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Linux 2.6.33-rc6
[cris-mirror.git] / net / ipv4 / icmp.c
blobfe11f60ce41ba645d7f9535e13524419f16dff90
1 /*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * Some of the function names and the icmp unreach table for this
12 * module were derived from [icmp.c 1.0.11 06/02/93] by
13 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
14 * Other than that this module is a complete rewrite.
15 *
16 * Fixes:
17 * Clemens Fruhwirth : introduce global icmp rate limiting
18 * with icmp type masking ability instead
19 * of broken per type icmp timeouts.
20 * Mike Shaver : RFC1122 checks.
21 * Alan Cox : Multicast ping reply as self.
22 * Alan Cox : Fix atomicity lockup in ip_build_xmit
23 * call.
24 * Alan Cox : Added 216,128 byte paths to the MTU
25 * code.
26 * Martin Mares : RFC1812 checks.
27 * Martin Mares : Can be configured to follow redirects
28 * if acting as a router _without_ a
29 * routing protocol (RFC 1812).
30 * Martin Mares : Echo requests may be configured to
31 * be ignored (RFC 1812).
32 * Martin Mares : Limitation of ICMP error message
33 * transmit rate (RFC 1812).
34 * Martin Mares : TOS and Precedence set correctly
35 * (RFC 1812).
36 * Martin Mares : Now copying as much data from the
37 * original packet as we can without
38 * exceeding 576 bytes (RFC 1812).
39 * Willy Konynenberg : Transparent proxying support.
40 * Keith Owens : RFC1191 correction for 4.2BSD based
41 * path MTU bug.
42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
43 * valid (RFC 1812).
44 * Andi Kleen : Check all packet lengths properly
45 * and moved all kfree_skb() up to
46 * icmp_rcv.
47 * Andi Kleen : Move the rate limit bookkeeping
48 * into the dest entry and use a token
49 * bucket filter (thanks to ANK). Make
50 * the rates sysctl configurable.
51 * Yu Tianli : Fixed two ugly bugs in icmp_send
52 * - IP option length was accounted wrongly
53 * - ICMP header length was not accounted
54 * at all.
55 * Tristan Greaves : Added sysctl option to ignore bogus
56 * broadcast responses from broken routers.
57 *
58 * To Fix:
59 *
60 * - Should use skb_pull() instead of all the manual checking.
61 * This would also greatly simply some upper layer error handlers. --AK
62 *
63 */
64
65 #include <linux/module.h>
66 #include <linux/types.h>
67 #include <linux/jiffies.h>
68 #include <linux/kernel.h>
69 #include <linux/fcntl.h>
70 #include <linux/socket.h>
71 #include <linux/in.h>
72 #include <linux/inet.h>
73 #include <linux/inetdevice.h>
74 #include <linux/netdevice.h>
75 #include <linux/string.h>
76 #include <linux/netfilter_ipv4.h>
77 #include <net/snmp.h>
78 #include <net/ip.h>
79 #include <net/route.h>
80 #include <net/protocol.h>
81 #include <net/icmp.h>
82 #include <net/tcp.h>
83 #include <net/udp.h>
84 #include <net/raw.h>
85 #include <linux/skbuff.h>
86 #include <net/sock.h>
87 #include <linux/errno.h>
88 #include <linux/timer.h>
89 #include <linux/init.h>
90 #include <asm/system.h>
91 #include <asm/uaccess.h>
92 #include <net/checksum.h>
93 #include <net/xfrm.h>
94 #include <net/inet_common.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 /* An array of errno for error messages from dest unreach. */
115 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
116
117 struct icmp_err icmp_err_convert[] = {
118 {
119 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
120 .fatal = 0,
121 },
122 {
123 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
124 .fatal = 0,
125 },
126 {
127 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
128 .fatal = 1,
129 },
130 {
131 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
132 .fatal = 1,
133 },
134 {
135 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
136 .fatal = 0,
137 },
138 {
139 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
140 .fatal = 0,
141 },
142 {
143 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
144 .fatal = 1,
145 },
146 {
147 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
148 .fatal = 1,
149 },
150 {
151 .errno = ENONET, /* ICMP_HOST_ISOLATED */
152 .fatal = 1,
153 },
154 {
155 .errno = ENETUNREACH, /* ICMP_NET_ANO */
156 .fatal = 1,
157 },
158 {
159 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
160 .fatal = 1,
161 },
162 {
163 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
164 .fatal = 0,
165 },
166 {
167 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
168 .fatal = 0,
169 },
170 {
171 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
172 .fatal = 1,
173 },
174 {
175 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
176 .fatal = 1,
177 },
178 {
179 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
180 .fatal = 1,
181 },
182 };
183
184 /*
185 * ICMP control array. This specifies what to do with each ICMP.
