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/flow.h>
76#include <net/snmp.h>
77#include <net/ip.h>
78#include <net/route.h>
79#include <net/protocol.h>
80#include <net/icmp.h>
81#include <net/tcp.h>
82#include <net/udp.h>
83#include <net/raw.h>
84#include <net/ping.h>
85#include <linux/skbuff.h>
86#include <net/sock.h>
87#include <linux/errno.h>
88#include <linux/timer.h>
89#include <linux/init.h>
90#include <linux/uaccess.h>
91#include <net/checksum.h>
92#include <net/xfrm.h>
93#include <net/inet_common.h>
94#include <net/ip_fib.h>
95#include <net/l3mdev.h>
96#include <net/addrconf.h>
97#include <net/inet_dscp.h>
98#define CREATE_TRACE_POINTS
99#include <trace/events/icmp.h>
100
101/*
102 * Build xmit assembly blocks
103 */
104
105struct icmp_bxm {
106 struct sk_buff *skb;
107 int offset;
108 int data_len;
109
110 struct {
111 struct icmphdr icmph;
112 __be32 times[3];
113 } data;
114 int head_len;
115 struct ip_options_data replyopts;
116};
117
118/* An array of errno for error messages from dest unreach. */
119/* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
120
121const struct icmp_err icmp_err_convert[] = {
122 {
123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
124 .fatal = 0,
125 },
126 {
127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
128 .fatal = 0,
129 },
130 {
131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
132 .fatal = 1,
133 },
134 {
135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
136 .fatal = 1,
137 },
138 {
139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
140 .fatal = 0,
141 },
142 {
143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
144 .fatal = 0,
145 },
146 {
147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
148 .fatal = 1,
149 },
150 {
151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
152 .fatal = 1,
153 },
154 {
155 .errno = ENONET, /* ICMP_HOST_ISOLATED */
156 .fatal = 1,
157 },
158 {
159 .errno = ENETUNREACH, /* ICMP_NET_ANO */
160 .fatal = 1,
161 },
162 {
163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
164 .fatal = 1,
165 },
166 {
167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
168 .fatal = 0,
169 },
170 {
171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
172 .fatal = 0,
173 },
174 {
175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
176 .fatal = 1,
177 },
178 {
179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
180 .fatal = 1,
181 },
182 {
183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
184 .fatal = 1,
185 },
186};
187EXPORT_SYMBOL(icmp_err_convert);
188
189/*
190 * ICMP control array. This specifies what to do with each ICMP.
191 */
192
193struct icmp_control {
194 enum skb_drop_reason (*handler)(struct sk_buff *skb);
195 short error; /* This ICMP is classed as an error message */
196};
197
198static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
199
200static DEFINE_PER_CPU(struct sock *, ipv4_icmp_sk);
201
202/* Called with BH disabled */
203static inline struct sock *icmp_xmit_lock(struct net *net)
204{
205 struct sock *sk;
206
207 sk = this_cpu_read(ipv4_icmp_sk);
208
209 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
210 /* This can happen if the output path signals a
211 * dst_link_failure() for an outgoing ICMP packet.
212 */
213 return NULL;
214 }
215 sock_net_set(sk, net);
216 return sk;
217}
218
219static inline void icmp_xmit_unlock(struct sock *sk)
220{
221 sock_net_set(sk, net: &init_net);
222 spin_unlock(lock: &sk->sk_lock.slock);
223}
224
225/**
226 * icmp_global_allow - Are we allowed to send one more ICMP message ?
227 * @net: network namespace
228 *
229 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
230 * Returns false if we reached the limit and can not send another packet.
231 * Works in tandem with icmp_global_consume().
232 */
233bool icmp_global_allow(struct net *net)
234{
235 u32 delta, now, oldstamp;
236 int incr, new, old;
237
238 /* Note: many cpus could find this condition true.
239 * Then later icmp_global_consume() could consume more credits,
240 * this is an acceptable race.
241 */
242 if (atomic_read(v: &net->ipv4.icmp_global_credit) > 0)
243 return true;
244
245 now = jiffies;
246 oldstamp = READ_ONCE(net->ipv4.icmp_global_stamp);
247 delta = min_t(u32, now - oldstamp, HZ);
248 if (delta < HZ / 50)
249 return false;
250
251 incr = READ_ONCE(net->ipv4.sysctl_icmp_msgs_per_sec) * delta / HZ;
252 if (!incr)
253 return false;
254
255 if (cmpxchg(&net->ipv4.icmp_global_stamp, oldstamp, now) == oldstamp) {
256 old = atomic_read(v: &net->ipv4.icmp_global_credit);
257 do {
258 new = min(old + incr, READ_ONCE(net->ipv4.sysctl_icmp_msgs_burst));
259 } while (!atomic_try_cmpxchg(v: &net->ipv4.icmp_global_credit, old: &old, new));
260 }
261 return true;
262}
263EXPORT_SYMBOL(icmp_global_allow);
264
265void icmp_global_consume(struct net *net)
266{
267 int credits = get_random_u32_below(ceil: 3);
268
269 /* Note: this might make icmp_global.credit negative. */
270 if (credits)
271 atomic_sub(i: credits, v: &net->ipv4.icmp_global_credit);
272}
273EXPORT_SYMBOL(icmp_global_consume);
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 bool *apply_ratelimit)
293{
294 if (icmpv4_mask_allow(net, type, code))
295 return true;
296
297 if (icmp_global_allow(net)) {
298 *apply_ratelimit = true;
299 return true;
300 }
301 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL);
302 return false;
303}
304
305/*
306 * Send an ICMP frame.
307 */
308
309static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
310 struct flowi4 *fl4, int type, int code,
311 bool apply_ratelimit)
312{
313 struct dst_entry *dst = &rt->dst;
314 struct inet_peer *peer;
315 struct net_device *dev;
316 bool rc = true;
317
318 if (!apply_ratelimit)
319 return true;
320
321 /* No rate limit on loopback */
322 rcu_read_lock();
323 dev = dst_dev_rcu(dst);
324 if (dev && (dev->flags & IFF_LOOPBACK))
325 goto out;
326
327 peer = inet_getpeer_v4(base: net->ipv4.peers, v4daddr: fl4->daddr,
328 vif: l3mdev_master_ifindex_rcu(dev));
329 rc = inet_peer_xrlim_allow(peer,
330 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
331out:
332 rcu_read_unlock();
333 if (!rc)
334 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITHOST);
335 else
336 icmp_global_consume(net);
337 return rc;
338}
339
340/*
341 * Maintain the counters used in the SNMP statistics for outgoing ICMP
342 */
343void icmp_out_count(struct net *net, unsigned char type)
344{
345 ICMPMSGOUT_INC_STATS(net, type);
346 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
347}
348
349/*
350 * Checksum each fragment, and on the first include the headers and final
351 * checksum.
