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Linux/net/ipv4/icmp.c

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  1 /*
  2  *      NET3:   Implementation of the ICMP protocol layer.
  3  *
  4  *              Alan Cox, <alan@lxorguk.ukuu.org.uk>
  5  *
  6  *      This program is free software; you can redistribute it and/or
  7  *      modify it under the terms of the GNU General Public License
  8  *      as published by the Free Software Foundation; either version
  9  *      2 of the License, or (at your option) any later version.
 10  *
 11  *      Some of the function names and the icmp unreach table for this
 12  *      module were derived from [icmp.c 1.0.11 06/02/93] by
 13  *      Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
 14  *      Other than that this module is a complete rewrite.
 15  *
 16  *      Fixes:
 17  *      Clemens Fruhwirth       :       introduce global icmp rate limiting
 18  *                                      with icmp type masking ability instead
 19  *                                      of broken per type icmp timeouts.
 20  *              Mike Shaver     :       RFC1122 checks.
 21  *              Alan Cox        :       Multicast ping reply as self.
 22  *              Alan Cox        :       Fix atomicity lockup in ip_build_xmit
 23  *                                      call.
 24  *              Alan Cox        :       Added 216,128 byte paths to the MTU
 25  *                                      code.
 26  *              Martin Mares    :       RFC1812 checks.
 27  *              Martin Mares    :       Can be configured to follow redirects
 28  *                                      if acting as a router _without_ a
 29  *                                      routing protocol (RFC 1812).
 30  *              Martin Mares    :       Echo requests may be configured to
 31  *                                      be ignored (RFC 1812).
 32  *              Martin Mares    :       Limitation of ICMP error message
 33  *                                      transmit rate (RFC 1812).
 34  *              Martin Mares    :       TOS and Precedence set correctly
 35  *                                      (RFC 1812).
 36  *              Martin Mares    :       Now copying as much data from the
 37  *                                      original packet as we can without
 38  *                                      exceeding 576 bytes (RFC 1812).
 39  *      Willy Konynenberg       :       Transparent proxying support.
 40  *              Keith Owens     :       RFC1191 correction for 4.2BSD based
 41  *                                      path MTU bug.
 42  *              Thomas Quinot   :       ICMP Dest Unreach codes up to 15 are
 43  *                                      valid (RFC 1812).
 44  *              Andi Kleen      :       Check all packet lengths properly
 45  *                                      and moved all kfree_skb() up to
 46  *                                      icmp_rcv.
 47  *              Andi Kleen      :       Move the rate limit bookkeeping
 48  *                                      into the dest entry and use a token
 49  *                                      bucket filter (thanks to ANK). Make
 50  *                                      the rates sysctl configurable.
 51  *              Yu Tianli       :       Fixed two ugly bugs in icmp_send
 52  *                                      - IP option length was accounted wrongly
 53  *                                      - ICMP header length was not accounted
 54  *                                        at all.
 55  *              Tristan Greaves :       Added sysctl option to ignore bogus
 56  *                                      broadcast responses from broken routers.
 57  *
 58  * To Fix:
 59  *
 60  *      - Should use skb_pull() instead of all the manual checking.
 61  *        This would also greatly simply some upper layer error handlers. --AK
 62  *
 63  */
 64 
 65 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 66 
 67 #include <linux/module.h>
 68 #include <linux/types.h>
 69 #include <linux/jiffies.h>
 70 #include <linux/kernel.h>
 71 #include <linux/fcntl.h>
 72 #include <linux/socket.h>
 73 #include <linux/in.h>
 74 #include <linux/inet.h>
 75 #include <linux/inetdevice.h>
 76 #include <linux/netdevice.h>
 77 #include <linux/string.h>
 78 #include <linux/netfilter_ipv4.h>
 79 #include <linux/slab.h>
 80 #include <net/snmp.h>
 81 #include <net/ip.h>
 82 #include <net/route.h>
 83 #include <net/protocol.h>
 84 #include <net/icmp.h>
 85 #include <net/tcp.h>
 86 #include <net/udp.h>
 87 #include <net/raw.h>
 88 #include <net/ping.h>
 89 #include <linux/skbuff.h>
 90 #include <net/sock.h>
 91 #include <linux/errno.h>
 92 #include <linux/timer.h>
 93 #include <linux/init.h>
 94 #include <asm/uaccess.h>
 95 #include <net/checksum.h>
 96 #include <net/xfrm.h>
 97 #include <net/inet_common.h>
 98 #include <net/ip_fib.h>
 99 #include <net/l3mdev.h>
100 
101 /*
102  *      Build xmit assembly blocks
103  */
104 
105 struct icmp_bxm {
106         struct sk_buff *skb;
107         int offset;
108         int data_len;
109 
110         struct {
111                 struct icmphdr icmph;
112                 __be32         times[3];
113         } data;
114         int head_len;
115         struct ip_options_data replyopts;
116 };
117 
118 /* An array of errno for error messages from dest unreach. */
