/*      $NetBSD: xform_esp.c,v 1.107 2024/07/05 04:31:54 rin Exp $      */
/*      $FreeBSD: xform_esp.c,v 1.2.2.1 2003/01/24 05:11:36 sam Exp $   */
/*      $OpenBSD: ip_esp.c,v 1.69 2001/06/26 06:18:59 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.
 *
 * Copyright (C) 1995, 1996, 1997, 1998, 1999 by John Ioannidis,
 * Angelos D. Keromytis and Niels Provos.
 * 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_esp.c,v 1.107 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/cprng.h>
#include <sys/pool.h>
#include <sys/pserialize.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/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/esp.h>
#include <netipsec/esp_var.h>
#include <netipsec/xform.h>

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

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

#include <opencrypto/cryptodev.h>

percpu_t *espstat_percpu;

int esp_enable = 1;

static int esp_max_ivlen;               /* max iv length over all algorithms */

static void esp_input_cb(struct cryptop *op);
static void esp_output_cb(struct cryptop *crp);

const uint8_t esp_stats[256] = { SADB_EALG_STATS_INIT };

static pool_cache_t esp_tdb_crypto_pool_cache;
static size_t esp_pool_item_size;

/*
 * NB: this is public for use by the PF_KEY support.
 * NB: if you add support here; be sure to add code to esp_attach below!
 */
const struct enc_xform *
esp_algorithm_lookup(int alg)
{

        switch (alg) {
        case SADB_EALG_DESCBC:
                return &enc_xform_des;
        case SADB_EALG_3DESCBC:
                return &enc_xform_3des;
        case SADB_X_EALG_AES:
                return &enc_xform_aes;
        case SADB_X_EALG_BLOWFISHCBC:
                return &enc_xform_blf;
        case SADB_X_EALG_CAST128CBC:
                return &enc_xform_cast5;
        case SADB_X_EALG_SKIPJACK:
                return &enc_xform_skipjack;
        case SADB_X_EALG_CAMELLIACBC:
                return &enc_xform_camellia;
        case SADB_X_EALG_AESCTR:
                return &enc_xform_aes_ctr;
        case SADB_X_EALG_AESGCM16:
                return &enc_xform_aes_gcm;
        case SADB_X_EALG_AESGMAC:
                return &enc_xform_aes_gmac;
        case SADB_EALG_NULL:
                return &enc_xform_null;
        }
        return NULL;
}

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

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

                /*
                 *   base header size
                 * + iv length for CBC mode
                 * + max pad length
                 * + sizeof(esp trailer)
                 * + icv length (if any).
                 */
                if (sav->flags & SADB_X_EXT_OLD)
                        size = sizeof(struct esp);
                else
                        size = sizeof(struct newesp);
                size += sav->tdb_encalgxform->ivsize + 9 +
                    sizeof(struct esptail);

                /*XXX need alg check???*/
                if (sav->tdb_authalgxform != NULL && sav->replay)
                        size += ah_authsiz(sav);
        } else {
                /*
                 *   base header size
                 * + max iv length for CBC mode
                 * + max pad length
                 * + sizeof(esp trailer)
                 * + max icv supported.
                 */
                size = sizeof(struct newesp) + esp_max_ivlen + 9 +
                    sizeof(struct esptail) + ah_authsiz(NULL);
        }
        return size;
}

/*
 * esp_init() is called when an SPI is being set up.
 */
static int
esp_init(struct secasvar *sav, const struct xformsw *xsp)
{
        const struct enc_xform *txform;
        struct cryptoini cria, crie, *cr;
        int keylen;
        int error;

        txform = esp_algorithm_lookup(sav->alg_enc);
        if (txform == NULL) {
                DPRINTF("unsupported encryption algorithm %d\n",
                    sav->alg_enc);
                return EINVAL;
        }
        if (sav->key_enc == NULL) {
                DPRINTF("no encoding key for %s algorithm\n",
                    txform->name);
                return EINVAL;
        }
        if ((sav->flags&(SADB_X_EXT_OLD|SADB_X_EXT_IV4B)) == SADB_X_EXT_IV4B) {
                DPRINTF("4-byte IV not supported with protocol\n");
                return EINVAL;
        }
        keylen = _KEYLEN(sav->key_enc);
        if (txform->minkey > keylen || keylen > txform->maxkey) {
                DPRINTF("invalid key length %u, must be in "
                    "the range [%u..%u] for algorithm %s\n",
                    keylen, txform->minkey, txform->maxkey, txform->name);
                return EINVAL;
        }

        sav->ivlen = txform->ivsize;

