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 #include <net/l3mdev.h>
100
101 /*
102 * Build xmit assembly blocks
103 */
104
105 struct icmp_bxm {
106 struct sk_buff *skb;
107 int offset;
108 int data_len;
109
110 struct {
111 struct icmphdr icmph;
112 __be32 times[3];
113 } data;
114 int head_len;
115 struct ip_options_data replyopts;
116 };
117
118 /* An array of errno for error messages from dest unreach. */
119 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
120
121 const struct icmp_err icmp_err_convert[] = {
122 {
123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
124 .fatal = 0,
125 },
126 {
127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
128 .fatal = 0,
129 },
130 {
131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
132 .fatal = 1,
133 },
134 {
135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
136 .fatal = 1,
137 },
138 {
139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
140 .fatal = 0,
141 },
142 {
143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
144 .fatal = 0,
145 },
146 {
147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
148 .fatal = 1,
149 },
150 {
151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
152 .fatal = 1,
153 },
154 {
155 .errno = ENONET, /* ICMP_HOST_ISOLATED */
156 .fatal = 1,
157 },
158 {
159 .errno = ENETUNREACH, /* ICMP_NET_ANO */
160 .fatal = 1,
161 },
162 {
163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
164 .fatal = 1,
165 },
166 {
167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
168 .fatal = 0,
169 },
170 {
171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
172 .fatal = 0,
173 },
174 {
175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
176 .fatal = 1,
177 },
178 {
179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
180 .fatal = 1,
181 },
182 {
183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
184 .fatal = 1,
185 },
186 };
187 EXPORT_SYMBOL(icmp_err_convert);
188
189 /*
190 * ICMP control array. This specifies what to do with each ICMP.
191 */
192
193 struct icmp_control {
194 bool (*handler)(struct sk_buff *skb);
195 short error; /* This ICMP is classed as an error message */
196 };
197
198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
199
200 /*
201 * The ICMP socket(s). This is the most convenient way to flow control
202 * our ICMP output as well as maintain a clean interface throughout
203 * all layers. All Socketless IP sends will soon be gone.
204 *
205 * On SMP we have one ICMP socket per-cpu.
206 */
icmp_sk(struct net * net)207 static struct sock *icmp_sk(struct net *net)
208 {
209 return *this_cpu_ptr(net->ipv4.icmp_sk);
210 }
211
icmp_xmit_lock(struct net * net)212 static inline struct sock *icmp_xmit_lock(struct net *net)
213 {
214 struct sock *sk;
215
216 local_bh_disable();
217
218 sk = icmp_sk(net);
219
220 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
221 /* This can happen if the output path signals a
222 * dst_link_failure() for an outgoing ICMP packet.
223 */
224 local_bh_enable();
225 return NULL;
226 }
227 return sk;
228 }
229
icmp_xmit_unlock(struct sock * sk)230 static inline void icmp_xmit_unlock(struct sock *sk)
231 {
232 spin_unlock_bh(&sk->sk_lock.slock);
233 }
234
235 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
236 int sysctl_icmp_msgs_burst __read_mostly = 50;
237
238 static struct {
239 spinlock_t lock;
240 u32 credit;
241 u32 stamp;
242 } icmp_global = {
243 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
244 };
245
246 /**
247 * icmp_global_allow - Are we allowed to send one more ICMP message ?
248 *
249 * Uses a token bucket to limit our ICMP messages to sysctl_icmp_msgs_per_sec.
250 * Returns false if we reached the limit and can not send another packet.
251 * Note: called with BH disabled
252 */
icmp_global_allow(void)253 bool icmp_global_allow(void)
254 {
255 u32 credit, delta, incr = 0, now = (u32)jiffies;
256 bool rc = false;
257
258 /* Check if token bucket is empty and cannot be refilled
259 * without taking the spinlock.
260 */
261 if (!icmp_global.credit) {
262 delta = min_t(u32, now - icmp_global.stamp, HZ);
263 if (delta < HZ / 50)
264 return false;
265 }
266
267 spin_lock(&icmp_global.lock);
268 delta = min_t(u32, now - icmp_global.stamp, HZ);
269 if (delta >= HZ / 50) {
270 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
271 if (incr)
272 icmp_global.stamp = now;
273 }
274 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
275 if (credit) {
276 credit--;
277 rc = true;
278 }
279 icmp_global.credit = credit;
280 spin_unlock(&icmp_global.lock);
281 return rc;
282 }
283 EXPORT_SYMBOL(icmp_global_allow);
284
285 /*
286 * Send an ICMP frame.
