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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * NET3: Implementation of the ICMP protocol layer.
4 *
5 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
6 *
7 * Some of the function names and the icmp unreach table for this
8 * module were derived from [icmp.c 1.0.11 06/02/93] by
9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
10 * Other than that this module is a complete rewrite.
11 *
12 * Fixes:
13 * Clemens Fruhwirth : introduce global icmp rate limiting
14 * with icmp type masking ability instead
15 * of broken per type icmp timeouts.
16 * Mike Shaver : RFC1122 checks.
17 * Alan Cox : Multicast ping reply as self.
18 * Alan Cox : Fix atomicity lockup in ip_build_xmit
19 * call.
20 * Alan Cox : Added 216,128 byte paths to the MTU
21 * code.
22 * Martin Mares : RFC1812 checks.
23 * Martin Mares : Can be configured to follow redirects
24 * if acting as a router _without_ a
25 * routing protocol (RFC 1812).
26 * Martin Mares : Echo requests may be configured to
27 * be ignored (RFC 1812).
28 * Martin Mares : Limitation of ICMP error message
29 * transmit rate (RFC 1812).
30 * Martin Mares : TOS and Precedence set correctly
31 * (RFC 1812).
32 * Martin Mares : Now copying as much data from the
33 * original packet as we can without
34 * exceeding 576 bytes (RFC 1812).
35 * Willy Konynenberg : Transparent proxying support.
36 * Keith Owens : RFC1191 correction for 4.2BSD based
37 * path MTU bug.
38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
39 * valid (RFC 1812).
40 * Andi Kleen : Check all packet lengths properly
41 * and moved all kfree_skb() up to
42 * icmp_rcv.
43 * Andi Kleen : Move the rate limit bookkeeping
44 * into the dest entry and use a token
45 * bucket filter (thanks to ANK). Make
46 * the rates sysctl configurable.
47 * Yu Tianli : Fixed two ugly bugs in icmp_send
48 * - IP option length was accounted wrongly
49 * - ICMP header length was not accounted
50 * at all.
51 * Tristan Greaves : Added sysctl option to ignore bogus
52 * broadcast responses from broken routers.
53 *
54 * To Fix:
55 *
56 * - Should use skb_pull() instead of all the manual checking.
57 * This would also greatly simply some upper layer error handlers. --AK
58 */
59
60#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61
62#include <linux/module.h>
63#include <linux/types.h>
64#include <linux/jiffies.h>
65#include <linux/kernel.h>
66#include <linux/fcntl.h>
67#include <linux/socket.h>
68#include <linux/in.h>
69#include <linux/inet.h>
70#include <linux/inetdevice.h>
71#include <linux/netdevice.h>
72#include <linux/string.h>
73#include <linux/netfilter_ipv4.h>
74#include <linux/slab.h>
75#include <net/snmp.h>
76#include <net/ip.h>
77#include <net/route.h>
78#include <net/protocol.h>
79#include <net/icmp.h>
80#include <net/tcp.h>
81#include <net/udp.h>
82#include <net/raw.h>
83#include <net/ping.h>
84#include <linux/skbuff.h>
85#include <net/sock.h>
86#include <linux/errno.h>
87#include <linux/timer.h>
88#include <linux/init.h>
89#include <linux/uaccess.h>
90#include <net/checksum.h>
91#include <net/xfrm.h>
92#include <net/inet_common.h>
93#include <net/ip_fib.h>
94#include <net/l3mdev.h>
95
96/*
97 * Build xmit assembly blocks
98 */
99
100struct icmp_bxm {
101 struct sk_buff *skb;
102 int offset;
103 int data_len;
104
105 struct {
106 struct icmphdr icmph;
107 __be32 times[3];
108 } data;
109 int head_len;
110 struct ip_options_data replyopts;
111};
112
113/* An array of errno for error messages from dest unreach. */
114/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
115
116const struct icmp_err icmp_err_convert[] = {
117 {
118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
119 .fatal = 0,
120 },
121 {
122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
123 .fatal = 0,
124 },
125 {
126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
127 .fatal = 1,
128 },
129 {
130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
131 .fatal = 1,
132 },
133 {
134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
135 .fatal = 0,
136 },
137 {
138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
139 .fatal = 0,
140 },
141 {
142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
143 .fatal = 1,
144 },
145 {
146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
147 .fatal = 1,
148 },
149 {
150 .errno = ENONET, /* ICMP_HOST_ISOLATED */
151 .fatal = 1,
152 },
153 {
154 .errno = ENETUNREACH, /* ICMP_NET_ANO */
155 .fatal = 1,
156 },
157 {
158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
159 .fatal = 1,
160 },
161 {
162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
163 .fatal = 0,
164 },
165 {
166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
167 .fatal = 0,
168 },
169 {
170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
171 .fatal = 1,
172 },
173 {
174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
175 .fatal = 1,
176 },
177 {
178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
179 .fatal = 1,
180 },
181};
182EXPORT_SYMBOL(icmp_err_convert);
183
184/*
185 * ICMP control array. This specifies what to do with each ICMP.