186 */
187
188 struct icmp_control {
189 void (*handler)(struct sk_buff *skb);
190 short error; /* This ICMP is classed as an error message */
191 };
192
193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
194
195 /*
196 * The ICMP socket(s). This is the most convenient way to flow control
197 * our ICMP output as well as maintain a clean interface throughout
198 * all layers. All Socketless IP sends will soon be gone.
199 *
200 * On SMP we have one ICMP socket per-cpu.
201 */
202 static struct sock *icmp_sk(struct net *net)
203 {
204 return net->ipv4.icmp_sk[smp_processor_id()];
205 }
206
207 static inline struct sock *icmp_xmit_lock(struct net *net)
208 {
209 struct sock *sk;
210
211 local_bh_disable();
212
213 sk = icmp_sk(net);
214
215 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
216 /* This can happen if the output path signals a
217 * dst_link_failure() for an outgoing ICMP packet.
218 */
219 local_bh_enable();
220 return NULL;
221 }
222 return sk;
223 }
224
225 static inline void icmp_xmit_unlock(struct sock *sk)
226 {
227 spin_unlock_bh(&sk->sk_lock.slock);
228 }
229
230 /*
231 * Send an ICMP frame.
232 */
233
234 /*
235 * Check transmit rate limitation for given message.
236 * The rate information is held in the destination cache now.
237 * This function is generic and could be used for other purposes
238 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
239 *
240 * Note that the same dst_entry fields are modified by functions in
241 * route.c too, but these work for packet destinations while xrlim_allow
242 * works for icmp destinations. This means the rate limiting information
243 * for one "ip object" is shared - and these ICMPs are twice limited:
244 * by source and by destination.
245 *
246 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
247 * SHOULD allow setting of rate limits
248 *
249 * Shared between ICMPv4 and ICMPv6.
250 */
251 #define XRLIM_BURST_FACTOR 6
252 int xrlim_allow(struct dst_entry *dst, int timeout)
253 {
254 unsigned long now, token = dst->rate_tokens;
255 int rc = 0;
256
257 now = jiffies;
258 token += now - dst->rate_last;
259 dst->rate_last = now;
260 if (token > XRLIM_BURST_FACTOR * timeout)
261 token = XRLIM_BURST_FACTOR * timeout;
262 if (token >= timeout) {
263 token -= timeout;
264 rc = 1;
265 }
266 dst->rate_tokens = token;
267 return rc;
268 }
269
270 static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
271 int type, int code)
272 {
273 struct dst_entry *dst = &rt->u.dst;
274 int rc = 1;
275
276 if (type > NR_ICMP_TYPES)
277 goto out;
278
279 /* Don't limit PMTU discovery. */
280 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
281 goto out;
282
283 /* No rate limit on loopback */
284 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
285 goto out;
286
287 /* Limit if icmp type is enabled in ratemask. */
288 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
289 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
290 out:
291 return rc;
292 }
293
294 /*
295 * Maintain the counters used in the SNMP statistics for outgoing ICMP
296 */
297 void icmp_out_count(struct net *net, unsigned char type)
298 {
299 ICMPMSGOUT_INC_STATS(net, type);
300 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
301 }
302
303 /*
304 * Checksum each fragment, and on the first include the headers and final
305 * checksum.
