1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#include "opt_inet.h"
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/mbuf.h>
38#include <sys/protosw.h>
39#include <sys/socket.h>
40#include <sys/time.h>
41#include <sys/kernel.h>
42#include <sys/lock.h>
43#include <sys/sysctl.h>
44#include <sys/syslog.h>
45
46#include <net/if.h>
47#include <net/if_var.h>
48#include <net/if_private.h>
49#include <net/if_types.h>
50#include <net/route.h>
51#include <net/route/route_ctl.h>
52#include <net/route/nhop.h>
53#include <net/vnet.h>
54
55#include <netinet/in.h>
56#include <netinet/in_fib.h>
57#include <netinet/in_pcb.h>
58#include <netinet/in_systm.h>
59#include <netinet/in_var.h>
60#include <netinet/ip.h>
61#include <netinet/ip_icmp.h>
62#include <netinet/ip_var.h>
63#include <netinet/ip_options.h>
64#include <netinet/sctp.h>
65#include <netinet/tcp.h>
66#include <netinet/tcpip.h>
67#include <netinet/icmp_var.h>
68
69#ifdef INET
70
71#include <machine/in_cksum.h>
72
73#include <security/mac/mac_framework.h>
74#endif /* INET */
75
76extern ipproto_ctlinput_t	*ip_ctlprotox[];
77
78/*
79 * ICMP routines: error generation, receive packet processing, and
80 * routines to turnaround packets back to the originator, and
81 * host table maintenance routines.
82 */
83static int sysctl_icmplim_and_jitter(SYSCTL_HANDLER_ARGS);
84VNET_DEFINE_STATIC(u_int, icmplim) = 200;
85#define	V_icmplim			VNET(icmplim)
86SYSCTL_PROC(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLTYPE_UINT |
87    CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim), 0,
88    &sysctl_icmplim_and_jitter, "IU",
89    "Maximum number of ICMP responses per second");
90
91VNET_DEFINE_STATIC(int, icmplim_curr_jitter) = 0;
92#define V_icmplim_curr_jitter		VNET(icmplim_curr_jitter)
93VNET_DEFINE_STATIC(u_int, icmplim_jitter) = 16;
94#define	V_icmplim_jitter		VNET(icmplim_jitter)
95SYSCTL_PROC(_net_inet_icmp, OID_AUTO, icmplim_jitter, CTLTYPE_UINT |
96    CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim_jitter), 0,
97    &sysctl_icmplim_and_jitter, "IU",
98    "Random icmplim jitter adjustment limit");
99
100VNET_DEFINE_STATIC(int, icmplim_output) = 1;
101#define	V_icmplim_output		VNET(icmplim_output)
102SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
103	&VNET_NAME(icmplim_output), 0,
104	"Enable logging of ICMP response rate limiting");
105
106#ifdef INET
107VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
108VNET_PCPUSTAT_SYSINIT(icmpstat);
109SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
110    icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
111
112#ifdef VIMAGE
113VNET_PCPUSTAT_SYSUNINIT(icmpstat);
114#endif /* VIMAGE */
115
116VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0;
117#define	V_icmpmaskrepl			VNET(icmpmaskrepl)
118SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
119	&VNET_NAME(icmpmaskrepl), 0,
120	"Reply to ICMP Address Mask Request packets");
121
122VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0;
123#define	V_icmpmaskfake			VNET(icmpmaskfake)
124SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
125	&VNET_NAME(icmpmaskfake), 0,
126	"Fake reply to ICMP Address Mask Request packets");
127
128VNET_DEFINE(int, drop_redirect) = 0;
129#define	V_drop_redirect			VNET(drop_redirect)
130SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
131	&VNET_NAME(drop_redirect), 0,
132	"Ignore ICMP redirects");
133
134VNET_DEFINE_STATIC(int, log_redirect) = 0;
135#define	V_log_redirect			VNET(log_redirect)
136SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
137	&VNET_NAME(log_redirect), 0,
138	"Log ICMP redirects to the console");
139
140VNET_DEFINE_STATIC(int, redirtimeout) = 60 * 10; /* 10 minutes */
141#define	V_redirtimeout			VNET(redirtimeout)
142SYSCTL_INT(_net_inet_icmp, OID_AUTO, redirtimeout, CTLFLAG_VNET | CTLFLAG_RW,
143	&VNET_NAME(redirtimeout), 0,
144	"Delay in seconds before expiring redirect route");
145
146VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]);
147#define	V_reply_src			VNET(reply_src)
148SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
149	&VNET_NAME(reply_src), IFNAMSIZ,
150	"ICMP reply source for non-local packets");
151
152VNET_DEFINE_STATIC(int, icmp_rfi) = 0;
153#define	V_icmp_rfi			VNET(icmp_rfi)
154SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
155	&VNET_NAME(icmp_rfi), 0,
156	"ICMP reply from incoming interface for non-local packets");
157/* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */
158VNET_DEFINE_STATIC(int, icmp_quotelen) = 548;
159#define	V_icmp_quotelen			VNET(icmp_quotelen)
160SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
161	&VNET_NAME(icmp_quotelen), 0,
162	"Number of bytes from original packet to quote in ICMP reply");
163
164VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0;
165#define	V_icmpbmcastecho		VNET(icmpbmcastecho)
166SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
167	&VNET_NAME(icmpbmcastecho), 0,
168	"Reply to multicast ICMP Echo Request and Timestamp packets");
169
170VNET_DEFINE_STATIC(int, icmptstamprepl) = 1;
171#define	V_icmptstamprepl		VNET(icmptstamprepl)
172SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW,
173	&VNET_NAME(icmptstamprepl), 0,
174	"Respond to ICMP Timestamp packets");
175
176VNET_DEFINE_STATIC(int, error_keeptags) = 0;
177#define	V_error_keeptags		VNET(error_keeptags)
178SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
179	&VNET_NAME(error_keeptags), 0,
180	"ICMP error response keeps copy of mbuf_tags of original packet");
181
182#ifdef ICMPPRINTFS
183int	icmpprintfs = 0;
184#endif
185
186static void	icmp_reflect(struct mbuf *);
187static void	icmp_send(struct mbuf *, struct mbuf *);
188static int	icmp_verify_redirect_gateway(struct sockaddr_in *,
189    struct sockaddr_in *, struct sockaddr_in *, u_int);
190
191/*
192 * Kernel module interface for updating icmpstat.  The argument is an index
193 * into icmpstat treated as an array of u_long.  While this encodes the
194 * general layout of icmpstat into the caller, it doesn't encode its
195 * location, so that future changes to add, for example, per-CPU stats
196 * support won't cause binary compatibility problems for kernel modules.
