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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 <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
212/* Called with BH disabled */
213static inline struct sock *icmp_xmit_lock(struct net *net)
214{
215 struct sock *sk;
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 return NULL;
224 }
225 return sk;
226}
227
228static inline void icmp_xmit_unlock(struct sock *sk)
229{
230 spin_unlock(&sk->sk_lock.slock);
231}
232
233int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
234int sysctl_icmp_msgs_burst __read_mostly = 50;
235
236static struct {
237 spinlock_t lock;
238 u32 credit;
239 u32 stamp;
240} icmp_global = {
241 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
242};
243
244/**
245 * icmp_global_allow - Are we allowed to send one more ICMP message ?
246 *
247 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
248 * Returns false if we reached the limit and can not send another packet.
249 * Note: called with BH disabled
250 */
251bool icmp_global_allow(void)
252{
253 u32 credit, delta, incr = 0, now = (u32)jiffies;
254 bool rc = false;
255
256 /* Check if token bucket is empty and cannot be refilled
257 * without taking the spinlock.
258 */
259 if (!icmp_global.credit) {
260 delta = min_t(u32, now - icmp_global.stamp, HZ);
261 if (delta < HZ / 50)
262 return false;
263 }
264
265 spin_lock(&icmp_global.lock);
266 delta = min_t(u32, now - icmp_global.stamp, HZ);
267 if (delta >= HZ / 50) {
268 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
269 if (incr)
270 icmp_global.stamp = now;
271 }
272 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
273 if (credit) {
274 credit--;
275 rc = true;
276 }
277 icmp_global.credit = credit;
278 spin_unlock(&icmp_global.lock);
279 return rc;
280}
281EXPORT_SYMBOL(icmp_global_allow);
282
283static bool icmpv4_mask_allow(struct net *net, int type, int code)
284{
285 if (type > NR_ICMP_TYPES)
286 return true;
287
288 /* Don't limit PMTU discovery. */
289 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
290 return true;
291
292 /* Limit if icmp type is enabled in ratemask. */
293 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
294 return true;
295
296 return false;
297}
298
299static bool icmpv4_global_allow(struct net *net, int type, int code)
300{
301 if (icmpv4_mask_allow(net, type, code))
302 return true;
303
304 if (icmp_global_allow())
305 return true;
306
307 return false;
308}
309
310/*
311 * Send an ICMP frame.
312 */
313
314static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
315 struct flowi4 *fl4, int type, int code)
316{
317 struct dst_entry *dst = &rt->dst;
318 struct inet_peer *peer;
319 bool rc = true;
320 int vif;
321
322 if (icmpv4_mask_allow(net, type, code))
323 goto out;
324
325 /* No rate limit on loopback */
326 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
327 goto out;
328
329 vif = l3mdev_master_ifindex(dst->dev);
330 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
331 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
332 if (peer)
333 inet_putpeer(peer);
334out:
335 return rc;
336}
337
338/*
339 * Maintain the counters used in the SNMP statistics for outgoing ICMP
340 */
341void icmp_out_count(struct net *net, unsigned char type)
342{
343 ICMPMSGOUT_INC_STATS(net, type);
344 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
345}
346
347/*
348 * Checksum each fragment, and on the first include the headers and final
349 * checksum.
350 */
351static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
352 struct sk_buff *skb)
353{
354 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
355 __wsum csum;
356
357 csum = skb_copy_and_csum_bits(icmp_param->skb,
358 icmp_param->offset + offset,
359 to, len, 0);
360
361 skb->csum = csum_block_add(skb->csum, csum, odd);
362 if (icmp_pointers[icmp_param->data.icmph.type].error)
363 nf_ct_attach(skb, icmp_param->skb);
364 return 0;
365}
366
367static void icmp_push_reply(struct icmp_bxm *icmp_param,
368 struct flowi4 *fl4,
369 struct ipcm_cookie *ipc, struct rtable **rt)
370{
371 struct sock *sk;
372 struct sk_buff *skb;
373
374 sk = icmp_sk(dev_net((*rt)->dst.dev));
375 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
376 icmp_param->data_len+icmp_param->head_len,
377 icmp_param->head_len,
378 ipc, rt, MSG_DONTWAIT) < 0) {
379 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
380 ip_flush_pending_frames(sk);
381 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
382 struct icmphdr *icmph = icmp_hdr(skb);
383 __wsum csum = 0;
384 struct sk_buff *skb1;
385
386 skb_queue_walk(&sk->sk_write_queue, skb1) {
387 csum = csum_add(csum, skb1->csum);
388 }
389 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
390 (char *)icmph,
391 icmp_param->head_len, csum);
392 icmph->checksum = csum_fold(csum);
393 skb->ip_summed = CHECKSUM_NONE;
394 ip_push_pending_frames(sk, fl4);
395 }
396}
397
398/*
399 * Driving logic for building and sending ICMP messages.
