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ipv4: Pass flow keys down into datagram packet building engine.
[deliverable/linux.git] / net / ipv4 / icmp.c
1 /*
2 * NET3: Implementation of the ICMP protocol layer.
3 *
4 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * Some of the function names and the icmp unreach table for this
12 * module were derived from [icmp.c 1.0.11 06/02/93] by
13 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
14 * Other than that this module is a complete rewrite.
15 *
16 * Fixes:
17 * Clemens Fruhwirth : introduce global icmp rate limiting
18 * with icmp type masking ability instead
19 * of broken per type icmp timeouts.
20 * Mike Shaver : RFC1122 checks.
21 * Alan Cox : Multicast ping reply as self.
22 * Alan Cox : Fix atomicity lockup in ip_build_xmit
23 * call.
24 * Alan Cox : Added 216,128 byte paths to the MTU
25 * code.
26 * Martin Mares : RFC1812 checks.
27 * Martin Mares : Can be configured to follow redirects
28 * if acting as a router _without_ a
29 * routing protocol (RFC 1812).
30 * Martin Mares : Echo requests may be configured to
31 * be ignored (RFC 1812).
32 * Martin Mares : Limitation of ICMP error message
33 * transmit rate (RFC 1812).
34 * Martin Mares : TOS and Precedence set correctly
35 * (RFC 1812).
36 * Martin Mares : Now copying as much data from the
37 * original packet as we can without
38 * exceeding 576 bytes (RFC 1812).
39 * Willy Konynenberg : Transparent proxying support.
40 * Keith Owens : RFC1191 correction for 4.2BSD based
41 * path MTU bug.
42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
43 * valid (RFC 1812).
44 * Andi Kleen : Check all packet lengths properly
45 * and moved all kfree_skb() up to
46 * icmp_rcv.
47 * Andi Kleen : Move the rate limit bookkeeping
48 * into the dest entry and use a token
49 * bucket filter (thanks to ANK). Make
50 * the rates sysctl configurable.
51 * Yu Tianli : Fixed two ugly bugs in icmp_send
52 * - IP option length was accounted wrongly
53 * - ICMP header length was not accounted
54 * at all.
55 * Tristan Greaves : Added sysctl option to ignore bogus
56 * broadcast responses from broken routers.
57 *
58 * To Fix:
59 *
60 * - Should use skb_pull() instead of all the manual checking.
61 * This would also greatly simply some upper layer error handlers. --AK
62 *
63 */
64
65 #include <linux/module.h>
66 #include <linux/types.h>
67 #include <linux/jiffies.h>
68 #include <linux/kernel.h>
69 #include <linux/fcntl.h>
70 #include <linux/socket.h>
71 #include <linux/in.h>
72 #include <linux/inet.h>
73 #include <linux/inetdevice.h>
74 #include <linux/netdevice.h>
75 #include <linux/string.h>
76 #include <linux/netfilter_ipv4.h>
77 #include <linux/slab.h>
78 #include <net/snmp.h>
79 #include <net/ip.h>
80 #include <net/route.h>
81 #include <net/protocol.h>
82 #include <net/icmp.h>
83 #include <net/tcp.h>
84 #include <net/udp.h>
85 #include <net/raw.h>
86 #include <linux/skbuff.h>
87 #include <net/sock.h>
88 #include <linux/errno.h>
89 #include <linux/timer.h>
90 #include <linux/init.h>
91 #include <asm/system.h>
92 #include <asm/uaccess.h>
93 #include <net/checksum.h>
94 #include <net/xfrm.h>
95 #include <net/inet_common.h>
96
97 /*
98 * Build xmit assembly blocks
99 */
100
101 struct icmp_bxm {
102 struct sk_buff *skb;
103 int offset;
104 int data_len;
105
106 struct {
107 struct icmphdr icmph;
108 __be32 times[3];
109 } data;
110 int head_len;
111 struct ip_options_data replyopts;
112 };
113
114 /* An array of errno for error messages from dest unreach. */
115 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
116
117 const struct icmp_err icmp_err_convert[] = {
118 {
119 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
120 .fatal = 0,
121 },
122 {
123 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
124 .fatal = 0,
125 },
126 {
127 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
128 .fatal = 1,
129 },
130 {
131 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
132 .fatal = 1,
133 },
134 {
135 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
136 .fatal = 0,
137 },
138 {
139 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
140 .fatal = 0,
141 },
142 {
143 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
144 .fatal = 1,
145 },
146 {
147 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
148 .fatal = 1,
149 },
150 {
151 .errno = ENONET, /* ICMP_HOST_ISOLATED */
152 .fatal = 1,
153 },
154 {
155 .errno = ENETUNREACH, /* ICMP_NET_ANO */
156 .fatal = 1,
157 },
158 {
159 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
160 .fatal = 1,
161 },
162 {
163 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
164 .fatal = 0,
165 },
166 {
167 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
168 .fatal = 0,
169 },
170 {
171 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
172 .fatal = 1,
173 },
174 {
175 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
176 .fatal = 1,
177 },
178 {
179 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
180 .fatal = 1,
181 },
182 };
183 EXPORT_SYMBOL(icmp_err_convert);
184
185 /*
186 * ICMP control array. This specifies what to do with each ICMP.
