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

/*
 * Copyright (c) 2008 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/ah_input.c,v 1.1.2.6 2002/04/28 05:40:26 suz Exp $   */
/*      $KAME: ah_input.c,v 1.67 2002/01/07 11:39:56 kjc 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.
 */

/*
 * RFC1826/2402 authentication header.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.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/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_ecn.h>
#include <netinet/in_pcb.h>
#if INET6
#include <netinet6/ip6_ecn.h>
#endif

#if INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.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 <netkey/key.h>
#include <netkey/keydb.h>
#if IPSEC_DEBUG
#include <netkey/key_debug.h>
#else
#define KEYDEBUG(lev,arg)
#endif

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

#include <net/net_osdep.h>

#define IPLEN_FLIPPED

#if INET
extern struct protosw inetsw[];

void
ah4_input(struct mbuf *m, int off)
{
        struct ip *ip;
        struct ah *ah;
        u_int32_t spi;
        const struct ah_algorithm *algo;
        size_t siz;
        size_t siz1;
        u_char *cksum;
        struct secasvar *sav = NULL;
        u_int16_t nxt;
        size_t hlen;
        size_t stripsiz = 0;
        sa_family_t ifamily;

#ifndef PULLDOWN_TEST
        if (m->m_len < off + sizeof(struct newah)) {
                m = m_pullup(m, off + sizeof(struct newah));
                if (!m) {
                        ipseclog((LOG_DEBUG, "IPv4 AH input: can't pullup;"
                                "dropping the packet for simplicity\n"));
                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                        goto fail;
                }
        }

        ip = mtod(m, struct ip *);
        ah = (struct ah *)(((caddr_t)ip) + off);
#else
        ip = mtod(m, struct ip *);
        IP6_EXTHDR_GET(ah, struct ah *, m, off, sizeof(struct newah));
        if (ah == NULL) {
                ipseclog((LOG_DEBUG, "IPv4 AH input: can't pullup;"
                        "dropping the packet for simplicity\n"));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }
#endif
        nxt = ah->ah_nxt;
#ifdef _IP_VHL
        hlen = IP_VHL_HL(ip->ip_vhl) << 2;
#else
        hlen = ip->ip_hl << 2;
#endif

        /* find the sassoc. */
        spi = ah->ah_spi;

        if ((sav = key_allocsa(AF_INET,
                              (caddr_t)&ip->ip_src, (caddr_t)&ip->ip_dst,
                              IPPROTO_AH, spi)) == 0) {
                ipseclog((LOG_WARNING,
                    "IPv4 AH input: no key association found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_nosa);
                goto fail;
        }
        KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                printf("DP ah4_input called to allocate SA:%p\n", sav));
        if (sav->state != SADB_SASTATE_MATURE
         && sav->state != SADB_SASTATE_DYING) {
                ipseclog((LOG_DEBUG,
                    "IPv4 AH input: non-mature/dying SA found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_badspi);
                goto fail;
        }

        algo = ah_algorithm_lookup(sav->alg_auth);
        if (!algo) {
                ipseclog((LOG_DEBUG, "IPv4 AH input: "
                    "unsupported authentication algorithm for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_badspi);
                goto fail;
        }

        siz = (*algo->sumsiz)(sav);
        siz1 = ((siz + 3) & ~(4 - 1));

        /*
         * sanity checks for header, 1.
         */
    {
        int sizoff;

        sizoff = (sav->flags & SADB_X_EXT_OLD) ? 0 : 4;

