nat64clat.c revision 346212
1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2019 Yandex LLC 5 * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org> 6 * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com> 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30#include <sys/cdefs.h> 31__FBSDID("$FreeBSD: stable/11/sys/netpfil/ipfw/nat64/nat64clat.c 346212 2019-04-14 12:39:09Z ae $"); 32 33#include <sys/param.h> 34#include <sys/systm.h> 35#include <sys/counter.h> 36#include <sys/kernel.h> 37#include <sys/lock.h> 38#include <sys/mbuf.h> 39#include <sys/module.h> 40#include <sys/rmlock.h> 41#include <sys/rwlock.h> 42#include <sys/socket.h> 43#include <sys/sysctl.h> 44 45#include <net/if.h> 46#include <net/if_var.h> 47#include <net/if_pflog.h> 48#include <net/pfil.h> 49 50#include <netinet/in.h> 51#include <netinet/ip.h> 52#include <netinet/ip_icmp.h> 53#include <netinet/ip_var.h> 54#include <netinet/ip_fw.h> 55#include <netinet/ip6.h> 56#include <netinet/icmp6.h> 57#include <netinet6/ip_fw_nat64.h> 58 59#include <netpfil/ipfw/ip_fw_private.h> 60#include <netpfil/pf/pf.h> 61 62#include "nat64clat.h" 63 64#define NAT64_LOOKUP(chain, cmd) \ 65 (struct nat64clat_cfg *)SRV_OBJECT((chain), (cmd)->arg1) 66 67static void 68nat64clat_log(struct pfloghdr *plog, struct mbuf *m, sa_family_t family, 69 uint32_t kidx) 70{ 71 static uint32_t pktid = 0; 72 73 memset(plog, 0, sizeof(*plog)); 74 plog->length = PFLOG_REAL_HDRLEN; 75 plog->af = family; 76 plog->action = PF_NAT; 77 plog->dir = PF_IN; 78 plog->rulenr = htonl(kidx); 79 pktid++; 80 plog->subrulenr = htonl(pktid); 81 plog->ruleset[0] = '\0'; 82 strlcpy(plog->ifname, "NAT64CLAT", sizeof(plog->ifname)); 83 ipfw_bpf_mtap2(plog, PFLOG_HDRLEN, m); 84} 85 86static int 87nat64clat_handle_ip4(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg, 88 struct mbuf *m) 89{ 90 struct pfloghdr loghdr, *logdata; 91 struct in6_addr saddr, daddr; 92 struct ip *ip; 93 94 ip = mtod(m, struct ip*); 95 /* source address for CLAT may be private with no harm */ 96 if (nat64_check_ip4(ip->ip_src.s_addr) != 0 || 97 nat64_check_ip4(ip->ip_dst.s_addr) != 0 || 98 nat64_check_private_ip4(&cfg->base, ip->ip_dst.s_addr) != 0) 99 return (NAT64SKIP); 100 101 memcpy(&saddr, &cfg->base.clat_prefix, sizeof(saddr)); 102 nat64_embed_ip4(&saddr, cfg->base.clat_plen, ip->ip_src.s_addr); 103 memcpy(&daddr, &cfg->base.plat_prefix, sizeof(daddr)); 104 nat64_embed_ip4(&daddr, cfg->base.plat_plen, ip->ip_dst.s_addr); 105 if (cfg->base.flags & NAT64_LOG) { 106 logdata = &loghdr; 107 nat64clat_log(logdata, m, AF_INET, cfg->no.kidx); 108 } else 109 logdata = NULL; 110 return (nat64_do_handle_ip4(m, &saddr, &daddr, 0, &cfg->base, 111 logdata)); 112} 113 114static int 115nat64clat_handle_ip6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg, 116 struct mbuf *m) 117{ 118 struct pfloghdr loghdr, *logdata; 119 struct ip6_hdr *ip6; 120 uint32_t aaddr; 121 122 /* 123 * NOTE: we expect ipfw_chk() did m_pullup() up to upper level 124 * protocol's headers. Also we skip some checks, that ip6_input(), 125 * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did. 126 */ 127 ip6 = mtod(m, struct ip6_hdr *); 128 /* Check ip6_dst matches configured prefix */ 129 if (memcmp(&ip6->ip6_dst, &cfg->base.clat_prefix, 130 cfg->base.clat_plen / 8) != 0) 131 return (NAT64SKIP); 132 /* Check ip6_src matches configured