/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2015-2019 Yandex LLC * Copyright (c) 2015-2019 Andrey V. Elsukov * * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ #include __FBSDID("$FreeBSD$"); #include "opt_ipstealth.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 #include #include #include #include #include #include "ip_fw_nat64.h" #include "nat64_translate.h" typedef int (*nat64_output_t)(struct ifnet *, struct mbuf *, struct sockaddr *, struct nat64_counters *, void *); typedef int (*nat64_output_one_t)(struct mbuf *, struct nat64_counters *, void *); static struct nhop_object *nat64_find_route4(struct sockaddr_in *, struct mbuf *); static struct nhop_object *nat64_find_route6(struct sockaddr_in6 *, struct mbuf *); static int nat64_output_one(struct mbuf *, struct nat64_counters *, void *); static int nat64_output(struct ifnet *, struct mbuf *, struct sockaddr *, struct nat64_counters *, void *); static int nat64_direct_output_one(struct mbuf *, struct nat64_counters *, void *); static int nat64_direct_output(struct ifnet *, struct mbuf *, struct sockaddr *, struct nat64_counters *, void *); struct nat64_methods { nat64_output_t output; nat64_output_one_t output_one; }; static const struct nat64_methods nat64_netisr = { .output = nat64_output, .output_one = nat64_output_one }; static const struct nat64_methods nat64_direct = { .output = nat64_direct_output, .output_one = nat64_direct_output_one }; /* These variables should be initialized explicitly on module loading */ VNET_DEFINE_STATIC(const struct nat64_methods *, nat64out); VNET_DEFINE_STATIC(const int *, nat64ipstealth); VNET_DEFINE_STATIC(const int *, nat64ip6stealth); #define V_nat64out VNET(nat64out) #define V_nat64ipstealth VNET(nat64ipstealth) #define V_nat64ip6stealth VNET(nat64ip6stealth) static const int stealth_on = 1; #ifndef IPSTEALTH static const int stealth_off = 0; #endif void nat64_set_output_method(int direct) { if (direct != 0) { V_nat64out = &nat64_direct; #ifdef IPSTEALTH /* Honor corresponding variables, if IPSTEALTH is defined */ V_nat64ipstealth = &V_ipstealth; V_nat64ip6stealth = &V_ip6stealth; #else /* otherwise we need to decrement HLIM/TTL for direct case */ V_nat64ipstealth = V_nat64ip6stealth = &stealth_off; #endif } else { V_nat64out = &nat64_netisr; /* Leave TTL/HLIM decrementing to forwarding code */ V_nat64ipstealth = V_nat64ip6stealth = &stealth_on; } } int nat64_get_output_method(void) { return (V_nat64out == &nat64_direct ? 1: 0); } static void nat64_log(struct pfloghdr *logdata, struct mbuf *m, sa_family_t family) { logdata->dir = PF_OUT; logdata->af = family; ipfw_bpf_mtap2(logdata, PFLOG_HDRLEN, m); } static int nat64_direct_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, struct nat64_counters *stats, void *logdata) { int error; if (logdata != NULL) nat64_log(logdata, m, dst->sa_family); error = (*ifp->if_output)(ifp, m, dst, NULL); if (error != 0) NAT64STAT_INC(stats, oerrors); return (error); } static int nat64_direct_output_one(struct mbuf *m, struct nat64_counters *stats, void *logdata) { struct nhop_object *nh4 = NULL; struct nhop_object *nh6 = NULL; struct sockaddr_in6 dst6; struct sockaddr_in dst4; struct sockaddr *dst; struct ip6_hdr *ip6; struct ip *ip4; struct ifnet *ifp; int error; ip4 = mtod(m, struct ip *); error = 0; switch (ip4->ip_v) { case IPVERSION: dst4.sin_addr = ip4->ip_dst; nh4 = nat64_find_route4(&dst4, m); if (nh4 == NULL) { NAT64STAT_INC(stats, noroute4); error = EHOSTUNREACH; } else { ifp = nh4->nh_ifp; dst = (struct sockaddr *)&dst4; } break; case (IPV6_VERSION >> 4): ip6 = mtod(m, struct ip6_hdr *); dst6.sin6_addr = ip6->ip6_dst; nh6 = nat64_find_route6(&dst6, m); if (nh6 == NULL) { NAT64STAT_INC(stats, noroute6); error = EHOSTUNREACH; } else { ifp = nh6->nh_ifp; dst = (struct sockaddr *)&dst6; } break; default: m_freem(m); NAT64STAT_INC(stats, dropped); DPRINTF(DP_DROPS, "dropped due to unknown IP version"); return (EAFNOSUPPORT); } if (error != 0) { m_freem(m); return (EHOSTUNREACH); } if (logdata != NULL) nat64_log(logdata, m, dst->sa_family); error = (*ifp->if_output)(ifp, m, dst, NULL); if (error != 0) NAT64STAT_INC(stats, oerrors); return (error); } static int nat64_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst, struct nat64_counters *stats, void *logdata) { struct ip *ip4; int ret, af; ip4 = mtod(m, struct ip *); switch (ip4->ip_v) { case IPVERSION: af = AF_INET; ret = NETISR_IP; break; case (IPV6_VERSION >> 4): af = AF_INET6; ret = NETISR_IPV6; break; default: m_freem(m); NAT64STAT_INC(stats, dropped); DPRINTF(DP_DROPS, "unknown IP version"); return (EAFNOSUPPORT); } if (logdata != NULL) nat64_log(logdata, m, af); if (m->m_pkthdr.rcvif == NULL) m->m_pkthdr.rcvif = V_loif; ret = netisr_queue(ret, m); if (ret != 0) NAT64STAT_INC(stats, oerrors); return (ret); } static int nat64_output_one(struct mbuf *m, struct nat64_counters *stats, void *logdata) { return (nat64_output(NULL, m, NULL, stats, logdata)); } /* * Check the given IPv6 prefix and length according to RFC6052: * The prefixes can only have one of the following lengths: * 32, 40, 48, 56, 64, or 96 (The Well-Known Prefix is 96 bits long). * Returns zero on success, otherwise EINVAL. */ int nat64_check_prefixlen(int length) { switch (length) { case 32: case 40: case 48: case 56: case 64: case 96: return (0); } return (EINVAL); } int nat64_check_prefix6(const struct in6_addr *prefix, int length) { if (nat64_check_prefixlen(length) != 0) return (EINVAL); /* Well-known prefix has 96 prefix length */ if (IN6_IS_ADDR_WKPFX(prefix) && length != 96) return (EINVAL); /* Bits 64 to 71 must be set to zero */ if (prefix->__u6_addr.