        /*
         * Here, we do not do "siz1 == siz".  This is because the way
         * RFC240[34] section 2 is written.  They do not require truncation
         * to 96 bits.
         * For example, Microsoft IPsec stack attaches 160 bits of
         * authentication data for both hmac-md5 and hmac-sha1.  For hmac-sha1,
         * 32 bits of padding is attached.
         *
         * There are two downsides to this specification.
         * They have no real harm, however, they leave us fuzzy feeling.
         * - if we attach more than 96 bits of authentication data onto AH,
         *   we will never notice about possible modification by rogue
         *   intermediate nodes.
         *   Since extra bits in AH checksum is never used, this constitutes
         *   no real issue, however, it is wacky.
         * - even if the peer attaches big authentication data, we will never
         *   notice the difference, since longer authentication data will just
         *   work.
         *
         * We may need some clarification in the spec.
         */
        if (siz1 < siz) {
                ipseclog((LOG_NOTICE, "sum length too short in IPv4 AH input "
                    "(%lu, should be at least %lu): %s\n",
                    (u_int32_t)siz1, (u_int32_t)siz,
                    ipsec4_logpacketstr(ip, spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }
        if ((ah->ah_len << 2) - sizoff != siz1) {
                ipseclog((LOG_NOTICE, "sum length mismatch in IPv4 AH input "
                    "(%d should be %lu): %s\n",
                    (ah->ah_len << 2) - sizoff, (u_int32_t)siz1,
                    ipsec4_logpacketstr(ip, spi)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }

#ifndef PULLDOWN_TEST
        if (m->m_len < off + sizeof(struct ah) + sizoff + siz1) {
                m = m_pullup(m, off + sizeof(struct ah) + sizoff + siz1);
                if (!m) {
                        ipseclog((LOG_DEBUG, "IPv4 AH input: can't pullup\n"));
                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                        goto fail;
                }

                ip = mtod(m, struct ip *);
                ah = (struct ah *)(((caddr_t)ip) + off);
        }
#else
        IP6_EXTHDR_GET(ah, struct ah *, m, off,
                sizeof(struct ah) + sizoff + siz1);
        if (ah == NULL) {
                ipseclog((LOG_DEBUG, "IPv4 AH input: can't pullup\n"));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }
#endif
    }

        /*
         * check for sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_chkreplay(ntohl(((struct newah *)ah)->ah_seq), sav))
                        ; /*okey*/
                else {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_ahreplay);
                        ipseclog((LOG_WARNING,
                            "replay packet in IPv4 AH input: %s %s\n",
                            ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                        goto fail;
                }
        }

        /*
         * alright, it seems sane.  now we are going to check the
         * cryptographic checksum.
         */
        cksum = _MALLOC(siz1, M_TEMP, M_NOWAIT);
        if (!cksum) {
                ipseclog((LOG_DEBUG, "IPv4 AH input: "
                    "couldn't alloc temporary region for cksum\n"));
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }
        
        /*
         * some of IP header fields are flipped to the host endian.
         * convert them back to network endian.  VERY stupid.
         */
        ip->ip_len = htons(ip->ip_len + hlen);
        ip->ip_off = htons(ip->ip_off);
        if (ah4_calccksum(m, (caddr_t)cksum, siz1, algo, sav)) {
                FREE(cksum, M_TEMP);
                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                goto fail;
        }
        IPSEC_STAT_INCREMENT(ipsecstat.in_ahhist[sav->alg_auth]);
        /*
         * flip them back.
         */
        ip->ip_len = ntohs(ip->ip_len) - hlen;
        ip->ip_off = ntohs(ip->ip_off);

    {
        caddr_t sumpos = NULL;

        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1826 */
                sumpos = (caddr_t)(ah + 1);
        } else {
                /* RFC 2402 */
                sumpos = (caddr_t)(((struct newah *)ah) + 1);
        }

        if (bcmp(sumpos, cksum, siz) != 0) {
                ipseclog((LOG_WARNING,
                    "checksum mismatch in IPv4 AH input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                FREE(cksum, M_TEMP);
                IPSEC_STAT_INCREMENT(ipsecstat.in_ahauthfail);
                goto fail;
        }
    }

        FREE(cksum, M_TEMP);

        m->m_flags |= M_AUTHIPHDR;
        m->m_flags |= M_AUTHIPDGM;

