/* * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)ip_input.c 8.2 (Berkeley) 1/4/94 * $FreeBSD: src/sys/netinet/ip_input.c,v 1.271 2004/05/06 18:46:02 andre Exp $ */ #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_mac.h" #include "opt_pfil_hooks.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 #include #include #ifdef IPSEC #include #include #endif #ifdef FAST_IPSEC #include #include #endif int rsvp_on = 0; 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_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 = 1; 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 #ifdef PFIL_HOOKS struct pfil_head inet_pfil_hook; #endif static struct ifqueue ipintrq; static int ipqmaxlen = IFQ_MAXLEN; extern struct domain inetdomain; extern struct protosw 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 TAILQ_HEAD(ipqhead, ipq) ipq[IPREASS_NHASH]; struct mtx ipqlock; #define IPQ_LOCK() mtx_lock(&ipqlock) #define IPQ_UNLOCK() mtx_unlock(&ipqlock) #define IPQ_LOCK_INIT() mtx_init(&ipqlock, "ipqlock", NULL, MTX_DEF) #define IPQ_LOCK_ASSERT() mtx_assert(&ipqlock, MA_OWNED) #ifdef IPCTL_DEFMTU SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW, &ip_mtu, 0, "Default MTU"); #endif #ifdef IPSTEALTH int ipstealth = 0; SYSCTL_INT(_net_inet_ip, OID_AUTO, stealth, CTLFLAG_RW, &ipstealth, 0, ""); #endif static void ip_freef(struct ipqhead *, struct ipq *); /* * 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 protosw *pr; register int i; TAILQ_INIT(&in_ifaddrhead); in_ifaddrhashtbl = hashinit(INADDR_NHASH, M_IFADDR, &in_ifaddrhmask); 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; #ifdef PFIL_HOOKS inet_pfil_hook.ph_type = PFIL_TYPE_AF; inet_pfil_hook.ph_af = AF_INET; if ((i = pfil_head_register(&inet_pfil_hook)) != 0) printf("%s: WARNING: unable to register pfil hook, " "error %d\n", __func__, i); #endif /* PFIL_HOOKS */ IPQ_LOCK_INIT(); for (i = 0; i < IPREASS_NHASH; i++) TAILQ_INIT(&ipq[i]); maxnipq = nmbclusters / 32; maxfragsperpacket = 16; #ifndef RANDOM_IP_ID ip_id = time_second & 0xffff; #endif ipintrq.ifq_maxlen = ipqmaxlen; mtx_init(&ipintrq.ifq_mtx, "ip_inq", NULL, MTX_DEF); netisr_register(NETISR_IP, ip_input, &ipintrq, NETISR_MPSAFE); } /* * 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 = NULL; struct in_ifaddr *ia = NULL; struct ifaddr *ifa; int checkif, hlen = 0; u_short sum; struct in_addr pkt_dst; int dchg = 0; /* dest changed after fw */ #ifdef PFIL_HOOKS struct in_addr odst; /* original dst address */ #endif #ifdef FAST_IPSEC struct m_tag *mtag; struct tdb_ident *tdbi; struct secpolicy *sp; int s, error; #endif /* FAST_IPSEC */ M_ASSERTPKTHDR(m); if (m->m_flags & M_FASTFWD_OURS) { /* ip_fastforward firewall changed dest to local */ m->m_flags &= ~M_FASTFWD_OURS; /* for reflected mbufs */ goto ours; } 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->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)) == 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_getnhist(m)) goto pass; #endif #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF) /* * Bypass packet filtering for packets from a tunnel (gif). */ if (m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL) != NULL) goto pass; #endif #ifdef PFIL_HOOKS /* * Run through list of hooks for input packets. * * NB: Beware of the destination address changing (e.g. * by NAT rewriting). When this happens, tell * ip_forward to do the right thing. */ odst = ip->ip_dst; if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif, PFIL_IN) != 0) return; if (m == NULL) /* consumed by filter */ return; ip = mtod(m, struct ip *); dchg = (odst.s_addr != ip->ip_dst.s_addr); #endif /* PFIL_HOOKS */ #if defined(FAST_IPSEC) && !defined(IPSEC_FILTERGIF) pass: #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). */ if (hlen > sizeof (struct ip) && ip_dooptions(m, 0, NULL)) 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 = 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) && (dchg == 0); /* * 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, dchg, NULL); } 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; } /* * Attempt reassembly; if it succeeds, proceed. * ip_reass() will return a different mbuf. */ if (ip->ip_off & (IP_MF | IP_OFFMASK)) { m = ip_reass(m); if (m == NULL) return; ip = mtod(m, struct ip *); /* Get the header length of the reassembled packet */ hlen = ip->ip_hl << 2; } else ip->ip_len -= hlen; #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 