187 */
188
189 struct icmp_control {
190 void (*handler)(struct sk_buff *skb);
191 short error; /* This ICMP is classed as an error message */
192 };
193
194 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
195
196 /*
197 * The ICMP socket(s). This is the most convenient way to flow control
198 * our ICMP output as well as maintain a clean interface throughout
199 * all layers. All Socketless IP sends will soon be gone.
200 *
201 * On SMP we have one ICMP socket per-cpu.
202 */
203 static struct sock *icmp_sk(struct net *net)
204 {
205 return net->ipv4.icmp_sk[smp_processor_id()];
206 }
207
208 static inline struct sock *icmp_xmit_lock(struct net *net)
209 {
210 struct sock *sk;
211
212 local_bh_disable();
213
214 sk = icmp_sk(net);
215
216 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
217 /* This can happen if the output path signals a
218 * dst_link_failure() for an outgoing ICMP packet.
219 */
220 local_bh_enable();
221 return NULL;
222 }
223 return sk;
224 }
225
226 static inline void icmp_xmit_unlock(struct sock *sk)
227 {
228 spin_unlock_bh(&sk->sk_lock.slock);
229 }
230
231 /*
232 * Send an ICMP frame.
233 */
234
235 static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
236 int type, int code)
237 {
238 struct dst_entry *dst = &rt->dst;
239 bool rc = true;
240
241 if (type > NR_ICMP_TYPES)
242 goto out;
243
244 /* Don't limit PMTU discovery. */
245 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
246 goto out;
247
248 /* No rate limit on loopback */
249 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
250 goto out;
251
252 /* Limit if icmp type is enabled in ratemask. */
253 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
254 if (!rt->peer)
255 rt_bind_peer(rt, 1);
256 rc = inet_peer_xrlim_allow(rt->peer,
257 net->ipv4.sysctl_icmp_ratelimit);
258 }
259 out:
260 return rc;
261 }
262
263 /*
264 * Maintain the counters used in the SNMP statistics for outgoing ICMP
265 */
266 void icmp_out_count(struct net *net, unsigned char type)
267 {
268 ICMPMSGOUT_INC_STATS(net, type);
269 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
270 }
271
272 /*
273 * Checksum each fragment, and on the first include the headers and final
274 * checksum.
275 */
276 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
277 struct sk_buff *skb)
278 {
279 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
280 __wsum csum;
281
282 csum = skb_copy_and_csum_bits(icmp_param->skb,
283 icmp_param->offset + offset,
284 to, len, 0);
285
286 skb->csum = csum_block_add(skb->csum, csum, odd);
287 if (icmp_pointers[icmp_param->data.icmph.type].error)
288 nf_ct_attach(skb, icmp_param->skb);
289 return 0;
290 }
291
292 static void icmp_push_reply(struct icmp_bxm *icmp_param,
293 struct flowi4 *fl4,
294 struct ipcm_cookie *ipc, struct rtable **rt)
295 {
296 struct sock *sk;
297 struct sk_buff *skb;
298
299 sk = icmp_sk(dev_net((*rt)->dst.dev));
300 if (ip_append_data(sk, icmp_glue_bits, icmp_param,
301 icmp_param->data_len+icmp_param->head_len,
302 icmp_param->head_len,
303 ipc, rt, MSG_DONTWAIT) < 0) {
304 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
305 ip_flush_pending_frames(sk);
306 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
307 struct icmphdr *icmph = icmp_hdr(skb);
308 __wsum csum = 0;
309 struct sk_buff *skb1;
310
311 skb_queue_walk(&sk->sk_write_queue, skb1) {
312 csum = csum_add(csum, skb1->csum);
313 }
314 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
315 (char *)icmph,
316 icmp_param->head_len, csum);
317 icmph->checksum = csum_fold(csum);
318 skb->ip_summed = CHECKSUM_NONE;
319 ip_push_pending_frames(sk, fl4);
320 }
321 }
322
323 /*
324 * Driving logic for building and sending ICMP messages.
