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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 replyopts; |
112 | unsigned char optbuf[40]; |
113 | }; |
114 | |
115 | /* An array of errno for error messages from dest unreach. */ |
116 | /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */ |
117 | |
118 | const struct icmp_err icmp_err_convert[] = { |
119 | { |
120 | .errno = ENETUNREACH, /* ICMP_NET_UNREACH */ |
121 | .fatal = 0, |
122 | }, |
123 | { |
124 | .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */ |
125 | .fatal = 0, |
126 | }, |
127 | { |
128 | .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */, |
129 | .fatal = 1, |
130 | }, |
131 | { |
132 | .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */ |
133 | .fatal = 1, |
134 | }, |
135 | { |
136 | .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */ |
137 | .fatal = 0, |
138 | }, |
139 | { |
140 | .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */ |
141 | .fatal = 0, |
142 | }, |
143 | { |
144 | .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */ |
145 | .fatal = 1, |
146 | }, |
147 | { |
148 | .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */ |
149 | .fatal = 1, |
150 | }, |
151 | { |
152 | .errno = ENONET, /* ICMP_HOST_ISOLATED */ |
153 | .fatal = 1, |
154 | }, |
155 | { |
156 | .errno = ENETUNREACH, /* ICMP_NET_ANO */ |
157 | .fatal = 1, |
158 | }, |
159 | { |
160 | .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */ |
161 | .fatal = 1, |
162 | }, |
163 | { |
164 | .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */ |
165 | .fatal = 0, |
166 | }, |
167 | { |
168 | .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */ |
169 | .fatal = 0, |
170 | }, |
171 | { |
172 | .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */ |
173 | .fatal = 1, |
174 | }, |
175 | { |
176 | .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */ |
177 | .fatal = 1, |
178 | }, |
179 | { |
180 | .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */ |
181 | .fatal = 1, |
182 | }, |
183 | }; |
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 | /* |
236 | * Check transmit rate limitation for given message. |
237 | * The rate information is held in the destination cache now. |
238 | * This function is generic and could be used for other purposes |
239 | * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. |
240 | * |
241 | * Note that the same dst_entry fields are modified by functions in |
242 | * route.c too, but these work for packet destinations while xrlim_allow |
243 | * works for icmp destinations. This means the rate limiting information |
244 | * for one "ip object" is shared - and these ICMPs are twice limited: |
245 | * by source and by destination. |
246 | * |
247 | * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate |
248 | * SHOULD allow setting of rate limits |
249 | * |
250 | * Shared between ICMPv4 and ICMPv6. |
251 | */ |
252 | #define XRLIM_BURST_FACTOR 6 |
253 | int xrlim_allow(struct dst_entry *dst, int timeout) |
254 | { |
255 | unsigned long now, token = dst->rate_tokens; |
256 | int rc = 0; |
257 | |
258 | now = jiffies; |
259 | token += now - dst->rate_last; |
260 | dst->rate_last = now; |
261 | if (token > XRLIM_BURST_FACTOR * timeout) |
262 | token = XRLIM_BURST_FACTOR * timeout; |
263 | if (token >= timeout) { |
264 | token -= timeout; |
265 | rc = 1; |
266 | } |
267 | dst->rate_tokens = token; |
268 | return rc; |
269 | } |
270 | |
271 | static inline int icmpv4_xrlim_allow(struct net *net, struct rtable *rt, |
272 | int type, int code) |
273 | { |
274 | struct dst_entry *dst = &rt->u.dst; |
275 | int rc = 1; |
276 | |
277 | if (type > NR_ICMP_TYPES) |
278 | goto out; |
279 | |
280 | /* Don't limit PMTU discovery. */ |
281 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) |
282 | goto out; |
283 | |
284 | /* No rate limit on loopback */ |
285 | if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) |
286 | goto out; |
287 | |
288 | /* Limit if icmp type is enabled in ratemask. */ |