        /*
         * Setup AH-related state.
         */
        if (sav->alg_auth != 0) {
                error = ah_init0(sav, xsp, &cria);
                if (error)
                        return error;
        }

        /* NB: override anything set in ah_init0 */
        sav->tdb_xform = xsp;
        sav->tdb_encalgxform = txform;

        switch (sav->alg_enc) {
        case SADB_X_EALG_AESGCM16:
        case SADB_X_EALG_AESGMAC:
                switch (keylen) {
                case 20:
                        sav->alg_auth = SADB_X_AALG_AES128GMAC;
                        sav->tdb_authalgxform = &auth_hash_gmac_aes_128;
                        break;
                case 28:
                        sav->alg_auth = SADB_X_AALG_AES192GMAC;
                        sav->tdb_authalgxform = &auth_hash_gmac_aes_192;
                        break;
                case 36:
                        sav->alg_auth = SADB_X_AALG_AES256GMAC;
                        sav->tdb_authalgxform = &auth_hash_gmac_aes_256;
                        break;
                default:
                        DPRINTF("invalid key length %u, must be either of "
                            "20, 28 or 36\n", keylen);
                        return EINVAL;
                }

                memset(&cria, 0, sizeof(cria));
                cria.cri_alg = sav->tdb_authalgxform->type;
                cria.cri_klen = _KEYBITS(sav->key_enc);
                cria.cri_key = _KEYBUF(sav->key_enc);
                break;
        default:
                break;
        }

        /* Initialize crypto session. */
        memset(&crie, 0, sizeof(crie));
        crie.cri_alg = sav->tdb_encalgxform->type;
        crie.cri_klen = _KEYBITS(sav->key_enc);
        crie.cri_key = _KEYBUF(sav->key_enc);
        /* XXX Rounds ? */

        if (sav->tdb_authalgxform && sav->tdb_encalgxform) {
                /* init both auth & enc */
                crie.cri_next = &cria;
                cr = &crie;
        } else if (sav->tdb_encalgxform) {
                cr = &crie;
        } else if (sav->tdb_authalgxform) {
                cr = &cria;
        } else {
                /* XXX cannot happen? */
                DPRINTF("no encoding OR authentication xform!\n");
                return EINVAL;
        }

        return crypto_newsession(&sav->tdb_cryptoid, cr, crypto_support);
}

/*
 * Paranoia.
 */
static void
esp_zeroize(struct secasvar *sav)
{
        /* NB: ah_zerorize free's the crypto session state */
        ah_zeroize(sav);

        if (sav->key_enc) {
                explicit_memset(_KEYBUF(sav->key_enc), 0,
                    _KEYLEN(sav->key_enc));
        }
        sav->tdb_encalgxform = NULL;
        sav->tdb_xform = NULL;
}

/*
 * ESP input processing, called (eventually) through the protocol switch.
 */
static int
esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
{
        const struct auth_hash *esph;
        const struct enc_xform *espx;
        struct tdb_crypto *tc;
        int plen, alen, hlen, error, stat = ESP_STAT_CRYPTO;
        struct newesp *esp;
        struct cryptodesc *crde;
        struct cryptop *crp;

        KASSERT(sav != NULL);
        KASSERT(sav->tdb_encalgxform != NULL);
        if (__predict_false((skip & 3) != 0 || (m->m_pkthdr.len & 3) != 0)) {
                DPRINTF("%s: misaligned packet, skip %u pkt len %u", __func__,
                    skip, m->m_pkthdr.len);
                stat = ESP_STAT_BADILEN; /* Same as FreeBSD */
                error = EINVAL;
                goto out;
        }

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

        esph = sav->tdb_authalgxform;
        espx = sav->tdb_encalgxform;
        KASSERT(espx != NULL);

