/*      $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 "opt_inet.h"
#include "opt_inet6.h"
#include "opt_ipsec.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/random.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/mutex.h>
#include <machine/atomic.h>

#include <net/if.h>
#include <net/vnet.h>

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

#include <netipsec/ipsec.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>
#include <netinet6/ip6_ecn.h>
#endif

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

#include <opencrypto/cryptodev.h>
#include <opencrypto/xform.h>

#define SPI_SIZE        4

VNET_DEFINE(int, esp_enable) = 1;
VNET_DEFINE(int, esp_ctr_compatibility) = 1;
VNET_PCPUSTAT_DEFINE(struct espstat, espstat);
VNET_PCPUSTAT_SYSINIT(espstat);

#ifdef VIMAGE
VNET_PCPUSTAT_SYSUNINIT(espstat);
#endif /* VIMAGE */

SYSCTL_DECL(_net_inet_esp);
SYSCTL_INT(_net_inet_esp, OID_AUTO, esp_enable,
        CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_enable), 0, "");
SYSCTL_INT(_net_inet_esp, OID_AUTO, ctr_compatibility,
    CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(esp_ctr_compatibility), 0,
    "Align AES-CTR encrypted transmitted frames to blocksize");
SYSCTL_VNET_PCPUSTAT(_net_inet_esp, IPSECCTL_STATS, stats,
    struct espstat, espstat,
    "ESP statistics (struct espstat, netipsec/esp_var.h");

static MALLOC_DEFINE(M_ESP, "esp", "IPsec ESP");

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

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

        if (sav != NULL) {
                /*XXX not right for null algorithm--does it matter??*/
                IPSEC_ASSERT(sav->tdb_encalgxform != NULL,
                        ("SA with null xform"));
                if (sav->flags & SADB_X_EXT_OLD)
                        size = sizeof (struct esp);
                else
                        size = sizeof (struct newesp);
                size += sav->tdb_encalgxform->blocksize + 9;
                /*XXX need alg check???*/
                if (sav->tdb_authalgxform != NULL && sav->replay)
                        size += ah_hdrsiz(sav);
        } else {
                /*
                 *   base header size
                 * + max iv length for CBC mode
                 * + max pad length
                 * + sizeof (pad length field)
                 * + sizeof (next header field)
                 * + max icv supported.
                 */
                size = sizeof (struct newesp) + EALG_MAX_BLOCK_LEN + 9 + 16;
        }
        return size;
}

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

        txform = enc_algorithm_lookup(sav->alg_enc);
        if (txform == NULL) {
                DPRINTF(("%s: unsupported encryption algorithm %d\n",
                        __func__, sav->alg_enc));
                return EINVAL;
        }
        if (sav->key_enc == NULL) {
                DPRINTF(("%s: no encoding key for %s algorithm\n",
                         __func__, txform->name));
                return EINVAL;
        }
        if ((sav->flags & (SADB_X_EXT_OLD | SADB_X_EXT_IV4B)) ==
            SADB_X_EXT_IV4B) {
                DPRINTF(("%s: 4-byte IV not supported with protocol\n",
                        __func__));
                return EINVAL;
        }

        /* subtract off the salt, RFC4106, 8.1 and RFC3686, 5.1 */
        keylen = _KEYLEN(sav->key_enc) - SAV_ISCTRORGCM(sav) * 4 -
            SAV_ISCHACHA(sav) * 4;
        if (txform->minkey > keylen || keylen > txform->maxkey) {
                DPRINTF(("%s: invalid key length %u, must be in the range "
                        "[%u..%u] for algorithm %s\n", __func__,
                        keylen, txform->minkey, txform->maxkey,
                        txform->name));
                return EINVAL;
        }

        if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav))
                sav->ivlen = 8; /* RFC4106 3.1 and RFC3686 3.1 */
        else
                sav->ivlen = txform->ivsize;

        memset(&csp, 0, sizeof(csp));

