?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
ext4: use kmem_cache_zalloc() in ext4_init_io_end()
[zen-stable.git] / net / ipv4 / icmp.c
blobe5d1a44bcbdf04b851d441ea5ebd8fbe44514704
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 = { .nl_u = { .ip4_u =
390 { .daddr = daddr,
391 .saddr = rt->rt_spec_dst,
392 .tos = RT_TOS(ip_hdr(skb)->tos) } },
393 .proto = IPPROTO_ICMP };
394 security_skb_classify_flow(skb, &fl);
395 if (ip_route_output_key(net, &rt, &fl))
396 goto out_unlock;
397 }
398 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
399 icmp_param->data.icmph.code))
400 icmp_push_reply(icmp_param, &ipc, &rt);
401 ip_rt_put(rt);
402 out_unlock:
403 icmp_xmit_unlock(sk);
404 }
405
406
407 /*
408 * Send an ICMP message in response to a situation
409 *
410 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
411 * MAY send more (we do).
412 * MUST NOT change this header information.
413 * MUST NOT reply to a multicast/broadcast IP address.
414 * MUST NOT reply to a multicast/broadcast MAC address.
415 * MUST reply to only the first fragment.
416 */
417
418 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
419 {
420 struct iphdr *iph;
421 int room;
422 struct icmp_bxm icmp_param;
423 struct rtable *rt = skb_rtable(skb_in);
424 struct ipcm_cookie ipc;
425 __be32 saddr;
426 u8 tos;
427 struct net *net;
428 struct sock *sk;
429
430 if (!rt)
431 goto out;
432 net = dev_net(rt->dst.dev);
433
434 /*
435 * Find the original header. It is expected to be valid, of course.
436 * Check this, icmp_send is called from the most obscure devices
437 * sometimes.
438 */
439 iph = ip_hdr(skb_in);
440
441 if ((u8 *)iph < skb_in->head ||
442 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
443 goto out;
444
445 /*
446 * No replies to physical multicast/broadcast
447 */
448 if (skb_in->pkt_type != PACKET_HOST)
449 goto out;
450
451 /*
452 * Now check at the protocol level
453 */
454 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
455 goto out;
456
457 /*
458 * Only reply to fragment 0. We byte re-order the constant
459 * mask for efficiency.
460 */
461 if (iph->frag_off & htons(IP_OFFSET))
462 goto out;
463
464 /*
465 * If we send an ICMP error to an ICMP error a mess would result..
466 */
467 if (icmp_pointers[type].error) {
468 /*
469 * We are an error, check if we are replying to an
470 * ICMP error
471 */
472 if (iph->protocol == IPPROTO_ICMP) {
473 u8 _inner_type, *itp;
474
475 itp = skb_header_pointer(skb_in,
476 skb_network_header(skb_in) +
477 (iph->ihl << 2) +
478 offsetof(struct icmphdr,
479 type) -
480 skb_in->data,
481 sizeof(_inner_type),
482 &_inner_type);
483 if (itp == NULL)
484 goto out;
485
486 /*
487 * Assume any unknown ICMP type is an error. This
488 * isn't specified by the RFC, but think about it..
489 */
490 if (*itp > NR_ICMP_TYPES ||
491 icmp_pointers[*itp].error)
492 goto out;
493 }
494 }
495
496 sk = icmp_xmit_lock(net);
497 if (sk == NULL)
498 return;
499
500 /*
501 * Construct source address and options.
502 */
503
504 saddr = iph->daddr;
505 if (!(rt->rt_flags & RTCF_LOCAL)) {
506 struct net_device *dev = NULL;
507
508 rcu_read_lock();
509 if (rt->fl.iif &&
510 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
511 dev = dev_get_by_index_rcu(net, rt->fl.iif);
512
513 if (dev)
514 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
515 else
516 saddr = 0;
517 rcu_read_unlock();
518 }
519
520 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
521 IPTOS_PREC_INTERNETCONTROL) :
522 iph->tos;
523
524 if (ip_options_echo(&icmp_param.replyopts, skb_in))
525 goto out_unlock;
526
527
528 /*
529 * Prepare data for ICMP header.
