2 * NET3: Implementation of the ICMP protocol layer.
4 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
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.
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.
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
24 * Alan Cox : Added 216,128 byte paths to the MTU
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
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
42 * Thomas Quinot : ICMP Dest Unreach codes up to 15 are
44 * Andi Kleen : Check all packet lengths properly
45 * and moved all kfree_skb() up to
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
55 * Tristan Greaves : Added sysctl option to ignore bogus
56 * broadcast responses from broken routers.
60 * - Should use skb_pull() instead of all the manual checking.
61 * This would also greatly simply some upper layer error handlers. --AK
65 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
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>
82 #include <net/route.h>
83 #include <net/protocol.h>
89 #include <linux/skbuff.h>
91 #include <linux/errno.h>
92 #include <linux/timer.h>
93 #include <linux/init.h>
94 #include <linux/uaccess.h>
95 #include <net/checksum.h>
97 #include <net/inet_common.h>
98 #include <net/ip_fib.h>
99 #include <net/l3mdev.h>
102 * Build xmit assembly blocks
111 struct icmphdr icmph;
115 struct ip_options_data replyopts;
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'. */
121 const struct icmp_err icmp_err_convert[] = {
123 .errno = ENETUNREACH, /* ICMP_NET_UNREACH */
127 .errno = EHOSTUNREACH, /* ICMP_HOST_UNREACH */
131 .errno = ENOPROTOOPT /* ICMP_PROT_UNREACH */,
135 .errno = ECONNREFUSED, /* ICMP_PORT_UNREACH */
139 .errno = EMSGSIZE, /* ICMP_FRAG_NEEDED */
143 .errno = EOPNOTSUPP, /* ICMP_SR_FAILED */
147 .errno = ENETUNREACH, /* ICMP_NET_UNKNOWN */
151 .errno = EHOSTDOWN, /* ICMP_HOST_UNKNOWN */
155 .errno = ENONET, /* ICMP_HOST_ISOLATED */
159 .errno = ENETUNREACH, /* ICMP_NET_ANO */
163 .errno = EHOSTUNREACH, /* ICMP_HOST_ANO */
167 .errno = ENETUNREACH, /* ICMP_NET_UNR_TOS */
171 .errno = EHOSTUNREACH, /* ICMP_HOST_UNR_TOS */
175 .errno = EHOSTUNREACH, /* ICMP_PKT_FILTERED */
179 .errno = EHOSTUNREACH, /* ICMP_PREC_VIOLATION */
183 .errno = EHOSTUNREACH, /* ICMP_PREC_CUTOFF */
187 EXPORT_SYMBOL(icmp_err_convert);
190 * ICMP control array. This specifies what to do with each ICMP.
193 struct icmp_control {
194 bool (*handler)(struct sk_buff *skb);
195 short error; /* This ICMP is classed as an error message */
198 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES+1];
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.
205 * On SMP we have one ICMP socket per-cpu.
207 static struct sock *icmp_sk(struct net *net)
209 return *this_cpu_ptr(net->ipv4.icmp_sk);
212 /* Called with BH disabled */
213 static inline struct sock *icmp_xmit_lock(struct net *net)
219 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {
220 /* This can happen if the output path signals a
221 * dst_link_failure() for an outgoing ICMP packet.
228 static inline void icmp_xmit_unlock(struct sock *sk)
230 spin_unlock(&sk->sk_lock.slock);
233 int sysctl_icmp_msgs_per_sec __read_mostly = 1000;
234 int sysctl_icmp_msgs_burst __read_mostly = 50;
241 .lock = __SPIN_LOCK_UNLOCKED(icmp_global.lock),
245 * icmp_global_allow - Are we allowed to send one more ICMP message ?
247 * Uses a token bucket to limit our ICMP messages to ~sysctl_icmp_msgs_per_sec.
248 * Returns false if we reached the limit and can not send another packet.
