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Merge tag 'pci-v5.10-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaa...
[mirror_ubuntu-jammy-kernel.git] / net / ipv4 / icmp.c
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
100 struct 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
116 const 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 };
182 EXPORT_SYMBOL(icmp_err_convert);
183
184 /*
185 * ICMP control array. This specifies what to do with each ICMP.
186 */
187
188 struct icmp_control {
189 bool (*handler)(struct sk_buff *skb);
190 short error; /* This ICMP is classed as an error message */
191 };
192
193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
194
195 /*
196 * The ICMP socket(s). This is the most convenient way to flow control
197 * our ICMP output as well as maintain a clean interface throughout
198 * all layers. All Socketless IP sends will soon be gone.
199 *
200 * On SMP we have one ICMP socket per-cpu.
201 */
202 static struct sock *icmp_sk(struct net *net)
203 {
204 return this_cpu_read(*net->ipv4.icmp_sk);
205 }
206
207 /* Called with BH disabled */
208 static inline struct sock *icmp_xmit_lock(struct net *net)
209 {
210 struct sock *sk;
211
212 sk = icmp_sk(net);
213
214 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
215 /* This can happen if the output path signals a
216 * dst_link_failure() for an outgoing ICMP packet.
217 */
218 return NULL;
219 }
220 return sk;
221 }
222
223 static inline void icmp_xmit_unlock(struct sock *sk)
224 {
225 spin_unlock(&sk->sk_lock.slock);
226 }
227
228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
229 int sysctl_icmp_msgs_burst __read_mostly = 50;
230
231 static struct {
232 spinlock_t lock;
233 u32 credit;
234 u32 stamp;
235 } icmp_global = {
236 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
237 };
238
239 /**
240 * icmp_global_allow - Are we allowed to send one more ICMP message ?
241 *
242 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
243 * Returns false if we reached the limit and can not send another packet.
244 * Note: called with BH disabled
245 */
246 bool icmp_global_allow(void)
247 {
248 u32 credit, delta, incr = 0, now = (u32)jiffies;
249 bool rc = false;
250
251 /* Check if token bucket is empty and cannot be refilled
252 * without taking the spinlock. The READ_ONCE() are paired
253 * with the following WRITE_ONCE() in this same function.
254 */
255 if (!READ_ONCE(icmp_global.credit)) {
256 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
257 if (delta < HZ / 50)
258 return false;
259 }
260
261 spin_lock(&icmp_global.lock);
262 delta = min_t(u32, now - icmp_global.stamp, HZ);
263 if (delta >= HZ / 50) {
264 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
265 if (incr)
266 WRITE_ONCE(icmp_global.stamp, now);
267 }
268 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
269 if (credit) {
270 /* We want to use a credit of one in average, but need to randomize
271 * it for security reasons.
272 */
273 credit = max_t(int, credit - prandom_u32_max(3), 0);
274 rc = true;
275 }
276 WRITE_ONCE(icmp_global.credit, credit);
277 spin_unlock(&icmp_global.lock);
278 return rc;
279 }
280 EXPORT_SYMBOL(icmp_global_allow);
281
282 static bool icmpv4_mask_allow(struct net *net, int type, int code)
283 {
284 if (type > NR_ICMP_TYPES)
285 return true;
286
287 /* Don't limit PMTU discovery. */
288 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
289 return true;
290
291 /* Limit if icmp type is enabled in ratemask. */
292 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
293 return true;
294
295 return false;
296 }
297
298 static bool icmpv4_global_allow(struct net *net, int type, int code)
299 {
300 if (icmpv4_mask_allow(net, type, code))
301 return true;
302
303 if (icmp_global_allow())
304 return true;
305
306 return false;
307 }
308
309 /*
310 * Send an ICMP frame.