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

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

        /*
         * Whenever AES-GCM is used for encryption, one
         * of the AES authentication algorithms is chosen
         * as well, based on the key size.
         */
        if (sav->alg_enc == SADB_X_EALG_AESGCM16) {
                switch (keylen) {
                case AES_128_GMAC_KEY_LEN:
                        sav->alg_auth = SADB_X_AALG_AES128GMAC;
                        sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_128;
                        break;
                case AES_192_GMAC_KEY_LEN:
                        sav->alg_auth = SADB_X_AALG_AES192GMAC;
                        sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_192;
                        break;
                case AES_256_GMAC_KEY_LEN:
                        sav->alg_auth = SADB_X_AALG_AES256GMAC;
                        sav->tdb_authalgxform = &auth_hash_nist_gmac_aes_256;
                        break;
                default:
                        DPRINTF(("%s: invalid key length %u"
                                 "for algorithm %s\n", __func__,
                                 keylen, txform->name));
                        return EINVAL;
                }
                csp.csp_mode = CSP_MODE_AEAD;
                if (sav->flags & SADB_X_SAFLAGS_ESN)
                        csp.csp_flags |= CSP_F_SEPARATE_AAD;
        } else if (sav->alg_enc == SADB_X_EALG_CHACHA20POLY1305) {
                sav->alg_auth = SADB_X_AALG_CHACHA20POLY1305;
                sav->tdb_authalgxform = &auth_hash_poly1305;
                csp.csp_mode = CSP_MODE_AEAD;
                if (sav->flags & SADB_X_SAFLAGS_ESN)
                        csp.csp_flags |= CSP_F_SEPARATE_AAD;
        } else if (sav->alg_auth != 0) {
                csp.csp_mode = CSP_MODE_ETA;
                if (sav->flags & SADB_X_SAFLAGS_ESN)
                        csp.csp_flags |= CSP_F_ESN;
        } else
                csp.csp_mode = CSP_MODE_CIPHER;

        /* Initialize crypto session. */
        csp.csp_cipher_alg = sav->tdb_encalgxform->type;
        if (csp.csp_cipher_alg != CRYPTO_NULL_CBC) {
                csp.csp_cipher_key = sav->key_enc->key_data;
                csp.csp_cipher_klen = _KEYBITS(sav->key_enc) / 8 -
                    SAV_ISCTRORGCM(sav) * 4 - SAV_ISCHACHA(sav) * 4;
        };
        csp.csp_ivlen = txform->ivsize;

        error = crypto_newsession(&sav->tdb_cryptoid, &csp, V_crypto_support);
        return error;
}

static void
esp_cleanup(struct secasvar *sav)
{

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

/*
 * ESP input processing, called (eventually) through the protocol switch.
 */
static int
esp_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
{
        IPSEC_DEBUG_DECLARE(char buf[128]);
        const struct auth_hash *esph;
        const struct enc_xform *espx;
        struct xform_data *xd;
        struct cryptop *crp;
        struct newesp *esp;
        uint8_t *ivp;
        crypto_session_t cryptoid;
        int alen, error, hlen, plen;
        uint32_t seqh;
        const struct crypto_session_params *csp;

        SECASVAR_RLOCK_TRACKER;

        IPSEC_ASSERT(sav != NULL, ("null SA"));
        IPSEC_ASSERT(sav->tdb_encalgxform != NULL, ("null encoding xform"));

        error = EINVAL;
        /* Valid IP Packet length ? */
        if ( (skip&3) || (m->m_pkthdr.len&3) ){
                DPRINTF(("%s: misaligned packet, skip %u pkt len %u",
                                __func__, skip, m->m_pkthdr.len));
                ESPSTAT_INC(esps_badilen);
                goto bad;
        }

        if (m->m_len < skip + sizeof(*esp)) {
                m = m_pullup(m, skip + sizeof(*esp));
                if (m == NULL) {
                        DPRINTF(("%s: cannot pullup header\n", __func__));
                        ESPSTAT_INC(esps_hdrops);       /*XXX*/
                        error = ENOBUFS;
                        goto bad;
                }
        }
        esp = (struct newesp *)(mtod(m, caddr_t) + skip);

        esph = sav->tdb_authalgxform;
        espx = sav->tdb_encalgxform;

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

        alen = xform_ah_authsize(esph);