#if 0
        /*
         * looks okey, but we need more sanity check.
         * XXX should elaborate.
         */
        if (ah->ah_nxt == IPPROTO_IPIP || ah->ah_nxt == IPPROTO_IP) {
                struct ip *nip;
                size_t sizoff;

                sizoff = (sav->flags & SADB_X_EXT_OLD) ? 0 : 4;

                if (m->m_len < off + sizeof(struct ah) + sizoff + siz1 + hlen) {
                        m = m_pullup(m, off + sizeof(struct ah)
                                        + sizoff + siz1 + hlen);
                        if (!m) {
                                ipseclog((LOG_DEBUG,
                                    "IPv4 AH input: can't pullup\n"));
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto fail;
                        }
                }

                nip = (struct ip *)((u_char *)(ah + 1) + sizoff + siz1);
                if (nip->ip_src.s_addr != ip->ip_src.s_addr
                 || nip->ip_dst.s_addr != ip->ip_dst.s_addr) {
                        m->m_flags &= ~M_AUTHIPHDR;
                        m->m_flags &= ~M_AUTHIPDGM;
                }
        }
#if INET6
        else if (ah->ah_nxt == IPPROTO_IPV6) {
                m->m_flags &= ~M_AUTHIPHDR;
                m->m_flags &= ~M_AUTHIPDGM;
        }
#endif /*INET6*/
#endif /*0*/

        if (m->m_flags & M_AUTHIPHDR
         && m->m_flags & M_AUTHIPDGM) {
#if 0
                ipseclog((LOG_DEBUG,
                    "IPv4 AH input: authentication succeess\n"));
#endif
                IPSEC_STAT_INCREMENT(ipsecstat.in_ahauthsucc);
        } else {
                ipseclog((LOG_WARNING,
                    "authentication failed in IPv4 AH input: %s %s\n",
                    ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsecstat.in_ahauthfail);
                goto fail;
        }

        /*
         * update sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_updatereplay(ntohl(((struct newah *)ah)->ah_seq), sav)) {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_ahreplay);
                        goto fail;
                }
        }

        /* was it transmitted over the IPsec tunnel SA? */
        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1826 */
                stripsiz = sizeof(struct ah) + siz1;
        } else {
                /* RFC 2402 */
                stripsiz = sizeof(struct newah) + siz1;
        }
        if (ipsec4_tunnel_validate(m, off + stripsiz, nxt, sav, &ifamily)) {
                ifaddr_t ifa;
                struct sockaddr_storage addr;

                /*
                 * strip off all the headers that precedes AH.
                 *      IP xx AH IP' payload -> IP' payload
                 *
                 * XXX more sanity checks
                 * XXX relationship with gif?
                 */
                u_int8_t tos;
                
                if (ifamily == AF_INET6) {
                        ipseclog((LOG_NOTICE, "ipsec tunnel protocol mismatch "
                            "in IPv4 AH input: %s\n", ipsec_logsastr(sav)));
                        goto fail;
                }
                tos = ip->ip_tos;
                m_adj(m, off + stripsiz);
                if (m->m_len < sizeof(*ip)) {
                        m = m_pullup(m, sizeof(*ip));
                        if (!m) {
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto fail;
                        }
                }
                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_NOTICE, "ipsec tunnel address mismatch "
                            "in IPv4 AH input: %s %s\n",
                            ipsec4_logpacketstr(ip, spi), ipsec_logsastr(sav)));
                        IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                        goto fail;
                }

#if 1
                /*
                 * Should the inner packet be considered authentic?
                 * My current answer is: NO.
                 *
                 * host1 -- gw1 === gw2 -- host2
                 *      In this case, gw2 can trust the authenticity of the
                 *      outer packet, but NOT inner.  Packet may be altered
                 *      between host1 and gw1.
                 *
                 * host1 -- gw1 === host2
                 *      This case falls into the same scenario as above.
                 *
                 * host1 === host2
                 *      This case is the only case when we may be able to leave
                 *      M_AUTHIPHDR and M_AUTHIPDGM set.
                 *      However, if host1 is wrongly configured, and allows
                 *      attacker to inject some packet with src=host1 and
                 *      dst=host2, you are in risk.
                 */
                m->m_flags &= ~M_AUTHIPHDR;
                m->m_flags &= ~M_AUTHIPDGM;
#endif

