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Linux/net/ipv4/icmp.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  *      NET3:   Implementation of the ICMP protocol layer.
  4  *
  5  *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
  6  *
  7  *      Some of the function names and the icmp unreach table for this
  8  *      module were derived from [icmp.c 1.0.11 06/02/93] by
  9  *      Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
 10  *      Other than that this module is a complete rewrite.
 11  *
 12  *      Fixes:
 13  *      Clemens Fruhwirth       :       introduce global icmp rate limiting
 14  *                                      with icmp type masking ability instead
 15  *                                      of broken per type icmp timeouts.
 16  *              Mike Shaver     :       RFC1122 checks.
 17  *              Alan Cox        :       Multicast ping reply as self.
 18  *              Alan Cox        :       Fix atomicity lockup in ip_build_xmit
 19  *                                      call.
 20  *              Alan Cox        :       Added 216,128 byte paths to the MTU
 21  *                                      code.
 22  *              Martin Mares    :       RFC1812 checks.
 23  *              Martin Mares    :       Can be configured to follow redirects
 24  *                                      if acting as a router _without_ a
 25  *                                      routing protocol (RFC 1812).
 26  *              Martin Mares    :       Echo requests may be configured to
 27  *                                      be ignored (RFC 1812).
 28  *              Martin Mares    :       Limitation of ICMP error message
 29  *                                      transmit rate (RFC 1812).
 30  *              Martin Mares    :       TOS and Precedence set correctly
 31  *                                      (RFC 1812).
 32  *              Martin Mares    :       Now copying as much data from the
 33  *                                      original packet as we can without
 34  *                                      exceeding 576 bytes (RFC 1812).
 35  *      Willy Konynenberg       :       Transparent proxying support.
 36  *              Keith Owens     :       RFC1191 correction for 4.2BSD based
 37  *                                      path MTU bug.
 38  *              Thomas Quinot   :       ICMP Dest Unreach codes up to 15 are
 39  *                                      valid (RFC 1812).
 40  *              Andi Kleen      :       Check all packet lengths properly
 41  *                                      and moved all kfree_skb() up to
 42  *                                      icmp_rcv.
 43  *              Andi Kleen      :       Move the rate limit bookkeeping
 44  *                                      into the dest entry and use a token
 45  *                                      bucket filter (thanks to ANK). Make
 46  *                                      the rates sysctl configurable.
 47  *              Yu Tianli       :       Fixed two ugly bugs in icmp_send
 48  *                                      - IP option length was accounted wrongly
 49  *                                      - ICMP header length was not accounted
 50  *                                        at all.
 51  *              Tristan Greaves :       Added sysctl option to ignore bogus
 52  *                                      broadcast responses from broken routers.
 53  *
 54  * To Fix:
 55  *
 56  *      - Should use skb_pull() instead of all the manual checking.
 57  *        This would also greatly simply some upper layer error handlers. --AK
 58  */
 59 
 60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 61 
 62 #include <linux/module.h>
 63 #include <linux/types.h>
 64 #include <linux/jiffies.h>
 65 #include <linux/kernel.h>
 66 #include <linux/fcntl.h>
 67 #include <linux/socket.h>
 68 #include <linux/in.h>
 69 #include <linux/inet.h>
 70 #include <linux/inetdevice.h>
 71 #include <linux/netdevice.h>
 72 #include <linux/string.h>
 73 #include <linux/netfilter_ipv4.h>
 74 #include <linux/slab.h>
 75 #include <net/snmp.h>
 76 #include <net/ip.h>
 77 #include <net/route.h>
 78 #include <net/protocol.h>
 79 #include <net/icmp.h>
 80 #include <net/tcp.h>
 81 #include <net/udp.h>
 82 #include <net/raw.h>
 83 #include <net/ping.h>
 84 #include <linux/skbuff.h>
 85 #include <net/sock.h>
 86 #include <linux/errno.h>
 87 #include <linux/timer.h>
 88 #include <linux/init.h>
 89 #include <linux/uaccess.h>
 90 #include <net/checksum.h>
 91 #include <net/xfrm.h>
 92 #include <net/inet_common.h>
 93 #include <net/ip_fib.h>
 94 #include <net/l3mdev.h>
 95 
 96 /*
 97  *      Build xmit assembly blocks
 98  */
 99 
100 struct icmp_bxm {
101         struct sk_buff *skb;
102         int offset;
103         int data_len;
104 
105         struct {
106                 struct icmphdr icmph;
107                 __be32         times[3];
108         } data;
109         int head_len;
110         struct ip_options_data replyopts;
111 };
112 
113 /* An array of errno for error messages from dest unreach. */
114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
115 
116 const struct icmp_err icmp_err_convert[] = {
117         {
118                 .errno = ENETUNREACH,   /* ICMP_NET_UNREACH */
119                 .fatal = 0,
120         },
121         {
122                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNREACH */
123                 .fatal = 0,
124         },
125         {
126                 .errno = ENOPROTOOPT    /* ICMP_PROT_UNREACH */,
127                 .fatal = 1,
128         },
129         {
130                 .errno = ECONNREFUSED,  /* ICMP_PORT_UNREACH */
131                 .fatal = 1,
132         },
133         {
