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[thirdparty/linux.git] / net / ipv4 / icmp.c
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/module.h>
68 #include <linux/types.h>
69 #include <linux/jiffies.h>
70 #include <linux/kernel.h>
71 #include <linux/fcntl.h>
72 #include <linux/socket.h>
73 #include <linux/in.h>
74 #include <linux/inet.h>
75 #include <linux/inetdevice.h>
76 #include <linux/netdevice.h>
77 #include <linux/string.h>
78 #include <linux/netfilter_ipv4.h>
79 #include <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
100 struct icmp_bxm {
101 struct sk_buff *skb;
102 int offset;
103 int data_len;
104
105 struct {
106 struct icmphdr icmph;
107 __be32 times[3];
108 } data;
109 int head_len;
110 struct ip_options replyopts;
111 unsigned char optbuf[40];
112 };
113
114 /*
115 * Statistics
116 */
117 DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly;
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
122 struct 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. */
190 int sysctl_icmp_echo_ignore_all __read_mostly;
191 int sysctl_icmp_echo_ignore_broadcasts __read_mostly = 1;
192
193 /* Control parameter - ignore bogus broadcast responses? */
194 int sysctl_icmp_ignore_bogus_error_responses __read_mostly = 1;
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
208 int sysctl_icmp_ratelimit __read_mostly = 1 * HZ;
209 int sysctl_icmp_ratemask __read_mostly = 0x1818;
210 int sysctl_icmp_errors_use_inbound_ifaddr __read_mostly;
211
212 /*
213 * ICMP control array. This specifies what to do with each ICMP.
214 */
215
216 struct 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
223 static const 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 */
232 static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
233 #define icmp_socket __get_cpu_var(__icmp_socket)
234
235 static __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
249 static 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
276 int 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
293 static 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);
312 out:
313 return rc;
314 }
315
316 /*
317 * Maintain the counters used in the SNMP statistics for outgoing ICMP
318 */
319 static 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 */
331 static 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 __wsum 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
347 static 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 if (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) < 0)
356 ip_flush_pending_frames(icmp_socket->sk);
357 else if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
358 struct icmphdr *icmph = icmp_hdr(skb);
359 __wsum 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
378 static 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 __be32 daddr;
385
386 if (ip_options_echo(&icmp_param->replyopts, skb))
387 return;
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 = ip_hdr(skb)->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(ip_hdr(skb)->tos) } },
408 .proto = IPPROTO_ICMP };
409 security_skb_classify_flow(skb, &fl);
410 if (ip_route_output_key(&rt, &fl))
411 goto out_unlock;
412 }
413 if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
414 icmp_param->data.icmph.code))
415 icmp_push_reply(icmp_param, &ipc, rt);
416 ip_rt_put(rt);
417 out_unlock:
418 icmp_xmit_unlock();
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
433 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 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 __be32 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 = ip_hdr(skb_in);
452
453 if ((u8 *)iph < skb_in->head ||
454 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
455 goto out;
456
457 /*
458 * No replies to physical multicast/broadcast
459 */
460 if (skb_in->pkt_type != PACKET_HOST)
461 goto out;
462
463 /*
464 * Now check at the protocol level
465 */
466 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
467 goto out;
468
469 /*
470 * Only reply to fragment 0. We byte re-order the constant
471 * mask for efficiency.
472 */
473 if (iph->frag_off & htons(IP_OFFSET))
474 goto out;
475
476 /*
477 * If we send an ICMP error to an ICMP error a mess would result..
478 */
479 if (icmp_pointers[type].error) {
480 /*
481 * We are an error, check if we are replying to an
482 * ICMP error
483 */
484 if (iph->protocol == IPPROTO_ICMP) {
485 u8 _inner_type, *itp;
486
487 itp = skb_header_pointer(skb_in,
488 skb_network_header(skb_in) +
489 (iph->ihl << 2) +
490 offsetof(struct icmphdr,
491 type) -
492 skb_in->data,
493 sizeof(_inner_type),
494 &_inner_type);
495 if (itp == NULL)
496 goto out;
497
498 /*
499 * Assume any unknown ICMP type is an error. This
500 * isn't specified by the RFC, but think about it..
501 */
502 if (*itp > NR_ICMP_TYPES ||
503 icmp_pointers[*itp].error)
504 goto out;
505 }
506 }
507
508 if (icmp_xmit_lock())
509 return;
510
511 /*
512 * Construct source address and options.
