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ip_icmp.c
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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
*/
#include <sys/cdefs.h>
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/route/route_ctl.h>
#include <net/route/nhop.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_fib.h>
#include <netinet/in_pcb.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/ip_options.h>
#include <netinet/sctp.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>
#include <netinet/icmp_var.h>
#ifdef INET
#include <machine/in_cksum.h>
#include <security/mac/mac_framework.h>
#endif /* INET */
extern ipproto_ctlinput_t *ip_ctlprotox[];
/*
* ICMP routines: error generation, receive packet processing, and
* routines to turnaround packets back to the originator, and
* host table maintenance routines.
*/
static int sysctl_icmplim_and_jitter(SYSCTL_HANDLER_ARGS);
VNET_DEFINE_STATIC(u_int, icmplim) = 200;
#define V_icmplim VNET(icmplim)
SYSCTL_PROC(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLTYPE_UINT |
CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim), 0,
&sysctl_icmplim_and_jitter, "IU",
"Maximum number of ICMP responses per second");
VNET_DEFINE_STATIC(int, icmplim_curr_jitter) = 0;
#define V_icmplim_curr_jitter VNET(icmplim_curr_jitter)
VNET_DEFINE_STATIC(u_int, icmplim_jitter) = 16;
#define V_icmplim_jitter VNET(icmplim_jitter)
SYSCTL_PROC(_net_inet_icmp, OID_AUTO, icmplim_jitter, CTLTYPE_UINT |
CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim_jitter), 0,
&sysctl_icmplim_and_jitter, "IU",
"Random icmplim jitter adjustment limit");
VNET_DEFINE_STATIC(int, icmplim_output) = 1;
#define V_icmplim_output VNET(icmplim_output)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmplim_output), 0,
"Enable logging of ICMP response rate limiting");
#ifdef INET
VNET_PCPUSTAT_DEFINE(struct icmpstat, icmpstat);
VNET_PCPUSTAT_SYSINIT(icmpstat);
SYSCTL_VNET_PCPUSTAT(_net_inet_icmp, ICMPCTL_STATS, stats, struct icmpstat,
icmpstat, "ICMP statistics (struct icmpstat, netinet/icmp_var.h)");
#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(icmpstat);
#endif /* VIMAGE */
VNET_DEFINE_STATIC(int, icmpmaskrepl) = 0;
#define V_icmpmaskrepl VNET(icmpmaskrepl)
SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmpmaskrepl), 0,
"Reply to ICMP Address Mask Request packets");
VNET_DEFINE_STATIC(u_int, icmpmaskfake) = 0;
#define V_icmpmaskfake VNET(icmpmaskfake)
SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmpmaskfake), 0,
"Fake reply to ICMP Address Mask Request packets");
VNET_DEFINE(int, drop_redirect) = 0;
#define V_drop_redirect VNET(drop_redirect)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(drop_redirect), 0,
"Ignore ICMP redirects");
VNET_DEFINE_STATIC(int, log_redirect) = 0;
#define V_log_redirect VNET(log_redirect)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(log_redirect), 0,
"Log ICMP redirects to the console");
VNET_DEFINE_STATIC(int, redirtimeout) = 60 * 10; /* 10 minutes */
#define V_redirtimeout VNET(redirtimeout)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, redirtimeout, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(redirtimeout), 0,
"Delay in seconds before expiring redirect route");
VNET_DEFINE_STATIC(char, reply_src[IFNAMSIZ]);
#define V_reply_src VNET(reply_src)
SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(reply_src), IFNAMSIZ,