306 */
307 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
308 struct sk_buff *skb)
309 {
310 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
311 __wsum csum;
312
313 csum = skb_copy_and_csum_bits(icmp_param->skb,
314 icmp_param->offset + offset,
315 to, len, 0);
316
317 skb->csum = csum_block_add(skb->csum, csum, odd);
318 if (icmp_pointers[icmp_param->data.icmph.type].error)
319 nf_ct_attach(skb, icmp_param->skb);
320 return 0;
321 }
322
323 static void icmp_push_reply(struct icmp_bxm *icmp_param,
324 struct ipcm_cookie *ipc, struct rtable **rt)
325 {
326 struct sock *sk;
327 struct sk_buff *skb;
328
329 sk = icmp_sk(dev_net((*rt)->u.dst.dev));
330 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
331 icmp_param->data_len+icmp_param->head_len,
332 icmp_param->head_len,
333 ipc, rt, MSG_DONTWAIT) < 0)
334 ip_flush_pending_frames(sk);
335 else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
336 struct icmphdr *icmph = icmp_hdr(skb);
337 __wsum csum = 0;
338 struct sk_buff *skb1;
339
340 skb_queue_walk(&sk->sk_write_queue, skb1) {
341 csum = csum_add(csum, skb1->csum);
342 }
343 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
344 (char *)icmph,
345 icmp_param->head_len, csum);
346 icmph->checksum = csum_fold(csum);
347 skb->ip_summed = CHECKSUM_NONE;
348 ip_push_pending_frames(sk);
349 }
350 }
351
352 /*
353 * Driving logic for building and sending ICMP messages.
354 */
355
356 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
357 {
358 struct ipcm_cookie ipc;
359 struct rtable *rt = skb_rtable(skb);
360 struct net *net = dev_net(rt->u.dst.dev);
361 struct sock *sk;
362 struct inet_sock *inet;
363 __be32 daddr;
364
365 if (ip_options_echo(&icmp_param->replyopts, skb))
366 return;
367
368 sk = icmp_xmit_lock(net);
369 if (sk == NULL)
370 return;
371 inet = inet_sk(sk);
372
373 icmp_param->data.icmph.checksum = 0;
374
375 inet->tos = ip_hdr(skb)->tos;
376 daddr = ipc.addr = rt->rt_src;
377 ipc.opt = NULL;
378 ipc.shtx.flags = 0;
379 if (icmp_param->replyopts.optlen) {
380 ipc.opt = &icmp_param->replyopts;
381 if (ipc.opt->srr)
382 daddr = icmp_param->replyopts.faddr;
383 }
384 {
385 struct flowi fl = { .nl_u = { .ip4_u =
386 { .daddr = daddr,
387 .saddr = rt->rt_spec_dst,
388 .tos = RT_TOS(ip_hdr(skb)->tos) } },
389 .proto = IPPROTO_ICMP };
390 security_skb_classify_flow(skb, &fl);
391 if (ip_route_output_key(net, &rt, &fl))
392 goto out_unlock;
393 }
394 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
395 icmp_param->data.icmph.code))
396 icmp_push_reply(icmp_param, &ipc, &rt);
397 ip_rt_put(rt);
398 out_unlock:
399 icmp_xmit_unlock(sk);
400 }
401
402
403 /*
404 * Send an ICMP message in response to a situation
405 *
406 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
407 * MAY send more (we do).
408 * MUST NOT change this header information.
409 * MUST NOT reply to a multicast/broadcast IP address.
410 * MUST NOT reply to a multicast/broadcast MAC address.
411 * MUST reply to only the first fragment.
412 */
413
414 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
415 {
416 struct iphdr *iph;
417 int room;
418 struct icmp_bxm icmp_param;
419 struct rtable *rt = skb_rtable(skb_in);
420 struct ipcm_cookie ipc;
421 __be32 saddr;
422 u8 tos;
423 struct net *net;
424 struct sock *sk;
425
426 if (!rt)
427 goto out;
428 net = dev_net(rt->u.dst.dev);
429
430 /*
431 * Find the original header. It is expected to be valid, of course.
432 * Check this, icmp_send is called from the most obscure devices
433 * sometimes.
434 */
435 iph = ip_hdr(skb_in);
436
437 if ((u8 *)iph < skb_in->head ||
438 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
439 goto out;
440
441 /*
442 * No replies to physical multicast/broadcast
443 */
444 if (skb_in->pkt_type != PACKET_HOST)
445 goto out;
446
447 /*
448 * Now check at the protocol level
449 */
450 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
451 goto out;
452
453 /*
454 * Only reply to fragment 0. We byte re-order the constant
455 * mask for efficiency.
456 */
457 if (iph->frag_off & htons(IP_OFFSET))
458 goto out;
459
460 /*
461 * If we send an ICMP error to an ICMP error a mess would result..