400 */
401
402static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
403{
404 struct ipcm_cookie ipc;
405 struct rtable *rt = skb_rtable(skb);
406 struct net *net = dev_net(rt->dst.dev);
407 struct flowi4 fl4;
408 struct sock *sk;
409 struct inet_sock *inet;
410 __be32 daddr, saddr;
411 u32 mark = IP4_REPLY_MARK(net, skb->mark);
412 int type = icmp_param->data.icmph.type;
413 int code = icmp_param->data.icmph.code;
414
415 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
416 return;
417
418 /* Needed by both icmp_global_allow and icmp_xmit_lock */
419 local_bh_disable();
420
421 /* global icmp_msgs_per_sec */
422 if (!icmpv4_global_allow(net, type, code))
423 goto out_bh_enable;
424
425 sk = icmp_xmit_lock(net);
426 if (!sk)
427 goto out_bh_enable;
428 inet = inet_sk(sk);
429
430 icmp_param->data.icmph.checksum = 0;
431
432 inet->tos = ip_hdr(skb)->tos;
433 sk->sk_mark = mark;
434 daddr = ipc.addr = ip_hdr(skb)->saddr;
435 saddr = fib_compute_spec_dst(skb);
436 ipc.opt = NULL;
437 ipc.tx_flags = 0;
438 ipc.ttl = 0;
439 ipc.tos = -1;
440
441 if (icmp_param->replyopts.opt.opt.optlen) {
442 ipc.opt = &icmp_param->replyopts.opt;
443 if (ipc.opt->opt.srr)
444 daddr = icmp_param->replyopts.opt.opt.faddr;
445 }
446 memset(&fl4, 0, sizeof(fl4));
447 fl4.daddr = daddr;
448 fl4.saddr = saddr;
449 fl4.flowi4_mark = mark;
450 fl4.flowi4_uid = sock_net_uid(net, NULL);
451 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
452 fl4.flowi4_proto = IPPROTO_ICMP;
453 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
454 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
455 rt = ip_route_output_key(net, &fl4);
456 if (IS_ERR(rt))
457 goto out_unlock;
458 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
459 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
460 ip_rt_put(rt);
461out_unlock:
462 icmp_xmit_unlock(sk);
463out_bh_enable:
464 local_bh_enable();
465}
466
467static struct rtable *icmp_route_lookup(struct net *net,
468 struct flowi4 *fl4,
469 struct sk_buff *skb_in,
470 const struct iphdr *iph,
471 __be32 saddr, u8 tos, u32 mark,
472 int type, int code,
473 struct icmp_bxm *param)
474{
475 struct rtable *rt, *rt2;
476 struct flowi4 fl4_dec;
477 int err;
478
479 memset(fl4, 0, sizeof(*fl4));
480 fl4->daddr = (param->replyopts.opt.opt.srr ?
