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1da177e4
LT		 1/*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@redhat.com>
5 *
6 * Version: $Id: icmp.c,v 1.85 2002/02/01 22:01:03 davem Exp $
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 *
13 * Some of the function names and the icmp unreach table for this
14 * module were derived from [icmp.c 1.0.11 06/02/93] by
15 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
16 * Other than that this module is a complete rewrite.
17 *
18 * Fixes:
19 * Clemens Fruhwirth : introduce global icmp rate limiting
20 * with icmp type masking ability instead
21 * of broken per type icmp timeouts.
22 * Mike Shaver : RFC1122 checks.
23 * Alan Cox : Multicast ping reply as self.
24 * Alan Cox : Fix atomicity lockup in ip_build_xmit
25 * call.
26 * Alan Cox : Added 216,128 byte paths to the MTU
27 * code.
28 * Martin Mares : RFC1812 checks.
29 * Martin Mares : Can be configured to follow redirects
30 * if acting as a router _without_ a
31 * routing protocol (RFC 1812).
32 * Martin Mares : Echo requests may be configured to
33 * be ignored (RFC 1812).
34 * Martin Mares : Limitation of ICMP error message
35 * transmit rate (RFC 1812).
36 * Martin Mares : TOS and Precedence set correctly
37 * (RFC 1812).
38 * Martin Mares : Now copying as much data from the
39 * original packet as we can without
40 * exceeding 576 bytes (RFC 1812).
41 * Willy Konynenberg : Transparent proxying support.
42 * Keith Owens : RFC1191 correction for 4.2BSD based
43 * path MTU bug.
44 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
45 * valid (RFC 1812).
46 * Andi Kleen : Check all packet lengths properly
47 * and moved all kfree_skb() up to
48 * icmp_rcv.
49 * Andi Kleen : Move the rate limit bookkeeping
50 * into the dest entry and use a token
51 * bucket filter (thanks to ANK). Make
52 * the rates sysctl configurable.
53 * Yu Tianli : Fixed two ugly bugs in icmp_send
54 * - IP option length was accounted wrongly
55 * - ICMP header length was not accounted
56 * at all.
57 * Tristan Greaves : Added sysctl option to ignore bogus
58 * broadcast responses from broken routers.
59 *
60 * To Fix:
61 *
62 * - Should use skb_pull() instead of all the manual checking.
63 * This would also greatly simply some upper layer error handlers. --AK
64 *
65 */
66
67#include <linux/config.h>
68#include <linux/module.h>
69#include <linux/types.h>
70#include <linux/jiffies.h>
71#include <linux/kernel.h>
72#include <linux/fcntl.h>
73#include <linux/socket.h>
74#include <linux/in.h>
75#include <linux/inet.h>
76#include <linux/netdevice.h>
77#include <linux/string.h>
78#include <linux/netfilter_ipv4.h>
79#include <net/snmp.h>
80#include <net/ip.h>
81#include <net/route.h>
82#include <net/protocol.h>
83#include <net/icmp.h>
84#include <net/tcp.h>
85#include <net/udp.h>
86#include <net/raw.h>
87#include <linux/skbuff.h>
88#include <net/sock.h>
89#include <linux/errno.h>
90#include <linux/timer.h>
91#include <linux/init.h>
92#include <asm/system.h>
93#include <asm/uaccess.h>
94#include <net/checksum.h>
95
96/*
97 * Build xmit assembly blocks
98 */
99
100struct icmp_bxm {
101 struct sk_buff *skb;
102 int offset;
103 int data_len;
104
105 struct {
106 struct icmphdr icmph;
107 __u32 times[3];
108 } data;
109 int head_len;
110 struct ip_options replyopts;
111 unsigned char optbuf[40];
112};
113
114/*
115 * Statistics
116 */
117DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics);
118
119/* An array of errno for error messages from dest unreach. */
120/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
121
122struct icmp_err icmp_err_convert[] = {
123 {
124 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
125 .fatal = 0,
126 },
127 {
128 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
129 .fatal = 0,
130 },
131 {
132 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
133 .fatal = 1,
134 },
135 {
136 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
137 .fatal = 1,
138 },
139 {
140 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
141 .fatal = 0,
142 },
143 {
144 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
145 .fatal = 0,
146 },
147 {
148 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
149 .fatal = 1,
150 },
151 {
152 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
153 .fatal = 1,
154 },
155 {
156 .errno = ENONET, /* ICMP_HOST_ISOLATED */
157 .fatal = 1,
158 },
159 {
160 .errno = ENETUNREACH, /* ICMP_NET_ANO */
161 .fatal = 1,
162 },
163 {
164 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
165 .fatal = 1,
166 },
167 {
168 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
169 .fatal = 0,
170 },
171 {
172 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
173 .fatal = 0,
174 },
175 {
176 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
177 .fatal = 1,
178 },
179 {
180 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
181 .fatal = 1,
182 },
183 {
184 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
185 .fatal = 1,
186 },
187};
188
189/* Control parameters for ECHO replies. */
190int sysctl_icmp_echo_ignore_all;
191int sysctl_icmp_echo_ignore_broadcasts;
192
193/* Control parameter - ignore bogus broadcast responses? */
194int sysctl_icmp_ignore_bogus_error_responses;
195
196/*
197 * Configurable global rate limit.