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

                if (ip_doscopedroute) {
                        struct sockaddr_in *ipaddr;

                        bzero(&addr, sizeof(addr));
                        ipaddr = (__typeof__(ipaddr))&addr;
                        ipaddr->sin_family = AF_INET;
                        ipaddr->sin_len = sizeof(*ipaddr);
                        ipaddr->sin_addr = ip->ip_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 (proto_input(PF_INET, m) != 0)
                        goto fail;
                nxt = IPPROTO_DONE;
        } else {
                /*
                 * strip off AH.
                 */

                ip = mtod(m, struct ip *);
#ifndef PULLDOWN_TEST
                /*
                 * We do deep-copy since KAME requires that
                 * the packet is placed in a single external mbuf.
                 */
                ovbcopy((caddr_t)ip, (caddr_t)(((u_char *)ip) + stripsiz), off);
                m->m_data += stripsiz;
                m->m_len -= stripsiz;
                m->m_pkthdr.len -= stripsiz;
#else
                /*
                 * even in m_pulldown case, we need to strip off AH so that
                 * we can compute checksum for multiple AH correctly.
                 */
                if (m->m_len >= stripsiz + off) {
                        ovbcopy((caddr_t)ip, ((caddr_t)ip) + 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 fail;
                        }
                        m_adj(n, stripsiz);
                        /* m_cat does not update m_pkthdr.len */
                        m->m_pkthdr.len += n->m_pkthdr.len;
                        m_cat(m, n);
                }
#endif

                if (m->m_len < sizeof(*ip)) {
                        m = m_pullup(m, sizeof(*ip));
                        if (m == NULL) {
                                IPSEC_STAT_INCREMENT(ipsecstat.in_inval);
                                goto fail;
                        }
                }
                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;
                /* forget about IP hdr checksum, the check has already been passed */

                key_sa_recordxfer(sav, m);
                if (ipsec_addhist(m, IPPROTO_AH, spi) != 0) {
                        IPSEC_STAT_INCREMENT(ipsecstat.in_nomem);
                        goto fail;
                }

                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 (nxt != IPPROTO_DONE) {
                        if ((ip_protox[nxt]->pr_flags & PR_LASTHDR) != 0 &&
                            ipsec4_in_reject(m, NULL)) {
                                IPSEC_STAT_INCREMENT(ipsecstat.in_polvio);
                                goto fail;
                        }
                        ip_proto_dispatch_in(m, off, nxt, 0);
                } else
                        m_freem(m);
                m = NULL;
        }

        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                        printf("DP ah4_input call free SA:%p\n", sav));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        IPSEC_STAT_INCREMENT(ipsecstat.in_success);
        return;

fail:
        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                        printf("DP ah4_input call free SA:%p\n", sav));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        if (m)
                m_freem(m);
        return;
}
#endif /* INET */

#if INET6
int
ah6_input(struct mbuf **mp, int *offp, int proto)
{
#pragma unused(proto)
        struct mbuf *m = *mp;
        int off = *offp;
        struct ip6_hdr *ip6;
        struct ah *ah;
        u_int32_t spi;
        const struct ah_algorithm *algo;
        size_t siz;
        size_t siz1;
        u_char *cksum;
        struct secasvar *sav = NULL;
        u_int16_t nxt;
        size_t stripsiz = 0;


#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, sizeof(struct ah), {return IPPROTO_DONE;});
        ah = (struct ah *)(mtod(m, caddr_t) + off);
#else
        IP6_EXTHDR_GET(ah, struct ah *, m, off, sizeof(struct newah));
        if (ah == NULL) {
                ipseclog((LOG_DEBUG, "IPv6 AH input: can't pullup\n"));
                ipsec6stat.in_inval++;
                return IPPROTO_DONE;
        }
#endif
        ip6 = mtod(m, struct ip6_hdr *);
        nxt = ah->ah_nxt;

