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Fix build on COMPAT platforms when CONFIG_EPOLL is disabled
[linux-2.6/btrfs-unstable.git] / net / ipv4 / icmp.c
blob860558633b2c28b0ae9e8f658846d0b0bbe2b49b
1 /*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@redhat.com>
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 int icmp_xmit_lock(struct sock *sk)
208 {
209 local_bh_disable();
210
211 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
212 /* This can happen if the output path signals a
213 * dst_link_failure() for an outgoing ICMP packet.
214 */
215 local_bh_enable();
216 return 1;
217 }
218 return 0;
219 }
220
221 static inline void icmp_xmit_unlock(struct sock *sk)
222 {
223 spin_unlock_bh(&sk->sk_lock.slock);
224 }
225
226 /*
227 * Send an ICMP frame.
228 */
229
230 /*
231 * Check transmit rate limitation for given message.
232 * The rate information is held in the destination cache now.
233 * This function is generic and could be used for other purposes
234 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
235 *
236 * Note that the same dst_entry fields are modified by functions in
237 * route.c too, but these work for packet destinations while xrlim_allow
238 * works for icmp destinations. This means the rate limiting information
239 * for one "ip object" is shared - and these ICMPs are twice limited:
240 * by source and by destination.
241 *
242 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
243 * SHOULD allow setting of rate limits
244 *
245 * Shared between ICMPv4 and ICMPv6.
246 */
247 #define XRLIM_BURST_FACTOR 6
248 int xrlim_allow(struct dst_entry *dst, int timeout)
249 {
250 unsigned long now, token = dst->rate_tokens;
251 int rc = 0;
252
253 now = jiffies;
254 token += now - dst->rate_last;
255 dst->rate_last = now;
256 if (token > XRLIM_BURST_FACTOR * timeout)
257 token = XRLIM_BURST_FACTOR * timeout;
258 if (token >= timeout) {
259 token -= timeout;
260 rc = 1;
261 }
262 dst->rate_tokens = token;
263 return rc;
264 }
265
266 static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
267 int type, int code)
268 {
269 struct dst_entry *dst = &rt->u.dst;
270 int rc = 1;
271
272 if (type > NR_ICMP_TYPES)
273 goto out;
274
275 /* Don't limit PMTU discovery. */
276 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
277 goto out;
278
279 /* No rate limit on loopback */
280 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
281 goto out;
282
283 /* Limit if icmp type is enabled in ratemask. */
284 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
285 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
286 out:
287 return rc;
288 }
289
290 /*
291 * Maintain the counters used in the SNMP statistics for outgoing ICMP
292 */
293 void icmp_out_count(struct net *net, unsigned char type)
294 {
295 ICMPMSGOUT_INC_STATS(net, type);
296 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
297 }
298
299 /*
300 * Checksum each fragment, and on the first include the headers and final
301 * checksum.
302 */
303 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
304 struct sk_buff *skb)
305 {
306 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
307 __wsum csum;
308
309 csum = skb_copy_and_csum_bits(icmp_param->skb,
310 icmp_param->offset + offset,
311 to, len, 0);
312
313 skb->csum = csum_block_add(skb->csum, csum, odd);
314 if (icmp_pointers[icmp_param->data.icmph.type].error)
315 nf_ct_attach(skb, icmp_param->skb);
316 return 0;
317 }
318
319 static void icmp_push_reply(struct icmp_bxm *icmp_param,
320 struct ipcm_cookie *ipc, struct rtable *rt)
321 {
322 struct sock *sk;
323 struct sk_buff *skb;
324
325 sk = icmp_sk(dev_net(rt->u.dst.dev));
326 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
327 icmp_param->data_len+icmp_param->head_len,
328 icmp_param->head_len,
329 ipc, rt, MSG_DONTWAIT) < 0)
330 ip_flush_pending_frames(sk);
331 else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
332 struct icmphdr *icmph = icmp_hdr(skb);
333 __wsum csum = 0;
334 struct sk_buff *skb1;
335
336 skb_queue_walk(&sk->sk_write_queue, skb1) {
337 csum = csum_add(csum, skb1->csum);
338 }
339 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
340 (char *)icmph,
341 icmp_param->head_len, csum);
342 icmph->checksum = csum_fold(csum);
343 skb->ip_summed = CHECKSUM_NONE;
344 ip_push_pending_frames(sk);
345 }
346 }
347
348 /*
349 * Driving logic for building and sending ICMP messages.
