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CommitLineData
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#include <linux/module.h>
66#include <linux/types.h>
67#include <linux/jiffies.h>
68#include <linux/kernel.h>
69#include <linux/fcntl.h>
70#include <linux/socket.h>
71#include <linux/in.h>
72#include <linux/inet.h>
73#include <linux/inetdevice.h>
74#include <linux/netdevice.h>
75#include <linux/string.h>
76#include <linux/netfilter_ipv4.h>
77#include <linux/slab.h>
78#include <net/snmp.h>
79#include <net/ip.h>
80#include <net/route.h>
81#include <net/protocol.h>
82#include <net/icmp.h>
83#include <net/tcp.h>
84#include <net/udp.h>
85#include <net/raw.h>
86#include <linux/skbuff.h>
87#include <net/sock.h>
88#include <linux/errno.h>
89#include <linux/timer.h>
90#include <linux/init.h>
91#include <asm/system.h>
92#include <asm/uaccess.h>
93#include <net/checksum.h>
94#include <net/xfrm.h>
95#include <net/inet_common.h>
96
97/*
98 * Build xmit assembly blocks
99 */
100
101struct icmp_bxm {
102 struct sk_buff *skb;
103 int offset;
104 int data_len;
105
106 struct {
107 struct icmphdr icmph;
108 __be32 times[3];
109 } data;
110 int head_len;
111 struct ip_options replyopts;
112 unsigned char optbuf[40];
113};
114
115/* An array of errno for error messages from dest unreach. */
116/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
117
118const struct icmp_err icmp_err_convert[] = {
119 {
120 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
121 .fatal = 0,
122 },
123 {
124 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
125 .fatal = 0,
126 },
127 {
128 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
129 .fatal = 1,
130 },
131 {
132 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
133 .fatal = 1,
134 },
135 {
136 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
137 .fatal = 0,
138 },
139 {
140 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
141 .fatal = 0,
142 },
143 {
144 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
145 .fatal = 1,
146 },
147 {
148 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
149 .fatal = 1,
150 },
151 {
152 .errno = ENONET, /* ICMP_HOST_ISOLATED */
153 .fatal = 1,
154 },
155 {
156 .errno = ENETUNREACH, /* ICMP_NET_ANO */
157 .fatal = 1,
158 },
159 {
160 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
161 .fatal = 1,
162 },
163 {
164 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
165 .fatal = 0,
166 },
167 {
168 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
169 .fatal = 0,
170 },
171 {
172 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
173 .fatal = 1,
174 },
175 {
176 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
177 .fatal = 1,
178 },
179 {
180 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
181 .fatal = 1,
182 },
183};
184
185/*
186 * ICMP control array. This specifies what to do with each ICMP.
187 */
188
189struct icmp_control {
190 void (*handler)(struct sk_buff *skb);
191 short error; /* This ICMP is classed as an error message */
192};
193
194static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
195
196/*
197 * The ICMP socket(s). This is the most convenient way to flow control
198 * our ICMP output as well as maintain a clean interface throughout
199 * all layers. All Socketless IP sends will soon be gone.
200 *
201 * On SMP we have one ICMP socket per-cpu.
202 */
203static struct sock *icmp_sk(struct net *net)
204{
205 return net->ipv4.icmp_sk[smp_processor_id()];
206}
207
208static inline struct sock *icmp_xmit_lock(struct net *net)
209{
210 struct sock *sk;
211
212 local_bh_disable();
213
214 sk = icmp_sk(net);
215
216 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
217 /* This can happen if the output path signals a
218 * dst_link_failure() for an outgoing ICMP packet.
219 */
220 local_bh_enable();
221 return NULL;
222 }
223 return sk;
224}
225
226static inline void icmp_xmit_unlock(struct sock *sk)
227{
228 spin_unlock_bh(&sk->sk_lock.slock);
229}
230
231/*
232 * Send an ICMP frame.
233 */
234
235/*
236 * Check transmit rate limitation for given message.
