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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
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 enum skb_drop_reason (*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
195static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk);
196
197/* Called with BH disabled */
198static inline struct sock *icmp_xmit_lock(struct net *net)
199{
200 struct sock *sk;
201
202 sk = this_cpu_read(ipv4_icmp_sk);
203
204 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
205 /* This can happen if the output path signals a
206 * dst_link_failure() for an outgoing ICMP packet.
207 */
208 return NULL;
209 }
210 sock_net_set(sk, net);
211 return sk;
212}
213
214static inline void icmp_xmit_unlock(struct sock *sk)
215{
216 sock_net_set(sk, &init_net);
217 spin_unlock(&sk->sk_lock.slock);
218}
219
220int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
221int sysctl_icmp_msgs_burst __read_mostly = 50;
222
223static struct {
224 spinlock_t lock;
225 u32 credit;
226 u32 stamp;
227} icmp_global = {
228 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
229};
230
231/**
232 * icmp_global_allow - Are we allowed to send one more ICMP message ?
233 *
234 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
235 * Returns false if we reached the limit and can not send another packet.
236 * Note: called with BH disabled
237 */
238bool icmp_global_allow(void)
239{
240 u32 credit, delta, incr = 0, now = (u32)jiffies;
241 bool rc = false;
242
243 /* Check if token bucket is empty and cannot be refilled
244 * without taking the spinlock. The READ_ONCE() are paired
245 * with the following WRITE_ONCE() in this same function.
246 */
247 if (!READ_ONCE(icmp_global.credit)) {
248 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
249 if (delta < HZ / 50)
250 return false;
251 }
252
253 spin_lock(&icmp_global.lock);
254 delta = min_t(u32, now - icmp_global.stamp, HZ);
255 if (delta >= HZ / 50) {
256 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
257 if (incr)
258 WRITE_ONCE(icmp_global.stamp, now);
259 }
260 credit = min_t(u32, icmp_global.credit + incr,
261 READ_ONCE(sysctl_icmp_msgs_burst));
262 if (credit) {
263 /* We want to use a credit of one in average, but need to randomize
264 * it for security reasons.
265 */
266 credit = max_t(int, credit - get_random_u32_below(3), 0);
267 rc = true;
268 }
269 WRITE_ONCE(icmp_global.credit, credit);
270 spin_unlock(&icmp_global.lock);
271 return rc;
272}
273EXPORT_SYMBOL(icmp_global_allow);
274
275static bool icmpv4_mask_allow(struct net *net, int type, int code)
276{
277 if (type > NR_ICMP_TYPES)
278 return true;
279
280 /* Don't limit PMTU discovery. */
281 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
282 return true;
283
284 /* Limit if icmp type is enabled in ratemask. */
285 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
286 return true;
287
288 return false;
289}
290
291static bool icmpv4_global_allow(struct net *net, int type, int code)
292{
293 if (icmpv4_mask_allow(net, type, code))
294 return true;
295
296 if (icmp_global_allow())
297 return true;
298
299 return false;
300}
301
302/*
303 * Send an ICMP frame.
304 */
305
306static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
307 struct flowi4 *fl4, int type, int code)
308{
309 struct dst_entry *dst = &rt->dst;
310 struct inet_peer *peer;
311 bool rc = true;
312 int vif;
313
314 if (icmpv4_mask_allow(net, type, code))
315 goto out;
316
317 /* No rate limit on loopback */
318 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
319 goto out;
320
321 vif = l3mdev_master_ifindex(dst->dev);
322 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
323 rc = inet_peer_xrlim_allow(peer,
324 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
325 if (peer)
326 inet_putpeer(peer);
327out:
328 return rc;
329}
330
331/*
332 * Maintain the counters used in the SNMP statistics for outgoing ICMP
333 */
334void icmp_out_count(struct net *net, unsigned char type)
335{
336 ICMPMSGOUT_INC_STATS(net, type);
337 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
338}
339
340/*
341 * Checksum each fragment, and on the first include the headers and final
342 * checksum.
