/*- * 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. * * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94 */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET #include #include #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. */ VNET_DEFINE_STATIC(int, icmplim) = 200; #define V_icmplim VNET(icmplim) SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim), 0, "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(int, icmplim_jitter) = 16; #define V_icmplim_jitter VNET(icmplim_jitter) SYSCTL_INT(_net_inet_icmp, OID_AUTO, icmplim_jitter, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(icmplim_jitter), 0, "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_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 * 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_INC(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) 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_INC(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); } /* * Send an icmp packet back to the ip level, * after supplying a checksum. */ static 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; m->m_data += hlen; m->m_len -= hlen; icp = mtod(m, struct icmp *); icp->icmp_cksum = 0; icp->icmp_cksum = in_cksum(m, ntohs(ip->ip_len) - hlen); m->m_data -= hlen; m->m_len += hlen; m->m_pkthdr.rcvif = (struct ifnet *)0; #ifdef ICMPPRINTFS if (icmpprintfs) { char dstbuf[INET_ADDRSTRLEN]; char srcbuf[INET_ADDRSTRLEN]; printf("icmp_send dst %s src %s\n", inet_ntoa_r(ip->ip_dst, dstbuf), inet_ntoa_r(ip->ip_src, srcbuf)); } #endif (void) ip_output(m, opts, NULL, 0, NULL, NULL); } /* * Return milliseconds since 00:00 UTC in network format. */ uint32_t 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; } #endif /* INET */ /* * 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. */ struct icmp_rate { const char *descr; struct counter_rate cr; }; VNET_DEFINE_STATIC(struct icmp_rate, icmp_rates[BANDLIM_MAX]) = { { "icmp unreach response" }, { "icmp ping response" }, { "icmp tstamp response" }, { "closed port RST response" }, { "open port RST response" }, { "icmp6 unreach response" }, { "sctp ootb response" } }; #define V_icmp_rates VNET(icmp_rates) static void icmp_bandlimit_init(void) { for (int i = 0; i < BANDLIM_MAX; i++) { V_icmp_rates[i].cr.cr_rate = counter_u64_alloc(M_WAITOK); V_icmp_rates[i].cr.cr_ticks = ticks; } } VNET_SYSINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, icmp_bandlimit_init, NULL); static void icmp_bandlimit_uninit(void) { for (int i = 0; i < BANDLIM_MAX; i++) counter_u64_free(V_icmp_rates[i].cr.cr_rate); } VNET_SYSUNINIT(icmp_bandlimit, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, icmp_bandlimit_uninit, NULL); int badport_bandlim(int which) { int64_t pps; if (V_icmplim == 0 || which == BANDLIM_UNLIMITED) return (0); KASSERT(which >= 0 && which < BANDLIM_MAX, ("%s: which %d", __func__, which)); if ((V_icmplim + V_icmplim_curr_jitter) <= 0) V_icmplim_curr_jitter = -V_icmplim + 1; pps = counter_ratecheck(&V_icmp_rates[which].cr, V_icmplim + V_icmplim_curr_jitter); if (pps > 0) { /* * Adjust limit +/- to jitter the measurement to deny a * side-channel port scan as in CVE-2020-25705 */ if (V_icmplim_jitter > 0) { int32_t inc = arc4random_uniform(V_icmplim_jitter * 2 +1) - V_icmplim_jitter; V_icmplim_curr_jitter = inc; } } if (pps == -1) return (-1); if (pps > 0 && V_icmplim_output) log(LOG_NOTICE, "Limiting %s from %jd to %d packets/sec\n", V_icmp_rates[which].descr, (intmax_t )pps, V_icmplim + V_icmplim_curr_jitter); return (0); }