        /* find the sassoc.  */
        spi = ah->ah_spi;

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

        if ((sav = key_allocsa(AF_INET6,
                              (caddr_t)&ip6->ip6_src, (caddr_t)&ip6->ip6_dst,
                              IPPROTO_AH, spi)) == 0) {
                ipseclog((LOG_WARNING,
                    "IPv6 AH input: no key association found for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_nosa);
                goto fail;
        }
        KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                printf("DP ah6_input called to allocate SA:%p\n", sav));
        if (sav->state != SADB_SASTATE_MATURE
         && sav->state != SADB_SASTATE_DYING) {
                ipseclog((LOG_DEBUG,
                    "IPv6 AH input: non-mature/dying SA found for spi %u; ",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_badspi);
                goto fail;
        }

        algo = ah_algorithm_lookup(sav->alg_auth);
        if (!algo) {
                ipseclog((LOG_DEBUG, "IPv6 AH input: "
                    "unsupported authentication algorithm for spi %u\n",
                    (u_int32_t)ntohl(spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_badspi);
                goto fail;
        }

        siz = (*algo->sumsiz)(sav);
        siz1 = ((siz + 3) & ~(4 - 1));

        /*
         * sanity checks for header, 1.
         */
    {
        int sizoff;

        sizoff = (sav->flags & SADB_X_EXT_OLD) ? 0 : 4;

        /*
         * Here, we do not do "siz1 == siz".  See ah4_input() for complete
         * description.
         */
        if (siz1 < siz) {
                ipseclog((LOG_NOTICE, "sum length too short in IPv6 AH input "
                    "(%lu, should be at least %lu): %s\n",
                    (u_int32_t)siz1, (u_int32_t)siz,
                    ipsec6_logpacketstr(ip6, spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto fail;
        }
        if ((ah->ah_len << 2) - sizoff != siz1) {
                ipseclog((LOG_NOTICE, "sum length mismatch in IPv6 AH input "
                    "(%d should be %lu): %s\n",
                    (ah->ah_len << 2) - sizoff, (u_int32_t)siz1,
                    ipsec6_logpacketstr(ip6, spi)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto fail;
        }
#ifndef PULLDOWN_TEST
        IP6_EXTHDR_CHECK(m, off, sizeof(struct ah) + sizoff + siz1, 
                {return IPPROTO_DONE;});
#else
        IP6_EXTHDR_GET(ah, struct ah *, m, off,
                sizeof(struct ah) + sizoff + siz1);
        if (ah == NULL) {
                ipseclog((LOG_NOTICE, "couldn't pullup gather IPv6 AH checksum part"));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                m = NULL;
                goto fail;
        }
#endif
    }

        /*
         * check for sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_chkreplay(ntohl(((struct newah *)ah)->ah_seq), sav))
                        ; /*okey*/
                else {
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_ahreplay);
                        ipseclog((LOG_WARNING,
                            "replay packet in IPv6 AH input: %s %s\n",
                            ipsec6_logpacketstr(ip6, spi),
                            ipsec_logsastr(sav)));
                        goto fail;
                }
        }

        /*
         * alright, it seems sane.  now we are going to check the
         * cryptographic checksum.
         */
        cksum = _MALLOC(siz1, M_TEMP, M_NOWAIT);
        if (!cksum) {
                ipseclog((LOG_DEBUG, "IPv6 AH input: "
                    "couldn't alloc temporary region for cksum\n"));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto fail;
        }
        
        if (ah6_calccksum(m, (caddr_t)cksum, siz1, algo, sav)) {
                FREE(cksum, M_TEMP);
                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                goto fail;
        }
        IPSEC_STAT_INCREMENT(ipsec6stat.in_ahhist[sav->alg_auth]);

    {
        caddr_t sumpos = NULL;

