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/* $OpenBSD: ip_icmp.c,v 1.192 2023/09/16 09:33:27 mpi Exp $ */
/* $NetBSD: ip_icmp.c,v 1.19 1996/02/13 23:42:22 christos Exp $ */
/*
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)COPYRIGHT 1.1 (NRL) 17 January 1995
*
* NRL grants permission for redistribution and use in source and binary
* forms, with or without modification, of the software and documentation
* created at NRL provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgements:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* This product includes software developed at the Information
* Technology Division, US Naval Research Laboratory.
* 4. Neither the name of the NRL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the US Naval
* Research Laboratory (NRL).
*/
#include "carp.h"
#include "pf.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_var.h>
#include <netinet/icmp_var.h>
#if NCARP > 0
#include <net/if_types.h>
#include <netinet/ip_carp.h>
#endif
#if NPF > 0
#include <net/pfvar.h>
#endif
/*
* ICMP routines: error generation, receive packet processing, and
* routines to turnaround packets back to the originator, and
* host table maintenance routines.
*/
#ifdef ICMPPRINTFS
int icmpprintfs = 0; /* Settable from ddb */
#endif
/* values controllable via sysctl */
int icmpmaskrepl = 0;
int icmpbmcastecho = 0;
int icmptstamprepl = 1;
int icmperrppslim = 100;
int icmp_rediraccept = 0;
int icmp_redirtimeout = 10 * 60;
static int icmperrpps_count = 0;
static struct timeval icmperrppslim_last;
struct rttimer_queue ip_mtudisc_timeout_q;
struct rttimer_queue icmp_redirect_timeout_q;
struct cpumem *icmpcounters;
const struct sysctl_bounded_args icmpctl_vars[] = {
{ ICMPCTL_MASKREPL, &icmpmaskrepl, 0, 1 },
{ ICMPCTL_BMCASTECHO, &icmpbmcastecho, 0, 1 },
{ ICMPCTL_ERRPPSLIMIT, &icmperrppslim, -1, INT_MAX },
{ ICMPCTL_REDIRACCEPT, &icmp_rediraccept, 0, 1 },
{ ICMPCTL_TSTAMPREPL, &icmptstamprepl, 0, 1 },
};
void icmp_mtudisc_timeout(struct rtentry *, u_int);
int icmp_ratelimit(const struct in_addr *, const int, const int);
int icmp_input_if(struct ifnet *, struct mbuf **, int *, int, int);
int icmp_sysctl_icmpstat(void *, size_t *, void *);
void
icmp_init(void)
{
rt_timer_queue_init(&ip_mtudisc_timeout_q, ip_mtudisc_timeout,
&icmp_mtudisc_timeout);
rt_timer_queue_init(&icmp_redirect_timeout_q, icmp_redirtimeout,
NULL);
icmpcounters = counters_alloc(icps_ncounters);
}
struct mbuf *
icmp_do_error(struct mbuf *n, int type, int code, u_int32_t dest, int destmtu)
{
struct ip *oip = mtod(n, struct ip *), *nip;
unsigned oiplen = oip->ip_hl << 2;
struct icmp *icp;
struct mbuf *m;
unsigned icmplen, mblen;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_error(%x, %d, %d)\n", oip, type, code);
#endif
if (type != ICMP_REDIRECT)
icmpstat_inc(icps_error);
/*
* Don't send error if not the first fragment of message.
* Don't error if the old packet protocol was ICMP
* error message, only known informational types.
*/
if (oip->ip_off & htons(IP_OFFMASK))
goto freeit;
if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
n->m_len >= oiplen + ICMP_MINLEN &&
!ICMP_INFOTYPE(((struct icmp *)
((caddr_t)oip + oiplen))->icmp_type)) {
icmpstat_inc(icps_oldicmp);
goto freeit;
}
/* Don't send error in response to a multicast or broadcast packet */
if (n->m_flags & (M_BCAST|M_MCAST))
goto freeit;
/*
* First, do a rate limitation check.
*/
if (icmp_ratelimit(&oip->ip_src, type, code)) {
icmpstat_inc(icps_toofreq);
goto freeit;
}
/*
* Now, formulate icmp message
*/
icmplen = oiplen + min(8, ntohs(oip->ip_len));
/*
* Defend against mbuf chains shorter than oip->ip_len:
*/
mblen = 0;
for (m = n; m && (mblen < icmplen); m = m->m_next)
mblen += m->m_len;
icmplen = min(mblen, icmplen);
/*
* As we are not required to return everything we have,
* we return whatever we can return at ease.
