/* $OpenBSD: ip_input.c,v 1.129 2005/06/15 07:24:05 markus Exp $ */ /* $NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $ */ /* * 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_input.c 8.2 (Berkeley) 1/4/94 */ #include "pf.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if NPF > 0 #include #endif #ifdef IPSEC #include #endif /* IPSEC */ #define IPMTUDISCTIMEOUT (10 * 60) /* as per RFC 1191 */ struct ipqhead ipq; int encdebug = 0; int ipsec_keep_invalid = IPSEC_DEFAULT_EMBRYONIC_SA_TIMEOUT; int ipsec_require_pfs = IPSEC_DEFAULT_PFS; int ipsec_soft_allocations = IPSEC_DEFAULT_SOFT_ALLOCATIONS; int ipsec_exp_allocations = IPSEC_DEFAULT_EXP_ALLOCATIONS; int ipsec_soft_bytes = IPSEC_DEFAULT_SOFT_BYTES; int ipsec_exp_bytes = IPSEC_DEFAULT_EXP_BYTES; int ipsec_soft_timeout = IPSEC_DEFAULT_SOFT_TIMEOUT; int ipsec_exp_timeout = IPSEC_DEFAULT_EXP_TIMEOUT; int ipsec_soft_first_use = IPSEC_DEFAULT_SOFT_FIRST_USE; int ipsec_exp_first_use = IPSEC_DEFAULT_EXP_FIRST_USE; int ipsec_expire_acquire = IPSEC_DEFAULT_EXPIRE_ACQUIRE; char ipsec_def_enc[20]; char ipsec_def_auth[20]; char ipsec_def_comp[20]; /* values controllable via sysctl */ int ipforwarding = 0; int ipsendredirects = 1; int ip_dosourceroute = 0; int ip_defttl = IPDEFTTL; int ip_mtudisc = 1; u_int ip_mtudisc_timeout = IPMTUDISCTIMEOUT; int ip_directedbcast = 0; #ifdef DIAGNOSTIC int ipprintfs = 0; #endif struct rttimer_queue *ip_mtudisc_timeout_q = NULL; int ipsec_auth_default_level = IPSEC_AUTH_LEVEL_DEFAULT; int ipsec_esp_trans_default_level = IPSEC_ESP_TRANS_LEVEL_DEFAULT; int ipsec_esp_network_default_level = IPSEC_ESP_NETWORK_LEVEL_DEFAULT; int ipsec_ipcomp_default_level = IPSEC_IPCOMP_LEVEL_DEFAULT; /* Keep track of memory used for reassembly */ int ip_maxqueue = 300; int ip_frags = 0; /* from in_pcb.c */ extern int ipport_firstauto; extern int ipport_lastauto; extern int ipport_hifirstauto; extern int ipport_hilastauto; extern struct baddynamicports baddynamicports; int *ipctl_vars[IPCTL_MAXID] = IPCTL_VARS; extern struct domain inetdomain; extern struct protosw inetsw[]; u_char ip_protox[IPPROTO_MAX]; int ipqmaxlen = IFQ_MAXLEN; struct in_ifaddrhead in_ifaddr; struct ifqueue ipintrq; int ipq_locked; static __inline int ipq_lock_try(void); static __inline void ipq_unlock(void); struct pool ipqent_pool; struct ipstat ipstat; static __inline int ipq_lock_try() { int s; s = splimp(); if (ipq_locked) { splx(s); return (0); } ipq_locked = 1; splx(s); return (1); } #define ipq_lock() ipq_lock_try() static __inline void ipq_unlock() { int s; s = splimp(); ipq_locked = 0; splx(s); } char * inet_ntoa(ina) struct in_addr ina; { static char buf[4*sizeof "123"]; unsigned char *ucp = (unsigned char *)&ina; snprintf(buf, sizeof buf, "%d.%d.%d.%d", ucp[0] & 0xff, ucp[1] & 0xff, ucp[2] & 0xff, ucp[3] & 0xff); return (buf); } /* * 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. */ 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_weadvertise(u_int32_t); /* * IP initialization: fill in IP protocol switch table. * All protocols not implemented in kernel go to raw IP protocol handler. */ void ip_init() { struct protosw *pr; int i; const u_int16_t defbaddynamicports_tcp[] = DEFBADDYNAMICPORTS_TCP; const u_int16_t defbaddynamicports_udp[] = DEFBADDYNAMICPORTS_UDP; pool_init(&ipqent_pool, sizeof(struct ipqent), 0, 0, 0, "ipqepl", NULL); pr = 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 = inetdomain.dom_protosw; pr < 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; LIST_INIT(&ipq); ipintrq.ifq_maxlen = ipqmaxlen; TAILQ_INIT(&in_ifaddr); if (ip_mtudisc != 0) ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout); /* Fill in list of ports not to allocate dynamically. */ bzero((void *)&baddynamicports, sizeof(baddynamicports)); for (i = 0; defbaddynamicports_tcp[i] != 0; i++) DP_SET(baddynamicports.tcp, defbaddynamicports_tcp[i]); for (i = 0; defbaddynamicports_udp[i] != 0; i++) DP_SET(baddynamicports.udp, defbaddynamicports_tcp[i]); strlcpy(ipsec_def_enc, IPSEC_DEFAULT_DEF_ENC, sizeof(ipsec_def_enc)); strlcpy(ipsec_def_auth, IPSEC_DEFAULT_DEF_AUTH, sizeof(ipsec_def_auth)); strlcpy(ipsec_def_comp, IPSEC_DEFAULT_DEF_COMP, sizeof(ipsec_def_comp)); } struct sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET }; struct route ipforward_rt; void ipintr() { struct mbuf *m; int s; while (1) { /* * Get next datagram off input queue and get IP header * in first mbuf. */ s = splimp(); IF_DEQUEUE(&ipintrq, m); splx(s); if (m == 0) return; #ifdef DIAGNOSTIC if ((m->m_flags & M_PKTHDR) == 0) panic("ipintr no HDR"); #endif ipv4_input(m); } } /* * Ip input routine. Checksum and byte swap header. If fragmented * try to reassemble. Process options. Pass to next level. */ void ipv4_input(m) struct mbuf *m; { struct ip *ip; struct ipq *fp; struct in_ifaddr *ia; struct ipqent *ipqe; int hlen, mff, len; in_addr_t pfrdr = 0; #ifdef IPSEC int error, s; struct tdb *tdb; struct tdb_ident *tdbi; struct m_tag *mtag; #endif /* IPSEC */ /* * If no IP addresses have been set yet but the interfaces * are receiving, can't do anything with incoming packets yet. */ if (in_ifaddr.tqh_first == 0) goto bad; ipstat.ips_total++; if (m->m_len < sizeof (struct ip) && (m = m_pullup(m, sizeof (struct ip))) == NULL) { ipstat.ips_toosmall++; return; } ip = mtod(m, struct ip *); if (ip->ip_v != IPVERSION) { ipstat.ips_badvers++; goto bad; } hlen = ip->ip_hl << 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)) == NULL) { 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 & M_IPV4_CSUM_IN_OK) == 0) { if (m->m_pkthdr.csum_flags & M_IPV4_CSUM_IN_BAD) { ipstat.ips_inhwcsum++; ipstat.ips_badsum++; goto bad; } if (in_cksum(m, hlen) != 0) { ipstat.ips_badsum++; goto bad; } } else { m->m_pkthdr.csum_flags &= ~M_IPV4_CSUM_IN_OK; ipstat.ips_inhwcsum++; } /* Retrieve the packet length. */ len = ntohs(ip->ip_len); /* * Convert fields to host representation. */ if (len < hlen) { ipstat.ips_badlen++; goto bad; } /* * Check that the amount of data in the buffers * is at least as 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 < len) { ipstat.ips_tooshort++; goto bad; } if (m->m_pkthdr.len > len) { if (m->m_len == m->m_pkthdr.len) { m->m_len = len; m->m_pkthdr.len = len; } else m_adj(m, len - m->m_pkthdr.len); } #if NPF > 0 /* * Packet filter */ pfrdr = ip->ip_dst.s_addr; if (pf_test(PF_IN, m->m_pkthdr.rcvif, &m, NULL) != PF_PASS) goto bad; if (m == NULL) return; ip = mtod(m, struct ip *); hlen = ip->ip_hl << 2; pfrdr = (pfrdr != ip->ip_dst.s_addr); #endif /* * 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)) { return; } /* * Check our list of addresses, to see if the packet is for us. */ if ((ia = in_iawithaddr(ip->ip_dst, m)) != NULL && (ia->ia_ifp->if_flags & IFF_UP)) goto ours; if (IN_MULTICAST(ip->ip_dst.s_addr)) { struct in_multi *inm; #ifdef MROUTING extern struct socket *ip_mrouter; if (m->m_flags & M_EXT) { if ((m = m_pullup(m, hlen)) == NULL) { ipstat.ips_toosmall++; return; } ip = mtod(m, struct ip *); } 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. * * (The IP ident field is put in the same byte order * as expected when