311 */
312
313 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
314 struct flowi4 *fl4, int type, int code)
315 {
316 struct dst_entry *dst = &rt->dst;
317 struct inet_peer *peer;
318 bool rc = true;
319 int vif;
320
321 if (icmpv4_mask_allow(net, type, code))
322 goto out;
323
324 /* No rate limit on loopback */
325 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
326 goto out;
327
328 vif = l3mdev_master_ifindex(dst->dev);
329 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
330 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
331 if (peer)
332 inet_putpeer(peer);
333 out:
334 return rc;
335 }
336
337 /*
338 * Maintain the counters used in the SNMP statistics for outgoing ICMP
339 */
340 void icmp_out_count(struct net *net, unsigned char type)
341 {
342 ICMPMSGOUT_INC_STATS(net, type);
343 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
344 }
345
346 /*
347 * Checksum each fragment, and on the first include the headers and final
348 * checksum.
349 */
350 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
351 struct sk_buff *skb)
352 {
353 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
354 __wsum csum;
355
356 csum = skb_copy_and_csum_bits(icmp_param->skb,
357 icmp_param->offset + offset,
358 to, len);
359
360 skb->csum = csum_block_add(skb->csum, csum, odd);
361 if (icmp_pointers[icmp_param->data.icmph.type].error)
362 nf_ct_attach(skb, icmp_param->skb);
363 return 0;
364 }
365
366 static void icmp_push_reply(struct icmp_bxm *icmp_param,
367 struct flowi4 *fl4,
368 struct ipcm_cookie *ipc, struct rtable **rt)
369 {
370 struct sock *sk;
371 struct sk_buff *skb;
372
373 sk = icmp_sk(dev_net((*rt)->dst.dev));
374 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
375 icmp_param->data_len+icmp_param->head_len,
376 icmp_param->head_len,
377 ipc, rt, MSG_DONTWAIT) < 0) {
378 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
379 ip_flush_pending_frames(sk);
380 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
381 struct icmphdr *icmph = icmp_hdr(skb);
382 __wsum csum;
383 struct sk_buff *skb1;
384
385 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
386 (char *)icmph,
387 icmp_param->head_len);
388 skb_queue_walk(&sk->sk_write_queue, skb1) {
389 csum = csum_add(csum, skb1->csum);
390 }
391 icmph->checksum = csum_fold(csum);
392 skb->ip_summed = CHECKSUM_NONE;
393 ip_push_pending_frames(sk, fl4);
394 }
395 }
396
397 /*
398 * Driving logic for building and sending ICMP messages.
399 */
400
401 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
402 {
403 struct ipcm_cookie ipc;
404 struct rtable *rt = skb_rtable(skb);
405 struct net *net = dev_net(rt->dst.dev);
406 struct flowi4 fl4;
407 struct sock *sk;
408 struct inet_sock *inet;
409 __be32 daddr, saddr;
410 u32 mark = IP4_REPLY_MARK(net, skb->mark);
411 int type = icmp_param->data.icmph.type;
412 int code = icmp_param->data.icmph.code;
413
414 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
415 return;
416
417 /* Needed by both icmp_global_allow and icmp_xmit_lock */
418 local_bh_disable();
419
420 /* global icmp_msgs_per_sec */
421 if (!icmpv4_global_allow(net, type, code))
422 goto out_bh_enable;
423
424 sk = icmp_xmit_lock(net);
425 if (!sk)
426 goto out_bh_enable;
427 inet = inet_sk(sk);
428
429 icmp_param->data.icmph.checksum = 0;
430
431 ipcm_init(&ipc);
432 inet->tos = ip_hdr(skb)->tos;
433 ipc.sockc.mark = mark;
434 daddr = ipc.addr = ip_hdr(skb)->saddr;
435 saddr = fib_compute_spec_dst(skb);
436
437 if (icmp_param->replyopts.opt.opt.optlen) {
438 ipc.opt = &icmp_param->replyopts.opt;
439 if (ipc.opt->opt.srr)
440 daddr = icmp_param->replyopts.opt.opt.faddr;
441 }
442 memset(&fl4, 0, sizeof(fl4));
443 fl4.daddr = daddr;
444 fl4.saddr = saddr;
445 fl4.flowi4_mark = mark;
446 fl4.flowi4_uid = sock_net_uid(net, NULL);
447 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
448 fl4.flowi4_proto = IPPROTO_ICMP;
449 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
450 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
451 rt = ip_route_output_key(net, &fl4);
452 if (IS_ERR(rt))
453 goto out_unlock;
454 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
455 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
456 ip_rt_put(rt);
457 out_unlock:
458 icmp_xmit_unlock(sk);
459 out_bh_enable:
460 local_bh_enable();
461 }
462
463 /*
464 * The device used for looking up which routing table to use for sending an ICMP
465 * error is preferably the source whenever it is set, which should ensure the
466 * icmp error can be sent to the source host, else lookup using the routing
467 * table of the destination device, else use the main routing table (index 0).
