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[net-next-2.6.git] / net / ipv4 / icmp.c
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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
1da177e4
LT		 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>
14c85021 75#include <linux/inetdevice.h>
1da177e4
LT		 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;
b03d73e3 107 __be32 times[3];
1da177e4
LT		 108 } data;
109 int head_len;
110 struct ip_options replyopts;
111 unsigned char optbuf[40];
112};
113
114/*
115 * Statistics
116 */
ba89966c 117DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly;
96793b48 118DEFINE_SNMP_STAT(struct icmpmsg_mib, icmpmsg_statistics) __read_mostly;
1da177e4
LT		 119
120/* An array of errno for error messages from dest unreach. */
121/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
122
123struct icmp_err icmp_err_convert[] = {
124 {
125 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
126 .fatal = 0,
127 },
128 {
129 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
130 .fatal = 0,
131 },
132 {
133 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
134 .fatal = 1,
135 },
136 {
137 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
138 .fatal = 1,
139 },
140 {
141 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
142 .fatal = 0,
143 },
144 {
145 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
146 .fatal = 0,
147 },
148 {
149 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
150 .fatal = 1,
151 },
152 {
153 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
154 .fatal = 1,
155 },
156 {
157 .errno = ENONET, /* ICMP_HOST_ISOLATED */
158 .fatal = 1,
159 },
160 {
161 .errno = ENETUNREACH, /* ICMP_NET_ANO */
162 .fatal = 1,
163 },
164 {
165 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
166 .fatal = 1,
167 },
168 {
169 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
170 .fatal = 0,
171 },
172 {
173 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
174 .fatal = 0,
175 },
176 {
177 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
178 .fatal = 1,
179 },
180 {
181 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
182 .fatal = 1,
183 },
184 {
185 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
186 .fatal = 1,
187 },
188};
189
190/* Control parameters for ECHO replies. */
ab32ea5d
BH		 191int sysctl_icmp_echo_ignore_all __read_mostly;
192int sysctl_icmp_echo_ignore_broadcasts __read_mostly = 1;
1da177e4
LT		 193
194/* Control parameter - ignore bogus broadcast responses? */
ab32ea5d 195int sysctl_icmp_ignore_bogus_error_responses __read_mostly = 1;
1da177e4
LT		 196
197/*
198 * Configurable global rate limit.
199 *
200 * ratelimit defines tokens/packet consumed for dst->rate_token bucket
201 * ratemask defines which icmp types are ratelimited by setting
202 * it's bit position.
203 *
204 * default:
205 * dest unreachable (3), source quench (4),
206 * time exceeded (11), parameter problem (12)
207 */
208
ab32ea5d
BH		 209int sysctl_icmp_ratelimit __read_mostly = 1 * HZ;
210int sysctl_icmp_ratemask __read_mostly = 0x1818;
211int sysctl_icmp_errors_use_inbound_ifaddr __read_mostly;
1da177e4
LT		 212
213/*
214 * ICMP control array. This specifies what to do with each ICMP.
215 */
216
217struct icmp_control {
1da177e4
LT		 218 void (*handler)(struct sk_buff *skb);
219 short error; /* This ICMP is classed as an error message */
220};
221
9b5b5cff 222static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
1da177e4
LT		 223
224/*
225 * The ICMP socket(s). This is the most convenient way to flow control
226 * our ICMP output as well as maintain a clean interface throughout
227 * all layers. All Socketless IP sends will soon be gone.
228 *
229 * On SMP we have one ICMP socket per-cpu.
230 */
231static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
232#define icmp_socket __get_cpu_var(__icmp_socket)
233
234static __inline__ int icmp_xmit_lock(void)
235{
236 local_bh_disable();
237
238 if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
239 /* This can happen if the output path signals a
240 * dst_link_failure() for an outgoing ICMP packet.
241 */
242 local_bh_enable();
243 return 1;
244 }
245 return 0;
246}
247
248static void icmp_xmit_unlock(void)
249{
250 spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
251}
252
253/*
254 * Send an ICMP frame.
255 */
256
257/*
258 * Check transmit rate limitation for given message.
259 * The rate information is held in the destination cache now.
260 * This function is generic and could be used for other purposes
261 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
262 *
263 * Note that the same dst_entry fields are modified by functions in
264 * route.c too, but these work for packet destinations while xrlim_allow
265 * works for icmp destinations. This means the rate limiting information
266 * for one "ip object" is shared - and these ICMPs are twice limited:
267 * by source and by destination.