237 * The rate information is held in the destination cache now.
238 * This function is generic and could be used for other purposes
239 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
240 *
241 * Note that the same dst_entry fields are modified by functions in
242 * route.c too, but these work for packet destinations while xrlim_allow
243 * works for icmp destinations. This means the rate limiting information
244 * for one "ip object" is shared - and these ICMPs are twice limited:
245 * by source and by destination.
246 *
247 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
248 * SHOULD allow setting of rate limits
249 *
250 * Shared between ICMPv4 and ICMPv6.
251 */
252#define XRLIM_BURST_FACTOR 6
253int xrlim_allow(struct dst_entry *dst, int timeout)
254{
255 unsigned long now, token = dst->rate_tokens;
256 int rc = 0;
257
258 now = jiffies;
259 token += now - dst->rate_last;
260 dst->rate_last = now;
261 if (token > XRLIM_BURST_FACTOR * timeout)
262 token = XRLIM_BURST_FACTOR * timeout;
263 if (token >= timeout) {
264 token -= timeout;
265 rc = 1;
266 }
267 dst->rate_tokens = token;
268 return rc;
269}
270
271static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
272 int type, int code)
273{
274 struct dst_entry *dst = &rt->u.dst;
275 int rc = 1;
276
277 if (type > NR_ICMP_TYPES)
278 goto out;
279
280 /* Don't limit PMTU discovery. */
281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
282 goto out;
283
284 /* No rate limit on loopback */
285 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
286 goto out;
287
288 /* Limit if icmp type is enabled in ratemask. */
289 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
290 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
291out:
292 return rc;
293}
294
295/*
296 * Maintain the counters used in the SNMP statistics for outgoing ICMP
297 */
298void icmp_out_count(struct net *net, unsigned char type)
299{
300 ICMPMSGOUT_INC_STATS(net, type);
301 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
302}
303
304/*
305 * Checksum each fragment, and on the first include the headers and final
306 * checksum.
307 */
308static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
309 struct sk_buff *skb)
310{
311 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
312 __wsum csum;
313
314 csum = skb_copy_and_csum_bits(icmp_param->skb,
315 icmp_param->offset + offset,
316 to, len, 0);
317
318 skb->csum = csum_block_add(skb->csum, csum, odd);
319 if (icmp_pointers[icmp_param->data.icmph.type].error)
320 nf_ct_attach(skb, icmp_param->skb);
321 return 0;
322}
323
324static void icmp_push_reply(struct icmp_bxm *icmp_param,
325 struct ipcm_cookie *ipc, struct rtable **rt)
326{
327 struct sock *sk;
328 struct sk_buff *skb;
329
330 sk = icmp_sk(dev_net((*rt)->u.dst.dev));
331 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
332 icmp_param->data_len+icmp_param->head_len,
333 icmp_param->head_len,
334 ipc, rt, MSG_DONTWAIT) < 0) {
335 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
336 ip_flush_pending_frames(sk);
337 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
338 struct icmphdr *icmph = icmp_hdr(skb);
339 __wsum csum = 0;
340 struct sk_buff *skb1;
341
342 skb_queue_walk(&sk->sk_write_queue, skb1) {
343 csum = csum_add(csum, skb1->csum);
344 }
345 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
346 (char *)icmph,
347 icmp_param->head_len, csum);
348 icmph->checksum = csum_fold(csum);
349 skb->ip_summed = CHECKSUM_NONE;
350 ip_push_pending_frames(sk);
351 }
352}
353
354/*
355 * Driving logic for building and sending ICMP messages.
