xnu-2422.1.72.tar.gz

[apple/xnu.git] / bsd / netinet6 / esp_input.c

/*
 * Copyright (c) 2008-2013 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

/*      $FreeBSD: src/sys/netinet6/esp_input.c,v 1.1.2.3 2001/07/03 11:01:50 ume Exp $  */
/*      $KAME: esp_input.c,v 1.55 2001/03/23 08:08:47 itojun Exp $      */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project 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 PROJECT 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 PROJECT 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.
 */

/*
 * RFC1827/2406 Encapsulated Security Payload.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mcache.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/route.h>
#include <kern/cpu_number.h>
#include <kern/locks.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/in_var.h>
#include <netinet/ip_ecn.h>
#include <netinet/in_pcb.h>
#include <netinet/udp.h>
#if INET6
#include <netinet6/ip6_ecn.h>
#endif

#if INET6
#include <netinet/ip6.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/ip6protosw.h>
#endif

#include <netinet6/ipsec.h>
#if INET6
#include <netinet6/ipsec6.h>
#endif
#include <netinet6/ah.h>
#if INET6
#include <netinet6/ah6.h>
#endif
#include <netinet6/esp.h>
#if INET6
#include <netinet6/esp6.h>
#endif
#include <netkey/key.h>
#include <netkey/keydb.h>
#include <netkey/key_debug.h>

#include <net/kpi_protocol.h>
#include <netinet/kpi_ipfilter_var.h>

#include <net/net_osdep.h>
#include <mach/sdt.h>

#include <sys/kdebug.h>
#define DBG_LAYER_BEG           NETDBG_CODE(DBG_NETIPSEC, 1)
#define DBG_LAYER_END           NETDBG_CODE(DBG_NETIPSEC, 3)
#define DBG_FNC_ESPIN           NETDBG_CODE(DBG_NETIPSEC, (6 << 8))
#define DBG_FNC_DECRYPT         NETDBG_CODE(DBG_NETIPSEC, (7 << 8))
#define IPLEN_FLIPPED

extern lck_mtx_t  *sadb_mutex;

#if INET
#define ESPMAXLEN \
        (sizeof(struct esp) < sizeof(struct newesp) \
                ? sizeof(struct newesp) : sizeof(struct esp))

static struct ip *
esp4_input_strip_UDP_encap (struct mbuf *m, int iphlen)
{
        // strip the udp header that's encapsulating ESP
        struct ip *ip;
        size_t     stripsiz = sizeof(struct udphdr);

        ip = mtod(m, __typeof__(ip));
        ovbcopy((caddr_t)ip, (caddr_t)(((u_char *)ip) + stripsiz), iphlen);
        m->m_data += stripsiz;
        m->m_len -= stripsiz;
        m->m_pkthdr.len -= stripsiz;
        ip = mtod(m, __typeof__(ip));
        ip->ip_len = ip->ip_len - stripsiz;
        ip->ip_p = IPPROTO_ESP;
        return ip;
}

void
esp4_input(m, off)
        struct mbuf *m;
        int off;
{
        struct ip *ip;
#if INET6
        struct ip6_hdr *ip6;
#endif /* INET6 */
        struct esp *esp;
        struct esptail esptail;
        u_int32_t spi;
        u_int32_t seq;
        struct secasvar *sav = NULL;
        size_t taillen;
        u_int16_t nxt;
        const struct esp_algorithm *algo;
        int ivlen;
        size_t hlen;
        size_t esplen;
        sa_family_t     ifamily;

        KERNEL_DEBUG(DBG_FNC_ESPIN | DBG_FUNC_START, 0,0,0,0,0);
        /* sanity check for alignment. */
        if (off % 4 != 0 || m->m_pkthdr.len % 4 != 0) {
                ipseclog((LOG_ERR, "IPv4 ESP input: packet alignment problem "
                        "(off=%d, pktlen=%d)\n", off, m->m_pkthdr.len));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        if (m->m_len < off + ESPMAXLEN) {
                m = m_pullup(m, off + ESPMAXLEN);
                if (!m) {
                        ipseclog((LOG_DEBUG,
                            "IPv4 ESP input: can't pullup in esp4_input\n"));
                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                        goto bad;
                }
        }

        /* Expect 32-bit aligned data pointer on strict-align platforms */
        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

        ip = mtod(m, struct ip *);
        // expect udp-encap and esp packets only
        if (ip->ip_p != IPPROTO_ESP &&
            !(ip->ip_p == IPPROTO_UDP && off >= sizeof(struct udphdr))) {
                ipseclog((LOG_DEBUG,
                          "IPv4 ESP input: invalid protocol type\n"));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }
        esp = (struct esp *)(void *)(((u_int8_t *)ip) + off);
#ifdef _IP_VHL
        hlen = IP_VHL_HL(ip->ip_vhl) << 2;
#else
        hlen = ip->ip_hl << 2;
#endif