        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1826 */
                sumpos = (caddr_t)(ah + 1);
        } else {
                /* RFC 2402 */
                sumpos = (caddr_t)(((struct newah *)ah) + 1);
        }

        if (bcmp(sumpos, cksum, siz) != 0) {
                ipseclog((LOG_WARNING,
                    "checksum mismatch in IPv6 AH input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                FREE(cksum, M_TEMP);
                IPSEC_STAT_INCREMENT(ipsec6stat.in_ahauthfail);
                goto fail;
        }
    }

        FREE(cksum, M_TEMP);

        m->m_flags |= M_AUTHIPHDR;
        m->m_flags |= M_AUTHIPDGM;

#if 0
        /*
         * looks okey, but we need more sanity check.
         * XXX should elaborate.
         */
        if (ah->ah_nxt == IPPROTO_IPV6) {
                struct ip6_hdr *nip6;
                size_t sizoff;

                sizoff = (sav->flags & SADB_X_EXT_OLD) ? 0 : 4;

                IP6_EXTHDR_CHECK(m, off, sizeof(struct ah) + sizoff + siz1
                                + sizeof(struct ip6_hdr), 
                                {return IPPROTO_DONE;});

                nip6 = (struct ip6_hdr *)((u_char *)(ah + 1) + sizoff + siz1);
                if (!IN6_ARE_ADDR_EQUAL(&nip6->ip6_src, &ip6->ip6_src)
                 || !IN6_ARE_ADDR_EQUAL(&nip6->ip6_dst, &ip6->ip6_dst)) {
                        m->m_flags &= ~M_AUTHIPHDR;
                        m->m_flags &= ~M_AUTHIPDGM;
                }
        } else if (ah->ah_nxt == IPPROTO_IPIP) {
                m->m_flags &= ~M_AUTHIPHDR;
                m->m_flags &= ~M_AUTHIPDGM;
        } else if (ah->ah_nxt == IPPROTO_IP) {
                m->m_flags &= ~M_AUTHIPHDR;
                m->m_flags &= ~M_AUTHIPDGM;
        }
#endif

        if (m->m_flags & M_AUTHIPHDR
         && m->m_flags & M_AUTHIPDGM) {
#if 0
                ipseclog((LOG_DEBUG,
                    "IPv6 AH input: authentication succeess\n"));
#endif
                IPSEC_STAT_INCREMENT(ipsec6stat.in_ahauthsucc);
        } else {
                ipseclog((LOG_WARNING,
                    "authentication failed in IPv6 AH input: %s %s\n",
                    ipsec6_logpacketstr(ip6, spi), ipsec_logsastr(sav)));
                IPSEC_STAT_INCREMENT(ipsec6stat.in_ahauthfail);
                goto fail;
        }

        /*
         * update sequence number.
         */
        if ((sav->flags & SADB_X_EXT_OLD) == 0 && sav->replay) {
                if (ipsec_updatereplay(ntohl(((struct newah *)ah)->ah_seq), sav)) {
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_ahreplay);
                        goto fail;
                }
        }

        /* was it transmitted over the IPsec tunnel SA? */
        if (sav->flags & SADB_X_EXT_OLD) {
                /* RFC 1826 */
                stripsiz = sizeof(struct ah) + siz1;
        } else {
                /* RFC 2402 */
                stripsiz = sizeof(struct newah) + siz1;
        }
        if (ipsec6_tunnel_validate(m, off + stripsiz, nxt, sav)) {
                ifaddr_t ifa;
                struct sockaddr_storage addr;

                /*
                 * strip off all the headers that precedes AH.
                 *      IP6 xx AH 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 + stripsiz);
                if (m->m_len < sizeof(*ip6)) {
                        /*
                         * m_pullup is prohibited in KAME IPv6 input processing
                         * but there's no other way!
                         */
                        m = m_pullup(m, sizeof(*ip6));
                        if (!m) {
                                IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                                goto fail;
                        }
                }
                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_NOTICE, "ipsec tunnel address mismatch "
                            "in IPv6 AH input: %s %s\n",
                            ipsec6_logpacketstr(ip6, spi),
                            ipsec_logsastr(sav)));
                        IPSEC_STAT_INCREMENT(ipsec6stat.in_inval);
                        goto fail;
                }

