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code style scripts/checkpatch.pl (linux-3.9-rc1) formatting
[linux-2.6.34.14-moxart.git] / net / ipv4 / icmp.c
blobac4dec1327354020b35f7404f5f47f4d463aba3f
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
185 /*
186 * ICMP control array. This specifies what to do with each ICMP.
187 */
188
189 struct icmp_control {
190 void (*handler)(struct sk_buff *skb);
191 short error; /* This ICMP is classed as an error message */
192 };
193
194 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
195
196 /*
197 * The ICMP socket(s). This is the most convenient way to flow control
198 * our ICMP output as well as maintain a clean interface throughout
199 * all layers. All Socketless IP sends will soon be gone.
200 *
201 * On SMP we have one ICMP socket per-cpu.
202 */
203 static struct sock *icmp_sk(struct net *net)
204 {
205 return net->ipv4.icmp_sk[smp_processor_id()];
206 }
207
208 static inline struct sock *icmp_xmit_lock(struct net *net)
209 {
210 struct sock *sk;
211
212 local_bh_disable();
213
214 sk = icmp_sk(net);
215
216 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
217 /* This can happen if the output path signals a
218 * dst_link_failure() for an outgoing ICMP packet.
219 */
220 local_bh_enable();
221 return NULL;
222 }
223 return sk;
224 }
225
226 static inline void icmp_xmit_unlock(struct sock *sk)
227 {
228 spin_unlock_bh(&sk->sk_lock.slock);
229 }
230
231 /*
232 * Send an ICMP frame.
233 */
234
235 /*
236 * Check transmit rate limitation for given message.
237 * The rate information is held in the destination cache now.
238 * This function is generic and could be used for other purposes
239 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
240 *
241 * Note that the same dst_entry fields are modified by functions in
242 * route.c too, but these work for packet destinations while xrlim_allow
243 * works for icmp destinations. This means the rate limiting information
244 * for one "ip object" is shared - and these ICMPs are twice limited:
245 * by source and by destination.
246 *
247 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
248 * SHOULD allow setting of rate limits
249 *
250 * Shared between ICMPv4 and ICMPv6.
251 */
252 #define XRLIM_BURST_FACTOR 6
253 int xrlim_allow(struct dst_entry *dst, int timeout)
254 {
255 unsigned long now, token = dst->rate_tokens;
256 int rc = 0;
257
258 now = jiffies;
259 token += now - dst->rate_last;
260 dst->rate_last = now;
261 if (token > XRLIM_BURST_FACTOR * timeout)
262 token = XRLIM_BURST_FACTOR * timeout;
263 if (token >= timeout) {
264 token -= timeout;
265 rc = 1;
266 }
267 dst->rate_tokens = token;
268 return rc;
269 }
270
271 static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
272 int type, int code)
273 {
274 struct dst_entry *dst = &rt->u.dst;
275 int rc = 1;
276
277 if (type > NR_ICMP_TYPES)
278 goto out;
279
280 /* Don't limit PMTU discovery. */
281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
282 goto out;
283
284 /* No rate limit on loopback */
285 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
286 goto out;
287
288 /* Limit if icmp type is enabled in ratemask. */
289 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask)
290 rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit);
291 out:
292 return rc;
293 }
294
295 /*
296 * Maintain the counters used in the SNMP statistics for outgoing ICMP
297 */
298 void icmp_out_count(struct net *net, unsigned char type)
299 {
300 ICMPMSGOUT_INC_STATS(net, type);
301 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
302 }
303
304 /*
305 * Checksum each fragment, and on the first include the headers and final
306 * checksum.
