1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * NET3: Implementation of the ICMP protocol layer.
4 *
5 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
6 *
7 * Some of the function names and the icmp unreach table for this
8 * module were derived from [icmp.c 1.0.11 06/02/93] by
9 * Ross Biro, Fred N. van Kempen, Mark Evans, Alan Cox, Gerhard Koerting.
10 * Other than that this module is a complete rewrite.
11 *
12 * Fixes:
13 * Clemens Fruhwirth : introduce global icmp rate limiting
14 * with icmp type masking ability instead
15 * of broken per type icmp timeouts.
16 * Mike Shaver : RFC1122 checks.
17 * Alan Cox : Multicast ping reply as self.
18 * Alan Cox : Fix atomicity lockup in ip_build_xmit
19 * call.
20 * Alan Cox : Added 216,128 byte paths to the MTU
21 * code.
22 * Martin Mares : RFC1812 checks.
23 * Martin Mares : Can be configured to follow redirects
24 * if acting as a router _without_ a
25 * routing protocol (RFC 1812).
26 * Martin Mares : Echo requests may be configured to
27 * be ignored (RFC 1812).
28 * Martin Mares : Limitation of ICMP error message
29 * transmit rate (RFC 1812).
30 * Martin Mares : TOS and Precedence set correctly
31 * (RFC 1812).
32 * Martin Mares : Now copying as much data from the
33 * original packet as we can without
34 * exceeding 576 bytes (RFC 1812).
35 * Willy Konynenberg : Transparent proxying support.
36 * Keith Owens : RFC1191 correction for 4.2BSD based
37 * path MTU bug.
38 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
39 * valid (RFC 1812).
40 * Andi Kleen : Check all packet lengths properly
41 * and moved all kfree_skb() up to
42 * icmp_rcv.
43 * Andi Kleen : Move the rate limit bookkeeping
44 * into the dest entry and use a token
45 * bucket filter (thanks to ANK). Make
46 * the rates sysctl configurable.
47 * Yu Tianli : Fixed two ugly bugs in icmp_send
48 * - IP option length was accounted wrongly
49 * - ICMP header length was not accounted
50 * at all.
51 * Tristan Greaves : Added sysctl option to ignore bogus
52 * broadcast responses from broken routers.
53 *
54 * To Fix:
55 *
56 * - Should use skb_pull() instead of all the manual checking.
57 * This would also greatly simply some upper layer error handlers. --AK
58 */
59
60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61
62 #include <linux/module.h>
63 #include <linux/types.h>
64 #include <linux/jiffies.h>
65 #include <linux/kernel.h>
66 #include <linux/fcntl.h>
67 #include <linux/socket.h>
68 #include <linux/in.h>
69 #include <linux/inet.h>
70 #include <linux/inetdevice.h>
71 #include <linux/netdevice.h>
72 #include <linux/string.h>
73 #include <linux/netfilter_ipv4.h>
74 #include <linux/slab.h>
75 #include <net/snmp.h>
76 #include <net/ip.h>
77 #include <net/route.h>
78 #include <net/protocol.h>
79 #include <net/icmp.h>
80 #include <net/tcp.h>
81 #include <net/udp.h>
82 #include <net/raw.h>
83 #include <net/ping.h>
84 #include <linux/skbuff.h>
85 #include <net/sock.h>
86 #include <linux/errno.h>
87 #include <linux/timer.h>
88 #include <linux/init.h>
89 #include <linux/uaccess.h>
90 #include <net/checksum.h>
91 #include <net/xfrm.h>
92 #include <net/inet_common.h>
93 #include <net/ip_fib.h>
94 #include <net/l3mdev.h>
95
96 /*
97 * Build xmit assembly blocks
98 */
99
100 struct icmp_bxm {
101 struct sk_buff *skb;
102 int offset;
103 int data_len;
104
105 struct {
106 struct icmphdr icmph;
107 __be32 times[3];
108 } data;
109 int head_len;
110 struct ip_options_data replyopts;
111 };
112
113 /* An array of errno for error messages from dest unreach. */
114 /* RFC 1122: 3.2.2.1 States that NET_UNREACH, HOST_UNREACH and SR_FAILED MUST be considered 'transient errs'. */
115
116 const struct icmp_err icmp_err_convert[] = {
117 {
118 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
119 .fatal = 0,
120 },
121 {
122 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
123 .fatal = 0,
124 },
125 {
126 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
127 .fatal = 1,
128 },
129 {
130 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
131 .fatal = 1,
132 },
133 {
134 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
135 .fatal = 0,
136 },
137 {
138 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
139 .fatal = 0,
140 },
141 {
142 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
143 .fatal = 1,
144 },
145 {
146 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
147 .fatal = 1,
148 },
149 {
150 .errno = ENONET, /* ICMP_HOST_ISOLATED */
151 .fatal = 1,
152 },
153 {
154 .errno = ENETUNREACH, /* ICMP_NET_ANO */
155 .fatal = 1,
156 },
157 {
158 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
159 .fatal = 1,
160 },
161 {
162 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
163 .fatal = 0,
164 },
165 {
166 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
167 .fatal = 0,
168 },
169 {
170 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
171 .fatal = 1,
172 },
173 {
174 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
175 .fatal = 1,
176 },
177 {
178 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
179 .fatal = 1,
180 },
181 };
182 EXPORT_SYMBOL(icmp_err_convert);
183
184 /*
185 * ICMP control array. This specifies what to do with each ICMP.
186 */
187
188 struct icmp_control {
189 bool (*handler)(struct sk_buff *skb);
190 short error; /* This ICMP is classed as an error message */
191 };
192
193 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
194
195 /*
196 * The ICMP socket(s). This is the most convenient way to flow control
197 * our ICMP output as well as maintain a clean interface throughout
198 * all layers. All Socketless IP sends will soon be gone.
199 *
200 * On SMP we have one ICMP socket per-cpu.