186 */
187
188struct icmp_control {
189 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 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
300 return false;
301}
302
303/*
304 * Send an ICMP frame.
305 */
306
307static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
308 struct flowi4 *fl4, int type, int code)
309{
310 struct dst_entry *dst = &rt->dst;
311 struct inet_peer *peer;
312 bool rc = true;
313 int vif;
314
315 if (icmpv4_mask_allow(net, type, code))
316 goto out;
317
318 /* No rate limit on loopback */
319 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
320 goto out;
321
322 vif = l3mdev_master_ifindex(dst->dev);
323 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
324 rc = inet_peer_xrlim_allow(peer,
325 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
326 if (peer)
327 inet_putpeer(peer);
328out:
329 if (!rc)
330 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST);
331 return rc;
332}
333
334/*
335 * Maintain the counters used in the SNMP statistics for outgoing ICMP
336 */
337void icmp_out_count(struct net *net, unsigned char type)
338{
339 ICMPMSGOUT_INC_STATS(net, type);
340 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
341}
342
343/*
344 * Checksum each fragment, and on the first include the headers and final
345 * checksum.
346 */
347static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
348 struct sk_buff *skb)
349{
350 struct icmp_bxm *icmp_param = from;
351 __wsum csum;
352
353 csum = skb_copy_and_csum_bits(icmp_param->skb,
354 icmp_param->offset + offset,
355 to, len);
356
357 skb->csum = csum_block_add(skb->csum, csum, odd);
358 if (icmp_pointers[icmp_param->data.icmph.type].error)
359 nf_ct_attach(skb, icmp_param->skb);
360 return 0;
361}
362
363static void icmp_push_reply(struct sock *sk,
364 struct icmp_bxm *icmp_param,
365 struct flowi4 *fl4,
366 struct ipcm_cookie *ipc, struct rtable **rt)
367{
368 struct sk_buff *skb;
369
370 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
371 icmp_param->data_len+icmp_param->head_len,
372 icmp_param->head_len,
373 ipc, rt, MSG_DONTWAIT) < 0) {
374 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
375 ip_flush_pending_frames(sk);
376 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
377 struct icmphdr *icmph = icmp_hdr(skb);
378 __wsum csum;
379 struct sk_buff *skb1;
380
381 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
382 (char *)icmph,
383 icmp_param->head_len);
384 skb_queue_walk(&sk->sk_write_queue, skb1) {
385 csum = csum_add(csum, skb1->csum);
386 }
387 icmph->checksum = csum_fold(csum);
388 skb->ip_summed = CHECKSUM_NONE;
389 ip_push_pending_frames(sk, fl4);
390 }
391}
392
393/*
394 * Driving logic for building and sending ICMP messages.
395 */
396
397static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
398{
399 struct ipcm_cookie ipc;
400 struct rtable *rt = skb_rtable(skb);
401 struct net *net = dev_net(rt->dst.dev);
402 struct flowi4 fl4;
403 struct sock *sk;
404 struct inet_sock *inet;
405 __be32 daddr, saddr;
406 u32 mark = IP4_REPLY_MARK(net, skb->mark);
407 int type = icmp_param->data.icmph.type;
408 int code = icmp_param->data.icmph.code;
409
410 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
411 return;
412
413 /* Needed by both icmp_global_allow and icmp_xmit_lock */
414 local_bh_disable();
415
416 /* global icmp_msgs_per_sec */
417 if (!icmpv4_global_allow(net, type, code))
418 goto out_bh_enable;
419
420 sk = icmp_xmit_lock(net);
421 if (!sk)
422 goto out_bh_enable;
423 inet = inet_sk(sk);
424
425 icmp_param->data.icmph.checksum = 0;
426
427 ipcm_init(&ipc);
428 inet->tos = ip_hdr(skb)->tos;
429 ipc.sockc.mark = mark;
430 daddr = ipc.addr = ip_hdr(skb)->saddr;
431 saddr = fib_compute_spec_dst(skb);
432
433 if (icmp_param->replyopts.opt.opt.optlen) {
434 ipc.opt = &icmp_param->replyopts.opt;
435 if (ipc.opt->opt.srr)
436 daddr = icmp_param->replyopts.opt.opt.faddr;
437 }
438 memset(&fl4, 0, sizeof(fl4));
439 fl4.daddr = daddr;
440 fl4.saddr = saddr;
441 fl4.flowi4_mark = mark;
442 fl4.flowi4_uid = sock_net_uid(net, NULL);
443 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
444 fl4.flowi4_proto = IPPROTO_ICMP;
445 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
446 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
447 rt = ip_route_output_key(net, &fl4);
448 if (IS_ERR(rt))
449 goto out_unlock;
450 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
451 icmp_push_reply(sk, icmp_param, &fl4, &ipc, &rt);
452 ip_rt_put(rt);
453out_unlock:
454 icmp_xmit_unlock(sk);
455out_bh_enable:
456 local_bh_enable();
457}
458
459/*
460 * The device used for looking up which routing table to use for sending an ICMP
461 * error is preferably the source whenever it is set, which should ensure the
462 * icmp error can be sent to the source host, else lookup using the routing
463 * table of the destination device, else use the main routing table (index 0).