307 */
308 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
309 struct sk_buff *skb)
310 {
311 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
312 __wsum csum;
313
314 csum = skb_copy_and_csum_bits(icmp_param->skb,
315 icmp_param->offset + offset,
316 to, len, 0);
317
318 skb->csum = csum_block_add(skb->csum, csum, odd);
319 if (icmp_pointers[icmp_param->data.icmph.type].error)
320 nf_ct_attach(skb, icmp_param->skb);
321 return 0;
322 }
323
324 static void icmp_push_reply(struct icmp_bxm *icmp_param,
325 struct ipcm_cookie *ipc, struct rtable **rt)
326 {
327 struct sock *sk;
328 struct sk_buff *skb;
329
330 sk = icmp_sk(dev_net((*rt)->u.dst.dev));
331 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
332 icmp_param->data_len+icmp_param->head_len,
333 icmp_param->head_len,
334 ipc, rt, MSG_DONTWAIT) < 0)
335 ip_flush_pending_frames(sk);
336 else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
337 struct icmphdr *icmph = icmp_hdr(skb);
338 __wsum csum = 0;
339 struct sk_buff *skb1;
340
341 skb_queue_walk(&sk->sk_write_queue, skb1) {
342 csum = csum_add(csum, skb1->csum);
343 }
344 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
345 (char *)icmph,
346 icmp_param->head_len, csum);
347 icmph->checksum = csum_fold(csum);
348 skb->ip_summed = CHECKSUM_NONE;
349 ip_push_pending_frames(sk);
350 }
351 }
352
353 /*
354 * Driving logic for building and sending ICMP messages.
355 */
356
357 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
358 {
359 struct ipcm_cookie ipc;
360 struct rtable *rt = skb_rtable(skb);
361 struct net *net = dev_net(rt->u.dst.dev);
362 struct sock *sk;
363 struct inet_sock *inet;
364 __be32 daddr;
365
366 if (ip_options_echo(&icmp_param->replyopts, skb))
367 return;
368
369 sk = icmp_xmit_lock(net);
370 if (sk == NULL)
371 return;
372 inet = inet_sk(sk);
373
374 icmp_param->data.icmph.checksum = 0;
375
376 inet->tos = ip_hdr(skb)->tos;
377 daddr = ipc.addr = rt->rt_src;
378 ipc.opt = NULL;
379 ipc.shtx.flags = 0;
380 if (icmp_param->replyopts.optlen) {
381 ipc.opt = &icmp_param->replyopts;
382 if (ipc.opt->srr)
383 daddr = icmp_param->replyopts.faddr;
384 }
385 {
386 struct flowi fl = { .nl_u = { .ip4_u =
387 { .daddr = daddr,
388 .saddr = rt->rt_spec_dst,
389 .tos = RT_TOS(ip_hdr(skb)->tos) } },
390 .proto = IPPROTO_ICMP };
391 security_skb_classify_flow(skb, &fl);
392 if (ip_route_output_key(net, &rt, &fl))
393 goto out_unlock;
394 }
395 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
396 icmp_param->data.icmph.code))
397 icmp_push_reply(icmp_param, &ipc, &rt);
398 ip_rt_put(rt);
399 out_unlock:
400 icmp_xmit_unlock(sk);
401 }
402
403
404 /*
405 * Send an ICMP message in response to a situation
406 *
407 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
408 * MAY send more (we do).
409 * MUST NOT change this header information.
410 * MUST NOT reply to a multicast/broadcast IP address.
411 * MUST NOT reply to a multicast/broadcast MAC address.
412 * MUST reply to only the first fragment.
413 */
414
415 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
416 {
417 struct iphdr *iph;
418 int room;
419 struct icmp_bxm icmp_param;
420 struct rtable *rt = skb_rtable(skb_in);
421 struct ipcm_cookie ipc;
422 __be32 saddr;
423 u8 tos;
424 struct net *net;
425 struct sock *sk;
426
427 if (!rt)
428 goto out;
429 net = dev_net(rt->u.dst.dev);
430
431 /*
432 * Find the original header. It is expected to be valid, of course.
433 * Check this, icmp_send is called from the most obscure devices
434 * sometimes.
435 */
436 iph = ip_hdr(skb_in);
437
438 if ((u8 *)iph < skb_in->head ||
439 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
440 goto out;
441
442 /*
443 * No replies to physical multicast/broadcast
444 */
445 if (skb_in->pkt_type != PACKET_HOST)
446 goto out;
447
448 /*
449 * Now check at the protocol level
450 */
451 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
452 goto out;
453
454 /*
455 * Only reply to fragment 0. We byte re-order the constant
456 * mask for efficiency.
457 */
458 if (iph->frag_off & htons(IP_OFFSET))
459 goto out;
460
461 /*
462 * If we send an ICMP error to an ICMP error a mess would result..