201 */
icmp_sk(struct net * net)202 static struct sock *icmp_sk(struct net *net)
203 {
204 return this_cpu_read(*net->ipv4.icmp_sk);
205 }
206
207 /* Called with BH disabled */
icmp_xmit_lock(struct net * net)208 static inline struct sock *icmp_xmit_lock(struct net *net)
209 {
210 struct sock *sk;
211
212 sk = icmp_sk(net);
213
214 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
215 /* This can happen if the output path signals a
216 * dst_link_failure() for an outgoing ICMP packet.
217 */
218 return NULL;
219 }
220 return sk;
221 }
222
icmp_xmit_unlock(struct sock * sk)223 static inline void icmp_xmit_unlock(struct sock *sk)
224 {
225 spin_unlock(&sk->sk_lock.slock);
226 }
227
228 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
229 int sysctl_icmp_msgs_burst __read_mostly = 50;
230
231 static struct {
232 spinlock_t lock;
233 u32 credit;
234 u32 stamp;
235 } icmp_global = {
236 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
237 };
238
239 /**
240 * icmp_global_allow - Are we allowed to send one more ICMP message ?
241 *
242 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
243 * Returns false if we reached the limit and can not send another packet.
244 * Note: called with BH disabled
245 */
icmp_global_allow(void)246 bool icmp_global_allow(void)
247 {
248 u32 credit, delta, incr = 0, now = (u32)jiffies;
249 bool rc = false;
250
251 /* Check if token bucket is empty and cannot be refilled
252 * without taking the spinlock. The READ_ONCE() are paired
253 * with the following WRITE_ONCE() in this same function.
254 */
255 if (!READ_ONCE(icmp_global.credit)) {
256 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
257 if (delta < HZ / 50)
258 return false;
259 }
260
261 spin_lock(&icmp_global.lock);
262 delta = min_t(u32, now - icmp_global.stamp, HZ);
263 if (delta >= HZ / 50) {
264 incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
265 if (incr)
266 WRITE_ONCE(icmp_global.stamp, now);
267 }
268 credit = min_t(u32, icmp_global.credit + incr,
269 READ_ONCE(sysctl_icmp_msgs_burst));
270 if (credit) {
271 /* We want to use a credit of one in average, but need to randomize
272 * it for security reasons.
273 */
274 credit = max_t(int, credit - prandom_u32_max(3), 0);
275 rc = true;
276 }
277 WRITE_ONCE(icmp_global.credit, credit);
278 spin_unlock(&icmp_global.lock);
279 return rc;
280 }
281 EXPORT_SYMBOL(icmp_global_allow);
282
icmpv4_mask_allow(struct net * net,int type,int code)283 static bool icmpv4_mask_allow(struct net *net, int type, int code)
284 {
285 if (type > NR_ICMP_TYPES)
286 return true;
287
288 /* Don't limit PMTU discovery. */
289 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
290 return true;
291
292 /* Limit if icmp type is enabled in ratemask. */
293 if (!((1 << type) & READ_ONCE(net->ipv4.sysctl_icmp_ratemask)))
294 return true;
295
296 return false;
297 }
298
icmpv4_global_allow(struct net * net,int type,int code)299 static bool icmpv4_global_allow(struct net *net, int type, int code)
300 {
301 if (icmpv4_mask_allow(net, type, code))
302 return true;
303
304 if (icmp_global_allow())
305 return true;
306
307 return false;
308 }
309
310 /*
311 * Send an ICMP frame.
312 */
313
icmpv4_xrlim_allow(struct net * net,struct rtable * rt,struct flowi4 * fl4,int type,int code)314 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
315 struct flowi4 *fl4, int type, int code)
316 {
317 struct dst_entry *dst = &rt->dst;
318 struct inet_peer *peer;
319 bool rc = true;
320 int vif;
321
322 if (icmpv4_mask_allow(net, type, code))
323 goto out;
324
325 /* No rate limit on loopback */
326 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
327 goto out;
328
329 vif = l3mdev_master_ifindex(dst->dev);
330 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
331 rc = inet_peer_xrlim_allow(peer,
332 READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
333 if (peer)
334 inet_putpeer(peer);
335 out:
336 return rc;
337 }
338
339 /*
340 * Maintain the counters used in the SNMP statistics for outgoing ICMP
341 */
icmp_out_count(struct net * net,unsigned char type)342 void icmp_out_count(struct net *net, unsigned char type)
343 {
344 ICMPMSGOUT_INC_STATS(net, type);
345 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
346 }
347
348 /*
349 * Checksum each fragment, and on the first include the headers and final
350 * checksum.
351 */
icmp_glue_bits(void * from,char * to,int offset,int len,int odd,struct sk_buff * skb)352 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
353 struct sk_buff *skb)
354 {
355 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
356 __wsum csum;
357
358 csum = skb_copy_and_csum_bits(icmp_param->skb,
359 icmp_param->offset + offset,
360 to, len);
361
362 skb->csum = csum_block_add(skb->csum, csum, odd);
363 if (icmp_pointers[icmp_param->data.icmph.type].error)
364 nf_ct_attach(skb, icmp_param->skb);
365 return 0;
366 }
367
icmp_push_reply(struct icmp_bxm * icmp_param,struct flowi4 * fl4,struct ipcm_cookie * ipc,struct rtable ** rt)368 static void icmp_push_reply(struct icmp_bxm *icmp_param,
369 struct flowi4 *fl4,
370 struct ipcm_cookie *ipc, struct rtable **rt)
371 {
372 struct sock *sk;
373 struct sk_buff *skb;
374
375 sk = icmp_sk(dev_net((*rt)->dst.dev));
376 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
377 icmp_param->data_len+icmp_param->head_len,
378 icmp_param->head_len,
379 ipc, rt, MSG_DONTWAIT) < 0) {
380 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
381 ip_flush_pending_frames(sk);
382 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
383 struct icmphdr *icmph = icmp_hdr(skb);
384 __wsum csum;
385 struct sk_buff *skb1;
386
387 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
388 (char *)icmph,
389 icmp_param->head_len);
390 skb_queue_walk(&sk->sk_write_queue, skb1) {
391 csum = csum_add(csum, skb1->csum);
392 }
393 icmph->checksum = csum_fold(csum);
394 skb->ip_summed = CHECKSUM_NONE;
395 ip_push_pending_frames(sk, fl4);
396 }
397 }
398
399 /*
400 * Driving logic for building and sending ICMP messages.