*
* Note that ICMP datagrams longer than 576 octets are out of spec
* according to RFC1812;
*/
KASSERT(ICMP_MINLEN + sizeof (struct ip) <= MCLBYTES);
if (sizeof (struct ip) + icmplen + ICMP_MINLEN > MCLBYTES)
icmplen = MCLBYTES - ICMP_MINLEN - sizeof (struct ip);
m = m_gethdr(M_DONTWAIT, MT_HEADER);
if (m && ((sizeof (struct ip) + icmplen + ICMP_MINLEN +
sizeof(long) - 1) &~ (sizeof(long) - 1)) > MHLEN) {
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_freem(m);
m = NULL;
}
}
if (m == NULL)
goto freeit;
/* keep in same rtable and preserve other pkthdr bits */
m->m_pkthdr.ph_rtableid = n->m_pkthdr.ph_rtableid;
m->m_pkthdr.ph_ifidx = n->m_pkthdr.ph_ifidx;
/* move PF_GENERATED to new packet, if existent XXX preserve more? */
if (n->m_pkthdr.pf.flags & PF_TAG_GENERATED)
m->m_pkthdr.pf.flags |= PF_TAG_GENERATED;
m->m_pkthdr.len = m->m_len = icmplen + ICMP_MINLEN;
m_align(m, m->m_len);
icp = mtod(m, struct icmp *);
if ((u_int)type > ICMP_MAXTYPE)
panic("icmp_error");
icmpstat_inc(icps_outhist + type);
icp->icmp_type = type;
if (type == ICMP_REDIRECT)
icp->icmp_gwaddr.s_addr = dest;
else {
icp->icmp_void = 0;
/*
* The following assignments assume an overlay with the
* zeroed icmp_void field.
*/
if (type == ICMP_PARAMPROB) {
icp->icmp_pptr = code;
code = 0;
} else if (type == ICMP_UNREACH &&
code == ICMP_UNREACH_NEEDFRAG && destmtu)
icp->icmp_nextmtu = htons(destmtu);
}
icp->icmp_code = code;
m_copydata(n, 0, icmplen, &icp->icmp_ip);
/*
* Now, copy old ip header (without options)
* in front of icmp message.
*/
m = m_prepend(m, sizeof(struct ip), M_DONTWAIT);
if (m == NULL)
goto freeit;
nip = mtod(m, struct ip *);
/* ip_v set in ip_output */
nip->ip_hl = sizeof(struct ip) >> 2;
nip->ip_tos = 0;
nip->ip_len = htons(m->m_len);
/* ip_id set in ip_output */
nip->ip_off = 0;
/* ip_ttl set in icmp_reflect */
nip->ip_p = IPPROTO_ICMP;
nip->ip_src = oip->ip_src;
nip->ip_dst = oip->ip_dst;
m_freem(n);
return (m);
freeit:
m_freem(n);
return (NULL);
}
/*
* Generate an error packet of type error
* in response to bad packet ip.
*
* The ip packet inside has ip_off and ip_len in host byte order.
*/
void
icmp_error(struct mbuf *n, int type, int code, u_int32_t dest, int destmtu)
{
struct mbuf *m;
m = icmp_do_error(n, type, code, dest, destmtu);
if (m != NULL)
if (!icmp_reflect(m, NULL, NULL))
icmp_send(m, NULL);
}
/*
* Process a received ICMP message.
*/
int
icmp_input(struct mbuf **mp, int *offp, int proto, int af)
{
struct ifnet *ifp;
ifp = if_get((*mp)->m_pkthdr.ph_ifidx);
if (ifp == NULL) {
m_freemp(mp);
return IPPROTO_DONE;
}
proto = icmp_input_if(ifp, mp, offp, proto, af);
if_put(ifp);
return proto;
}
int
icmp_input_if(struct ifnet *ifp, struct mbuf **mp, int *offp, int proto, int af)
{
struct mbuf *m = *mp;
int hlen = *offp;
struct icmp *icp;
struct ip *ip = mtod(m, struct ip *);
struct sockaddr_in sin;
int icmplen, i, code;
struct in_ifaddr *ia;
void (*ctlfunc)(int, struct sockaddr *, u_int, void *);
struct mbuf *opts;
/*
* Locate icmp structure in mbuf, and check
* that not corrupted and of at least minimum length.