"ICMP reply source for non-local packets");
VNET_DEFINE_STATIC(int, icmp_rfi) = 0;
#define V_icmp_rfi VNET(icmp_rfi)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmp_rfi), 0,
"ICMP reply from incoming interface for non-local packets");
/* Router requirements RFC 1812 section 4.3.2.3 requires 576 - 28. */
VNET_DEFINE_STATIC(int, icmp_quotelen) = 548;
#define V_icmp_quotelen VNET(icmp_quotelen)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmp_quotelen), 0,
"Number of bytes from original packet to quote in ICMP reply");
VNET_DEFINE_STATIC(int, icmpbmcastecho) = 0;
#define V_icmpbmcastecho VNET(icmpbmcastecho)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmpbmcastecho), 0,
"Reply to multicast ICMP Echo Request and Timestamp packets");
VNET_DEFINE_STATIC(int, icmptstamprepl) = 1;
#define V_icmptstamprepl VNET(icmptstamprepl)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, tstamprepl, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(icmptstamprepl), 0,
"Respond to ICMP Timestamp packets");
VNET_DEFINE_STATIC(int, error_keeptags) = 0;
#define V_error_keeptags VNET(error_keeptags)
SYSCTL_INT(_net_inet_icmp, OID_AUTO, error_keeptags, CTLFLAG_VNET | CTLFLAG_RW,
&VNET_NAME(error_keeptags), 0,
"ICMP error response keeps copy of mbuf_tags of original packet");
#ifdef ICMPPRINTFS
int icmpprintfs = 0;
#endif
static void icmp_reflect(struct mbuf *);
static void icmp_send(struct mbuf *, struct mbuf *);
static int icmp_verify_redirect_gateway(struct sockaddr_in *,
struct sockaddr_in *, struct sockaddr_in *, u_int);
/*
* Kernel module interface for updating icmpstat. The argument is an index
* into icmpstat treated as an array of u_long. While this encodes the
* general layout of icmpstat into the caller, it doesn't encode its
* location, so that future changes to add, for example, per-CPU stats
* support won't cause binary compatibility problems for kernel modules.
*/
void
kmod_icmpstat_inc(int statnum)
{
counter_u64_add(VNET(icmpstat)[statnum], 1);
}
/*
* Generate an error packet of type error
* in response to bad packet ip.
*/
void
icmp_error(struct mbuf *n, int type, int code, uint32_t dest, int mtu)
{
struct ip *oip, *nip;
struct icmp *icp;
struct mbuf *m;
unsigned icmplen, icmpelen, nlen, oiphlen;
KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type",
__func__));
if (type != ICMP_REDIRECT)
ICMPSTAT_INC(icps_error);
/*
* Don't send error:
* if the original packet was encrypted.
* if not the first fragment of message.
* in response to a multicast or broadcast packet.
* if the old packet protocol was an ICMP error message.
*/
if (n->m_flags & M_DECRYPTED)
goto freeit;
if (n->m_flags & (M_BCAST|M_MCAST))
goto freeit;
/* Drop if IP header plus 8 bytes is not contiguous in first mbuf. */
if (n->m_len < sizeof(struct ip) + ICMP_MINLEN)
goto freeit;
oip = mtod(n, struct ip *);
oiphlen = oip->ip_hl << 2;
if (n->m_len < oiphlen + ICMP_MINLEN)
goto freeit;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_error(%p, %x, %d)\n", oip, type, code);
#endif
if (oip->ip_off & htons(~(IP_MF|IP_DF)))
goto freeit;
if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
!ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip +
oiphlen))->icmp_type)) {
ICMPSTAT_INC(icps_oldicmp);
goto freeit;
}
/*
* Calculate length to quote from original packet and
* prevent the ICMP mbuf from overflowing.
* Unfortunately this is non-trivial since ip_forward()
* sends us truncated packets.