401 */
402
icmp_reply(struct icmp_bxm * icmp_param,struct sk_buff * skb)403 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
404 {
405 struct ipcm_cookie ipc;
406 struct rtable *rt = skb_rtable(skb);
407 struct net *net = dev_net(rt->dst.dev);
408 struct flowi4 fl4;
409 struct sock *sk;
410 struct inet_sock *inet;
411 __be32 daddr, saddr;
412 u32 mark = IP4_REPLY_MARK(net, skb->mark);
413 int type = icmp_param->data.icmph.type;
414 int code = icmp_param->data.icmph.code;
415
416 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
417 return;
418
419 /* Needed by both icmp_global_allow and icmp_xmit_lock */
420 local_bh_disable();
421
422 /* global icmp_msgs_per_sec */
423 if (!icmpv4_global_allow(net, type, code))
424 goto out_bh_enable;
425
426 sk = icmp_xmit_lock(net);
427 if (!sk)
428 goto out_bh_enable;
429 inet = inet_sk(sk);
430
431 icmp_param->data.icmph.checksum = 0;
432
433 ipcm_init(&ipc);
434 inet->tos = ip_hdr(skb)->tos;
435 ipc.sockc.mark = mark;
436 daddr = ipc.addr = ip_hdr(skb)->saddr;
437 saddr = fib_compute_spec_dst(skb);
438
439 if (icmp_param->replyopts.opt.opt.optlen) {
440 ipc.opt = &icmp_param->replyopts.opt;
441 if (ipc.opt->opt.srr)
442 daddr = icmp_param->replyopts.opt.opt.faddr;
443 }
444 memset(&fl4, 0, sizeof(fl4));
445 fl4.daddr = daddr;
446 fl4.saddr = saddr;
447 fl4.flowi4_mark = mark;
448 fl4.flowi4_uid = sock_net_uid(net, NULL);
449 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
450 fl4.flowi4_proto = IPPROTO_ICMP;
451 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
452 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
453 rt = ip_route_output_key(net, &fl4);
454 if (IS_ERR(rt))
455 goto out_unlock;
456 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
457 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
458 ip_rt_put(rt);
459 out_unlock:
460 icmp_xmit_unlock(sk);
461 out_bh_enable:
462 local_bh_enable();
463 }
464
465 /*
466 * The device used for looking up which routing table to use for sending an ICMP
467 * error is preferably the source whenever it is set, which should ensure the
468 * icmp error can be sent to the source host, else lookup using the routing
469 * table of the destination device, else use the main routing table (index 0).
470 */
icmp_get_route_lookup_dev(struct sk_buff * skb)471 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
472 {
473 struct net_device *route_lookup_dev = NULL;
474
475 if (skb->dev)
476 route_lookup_dev = skb->dev;
477 else if (skb_dst(skb))
478 route_lookup_dev = skb_dst(skb)->dev;
479 return route_lookup_dev;
480 }
481
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)482 static struct rtable *icmp_route_lookup(struct net *net,
483 struct flowi4 *fl4,
484 struct sk_buff *skb_in,
485 const struct iphdr *iph,
486 __be32 saddr, u8 tos, u32 mark,
487 int type, int code,
488 struct icmp_bxm *param)
489 {
490 struct net_device *route_lookup_dev;
491 struct rtable *rt, *rt2;
492 struct flowi4 fl4_dec;
493 int err;
494
495 memset(fl4, 0, sizeof(*fl4));
496 fl4->daddr = (param->replyopts.opt.opt.srr ?
497 param->replyopts.opt.opt.faddr : iph->saddr);
498 fl4->saddr = saddr;
499 fl4->flowi4_mark = mark;
500 fl4->flowi4_uid = sock_net_uid(net, NULL);
501 fl4->flowi4_tos = RT_TOS(tos);
502 fl4->flowi4_proto = IPPROTO_ICMP;
503 fl4->fl4_icmp_type = type;
504 fl4->fl4_icmp_code = code;
505 route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
506 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
507
508 security_skb_classify_flow(skb_in, flowi4_to_flowi_common(fl4));
509 rt = ip_route_output_key_hash(net, fl4, skb_in);
510 if (IS_ERR(rt))
511 return rt;
512
513 /* No need to clone since we're just using its address. */
514 rt2 = rt;
515
516 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
517 flowi4_to_flowi(fl4), NULL, 0);
518 if (!IS_ERR(rt)) {
519 if (rt != rt2)
520 return rt;
521 } else if (PTR_ERR(rt) == -EPERM) {
522 rt = NULL;
523 } else
524 return rt;
525
526 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
527 if (err)
528 goto relookup_failed;
529
530 if (inet_addr_type_dev_table(net, route_lookup_dev,
531 fl4_dec.saddr) == RTN_LOCAL) {
532 rt2 = __ip_route_output_key(net, &fl4_dec);
533 if (IS_ERR(rt2))
534 err = PTR_ERR(rt2);
535 } else {
536 struct flowi4 fl4_2 = {};
537 unsigned long orefdst;
538
539 fl4_2.daddr = fl4_dec.saddr;
540 rt2 = ip_route_output_key(net, &fl4_2);
541 if (IS_ERR(rt2)) {
542 err = PTR_ERR(rt2);
543 goto relookup_failed;
544 }
545 /* Ugh! */
546 orefdst = skb_in->_skb_refdst; /* save old refdst */
547 skb_dst_set(skb_in, NULL);
548 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
549 RT_TOS(tos), rt2->dst.dev);
550
551 dst_release(&rt2->dst);
552 rt2 = skb_rtable(skb_in);
553 skb_in->_skb_refdst = orefdst; /* restore old refdst */
554 }
555
556 if (err)
557 goto relookup_failed;
558
559 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
560 flowi4_to_flowi(&fl4_dec), NULL,
561 XFRM_LOOKUP_ICMP);
562 if (!IS_ERR(rt2)) {
563 dst_release(&rt->dst);
564 memcpy(fl4, &fl4_dec, sizeof(*fl4));
565 rt = rt2;
566 } else if (PTR_ERR(rt2) == -EPERM) {
567 if (rt)
568 dst_release(&rt->dst);
569 return rt2;
570 } else {
571 err = PTR_ERR(rt2);
572 goto relookup_failed;
573 }
574 return rt;
575
576 relookup_failed:
577 if (rt)
578 return rt;
579 return ERR_PTR(err);
580 }
581
582 /*
583 * Send an ICMP message in response to a situation
584 *
585 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
586 * MAY send more (we do).