__u6_addr8[8] != 0) return (EINVAL); /* Some extra checks */ if (IN6_IS_ADDR_MULTICAST(prefix) || IN6_IS_ADDR_UNSPECIFIED(prefix) || IN6_IS_ADDR_LOOPBACK(prefix)) return (EINVAL); return (0); } int nat64_check_private_ip4(const struct nat64_config *cfg, in_addr_t ia) { if (cfg->flags & NAT64_ALLOW_PRIVATE) return (0); /* WKPFX must not be used to represent non-global IPv4 addresses */ if (cfg->flags & NAT64_WKPFX) { /* IN_PRIVATE */ if ((ia & htonl(0xff000000)) == htonl(0x0a000000) || (ia & htonl(0xfff00000)) == htonl(0xac100000) || (ia & htonl(0xffff0000)) == htonl(0xc0a80000)) return (1); /* * RFC 5735: * 192.0.0.0/24 - reserved for IETF protocol assignments * 192.88.99.0/24 - for use as 6to4 relay anycast addresses * 198.18.0.0/15 - for use in benchmark tests * 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24 - for use * in documentation and example code */ if ((ia & htonl(0xffffff00)) == htonl(0xc0000000) || (ia & htonl(0xffffff00)) == htonl(0xc0586300) || (ia & htonl(0xfffffe00)) == htonl(0xc6120000) || (ia & htonl(0xffffff00)) == htonl(0xc0000200) || (ia & htonl(0xfffffe00)) == htonl(0xc6336400) || (ia & htonl(0xffffff00)) == htonl(0xcb007100)) return (1); } return (0); } /* * Embed @ia IPv4 address into @ip6 IPv6 address. * Place to embedding determined from prefix length @plen. */ void nat64_embed_ip4(struct in6_addr *ip6, int plen, in_addr_t ia) { switch (plen) { case 32: case 96: ip6->s6_addr32[plen / 32] = ia; break; case 40: case 48: case 56: /* * Preserve prefix bits. * Since suffix bits should be zero and reserved for future * use, we just overwrite the whole word, where they are. */ ip6->s6_addr32[1] &= 0xffffffff << (32 - plen % 32); #if BYTE_ORDER == BIG_ENDIAN ip6->s6_addr32[1] |= ia >> (plen % 32); ip6->s6_addr32[2] = ia << (24 - plen % 32); #elif BYTE_ORDER == LITTLE_ENDIAN ip6->s6_addr32[1] |= ia << (plen % 32); ip6->s6_addr32[2] = ia >> (24 - plen % 32); #endif break; case 64: #if BYTE_ORDER == BIG_ENDIAN ip6->s6_addr32[2] = ia >> 8; ip6->s6_addr32[3] = ia << 24; #elif BYTE_ORDER == LITTLE_ENDIAN ip6->s6_addr32[2] = ia << 8; ip6->s6_addr32[3] = ia >> 24; #endif break; default: panic("Wrong plen: %d", plen); }; /* * Bits 64 to 71 of the address are reserved for compatibility * with the host identifier format defined in the IPv6 addressing * architecture [RFC4291]. These bits MUST be set to zero. */ ip6->s6_addr8[8] = 0; } in_addr_t nat64_extract_ip4(const struct in6_addr *ip6, int plen) { in_addr_t ia; /* * According to RFC 6052 p2.2: * IPv4-embedded IPv6 addresses are composed of a variable-length * prefix, the embedded IPv4 address, and a variable length suffix. * The suffix bits are reserved for future extensions and SHOULD * be set to zero. */ switch (plen) { case 32: if (ip6->s6_addr32[3] != 0 || ip6->s6_addr32[2] != 0) goto badip6; break; case 40: if (ip6->s6_addr32[3] != 0 || (ip6->s6_addr32[2] & htonl(0xff00ffff)) != 0) goto badip6; break; case 48: if (ip6->s6_addr32[3] != 0 || (ip6->s6_addr32[2] & htonl(0xff0000ff)) != 0) goto badip6; break; case 56: if (ip6->s6_addr32[3] != 0 || ip6->s6_addr8[8] != 0) goto badip6; break; case 64: if (ip6->s6_addr8[8] != 0 || (ip6->s6_addr32[3] & htonl(0x00ffffff)) != 0) goto badip6; }; switch (plen) { case 32: case 96: ia = ip6->s6_addr32[plen / 32]; break; case 40: case 48: case 56: #if BYTE_ORDER == BIG_ENDIAN ia = (ip6->s6_addr32[1] << (plen % 32)) | (ip6->s6_addr32[2] >> (24 - plen % 32)); #elif BYTE_ORDER == LITTLE_ENDIAN ia = (ip6->s6_addr32[1] >> (plen % 32)) | (ip6->s6_addr32[2] << (24 - plen % 32)); #endif break; case 64: #if BYTE_ORDER == BIG_ENDIAN ia = (ip6->s6_addr32[2] << 8) | (ip6->s6_addr32[3] >> 24); #elif BYTE_ORDER == LITTLE_ENDIAN ia = (ip6->s6_addr32[2] >> 8) | (ip6->s6_addr32[3] << 24); #endif break; default: return (0); }; if (nat64_check_ip4(ia) == 0) return (ia); DPRINTF(DP_GENERIC | DP_DROPS, "invalid destination address: %08x", ia); return (0); badip6: DPRINTF(DP_GENERIC | DP_DROPS, "invalid IPv4-embedded IPv6 address"); return (0); } /* * According to RFC 1624 the equation for incremental checksum update is: * HC' = ~(~HC + ~m + m') -- [Eqn. 3] * HC' = HC - ~m - m' -- [Eqn. 4] * So, when we are replacing IPv4 addresses to IPv6, we * can assume, that new bytes previously were zeros, and vise versa - * when we replacing IPv6 addresses to IPv4, now unused bytes become * zeros. The payload length in pseudo header has bigger size, but one * half of it should be zero. Using the equation 4 we get: * HC' = HC - (~m0 + m0') -- m0 is first changed word * HC' = (HC - (~m0 + m0')) - (~m1 + m1') -- m1 is second changed word * HC' = HC - ~m0 - m0' - ~m1 - m1' - ... = * = HC - sum(~m[i] + m'[i]) * * The function result should be used as follows: * IPv6 to IPv4: HC' = cksum_add(HC, result) * IPv4 to IPv6: HC' = cksum_add(HC, ~result) */ static uint16_t nat64_cksum_convert(struct ip6_hdr *ip6, struct ip *ip) { uint32_t sum; uint16_t *p; sum = ~ip->ip_src.s_addr >> 16; sum += ~ip->ip_src.s_addr & 0xffff; sum += ~ip->ip_dst.s_addr >> 