350 */
351
352 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
353 {
354 struct ipcm_cookie ipc;
355 struct rtable *rt = skb->rtable;
356 struct net *net = dev_net(rt->u.dst.dev);
357 struct sock *sk = icmp_sk(net);
358 struct inet_sock *inet = inet_sk(sk);
359 __be32 daddr;
360
361 if (ip_options_echo(&icmp_param->replyopts, skb))
362 return;
363
364 if (icmp_xmit_lock(sk))
365 return;
366
367 icmp_param->data.icmph.checksum = 0;
368
369 inet->tos = ip_hdr(skb)->tos;
370 daddr = ipc.addr = rt->rt_src;
371 ipc.opt = NULL;
372 if (icmp_param->replyopts.optlen) {
373 ipc.opt = &icmp_param->replyopts;
374 if (ipc.opt->srr)
375 daddr = icmp_param->replyopts.faddr;
376 }
377 {
378 struct flowi fl = { .nl_u = { .ip4_u =
379 { .daddr = daddr,
380 .saddr = rt->rt_spec_dst,
381 .tos = RT_TOS(ip_hdr(skb)->tos) } },
382 .proto = IPPROTO_ICMP };
383 security_skb_classify_flow(skb, &fl);
384 if (ip_route_output_key(net, &rt, &fl))
385 goto out_unlock;
386 }
387 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
388 icmp_param->data.icmph.code))
389 icmp_push_reply(icmp_param, &ipc, rt);
390 ip_rt_put(rt);
391 out_unlock:
392 icmp_xmit_unlock(sk);
393 }
394
395
396 /*
397 * Send an ICMP message in response to a situation
398 *
399 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
400 * MAY send more (we do).
401 * MUST NOT change this header information.
402 * MUST NOT reply to a multicast/broadcast IP address.
403 * MUST NOT reply to a multicast/broadcast MAC address.
404 * MUST reply to only the first fragment.
405 */
406
407 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
408 {
409 struct iphdr *iph;
410 int room;
411 struct icmp_bxm icmp_param;
412 struct rtable *rt = skb_in->rtable;
413 struct ipcm_cookie ipc;
414 __be32 saddr;
415 u8 tos;
416 struct net *net;
417 struct sock *sk;
418
419 if (!rt)
420 goto out;
421 net = dev_net(rt->u.dst.dev);
422 sk = icmp_sk(net);
423
424 /*
425 * Find the original header. It is expected to be valid, of course.
426 * Check this, icmp_send is called from the most obscure devices
427 * sometimes.
428 */
429 iph = ip_hdr(skb_in);
430
431 if ((u8 *)iph < skb_in->head ||
432 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
433 goto out;
434
435 /*
436 * No replies to physical multicast/broadcast
437 */
438 if (skb_in->pkt_type != PACKET_HOST)
439 goto out;
440
441 /*
442 * Now check at the protocol level
443 */
444 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
445 goto out;
446
447 /*
448 * Only reply to fragment 0. We byte re-order the constant
449 * mask for efficiency.
450 */
451 if (iph->frag_off & htons(IP_OFFSET))
452 goto out;
453
454 /*
455 * If we send an ICMP error to an ICMP error a mess would result..
456 */
457 if (icmp_pointers[type].error) {
458 /*
459 * We are an error, check if we are replying to an
460 * ICMP error
461 */
462 if (iph->protocol == IPPROTO_ICMP) {
463 u8 _inner_type, *itp;
464
465 itp = skb_header_pointer(skb_in,
466 skb_network_header(skb_in) +
467 (iph->ihl << 2) +
468 offsetof(struct icmphdr,
469 type) -
470 skb_in->data,
471 sizeof(_inner_type),
472 &_inner_type);
473 if (itp == NULL)
474 goto out;
475
476 /*
477 * Assume any unknown ICMP type is an error. This
478 * isn't specified by the RFC, but think about it..
