/*      $NetBSD: xform_ah.c,v 1.115 2024/07/05 04:31:54 rin Exp $       */
/*      $FreeBSD: xform_ah.c,v 1.1.4.1 2003/01/24 05:11:36 sam Exp $    */
/*      $OpenBSD: ip_ah.c,v 1.63 2001/06/26 06:18:58 angelos Exp $ */
/*
 * The authors of this code are John Ioannidis (ji@tla.org),
 * Angelos D. Keromytis (kermit@csd.uch.gr) and
 * Niels Provos (provos@physnet.uni-hamburg.de).
 *
 * The original version of this code was written by John Ioannidis
 * for BSD/OS in Athens, Greece, in November 1995.
 *
 * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
 * by Angelos D. Keromytis.
 *
 * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
 * and Niels Provos.
 *
 * Additional features in 1999 by Angelos D. Keromytis and Niklas Hallqvist.
 *
 * Copyright (c) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
 * Angelos D. Keromytis and Niels Provos.
 * Copyright (c) 1999 Niklas Hallqvist.
 * Copyright (c) 2001 Angelos D. Keromytis.
 *
 * Permission to use, copy, and modify this software with or without fee
 * is hereby granted, provided that this entire notice is included in
 * all copies of any software which is or includes a copy or
 * modification of this software.
 * You may use this code under the GNU public license if you so wish. Please
 * contribute changes back to the authors under this freer than GPL license
 * so that we may further the use of strong encryption without limitations to
 * all.
 *
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
 * PURPOSE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: xform_ah.c,v 1.115 2024/07/05 04:31:54 rin Exp $");

#if defined(_KERNEL_OPT)
#include "opt_inet.h"
#include "opt_ipsec.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/pool.h>
#include <sys/pserialize.h>
#include <sys/kmem.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_ecn.h>
#include <netinet/ip_var.h>
#include <netinet/ip6.h>

#include <net/route.h>
#include <netipsec/ipsec.h>
#include <netipsec/ipsec_private.h>
#include <netipsec/ah.h>
#include <netipsec/ah_var.h>
#include <netipsec/xform.h>

#ifdef INET6
#include <netinet6/ip6_var.h>
#include <netinet6/scope6_var.h>
#include <netipsec/ipsec6.h>
#endif

#include <netipsec/key.h>
#include <netipsec/key_debug.h>

#include <opencrypto/cryptodev.h>

/*
 * Return header size in bytes.  The old protocol did not support
 * the replay counter; the new protocol always includes the counter.
 */
#define HDRSIZE(sav) \
        (((sav)->flags & SADB_X_EXT_OLD) ? \
                sizeof(struct ah) : sizeof(struct ah) + sizeof(uint32_t))
/*
 * Return authenticator size in bytes.  The old protocol is known
 * to use a fixed 16-byte authenticator.  The new algorithm gets
 * this size from the xform but is (currently) always 12.
 */
#define AUTHSIZE(sav) \
        ((sav->flags & SADB_X_EXT_OLD) ? 16 : (sav)->tdb_authalgxform->authsize)

percpu_t *ahstat_percpu;

int ah_enable = 1;                      /* control flow of packets with AH */
int ip4_ah_cleartos = 1;                /* clear ip_tos when doing AH calc */

static const char ipseczeroes[256];

int ah_max_authsize;                    /* max authsize over all algorithms */

static void ah_input_cb(struct cryptop *);
static void ah_output_cb(struct cryptop *);

const uint8_t ah_stats[256] = { SADB_AALG_STATS_INIT };

static pool_cache_t ah_tdb_crypto_pool_cache;
static size_t ah_pool_item_size;

/*
 * NB: this is public for use by the PF_KEY support.
 */
const struct auth_hash *
ah_algorithm_lookup(int alg)
{

        switch (alg) {
        case SADB_X_AALG_NULL:
                return &auth_hash_null;
        case SADB_AALG_MD5HMAC:
                return &auth_hash_hmac_md5_96;
        case SADB_AALG_SHA1HMAC:
                return &auth_hash_hmac_sha1_96;
        case SADB_X_AALG_RIPEMD160HMAC:
                return &auth_hash_hmac_ripemd_160_96;
        case SADB_X_AALG_MD5:
                return &auth_hash_key_md5;
        case SADB_X_AALG_SHA:
                return &auth_hash_key_sha1;
        case SADB_X_AALG_SHA2_256:
                return &auth_hash_hmac_sha2_256;
        case SADB_X_AALG_SHA2_384:
                return &auth_hash_hmac_sha2_384;
        case SADB_X_AALG_SHA2_512:
                return &auth_hash_hmac_sha2_512;
        case SADB_X_AALG_AES_XCBC_MAC:
                return &auth_hash_aes_xcbc_mac_96;
        }
        return NULL;
}

size_t
ah_authsiz(const struct secasvar *sav)
{
        size_t size;

        if (sav == NULL) {
                return ah_max_authsize;
        }

        size = AUTHSIZE(sav);
        return roundup(size, sizeof(uint32_t));
}

size_t
ah_hdrsiz(const struct secasvar *sav)
{
        size_t size;

        if (sav != NULL) {
                int authsize, rplen, align;

