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Remove obsolete #include <linux/config.h>
[mirror_ubuntu-jammy-kernel.git] / net / ipv4 / icmp.c
1 /*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@redhat.com>
5 *
6 * Version: $Id: icmp.c,v 1.85 2002/02/01 22:01:03 davem Exp $
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 *
13 * Some of the function names and the icmp unreach table for this
14 * module were derived from [icmp.c 1.0.11 06/02/93] by
15 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
16 * Other than that this module is a complete rewrite.
17 *
18 * Fixes:
19 * Clemens Fruhwirth : introduce global icmp rate limiting
20 * with icmp type masking ability instead
21 * of broken per type icmp timeouts.
22 * Mike Shaver : RFC1122 checks.
23 * Alan Cox : Multicast ping reply as self.
24 * Alan Cox : Fix atomicity lockup in ip_build_xmit
25 * call.
26 * Alan Cox : Added 216,128 byte paths to the MTU
27 * code.
28 * Martin Mares : RFC1812 checks.
29 * Martin Mares : Can be configured to follow redirects
30 * if acting as a router _without_ a
31 * routing protocol (RFC 1812).
32 * Martin Mares : Echo requests may be configured to
33 * be ignored (RFC 1812).
34 * Martin Mares : Limitation of ICMP error message
35 * transmit rate (RFC 1812).
36 * Martin Mares : TOS and Precedence set correctly
37 * (RFC 1812).
38 * Martin Mares : Now copying as much data from the
39 * original packet as we can without
40 * exceeding 576 bytes (RFC 1812).
41 * Willy Konynenberg : Transparent proxying support.
42 * Keith Owens : RFC1191 correction for 4.2BSD based
43 * path MTU bug.
44 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
45 * valid (RFC 1812).
46 * Andi Kleen : Check all packet lengths properly
47 * and moved all kfree_skb() up to
48 * icmp_rcv.
49 * Andi Kleen : Move the rate limit bookkeeping
50 * into the dest entry and use a token
51 * bucket filter (thanks to ANK). Make
52 * the rates sysctl configurable.
53 * Yu Tianli : Fixed two ugly bugs in icmp_send
54 * - IP option length was accounted wrongly
55 * - ICMP header length was not accounted
56 * at all.
57 * Tristan Greaves : Added sysctl option to ignore bogus
58 * broadcast responses from broken routers.
59 *
60 * To Fix:
61 *
62 * - Should use skb_pull() instead of all the manual checking.
63 * This would also greatly simply some upper layer error handlers. --AK
64 *
65 */
66
67 #include <linux/module.h>
68 #include <linux/types.h>
69 #include <linux/jiffies.h>
70 #include <linux/kernel.h>
71 #include <linux/fcntl.h>
72 #include <linux/socket.h>
73 #include <linux/in.h>
74 #include <linux/inet.h>
75 #include <linux/inetdevice.h>
76 #include <linux/netdevice.h>
77 #include <linux/string.h>
78 #include <linux/netfilter_ipv4.h>
79 #include <net/snmp.h>
80 #include <net/ip.h>
81 #include <net/route.h>
82 #include <net/protocol.h>
83 #include <net/icmp.h>
84 #include <net/tcp.h>
85 #include <net/udp.h>
86 #include <net/raw.h>
87 #include <linux/skbuff.h>
88 #include <net/sock.h>
89 #include <linux/errno.h>
90 #include <linux/timer.h>
91 #include <linux/init.h>
92 #include <asm/system.h>
93 #include <asm/uaccess.h>
94 #include <net/checksum.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 __u32 times[3];
108 } data;
109 int head_len;
110 struct ip_options replyopts;
111 unsigned char optbuf[40];
112 };
113
114 /*
115 * Statistics
116 */
117 DEFINE_SNMP_STAT(struct icmp_mib, icmp_statistics) __read_mostly;
118
119 /* An array of errno for error messages from dest unreach. */
120 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
121
122 struct icmp_err icmp_err_convert[] = {
123 {
124 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
125 .fatal = 0,
126 },
127 {
128 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
129 .fatal = 0,
130 },
131 {
132 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
133 .fatal = 1,
134 },
135 {
136 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
137 .fatal = 1,
138 },
139 {
140 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
141 .fatal = 0,
142 },
143 {
144 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
145 .fatal = 0,
146 },
147 {
148 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
149 .fatal = 1,
150 },
151 {
152 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
153 .fatal = 1,
154 },
155 {
156 .errno = ENONET, /* ICMP_HOST_ISOLATED */
157 .fatal = 1,
158 },
159 {
160 .errno = ENETUNREACH, /* ICMP_NET_ANO */
161 .fatal = 1,
162 },
163 {
164 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
165 .fatal = 1,
166 },
167 {
168 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
169 .fatal = 0,
170 },
171 {
172 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
173 .fatal = 0,
174 },
175 {
176 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
177 .fatal = 1,
178 },
179 {
180 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
181 .fatal = 1,
182 },
183 {
184 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
185 .fatal = 1,
186 },
187 };
188
189 /* Control parameters for ECHO replies. */
190 int sysctl_icmp_echo_ignore_all;
191 int sysctl_icmp_echo_ignore_broadcasts = 1;
192
193 /* Control parameter - ignore bogus broadcast responses? */
194 int sysctl_icmp_ignore_bogus_error_responses = 1;
195
196 /*
197 * Configurable global rate limit.
