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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * NET3: Implementation of the ICMP protocol layer.
4 *
5 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
6 *
7 * Some of the function names and the icmp unreach table for this
8 * module were derived from [icmp.c 1.0.11 06/02/93] by
9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
10 * Other than that this module is a complete rewrite.
11 *
12 * Fixes:
13 * Clemens Fruhwirth : introduce global icmp rate limiting
14 * with icmp type masking ability instead
15 * of broken per type icmp timeouts.
16 * Mike Shaver : RFC1122 checks.
17 * Alan Cox : Multicast ping reply as self.
18 * Alan Cox : Fix atomicity lockup in ip_build_xmit
19 * call.
20 * Alan Cox : Added 216,128 byte paths to the MTU
21 * code.
22 * Martin Mares : RFC1812 checks.
23 * Martin Mares : Can be configured to follow redirects
24 * if acting as a router _without_ a
25 * routing protocol (RFC 1812).
26 * Martin Mares : Echo requests may be configured to
27 * be ignored (RFC 1812).
28 * Martin Mares : Limitation of ICMP error message
29 * transmit rate (RFC 1812).
30 * Martin Mares : TOS and Precedence set correctly
31 * (RFC 1812).
32 * Martin Mares : Now copying as much data from the
33 * original packet as we can without
34 * exceeding 576 bytes (RFC 1812).
35 * Willy Konynenberg : Transparent proxying support.
36 * Keith Owens : RFC1191 correction for 4.2BSD based
37 * path MTU bug.
38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
39 * valid (RFC 1812).
40 * Andi Kleen : Check all packet lengths properly
41 * and moved all kfree_skb() up to
42 * icmp_rcv.
43 * Andi Kleen : Move the rate limit bookkeeping
44 * into the dest entry and use a token
45 * bucket filter (thanks to ANK). Make
46 * the rates sysctl configurable.
47 * Yu Tianli : Fixed two ugly bugs in icmp_send
48 * - IP option length was accounted wrongly
49 * - ICMP header length was not accounted
50 * at all.
51 * Tristan Greaves : Added sysctl option to ignore bogus
52 * broadcast responses from broken routers.
53 *
54 * To Fix:
55 *
56 * - Should use skb_pull() instead of all the manual checking.
57 * This would also greatly simply some upper layer error handlers. --AK
58 */
59
60#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61
62#include <linux/module.h>
63#include <linux/types.h>
64#include <linux/jiffies.h>
65#include <linux/kernel.h>
66#include <linux/fcntl.h>
67#include <linux/socket.h>
68#include <linux/in.h>
69#include <linux/inet.h>
70#include <linux/inetdevice.h>
71#include <linux/netdevice.h>
72#include <linux/string.h>
73#include <linux/netfilter_ipv4.h>
74#include <linux/slab.h>
75#include <net/snmp.h>
76#include <net/ip.h>
77#include <net/route.h>
78#include <net/protocol.h>
79#include <net/icmp.h>
80#include <net/tcp.h>
81#include <net/udp.h>
82#include <net/raw.h>
83#include <net/ping.h>
84#include <linux/skbuff.h>
85#include <net/sock.h>
86#include <linux/errno.h>
87#include <linux/timer.h>
88#include <linux/init.h>
89#include <linux/uaccess.h>
90#include <net/checksum.h>
91#include <net/xfrm.h>
92#include <net/inet_common.h>
93#include <net/ip_fib.h>
94#include <net/l3mdev.h>
95
96/*
97 * Build xmit assembly blocks
98 */
99
100struct icmp_bxm {
101 struct sk_buff *skb;
102 int offset;
103 int data_len;
104
105 struct {
106 struct icmphdr icmph;
107 __be32 times[3];
108 } data;
109 int head_len;
110 struct ip_options_data replyopts;
111};
112
113/* An array of errno for error messages from dest unreach. */
114/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
115
116const struct icmp_err icmp_err_convert[] = {
117 {
118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
119 .fatal = 0,
120 },
121 {
122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
123 .fatal = 0,
124 },
125 {
126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
127 .fatal = 1,
128 },
129 {
130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
131 .fatal = 1,
132 },
133 {
134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
135 .fatal = 0,
136 },
137 {
138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
139 .fatal = 0,
140 },
141 {
142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
143 .fatal = 1,
144 },
145 {
146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
147 .fatal = 1,
148 },
149 {
150 .errno = ENONET, /* ICMP_HOST_ISOLATED */
151 .fatal = 1,
152 },
153 {
154 .errno = ENETUNREACH, /* ICMP_NET_ANO */
155 .fatal = 1,
156 },
157 {
158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
159 .fatal = 1,
160 },
161 {
162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
163 .fatal = 0,
164 },
165 {
166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
167 .fatal = 0,
168 },
169 {
170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
171 .fatal = 1,
172 },
173 {
174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
175 .fatal = 1,
176 },
177 {
178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
179 .fatal = 1,
180 },
181};
182EXPORT_SYMBOL(icmp_err_convert);
183
184/*
185 * ICMP control array. This specifies what to do with each ICMP.
186 */
187
188struct icmp_control {
189 bool (*handler)(struct sk_buff *skb);
190 short error; /* This ICMP is classed as an error message */
191};
192
193static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
194
195/*
196 * The ICMP socket(s). This is the most convenient way to flow control
197 * our ICMP output as well as maintain a clean interface throughout
198 * all layers. All Socketless IP sends will soon be gone.
199 *
200 * On SMP we have one ICMP socket per-cpu.
201 */
202static struct sock *icmp_sk(struct net *net)
203{
204 return this_cpu_read(*net->ipv4.icmp_sk);
205}
206
207/* Called with BH disabled */
208static inline struct sock *icmp_xmit_lock(struct net *net)
209{
210 struct sock *sk;
211
212 sk = icmp_sk(net);
213
214 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
215 /* This can happen if the output path signals a
216 * dst_link_failure() for an outgoing ICMP packet.
217 */
218 return NULL;
219 }
220 return sk;
221}
222
223static inline void icmp_xmit_unlock(struct sock *sk)
224{
225 spin_unlock(&sk->sk_lock.slock);
226}
227
228int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
229int sysctl_icmp_msgs_burst __read_mostly = 50;
230
231static struct {
232 spinlock_t lock;
233 u32 credit;
234 u32 stamp;
235} icmp_global = {
236 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
237};
238
239/**
240 * icmp_global_allow - Are we allowed to send one more ICMP message ?
241 *
242 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
243 * Returns false if we reached the limit and can not send another packet.
244 * Note: called with BH disabled
245 */
246bool icmp_global_allow(void)
247{
248 u32 credit, delta, incr = 0, now = (u32)jiffies;
249 bool rc = false;
250
251 /* Check if token bucket is empty and cannot be refilled
252 * without taking the spinlock. The READ_ONCE() are paired
253 * with the following WRITE_ONCE() in this same function.
254 */
255 if (!READ_ONCE(icmp_global.credit)) {
256 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
257 if (delta < HZ / 50)
258 return false;
259 }
260
261 spin_lock(&icmp_global.lock);
262 delta = min_t(u32, now - icmp_global.stamp, HZ);
263 if (delta >= HZ / 50) {
264 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
265 if (incr)
266 WRITE_ONCE(icmp_global.stamp, now);
267 }
268 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
269 if (credit) {
270 credit--;
271 rc = true;
272 }
273 WRITE_ONCE(icmp_global.credit, credit);
274 spin_unlock(&icmp_global.lock);
275 return rc;
276}
277EXPORT_SYMBOL(icmp_global_allow);
278
279static bool icmpv4_mask_allow(struct net *net, int type, int code)
280{
281 if (type > NR_ICMP_TYPES)
282 return true;
283
284 /* Don't limit PMTU discovery. */
285 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
286 return true;
287
288 /* Limit if icmp type is enabled in ratemask. */
289 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
290 return true;
291
292 return false;
293}
294
295static bool icmpv4_global_allow(struct net *net, int type, int code)
296{
297 if (icmpv4_mask_allow(net, type, code))
298 return true;
299
300 if (icmp_global_allow())
301 return true;
302
303 return false;
304}
305
306/*
307 * Send an ICMP frame.
308 */
309
310static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
311 struct flowi4 *fl4, int type, int code)
312{
313 struct dst_entry *dst = &rt->dst;
314 struct inet_peer *peer;
315 bool rc = true;
316 int vif;
317
318 if (icmpv4_mask_allow(net, type, code))
319 goto out;
320
321 /* No rate limit on loopback */
322 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
323 goto out;
324
325 vif = l3mdev_master_ifindex(dst->dev);
326 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
327 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
328 if (peer)
329 inet_putpeer(peer);
330out:
331 return rc;
332}
333
334/*
335 * Maintain the counters used in the SNMP statistics for outgoing ICMP
336 */
337void icmp_out_count(struct net *net, unsigned char type)
338{
339 ICMPMSGOUT_INC_STATS(net, type);
340 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
341}
342
343/*
344 * Checksum each fragment, and on the first include the headers and final
345 * checksum.