        /* Determine the ESP header length */
        if (sav->flags & SADB_X_EXT_OLD)
                hlen = sizeof(struct esp) + sav->ivlen;
        else
                hlen = sizeof(struct newesp) + sav->ivlen;
        /* Authenticator hash size */
        alen = esph ? esph->authsize : 0;

        /*
         * Verify payload length is multiple of encryption algorithm block
         * size.
         *
         * The payload must also be 4-byte-aligned. This is implicitly
         * verified here too, since the blocksize is always 4-byte-aligned.
         */
        plen = m->m_pkthdr.len - (skip + hlen + alen);
        KASSERT((espx->blocksize & 3) == 0);
        if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
                char buf[IPSEC_ADDRSTRLEN];
                DPRINTF("payload of %d octets not a multiple of %d octets,"
                    "  SA %s/%08lx\n", plen, espx->blocksize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                stat = ESP_STAT_BADILEN;
                error = EINVAL;
                goto out;
        }

        /*
         * Check sequence number.
         */
        if (esph && sav->replay && !ipsec_chkreplay(ntohl(esp->esp_seq), sav)) {
                char logbuf[IPSEC_LOGSASTRLEN];
                DPRINTF("packet replay check for %s\n",
                    ipsec_logsastr(sav, logbuf, sizeof(logbuf)));
                stat = ESP_STAT_REPLAY;
                error = EACCES;
                goto out;
        }

        /* Update the counters */
        ESP_STATADD(ESP_STAT_IBYTES, plen);

        /* Get crypto descriptors */
        crp = crypto_getreq(esph ? 2 : 1);
        if (crp == NULL) {
                DPRINTF("failed to acquire crypto descriptors\n");
                error = ENOBUFS;
                goto out;
        }

        /* Get IPsec-specific opaque pointer */
        size_t extra __diagused = esph == NULL ? 0 : alen;
        KASSERTMSG(sizeof(*tc) + extra <= esp_pool_item_size,
            "sizeof(*tc) + extra=%zu > esp_pool_item_size=%zu\n",
            sizeof(*tc) + extra, esp_pool_item_size);
        tc = pool_cache_get(esp_tdb_crypto_pool_cache, PR_NOWAIT);
        if (tc == NULL) {
                DPRINTF("failed to allocate tdb_crypto\n");
                error = ENOBUFS;
                goto out1;
        }

        error = m_makewritable(&m, 0, m->m_pkthdr.len, M_NOWAIT);
        if (error) {
                DPRINTF("m_makewritable failed\n");
                goto out2;
        }

        if (esph) {
                struct cryptodesc *crda;

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

                /* Authentication descriptor */
                crda->crd_skip = skip;
                if (espx->type == CRYPTO_AES_GCM_16)
                        crda->crd_len = hlen - sav->ivlen;
                else
                        crda->crd_len = m->m_pkthdr.len - (skip + alen);
                crda->crd_inject = m->m_pkthdr.len - alen;

                crda->crd_alg = esph->type;
                if (espx->type == CRYPTO_AES_GCM_16 ||
                    espx->type == CRYPTO_AES_GMAC) {
                        crda->crd_key = _KEYBUF(sav->key_enc);
                        crda->crd_klen = _KEYBITS(sav->key_enc);
                } else {
                        crda->crd_key = _KEYBUF(sav->key_auth);
                        crda->crd_klen = _KEYBITS(sav->key_auth);
                }

                /* Copy the authenticator */
                m_copydata(m, m->m_pkthdr.len - alen, alen, (tc + 1));

                /* Chain authentication request */
                crde = crda->crd_next;
        } else {
                crde = crp->crp_desc;
        }

    {
        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 = ESP_STAT_NOTDB;
                error = ENOENT;
                goto out2;
        }
        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 = esp_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_protoff = protoff;
        tc->tc_skip = skip;
        tc->tc_sav = sav;

