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thp: fix bad_page to show the real reason the page is bad
[linux/fpc-iii.git] / net / ipv4 / icmp.c
blob4aa1b7f01ea0c18a5718061fe31eee71f4de883f
1 /*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * Some of the function names and the icmp unreach table for this
12 * module were derived from [icmp.c 1.0.11 06/02/93] by
13 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
14 * Other than that this module is a complete rewrite.
15 *
16 * Fixes:
17 * Clemens Fruhwirth : introduce global icmp rate limiting
18 * with icmp type masking ability instead
19 * of broken per type icmp timeouts.
20 * Mike Shaver : RFC1122 checks.
21 * Alan Cox : Multicast ping reply as self.
22 * Alan Cox : Fix atomicity lockup in ip_build_xmit
23 * call.
24 * Alan Cox : Added 216,128 byte paths to the MTU
25 * code.
26 * Martin Mares : RFC1812 checks.
27 * Martin Mares : Can be configured to follow redirects
28 * if acting as a router _without_ a
29 * routing protocol (RFC 1812).
30 * Martin Mares : Echo requests may be configured to
31 * be ignored (RFC 1812).
32 * Martin Mares : Limitation of ICMP error message
33 * transmit rate (RFC 1812).
34 * Martin Mares : TOS and Precedence set correctly
35 * (RFC 1812).
36 * Martin Mares : Now copying as much data from the
37 * original packet as we can without
38 * exceeding 576 bytes (RFC 1812).
39 * Willy Konynenberg : Transparent proxying support.
40 * Keith Owens : RFC1191 correction for 4.2BSD based
41 * path MTU bug.
42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
43 * valid (RFC 1812).
44 * Andi Kleen : Check all packet lengths properly
45 * and moved all kfree_skb() up to
46 * icmp_rcv.
47 * Andi Kleen : Move the rate limit bookkeeping
48 * into the dest entry and use a token
49 * bucket filter (thanks to ANK). Make
50 * the rates sysctl configurable.
51 * Yu Tianli : Fixed two ugly bugs in icmp_send
52 * - IP option length was accounted wrongly
53 * - ICMP header length was not accounted
54 * at all.
55 * Tristan Greaves : Added sysctl option to ignore bogus
56 * broadcast responses from broken routers.
57 *
58 * To Fix:
59 *
60 * - Should use skb_pull() instead of all the manual checking.
61 * This would also greatly simply some upper layer error handlers. --AK
62 *
63 */
64
65 #include <linux/module.h>
66 #include <linux/types.h>
67 #include <linux/jiffies.h>
68 #include <linux/kernel.h>
69 #include <linux/fcntl.h>
70 #include <linux/socket.h>
71 #include <linux/in.h>
72 #include <linux/inet.h>
73 #include <linux/inetdevice.h>
74 #include <linux/netdevice.h>
75 #include <linux/string.h>
76 #include <linux/netfilter_ipv4.h>
77 #include <linux/slab.h>
78 #include <net/snmp.h>
79 #include <net/ip.h>
80 #include <net/route.h>
81 #include <net/protocol.h>
82 #include <net/icmp.h>
83 #include <net/tcp.h>
84 #include <net/udp.h>
85 #include <net/raw.h>
86 #include <linux/skbuff.h>
87 #include <net/sock.h>
88 #include <linux/errno.h>
89 #include <linux/timer.h>
90 #include <linux/init.h>
91 #include <asm/system.h>
92 #include <asm/uaccess.h>
93 #include <net/checksum.h>
94 #include <net/xfrm.h>
95 #include <net/inet_common.h>
96
97 /*
98 * Build xmit assembly blocks
99 */
100
101 struct icmp_bxm {
102 struct sk_buff *skb;
103 int offset;
104 int data_len;
105
106 struct {
107 struct icmphdr icmph;
108 __be32 times[3];
109 } data;
110 int head_len;
111 struct ip_options replyopts;
112 unsigned char optbuf[40];
113 };
114
115 /* An array of errno for error messages from dest unreach. */
116 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
117
118 const struct icmp_err icmp_err_convert[] = {
119 {
120 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
121 .fatal = 0,
122 },
123 {
124 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
125 .fatal = 0,
126 },
127 {
128 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
129 .fatal = 1,
130 },
131 {
132 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
133 .fatal = 1,
134 },
135 {
136 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
137 .fatal = 0,
138 },
139 {
140 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
141 .fatal = 0,
142 },
143 {
144 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
145 .fatal = 1,
146 },
147 {
148 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
149 .fatal = 1,
150 },
151 {
152 .errno = ENONET, /* ICMP_HOST_ISOLATED */
153 .fatal = 1,
154 },
155 {
156 .errno = ENETUNREACH, /* ICMP_NET_ANO */
157 .fatal = 1,
158 },
159 {
160 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
161 .fatal = 1,
162 },
163 {
164 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
165 .fatal = 0,
166 },
167 {
168 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
169 .fatal = 0,
170 },
171 {
172 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
173 .fatal = 1,
174 },
175 {
176 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
177 .fatal = 1,
178 },
179 {
180 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
181 .fatal = 1,
182 },
183 };
184 EXPORT_SYMBOL(icmp_err_convert);
185
186 /*
187 * ICMP control array. This specifies what to do with each ICMP.