346 */
347static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
348 struct sk_buff *skb)
349{
350 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
351 __wsum csum;
352
353 csum = skb_copy_and_csum_bits(icmp_param->skb,
354 icmp_param->offset + offset,
355 to, len, 0);
356
357 skb->csum = csum_block_add(skb->csum, csum, odd);
358 if (icmp_pointers[icmp_param->data.icmph.type].error)
359 nf_ct_attach(skb, icmp_param->skb);
360 return 0;
361}
362
363static void icmp_push_reply(struct icmp_bxm *icmp_param,
364 struct flowi4 *fl4,
365 struct ipcm_cookie *ipc, struct rtable **rt)
366{
367 struct sock *sk;
368 struct sk_buff *skb;
369
370 sk = icmp_sk(dev_net((*rt)->dst.dev));
371 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
372 icmp_param->data_len+icmp_param->head_len,
373 icmp_param->head_len,
374 ipc, rt, MSG_DONTWAIT) < 0) {
375 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
376 ip_flush_pending_frames(sk);
377 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
378 struct icmphdr *icmph = icmp_hdr(skb);
379 __wsum csum = 0;
380 struct sk_buff *skb1;
381
382 skb_queue_walk(&sk->sk_write_queue, skb1) {
383 csum = csum_add(csum, skb1->csum);
384 }
385 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
386 (char *)icmph,
387 icmp_param->head_len, csum);
388 icmph->checksum = csum_fold(csum);
389 skb->ip_summed = CHECKSUM_NONE;
390 ip_push_pending_frames(sk, fl4);
391 }
392}
393
394/*
395 * Driving logic for building and sending ICMP messages.
396 */
397
398static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
399{
400 struct ipcm_cookie ipc;
401 struct rtable *rt = skb_rtable(skb);
402 struct net *net = dev_net(rt->dst.dev);
403 struct flowi4 fl4;
404 struct sock *sk;
405 struct inet_sock *inet;
406 __be32 daddr, saddr;
407 u32 mark = IP4_REPLY_MARK(net, skb->mark);
408 int type = icmp_param->data.icmph.type;
409 int code = icmp_param->data.icmph.code;
410
411 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
412 return;
413
414 /* Needed by both icmp_global_allow and icmp_xmit_lock */
415 local_bh_disable();
416
417 /* global icmp_msgs_per_sec */
418 if (!icmpv4_global_allow(net, type, code))
419 goto out_bh_enable;
420
421 sk = icmp_xmit_lock(net);
422 if (!sk)
423 goto out_bh_enable;
424 inet = inet_sk(sk);
425
426 icmp_param->data.icmph.checksum = 0;
427
428 ipcm_init(&ipc);
429 inet->tos = ip_hdr(skb)->tos;
430 ipc.sockc.mark = mark;
431 daddr = ipc.addr = ip_hdr(skb)->saddr;
432 saddr = fib_compute_spec_dst(skb);
433
434 if (icmp_param->replyopts.opt.opt.optlen) {
435 ipc.opt = &icmp_param->replyopts.opt;
436 if (ipc.opt->opt.srr)
437 daddr = icmp_param->replyopts.opt.opt.faddr;
438 }
439 memset(&fl4, 0, sizeof(fl4));
440 fl4.daddr = daddr;
441 fl4.saddr = saddr;
442 fl4.flowi4_mark = mark;
443 fl4.flowi4_uid = sock_net_uid(net, NULL);
444 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
445 fl4.flowi4_proto = IPPROTO_ICMP;
446 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
447 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
448 rt = ip_route_output_key(net, &fl4);
449 if (IS_ERR(rt))
450 goto out_unlock;
451 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
452 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
453 ip_rt_put(rt);
454out_unlock:
455 icmp_xmit_unlock(sk);
456out_bh_enable:
457 local_bh_enable();
458}
459
460static struct rtable *icmp_route_lookup(struct net *net,
461 struct flowi4 *fl4,
462 struct sk_buff *skb_in,
463 const struct iphdr *iph,
464 __be32 saddr, u8 tos, u32 mark,
465 int type, int code,
466 struct icmp_bxm *param)
467{
468 struct rtable *rt, *rt2;
469 struct flowi4 fl4_dec;
470 int err;
471
472 memset(fl4, 0, sizeof(*fl4));
473 fl4->daddr = (param->replyopts.opt.opt.srr ?
474 param->replyopts.opt.opt.faddr : iph->saddr);
475 fl4->saddr = saddr;
476 fl4->flowi4_mark = mark;
477 fl4->flowi4_uid = sock_net_uid(net, NULL);
478 fl4->flowi4_tos = RT_TOS(tos);
479 fl4->flowi4_proto = IPPROTO_ICMP;
480 fl4->fl4_icmp_type = type;
481 fl4->fl4_icmp_code = code;
482 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev);
483
484 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
485 rt = ip_route_output_key_hash(net, fl4, skb_in);
486 if (IS_ERR(rt))
487 return rt;
488
489 /* No need to clone since we're just using its address. */
490 rt2 = rt;
491
492 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
493 flowi4_to_flowi(fl4), NULL, 0);
494 if (!IS_ERR(rt)) {
495 if (rt != rt2)
496 return rt;
497 } else if (PTR_ERR(rt) == -EPERM) {
498 rt = NULL;
499 } else
500 return rt;
501
502 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
503 if (err)
504 goto relookup_failed;
505
506 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev,
507 fl4_dec.saddr) == RTN_LOCAL) {
508 rt2 = __ip_route_output_key(net, &fl4_dec);
509 if (IS_ERR(rt2))
510 err = PTR_ERR(rt2);
511 } else {
512 struct flowi4 fl4_2 = {};
513 unsigned long orefdst;
514
515 fl4_2.daddr = fl4_dec.saddr;
516 rt2 = ip_route_output_key(net, &fl4_2);
517 if (IS_ERR(rt2)) {
518 err = PTR_ERR(rt2);
519 goto relookup_failed;
520 }
521 /* Ugh! */
522 orefdst = skb_in->_skb_refdst; /* save old refdst */
523 skb_dst_set(skb_in, NULL);
524 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
525 RT_TOS(tos), rt2->dst.dev);
526
527 dst_release(&rt2->dst);
528 rt2 = skb_rtable(skb_in);
529 skb_in->_skb_refdst = orefdst; /* restore old refdst */
530 }
531
532 if (err)
533 goto relookup_failed;
534
535 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
536 flowi4_to_flowi(&fl4_dec), NULL,
537 XFRM_LOOKUP_ICMP);
538 if (!IS_ERR(rt2)) {
539 dst_release(&rt->dst);
540 memcpy(fl4, &fl4_dec, sizeof(*fl4));
541 rt = rt2;
542 } else if (PTR_ERR(rt2) == -EPERM) {
543 if (rt)
544 dst_release(&rt->dst);
545 return rt2;
546 } else {
547 err = PTR_ERR(rt2);
548 goto relookup_failed;
549 }
550 return rt;
551
552relookup_failed:
553 if (rt)
554 return rt;
555 return ERR_PTR(err);
556}
557
558/*
559 * Send an ICMP message in response to a situation
560 *
561 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
562 * MAY send more (we do).
563 * MUST NOT change this header information.
564 * MUST NOT reply to a multicast/broadcast IP address.
565 * MUST NOT reply to a multicast/broadcast MAC address.
566 * MUST reply to only the first fragment.
567 */
568
569void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
570 const struct ip_options *opt)
571{
572 struct iphdr *iph;
573 int room;
574 struct icmp_bxm icmp_param;
575 struct rtable *rt = skb_rtable(skb_in);
576 struct ipcm_cookie ipc;
577 struct flowi4 fl4;
578 __be32 saddr;
579 u8 tos;
580 u32 mark;
581 struct net *net;
582 struct sock *sk;
583
584 if (!rt)
585 goto out;
586
587 if (rt->dst.dev)
588 net = dev_net(rt->dst.dev);
589 else if (skb_in->dev)
590 net = dev_net(skb_in->dev);
591 else
592 goto out;
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, iph->saddr,
687 RT_SCOPE_LINK);
688 else
689 saddr = 0;
690 rcu_read_unlock();
691 }
692
693 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
694 IPTOS_PREC_INTERNETCONTROL) :
695 iph->tos;
696 mark = IP4_REPLY_MARK(net, skb_in->mark);
697
698 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
699 goto out_unlock;
700
701
702 /*
703 * Prepare data for ICMP header.
704 */
705
706 icmp_param.data.icmph.type = type;
707 icmp_param.data.icmph.code = code;
708 icmp_param.data.icmph.un.gateway = info;
709 icmp_param.data.icmph.checksum = 0;
710 icmp_param.skb = skb_in;
711 icmp_param.offset = skb_network_offset(skb_in);
712 inet_sk(sk)->tos = tos;
713 ipcm_init(&ipc);
714 ipc.addr = iph->saddr;
715 ipc.opt = &icmp_param.replyopts.opt;
716 ipc.sockc.mark = mark;
717
718 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
719 type, code, &icmp_param);
720 if (IS_ERR(rt))
721 goto out_unlock;
722
723 /* peer icmp_ratelimit */
724 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
725 goto ende;
726
727 /* RFC says return as much as we can without exceeding 576 bytes. */
728
729 room = dst_mtu(&rt->dst);
730 if (room > 576)
731 room = 576;
732 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
733 room -= sizeof(struct icmphdr);
734
735 icmp_param.data_len = skb_in->len - icmp_param.offset;
736 if (icmp_param.data_len > room)
737 icmp_param.data_len = room;
738 icmp_param.head_len = sizeof(struct icmphdr);
739
740 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
741ende:
742 ip_rt_put(rt);
743out_unlock:
744 icmp_xmit_unlock(sk);
745out_bh_enable:
746 local_bh_enable();
747out:;
748}
749EXPORT_SYMBOL(__icmp_send);
750
751#if IS_ENABLED(CONFIG_NF_NAT)
752#include <net/netfilter/nf_conntrack.h>
753void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
754{
755 struct sk_buff *cloned_skb = NULL;
756 enum ip_conntrack_info ctinfo;
757 struct nf_conn *ct;
758 __be32 orig_ip;
759
760 ct = nf_ct_get(skb_in, &ctinfo);
761 if (!ct || !(ct->status & IPS_SRC_NAT)) {
762 icmp_send(skb_in, type, code, info);
763 return;
764 }
765
766 if (skb_shared(skb_in))
767 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
768
769 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
770 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
771 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
772 skb_network_offset(skb_in) + sizeof(struct iphdr))))
773 goto out;
774
775 orig_ip = ip_hdr(skb_in)->saddr;
776 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
777 icmp_send(skb_in, type, code, info);
778 ip_hdr(skb_in)->saddr = orig_ip;
779out:
780 consume_skb(cloned_skb);
781}
782EXPORT_SYMBOL(icmp_ndo_send);
783#endif
784
785static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
786{
787 const struct iphdr *iph = (const struct iphdr *) skb->data;
788 const struct net_protocol *ipprot;
789 int protocol = iph->protocol;
790
791 /* Checkin full IP header plus 8 bytes of protocol to
792 * avoid additional coding at protocol handlers.