*/
nlen = m_length(n, NULL);
if (oip->ip_p == IPPROTO_TCP) {
struct tcphdr *th;
int tcphlen;
if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
n->m_next == NULL)
goto stdreply;
if (n->m_len < oiphlen + sizeof(struct tcphdr) &&
(n = m_pullup(n, oiphlen + sizeof(struct tcphdr))) == NULL)
goto freeit;
oip = mtod(n, struct ip *);
th = mtodo(n, oiphlen);
tcphlen = th->th_off << 2;
if (tcphlen < sizeof(struct tcphdr))
goto freeit;
if (ntohs(oip->ip_len) < oiphlen + tcphlen)
goto freeit;
if (oiphlen + tcphlen > n->m_len && n->m_next == NULL)
goto stdreply;
if (n->m_len < oiphlen + tcphlen &&
(n = m_pullup(n, oiphlen + tcphlen)) == NULL)
goto freeit;
oip = mtod(n, struct ip *);
icmpelen = max(tcphlen, min(V_icmp_quotelen,
ntohs(oip->ip_len) - oiphlen));
} else if (oip->ip_p == IPPROTO_SCTP) {
struct sctphdr *sh;
struct sctp_chunkhdr *ch;
if (ntohs(oip->ip_len) < oiphlen + sizeof(struct sctphdr))
goto stdreply;
if (oiphlen + sizeof(struct sctphdr) > n->m_len &&
n->m_next == NULL)
goto stdreply;
if (n->m_len < oiphlen + sizeof(struct sctphdr) &&
(n = m_pullup(n, oiphlen + sizeof(struct sctphdr))) == NULL)
goto freeit;
oip = mtod(n, struct ip *);
icmpelen = max(sizeof(struct sctphdr),
min(V_icmp_quotelen, ntohs(oip->ip_len) - oiphlen));
sh = mtodo(n, oiphlen);
if (ntohl(sh->v_tag) == 0 &&
ntohs(oip->ip_len) >= oiphlen +
sizeof(struct sctphdr) + 8 &&
(n->m_len >= oiphlen + sizeof(struct sctphdr) + 8 ||
n->m_next != NULL)) {
if (n->m_len < oiphlen + sizeof(struct sctphdr) + 8 &&
(n = m_pullup(n, oiphlen +
sizeof(struct sctphdr) + 8)) == NULL)
goto freeit;
oip = mtod(n, struct ip *);
sh = mtodo(n, oiphlen);
ch = (struct sctp_chunkhdr *)(sh + 1);
if (ch->chunk_type == SCTP_INITIATION) {
icmpelen = max(sizeof(struct sctphdr) + 8,
min(V_icmp_quotelen, ntohs(oip->ip_len) -
oiphlen));
}
}
} else
stdreply: icmpelen = max(8, min(V_icmp_quotelen, ntohs(oip->ip_len) -
oiphlen));
icmplen = min(oiphlen + icmpelen, nlen);
if (icmplen < sizeof(struct ip))
goto freeit;
if (MHLEN > sizeof(struct ip) + ICMP_MINLEN + icmplen)
m = m_gethdr(M_NOWAIT, MT_DATA);
else
m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
if (m == NULL)
goto freeit;
#ifdef MAC
mac_netinet_icmp_reply(n, m);
#endif
icmplen = min(icmplen, M_TRAILINGSPACE(m) -
sizeof(struct ip) - ICMP_MINLEN);
m_align(m, sizeof(struct ip) + ICMP_MINLEN + icmplen);
m->m_data += sizeof(struct ip);
m->m_len = ICMP_MINLEN + icmplen;
/* XXX MRT make the outgoing packet use the same FIB
* that was associated with the incoming packet
*/
M_SETFIB(m, M_GETFIB(n));
icp = mtod(m, struct icmp *);
ICMPSTAT_INC2(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
* just zeroed icmp_void field.
*/
if (type == ICMP_PARAMPROB) {
icp->icmp_pptr = code;
code = 0;
} else if (type == ICMP_UNREACH &&
code == ICMP_UNREACH_NEEDFRAG && mtu) {
icp->icmp_nextmtu = htons(mtu);
}
}
icp->icmp_code = code;
/*
* Copy the quotation into ICMP message and
* convert quoted IP header back to network representation.
*/
m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
nip = &icp->icmp_ip;
/*
* Set up ICMP message mbuf and copy old IP header (without options
* in front of ICMP message.
* If the original mbuf was meant to bypass the firewall, the error
* reply should bypass as well.