249 * Note: called with BH disabled
251 bool icmp_global_allow(void)
253 u32 credit, delta, incr = 0, now = (u32)jiffies;
256 /* Check if token bucket is empty and cannot be refilled
257 * without taking the spinlock. The READ_ONCE() are paired
258 * with the following WRITE_ONCE() in this same function.
260 if (!READ_ONCE(icmp_global.credit)) {
261 delta = min_t(u32, now - READ_ONCE(icmp_global.stamp), HZ);
266 spin_lock(&icmp_global.lock);
267 delta = min_t(u32, now - icmp_global.stamp, HZ);
268 if (delta >= HZ / 50) {
269 incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
271 WRITE_ONCE(icmp_global.stamp, now);
273 credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
275 /* We want to use a credit of one in average, but need to randomize
276 * it for security reasons.
278 credit = max_t(int, credit - prandom_u32_max(3), 0);
281 WRITE_ONCE(icmp_global.credit, credit);
282 spin_unlock(&icmp_global.lock);
285 EXPORT_SYMBOL(icmp_global_allow);
287 static bool icmpv4_mask_allow(struct net *net, int type, int code)
289 if (type > NR_ICMP_TYPES)
292 /* Don't limit PMTU discovery. */
293 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
296 /* Limit if icmp type is enabled in ratemask. */
297 if (!((1 << type) & net->ipv4.sysctl_icmp_ratemask))
303 static bool icmpv4_global_allow(struct net *net, int type, int code)
305 if (icmpv4_mask_allow(net, type, code))
308 if (icmp_global_allow())
315 * Send an ICMP frame.
318 static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
319 struct flowi4 *fl4, int type, int code)
321 struct dst_entry *dst = &rt->dst;
322 struct inet_peer *peer;
326 if (icmpv4_mask_allow(net, type, code))
329 /* No rate limit on loopback */
330 if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
333 vif = l3mdev_master_ifindex(dst->dev);
334 peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr, vif, 1);
335 rc = inet_peer_xrlim_allow(peer, net->ipv4.sysctl_icmp_ratelimit);
343 * Maintain the counters used in the SNMP statistics for outgoing ICMP
345 void icmp_out_count(struct net *net, unsigned char type)
347 ICMPMSGOUT_INC_STATS(net, type);
348 ICMP_INC_STATS(net, ICMP_MIB_OUTMSGS);
352 * Checksum each fragment, and on the first include the headers and final
355 static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
358 struct icmp_bxm *icmp_param = (struct icmp_bxm *)from;
361 csum = skb_copy_and_csum_bits(icmp_param->skb,
362 icmp_param->offset + offset,
365 skb->csum = csum_block_add(skb->csum, csum, odd);
366 if (icmp_pointers[icmp_param->data.icmph.type].error)
367 nf_ct_attach(skb, icmp_param->skb);
371 static void icmp_push_reply(struct icmp_bxm *icmp_param,
373 struct ipcm_cookie *ipc, struct rtable **rt)
378 sk = icmp_sk(dev_net((*rt)->dst.dev));
379 if (ip_append_data(sk, fl4, icmp_glue_bits, icmp_param,
380 icmp_param->data_len+icmp_param->head_len,
381 icmp_param->head_len,
382 ipc, rt, MSG_DONTWAIT) < 0) {
383 __ICMP_INC_STATS(sock_net(sk), ICMP_MIB_OUTERRORS);
384 ip_flush_pending_frames(sk);
385 } else if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
386 struct icmphdr *icmph = icmp_hdr(skb);
388 struct sk_buff *skb1;
390 skb_queue_walk(&sk->sk_write_queue, skb1) {
391 csum = csum_add(csum, skb1->csum);
393 csum = csum_partial_copy_nocheck((void *)&icmp_param->data,
395 icmp_param->head_len, csum);
396 icmph->checksum = csum_fold(csum);
397 skb->ip_summed = CHECKSUM_NONE;
398 ip_push_pending_frames(sk, fl4);
403 * Driving logic for building and sending ICMP messages.