        /*
         * Verify payload length is multiple of encryption algorithm
         * block size.
         *
         * NB: This works for the null algorithm because the blocksize
         *     is 4 and all packets must be 4-byte aligned regardless
         *     of the algorithm.
         */
        plen = m->m_pkthdr.len - (skip + hlen + alen);
        if ((plen & (espx->blocksize - 1)) || (plen <= 0)) {
                DPRINTF(("%s: payload of %d octets not a multiple of %d octets,"
                    "  SA %s/%08lx\n", __func__, plen, espx->blocksize,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long)ntohl(sav->spi)));
                ESPSTAT_INC(esps_badilen);
                goto bad;
        }

        /*
         * Check sequence number.
         */
        SECASVAR_RLOCK(sav);
        if (esph != NULL && sav->replay != NULL && sav->replay->wsize != 0) {
                if (ipsec_chkreplay(ntohl(esp->esp_seq), &seqh, sav) == 0) {
                        SECASVAR_RUNLOCK(sav);
                        DPRINTF(("%s: packet replay check for %s\n", __func__,
                            ipsec_sa2str(sav, buf, sizeof(buf))));
                        ESPSTAT_INC(esps_replay);
                        error = EACCES;
                        goto bad;
                }
                seqh = htonl(seqh);
        }
        cryptoid = sav->tdb_cryptoid;
        SECASVAR_RUNLOCK(sav);

        /* Update the counters */
        ESPSTAT_ADD(esps_ibytes, m->m_pkthdr.len - (skip + hlen + alen));

        /* Get crypto descriptors */
        crp = crypto_getreq(cryptoid, M_NOWAIT);
        if (crp == NULL) {
                DPRINTF(("%s: failed to acquire crypto descriptors\n",
                        __func__));
                ESPSTAT_INC(esps_crypto);
                error = ENOBUFS;
                goto bad;
        }

        /* Get IPsec-specific opaque pointer */
        xd = malloc(sizeof(*xd), M_ESP, M_NOWAIT | M_ZERO);
        if (xd == NULL) {
                DPRINTF(("%s: failed to allocate xform_data\n", __func__));
                goto xd_fail;
        }

        if (esph != NULL) {
                crp->crp_op = CRYPTO_OP_VERIFY_DIGEST;
                if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav))
                        crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */
                else
                        crp->crp_aad_length = hlen;

                csp = crypto_get_params(crp->crp_session);
                if ((csp->csp_flags & CSP_F_SEPARATE_AAD) &&
                    (sav->replay != NULL) && (sav->replay->wsize != 0)) {
                        int aad_skip;

                        crp->crp_aad_length += sizeof(seqh);
                        crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT);
                        if (crp->crp_aad == NULL) {
                                DPRINTF(("%s: failed to allocate xform_data\n",
                                         __func__));
                                goto crp_aad_fail;
                        }

                        /* SPI */
                        m_copydata(m, skip, SPI_SIZE, crp->crp_aad);
                        aad_skip = SPI_SIZE;

                        /* ESN */
                        bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh));
                        aad_skip += sizeof(seqh);

                        /* Rest of aad */
                        if (crp->crp_aad_length - aad_skip > 0)
                                m_copydata(m, skip + SPI_SIZE,
                                           crp->crp_aad_length - aad_skip,
                                           (char *)crp->crp_aad + aad_skip);
                } else
                        crp->crp_aad_start = skip;

                if (csp->csp_flags & CSP_F_ESN &&
                           sav->replay != NULL && sav->replay->wsize != 0)
                        memcpy(crp->crp_esn, &seqh, sizeof(seqh));

                crp->crp_digest_start = m->m_pkthdr.len - alen;
        }

        /* Crypto operation descriptor */
        crp->crp_flags = CRYPTO_F_CBIFSYNC;
        crypto_use_mbuf(crp, m);
        crp->crp_callback = esp_input_cb;
        crp->crp_opaque = xd;

        /* These are passed as-is to the callback */
        xd->sav = sav;
        xd->protoff = protoff;
        xd->skip = skip;
        xd->cryptoid = cryptoid;
        xd->vnet = curvnet;

