Loading...
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66
67#include <linux/module.h>
68#include <linux/types.h>
69#include <linux/jiffies.h>
70#include <linux/kernel.h>
71#include <linux/fcntl.h>
72#include <linux/socket.h>
73#include <linux/in.h>
74#include <linux/inet.h>
75#include <linux/inetdevice.h>
76#include <linux/netdevice.h>
77#include <linux/string.h>
78#include <linux/netfilter_ipv4.h>
79#include <linux/slab.h>
80#include <net/snmp.h>
81#include <net/ip.h>
82#include <net/route.h>
83#include <net/protocol.h>
84#include <net/icmp.h>
85#include <net/tcp.h>
86#include <net/udp.h>
87#include <net/raw.h>
88#include <net/ping.h>
89#include <linux/skbuff.h>
90#include <net/sock.h>
91#include <linux/errno.h>
92#include <linux/timer.h>
93#include <linux/init.h>
94#include <asm/uaccess.h>
95#include <net/checksum.h>
96#include <net/xfrm.h>
97#include <net/inet_common.h>
98
99/*
100 * Build xmit assembly blocks
101 */
102
103struct icmp_bxm {
104 struct sk_buff *skb;
105 int offset;
106 int data_len;
107
108 struct {
109 struct icmphdr icmph;
110 __be32 times[3];
111 } data;
112 int head_len;
113 struct ip_options_data replyopts;
114};
115
116/* An array of errno for error messages from dest unreach. */
117/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
118
119const struct icmp_err icmp_err_convert[] = {
120 {
121 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
122 .fatal = 0,
123 },
124 {
125 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
126 .fatal = 0,
127 },
128 {
129 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
130 .fatal = 1,
131 },
132 {
133 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
134 .fatal = 1,
135 },
136 {
137 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
138 .fatal = 0,
139 },
140 {
141 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
142 .fatal = 0,
143 },
144 {
145 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
146 .fatal = 1,
147 },
148 {
149 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
150 .fatal = 1,
151 },
152 {
153 .errno = ENONET, /* ICMP_HOST_ISOLATED */
154 .fatal = 1,
155 },
156 {
157 .errno = ENETUNREACH, /* ICMP_NET_ANO */
158 .fatal = 1,
159 },
160 {
161 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
162 .fatal = 1,
163 },
164 {
165 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
166 .fatal = 0,
167 },
168 {
169 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
170 .fatal = 0,
171 },
172 {
173 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
174 .fatal = 1,
175 },
176 {
177 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
178 .fatal = 1,
179 },
180 {
181 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
182 .fatal = 1,
183 },
184};
185EXPORT_SYMBOL(icmp_err_convert);
186
187/*
188 * ICMP control array. This specifies what to do with each ICMP.
189 */
190
191struct icmp_control {
192 void (*handler)(struct sk_buff *skb);
193 short error; /* This ICMP is classed as an error message */
194};
195
196static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
197
198/*
199 * The ICMP socket(s). This is the most convenient way to flow control
200 * our ICMP output as well as maintain a clean interface throughout
201 * all layers. All Socketless IP sends will soon be gone.
202 *
203 * On SMP we have one ICMP socket per-cpu.
204 */
205static struct sock *icmp_sk(struct net *net)
206{
207 return net->ipv4.icmp_sk[smp_processor_id()];
208}
209
210static inline struct sock *icmp_xmit_lock(struct net *net)
211{
212 struct sock *sk;
213
214 local_bh_disable();
215
216 sk = icmp_sk(net);
217
218 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
219 /* This can happen if the output path signals a
220 * dst_link_failure() for an outgoing ICMP packet.
221 */
222 local_bh_enable();
223 return NULL;
224 }
225 return sk;
226}
227
228static inline void icmp_xmit_unlock(struct sock *sk)
229{
230 spin_unlock_bh(&sk->sk_lock.slock);
231}
232
233/*
234 * Send an ICMP frame.
235 */
236
237static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
238 struct flowi4 *fl4, int type, int code)
239{
240 struct dst_entry *dst = &rt->dst;
241 bool rc = true;
242
243 if (type > NR_ICMP_TYPES)
244 goto out;
245
246 /* Don't limit PMTU discovery. */
247 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
248 goto out;
249
250 /* No rate limit on loopback */
251 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
252 goto out;
253
254 /* Limit if icmp type is enabled in ratemask. */
255 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
256 if (!rt->peer)
257 rt_bind_peer(rt, fl4->daddr, 1);
258 rc = inet_peer_xrlim_allow(rt->peer,
259 net->ipv4.sysctl_icmp_ratelimit);
260 }
261out:
262 return rc;
263}
264
265/*
266 * Maintain the counters used in the SNMP statistics for outgoing ICMP
267 */
268void icmp_out_count(struct net *net, unsigned char type)
269{
270 ICMPMSGOUT_INC_STATS(net, type);
271 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
272}
273
274/*
275 * Checksum each fragment, and on the first include the headers and final
276 * checksum.
277 */
278static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
279 struct sk_buff *skb)
280{
281 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
282 __wsum csum;
283
284 csum = skb_copy_and_csum_bits(icmp_param->skb,
285 icmp_param->offset + offset,
286 to, len, 0);
287
288 skb->csum = csum_block_add(skb->csum, csum, odd);
289 if (icmp_pointers[icmp_param->data.icmph.type].error)
290 nf_ct_attach(skb, icmp_param->skb);
291 return 0;
292}
293
294static void icmp_push_reply(struct icmp_bxm *icmp_param,
295 struct flowi4 *fl4,
296 struct ipcm_cookie *ipc, struct rtable **rt)
297{
298 struct sock *sk;
299 struct sk_buff *skb;
300
301 sk = icmp_sk(dev_net((*rt)->dst.dev));
302 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
303 icmp_param->data_len+icmp_param->head_len,
304 icmp_param->head_len,
305 ipc, rt, MSG_DONTWAIT) < 0) {
306 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
307 ip_flush_pending_frames(sk);
308 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
309 struct icmphdr *icmph = icmp_hdr(skb);
310 __wsum csum = 0;
311 struct sk_buff *skb1;
312
313 skb_queue_walk(&sk->sk_write_queue, skb1) {
314 csum = csum_add(csum, skb1->csum);
315 }
316 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
317 (char *)icmph,
318 icmp_param->head_len, csum);
319 icmph->checksum = csum_fold(csum);
320 skb->ip_summed = CHECKSUM_NONE;
321 ip_push_pending_frames(sk, fl4);
322 }
323}
324
325/*
326 * Driving logic for building and sending ICMP messages.
327 */
328
329static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
330{
331 struct ipcm_cookie ipc;
332 struct rtable *rt = skb_rtable(skb);
333 struct net *net = dev_net(rt->dst.dev);
334 struct flowi4 fl4;
335 struct sock *sk;
336 struct inet_sock *inet;
337 __be32 daddr;
338
339 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
340 return;
341
342 sk = icmp_xmit_lock(net);
343 if (sk == NULL)
344 return;
345 inet = inet_sk(sk);
346
347 icmp_param->data.icmph.checksum = 0;
348
349 inet->tos = ip_hdr(skb)->tos;
350 daddr = ipc.addr = ip_hdr(skb)->saddr;
351 ipc.opt = NULL;
352 ipc.tx_flags = 0;
353 if (icmp_param->replyopts.opt.opt.optlen) {
354 ipc.opt = &icmp_param->replyopts.opt;
355 if (ipc.opt->opt.srr)
356 daddr = icmp_param->replyopts.opt.opt.faddr;
357 }
358 memset(&fl4, 0, sizeof(fl4));
359 fl4.daddr = daddr;
360 fl4.saddr = rt->rt_spec_dst;
361 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
362 fl4.flowi4_proto = IPPROTO_ICMP;
363 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
364 rt = ip_route_output_key(net, &fl4);
365 if (IS_ERR(rt))
366 goto out_unlock;
367 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
368 icmp_param->data.icmph.code))
369 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
370 ip_rt_put(rt);
371out_unlock:
372 icmp_xmit_unlock(sk);
373}
374
375static struct rtable *icmp_route_lookup(struct net *net,
376 struct flowi4 *fl4,
377 struct sk_buff *skb_in,
378 const struct iphdr *iph,
379 __be32 saddr, u8 tos,
380 int type, int code,
381 struct icmp_bxm *param)
382{
383 struct rtable *rt, *rt2;
384 struct flowi4 fl4_dec;
385 int err;
386
387 memset(fl4, 0, sizeof(*fl4));
388 fl4->daddr = (param->replyopts.opt.opt.srr ?