352 */
353static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
354 struct sk_buff *skb)
355{
356 struct icmp_bxm *icmp_param = from;
357 __wsum csum;
358
359 csum = skb_copy_and_csum_bits(skb: icmp_param->skb,
360 offset: icmp_param->offset + offset,
361 to, len);
362
363 skb->csum = csum_block_add(csum: skb->csum, csum2: csum, offset: odd);
364 if (icmp_pointers[icmp_param->data.icmph.type].error)
365 nf_ct_attach(skb, icmp_param->skb);
366 return 0;
367}
368
369static void icmp_push_reply(struct sock *sk,
370 struct icmp_bxm *icmp_param,
371 struct flowi4 *fl4,
372 struct ipcm_cookie *ipc, struct rtable **rt)
373{
374 struct sk_buff *skb;
375
376 if (ip_append_data(sk, fl4, getfrag: icmp_glue_bits, from: icmp_param,
377 len: icmp_param->data_len+icmp_param->head_len,
378 protolen: icmp_param->head_len,
379 ipc, rt, MSG_DONTWAIT) < 0) {
380 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
381 ip_flush_pending_frames(sk);
382 } else if ((skb = skb_peek(list_: &sk->sk_write_queue)) != NULL) {
383 struct icmphdr *icmph = icmp_hdr(skb);
384 __wsum csum;
385 struct sk_buff *skb1;
386
387 csum = csum_partial_copy_nocheck(src: (void *)&icmp_param->data,
388 dst: (char *)icmph,
389 len: icmp_param->head_len);
390 skb_queue_walk(&sk->sk_write_queue, skb1) {
391 csum = csum_add(csum, addend: skb1->csum);
392 }
393 icmph->checksum = csum_fold(csum);
394 skb->ip_summed = CHECKSUM_NONE;
395 ip_push_pending_frames(sk, fl4);
396 }
397}
398
399/*
400 * Driving logic for building and sending ICMP messages.
401 */
402
403static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
404{
405 struct rtable *rt = skb_rtable(skb);
406 struct net *net = dev_net_rcu(dev: rt->dst.dev);
407 bool apply_ratelimit = false;
408 struct ipcm_cookie ipc;
409 struct flowi4 fl4;
410 struct sock *sk;
411 __be32 daddr, saddr;
412 u32 mark = IP4_REPLY_MARK(net, skb->mark);
413 int type = icmp_param->data.icmph.type;
414 int code = icmp_param->data.icmph.code;
415
416 if (ip_options_echo(net, dopt: &icmp_param->replyopts.opt.opt, skb))
417 return;
418
419 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */
420 local_bh_disable();
421
422 /* is global icmp_msgs_per_sec exhausted ? */
423 if (!icmpv4_global_allow(net, type, code, apply_ratelimit: &apply_ratelimit))
424 goto out_bh_enable;
425
426 sk = icmp_xmit_lock(net);
427 if (!sk)
428 goto out_bh_enable;
429
430 icmp_param->data.icmph.checksum = 0;
431
432 ipcm_init(ipcm: &ipc);
433 ipc.tos = ip_hdr(skb)->tos;
434 ipc.sockc.mark = mark;
435 daddr = ipc.addr = ip_hdr(skb)->saddr;
436 saddr = fib_compute_spec_dst(skb);
437
438 if (icmp_param->replyopts.opt.opt.optlen) {
439 ipc.opt = &icmp_param->replyopts.opt;
440 if (ipc.opt->opt.srr)
441 daddr = icmp_param->replyopts.opt.opt.faddr;
442 }
443 memset(&fl4, 0, sizeof(fl4));
444 fl4.daddr = daddr;
445 fl4.saddr = saddr;
446 fl4.flowi4_mark = mark;
447 fl4.flowi4_uid = sock_net_uid(net, NULL);
448 fl4.flowi4_dscp = ip4h_dscp(ip4h: ip_hdr(skb));
449 fl4.flowi4_proto = IPPROTO_ICMP;
450 fl4.flowi4_oif = l3mdev_master_ifindex(dev: skb->dev);
451 security_skb_classify_flow(skb, flic: flowi4_to_flowi_common(fl4: &fl4));
452 rt = ip_route_output_key(net, flp: &fl4);
453 if (IS_ERR(ptr: rt))
454 goto out_unlock;
455 if (icmpv4_xrlim_allow(net, rt, fl4: &fl4, type, code, apply_ratelimit))
456 icmp_push_reply(sk, icmp_param, fl4: &fl4, ipc: &ipc, rt: &rt);
457 ip_rt_put(rt);
458out_unlock:
459 icmp_xmit_unlock(sk);
460out_bh_enable:
461 local_bh_enable();
462}
463
464/*
465 * The device used for looking up which routing table to use for sending an ICMP
466 * error is preferably the source whenever it is set, which should ensure the
467 * icmp error can be sent to the source host, else lookup using the routing
468 * table of the destination device, else use the main routing table (index 0).
469 */
470static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
471{
472 struct net_device *dev = skb->dev;
473 const struct dst_entry *dst;
474
475 if (dev)
476 return dev;
477 dst = skb_dst(skb);
478 return dst ? dst_dev(dst) : NULL;
479}
480
481static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
482 struct sk_buff *skb_in,
483 const struct iphdr *iph, __be32 saddr,
484 dscp_t dscp, u32 mark, int type,
485 int code, struct icmp_bxm *param)
486{
487 struct net_device *route_lookup_dev;
488 struct dst_entry *dst, *dst2;
489 struct rtable *rt, *rt2;
490 struct flowi4 fl4_dec;
491 int err;
492
493 memset(fl4, 0, sizeof(*fl4));
494 fl4->daddr = (param->replyopts.opt.opt.srr ?