343 */
344static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
345 struct sk_buff *skb)
346{
347 struct icmp_bxm *icmp_param = from;
348 __wsum csum;
349
350 csum = skb_copy_and_csum_bits(icmp_param->skb,
351 icmp_param->offset + offset,
352 to, len);
353
354 skb->csum = csum_block_add(skb->csum, csum, odd);
355 if (icmp_pointers[icmp_param->data.icmph.type].error)
356 nf_ct_attach(skb, icmp_param->skb);
357 return 0;
358}
359
360static void icmp_push_reply(struct sock *sk,
361 struct icmp_bxm *icmp_param,
362 struct flowi4 *fl4,
363 struct ipcm_cookie *ipc, struct rtable **rt)
364{
365 struct sk_buff *skb;
366
367 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
368 icmp_param->data_len+icmp_param->head_len,
369 icmp_param->head_len,
370 ipc, rt, MSG_DONTWAIT) < 0) {
371 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
372 ip_flush_pending_frames(sk);
373 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
374 struct icmphdr *icmph = icmp_hdr(skb);
375 __wsum csum;
376 struct sk_buff *skb1;
377
378 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
379 (char *)icmph,
380 icmp_param->head_len);
381 skb_queue_walk(&sk->sk_write_queue, skb1) {
382 csum = csum_add(csum, skb1->csum);
383 }
384 icmph->checksum = csum_fold(csum);
385 skb->ip_summed = CHECKSUM_NONE;
386 ip_push_pending_frames(sk, fl4);
387 }
388}
389
390/*
391 * Driving logic for building and sending ICMP messages.
392 */
393
394static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
395{
396 struct ipcm_cookie ipc;
397 struct rtable *rt = skb_rtable(skb);
398 struct net *net = dev_net(rt->dst.dev);
399 struct flowi4 fl4;
400 struct sock *sk;
401 struct inet_sock *inet;
402 __be32 daddr, saddr;
403 u32 mark = IP4_REPLY_MARK(net, skb->mark);
404 int type = icmp_param->data.icmph.type;
405 int code = icmp_param->data.icmph.code;
406
407 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
408 return;
409
410 /* Needed by both icmp_global_allow and icmp_xmit_lock */
411 local_bh_disable();
412
413 /* global icmp_msgs_per_sec */
414 if (!icmpv4_global_allow(net, type, code))
415 goto out_bh_enable;
416
417 sk = icmp_xmit_lock(net);
418 if (!sk)
419 goto out_bh_enable;
420 inet = inet_sk(sk);
421
422 icmp_param->data.icmph.checksum = 0;
423
424 ipcm_init(&ipc);
425 inet->tos = ip_hdr(skb)->tos;
426 ipc.sockc.mark = mark;
427 daddr = ipc.addr = ip_hdr(skb)->saddr;
428 saddr = fib_compute_spec_dst(skb);
429
430 if (icmp_param->replyopts.opt.opt.optlen) {
431 ipc.opt = &icmp_param->replyopts.opt;
432 if (ipc.opt->opt.srr)
433 daddr = icmp_param->replyopts.opt.opt.faddr;
434 }
435 memset(&fl4, 0, sizeof(fl4));
436 fl4.daddr = daddr;
437 fl4.saddr = saddr;
438 fl4.flowi4_mark = mark;
439 fl4.flowi4_uid = sock_net_uid(net, NULL);
440 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
441 fl4.flowi4_proto = IPPROTO_ICMP;
442 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
443 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
444 rt = ip_route_output_key(net, &fl4);
445 if (IS_ERR(rt))
446 goto out_unlock;
447 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
448 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
449 ip_rt_put(rt);
450out_unlock:
451 icmp_xmit_unlock(sk);
452out_bh_enable:
453 local_bh_enable();
454}
455
456/*
457 * The device used for looking up which routing table to use for sending an ICMP
458 * error is preferably the source whenever it is set, which should ensure the
459 * icmp error can be sent to the source host, else lookup using the routing
460 * table of the destination device, else use the main routing table (index 0).
461 */
462static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
463{
464 struct net_device *route_lookup_dev = NULL;
465
466 if (skb->dev)
467 route_lookup_dev = skb->dev;
468 else if (skb_dst(skb))
469 route_lookup_dev = skb_dst(skb)->dev;
470 return route_lookup_dev;
471}
472
473static struct rtable *icmp_route_lookup(struct net *net,
474 struct flowi4 *fl4,
475 struct sk_buff *skb_in,
476 const struct iphdr *iph,
477 __be32 saddr, u8 tos, u32 mark,
478 int type, int code,
479 struct icmp_bxm *param)
480{
481 struct net_device *route_lookup_dev;
482 struct rtable *rt, *rt2;
483 struct flowi4 fl4_dec;
484 int err;
485
486 memset(fl4, 0, sizeof(*fl4));
487 fl4->daddr = (param->replyopts.opt.opt.srr ?