356 */
357
358static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
359{
360 struct ipcm_cookie ipc;
361 struct rtable *rt = skb_rtable(skb);
362 struct net *net = dev_net(rt->u.dst.dev);
363 struct sock *sk;
364 struct inet_sock *inet;
365 __be32 daddr;
366
367 if (ip_options_echo(&icmp_param->replyopts, skb))
368 return;
369
370 sk = icmp_xmit_lock(net);
371 if (sk == NULL)
372 return;
373 inet = inet_sk(sk);
374
375 icmp_param->data.icmph.checksum = 0;
376
377 inet->tos = ip_hdr(skb)->tos;
378 daddr = ipc.addr = rt->rt_src;
379 ipc.opt = NULL;
380 ipc.shtx.flags = 0;
381 if (icmp_param->replyopts.optlen) {
382 ipc.opt = &icmp_param->replyopts;
383 if (ipc.opt->srr)
384 daddr = icmp_param->replyopts.faddr;
385 }
386 {
387 struct flowi fl = { .nl_u = { .ip4_u =
388 { .daddr = daddr,
389 .saddr = rt->rt_spec_dst,
390 .tos = RT_TOS(ip_hdr(skb)->tos) } },
391 .proto = IPPROTO_ICMP };
392 security_skb_classify_flow(skb, &fl);
393 if (ip_route_output_key(net, &rt, &fl))
394 goto out_unlock;
395 }
396 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
397 icmp_param->data.icmph.code))
398 icmp_push_reply(icmp_param, &ipc, &rt);
399 ip_rt_put(rt);
400out_unlock:
401 icmp_xmit_unlock(sk);
402}
403
404
405/*
406 * Send an ICMP message in response to a situation
407 *
408 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
409 * MAY send more (we do).
410 * MUST NOT change this header information.
411 * MUST NOT reply to a multicast/broadcast IP address.
412 * MUST NOT reply to a multicast/broadcast MAC address.
413 * MUST reply to only the first fragment.
414 */
415
416void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
417{
418 struct iphdr *iph;
419 int room;
420 struct icmp_bxm icmp_param;
421 struct rtable *rt = skb_rtable(skb_in);
422 struct ipcm_cookie ipc;
423 __be32 saddr;
424 u8 tos;
425 struct net *net;
426 struct sock *sk;
427
428 if (!rt)
429 goto out;
430 net = dev_net(rt->u.dst.dev);
431
432 /*
433 * Find the original header. It is expected to be valid, of course.
434 * Check this, icmp_send is called from the most obscure devices
435 * sometimes.
436 */
437 iph = ip_hdr(skb_in);
438
439 if ((u8 *)iph < skb_in->head ||
440 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
441 goto out;
442
443 /*
444 * No replies to physical multicast/broadcast
445 */
446 if (skb_in->pkt_type != PACKET_HOST)
447 goto out;
448
449 /*
450 * Now check at the protocol level
451 */
452 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
453 goto out;
454
455 /*
456 * Only reply to fragment 0. We byte re-order the constant
457 * mask for efficiency.
458 */
459 if (iph->frag_off & htons(IP_OFFSET))
460 goto out;
461
462 /*
463 * If we send an ICMP error to an ICMP error a mess would result..
464 */
465 if (icmp_pointers[type].error) {
466 /*
467 * We are an error, check if we are replying to an
468 * ICMP error
469 */
470 if (iph->protocol == IPPROTO_ICMP) {
471 u8 _inner_type, *itp;
472
473 itp = skb_header_pointer(skb_in,
474 skb_network_header(skb_in) +
475 (iph->ihl << 2) +
476 offsetof(struct icmphdr,
477 type) -
478 skb_in->data,
479 sizeof(_inner_type),
480 &_inner_type);
481 if (itp == NULL)
482 goto out;
483
484 /*
485 * Assume any unknown ICMP type is an error. This
486 * isn't specified by the RFC, but think about it..
487 */
488 if (*itp > NR_ICMP_TYPES ||
489 icmp_pointers[*itp].error)
490 goto out;
491 }
492 }
493
494 sk = icmp_xmit_lock(net);
495 if (sk == NULL)
496 return;
497
498 /*
499 * Construct source address and options.