        /* Decryption descriptor */
        KASSERTMSG(crde != NULL, "null esp crypto descriptor");
        crde->crd_skip = skip + hlen;
        if (espx->type == CRYPTO_AES_GMAC)
                crde->crd_len = 0;
        else
                crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
        crde->crd_inject = skip + hlen - sav->ivlen;
        crde->crd_alg = espx->type;
        crde->crd_key = _KEYBUF(sav->key_enc);
        crde->crd_klen = _KEYBITS(sav->key_enc);
        /* XXX Rounds ? */

        crypto_dispatch(crp);
        return 0;

out2:
        pool_cache_put(esp_tdb_crypto_pool_cache, tc);
out1:
        crypto_freereq(crp);
out:
        ESP_STATINC(stat);
        m_freem(m);
        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

/*
 * ESP input callback from the crypto driver.
 */
static void
esp_input_cb(struct cryptop *crp)
{
        char buf[IPSEC_ADDRSTRLEN];
        uint8_t lastthree[3], aalg[AH_ALEN_MAX];
        int hlen, skip, protoff;
        struct mbuf *m;
        const struct auth_hash *esph;
        struct tdb_crypto *tc;
        struct secasvar *sav;
        struct secasindex *saidx;
        void *ptr;
        IPSEC_DECLARE_LOCK_VARIABLE;

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

        tc = crp->crp_opaque;
        skip = tc->tc_skip;
        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);

        esph = sav->tdb_authalgxform;

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

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

        ESP_STATINC(ESP_STAT_HIST + esp_stats[sav->alg_enc]);

        /* If authentication was performed, check now. */
        if (esph != NULL) {
                /*
                 * If we have a tag, it means an IPsec-aware NIC did
                 * the verification for us.  Otherwise we need to
                 * check the authentication calculation.
                 */
                AH_STATINC(AH_STAT_HIST + ah_stats[sav->alg_auth]);
                /* Copy the authenticator from the packet */
                m_copydata(m, m->m_pkthdr.len - esph->authsize,
                        esph->authsize, aalg);

                ptr = (tc + 1);

                /* Verify authenticator */
                if (!consttime_memequal(ptr, aalg, esph->authsize)) {
                        DPRINTF("authentication hash mismatch "
                            "for packet in SA %s/%08lx\n",
                            ipsec_address(&saidx->dst, buf,
                            sizeof(buf)), (u_long) ntohl(sav->spi));
                        ESP_STATINC(ESP_STAT_BADAUTH);
                        goto bad;
                }

                /* Remove trailing authenticator */
                m_adj(m, -(esph->authsize));
        }

        /* Release the crypto descriptors */
        pool_cache_put(esp_tdb_crypto_pool_cache, tc);
        tc = NULL;
        crypto_freereq(crp);
        crp = NULL;

        /*
         * Packet is now decrypted.
         */
        m->m_flags |= M_DECRYPTED;

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

                m_copydata(m, skip + offsetof(struct newesp, esp_seq),
                    sizeof(seq), &seq);
                if (ipsec_updatereplay(ntohl(seq), sav)) {
                        char logbuf[IPSEC_LOGSASTRLEN];
                        DPRINTF("packet replay check for %s\n",
                            ipsec_logsastr(sav, logbuf, sizeof(logbuf)));
                        ESP_STATINC(ESP_STAT_REPLAY);
                        goto bad;
                }
        }

        /* Determine the ESP header length */
        if (sav->flags & SADB_X_EXT_OLD)
                hlen = sizeof(struct esp) + sav->ivlen;
        else
                hlen = sizeof(struct newesp) + sav->ivlen;

        /* Remove the ESP header and IV from the mbuf. */
        if (m_striphdr(m, skip, hlen) != 0) {
                ESP_STATINC(ESP_STAT_HDROPS);
                DPRINTF("bad mbuf chain, SA %s/%08lx\n",
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                goto bad;
        }

        /* Save the last three bytes of decrypted data */
        m_copydata(m, m->m_pkthdr.len - 3, 3, lastthree);

        /* Verify pad length */
        if (lastthree[1] + 2 > m->m_pkthdr.len - skip) {
                ESP_STATINC(ESP_STAT_BADILEN);
                DPRINTF("invalid padding length %d "
                    "for %u byte packet in SA %s/%08lx\n",
                    lastthree[1], m->m_pkthdr.len - skip,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                goto bad;
        }

