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