289 | if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) |
290 | rc = xrlim_allow(dst, net->ipv4.sysctl_icmp_ratelimit); |
291 | out: |
292 | return rc; |
293 | } |
294 | |
295 | /* |
296 | * Maintain the counters used in the SNMP statistics for outgoing ICMP |
297 | */ |
298 | void icmp_out_count(struct net *net, unsigned char type) |
299 | { |
300 | ICMPMSGOUT_INC_STATS(net, type); |
301 | ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); |
302 | } |
303 | |
304 | /* |
305 | * Checksum each fragment, and on the first include the headers and final |
306 | * checksum. |
307 | */ |
308 | static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, |
309 | struct sk_buff *skb) |
310 | { |
311 | struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; |
312 | __wsum csum; |
313 | |
314 | csum = skb_copy_and_csum_bits(icmp_param->skb, |
315 | icmp_param->offset + offset, |
316 | to, len, 0); |
317 | |
318 | skb->csum = csum_block_add(skb->csum, csum, odd); |
319 | if (icmp_pointers[icmp_param->data.icmph.type].error) |
320 | nf_ct_attach(skb, icmp_param->skb); |
321 | return 0; |
322 | } |
323 | |
324 | static void icmp_push_reply(struct icmp_bxm *icmp_param, |
325 | struct ipcm_cookie *ipc, struct rtable **rt) |
326 | { |
327 | struct sock *sk; |
328 | struct sk_buff *skb; |
329 | |
330 | sk = icmp_sk(dev_net((*rt)->u.dst.dev)); |
331 | if (ip_append_data(sk, icmp_glue_bits, icmp_param, |
332 | icmp_param->data_len+icmp_param->head_len, |
333 | icmp_param->head_len, |
334 | ipc, rt, MSG_DONTWAIT) < 0) |
335 | ip_flush_pending_frames(sk); |
336 | else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) { |
337 | struct icmphdr *icmph = icmp_hdr(skb); |
338 | __wsum csum = 0; |
339 | struct sk_buff *skb1; |
340 | |
341 | skb_queue_walk(&sk->sk_write_queue, skb1) { |
342 | csum = csum_add(csum, skb1->csum); |
343 | } |
344 | csum = csum_partial_copy_nocheck((void *)&icmp_param->data, |
345 | (char *)icmph, |
346 | icmp_param->head_len, csum); |
347 | icmph->checksum = csum_fold(csum); |
348 | skb->ip_summed = CHECKSUM_NONE; |
349 | ip_push_pending_frames(sk); |
350 | } |
351 | } |
352 | |
353 | /* |
354 | * Driving logic for building and sending ICMP messages. |
355 | */ |
356 | |
357 | static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) |
358 | { |
359 | struct ipcm_cookie ipc; |
360 | struct rtable *rt = skb_rtable(skb); |
361 | struct net *net = dev_net(rt->u.dst.dev); |
362 | struct sock *sk; |
363 | struct inet_sock *inet; |
364 | __be32 daddr; |
365 | |
366 | if (ip_options_echo(&icmp_param->replyopts, skb)) |
367 | return; |
368 | |
369 | sk = icmp_xmit_lock(net); |
370 | if (sk == NULL) |
371 | return; |
372 | inet = inet_sk(sk); |
373 | |
374 | icmp_param->data.icmph.checksum = 0; |
375 | |
376 | inet->tos = ip_hdr(skb)->tos; |
377 | daddr = ipc.addr = rt->rt_src; |
378 | ipc.opt = NULL; |
379 | ipc.shtx.flags = 0; |
380 | if (icmp_param->replyopts.optlen) { |
381 | ipc.opt = &icmp_param->replyopts; |
382 | if (ipc.opt->srr) |
383 | daddr = icmp_param->replyopts.faddr; |
384 | } |
385 | { |
386 | struct flowi fl = { .nl_u = { .ip4_u = |
387 | { .daddr = daddr, |
388 | .saddr = rt->rt_spec_dst, |
389 | .tos = RT_TOS(ip_hdr(skb)->tos) } }, |
390 | .proto = IPPROTO_ICMP }; |
391 | security_skb_classify_flow(skb, &fl); |
392 | if (ip_route_output_key(net, &rt, &fl)) |
393 | goto out_unlock; |
394 | } |
395 | if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type, |
396 | icmp_param->data.icmph.code)) |
397 | icmp_push_reply(icmp_param, &ipc, &rt); |
398 | ip_rt_put(rt); |
399 | out_unlock: |
400 | icmp_xmit_unlock(sk); |
401 | } |
402 | |
403 | |
404 | /* |
405 | * Send an ICMP message in response to a situation |
406 | * |
407 | * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. |
408 | * MAY send more (we do). |
409 | * MUST NOT change this header information. |
410 | * MUST NOT reply to a multicast/broadcast IP address. |
411 | * MUST NOT reply to a multicast/broadcast MAC address. |