                KASSERT(sav->tdb_authalgxform != NULL);
                /*XXX not right for null algorithm--does it matter??*/

                /* RFC4302: use the correct alignment. */
                align = sizeof(uint32_t);
#ifdef INET6
                if (sav->sah->saidx.dst.sa.sa_family == AF_INET6) {
                        align = sizeof(uint64_t);
                }
#endif
                rplen = HDRSIZE(sav);
                authsize = AUTHSIZE(sav);
                size = roundup(rplen + authsize, align);
        } else {
                /* default guess */
                size = sizeof(struct ah) + sizeof(uint32_t) + ah_max_authsize;
        }
        return size;
}

/*
 * NB: public for use by esp_init.
 */
int
ah_init0(struct secasvar *sav, const struct xformsw *xsp,
         struct cryptoini *cria)
{
        const struct auth_hash *thash;
        int keylen;

        thash = ah_algorithm_lookup(sav->alg_auth);
        if (thash == NULL) {
                DPRINTF("unsupported authentication algorithm %u\n",
                    sav->alg_auth);
                return EINVAL;
        }
        /*
         * Verify the replay state block allocation is consistent with
         * the protocol type.  We check here so we can make assumptions
         * later during protocol processing.
         */
        /* NB: replay state is setup elsewhere (sigh) */
        if (((sav->flags&SADB_X_EXT_OLD) == 0) ^ (sav->replay != NULL)) {
                DPRINTF("replay state block inconsistency, "
                    "%s algorithm %s replay state\n",
                    (sav->flags & SADB_X_EXT_OLD) ? "old" : "new",
                    sav->replay == NULL ? "without" : "with");
                return EINVAL;
        }
        if (sav->key_auth == NULL) {
                DPRINTF("no authentication key for %s algorithm\n",
                    thash->name);
                return EINVAL;
        }
        keylen = _KEYLEN(sav->key_auth);
        if (keylen != thash->keysize && thash->keysize != 0) {
                DPRINTF("invalid keylength %d, algorithm %s requires "
                    "keysize %d\n",
                    keylen, thash->name, thash->keysize);
                return EINVAL;
        }

        sav->tdb_xform = xsp;
        sav->tdb_authalgxform = thash;

        /* Initialize crypto session. */
        memset(cria, 0, sizeof(*cria));
        cria->cri_alg = sav->tdb_authalgxform->type;
        cria->cri_klen = _KEYBITS(sav->key_auth);
        cria->cri_key = _KEYBUF(sav->key_auth);

        return 0;
}

/*
 * ah_init() is called when an SPI is being set up.
 */
static int
ah_init(struct secasvar *sav, const struct xformsw *xsp)
{
        struct cryptoini cria;
        int error;

        error = ah_init0(sav, xsp, &cria);
        if (!error)
                error = crypto_newsession(&sav->tdb_cryptoid,
                                           &cria, crypto_support);
        return error;
}

/*
 * Paranoia.
 *
 * NB: public for use by esp_zeroize (XXX).
 */
void
ah_zeroize(struct secasvar *sav)
{

        if (sav->key_auth) {
                explicit_memset(_KEYBUF(sav->key_auth), 0,
                    _KEYLEN(sav->key_auth));
        }

        crypto_freesession(sav->tdb_cryptoid);
        sav->tdb_cryptoid = 0;
        sav->tdb_authalgxform = NULL;
        sav->tdb_xform = NULL;
}

/*
 * Massage IPv4/IPv6 headers for AH processing.
 */
static int
ah_massage_headers(struct mbuf **m0, int proto, int skip, int alg, int out)
{
        struct mbuf *m = *m0;
        unsigned char *ptr;
        int off, optlen;
#ifdef INET
        struct ip *ip;
#endif
#ifdef INET6
        int count, ip6optlen;
        struct ip6_ext *ip6e;
        struct ip6_hdr ip6;
        int alloc, nxt;
#endif

        switch (proto) {
#ifdef INET
        case AF_INET:
                /*
                 * This is the least painful way of dealing with IPv4 header
                 * and option processing -- just make sure they're in
                 * contiguous memory.
                 */
                *m0 = m = m_pullup(m, skip);
                if (m == NULL) {
                        DPRINTF("m_pullup failed\n");
                        return ENOBUFS;
                }

                /* Fix the IP header */
                ip = mtod(m, struct ip *);
                if (ip4_ah_cleartos)
                        ip->ip_tos = 0;
                ip->ip_ttl = 0;
                ip->ip_sum = 0;
                ip->ip_off = htons(ntohs(ip->ip_off) & ip4_ah_offsetmask);

                if (alg == CRYPTO_MD5_KPDK || alg == CRYPTO_SHA1_KPDK)
                        ip->ip_off &= htons(IP_DF);
                else
                        ip->ip_off = 0;

                ptr = mtod(m, unsigned char *);