16; sum += ~ip->ip_dst.s_addr & 0xffff; for (p = (uint16_t *)&ip6->ip6_src; p < (uint16_t *)(&ip6->ip6_src + 2); p++) sum += *p; while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16); return (sum); } static void nat64_init_ip4hdr(const struct ip6_hdr *ip6, const struct ip6_frag *frag, uint16_t plen, uint8_t proto, struct ip *ip) { /* assume addresses are already initialized */ ip->ip_v = IPVERSION; ip->ip_hl = sizeof(*ip) >> 2; ip->ip_tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; ip->ip_len = htons(sizeof(*ip) + plen); ip->ip_ttl = ip6->ip6_hlim; if (*V_nat64ip6stealth == 0) ip->ip_ttl -= IPV6_HLIMDEC; ip->ip_sum = 0; ip->ip_p = (proto == IPPROTO_ICMPV6) ? IPPROTO_ICMP: proto; ip_fillid(ip); if (frag != NULL) { ip->ip_off = htons(ntohs(frag->ip6f_offlg) >> 3); if (frag->ip6f_offlg & IP6F_MORE_FRAG) ip->ip_off |= htons(IP_MF); } else { ip->ip_off = htons(IP_DF); } ip->ip_sum = in_cksum_hdr(ip); } #define FRAGSZ(mtu) ((mtu) - sizeof(struct ip6_hdr) - sizeof(struct ip6_frag)) static NAT64NOINLINE int nat64_fragment6(struct nat64_counters *stats, struct ip6_hdr *ip6, struct mbufq *mq, struct mbuf *m, uint32_t mtu, uint16_t ip_id, uint16_t ip_off) { struct ip6_frag ip6f; struct mbuf *n; uint16_t hlen, len, offset; int plen; plen = ntohs(ip6->ip6_plen); hlen = sizeof(struct ip6_hdr); /* Fragmentation isn't needed */ if (ip_off == 0 && plen <= mtu - hlen) { M_PREPEND(m, hlen, M_NOWAIT); if (m == NULL) { NAT64STAT_INC(stats, nomem); return (ENOMEM); } bcopy(ip6, mtod(m, void *), hlen); if (mbufq_enqueue(mq, m) != 0) { m_freem(m); NAT64STAT_INC(stats, dropped); DPRINTF(DP_DROPS, "dropped due to mbufq overflow"); return (ENOBUFS); } return (0); } hlen += sizeof(struct ip6_frag); ip6f.ip6f_reserved = 0; ip6f.ip6f_nxt = ip6->ip6_nxt; ip6->ip6_nxt = IPPROTO_FRAGMENT; if (ip_off != 0) { /* * We have got an IPv4 fragment. * Use offset value and ip_id from original fragment. */ ip6f.ip6f_ident = htonl(ntohs(ip_id)); offset = (ntohs(ip_off) & IP_OFFMASK) << 3; NAT64STAT_INC(stats, ifrags); } else { /* The packet size exceeds interface MTU */ ip6f.ip6f_ident = htonl(ip6_randomid()); offset = 0; /* First fragment*/ } while (plen > 0 && m != NULL) { n = NULL; len = FRAGSZ(mtu) & ~7; if (len > plen) len = plen; ip6->ip6_plen = htons(len + sizeof(ip6f)); ip6f.ip6f_offlg = ntohs(offset); if (len < plen || (ip_off & htons(IP_MF)) != 0) ip6f.ip6f_offlg |= IP6F_MORE_FRAG; offset += len; plen -= len; if (plen > 0) { n = m_split(m, len, M_NOWAIT); if (n == NULL) goto fail; } M_PREPEND(m, hlen, M_NOWAIT); if (m == NULL) goto fail; bcopy(ip6, mtod(m, void *), sizeof(struct ip6_hdr)); bcopy(&ip6f, mtodo(m, sizeof(struct ip6_hdr)), sizeof(struct ip6_frag)); if (mbufq_enqueue(mq, m) != 0) goto fail; m = n; } NAT64STAT_ADD(stats, ofrags, mbufq_len(mq)); return (0); fail: if (m != NULL) m_freem(m); if (n != NULL) m_freem(n); mbufq_drain(mq); NAT64STAT_INC(stats, nomem); return (ENOMEM); } static struct nhop_object * nat64_find_route6(struct sockaddr_in6 *dst, struct mbuf *m) { struct nhop_object *nh; NET_EPOCH_ASSERT(); nh = fib6_lookup(M_GETFIB(m), &dst->sin6_addr, 0, NHR_NONE, 0); if (nh == NULL) return (NULL); if (nh->nh_flags & (NHF_BLACKHOLE | NHF_REJECT)) return (NULL); dst->sin6_family = AF_INET6; dst->sin6_len = sizeof(*dst); if (nh->nh_flags & NHF_GATEWAY) dst->sin6_addr = nh->gw6_sa.sin6_addr; dst->sin6_port = 0; dst->sin6_scope_id = 0; dst->sin6_flowinfo = 0; return (nh); } #define NAT64_ICMP6_PLEN 64 static NAT64NOINLINE void nat64_icmp6_reflect(struct mbuf *m, uint8_t type, uint8_t code, uint32_t mtu, struct nat64_counters *stats, void *logdata) { struct icmp6_hdr *icmp6; struct ip6_hdr *ip6, *oip6; struct mbuf *n; int len, plen, proto; len = 0; proto = nat64_getlasthdr(m, &len); if (proto < 0) { DPRINTF(DP_DROPS, "mbuf isn't contigious"); goto freeit; } /* * Do not send ICMPv6 in reply to ICMPv6 errors. */ if (proto == IPPROTO_ICMPV6) { if (m->m_len < len + sizeof(*icmp6)) { DPRINTF(DP_DROPS, "mbuf isn't contigious"); goto freeit; } icmp6 = mtodo(m, len); if (icmp6->icmp6_type < ICMP6_ECHO_REQUEST || icmp6->icmp6_type == ND_REDIRECT) { DPRINTF(DP_DROPS, "do not send ICMPv6 in reply to " "ICMPv6 errors"); goto freeit; } /* * If there are extra headers between IPv6 and ICMPv6, * strip off them. */ if (len > sizeof(struct ip6_hdr)) { /* * NOTE: ipfw_chk already did m_pullup() and it is * expected that data is contigious from the start * of IPv6 header up to the end of ICMPv6 header. */ bcopy(mtod(m, caddr_t), mtodo(m, len - sizeof(struct ip6_hdr)), sizeof(struct ip6_hdr)); m_adj(m, len - sizeof(struct ip6_hdr)); } } /* if (icmp6_ratelimit(&ip6->ip6_src, type, code)) goto freeit; */ ip6 = mtod(m, struct ip6_hdr *); switch (type) { case ICMP6_DST_UNREACH: case ICMP6_PACKET_TOO_BIG: case ICMP6_TIME_EXCEEDED: case ICMP6_PARAM_PROB: break; default: goto freeit; } /* Calculate length of ICMPv6 payload */ len = (m->m_pkthdr.len > NAT64_ICMP6_PLEN) ? NAT64_ICMP6_PLEN: m->m_pkthdr.len; /* Create new ICMPv6 datagram */ plen = len + sizeof(struct icmp6_hdr); n = m_get2(sizeof(struct ip6_hdr) + plen + max_hdr, M_NOWAIT, MT_HEADER, M_PKTHDR); if (n == NULL) { NAT64STAT_INC(stats, nomem); m_freem(m); return; } /* * Move pkthdr from original mbuf. We should have initialized some * fields, because we can reinject this mbuf to netisr and it will * go through