530 */
531
532 icmp_param.data.icmph.type = type;
533 icmp_param.data.icmph.code = code;
534 icmp_param.data.icmph.un.gateway = info;
535 icmp_param.data.icmph.checksum = 0;
536 icmp_param.skb = skb_in;
537 icmp_param.offset = skb_network_offset(skb_in);
538 inet_sk(sk)->tos = tos;
539 ipc.addr = iph->saddr;
540 ipc.opt = &icmp_param.replyopts;
541 ipc.tx_flags = 0;
542
543 {
544 struct flowi fl = {
545 .nl_u = {
546 .ip4_u = {
547 .daddr = icmp_param.replyopts.srr ?
548 icmp_param.replyopts.faddr :
549 iph->saddr,
550 .saddr = saddr,
551 .tos = RT_TOS(tos)
552 }
553 },
554 .proto = IPPROTO_ICMP,
555 .uli_u = {
556 .icmpt = {
557 .type = type,
558 .code = code
559 }
560 }
561 };
562 int err;
563 struct rtable *rt2;
564
565 security_skb_classify_flow(skb_in, &fl);
566 if (__ip_route_output_key(net, &rt, &fl))
567 goto out_unlock;
568
569 /* No need to clone since we're just using its address. */
570 rt2 = rt;
571
572 if (!fl.nl_u.ip4_u.saddr)
573 fl.nl_u.ip4_u.saddr = rt->rt_src;
574
575 err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0);
576 switch (err) {
577 case 0:
578 if (rt != rt2)
579 goto route_done;
580 break;
581 case -EPERM:
582 rt = NULL;
583 break;
584 default:
585 goto out_unlock;
586 }
587
588 if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
589 goto relookup_failed;
590
591 if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
592 err = __ip_route_output_key(net, &rt2, &fl);
593 else {
594 struct flowi fl2 = {};
595 unsigned long orefdst;
596
597 fl2.fl4_dst = fl.fl4_src;
598 if (ip_route_output_key(net, &rt2, &fl2))
599 goto relookup_failed;
600
601 /* Ugh! */
602 orefdst = skb_in->_skb_refdst; /* save old refdst */
603 err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src,
604 RT_TOS(tos), rt2->dst.dev);
605
606 dst_release(&rt2->dst);
607 rt2 = skb_rtable(skb_in);
608 skb_in->_skb_refdst = orefdst; /* restore old refdst */
609 }
610
611 if (err)
612 goto relookup_failed;
613
614 err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL,
615 XFRM_LOOKUP_ICMP);
616 switch (err) {
617 case 0:
618 dst_release(&rt->dst);
619 rt = rt2;
620 break;
621 case -EPERM:
622 goto ende;
623 default:
624 relookup_failed:
625 if (!rt)
626 goto out_unlock;
627 break;
628 }
629 }
630
631 route_done:
632 if (!icmpv4_xrlim_allow(net, rt, type, code))
633 goto ende;
634
635 /* RFC says return as much as we can without exceeding 576 bytes. */
636
637 room = dst_mtu(&rt->dst);
638 if (room > 576)
639 room = 576;
640 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
641 room -= sizeof(struct icmphdr);
642
643 icmp_param.data_len = skb_in->len - icmp_param.offset;
644 if (icmp_param.data_len > room)
645 icmp_param.data_len = room;
646 icmp_param.head_len = sizeof(struct icmphdr);
647
648 icmp_push_reply(&icmp_param, &ipc, &rt);
649 ende:
650 ip_rt_put(rt);
651 out_unlock:
652 icmp_xmit_unlock(sk);
653 out:;
654 }
655 EXPORT_SYMBOL(icmp_send);
656
657
658 /*
659 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
660 */
661
662 static void icmp_unreach(struct sk_buff *skb)
663 {
664 struct iphdr *iph;
665 struct icmphdr *icmph;
666 int hash, protocol;
667 const struct net_protocol *ipprot;
668 u32 info = 0;
669 struct net *net;
670
671 net = dev_net(skb_dst(skb)->dev);
672
673 /*
674 * Incomplete header ?