197 */
198void
199kmod_icmpstat_inc(int statnum)
200{
201
202	counter_u64_add(VNET(icmpstat)[statnum], 1);
203}
204
205/*
206 * Generate an error packet of type error
207 * in response to bad packet ip.
208 */
209void
210icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
211{
212	struct ip *oip, *nip;
213	struct icmp *icp;
214	struct mbuf *m;
215	unsigned icmplen, icmpelen, nlen, oiphlen;
216
217	KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type",
218	    __func__));
219
220	if (type != ICMP_REDIRECT)
221		ICMPSTAT_INC(icps_error);
222	/*
223	 * Don't send error:
224	 *  if the original packet was encrypted.
225	 *  if not the first fragment of message.
226	 *  in response to a multicast or broadcast packet.
227	 *  if the old packet protocol was an ICMP error message.
228	 */
229	if (n->m_flags & M_DECRYPTED)
230		goto freeit;
231	if (n->m_flags & (M_BCAST|M_MCAST))
232		goto freeit;
233
234	/* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */
235	if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
236		goto freeit;
237	oip = mtod(n, struct ip *);
238	oiphlen = oip->ip_hl << 2;
239	if (n->m_len < oiphlen + ICMP_MINLEN)
240		goto freeit;
241#ifdef ICMPPRINTFS
242	if (icmpprintfs)
243		printf("icmp_error(%p, %x, %d)\n", oip, type, code);
244#endif
245	if (oip->ip_off & htons(~(IP_MF|IP_DF)))
246		goto freeit;
247	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
248	    !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip +
249		oiphlen))->icmp_type)) {
250		ICMPSTAT_INC(icps_oldicmp);
251		goto freeit;
252	}
253	/*
254	 * Calculate length to quote from original packet and
255	 * prevent the ICMP mbuf from overflowing.
256	 * Unfortunately this is non-trivial since ip_forward()
257	 * sends us truncated packets.
258	 */
259	nlen = m_length(n, NULL);
260	if (oip->ip_p == IPPROTO_TCP) {
261		struct tcphdr *th;
262		int tcphlen;
263
264		if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
265		    n->m_next == NULL)
266			goto stdreply;
267		if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
268		    (n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)
269			goto freeit;
270		oip = mtod(n, struct ip *);
271		th = mtodo(n, oiphlen);
272		tcphlen = th->th_off << 2;
273		if (tcphlen < sizeof(struct tcphdr))
274			goto freeit;
275		if (ntohs(oip->ip_len) < oiphlen + tcphlen)
276			goto freeit;
277		if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
278			goto stdreply;
279		if (n->m_len < oiphlen + tcphlen &&
280		    (n = m_pullup(n, oiphlen + tcphlen)) == NULL)
281			goto freeit;
282		oip = mtod(n, struct ip *);
283		icmpelen = max(tcphlen, min(V_icmp_quotelen,
284		    ntohs(oip->ip_len) - oiphlen));
285	} else if (oip->ip_p == IPPROTO_SCTP) {
286		struct sctphdr *sh;
287		struct sctp_chunkhdr *ch;
288
289		if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
290			goto stdreply;
291		if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
292		    n->m_next == NULL)
293			goto stdreply;
294		if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
295		    (n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
296			goto freeit;
297		oip = mtod(n, struct ip *);
298		icmpelen = max(sizeof(struct sctphdr),
299		    min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
300		sh = mtodo(n, oiphlen);
301		if (ntohl(sh->v_tag) == 0 &&
302		    ntohs(oip->ip_len) >= oiphlen +
303		    sizeof(struct sctphdr) + 8 &&
304		    (n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
305		     n->m_next != NULL)) {
306			if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
307			    (n = m_pullup(n, oiphlen +
308			    sizeof(struct sctphdr) + 8)) == NULL)
309				goto freeit;
310			oip = mtod(n, struct ip *);
311			sh = mtodo(n, oiphlen);
312			ch = (struct sctp_chunkhdr *)(sh + 1);
313			if (ch->chunk_type == SCTP_INITIATION) {
314				icmpelen = max(sizeof(struct sctphdr) + 8,
