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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 | EXPORT_SYMBOL(icmp_err_convert); |
185 | |
186 | /* |
187 | * ICMP control array. This specifies what to do with each ICMP. |
188 | */ |
189 | |
190 | struct icmp_control { |
191 | void (*handler)(struct sk_buff *skb); |
192 | short error; /* This ICMP is classed as an error message */ |
193 | }; |
194 | |
195 | static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1]; |
196 | |
197 | /* |
198 | * The ICMP socket(s). This is the most convenient way to flow control |
199 | * our ICMP output as well as maintain a clean interface throughout |
200 | * all layers. All Socketless IP sends will soon be gone. |
201 | * |
202 | * On SMP we have one ICMP socket per-cpu. |
203 | */ |
204 | static struct sock *icmp_sk(struct net *net) |
205 | { |
206 | return net->ipv4.icmp_sk[smp_processor_id()]; |
207 | } |
208 | |
209 | static inline struct sock *icmp_xmit_lock(struct net *net) |
210 | { |
211 | struct sock *sk; |
212 | |
213 | local_bh_disable(); |
214 | |
215 | sk = icmp_sk(net); |
216 | |
217 | if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { |
218 | /* This can happen if the output path signals a |
219 | * dst_link_failure() for an outgoing ICMP packet. |
220 | */ |
221 | local_bh_enable(); |
222 | return NULL; |
223 | } |
224 | return sk; |
225 | } |
226 | |
227 | static inline void icmp_xmit_unlock(struct sock *sk) |
228 | { |
229 | spin_unlock_bh(&sk->sk_lock.slock); |
230 | } |
231 | |
232 | /* |
233 | * Send an ICMP frame. |
234 | */ |
235 | |
236 | static inline bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt, |
237 | int type, int code) |
238 | { |
239 | struct dst_entry *dst = &rt->dst; |
240 | bool rc = true; |
241 | |
242 | if (type > NR_ICMP_TYPES) |
243 | goto out; |
244 | |
245 | /* Don't limit PMTU discovery. */ |
246 | if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) |
247 | goto out; |
248 | |
249 | /* No rate limit on loopback */ |
250 | if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) |
251 | goto out; |
252 | |
253 | /* Limit if icmp type is enabled in ratemask. */ |
254 | if ((1 << type) & net->ipv4.sysctl_icmp_ratemask) { |
255 | if (!rt->peer) |
256 | rt_bind_peer(rt, 1); |
257 | rc = inet_peer_xrlim_allow(rt->peer, |
258 | net->ipv4.sysctl_icmp_ratelimit); |
259 | } |
260 | out: |
261 | return rc; |
262 | } |
263 | |
264 | /* |
265 | * Maintain the counters used in the SNMP statistics for outgoing ICMP |
266 | */ |
267 | void icmp_out_count(struct net *net, unsigned char type) |
268 | { |
269 | ICMPMSGOUT_INC_STATS(net, type); |
270 | ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS); |
271 | } |
272 | |
273 | /* |
274 | * Checksum each fragment, and on the first include the headers and final |
275 | * checksum. |
276 | */ |
277 | static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd, |
278 | struct sk_buff *skb) |
279 | { |
280 | struct icmp_bxm *icmp_param = (struct icmp_bxm *)from; |
281 | __wsum csum; |
282 | |
283 | csum = skb_copy_and_csum_bits(icmp_param->skb, |
284 | icmp_param->offset + offset, |
285 | to, len, 0); |
286 | |
287 | skb->csum = csum_block_add(skb->csum, csum, odd); |
288 | if (icmp_pointers[icmp_param->data.icmph.type].error) |
289 | nf_ct_attach(skb, icmp_param->skb); |
290 | return 0; |
291 | } |
292 | |
293 | static void icmp_push_reply(struct icmp_bxm *icmp_param, |
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); |
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 sock *sk; |
333 | struct inet_sock *inet; |
334 | __be32 daddr; |
335 | |
336 | if (ip_options_echo(&icmp_param->replyopts, skb)) |
337 | return; |
338 | |
