nat64clat.c

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    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("$FreeBSD$");
   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 
   67 static void
   68 nat64clat_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_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 
   86 static int
   87 nat64clat_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 
  114 static int
  115 nat64clat_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 
  147 static int
  148 nat64clat_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 
  205 int
  206 ipfw_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 }

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FreeBSD/Linux Kernel Cross Reference sys/netpfil/ipfw/nat64/nat64clat.c

FreeBSD/Linux Kernel Cross Reference
sys/netpfil/ipfw/nat64/nat64clat.c