462 */
463 if (icmp_pointers[type].error) {
464 /*
465 * We are an error, check if we are replying to an
466 * ICMP error
467 */
468 if (iph->protocol == IPPROTO_ICMP) {
469 u8 _inner_type, *itp;
470
471 itp = skb_header_pointer(skb_in,
472 skb_network_header(skb_in) +
473 (iph->ihl << 2) +
474 offsetof(struct icmphdr,
475 type) -
476 skb_in->data,
477 sizeof(_inner_type),
478 &_inner_type);
479 if (itp == NULL)
480 goto out;
481
482 /*
483 * Assume any unknown ICMP type is an error. This
484 * isn't specified by the RFC, but think about it..
485 */
486 if (*itp > NR_ICMP_TYPES ||
487 icmp_pointers[*itp].error)
488 goto out;
489 }
490 }
491
492 sk = icmp_xmit_lock(net);
493 if (sk == NULL)
494 return;
495
496 /*
497 * Construct source address and options.
498 */
499
500 saddr = iph->daddr;
501 if (!(rt->rt_flags & RTCF_LOCAL)) {
502 struct net_device *dev = NULL;
503
504 rcu_read_lock();
505 if (rt->fl.iif &&
506 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
507 dev = dev_get_by_index_rcu(net, rt->fl.iif);
508
509 if (dev)
510 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
511 else
512 saddr = 0;
513 rcu_read_unlock();
514 }
515
516 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
517 IPTOS_PREC_INTERNETCONTROL) :
518 iph->tos;
519
520 if (ip_options_echo(&icmp_param.replyopts, skb_in))
521 goto out_unlock;
522
523
524 /*
525 * Prepare data for ICMP header.
526 */
527
528 icmp_param.data.icmph.type = type;
529 icmp_param.data.icmph.code = code;
530 icmp_param.data.icmph.un.gateway = info;
531 icmp_param.data.icmph.checksum = 0;
532 icmp_param.skb = skb_in;
533 icmp_param.offset = skb_network_offset(skb_in);
534 inet_sk(sk)->tos = tos;
535 ipc.addr = iph->saddr;
536 ipc.opt = &icmp_param.replyopts;
537 ipc.shtx.flags = 0;
538
539 {
540 struct flowi fl = {
541 .nl_u = {
542 .ip4_u = {
543 .daddr = icmp_param.replyopts.srr ?
544 icmp_param.replyopts.faddr :
545 iph->saddr,
546 .saddr = saddr,
547 .tos = RT_TOS(tos)
548 }
549 },
550 .proto = IPPROTO_ICMP,
551 .uli_u = {
552 .icmpt = {
553 .type = type,
554 .code = code
555 }
556 }
557 };
558 int err;
559 struct rtable *rt2;
560
561 security_skb_classify_flow(skb_in, &fl);
562 if (__ip_route_output_key(net, &rt, &fl))
563 goto out_unlock;
564
565 /* No need to clone since we're just using its address. */
566 rt2 = rt;
567
568 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
569 switch (err) {
570 case 0:
571 if (rt != rt2)
572 goto route_done;
573 break;
574 case -EPERM:
575 rt = NULL;
576 break;
577 default:
578 goto out_unlock;
579 }
580
581 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
582 goto relookup_failed;
583
584 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
585 err = __ip_route_output_key(net, &rt2, &fl);
586 else {
587 struct flowi fl2 = {};
588 struct dst_entry *odst;
589
590 fl2.fl4_dst = fl.fl4_src;
591 if (ip_route_output_key(net, &rt2, &fl2))
592 goto relookup_failed;
593
594 /* Ugh! */
595 odst = skb_dst(skb_in);
596 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
597 RT_TOS(tos), rt2->u.dst.dev);
598
599 dst_release(&rt2->u.dst);
600 rt2 = skb_rtable(skb_in);
601 skb_dst_set(skb_in, odst);
602 }
603
604 if (err)
605 goto relookup_failed;
606
607 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
608 XFRM_LOOKUP_ICMP);
609 switch (err) {
610 case 0:
611 dst_release(&rt->u.dst);
612 rt = rt2;
613 break;
614 case -EPERM:
615 goto ende;
616 default:
617 relookup_failed:
618 if (!rt)
619 goto out_unlock;
620 break;
621 }
622 }
623
624 route_done:
625 if (!icmpv4_xrlim_allow(net, rt, type, code))
626 goto ende;
627
628 /* RFC says return as much as we can without exceeding 576 bytes. */
629