464 */
465static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
466{
467 struct net_device *route_lookup_dev = NULL;
468
469 if (skb->dev)
470 route_lookup_dev = skb->dev;
471 else if (skb_dst(skb))
472 route_lookup_dev = skb_dst(skb)->dev;
473 return route_lookup_dev;
474}
475
476static struct rtable *icmp_route_lookup(struct net *net,
477 struct flowi4 *fl4,
478 struct sk_buff *skb_in,
479 const struct iphdr *iph,
480 __be32 saddr, u8 tos, u32 mark,
481 int type, int code,
482 struct icmp_bxm *param)
483{
484 struct net_device *route_lookup_dev;
485 struct rtable *rt, *rt2;
486 struct flowi4 fl4_dec;
487 int err;
488
489 memset(fl4, 0, sizeof(*fl4));
490 fl4->daddr = (param->replyopts.opt.opt.srr ?
491 param->replyopts.opt.opt.faddr : iph->saddr);
492 fl4->saddr = saddr;
493 fl4->flowi4_mark = mark;
494 fl4->flowi4_uid = sock_net_uid(net, NULL);
495 fl4->flowi4_tos = RT_TOS(tos);
496 fl4->flowi4_proto = IPPROTO_ICMP;
497 fl4->fl4_icmp_type = type;
498 fl4->fl4_icmp_code = code;
499 route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
500 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
501
502 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
503 rt = ip_route_output_key_hash(net, fl4, skb_in);
504 if (IS_ERR(rt))
505 return rt;
506
507 /* No need to clone since we're just using its address. */
508 rt2 = rt;
509
510 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
511 flowi4_to_flowi(fl4), NULL, 0);
512 if (!IS_ERR(rt)) {
513 if (rt != rt2)
514 return rt;
515 } else if (PTR_ERR(rt) == -EPERM) {
516 rt = NULL;
517 } else
518 return rt;
519
520 err = xfrm_decode_session_reverse(net, skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
521 if (err)
522 goto relookup_failed;
523
524 if (inet_addr_type_dev_table(net, route_lookup_dev,
525 fl4_dec.saddr) == RTN_LOCAL) {
526 rt2 = __ip_route_output_key(net, &fl4_dec);
527 if (IS_ERR(rt2))
528 err = PTR_ERR(rt2);
529 } else {
530 struct flowi4 fl4_2 = {};
531 unsigned long orefdst;
532
533 fl4_2.daddr = fl4_dec.saddr;
534 rt2 = ip_route_output_key(net, &fl4_2);
535 if (IS_ERR(rt2)) {
536 err = PTR_ERR(rt2);
537 goto relookup_failed;
538 }
539 /* Ugh! */
540 orefdst = skb_in->_skb_refdst; /* save old refdst */
541 skb_dst_set(skb_in, NULL);
542 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
543 RT_TOS(tos), rt2->dst.dev);
544
545 dst_release(&rt2->dst);
546 rt2 = skb_rtable(skb_in);
547 skb_in->_skb_refdst = orefdst; /* restore old refdst */
548 }
549
550 if (err)
551 goto relookup_failed;
552
553 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
554 flowi4_to_flowi(&fl4_dec), NULL,
555 XFRM_LOOKUP_ICMP);
556 if (!IS_ERR(rt2)) {
557 dst_release(&rt->dst);
558 memcpy(fl4, &fl4_dec, sizeof(*fl4));
559 rt = rt2;
560 } else if (PTR_ERR(rt2) == -EPERM) {
561 if (rt)
562 dst_release(&rt->dst);
563 return rt2;
564 } else {
565 err = PTR_ERR(rt2);
566 goto relookup_failed;
567 }
568 return rt;
569
570relookup_failed:
571 if (rt)
572 return rt;
573 return ERR_PTR(err);
574}
575
576/*
577 * Send an ICMP message in response to a situation
578 *
579 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
580 * MAY send more (we do).
581 * MUST NOT change this header information.
582 * MUST NOT reply to a multicast/broadcast IP address.
583 * MUST NOT reply to a multicast/broadcast MAC address.
584 * MUST reply to only the first fragment.
585 */
586
587void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
588 const struct ip_options *opt)
589{
590 struct iphdr *iph;
591 int room;
592 struct icmp_bxm icmp_param;
593 struct rtable *rt = skb_rtable(skb_in);
594 struct ipcm_cookie ipc;
595 struct flowi4 fl4;
596 __be32 saddr;
597 u8 tos;
598 u32 mark;
599 struct net *net;
600 struct sock *sk;
601
602 if (!rt)
603 goto out;
604
605 if (rt->dst.dev)
606 net = dev_net(rt->dst.dev);
607 else if (skb_in->dev)
608 net = dev_net(skb_in->dev);
609 else
610 goto out;
611
612 /*
613 * Find the original header. It is expected to be valid, of course.
614 * Check this, icmp_send is called from the most obscure devices
615 * sometimes.