*/
icmplen = ntohs(ip->ip_len) - hlen;
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char dst[INET_ADDRSTRLEN], src[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &ip->ip_dst, dst, sizeof(dst));
inet_ntop(AF_INET, &ip->ip_src, src, sizeof(src));
printf("icmp_input from %s to %s, len %d\n", src, dst, icmplen);
}
#endif
if (icmplen < ICMP_MINLEN) {
icmpstat_inc(icps_tooshort);
goto freeit;
}
i = hlen + min(icmplen, ICMP_ADVLENMAX);
if ((m = *mp = m_pullup(m, i)) == NULL) {
icmpstat_inc(icps_tooshort);
return IPPROTO_DONE;
}
ip = mtod(m, struct ip *);
if (in4_cksum(m, 0, hlen, icmplen)) {
icmpstat_inc(icps_checksum);
goto freeit;
}
icp = (struct icmp *)(mtod(m, caddr_t) + hlen);
#ifdef ICMPPRINTFS
/*
* Message type specific processing.
*/
if (icmpprintfs)
printf("icmp_input, type %d code %d\n", icp->icmp_type,
icp->icmp_code);
#endif
if (icp->icmp_type > ICMP_MAXTYPE)
goto raw;
#if NPF > 0
if (m->m_pkthdr.pf.flags & PF_TAG_DIVERTED) {
switch (icp->icmp_type) {
/*
* As pf_icmp_mapping() considers redirects belonging to a
* diverted connection, we must include it here.
*/
case ICMP_REDIRECT:
/* FALLTHROUGH */
/*
* These ICMP types map to other connections. They must be
* delivered to pr_ctlinput() also for diverted connections.
*/
case ICMP_UNREACH:
case ICMP_TIMXCEED:
case ICMP_PARAMPROB:
case ICMP_SOURCEQUENCH:
/*
* Do not use the divert-to property of the TCP or UDP
* rule when doing the PCB lookup for the raw socket.
*/
m->m_pkthdr.pf.flags &=~ PF_TAG_DIVERTED;
break;
default:
goto raw;
}
}
#endif /* NPF */
icmpstat_inc(icps_inhist + icp->icmp_type);
code = icp->icmp_code;
switch (icp->icmp_type) {
case ICMP_UNREACH:
switch (code) {
case ICMP_UNREACH_NET:
case ICMP_UNREACH_HOST:
case ICMP_UNREACH_PROTOCOL:
case ICMP_UNREACH_PORT:
case ICMP_UNREACH_SRCFAIL:
code += PRC_UNREACH_NET;
break;
case ICMP_UNREACH_NEEDFRAG:
code = PRC_MSGSIZE;
break;
case ICMP_UNREACH_NET_UNKNOWN:
case ICMP_UNREACH_NET_PROHIB:
case ICMP_UNREACH_TOSNET:
code = PRC_UNREACH_NET;
break;
case ICMP_UNREACH_HOST_UNKNOWN:
case ICMP_UNREACH_ISOLATED:
case ICMP_UNREACH_HOST_PROHIB:
case ICMP_UNREACH_TOSHOST:
case ICMP_UNREACH_FILTER_PROHIB:
case ICMP_UNREACH_HOST_PRECEDENCE:
case ICMP_UNREACH_PRECEDENCE_CUTOFF:
code = PRC_UNREACH_HOST;
break;
default:
goto badcode;
}
goto deliver;
case ICMP_TIMXCEED:
if (code > 1)
goto badcode;
code += PRC_TIMXCEED_INTRANS;
goto deliver;
case ICMP_PARAMPROB:
if (code > 1)
goto badcode;
code = PRC_PARAMPROB;
goto deliver;
case ICMP_SOURCEQUENCH:
if (code)
goto badcode;
code = PRC_QUENCH;
deliver:
/*
* Problem with datagram; advise higher level routines.