488 param->replyopts.opt.opt.faddr : iph->saddr);
489 fl4->saddr = saddr;
490 fl4->flowi4_mark = mark;
491 fl4->flowi4_uid = sock_net_uid(net, NULL);
492 fl4->flowi4_tos = RT_TOS(tos);
493 fl4->flowi4_proto = IPPROTO_ICMP;
494 fl4->fl4_icmp_type = type;
495 fl4->fl4_icmp_code = code;
496 route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
497 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
498
499 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
500 rt = ip_route_output_key_hash(net, fl4, skb_in);
501 if (IS_ERR(rt))
502 return rt;
503
504 /* No need to clone since we're just using its address. */
505 rt2 = rt;
506
507 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
508 flowi4_to_flowi(fl4), NULL, 0);
509 if (!IS_ERR(rt)) {
510 if (rt != rt2)
511 return rt;
512 } else if (PTR_ERR(rt) == -EPERM) {
513 rt = NULL;
514 } else
515 return rt;
516
517 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
518 if (err)
519 goto relookup_failed;
520
521 if (inet_addr_type_dev_table(net, route_lookup_dev,
522 fl4_dec.saddr) == RTN_LOCAL) {
523 rt2 = __ip_route_output_key(net, &fl4_dec);
524 if (IS_ERR(rt2))
525 err = PTR_ERR(rt2);
526 } else {
527 struct flowi4 fl4_2 = {};
528 unsigned long orefdst;
529
530 fl4_2.daddr = fl4_dec.saddr;
531 rt2 = ip_route_output_key(net, &fl4_2);
532 if (IS_ERR(rt2)) {
533 err = PTR_ERR(rt2);
534 goto relookup_failed;
535 }
536 /* Ugh! */
537 orefdst = skb_in->_skb_refdst; /* save old refdst */
538 skb_dst_set(skb_in, NULL);
539 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
540 RT_TOS(tos), rt2->dst.dev);
541
542 dst_release(&rt2->dst);
543 rt2 = skb_rtable(skb_in);
544 skb_in->_skb_refdst = orefdst; /* restore old refdst */
545 }
546
547 if (err)
548 goto relookup_failed;
549
550 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
551 flowi4_to_flowi(&fl4_dec), NULL,
552 XFRM_LOOKUP_ICMP);
553 if (!IS_ERR(rt2)) {
554 dst_release(&rt->dst);
555 memcpy(fl4, &fl4_dec, sizeof(*fl4));
556 rt = rt2;
557 } else if (PTR_ERR(rt2) == -EPERM) {
558 if (rt)
559 dst_release(&rt->dst);
560 return rt2;
561 } else {
562 err = PTR_ERR(rt2);
563 goto relookup_failed;
564 }
565 return rt;
566
567relookup_failed:
568 if (rt)
569 return rt;
570 return ERR_PTR(err);
571}
572
573/*
574 * Send an ICMP message in response to a situation
575 *
576 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
577 * MAY send more (we do).
578 * MUST NOT change this header information.
579 * MUST NOT reply to a multicast/broadcast IP address.
580 * MUST NOT reply to a multicast/broadcast MAC address.
581 * MUST reply to only the first fragment.
582 */
583
584void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
585 const struct ip_options *opt)
586{
587 struct iphdr *iph;
588 int room;
589 struct icmp_bxm icmp_param;
590 struct rtable *rt = skb_rtable(skb_in);
591 struct ipcm_cookie ipc;
592 struct flowi4 fl4;
593 __be32 saddr;
594 u8 tos;
595 u32 mark;
596 struct net *net;
597 struct sock *sk;
598
599 if (!rt)
600 goto out;
601
602 if (rt->dst.dev)
603 net = dev_net(rt->dst.dev);
604 else if (skb_in->dev)
605 net = dev_net(skb_in->dev);
606 else
607 goto out;
608
609 /*
610 * Find the original header. It is expected to be valid, of course.
611 * Check this, icmp_send is called from the most obscure devices
612 * sometimes.
613 */
614 iph = ip_hdr(skb_in);
615
616 if ((u8 *)iph < skb_in->head ||
617 (skb_network_header(skb_in) + sizeof(*iph)) >
618 skb_tail_pointer(skb_in))
619 goto out;
620
621 /*
622 * No replies to physical multicast/broadcast
623 */
624 if (skb_in->pkt_type != PACKET_HOST)
625 goto out;
626
627 /*
628 * Now check at the protocol level
629 */
630 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
631 goto out;
632
633 /*
634 * Only reply to fragment 0. We byte re-order the constant
635 * mask for efficiency.
636 */
637 if (iph->frag_off & htons(IP_OFFSET))
638 goto out;
639
640 /*
641 * If we send an ICMP error to an ICMP error a mess would result..
642 */
643 if (icmp_pointers[type].error) {
644 /*
645 * We are an error, check if we are replying to an
646 * ICMP error
647 */
648 if (iph->protocol == IPPROTO_ICMP) {
649 u8 _inner_type, *itp;
650
651 itp = skb_header_pointer(skb_in,
652 skb_network_header(skb_in) +
653 (iph->ihl << 2) +
654 offsetof(struct icmphdr,
655 type) -
656 skb_in->data,
657 sizeof(_inner_type),
658 &_inner_type);
659 if (!itp)
660 goto out;
661
662 /*
663 * Assume any unknown ICMP type is an error. This
664 * isn't specified by the RFC, but think about it..
