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Merge tag 'gpio-v3.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw...
[linux-2.6.git] / net / ipv4 / icmp.c
blob5c0e8bc6e5ba275d2469336533b5848de94ae6c1
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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 <linux/slab.h>
80 #include <net/snmp.h>
81 #include <net/ip.h>
82 #include <net/route.h>
83 #include <net/protocol.h>
84 #include <net/icmp.h>
85 #include <net/tcp.h>
86 #include <net/udp.h>
87 #include <net/raw.h>
88 #include <net/ping.h>
89 #include <linux/skbuff.h>
90 #include <net/sock.h>
91 #include <linux/errno.h>
92 #include <linux/timer.h>
93 #include <linux/init.h>
94 #include <asm/uaccess.h>
95 #include <net/checksum.h>
96 #include <net/xfrm.h>
97 #include <net/inet_common.h>
98 #include <net/ip_fib.h>
99
100 /*
101 * Build xmit assembly blocks
102 */
103
104 struct icmp_bxm {
105 struct sk_buff *skb;
106 int offset;
107 int data_len;
108
109 struct {
110 struct icmphdr icmph;
111 __be32 times[3];
112 } data;
113 int head_len;
114 struct ip_options_data replyopts;
115 };
116
117 /* An array of errno for error messages from dest unreach. */
118 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
119
120 const struct icmp_err icmp_err_convert[] = {
121 {
122 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
123 .fatal = 0,
124 },
125 {
126 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
127 .fatal = 0,
128 },
129 {
130 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
131 .fatal = 1,
132 },
133 {
134 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
135 .fatal = 1,
136 },
137 {
138 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
139 .fatal = 0,
140 },
141 {
142 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
143 .fatal = 0,
144 },
145 {
146 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
147 .fatal = 1,
148 },
149 {
150 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
151 .fatal = 1,
152 },
153 {
154 .errno = ENONET, /* ICMP_HOST_ISOLATED */
155 .fatal = 1,
156 },
157 {
158 .errno = ENETUNREACH, /* ICMP_NET_ANO */
159 .fatal = 1,
160 },
161 {
162 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
163 .fatal = 1,
164 },
165 {
166 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
167 .fatal = 0,
168 },
169 {
170 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
171 .fatal = 0,
172 },
173 {
174 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
175 .fatal = 1,
176 },
177 {
178 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
179 .fatal = 1,
180 },
181 {
182 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
183 .fatal = 1,
184 },
185 };
186 EXPORT_SYMBOL(icmp_err_convert);
187
188 /*
189 * ICMP control array. This specifies what to do with each ICMP.
190 */
191
192 struct icmp_control {
193 void (*handler)(struct sk_buff *skb);
194 short error; /* This ICMP is classed as an error message */
195 };
196
197 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
198
199 /*
200 * The ICMP socket(s). This is the most convenient way to flow control
201 * our ICMP output as well as maintain a clean interface throughout
202 * all layers. All Socketless IP sends will soon be gone.
203 *
204 * On SMP we have one ICMP socket per-cpu.
205 */
206 static struct sock *icmp_sk(struct net *net)
207 {
208 return net->ipv4.icmp_sk[smp_processor_id()];
209 }
210
211 static inline struct sock *icmp_xmit_lock(struct net *net)
212 {
213 struct sock *sk;
214
215 local_bh_disable();
216
217 sk = icmp_sk(net);
218
219 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
220 /* This can happen if the output path signals a
221 * dst_link_failure() for an outgoing ICMP packet.
222 */
223 local_bh_enable();
224 return NULL;
225 }
226 return sk;
227 }
228
229 static inline void icmp_xmit_unlock(struct sock *sk)
230 {
231 spin_unlock_bh(&sk->sk_lock.slock);
232 }
233
234 /*
235 * Send an ICMP frame.