315				    min(V_icmp_quotelen, ntohs(oip->ip_len) -
316				    oiphlen));
317			}
318		}
319	} else
320stdreply:	icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) -
321		    oiphlen));
322
323	icmplen = min(oiphlen + icmpelen, nlen);
324	if (icmplen < sizeof(struct ip))
325		goto freeit;
326
327	if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
328		m = m_gethdr(M_NOWAIT, MT_DATA);
329	else
330		m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
331	if (m == NULL)
332		goto freeit;
333#ifdef MAC
334	mac_netinet_icmp_reply(n, m);
335#endif
336	icmplen = min(icmplen, M_TRAILINGSPACE(m) -
337	    sizeof(struct ip) - ICMP_MINLEN);
338	m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
339	m->m_data += sizeof(struct ip);
340	m->m_len = ICMP_MINLEN + icmplen;
341
342	/* XXX MRT  make the outgoing packet use the same FIB
343	 * that was associated with the incoming packet
344	 */
345	M_SETFIB(m, M_GETFIB(n));
346	icp = mtod(m, struct icmp *);
347	ICMPSTAT_INC2(icps_outhist, type);
348	icp->icmp_type = type;
349	if (type == ICMP_REDIRECT)
350		icp->icmp_gwaddr.s_addr = dest;
351	else {
352		icp->icmp_void = 0;
353		/*
354		 * The following assignments assume an overlay with the
355		 * just zeroed icmp_void field.
356		 */
357		if (type == ICMP_PARAMPROB) {
358			icp->icmp_pptr = code;
359			code = 0;
360		} else if (type == ICMP_UNREACH &&
361			code == ICMP_UNREACH_NEEDFRAG && mtu) {
362			icp->icmp_nextmtu = htons(mtu);
363		}
364	}
365	icp->icmp_code = code;
366
367	/*
368	 * Copy the quotation into ICMP message and
369	 * convert quoted IP header back to network representation.
370	 */
371	m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
372	nip = &icp->icmp_ip;
373
374	/*
375	 * Set up ICMP message mbuf and copy old IP header (without options
376	 * in front of ICMP message.
377	 * If the original mbuf was meant to bypass the firewall, the error
378	 * reply should bypass as well.
379	 */
380	m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
381	KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
382	    ("insufficient space for ip header"));
383	m->m_data -= sizeof(struct ip);
384	m->m_len += sizeof(struct ip);
385	m->m_pkthdr.len = m->m_len;
386	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
387	nip = mtod(m, struct ip *);
388	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
389	nip->ip_len = htons(m->m_len);
390	nip->ip_v = IPVERSION;
391	nip->ip_hl = 5;
392	nip->ip_p = IPPROTO_ICMP;
393	nip->ip_tos = 0;
394	nip->ip_off = 0;
395
396	if (V_error_keeptags)
397		m_tag_copy_chain(m, n, M_NOWAIT);
398
399	icmp_reflect(m);
400
401freeit:
402	m_freem(n);
403}
404
405int
406icmp_errmap(const struct icmp *icp)
407{
408
409	switch (icp->icmp_type) {
410	case ICMP_UNREACH:
411		switch (icp->icmp_code) {
412		case ICMP_UNREACH_NET:
413		case ICMP_UNREACH_HOST:
414		case ICMP_UNREACH_SRCFAIL:
415		case ICMP_UNREACH_NET_UNKNOWN:
416		case ICMP_UNREACH_HOST_UNKNOWN:
417		case ICMP_UNREACH_ISOLATED:
418		case ICMP_UNREACH_TOSNET:
419		case ICMP_UNREACH_TOSHOST:
420		case ICMP_UNREACH_HOST_PRECEDENCE:
421		case ICMP_UNREACH_PRECEDENCE_CUTOFF:
422			return (EHOSTUNREACH);
423		case ICMP_UNREACH_NEEDFRAG:
424			return (EMSGSIZE);
425		case ICMP_UNREACH_PROTOCOL:
426		case ICMP_UNREACH_PORT:
427		case ICMP_UNREACH_NET_PROHIB:
428		case ICMP_UNREACH_HOST_PROHIB:
429		case ICMP_UNREACH_FILTER_PROHIB:
430			return (ECONNREFUSED);
431		default:
432			return (0);
433		}
434	case ICMP_TIMXCEED:
435		switch (icp->icmp_code) {
436		case ICMP_TIMXCEED_INTRANS:
437			return (EHOSTUNREACH);
438		default:
439			return (0);
440		}
441	case ICMP_PARAMPROB:
442		switch (icp->icmp_code) {
443		case ICMP_PARAMPROB_ERRATPTR:
444		case ICMP_PARAMPROB_OPTABSENT:
445			return (ENOPROTOOPT);
446		default:
447			return (0);
448		}
449	default:
450		return (0);
451	}
452}
453
454/*
455 * Process a received ICMP message.