268 *
269 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
270 * SHOULD allow setting of rate limits
271 *
272 * Shared between ICMPv4 and ICMPv6.
273 */
274#define XRLIM_BURST_FACTOR 6
275int xrlim_allow(struct dst_entry *dst, int timeout)
276{
277 unsigned long now;
278 int rc = 0;
279
280 now = jiffies;
281 dst->rate_tokens += now - dst->rate_last;
282 dst->rate_last = now;
283 if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
284 dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
285 if (dst->rate_tokens >= timeout) {
286 dst->rate_tokens -= timeout;
287 rc = 1;
288 }
289 return rc;
290}
291
292static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
293{
294 struct dst_entry *dst = &rt->u.dst;
295 int rc = 1;
296
297 if (type > NR_ICMP_TYPES)
298 goto out;
299
300 /* Don't limit PMTU discovery. */
301 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
302 goto out;
303
304 /* No rate limit on loopback */
305 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
e905a9ed 306 goto out;
1da177e4
LT		 307
308 /* Limit if icmp type is enabled in ratemask. */
309 if ((1 << type) & sysctl_icmp_ratemask)
310 rc = xrlim_allow(dst, sysctl_icmp_ratelimit);
311out:
312 return rc;
313}
314
315/*
316 * Maintain the counters used in the SNMP statistics for outgoing ICMP
317 */
96793b48 318void icmp_out_count(unsigned char type)
1da177e4 319{
96793b48
DS		 320 ICMPMSGOUT_INC_STATS(type);
321 ICMP_INC_STATS(ICMP_MIB_OUTMSGS);
1da177e4
LT		 322}
323
324/*
325 * Checksum each fragment, and on the first include the headers and final
326 * checksum.
327 */
328static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
329 struct sk_buff *skb)
330{
331 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
5f92a738 332 __wsum csum;
1da177e4
LT		 333
334 csum = skb_copy_and_csum_bits(icmp_param->skb,
335 icmp_param->offset + offset,
336 to, len, 0);
337
338 skb->csum = csum_block_add(skb->csum, csum, odd);
339 if (icmp_pointers[icmp_param->data.icmph.type].error)
340 nf_ct_attach(skb, icmp_param->skb);
341 return 0;
342}
343
344static void icmp_push_reply(struct icmp_bxm *icmp_param,
345 struct ipcm_cookie *ipc, struct rtable *rt)
346{
347 struct sk_buff *skb;
348
cb94c62c 349 if (ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param,
e905a9ed
YH		 350 icmp_param->data_len+icmp_param->head_len,
351 icmp_param->head_len,
352 ipc, rt, MSG_DONTWAIT) < 0)
cb94c62c
PM		 353 ip_flush_pending_frames(icmp_socket->sk);
354 else if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
88c7664f 355 struct icmphdr *icmph = icmp_hdr(skb);
d3bc23e7 356 __wsum csum = 0;
1da177e4
LT		 357 struct sk_buff *skb1;
358
359 skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) {
360 csum = csum_add(csum, skb1->csum);
361 }
362 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
363 (char *)icmph,
364 icmp_param->head_len, csum);
365 icmph->checksum = csum_fold(csum);
366 skb->ip_summed = CHECKSUM_NONE;
367 ip_push_pending_frames(icmp_socket->sk);
368 }
369}
370
371/*
372 * Driving logic for building and sending ICMP messages.
373 */
374
375static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
376{
377 struct sock *sk = icmp_socket->sk;
378 struct inet_sock *inet = inet_sk(sk);
379 struct ipcm_cookie ipc;
380 struct rtable *rt = (struct rtable *)skb->dst;
3ca3c68e 381 __be32 daddr;
1da177e4
LT		 382
383 if (ip_options_echo(&icmp_param->replyopts, skb))
f00c401b 384 return;
1da177e4
LT		 385
386 if (icmp_xmit_lock())
387 return;
388
389 icmp_param->data.icmph.checksum = 0;
1da177e4 390
eddc9ec5 391 inet->tos = ip_hdr(skb)->tos;
1da177e4
LT		 392 daddr = ipc.addr = rt->rt_src;
393 ipc.opt = NULL;
394 if (icmp_param->replyopts.optlen) {
395 ipc.opt = &icmp_param->replyopts;
396 if (ipc.opt->srr)
397 daddr = icmp_param->replyopts.faddr;
398 }
399 {
400 struct flowi fl = { .nl_u = { .ip4_u =
401 { .daddr = daddr,
402 .saddr = rt->rt_spec_dst,
eddc9ec5 403 .tos = RT_TOS(ip_hdr(skb)->tos) } },
1da177e4 404 .proto = IPPROTO_ICMP };
beb8d13b 405 security_skb_classify_flow(skb, &fl);
1da177e4
LT		 406 if (ip_route_output_key(&rt, &fl))
407 goto out_unlock;
408 }
409 if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
410 icmp_param->data.icmph.code))
411 icmp_push_reply(icmp_param, &ipc, rt);
412 ip_rt_put(rt);
413out_unlock:
414 icmp_xmit_unlock();
1da177e4
LT		 415}
416
417
418/*
419 * Send an ICMP message in response to a situation
420 *
421 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
422 * MAY send more (we do).