287 */
288
icmpv4_xrlim_allow(struct net * net,struct rtable * rt,struct flowi4 * fl4,int type,int code)289 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
290 struct flowi4 *fl4, int type, int code)
291 {
292 struct dst_entry *dst = &rt->dst;
293 bool rc = true;
294
295 if (type > NR_ICMP_TYPES)
296 goto out;
297
298 /* Don't limit PMTU discovery. */
299 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
300 goto out;
301
302 /* No rate limit on loopback */
303 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
304 goto out;
305
306 /* Limit if icmp type is enabled in ratemask. */
307 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
308 goto out;
309
310 rc = false;
311 if (icmp_global_allow()) {
312 int vif = l3mdev_master_ifindex(dst->dev);
313 struct inet_peer *peer;
314
315 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
316 rc = inet_peer_xrlim_allow(peer,
317 net->ipv4.sysctl_icmp_ratelimit);
318 if (peer)
319 inet_putpeer(peer);
320 }
321 out:
322 return rc;
323 }
324
325 /*
326 * Maintain the counters used in the SNMP statistics for outgoing ICMP
327 */
icmp_out_count(struct net * net,unsigned char type)328 void icmp_out_count(struct net *net, unsigned char type)
329 {
330 ICMPMSGOUT_INC_STATS(net, type);
331 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
332 }
333
334 /*
335 * Checksum each fragment, and on the first include the headers and final
336 * checksum.
337 */
icmp_glue_bits(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)338 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
339 struct sk_buff *skb)
340 {
341 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
342 __wsum csum;
343
344 csum = skb_copy_and_csum_bits(icmp_param->skb,
345 icmp_param->offset + offset,
346 to, len, 0);
347
348 skb->csum = csum_block_add(skb->csum, csum, odd);
349 if (icmp_pointers[icmp_param->data.icmph.type].error)
350 nf_ct_attach(skb, icmp_param->skb);
351 return 0;
352 }
353
icmp_push_reply(struct icmp_bxm * icmp_param,struct flowi4 * fl4,struct ipcm_cookie * ipc,struct rtable ** rt)354 static void icmp_push_reply(struct icmp_bxm *icmp_param,
355 struct flowi4 *fl4,
356 struct ipcm_cookie *ipc, struct rtable **rt)
357 {
358 struct sock *sk;
359 struct sk_buff *skb;
360
361 sk = icmp_sk(dev_net((*rt)->dst.dev));
362 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
363 icmp_param->data_len+icmp_param->head_len,
364 icmp_param->head_len,
365 ipc, rt, MSG_DONTWAIT) < 0) {
366 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
367 ip_flush_pending_frames(sk);
368 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
369 struct icmphdr *icmph = icmp_hdr(skb);
370 __wsum csum = 0;
371 struct sk_buff *skb1;
372
373 skb_queue_walk(&sk->sk_write_queue, skb1) {
374 csum = csum_add(csum, skb1->csum);
375 }
376 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
377 (char *)icmph,
378 icmp_param->head_len, csum);
379 icmph->checksum = csum_fold(csum);
380 skb->ip_summed = CHECKSUM_NONE;
381 ip_push_pending_frames(sk, fl4);
382 }
383 }
384
385 /*
386 * Driving logic for building and sending ICMP messages.