456 */
457int
458icmp_input(struct mbuf **mp, int *offp, int proto)
459{
460	struct icmp *icp;
461	struct in_ifaddr *ia;
462	struct mbuf *m = *mp;
463	struct ip *ip = mtod(m, struct ip *);
464	struct sockaddr_in icmpsrc, icmpdst, icmpgw;
465	int hlen = *offp;
466	int icmplen = ntohs(ip->ip_len) - *offp;
467	int i, code;
468	int fibnum;
469
470	NET_EPOCH_ASSERT();
471
472	*mp = NULL;
473
474	/*
475	 * Locate icmp structure in mbuf, and check
476	 * that not corrupted and of at least minimum length.
477	 */
478#ifdef ICMPPRINTFS
479	if (icmpprintfs) {
480		char srcbuf[INET_ADDRSTRLEN];
481		char dstbuf[INET_ADDRSTRLEN];
482
483		printf("icmp_input from %s to %s, len %d\n",
484		    inet_ntoa_r(ip->ip_src, srcbuf),
485		    inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
486	}
487#endif
488	if (icmplen < ICMP_MINLEN) {
489		ICMPSTAT_INC(icps_tooshort);
490		goto freeit;
491	}
492	i = hlen + min(icmplen, ICMP_ADVLENMIN);
493	if (m->m_len < i && (m = m_pullup(m, i)) == NULL)  {
494		ICMPSTAT_INC(icps_tooshort);
495		return (IPPROTO_DONE);
496	}
497	ip = mtod(m, struct ip *);
498	m->m_len -= hlen;
499	m->m_data += hlen;
500	icp = mtod(m, struct icmp *);
501	if (in_cksum(m, icmplen)) {
502		ICMPSTAT_INC(icps_checksum);
503		goto freeit;
504	}
505	m->m_len += hlen;
506	m->m_data -= hlen;
507
508#ifdef ICMPPRINTFS
509	if (icmpprintfs)
510		printf("icmp_input, type %d code %d\n", icp->icmp_type,
511		    icp->icmp_code);
512#endif
513
514	/*
515	 * Message type specific processing.
516	 */
517	if (icp->icmp_type > ICMP_MAXTYPE)
518		goto raw;
519
520	/* Initialize */
521	bzero(&icmpsrc, sizeof(icmpsrc));
522	icmpsrc.sin_len = sizeof(struct sockaddr_in);
523	icmpsrc.sin_family = AF_INET;
524	bzero(&icmpdst, sizeof(icmpdst));
525	icmpdst.sin_len = sizeof(struct sockaddr_in);
526	icmpdst.sin_family = AF_INET;
527	bzero(&icmpgw, sizeof(icmpgw));
528	icmpgw.sin_len = sizeof(struct sockaddr_in);
529	icmpgw.sin_family = AF_INET;
530
531	ICMPSTAT_INC2(icps_inhist, icp->icmp_type);
532	code = icp->icmp_code;
533	switch (icp->icmp_type) {
534	case ICMP_UNREACH:
535		if (code > ICMP_UNREACH_PRECEDENCE_CUTOFF)
536			goto badcode;
537		else
538			goto deliver;
539
540	case ICMP_TIMXCEED:
541		if (code > ICMP_TIMXCEED_REASS)
542			goto badcode;
543		else
544			goto deliver;
545
546	case ICMP_PARAMPROB:
547		if (code > ICMP_PARAMPROB_LENGTH)
548			goto badcode;
549
550	deliver:
551		/*
552		 * Problem with datagram; advise higher level routines.
553		 */
554		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
555		    icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
556			ICMPSTAT_INC(icps_badlen);
557			goto freeit;
558		}
559		/* Discard ICMP's in response to multicast packets */
560		if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
561			goto badcode;
562		/* Filter out responses to INADDR_ANY, protocols ignore it. */
563		if (icp->icmp_ip.ip_dst.s_addr == INADDR_ANY ||
564		    icp->icmp_ip.ip_src.s_addr == INADDR_ANY)
565			goto freeit;
566#ifdef ICMPPRINTFS
567		if (icmpprintfs)
568			printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
569#endif
570		/*
571		 * XXX if the packet contains [IPv4 AH TCP], we can't make a
572		 * notification to TCP layer.
573		 */
574		i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
575		ip_stripoptions(m);
576		if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
577			/* This should actually not happen */
578			ICMPSTAT_INC(icps_tooshort);
579			return (IPPROTO_DONE);
580		}
581		ip = mtod(m, struct ip *);
582		icp = (struct icmp *)(ip + 1);
583		/*
584		 * The upper layer handler can rely on:
585		 * - The outer IP header has no options.
586		 * - The outer IP header, the ICMP header, the inner IP header,
587		 *   and the first n bytes of the inner payload are contiguous.
588		 *   n is at least 8, but might be larger based on
589		 *   ICMP_ADVLENPREF. See its definition in ip_icmp.h.