188 */
189
190 struct icmp_control {
191 void (*handler)(struct sk_buff *skb);
192 short error; /* This ICMP is classed as an error message */
193 };
194
195 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
196
197 /*
198 * The ICMP socket(s). This is the most convenient way to flow control
199 * our ICMP output as well as maintain a clean interface throughout
200 * all layers. All Socketless IP sends will soon be gone.
201 *
202 * On SMP we have one ICMP socket per-cpu.
203 */
204 static struct sock *icmp_sk(struct net *net)
205 {
206 return net->ipv4.icmp_sk[smp_processor_id()];
207 }
208
209 static inline struct sock *icmp_xmit_lock(struct net *net)
210 {
211 struct sock *sk;
212
213 local_bh_disable();
214
215 sk = icmp_sk(net);
216
217 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
218 /* This can happen if the output path signals a
219 * dst_link_failure() for an outgoing ICMP packet.
220 */
221 local_bh_enable();
222 return NULL;
223 }
224 return sk;
225 }
226
227 static inline void icmp_xmit_unlock(struct sock *sk)
228 {
229 spin_unlock_bh(&sk->sk_lock.slock);
230 }
231
232 /*
233 * Send an ICMP frame.
234 */
235
236 /*
237 * Check transmit rate limitation for given message.
238 * The rate information is held in the destination cache now.
239 * This function is generic and could be used for other purposes
240 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
241 *
242 * Note that the same dst_entry fields are modified by functions in
243 * route.c too, but these work for packet destinations while xrlim_allow
244 * works for icmp destinations. This means the rate limiting information
245 * for one "ip object" is shared - and these ICMPs are twice limited:
246 * by source and by destination.
247 *
248 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
249 * SHOULD allow setting of rate limits
250 *
251 * Shared between ICMPv4 and ICMPv6.
252 */
253 #define XRLIM_BURST_FACTOR 6
254 int xrlim_allow(struct dst_entry *dst, int timeout)
255 {
256 unsigned long now, token = dst->rate_tokens;
257 int rc = 0;
258
259 now = jiffies;
260 token += now - dst->rate_last;
261 dst->rate_last = now;
262 if (token > XRLIM_BURST_FACTOR * timeout)
263 token = XRLIM_BURST_FACTOR * timeout;
264 if (token >= timeout) {
265 token -= timeout;
266 rc = 1;
267 }
268 dst->rate_tokens = token;
269 return rc;
270 }
271 EXPORT_SYMBOL(xrlim_allow);
272
273 static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
274 int type, int code)
275 {
276 struct dst_entry *dst = &rt->dst;
277 int rc = 1;
278
279 if (type > NR_ICMP_TYPES)
280 goto out;
281
282 /* Don't limit PMTU discovery. */
283 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
284 goto out;
285
286 /* No rate limit on loopback */
287 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
288 goto out;
289
290 /* Limit if icmp type is enabled in ratemask. */
291 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
292 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
293 out:
294 return rc;
295 }
296
297 /*
298 * Maintain the counters used in the SNMP statistics for outgoing ICMP
299 */
300 void icmp_out_count(struct net *net, unsigned char type)
301 {
302 ICMPMSGOUT_INC_STATS(net, type);
303 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
304 }
305
306 /*
307 * Checksum each fragment, and on the first include the headers and final
308 * checksum.