387 */
388
icmp_reply(struct icmp_bxm * icmp_param,struct sk_buff * skb)389 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
390 {
391 struct ipcm_cookie ipc;
392 struct rtable *rt = skb_rtable(skb);
393 struct net *net = dev_net(rt->dst.dev);
394 struct flowi4 fl4;
395 struct sock *sk;
396 struct inet_sock *inet;
397 __be32 daddr, saddr;
398 u32 mark = IP4_REPLY_MARK(net, skb->mark);
399
400 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
401 return;
402
403 sk = icmp_xmit_lock(net);
404 if (!sk)
405 return;
406 inet = inet_sk(sk);
407
408 icmp_param->data.icmph.checksum = 0;
409
410 inet->tos = ip_hdr(skb)->tos;
411 sk->sk_mark = mark;
412 daddr = ipc.addr = ip_hdr(skb)->saddr;
413 saddr = fib_compute_spec_dst(skb);
414 ipc.opt = NULL;
415 ipc.tx_flags = 0;
416 ipc.ttl = 0;
417 ipc.tos = -1;
418
419 if (icmp_param->replyopts.opt.opt.optlen) {
420 ipc.opt = &icmp_param->replyopts.opt;
421 if (ipc.opt->opt.srr)
422 daddr = icmp_param->replyopts.opt.opt.faddr;
423 }
424 memset(&fl4, 0, sizeof(fl4));
425 fl4.daddr = daddr;
426 fl4.saddr = saddr;
427 fl4.flowi4_mark = mark;
428 fl4.flowi4_uid = sock_net_uid(net, NULL);
429 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
430 fl4.flowi4_proto = IPPROTO_ICMP;
431 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
432 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
433 rt = ip_route_output_key(net, &fl4);
434 if (IS_ERR(rt))
435 goto out_unlock;
436 if (icmpv4_xrlim_allow(net, rt, &fl4, icmp_param->data.icmph.type,
437 icmp_param->data.icmph.code))
438 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
439 ip_rt_put(rt);
440 out_unlock:
441 icmp_xmit_unlock(sk);
442 }
443
444 #ifdef CONFIG_IP_ROUTE_MULTIPATH
445
446 /* Source and destination is swapped. See ip_multipath_icmp_hash */
icmp_multipath_hash_skb(const struct sk_buff * skb)447 static int icmp_multipath_hash_skb(const struct sk_buff *skb)
448 {
449 const struct iphdr *iph = ip_hdr(skb);
450
451 return fib_multipath_hash(iph->daddr, iph->saddr);
452 }
453
454 #else
455
456 #define icmp_multipath_hash_skb(skb) (-1)
457
458 #endif
459
icmp_route_lookup(struct net * net,struct flowi4 * fl4,struct sk_buff * skb_in,const struct iphdr * iph,__be32 saddr,u8 tos,u32 mark,int type,int code,struct icmp_bxm * param)460 static struct rtable *icmp_route_lookup(struct net *net,
461 struct flowi4 *fl4,
462 struct sk_buff *skb_in,
463 const struct iphdr *iph,
464 __be32 saddr, u8 tos, u32 mark,
465 int type, int code,
466 struct icmp_bxm *param)
467 {
468 struct rtable *rt, *rt2;
469 struct flowi4 fl4_dec;
470 int err;
471
472 memset(fl4, 0, sizeof(*fl4));
473 fl4->daddr = (param->replyopts.opt.opt.srr ?
474 param->replyopts.opt.opt.faddr : iph->saddr);
475 fl4->saddr = saddr;
476 fl4->flowi4_mark = mark;
477 fl4->flowi4_uid = sock_net_uid(net, NULL);
478 fl4->flowi4_tos = RT_TOS(tos);
479 fl4->flowi4_proto = IPPROTO_ICMP;
480 fl4->fl4_icmp_type = type;
481 fl4->fl4_icmp_code = code;
482 fl4->flowi4_oif = l3mdev_master_ifindex(skb_dst(skb_in)->dev);
483
484 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
485 rt = __ip_route_output_key_hash(net, fl4,
486 icmp_multipath_hash_skb(skb_in));
487 if (IS_ERR(rt))
488 return rt;
489
490 /* No need to clone since we're just using its address. */
491 rt2 = rt;
492
493 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
494 flowi4_to_flowi(fl4), NULL, 0);
495 if (!IS_ERR(rt)) {
496 if (rt != rt2)
497 return rt;
498 } else if (PTR_ERR(rt) == -EPERM) {
499 rt = NULL;
500 } else
501 return rt;
502