input path (it requires at least rcvif should be set). * Also do M_ALIGN() to reduce chances of need to allocate new mbuf * in the chain, when we will do M_PREPEND() or make some type of * tunneling. */ m_move_pkthdr(n, m); M_ALIGN(n, sizeof(struct ip6_hdr) + plen + max_hdr); n->m_len = n->m_pkthdr.len = sizeof(struct ip6_hdr) + plen; oip6 = mtod(n, struct ip6_hdr *); /* * Make IPv6 source address selection for reflected datagram. * nat64_check_ip6() doesn't allow scoped addresses, therefore * we use zero scopeid. */ if (in6_selectsrc_addr(M_GETFIB(n), &ip6->ip6_src, 0, n->m_pkthdr.rcvif, &oip6->ip6_src, NULL) != 0) { /* * Failed to find proper source address, drop the packet. */ m_freem(n); goto freeit; } oip6->ip6_dst = ip6->ip6_src; oip6->ip6_nxt = IPPROTO_ICMPV6; oip6->ip6_flow = 0; oip6->ip6_vfc |= IPV6_VERSION; oip6->ip6_hlim = V_ip6_defhlim; oip6->ip6_plen = htons(plen); icmp6 = mtodo(n, sizeof(struct ip6_hdr)); icmp6->icmp6_cksum = 0; icmp6->icmp6_type = type; icmp6->icmp6_code = code; icmp6->icmp6_mtu = htonl(mtu); m_copydata(m, 0, len, mtodo(n, sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr))); icmp6->icmp6_cksum = in6_cksum(n, IPPROTO_ICMPV6, sizeof(struct ip6_hdr), plen); m_freem(m); V_nat64out->output_one(n, stats, logdata); return; freeit: NAT64STAT_INC(stats, dropped); m_freem(m); } static struct nhop_object * nat64_find_route4(struct sockaddr_in *dst, struct mbuf *m) { struct nhop_object *nh; NET_EPOCH_ASSERT(); nh = fib4_lookup(M_GETFIB(m), dst->sin_addr, 0, NHR_NONE, 0); if (nh == NULL) return (NULL); if (nh->nh_flags & (NHF_BLACKHOLE | NHF_BROADCAST | NHF_REJECT)) return (NULL); dst->sin_family = AF_INET; dst->sin_len = sizeof(*dst); if (nh->nh_flags & NHF_GATEWAY) dst->sin_addr = nh->gw4_sa.sin_addr; dst->sin_port = 0; return (nh); } #define NAT64_ICMP_PLEN 64 static NAT64NOINLINE void nat64_icmp_reflect(struct mbuf *m, uint8_t type, uint8_t code, uint16_t mtu, struct nat64_counters *stats, void *logdata) { struct icmp *icmp; struct ip *ip, *oip; struct mbuf *n; int len, plen; ip = mtod(m, struct ip *); /* Do not send ICMP error if packet is not the first fragment */ if (ip->ip_off & ~ntohs(IP_MF|IP_DF)) { DPRINTF(DP_DROPS, "not first fragment"); goto freeit; } /* Do not send ICMP in reply to ICMP errors */ if (ip->ip_p == IPPROTO_ICMP) { if (m->m_len < (ip->ip_hl << 2)) { DPRINTF(DP_DROPS, "mbuf isn't contigious"); goto freeit; } icmp = mtodo(m, ip->ip_hl << 2); if (!ICMP_INFOTYPE(icmp->icmp_type)) { DPRINTF(DP_DROPS, "do not send ICMP in reply to " "ICMP errors"); goto freeit; } } switch (type) { case ICMP_UNREACH: case ICMP_TIMXCEED: case ICMP_PARAMPROB: break; default: goto freeit; } /* Calculate length of ICMP payload */ len = (m->m_pkthdr.len > NAT64_ICMP_PLEN) ? (ip->ip_hl << 2) + 8: m->m_pkthdr.len; /* Create new ICMPv4 datagram */ plen = len + sizeof(struct icmphdr) + sizeof(uint32_t); n = m_get2(sizeof(struct ip) + plen + max_hdr, M_NOWAIT, MT_HEADER, M_PKTHDR); if (n == NULL) { NAT64STAT_INC(stats, nomem); m_freem(m); return; } m_move_pkthdr(n, m); M_ALIGN(n, sizeof(struct ip) + plen + max_hdr); n->m_len = n->m_pkthdr.len = sizeof(struct ip) + plen; oip = mtod(n, struct ip *); oip->ip_v = IPVERSION; oip->ip_hl = sizeof(struct ip) >> 2; oip->ip_tos = 0; oip->ip_len = htons(n->m_pkthdr.len); oip->ip_ttl = V_ip_defttl; oip->ip_p = IPPROTO_ICMP; ip_fillid(oip); oip->ip_off = htons(IP_DF); oip->ip_src = ip->ip_dst; oip->ip_dst = ip->ip_src; oip->ip_sum = 0; oip->ip_sum = in_cksum_hdr(oip); icmp = mtodo(n, sizeof(struct ip)); icmp->icmp_type = type; icmp->icmp_code = code; icmp->icmp_cksum = 0; icmp->icmp_pmvoid = 0; icmp->icmp_nextmtu = htons(mtu); m_copydata(m, 0, len, mtodo(n, sizeof(struct ip) + sizeof(struct icmphdr) + sizeof(uint32_t))); icmp->icmp_cksum = in_cksum_skip(n, sizeof(struct ip) + plen, sizeof(struct ip)); m_freem(m); V_nat64out->output_one(n, stats, logdata); return; freeit: NAT64STAT_INC(stats, dropped); m_freem(m); } /* Translate ICMP echo request/reply into ICMPv6 */ static void nat64_icmp_handle_echo(struct ip6_hdr *ip6, struct icmp6_hdr *icmp6, uint16_t id, uint8_t type) { uint16_t old; old = *(uint16_t *)icmp6; /* save type+code in one word */ icmp6->icmp6_type = type; /* Reflect ICMPv6 -> ICMPv4 type translation in the cksum */ icmp6->icmp6_cksum = cksum_adjust(icmp6->icmp6_cksum, old, *(uint16_t *)icmp6); if (id != 0) { old = icmp6->icmp6_id; icmp6->icmp6_id = id; /* Reflect ICMP id translation in the cksum */ icmp6->icmp6_cksum = cksum_adjust(icmp6->icmp6_cksum, old, id); } /* Reflect IPv6 pseudo header in the cksum */ icmp6->icmp6_cksum = ~in6_cksum_pseudo(ip6, ntohs(ip6->ip6_plen), IPPROTO_ICMPV6, ~icmp6->icmp6_cksum); } static NAT64NOINLINE struct mbuf * nat64_icmp_translate(struct mbuf *m, struct ip6_hdr *ip6, uint16_t icmpid, int offset, struct nat64_config *cfg) { struct ip ip; struct icmp *icmp; struct tcphdr *tcp; struct udphdr *udp; struct ip6_hdr *eip6; struct mbuf *n; uint32_t mtu; int len, hlen, plen; uint8_t type, code; if (m->m_len < offset + ICMP_MINLEN) m = m_pullup(m, offset + ICMP_MINLEN); if (m == NULL) { NAT64STAT_INC(&cfg->stats, nomem); return (m); } mtu = 0; icmp = mtodo(m, offset); /* RFC 7915 p4.2 */ switch (icmp->icmp_type) { case ICMP_ECHOREPLY: type = ICMP6_ECHO_REPLY; code = 0; break; case ICMP_UNREACH: type = ICMP6_DST_UNREACH; switch (icmp->icmp_code) { case ICMP_UNREACH_NET: case ICMP_UNREACH_HOST: case ICMP_UNREACH_SRCFAIL: case ICMP_UNREACH_NET_UNKNOWN: case ICMP_UNREACH_HOST_UNKNOWN: case ICMP_UNREACH_TOSNET: case ICMP_UNREACH_TOSHOST: code = ICMP6_DST_UNREACH_NOROUTE; break; case ICMP_UNREACH_PROTOCOL: type = ICMP6_PARAM_PROB; code = ICMP6_PARAMPROB_NEXTHEADER; break; case ICMP_UNREACH_PORT: code = ICMP6_DST_UNREACH_NOPORT; break; case ICMP_UNREACH_NEEDFRAG: type = ICMP6_PACKET_TOO_BIG; code = 0; /* XXX: needs an additional look */ mtu = max(IPV6_MMTU, ntohs(icmp->icmp_nextmtu) + 20); break; case ICMP_UNREACH_NET_PROHIB: case ICMP_UNREACH_HOST_PROHIB: case ICMP_UNREACH_FILTER_PROHIB: case ICMP_UNREACH_PRECEDENCE_CUTOFF: code = ICMP6_DST_UNREACH_ADMIN; break; default: DPRINTF(DP_DROPS, "Unsupported ICMP type %d, code %d", icmp->icmp_type, icmp->icmp_code); goto freeit; } break; case ICMP_TIMXCEED: type = ICMP6_TIME_EXCEEDED; code = icmp->icmp_code; break; case ICMP_ECHO: type = ICMP6_ECHO_REQUEST; code = 0; break; case ICMP_PARAMPROB: type = ICMP6_PARAM_PROB; switch (icmp->icmp_code) { case ICMP_PARAMPROB_ERRATPTR: case ICMP_PARAMPROB_LENGTH: code = ICMP6_PARAMPROB_HEADER; switch (icmp->icmp_pptr) { case 0: /* Version/IHL */ case 1: /* Type Of Service */ mtu = icmp->icmp_pptr; break; case 2: /* Total Length */ case 3: mtu = 4; /* Payload Length */ break; case 8: /* Time to Live */ mtu = 7; /* Hop Limit */ break; case 9: /* Protocol */ mtu = 6; /* Next Header */ break; case 12: /* Source address */ case 13: case 14: case 15: mtu = 8; break; case 16: /* Destination address */ case 17: case 18: case 19: mtu = 24; break; default: /* Silently drop */ DPRINTF(DP_DROPS, "Unsupported ICMP type %d," " code %d, pptr %d", icmp->icmp_type, icmp->icmp_code, icmp->icmp_pptr); goto freeit; } break; default: DPRINTF(DP_DROPS, "Unsupported ICMP type %d," " code %d, pptr %d", icmp->icmp_type, icmp->icmp_code, icmp->icmp_pptr); goto freeit; } break; default: DPRINTF(DP_DROPS, "Unsupported ICMP type %d, code %d", icmp->icmp_type, icmp->icmp_code); goto freeit; } /* * For echo request/reply we can use original payload, * but we need adjust icmp_cksum, because ICMPv6 cksum covers * IPv6 pseudo header and ICMPv6 types differs from ICMPv4. */ if (type == ICMP6_ECHO_REQUEST || type == ICMP6_ECHO_REPLY) { nat64_icmp_handle_echo(ip6, ICMP6(icmp), icmpid, type); return (m); } /* * For other types of ICMP messages we need to translate inner * IPv4 header to IPv6 header. * Assume ICMP src is the same as payload dst * E.g. we have ( GWsrc1 , NATIP1 ) in outer header * and ( NATIP1, Hostdst1 ) in ICMP copy header. * In that case, we already have map for NATIP1 and GWsrc1. * The only thing we need is to copy IPv6 map prefix to * Hostdst1. */ hlen = offset + ICMP_MINLEN; if (m->m_pkthdr.len < hlen + sizeof(struct ip) + ICMP_MINLEN) { DPRINTF(DP_DROPS, "Message is too short %d", m->m_pkthdr.len); goto freeit; } m_copydata(m, hlen, sizeof(struct ip), (char *)&ip); if (ip.ip_v != IPVERSION) { DPRINTF(DP_DROPS, "Wrong IP version %d", ip.ip_v); goto freeit; } hlen += ip.ip_hl << 2; /* Skip inner IP header */ if (nat64_check_ip4(ip.ip_src.s_addr) != 0 || nat64_check_ip4(ip.ip_dst.s_addr) != 0 || nat64_check_private_ip4(cfg, ip.ip_src.s_addr) != 0 || nat64_check_private_ip4(cfg, ip.ip_dst.s_addr) != 0) { DPRINTF(DP_DROPS, "IP addresses checks failed %04x -> %04x", ntohl(ip.ip_src.s_addr), ntohl(ip.ip_dst.s_addr)); goto freeit; } if (m->m_pkthdr.len < hlen + ICMP_MINLEN) { DPRINTF(DP_DROPS, "Message is too short %d", m->m_pkthdr.len); goto freeit; } #if 0 /* * Check that inner source matches the outer destination. * XXX: We need some method to convert IPv4 into IPv6 address here, * and compare IPv6 addresses. */ if (ip.ip_src.s_addr != nat64_get_ip4(&ip6->ip6_dst)) { DPRINTF(DP_GENERIC, "Inner source doesn't match destination ", "%04x vs %04x", ip.ip_src.s_addr, nat64_get_ip4(&ip6->ip6_dst)); goto freeit; } #endif /* * Create new mbuf for ICMPv6 datagram. * NOTE: len is data length just after inner IP header. */ len = m->m_pkthdr.len - hlen; if (sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr) + len > NAT64_ICMP6_PLEN) len = NAT64_ICMP6_PLEN - sizeof(struct icmp6_hdr) - sizeof(struct ip6_hdr); plen = sizeof(struct icmp6_hdr) + sizeof(struct ip6_hdr) + len; n = m_get2(offset + plen + max_hdr, M_NOWAIT, MT_HEADER, M_PKTHDR); if (n == NULL) { NAT64STAT_INC(&cfg->stats, nomem); m_freem(m); return (NULL); } m_move_pkthdr(n, m); M_ALIGN(n, offset + plen + max_hdr); n->m_len = n->m_pkthdr.len = offset + plen; /* Adjust ip6_plen in outer header */ ip6->ip6_plen = htons(plen); /* Construct new inner IPv6 header */ eip6 = mtodo(n, offset + sizeof(struct icmp6_hdr)); eip6->ip6_src = ip6->ip6_dst; /* Use the same prefix that we have in outer header */ eip6->ip6_dst = ip6->ip6_src; MPASS(cfg->flags & NAT64_PLATPFX); nat64_embed_ip4(&eip6->ip6_dst, cfg->plat_plen, ip.ip_dst.s_addr); eip6->ip6_flow = htonl(ip.ip_tos << 20); eip6->ip6_vfc |= IPV6_VERSION; eip6->ip6_hlim = ip.ip_ttl; eip6->ip6_plen = htons(ntohs(ip.ip_len) - (ip.ip_hl << 2)); eip6->ip6_nxt = (ip.ip_p == IPPROTO_ICMP) ? IPPROTO_ICMPV6: ip.ip_p; m_copydata(m, hlen, len, (char *)(eip6 + 1)); /* * We need to translate source port in the inner ULP header, * and adjust ULP checksum. */ switch (ip.ip_p) { case IPPROTO_TCP: if (len < offsetof(struct