        /* find the sassoc. */
        spi = esp->esp_spi;

        if ((sav = key_allocsa(AF_INET,
                              (caddr_t)&ip->ip_src, (caddr_t)&ip->ip_dst,
                              IPPROTO_ESP, spi)) == 0) {
                ipseclog((LOG_WARNING,
                    "IPv4 ESP input: no key association found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_nosa);
                goto bad;
        }
        KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
            printf("DP esp4_input called to allocate SA:0x%llx\n",
            (uint64_t)VM_KERNEL_ADDRPERM(sav)));
        if (sav->state != SADB_SASTATE_MATURE
         && sav->state != SADB_SASTATE_DYING) {
                ipseclog((LOG_DEBUG,
                    "IPv4 ESP input: non-mature/dying SA found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_badspi);
                goto bad;
        }
        algo = esp_algorithm_lookup(sav->alg_enc);
        if (!algo) {
                ipseclog((LOG_DEBUG, "IPv4 ESP input: "
                    "unsupported encryption algorithm for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_badspi);
                goto bad;
        }

        /* check if we have proper ivlen information */
        ivlen = sav->ivlen;
        if (ivlen < 0) {
                ipseclog((LOG_ERR, "inproper ivlen in IPv4 ESP input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        seq = ntohl(((struct newesp *)esp)->esp_seq);
        if (!((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay
         && (sav->alg_auth && sav->key_auth)))
                goto noreplaycheck;

        if (sav->alg_auth == SADB_X_AALG_NULL ||
            sav->alg_auth == SADB_AALG_NONE)
                goto noreplaycheck;

        /*
         * check for sequence number.
         */
        if (ipsec_chkreplay(seq, sav))
                ; /*okey*/
        else {
                IPSEC_STAT_INCREMENT(ipsecstat.in_espreplay);
                ipseclog((LOG_WARNING,
                    "replay packet in IPv4 ESP input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                goto bad;
        }

        /* check ICV */
    {
        u_char sum0[AH_MAXSUMSIZE] __attribute__((aligned(4)));
        u_char sum[AH_MAXSUMSIZE] __attribute__((aligned(4)));
        const struct ah_algorithm *sumalgo;
        size_t siz;

        sumalgo = ah_algorithm_lookup(sav->alg_auth);
        if (!sumalgo)
                goto noreplaycheck;
        siz = (((*sumalgo->sumsiz)(sav) + 3) & ~(4 - 1));
        if (m->m_pkthdr.len < off + ESPMAXLEN + siz) {
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }
        if (AH_MAXSUMSIZE < siz) {
                ipseclog((LOG_DEBUG,
                    "internal error: AH_MAXSUMSIZE must be larger than %lu\n",
                    (u_int32_t)siz));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        m_copydata(m, m->m_pkthdr.len - siz, siz, (caddr_t) &sum0[0]);

        if (esp_auth(m, off, m->m_pkthdr.len - off - siz, sav, sum)) {
                ipseclog((LOG_WARNING, "auth fail in IPv4 ESP input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_espauthfail);
                goto bad;
        }

        if (bcmp(sum0, sum, siz) != 0) {
                ipseclog((LOG_WARNING, "auth fail in IPv4 ESP input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_espauthfail);
                goto bad;
        }

        /* strip off the authentication data */
        m_adj(m, -siz);
        ip = mtod(m, struct ip *);
#ifdef IPLEN_FLIPPED
        ip->ip_len = ip->ip_len - siz;
#else
        ip->ip_len = htons(ntohs(ip->ip_len) - siz);
#endif
        m->m_flags |= M_AUTHIPDGM;
        IPSEC_STAT_INCREMENT(ipsecstat.in_espauthsucc);
    }

        /*
         * update sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_updatereplay(seq, sav)) {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_espreplay);
                        goto bad;
                }
        }

noreplaycheck:

        /* process main esp header. */
        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1827 */
                esplen = sizeof(struct esp);
        } else {
                /* RFC 2406 */
                if (sav->flags & SADB_X_EXT_DERIV)
                        esplen = sizeof(struct esp);
                else
                        esplen = sizeof(struct newesp);
        }

        if (m->m_pkthdr.len < off + esplen + ivlen + sizeof(esptail)) {
                ipseclog((LOG_WARNING,
                    "IPv4 ESP input: packet too short\n"));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        if (m->m_len < off + esplen + ivlen) {
                m = m_pullup(m, off + esplen + ivlen);
                if (!m) {
                        ipseclog((LOG_DEBUG,
                            "IPv4 ESP input: can't pullup in esp4_input\n"));
                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                        goto bad;
                }
        }

        /*
         * pre-compute and cache intermediate key
         */
        if (esp_schedule(algo, sav) != 0) {
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        /*
         * decrypt the packet.
         */
        if (!algo->decrypt)
                panic("internal error: no decrypt function");
        KERNEL_DEBUG(DBG_FNC_DECRYPT | DBG_FUNC_START, 0,0,0,0,0);
        if ((*algo->decrypt)(m, off, sav, algo, ivlen)) {
                /* m is already freed */
                m = NULL;
                ipseclog((LOG_ERR, "decrypt fail in IPv4 ESP input: %s\n",
                    ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                KERNEL_DEBUG(DBG_FNC_DECRYPT | DBG_FUNC_END, 1,0,0,0,0);
                goto bad;
        }
        KERNEL_DEBUG(DBG_FNC_DECRYPT | DBG_FUNC_END, 2,0,0,0,0);
        IPSEC_STAT_INCREMENT(ipsecstat.in_esphist[sav->alg_enc]);

        m->m_flags |= M_DECRYPTED;