468 */
469 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
470 {
471 struct net_device *route_lookup_dev = NULL;
472
473 if (skb->dev)
474 route_lookup_dev = skb->dev;
475 else if (skb_dst(skb))
476 route_lookup_dev = skb_dst(skb)->dev;
477 return route_lookup_dev;
478 }
479
480 static struct rtable *icmp_route_lookup(struct net *net,
481 struct flowi4 *fl4,
482 struct sk_buff *skb_in,
483 const struct iphdr *iph,
484 __be32 saddr, u8 tos, u32 mark,
485 int type, int code,
486 struct icmp_bxm *param)
487 {
488 struct net_device *route_lookup_dev;
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_tos = RT_TOS(tos);
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_in);
504 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
505
506 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
507 rt = ip_route_output_key_hash(net, fl4, skb_in);
508 if (IS_ERR(rt))
509 return rt;
510
511 /* No need to clone since we're just using its address. */
512 rt2 = rt;
513
514 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
515 flowi4_to_flowi(fl4), NULL, 0);
516 if (!IS_ERR(rt)) {
517 if (rt != rt2)
518 return rt;
519 } else if (PTR_ERR(rt) == -EPERM) {
520 rt = NULL;
521 } else
522 return rt;
523
524 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
525 if (err)
526 goto relookup_failed;
527
528 if (inet_addr_type_dev_table(net, route_lookup_dev,
529 fl4_dec.saddr) == RTN_LOCAL) {
530 rt2 = __ip_route_output_key(net, &fl4_dec);
531 if (IS_ERR(rt2))
532 err = PTR_ERR(rt2);
533 } else {
534 struct flowi4 fl4_2 = {};
535 unsigned long orefdst;
536
537 fl4_2.daddr = fl4_dec.saddr;
538 rt2 = ip_route_output_key(net, &fl4_2);
539 if (IS_ERR(rt2)) {
540 err = PTR_ERR(rt2);
541 goto relookup_failed;
542 }
543 /* Ugh! */
544 orefdst = skb_in->_skb_refdst; /* save old refdst */
545 skb_dst_set(skb_in, NULL);
546 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
547 RT_TOS(tos), rt2->dst.dev);
548
549 dst_release(&rt2->dst);
550 rt2 = skb_rtable(skb_in);
551 skb_in->_skb_refdst = orefdst; /* restore old refdst */
552 }
553
554 if (err)
555 goto relookup_failed;
556
557 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
558 flowi4_to_flowi(&fl4_dec), NULL,
559 XFRM_LOOKUP_ICMP);
560 if (!IS_ERR(rt2)) {
561 dst_release(&rt->dst);
562 memcpy(fl4, &fl4_dec, sizeof(*fl4));
563 rt = rt2;
564 } else if (PTR_ERR(rt2) == -EPERM) {
565 if (rt)
566 dst_release(&rt->dst);
567 return rt2;
568 } else {
569 err = PTR_ERR(rt2);
570 goto relookup_failed;
571 }
572 return rt;
573
574 relookup_failed:
575 if (rt)
576 return rt;
577 return ERR_PTR(err);
578 }
579
580 /*
581 * Send an ICMP message in response to a situation
582 *
583 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
584 * MAY send more (we do).
585 * MUST NOT change this header information.
586 * MUST NOT reply to a multicast/broadcast IP address.
587 * MUST NOT reply to a multicast/broadcast MAC address.
588 * MUST reply to only the first fragment.
589 */
590
591 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
592 const struct ip_options *opt)
593 {
594 struct iphdr *iph;
595 int room;
596 struct icmp_bxm icmp_param;
597 struct rtable *rt = skb_rtable(skb_in);
598 struct ipcm_cookie ipc;
599 struct flowi4 fl4;
600 __be32 saddr;
601 u8 tos;
602 u32 mark;
603 struct net *net;
604 struct sock *sk;
605
606 if (!rt)
607 goto out;
608
609 if (rt->dst.dev)
610 net = dev_net(rt->dst.dev);
611 else if (skb_in->dev)
612 net = dev_net(skb_in->dev);
613 else
614 goto out;
615
616 /*
617 * Find the original header. It is expected to be valid, of course.