479 */
480 if (*itp > NR_ICMP_TYPES ||
481 icmp_pointers[*itp].error)
482 goto out;
483 }
484 }
485
486 if (icmp_xmit_lock(sk))
487 return;
488
489 /*
490 * Construct source address and options.
491 */
492
493 saddr = iph->daddr;
494 if (!(rt->rt_flags & RTCF_LOCAL)) {
495 struct net_device *dev = NULL;
496
497 if (rt->fl.iif &&
498 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
499 dev = dev_get_by_index(net, rt->fl.iif);
500
501 if (dev) {
502 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
503 dev_put(dev);
504 } else
505 saddr = 0;
506 }
507
508 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
509 IPTOS_PREC_INTERNETCONTROL) :
510 iph->tos;
511
512 if (ip_options_echo(&icmp_param.replyopts, skb_in))
513 goto out_unlock;
514
515
516 /*
517 * Prepare data for ICMP header.
518 */
519
520 icmp_param.data.icmph.type = type;
521 icmp_param.data.icmph.code = code;
522 icmp_param.data.icmph.un.gateway = info;
523 icmp_param.data.icmph.checksum = 0;
524 icmp_param.skb = skb_in;
525 icmp_param.offset = skb_network_offset(skb_in);
526 inet_sk(sk)->tos = tos;
527 ipc.addr = iph->saddr;
528 ipc.opt = &icmp_param.replyopts;
529
530 {
531 struct flowi fl = {
532 .nl_u = {
533 .ip4_u = {
534 .daddr = icmp_param.replyopts.srr ?
535 icmp_param.replyopts.faddr :
536 iph->saddr,
537 .saddr = saddr,
538 .tos = RT_TOS(tos)
539 }
540 },
541 .proto = IPPROTO_ICMP,
542 .uli_u = {
543 .icmpt = {
544 .type = type,
545 .code = code
546 }
547 }
548 };
549 int err;
550 struct rtable *rt2;
551
552 security_skb_classify_flow(skb_in, &fl);
553 if (__ip_route_output_key(net, &rt, &fl))
554 goto out_unlock;
555
556 /* No need to clone since we're just using its address. */
557 rt2 = rt;
558
559 err = xfrm_lookup((struct dst_entry **)&rt, &fl, NULL, 0);
560 switch (err) {
561 case 0:
562 if (rt != rt2)
563 goto route_done;
564 break;
565 case -EPERM:
566 rt = NULL;
567 break;
568 default:
569 goto out_unlock;
570 }
571
572 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
573 goto relookup_failed;
574
575 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
576 err = __ip_route_output_key(net, &rt2, &fl);
577 else {
578 struct flowi fl2 = {};
579 struct dst_entry *odst;
580
581 fl2.fl4_dst = fl.fl4_src;
582 if (ip_route_output_key(net, &rt2, &fl2))
583 goto relookup_failed;
584
585 /* Ugh! */
586 odst = skb_in->dst;
587 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
588 RT_TOS(tos), rt2->u.dst.dev);
589
590 dst_release(&rt2->u.dst);
591 rt2 = skb_in->rtable;
592 skb_in->dst = odst;
593 }
594
595 if (err)
596 goto relookup_failed;
597
598 err = xfrm_lookup((struct dst_entry **)&rt2, &fl, NULL,
599 XFRM_LOOKUP_ICMP);
600 switch (err) {
601 case 0:
602 dst_release(&rt->u.dst);
603 rt = rt2;
604 break;
605 case -EPERM:
606 goto ende;
607 default:
608 relookup_failed:
609 if (!rt)
610 goto out_unlock;
611 break;
612 }
613 }
614
615 route_done:
616 if (!icmpv4_xrlim_allow(net, rt, type, code))
617 goto ende;
618
619 /* RFC says return as much as we can without exceeding 576 bytes. */
620
621 room = dst_mtu(&rt->u.dst);
622 if (room > 576)
623 room = 576;
624 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
625 room -= sizeof(struct icmphdr);
626
627 icmp_param.data_len = skb_in->len - icmp_param.offset;
628 if (icmp_param.data_len > room)
629 icmp_param.data_len = room;
630 icmp_param.head_len = sizeof(struct icmphdr);
631
632 icmp_push_reply(&icmp_param, &ipc, rt);
633 ende:
634 ip_rt_put(rt);
635 out_unlock:
636 icmp_xmit_unlock(sk);
637 out:;
638 }
639
640
641 /*
642 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
643 */
644
645 static void icmp_unreach(struct sk_buff *skb)
646 {
647 struct iphdr *iph;
648 struct icmphdr *icmph;
649 int hash, protocol;
650 struct net_protocol *ipprot;
651 u32 info = 0;
652 struct net *net;
653
654 net = dev_net(skb->dst->dev);
655
656 /*
657 * Incomplete header ?