616 */
617 iph = ip_hdr(skb_in);
618
619 if ((u8 *)iph < skb_in->head ||
620 (skb_network_header(skb_in) + sizeof(*iph)) >
621 skb_tail_pointer(skb_in))
622 goto out;
623
624 /*
625 * No replies to physical multicast/broadcast
626 */
627 if (skb_in->pkt_type != PACKET_HOST)
628 goto out;
629
630 /*
631 * Now check at the protocol level
632 */
633 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
634 goto out;
635
636 /*
637 * Only reply to fragment 0. We byte re-order the constant
638 * mask for efficiency.
639 */
640 if (iph->frag_off & htons(IP_OFFSET))
641 goto out;
642
643 /*
644 * If we send an ICMP error to an ICMP error a mess would result..
645 */
646 if (icmp_pointers[type].error) {
647 /*
648 * We are an error, check if we are replying to an
649 * ICMP error
650 */
651 if (iph->protocol == IPPROTO_ICMP) {
652 u8 _inner_type, *itp;
653
654 itp = skb_header_pointer(skb_in,
655 skb_network_header(skb_in) +
656 (iph->ihl << 2) +
657 offsetof(struct icmphdr,
658 type) -
659 skb_in->data,
660 sizeof(_inner_type),
661 &_inner_type);
662 if (!itp)
663 goto out;
664
665 /*
666 * Assume any unknown ICMP type is an error. This
667 * isn't specified by the RFC, but think about it..
668 */
669 if (*itp > NR_ICMP_TYPES ||
670 icmp_pointers[*itp].error)
671 goto out;
672 }
673 }
674
675 /* Needed by both icmp_global_allow and icmp_xmit_lock */
676 local_bh_disable();
677
678 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
679 * incoming dev is loopback. If outgoing dev change to not be
680 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
681 */
682 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
683 !icmpv4_global_allow(net, type, code))
684 goto out_bh_enable;
685
686 sk = icmp_xmit_lock(net);
687 if (!sk)
688 goto out_bh_enable;
689
690 /*
691 * Construct source address and options.
692 */
693
694 saddr = iph->daddr;
695 if (!(rt->rt_flags & RTCF_LOCAL)) {
696 struct net_device *dev = NULL;
697
698 rcu_read_lock();
699 if (rt_is_input_route(rt) &&
700 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
701 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
702
703 if (dev)
704 saddr = inet_select_addr(dev, iph->saddr,
705 RT_SCOPE_LINK);
706 else
707 saddr = 0;
708 rcu_read_unlock();
709 }
710
711 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
712 IPTOS_PREC_INTERNETCONTROL) :
713 iph->tos;
714 mark = IP4_REPLY_MARK(net, skb_in->mark);
715
716 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
717 goto out_unlock;
718
719
720 /*
721 * Prepare data for ICMP header.
722 */
723
724 icmp_param.data.icmph.type = type;
725 icmp_param.data.icmph.code = code;
726 icmp_param.data.icmph.un.gateway = info;
727 icmp_param.data.icmph.checksum = 0;
728 icmp_param.skb = skb_in;
729 icmp_param.offset = skb_network_offset(skb_in);
730 inet_sk(sk)->tos = tos;
731 ipcm_init(&ipc);
732 ipc.addr = iph->saddr;
733 ipc.opt = &icmp_param.replyopts.opt;
734 ipc.sockc.mark = mark;
735
736 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
737 type, code, &icmp_param);
738 if (IS_ERR(rt))
739 goto out_unlock;
740
741 /* peer icmp_ratelimit */
742 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
743 goto ende;
744
745 /* RFC says return as much as we can without exceeding 576 bytes. */
746
747 room = dst_mtu(&rt->dst);
748 if (room > 576)
749 room = 576;
750 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
751 room -= sizeof(struct icmphdr);
752 /* Guard against tiny mtu. We need to include at least one
753 * IP network header for this message to make any sense.
