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freebsd-skq/sys/netinet/ip_icmp.c
Warner Losh 173c0f9f5c Mitigate the stream.c attacks 
o Drop all broadcast and multicast source addresses in tcp_input.
o Enable ICMP_BANDLIM in GENERIC.
o Change default to 200/s from 100/s.  This will still stop the attack, but
  is conservative enough to do this close to code freeze.

This is not the optimal patch for the problem, but is likely the least
intrusive patch that can be made for this.

Obtained from: Don Lewis and Matt Dillon.
Reviewed by: freebsd-security
2000-01-28 06:13:09 +00:00

866 lines
22 KiB
C
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/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
* $FreeBSD$
*/
#include "opt_ipsec.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/sysctl.h>
#include <net/if.h>
#include <net/route.h>
#define _IP_VHL
#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>
#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netkey/key.h>
#endif
#include "faith.h"
#if defined(NFAITH) && NFAITH > 0
#include <net/if_types.h>
#endif
/*
* ICMP routines: error generation, receive packet processing, and
* routines to turnaround packets back to the originator, and
* host table maintenance routines.
*/
static struct icmpstat icmpstat;
SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RD,
&icmpstat, icmpstat, "");
static int icmpmaskrepl = 0;
SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW,
&icmpmaskrepl, 0, "");
static int drop_redirect = 0;
SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW,
&drop_redirect, 0, "");
static int log_redirect = 0;
SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW,
&log_redirect, 0, "");
#ifdef ICMP_BANDLIM
/*
* ICMP error-response bandwidth limiting sysctl. If not enabled, sysctl
* variable content is -1 and read-only.
*/
static int icmplim = 200;
SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW,
&icmplim, 0, "");
#else
static int icmplim = -1;
SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD,
&icmplim, 0, "");
#endif
/*
* ICMP broadcast echo sysctl
*/
static int icmpbmcastecho = 0;
SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW,
&icmpbmcastecho, 0, "");
#ifdef ICMPPRINTFS
int icmpprintfs = 0;
#endif
static void icmp_reflect __P((struct mbuf *));
static void icmp_send __P((struct mbuf *, struct mbuf *));
static int ip_next_mtu __P((int, int));
extern struct protosw inetsw[];
/*
* Generate an error packet of type error
* in response to bad packet ip.
*/
void
icmp_error(n, type, code, dest, destifp)
struct mbuf *n;
int type, code;
n_long dest;
struct ifnet *destifp;
{
register struct ip *oip = mtod(n, struct ip *), *nip;
register unsigned oiplen = IP_VHL_HL(oip->ip_vhl) << 2;
register struct icmp *icp;
register struct mbuf *m;
unsigned icmplen;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_error(%p, %x, %d)\n", oip, type, code);
#endif
if (type != ICMP_REDIRECT)
icmpstat.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 &~ (IP_MF|IP_DF))
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.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, formulate icmp message
*/
m = m_gethdr(M_DONTWAIT, MT_HEADER);
if (m == NULL)
goto freeit;
icmplen = oiplen + min(8, oip->ip_len);
m->m_len = icmplen + ICMP_MINLEN;
MH_ALIGN(m, m->m_len);
icp = mtod(m, struct icmp *);
if ((u_int)type > ICMP_MAXTYPE)
panic("icmp_error");
icmpstat.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 && destifp) {
icp->icmp_nextmtu = htons(destifp->if_mtu);
}
}
icp->icmp_code = code;
bcopy((caddr_t)oip, (caddr_t)&icp->icmp_ip, icmplen);
nip = &icp->icmp_ip;
nip->ip_len = htons((u_short)(nip->ip_len + oiplen));
/*
* Now, copy old ip header (without options)
* in front of icmp message.