793 */
794 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
795 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
796 return;
797 }
798
799 raw_icmp_error(skb, protocol, info);
800
801 ipprot = rcu_dereference(inet_protos[protocol]);
802 if (ipprot && ipprot->err_handler)
803 ipprot->err_handler(skb, info);
804}
805
806static bool icmp_tag_validation(int proto)
807{
808 bool ok;
809
810 rcu_read_lock();
811 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
812 rcu_read_unlock();
813 return ok;
814}
815
816/*
817 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
818 * ICMP_PARAMETERPROB.
819 */
820
821static bool icmp_unreach(struct sk_buff *skb)
822{
823 const struct iphdr *iph;
824 struct icmphdr *icmph;
825 struct net *net;
826 u32 info = 0;
827
828 net = dev_net(skb_dst(skb)->dev);
829
830 /*
831 * Incomplete header ?
832 * Only checks for the IP header, there should be an
833 * additional check for longer headers in upper levels.
834 */
835
836 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
837 goto out_err;
838
839 icmph = icmp_hdr(skb);
840 iph = (const struct iphdr *)skb->data;
841
842 if (iph->ihl < 5) /* Mangled header, drop. */
843 goto out_err;
844
845 switch (icmph->type) {
846 case ICMP_DEST_UNREACH:
847 switch (icmph->code & 15) {
848 case ICMP_NET_UNREACH:
849 case ICMP_HOST_UNREACH:
850 case ICMP_PROT_UNREACH:
851 case ICMP_PORT_UNREACH:
852 break;
853 case ICMP_FRAG_NEEDED:
854 /* for documentation of the ip_no_pmtu_disc
855 * values please see
856 * Documentation/networking/ip-sysctl.rst
857 */
858 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
859 default:
860 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
861 &iph->daddr);
862 break;
863 case 2:
864 goto out;
865 case 3:
866 if (!icmp_tag_validation(iph->protocol))
867 goto out;
868 fallthrough;
869 case 0:
870 info = ntohs(icmph->un.frag.mtu);
871 }
872 break;
873 case ICMP_SR_FAILED:
874 net_dbg_ratelimited("%pI4: Source Route Failed\n",
875 &iph->daddr);
876 break;
877 default:
878 break;
879 }
880 if (icmph->code > NR_ICMP_UNREACH)
881 goto out;
882 break;
883 case ICMP_PARAMETERPROB:
884 info = ntohl(icmph->un.gateway) >> 24;
885 break;
886 case ICMP_TIME_EXCEEDED:
887 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
888 if (icmph->code == ICMP_EXC_FRAGTIME)
889 goto out;
890 break;
891 }
892
893 /*
894 * Throw it at our lower layers
895 *
896 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
897 * header.
898 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
899 * transport layer.
900 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
901 * transport layer.
902 */
903
904 /*
905 * Check the other end isn't violating RFC 1122. Some routers send
906 * bogus responses to broadcast frames. If you see this message
907 * first check your netmask matches at both ends, if it does then
908 * get the other vendor to fix their kit.
909 */
910
911 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
912 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
913 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
914 &ip_hdr(skb)->saddr,
915 icmph->type, icmph->code,
916 &iph->daddr, skb->dev->name);
917 goto out;
918 }
919
920 icmp_socket_deliver(skb, info);
921
922out:
923 return true;
924out_err:
925 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
926 return false;
927}
928
929
930/*
931 * Handle ICMP_REDIRECT.
932 */
933
934static bool icmp_redirect(struct sk_buff *skb)
935{
936 if (skb->len < sizeof(struct iphdr)) {
937 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
938 return false;
939 }
940
941 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
942 /* there aught to be a stat */
943 return false;
944 }
945
946 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
947 return true;
948}
949
950/*
951 * Handle ICMP_ECHO ("ping") requests.
952 *
953 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
954 * requests.
955 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
956 * included in the reply.
957 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
958 * echo requests, MUST have default=NOT.
959 * See also WRT handling of options once they are done and working.
960 */
961
962static bool icmp_echo(struct sk_buff *skb)
963{
964 struct net *net;
965
966 net = dev_net(skb_dst(skb)->dev);
967 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
968 struct icmp_bxm icmp_param;
969
970 icmp_param.data.icmph = *icmp_hdr(skb);
971 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
972 icmp_param.skb = skb;
973 icmp_param.offset = 0;
974 icmp_param.data_len = skb->len;
975 icmp_param.head_len = sizeof(struct icmphdr);
976 icmp_reply(&icmp_param, skb);
977 }
978 /* should there be an ICMP stat for ignored echos? */
979 return true;
980}
981
982/*
983 * Handle ICMP Timestamp requests.
984 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
985 * SHOULD be in the kernel for minimum random latency.
986 * MUST be accurate to a few minutes.
987 * MUST be updated at least at 15Hz.
988 */
989static bool icmp_timestamp(struct sk_buff *skb)
990{
991 struct icmp_bxm icmp_param;
992 /*
993 * Too short.
994 */
995 if (skb->len < 4)
996 goto out_err;
997
998 /*
999 * Fill in the current time as ms since midnight UT:
1000 */
1001 icmp_param.data.times[1] = inet_current_timestamp();
1002 icmp_param.data.times[2] = icmp_param.data.times[1];
1003
1004 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1005
1006 icmp_param.data.icmph = *icmp_hdr(skb);
1007 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1008 icmp_param.data.icmph.code = 0;
1009 icmp_param.skb = skb;
1010 icmp_param.offset = 0;
1011 icmp_param.data_len = 0;
1012 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1013 icmp_reply(&icmp_param, skb);
1014 return true;
1015
1016out_err:
1017 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1018 return false;
1019}
1020
1021static bool icmp_discard(struct sk_buff *skb)
1022{
1023 /* pretend it was a success */
1024 return true;
1025}
1026
1027/*
1028 * Deal with incoming ICMP packets.
1029 */
1030int icmp_rcv(struct sk_buff *skb)
1031{
1032 struct icmphdr *icmph;
1033 struct rtable *rt = skb_rtable(skb);
1034 struct net *net = dev_net(rt->dst.dev);
1035 bool success;
1036
1037 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1038 struct sec_path *sp = skb_sec_path(skb);
1039 int nh;
1040
1041 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1042 XFRM_STATE_ICMP))
1043 goto drop;
1044
1045 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1046 goto drop;
1047
1048 nh = skb_network_offset(skb);
1049 skb_set_network_header(skb, sizeof(*icmph));
1050
1051 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1052 goto drop;
1053
1054 skb_set_network_header(skb, nh);
1055 }
1056
1057 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1058
1059 if (skb_checksum_simple_validate(skb))
1060 goto csum_error;
1061
1062 if (!pskb_pull(skb, sizeof(*icmph)))
1063 goto error;
1064
1065 icmph = icmp_hdr(skb);
1066
1067 ICMPMSGIN_INC_STATS(net, icmph->type);
1068 /*
1069 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1070 *
1071 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1072 * discarded.
1073 */
1074 if (icmph->type > NR_ICMP_TYPES)
1075 goto error;
1076
1077
1078 /*
1079 * Parse the ICMP message
1080 */
1081
1082 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1083 /*
1084 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1085 * silently ignored (we let user decide with a sysctl).
1086 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1087 * discarded if to broadcast/multicast.
1088 */
1089 if ((icmph->type == ICMP_ECHO ||
1090 icmph->type == ICMP_TIMESTAMP) &&
1091 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1092 goto error;
1093 }
1094 if (icmph->type != ICMP_ECHO &&
1095 icmph->type != ICMP_TIMESTAMP &&
1096 icmph->type != ICMP_ADDRESS &&
1097 icmph->type != ICMP_ADDRESSREPLY) {
1098 goto error;
1099 }
1100 }
1101
1102 success = icmp_pointers[icmph->type].handler(skb);
1103
1104 if (success) {
1105 consume_skb(skb);
1106 return NET_RX_SUCCESS;
1107 }
1108
1109drop:
1110 kfree_skb(skb);
1111 return NET_RX_DROP;
1112csum_error:
1113 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1114error:
1115 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1116 goto drop;
1117}
1118
1119static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1120{
1121 struct icmp_extobj_hdr *objh, _objh;
1122 struct icmp_ext_hdr *exth, _exth;
1123 u16 olen;
1124
1125 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1126 if (!exth)
1127 return false;
1128 if (exth->version != 2)
1129 return true;
1130
1131 if (exth->checksum &&
1132 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1133 return false;
1134
1135 off += sizeof(_exth);
1136 while (off < skb->len) {
1137 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1138 if (!objh)
1139 return false;
1140
1141 olen = ntohs(objh->length);
1142 if (olen < sizeof(_objh))
1143 return false;
1144
1145 off += olen;
1146 if (off > skb->len)
1147 return false;
1148 }
1149
1150 return true;
1151}
1152
1153void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1154 struct sock_ee_data_rfc4884 *out,
1155 int thlen, int off)
1156{
1157 int hlen;
1158
1159 /* original datagram headers: end of icmph to payload (skb->data) */
1160 hlen = -skb_transport_offset(skb) - thlen;
1161
1162 /* per rfc 4884: minimal datagram length of 128 bytes */
1163 if (off < 128 || off < hlen)
1164 return;
1165
1166 /* kernel has stripped headers: return payload offset in bytes */
1167 off -= hlen;
1168 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1169 return;
1170
1171 out->len = off;
1172
1173 if (!ip_icmp_error_rfc4884_validate(skb, off))
1174 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1175}
1176EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1177
1178int icmp_err(struct sk_buff *skb, u32 info)
1179{
1180 struct iphdr *iph = (struct iphdr *)skb->data;
1181 int offset = iph->ihl<<2;
1182 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1183 int type = icmp_hdr(skb)->type;
1184 int code = icmp_hdr(skb)->code;
1185 struct net *net = dev_net(skb->dev);
1186
1187 /*
1188 * Use ping_err to handle all icmp errors except those
1189 * triggered by ICMP_ECHOREPLY which sent from kernel.