618 * Check this, icmp_send is called from the most obscure devices
619 * sometimes.
620 */
621 iph = ip_hdr(skb_in);
622
623 if ((u8 *)iph < skb_in->head ||
624 (skb_network_header(skb_in) + sizeof(*iph)) >
625 skb_tail_pointer(skb_in))
626 goto out;
627
628 /*
629 * No replies to physical multicast/broadcast
630 */
631 if (skb_in->pkt_type != PACKET_HOST)
632 goto out;
633
634 /*
635 * Now check at the protocol level
636 */
637 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
638 goto out;
639
640 /*
641 * Only reply to fragment 0. We byte re-order the constant
642 * mask for efficiency.
643 */
644 if (iph->frag_off & htons(IP_OFFSET))
645 goto out;
646
647 /*
648 * If we send an ICMP error to an ICMP error a mess would result..
649 */
650 if (icmp_pointers[type].error) {
651 /*
652 * We are an error, check if we are replying to an
653 * ICMP error
654 */
655 if (iph->protocol == IPPROTO_ICMP) {
656 u8 _inner_type, *itp;
657
658 itp = skb_header_pointer(skb_in,
659 skb_network_header(skb_in) +
660 (iph->ihl << 2) +
661 offsetof(struct icmphdr,
662 type) -
663 skb_in->data,
664 sizeof(_inner_type),
665 &_inner_type);
666 if (!itp)
667 goto out;
668
669 /*
670 * Assume any unknown ICMP type is an error. This
671 * isn't specified by the RFC, but think about it..
672 */
673 if (*itp > NR_ICMP_TYPES ||
674 icmp_pointers[*itp].error)
675 goto out;
676 }
677 }
678
679 /* Needed by both icmp_global_allow and icmp_xmit_lock */
680 local_bh_disable();
681
682 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
683 * incoming dev is loopback. If outgoing dev change to not be
684 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
685 */
686 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
687 !icmpv4_global_allow(net, type, code))
688 goto out_bh_enable;
689
690 sk = icmp_xmit_lock(net);
691 if (!sk)
692 goto out_bh_enable;
693
694 /*
695 * Construct source address and options.
696 */
697
698 saddr = iph->daddr;
699 if (!(rt->rt_flags & RTCF_LOCAL)) {
700 struct net_device *dev = NULL;
701
702 rcu_read_lock();
703 if (rt_is_input_route(rt) &&
704 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
705 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
706
707 if (dev)
708 saddr = inet_select_addr(dev, iph->saddr,
709 RT_SCOPE_LINK);
710 else
711 saddr = 0;
712 rcu_read_unlock();
713 }
714
715 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
716 IPTOS_PREC_INTERNETCONTROL) :
717 iph->tos;
718 mark = IP4_REPLY_MARK(net, skb_in->mark);
719
720 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
721 goto out_unlock;
722
723
724 /*
725 * Prepare data for ICMP header.