675 * Only checks for the IP header, there should be an
676 * additional check for longer headers in upper levels.
677 */
678
679 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
680 goto out_err;
681
682 icmph = icmp_hdr(skb);
683 iph = (struct iphdr *)skb->data;
684
685 if (iph->ihl < 5) /* Mangled header, drop. */
686 goto out_err;
687
688 if (icmph->type == ICMP_DEST_UNREACH) {
689 switch (icmph->code & 15) {
690 case ICMP_NET_UNREACH:
691 case ICMP_HOST_UNREACH:
692 case ICMP_PROT_UNREACH:
693 case ICMP_PORT_UNREACH:
694 break;
695 case ICMP_FRAG_NEEDED:
696 if (ipv4_config.no_pmtu_disc) {
697 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
698 &iph->daddr);
699 } else {
700 info = ip_rt_frag_needed(net, iph,
701 ntohs(icmph->un.frag.mtu),
702 skb->dev);
703 if (!info)
704 goto out;
705 }
706 break;
707 case ICMP_SR_FAILED:
708 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
709 &iph->daddr);
710 break;
711 default:
712 break;
713 }
714 if (icmph->code > NR_ICMP_UNREACH)
715 goto out;
716 } else if (icmph->type == ICMP_PARAMETERPROB)
717 info = ntohl(icmph->un.gateway) >> 24;
718
719 /*
720 * Throw it at our lower layers
721 *
722 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
723 * header.
724 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
725 * transport layer.
726 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
727 * transport layer.
728 */
729
730 /*
731 * Check the other end isnt violating RFC 1122. Some routers send
732 * bogus responses to broadcast frames. If you see this message
733 * first check your netmask matches at both ends, if it does then
734 * get the other vendor to fix their kit.
735 */
736
737 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
738 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
739 if (net_ratelimit())
740 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
741 "type %u, code %u "
742 "error to a broadcast: %pI4 on %s\n",
743 &ip_hdr(skb)->saddr,
744 icmph->type, icmph->code,
745 &iph->daddr,
746 skb->dev->name);
747 goto out;
748 }
749
750 /* Checkin full IP header plus 8 bytes of protocol to
751 * avoid additional coding at protocol handlers.
752 */
753 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
754 goto out;
755
756 iph = (struct iphdr *)skb->data;
757 protocol = iph->protocol;
758
759 /*
760 * Deliver ICMP message to raw sockets. Pretty useless feature?
761 */
762 raw_icmp_error(skb, protocol, info);
763
764 hash = protocol & (MAX_INET_PROTOS - 1);
765 rcu_read_lock();
766 ipprot = rcu_dereference(inet_protos[hash]);
767 if (ipprot && ipprot->err_handler)
768 ipprot->err_handler(skb, info);
769 rcu_read_unlock();
770
771 out:
772 return;
773 out_err:
774 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
775 goto out;
776 }
777
778
779 /*
780 * Handle ICMP_REDIRECT.
781 */
782
783 static void icmp_redirect(struct sk_buff *skb)
784 {
785 struct iphdr *iph;
786
787 if (skb->len < sizeof(struct iphdr))
788 goto out_err;
789
790 /*
791 * Get the copied header of the packet that caused the redirect
792 */
793 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
794 goto out;
795
796 iph = (struct iphdr *)skb->data;
797
798 switch (icmp_hdr(skb)->code & 7) {
799 case ICMP_REDIR_NET:
800 case ICMP_REDIR_NETTOS:
801 /*
802 * As per RFC recommendations now handle it as a host redirect.