339 | sk = icmp_xmit_lock(net); |
340 | if (sk == NULL) |
341 | return; |
342 | inet = inet_sk(sk); |
343 | |
344 | icmp_param->data.icmph.checksum = 0; |
345 | |
346 | inet->tos = ip_hdr(skb)->tos; |
347 | daddr = ipc.addr = rt->rt_src; |
348 | ipc.opt = NULL; |
349 | ipc.tx_flags = 0; |
350 | if (icmp_param->replyopts.optlen) { |
351 | ipc.opt = &icmp_param->replyopts; |
352 | if (ipc.opt->srr) |
353 | daddr = icmp_param->replyopts.faddr; |
354 | } |
355 | { |
356 | struct flowi4 fl4 = { |
357 | .daddr = daddr, |
358 | .saddr = rt->rt_spec_dst, |
359 | .flowi4_tos = RT_TOS(ip_hdr(skb)->tos), |
360 | .flowi4_proto = IPPROTO_ICMP, |
361 | }; |
362 | security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); |
363 | rt = ip_route_output_key(net, &fl4); |
364 | if (IS_ERR(rt)) |
365 | goto out_unlock; |
366 | } |
367 | if (icmpv4_xrlim_allow(net, rt, icmp_param->data.icmph.type, |
368 | icmp_param->data.icmph.code)) |
369 | icmp_push_reply(icmp_param, &ipc, &rt); |
370 | ip_rt_put(rt); |
371 | out_unlock: |
372 | icmp_xmit_unlock(sk); |
373 | } |
374 | |
375 | static struct rtable *icmp_route_lookup(struct net *net, struct sk_buff *skb_in, |
376 | struct iphdr *iph, |
377 | __be32 saddr, u8 tos, |
378 | int type, int code, |
379 | struct icmp_bxm *param) |
380 | { |
381 | struct flowi4 fl4 = { |
382 | .daddr = (param->replyopts.srr ? |
383 | param->replyopts.faddr : iph->saddr), |
384 | .saddr = saddr, |
385 | .flowi4_tos = RT_TOS(tos), |
386 | .flowi4_proto = IPPROTO_ICMP, |
387 | .fl4_icmp_type = type, |
388 | .fl4_icmp_code = code, |
389 | }; |
390 | struct rtable *rt, *rt2; |
391 | int err; |
392 | |
393 | security_skb_classify_flow(skb_in, flowi4_to_flowi(&fl4)); |
394 | rt = __ip_route_output_key(net, &fl4); |
395 | if (IS_ERR(rt)) |
396 | return rt; |
397 | |
398 | /* No need to clone since we're just using its address. */ |
399 | rt2 = rt; |
400 | |
401 | if (!fl4.saddr) |
402 | fl4.saddr = rt->rt_src; |
403 | |
404 | rt = (struct rtable *) xfrm_lookup(net, &rt->dst, |
405 | flowi4_to_flowi(&fl4), NULL, 0); |
406 | if (!IS_ERR(rt)) { |
407 | if (rt != rt2) |
408 | return rt; |
409 | } else if (PTR_ERR(rt) == -EPERM) { |
410 | rt = NULL; |
411 | } else |
412 | return rt; |
413 | |
414 | err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4), AF_INET); |
415 | if (err) |
416 | goto relookup_failed; |
417 | |
418 | if (inet_addr_type(net, fl4.saddr) == RTN_LOCAL) { |
419 | rt2 = __ip_route_output_key(net, &fl4); |
420 | if (IS_ERR(rt2)) |
421 | err = PTR_ERR(rt2); |
422 | } else { |
423 | struct flowi4 fl4_2 = {}; |
424 | unsigned long orefdst; |
425 | |
426 | fl4_2.daddr = fl4.saddr; |
427 | rt2 = ip_route_output_key(net, &fl4_2); |
428 | if (IS_ERR(rt2)) { |
429 | err = PTR_ERR(rt2); |
430 | goto relookup_failed; |
431 | } |
432 | /* Ugh! */ |
433 | orefdst = skb_in->_skb_refdst; /* save old refdst */ |
434 | err = ip_route_input(skb_in, fl4.daddr, fl4.saddr, |
435 | RT_TOS(tos), rt2->dst.dev); |
436 | |
437 | dst_release(&rt2->dst); |
438 | rt2 = skb_rtable(skb_in); |
439 | skb_in->_skb_refdst = orefdst; /* restore old refdst */ |
440 | } |
441 | |
442 | if (err) |
443 | goto relookup_failed; |
444 | |
445 | rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst, |
446 | flowi4_to_flowi(&fl4), NULL, |
447 | XFRM_LOOKUP_ICMP); |
448 | if (!IS_ERR(rt2)) { |
449 | dst_release(&rt->dst); |
450 | rt = rt2; |
451 | } else if (PTR_ERR(rt2) == -EPERM) { |
452 | if (rt) |
453 | dst_release(&rt->dst); |
454 | return rt2; |
455 | } else { |
456 | err = PTR_ERR(rt2); |
457 | goto relookup_failed; |
458 | } |
459 | return rt; |
460 | |
461 | relookup_failed: |
462 | if (rt) |
463 | return rt; |
464 | return ERR_PTR(err); |