236 */
237
238 static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
239 struct flowi4 *fl4, int type, int code)
240 {
241 struct dst_entry *dst = &rt->dst;
242 bool rc = true;
243
244 if (type > NR_ICMP_TYPES)
245 goto out;
246
247 /* Don't limit PMTU discovery. */
248 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
249 goto out;
250
251 /* No rate limit on loopback */
252 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
253 goto out;
254
255 /* Limit if icmp type is enabled in ratemask. */
256 if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) {
257 struct inet_peer *peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, 1);
258 rc = inet_peer_xrlim_allow(peer,
259 net->ipv4.sysctl_icmp_ratelimit);
260 if (peer)
261 inet_putpeer(peer);
262 }
263 out:
264 return rc;
265 }
266
267 /*
268 * Maintain the counters used in the SNMP statistics for outgoing ICMP
269 */
270 void icmp_out_count(struct net *net, unsigned char type)
271 {
272 ICMPMSGOUT_INC_STATS(net, type);
273 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
274 }
275
276 /*
277 * Checksum each fragment, and on the first include the headers and final
278 * checksum.
279 */
280 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
281 struct sk_buff *skb)
282 {
283 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
284 __wsum csum;
285
286 csum = skb_copy_and_csum_bits(icmp_param->skb,
287 icmp_param->offset + offset,
288 to, len, 0);
289
290 skb->csum = csum_block_add(skb->csum, csum, odd);
291 if (icmp_pointers[icmp_param->data.icmph.type].error)
292 nf_ct_attach(skb, icmp_param->skb);
293 return 0;
294 }
295
296 static void icmp_push_reply(struct icmp_bxm *icmp_param,
297 struct flowi4 *fl4,
298 struct ipcm_cookie *ipc, struct rtable **rt)
299 {
300 struct sock *sk;
301 struct sk_buff *skb;
302
303 sk = icmp_sk(dev_net((*rt)->dst.dev));
304 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
305 icmp_param->data_len+icmp_param->head_len,
306 icmp_param->head_len,
307 ipc, rt, MSG_DONTWAIT) < 0) {
308 ICMP_INC_STATS_BH(sock_net(sk), ICMP_MIB_OUTERRORS);
309 ip_flush_pending_frames(sk);
310 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
311 struct icmphdr *icmph = icmp_hdr(skb);
312 __wsum csum = 0;
313 struct sk_buff *skb1;
314
315 skb_queue_walk(&sk->sk_write_queue, skb1) {
316 csum = csum_add(csum, skb1->csum);
317 }
318 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
319 (char *)icmph,
320 icmp_param->head_len, csum);
321 icmph->checksum = csum_fold(csum);
322 skb->ip_summed = CHECKSUM_NONE;
323 ip_push_pending_frames(sk, fl4);
324 }
325 }
326
327 /*
328 * Driving logic for building and sending ICMP messages.
329 */
330
331 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
332 {
333 struct ipcm_cookie ipc;
334 struct rtable *rt = skb_rtable(skb);
335 struct net *net = dev_net(rt->dst.dev);
336 struct flowi4 fl4;
337 struct sock *sk;
338 struct inet_sock *inet;
339 __be32 daddr, saddr;
340
341 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
342 return;
343
344 sk = icmp_xmit_lock(net);
345 if (sk == NULL)
346 return;
347 inet = inet_sk(sk);
348
349 icmp_param->data.icmph.checksum = 0;
350
351 inet->tos = ip_hdr(skb)->tos;
352 daddr = ipc.addr = ip_hdr(skb)->saddr;
353 saddr = fib_compute_spec_dst(skb);
354 ipc.opt = NULL;
355 ipc.tx_flags = 0;
356 ipc.ttl = 0;
357 ipc.tos = -1;
358
359 if (icmp_param->replyopts.opt.opt.optlen) {
360 ipc.opt = &icmp_param->replyopts.opt;
361 if (ipc.opt->opt.srr)
362 daddr = icmp_param->replyopts.opt.opt.faddr;
363 }
364 memset(&fl4, 0, sizeof(fl4));
365 fl4.daddr = daddr;
366 fl4.saddr = saddr;
367 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
368 fl4.flowi4_proto = IPPROTO_ICMP;
369 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
370 rt = ip_route_output_key(net, &fl4);
371 if (IS_ERR(rt))
372 goto out_unlock;
373 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
374 icmp_param->data.icmph.code))
375 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
376 ip_rt_put(rt);
377 out_unlock:
378 icmp_xmit_unlock(sk);
379 }
380
381 static struct rtable *icmp_route_lookup(struct net *net,
382 struct flowi4 *fl4,
383 struct sk_buff *skb_in,
384 const struct iphdr *iph,
385 __be32 saddr, u8 tos,
386 int type, int code,
387 struct icmp_bxm *param)
388 {
389 struct rtable *rt, *rt2;
390 struct flowi4 fl4_dec;
391 int err;
392
393 memset(fl4, 0, sizeof(*fl4));
394 fl4->daddr = (param->replyopts.opt.opt.srr ?