134                 .errno = EMSGSIZE,      /* ICMP_FRAG_NEEDED */
135                 .fatal = 0,
136         },
137         {
138                 .errno = EOPNOTSUPP,    /* ICMP_SR_FAILED */
139                 .fatal = 0,
140         },
141         {
142                 .errno = ENETUNREACH,   /* ICMP_NET_UNKNOWN */
143                 .fatal = 1,
144         },
145         {
146                 .errno = EHOSTDOWN,     /* ICMP_HOST_UNKNOWN */
147                 .fatal = 1,
148         },
149         {
150                 .errno = ENONET,        /* ICMP_HOST_ISOLATED */
151                 .fatal = 1,
152         },
153         {
154                 .errno = ENETUNREACH,   /* ICMP_NET_ANO */
155                 .fatal = 1,
156         },
157         {
158                 .errno = EHOSTUNREACH,  /* ICMP_HOST_ANO */
159                 .fatal = 1,
160         },
161         {
162                 .errno = ENETUNREACH,   /* ICMP_NET_UNR_TOS */
163                 .fatal = 0,
164         },
165         {
166                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNR_TOS */
167                 .fatal = 0,
168         },
169         {
170                 .errno = EHOSTUNREACH,  /* ICMP_PKT_FILTERED */
171                 .fatal = 1,
172         },
173         {
174                 .errno = EHOSTUNREACH,  /* ICMP_PREC_VIOLATION */
175                 .fatal = 1,
176         },
177         {
178                 .errno = EHOSTUNREACH,  /* ICMP_PREC_CUTOFF */
179                 .fatal = 1,
180         },
181 };
182 EXPORT_SYMBOL(icmp_err_convert);
183 
184 /*
185  *      ICMP control array. This specifies what to do with each ICMP.
186  */
187 
188 struct icmp_control {
189         bool (*handler)(struct sk_buff *skb);
190         short   error;          /* This ICMP is classed as an error message */
191 };
192 
193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
194 
195 /*
196  *      The ICMP socket(s). This is the most convenient way to flow control
197  *      our ICMP output as well as maintain a clean interface throughout
198  *      all layers. All Socketless IP sends will soon be gone.
199  *
200  *      On SMP we have one ICMP socket per-cpu.
201  */
202 static struct sock *icmp_sk(struct net *net)
203 {
204         return this_cpu_read(*net->ipv4.icmp_sk);
205 }
206 
207 /* Called with BH disabled */
208 static inline struct sock *icmp_xmit_lock(struct net *net)
209 {
210         struct sock *sk;
211 
212         sk = icmp_sk(net);
213 
214         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
215                 /* This can happen if the output path signals a
216                  * dst_link_failure() for an outgoing ICMP packet.
217                  */
218                 return NULL;
219         }
220         return sk;
221 }
222 
223 static inline void icmp_xmit_unlock(struct sock *sk)
224 {
225         spin_unlock(&sk->sk_lock.slock);
226 }
227 
228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
229 int sysctl_icmp_msgs_burst __read_mostly = 50;
230 
231 static struct {
232         spinlock_t      lock;
233         u32             credit;
234         u32             stamp;
235 } icmp_global = {
236         .lock           = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
237 };
238 
239 /**
240  * icmp_global_allow - Are we allowed to send one more ICMP message ?
241  *
242  * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
243  * Returns false if we reached the limit and can not send another packet.
244  * Note: called with BH disabled
245  */
246 bool icmp_global_allow(void)
247 {
248         u32 credit, delta, incr = 0, now = (u32)jiffies;
249         bool rc = false;
250 
251         /* Check if token bucket is empty and cannot be refilled
252          * without taking the spinlock. The READ_ONCE() are paired
253          * with the following WRITE_ONCE() in this same function.
254          */
255         if (!READ_ONCE(icmp_global.credit)) {
256                 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
257                 if (delta < HZ / 50)
258                         return false;
259         }
260 
261         spin_lock(&icmp_global.lock);
262         delta = min_t(u32, now - icmp_global.stamp, HZ);
263         if (delta >= HZ / 50) {
264                 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
265                 if (incr)
266                         WRITE_ONCE(icmp_global.stamp, now);
267         }
268         credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
269         if (credit) {
270                 /* We want to use a credit of one in average, but need to randomize
271                  * it for security reasons.
272                  */
273                 credit = max_t(int, credit - prandom_u32_max(3), 0);
274                 rc = true;
275         }
276         WRITE_ONCE(icmp_global.credit, credit);
277         spin_unlock(&icmp_global.lock);
278         return rc;
279 }
280 EXPORT_SYMBOL(icmp_global_allow);
281 
282 static bool icmpv4_mask_allow(struct net *net, int type, int code)
283 {
284         if (type > NR_ICMP_TYPES)
285                 return true;
286 
287         /* Don't limit PMTU discovery. */
288         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
289                 return true;
290 
291         /* Limit if icmp type is enabled in ratemask. */
292         if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
293                 return true;
294 
295         return false;
296 }
297 
298 static bool icmpv4_global_allow(struct net *net, int type, int code)
299 {
300         if (icmpv4_mask_allow(net, type, code))
301                 return true;
302 
303         if (icmp_global_allow())
304                 return true;
305 
306         return false;
307 }
308 
309 /*
310  *      Send an ICMP frame.