495 param->replyopts.opt.opt.faddr : iph->saddr);
496 fl4->saddr = saddr;
497 fl4->flowi4_mark = mark;
498 fl4->flowi4_uid = sock_net_uid(net, NULL);
499 fl4->flowi4_dscp = dscp;
500 fl4->flowi4_proto = IPPROTO_ICMP;
501 fl4->fl4_icmp_type = type;
502 fl4->fl4_icmp_code = code;
503 route_lookup_dev = icmp_get_route_lookup_dev(skb: skb_in);
504 fl4->flowi4_oif = l3mdev_master_ifindex(dev: route_lookup_dev);
505
506 security_skb_classify_flow(skb: skb_in, flic: flowi4_to_flowi_common(fl4));
507 rt = ip_route_output_key_hash(net, flp: fl4, skb: skb_in);
508 if (IS_ERR(ptr: rt))
509 return rt;
510
511 /* No need to clone since we're just using its address. */
512 rt2 = rt;
513
514 dst = xfrm_lookup(net, dst_orig: &rt->dst,
515 fl: flowi4_to_flowi(fl4), NULL, flags: 0);
516 rt = dst_rtable(dst);
517 if (!IS_ERR(ptr: dst)) {
518 if (rt != rt2)
519 return rt;
520 if (inet_addr_type_dev_table(net, dev: route_lookup_dev,
521 addr: fl4->daddr) == RTN_LOCAL)
522 return rt;
523 } else if (PTR_ERR(ptr: dst) == -EPERM) {
524 rt = NULL;
525 } else {
526 return rt;
527 }
528 err = xfrm_decode_session_reverse(net, skb: skb_in, fl: flowi4_to_flowi(fl4: &fl4_dec), AF_INET);
529 if (err)
530 goto relookup_failed;
531
532 if (inet_addr_type_dev_table(net, dev: route_lookup_dev,
533 addr: fl4_dec.saddr) == RTN_LOCAL) {
534 rt2 = __ip_route_output_key(net, flp: &fl4_dec);
535 if (IS_ERR(ptr: rt2))
536 err = PTR_ERR(ptr: rt2);
537 } else {
538 struct flowi4 fl4_2 = {};
539 unsigned long orefdst;
540
541 fl4_2.daddr = fl4_dec.saddr;
542 rt2 = ip_route_output_key(net, flp: &fl4_2);
543 if (IS_ERR(ptr: rt2)) {
544 err = PTR_ERR(ptr: rt2);
545 goto relookup_failed;
546 }
547 /* Ugh! */
548 orefdst = skb_dstref_steal(skb: skb_in);
549 err = ip_route_input(skb: skb_in, dst: fl4_dec.daddr, src: fl4_dec.saddr,
550 dscp, devin: rt2->dst.dev) ? -EINVAL : 0;
551
552 dst_release(dst: &rt2->dst);
553 rt2 = skb_rtable(skb: skb_in);
554 /* steal dst entry from skb_in, don't drop refcnt */
555 skb_dstref_steal(skb: skb_in);
556 skb_dstref_restore(skb: skb_in, refdst: orefdst);
557 }
558
559 if (err)
560 goto relookup_failed;
561
562 dst2 = xfrm_lookup(net, dst_orig: &rt2->dst, fl: flowi4_to_flowi(fl4: &fl4_dec), NULL,
563 flags: XFRM_LOOKUP_ICMP);
564 rt2 = dst_rtable(dst2);
565 if (!IS_ERR(ptr: dst2)) {
566 dst_release(dst: &rt->dst);
567 memcpy(fl4, &fl4_dec, sizeof(*fl4));
568 rt = rt2;
569 } else if (PTR_ERR(ptr: dst2) == -EPERM) {
570 if (rt)
571 dst_release(dst: &rt->dst);
572 return rt2;
573 } else {
574 err = PTR_ERR(ptr: dst2);
575 goto relookup_failed;
576 }
577 return rt;
578
579relookup_failed:
580 if (rt)
581 return rt;
582 return ERR_PTR(error: err);
583}
584
585struct icmp_ext_iio_addr4_subobj {
586 __be16 afi;
587 __be16 reserved;
588 __be32 addr4;
589};
590
591static unsigned int icmp_ext_iio_len(void)
592{
593 return sizeof(struct icmp_extobj_hdr) +
594 /* ifIndex */
595 sizeof(__be32) +
596 /* Interface Address Sub-Object */
597 sizeof(struct icmp_ext_iio_addr4_subobj) +
598 /* Interface Name Sub-Object. Length must be a multiple of 4
599 * bytes.
600 */
601 ALIGN(sizeof(struct icmp_ext_iio_name_subobj), 4) +
602 /* MTU */
603 sizeof(__be32);
604}
605
606static unsigned int icmp_ext_max_len(u8 ext_objs)
607{
608 unsigned int ext_max_len;
609
610 ext_max_len = sizeof(struct icmp_ext_hdr);
611
612 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF))
613 ext_max_len += icmp_ext_iio_len();
614
615 return ext_max_len;
616}
617
618static __be32 icmp_ext_iio_addr4_find(const struct net_device *dev)
619{
620 struct in_device *in_dev;
621 struct in_ifaddr *ifa;
622
623 in_dev = __in_dev_get_rcu(dev);
624 if (!in_dev)
625 return 0;
626
627 /* It is unclear from RFC 5837 which IP address should be chosen, but
628 * it makes sense to choose a global unicast address.
629 */
630 in_dev_for_each_ifa_rcu(ifa, in_dev) {
631 if (READ_ONCE(ifa->ifa_flags) & IFA_F_SECONDARY)
632 continue;
633 if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
634 ipv4_is_multicast(addr: ifa->ifa_address))
635 continue;
636 return ifa->ifa_address;
637 }
638
639 return 0;
640}
641
642static void icmp_ext_iio_iif_append(struct net *net, struct sk_buff *skb,
643 int iif)
644{
645 struct icmp_ext_iio_name_subobj *name_subobj;
646 struct icmp_extobj_hdr *objh;
647 struct net_device *dev;
648 __be32 data;
649
650 if (!iif)
651 return;
652
653 /* Add the fields in the order specified by RFC 5837. */
654 objh = skb_put(skb, len: sizeof(*objh));
655 objh->class_num = ICMP_EXT_OBJ_CLASS_IIO;
656 objh->class_type = ICMP_EXT_CTYPE_IIO_ROLE(ICMP_EXT_CTYPE_IIO_ROLE_IIF);
657
658 data = htonl(iif);
659 skb_put_data(skb, data: &data, len: sizeof(__be32));
660 objh->class_type |= ICMP_EXT_CTYPE_IIO_IFINDEX;
661
662 rcu_read_lock();
663
664 dev = dev_get_by_index_rcu(net, ifindex: iif);
665 if (!dev)
666 goto out;
667
668 data = icmp_ext_iio_addr4_find(dev);
669 if (data) {
670 struct icmp_ext_iio_addr4_subobj *addr4_subobj;
671
672 addr4_subobj = skb_put_zero(skb, len: sizeof(*addr4_subobj));
673 addr4_subobj->afi = htons(ICMP_AFI_IP);
674 addr4_subobj->addr4 = data;
675 objh->class_type |= ICMP_EXT_CTYPE_IIO_IPADDR;
676 }
677
678 name_subobj = skb_put_zero(skb, ALIGN(sizeof(*name_subobj), 4));
679 name_subobj->len = ALIGN(sizeof(*name_subobj), 4);
680 netdev_copy_name(dev, name: name_subobj->name);
681 objh->class_type |= ICMP_EXT_CTYPE_IIO_NAME;
682
683 data = htonl(READ_ONCE(dev->mtu));