463 */
464 if (icmp_pointers[type].error) {
465 /*
466 * We are an error, check if we are replying to an
467 * ICMP error
468 */
469 if (iph->protocol == IPPROTO_ICMP) {
470 u8 _inner_type, *itp;
471
472 itp = skb_header_pointer(skb_in,
473 skb_network_header(skb_in) +
474 (iph->ihl << 2) +
475 offsetof(struct icmphdr,
476 type) -
477 skb_in->data,
478 sizeof(_inner_type),
479 &_inner_type);
480 if (itp == NULL)
481 goto out;
482
483 /*
484 * Assume any unknown ICMP type is an error. This
485 * isn't specified by the RFC, but think about it..
486 */
487 if (*itp > NR_ICMP_TYPES ||
488 icmp_pointers[*itp].error)
489 goto out;
490 }
491 }
492
493 sk = icmp_xmit_lock(net);
494 if (sk == NULL)
495 return;
496
497 /*
498 * Construct source address and options.
499 */
500
501 saddr = iph->daddr;
502 if (!(rt->rt_flags & RTCF_LOCAL)) {
503 struct net_device *dev = NULL;
504
505 rcu_read_lock();
506 if (rt->fl.iif &&
507 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
508 dev = dev_get_by_index_rcu(net, rt->fl.iif);
509
510 if (dev)
511 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
512 else
513 saddr = 0;
514 rcu_read_unlock();
515 }
516
517 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
518 IPTOS_PREC_INTERNETCONTROL) :
519 iph->tos;
520
521 if (ip_options_echo(&icmp_param.replyopts, skb_in))
522 goto out_unlock;
523
524
525 /*
526 * Prepare data for ICMP header.
527 */
528
529 icmp_param.data.icmph.type = type;
530 icmp_param.data.icmph.code = code;
531 icmp_param.data.icmph.un.gateway = info;
532 icmp_param.data.icmph.checksum = 0;
533 icmp_param.skb = skb_in;
534 icmp_param.offset = skb_network_offset(skb_in);
535 inet_sk(sk)->tos = tos;
536 ipc.addr = iph->saddr;
537 ipc.opt = &icmp_param.replyopts;
538 ipc.shtx.flags = 0;
539
540 {
541 struct flowi fl = {
542 .nl_u = {
543 .ip4_u = {
544 .daddr = icmp_param.replyopts.srr ?
545 icmp_param.replyopts.faddr :
546 iph->saddr,
547 .saddr = saddr,
548 .tos = RT_TOS(tos)
549 }
550 },
551 .proto = IPPROTO_ICMP,
552 .uli_u = {
553 .icmpt = {
554 .type = type,
555 .code = code
556 }
557 }
558 };
559 int err;
560 struct rtable *rt2;
561
562 security_skb_classify_flow(skb_in, &fl);
563 if (__ip_route_output_key(net, &rt, &fl))
564 goto out_unlock;
565
566 /* No need to clone since we're just using its address. */
567 rt2 = rt;
568
569 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
570 switch (err) {
571 case 0:
572 if (rt != rt2)
573 goto route_done;
574 break;
575 case -EPERM:
576 rt = NULL;
577 break;
578 default:
579 goto out_unlock;
580 }
581
582 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
583 goto relookup_failed;
584
585 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
586 err = __ip_route_output_key(net, &rt2, &fl);
587 else {
588 struct flowi fl2 = {};
589 struct dst_entry *odst;
590
591 fl2.fl4_dst = fl.fl4_src;
592 if (ip_route_output_key(net, &rt2, &fl2))
593 goto relookup_failed;
594
595 /* Ugh! */
596 odst = skb_dst(skb_in);
597 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
598 RT_TOS(tos), rt2->u.dst.dev);
599
600 dst_release(&rt2->u.dst);
601 rt2 = skb_rtable(skb_in);
602 skb_dst_set(skb_in, odst);
603 }
604
605 if (err)
606 goto relookup_failed;
607
608 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
609 XFRM_LOOKUP_ICMP);
610 switch (err) {
611 case 0:
612 dst_release(&rt->u.dst);
613 rt = rt2;
614 break;
615 case -EPERM:
616 goto ende;
617 default:
618 relookup_failed:
619 if (!rt)
620 goto out_unlock;
621 break;
622 }
623 }
624
625 route_done:
626 if (!icmpv4_xrlim_allow(net, rt, type, code))
627 goto ende;
628
629 /* RFC says return as much as we can without exceeding 576 bytes. */
630
631 room = dst_mtu(&rt->u.dst);
632 if (room > 576)
633 room = 576;
634 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
635 room -= sizeof(struct icmphdr);
636
637 icmp_param.data_len = skb_in->len - icmp_param.offset;
638 if (icmp_param.data_len > room)
639 icmp_param.data_len = room;
640 icmp_param.head_len = sizeof(struct icmphdr);
641
642 icmp_push_reply(&icmp_param, &ipc, &rt);
643 ende:
644 ip_rt_put(rt);
645 out_unlock:
646 icmp_xmit_unlock(sk);
647 out:;
648 }
649
650
651 /*
652 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
653 */
654
655 static void icmp_unreach(struct sk_buff *skb)
656 {
657 struct iphdr *iph;
658 struct icmphdr *icmph;
659 int hash, protocol;
660 const struct net_protocol *ipprot;
661 u32 info = 0;
662 struct net *net;
663
664 net = dev_net(skb_dst(skb)->dev);
665
666 /*
667 * Incomplete header ?