412 | * MUST reply to only the first fragment. |
413 | */ |
414 | |
415 | void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) |
416 | { |
417 | struct iphdr *iph; |
418 | int room; |
419 | struct icmp_bxm icmp_param; |
420 | struct rtable *rt = skb_rtable(skb_in); |
421 | struct ipcm_cookie ipc; |
422 | __be32 saddr; |
423 | u8 tos; |
424 | struct net *net; |
425 | struct sock *sk; |
426 | |
427 | if (!rt) |
428 | goto out; |
429 | net = dev_net(rt->u.dst.dev); |
430 | |
431 | /* |
432 | * Find the original header. It is expected to be valid, of course. |
433 | * Check this, icmp_send is called from the most obscure devices |
434 | * sometimes. |
435 | */ |
436 | iph = ip_hdr(skb_in); |
437 | |
438 | if ((u8 *)iph < skb_in->head || |
439 | (skb_in->network_header + sizeof(*iph)) > skb_in->tail) |
440 | goto out; |
441 | |
442 | /* |
443 | * No replies to physical multicast/broadcast |
444 | */ |
445 | if (skb_in->pkt_type != PACKET_HOST) |
446 | goto out; |
447 | |
448 | /* |
449 | * Now check at the protocol level |
450 | */ |
451 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) |
452 | goto out; |
453 | |
454 | /* |
455 | * Only reply to fragment 0. We byte re-order the constant |
456 | * mask for efficiency. |
457 | */ |
458 | if (iph->frag_off & htons(IP_OFFSET)) |
459 | goto out; |
460 | |
461 | /* |
462 | * If we send an ICMP error to an ICMP error a mess would result.. |
463 | */ |
464 | if (icmp_pointers[type].error) { |
465 | /* |
466 | * We are an error, check if we are replying to an |
467 | * ICMP error |
468 | */ |
469 | if (iph->protocol == IPPROTO_ICMP) { |
470 | u8 _inner_type, *itp; |
471 | |
472 | itp = skb_header_pointer(skb_in, |
473 | skb_network_header(skb_in) + |
474 | (iph->ihl << 2) + |
475 | offsetof(struct icmphdr, |
476 | type) - |
477 | skb_in->data, |
478 | sizeof(_inner_type), |
479 | &_inner_type); |
480 | if (itp == NULL) |
481 | goto out; |
482 | |
483 | /* |
484 | * Assume any unknown ICMP type is an error. This |
485 | * isn't specified by the RFC, but think about it.. |
486 | */ |
487 | if (*itp > NR_ICMP_TYPES || |
488 | icmp_pointers[*itp].error) |
489 | goto out; |
490 | } |
491 | } |
492 | |
493 | sk = icmp_xmit_lock(net); |
494 | if (sk == NULL) |
495 | return; |
496 | |
497 | /* |
498 | * Construct source address and options. |
499 | */ |
500 | |
501 | saddr = iph->daddr; |
502 | if (!(rt->rt_flags & RTCF_LOCAL)) { |
503 | struct net_device *dev = NULL; |
504 | |
505 | rcu_read_lock(); |
506 | if (rt->fl.iif && |
507 | net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) |
508 | dev = dev_get_by_index_rcu(net, rt->fl.iif); |
509 | |
510 | if (dev) |
511 | saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); |
512 | else |
513 | saddr = 0; |
514 | rcu_read_unlock(); |
515 | } |
516 | |
517 | tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | |
518 | IPTOS_PREC_INTERNETCONTROL) : |
519 | iph->tos; |
520 | |
521 | if (ip_options_echo(&icmp_param.replyopts, skb_in)) |
522 | goto out_unlock; |
523 | |
524 | |
525 | /* |
526 | * Prepare data for ICMP header. |
527 | */ |
528 | |
529 | icmp_param.data.icmph.type = type; |
530 | icmp_param.data.icmph.code = code; |
531 | icmp_param.data.icmph.un.gateway = info; |
532 | icmp_param.data.icmph.checksum = 0; |
533 | icmp_param.skb = skb_in; |
534 | icmp_param.offset = skb_network_offset(skb_in); |
535 | inet_sk(sk)->tos = tos; |
536 | ipc.addr = iph->saddr; |
537 | ipc.opt = &icmp_param.replyopts; |
538 | ipc.shtx.flags = 0; |
539 | |
540 | { |
541 | struct flowi fl = { |
542 | .nl_u = { |
543 | .ip4_u = { |
544 | .daddr = icmp_param.replyopts.srr ? |
545 | icmp_param.replyopts.faddr : |
546 | iph->saddr, |
547 | .saddr = saddr, |
548 | .tos = RT_TOS(tos) |
549 | } |
550 | }, |
551 | .proto = IPPROTO_ICMP, |
552 | .uli_u = { |
553 | .icmpt = { |
554 | .type = type, |
555 | .code = code |
556 | } |
557 | } |
558 | }; |
559 | int err; |
560 | struct rtable *rt2; |
561 | |
562 | security_skb_classify_flow(skb_in, &fl); |
