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 */
icmp_sk(struct net * net)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 */
icmp_xmit_lock(struct net * net)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
icmp_xmit_unlock(struct sock * sk)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 */
icmp_global_allow(void)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
icmpv4_mask_allow(struct net * net,int type,int code)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
icmpv4_global_allow(struct net * net,int type,int code)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
icmpv4_xrlim_allow(struct net * net,struct rtable * rt,struct flowi4 * fl4,int type,int code)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 */
icmp_out_count(struct net * net,unsigned char type)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 */
icmp_glue_bits(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)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
icmp_push_reply(struct icmp_bxm * icmp_param,struct flowi4 * fl4,struct ipcm_cookie * ipc,struct rtable ** rt)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
icmp_reply(struct icmp_bxm * icmp_param,struct sk_buff * skb)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_common(&fl4));
451 rt = ip_route_output_key(net, &fl4);
452 if (IS_ERR(rt))
453 goto out_unlock;
454 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
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 */
icmp_get_route_lookup_dev(struct sk_buff * skb)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
icmp_route_lookup(struct net * net,struct flowi4 * fl4,struct sk_buff * skb_in,const struct iphdr * iph,__be32 saddr,u8 tos,u32 mark,int type,int code,struct icmp_bxm * param)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_common(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
__icmp_send(struct sk_buff * skb_in,int type,int code,__be32 info,const struct ip_options * opt)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>
icmp_ndo_send(struct sk_buff * skb_in,int type,int code,__be32 info)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 struct ip_options opts = { 0 };
779 enum ip_conntrack_info ctinfo;
780 struct nf_conn *ct;
781 __be32 orig_ip;
782
783 ct = nf_ct_get(skb_in, &ctinfo);
784 if (!ct || !(ct->status & IPS_SRC_NAT)) {
785 __icmp_send(skb_in, type, code, info, &opts);
786 return;
787 }
788
789 if (skb_shared(skb_in))
790 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
791
792 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
793 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
794 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
795 skb_network_offset(skb_in) + sizeof(struct iphdr))))
796 goto out;
797
798 orig_ip = ip_hdr(skb_in)->saddr;
799 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
800 __icmp_send(skb_in, type, code, info, &opts);
801 ip_hdr(skb_in)->saddr = orig_ip;
802 out:
803 consume_skb(cloned_skb);
804 }
805 EXPORT_SYMBOL(icmp_ndo_send);
806 #endif
807
icmp_socket_deliver(struct sk_buff * skb,u32 info)808 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
809 {
810 const struct iphdr *iph = (const struct iphdr *)skb->data;
811 const struct net_protocol *ipprot;
812 int protocol = iph->protocol;
813
814 /* Checkin full IP header plus 8 bytes of protocol to
815 * avoid additional coding at protocol handlers.
816 */
817 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
818 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
819 return;
820 }
821
822 raw_icmp_error(skb, protocol, info);
823
824 ipprot = rcu_dereference(inet_protos[protocol]);
825 if (ipprot && ipprot->err_handler)
826 ipprot->err_handler(skb, info);
827 }
828
icmp_tag_validation(int proto)829 static bool icmp_tag_validation(int proto)
830 {
831 bool ok;
832
833 rcu_read_lock();
834 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
835 rcu_read_unlock();
836 return ok;
837 }
838
839 /*
840 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
841 * ICMP_PARAMETERPROB.
842 */
843
icmp_unreach(struct sk_buff * skb)844 static bool icmp_unreach(struct sk_buff *skb)
845 {
846 const struct iphdr *iph;
847 struct icmphdr *icmph;
848 struct net *net;
849 u32 info = 0;
850
851 net = dev_net(skb_dst(skb)->dev);
852
853 /*
854 * Incomplete header ?
855 * Only checks for the IP header, there should be an
856 * additional check for longer headers in upper levels.