587 * MUST NOT change this header information.
588 * MUST NOT reply to a multicast/broadcast IP address.
589 * MUST NOT reply to a multicast/broadcast MAC address.
590 * MUST reply to only the first fragment.
591 */
592
__icmp_send(struct sk_buff * skb_in,int type,int code,__be32 info,const struct ip_options * opt)593 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
594 const struct ip_options *opt)
595 {
596 struct iphdr *iph;
597 int room;
598 struct icmp_bxm icmp_param;
599 struct rtable *rt = skb_rtable(skb_in);
600 struct ipcm_cookie ipc;
601 struct flowi4 fl4;
602 __be32 saddr;
603 u8 tos;
604 u32 mark;
605 struct net *net;
606 struct sock *sk;
607
608 if (!rt)
609 goto out;
610
611 if (rt->dst.dev)
612 net = dev_net(rt->dst.dev);
613 else if (skb_in->dev)
614 net = dev_net(skb_in->dev);
615 else
616 goto out;
617
618 /*
619 * Find the original header. It is expected to be valid, of course.
620 * Check this, icmp_send is called from the most obscure devices
621 * sometimes.
622 */
623 iph = ip_hdr(skb_in);
624
625 if ((u8 *)iph < skb_in->head ||
626 (skb_network_header(skb_in) + sizeof(*iph)) >
627 skb_tail_pointer(skb_in))
628 goto out;
629
630 /*
631 * No replies to physical multicast/broadcast
632 */
633 if (skb_in->pkt_type != PACKET_HOST)
634 goto out;
635
636 /*
637 * Now check at the protocol level
638 */
639 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
640 goto out;
641
642 /*
643 * Only reply to fragment 0. We byte re-order the constant
644 * mask for efficiency.
645 */
646 if (iph->frag_off & htons(IP_OFFSET))
647 goto out;
648
649 /*
650 * If we send an ICMP error to an ICMP error a mess would result..
651 */
652 if (icmp_pointers[type].error) {
653 /*
654 * We are an error, check if we are replying to an
655 * ICMP error
656 */
657 if (iph->protocol == IPPROTO_ICMP) {
658 u8 _inner_type, *itp;
659
660 itp = skb_header_pointer(skb_in,
661 skb_network_header(skb_in) +
662 (iph->ihl << 2) +
663 offsetof(struct icmphdr,
664 type) -
665 skb_in->data,
666 sizeof(_inner_type),
667 &_inner_type);
668 if (!itp)
669 goto out;
670
671 /*
672 * Assume any unknown ICMP type is an error. This
673 * isn't specified by the RFC, but think about it..
674 */
675 if (*itp > NR_ICMP_TYPES ||
676 icmp_pointers[*itp].error)
677 goto out;
678 }
679 }
680
681 /* Needed by both icmp_global_allow and icmp_xmit_lock */
682 local_bh_disable();
683
684 /* Check global sysctl_icmp_msgs_per_sec ratelimit, unless
685 * incoming dev is loopback. If outgoing dev change to not be
686 * loopback, then peer ratelimit still work (in icmpv4_xrlim_allow)
687 */
688 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
689 !icmpv4_global_allow(net, type, code))
690 goto out_bh_enable;
691
692 sk = icmp_xmit_lock(net);
693 if (!sk)
694 goto out_bh_enable;
695
696 /*
697 * Construct source address and options.
698 */
699
700 saddr = iph->daddr;
701 if (!(rt->rt_flags & RTCF_LOCAL)) {
702 struct net_device *dev = NULL;
703
704 rcu_read_lock();
705 if (rt_is_input_route(rt) &&
706 READ_ONCE(net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr))
707 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
708
709 if (dev)
710 saddr = inet_select_addr(dev, iph->saddr,
711 RT_SCOPE_LINK);
712 else
713 saddr = 0;
714 rcu_read_unlock();
715 }
716
717 tos = icmp_pointers[type].error ? (RT_TOS(iph->tos) |
718 IPTOS_PREC_INTERNETCONTROL) :
719 iph->tos;
720 mark = IP4_REPLY_MARK(net, skb_in->mark);
721
722 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
723 goto out_unlock;
724
725
726 /*
727 * Prepare data for ICMP header.
728 */
729
730 icmp_param.data.icmph.type = type;
731 icmp_param.data.icmph.code = code;
732 icmp_param.data.icmph.un.gateway = info;
733 icmp_param.data.icmph.checksum = 0;
734 icmp_param.skb = skb_in;
735 icmp_param.offset = skb_network_offset(skb_in);
736 inet_sk(sk)->tos = tos;
737 ipcm_init(&ipc);
738 ipc.addr = iph->saddr;
739 ipc.opt = &icmp_param.replyopts.opt;
740 ipc.sockc.mark = mark;
741
742 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
743 type, code, &icmp_param);
744 if (IS_ERR(rt))
745 goto out_unlock;
746
747 /* peer icmp_ratelimit */
748 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
749 goto ende;
750
751 /* RFC says return as much as we can without exceeding 576 bytes. */
752
753 room = dst_mtu(&rt->dst);
754 if (room > 576)
755 room = 576;
756 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
757 room -= sizeof(struct icmphdr);
758 /* Guard against tiny mtu. We need to include at least one
759 * IP network header for this message to make any sense.