513 */
514
515 saddr = iph->daddr;
516 if (!(rt->rt_flags & RTCF_LOCAL)) {
517 if (sysctl_icmp_errors_use_inbound_ifaddr)
518 saddr = inet_select_addr(skb_in->dev, 0, RT_SCOPE_LINK);
519 else
520 saddr = 0;
521 }
522
523 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
524 IPTOS_PREC_INTERNETCONTROL) :
525 iph->tos;
526
527 if (ip_options_echo(&icmp_param.replyopts, skb_in))
528 goto out_unlock;
529
530
531 /*
532 * Prepare data for ICMP header.
533 */
534
535 icmp_param.data.icmph.type = type;
536 icmp_param.data.icmph.code = code;
537 icmp_param.data.icmph.un.gateway = info;
538 icmp_param.data.icmph.checksum = 0;
539 icmp_param.skb = skb_in;
540 icmp_param.offset = skb_network_offset(skb_in);
541 icmp_out_count(icmp_param.data.icmph.type);
542 inet_sk(icmp_socket->sk)->tos = tos;
543 ipc.addr = iph->saddr;
544 ipc.opt = &icmp_param.replyopts;
545
546 {
547 struct flowi fl = {
548 .nl_u = {
549 .ip4_u = {
550 .daddr = icmp_param.replyopts.srr ?
551 icmp_param.replyopts.faddr :
552 iph->saddr,
553 .saddr = saddr,
554 .tos = RT_TOS(tos)
555 }
556 },
557 .proto = IPPROTO_ICMP,
558 .uli_u = {
559 .icmpt = {
560 .type = type,
561 .code = code
562 }
563 }
564 };
565 security_skb_classify_flow(skb_in, &fl);
566 if (ip_route_output_key(&rt, &fl))
567 goto out_unlock;
568 }
569
570 if (!icmpv4_xrlim_allow(rt, type, code))
571 goto ende;
572
573 /* RFC says return as much as we can without exceeding 576 bytes. */
574
575 room = dst_mtu(&rt->u.dst);
576 if (room > 576)
577 room = 576;
578 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
579 room -= sizeof(struct icmphdr);
580
581 icmp_param.data_len = skb_in->len - icmp_param.offset;
582 if (icmp_param.data_len > room)
583 icmp_param.data_len = room;
584 icmp_param.head_len = sizeof(struct icmphdr);
585
586 icmp_push_reply(&icmp_param, &ipc, rt);
587 ende:
588 ip_rt_put(rt);
589 out_unlock:
590 icmp_xmit_unlock();
591 out:;
592 }
593
594
595 /*
596 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
597 */
598
599 static void icmp_unreach(struct sk_buff *skb)
600 {
601 struct iphdr *iph;
602 struct icmphdr *icmph;
603 int hash, protocol;
604 struct net_protocol *ipprot;
605 struct sock *raw_sk;
606 u32 info = 0;
607
608 /*
609 * Incomplete header ?
610 * Only checks for the IP header, there should be an
611 * additional check for longer headers in upper levels.
612 */
613
614 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
615 goto out_err;
616
617 icmph = icmp_hdr(skb);
618 iph = (struct iphdr *)skb->data;
619
620 if (iph->ihl < 5) /* Mangled header, drop. */
621 goto out_err;
622
623 if (icmph->type == ICMP_DEST_UNREACH) {
624 switch (icmph->code & 15) {
625 case ICMP_NET_UNREACH:
626 case ICMP_HOST_UNREACH:
627 case ICMP_PROT_UNREACH:
628 case ICMP_PORT_UNREACH:
629 break;
630 case ICMP_FRAG_NEEDED:
631 if (ipv4_config.no_pmtu_disc) {
632 LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: "
633 "fragmentation needed "
634 "and DF set.\n",
635 NIPQUAD(iph->daddr));
636 } else {
637 info = ip_rt_frag_needed(iph,
638 ntohs(icmph->un.frag.mtu));
639 if (!info)
640 goto out;
641 }
642 break;
643 case ICMP_SR_FAILED:
644 LIMIT_NETDEBUG(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(ip_hdr(skb)->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
720 out:
721 return;
722 out_err:
723 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
724 goto out;
725 }
726
727
728 /*
729 * Handle ICMP_REDIRECT.