395 param->replyopts.opt.opt.faddr : iph->saddr);
396 fl4->saddr = saddr;
397 fl4->flowi4_tos = RT_TOS(tos);
398 fl4->flowi4_proto = IPPROTO_ICMP;
399 fl4->fl4_icmp_type = type;
400 fl4->fl4_icmp_code = code;
401 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
402 rt = __ip_route_output_key(net, fl4);
403 if (IS_ERR(rt))
404 return rt;
405
406 /* No need to clone since we're just using its address. */
407 rt2 = rt;
408
409 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
410 flowi4_to_flowi(fl4), NULL, 0);
411 if (!IS_ERR(rt)) {
412 if (rt != rt2)
413 return rt;
414 } else if (PTR_ERR(rt) == -EPERM) {
415 rt = NULL;
416 } else
417 return rt;
418
419 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
420 if (err)
421 goto relookup_failed;
422
423 if (inet_addr_type(net, fl4_dec.saddr) == RTN_LOCAL) {
424 rt2 = __ip_route_output_key(net, &fl4_dec);
425 if (IS_ERR(rt2))
426 err = PTR_ERR(rt2);
427 } else {
428 struct flowi4 fl4_2 = {};
429 unsigned long orefdst;
430
431 fl4_2.daddr = fl4_dec.saddr;
432 rt2 = ip_route_output_key(net, &fl4_2);
433 if (IS_ERR(rt2)) {
434 err = PTR_ERR(rt2);
435 goto relookup_failed;
436 }
437 /* Ugh! */
438 orefdst = skb_in->_skb_refdst; /* save old refdst */
439 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
440 RT_TOS(tos), rt2->dst.dev);
441
442 dst_release(&rt2->dst);
443 rt2 = skb_rtable(skb_in);
444 skb_in->_skb_refdst = orefdst; /* restore old refdst */
445 }
446
447 if (err)
448 goto relookup_failed;
449
450 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
451 flowi4_to_flowi(&fl4_dec), NULL,
452 XFRM_LOOKUP_ICMP);
453 if (!IS_ERR(rt2)) {
454 dst_release(&rt->dst);
455 memcpy(fl4, &fl4_dec, sizeof(*fl4));
456 rt = rt2;
457 } else if (PTR_ERR(rt2) == -EPERM) {
458 if (rt)
459 dst_release(&rt->dst);
460 return rt2;
461 } else {
462 err = PTR_ERR(rt2);
463 goto relookup_failed;
464 }
465 return rt;
466
467 relookup_failed:
468 if (rt)
469 return rt;
470 return ERR_PTR(err);
471 }
472
473 /*
474 * Send an ICMP message in response to a situation
475 *
476 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
477 * MAY send more (we do).
478 * MUST NOT change this header information.
479 * MUST NOT reply to a multicast/broadcast IP address.
480 * MUST NOT reply to a multicast/broadcast MAC address.
481 * MUST reply to only the first fragment.
482 */
483
484 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
485 {
486 struct iphdr *iph;
487 int room;
488 struct icmp_bxm *icmp_param;
489 struct rtable *rt = skb_rtable(skb_in);
490 struct ipcm_cookie ipc;
491 struct flowi4 fl4;
492 __be32 saddr;
493 u8 tos;
494 struct net *net;
495 struct sock *sk;
496
497 if (!rt)
498 goto out;
499 net = dev_net(rt->dst.dev);
500
501 /*
502 * Find the original header. It is expected to be valid, of course.
503 * Check this, icmp_send is called from the most obscure devices
504 * sometimes.
505 */
506 iph = ip_hdr(skb_in);
507
508 if ((u8 *)iph < skb_in->head ||
509 (skb_network_header(skb_in) + sizeof(*iph)) >
510 skb_tail_pointer(skb_in))
511 goto out;
512
513 /*
514 * No replies to physical multicast/broadcast
515 */
516 if (skb_in->pkt_type != PACKET_HOST)
517 goto out;
518
519 /*
520 * Now check at the protocol level
521 */
522 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
523 goto out;
524
525 /*
526 * Only reply to fragment 0. We byte re-order the constant
527 * mask for efficiency.