1190 */
1191 if (icmph->type != ICMP_ECHOREPLY) {
1192 ping_err(skb, offset, info);
1193 return 0;
1194 }
1195
1196 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1197 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1198 else if (type == ICMP_REDIRECT)
1199 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1200
1201 return 0;
1202}
1203
1204/*
1205 * This table is the definition of how we handle ICMP.
1206 */
1207static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1208 [ICMP_ECHOREPLY] = {
1209 .handler = ping_rcv,
1210 },
1211 [1] = {
1212 .handler = icmp_discard,
1213 .error = 1,
1214 },
1215 [2] = {
1216 .handler = icmp_discard,
1217 .error = 1,
1218 },
1219 [ICMP_DEST_UNREACH] = {
1220 .handler = icmp_unreach,
1221 .error = 1,
1222 },
1223 [ICMP_SOURCE_QUENCH] = {
1224 .handler = icmp_unreach,
1225 .error = 1,
1226 },
1227 [ICMP_REDIRECT] = {
1228 .handler = icmp_redirect,
1229 .error = 1,
1230 },
1231 [6] = {
1232 .handler = icmp_discard,
1233 .error = 1,
1234 },
1235 [7] = {
1236 .handler = icmp_discard,
1237 .error = 1,
1238 },
1239 [ICMP_ECHO] = {
1240 .handler = icmp_echo,
1241 },
1242 [9] = {
1243 .handler = icmp_discard,
1244 .error = 1,
1245 },
1246 [10] = {
1247 .handler = icmp_discard,
1248 .error = 1,
1249 },
1250 [ICMP_TIME_EXCEEDED] = {
1251 .handler = icmp_unreach,
1252 .error = 1,
1253 },
1254 [ICMP_PARAMETERPROB] = {
1255 .handler = icmp_unreach,
1256 .error = 1,
1257 },
1258 [ICMP_TIMESTAMP] = {
1259 .handler = icmp_timestamp,
1260 },
1261 [ICMP_TIMESTAMPREPLY] = {
1262 .handler = icmp_discard,
1263 },
1264 [ICMP_INFO_REQUEST] = {
1265 .handler = icmp_discard,
1266 },
1267 [ICMP_INFO_REPLY] = {
1268 .handler = icmp_discard,
1269 },
1270 [ICMP_ADDRESS] = {
1271 .handler = icmp_discard,
1272 },
1273 [ICMP_ADDRESSREPLY] = {
1274 .handler = icmp_discard,
1275 },
1276};
1277
1278static void __net_exit icmp_sk_exit(struct net *net)
1279{
1280 int i;
1281
1282 for_each_possible_cpu(i)
1283 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1284 free_percpu(net->ipv4.icmp_sk);
1285 net->ipv4.icmp_sk = NULL;
1286}
1287
1288static int __net_init icmp_sk_init(struct net *net)
1289{
1290 int i, err;
1291
1292 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1293 if (!net->ipv4.icmp_sk)
1294 return -ENOMEM;
1295
1296 for_each_possible_cpu(i) {
1297 struct sock *sk;
1298
1299 err = inet_ctl_sock_create(&sk, PF_INET,
1300 SOCK_RAW, IPPROTO_ICMP, net);
1301 if (err < 0)
1302 goto fail;
1303
1304 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1305
1306 /* Enough space for 2 64K ICMP packets, including
1307 * sk_buff/skb_shared_info struct overhead.
1308 */
1309 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1310
1311 /*
1312 * Speedup sock_wfree()
1313 */
1314 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1315 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1316 }
1317
1318 /* Control parameters for ECHO replies. */
1319 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1320 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1321
1322 /* Control parameter - ignore bogus broadcast responses? */
1323 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1324
1325 /*
1326 * Configurable global rate limit.
1327 *
1328 * ratelimit defines tokens/packet consumed for dst->rate_token
1329 * bucket ratemask defines which icmp types are ratelimited by
1330 * setting it's bit position.
1331 *
1332 * default:
1333 * dest unreachable (3), source quench (4),
1334 * time exceeded (11), parameter problem (12)
1335 */
1336
1337 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1338 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1339 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1340
1341 return 0;
1342
1343fail:
1344 icmp_sk_exit(net);
1345 return err;
1346}
1347
1348static struct pernet_operations __net_initdata icmp_sk_ops = {
1349 .init = icmp_sk_init,
1350 .exit = icmp_sk_exit,
1351};
1352
1353int __init icmp_init(void)
1354{
1355 return register_pernet_subsys(&icmp_sk_ops);
1356}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * NET3: Implementation of the ICMP protocol layer.
4 *
5 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
6 *
7 * Some of the function names and the icmp unreach table for this
8 * module were derived from [icmp.c 1.0.11 06/02/93] by
9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
10 * Other than that this module is a complete rewrite.
11 *
12 * Fixes:
13 * Clemens Fruhwirth : introduce global icmp rate limiting
14 * with icmp type masking ability instead
15 * of broken per type icmp timeouts.
16 * Mike Shaver : RFC1122 checks.
17 * Alan Cox : Multicast ping reply as self.
18 * Alan Cox : Fix atomicity lockup in ip_build_xmit
19 * call.
20 * Alan Cox : Added 216,128 byte paths to the MTU
21 * code.
22 * Martin Mares : RFC1812 checks.
23 * Martin Mares : Can be configured to follow redirects
24 * if acting as a router _without_ a
25 * routing protocol (RFC 1812).
26 * Martin Mares : Echo requests may be configured to
27 * be ignored (RFC 1812).
28 * Martin Mares : Limitation of ICMP error message
29 * transmit rate (RFC 1812).
30 * Martin Mares : TOS and Precedence set correctly
31 * (RFC 1812).
32 * Martin Mares : Now copying as much data from the
33 * original packet as we can without
34 * exceeding 576 bytes (RFC 1812).
35 * Willy Konynenberg : Transparent proxying support.
36 * Keith Owens : RFC1191 correction for 4.2BSD based
37 * path MTU bug.
38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
39 * valid (RFC 1812).
40 * Andi Kleen : Check all packet lengths properly
41 * and moved all kfree_skb() up to
42 * icmp_rcv.
43 * Andi Kleen : Move the rate limit bookkeeping
44 * into the dest entry and use a token
45 * bucket filter (thanks to ANK). Make
46 * the rates sysctl configurable.
47 * Yu Tianli : Fixed two ugly bugs in icmp_send
48 * - IP option length was accounted wrongly
49 * - ICMP header length was not accounted
50 * at all.
51 * Tristan Greaves : Added sysctl option to ignore bogus
52 * broadcast responses from broken routers.
53 *
54 * To Fix:
55 *
56 * - Should use skb_pull() instead of all the manual checking.
57 * This would also greatly simply some upper layer error handlers. --AK
58 */
59
60#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61
62#include <linux/module.h>
63#include <linux/types.h>
64#include <linux/jiffies.h>
65#include <linux/kernel.h>
66#include <linux/fcntl.h>
67#include <linux/socket.h>
68#include <linux/in.h>
69#include <linux/inet.h>
70#include <linux/inetdevice.h>
71#include <linux/netdevice.h>
72#include <linux/string.h>
73#include <linux/netfilter_ipv4.h>
74#include <linux/slab.h>
75#include <net/snmp.h>
76#include <net/ip.h>
77#include <net/route.h>
78#include <net/protocol.h>
79#include <net/icmp.h>
80#include <net/tcp.h>
81#include <net/udp.h>
82#include <net/raw.h>
83#include <net/ping.h>
84#include <linux/skbuff.h>
85#include <net/sock.h>
86#include <linux/errno.h>
87#include <linux/timer.h>
88#include <linux/init.h>
89#include <linux/uaccess.h>
90#include <net/checksum.h>
91#include <net/xfrm.h>
92#include <net/inet_common.h>
93#include <net/ip_fib.h>
94#include <net/l3mdev.h>
95#include <net/addrconf.h>
96#include <net/inet_dscp.h>
97#define CREATE_TRACE_POINTS
98#include <trace/events/icmp.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 enum skb_drop_reason (*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
199static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk);
200
201/* Called with BH disabled */
202static inline struct sock *icmp_xmit_lock(struct net *net)
203{
204 struct sock *sk;
205
206 sk = this_cpu_read(ipv4_icmp_sk);
207
208 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
209 /* This can happen if the output path signals a
210 * dst_link_failure() for an outgoing ICMP packet.