        /* Verify correct decryption by checking the last padding bytes */
        if ((sav->flags & SADB_X_EXT_PMASK) != SADB_X_EXT_PRAND) {
                if (lastthree[1] != lastthree[0] && lastthree[1] != 0) {
                        ESP_STATINC(ESP_STAT_BADENC);
                        DPRINTF("decryption failed for packet in SA "
                            "%s/%08lx\n",
                            ipsec_address(&sav->sah->saidx.dst, buf,
                            sizeof(buf)), (u_long) ntohl(sav->spi));
                        DPRINTF("%x %x\n", lastthree[0],
                            lastthree[1]);
                        goto bad;
                }
        }

        /* Trim the mbuf chain to remove trailing authenticator and padding */
        m_adj(m, -(lastthree[1] + 2));

        /* Restore the Next Protocol field */
        m_copyback(m, protoff, sizeof(uint8_t), lastthree + 2);

        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)
                pool_cache_put(esp_tdb_crypto_pool_cache, tc);
        if (crp != NULL)
                crypto_freereq(crp);
}

/*
 * ESP output routine, called by ipsec[46]_process_packet().
 */
static int
esp_output(struct mbuf *m, const struct ipsecrequest *isr, struct secasvar *sav,
    int skip, int protoff, int flags)
{
        char buf[IPSEC_ADDRSTRLEN];
        const struct enc_xform *espx;
        const struct auth_hash *esph;
        int hlen, rlen, tlen, padlen, blks, alen, i, roff;
        struct mbuf *mo = NULL;
        struct tdb_crypto *tc;
        struct secasindex *saidx;
        unsigned char *tail;
        uint8_t prot;
        int error, maxpacketsize;
        struct esptail *esptail;
        struct cryptodesc *crde, *crda;
        struct cryptop *crp;

        esph = sav->tdb_authalgxform;
        espx = sav->tdb_encalgxform;
        KASSERT(espx != NULL);

        /* Determine the ESP header length */
        if (sav->flags & SADB_X_EXT_OLD)
                hlen = sizeof(struct esp) + sav->ivlen;
        else
                hlen = sizeof(struct newesp) + sav->ivlen;
        /* Authenticator hash size */
        alen = esph ? esph->authsize : 0;

        /*
         * NB: The null encoding transform has a blocksize of 4
         *     so that headers are properly aligned.
         */
        blks = espx->blocksize;         /* IV blocksize */

        /* Raw payload length. */
        rlen = m->m_pkthdr.len - skip;

        /* Encryption padding. */
        padlen = ((blks - ((rlen + sizeof(struct esptail)) % blks)) % blks);

        /* Length of what we append (tail). */
        tlen = padlen + sizeof(struct esptail) + alen;

        ESP_STATINC(ESP_STAT_OUTPUT);

        saidx = &sav->sah->saidx;
        /* Check for maximum packet size violations. */
        switch (saidx->dst.sa.sa_family) {
#ifdef INET
        case AF_INET:
                maxpacketsize = IP_MAXPACKET;
                break;
#endif
#ifdef INET6
        case AF_INET6:
                maxpacketsize = IPV6_MAXPACKET;
                break;
#endif
        default:
                DPRINTF("unknown/unsupported protocol family %d, "
                    "SA %s/%08lx\n", saidx->dst.sa.sa_family,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long)ntohl(sav->spi));
                ESP_STATINC(ESP_STAT_NOPF);
                error = EPFNOSUPPORT;
                goto bad;
        }
        if (skip + hlen + rlen + tlen > maxpacketsize) {
                DPRINTF("packet in SA %s/%08lx got too big (len %u, "
                    "max len %u)\n",
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi),
                    skip + hlen + rlen + tlen, maxpacketsize);
                ESP_STATINC(ESP_STAT_TOOBIG);
                error = EMSGSIZE;
                goto bad;
        }

        /* Update the counters. */
        ESP_STATADD(ESP_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(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                ESP_STATINC(ESP_STAT_HDROPS);
                error = ENOBUFS;
                goto bad;
        }

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

        /* Initialize ESP header. */
        memcpy(mtod(mo, char *) + roff, &sav->spi, sizeof(uint32_t));
        if (sav->replay) {
                uint32_t replay;