668 * Only checks for the IP header, there should be an
669 * additional check for longer headers in upper levels.
670 */
671
672 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
673 goto out_err;
674
675 icmph = icmp_hdr(skb);
676 iph = (struct iphdr *)skb->data;
677
678 if (iph->ihl < 5) /* Mangled header, drop. */
679 goto out_err;
680
681 if (icmph->type == ICMP_DEST_UNREACH) {
682 switch (icmph->code & 15) {
683 case ICMP_NET_UNREACH:
684 case ICMP_HOST_UNREACH:
685 case ICMP_PROT_UNREACH:
686 case ICMP_PORT_UNREACH:
687 break;
688 case ICMP_FRAG_NEEDED:
689 if (ipv4_config.no_pmtu_disc) {
690 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
691 &iph->daddr);
692 } else {
693 info = ip_rt_frag_needed(net, iph,
694 ntohs(icmph->un.frag.mtu),
695 skb->dev);
696 if (!info)
697 goto out;
698 }
699 break;
700 case ICMP_SR_FAILED:
701 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
702 &iph->daddr);
703 break;
704 default:
705 break;
706 }
707 if (icmph->code > NR_ICMP_UNREACH)
708 goto out;
709 } else if (icmph->type == ICMP_PARAMETERPROB)
710 info = ntohl(icmph->un.gateway) >> 24;
711
712 /*
713 * Throw it at our lower layers
714 *
715 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
716 * header.
717 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
718 * transport layer.
719 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
720 * transport layer.
721 */
722
723 /*
724 * Check the other end isnt violating RFC 1122. Some routers send
725 * bogus responses to broadcast frames. If you see this message
726 * first check your netmask matches at both ends, if it does then
727 * get the other vendor to fix their kit.
728 */
729
730 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
731 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
732 if (net_ratelimit())
733 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
734 "type %u, code %u "
735 "error to a broadcast: %pI4 on %s\n",
736 &ip_hdr(skb)->saddr,
737 icmph->type, icmph->code,
738 &iph->daddr,
739 skb->dev->name);
740 goto out;
741 }
742
743 /* Checkin full IP header plus 8 bytes of protocol to
744 * avoid additional coding at protocol handlers.
745 */
746 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
747 goto out;
748
749 iph = (struct iphdr *)skb->data;
750 protocol = iph->protocol;
751
752 /*
753 * Deliver ICMP message to raw sockets. Pretty useless feature?
754 */
755 raw_icmp_error(skb, protocol, info);
756
757 hash = protocol & (MAX_INET_PROTOS - 1);
758 rcu_read_lock();
759 ipprot = rcu_dereference(inet_protos[hash]);
760 if (ipprot && ipprot->err_handler)
761 ipprot->err_handler(skb, info);
762 rcu_read_unlock();
763
764 out:
765 return;
766 out_err:
767 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
768 goto out;
769 }
770
771
772 /*
773 * Handle ICMP_REDIRECT.
