/* * 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_input.c 8.2 (Berkeley) 1/4/94 * $FreeBSD: src/sys/netinet/ip_input.c,v 1.130.2.52 2003/03/07 07:01:28 silby Exp $ */ #define _IP_VHL #include "opt_bootp.h" #include "opt_ipfw.h" #include "opt_ipdn.h" #include "opt_ipdivert.h" #include "opt_ipfilter.h" #include "opt_ipstealth.h" #include "opt_ipsec.h" #include "opt_random_ip_id.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 #ifdef IPSEC #include #include #endif #ifdef FAST_IPSEC #include #include #endif int rsvp_on = 0; static int ip_rsvp_on; struct socket *ip_rsvpd; int ipforwarding = 0; SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW, &ipforwarding, 0, "Enable IP forwarding between interfaces"); static int ipsendredirects = 1; /* XXX */ SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW, &ipsendredirects, 0, "Enable sending IP redirects"); int ip_defttl = IPDEFTTL; SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW, &ip_defttl, 0, "Maximum TTL on IP packets"); static int ip_dosourceroute = 0; SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW, &ip_dosourceroute, 0, "Enable forwarding source routed IP packets"); static int ip_acceptsourceroute = 0; SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute, CTLFLAG_RW, &ip_acceptsourceroute, 0, "Enable accepting source routed IP packets"); static int ip_keepfaith = 0; SYSCTL_INT(_net_inet_ip, IPCTL_KEEPFAITH, keepfaith, CTLFLAG_RW, &ip_keepfaith, 0, "Enable packet capture for FAITH IPv4->IPv6 translater daemon"); static int nipq = 0; /* total # of reass queues */ static int maxnipq; SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragpackets, CTLFLAG_RW, &maxnipq, 0, "Maximum number of IPv4 fragment reassembly queue entries"); static int maxfragsperpacket; SYSCTL_INT(_net_inet_ip, OID_AUTO, maxfragsperpacket, CTLFLAG_RW, &maxfragsperpacket, 0, "Maximum number of IPv4 fragments allowed per packet"); static int ip_sendsourcequench = 0; SYSCTL_INT(_net_inet_ip, OID_AUTO, sendsourcequench, CTLFLAG_RW, &ip_sendsourcequench, 0, "Enable the transmission of source quench packets"); /* * XXX - Setting ip_checkinterface mostly implements the receive side of * the Strong ES model described in RFC 1122, but since the routing table * and transmit implementation do not implement the Strong ES model, * setting this to 1 results in an odd hybrid. * * XXX - ip_checkinterface currently must be disabled if you use ipnat * to translate the destination address to another local interface. * * XXX - ip_checkinterface must be disabled if you add IP aliases * to the loopback interface instead of the interface where the * packets for those addresses are received. */ static int ip_checkinterface = 0; SYSCTL_INT(_net_inet_ip, OID_AUTO, check_interface, CTLFLAG_RW, &ip_checkinterface, 0, "Verify packet arrives on correct interface"); #ifdef DIAGNOSTIC static int ipprintfs = 0; #endif static int ipqmaxlen = IFQ_MAXLEN; extern struct domain inetdomain; extern struct ipprotosw inetsw[]; u_char ip_protox[IPPROTO_MAX]; struct in_ifaddrhead in_ifaddrhead; /* first inet address */ struct in_ifaddrhashhead *in_ifaddrhashtbl; /* inet addr hash table */ u_long in_ifaddrhmask; /* mask for hash table */ SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RW, &ipintrq.ifq_maxlen, 0, "Maximum size of the IP input queue"); SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD, &ipintrq.ifq_drops, 0, "Number of packets dropped from the IP input queue"); struct ipstat ipstat; SYSCTL_STRUCT(_net_inet_ip, IPCTL_STATS, stats, CTLFLAG_RW, &ipstat, ipstat, "IP statistics (struct ipstat, netinet/ip_var.h)"); /* Packet reassembly stuff */ #define IPREASS_NHASH_LOG2 6 #define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2) #define IPREASS_HMASK (IPREASS_NHASH - 1) #define IPREASS_HASH(x,y) \ (((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK) static struct ipq ipq[IPREASS_NHASH]; const int ipintrq_present = 1; #ifdef IPCTL_DEFMTU SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, &ip_mtu, 0, "Default MTU"); #endif #ifdef IPSTEALTH static int ipstealth = 0; SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW, &ipstealth, 0, ""); #endif /* Firewall hooks */ ip_fw_chk_t *ip_fw_chk_ptr; int fw_enable = 1 ; int fw_one_pass = 1; /* Dummynet hooks */ ip_dn_io_t *ip_dn_io_ptr; int (*fr_checkp) __P((struct ip *, int, struct ifnet *, int, struct mbuf **)) = NULL; /* * XXX this is ugly -- the following two global variables are * used to store packet state while it travels through the stack. * Note that the code even makes assumptions on the size and * alignment of fields inside struct ip_srcrt so e.g. adding some * fields will break the code. This needs to be fixed. * * We need to save the IP options in case a protocol wants to respond * to an incoming packet over the same route if the packet got here * using IP source routing. This allows connection establishment and * maintenance when the remote end is on a network that is not known * to us. */ static int ip_nhops = 0; static struct ip_srcrt { struct in_addr dst; /* final destination */ char nop; /* one NOP to align */ char srcopt[IPOPT_OFFSET + 1]; /* OPTVAL, OLEN and OFFSET */ struct in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)]; } ip_srcrt; static void save_rte(u_char *, struct in_addr); static int ip_dooptions(struct mbuf *m, int, struct sockaddr_in *next_hop); static void ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop); static void ip_freef(struct ipq *); static struct mbuf *ip_reass(struct mbuf *, struct ipq *, struct ipq *, u_int32_t *, u_int16_t *); static void ipintr(void); /* * IP initialization: fill in IP protocol switch table. * All protocols not implemented in kernel go to raw IP protocol handler. */ void ip_init() { register struct ipprotosw *pr; register int i; TAILQ_INIT(&in_ifaddrhead); in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask); pr = (struct ipprotosw *)pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW); if (pr == 0) panic("ip_init"); for (i = 0; i < IPPROTO_MAX; i++) ip_protox[i] = pr - inetsw; for (pr = (struct ipprotosw *)inetdomain.dom_protosw; pr < (struct ipprotosw *)inetdomain.dom_protoswNPROTOSW; pr++) if (pr->pr_domain->dom_family == PF_INET && pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) ip_protox[pr->pr_protocol] = pr - inetsw; for (i = 0; i < IPREASS_NHASH; i++) ipq[i].next = ipq[i].prev = &ipq[i]; maxnipq = nmbclusters / 32; maxfragsperpacket = 16; #ifndef RANDOM_IP_ID ip_id = time_second & 0xffff; #endif ipintrq.ifq_maxlen = ipqmaxlen; register_netisr(NETISR_IP, ipintr); } /* * XXX watch out this one. It is perhaps used as a cache for * the most recently used route ? it is cleared in in_addroute() * when a new route is successfully created. */ struct route ipforward_rt; static struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; /* * Ip input routine. Checksum and byte swap header. If fragmented * try to reassemble. Process options. Pass to next level. */ void ip_input(struct mbuf *m) { struct ip *ip; struct ipq *fp; struct in_ifaddr *ia = NULL; struct ifaddr *ifa; int i, hlen, checkif; u_short sum; struct in_addr pkt_dst; u_int32_t divert_info = 0; /* packet divert/tee info */ struct ip_fw_args args; #ifdef FAST_IPSEC struct m_tag *mtag; struct tdb_ident *tdbi; struct secpolicy *sp; int s, error; #endif /* FAST_IPSEC */ args.eh = NULL; args.oif = NULL; args.rule = NULL; args.divert_rule = 0; /* divert cookie */ args.next_hop = NULL; /* Grab info from MT_TAG mbufs prepended to the chain. */ for (; m && m->m_type == MT_TAG; m = m->m_next) { switch(m->_m_tag_id) { default: printf("ip_input: unrecognised MT_TAG tag %d\n", m->_m_tag_id); break; case PACKET_TAG_DUMMYNET: args.rule = ((struct dn_pkt *)m)->rule; break; case PACKET_TAG_DIVERT: args.divert_rule = (int)m->m_hdr.mh_data & 0xffff; break; case PACKET_TAG_IPFORWARD: args.next_hop = (struct sockaddr_in *)m->m_hdr.mh_data; break; } } KASSERT(m != NULL && (m->m_flags & M_PKTHDR) != 0, ("ip_input: no HDR")); if (args.rule) { /* dummynet already filtered us */ ip = mtod(m, struct ip *); hlen = IP_VHL_HL(ip->ip_vhl) << 2; goto iphack ; } ipstat.ips_total++; if (m->m_pkthdr.len < sizeof(struct ip)) goto tooshort; if (m->m_len < sizeof (struct ip) && (m = m_pullup(m, sizeof (struct ip))) == 0) { ipstat.ips_toosmall++; return; } ip = mtod(m, struct ip *); if (IP_VHL_V(ip->ip_vhl) != IPVERSION) { ipstat.ips_badvers++; goto bad; } hlen = IP_VHL_HL(ip->ip_vhl) << 2; if (hlen < sizeof(struct ip)) { /* minimum header length */ ipstat.ips_badhlen++; goto bad; } if (hlen > m->m_len) { if ((m = m_pullup(m, hlen)) == 0) { ipstat.ips_badhlen++; return; } ip = mtod(m, struct ip *); } /* 127/8 must not appear on wire - RFC1122 */ if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET || (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) { if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) { ipstat.ips_badaddr++; goto bad; } } if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) { sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID); } else { if (hlen == sizeof(struct ip)) { sum = in_cksum_hdr(ip); } else { sum = in_cksum(m, hlen); } } if (sum) { ipstat.ips_badsum++; goto bad; } /* * Convert fields to host representation. */ ip->ip_len = ntohs(ip->ip_len); if (ip->ip_len < hlen) { ipstat.ips_badlen++; goto bad; } ip->ip_off = ntohs(ip->ip_off); /* * Check that the amount of data in the buffers * is as at least much as the IP header would have us expect. * Trim mbufs if longer than we expect. * Drop packet if shorter than we expect. */ if (m->m_pkthdr.len < ip->ip_len) { tooshort: ipstat.ips_tooshort++; goto bad; } if (m->m_pkthdr.len > ip->ip_len) { if (m->m_len == m->m_pkthdr.len) { m->m_len = ip->ip_len; m->m_pkthdr.len = ip->ip_len; } else m_adj(m, ip->ip_len - m->m_pkthdr.len); } #if defined(IPSEC) && !defined(IPSEC_FILTERGIF) /* * Bypass packet filtering for packets from a tunnel (gif). */ if (ipsec_gethist(m, NULL)) goto pass; #endif /* * IpHack's section. * Right now when no processing on packet has done * and it is still fresh out of network we do our black * deals with it. * - Firewall: deny/allow/divert * - Xlate: translate packet's addr/port (NAT). * - Pipe: pass pkt through dummynet. * - Wrap: fake packet's addr/port * - Encapsulate: put it in another IP and send out. */ iphack: /* * Check if we want to allow this packet to be processed. * Consider it to be bad if not. */ if (fr_checkp) { struct mbuf *m1 = m; if ((*fr_checkp)(ip, hlen, m->m_pkthdr.rcvif, 0, &m1) || !m1) return; ip = mtod(m = m1, struct ip *); } if (fw_enable && IPFW_LOADED) { /* * If we've been forwarded from the output side, then * skip the firewall a second time */ if (args.next_hop) goto ours; args.m = m; i = ip_fw_chk_ptr(&args); m = args.m; if ( (i & IP_FW_PORT_DENY_FLAG) || m == NULL) { /* drop */ if (m) m_freem(m); return; } ip = mtod(m, struct ip *); /* just in case m changed */ if (i == 0 && args.next_hop == NULL) /* common case */ goto pass; if (DUMMYNET_LOADED && (i & IP_FW_PORT_DYNT_FLAG) != 0) { /* Send packet to the appropriate pipe */ ip_dn_io_ptr(m, i&0xffff, DN_TO_IP_IN, &args); return; } #ifdef IPDIVERT if (i != 0 && (i & IP_FW_PORT_DYNT_FLAG) == 0) { /* Divert or tee packet */ divert_info = i; goto ours; } #endif if (i == 0 && args.next_hop != NULL) goto pass; /* * if we get here, the packet must be dropped */ m_freem(m); return; } pass: /* * Process options and, if not destined for us, * ship it on. ip_dooptions returns 1 when an * error was detected (causing an icmp message * to be sent and the original packet to be freed). */ ip_nhops = 0; /* for source routed packets */ if (hlen > sizeof (struct ip) && ip_dooptions(m, 0, args.next_hop)) return; /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no * matter if it is destined to another node, or whether it is * a multicast one, RSVP wants it! and prevents it from being forwarded * anywhere else. Also checks if the rsvp daemon is running before * grabbing the packet. */ if (rsvp_on && ip->ip_p==IPPROTO_RSVP) goto ours; /* * Check our list of addresses, to see if the packet is for us. * If we don't have any addresses, assume any