465 | } |
466 | |
467 | /* |
468 | * Send an ICMP message in response to a situation |
469 | * |
470 | * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. |
471 | * MAY send more (we do). |
472 | * MUST NOT change this header information. |
473 | * MUST NOT reply to a multicast/broadcast IP address. |
474 | * MUST NOT reply to a multicast/broadcast MAC address. |
475 | * MUST reply to only the first fragment. |
476 | */ |
477 | |
478 | void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) |
479 | { |
480 | struct iphdr *iph; |
481 | int room; |
482 | struct icmp_bxm icmp_param; |
483 | struct rtable *rt = skb_rtable(skb_in); |
484 | struct ipcm_cookie ipc; |
485 | __be32 saddr; |
486 | u8 tos; |
487 | struct net *net; |
488 | struct sock *sk; |
489 | |
490 | if (!rt) |
491 | goto out; |
492 | net = dev_net(rt->dst.dev); |
493 | |
494 | /* |
495 | * Find the original header. It is expected to be valid, of course. |
496 | * Check this, icmp_send is called from the most obscure devices |
497 | * sometimes. |
498 | */ |
499 | iph = ip_hdr(skb_in); |
500 | |
501 | if ((u8 *)iph < skb_in->head || |
502 | (skb_in->network_header + sizeof(*iph)) > skb_in->tail) |
503 | goto out; |
504 | |
505 | /* |
506 | * No replies to physical multicast/broadcast |
507 | */ |
508 | if (skb_in->pkt_type != PACKET_HOST) |
509 | goto out; |
510 | |
511 | /* |
512 | * Now check at the protocol level |
513 | */ |
514 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) |
515 | goto out; |
516 | |
517 | /* |
518 | * Only reply to fragment 0. We byte re-order the constant |
519 | * mask for efficiency. |
520 | */ |
521 | if (iph->frag_off & htons(IP_OFFSET)) |
522 | goto out; |
523 | |
524 | /* |
525 | * If we send an ICMP error to an ICMP error a mess would result.. |
526 | */ |
527 | if (icmp_pointers[type].error) { |
528 | /* |
529 | * We are an error, check if we are replying to an |
530 | * ICMP error |
531 | */ |
532 | if (iph->protocol == IPPROTO_ICMP) { |
533 | u8 _inner_type, *itp; |
534 | |
535 | itp = skb_header_pointer(skb_in, |
536 | skb_network_header(skb_in) + |
537 | (iph->ihl << 2) + |
538 | offsetof(struct icmphdr, |
539 | type) - |
540 | skb_in->data, |
541 | sizeof(_inner_type), |
542 | &_inner_type); |
543 | if (itp == NULL) |
544 | goto out; |
545 | |
546 | /* |
547 | * Assume any unknown ICMP type is an error. This |
548 | * isn't specified by the RFC, but think about it.. |
549 | */ |
550 | if (*itp > NR_ICMP_TYPES || |
551 | icmp_pointers[*itp].error) |
552 | goto out; |
553 | } |
554 | } |
555 | |
556 | sk = icmp_xmit_lock(net); |
557 | if (sk == NULL) |
558 | return; |
559 | |
560 | /* |
561 | * Construct source address and options. |
562 | */ |
563 | |
564 | saddr = iph->daddr; |
565 | if (!(rt->rt_flags & RTCF_LOCAL)) { |
566 | struct net_device *dev = NULL; |
567 | |
568 | rcu_read_lock(); |
569 | if (rt_is_input_route(rt) && |
570 | net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr) |
571 | dev = dev_get_by_index_rcu(net, rt->rt_iif); |
572 | |
573 | if (dev) |
574 | saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK); |
575 | else |
576 | saddr = 0; |
577 | rcu_read_unlock(); |
578 | } |
579 | |
580 | tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | |
581 | IPTOS_PREC_INTERNETCONTROL) : |
582 | iph->tos; |
583 | |
584 | if (ip_options_echo(&icmp_param.replyopts, skb_in)) |
585 | goto out_unlock; |
586 | |
587 | |
588 | /* |
589 | * Prepare data for ICMP header. |
590 | */ |
591 | |
592 | icmp_param.data.icmph.type = type; |
593 | icmp_param.data.icmph.code = code; |
594 | icmp_param.data.icmph.un.gateway = info; |
595 | icmp_param.data.icmph.checksum = 0; |
596 | icmp_param.skb = skb_in; |