803 */
804 case ICMP_REDIR_HOST:
805 case ICMP_REDIR_HOSTTOS:
806 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
807 icmp_hdr(skb)->un.gateway,
808 iph->saddr, skb->dev);
809 break;
810 }
811 out:
812 return;
813 out_err:
814 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
815 goto out;
816 }
817
818 /*
819 * Handle ICMP_ECHO ("ping") requests.
820 *
821 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
822 * requests.
823 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
824 * included in the reply.
825 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
826 * echo requests, MUST have default=NOT.
827 * See also WRT handling of options once they are done and working.
828 */
829
830 static void icmp_echo(struct sk_buff *skb)
831 {
832 struct net *net;
833
834 net = dev_net(skb_dst(skb)->dev);
835 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
836 struct icmp_bxm icmp_param;
837
838 icmp_param.data.icmph = *icmp_hdr(skb);
839 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
840 icmp_param.skb = skb;
841 icmp_param.offset = 0;
842 icmp_param.data_len = skb->len;
843 icmp_param.head_len = sizeof(struct icmphdr);
844 icmp_reply(&icmp_param, skb);
845 }
846 }
847
848 /*
849 * Handle ICMP Timestamp requests.
850 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
851 * SHOULD be in the kernel for minimum random latency.
852 * MUST be accurate to a few minutes.
853 * MUST be updated at least at 15Hz.
854 */
855 static void icmp_timestamp(struct sk_buff *skb)
856 {
857 struct timespec tv;
858 struct icmp_bxm icmp_param;
859 /*
860 * Too short.
861 */
862 if (skb->len < 4)
863 goto out_err;
864
865 /*
866 * Fill in the current time as ms since midnight UT:
867 */
868 getnstimeofday(&tv);
869 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
870 tv.tv_nsec / NSEC_PER_MSEC);
871 icmp_param.data.times[2] = icmp_param.data.times[1];
872 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
873 BUG();
874 icmp_param.data.icmph = *icmp_hdr(skb);
875 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
876 icmp_param.data.icmph.code = 0;
877 icmp_param.skb = skb;
878 icmp_param.offset = 0;
879 icmp_param.data_len = 0;
880 icmp_param.head_len = sizeof(struct icmphdr) + 12;
881 icmp_reply(&icmp_param, skb);
882 out:
883 return;
884 out_err:
885 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
886 goto out;
887 }
888
889
890 /*
891 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
892 *
893 * RFC1122 (3.2.2.9). A host MUST only send replies to
894 * ADDRESS_MASK requests if it's been configured as an address mask
895 * agent. Receiving a request doesn't constitute implicit permission to
896 * act as one. Of course, implementing this correctly requires (SHOULD)
897 * a way to turn the functionality on and off. Another one for sysctl(),
898 * I guess. -- MS
899 *
900 * RFC1812 (4.3.3.9). A router MUST implement it.
901 * A router SHOULD have switch turning it on/off.
902 * This switch MUST be ON by default.
903 *
904 * Gratuitous replies, zero-source replies are not implemented,
905 * that complies with RFC. DO NOT implement them!!! All the idea
906 * of broadcast addrmask replies as specified in RFC950 is broken.
907 * The problem is that it is not uncommon to have several prefixes
908 * on one physical interface. Moreover, addrmask agent can even be
909 * not aware of existing another prefixes.
910 * If source is zero, addrmask agent cannot choose correct prefix.
911 * Gratuitous mask announcements suffer from the same problem.
912 * RFC1812 explains it, but still allows to use ADDRMASK,
913 * that is pretty silly. --ANK
914 *
915 * All these rules are so bizarre, that I removed kernel addrmask
916 * support at all. It is wrong, it is obsolete, nobody uses it in
917 * any case. --ANK
918 *
919 * Furthermore you can do it with a usermode address agent program
920 * anyway...
921 */
922
923 static void icmp_address(struct sk_buff *skb)
924 {
925 #if 0
926 if (net_ratelimit())
927 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
928 #endif
929 }
930
931 /*
932 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
933 * loudly if an inconsistency is found.