198 *
199 * ratelimit defines tokens/packet consumed for dst->rate_token bucket
200 * ratemask defines which icmp types are ratelimited by setting
201 * it's bit position.
202 *
203 * default:
204 * dest unreachable (3), source quench (4),
205 * time exceeded (11), parameter problem (12)
206 */
207
208 int sysctl_icmp_ratelimit = 1 * HZ;
209 int sysctl_icmp_ratemask = 0x1818;
210 int sysctl_icmp_errors_use_inbound_ifaddr;
211
212 /*
213 * ICMP control array. This specifies what to do with each ICMP.
214 */
215
216 struct icmp_control {
217 int output_entry; /* Field for increment on output */
218 int input_entry; /* Field for increment on input */
219 void (*handler)(struct sk_buff *skb);
220 short error; /* This ICMP is classed as an error message */
221 };
222
223 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
224
225 /*
226 * The ICMP socket(s). This is the most convenient way to flow control
227 * our ICMP output as well as maintain a clean interface throughout
228 * all layers. All Socketless IP sends will soon be gone.
229 *
230 * On SMP we have one ICMP socket per-cpu.
231 */
232 static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
233 #define icmp_socket __get_cpu_var(__icmp_socket)
234
235 static __inline__ int icmp_xmit_lock(void)
236 {
237 local_bh_disable();
238
239 if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
240 /* This can happen if the output path signals a
241 * dst_link_failure() for an outgoing ICMP packet.
242 */
243 local_bh_enable();
244 return 1;
245 }
246 return 0;
247 }
248
249 static void icmp_xmit_unlock(void)
250 {
251 spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
252 }
253
254 /*
255 * Send an ICMP frame.
256 */
257
258 /*
259 * Check transmit rate limitation for given message.
260 * The rate information is held in the destination cache now.
261 * This function is generic and could be used for other purposes
262 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov.
263 *
264 * Note that the same dst_entry fields are modified by functions in
265 * route.c too, but these work for packet destinations while xrlim_allow
266 * works for icmp destinations. This means the rate limiting information
267 * for one "ip object" is shared - and these ICMPs are twice limited:
268 * by source and by destination.
269 *
270 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate
271 * SHOULD allow setting of rate limits
272 *
273 * Shared between ICMPv4 and ICMPv6.
274 */
275 #define XRLIM_BURST_FACTOR 6
276 int xrlim_allow(struct dst_entry *dst, int timeout)
277 {
278 unsigned long now;
279 int rc = 0;
280
281 now = jiffies;
282 dst->rate_tokens += now - dst->rate_last;
283 dst->rate_last = now;
284 if (dst->rate_tokens > XRLIM_BURST_FACTOR * timeout)
285 dst->rate_tokens = XRLIM_BURST_FACTOR * timeout;
286 if (dst->rate_tokens >= timeout) {
287 dst->rate_tokens -= timeout;
288 rc = 1;
289 }
290 return rc;
291 }
292
293 static inline int icmpv4_xrlim_allow(struct rtable *rt, int type, int code)
294 {
295 struct dst_entry *dst = &rt->u.dst;
296 int rc = 1;
297
298 if (type > NR_ICMP_TYPES)
299 goto out;
300
301 /* Don't limit PMTU discovery. */
302 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
303 goto out;
304
305 /* No rate limit on loopback */
306 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
307 goto out;
308
309 /* Limit if icmp type is enabled in ratemask. */
310 if ((1 << type) & sysctl_icmp_ratemask)
311 rc = xrlim_allow(dst, sysctl_icmp_ratelimit);
312 out:
313 return rc;
314 }
315
316 /*
317 * Maintain the counters used in the SNMP statistics for outgoing ICMP
318 */
319 static void icmp_out_count(int type)
320 {
321 if (type <= NR_ICMP_TYPES) {
322 ICMP_INC_STATS(icmp_pointers[type].output_entry);
323 ICMP_INC_STATS(ICMP_MIB_OUTMSGS);
324 }
325 }
326
327 /*
328 * Checksum each fragment, and on the first include the headers and final
329 * checksum.