857 */
858
859 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
860 goto out_err;
861
862 icmph = icmp_hdr(skb);
863 iph = (const struct iphdr *)skb->data;
864
865 if (iph->ihl < 5) /* Mangled header, drop. */
866 goto out_err;
867
868 switch (icmph->type) {
869 case ICMP_DEST_UNREACH:
870 switch (icmph->code & 15) {
871 case ICMP_NET_UNREACH:
872 case ICMP_HOST_UNREACH:
873 case ICMP_PROT_UNREACH:
874 case ICMP_PORT_UNREACH:
875 break;
876 case ICMP_FRAG_NEEDED:
877 /* for documentation of the ip_no_pmtu_disc
878 * values please see
879 * Documentation/networking/ip-sysctl.rst
880 */
881 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
882 default:
883 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
884 &iph->daddr);
885 break;
886 case 2:
887 goto out;
888 case 3:
889 if (!icmp_tag_validation(iph->protocol))
890 goto out;
891 fallthrough;
892 case 0:
893 info = ntohs(icmph->un.frag.mtu);
894 }
895 break;
896 case ICMP_SR_FAILED:
897 net_dbg_ratelimited("%pI4: Source Route Failed\n",
898 &iph->daddr);
899 break;
900 default:
901 break;
902 }
903 if (icmph->code > NR_ICMP_UNREACH)
904 goto out;
905 break;
906 case ICMP_PARAMETERPROB:
907 info = ntohl(icmph->un.gateway) >> 24;
908 break;
909 case ICMP_TIME_EXCEEDED:
910 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
911 if (icmph->code == ICMP_EXC_FRAGTIME)
912 goto out;
913 break;
914 }
915
916 /*
917 * Throw it at our lower layers
918 *
919 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
920 * header.
921 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
922 * transport layer.
923 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
924 * transport layer.
925 */
926
927 /*
928 * Check the other end isn't violating RFC 1122. Some routers send
929 * bogus responses to broadcast frames. If you see this message
930 * first check your netmask matches at both ends, if it does then
931 * get the other vendor to fix their kit.
932 */
933
934 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
935 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
936 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
937 &ip_hdr(skb)->saddr,
938 icmph->type, icmph->code,
939 &iph->daddr, skb->dev->name);
940 goto out;
941 }
942
943 icmp_socket_deliver(skb, info);
944
945 out:
946 return true;
947 out_err:
948 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
949 return false;
950 }
951
952
953 /*
954 * Handle ICMP_REDIRECT.
955 */
956
icmp_redirect(struct sk_buff * skb)957 static bool icmp_redirect(struct sk_buff *skb)
958 {
959 if (skb->len < sizeof(struct iphdr)) {
960 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
961 return false;
962 }
963
964 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
965 /* there aught to be a stat */
966 return false;
967 }
968
969 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
970 return true;
971 }
972
973 /*
974 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
975 *
976 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
977 * requests.
978 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
979 * included in the reply.
980 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
981 * echo requests, MUST have default=NOT.
982 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
983 * Extended Echo Functionality, MUST be disabled by default
984 * See also WRT handling of options once they are done and working.
985 */
986
icmp_echo(struct sk_buff * skb)987 static bool icmp_echo(struct sk_buff *skb)
988 {
989 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
990 struct icmp_ext_echo_iio *iio, _iio;
991 struct icmp_bxm icmp_param;
992 struct net_device *dev;
993 char buff[IFNAMSIZ];
994 struct net *net;
995 u16 ident_len;
996 u8 status;
997
998 net = dev_net(skb_dst(skb)->dev);
999 /* should there be an ICMP stat for ignored echos? */
1000 if (net->ipv4.sysctl_icmp_echo_ignore_all)
1001 return true;
1002
1003 icmp_param.data.icmph = *icmp_hdr(skb);
1004 icmp_param.skb = skb;
1005 icmp_param.offset = 0;
1006 icmp_param.data_len = skb->len;
1007 icmp_param.head_len = sizeof(struct icmphdr);
1008
1009 if (icmp_param.data.icmph.type == ICMP_ECHO) {
1010 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1011 goto send_reply;
1012 }
1013 if (!net->ipv4.sysctl_icmp_echo_enable_probe)
1014 return true;
1015 /* We currently only support probing interfaces on the proxy node
1016 * Check to ensure L-bit is set
1017 */
1018 if (!(ntohs(icmp_param.data.icmph.un.echo.sequence) & 1))
1019 return true;
1020 /* Clear status bits in reply message */
1021 icmp_param.data.icmph.un.echo.sequence &= htons(0xFF00);
1022 icmp_param.data.icmph.type = ICMP_EXT_ECHOREPLY;
1023 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1024 /* Size of iio is class_type dependent.