ip_mforward() is called from * ip_output().) */ if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) { ipstat.ips_cantforward++; m_freem(m); return; } /* * The process-level routing demon 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++; } #endif /* * 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_cantforward++; m_freem(m); return; } goto ours; } if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_dst.s_addr == INADDR_ANY) goto ours; /* * Not for us; forward if possible and desirable. */ if (ipforwarding == 0) { ipstat.ips_cantforward++; m_freem(m); } else { #ifdef IPSEC /* * IPsec policy check for forwarded packets. Look at * inner-most IPsec SA used. */ mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); s = splnet(); if (mtag != NULL) { tdbi = (struct tdb_ident *)(mtag + 1); tdb = gettdb(tdbi->spi, &tdbi->dst, tdbi->proto); } else tdb = NULL; ipsp_spd_lookup(m, AF_INET, hlen, &error, IPSP_DIRECTION_IN, tdb, NULL); splx(s); /* Error or otherwise drop-packet indication */ if (error) { ipstat.ips_cantforward++; m_freem(m); return; } /* * Fall through, forward packet. Outbound IPsec policy * checking will occur in ip_output(). */ #endif /* IPSEC */ ip_forward(m, pfrdr); } return; ours: /* * 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 &~ htons(IP_DF | IP_RF)) { if (m->m_flags & M_EXT) { /* XXX */ if ((m = m_pullup(m, hlen)) == NULL) { ipstat.ips_toosmall++; return; } ip = mtod(m, struct ip *); } /* * Look for queue of fragments * of this datagram. */ ipq_lock(); for (fp = ipq.lh_first; fp != NULL; fp = fp->ipq_q.le_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; found: /* * Adjust ip_len to not reflect header, * set ipqe_mff if more fragments are expected, * convert offset of this to bytes. */ ip->ip_len = htons(ntohs(ip->ip_len) - hlen); mff = (ip->ip_off & htons(IP_MF)) != 0; if (mff) { /* * Make sure that fragments have a data length * that's a non-zero multiple of 8 bytes. */ if (ntohs(ip->ip_len) == 0 || (ntohs(ip->ip_len) & 0x7) != 0) { ipstat.ips_badfrags++; ipq_unlock(); goto bad; } } ip->ip_off = htons(ntohs(ip->ip_off) << 3); /* * If datagram marked as having more fragments * or if this is not the first fragment, * attempt reassembly; if it succeeds, proceed. */ if (mff || ip->ip_off) { ipstat.ips_fragments++; if (ip_frags + 1 > ip_maxqueue) { ip_flush(); ipstat.ips_rcvmemdrop++; ipq_unlock(); goto bad; } ipqe = pool_get(&ipqent_pool, PR_NOWAIT); if (ipqe == NULL) { ipstat.ips_rcvmemdrop++; ipq_unlock(); goto bad; } ip_frags++; ipqe->ipqe_mff = mff; ipqe->ipqe_m = m; ipqe->ipqe_ip = ip; m = ip_reass(ipqe, fp); if (m == 0) { ipq_unlock(); return; } ipstat.ips_reassembled++; ip = mtod(m, struct ip *); hlen = ip->ip_hl << 2; ip->ip_len = htons(ntohs(ip->ip_len) + hlen); } else if (fp) ip_freef(fp); ipq_unlock(); } #ifdef IPSEC /* * If it's a protected packet for us, skip the policy check. * That's because we really only care about the properties of * the protected packet, and not the intermediate versions. * While this is not the most paranoid setting, it allows * some flexibility in handling nested tunnels (in setting up * the policies). */ if ((ip->ip_p == IPPROTO_ESP) || (ip->ip_p == IPPROTO_AH) || (ip->ip_p == IPPROTO_IPCOMP)) goto skipipsec; /* * If the protected packet was tunneled, then we need to * verify the protected packet's information, not the * external headers. Thus, skip the policy lookup for the * external packet, and keep the IPsec information linked on * the packet header (the encapsulation routines know how * to deal with that). */ if ((ip->ip_p == IPPROTO_IPIP) || (ip->ip_p == IPPROTO_IPV6)) goto skipipsec; /* * If the protected packet is TCP or UDP, we'll do the * policy check in the respective input routine, so we can * check for bypass sockets. */ if ((ip->ip_p == IPPROTO_TCP) || (ip->ip_p == IPPROTO_UDP)) goto skipipsec; /* * IPsec policy check for local-delivery packets. Look at the * inner-most SA that protected the packet. This is in fact * a bit too restrictive (it could end up causing packets to * be dropped that semantically follow the policy, e.g., in * certain SA-bundle configurations); but the alternative is * very complicated (and requires keeping track of what * kinds of tunneling headers have been seen in-between the * IPsec headers), and I don't think we lose much functionality * that's needed in the real world (who uses bundles anyway ?). */ mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL); s = splnet(); if (mtag) { tdbi = (struct tdb_ident *)(mtag + 1); tdb = gettdb(tdbi->spi, &tdbi->dst, tdbi->proto); } else tdb = NULL; ipsp_spd_lookup(m, AF_INET, hlen, &error, IPSP_DIRECTION_IN, tdb, NULL); splx(s); /* Error or otherwise drop-packet indication. */ if (error) { ipstat.ips_cantforward++; m_freem(m); return; } skipipsec: /* Otherwise, just fall through and deliver the packet */ #endif /* IPSEC */ /* * Switch out to protocol's input routine. */ ipstat.ips_delivered++; (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen, NULL, 0); return; bad: m_freem(m); } struct in_ifaddr * in_iawithaddr(ina, m) struct in_addr ina; struct mbuf *m; { struct in_ifaddr *ia; TAILQ_FOREACH(ia, &in_ifaddr, ia_list) { if ((ina.s_addr == ia->ia_addr.sin_addr.s_addr) || ((ia->ia_ifp->if_flags & (IFF_LOOPBACK|IFF_LINK1)) == (IFF_LOOPBACK|IFF_LINK1) && ia->ia_subnet == (ina.s_addr & ia->ia_subnetmask))) return ia; if (((ip_directedbcast == 0) || (m && ip_directedbcast && ia->ia_ifp == m->m_pkthdr.rcvif)) && (ia->ia_ifp->if_flags & IFF_BROADCAST)) { if (ina.s_addr == ia->ia_broadaddr.sin_addr.s_addr || ina.s_addr == ia->ia_netbroadcast.s_addr || /* * Look for all-0's host part (old broadcast addr), * either for subnet or net. */ ina.s_addr == ia->ia_subnet || ina.s_addr == ia->ia_net) { /* Make sure M_BCAST is set */ if (m) m->m_flags |= M_BCAST; return ia; } } } return NULL; } /* * 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. */ struct mbuf * ip_reass(ipqe, fp) struct ipqent *ipqe; struct ipq *fp; { struct mbuf *m = ipqe->ipqe_m; struct ipqent *nq, *p, *q; struct ip *ip; struct mbuf *t; int hlen = ipqe->ipqe_ip->ip_hl << 2; int i, next; u_int8_t ecn, ecn0; /* * 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) { MALLOC(fp, struct ipq *, sizeof (struct ipq), M_FTABLE, M_NOWAIT); if (fp == NULL) goto dropfrag; LIST_INSERT_HEAD(&ipq, fp, ipq_q); fp->ipq_ttl = IPFRAGTTL; fp->ipq_p = ipqe->ipqe_ip->ip_p; fp->ipq_id = ipqe->ipqe_ip->ip_id; LIST_INIT(&fp->ipq_fragq); fp->ipq_src = ipqe->ipqe_ip->ip_src; fp->ipq_dst = ipqe->ipqe_ip->ip_dst; p = NULL; goto insert; } /* * Handle ECN by comparing this segment with the first one; * if CE is set, do not lose CE. * drop if CE and not-ECT are mixed for the same packet. */ ecn = ipqe->ipqe_ip->ip_tos & IPTOS_ECN_MASK; ecn0 = fp->ipq_fragq.lh_first->ipqe_ip->ip_tos & IPTOS_ECN_MASK; if (ecn == IPTOS_ECN_CE) { if (ecn0 == IPTOS_ECN_NOTECT) goto dropfrag; if (ecn0 != IPTOS_ECN_CE) fp->ipq_fragq.lh_first->ipqe_ip->ip_tos |= IPTOS_ECN_CE; } if (ecn == IPTOS_ECN_NOTECT && ecn0 != IPTOS_ECN_NOTECT) goto dropfrag; /* * Find a segment which begins after this one does. */ for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL; p = q, q = q->ipqe_q.le_next) if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_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. */ if (p != NULL) { i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) - ntohs(ipqe->ipqe_ip->ip_off); if (i > 0) { if (i >= ntohs(ipqe->ipqe_ip->ip_len)) goto dropfrag; m_adj(ipqe->ipqe_m, i); ipqe->ipqe_ip->ip_off = htons(ntohs(ipqe->ipqe_ip->ip_off) + i); ipqe->ipqe_ip->ip_len = htons(ntohs(ipqe->ipqe_ip->ip_len) - i); } } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ for (; q != NULL && ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) > ntohs(q->ipqe_ip->ip_off); q = nq) { i = (ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off); if (i < ntohs(q->ipqe_ip->ip_len)) { q->ipqe_ip->ip_len = htons(ntohs(q->ipqe_ip->ip_len) - i); q->ipqe_ip->ip_off = htons(ntohs(q->ipqe_ip->ip_off) + i); m_adj(q->ipqe_m, i); break; } nq = q->ipqe_q.le_next; m_freem(q->ipqe_m); LIST_REMOVE(q, ipqe_q); pool_put(&ipqent_pool, q); ip_frags--; } insert: /* * Stick new segment in its place; * check for complete reassembly. */ if (p == NULL) { LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q); } else { LIST_INSERT_AFTER(p, ipqe, ipqe_q); } next = 0; for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL; p = q, q = q->ipqe_q.le_next) { if (ntohs(q->ipqe_ip->ip_off) != next) return (0); next += ntohs(q->ipqe_ip->ip_len); } if (p->ipqe_mff) return (0); /* * Reassembly is complete. Check for a bogus message size and * concatenate fragments. */ q = fp->ipq_fragq.lh_first; ip = q->ipqe_ip; if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) { ipstat.ips_toolong++; ip_freef(fp); return (0); } m = q->ipqe_m; t = m->m_next; m->m_next = 0; m_cat(m, t); nq = q->ipqe_q.le_next; pool_put(&ipqent_pool, q); ip_frags--; for (q = nq; q != NULL; q = nq) { t = q->ipqe_m; nq = q->ipqe_q.le_next; pool_put(&ipqent_pool, q); ip_frags--; m_cat(m, t); } /* * Create header for new ip packet by * modifying header of first packet; * dequeue and discard fragment reassembly header. * Make header visible. */ ip->ip_len = htons(next); ip->ip_src = fp->ipq_src; ip->ip_dst = fp->ipq_dst; LIST_REMOVE(fp, ipq_q); FREE(fp, M_FTABLE); m->m_len += (ip->ip_hl << 2); m->m_data -= (ip->ip_hl << 2); /* some debugging cruft by sklower, below, will go away soon */ if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */ int plen = 0; for (t = m; t; t = t->m_next) plen += t->m_len; m->m_pkthdr.len = plen; } return (m); dropfrag: ipstat.ips_fragdropped++; m_freem(m); pool_put(&ipqent_pool, ipqe); ip_frags--; return (0); } /* * Free a fragment reassembly header and all * associated datagrams. */ void ip_freef(fp) struct ipq *fp; { struct ipqent *q, *p; for (q = fp->ipq_fragq.lh_first; q != NULL; q = p) { p = q->ipqe_q.le_next; m_freem(q->ipqe_m); LIST_REMOVE(q, ipqe_q); pool_put(&ipqent_pool, q); ip_frags--; } LIST_REMOVE(fp, ipq_q); FREE(fp, M_FTABLE); } /* * IP timer processing; * if a timer expires on a reassembly queue, discard it. * clear the forwarding cache, there might be a better route. */ void ip_slowtimo() { struct ipq *fp, *nfp; int s = splsoftnet(); ipq_lock(); for (fp = ipq.lh_first; fp != NULL; fp = nfp) { nfp = fp->ipq_q.le_next; if (--fp->ipq_ttl == 0) { ipstat.ips_fragtimeout++; ip_freef(fp); } } ipq_unlock(); if (ipforward_rt.ro_rt) { RTFREE(ipforward_rt.ro_rt); ipforward_rt.ro_rt = 0; } splx(s); } /* * Drain off all datagram fragments. */ void ip_drain() { if (ipq_lock_try() == 0) return; while (ipq.lh_first != NULL) { ipstat.ips_fragdropped++; ip_freef(ipq.lh_first); } ipq_unlock(); } /* * Flush a bunch of datagram fragments, till we are down to 75%. */ void ip_flush() { int max = 50; /* ipq already locked */ while (ipq.lh_first != NULL && ip_frags > ip_maxqueue * 3 / 4 && --max) { ipstat.ips_fragdropped++; ip_freef(ipq.lh_first); } } /* * Do option processing on a datagram, * possibly discarding it if bad options are encountered, * or forwarding it if source-routed. * Returns 1 if packet has been forwarded/freed, * 0 if the packet should be processed further. */ int ip_dooptions(m) struct mbuf *m; { struct ip *ip = mtod(m, struct ip *); u_char *cp; struct ip_timestamp ipt; 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->ip_hl << 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: if (!ip_dosourceroute) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; 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 = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))); if (ia == 0) { if (opt == IPOPT_SSRR) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } /* * Loose routing, and not at next destination * yet; nothing to do except forward. */ break; } off--; /* 0 origin */ if ((off + sizeof(struct in_addr)) > optlen) { /* * End of source route. Should be for us. */ save_rte(cp, ip->ip_src); break; } /* * locate outgoing interface */ bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr, 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); if (ia == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_SRCFAIL; goto bad; } ip->ip_dst = ipaddr.sin_addr; bcopy((caddr_t)&ia->ia_addr.sin_addr, (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); /* * Let ip_intr's mcast routing check handle mcast pkts */ forward = !IN_MULTICAST(ip->ip_dst.s_addr); break; case IPOPT_RR: 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; } /* * If no space remains, ignore. */ off--; /* 0 origin */ if ((off + sizeof(struct in_addr)) > optlen) break; bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr, 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)) == 0) { type = ICMP_UNREACH; code = ICMP_UNREACH_HOST; goto bad; } bcopy((caddr_t)&ia->ia_addr.sin_addr, (caddr_t)(cp + off), sizeof(struct in_addr)); cp[IPOPT_OFFSET] += sizeof(struct in_addr); break; case IPOPT_TS: code = cp - (u_char *)ip; if (optlen < sizeof(struct ip_timestamp)) goto bad; bcopy(cp, &ipt, sizeof(struct ip_timestamp)); if (ipt.ipt_ptr < 5 || ipt.ipt_len < 5) goto bad; if (ipt.ipt_ptr - 1 + sizeof(n_time) > ipt.ipt_len) { if (++ipt.ipt_oflw == 0) goto bad; break; } bcopy(cp + ipt.ipt_ptr - 1, &sin, sizeof sin); switch (ipt.ipt_flg) { case IPOPT_TS_TSONLY: break; case IPOPT_TS_TSANDADDR: if (ipt.ipt_ptr - 1 + sizeof(n_time) + sizeof(struct in_addr) > ipt.ipt_len) goto bad; ipaddr.sin_addr = dst; ia = (INA)ifaof_ifpforaddr((SA)&ipaddr, m->m_pkthdr.rcvif); if (ia == 0) continue; bcopy((caddr_t)&ia->ia_addr.sin_addr, (caddr_t)&sin, sizeof(struct in_addr)); ipt.ipt_ptr += sizeof(struct in_addr); break; case IPOPT_TS_PRESPEC: if (ipt.ipt_ptr - 1 + sizeof(n_time) + sizeof(struct in_addr) > ipt.ipt_len) goto bad; bcopy((caddr_t)&sin, (caddr_t)&ipaddr.sin_addr, sizeof(struct in_addr)); if (ifa_ifwithaddr((SA)&ipaddr) == 0) continue; ipt.ipt_ptr += sizeof(struct in_addr); break; default: /* XXX can't take &ipt->ipt_flg */ code = (u_char *)&ipt.ipt_ptr - (u_char *)ip + 1; goto bad; } ntime = iptime(); bcopy((caddr_t)&ntime, (caddr_t)cp + ipt.ipt_ptr - 1, sizeof(n_time)); ipt.ipt_ptr += sizeof(n_time); } } if (forward && ipforwarding) { ip_forward(m, 