        /* Decryption descriptor */
        crp->crp_op |= CRYPTO_OP_DECRYPT;
        crp->crp_payload_start = skip + hlen;
        crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen);

        /* Generate or read cipher IV. */
        if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) {
                ivp = &crp->crp_iv[0];

                /*
                 * AES-GCM and AES-CTR use similar cipher IV formats
                 * defined in RFC 4106 section 4 and RFC 3686 section
                 * 4, respectively.
                 *
                 * The first 4 bytes of the cipher IV contain an
                 * implicit salt, or nonce, obtained from the last 4
                 * bytes of the encryption key.  The next 8 bytes hold
                 * an explicit IV unique to each packet.  This
                 * explicit IV is used as the ESP IV for the packet.
                 * The last 4 bytes hold a big-endian block counter
                 * incremented for each block.  For AES-GCM, the block
                 * counter's initial value is defined as part of the
                 * algorithm.  For AES-CTR, the block counter's
                 * initial value for each packet is defined as 1 by
                 * RFC 3686.
                 *
                 * ------------------------------------------
                 * | Salt | Explicit ESP IV | Block Counter |
                 * ------------------------------------------
                 *  4 bytes     8 bytes          4 bytes
                 */
                memcpy(ivp, sav->key_enc->key_data +
                    _KEYLEN(sav->key_enc) - 4, 4);
                m_copydata(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]);
                if (SAV_ISCTR(sav)) {
                        be32enc(&ivp[sav->ivlen + 4], 1);
                }
                crp->crp_flags |= CRYPTO_F_IV_SEPARATE;
        } else if (sav->ivlen != 0)
                crp->crp_iv_start = skip + hlen - sav->ivlen;

        if (V_async_crypto)
                return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
        else
                return (crypto_dispatch(crp));

crp_aad_fail:
        free(xd, M_ESP);
xd_fail:
        crypto_freereq(crp);
        ESPSTAT_INC(esps_crypto);
        error = ENOBUFS;
bad:
        m_freem(m);
        key_freesav(&sav);
        return (error);
}

/*
 * ESP input callback from the crypto driver.
 */
static int
esp_input_cb(struct cryptop *crp)
{
        IPSEC_DEBUG_DECLARE(char buf[128]);
        struct rm_priotracker sahtree_tracker;
        uint8_t lastthree[3];
        const struct auth_hash *esph;
        struct mbuf *m;
        struct xform_data *xd;
        struct secasvar *sav;
        struct secasindex *saidx;
        crypto_session_t cryptoid;
        int hlen, skip, protoff, error, alen;

        SECASVAR_RLOCK_TRACKER;

        m = crp->crp_buf.cb_mbuf;
        xd = crp->crp_opaque;
        CURVNET_SET(xd->vnet);
        sav = xd->sav;
        ipsec_sahtree_rlock(&sahtree_tracker);
        if (sav->state >= SADB_SASTATE_DEAD) {
                /* saidx is freed */
                DPRINTF(("%s: dead SA %p spi %#x\n", __func__, sav, sav->spi));
                ESPSTAT_INC(esps_notdb);
                error = ESRCH;
                goto bad;
        }
        skip = xd->skip;
        protoff = xd->protoff;
        cryptoid = xd->cryptoid;
        saidx = &sav->sah->saidx;
        esph = sav->tdb_authalgxform;

        /* Check for crypto errors */
        if (crp->crp_etype) {
                if (crp->crp_etype == EAGAIN) {
                        /* Reset the session ID */
                        if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
                                crypto_freesession(cryptoid);
                        xd->cryptoid = crp->crp_session;
                        ipsec_sahtree_runlock(&sahtree_tracker);
                        CURVNET_RESTORE();
                        return (crypto_dispatch(crp));
                }

                /* EBADMSG indicates authentication failure. */
                if (!(crp->crp_etype == EBADMSG && esph != NULL)) {
                        ESPSTAT_INC(esps_noxform);
                        DPRINTF(("%s: crypto error %d\n", __func__,
                                crp->crp_etype));
                        error = crp->crp_etype;
                        goto bad;
                }
        }