730 */
731
732 static void icmp_redirect(struct sk_buff *skb)
733 {
734 struct iphdr *iph;
735
736 if (skb->len < sizeof(struct iphdr))
737 goto out_err;
738
739 /*
740 * Get the copied header of the packet that caused the redirect
741 */
742 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
743 goto out;
744
745 iph = (struct iphdr *)skb->data;
746
747 switch (icmp_hdr(skb)->code & 7) {
748 case ICMP_REDIR_NET:
749 case ICMP_REDIR_NETTOS:
750 /*
751 * As per RFC recommendations now handle it as a host redirect.
752 */
753 case ICMP_REDIR_HOST:
754 case ICMP_REDIR_HOSTTOS:
755 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
756 icmp_hdr(skb)->un.gateway,
757 iph->saddr, skb->dev);
758 break;
759 }
760 out:
761 return;
762 out_err:
763 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
764 goto out;
765 }
766
767 /*
768 * Handle ICMP_ECHO ("ping") requests.
769 *
770 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
771 * requests.
772 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
773 * included in the reply.
774 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
775 * echo requests, MUST have default=NOT.
776 * See also WRT handling of options once they are done and working.
777 */
778
779 static void icmp_echo(struct sk_buff *skb)
780 {
781 if (!sysctl_icmp_echo_ignore_all) {
782 struct icmp_bxm icmp_param;
783
784 icmp_param.data.icmph = *icmp_hdr(skb);
785 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
786 icmp_param.skb = skb;
787 icmp_param.offset = 0;
788 icmp_param.data_len = skb->len;
789 icmp_param.head_len = sizeof(struct icmphdr);
790 icmp_reply(&icmp_param, skb);
791 }
792 }
793
794 /*
795 * Handle ICMP Timestamp requests.
796 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
797 * SHOULD be in the kernel for minimum random latency.
798 * MUST be accurate to a few minutes.
799 * MUST be updated at least at 15Hz.
800 */
801 static void icmp_timestamp(struct sk_buff *skb)
802 {
803 struct timeval tv;
804 struct icmp_bxm icmp_param;
805 /*
806 * Too short.
807 */
808 if (skb->len < 4)
809 goto out_err;
810
811 /*
812 * Fill in the current time as ms since midnight UT:
813 */
814 do_gettimeofday(&tv);
815 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 +
816 tv.tv_usec / 1000);
817 icmp_param.data.times[2] = icmp_param.data.times[1];
818 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
819 BUG();
820 icmp_param.data.icmph = *icmp_hdr(skb);
821 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
822 icmp_param.data.icmph.code = 0;
823 icmp_param.skb = skb;
824 icmp_param.offset = 0;
825 icmp_param.data_len = 0;
826 icmp_param.head_len = sizeof(struct icmphdr) + 12;
827 icmp_reply(&icmp_param, skb);
828 out:
829 return;
830 out_err:
831 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
832 goto out;
833 }
834
835
836 /*
837 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
838 *
839 * RFC1122 (3.2.2.9). A host MUST only send replies to
840 * ADDRESS_MASK requests if it's been configured as an address mask
841 * agent. Receiving a request doesn't constitute implicit permission to
842 * act as one. Of course, implementing this correctly requires (SHOULD)
843 * a way to turn the functionality on and off. Another one for sysctl(),
844 * I guess. -- MS
845 *
846 * RFC1812 (4.3.3.9). A router MUST implement it.
847 * A router SHOULD have switch turning it on/off.
848 * This switch MUST be ON by default.
849 *
850 * Gratuitous replies, zero-source replies are not implemented,
851 * that complies with RFC. DO NOT implement them!!! All the idea
852 * of broadcast addrmask replies as specified in RFC950 is broken.
853 * The problem is that it is not uncommon to have several prefixes
854 * on one physical interface. Moreover, addrmask agent can even be
855 * not aware of existing another prefixes.
856 * If source is zero, addrmask agent cannot choose correct prefix.
857 * Gratuitous mask announcements suffer from the same problem.
858 * RFC1812 explains it, but still allows to use ADDRMASK,
859 * that is pretty silly. --ANK
860 *
861 * All these rules are so bizarre, that I removed kernel addrmask
862 * support at all. It is wrong, it is obsolete, nobody uses it in
863 * any case. --ANK
864 *
865 * Furthermore you can do it with a usermode address agent program
866 * anyway...
867 */
868
869 static void icmp_address(struct sk_buff *skb)
870 {
871 #if 0
872 if (net_ratelimit())
873 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
874 #endif
875 }
876
877 /*
878 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
879 * loudly if an inconsistency is found.