500 */
501
502 saddr = iph->daddr;
503 if (!(rt->rt_flags & RTCF_LOCAL)) {
504 struct net_device *dev = NULL;
505
506 rcu_read_lock();
507 if (rt->fl.iif &&
508 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
509 dev = dev_get_by_index_rcu(net, rt->fl.iif);
510
511 if (dev)
512 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
513 else
514 saddr = 0;
515 rcu_read_unlock();
516 }
517
518 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
519 IPTOS_PREC_INTERNETCONTROL) :
520 iph->tos;
521
522 if (ip_options_echo(&icmp_param.replyopts, skb_in))
523 goto out_unlock;
524
525
526 /*
527 * Prepare data for ICMP header.
528 */
529
530 icmp_param.data.icmph.type = type;
531 icmp_param.data.icmph.code = code;
532 icmp_param.data.icmph.un.gateway = info;
533 icmp_param.data.icmph.checksum = 0;
534 icmp_param.skb = skb_in;
535 icmp_param.offset = skb_network_offset(skb_in);
536 inet_sk(sk)->tos = tos;
537 ipc.addr = iph->saddr;
538 ipc.opt = &icmp_param.replyopts;
539 ipc.shtx.flags = 0;
540
541 {
542 struct flowi fl = {
543 .nl_u = {
544 .ip4_u = {
545 .daddr = icmp_param.replyopts.srr ?
546 icmp_param.replyopts.faddr :
547 iph->saddr,
548 .saddr = saddr,
549 .tos = RT_TOS(tos)
550 }
551 },
552 .proto = IPPROTO_ICMP,
553 .uli_u = {
554 .icmpt = {
555 .type = type,
556 .code = code
557 }
558 }
559 };
560 int err;
561 struct rtable *rt2;
562
563 security_skb_classify_flow(skb_in, &fl);
564 if (__ip_route_output_key(net, &rt, &fl))
565 goto out_unlock;
566
567 /* No need to clone since we're just using its address. */
568 rt2 = rt;
569
570 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
571 switch (err) {
572 case 0:
573 if (rt != rt2)
574 goto route_done;
575 break;
576 case -EPERM:
577 rt = NULL;
578 break;
579 default:
580 goto out_unlock;
581 }
582
583 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
584 goto relookup_failed;
585
586 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
587 err = __ip_route_output_key(net, &rt2, &fl);
588 else {
589 struct flowi fl2 = {};
590 unsigned long orefdst;
591
592 fl2.fl4_dst = fl.fl4_src;
593 if (ip_route_output_key(net, &rt2, &fl2))
594 goto relookup_failed;
595
596 /* Ugh! */
597 orefdst = skb_in->_skb_refdst; /* save old refdst */
598 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
599 RT_TOS(tos), rt2->u.dst.dev);
600
601 dst_release(&rt2->u.dst);
602 rt2 = skb_rtable(skb_in);
603 skb_in->_skb_refdst = orefdst; /* restore old refdst */
604 }
605
606 if (err)
607 goto relookup_failed;
608
609 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
610 XFRM_LOOKUP_ICMP);
611 switch (err) {
612 case 0:
613 dst_release(&rt->u.dst);
614 rt = rt2;
615 break;
616 case -EPERM:
617 goto ende;
618 default:
619relookup_failed:
620 if (!rt)
621 goto out_unlock;
622 break;
623 }
624 }
625
626route_done:
627 if (!icmpv4_xrlim_allow(net, rt, type, code))
628 goto ende;
629
630 /* RFC says return as much as we can without exceeding 576 bytes. */
631
632 room = dst_mtu(&rt->u.dst);
633 if (room > 576)
634 room = 576;
635 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
636 room -= sizeof(struct icmphdr);
637
638 icmp_param.data_len = skb_in->len - icmp_param.offset;
639 if (icmp_param.data_len > room)
640 icmp_param.data_len = room;
641 icmp_param.head_len = sizeof(struct icmphdr);
642
643 icmp_push_reply(&icmp_param, &ipc, &rt);
644ende:
645 ip_rt_put(rt);
646out_unlock:
647 icmp_xmit_unlock(sk);
648out:;
649}
650
651
652/*
653 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
654 */
655
656static void icmp_unreach(struct sk_buff *skb)
657{
658 struct iphdr *iph;
659 struct icmphdr *icmph;
660 int hash, protocol;
661 const struct net_protocol *ipprot;
662 u32 info = 0;
663 struct net *net;
664
665 net = dev_net(skb_dst(skb)->dev);
666
667 /*
668 * Incomplete header ?