*/
if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
icmpstat_inc(icps_badlen);
goto freeit;
}
if (IN_MULTICAST(icp->icmp_ip.ip_dst.s_addr))
goto badcode;
#ifdef INET6
/* Get more contiguous data for a v6 in v4 ICMP message. */
if (icp->icmp_ip.ip_p == IPPROTO_IPV6) {
if (icmplen < ICMP_V6ADVLENMIN ||
icmplen < ICMP_V6ADVLEN(icp)) {
icmpstat_inc(icps_badlen);
goto freeit;
}
}
#endif /* INET6 */
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
#endif
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_len = sizeof(struct sockaddr_in);
sin.sin_addr = icp->icmp_ip.ip_dst;
#if NCARP > 0
if (carp_lsdrop(ifp, m, AF_INET, &sin.sin_addr.s_addr,
&ip->ip_dst.s_addr, 1))
goto freeit;
#endif
/*
* XXX if the packet contains [IPv4 AH TCP], we can't make a
* notification to TCP layer.
*/
ctlfunc = inetsw[ip_protox[icp->icmp_ip.ip_p]].pr_ctlinput;
if (ctlfunc)
(*ctlfunc)(code, sintosa(&sin), m->m_pkthdr.ph_rtableid,
&icp->icmp_ip);
break;
badcode:
icmpstat_inc(icps_badcode);
break;
case ICMP_ECHO:
if (!icmpbmcastecho &&
(m->m_flags & (M_MCAST | M_BCAST)) != 0) {
icmpstat_inc(icps_bmcastecho);
break;
}
icp->icmp_type = ICMP_ECHOREPLY;
goto reflect;
case ICMP_TSTAMP:
if (icmptstamprepl == 0)
break;
if (!icmpbmcastecho &&
(m->m_flags & (M_MCAST | M_BCAST)) != 0) {
icmpstat_inc(icps_bmcastecho);
break;
}
if (icmplen < ICMP_TSLEN) {
icmpstat_inc(icps_badlen);
break;
}
icp->icmp_type = ICMP_TSTAMPREPLY;
icp->icmp_rtime = iptime();
icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
goto reflect;
case ICMP_MASKREQ:
if (icmpmaskrepl == 0)
break;
if (icmplen < ICMP_MASKLEN) {
icmpstat_inc(icps_badlen);
break;
}
/*
* We are not able to respond with all ones broadcast
* unless we receive it over a point-to-point interface.
*/
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_len = sizeof(struct sockaddr_in);
if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
ip->ip_dst.s_addr == INADDR_ANY)
sin.sin_addr = ip->ip_src;
else
sin.sin_addr = ip->ip_dst;
if (ifp == NULL)
break;
ia = ifatoia(ifaof_ifpforaddr(sintosa(&sin), ifp));
if (ia == NULL)
break;
icp->icmp_type = ICMP_MASKREPLY;
icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
if (ip->ip_src.s_addr == 0) {
if (ifp->if_flags & IFF_BROADCAST) {
if (ia->ia_broadaddr.sin_addr.s_addr)
ip->ip_src = ia->ia_broadaddr.sin_addr;
else
ip->ip_src.s_addr = INADDR_BROADCAST;
}
else if (ifp->if_flags & IFF_POINTOPOINT)
ip->ip_src = ia->ia_dstaddr.sin_addr;
}
reflect:
#if NCARP > 0
if (carp_lsdrop(ifp, m, AF_INET, &ip->ip_src.s_addr,
&ip->ip_dst.s_addr, 1))
goto freeit;
#endif
icmpstat_inc(icps_reflect);
icmpstat_inc(icps_outhist + icp->icmp_type);
if (!icmp_reflect(m, &opts, NULL)) {
icmp_send(m, opts);
m_free(opts);
}
return IPPROTO_DONE;
case ICMP_REDIRECT:
{
struct sockaddr_in sdst;
struct sockaddr_in sgw;
struct sockaddr_in ssrc;
struct rtentry *newrt = NULL;
if (icmp_rediraccept == 0 || ipforwarding == 1)
goto freeit;
if (code > 3)
goto badcode;
if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
icp->icmp_ip.ip_hl < (sizeof(struct ip) >> 2)) {
icmpstat_inc(icps_badlen);
break;
}
/*
* Short circuit routing redirects to force
* immediate change in the kernel's routing
* tables. The message is also handed to anyone
* listening on a raw socket (e.g. the routing
* daemon for use in updating its tables).