325 */
326
327 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
328 {
329 struct ipcm_cookie ipc;
330 struct rtable *rt = skb_rtable(skb);
331 struct net *net = dev_net(rt->dst.dev);
332 struct flowi4 fl4;
333 struct sock *sk;
334 struct inet_sock *inet;
335 __be32 daddr;
336
337 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
338 return;
339
340 sk = icmp_xmit_lock(net);
341 if (sk == NULL)
342 return;
343 inet = inet_sk(sk);
344
345 icmp_param->data.icmph.checksum = 0;
346
347 inet->tos = ip_hdr(skb)->tos;
348 daddr = ipc.addr = rt->rt_src;
349 ipc.opt = NULL;
350 ipc.tx_flags = 0;
351 if (icmp_param->replyopts.opt.opt.optlen) {
352 ipc.opt = &icmp_param->replyopts.opt;
353 if (ipc.opt->opt.srr)
354 daddr = icmp_param->replyopts.opt.opt.faddr;
355 }
356 memset(&fl4, 0, sizeof(fl4));
357 fl4.daddr = daddr;
358 fl4.saddr = rt->rt_spec_dst;
359 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
360 fl4.flowi4_proto = IPPROTO_ICMP;
361 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
362 rt = ip_route_output_key(net, &fl4);
363 if (IS_ERR(rt))
364 goto out_unlock;
365 if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type,
366 icmp_param->data.icmph.code))
367 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
368 ip_rt_put(rt);
369 out_unlock:
370 icmp_xmit_unlock(sk);
371 }
372
373 static struct rtable *icmp_route_lookup(struct net *net,
374 struct flowi4 *fl4,
375 struct sk_buff *skb_in,
376 const struct iphdr *iph,
377 __be32 saddr, u8 tos,
378 int type, int code,
379 struct icmp_bxm *param)
380 {
381 struct rtable *rt, *rt2;
382 int err;
383
384 memset(fl4, 0, sizeof(*fl4));
385 fl4->daddr = (param->replyopts.opt.opt.srr ?
386 param->replyopts.opt.opt.faddr : iph->saddr);
387 fl4->saddr = saddr;
388 fl4->flowi4_tos = RT_TOS(tos);
389 fl4->flowi4_proto = IPPROTO_ICMP;
390 fl4->fl4_icmp_type = type;
391 fl4->fl4_icmp_code = code;
392 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
393 rt = __ip_route_output_key(net, fl4);
394 if (IS_ERR(rt))
395 return rt;
396
397 /* No need to clone since we're just using its address. */
398 rt2 = rt;
399
400 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
401 flowi4_to_flowi(fl4), NULL, 0);
402 if (!IS_ERR(rt)) {
403 if (rt != rt2)
404 return rt;
405 } else if (PTR_ERR(rt) == -EPERM) {
406 rt = NULL;
407 } else
408 return rt;
409
410 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(fl4), AF_INET);
411 if (err)
412 goto relookup_failed;
413
414 if (inet_addr_type(net, fl4->saddr) == RTN_LOCAL) {
415 rt2 = __ip_route_output_key(net, fl4);
416 if (IS_ERR(rt2))
417 err = PTR_ERR(rt2);
418 } else {
419 struct flowi4 fl4_2 = {};
420 unsigned long orefdst;
421
422 fl4_2.daddr = fl4->saddr;
423 rt2 = ip_route_output_key(net, &fl4_2);
424 if (IS_ERR(rt2)) {
425 err = PTR_ERR(rt2);
426 goto relookup_failed;
427 }
428 /* Ugh! */
429 orefdst = skb_in->_skb_refdst; /* save old refdst */
430 err = ip_route_input(skb_in, fl4->daddr, fl4->saddr,
431 RT_TOS(tos), rt2->dst.dev);
432
433 dst_release(&rt2->dst);
434 rt2 = skb_rtable(skb_in);
435 skb_in->_skb_refdst = orefdst; /* restore old refdst */
436 }
437
438 if (err)
439 goto relookup_failed;
440
441 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
442 flowi4_to_flowi(fl4), NULL,
443 XFRM_LOOKUP_ICMP);
444 if (!IS_ERR(rt2)) {
445 dst_release(&rt->dst);
446 rt = rt2;
447 } else if (PTR_ERR(rt2) == -EPERM) {
448 if (rt)
449 dst_release(&rt->dst);
450 return rt2;
451 } else {
452 err = PTR_ERR(rt2);
453 goto relookup_failed;
454 }
455 return rt;
456
457 relookup_failed:
458 if (rt)
459 return rt;
460 return ERR_PTR(err);
461 }
462
463 /*
464 * Send an ICMP message in response to a situation
465 *
466 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
467 * MAY send more (we do).