760 */
761 if (room <= (int)sizeof(struct iphdr))
762 goto ende;
763
764 icmp_param.data_len = skb_in->len - icmp_param.offset;
765 if (icmp_param.data_len > room)
766 icmp_param.data_len = room;
767 icmp_param.head_len = sizeof(struct icmphdr);
768
769 /* if we don't have a source address at this point, fall back to the
770 * dummy address instead of sending out a packet with a source address
771 * of 0.0.0.0
772 */
773 if (!fl4.saddr)
774 fl4.saddr = htonl(INADDR_DUMMY);
775
776 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
777 ende:
778 ip_rt_put(rt);
779 out_unlock:
780 icmp_xmit_unlock(sk);
781 out_bh_enable:
782 local_bh_enable();
783 out:;
784 }
785 EXPORT_SYMBOL(__icmp_send);
786
787 #if IS_ENABLED(CONFIG_NF_NAT)
788 #include <net/netfilter/nf_conntrack.h>
icmp_ndo_send(struct sk_buff * skb_in,int type,int code,__be32 info)789 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
790 {
791 struct sk_buff *cloned_skb = NULL;
792 struct ip_options opts = { 0 };
793 enum ip_conntrack_info ctinfo;
794 struct nf_conn *ct;
795 __be32 orig_ip;
796
797 ct = nf_ct_get(skb_in, &ctinfo);
798 if (!ct || !(ct->status & IPS_SRC_NAT)) {
799 __icmp_send(skb_in, type, code, info, &opts);
800 return;
801 }
802
803 if (skb_shared(skb_in))
804 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
805
806 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
807 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
808 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
809 skb_network_offset(skb_in) + sizeof(struct iphdr))))
810 goto out;
811
812 orig_ip = ip_hdr(skb_in)->saddr;
813 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
814 __icmp_send(skb_in, type, code, info, &opts);
815 ip_hdr(skb_in)->saddr = orig_ip;
816 out:
817 consume_skb(cloned_skb);
818 }
819 EXPORT_SYMBOL(icmp_ndo_send);
820 #endif
821
icmp_socket_deliver(struct sk_buff * skb,u32 info)822 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
823 {
824 const struct iphdr *iph = (const struct iphdr *)skb->data;
825 const struct net_protocol *ipprot;
826 int protocol = iph->protocol;
827
828 /* Checkin full IP header plus 8 bytes of protocol to
829 * avoid additional coding at protocol handlers.
830 */
831 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
832 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
833 return;
834 }
835
836 raw_icmp_error(skb, protocol, info);
837
838 ipprot = rcu_dereference(inet_protos[protocol]);
839 if (ipprot && ipprot->err_handler)
840 ipprot->err_handler(skb, info);
841 }
842
icmp_tag_validation(int proto)843 static bool icmp_tag_validation(int proto)
844 {
845 bool ok;
846
847 rcu_read_lock();
848 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
849 rcu_read_unlock();
850 return ok;
851 }
852
853 /*
854 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
855 * ICMP_PARAMETERPROB.
856 */
857
icmp_unreach(struct sk_buff * skb)858 static bool icmp_unreach(struct sk_buff *skb)
859 {
860 const struct iphdr *iph;
861 struct icmphdr *icmph;
862 struct net *net;
863 u32 info = 0;
864
865 net = dev_net(skb_dst(skb)->dev);
866
867 /*
868 * Incomplete header ?
869 * Only checks for the IP header, there should be an
870 * additional check for longer headers in upper levels.
871 */
872
873 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
874 goto out_err;
875
876 icmph = icmp_hdr(skb);
877 iph = (const struct iphdr *)skb->data;
878
879 if (iph->ihl < 5) /* Mangled header, drop. */
880 goto out_err;
881
882 switch (icmph->type) {
883 case ICMP_DEST_UNREACH:
884 switch (icmph->code & 15) {
885 case ICMP_NET_UNREACH:
886 case ICMP_HOST_UNREACH:
887 case ICMP_PROT_UNREACH:
888 case ICMP_PORT_UNREACH:
889 break;
890 case ICMP_FRAG_NEEDED:
891 /* for documentation of the ip_no_pmtu_disc
892 * values please see
893 * Documentation/networking/ip-sysctl.rst
894 */
895 switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
896 default:
897 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
898 &iph->daddr);
899 break;
900 case 2:
901 goto out;
902 case 3:
903 if (!icmp_tag_validation(iph->protocol))
904 goto out;
905 fallthrough;
906 case 0:
907 info = ntohs(icmph->un.frag.mtu);
908 }
909 break;
910 case ICMP_SR_FAILED:
911 net_dbg_ratelimited("%pI4: Source Route Failed\n",
912 &iph->daddr);
913 break;
914 default:
915 break;
916 }
917 if (icmph->code > NR_ICMP_UNREACH)
918 goto out;
919 break;
920 case ICMP_PARAMETERPROB:
921 info = ntohl(icmph->un.gateway) >> 24;
922 break;
923 case ICMP_TIME_EXCEEDED:
924 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
925 if (icmph->code == ICMP_EXC_FRAGTIME)
926 goto out;
927 break;
928 }
929
930 /*
931 * Throw it at our lower layers
932 *
933 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
934 * header.
935 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
936 * transport layer.
937 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
938 * transport layer.
939 */
940
941 /*
942 * Check the other end isn't violating RFC 1122. Some routers send
943 * bogus responses to broadcast frames. If you see this message
944 * first check your netmask matches at both ends, if it does then
945 * get the other vendor to fix their kit.
946 */
947
948 if (!READ_ONCE(net->ipv4.sysctl_icmp_ignore_bogus_error_responses) &&
949 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
950 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
951 &ip_hdr(skb)->saddr,
952 icmph->type, icmph->code,
953 &iph->daddr, skb->dev->name);
954 goto out;
955 }
956
957 icmp_socket_deliver(skb, info);
958
959 out:
960 return true;
961 out_err:
962 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
963 return false;
964 }
965
966
967 /*
968 * Handle ICMP_REDIRECT.
969 */
970
icmp_redirect(struct sk_buff * skb)971 static bool icmp_redirect(struct sk_buff *skb)
972 {
973 if (skb->len < sizeof(struct iphdr)) {
974 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
975 return false;
976 }
977
978 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
979 /* there aught to be a stat */
980 return false;
981 }
982
983 icmp_socket_deliver(skb, ntohl(icmp_hdr(skb)->un.gateway));
984 return true;
985 }
986
987 /*
988 * Handle ICMP_ECHO ("ping") and ICMP_EXT_ECHO ("PROBE") requests.