unicast packet * we receive might be for us (and let the upper layers deal * with it). */ if (TAILQ_EMPTY(&in_ifaddrhead) && (m->m_flags & (M_MCAST|M_BCAST)) == 0) goto ours; /* * Cache the destination address of the packet; this may be * changed by use of 'ipfw fwd'. */ pkt_dst = args.next_hop ? args.next_hop->sin_addr : ip->ip_dst; /* * Enable a consistency check between the destination address * and the arrival interface for a unicast packet (the RFC 1122 * strong ES model) if IP forwarding is disabled and the packet * is not locally generated and the packet is not subject to * 'ipfw fwd'. * * XXX - Checking also should be disabled if the destination * address is ipnat'ed to a different interface. * * XXX - Checking is incompatible with IP aliases added * to the loopback interface instead of the interface where * the packets are received. */ checkif = ip_checkinterface && (ipforwarding == 0) && m->m_pkthdr.rcvif != NULL && ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) && (args.next_hop == NULL); /* * Check for exact addresses in the hash bucket. */ LIST_FOREACH(ia, INADDR_HASH(pkt_dst.s_addr), ia_hash) { /* * If the address matches, verify that the packet * arrived via the correct interface if checking is * enabled. */ if (IA_SIN(ia)->sin_addr.s_addr == pkt_dst.s_addr && (!checkif || ia->ia_ifp == m->m_pkthdr.rcvif)) goto ours; } /* * Check for broadcast addresses. * * Only accept broadcast packets that arrive via the matching * interface. Reception of forwarded directed broadcasts would * be handled via ip_forward() and ether_output() with the loopback * into the stack for SIMPLEX interfaces handled by ether_output(). */ if (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 == pkt_dst.s_addr) goto ours; if (ia->ia_netbroadcast.s_addr == pkt_dst.s_addr) goto ours; #ifdef BOOTP_COMPAT if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY) goto ours; #endif } } if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) { struct in_multi *inm; if (ip_mrouter) { /* * If we are acting as a multicast router, all * incoming multicast packets are passed to the * kernel-level multicast forwarding function. * The packet is returned (relatively) intact; if * ip_mforward() returns a non-zero value, the packet * must be discarded, else it may be accepted below. */ if (ip_mforward && ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) { ipstat.ips_cantforward++; m_freem(m); return; } /* * The process-level routing daemon needs to receive * all multicast IGMP packets, whether or not this * host belongs to their destination groups. */ if (ip->ip_p == IPPROTO_IGMP) goto ours; ipstat.ips_forward++; } /* * See if we belong to the destination multicast group on the * arrival interface. */ IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm); if (inm == NULL) { ipstat.ips_notmember++; m_freem(m); return; } goto ours; } if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST) goto ours; if (ip->ip_dst.s_addr == INADDR_ANY) goto ours; /* * FAITH(Firewall Aided Internet Translator) */ if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { if (ip_keepfaith) { if (ip->ip_p == IPPROTO_TCP || ip->ip_p == IPPROTO_ICMP) goto ours; } m_freem(m); return; } /* * Not for us; forward if possible and desirable. */ if (ipforwarding == 0) { ipstat.ips_cantforward++; m_freem(m); } else { #ifdef IPSEC /* * Enforce inbound IPsec SPD. */ if (ipsec4_in_reject(m, NULL)) { ipsecstat.in_polvio++; goto bad; } #endif /* IPSEC */ #ifdef FAST_IPSEC mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); s = splnet(); if (mtag != NULL) { tdbi = (struct tdb_ident *)(mtag + 1); sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); } else { sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, IP_FORWARDING, &error); } if (sp == NULL) { /* NB: can happen if error */ splx(s); /*XXX error stat???*/ DPRINTF(("ip_input: no SP for forwarding\n")); /*XXX*/ goto bad; } /* * Check security policy against packet attributes. */ error = ipsec_in_reject(sp, m); KEY_FREESP(&sp); splx(s); if (error) { ipstat.ips_cantforward++; goto bad; } #endif /* FAST_IPSEC */ ip_forward(m, 0, args.next_hop); } return; ours: #ifdef IPSTEALTH /* * IPSTEALTH: Process non-routing options only * if the packet is destined for us. */ if (ipstealth && hlen > sizeof (struct ip) && ip_dooptions(m, 1, args.next_hop)) return; #endif /* IPSTEALTH */ /* Count the packet in the ip address stats */ if (ia != NULL) { ia->ia_ifa.if_ipackets++; ia->ia_ifa.if_ibytes += m->m_pkthdr.len; } /* * If offset or IP_MF are set, must reassemble. * Otherwise, nothing need be done. * (We could look in the reassembly queue to see * if the packet was previously fragmented, * but it's not worth the time; just let them time out.) */ if (ip->ip_off & (IP_MF | IP_OFFMASK)) { /* If maxnipq is 0, never accept fragments. */ if (maxnipq == 0) { ipstat.ips_fragments++; ipstat.ips_fragdropped++; goto bad; } sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); /* * Look for queue of fragments * of this datagram. */ for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next) if (ip->ip_id == fp->ipq_id && ip->ip_src.s_addr == fp->ipq_src.s_addr && ip->ip_dst.s_addr == fp->ipq_dst.s_addr && ip->ip_p == fp->ipq_p) goto found; fp = 0; /* * Enforce upper bound on number of fragmented packets * for which we attempt reassembly; * If maxnipq is -1, accept all fragments without limitation. */ if ((nipq > maxnipq) && (maxnipq > 0)) { /* * drop something from the tail of the current queue * before proceeding further */ if (ipq[sum].prev == &ipq[sum]) { /* gak */ for (i = 0; i < IPREASS_NHASH; i++) { if (ipq[i].prev != &ipq[i]) { ipstat.ips_fragtimeout += ipq[i].prev->ipq_nfrags; ip_freef(ipq[i].prev); break; } } } else { ipstat.ips_fragtimeout += ipq[sum].prev->ipq_nfrags; ip_freef(ipq[sum].prev); } } found: /* * Adjust ip_len to not reflect header, * convert offset of this to bytes. */ ip->ip_len -= hlen; if (ip->ip_off & IP_MF) { /* * Make sure that fragments have a data length * that's a non-zero multiple of 8 bytes. */ if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) { ipstat.ips_toosmall++; /* XXX */ goto bad; } m->m_flags |= M_FRAG; } else m->m_flags &= ~M_FRAG; ip->ip_off <<= 3; /* * Attempt reassembly; if it succeeds, proceed. * ip_reass() will return a different mbuf, and update * the divert info in divert_info and args.divert_rule. */ ipstat.ips_fragments++; m->m_pkthdr.header = ip; m = ip_reass(m, fp, &ipq[sum], &divert_info, &args.divert_rule); if (m == 0) return; ipstat.ips_reassembled++; ip = mtod(m, struct ip *); /* Get the header length of the reassembled packet */ hlen = IP_VHL_HL(ip->ip_vhl) << 2; #ifdef IPDIVERT /* Restore original checksum before diverting packet */ if (divert_info != 0) { ip->ip_len += hlen; ip->ip_len = htons(ip->ip_len); ip->ip_off = htons(ip->ip_off); ip->ip_sum = 0; if (hlen == sizeof(struct ip)) ip->ip_sum = in_cksum_hdr(ip); else ip->ip_sum = in_cksum(m, hlen); ip->ip_off = ntohs(ip->ip_off); ip->ip_len = ntohs(ip->ip_len); ip->ip_len -= hlen; } #endif } else ip->ip_len -= hlen; #ifdef IPDIVERT /* * Divert or tee packet to the divert protocol if required. */ if (divert_info != 0) { struct mbuf *clone = NULL; /* Clone packet if we're doing a 'tee' */ if ((divert_info & IP_FW_PORT_TEE_FLAG) != 0) clone = m_dup(m, M_DONTWAIT); /* Restore packet header fields to original values */ ip->ip_len += hlen; ip->ip_len = htons(ip->ip_len); ip->ip_off = htons(ip->ip_off); /* Deliver packet to divert input routine */ divert_packet(m, 1, divert_info & 0xffff, args.divert_rule); ipstat.ips_delivered++; /* If 'tee', continue with original packet */ if (clone == NULL) return; m = clone; ip = mtod(m, struct ip *); ip->ip_len += hlen; /* * Jump backwards to complete processing of the * packet. But first clear divert_info to avoid * entering this block again. * We do not need to clear args.divert_rule * or args.next_hop as they will not be used. */ divert_info = 0; goto pass; } #endif #ifdef IPSEC /* * enforce IPsec policy checking if we are seeing last header. * note that we do not visit this with protocols with pcb layer * code - like udp/tcp/raw ip. */ if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 && ipsec4_in_reject(m, NULL)) { ipsecstat.in_polvio++; goto bad; } #endif #if FAST_IPSEC /* * enforce IPsec policy checking if we are seeing last header. * note that we do not visit this with protocols with pcb layer * code - like udp/tcp/raw ip. */ if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) { /* * Check if the packet has already had IPsec processing * done. If so, then just pass it along. This tag gets * set during AH, ESP, etc. input handling, before the * packet is returned to the ip input queue for delivery. */ mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); s = splnet(); if (mtag != NULL) { tdbi = (struct tdb_ident *)(mtag + 1); sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND); } else { sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND, IP_FORWARDING, &error); } if (sp != NULL) { /* * Check security policy against packet attributes. */ error = ipsec_in_reject(sp, m); KEY_FREESP(&sp); } else { /* XXX error stat??? */ error = EINVAL; DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/ goto bad; } splx(s); if (error) goto bad; } #endif /* FAST_IPSEC */ /* * Switch out to protocol's input routine. */ ipstat.ips_delivered++; if (args.next_hop && ip->ip_p == IPPROTO_TCP) { /* TCP needs IPFORWARD info if available */ struct m_hdr tag; tag.mh_type = MT_TAG; tag.mh_flags = PACKET_TAG_IPFORWARD; tag.mh_data = (caddr_t)args.next_hop; tag.mh_next = m; (*inetsw[ip_protox[ip->ip_p]].pr_input)( (struct mbuf *)&tag, hlen, ip->ip_p); } else (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, ip->ip_p); return; bad: m_freem(m); } /* * IP software interrupt routine - to go away sometime soon */ static void ipintr(void) { int s; struct mbuf *m; while(1) { s = splimp(); IF_DEQUEUE(&ipintrq, m); splx(s); if (m == 0) return; ip_input(m); } } /* * Take incoming datagram fragment and try to reassemble it into * whole datagram. If a chain for reassembly of this datagram already * exists, then it is given as fp; otherwise have to make a chain. * * When IPDIVERT enabled, keep additional state with each packet that * tells us if we need to divert or tee the packet we're building. * In particular, *divinfo includes the port and TEE flag, * *divert_rule is the number of the matching rule. */ static struct mbuf * ip_reass(struct mbuf *m, struct ipq *fp, struct ipq *where, u_int32_t *divinfo, u_int16_t *divert_rule) { struct ip *ip = mtod(m, struct ip *); register struct mbuf *p = 0, *q, *nq; struct mbuf *t; int hlen = IP_VHL_HL(ip->ip_vhl) << 2; int i, next; /* * Presence of header sizes in mbufs * would confuse code below. */ m->m_data += hlen; m->m_len -= hlen; /* * If first fragment to arrive, create a reassembly queue. */ if (fp == 0) { if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) goto dropfrag; fp = mtod(t, struct ipq *); insque(fp, where); nipq++; fp->ipq_nfrags = 1; fp->ipq_ttl = IPFRAGTTL; fp->ipq_p = ip->ip_p; fp->ipq_id = ip->ip_id; fp->ipq_src = ip->ip_src; fp->ipq_dst = ip->ip_dst; fp->ipq_frags = m; m->m_nextpkt = NULL; #ifdef IPDIVERT fp->ipq_div_info = 0; fp->ipq_div_cookie = 0; #endif goto inserted; } else { fp->ipq_nfrags++; } #define GETIP(m) ((struct ip*)((m)->m_pkthdr.header)) /* * Find a segment which begins after this one does. */ for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) if (GETIP(q)->ip_off > ip->ip_off) break; /* * If there is a preceding segment, it may provide some of * our data already. If so, drop the data from the incoming * segment. If it provides all of our data, drop us, otherwise * stick new segment in the proper place. * * If some of the data is dropped from the the preceding * segment, then it's checksum is invalidated. */ if (p) { i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off; if (i > 0) { if (i >= ip->ip_len) goto dropfrag; m_adj(m, i); m->m_pkthdr.csum_flags = 0; ip->ip_off += i; ip->ip_len -= i; } m->m_nextpkt = p->m_nextpkt; p->m_nextpkt = m; } else { m->m_nextpkt = fp->ipq_frags; fp->ipq_frags = m; } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off; q = nq) { i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off; if (i < GETIP(q)->ip_len) { GETIP(q)->ip_len -= i; GETIP(q)->ip_off += i; m_adj(q, i); q->m_pkthdr.csum_flags = 0; break; } nq = q->m_nextpkt; m->m_nextpkt = nq; ipstat.ips_fragdropped++; fp->ipq_nfrags--; m_freem(q); } inserted: #ifdef IPDIVERT /* * Transfer firewall instructions to the fragment structure. * Only trust info in the fragment at offset 0. */ if (ip->ip_off == 0) { fp->ipq_div_info = *divinfo; fp->ipq_div_cookie = *divert_rule; } *divinfo = 0; *divert_rule = 0; #endif /* * Check for complete reassembly and perform frag per packet * limiting. * * Frag limiting is performed here so that the nth frag has * a chance to complete the packet before we drop the packet. * As a result, n+1 frags are actually allowed per packet, but * only n will ever be stored. (n = maxfragsperpacket.) * */ next = 0; for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt) { if (GETIP(q)->ip_off != next) { if (fp->ipq_nfrags > maxfragsperpacket) { ipstat.ips_fragdropped += fp->ipq_nfrags; ip_freef(fp); } return (0); } next += GETIP(q)->ip_len; } /* Make sure the last packet didn't have the IP_MF flag */ if (p->m_flags & M_FRAG) { if (fp->ipq_nfrags > maxfragsperpacket) { ipstat.ips_fragdropped += fp->ipq_nfrags; ip_freef(fp); } return (0); } /* * Reassembly is complete. Make sure the packet is a sane size. */ q = fp->ipq_frags; ip = GETIP(q); if (next + (IP_VHL_HL(ip->ip_vhl) << 2) > IP_MAXPACKET) { ipstat.ips_toolong++; ipstat.ips_fragdropped += fp->ipq_nfrags; ip_freef(fp); return (0); } /* * Concatenate fragments. */ m = q; t = m->m_next; m->m_next = 0; m_cat(m, t); nq = q->m_nextpkt; q->m_nextpkt = 0; for (q = nq; q != NULL; q = nq) { nq = q->m_nextpkt; q->m_nextpkt = NULL; m->m_pkthdr.csum_flags &= q->m_pkthdr.csum_flags; m->m_pkthdr.csum_data += q->m_pkthdr.csum_data; m_cat(m, q); } #ifdef IPDIVERT /* * Extract firewall instructions from the fragment structure. */ *divinfo = fp->ipq_div_info; *divert_rule = fp->ipq_div_cookie; #endif /* * Create header for new ip packet by * modifying header of first packet; * dequeue and discard fragment reassembly header. * Make header visible. */ ip->ip_len = next; ip->ip_src = fp->ipq_src; ip->ip_dst = fp->ipq_dst; remque(fp); nipq--; (void) m_free(dtom(fp)); m->m_len += (IP_VHL_HL(ip->ip_vhl) << 2); m->m_data -= (IP_VHL_HL(ip->ip_vhl) << 2); /* some debugging cruft by sklower, below, will go away soon */ if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ register int plen = 0; for (t = m; t; t = t->m_next) plen += t->m_len; m->m_pkthdr.len = plen; } return (m); dropfrag: #ifdef IPDIVERT *divinfo = 0; *divert_rule = 0; #endif ipstat.ips_fragdropped++; if (fp != 0) fp->ipq_nfrags--; m_freem(m); return (0); #undef GETIP } /* * Free a fragment reassembly header and all * associated datagrams. */ static void ip_freef(fp) struct ipq *fp; { register struct mbuf *q; while (fp->ipq_frags) { q = fp->ipq_frags; fp->ipq_frags = q->m_nextpkt; m_freem(q); } remque(fp); (void) m_free(dtom(fp)); nipq--; } /* * IP timer processing; * if a timer expires on a reassembly * queue, discard it. */ void ip_slowtimo() { register struct ipq *fp; int s = splnet(); int i; for (i = 0; i < IPREASS_NHASH; i++) { fp = ipq[i].next; if (fp == 0) continue; while (fp != &ipq[i]) { --fp->ipq_ttl; fp = fp->next; if (fp->prev->ipq_ttl == 0) { ipstat.ips_fragtimeout += fp->prev->ipq_nfrags; ip_freef(fp->prev); } } } /* * If we are over the maximum number of fragments * (due to the limit being lowered), drain off * enough to get down to the new limit. */ if (maxnipq >= 0 && nipq > maxnipq) { for (i = 0; i < IPREASS_NHASH; i++) { while (nipq > maxnipq && (ipq[i].next != &ipq[i])) { ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags; ip_freef(ipq[i].next); } } } ipflow_slowtimo(); splx(s); } /* * Drain off all datagram fragments. */ void ip_drain() { int i; for (i = 0; i < IPREASS_NHASH; i++) { while (ipq[i].next != &ipq[i]) { ipstat.ips_fragdropped += ipq[i].next->ipq_nfrags; ip_freef(ipq[i].next); } } in_rtqdrain(); } /* * Do option processing on a datagram, * possibly discarding it if bad options are encountered, * or forwarding it if source-routed. * The pass argument is used when operating in the IPSTEALTH * mode to tell what options to process: * [LS]SRR (pass 0) or the others (pass 1). * The reason for as many as two passes is that when doing IPSTEALTH, * non-routing options should be processed only if the packet is for us. * Returns 1 if packet has been forwarded/freed, * 0 if the packet should be processed further. */ static int ip_dooptions(struct mbuf *m, int pass, struct sockaddr_in *next_hop) { struct ip *ip = mtod(m, struct ip *); u_char *cp; struct in_ifaddr *ia; int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; struct in_addr *sin, dst; n_time ntime; dst = ip->ip_dst; cp = (u_char *)(ip + 1); cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip); for (; cnt > 0; cnt -= optlen, cp += optlen) { opt = cp[IPOPT_OPTVAL]; if (opt == IPOPT_EOL) break; if (opt == IPOPT_NOP) optlen = 1; else { if (cnt < IPOPT_OLEN + sizeof(*cp)) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } optlen = cp[IPOPT_OLEN]; if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } } switch (opt) { default: break; /* * Source routing with record. * Find interface with current destination address. * If none on this machine then drop if strictly routed, * or do nothing if loosely routed. * Record interface address and bring up next address * component. If strictly routed make sure next * address is on directly accessible net. */ case IPOPT_LSRR: case IPOPT_SSRR: #ifdef IPSTEALTH if (ipstealth && pass > 0) break; #endif if (optlen < IPOPT_OFFSET + sizeof(*cp)) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = ip->ip_dst; ia = (struct in_ifaddr *) ifa_ifwithaddr((struct sockaddr *)&ipaddr); if (ia == 0) { if (opt == IPOPT_SSRR) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } if (!ip_dosourceroute) goto nosourcerouting; /* * Loose