389 param->replyopts.opt.opt.faddr : iph->saddr);
390 fl4->saddr = saddr;
391 fl4->flowi4_tos = RT_TOS(tos);
392 fl4->flowi4_proto = IPPROTO_ICMP;
393 fl4->fl4_icmp_type = type;
394 fl4->fl4_icmp_code = code;
395 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
396 rt = __ip_route_output_key(net, fl4);
397 if (IS_ERR(rt))
398 return rt;
399
400 /* No need to clone since we're just using its address. */
401 rt2 = rt;
402
403 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
404 flowi4_to_flowi(fl4), NULL, 0);
405 if (!IS_ERR(rt)) {
406 if (rt != rt2)
407 return rt;
408 } else if (PTR_ERR(rt) == -EPERM) {
409 rt = NULL;
410 } else
411 return rt;
412
413 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
414 if (err)
415 goto relookup_failed;
416
417 if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
418 rt2 = __ip_route_output_key(net, &fl4_dec);
419 if (IS_ERR(rt2))
420 err = PTR_ERR(rt2);
421 } else {
422 struct flowi4 fl4_2 = {};
423 unsigned long orefdst;
424
425 fl4_2.daddr = fl4_dec.saddr;
426 rt2 = ip_route_output_key(net, &fl4_2);
427 if (IS_ERR(rt2)) {
428 err = PTR_ERR(rt2);
429 goto relookup_failed;
430 }
431 /* Ugh! */
432 orefdst = skb_in->_skb_refdst; /* save old refdst */
433 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
434 RT_TOS(tos), rt2->dst.dev);
435
436 dst_release(&rt2->dst);
437 rt2 = skb_rtable(skb_in);
438 skb_in->_skb_refdst = orefdst; /* restore old refdst */
439 }
440
441 if (err)
442 goto relookup_failed;
443
444 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
445 flowi4_to_flowi(&fl4_dec), NULL,
446 XFRM_LOOKUP_ICMP);
447 if (!IS_ERR(rt2)) {
448 dst_release(&rt->dst);
449 memcpy(fl4, &fl4_dec, sizeof(*fl4));
450 rt = rt2;
451 } else if (PTR_ERR(rt2) == -EPERM) {
452 if (rt)
453 dst_release(&rt->dst);
454 return rt2;
455 } else {
456 err = PTR_ERR(rt2);
457 goto relookup_failed;
458 }
459 return rt;
460
461relookup_failed:
462 if (rt)
463 return rt;
464 return ERR_PTR(err);
465}
466
467/*
468 * Send an ICMP message in response to a situation
469 *
470 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
471 * MAY send more (we do).
472 * MUST NOT change this header information.
473 * MUST NOT reply to a multicast/broadcast IP address.
474 * MUST NOT reply to a multicast/broadcast MAC address.
475 * MUST reply to only the first fragment.
476 */
477
478void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
479{
480 struct iphdr *iph;
481 int room;
482 struct icmp_bxm icmp_param;
483 struct rtable *rt = skb_rtable(skb_in);
484 struct ipcm_cookie ipc;
485 struct flowi4 fl4;
486 __be32 saddr;
487 u8 tos;
488 struct net *net;
489 struct sock *sk;
490
491 if (!rt)
492 goto out;
493 net = dev_net(rt->dst.dev);
494
495 /*
496 * Find the original header. It is expected to be valid, of course.
497 * Check this, icmp_send is called from the most obscure devices
498 * sometimes.
499 */
500 iph = ip_hdr(skb_in);
501
502 if ((u8 *)iph < skb_in->head ||
503 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
504 goto out;
505
506 /*
507 * No replies to physical multicast/broadcast
508 */
509 if (skb_in->pkt_type != PACKET_HOST)
510 goto out;
511
512 /*
513 * Now check at the protocol level
514 */
515 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
516 goto out;
517
518 /*
519 * Only reply to fragment 0. We byte re-order the constant
520 * mask for efficiency.
521 */
522 if (iph->frag_off & htons(IP_OFFSET))
523 goto out;
524
525 /*
526 * If we send an ICMP error to an ICMP error a mess would result..
527 */
528 if (icmp_pointers[type].error) {
529 /*
530 * We are an error, check if we are replying to an
531 * ICMP error
532 */
533 if (iph->protocol == IPPROTO_ICMP) {
534 u8 _inner_type, *itp;
535
536 itp = skb_header_pointer(skb_in,
537 skb_network_header(skb_in) +
538 (iph->ihl << 2) +
539 offsetof(struct icmphdr,
540 type) -
541 skb_in->data,
542 sizeof(_inner_type),
543 &_inner_type);
544 if (itp == NULL)
545 goto out;
546
547 /*
548 * Assume any unknown ICMP type is an error. This
549 * isn't specified by the RFC, but think about it..
550 */
551 if (*itp > NR_ICMP_TYPES ||
552 icmp_pointers[*itp].error)
553 goto out;
554 }
555 }
556
557 sk = icmp_xmit_lock(net);
558 if (sk == NULL)
559 return;
560
561 /*
562 * Construct source address and options.
563 */
564
565 saddr = iph->daddr;
566 if (!(rt->rt_flags & RTCF_LOCAL)) {
567 struct net_device *dev = NULL;
568
569 rcu_read_lock();
570 if (rt_is_input_route(rt) &&
571 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
572 dev = dev_get_by_index_rcu(net, rt->rt_iif);
573
574 if (dev)
575 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
576 else
577 saddr = 0;
578 rcu_read_unlock();
579 }
580
581 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
582 IPTOS_PREC_INTERNETCONTROL) :
583 iph->tos;
584
585 if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in))
586 goto out_unlock;
587
588
589 /*
590 * Prepare data for ICMP header.
591 */
592
593 icmp_param.data.icmph.type = type;
594 icmp_param.data.icmph.code = code;
595 icmp_param.data.icmph.un.gateway = info;
596 icmp_param.data.icmph.checksum = 0;
597 icmp_param.skb = skb_in;
598 icmp_param.offset = skb_network_offset(skb_in);
599 inet_sk(sk)->tos = tos;
600 ipc.addr = iph->saddr;
601 ipc.opt = &icmp_param.replyopts.opt;
602 ipc.tx_flags = 0;
603
604 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
605 type, code, &icmp_param);
606 if (IS_ERR(rt))
607 goto out_unlock;
608
609 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
610 goto ende;
611
612 /* RFC says return as much as we can without exceeding 576 bytes. */
613
614 room = dst_mtu(&rt->dst);
615 if (room > 576)
616 room = 576;
617 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
618 room -= sizeof(struct icmphdr);
619
620 icmp_param.data_len = skb_in->len - icmp_param.offset;
621 if (icmp_param.data_len > room)
622 icmp_param.data_len = room;
623 icmp_param.head_len = sizeof(struct icmphdr);
624
625 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
626ende:
627 ip_rt_put(rt);
628out_unlock:
629 icmp_xmit_unlock(sk);
630out:;
631}
632EXPORT_SYMBOL(icmp_send);
633
634
635/*
636 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
637 */
638
639static void icmp_unreach(struct sk_buff *skb)
640{
641 const struct iphdr *iph;
642 struct icmphdr *icmph;
643 int hash, protocol;
644 const struct net_protocol *ipprot;
645 u32 info = 0;
646 struct net *net;
647
648 net = dev_net(skb_dst(skb)->dev);
649
650 /*
651 * Incomplete header ?