658 * Only checks for the IP header, there should be an
659 * additional check for longer headers in upper levels.
660 */
661
662 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
663 goto out_err;
664
665 icmph = icmp_hdr(skb);
666 iph = (struct iphdr *)skb->data;
667
668 if (iph->ihl < 5) /* Mangled header, drop. */
669 goto out_err;
670
671 if (icmph->type == ICMP_DEST_UNREACH) {
672 switch (icmph->code & 15) {
673 case ICMP_NET_UNREACH:
674 case ICMP_HOST_UNREACH:
675 case ICMP_PROT_UNREACH:
676 case ICMP_PORT_UNREACH:
677 break;
678 case ICMP_FRAG_NEEDED:
679 if (ipv4_config.no_pmtu_disc) {
680 LIMIT_NETDEBUG(KERN_INFO "ICMP: " NIPQUAD_FMT ": "
681 "fragmentation needed "
682 "and DF set.\n",
683 NIPQUAD(iph->daddr));
684 } else {
685 info = ip_rt_frag_needed(net, iph,
686 ntohs(icmph->un.frag.mtu),
687 skb->dev);
688 if (!info)
689 goto out;
690 }
691 break;
692 case ICMP_SR_FAILED:
693 LIMIT_NETDEBUG(KERN_INFO "ICMP: " NIPQUAD_FMT ": Source "
694 "Route Failed.\n",
695 NIPQUAD(iph->daddr));
696 break;
697 default:
698 break;
699 }
700 if (icmph->code > NR_ICMP_UNREACH)
701 goto out;
702 } else if (icmph->type == ICMP_PARAMETERPROB)
703 info = ntohl(icmph->un.gateway) >> 24;
704
705 /*
706 * Throw it at our lower layers
707 *
708 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
709 * header.
710 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
711 * transport layer.
712 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
713 * transport layer.
714 */
715
716 /*
717 * Check the other end isnt violating RFC 1122. Some routers send
718 * bogus responses to broadcast frames. If you see this message
719 * first check your netmask matches at both ends, if it does then
720 * get the other vendor to fix their kit.
721 */
722
723 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
724 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
725 if (net_ratelimit())
726 printk(KERN_WARNING NIPQUAD_FMT " sent an invalid ICMP "
727 "type %u, code %u "
728 "error to a broadcast: " NIPQUAD_FMT " on %s\n",
729 NIPQUAD(ip_hdr(skb)->saddr),
730 icmph->type, icmph->code,
731 NIPQUAD(iph->daddr),
732 skb->dev->name);
733 goto out;
734 }
735
736 /* Checkin full IP header plus 8 bytes of protocol to
737 * avoid additional coding at protocol handlers.
738 */
739 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
740 goto out;
741
742 iph = (struct iphdr *)skb->data;
743 protocol = iph->protocol;
744
745 /*
746 * Deliver ICMP message to raw sockets. Pretty useless feature?
747 */
748 raw_icmp_error(skb, protocol, info);
749
750 hash = protocol & (MAX_INET_PROTOS - 1);
751 rcu_read_lock();
752 ipprot = rcu_dereference(inet_protos[hash]);
753 if (ipprot && ipprot->err_handler)
754 ipprot->err_handler(skb, info);
755 rcu_read_unlock();
756
757 out:
758 return;
759 out_err:
760 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
761 goto out;
762 }
763
764
765 /*
766 * Handle ICMP_REDIRECT.