routing, and not at next destination * yet; nothing to do except forward. */ break; } off--; /* 0 origin */ if (off > optlen - (int)sizeof(struct in_addr)) { /* * End of source route. Should be for us. */ if (!ip_acceptsourceroute) goto nosourcerouting; save_rte(cp, ip->ip_src); break; } #ifdef IPSTEALTH if (ipstealth) goto dropit; #endif if (!ip_dosourceroute) { if (ipforwarding) { char buf[16]; /* aaa.bbb.ccc.ddd\0 */ /* * Acting as a router, so generate ICMP */ nosourcerouting: strcpy(buf, inet_ntoa(ip->ip_dst)); log(LOG_WARNING, "attempted source route from %s to %s\n", inet_ntoa(ip->ip_src), buf); type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } else { /* * Not acting as a router, so silently drop. */ #ifdef IPSTEALTH dropit: #endif ipstat.ips_cantforward++; m_freem(m); return (1); } } /* * locate outgoing interface */ (void)memcpy(&ipaddr.sin_addr, cp + off, sizeof(ipaddr.sin_addr)); if (opt == IPOPT_SSRR) { #define INA struct in_ifaddr * #define SA struct sockaddr * if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0) ia = (INA)ifa_ifwithnet((SA)&ipaddr); } else ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt); if (ia == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } ip->ip_dst = ipaddr.sin_addr; (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); /* * Let ip_intr's mcast routing check handle mcast pkts */ forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr)); break; case IPOPT_RR: #ifdef IPSTEALTH if (ipstealth && pass == 0) break; #endif if (optlen < IPOPT_OFFSET + sizeof(*cp)) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } /* * If no space remains, ignore. */ off--; /* 0 origin */ if (off > optlen - (int)sizeof(struct in_addr)) break; (void)memcpy(&ipaddr.sin_addr, &ip->ip_dst, sizeof(ipaddr.sin_addr)); /* * locate outgoing interface; if we're the destination, * use the incoming interface (should be same). */ if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 && (ia = ip_rtaddr(ipaddr.sin_addr, &ipforward_rt)) == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; goto bad; } (void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); break; case IPOPT_TS: #ifdef IPSTEALTH if (ipstealth && pass == 0) break; #endif code = cp - (u_char *)ip; if (optlen < 4 || optlen > 40) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if ((off = cp[IPOPT_OFFSET]) < 5) { code = &cp[IPOPT_OLEN] - (u_char *)ip; goto bad; } if (off > optlen - (int)sizeof(int32_t)) { cp[IPOPT_OFFSET + 1] += (1 << 4); if ((cp[IPOPT_OFFSET + 1] & 0xf0) == 0) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } break; } off--; /* 0 origin */ sin = (struct in_addr *)(cp + off); switch (cp[IPOPT_OFFSET + 1] & 0x0f) { case IPOPT_TS_TSONLY: break; case IPOPT_TS_TSANDADDR: if (off + sizeof(n_time) + sizeof(struct in_addr) > optlen) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } ipaddr.sin_addr = dst; ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, m->m_pkthdr.rcvif); if (ia == 0) continue; (void)memcpy(sin, &IA_SIN(ia)->sin_addr, sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); off += sizeof(struct in_addr); break; case IPOPT_TS_PRESPEC: if (off + sizeof(n_time) + sizeof(struct in_addr) > optlen) { code = &cp[IPOPT_OFFSET] - (u_char *)ip; goto bad; } (void)memcpy(&ipaddr.sin_addr, sin, sizeof(struct in_addr)); if (ifa_ifwithaddr((SA)&ipaddr) == 0) continue; cp[IPOPT_OFFSET] += sizeof(struct in_addr); off += sizeof(struct in_addr); break; default: code = &cp[IPOPT_OFFSET + 1] - (u_char *)ip; goto bad; } ntime = iptime(); (void)memcpy(cp + off, &ntime, sizeof(n_time)); cp[IPOPT_OFFSET] += sizeof(n_time); } } if (forward && ipforwarding) { ip_forward(m, 1, next_hop); return (1); } return (0); bad: icmp_error(m, type, code, 0, 0); ipstat.ips_badoptions++; return (1); } /* * Given address of next destination (final or next hop), * return internet address info of interface to be used to get there. */ struct in_ifaddr * ip_rtaddr(dst, rt) struct in_addr dst; struct route *rt; { register struct sockaddr_in *sin; sin = (struct sockaddr_in *)&rt->ro_dst; if (rt->ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) { if (rt->ro_rt) { RTFREE(rt->ro_rt); rt->ro_rt = 0; } sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = dst; rtalloc_ign(rt, RTF_PRCLONING); } if (rt->ro_rt == 0) return ((struct in_ifaddr *)0); return (ifatoia(rt->ro_rt->rt_ifa)); } /* * Save incoming source route for use in replies, * to be picked up later by ip_srcroute if the receiver is interested. */ void save_rte(option, dst) u_char *option; struct in_addr dst; { unsigned olen; olen = option[IPOPT_OLEN]; #ifdef DIAGNOSTIC if (ipprintfs) printf("save_rte: olen %d\n", olen); #endif if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) return; bcopy(option, ip_srcrt.srcopt, olen); ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); ip_srcrt.dst = dst; } /* * Retrieve incoming source route for use in replies, * in the same form used by setsockopt. * The first hop is placed before the options, will be removed later. */ struct mbuf * ip_srcroute() { register struct in_addr *p, *q; register struct mbuf *m; if (ip_nhops == 0) return ((struct mbuf *)0); m = m_get(M_DONTWAIT, MT_HEADER); if (m == 0) return ((struct mbuf *)0); #define OPTSIZ (sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt)) /* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */ m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) + OPTSIZ; #ifdef DIAGNOSTIC if (ipprintfs) printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len); #endif /* * First save first hop for return route */ p = &ip_srcrt.route[ip_nhops - 1]; *(mtod(m, struct in_addr *)) = *p--; #ifdef DIAGNOSTIC if (ipprintfs) printf(" hops %lx", (u_long)ntohl(mtod(m, struct in_addr *)->s_addr)); #endif /* * Copy option fields and padding (nop) to mbuf. */ ip_srcrt.nop = IPOPT_NOP; ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF; (void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr), &ip_srcrt.nop, OPTSIZ); q = (struct in_addr *)(mtod(m, caddr_t) + sizeof(struct in_addr) + OPTSIZ); #undef OPTSIZ /* * Record return