309 */
310 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
311 struct sk_buff *skb)
312 {
313 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
314 __wsum csum;
315
316 csum = skb_copy_and_csum_bits(icmp_param->skb,
317 icmp_param->offset + offset,
318 to, len, 0);
319
320 skb->csum = csum_block_add(skb->csum, csum, odd);
321 if (icmp_pointers[icmp_param->data.icmph.type].error)
322 nf_ct_attach(skb, icmp_param->skb);
323 return 0;
324 }
325
326 static void icmp_push_reply(struct icmp_bxm *icmp_param,
327 struct ipcm_cookie *ipc, struct rtable **rt)
328 {
329 struct sock *sk;
330 struct sk_buff *skb;
331
332 sk = icmp_sk(dev_net((*rt)->dst.dev));
333 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
334 icmp_param->data_len+icmp_param->head_len,
335 icmp_param->head_len,
336 ipc, rt, MSG_DONTWAIT) < 0) {
337 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
338 ip_flush_pending_frames(sk);
339 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
340 struct icmphdr *icmph = icmp_hdr(skb);
341 __wsum csum = 0;
342 struct sk_buff *skb1;
343
344 skb_queue_walk(&sk->sk_write_queue, skb1) {
345 csum = csum_add(csum, skb1->csum);
346 }
347 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
348 (char *)icmph,
349 icmp_param->head_len, csum);
350 icmph->checksum = csum_fold(csum);
351 skb->ip_summed = CHECKSUM_NONE;
352 ip_push_pending_frames(sk);
353 }
354 }
355
356 /*
357 * Driving logic for building and sending ICMP messages.
358 */
359
360 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
361 {
362 struct ipcm_cookie ipc;
363 struct rtable *rt = skb_rtable(skb);
364 struct net *net = dev_net(rt->dst.dev);
365 struct sock *sk;
366 struct inet_sock *inet;
367 __be32 daddr;
368
369 if (ip_options_echo(&icmp_param->replyopts, skb))
370 return;
371
372 sk = icmp_xmit_lock(net);
373 if (sk == NULL)
374 return;
375 inet = inet_sk(sk);
376
377 icmp_param->data.icmph.checksum = 0;
378
379 inet->tos = ip_hdr(skb)->tos;
380 daddr = ipc.addr = rt->rt_src;
381 ipc.opt = NULL;
382 ipc.tx_flags = 0;
383 if (icmp_param->replyopts.optlen) {
384 ipc.opt = &icmp_param->replyopts;
385 if (ipc.opt->srr)
386 daddr = icmp_param->replyopts.faddr;
387 }
388 {
389 struct flowi fl = { .fl4_dst= daddr,
390 .fl4_src = rt->rt_spec_dst,
391 .fl4_tos = RT_TOS(ip_hdr(skb)->tos),
392 .proto = IPPROTO_ICMP };
393 security_skb_classify_flow(skb, &fl);
394 if (ip_route_output_key(net, &rt, &fl))
395 goto out_unlock;
396 }
397 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
398 icmp_param->data.icmph.code))
399 icmp_push_reply(icmp_param, &ipc, &rt);
400 ip_rt_put(rt);
401 out_unlock:
402 icmp_xmit_unlock(sk);
403 }
404
405
406 /*
407 * Send an ICMP message in response to a situation
408 *
409 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
410 * MAY send more (we do).
411 * MUST NOT change this header information.
412 * MUST NOT reply to a multicast/broadcast IP address.
413 * MUST NOT reply to a multicast/broadcast MAC address.
414 * MUST reply to only the first fragment.
415 */
416
417 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
418 {
419 struct iphdr *iph;
420 int room;
421 struct icmp_bxm icmp_param;
422 struct rtable *rt = skb_rtable(skb_in);
423 struct ipcm_cookie ipc;
424 __be32 saddr;
425 u8 tos;
426 struct net *net;
427 struct sock *sk;
428
429 if (!rt)
430 goto out;
431 net = dev_net(rt->dst.dev);
432
433 /*
434 * Find the original header. It is expected to be valid, of course.
435 * Check this, icmp_send is called from the most obscure devices
436 * sometimes.