198 *
199 * ratelimit defines tokens/packet consumed for dst->rate_token bucket
200 * ratemask defines which icmp types are ratelimited by setting
201 * it's bit position.
202 *
203 * default:
204 * dest unreachable (3), source quench (4),
205 * time exceeded (11), parameter problem (12)
206 */
207
208int sysctl_icmp_ratelimit = 1 * HZ;
209int sysctl_icmp_ratemask = 0x1818;
1c2fb7f9 210int sysctl_icmp_errors_use_inbound_ifaddr;
1da177e4
LT		 211
212/*
213 * ICMP control array. This specifies what to do with each ICMP.
214 */
215
216struct icmp_control {
217 int output_entry; /* Field for increment on output */
218 int input_entry; /* Field for increment on input */
219 void (*handler)(struct sk_buff *skb);
220 short error; /* This ICMP is classed as an error message */
221};
222
223static struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
224
225/*
226 * The ICMP socket(s). This is the most convenient way to flow control
227 * our ICMP output as well as maintain a clean interface throughout
228 * all layers. All Socketless IP sends will soon be gone.
229 *
230 * On SMP we have one ICMP socket per-cpu.
231 */
232static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
233#define icmp_socket __get_cpu_var(__icmp_socket)
234
235static __inline__ int icmp_xmit_lock(void)
236{
237 local_bh_disable();
238
239 if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
240 /* This can happen if the output path signals a
241 * dst_link_failure() for an outgoing ICMP packet.
242 */
243 local_bh_enable();
244 return 1;
245 }
246 return 0;
247}
248
249static void icmp_xmit_unlock(void)
250{
251 spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
252}
253
254/*
255 * Send an ICMP frame.
256 */
257
258/*
259 * Check transmit rate limitation for given message.
260 * The rate information is held in the destination cache now.
261 * This function is generic and could be used for other purposes
262 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
263 *
264 * Note that the same dst_entry fields are modified by functions in
265 * route.c too, but these work for packet destinations while xrlim_allow
266 * works for icmp destinations. This means the rate limiting information
267 * for one "ip object" is shared - and these ICMPs are twice limited:
268 * by source and by destination.
269 *
270 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
271 * SHOULD allow setting of rate limits
272 *
273 * Shared between ICMPv4 and ICMPv6.
274 */
275#define XRLIM_BURST_FACTOR 6
276int xrlim_allow(struct dst_entry *dst, int timeout)
277{
278 unsigned long now;
279 int rc = 0;
280
281 now = jiffies;
282 dst->rate_tokens += now - dst->rate_last;
283 dst->rate_last = now;
284 if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
285 dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
286 if (dst->rate_tokens >= timeout) {
287 dst->rate_tokens -= timeout;
288 rc = 1;
289 }
290 return rc;
291}
292
293static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
294{
295 struct dst_entry *dst = &rt->u.dst;
296 int rc = 1;
297
298 if (type > NR_ICMP_TYPES)
299 goto out;
300
301 /* Don't limit PMTU discovery. */
302 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
303 goto out;
304
305 /* No rate limit on loopback */
306 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
307 goto out;
308
309 /* Limit if icmp type is enabled in ratemask. */
310 if ((1 << type) & sysctl_icmp_ratemask)
311 rc = xrlim_allow(dst, sysctl_icmp_ratelimit);
312out:
313 return rc;
314}
315
316/*
317 * Maintain the counters used in the SNMP statistics for outgoing ICMP
318 */
319static void icmp_out_count(int type)
320{
321 if (type <= NR_ICMP_TYPES) {
322 ICMP_INC_STATS(icmp_pointers[type].output_entry);
323 ICMP_INC_STATS(ICMP_MIB_OUTMSGS);
324 }
325}
326
327/*
328 * Checksum each fragment, and on the first include the headers and final
329 * checksum.