669 * Only checks for the IP header, there should be an
670 * additional check for longer headers in upper levels.
671 */
672
673 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
674 goto out_err;
675
676 icmph = icmp_hdr(skb);
677 iph = (struct iphdr *)skb->data;
678
679 if (iph->ihl < 5) /* Mangled header, drop. */
680 goto out_err;
681
682 if (icmph->type == ICMP_DEST_UNREACH) {
683 switch (icmph->code & 15) {
684 case ICMP_NET_UNREACH:
685 case ICMP_HOST_UNREACH:
686 case ICMP_PROT_UNREACH:
687 case ICMP_PORT_UNREACH:
688 break;
689 case ICMP_FRAG_NEEDED:
690 if (ipv4_config.no_pmtu_disc) {
691 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
692 &iph->daddr);
693 } else {
694 info = ip_rt_frag_needed(net, iph,
695 ntohs(icmph->un.frag.mtu),
696 skb->dev);
697 if (!info)
698 goto out;
699 }
700 break;
701 case ICMP_SR_FAILED:
702 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
703 &iph->daddr);
704 break;
705 default:
706 break;
707 }
708 if (icmph->code > NR_ICMP_UNREACH)
709 goto out;
710 } else if (icmph->type == ICMP_PARAMETERPROB)
711 info = ntohl(icmph->un.gateway) >> 24;
712
713 /*
714 * Throw it at our lower layers
715 *
716 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
717 * header.
718 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
719 * transport layer.
720 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
721 * transport layer.
722 */
723
724 /*
725 * Check the other end isnt violating RFC 1122. Some routers send
726 * bogus responses to broadcast frames. If you see this message
727 * first check your netmask matches at both ends, if it does then
728 * get the other vendor to fix their kit.
729 */
730
731 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
732 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
733 if (net_ratelimit())
734 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
735 "type %u, code %u "
736 "error to a broadcast: %pI4 on %s\n",
737 &ip_hdr(skb)->saddr,
738 icmph->type, icmph->code,
739 &iph->daddr,
740 skb->dev->name);
741 goto out;
742 }
743
744 /* Checkin full IP header plus 8 bytes of protocol to
745 * avoid additional coding at protocol handlers.
746 */
747 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
748 goto out;
749
750 iph = (struct iphdr *)skb->data;
751 protocol = iph->protocol;
752
753 /*
754 * Deliver ICMP message to raw sockets. Pretty useless feature?
755 */
756 raw_icmp_error(skb, protocol, info);
757
758 hash = protocol & (MAX_INET_PROTOS - 1);
759 rcu_read_lock();
760 ipprot = rcu_dereference(inet_protos[hash]);
761 if (ipprot && ipprot->err_handler)
762 ipprot->err_handler(skb, info);
763 rcu_read_unlock();
764
765out:
766 return;
767out_err:
768 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
769 goto out;
770}
771
772
773/*
774 * Handle ICMP_REDIRECT.
775 */
776
777static void icmp_redirect(struct sk_buff *skb)
778{
779 struct iphdr *iph;
780
781 if (skb->len < sizeof(struct iphdr))
782 goto out_err;
783
784 /*
785 * Get the copied header of the packet that caused the redirect
786 */
787 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
788 goto out;
789
790 iph = (struct iphdr *)skb->data;
791
792 switch (icmp_hdr(skb)->code & 7) {
793 case ICMP_REDIR_NET:
794 case ICMP_REDIR_NETTOS:
795 /*
796 * As per RFC recommendations now handle it as a host redirect.