0 if (args.next_hop && ip->ip_p == IPPROTO_TCP) { /* attach next hop info for TCP */ struct m_tag *mtag = m_tag_get(PACKET_TAG_IPFORWARD, sizeof(struct sockaddr_in *), M_NOWAIT); if (mtag == NULL) goto bad; *(struct sockaddr_in **)(mtag+1) = args.next_hop; m_tag_prepend(m, mtag); } #endif (*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen); return; bad: m_freem(m); } /* * Take incoming datagram fragment and try to reassemble it into * whole datagram. If the argument is the first fragment or one * in between the function will return NULL and store the mbuf * in the fragment chain. If the argument is the last fragment * the packet will be reassembled and the pointer to the new * mbuf returned for further processing. Only m_tags attached * to the first packet/fragment are preserved. * The IP header is adjusted out of iplen. */ struct mbuf * ip_reass(struct mbuf *m) { struct ip *ip; struct mbuf *p, *q, *nq, *t; struct ipq *fp = NULL; struct ipqhead *head; int i, hlen, next; u_int8_t ecn, ecn0; u_short hash; /* If maxnipq is 0, never accept fragments. */ if (maxnipq == 0) { ipstat.ips_fragments++; ipstat.ips_fragdropped++; goto dropfrag; } ip = mtod(m, struct ip *); hlen = ip->ip_hl << 2; hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id); head = &ipq[hash]; IPQ_LOCK(); /* * Look for queue of fragments * of this datagram. */ TAILQ_FOREACH(fp, head, ipq_list) 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 && #ifdef MAC mac_fragment_match(m, fp) && #endif ip->ip_p == fp->ipq_p) goto found; fp = NULL; /* * 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 */ struct ipq *q = TAILQ_LAST(head, ipqhead); if (q == NULL) { /* gak */ for (i = 0; i < IPREASS_NHASH; i++) { struct ipq *r = TAILQ_LAST(&ipq[i], ipqhead); if (r) { ipstat.ips_fragtimeout += r->ipq_nfrags; ip_freef(&ipq[i], r); break; } } } else { ipstat.ips_fragtimeout += q->ipq_nfrags; ip_freef(head, q); } } 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) { IPQ_UNLOCK(); ipstat.ips_toosmall++; /* XXX */ goto dropfrag; } 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. */ ipstat.ips_fragments++; m->m_pkthdr.header = ip; /* OLD CODE */ /* * 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 == NULL) { if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL) goto dropfrag; fp = mtod(t, struct ipq *); #ifdef MAC if (mac_init_ipq(fp, M_NOWAIT) != 0) { m_free(t); goto dropfrag; } mac_create_ipq(m, fp); #endif TAILQ_INSERT_HEAD(head, fp, ipq_list); 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; goto inserted; } else { fp->ipq_nfrags++; #ifdef MAC mac_update_ipq(m, fp); #endif } #define GETIP(m) ((struct ip*)((m)->m_pkthdr.header)) /* * 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 = ip->ip_tos & IPTOS_ECN_MASK; ecn0 = GETIP(fp->ipq_frags)->ip_tos & IPTOS_ECN_MASK; if (ecn == IPTOS_ECN_CE) { if (ecn0 == IPTOS_ECN_NOTECT) goto dropfrag; if (ecn0 != IPTOS_ECN_CE) GETIP(fp->ipq_frags)->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_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: /* * 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(head, fp); } goto done; } 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(head, fp); } goto done; } /* * Reassembly is complete. Make sure the packet is a sane size. */ q = fp->ipq_frags; ip = GETIP(q); if (next + (ip->ip_hl << 2) > IP_MAXPACKET) { ipstat.ips_toolong++; ipstat.ips_fragdropped += fp->ipq_nfrags; ip_freef(head, fp); goto done; } /* * 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 MAC mac_create_datagram_from_ipq(fp, m); mac_destroy_ipq(fp); #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; TAILQ_REMOVE(head, fp, ipq_list); nipq--; (void) m_free(dtom(fp)); 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 */ m_fixhdr(m); ipstat.ips_reassembled++; IPQ_UNLOCK(); return (m); dropfrag: ipstat.ips_fragdropped++; if (fp != NULL) fp->ipq_nfrags--; m_freem(m); done: IPQ_UNLOCK(); return (NULL); #undef GETIP } /* * Free a fragment reassembly header and all * associated datagrams. */ static void ip_freef(fhp, fp) struct ipqhead *fhp; struct ipq *fp; { register struct mbuf *q; IPQ_LOCK_ASSERT(); while (fp->ipq_frags) { q = fp->ipq_frags; fp->ipq_frags = q->m_nextpkt; m_freem(q); } TAILQ_REMOVE(fhp, fp, ipq_list); (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; IPQ_LOCK(); for (i = 0; i < IPREASS_NHASH; i++) { for(fp = TAILQ_FIRST(&ipq[i]); fp;) { struct