*/
if (m->m_data - sizeof(struct ip) < m->m_pktdat)
panic("icmp len");
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 = m->m_len;
nip->ip_vhl = IP_VHL_BORING;
nip->ip_p = IPPROTO_ICMP;
nip->ip_tos = 0;
icmp_reflect(m);
freeit:
m_freem(n);
}
static struct sockaddr_in icmpsrc = { sizeof (struct sockaddr_in), AF_INET };
static struct sockaddr_in icmpdst = { sizeof (struct sockaddr_in), AF_INET };
static struct sockaddr_in icmpgw = { sizeof (struct sockaddr_in), AF_INET };
/*
* Process a received ICMP message.
*/
void
icmp_input(m, off, proto)
register struct mbuf *m;
int off, proto;
{
int hlen = off;
register struct icmp *icp;
register struct ip *ip = mtod(m, struct ip *);
int icmplen = ip->ip_len;
register int i;
struct in_ifaddr *ia;
void (*ctlfunc) __P((int, struct sockaddr *, void *));
int code;
/*
* Locate icmp structure in mbuf, and check
* that not corrupted and of at least minimum length.
*/
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char buf[4 * sizeof "123"];
strcpy(buf, inet_ntoa(ip->ip_src));
printf("icmp_input from %s to %s, len %d\n",
buf, inet_ntoa(ip->ip_dst), icmplen);
}
#endif
if (icmplen < ICMP_MINLEN) {
icmpstat.icps_tooshort++;
goto freeit;
}
i = hlen + min(icmplen, ICMP_ADVLENMIN);
if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
icmpstat.icps_tooshort++;
return;
}
ip = mtod(m, struct ip *);
m->m_len -= hlen;
m->m_data += hlen;
icp = mtod(m, struct icmp *);
if (in_cksum(m, icmplen)) {
icmpstat.icps_checksum++;
goto freeit;
}
m->m_len += hlen;
m->m_data -= hlen;
#if defined(NFAITH) && 0 < NFAITH
if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) {
/*
* Deliver very specific ICMP type only.
*/
switch (icp->icmp_type) {
case ICMP_UNREACH:
case ICMP_TIMXCEED:
break;
default:
goto freeit;
}
}
#endif
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("icmp_input, type %d code %d\n", icp->icmp_type,
icp->icmp_code);
#endif
#ifdef IPSEC
/* drop it if it does not match the policy */
/* XXX Is there meaning of check in here ? */
if (ipsec4_in_reject(m, NULL)) {
ipsecstat.in_polvio++;
goto freeit;
}
#endif
/*
* Message type specific processing.
*/
if (icp->icmp_type > ICMP_MAXTYPE)
goto raw;
icmpstat.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:
code = PRC_UNREACH_HOST;
break;
case ICMP_UNREACH_FILTER_PROHIB:
case ICMP_UNREACH_HOST_PRECEDENCE:
case ICMP_UNREACH_PRECEDENCE_CUTOFF:
code = PRC_UNREACH_PORT;
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) ||
IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
icmpstat.icps_badlen++;
goto freeit;
}
NTOHS(icp->icmp_ip.ip_len);
/* Discard ICMP's in response to multicast packets */
if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr)))
goto badcode;
#ifdef ICMPPRINTFS
if (icmpprintfs)
printf("deliver to protocol %d\n", icp->icmp_ip.ip_p);
#endif
icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
#if 1
/*
* MTU discovery:
* If we got a needfrag and there is a host route to the
* original destination, and the MTU is not locked, then
* set the MTU in the route to the suggested new value
* (if given) and then notify as usual. The ULPs will
* notice that the MTU has changed and adapt accordingly.
* If no new MTU was suggested, then we guess a new one
* less than the current value. If the new MTU is
* unreasonably small (arbitrarily set at 296), then
* we reset the MTU to the interface value and enable the
* lock bit, indicating that we are no longer doing MTU
* discovery.