630 room = dst_mtu(&rt->u.dst);
631 if (room > 576)
632 room = 576;
633 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
634 room -= sizeof(struct icmphdr);
635
636 icmp_param.data_len = skb_in->len - icmp_param.offset;
637 if (icmp_param.data_len > room)
638 icmp_param.data_len = room;
639 icmp_param.head_len = sizeof(struct icmphdr);
640
641 icmp_push_reply(&icmp_param, &ipc, &rt);
642 ende:
643 ip_rt_put(rt);
644 out_unlock:
645 icmp_xmit_unlock(sk);
646 out:;
647 }
648
649
650 /*
651 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
652 */
653
654 static void icmp_unreach(struct sk_buff *skb)
655 {
656 struct iphdr *iph;
657 struct icmphdr *icmph;
658 int hash, protocol;
659 const struct net_protocol *ipprot;
660 u32 info = 0;
661 struct net *net;
662
663 net = dev_net(skb_dst(skb)->dev);
664
665 /*
666 * Incomplete header ?
667 * Only checks for the IP header, there should be an
668 * additional check for longer headers in upper levels.
669 */
670
671 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
672 goto out_err;
673
674 icmph = icmp_hdr(skb);
675 iph = (struct iphdr *)skb->data;
676
677 if (iph->ihl < 5) /* Mangled header, drop. */
678 goto out_err;
679
680 if (icmph->type == ICMP_DEST_UNREACH) {
681 switch (icmph->code & 15) {
682 case ICMP_NET_UNREACH:
683 case ICMP_HOST_UNREACH:
684 case ICMP_PROT_UNREACH:
685 case ICMP_PORT_UNREACH:
686 break;
687 case ICMP_FRAG_NEEDED:
688 if (ipv4_config.no_pmtu_disc) {
689 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
690 &iph->daddr);
691 } else {
692 info = ip_rt_frag_needed(net, iph,
693 ntohs(icmph->un.frag.mtu),
694 skb->dev);
695 if (!info)
696 goto out;
697 }
698 break;
699 case ICMP_SR_FAILED:
700 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
701 &iph->daddr);
702 break;
703 default:
704 break;
705 }
706 if (icmph->code > NR_ICMP_UNREACH)
707 goto out;
708 } else if (icmph->type == ICMP_PARAMETERPROB)
709 info = ntohl(icmph->un.gateway) >> 24;
710
711 /*
712 * Throw it at our lower layers
713 *
714 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
715 * header.
716 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
717 * transport layer.
718 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
719 * transport layer.
720 */
721
722 /*
723 * Check the other end isnt violating RFC 1122. Some routers send
724 * bogus responses to broadcast frames. If you see this message
725 * first check your netmask matches at both ends, if it does then
726 * get the other vendor to fix their kit.
727 */
728
729 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
730 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
731 if (net_ratelimit())
732 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
733 "type %u, code %u "
734 "error to a broadcast: %pI4 on %s\n",
735 &ip_hdr(skb)->saddr,
736 icmph->type, icmph->code,
737 &iph->daddr,
738 skb->dev->name);
739 goto out;
740 }
741
742 /* Checkin full IP header plus 8 bytes of protocol to
743 * avoid additional coding at protocol handlers.
744 */
745 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
746 goto out;
747
748 iph = (struct iphdr *)skb->data;
749 protocol = iph->protocol;
750
751 /*
752 * Deliver ICMP message to raw sockets. Pretty useless feature?
753 */
754 raw_icmp_error(skb, protocol, info);
755
756 hash = protocol & (MAX_INET_PROTOS - 1);
757 rcu_read_lock();
758 ipprot = rcu_dereference(inet_protos[hash]);
759 if (ipprot && ipprot->err_handler)
760 ipprot->err_handler(skb, info);
761 rcu_read_unlock();
762
763 out:
764 return;
765 out_err:
766 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
767 goto out;
768 }
769
770
771 /*
772 * Handle ICMP_REDIRECT.