528 */
529 if (iph->frag_off & htons(IP_OFFSET))
530 goto out;
531
532 /*
533 * If we send an ICMP error to an ICMP error a mess would result..
534 */
535 if (icmp_pointers[type].error) {
536 /*
537 * We are an error, check if we are replying to an
538 * ICMP error
539 */
540 if (iph->protocol == IPPROTO_ICMP) {
541 u8 _inner_type, *itp;
542
543 itp = skb_header_pointer(skb_in,
544 skb_network_header(skb_in) +
545 (iph->ihl << 2) +
546 offsetof(struct icmphdr,
547 type) -
548 skb_in->data,
549 sizeof(_inner_type),
550 &_inner_type);
551 if (itp == NULL)
552 goto out;
553
554 /*
555 * Assume any unknown ICMP type is an error. This
556 * isn't specified by the RFC, but think about it..
557 */
558 if (*itp > NR_ICMP_TYPES ||
559 icmp_pointers[*itp].error)
560 goto out;
561 }
562 }
563
564 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
565 if (!icmp_param)
566 return;
567
568 sk = icmp_xmit_lock(net);
569 if (sk == NULL)
570 goto out_free;
571
572 /*
573 * Construct source address and options.
574 */
575
576 saddr = iph->daddr;
577 if (!(rt->rt_flags & RTCF_LOCAL)) {
578 struct net_device *dev = NULL;
579
580 rcu_read_lock();
581 if (rt_is_input_route(rt) &&
582 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
583 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
584
585 if (dev)
586 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
587 else
588 saddr = 0;
589 rcu_read_unlock();
590 }
591
592 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
593 IPTOS_PREC_INTERNETCONTROL) :
594 iph->tos;
595
596 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
597 goto out_unlock;
598
599
600 /*
601 * Prepare data for ICMP header.
602 */
603
604 icmp_param->data.icmph.type = type;
605 icmp_param->data.icmph.code = code;
606 icmp_param->data.icmph.un.gateway = info;
607 icmp_param->data.icmph.checksum = 0;
608 icmp_param->skb = skb_in;
609 icmp_param->offset = skb_network_offset(skb_in);
610 inet_sk(sk)->tos = tos;
611 ipc.addr = iph->saddr;
612 ipc.opt = &icmp_param->replyopts.opt;
613 ipc.tx_flags = 0;
614 ipc.ttl = 0;
615 ipc.tos = -1;
616
617 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos,
618 type, code, icmp_param);
619 if (IS_ERR(rt))
620 goto out_unlock;
621
622 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
623 goto ende;
624
625 /* RFC says return as much as we can without exceeding 576 bytes. */
626
627 room = dst_mtu(&rt->dst);
628 if (room > 576)
629 room = 576;
630 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
631 room -= sizeof(struct icmphdr);
632
633 icmp_param->data_len = skb_in->len - icmp_param->offset;
634 if (icmp_param->data_len > room)
635 icmp_param->data_len = room;
636 icmp_param->head_len = sizeof(struct icmphdr);
637
638 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
639 ende:
640 ip_rt_put(rt);
641 out_unlock:
642 icmp_xmit_unlock(sk);
643 out_free:
644 kfree(icmp_param);
645 out:;
646 }
647 EXPORT_SYMBOL(icmp_send);
648
649
650 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
651 {
652 const struct iphdr *iph = (const struct iphdr *) skb->data;
653 const struct net_protocol *ipprot;
654 int protocol = iph->protocol;
655
656 /* Checkin full IP header plus 8 bytes of protocol to
657 * avoid additional coding at protocol handlers.
658 */
659 if (!pskb_may_pull(skb, iph->ihl * 4 + 8))
660 return;
661
662 raw_icmp_error(skb, protocol, info);
663
664 rcu_read_lock();
665 ipprot = rcu_dereference(inet_protos[protocol]);
666 if (ipprot && ipprot->err_handler)
667 ipprot->err_handler(skb, info);
668 rcu_read_unlock();
669 }
670
671 /*
672 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, ICMP_QUENCH, and
673 * ICMP_PARAMETERPROB.