597 | icmp_param.offset = skb_network_offset(skb_in); |
598 | inet_sk(sk)->tos = tos; |
599 | ipc.addr = iph->saddr; |
600 | ipc.opt = &icmp_param.replyopts; |
601 | ipc.tx_flags = 0; |
602 | |
603 | rt = icmp_route_lookup(net, skb_in, iph, saddr, tos, |
604 | type, code, &icmp_param); |
605 | if (IS_ERR(rt)) |
606 | goto out_unlock; |
607 | |
608 | if (!icmpv4_xrlim_allow(net, rt, type, code)) |
609 | goto ende; |
610 | |
611 | /* RFC says return as much as we can without exceeding 576 bytes. */ |
612 | |
613 | room = dst_mtu(&rt->dst); |
614 | if (room > 576) |
615 | room = 576; |
616 | room -= sizeof(struct iphdr) + icmp_param.replyopts.optlen; |
617 | room -= sizeof(struct icmphdr); |
618 | |
619 | icmp_param.data_len = skb_in->len - icmp_param.offset; |
620 | if (icmp_param.data_len > room) |
621 | icmp_param.data_len = room; |
622 | icmp_param.head_len = sizeof(struct icmphdr); |
623 | |
624 | icmp_push_reply(&icmp_param, &ipc, &rt); |
625 | ende: |
626 | ip_rt_put(rt); |
627 | out_unlock: |
628 | icmp_xmit_unlock(sk); |
629 | out:; |
630 | } |
631 | EXPORT_SYMBOL(icmp_send); |
632 | |
633 | |
634 | /* |
635 | * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEED, and ICMP_QUENCH. |
636 | */ |
637 | |
638 | static void icmp_unreach(struct sk_buff *skb) |
639 | { |
640 | struct iphdr *iph; |
641 | struct icmphdr *icmph; |
642 | int hash, protocol; |
643 | const struct net_protocol *ipprot; |
644 | u32 info = 0; |
645 | struct net *net; |
646 | |
647 | net = dev_net(skb_dst(skb)->dev); |
648 | |
649 | /* |
650 | * Incomplete header ? |
651 | * Only checks for the IP header, there should be an |
652 | * additional check for longer headers in upper levels. |
653 | */ |
654 | |
655 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
656 | goto out_err; |
657 | |
658 | icmph = icmp_hdr(skb); |
659 | iph = (struct iphdr *)skb->data; |
660 | |
661 | if (iph->ihl < 5) /* Mangled header, drop. */ |
662 | goto out_err; |
663 | |
664 | if (icmph->type == ICMP_DEST_UNREACH) { |
665 | switch (icmph->code & 15) { |
666 | case ICMP_NET_UNREACH: |
667 | case ICMP_HOST_UNREACH: |
668 | case ICMP_PROT_UNREACH: |
669 | case ICMP_PORT_UNREACH: |
670 | break; |
671 | case ICMP_FRAG_NEEDED: |
672 | if (ipv4_config.no_pmtu_disc) { |
673 | LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: fragmentation needed and DF set.\n", |
674 | &iph->daddr); |
675 | } else { |
676 | info = ip_rt_frag_needed(net, iph, |
677 | ntohs(icmph->un.frag.mtu), |
678 | skb->dev); |
679 | if (!info) |
680 | goto out; |
681 | } |
682 | break; |
683 | case ICMP_SR_FAILED: |
684 | LIMIT_NETDEBUG(KERN_INFO "ICMP: %pI4: Source Route Failed.\n", |
685 | &iph->daddr); |
686 | break; |
687 | default: |
688 | break; |
689 | } |
690 | if (icmph->code > NR_ICMP_UNREACH) |
691 | goto out; |
692 | } else if (icmph->type == ICMP_PARAMETERPROB) |
693 | info = ntohl(icmph->un.gateway) >> 24; |
694 | |
695 | /* |
696 | * Throw it at our lower layers |
697 | * |
698 | * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed |
699 | * header. |
700 | * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the |
701 | * transport layer. |
702 | * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to |
703 | * transport layer. |
704 | */ |
705 | |
706 | /* |
707 | * Check the other end isn't violating RFC 1122. Some routers send |
708 | * bogus responses to broadcast frames. If you see this message |
709 | * first check your netmask matches at both ends, if it does then |
710 | * get the other vendor to fix their kit. |
711 | */ |
712 | |
713 | if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses && |
714 | inet_addr_type(net, iph->daddr) == RTN_BROADCAST) { |
715 | if (net_ratelimit()) |