211 */
212 return NULL;
213 }
214 sock_net_set(sk, net);
215 return sk;
216}
217
218static inline void icmp_xmit_unlock(struct sock *sk)
219{
220 sock_net_set(sk, &init_net);
221 spin_unlock(&sk->sk_lock.slock);
222}
223
224/**
225 * icmp_global_allow - Are we allowed to send one more ICMP message ?
226 * @net: network namespace
227 *
228 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
229 * Returns false if we reached the limit and can not send another packet.
230 * Works in tandem with icmp_global_consume().
231 */
232bool icmp_global_allow(struct net *net)
233{
234 u32 delta, now, oldstamp;
235 int incr, new, old;
236
237 /* Note: many cpus could find this condition true.
238 * Then later icmp_global_consume() could consume more credits,
239 * this is an acceptable race.
240 */
241 if (atomic_read(&net->ipv4.icmp_global_credit) > 0)
242 return true;
243
244 now = jiffies;
245 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp);
246 delta = min_t(u32, now - oldstamp, HZ);
247 if (delta < HZ / 50)
248 return false;
249
250 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ;
251 if (!incr)
252 return false;
253
254 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) {
255 old = atomic_read(&net->ipv4.icmp_global_credit);
256 do {
257 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst));
258 } while (!atomic_try_cmpxchg(&net->ipv4.icmp_global_credit, &old, new));
259 }
260 return true;
261}
262EXPORT_SYMBOL(icmp_global_allow);
263
264void icmp_global_consume(struct net *net)
265{
266 int credits = get_random_u32_below(3);
267
268 /* Note: this might make icmp_global.credit negative. */
269 if (credits)
270 atomic_sub(credits, &net->ipv4.icmp_global_credit);
271}
272EXPORT_SYMBOL(icmp_global_consume);
273
274static bool icmpv4_mask_allow(struct net *net, int type, int code)
275{
276 if (type > NR_ICMP_TYPES)
277 return true;
278
279 /* Don't limit PMTU discovery. */
280 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
281 return true;
282
283 /* Limit if icmp type is enabled in ratemask. */
284 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
285 return true;
286
287 return false;
288}
289
290static bool icmpv4_global_allow(struct net *net, int type, int code,
291 bool *apply_ratelimit)
292{
293 if (icmpv4_mask_allow(net, type, code))
294 return true;
295
296 if (icmp_global_allow(net)) {
297 *apply_ratelimit = true;
298 return true;
299 }
300 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
301 return false;
302}
303
304/*
305 * Send an ICMP frame.
306 */
307
308static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
309 struct flowi4 *fl4, int type, int code,
310 bool apply_ratelimit)
311{
312 struct dst_entry *dst = &rt->dst;
313 struct inet_peer *peer;
314 bool rc = true;
315
316 if (!apply_ratelimit)
317 return true;
318
319 /* No rate limit on loopback */
320 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
321 goto out;
322
323 rcu_read_lock();
324 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr,
325 l3mdev_master_ifindex_rcu(dst->dev));
326 rc = inet_peer_xrlim_allow(peer,
327 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
328 rcu_read_unlock();
329out:
330 if (!rc)
331 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST);
332 else
333 icmp_global_consume(net);
334 return rc;
335}
336
337/*
338 * Maintain the counters used in the SNMP statistics for outgoing ICMP
339 */
340void icmp_out_count(struct net *net, unsigned char type)
341{
342 ICMPMSGOUT_INC_STATS(net, type);
343 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
344}
345
346/*
347 * Checksum each fragment, and on the first include the headers and final
348 * checksum.
349 */
350static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
351 struct sk_buff *skb)
352{
353 struct icmp_bxm *icmp_param = from;
354 __wsum csum;
355
356 csum = skb_copy_and_csum_bits(icmp_param->skb,
357 icmp_param->offset + offset,
358 to, len);
359
360 skb->csum = csum_block_add(skb->csum, csum, odd);
361 if (icmp_pointers[icmp_param->data.icmph.type].error)
362 nf_ct_attach(skb, icmp_param->skb);
363 return 0;
364}
365
366static void icmp_push_reply(struct sock *sk,
367 struct icmp_bxm *icmp_param,
368 struct flowi4 *fl4,
369 struct ipcm_cookie *ipc, struct rtable **rt)
370{
371 struct sk_buff *skb;
372
373 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
374 icmp_param->data_len+icmp_param->head_len,
375 icmp_param->head_len,
376 ipc, rt, MSG_DONTWAIT) < 0) {
377 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
378 ip_flush_pending_frames(sk);
379 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
380 struct icmphdr *icmph = icmp_hdr(skb);
381 __wsum csum;
382 struct sk_buff *skb1;
383
384 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
385 (char *)icmph,
386 icmp_param->head_len);
387 skb_queue_walk(&sk->sk_write_queue, skb1) {
388 csum = csum_add(csum, skb1->csum);
389 }
390 icmph->checksum = csum_fold(csum);
391 skb->ip_summed = CHECKSUM_NONE;
392 ip_push_pending_frames(sk, fl4);
393 }
394}
395
396/*
397 * Driving logic for building and sending ICMP messages.
398 */
399
400static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
401{
402 struct rtable *rt = skb_rtable(skb);
403 struct net *net = dev_net_rcu(rt->dst.dev);
404 bool apply_ratelimit = false;
405 struct ipcm_cookie ipc;
406 struct flowi4 fl4;
407 struct sock *sk;
408 struct inet_sock *inet;
409 __be32 daddr, saddr;
410 u32 mark = IP4_REPLY_MARK(net, skb->mark);
411 int type = icmp_param->data.icmph.type;
412 int code = icmp_param->data.icmph.code;
413
414 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
415 return;
416
417 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */
418 local_bh_disable();
419
420 /* is global icmp_msgs_per_sec exhausted ? */
421 if (!icmpv4_global_allow(net, type, code, &apply_ratelimit))
422 goto out_bh_enable;
423
424 sk = icmp_xmit_lock(net);
425 if (!sk)
426 goto out_bh_enable;
427 inet = inet_sk(sk);
428
429 icmp_param->data.icmph.checksum = 0;
430
431 ipcm_init(&ipc);
432 inet->tos = ip_hdr(skb)->tos;
433 ipc.sockc.mark = mark;
434 daddr = ipc.addr = ip_hdr(skb)->saddr;
435 saddr = fib_compute_spec_dst(skb);
436
437 if (icmp_param->replyopts.opt.opt.optlen) {
438 ipc.opt = &icmp_param->replyopts.opt;
439 if (ipc.opt->opt.srr)
440 daddr = icmp_param->replyopts.opt.opt.faddr;
441 }
442 memset(&fl4, 0, sizeof(fl4));
443 fl4.daddr = daddr;
444 fl4.saddr = saddr;
445 fl4.flowi4_mark = mark;
446 fl4.flowi4_uid = sock_net_uid(net, NULL);
447 fl4.flowi4_tos = inet_dscp_to_dsfield(ip4h_dscp(ip_hdr(skb)));
448 fl4.flowi4_proto = IPPROTO_ICMP;
449 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
450 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
451 rt = ip_route_output_key(net, &fl4);
452 if (IS_ERR(rt))
453 goto out_unlock;
454 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit))
455 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
456 ip_rt_put(rt);
457out_unlock:
458 icmp_xmit_unlock(sk);
459out_bh_enable:
460 local_bh_enable();
461}
462
463/*
464 * The device used for looking up which routing table to use for sending an ICMP
465 * error is preferably the source whenever it is set, which should ensure the
466 * icmp error can be sent to the source host, else lookup using the routing
467 * table of the destination device, else use the main routing table (index 0).
468 */
469static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
470{
471 struct net_device *route_lookup_dev = NULL;
472
473 if (skb->dev)
474 route_lookup_dev = skb->dev;
475 else if (skb_dst(skb))
476 route_lookup_dev = skb_dst(skb)->dev;
477 return route_lookup_dev;
478}
479
480static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
481 struct sk_buff *skb_in,
482 const struct iphdr *iph, __be32 saddr,
483 dscp_t dscp, u32 mark, int type,
484 int code, struct icmp_bxm *param)
485{
486 struct net_device *route_lookup_dev;
487 struct dst_entry *dst, *dst2;
488 struct rtable *rt, *rt2;
489 struct flowi4 fl4_dec;
490 int err;
491
492 memset(fl4, 0, sizeof(*fl4));
493 fl4->daddr = (param->replyopts.opt.opt.srr ?