        /* Shouldn't happen... */
        if (m == NULL) {
                ESPSTAT_INC(esps_crypto);
                DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
                error = EINVAL;
                goto bad;
        }
        ESPSTAT_INC2(esps_hist, sav->alg_enc);

        /* If authentication was performed, check now. */
        if (esph != NULL) {
                alen = xform_ah_authsize(esph);
                AHSTAT_INC2(ahs_hist, sav->alg_auth);
                if (crp->crp_etype == EBADMSG) {
                        DPRINTF(("%s: authentication hash mismatch for "
                            "packet in SA %s/%08lx\n", __func__,
                            ipsec_address(&saidx->dst, buf, sizeof(buf)),
                            (u_long) ntohl(sav->spi)));
                        ESPSTAT_INC(esps_badauth);
                        error = EACCES;
                        goto bad;
                }
                m->m_flags |= M_AUTHIPDGM;
                /* Remove trailing authenticator */
                m_adj(m, -alen);
        }

        /* Release the crypto descriptors */
        free(xd, M_ESP), xd = NULL;
        free(crp->crp_aad, M_ESP), crp->crp_aad = NULL;
        crypto_freereq(crp), crp = NULL;

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

        /*
         * Update replay sequence number, if appropriate.
         */
        if (sav->replay) {
                u_int32_t seq;

                m_copydata(m, skip + offsetof(struct newesp, esp_seq),
                           sizeof (seq), (caddr_t) &seq);
                SECASVAR_RLOCK(sav);
                if (ipsec_updatereplay(ntohl(seq), sav)) {
                        SECASVAR_RUNLOCK(sav);
                        DPRINTF(("%s: packet replay check for %s\n", __func__,
                            ipsec_sa2str(sav, buf, sizeof(buf))));
                        ESPSTAT_INC(esps_replay);
                        error = EACCES;
                        goto bad;
                }
                SECASVAR_RUNLOCK(sav);
        }

        /* 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. */
        error = m_striphdr(m, skip, hlen);
        if (error) {
                ESPSTAT_INC(esps_hdrops);
                DPRINTF(("%s: bad mbuf chain, SA %s/%08lx\n", __func__,
                    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) {
                ESPSTAT_INC(esps_badilen);
                DPRINTF(("%s: invalid padding length %d for %u byte packet "
                    "in SA %s/%08lx\n", __func__, lastthree[1],
                    m->m_pkthdr.len - skip,
                    ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                error = EINVAL;
                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) {
                        ESPSTAT_INC(esps_badenc);
                        DPRINTF(("%s: decryption failed for packet in "
                            "SA %s/%08lx\n", __func__, ipsec_address(
                            &sav->sah->saidx.dst, buf, sizeof(buf)),
                            (u_long) ntohl(sav->spi)));
                        error = EINVAL;
                        goto bad;
                }
        }

        /*
         * RFC4303 2.6:
         * Silently drop packet if next header field is IPPROTO_NONE.
         */
        if (lastthree[2] == IPPROTO_NONE)
                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 (u_int8_t), lastthree + 2);

        switch (saidx->dst.sa.sa_family) {
#ifdef INET6
        case AF_INET6:
                error = ipsec6_common_input_cb(m, sav, skip, protoff,
                    &sahtree_tracker);
                break;
#endif
#ifdef INET
        case AF_INET:
                error = ipsec4_common_input_cb(m, sav, skip, protoff,
                    &sahtree_tracker);
                break;
#endif
        default:
                panic("%s: Unexpected address family: %d saidx=%p", __func__,
                    saidx->dst.sa.sa_family, saidx);
        }
        CURVNET_RESTORE();
        return error;
bad:
        ipsec_sahtree_runlock(&sahtree_tracker);
        if (sav != NULL)
                key_freesav(&sav);
        if (m != NULL)
                m_freem(m);
        if (xd != NULL)
                free(xd, M_ESP);
        if (crp != NULL) {
                free(crp->crp_aad, M_ESP);
                crypto_freereq(crp);
        }
        CURVNET_RESTORE();
        return error;
}
/*
 * ESP output routine, called by ipsec[46]_perform_request().
 */
static int
esp_output(struct mbuf *m, struct secpolicy *sp, struct secasvar *sav,
    u_int idx, int skip, int protoff)
{
        IPSEC_DEBUG_DECLARE(char buf[IPSEC_ADDRSTRLEN]);
        struct cryptop *crp;
        const struct auth_hash *esph;
        const struct enc_xform *espx;
        struct mbuf *mo = NULL;
        struct xform_data *xd;
        struct secasindex *saidx;
        unsigned char *pad;
        uint8_t *ivp;
        uint64_t cntr;
        crypto_session_t cryptoid;
        int hlen, rlen, padding, blks, alen, i, roff;
        int error, maxpacketsize;
        uint8_t prot;
        uint32_t seqh;
        const struct crypto_session_params *csp;