503 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
504 if (err)
505 goto relookup_failed;
506
507 if (inet_addr_type_dev_table(net, skb_dst(skb_in)->dev,
508 fl4_dec.saddr) == RTN_LOCAL) {
509 rt2 = __ip_route_output_key(net, &fl4_dec);
510 if (IS_ERR(rt2))
511 err = PTR_ERR(rt2);
512 } else {
513 struct flowi4 fl4_2 = {};
514 unsigned long orefdst;
515
516 fl4_2.daddr = fl4_dec.saddr;
517 rt2 = ip_route_output_key(net, &fl4_2);
518 if (IS_ERR(rt2)) {
519 err = PTR_ERR(rt2);
520 goto relookup_failed;
521 }
522 /* Ugh! */
523 orefdst = skb_in->_skb_refdst; /* save old refdst */
524 skb_dst_set(skb_in, NULL);
525 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
526 RT_TOS(tos), rt2->dst.dev);
527
528 dst_release(&rt2->dst);
529 rt2 = skb_rtable(skb_in);
530 skb_in->_skb_refdst = orefdst; /* restore old refdst */
531 }
532
533 if (err)
534 goto relookup_failed;
535
536 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
537 flowi4_to_flowi(&fl4_dec), NULL,
538 XFRM_LOOKUP_ICMP);
539 if (!IS_ERR(rt2)) {
540 dst_release(&rt->dst);
541 memcpy(fl4, &fl4_dec, sizeof(*fl4));
542 rt = rt2;
543 } else if (PTR_ERR(rt2) == -EPERM) {
544 if (rt)
545 dst_release(&rt->dst);
546 return rt2;
547 } else {
548 err = PTR_ERR(rt2);
549 goto relookup_failed;
550 }
551 return rt;
552
553 relookup_failed:
554 if (rt)
555 return rt;
556 return ERR_PTR(err);
557 }
558
559 /*
560 * Send an ICMP message in response to a situation
561 *
562 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
563 * MAY send more (we do).
564 * MUST NOT change this header information.
565 * MUST NOT reply to a multicast/broadcast IP address.
566 * MUST NOT reply to a multicast/broadcast MAC address.
567 * MUST reply to only the first fragment.
568 */
569
icmp_send(struct sk_buff * skb_in,int type,int code,__be32 info)570 void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
571 {
572 struct iphdr *iph;
573 int room;
574 struct icmp_bxm *icmp_param;
575 struct rtable *rt = skb_rtable(skb_in);
576 struct ipcm_cookie ipc;
577 struct flowi4 fl4;
578 __be32 saddr;
579 u8 tos;
580 u32 mark;
581 struct net *net;
582 struct sock *sk;
583
584 if (!rt)
585 goto out;
586 net = dev_net(rt->dst.dev);
587
588 /*
589 * Find the original header. It is expected to be valid, of course.
590 * Check this, icmp_send is called from the most obscure devices
591 * sometimes.
592 */
593 iph = ip_hdr(skb_in);
594
595 if ((u8 *)iph < skb_in->head ||
596 (skb_network_header(skb_in) + sizeof(*iph)) >
597 skb_tail_pointer(skb_in))
598 goto out;
599
600 /*
601 * No replies to physical multicast/broadcast
602 */
603 if (skb_in->pkt_type != PACKET_HOST)
604 goto out;
605
606 /*
607 * Now check at the protocol level
608 */
609 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
610 goto out;
611
612 /*
613 * Only reply to fragment 0. We byte re-order the constant
614 * mask for efficiency.
615 */
616 if (iph->frag_off & htons(IP_OFFSET))
617 goto out;
618
619 /*
620 * If we send an ICMP error to an ICMP error a mess would result..
621 */
622 if (icmp_pointers[type].error) {
623 /*
624 * We are an error, check if we are replying to an
625 * ICMP error
626 */
627 if (iph->protocol == IPPROTO_ICMP) {
628 u8 _inner_type, *itp;
629
630 itp = skb_header_pointer(skb_in,
631 skb_network_header(skb_in) +
632 (iph->ihl << 2) +
633 offsetof(struct icmphdr,
634 type) -
635 skb_in->data,
636 sizeof(_inner_type),
637 &_inner_type);
638 if (!itp)
639 goto out;
640
641 /*
642 * Assume any unknown ICMP type is an error. This
643 * isn't specified by the RFC, but think about it..