563 | if (__ip_route_output_key(net, &rt, &fl)) |
564 | goto out_unlock; |
565 | |
566 | /* No need to clone since we're just using its address. */ |
567 | rt2 = rt; |
568 | |
569 | err = xfrm_lookup(net, (struct dst_entry **)&rt, &fl, NULL, 0); |
570 | switch (err) { |
571 | case 0: |
572 | if (rt != rt2) |
573 | goto route_done; |
574 | break; |
575 | case -EPERM: |
576 | rt = NULL; |
577 | break; |
578 | default: |
579 | goto out_unlock; |
580 | } |
581 | |
582 | if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET)) |
583 | goto relookup_failed; |
584 | |
585 | if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL) |
586 | err = __ip_route_output_key(net, &rt2, &fl); |
587 | else { |
588 | struct flowi fl2 = {}; |
589 | struct dst_entry *odst; |
590 | |
591 | fl2.fl4_dst = fl.fl4_src; |
592 | if (ip_route_output_key(net, &rt2, &fl2)) |
593 | goto relookup_failed; |
594 | |
595 | /* Ugh! */ |
596 | odst = skb_dst(skb_in); |
597 | err = ip_route_input(skb_in, fl.fl4_dst, fl.fl4_src, |
598 | RT_TOS(tos), rt2->u.dst.dev); |
599 | |
600 | dst_release(&rt2->u.dst); |
601 | rt2 = skb_rtable(skb_in); |
602 | skb_dst_set(skb_in, odst); |
603 | } |
604 | |
605 | if (err) |
606 | goto relookup_failed; |
607 | |
608 | err = xfrm_lookup(net, (struct dst_entry **)&rt2, &fl, NULL, |
609 | XFRM_LOOKUP_ICMP); |
610 | switch (err) { |
611 | case 0: |
612 | dst_release(&rt->u.dst); |
613 | rt = rt2; |
614 | break; |
615 | case -EPERM: |
616 | goto ende; |
617 | default: |
618 | relookup_failed: |
619 | if (!rt) |
620 | goto out_unlock; |
621 | break; |
622 | } |
623 | } |
624 | |
625 | route_done: |
626 | if (!icmpv4_xrlim_allow(net, rt, type, code)) |
627 | goto ende; |
628 | |
629 | /* RFC says return as much as we can without exceeding 576 bytes. */ |
630 | |
631 | room = dst_mtu(&rt->u.dst); |
632 | if (room > 576) |
633 | room = 576; |
634 | room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; |
635 | room -= sizeof(struct icmphdr); |
636 | |
637 | icmp_param.data_len = skb_in->len - icmp_param.offset; |
638 | if (icmp_param.data_len > room) |
639 | icmp_param.data_len = room; |
640 | icmp_param.head_len = sizeof(struct icmphdr); |
641 | |
642 | icmp_push_reply(&icmp_param, &ipc, &rt); |
643 | ende: |
644 | ip_rt_put(rt); |
645 | out_unlock: |
646 | icmp_xmit_unlock(sk); |
647 | out:; |
648 | } |
649 | |
650 | |
651 | /* |
652 | * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. |
653 | */ |
654 | |
655 | static void icmp_unreach(struct sk_buff *skb) |
656 | { |
657 | struct iphdr *iph; |
658 | struct icmphdr *icmph; |
659 | int hash, protocol; |
660 | const struct net_protocol *ipprot; |
661 | u32 info = 0; |
662 | struct net *net; |
663 | |
664 | net = dev_net(skb_dst(skb)->dev); |
665 | |
666 | /* |
667 | * Incomplete header ? |
668 | * Only checks for the IP header, there should be an |
669 | * additional check for longer headers in upper levels. |
670 | */ |
671 | |
672 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
673 | goto out_err; |
674 | |
675 | icmph = icmp_hdr(skb); |
676 | iph = (struct iphdr *)skb->data; |
677 | |
678 | if (iph->ihl < 5) /* Mangled header, drop. */ |
679 | goto out_err; |
680 | |
681 | if (icmph->type == ICMP_DEST_UNREACH) { |
682 | switch (icmph->code & 15) { |
683 | case ICMP_NET_UNREACH: |
684 | case ICMP_HOST_UNREACH: |
685 | case ICMP_PROT_UNREACH: |
686 | case ICMP_PORT_UNREACH: |
687 | break; |
688 | case ICMP_FRAG_NEEDED: |
689 | if (ipv4_config.no_pmtu_disc) { |
690 | LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n", |
691 | &iph->daddr); |
692 | } else { |
693 | info = ip_rt_frag_needed(net, iph, |
694 | ntohs(icmph->un.frag.mtu), |
695 | skb->dev); |
696 | if (!info) |
697 | goto out; |
698 | } |
699 | break; |
700 | case ICMP_SR_FAILED: |
701 | LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n", |
702 | &iph->daddr); |
703 | break; |
704 | default: |
705 | break; |
706 | } |
707 | if (icmph->code > NR_ICMP_UNREACH) |
708 | goto out; |