119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
120 
121 const struct icmp_err icmp_err_convert[] = {
122         {
123                 .errno = ENETUNREACH,   /* ICMP_NET_UNREACH */
124                 .fatal = 0,
125         },
126         {
127                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNREACH */
128                 .fatal = 0,
129         },
130         {
131                 .errno = ENOPROTOOPT    /* ICMP_PROT_UNREACH */,
132                 .fatal = 1,
133         },
134         {
135                 .errno = ECONNREFUSED,  /* ICMP_PORT_UNREACH */
136                 .fatal = 1,
137         },
138         {
139                 .errno = EMSGSIZE,      /* ICMP_FRAG_NEEDED */
140                 .fatal = 0,
141         },
142         {
143                 .errno = EOPNOTSUPP,    /* ICMP_SR_FAILED */
144                 .fatal = 0,
145         },
146         {
147                 .errno = ENETUNREACH,   /* ICMP_NET_UNKNOWN */
148                 .fatal = 1,
149         },
150         {
151                 .errno = EHOSTDOWN,     /* ICMP_HOST_UNKNOWN */
152                 .fatal = 1,
153         },
154         {
155                 .errno = ENONET,        /* ICMP_HOST_ISOLATED */
156                 .fatal = 1,
157         },
158         {
159                 .errno = ENETUNREACH,   /* ICMP_NET_ANO */
160                 .fatal = 1,
161         },
162         {
163                 .errno = EHOSTUNREACH,  /* ICMP_HOST_ANO */
164                 .fatal = 1,
165         },
166         {
167                 .errno = ENETUNREACH,   /* ICMP_NET_UNR_TOS */
168                 .fatal = 0,
169         },
170         {
171                 .errno = EHOSTUNREACH,  /* ICMP_HOST_UNR_TOS */
172                 .fatal = 0,
173         },
174         {
175                 .errno = EHOSTUNREACH,  /* ICMP_PKT_FILTERED */
176                 .fatal = 1,
177         },
178         {
179                 .errno = EHOSTUNREACH,  /* ICMP_PREC_VIOLATION */
180                 .fatal = 1,
181         },
182         {
183                 .errno = EHOSTUNREACH,  /* ICMP_PREC_CUTOFF */
184                 .fatal = 1,
185         },
186 };
187 EXPORT_SYMBOL(icmp_err_convert);
188 
189 /*
190  *      ICMP control array. This specifies what to do with each ICMP.
191  */
192 
193 struct icmp_control {
194         bool (*handler)(struct sk_buff *skb);
195         short   error;          /* This ICMP is classed as an error message */
196 };
197 
198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
199 
200 /*
201  *      The ICMP socket(s). This is the most convenient way to flow control
202  *      our ICMP output as well as maintain a clean interface throughout
203  *      all layers. All Socketless IP sends will soon be gone.
204  *
205  *      On SMP we have one ICMP socket per-cpu.
206  */
207 static struct sock *icmp_sk(struct net *net)
208 {
209         return *this_cpu_ptr(net->ipv4.icmp_sk);
210 }
211 
212 static inline struct sock *icmp_xmit_lock(struct net *net)
213 {
214         struct sock *sk;
215 
216         local_bh_disable();
217 
218         sk = icmp_sk(net);
219 
220         if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
221                 /* This can happen if the output path signals a
222                  * dst_link_failure() for an outgoing ICMP packet.
223                  */
224                 local_bh_enable();
225                 return NULL;
226         }
227         return sk;
228 }
229 
230 static inline void icmp_xmit_unlock(struct sock *sk)
231 {
232         spin_unlock_bh(&sk->sk_lock.slock);
233 }
234 
235 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
236 int sysctl_icmp_msgs_burst __read_mostly = 50;
237 
238 static struct {
239         spinlock_t      lock;
240         u32             credit;
241         u32             stamp;
242 } icmp_global = {
243         .lock           = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
244 };
245 
246 /**
247  * icmp_global_allow - Are we allowed to send one more ICMP message ?
248  *
249  * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
250  * Returns false if we reached the limit and can not send another packet.
251  * Note: called with BH disabled
252  */
253 bool icmp_global_allow(void)
254 {
255         u32 credit, delta, incr = 0, now = (u32)jiffies;
256         bool rc = false;
257 
258         /* Check if token bucket is empty and cannot be refilled
259          * without taking the spinlock.
260          */
261         if (!icmp_global.credit) {
262                 delta = min_t(u32, now - icmp_global.stamp, HZ);
263                 if (delta < HZ / 50)
264                         return false;
265         }
266 
267         spin_lock(&icmp_global.lock);
268         delta = min_t(u32, now - icmp_global.stamp, HZ);
269         if (delta >= HZ / 50) {
270                 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
271                 if (incr)
272                         icmp_global.stamp = now;
273         }
274         credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
275         if (credit) {
276                 credit--;
277                 rc = true;
278         }
279         icmp_global.credit = credit;
280         spin_unlock(&icmp_global.lock);
281         return rc;
282 }
283 EXPORT_SYMBOL(icmp_global_allow);
284 
285 /*
286  *      Send an ICMP frame.