1); 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) struct in_addr dst; { struct sockaddr_in *sin; sin = satosin(&ipforward_rt.ro_dst); if (ipforward_rt.ro_rt == 0 || 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 = dst; rtalloc(&ipforward_rt); } if (ipforward_rt.ro_rt == 0) return ((struct in_ifaddr *)0); return (ifatoia(ipforward_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 /* 0 */ if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst))) return; bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen); ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr); ip_srcrt.dst = dst; } /* * Check whether we do proxy ARP for this address and we point to ourselves. * Code shamelessly copied from arplookup(). */ static int ip_weadvertise(addr) u_int32_t addr; { struct rtentry *rt; struct ifnet *ifp; struct ifaddr *ifa; struct sockaddr_inarp sin; sin.sin_len = sizeof(sin); sin.sin_family = AF_INET; sin.sin_addr.s_addr = addr; sin.sin_other = SIN_PROXY; rt = rtalloc1(sintosa(&sin), 0); if (rt == 0) return 0; if ((rt->rt_flags & RTF_GATEWAY) || (rt->rt_flags & RTF_LLINFO) == 0 || rt->rt_gateway->sa_family != AF_LINK) { RTFREE(rt); return 0; } for (ifp = ifnet.tqh_first; ifp != 0; ifp = ifp->if_list.tqe_next) for (ifa = ifp->if_addrlist.tqh_first; ifa != 0; ifa = ifa->ifa_list.tqe_next) { if (ifa->ifa_addr->sa_family != rt->rt_gateway->sa_family) continue; if (!bcmp(LLADDR((struct sockaddr_dl *)ifa->ifa_addr), LLADDR((struct sockaddr_dl *)rt->rt_gateway), ETHER_ADDR_LEN)) { RTFREE(rt); return 1; } } RTFREE(rt); return 0; } /* * 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() { struct in_addr *p, *q; struct mbuf *m; if (ip_nhops == 0) return ((struct mbuf *)0); m = m_get(M_DONTWAIT, MT_SOOPTS); 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 %x", 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; bcopy((caddr_t)&ip_srcrt.nop, mtod(m, caddr_t) + sizeof(struct in_addr), 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(" %x", ntohl(q->s_addr)); #endif *q++ = *p--; } /* * Last hop goes to final destination. */ *q = ip_srcrt.dst; #ifdef DIAGNOSTIC if (ipprintfs) printf(" %x\n", 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) struct mbuf *m; struct mbuf *mopt; { int i; struct ip *ip = mtod(m, struct ip *); caddr_t opts; int olen; olen = (ip->ip_hl<<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_hl = sizeof(struct ip) >> 2; } int inetctlerrmap[PRC_NCMDS] = { 0, 0, 0, 0, 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, EMSGSIZE, EHOSTUNREACH, 0, 0, 0, 0, 0, 0, ENOPROTOOPT }; /* * 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. */ void ip_forward(m, srcrt) struct mbuf *m; int srcrt; { 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 ifnet *destifp; #ifdef IPSEC struct ifnet dummyifp; #endif dest = 0; #ifdef DIAGNOSTIC if (ipprintfs) printf("forward: src %x dst %x ttl %x\n", ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl); #endif if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) { ipstat.ips_cantforward++; m_freem(m); return; } if (ip->ip_ttl <= IPTTLDEC) { icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0); return; } sin = satosin(&ipforward_rt.ro_dst); if ((rt = ipforward_rt.ro_rt) == 0 || ip->ip_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 = ip->ip_dst; rtalloc(&ipforward_rt); if (ipforward_rt.ro_rt == 0) { icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0); return; } rt = ipforward_rt.ro_rt; } /* * Save at most 68 bytes of the packet in case * we need to generate an ICMP message to