        /*
         * find the trailer of the ESP.
         */
        m_copydata(m, m->m_pkthdr.len - sizeof(esptail), sizeof(esptail),
             (caddr_t)&esptail);
        nxt = esptail.esp_nxt;
        taillen = esptail.esp_padlen + sizeof(esptail);

        if (m->m_pkthdr.len < taillen
         || m->m_pkthdr.len - taillen < hlen) { /*?*/
                ipseclog((LOG_WARNING,
                    "bad pad length in IPv4 ESP input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }

        /* strip off the trailing pad area. */
        m_adj(m, -taillen);
        ip = mtod(m, struct ip *);
#ifdef IPLEN_FLIPPED
        ip->ip_len = ip->ip_len - taillen;
#else
        ip->ip_len = htons(ntohs(ip->ip_len) - taillen);
#endif
        if (ip->ip_p == IPPROTO_UDP) {
                // offset includes the outer ip and udp header lengths.
                if (m->m_len < off) {
                        m = m_pullup(m, off);
                        if (!m) {
                                ipseclog((LOG_DEBUG,
                                          "IPv4 ESP input: invalid udp encapsulated ESP packet length \n"));
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto bad;
                        }
                }

                // check the UDP encap header to detect changes in the source port, and then strip the header
                off -= sizeof(struct udphdr); // off no longer includes the udphdr's size
                // if peer is behind nat and this is the latest esp packet
                if ((sav->flags & SADB_X_EXT_NATT_DETECTED_PEER) != 0 &&
                    (sav->flags & SADB_X_EXT_OLD) == 0 &&
                    seq && sav->replay &&
                    seq >= sav->replay->lastseq)  {
                        struct udphdr *encap_uh = (__typeof__(encap_uh))(void *)((caddr_t)ip + off);
                        if (encap_uh->uh_sport &&
                            ntohs(encap_uh->uh_sport) != sav->remote_ike_port) {
                                sav->remote_ike_port = ntohs(encap_uh->uh_sport);
                        }
                }
                ip = esp4_input_strip_UDP_encap(m, off);
                esp = (struct esp *)(void *)(((u_int8_t *)ip) + off);
        }

        if (sav->utun_is_keepalive_fn) {
                if (sav->utun_is_keepalive_fn(sav->utun_pcb, &m, nxt, sav->flags, (off + esplen + ivlen))) {
                        if (m) {
                                // not really bad, we just wanna exit
                                IPSEC_STAT_INCREMENT(ipsecstat.in_success);
                                m = NULL;
                        }
                        goto bad;
                }
        }

        /* was it transmitted over the IPsec tunnel SA? */
        if (ipsec4_tunnel_validate(m, off + esplen + ivlen, nxt, sav, &ifamily)) {
                ifaddr_t ifa;
                struct sockaddr_storage addr;

                /*
                 * strip off all the headers that precedes ESP header.
                 *      IP4 xx ESP IP4' payload -> IP4' payload
                 *
                 * XXX more sanity checks
                 * XXX relationship with gif?
                 */
                u_int8_t tos;

                tos = ip->ip_tos;
                m_adj(m, off + esplen + ivlen);
                if (ifamily == AF_INET) {
                        struct sockaddr_in *ipaddr;

                        if (m->m_len < sizeof(*ip)) {
                                m = m_pullup(m, sizeof(*ip));
                                if (!m) {
                                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                        goto bad;
                                }
                        }
                        ip = mtod(m, struct ip *);
                        /* ECN consideration. */
                        ip_ecn_egress(ip4_ipsec_ecn, &tos, &ip->ip_tos);
                        if (!key_checktunnelsanity(sav, AF_INET,
                            (caddr_t)&ip->ip_src, (caddr_t)&ip->ip_dst)) {
                                ipseclog((LOG_ERR, "ipsec tunnel address mismatch "
                            "in ESP input: %s %s\n",
                            ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto bad;
                        }

                        if (ip_doscopedroute) {
                                bzero(&addr, sizeof(addr));
                                ipaddr = (__typeof__(ipaddr))&addr;
                                ipaddr->sin_family = AF_INET;
                                ipaddr->sin_len = sizeof(*ipaddr);
                                ipaddr->sin_addr = ip->ip_dst;
                        }
#if INET6
                } else if (ifamily == AF_INET6) {
                        struct sockaddr_in6 *ip6addr;

#ifndef PULLDOWN_TEST
                        /*
                         * m_pullup is prohibited in KAME IPv6 input processing
                         * but there's no other way!
                         */
#else
                        /* okay to pullup in m_pulldown style */
#endif
                        if (m->m_len < sizeof(*ip6)) {
                                m = m_pullup(m, sizeof(*ip6));
                                if (!m) {
                                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                        goto bad;
                                }
                        }