*/
if (code == PRC_MSGSIZE) {
struct rtentry *rt;
int mtu;
rt = rtalloc1((struct sockaddr *)&icmpsrc, 0,
RTF_CLONING | RTF_PRCLONING);
if (rt && (rt->rt_flags & RTF_HOST)
&& !(rt->rt_rmx.rmx_locks & RTV_MTU)) {
mtu = ntohs(icp->icmp_nextmtu);
if (!mtu)
mtu = ip_next_mtu(rt->rt_rmx.rmx_mtu,
1);
#ifdef DEBUG_MTUDISC
printf("MTU for %s reduced to %d\n",
inet_ntoa(icmpsrc.sin_addr), mtu);
#endif
if (mtu < 296) {
/* rt->rt_rmx.rmx_mtu =
rt->rt_ifp->if_mtu; */
rt->rt_rmx.rmx_locks |= RTV_MTU;
} else if (rt->rt_rmx.rmx_mtu > mtu) {
rt->rt_rmx.rmx_mtu = mtu;
}
}
if (rt)
RTFREE(rt);
}
#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, (struct sockaddr *)&icmpsrc,
(void *)&icp->icmp_ip);
break;
badcode:
icmpstat.icps_badcode++;
break;
case ICMP_ECHO:
if (!icmpbmcastecho
&& (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
icmpstat.icps_bmcastecho++;
break;
}
icp->icmp_type = ICMP_ECHOREPLY;
goto reflect;
case ICMP_TSTAMP:
if (!icmpbmcastecho
&& (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
icmpstat.icps_bmcasttstamp++;
break;
}
if (icmplen < ICMP_TSLEN) {
icmpstat.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:
#define satosin(sa) ((struct sockaddr_in *)(sa))
if (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 == 0)
break;
if (ia->ia_ifp == 0)
break;
icp->icmp_type = ICMP_MASKREPLY;
icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
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:
ip->ip_len += hlen; /* since ip_input deducts this */
icmpstat.icps_reflect++;
icmpstat.icps_outhist[icp->icmp_type]++;
icmp_reflect(m);
return;
case ICMP_REDIRECT:
if (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));
}
if (drop_redirect)
break;
if (code > 3)
goto badcode;
if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
icmpstat.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 buf[4 * sizeof "123"];
strcpy(buf, inet_ntoa(icp->icmp_ip.ip_dst));
printf("redirect dst %s to %s\n",
buf, inet_ntoa(icp->icmp_gwaddr));
}
#endif
icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
rtredirect((struct sockaddr *)&icmpsrc,
(struct sockaddr *)&icmpdst,
(struct sockaddr *)0, RTF_GATEWAY | RTF_HOST,
(struct sockaddr *)&icmpgw, (struct rtentry **)0);
pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
#ifdef IPSEC
key_sa_routechange((struct sockaddr *)&icmpsrc);
#endif
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:
default:
break;
}
raw:
rip_input(m, off, proto);
return;
freeit:
m_freem(m);
}
/*
* Reflect the ip packet back to the source
*/
static void
icmp_reflect(m)
struct mbuf *m;
{
register struct ip *ip = mtod(m, struct ip *);
register struct in_ifaddr *ia;
struct in_addr t;
struct mbuf *opts = 0;
int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
if (!in_canforward(ip->ip_src) &&
((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
(IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
m_freem(m); /* Bad return address */
goto done; /* Ip_output() will check for broadcast */
}
t = ip->ip_dst;
ip->ip_dst = ip->ip_src;
/*
* If the incoming packet was addressed directly to us,
* use dst as the src for the reply. Otherwise (broadcast
* or anonymous), use the address which corresponds
* to the incoming interface.
*/
for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr)
break;
if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr)
break;
}
icmpdst.sin_addr = t;
if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif)
ia = (struct in_ifaddr *)ifaof_ifpforaddr(
(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
/*
* The following happens if the packet was not addressed to us,
* and was received on an interface with no IP address.
*/
if (ia == (struct in_ifaddr *)0)
ia = in_ifaddrhead.tqh_first;
t = IA_SIN(ia)->sin_addr;
ip->ip_src = t;
ip->ip_ttl = MAXTTL;
if (optlen > 0) {
register 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()) == 0 &&
(opts = m_gethdr(M_DONTWAIT, MT_HEADER))) {
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 {
len = cp[IPOPT_OLEN];
if (len <= 0 || 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
}
/*
* Now strip out original options by copying rest of first
* mbuf's data back, and adjust the IP length.