709 | } else if (icmph->type == ICMP_PARAMETERPROB) |
710 | info = ntohl(icmph->un.gateway) >> 24; |
711 | |
712 | /* |
713 | * Throw it at our lower layers |
714 | * |
715 | * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed |
716 | * header. |
717 | * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the |
718 | * transport layer. |
719 | * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to |
720 | * transport layer. |
721 | */ |
722 | |
723 | /* |
724 | * Check the other end isnt violating RFC 1122. Some routers send |
725 | * bogus responses to broadcast frames. If you see this message |
726 | * first check your netmask matches at both ends, if it does then |
727 | * get the other vendor to fix their kit. |
728 | */ |
729 | |
730 | if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && |
731 | inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { |
732 | if (net_ratelimit()) |
733 | printk(KERN_WARNING "%pI4 sent an invalid ICMP " |
734 | "type %u, code %u " |
735 | "error to a broadcast: %pI4 on %s\n", |
736 | &ip_hdr(skb)->saddr, |
737 | icmph->type, icmph->code, |
738 | &iph->daddr, |
739 | skb->dev->name); |
740 | goto out; |
741 | } |
742 | |
743 | /* Checkin full IP header plus 8 bytes of protocol to |
744 | * avoid additional coding at protocol handlers. |
745 | */ |
746 | if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) |
747 | goto out; |
748 | |
749 | iph = (struct iphdr *)skb->data; |
750 | protocol = iph->protocol; |
751 | |
752 | /* |
753 | * Deliver ICMP message to raw sockets. Pretty useless feature? |
754 | */ |
755 | raw_icmp_error(skb, protocol, info); |
756 | |
757 | hash = protocol & (MAX_INET_PROTOS - 1); |
758 | rcu_read_lock(); |
759 | ipprot = rcu_dereference(inet_protos[hash]); |
760 | if (ipprot && ipprot->err_handler) |
761 | ipprot->err_handler(skb, info); |
762 | rcu_read_unlock(); |
763 | |
764 | out: |
765 | return; |
766 | out_err: |
767 | ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); |
768 | goto out; |
769 | } |
770 | |
771 | |
772 | /* |
773 | * Handle ICMP_REDIRECT. |
774 | */ |
775 | |
776 | static void icmp_redirect(struct sk_buff *skb) |
777 | { |
778 | struct iphdr *iph; |
779 | |
780 | if (skb->len < sizeof(struct iphdr)) |
781 | goto out_err; |
782 | |
783 | /* |
784 | * Get the copied header of the packet that caused the redirect |
785 | */ |
786 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
787 | goto out; |
788 | |
789 | iph = (struct iphdr *)skb->data; |
790 | |
791 | switch (icmp_hdr(skb)->code & 7) { |
792 | case ICMP_REDIR_NET: |
793 | case ICMP_REDIR_NETTOS: |
794 | /* |
795 | * As per RFC recommendations now handle it as a host redirect. |
796 | */ |
797 | case ICMP_REDIR_HOST: |
798 | case ICMP_REDIR_HOSTTOS: |
799 | ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, |
800 | icmp_hdr(skb)->un.gateway, |
801 | iph->saddr, skb->dev); |
802 | break; |
803 | } |
804 | out: |
805 | return; |
806 | out_err: |
807 | ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); |
808 | goto out; |
809 | } |
810 | |
811 | /* |
812 | * Handle ICMP_ECHO ("ping") requests. |
813 | * |
814 | * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo |
815 | * requests. |
816 | * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be |
817 | * included in the reply. |
818 | * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring |
819 | * echo requests, MUST have default=NOT. |
820 | * See also WRT handling of options once they are done and working. |
821 | */ |
822 | |
823 | static void icmp_echo(struct sk_buff *skb) |
824 | { |
825 | struct net *net; |
826 | |
827 | net = dev_net(skb_dst(skb)->dev); |
828 | if (!net->ipv4.sysctl_icmp_echo_ignore_all) { |
829 | struct icmp_bxm icmp_param; |
830 | |
831 | icmp_param.data.icmph = *icmp_hdr(skb); |
832 | icmp_param.data.icmph.type = ICMP_ECHOREPLY; |
833 | icmp_param.skb = skb; |
834 | icmp_param.offset = 0; |
835 | icmp_param.data_len = skb->len; |
836 | icmp_param.head_len = sizeof(struct icmphdr); |