774 */
775
776 static void icmp_redirect(struct sk_buff *skb)
777 {
778 struct iphdr *iph;
779
780 if (skb->len < sizeof(struct iphdr))
781 goto out_err;
782
783 /*
784 * Get the copied header of the packet that caused the redirect
785 */
786 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
787 goto out;
788
789 iph = (struct iphdr *)skb->data;
790
791 switch (icmp_hdr(skb)->code & 7) {
792 case ICMP_REDIR_NET:
793 case ICMP_REDIR_NETTOS:
794 /*
795 * As per RFC recommendations now handle it as a host redirect.
796 */
797 case ICMP_REDIR_HOST:
798 case ICMP_REDIR_HOSTTOS:
799 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
800 icmp_hdr(skb)->un.gateway,
801 iph->saddr, skb->dev);
802 break;
803 }
804 out:
805 return;
806 out_err:
807 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
808 goto out;
809 }
810
811 /*
812 * Handle ICMP_ECHO ("ping") requests.
813 *
814 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
815 * requests.
816 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
817 * included in the reply.
818 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
819 * echo requests, MUST have default=NOT.
820 * See also WRT handling of options once they are done and working.
821 */
822
823 static void icmp_echo(struct sk_buff *skb)
824 {
825 struct net *net;
826
827 net = dev_net(skb_dst(skb)->dev);
828 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
829 struct icmp_bxm icmp_param;
830
831 icmp_param.data.icmph = *icmp_hdr(skb);
832 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
833 icmp_param.skb = skb;
834 icmp_param.offset = 0;
835 icmp_param.data_len = skb->len;
836 icmp_param.head_len = sizeof(struct icmphdr);
837 icmp_reply(&icmp_param, skb);
838 }
839 }
840
841 /*
842 * Handle ICMP Timestamp requests.
843 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
844 * SHOULD be in the kernel for minimum random latency.
845 * MUST be accurate to a few minutes.
846 * MUST be updated at least at 15Hz.
847 */
848 static void icmp_timestamp(struct sk_buff *skb)
849 {
850 struct timespec tv;
851 struct icmp_bxm icmp_param;
852 /*
853 * Too short.
854 */
855 if (skb->len < 4)
856 goto out_err;
857
858 /*
859 * Fill in the current time as ms since midnight UT:
860 */
861 getnstimeofday(&tv);
862 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
863 tv.tv_nsec / NSEC_PER_MSEC);
864 icmp_param.data.times[2] = icmp_param.data.times[1];
865 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
866 BUG();
867 icmp_param.data.icmph = *icmp_hdr(skb);
868 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
869 icmp_param.data.icmph.code = 0;
870 icmp_param.skb = skb;
871 icmp_param.offset = 0;
872 icmp_param.data_len = 0;
873 icmp_param.head_len = sizeof(struct icmphdr) + 12;
874 icmp_reply(&icmp_param, skb);
875 out:
876 return;
877 out_err:
878 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
879 goto out;
880 }
881
882
883 /*
884 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
885 *
886 * RFC1122 (3.2.2.9). A host MUST only send replies to
887 * ADDRESS_MASK requests if it's been configured as an address mask
888 * agent. Receiving a request doesn't constitute implicit permission to
889 * act as one. Of course, implementing this correctly requires (SHOULD)
890 * a way to turn the functionality on and off. Another one for sysctl(),
891 * I guess. -- MS
892 *
893 * RFC1812 (4.3.3.9). A router MUST implement it.
894 * A router SHOULD have switch turning it on/off.
895 * This switch MUST be ON by default.
896 *
897 * Gratuitous replies, zero-source replies are not implemented,
898 * that complies with RFC. DO NOT implement them!!! All the idea
899 * of broadcast addrmask replies as specified in RFC950 is broken.
900 * The problem is that it is not uncommon to have several prefixes
901 * on one physical interface. Moreover, addrmask agent can even be
902 * not aware of existing another prefixes.
903 * If source is zero, addrmask agent cannot choose correct prefix.
904 * Gratuitous mask announcements suffer from the same problem.
905 * RFC1812 explains it, but still allows to use ADDRMASK,
906 * that is pretty silly. --ANK
907 *
908 * All these rules are so bizarre, that I removed kernel addrmask
909 * support at all. It is wrong, it is obsolete, nobody uses it in
910 * any case. --ANK
911 *
912 * Furthermore you can do it with a usermode address agent program
913 * anyway...