330 */
331 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
332 struct sk_buff *skb)
333 {
334 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
335 unsigned int csum;
336
337 csum = skb_copy_and_csum_bits(icmp_param->skb,
338 icmp_param->offset + offset,
339 to, len, 0);
340
341 skb->csum = csum_block_add(skb->csum, csum, odd);
342 if (icmp_pointers[icmp_param->data.icmph.type].error)
343 nf_ct_attach(skb, icmp_param->skb);
344 return 0;
345 }
346
347 static void icmp_push_reply(struct icmp_bxm *icmp_param,
348 struct ipcm_cookie *ipc, struct rtable *rt)
349 {
350 struct sk_buff *skb;
351
352 if (ip_append_data(icmp_socket->sk, icmp_glue_bits, icmp_param,
353 icmp_param->data_len+icmp_param->head_len,
354 icmp_param->head_len,
355 ipc, rt, MSG_DONTWAIT) < 0)
356 ip_flush_pending_frames(icmp_socket->sk);
357 else if ((skb = skb_peek(&icmp_socket->sk->sk_write_queue)) != NULL) {
358 struct icmphdr *icmph = skb->h.icmph;
359 unsigned int csum = 0;
360 struct sk_buff *skb1;
361
362 skb_queue_walk(&icmp_socket->sk->sk_write_queue, skb1) {
363 csum = csum_add(csum, skb1->csum);
364 }
365 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
366 (char *)icmph,
367 icmp_param->head_len, csum);
368 icmph->checksum = csum_fold(csum);
369 skb->ip_summed = CHECKSUM_NONE;
370 ip_push_pending_frames(icmp_socket->sk);
371 }
372 }
373
374 /*
375 * Driving logic for building and sending ICMP messages.
376 */
377
378 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
379 {
380 struct sock *sk = icmp_socket->sk;
381 struct inet_sock *inet = inet_sk(sk);
382 struct ipcm_cookie ipc;
383 struct rtable *rt = (struct rtable *)skb->dst;
384 u32 daddr;
385
386 if (ip_options_echo(&icmp_param->replyopts, skb))
387 return;
388
389 if (icmp_xmit_lock())
390 return;
391
392 icmp_param->data.icmph.checksum = 0;
393 icmp_out_count(icmp_param->data.icmph.type);
394
395 inet->tos = skb->nh.iph->tos;
396 daddr = ipc.addr = rt->rt_src;
397 ipc.opt = NULL;
398 if (icmp_param->replyopts.optlen) {
399 ipc.opt = &icmp_param->replyopts;
400 if (ipc.opt->srr)
401 daddr = icmp_param->replyopts.faddr;
402 }
403 {
404 struct flowi fl = { .nl_u = { .ip4_u =
405 { .daddr = daddr,
406 .saddr = rt->rt_spec_dst,
407 .tos = RT_TOS(skb->nh.iph->tos) } },
408 .proto = IPPROTO_ICMP };
409 if (ip_route_output_key(&rt, &fl))
410 goto out_unlock;
411 }
412 if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
413 icmp_param->data.icmph.code))
414 icmp_push_reply(icmp_param, &ipc, rt);
415 ip_rt_put(rt);
416 out_unlock:
417 icmp_xmit_unlock();
418 }
419
420
421 /*
422 * Send an ICMP message in response to a situation
423 *
424 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
425 * MAY send more (we do).
426 * MUST NOT change this header information.
427 * MUST NOT reply to a multicast/broadcast IP address.
428 * MUST NOT reply to a multicast/broadcast MAC address.
429 * MUST reply to only the first fragment.
430 */
431
432 void icmp_send(struct sk_buff *skb_in, int type, int code, u32 info)
433 {
434 struct iphdr *iph;
435 int room;
436 struct icmp_bxm icmp_param;
437 struct rtable *rt = (struct rtable *)skb_in->dst;
438 struct ipcm_cookie ipc;
439 u32 saddr;
440 u8 tos;
441
442 if (!rt)
443 goto out;
444
445 /*
446 * Find the original header. It is expected to be valid, of course.