                        /*
                         * Expect 32-bit aligned data pointer on strict-align
                         * platforms.
                         */
                        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

                        ip6 = mtod(m, struct ip6_hdr *);

                        /* ECN consideration. */
                        /* XXX To be fixed later if needed */
                        //  ip_ecn_egress(ip4_ipsec_ecn, &tos, &ip->ip_tos);

                        if (!key_checktunnelsanity(sav, AF_INET6,
                            (caddr_t)&ip6->ip6_src, (caddr_t)&ip6->ip6_dst)) {
                                ipseclog((LOG_ERR, "ipsec tunnel address mismatch "
                            "in ESP input: %s %s\n",
                            ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto bad;
                        }

                        if (ip6_doscopedroute) {
                                bzero(&addr, sizeof(addr));
                                ip6addr = (__typeof__(ip6addr))&addr;
                                ip6addr->sin6_family = AF_INET6;
                                ip6addr->sin6_len = sizeof(*ip6addr);
                                ip6addr->sin6_addr = ip6->ip6_dst;
                        }
#endif /* INET6 */
                } else {
                        ipseclog((LOG_ERR, "ipsec tunnel unsupported address family "
                                  "in ESP input\n"));
                        goto bad;
                }

                key_sa_recordxfer(sav, m);
                if (ipsec_addhist(m, IPPROTO_ESP, spi) != 0 ||
                    ipsec_addhist(m, IPPROTO_IPV4, 0) != 0) {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_nomem);
                        goto bad;
                }

                if (ip_doscopedroute || ip6_doscopedroute) {
                        // update the receiving interface address based on the inner address
                        ifa = ifa_ifwithaddr((struct sockaddr *)&addr);
                        if (ifa) {
                                m->m_pkthdr.rcvif = ifa->ifa_ifp;
                                IFA_REMREF(ifa);
                        }
                }

                /* Clear the csum flags, they can't be valid for the inner headers */
                m->m_pkthdr.csum_flags = 0;

                if (sav->utun_in_fn) {
                        if (!(sav->utun_in_fn(sav->utun_pcb, &m, ifamily == AF_INET ? PF_INET : PF_INET6))) {
                                m = NULL;
                                // we just wanna exit since packet has been completely processed
                                goto bad;
                        }
                }

                if (proto_input(ifamily == AF_INET ? PF_INET : PF_INET6, m) != 0)
                        goto bad;

                nxt = IPPROTO_DONE;
                KERNEL_DEBUG(DBG_FNC_ESPIN | DBG_FUNC_END, 2,0,0,0,0);
        } else {
                /*
                 * strip off ESP header and IV.
                 * even in m_pulldown case, we need to strip off ESP so that
                 * we can always compute checksum for AH correctly.
                 */
                size_t stripsiz;

                stripsiz = esplen + ivlen;

                ip = mtod(m, struct ip *);
                ovbcopy((caddr_t)ip, (caddr_t)(((u_char *)ip) + stripsiz), off);
                m->m_data += stripsiz;
                m->m_len -= stripsiz;
                m->m_pkthdr.len -= stripsiz;

                ip = mtod(m, struct ip *);
#ifdef IPLEN_FLIPPED
                ip->ip_len = ip->ip_len - stripsiz;
#else
                ip->ip_len = htons(ntohs(ip->ip_len) - stripsiz);
#endif
                ip->ip_p = nxt;

                key_sa_recordxfer(sav, m);
                if (ipsec_addhist(m, IPPROTO_ESP, spi) != 0) {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_nomem);
                        goto bad;
                }
                
                /*
                 * Set the csum valid flag, if we authenticated the
                 * packet, the payload shouldn't be corrupt unless
                 * it was corrupted before being signed on the other
                 * side.
                 */
                if (nxt == IPPROTO_TCP || nxt == IPPROTO_UDP) {
                        m->m_pkthdr.csum_flags = CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
                        m->m_pkthdr.csum_data = 0xFFFF;
                }

                if (nxt != IPPROTO_DONE) {
                        if ((ip_protox[nxt]->pr_flags & PR_LASTHDR) != 0 &&
                            ipsec4_in_reject(m, NULL)) {
                                IPSEC_STAT_INCREMENT(ipsecstat.in_polvio);
                                goto bad;
                        }
                        KERNEL_DEBUG(DBG_FNC_ESPIN | DBG_FUNC_END, 3,0,0,0,0);
                        
                        /* translate encapsulated UDP port ? */
                        if ((sav->flags & SADB_X_EXT_NATT_MULTIPLEUSERS) != 0)  {
                                struct udphdr   *udp;
                                
                                if (nxt != IPPROTO_UDP) {       /* not UPD packet - drop it */
                                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                        goto bad;
                                }
                                        
                                if (m->m_len < off + sizeof(struct udphdr)) {
                                        m = m_pullup(m, off + sizeof(struct udphdr));
                                        if (!m) {
                                                ipseclog((LOG_DEBUG,
                                                        "IPv4 ESP input: can't pullup UDP header in esp4_input\n"));
                                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                                goto bad;
                                        }
                                        ip = mtod(m, struct ip *);
                                }
                                udp = (struct udphdr *)(void *)(((u_int8_t *)ip) + off);
                        