665 */
666 if (*itp > NR_ICMP_TYPES ||
667 icmp_pointers[*itp].error)
668 goto out;
669 }
670 }
671
672 /* Needed by both icmp_global_allow and icmp_xmit_lock */
673 local_bh_disable();
674
675 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
676 * incoming dev is loopback. If outgoing dev change to not be
677 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
678 */
679 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
680 !icmpv4_global_allow(net, type, code))
681 goto out_bh_enable;
682
683 sk = icmp_xmit_lock(net);
684 if (!sk)
685 goto out_bh_enable;
686
687 /*
688 * Construct source address and options.
689 */
690
691 saddr = iph->daddr;
692 if (!(rt->rt_flags & RTCF_LOCAL)) {
693 struct net_device *dev = NULL;
694
695 rcu_read_lock();
696 if (rt_is_input_route(rt) &&
697 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
698 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
699
700 if (dev)
701 saddr = inet_select_addr(dev, iph->saddr,
702 RT_SCOPE_LINK);
703 else
704 saddr = 0;
705 rcu_read_unlock();
706 }
707
708 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
709 IPTOS_PREC_INTERNETCONTROL) :
710 iph->tos;
711 mark = IP4_REPLY_MARK(net, skb_in->mark);
712
713 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
714 goto out_unlock;
715
716
717 /*
718 * Prepare data for ICMP header.
719 */
720
721 icmp_param.data.icmph.type = type;
722 icmp_param.data.icmph.code = code;
723 icmp_param.data.icmph.un.gateway = info;
724 icmp_param.data.icmph.checksum = 0;
725 icmp_param.skb = skb_in;
726 icmp_param.offset = skb_network_offset(skb_in);
727 inet_sk(sk)->tos = tos;
728 ipcm_init(&ipc);
729 ipc.addr = iph->saddr;
730 ipc.opt = &icmp_param.replyopts.opt;
731 ipc.sockc.mark = mark;
732
733 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
734 type, code, &icmp_param);
735 if (IS_ERR(rt))
736 goto out_unlock;
737
738 /* peer icmp_ratelimit */
739 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
740 goto ende;
741
742 /* RFC says return as much as we can without exceeding 576 bytes. */
743
744 room = dst_mtu(&rt->dst);
745 if (room > 576)
746 room = 576;
747 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
748 room -= sizeof(struct icmphdr);
749
750 icmp_param.data_len = skb_in->len - icmp_param.offset;
751 if (icmp_param.data_len > room)
752 icmp_param.data_len = room;
753 icmp_param.head_len = sizeof(struct icmphdr);
754
755 /* if we don't have a source address at this point, fall back to the
756 * dummy address instead of sending out a packet with a source address
757 * of 0.0.0.0
758 */
759 if (!fl4.saddr)
760 fl4.saddr = htonl(INADDR_DUMMY);
761
762 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
763ende:
764 ip_rt_put(rt);
765out_unlock:
766 icmp_xmit_unlock(sk);
767out_bh_enable:
768 local_bh_enable();
769out:;
770}
771EXPORT_SYMBOL(__icmp_send);
772
773#if IS_ENABLED(CONFIG_NF_NAT)
774#include <net/netfilter/nf_conntrack.h>
775void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
776{
777 struct sk_buff *cloned_skb = NULL;
778 struct ip_options opts = { 0 };
779 enum ip_conntrack_info ctinfo;
780 struct nf_conn *ct;
781 __be32 orig_ip;
782
783 ct = nf_ct_get(skb_in, &ctinfo);
784 if (!ct || !(ct->status & IPS_SRC_NAT)) {
785 __icmp_send(skb_in, type, code, info, &opts);
786 return;
787 }
788
789 if (skb_shared(skb_in))
790 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
791
792 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
793 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
794 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
795 skb_network_offset(skb_in) + sizeof(struct iphdr))))
796 goto out;
797
798 orig_ip = ip_hdr(skb_in)->saddr;
799 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
800 __icmp_send(skb_in, type, code, info, &opts);
801 ip_hdr(skb_in)->saddr = orig_ip;
802out:
803 consume_skb(cloned_skb);
804}
805EXPORT_SYMBOL(icmp_ndo_send);
806#endif
807
808static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
809{
810 const struct iphdr *iph = (const struct iphdr *)skb->data;
811 const struct net_protocol *ipprot;
812 int protocol = iph->protocol;
813
814 /* Checkin full IP header plus 8 bytes of protocol to
815 * avoid additional coding at protocol handlers.