                /* IPv4 option processing */
                for (off = sizeof(struct ip); off < skip;) {
                        if (ptr[off] == IPOPT_EOL) {
                                break;
                        } else if (ptr[off] == IPOPT_NOP) {
                                optlen = 1;
                        } else if (off + 1 < skip) {
                                optlen = ptr[off + 1];
                                if (optlen < 2 || off + optlen > skip) {
                                        m_freem(m);
                                        return EINVAL;
                                }
                        } else {
                                m_freem(m);
                                return EINVAL;
                        }

                        switch (ptr[off]) {
                        case IPOPT_NOP:
                        case IPOPT_SECURITY:
                        case 0x85:      /* Extended security. */
                        case 0x86:      /* Commercial security. */
                        case 0x94:      /* Router alert */
                        case 0x95:      /* RFC1770 */
                                break;

                        case IPOPT_LSRR:
                        case IPOPT_SSRR:
                                /*
                                 * On output, if we have either of the
                                 * source routing options, we should
                                 * swap the destination address of the
                                 * IP header with the last address
                                 * specified in the option, as that is
                                 * what the destination's IP header
                                 * will look like.
                                 */
                                if (out)
                                        memcpy(&ip->ip_dst,
                                            ptr + off + optlen -
                                            sizeof(struct in_addr),
                                            sizeof(struct in_addr));
                                /* FALLTHROUGH */

                        default:
                                /* Zeroize all other options. */
                                memset(ptr + off, 0, optlen);
                                break;
                        }

                        off += optlen;

                        /* Sanity check. */
                        if (off > skip) {
                                m_freem(m);
                                return EINVAL;
                        }
                }

                break;
#endif /* INET */

#ifdef INET6
        case AF_INET6:  /* Ugly... */
                /* Copy and "cook" the IPv6 header. */
                m_copydata(m, 0, sizeof(ip6), &ip6);

                /* We don't do IPv6 Jumbograms. */
                if (ip6.ip6_plen == 0) {
                        DPRINTF("unsupported IPv6 jumbogram\n");
                        m_freem(m);
                        return EMSGSIZE;
                }

                ip6.ip6_flow = 0;
                ip6.ip6_hlim = 0;
                ip6.ip6_vfc &= ~IPV6_VERSION_MASK;
                ip6.ip6_vfc |= IPV6_VERSION;

                /* Scoped address handling. */
                if (IN6_IS_SCOPE_LINKLOCAL(&ip6.ip6_src))
                        ip6.ip6_src.s6_addr16[1] = 0;
                if (IN6_IS_SCOPE_LINKLOCAL(&ip6.ip6_dst))
                        ip6.ip6_dst.s6_addr16[1] = 0;

                /* Done with IPv6 header. */
                m_copyback(m, 0, sizeof(struct ip6_hdr), &ip6);

                ip6optlen = skip - sizeof(struct ip6_hdr);

                /* Let's deal with the remaining headers (if any). */
                if (ip6optlen > 0) {
                        if (m->m_len <= skip) {
                                ptr = malloc(ip6optlen, M_XDATA, M_NOWAIT);
                                if (ptr == NULL) {
                                        DPRINTF("failed to allocate "
                                            "memory for IPv6 headers\n");
                                        m_freem(m);
                                        return ENOBUFS;
                                }

                                /*
                                 * Copy all the protocol headers after
                                 * the IPv6 header.
                                 */
                                m_copydata(m, sizeof(struct ip6_hdr),
                                    ip6optlen, ptr);
                                alloc = 1;
                        } else {
                                /* No need to allocate memory. */
                                ptr = mtod(m, unsigned char *) +
                                    sizeof(struct ip6_hdr);
                                alloc = 0;
                        }
                } else
                        break;

                nxt = ip6.ip6_nxt & 0xff; /* Next header type. */

                for (off = 0; off < ip6optlen;) {
                        int noff;

                        if (off + sizeof(*ip6e) > ip6optlen) {
                                goto error6;
                        }
                        ip6e = (struct ip6_ext *)(ptr + off);
                        noff = off + ((ip6e->ip6e_len + 1) << 3);
                        if (noff > ip6optlen) {
                                goto error6;
                        }

                        switch (nxt) {
                        case IPPROTO_HOPOPTS:
                        case IPPROTO_DSTOPTS:
                                /* Zero out mutable options. */
                                for (count = off + sizeof(struct ip6_ext);
                                     count < noff;) {
                                        if (ptr[count] == IP6OPT_PAD1) {
                                                count++;
                                                continue;
                                        }

                                        if (count + 1 >= noff) {
                                                goto error6;
                                        }
                                        optlen = ptr[count + 1] + 2;

                                        if (count + optlen > noff) {
                                                goto error6;
                                        }

                                        if (ptr[count] & IP6OPT_MUTABLE) {
                                                memset(ptr + count, 0, optlen);
                                        }

                                        count += optlen;
                                }
                                if (count != noff) {
                                        goto error6;
                                }
                                /* FALLTHROUGH */

                        case IPPROTO_ROUTING:
                                /* Advance. */
                                off = noff;
                                nxt = ip6e->ip6e_nxt;
                                break;

                        default:
error6:
                                if (alloc)
                                        free(ptr, M_XDATA);
                                m_freem(m);
                                return EINVAL;
                        }
                }