437 */
438 iph = ip_hdr(skb_in);
439
440 if ((u8 *)iph < skb_in->head ||
441 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
442 goto out;
443
444 /*
445 * No replies to physical multicast/broadcast
446 */
447 if (skb_in->pkt_type != PACKET_HOST)
448 goto out;
449
450 /*
451 * Now check at the protocol level
452 */
453 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
454 goto out;
455
456 /*
457 * Only reply to fragment 0. We byte re-order the constant
458 * mask for efficiency.
459 */
460 if (iph->frag_off & htons(IP_OFFSET))
461 goto out;
462
463 /*
464 * If we send an ICMP error to an ICMP error a mess would result..
465 */
466 if (icmp_pointers[type].error) {
467 /*
468 * We are an error, check if we are replying to an
469 * ICMP error
470 */
471 if (iph->protocol == IPPROTO_ICMP) {
472 u8 _inner_type, *itp;
473
474 itp = skb_header_pointer(skb_in,
475 skb_network_header(skb_in) +
476 (iph->ihl << 2) +
477 offsetof(struct icmphdr,
478 type) -
479 skb_in->data,
480 sizeof(_inner_type),
481 &_inner_type);
482 if (itp == NULL)
483 goto out;
484
485 /*
486 * Assume any unknown ICMP type is an error. This
487 * isn't specified by the RFC, but think about it..
488 */
489 if (*itp > NR_ICMP_TYPES ||
490 icmp_pointers[*itp].error)
491 goto out;
492 }
493 }
494
495 sk = icmp_xmit_lock(net);
496 if (sk == NULL)
497 return;
498
499 /*
500 * Construct source address and options.
501 */
502
503 saddr = iph->daddr;
504 if (!(rt->rt_flags & RTCF_LOCAL)) {
505 struct net_device *dev = NULL;
506
507 rcu_read_lock();
508 if (rt_is_input_route(rt) &&
509 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
510 dev = dev_get_by_index_rcu(net, rt->fl.iif);
511
512 if (dev)
513 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
514 else
515 saddr = 0;
516 rcu_read_unlock();
517 }
518
519 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
520 IPTOS_PREC_INTERNETCONTROL) :
521 iph->tos;
522
523 if (ip_options_echo(&icmp_param.replyopts, skb_in))
524 goto out_unlock;
525
526
527 /*
528 * Prepare data for ICMP header.
529 */
530
531 icmp_param.data.icmph.type = type;
532 icmp_param.data.icmph.code = code;
533 icmp_param.data.icmph.un.gateway = info;
534 icmp_param.data.icmph.checksum = 0;
535 icmp_param.skb = skb_in;
536 icmp_param.offset = skb_network_offset(skb_in);
537 inet_sk(sk)->tos = tos;
538 ipc.addr = iph->saddr;
539 ipc.opt = &icmp_param.replyopts;
540 ipc.tx_flags = 0;
541
542 {
543 struct flowi fl = {
544 .fl4_dst = icmp_param.replyopts.srr ?
545 icmp_param.replyopts.faddr : iph->saddr,
546 .fl4_src = saddr,
547 .fl4_tos = RT_TOS(tos),
548 .proto = IPPROTO_ICMP,
549 .fl_icmp_type = type,
550 .fl_icmp_code = code,
551 };
552 int err;
553 struct rtable *rt2;
554
555 security_skb_classify_flow(skb_in, &fl);
556 if (__ip_route_output_key(net, &rt, &fl))
557 goto out_unlock;
558
559 /* No need to clone since we're just using its address. */
560 rt2 = rt;
561
562 if (!fl.nl_u.ip4_u.saddr)
563 fl.nl_u.ip4_u.saddr = rt->rt_src;
564
565 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
566 switch (err) {
567 case 0:
568 if (rt != rt2)
569 goto route_done;
570 break;
571 case -EPERM:
572 rt = NULL;
573 break;
574 default:
575 goto out_unlock;
576 }
577
578 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
579 goto relookup_failed;
580
581 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
582 err = __ip_route_output_key(net, &rt2, &fl);
583 else {
584 struct flowi fl2 = {};
585 unsigned long orefdst;
586
587 fl2.fl4_dst = fl.fl4_src;
588 if (ip_route_output_key(net, &rt2, &fl2))
589 goto relookup_failed;
590
591 /* Ugh! */
592 orefdst = skb_in->_skb_refdst; /* save old refdst */
593 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
594 RT_TOS(tos), rt2->dst.dev);
595
596 dst_release(&rt2->dst);
597 rt2 = skb_rtable(skb_in);