816 */
817 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
818 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
819 return;
820 }
821
822 raw_icmp_error(skb, protocol, info);
823
824 ipprot = rcu_dereference(inet_protos[protocol]);
825 if (ipprot && ipprot->err_handler)
826 ipprot->err_handler(skb, info);
827}
828
829static bool icmp_tag_validation(int proto)
830{
831 bool ok;
832
833 rcu_read_lock();
834 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
835 rcu_read_unlock();
836 return ok;
837}
838
839/*
840 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
841 * ICMP_PARAMETERPROB.
842 */
843
844static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
845{
846 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
847 const struct iphdr *iph;
848 struct icmphdr *icmph;
849 struct net *net;
850 u32 info = 0;
851
852 net = dev_net(skb_dst(skb)->dev);
853
854 /*
855 * Incomplete header ?
856 * Only checks for the IP header, there should be an
857 * additional check for longer headers in upper levels.
858 */
859
860 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
861 goto out_err;
862
863 icmph = icmp_hdr(skb);
864 iph = (const struct iphdr *)skb->data;
865
866 if (iph->ihl < 5) { /* Mangled header, drop. */
867 reason = SKB_DROP_REASON_IP_INHDR;
868 goto out_err;
869 }
870
871 switch (icmph->type) {
872 case ICMP_DEST_UNREACH:
873 switch (icmph->code & 15) {
874 case ICMP_NET_UNREACH:
875 case ICMP_HOST_UNREACH:
876 case ICMP_PROT_UNREACH:
877 case ICMP_PORT_UNREACH:
878 break;
879 case ICMP_FRAG_NEEDED:
880 /* for documentation of the ip_no_pmtu_disc
881 * values please see
882 * Documentation/networking/ip-sysctl.rst
883 */
884 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
885 default:
886 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
887 &iph->daddr);
888 break;
889 case 2:
890 goto out;
891 case 3:
892 if (!icmp_tag_validation(iph->protocol))
893 goto out;
894 fallthrough;
895 case 0:
896 info = ntohs(icmph->un.frag.mtu);
897 }
898 break;
899 case ICMP_SR_FAILED:
900 net_dbg_ratelimited("%pI4: Source Route Failed\n",
901 &iph->daddr);
902 break;
903 default:
904 break;
905 }
906 if (icmph->code > NR_ICMP_UNREACH)
907 goto out;
908 break;
909 case ICMP_PARAMETERPROB:
910 info = ntohl(icmph->un.gateway) >> 24;
911 break;
912 case ICMP_TIME_EXCEEDED:
913 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
914 if (icmph->code == ICMP_EXC_FRAGTIME)
915 goto out;
916 break;
917 }
918
919 /*
920 * Throw it at our lower layers
921 *
922 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
923 * header.
924 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
925 * transport layer.
926 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
927 * transport layer.
928 */
929
930 /*
931 * Check the other end isn't violating RFC 1122. Some routers send
932 * bogus responses to broadcast frames. If you see this message
933 * first check your netmask matches at both ends, if it does then
934 * get the other vendor to fix their kit.
935 */
936
937 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
938 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
939 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
940 &ip_hdr(skb)->saddr,
941 icmph->type, icmph->code,
942 &iph->daddr, skb->dev->name);
943 goto out;
944 }
945
946 icmp_socket_deliver(skb, info);
947
948out:
949 return reason;
950out_err:
951 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
952 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
953}
954
955
956/*
957 * Handle ICMP_REDIRECT.
958 */
959
960static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
961{
962 if (skb->len < sizeof(struct iphdr)) {
963 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
964 return SKB_DROP_REASON_PKT_TOO_SMALL;
965 }
966
967 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
968 /* there aught to be a stat */
969 return SKB_DROP_REASON_NOMEM;
970 }
971
972 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
973 return SKB_NOT_DROPPED_YET;
974}
975
976/*
977 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
978 *
979 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
980 * requests.
981 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
982 * included in the reply.
983 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
984 * echo requests, MUST have default=NOT.
985 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
986 * Extended Echo Functionality, MUST be disabled by default
987 * See also WRT handling of options once they are done and working.
988 */
989
990static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
991{
992 struct icmp_bxm icmp_param;
993 struct net *net;
994
995 net = dev_net(skb_dst(skb)->dev);
996 /* should there be an ICMP stat for ignored echos? */
997 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
998 return SKB_NOT_DROPPED_YET;
999
1000 icmp_param.data.icmph = *icmp_hdr(skb);
1001 icmp_param.skb = skb;
1002 icmp_param.offset = 0;
1003 icmp_param.data_len = skb->len;
1004 icmp_param.head_len = sizeof(struct icmphdr);
1005
1006 if (icmp_param.data.icmph.type == ICMP_ECHO)
1007 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1008 else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1009 return SKB_NOT_DROPPED_YET;
1010
1011 icmp_reply(&icmp_param, skb);
1012 return SKB_NOT_DROPPED_YET;
1013}
1014
1015/* Helper for icmp_echo and icmpv6_echo_reply.