        SECASVAR_RLOCK_TRACKER;

        IPSEC_ASSERT(sav != NULL, ("null SA"));
        esph = sav->tdb_authalgxform;
        espx = sav->tdb_encalgxform;
        IPSEC_ASSERT(espx != NULL, ("null encoding xform"));

        if (sav->flags & SADB_X_EXT_OLD)
                hlen = sizeof (struct esp) + sav->ivlen;
        else
                hlen = sizeof (struct newesp) + sav->ivlen;

        rlen = m->m_pkthdr.len - skip;  /* Raw payload length. */
        /*
         * RFC4303 2.4 Requires 4 byte alignment.
         * Old versions of FreeBSD can't decrypt partial blocks encrypted
         * with AES-CTR. Align payload to native_blocksize (16 bytes)
         * in order to preserve compatibility.
         */
        if (SAV_ISCTR(sav) && V_esp_ctr_compatibility)
                blks = MAX(4, espx->native_blocksize);  /* Cipher blocksize */
        else
                blks = MAX(4, espx->blocksize);

        /* XXX clamp padding length a la KAME??? */
        padding = ((blks - ((rlen + 2) % blks)) % blks) + 2;

        alen = xform_ah_authsize(esph);

        ESPSTAT_INC(esps_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 /* INET */
#ifdef INET6
        case AF_INET6:
                maxpacketsize = IPV6_MAXPACKET;
                break;
#endif /* INET6 */
        default:
                DPRINTF(("%s: unknown/unsupported protocol "
                    "family %d, SA %s/%08lx\n", __func__,
                    saidx->dst.sa.sa_family, ipsec_address(&saidx->dst,
                        buf, sizeof(buf)), (u_long) ntohl(sav->spi)));
                ESPSTAT_INC(esps_nopf);
                error = EPFNOSUPPORT;
                goto bad;
        }
        /*
        DPRINTF(("%s: skip %d hlen %d rlen %d padding %d alen %d blksd %d\n",
                __func__, skip, hlen, rlen, padding, alen, blks)); */
        if (skip + hlen + rlen + padding + alen > maxpacketsize) {
                DPRINTF(("%s: packet in SA %s/%08lx got too big "
                    "(len %u, max len %u)\n", __func__,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi),
                    skip + hlen + rlen + padding + alen, maxpacketsize));
                ESPSTAT_INC(esps_toobig);
                error = EMSGSIZE;
                goto bad;
        }

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

        m = m_unshare(m, M_NOWAIT);
        if (m == NULL) {
                DPRINTF(("%s: cannot clone mbuf chain, SA %s/%08lx\n", __func__,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                ESPSTAT_INC(esps_hdrops);
                error = ENOBUFS;
                goto bad;
        }

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

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

                SECREPLAY_LOCK(sav->replay);
#ifdef REGRESSION
                /* Emulate replay attack when ipsec_replay is TRUE. */
                if (!V_ipsec_replay)
#endif
                        sav->replay->count++;
                replay = htonl((uint32_t)sav->replay->count);

                bcopy((caddr_t) &replay, mtod(mo, caddr_t) + roff +
                    sizeof(uint32_t), sizeof(uint32_t));

                seqh = htonl((uint32_t)(sav->replay->count >> IPSEC_SEQH_SHIFT));
                SECREPLAY_UNLOCK(sav->replay);
        }
        cryptoid = sav->tdb_cryptoid;
        if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav))
                cntr = sav->cntr++;
        SECASVAR_RUNLOCK(sav);