*/
memset(&sdst, 0, sizeof(sdst));
memset(&sgw, 0, sizeof(sgw));
memset(&ssrc, 0, sizeof(ssrc));
sdst.sin_family = sgw.sin_family = ssrc.sin_family = AF_INET;
sdst.sin_len = sgw.sin_len = ssrc.sin_len = sizeof(sdst);
memcpy(&sdst.sin_addr, &icp->icmp_ip.ip_dst,
sizeof(sdst.sin_addr));
memcpy(&sgw.sin_addr, &icp->icmp_gwaddr,
sizeof(sgw.sin_addr));
memcpy(&ssrc.sin_addr, &ip->ip_src,
sizeof(ssrc.sin_addr));
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char gw[INET_ADDRSTRLEN], dst[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &icp->icmp_gwaddr, gw, sizeof(gw));
inet_ntop(AF_INET, &icp->icmp_ip.ip_dst,
dst, sizeof(dst));
printf("redirect dst %s to %s\n", dst, gw);
}
#endif
#if NCARP > 0
if (carp_lsdrop(ifp, m, AF_INET, &sdst.sin_addr.s_addr,
&ip->ip_dst.s_addr, 1))
goto freeit;
#endif
rtredirect(sintosa(&sdst), sintosa(&sgw),
sintosa(&ssrc), &newrt, m->m_pkthdr.ph_rtableid);
if (newrt != NULL && icmp_redirtimeout > 0) {
rt_timer_add(newrt, &icmp_redirect_timeout_q,
m->m_pkthdr.ph_rtableid);
}
rtfree(newrt);
pfctlinput(PRC_REDIRECT_HOST, sintosa(&sdst));
break;
}
/*
* No kernel processing for the following;
* just fall through to send to raw listener.
*/
case ICMP_ECHOREPLY:
case ICMP_ROUTERADVERT:
case ICMP_ROUTERSOLICIT:
case ICMP_TSTAMPREPLY:
case ICMP_IREQREPLY:
case ICMP_MASKREPLY:
case ICMP_TRACEROUTE:
case ICMP_DATACONVERR:
case ICMP_MOBILE_REDIRECT:
case ICMP_IPV6_WHEREAREYOU:
case ICMP_IPV6_IAMHERE:
case ICMP_MOBILE_REGREQUEST:
case ICMP_MOBILE_REGREPLY:
case ICMP_PHOTURIS:
default:
break;
}
raw:
return rip_input(mp, offp, proto, af);
freeit:
m_freem(m);
return IPPROTO_DONE;
}
/*
* Reflect the ip packet back to the source
*/
int
icmp_reflect(struct mbuf *m, struct mbuf **op, struct in_ifaddr *ia)
{
struct ip *ip = mtod(m, struct ip *);
struct mbuf *opts = NULL;
struct sockaddr_in sin;
struct rtentry *rt = NULL;
int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
u_int rtableid;
u_int8_t pfflags;
if (!in_canforward(ip->ip_src) &&
((ip->ip_src.s_addr & IN_CLASSA_NET) !=
htonl(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
m_freem(m); /* Bad return address */
return (EHOSTUNREACH);
}
if (m->m_pkthdr.ph_loopcnt++ >= M_MAXLOOP) {
m_freem(m);
return (ELOOP);
}
rtableid = m->m_pkthdr.ph_rtableid;
pfflags = m->m_pkthdr.pf.flags;
m_resethdr(m);
m->m_pkthdr.ph_rtableid = rtableid;
m->m_pkthdr.pf.flags = pfflags & PF_TAG_GENERATED;
/*
* If the incoming packet was addressed directly to us,
* use dst as the src for the reply. For broadcast, use
* the address which corresponds to the incoming interface.
*/
if (ia == NULL) {
memset(&sin, 0, sizeof(sin));
sin.sin_len = sizeof(sin);
sin.sin_family = AF_INET;
sin.sin_addr = ip->ip_dst;
rt = rtalloc(sintosa(&sin), 0, rtableid);
if (rtisvalid(rt) &&
ISSET(rt->rt_flags, RTF_LOCAL|RTF_BROADCAST))
ia = ifatoia(rt->rt_ifa);
}
/*
* The following happens if the packet was not addressed to us.
* Use the new source address and do a route lookup. If it fails
* drop the packet as there is no path to the host.
