reason = SKB_DROP_REASON_IP_INHDR;
 877                 goto out_err;
 878         }
 879
 880         switch (icmph->type) {
 881         case ICMP_DEST_UNREACH:
 882                 switch (icmph->code & 15) {
 883                 case ICMP_NET_UNREACH:
 884                 case ICMP_HOST_UNREACH:
 885                 case ICMP_PROT_UNREACH:
 886                 case ICMP_PORT_UNREACH:
 887                         break;
 888                 case ICMP_FRAG_NEEDED:
 889                         /* for documentation of the ip_no_pmtu_disc
 890                          * values please see
 891                          * Documentation/networking/ip-sysctl.rst
 892                          */
 893                         switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
 894                         default:
 895                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
 896                                                     &iph->daddr);
 897                                 break;
 898                         case 2:
 899                                 goto out;
 900                         case 3:
 901                                 if (!icmp_tag_validation(iph->protocol))
 902                                         goto out;
 903                                 fallthrough;
 904                         case 0:
 905                                 info = ntohs(icmph->un.frag.mtu);
 906                         }
 907                         break;
 908                 case ICMP_SR_FAILED:
 909                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
 910                                             &iph->daddr);
 911                         break;
 912                 default:
 913                         break;
 914                 }
 915                 if (icmph->code > NR_ICMP_UNREACH)
 916                         goto out;
 917                 break;
 918         case ICMP_PARAMETERPROB:
 919                 info = ntohl(icmph->un.gateway) >> 24;
 920                 break;
 921         case ICMP_TIME_EXCEEDED:
 922                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
 923                 if (icmph->code == ICMP_EXC_FRAGTIME)
 924                         goto out;
 925                 break;
 926         }
 927
 928         /*
 929          *      Throw it at our lower layers
 930          *
 931          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
 932          *                header.
 933          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
 934          *                transport layer.
 935          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
 936          *                transport layer.
 937          */
 938
 939         /*
 940          *      Check the other end isn't violating RFC 1122. Some routers send
 941          *      bogus responses to broadcast frames. If you see this message
 942          *      first check your netmask matches at both ends, if it does then
 943          *      get the other vendor to fix their kit.
 944          */
 945
 946         if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
 947             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
 948                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
 949                                      &ip_hdr(skb)->saddr,
 950                                      icmph->type, icmph->code,
 951                                      &iph->daddr, skb->dev->name);
 952                 goto out;
 953         }
 954
 955         icmp_socket_deliver(skb, info);
 956
 957 out:
 958         return reason;
 959 out_err:
 960         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
 961         return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
 962 }
 963
 964
 965 /*
 966  *      Handle ICMP_REDIRECT.
 967  */
 968
 969 static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
 970 {
 971         if (skb->len < sizeof(struct iphdr)) {
 972                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
 973                 return SKB_DROP_REASON_PKT_TOO_SMALL;
 974         }
 975
 976         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
 977                 /* there aught to be a stat */
 978                 return SKB_DROP_REASON_NOMEM;
 979         }
 980
 981         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
 982         return SKB_NOT_DROPPED_YET;
 983 }
 984
 985 /*
 986  *      Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
 987  *
 988  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
 989  *                requests.
 990  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
 991  *                included in the reply.
 992  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
 993  *                echo requests, MUST have default=NOT.
 994  *      RFC 8335: 8 MUST have a config option to enable/disable ICMP
 995  *                Extended Echo Functionality, MUST be disabled by default
 996  *      See also WRT handling of options once they are done and working.