716 | printk(KERN_WARNING "%pI4 sent an invalid ICMP " |
717 | "type %u, code %u " |
718 | "error to a broadcast: %pI4 on %s\n", |
719 | &ip_hdr(skb)->saddr, |
720 | icmph->type, icmph->code, |
721 | &iph->daddr, |
722 | skb->dev->name); |
723 | goto out; |
724 | } |
725 | |
726 | /* Checkin full IP header plus 8 bytes of protocol to |
727 | * avoid additional coding at protocol handlers. |
728 | */ |
729 | if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) |
730 | goto out; |
731 | |
732 | iph = (struct iphdr *)skb->data; |
733 | protocol = iph->protocol; |
734 | |
735 | /* |
736 | * Deliver ICMP message to raw sockets. Pretty useless feature? |
737 | */ |
738 | raw_icmp_error(skb, protocol, info); |
739 | |
740 | hash = protocol & (MAX_INET_PROTOS - 1); |
741 | rcu_read_lock(); |
742 | ipprot = rcu_dereference(inet_protos[hash]); |
743 | if (ipprot && ipprot->err_handler) |
744 | ipprot->err_handler(skb, info); |
745 | rcu_read_unlock(); |
746 | |
747 | out: |
748 | return; |
749 | out_err: |
750 | ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); |
751 | goto out; |
752 | } |
753 | |
754 | |
755 | /* |
756 | * Handle ICMP_REDIRECT. |
757 | */ |
758 | |
759 | static void icmp_redirect(struct sk_buff *skb) |
760 | { |
761 | struct iphdr *iph; |
762 | |
763 | if (skb->len < sizeof(struct iphdr)) |
764 | goto out_err; |
765 | |
766 | /* |
767 | * Get the copied header of the packet that caused the redirect |
768 | */ |
769 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) |
770 | goto out; |
771 | |
772 | iph = (struct iphdr *)skb->data; |
773 | |
774 | switch (icmp_hdr(skb)->code & 7) { |
775 | case ICMP_REDIR_NET: |
776 | case ICMP_REDIR_NETTOS: |
777 | /* |
778 | * As per RFC recommendations now handle it as a host redirect. |
779 | */ |
780 | case ICMP_REDIR_HOST: |
781 | case ICMP_REDIR_HOSTTOS: |
782 | ip_rt_redirect(ip_hdr(skb)->saddr, iph->daddr, |
783 | icmp_hdr(skb)->un.gateway, |
784 | iph->saddr, skb->dev); |
785 | break; |
786 | } |
787 | out: |
788 | return; |
789 | out_err: |
790 | ICMP_INC_STATS_BH(dev_net(skb->dev), ICMP_MIB_INERRORS); |
791 | goto out; |
792 | } |
793 | |
794 | /* |
795 | * Handle ICMP_ECHO ("ping") requests. |
796 | * |
797 | * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo |
798 | * requests. |
799 | * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be |
800 | * included in the reply. |
801 | * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring |
802 | * echo requests, MUST have default=NOT. |
803 | * See also WRT handling of options once they are done and working. |
804 | */ |
805 | |
806 | static void icmp_echo(struct sk_buff *skb) |
807 | { |
808 | struct net *net; |
809 | |
810 | net = dev_net(skb_dst(skb)->dev); |
811 | if (!net->ipv4.sysctl_icmp_echo_ignore_all) { |
812 | struct icmp_bxm icmp_param; |
813 | |
814 | icmp_param.data.icmph = *icmp_hdr(skb); |
815 | icmp_param.data.icmph.type = ICMP_ECHOREPLY; |
816 | icmp_param.skb = skb; |
817 | icmp_param.offset = 0; |
818 | icmp_param.data_len = skb->len; |
819 | icmp_param.head_len = sizeof(struct icmphdr); |
820 | icmp_reply(&icmp_param, skb); |
821 | } |
822 | } |
823 | |
824 | /* |
825 | * Handle ICMP Timestamp requests. |
826 | * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests. |
827 | * SHOULD be in the kernel for minimum random latency. |
828 | * MUST be accurate to a few minutes. |
829 | * MUST be updated at least at 15Hz. |
830 | */ |
831 | static void icmp_timestamp(struct sk_buff *skb) |
832 | { |
833 | struct timespec tv; |
834 | struct icmp_bxm icmp_param; |
835 | /* |
836 | * Too short. |
837 | */ |
838 | if (skb->len < 4) |
839 | goto out_err; |
840 | |
841 | /* |