797 */
798 case ICMP_REDIR_HOST:
799 case ICMP_REDIR_HOSTTOS:
800 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
801 icmp_hdr(skb)->un.gateway,
802 iph->saddr, skb->dev);
803 break;
804 }
805out:
806 return;
807out_err:
808 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
809 goto out;
810}
811
812/*
813 * Handle ICMP_ECHO ("ping") requests.
814 *
815 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
816 * requests.
817 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
818 * included in the reply.
819 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
820 * echo requests, MUST have default=NOT.
821 * See also WRT handling of options once they are done and working.
822 */
823
824static void icmp_echo(struct sk_buff *skb)
825{
826 struct net *net;
827
828 net = dev_net(skb_dst(skb)->dev);
829 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
830 struct icmp_bxm icmp_param;
831
832 icmp_param.data.icmph = *icmp_hdr(skb);
833 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
834 icmp_param.skb = skb;
835 icmp_param.offset = 0;
836 icmp_param.data_len = skb->len;
837 icmp_param.head_len = sizeof(struct icmphdr);
838 icmp_reply(&icmp_param, skb);
839 }
840}
841
842/*
843 * Handle ICMP Timestamp requests.
844 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
845 * SHOULD be in the kernel for minimum random latency.
846 * MUST be accurate to a few minutes.
847 * MUST be updated at least at 15Hz.
848 */
849static void icmp_timestamp(struct sk_buff *skb)
850{
851 struct timespec tv;
852 struct icmp_bxm icmp_param;
853 /*
854 * Too short.
855 */
856 if (skb->len < 4)
857 goto out_err;
858
859 /*
860 * Fill in the current time as ms since midnight UT:
861 */
862 getnstimeofday(&tv);
863 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
864 tv.tv_nsec / NSEC_PER_MSEC);
865 icmp_param.data.times[2] = icmp_param.data.times[1];
866 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
867 BUG();
868 icmp_param.data.icmph = *icmp_hdr(skb);
869 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
870 icmp_param.data.icmph.code = 0;
871 icmp_param.skb = skb;
872 icmp_param.offset = 0;
873 icmp_param.data_len = 0;
874 icmp_param.head_len = sizeof(struct icmphdr) + 12;
875 icmp_reply(&icmp_param, skb);
876out:
877 return;
878out_err:
879 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
880 goto out;
881}
882
883
884/*
885 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
886 *
887 * RFC1122 (3.2.2.9). A host MUST only send replies to
888 * ADDRESS_MASK requests if it's been configured as an address mask
889 * agent. Receiving a request doesn't constitute implicit permission to
890 * act as one. Of course, implementing this correctly requires (SHOULD)
891 * a way to turn the functionality on and off. Another one for sysctl(),
892 * I guess. -- MS
893 *
894 * RFC1812 (4.3.3.9). A router MUST implement it.
895 * A router SHOULD have switch turning it on/off.
896 * This switch MUST be ON by default.
897 *
898 * Gratuitous replies, zero-source replies are not implemented,
899 * that complies with RFC. DO NOT implement them!!! All the idea
900 * of broadcast addrmask replies as specified in RFC950 is broken.
901 * The problem is that it is not uncommon to have several prefixes
902 * on one physical interface. Moreover, addrmask agent can even be
903 * not aware of existing another prefixes.
904 * If source is zero, addrmask agent cannot choose correct prefix.
905 * Gratuitous mask announcements suffer from the same problem.
906 * RFC1812 explains it, but still allows to use ADDRMASK,
907 * that is pretty silly. --ANK
908 *
909 * All these rules are so bizarre, that I removed kernel addrmask
910 * support at all. It is wrong, it is obsolete, nobody uses it in
911 * any case. --ANK
912 *
913 * Furthermore you can do it with a usermode address agent program
914 * anyway...
915 */
916
917static void icmp_address(struct sk_buff *skb)
918{
919#if 0
920 if (net_ratelimit())
921 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
922#endif
923}
924
925/*
926 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
927 * loudly if an inconsistency is found.