481 param->replyopts.opt.opt.faddr : iph->saddr);
482 fl4->saddr = saddr;
483 fl4->flowi4_mark = mark;
484 fl4->flowi4_uid = sock_net_uid(net, NULL);
485 fl4->flowi4_tos = RT_TOS(tos);
486 fl4->flowi4_proto = IPPROTO_ICMP;
487 fl4->fl4_icmp_type = type;
488 fl4->fl4_icmp_code = code;
489 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev);
490
491 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
492 rt = ip_route_output_key_hash(net, fl4, skb_in);
493 if (IS_ERR(rt))
494 return rt;
495
496 /* No need to clone since we're just using its address. */
497 rt2 = rt;
498
499 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
500 flowi4_to_flowi(fl4), NULL, 0);
501 if (!IS_ERR(rt)) {
502 if (rt != rt2)
503 return rt;
504 } else if (PTR_ERR(rt) == -EPERM) {
505 rt = NULL;
506 } else
507 return rt;
508
509 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
510 if (err)
511 goto relookup_failed;
512
513 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev,
514 fl4_dec.saddr) == RTN_LOCAL) {
515 rt2 = __ip_route_output_key(net, &fl4_dec);
516 if (IS_ERR(rt2))
517 err = PTR_ERR(rt2);
518 } else {
519 struct flowi4 fl4_2 = {};
520 unsigned long orefdst;
521
522 fl4_2.daddr = fl4_dec.saddr;
523 rt2 = ip_route_output_key(net, &fl4_2);
524 if (IS_ERR(rt2)) {
525 err = PTR_ERR(rt2);
526 goto relookup_failed;
527 }
528 /* Ugh! */
529 orefdst = skb_in->_skb_refdst; /* save old refdst */
530 skb_dst_set(skb_in, NULL);
531 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
532 RT_TOS(tos), rt2->dst.dev);
533
534 dst_release(&rt2->dst);
535 rt2 = skb_rtable(skb_in);
536 skb_in->_skb_refdst = orefdst; /* restore old refdst */
537 }
538
539 if (err)
540 goto relookup_failed;
541
542 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
543 flowi4_to_flowi(&fl4_dec), NULL,
544 XFRM_LOOKUP_ICMP);
545 if (!IS_ERR(rt2)) {
546 dst_release(&rt->dst);
547 memcpy(fl4, &fl4_dec, sizeof(*fl4));
548 rt = rt2;
549 } else if (PTR_ERR(rt2) == -EPERM) {
550 if (rt)
551 dst_release(&rt->dst);
552 return rt2;
553 } else {
554 err = PTR_ERR(rt2);
555 goto relookup_failed;
556 }
557 return rt;
558
559relookup_failed:
560 if (rt)
561 return rt;
562 return ERR_PTR(err);
563}
564
565/*
566 * Send an ICMP message in response to a situation
567 *
568 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
569 * MAY send more (we do).
570 * MUST NOT change this header information.
571 * MUST NOT reply to a multicast/broadcast IP address.
572 * MUST NOT reply to a multicast/broadcast MAC address.
573 * MUST reply to only the first fragment.
574 */
575
576void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
577{
578 struct iphdr *iph;
579 int room;
580 struct icmp_bxm icmp_param;
581 struct rtable *rt = skb_rtable(skb_in);
582 struct ipcm_cookie ipc;
583 struct flowi4 fl4;
584 __be32 saddr;
585 u8 tos;
586 u32 mark;
587 struct net *net;
588 struct sock *sk;
589
590 if (!rt)
591 goto out;
592 net = dev_net(rt->dst.dev);
593
594 /*
595 * Find the original header. It is expected to be valid, of course.
596 * Check this, icmp_send is called from the most obscure devices
597 * sometimes.
598 */
599 iph = ip_hdr(skb_in);
600
601 if ((u8 *)iph < skb_in->head ||
602 (skb_network_header(skb_in) + sizeof(*iph)) >
603 skb_tail_pointer(skb_in))
604 goto out;
605
606 /*
607 * No replies to physical multicast/broadcast
608 */
609 if (skb_in->pkt_type != PACKET_HOST)
610 goto out;
611
612 /*
613 * Now check at the protocol level
614 */
615 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
616 goto out;
617
618 /*
619 * Only reply to fragment 0. We byte re-order the constant
620 * mask for efficiency.
621 */
622 if (iph->frag_off & htons(IP_OFFSET))
623 goto out;
624
625 /*
626 * If we send an ICMP error to an ICMP error a mess would result..
627 */
628 if (icmp_pointers[type].error) {
629 /*
630 * We are an error, check if we are replying to an
631 * ICMP error
632 */
633 if (iph->protocol == IPPROTO_ICMP) {
634 u8 _inner_type, *itp;
635
636 itp = skb_header_pointer(skb_in,
637 skb_network_header(skb_in) +
638 (iph->ihl << 2) +
639 offsetof(struct icmphdr,
640 type) -
641 skb_in->data,
642 sizeof(_inner_type),
643 &_inner_type);
644 if (!itp)
645 goto out;
646
647 /*
648 * Assume any unknown ICMP type is an error. This
649 * isn't specified by the RFC, but think about it..