311  */
312 
313 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
314                                struct flowi4 *fl4, int type, int code)
315 {
316         struct dst_entry *dst = &rt->dst;
317         struct inet_peer *peer;
318         bool rc = true;
319         int vif;
320 
321         if (icmpv4_mask_allow(net, type, code))
322                 goto out;
323 
324         /* No rate limit on loopback */
325         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
326                 goto out;
327 
328         vif = l3mdev_master_ifindex(dst->dev);
329         peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
330         rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
331         if (peer)
332                 inet_putpeer(peer);
333 out:
334         return rc;
335 }
336 
337 /*
338  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
339  */
340 void icmp_out_count(struct net *net, unsigned char type)
341 {
342         ICMPMSGOUT_INC_STATS(net, type);
343         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
344 }
345 
346 /*
347  *      Checksum each fragment, and on the first include the headers and final
348  *      checksum.
349  */
350 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
351                           struct sk_buff *skb)
352 {
353         struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
354         __wsum csum;
355 
356         csum = skb_copy_and_csum_bits(icmp_param->skb,
357                                       icmp_param->offset + offset,
358                                       to, len);
359 
360         skb->csum = csum_block_add(skb->csum, csum, odd);
361         if (icmp_pointers[icmp_param->data.icmph.type].error)
362                 nf_ct_attach(skb, icmp_param->skb);
363         return 0;
364 }
365 
366 static void icmp_push_reply(struct icmp_bxm *icmp_param,
367                             struct flowi4 *fl4,
368                             struct ipcm_cookie *ipc, struct rtable **rt)
369 {
370         struct sock *sk;
371         struct sk_buff *skb;
372 
373         sk = icmp_sk(dev_net((*rt)->dst.dev));
374         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
375                            icmp_param->data_len+icmp_param->head_len,
376                            icmp_param->head_len,
377                            ipc, rt, MSG_DONTWAIT) < 0) {
378                 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
379                 ip_flush_pending_frames(sk);
380         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
381                 struct icmphdr *icmph = icmp_hdr(skb);
382                 __wsum csum;
383                 struct sk_buff *skb1;
384 
385                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
386                                                  (char *)icmph,
387                                                  icmp_param->head_len);
388                 skb_queue_walk(&sk->sk_write_queue, skb1) {
389                         csum = csum_add(csum, skb1->csum);
390                 }
391                 icmph->checksum = csum_fold(csum);
392                 skb->ip_summed = CHECKSUM_NONE;
393                 ip_push_pending_frames(sk, fl4);
394         }
395 }
396 
397 /*
398  *      Driving logic for building and sending ICMP messages.
399  */
400 
401 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
402 {
403         struct ipcm_cookie ipc;
404         struct rtable *rt = skb_rtable(skb);
405         struct net *net = dev_net(rt->dst.dev);
406         struct flowi4 fl4;
407         struct sock *sk;
408         struct inet_sock *inet;
409         __be32 daddr, saddr;
410         u32 mark = IP4_REPLY_MARK(net, skb->mark);
411         int type = icmp_param->data.icmph.type;
412         int code = icmp_param->data.icmph.code;
413 
414         if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
415                 return;
416 
417         /* Needed by both icmp_global_allow and icmp_xmit_lock */
418         local_bh_disable();
419 
420         /* global icmp_msgs_per_sec */
421         if (!icmpv4_global_allow(net, type, code))
422                 goto out_bh_enable;
423 
424         sk = icmp_xmit_lock(net);
425         if (!sk)
426                 goto out_bh_enable;
427         inet = inet_sk(sk);
428 
429         icmp_param->data.icmph.checksum = 0;
430 
431         ipcm_init(&ipc);
432         inet->tos = ip_hdr(skb)->tos;
433         ipc.sockc.mark = mark;
434         daddr = ipc.addr = ip_hdr(skb)->saddr;
435         saddr = fib_compute_spec_dst(skb);
436 
437         if (icmp_param->replyopts.opt.opt.optlen) {
438                 ipc.opt = &icmp_param->replyopts.opt;
439                 if (ipc.opt->opt.srr)
440                         daddr = icmp_param->replyopts.opt.opt.faddr;
441         }
442         memset(&fl4, 0, sizeof(fl4));
443         fl4.daddr = daddr;
444         fl4.saddr = saddr;
445         fl4.flowi4_mark = mark;
446         fl4.flowi4_uid = sock_net_uid(net, NULL);
447         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
448         fl4.flowi4_proto = IPPROTO_ICMP;
449         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
450         security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
451         rt = ip_route_output_key(net, &fl4);
452         if (IS_ERR(rt))
453                 goto out_unlock;
454         if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
455                 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
456         ip_rt_put(rt);
457 out_unlock:
458         icmp_xmit_unlock(sk);
459 out_bh_enable:
460         local_bh_enable();
461 }
462 
463 /*
464  * The device used for looking up which routing table to use for sending an ICMP
465  * error is preferably the source whenever it is set, which should ensure the
466  * icmp error can be sent to the source host, else lookup using the routing
467  * table of the destination device, else use the main routing table (index 0).