590		 */
591		if (ip_ctlprotox[icp->icmp_ip.ip_p] != NULL)
592			ip_ctlprotox[icp->icmp_ip.ip_p](icp);
593		break;
594
595	badcode:
596		ICMPSTAT_INC(icps_badcode);
597		break;
598
599	case ICMP_ECHO:
600		if (!V_icmpbmcastecho
601		    && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
602			ICMPSTAT_INC(icps_bmcastecho);
603			break;
604		}
605		if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
606			goto freeit;
607		icp->icmp_type = ICMP_ECHOREPLY;
608		goto reflect;
609
610	case ICMP_TSTAMP:
611		if (V_icmptstamprepl == 0)
612			break;
613		if (!V_icmpbmcastecho
614		    && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
615			ICMPSTAT_INC(icps_bmcasttstamp);
616			break;
617		}
618		if (icmplen < ICMP_TSLEN) {
619			ICMPSTAT_INC(icps_badlen);
620			break;
621		}
622		if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
623			goto freeit;
624		icp->icmp_type = ICMP_TSTAMPREPLY;
625		icp->icmp_rtime = iptime();
626		icp->icmp_ttime = icp->icmp_rtime;	/* bogus, do later! */
627		goto reflect;
628
629	case ICMP_MASKREQ:
630		if (V_icmpmaskrepl == 0)
631			break;
632		/*
633		 * We are not able to respond with all ones broadcast
634		 * unless we receive it over a point-to-point interface.
635		 */
636		if (icmplen < ICMP_MASKLEN)
637			break;
638		switch (ip->ip_dst.s_addr) {
639		case INADDR_BROADCAST:
640		case INADDR_ANY:
641			icmpdst.sin_addr = ip->ip_src;
642			break;
643
644		default:
645			icmpdst.sin_addr = ip->ip_dst;
646		}
647		ia = (struct in_ifaddr *)ifaof_ifpforaddr(
648			    (struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
649		if (ia == NULL)
650			break;
651		if (ia->ia_ifp == NULL)
652			break;
653		icp->icmp_type = ICMP_MASKREPLY;
654		if (V_icmpmaskfake == 0)
655			icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
656		else
657			icp->icmp_mask = V_icmpmaskfake;
658		if (ip->ip_src.s_addr == 0) {
659			if (ia->ia_ifp->if_flags & IFF_BROADCAST)
660			    ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
661			else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
662			    ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
663		}
664reflect:
665		ICMPSTAT_INC(icps_reflect);
666		ICMPSTAT_INC2(icps_outhist, icp->icmp_type);
667		icmp_reflect(m);
668		return (IPPROTO_DONE);
669
670	case ICMP_REDIRECT:
671		if (V_log_redirect) {
672			u_long src, dst, gw;
673
674			src = ntohl(ip->ip_src.s_addr);
675			dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
676			gw = ntohl(icp->icmp_gwaddr.s_addr);
677			printf("icmp redirect from %d.%d.%d.%d: "
678			       "%d.%d.%d.%d => %d.%d.%d.%d\n",
679			       (int)(src >> 24), (int)((src >> 16) & 0xff),
680			       (int)((src >> 8) & 0xff), (int)(src & 0xff),
681			       (int)(dst >> 24), (int)((dst >> 16) & 0xff),
682			       (int)((dst >> 8) & 0xff), (int)(dst & 0xff),
683			       (int)(gw >> 24), (int)((gw >> 16) & 0xff),
684			       (int)((gw >> 8) & 0xff), (int)(gw & 0xff));
685		}
686		/*
687		 * RFC1812 says we must ignore ICMP redirects if we
688		 * are acting as router.
689		 */
690		if (V_drop_redirect || V_ipforwarding)
691			break;
692		if (code > 3)
693			goto badcode;
694		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
695		    icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
696			ICMPSTAT_INC(icps_badlen);
697			break;
698		}
699		/*
700		 * Short circuit routing redirects to force
701		 * immediate change in the kernel's routing
702		 * tables.  The message is also handed to anyone
703		 * listening on a raw socket (e.g. the routing
704		 * daemon for use in updating its tables).
705		 */
706		icmpgw.sin_addr = ip->ip_src;
707		icmpdst.sin_addr = icp->icmp_gwaddr;
708#ifdef	ICMPPRINTFS
709		if (icmpprintfs) {
710			char dstbuf[INET_ADDRSTRLEN];
711			char gwbuf[INET_ADDRSTRLEN];
712
713			printf("redirect dst %s to %s\n",
714			       inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
715			       inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
716		}
717#endif
718		icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
719
720		/*
721		 * RFC 1122 says network (code 0,2) redirects SHOULD
722		 * be treated identically to the host redirects.
723		 * Given that, ignore network masks.
724		 */
725
726		/*
727		 * Variable values:
728		 * icmpsrc: route destination
729		 * icmpdst: route gateway
730		 * icmpgw: message source
731		 */
732
733		if (icmp_verify_redirect_gateway(&icmpgw, &icmpsrc, &icmpdst,
734		    M_GETFIB(m)) != 0) {
735			/* TODO: increment bad redirects here */
736			break;
737		}
738
739		for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
740			rib_add_redirect(fibnum, (struct sockaddr *)&icmpsrc,
741			    (struct sockaddr *)&icmpdst,
742			    (struct sockaddr *)&icmpgw, m->m_pkthdr.rcvif,
743			    RTF_GATEWAY, V_redirtimeout);
744		}
745		break;
746
747	/*
748	 * No kernel processing for the following;
749	 * just fall through to send to raw listener.