928 * called with rcu_read_lock()
929 */
930
931static void icmp_address_reply(struct sk_buff *skb)
932{
933 struct rtable *rt = skb_rtable(skb);
934 struct net_device *dev = skb->dev;
935 struct in_device *in_dev;
936 struct in_ifaddr *ifa;
937
938 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
939 return;
940
941 in_dev = __in_dev_get_rcu(dev);
942 if (!in_dev)
943 return;
944
945 if (in_dev->ifa_list &&
946 IN_DEV_LOG_MARTIANS(in_dev) &&
947 IN_DEV_FORWARD(in_dev)) {
948 __be32 _mask, *mp;
949
950 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
951 BUG_ON(mp == NULL);
952 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
953 if (*mp == ifa->ifa_mask &&
954 inet_ifa_match(rt->rt_src, ifa))
955 break;
956 }
957 if (!ifa && net_ratelimit()) {
958 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
959 mp, dev->name, &rt->rt_src);
960 }
961 }
962}
963
964static void icmp_discard(struct sk_buff *skb)
965{
966}
967
968/*
969 * Deal with incoming ICMP packets.
970 */
971int icmp_rcv(struct sk_buff *skb)
972{
973 struct icmphdr *icmph;
974 struct rtable *rt = skb_rtable(skb);
975 struct net *net = dev_net(rt->u.dst.dev);
976
977 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
978 struct sec_path *sp = skb_sec_path(skb);
979 int nh;
980
981 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
982 XFRM_STATE_ICMP))
983 goto drop;
984
985 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
986 goto drop;
987
988 nh = skb_network_offset(skb);
989 skb_set_network_header(skb, sizeof(*icmph));
990
991 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
992 goto drop;
993
994 skb_set_network_header(skb, nh);
995 }
996
997 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
998
999 switch (skb->ip_summed) {
1000 case CHECKSUM_COMPLETE:
1001 if (!csum_fold(skb->csum))
1002 break;
1003 /* fall through */
1004 case CHECKSUM_NONE:
1005 skb->csum = 0;
1006 if (__skb_checksum_complete(skb))
1007 goto error;
1008 }
1009
1010 if (!pskb_pull(skb, sizeof(*icmph)))
1011 goto error;
1012
1013 icmph = icmp_hdr(skb);
1014
1015 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1016 /*
1017 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1018 *
1019 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1020 * discarded.
1021 */
1022 if (icmph->type > NR_ICMP_TYPES)
1023 goto error;
1024
1025
1026 /*
1027 * Parse the ICMP message
1028 */
1029
1030 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1031 /*
1032 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1033 * silently ignored (we let user decide with a sysctl).
1034 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1035 * discarded if to broadcast/multicast.
1036 */
1037 if ((icmph->type == ICMP_ECHO ||
1038 icmph->type == ICMP_TIMESTAMP) &&
1039 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1040 goto error;
1041 }
1042 if (icmph->type != ICMP_ECHO &&
1043 icmph->type != ICMP_TIMESTAMP &&
1044 icmph->type != ICMP_ADDRESS &&
1045 icmph->type != ICMP_ADDRESSREPLY) {
1046 goto error;
1047 }
1048 }
1049
1050 icmp_pointers[icmph->type].handler(skb);
1051
1052drop:
1053 kfree_skb(skb);
1054 return 0;
1055error:
1056 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1057 goto drop;
1058}
1059
1060/*
1061 * This table is the definition of how we handle ICMP.