path as an IP source route, * reversing the path (pointers are now aligned). */ while (p >= ip_srcrt.route) { #ifdef DIAGNOSTIC if (ipprintfs) printf(" %lx", (u_long)ntohl(q->s_addr)); #endif *q++ = *p--; } /* * Last hop goes to final destination. */ *q = ip_srcrt.dst; #ifdef DIAGNOSTIC if (ipprintfs) printf(" %lx\n", (u_long)ntohl(q->s_addr)); #endif return (m); } /* * Strip out IP options, at higher * level protocol in the kernel. * Second argument is buffer to which options * will be moved, and return value is their length. * XXX should be deleted; last arg currently ignored. */ void ip_stripoptions(m, mopt) register struct mbuf *m; struct mbuf *mopt; { register int i; struct ip *ip = mtod(m, struct ip *); register caddr_t opts; int olen; olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip); opts = (caddr_t)(ip + 1); i = m->m_len - (sizeof (struct ip) + olen); bcopy(opts + olen, opts, (unsigned)i); m->m_len -= olen; if (m->m_flags & M_PKTHDR) m->m_pkthdr.len -= olen; ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2); } u_char inetctlerrmap[PRC_NCMDS] = { 0, 0, 0, 0, 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, EMSGSIZE, EHOSTUNREACH, 0, 0, 0, 0, 0, 0, ENOPROTOOPT, ECONNREFUSED }; /* * Forward a packet. If some error occurs return the sender * an icmp packet. Note we can't always generate a meaningful * icmp message because icmp doesn't have a large enough repertoire * of codes and types. * * If not forwarding, just drop the packet. This could be confusing * if ipforwarding was zero but some routing protocol was advancing * us as a gateway to somewhere. However, we must let the routing * protocol deal with that. * * The srcrt parameter indicates whether the packet is being forwarded * via a source route. */ static void ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop) { struct ip *ip = mtod(m, struct ip *); struct sockaddr_in *sin; struct rtentry *rt; int error, type = 0, code = 0; struct mbuf *mcopy; n_long dest; struct in_addr pkt_dst; struct ifnet *destifp; #if defined(IPSEC) || defined(FAST_IPSEC) struct ifnet dummyifp; #endif dest = 0; /* * Cache the destination address of the packet; this may be * changed by use of 'ipfw fwd'. */ pkt_dst = next_hop ? next_hop->sin_addr : ip->ip_dst; #ifdef DIAGNOSTIC if (ipprintfs) printf("forward: src %lx dst %lx ttl %x\n", (u_long)ip->ip_src.s_addr, (u_long)pkt_dst.s_addr, ip->ip_ttl); #endif if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(pkt_dst) == 0) { ipstat.ips_cantforward++; m_freem(m); return; } #ifdef IPSTEALTH if (!ipstealth) { #endif if (ip->ip_ttl <= IPTTLDEC) { icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); return; } #ifdef IPSTEALTH } #endif sin = (struct sockaddr_in *)&ipforward_rt.ro_dst; if ((rt = ipforward_rt.ro_rt) == 0 || pkt_dst.s_addr != sin->sin_addr.s_addr) { if (ipforward_rt.ro_rt) { RTFREE(ipforward_rt.ro_rt); ipforward_rt.ro_rt = 0; } sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = pkt_dst; rtalloc_ign(&ipforward_rt, RTF_PRCLONING); if (ipforward_rt.ro_rt == 0) { icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); return; } rt = ipforward_rt.ro_rt; } /* * Save the IP header and at most 8 bytes of the payload, * in case we need to generate an ICMP message to the src. * * XXX this can be optimized a lot by saving the data in a local * buffer on the stack (72 bytes at most), and only allocating the * mbuf if really necessary. The vast majority of the packets * are forwarded without having to send an ICMP back (either * because unnecessary, or because rate limited), so we are * really we are wasting a lot of work here. * * We don't use m_copy() because it might return a reference * to a shared cluster. Both this function and ip_output() * assume exclusive access to the IP header in `m', so any * data in a cluster may change before we reach icmp_error(). */ MGET(mcopy, M_DONTWAIT, m->m_type); if (mcopy != NULL && !m_dup_pkthdr(mcopy, m, M_DONTWAIT)) { /* * It's probably ok if the pkthdr dup fails (because * the deep copy of the tag chain failed), but for now * be conservative and just discard the copy since * code below may some day want the tags. */ m_free(mcopy); mcopy = NULL; } if (mcopy != NULL) { mcopy->m_len = imin((IP_VHL_HL(ip->ip_vhl) << 2) + 8, (int)ip->ip_len); m_copydata(m, 0, mcopy->m_len, mtod(mcopy, caddr_t)); } #ifdef IPSTEALTH if (!ipstealth) { #endif ip->ip_ttl -= IPTTLDEC; #ifdef IPSTEALTH } #endif /* * If forwarding packet using same interface that it came in on, * perhaps should send a redirect to sender to shortcut a hop. * Only send redirect if source is sending directly to us, * and if packet was not source routed (or has any options). * Also, don't send redirect if forwarding using a default route * or a route modified by a redirect. */ if (rt->rt_ifp == m->m_pkthdr.rcvif && (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 && satosin(rt_key(rt))->sin_addr.s_addr != 0 && ipsendredirects && !srcrt && !next_hop) { #define RTA(rt) ((struct in_ifaddr *)(rt->rt_ifa)) u_long src = ntohl(ip->ip_src.s_addr); if (RTA(rt) && (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) { if (rt->rt_flags & RTF_GATEWAY) dest = satosin(rt->rt_gateway)->sin_addr.s_addr; else dest = pkt_dst.s_addr; /* Router requirements says to only send host redirects */ type = ICMP_REDIRECT; code = ICMP_REDIRECT_HOST; #ifdef DIAGNOSTIC if (ipprintfs) printf("redirect (%d) to %lx\n", code, (u_long)dest); #endif } } { struct m_hdr tag; if (next_hop) { /* Pass IPFORWARD info if available */ tag.mh_type = MT_TAG; tag.mh_flags = PACKET_TAG_IPFORWARD; tag.mh_data = (caddr_t)next_hop; tag.mh_next = m; m = (struct mbuf *)&tag; } error = ip_output(m, (struct mbuf *)0, &ipforward_rt, IP_FORWARDING, 0, NULL); } if (error) ipstat.ips_cantforward++; else { ipstat.ips_forward++; if (type) ipstat.ips_redirectsent++; else { if (mcopy) { ipflow_create(&ipforward_rt, mcopy); m_freem(mcopy); } return; } } if (mcopy == NULL) return; destifp = NULL; switch (error) { case 0: /* forwarded, but need redirect */ /* type, code set above */ break; case ENETUNREACH: /* shouldn't