423 * MUST NOT change this header information.
424 * MUST NOT reply to a multicast/broadcast IP address.
425 * MUST NOT reply to a multicast/broadcast MAC address.
426 * MUST reply to only the first fragment.
427 */
428
e4883014 429void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
1da177e4
LT		 430{
431 struct iphdr *iph;
432 int room;
433 struct icmp_bxm icmp_param;
434 struct rtable *rt = (struct rtable *)skb_in->dst;
435 struct ipcm_cookie ipc;
a61ced5d 436 __be32 saddr;
1da177e4
LT		 437 u8 tos;
438
439 if (!rt)
440 goto out;
441
442 /*
443 * Find the original header. It is expected to be valid, of course.
444 * Check this, icmp_send is called from the most obscure devices
445 * sometimes.
446 */
eddc9ec5 447 iph = ip_hdr(skb_in);
1da177e4 448
27a884dc
ACM		 449 if ((u8 *)iph < skb_in->head ||
450 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
1da177e4
LT		 451 goto out;
452
453 /*
454 * No replies to physical multicast/broadcast
455 */
456 if (skb_in->pkt_type != PACKET_HOST)
457 goto out;
458
459 /*
460 * Now check at the protocol level
461 */
462 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
463 goto out;
464
465 /*
466 * Only reply to fragment 0. We byte re-order the constant
467 * mask for efficiency.
468 */
469 if (iph->frag_off & htons(IP_OFFSET))
470 goto out;
471
472 /*
473 * If we send an ICMP error to an ICMP error a mess would result..
474 */
475 if (icmp_pointers[type].error) {
476 /*
477 * We are an error, check if we are replying to an
478 * ICMP error
479 */
480 if (iph->protocol == IPPROTO_ICMP) {
481 u8 _inner_type, *itp;
482
483 itp = skb_header_pointer(skb_in,
d56f90a7 484 skb_network_header(skb_in) +
1da177e4
LT		 485 (iph->ihl << 2) +
486 offsetof(struct icmphdr,
487 type) -
488 skb_in->data,
489 sizeof(_inner_type),
490 &_inner_type);
491 if (itp == NULL)
492 goto out;
493
494 /*
495 * Assume any unknown ICMP type is an error. This
496 * isn't specified by the RFC, but think about it..
497 */
498 if (*itp > NR_ICMP_TYPES ||
499 icmp_pointers[*itp].error)
500 goto out;
501 }
502 }
503
504 if (icmp_xmit_lock())
505 return;
506
507 /*
508 * Construct source address and options.
509 */
510
511 saddr = iph->daddr;
1c2fb7f9 512 if (!(rt->rt_flags & RTCF_LOCAL)) {
6e1d9103
PM		 513 struct net_device *dev = NULL;
514
515 if (rt->fl.iif && sysctl_icmp_errors_use_inbound_ifaddr)
881d966b 516 dev = dev_get_by_index(&init_net, rt->fl.iif);
6e1d9103
PM		 517
518 if (dev) {
519 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
520 dev_put(dev);
521 } else
1c2fb7f9
S		 522 saddr = 0;
523 }
1da177e4
LT		 524
525 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
526 IPTOS_PREC_INTERNETCONTROL) :
527 iph->tos;
528
529 if (ip_options_echo(&icmp_param.replyopts, skb_in))
fa60cf7f 530 goto out_unlock;
1da177e4
LT		 531
532
533 /*
534 * Prepare data for ICMP header.