650 */
651 if (*itp > NR_ICMP_TYPES ||
652 icmp_pointers[*itp].error)
653 goto out;
654 }
655 }
656
657 /* Needed by both icmp_global_allow and icmp_xmit_lock */
658 local_bh_disable();
659
660 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
661 * incoming dev is loopback. If outgoing dev change to not be
662 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
663 */
664 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
665 !icmpv4_global_allow(net, type, code))
666 goto out_bh_enable;
667
668 sk = icmp_xmit_lock(net);
669 if (!sk)
670 goto out_bh_enable;
671
672 /*
673 * Construct source address and options.
674 */
675
676 saddr = iph->daddr;
677 if (!(rt->rt_flags & RTCF_LOCAL)) {
678 struct net_device *dev = NULL;
679
680 rcu_read_lock();
681 if (rt_is_input_route(rt) &&
682 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
683 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
684
685 if (dev)
686 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
687 else
688 saddr = 0;
689 rcu_read_unlock();
690 }
691
692 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
693 IPTOS_PREC_INTERNETCONTROL) :
694 iph->tos;
695 mark = IP4_REPLY_MARK(net, skb_in->mark);
696
697 if (ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in))
698 goto out_unlock;
699
700
701 /*
702 * Prepare data for ICMP header.
703 */
704
705 icmp_param.data.icmph.type = type;
706 icmp_param.data.icmph.code = code;
707 icmp_param.data.icmph.un.gateway = info;
708 icmp_param.data.icmph.checksum = 0;
709 icmp_param.skb = skb_in;
710 icmp_param.offset = skb_network_offset(skb_in);
711 inet_sk(sk)->tos = tos;
712 sk->sk_mark = mark;
713 ipc.addr = iph->saddr;
714 ipc.opt = &icmp_param.replyopts.opt;
715 ipc.tx_flags = 0;
716 ipc.ttl = 0;
717 ipc.tos = -1;
718
719 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
720 type, code, &icmp_param);
721 if (IS_ERR(rt))
722 goto out_unlock;
723
724 /* peer icmp_ratelimit */
725 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
726 goto ende;
727
728 /* RFC says return as much as we can without exceeding 576 bytes. */
729
730 room = dst_mtu(&rt->dst);
731 if (room > 576)
732 room = 576;
733 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
734 room -= sizeof(struct icmphdr);
735
736 icmp_param.data_len = skb_in->len - icmp_param.offset;
737 if (icmp_param.data_len > room)
738 icmp_param.data_len = room;
739 icmp_param.head_len = sizeof(struct icmphdr);
740
741 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
742ende:
743 ip_rt_put(rt);
744out_unlock:
745 icmp_xmit_unlock(sk);
746out_bh_enable:
747 local_bh_enable();
748out:;
749}
750EXPORT_SYMBOL(icmp_send);
751
752
753static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
754{
755 const struct iphdr *iph = (const struct iphdr *) skb->data;
756 const struct net_protocol *ipprot;
757 int protocol = iph->protocol;
758
759 /* Checkin full IP header plus 8 bytes of protocol to
760 * avoid additional coding at protocol handlers.
761 */
762 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
763 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
764 return;
765 }
766
767 raw_icmp_error(skb, protocol, info);
768
769 ipprot = rcu_dereference(inet_protos[protocol]);
770 if (ipprot && ipprot->err_handler)
771 ipprot->err_handler(skb, info);
772}
773
774static bool icmp_tag_validation(int proto)
775{
776 bool ok;
777
778 rcu_read_lock();
779 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
780 rcu_read_unlock();
781 return ok;
782}
783
784/*
785 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
786 * ICMP_PARAMETERPROB.
787 */
788
789static bool icmp_unreach(struct sk_buff *skb)
790{
791 const struct iphdr *iph;
792 struct icmphdr *icmph;
793 struct net *net;
794 u32 info = 0;
795
796 net = dev_net(skb_dst(skb)->dev);
797
798 /*
799 * Incomplete header ?