989 *
990 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
991 * requests.
992 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
993 * included in the reply.
994 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
995 * echo requests, MUST have default=NOT.
996 * RFC 8335: 8 MUST have a config option to enable/disable ICMP
997 * Extended Echo Functionality, MUST be disabled by default
998 * See also WRT handling of options once they are done and working.
999 */
1000
icmp_echo(struct sk_buff * skb)1001 static bool icmp_echo(struct sk_buff *skb)
1002 {
1003 struct icmp_bxm icmp_param;
1004 struct net *net;
1005
1006 net = dev_net(skb_dst(skb)->dev);
1007 /* should there be an ICMP stat for ignored echos? */
1008 if (net->ipv4.sysctl_icmp_echo_ignore_all)
1009 return true;
1010
1011 icmp_param.data.icmph = *icmp_hdr(skb);
1012 icmp_param.skb = skb;
1013 icmp_param.offset = 0;
1014 icmp_param.data_len = skb->len;
1015 icmp_param.head_len = sizeof(struct icmphdr);
1016
1017 if (icmp_param.data.icmph.type == ICMP_ECHO)
1018 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1019 else if (!icmp_build_probe(skb, &icmp_param.data.icmph))
1020 return true;
1021
1022 icmp_reply(&icmp_param, skb);
1023 return true;
1024 }
1025
1026 /* Helper for icmp_echo and icmpv6_echo_reply.
1027 * Searches for net_device that matches PROBE interface identifier
1028 * and builds PROBE reply message in icmphdr.
1029 *
1030 * Returns false if PROBE responses are disabled via sysctl
1031 */
1032
icmp_build_probe(struct sk_buff * skb,struct icmphdr * icmphdr)1033 bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
1034 {
1035 struct icmp_ext_hdr *ext_hdr, _ext_hdr;
1036 struct icmp_ext_echo_iio *iio, _iio;
1037 struct net *net = dev_net(skb->dev);
1038 struct net_device *dev;
1039 char buff[IFNAMSIZ];
1040 u16 ident_len;
1041 u8 status;
1042
1043 if (!READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe))
1044 return false;
1045
1046 /* We currently only support probing interfaces on the proxy node
1047 * Check to ensure L-bit is set
1048 */
1049 if (!(ntohs(icmphdr->un.echo.sequence) & 1))
1050 return false;
1051 /* Clear status bits in reply message */
1052 icmphdr->un.echo.sequence &= htons(0xFF00);
1053 if (icmphdr->type == ICMP_EXT_ECHO)
1054 icmphdr->type = ICMP_EXT_ECHOREPLY;
1055 else
1056 icmphdr->type = ICMPV6_EXT_ECHO_REPLY;
1057 ext_hdr = skb_header_pointer(skb, 0, sizeof(_ext_hdr), &_ext_hdr);
1058 /* Size of iio is class_type dependent.
1059 * Only check header here and assign length based on ctype in the switch statement
1060 */
1061 iio = skb_header_pointer(skb, sizeof(_ext_hdr), sizeof(iio->extobj_hdr), &_iio);
1062 if (!ext_hdr || !iio)
1063 goto send_mal_query;
1064 if (ntohs(iio->extobj_hdr.length) <= sizeof(iio->extobj_hdr) ||
1065 ntohs(iio->extobj_hdr.length) > sizeof(_iio))
1066 goto send_mal_query;
1067 ident_len = ntohs(iio->extobj_hdr.length) - sizeof(iio->extobj_hdr);
1068 iio = skb_header_pointer(skb, sizeof(_ext_hdr),
1069 sizeof(iio->extobj_hdr) + ident_len, &_iio);
1070 if (!iio)
1071 goto send_mal_query;
1072
1073 status = 0;
1074 dev = NULL;
1075 switch (iio->extobj_hdr.class_type) {
1076 case ICMP_EXT_ECHO_CTYPE_NAME:
1077 if (ident_len >= IFNAMSIZ)
1078 goto send_mal_query;
1079 memset(buff, 0, sizeof(buff));
1080 memcpy(buff, &iio->ident.name, ident_len);
1081 dev = dev_get_by_name(net, buff);
1082 break;
1083 case ICMP_EXT_ECHO_CTYPE_INDEX:
1084 if (ident_len != sizeof(iio->ident.ifindex))
1085 goto send_mal_query;
1086 dev = dev_get_by_index(net, ntohl(iio->ident.ifindex));
1087 break;
1088 case ICMP_EXT_ECHO_CTYPE_ADDR:
1089 if (ident_len < sizeof(iio->ident.addr.ctype3_hdr) ||
1090 ident_len != sizeof(iio->ident.addr.ctype3_hdr) +
1091 iio->ident.addr.ctype3_hdr.addrlen)
1092 goto send_mal_query;
1093 switch (ntohs(iio->ident.addr.ctype3_hdr.afi)) {
1094 case ICMP_AFI_IP:
1095 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in_addr))
1096 goto send_mal_query;
1097 dev = ip_dev_find(net, iio->ident.addr.ip_addr.ipv4_addr);
1098 break;
1099 #if IS_ENABLED(CONFIG_IPV6)
1100 case ICMP_AFI_IP6:
1101 if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr))
1102 goto send_mal_query;
1103 dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev);
1104 dev_hold(dev);
1105 break;
1106 #endif
1107 default:
1108 goto send_mal_query;
1109 }
1110 break;
1111 default:
1112 goto send_mal_query;
1113 }
1114 if (!dev) {
1115 icmphdr->code = ICMP_EXT_CODE_NO_IF;
1116 return true;
1117 }
1118 /* Fill bits in reply message */
1119 if (dev->flags & IFF_UP)
1120 status |= ICMP_EXT_ECHOREPLY_ACTIVE;
1121 if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)
1122 status |= ICMP_EXT_ECHOREPLY_IPV4;
1123 if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))
1124 status |= ICMP_EXT_ECHOREPLY_IPV6;
1125 dev_put(dev);
1126 icmphdr->un.echo.sequence |= htons(status);
1127 return true;
1128 send_mal_query:
1129 icmphdr->code = ICMP_EXT_CODE_MAL_QUERY;
1130 return true;
1131 }
1132 EXPORT_SYMBOL_GPL(icmp_build_probe);
1133
1134 /*
1135 * Handle ICMP Timestamp requests.