535 */
536
537 icmp_param.data.icmph.type = type;
538 icmp_param.data.icmph.code = code;
539 icmp_param.data.icmph.un.gateway = info;
540 icmp_param.data.icmph.checksum = 0;
541 icmp_param.skb = skb_in;
d56f90a7 542 icmp_param.offset = skb_network_offset(skb_in);
1da177e4
LT		 543 inet_sk(icmp_socket->sk)->tos = tos;
544 ipc.addr = iph->saddr;
545 ipc.opt = &icmp_param.replyopts;
546
547 {
548 struct flowi fl = {
549 .nl_u = {
550 .ip4_u = {
551 .daddr = icmp_param.replyopts.srr ?
552 icmp_param.replyopts.faddr :
553 iph->saddr,
554 .saddr = saddr,
555 .tos = RT_TOS(tos)
556 }
557 },
558 .proto = IPPROTO_ICMP,
559 .uli_u = {
560 .icmpt = {
561 .type = type,
562 .code = code
563 }
564 }
565 };
beb8d13b 566 security_skb_classify_flow(skb_in, &fl);
1da177e4
LT		 567 if (ip_route_output_key(&rt, &fl))
568 goto out_unlock;
569 }
570
571 if (!icmpv4_xrlim_allow(rt, type, code))
572 goto ende;
573
574 /* RFC says return as much as we can without exceeding 576 bytes. */
575
576 room = dst_mtu(&rt->u.dst);
577 if (room > 576)
578 room = 576;
579 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
580 room -= sizeof(struct icmphdr);
581
582 icmp_param.data_len = skb_in->len - icmp_param.offset;
583 if (icmp_param.data_len > room)
584 icmp_param.data_len = room;
585 icmp_param.head_len = sizeof(struct icmphdr);
586
587 icmp_push_reply(&icmp_param, &ipc, rt);
588ende:
589 ip_rt_put(rt);
590out_unlock:
591 icmp_xmit_unlock();
592out:;
593}
594
595
596/*
597 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
598 */
599
600static void icmp_unreach(struct sk_buff *skb)
601{
602 struct iphdr *iph;
603 struct icmphdr *icmph;
604 int hash, protocol;
605 struct net_protocol *ipprot;
606 struct sock *raw_sk;
607 u32 info = 0;
608
609 /*
610 * Incomplete header ?
611 * Only checks for the IP header, there should be an
612 * additional check for longer headers in upper levels.
613 */
614
615 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
616 goto out_err;
617
88c7664f 618 icmph = icmp_hdr(skb);
1da177e4
LT		 619 iph = (struct iphdr *)skb->data;
620
621 if (iph->ihl < 5) /* Mangled header, drop. */
622 goto out_err;
623
624 if (icmph->type == ICMP_DEST_UNREACH) {
625 switch (icmph->code & 15) {
626 case ICMP_NET_UNREACH:
627 case ICMP_HOST_UNREACH:
628 case ICMP_PROT_UNREACH:
629 case ICMP_PORT_UNREACH:
630 break;
631 case ICMP_FRAG_NEEDED:
632 if (ipv4_config.no_pmtu_disc) {
64ce2073 633 LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: "
1da177e4
LT		 634 "fragmentation needed "
635 "and DF set.\n",
64ce2073 636 NIPQUAD(iph->daddr));
1da177e4
LT		 637 } else {
638 info = ip_rt_frag_needed(iph,
639 ntohs(icmph->un.frag.mtu));
640 if (!info)
641 goto out;
642 }
643 break;
644 case ICMP_SR_FAILED:
64ce2073 645 LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: Source "
1da177e4 646 "Route Failed.\n",
64ce2073 647 NIPQUAD(iph->daddr));
1da177e4
LT		 648 break;
649 default:
650 break;
651 }
652 if (icmph->code > NR_ICMP_UNREACH)
653 goto out;
654 } else if (icmph->type == ICMP_PARAMETERPROB)
655 info = ntohl(icmph->un.gateway) >> 24;
656
657 /*
658 * Throw it at our lower layers
659 *
660 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
661 * header.
662 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
663 * transport layer.
664 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
665 * transport layer.
666 */
667
668 /*
669 * Check the other end isnt violating RFC 1122. Some routers send
670 * bogus responses to broadcast frames. If you see this message
671 * first check your netmask matches at both ends, if it does then
672 * get the other vendor to fix their kit.
673 */
674
675 if (!sysctl_icmp_ignore_bogus_error_responses &&
676 inet_addr_type(iph->daddr) == RTN_BROADCAST) {
677 if (net_ratelimit())
678 printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP "
679 "type %u, code %u "
680 "error to a broadcast: %u.%u.%u.%u on %s\n",
eddc9ec5 681 NIPQUAD(ip_hdr(skb)->saddr),
1da177e4
LT		 682 icmph->type, icmph->code,
683 NIPQUAD(iph->daddr),
684 skb->dev->name);
685 goto out;
686 }
687
688 /* Checkin full IP header plus 8 bytes of protocol to
689 * avoid additional coding at protocol handlers.