800 * Only checks for the IP header, there should be an
801 * additional check for longer headers in upper levels.
802 */
803
804 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
805 goto out_err;
806
807 icmph = icmp_hdr(skb);
808 iph = (const struct iphdr *)skb->data;
809
810 if (iph->ihl < 5) /* Mangled header, drop. */
811 goto out_err;
812
813 switch (icmph->type) {
814 case ICMP_DEST_UNREACH:
815 switch (icmph->code & 15) {
816 case ICMP_NET_UNREACH:
817 case ICMP_HOST_UNREACH:
818 case ICMP_PROT_UNREACH:
819 case ICMP_PORT_UNREACH:
820 break;
821 case ICMP_FRAG_NEEDED:
822 /* for documentation of the ip_no_pmtu_disc
823 * values please see
824 * Documentation/networking/ip-sysctl.txt
825 */
826 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
827 default:
828 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
829 &iph->daddr);
830 break;
831 case 2:
832 goto out;
833 case 3:
834 if (!icmp_tag_validation(iph->protocol))
835 goto out;
836 /* fall through */
837 case 0:
838 info = ntohs(icmph->un.frag.mtu);
839 }
840 break;
841 case ICMP_SR_FAILED:
842 net_dbg_ratelimited("%pI4: Source Route Failed\n",
843 &iph->daddr);
844 break;
845 default:
846 break;
847 }
848 if (icmph->code > NR_ICMP_UNREACH)
849 goto out;
850 break;
851 case ICMP_PARAMETERPROB:
852 info = ntohl(icmph->un.gateway) >> 24;
853 break;
854 case ICMP_TIME_EXCEEDED:
855 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
856 if (icmph->code == ICMP_EXC_FRAGTIME)
857 goto out;
858 break;
859 }
860
861 /*
862 * Throw it at our lower layers
863 *
864 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
865 * header.
866 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
867 * transport layer.
868 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
869 * transport layer.
870 */
871
872 /*
873 * Check the other end isn't violating RFC 1122. Some routers send
874 * bogus responses to broadcast frames. If you see this message
875 * first check your netmask matches at both ends, if it does then
876 * get the other vendor to fix their kit.
877 */
878
879 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
880 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
881 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
882 &ip_hdr(skb)->saddr,
883 icmph->type, icmph->code,
884 &iph->daddr, skb->dev->name);
885 goto out;
886 }
887
888 icmp_socket_deliver(skb, info);
889
890out:
891 return true;
892out_err:
893 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
894 return false;
895}
896
897
898/*
899 * Handle ICMP_REDIRECT.
900 */
901
902static bool icmp_redirect(struct sk_buff *skb)
903{
904 if (skb->len < sizeof(struct iphdr)) {
905 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
906 return false;
907 }
908
909 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
910 /* there aught to be a stat */
911 return false;
912 }
913
914 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
915 return true;
916}
917
918/*
919 * Handle ICMP_ECHO ("ping") requests.
920 *
921 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
922 * requests.
923 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
924 * included in the reply.
925 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
926 * echo requests, MUST have default=NOT.
927 * See also WRT handling of options once they are done and working.
928 */
929
930static bool icmp_echo(struct sk_buff *skb)
931{
932 struct net *net;
933
934 net = dev_net(skb_dst(skb)->dev);
935 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
936 struct icmp_bxm icmp_param;
937
938 icmp_param.data.icmph = *icmp_hdr(skb);
939 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
940 icmp_param.skb = skb;
941 icmp_param.offset = 0;
942 icmp_param.data_len = skb->len;
943 icmp_param.head_len = sizeof(struct icmphdr);
944 icmp_reply(&icmp_param, skb);
945 }
946 /* should there be an ICMP stat for ignored echos? */
947 return true;
948}
949
950/*
951 * Handle ICMP Timestamp requests.
952 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
953 * SHOULD be in the kernel for minimum random latency.
954 * MUST be accurate to a few minutes.
955 * MUST be updated at least at 15Hz.
956 */
957static bool icmp_timestamp(struct sk_buff *skb)
958{
959 struct icmp_bxm icmp_param;
960 /*
961 * Too short.