652 * Only checks for the IP header, there should be an
653 * additional check for longer headers in upper levels.
654 */
655
656 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
657 goto out_err;
658
659 icmph = icmp_hdr(skb);
660 iph = (const struct iphdr *)skb->data;
661
662 if (iph->ihl < 5) /* Mangled header, drop. */
663 goto out_err;
664
665 if (icmph->type == ICMP_DEST_UNREACH) {
666 switch (icmph->code & 15) {
667 case ICMP_NET_UNREACH:
668 case ICMP_HOST_UNREACH:
669 case ICMP_PROT_UNREACH:
670 case ICMP_PORT_UNREACH:
671 break;
672 case ICMP_FRAG_NEEDED:
673 if (ipv4_config.no_pmtu_disc) {
674 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
675 &iph->daddr);
676 } else {
677 info = ip_rt_frag_needed(net, iph,
678 ntohs(icmph->un.frag.mtu),
679 skb->dev);
680 if (!info)
681 goto out;
682 }
683 break;
684 case ICMP_SR_FAILED:
685 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
686 &iph->daddr);
687 break;
688 default:
689 break;
690 }
691 if (icmph->code > NR_ICMP_UNREACH)
692 goto out;
693 } else if (icmph->type == ICMP_PARAMETERPROB)
694 info = ntohl(icmph->un.gateway) >> 24;
695
696 /*
697 * Throw it at our lower layers
698 *
699 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
700 * header.
701 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
702 * transport layer.
703 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
704 * transport layer.
705 */
706
707 /*
708 * Check the other end isn't violating RFC 1122. Some routers send
709 * bogus responses to broadcast frames. If you see this message
710 * first check your netmask matches at both ends, if it does then
711 * get the other vendor to fix their kit.
712 */
713
714 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
715 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
716 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
717 &ip_hdr(skb)->saddr,
718 icmph->type, icmph->code,
719 &iph->daddr, skb->dev->name);
720 goto out;
721 }
722
723 /* Checkin full IP header plus 8 bytes of protocol to
724 * avoid additional coding at protocol handlers.
725 */
726 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
727 goto out;
728
729 iph = (const struct iphdr *)skb->data;
730 protocol = iph->protocol;
731
732 /*
733 * Deliver ICMP message to raw sockets. Pretty useless feature?
734 */
735 raw_icmp_error(skb, protocol, info);
736
737 hash = protocol & (MAX_INET_PROTOS - 1);
738 rcu_read_lock();
739 ipprot = rcu_dereference(inet_protos[hash]);
740 if (ipprot && ipprot->err_handler)
741 ipprot->err_handler(skb, info);
742 rcu_read_unlock();
743
744out:
745 return;
746out_err:
747 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
748 goto out;
749}
750
751
752/*
753 * Handle ICMP_REDIRECT.
754 */
755
756static void icmp_redirect(struct sk_buff *skb)
757{
758 const struct iphdr *iph;
759
760 if (skb->len < sizeof(struct iphdr))
761 goto out_err;
762
763 /*
764 * Get the copied header of the packet that caused the redirect
765 */
766 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
767 goto out;
768
769 iph = (const struct iphdr *)skb->data;
770
771 switch (icmp_hdr(skb)->code & 7) {
772 case ICMP_REDIR_NET:
773 case ICMP_REDIR_NETTOS:
774 /*
775 * As per RFC recommendations now handle it as a host redirect.
776 */
777 case ICMP_REDIR_HOST:
778 case ICMP_REDIR_HOSTTOS:
779 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
780 icmp_hdr(skb)->un.gateway,
781 iph->saddr, skb->dev);
782 break;
783 }
784
785 /* Ping wants to see redirects.
786 * Let's pretend they are errors of sorts... */
787 if (iph->protocol == IPPROTO_ICMP &&
788 iph->ihl >= 5 &&
789 pskb_may_pull(skb, (iph->ihl<<2)+8)) {
790 ping_err(skb, icmp_hdr(skb)->un.gateway);
791 }
792
793out:
794 return;
795out_err:
796 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
797 goto out;
798}
799
800/*
801 * Handle ICMP_ECHO ("ping") requests.
802 *
803 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
804 * requests.
805 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
806 * included in the reply.
807 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
808 * echo requests, MUST have default=NOT.
809 * See also WRT handling of options once they are done and working.
810 */
811
812static void icmp_echo(struct sk_buff *skb)
813{
814 struct net *net;
815
816 net = dev_net(skb_dst(skb)->dev);
817 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
818 struct icmp_bxm icmp_param;
819
820 icmp_param.data.icmph = *icmp_hdr(skb);
821 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
822 icmp_param.skb = skb;
823 icmp_param.offset = 0;
824 icmp_param.data_len = skb->len;
825 icmp_param.head_len = sizeof(struct icmphdr);
826 icmp_reply(&icmp_param, skb);
827 }
828}
829
830/*
831 * Handle ICMP Timestamp requests.
832 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
833 * SHOULD be in the kernel for minimum random latency.
834 * MUST be accurate to a few minutes.
835 * MUST be updated at least at 15Hz.
836 */
837static void icmp_timestamp(struct sk_buff *skb)
838{
839 struct timespec tv;
840 struct icmp_bxm icmp_param;
841 /*
842 * Too short.
843 */
844 if (skb->len < 4)
845 goto out_err;
846
847 /*
848 * Fill in the current time as ms since midnight UT:
849 */
850 getnstimeofday(&tv);
851 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
852 tv.tv_nsec / NSEC_PER_MSEC);
853 icmp_param.data.times[2] = icmp_param.data.times[1];
854 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
855 BUG();
856 icmp_param.data.icmph = *icmp_hdr(skb);
857 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
858 icmp_param.data.icmph.code = 0;
859 icmp_param.skb = skb;
860 icmp_param.offset = 0;
861 icmp_param.data_len = 0;
862 icmp_param.head_len = sizeof(struct icmphdr) + 12;
863 icmp_reply(&icmp_param, skb);
864out:
865 return;
866out_err:
867 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
868 goto out;
869}
870
871
872/*
873 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
874 *
875 * RFC1122 (3.2.2.9). A host MUST only send replies to
876 * ADDRESS_MASK requests if it's been configured as an address mask
877 * agent. Receiving a request doesn't constitute implicit permission to
878 * act as one. Of course, implementing this correctly requires (SHOULD)
879 * a way to turn the functionality on and off. Another one for sysctl(),
880 * I guess. -- MS
881 *
882 * RFC1812 (4.3.3.9). A router MUST implement it.
883 * A router SHOULD have switch turning it on/off.
884 * This switch MUST be ON by default.
885 *
886 * Gratuitous replies, zero-source replies are not implemented,
887 * that complies with RFC. DO NOT implement them!!! All the idea
888 * of broadcast addrmask replies as specified in RFC950 is broken.
889 * The problem is that it is not uncommon to have several prefixes
890 * on one physical interface. Moreover, addrmask agent can even be
891 * not aware of existing another prefixes.
892 * If source is zero, addrmask agent cannot choose correct prefix.
893 * Gratuitous mask announcements suffer from the same problem.
894 * RFC1812 explains it, but still allows to use ADDRMASK,
895 * that is pretty silly. --ANK
896 *
897 * All these rules are so bizarre, that I removed kernel addrmask
898 * support at all. It is wrong, it is obsolete, nobody uses it in
899 * any case. --ANK
900 *
901 * Furthermore you can do it with a usermode address agent program
902 * anyway...
903 */
904
905static void icmp_address(struct sk_buff *skb)
906{
907#if 0
908 net_dbg_ratelimited("a guy asks for address mask. Who is it?\n");
909#endif
910}
911
912/*
913 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
914 * loudly if an inconsistency is found.