                /* Copyback and free, if we allocated. */
                if (alloc) {
                        m_copyback(m, sizeof(struct ip6_hdr), ip6optlen, ptr);
                        free(ptr, M_XDATA);
                }

                break;
#endif /* INET6 */
        }

        return 0;
}

/*
 * ah_input() gets called to verify that an input packet
 * passes authentication.
 */
static int
ah_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
{
        const struct auth_hash *ahx;
        struct tdb_crypto *tc = NULL;
        struct newah *ah;
        int hl, rplen, authsize, ahsize, error, stat = AH_STAT_HDROPS;
        struct cryptodesc *crda;
        struct cryptop *crp = NULL;
        bool pool_used;
        uint8_t nxt;

        KASSERT(sav != NULL);
        KASSERT(sav->key_auth != NULL);
        KASSERT(sav->tdb_authalgxform != NULL);

        /* Figure out header size. */
        rplen = HDRSIZE(sav);

        /* XXX don't pullup, just copy header */
        M_REGION_GET(ah, struct newah *, m, skip, rplen);
        if (ah == NULL) {
                /* m already freed */
                return ENOBUFS;
        }

        nxt = ah->ah_nxt;

        /* Check replay window, if applicable. */
        if (sav->replay && !ipsec_chkreplay(ntohl(ah->ah_seq), sav)) {
                char buf[IPSEC_LOGSASTRLEN];
                DPRINTF("packet replay failure: %s\n",
                    ipsec_logsastr(sav, buf, sizeof(buf)));
                stat = AH_STAT_REPLAY;
                error = EACCES;
                goto bad;
        }

        /* Verify AH header length. */
        hl = sizeof(struct ah) + (ah->ah_len * sizeof(uint32_t));
        ahx = sav->tdb_authalgxform;
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);
        if (hl != ahsize) {
                char buf[IPSEC_ADDRSTRLEN];
                DPRINTF("bad authenticator length %u (expecting %lu)"
                    " for packet in SA %s/%08lx\n",
                    hl, (u_long)ahsize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                stat = AH_STAT_BADAUTHL;
                error = EACCES;
                goto bad;
        }
        if (skip + ahsize > m->m_pkthdr.len) {
                char buf[IPSEC_ADDRSTRLEN];
                DPRINTF("bad mbuf length %u (expecting >= %lu)"
                    " for packet in SA %s/%08lx\n",
                    m->m_pkthdr.len, (u_long)(skip + ahsize),
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                stat = AH_STAT_BADAUTHL;
                error = EACCES;
                goto bad;
        }

        AH_STATADD(AH_STAT_IBYTES, m->m_pkthdr.len - skip - hl);

        /* Get crypto descriptors. */
        crp = crypto_getreq(1);
        if (crp == NULL) {
                DPRINTF("failed to acquire crypto descriptor\n");
                stat = AH_STAT_CRYPTO;
                error = ENOBUFS;
                goto bad;
        }

        crda = crp->crp_desc;
        KASSERT(crda != NULL);

        crda->crd_skip = 0;
        crda->crd_len = m->m_pkthdr.len;
        crda->crd_inject = skip + rplen;

        /* Authentication operation. */
        crda->crd_alg = ahx->type;
        crda->crd_key = _KEYBUF(sav->key_auth);
        crda->crd_klen = _KEYBITS(sav->key_auth);

        /* Allocate IPsec-specific opaque crypto info. */
        size_t size = sizeof(*tc);
        size_t extra = skip + rplen + authsize;
        size += extra;

        if (__predict_true(size <= ah_pool_item_size)) {
                tc = pool_cache_get(ah_tdb_crypto_pool_cache, PR_NOWAIT);
                pool_used = true;
        } else {
                /* size can exceed on IPv6 packets with large options.  */
                tc = kmem_intr_zalloc(size, KM_NOSLEEP);
                pool_used = false;
        }
        if (tc == NULL) {
                DPRINTF("failed to allocate tdb_crypto\n");
                stat = AH_STAT_CRYPTO;
                error = ENOBUFS;
                goto bad;
        }

        error = m_makewritable(&m, 0, extra, M_NOWAIT);
        if (error) {
                DPRINTF("failed to m_makewritable\n");
                goto bad;
        }

        /*
         * Save the authenticator, the skipped portion of the packet,
         * and the AH header.
         */
        m_copydata(m, 0, extra, (tc + 1));
        /* Zeroize the authenticator on the packet. */
        m_copyback(m, skip + rplen, authsize, ipseczeroes);

        /* "Massage" the packet headers for crypto processing. */
        error = ah_massage_headers(&m, sav->sah->saidx.dst.sa.sa_family,
            skip, ahx->type, 0);
        if (error != 0) {
                /* NB: mbuf is free'd by ah_massage_headers */
                m = NULL;
                goto bad;
        }

    {
        int s = pserialize_read_enter();