934 * called with rcu_read_lock()
935 */
936
937 static void icmp_address_reply(struct sk_buff *skb)
938 {
939 struct rtable *rt = skb_rtable(skb);
940 struct net_device *dev = skb->dev;
941 struct in_device *in_dev;
942 struct in_ifaddr *ifa;
943
944 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
945 return;
946
947 in_dev = __in_dev_get_rcu(dev);
948 if (!in_dev)
949 return;
950
951 if (in_dev->ifa_list &&
952 IN_DEV_LOG_MARTIANS(in_dev) &&
953 IN_DEV_FORWARD(in_dev)) {
954 __be32 _mask, *mp;
955
956 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
957 BUG_ON(mp == NULL);
958 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
959 if (*mp == ifa->ifa_mask &&
960 inet_ifa_match(rt->rt_src, ifa))
961 break;
962 }
963 if (!ifa && net_ratelimit()) {
964 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
965 mp, dev->name, &rt->rt_src);
966 }
967 }
968 }
969
970 static void icmp_discard(struct sk_buff *skb)
971 {
972 }
973
974 /*
975 * Deal with incoming ICMP packets.
976 */
977 int icmp_rcv(struct sk_buff *skb)
978 {
979 struct icmphdr *icmph;
980 struct rtable *rt = skb_rtable(skb);
981 struct net *net = dev_net(rt->dst.dev);
982
983 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
984 struct sec_path *sp = skb_sec_path(skb);
985 int nh;
986
987 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
988 XFRM_STATE_ICMP))
989 goto drop;
990
991 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
992 goto drop;
993
994 nh = skb_network_offset(skb);
995 skb_set_network_header(skb, sizeof(*icmph));
996
997 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
998 goto drop;
999
1000 skb_set_network_header(skb, nh);
1001 }
1002
1003 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
1004
1005 switch (skb->ip_summed) {
1006 case CHECKSUM_COMPLETE:
1007 if (!csum_fold(skb->csum))
1008 break;
1009 /* fall through */
1010 case CHECKSUM_NONE:
1011 skb->csum = 0;
1012 if (__skb_checksum_complete(skb))
1013 goto error;
1014 }
1015
1016 if (!pskb_pull(skb, sizeof(*icmph)))
1017 goto error;
1018
1019 icmph = icmp_hdr(skb);
1020
1021 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1022 /*
1023 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1024 *
1025 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1026 * discarded.
1027 */
1028 if (icmph->type > NR_ICMP_TYPES)
1029 goto error;
1030
1031
1032 /*
1033 * Parse the ICMP message
1034 */
1035
1036 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1037 /*
1038 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1039 * silently ignored (we let user decide with a sysctl).
1040 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1041 * discarded if to broadcast/multicast.
1042 */
1043 if ((icmph->type == ICMP_ECHO ||
1044 icmph->type == ICMP_TIMESTAMP) &&
1045 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1046 goto error;
1047 }
1048 if (icmph->type != ICMP_ECHO &&
1049 icmph->type != ICMP_TIMESTAMP &&
1050 icmph->type != ICMP_ADDRESS &&
1051 icmph->type != ICMP_ADDRESSREPLY) {
1052 goto error;
1053 }
1054 }
1055
1056 icmp_pointers[icmph->type].handler(skb);
1057
1058 drop:
1059 kfree_skb(skb);
1060 return 0;
1061 error:
1062 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1063 goto drop;
1064 }
1065
1066 /*
1067 * This table is the definition of how we handle ICMP.