1016 * Searches for net_device that matches PROBE interface identifier
1017 * and builds PROBE reply message in icmphdr.
1018 *
1019 * Returns false if PROBE responses are disabled via sysctl
1020 */
1021
1022bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1023{
1024 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1025 struct icmp_ext_echo_iio *iio, _iio;
1026 struct net *net = dev_net(skb->dev);
1027 struct net_device *dev;
1028 char buff[IFNAMSIZ];
1029 u16 ident_len;
1030 u8 status;
1031
1032 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1033 return false;
1034
1035 /* We currently only support probing interfaces on the proxy node
1036 * Check to ensure L-bit is set
1037 */
1038 if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1039 return false;
1040 /* Clear status bits in reply message */
1041 icmphdr->un.echo.sequence &= htons(0xFF00);
1042 if (icmphdr->type == ICMP_EXT_ECHO)
1043 icmphdr->type = ICMP_EXT_ECHOREPLY;
1044 else
1045 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1046 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1047 /* Size of iio is class_type dependent.
1048 * Only check header here and assign length based on ctype in the switch statement
1049 */
1050 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1051 if (!ext_hdr || !iio)
1052 goto send_mal_query;
1053 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1054 ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1055 goto send_mal_query;
1056 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1057 iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1058 sizeof(iio->extobj_hdr) + ident_len, &_iio);
1059 if (!iio)
1060 goto send_mal_query;
1061
1062 status = 0;
1063 dev = NULL;
1064 switch (iio->extobj_hdr.class_type) {
1065 case ICMP_EXT_ECHO_CTYPE_NAME:
1066 if (ident_len >= IFNAMSIZ)
1067 goto send_mal_query;
1068 memset(buff, 0, sizeof(buff));
1069 memcpy(buff, &iio->ident.name, ident_len);
1070 dev = dev_get_by_name(net, buff);
1071 break;
1072 case ICMP_EXT_ECHO_CTYPE_INDEX:
1073 if (ident_len != sizeof(iio->ident.ifindex))
1074 goto send_mal_query;
1075 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1076 break;
1077 case ICMP_EXT_ECHO_CTYPE_ADDR:
1078 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1079 ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1080 iio->ident.addr.ctype3_hdr.addrlen)
1081 goto send_mal_query;
1082 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1083 case ICMP_AFI_IP:
1084 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1085 goto send_mal_query;
1086 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1087 break;
1088#if IS_ENABLED(CONFIG_IPV6)
1089 case ICMP_AFI_IP6:
1090 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1091 goto send_mal_query;
1092 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1093 dev_hold(dev);
1094 break;
1095#endif
1096 default:
1097 goto send_mal_query;
1098 }
1099 break;
1100 default:
1101 goto send_mal_query;
1102 }
1103 if (!dev) {
1104 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1105 return true;
1106 }
1107 /* Fill bits in reply message */
1108 if (dev->flags & IFF_UP)
1109 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1110 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1111 status |= ICMP_EXT_ECHOREPLY_IPV4;
1112 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1113 status |= ICMP_EXT_ECHOREPLY_IPV6;
1114 dev_put(dev);
1115 icmphdr->un.echo.sequence |= htons(status);
1116 return true;
1117send_mal_query:
1118 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1119 return true;
1120}
1121EXPORT_SYMBOL_GPL(icmp_build_probe);
1122
1123/*
1124 * Handle ICMP Timestamp requests.
1125 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1126 * SHOULD be in the kernel for minimum random latency.
1127 * MUST be accurate to a few minutes.
1128 * MUST be updated at least at 15Hz.
1129 */
1130static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1131{
1132 struct icmp_bxm icmp_param;
1133 /*
1134 * Too short.
1135 */
1136 if (skb->len < 4)
1137 goto out_err;
1138
1139 /*
1140 * Fill in the current time as ms since midnight UT:
1141 */
1142 icmp_param.data.times[1] = inet_current_timestamp();
1143 icmp_param.data.times[2] = icmp_param.data.times[1];
1144
1145 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1146
1147 icmp_param.data.icmph = *icmp_hdr(skb);
1148 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1149 icmp_param.data.icmph.code = 0;
1150 icmp_param.skb = skb;
1151 icmp_param.offset = 0;
1152 icmp_param.data_len = 0;
1153 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1154 icmp_reply(&icmp_param, skb);
1155 return SKB_NOT_DROPPED_YET;
1156
1157out_err:
1158 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1159 return SKB_DROP_REASON_PKT_TOO_SMALL;
1160}
1161
1162static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1163{
1164 /* pretend it was a success */
1165 return SKB_NOT_DROPPED_YET;
1166}
1167
1168/*
1169 * Deal with incoming ICMP packets.