        /*
         * Take another reference to the SA for opencrypto callback.
         */
        if (__predict_false(sav->state == SADB_SASTATE_DEAD)) {
                pserialize_read_exit(s);
                stat = AH_STAT_NOTDB;
                error = ENOENT;
                goto bad;
        }
        KEY_SA_REF(sav);
        pserialize_read_exit(s);
    }

        /* Crypto operation descriptor. */
        crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
        crp->crp_flags = CRYPTO_F_IMBUF;
        crp->crp_buf = m;
        crp->crp_callback = ah_input_cb;
        crp->crp_sid = sav->tdb_cryptoid;
        crp->crp_opaque = tc;

        /* These are passed as-is to the callback. */
        tc->tc_spi = sav->spi;
        tc->tc_dst = sav->sah->saidx.dst;
        tc->tc_proto = sav->sah->saidx.proto;
        tc->tc_nxt = nxt;
        tc->tc_protoff = protoff;
        tc->tc_skip = skip;
        tc->tc_sav = sav;

        DPRINTF("hash over %d bytes, skip %d: "
             "crda len %d skip %d inject %d\n",
             crp->crp_ilen, tc->tc_skip,
             crda->crd_len, crda->crd_skip, crda->crd_inject);

        crypto_dispatch(crp);
        return 0;

bad:
        if (tc != NULL) {
                if (__predict_true(pool_used))
                        pool_cache_put(ah_tdb_crypto_pool_cache, tc);
                else
                        kmem_intr_free(tc, size);
        }
        if (crp != NULL)
                crypto_freereq(crp);
        m_freem(m);
        AH_STATINC(stat);
        return error;
}

#ifdef INET6
#define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff) do {                    \
        if (saidx->dst.sa.sa_family == AF_INET6) {                           \
                (void)ipsec6_common_input_cb(m, sav, skip, protoff);         \
        } else {                                                             \
                (void)ipsec4_common_input_cb(m, sav, skip, protoff);         \
        }                                                                    \
} while (0)
#else
#define IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff)                         \
        ((void)ipsec4_common_input_cb(m, sav, skip, protoff))
#endif

/*
 * AH input callback from the crypto driver.
 */
static void
ah_input_cb(struct cryptop *crp)
{
        char buf[IPSEC_ADDRSTRLEN];
        int rplen, ahsize, skip, protoff;
        unsigned char calc[AH_ALEN_MAX];
        struct mbuf *m;
        struct tdb_crypto *tc;
        struct secasvar *sav;
        struct secasindex *saidx;
        uint8_t nxt;
        char *ptr;
        int authsize;
        bool pool_used;
        size_t size;
        IPSEC_DECLARE_LOCK_VARIABLE;

        KASSERT(crp->crp_opaque != NULL);
        tc = crp->crp_opaque;
        skip = tc->tc_skip;
        nxt = tc->tc_nxt;
        protoff = tc->tc_protoff;
        m = crp->crp_buf;

        IPSEC_ACQUIRE_GLOBAL_LOCKS();

        sav = tc->tc_sav;
        saidx = &sav->sah->saidx;
        KASSERTMSG(saidx->dst.sa.sa_family == AF_INET ||
            saidx->dst.sa.sa_family == AF_INET6,
            "unexpected protocol family %u", saidx->dst.sa.sa_family);

        /* Figure out header size. */
        rplen = HDRSIZE(sav);
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);

        size = sizeof(*tc) + skip + rplen + authsize;
        if (__predict_true(size <= ah_pool_item_size))
                pool_used = true;
        else
                pool_used = false;

        /* Check for crypto errors. */
        if (crp->crp_etype) {
                if (sav->tdb_cryptoid != 0)
                        sav->tdb_cryptoid = crp->crp_sid;

                AH_STATINC(AH_STAT_NOXFORM);
                DPRINTF("crypto error %d\n", crp->crp_etype);
                goto bad;
        } else {
                AH_STATINC(AH_STAT_HIST + ah_stats[sav->alg_auth]);
                crypto_freereq(crp);            /* No longer needed. */
                crp = NULL;
        }

        if (ipsec_debug)
                memset(calc, 0, sizeof(calc));

        /* Copy authenticator off the packet. */
        m_copydata(m, skip + rplen, authsize, calc);

        ptr = (char *)(tc + 1);
        const uint8_t *pppp = ptr + skip + rplen;

        /* Verify authenticator. */
        if (!consttime_memequal(pppp, calc, authsize)) {
                DPRINTF("authentication hash mismatch " \
                    "over %d bytes " \
                    "for packet in SA %s/%08lx:\n" \
                    "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x, " \
                    "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x\n",
                    authsize, ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi),
                     calc[0], calc[1], calc[2], calc[3],
                     calc[4], calc[5], calc[6], calc[7],
                     calc[8], calc[9], calc[10], calc[11],
                     pppp[0], pppp[1], pppp[2], pppp[3],
                     pppp[4], pppp[5], pppp[6], pppp[7],
                     pppp[8], pppp[9], pppp[10], pppp[11]);
                AH_STATINC(AH_STAT_BADAUTH);
                goto bad;
        }

        /* Fix the Next Protocol field. */
        ptr[protoff] = nxt;