*/
ip->ip_len -= optlen;
ip->ip_vhl = IP_VHL_BORING;
m->m_len -= optlen;
if (m->m_flags & M_PKTHDR)
m->m_pkthdr.len -= optlen;
optlen += sizeof(struct ip);
bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
(unsigned)(m->m_len - sizeof(struct ip)));
}
m->m_flags &= ~(M_BCAST|M_MCAST);
icmp_send(m, opts);
done:
if (opts)
(void)m_free(opts);
}
/*
* Send an icmp packet back to the ip level,
* after supplying a checksum.
*/
static void
icmp_send(m, opts)
register struct mbuf *m;
struct mbuf *opts;
{
register struct ip *ip = mtod(m, struct ip *);
register int hlen;
register struct icmp *icp;
struct route ro;
hlen = IP_VHL_HL(ip->ip_vhl) << 2;
m->m_data += hlen;
m->m_len -= hlen;
icp = mtod(m, struct icmp *);
icp->icmp_cksum = 0;
icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
m->m_data -= hlen;
m->m_len += hlen;
m->m_pkthdr.rcvif = (struct ifnet *)0;
#ifdef ICMPPRINTFS
if (icmpprintfs) {
char buf[4 * sizeof "123"];
strcpy(buf, inet_ntoa(ip->ip_dst));
printf("icmp_send dst %s src %s\n",
buf, inet_ntoa(ip->ip_src));
}
#endif
bzero(&ro, sizeof ro);
(void) ip_output(m, opts, &ro, 0, NULL);
if (ro.ro_rt)
RTFREE(ro.ro_rt);
}
n_time
iptime()
{
struct timeval atv;
u_long t;
microtime(&atv);
t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000;
return (htonl(t));
}
#if 1
/*
* Return the next larger or smaller MTU plateau (table from RFC 1191)
* given current value MTU. If DIR is less than zero, a larger plateau
* is returned; otherwise, a smaller value is returned.
*/
static int
ip_next_mtu(mtu, dir)
int mtu;
int dir;
{
static int mtutab[] = {
65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
68, 0
};
int i;
for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
if (mtu >= mtutab[i])
break;
}
if (dir < 0) {
if (i == 0) {
return 0;
} else {
return mtutab[i - 1];
}
} else {
if (mtutab[i] == 0) {
return 0;
} else if(mtu > mtutab[i]) {
return mtutab[i];
} else {
return mtutab[i + 1];
}
}
}
#endif
#ifdef ICMP_BANDLIM
/*
* badport_bandlim() - check for ICMP bandwidth limit
*
* Return 0 if it is ok to send an ICMP error response, -1 if we have
* hit our bandwidth limit and it is not ok.
*
* If icmplim is <= 0, the feature is disabled and 0 is returned.
*
* For now we separate the TCP and UDP subsystems w/ different 'which'
* values. We may eventually remove this separation (and simplify the
* code further).
*
* Note that the printing of the error message is delayed so we can
* properly print the icmp error rate that the system was trying to do
* (i.e. 22000/100 pps, etc...). This can cause long delays in printing
* the 'final' error, but it doesn't make sense to solve the printing
* delay with more complex code.
*/
int
badport_bandlim(int which)
{
static int lticks[2];
static int lpackets[2];
int dticks;
/*
* Return ok status if feature disabled or argument out of
* ranage.
*/
if (icmplim <= 0 || which >= 2 || which < 0)
return(0);
dticks = ticks - lticks[which];
/*
* reset stats when cumulative dt exceeds one second.
*/
if ((unsigned int)dticks > hz) {
if (lpackets[which] > icmplim) {
printf("icmp-response bandwidth limit %d/%d pps\n",
lpackets[which],
icmplim
);
}
lticks[which] = ticks;
lpackets[which] = 0;
}
/*
* bump packet count
*/
if (++lpackets[which] > icmplim) {
return(-1);
}
return(0);
}
#endif
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