287  */
288 
289 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
290                                struct flowi4 *fl4, int type, int code)
291 {
292         struct dst_entry *dst = &rt->dst;
293         bool rc = true;
294 
295         if (type > NR_ICMP_TYPES)
296                 goto out;
297 
298         /* Don't limit PMTU discovery. */
299         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
300                 goto out;
301 
302         /* No rate limit on loopback */
303         if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
304                 goto out;
305 
306         /* Limit if icmp type is enabled in ratemask. */
307         if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
308                 goto out;
309 
310         rc = false;
311         if (icmp_global_allow()) {
312                 int vif = l3mdev_master_ifindex(dst->dev);
313                 struct inet_peer *peer;
314 
315                 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
316                 rc = inet_peer_xrlim_allow(peer,
317                                            net->ipv4.sysctl_icmp_ratelimit);
318                 if (peer)
319                         inet_putpeer(peer);
320         }
321 out:
322         return rc;
323 }
324 
325 /*
326  *      Maintain the counters used in the SNMP statistics for outgoing ICMP
327  */
328 void icmp_out_count(struct net *net, unsigned char type)
329 {
330         ICMPMSGOUT_INC_STATS(net, type);
331         ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
332 }
333 
334 /*
335  *      Checksum each fragment, and on the first include the headers and final
336  *      checksum.
337  */
338 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
339                           struct sk_buff *skb)
340 {
341         struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
342         __wsum csum;
343 
344         csum = skb_copy_and_csum_bits(icmp_param->skb,
345                                       icmp_param->offset + offset,
346                                       to, len, 0);
347 
348         skb->csum = csum_block_add(skb->csum, csum, odd);
349         if (icmp_pointers[icmp_param->data.icmph.type].error)
350                 nf_ct_attach(skb, icmp_param->skb);
351         return 0;
352 }
353 
354 static void icmp_push_reply(struct icmp_bxm *icmp_param,
355                             struct flowi4 *fl4,
356                             struct ipcm_cookie *ipc, struct rtable **rt)
357 {
358         struct sock *sk;
359         struct sk_buff *skb;
360 
361         sk = icmp_sk(dev_net((*rt)->dst.dev));
362         if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
363                            icmp_param->data_len+icmp_param->head_len,
364                            icmp_param->head_len,
365                            ipc, rt, MSG_DONTWAIT) < 0) {
366                 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
367                 ip_flush_pending_frames(sk);
368         } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
369                 struct icmphdr *icmph = icmp_hdr(skb);
370                 __wsum csum = 0;
371                 struct sk_buff *skb1;
372 
373                 skb_queue_walk(&sk->sk_write_queue, skb1) {
374                         csum = csum_add(csum, skb1->csum);
375                 }
376                 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
377                                                  (char *)icmph,
378                                                  icmp_param->head_len, csum);
379                 icmph->checksum = csum_fold(csum);
380                 skb->ip_summed = CHECKSUM_NONE;
381                 ip_push_pending_frames(sk, fl4);
382         }
383 }
384 
385 /*
386  *      Driving logic for building and sending ICMP messages.