1170 */
1171int icmp_rcv(struct sk_buff *skb)
1172{
1173 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1174 struct rtable *rt = skb_rtable(skb);
1175 struct net *net = dev_net(rt->dst.dev);
1176 struct icmphdr *icmph;
1177
1178 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1179 struct sec_path *sp = skb_sec_path(skb);
1180 int nh;
1181
1182 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1183 XFRM_STATE_ICMP)) {
1184 reason = SKB_DROP_REASON_XFRM_POLICY;
1185 goto drop;
1186 }
1187
1188 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1189 goto drop;
1190
1191 nh = skb_network_offset(skb);
1192 skb_set_network_header(skb, sizeof(*icmph));
1193
1194 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1195 skb)) {
1196 reason = SKB_DROP_REASON_XFRM_POLICY;
1197 goto drop;
1198 }
1199
1200 skb_set_network_header(skb, nh);
1201 }
1202
1203 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1204
1205 if (skb_checksum_simple_validate(skb))
1206 goto csum_error;
1207
1208 if (!pskb_pull(skb, sizeof(*icmph)))
1209 goto error;
1210
1211 icmph = icmp_hdr(skb);
1212
1213 ICMPMSGIN_INC_STATS(net, icmph->type);
1214
1215 /* Check for ICMP Extended Echo (PROBE) messages */
1216 if (icmph->type == ICMP_EXT_ECHO) {
1217 /* We can't use icmp_pointers[].handler() because it is an array of
1218 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1219 */
1220 reason = icmp_echo(skb);
1221 goto reason_check;
1222 }
1223
1224 if (icmph->type == ICMP_EXT_ECHOREPLY) {
1225 reason = ping_rcv(skb);
1226 goto reason_check;
1227 }
1228
1229 /*
1230 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1231 *
1232 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1233 * discarded.
1234 */
1235 if (icmph->type > NR_ICMP_TYPES) {
1236 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1237 goto error;
1238 }
1239
1240 /*
1241 * Parse the ICMP message
1242 */
1243
1244 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1245 /*
1246 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1247 * silently ignored (we let user decide with a sysctl).
1248 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1249 * discarded if to broadcast/multicast.
1250 */
1251 if ((icmph->type == ICMP_ECHO ||
1252 icmph->type == ICMP_TIMESTAMP) &&
1253 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1254 reason = SKB_DROP_REASON_INVALID_PROTO;
1255 goto error;
1256 }
1257 if (icmph->type != ICMP_ECHO &&
1258 icmph->type != ICMP_TIMESTAMP &&
1259 icmph->type != ICMP_ADDRESS &&
1260 icmph->type != ICMP_ADDRESSREPLY) {
1261 reason = SKB_DROP_REASON_INVALID_PROTO;
1262 goto error;
1263 }
1264 }
1265
1266 reason = icmp_pointers[icmph->type].handler(skb);
1267reason_check:
1268 if (!reason) {
1269 consume_skb(skb);
1270 return NET_RX_SUCCESS;
1271 }
1272
1273drop:
1274 kfree_skb_reason(skb, reason);
1275 return NET_RX_DROP;
1276csum_error:
1277 reason = SKB_DROP_REASON_ICMP_CSUM;
1278 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1279error:
1280 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1281 goto drop;
1282}
1283
1284static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1285{
1286 struct icmp_extobj_hdr *objh, _objh;
1287 struct icmp_ext_hdr *exth, _exth;
1288 u16 olen;
1289
1290 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1291 if (!exth)
1292 return false;
1293 if (exth->version != 2)
1294 return true;
1295
1296 if (exth->checksum &&
1297 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1298 return false;
1299
1300 off += sizeof(_exth);
1301 while (off < skb->len) {
1302 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1303 if (!objh)
1304 return false;
1305
1306 olen = ntohs(objh->length);
1307 if (olen < sizeof(_objh))
1308 return false;
1309
1310 off += olen;
1311 if (off > skb->len)
1312 return false;
1313 }
1314
1315 return true;
1316}
1317
1318void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1319 struct sock_ee_data_rfc4884 *out,
1320 int thlen, int off)
1321{
1322 int hlen;
1323
1324 /* original datagram headers: end of icmph to payload (skb->data) */
1325 hlen = -skb_transport_offset(skb) - thlen;
1326
1327 /* per rfc 4884: minimal datagram length of 128 bytes */
1328 if (off < 128 || off < hlen)
1329 return;
1330
1331 /* kernel has stripped headers: return payload offset in bytes */
1332 off -= hlen;
1333 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1334 return;
1335
1336 out->len = off;
1337
1338 if (!ip_icmp_error_rfc4884_validate(skb, off))
1339 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1340}
1341EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1342
1343int icmp_err(struct sk_buff *skb, u32 info)
1344{
1345 struct iphdr *iph = (struct iphdr *)skb->data;
1346 int offset = iph->ihl<<2;
1347 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1348 int type = icmp_hdr(skb)->type;
1349 int code = icmp_hdr(skb)->code;
1350 struct net *net = dev_net(skb->dev);
1351
1352 /*
1353 * Use ping_err to handle all icmp errors except those
1354 * triggered by ICMP_ECHOREPLY which sent from kernel.
