/*- * 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. * 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 "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef IPSEC #include #include #endif #include #include /* * ICMP routines: error generation, receive packet processing, and * routines to turnaround packets back to the originator, and * host table maintenance routines. */ struct icmpstat icmpstat; SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats, CTLFLAG_RW, &icmpstat, icmpstat, ""); static int icmpmaskrepl = 0; SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl, CTLFLAG_RW, &icmpmaskrepl, 0, "Reply to ICMP Address Mask Request packets."); static u_int icmpmaskfake = 0; SYSCTL_UINT(_net_inet_icmp, OID_AUTO, maskfake, CTLFLAG_RW, &icmpmaskfake, 0, "Fake reply to ICMP Address Mask Request packets."); static int drop_redirect = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect, CTLFLAG_RW, &drop_redirect, 0, "Ignore ICMP redirects"); static int log_redirect = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect, CTLFLAG_RW, &log_redirect, 0, "Log ICMP redirects to the console"); static int icmplim = 200; SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW, &icmplim, 0, "Maximum number of ICMP responses per second"); static int icmplim_output = 1; SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_output, CTLFLAG_RW, &icmplim_output, 0, "Enable rate limiting of ICMP responses"); static char reply_src[IFNAMSIZ]; SYSCTL_STRING(_net_inet_icmp, OID_AUTO, reply_src, CTLFLAG_RW, &reply_src, IFNAMSIZ, "icmp reply source for non-local packets."); static int icmp_rfi = 0; SYSCTL_INT(_net_inet_icmp, OID_AUTO, reply_from_interface, CTLFLAG_RW, &icmp_rfi, 0, "ICMP reply from incoming interface for " "non-local packets"); static int icmp_quotelen = 8; SYSCTL_INT(_net_inet_icmp, OID_AUTO, quotelen, CTLFLAG_RW, &icmp_quotelen, 0, "Number of bytes from original packet to " "quote in ICMP reply"); /* * 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(struct mbuf *); static void icmp_send(struct mbuf *, struct mbuf *); extern struct protosw inetsw[]; /* * Generate an error packet of type error * in response to bad packet ip. */ void icmp_error(struct mbuf *n, int type, int code, n_long dest, int mtu) { register struct ip *oip = mtod(n, struct ip *), *nip; register unsigned oiphlen = oip->ip_hl << 2; register struct icmp *icp; register struct mbuf *m; unsigned icmplen, icmpelen, nlen; KASSERT((u_int)type <= ICMP_MAXTYPE, ("%s: illegal ICMP type", __func__)); #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 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 (oip->ip_off & ~(IP_MF|IP_DF)) goto freeit; if (n->m_flags & (M_BCAST|M_MCAST)) goto freeit; if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT && n->m_len >= oiphlen + ICMP_MINLEN && !ICMP_INFOTYPE(((struct icmp *)((caddr_t)oip + oiphlen))->icmp_type)) { icmpstat.icps_oldicmp++; goto freeit; } /* Drop if IP header plus 8 bytes is not contignous in first mbuf. */ if (oiphlen + 8 > n->m_len) goto freeit; /* * Calculate length to quote from original packet and * prevent the ICMP mbuf from overflowing. * Unfortunatly 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; th = (struct tcphdr *)((caddr_t)oip + oiphlen); tcphlen = th->th_off << 2; if (tcphlen < sizeof(struct tcphdr)) goto freeit; if (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; icmpelen = max(tcphlen, min(icmp_quotelen, oip->ip_len - oiphlen)); } else stdreply: icmpelen = max(8, min(icmp_quotelen, 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_DONTWAIT, MT_DATA); else m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR); if (m == NULL) goto freeit; #ifdef MAC mac_create_mbuf_netlayer(n, m); #endif icmplen = min(icmplen, M_TRAILINGSPACE(m) - sizeof(struct ip) - ICMP_MINLEN); m_align(m, ICMP_MINLEN + icmplen); m->m_len = ICMP_MINLEN + icmplen; icp = mtod(m, struct icmp *); 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 * 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; nip->ip_len = htons(nip->ip_len); nip->ip_off = htons(nip->ip_off); /* * 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; 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_v = IPVERSION; nip->ip_hl = 5; nip->ip_p = IPPROTO_ICMP; nip->ip_tos = 0; icmp_reflect(m); freeit: m_freem(n); } /* * Process a received ICMP message. */ void icmp_input(struct mbuf *m, int off) { struct icmp *icp; struct in_ifaddr *ia; struct ip *ip = mtod(m, struct ip *); struct sockaddr_in icmpsrc, icmpdst, icmpgw; int hlen = off; int icmplen = ip->ip_len; int i, code; void (*ctlfunc)(int, struct sockaddr *, void *); /* * 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 (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; } } #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.