                                lck_mtx_lock(sadb_mutex);
                                if (sav->natt_encapsulated_src_port == 0) {     
                                        sav->natt_encapsulated_src_port = udp->uh_sport;
                                } else if (sav->natt_encapsulated_src_port != udp->uh_sport) {  /* something wrong */
                                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                        lck_mtx_unlock(sadb_mutex);
                                        goto bad;
                                }
                                lck_mtx_unlock(sadb_mutex);
                                udp->uh_sport = htons(sav->remote_ike_port);
                                udp->uh_sum = 0;
                        }

                        DTRACE_IP6(receive, struct mbuf *, m, struct inpcb *, NULL,
                                struct ip *, ip, struct ifnet *, m->m_pkthdr.rcvif,
                                struct ip *, ip, struct ip6_hdr *, NULL);

                        if (sav->utun_in_fn) {
                                if (!(sav->utun_in_fn(sav->utun_pcb, &m, PF_INET))) {
                                        m = NULL;
                                        // we just wanna exit since packet has been completely processed
                                        goto bad;
                                }
                        }

                        ip_proto_dispatch_in(m, off, nxt, 0);
                } else
                        m_freem(m);
                m = NULL;
        }

        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                    printf("DP esp4_input call free SA:0x%llx\n",
                    (uint64_t)VM_KERNEL_ADDRPERM(sav)));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        IPSEC_STAT_INCREMENT(ipsecstat.in_success);
        return;

bad:
        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                    printf("DP esp4_input call free SA:0x%llx\n",
                    (uint64_t)VM_KERNEL_ADDRPERM(sav)));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        if (m)
                m_freem(m);
        KERNEL_DEBUG(DBG_FNC_ESPIN | DBG_FUNC_END, 4,0,0,0,0);
        return;
}
#endif /* INET */

#if INET6
int
esp6_input(struct mbuf **mp, int *offp, int proto)
{
#pragma unused(proto)
        struct mbuf *m = *mp;
        int off = *offp;
        struct ip6_hdr *ip6;
        struct esp *esp;
        struct esptail esptail;
        u_int32_t spi;
        u_int32_t seq;
        struct secasvar *sav = NULL;
        size_t taillen;
        u_int16_t nxt;
        const struct esp_algorithm *algo;
        int ivlen;
        size_t esplen;

        /* sanity check for alignment. */
        if (off % 4 != 0 || m->m_pkthdr.len % 4 != 0) {
                ipseclog((LOG_ERR, "IPv6 ESP input: packet alignment problem "
                        "(off=%d, pktlen=%d)\n", off, m->m_pkthdr.len));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, ESPMAXLEN, {return IPPROTO_DONE;});
        esp = (struct esp *)(void *)(mtod(m, caddr_t) + off);
#else
        IP6_EXTHDR_GET(esp, struct esp *, m, off, ESPMAXLEN);
        if (esp == NULL) {
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                return IPPROTO_DONE;
        }
#endif
        /* Expect 32-bit data aligned pointer on strict-align platforms */
        MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);

        ip6 = mtod(m, struct ip6_hdr *);

        if (ntohs(ip6->ip6_plen) == 0) {
                ipseclog((LOG_ERR, "IPv6 ESP input: "
                    "ESP with IPv6 jumbogram is not supported.\n"));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

        /* find the sassoc. */
        spi = esp->esp_spi;

        if ((sav = key_allocsa(AF_INET6,
                              (caddr_t)&ip6->ip6_src, (caddr_t)&ip6->ip6_dst,
                              IPPROTO_ESP, spi)) == 0) {
                ipseclog((LOG_WARNING,
                    "IPv6 ESP input: no key association found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_nosa);
                goto bad;
        }
        KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
            printf("DP esp6_input called to allocate SA:0x%llx\n",
            (uint64_t)VM_KERNEL_ADDRPERM(sav)));
        if (sav->state != SADB_SASTATE_MATURE
         && sav->state != SADB_SASTATE_DYING) {
                ipseclog((LOG_DEBUG,
                    "IPv6 ESP input: non-mature/dying SA found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_badspi);
                goto bad;
        }
        algo = esp_algorithm_lookup(sav->alg_enc);
        if (!algo) {
                ipseclog((LOG_DEBUG, "IPv6 ESP input: "
                    "unsupported encryption algorithm for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_badspi);
                goto bad;
        }

        /* check if we have proper ivlen information */
        ivlen = sav->ivlen;
        if (ivlen < 0) {
                ipseclog((LOG_ERR, "inproper ivlen in IPv6 ESP input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_badspi);
                goto bad;
        }

        seq = ntohl(((struct newesp *)esp)->esp_seq);

        if (!((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay
         && (sav->alg_auth && sav->key_auth)))
                goto noreplaycheck;

        if (sav->alg_auth == SADB_X_AALG_NULL ||
            sav->alg_auth == SADB_AALG_NONE)
                goto noreplaycheck;

