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