914 */
915
916 static void icmp_address(struct sk_buff *skb)
917 {
918 #if 0
919 if (net_ratelimit())
920 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
921 #endif
922 }
923
924 /*
925 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
926 * loudly if an inconsistency is found.
927 */
928
929 static void icmp_address_reply(struct sk_buff *skb)
930 {
931 struct rtable *rt = skb_rtable(skb);
932 struct net_device *dev = skb->dev;
933 struct in_device *in_dev;
934 struct in_ifaddr *ifa;
935
936 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
937 goto out;
938
939 in_dev = in_dev_get(dev);
940 if (!in_dev)
941 goto out;
942 rcu_read_lock();
943 if (in_dev->ifa_list &&
944 IN_DEV_LOG_MARTIANS(in_dev) &&
945 IN_DEV_FORWARD(in_dev)) {
946 __be32 _mask, *mp;
947
948 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
949 BUG_ON(mp == NULL);
950 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
951 if (*mp == ifa->ifa_mask &&
952 inet_ifa_match(rt->rt_src, ifa))
953 break;
954 }
955 if (!ifa && net_ratelimit()) {
956 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
957 mp, dev->name, &rt->rt_src);
958 }
959 }
960 rcu_read_unlock();
961 in_dev_put(in_dev);
962 out:;
963 }
964
965 static void icmp_discard(struct sk_buff *skb)
966 {
967 }
968
969 /*
970 * Deal with incoming ICMP packets.
971 */
972 int icmp_rcv(struct sk_buff *skb)
973 {
974 struct icmphdr *icmph;
975 struct rtable *rt = skb_rtable(skb);
976 struct net *net = dev_net(rt->u.dst.dev);
977
978 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
979 struct sec_path *sp = skb_sec_path(skb);
980 int nh;
981
982 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
983 XFRM_STATE_ICMP))
984 goto drop;
985
986 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
987 goto drop;
988
989 nh = skb_network_offset(skb);
990 skb_set_network_header(skb, sizeof(*icmph));
991
992 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
993 goto drop;
994
995 skb_set_network_header(skb, nh);
996 }
997
998 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
999
1000 switch (skb->ip_summed) {
1001 case CHECKSUM_COMPLETE:
1002 if (!csum_fold(skb->csum))
1003 break;
1004 /* fall through */
1005 case CHECKSUM_NONE:
1006 skb->csum = 0;
1007 if (__skb_checksum_complete(skb))
1008 goto error;
1009 }
1010
1011 if (!pskb_pull(skb, sizeof(*icmph)))
1012 goto error;
1013
1014 icmph = icmp_hdr(skb);
1015
1016 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1017 /*
1018 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1019 *
1020 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1021 * discarded.
1022 */
1023 if (icmph->type > NR_ICMP_TYPES)
1024 goto error;
1025
1026
1027 /*
1028 * Parse the ICMP message
1029 */
1030
1031 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1032 /*
1033 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1034 * silently ignored (we let user decide with a sysctl).
1035 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1036 * discarded if to broadcast/multicast.
1037 */
1038 if ((icmph->type == ICMP_ECHO ||
1039 icmph->type == ICMP_TIMESTAMP) &&
1040 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1041 goto error;
1042 }
1043 if (icmph->type != ICMP_ECHO &&
1044 icmph->type != ICMP_TIMESTAMP &&
1045 icmph->type != ICMP_ADDRESS &&
1046 icmph->type != ICMP_ADDRESSREPLY) {
1047 goto error;
1048 }
1049 }
1050
1051 icmp_pointers[icmph->type].handler(skb);
1052
1053 drop:
1054 kfree_skb(skb);
1055 return 0;
1056 error:
1057 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1058 goto drop;
1059 }
1060
1061 /*
1062 * This table is the definition of how we handle ICMP.