1062 */
1063static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1064 [ICMP_ECHOREPLY] = {
1065 .handler = icmp_discard,
1066 },
1067 [1] = {
1068 .handler = icmp_discard,
1069 .error = 1,
1070 },
1071 [2] = {
1072 .handler = icmp_discard,
1073 .error = 1,
1074 },
1075 [ICMP_DEST_UNREACH] = {
1076 .handler = icmp_unreach,
1077 .error = 1,
1078 },
1079 [ICMP_SOURCE_QUENCH] = {
1080 .handler = icmp_unreach,
1081 .error = 1,
1082 },
1083 [ICMP_REDIRECT] = {
1084 .handler = icmp_redirect,
1085 .error = 1,
1086 },
1087 [6] = {
1088 .handler = icmp_discard,
1089 .error = 1,
1090 },
1091 [7] = {
1092 .handler = icmp_discard,
1093 .error = 1,
1094 },
1095 [ICMP_ECHO] = {
1096 .handler = icmp_echo,
1097 },
1098 [9] = {
1099 .handler = icmp_discard,
1100 .error = 1,
1101 },
1102 [10] = {
1103 .handler = icmp_discard,
1104 .error = 1,
1105 },
1106 [ICMP_TIME_EXCEEDED] = {
1107 .handler = icmp_unreach,
1108 .error = 1,
1109 },
1110 [ICMP_PARAMETERPROB] = {
1111 .handler = icmp_unreach,
1112 .error = 1,
1113 },
1114 [ICMP_TIMESTAMP] = {
1115 .handler = icmp_timestamp,
1116 },
1117 [ICMP_TIMESTAMPREPLY] = {
1118 .handler = icmp_discard,
1119 },
1120 [ICMP_INFO_REQUEST] = {
1121 .handler = icmp_discard,
1122 },
1123 [ICMP_INFO_REPLY] = {
1124 .handler = icmp_discard,
1125 },
1126 [ICMP_ADDRESS] = {
1127 .handler = icmp_address,
1128 },
1129 [ICMP_ADDRESSREPLY] = {
1130 .handler = icmp_address_reply,
1131 },
1132};
1133
1134static void __net_exit icmp_sk_exit(struct net *net)
1135{
1136 int i;
1137
1138 for_each_possible_cpu(i)
1139 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1140 kfree(net->ipv4.icmp_sk);
1141 net->ipv4.icmp_sk = NULL;
1142}
1143
1144static int __net_init icmp_sk_init(struct net *net)
1145{
1146 int i, err;
1147
1148 net->ipv4.icmp_sk =
1149 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1150 if (net->ipv4.icmp_sk == NULL)
1151 return -ENOMEM;
1152
1153 for_each_possible_cpu(i) {
1154 struct sock *sk;
1155
1156 err = inet_ctl_sock_create(&sk, PF_INET,
1157 SOCK_RAW, IPPROTO_ICMP, net);
1158 if (err < 0)
1159 goto fail;
1160
1161 net->ipv4.icmp_sk[i] = sk;
1162
1163 /* Enough space for 2 64K ICMP packets, including
1164 * sk_buff struct overhead.
1165 */
1166 sk->sk_sndbuf =
1167 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1168
1169 /*
1170 * Speedup sock_wfree()
1171 */
1172 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1173 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1174 }
1175
1176 /* Control parameters for ECHO replies. */
1177 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1178 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1179
1180 /* Control parameter - ignore bogus broadcast responses? */
1181 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1182
1183 /*
1184 * Configurable global rate limit.
1185 *
1186 * ratelimit defines tokens/packet consumed for dst->rate_token
1187 * bucket ratemask defines which icmp types are ratelimited by
1188 * setting it's bit position.
1189 *
1190 * default:
1191 * dest unreachable (3), source quench (4),
1192 * time exceeded (11), parameter problem (12)
1193 */
1194
1195 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1196 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1197 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1198
1199 return 0;
1200
1201fail:
1202 for_each_possible_cpu(i)
1203 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1204 kfree(net->ipv4.icmp_sk);
1205 return err;
1206}
1207
1208static struct pernet_operations __net_initdata icmp_sk_ops = {
1209 .init = icmp_sk_init,
1210 .exit = icmp_sk_exit,
1211};
1212
1213int __init icmp_init(void)
1214{
1215 return register_pernet_subsys(&icmp_sk_ops);
1216}
1217
1218EXPORT_SYMBOL(icmp_err_convert);
1219EXPORT_SYMBOL(icmp_send);
1220EXPORT_SYMBOL(xrlim_allow);
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