387  */
388 
389 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
390 {
391         struct ipcm_cookie ipc;
392         struct rtable *rt = skb_rtable(skb);
393         struct net *net = dev_net(rt->dst.dev);
394         struct flowi4 fl4;
395         struct sock *sk;
396         struct inet_sock *inet;
397         __be32 daddr, saddr;
398         u32 mark = IP4_REPLY_MARK(net, skb->mark);
399 
400         if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
401                 return;
402 
403         sk = icmp_xmit_lock(net);
404         if (!sk)
405                 return;
406         inet = inet_sk(sk);
407 
408         icmp_param->data.icmph.checksum = 0;
409 
410         inet->tos = ip_hdr(skb)->tos;
411         sk->sk_mark = mark;
412         daddr = ipc.addr = ip_hdr(skb)->saddr;
413         saddr = fib_compute_spec_dst(skb);
414         ipc.opt = NULL;
415         ipc.tx_flags = 0;
416         ipc.ttl = 0;
417         ipc.tos = -1;
418 
419         if (icmp_param->replyopts.opt.opt.optlen) {
420                 ipc.opt = &icmp_param->replyopts.opt;
421                 if (ipc.opt->opt.srr)
422                         daddr = icmp_param->replyopts.opt.opt.faddr;
423         }
424         memset(&fl4, 0, sizeof(fl4));
425         fl4.daddr = daddr;
426         fl4.saddr = saddr;
427         fl4.flowi4_mark = mark;
428         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
429         fl4.flowi4_proto = IPPROTO_ICMP;
430         fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
431         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
432         rt = ip_route_output_key(net, &fl4);
433         if (IS_ERR(rt))
434                 goto out_unlock;
435         if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
436                                icmp_param->data.icmph.code))
437                 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
438         ip_rt_put(rt);
439 out_unlock:
440         icmp_xmit_unlock(sk);
441 }
442 
443 #ifdef CONFIG_IP_ROUTE_MULTIPATH
444 
445 /* Source and destination is swapped. See ip_multipath_icmp_hash */
446 static int icmp_multipath_hash_skb(const struct sk_buff *skb)
447 {
448         const struct iphdr *iph = ip_hdr(skb);
449 
450         return fib_multipath_hash(iph->daddr, iph->saddr);
451 }
452 
453 #else
454 
455 #define icmp_multipath_hash_skb(skb) (-1)
456 
457 #endif
458 
459 static struct rtable *icmp_route_lookup(struct net *net,
460                                         struct flowi4 *fl4,
461                                         struct sk_buff *skb_in,
462                                         const struct iphdr *iph,
463                                         __be32 saddr, u8 tos, u32 mark,
464                                         int type, int code,
465                                         struct icmp_bxm *param)
466 {
467         struct rtable *rt, *rt2;
468         struct flowi4 fl4_dec;
469         int err;
470 
471         memset(fl4, 0, sizeof(*fl4));
472         fl4->daddr = (param->replyopts.opt.opt.srr ?
473                       param->replyopts.opt.opt.faddr : iph->saddr);
474         fl4->saddr = saddr;
475         fl4->flowi4_mark = mark;
476         fl4->flowi4_tos = RT_TOS(tos);
477         fl4->flowi4_proto = IPPROTO_ICMP;
478         fl4->fl4_icmp_type = type;
479         fl4->fl4_icmp_code = code;
480         fl4->flowi4_oif = l3mdev_master_ifindex(skb_in->dev);
481 
482         security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
483         rt = __ip_route_output_key_hash(net, fl4,
484                                         icmp_multipath_hash_skb(skb_in));
485         if (IS_ERR(rt))
486                 return rt;
487 
488         /* No need to clone since we're just using its address. */
489         rt2 = rt;
490 
491         rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
492                                            flowi4_to_flowi(fl4), NULL, 0);
493         if (!IS_ERR(rt)) {
494                 if (rt != rt2)
495                         return rt;
496         } else if (PTR_ERR(rt) == -EPERM) {
497                 rt = NULL;
498         } else
499                 return rt;
500 
501         err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
502         if (err)
503                 goto relookup_failed;
504 
505         if (inet_addr_type_dev_table(net, skb_in->dev,
506                                      fl4_dec.saddr) == RTN_LOCAL) {
507                 rt2 = __ip_route_output_key(net, &fl4_dec);
508                 if (IS_ERR(rt2))
509                         err = PTR_ERR(rt2);
510         } else {
511                 struct flowi4 fl4_2 = {};
512                 unsigned long orefdst;
513 
514                 fl4_2.daddr = fl4_dec.saddr;
515                 rt2 = ip_route_output_key(net, &fl4_2);
516                 if (IS_ERR(rt2)) {
517                         err = PTR_ERR(rt2);
518                         goto relookup_failed;
519                 }
520                 /* Ugh! */
521                 orefdst = skb_in->_skb_refdst; /* save old refdst */
522                 skb_dst_set(skb_in, NULL);
523                 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
524                                      RT_TOS(tos), rt2->dst.dev);
525 
526                 dst_release(&rt2->dst);
527                 rt2 = skb_rtable(skb_in);
528                 skb_in->_skb_refdst = orefdst; /* restore old refdst */
529         }
530 
531         if (err)
532                 goto relookup_failed;
533 
534         rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
535                                             flowi4_to_flowi(&fl4_dec), NULL,
536                                             XFRM_LOOKUP_ICMP);
537         if (!IS_ERR(rt2)) {
538                 dst_release(&rt->dst);
539                 memcpy(fl4, &fl4_dec, sizeof(*fl4));
540                 rt = rt2;
541         } else if (PTR_ERR(rt2) == -EPERM) {
542                 if (rt)
543                         dst_release(&rt->dst);
544                 return rt2;
545         } else {
546                 err = PTR_ERR(rt2);
547                 goto relookup_failed;
548         }
549         return rt;
550 
551 relookup_failed:
552         if (rt)
553                 return rt;
554         return ERR_PTR(err);
555 }
556 
557 /*
558  *      Send an ICMP message in response to a situation
559  *
560  *      RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
561  *                MAY send more (we do).
562  *                      MUST NOT change this header information.
563  *                      MUST NOT reply to a multicast/broadcast IP address.
564  *                      MUST NOT reply to a multicast/broadcast MAC address.