 997  */
 998
 999 static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
1000 {
1001         struct icmp_bxm icmp_param;
1002         struct net *net;
1003
1004         net = dev_net(skb_dst(skb)->dev);
1005         /* should there be an ICMP stat for ignored echos? */
1006         if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1007                 return SKB_NOT_DROPPED_YET;
1008
1009         icmp_param.data.icmph      = *icmp_hdr(skb);
1010         icmp_param.skb             = skb;
1011         icmp_param.offset          = 0;
1012         icmp_param.data_len        = skb->len;
1013         icmp_param.head_len        = sizeof(struct icmphdr);
1014
1015         if (icmp_param.data.icmph.type == ICMP_ECHO)
1016                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1017         else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1018                 return SKB_NOT_DROPPED_YET;
1019
1020         icmp_reply(&icmp_param, skb);
1021         return SKB_NOT_DROPPED_YET;
1022 }
1023
1024 /*      Helper for icmp_echo and icmpv6_echo_reply.
1025  *      Searches for net_device that matches PROBE interface identifier
1026  *              and builds PROBE reply message in icmphdr.
1027  *
1028  *      Returns false if PROBE responses are disabled via sysctl
1029  */
1030
1031 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1032 {
1033         struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1034         struct icmp_ext_echo_iio *iio, _iio;
1035         struct net *net = dev_net(skb->dev);
1036         struct inet6_dev *in6_dev;
1037         struct in_device *in_dev;
1038         struct net_device *dev;
1039         char buff[IFNAMSIZ];
1040         u16 ident_len;
1041         u8 status;
1042
1043         if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1044                 return false;
1045
1046         /* We currently only support probing interfaces on the proxy node
1047          * Check to ensure L-bit is set
1048          */
1049         if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1050                 return false;
1051         /* Clear status bits in reply message */
1052         icmphdr->un.echo.sequence &= htons(0xFF00);
1053         if (icmphdr->type == ICMP_EXT_ECHO)
1054                 icmphdr->type = ICMP_EXT_ECHOREPLY;
1055         else
1056                 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1057         ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1058         /* Size of iio is class_type dependent.
1059          * Only check header here and assign length based on ctype in the switch statement
1060          */
1061         iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1062         if (!ext_hdr || !iio)
1063                 goto send_mal_query;
1064         if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1065             ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1066                 goto send_mal_query;
1067         ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1068         iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1069                                  sizeof(iio->extobj_hdr) + ident_len, &_iio);
1070         if (!iio)
1071                 goto send_mal_query;
1072
1073         status = 0;
1074         dev = NULL;
1075         switch (iio->extobj_hdr.class_type) {
1076         case ICMP_EXT_ECHO_CTYPE_NAME:
1077                 if (ident_len >= IFNAMSIZ)
1078                         goto send_mal_query;
1079                 memset(buff, 0, sizeof(buff));
1080                 memcpy(buff, &iio->ident.name, ident_len);
1081                 dev = dev_get_by_name(net, buff);
1082                 break;
1083         case ICMP_EXT_ECHO_CTYPE_INDEX:
1084                 if (ident_len != sizeof(iio->ident.ifindex))
1085                         goto send_mal_query;
1086                 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1087                 break;
1088         case ICMP_EXT_ECHO_CTYPE_ADDR:
1089                 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1090                     ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1091                                  iio->ident.addr.ctype3_hdr.addrlen)
1092                         goto send_mal_query;
1093                 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1094                 case ICMP_AFI_IP:
1095                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1096                                 goto send_mal_query;
1097                         dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1098                         break;
1099 #if IS_ENABLED(CONFIG_IPV6)
1100                 case ICMP_AFI_IP6:
1101                         if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1102                                 goto send_mal_query;
1103                         dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1104                         dev_hold(dev);
1105                         break;
1106 #endif
1107                 default:
1108                         goto send_mal_query;
1109                 }
1110                 break;
1111         default:
1112                 goto send_mal_query;
1113         }
1114         if (!dev) {
1115                 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1116                 return true;
1117         }
1118         /* Fill bits in reply message */
1119         if (dev->flags & IFF_UP)
1120                 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1121
1122         in_dev = __in_dev_get_rcu(dev);
1123         if (in_dev && rcu_access_pointer(in_dev->ifa_list))
1124                 status |= ICMP_EXT_ECHOREPLY_IPV4;
1125
1126         in6_dev = __in6_dev_get(dev);
1127         if (in6_dev && !list_empty(&in6_dev->addr_list))
1128                 status |= ICMP_EXT_ECHOREPLY_IPV6;
1129
1130         dev_put(dev);
1131         icmphdr->un.echo.sequence |= htons(status);
1132         return true;
1133 send_mal_query:
1134         icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1135         return true;
1136 }
1137 EXPORT_SYMBOL_GPL(icmp_build_probe);
1138
1139 /*
1140  *      Handle ICMP Timestamp requests.