prefix */ 133 if (memcmp(&ip6->ip6_src, &cfg->base.plat_prefix, 134 cfg->base.plat_plen / 8) != 0) 135 return (NAT64SKIP); 136 137 if (cfg->base.flags & NAT64_LOG) { 138 logdata = &loghdr; 139 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx); 140 } else 141 logdata = NULL; 142 143 aaddr = nat64_extract_ip4(&ip6->ip6_src, cfg->base.plat_plen); 144 return (nat64_do_handle_ip6(m, aaddr, 0, &cfg->base, logdata)); 145} 146 147static int 148nat64clat_handle_icmp6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg, 149 struct mbuf *m) 150{ 151 struct pfloghdr loghdr, *logdata; 152 struct nat64_counters *stats; 153 struct ip6_hdr *ip6i; 154 struct icmp6_hdr *icmp6; 155 uint32_t daddr; 156 int hlen, proto; 157 158 hlen = 0; 159 stats = &cfg->base.stats; 160 proto = nat64_getlasthdr(m, &hlen); 161 if (proto != IPPROTO_ICMPV6) { 162 NAT64STAT_INC(stats, dropped); 163 return (NAT64MFREE); 164 } 165 icmp6 = mtodo(m, hlen); 166 switch (icmp6->icmp6_type) { 167 case ICMP6_DST_UNREACH: 168 case ICMP6_PACKET_TOO_BIG: 169 case ICMP6_TIME_EXCEED_TRANSIT: 170 case ICMP6_PARAM_PROB: 171 break; 172 default: 173 NAT64STAT_INC(stats, dropped); 174 return (NAT64MFREE); 175 } 176 hlen += sizeof(struct icmp6_hdr); 177 if (m->m_pkthdr.len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) { 178 NAT64STAT_INC(stats, dropped); 179 return (NAT64MFREE); 180 } 181 if (m->m_len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) 182 m = m_pullup(m, hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN); 183 if (m == NULL) { 184 NAT64STAT_INC(stats, nomem); 185 return (NAT64RETURN); 186 } 187 /* 188 * Use destination address from inner IPv6 header to determine 189 * IPv4 mapped address. 190 */ 191 ip6i = mtodo(m, hlen); 192 daddr = nat64_extract_ip4(&ip6i->ip6_dst, cfg->base.clat_plen); 193 if (daddr == 0) { 194 NAT64STAT_INC(stats, dropped); 195 return (NAT64MFREE); 196 } 197 if (cfg->base.flags & NAT64_LOG) { 198 logdata = &loghdr; 199 nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx); 200 } else 201 logdata = NULL; 202 return (nat64_handle_icmp6(m, 0, daddr, 0, &cfg->base, logdata)); 203} 204 205int 206ipfw_nat64clat(struct ip_fw_chain *chain, struct ip_fw_args *args, 207 ipfw_insn *cmd, int *done) 208{ 209 ipfw_insn *icmd; 210 struct nat64clat_cfg *cfg; 211 int ret; 212 213 IPFW_RLOCK_ASSERT(chain); 214 215 *done = 0; /* try next rule if not matched */ 216 icmd = cmd + 1; 217 if (cmd->opcode != O_EXTERNAL_ACTION || 218 cmd->arg1 != V_nat64clat_eid || 219 icmd->opcode != O_EXTERNAL_INSTANCE || 220 (cfg = NAT64_LOOKUP(chain, icmd)) == NULL) 221 return (0); 222 223 switch (args->f_id.addr_type) { 224 case 4: 225 ret = nat64clat_handle_ip4(chain, cfg, args->m); 226 break; 227 case 6: 228 ret = nat64clat_handle_ip6(chain, cfg, args->m); 229 break; 230 default: 231 return (0); 232 } 233 234 if (ret == NAT64SKIP) { 235 /* 236 * In case when packet is ICMPv6 message from an intermediate 237 * router, the source address of message will not match the 238 * addresses from configured prefixes. 239 */ 240 if (args->f_id.proto != IPPROTO_ICMPV6) 241 return (0); 242 243 ret = nat64clat_handle_icmp6(chain, cfg, args->m); 244 } 245 246 if (ret == NAT64SKIP) 247 return (0); 248 249 *done = 1; /* terminate the search */ 250 if (ret == NAT64MFREE) 251 m_freem(args->m); 252 253 args->m = NULL; 254 return (IP_FW_NAT64); 255} 256