#ifdef IPSEC_DEBUG
                /* Emulate replay attack when ipsec_replay is TRUE. */
                if (ipsec_replay)
                        replay = htonl(sav->replay->count);
                else
#endif
                        replay = htonl(atomic_inc_32_nv(&sav->replay->count));

                memcpy(mtod(mo,char *) + roff + sizeof(uint32_t), &replay,
                    sizeof(uint32_t));
        }

        /*
         * Grow the mbuf, we will append data at the tail.
         */
        tail = m_pad(m, tlen);
        if (tail == NULL) {
                DPRINTF("m_pad failed for SA %s/%08lx\n",
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi));
                m = NULL;
                error = ENOBUFS;
                goto bad;
        }

        /*
         * Add padding: random, zero, or self-describing.
         */
        switch (sav->flags & SADB_X_EXT_PMASK) {
        case SADB_X_EXT_PSEQ:
                for (i = 0; i < padlen; i++)
                        tail[i] = i + 1;
                break;
        case SADB_X_EXT_PRAND:
                (void)cprng_fast(tail, padlen);
                break;
        case SADB_X_EXT_PZERO:
        default:
                memset(tail, 0, padlen);
                break;
        }

        /* Build the ESP Trailer. */
        esptail = (struct esptail *)&tail[padlen];
        esptail->esp_padlen = padlen;
        m_copydata(m, protoff, sizeof(uint8_t), &esptail->esp_nxt);

        /* Fix Next Protocol in IPv4/IPv6 header. */
        prot = IPPROTO_ESP;
        m_copyback(m, protoff, sizeof(uint8_t), &prot);

        /* Get crypto descriptors. */
        crp = crypto_getreq(esph ? 2 : 1);
        if (crp == NULL) {
                DPRINTF("failed to acquire crypto descriptors\n");
                ESP_STATINC(ESP_STAT_CRYPTO);
                error = ENOBUFS;
                goto bad;
        }

        /* Get the descriptors. */
        crde = crp->crp_desc;
        crda = crde->crd_next;

        /* Encryption descriptor. */
        crde->crd_skip = skip + hlen;
        if (espx->type == CRYPTO_AES_GMAC)
                crde->crd_len = 0;
        else
                crde->crd_len = m->m_pkthdr.len - (skip + hlen + alen);
        crde->crd_flags = CRD_F_ENCRYPT;
        crde->crd_inject = skip + hlen - sav->ivlen;
        crde->crd_alg = espx->type;
        crde->crd_key = _KEYBUF(sav->key_enc);
        crde->crd_klen = _KEYBITS(sav->key_enc);
        /* XXX Rounds ? */

        /* IPsec-specific opaque crypto info. */
        tc = pool_cache_get(esp_tdb_crypto_pool_cache, PR_NOWAIT);
        if (tc == NULL) {
                crypto_freereq(crp);
                DPRINTF("failed to allocate tdb_crypto\n");
                ESP_STATINC(ESP_STAT_CRYPTO);
                error = ENOBUFS;
                goto bad;
        }

    {
        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);
                pool_cache_put(esp_tdb_crypto_pool_cache, tc);
                crypto_freereq(crp);
                ESP_STATINC(ESP_STAT_NOTDB);
                error = ENOENT;
                goto bad;
        }
        KEY_SP_REF(isr->sp);
        KEY_SA_REF(sav);
        pserialize_read_exit(s);
    }

        /* Callback parameters */
        tc->tc_isr = isr;
        tc->tc_spi = sav->spi;
        tc->tc_dst = saidx->dst;
        tc->tc_proto = saidx->proto;
        tc->tc_flags = flags;
        tc->tc_sav = sav;

        /* 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 = esp_output_cb;
        crp->crp_opaque = tc;
        crp->crp_sid = sav->tdb_cryptoid;

        if (esph) {
                /* Authentication descriptor. */
                crda->crd_skip = skip;
                if (espx->type == CRYPTO_AES_GCM_16)
                        crda->crd_len = hlen - sav->ivlen;
                else
                        crda->crd_len = m->m_pkthdr.len - (skip + alen);
                crda->crd_inject = m->m_pkthdr.len - alen;