330 */
331static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
332 struct sk_buff *skb)
333{
334 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
335 unsigned int csum;
336
337 csum = skb_copy_and_csum_bits(icmp_param->skb,
338 icmp_param->offset + offset,
339 to, len, 0);
340
341 skb->csum = csum_block_add(skb->csum, csum, odd);
342 if (icmp_pointers[icmp_param->data.icmph.type].error)
343 nf_ct_attach(skb, icmp_param->skb);
344 return 0;
345}
346
347static void icmp_push_reply(struct icmp_bxm *icmp_param,
348 struct ipcm_cookie *ipc, struct rtable *rt)
349{
350 struct sk_buff *skb;
351
352 ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param,
353 icmp_param->data_len+icmp_param->head_len,
354 icmp_param->head_len,
355 ipc, rt, MSG_DONTWAIT);
356
357 if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
358 struct icmphdr *icmph = skb->h.icmph;
359 unsigned int csum = 0;
360 struct sk_buff *skb1;
361
362 skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) {
363 csum = csum_add(csum, skb1->csum);
364 }
365 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
366 (char *)icmph,
367 icmp_param->head_len, csum);
368 icmph->checksum = csum_fold(csum);
369 skb->ip_summed = CHECKSUM_NONE;
370 ip_push_pending_frames(icmp_socket->sk);
371 }
372}
373
374/*
375 * Driving logic for building and sending ICMP messages.
376 */
377
378static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
379{
380 struct sock *sk = icmp_socket->sk;
381 struct inet_sock *inet = inet_sk(sk);
382 struct ipcm_cookie ipc;
383 struct rtable *rt = (struct rtable *)skb->dst;
384 u32 daddr;
385
386 if (ip_options_echo(&icmp_param->replyopts, skb))
387 goto out;
388
389 if (icmp_xmit_lock())
390 return;
391
392 icmp_param->data.icmph.checksum = 0;
393 icmp_out_count(icmp_param->data.icmph.type);
394
395 inet->tos = skb->nh.iph->tos;
396 daddr = ipc.addr = rt->rt_src;
397 ipc.opt = NULL;
398 if (icmp_param->replyopts.optlen) {
399 ipc.opt = &icmp_param->replyopts;
400 if (ipc.opt->srr)
401 daddr = icmp_param->replyopts.faddr;
402 }
403 {
404 struct flowi fl = { .nl_u = { .ip4_u =
405 { .daddr = daddr,
406 .saddr = rt->rt_spec_dst,
407 .tos = RT_TOS(skb->nh.iph->tos) } },
408 .proto = IPPROTO_ICMP };
409 if (ip_route_output_key(&rt, &fl))
410 goto out_unlock;
411 }
412 if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
413 icmp_param->data.icmph.code))
414 icmp_push_reply(icmp_param, &ipc, rt);
415 ip_rt_put(rt);
416out_unlock:
417 icmp_xmit_unlock();
418out:;
419}
420
421
422/*
423 * Send an ICMP message in response to a situation
424 *
425 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
426 * MAY send more (we do).
427 * MUST NOT change this header information.
428 * MUST NOT reply to a multicast/broadcast IP address.
429 * MUST NOT reply to a multicast/broadcast MAC address.
430 * MUST reply to only the first fragment.
431 */
432
433void icmp_send(struct sk_buff *skb_in, int type, int code, u32 info)
434{
435 struct iphdr *iph;
436 int room;
437 struct icmp_bxm icmp_param;
438 struct rtable *rt = (struct rtable *)skb_in->dst;
439 struct ipcm_cookie ipc;
440 u32 saddr;
441 u8 tos;
442
443 if (!rt)
444 goto out;
445
446 /*
447 * Find the original header. It is expected to be valid, of course.
448 * Check this, icmp_send is called from the most obscure devices
449 * sometimes.