        /*
         * check for sequence number.
         */
        if (ipsec_chkreplay(seq, sav))
                ; /*okey*/
        else {
                IPSEC_STAT_INCREMENT(ipsec6stat.in_espreplay);
                ipseclog((LOG_WARNING,
                    "replay packet in IPv6 ESP input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                goto bad;
        }

        /* check ICV */
    {
        u_char sum0[AH_MAXSUMSIZE] __attribute__((aligned(4)));
        u_char sum[AH_MAXSUMSIZE] __attribute__((aligned(4)));
        const struct ah_algorithm *sumalgo;
        size_t siz;

        sumalgo = ah_algorithm_lookup(sav->alg_auth);
        if (!sumalgo)
                goto noreplaycheck;
        siz = (((*sumalgo->sumsiz)(sav) + 3) & ~(4 - 1));
        if (m->m_pkthdr.len < off + ESPMAXLEN + siz) {
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto bad;
        }
        if (AH_MAXSUMSIZE < siz) {
                ipseclog((LOG_DEBUG,
                    "internal error: AH_MAXSUMSIZE must be larger than %lu\n",
                    (u_int32_t)siz));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

        m_copydata(m, m->m_pkthdr.len - siz, siz, (caddr_t) &sum0[0]);

        if (esp_auth(m, off, m->m_pkthdr.len - off - siz, sav, sum)) {
                ipseclog((LOG_WARNING, "auth fail in IPv6 ESP input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_espauthfail);
                goto bad;
        }

        if (bcmp(sum0, sum, siz) != 0) {
                ipseclog((LOG_WARNING, "auth fail in IPv6 ESP input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_espauthfail);
                goto bad;
        }

        /* strip off the authentication data */
        m_adj(m, -siz);
        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - siz);

        m->m_flags |= M_AUTHIPDGM;
        IPSEC_STAT_INCREMENT(ipsec6stat.in_espauthsucc);
    }

        /*
         * update sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_updatereplay(seq, sav)) {
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_espreplay);
                        goto bad;
                }
        }

noreplaycheck:

        /* process main esp header. */
        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1827 */
                esplen = sizeof(struct esp);
        } else {
                /* RFC 2406 */
                if (sav->flags & SADB_X_EXT_DERIV)
                        esplen = sizeof(struct esp);
                else
                        esplen = sizeof(struct newesp);
        }

        if (m->m_pkthdr.len < off + esplen + ivlen + sizeof(esptail)) {
                ipseclog((LOG_WARNING,
                    "IPv6 ESP input: packet too short\n"));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, esplen + ivlen, return IPPROTO_DONE);  /*XXX*/
#else
        IP6_EXTHDR_GET(esp, struct esp *, m, off, esplen + ivlen);
        if (esp == NULL) {
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                m = NULL;
                goto bad;
        }
#endif
        ip6 = mtod(m, struct ip6_hdr *);        /*set it again just in case*/

        /*
         * pre-compute and cache intermediate key
         */
        if (esp_schedule(algo, sav) != 0) {
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

        /*
         * decrypt the packet.
         */
        if (!algo->decrypt)
                panic("internal error: no decrypt function");
        if ((*algo->decrypt)(m, off, sav, algo, ivlen)) {
                /* m is already freed */
                m = NULL;
                ipseclog((LOG_ERR, "decrypt fail in IPv6 ESP input: %s\n",
                    ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }
        IPSEC_STAT_INCREMENT(ipsec6stat.in_esphist[sav->alg_enc]);

        m->m_flags |= M_DECRYPTED;

        /*
         * find the trailer of the ESP.
         */
        m_copydata(m, m->m_pkthdr.len - sizeof(esptail), sizeof(esptail),
             (caddr_t)&esptail);
        nxt = esptail.esp_nxt;
        taillen = esptail.esp_padlen + sizeof(esptail);

        if (m->m_pkthdr.len < taillen
         || m->m_pkthdr.len - taillen < sizeof(struct ip6_hdr)) {       /*?*/
                ipseclog((LOG_WARNING,
                    "bad pad length in IPv6 ESP input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto bad;
        }

        /* strip off the trailing pad area. */
        m_adj(m, -taillen);
        ip6 = mtod(m, struct ip6_hdr *);
        ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - taillen);

        if (sav->utun_is_keepalive_fn) {
                if (sav->utun_is_keepalive_fn(sav->utun_pcb, &m, nxt, sav->flags, (off + esplen + ivlen))) {
                        if (m) {
                                // not really bad, we just wanna exit
                                IPSEC_STAT_INCREMENT(ipsec6stat.in_success);
                                m = NULL;
                        }
                        goto bad;
                }
        }

        /* was it transmitted over the IPsec tunnel SA? */
        if (ipsec6_tunnel_validate(m, off + esplen + ivlen, nxt, sav)) {
                ifaddr_t ifa;
                struct sockaddr_storage addr;