915 * called with rcu_read_lock()
916 */
917
918static void icmp_address_reply(struct sk_buff *skb)
919{
920 struct rtable *rt = skb_rtable(skb);
921 struct net_device *dev = skb->dev;
922 struct in_device *in_dev;
923 struct in_ifaddr *ifa;
924
925 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
926 return;
927
928 in_dev = __in_dev_get_rcu(dev);
929 if (!in_dev)
930 return;
931
932 if (in_dev->ifa_list &&
933 IN_DEV_LOG_MARTIANS(in_dev) &&
934 IN_DEV_FORWARD(in_dev)) {
935 __be32 _mask, *mp;
936
937 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
938 BUG_ON(mp == NULL);
939 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
940 if (*mp == ifa->ifa_mask &&
941 inet_ifa_match(ip_hdr(skb)->saddr, ifa))
942 break;
943 }
944 if (!ifa)
945 net_info_ratelimited("Wrong address mask %pI4 from %s/%pI4\n",
946 mp,
947 dev->name, &ip_hdr(skb)->saddr);
948 }
949}
950
951static void icmp_discard(struct sk_buff *skb)
952{
953}
954
955/*
956 * Deal with incoming ICMP packets.
957 */
958int icmp_rcv(struct sk_buff *skb)
959{
960 struct icmphdr *icmph;
961 struct rtable *rt = skb_rtable(skb);
962 struct net *net = dev_net(rt->dst.dev);
963
964 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
965 struct sec_path *sp = skb_sec_path(skb);
966 int nh;
967
968 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
969 XFRM_STATE_ICMP))
970 goto drop;
971
972 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
973 goto drop;
974
975 nh = skb_network_offset(skb);
976 skb_set_network_header(skb, sizeof(*icmph));
977
978 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
979 goto drop;
980
981 skb_set_network_header(skb, nh);
982 }
983
984 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
985
986 switch (skb->ip_summed) {
987 case CHECKSUM_COMPLETE:
988 if (!csum_fold(skb->csum))
989 break;
990 /* fall through */
991 case CHECKSUM_NONE:
992 skb->csum = 0;
993 if (__skb_checksum_complete(skb))
994 goto error;
995 }
996
997 if (!pskb_pull(skb, sizeof(*icmph)))
998 goto error;
999
1000 icmph = icmp_hdr(skb);
1001
1002 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
1003 /*
1004 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1005 *
1006 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1007 * discarded.
1008 */
1009 if (icmph->type > NR_ICMP_TYPES)
1010 goto error;
1011
1012
1013 /*
1014 * Parse the ICMP message
1015 */
1016
1017 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1018 /*
1019 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1020 * silently ignored (we let user decide with a sysctl).
1021 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1022 * discarded if to broadcast/multicast.
1023 */
1024 if ((icmph->type == ICMP_ECHO ||
1025 icmph->type == ICMP_TIMESTAMP) &&
1026 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1027 goto error;
1028 }
1029 if (icmph->type != ICMP_ECHO &&
1030 icmph->type != ICMP_TIMESTAMP &&
1031 icmph->type != ICMP_ADDRESS &&
1032 icmph->type != ICMP_ADDRESSREPLY) {
1033 goto error;
1034 }
1035 }
1036
1037 icmp_pointers[icmph->type].handler(skb);
1038
1039drop:
1040 kfree_skb(skb);
1041 return 0;
1042error:
1043 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1044 goto drop;
1045}
1046
1047/*
1048 * This table is the definition of how we handle ICMP.
1049 */
1050static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1051 [ICMP_ECHOREPLY] = {
1052 .handler = ping_rcv,
1053 },
1054 [1] = {
1055 .handler = icmp_discard,
1056 .error = 1,
1057 },
1058 [2] = {
1059 .handler = icmp_discard,
1060 .error = 1,
1061 },
1062 [ICMP_DEST_UNREACH] = {
1063 .handler = icmp_unreach,
1064 .error = 1,
1065 },
1066 [ICMP_SOURCE_QUENCH] = {
1067 .handler = icmp_unreach,
1068 .error = 1,
1069 },
1070 [ICMP_REDIRECT] = {
1071 .handler = icmp_redirect,
1072 .error = 1,
1073 },
1074 [6] = {
1075 .handler = icmp_discard,
1076 .error = 1,
1077 },
1078 [7] = {
1079 .handler = icmp_discard,
1080 .error = 1,
1081 },
1082 [ICMP_ECHO] = {
1083 .handler = icmp_echo,
1084 },
1085 [9] = {
1086 .handler = icmp_discard,
1087 .error = 1,
1088 },
1089 [10] = {
1090 .handler = icmp_discard,
1091 .error = 1,
1092 },
1093 [ICMP_TIME_EXCEEDED] = {
1094 .handler = icmp_unreach,
1095 .error = 1,
1096 },
1097 [ICMP_PARAMETERPROB] = {
1098 .handler = icmp_unreach,
1099 .error = 1,
1100 },
1101 [ICMP_TIMESTAMP] = {
1102 .handler = icmp_timestamp,
1103 },
1104 [ICMP_TIMESTAMPREPLY] = {
1105 .handler = icmp_discard,
1106 },
1107 [ICMP_INFO_REQUEST] = {
1108 .handler = icmp_discard,
1109 },
1110 [ICMP_INFO_REPLY] = {
1111 .handler = icmp_discard,
1112 },
1113 [ICMP_ADDRESS] = {
1114 .handler = icmp_address,
1115 },
1116 [ICMP_ADDRESSREPLY] = {
1117 .handler = icmp_address_reply,
1118 },
1119};
1120
1121static void __net_exit icmp_sk_exit(struct net *net)
1122{
1123 int i;
1124
1125 for_each_possible_cpu(i)
1126 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1127 kfree(net->ipv4.icmp_sk);
1128 net->ipv4.icmp_sk = NULL;
1129}
1130
1131static int __net_init icmp_sk_init(struct net *net)
1132{
1133 int i, err;
1134
1135 net->ipv4.icmp_sk =
1136 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1137 if (net->ipv4.icmp_sk == NULL)
1138 return -ENOMEM;
1139
1140 for_each_possible_cpu(i) {
1141 struct sock *sk;
1142
1143 err = inet_ctl_sock_create(&sk, PF_INET,
1144 SOCK_RAW, IPPROTO_ICMP, net);
1145 if (err < 0)
1146 goto fail;
1147
1148 net->ipv4.icmp_sk[i] = sk;
1149
1150 /* Enough space for 2 64K ICMP packets, including
1151 * sk_buff/skb_shared_info struct overhead.
1152 */
1153 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1154
1155 /*
1156 * Speedup sock_wfree()
1157 */
1158 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1159 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1160 }
1161
1162 /* Control parameters for ECHO replies. */
1163 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1164 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1165
1166 /* Control parameter - ignore bogus broadcast responses? */
1167 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1168
1169 /*
1170 * Configurable global rate limit.
1171 *
1172 * ratelimit defines tokens/packet consumed for dst->rate_token
1173 * bucket ratemask defines which icmp types are ratelimited by
1174 * setting it's bit position.