*/
if (ia == NULL) {
rtfree(rt);
memset(&sin, 0, sizeof(sin));
sin.sin_len = sizeof(sin);
sin.sin_family = AF_INET;
sin.sin_addr = ip->ip_src;
/* keep packet in the original virtual instance */
rt = rtalloc(sintosa(&sin), RT_RESOLVE, rtableid);
if (rt == NULL) {
ipstat_inc(ips_noroute);
m_freem(m);
return (EHOSTUNREACH);
}
ia = ifatoia(rt->rt_ifa);
}
ip->ip_dst = ip->ip_src;
ip->ip_ttl = MAXTTL;
/* It is safe to dereference ``ia'' iff ``rt'' is valid. */
ip->ip_src = ia->ia_addr.sin_addr;
rtfree(rt);
if (optlen > 0) {
u_char *cp;
int opt, cnt;
u_int len;
/*
* Retrieve any source routing from the incoming packet;
* add on any record-route or timestamp options.
*/
cp = (u_char *) (ip + 1);
if (op && (opts = ip_srcroute(m)) == NULL &&
(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
opts->m_len = sizeof(struct in_addr);
mtod(opts, struct in_addr *)->s_addr = 0;
}
if (op && opts) {
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_reflect optlen %d rt %d => ",
optlen, opts->m_len);
#endif
for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
opt = cp[IPOPT_OPTVAL];
if (opt == IPOPT_EOL)
break;
if (opt == IPOPT_NOP)
len = 1;
else {
if (cnt < IPOPT_OLEN + sizeof(*cp))
break;
len = cp[IPOPT_OLEN];
if (len < IPOPT_OLEN + sizeof(*cp) ||
len > cnt)
break;
}
/*
* Should check for overflow, but it
* "can't happen"
*/
if (opt == IPOPT_RR || opt == IPOPT_TS ||
opt == IPOPT_SECURITY) {
memcpy(mtod(opts, caddr_t) +
opts->m_len, cp, len);
opts->m_len += len;
}
}
/* Terminate & pad, if necessary */
if ((cnt = opts->m_len % 4) != 0)
for (; cnt < 4; cnt++) {
*(mtod(opts, caddr_t) + opts->m_len) =
IPOPT_EOL;
opts->m_len++;
}
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("%d\n", opts->m_len);
#endif
}
ip_stripoptions(m);
}
m->m_flags &= ~(M_BCAST|M_MCAST);
if (op)
*op = opts;
return (0);
}
/*
* Send an icmp packet back to the ip level
*/
void
icmp_send(struct mbuf *m, struct mbuf *opts)
{
struct ip *ip = mtod(m, struct ip *);
int hlen;
struct icmp *icp;
hlen = ip->ip_hl << 2;
icp = (struct icmp *)(mtod(m, caddr_t) + hlen);
icp->icmp_cksum = 0;
m->m_pkthdr.csum_flags = M_ICMP_CSUM_OUT;
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char dst[INET_ADDRSTRLEN], src[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &ip->ip_dst, dst, sizeof(dst));
inet_ntop(AF_INET, &ip->ip_src, src, sizeof(src));
printf("icmp_send dst %s src %s\n", dst, src);
}
#endif
/*
* ip_send() cannot handle IP options properly. So in case we have
* options fill out the IP header here and use ip_send_raw() instead.