726 */
727
728 icmp_param.data.icmph.type = type;
729 icmp_param.data.icmph.code = code;
730 icmp_param.data.icmph.un.gateway = info;
731 icmp_param.data.icmph.checksum = 0;
732 icmp_param.skb = skb_in;
733 icmp_param.offset = skb_network_offset(skb_in);
734 inet_sk(sk)->tos = tos;
735 ipcm_init(&ipc);
736 ipc.addr = iph->saddr;
737 ipc.opt = &icmp_param.replyopts.opt;
738 ipc.sockc.mark = mark;
739
740 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
741 type, code, &icmp_param);
742 if (IS_ERR(rt))
743 goto out_unlock;
744
745 /* peer icmp_ratelimit */
746 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
747 goto ende;
748
749 /* RFC says return as much as we can without exceeding 576 bytes. */
750
751 room = dst_mtu(&rt->dst);
752 if (room > 576)
753 room = 576;
754 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
755 room -= sizeof(struct icmphdr);
756
757 icmp_param.data_len = skb_in->len - icmp_param.offset;
758 if (icmp_param.data_len > room)
759 icmp_param.data_len = room;
760 icmp_param.head_len = sizeof(struct icmphdr);
761
762 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
763 ende:
764 ip_rt_put(rt);
765 out_unlock:
766 icmp_xmit_unlock(sk);
767 out_bh_enable:
768 local_bh_enable();
769 out:;
770 }
771 EXPORT_SYMBOL(__icmp_send);
772
773 #if IS_ENABLED(CONFIG_NF_NAT)
774 #include <net/netfilter/nf_conntrack.h>
775 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
776 {
777 struct sk_buff *cloned_skb = NULL;
778 enum ip_conntrack_info ctinfo;
779 struct nf_conn *ct;
780 __be32 orig_ip;
781
782 ct = nf_ct_get(skb_in, &ctinfo);
783 if (!ct || !(ct->status & IPS_SRC_NAT)) {
784 icmp_send(skb_in, type, code, info);
785 return;
786 }
787
788 if (skb_shared(skb_in))
789 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
790
791 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
792 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
793 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
794 skb_network_offset(skb_in) + sizeof(struct iphdr))))
795 goto out;
796
797 orig_ip = ip_hdr(skb_in)->saddr;
798 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
799 icmp_send(skb_in, type, code, info);
800 ip_hdr(skb_in)->saddr = orig_ip;
801 out:
802 consume_skb(cloned_skb);
803 }
804 EXPORT_SYMBOL(icmp_ndo_send);
805 #endif
806
807 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
808 {
809 const struct iphdr *iph = (const struct iphdr *)skb->data;
810 const struct net_protocol *ipprot;
811 int protocol = iph->protocol;
812
813 /* Checkin full IP header plus 8 bytes of protocol to
814 * avoid additional coding at protocol handlers.
815 */
816 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
817 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
818 return;
819 }
820
821 raw_icmp_error(skb, protocol, info);
822
823 ipprot = rcu_dereference(inet_protos[protocol]);
824 if (ipprot && ipprot->err_handler)
825 ipprot->err_handler(skb, info);
826 }
827
828 static bool icmp_tag_validation(int proto)
829 {
830 bool ok;
831
832 rcu_read_lock();
833 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
834 rcu_read_unlock();
835 return ok;
836 }
837
838 /*
839 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
840 * ICMP_PARAMETERPROB.
841 */
842
843 static bool icmp_unreach(struct sk_buff *skb)
844 {
845 const struct iphdr *iph;
846 struct icmphdr *icmph;
847 struct net *net;
848 u32 info = 0;
849
850 net = dev_net(skb_dst(skb)->dev);
851
852 /*
853 * Incomplete header ?
854 * Only checks for the IP header, there should be an
855 * additional check for longer headers in upper levels.
856 */
857
858 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
859 goto out_err;
860
861 icmph = icmp_hdr(skb);
862 iph = (const struct iphdr *)skb->data;
863
864 if (iph->ihl < 5) /* Mangled header, drop. */
865 goto out_err;
866
867 switch (icmph->type) {
868 case ICMP_DEST_UNREACH:
869 switch (icmph->code & 15) {
870 case ICMP_NET_UNREACH:
871 case ICMP_HOST_UNREACH:
872 case ICMP_PROT_UNREACH:
873 case ICMP_PORT_UNREACH:
874 break;
875 case ICMP_FRAG_NEEDED:
876 /* for documentation of the ip_no_pmtu_disc
877 * values please see
878 * Documentation/networking/ip-sysctl.rst
879 */
880 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
881 default:
882 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
883 &iph->daddr);
884 break;
885 case 2:
886 goto out;
887 case 3:
888 if (!icmp_tag_validation(iph->protocol))
889 goto out;
890 fallthrough;
891 case 0:
892 info = ntohs(icmph->un.frag.mtu);
893 }
894 break;
895 case ICMP_SR_FAILED:
896 net_dbg_ratelimited("%pI4: Source Route Failed\n",
897 &iph->daddr);
898 break;
899 default:
900 break;
901 }
902 if (icmph->code > NR_ICMP_UNREACH)
903 goto out;
904 break;
905 case ICMP_PARAMETERPROB:
906 info = ntohl(icmph->un.gateway) >> 24;
907 break;
908 case ICMP_TIME_EXCEEDED:
909 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
910 if (icmph->code == ICMP_EXC_FRAGTIME)
911 goto out;
912 break;
913 }
914
915 /*
916 * Throw it at our lower layers
917 *
918 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
919 * header.