450 */
451 iph = skb_in->nh.iph;
452
453 if ((u8 *)iph < skb_in->head || (u8 *)(iph + 1) > skb_in->tail)
454 goto out;
455
456 /*
457 * No replies to physical multicast/broadcast
458 */
459 if (skb_in->pkt_type != PACKET_HOST)
460 goto out;
461
462 /*
463 * Now check at the protocol level
464 */
465 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
466 goto out;
467
468 /*
469 * Only reply to fragment 0. We byte re-order the constant
470 * mask for efficiency.
471 */
472 if (iph->frag_off & htons(IP_OFFSET))
473 goto out;
474
475 /*
476 * If we send an ICMP error to an ICMP error a mess would result..
477 */
478 if (icmp_pointers[type].error) {
479 /*
480 * We are an error, check if we are replying to an
481 * ICMP error
482 */
483 if (iph->protocol == IPPROTO_ICMP) {
484 u8 _inner_type, *itp;
485
486 itp = skb_header_pointer(skb_in,
487 skb_in->nh.raw +
488 (iph->ihl << 2) +
489 offsetof(struct icmphdr,
490 type) -
491 skb_in->data,
492 sizeof(_inner_type),
493 &_inner_type);
494 if (itp == NULL)
495 goto out;
496
497 /*
498 * Assume any unknown ICMP type is an error. This
499 * isn't specified by the RFC, but think about it..
500 */
501 if (*itp > NR_ICMP_TYPES ||
502 icmp_pointers[*itp].error)
503 goto out;
504 }
505 }
506
507 if (icmp_xmit_lock())
508 return;
509
510 /*
511 * Construct source address and options.
512 */
513
514 saddr = iph->daddr;
1c2fb7f9
S		 515 if (!(rt->rt_flags & RTCF_LOCAL)) {
516 if (sysctl_icmp_errors_use_inbound_ifaddr)
517 saddr = inet_select_addr(skb_in->dev, 0, RT_SCOPE_LINK);
518 else
519 saddr = 0;
520 }
1da177e4
LT		 521
522 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
523 IPTOS_PREC_INTERNETCONTROL) :
524 iph->tos;
525
526 if (ip_options_echo(&icmp_param.replyopts, skb_in))
527 goto ende;
528
529
530 /*
531 * Prepare data for ICMP header.
532 */
533
534 icmp_param.data.icmph.type = type;
535 icmp_param.data.icmph.code = code;
536 icmp_param.data.icmph.un.gateway = info;
537 icmp_param.data.icmph.checksum = 0;
538 icmp_param.skb = skb_in;
539 icmp_param.offset = skb_in->nh.raw - skb_in->data;
540 icmp_out_count(icmp_param.data.icmph.type);
541 inet_sk(icmp_socket->sk)->tos = tos;
542 ipc.addr = iph->saddr;
543 ipc.opt = &icmp_param.replyopts;
544
545 {
546 struct flowi fl = {
547 .nl_u = {
548 .ip4_u = {
549 .daddr = icmp_param.replyopts.srr ?
550 icmp_param.replyopts.faddr :
551 iph->saddr,
552 .saddr = saddr,
553 .tos = RT_TOS(tos)
554 }
555 },
556 .proto = IPPROTO_ICMP,
557 .uli_u = {
558 .icmpt = {
559 .type = type,
560 .code = code
561 }
562 }
563 };
564 if (ip_route_output_key(&rt, &fl))
565 goto out_unlock;
566 }
567
568 if (!icmpv4_xrlim_allow(rt, type, code))
569 goto ende;
570
571 /* RFC says return as much as we can without exceeding 576 bytes. */
572
573 room = dst_mtu(&rt->u.dst);
574 if (room > 576)
575 room = 576;
576 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
577 room -= sizeof(struct icmphdr);
578
579 icmp_param.data_len = skb_in->len - icmp_param.offset;
580 if (icmp_param.data_len > room)
581 icmp_param.data_len = room;
582 icmp_param.head_len = sizeof(struct icmphdr);
583
584 icmp_push_reply(&icmp_param, &ipc, rt);
585ende:
586 ip_rt_put(rt);
587out_unlock:
588 icmp_xmit_unlock();
589out:;
590}
591
592
593/*
594 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
595 */
596
597static void icmp_unreach(struct sk_buff *skb)
598{
599 struct iphdr *iph;
600 struct icmphdr *icmph;
601 int hash, protocol;
602 struct net_protocol *ipprot;
603 struct sock *raw_sk;
604 u32 info = 0;
605
606 /*
607 * Incomplete header ?
608 * Only checks for the IP header, there should be an
609 * additional check for longer headers in upper levels.