406 static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
408 struct ipcm_cookie ipc;
409 struct rtable *rt = skb_rtable(skb);
410 struct net *net = dev_net(rt->dst.dev);
413 struct inet_sock *inet;
415 u32 mark = IP4_REPLY_MARK(net, skb->mark);
416 int type = icmp_param->data.icmph.type;
417 int code = icmp_param->data.icmph.code;
419 if (ip_options_echo(net, &icmp_param->replyopts.opt.opt, skb))
422 /* Needed by both icmp_global_allow and icmp_xmit_lock */
425 /* global icmp_msgs_per_sec */
426 if (!icmpv4_global_allow(net, type, code))
429 sk = icmp_xmit_lock(net);
434 icmp_param->data.icmph.checksum = 0;
436 inet->tos = ip_hdr(skb)->tos;
438 daddr = ipc.addr = ip_hdr(skb)->saddr;
439 saddr = fib_compute_spec_dst(skb);
445 if (icmp_param->replyopts.opt.opt.optlen) {
446 ipc.opt = &icmp_param->replyopts.opt;
447 if (ipc.opt->opt.srr)
448 daddr = icmp_param->replyopts.opt.opt.faddr;
450 memset(&fl4, 0, sizeof(fl4));
453 fl4.flowi4_mark = mark;
454 fl4.flowi4_uid = sock_net_uid(net, NULL);
455 fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
456 fl4.flowi4_proto = IPPROTO_ICMP;
457 fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
458 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
459 rt = ip_route_output_key(net, &fl4);
462 if (icmpv4_xrlim_allow(net, rt, &fl4, type, code))
463 icmp_push_reply(icmp_param, &fl4, &ipc, &rt);
466 icmp_xmit_unlock(sk);
472 * The device used for looking up which routing table to use for sending an ICMP
473 * error is preferably the source whenever it is set, which should ensure the
474 * icmp error can be sent to the source host, else lookup using the routing
475 * table of the destination device, else use the main routing table (index 0).
477 static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
479 struct net_device *route_lookup_dev = NULL;
482 route_lookup_dev = skb->dev;
483 else if (skb_dst(skb))
484 route_lookup_dev = skb_dst(skb)->dev;
485 return route_lookup_dev;
488 static struct rtable *icmp_route_lookup(struct net *net,
490 struct sk_buff *skb_in,
491 const struct iphdr *iph,
492 __be32 saddr, u8 tos, u32 mark,
494 struct icmp_bxm *param)
496 struct net_device *route_lookup_dev;
497 struct rtable *rt, *rt2;
498 struct flowi4 fl4_dec;
501 memset(fl4, 0, sizeof(*fl4));
502 fl4->daddr = (param->replyopts.opt.opt.srr ?