684 skb_put_data(skb, data: &data, len: sizeof(__be32));
685 objh->class_type |= ICMP_EXT_CTYPE_IIO_MTU;
686
687out:
688 rcu_read_unlock();
689 objh->length = htons(skb_tail_pointer(skb) - (unsigned char *)objh);
690}
691
692static void icmp_ext_objs_append(struct net *net, struct sk_buff *skb,
693 u8 ext_objs, int iif)
694{
695 if (ext_objs & BIT(ICMP_ERR_EXT_IIO_IIF))
696 icmp_ext_iio_iif_append(net, skb, iif);
697}
698
699static struct sk_buff *
700icmp_ext_append(struct net *net, struct sk_buff *skb_in, struct icmphdr *icmph,
701 unsigned int room, int iif)
702{
703 unsigned int payload_len, ext_max_len, ext_len;
704 struct icmp_ext_hdr *ext_hdr;
705 struct sk_buff *skb;
706 u8 ext_objs;
707 int nhoff;
708
709 switch (icmph->type) {
710 case ICMP_DEST_UNREACH:
711 case ICMP_TIME_EXCEEDED:
712 case ICMP_PARAMETERPROB:
713 break;
714 default:
715 return NULL;
716 }
717
718 ext_objs = READ_ONCE(net->ipv4.sysctl_icmp_errors_extension_mask);
719 if (!ext_objs)
720 return NULL;
721
722 ext_max_len = icmp_ext_max_len(ext_objs);
723 if (ICMP_EXT_ORIG_DGRAM_MIN_LEN + ext_max_len > room)
724 return NULL;
725
726 skb = skb_clone(skb: skb_in, GFP_ATOMIC);
727 if (!skb)
728 return NULL;
729
730 nhoff = skb_network_offset(skb);
731 payload_len = min(skb->len - nhoff, ICMP_EXT_ORIG_DGRAM_MIN_LEN);
732
733 if (!pskb_network_may_pull(skb, len: payload_len))
734 goto free_skb;
735
736 if (pskb_trim(skb, len: nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN) ||
737 __skb_put_padto(skb, len: nhoff + ICMP_EXT_ORIG_DGRAM_MIN_LEN, free_on_error: false))
738 goto free_skb;
739
740 if (pskb_expand_head(skb, nhead: 0, ntail: ext_max_len, GFP_ATOMIC))
741 goto free_skb;
742
743 ext_hdr = skb_put_zero(skb, len: sizeof(*ext_hdr));
744 ext_hdr->version = ICMP_EXT_VERSION_2;
745
746 icmp_ext_objs_append(net, skb, ext_objs, iif);
747
748 /* Do not send an empty extension structure. */
749 ext_len = skb_tail_pointer(skb) - (unsigned char *)ext_hdr;
750 if (ext_len == sizeof(*ext_hdr))
751 goto free_skb;
752
753 ext_hdr->checksum = ip_compute_csum(buff: ext_hdr, len: ext_len);
754 /* The length of the original datagram in 32-bit words (RFC 4884). */
755 icmph->un.reserved[1] = ICMP_EXT_ORIG_DGRAM_MIN_LEN / sizeof(u32);
756
757 return skb;
758
759free_skb:
760 consume_skb(skb);
761 return NULL;
762}
763
764/*
765 * Send an ICMP message in response to a situation
766 *
767 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
768 * MAY send more (we do).
769 * MUST NOT change this header information.
770 * MUST NOT reply to a multicast/broadcast IP address.
771 * MUST NOT reply to a multicast/broadcast MAC address.
772 * MUST reply to only the first fragment.
773 */
774
775void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
776 const struct inet_skb_parm *parm)
777{
778 struct iphdr *iph;
779 int room;
780 struct icmp_bxm icmp_param;
781 struct rtable *rt = skb_rtable(skb: skb_in);
782 bool apply_ratelimit = false;
783 struct sk_buff *ext_skb;
784 struct ipcm_cookie ipc;
785 struct flowi4 fl4;
786 __be32 saddr;
787 u8 tos;
788 u32 mark;
789 struct net *net;
790 struct sock *sk;
791
792 if (!rt)
793 return;
794
795 rcu_read_lock();
796
797 if (rt->dst.dev)
798 net = dev_net_rcu(dev: rt->dst.dev);
799 else if (skb_in->dev)
800 net = dev_net_rcu(dev: skb_in->dev);
801 else
802 goto out;
803
804 /*
805 * Find the original header. It is expected to be valid, of course.
806 * Check this, icmp_send is called from the most obscure devices
807 * sometimes.
808 */
809 iph = ip_hdr(skb: skb_in);
810
811 if ((u8 *)iph < skb_in->head ||
812 (skb_network_header(skb: skb_in) + sizeof(*iph)) >
813 skb_tail_pointer(skb: skb_in))
814 goto out;
815
816 /*
817 * No replies to physical multicast/broadcast
818 */
819 if (skb_in->pkt_type != PACKET_HOST)
820 goto out;
821
822 /*
823 * Now check at the protocol level
824 */
825 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
826 goto out;
827
828 /*
829 * Only reply to fragment 0. We byte re-order the constant
830 * mask for efficiency.
831 */
832 if (iph->frag_off & htons(IP_OFFSET))
833 goto out;
834
835 /*
836 * If we send an ICMP error to an ICMP error a mess would result..
837 */
838 if (icmp_pointers[type].error) {
839 /*
840 * We are an error, check if we are replying to an
841 * ICMP error
842 */
843 if (iph->protocol == IPPROTO_ICMP) {
844 u8 _inner_type, *itp;
845
846 itp = skb_header_pointer(skb: skb_in,
847 offset: skb_network_header(skb: skb_in) +
848 (iph->ihl << 2) +
849 offsetof(struct icmphdr,
850 type) -
851 skb_in->data,
852 len: sizeof(_inner_type),
853 buffer: &_inner_type);
854 if (!itp)
855 goto out;
856
857 /*
858 * Assume any unknown ICMP type is an error. This
859 * isn't specified by the RFC, but think about it..
860 */
861 if (*itp > NR_ICMP_TYPES ||
862 icmp_pointers[*itp].error)
863 goto out;
864 }
865 }
866
867 /* Needed by both icmpv4_global_allow and icmp_xmit_lock */
868 local_bh_disable();
869
870 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
871 * incoming dev is loopback. If outgoing dev change to not be
872 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
873 */
874 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
875 !icmpv4_global_allow(net, type, code, apply_ratelimit: &apply_ratelimit))
876 goto out_bh_enable;
877
878 sk = icmp_xmit_lock(net);
879 if (!sk)
880 goto out_bh_enable;
881
882 /*
883 * Construct source address and options.