1141  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1142  *                SHOULD be in the kernel for minimum random latency.
1143  *                MUST be accurate to a few minutes.
1144  *                MUST be updated at least at 15Hz.
1145  */
1146 static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1147 {
1148         struct icmp_bxm icmp_param;
1149         /*
1150          *      Too short.
1151          */
1152         if (skb->len < 4)
1153                 goto out_err;
1154
1155         /*
1156          *      Fill in the current time as ms since midnight UT:
1157          */
1158         icmp_param.data.times[1] = inet_current_timestamp();
1159         icmp_param.data.times[2] = icmp_param.data.times[1];
1160
1161         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1162
1163         icmp_param.data.icmph      = *icmp_hdr(skb);
1164         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1165         icmp_param.data.icmph.code = 0;
1166         icmp_param.skb             = skb;
1167         icmp_param.offset          = 0;
1168         icmp_param.data_len        = 0;
1169         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1170         icmp_reply(&icmp_param, skb);
1171         return SKB_NOT_DROPPED_YET;
1172
1173 out_err:
1174         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1175         return SKB_DROP_REASON_PKT_TOO_SMALL;
1176 }
1177
1178 static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1179 {
1180         /* pretend it was a success */
1181         return SKB_NOT_DROPPED_YET;
1182 }
1183
1184 /*
1185  *      Deal with incoming ICMP packets.
1186  */
1187 int icmp_rcv(struct sk_buff *skb)
1188 {
1189         enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1190         struct rtable *rt = skb_rtable(skb);
1191         struct net *net = dev_net(rt->dst.dev);
1192         struct icmphdr *icmph;
1193
1194         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1195                 struct sec_path *sp = skb_sec_path(skb);
1196                 int nh;
1197
1198                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1199                                  XFRM_STATE_ICMP)) {
1200                         reason = SKB_DROP_REASON_XFRM_POLICY;
1201                         goto drop;
1202                 }
1203
1204                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1205                         goto drop;
1206
1207                 nh = skb_network_offset(skb);
1208                 skb_set_network_header(skb, sizeof(*icmph));
1209
1210                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1211                                                 skb)) {
1212                         reason = SKB_DROP_REASON_XFRM_POLICY;
1213                         goto drop;
1214                 }
1215
1216                 skb_set_network_header(skb, nh);
1217         }
1218
1219         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1220
1221         if (skb_checksum_simple_validate(skb))
1222                 goto csum_error;
1223
1224         if (!pskb_pull(skb, sizeof(*icmph)))
1225                 goto error;
1226
1227         icmph = icmp_hdr(skb);
1228
1229         ICMPMSGIN_INC_STATS(net, icmph->type);
1230
1231         /* Check for ICMP Extended Echo (PROBE) messages */
1232         if (icmph->type == ICMP_EXT_ECHO) {
1233                 /* We can't use icmp_pointers[].handler() because it is an array of
1234                  * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1235                  */
1236                 reason = icmp_echo(skb);
1237                 goto reason_check;
1238         }
1239
1240         if (icmph->type == ICMP_EXT_ECHOREPLY) {
1241                 reason = ping_rcv(skb);
1242                 goto reason_check;
1243         }
1244
1245         /*
1246          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1247          *
1248          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1249          *                discarded.