503 param->replyopts.opt.opt.faddr : iph->saddr);
505 fl4->flowi4_mark = mark;
506 fl4->flowi4_uid = sock_net_uid(net, NULL);
507 fl4->flowi4_tos = RT_TOS(tos);
508 fl4->flowi4_proto = IPPROTO_ICMP;
509 fl4->fl4_icmp_type = type;
510 fl4->fl4_icmp_code = code;
511 route_lookup_dev = icmp_get_route_lookup_dev(skb_in);
512 fl4->flowi4_oif = l3mdev_master_ifindex(route_lookup_dev);
514 security_skb_classify_flow(skb_in, flowi4_to_flowi(fl4));
515 rt = ip_route_output_key_hash(net, fl4, skb_in);
519 /* No need to clone since we're just using its address. */
522 rt = (struct rtable *) xfrm_lookup(net, &rt->dst,
523 flowi4_to_flowi(fl4), NULL, 0);
527 } else if (PTR_ERR(rt) == -EPERM) {
532 err = xfrm_decode_session_reverse(skb_in, flowi4_to_flowi(&fl4_dec), AF_INET);
534 goto relookup_failed;
536 if (inet_addr_type_dev_table(net, route_lookup_dev,
537 fl4_dec.saddr) == RTN_LOCAL) {
538 rt2 = __ip_route_output_key(net, &fl4_dec);
542 struct flowi4 fl4_2 = {};
543 unsigned long orefdst;
545 fl4_2.daddr = fl4_dec.saddr;
546 rt2 = ip_route_output_key(net, &fl4_2);
549 goto relookup_failed;
552 orefdst = skb_in->_skb_refdst; /* save old refdst */
553 skb_dst_set(skb_in, NULL);
554 err = ip_route_input(skb_in, fl4_dec.daddr, fl4_dec.saddr,
555 RT_TOS(tos), rt2->dst.dev);
557 dst_release(&rt2->dst);
558 rt2 = skb_rtable(skb_in);
559 skb_in->_skb_refdst = orefdst; /* restore old refdst */
563 goto relookup_failed;
565 rt2 = (struct rtable *) xfrm_lookup(net, &rt2->dst,
566 flowi4_to_flowi(&fl4_dec), NULL,
569 dst_release(&rt->dst);
570 memcpy(fl4, &fl4_dec, sizeof(*fl4));
572 } else if (PTR_ERR(rt2) == -EPERM) {
574 dst_release(&rt->dst);
578 goto relookup_failed;
589 * Send an ICMP message in response to a situation
591 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header.
592 * MAY send more (we do).
593 * MUST NOT change this header information.
594 * MUST NOT reply to a multicast/broadcast IP address.
595 * MUST NOT reply to a multicast/broadcast MAC address.
596 * MUST reply to only the first fragment.
599 void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
600 const struct ip_options *opt)
604 struct icmp_bxm icmp_param;
605 struct rtable *rt = skb_rtable(skb_in);
606 struct ipcm_cookie ipc;
616 net = dev_net(rt->dst.dev);
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
623 iph = ip_hdr(skb_in);
625 if ((u8 *)iph < skb_in->head ||
626 (skb_network_header(skb_in) + sizeof(*iph)) >
627 skb_tail_pointer(skb_in))
631 * No replies to physical multicast/broadcast
633 if (skb_in->pkt_type != PACKET_HOST)
637 * Now check at the protocol level
639 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
643 * Only reply to fragment 0. We byte re-order the constant
644 * mask for efficiency.
646 if (iph->frag_off & htons(IP_OFFSET))
650 * If we send an ICMP error to an ICMP error a mess would result..
652 if (icmp_pointers[type].error) {
654 * We are an error, check if we are replying to an
657 if (iph->protocol == IPPROTO_ICMP) {
658 u8 _inner_type, *itp;
660 itp = skb_header_pointer(skb_in,
661 skb_network_header(skb_in) +
663 offsetof(struct icmphdr,
672 * Assume any unknown ICMP type is an error. This
673 * isn't specified by the RFC, but think about it..
675 if (*itp > NR_ICMP_TYPES ||
676 icmp_pointers[*itp].error)
681 /* Needed by both icmp_global_allow and icmp_xmit_lock */
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)
688 if (!(skb_in->dev && (skb_in->dev->flags&IFF_LOOPBACK)) &&
689 !icmpv4_global_allow(net, type, code))
692 sk = icmp_xmit_lock(net);
697 * Construct source address and options.
701 if (!(rt->rt_flags & RTCF_LOCAL)) {
702 struct net_device *dev = NULL;
705 if (rt_is_input_route(rt) &&
706 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr)
707 dev = dev_get_by_index_rcu(net, inet_iif(skb_in));
710 saddr = inet_select_addr(dev, 0, RT_SCOPE_LINK);
716 tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) |
717 IPTOS_PREC_INTERNETCONTROL) :
719 mark = IP4_REPLY_MARK(net, skb_in->mark);
721 if (__ip_options_echo(net, &icmp_param.replyopts.opt.opt, skb_in, opt))
726 * Prepare data for ICMP header.