610 */
611
612 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
613 goto out_err;
614
615 icmph = skb->h.icmph;
616 iph = (struct iphdr *)skb->data;
617
618 if (iph->ihl < 5) /* Mangled header, drop. */
619 goto out_err;
620
621 if (icmph->type == ICMP_DEST_UNREACH) {
622 switch (icmph->code & 15) {
623 case ICMP_NET_UNREACH:
624 case ICMP_HOST_UNREACH:
625 case ICMP_PROT_UNREACH:
626 case ICMP_PORT_UNREACH:
627 break;
628 case ICMP_FRAG_NEEDED:
629 if (ipv4_config.no_pmtu_disc) {
630 LIMIT_NETDEBUG(
631 printk(KERN_INFO "ICMP: %u.%u.%u.%u: "
632 "fragmentation needed "
633 "and DF set.\n",
634 NIPQUAD(iph->daddr)));
635 } else {
636 info = ip_rt_frag_needed(iph,
637 ntohs(icmph->un.frag.mtu));
638 if (!info)
639 goto out;
640 }
641 break;
642 case ICMP_SR_FAILED:
643 LIMIT_NETDEBUG(
644 printk(KERN_INFO "ICMP: %u.%u.%u.%u: Source "
645 "Route Failed.\n",
646 NIPQUAD(iph->daddr)));
647 break;
648 default:
649 break;
650 }
651 if (icmph->code > NR_ICMP_UNREACH)
652 goto out;
653 } else if (icmph->type == ICMP_PARAMETERPROB)
654 info = ntohl(icmph->un.gateway) >> 24;
655
656 /*
657 * Throw it at our lower layers
658 *
659 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
660 * header.
661 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
662 * transport layer.
663 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
664 * transport layer.
665 */
666
667 /*
668 * Check the other end isnt violating RFC 1122. Some routers send
669 * bogus responses to broadcast frames. If you see this message
670 * first check your netmask matches at both ends, if it does then
671 * get the other vendor to fix their kit.
672 */
673
674 if (!sysctl_icmp_ignore_bogus_error_responses &&
675 inet_addr_type(iph->daddr) == RTN_BROADCAST) {
676 if (net_ratelimit())
677 printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP "
678 "type %u, code %u "
679 "error to a broadcast: %u.%u.%u.%u on %s\n",
680 NIPQUAD(skb->nh.iph->saddr),
681 icmph->type, icmph->code,
682 NIPQUAD(iph->daddr),
683 skb->dev->name);
684 goto out;
685 }
686
687 /* Checkin full IP header plus 8 bytes of protocol to
688 * avoid additional coding at protocol handlers.
689 */
690 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
691 goto out;
692
693 iph = (struct iphdr *)skb->data;
694 protocol = iph->protocol;
695
696 /*
697 * Deliver ICMP message to raw sockets. Pretty useless feature?
698 */
699
700 /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
701 hash = protocol & (MAX_INET_PROTOS - 1);
702 read_lock(&raw_v4_lock);
703 if ((raw_sk = sk_head(&raw_v4_htable[hash])) != NULL) {
704 while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr,
705 iph->saddr,
706 skb->dev->ifindex)) != NULL) {
707 raw_err(raw_sk, skb, info);
708 raw_sk = sk_next(raw_sk);
709 iph = (struct iphdr *)skb->data;
710 }
711 }
712 read_unlock(&raw_v4_lock);
713
714 rcu_read_lock();
715 ipprot = rcu_dereference(inet_protos[hash]);
716 if (ipprot && ipprot->err_handler)
717 ipprot->err_handler(skb, info);
718 rcu_read_unlock();
719
720out:
721 return;
722out_err:
723 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
724 goto out;
725}
726
727
728/*
729 * Handle ICMP_REDIRECT.
730 */
731
732static void icmp_redirect(struct sk_buff *skb)
733{
734 struct iphdr *iph;
735 unsigned long ip;
736
737 if (skb->len < sizeof(struct iphdr))
738 goto out_err;
739
740 /*
741 * Get the copied header of the packet that caused the redirect
742 */
743 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
744 goto out;
745
746 iph = (struct iphdr *)skb->data;
747 ip = iph->daddr;
748
749 switch (skb->h.icmph->code & 7) {
750 case ICMP_REDIR_NET:
751 case ICMP_REDIR_NETTOS:
752 /*
753 * As per RFC recommendations now handle it as a host redirect.