644 */
645 if (*itp > NR_ICMP_TYPES ||
646 icmp_pointers[*itp].error)
647 goto out;
648 }
649 }
650
651 icmp_param = kmalloc(sizeof(*icmp_param), GFP_ATOMIC);
652 if (!icmp_param)
653 return;
654
655 sk = icmp_xmit_lock(net);
656 if (!sk)
657 goto out_free;
658
659 /*
660 * Construct source address and options.
661 */
662
663 saddr = iph->daddr;
664 if (!(rt->rt_flags & RTCF_LOCAL)) {
665 struct net_device *dev = NULL;
666
667 rcu_read_lock();
668 if (rt_is_input_route(rt) &&
669 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
670 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
671
672 if (dev)
673 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
674 else
675 saddr = 0;
676 rcu_read_unlock();
677 }
678
679 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
680 IPTOS_PREC_INTERNETCONTROL) :
681 iph->tos;
682 mark = IP4_REPLY_MARK(net, skb_in->mark);
683
684 if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in))
685 goto out_unlock;
686
687
688 /*
689 * Prepare data for ICMP header.
690 */
691
692 icmp_param->data.icmph.type = type;
693 icmp_param->data.icmph.code = code;
694 icmp_param->data.icmph.un.gateway = info;
695 icmp_param->data.icmph.checksum = 0;
696 icmp_param->skb = skb_in;
697 icmp_param->offset = skb_network_offset(skb_in);
698 inet_sk(sk)->tos = tos;
699 sk->sk_mark = mark;
700 ipc.addr = iph->saddr;
701 ipc.opt = &icmp_param->replyopts.opt;
702 ipc.tx_flags = 0;
703 ipc.ttl = 0;
704 ipc.tos = -1;
705
706 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
707 type, code, icmp_param);
708 if (IS_ERR(rt))
709 goto out_unlock;
710
711 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
712 goto ende;
713
714 /* RFC says return as much as we can without exceeding 576 bytes. */
715
716 room = dst_mtu(&rt->dst);
717 if (room > 576)
718 room = 576;
719 room -= sizeof(struct iphdr) + icmp_param->replyopts.opt.opt.optlen;
720 room -= sizeof(struct icmphdr);
721
722 icmp_param->data_len = skb_in->len - icmp_param->offset;
723 if (icmp_param->data_len > room)
724 icmp_param->data_len = room;
725 icmp_param->head_len = sizeof(struct icmphdr);
726
727 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
728 ende:
729 ip_rt_put(rt);
730 out_unlock:
731 icmp_xmit_unlock(sk);
732 out_free:
733 kfree(icmp_param);
734 out:;
735 }
736 EXPORT_SYMBOL(icmp_send);
737
738
icmp_socket_deliver(struct sk_buff * skb,u32 info)739 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
740 {
741 const struct iphdr *iph = (const struct iphdr *) skb->data;
742 const struct net_protocol *ipprot;
743 int protocol = iph->protocol;
744
745 /* Checkin full IP header plus 8 bytes of protocol to
746 * avoid additional coding at protocol handlers.
747 */
748 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
749 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
750 return;
751 }
752
753 raw_icmp_error(skb, protocol, info);
754
755 ipprot = rcu_dereference(inet_protos[protocol]);
756 if (ipprot && ipprot->err_handler)
757 ipprot->err_handler(skb, info);
758 }
759
icmp_tag_validation(int proto)760 static bool icmp_tag_validation(int proto)
761 {
762 bool ok;
763
764 rcu_read_lock();
765 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
766 rcu_read_unlock();
767 return ok;
768 }
769
770 /*
771 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
772 * ICMP_PARAMETERPROB.
773 */
774
icmp_unreach(struct sk_buff * skb)775 static bool icmp_unreach(struct sk_buff *skb)
776 {
777 const struct iphdr *iph;
778 struct icmphdr *icmph;
779 struct net *net;
780 u32 info = 0;
781
782 net = dev_net(skb_dst(skb)->dev);
783
784 /*
785 * Incomplete header ?
786 * Only checks for the IP header, there should be an
787 * additional check for longer headers in upper levels.