1355 */
1356 if (icmph->type != ICMP_ECHOREPLY) {
1357 ping_err(skb, offset, info);
1358 return 0;
1359 }
1360
1361 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1362 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1363 else if (type == ICMP_REDIRECT)
1364 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1365
1366 return 0;
1367}
1368
1369/*
1370 * This table is the definition of how we handle ICMP.
1371 */
1372static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1373 [ICMP_ECHOREPLY] = {
1374 .handler = ping_rcv,
1375 },
1376 [1] = {
1377 .handler = icmp_discard,
1378 .error = 1,
1379 },
1380 [2] = {
1381 .handler = icmp_discard,
1382 .error = 1,
1383 },
1384 [ICMP_DEST_UNREACH] = {
1385 .handler = icmp_unreach,
1386 .error = 1,
1387 },
1388 [ICMP_SOURCE_QUENCH] = {
1389 .handler = icmp_unreach,
1390 .error = 1,
1391 },
1392 [ICMP_REDIRECT] = {
1393 .handler = icmp_redirect,
1394 .error = 1,
1395 },
1396 [6] = {
1397 .handler = icmp_discard,
1398 .error = 1,
1399 },
1400 [7] = {
1401 .handler = icmp_discard,
1402 .error = 1,
1403 },
1404 [ICMP_ECHO] = {
1405 .handler = icmp_echo,
1406 },
1407 [9] = {
1408 .handler = icmp_discard,
1409 .error = 1,
1410 },
1411 [10] = {
1412 .handler = icmp_discard,
1413 .error = 1,
1414 },
1415 [ICMP_TIME_EXCEEDED] = {
1416 .handler = icmp_unreach,
1417 .error = 1,
1418 },
1419 [ICMP_PARAMETERPROB] = {
1420 .handler = icmp_unreach,
1421 .error = 1,
1422 },
1423 [ICMP_TIMESTAMP] = {
1424 .handler = icmp_timestamp,
1425 },
1426 [ICMP_TIMESTAMPREPLY] = {
1427 .handler = icmp_discard,
1428 },
1429 [ICMP_INFO_REQUEST] = {
1430 .handler = icmp_discard,
1431 },
1432 [ICMP_INFO_REPLY] = {
1433 .handler = icmp_discard,
1434 },
1435 [ICMP_ADDRESS] = {
1436 .handler = icmp_discard,
1437 },
1438 [ICMP_ADDRESSREPLY] = {
1439 .handler = icmp_discard,
1440 },
1441};
1442
1443static int __net_init icmp_sk_init(struct net *net)
1444{
1445 /* Control parameters for ECHO replies. */
1446 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1447 net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1448 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1449
1450 /* Control parameter - ignore bogus broadcast responses? */
1451 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1452
1453 /*
1454 * Configurable global rate limit.
1455 *
1456 * ratelimit defines tokens/packet consumed for dst->rate_token
1457 * bucket ratemask defines which icmp types are ratelimited by
1458 * setting it's bit position.
1459 *
1460 * default:
1461 * dest unreachable (3), source quench (4),
1462 * time exceeded (11), parameter problem (12)
1463 */
1464
1465 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1466 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1467 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1468
1469 return 0;
1470}
1471
1472static struct pernet_operations __net_initdata icmp_sk_ops = {
1473 .init = icmp_sk_init,
1474};
1475
1476int __init icmp_init(void)
1477{
1478 int err, i;
1479
1480 for_each_possible_cpu(i) {
1481 struct sock *sk;
1482
1483 err = inet_ctl_sock_create(&sk, PF_INET,
1484 SOCK_RAW, IPPROTO_ICMP, &init_net);
1485 if (err < 0)
1486 return err;
1487
1488 per_cpu(ipv4_icmp_sk, i) = sk;
1489
1490 /* Enough space for 2 64K ICMP packets, including
1491 * sk_buff/skb_shared_info struct overhead.
1492 */
1493 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1494
1495 /*
1496 * Speedup sock_wfree()
1497 */
1498 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1499 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1500 }
1501 return register_pernet_subsys(&icmp_sk_ops);
1502}