729 icmp_param.data.icmph.type = type;
730 icmp_param.data.icmph.code = code;
731 icmp_param.data.icmph.un.gateway = info;
732 icmp_param.data.icmph.checksum = 0;
733 icmp_param.skb = skb_in;
734 icmp_param.offset = skb_network_offset(skb_in);
735 inet_sk(sk)->tos = tos;
737 ipc.addr = iph->saddr;
738 ipc.opt = &icmp_param.replyopts.opt;
743 rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark,
744 type, code, &icmp_param);
748 /* peer icmp_ratelimit */
749 if (!icmpv4_xrlim_allow(net, rt, &fl4, type, code))
752 /* RFC says return as much as we can without exceeding 576 bytes. */
754 room = dst_mtu(&rt->dst);
757 room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen;
758 room -= sizeof(struct icmphdr);
760 icmp_param.data_len = skb_in->len - icmp_param.offset;
761 if (icmp_param.data_len > room)
762 icmp_param.data_len = room;
763 icmp_param.head_len = sizeof(struct icmphdr);
765 /* if we don't have a source address at this point, fall back to the
766 * dummy address instead of sending out a packet with a source address
770 fl4.saddr = htonl(INADDR_DUMMY);
772 icmp_push_reply(&icmp_param, &fl4, &ipc, &rt);
776 icmp_xmit_unlock(sk);
781 EXPORT_SYMBOL(__icmp_send);
783 #if IS_ENABLED(CONFIG_NF_NAT)
784 #include <net/netfilter/nf_conntrack.h>
785 void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
787 struct sk_buff *cloned_skb = NULL;
788 struct ip_options opts = { 0 };
789 enum ip_conntrack_info ctinfo;
793 ct = nf_ct_get(skb_in, &ctinfo);
794 if (!ct || !(ct->status & IPS_SRC_NAT)) {
795 __icmp_send(skb_in, type, code, info, &opts);
799 if (skb_shared(skb_in))
800 skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
802 if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
803 (skb_network_header(skb_in) + sizeof(struct iphdr)) >
804 skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
805 skb_network_offset(skb_in) + sizeof(struct iphdr))))
808 orig_ip = ip_hdr(skb_in)->saddr;
809 ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
810 __icmp_send(skb_in, type, code, info, &opts);
811 ip_hdr(skb_in)->saddr = orig_ip;
813 consume_skb(cloned_skb);
815 EXPORT_SYMBOL(icmp_ndo_send);
818 static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
820 const struct iphdr *iph = (const struct iphdr *) skb->data;
821 const struct net_protocol *ipprot;
822 int protocol = iph->protocol;
824 /* Checkin full IP header plus 8 bytes of protocol to
825 * avoid additional coding at protocol handlers.
827 if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
828 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
832 raw_icmp_error(skb, protocol, info);
834 ipprot = rcu_dereference(inet_protos[protocol]);
835 if (ipprot && ipprot->err_handler)
836 ipprot->err_handler(skb, info);
839 static bool icmp_tag_validation(int proto)
844 ok = rcu_dereference(inet_protos[proto])->icmp_strict_tag_validation;
850 * Handle ICMP_DEST_UNREACH, ICMP_TIME_EXCEEDED, ICMP_QUENCH, and
851 * ICMP_PARAMETERPROB.
854 static bool icmp_unreach(struct sk_buff *skb)
856 const struct iphdr *iph;
857 struct icmphdr *icmph;
861 net = dev_net(skb_dst(skb)->dev);
864 * Incomplete header ?
865 * Only checks for the IP header, there should be an
866 * additional check for longer headers in upper levels.