598 skb_in->_skb_refdst = orefdst; /* restore old refdst */
599 }
600
601 if (err)
602 goto relookup_failed;
603
604 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
605 XFRM_LOOKUP_ICMP);
606 switch (err) {
607 case 0:
608 dst_release(&rt->dst);
609 rt = rt2;
610 break;
611 case -EPERM:
612 goto ende;
613 default:
614 relookup_failed:
615 if (!rt)
616 goto out_unlock;
617 break;
618 }
619 }
620
621 route_done:
622 if (!icmpv4_xrlim_allow(net, rt, type, code))
623 goto ende;
624
625 /* RFC says return as much as we can without exceeding 576 bytes. */
626
627 room = dst_mtu(&rt->dst);
628 if (room > 576)
629 room = 576;
630 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
631 room -= sizeof(struct icmphdr);
632
633 icmp_param.data_len = skb_in->len - icmp_param.offset;
634 if (icmp_param.data_len > room)
635 icmp_param.data_len = room;
636 icmp_param.head_len = sizeof(struct icmphdr);
637
638 icmp_push_reply(&icmp_param, &ipc, &rt);
639 ende:
640 ip_rt_put(rt);
641 out_unlock:
642 icmp_xmit_unlock(sk);
643 out:;
644 }
645 EXPORT_SYMBOL(icmp_send);
646
647
648 /*
649 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
650 */
651
652 static void icmp_unreach(struct sk_buff *skb)
653 {
654 struct iphdr *iph;
655 struct icmphdr *icmph;
656 int hash, protocol;
657 const struct net_protocol *ipprot;
658 u32 info = 0;
659 struct net *net;
660
661 net = dev_net(skb_dst(skb)->dev);
662
663 /*
664 * Incomplete header ?
665 * Only checks for the IP header, there should be an
666 * additional check for longer headers in upper levels.
667 */
668
669 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
670 goto out_err;
671
672 icmph = icmp_hdr(skb);
673 iph = (struct iphdr *)skb->data;
674
675 if (iph->ihl < 5) /* Mangled header, drop. */
676 goto out_err;
677
678 if (icmph->type == ICMP_DEST_UNREACH) {
679 switch (icmph->code & 15) {
680 case ICMP_NET_UNREACH:
681 case ICMP_HOST_UNREACH:
682 case ICMP_PROT_UNREACH:
683 case ICMP_PORT_UNREACH:
684 break;
685 case ICMP_FRAG_NEEDED:
686 if (ipv4_config.no_pmtu_disc) {
687 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
688 &iph->daddr);
689 } else {
690 info = ip_rt_frag_needed(net, iph,
691 ntohs(icmph->un.frag.mtu),
692 skb->dev);
693 if (!info)
694 goto out;
695 }
696 break;
697 case ICMP_SR_FAILED:
698 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
699 &iph->daddr);
700 break;
701 default:
702 break;
703 }
704 if (icmph->code > NR_ICMP_UNREACH)
705 goto out;
706 } else if (icmph->type == ICMP_PARAMETERPROB)
707 info = ntohl(icmph->un.gateway) >> 24;
708
709 /*
710 * Throw it at our lower layers
711 *
712 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
713 * header.
714 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
715 * transport layer.
716 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
717 * transport layer.
718 */
719
720 /*
721 * Check the other end isnt violating RFC 1122. Some routers send
722 * bogus responses to broadcast frames. If you see this message
723 * first check your netmask matches at both ends, if it does then
724 * get the other vendor to fix their kit.
725 */
726
727 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
728 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
729 if (net_ratelimit())
730 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
731 "type %u, code %u "
732 "error to a broadcast: %pI4 on %s\n",
733 &ip_hdr(skb)->saddr,
734 icmph->type, icmph->code,
735 &iph->daddr,
736 skb->dev->name);
737 goto out;
738 }
739
740 /* Checkin full IP header plus 8 bytes of protocol to
741 * avoid additional coding at protocol handlers.
742 */
743 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
744 goto out;
745
746 iph = (struct iphdr *)skb->data;
747 protocol = iph->protocol;
748
749 /*
750 * Deliver ICMP message to raw sockets. Pretty useless feature?