                /*
                 * strip off all the headers that precedes ESP header.
                 *      IP6 xx ESP IP6' payload -> IP6' payload
                 *
                 * XXX more sanity checks
                 * XXX relationship with gif?
                 */
                u_int32_t flowinfo;     /*net endian*/
                flowinfo = ip6->ip6_flow;
                m_adj(m, off + esplen + ivlen);
                if (m->m_len < sizeof(*ip6)) {
#ifndef PULLDOWN_TEST
                        /*
                         * m_pullup is prohibited in KAME IPv6 input processing
                         * but there's no other way!
                         */
#else
                        /* okay to pullup in m_pulldown style */
#endif
                        m = m_pullup(m, sizeof(*ip6));
                        if (!m) {
                                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                                goto bad;
                        }
                }
                ip6 = mtod(m, struct ip6_hdr *);
                /* ECN consideration. */
                ip6_ecn_egress(ip6_ipsec_ecn, &flowinfo, &ip6->ip6_flow);
                if (!key_checktunnelsanity(sav, AF_INET6,
                            (caddr_t)&ip6->ip6_src, (caddr_t)&ip6->ip6_dst)) {
                        ipseclog((LOG_ERR, "ipsec tunnel address mismatch "
                            "in IPv6 ESP input: %s %s\n",
                            ipsec6_logpacketstr(ip6, spi),
                            ipsec_logsastr(sav)));
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                        goto bad;
                }

                key_sa_recordxfer(sav, m);
                if (ipsec_addhist(m, IPPROTO_ESP, spi) != 0 || 
                    ipsec_addhist(m, IPPROTO_IPV6, 0) != 0) {
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_nomem);
                        goto bad;
                }

                if (ip6_doscopedroute) {
                        struct sockaddr_in6 *ip6addr;

                        bzero(&addr, sizeof(addr));
                        ip6addr = (__typeof__(ip6addr))&addr;
                        ip6addr->sin6_family = AF_INET6;
                        ip6addr->sin6_len = sizeof(*ip6addr);
                        ip6addr->sin6_addr = ip6->ip6_dst;

                        // update the receiving interface address based on the inner address
                        ifa = ifa_ifwithaddr((struct sockaddr *)&addr);
                        if (ifa) {
                                m->m_pkthdr.rcvif = ifa->ifa_ifp;
                                IFA_REMREF(ifa);
                        }
                }

                if (sav->utun_in_fn) {
                        if (!(sav->utun_in_fn(sav->utun_pcb, &m, PF_INET6))) {
                                m = NULL;
                                // we just wanna exit since packet has been completely processed
                                goto bad;
                        }
                }

                if (proto_input(PF_INET6, m) != 0)
                        goto bad;
                nxt = IPPROTO_DONE;
        } else {
                /*
                 * strip off ESP header and IV.
                 * even in m_pulldown case, we need to strip off ESP so that
                 * we can always compute checksum for AH correctly.
                 */
                size_t stripsiz;
                char *prvnxtp;

                /*
                 * Set the next header field of the previous header correctly.
                 */
                prvnxtp = ip6_get_prevhdr(m, off); /* XXX */
                *prvnxtp = nxt;

                stripsiz = esplen + ivlen;

                ip6 = mtod(m, struct ip6_hdr *);
                if (m->m_len >= stripsiz + off) {
                        ovbcopy((caddr_t)ip6, ((caddr_t)ip6) + stripsiz, off);
                        m->m_data += stripsiz;
                        m->m_len -= stripsiz;
                        m->m_pkthdr.len -= stripsiz;
                } else {
                        /*
                         * this comes with no copy if the boundary is on
                         * cluster
                         */
                        struct mbuf *n;

                        n = m_split(m, off, M_DONTWAIT);
                        if (n == NULL) {
                                /* m is retained by m_split */
                                goto bad;
                        }
                        m_adj(n, stripsiz);
                        /* m_cat does not update m_pkthdr.len */
                        m->m_pkthdr.len += n->m_pkthdr.len;
                        m_cat(m, n);
                }

#ifndef PULLDOWN_TEST
                /*
                 * KAME requires that the packet to be contiguous on the
                 * mbuf.  We need to make that sure.
                 * this kind of code should be avoided.
                 * XXX other conditions to avoid running this part?
                 */
                if (m->m_len != m->m_pkthdr.len) {
                        struct mbuf *n = NULL;
                        int maxlen;

                        MGETHDR(n, M_DONTWAIT, MT_HEADER);      /* MAC-OK */
                        maxlen = MHLEN;
                        if (n)
                                M_COPY_PKTHDR(n, m);
                        if (n && m->m_pkthdr.len > maxlen) {
                                MCLGET(n, M_DONTWAIT);
                                maxlen = MCLBYTES;
                                if ((n->m_flags & M_EXT) == 0) {
                                        m_free(n);
                                        n = NULL;
                                }
                        }
                        if (!n) {
                                printf("esp6_input: mbuf allocation failed\n");
                                goto bad;
                        }