*/
if (opts != NULL) {
m = ip_insertoptions(m, opts, &hlen);
ip = mtod(m, struct ip *);
ip->ip_hl = (hlen >> 2);
ip->ip_v = IPVERSION;
ip->ip_off &= htons(IP_DF);
ip->ip_id = htons(ip_randomid());
ipstat_inc(ips_localout);
ip_send_raw(m);
} else
ip_send(m);
}
u_int32_t
iptime(void)
{
struct timeval atv;
u_long t;
microtime(&atv);
t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
return (htonl(t));
}
int
icmp_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
size_t newlen)
{
int error;
/* All sysctl names at this level are terminal. */
if (namelen != 1)
return (ENOTDIR);
switch (name[0]) {
case ICMPCTL_REDIRTIMEOUT:
NET_LOCK();
error = sysctl_int_bounded(oldp, oldlenp, newp, newlen,
&icmp_redirtimeout, 0, INT_MAX);
rt_timer_queue_change(&icmp_redirect_timeout_q,
icmp_redirtimeout);
NET_UNLOCK();
break;
case ICMPCTL_STATS:
error = icmp_sysctl_icmpstat(oldp, oldlenp, newp);
break;
default:
NET_LOCK();
error = sysctl_bounded_arr(icmpctl_vars, nitems(icmpctl_vars),
name, namelen, oldp, oldlenp, newp, newlen);
NET_UNLOCK();
break;
}
return (error);
}
int
icmp_sysctl_icmpstat(void *oldp, size_t *oldlenp, void *newp)
{
uint64_t counters[icps_ncounters];
struct icmpstat icmpstat;
u_long *words = (u_long *)&icmpstat;
int i;
CTASSERT(sizeof(icmpstat) == (nitems(counters) * sizeof(u_long)));
memset(&icmpstat, 0, sizeof icmpstat);
counters_read(icmpcounters, counters, nitems(counters), NULL);
for (i = 0; i < nitems(counters); i++)
words[i] = (u_long)counters[i];
return (sysctl_rdstruct(oldp, oldlenp, newp,
&icmpstat, sizeof(icmpstat)));
}
struct rtentry *
icmp_mtudisc_clone(struct in_addr dst, u_int rtableid, int ipsec)
{
struct sockaddr_in sin;
struct rtentry *rt;
int error;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_len = sizeof(sin);
sin.sin_addr = dst;
rt = rtalloc(sintosa(&sin), RT_RESOLVE, rtableid);
/* Check if the route is actually usable */
if (!rtisvalid(rt))
goto bad;
/* IPsec needs the route only for PMTU, it can use reject for that */
if (!ipsec && (rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)))
goto bad;
/*
* No PMTU for local routes and permanent neighbors,
* ARP and NDP use the same expire timer as the route.
*/
if (ISSET(rt->rt_flags, RTF_LOCAL) ||
(ISSET(rt->rt_flags, RTF_LLINFO) && rt->rt_expire == 0))
goto bad;
/* If we didn't get a host route, allocate one */
if ((rt->rt_flags & RTF_HOST) == 0) {
struct rtentry *nrt;
struct rt_addrinfo info;
struct sockaddr_rtlabel sa_rl;
memset(&info, 0, sizeof(info));
info.rti_ifa = rt->rt_ifa;
info.rti_flags = RTF_GATEWAY | RTF_HOST | RTF_DYNAMIC;
info.rti_info[RTAX_DST] = sintosa(&sin);
info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
info.rti_info[RTAX_LABEL] =
rtlabel_id2sa(rt->rt_labelid, &sa_rl);
error = rtrequest(RTM_ADD, &info, rt->rt_priority, &nrt,
rtableid);
if (error)
goto bad;
nrt->rt_rmx = rt->rt_rmx;
rtfree(rt);
rt = nrt;
rtm_send(rt, RTM_ADD, 0, rtableid);
}
error = rt_timer_add(rt, &ip_mtudisc_timeout_q, rtableid);
if (error)
goto bad;
return (rt);
bad:
rtfree(rt);
return (NULL);
}
/* Table of common MTUs: */
static const u_short mtu_table[] = {
65535, 65280, 32000, 17914, 9180, 8166,
4352, 2002, 1492, 1006, 508, 296, 68, 0
};
void
icmp_mtudisc(struct icmp *icp, u_int rtableid)
{
struct rtentry *rt;
struct ifnet *ifp;
u_long mtu = ntohs(icp->icmp_nextmtu); /* Why a long? IPv6 */
rt = icmp_mtudisc_clone(icp->icmp_ip.ip_dst, rtableid, 0);
if (rt == NULL)
return;
ifp = if_get(rt->rt_ifidx);
if (ifp == NULL) {
rtfree(rt);
return;
}
if (mtu == 0) {
int i = 0;
mtu = ntohs(icp->icmp_ip.ip_len);
/* Some 4.2BSD-based routers incorrectly adjust the ip_len */
if (mtu > rt->rt_mtu && rt->rt_mtu != 0)
mtu -= (icp->icmp_ip.ip_hl << 2);
/* If we still can't guess a value, try the route */
if (mtu == 0) {
mtu = rt->rt_mtu;
/* If no route mtu, default to the interface mtu */
if (mtu == 0)
mtu = ifp->if_mtu;
}
for (i = 0; i < nitems(mtu_table); i++)
if (mtu > mtu_table[i]) {
mtu = mtu_table[i];
break;
}
}
/*
* XXX: RTV_MTU is overloaded, since the admin can set it
* to turn off PMTU for a route, and the kernel can
* set it to indicate a serious problem with PMTU
* on a route. We should be using a separate flag
* for the kernel to indicate this.