837 | icmp_reply(&icmp_param, skb); |
838 | } |
839 | } |
840 | |
841 | /* |
842 | * Handle ICMP Timestamp requests. |
843 | * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. |
844 | * SHOULD be in the kernel for minimum random latency. |
845 | * MUST be accurate to a few minutes. |
846 | * MUST be updated at least at 15Hz. |
847 | */ |
848 | static void icmp_timestamp(struct sk_buff *skb) |
849 | { |
850 | struct timespec tv; |
851 | struct icmp_bxm icmp_param; |
852 | /* |
853 | * Too short. |
854 | */ |
855 | if (skb->len < 4) |
856 | goto out_err; |
857 | |
858 | /* |
859 | * Fill in the current time as ms since midnight UT: |
860 | */ |
861 | getnstimeofday(&tv); |
862 | icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + |
863 | tv.tv_nsec / NSEC_PER_MSEC); |
864 | icmp_param.data.times[2] = icmp_param.data.times[1]; |
865 | if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) |
866 | BUG(); |
867 | icmp_param.data.icmph = *icmp_hdr(skb); |
868 | icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; |
869 | icmp_param.data.icmph.code = 0; |
870 | icmp_param.skb = skb; |
871 | icmp_param.offset = 0; |
872 | icmp_param.data_len = 0; |
873 | icmp_param.head_len = sizeof(struct icmphdr) + 12; |
874 | icmp_reply(&icmp_param, skb); |
875 | out: |
876 | return; |
877 | out_err: |
878 | ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); |
879 | goto out; |
880 | } |
881 | |
882 | |
883 | /* |
884 | * Handle ICMP_ADDRESS_MASK requests. (RFC950) |
885 | * |
886 | * RFC1122 (3.2.2.9). A host MUST only send replies to |
887 | * ADDRESS_MASK requests if it's been configured as an address mask |
888 | * agent. Receiving a request doesn't constitute implicit permission to |
889 | * act as one. Of course, implementing this correctly requires (SHOULD) |
890 | * a way to turn the functionality on and off. Another one for sysctl(), |
891 | * I guess. -- MS |
892 | * |
893 | * RFC1812 (4.3.3.9). A router MUST implement it. |
894 | * A router SHOULD have switch turning it on/off. |
895 | * This switch MUST be ON by default. |
896 | * |
897 | * Gratuitous replies, zero-source replies are not implemented, |
898 | * that complies with RFC. DO NOT implement them!!! All the idea |
899 | * of broadcast addrmask replies as specified in RFC950 is broken. |
900 | * The problem is that it is not uncommon to have several prefixes |
901 | * on one physical interface. Moreover, addrmask agent can even be |
902 | * not aware of existing another prefixes. |
903 | * If source is zero, addrmask agent cannot choose correct prefix. |
904 | * Gratuitous mask announcements suffer from the same problem. |
905 | * RFC1812 explains it, but still allows to use ADDRMASK, |
906 | * that is pretty silly. --ANK |
907 | * |
908 | * All these rules are so bizarre, that I removed kernel addrmask |
909 | * support at all. It is wrong, it is obsolete, nobody uses it in |
910 | * any case. --ANK |
911 | * |
912 | * Furthermore you can do it with a usermode address agent program |
913 | * anyway... |
914 | */ |
915 | |
916 | static void icmp_address(struct sk_buff *skb) |
917 | { |
918 | #if 0 |
919 | if (net_ratelimit()) |
920 | printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n"); |
921 | #endif |
922 | } |
923 | |
924 | /* |
925 | * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain |
926 | * loudly if an inconsistency is found. |
927 | */ |
928 | |
929 | static void icmp_address_reply(struct sk_buff *skb) |
930 | { |
931 | struct rtable *rt = skb_rtable(skb); |
932 | struct net_device *dev = skb->dev; |
933 | struct in_device *in_dev; |
934 | struct in_ifaddr *ifa; |
935 | |
936 | if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) |
937 | goto out; |
938 | |
939 | in_dev = in_dev_get(dev); |
940 | if (!in_dev) |
941 | goto out; |
942 | rcu_read_lock(); |
943 | if (in_dev->ifa_list && |
944 | IN_DEV_LOG_MARTIANS(in_dev) && |
945 | IN_DEV_FORWARD(in_dev)) { |
946 | __be32 _mask, *mp; |
947 | |