842 | * Fill in the current time as ms since midnight UT: |
843 | */ |
844 | getnstimeofday(&tv); |
845 | icmp_param.data.times[1] = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + |
846 | tv.tv_nsec / NSEC_PER_MSEC); |
847 | icmp_param.data.times[2] = icmp_param.data.times[1]; |
848 | if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4)) |
849 | BUG(); |
850 | icmp_param.data.icmph = *icmp_hdr(skb); |
851 | icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY; |
852 | icmp_param.data.icmph.code = 0; |
853 | icmp_param.skb = skb; |
854 | icmp_param.offset = 0; |
855 | icmp_param.data_len = 0; |
856 | icmp_param.head_len = sizeof(struct icmphdr) + 12; |
857 | icmp_reply(&icmp_param, skb); |
858 | out: |
859 | return; |
860 | out_err: |
861 | ICMP_INC_STATS_BH(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS); |
862 | goto out; |
863 | } |
864 | |
865 | |
866 | /* |
867 | * Handle ICMP_ADDRESS_MASK requests. (RFC950) |
868 | * |
869 | * RFC1122 (3.2.2.9). A host MUST only send replies to |
870 | * ADDRESS_MASK requests if it's been configured as an address mask |
871 | * agent. Receiving a request doesn't constitute implicit permission to |
872 | * act as one. Of course, implementing this correctly requires (SHOULD) |
873 | * a way to turn the functionality on and off. Another one for sysctl(), |
874 | * I guess. -- MS |
875 | * |
876 | * RFC1812 (4.3.3.9). A router MUST implement it. |
877 | * A router SHOULD have switch turning it on/off. |
878 | * This switch MUST be ON by default. |
879 | * |
880 | * Gratuitous replies, zero-source replies are not implemented, |
881 | * that complies with RFC. DO NOT implement them!!! All the idea |
882 | * of broadcast addrmask replies as specified in RFC950 is broken. |
883 | * The problem is that it is not uncommon to have several prefixes |
884 | * on one physical interface. Moreover, addrmask agent can even be |
885 | * not aware of existing another prefixes. |
886 | * If source is zero, addrmask agent cannot choose correct prefix. |
887 | * Gratuitous mask announcements suffer from the same problem. |
888 | * RFC1812 explains it, but still allows to use ADDRMASK, |
889 | * that is pretty silly. --ANK |
890 | * |
891 | * All these rules are so bizarre, that I removed kernel addrmask |
892 | * support at all. It is wrong, it is obsolete, nobody uses it in |
893 | * any case. --ANK |
894 | * |
895 | * Furthermore you can do it with a usermode address agent program |
896 | * anyway... |
897 | */ |
898 | |
899 | static void icmp_address(struct sk_buff *skb) |
900 | { |
901 | #if 0 |
902 | if (net_ratelimit()) |
903 | printk(KERN_DEBUG "a guy asks for address mask. Who is it?\n"); |
904 | #endif |
905 | } |
906 | |
907 | /* |
908 | * RFC1812 (4.3.3.9). A router SHOULD listen all replies, and complain |
909 | * loudly if an inconsistency is found. |
910 | * called with rcu_read_lock() |
911 | */ |
912 | |
913 | static void icmp_address_reply(struct sk_buff *skb) |
914 | { |
915 | struct rtable *rt = skb_rtable(skb); |
916 | struct net_device *dev = skb->dev; |
917 | struct in_device *in_dev; |
918 | struct in_ifaddr *ifa; |
919 | |
920 | if (skb->len < 4 || !(rt->rt_flags&RTCF_DIRECTSRC)) |
921 | return; |
922 | |
923 | in_dev = __in_dev_get_rcu(dev); |
924 | if (!in_dev) |
925 | return; |
926 | |
927 | if (in_dev->ifa_list && |
928 | IN_DEV_LOG_MARTIANS(in_dev) && |
929 | IN_DEV_FORWARD(in_dev)) { |
930 | __be32 _mask, *mp; |
931 | |
932 | mp = skb_header_pointer(skb, 0, sizeof(_mask), &_mask); |
933 | BUG_ON(mp == NULL); |
934 | for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) { |
935 | if (*mp == ifa->ifa_mask && |
936 | inet_ifa_match(rt->rt_src, ifa)) |
937 | break; |