674 */
675
676 static void icmp_unreach(struct sk_buff *skb)
677 {
678 const struct iphdr *iph;
679 struct icmphdr *icmph;
680 struct net *net;
681 u32 info = 0;
682
683 net = dev_net(skb_dst(skb)->dev);
684
685 /*
686 * Incomplete header ?
687 * Only checks for the IP header, there should be an
688 * additional check for longer headers in upper levels.
689 */
690
691 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
692 goto out_err;
693
694 icmph = icmp_hdr(skb);
695 iph = (const struct iphdr *)skb->data;
696
697 if (iph->ihl < 5) /* Mangled header, drop. */
698 goto out_err;
699
700 if (icmph->type == ICMP_DEST_UNREACH) {
701 switch (icmph->code & 15) {
702 case ICMP_NET_UNREACH:
703 case ICMP_HOST_UNREACH:
704 case ICMP_PROT_UNREACH:
705 case ICMP_PORT_UNREACH:
706 break;
707 case ICMP_FRAG_NEEDED:
708 if (ipv4_config.no_pmtu_disc) {
709 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: fragmentation needed and DF set\n"),
710 &iph->daddr);
711 } else {
712 info = ntohs(icmph->un.frag.mtu);
713 if (!info)
714 goto out;
715 }
716 break;
717 case ICMP_SR_FAILED:
718 LIMIT_NETDEBUG(KERN_INFO pr_fmt("%pI4: Source Route Failed\n"),
719 &iph->daddr);
720 break;
721 default:
722 break;
723 }
724 if (icmph->code > NR_ICMP_UNREACH)
725 goto out;
726 } else if (icmph->type == ICMP_PARAMETERPROB)
727 info = ntohl(icmph->un.gateway) >> 24;
728
729 /*
730 * Throw it at our lower layers
731 *
732 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
733 * header.
734 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
735 * transport layer.
736 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
737 * transport layer.
738 */
739
740 /*
741 * Check the other end isn't violating RFC 1122. Some routers send
742 * bogus responses to broadcast frames. If you see this message
743 * first check your netmask matches at both ends, if it does then
744 * get the other vendor to fix their kit.
745 */
746
747 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
748 inet_addr_type(net, iph->daddr) == RTN_BROADCAST) {
749 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
750 &ip_hdr(skb)->saddr,
751 icmph->type, icmph->code,
752 &iph->daddr, skb->dev->name);
753 goto out;
754 }
755
756 icmp_socket_deliver(skb, info);
757
758 out:
759 return;
760 out_err:
761 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
762 goto out;
763 }
764
765
766 /*
767 * Handle ICMP_REDIRECT.
768 */
769
770 static void icmp_redirect(struct sk_buff *skb)
771 {
772 if (skb->len < sizeof(struct iphdr)) {
773 ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS);
774 return;
775 }
776
777 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
778 return;
779
780 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
781 }
782
783 /*
784 * Handle ICMP_ECHO ("ping") requests.
785 *
786 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
787 * requests.
788 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
789 * included in the reply.
790 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
791 * echo requests, MUST have default=NOT.
792 * See also WRT handling of options once they are done and working.
793 */
794
795 static void icmp_echo(struct sk_buff *skb)
796 {
797 struct net *net;
798
799 net = dev_net(skb_dst(skb)->dev);
800 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
801 struct icmp_bxm icmp_param;
802
803 icmp_param.data.icmph = *icmp_hdr(skb);
804 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
805 icmp_param.skb = skb;
806 icmp_param.offset = 0;
807 icmp_param.data_len = skb->len;
808 icmp_param.head_len = sizeof(struct icmphdr);
809 icmp_reply(&icmp_param, skb);
810 }
811 }
812
813 /*
814 * Handle ICMP Timestamp requests.
815 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
816 * SHOULD be in the kernel for minimum random latency.
817 * MUST be accurate to a few minutes.
818 * MUST be updated at least at 15Hz.
819 */
820 static void icmp_timestamp(struct sk_buff *skb)
821 {
822 struct timespec tv;
823 struct icmp_bxm icmp_param;
824 /*
825 * Too short.