948 | mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); |
949 | BUG_ON(mp == NULL); |
950 | for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { |
951 | if (*mp == ifa->ifa_mask && |
952 | inet_ifa_match(rt->rt_src, ifa)) |
953 | break; |
954 | } |
955 | if (!ifa && net_ratelimit()) { |
956 | printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n", |
957 | mp, dev->name, &rt->rt_src); |
958 | } |
959 | } |
960 | rcu_read_unlock(); |
961 | in_dev_put(in_dev); |
962 | out:; |
963 | } |
964 | |
965 | static void icmp_discard(struct sk_buff *skb) |
966 | { |
967 | } |
968 | |
969 | /* |
970 | * Deal with incoming ICMP packets. |
971 | */ |
972 | int icmp_rcv(struct sk_buff *skb) |
973 | { |
974 | struct icmphdr *icmph; |
975 | struct rtable *rt = skb_rtable(skb); |
976 | struct net *net = dev_net(rt->u.dst.dev); |
977 | |
978 | if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
979 | struct sec_path *sp = skb_sec_path(skb); |
980 | int nh; |
981 | |
982 | if (!(sp && sp->xvec[sp->len - 1]->props.flags & |
983 | XFRM_STATE_ICMP)) |
984 | goto drop; |
985 | |
986 | if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) |
987 | goto drop; |
988 | |
989 | nh = skb_network_offset(skb); |
990 | skb_set_network_header(skb, sizeof(*icmph)); |
991 | |
992 | if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) |
993 | goto drop; |
994 | |
995 | skb_set_network_header(skb, nh); |
996 | } |
997 | |
998 | ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); |
999 | |
1000 | switch (skb->ip_summed) { |
1001 | case CHECKSUM_COMPLETE: |
1002 | if (!csum_fold(skb->csum)) |
1003 | break; |
1004 | /* fall through */ |
1005 | case CHECKSUM_NONE: |
1006 | skb->csum = 0; |
1007 | if (__skb_checksum_complete(skb)) |
1008 | goto error; |
1009 | } |
1010 | |
1011 | if (!pskb_pull(skb, sizeof(*icmph))) |
1012 | goto error; |
1013 | |
1014 | icmph = icmp_hdr(skb); |
1015 | |
1016 | ICMPMSGIN_INC_STATS_BH(net, icmph->type); |
1017 | /* |
1018 | * 18 is the highest 'known' ICMP type. Anything else is a mystery |
1019 | * |
1020 | * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently |
1021 | * discarded. |
1022 | */ |
1023 | if (icmph->type > NR_ICMP_TYPES) |
1024 | goto error; |
1025 | |
1026 | |
1027 | /* |
1028 | * Parse the ICMP message |
1029 | */ |
1030 | |
1031 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { |
1032 | /* |
1033 | * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be |
1034 | * silently ignored (we let user decide with a sysctl). |
1035 | * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently |
1036 | * discarded if to broadcast/multicast. |
1037 | */ |
1038 | if ((icmph->type == ICMP_ECHO || |
1039 | icmph->type == ICMP_TIMESTAMP) && |
1040 | net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { |
1041 | goto error; |
1042 | } |
1043 | if (icmph->type != ICMP_ECHO && |
1044 | icmph->type != ICMP_TIMESTAMP && |
1045 | icmph->type != ICMP_ADDRESS && |
1046 | icmph->type != ICMP_ADDRESSREPLY) { |
1047 | goto error; |
1048 | } |
1049 | } |
1050 | |
1051 | icmp_pointers[icmph->type].handler(skb); |
1052 | |
1053 | drop: |
1054 | kfree_skb(skb); |
1055 | return 0; |
1056 | error: |
1057 | ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); |
1058 | goto drop; |
1059 | } |
1060 | |
1061 | /* |
1062 | * This table is the definition of how we handle ICMP. |
1063 | */ |
1064 | static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { |
1065 | [ICMP_ECHOREPLY] = { |
1066 | .handler = icmp_discard, |
1067 | }, |
1068 | [1] = { |
1069 | .handler = icmp_discard, |
1070 | .error = 1, |
1071 | }, |
1072 | [2] = { |
1073 | .handler = icmp_discard, |
1074 | .error = 1, |
1075 | }, |
1076 | [ICMP_DEST_UNREACH] = { |
1077 | .handler = icmp_unreach, |
1078 | .error = 1, |
1079 | }, |
1080 | [ICMP_SOURCE_QUENCH] = { |
1081 | .handler = icmp_unreach, |
1082 | .error = 1, |
1083 | }, |
1084 | [ICMP_REDIRECT] = { |
1085 | .handler = icmp_redirect, |
1086 | .error = 1, |
1087 | }, |
1088 | [6] = { |
1089 | .handler = icmp_discard, |