1068 */
1069 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1070 [ICMP_ECHOREPLY] = {
1071 .handler = icmp_discard,
1072 },
1073 [1] = {
1074 .handler = icmp_discard,
1075 .error = 1,
1076 },
1077 [2] = {
1078 .handler = icmp_discard,
1079 .error = 1,
1080 },
1081 [ICMP_DEST_UNREACH] = {
1082 .handler = icmp_unreach,
1083 .error = 1,
1084 },
1085 [ICMP_SOURCE_QUENCH] = {
1086 .handler = icmp_unreach,
1087 .error = 1,
1088 },
1089 [ICMP_REDIRECT] = {
1090 .handler = icmp_redirect,
1091 .error = 1,
1092 },
1093 [6] = {
1094 .handler = icmp_discard,
1095 .error = 1,
1096 },
1097 [7] = {
1098 .handler = icmp_discard,
1099 .error = 1,
1100 },
1101 [ICMP_ECHO] = {
1102 .handler = icmp_echo,
1103 },
1104 [9] = {
1105 .handler = icmp_discard,
1106 .error = 1,
1107 },
1108 [10] = {
1109 .handler = icmp_discard,
1110 .error = 1,
1111 },
1112 [ICMP_TIME_EXCEEDED] = {
1113 .handler = icmp_unreach,
1114 .error = 1,
1115 },
1116 [ICMP_PARAMETERPROB] = {
1117 .handler = icmp_unreach,
1118 .error = 1,
1119 },
1120 [ICMP_TIMESTAMP] = {
1121 .handler = icmp_timestamp,
1122 },
1123 [ICMP_TIMESTAMPREPLY] = {
1124 .handler = icmp_discard,
1125 },
1126 [ICMP_INFO_REQUEST] = {
1127 .handler = icmp_discard,
1128 },
1129 [ICMP_INFO_REPLY] = {
1130 .handler = icmp_discard,
1131 },
1132 [ICMP_ADDRESS] = {
1133 .handler = icmp_address,
1134 },
1135 [ICMP_ADDRESSREPLY] = {
1136 .handler = icmp_address_reply,
1137 },
1138 };
1139
1140 static void __net_exit icmp_sk_exit(struct net *net)
1141 {
1142 int i;
1143
1144 for_each_possible_cpu(i)
1145 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1146 kfree(net->ipv4.icmp_sk);
1147 net->ipv4.icmp_sk = NULL;
1148 }
1149
1150 static int __net_init icmp_sk_init(struct net *net)
1151 {
1152 int i, err;
1153
1154 net->ipv4.icmp_sk =
1155 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1156 if (net->ipv4.icmp_sk == NULL)
1157 return -ENOMEM;
1158
1159 for_each_possible_cpu(i) {
1160 struct sock *sk;
1161
1162 err = inet_ctl_sock_create(&sk, PF_INET,
1163 SOCK_RAW, IPPROTO_ICMP, net);
1164 if (err < 0)
1165 goto fail;
1166
1167 net->ipv4.icmp_sk[i] = sk;
1168
1169 /* Enough space for 2 64K ICMP packets, including
1170 * sk_buff struct overhead.
1171 */
1172 sk->sk_sndbuf =
1173 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1174
1175 /*
1176 * Speedup sock_wfree()
1177 */
1178 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1179 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1180 }
1181
1182 /* Control parameters for ECHO replies. */
1183 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1184 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1185
1186 /* Control parameter - ignore bogus broadcast responses? */
1187 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1188
1189 /*
1190 * Configurable global rate limit.
1191 *
1192 * ratelimit defines tokens/packet consumed for dst->rate_token
1193 * bucket ratemask defines which icmp types are ratelimited by
1194 * setting it's bit position.
1195 *
1196 * default:
1197 * dest unreachable (3), source quench (4),
1198 * time exceeded (11), parameter problem (12)
1199 */
1200
1201 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1202 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1203 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1204
1205 return 0;
1206
1207 fail:
1208 for_each_possible_cpu(i)
1209 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1210 kfree(net->ipv4.icmp_sk);
1211 return err;
1212 }
1213
1214 static struct pernet_operations __net_initdata icmp_sk_ops = {
1215 .init = icmp_sk_init,
1216 .exit = icmp_sk_exit,
1217 };
1218
1219 int __init icmp_init(void)
1220 {
1221 return register_pernet_subsys(&icmp_sk_ops);
1222 }