788 */
789
790 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
791 goto out_err;
792
793 icmph = icmp_hdr(skb);
794 iph = (const struct iphdr *)skb->data;
795
796 if (iph->ihl < 5) /* Mangled header, drop. */
797 goto out_err;
798
799 switch (icmph->type) {
800 case ICMP_DEST_UNREACH:
801 switch (icmph->code & 15) {
802 case ICMP_NET_UNREACH:
803 case ICMP_HOST_UNREACH:
804 case ICMP_PROT_UNREACH:
805 case ICMP_PORT_UNREACH:
806 break;
807 case ICMP_FRAG_NEEDED:
808 /* for documentation of the ip_no_pmtu_disc
809 * values please see
810 * Documentation/networking/ip-sysctl.txt
811 */
812 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
813 default:
814 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
815 &iph->daddr);
816 break;
817 case 2:
818 goto out;
819 case 3:
820 if (!icmp_tag_validation(iph->protocol))
821 goto out;
822 /* fall through */
823 case 0:
824 info = ntohs(icmph->un.frag.mtu);
825 }
826 break;
827 case ICMP_SR_FAILED:
828 net_dbg_ratelimited("%pI4: Source Route Failed\n",
829 &iph->daddr);
830 break;
831 default:
832 break;
833 }
834 if (icmph->code > NR_ICMP_UNREACH)
835 goto out;
836 break;
837 case ICMP_PARAMETERPROB:
838 info = ntohl(icmph->un.gateway) >> 24;
839 break;
840 case ICMP_TIME_EXCEEDED:
841 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
842 if (icmph->code == ICMP_EXC_FRAGTIME)
843 goto out;
844 break;
845 }
846
847 /*
848 * Throw it at our lower layers
849 *
850 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
851 * header.
852 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
853 * transport layer.
854 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
855 * transport layer.
856 */
857
858 /*
859 * Check the other end isn't violating RFC 1122. Some routers send
860 * bogus responses to broadcast frames. If you see this message
861 * first check your netmask matches at both ends, if it does then
862 * get the other vendor to fix their kit.
863 */
864
865 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
866 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
867 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
868 &ip_hdr(skb)->saddr,
869 icmph->type, icmph->code,
870 &iph->daddr, skb->dev->name);
871 goto out;
872 }
873
874 icmp_socket_deliver(skb, info);
875
876 out:
877 return true;
878 out_err:
879 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
880 return false;
881 }
882
883
884 /*
885 * Handle ICMP_REDIRECT.
886 */
887
icmp_redirect(struct sk_buff * skb)888 static bool icmp_redirect(struct sk_buff *skb)
889 {
890 if (skb->len < sizeof(struct iphdr)) {
891 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
892 return false;
893 }
894
895 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
896 /* there aught to be a stat */
897 return false;
898 }
899
900 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
901 return true;
902 }
903
904 /*
905 * Handle ICMP_ECHO ("ping") requests.
906 *
907 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
908 * requests.
909 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
910 * included in the reply.
911 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
912 * echo requests, MUST have default=NOT.
913 * See also WRT handling of options once they are done and working.
914 */
915
icmp_echo(struct sk_buff * skb)916 static bool icmp_echo(struct sk_buff *skb)
917 {
918 struct net *net;
919
920 net = dev_net(skb_dst(skb)->dev);
921 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
922 struct icmp_bxm icmp_param;
923
924 icmp_param.data.icmph = *icmp_hdr(skb);
925 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
926 icmp_param.skb = skb;
927 icmp_param.offset = 0;
928 icmp_param.data_len = skb->len;
929 icmp_param.head_len = sizeof(struct icmphdr);
930 icmp_reply(&icmp_param, skb);
931 }
932 /* should there be an ICMP stat for ignored echos? */
933 return true;
934 }
935
936 /*
937 * Handle ICMP Timestamp requests.
938 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
939 * SHOULD be in the kernel for minimum random latency.
940 * MUST be accurate to a few minutes.
941 * MUST be updated at least at 15Hz.
942 */
icmp_timestamp(struct sk_buff * skb)943 static bool icmp_timestamp(struct sk_buff *skb)
944 {
945 struct icmp_bxm icmp_param;
946 /*
947 * Too short.