826 */
827 if (skb->len < 4)
828 goto out_err;
829
830 /*
831 * Fill in the current time as ms since midnight UT:
832 */
833 getnstimeofday(&tv);
834 icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC +
835 tv.tv_nsec / NSEC_PER_MSEC);
836 icmp_param.data.times[2] = icmp_param.data.times[1];
837 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
838 BUG();
839 icmp_param.data.icmph = *icmp_hdr(skb);
840 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
841 icmp_param.data.icmph.code = 0;
842 icmp_param.skb = skb;
843 icmp_param.offset = 0;
844 icmp_param.data_len = 0;
845 icmp_param.head_len = sizeof(struct icmphdr) + 12;
846 icmp_reply(&icmp_param, skb);
847 out:
848 return;
849 out_err:
850 ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
851 goto out;
852 }
853
854 static void icmp_discard(struct sk_buff *skb)
855 {
856 }
857
858 /*
859 * Deal with incoming ICMP packets.
860 */
861 int icmp_rcv(struct sk_buff *skb)
862 {
863 struct icmphdr *icmph;
864 struct rtable *rt = skb_rtable(skb);
865 struct net *net = dev_net(rt->dst.dev);
866
867 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
868 struct sec_path *sp = skb_sec_path(skb);
869 int nh;
870
871 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
872 XFRM_STATE_ICMP))
873 goto drop;
874
875 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
876 goto drop;
877
878 nh = skb_network_offset(skb);
879 skb_set_network_header(skb, sizeof(*icmph));
880
881 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
882 goto drop;
883
884 skb_set_network_header(skb, nh);
885 }
886
887 ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS);
888
889 switch (skb->ip_summed) {
890 case CHECKSUM_COMPLETE:
891 if (!csum_fold(skb->csum))
892 break;
893 /* fall through */
894 case CHECKSUM_NONE:
895 skb->csum = 0;
896 if (__skb_checksum_complete(skb))
897 goto csum_error;
898 }
899
900 if (!pskb_pull(skb, sizeof(*icmph)))
901 goto error;
902
903 icmph = icmp_hdr(skb);
904
905 ICMPMSGIN_INC_STATS_BH(net, icmph->type);
906 /*
907 * 18 is the highest 'known' ICMP type. Anything else is a mystery
908 *
909 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
910 * discarded.
911 */
912 if (icmph->type > NR_ICMP_TYPES)
913 goto error;
914
915
916 /*
917 * Parse the ICMP message
918 */
919
920 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
921 /*
922 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
923 * silently ignored (we let user decide with a sysctl).
924 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
925 * discarded if to broadcast/multicast.
926 */
927 if ((icmph->type == ICMP_ECHO ||
928 icmph->type == ICMP_TIMESTAMP) &&
929 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
930 goto error;
931 }
932 if (icmph->type != ICMP_ECHO &&
933 icmph->type != ICMP_TIMESTAMP &&
934 icmph->type != ICMP_ADDRESS &&
935 icmph->type != ICMP_ADDRESSREPLY) {
936 goto error;
937 }
938 }
939
940 icmp_pointers[icmph->type].handler(skb);
941
942 drop:
943 kfree_skb(skb);
944 return 0;
945 csum_error:
946 ICMP_INC_STATS_BH(net, ICMP_MIB_CSUMERRORS);
947 error:
948 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
949 goto drop;
950 }
951
952 void icmp_err(struct sk_buff *skb, u32 info)
953 {
954 struct iphdr *iph = (struct iphdr *)skb->data;
955 int offset = iph->ihl<<2;
956 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
957 int type = icmp_hdr(skb)->type;
958 int code = icmp_hdr(skb)->code;
959 struct net *net = dev_net(skb->dev);
960
961 /*
962 * Use ping_err to handle all icmp errors except those
963 * triggered by ICMP_ECHOREPLY which sent from kernel.
964 */
965 if (icmph->type != ICMP_ECHOREPLY) {
966 ping_err(skb, offset, info);
967 return;
968 }
969
970 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
971 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
972 else if (type == ICMP_REDIRECT)
973 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
974 }
975
976 /*
977 * This table is the definition of how we handle ICMP.