494 param->replyopts.opt.opt.faddr : iph->saddr);
495 fl4->saddr = saddr;
496 fl4->flowi4_mark = mark;
497 fl4->flowi4_uid = sock_net_uid(net, NULL);
498 fl4->flowi4_tos = inet_dscp_to_dsfield(dscp);
499 fl4->flowi4_proto = IPPROTO_ICMP;
500 fl4->fl4_icmp_type = type;
501 fl4->fl4_icmp_code = code;
502 route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
503 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
504
505 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
506 rt = ip_route_output_key_hash(net, fl4, skb_in);
507 if (IS_ERR(rt))
508 return rt;
509
510 /* No need to clone since we're just using its address. */
511 rt2 = rt;
512
513 dst = xfrm_lookup(net, &rt->dst,
514 flowi4_to_flowi(fl4), NULL, 0);
515 rt = dst_rtable(dst);
516 if (!IS_ERR(dst)) {
517 if (rt != rt2)
518 return rt;
519 if (inet_addr_type_dev_table(net, route_lookup_dev,
520 fl4->daddr) == RTN_LOCAL)
521 return rt;
522 } else if (PTR_ERR(dst) == -EPERM) {
523 rt = NULL;
524 } else {
525 return rt;
526 }
527 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
528 if (err)
529 goto relookup_failed;
530
531 if (inet_addr_type_dev_table(net, route_lookup_dev,
532 fl4_dec.saddr) == RTN_LOCAL) {
533 rt2 = __ip_route_output_key(net, &fl4_dec);
534 if (IS_ERR(rt2))
535 err = PTR_ERR(rt2);
536 } else {
537 struct flowi4 fl4_2 = {};
538 unsigned long orefdst;
539
540 fl4_2.daddr = fl4_dec.saddr;
541 rt2 = ip_route_output_key(net, &fl4_2);
542 if (IS_ERR(rt2)) {
543 err = PTR_ERR(rt2);
544 goto relookup_failed;
545 }
546 /* Ugh! */
547 orefdst = skb_in->_skb_refdst; /* save old refdst */
548 skb_dst_set(skb_in, NULL);
549 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
550 dscp, rt2->dst.dev) ? -EINVAL : 0;
551
552 dst_release(&rt2->dst);
553 rt2 = skb_rtable(skb_in);
554 skb_in->_skb_refdst = orefdst; /* restore old refdst */
555 }
556
557 if (err)
558 goto relookup_failed;
559
560 dst2 = xfrm_lookup(net, &rt2->dst, flowi4_to_flowi(&fl4_dec), NULL,
561 XFRM_LOOKUP_ICMP);
562 rt2 = dst_rtable(dst2);
563 if (!IS_ERR(dst2)) {
564 dst_release(&rt->dst);
565 memcpy(fl4, &fl4_dec, sizeof(*fl4));
566 rt = rt2;
567 } else if (PTR_ERR(dst2) == -EPERM) {
568 if (rt)
569 dst_release(&rt->dst);
570 return rt2;
571 } else {
572 err = PTR_ERR(dst2);
573 goto relookup_failed;
574 }
575 return rt;
576
577relookup_failed:
578 if (rt)
579 return rt;
580 return ERR_PTR(err);
581}
582
583/*
584 * Send an ICMP message in response to a situation
585 *
586 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
587 * MAY send more (we do).
588 * MUST NOT change this header information.
589 * MUST NOT reply to a multicast/broadcast IP address.
590 * MUST NOT reply to a multicast/broadcast MAC address.
591 * MUST reply to only the first fragment.
592 */
593
594void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
595 const struct ip_options *opt)
596{
597 struct iphdr *iph;
598 int room;
599 struct icmp_bxm icmp_param;
600 struct rtable *rt = skb_rtable(skb_in);
601 bool apply_ratelimit = false;
602 struct ipcm_cookie ipc;
603 struct flowi4 fl4;
604 __be32 saddr;
605 u8 tos;
606 u32 mark;
607 struct net *net;
608 struct sock *sk;
609
610 if (!rt)
611 return;
612
613 rcu_read_lock();
614
615 if (rt->dst.dev)
616 net = dev_net_rcu(rt->dst.dev);
617 else if (skb_in->dev)
618 net = dev_net_rcu(skb_in->dev);
619 else
620 goto out;
621
622 /*
623 * Find the original header. It is expected to be valid, of course.
624 * Check this, icmp_send is called from the most obscure devices
625 * sometimes.
626 */
627 iph = ip_hdr(skb_in);
628
629 if ((u8 *)iph < skb_in->head ||
630 (skb_network_header(skb_in) + sizeof(*iph)) >
631 skb_tail_pointer(skb_in))
632 goto out;
633
634 /*
635 * No replies to physical multicast/broadcast
636 */
637 if (skb_in->pkt_type != PACKET_HOST)
638 goto out;
639
640 /*
641 * Now check at the protocol level
642 */
643 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
644 goto out;
645
646 /*
647 * Only reply to fragment 0. We byte re-order the constant
648 * mask for efficiency.
649 */
650 if (iph->frag_off & htons(IP_OFFSET))
651 goto out;
652
653 /*
654 * If we send an ICMP error to an ICMP error a mess would result..
655 */
656 if (icmp_pointers[type].error) {
657 /*
658 * We are an error, check if we are replying to an
659 * ICMP error
660 */
661 if (iph->protocol == IPPROTO_ICMP) {
662 u8 _inner_type, *itp;
663
664 itp = skb_header_pointer(skb_in,
665 skb_network_header(skb_in) +
666 (iph->ihl << 2) +
667 offsetof(struct icmphdr,
668 type) -
669 skb_in->data,
670 sizeof(_inner_type),
671 &_inner_type);
672 if (!itp)
673 goto out;
674
675 /*
676 * Assume any unknown ICMP type is an error. This
677 * isn't specified by the RFC, but think about it..
678 */
679 if (*itp > NR_ICMP_TYPES ||
680 icmp_pointers[*itp].error)
681 goto out;
682 }
683 }
684
685 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */
686 local_bh_disable();
687
688 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
689 * incoming dev is loopback. If outgoing dev change to not be
690 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
691 */
692 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
693 !icmpv4_global_allow(net, type, code, &apply_ratelimit))
694 goto out_bh_enable;
695
696 sk = icmp_xmit_lock(net);
697 if (!sk)
698 goto out_bh_enable;
699
700 /*
701 * Construct source address and options.
702 */
703
704 saddr = iph->daddr;
705 if (!(rt->rt_flags & RTCF_LOCAL)) {
706 struct net_device *dev = NULL;
707
708 rcu_read_lock();
709 if (rt_is_input_route(rt) &&
710 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
711 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
712
713 if (dev)
714 saddr = inet_select_addr(dev, iph->saddr,
715 RT_SCOPE_LINK);
716 else
717 saddr = 0;
718 rcu_read_unlock();
719 }
720
721 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
722 IPTOS_PREC_INTERNETCONTROL) :
723 iph->tos;
724 mark = IP4_REPLY_MARK(net, skb_in->mark);
725
726 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
727 goto out_unlock;
728
729
730 /*
731 * Prepare data for ICMP header.
732 */
733
734 icmp_param.data.icmph.type = type;
735 icmp_param.data.icmph.code = code;
736 icmp_param.data.icmph.un.gateway = info;
737 icmp_param.data.icmph.checksum = 0;
738 icmp_param.skb = skb_in;
739 icmp_param.offset = skb_network_offset(skb_in);
740 inet_sk(sk)->tos = tos;
741 ipcm_init(&ipc);
742 ipc.addr = iph->saddr;
743 ipc.opt = &icmp_param.replyopts.opt;
744 ipc.sockc.mark = mark;
745
746 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr,
747 inet_dsfield_to_dscp(tos), mark, type, code,
748 &icmp_param);
749 if (IS_ERR(rt))
750 goto out_unlock;
751
752 /* peer icmp_ratelimit */
753 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code, apply_ratelimit))
754 goto ende;
755
756 /* RFC says return as much as we can without exceeding 576 bytes. */
757
758 room = dst_mtu(&rt->dst);
759 if (room > 576)
760 room = 576;
761 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
762 room -= sizeof(struct icmphdr);
763 /* Guard against tiny mtu. We need to include at least one
764 * IP network header for this message to make any sense.
765 */
766 if (room <= (int)sizeof(struct iphdr))
767 goto ende;
768
769 icmp_param.data_len = skb_in->len - icmp_param.offset;
770 if (icmp_param.data_len > room)
771 icmp_param.data_len = room;
772 icmp_param.head_len = sizeof(struct icmphdr);
773
774 /* if we don't have a source address at this point, fall back to the
775 * dummy address instead of sending out a packet with a source address
776 * of 0.0.0.0
777 */
778 if (!fl4.saddr)
779 fl4.saddr = htonl(INADDR_DUMMY);
780
781 trace_icmp_send(skb_in, type, code);
782
783 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
784ende:
785 ip_rt_put(rt);
786out_unlock:
787 icmp_xmit_unlock(sk);
788out_bh_enable:
789 local_bh_enable();
790out:
791 rcu_read_unlock();
792}
793EXPORT_SYMBOL(__icmp_send);
794
795#if IS_ENABLED(CONFIG_NF_NAT)
796#include <net/netfilter/nf_conntrack.h>
797void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
798{
799 struct sk_buff *cloned_skb = NULL;
800 struct ip_options opts = { 0 };
801 enum ip_conntrack_info ctinfo;
802 struct nf_conn *ct;
803 __be32 orig_ip;
804
805 ct = nf_ct_get(skb_in, &ctinfo);
806 if (!ct || !(ct->status & IPS_SRC_NAT)) {
807 __icmp_send(skb_in, type, code, info, &opts);
808 return;
809 }
810
811 if (skb_shared(skb_in))
812 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
813
814 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
815 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
816 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
817 skb_network_offset(skb_in) + sizeof(struct iphdr))))
818 goto out;
819
820 orig_ip = ip_hdr(skb_in)->saddr;
821 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
822 __icmp_send(skb_in, type, code, info, &opts);
823 ip_hdr(skb_in)->saddr = orig_ip;
824out:
825 consume_skb(cloned_skb);
826}
827EXPORT_SYMBOL(icmp_ndo_send);
828#endif
829
830static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
831{
832 const struct iphdr *iph = (const struct iphdr *)skb->data;
833 const struct net_protocol *ipprot;
834 int protocol = iph->protocol;
835
836 /* Checkin full IP header plus 8 bytes of protocol to
837 * avoid additional coding at protocol handlers.