767 */
768
769 static void icmp_redirect(struct sk_buff *skb)
770 {
771 struct iphdr *iph;
772
773 if (skb->len < sizeof(struct iphdr))
774 goto out_err;
775
776 /*
777 * Get the copied header of the packet that caused the redirect
778 */
779 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
780 goto out;
781
782 iph = (struct iphdr *)skb->data;
783
784 switch (icmp_hdr(skb)->code & 7) {
785 case ICMP_REDIR_NET:
786 case ICMP_REDIR_NETTOS:
787 /*
788 * As per RFC recommendations now handle it as a host redirect.
789 */
790 case ICMP_REDIR_HOST:
791 case ICMP_REDIR_HOSTTOS:
792 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
793 icmp_hdr(skb)->un.gateway,
794 iph->saddr, skb->dev);
795 break;
796 }
797 out:
798 return;
799 out_err:
800 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
801 goto out;
802 }
803
804 /*
805 * Handle ICMP_ECHO ("ping") requests.
806 *
807 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
808 * requests.
809 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
810 * included in the reply.
811 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
812 * echo requests, MUST have default=NOT.
813 * See also WRT handling of options once they are done and working.
814 */
815
816 static void icmp_echo(struct sk_buff *skb)
817 {
818 struct net *net;
819
820 net = dev_net(skb->dst->dev);
821 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
822 struct icmp_bxm icmp_param;
823
824 icmp_param.data.icmph = *icmp_hdr(skb);
825 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
826 icmp_param.skb = skb;
827 icmp_param.offset = 0;
828 icmp_param.data_len = skb->len;
829 icmp_param.head_len = sizeof(struct icmphdr);
830 icmp_reply(&icmp_param, skb);
831 }
832 }
833
834 /*
835 * Handle ICMP Timestamp requests.
836 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
837 * SHOULD be in the kernel for minimum random latency.
838 * MUST be accurate to a few minutes.
839 * MUST be updated at least at 15Hz.
840 */
841 static void icmp_timestamp(struct sk_buff *skb)
842 {
843 struct timespec tv;
844 struct icmp_bxm icmp_param;
845 /*
846 * Too short.
847 */
848 if (skb->len < 4)
849 goto out_err;
850
851 /*
852 * Fill in the current time as ms since midnight UT:
853 */
854 getnstimeofday(&tv);
855 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
856 tv.tv_nsec / NSEC_PER_MSEC);
857 icmp_param.data.times[2] = icmp_param.data.times[1];
858 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
859 BUG();
860 icmp_param.data.icmph = *icmp_hdr(skb);
861 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
862 icmp_param.data.icmph.code = 0;
863 icmp_param.skb = skb;
864 icmp_param.offset = 0;
865 icmp_param.data_len = 0;
866 icmp_param.head_len = sizeof(struct icmphdr) + 12;
867 icmp_reply(&icmp_param, skb);
868 out:
869 return;
870 out_err:
871 ICMP_INC_STATS_BH(dev_net(skb->dst->dev), ICMP_MIB_INERRORS);
872 goto out;
873 }
874
875
876 /*
877 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
878 *
879 * RFC1122 (3.2.2.9). A host MUST only send replies to
880 * ADDRESS_MASK requests if it's been configured as an address mask
881 * agent. Receiving a request doesn't constitute implicit permission to
882 * act as one. Of course, implementing this correctly requires (SHOULD)
883 * a way to turn the functionality on and off. Another one for sysctl(),
884 * I guess. -- MS
885 *
886 * RFC1812 (4.3.3.9). A router MUST implement it.
887 * A router SHOULD have switch turning it on/off.
888 * This switch MUST be ON by default.
889 *
890 * Gratuitous replies, zero-source replies are not implemented,
891 * that complies with RFC. DO NOT implement them!!! All the idea
892 * of broadcast addrmask replies as specified in RFC950 is broken.
893 * The problem is that it is not uncommon to have several prefixes
894 * on one physical interface. Moreover, addrmask agent can even be
895 * not aware of existing another prefixes.
896 * If source is zero, addrmask agent cannot choose correct prefix.
897 * Gratuitous mask announcements suffer from the same problem.
898 * RFC1812 explains it, but still allows to use ADDRMASK,
899 * that is pretty silly. --ANK
900 *
901 * All these rules are so bizarre, that I removed kernel addrmask
902 * support at all. It is wrong, it is obsolete, nobody uses it in
903 * any case. --ANK
904 *
905 * Furthermore you can do it with a usermode address agent program
906 * anyway...