751 */
752 raw_icmp_error(skb, protocol, info);
753
754 hash = protocol & (MAX_INET_PROTOS - 1);
755 rcu_read_lock();
756 ipprot = rcu_dereference(inet_protos[hash]);
757 if (ipprot && ipprot->err_handler)
758 ipprot->err_handler(skb, info);
759 rcu_read_unlock();
760
761 out:
762 return;
763 out_err:
764 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
765 goto out;
766 }
767
768
769 /*
770 * Handle ICMP_REDIRECT.
771 */
772
773 static void icmp_redirect(struct sk_buff *skb)
774 {
775 struct iphdr *iph;
776
777 if (skb->len < sizeof(struct iphdr))
778 goto out_err;
779
780 /*
781 * Get the copied header of the packet that caused the redirect
782 */
783 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
784 goto out;
785
786 iph = (struct iphdr *)skb->data;
787
788 switch (icmp_hdr(skb)->code & 7) {
789 case ICMP_REDIR_NET:
790 case ICMP_REDIR_NETTOS:
791 /*
792 * As per RFC recommendations now handle it as a host redirect.
793 */
794 case ICMP_REDIR_HOST:
795 case ICMP_REDIR_HOSTTOS:
796 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
797 icmp_hdr(skb)->un.gateway,
798 iph->saddr, skb->dev);
799 break;
800 }
801 out:
802 return;
803 out_err:
804 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
805 goto out;
806 }
807
808 /*
809 * Handle ICMP_ECHO ("ping") requests.
810 *
811 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
812 * requests.
813 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
814 * included in the reply.
815 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
816 * echo requests, MUST have default=NOT.
817 * See also WRT handling of options once they are done and working.
818 */
819
820 static void icmp_echo(struct sk_buff *skb)
821 {
822 struct net *net;
823
824 net = dev_net(skb_dst(skb)->dev);
825 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
826 struct icmp_bxm icmp_param;
827
828 icmp_param.data.icmph = *icmp_hdr(skb);
829 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
830 icmp_param.skb = skb;
831 icmp_param.offset = 0;
832 icmp_param.data_len = skb->len;
833 icmp_param.head_len = sizeof(struct icmphdr);
834 icmp_reply(&icmp_param, skb);
835 }
836 }
837
838 /*
839 * Handle ICMP Timestamp requests.
840 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
841 * SHOULD be in the kernel for minimum random latency.
842 * MUST be accurate to a few minutes.
843 * MUST be updated at least at 15Hz.
844 */
845 static void icmp_timestamp(struct sk_buff *skb)
846 {
847 struct timespec tv;
848 struct icmp_bxm icmp_param;
849 /*
850 * Too short.
851 */
852 if (skb->len < 4)
853 goto out_err;
854
855 /*
856 * Fill in the current time as ms since midnight UT:
857 */
858 getnstimeofday(&tv);
859 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
860 tv.tv_nsec / NSEC_PER_MSEC);
861 icmp_param.data.times[2] = icmp_param.data.times[1];
862 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
863 BUG();
864 icmp_param.data.icmph = *icmp_hdr(skb);
865 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
866 icmp_param.data.icmph.code = 0;
867 icmp_param.skb = skb;
868 icmp_param.offset = 0;
869 icmp_param.data_len = 0;
870 icmp_param.head_len = sizeof(struct icmphdr) + 12;
871 icmp_reply(&icmp_param, skb);
872 out:
873 return;
874 out_err:
875 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
876 goto out;
877 }
878
879
880 /*
881 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
882 *
883 * RFC1122 (3.2.2.9). A host MUST only send replies to
884 * ADDRESS_MASK requests if it's been configured as an address mask
885 * agent. Receiving a request doesn't constitute implicit permission to
886 * act as one. Of course, implementing this correctly requires (SHOULD)
887 * a way to turn the functionality on and off. Another one for sysctl(),
888 * I guess. -- MS
889 *
890 * RFC1812 (4.3.3.9). A router MUST implement it.
891 * A router SHOULD have switch turning it on/off.
892 * This switch MUST be ON by default.
893 *
894 * Gratuitous replies, zero-source replies are not implemented,
895 * that complies with RFC. DO NOT implement them!!! All the idea
896 * of broadcast addrmask replies as specified in RFC950 is broken.
897 * The problem is that it is not uncommon to have several prefixes
898 * on one physical interface. Moreover, addrmask agent can even be
899 * not aware of existing another prefixes.