750	 */
751	case ICMP_ECHOREPLY:
752	case ICMP_ROUTERADVERT:
753	case ICMP_ROUTERSOLICIT:
754	case ICMP_TSTAMPREPLY:
755	case ICMP_IREQREPLY:
756	case ICMP_MASKREPLY:
757	case ICMP_SOURCEQUENCH:
758	default:
759		break;
760	}
761
762raw:
763	*mp = m;
764	rip_input(mp, offp, proto);
765	return (IPPROTO_DONE);
766
767freeit:
768	m_freem(m);
769	return (IPPROTO_DONE);
770}
771
772/*
773 * Reflect the ip packet back to the source
774 */
775static void
776icmp_reflect(struct mbuf *m)
777{
778	struct ip *ip = mtod(m, struct ip *);
779	struct ifaddr *ifa;
780	struct ifnet *ifp;
781	struct in_ifaddr *ia;
782	struct in_addr t;
783	struct nhop_object *nh;
784	struct mbuf *opts = NULL;
785	int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
786
787	NET_EPOCH_ASSERT();
788
789	if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
790	    (IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) && !V_ip_allow_net240) ||
791	    (IN_ZERONET(ntohl(ip->ip_src.s_addr)) && !V_ip_allow_net0) ) {
792		m_freem(m);	/* Bad return address */
793		ICMPSTAT_INC(icps_badaddr);
794		goto done;	/* Ip_output() will check for broadcast */
795	}
796
797	t = ip->ip_dst;
798	ip->ip_dst = ip->ip_src;
799
800	/*
801	 * Source selection for ICMP replies:
802	 *
803	 * If the incoming packet was addressed directly to one of our
804	 * own addresses, use dst as the src for the reply.
805	 */
806	CK_LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
807		if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
808			t = IA_SIN(ia)->sin_addr;
809			goto match;
810		}
811	}
812
813	/*
814	 * If the incoming packet was addressed to one of our broadcast
815	 * addresses, use the first non-broadcast address which corresponds
816	 * to the incoming interface.
817	 */
818	ifp = m->m_pkthdr.rcvif;
819	if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
820		CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
821			if (ifa->ifa_addr->sa_family != AF_INET)
822				continue;
823			ia = ifatoia(ifa);
824			if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
825			    t.s_addr) {
826				t = IA_SIN(ia)->sin_addr;
827				goto match;
828			}
829		}
830	}
831	/*
832	 * If the packet was transiting through us, use the address of
833	 * the interface the packet came through in.  If that interface
834	 * doesn't have a suitable IP address, the normal selection
835	 * criteria apply.
836	 */
837	if (V_icmp_rfi && ifp != NULL) {
838		CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
839			if (ifa->ifa_addr->sa_family != AF_INET)
840				continue;
841			ia = ifatoia(ifa);
842			t = IA_SIN(ia)->sin_addr;
843			goto match;
844		}
845	}
846	/*
847	 * If the incoming packet was not addressed directly to us, use
848	 * designated interface for icmp replies specified by sysctl
849	 * net.inet.icmp.reply_src (default not set). Otherwise continue
850	 * with normal source selection.
851	 */
852	if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
853		CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
854			if (ifa->ifa_addr->sa_family != AF_INET)
855				continue;
856			ia = ifatoia(ifa);
857			t = IA_SIN(ia)->sin_addr;
858			goto match;
859		}
860	}
861	/*
862	 * If the packet was transiting through us, use the address of
863	 * the interface that is the closest to the packet source.
864	 * When we don't have a route back to the packet source, stop here
865	 * and drop the packet.
866	 */
867	nh = fib4_lookup(M_GETFIB(m), ip->ip_dst, 0, NHR_NONE, 0);
868	if (nh == NULL) {
869		m_freem(m);
870		ICMPSTAT_INC(icps_noroute);
871		goto done;
872	}
873	t = IA_SIN(ifatoia(nh->nh_ifa))->sin_addr;
874match:
875#ifdef MAC
876	mac_netinet_icmp_replyinplace(m);
877#endif
878	ip->ip_src = t;
879	ip->ip_ttl = V_ip_defttl;
880
881	if (optlen > 0) {
882		u_char *cp;
883		int opt, cnt;
884		u_int len;
885
886		/*
887		 * Retrieve any source routing from the incoming packet;
888		 * add on any record-route or timestamp options.