754 */
755 case ICMP_REDIR_HOST:
756 case ICMP_REDIR_HOSTTOS:
757 ip_rt_redirect(skb->nh.iph->saddr, ip, skb->h.icmph->un.gateway,
758 iph->saddr, iph->tos, skb->dev);
759 break;
760 }
761out:
762 return;
763out_err:
764 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
765 goto out;
766}
767
768/*
769 * Handle ICMP_ECHO ("ping") requests.
770 *
771 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
772 * requests.
773 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
774 * included in the reply.
775 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
776 * echo requests, MUST have default=NOT.
777 * See also WRT handling of options once they are done and working.
778 */
779
780static void icmp_echo(struct sk_buff *skb)
781{
782 if (!sysctl_icmp_echo_ignore_all) {
783 struct icmp_bxm icmp_param;
784
785 icmp_param.data.icmph = *skb->h.icmph;
786 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
787 icmp_param.skb = skb;
788 icmp_param.offset = 0;
789 icmp_param.data_len = skb->len;
790 icmp_param.head_len = sizeof(struct icmphdr);
791 icmp_reply(&icmp_param, skb);
792 }
793}
794
795/*
796 * Handle ICMP Timestamp requests.
797 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
798 * SHOULD be in the kernel for minimum random latency.
799 * MUST be accurate to a few minutes.
800 * MUST be updated at least at 15Hz.
801 */
802static void icmp_timestamp(struct sk_buff *skb)
803{
804 struct timeval tv;
805 struct icmp_bxm icmp_param;
806 /*
807 * Too short.
808 */
809 if (skb->len < 4)
810 goto out_err;
811
812 /*
813 * Fill in the current time as ms since midnight UT:
814 */
815 do_gettimeofday(&tv);
816 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 +
817 tv.tv_usec / 1000);
818 icmp_param.data.times[2] = icmp_param.data.times[1];
819 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
820 BUG();
821 icmp_param.data.icmph = *skb->h.icmph;
822 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
823 icmp_param.data.icmph.code = 0;
824 icmp_param.skb = skb;
825 icmp_param.offset = 0;
826 icmp_param.data_len = 0;
827 icmp_param.head_len = sizeof(struct icmphdr) + 12;
828 icmp_reply(&icmp_param, skb);
829out:
830 return;
831out_err:
832 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
833 goto out;
834}
835
836
837/*
838 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
839 *
840 * RFC1122 (3.2.2.9). A host MUST only send replies to
841 * ADDRESS_MASK requests if it's been configured as an address mask
842 * agent. Receiving a request doesn't constitute implicit permission to
843 * act as one. Of course, implementing this correctly requires (SHOULD)
844 * a way to turn the functionality on and off. Another one for sysctl(),
845 * I guess. -- MS
846 *
847 * RFC1812 (4.3.3.9). A router MUST implement it.
848 * A router SHOULD have switch turning it on/off.
849 * This switch MUST be ON by default.
850 *
851 * Gratuitous replies, zero-source replies are not implemented,
852 * that complies with RFC. DO NOT implement them!!! All the idea
853 * of broadcast addrmask replies as specified in RFC950 is broken.
854 * The problem is that it is not uncommon to have several prefixes
855 * on one physical interface. Moreover, addrmask agent can even be
856 * not aware of existing another prefixes.
857 * If source is zero, addrmask agent cannot choose correct prefix.
858 * Gratuitous mask announcements suffer from the same problem.
859 * RFC1812 explains it, but still allows to use ADDRMASK,
860 * that is pretty silly. --ANK
861 *
862 * All these rules are so bizarre, that I removed kernel addrmask
863 * support at all. It is wrong, it is obsolete, nobody uses it in
864 * any case. --ANK
865 *
866 * Furthermore you can do it with a usermode address agent program
867 * anyway...
868 */
869
870static void icmp_address(struct sk_buff *skb)
871{
872#if 0
873 if (net_ratelimit())
874 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
875#endif
876}
877
878/*
879 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
880 * loudly if an inconsistency is found.