838 */
839 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
840 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
841 return;
842 }
843
844 raw_icmp_error(skb, protocol, info);
845
846 ipprot = rcu_dereference(inet_protos[protocol]);
847 if (ipprot && ipprot->err_handler)
848 ipprot->err_handler(skb, info);
849}
850
851static bool icmp_tag_validation(int proto)
852{
853 bool ok;
854
855 rcu_read_lock();
856 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
857 rcu_read_unlock();
858 return ok;
859}
860
861/*
862 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
863 * ICMP_PARAMETERPROB.
864 */
865
866static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
867{
868 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
869 const struct iphdr *iph;
870 struct icmphdr *icmph;
871 struct net *net;
872 u32 info = 0;
873
874 net = dev_net_rcu(skb_dst(skb)->dev);
875
876 /*
877 * Incomplete header ?
878 * Only checks for the IP header, there should be an
879 * additional check for longer headers in upper levels.
880 */
881
882 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
883 goto out_err;
884
885 icmph = icmp_hdr(skb);
886 iph = (const struct iphdr *)skb->data;
887
888 if (iph->ihl < 5) { /* Mangled header, drop. */
889 reason = SKB_DROP_REASON_IP_INHDR;
890 goto out_err;
891 }
892
893 switch (icmph->type) {
894 case ICMP_DEST_UNREACH:
895 switch (icmph->code & 15) {
896 case ICMP_NET_UNREACH:
897 case ICMP_HOST_UNREACH:
898 case ICMP_PROT_UNREACH:
899 case ICMP_PORT_UNREACH:
900 break;
901 case ICMP_FRAG_NEEDED:
902 /* for documentation of the ip_no_pmtu_disc
903 * values please see
904 * Documentation/networking/ip-sysctl.rst
905 */
906 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
907 default:
908 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
909 &iph->daddr);
910 break;
911 case 2:
912 goto out;
913 case 3:
914 if (!icmp_tag_validation(iph->protocol))
915 goto out;
916 fallthrough;
917 case 0:
918 info = ntohs(icmph->un.frag.mtu);
919 }
920 break;
921 case ICMP_SR_FAILED:
922 net_dbg_ratelimited("%pI4: Source Route Failed\n",
923 &iph->daddr);
924 break;
925 default:
926 break;
927 }
928 if (icmph->code > NR_ICMP_UNREACH)
929 goto out;
930 break;
931 case ICMP_PARAMETERPROB:
932 info = ntohl(icmph->un.gateway) >> 24;
933 break;
934 case ICMP_TIME_EXCEEDED:
935 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
936 if (icmph->code == ICMP_EXC_FRAGTIME)
937 goto out;
938 break;
939 }
940
941 /*
942 * Throw it at our lower layers
943 *
944 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
945 * header.
946 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
947 * transport layer.
948 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
949 * transport layer.
950 */
951
952 /*
953 * Check the other end isn't violating RFC 1122. Some routers send
954 * bogus responses to broadcast frames. If you see this message
955 * first check your netmask matches at both ends, if it does then
956 * get the other vendor to fix their kit.
957 */
958
959 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
960 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
961 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
962 &ip_hdr(skb)->saddr,
963 icmph->type, icmph->code,
964 &iph->daddr, skb->dev->name);
965 goto out;
966 }
967
968 icmp_socket_deliver(skb, info);
969
970out:
971 return reason;
972out_err:
973 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
974 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
975}
976
977
978/*
979 * Handle ICMP_REDIRECT.
980 */
981
982static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
983{
984 if (skb->len < sizeof(struct iphdr)) {
985 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
986 return SKB_DROP_REASON_PKT_TOO_SMALL;
987 }
988
989 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
990 /* there aught to be a stat */
991 return SKB_DROP_REASON_NOMEM;
992 }
993
994 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
995 return SKB_NOT_DROPPED_YET;
996}
997
998/*
999 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
1000 *
1001 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
1002 * requests.
1003 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
1004 * included in the reply.
1005 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
1006 * echo requests, MUST have default=NOT.
1007 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
1008 * Extended Echo Functionality, MUST be disabled by default
1009 * See also WRT handling of options once they are done and working.
1010 */
1011
1012static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
1013{
1014 struct icmp_bxm icmp_param;
1015 struct net *net;
1016
1017 net = dev_net_rcu(skb_dst(skb)->dev);
1018 /* should there be an ICMP stat for ignored echos? */
1019 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1020 return SKB_NOT_DROPPED_YET;
1021
1022 icmp_param.data.icmph = *icmp_hdr(skb);
1023 icmp_param.skb = skb;
1024 icmp_param.offset = 0;
1025 icmp_param.data_len = skb->len;
1026 icmp_param.head_len = sizeof(struct icmphdr);
1027
1028 if (icmp_param.data.icmph.type == ICMP_ECHO)
1029 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1030 else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1031 return SKB_NOT_DROPPED_YET;
1032
1033 icmp_reply(&icmp_param, skb);
1034 return SKB_NOT_DROPPED_YET;
1035}
1036
1037/* Helper for icmp_echo and icmpv6_echo_reply.
1038 * Searches for net_device that matches PROBE interface identifier
1039 * and builds PROBE reply message in icmphdr.
1040 *
1041 * Returns false if PROBE responses are disabled via sysctl
1042 */
1043
1044bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1045{
1046 struct net *net = dev_net_rcu(skb->dev);
1047 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1048 struct icmp_ext_echo_iio *iio, _iio;
1049 struct inet6_dev *in6_dev;
1050 struct in_device *in_dev;
1051 struct net_device *dev;
1052 char buff[IFNAMSIZ];
1053 u16 ident_len;
1054 u8 status;
1055
1056 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1057 return false;
1058
1059 /* We currently only support probing interfaces on the proxy node
1060 * Check to ensure L-bit is set
1061 */
1062 if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1063 return false;
1064 /* Clear status bits in reply message */
1065 icmphdr->un.echo.sequence &= htons(0xFF00);
1066 if (icmphdr->type == ICMP_EXT_ECHO)
1067 icmphdr->type = ICMP_EXT_ECHOREPLY;
1068 else
1069 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1070 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1071 /* Size of iio is class_type dependent.
1072 * Only check header here and assign length based on ctype in the switch statement
1073 */
1074 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1075 if (!ext_hdr || !iio)
1076 goto send_mal_query;
1077 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1078 ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1079 goto send_mal_query;
1080 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1081 iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1082 sizeof(iio->extobj_hdr) + ident_len, &_iio);
1083 if (!iio)
1084 goto send_mal_query;
1085
1086 status = 0;
1087 dev = NULL;
1088 switch (iio->extobj_hdr.class_type) {
1089 case ICMP_EXT_ECHO_CTYPE_NAME:
1090 if (ident_len >= IFNAMSIZ)
1091 goto send_mal_query;
1092 memset(buff, 0, sizeof(buff));
1093 memcpy(buff, &iio->ident.name, ident_len);
1094 dev = dev_get_by_name(net, buff);
1095 break;
1096 case ICMP_EXT_ECHO_CTYPE_INDEX:
1097 if (ident_len != sizeof(iio->ident.ifindex))
1098 goto send_mal_query;
1099 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1100 break;
1101 case ICMP_EXT_ECHO_CTYPE_ADDR:
1102 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1103 ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1104 iio->ident.addr.ctype3_hdr.addrlen)
1105 goto send_mal_query;
1106 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1107 case ICMP_AFI_IP:
1108 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1109 goto send_mal_query;
1110 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1111 break;
1112#if IS_ENABLED(CONFIG_IPV6)
1113 case ICMP_AFI_IP6:
1114 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1115 goto send_mal_query;
1116 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1117 dev_hold(dev);
1118 break;
1119#endif
1120 default:
1121 goto send_mal_query;
1122 }
1123 break;
1124 default:
1125 goto send_mal_query;
1126 }
1127 if (!dev) {
1128 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1129 return true;
1130 }
1131 /* Fill bits in reply message */
1132 if (dev->flags & IFF_UP)
1133 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1134
1135 in_dev = __in_dev_get_rcu(dev);
1136 if (in_dev && rcu_access_pointer(in_dev->ifa_list))
1137 status |= ICMP_EXT_ECHOREPLY_IPV4;
1138
1139 in6_dev = __in6_dev_get(dev);
1140 if (in6_dev && !list_empty(&in6_dev->addr_list))
1141 status |= ICMP_EXT_ECHOREPLY_IPV6;
1142
1143 dev_put(dev);
1144 icmphdr->un.echo.sequence |= htons(status);
1145 return true;
1146send_mal_query:
1147 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1148 return true;
1149}
1150EXPORT_SYMBOL_GPL(icmp_build_probe);
1151
1152/*
1153 * Handle ICMP Timestamp requests.
1154 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1155 * SHOULD be in the kernel for minimum random latency.
1156 * MUST be accurate to a few minutes.
1157 * MUST be updated at least at 15Hz.
1158 */
1159static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1160{
1161 struct icmp_bxm icmp_param;
1162 /*
1163 * Too short.
1164 */
1165 if (skb->len < 4)
1166 goto out_err;
1167
1168 /*
1169 * Fill in the current time as ms since midnight UT:
1170 */
1171 icmp_param.data.times[1] = inet_current_timestamp();
1172 icmp_param.data.times[2] = icmp_param.data.times[1];
1173
1174 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1175
1176 icmp_param.data.icmph = *icmp_hdr(skb);
1177 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1178 icmp_param.data.icmph.code = 0;
1179 icmp_param.skb = skb;
1180 icmp_param.offset = 0;
1181 icmp_param.data_len = 0;
1182 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1183 icmp_reply(&icmp_param, skb);
1184 return SKB_NOT_DROPPED_YET;
1185
1186out_err:
1187 __ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1188 return SKB_DROP_REASON_PKT_TOO_SMALL;
1189}
1190
1191static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1192{
1193 /* pretend it was a success */
1194 return SKB_NOT_DROPPED_YET;
1195}
1196
1197/*
1198 * Deal with incoming ICMP packets.