565  *                      MUST reply to only the first fragment.
566  */
567 
568 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
569 {
570         struct iphdr *iph;
571         int room;
572         struct icmp_bxm *icmp_param;
573         struct rtable *rt = skb_rtable(skb_in);
574         struct ipcm_cookie ipc;
575         struct flowi4 fl4;
576         __be32 saddr;
577         u8  tos;
578         u32 mark;
579         struct net *net;
580         struct sock *sk;
581 
582         if (!rt)
583                 goto out;
584         net = dev_net(rt->dst.dev);
585 
586         /*
587          *      Find the original header. It is expected to be valid, of course.
588          *      Check this, icmp_send is called from the most obscure devices
589          *      sometimes.
590          */
591         iph = ip_hdr(skb_in);
592 
593         if ((u8 *)iph < skb_in->head ||
594             (skb_network_header(skb_in) + sizeof(*iph)) >
595             skb_tail_pointer(skb_in))
596                 goto out;
597 
598         /*
599          *      No replies to physical multicast/broadcast
600          */
601         if (skb_in->pkt_type != PACKET_HOST)
602                 goto out;
603 
604         /*
605          *      Now check at the protocol level
606          */
607         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
608                 goto out;
609 
610         /*
611          *      Only reply to fragment 0. We byte re-order the constant
612          *      mask for efficiency.
613          */
614         if (iph->frag_off & htons(IP_OFFSET))
615                 goto out;
616 
617         /*
618          *      If we send an ICMP error to an ICMP error a mess would result..
619          */
620         if (icmp_pointers[type].error) {
621                 /*
622                  *      We are an error, check if we are replying to an
623                  *      ICMP error
624                  */
625                 if (iph->protocol == IPPROTO_ICMP) {
626                         u8 _inner_type, *itp;
627 
628                         itp = skb_header_pointer(skb_in,
629                                                  skb_network_header(skb_in) +
630                                                  (iph->ihl << 2) +
631                                                  offsetof(struct icmphdr,
632                                                           type) -
633                                                  skb_in->data,
634                                                  sizeof(_inner_type),
635                                                  &_inner_type);
636                         if (!itp)
637                                 goto out;
638 
639                         /*
640                          *      Assume any unknown ICMP type is an error. This
641                          *      isn't specified by the RFC, but think about it..
642                          */
643                         if (*itp > NR_ICMP_TYPES ||
644                             icmp_pointers[*itp].error)
645                                 goto out;
646                 }
647         }
648 
649         icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
650         if (!icmp_param)
651                 return;
652 
653         sk = icmp_xmit_lock(net);
654         if (!sk)
655                 goto out_free;
656 
657         /*
658          *      Construct source address and options.
659          */
660 
661         saddr = iph->daddr;
662         if (!(rt->rt_flags & RTCF_LOCAL)) {
663                 struct net_device *dev = NULL;
664 
665                 rcu_read_lock();
666                 if (rt_is_input_route(rt) &&
667                     net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
668                         dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
669 
670                 if (dev)
671                         saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
672                 else
673                         saddr = 0;
674                 rcu_read_unlock();
675         }
676 
677         tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
678                                            IPTOS_PREC_INTERNETCONTROL) :
679                                           iph->tos;
680         mark = IP4_REPLY_MARK(net, skb_in->mark);
681 
682         if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
683                 goto out_unlock;
684 
685 
686         /*
687          *      Prepare data for ICMP header.
688          */
689 
690         icmp_param->data.icmph.type      = type;
691         icmp_param->data.icmph.code      = code;
692         icmp_param->data.icmph.un.gateway = info;
693         icmp_param->data.icmph.checksum  = 0;
694         icmp_param->skb   = skb_in;
695         icmp_param->offset = skb_network_offset(skb_in);
696         inet_sk(sk)->tos = tos;
697         sk->sk_mark = mark;
698         ipc.addr = iph->saddr;
699         ipc.opt = &icmp_param->replyopts.opt;
700         ipc.tx_flags = 0;
701         ipc.ttl = 0;
702         ipc.tos = -1;
703 
704         rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
705                                type, code, icmp_param);
706         if (IS_ERR(rt))
707                 goto out_unlock;
708 
709         if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
710                 goto ende;
711 
712         /* RFC says return as much as we can without exceeding 576 bytes. */
713 
714         room = dst_mtu(&rt->dst);
715         if (room > 576)
716                 room = 576;
717         room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
718         room -= sizeof(struct icmphdr);
719 
720         icmp_param->data_len = skb_in->len - icmp_param->offset;
721         if (icmp_param->data_len > room)
722                 icmp_param->data_len = room;
723         icmp_param->head_len = sizeof(struct icmphdr);
724 
725         icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
726 ende:
727         ip_rt_put(rt);
728 out_unlock:
729         icmp_xmit_unlock(sk);
730 out_free:
731         kfree(icmp_param);
732 out:;
733 }
734 EXPORT_SYMBOL(icmp_send);
735 
736 
737 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
738 {
739         const struct iphdr *iph = (const struct iphdr *) skb->data;
740         const struct net_protocol *ipprot;
741         int protocol = iph->protocol;
742 
743         /* Checkin full IP header plus 8 bytes of protocol to
744          * avoid additional coding at protocol handlers.