ipq *fpp; fpp = fp; fp = TAILQ_NEXT(fp, ipq_list); if(--fpp->ipq_ttl == 0) { ipstat.ips_fragtimeout += fpp->ipq_nfrags; ip_freef(&ipq[i], fpp); } } } /* * 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 && !TAILQ_EMPTY(&ipq[i])) { ipstat.ips_fragdropped += TAILQ_FIRST(&ipq[i])->ipq_nfrags; ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i])); } } } IPQ_UNLOCK(); splx(s); } /* * Drain off all datagram fragments. */ void ip_drain() { int i; IPQ_LOCK(); for (i = 0; i < IPREASS_NHASH; i++) { while(!TAILQ_EMPTY(&ipq[i])) { ipstat.ips_fragdropped += TAILQ_FIRST(&ipq[i])->ipq_nfrags; ip_freef(&ipq[i], TAILQ_FIRST(&ipq[i])); } } IPQ_UNLOCK(); in_rtqdrain(); } /* * 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 route sro; struct sockaddr_in *sin; struct in_ifaddr *ifa; bzero(&sro, sizeof(sro)); sin = (struct sockaddr_in *)&sro.ro_dst; sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = dst; rtalloc_ign(&sro, RTF_CLONING); if (sro.ro_rt == NULL) return ((struct in_ifaddr *)0); ifa = ifatoia(sro.ro_rt->rt_ifa); RTFREE(sro.ro_rt); return ifa; } u_char inetctlerrmap[PRC_NCMDS] = { 0, 0, 0, 0, 0, EMSGSIZE, EHOSTDOWN, EHOSTUNREACH, EHOSTUNREACH, EHOSTUNREACH, ECONNREFUSED, ECONNREFUSED, EMSGSIZE, EHOSTUNREACH, 0, 0, 0, 0, EHOSTUNREACH, 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. */ void ip_forward(struct mbuf *m, int srcrt, struct sockaddr_in *next_hop) { struct ip *ip = mtod(m, struct ip *); struct in_ifaddr *ia; 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 /* * 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, 0, 0); return; } #ifdef IPSTEALTH } #endif if ((ia = ip_rtaddr(pkt_dst)) == 0) { icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0); return; } /* * 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->ip_hl << 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. */ dest = 0; if (ipsendredirects && ia->ia_ifp == m->m_pkthdr.rcvif) { struct sockaddr_in *sin; struct route ro; struct rtentry *rt; bzero(&ro, sizeof(ro)); sin = (struct sockaddr_in *)&ro.ro_dst; sin->sin_family = AF_INET; sin->sin_len = sizeof(*sin); sin->sin_addr = pkt_dst; rtalloc_ign(&ro, RTF_CLONING); rt = ro.ro_rt; if (rt && (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 } } if (rt) RTFREE(rt); } if (next_hop) { struct m_tag *mtag = m_tag_get(PACKET_TAG_IPFORWARD, sizeof(struct sockaddr_in *), M_NOWAIT); if (mtag == NULL) { m_freem(m); return; } *(struct sockaddr_in **)(mtag+1) = next_hop; m_tag_prepend(m, mtag); } error = ip_output(m, (struct mbuf *)0, NULL, IP_FORWARDING, 0, 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; #if defined(IPSEC) || defined(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!!! */ { struct secpolicy *sp = NULL; int ipsecerror; int ipsechdr; struct route *ro; #ifdef IPSEC sp = ipsec4_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, IP_FORWARDING, &ipsecerror); #else /* FAST_IPSEC */ sp = ipsec_getpolicybyaddr(mcopy, IPSEC_DIR_OUTBOUND, IP_FORWARDING, &ipsecerror); #endif if (sp != NULL) { /* 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; } } #ifdef IPSEC key_freesp(sp); #else /* FAST_IPSEC */ KEY_FREESP(&sp); #endif ipstat.ips_cantfrag++; break; } else #endif /*IPSEC || FAST_IPSEC*/ destifp = ia->ia_ifp; #if defined(IPSEC) || defined(FAST_IPSEC) } #endif /*IPSEC || FAST_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_BINTIME | SO_TIMESTAMP)) { struct bintime bt; bintime(&bt); if (inp->inp_socket->so_options & SO_BINTIME) { *mp = sbcreatecontrol((caddr_t) &bt, sizeof(bt), SCM_BINTIME, SOL_SOCKET); if (*mp) mp = &(*mp)->m_next; } if (inp->inp_socket->so_options & SO_TIMESTAMP) { struct timeval tv; bintime2timeval(&bt, &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; } if (inp->inp_flags & INP_RECVTTL) { *mp = sbcreatecontrol((caddr_t) &ip->ip_ttl, sizeof(u_char), IP_RECVTTL, 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 *) (ifaddr_byindex(ifp->if_index)->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 need to be locked when we remove Giant. * * They could also be moved to ip_mroute.c, since all the RSVP * handling is done there already. */ static int ip_rsvp_on; struct socket *ip_rsvpd; 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) /* XXX must fixup manually */ { if (rsvp_input_p) { /* call the real one if loaded */ rsvp_input_p(m, off); 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); return; } /* Drop the packet */ m_freem(m); }