754 */
755 if (room <= (int)sizeof(struct iphdr))
756 goto ende;
757
758 icmp_param.data_len = skb_in->len - icmp_param.offset;
759 if (icmp_param.data_len > room)
760 icmp_param.data_len = room;
761 icmp_param.head_len = sizeof(struct icmphdr);
762
763 /* if we don't have a source address at this point, fall back to the
764 * dummy address instead of sending out a packet with a source address
765 * of 0.0.0.0
766 */
767 if (!fl4.saddr)
768 fl4.saddr = htonl(INADDR_DUMMY);
769
770 icmp_push_reply(sk, &icmp_param, &fl4, &ipc, &rt);
771ende:
772 ip_rt_put(rt);
773out_unlock:
774 icmp_xmit_unlock(sk);
775out_bh_enable:
776 local_bh_enable();
777out:;
778}
779EXPORT_SYMBOL(__icmp_send);
780
781#if IS_ENABLED(CONFIG_NF_NAT)
782#include <net/netfilter/nf_conntrack.h>
783void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
784{
785 struct sk_buff *cloned_skb = NULL;
786 struct ip_options opts = { 0 };
787 enum ip_conntrack_info ctinfo;
788 struct nf_conn *ct;
789 __be32 orig_ip;
790
791 ct = nf_ct_get(skb_in, &ctinfo);
792 if (!ct || !(ct->status & IPS_SRC_NAT)) {
793 __icmp_send(skb_in, type, code, info, &opts);
794 return;
795 }
796
797 if (skb_shared(skb_in))
798 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
799
800 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
801 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
802 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
803 skb_network_offset(skb_in) + sizeof(struct iphdr))))
804 goto out;
805
806 orig_ip = ip_hdr(skb_in)->saddr;
807 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
808 __icmp_send(skb_in, type, code, info, &opts);
809 ip_hdr(skb_in)->saddr = orig_ip;
810out:
811 consume_skb(cloned_skb);
812}
813EXPORT_SYMBOL(icmp_ndo_send);
814#endif
815
816static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
817{
818 const struct iphdr *iph = (const struct iphdr *)skb->data;
819 const struct net_protocol *ipprot;
820 int protocol = iph->protocol;
821
822 /* Checkin full IP header plus 8 bytes of protocol to
823 * avoid additional coding at protocol handlers.
824 */
825 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
826 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
827 return;
828 }
829
830 raw_icmp_error(skb, protocol, info);
831
832 ipprot = rcu_dereference(inet_protos[protocol]);
833 if (ipprot && ipprot->err_handler)
834 ipprot->err_handler(skb, info);
835}
836
837static bool icmp_tag_validation(int proto)
838{
839 bool ok;
840
841 rcu_read_lock();
842 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
843 rcu_read_unlock();
844 return ok;
845}
846
847/*
848 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
849 * ICMP_PARAMETERPROB.
850 */
851
852static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
853{
854 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
855 const struct iphdr *iph;
856 struct icmphdr *icmph;
857 struct net *net;
858 u32 info = 0;
859
860 net = dev_net(skb_dst(skb)->dev);
861
862 /*
863 * Incomplete header ?
864 * Only checks for the IP header, there should be an
865 * additional check for longer headers in upper levels.
866 */
867
868 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
869 goto out_err;
870
871 icmph = icmp_hdr(skb);
872 iph = (const struct iphdr *)skb->data;
873
874 if (iph->ihl < 5) { /* Mangled header, drop. */
875 reason = SKB_DROP_REASON_IP_INHDR;
876 goto out_err;
877 }
878
879 switch (icmph->type) {
880 case ICMP_DEST_UNREACH:
881 switch (icmph->code & 15) {
882 case ICMP_NET_UNREACH:
883 case ICMP_HOST_UNREACH:
884 case ICMP_PROT_UNREACH:
885 case ICMP_PORT_UNREACH:
886 break;
887 case ICMP_FRAG_NEEDED:
888 /* for documentation of the ip_no_pmtu_disc
889 * values please see
890 * Documentation/networking/ip-sysctl.rst
891 */
892 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
893 default:
894 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
895 &iph->daddr);
896 break;
897 case 2:
898 goto out;
899 case 3:
900 if (!icmp_tag_validation(iph->protocol))
901 goto out;
902 fallthrough;
903 case 0:
904 info = ntohs(icmph->un.frag.mtu);
905 }
906 break;
907 case ICMP_SR_FAILED:
908 net_dbg_ratelimited("%pI4: Source Route Failed\n",
909 &iph->daddr);
910 break;
911 default:
912 break;
913 }
914 if (icmph->code > NR_ICMP_UNREACH)
915 goto out;
916 break;
917 case ICMP_PARAMETERPROB:
918 info = ntohl(icmph->un.gateway) >> 24;
919 break;
920 case ICMP_TIME_EXCEEDED:
921 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
922 if (icmph->code == ICMP_EXC_FRAGTIME)
923 goto out;
924 break;
925 }
926
927 /*
928 * Throw it at our lower layers
929 *
930 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
931 * header.
932 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
933 * transport layer.
934 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
935 * transport layer.
936 */
937
938 /*
939 * Check the other end isn't violating RFC 1122. Some routers send
940 * bogus responses to broadcast frames. If you see this message
941 * first check your netmask matches at both ends, if it does then
942 * get the other vendor to fix their kit.
943 */
944
945 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
946 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
947 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
948 &ip_hdr(skb)->saddr,
949 icmph->type, icmph->code,
950 &iph->daddr, skb->dev->name);
951 goto out;
952 }
953
954 icmp_socket_deliver(skb, info);
955
956out:
957 return reason;
958out_err:
959 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
960 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
961}
962
963
964/*
965 * Handle ICMP_REDIRECT.
966 */
967
968static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
969{
970 if (skb->len < sizeof(struct iphdr)) {
971 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
972 return SKB_DROP_REASON_PKT_TOO_SMALL;
973 }
974
975 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
976 /* there aught to be a stat */
977 return SKB_DROP_REASON_NOMEM;
978 }
979
980 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
981 return SKB_NOT_DROPPED_YET;
982}
983
984/*
985 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
986 *
987 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
988 * requests.