468  */
469 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
470 {
471         struct net_device *route_lookup_dev = NULL;
472 
473         if (skb->dev)
474                 route_lookup_dev = skb->dev;
475         else if (skb_dst(skb))
476                 route_lookup_dev = skb_dst(skb)->dev;
477         return route_lookup_dev;
478 }
479 
480 static struct rtable *icmp_route_lookup(struct net *net,
481                                         struct flowi4 *fl4,
482                                         struct sk_buff *skb_in,
483                                         const struct iphdr *iph,
484                                         __be32 saddr, u8 tos, u32 mark,
485                                         int type, int code,
486                                         struct icmp_bxm *param)
487 {
488         struct net_device *route_lookup_dev;
489         struct rtable *rt, *rt2;
490         struct flowi4 fl4_dec;
491         int err;
492 
493         memset(fl4, 0, sizeof(*fl4));
494         fl4->daddr = (param->replyopts.opt.opt.srr ?
495                       param->replyopts.opt.opt.faddr : iph->saddr);
496         fl4->saddr = saddr;
497         fl4->flowi4_mark = mark;
498         fl4->flowi4_uid = sock_net_uid(net, NULL);
499         fl4->flowi4_tos = RT_TOS(tos);
500         fl4->flowi4_proto = IPPROTO_ICMP;
501         fl4->fl4_icmp_type = type;
502         fl4->fl4_icmp_code = code;
503         route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
504         fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
505 
506         security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
507         rt = ip_route_output_key_hash(net, fl4, skb_in);
508         if (IS_ERR(rt))
509                 return rt;
510 
511         /* No need to clone since we're just using its address. */
512         rt2 = rt;
513 
514         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
515                                            flowi4_to_flowi(fl4), NULL, 0);
516         if (!IS_ERR(rt)) {
517                 if (rt != rt2)
518                         return rt;
519         } else if (PTR_ERR(rt) == -EPERM) {
520                 rt = NULL;
521         } else
522                 return rt;
523 
524         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
525         if (err)
526                 goto relookup_failed;
527 
528         if (inet_addr_type_dev_table(net, route_lookup_dev,
529                                      fl4_dec.saddr) == RTN_LOCAL) {
530                 rt2 = __ip_route_output_key(net, &fl4_dec);
531                 if (IS_ERR(rt2))
532                         err = PTR_ERR(rt2);
533         } else {
534                 struct flowi4 fl4_2 = {};
535                 unsigned long orefdst;
536 
537                 fl4_2.daddr = fl4_dec.saddr;
538                 rt2 = ip_route_output_key(net, &fl4_2);
539                 if (IS_ERR(rt2)) {
540                         err = PTR_ERR(rt2);
541                         goto relookup_failed;
542                 }
543                 /* Ugh! */
544                 orefdst = skb_in->_skb_refdst; /* save old refdst */
545                 skb_dst_set(skb_in, NULL);
546                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
547                                      RT_TOS(tos), rt2->dst.dev);
548 
549                 dst_release(&rt2->dst);
550                 rt2 = skb_rtable(skb_in);
551                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
552         }
553 
554         if (err)
555                 goto relookup_failed;
556 
557         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
558                                             flowi4_to_flowi(&fl4_dec), NULL,
559                                             XFRM_LOOKUP_ICMP);
560         if (!IS_ERR(rt2)) {
561                 dst_release(&rt->dst);
562                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
563                 rt = rt2;
564         } else if (PTR_ERR(rt2) == -EPERM) {
565                 if (rt)
566                         dst_release(&rt->dst);
567                 return rt2;
568         } else {
569                 err = PTR_ERR(rt2);
570                 goto relookup_failed;
571         }
572         return rt;
573 
574 relookup_failed:
575         if (rt)
576                 return rt;
577         return ERR_PTR(err);
578 }
579 
580 /*
581  *      Send an ICMP message in response to a situation
582  *
583  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
584  *                MAY send more (we do).
585  *                      MUST NOT change this header information.
586  *                      MUST NOT reply to a multicast/broadcast IP address.
587  *                      MUST NOT reply to a multicast/broadcast MAC address.
588  *                      MUST reply to only the first fragment.
589  */
590 
591 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
592                  const struct ip_options *opt)
593 {
594         struct iphdr *iph;
595         int room;
596         struct icmp_bxm icmp_param;
597         struct rtable *rt = skb_rtable(skb_in);
598         struct ipcm_cookie ipc;
599         struct flowi4 fl4;
600         __be32 saddr;
601         u8  tos;
602         u32 mark;
603         struct net *net;
604         struct sock *sk;
605 
606         if (!rt)
607                 goto out;
608 
609         if (rt->dst.dev)
610                 net = dev_net(rt->dst.dev);
611         else if (skb_in->dev)
612                 net = dev_net(skb_in->dev);
613         else
614                 goto out;
615 
616         /*
617          *      Find the original header. It is expected to be valid, of course.
618          *      Check this, icmp_send is called from the most obscure devices
619          *      sometimes.
620          */
621         iph = ip_hdr(skb_in);
622 
623         if ((u8 *)iph < skb_in->head ||
624             (skb_network_header(skb_in) + sizeof(*iph)) >
625             skb_tail_pointer(skb_in))
626                 goto out;
627 
628         /*
629          *      No replies to physical multicast/broadcast
630          */
631         if (skb_in->pkt_type != PACKET_HOST)
632                 goto out;
633 
634         /*
635          *      Now check at the protocol level
636          */
637         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
638                 goto out;
639 
640         /*
641          *      Only reply to fragment 0. We byte re-order the constant
642          *      mask for efficiency.