900 * If source is zero, addrmask agent cannot choose correct prefix.
901 * Gratuitous mask announcements suffer from the same problem.
902 * RFC1812 explains it, but still allows to use ADDRMASK,
903 * that is pretty silly. --ANK
904 *
905 * All these rules are so bizarre, that I removed kernel addrmask
906 * support at all. It is wrong, it is obsolete, nobody uses it in
907 * any case. --ANK
908 *
909 * Furthermore you can do it with a usermode address agent program
910 * anyway...
911 */
912
913 static void icmp_address(struct sk_buff *skb)
914 {
915 #if 0
916 if (net_ratelimit())
917 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
918 #endif
919 }
920
921 /*
922 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
923 * loudly if an inconsistency is found.
924 * called with rcu_read_lock()
925 */
926
927 static void icmp_address_reply(struct sk_buff *skb)
928 {
929 struct rtable *rt = skb_rtable(skb);
930 struct net_device *dev = skb->dev;
931 struct in_device *in_dev;
932 struct in_ifaddr *ifa;
933
934 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
935 return;
936
937 in_dev = __in_dev_get_rcu(dev);
938 if (!in_dev)
939 return;
940
941 if (in_dev->ifa_list &&
942 IN_DEV_LOG_MARTIANS(in_dev) &&
943 IN_DEV_FORWARD(in_dev)) {
944 __be32 _mask, *mp;
945
946 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
947 BUG_ON(mp == NULL);
948 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
949 if (*mp == ifa->ifa_mask &&
950 inet_ifa_match(rt->rt_src, ifa))
951 break;
952 }
953 if (!ifa && net_ratelimit()) {
954 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
955 mp, dev->name, &rt->rt_src);
956 }
957 }
958 }
959
960 static void icmp_discard(struct sk_buff *skb)
961 {
962 }
963
964 /*
965 * Deal with incoming ICMP packets.
966 */
967 int icmp_rcv(struct sk_buff *skb)
968 {
969 struct icmphdr *icmph;
970 struct rtable *rt = skb_rtable(skb);
971 struct net *net = dev_net(rt->dst.dev);
972
973 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
974 struct sec_path *sp = skb_sec_path(skb);
975 int nh;
976
977 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
978 XFRM_STATE_ICMP))
979 goto drop;
980
981 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
982 goto drop;
983
984 nh = skb_network_offset(skb);
985 skb_set_network_header(skb, sizeof(*icmph));
986
987 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
988 goto drop;
989
990 skb_set_network_header(skb, nh);
991 }
992
993 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
994
995 switch (skb->ip_summed) {
996 case CHECKSUM_COMPLETE:
997 if (!csum_fold(skb->csum))
998 break;
999 /* fall through */
1000 case CHECKSUM_NONE:
1001 skb->csum = 0;
1002 if (__skb_checksum_complete(skb))
1003 goto error;
1004 }
1005
1006 if (!pskb_pull(skb, sizeof(*icmph)))
1007 goto error;
1008
1009 icmph = icmp_hdr(skb);
1010
1011 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1012 /*
1013 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1014 *
1015 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1016 * discarded.
1017 */
1018 if (icmph->type > NR_ICMP_TYPES)
1019 goto error;
1020
1021
1022 /*
1023 * Parse the ICMP message
1024 */
1025
1026 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1027 /*
1028 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1029 * silently ignored (we let user decide with a sysctl).
1030 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1031 * discarded if to broadcast/multicast.
1032 */
1033 if ((icmph->type == ICMP_ECHO ||
1034 icmph->type == ICMP_TIMESTAMP) &&
1035 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1036 goto error;
1037 }
1038 if (icmph->type != ICMP_ECHO &&
1039 icmph->type != ICMP_TIMESTAMP &&
1040 icmph->type != ICMP_ADDRESS &&
1041 icmph->type != ICMP_ADDRESSREPLY) {
1042 goto error;
1043 }
1044 }
1045
1046 icmp_pointers[icmph->type].handler(skb);
1047
1048 drop:
1049 kfree_skb(skb);
1050 return 0;
1051 error:
1052 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1053 goto drop;
1054 }
1055
1056 /*
1057 * This table is the definition of how we handle ICMP.