1090 | .error = 1, |
1091 | }, |
1092 | [7] = { |
1093 | .handler = icmp_discard, |
1094 | .error = 1, |
1095 | }, |
1096 | [ICMP_ECHO] = { |
1097 | .handler = icmp_echo, |
1098 | }, |
1099 | [9] = { |
1100 | .handler = icmp_discard, |
1101 | .error = 1, |
1102 | }, |
1103 | [10] = { |
1104 | .handler = icmp_discard, |
1105 | .error = 1, |
1106 | }, |
1107 | [ICMP_TIME_EXCEEDED] = { |
1108 | .handler = icmp_unreach, |
1109 | .error = 1, |
1110 | }, |
1111 | [ICMP_PARAMETERPROB] = { |
1112 | .handler = icmp_unreach, |
1113 | .error = 1, |
1114 | }, |
1115 | [ICMP_TIMESTAMP] = { |
1116 | .handler = icmp_timestamp, |
1117 | }, |
1118 | [ICMP_TIMESTAMPREPLY] = { |
1119 | .handler = icmp_discard, |
1120 | }, |
1121 | [ICMP_INFO_REQUEST] = { |
1122 | .handler = icmp_discard, |
1123 | }, |
1124 | [ICMP_INFO_REPLY] = { |
1125 | .handler = icmp_discard, |
1126 | }, |
1127 | [ICMP_ADDRESS] = { |
1128 | .handler = icmp_address, |
1129 | }, |
1130 | [ICMP_ADDRESSREPLY] = { |
1131 | .handler = icmp_address_reply, |
1132 | }, |
1133 | }; |
1134 | |
1135 | static void __net_exit icmp_sk_exit(struct net *net) |
1136 | { |
1137 | int i; |
1138 | |
1139 | for_each_possible_cpu(i) |
1140 | inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); |
1141 | kfree(net->ipv4.icmp_sk); |
1142 | net->ipv4.icmp_sk = NULL; |
1143 | } |
1144 | |
1145 | static int __net_init icmp_sk_init(struct net *net) |
1146 | { |
1147 | int i, err; |
1148 | |
1149 | net->ipv4.icmp_sk = |
1150 | kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); |
1151 | if (net->ipv4.icmp_sk == NULL) |
1152 | return -ENOMEM; |
1153 | |
1154 | for_each_possible_cpu(i) { |
1155 | struct sock *sk; |
1156 | |
1157 | err = inet_ctl_sock_create(&sk, PF_INET, |
1158 | SOCK_RAW, IPPROTO_ICMP, net); |
1159 | if (err < 0) |
1160 | goto fail; |
1161 | |
1162 | net->ipv4.icmp_sk[i] = sk; |
1163 | |
1164 | /* Enough space for 2 64K ICMP packets, including |
1165 | * sk_buff struct overhead. |
1166 | */ |
1167 | sk->sk_sndbuf = |
1168 | (2 * ((64 * 1024) + sizeof(struct sk_buff))); |
1169 | |
1170 | /* |
1171 | * Speedup sock_wfree() |
1172 | */ |
1173 | sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); |
1174 | inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; |
1175 | } |
1176 | |
1177 | /* Control parameters for ECHO replies. */ |
1178 | net->ipv4.sysctl_icmp_echo_ignore_all = 0; |
1179 | net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; |
1180 | |
1181 | /* Control parameter - ignore bogus broadcast responses? */ |
1182 | net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; |
1183 | |
1184 | /* |
1185 | * Configurable global rate limit. |
1186 | * |
1187 | * ratelimit defines tokens/packet consumed for dst->rate_token |
1188 | * bucket ratemask defines which icmp types are ratelimited by |
1189 | * setting it's bit position. |
1190 | * |
1191 | * default: |
1192 | * dest unreachable (3), source quench (4), |
1193 | * time exceeded (11), parameter problem (12) |
1194 | */ |
1195 | |
1196 | net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; |
1197 | net->ipv4.sysctl_icmp_ratemask = 0x1818; |
1198 | net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; |
1199 | |
1200 | return 0; |
1201 | |
1202 | fail: |
1203 | for_each_possible_cpu(i) |
1204 | inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); |
1205 | kfree(net->ipv4.icmp_sk); |
1206 | return err; |
1207 | } |
1208 | |
1209 | static struct pernet_operations __net_initdata icmp_sk_ops = { |
1210 | .init = icmp_sk_init, |
1211 | .exit = icmp_sk_exit, |
1212 | }; |
1213 | |
1214 | int __init icmp_init(void) |
1215 | { |
1216 | return register_pernet_subsys(&icmp_sk_ops); |
1217 | } |
1218 | |
1219 | EXPORT_SYMBOL(icmp_err_convert); |
1220 | EXPORT_SYMBOL(icmp_send); |
1221 | EXPORT_SYMBOL(xrlim_allow); |
1222 |
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Tags:
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od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9