773 */
774
775 static void icmp_redirect(struct sk_buff *skb)
776 {
777 struct iphdr *iph;
778
779 if (skb->len < sizeof(struct iphdr))
780 goto out_err;
781
782 /*
783 * Get the copied header of the packet that caused the redirect
784 */
785 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
786 goto out;
787
788 iph = (struct iphdr *)skb->data;
789
790 switch (icmp_hdr(skb)->code & 7) {
791 case ICMP_REDIR_NET:
792 case ICMP_REDIR_NETTOS:
793 /*
794 * As per RFC recommendations now handle it as a host redirect.
795 */
796 case ICMP_REDIR_HOST:
797 case ICMP_REDIR_HOSTTOS:
798 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
799 icmp_hdr(skb)->un.gateway,
800 iph->saddr, skb->dev);
801 break;
802 }
803 out:
804 return;
805 out_err:
806 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
807 goto out;
808 }
809
810 /*
811 * Handle ICMP_ECHO ("ping") requests.
812 *
813 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
814 * requests.
815 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
816 * included in the reply.
817 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
818 * echo requests, MUST have default=NOT.
819 * See also WRT handling of options once they are done and working.
820 */
821
822 static void icmp_echo(struct sk_buff *skb)
823 {
824 struct net *net;
825
826 net = dev_net(skb_dst(skb)->dev);
827 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
828 struct icmp_bxm icmp_param;
829
830 icmp_param.data.icmph = *icmp_hdr(skb);
831 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
832 icmp_param.skb = skb;
833 icmp_param.offset = 0;
834 icmp_param.data_len = skb->len;
835 icmp_param.head_len = sizeof(struct icmphdr);
836 icmp_reply(&icmp_param, skb);
837 }
838 }
839
840 /*
841 * Handle ICMP Timestamp requests.
842 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
843 * SHOULD be in the kernel for minimum random latency.
844 * MUST be accurate to a few minutes.
845 * MUST be updated at least at 15Hz.
846 */
847 static void icmp_timestamp(struct sk_buff *skb)
848 {
849 struct timespec tv;
850 struct icmp_bxm icmp_param;
851 /*
852 * Too short.
853 */
854 if (skb->len < 4)
855 goto out_err;
856
857 /*
858 * Fill in the current time as ms since midnight UT:
859 */
860 getnstimeofday(&tv);
861 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
862 tv.tv_nsec / NSEC_PER_MSEC);
863 icmp_param.data.times[2] = icmp_param.data.times[1];
864 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
865 BUG();
866 icmp_param.data.icmph = *icmp_hdr(skb);
867 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
868 icmp_param.data.icmph.code = 0;
869 icmp_param.skb = skb;
870 icmp_param.offset = 0;
871 icmp_param.data_len = 0;
872 icmp_param.head_len = sizeof(struct icmphdr) + 12;
873 icmp_reply(&icmp_param, skb);
874 out:
875 return;
876 out_err:
877 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
878 goto out;
879 }
880
881
882 /*
883 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
884 *
885 * RFC1122 (3.2.2.9). A host MUST only send replies to
886 * ADDRESS_MASK requests if it's been configured as an address mask
887 * agent. Receiving a request doesn't constitute implicit permission to
888 * act as one. Of course, implementing this correctly requires (SHOULD)
889 * a way to turn the functionality on and off. Another one for sysctl(),
890 * I guess. -- MS
891 *
892 * RFC1812 (4.3.3.9). A router MUST implement it.
893 * A router SHOULD have switch turning it on/off.
894 * This switch MUST be ON by default.
895 *
896 * Gratuitous replies, zero-source replies are not implemented,
897 * that complies with RFC. DO NOT implement them!!! All the idea
898 * of broadcast addrmask replies as specified in RFC950 is broken.
899 * The problem is that it is not uncommon to have several prefixes
900 * on one physical interface. Moreover, addrmask agent can even be
901 * not aware of existing another prefixes.
902 * If source is zero, addrmask agent cannot choose correct prefix.
903 * Gratuitous mask announcements suffer from the same problem.
904 * RFC1812 explains it, but still allows to use ADDRMASK,
905 * that is pretty silly. --ANK
906 *
907 * All these rules are so bizarre, that I removed kernel addrmask
908 * support at all. It is wrong, it is obsolete, nobody uses it in
909 * any case. --ANK
910 *
911 * Furthermore you can do it with a usermode address agent program
912 * anyway...