468 * MUST NOT change this header information.
469 * MUST NOT reply to a multicast/broadcast IP address.
470 * MUST NOT reply to a multicast/broadcast MAC address.
471 * MUST reply to only the first fragment.
472 */
473
474 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
475 {
476 struct iphdr *iph;
477 int room;
478 struct icmp_bxm icmp_param;
479 struct rtable *rt = skb_rtable(skb_in);
480 struct ipcm_cookie ipc;
481 struct flowi4 fl4;
482 __be32 saddr;
483 u8 tos;
484 struct net *net;
485 struct sock *sk;
486
487 if (!rt)
488 goto out;
489 net = dev_net(rt->dst.dev);
490
491 /*
492 * Find the original header. It is expected to be valid, of course.
493 * Check this, icmp_send is called from the most obscure devices
494 * sometimes.
495 */
496 iph = ip_hdr(skb_in);
497
498 if ((u8 *)iph < skb_in->head ||
499 (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
500 goto out;
501
502 /*
503 * No replies to physical multicast/broadcast
504 */
505 if (skb_in->pkt_type != PACKET_HOST)
506 goto out;
507
508 /*
509 * Now check at the protocol level
510 */
511 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
512 goto out;
513
514 /*
515 * Only reply to fragment 0. We byte re-order the constant
516 * mask for efficiency.
517 */
518 if (iph->frag_off & htons(IP_OFFSET))
519 goto out;
520
521 /*
522 * If we send an ICMP error to an ICMP error a mess would result..
523 */
524 if (icmp_pointers[type].error) {
525 /*
526 * We are an error, check if we are replying to an
527 * ICMP error
528 */
529 if (iph->protocol == IPPROTO_ICMP) {
530 u8 _inner_type, *itp;
531
532 itp = skb_header_pointer(skb_in,
533 skb_network_header(skb_in) +
534 (iph->ihl << 2) +
535 offsetof(struct icmphdr,
536 type) -
537 skb_in->data,
538 sizeof(_inner_type),
539 &_inner_type);
540 if (itp == NULL)
541 goto out;
542
543 /*
544 * Assume any unknown ICMP type is an error. This
545 * isn't specified by the RFC, but think about it..
546 */
547 if (*itp > NR_ICMP_TYPES ||
548 icmp_pointers[*itp].error)
549 goto out;
550 }
551 }
552
553 sk = icmp_xmit_lock(net);
554 if (sk == NULL)
555 return;
556
557 /*
558 * Construct source address and options.
559 */
560
561 saddr = iph->daddr;
562 if (!(rt->rt_flags & RTCF_LOCAL)) {
563 struct net_device *dev = NULL;
564
565 rcu_read_lock();
566 if (rt_is_input_route(rt) &&
567 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
568 dev = dev_get_by_index_rcu(net, rt->rt_iif);
569
570 if (dev)
571 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
572 else
573 saddr = 0;
574 rcu_read_unlock();
575 }
576
577 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
578 IPTOS_PREC_INTERNETCONTROL) :
579 iph->tos;
580
581 if (ip_options_echo(&icmp_param.replyopts.opt.opt, skb_in))
582 goto out_unlock;
583
584
585 /*
586 * Prepare data for ICMP header.