881 */
882
883static void icmp_address_reply(struct sk_buff *skb)
884{
885 struct rtable *rt = (struct rtable *)skb->dst;
886 struct net_device *dev = skb->dev;
887 struct in_device *in_dev;
888 struct in_ifaddr *ifa;
889
890 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
891 goto out;
892
893 in_dev = in_dev_get(dev);
894 if (!in_dev)
895 goto out;
896 rcu_read_lock();
897 if (in_dev->ifa_list &&
898 IN_DEV_LOG_MARTIANS(in_dev) &&
899 IN_DEV_FORWARD(in_dev)) {
900 u32 _mask, *mp;
901
902 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
903 if (mp == NULL)
904 BUG();
905 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
906 if (*mp == ifa->ifa_mask &&
907 inet_ifa_match(rt->rt_src, ifa))
908 break;
909 }
910 if (!ifa && net_ratelimit()) {
911 printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
912 "%s/%u.%u.%u.%u\n",
913 NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
914 }
915 }
916 rcu_read_unlock();
917 in_dev_put(in_dev);
918out:;
919}
920
921static void icmp_discard(struct sk_buff *skb)
922{
923}
924
925/*
926 * Deal with incoming ICMP packets.
927 */
928int icmp_rcv(struct sk_buff *skb)
929{
930 struct icmphdr *icmph;
931 struct rtable *rt = (struct rtable *)skb->dst;
932
933 ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
934
935 switch (skb->ip_summed) {
936 case CHECKSUM_HW:
937 if (!(u16)csum_fold(skb->csum))
938 break;
939 NETDEBUG(if (net_ratelimit())
940 printk(KERN_DEBUG "icmp v4 hw csum failure\n"));
941 case CHECKSUM_NONE:
942 if ((u16)csum_fold(skb_checksum(skb, 0, skb->len, 0)))
943 goto error;
944 default:;
945 }
946
947 if (!pskb_pull(skb, sizeof(struct icmphdr)))
948 goto error;
949
950 icmph = skb->h.icmph;
951
952 /*
953 * 18 is the highest 'known' ICMP type. Anything else is a mystery
954 *
955 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
956 * discarded.
957 */
958 if (icmph->type > NR_ICMP_TYPES)
959 goto error;
960
961
962 /*
963 * Parse the ICMP message
964 */
965
966 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
967 /*
968 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
969 * silently ignored (we let user decide with a sysctl).
970 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
971 * discarded if to broadcast/multicast.
972 */
973 if (icmph->type == ICMP_ECHO &&
974 sysctl_icmp_echo_ignore_broadcasts) {
975 goto error;
976 }
977 if (icmph->type != ICMP_ECHO &&
978 icmph->type != ICMP_TIMESTAMP &&
979 icmph->type != ICMP_ADDRESS &&
980 icmph->type != ICMP_ADDRESSREPLY) {
981 goto error;
982 }
983 }
984
985 ICMP_INC_STATS_BH(icmp_pointers[icmph->type].input_entry);
986 icmp_pointers[icmph->type].handler(skb);
987
988drop:
989 kfree_skb(skb);
990 return 0;
991error:
992 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
993 goto drop;
994}
995
996/*
997 * This table is the definition of how we handle ICMP.
998 */
999static struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1000 [ICMP_ECHOREPLY] = {
1001 .output_entry = ICMP_MIB_OUTECHOREPS,
1002 .input_entry = ICMP_MIB_INECHOREPS,
1003 .handler = icmp_discard,
1004 },
1005 [1] = {
1006 .output_entry = ICMP_MIB_DUMMY,
1007 .input_entry = ICMP_MIB_INERRORS,
1008 .handler = icmp_discard,
1009 .error = 1,
1010 },
1011 [2] = {
1012 .output_entry = ICMP_MIB_DUMMY,
1013 .input_entry = ICMP_MIB_INERRORS,
1014 .handler = icmp_discard,
1015 .error = 1,
1016 },
1017 [ICMP_DEST_UNREACH] = {
1018 .output_entry = ICMP_MIB_OUTDESTUNREACHS,
1019 .input_entry = ICMP_MIB_INDESTUNREACHS,
1020 .handler = icmp_unreach,
1021 .error = 1,
1022 },