*/
m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
KASSERT(M_LEADINGSPACE(m) >= sizeof(struct ip),
("insufficient space for ip header"));
m->m_data -= sizeof(struct ip);
m->m_len += sizeof(struct ip);
m->m_pkthdr.len = m->m_len;
m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
nip = mtod(m, struct ip *);
bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
nip->ip_len = htons(m->m_len);
nip->ip_v = IPVERSION;
nip->ip_hl = 5;
nip->ip_p = IPPROTO_ICMP;
nip->ip_tos = 0;
nip->ip_off = 0;
if (V_error_keeptags)
m_tag_copy_chain(m, n, M_NOWAIT);
icmp_reflect(m);
freeit:
m_freem(n);
}
int
icmp_errmap(const struct icmp *icp)
{
switch (icp->icmp_type) {
case ICMP_UNREACH:
switch (icp->icmp_code) {
case ICMP_UNREACH_NET:
case ICMP_UNREACH_HOST:
case ICMP_UNREACH_SRCFAIL:
case ICMP_UNREACH_NET_UNKNOWN:
case ICMP_UNREACH_HOST_UNKNOWN:
case ICMP_UNREACH_ISOLATED:
case ICMP_UNREACH_TOSNET:
case ICMP_UNREACH_TOSHOST:
case ICMP_UNREACH_HOST_PRECEDENCE:
case ICMP_UNREACH_PRECEDENCE_CUTOFF:
return (EHOSTUNREACH);
case ICMP_UNREACH_NEEDFRAG:
return (EMSGSIZE);
case ICMP_UNREACH_PROTOCOL:
case ICMP_UNREACH_PORT:
case ICMP_UNREACH_NET_PROHIB:
case ICMP_UNREACH_HOST_PROHIB:
case ICMP_UNREACH_FILTER_PROHIB:
return (ECONNREFUSED);
default:
return (0);
}
case ICMP_TIMXCEED:
switch (icp->icmp_code) {
case ICMP_TIMXCEED_INTRANS:
return (EHOSTUNREACH);
default:
return (0);
}
case ICMP_PARAMPROB:
switch (icp->icmp_code) {
case ICMP_PARAMPROB_ERRATPTR:
case ICMP_PARAMPROB_OPTABSENT:
return (ENOPROTOOPT);
default:
return (0);
}
default:
return (0);
}
}
/*
* Process a received ICMP message.
*/
int
icmp_input(struct mbuf **mp, int *offp, int proto)
{
struct icmp *icp;
struct in_ifaddr *ia;
struct mbuf *m = *mp;
struct ip *ip = mtod(m, struct ip *);
struct sockaddr_in icmpsrc, icmpdst, icmpgw;
int hlen = *offp;
int icmplen = ntohs(ip->ip_len) - *offp;
int i, code;
int fibnum;
NET_EPOCH_ASSERT();
*mp = NULL;
/*
* Locate icmp structure in mbuf, and check
* that not corrupted and of at least minimum length.
*/
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char srcbuf[INET_ADDRSTRLEN];
char dstbuf[INET_ADDRSTRLEN];
printf("icmp_input from %s to %s, len %d\n",
inet_ntoa_r(ip->ip_src, srcbuf),
inet_ntoa_r(ip->ip_dst, dstbuf), icmplen);
}
#endif
if (icmplen < ICMP_MINLEN) {
ICMPSTAT_INC(icps_tooshort);
goto freeit;
}
i = hlen + min(icmplen, ICMP_ADVLENMIN);
if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
ICMPSTAT_INC(icps_tooshort);
return (IPPROTO_DONE);
}
ip = mtod(m, struct ip *);
m->m_len -= hlen;
m->m_data += hlen;
icp = mtod(m, struct icmp *);
if (in_cksum(m, icmplen)) {
ICMPSTAT_INC(icps_checksum);
goto freeit;
}
m->m_len += hlen;
m->m_data -= hlen;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_input, type %d code %d\n", icp->icmp_type,
icp->icmp_code);
#endif
/*
* Message type specific processing.