1136 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1137 * SHOULD be in the kernel for minimum random latency.
1138 * MUST be accurate to a few minutes.
1139 * MUST be updated at least at 15Hz.
1140 */
icmp_timestamp(struct sk_buff * skb)1141 static bool icmp_timestamp(struct sk_buff *skb)
1142 {
1143 struct icmp_bxm icmp_param;
1144 /*
1145 * Too short.
1146 */
1147 if (skb->len < 4)
1148 goto out_err;
1149
1150 /*
1151 * Fill in the current time as ms since midnight UT:
1152 */
1153 icmp_param.data.times[1] = inet_current_timestamp();
1154 icmp_param.data.times[2] = icmp_param.data.times[1];
1155
1156 BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
1157
1158 icmp_param.data.icmph = *icmp_hdr(skb);
1159 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1160 icmp_param.data.icmph.code = 0;
1161 icmp_param.skb = skb;
1162 icmp_param.offset = 0;
1163 icmp_param.data_len = 0;
1164 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1165 icmp_reply(&icmp_param, skb);
1166 return true;
1167
1168 out_err:
1169 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1170 return false;
1171 }
1172
icmp_discard(struct sk_buff * skb)1173 static bool icmp_discard(struct sk_buff *skb)
1174 {
1175 /* pretend it was a success */
1176 return true;
1177 }
1178
1179 /*
1180 * Deal with incoming ICMP packets.
1181 */
icmp_rcv(struct sk_buff * skb)1182 int icmp_rcv(struct sk_buff *skb)
1183 {
1184 struct icmphdr *icmph;
1185 struct rtable *rt = skb_rtable(skb);
1186 struct net *net = dev_net(rt->dst.dev);
1187 bool success;
1188
1189 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1190 struct sec_path *sp = skb_sec_path(skb);
1191 int nh;
1192
1193 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1194 XFRM_STATE_ICMP))
1195 goto drop;
1196
1197 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1198 goto drop;
1199
1200 nh = skb_network_offset(skb);
1201 skb_set_network_header(skb, sizeof(*icmph));
1202
1203 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1204 goto drop;
1205
1206 skb_set_network_header(skb, nh);
1207 }
1208
1209 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1210
1211 if (skb_checksum_simple_validate(skb))
1212 goto csum_error;
1213
1214 if (!pskb_pull(skb, sizeof(*icmph)))
1215 goto error;
1216
1217 icmph = icmp_hdr(skb);
1218
1219 ICMPMSGIN_INC_STATS(net, icmph->type);
1220
1221 /* Check for ICMP Extended Echo (PROBE) messages */
1222 if (icmph->type == ICMP_EXT_ECHO) {
1223 /* We can't use icmp_pointers[].handler() because it is an array of
1224 * size NR_ICMP_TYPES + 1 (19 elements) and PROBE has code 42.
1225 */
1226 success = icmp_echo(skb);
1227 goto success_check;
1228 }
1229
1230 if (icmph->type == ICMP_EXT_ECHOREPLY) {
1231 success = ping_rcv(skb);
1232 goto success_check;
1233 }
1234
1235 /*
1236 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1237 *
1238 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1239 * discarded.
1240 */
1241 if (icmph->type > NR_ICMP_TYPES)
1242 goto error;
1243
1244 /*
1245 * Parse the ICMP message
1246 */
1247
1248 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1249 /*
1250 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1251 * silently ignored (we let user decide with a sysctl).
1252 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1253 * discarded if to broadcast/multicast.
1254 */
1255 if ((icmph->type == ICMP_ECHO ||
1256 icmph->type == ICMP_TIMESTAMP) &&
1257 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1258 goto error;
1259 }
1260 if (icmph->type != ICMP_ECHO &&
1261 icmph->type != ICMP_TIMESTAMP &&
1262 icmph->type != ICMP_ADDRESS &&
1263 icmph->type != ICMP_ADDRESSREPLY) {
1264 goto error;
1265 }
1266 }
1267
1268 success = icmp_pointers[icmph->type].handler(skb);
1269 success_check:
1270 if (success) {
1271 consume_skb(skb);
1272 return NET_RX_SUCCESS;
1273 }
1274
1275 drop:
1276 kfree_skb(skb);
1277 return NET_RX_DROP;
1278 csum_error:
1279 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1280 error:
1281 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1282 goto drop;
1283 }
1284
ip_icmp_error_rfc4884_validate(const struct sk_buff * skb,int off)1285 static bool ip_icmp_error_rfc4884_validate(const struct sk_buff *skb, int off)
1286 {
1287 struct icmp_extobj_hdr *objh, _objh;
1288 struct icmp_ext_hdr *exth, _exth;
1289 u16 olen;
1290
1291 exth = skb_header_pointer(skb, off, sizeof(_exth), &_exth);
1292 if (!exth)
1293 return false;
1294 if (exth->version != 2)
1295 return true;
1296
1297 if (exth->checksum &&
1298 csum_fold(skb_checksum(skb, off, skb->len - off, 0)))
1299 return false;
1300
1301 off += sizeof(_exth);
1302 while (off < skb->len) {
1303 objh = skb_header_pointer(skb, off, sizeof(_objh), &_objh);
1304 if (!objh)
1305 return false;
1306
1307 olen = ntohs(objh->length);
1308 if (olen < sizeof(_objh))
1309 return false;
1310
1311 off += olen;
1312 if (off > skb->len)
1313 return false;
1314 }
1315
1316 return true;
1317 }
1318
ip_icmp_error_rfc4884(const struct sk_buff * skb,struct sock_ee_data_rfc4884 * out,int thlen,int off)1319 void ip_icmp_error_rfc4884(const struct sk_buff *skb,
1320 struct sock_ee_data_rfc4884 *out,
1321 int thlen, int off)
1322 {
1323 int hlen;
1324
1325 /* original datagram headers: end of icmph to payload (skb->data) */
1326 hlen = -skb_transport_offset(skb) - thlen;
1327
1328 /* per rfc 4884: minimal datagram length of 128 bytes */
1329 if (off < 128 || off < hlen)
1330 return;
1331
1332 /* kernel has stripped headers: return payload offset in bytes */
1333 off -= hlen;
1334 if (off + sizeof(struct icmp_ext_hdr) > skb->len)
1335 return;
1336
1337 out->len = off;
1338
1339 if (!ip_icmp_error_rfc4884_validate(skb, off))
1340 out->flags |= SO_EE_RFC4884_FLAG_INVALID;
1341 }
1342 EXPORT_SYMBOL_GPL(ip_icmp_error_rfc4884);
1343
icmp_err(struct sk_buff * skb,u32 info)1344 int icmp_err(struct sk_buff *skb, u32 info)
1345 {
1346 struct iphdr *iph = (struct iphdr *)skb->data;
1347 int offset = iph->ihl<<2;
1348 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1349 int type = icmp_hdr(skb)->type;
1350 int code = icmp_hdr(skb)->code;
1351 struct net *net = dev_net(skb->dev);
1352
1353 /*
1354 * Use ping_err to handle all icmp errors except those
1355 * triggered by ICMP_ECHOREPLY which sent from kernel.