962 */
963 if (skb->len < 4)
964 goto out_err;
965
966 /*
967 * Fill in the current time as ms since midnight UT:
968 */
969 icmp_param.data.times[1] = inet_current_timestamp();
970 icmp_param.data.times[2] = icmp_param.data.times[1];
971
972 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
973
974 icmp_param.data.icmph = *icmp_hdr(skb);
975 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
976 icmp_param.data.icmph.code = 0;
977 icmp_param.skb = skb;
978 icmp_param.offset = 0;
979 icmp_param.data_len = 0;
980 icmp_param.head_len = sizeof(struct icmphdr) + 12;
981 icmp_reply(&icmp_param, skb);
982 return true;
983
984out_err:
985 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
986 return false;
987}
988
989static bool icmp_discard(struct sk_buff *skb)
990{
991 /* pretend it was a success */
992 return true;
993}
994
995/*
996 * Deal with incoming ICMP packets.
997 */
998int icmp_rcv(struct sk_buff *skb)
999{
1000 struct icmphdr *icmph;
1001 struct rtable *rt = skb_rtable(skb);
1002 struct net *net = dev_net(rt->dst.dev);
1003 bool success;
1004
1005 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1006 struct sec_path *sp = skb_sec_path(skb);
1007 int nh;
1008
1009 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1010 XFRM_STATE_ICMP))
1011 goto drop;
1012
1013 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1014 goto drop;
1015
1016 nh = skb_network_offset(skb);
1017 skb_set_network_header(skb, sizeof(*icmph));
1018
1019 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1020 goto drop;
1021
1022 skb_set_network_header(skb, nh);
1023 }
1024
1025 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1026
1027 if (skb_checksum_simple_validate(skb))
1028 goto csum_error;
1029
1030 if (!pskb_pull(skb, sizeof(*icmph)))
1031 goto error;
1032
1033 icmph = icmp_hdr(skb);
1034
1035 ICMPMSGIN_INC_STATS(net, icmph->type);
1036 /*
1037 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1038 *
1039 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1040 * discarded.
1041 */
1042 if (icmph->type > NR_ICMP_TYPES)
1043 goto error;
1044
1045
1046 /*
1047 * Parse the ICMP message
1048 */
1049
1050 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1051 /*
1052 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1053 * silently ignored (we let user decide with a sysctl).
1054 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1055 * discarded if to broadcast/multicast.
1056 */
1057 if ((icmph->type == ICMP_ECHO ||
1058 icmph->type == ICMP_TIMESTAMP) &&
1059 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1060 goto error;
1061 }
1062 if (icmph->type != ICMP_ECHO &&
1063 icmph->type != ICMP_TIMESTAMP &&
1064 icmph->type != ICMP_ADDRESS &&
1065 icmph->type != ICMP_ADDRESSREPLY) {
1066 goto error;
1067 }
1068 }
1069
1070 success = icmp_pointers[icmph->type].handler(skb);
1071
1072 if (success) {
1073 consume_skb(skb);
1074 return NET_RX_SUCCESS;
1075 }
1076
1077drop:
1078 kfree_skb(skb);
1079 return NET_RX_DROP;
1080csum_error:
1081 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1082error:
1083 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1084 goto drop;
1085}
1086
1087void icmp_err(struct sk_buff *skb, u32 info)
1088{
1089 struct iphdr *iph = (struct iphdr *)skb->data;
1090 int offset = iph->ihl<<2;
1091 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1092 int type = icmp_hdr(skb)->type;
1093 int code = icmp_hdr(skb)->code;
1094 struct net *net = dev_net(skb->dev);
1095
1096 /*
1097 * Use ping_err to handle all icmp errors except those
1098 * triggered by ICMP_ECHOREPLY which sent from kernel.
1099 */
1100 if (icmph->type != ICMP_ECHOREPLY) {
1101 ping_err(skb, offset, info);
1102 return;
1103 }
1104
1105 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1106 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1107 else if (type == ICMP_REDIRECT)
1108 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1109}
1110
1111/*
1112 * This table is the definition of how we handle ICMP.