*/
if (icp->icmp_type > ICMP_MAXTYPE)
goto raw;
/* Initialize */
bzero(&icmpsrc, sizeof(icmpsrc));
icmpsrc.sin_len = sizeof(struct sockaddr_in);
icmpsrc.sin_family = AF_INET;
bzero(&icmpdst, sizeof(icmpdst));
icmpdst.sin_len = sizeof(struct sockaddr_in);
icmpdst.sin_family = AF_INET;
bzero(&icmpgw, sizeof(icmpgw));
icmpgw.sin_len = sizeof(struct sockaddr_in);
icmpgw.sin_family = AF_INET;
ICMPSTAT_INC2(icps_inhist, icp->icmp_type);
code = icp->icmp_code;
switch (icp->icmp_type) {
case ICMP_UNREACH:
if (code > ICMP_UNREACH_PRECEDENCE_CUTOFF)
goto badcode;
else
goto deliver;
case ICMP_TIMXCEED:
if (code > ICMP_TIMXCEED_REASS)
goto badcode;
else
goto deliver;
case ICMP_PARAMPROB:
if (code > ICMP_PARAMPROB_LENGTH)
goto badcode;
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;
}
/* Discard ICMP's in response to multicast packets */
if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
goto badcode;
/* Filter out responses to INADDR_ANY, protocols ignore it. */
if (icp->icmp_ip.ip_dst.s_addr == INADDR_ANY ||
icp->icmp_ip.ip_src.s_addr == INADDR_ANY)
goto freeit;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
#endif
/*
* XXX if the packet contains [IPv4 AH TCP], we can't make a
* notification to TCP layer.
*/
i = sizeof(struct ip) + min(icmplen, ICMP_ADVLENPREF(icp));
ip_stripoptions(m);
if (m->m_len < i && (m = m_pullup(m, i)) == NULL) {
/* This should actually not happen */
ICMPSTAT_INC(icps_tooshort);
return (IPPROTO_DONE);
}
ip = mtod(m, struct ip *);
icp = (struct icmp *)(ip + 1);
/*
* The upper layer handler can rely on:
* - The outer IP header has no options.
* - The outer IP header, the ICMP header, the inner IP header,
* and the first n bytes of the inner payload are contiguous.
* n is at least 8, but might be larger based on
* ICMP_ADVLENPREF. See its definition in ip_icmp.h.
*/
if (ip_ctlprotox[icp->icmp_ip.ip_p] != NULL)
ip_ctlprotox[icp->icmp_ip.ip_p](icp);
break;
badcode:
ICMPSTAT_INC(icps_badcode);
break;
case ICMP_ECHO:
if (!V_icmpbmcastecho
&& (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
ICMPSTAT_INC(icps_bmcastecho);
break;
}
if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0)
goto freeit;
icp->icmp_type = ICMP_ECHOREPLY;
goto reflect;
case ICMP_TSTAMP:
if (V_icmptstamprepl == 0)
break;
if (!V_icmpbmcastecho
&& (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
ICMPSTAT_INC(icps_bmcasttstamp);
break;
}
if (icmplen < ICMP_TSLEN) {
ICMPSTAT_INC(icps_badlen);
break;
}
if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0)
goto freeit;
icp->icmp_type = ICMP_TSTAMPREPLY;
icp->icmp_rtime = iptime();
icp->icmp_ttime = icp->icmp_rtime; /* bogus, do later! */
goto reflect;
case ICMP_MASKREQ:
if (V_icmpmaskrepl == 0)
break;
/*
* We are not able to respond with all ones broadcast
* unless we receive it over a point-to-point interface.