                /* Authentication operation. */
                crda->crd_alg = esph->type;
                if (espx->type == CRYPTO_AES_GCM_16 ||
                    espx->type == CRYPTO_AES_GMAC) {
                        crda->crd_key = _KEYBUF(sav->key_enc);
                        crda->crd_klen = _KEYBITS(sav->key_enc);
                } else {
                        crda->crd_key = _KEYBUF(sav->key_auth);
                        crda->crd_klen = _KEYBITS(sav->key_auth);
                }
        }

        crypto_dispatch(crp);
        return 0;

bad:
        m_freem(m);
        return error;
}

/*
 * ESP output callback from the crypto driver.
 */
static void
esp_output_cb(struct cryptop *crp)
{
        struct tdb_crypto *tc;
        const struct ipsecrequest *isr;
        struct secasvar *sav;
        struct mbuf *m;
        int flags;
        IPSEC_DECLARE_LOCK_VARIABLE;

        KASSERT(crp->crp_opaque != NULL);
        tc = crp->crp_opaque;
        m = crp->crp_buf;

        IPSEC_ACQUIRE_GLOBAL_LOCKS();

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

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

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

        ESP_STATINC(ESP_STAT_HIST + esp_stats[sav->alg_enc]);
        if (sav->tdb_authalgxform != NULL)
                AH_STATINC(AH_STAT_HIST + ah_stats[sav->alg_auth]);

        flags = tc->tc_flags;
        /* Release crypto descriptors. */
        pool_cache_put(esp_tdb_crypto_pool_cache, tc);
        crypto_freereq(crp);

#ifdef IPSEC_DEBUG
        /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
        if (ipsec_integrity) {
                static unsigned char ipseczeroes[AH_ALEN_MAX];
                const struct auth_hash *esph;

                /*
                 * Corrupt HMAC if we want to test integrity verification of
                 * the other side.
                 */
                esph = sav->tdb_authalgxform;
                if (esph !=  NULL) {
                        m_copyback(m, m->m_pkthdr.len - esph->authsize,
                            esph->authsize, 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);
        pool_cache_put(esp_tdb_crypto_pool_cache, tc);
        crypto_freereq(crp);
}

static struct xformsw esp_xformsw = {
        .xf_type        = XF_ESP,
        .xf_flags       = XFT_CONF|XFT_AUTH,
        .xf_name        = "IPsec ESP",
        .xf_init        = esp_init,
        .xf_zeroize     = esp_zeroize,
        .xf_input       = esp_input,
        .xf_output      = esp_output,
        .xf_next        = NULL,
};

void
esp_attach(void)
{

        espstat_percpu = percpu_alloc(sizeof(uint64_t) * ESP_NSTATS);

        extern int ah_max_authsize;
        KASSERT(ah_max_authsize != 0);
        esp_pool_item_size = sizeof(struct tdb_crypto) + ah_max_authsize;
        esp_tdb_crypto_pool_cache = pool_cache_init(esp_pool_item_size,
            coherency_unit, 0, 0, "esp_tdb_crypto", NULL, IPL_SOFTNET,
            NULL, NULL, NULL);

#define MAXIV(xform)                                    \
        if (xform.ivsize > esp_max_ivlen)               \
                esp_max_ivlen = xform.ivsize            \

        esp_max_ivlen = 0;
        MAXIV(enc_xform_des);           /* SADB_EALG_DESCBC */
        MAXIV(enc_xform_3des);          /* SADB_EALG_3DESCBC */
        MAXIV(enc_xform_aes);           /* SADB_X_EALG_AES */
        MAXIV(enc_xform_blf);           /* SADB_X_EALG_BLOWFISHCBC */
        MAXIV(enc_xform_cast5);         /* SADB_X_EALG_CAST128CBC */
        MAXIV(enc_xform_skipjack);      /* SADB_X_EALG_SKIPJACK */
        MAXIV(enc_xform_camellia);      /* SADB_X_EALG_CAMELLIACBC */
        MAXIV(enc_xform_aes_ctr);       /* SADB_X_EALG_AESCTR */
        MAXIV(enc_xform_null);          /* SADB_EALG_NULL */

        xform_register(&esp_xformsw);
#undef MAXIV
}