587 */
588
589 icmp_param.data.icmph.type = type;
590 icmp_param.data.icmph.code = code;
591 icmp_param.data.icmph.un.gateway = info;
592 icmp_param.data.icmph.checksum = 0;
593 icmp_param.skb = skb_in;
594 icmp_param.offset = skb_network_offset(skb_in);
595 inet_sk(sk)->tos = tos;
596 ipc.addr = iph->saddr;
597 ipc.opt = &icmp_param.replyopts.opt;
598 ipc.tx_flags = 0;
599
600 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
601 type, code, &icmp_param);
602 if (IS_ERR(rt))
603 goto out_unlock;
604
605 if (!icmpv4_xrlim_allow(net, rt, type, code))
606 goto ende;
607
608 /* RFC says return as much as we can without exceeding 576 bytes. */
609
610 room = dst_mtu(&rt->dst);
611 if (room > 576)
612 room = 576;
613 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
614 room -= sizeof(struct icmphdr);
615
616 icmp_param.data_len = skb_in->len - icmp_param.offset;
617 if (icmp_param.data_len > room)
618 icmp_param.data_len = room;
619 icmp_param.head_len = sizeof(struct icmphdr);
620
621 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
622 ende:
623 ip_rt_put(rt);
624 out_unlock:
625 icmp_xmit_unlock(sk);
626 out:;
627 }
628 EXPORT_SYMBOL(icmp_send);
629
630
631 /*
632 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH.
633 */
634
635 static void icmp_unreach(struct sk_buff *skb)
636 {
637 const struct iphdr *iph;
638 struct icmphdr *icmph;
639 int hash, protocol;
640 const struct net_protocol *ipprot;
641 u32 info = 0;
642 struct net *net;
643
644 net = dev_net(skb_dst(skb)->dev);
645
646 /*
647 * Incomplete header ?
648 * Only checks for the IP header, there should be an
649 * additional check for longer headers in upper levels.
650 */
651
652 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
653 goto out_err;
654
655 icmph = icmp_hdr(skb);
656 iph = (const struct iphdr *)skb->data;
657
658 if (iph->ihl < 5) /* Mangled header, drop. */
659 goto out_err;
660
661 if (icmph->type == ICMP_DEST_UNREACH) {
662 switch (icmph->code & 15) {
663 case ICMP_NET_UNREACH:
664 case ICMP_HOST_UNREACH:
665 case ICMP_PROT_UNREACH:
666 case ICMP_PORT_UNREACH:
667 break;
668 case ICMP_FRAG_NEEDED:
669 if (ipv4_config.no_pmtu_disc) {
670 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n",
671 &iph->daddr);
672 } else {
673 info = ip_rt_frag_needed(net, iph,
674 ntohs(icmph->un.frag.mtu),
675 skb->dev);
676 if (!info)
677 goto out;
678 }
679 break;
680 case ICMP_SR_FAILED:
681 LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n",
682 &iph->daddr);
683 break;
684 default:
685 break;
686 }
687 if (icmph->code > NR_ICMP_UNREACH)
688 goto out;
689 } else if (icmph->type == ICMP_PARAMETERPROB)
690 info = ntohl(icmph->un.gateway) >> 24;
691
692 /*
693 * Throw it at our lower layers
694 *
695 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
696 * header.
697 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
698 * transport layer.
699 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
700 * transport layer.
701 */
702
703 /*
704 * Check the other end isn't violating RFC 1122. Some routers send
705 * bogus responses to broadcast frames. If you see this message
706 * first check your netmask matches at both ends, if it does then
707 * get the other vendor to fix their kit.
708 */
709
710 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
711 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
712 if (net_ratelimit())
713 printk(KERN_WARNING "%pI4 sent an invalid ICMP "
714 "type %u, code %u "
715 "error to a broadcast: %pI4 on %s\n",
716 &ip_hdr(skb)->saddr,
717 icmph->type, icmph->code,
718 &iph->daddr,
719 skb->dev->name);
720 goto out;
721 }
722
723 /* Checkin full IP header plus 8 bytes of protocol to
724 * avoid additional coding at protocol handlers.
725 */
726 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
727 goto out;
728
729 iph = (const struct iphdr *)skb->data;
730 protocol = iph->protocol;
731
732 /*
733 * Deliver ICMP message to raw sockets. Pretty useless feature?