1250          */
1251         if (icmph->type > NR_ICMP_TYPES) {
1252                 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1253                 goto error;
1254         }
1255
1256         /*
1257          *      Parse the ICMP message
1258          */
1259
1260         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1261                 /*
1262                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1263                  *        silently ignored (we let user decide with a sysctl).
1264                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1265                  *        discarded if to broadcast/multicast.
1266                  */
1267                 if ((icmph->type == ICMP_ECHO ||
1268                      icmph->type == ICMP_TIMESTAMP) &&
1269                     READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1270                         reason = SKB_DROP_REASON_INVALID_PROTO;
1271                         goto error;
1272                 }
1273                 if (icmph->type != ICMP_ECHO &&
1274                     icmph->type != ICMP_TIMESTAMP &&
1275                     icmph->type != ICMP_ADDRESS &&
1276                     icmph->type != ICMP_ADDRESSREPLY) {
1277                         reason = SKB_DROP_REASON_INVALID_PROTO;
1278                         goto error;
1279                 }
1280         }
1281
1282         reason = icmp_pointers[icmph->type].handler(skb);
1283 reason_check:
1284         if (!reason)  {
1285                 consume_skb(skb);
1286                 return NET_RX_SUCCESS;
1287         }
1288
1289 drop:
1290         kfree_skb_reason(skb, reason);
1291         return NET_RX_DROP;
1292 csum_error:
1293         reason = SKB_DROP_REASON_ICMP_CSUM;
1294         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1295 error:
1296         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1297         goto drop;
1298 }
1299
1300 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1301 {
1302         struct icmp_extobj_hdr *objh, _objh;
1303         struct icmp_ext_hdr *exth, _exth;
1304         u16 olen;
1305
1306         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1307         if (!exth)
1308                 return false;
1309         if (exth->version != 2)
1310                 return true;
1311
1312         if (exth->checksum &&
1313             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1314                 return false;
1315
1316         off += sizeof(_exth);
1317         while (off < skb->len) {
1318                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1319                 if (!objh)
1320                         return false;
1321
1322                 olen = ntohs(objh->length);
1323                 if (olen < sizeof(_objh))
1324                         return false;
1325
1326                 off += olen;
1327                 if (off > skb->len)
1328                         return false;
1329         }
1330
1331         return true;
1332 }
1333
1334 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1335                            struct sock_ee_data_rfc4884 *out,
1336                            int thlen, int off)
1337 {
1338         int hlen;
1339
1340         /* original datagram headers: end of icmph to payload (skb->data) */
1341         hlen = -skb_transport_offset(skb) - thlen;
1342
1343         /* per rfc 4884: minimal datagram length of 128 bytes */
1344         if (off < 128 || off < hlen)
1345                 return;
1346
1347         /* kernel has stripped headers: return payload offset in bytes */
1348         off -= hlen;
1349         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1350                 return;
1351
1352         out->len = off;
1353
1354         if (!ip_icmp_error_rfc4884_validate(skb, off))
1355                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1356 }
1357 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1358
1359 int icmp_err(struct sk_buff *skb, u32 info)
1360 {
1361         struct iphdr *iph = (struct iphdr *)skb->data;
1362         int offset = iph->ihl<<2;
1363         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1364         int type = icmp_hdr(skb)->type;
1365         int code = icmp_hdr(skb)->code;
1366         struct net *net = dev_net(skb->dev);
1367
1368         /*
1369          * Use ping_err to handle all icmp errors except those
1370          * triggered by ICMP_ECHOREPLY which sent from kernel.
1371          */
1372         if (icmph->type != ICMP_ECHOREPLY) {
1373                 ping_err(skb, offset, info);
1374                 return 0;
1375         }
1376
1377         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1378                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1379         else if (type == ICMP_REDIRECT)
1380                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1381
1382         return 0;
1383 }
1384
1385 /*
1386  *      This table is the definition of how we handle ICMP.