447 * Check this, icmp_send is called from the most obscure devices
448 * sometimes.
449 */
450 iph = skb_in->nh.iph;
451
452 if ((u8 *)iph < skb_in->head || (u8 *)(iph + 1) > skb_in->tail)
453 goto out;
454
455 /*
456 * No replies to physical multicast/broadcast
457 */
458 if (skb_in->pkt_type != PACKET_HOST)
459 goto out;
460
461 /*
462 * Now check at the protocol level
463 */
464 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
465 goto out;
466
467 /*
468 * Only reply to fragment 0. We byte re-order the constant
469 * mask for efficiency.
470 */
471 if (iph->frag_off & htons(IP_OFFSET))
472 goto out;
473
474 /*
475 * If we send an ICMP error to an ICMP error a mess would result..
476 */
477 if (icmp_pointers[type].error) {
478 /*
479 * We are an error, check if we are replying to an
480 * ICMP error
481 */
482 if (iph->protocol == IPPROTO_ICMP) {
483 u8 _inner_type, *itp;
484
485 itp = skb_header_pointer(skb_in,
486 skb_in->nh.raw +
487 (iph->ihl << 2) +
488 offsetof(struct icmphdr,
489 type) -
490 skb_in->data,
491 sizeof(_inner_type),
492 &_inner_type);
493 if (itp == NULL)
494 goto out;
495
496 /*
497 * Assume any unknown ICMP type is an error. This
498 * isn't specified by the RFC, but think about it..
499 */
500 if (*itp > NR_ICMP_TYPES ||
501 icmp_pointers[*itp].error)
502 goto out;
503 }
504 }
505
506 if (icmp_xmit_lock())
507 return;
508
509 /*
510 * Construct source address and options.
511 */
512
513 saddr = iph->daddr;
514 if (!(rt->rt_flags & RTCF_LOCAL)) {
515 if (sysctl_icmp_errors_use_inbound_ifaddr)
516 saddr = inet_select_addr(skb_in->dev, 0, RT_SCOPE_LINK);
517 else
518 saddr = 0;
519 }
520
521 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
522 IPTOS_PREC_INTERNETCONTROL) :
523 iph->tos;
524
525 if (ip_options_echo(&icmp_param.replyopts, skb_in))
526 goto out_unlock;
527
528
529 /*
530 * Prepare data for ICMP header.
531 */
532
533 icmp_param.data.icmph.type = type;
534 icmp_param.data.icmph.code = code;
535 icmp_param.data.icmph.un.gateway = info;
536 icmp_param.data.icmph.checksum = 0;
537 icmp_param.skb = skb_in;
538 icmp_param.offset = skb_in->nh.raw - skb_in->data;
539 icmp_out_count(icmp_param.data.icmph.type);
540 inet_sk(icmp_socket->sk)->tos = tos;
541 ipc.addr = iph->saddr;
542 ipc.opt = &icmp_param.replyopts;
543
544 {
545 struct flowi fl = {
546 .nl_u = {
547 .ip4_u = {
548 .daddr = icmp_param.replyopts.srr ?
549 icmp_param.replyopts.faddr :
550 iph->saddr,
551 .saddr = saddr,
552 .tos = RT_TOS(tos)
553 }
554 },
555 .proto = IPPROTO_ICMP,
556 .uli_u = {
557 .icmpt = {
558 .type = type,
559 .code = code
560 }
561 }
562 };
563 if (ip_route_output_key(&rt, &fl))
564 goto out_unlock;
565 }
566
567 if (!icmpv4_xrlim_allow(rt, type, code))
568 goto ende;
569
570 /* RFC says return as much as we can without exceeding 576 bytes. */
571
572 room = dst_mtu(&rt->u.dst);
573 if (room > 576)
574 room = 576;
575 room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen;
576 room -= sizeof(struct icmphdr);
577
578 icmp_param.data_len = skb_in->len - icmp_param.offset;
579 if (icmp_param.data_len > room)
580 icmp_param.data_len = room;
581 icmp_param.head_len = sizeof(struct icmphdr);
582
583 icmp_push_reply(&icmp_param, &ipc, rt);
584 ende:
585 ip_rt_put(rt);
586 out_unlock:
587 icmp_xmit_unlock();
588 out:;
589 }
590
591
592 /*
593 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
594 */
595
596 static void icmp_unreach(struct sk_buff *skb)
597 {
598 struct iphdr *iph;
599 struct icmphdr *icmph;
600 int hash, protocol;
601 struct net_protocol *ipprot;
602 struct sock *raw_sk;
603 u32 info = 0;
604
605 /*
606 * Incomplete header ?