920 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
921 * transport layer.
922 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
923 * transport layer.
924 */
925
926 /*
927 * Check the other end isn't violating RFC 1122. Some routers send
928 * bogus responses to broadcast frames. If you see this message
929 * first check your netmask matches at both ends, if it does then
930 * get the other vendor to fix their kit.
931 */
932
933 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
934 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
935 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
936 &ip_hdr(skb)->saddr,
937 icmph->type, icmph->code,
938 &iph->daddr, skb->dev->name);
939 goto out;
940 }
941
942 icmp_socket_deliver(skb, info);
943
944 out:
945 return true;
946 out_err:
947 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
948 return false;
949 }
950
951
952 /*
953 * Handle ICMP_REDIRECT.
954 */
955
956 static bool icmp_redirect(struct sk_buff *skb)
957 {
958 if (skb->len < sizeof(struct iphdr)) {
959 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
960 return false;
961 }
962
963 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
964 /* there aught to be a stat */
965 return false;
966 }
967
968 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
969 return true;
970 }
971
972 /*
973 * Handle ICMP_ECHO ("ping") requests.
974 *
975 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
976 * requests.
977 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
978 * included in the reply.
979 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
980 * echo requests, MUST have default=NOT.
981 * See also WRT handling of options once they are done and working.
982 */
983
984 static bool icmp_echo(struct sk_buff *skb)
985 {
986 struct net *net;
987
988 net = dev_net(skb_dst(skb)->dev);
989 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
990 struct icmp_bxm icmp_param;
991
992 icmp_param.data.icmph = *icmp_hdr(skb);
993 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
994 icmp_param.skb = skb;
995 icmp_param.offset = 0;
996 icmp_param.data_len = skb->len;
997 icmp_param.head_len = sizeof(struct icmphdr);
998 icmp_reply(&icmp_param, skb);
999 }
1000 /* should there be an ICMP stat for ignored echos? */
1001 return true;
1002 }
1003
1004 /*
1005 * Handle ICMP Timestamp requests.
1006 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1007 * SHOULD be in the kernel for minimum random latency.
1008 * MUST be accurate to a few minutes.
1009 * MUST be updated at least at 15Hz.
1010 */
1011 static bool icmp_timestamp(struct sk_buff *skb)
1012 {
1013 struct icmp_bxm icmp_param;
1014 /*
1015 * Too short.
1016 */
1017 if (skb->len < 4)
1018 goto out_err;
1019
1020 /*
1021 * Fill in the current time as ms since midnight UT:
1022 */
1023 icmp_param.data.times[1] = inet_current_timestamp();
1024 icmp_param.data.times[2] = icmp_param.data.times[1];
1025
1026 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1027
1028 icmp_param.data.icmph = *icmp_hdr(skb);
1029 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1030 icmp_param.data.icmph.code = 0;
1031 icmp_param.skb = skb;
1032 icmp_param.offset = 0;
1033 icmp_param.data_len = 0;
1034 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1035 icmp_reply(&icmp_param, skb);
1036 return true;
1037
1038 out_err:
1039 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1040 return false;
1041 }
1042
1043 static bool icmp_discard(struct sk_buff *skb)
1044 {
1045 /* pretend it was a success */
1046 return true;
1047 }
1048
1049 /*
1050 * Deal with incoming ICMP packets.