        /* Copyback the saved (uncooked) network headers. */
        m_copyback(m, 0, skip, ptr);

        if (__predict_true(pool_used))
                pool_cache_put(ah_tdb_crypto_pool_cache, tc);
        else
                kmem_intr_free(tc, size);
        tc = NULL;

        /*
         * Header is now authenticated.
         */
        m->m_flags |= M_AUTHIPHDR;

        /*
         * Update replay sequence number, if appropriate.
         */
        if (sav->replay) {
                uint32_t seq;

                m_copydata(m, skip + offsetof(struct newah, ah_seq),
                    sizeof(seq), &seq);
                if (ipsec_updatereplay(ntohl(seq), sav)) {
                        AH_STATINC(AH_STAT_REPLAY);
                        goto bad;
                }
        }

        /*
         * Remove the AH header and authenticator from the mbuf.
         */
        if (m_striphdr(m, skip, ahsize) != 0) {
                DPRINTF("mangled mbuf chain for SA %s/%08lx\n",
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));

                AH_STATINC(AH_STAT_HDROPS);
                goto bad;
        }

        IPSEC_COMMON_INPUT_CB(m, sav, skip, protoff);

        KEY_SA_UNREF(&sav);
        IPSEC_RELEASE_GLOBAL_LOCKS();
        return;

bad:
        if (sav)
                KEY_SA_UNREF(&sav);
        IPSEC_RELEASE_GLOBAL_LOCKS();
        m_freem(m);
        if (tc != NULL) {
                if (pool_used)
                        pool_cache_put(ah_tdb_crypto_pool_cache, tc);
                else
                        kmem_intr_free(tc, size);
        }
        if (crp != NULL)
                crypto_freereq(crp);
        return;
}

/*
 * AH output routine, called by ipsec[46]_process_packet().
 */
static int
ah_output(struct mbuf *m, const struct ipsecrequest *isr, struct secasvar *sav,
    int skip, int protoff, int flags)
{
        char buf[IPSEC_ADDRSTRLEN];
        const struct auth_hash *ahx;
        struct cryptodesc *crda;
        struct tdb_crypto *tc;
        struct mbuf *mi;
        struct cryptop *crp;
        uint16_t iplen;
        int error, rplen, authsize, ahsize, maxpacketsize, roff;
        uint8_t prot;
        struct newah *ah;
        size_t ipoffs;
        bool pool_used;

        KASSERT(sav != NULL);
        KASSERT(sav->tdb_authalgxform != NULL);
        ahx = sav->tdb_authalgxform;

        AH_STATINC(AH_STAT_OUTPUT);

        /* Figure out header size. */
        rplen = HDRSIZE(sav);
        authsize = AUTHSIZE(sav);
        ahsize = ah_hdrsiz(sav);

        /* Check for maximum packet size violations. */
        switch (sav->sah->saidx.dst.sa.sa_family) {
#ifdef INET
        case AF_INET:
                maxpacketsize = IP_MAXPACKET;
                ipoffs = offsetof(struct ip, ip_len);
                break;
#endif
#ifdef INET6
        case AF_INET6:
                maxpacketsize = IPV6_MAXPACKET;
                ipoffs = offsetof(struct ip6_hdr, ip6_plen);
                break;
#endif
        default:
                DPRINTF("unknown/unsupported protocol "
                    "family %u, SA %s/%08lx\n",
                    sav->sah->saidx.dst.sa.sa_family,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                AH_STATINC(AH_STAT_NOPF);
                error = EPFNOSUPPORT;
                goto bad;
        }
        if (ahsize + m->m_pkthdr.len > maxpacketsize) {
                DPRINTF("packet in SA %s/%08lx got too big "
                    "(len %u, max len %u)\n",
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi),
                    ahsize + m->m_pkthdr.len, maxpacketsize);
                AH_STATINC(AH_STAT_TOOBIG);
                error = EMSGSIZE;
                goto bad;
        }

        /* Update the counters. */
        AH_STATADD(AH_STAT_OBYTES, m->m_pkthdr.len - skip);

        m = m_clone(m);
        if (m == NULL) {
                DPRINTF("cannot clone mbuf chain, SA %s/%08lx\n",
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                AH_STATINC(AH_STAT_HDROPS);
                error = ENOBUFS;
                goto bad;
        }

        /* Inject AH header. */
        mi = m_makespace(m, skip, ahsize, &roff);
        if (mi == NULL) {
                DPRINTF("failed to inject %u byte AH header for SA "
                    "%s/%08lx\n", ahsize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                AH_STATINC(AH_STAT_HDROPS);
                error = ENOBUFS;
                goto bad;
        }

        /*
         * The AH header is guaranteed by m_makespace() to be in
         * contiguous memory, at roff bytes offset into the returned mbuf.
         */
        ah = (struct newah *)(mtod(mi, char *) + roff);

        /* Initialize the AH header. */
        m_copydata(m, protoff, sizeof(uint8_t), &ah->ah_nxt);
        ah->ah_len = (ahsize - sizeof(struct ah)) / sizeof(uint32_t);
        ah->ah_reserve = 0;
        ah->ah_spi = sav->spi;