989 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
990 * included in the reply.
991 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
992 * echo requests, MUST have default=NOT.
993 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
994 * Extended Echo Functionality, MUST be disabled by default
995 * See also WRT handling of options once they are done and working.
996 */
997
998static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
999{
1000 struct icmp_bxm icmp_param;
1001 struct net *net;
1002
1003 net = dev_net(skb_dst(skb)->dev);
1004 /* should there be an ICMP stat for ignored echos? */
1005 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1006 return SKB_NOT_DROPPED_YET;
1007
1008 icmp_param.data.icmph = *icmp_hdr(skb);
1009 icmp_param.skb = skb;
1010 icmp_param.offset = 0;
1011 icmp_param.data_len = skb->len;
1012 icmp_param.head_len = sizeof(struct icmphdr);
1013
1014 if (icmp_param.data.icmph.type == ICMP_ECHO)
1015 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1016 else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1017 return SKB_NOT_DROPPED_YET;
1018
1019 icmp_reply(&icmp_param, skb);
1020 return SKB_NOT_DROPPED_YET;
1021}
1022
1023/* Helper for icmp_echo and icmpv6_echo_reply.
1024 * Searches for net_device that matches PROBE interface identifier
1025 * and builds PROBE reply message in icmphdr.
1026 *
1027 * Returns false if PROBE responses are disabled via sysctl
1028 */
1029
1030bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1031{
1032 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1033 struct icmp_ext_echo_iio *iio, _iio;
1034 struct net *net = dev_net(skb->dev);
1035 struct net_device *dev;
1036 char buff[IFNAMSIZ];
1037 u16 ident_len;
1038 u8 status;
1039
1040 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1041 return false;
1042
1043 /* We currently only support probing interfaces on the proxy node
1044 * Check to ensure L-bit is set
1045 */
1046 if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1047 return false;
1048 /* Clear status bits in reply message */
1049 icmphdr->un.echo.sequence &= htons(0xFF00);
1050 if (icmphdr->type == ICMP_EXT_ECHO)
1051 icmphdr->type = ICMP_EXT_ECHOREPLY;
1052 else
1053 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1054 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1055 /* Size of iio is class_type dependent.
1056 * Only check header here and assign length based on ctype in the switch statement
1057 */
1058 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1059 if (!ext_hdr || !iio)
1060 goto send_mal_query;
1061 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1062 ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1063 goto send_mal_query;
1064 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1065 iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1066 sizeof(iio->extobj_hdr) + ident_len, &_iio);
1067 if (!iio)
1068 goto send_mal_query;
1069
1070 status = 0;
1071 dev = NULL;
1072 switch (iio->extobj_hdr.class_type) {
1073 case ICMP_EXT_ECHO_CTYPE_NAME:
1074 if (ident_len >= IFNAMSIZ)
1075 goto send_mal_query;
1076 memset(buff, 0, sizeof(buff));
1077 memcpy(buff, &iio->ident.name, ident_len);
1078 dev = dev_get_by_name(net, buff);
1079 break;
1080 case ICMP_EXT_ECHO_CTYPE_INDEX:
1081 if (ident_len != sizeof(iio->ident.ifindex))
1082 goto send_mal_query;
1083 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1084 break;
1085 case ICMP_EXT_ECHO_CTYPE_ADDR:
1086 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1087 ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1088 iio->ident.addr.ctype3_hdr.addrlen)
1089 goto send_mal_query;
1090 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1091 case ICMP_AFI_IP:
1092 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1093 goto send_mal_query;
1094 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1095 break;
1096#if IS_ENABLED(CONFIG_IPV6)
1097 case ICMP_AFI_IP6:
1098 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1099 goto send_mal_query;
1100 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1101 dev_hold(dev);
1102 break;
1103#endif
1104 default:
1105 goto send_mal_query;
1106 }
1107 break;
1108 default:
1109 goto send_mal_query;
1110 }
1111 if (!dev) {
1112 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1113 return true;
1114 }
1115 /* Fill bits in reply message */
1116 if (dev->flags & IFF_UP)
1117 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1118 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1119 status |= ICMP_EXT_ECHOREPLY_IPV4;
1120 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1121 status |= ICMP_EXT_ECHOREPLY_IPV6;
1122 dev_put(dev);
1123 icmphdr->un.echo.sequence |= htons(status);
1124 return true;
1125send_mal_query:
1126 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1127 return true;
1128}
1129EXPORT_SYMBOL_GPL(icmp_build_probe);
1130
1131/*
1132 * Handle ICMP Timestamp requests.
1133 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1134 * SHOULD be in the kernel for minimum random latency.
1135 * MUST be accurate to a few minutes.
1136 * MUST be updated at least at 15Hz.
1137 */
1138static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1139{
1140 struct icmp_bxm icmp_param;
1141 /*
1142 * Too short.