1199 */
1200int icmp_rcv(struct sk_buff *skb)
1201{
1202 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1203 struct rtable *rt = skb_rtable(skb);
1204 struct net *net = dev_net_rcu(rt->dst.dev);
1205 struct icmphdr *icmph;
1206
1207 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1208 struct sec_path *sp = skb_sec_path(skb);
1209 int nh;
1210
1211 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1212 XFRM_STATE_ICMP)) {
1213 reason = SKB_DROP_REASON_XFRM_POLICY;
1214 goto drop;
1215 }
1216
1217 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1218 goto drop;
1219
1220 nh = skb_network_offset(skb);
1221 skb_set_network_header(skb, sizeof(*icmph));
1222
1223 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1224 skb)) {
1225 reason = SKB_DROP_REASON_XFRM_POLICY;
1226 goto drop;
1227 }
1228
1229 skb_set_network_header(skb, nh);
1230 }
1231
1232 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1233
1234 if (skb_checksum_simple_validate(skb))
1235 goto csum_error;
1236
1237 if (!pskb_pull(skb, sizeof(*icmph)))
1238 goto error;
1239
1240 icmph = icmp_hdr(skb);
1241
1242 ICMPMSGIN_INC_STATS(net, icmph->type);
1243
1244 /* Check for ICMP Extended Echo (PROBE) messages */
1245 if (icmph->type == ICMP_EXT_ECHO) {
1246 /* We can't use icmp_pointers[].handler() because it is an array of
1247 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1248 */
1249 reason = icmp_echo(skb);
1250 goto reason_check;
1251 }
1252
1253 if (icmph->type == ICMP_EXT_ECHOREPLY) {
1254 reason = ping_rcv(skb);
1255 goto reason_check;
1256 }
1257
1258 /*
1259 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1260 *
1261 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1262 * discarded.
1263 */
1264 if (icmph->type > NR_ICMP_TYPES) {
1265 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1266 goto error;
1267 }
1268
1269 /*
1270 * Parse the ICMP message
1271 */
1272
1273 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1274 /*
1275 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1276 * silently ignored (we let user decide with a sysctl).
1277 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1278 * discarded if to broadcast/multicast.
1279 */
1280 if ((icmph->type == ICMP_ECHO ||
1281 icmph->type == ICMP_TIMESTAMP) &&
1282 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1283 reason = SKB_DROP_REASON_INVALID_PROTO;
1284 goto error;
1285 }
1286 if (icmph->type != ICMP_ECHO &&
1287 icmph->type != ICMP_TIMESTAMP &&
1288 icmph->type != ICMP_ADDRESS &&
1289 icmph->type != ICMP_ADDRESSREPLY) {
1290 reason = SKB_DROP_REASON_INVALID_PROTO;
1291 goto error;
1292 }
1293 }
1294
1295 reason = icmp_pointers[icmph->type].handler(skb);
1296reason_check:
1297 if (!reason) {
1298 consume_skb(skb);
1299 return NET_RX_SUCCESS;
1300 }
1301
1302drop:
1303 kfree_skb_reason(skb, reason);
1304 return NET_RX_DROP;
1305csum_error:
1306 reason = SKB_DROP_REASON_ICMP_CSUM;
1307 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1308error:
1309 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1310 goto drop;
1311}
1312
1313static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1314{
1315 struct icmp_extobj_hdr *objh, _objh;
1316 struct icmp_ext_hdr *exth, _exth;
1317 u16 olen;
1318
1319 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1320 if (!exth)
1321 return false;
1322 if (exth->version != 2)
1323 return true;
1324
1325 if (exth->checksum &&
1326 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1327 return false;
1328
1329 off += sizeof(_exth);
1330 while (off < skb->len) {
1331 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1332 if (!objh)
1333 return false;
1334
1335 olen = ntohs(objh->length);
1336 if (olen < sizeof(_objh))
1337 return false;
1338
1339 off += olen;
1340 if (off > skb->len)
1341 return false;
1342 }
1343
1344 return true;
1345}
1346
1347void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1348 struct sock_ee_data_rfc4884 *out,
1349 int thlen, int off)
1350{
1351 int hlen;
1352
1353 /* original datagram headers: end of icmph to payload (skb->data) */
1354 hlen = -skb_transport_offset(skb) - thlen;
1355
1356 /* per rfc 4884: minimal datagram length of 128 bytes */
1357 if (off < 128 || off < hlen)
1358 return;
1359
1360 /* kernel has stripped headers: return payload offset in bytes */
1361 off -= hlen;
1362 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1363 return;
1364
1365 out->len = off;
1366
1367 if (!ip_icmp_error_rfc4884_validate(skb, off))
1368 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1369}
1370EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1371
1372int icmp_err(struct sk_buff *skb, u32 info)
1373{
1374 struct iphdr *iph = (struct iphdr *)skb->data;
1375 int offset = iph->ihl<<2;
1376 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1377 struct net *net = dev_net_rcu(skb->dev);
1378 int type = icmp_hdr(skb)->type;
1379 int code = icmp_hdr(skb)->code;
1380
1381 /*
1382 * Use ping_err to handle all icmp errors except those
1383 * triggered by ICMP_ECHOREPLY which sent from kernel.
1384 */
1385 if (icmph->type != ICMP_ECHOREPLY) {
1386 ping_err(skb, offset, info);
1387 return 0;
1388 }
1389
1390 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1391 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1392 else if (type == ICMP_REDIRECT)
1393 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1394
1395 return 0;
1396}
1397
1398/*
1399 * This table is the definition of how we handle ICMP.
1400 */
1401static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1402 [ICMP_ECHOREPLY] = {
1403 .handler = ping_rcv,
1404 },
1405 [1] = {
1406 .handler = icmp_discard,
1407 .error = 1,
1408 },
1409 [2] = {
1410 .handler = icmp_discard,
1411 .error = 1,
1412 },
1413 [ICMP_DEST_UNREACH] = {
1414 .handler = icmp_unreach,
1415 .error = 1,
1416 },
1417 [ICMP_SOURCE_QUENCH] = {
1418 .handler = icmp_unreach,
1419 .error = 1,
1420 },
1421 [ICMP_REDIRECT] = {
1422 .handler = icmp_redirect,
1423 .error = 1,
1424 },
1425 [6] = {
1426 .handler = icmp_discard,
1427 .error = 1,
1428 },
1429 [7] = {
1430 .handler = icmp_discard,
1431 .error = 1,
1432 },
1433 [ICMP_ECHO] = {
1434 .handler = icmp_echo,
1435 },
1436 [9] = {
1437 .handler = icmp_discard,
1438 .error = 1,
1439 },
1440 [10] = {
1441 .handler = icmp_discard,
1442 .error = 1,
1443 },
1444 [ICMP_TIME_EXCEEDED] = {
1445 .handler = icmp_unreach,
1446 .error = 1,
1447 },
1448 [ICMP_PARAMETERPROB] = {
1449 .handler = icmp_unreach,
1450 .error = 1,
1451 },
1452 [ICMP_TIMESTAMP] = {
1453 .handler = icmp_timestamp,
1454 },
1455 [ICMP_TIMESTAMPREPLY] = {
1456 .handler = icmp_discard,
1457 },
1458 [ICMP_INFO_REQUEST] = {
1459 .handler = icmp_discard,
1460 },
1461 [ICMP_INFO_REPLY] = {
1462 .handler = icmp_discard,
1463 },
1464 [ICMP_ADDRESS] = {
1465 .handler = icmp_discard,
1466 },
1467 [ICMP_ADDRESSREPLY] = {
1468 .handler = icmp_discard,
1469 },
1470};
1471
1472static int __net_init icmp_sk_init(struct net *net)
1473{
1474 /* Control parameters for ECHO replies. */
1475 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1476 net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1477 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1478
1479 /* Control parameter - ignore bogus broadcast responses? */
1480 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1481
1482 /*
1483 * Configurable global rate limit.
1484 *
1485 * ratelimit defines tokens/packet consumed for dst->rate_token
1486 * bucket ratemask defines which icmp types are ratelimited by
1487 * setting it's bit position.
1488 *
1489 * default:
1490 * dest unreachable (3), source quench (4),
1491 * time exceeded (11), parameter problem (12)
1492 */
1493
1494 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1495 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1496 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1497 net->ipv4.sysctl_icmp_msgs_per_sec = 1000;
1498 net->ipv4.sysctl_icmp_msgs_burst = 50;
1499
1500 return 0;
1501}
1502
1503static struct pernet_operations __net_initdata icmp_sk_ops = {
1504 .init = icmp_sk_init,
1505};
1506
1507int __init icmp_init(void)
1508{
1509 int err, i;
1510
1511 for_each_possible_cpu(i) {
1512 struct sock *sk;
1513
1514 err = inet_ctl_sock_create(&sk, PF_INET,
1515 SOCK_RAW, IPPROTO_ICMP, &init_net);
1516 if (err < 0)
1517 return err;
1518
1519 per_cpu(ipv4_icmp_sk, i) = sk;
1520
1521 /* Enough space for 2 64K ICMP packets, including
1522 * sk_buff/skb_shared_info struct overhead.
1523 */
1524 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1525
1526 /*
1527 * Speedup sock_wfree()
1528 */
1529 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1530 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1531 }
1532 return register_pernet_subsys(&icmp_sk_ops);
1533}