1058 */
1059 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1060 [ICMP_ECHOREPLY] = {
1061 .handler = icmp_discard,
1062 },
1063 [1] = {
1064 .handler = icmp_discard,
1065 .error = 1,
1066 },
1067 [2] = {
1068 .handler = icmp_discard,
1069 .error = 1,
1070 },
1071 [ICMP_DEST_UNREACH] = {
1072 .handler = icmp_unreach,
1073 .error = 1,
1074 },
1075 [ICMP_SOURCE_QUENCH] = {
1076 .handler = icmp_unreach,
1077 .error = 1,
1078 },
1079 [ICMP_REDIRECT] = {
1080 .handler = icmp_redirect,
1081 .error = 1,
1082 },
1083 [6] = {
1084 .handler = icmp_discard,
1085 .error = 1,
1086 },
1087 [7] = {
1088 .handler = icmp_discard,
1089 .error = 1,
1090 },
1091 [ICMP_ECHO] = {
1092 .handler = icmp_echo,
1093 },
1094 [9] = {
1095 .handler = icmp_discard,
1096 .error = 1,
1097 },
1098 [10] = {
1099 .handler = icmp_discard,
1100 .error = 1,
1101 },
1102 [ICMP_TIME_EXCEEDED] = {
1103 .handler = icmp_unreach,
1104 .error = 1,
1105 },
1106 [ICMP_PARAMETERPROB] = {
1107 .handler = icmp_unreach,
1108 .error = 1,
1109 },
1110 [ICMP_TIMESTAMP] = {
1111 .handler = icmp_timestamp,
1112 },
1113 [ICMP_TIMESTAMPREPLY] = {
1114 .handler = icmp_discard,
1115 },
1116 [ICMP_INFO_REQUEST] = {
1117 .handler = icmp_discard,
1118 },
1119 [ICMP_INFO_REPLY] = {
1120 .handler = icmp_discard,
1121 },
1122 [ICMP_ADDRESS] = {
1123 .handler = icmp_address,
1124 },
1125 [ICMP_ADDRESSREPLY] = {
1126 .handler = icmp_address_reply,
1127 },
1128 };
1129
1130 static void __net_exit icmp_sk_exit(struct net *net)
1131 {
1132 int i;
1133
1134 for_each_possible_cpu(i)
1135 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1136 kfree(net->ipv4.icmp_sk);
1137 net->ipv4.icmp_sk = NULL;
1138 }
1139
1140 static int __net_init icmp_sk_init(struct net *net)
1141 {
1142 int i, err;
1143
1144 net->ipv4.icmp_sk =
1145 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1146 if (net->ipv4.icmp_sk == NULL)
1147 return -ENOMEM;
1148
1149 for_each_possible_cpu(i) {
1150 struct sock *sk;
1151
1152 err = inet_ctl_sock_create(&sk, PF_INET,
1153 SOCK_RAW, IPPROTO_ICMP, net);
1154 if (err < 0)
1155 goto fail;
1156
1157 net->ipv4.icmp_sk[i] = sk;
1158
1159 /* Enough space for 2 64K ICMP packets, including
1160 * sk_buff struct overhead.
1161 */
1162 sk->sk_sndbuf =
1163 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1164
1165 /*
1166 * Speedup sock_wfree()
1167 */
1168 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1169 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1170 }
1171
1172 /* Control parameters for ECHO replies. */
1173 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1174 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1175
1176 /* Control parameter - ignore bogus broadcast responses? */
1177 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1178
1179 /*
1180 * Configurable global rate limit.
1181 *
1182 * ratelimit defines tokens/packet consumed for dst->rate_token
1183 * bucket ratemask defines which icmp types are ratelimited by
1184 * setting it's bit position.
1185 *
1186 * default:
1187 * dest unreachable (3), source quench (4),
1188 * time exceeded (11), parameter problem (12)
1189 */
1190
1191 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1192 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1193 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1194
1195 return 0;
1196
1197 fail:
1198 for_each_possible_cpu(i)
1199 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1200 kfree(net->ipv4.icmp_sk);
1201 return err;
1202 }
1203
1204 static struct pernet_operations __net_initdata icmp_sk_ops = {
1205 .init = icmp_sk_init,
1206 .exit = icmp_sk_exit,
1207 };
1208
1209 int __init icmp_init(void)
1210 {
1211 return register_pernet_subsys(&icmp_sk_ops);
1212 }
Linux with added FPC-III support