607 * Only checks for the IP header, there should be an
608 * additional check for longer headers in upper levels.
609 */
610
611 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
612 goto out_err;
613
614 icmph = skb->h.icmph;
615 iph = (struct iphdr *)skb->data;
616
617 if (iph->ihl < 5) /* Mangled header, drop. */
618 goto out_err;
619
620 if (icmph->type == ICMP_DEST_UNREACH) {
621 switch (icmph->code & 15) {
622 case ICMP_NET_UNREACH:
623 case ICMP_HOST_UNREACH:
624 case ICMP_PROT_UNREACH:
625 case ICMP_PORT_UNREACH:
626 break;
627 case ICMP_FRAG_NEEDED:
628 if (ipv4_config.no_pmtu_disc) {
629 LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: "
630 "fragmentation needed "
631 "and DF set.\n",
632 NIPQUAD(iph->daddr));
633 } else {
634 info = ip_rt_frag_needed(iph,
635 ntohs(icmph->un.frag.mtu));
636 if (!info)
637 goto out;
638 }
639 break;
640 case ICMP_SR_FAILED:
641 LIMIT_NETDEBUG(KERN_INFO "ICMP: %u.%u.%u.%u: Source "
642 "Route Failed.\n",
643 NIPQUAD(iph->daddr));
644 break;
645 default:
646 break;
647 }
648 if (icmph->code > NR_ICMP_UNREACH)
649 goto out;
650 } else if (icmph->type == ICMP_PARAMETERPROB)
651 info = ntohl(icmph->un.gateway) >> 24;
652
653 /*
654 * Throw it at our lower layers
655 *
656 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
657 * header.
658 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
659 * transport layer.
660 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
661 * transport layer.
662 */
663
664 /*
665 * Check the other end isnt violating RFC 1122. Some routers send
666 * bogus responses to broadcast frames. If you see this message
667 * first check your netmask matches at both ends, if it does then
668 * get the other vendor to fix their kit.
669 */
670
671 if (!sysctl_icmp_ignore_bogus_error_responses &&
672 inet_addr_type(iph->daddr) == RTN_BROADCAST) {
673 if (net_ratelimit())
674 printk(KERN_WARNING "%u.%u.%u.%u sent an invalid ICMP "
675 "type %u, code %u "
676 "error to a broadcast: %u.%u.%u.%u on %s\n",
677 NIPQUAD(skb->nh.iph->saddr),
678 icmph->type, icmph->code,
679 NIPQUAD(iph->daddr),
680 skb->dev->name);
681 goto out;
682 }
683
684 /* Checkin full IP header plus 8 bytes of protocol to
685 * avoid additional coding at protocol handlers.
686 */
687 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
688 goto out;
689
690 iph = (struct iphdr *)skb->data;
691 protocol = iph->protocol;
692
693 /*
694 * Deliver ICMP message to raw sockets. Pretty useless feature?
695 */
696
697 /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */
698 hash = protocol & (MAX_INET_PROTOS - 1);
699 read_lock(&raw_v4_lock);
700 if ((raw_sk = sk_head(&raw_v4_htable[hash])) != NULL) {
701 while ((raw_sk = __raw_v4_lookup(raw_sk, protocol, iph->daddr,
702 iph->saddr,
703 skb->dev->ifindex)) != NULL) {
704 raw_err(raw_sk, skb, info);
705 raw_sk = sk_next(raw_sk);
706 iph = (struct iphdr *)skb->data;
707 }
708 }
709 read_unlock(&raw_v4_lock);
710
711 rcu_read_lock();
712 ipprot = rcu_dereference(inet_protos[hash]);
713 if (ipprot && ipprot->err_handler)
714 ipprot->err_handler(skb, info);
715 rcu_read_unlock();
716
717 out:
718 return;
719 out_err:
720 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
721 goto out;
722 }
723
724
725 /*
726 * Handle ICMP_REDIRECT.
727 */
728
729 static void icmp_redirect(struct sk_buff *skb)
730 {
731 struct iphdr *iph;
732
733 if (skb->len < sizeof(struct iphdr))
734 goto out_err;
735
736 /*
737 * Get the copied header of the packet that caused the redirect
738 */
739 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
740 goto out;
741
742 iph = (struct iphdr *)skb->data;
743
744 switch (skb->h.icmph->code & 7) {
745 case ICMP_REDIR_NET:
746 case ICMP_REDIR_NETTOS:
747 /*
748 * As per RFC recommendations now handle it as a host redirect.