1143 */
1144 if (skb->len < 4)
1145 goto out_err;
1146
1147 /*
1148 * Fill in the current time as ms since midnight UT:
1149 */
1150 icmp_param.data.times[1] = inet_current_timestamp();
1151 icmp_param.data.times[2] = icmp_param.data.times[1];
1152
1153 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1154
1155 icmp_param.data.icmph = *icmp_hdr(skb);
1156 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1157 icmp_param.data.icmph.code = 0;
1158 icmp_param.skb = skb;
1159 icmp_param.offset = 0;
1160 icmp_param.data_len = 0;
1161 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1162 icmp_reply(&icmp_param, skb);
1163 return SKB_NOT_DROPPED_YET;
1164
1165out_err:
1166 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1167 return SKB_DROP_REASON_PKT_TOO_SMALL;
1168}
1169
1170static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1171{
1172 /* pretend it was a success */
1173 return SKB_NOT_DROPPED_YET;
1174}
1175
1176/*
1177 * Deal with incoming ICMP packets.
1178 */
1179int icmp_rcv(struct sk_buff *skb)
1180{
1181 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1182 struct rtable *rt = skb_rtable(skb);
1183 struct net *net = dev_net(rt->dst.dev);
1184 struct icmphdr *icmph;
1185
1186 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1187 struct sec_path *sp = skb_sec_path(skb);
1188 int nh;
1189
1190 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1191 XFRM_STATE_ICMP)) {
1192 reason = SKB_DROP_REASON_XFRM_POLICY;
1193 goto drop;
1194 }
1195
1196 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1197 goto drop;
1198
1199 nh = skb_network_offset(skb);
1200 skb_set_network_header(skb, sizeof(*icmph));
1201
1202 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN,
1203 skb)) {
1204 reason = SKB_DROP_REASON_XFRM_POLICY;
1205 goto drop;
1206 }
1207
1208 skb_set_network_header(skb, nh);
1209 }
1210
1211 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1212
1213 if (skb_checksum_simple_validate(skb))
1214 goto csum_error;
1215
1216 if (!pskb_pull(skb, sizeof(*icmph)))
1217 goto error;
1218
1219 icmph = icmp_hdr(skb);
1220
1221 ICMPMSGIN_INC_STATS(net, icmph->type);
1222
1223 /* Check for ICMP Extended Echo (PROBE) messages */
1224 if (icmph->type == ICMP_EXT_ECHO) {
1225 /* We can't use icmp_pointers[].handler() because it is an array of
1226 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1227 */
1228 reason = icmp_echo(skb);
1229 goto reason_check;
1230 }
1231
1232 if (icmph->type == ICMP_EXT_ECHOREPLY) {
1233 reason = ping_rcv(skb);
1234 goto reason_check;
1235 }
1236
1237 /*
1238 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1239 *
1240 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1241 * discarded.
1242 */
1243 if (icmph->type > NR_ICMP_TYPES) {
1244 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1245 goto error;
1246 }
1247
1248 /*
1249 * Parse the ICMP message
1250 */
1251
1252 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1253 /*
1254 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1255 * silently ignored (we let user decide with a sysctl).
1256 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1257 * discarded if to broadcast/multicast.
1258 */
1259 if ((icmph->type == ICMP_ECHO ||
1260 icmph->type == ICMP_TIMESTAMP) &&
1261 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1262 reason = SKB_DROP_REASON_INVALID_PROTO;
1263 goto error;
1264 }
1265 if (icmph->type != ICMP_ECHO &&
1266 icmph->type != ICMP_TIMESTAMP &&
1267 icmph->type != ICMP_ADDRESS &&
1268 icmph->type != ICMP_ADDRESSREPLY) {
1269 reason = SKB_DROP_REASON_INVALID_PROTO;
1270 goto error;
1271 }
1272 }
1273
1274 reason = icmp_pointers[icmph->type].handler(skb);
1275reason_check:
1276 if (!reason) {
1277 consume_skb(skb);
1278 return NET_RX_SUCCESS;
1279 }
1280
1281drop:
1282 kfree_skb_reason(skb, reason);
1283 return NET_RX_DROP;
1284csum_error:
1285 reason = SKB_DROP_REASON_ICMP_CSUM;
1286 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1287error:
1288 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1289 goto drop;
1290}
1291
1292static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1293{
1294 struct icmp_extobj_hdr *objh, _objh;
1295 struct icmp_ext_hdr *exth, _exth;
1296 u16 olen;
1297
1298 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1299 if (!exth)
1300 return false;
1301 if (exth->version != 2)
1302 return true;
1303
1304 if (exth->checksum &&
1305 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1306 return false;
1307
1308 off += sizeof(_exth);
1309 while (off < skb->len) {
1310 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1311 if (!objh)
1312 return false;
1313
1314 olen = ntohs(objh->length);
1315 if (olen < sizeof(_objh))
1316 return false;
1317
1318 off += olen;
1319 if (off > skb->len)
1320 return false;
1321 }
1322
1323 return true;
1324}
1325
1326void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1327 struct sock_ee_data_rfc4884 *out,
1328 int thlen, int off)
1329{
1330 int hlen;
1331
1332 /* original datagram headers: end of icmph to payload (skb->data) */
1333 hlen = -skb_transport_offset(skb) - thlen;
1334
1335 /* per rfc 4884: minimal datagram length of 128 bytes */
1336 if (off < 128 || off < hlen)
1337 return;
1338
1339 /* kernel has stripped headers: return payload offset in bytes */
1340 off -= hlen;
1341 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1342 return;
1343
1344 out->len = off;
1345
1346 if (!ip_icmp_error_rfc4884_validate(skb, off))
1347 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1348}
1349EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1350
1351int icmp_err(struct sk_buff *skb, u32 info)
1352{
1353 struct iphdr *iph = (struct iphdr *)skb->data;
1354 int offset = iph->ihl<<2;
1355 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1356 int type = icmp_hdr(skb)->type;
1357 int code = icmp_hdr(skb)->code;
1358 struct net *net = dev_net(skb->dev);
1359
1360 /*
1361 * Use ping_err to handle all icmp errors except those
1362 * triggered by ICMP_ECHOREPLY which sent from kernel.