                        if (m->m_pkthdr.len <= maxlen) {
                                m_copydata(m, 0, m->m_pkthdr.len, mtod(n, caddr_t));
                                n->m_len = m->m_pkthdr.len;
                                n->m_pkthdr.len = m->m_pkthdr.len;
                                n->m_next = NULL;
                                m_freem(m);
                        } else {
                                m_copydata(m, 0, maxlen, mtod(n, caddr_t));
                                n->m_len = maxlen;
                                n->m_pkthdr.len = m->m_pkthdr.len;
                                n->m_next = m;
                                m_adj(m, maxlen);
                                m->m_flags &= ~M_PKTHDR;
                        }
                        m = n;
                }
#endif

                ip6 = mtod(m, struct ip6_hdr *);
                ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - stripsiz);

                key_sa_recordxfer(sav, m);
                if (ipsec_addhist(m, IPPROTO_ESP, spi) != 0) {
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_nomem);
                        goto bad;
                }

                if (sav->utun_in_fn) {
                        if (!(sav->utun_in_fn(sav->utun_pcb, &m, PF_INET6))) {
                                m = NULL;
                                // we just wanna exit since packet has been completely processed
                                goto bad;
                        }
                }
        }

        *offp = off;
        *mp = m;

        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                    printf("DP esp6_input call free SA:0x%llx\n",
                    (uint64_t)VM_KERNEL_ADDRPERM(sav)));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        IPSEC_STAT_INCREMENT(ipsec6stat.in_success);
        return nxt;

bad:
        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                    printf("DP esp6_input call free SA:0x%llx\n",
                    (uint64_t)VM_KERNEL_ADDRPERM(sav)));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        if (m)
                m_freem(m);
        return IPPROTO_DONE;
}

void
esp6_ctlinput(cmd, sa, d)
        int cmd;
        struct sockaddr *sa;
        void *d;
{
        const struct newesp *espp;
        struct newesp esp;
        struct ip6ctlparam *ip6cp = NULL, ip6cp1;
        struct secasvar *sav;
        struct ip6_hdr *ip6;
        struct mbuf *m;
        int off;
        struct sockaddr_in6 *sa6_src, *sa6_dst;

        if (sa->sa_family != AF_INET6 ||
            sa->sa_len != sizeof(struct sockaddr_in6))
                return;
        if ((unsigned)cmd >= PRC_NCMDS)
                return;

        /* if the parameter is from icmp6, decode it. */
        if (d != NULL) {
                ip6cp = (struct ip6ctlparam *)d;
                m = ip6cp->ip6c_m;
                ip6 = ip6cp->ip6c_ip6;
                off = ip6cp->ip6c_off;
        } else {
                m = NULL;
                ip6 = NULL;
        }

        if (ip6) {
                /*
                 * Notify the error to all possible sockets via pfctlinput2.
                 * Since the upper layer information (such as protocol type,
                 * source and destination ports) is embedded in the encrypted
                 * data and might have been cut, we can't directly call
                 * an upper layer ctlinput function. However, the pcbnotify
                 * function will consider source and destination addresses
                 * as well as the flow info value, and may be able to find
                 * some PCB that should be notified.
                 * Although pfctlinput2 will call esp6_ctlinput(), there is
                 * no possibility of an infinite loop of function calls,
                 * because we don't pass the inner IPv6 header.
                 */
                bzero(&ip6cp1, sizeof(ip6cp1));
                ip6cp1.ip6c_src = ip6cp->ip6c_src;
                pfctlinput2(cmd, sa, (void *)&ip6cp1);

                /*
                 * Then go to special cases that need ESP header information.
                 * XXX: We assume that when ip6 is non NULL,
                 * M and OFF are valid.
                 */

                /* check if we can safely examine src and dst ports */
                if (m->m_pkthdr.len < off + sizeof(esp))
                        return;

                if (m->m_len < off + sizeof(esp)) {
                        /*
                         * this should be rare case,
                         * so we compromise on this copy...
                         */
                        m_copydata(m, off, sizeof(esp), (caddr_t)&esp);
                        espp = &esp;
                } else
                        espp = (struct newesp*)(void *)(mtod(m, caddr_t) + off);

                if (cmd == PRC_MSGSIZE) {
                        int valid = 0;

                        /*
                         * Check to see if we have a valid SA corresponding to
                         * the address in the ICMP message payload.
                         */
                        sa6_src = ip6cp->ip6c_src;
                        sa6_dst = (struct sockaddr_in6 *)(void *)sa;
                        sav = key_allocsa(AF_INET6,
                                          (caddr_t)&sa6_src->sin6_addr,
                                          (caddr_t)&sa6_dst->sin6_addr,
                                          IPPROTO_ESP, espp->esp_spi);
                        if (sav) {
                                if (sav->state == SADB_SASTATE_MATURE ||
                                    sav->state == SADB_SASTATE_DYING)
                                        valid++;
                                key_freesav(sav, KEY_SADB_LOCKED);
                        }

                        /* XXX Further validation? */

                        /*
                         * Depending on the value of "valid" and routing table
                         * size (mtudisc_{hi,lo}wat), we will:
                         * - recalcurate the new MTU and create the
                         *   corresponding routing entry, or
                         * - ignore the MTU change notification.
                         */
                        icmp6_mtudisc_update((struct ip6ctlparam *)d, valid);
                }
        } else {
                /* we normally notify any pcb here */
        }
}
#endif /* INET6 */