913 */
914
915 static void icmp_address(struct sk_buff *skb)
916 {
917 #if 0
918 if (net_ratelimit())
919 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
920 #endif
921 }
922
923 /*
924 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
925 * loudly if an inconsistency is found.
926 */
927
928 static void icmp_address_reply(struct sk_buff *skb)
929 {
930 struct rtable *rt = skb_rtable(skb);
931 struct net_device *dev = skb->dev;
932 struct in_device *in_dev;
933 struct in_ifaddr *ifa;
934
935 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
936 goto out;
937
938 in_dev = in_dev_get(dev);
939 if (!in_dev)
940 goto out;
941 rcu_read_lock();
942 if (in_dev->ifa_list &&
943 IN_DEV_LOG_MARTIANS(in_dev) &&
944 IN_DEV_FORWARD(in_dev)) {
945 __be32 _mask, *mp;
946
947 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
948 BUG_ON(mp == NULL);
949 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
950 if (*mp == ifa->ifa_mask &&
951 inet_ifa_match(rt->rt_src, ifa))
952 break;
953 }
954 if (!ifa && net_ratelimit()) {
955 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
956 mp, dev->name, &rt->rt_src);
957 }
958 }
959 rcu_read_unlock();
960 in_dev_put(in_dev);
961 out:;
962 }
963
964 static void icmp_discard(struct sk_buff *skb)
965 {
966 }
967
968 /*
969 * Deal with incoming ICMP packets.
970 */
971 int icmp_rcv(struct sk_buff *skb)
972 {
973 struct icmphdr *icmph;
974 struct rtable *rt = skb_rtable(skb);
975 struct net *net = dev_net(rt->u.dst.dev);
976
977 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
978 struct sec_path *sp = skb_sec_path(skb);
979 int nh;
980
981 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
982 XFRM_STATE_ICMP))
983 goto drop;
984
985 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
986 goto drop;
987
988 nh = skb_network_offset(skb);
989 skb_set_network_header(skb, sizeof(*icmph));
990
991 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
992 goto drop;
993
994 skb_set_network_header(skb, nh);
995 }
996
997 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
998
999 switch (skb->ip_summed) {
1000 case CHECKSUM_COMPLETE:
1001 if (!csum_fold(skb->csum))
1002 break;
1003 /* fall through */
1004 case CHECKSUM_NONE:
1005 skb->csum = 0;
1006 if (__skb_checksum_complete(skb))
1007 goto error;
1008 }
1009
1010 if (!pskb_pull(skb, sizeof(*icmph)))
1011 goto error;
1012
1013 icmph = icmp_hdr(skb);
1014
1015 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1016 /*
1017 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1018 *
1019 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1020 * discarded.
1021 */
1022 if (icmph->type > NR_ICMP_TYPES)
1023 goto error;
1024
1025
1026 /*
1027 * Parse the ICMP message
1028 */
1029
1030 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1031 /*
1032 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1033 * silently ignored (we let user decide with a sysctl).
1034 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1035 * discarded if to broadcast/multicast.
1036 */
1037 if ((icmph->type == ICMP_ECHO ||
1038 icmph->type == ICMP_TIMESTAMP) &&
1039 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1040 goto error;
1041 }
1042 if (icmph->type != ICMP_ECHO &&
1043 icmph->type != ICMP_TIMESTAMP &&
1044 icmph->type != ICMP_ADDRESS &&
1045 icmph->type != ICMP_ADDRESSREPLY) {
1046 goto error;
1047 }
1048 }
1049
1050 icmp_pointers[icmph->type].handler(skb);
1051
1052 drop:
1053 kfree_skb(skb);
1054 return 0;
1055 error:
1056 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1057 goto drop;
1058 }
1059
1060 /*
1061 * This table is the definition of how we handle ICMP.