749 */
750 case ICMP_REDIR_HOST:
751 case ICMP_REDIR_HOSTTOS:
752 ip_rt_redirect(skb->nh.iph->saddr, iph->daddr,
753 skb->h.icmph->un.gateway,
754 iph->saddr, skb->dev);
755 break;
756 }
757 out:
758 return;
759 out_err:
760 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
761 goto out;
762 }
763
764 /*
765 * Handle ICMP_ECHO ("ping") requests.
766 *
767 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
768 * requests.
769 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
770 * included in the reply.
771 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
772 * echo requests, MUST have default=NOT.
773 * See also WRT handling of options once they are done and working.
774 */
775
776 static void icmp_echo(struct sk_buff *skb)
777 {
778 if (!sysctl_icmp_echo_ignore_all) {
779 struct icmp_bxm icmp_param;
780
781 icmp_param.data.icmph = *skb->h.icmph;
782 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
783 icmp_param.skb = skb;
784 icmp_param.offset = 0;
785 icmp_param.data_len = skb->len;
786 icmp_param.head_len = sizeof(struct icmphdr);
787 icmp_reply(&icmp_param, skb);
788 }
789 }
790
791 /*
792 * Handle ICMP Timestamp requests.
793 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
794 * SHOULD be in the kernel for minimum random latency.
795 * MUST be accurate to a few minutes.
796 * MUST be updated at least at 15Hz.
797 */
798 static void icmp_timestamp(struct sk_buff *skb)
799 {
800 struct timeval tv;
801 struct icmp_bxm icmp_param;
802 /*
803 * Too short.
804 */
805 if (skb->len < 4)
806 goto out_err;
807
808 /*
809 * Fill in the current time as ms since midnight UT:
810 */
811 do_gettimeofday(&tv);
812 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * 1000 +
813 tv.tv_usec / 1000);
814 icmp_param.data.times[2] = icmp_param.data.times[1];
815 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
816 BUG();
817 icmp_param.data.icmph = *skb->h.icmph;
818 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
819 icmp_param.data.icmph.code = 0;
820 icmp_param.skb = skb;
821 icmp_param.offset = 0;
822 icmp_param.data_len = 0;
823 icmp_param.head_len = sizeof(struct icmphdr) + 12;
824 icmp_reply(&icmp_param, skb);
825 out:
826 return;
827 out_err:
828 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
829 goto out;
830 }
831
832
833 /*
834 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
835 *
836 * RFC1122 (3.2.2.9). A host MUST only send replies to
837 * ADDRESS_MASK requests if it's been configured as an address mask
838 * agent. Receiving a request doesn't constitute implicit permission to
839 * act as one. Of course, implementing this correctly requires (SHOULD)
840 * a way to turn the functionality on and off. Another one for sysctl(),
841 * I guess. -- MS
842 *
843 * RFC1812 (4.3.3.9). A router MUST implement it.
844 * A router SHOULD have switch turning it on/off.
845 * This switch MUST be ON by default.
846 *
847 * Gratuitous replies, zero-source replies are not implemented,
848 * that complies with RFC. DO NOT implement them!!! All the idea
849 * of broadcast addrmask replies as specified in RFC950 is broken.
850 * The problem is that it is not uncommon to have several prefixes
851 * on one physical interface. Moreover, addrmask agent can even be
852 * not aware of existing another prefixes.
853 * If source is zero, addrmask agent cannot choose correct prefix.
854 * Gratuitous mask announcements suffer from the same problem.
855 * RFC1812 explains it, but still allows to use ADDRMASK,
856 * that is pretty silly. --ANK
857 *
858 * All these rules are so bizarre, that I removed kernel addrmask
859 * support at all. It is wrong, it is obsolete, nobody uses it in
860 * any case. --ANK
861 *
862 * Furthermore you can do it with a usermode address agent program
863 * anyway...
864 */
865
866 static void icmp_address(struct sk_buff *skb)
867 {
868 #if 0
869 if (net_ratelimit())
870 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
871 #endif
872 }
873
874 /*
875 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
876 * loudly if an inconsistency is found.