1113 */
1114static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1115 [ICMP_ECHOREPLY] = {
1116 .handler = ping_rcv,
1117 },
1118 [1] = {
1119 .handler = icmp_discard,
1120 .error = 1,
1121 },
1122 [2] = {
1123 .handler = icmp_discard,
1124 .error = 1,
1125 },
1126 [ICMP_DEST_UNREACH] = {
1127 .handler = icmp_unreach,
1128 .error = 1,
1129 },
1130 [ICMP_SOURCE_QUENCH] = {
1131 .handler = icmp_unreach,
1132 .error = 1,
1133 },
1134 [ICMP_REDIRECT] = {
1135 .handler = icmp_redirect,
1136 .error = 1,
1137 },
1138 [6] = {
1139 .handler = icmp_discard,
1140 .error = 1,
1141 },
1142 [7] = {
1143 .handler = icmp_discard,
1144 .error = 1,
1145 },
1146 [ICMP_ECHO] = {
1147 .handler = icmp_echo,
1148 },
1149 [9] = {
1150 .handler = icmp_discard,
1151 .error = 1,
1152 },
1153 [10] = {
1154 .handler = icmp_discard,
1155 .error = 1,
1156 },
1157 [ICMP_TIME_EXCEEDED] = {
1158 .handler = icmp_unreach,
1159 .error = 1,
1160 },
1161 [ICMP_PARAMETERPROB] = {
1162 .handler = icmp_unreach,
1163 .error = 1,
1164 },
1165 [ICMP_TIMESTAMP] = {
1166 .handler = icmp_timestamp,
1167 },
1168 [ICMP_TIMESTAMPREPLY] = {
1169 .handler = icmp_discard,
1170 },
1171 [ICMP_INFO_REQUEST] = {
1172 .handler = icmp_discard,
1173 },
1174 [ICMP_INFO_REPLY] = {
1175 .handler = icmp_discard,
1176 },
1177 [ICMP_ADDRESS] = {
1178 .handler = icmp_discard,
1179 },
1180 [ICMP_ADDRESSREPLY] = {
1181 .handler = icmp_discard,
1182 },
1183};
1184
1185static void __net_exit icmp_sk_exit(struct net *net)
1186{
1187 int i;
1188
1189 for_each_possible_cpu(i)
1190 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1191 free_percpu(net->ipv4.icmp_sk);
1192 net->ipv4.icmp_sk = NULL;
1193}
1194
1195static int __net_init icmp_sk_init(struct net *net)
1196{
1197 int i, err;
1198
1199 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1200 if (!net->ipv4.icmp_sk)
1201 return -ENOMEM;
1202
1203 for_each_possible_cpu(i) {
1204 struct sock *sk;
1205
1206 err = inet_ctl_sock_create(&sk, PF_INET,
1207 SOCK_RAW, IPPROTO_ICMP, net);
1208 if (err < 0)
1209 goto fail;
1210
1211 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1212
1213 /* Enough space for 2 64K ICMP packets, including
1214 * sk_buff/skb_shared_info struct overhead.
1215 */
1216 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1217
1218 /*
1219 * Speedup sock_wfree()
1220 */
1221 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1222 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1223 }
1224
1225 /* Control parameters for ECHO replies. */
1226 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1227 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1228
1229 /* Control parameter - ignore bogus broadcast responses? */
1230 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1231
1232 /*
1233 * Configurable global rate limit.
1234 *
1235 * ratelimit defines tokens/packet consumed for dst->rate_token
1236 * bucket ratemask defines which icmp types are ratelimited by
1237 * setting it's bit position.
1238 *
1239 * default:
1240 * dest unreachable (3), source quench (4),
1241 * time exceeded (11), parameter problem (12)
1242 */
1243
1244 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1245 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1246 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1247
1248 return 0;
1249
1250fail:
1251 for_each_possible_cpu(i)
1252 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1253 free_percpu(net->ipv4.icmp_sk);
1254 return err;
1255}
1256
1257static struct pernet_operations __net_initdata icmp_sk_ops = {
1258 .init = icmp_sk_init,
1259 .exit = icmp_sk_exit,
1260};
1261
1262int __init icmp_init(void)
1263{
1264 return register_pernet_subsys(&icmp_sk_ops);
1265}