745          */
746         if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
747                 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
748                 return;
749         }
750 
751         raw_icmp_error(skb, protocol, info);
752 
753         ipprot = rcu_dereference(inet_protos[protocol]);
754         if (ipprot && ipprot->err_handler)
755                 ipprot->err_handler(skb, info);
756 }
757 
758 static bool icmp_tag_validation(int proto)
759 {
760         bool ok;
761 
762         rcu_read_lock();
763         ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
764         rcu_read_unlock();
765         return ok;
766 }
767 
768 /*
769  *      Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
770  *      ICMP_PARAMETERPROB.
771  */
772 
773 static bool icmp_unreach(struct sk_buff *skb)
774 {
775         const struct iphdr *iph;
776         struct icmphdr *icmph;
777         struct net *net;
778         u32 info = 0;
779 
780         net = dev_net(skb_dst(skb)->dev);
781 
782         /*
783          *      Incomplete header ?
784          *      Only checks for the IP header, there should be an
785          *      additional check for longer headers in upper levels.
786          */
787 
788         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
789                 goto out_err;
790 
791         icmph = icmp_hdr(skb);
792         iph   = (const struct iphdr *)skb->data;
793 
794         if (iph->ihl < 5) /* Mangled header, drop. */
795                 goto out_err;
796 
797         if (icmph->type == ICMP_DEST_UNREACH) {
798                 switch (icmph->code & 15) {
799                 case ICMP_NET_UNREACH:
800                 case ICMP_HOST_UNREACH:
801                 case ICMP_PROT_UNREACH:
802                 case ICMP_PORT_UNREACH:
803                         break;
804                 case ICMP_FRAG_NEEDED:
805                         /* for documentation of the ip_no_pmtu_disc
806                          * values please see
807                          * Documentation/networking/ip-sysctl.txt
808                          */
809                         switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
810                         default:
811                                 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
812                                                     &iph->daddr);
813                                 break;
814                         case 2:
815                                 goto out;
816                         case 3:
817                                 if (!icmp_tag_validation(iph->protocol))
818                                         goto out;
819                                 /* fall through */
820                         case 0:
821                                 info = ntohs(icmph->un.frag.mtu);
822                         }
823                         break;
824                 case ICMP_SR_FAILED:
825                         net_dbg_ratelimited("%pI4: Source Route Failed\n",
826                                             &iph->daddr);
827                         break;
828                 default:
829                         break;
830                 }
831                 if (icmph->code > NR_ICMP_UNREACH)
832                         goto out;
833         } else if (icmph->type == ICMP_PARAMETERPROB)
834                 info = ntohl(icmph->un.gateway) >> 24;
835 
836         /*
837          *      Throw it at our lower layers
838          *
839          *      RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
840          *                header.
841          *      RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
842          *                transport layer.
843          *      RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
844          *                transport layer.
845          */
846 
847         /*
848          *      Check the other end isn't violating RFC 1122. Some routers send
849          *      bogus responses to broadcast frames. If you see this message
850          *      first check your netmask matches at both ends, if it does then
851          *      get the other vendor to fix their kit.
852          */
853 
854         if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
855             inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
856                 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
857                                      &ip_hdr(skb)->saddr,
858                                      icmph->type, icmph->code,
859                                      &iph->daddr, skb->dev->name);
860                 goto out;
861         }
862 
863         icmp_socket_deliver(skb, info);
864 
865 out:
866         return true;
867 out_err:
868         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
869         return false;
870 }
871 
872 
873 /*
874  *      Handle ICMP_REDIRECT.
875  */
876 
877 static bool icmp_redirect(struct sk_buff *skb)
878 {
879         if (skb->len < sizeof(struct iphdr)) {
880                 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
881                 return false;
882         }
883 
884         if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
885                 /* there aught to be a stat */
886                 return false;
887         }
888 
889         icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
890         return true;
891 }
892 
893 /*
894  *      Handle ICMP_ECHO ("ping") requests.
895  *
896  *      RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
897  *                requests.
898  *      RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
899  *                included in the reply.
900  *      RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
901  *                echo requests, MUST have default=NOT.
902  *      See also WRT handling of options once they are done and working.