948 */
949 if (skb->len < 4)
950 goto out_err;
951
952 /*
953 * Fill in the current time as ms since midnight UT:
954 */
955 icmp_param.data.times[1] = inet_current_timestamp();
956 icmp_param.data.times[2] = icmp_param.data.times[1];
957 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
958 BUG();
959 icmp_param.data.icmph = *icmp_hdr(skb);
960 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
961 icmp_param.data.icmph.code = 0;
962 icmp_param.skb = skb;
963 icmp_param.offset = 0;
964 icmp_param.data_len = 0;
965 icmp_param.head_len = sizeof(struct icmphdr) + 12;
966 icmp_reply(&icmp_param, skb);
967 return true;
968
969 out_err:
970 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
971 return false;
972 }
973
icmp_discard(struct sk_buff * skb)974 static bool icmp_discard(struct sk_buff *skb)
975 {
976 /* pretend it was a success */
977 return true;
978 }
979
980 /*
981 * Deal with incoming ICMP packets.
982 */
icmp_rcv(struct sk_buff * skb)983 int icmp_rcv(struct sk_buff *skb)
984 {
985 struct icmphdr *icmph;
986 struct rtable *rt = skb_rtable(skb);
987 struct net *net = dev_net(rt->dst.dev);
988 bool success;
989
990 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
991 struct sec_path *sp = skb_sec_path(skb);
992 int nh;
993
994 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
995 XFRM_STATE_ICMP))
996 goto drop;
997
998 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
999 goto drop;
1000
1001 nh = skb_network_offset(skb);
1002 skb_set_network_header(skb, sizeof(*icmph));
1003
1004 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1005 goto drop;
1006
1007 skb_set_network_header(skb, nh);
1008 }
1009
1010 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1011
1012 if (skb_checksum_simple_validate(skb))
1013 goto csum_error;
1014
1015 if (!pskb_pull(skb, sizeof(*icmph)))
1016 goto error;
1017
1018 icmph = icmp_hdr(skb);
1019
1020 ICMPMSGIN_INC_STATS(net, icmph->type);
1021 /*
1022 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1023 *
1024 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1025 * discarded.
1026 */
1027 if (icmph->type > NR_ICMP_TYPES)
1028 goto error;
1029
1030
1031 /*
1032 * Parse the ICMP message
1033 */
1034
1035 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1036 /*
1037 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1038 * silently ignored (we let user decide with a sysctl).
1039 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1040 * discarded if to broadcast/multicast.
1041 */
1042 if ((icmph->type == ICMP_ECHO ||
1043 icmph->type == ICMP_TIMESTAMP) &&
1044 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1045 goto error;
1046 }
1047 if (icmph->type != ICMP_ECHO &&
1048 icmph->type != ICMP_TIMESTAMP &&
1049 icmph->type != ICMP_ADDRESS &&
1050 icmph->type != ICMP_ADDRESSREPLY) {
1051 goto error;
1052 }
1053 }
1054
1055 success = icmp_pointers[icmph->type].handler(skb);
1056
1057 if (success) {
1058 consume_skb(skb);
1059 return 0;
1060 }
1061
1062 drop:
1063 kfree_skb(skb);
1064 return 0;
1065 csum_error:
1066 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1067 error:
1068 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1069 goto drop;
1070 }
1071
icmp_err(struct sk_buff * skb,u32 info)1072 void icmp_err(struct sk_buff *skb, u32 info)
1073 {
1074 struct iphdr *iph = (struct iphdr *)skb->data;
1075 int offset = iph->ihl<<2;
1076 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1077 int type = icmp_hdr(skb)->type;
1078 int code = icmp_hdr(skb)->code;
1079 struct net *net = dev_net(skb->dev);
1080
1081 /*
1082 * Use ping_err to handle all icmp errors except those
1083 * triggered by ICMP_ECHOREPLY which sent from kernel.
1084 */
1085 if (icmph->type != ICMP_ECHOREPLY) {
1086 ping_err(skb, offset, info);
1087 return;
1088 }
1089
1090 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1091 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1092 else if (type == ICMP_REDIRECT)
1093 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1094 }
1095
1096 /*
1097 * This table is the definition of how we handle ICMP.