938 | } |
939 | if (!ifa && net_ratelimit()) { |
940 | printk(KERN_INFO "Wrong address mask %pI4 from %s/%pI4\n", |
941 | mp, dev->name, &rt->rt_src); |
942 | } |
943 | } |
944 | } |
945 | |
946 | static void icmp_discard(struct sk_buff *skb) |
947 | { |
948 | } |
949 | |
950 | /* |
951 | * Deal with incoming ICMP packets. |
952 | */ |
953 | int icmp_rcv(struct sk_buff *skb) |
954 | { |
955 | struct icmphdr *icmph; |
956 | struct rtable *rt = skb_rtable(skb); |
957 | struct net *net = dev_net(rt->dst.dev); |
958 | |
959 | if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
960 | struct sec_path *sp = skb_sec_path(skb); |
961 | int nh; |
962 | |
963 | if (!(sp && sp->xvec[sp->len - 1]->props.flags & |
964 | XFRM_STATE_ICMP)) |
965 | goto drop; |
966 | |
967 | if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr))) |
968 | goto drop; |
969 | |
970 | nh = skb_network_offset(skb); |
971 | skb_set_network_header(skb, sizeof(*icmph)); |
972 | |
973 | if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb)) |
974 | goto drop; |
975 | |
976 | skb_set_network_header(skb, nh); |
977 | } |
978 | |
979 | ICMP_INC_STATS_BH(net, ICMP_MIB_INMSGS); |
980 | |
981 | switch (skb->ip_summed) { |
982 | case CHECKSUM_COMPLETE: |
983 | if (!csum_fold(skb->csum)) |
984 | break; |
985 | /* fall through */ |
986 | case CHECKSUM_NONE: |
987 | skb->csum = 0; |
988 | if (__skb_checksum_complete(skb)) |
989 | goto error; |
990 | } |
991 | |
992 | if (!pskb_pull(skb, sizeof(*icmph))) |
993 | goto error; |
994 | |
995 | icmph = icmp_hdr(skb); |
996 | |
997 | ICMPMSGIN_INC_STATS_BH(net, icmph->type); |
998 | /* |
999 | * 18 is the highest 'known' ICMP type. Anything else is a mystery |
1000 | * |
1001 | * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently |
1002 | * discarded. |
1003 | */ |
1004 | if (icmph->type > NR_ICMP_TYPES) |
1005 | goto error; |
1006 | |
1007 | |
1008 | /* |
1009 | * Parse the ICMP message |
1010 | */ |
1011 | |
1012 | if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) { |
1013 | /* |
1014 | * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be |
1015 | * silently ignored (we let user decide with a sysctl). |
1016 | * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently |
1017 | * discarded if to broadcast/multicast. |
1018 | */ |
1019 | if ((icmph->type == ICMP_ECHO || |
1020 | icmph->type == ICMP_TIMESTAMP) && |
1021 | net->ipv4.sysctl_icmp_echo_ignore_broadcasts) { |
1022 | goto error; |
1023 | } |
1024 | if (icmph->type != ICMP_ECHO && |
1025 | icmph->type != ICMP_TIMESTAMP && |
1026 | icmph->type != ICMP_ADDRESS && |
1027 | icmph->type != ICMP_ADDRESSREPLY) { |
1028 | goto error; |
1029 | } |
1030 | } |
1031 | |
1032 | icmp_pointers[icmph->type].handler(skb); |
1033 | |
1034 | drop: |
1035 | kfree_skb(skb); |
1036 | return 0; |
1037 | error: |
1038 | ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); |
1039 | goto drop; |
1040 | } |
1041 | |
1042 | /* |
1043 | * This table is the definition of how we handle ICMP. |
1044 | */ |
1045 | static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = { |
1046 | [ICMP_ECHOREPLY] = { |
1047 | .handler = icmp_discard, |
1048 | }, |
1049 | [1] = { |
1050 | .handler = icmp_discard, |
1051 | .error = 1, |
1052 | }, |
1053 | [2] = { |
1054 | .handler = icmp_discard, |
1055 | .error = 1, |
1056 | }, |
1057 | [ICMP_DEST_UNREACH] = { |
1058 | .handler = icmp_unreach, |
1059 | .error = 1, |
1060 | }, |
1061 | [ICMP_SOURCE_QUENCH] = { |
1062 | .handler = icmp_unreach, |
1063 | .error = 1, |
1064 | }, |
1065 | [ICMP_REDIRECT] = { |
1066 | .handler = icmp_redirect, |
1067 | .error = 1, |
1068 | }, |
1069 | [6] = { |
1070 | .handler = icmp_discard, |
1071 | .error = 1, |