903  */
904 
905 static bool icmp_echo(struct sk_buff *skb)
906 {
907         struct net *net;
908 
909         net = dev_net(skb_dst(skb)->dev);
910         if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
911                 struct icmp_bxm icmp_param;
912 
913                 icmp_param.data.icmph      = *icmp_hdr(skb);
914                 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
915                 icmp_param.skb             = skb;
916                 icmp_param.offset          = 0;
917                 icmp_param.data_len        = skb->len;
918                 icmp_param.head_len        = sizeof(struct icmphdr);
919                 icmp_reply(&icmp_param, skb);
920         }
921         /* should there be an ICMP stat for ignored echos? */
922         return true;
923 }
924 
925 /*
926  *      Handle ICMP Timestamp requests.
927  *      RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
928  *                SHOULD be in the kernel for minimum random latency.
929  *                MUST be accurate to a few minutes.
930  *                MUST be updated at least at 15Hz.
931  */
932 static bool icmp_timestamp(struct sk_buff *skb)
933 {
934         struct timespec tv;
935         struct icmp_bxm icmp_param;
936         /*
937          *      Too short.
938          */
939         if (skb->len < 4)
940                 goto out_err;
941 
942         /*
943          *      Fill in the current time as ms since midnight UT:
944          */
945         getnstimeofday(&tv);
946         icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
947                                          tv.tv_nsec / NSEC_PER_MSEC);
948         icmp_param.data.times[2] = icmp_param.data.times[1];
949         if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
950                 BUG();
951         icmp_param.data.icmph      = *icmp_hdr(skb);
952         icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
953         icmp_param.data.icmph.code = 0;
954         icmp_param.skb             = skb;
955         icmp_param.offset          = 0;
956         icmp_param.data_len        = 0;
957         icmp_param.head_len        = sizeof(struct icmphdr) + 12;
958         icmp_reply(&icmp_param, skb);
959         return true;
960 
961 out_err:
962         ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
963         return false;
964 }
965 
966 static bool icmp_discard(struct sk_buff *skb)
967 {
968         /* pretend it was a success */
969         return true;
970 }
971 
972 /*
973  *      Deal with incoming ICMP packets.
974  */
975 int icmp_rcv(struct sk_buff *skb)
976 {
977         struct icmphdr *icmph;
978         struct rtable *rt = skb_rtable(skb);
979         struct net *net = dev_net(rt->dst.dev);
980         bool success;
981 
982         if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
983                 struct sec_path *sp = skb_sec_path(skb);
984                 int nh;
985 
986                 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
987                                  XFRM_STATE_ICMP))
988                         goto drop;
989 
990                 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
991                         goto drop;
992 
993                 nh = skb_network_offset(skb);
994                 skb_set_network_header(skb, sizeof(*icmph));
995 
996                 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
997                         goto drop;
998 
999                 skb_set_network_header(skb, nh);
1000         }
1001 
1002         ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
1003 
1004         if (skb_checksum_simple_validate(skb))
1005                 goto csum_error;
1006 
1007         if (!pskb_pull(skb, sizeof(*icmph)))
1008                 goto error;
1009 
1010         icmph = icmp_hdr(skb);
1011 
1012         ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1013         /*
1014          *      18 is the highest 'known' ICMP type. Anything else is a mystery
1015          *
1016          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
1017          *                discarded.
1018          */
1019         if (icmph->type > NR_ICMP_TYPES)
1020                 goto error;
1021 
1022 
1023         /*
1024          *      Parse the ICMP message
1025          */
1026 
1027         if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1028                 /*
1029                  *      RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1030                  *        silently ignored (we let user decide with a sysctl).
1031                  *      RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1032                  *        discarded if to broadcast/multicast.
1033                  */
1034                 if ((icmph->type == ICMP_ECHO ||
1035                      icmph->type == ICMP_TIMESTAMP) &&
1036                     net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1037                         goto error;
1038                 }
1039                 if (icmph->type != ICMP_ECHO &&
1040                     icmph->type != ICMP_TIMESTAMP &&
1041                     icmph->type != ICMP_ADDRESS &&
1042                     icmph->type != ICMP_ADDRESSREPLY) {
1043                         goto error;
1044                 }
1045         }
1046 
1047         success = icmp_pointers[icmph->type].handler(skb);
1048 
1049         if (success)  {
1050                 consume_skb(skb);
1051                 return 0;
1052         }
1053 
1054 drop:
1055         kfree_skb(skb);
1056         return 0;
1057 csum_error:
1058         ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
1059 error:
1060         ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1061         goto drop;
1062 }
1063 
1064 void icmp_err(struct sk_buff *skb, u32 info)
1065 {
1066         struct iphdr *iph = (struct iphdr *)skb->data;
1067         int offset = iph->ihl<<2;
1068         struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1069         int type = icmp_hdr(skb)->type;
1070         int code = icmp_hdr(skb)->code;
1071         struct net *net = dev_net(skb->dev);
1072 
1073         /*
1074          * Use ping_err to handle all icmp errors except those
1075          * triggered by ICMP_ECHOREPLY which sent from kernel.