734 */
735 raw_icmp_error(skb, protocol, info);
736
737 hash = protocol & (MAX_INET_PROTOS - 1);
738 rcu_read_lock();
739 ipprot = rcu_dereference(inet_protos[hash]);
740 if (ipprot && ipprot->err_handler)
741 ipprot->err_handler(skb, info);
742 rcu_read_unlock();
743
744 out:
745 return;
746 out_err:
747 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
748 goto out;
749 }
750
751
752 /*
753 * Handle ICMP_REDIRECT.
754 */
755
756 static void icmp_redirect(struct sk_buff *skb)
757 {
758 const struct iphdr *iph;
759
760 if (skb->len < sizeof(struct iphdr))
761 goto out_err;
762
763 /*
764 * Get the copied header of the packet that caused the redirect
765 */
766 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
767 goto out;
768
769 iph = (const struct iphdr *)skb->data;
770
771 switch (icmp_hdr(skb)->code & 7) {
772 case ICMP_REDIR_NET:
773 case ICMP_REDIR_NETTOS:
774 /*
775 * As per RFC recommendations now handle it as a host redirect.
776 */
777 case ICMP_REDIR_HOST:
778 case ICMP_REDIR_HOSTTOS:
779 ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr,
780 icmp_hdr(skb)->un.gateway,
781 iph->saddr, skb->dev);
782 break;
783 }
784 out:
785 return;
786 out_err:
787 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
788 goto out;
789 }
790
791 /*
792 * Handle ICMP_ECHO ("ping") requests.
793 *
794 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
795 * requests.
796 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
797 * included in the reply.
798 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
799 * echo requests, MUST have default=NOT.
800 * See also WRT handling of options once they are done and working.
801 */
802
803 static void icmp_echo(struct sk_buff *skb)
804 {
805 struct net *net;
806
807 net = dev_net(skb_dst(skb)->dev);
808 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
809 struct icmp_bxm icmp_param;
810
811 icmp_param.data.icmph = *icmp_hdr(skb);
812 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
813 icmp_param.skb = skb;
814 icmp_param.offset = 0;
815 icmp_param.data_len = skb->len;
816 icmp_param.head_len = sizeof(struct icmphdr);
817 icmp_reply(&icmp_param, skb);
818 }
819 }
820
821 /*
822 * Handle ICMP Timestamp requests.
823 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
824 * SHOULD be in the kernel for minimum random latency.
825 * MUST be accurate to a few minutes.
826 * MUST be updated at least at 15Hz.
827 */
828 static void icmp_timestamp(struct sk_buff *skb)
829 {
830 struct timespec tv;
831 struct icmp_bxm icmp_param;
832 /*
833 * Too short.
834 */
835 if (skb->len < 4)
836 goto out_err;
837
838 /*
839 * Fill in the current time as ms since midnight UT:
840 */
841 getnstimeofday(&tv);
842 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
843 tv.tv_nsec / NSEC_PER_MSEC);
844 icmp_param.data.times[2] = icmp_param.data.times[1];
845 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
846 BUG();
847 icmp_param.data.icmph = *icmp_hdr(skb);
848 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
849 icmp_param.data.icmph.code = 0;
850 icmp_param.skb = skb;
851 icmp_param.offset = 0;
852 icmp_param.data_len = 0;
853 icmp_param.head_len = sizeof(struct icmphdr) + 12;
854 icmp_reply(&icmp_param, skb);
855 out:
856 return;
857 out_err:
858 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
859 goto out;
860 }
861
862
863 /*
864 * Handle ICMP_ADDRESS_MASK requests. (RFC950)
865 *
866 * RFC1122 (3.2.2.9). A host MUST only send replies to
867 * ADDRESS_MASK requests if it's been configured as an address mask
868 * agent. Receiving a request doesn't constitute implicit permission to
869 * act as one. Of course, implementing this correctly requires (SHOULD)
870 * a way to turn the functionality on and off. Another one for sysctl(),
871 * I guess. -- MS
872 *
873 * RFC1812 (4.3.3.9). A router MUST implement it.
874 * A router SHOULD have switch turning it on/off.
875 * This switch MUST be ON by default.
876 *
877 * Gratuitous replies, zero-source replies are not implemented,
878 * that complies with RFC. DO NOT implement them!!! All the idea
879 * of broadcast addrmask replies as specified in RFC950 is broken.
880 * The problem is that it is not uncommon to have several prefixes
881 * on one physical interface. Moreover, addrmask agent can even be
882 * not aware of existing another prefixes.
883 * If source is zero, addrmask agent cannot choose correct prefix.