1051 */
1052 int icmp_rcv(struct sk_buff *skb)
1053 {
1054 struct icmphdr *icmph;
1055 struct rtable *rt = skb_rtable(skb);
1056 struct net *net = dev_net(rt->dst.dev);
1057 bool success;
1058
1059 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1060 struct sec_path *sp = skb_sec_path(skb);
1061 int nh;
1062
1063 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1064 XFRM_STATE_ICMP))
1065 goto drop;
1066
1067 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1068 goto drop;
1069
1070 nh = skb_network_offset(skb);
1071 skb_set_network_header(skb, sizeof(*icmph));
1072
1073 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1074 goto drop;
1075
1076 skb_set_network_header(skb, nh);
1077 }
1078
1079 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1080
1081 if (skb_checksum_simple_validate(skb))
1082 goto csum_error;
1083
1084 if (!pskb_pull(skb, sizeof(*icmph)))
1085 goto error;
1086
1087 icmph = icmp_hdr(skb);
1088
1089 ICMPMSGIN_INC_STATS(net, icmph->type);
1090 /*
1091 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1092 *
1093 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1094 * discarded.
1095 */
1096 if (icmph->type > NR_ICMP_TYPES)
1097 goto error;
1098
1099
1100 /*
1101 * Parse the ICMP message
1102 */
1103
1104 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1105 /*
1106 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1107 * silently ignored (we let user decide with a sysctl).
1108 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1109 * discarded if to broadcast/multicast.
1110 */
1111 if ((icmph->type == ICMP_ECHO ||
1112 icmph->type == ICMP_TIMESTAMP) &&
1113 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1114 goto error;
1115 }
1116 if (icmph->type != ICMP_ECHO &&
1117 icmph->type != ICMP_TIMESTAMP &&
1118 icmph->type != ICMP_ADDRESS &&
1119 icmph->type != ICMP_ADDRESSREPLY) {
1120 goto error;
1121 }
1122 }
1123
1124 success = icmp_pointers[icmph->type].handler(skb);
1125
1126 if (success) {
1127 consume_skb(skb);
1128 return NET_RX_SUCCESS;
1129 }
1130
1131 drop:
1132 kfree_skb(skb);
1133 return NET_RX_DROP;
1134 csum_error:
1135 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1136 error:
1137 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1138 goto drop;
1139 }
1140
1141 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1142 {
1143 struct icmp_extobj_hdr *objh, _objh;
1144 struct icmp_ext_hdr *exth, _exth;
1145 u16 olen;
1146
1147 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1148 if (!exth)
1149 return false;
1150 if (exth->version != 2)
1151 return true;
1152
1153 if (exth->checksum &&
1154 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1155 return false;
1156
1157 off += sizeof(_exth);
1158 while (off < skb->len) {
1159 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1160 if (!objh)
1161 return false;
1162
1163 olen = ntohs(objh->length);
1164 if (olen < sizeof(_objh))
1165 return false;
1166
1167 off += olen;
1168 if (off > skb->len)
1169 return false;
1170 }
1171
1172 return true;
1173 }
1174
1175 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1176 struct sock_ee_data_rfc4884 *out,
1177 int thlen, int off)
1178 {
1179 int hlen;
1180
1181 /* original datagram headers: end of icmph to payload (skb->data) */
1182 hlen = -skb_transport_offset(skb) - thlen;
1183
1184 /* per rfc 4884: minimal datagram length of 128 bytes */
1185 if (off < 128 || off < hlen)
1186 return;
1187
1188 /* kernel has stripped headers: return payload offset in bytes */
1189 off -= hlen;
1190 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1191 return;
1192
1193 out->len = off;
1194
1195 if (!ip_icmp_error_rfc4884_validate(skb, off))
1196 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1197 }
1198 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1199
1200 int icmp_err(struct sk_buff *skb, u32 info)
1201 {
1202 struct iphdr *iph = (struct iphdr *)skb->data;
1203 int offset = iph->ihl<<2;
1204 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1205 int type = icmp_hdr(skb)->type;
1206 int code = icmp_hdr(skb)->code;
1207 struct net *net = dev_net(skb->dev);
1208
1209 /*
1210 * Use ping_err to handle all icmp errors except those
1211 * triggered by ICMP_ECHOREPLY which sent from kernel.
1212 */
1213 if (icmph->type != ICMP_ECHOREPLY) {
1214 ping_err(skb, offset, info);
1215 return 0;
1216 }
1217
1218 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1219 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1220 else if (type == ICMP_REDIRECT)
1221 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1222
1223 return 0;
1224 }
1225
1226 /*
1227 * This table is the definition of how we handle ICMP.