*/
if ((rt->rt_locks & RTV_MTU) == 0) {
if (mtu < 296 || mtu > ifp->if_mtu)
rt->rt_locks |= RTV_MTU;
else if (rt->rt_mtu > mtu || rt->rt_mtu == 0)
rt->rt_mtu = mtu;
}
if_put(ifp);
rtfree(rt);
}
void
icmp_mtudisc_timeout(struct rtentry *rt, u_int rtableid)
{
struct ifnet *ifp;
NET_ASSERT_LOCKED();
ifp = if_get(rt->rt_ifidx);
if (ifp == NULL)
return;
if ((rt->rt_flags & (RTF_DYNAMIC|RTF_HOST)) == (RTF_DYNAMIC|RTF_HOST)) {
void (*ctlfunc)(int, struct sockaddr *, u_int, void *);
struct sockaddr_in sin;
sin = *satosin(rt_key(rt));
rtdeletemsg(rt, ifp, rtableid);
/* Notify TCP layer of increased Path MTU estimate */
ctlfunc = inetsw[ip_protox[IPPROTO_TCP]].pr_ctlinput;
if (ctlfunc)
(*ctlfunc)(PRC_MTUINC, sintosa(&sin),
rtableid, NULL);
} else {
if ((rt->rt_locks & RTV_MTU) == 0)
rt->rt_mtu = 0;
}
if_put(ifp);
}
/*
* Perform rate limit check.
* Returns 0 if it is okay to send the icmp packet.
* Returns 1 if the router SHOULD NOT send this icmp packet due to rate
* limitation.
*
* XXX per-destination/type check necessary?
*/
int
icmp_ratelimit(const struct in_addr *dst, const int type, const int code)
{
/* PPS limit */
if (!ppsratecheck(&icmperrppslim_last, &icmperrpps_count,
icmperrppslim))
return 1; /* The packet is subject to rate limit */
return 0; /* okay to send */
}
int
icmp_do_exthdr(struct mbuf *m, u_int16_t class, u_int8_t ctype, void *buf,
size_t len)
{
struct ip *ip = mtod(m, struct ip *);
int hlen, off;
struct mbuf *n;
struct icmp *icp;
struct icmp_ext_hdr *ieh;
struct {
struct icmp_ext_hdr ieh;
struct icmp_ext_obj_hdr ieo;
} hdr;
hlen = ip->ip_hl << 2;
icp = (struct icmp *)(mtod(m, caddr_t) + hlen);
if (icp->icmp_type != ICMP_TIMXCEED && icp->icmp_type != ICMP_UNREACH &&
icp->icmp_type != ICMP_PARAMPROB)
/* exthdr not supported */
return (0);
if (icp->icmp_length != 0)
/* exthdr already present, giving up */
return (0);
/* the actual offset starts after the common ICMP header */
hlen += ICMP_MINLEN;
/* exthdr must start on a word boundary */
off = roundup(ntohs(ip->ip_len) - hlen, sizeof(u_int32_t));
/* ... and at an offset of ICMP_EXT_OFFSET or bigger */
off = max(off, ICMP_EXT_OFFSET);
icp->icmp_length = off / sizeof(u_int32_t);
memset(&hdr, 0, sizeof(hdr));
hdr.ieh.ieh_version = ICMP_EXT_HDR_VERSION;
hdr.ieo.ieo_length = htons(sizeof(struct icmp_ext_obj_hdr) + len);
hdr.ieo.ieo_cnum = class;
hdr.ieo.ieo_ctype = ctype;
if (m_copyback(m, hlen + off, sizeof(hdr), &hdr, M_NOWAIT) ||
m_copyback(m, hlen + off + sizeof(hdr), len, buf, M_NOWAIT)) {
m_freem(m);
return (ENOBUFS);
}
/* calculate checksum */
n = m_getptr(m, hlen + off, &off);
if (n == NULL)
panic("icmp_do_exthdr: m_getptr failure");
ieh = (struct icmp_ext_hdr *)(mtod(n, caddr_t) + off);
ieh->ieh_cksum = in4_cksum(n, 0, off, sizeof(hdr) + len);
ip->ip_len = htons(m->m_pkthdr.len);
return (0);
}
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