        /* Zeroize authenticator. */
        m_copyback(m, skip + rplen, authsize, ipseczeroes);

        /* Zeroize padding. */
        m_copyback(m, skip + rplen + authsize, ahsize - (rplen + authsize),
            ipseczeroes);

        /* Insert packet replay counter, as requested.  */
        if (sav->replay) {
                if (sav->replay->count == ~0 &&
                    (sav->flags & SADB_X_EXT_CYCSEQ) == 0) {
                        DPRINTF("replay counter wrapped for SA %s/%08lx\n",
                            ipsec_address(&sav->sah->saidx.dst, buf,
                            sizeof(buf)), (u_long) ntohl(sav->spi));
                        AH_STATINC(AH_STAT_WRAP);
                        error = EINVAL;
                        goto bad;
                }
#ifdef IPSEC_DEBUG
                /* Emulate replay attack when ipsec_replay is TRUE. */
                if (!ipsec_replay)
#endif
                        sav->replay->count++;
                ah->ah_seq = htonl(sav->replay->count);
        }

        /* Get crypto descriptors. */
        crp = crypto_getreq(1);
        if (crp == NULL) {
                DPRINTF("failed to acquire crypto descriptors\n");
                AH_STATINC(AH_STAT_CRYPTO);
                error = ENOBUFS;
                goto bad;
        }

        crda = crp->crp_desc;

        crda->crd_skip = 0;
        crda->crd_inject = skip + rplen;
        crda->crd_len = m->m_pkthdr.len;

        /* Authentication operation. */
        crda->crd_alg = ahx->type;
        crda->crd_key = _KEYBUF(sav->key_auth);
        crda->crd_klen = _KEYBITS(sav->key_auth);

        /* Allocate IPsec-specific opaque crypto info. */
        size_t size = sizeof(*tc) + skip;

        if (__predict_true(size <= ah_pool_item_size)) {
                tc = pool_cache_get(ah_tdb_crypto_pool_cache, PR_NOWAIT);
                pool_used = true;
        } else {
                /* size can exceed on IPv6 packets with large options.  */
                tc = kmem_intr_zalloc(size, KM_NOSLEEP);
                pool_used = false;
        }
        if (tc == NULL) {
                DPRINTF("failed to allocate tdb_crypto\n");
                AH_STATINC(AH_STAT_CRYPTO);
                error = ENOBUFS;
                goto bad_crp;
        }

        uint8_t *pext = (char *)(tc + 1);
        /* Save the skipped portion of the packet. */
        m_copydata(m, 0, skip, pext);

        /*
         * Fix IP header length on the header used for
         * authentication. We don't need to fix the original
         * header length as it will be fixed by our caller.
         */
        memcpy(&iplen, pext + ipoffs, sizeof(iplen));
        iplen = htons(ntohs(iplen) + ahsize);
        m_copyback(m, ipoffs, sizeof(iplen), &iplen);

        /* Fix the Next Header field in saved header. */
        pext[protoff] = IPPROTO_AH;

        /* Update the Next Protocol field in the IP header. */
        prot = IPPROTO_AH;
        m_copyback(m, protoff, sizeof(prot), &prot);

        /* "Massage" the packet headers for crypto processing. */
        error = ah_massage_headers(&m, sav->sah->saidx.dst.sa.sa_family,
            skip, ahx->type, 1);
        if (error != 0) {
                m = NULL;       /* mbuf was free'd by ah_massage_headers. */
                goto bad_tc;
        }

    {
        int s = pserialize_read_enter();

        /*
         * Take another reference to the SP and the SA for opencrypto callback.
         */
        if (__predict_false(isr->sp->state == IPSEC_SPSTATE_DEAD ||
            sav->state == SADB_SASTATE_DEAD)) {
                pserialize_read_exit(s);
                AH_STATINC(AH_STAT_NOTDB);
                error = ENOENT;
                goto bad_tc;
        }
        KEY_SP_REF(isr->sp);
        KEY_SA_REF(sav);
        pserialize_read_exit(s);
    }

        /* Crypto operation descriptor. */
        crp->crp_ilen = m->m_pkthdr.len; /* Total input length. */
        crp->crp_flags = CRYPTO_F_IMBUF;
        crp->crp_buf = m;
        crp->crp_callback = ah_output_cb;
        crp->crp_sid = sav->tdb_cryptoid;
        crp->crp_opaque = tc;

        /* These are passed as-is to the callback. */
        tc->tc_isr = isr;
        tc->tc_spi = sav->spi;
        tc->tc_dst = sav->sah->saidx.dst;
        tc->tc_proto = sav->sah->saidx.proto;
        tc->tc_skip = skip;
        tc->tc_protoff = protoff;
        tc->tc_flags = flags;
        tc->tc_sav = sav;

        crypto_dispatch(crp);
        return 0;

bad_tc:
        if (__predict_true(pool_used))
                pool_cache_put(ah_tdb_crypto_pool_cache, tc);
        else
                kmem_intr_free(tc, size);
bad_crp:
        crypto_freereq(crp);
bad:
        m_freem(m);
        return error;
}