880 */
881
882 static void icmp_address_reply(struct sk_buff *skb)
883 {
884 struct rtable *rt = (struct rtable *)skb->dst;
885 struct net_device *dev = skb->dev;
886 struct in_device *in_dev;
887 struct in_ifaddr *ifa;
888
889 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
890 goto out;
891
892 in_dev = in_dev_get(dev);
893 if (!in_dev)
894 goto out;
895 rcu_read_lock();
896 if (in_dev->ifa_list &&
897 IN_DEV_LOG_MARTIANS(in_dev) &&
898 IN_DEV_FORWARD(in_dev)) {
899 __be32 _mask, *mp;
900
901 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
902 BUG_ON(mp == NULL);
903 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
904 if (*mp == ifa->ifa_mask &&
905 inet_ifa_match(rt->rt_src, ifa))
906 break;
907 }
908 if (!ifa && net_ratelimit()) {
909 printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
910 "%s/%u.%u.%u.%u\n",
911 NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
912 }
913 }
914 rcu_read_unlock();
915 in_dev_put(in_dev);
916 out:;
917 }
918
919 static void icmp_discard(struct sk_buff *skb)
920 {
921 }
922
923 /*
924 * Deal with incoming ICMP packets.
925 */
926 int icmp_rcv(struct sk_buff *skb)
927 {
928 struct icmphdr *icmph;
929 struct rtable *rt = (struct rtable *)skb->dst;
930
931 ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
932
933 switch (skb->ip_summed) {
934 case CHECKSUM_COMPLETE:
935 if (!csum_fold(skb->csum))
936 break;
937 /* fall through */
938 case CHECKSUM_NONE:
939 skb->csum = 0;
940 if (__skb_checksum_complete(skb))
941 goto error;
942 }
943
944 if (!pskb_pull(skb, sizeof(struct icmphdr)))
945 goto error;
946
947 icmph = icmp_hdr(skb);
948
949 /*
950 * 18 is the highest 'known' ICMP type. Anything else is a mystery
951 *
952 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
953 * discarded.
954 */
955 if (icmph->type > NR_ICMP_TYPES)
956 goto error;
957
958
959 /*
960 * Parse the ICMP message
961 */
962
963 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
964 /*
965 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
966 * silently ignored (we let user decide with a sysctl).
967 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
968 * discarded if to broadcast/multicast.
969 */
970 if ((icmph->type == ICMP_ECHO ||
971 icmph->type == ICMP_TIMESTAMP) &&
972 sysctl_icmp_echo_ignore_broadcasts) {
973 goto error;
974 }
975 if (icmph->type != ICMP_ECHO &&
976 icmph->type != ICMP_TIMESTAMP &&
977 icmph->type != ICMP_ADDRESS &&
978 icmph->type != ICMP_ADDRESSREPLY) {
979 goto error;
980 }
981 }
982
983 ICMP_INC_STATS_BH(icmp_pointers[icmph->type].input_entry);
984 icmp_pointers[icmph->type].handler(skb);
985
986 drop:
987 kfree_skb(skb);
988 return 0;
989 error:
990 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
991 goto drop;
992 }
993
994 /*
995 * This table is the definition of how we handle ICMP.
996 */
997 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
998 [ICMP_ECHOREPLY] = {
999 .output_entry = ICMP_MIB_OUTECHOREPS,
1000 .input_entry = ICMP_MIB_INECHOREPS,
1001 .handler = icmp_discard,
1002 },
1003 [1] = {
1004 .output_entry = ICMP_MIB_DUMMY,
1005 .input_entry = ICMP_MIB_INERRORS,
1006 .handler = icmp_discard,
1007 .error = 1,
1008 },
1009 [2] = {
1010 .output_entry = ICMP_MIB_DUMMY,
1011 .input_entry = ICMP_MIB_INERRORS,
1012 .handler = icmp_discard,
1013 .error = 1,
1014 },
1015 [ICMP_DEST_UNREACH] = {
1016 .output_entry = ICMP_MIB_OUTDESTUNREACHS,
1017 .input_entry = ICMP_MIB_INDESTUNREACHS,
1018 .handler = icmp_unreach,
1019 .error = 1,
1020 },