1098 */
1099 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1100 [ICMP_ECHOREPLY] = {
1101 .handler = ping_rcv,
1102 },
1103 [1] = {
1104 .handler = icmp_discard,
1105 .error = 1,
1106 },
1107 [2] = {
1108 .handler = icmp_discard,
1109 .error = 1,
1110 },
1111 [ICMP_DEST_UNREACH] = {
1112 .handler = icmp_unreach,
1113 .error = 1,
1114 },
1115 [ICMP_SOURCE_QUENCH] = {
1116 .handler = icmp_unreach,
1117 .error = 1,
1118 },
1119 [ICMP_REDIRECT] = {
1120 .handler = icmp_redirect,
1121 .error = 1,
1122 },
1123 [6] = {
1124 .handler = icmp_discard,
1125 .error = 1,
1126 },
1127 [7] = {
1128 .handler = icmp_discard,
1129 .error = 1,
1130 },
1131 [ICMP_ECHO] = {
1132 .handler = icmp_echo,
1133 },
1134 [9] = {
1135 .handler = icmp_discard,
1136 .error = 1,
1137 },
1138 [10] = {
1139 .handler = icmp_discard,
1140 .error = 1,
1141 },
1142 [ICMP_TIME_EXCEEDED] = {
1143 .handler = icmp_unreach,
1144 .error = 1,
1145 },
1146 [ICMP_PARAMETERPROB] = {
1147 .handler = icmp_unreach,
1148 .error = 1,
1149 },
1150 [ICMP_TIMESTAMP] = {
1151 .handler = icmp_timestamp,
1152 },
1153 [ICMP_TIMESTAMPREPLY] = {
1154 .handler = icmp_discard,
1155 },
1156 [ICMP_INFO_REQUEST] = {
1157 .handler = icmp_discard,
1158 },
1159 [ICMP_INFO_REPLY] = {
1160 .handler = icmp_discard,
1161 },
1162 [ICMP_ADDRESS] = {
1163 .handler = icmp_discard,
1164 },
1165 [ICMP_ADDRESSREPLY] = {
1166 .handler = icmp_discard,
1167 },
1168 };
1169
icmp_sk_exit(struct net * net)1170 static void __net_exit icmp_sk_exit(struct net *net)
1171 {
1172 int i;
1173
1174 for_each_possible_cpu(i)
1175 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1176 free_percpu(net->ipv4.icmp_sk);
1177 net->ipv4.icmp_sk = NULL;
1178 }
1179
icmp_sk_init(struct net * net)1180 static int __net_init icmp_sk_init(struct net *net)
1181 {
1182 int i, err;
1183
1184 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1185 if (!net->ipv4.icmp_sk)
1186 return -ENOMEM;
1187
1188 for_each_possible_cpu(i) {
1189 struct sock *sk;
1190
1191 err = inet_ctl_sock_create(&sk, PF_INET,
1192 SOCK_RAW, IPPROTO_ICMP, net);
1193 if (err < 0)
1194 goto fail;
1195
1196 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1197
1198 /* Enough space for 2 64K ICMP packets, including
1199 * sk_buff/skb_shared_info struct overhead.
1200 */
1201 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1202
1203 /*
1204 * Speedup sock_wfree()
1205 */
1206 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1207 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1208 }
1209
1210 /* Control parameters for ECHO replies. */
1211 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1212 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1213
1214 /* Control parameter - ignore bogus broadcast responses? */
1215 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1216
1217 /*
1218 * Configurable global rate limit.
1219 *
1220 * ratelimit defines tokens/packet consumed for dst->rate_token
1221 * bucket ratemask defines which icmp types are ratelimited by
1222 * setting it's bit position.
1223 *
1224 * default:
1225 * dest unreachable (3), source quench (4),
1226 * time exceeded (11), parameter problem (12)
1227 */
1228
1229 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1230 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1231 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1232
1233 return 0;
1234
1235 fail:
1236 for_each_possible_cpu(i)
1237 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1238 free_percpu(net->ipv4.icmp_sk);
1239 return err;
1240 }
1241
1242 static struct pernet_operations __net_initdata icmp_sk_ops = {
1243 .init = icmp_sk_init,
1244 .exit = icmp_sk_exit,
1245 };
1246
icmp_init(void)1247 int __init icmp_init(void)
1248 {
1249 return register_pernet_subsys(&icmp_sk_ops);
1250 }
1251