869 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
872 icmph = icmp_hdr(skb);
873 iph = (const struct iphdr *)skb->data;
875 if (iph->ihl < 5) /* Mangled header, drop. */
878 switch (icmph->type) {
879 case ICMP_DEST_UNREACH:
880 switch (icmph->code & 15) {
881 case ICMP_NET_UNREACH:
882 case ICMP_HOST_UNREACH:
883 case ICMP_PROT_UNREACH:
884 case ICMP_PORT_UNREACH:
886 case ICMP_FRAG_NEEDED:
887 /* for documentation of the ip_no_pmtu_disc
889 * Documentation/networking/ip-sysctl.txt
891 switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
893 net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
899 if (!icmp_tag_validation(iph->protocol))
903 info = ntohs(icmph->un.frag.mtu);
907 net_dbg_ratelimited("%pI4: Source Route Failed\n",
913 if (icmph->code > NR_ICMP_UNREACH)
916 case ICMP_PARAMETERPROB:
917 info = ntohl(icmph->un.gateway) >> 24;
919 case ICMP_TIME_EXCEEDED:
920 __ICMP_INC_STATS(net, ICMP_MIB_INTIMEEXCDS);
921 if (icmph->code == ICMP_EXC_FRAGTIME)
927 * Throw it at our lower layers
929 * RFC 1122: 3.2.2 MUST extract the protocol ID from the passed
931 * RFC 1122: 3.2.2.1 MUST pass ICMP unreach messages to the
933 * RFC 1122: 3.2.2.2 MUST pass ICMP time expired messages to
938 * Check the other end isn't violating RFC 1122. Some routers send
939 * bogus responses to broadcast frames. If you see this message
940 * first check your netmask matches at both ends, if it does then
941 * get the other vendor to fix their kit.
944 if (!net->ipv4.sysctl_icmp_ignore_bogus_error_responses &&
945 inet_addr_type_dev_table(net, skb->dev, iph->daddr) == RTN_BROADCAST) {
946 net_warn_ratelimited("%pI4 sent an invalid ICMP type %u, code %u error to a broadcast: %pI4 on %s\n",
948 icmph->type, icmph->code,
949 &iph->daddr, skb->dev->name);
953 icmp_socket_deliver(skb, info);
958 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
964 * Handle ICMP_REDIRECT.
967 static bool icmp_redirect(struct sk_buff *skb)
969 if (skb->len < sizeof(struct iphdr)) {
970 __ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
974 if (!pskb_may_pull(skb, sizeof(struct iphdr))) {
975 /* there aught to be a stat */
979 icmp_socket_deliver(skb, icmp_hdr(skb)->un.gateway);
984 * Handle ICMP_ECHO ("ping") requests.
986 * RFC 1122: 3.2.2.6 MUST have an echo server that answers ICMP echo
988 * RFC 1122: 3.2.2.6 Data received in the ICMP_ECHO request MUST be
989 * included in the reply.
990 * RFC 1812: 4.3.3.6 SHOULD have a config option for silently ignoring
991 * echo requests, MUST have default=NOT.
992 * See also WRT handling of options once they are done and working.
995 static bool icmp_echo(struct sk_buff *skb)
999 net = dev_net(skb_dst(skb)->dev);
1000 if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
1001 struct icmp_bxm icmp_param;
1003 icmp_param.data.icmph = *icmp_hdr(skb);
1004 icmp_param.data.icmph.type = ICMP_ECHOREPLY;
1005 icmp_param.skb = skb;
1006 icmp_param.offset = 0;
1007 icmp_param.data_len = skb->len;
1008 icmp_param.head_len = sizeof(struct icmphdr);
1009 icmp_reply(&icmp_param, skb);
1011 /* should there be an ICMP stat for ignored echos? */
1016 * Handle ICMP Timestamp requests.
1017 * RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
1018 * SHOULD be in the kernel for minimum random latency.
1019 * MUST be accurate to a few minutes.