907 */
908
909 static void icmp_address(struct sk_buff *skb)
910 {
911 #if 0
912 if (net_ratelimit())
913 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
914 #endif
915 }
916
917 /*
918 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
919 * loudly if an inconsistency is found.
920 */
921
922 static void icmp_address_reply(struct sk_buff *skb)
923 {
924 struct rtable *rt = skb->rtable;
925 struct net_device *dev = skb->dev;
926 struct in_device *in_dev;
927 struct in_ifaddr *ifa;
928
929 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
930 goto out;
931
932 in_dev = in_dev_get(dev);
933 if (!in_dev)
934 goto out;
935 rcu_read_lock();
936 if (in_dev->ifa_list &&
937 IN_DEV_LOG_MARTIANS(in_dev) &&
938 IN_DEV_FORWARD(in_dev)) {
939 __be32 _mask, *mp;
940
941 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
942 BUG_ON(mp == NULL);
943 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
944 if (*mp == ifa->ifa_mask &&
945 inet_ifa_match(rt->rt_src, ifa))
946 break;
947 }
948 if (!ifa && net_ratelimit()) {
949 printk(KERN_INFO "Wrong address mask " NIPQUAD_FMT " from "
950 "%s/" NIPQUAD_FMT "\n",
951 NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
952 }
953 }
954 rcu_read_unlock();
955 in_dev_put(in_dev);
956 out:;
957 }
958
959 static void icmp_discard(struct sk_buff *skb)
960 {
961 }
962
963 /*
964 * Deal with incoming ICMP packets.
965 */
966 int icmp_rcv(struct sk_buff *skb)
967 {
968 struct icmphdr *icmph;
969 struct rtable *rt = skb->rtable;
970 struct net *net = dev_net(rt->u.dst.dev);
971
972 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
973 int nh;
974
975 if (!(skb->sp && skb->sp->xvec[skb->sp->len - 1]->props.flags &
976 XFRM_STATE_ICMP))
977 goto drop;
978
979 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
980 goto drop;
981
982 nh = skb_network_offset(skb);
983 skb_set_network_header(skb, sizeof(*icmph));
984
985 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
986 goto drop;
987
988 skb_set_network_header(skb, nh);
989 }
990
991 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
992
993 switch (skb->ip_summed) {
994 case CHECKSUM_COMPLETE:
995 if (!csum_fold(skb->csum))
996 break;
997 /* fall through */
998 case CHECKSUM_NONE:
999 skb->csum = 0;
1000 if (__skb_checksum_complete(skb))
1001 goto error;
1002 }
1003
1004 if (!pskb_pull(skb, sizeof(*icmph)))
1005 goto error;
1006
1007 icmph = icmp_hdr(skb);
1008
1009 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1010 /*
1011 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1012 *
1013 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1014 * discarded.
1015 */
1016 if (icmph->type > NR_ICMP_TYPES)
1017 goto error;
1018
1019
1020 /*
1021 * Parse the ICMP message
1022 */
1023
1024 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1025 /*
1026 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1027 * silently ignored (we let user decide with a sysctl).
1028 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1029 * discarded if to broadcast/multicast.
1030 */
1031 if ((icmph->type == ICMP_ECHO ||
1032 icmph->type == ICMP_TIMESTAMP) &&
1033 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1034 goto error;
1035 }
1036 if (icmph->type != ICMP_ECHO &&
1037 icmph->type != ICMP_TIMESTAMP &&
1038 icmph->type != ICMP_ADDRESS &&
1039 icmph->type != ICMP_ADDRESSREPLY) {
1040 goto error;
1041 }
1042 }
1043
1044 icmp_pointers[icmph->type].handler(skb);
1045
1046 drop:
1047 kfree_skb(skb);
1048 return 0;
1049 error:
1050 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1051 goto drop;
1052 }
1053
1054 /*
1055 * This table is the definition of how we handle ICMP.