1072 | }, |
1073 | [7] = { |
1074 | .handler = icmp_discard, |
1075 | .error = 1, |
1076 | }, |
1077 | [ICMP_ECHO] = { |
1078 | .handler = icmp_echo, |
1079 | }, |
1080 | [9] = { |
1081 | .handler = icmp_discard, |
1082 | .error = 1, |
1083 | }, |
1084 | [10] = { |
1085 | .handler = icmp_discard, |
1086 | .error = 1, |
1087 | }, |
1088 | [ICMP_TIME_EXCEEDED] = { |
1089 | .handler = icmp_unreach, |
1090 | .error = 1, |
1091 | }, |
1092 | [ICMP_PARAMETERPROB] = { |
1093 | .handler = icmp_unreach, |
1094 | .error = 1, |
1095 | }, |
1096 | [ICMP_TIMESTAMP] = { |
1097 | .handler = icmp_timestamp, |
1098 | }, |
1099 | [ICMP_TIMESTAMPREPLY] = { |
1100 | .handler = icmp_discard, |
1101 | }, |
1102 | [ICMP_INFO_REQUEST] = { |
1103 | .handler = icmp_discard, |
1104 | }, |
1105 | [ICMP_INFO_REPLY] = { |
1106 | .handler = icmp_discard, |
1107 | }, |
1108 | [ICMP_ADDRESS] = { |
1109 | .handler = icmp_address, |
1110 | }, |
1111 | [ICMP_ADDRESSREPLY] = { |
1112 | .handler = icmp_address_reply, |
1113 | }, |
1114 | }; |
1115 | |
1116 | static void __net_exit icmp_sk_exit(struct net *net) |
1117 | { |
1118 | int i; |
1119 | |
1120 | for_each_possible_cpu(i) |
1121 | inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); |
1122 | kfree(net->ipv4.icmp_sk); |
1123 | net->ipv4.icmp_sk = NULL; |
1124 | } |
1125 | |
1126 | static int __net_init icmp_sk_init(struct net *net) |
1127 | { |
1128 | int i, err; |
1129 | |
1130 | net->ipv4.icmp_sk = |
1131 | kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL); |
1132 | if (net->ipv4.icmp_sk == NULL) |
1133 | return -ENOMEM; |
1134 | |
1135 | for_each_possible_cpu(i) { |
1136 | struct sock *sk; |
1137 | |
1138 | err = inet_ctl_sock_create(&sk, PF_INET, |
1139 | SOCK_RAW, IPPROTO_ICMP, net); |
1140 | if (err < 0) |
1141 | goto fail; |
1142 | |
1143 | net->ipv4.icmp_sk[i] = sk; |
1144 | |
1145 | /* Enough space for 2 64K ICMP packets, including |
1146 | * sk_buff struct overhead. |
1147 | */ |
1148 | sk->sk_sndbuf = |
1149 | (2 * ((64 * 1024) + sizeof(struct sk_buff))); |
1150 | |
1151 | /* |
1152 | * Speedup sock_wfree() |
1153 | */ |
1154 | sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); |
1155 | inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT; |
1156 | } |
1157 | |
1158 | /* Control parameters for ECHO replies. */ |
1159 | net->ipv4.sysctl_icmp_echo_ignore_all = 0; |
1160 | net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1; |
1161 | |
1162 | /* Control parameter - ignore bogus broadcast responses? */ |
1163 | net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1; |
1164 | |
1165 | /* |
1166 | * Configurable global rate limit. |
1167 | * |
1168 | * ratelimit defines tokens/packet consumed for dst->rate_token |
1169 | * bucket ratemask defines which icmp types are ratelimited by |
1170 | * setting it's bit position. |
1171 | * |
1172 | * default: |
1173 | * dest unreachable (3), source quench (4), |
1174 | * time exceeded (11), parameter problem (12) |
1175 | */ |
1176 | |
1177 | net->ipv4.sysctl_icmp_ratelimit = 1 * HZ; |
1178 | net->ipv4.sysctl_icmp_ratemask = 0x1818; |
1179 | net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0; |
1180 | |
1181 | return 0; |
1182 | |
1183 | fail: |
1184 | for_each_possible_cpu(i) |
1185 | inet_ctl_sock_destroy(net->ipv4.icmp_sk[i]); |
1186 | kfree(net->ipv4.icmp_sk); |
1187 | return err; |
1188 | } |
1189 | |
1190 | static struct pernet_operations __net_initdata icmp_sk_ops = { |
1191 | .init = icmp_sk_init, |
1192 | .exit = icmp_sk_exit, |
1193 | }; |
1194 | |
1195 | int __init icmp_init(void) |
1196 | { |
1197 | return register_pernet_subsys(&icmp_sk_ops); |
1198 | } |
1199 |
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