643          */
644         if (iph->frag_off & htons(IP_OFFSET))
645                 goto out;
646 
647         /*
648          *      If we send an ICMP error to an ICMP error a mess would result..
649          */
650         if (icmp_pointers[type].error) {
651                 /*
652                  *      We are an error, check if we are replying to an
653                  *      ICMP error
654                  */
655                 if (iph->protocol == IPPROTO_ICMP) {
656                         u8 _inner_type, *itp;
657 
658                         itp = skb_header_pointer(skb_in,
659                                                  skb_network_header(skb_in) +
660                                                  (iph->ihl << 2) +
661                                                  offsetof(struct icmphdr,
662                                                           type) -
663                                                  skb_in->data,
664                                                  sizeof(_inner_type),
665                                                  &_inner_type);
666                         if (!itp)
667                                 goto out;
668 
669                         /*
670                          *      Assume any unknown ICMP type is an error. This
671                          *      isn't specified by the RFC, but think about it..
672                          */
673                         if (*itp > NR_ICMP_TYPES ||
674                             icmp_pointers[*itp].error)
675                                 goto out;
676                 }
677         }
678 
679         /* Needed by both icmp_global_allow and icmp_xmit_lock */
680         local_bh_disable();
681 
682         /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
683          * incoming dev is loopback.  If outgoing dev change to not be
684          * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
685          */
686         if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
687               !icmpv4_global_allow(net, type, code))
688                 goto out_bh_enable;
689 
690         sk = icmp_xmit_lock(net);
691         if (!sk)
692                 goto out_bh_enable;
693 
694         /*
695          *      Construct source address and options.
696          */
697 
698         saddr = iph->daddr;
699         if (!(rt->rt_flags & RTCF_LOCAL)) {
700                 struct net_device *dev = NULL;
701 
702                 rcu_read_lock();
703                 if (rt_is_input_route(rt) &&
704                     net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
705                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
706 
707                 if (dev)
708                         saddr = inet_select_addr(dev, iph->saddr,
709                                                  RT_SCOPE_LINK);
710                 else
711                         saddr = 0;
712                 rcu_read_unlock();
713         }
714 
715         tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
716                                            IPTOS_PREC_INTERNETCONTROL) :
717                                            iph->tos;
718         mark = IP4_REPLY_MARK(net, skb_in->mark);
719 
720         if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
721                 goto out_unlock;
722 
723 
724         /*
725          *      Prepare data for ICMP header.
726          */
727 
728         icmp_param.data.icmph.type       = type;
729         icmp_param.data.icmph.code       = code;
730         icmp_param.data.icmph.un.gateway = info;
731         icmp_param.data.icmph.checksum   = 0;
732         icmp_param.skb    = skb_in;
733         icmp_param.offset = skb_network_offset(skb_in);
734         inet_sk(sk)->tos = tos;
735         ipcm_init(&ipc);
736         ipc.addr = iph->saddr;
737         ipc.opt = &icmp_param.replyopts.opt;
738         ipc.sockc.mark = mark;
739 
740         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
741                                type, code, &icmp_param);
742         if (IS_ERR(rt))
743                 goto out_unlock;
744 
745         /* peer icmp_ratelimit */
746         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
747                 goto ende;
748 
749         /* RFC says return as much as we can without exceeding 576 bytes. */
750 
751         room = dst_mtu(&rt->dst);
752         if (room > 576)
753                 room = 576;
754         room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
755         room -= sizeof(struct icmphdr);
756 
757         icmp_param.data_len = skb_in->len - icmp_param.offset;
758         if (icmp_param.data_len > room)
759                 icmp_param.data_len = room;
760         icmp_param.head_len = sizeof(struct icmphdr);
761 
762         /* if we don't have a source address at this point, fall back to the
763          * dummy address instead of sending out a packet with a source address
764          * of 0.0.0.0
765          */
766         if (!fl4.saddr)
767                 fl4.saddr = htonl(INADDR_DUMMY);
768 
769         icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
770 ende:
771         ip_rt_put(rt);
772 out_unlock:
773         icmp_xmit_unlock(sk);
774 out_bh_enable:
775         local_bh_enable();
776 out:;
777 }
778 EXPORT_SYMBOL(__icmp_send);
779 
780 #if IS_ENABLED(CONFIG_NF_NAT)
781 #include <net/netfilter/nf_conntrack.h>
782 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
783 {
784         struct sk_buff *cloned_skb = NULL;
785         struct ip_options opts = { 0 };
786         enum ip_conntrack_info ctinfo;
787         struct nf_conn *ct;
788         __be32 orig_ip;
789 
790         ct = nf_ct_get(skb_in, &ctinfo);
791         if (!ct || !(ct->status & IPS_SRC_NAT)) {
792                 __icmp_send(skb_in, type, code, info, &opts);
793                 return;
794         }
795 
796         if (skb_shared(skb_in))
797                 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
798 
799         if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
800             (skb_network_header(skb_in) + sizeof(struct iphdr)) >
801             skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
802             skb_network_offset(skb_in) + sizeof(struct iphdr))))
803                 goto out;
804 
805         orig_ip = ip_hdr(skb_in)->saddr;
806         ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
807         __icmp_send(skb_in, type, code, info, &opts);
808         ip_hdr(skb_in)->saddr = orig_ip;
809 out:
810         consume_skb(cloned_skb);
811 }
812 EXPORT_SYMBOL(icmp_ndo_send);
813 #endif
814 
815 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
816 {
817         const struct iphdr *iph = (const struct iphdr *)skb->data;
818         const struct net_protocol *ipprot;
819         int protocol = iph->protocol;
820 
821         /* Checkin full IP header plus 8 bytes of protocol to
822          * avoid additional coding at protocol handlers.