1076          */
1077         if (icmph->type != ICMP_ECHOREPLY) {
1078                 ping_err(skb, offset, info);
1079                 return;
1080         }
1081 
1082         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1083                 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1084         else if (type == ICMP_REDIRECT)
1085                 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1086 }
1087 
1088 /*
1089  *      This table is the definition of how we handle ICMP.
1090  */
1091 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1092         [ICMP_ECHOREPLY] = {
1093                 .handler = ping_rcv,
1094         },
1095         [1] = {
1096                 .handler = icmp_discard,
1097                 .error = 1,
1098         },
1099         [2] = {
1100                 .handler = icmp_discard,
1101                 .error = 1,
1102         },
1103         [ICMP_DEST_UNREACH] = {
1104                 .handler = icmp_unreach,
1105                 .error = 1,
1106         },
1107         [ICMP_SOURCE_QUENCH] = {
1108                 .handler = icmp_unreach,
1109                 .error = 1,
1110         },
1111         [ICMP_REDIRECT] = {
1112                 .handler = icmp_redirect,
1113                 .error = 1,
1114         },
1115         [6] = {
1116                 .handler = icmp_discard,
1117                 .error = 1,
1118         },
1119         [7] = {
1120                 .handler = icmp_discard,
1121                 .error = 1,
1122         },
1123         [ICMP_ECHO] = {
1124                 .handler = icmp_echo,
1125         },
1126         [9] = {
1127                 .handler = icmp_discard,
1128                 .error = 1,
1129         },
1130         [10] = {
1131                 .handler = icmp_discard,
1132                 .error = 1,
1133         },
1134         [ICMP_TIME_EXCEEDED] = {
1135                 .handler = icmp_unreach,
1136                 .error = 1,
1137         },
1138         [ICMP_PARAMETERPROB] = {
1139                 .handler = icmp_unreach,
1140                 .error = 1,
1141         },
1142         [ICMP_TIMESTAMP] = {
1143                 .handler = icmp_timestamp,
1144         },
1145         [ICMP_TIMESTAMPREPLY] = {
1146                 .handler = icmp_discard,
1147         },
1148         [ICMP_INFO_REQUEST] = {
1149                 .handler = icmp_discard,
1150         },
1151         [ICMP_INFO_REPLY] = {
1152                 .handler = icmp_discard,
1153         },
1154         [ICMP_ADDRESS] = {
1155                 .handler = icmp_discard,
1156         },
1157         [ICMP_ADDRESSREPLY] = {
1158                 .handler = icmp_discard,
1159         },
1160 };
1161 
1162 static void __net_exit icmp_sk_exit(struct net *net)
1163 {
1164         int i;
1165 
1166         for_each_possible_cpu(i)
1167                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1168         free_percpu(net->ipv4.icmp_sk);
1169         net->ipv4.icmp_sk = NULL;
1170 }
1171 
1172 static int __net_init icmp_sk_init(struct net *net)
1173 {
1174         int i, err;
1175 
1176         net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1177         if (!net->ipv4.icmp_sk)
1178                 return -ENOMEM;
1179 
1180         for_each_possible_cpu(i) {
1181                 struct sock *sk;
1182 
1183                 err = inet_ctl_sock_create(&sk, PF_INET,
1184                                            SOCK_RAW, IPPROTO_ICMP, net);
1185                 if (err < 0)
1186                         goto fail;
1187 
1188                 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1189 
1190                 /* Enough space for 2 64K ICMP packets, including
1191                  * sk_buff/skb_shared_info struct overhead.
1192                  */
1193                 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1194 
1195                 /*
1196                  * Speedup sock_wfree()
1197                  */
1198                 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1199                 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1200         }
1201 
1202         /* Control parameters for ECHO replies. */
1203         net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1204         net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1205 
1206         /* Control parameter - ignore bogus broadcast responses? */
1207         net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1208 
1209         /*
1210          *      Configurable global rate limit.
1211          *
1212          *      ratelimit defines tokens/packet consumed for dst->rate_token
1213          *      bucket ratemask defines which icmp types are ratelimited by
1214          *      setting it's bit position.
1215          *
1216          *      default:
1217          *      dest unreachable (3), source quench (4),
1218          *      time exceeded (11), parameter problem (12)
1219          */
1220 
1221         net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1222         net->ipv4.sysctl_icmp_ratemask = 0x1818;
1223         net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1224 
1225         return 0;
1226 
1227 fail:
1228         for_each_possible_cpu(i)
1229                 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1230         free_percpu(net->ipv4.icmp_sk);
1231         return err;
1232 }
1233 
1234 static struct pernet_operations __net_initdata icmp_sk_ops = {
1235        .init = icmp_sk_init,
1236        .exit = icmp_sk_exit,
1237 };
1238 
1239 int __init icmp_init(void)
1240 {
1241         return register_pernet_subsys(&icmp_sk_ops);
1242 }
1243 

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