877 */
878
879 static void icmp_address_reply(struct sk_buff *skb)
880 {
881 struct rtable *rt = (struct rtable *)skb->dst;
882 struct net_device *dev = skb->dev;
883 struct in_device *in_dev;
884 struct in_ifaddr *ifa;
885
886 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
887 goto out;
888
889 in_dev = in_dev_get(dev);
890 if (!in_dev)
891 goto out;
892 rcu_read_lock();
893 if (in_dev->ifa_list &&
894 IN_DEV_LOG_MARTIANS(in_dev) &&
895 IN_DEV_FORWARD(in_dev)) {
896 u32 _mask, *mp;
897
898 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
899 BUG_ON(mp == NULL);
900 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
901 if (*mp == ifa->ifa_mask &&
902 inet_ifa_match(rt->rt_src, ifa))
903 break;
904 }
905 if (!ifa && net_ratelimit()) {
906 printk(KERN_INFO "Wrong address mask %u.%u.%u.%u from "
907 "%s/%u.%u.%u.%u\n",
908 NIPQUAD(*mp), dev->name, NIPQUAD(rt->rt_src));
909 }
910 }
911 rcu_read_unlock();
912 in_dev_put(in_dev);
913 out:;
914 }
915
916 static void icmp_discard(struct sk_buff *skb)
917 {
918 }
919
920 /*
921 * Deal with incoming ICMP packets.
922 */
923 int icmp_rcv(struct sk_buff *skb)
924 {
925 struct icmphdr *icmph;
926 struct rtable *rt = (struct rtable *)skb->dst;
927
928 ICMP_INC_STATS_BH(ICMP_MIB_INMSGS);
929
930 switch (skb->ip_summed) {
931 case CHECKSUM_HW:
932 if (!(u16)csum_fold(skb->csum))
933 break;
934 /* fall through */
935 case CHECKSUM_NONE:
936 skb->csum = 0;
937 if (__skb_checksum_complete(skb))
938 goto error;
939 }
940
941 if (!pskb_pull(skb, sizeof(struct icmphdr)))
942 goto error;
943
944 icmph = skb->h.icmph;
945
946 /*
947 * 18 is the highest 'known' ICMP type. Anything else is a mystery
948 *
949 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
950 * discarded.
951 */
952 if (icmph->type > NR_ICMP_TYPES)
953 goto error;
954
955
956 /*
957 * Parse the ICMP message
958 */
959
960 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
961 /*
962 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
963 * silently ignored (we let user decide with a sysctl).
964 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
965 * discarded if to broadcast/multicast.
966 */
967 if ((icmph->type == ICMP_ECHO ||
968 icmph->type == ICMP_TIMESTAMP) &&
969 sysctl_icmp_echo_ignore_broadcasts) {
970 goto error;
971 }
972 if (icmph->type != ICMP_ECHO &&
973 icmph->type != ICMP_TIMESTAMP &&
974 icmph->type != ICMP_ADDRESS &&
975 icmph->type != ICMP_ADDRESSREPLY) {
976 goto error;
977 }
978 }
979
980 ICMP_INC_STATS_BH(icmp_pointers[icmph->type].input_entry);
981 icmp_pointers[icmph->type].handler(skb);
982
983 drop:
984 kfree_skb(skb);
985 return 0;
986 error:
987 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
988 goto drop;
989 }
990
991 /*
992 * This table is the definition of how we handle ICMP.
993 */
994 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
995 [ICMP_ECHOREPLY] = {
996 .output_entry = ICMP_MIB_OUTECHOREPS,
997 .input_entry = ICMP_MIB_INECHOREPS,
998 .handler = icmp_discard,
999 },
1000 [1] = {
1001 .output_entry = ICMP_MIB_DUMMY,
1002 .input_entry = ICMP_MIB_INERRORS,
1003 .handler = icmp_discard,
1004 .error = 1,
1005 },
1006 [2] = {
1007 .output_entry = ICMP_MIB_DUMMY,
1008 .input_entry = ICMP_MIB_INERRORS,
1009 .handler = icmp_discard,
1010 .error = 1,
1011 },
1012 [ICMP_DEST_UNREACH] = {
1013 .output_entry = ICMP_MIB_OUTDESTUNREACHS,
1014 .input_entry = ICMP_MIB_INDESTUNREACHS,
1015 .handler = icmp_unreach,
1016 .error = 1,
1017 },