1020 * MUST be updated at least at 15Hz.
1022 static bool icmp_timestamp(struct sk_buff *skb)
1024 struct icmp_bxm icmp_param;
1032 * Fill in the current time as ms since midnight UT:
1034 icmp_param.data.times[1] = inet_current_timestamp();
1035 icmp_param.data.times[2] = icmp_param.data.times[1];
1036 if (skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4))
1038 icmp_param.data.icmph = *icmp_hdr(skb);
1039 icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
1040 icmp_param.data.icmph.code = 0;
1041 icmp_param.skb = skb;
1042 icmp_param.offset = 0;
1043 icmp_param.data_len = 0;
1044 icmp_param.head_len = sizeof(struct icmphdr) + 12;
1045 icmp_reply(&icmp_param, skb);
1049 __ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
1053 static bool icmp_discard(struct sk_buff *skb)
1055 /* pretend it was a success */
1060 * Deal with incoming ICMP packets.
1062 int icmp_rcv(struct sk_buff *skb)
1064 struct icmphdr *icmph;
1065 struct rtable *rt = skb_rtable(skb);
1066 struct net *net = dev_net(rt->dst.dev);
1069 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
1070 struct sec_path *sp = skb_sec_path(skb);
1073 if (!(sp && sp->xvec[sp->len - 1]->props.flags &
1077 if (!pskb_may_pull(skb, sizeof(*icmph) + sizeof(struct iphdr)))
1080 nh = skb_network_offset(skb);
1081 skb_set_network_header(skb, sizeof(*icmph));
1083 if (!xfrm4_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
1086 skb_set_network_header(skb, nh);
1089 __ICMP_INC_STATS(net, ICMP_MIB_INMSGS);
1091 if (skb_checksum_simple_validate(skb))
1094 if (!pskb_pull(skb, sizeof(*icmph)))
1097 icmph = icmp_hdr(skb);
1099 ICMPMSGIN_INC_STATS(net, icmph->type);
1101 * 18 is the highest 'known' ICMP type. Anything else is a mystery
1103 * RFC 1122: 3.2.2 Unknown ICMP messages types MUST be silently
1106 if (icmph->type > NR_ICMP_TYPES)
1111 * Parse the ICMP message
1114 if (rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
1116 * RFC 1122: 3.2.2.6 An ICMP_ECHO to broadcast MAY be
1117 * silently ignored (we let user decide with a sysctl).
1118 * RFC 1122: 3.2.2.8 An ICMP_TIMESTAMP MAY be silently
1119 * discarded if to broadcast/multicast.
1121 if ((icmph->type == ICMP_ECHO ||
1122 icmph->type == ICMP_TIMESTAMP) &&
1123 net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
1126 if (icmph->type != ICMP_ECHO &&
1127 icmph->type != ICMP_TIMESTAMP &&
1128 icmph->type != ICMP_ADDRESS &&
1129 icmph->type != ICMP_ADDRESSREPLY) {
1134 success = icmp_pointers[icmph->type].handler(skb);
1138 return NET_RX_SUCCESS;
1145 __ICMP_INC_STATS(net, ICMP_MIB_CSUMERRORS);
1147 __ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
1151 void icmp_err(struct sk_buff *skb, u32 info)
1153 struct iphdr *iph = (struct iphdr *)skb->data;
1154 int offset = iph->ihl<<2;
1155 struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
1156 int type = icmp_hdr(skb)->type;
1157 int code = icmp_hdr(skb)->code;
1158 struct net *net = dev_net(skb->dev);
1161 * Use ping_err to handle all icmp errors except those
1162 * triggered by ICMP_ECHOREPLY which sent from kernel.
1164 if (icmph->type != ICMP_ECHOREPLY) {
1165 ping_err(skb, offset, info);
1169 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
1170 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ICMP, 0);
1171 else if (type == ICMP_REDIRECT)
1172 ipv4_redirect(skb, net, 0, 0, IPPROTO_ICMP, 0);
1176 * This table is the definition of how we handle ICMP.
