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