1025 * Only check header here and assign length based on ctype in the switch statement
1026 */
1027 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1028 if (!ext_hdr || !iio)
1029 goto send_mal_query;
1030 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr))
1031 goto send_mal_query;
1032 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1033 status = 0;
1034 dev = NULL;
1035 switch (iio->extobj_hdr.class_type) {
1036 case ICMP_EXT_ECHO_CTYPE_NAME:
1037 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(_iio), &_iio);
1038 if (ident_len >= IFNAMSIZ)
1039 goto send_mal_query;
1040 memset(buff, 0, sizeof(buff));
1041 memcpy(buff, &iio->ident.name, ident_len);
1042 dev = dev_get_by_name(net, buff);
1043 break;
1044 case ICMP_EXT_ECHO_CTYPE_INDEX:
1045 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr) +
1046 sizeof(iio->ident.ifindex), &_iio);
1047 if (ident_len != sizeof(iio->ident.ifindex))
1048 goto send_mal_query;
1049 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1050 break;
1051 case ICMP_EXT_ECHO_CTYPE_ADDR:
1052 if (ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1053 iio->ident.addr.ctype3_hdr.addrlen)
1054 goto send_mal_query;
1055 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1056 case ICMP_AFI_IP:
1057 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr) +
1058 sizeof(struct in_addr), &_iio);
1059 if (ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1060 sizeof(struct in_addr))
1061 goto send_mal_query;
1062 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr.s_addr);
1063 break;
1064 #if IS_ENABLED(CONFIG_IPV6)
1065 case ICMP_AFI_IP6:
1066 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(_iio), &_iio);
1067 if (ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1068 sizeof(struct in6_addr))
1069 goto send_mal_query;
1070 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1071 if (dev)
1072 dev_hold(dev);
1073 break;
1074 #endif
1075 default:
1076 goto send_mal_query;
1077 }
1078 break;
1079 default:
1080 goto send_mal_query;
1081 }
1082 if (!dev) {
1083 icmp_param.data.icmph.code = ICMP_EXT_CODE_NO_IF;
1084 goto send_reply;
1085 }
1086 /* Fill bits in reply message */
1087 if (dev->flags & IFF_UP)
1088 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1089 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1090 status |= ICMP_EXT_ECHOREPLY_IPV4;
1091 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1092 status |= ICMP_EXT_ECHOREPLY_IPV6;
1093 dev_put(dev);
1094 icmp_param.data.icmph.un.echo.sequence |= htons(status);
1095 send_reply:
1096 icmp_reply(&icmp_param, skb);
1097 return true;
1098 send_mal_query:
1099 icmp_param.data.icmph.code = ICMP_EXT_CODE_MAL_QUERY;
1100 goto send_reply;
1101 }
1102
1103 /*
1104 * Handle ICMP Timestamp requests.
1105 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1106 * SHOULD be in the kernel for minimum random latency.
1107 * MUST be accurate to a few minutes.
1108 * MUST be updated at least at 15Hz.
1109 */
icmp_timestamp(struct sk_buff * skb)1110 static bool icmp_timestamp(struct sk_buff *skb)
1111 {
1112 struct icmp_bxm icmp_param;
1113 /*
1114 * Too short.
1115 */
1116 if (skb->len < 4)
1117 goto out_err;
1118
1119 /*
1120 * Fill in the current time as ms since midnight UT:
1121 */
1122 icmp_param.data.times[1] = inet_current_timestamp();
1123 icmp_param.data.times[2] = icmp_param.data.times[1];
1124
1125 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1126
1127 icmp_param.data.icmph = *icmp_hdr(skb);
1128 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1129 icmp_param.data.icmph.code = 0;
1130 icmp_param.skb = skb;
1131 icmp_param.offset = 0;
1132 icmp_param.data_len = 0;
1133 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1134 icmp_reply(&icmp_param, skb);
1135 return true;
1136
1137 out_err:
1138 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1139 return false;
1140 }
1141
icmp_discard(struct sk_buff * skb)1142 static bool icmp_discard(struct sk_buff *skb)
1143 {
1144 /* pretend it was a success */
1145 return true;
1146 }
1147
1148 /*
1149 * Deal with incoming ICMP packets.