1175 *
1176 * default:
1177 * dest unreachable (3), source quench (4),
1178 * time exceeded (11), parameter problem (12)
1179 */
1180
1181 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1182 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1183 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1184
1185 return 0;
1186
1187fail:
1188 for_each_possible_cpu(i)
1189 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1190 kfree(net->ipv4.icmp_sk);
1191 return err;
1192}
1193
1194static struct pernet_operations __net_initdata icmp_sk_ops = {
1195 .init = icmp_sk_init,
1196 .exit = icmp_sk_exit,
1197};
1198
1199int __init icmp_init(void)
1200{
1201 return register_pernet_subsys(&icmp_sk_ops);
1202}
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66
67#include <linux/module.h>
68#include <linux/types.h>
69#include <linux/jiffies.h>
70#include <linux/kernel.h>
71#include <linux/fcntl.h>
72#include <linux/socket.h>
73#include <linux/in.h>
74#include <linux/inet.h>
75#include <linux/inetdevice.h>
76#include <linux/netdevice.h>
77#include <linux/string.h>
78#include <linux/netfilter_ipv4.h>
79#include <linux/slab.h>
80#include <net/snmp.h>
81#include <net/ip.h>
82#include <net/route.h>
83#include <net/protocol.h>
84#include <net/icmp.h>
85#include <net/tcp.h>
86#include <net/udp.h>
87#include <net/raw.h>
88#include <net/ping.h>
89#include <linux/skbuff.h>
90#include <net/sock.h>
91#include <linux/errno.h>
92#include <linux/timer.h>
93#include <linux/init.h>
94#include <linux/uaccess.h>
95#include <net/checksum.h>
96#include <net/xfrm.h>
97#include <net/inet_common.h>
98#include <net/ip_fib.h>
99#include <net/l3mdev.h>
100
101/*
102 * Build xmit assembly blocks
103 */
104
105struct icmp_bxm {
106 struct sk_buff *skb;
107 int offset;
108 int data_len;
109
110 struct {
111 struct icmphdr icmph;
112 __be32 times[3];
113 } data;
114 int head_len;
115 struct ip_options_data replyopts;
116};
117
118/* An array of errno for error messages from dest unreach. */
119/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
120
121const struct icmp_err icmp_err_convert[] = {
122 {
123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
124 .fatal = 0,
125 },
126 {
127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
128 .fatal = 0,
129 },
130 {
131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
132 .fatal = 1,
133 },
134 {
135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
136 .fatal = 1,
137 },
138 {
139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
140 .fatal = 0,
141 },
142 {
143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
144 .fatal = 0,
145 },
146 {
147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
148 .fatal = 1,
149 },
150 {
151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
152 .fatal = 1,
153 },
154 {
155 .errno = ENONET, /* ICMP_HOST_ISOLATED */
156 .fatal = 1,
157 },
158 {
159 .errno = ENETUNREACH, /* ICMP_NET_ANO */
160 .fatal = 1,
161 },
162 {
163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
164 .fatal = 1,
165 },
166 {
167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
168 .fatal = 0,
169 },
170 {
171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
172 .fatal = 0,
173 },
174 {
175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
176 .fatal = 1,
177 },
178 {
179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
180 .fatal = 1,
181 },
182 {
183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
184 .fatal = 1,
185 },
186};
187EXPORT_SYMBOL(icmp_err_convert);
188
189/*
190 * ICMP control array. This specifies what to do with each ICMP.
191 */
192
193struct icmp_control {
194 bool (*handler)(struct sk_buff *skb);
195 short error; /* This ICMP is classed as an error message */
196};
197
198static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
199
200/*
201 * The ICMP socket(s). This is the most convenient way to flow control
202 * our ICMP output as well as maintain a clean interface throughout
203 * all layers. All Socketless IP sends will soon be gone.
204 *
205 * On SMP we have one ICMP socket per-cpu.
206 */
207static struct sock *icmp_sk(struct net *net)
208{
209 return *this_cpu_ptr(net->ipv4.icmp_sk);
210}
211
212static inline struct sock *icmp_xmit_lock(struct net *net)
213{
214 struct sock *sk;
215
216 local_bh_disable();
217
218 sk = icmp_sk(net);
219
220 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
221 /* This can happen if the output path signals a
222 * dst_link_failure() for an outgoing ICMP packet.
223 */
224 local_bh_enable();
225 return NULL;
226 }
227 return sk;
228}
229
230static inline void icmp_xmit_unlock(struct sock *sk)
231{
232 spin_unlock_bh(&sk->sk_lock.slock);
233}
234
235int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
236int sysctl_icmp_msgs_burst __read_mostly = 50;
237
238static struct {
239 spinlock_t lock;
240 u32 credit;
241 u32 stamp;
242} icmp_global = {
243 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
244};
245
246/**
247 * icmp_global_allow - Are we allowed to send one more ICMP message ?
248 *
249 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
250 * Returns false if we reached the limit and can not send another packet.
251 * Note: called with BH disabled
252 */
253bool icmp_global_allow(void)
254{
255 u32 credit, delta, incr = 0, now = (u32)jiffies;
256 bool rc = false;
257
258 /* Check if token bucket is empty and cannot be refilled
259 * without taking the spinlock.
260 */
261 if (!icmp_global.credit) {
262 delta = min_t(u32, now - icmp_global.stamp, HZ);
263 if (delta < HZ / 50)
264 return false;
265 }
266
267 spin_lock(&icmp_global.lock);
268 delta = min_t(u32, now - icmp_global.stamp, HZ);
269 if (delta >= HZ / 50) {
270 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
271 if (incr)
272 icmp_global.stamp = now;
273 }
274 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
275 if (credit) {
276 credit--;
277 rc = true;
278 }
279 icmp_global.credit = credit;
280 spin_unlock(&icmp_global.lock);
281 return rc;
282}
283EXPORT_SYMBOL(icmp_global_allow);
284
285/*
286 * Send an ICMP frame.
287 */
288
289static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
290 struct flowi4 *fl4, int type, int code)
291{
292 struct dst_entry *dst = &rt->dst;
293 bool rc = true;
294
295 if (type > NR_ICMP_TYPES)
296 goto out;
297
298 /* Don't limit PMTU discovery. */
299 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
300 goto out;
301
302 /* No rate limit on loopback */
303 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
304 goto out;
305
306 /* Limit if icmp type is enabled in ratemask. */
307 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
308 goto out;
309
310 rc = false;
311 if (icmp_global_allow()) {
312 int vif = l3mdev_master_ifindex(dst->dev);
313 struct inet_peer *peer;
314
315 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
316 rc = inet_peer_xrlim_allow(peer,
317 net->ipv4.sysctl_icmp_ratelimit);
318 if (peer)
319 inet_putpeer(peer);
320 }
321out:
322 return rc;
323}
324
325/*
326 * Maintain the counters used in the SNMP statistics for outgoing ICMP
327 */
328void icmp_out_count(struct net *net, unsigned char type)
329{
330 ICMPMSGOUT_INC_STATS(net, type);
331 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
332}
333
334/*
335 * Checksum each fragment, and on the first include the headers and final
336 * checksum.
337 */
338static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
339 struct sk_buff *skb)
340{
341 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
342 __wsum csum;
343
344 csum = skb_copy_and_csum_bits(icmp_param->skb,
345 icmp_param->offset + offset,
346 to, len, 0);
347
348 skb->csum = csum_block_add(skb->csum, csum, odd);
349 if (icmp_pointers[icmp_param->data.icmph.type].error)
350 nf_ct_attach(skb, icmp_param->skb);
351 return 0;
352}
353
354static void icmp_push_reply(struct icmp_bxm *icmp_param,
355 struct flowi4 *fl4,
356 struct ipcm_cookie *ipc, struct rtable **rt)
357{
358 struct sock *sk;
359 struct sk_buff *skb;
360
361 sk = icmp_sk(dev_net((*rt)->dst.dev));
362 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
363 icmp_param->data_len+icmp_param->head_len,
364 icmp_param->head_len,
365 ipc, rt, MSG_DONTWAIT) < 0) {
366 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
367 ip_flush_pending_frames(sk);
368 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
369 struct icmphdr *icmph = icmp_hdr(skb);
370 __wsum csum = 0;
371 struct sk_buff *skb1;
372
373 skb_queue_walk(&sk->sk_write_queue, skb1) {
374 csum = csum_add(csum, skb1->csum);
375 }
376 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
377 (char *)icmph,
378 icmp_param->head_len, csum);
379 icmph->checksum = csum_fold(csum);
380 skb->ip_summed = CHECKSUM_NONE;
381 ip_push_pending_frames(sk, fl4);
382 }
383}
384
385/*
386 * Driving logic for building and sending ICMP messages.