1228 */
1229 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1230 [ICMP_ECHOREPLY] = {
1231 .handler = ping_rcv,
1232 },
1233 [1] = {
1234 .handler = icmp_discard,
1235 .error = 1,
1236 },
1237 [2] = {
1238 .handler = icmp_discard,
1239 .error = 1,
1240 },
1241 [ICMP_DEST_UNREACH] = {
1242 .handler = icmp_unreach,
1243 .error = 1,
1244 },
1245 [ICMP_SOURCE_QUENCH] = {
1246 .handler = icmp_unreach,
1247 .error = 1,
1248 },
1249 [ICMP_REDIRECT] = {
1250 .handler = icmp_redirect,
1251 .error = 1,
1252 },
1253 [6] = {
1254 .handler = icmp_discard,
1255 .error = 1,
1256 },
1257 [7] = {
1258 .handler = icmp_discard,
1259 .error = 1,
1260 },
1261 [ICMP_ECHO] = {
1262 .handler = icmp_echo,
1263 },
1264 [9] = {
1265 .handler = icmp_discard,
1266 .error = 1,
1267 },
1268 [10] = {
1269 .handler = icmp_discard,
1270 .error = 1,
1271 },
1272 [ICMP_TIME_EXCEEDED] = {
1273 .handler = icmp_unreach,
1274 .error = 1,
1275 },
1276 [ICMP_PARAMETERPROB] = {
1277 .handler = icmp_unreach,
1278 .error = 1,
1279 },
1280 [ICMP_TIMESTAMP] = {
1281 .handler = icmp_timestamp,
1282 },
1283 [ICMP_TIMESTAMPREPLY] = {
1284 .handler = icmp_discard,
1285 },
1286 [ICMP_INFO_REQUEST] = {
1287 .handler = icmp_discard,
1288 },
1289 [ICMP_INFO_REPLY] = {
1290 .handler = icmp_discard,
1291 },
1292 [ICMP_ADDRESS] = {
1293 .handler = icmp_discard,
1294 },
1295 [ICMP_ADDRESSREPLY] = {
1296 .handler = icmp_discard,
1297 },
1298 };
1299
1300 static void __net_exit icmp_sk_exit(struct net *net)
1301 {
1302 int i;
1303
1304 for_each_possible_cpu(i)
1305 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1306 free_percpu(net->ipv4.icmp_sk);
1307 net->ipv4.icmp_sk = NULL;
1308 }
1309
1310 static int __net_init icmp_sk_init(struct net *net)
1311 {
1312 int i, err;
1313
1314 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1315 if (!net->ipv4.icmp_sk)
1316 return -ENOMEM;
1317
1318 for_each_possible_cpu(i) {
1319 struct sock *sk;
1320
1321 err = inet_ctl_sock_create(&sk, PF_INET,
1322 SOCK_RAW, IPPROTO_ICMP, net);
1323 if (err < 0)
1324 goto fail;
1325
1326 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1327
1328 /* Enough space for 2 64K ICMP packets, including
1329 * sk_buff/skb_shared_info struct overhead.
1330 */
1331 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1332
1333 /*
1334 * Speedup sock_wfree()
1335 */
1336 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1337 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1338 }
1339
1340 /* Control parameters for ECHO replies. */
1341 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1342 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1343
1344 /* Control parameter - ignore bogus broadcast responses? */
1345 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1346
1347 /*
1348 * Configurable global rate limit.
1349 *
1350 * ratelimit defines tokens/packet consumed for dst->rate_token
1351 * bucket ratemask defines which icmp types are ratelimited by
1352 * setting it's bit position.
1353 *
1354 * default:
1355 * dest unreachable (3), source quench (4),
1356 * time exceeded (11), parameter problem (12)
1357 */
1358
1359 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1360 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1361 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1362
1363 return 0;
1364
1365 fail:
1366 icmp_sk_exit(net);
1367 return err;
1368 }
1369
1370 static struct pernet_operations __net_initdata icmp_sk_ops = {
1371 .init = icmp_sk_init,
1372 .exit = icmp_sk_exit,
1373 };
1374
1375 int __init icmp_init(void)
1376 {
1377 return register_pernet_subsys(&icmp_sk_ops);
1378 }
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