*/
if (icmplen < ICMP_MASKLEN)
break;
switch (ip->ip_dst.s_addr) {
case INADDR_BROADCAST:
case INADDR_ANY:
icmpdst.sin_addr = ip->ip_src;
break;
default:
icmpdst.sin_addr = ip->ip_dst;
}
ia = (struct in_ifaddr *)ifaof_ifpforaddr(
(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
if (ia == NULL)
break;
if (ia->ia_ifp == NULL)
break;
icp->icmp_type = ICMP_MASKREPLY;
if (V_icmpmaskfake == 0)
icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
else
icp->icmp_mask = V_icmpmaskfake;
if (ip->ip_src.s_addr == 0) {
if (ia->ia_ifp->if_flags & IFF_BROADCAST)
ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT)
ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
}
reflect:
ICMPSTAT_INC(icps_reflect);
ICMPSTAT_INC2(icps_outhist, icp->icmp_type);
icmp_reflect(m);
return (IPPROTO_DONE);
case ICMP_REDIRECT:
if (V_log_redirect) {
u_long src, dst, gw;
src = ntohl(ip->ip_src.s_addr);
dst = ntohl(icp->icmp_ip.ip_dst.s_addr);
gw = ntohl(icp->icmp_gwaddr.s_addr);
printf("icmp redirect from %d.%d.%d.%d: "
"%d.%d.%d.%d => %d.%d.%d.%d\n",
(int)(src >> 24), (int)((src >> 16) & 0xff),
(int)((src >> 8) & 0xff), (int)(src & 0xff),
(int)(dst >> 24), (int)((dst >> 16) & 0xff),
(int)((dst >> 8) & 0xff), (int)(dst & 0xff),
(int)(gw >> 24), (int)((gw >> 16) & 0xff),
(int)((gw >> 8) & 0xff), (int)(gw & 0xff));
}
/*
* RFC1812 says we must ignore ICMP redirects if we
* are acting as router.
*/
if (V_drop_redirect || V_ipforwarding)
break;
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).
*/
icmpgw.sin_addr = ip->ip_src;
icmpdst.sin_addr = icp->icmp_gwaddr;
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char dstbuf[INET_ADDRSTRLEN];
char gwbuf[INET_ADDRSTRLEN];
printf("redirect dst %s to %s\n",
inet_ntoa_r(icp->icmp_ip.ip_dst, dstbuf),
inet_ntoa_r(icp->icmp_gwaddr, gwbuf));
}
#endif
icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
/*
* RFC 1122 says network (code 0,2) redirects SHOULD
* be treated identically to the host redirects.
* Given that, ignore network masks.
*/
/*
* Variable values:
* icmpsrc: route destination
* icmpdst: route gateway
* icmpgw: message source
*/
if (icmp_verify_redirect_gateway(&icmpgw, &icmpsrc, &icmpdst,
M_GETFIB(m)) != 0) {
/* TODO: increment bad redirects here */
break;
}
for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
rib_add_redirect(fibnum, (struct sockaddr *)&icmpsrc,
(struct sockaddr *)&icmpdst,
(struct sockaddr *)&icmpgw, m->m_pkthdr.rcvif,
RTF_GATEWAY, V_redirtimeout);
}
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_SOURCEQUENCH:
default:
break;
}
raw:
*mp = m;
rip_input(mp, offp, proto);
return (IPPROTO_DONE);
freeit:
m_freem(m);
return (IPPROTO_DONE);
}
/*
* Reflect the ip packet back to the source
*/
static void
icmp_reflect(struct mbuf *m)
{
struct ip *ip = mtod(m, struct ip *);
struct ifaddr *ifa;
struct ifnet *ifp;
struct in_ifaddr *ia;
struct in_addr t;
struct nhop_object *nh;
struct mbuf *opts = NULL;
int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
NET_EPOCH_ASSERT();
if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
(IN_EXPERIMENTAL(ntohl(ip->ip_src.s_addr)) && !V_ip_allow_net240) ||
(IN_ZERONET(ntohl(ip->ip_src.s_addr)) && !V_ip_allow_net0) ) {
m_freem(m); /* Bad return address */
ICMPSTAT_INC(icps_badaddr);
goto done; /* Ip_output() will check for broadcast */
}
t = ip->ip_dst;
ip->ip_dst = ip->ip_src;
/*
* Source selection for ICMP replies:
*
* If the incoming packet was addressed directly to one of our
* own addresses, use dst as the src for the reply.
*/
CK_LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
t = IA_SIN(ia)->sin_addr;
goto match;
}
}
/*
* If the incoming packet was addressed to one of our broadcast
* addresses, use the first non-broadcast address which corresponds
* to the incoming interface.