1356 */
1357 if (icmph->type != ICMP_ECHOREPLY) {
1358 ping_err(skb, offset, info);
1359 return 0;
1360 }
1361
1362 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1363 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ICMP);
1364 else if (type == ICMP_REDIRECT)
1365 ipv4_redirect(skb, net, 0, IPPROTO_ICMP);
1366
1367 return 0;
1368 }
1369
1370 /*
1371 * This table is the definition of how we handle ICMP.
1372 */
1373 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1374 [ICMP_ECHOREPLY] = {
1375 .handler = ping_rcv,
1376 },
1377 [1] = {
1378 .handler = icmp_discard,
1379 .error = 1,
1380 },
1381 [2] = {
1382 .handler = icmp_discard,
1383 .error = 1,
1384 },
1385 [ICMP_DEST_UNREACH] = {
1386 .handler = icmp_unreach,
1387 .error = 1,
1388 },
1389 [ICMP_SOURCE_QUENCH] = {
1390 .handler = icmp_unreach,
1391 .error = 1,
1392 },
1393 [ICMP_REDIRECT] = {
1394 .handler = icmp_redirect,
1395 .error = 1,
1396 },
1397 [6] = {
1398 .handler = icmp_discard,
1399 .error = 1,
1400 },
1401 [7] = {
1402 .handler = icmp_discard,
1403 .error = 1,
1404 },
1405 [ICMP_ECHO] = {
1406 .handler = icmp_echo,
1407 },
1408 [9] = {
1409 .handler = icmp_discard,
1410 .error = 1,
1411 },
1412 [10] = {
1413 .handler = icmp_discard,
1414 .error = 1,
1415 },
1416 [ICMP_TIME_EXCEEDED] = {
1417 .handler = icmp_unreach,
1418 .error = 1,
1419 },
1420 [ICMP_PARAMETERPROB] = {
1421 .handler = icmp_unreach,
1422 .error = 1,
1423 },
1424 [ICMP_TIMESTAMP] = {
1425 .handler = icmp_timestamp,
1426 },
1427 [ICMP_TIMESTAMPREPLY] = {
1428 .handler = icmp_discard,
1429 },
1430 [ICMP_INFO_REQUEST] = {
1431 .handler = icmp_discard,
1432 },
1433 [ICMP_INFO_REPLY] = {
1434 .handler = icmp_discard,
1435 },
1436 [ICMP_ADDRESS] = {
1437 .handler = icmp_discard,
1438 },
1439 [ICMP_ADDRESSREPLY] = {
1440 .handler = icmp_discard,
1441 },
1442 };
1443
icmp_sk_exit(struct net * net)1444 static void __net_exit icmp_sk_exit(struct net *net)
1445 {
1446 int i;
1447
1448 for_each_possible_cpu(i)
1449 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1450 free_percpu(net->ipv4.icmp_sk);
1451 net->ipv4.icmp_sk = NULL;
1452 }
1453
icmp_sk_init(struct net * net)1454 static int __net_init icmp_sk_init(struct net *net)
1455 {
1456 int i, err;
1457
1458 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1459 if (!net->ipv4.icmp_sk)
1460 return -ENOMEM;
1461
1462 for_each_possible_cpu(i) {
1463 struct sock *sk;
1464
1465 err = inet_ctl_sock_create(&sk, PF_INET,
1466 SOCK_RAW, IPPROTO_ICMP, net);
1467 if (err < 0)
1468 goto fail;
1469
1470 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1471
1472 /* Enough space for 2 64K ICMP packets, including
1473 * sk_buff/skb_shared_info struct overhead.
1474 */
1475 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1476
1477 /*
1478 * Speedup sock_wfree()
1479 */
1480 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1481 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1482 }
1483
1484 /* Control parameters for ECHO replies. */
1485 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1486 net->ipv4.sysctl_icmp_echo_enable_probe = 0;
1487 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1488
1489 /* Control parameter - ignore bogus broadcast responses? */
1490 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1491
1492 /*
1493 * Configurable global rate limit.
1494 *
1495 * ratelimit defines tokens/packet consumed for dst->rate_token
1496 * bucket ratemask defines which icmp types are ratelimited by
1497 * setting it's bit position.
1498 *
1499 * default:
1500 * dest unreachable (3), source quench (4),
1501 * time exceeded (11), parameter problem (12)
1502 */
1503
1504 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1505 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1506 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1507
1508 return 0;
1509
1510 fail:
1511 icmp_sk_exit(net);
1512 return err;
1513 }
1514
1515 static struct pernet_operations __net_initdata icmp_sk_ops = {
1516 .init = icmp_sk_init,
1517 .exit = icmp_sk_exit,
1518 };
1519
icmp_init(void)1520 int __init icmp_init(void)
1521 {
1522 return register_pernet_subsys(&icmp_sk_ops);
1523 }
1524