/*
 * AH output callback from the crypto driver.
 */
static void
ah_output_cb(struct cryptop *crp)
{
        int skip;
        struct tdb_crypto *tc;
        const struct ipsecrequest *isr;
        struct secasvar *sav;
        struct mbuf *m;
        void *ptr;
        int flags;
        size_t size;
        bool pool_used;
        IPSEC_DECLARE_LOCK_VARIABLE;

        KASSERT(crp->crp_opaque != NULL);
        tc = crp->crp_opaque;
        skip = tc->tc_skip;
        ptr = (tc + 1);
        m = crp->crp_buf;
        size = sizeof(*tc) + skip;
        pool_used = size <= ah_pool_item_size;

        IPSEC_ACQUIRE_GLOBAL_LOCKS();

        isr = tc->tc_isr;
        sav = tc->tc_sav;

        /* Check for crypto errors. */
        if (crp->crp_etype) {
                if (sav->tdb_cryptoid != 0)
                        sav->tdb_cryptoid = crp->crp_sid;

                AH_STATINC(AH_STAT_NOXFORM);
                DPRINTF("crypto error %d\n", crp->crp_etype);
                goto bad;
        }

        AH_STATINC(AH_STAT_HIST + ah_stats[sav->alg_auth]);

        /*
         * Copy original headers (with the new protocol number) back
         * in place.
         */
        m_copyback(m, 0, skip, ptr);

        flags = tc->tc_flags;
        /* No longer needed. */
        if (__predict_true(pool_used))
                pool_cache_put(ah_tdb_crypto_pool_cache, tc);
        else
                kmem_intr_free(tc, size);
        crypto_freereq(crp);

#ifdef IPSEC_DEBUG
        /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
        if (ipsec_integrity) {
                int alen;

                /*
                 * Corrupt HMAC if we want to test integrity verification of
                 * the other side.
                 */
                alen = AUTHSIZE(sav);
                m_copyback(m, m->m_pkthdr.len - alen, alen, ipseczeroes);
        }
#endif

        /* NB: m is reclaimed by ipsec_process_done. */
        (void)ipsec_process_done(m, isr, sav, flags);
        KEY_SA_UNREF(&sav);
        KEY_SP_UNREF(&isr->sp);
        IPSEC_RELEASE_GLOBAL_LOCKS();
        return;
bad:
        if (sav)
                KEY_SA_UNREF(&sav);
        KEY_SP_UNREF(&isr->sp);
        IPSEC_RELEASE_GLOBAL_LOCKS();
        m_freem(m);
        if (__predict_true(pool_used))
                pool_cache_put(ah_tdb_crypto_pool_cache, tc);
        else
                kmem_intr_free(tc, size);
        crypto_freereq(crp);
}

static struct xformsw ah_xformsw = {
        .xf_type        = XF_AH,
        .xf_flags       = XFT_AUTH,
        .xf_name        = "IPsec AH",
        .xf_init        = ah_init,
        .xf_zeroize     = ah_zeroize,
        .xf_input       = ah_input,
        .xf_output      = ah_output,
        .xf_next        = NULL,
};

void
ah_attach(void)
{
        ahstat_percpu = percpu_alloc(sizeof(uint64_t) * AH_NSTATS);

#define MAXAUTHSIZE(name)                                               \
        if ((auth_hash_ ## name).authsize > ah_max_authsize)            \
                ah_max_authsize = (auth_hash_ ## name).authsize

        ah_max_authsize = 0;
        MAXAUTHSIZE(null);
        MAXAUTHSIZE(md5);
        MAXAUTHSIZE(sha1);
        MAXAUTHSIZE(key_md5);
        MAXAUTHSIZE(key_sha1);
        MAXAUTHSIZE(hmac_md5);
        MAXAUTHSIZE(hmac_sha1);
        MAXAUTHSIZE(hmac_ripemd_160);
        MAXAUTHSIZE(hmac_md5_96);
        MAXAUTHSIZE(hmac_sha1_96);
        MAXAUTHSIZE(hmac_ripemd_160_96);
        MAXAUTHSIZE(hmac_sha2_256);
        MAXAUTHSIZE(hmac_sha2_384);
        MAXAUTHSIZE(hmac_sha2_512);
        MAXAUTHSIZE(aes_xcbc_mac_96);
        MAXAUTHSIZE(gmac_aes_128);
        MAXAUTHSIZE(gmac_aes_192);
        MAXAUTHSIZE(gmac_aes_256);
        IPSECLOG(LOG_DEBUG, "ah_max_authsize=%d\n", ah_max_authsize);

#undef MAXAUTHSIZE

        ah_pool_item_size = sizeof(struct tdb_crypto) +
            sizeof(struct ip) + MAX_IPOPTLEN +
            sizeof(struct ah) + sizeof(uint32_t) + ah_max_authsize;
        ah_tdb_crypto_pool_cache = pool_cache_init(ah_pool_item_size,
            coherency_unit, 0, 0, "ah_tdb_crypto", NULL, IPL_SOFTNET,
            NULL, NULL, NULL);

        xform_register(&ah_xformsw);
}