884 */
885
886 saddr = iph->daddr;
887 if (!(rt->rt_flags & RTCF_LOCAL)) {
888 struct net_device *dev = NULL;
889
890 rcu_read_lock();
891 if (rt_is_input_route(rt) &&
892 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
893 dev = dev_get_by_index_rcu(net, ifindex: parm->iif ? parm->iif :
894 inet_iif(skb: skb_in));
895
896 if (dev)
897 saddr = inet_select_addr(dev, dst: iph->saddr,
898 scope: RT_SCOPE_LINK);
899 else
900 saddr = 0;
901 rcu_read_unlock();
902 }
903
904 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
905 IPTOS_PREC_INTERNETCONTROL) :
906 iph->tos;
907 mark = IP4_REPLY_MARK(net, skb_in->mark);
908
909 if (__ip_options_echo(net, dopt: &icmp_param.replyopts.opt.opt, skb: skb_in,
910 sopt: &parm->opt))
911 goto out_unlock;
912
913
914 /*
915 * Prepare data for ICMP header.
916 */
917
918 icmp_param.data.icmph.type = type;
919 icmp_param.data.icmph.code = code;
920 icmp_param.data.icmph.un.gateway = info;
921 icmp_param.data.icmph.checksum = 0;
922 icmp_param.skb = skb_in;
923 icmp_param.offset = skb_network_offset(skb: skb_in);
924 ipcm_init(ipcm: &ipc);
925 ipc.tos = tos;
926 ipc.addr = iph->saddr;
927 ipc.opt = &icmp_param.replyopts.opt;
928 ipc.sockc.mark = mark;
929
930 rt = icmp_route_lookup(net, fl4: &fl4, skb_in, iph, saddr,
931 dscp: inet_dsfield_to_dscp(dsfield: tos), mark, type, code,
932 param: &icmp_param);
933 if (IS_ERR(ptr: rt))
934 goto out_unlock;
935
936 /* peer icmp_ratelimit */
937 if (!icmpv4_xrlim_allow(net, rt, fl4: &fl4, type, code, apply_ratelimit))
938 goto ende;
939
940 /* RFC says return as much as we can without exceeding 576 bytes. */
941
942 room = dst_mtu(dst: &rt->dst);
943 if (room > 576)
944 room = 576;
945 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
946 room -= sizeof(struct icmphdr);
947 /* Guard against tiny mtu. We need to include at least one
948 * IP network header for this message to make any sense.
949 */
950 if (room <= (int)sizeof(struct iphdr))
951 goto ende;
952
953 ext_skb = icmp_ext_append(net, skb_in, icmph: &icmp_param.data.icmph, room,
954 iif: parm->iif);
955 if (ext_skb)
956 icmp_param.skb = ext_skb;
957
958 icmp_param.data_len = icmp_param.skb->len - icmp_param.offset;
959 if (icmp_param.data_len > room)
960 icmp_param.data_len = room;
961 icmp_param.head_len = sizeof(struct icmphdr);
962
963 /* if we don't have a source address at this point, fall back to the
964 * dummy address instead of sending out a packet with a source address
965 * of 0.0.0.0
966 */
967 if (!fl4.saddr)
968 fl4.saddr = htonl(INADDR_DUMMY);
969
970 trace_icmp_send(skb: skb_in, type, code);
971
972 icmp_push_reply(sk, icmp_param: &icmp_param, fl4: &fl4, ipc: &ipc, rt: &rt);
973
974 if (ext_skb)
975 consume_skb(skb: ext_skb);
976ende:
977 ip_rt_put(rt);
978out_unlock:
979 icmp_xmit_unlock(sk);
980out_bh_enable:
981 local_bh_enable();
982out:
983 rcu_read_unlock();
984}
985EXPORT_SYMBOL(__icmp_send);
986
987#if IS_ENABLED(CONFIG_NF_NAT)
988#include <net/netfilter/nf_conntrack.h>
989void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
990{
991 struct sk_buff *cloned_skb = NULL;
992 enum ip_conntrack_info ctinfo;
993 enum ip_conntrack_dir dir;
994 struct inet_skb_parm parm;
995 struct nf_conn *ct;
996 __be32 orig_ip;
997
998 memset(&parm, 0, sizeof(parm));
999 ct = nf_ct_get(skb: skb_in, ctinfo: &ctinfo);
1000 if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) {
1001 __icmp_send(skb_in, type, code, info, &parm);
1002 return;
1003 }
1004
1005 if (skb_shared(skb: skb_in))
1006 skb_in = cloned_skb = skb_clone(skb: skb_in, GFP_ATOMIC);
1007
1008 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
1009 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
1010 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
1011 skb_network_offset(skb_in) + sizeof(struct iphdr))))
1012 goto out;
1013
1014 orig_ip = ip_hdr(skb: skb_in)->saddr;
1015 dir = CTINFO2DIR(ctinfo);
1016 ip_hdr(skb: skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip;
1017 __icmp_send(skb_in, type, code, info, &parm);
1018 ip_hdr(skb: skb_in)->saddr = orig_ip;
1019out:
1020 consume_skb(skb: cloned_skb);
1021}
1022EXPORT_SYMBOL(icmp_ndo_send);
1023#endif
1024
1025static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
1026{
1027 const struct iphdr *iph = (const struct iphdr *)skb->data;
1028 const struct net_protocol *ipprot;
1029 int protocol = iph->protocol;
1030
1031 /* Checkin full IP header plus 8 bytes of protocol to
1032 * avoid additional coding at protocol handlers.
1033 */
1034 if (!pskb_may_pull(skb, len: iph->ihl * 4 + 8)) {
1035 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
1036 return;
1037 }
1038
1039 raw_icmp_error(skb, protocol, info);
1040
1041 ipprot = rcu_dereference(inet_protos[protocol]);
1042 if (ipprot && ipprot->err_handler)
1043 ipprot->err_handler(skb, info);
1044}
1045
1046static bool icmp_tag_validation(int proto)
1047{
1048 bool ok;
1049
1050 rcu_read_lock();
1051 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
1052 rcu_read_unlock();
1053 return ok;
1054}
1055
1056/*
1057 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
1058 * ICMP_PARAMETERPROB.
1059 */
1060
1061static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
1062{
1063 enum skb_drop_reason reason = SKB_NOT_DROPPED_YET;
1064 const struct iphdr *iph;
1065 struct icmphdr *icmph;
1066 struct net *net;
1067 u32 info = 0;
1068
1069 net = skb_dst_dev_net_rcu(skb);
1070
1071 /*
1072 * Incomplete header ?
1073 * Only checks for the IP header, there should be an
1074 * additional check for longer headers in upper levels.