387 */
388
389static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
390{
391 struct ipcm_cookie ipc;
392 struct rtable *rt = skb_rtable(skb);
393 struct net *net = dev_net(rt->dst.dev);
394 struct flowi4 fl4;
395 struct sock *sk;
396 struct inet_sock *inet;
397 __be32 daddr, saddr;
398 u32 mark = IP4_REPLY_MARK(net, skb->mark);
399
400 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
401 return;
402
403 sk = icmp_xmit_lock(net);
404 if (!sk)
405 return;
406 inet = inet_sk(sk);
407
408 icmp_param->data.icmph.checksum = 0;
409
410 inet->tos = ip_hdr(skb)->tos;
411 sk->sk_mark = mark;
412 daddr = ipc.addr = ip_hdr(skb)->saddr;
413 saddr = fib_compute_spec_dst(skb);
414 ipc.opt = NULL;
415 ipc.tx_flags = 0;
416 ipc.ttl = 0;
417 ipc.tos = -1;
418
419 if (icmp_param->replyopts.opt.opt.optlen) {
420 ipc.opt = &icmp_param->replyopts.opt;
421 if (ipc.opt->opt.srr)
422 daddr = icmp_param->replyopts.opt.opt.faddr;
423 }
424 memset(&fl4, 0, sizeof(fl4));
425 fl4.daddr = daddr;
426 fl4.saddr = saddr;
427 fl4.flowi4_mark = mark;
428 fl4.flowi4_uid = sock_net_uid(net, NULL);
429 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
430 fl4.flowi4_proto = IPPROTO_ICMP;
431 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
432 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
433 rt = ip_route_output_key(net, &fl4);
434 if (IS_ERR(rt))
435 goto out_unlock;
436 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
437 icmp_param->data.icmph.code))
438 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
439 ip_rt_put(rt);
440out_unlock:
441 icmp_xmit_unlock(sk);
442}
443
444#ifdef CONFIG_IP_ROUTE_MULTIPATH
445
446/* Source and destination is swapped. See ip_multipath_icmp_hash */
447static int icmp_multipath_hash_skb(const struct sk_buff *skb)
448{
449 const struct iphdr *iph = ip_hdr(skb);
450
451 return fib_multipath_hash(iph->daddr, iph->saddr);
452}
453
454#else
455
456#define icmp_multipath_hash_skb(skb) (-1)
457
458#endif
459
460static struct rtable *icmp_route_lookup(struct net *net,
461 struct flowi4 *fl4,
462 struct sk_buff *skb_in,
463 const struct iphdr *iph,
464 __be32 saddr, u8 tos, u32 mark,
465 int type, int code,
466 struct icmp_bxm *param)
467{
468 struct rtable *rt, *rt2;
469 struct flowi4 fl4_dec;
470 int err;
471
472 memset(fl4, 0, sizeof(*fl4));
473 fl4->daddr = (param->replyopts.opt.opt.srr ?
474 param->replyopts.opt.opt.faddr : iph->saddr);
475 fl4->saddr = saddr;
476 fl4->flowi4_mark = mark;
477 fl4->flowi4_uid = sock_net_uid(net, NULL);
478 fl4->flowi4_tos = RT_TOS(tos);
479 fl4->flowi4_proto = IPPROTO_ICMP;
480 fl4->fl4_icmp_type = type;
481 fl4->fl4_icmp_code = code;
482 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev);
483
484 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
485 rt = __ip_route_output_key_hash(net, fl4,
486 icmp_multipath_hash_skb(skb_in));
487 if (IS_ERR(rt))
488 return rt;
489
490 /* No need to clone since we're just using its address. */
491 rt2 = rt;
492
493 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
494 flowi4_to_flowi(fl4), NULL, 0);
495 if (!IS_ERR(rt)) {
496 if (rt != rt2)
497 return rt;
498 } else if (PTR_ERR(rt) == -EPERM) {
499 rt = NULL;
500 } else
501 return rt;
502
503 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
504 if (err)
505 goto relookup_failed;
506
507 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev,
508 fl4_dec.saddr) == RTN_LOCAL) {
509 rt2 = __ip_route_output_key(net, &fl4_dec);
510 if (IS_ERR(rt2))
511 err = PTR_ERR(rt2);
512 } else {
513 struct flowi4 fl4_2 = {};
514 unsigned long orefdst;
515
516 fl4_2.daddr = fl4_dec.saddr;
517 rt2 = ip_route_output_key(net, &fl4_2);
518 if (IS_ERR(rt2)) {
519 err = PTR_ERR(rt2);
520 goto relookup_failed;
521 }
522 /* Ugh! */
523 orefdst = skb_in->_skb_refdst; /* save old refdst */
524 skb_dst_set(skb_in, NULL);
525 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
526 RT_TOS(tos), rt2->dst.dev);
527
528 dst_release(&rt2->dst);
529 rt2 = skb_rtable(skb_in);
530 skb_in->_skb_refdst = orefdst; /* restore old refdst */
531 }
532
533 if (err)
534 goto relookup_failed;
535
536 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
537 flowi4_to_flowi(&fl4_dec), NULL,
538 XFRM_LOOKUP_ICMP);
539 if (!IS_ERR(rt2)) {
540 dst_release(&rt->dst);
541 memcpy(fl4, &fl4_dec, sizeof(*fl4));
542 rt = rt2;
543 } else if (PTR_ERR(rt2) == -EPERM) {
544 if (rt)
545 dst_release(&rt->dst);
546 return rt2;
547 } else {
548 err = PTR_ERR(rt2);
549 goto relookup_failed;
550 }
551 return rt;
552
553relookup_failed:
554 if (rt)
555 return rt;
556 return ERR_PTR(err);
557}
558
559/*
560 * Send an ICMP message in response to a situation
561 *
562 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
563 * MAY send more (we do).
564 * MUST NOT change this header information.
565 * MUST NOT reply to a multicast/broadcast IP address.
566 * MUST NOT reply to a multicast/broadcast MAC address.
567 * MUST reply to only the first fragment.
568 */
569
570void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
571{
572 struct iphdr *iph;
573 int room;
574 struct icmp_bxm *icmp_param;
575 struct rtable *rt = skb_rtable(skb_in);
576 struct ipcm_cookie ipc;
577 struct flowi4 fl4;
578 __be32 saddr;
579 u8 tos;
580 u32 mark;
581 struct net *net;
582 struct sock *sk;
583
584 if (!rt)
585 goto out;
586 net = dev_net(rt->dst.dev);
587
588 /*
589 * Find the original header. It is expected to be valid, of course.
590 * Check this, icmp_send is called from the most obscure devices
591 * sometimes.
592 */
593 iph = ip_hdr(skb_in);
594
595 if ((u8 *)iph < skb_in->head ||
596 (skb_network_header(skb_in) + sizeof(*iph)) >
597 skb_tail_pointer(skb_in))
598 goto out;
599
600 /*
601 * No replies to physical multicast/broadcast
602 */
603 if (skb_in->pkt_type != PACKET_HOST)
604 goto out;
605
606 /*
607 * Now check at the protocol level
608 */
609 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
610 goto out;
611
612 /*
613 * Only reply to fragment 0. We byte re-order the constant
614 * mask for efficiency.
615 */
616 if (iph->frag_off & htons(IP_OFFSET))
617 goto out;
618
619 /*
620 * If we send an ICMP error to an ICMP error a mess would result..
621 */
622 if (icmp_pointers[type].error) {
623 /*
624 * We are an error, check if we are replying to an
625 * ICMP error
626 */
627 if (iph->protocol == IPPROTO_ICMP) {
628 u8 _inner_type, *itp;
629
630 itp = skb_header_pointer(skb_in,
631 skb_network_header(skb_in) +
632 (iph->ihl << 2) +
633 offsetof(struct icmphdr,
634 type) -
635 skb_in->data,
636 sizeof(_inner_type),
637 &_inner_type);
638 if (!itp)
639 goto out;
640
641 /*
642 * Assume any unknown ICMP type is an error. This
643 * isn't specified by the RFC, but think about it..