1023 [ICMP_SOURCE_QUENCH] = {
1024 .output_entry = ICMP_MIB_OUTSRCQUENCHS,
1025 .input_entry = ICMP_MIB_INSRCQUENCHS,
1026 .handler = icmp_unreach,
1027 .error = 1,
1028 },
1029 [ICMP_REDIRECT] = {
1030 .output_entry = ICMP_MIB_OUTREDIRECTS,
1031 .input_entry = ICMP_MIB_INREDIRECTS,
1032 .handler = icmp_redirect,
1033 .error = 1,
1034 },
1035 [6] = {
1036 .output_entry = ICMP_MIB_DUMMY,
1037 .input_entry = ICMP_MIB_INERRORS,
1038 .handler = icmp_discard,
1039 .error = 1,
1040 },
1041 [7] = {
1042 .output_entry = ICMP_MIB_DUMMY,
1043 .input_entry = ICMP_MIB_INERRORS,
1044 .handler = icmp_discard,
1045 .error = 1,
1046 },
1047 [ICMP_ECHO] = {
1048 .output_entry = ICMP_MIB_OUTECHOS,
1049 .input_entry = ICMP_MIB_INECHOS,
1050 .handler = icmp_echo,
1051 },
1052 [9] = {
1053 .output_entry = ICMP_MIB_DUMMY,
1054 .input_entry = ICMP_MIB_INERRORS,
1055 .handler = icmp_discard,
1056 .error = 1,
1057 },
1058 [10] = {
1059 .output_entry = ICMP_MIB_DUMMY,
1060 .input_entry = ICMP_MIB_INERRORS,
1061 .handler = icmp_discard,
1062 .error = 1,
1063 },
1064 [ICMP_TIME_EXCEEDED] = {
1065 .output_entry = ICMP_MIB_OUTTIMEEXCDS,
1066 .input_entry = ICMP_MIB_INTIMEEXCDS,
1067 .handler = icmp_unreach,
1068 .error = 1,
1069 },
1070 [ICMP_PARAMETERPROB] = {
1071 .output_entry = ICMP_MIB_OUTPARMPROBS,
1072 .input_entry = ICMP_MIB_INPARMPROBS,
1073 .handler = icmp_unreach,
1074 .error = 1,
1075 },
1076 [ICMP_TIMESTAMP] = {
1077 .output_entry = ICMP_MIB_OUTTIMESTAMPS,
1078 .input_entry = ICMP_MIB_INTIMESTAMPS,
1079 .handler = icmp_timestamp,
1080 },
1081 [ICMP_TIMESTAMPREPLY] = {
1082 .output_entry = ICMP_MIB_OUTTIMESTAMPREPS,
1083 .input_entry = ICMP_MIB_INTIMESTAMPREPS,
1084 .handler = icmp_discard,
1085 },
1086 [ICMP_INFO_REQUEST] = {
1087 .output_entry = ICMP_MIB_DUMMY,
1088 .input_entry = ICMP_MIB_DUMMY,
1089 .handler = icmp_discard,
1090 },
1091 [ICMP_INFO_REPLY] = {
1092 .output_entry = ICMP_MIB_DUMMY,
1093 .input_entry = ICMP_MIB_DUMMY,
1094 .handler = icmp_discard,
1095 },
1096 [ICMP_ADDRESS] = {
1097 .output_entry = ICMP_MIB_OUTADDRMASKS,
1098 .input_entry = ICMP_MIB_INADDRMASKS,
1099 .handler = icmp_address,
1100 },
1101 [ICMP_ADDRESSREPLY] = {
1102 .output_entry = ICMP_MIB_OUTADDRMASKREPS,
1103 .input_entry = ICMP_MIB_INADDRMASKREPS,
1104 .handler = icmp_address_reply,
1105 },
1106};
1107
1108void __init icmp_init(struct net_proto_family *ops)
1109{
1110 struct inet_sock *inet;
1111 int i;
1112
1113 for (i = 0; i < NR_CPUS; i++) {
1114 int err;
1115
1116 if (!cpu_possible(i))
1117 continue;
1118
1119 err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
1120 &per_cpu(__icmp_socket, i));
1121
1122 if (err < 0)
1123 panic("Failed to create the ICMP control socket.\n");
1124
1125 per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
1126
1127 /* Enough space for 2 64K ICMP packets, including
1128 * sk_buff struct overhead.
1129 */
1130 per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
1131 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1132
1133 inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
1134 inet->uc_ttl = -1;
1135 inet->pmtudisc = IP_PMTUDISC_DONT;
1136
1137 /* Unhash it so that IP input processing does not even
1138 * see it, we do not wish this socket to see incoming
1139 * packets.
1140 */
1141 per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
1142 }
1143}
1144
1145EXPORT_SYMBOL(icmp_err_convert);
1146EXPORT_SYMBOL(icmp_send);
1147EXPORT_SYMBOL(icmp_statistics);
1148EXPORT_SYMBOL(xrlim_allow);
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