1075 */
1076
1077 if (!pskb_may_pull(skb, len: sizeof(struct iphdr)))
1078 goto out_err;
1079
1080 icmph = icmp_hdr(skb);
1081 iph = (const struct iphdr *)skb->data;
1082
1083 if (iph->ihl < 5) { /* Mangled header, drop. */
1084 reason = SKB_DROP_REASON_IP_INHDR;
1085 goto out_err;
1086 }
1087
1088 switch (icmph->type) {
1089 case ICMP_DEST_UNREACH:
1090 switch (icmph->code & 15) {
1091 case ICMP_NET_UNREACH:
1092 case ICMP_HOST_UNREACH:
1093 case ICMP_PROT_UNREACH:
1094 case ICMP_PORT_UNREACH:
1095 break;
1096 case ICMP_FRAG_NEEDED:
1097 /* for documentation of the ip_no_pmtu_disc
1098 * values please see
1099 * Documentation/networking/ip-sysctl.rst
1100 */
1101 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
1102 default:
1103 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
1104 &iph->daddr);
1105 break;
1106 case 2:
1107 goto out;
1108 case 3:
1109 if (!icmp_tag_validation(proto: iph->protocol))
1110 goto out;
1111 fallthrough;
1112 case 0:
1113 info = ntohs(icmph->un.frag.mtu);
1114 }
1115 break;
1116 case ICMP_SR_FAILED:
1117 net_dbg_ratelimited("%pI4: Source Route Failed\n",
1118 &iph->daddr);
1119 break;
1120 default:
1121 break;
1122 }
1123 if (icmph->code > NR_ICMP_UNREACH)
1124 goto out;
1125 break;
1126 case ICMP_PARAMETERPROB:
1127 info = ntohl(icmph->un.gateway) >> 24;
1128 break;
1129 case ICMP_TIME_EXCEEDED:
1130 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
1131 if (icmph->code == ICMP_EXC_FRAGTIME)
1132 goto out;
1133 break;
1134 }
1135
1136 /*
1137 * Throw it at our lower layers
1138 *
1139 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
1140 * header.
1141 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
1142 * transport layer.
1143 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
1144 * transport layer.
1145 */
1146
1147 /*
1148 * Check the other end isn't violating RFC 1122. Some routers send
1149 * bogus responses to broadcast frames. If you see this message
1150 * first check your netmask matches at both ends, if it does then
1151 * get the other vendor to fix their kit.
1152 */
1153
1154 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
1155 inet_addr_type_dev_table(net, dev: skb->dev, addr: iph->daddr) == RTN_BROADCAST) {
1156 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
1157 &ip_hdr(skb)->saddr,
1158 icmph->type, icmph->code,
1159 &iph->daddr, skb->dev->name);
1160 goto out;
1161 }
1162
1163 icmp_socket_deliver(skb, info);
1164
1165out:
1166 return reason;
1167out_err:
1168 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1169 return reason ?: SKB_DROP_REASON_NOT_SPECIFIED;
1170}
1171
1172
1173/*
1174 * Handle ICMP_REDIRECT.
1175 */
1176
1177static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
1178{
1179 if (skb->len < sizeof(struct iphdr)) {
1180 __ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
1181 return SKB_DROP_REASON_PKT_TOO_SMALL;
1182 }
1183
1184 if (!pskb_may_pull(skb, len: sizeof(struct iphdr))) {
1185 /* there aught to be a stat */
1186 return SKB_DROP_REASON_NOMEM;
1187 }
1188
1189 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
1190 return SKB_NOT_DROPPED_YET;
1191}
1192
1193/*
1194 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
1195 *
1196 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
1197 * requests.
1198 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
1199 * included in the reply.
1200 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
1201 * echo requests, MUST have default=NOT.
1202 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
1203 * Extended Echo Functionality, MUST be disabled by default
1204 * See also WRT handling of options once they are done and working.
1205 */
1206
1207static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
1208{
1209 struct icmp_bxm icmp_param;
1210 struct net *net;
1211
1212 net = skb_dst_dev_net_rcu(skb);
1213 /* should there be an ICMP stat for ignored echos? */
1214 if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
1215 return SKB_NOT_DROPPED_YET;
1216
1217 icmp_param.data.icmph = *icmp_hdr(skb);
1218 icmp_param.skb = skb;
1219 icmp_param.offset = 0;
1220 icmp_param.data_len = skb->len;
1221 icmp_param.head_len = sizeof(struct icmphdr);
1222
1223 if (icmp_param.data.icmph.type == ICMP_ECHO)
1224 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1225 else if (!icmp_build_probe(skb, icmphdr: &icmp_param.data.icmph))
1226 return SKB_NOT_DROPPED_YET;
1227
1228 icmp_reply(icmp_param: &icmp_param, skb);
1229 return SKB_NOT_DROPPED_YET;
1230}
1231
1232/* Helper for icmp_echo and icmpv6_echo_reply.
1233 * Searches for net_device that matches PROBE interface identifier
1234 * and builds PROBE reply message in icmphdr.
1235 *
1236 * Returns false if PROBE responses are disabled via sysctl
1237 */
1238
1239bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1240{
1241 struct net *net = dev_net_rcu(dev: skb->dev);
1242 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1243 struct icmp_ext_echo_iio *iio, _iio;
1244 struct inet6_dev *in6_dev;
1245 struct in_device *in_dev;
1246 struct net_device *dev;
1247 char buff[IFNAMSIZ];
1248 u16 ident_len;
1249 u8 status;
1250
1251 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1252 return false;
1253
1254 /* We currently only support probing interfaces on the proxy node
1255 * Check to ensure L-bit is set
1256 */
1257 if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1258 return false;
1259 /* Clear status bits in reply message */
1260 icmphdr->un.echo.sequence &= htons(0xFF00);
1261 if (icmphdr->type == ICMP_EXT_ECHO)
1262 icmphdr->type = ICMP_EXT_ECHOREPLY;
1263 else
1264 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1265 ext_hdr = skb_header_pointer(skb, offset: 0, len: sizeof(_ext_hdr), buffer: &_ext_hdr);
1266 /* Size of iio is class_type dependent.