the src. * Pullup to avoid sharing mbuf cluster between m and mcopy. */ mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT); if (mcopy) mcopy = m_pullup(mcopy, ip->ip_hl << 2); ip->ip_ttl -= IPTTLDEC; /* * 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. * Don't send redirect if we advertise destination's arp address * as ours (proxy arp). */ 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 && !ip_weadvertise(satosin(rt_key(rt))->sin_addr.s_addr)) { if (rt->rt_ifa && (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) == ifatoia(rt->rt_ifa)->ia_subnet) { if (rt->rt_flags & RTF_GATEWAY) dest = satosin(rt->rt_gateway)->sin_addr.s_addr; else dest = ip->ip_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 %x\n", code, (u_int32_t)dest); #endif } } error = ip_output(m, (struct mbuf *)0, &ipforward_rt, (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0, (void *)NULL, (void *)NULL); if (error) ipstat.ips_cantforward++; else { ipstat.ips_forward++; if (type) ipstat.ips_redirectsent++; else { if (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 (ipforward_rt.ro_rt) { struct rtentry *rt = ipforward_rt.ro_rt; destifp = ipforward_rt.ro_rt->rt_ifp; /* * XXX BUG ALERT * The "dummyifp" code relies upon the fact * that icmp_error() touches only ifp->if_mtu. */ if (rt->rt_rmx.rmx_mtu) { dummyifp.if_mtu = rt->rt_rmx.rmx_mtu; destifp = &dummyifp; } } #endif /*IPSEC*/ ipstat.ips_cantfrag++; break; case ENOBUFS: #if 1 /* * 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 the underlying interface is rate-limited. */ if (mcopy) m_freem(mcopy); return; #else type = ICMP_SOURCEQUENCH; code = 0; break; #endif } icmp_error(mcopy, type, code, dest, destifp); } int ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen) int *name; u_int namelen; void *oldp; size_t *oldlenp; void *newp; size_t newlen; { int error; /* Almost all sysctl names at this level are terminal. */ if (namelen != 1 && name[0] != IPCTL_IFQUEUE) return (ENOTDIR); switch (name[0]) { #ifdef notyet case IPCTL_DEFMTU: return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu)); #endif case IPCTL_SOURCEROUTE: /* * Don't allow this to change in a secure environment. */ if (newp && securelevel > 0) return (EPERM); return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_dosourceroute)); case IPCTL_MTUDISC: error = sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtudisc); if (ip_mtudisc != 0 && ip_mtudisc_timeout_q == NULL) { ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout); } else if (ip_mtudisc == 0 && ip_mtudisc_timeout_q != NULL) { rt_timer_queue_destroy(ip_mtudisc_timeout_q, TRUE); Free(ip_mtudisc_timeout_q); ip_mtudisc_timeout_q = NULL; } return error; case IPCTL_MTUDISCTIMEOUT: error = sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtudisc_timeout); if (ip_mtudisc_timeout_q != NULL) rt_timer_queue_change(ip_mtudisc_timeout_q, ip_mtudisc_timeout); return (error); case IPCTL_IPSEC_ENC_ALGORITHM: return (sysctl_tstring(oldp, oldlenp, newp, newlen, ipsec_def_enc, sizeof(ipsec_def_enc))); case IPCTL_IPSEC_AUTH_ALGORITHM: return (sysctl_tstring(oldp, oldlenp, newp, newlen, ipsec_def_auth, sizeof(ipsec_def_auth))); case IPCTL_IPSEC_IPCOMP_ALGORITHM: return (sysctl_tstring(oldp, oldlenp, newp, newlen, ipsec_def_comp, sizeof(ipsec_def_comp))); case IPCTL_IFQUEUE: return (sysctl_ifq(name + 1, namelen - 1, oldp, oldlenp, newp, newlen, &ipintrq)); default: if (name[0] < IPCTL_MAXID) return (sysctl_int_arr(ipctl_vars, name, namelen, oldp, oldlenp, newp, newlen)); return (EOPNOTSUPP); } /* NOTREACHED */ }