889		 */
890		cp = (u_char *) (ip + 1);
891		if ((opts = ip_srcroute(m)) == NULL &&
892		    (opts = m_gethdr(M_NOWAIT, MT_DATA))) {
893			opts->m_len = sizeof(struct in_addr);
894			mtod(opts, struct in_addr *)->s_addr = 0;
895		}
896		if (opts) {
897#ifdef ICMPPRINTFS
898		    if (icmpprintfs)
899			    printf("icmp_reflect optlen %d rt %d => ",
900				optlen, opts->m_len);
901#endif
902		    for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
903			    opt = cp[IPOPT_OPTVAL];
904			    if (opt == IPOPT_EOL)
905				    break;
906			    if (opt == IPOPT_NOP)
907				    len = 1;
908			    else {
909				    if (cnt < IPOPT_OLEN + sizeof(*cp))
910					    break;
911				    len = cp[IPOPT_OLEN];
912				    if (len < IPOPT_OLEN + sizeof(*cp) ||
913				        len > cnt)
914					    break;
915			    }
916			    /*
917			     * Should check for overflow, but it "can't happen"
918			     */
919			    if (opt == IPOPT_RR || opt == IPOPT_TS ||
920				opt == IPOPT_SECURITY) {
921				    bcopy((caddr_t)cp,
922					mtod(opts, caddr_t) + opts->m_len, len);
923				    opts->m_len += len;
924			    }
925		    }
926		    /* Terminate & pad, if necessary */
927		    cnt = opts->m_len % 4;
928		    if (cnt) {
929			    for (; cnt < 4; cnt++) {
930				    *(mtod(opts, caddr_t) + opts->m_len) =
931					IPOPT_EOL;
932				    opts->m_len++;
933			    }
934		    }
935#ifdef ICMPPRINTFS
936		    if (icmpprintfs)
937			    printf("%d\n", opts->m_len);
938#endif
939		}
940		ip_stripoptions(m);
941	}
942	m_tag_delete_nonpersistent(m);
943	m->m_flags &= ~(M_BCAST|M_MCAST);
944	icmp_send(m, opts);
945done:
946	if (opts)
947		(void)m_free(opts);
948}
949
950/*
951 * Verifies if redirect message is valid, according to RFC 1122
952 *
953 * @src: sockaddr with address of redirect originator
954 * @dst: sockaddr with destination in question
955 * @gateway: new proposed gateway
956 *
957 * Returns 0 on success.
958 */
959static int
960icmp_verify_redirect_gateway(struct sockaddr_in *src, struct sockaddr_in *dst,
961    struct sockaddr_in *gateway, u_int fibnum)
962{
963	struct nhop_object *nh;
964	struct ifaddr *ifa;
965
966	NET_EPOCH_ASSERT();
967
968	/* Verify the gateway is directly reachable. */
969	if ((ifa = ifa_ifwithnet((struct sockaddr *)gateway, 0, fibnum))==NULL)
970		return (ENETUNREACH);
971
972	/* TODO: fib-aware. */
973	if (ifa_ifwithaddr_check((struct sockaddr *)gateway))
974		return (EHOSTUNREACH);
975
976	nh = fib4_lookup(fibnum, dst->sin_addr, 0, NHR_NONE, 0);
977	if (nh == NULL)
978		return (EINVAL);
979
980	/*
981	 * If the redirect isn't from our current router for this dst,
982	 * it's either old or wrong.  If it redirects us to ourselves,
983	 * we have a routing loop, perhaps as a result of an interface
984	 * going down recently.
985	 */
986	if (!sa_equal((struct sockaddr *)src, &nh->gw_sa))
987		return (EINVAL);
988	if (nh->nh_ifa != ifa && ifa->ifa_addr->sa_family != AF_LINK)
989		return (EINVAL);
990
991	/* If host route already exists, ignore redirect. */
992	if (nh->nh_flags & NHF_HOST)
993		return (EEXIST);
994
995	/* If the prefix is directly reachable, ignore redirect. */
996	if (!(nh->nh_flags & NHF_GATEWAY))
997		return (EEXIST);
998
999	return (0);
1000}
1001
1002/*
1003 * Send an icmp packet back to the ip level,
1004 * after supplying a checksum.
1005 */
1006static void
1007icmp_send(struct mbuf *m, struct mbuf *opts)
1008{
1009	struct ip *ip = mtod(m, struct ip *);
1010	int hlen;
1011	struct icmp *icp;
1012
1013	hlen = ip->ip_hl << 2;
1014	m->m_data += hlen;
1015	m->m_len -= hlen;
1016	icp = mtod(m, struct icmp *);
1017	icp->icmp_cksum = 0;
1018	icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen);
1019	m->m_data -= hlen;
1020	m->m_len += hlen;
1021	m->m_pkthdr.rcvif = (struct ifnet *)0;
1022#ifdef ICMPPRINTFS
1023	if (icmpprintfs) {
1024		char dstbuf[INET_ADDRSTRLEN];
1025		char srcbuf[INET_ADDRSTRLEN];
1026
1027		printf("icmp_send dst %s src %s\n",
1028		    inet_ntoa_r(ip->ip_dst, dstbuf),
1029		    inet_ntoa_r(ip->ip_src, srcbuf));
1030	}
1031#endif
1032	(void) ip_output(m, opts, NULL, 0, NULL, NULL);
1033}
1034
1035/*
1036 * Return milliseconds since 00:00 UTC in network format.
1037 */
1038uint32_t
1039iptime(void)
1040{
1041	struct timeval atv;
1042	u_long t;
1043
1044	getmicrotime(&atv);
1045	t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
1046	return (htonl(t));
1047}
1048
1049/*
1050 * Return the next larger or smaller MTU plateau (table from RFC 1191)
1051 * given current value MTU.  If DIR is less than zero, a larger plateau
1052 * is returned; otherwise, a smaller value is returned.
1053 */
1054int
1055ip_next_mtu(int mtu, int dir)
1056{
1057	static int mtutab[] = {
1058		65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508,
1059		296, 68, 0
1060	};
1061	int i, size;
1062
1063	size = (sizeof mtutab) / (sizeof mtutab[0]);
1064	if (dir >= 0) {
1065		for (i = 0; i < size; i++)
1066			if (mtu > mtutab[i])
1067				return mtutab[i];
1068	} else {
1069		for (i = size - 1; i >= 0; i--)
1070			if (mtu < mtutab[i])
1071				return mtutab[i];
1072		if (mtu == mtutab[0])
1073			return mtutab[0];
1074	}
1075	return 0;
1076}
1077#endif /* INET */
1078
1079/*
1080 * badport_bandlim() - check for ICMP bandwidth limit
1081 *
1082 *	Return 0 if it is ok to send an ICMP error response, -1 if we have
1083 *	hit our bandwidth limit and it is not ok.