1387  */
1388 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1389         [ICMP_ECHOREPLY] = {
1390                 .handler = ping_rcv,
1391         },
1392         [1] = {
1393                 .handler = icmp_discard,
1394                 .error = 1,
1395         },
1396         [2] = {
1397                 .handler = icmp_discard,
1398                 .error = 1,
1399         },
1400         [ICMP_DEST_UNREACH] = {
1401                 .handler = icmp_unreach,
1402                 .error = 1,
1403         },
1404         [ICMP_SOURCE_QUENCH] = {
1405                 .handler = icmp_unreach,
1406                 .error = 1,
1407         },
1408         [ICMP_REDIRECT] = {
1409                 .handler = icmp_redirect,
1410                 .error = 1,
1411         },
1412         [6] = {
1413                 .handler = icmp_discard,
1414                 .error = 1,
1415         },
1416         [7] = {
1417                 .handler = icmp_discard,
1418                 .error = 1,
1419         },
1420         [ICMP_ECHO] = {
1421                 .handler = icmp_echo,
1422         },
1423         [9] = {
1424                 .handler = icmp_discard,
1425                 .error = 1,
1426         },
1427         [10] = {
1428                 .handler = icmp_discard,
1429                 .error = 1,
1430         },
1431         [ICMP_TIME_EXCEEDED] = {
1432                 .handler = icmp_unreach,
1433                 .error = 1,
1434         },
1435         [ICMP_PARAMETERPROB] = {
1436                 .handler = icmp_unreach,
1437                 .error = 1,
1438         },
1439         [ICMP_TIMESTAMP] = {
1440                 .handler = icmp_timestamp,
1441         },
1442         [ICMP_TIMESTAMPREPLY] = {
1443                 .handler = icmp_discard,
1444         },
1445         [ICMP_INFO_REQUEST] = {
1446                 .handler = icmp_discard,
1447         },
1448         [ICMP_INFO_REPLY] = {
1449                 .handler = icmp_discard,
1450         },
1451         [ICMP_ADDRESS] = {
1452                 .handler = icmp_discard,
1453         },
1454         [ICMP_ADDRESSREPLY] = {
1455                 .handler = icmp_discard,
1456         },
1457 };
1458
1459 static int __net_init icmp_sk_init(struct net *net)
1460 {
1461         /* Control parameters for ECHO replies. */
1462         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1463         net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1464         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1465
1466         /* Control parameter - ignore bogus broadcast responses? */
1467         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1468
1469         /*
1470          *      Configurable global rate limit.
1471          *
1472          *      ratelimit defines tokens/packet consumed for dst->rate_token
1473          *      bucket ratemask defines which icmp types are ratelimited by
1474          *      setting it's bit position.
1475          *
1476          *      default:
1477          *      dest unreachable (3), source quench (4),
1478          *      time exceeded (11), parameter problem (12)
1479          */
1480
1481         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1482         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1483         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1484
1485         return 0;
1486 }
1487
1488 static struct pernet_operations __net_initdata icmp_sk_ops = {
1489        .init = icmp_sk_init,
1490 };
1491
1492 int __init icmp_init(void)
1493 {
1494         int err, i;
1495
1496         for_each_possible_cpu(i) {
1497                 struct sock *sk;
1498
1499                 err = inet_ctl_sock_create(&sk, PF_INET,
1500                                            SOCK_RAW, IPPROTO_ICMP, &init_net);
1501                 if (err < 0)
1502                         return err;
1503
1504                 per_cpu(ipv4_icmp_sk, i) = sk;
1505
1506                 /* Enough space for 2 64K ICMP packets, including
1507                  * sk_buff/skb_shared_info struct overhead.
1508                  */
1509                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1510
1511                 /*
1512                  * Speedup sock_wfree()
1513                  */
1514                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1515                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1516         }
1517         return register_pernet_subsys(&icmp_sk_ops);
1518 }