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_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: code = PRC_UNREACH_NET; break; case ICMP_UNREACH_NEEDFRAG: code = PRC_MSGSIZE; break; /* * RFC 1122, Sections 3.2.2.1 and 4.2.3.9. * Treat subcodes 2,3 as immediate RST */ case ICMP_UNREACH_PROTOCOL: case ICMP_UNREACH_PORT: code = PRC_UNREACH_PORT; break; case ICMP_UNREACH_NET_PROHIB: case ICMP_UNREACH_HOST_PROHIB: case ICMP_UNREACH_FILTER_PROHIB: code = PRC_UNREACH_ADMIN_PROHIB; 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.icps_badlen++; goto freeit; } icp->icmp_ip.ip_len = 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; /* * 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; if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) goto freeit; else 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! */ if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) goto freeit; else goto reflect; case ICMP_MASKREQ: 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; if (icmpmaskfake == 0) icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr; else icp->icmp_mask = 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: 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)); } /* * RFC1812 says we must ignore ICMP redirects if we * are acting as router. */ if (drop_redirect || 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.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); 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); return; freeit: m_freem(m); } /* * 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 *ifn; struct in_ifaddr *ia; struct in_addr t; struct mbuf *opts = 0; int optlen = (ip->ip_hl << 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 */ icmpstat.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. */ LIST_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) if (t.s_addr == IA_SIN(ia)->sin_addr.s_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. */ if (m->m_pkthdr.rcvif != NULL && m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) { TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->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) 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 (icmp_rfi && m->m_pkthdr.rcvif != NULL) { TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrhead, ifa_link) { if (ifa->ifa_addr->sa_family != AF_INET) continue; ia = ifatoia(ifa); 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 (reply_src[0] != '\0' && (ifn = ifunit(reply_src))) { TAILQ_FOREACH(ifa, &ifn->if_addrhead, ifa_link) { if (ifa->ifa_addr->sa_family != AF_INET) continue; ia = ifatoia(ifa); 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. */ ia = ip_rtaddr(ip->ip_dst); if (ia == NULL) { m_freem(m); icmpstat.icps_noroute++; goto done; } match: #ifdef MAC mac_reflect_mbuf_icmp(m); #endif t = IA_SIN(ia)->sin_addr; ip->ip_src = t; ip->ip_ttl = ip_defttl; 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(m)) == 0 && (opts = m_gethdr(M_DONTWAIT, 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 } /* * 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_v = IPVERSION; ip->ip_hl = 5; 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_tag_delete_nonpersistent(m); 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(struct mbuf *m, struct mbuf *opts) { register struct ip *ip = mtod(m, struct ip *); register int hlen; register struct icmp *icp; hlen = ip->ip_hl << 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 (void) ip_output(m, opts, NULL, 0, NULL, NULL); } n_time iptime(void) { struct timeval atv; u_long t; getmicrotime(&atv); t = (atv.tv_sec % (24*60*60)) * 1000 + atv.tv_usec / 1000; return (htonl(t)); } /* * 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. */ int ip_next_mtu(int mtu, int dir) { static int mtutab[] = { 65535, 32000, 17914, 8166, 4352, 2002, 1492, 1280, 1006, 508, 296, 68, 0 }; int i, size; size = (sizeof mtutab) / (sizeof mtutab[0]); if (dir >= 0) { for (i = 0; i < size; i++) if (mtu > mtutab[i]) return mtutab[i]; } else { for (i = size - 1; i >= 0; i--) if (mtu < mtutab[i]) return mtutab[i]; if (mtu == mtutab[0]) return mtutab[0]; } return 0; } /* * 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) { #define N(a) (sizeof (a) / sizeof (a[0])) static struct rate { const char *type; struct timeval lasttime; int curpps; } rates[BANDLIM_MAX+1] = { { "icmp unreach response" }, { "icmp ping response" }, { "icmp tstamp response" }, { "closed port RST response" }, { "open port RST response" }, { "icmp6 unreach response" } }; /* * Return ok status if feature disabled or argument out of range. */ if (icmplim > 0 && (u_int) which < N(rates)) { struct rate *r = &rates[which]; int opps = r->curpps; if (!ppsratecheck(&r->lasttime, &r->curpps, icmplim)) return -1; /* discard packet */ /* * If we've dropped below the threshold after having * rate-limited traffic print the message. This preserves * the previous behaviour at the expense of added complexity. */ if (icmplim_output && opps > icmplim) printf("Limiting %s from %d to %d packets/sec\n", r->type, opps, icmplim); } return 0; /* okay to send packet */ #undef N }