1056 */
1057 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1058 [ICMP_ECHOREPLY] = {
1059 .handler = icmp_discard,
1060 },
1061 [1] = {
1062 .handler = icmp_discard,
1063 .error = 1,
1064 },
1065 [2] = {
1066 .handler = icmp_discard,
1067 .error = 1,
1068 },
1069 [ICMP_DEST_UNREACH] = {
1070 .handler = icmp_unreach,
1071 .error = 1,
1072 },
1073 [ICMP_SOURCE_QUENCH] = {
1074 .handler = icmp_unreach,
1075 .error = 1,
1076 },
1077 [ICMP_REDIRECT] = {
1078 .handler = icmp_redirect,
1079 .error = 1,
1080 },
1081 [6] = {
1082 .handler = icmp_discard,
1083 .error = 1,
1084 },
1085 [7] = {
1086 .handler = icmp_discard,
1087 .error = 1,
1088 },
1089 [ICMP_ECHO] = {
1090 .handler = icmp_echo,
1091 },
1092 [9] = {
1093 .handler = icmp_discard,
1094 .error = 1,
1095 },
1096 [10] = {
1097 .handler = icmp_discard,
1098 .error = 1,
1099 },
1100 [ICMP_TIME_EXCEEDED] = {
1101 .handler = icmp_unreach,
1102 .error = 1,
1103 },
1104 [ICMP_PARAMETERPROB] = {
1105 .handler = icmp_unreach,
1106 .error = 1,
1107 },
1108 [ICMP_TIMESTAMP] = {
1109 .handler = icmp_timestamp,
1110 },
1111 [ICMP_TIMESTAMPREPLY] = {
1112 .handler = icmp_discard,
1113 },
1114 [ICMP_INFO_REQUEST] = {
1115 .handler = icmp_discard,
1116 },
1117 [ICMP_INFO_REPLY] = {
1118 .handler = icmp_discard,
1119 },
1120 [ICMP_ADDRESS] = {
1121 .handler = icmp_address,
1122 },
1123 [ICMP_ADDRESSREPLY] = {
1124 .handler = icmp_address_reply,
1125 },
1126 };
1127
1128 static void __net_exit icmp_sk_exit(struct net *net)
1129 {
1130 int i;
1131
1132 for_each_possible_cpu(i)
1133 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1134 kfree(net->ipv4.icmp_sk);
1135 net->ipv4.icmp_sk = NULL;
1136 }
1137
1138 static int __net_init icmp_sk_init(struct net *net)
1139 {
1140 int i, err;
1141
1142 net->ipv4.icmp_sk =
1143 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1144 if (net->ipv4.icmp_sk == NULL)
1145 return -ENOMEM;
1146
1147 for_each_possible_cpu(i) {
1148 struct sock *sk;
1149
1150 err = inet_ctl_sock_create(&sk, PF_INET,
1151 SOCK_RAW, IPPROTO_ICMP, net);
1152 if (err < 0)
1153 goto fail;
1154
1155 net->ipv4.icmp_sk[i] = sk;
1156
1157 /* Enough space for 2 64K ICMP packets, including
1158 * sk_buff struct overhead.
1159 */
1160 sk->sk_sndbuf =
1161 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1162
1163 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1164 }
1165
1166 /* Control parameters for ECHO replies. */
1167 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1168 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1169
1170 /* Control parameter - ignore bogus broadcast responses? */
1171 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1172
1173 /*
1174 * Configurable global rate limit.
1175 *
1176 * ratelimit defines tokens/packet consumed for dst->rate_token
1177 * bucket ratemask defines which icmp types are ratelimited by
1178 * setting it's bit position.
1179 *
1180 * default:
1181 * dest unreachable (3), source quench (4),
1182 * time exceeded (11), parameter problem (12)
1183 */
1184
1185 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1186 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1187 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1188
1189 return 0;
1190
1191 fail:
1192 for_each_possible_cpu(i)
1193 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1194 kfree(net->ipv4.icmp_sk);
1195 return err;
1196 }
1197
1198 static struct pernet_operations __net_initdata icmp_sk_ops = {
1199 .init = icmp_sk_init,
1200 .exit = icmp_sk_exit,
1201 };
1202
1203 int __init icmp_init(void)
1204 {
1205 return register_pernet_device(&icmp_sk_ops);
1206 }
1207
1208 EXPORT_SYMBOL(icmp_err_convert);
1209 EXPORT_SYMBOL(icmp_send);
1210 EXPORT_SYMBOL(xrlim_allow);
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