884 * Gratuitous mask announcements suffer from the same problem.
885 * RFC1812 explains it, but still allows to use ADDRMASK,
886 * that is pretty silly. --ANK
887 *
888 * All these rules are so bizarre, that I removed kernel addrmask
889 * support at all. It is wrong, it is obsolete, nobody uses it in
890 * any case. --ANK
891 *
892 * Furthermore you can do it with a usermode address agent program
893 * anyway...
894 */
895
896 static void icmp_address(struct sk_buff *skb)
897 {
898 #if 0
899 if (net_ratelimit())
900 printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n");
901 #endif
902 }
903
904 /*
905 * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain
906 * loudly if an inconsistency is found.
907 * called with rcu_read_lock()
908 */
909
910 static void icmp_address_reply(struct sk_buff *skb)
911 {
912 struct rtable *rt = skb_rtable(skb);
913 struct net_device *dev = skb->dev;
914 struct in_device *in_dev;
915 struct in_ifaddr *ifa;
916
917 if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC))
918 return;
919
920 in_dev = __in_dev_get_rcu(dev);
921 if (!in_dev)
922 return;
923
924 if (in_dev->ifa_list &&
925 IN_DEV_LOG_MARTIANS(in_dev) &&
926 IN_DEV_FORWARD(in_dev)) {
927 __be32 _mask, *mp;
928
929 mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask);
930 BUG_ON(mp == NULL);
931 for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
932 if (*mp == ifa->ifa_mask &&
933 inet_ifa_match(rt->rt_src, ifa))
934 break;
935 }
936 if (!ifa && net_ratelimit()) {
937 printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n",
938 mp, dev->name, &rt->rt_src);
939 }
940 }
941 }
942
943 static void icmp_discard(struct sk_buff *skb)
944 {
945 }
946
947 /*
948 * Deal with incoming ICMP packets.
949 */
950 int icmp_rcv(struct sk_buff *skb)
951 {
952 struct icmphdr *icmph;
953 struct rtable *rt = skb_rtable(skb);
954 struct net *net = dev_net(rt->dst.dev);
955
956 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
957 struct sec_path *sp = skb_sec_path(skb);
958 int nh;
959
960 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
961 XFRM_STATE_ICMP))
962 goto drop;
963
964 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
965 goto drop;
966
967 nh = skb_network_offset(skb);
968 skb_set_network_header(skb, sizeof(*icmph));
969
970 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
971 goto drop;
972
973 skb_set_network_header(skb, nh);
974 }
975
976 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
977
978 switch (skb->ip_summed) {
979 case CHECKSUM_COMPLETE:
980 if (!csum_fold(skb->csum))
981 break;
982 /* fall through */
983 case CHECKSUM_NONE:
984 skb->csum = 0;
985 if (__skb_checksum_complete(skb))
986 goto error;
987 }
988
989 if (!pskb_pull(skb, sizeof(*icmph)))
990 goto error;
991
992 icmph = icmp_hdr(skb);
993
994 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
995 /*
996 * 18 is the highest 'known' ICMP type. Anything else is a mystery
997 *
998 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
999 * discarded.
1000 */
1001 if (icmph->type > NR_ICMP_TYPES)
1002 goto error;
1003
1004
1005 /*
1006 * Parse the ICMP message
1007 */
1008
1009 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1010 /*
1011 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1012 * silently ignored (we let user decide with a sysctl).
1013 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1014 * discarded if to broadcast/multicast.
1015 */
1016 if ((icmph->type == ICMP_ECHO ||
1017 icmph->type == ICMP_TIMESTAMP) &&
1018 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1019 goto error;
1020 }
1021 if (icmph->type != ICMP_ECHO &&
1022 icmph->type != ICMP_TIMESTAMP &&
1023 icmph->type != ICMP_ADDRESS &&
1024 icmph->type != ICMP_ADDRESSREPLY) {
1025 goto error;
1026 }
1027 }
1028
1029 icmp_pointers[icmph->type].handler(skb);
1030
1031 drop:
1032 kfree_skb(skb);
1033 return 0;
1034 error:
1035 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
1036 goto drop;
1037 }
1038
1039 /*
1040 * This table is the definition of how we handle ICMP.