tcphdr, th_sum)) break; tcp = TCP(eip6 + 1); if (icmpid != 0) { tcp->th_sum = cksum_adjust(tcp->th_sum, tcp->th_sport, icmpid); tcp->th_sport = icmpid; } tcp->th_sum = cksum_add(tcp->th_sum, ~nat64_cksum_convert(eip6, &ip)); break; case IPPROTO_UDP: if (len < offsetof(struct udphdr, uh_sum)) break; udp = UDP(eip6 + 1); if (icmpid != 0) { udp->uh_sum = cksum_adjust(udp->uh_sum, udp->uh_sport, icmpid); udp->uh_sport = icmpid; } udp->uh_sum = cksum_add(udp->uh_sum, ~nat64_cksum_convert(eip6, &ip)); break; case IPPROTO_ICMP: /* * Check if this is an ICMP error message for echo request * that we sent. I.e. ULP in the data containing invoking * packet is IPPROTO_ICMP and its type is ICMP_ECHO. */ icmp = (struct icmp *)(eip6 + 1); if (icmp->icmp_type != ICMP_ECHO) { m_freem(n); goto freeit; } /* * For our client this original datagram should looks * like it was ICMPv6 datagram with type ICMP6_ECHO_REQUEST. * Thus we need adjust icmp_cksum and convert type from * ICMP_ECHO to ICMP6_ECHO_REQUEST. */ nat64_icmp_handle_echo(eip6, ICMP6(icmp), icmpid, ICMP6_ECHO_REQUEST); } m_freem(m); /* Convert ICMPv4 into ICMPv6 header */ icmp = mtodo(n, offset); ICMP6(icmp)->icmp6_type = type; ICMP6(icmp)->icmp6_code = code; ICMP6(icmp)->icmp6_mtu = htonl(mtu); ICMP6(icmp)->icmp6_cksum = 0; ICMP6(icmp)->icmp6_cksum = cksum_add( ~in6_cksum_pseudo(ip6, plen, IPPROTO_ICMPV6, 0), in_cksum_skip(n, n->m_pkthdr.len, offset)); return (n); freeit: m_freem(m); NAT64STAT_INC(&cfg->stats, dropped); return (NULL); } int nat64_getlasthdr(struct mbuf *m, int *offset) { struct ip6_hdr *ip6; struct ip6_hbh *hbh; int proto, hlen; if (offset != NULL) hlen = *offset; else hlen = 0; if (m->m_len < hlen + sizeof(*ip6)) return (-1); ip6 = mtodo(m, hlen); hlen += sizeof(*ip6); proto = ip6->ip6_nxt; /* Skip extension headers */ while (proto == IPPROTO_HOPOPTS || proto == IPPROTO_ROUTING || proto == IPPROTO_DSTOPTS) { hbh = mtodo(m, hlen); /* * We expect mbuf has contigious data up to * upper level header. */ if (m->m_len < hlen) return (-1); /* * We doesn't support Jumbo payload option, * so return error. */ if (proto == IPPROTO_HOPOPTS && ip6->ip6_plen == 0) return (-1); proto = hbh->ip6h_nxt; hlen += (hbh->ip6h_len + 1) << 3; } if (offset != NULL) *offset = hlen; return (proto); } int nat64_do_handle_ip4(struct mbuf *m, struct in6_addr *saddr, struct in6_addr *daddr, uint16_t lport, struct nat64_config *cfg, void *logdata) { struct nhop_object *nh; struct ip6_hdr ip6; struct sockaddr_in6 dst; struct ip *ip; struct mbufq mq; uint16_t ip_id, ip_off; uint16_t *csum; int plen, hlen; uint8_t proto; ip = mtod(m, struct ip*); if (*V_nat64ipstealth == 0 && ip->ip_ttl <= IPTTLDEC) { nat64_icmp_reflect(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, &cfg->stats, logdata); return (NAT64RETURN); } ip6.ip6_dst = *daddr; ip6.ip6_src = *saddr; hlen = ip->ip_hl << 2; plen = ntohs(ip->ip_len) - hlen; proto = ip->ip_p; /* Save ip_id and ip_off, both are in network byte order */ ip_id = ip->ip_id; ip_off = ip->ip_off & htons(IP_OFFMASK | IP_MF); /* Fragment length must be multiple of 8 octets */ if ((ip->ip_off & htons(IP_MF)) != 0 && (plen & 0x7) != 0) { nat64_icmp_reflect(m, ICMP_PARAMPROB, ICMP_PARAMPROB_LENGTH, 0, &cfg->stats, logdata); return (NAT64RETURN); } /* Fragmented ICMP is unsupported */ if (proto == IPPROTO_ICMP && ip_off != 0) { DPRINTF(DP_DROPS, "dropped due to fragmented ICMP"); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } dst.sin6_addr = ip6.ip6_dst; nh = nat64_find_route6(&dst, m); if (nh == NULL) { NAT64STAT_INC(&cfg->stats, noroute6); nat64_icmp_reflect(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, &cfg->stats, logdata); return (NAT64RETURN); } if (nh->nh_mtu < plen + sizeof(ip6) && (ip->ip_off & htons(IP_DF)) != 0) { nat64_icmp_reflect(m, ICMP_UNREACH, ICMP_UNREACH_NEEDFRAG, FRAGSZ(nh->nh_mtu) + sizeof(struct ip), &cfg->stats, logdata); return (NAT64RETURN); } ip6.ip6_flow = htonl(ip->ip_tos << 20); ip6.ip6_vfc |= IPV6_VERSION; ip6.ip6_hlim = ip->ip_ttl; if (*V_nat64ipstealth == 0) ip6.ip6_hlim -= IPTTLDEC; ip6.ip6_plen = htons(plen); ip6.ip6_nxt = (proto == IPPROTO_ICMP) ? IPPROTO_ICMPV6: proto; /* Handle delayed checksums if needed. */ if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { in_delayed_cksum(m); m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; } /* Convert checksums. */ switch (proto) { case IPPROTO_TCP: csum = &TCP(mtodo(m, hlen))->th_sum; if (lport != 0) { struct tcphdr *tcp = TCP(mtodo(m, hlen)); *csum = cksum_adjust(*csum, tcp->th_dport, lport); tcp->th_dport = lport; } *csum = cksum_add(*csum, ~nat64_cksum_convert(&ip6, ip)); break; case IPPROTO_UDP: csum = &UDP(mtodo(m, hlen))->uh_sum; if (lport != 0) { struct udphdr *udp = UDP(mtodo(m, hlen)); *csum = cksum_adjust(*csum, udp->uh_dport, lport); udp->uh_dport = lport; } *csum = cksum_add(*csum, ~nat64_cksum_convert(&ip6, ip)); break; case IPPROTO_ICMP: m = nat64_icmp_translate(m, &ip6, lport, hlen, cfg); if (m == NULL) /* stats already accounted */ return (NAT64RETURN); } m_adj(m, hlen); mbufq_init(&mq, 255); nat64_fragment6(&cfg->stats, &ip6, &mq, m, nh->nh_mtu, ip_id, ip_off); while ((m = mbufq_dequeue(&mq)) != NULL) { if (V_nat64out->output(nh->nh_ifp, m, (struct sockaddr *)&dst, &cfg->stats, logdata) != 0) break; NAT64STAT_INC(&cfg->stats, opcnt46); } mbufq_drain(&mq); return (NAT64RETURN); } int nat64_handle_icmp6(struct mbuf *m, int hlen, uint32_t aaddr, uint16_t aport, struct nat64_config *cfg, void *logdata) { struct ip ip; struct icmp6_hdr *icmp6; struct ip6_frag *ip6f; struct ip6_hdr *ip6, *ip6i; uint32_t mtu; int plen, proto; uint8_t type, code; if (hlen == 0) { ip6 = mtod(m, struct ip6_hdr *); if (nat64_check_ip6(&ip6->ip6_src) != 0 || nat64_check_ip6(&ip6->ip6_dst) != 0) return (NAT64SKIP); proto = nat64_getlasthdr(m, &hlen); if (proto != IPPROTO_ICMPV6) { DPRINTF(DP_DROPS, "dropped due to mbuf isn't contigious"); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } } /* * Translate ICMPv6 type and code to ICMPv4 (RFC7915). * NOTE: ICMPv6 echo handled by nat64_do_handle_ip6(). */ icmp6 = mtodo(m, hlen); mtu = 0; switch (icmp6->icmp6_type) { case ICMP6_DST_UNREACH: type = ICMP_UNREACH; switch (icmp6->icmp6_code) { case ICMP6_DST_UNREACH_NOROUTE: case ICMP6_DST_UNREACH_BEYONDSCOPE: case ICMP6_DST_UNREACH_ADDR: code = ICMP_UNREACH_HOST; break; case ICMP6_DST_UNREACH_ADMIN: code = ICMP_UNREACH_HOST_PROHIB; break; case ICMP6_DST_UNREACH_NOPORT: code = ICMP_UNREACH_PORT; break; default: DPRINTF(DP_DROPS, "Unsupported ICMPv6 type %d," " code %d", icmp6->icmp6_type, icmp6->icmp6_code); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } break; case ICMP6_PACKET_TOO_BIG: type = ICMP_UNREACH; code = ICMP_UNREACH_NEEDFRAG; mtu = ntohl(icmp6->icmp6_mtu); if (mtu < IPV6_MMTU) { DPRINTF(DP_DROPS, "Wrong MTU %d in ICMPv6 type %d," " code %d", mtu, icmp6->icmp6_type, icmp6->icmp6_code); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } /* * Adjust MTU to reflect difference between * IPv6 an IPv4 headers. */ mtu -= sizeof(struct ip6_hdr) - sizeof(struct ip); break; case ICMP6_TIME_EXCEEDED: type = ICMP_TIMXCEED; code = icmp6->icmp6_code; break; case ICMP6_PARAM_PROB: switch (icmp6->icmp6_code) { case ICMP6_PARAMPROB_HEADER: type = ICMP_PARAMPROB; code = ICMP_PARAMPROB_ERRATPTR; mtu = ntohl(icmp6->icmp6_pptr); switch (mtu) { case 0: /* Version/Traffic Class */ case 1: /* Traffic Class/Flow Label */ break; case 4: /* Payload Length */ case 5: mtu = 2; break; case 6: /* Next Header */ mtu = 9; break; case 7: /* Hop Limit */ mtu = 8; break; default: if (mtu >= 8 && mtu <= 23) { mtu = 12; /* Source address */ break; } if (mtu >= 24 && mtu <= 39) { mtu = 16; /* Destination address */ break; } DPRINTF(DP_DROPS, "Unsupported ICMPv6 type %d," " code %d, pptr %d", icmp6->icmp6_type, icmp6->icmp6_code, mtu); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } case ICMP6_PARAMPROB_NEXTHEADER: type = ICMP_UNREACH; code = ICMP_UNREACH_PROTOCOL; break; default: DPRINTF(DP_DROPS, "Unsupported ICMPv6 type %d," " code %d, pptr %d", icmp6->icmp6_type, icmp6->icmp6_code, ntohl(icmp6->icmp6_pptr)); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } break; default: DPRINTF(DP_DROPS, "Unsupported ICMPv6 type %d, code %d", icmp6->icmp6_type, icmp6->icmp6_code); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } hlen += sizeof(struct icmp6_hdr); if (m->m_pkthdr.len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) { NAT64STAT_INC(&cfg->stats, dropped); DPRINTF(DP_DROPS, "Message is too short %d", m->m_pkthdr.len); return (NAT64MFREE); } /* * We need at least ICMP_MINLEN bytes of original datagram payload * to generate ICMP message. It is nice that ICMP_MINLEN is equal * to sizeof(struct ip6_frag). So, if embedded datagram had a fragment * header we will not have to do m_pullup() again. * * What we have here: * Outer header: (IPv6iGW, v4mapPRefix+v4exthost) * Inner header: (v4mapPRefix+v4host, IPv6iHost) [sport, dport] * We need to translate it to: * * Outer header: (alias_host, v4exthost) * Inner header: (v4exthost, alias_host) [sport, alias_port] * * Assume caller function has checked if v4mapPRefix+v4host * matches configured prefix. * The only two things we should be provided with are mapping between * IPv6iHost <> alias_host and between dport and alias_port. */ if (m->m_len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) m = m_pullup(m, hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN); if (m == NULL) { NAT64STAT_INC(&cfg->stats, nomem); return (NAT64RETURN); } ip6 = mtod(m, struct ip6_hdr *); ip6i = mtodo(m, hlen); ip6f = NULL; proto = ip6i->ip6_nxt; plen = ntohs(ip6i->ip6_plen); hlen += sizeof(struct ip6_hdr); if (proto == IPPROTO_FRAGMENT) { if (m->m_pkthdr.len < hlen + sizeof(struct ip6_frag) + ICMP_MINLEN) goto fail; ip6f = mtodo(m, hlen); proto = ip6f->ip6f_nxt; plen -= sizeof(struct ip6_frag); hlen += sizeof(struct ip6_frag); /* Ajust MTU to reflect frag header size */ if (type == ICMP_UNREACH && code == ICMP_UNREACH_NEEDFRAG) mtu -= sizeof(struct ip6_frag); } if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) { DPRINTF(DP_DROPS, "Unsupported proto %d in the inner header", proto); goto fail; } if (nat64_check_ip6(&ip6i->ip6_src) != 0 || nat64_check_ip6(&ip6i->ip6_dst) != 0) { DPRINTF(DP_DROPS, "Inner addresses do not passes the check"); goto fail; } /* Check if outer dst is the same as inner src */ if (!IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6i->ip6_src)) { DPRINTF(DP_DROPS, "Inner src doesn't match outer dst"); goto fail; } /* Now we need to make a fake IPv4 packet to generate ICMP message */ ip.ip_dst.s_addr = aaddr; ip.ip_src.s_addr = nat64_extract_ip4(&ip6i->ip6_src, cfg->plat_plen); if (ip.ip_src.s_addr == 0) goto fail; /* XXX: Make fake ulp header */ if (V_nat64out == &nat64_direct) /* init_ip4hdr will decrement it */ ip6i->ip6_hlim += IPV6_HLIMDEC; nat64_init_ip4hdr(ip6i, ip6f, plen, proto, &ip); m_adj(m, hlen - sizeof(struct ip)); bcopy(&ip, mtod(m, void *), sizeof(ip)); nat64_icmp_reflect(m, type, code, (uint16_t)mtu, &cfg->stats, logdata); return (NAT64RETURN); fail: /* * We must call m_freem() because mbuf pointer could be * changed with m_pullup(). */ m_freem(m); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64RETURN); } int nat64_do_handle_ip6(struct mbuf *m, uint32_t aaddr, uint16_t aport, struct nat64_config *cfg, void *logdata) { struct ip ip; struct nhop_object *nh; struct sockaddr_in dst; struct ip6_frag *frag; struct ip6_hdr *ip6; struct icmp6_hdr *icmp6; uint16_t *csum; int plen, hlen, proto; /* * XXX: we expect ipfw_chk() did m_pullup() up to upper level * protocol's headers. Also we skip some checks, that ip6_input(), * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did. */ ip6 = mtod(m, struct ip6_hdr *); if (nat64_check_ip6(&ip6->ip6_src) != 0 || nat64_check_ip6(&ip6->ip6_dst) != 0) { return (NAT64SKIP); } /* Starting from this point we must not return zero */ ip.ip_src.s_addr = aaddr; if (nat64_check_ip4(ip.ip_src.s_addr) != 0) { DPRINTF(DP_GENERIC | DP_DROPS, "invalid source address: %08x", ip.ip_src.s_addr); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } ip.ip_dst.s_addr = nat64_extract_ip4(&ip6->ip6_dst, cfg->plat_plen); if (ip.ip_dst.s_addr == 0) { NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } if (*V_nat64ip6stealth == 0 && ip6->ip6_hlim <= IPV6_HLIMDEC) { nat64_icmp6_reflect(m, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT, 0, &cfg->stats, logdata); return (NAT64RETURN); } hlen = 0; plen = ntohs(ip6->ip6_plen); proto = nat64_getlasthdr(m, &hlen); if (proto < 0) { DPRINTF(DP_DROPS, "dropped due to mbuf isn't contigious"); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } frag = NULL; if (proto == IPPROTO_FRAGMENT) { /* ipfw_chk should m_pullup up to frag header */ if (m->m_len < hlen + sizeof(*frag)) { DPRINTF(DP_DROPS, "dropped due to mbuf isn't contigious"); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } frag = mtodo(m, hlen); proto = frag->ip6f_nxt; hlen += sizeof(*frag); /* Fragmented ICMPv6 is unsupported */ if (proto == IPPROTO_ICMPV6) { DPRINTF(DP_DROPS, "dropped due to fragmented ICMPv6"); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } /* Fragment length must be multiple of 8 octets */ if ((frag->ip6f_offlg & IP6F_MORE_FRAG) != 0 && ((plen + sizeof(struct ip6_hdr) - hlen) & 0x7) != 0) { nat64_icmp6_reflect(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, offsetof(struct ip6_hdr, ip6_plen), &cfg->stats, logdata); return (NAT64RETURN); } } plen -= hlen - sizeof(struct ip6_hdr); if (plen < 0 || m->m_pkthdr.len < plen + hlen) { DPRINTF(DP_DROPS, "plen %d, pkthdr.len %d, hlen %d", plen, m->m_pkthdr.len, hlen); NAT64STAT_INC(&cfg->stats, dropped); return (NAT64MFREE); } icmp6 = NULL; /* Make gcc happy */ if (proto == IPPROTO_ICMPV6) { icmp6 = mtodo(m, hlen); if (icmp6->icmp6_type != ICMP6_ECHO_REQUEST && icmp6->icmp6_type != ICMP6_ECHO_REPLY) return (nat64_handle_icmp6(m, hlen, aaddr, aport, cfg, logdata)); } dst.sin_addr.s_addr = ip.ip_dst.s_addr; nh = nat64_find_route4(&dst, m); if (nh == NULL) { NAT64STAT_INC(&cfg->stats, noroute4); nat64_icmp6_reflect(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE, 0, &cfg->stats, logdata); return (NAT64RETURN); } if (nh->nh_mtu < plen + sizeof(ip)) { nat64_icmp6_reflect(m, ICMP6_PACKET_TOO_BIG, 0, nh->nh_mtu, &cfg->stats, logdata); return (NAT64RETURN); } nat64_init_ip4hdr(ip6, frag, plen, proto, &ip); /* Handle delayed checksums if needed. */ if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) { in6_delayed_cksum(m, plen, hlen); m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6; } /* Convert checksums. */ switch (proto) { case IPPROTO_TCP: csum = &TCP(mtodo(m, hlen))->th_sum; if (aport != 0) { struct tcphdr *tcp = TCP(mtodo(m, hlen)); *csum = cksum_adjust(*csum, tcp->th_sport, aport); tcp->th_sport = aport; } *csum = cksum_add(*csum, nat64_cksum_convert(ip6, &ip)); break; case IPPROTO_UDP: csum = &UDP(mtodo(m, hlen))->uh_sum; if (aport != 0) { struct udphdr *udp = UDP(mtodo(m, hlen)); *csum = cksum_adjust(*csum, udp->uh_sport, aport); udp->uh_sport = aport; } *csum = cksum_add(*csum, nat64_cksum_convert(ip6, &ip)); break; case IPPROTO_ICMPV6: /* Checksum in ICMPv6 covers pseudo header */ csum = &icmp6->icmp6_cksum; *csum = cksum_add(*csum, in6_cksum_pseudo(ip6, plen, IPPROTO_ICMPV6, 0)); /* Convert ICMPv6 types to ICMP */ proto = *(uint16_t *)icmp6; /* save old word for cksum_adjust */ if (icmp6->icmp6_type == ICMP6_ECHO_REQUEST) icmp6->icmp6_type = ICMP_ECHO; else /* ICMP6_ECHO_REPLY */ icmp6->icmp6_type = ICMP_ECHOREPLY; *csum = cksum_adjust(*csum, (uint16_t)proto, *(uint16_t *)icmp6); if (aport != 0) { uint16_t old_id = icmp6->icmp6_id; icmp6->icmp6_id = aport; *csum = cksum_adjust(*csum, old_id, aport); } break; }; m_adj(m, hlen - sizeof(ip)); bcopy(&ip, mtod(m, void *), sizeof(ip)); if (V_nat64out->output(nh->nh_ifp, m, (struct sockaddr *)&dst, &cfg->stats, logdata) == 0) NAT64STAT_INC(&cfg->stats, opcnt64); return (NAT64RETURN); }