644 */
645 if (*itp > NR_ICMP_TYPES ||
646 icmp_pointers[*itp].error)
647 goto out;
648 }
649 }
650
651 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
652 if (!icmp_param)
653 return;
654
655 sk = icmp_xmit_lock(net);
656 if (!sk)
657 goto out_free;
658
659 /*
660 * Construct source address and options.
661 */
662
663 saddr = iph->daddr;
664 if (!(rt->rt_flags & RTCF_LOCAL)) {
665 struct net_device *dev = NULL;
666
667 rcu_read_lock();
668 if (rt_is_input_route(rt) &&
669 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
670 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
671
672 if (dev)
673 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
674 else
675 saddr = 0;
676 rcu_read_unlock();
677 }
678
679 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
680 IPTOS_PREC_INTERNETCONTROL) :
681 iph->tos;
682 mark = IP4_REPLY_MARK(net, skb_in->mark);
683
684 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
685 goto out_unlock;
686
687
688 /*
689 * Prepare data for ICMP header.
690 */
691
692 icmp_param->data.icmph.type = type;
693 icmp_param->data.icmph.code = code;
694 icmp_param->data.icmph.un.gateway = info;
695 icmp_param->data.icmph.checksum = 0;
696 icmp_param->skb = skb_in;
697 icmp_param->offset = skb_network_offset(skb_in);
698 inet_sk(sk)->tos = tos;
699 sk->sk_mark = mark;
700 ipc.addr = iph->saddr;
701 ipc.opt = &icmp_param->replyopts.opt;
702 ipc.tx_flags = 0;
703 ipc.ttl = 0;
704 ipc.tos = -1;
705
706 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
707 type, code, icmp_param);
708 if (IS_ERR(rt))
709 goto out_unlock;
710
711 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
712 goto ende;
713
714 /* RFC says return as much as we can without exceeding 576 bytes. */
715
716 room = dst_mtu(&rt->dst);
717 if (room > 576)
718 room = 576;
719 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
720 room -= sizeof(struct icmphdr);
721
722 icmp_param->data_len = skb_in->len - icmp_param->offset;
723 if (icmp_param->data_len > room)
724 icmp_param->data_len = room;
725 icmp_param->head_len = sizeof(struct icmphdr);
726
727 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
728ende:
729 ip_rt_put(rt);
730out_unlock:
731 icmp_xmit_unlock(sk);
732out_free:
733 kfree(icmp_param);
734out:;
735}
736EXPORT_SYMBOL(icmp_send);
737
738
739static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
740{
741 const struct iphdr *iph = (const struct iphdr *) skb->data;
742 const struct net_protocol *ipprot;
743 int protocol = iph->protocol;
744
745 /* Checkin full IP header plus 8 bytes of protocol to
746 * avoid additional coding at protocol handlers.
747 */
748 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
749 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
750 return;
751 }
752
753 raw_icmp_error(skb, protocol, info);
754
755 ipprot = rcu_dereference(inet_protos[protocol]);
756 if (ipprot && ipprot->err_handler)
757 ipprot->err_handler(skb, info);
758}
759
760static bool icmp_tag_validation(int proto)
761{
762 bool ok;
763
764 rcu_read_lock();
765 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
766 rcu_read_unlock();
767 return ok;
768}
769
770/*
771 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
772 * ICMP_PARAMETERPROB.
773 */
774
775static bool icmp_unreach(struct sk_buff *skb)
776{
777 const struct iphdr *iph;
778 struct icmphdr *icmph;
779 struct net *net;
780 u32 info = 0;
781
782 net = dev_net(skb_dst(skb)->dev);
783
784 /*
785 * Incomplete header ?
786 * Only checks for the IP header, there should be an
787 * additional check for longer headers in upper levels.
788 */
789
790 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
791 goto out_err;
792
793 icmph = icmp_hdr(skb);
794 iph = (const struct iphdr *)skb->data;
795
796 if (iph->ihl < 5) /* Mangled header, drop. */
797 goto out_err;
798
799 if (icmph->type == ICMP_DEST_UNREACH) {
800 switch (icmph->code & 15) {
801 case ICMP_NET_UNREACH:
802 case ICMP_HOST_UNREACH:
803 case ICMP_PROT_UNREACH:
804 case ICMP_PORT_UNREACH:
805 break;
806 case ICMP_FRAG_NEEDED:
807 /* for documentation of the ip_no_pmtu_disc
808 * values please see
809 * Documentation/networking/ip-sysctl.txt
810 */
811 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
812 default:
813 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
814 &iph->daddr);
815 break;
816 case 2:
817 goto out;
818 case 3:
819 if (!icmp_tag_validation(iph->protocol))
820 goto out;
821 /* fall through */
822 case 0:
823 info = ntohs(icmph->un.frag.mtu);
824 }
825 break;
826 case ICMP_SR_FAILED:
827 net_dbg_ratelimited("%pI4: Source Route Failed\n",
828 &iph->daddr);
829 break;
830 default:
831 break;
832 }
833 if (icmph->code > NR_ICMP_UNREACH)
834 goto out;
835 } else if (icmph->type == ICMP_PARAMETERPROB)
836 info = ntohl(icmph->un.gateway) >> 24;
837
838 /*
839 * Throw it at our lower layers
840 *
841 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
842 * header.
843 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
844 * transport layer.
845 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
846 * transport layer.
847 */
848
849 /*
850 * Check the other end isn't violating RFC 1122. Some routers send
851 * bogus responses to broadcast frames. If you see this message
852 * first check your netmask matches at both ends, if it does then
853 * get the other vendor to fix their kit.
854 */
855
856 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
857 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
858 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
859 &ip_hdr(skb)->saddr,
860 icmph->type, icmph->code,
861 &iph->daddr, skb->dev->name);
862 goto out;
863 }
864
865 icmp_socket_deliver(skb, info);
866
867out:
868 return true;
869out_err:
870 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
871 return false;
872}
873
874
875/*
876 * Handle ICMP_REDIRECT.
877 */
878
879static bool icmp_redirect(struct sk_buff *skb)
880{
881 if (skb->len < sizeof(struct iphdr)) {
882 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
883 return false;
884 }
885
886 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
887 /* there aught to be a stat */
888 return false;
889 }
890
891 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
892 return true;
893}
894
895/*
896 * Handle ICMP_ECHO ("ping") requests.
897 *
898 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
899 * requests.
900 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
901 * included in the reply.
902 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
903 * echo requests, MUST have default=NOT.
904 * See also WRT handling of options once they are done and working.
905 */
906
907static bool icmp_echo(struct sk_buff *skb)
908{
909 struct net *net;
910
911 net = dev_net(skb_dst(skb)->dev);
912 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
913 struct icmp_bxm icmp_param;
914
915 icmp_param.data.icmph = *icmp_hdr(skb);
916 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
917 icmp_param.skb = skb;
918 icmp_param.offset = 0;
919 icmp_param.data_len = skb->len;
920 icmp_param.head_len = sizeof(struct icmphdr);
921 icmp_reply(&icmp_param, skb);
922 }
923 /* should there be an ICMP stat for ignored echos? */
924 return true;
925}
926
927/*
928 * Handle ICMP Timestamp requests.
929 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
930 * SHOULD be in the kernel for minimum random latency.
931 * MUST be accurate to a few minutes.
932 * MUST be updated at least at 15Hz.
933 */
934static bool icmp_timestamp(struct sk_buff *skb)
935{
936 struct icmp_bxm icmp_param;
937 /*
938 * Too short.