1062 */
1063 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1064 [ICMP_ECHOREPLY] = {
1065 .handler = icmp_discard,
1066 },
1067 [1] = {
1068 .handler = icmp_discard,
1069 .error = 1,
1070 },
1071 [2] = {
1072 .handler = icmp_discard,
1073 .error = 1,
1074 },
1075 [ICMP_DEST_UNREACH] = {
1076 .handler = icmp_unreach,
1077 .error = 1,
1078 },
1079 [ICMP_SOURCE_QUENCH] = {
1080 .handler = icmp_unreach,
1081 .error = 1,
1082 },
1083 [ICMP_REDIRECT] = {
1084 .handler = icmp_redirect,
1085 .error = 1,
1086 },
1087 [6] = {
1088 .handler = icmp_discard,
1089 .error = 1,
1090 },
1091 [7] = {
1092 .handler = icmp_discard,
1093 .error = 1,
1094 },
1095 [ICMP_ECHO] = {
1096 .handler = icmp_echo,
1097 },
1098 [9] = {
1099 .handler = icmp_discard,
1100 .error = 1,
1101 },
1102 [10] = {
1103 .handler = icmp_discard,
1104 .error = 1,
1105 },
1106 [ICMP_TIME_EXCEEDED] = {
1107 .handler = icmp_unreach,
1108 .error = 1,
1109 },
1110 [ICMP_PARAMETERPROB] = {
1111 .handler = icmp_unreach,
1112 .error = 1,
1113 },
1114 [ICMP_TIMESTAMP] = {
1115 .handler = icmp_timestamp,
1116 },
1117 [ICMP_TIMESTAMPREPLY] = {
1118 .handler = icmp_discard,
1119 },
1120 [ICMP_INFO_REQUEST] = {
1121 .handler = icmp_discard,
1122 },
1123 [ICMP_INFO_REPLY] = {
1124 .handler = icmp_discard,
1125 },
1126 [ICMP_ADDRESS] = {
1127 .handler = icmp_address,
1128 },
1129 [ICMP_ADDRESSREPLY] = {
1130 .handler = icmp_address_reply,
1131 },
1132 };
1133
1134 static void __net_exit icmp_sk_exit(struct net *net)
1135 {
1136 int i;
1137
1138 for_each_possible_cpu(i)
1139 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1140 kfree(net->ipv4.icmp_sk);
1141 net->ipv4.icmp_sk = NULL;
1142 }
1143
1144 static int __net_init icmp_sk_init(struct net *net)
1145 {
1146 int i, err;
1147
1148 net->ipv4.icmp_sk =
1149 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1150 if (net->ipv4.icmp_sk == NULL)
1151 return -ENOMEM;
1152
1153 for_each_possible_cpu(i) {
1154 struct sock *sk;
1155
1156 err = inet_ctl_sock_create(&sk, PF_INET,
1157 SOCK_RAW, IPPROTO_ICMP, net);
1158 if (err < 0)
1159 goto fail;
1160
1161 net->ipv4.icmp_sk[i] = sk;
1162
1163 /* Enough space for 2 64K ICMP packets, including
1164 * sk_buff struct overhead.
1165 */
1166 sk->sk_sndbuf =
1167 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1168
1169 /*
1170 * Speedup sock_wfree()
1171 */
1172 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1173 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1174 }
1175
1176 /* Control parameters for ECHO replies. */
1177 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1178 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1179
1180 /* Control parameter - ignore bogus broadcast responses? */
1181 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1182
1183 /*
1184 * Configurable global rate limit.
1185 *
1186 * ratelimit defines tokens/packet consumed for dst->rate_token
1187 * bucket ratemask defines which icmp types are ratelimited by
1188 * setting it's bit position.
1189 *
1190 * default:
1191 * dest unreachable (3), source quench (4),
1192 * time exceeded (11), parameter problem (12)
1193 */
1194
1195 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1196 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1197 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1198
1199 return 0;
1200
1201 fail:
1202 for_each_possible_cpu(i)
1203 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1204 kfree(net->ipv4.icmp_sk);
1205 return err;
1206 }
1207
1208 static struct pernet_operations __net_initdata icmp_sk_ops = {
1209 .init = icmp_sk_init,
1210 .exit = icmp_sk_exit,
1211 };
1212
1213 int __init icmp_init(void)
1214 {
1215 return register_pernet_subsys(&icmp_sk_ops);
1216 }
1217
1218 EXPORT_SYMBOL(icmp_err_convert);
1219 EXPORT_SYMBOL(icmp_send);
1220 EXPORT_SYMBOL(xrlim_allow);
CRIS linux kernel tree