1363 */
1364 if (icmph->type != ICMP_ECHOREPLY) {
1365 ping_err(skb, offset, info);
1366 return 0;
1367 }
1368
1369 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1370 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1371 else if (type == ICMP_REDIRECT)
1372 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1373
1374 return 0;
1375}
1376
1377/*
1378 * This table is the definition of how we handle ICMP.
1379 */
1380static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1381 [ICMP_ECHOREPLY] = {
1382 .handler = ping_rcv,
1383 },
1384 [1] = {
1385 .handler = icmp_discard,
1386 .error = 1,
1387 },
1388 [2] = {
1389 .handler = icmp_discard,
1390 .error = 1,
1391 },
1392 [ICMP_DEST_UNREACH] = {
1393 .handler = icmp_unreach,
1394 .error = 1,
1395 },
1396 [ICMP_SOURCE_QUENCH] = {
1397 .handler = icmp_unreach,
1398 .error = 1,
1399 },
1400 [ICMP_REDIRECT] = {
1401 .handler = icmp_redirect,
1402 .error = 1,
1403 },
1404 [6] = {
1405 .handler = icmp_discard,
1406 .error = 1,
1407 },
1408 [7] = {
1409 .handler = icmp_discard,
1410 .error = 1,
1411 },
1412 [ICMP_ECHO] = {
1413 .handler = icmp_echo,
1414 },
1415 [9] = {
1416 .handler = icmp_discard,
1417 .error = 1,
1418 },
1419 [10] = {
1420 .handler = icmp_discard,
1421 .error = 1,
1422 },
1423 [ICMP_TIME_EXCEEDED] = {
1424 .handler = icmp_unreach,
1425 .error = 1,
1426 },
1427 [ICMP_PARAMETERPROB] = {
1428 .handler = icmp_unreach,
1429 .error = 1,
1430 },
1431 [ICMP_TIMESTAMP] = {
1432 .handler = icmp_timestamp,
1433 },
1434 [ICMP_TIMESTAMPREPLY] = {
1435 .handler = icmp_discard,
1436 },
1437 [ICMP_INFO_REQUEST] = {
1438 .handler = icmp_discard,
1439 },
1440 [ICMP_INFO_REPLY] = {
1441 .handler = icmp_discard,
1442 },
1443 [ICMP_ADDRESS] = {
1444 .handler = icmp_discard,
1445 },
1446 [ICMP_ADDRESSREPLY] = {
1447 .handler = icmp_discard,
1448 },
1449};
1450
1451static int __net_init icmp_sk_init(struct net *net)
1452{
1453 /* Control parameters for ECHO replies. */
1454 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1455 net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1456 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1457
1458 /* Control parameter - ignore bogus broadcast responses? */
1459 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1460
1461 /*
1462 * Configurable global rate limit.
1463 *
1464 * ratelimit defines tokens/packet consumed for dst->rate_token
1465 * bucket ratemask defines which icmp types are ratelimited by
1466 * setting it's bit position.
1467 *
1468 * default:
1469 * dest unreachable (3), source quench (4),
1470 * time exceeded (11), parameter problem (12)
1471 */
1472
1473 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1474 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1475 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1476
1477 return 0;
1478}
1479
1480static struct pernet_operations __net_initdata icmp_sk_ops = {
1481 .init = icmp_sk_init,
1482};
1483
1484int __init icmp_init(void)
1485{
1486 int err, i;
1487
1488 for_each_possible_cpu(i) {
1489 struct sock *sk;
1490
1491 err = inet_ctl_sock_create(&sk, PF_INET,
1492 SOCK_RAW, IPPROTO_ICMP, &init_net);
1493 if (err < 0)
1494 return err;
1495
1496 per_cpu(ipv4_icmp_sk, i) = sk;
1497
1498 /* Enough space for 2 64K ICMP packets, including
1499 * sk_buff/skb_shared_info struct overhead.
1500 */
1501 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1502
1503 /*
1504 * Speedup sock_wfree()
1505 */
1506 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1507 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1508 }
1509 return register_pernet_subsys(&icmp_sk_ops);
1510}
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}