1084 *
1085 *	If icmplim is <= 0, the feature is disabled and 0 is returned.
1086 *
1087 *	For now we separate the TCP and UDP subsystems w/ different 'which'
1088 *	values.  We may eventually remove this separation (and simplify the
1089 *	code further).
1090 *
1091 *	Note that the printing of the error message is delayed so we can
1092 *	properly print the icmp error rate that the system was trying to do
1093 *	(i.e. 22000/100 pps, etc...).  This can cause long delays in printing
1094 *	the 'final' error, but it doesn't make sense to solve the printing
1095 *	delay with more complex code.
1096 */
1097VNET_DEFINE_STATIC(struct counter_rate, icmp_rates[BANDLIM_MAX]);
1098#define	V_icmp_rates	VNET(icmp_rates)
1099
1100static const char *icmp_rate_descrs[BANDLIM_MAX] = {
1101	[BANDLIM_ICMP_UNREACH] = "icmp unreach",
1102	[BANDLIM_ICMP_ECHO] = "icmp ping",
1103	[BANDLIM_ICMP_TSTAMP] = "icmp tstamp",
1104	[BANDLIM_RST_CLOSEDPORT] = "closed port RST",
1105	[BANDLIM_RST_OPENPORT] = "open port RST",
1106	[BANDLIM_ICMP6_UNREACH] = "icmp6 unreach",
1107	[BANDLIM_SCTP_OOTB] = "sctp ootb",
1108};
1109
1110static void
1111icmplim_new_jitter(void)
1112{
1113	/*
1114	 * Adjust limit +/- to jitter the measurement to deny a side-channel
1115	 * port scan as in https://dl.acm.org/doi/10.1145/3372297.3417280
1116	 */
1117	if (V_icmplim_jitter > 0)
1118		V_icmplim_curr_jitter =
1119		    arc4random_uniform(V_icmplim_jitter * 2 + 1) -
1120		    V_icmplim_jitter;
1121}
1122
1123static int
1124sysctl_icmplim_and_jitter(SYSCTL_HANDLER_ARGS)
1125{
1126	uint32_t new;
1127	int error;
1128	bool lim;
1129
1130	MPASS(oidp->oid_arg1 == &VNET_NAME(icmplim) ||
1131	    oidp->oid_arg1 == &VNET_NAME(icmplim_jitter));
1132
1133	lim = (oidp->oid_arg1 == &VNET_NAME(icmplim));
1134	new = lim ? V_icmplim : V_icmplim_jitter;
1135	error = sysctl_handle_int(oidp, &new, 0, req);
1136	if (error == 0 && req->newptr) {
1137		if (lim) {
1138			if (new != 0 && new <= V_icmplim_jitter)
1139				error = EINVAL;
1140			else
1141				V_icmplim = new;
1142		} else {
1143			if (new >= V_icmplim)
1144				error = EINVAL;
1145			else {
1146				V_icmplim_jitter = new;
1147				icmplim_new_jitter();
1148			}
1149		}
1150	}
1151	MPASS(V_icmplim + V_icmplim_curr_jitter >= 0);
1152
1153	return (error);
1154}
1155
1156static void
1157icmp_bandlimit_init(void)
1158{
1159
1160	for (int i = 0; i < BANDLIM_MAX; i++) {
1161		V_icmp_rates[i].cr_rate = counter_u64_alloc(M_WAITOK);
1162		V_icmp_rates[i].cr_ticks = ticks;
1163	}
1164	icmplim_new_jitter();
1165}
1166VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY,
1167    icmp_bandlimit_init, NULL);
1168
1169#ifdef VIMAGE
1170static void
1171icmp_bandlimit_uninit(void)
1172{
1173
1174	for (int i = 0; i < BANDLIM_MAX; i++)
1175		counter_u64_free(V_icmp_rates[i].cr_rate);
1176}
1177VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD,
1178    icmp_bandlimit_uninit, NULL);
1179#endif
1180
1181int
1182badport_bandlim(int which)
1183{
1184	int64_t pps;
1185
1186	if (V_icmplim == 0 || which == BANDLIM_UNLIMITED)
1187		return (0);
1188
1189	KASSERT(which >= 0 && which < BANDLIM_MAX,
1190	    ("%s: which %d", __func__, which));
1191
1192	pps = counter_ratecheck(&V_icmp_rates[which], V_icmplim +
1193	    V_icmplim_curr_jitter);
1194	if (pps > 0) {
1195		if (V_icmplim_output)
1196			log(LOG_NOTICE,
1197			    "Limiting %s response from %jd to %d packets/sec\n",
1198			    icmp_rate_descrs[which], (intmax_t )pps,
1199			    V_icmplim + V_icmplim_curr_jitter);
1200		icmplim_new_jitter();
1201	}
1202	if (pps == -1)
1203		return (-1);
1204	return (0);
1205}
1206