happen, checked above */ case EHOSTUNREACH: case ENETDOWN: case EHOSTDOWN: default: type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; break; case EMSGSIZE: type = ICMP_UNREACH; code = ICMP_UNREACH_NEEDFRAG; #ifdef IPSEC /* * If the packet is routed over IPsec tunnel, tell the * originator the tunnel MTU. * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz * XXX quickhack!!! */ if (ipforward_rt.ro_rt) { struct secpolicy *sp = NULL; int ipsecerror; int ipsechdr; struct route *ro; sp = ipsec4_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, IP_FORWARDING, &ipsecerror); if (sp == NULL) destifp = ipforward_rt.ro_rt->rt_ifp; else { /* count IPsec header size */ ipsechdr = ipsec4_hdrsiz(mcopy, IPSEC_DIR_OUTBOUND, NULL); /* * find the correct route for outer IPv4 * header, compute tunnel MTU. * * XXX BUG ALERT * The "dummyifp" code relies upon the fact * that icmp_error() touches only ifp->if_mtu. */ /*XXX*/ destifp = NULL; if (sp->req != NULL && sp->req->sav != NULL && sp->req->sav->sah != NULL) { ro = &sp->req->sav->sah->sa_route; if (ro->ro_rt && ro->ro_rt->rt_ifp) { dummyifp.if_mtu = ro->ro_rt->rt_ifp->if_mtu; dummyifp.if_mtu -= ipsechdr; destifp = &dummyifp; } } key_freesp(sp); } } #elif FAST_IPSEC /* * If the packet is routed over IPsec tunnel, tell the * originator the tunnel MTU. * tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz * XXX quickhack!!! */ if (ipforward_rt.ro_rt) { struct secpolicy *sp = NULL; int ipsecerror; int ipsechdr; struct route *ro; sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, IP_FORWARDING, &ipsecerror); if (sp == NULL) destifp = ipforward_rt.ro_rt->rt_ifp; else { /* count IPsec header size */ ipsechdr = ipsec4_hdrsiz(mcopy, IPSEC_DIR_OUTBOUND, NULL); /* * find the correct route for outer IPv4 * header, compute tunnel MTU. * * XXX BUG ALERT * The "dummyifp" code relies upon the fact * that icmp_error() touches only ifp->if_mtu. */ /*XXX*/ destifp = NULL; if (sp->req != NULL && sp->req->sav != NULL && sp->req->sav->sah != NULL) { ro = &sp->req->sav->sah->sa_route; if (ro->ro_rt && ro->ro_rt->rt_ifp) { dummyifp.if_mtu = ro->ro_rt->rt_ifp->if_mtu; dummyifp.if_mtu -= ipsechdr; destifp = &dummyifp; } } KEY_FREESP(&sp); } } #else /* !IPSEC && !FAST_IPSEC */ if (ipforward_rt.ro_rt) destifp = ipforward_rt.ro_rt->rt_ifp; #endif /*IPSEC*/ ipstat.ips_cantfrag++; break; case ENOBUFS: /* * A router should not generate ICMP_SOURCEQUENCH as * required in RFC1812 Requirements for IP Version 4 Routers. * Source quench could be a big problem under DoS attacks, * or if the underlying interface is rate-limited. * Those who need source quench packets may re-enable them * via the net.inet.ip.sendsourcequench sysctl. */ if (ip_sendsourcequench == 0) { m_freem(mcopy); return; } else { type = ICMP_SOURCEQUENCH; code = 0; } break; case EACCES: /* ipfw denied packet */ m_freem(mcopy); return; } icmp_error(mcopy, type, code, dest, destifp); } void ip_savecontrol(inp, mp, ip, m) register struct inpcb *inp; register struct mbuf **mp; register struct ip *ip; register struct mbuf *m; { if (inp->inp_socket->so_options & SO_TIMESTAMP) { struct timeval tv; microtime(&tv); *mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv), SCM_TIMESTAMP, SOL_SOCKET); if (*mp) mp = &(*mp)->m_next; } if (inp->inp_flags & INP_RECVDSTADDR) { *mp = sbcreatecontrol((caddr_t) &ip->ip_dst, sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP); if (*mp) mp = &(*mp)->m_next; } #ifdef notyet /* XXX * Moving these out of udp_input() made them even more broken * than they already were. */ /* options were tossed already */ if (inp->inp_flags & INP_RECVOPTS) { *mp = sbcreatecontrol((caddr_t) opts_deleted_above, sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP); if (*mp) mp = &(*mp)->m_next; } /* ip_srcroute doesn't do what we want here, need to fix */ if (inp->inp_flags & INP_RECVRETOPTS) { *mp = sbcreatecontrol((caddr_t) ip_srcroute(), sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP); if (*mp) mp = &(*mp)->m_next; } #endif if (inp->inp_flags & INP_RECVIF) { struct ifnet *ifp; struct sdlbuf { struct sockaddr_dl sdl; u_char pad[32]; } sdlbuf; struct sockaddr_dl *sdp; struct sockaddr_dl *sdl2 = &sdlbuf.sdl; if (((ifp = m->m_pkthdr.rcvif)) && ( ifp->if_index && (ifp->if_index <= if_index))) { sdp = (struct sockaddr_dl *)(ifnet_addrs [ifp->if_index - 1]->ifa_addr); /* * Change our mind and don't try copy. */ if ((sdp->sdl_family != AF_LINK) || (sdp->sdl_len > sizeof(sdlbuf))) { goto makedummy; } bcopy(sdp, sdl2, sdp->sdl_len); } else { makedummy: sdl2->sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]); sdl2->sdl_family = AF_LINK; sdl2->sdl_index = 0; sdl2->sdl_nlen = sdl2->sdl_alen = sdl2->sdl_slen = 0; } *mp = sbcreatecontrol((caddr_t) sdl2, sdl2->sdl_len, IP_RECVIF, IPPROTO_IP); if (*mp) mp = &(*mp)->m_next; } } /* * XXX these routines are called from the upper part of the kernel. * * They could also be moved to ip_mroute.c, since all the RSVP * handling is done there already. */ int ip_rsvp_init(struct socket *so) { if (so->so_type != SOCK_RAW || so->so_proto->pr_protocol != IPPROTO_RSVP) return EOPNOTSUPP; if (ip_rsvpd != NULL) return EADDRINUSE; ip_rsvpd = so; /* * This may seem silly, but we need to be sure we don't over-increment * the RSVP counter, in case something slips up. */ if (!ip_rsvp_on) { ip_rsvp_on = 1; rsvp_on++; } return 0; } int ip_rsvp_done(void) { ip_rsvpd = NULL; /* * This may seem silly, but we need to be sure we don't over-decrement * the RSVP counter, in case something slips up. */ if (ip_rsvp_on) { ip_rsvp_on = 0; rsvp_on--; } return 0; } void rsvp_input(struct mbuf *m, int off, int proto) /* XXX must fixup manually */ { if (rsvp_input_p) { /* call the real one if loaded */ rsvp_input_p(m, off, proto); return; } /* Can still get packets with rsvp_on = 0 if there is a local member * of the group to which the RSVP packet is addressed. But in this * case we want to throw the packet away. */ if (!rsvp_on) { m_freem(m); return; } if (ip_rsvpd != NULL) { rip_input(m, off, proto); return; } /* Drop the packet */ m_freem(m); }