1178 static const struct icmp_control icmp_pointers[NR_ICMP_TYPES + 1] = {
1179 [ICMP_ECHOREPLY] = {
1180 .handler = ping_rcv,
1183 .handler = icmp_discard,
1187 .handler = icmp_discard,
1190 [ICMP_DEST_UNREACH] = {
1191 .handler = icmp_unreach,
1194 [ICMP_SOURCE_QUENCH] = {
1195 .handler = icmp_unreach,
1199 .handler = icmp_redirect,
1203 .handler = icmp_discard,
1207 .handler = icmp_discard,
1211 .handler = icmp_echo,
1214 .handler = icmp_discard,
1218 .handler = icmp_discard,
1221 [ICMP_TIME_EXCEEDED] = {
1222 .handler = icmp_unreach,
1225 [ICMP_PARAMETERPROB] = {
1226 .handler = icmp_unreach,
1229 [ICMP_TIMESTAMP] = {
1230 .handler = icmp_timestamp,
1232 [ICMP_TIMESTAMPREPLY] = {
1233 .handler = icmp_discard,
1235 [ICMP_INFO_REQUEST] = {
1236 .handler = icmp_discard,
1238 [ICMP_INFO_REPLY] = {
1239 .handler = icmp_discard,
1242 .handler = icmp_discard,
1244 [ICMP_ADDRESSREPLY] = {
1245 .handler = icmp_discard,
1249 static void __net_exit icmp_sk_exit(struct net *net)
1253 for_each_possible_cpu(i)
1254 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1255 free_percpu(net->ipv4.icmp_sk);
1256 net->ipv4.icmp_sk = NULL;
1259 static int __net_init icmp_sk_init(struct net *net)
1263 net->ipv4.icmp_sk = alloc_percpu(struct sock *);
1264 if (!net->ipv4.icmp_sk)
1267 for_each_possible_cpu(i) {
1270 err = inet_ctl_sock_create(&sk, PF_INET,
1271 SOCK_RAW, IPPROTO_ICMP, net);
1275 *per_cpu_ptr(net->ipv4.icmp_sk, i) = sk;
1277 /* Enough space for 2 64K ICMP packets, including
1278 * sk_buff/skb_shared_info struct overhead.
1280 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);
1283 * Speedup sock_wfree()
1285 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
1286 inet_sk(sk)->pmtudisc = IP_PMTUDISC_DONT;
1289 /* Control parameters for ECHO replies. */
1290 net->ipv4.sysctl_icmp_echo_ignore_all = 0;
1291 net->ipv4.sysctl_icmp_echo_ignore_broadcasts = 1;
1293 /* Control parameter - ignore bogus broadcast responses? */
1294 net->ipv4.sysctl_icmp_ignore_bogus_error_responses = 1;
1297 * Configurable global rate limit.
1299 * ratelimit defines tokens/packet consumed for dst->rate_token
1300 * bucket ratemask defines which icmp types are ratelimited by
1301 * setting it's bit position.
1304 * dest unreachable (3), source quench (4),
1305 * time exceeded (11), parameter problem (12)
1308 net->ipv4.sysctl_icmp_ratelimit = 1 * HZ;
1309 net->ipv4.sysctl_icmp_ratemask = 0x1818;
1310 net->ipv4.sysctl_icmp_errors_use_inbound_ifaddr = 0;
1315 for_each_possible_cpu(i)
1316 inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.icmp_sk, i));
1317 free_percpu(net->ipv4.icmp_sk);
1321 static struct pernet_operations __net_initdata icmp_sk_ops = {
1322 .init = icmp_sk_init,
1323 .exit = icmp_sk_exit,
1326 int __init icmp_init(void)
1328 return register_pernet_subsys(&icmp_sk_ops);