823          */
824         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
825                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
826                 return;
827         }
828 
829         raw_icmp_error(skb, protocol, info);
830 
831         ipprot = rcu_dereference(inet_protos[protocol]);
832         if (ipprot && ipprot->err_handler)
833                 ipprot->err_handler(skb, info);
834 }
835 
836 static bool icmp_tag_validation(int proto)
837 {
838         bool ok;
839 
840         rcu_read_lock();
841         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
842         rcu_read_unlock();
843         return ok;
844 }
845 
846 /*
847  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
848  *      ICMP_PARAMETERPROB.
849  */
850 
851 static bool icmp_unreach(struct sk_buff *skb)
852 {
853         const struct iphdr *iph;
854         struct icmphdr *icmph;
855         struct net *net;
856         u32 info = 0;
857 
858         net = dev_net(skb_dst(skb)->dev);
859 
860         /*
861          *      Incomplete header ?
862          *      Only checks for the IP header, there should be an
863          *      additional check for longer headers in upper levels.
864          */
865 
866         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
867                 goto out_err;
868 
869         icmph = icmp_hdr(skb);
870         iph   = (const struct iphdr *)skb->data;
871 
872         if (iph->ihl < 5) /* Mangled header, drop. */
873                 goto out_err;
874 
875         switch (icmph->type) {
876         case ICMP_DEST_UNREACH:
877                 switch (icmph->code & 15) {
878                 case ICMP_NET_UNREACH:
879                 case ICMP_HOST_UNREACH:
880                 case ICMP_PROT_UNREACH:
881                 case ICMP_PORT_UNREACH:
882                         break;
883                 case ICMP_FRAG_NEEDED:
884                         /* for documentation of the ip_no_pmtu_disc
885                          * values please see
886                          * Documentation/networking/ip-sysctl.rst
887                          */
888                         switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
889                         default:
890                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
891                                                     &iph->daddr);
892                                 break;
893                         case 2:
894                                 goto out;
895                         case 3:
896                                 if (!icmp_tag_validation(iph->protocol))
897                                         goto out;
898                                 fallthrough;
899                         case 0:
900                                 info = ntohs(icmph->un.frag.mtu);
901                         }
902                         break;
903                 case ICMP_SR_FAILED:
904                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
905                                             &iph->daddr);
906                         break;
907                 default:
908                         break;
909                 }
910                 if (icmph->code > NR_ICMP_UNREACH)
911                         goto out;
912                 break;
913         case ICMP_PARAMETERPROB:
914                 info = ntohl(icmph->un.gateway) >> 24;
915                 break;
916         case ICMP_TIME_EXCEEDED:
917                 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
918                 if (icmph->code == ICMP_EXC_FRAGTIME)
919                         goto out;
920                 break;
921         }
922 
923         /*
924          *      Throw it at our lower layers
925          *
926          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
927          *                header.
928          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
929          *                transport layer.
930          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
931          *                transport layer.
932          */
933 
934         /*
935          *      Check the other end isn't violating RFC 1122. Some routers send
936          *      bogus responses to broadcast frames. If you see this message
937          *      first check your netmask matches at both ends, if it does then
938          *      get the other vendor to fix their kit.
939          */
940 
941         if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
942             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
943                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
944                                      &ip_hdr(skb)->saddr,
945                                      icmph->type, icmph->code,
946                                      &iph->daddr, skb->dev->name);
947                 goto out;
948         }
949 
950         icmp_socket_deliver(skb, info);
951 
952 out:
953         return true;
954 out_err:
955         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
956         return false;
957 }
958 
959 
960 /*
961  *      Handle ICMP_REDIRECT.
962  */
963 
964 static bool icmp_redirect(struct sk_buff *skb)
965 {
966         if (skb->len < sizeof(struct iphdr)) {
967                 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
968                 return false;
969         }
970 
971         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
972                 /* there aught to be a stat */
973                 return false;
974         }
975 
976         icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
977         return true;
978 }
979 
980 /*
981  *      Handle ICMP_ECHO ("ping") requests.
982  *
983  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
984  *                requests.
985  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
986  *                included in the reply.
987  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
988  *                echo requests, MUST have default=NOT.
989  *      See also WRT handling of options once they are done and working.
990  */
991 
992 static bool icmp_echo(struct sk_buff *skb)
993 {
994         struct net *net;
995 
996         net = dev_net(skb_dst(skb)->dev);
997         if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
998                 struct icmp_bxm icmp_param;
999 
1000                 icmp_param.data.icmph      = *icmp_hdr(skb);
1001                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1002                 icmp_param.skb             = skb;
1003                 icmp_param.offset          = 0;
1004                 icmp_param.data_len        = skb->len;
1005                 icmp_param.head_len        = sizeof(struct icmphdr);
1006                 icmp_reply(&icmp_param, skb);
1007         }
1008         /* should there be an ICMP stat for ignored echos? */
1009         return true;
1010 }
1011 
1012 /*
1013  *      Handle ICMP Timestamp requests.