939 */
940 if (skb->len < 4)
941 goto out_err;
942
943 /*
944 * Fill in the current time as ms since midnight UT:
945 */
946 icmp_param.data.times[1] = inet_current_timestamp();
947 icmp_param.data.times[2] = icmp_param.data.times[1];
948 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
949 BUG();
950 icmp_param.data.icmph = *icmp_hdr(skb);
951 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
952 icmp_param.data.icmph.code = 0;
953 icmp_param.skb = skb;
954 icmp_param.offset = 0;
955 icmp_param.data_len = 0;
956 icmp_param.head_len = sizeof(struct icmphdr) + 12;
957 icmp_reply(&icmp_param, skb);
958 return true;
959
960out_err:
961 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
962 return false;
963}
964
965static bool icmp_discard(struct sk_buff *skb)
966{
967 /* pretend it was a success */
968 return true;
969}
970
971/*
972 * Deal with incoming ICMP packets.
973 */
974int icmp_rcv(struct sk_buff *skb)
975{
976 struct icmphdr *icmph;
977 struct rtable *rt = skb_rtable(skb);
978 struct net *net = dev_net(rt->dst.dev);
979 bool success;
980
981 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
982 struct sec_path *sp = skb_sec_path(skb);
983 int nh;
984
985 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
986 XFRM_STATE_ICMP))
987 goto drop;
988
989 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
990 goto drop;
991
992 nh = skb_network_offset(skb);
993 skb_set_network_header(skb, sizeof(*icmph));
994
995 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
996 goto drop;
997
998 skb_set_network_header(skb, nh);
999 }
1000
1001 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1002
1003 if (skb_checksum_simple_validate(skb))
1004 goto csum_error;
1005
1006 if (!pskb_pull(skb, sizeof(*icmph)))
1007 goto error;
1008
1009 icmph = icmp_hdr(skb);
1010
1011 ICMPMSGIN_INC_STATS(net, icmph->type);
1012 /*
1013 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1014 *
1015 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1016 * discarded.
1017 */
1018 if (icmph->type > NR_ICMP_TYPES)
1019 goto error;
1020
1021
1022 /*
1023 * Parse the ICMP message
1024 */
1025
1026 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1027 /*
1028 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1029 * silently ignored (we let user decide with a sysctl).
1030 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1031 * discarded if to broadcast/multicast.
1032 */
1033 if ((icmph->type == ICMP_ECHO ||
1034 icmph->type == ICMP_TIMESTAMP) &&
1035 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1036 goto error;
1037 }
1038 if (icmph->type != ICMP_ECHO &&
1039 icmph->type != ICMP_TIMESTAMP &&
1040 icmph->type != ICMP_ADDRESS &&
1041 icmph->type != ICMP_ADDRESSREPLY) {
1042 goto error;
1043 }
1044 }
1045
1046 success = icmp_pointers[icmph->type].handler(skb);
1047
1048 if (success) {
1049 consume_skb(skb);
1050 return NET_RX_SUCCESS;
1051 }
1052
1053drop:
1054 kfree_skb(skb);
1055 return NET_RX_DROP;
1056csum_error:
1057 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1058error:
1059 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1060 goto drop;
1061}
1062
1063void icmp_err(struct sk_buff *skb, u32 info)
1064{
1065 struct iphdr *iph = (struct iphdr *)skb->data;
1066 int offset = iph->ihl<<2;
1067 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1068 int type = icmp_hdr(skb)->type;
1069 int code = icmp_hdr(skb)->code;
1070 struct net *net = dev_net(skb->dev);
1071
1072 /*
1073 * Use ping_err to handle all icmp errors except those
1074 * triggered by ICMP_ECHOREPLY which sent from kernel.
1075 */
1076 if (icmph->type != ICMP_ECHOREPLY) {
1077 ping_err(skb, offset, info);
1078 return;
1079 }
1080
1081 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1082 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1083 else if (type == ICMP_REDIRECT)
1084 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1085}
1086
1087/*
1088 * This table is the definition of how we handle ICMP.
1089 */
1090static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1091 [ICMP_ECHOREPLY] = {
1092 .handler = ping_rcv,
1093 },
1094 [1] = {
1095 .handler = icmp_discard,
1096 .error = 1,
1097 },
1098 [2] = {
1099 .handler = icmp_discard,
1100 .error = 1,
1101 },
1102 [ICMP_DEST_UNREACH] = {
1103 .handler = icmp_unreach,
1104 .error = 1,
1105 },
1106 [ICMP_SOURCE_QUENCH] = {
1107 .handler = icmp_unreach,
1108 .error = 1,
1109 },
1110 [ICMP_REDIRECT] = {
1111 .handler = icmp_redirect,
1112 .error = 1,
1113 },
1114 [6] = {
1115 .handler = icmp_discard,
1116 .error = 1,
1117 },
1118 [7] = {
1119 .handler = icmp_discard,
1120 .error = 1,
1121 },
1122 [ICMP_ECHO] = {
1123 .handler = icmp_echo,
1124 },
1125 [9] = {
1126 .handler = icmp_discard,
1127 .error = 1,
1128 },
1129 [10] = {
1130 .handler = icmp_discard,
1131 .error = 1,
1132 },
1133 [ICMP_TIME_EXCEEDED] = {
1134 .handler = icmp_unreach,
1135 .error = 1,
1136 },
1137 [ICMP_PARAMETERPROB] = {
1138 .handler = icmp_unreach,
1139 .error = 1,
1140 },
1141 [ICMP_TIMESTAMP] = {
1142 .handler = icmp_timestamp,
1143 },
1144 [ICMP_TIMESTAMPREPLY] = {
1145 .handler = icmp_discard,
1146 },
1147 [ICMP_INFO_REQUEST] = {
1148 .handler = icmp_discard,
1149 },
1150 [ICMP_INFO_REPLY] = {
1151 .handler = icmp_discard,
1152 },
1153 [ICMP_ADDRESS] = {
1154 .handler = icmp_discard,
1155 },
1156 [ICMP_ADDRESSREPLY] = {
1157 .handler = icmp_discard,
1158 },
1159};
1160
1161static void __net_exit icmp_sk_exit(struct net *net)
1162{
1163 int i;
1164
1165 for_each_possible_cpu(i)
1166 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1167 free_percpu(net->ipv4.icmp_sk);
1168 net->ipv4.icmp_sk = NULL;
1169}
1170
1171static int __net_init icmp_sk_init(struct net *net)
1172{
1173 int i, err;
1174
1175 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1176 if (!net->ipv4.icmp_sk)
1177 return -ENOMEM;
1178
1179 for_each_possible_cpu(i) {
1180 struct sock *sk;
1181
1182 err = inet_ctl_sock_create(&sk, PF_INET,
1183 SOCK_RAW, IPPROTO_ICMP, net);
1184 if (err < 0)
1185 goto fail;
1186
1187 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1188
1189 /* Enough space for 2 64K ICMP packets, including
1190 * sk_buff/skb_shared_info struct overhead.
1191 */
1192 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1193
1194 /*
1195 * Speedup sock_wfree()
1196 */
1197 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1198 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1199 }
1200
1201 /* Control parameters for ECHO replies. */
1202 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1203 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1204
1205 /* Control parameter - ignore bogus broadcast responses? */
1206 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1207
1208 /*
1209 * Configurable global rate limit.
1210 *
1211 * ratelimit defines tokens/packet consumed for dst->rate_token
1212 * bucket ratemask defines which icmp types are ratelimited by
1213 * setting it's bit position.
1214 *
1215 * default:
1216 * dest unreachable (3), source quench (4),
1217 * time exceeded (11), parameter problem (12)
1218 */
1219
1220 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1221 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1222 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1223
1224 return 0;
1225
1226fail:
1227 for_each_possible_cpu(i)
1228 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1229 free_percpu(net->ipv4.icmp_sk);
1230 return err;
1231}
1232
1233static struct pernet_operations __net_initdata icmp_sk_ops = {
1234 .init = icmp_sk_init,
1235 .exit = icmp_sk_exit,
1236};
1237
1238int __init icmp_init(void)
1239{
1240 return register_pernet_subsys(&icmp_sk_ops);
1241}