1150 */
icmp_rcv(struct sk_buff * skb)1151 int icmp_rcv(struct sk_buff *skb)
1152 {
1153 struct icmphdr *icmph;
1154 struct rtable *rt = skb_rtable(skb);
1155 struct net *net = dev_net(rt->dst.dev);
1156 bool success;
1157
1158 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1159 struct sec_path *sp = skb_sec_path(skb);
1160 int nh;
1161
1162 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1163 XFRM_STATE_ICMP))
1164 goto drop;
1165
1166 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1167 goto drop;
1168
1169 nh = skb_network_offset(skb);
1170 skb_set_network_header(skb, sizeof(*icmph));
1171
1172 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1173 goto drop;
1174
1175 skb_set_network_header(skb, nh);
1176 }
1177
1178 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1179
1180 if (skb_checksum_simple_validate(skb))
1181 goto csum_error;
1182
1183 if (!pskb_pull(skb, sizeof(*icmph)))
1184 goto error;
1185
1186 icmph = icmp_hdr(skb);
1187
1188 ICMPMSGIN_INC_STATS(net, icmph->type);
1189
1190 /* Check for ICMP Extended Echo (PROBE) messages */
1191 if (icmph->type == ICMP_EXT_ECHO) {
1192 /* We can't use icmp_pointers[].handler() because it is an array of
1193 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1194 */
1195 success = icmp_echo(skb);
1196 goto success_check;
1197 }
1198
1199 if (icmph->type == ICMP_EXT_ECHOREPLY) {
1200 success = ping_rcv(skb);
1201 goto success_check;
1202 }
1203
1204 /*
1205 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1206 *
1207 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1208 * discarded.
1209 */
1210 if (icmph->type > NR_ICMP_TYPES)
1211 goto error;
1212
1213 /*
1214 * Parse the ICMP message
1215 */
1216
1217 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1218 /*
1219 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1220 * silently ignored (we let user decide with a sysctl).
1221 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1222 * discarded if to broadcast/multicast.
1223 */
1224 if ((icmph->type == ICMP_ECHO ||
1225 icmph->type == ICMP_TIMESTAMP) &&
1226 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1227 goto error;
1228 }
1229 if (icmph->type != ICMP_ECHO &&
1230 icmph->type != ICMP_TIMESTAMP &&
1231 icmph->type != ICMP_ADDRESS &&
1232 icmph->type != ICMP_ADDRESSREPLY) {
1233 goto error;
1234 }
1235 }
1236
1237 success = icmp_pointers[icmph->type].handler(skb);
1238 success_check:
1239 if (success) {
1240 consume_skb(skb);
1241 return NET_RX_SUCCESS;
1242 }
1243
1244 drop:
1245 kfree_skb(skb);
1246 return NET_RX_DROP;
1247 csum_error:
1248 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1249 error:
1250 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1251 goto drop;
1252 }
1253
ip_icmp_error_rfc4884_validate(const struct sk_buff * skb,int off)1254 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1255 {
1256 struct icmp_extobj_hdr *objh, _objh;
1257 struct icmp_ext_hdr *exth, _exth;
1258 u16 olen;
1259
1260 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1261 if (!exth)
1262 return false;
1263 if (exth->version != 2)
1264 return true;
1265
1266 if (exth->checksum &&
1267 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1268 return false;
1269
1270 off += sizeof(_exth);
1271 while (off < skb->len) {
1272 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1273 if (!objh)
1274 return false;
1275
1276 olen = ntohs(objh->length);
1277 if (olen < sizeof(_objh))
1278 return false;
1279
1280 off += olen;
1281 if (off > skb->len)
1282 return false;
1283 }
1284
1285 return true;
1286 }
1287
ip_icmp_error_rfc4884(const struct sk_buff * skb,struct sock_ee_data_rfc4884 * out,int thlen,int off)1288 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1289 struct sock_ee_data_rfc4884 *out,
1290 int thlen, int off)
1291 {
1292 int hlen;
1293
1294 /* original datagram headers: end of icmph to payload (skb->data) */
1295 hlen = -skb_transport_offset(skb) - thlen;
1296
1297 /* per rfc 4884: minimal datagram length of 128 bytes */
1298 if (off < 128 || off < hlen)
1299 return;
1300
1301 /* kernel has stripped headers: return payload offset in bytes */
1302 off -= hlen;
1303 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1304 return;
1305
1306 out->len = off;
1307
1308 if (!ip_icmp_error_rfc4884_validate(skb, off))
1309 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1310 }
1311 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1312
icmp_err(struct sk_buff * skb,u32 info)1313 int icmp_err(struct sk_buff *skb, u32 info)
1314 {
1315 struct iphdr *iph = (struct iphdr *)skb->data;
1316 int offset = iph->ihl<<2;
1317 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1318 int type = icmp_hdr(skb)->type;
1319 int code = icmp_hdr(skb)->code;
1320 struct net *net = dev_net(skb->dev);
1321
1322 /*
1323 * Use ping_err to handle all icmp errors except those
1324 * triggered by ICMP_ECHOREPLY which sent from kernel.