#if 1
                /*
                 * should the inner packet be considered authentic?
                 * see comment in ah4_input().
                 */
                m->m_flags &= ~M_AUTHIPHDR;
                m->m_flags &= ~M_AUTHIPDGM;
#endif

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

                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 (proto_input(PF_INET6, m) != 0)
                        goto fail;
                nxt = IPPROTO_DONE;
        } else {
                /*
                 * strip off AH.
                 */
                char *prvnxtp;

                /*
                 * Copy the value of the next header field of AH to the
                 * next header field of the previous header.
                 * This is necessary because AH will be stripped off below.
                 */
                prvnxtp = ip6_get_prevhdr(m, off); /* XXX */
                *prvnxtp = nxt;

                ip6 = mtod(m, struct ip6_hdr *);
#ifndef PULLDOWN_TEST
                /*
                 * We do deep-copy since KAME requires that
                 * the packet is placed in a single mbuf.
                 */
                ovbcopy((caddr_t)ip6, ((caddr_t)ip6) + stripsiz, off);
                m->m_data += stripsiz;
                m->m_len -= stripsiz;
                m->m_pkthdr.len -= stripsiz;
#else
                /*
                 * even in m_pulldown case, we need to strip off AH so that
                 * we can compute checksum for multiple AH correctly.
                 */
                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 fail;
                        }
                        m_adj(n, stripsiz);
                        /* m_cat does not update m_pkthdr.len */
                        m->m_pkthdr.len += n->m_pkthdr.len;
                        m_cat(m, n);
                }
#endif
                ip6 = mtod(m, struct ip6_hdr *);
                /* XXX jumbogram */
                ip6->ip6_plen = htons(ntohs(ip6->ip6_plen) - stripsiz);

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

        *offp = off;
        *mp = m;

        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                        printf("DP ah6_input call free SA:%p\n", sav));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        IPSEC_STAT_INCREMENT(ipsec6stat.in_success);
        return nxt;

fail:
        if (sav) {
                KEYDEBUG(KEYDEBUG_IPSEC_STAMP,
                        printf("DP ah6_input call free SA:%p\n", sav));
                key_freesav(sav, KEY_SADB_UNLOCKED);
        }
        if (m)
                m_freem(m);
        return IPPROTO_DONE;
}

void
ah6_ctlinput(cmd, sa, d)
        int cmd;
        struct sockaddr *sa;
        void *d;
{
        const struct newah *ahp;
        struct newah ah;
        struct secasvar *sav;
        struct ip6_hdr *ip6;
        struct mbuf *m;
        struct ip6ctlparam *ip6cp = NULL;
        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) {
                /*
                 * 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(ah))
                        return;

                if (m->m_len < off + sizeof(ah)) {
                        /*
                         * this should be rare case,
                         * so we compromise on this copy...
                         */
                        m_copydata(m, off, sizeof(ah), (caddr_t)&ah);
                        ahp = &ah;
                } else
                        ahp = (struct newah *)(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 *)sa;
                        sav = key_allocsa(AF_INET6,
                                          (caddr_t)&sa6_src->sin6_addr,
                                          (caddr_t)&sa6_dst->sin6_addr,
                                          IPPROTO_AH, ahp->ah_spi);
                        if (sav) {
                                if (sav->state == SADB_SASTATE_MATURE ||
                                    sav->state == SADB_SASTATE_DYING)
                                        valid++;
                                key_freesav(sav, KEY_SADB_UNLOCKED);
                        }

                        /* 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);
                }

                /* we normally notify single pcb here */
        } else {
                /* we normally notify any pcb here */
        }
}
#endif /* INET6 */