*/
ifp = m->m_pkthdr.rcvif;
if (ifp != NULL && ifp->if_flags & IFF_BROADCAST) {
CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
t.s_addr) {
t = IA_SIN(ia)->sin_addr;
goto match;
}
}
}
/*
* If the packet was transiting through us, use the address of
* the interface the packet came through in. If that interface
* doesn't have a suitable IP address, the normal selection
* criteria apply.
*/
if (V_icmp_rfi && ifp != NULL) {
CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
t = IA_SIN(ia)->sin_addr;
goto match;
}
}
/*
* If the incoming packet was not addressed directly to us, use
* designated interface for icmp replies specified by sysctl
* net.inet.icmp.reply_src (default not set). Otherwise continue
* with normal source selection.
*/
if (V_reply_src[0] != '\0' && (ifp = ifunit(V_reply_src))) {
CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
t = IA_SIN(ia)->sin_addr;
goto match;
}
}
/*
* If the packet was transiting through us, use the address of
* the interface that is the closest to the packet source.
* When we don't have a route back to the packet source, stop here
* and drop the packet.
*/
nh = fib4_lookup(M_GETFIB(m), ip->ip_dst, 0, NHR_NONE, 0);
if (nh == NULL) {
m_freem(m);
ICMPSTAT_INC(icps_noroute);
goto done;
}
t = IA_SIN(ifatoia(nh->nh_ifa))->sin_addr;
match:
#ifdef MAC
mac_netinet_icmp_replyinplace(m);
#endif
ip->ip_src = t;
ip->ip_ttl = V_ip_defttl;
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 ((opts = ip_srcroute(m)) == NULL &&
(opts = m_gethdr(M_NOWAIT, MT_DATA))) {
opts->m_len = sizeof(struct in_addr);
mtod(opts, struct in_addr *)->s_addr = 0;
}
if (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) {
bcopy((caddr_t)cp,
mtod(opts, caddr_t) + opts->m_len, len);
opts->m_len += len;
}
}
/* Terminate & pad, if necessary */
cnt = opts->m_len % 4;
if (cnt) {
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_tag_delete_nonpersistent(m);
m->m_flags &= ~(M_BCAST|M_MCAST);
icmp_send(m, opts);
done:
if (opts)
(void)m_free(opts);
}
/*
* Verifies if redirect message is valid, according to RFC 1122
*
* @src: sockaddr with address of redirect originator
* @dst: sockaddr with destination in question
* @gateway: new proposed gateway
*
* Returns 0 on success.
*/
static int
icmp_verify_redirect_gateway(struct sockaddr_in *src, struct sockaddr_in *dst,
struct sockaddr_in *gateway, u_int fibnum)
{
struct nhop_object *nh;
struct ifaddr *ifa;
NET_EPOCH_ASSERT();
/* Verify the gateway is directly reachable. */
if ((ifa = ifa_ifwithnet((struct sockaddr *)gateway, 0, fibnum))==NULL)
return (ENETUNREACH);
/* TODO: fib-aware. */
if (ifa_ifwithaddr_check((struct sockaddr *)gateway))
return (EHOSTUNREACH);
nh = fib4_lookup(fibnum, dst->sin_addr, 0, NHR_NONE, 0);
if (nh == NULL)
return (EINVAL);
/*
* If the redirect isn't from our current router for this dst,
* it's either old or wrong. If it redirects us to ourselves,
* we have a routing loop, perhaps as a result of an interface
* going down recently.
*/
if (!sa_equal((struct sockaddr *)src, &nh->gw_sa))
return (EINVAL);
if (nh->nh_ifa != ifa && ifa->ifa_addr->sa_family != AF_LINK)
return (EINVAL);
/* If host route already exists, ignore redirect. */
if (nh->nh_flags & NHF_HOST)
return (EEXIST);
/* If the prefix is directly reachable, ignore redirect. */
if (!(nh->nh_flags & NHF_GATEWAY))
return (EEXIST);
return (0);
}