1063 */
1064 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1065 [ICMP_ECHOREPLY] = {
1066 .handler = icmp_discard,
1067 },
1068 [1] = {
1069 .handler = icmp_discard,
1070 .error = 1,
1071 },
1072 [2] = {
1073 .handler = icmp_discard,
1074 .error = 1,
1075 },
1076 [ICMP_DEST_UNREACH] = {
1077 .handler = icmp_unreach,
1078 .error = 1,
1079 },
1080 [ICMP_SOURCE_QUENCH] = {
1081 .handler = icmp_unreach,
1082 .error = 1,
1083 },
1084 [ICMP_REDIRECT] = {
1085 .handler = icmp_redirect,
1086 .error = 1,
1087 },
1088 [6] = {
1089 .handler = icmp_discard,
1090 .error = 1,
1091 },
1092 [7] = {
1093 .handler = icmp_discard,
1094 .error = 1,
1095 },
1096 [ICMP_ECHO] = {
1097 .handler = icmp_echo,
1098 },
1099 [9] = {
1100 .handler = icmp_discard,
1101 .error = 1,
1102 },
1103 [10] = {
1104 .handler = icmp_discard,
1105 .error = 1,
1106 },
1107 [ICMP_TIME_EXCEEDED] = {
1108 .handler = icmp_unreach,
1109 .error = 1,
1110 },
1111 [ICMP_PARAMETERPROB] = {
1112 .handler = icmp_unreach,
1113 .error = 1,
1114 },
1115 [ICMP_TIMESTAMP] = {
1116 .handler = icmp_timestamp,
1117 },
1118 [ICMP_TIMESTAMPREPLY] = {
1119 .handler = icmp_discard,
1120 },
1121 [ICMP_INFO_REQUEST] = {
1122 .handler = icmp_discard,
1123 },
1124 [ICMP_INFO_REPLY] = {
1125 .handler = icmp_discard,
1126 },
1127 [ICMP_ADDRESS] = {
1128 .handler = icmp_address,
1129 },
1130 [ICMP_ADDRESSREPLY] = {
1131 .handler = icmp_address_reply,
1132 },
1133 };
1134
1135 static void __net_exit icmp_sk_exit(struct net *net)
1136 {
1137 int i;
1138
1139 for_each_possible_cpu(i)
1140 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1141 kfree(net->ipv4.icmp_sk);
1142 net->ipv4.icmp_sk = NULL;
1143 }
1144
1145 static int __net_init icmp_sk_init(struct net *net)
1146 {
1147 int i, err;
1148
1149 net->ipv4.icmp_sk =
1150 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1151 if (net->ipv4.icmp_sk == NULL)
1152 return -ENOMEM;
1153
1154 for_each_possible_cpu(i) {
1155 struct sock *sk;
1156
1157 err = inet_ctl_sock_create(&sk, PF_INET,
1158 SOCK_RAW, IPPROTO_ICMP, net);
1159 if (err < 0)
1160 goto fail;
1161
1162 net->ipv4.icmp_sk[i] = sk;
1163
1164 /* Enough space for 2 64K ICMP packets, including
1165 * sk_buff struct overhead.
1166 */
1167 sk->sk_sndbuf =
1168 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1169
1170 /*
1171 * Speedup sock_wfree()
1172 */
1173 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1174 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1175 }
1176
1177 /* Control parameters for ECHO replies. */
1178 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1179 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1180
1181 /* Control parameter - ignore bogus broadcast responses? */
1182 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1183
1184 /*
1185 * Configurable global rate limit.
1186 *
1187 * ratelimit defines tokens/packet consumed for dst->rate_token
1188 * bucket ratemask defines which icmp types are ratelimited by
1189 * setting it's bit position.
1190 *
1191 * default:
1192 * dest unreachable (3), source quench (4),
1193 * time exceeded (11), parameter problem (12)
1194 */
1195
1196 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1197 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1198 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1199
1200 return 0;
1201
1202 fail:
1203 for_each_possible_cpu(i)
1204 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1205 kfree(net->ipv4.icmp_sk);
1206 return err;
1207 }
1208
1209 static struct pernet_operations __net_initdata icmp_sk_ops = {
1210 .init = icmp_sk_init,
1211 .exit = icmp_sk_exit,
1212 };
1213
1214 int __init icmp_init(void)
1215 {
1216 return register_pernet_subsys(&icmp_sk_ops);
1217 }
1218
1219 EXPORT_SYMBOL(icmp_err_convert);
1220 EXPORT_SYMBOL(icmp_send);
1221 EXPORT_SYMBOL(xrlim_allow);
Linux ARM platform port for MOXA ART SoC