978 */
979 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
980 [ICMP_ECHOREPLY] = {
981 .handler = ping_rcv,
982 },
983 [1] = {
984 .handler = icmp_discard,
985 .error = 1,
986 },
987 [2] = {
988 .handler = icmp_discard,
989 .error = 1,
990 },
991 [ICMP_DEST_UNREACH] = {
992 .handler = icmp_unreach,
993 .error = 1,
994 },
995 [ICMP_SOURCE_QUENCH] = {
996 .handler = icmp_unreach,
997 .error = 1,
998 },
999 [ICMP_REDIRECT] = {
1000 .handler = icmp_redirect,
1001 .error = 1,
1002 },
1003 [6] = {
1004 .handler = icmp_discard,
1005 .error = 1,
1006 },
1007 [7] = {
1008 .handler = icmp_discard,
1009 .error = 1,
1010 },
1011 [ICMP_ECHO] = {
1012 .handler = icmp_echo,
1013 },
1014 [9] = {
1015 .handler = icmp_discard,
1016 .error = 1,
1017 },
1018 [10] = {
1019 .handler = icmp_discard,
1020 .error = 1,
1021 },
1022 [ICMP_TIME_EXCEEDED] = {
1023 .handler = icmp_unreach,
1024 .error = 1,
1025 },
1026 [ICMP_PARAMETERPROB] = {
1027 .handler = icmp_unreach,
1028 .error = 1,
1029 },
1030 [ICMP_TIMESTAMP] = {
1031 .handler = icmp_timestamp,
1032 },
1033 [ICMP_TIMESTAMPREPLY] = {
1034 .handler = icmp_discard,
1035 },
1036 [ICMP_INFO_REQUEST] = {
1037 .handler = icmp_discard,
1038 },
1039 [ICMP_INFO_REPLY] = {
1040 .handler = icmp_discard,
1041 },
1042 [ICMP_ADDRESS] = {
1043 .handler = icmp_discard,
1044 },
1045 [ICMP_ADDRESSREPLY] = {
1046 .handler = icmp_discard,
1047 },
1048 };
1049
1050 static void __net_exit icmp_sk_exit(struct net *net)
1051 {
1052 int i;
1053
1054 for_each_possible_cpu(i)
1055 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1056 kfree(net->ipv4.icmp_sk);
1057 net->ipv4.icmp_sk = NULL;
1058 }
1059
1060 static int __net_init icmp_sk_init(struct net *net)
1061 {
1062 int i, err;
1063
1064 net->ipv4.icmp_sk =
1065 kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
1066 if (net->ipv4.icmp_sk == NULL)
1067 return -ENOMEM;
1068
1069 for_each_possible_cpu(i) {
1070 struct sock *sk;
1071
1072 err = inet_ctl_sock_create(&sk, PF_INET,
1073 SOCK_RAW, IPPROTO_ICMP, net);
1074 if (err < 0)
1075 goto fail;
1076
1077 net->ipv4.icmp_sk[i] = sk;
1078
1079 /* Enough space for 2 64K ICMP packets, including
1080 * sk_buff/skb_shared_info struct overhead.
1081 */
1082 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1083
1084 /*
1085 * Speedup sock_wfree()
1086 */
1087 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1088 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1089 }
1090
1091 /* Control parameters for ECHO replies. */
1092 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1093 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1094
1095 /* Control parameter - ignore bogus broadcast responses? */
1096 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1097
1098 /*
1099 * Configurable global rate limit.
1100 *
1101 * ratelimit defines tokens/packet consumed for dst->rate_token
1102 * bucket ratemask defines which icmp types are ratelimited by
1103 * setting it's bit position.
1104 *
1105 * default:
1106 * dest unreachable (3), source quench (4),
1107 * time exceeded (11), parameter problem (12)
1108 */
1109
1110 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1111 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1112 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1113
1114 return 0;
1115
1116 fail:
1117 for_each_possible_cpu(i)
1118 inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]);
1119 kfree(net->ipv4.icmp_sk);
1120 return err;
1121 }
1122
1123 static struct pernet_operations __net_initdata icmp_sk_ops = {
1124 .init = icmp_sk_init,
1125 .exit = icmp_sk_exit,
1126 };
1127
1128 int __init icmp_init(void)
1129 {
1130 return register_pernet_subsys(&icmp_sk_ops);
1131 }
Linus' kernel tree