1267 * Only check header here and assign length based on ctype in the switch statement
1268 */
1269 iio = skb_header_pointer(skb, offset: sizeof(_ext_hdr), len: sizeof(iio->extobj_hdr), buffer: &_iio);
1270 if (!ext_hdr || !iio)
1271 goto send_mal_query;
1272 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1273 ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1274 goto send_mal_query;
1275 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1276 iio = skb_header_pointer(skb, offset: sizeof(_ext_hdr),
1277 len: sizeof(iio->extobj_hdr) + ident_len, buffer: &_iio);
1278 if (!iio)
1279 goto send_mal_query;
1280
1281 status = 0;
1282 dev = NULL;
1283 switch (iio->extobj_hdr.class_type) {
1284 case ICMP_EXT_ECHO_CTYPE_NAME:
1285 if (ident_len >= IFNAMSIZ)
1286 goto send_mal_query;
1287 memset(buff, 0, sizeof(buff));
1288 memcpy(buff, &iio->ident.name, ident_len);
1289 dev = dev_get_by_name(net, name: buff);
1290 break;
1291 case ICMP_EXT_ECHO_CTYPE_INDEX:
1292 if (ident_len != sizeof(iio->ident.ifindex))
1293 goto send_mal_query;
1294 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1295 break;
1296 case ICMP_EXT_ECHO_CTYPE_ADDR:
1297 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1298 ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1299 iio->ident.addr.ctype3_hdr.addrlen)
1300 goto send_mal_query;
1301 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1302 case ICMP_AFI_IP:
1303 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1304 goto send_mal_query;
1305 dev = ip_dev_find(net, addr: iio->ident.addr.ip_addr.ipv4_addr);
1306 break;
1307#if IS_ENABLED(CONFIG_IPV6)
1308 case ICMP_AFI_IP6:
1309 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1310 goto send_mal_query;
1311 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1312 dev_hold(dev);
1313 break;
1314#endif
1315 default:
1316 goto send_mal_query;
1317 }
1318 break;
1319 default:
1320 goto send_mal_query;
1321 }
1322 if (!dev) {
1323 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1324 return true;
1325 }
1326 /* Fill bits in reply message */
1327 if (dev->flags & IFF_UP)
1328 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1329
1330 in_dev = __in_dev_get_rcu(dev);
1331 if (in_dev && rcu_access_pointer(in_dev->ifa_list))
1332 status |= ICMP_EXT_ECHOREPLY_IPV4;
1333
1334 in6_dev = __in6_dev_get(dev);
1335 if (in6_dev && !list_empty(head: &in6_dev->addr_list))
1336 status |= ICMP_EXT_ECHOREPLY_IPV6;
1337
1338 dev_put(dev);
1339 icmphdr->un.echo.sequence |= htons(status);
1340 return true;
1341send_mal_query:
1342 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1343 return true;
1344}
1345EXPORT_SYMBOL_GPL(icmp_build_probe);
1346
1347/*
1348 * Handle ICMP Timestamp requests.
1349 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1350 * SHOULD be in the kernel for minimum random latency.
1351 * MUST be accurate to a few minutes.
1352 * MUST be updated at least at 15Hz.
1353 */
1354static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
1355{
1356 struct icmp_bxm icmp_param;
1357 /*
1358 * Too short.
1359 */
1360 if (skb->len < 4)
1361 goto out_err;
1362
1363 /*
1364 * Fill in the current time as ms since midnight UT:
1365 */
1366 icmp_param.data.times[1] = inet_current_timestamp();
1367 icmp_param.data.times[2] = icmp_param.data.times[1];
1368
1369 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1370
1371 icmp_param.data.icmph = *icmp_hdr(skb);
1372 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1373 icmp_param.data.icmph.code = 0;
1374 icmp_param.skb = skb;
1375 icmp_param.offset = 0;
1376 icmp_param.data_len = 0;
1377 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1378 icmp_reply(icmp_param: &icmp_param, skb);
1379 return SKB_NOT_DROPPED_YET;
1380
1381out_err:
1382 __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS);
1383 return SKB_DROP_REASON_PKT_TOO_SMALL;
1384}
1385
1386static enum skb_drop_reason icmp_discard(struct sk_buff *skb)
1387{
1388 /* pretend it was a success */
1389 return SKB_NOT_DROPPED_YET;
1390}
1391
1392/*
1393 * Deal with incoming ICMP packets.
1394 */
1395int icmp_rcv(struct sk_buff *skb)
1396{
1397 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
1398 struct rtable *rt = skb_rtable(skb);
1399 struct net *net = dev_net_rcu(dev: rt->dst.dev);
1400 struct icmphdr *icmph;
1401
1402 if (!xfrm4_policy_check(NULL, dir: XFRM_POLICY_IN, skb)) {
1403 struct sec_path *sp = skb_sec_path(skb);
1404 int nh;
1405
1406 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1407 XFRM_STATE_ICMP)) {
1408 reason = SKB_DROP_REASON_XFRM_POLICY;
1409 goto drop;
1410 }
1411
1412 if (!pskb_may_pull(skb, len: sizeof(*icmph) + sizeof(struct iphdr)))
1413 goto drop;
1414
1415 nh = skb_network_offset(skb);
1416 skb_set_network_header(skb, offset: sizeof(*icmph));
1417
1418 if (!xfrm4_policy_check_reverse(NULL, dir: XFRM_POLICY_IN,
1419 skb)) {
1420 reason = SKB_DROP_REASON_XFRM_POLICY;
1421 goto drop;
1422 }
1423
1424 skb_set_network_header(skb, offset: nh);
1425 }
1426
1427 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1428
1429 if (skb_checksum_simple_validate(skb))
1430 goto csum_error;
1431
1432 if (!pskb_pull(skb, len: sizeof(*icmph)))
1433 goto error;
1434
1435 icmph = icmp_hdr(skb);
1436
1437 ICMPMSGIN_INC_STATS(net, icmph->type);
1438
1439 /* Check for ICMP Extended Echo (PROBE) messages */
1440 if (icmph->type == ICMP_EXT_ECHO) {
1441 /* We can't use icmp_pointers[].handler() because it is an array of
1442 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1443 */
1444 reason = icmp_echo(skb);
1445 goto reason_check;
1446 }
1447
1448 /*
1449 * Parse the ICMP message
1450 */
1451
1452 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1453 /*
1454 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1455 * silently ignored (we let user decide with a sysctl).
1456 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1457 * discarded if to broadcast/multicast.
1458 */
1459 if ((icmph->type == ICMP_ECHO ||
1460 icmph->type == ICMP_TIMESTAMP) &&
1461 READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
1462 reason = SKB_DROP_REASON_INVALID_PROTO;
1463 goto error;
1464 }
1465 if (icmph->type != ICMP_ECHO &&
1466 icmph->type != ICMP_TIMESTAMP &&
1467 icmph->type != ICMP_ADDRESS &&
1468 icmph->type != ICMP_ADDRESSREPLY) {
1469 reason = SKB_DROP_REASON_INVALID_PROTO;
1470 goto error;
1471 }
1472 }
1473
1474 if (icmph->type == ICMP_EXT_ECHOREPLY ||
1475 icmph->type == ICMP_ECHOREPLY) {
1476 reason = ping_rcv(skb);
1477 return reason ? NET_RX_DROP : NET_RX_SUCCESS;
1478 }
1479
1480 /*
1481 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1482 *
1483 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1484 * discarded.
