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