690 */
691 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
692 goto out;
693
694 iph = (struct iphdr *)skb->data;
695 protocol = iph->protocol;
696
697 /*
698 * Deliver ICMP message to raw sockets. Pretty useless feature?
699 */
700
701 /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
702 hash = protocol & (MAX_INET_PROTOS - 1);
703 read_lock(&raw_v4_lock);
704 if ((raw_sk = sk_head(&raw_v4_htable[hash])) != NULL) {
705 while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr,
706 iph->saddr,
707 skb->dev->ifindex)) != NULL) {
708 raw_err(raw_sk, skb, info);
709 raw_sk = sk_next(raw_sk);
710 iph = (struct iphdr *)skb->data;
711 }
712 }
713 read_unlock(&raw_v4_lock);
714
715 rcu_read_lock();
716 ipprot = rcu_dereference(inet_protos[hash]);
717 if (ipprot && ipprot->err_handler)
718 ipprot->err_handler(skb, info);
719 rcu_read_unlock();
720
721out:
722 return;
723out_err:
724 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
725 goto out;
726}
727
728
729/*
730 * Handle ICMP_REDIRECT.
731 */
732
733static void icmp_redirect(struct sk_buff *skb)
734{
735 struct iphdr *iph;
1da177e4
LT		 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;
1da177e4 747
88c7664f 748 switch (icmp_hdr(skb)->code & 7) {
1da177e4
LT		 749 case ICMP_REDIR_NET:
750 case ICMP_REDIR_NETTOS:
751 /*
752 * As per RFC recommendations now handle it as a host redirect.
753 */
754 case ICMP_REDIR_HOST:
755 case ICMP_REDIR_HOSTTOS:
eddc9ec5 756 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
88c7664f 757 icmp_hdr(skb)->un.gateway,
cef2685e 758 iph->saddr, skb->dev);
1da177e4 759 break;
e905a9ed 760 }
1da177e4
LT		 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
88c7664f 785 icmp_param.data.icmph = *icmp_hdr(skb);
1da177e4
LT		 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();
88c7664f 821 icmp_param.data.icmph = *icmp_hdr(skb);
1da177e4
LT		 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)) {
a144ea4b 900 __be32 _mask, *mp;
1da177e4
LT		 901
902 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
09a62660 903 BUG_ON(mp == NULL);
1da177e4
LT		 904 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
905 if (*mp == ifa->ifa_mask &&
906 inet_ifa_match(rt->rt_src, ifa))
907 break;
908 }
909 if (!ifa && net_ratelimit()) {
910 printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
911 "%s/%u.%u.%u.%u\n",
912 NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
913 }
914 }
915 rcu_read_unlock();
916 in_dev_put(in_dev);
917out:;
918}
919
920static void icmp_discard(struct sk_buff *skb)
921{
922}
923
924/*
925 * Deal with incoming ICMP packets.
926 */
927int icmp_rcv(struct sk_buff *skb)
928{
929 struct icmphdr *icmph;
930 struct rtable *rt = (struct rtable *)skb->dst;
931
932 ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
933
934 switch (skb->ip_summed) {
84fa7933 935 case CHECKSUM_COMPLETE:
d3bc23e7 936 if (!csum_fold(skb->csum))
1da177e4 937 break;
fb286bb2 938 /* fall through */
1da177e4 939 case CHECKSUM_NONE:
fb286bb2
HX		 940 skb->csum = 0;
941 if (__skb_checksum_complete(skb))
1da177e4 942 goto error;
1da177e4
LT		 943 }
944
945 if (!pskb_pull(skb, sizeof(struct icmphdr)))
946 goto error;
947
88c7664f 948 icmph = icmp_hdr(skb);
1da177e4 949
96793b48 950 ICMPMSGIN_INC_STATS_BH(icmph->type);
1da177e4
LT		 951 /*
952 * 18 is the highest 'known' ICMP type. Anything else is a mystery
953 *
954 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
955 * discarded.
956 */
957 if (icmph->type > NR_ICMP_TYPES)
958 goto error;
959
960
961 /*
962 * Parse the ICMP message
963 */
964
e905a9ed 965 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1da177e4
LT		 966 /*
967 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
968 * silently ignored (we let user decide with a sysctl).