1021 [ICMP_SOURCE_QUENCH] = {
1022 .output_entry = ICMP_MIB_OUTSRCQUENCHS,
1023 .input_entry = ICMP_MIB_INSRCQUENCHS,
1024 .handler = icmp_unreach,
1025 .error = 1,
1026 },
1027 [ICMP_REDIRECT] = {
1028 .output_entry = ICMP_MIB_OUTREDIRECTS,
1029 .input_entry = ICMP_MIB_INREDIRECTS,
1030 .handler = icmp_redirect,
1031 .error = 1,
1032 },
1033 [6] = {
1034 .output_entry = ICMP_MIB_DUMMY,
1035 .input_entry = ICMP_MIB_INERRORS,
1036 .handler = icmp_discard,
1037 .error = 1,
1038 },
1039 [7] = {
1040 .output_entry = ICMP_MIB_DUMMY,
1041 .input_entry = ICMP_MIB_INERRORS,
1042 .handler = icmp_discard,
1043 .error = 1,
1044 },
1045 [ICMP_ECHO] = {
1046 .output_entry = ICMP_MIB_OUTECHOS,
1047 .input_entry = ICMP_MIB_INECHOS,
1048 .handler = icmp_echo,
1049 },
1050 [9] = {
1051 .output_entry = ICMP_MIB_DUMMY,
1052 .input_entry = ICMP_MIB_INERRORS,
1053 .handler = icmp_discard,
1054 .error = 1,
1055 },
1056 [10] = {
1057 .output_entry = ICMP_MIB_DUMMY,
1058 .input_entry = ICMP_MIB_INERRORS,
1059 .handler = icmp_discard,
1060 .error = 1,
1061 },
1062 [ICMP_TIME_EXCEEDED] = {
1063 .output_entry = ICMP_MIB_OUTTIMEEXCDS,
1064 .input_entry = ICMP_MIB_INTIMEEXCDS,
1065 .handler = icmp_unreach,
1066 .error = 1,
1067 },
1068 [ICMP_PARAMETERPROB] = {
1069 .output_entry = ICMP_MIB_OUTPARMPROBS,
1070 .input_entry = ICMP_MIB_INPARMPROBS,
1071 .handler = icmp_unreach,
1072 .error = 1,
1073 },
1074 [ICMP_TIMESTAMP] = {
1075 .output_entry = ICMP_MIB_OUTTIMESTAMPS,
1076 .input_entry = ICMP_MIB_INTIMESTAMPS,
1077 .handler = icmp_timestamp,
1078 },
1079 [ICMP_TIMESTAMPREPLY] = {
1080 .output_entry = ICMP_MIB_OUTTIMESTAMPREPS,
1081 .input_entry = ICMP_MIB_INTIMESTAMPREPS,
1082 .handler = icmp_discard,
1083 },
1084 [ICMP_INFO_REQUEST] = {
1085 .output_entry = ICMP_MIB_DUMMY,
1086 .input_entry = ICMP_MIB_DUMMY,
1087 .handler = icmp_discard,
1088 },
1089 [ICMP_INFO_REPLY] = {
1090 .output_entry = ICMP_MIB_DUMMY,
1091 .input_entry = ICMP_MIB_DUMMY,
1092 .handler = icmp_discard,
1093 },
1094 [ICMP_ADDRESS] = {
1095 .output_entry = ICMP_MIB_OUTADDRMASKS,
1096 .input_entry = ICMP_MIB_INADDRMASKS,
1097 .handler = icmp_address,
1098 },
1099 [ICMP_ADDRESSREPLY] = {
1100 .output_entry = ICMP_MIB_OUTADDRMASKREPS,
1101 .input_entry = ICMP_MIB_INADDRMASKREPS,
1102 .handler = icmp_address_reply,
1103 },
1104 };
1105
1106 void __init icmp_init(struct net_proto_family *ops)
1107 {
1108 struct inet_sock *inet;
1109 int i;
1110
1111 for_each_possible_cpu(i) {
1112 int err;
1113
1114 err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
1115 &per_cpu(__icmp_socket, i));
1116
1117 if (err < 0)
1118 panic("Failed to create the ICMP control socket.\n");
1119
1120 per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
1121
1122 /* Enough space for 2 64K ICMP packets, including
1123 * sk_buff struct overhead.
1124 */
1125 per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
1126 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1127
1128 inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
1129 inet->uc_ttl = -1;
1130 inet->pmtudisc = IP_PMTUDISC_DONT;
1131
1132 /* Unhash it so that IP input processing does not even
1133 * see it, we do not wish this socket to see incoming
1134 * packets.
1135 */
1136 per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
1137 }
1138 }
1139
1140 EXPORT_SYMBOL(icmp_err_convert);
1141 EXPORT_SYMBOL(icmp_send);
1142 EXPORT_SYMBOL(icmp_statistics);
1143 EXPORT_SYMBOL(xrlim_allow);
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