1014  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1015  *                SHOULD be in the kernel for minimum random latency.
1016  *                MUST be accurate to a few minutes.
1017  *                MUST be updated at least at 15Hz.
1018  */
1019 static bool icmp_timestamp(struct sk_buff *skb)
1020 {
1021         struct icmp_bxm icmp_param;
1022         /*
1023          *      Too short.
1024          */
1025         if (skb->len < 4)
1026                 goto out_err;
1027 
1028         /*
1029          *      Fill in the current time as ms since midnight UT:
1030          */
1031         icmp_param.data.times[1] = inet_current_timestamp();
1032         icmp_param.data.times[2] = icmp_param.data.times[1];
1033 
1034         BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1035 
1036         icmp_param.data.icmph      = *icmp_hdr(skb);
1037         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1038         icmp_param.data.icmph.code = 0;
1039         icmp_param.skb             = skb;
1040         icmp_param.offset          = 0;
1041         icmp_param.data_len        = 0;
1042         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
1043         icmp_reply(&icmp_param, skb);
1044         return true;
1045 
1046 out_err:
1047         __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1048         return false;
1049 }
1050 
1051 static bool icmp_discard(struct sk_buff *skb)
1052 {
1053         /* pretend it was a success */
1054         return true;
1055 }
1056 
1057 /*
1058  *      Deal with incoming ICMP packets.
1059  */
1060 int icmp_rcv(struct sk_buff *skb)
1061 {
1062         struct icmphdr *icmph;
1063         struct rtable *rt = skb_rtable(skb);
1064         struct net *net = dev_net(rt->dst.dev);
1065         bool success;
1066 
1067         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1068                 struct sec_path *sp = skb_sec_path(skb);
1069                 int nh;
1070 
1071                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1072                                  XFRM_STATE_ICMP))
1073                         goto drop;
1074 
1075                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1076                         goto drop;
1077 
1078                 nh = skb_network_offset(skb);
1079                 skb_set_network_header(skb, sizeof(*icmph));
1080 
1081                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1082                         goto drop;
1083 
1084                 skb_set_network_header(skb, nh);
1085         }
1086 
1087         __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1088 
1089         if (skb_checksum_simple_validate(skb))
1090                 goto csum_error;
1091 
1092         if (!pskb_pull(skb, sizeof(*icmph)))
1093                 goto error;
1094 
1095         icmph = icmp_hdr(skb);
1096 
1097         ICMPMSGIN_INC_STATS(net, icmph->type);
1098         /*
1099          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1100          *
1101          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1102          *                discarded.
1103          */
1104         if (icmph->type > NR_ICMP_TYPES)
1105                 goto error;
1106 
1107 
1108         /*
1109          *      Parse the ICMP message
1110          */
1111 
1112         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1113                 /*
1114                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1115                  *        silently ignored (we let user decide with a sysctl).
1116                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1117                  *        discarded if to broadcast/multicast.
1118                  */
1119                 if ((icmph->type == ICMP_ECHO ||
1120                      icmph->type == ICMP_TIMESTAMP) &&
1121                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1122                         goto error;
1123                 }
1124                 if (icmph->type != ICMP_ECHO &&
1125                     icmph->type != ICMP_TIMESTAMP &&
1126                     icmph->type != ICMP_ADDRESS &&
1127                     icmph->type != ICMP_ADDRESSREPLY) {
1128                         goto error;
1129                 }
1130         }
1131 
1132         success = icmp_pointers[icmph->type].handler(skb);
1133 
1134         if (success)  {
1135                 consume_skb(skb);
1136                 return NET_RX_SUCCESS;
1137         }
1138 
1139 drop:
1140         kfree_skb(skb);
1141         return NET_RX_DROP;
1142 csum_error:
1143         __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1144 error:
1145         __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1146         goto drop;
1147 }
1148 
1149 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1150 {
1151         struct icmp_extobj_hdr *objh, _objh;
1152         struct icmp_ext_hdr *exth, _exth;
1153         u16 olen;
1154 
1155         exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1156         if (!exth)
1157                 return false;
1158         if (exth->version != 2)
1159                 return true;
1160 
1161         if (exth->checksum &&
1162             csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1163                 return false;
1164 
1165         off += sizeof(_exth);
1166         while (off < skb->len) {
1167                 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1168                 if (!objh)
1169                         return false;
1170 
1171                 olen = ntohs(objh->length);
1172                 if (olen < sizeof(_objh))
1173                         return false;
1174 
1175                 off += olen;
1176                 if (off > skb->len)
1177                         return false;
1178         }
1179 
1180         return true;
1181 }
1182 
1183 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1184                            struct sock_ee_data_rfc4884 *out,
1185                            int thlen, int off)
1186 {
1187         int hlen;
1188 
1189         /* original datagram headers: end of icmph to payload (skb->data) */
1190         hlen = -skb_transport_offset(skb) - thlen;
1191 
1192         /* per rfc 4884: minimal datagram length of 128 bytes */
1193         if (off < 128 || off < hlen)
1194                 return;
1195 
1196         /* kernel has stripped headers: return payload offset in bytes */
1197         off -= hlen;
1198         if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1199                 return;
1200 
1201         out->len = off;
1202 
1203         if (!ip_icmp_error_rfc4884_validate(skb, off))
1204                 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1205 }
1206 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1207 
1208 int icmp_err(struct sk_buff *skb, u32 info)
1209 {
1210         struct iphdr *iph = (struct iphdr *)skb->data;
1211         int offset = iph->ihl<<2;
1212         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1213         int type = icmp_hdr(skb)->type;
1214         int code = icmp_hdr(skb)->code;
1215         struct net *net = dev_net(skb->dev);
1216 
1217         /*
1218          * Use ping_err to handle all icmp errors except those
1219          * triggered by ICMP_ECHOREPLY which sent from kernel.