969 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
970 * discarded if to broadcast/multicast.
971 */
4c866aa7
AK		 972 if ((icmph->type == ICMP_ECHO ||
973 icmph->type == ICMP_TIMESTAMP) &&
1da177e4
LT		 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;
e905a9ed 982 }
1da177e4
LT		 983 }
984
1da177e4
LT		 985 icmp_pointers[icmph->type].handler(skb);
986
987drop:
988 kfree_skb(skb);
989 return 0;
990error:
991 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
992 goto drop;
993}
994
995/*
996 * This table is the definition of how we handle ICMP.
997 */
9b5b5cff 998static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1da177e4 999 [ICMP_ECHOREPLY] = {
1da177e4
LT		 1000 .handler = icmp_discard,
1001 },
1002 [1] = {
1da177e4
LT		 1003 .handler = icmp_discard,
1004 .error = 1,
1005 },
1006 [2] = {
1da177e4
LT		 1007 .handler = icmp_discard,
1008 .error = 1,
1009 },
1010 [ICMP_DEST_UNREACH] = {
1da177e4
LT		 1011 .handler = icmp_unreach,
1012 .error = 1,
1013 },
1014 [ICMP_SOURCE_QUENCH] = {
1da177e4
LT		 1015 .handler = icmp_unreach,
1016 .error = 1,
1017 },
1018 [ICMP_REDIRECT] = {
1da177e4
LT		 1019 .handler = icmp_redirect,
1020 .error = 1,
1021 },
1022 [6] = {
1da177e4
LT		 1023 .handler = icmp_discard,
1024 .error = 1,
1025 },
1026 [7] = {
1da177e4
LT		 1027 .handler = icmp_discard,
1028 .error = 1,
1029 },
1030 [ICMP_ECHO] = {
1da177e4
LT		 1031 .handler = icmp_echo,
1032 },
1033 [9] = {
1da177e4
LT		 1034 .handler = icmp_discard,
1035 .error = 1,
1036 },
1037 [10] = {
1da177e4
LT		 1038 .handler = icmp_discard,
1039 .error = 1,
1040 },
1041 [ICMP_TIME_EXCEEDED] = {
1da177e4
LT		 1042 .handler = icmp_unreach,
1043 .error = 1,
1044 },
1045 [ICMP_PARAMETERPROB] = {
1da177e4
LT		 1046 .handler = icmp_unreach,
1047 .error = 1,
1048 },
1049 [ICMP_TIMESTAMP] = {
1da177e4
LT		 1050 .handler = icmp_timestamp,
1051 },
1052 [ICMP_TIMESTAMPREPLY] = {
1da177e4
LT		 1053 .handler = icmp_discard,
1054 },
1055 [ICMP_INFO_REQUEST] = {
1da177e4
LT		 1056 .handler = icmp_discard,
1057 },
e905a9ed 1058 [ICMP_INFO_REPLY] = {
1da177e4
LT		 1059 .handler = icmp_discard,
1060 },
1061 [ICMP_ADDRESS] = {
1da177e4
LT		 1062 .handler = icmp_address,
1063 },
1064 [ICMP_ADDRESSREPLY] = {
1da177e4
LT		 1065 .handler = icmp_address_reply,
1066 },
1067};
1068
1069void __init icmp_init(struct net_proto_family *ops)
1070{
1071 struct inet_sock *inet;
1072 int i;
1073
6f912042 1074 for_each_possible_cpu(i) {
1da177e4
LT		 1075 int err;
1076
1da177e4
LT		 1077 err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
1078 &per_cpu(__icmp_socket, i));
1079
1080 if (err < 0)
1081 panic("Failed to create the ICMP control socket.\n");
1082
1083 per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
1084
1085 /* Enough space for 2 64K ICMP packets, including
1086 * sk_buff struct overhead.
1087 */
1088 per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
1089 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1090
1091 inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
1092 inet->uc_ttl = -1;
1093 inet->pmtudisc = IP_PMTUDISC_DONT;
1094
1095 /* Unhash it so that IP input processing does not even
1096 * see it, we do not wish this socket to see incoming
1097 * packets.
1098 */
1099 per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
1100 }
1101}
1102
1103EXPORT_SYMBOL(icmp_err_convert);
1104EXPORT_SYMBOL(icmp_send);
1105EXPORT_SYMBOL(icmp_statistics);
1106EXPORT_SYMBOL(xrlim_allow);
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