1041 */
1042 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1043 [ICMP_ECHOREPLY] = {
1044 .handler = icmp_discard,
1045 },
1046 [1] = {
1047 .handler = icmp_discard,
1048 .error = 1,
1049 },
1050 [2] = {
1051 .handler = icmp_discard,
1052 .error = 1,
1053 },
1054 [ICMP_DEST_UNREACH] = {
1055 .handler = icmp_unreach,
1056 .error = 1,
1057 },
1058 [ICMP_SOURCE_QUENCH] = {
1059 .handler = icmp_unreach,
1060 .error = 1,
1061 },
1062 [ICMP_REDIRECT] = {
1063 .handler = icmp_redirect,
1064 .error = 1,
1065 },
1066 [6] = {
1067 .handler = icmp_discard,
1068 .error = 1,
1069 },
1070 [7] = {
1071 .handler = icmp_discard,
1072 .error = 1,
1073 },
1074 [ICMP_ECHO] = {
1075 .handler = icmp_echo,
1076 },
1077 [9] = {
1078 .handler = icmp_discard,
1079 .error = 1,
1080 },
1081 [10] = {
1082 .handler = icmp_discard,
1083 .error = 1,
1084 },
1085 [ICMP_TIME_EXCEEDED] = {
1086 .handler = icmp_unreach,
1087 .error = 1,
1088 },
1089 [ICMP_PARAMETERPROB] = {
1090 .handler = icmp_unreach,
1091 .error = 1,
1092 },
1093 [ICMP_TIMESTAMP] = {
1094 .handler = icmp_timestamp,
1095 },
1096 [ICMP_TIMESTAMPREPLY] = {
1097 .handler = icmp_discard,
1098 },
1099 [ICMP_INFO_REQUEST] = {
1100 .handler = icmp_discard,
1101 },
1102 [ICMP_INFO_REPLY] = {
1103 .handler = icmp_discard,
1104 },
1105 [ICMP_ADDRESS] = {
1106 .handler = icmp_address,
1107 },
1108 [ICMP_ADDRESSREPLY] = {
1109 .handler = icmp_address_reply,
1110 },
1111 };
1112
1113 static void __net_exit icmp_sk_exit(struct net *net)
1114 {
1115 int i;
1116
1117 for_each_possible_cpu(i)
1118 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1119 kfree(net->ipv4.icmp_sk);
1120 net->ipv4.icmp_sk = NULL;
1121 }
1122
1123 static int __net_init icmp_sk_init(struct net *net)
1124 {
1125 int i, err;
1126
1127 net->ipv4.icmp_sk =
1128 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1129 if (net->ipv4.icmp_sk == NULL)
1130 return -ENOMEM;
1131
1132 for_each_possible_cpu(i) {
1133 struct sock *sk;
1134
1135 err = inet_ctl_sock_create(&sk, PF_INET,
1136 SOCK_RAW, IPPROTO_ICMP, net);
1137 if (err < 0)
1138 goto fail;
1139
1140 net->ipv4.icmp_sk[i] = sk;
1141
1142 /* Enough space for 2 64K ICMP packets, including
1143 * sk_buff struct overhead.
1144 */
1145 sk->sk_sndbuf =
1146 (2 * ((64 * 1024) + sizeof(struct sk_buff)));
1147
1148 /*
1149 * Speedup sock_wfree()
1150 */
1151 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1152 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1153 }
1154
1155 /* Control parameters for ECHO replies. */
1156 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1157 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1158
1159 /* Control parameter - ignore bogus broadcast responses? */
1160 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1161
1162 /*
1163 * Configurable global rate limit.
1164 *
1165 * ratelimit defines tokens/packet consumed for dst->rate_token
1166 * bucket ratemask defines which icmp types are ratelimited by
1167 * setting it's bit position.
1168 *
1169 * default:
1170 * dest unreachable (3), source quench (4),
1171 * time exceeded (11), parameter problem (12)
1172 */
1173
1174 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1175 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1176 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1177
1178 return 0;
1179
1180 fail:
1181 for_each_possible_cpu(i)
1182 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1183 kfree(net->ipv4.icmp_sk);
1184 return err;
1185 }
1186
1187 static struct pernet_operations __net_initdata icmp_sk_ops = {
1188 .init = icmp_sk_init,
1189 .exit = icmp_sk_exit,
1190 };
1191
1192 int __init icmp_init(void)
1193 {
1194 return register_pernet_subsys(&icmp_sk_ops);
1195 }
Linux kernel - Deliverables
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