1220          */
1221         if (icmph->type != ICMP_ECHOREPLY) {
1222                 ping_err(skb, offset, info);
1223                 return 0;
1224         }
1225 
1226         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1227                 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1228         else if (type == ICMP_REDIRECT)
1229                 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1230 
1231         return 0;
1232 }
1233 
1234 /*
1235  *      This table is the definition of how we handle ICMP.
1236  */
1237 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1238         [ICMP_ECHOREPLY] = {
1239                 .handler = ping_rcv,
1240         },
1241         [1] = {
1242                 .handler = icmp_discard,
1243                 .error = 1,
1244         },
1245         [2] = {
1246                 .handler = icmp_discard,
1247                 .error = 1,
1248         },
1249         [ICMP_DEST_UNREACH] = {
1250                 .handler = icmp_unreach,
1251                 .error = 1,
1252         },
1253         [ICMP_SOURCE_QUENCH] = {
1254                 .handler = icmp_unreach,
1255                 .error = 1,
1256         },
1257         [ICMP_REDIRECT] = {
1258                 .handler = icmp_redirect,
1259                 .error = 1,
1260         },
1261         [6] = {
1262                 .handler = icmp_discard,
1263                 .error = 1,
1264         },
1265         [7] = {
1266                 .handler = icmp_discard,
1267                 .error = 1,
1268         },
1269         [ICMP_ECHO] = {
1270                 .handler = icmp_echo,
1271         },
1272         [9] = {
1273                 .handler = icmp_discard,
1274                 .error = 1,
1275         },
1276         [10] = {
1277                 .handler = icmp_discard,
1278                 .error = 1,
1279         },
1280         [ICMP_TIME_EXCEEDED] = {
1281                 .handler = icmp_unreach,
1282                 .error = 1,
1283         },
1284         [ICMP_PARAMETERPROB] = {
1285                 .handler = icmp_unreach,
1286                 .error = 1,
1287         },
1288         [ICMP_TIMESTAMP] = {
1289                 .handler = icmp_timestamp,
1290         },
1291         [ICMP_TIMESTAMPREPLY] = {
1292                 .handler = icmp_discard,
1293         },
1294         [ICMP_INFO_REQUEST] = {
1295                 .handler = icmp_discard,
1296         },
1297         [ICMP_INFO_REPLY] = {
1298                 .handler = icmp_discard,
1299         },
1300         [ICMP_ADDRESS] = {
1301                 .handler = icmp_discard,
1302         },
1303         [ICMP_ADDRESSREPLY] = {
1304                 .handler = icmp_discard,
1305         },
1306 };
1307 
1308 static void __net_exit icmp_sk_exit(struct net *net)
1309 {
1310         int i;
1311 
1312         for_each_possible_cpu(i)
1313                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1314         free_percpu(net->ipv4.icmp_sk);
1315         net->ipv4.icmp_sk = NULL;
1316 }
1317 
1318 static int __net_init icmp_sk_init(struct net *net)
1319 {
1320         int i, err;
1321 
1322         net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1323         if (!net->ipv4.icmp_sk)
1324                 return -ENOMEM;
1325 
1326         for_each_possible_cpu(i) {
1327                 struct sock *sk;
1328 
1329                 err = inet_ctl_sock_create(&sk, PF_INET,
1330                                            SOCK_RAW, IPPROTO_ICMP, net);
1331                 if (err < 0)
1332                         goto fail;
1333 
1334                 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1335 
1336                 /* Enough space for 2 64K ICMP packets, including
1337                  * sk_buff/skb_shared_info struct overhead.
1338                  */
1339                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1340 
1341                 /*
1342                  * Speedup sock_wfree()
1343                  */
1344                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1345                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1346         }
1347 
1348         /* Control parameters for ECHO replies. */
1349         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1350         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1351 
1352         /* Control parameter - ignore bogus broadcast responses? */
1353         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1354 
1355         /*
1356          *      Configurable global rate limit.
1357          *
1358          *      ratelimit defines tokens/packet consumed for dst->rate_token
1359          *      bucket ratemask defines which icmp types are ratelimited by
1360          *      setting it's bit position.
1361          *
1362          *      default:
1363          *      dest unreachable (3), source quench (4),
1364          *      time exceeded (11), parameter problem (12)
1365          */
1366 
1367         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1368         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1369         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1370 
1371         return 0;
1372 
1373 fail:
1374         icmp_sk_exit(net);
1375         return err;
1376 }
1377 
1378 static struct pernet_operations __net_initdata icmp_sk_ops = {
1379        .init = icmp_sk_init,
1380        .exit = icmp_sk_exit,
1381 };
1382 
1383 int __init icmp_init(void)
1384 {
1385         return register_pernet_subsys(&icmp_sk_ops);
1386 }
1387 

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