1485 */
1486 if (icmph->type > NR_ICMP_TYPES) {
1487 reason = SKB_DROP_REASON_UNHANDLED_PROTO;
1488 goto error;
1489 }
1490
1491 reason = icmp_pointers[icmph->type].handler(skb);
1492reason_check:
1493 if (!reason) {
1494 consume_skb(skb);
1495 return NET_RX_SUCCESS;
1496 }
1497
1498drop:
1499 kfree_skb_reason(skb, reason);
1500 return NET_RX_DROP;
1501csum_error:
1502 reason = SKB_DROP_REASON_ICMP_CSUM;
1503 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1504error:
1505 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1506 goto drop;
1507}
1508
1509static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1510{
1511 struct icmp_extobj_hdr *objh, _objh;
1512 struct icmp_ext_hdr *exth, _exth;
1513 u16 olen;
1514
1515 exth = skb_header_pointer(skb, offset: off, len: sizeof(_exth), buffer: &_exth);
1516 if (!exth)
1517 return false;
1518 if (exth->version != 2)
1519 return true;
1520
1521 if (exth->checksum &&
1522 csum_fold(csum: skb_checksum(skb, offset: off, len: skb->len - off, csum: 0)))
1523 return false;
1524
1525 off += sizeof(_exth);
1526 while (off < skb->len) {
1527 objh = skb_header_pointer(skb, offset: off, len: sizeof(_objh), buffer: &_objh);
1528 if (!objh)
1529 return false;
1530
1531 olen = ntohs(objh->length);
1532 if (olen < sizeof(_objh))
1533 return false;
1534
1535 off += olen;
1536 if (off > skb->len)
1537 return false;
1538 }
1539
1540 return true;
1541}
1542
1543void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1544 struct sock_ee_data_rfc4884 *out,
1545 int thlen, int off)
1546{
1547 int hlen;
1548
1549 /* original datagram headers: end of icmph to payload (skb->data) */
1550 hlen = -skb_transport_offset(skb) - thlen;
1551
1552 /* per rfc 4884: minimal datagram length of 128 bytes */
1553 if (off < 128 || off < hlen)
1554 return;
1555
1556 /* kernel has stripped headers: return payload offset in bytes */
1557 off -= hlen;
1558 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1559 return;
1560
1561 out->len = off;
1562
1563 if (!ip_icmp_error_rfc4884_validate(skb, off))
1564 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1565}
1566EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1567
1568int icmp_err(struct sk_buff *skb, u32 info)
1569{
1570 struct iphdr *iph = (struct iphdr *)skb->data;
1571 int offset = iph->ihl<<2;
1572 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1573 struct net *net = dev_net_rcu(dev: skb->dev);
1574 int type = icmp_hdr(skb)->type;
1575 int code = icmp_hdr(skb)->code;
1576
1577 /*
1578 * Use ping_err to handle all icmp errors except those
1579 * triggered by ICMP_ECHOREPLY which sent from kernel.
1580 */
1581 if (icmph->type != ICMP_ECHOREPLY) {
1582 ping_err(skb, offset, info);
1583 return 0;
1584 }
1585
1586 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1587 ipv4_update_pmtu(skb, net, mtu: info, oif: 0, IPPROTO_ICMP);
1588 else if (type == ICMP_REDIRECT)
1589 ipv4_redirect(skb, net, oif: 0, IPPROTO_ICMP);
1590
1591 return 0;
1592}
1593
1594/*
1595 * This table is the definition of how we handle ICMP.
1596 */
1597static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1598 [ICMP_ECHOREPLY] = {
1599 .handler = ping_rcv,
1600 },
1601 [1] = {
1602 .handler = icmp_discard,
1603 .error = 1,
1604 },
1605 [2] = {
1606 .handler = icmp_discard,
1607 .error = 1,
1608 },
1609 [ICMP_DEST_UNREACH] = {
1610 .handler = icmp_unreach,
1611 .error = 1,
1612 },
1613 [ICMP_SOURCE_QUENCH] = {
1614 .handler = icmp_unreach,
1615 .error = 1,
1616 },
1617 [ICMP_REDIRECT] = {
1618 .handler = icmp_redirect,
1619 .error = 1,
1620 },
1621 [6] = {
1622 .handler = icmp_discard,
1623 .error = 1,
1624 },
1625 [7] = {
1626 .handler = icmp_discard,
1627 .error = 1,
1628 },
1629 [ICMP_ECHO] = {
1630 .handler = icmp_echo,
1631 },
1632 [9] = {
1633 .handler = icmp_discard,
1634 .error = 1,
1635 },
1636 [10] = {
1637 .handler = icmp_discard,
1638 .error = 1,
1639 },
1640 [ICMP_TIME_EXCEEDED] = {
1641 .handler = icmp_unreach,
1642 .error = 1,
1643 },
1644 [ICMP_PARAMETERPROB] = {
1645 .handler = icmp_unreach,
1646 .error = 1,
1647 },
1648 [ICMP_TIMESTAMP] = {
1649 .handler = icmp_timestamp,
1650 },
1651 [ICMP_TIMESTAMPREPLY] = {
1652 .handler = icmp_discard,
1653 },
1654 [ICMP_INFO_REQUEST] = {
1655 .handler = icmp_discard,
1656 },
1657 [ICMP_INFO_REPLY] = {
1658 .handler = icmp_discard,
1659 },
1660 [ICMP_ADDRESS] = {
1661 .handler = icmp_discard,
1662 },
1663 [ICMP_ADDRESSREPLY] = {
1664 .handler = icmp_discard,
1665 },
1666};
1667
1668static int __net_init icmp_sk_init(struct net *net)
1669{
1670 /* Control parameters for ECHO replies. */
1671 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1672 net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1673 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1674
1675 /* Control parameter - ignore bogus broadcast responses? */
1676 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1677
1678 /*
1679 * Configurable global rate limit.
1680 *
1681 * ratelimit defines tokens/packet consumed for dst->rate_token
1682 * bucket ratemask defines which icmp types are ratelimited by
1683 * setting it's bit position.
1684 *
1685 * default:
1686 * dest unreachable (3), source quench (4),
1687 * time exceeded (11), parameter problem (12)
1688 */
1689
1690 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1691 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1692 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1693 net->ipv4.sysctl_icmp_errors_extension_mask = 0;
1694 net->ipv4.sysctl_icmp_msgs_per_sec = 1000;
1695 net->ipv4.sysctl_icmp_msgs_burst = 50;
1696
1697 return 0;
1698}
1699
1700static struct pernet_operations __net_initdata icmp_sk_ops = {
1701 .init = icmp_sk_init,
1702};
1703
1704int __init icmp_init(void)
1705{
1706 int err, i;
1707
1708 for_each_possible_cpu(i) {
1709 struct sock *sk;
1710
1711 err = inet_ctl_sock_create(sk: &sk, PF_INET,
1712 type: SOCK_RAW, IPPROTO_ICMP, net: &init_net);
1713 if (err < 0)
1714 return err;
1715
1716 per_cpu(ipv4_icmp_sk, i) = sk;
1717
1718 /* Enough space for 2 64K ICMP packets, including
1719 * sk_buff/skb_shared_info struct overhead.
1720 */
1721 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1722
1723 /*
1724 * Speedup sock_wfree()
1725 */
1726 sock_set_flag(sk, flag: SOCK_USE_WRITE_QUEUE);
1727 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1728 }
1729 return register_pernet_subsys(&icmp_sk_ops);
1730}
1731

source code of linux/net/ipv4/icmp.c