1325 */
1326 if (icmph->type != ICMP_ECHOREPLY) {
1327 ping_err(skb, offset, info);
1328 return 0;
1329 }
1330
1331 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1332 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1333 else if (type == ICMP_REDIRECT)
1334 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1335
1336 return 0;
1337 }
1338
1339 /*
1340 * This table is the definition of how we handle ICMP.
1341 */
1342 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1343 [ICMP_ECHOREPLY] = {
1344 .handler = ping_rcv,
1345 },
1346 [1] = {
1347 .handler = icmp_discard,
1348 .error = 1,
1349 },
1350 [2] = {
1351 .handler = icmp_discard,
1352 .error = 1,
1353 },
1354 [ICMP_DEST_UNREACH] = {
1355 .handler = icmp_unreach,
1356 .error = 1,
1357 },
1358 [ICMP_SOURCE_QUENCH] = {
1359 .handler = icmp_unreach,
1360 .error = 1,
1361 },
1362 [ICMP_REDIRECT] = {
1363 .handler = icmp_redirect,
1364 .error = 1,
1365 },
1366 [6] = {
1367 .handler = icmp_discard,
1368 .error = 1,
1369 },
1370 [7] = {
1371 .handler = icmp_discard,
1372 .error = 1,
1373 },
1374 [ICMP_ECHO] = {
1375 .handler = icmp_echo,
1376 },
1377 [9] = {
1378 .handler = icmp_discard,
1379 .error = 1,
1380 },
1381 [10] = {
1382 .handler = icmp_discard,
1383 .error = 1,
1384 },
1385 [ICMP_TIME_EXCEEDED] = {
1386 .handler = icmp_unreach,
1387 .error = 1,
1388 },
1389 [ICMP_PARAMETERPROB] = {
1390 .handler = icmp_unreach,
1391 .error = 1,
1392 },
1393 [ICMP_TIMESTAMP] = {
1394 .handler = icmp_timestamp,
1395 },
1396 [ICMP_TIMESTAMPREPLY] = {
1397 .handler = icmp_discard,
1398 },
1399 [ICMP_INFO_REQUEST] = {
1400 .handler = icmp_discard,
1401 },
1402 [ICMP_INFO_REPLY] = {
1403 .handler = icmp_discard,
1404 },
1405 [ICMP_ADDRESS] = {
1406 .handler = icmp_discard,
1407 },
1408 [ICMP_ADDRESSREPLY] = {
1409 .handler = icmp_discard,
1410 },
1411 };
1412
icmp_sk_exit(struct net * net)1413 static void __net_exit icmp_sk_exit(struct net *net)
1414 {
1415 int i;
1416
1417 for_each_possible_cpu(i)
1418 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1419 free_percpu(net->ipv4.icmp_sk);
1420 net->ipv4.icmp_sk = NULL;
1421 }
1422
icmp_sk_init(struct net * net)1423 static int __net_init icmp_sk_init(struct net *net)
1424 {
1425 int i, err;
1426
1427 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1428 if (!net->ipv4.icmp_sk)
1429 return -ENOMEM;
1430
1431 for_each_possible_cpu(i) {
1432 struct sock *sk;
1433
1434 err = inet_ctl_sock_create(&sk, PF_INET,
1435 SOCK_RAW, IPPROTO_ICMP, net);
1436 if (err < 0)
1437 goto fail;
1438
1439 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1440
1441 /* Enough space for 2 64K ICMP packets, including
1442 * sk_buff/skb_shared_info struct overhead.
1443 */
1444 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1445
1446 /*
1447 * Speedup sock_wfree()
1448 */
1449 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1450 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1451 }
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 fail:
1480 icmp_sk_exit(net);
1481 return err;
1482 }
1483
1484 static struct pernet_operations __net_initdata icmp_sk_ops = {
1485 .init = icmp_sk_init,
1486 .exit = icmp_sk_exit,
1487 };
1488
icmp_init(void)1489 int __init icmp_init(void)
1490 {
1491 return register_pernet_subsys(&icmp_sk_ops);
1492 }
1493