1018 [ICMP_SOURCE_QUENCH] = {
1019 .output_entry = ICMP_MIB_OUTSRCQUENCHS,
1020 .input_entry = ICMP_MIB_INSRCQUENCHS,
1021 .handler = icmp_unreach,
1022 .error = 1,
1023 },
1024 [ICMP_REDIRECT] = {
1025 .output_entry = ICMP_MIB_OUTREDIRECTS,
1026 .input_entry = ICMP_MIB_INREDIRECTS,
1027 .handler = icmp_redirect,
1028 .error = 1,
1029 },
1030 [6] = {
1031 .output_entry = ICMP_MIB_DUMMY,
1032 .input_entry = ICMP_MIB_INERRORS,
1033 .handler = icmp_discard,
1034 .error = 1,
1035 },
1036 [7] = {
1037 .output_entry = ICMP_MIB_DUMMY,
1038 .input_entry = ICMP_MIB_INERRORS,
1039 .handler = icmp_discard,
1040 .error = 1,
1041 },
1042 [ICMP_ECHO] = {
1043 .output_entry = ICMP_MIB_OUTECHOS,
1044 .input_entry = ICMP_MIB_INECHOS,
1045 .handler = icmp_echo,
1046 },
1047 [9] = {
1048 .output_entry = ICMP_MIB_DUMMY,
1049 .input_entry = ICMP_MIB_INERRORS,
1050 .handler = icmp_discard,
1051 .error = 1,
1052 },
1053 [10] = {
1054 .output_entry = ICMP_MIB_DUMMY,
1055 .input_entry = ICMP_MIB_INERRORS,
1056 .handler = icmp_discard,
1057 .error = 1,
1058 },
1059 [ICMP_TIME_EXCEEDED] = {
1060 .output_entry = ICMP_MIB_OUTTIMEEXCDS,
1061 .input_entry = ICMP_MIB_INTIMEEXCDS,
1062 .handler = icmp_unreach,
1063 .error = 1,
1064 },
1065 [ICMP_PARAMETERPROB] = {
1066 .output_entry = ICMP_MIB_OUTPARMPROBS,
1067 .input_entry = ICMP_MIB_INPARMPROBS,
1068 .handler = icmp_unreach,
1069 .error = 1,
1070 },
1071 [ICMP_TIMESTAMP] = {
1072 .output_entry = ICMP_MIB_OUTTIMESTAMPS,
1073 .input_entry = ICMP_MIB_INTIMESTAMPS,
1074 .handler = icmp_timestamp,
1075 },
1076 [ICMP_TIMESTAMPREPLY] = {
1077 .output_entry = ICMP_MIB_OUTTIMESTAMPREPS,
1078 .input_entry = ICMP_MIB_INTIMESTAMPREPS,
1079 .handler = icmp_discard,
1080 },
1081 [ICMP_INFO_REQUEST] = {
1082 .output_entry = ICMP_MIB_DUMMY,
1083 .input_entry = ICMP_MIB_DUMMY,
1084 .handler = icmp_discard,
1085 },
1086 [ICMP_INFO_REPLY] = {
1087 .output_entry = ICMP_MIB_DUMMY,
1088 .input_entry = ICMP_MIB_DUMMY,
1089 .handler = icmp_discard,
1090 },
1091 [ICMP_ADDRESS] = {
1092 .output_entry = ICMP_MIB_OUTADDRMASKS,
1093 .input_entry = ICMP_MIB_INADDRMASKS,
1094 .handler = icmp_address,
1095 },
1096 [ICMP_ADDRESSREPLY] = {
1097 .output_entry = ICMP_MIB_OUTADDRMASKREPS,
1098 .input_entry = ICMP_MIB_INADDRMASKREPS,
1099 .handler = icmp_address_reply,
1100 },
1101 };
1102
1103 void __init icmp_init(struct net_proto_family *ops)
1104 {
1105 struct inet_sock *inet;
1106 int i;
1107
1108 for_each_possible_cpu(i) {
1109 int err;
1110
1111 err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
1112 &per_cpu(__icmp_socket, i));
1113
1114 if (err < 0)
1115 panic("Failed to create the ICMP control socket.\n");
1116
1117 per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
1118
1119 /* Enough space for 2 64K ICMP packets, including
1120 * sk_buff struct overhead.
1121 */
1122 per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
1123 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1124
1125 inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
1126 inet->uc_ttl = -1;
1127 inet->pmtudisc = IP_PMTUDISC_DONT;
1128
1129 /* Unhash it so that IP input processing does not even
1130 * see it, we do not wish this socket to see incoming
1131 * packets.
1132 */
1133 per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
1134 }
1135 }
1136
1137 EXPORT_SYMBOL(icmp_err_convert);
1138 EXPORT_SYMBOL(icmp_send);
1139 EXPORT_SYMBOL(icmp_statistics);
1140 EXPORT_SYMBOL(xrlim_allow);
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