        /*
         * Add padding -- better to do it ourselves than use the crypto engine,
         * although if/when we support compression, we'd have to do that.
         */
        pad = (u_char *) m_pad(m, padding + alen);
        if (pad == NULL) {
                DPRINTF(("%s: m_pad failed for SA %s/%08lx\n", __func__,
                    ipsec_address(&saidx->dst, buf, sizeof(buf)),
                    (u_long) ntohl(sav->spi)));
                m = NULL;               /* NB: free'd by m_pad */
                error = ENOBUFS;
                goto bad;
        }

        /*
         * Add padding: random, zero, or self-describing.
         * XXX catch unexpected setting
         */
        switch (sav->flags & SADB_X_EXT_PMASK) {
        case SADB_X_EXT_PRAND:
                arc4random_buf(pad, padding - 2);
                break;
        case SADB_X_EXT_PZERO:
                bzero(pad, padding - 2);
                break;
        case SADB_X_EXT_PSEQ:
                for (i = 0; i < padding - 2; i++)
                        pad[i] = i+1;
                break;
        }

        /* Fix padding length and Next Protocol in padding itself. */
        pad[padding - 2] = padding - 2;
        m_copydata(m, protoff, sizeof(u_int8_t), pad + padding - 1);

        /* Fix Next Protocol in IPv4/IPv6 header. */
        prot = IPPROTO_ESP;
        m_copyback(m, protoff, sizeof(u_int8_t), (u_char *) &prot);

        /* Get crypto descriptor. */
        crp = crypto_getreq(cryptoid, M_NOWAIT);
        if (crp == NULL) {
                DPRINTF(("%s: failed to acquire crypto descriptor\n",
                        __func__));
                ESPSTAT_INC(esps_crypto);
                error = ENOBUFS;
                goto bad;
        }

        /* IPsec-specific opaque crypto info. */
        xd = malloc(sizeof(struct xform_data), M_ESP, M_NOWAIT | M_ZERO);
        if (xd == NULL) {
                DPRINTF(("%s: failed to allocate xform_data\n", __func__));
                goto xd_fail;
        }

        /* Encryption descriptor. */
        crp->crp_payload_start = skip + hlen;
        crp->crp_payload_length = m->m_pkthdr.len - (skip + hlen + alen);
        crp->crp_op = CRYPTO_OP_ENCRYPT;

        /* Generate cipher and ESP IVs. */
        ivp = &crp->crp_iv[0];
        if (SAV_ISCTRORGCM(sav) || SAV_ISCHACHA(sav)) {
                /*
                 * See comment in esp_input() for details on the
                 * cipher IV.  A simple per-SA counter stored in
                 * 'cntr' is used as the explicit ESP IV.
                 */
                memcpy(ivp, sav->key_enc->key_data +
                    _KEYLEN(sav->key_enc) - 4, 4);
                be64enc(&ivp[4], cntr);
                if (SAV_ISCTR(sav)) {
                        be32enc(&ivp[sav->ivlen + 4], 1);
                }
                m_copyback(m, skip + hlen - sav->ivlen, sav->ivlen, &ivp[4]);
                crp->crp_flags |= CRYPTO_F_IV_SEPARATE;
        } else if (sav->ivlen != 0) {
                arc4rand(ivp, sav->ivlen, 0);
                crp->crp_iv_start = skip + hlen - sav->ivlen;
                m_copyback(m, crp->crp_iv_start, sav->ivlen, ivp);
        }

        /* Callback parameters */
        xd->sp = sp;
        xd->sav = sav;
        xd->idx = idx;
        xd->cryptoid = cryptoid;
        xd->vnet = curvnet;

        /* Crypto operation descriptor. */
        crp->crp_flags |= CRYPTO_F_CBIFSYNC;
        crypto_use_mbuf(crp, m);
        crp->crp_callback = esp_output_cb;
        crp->crp_opaque = xd;

        if (esph) {
                /* Authentication descriptor. */
                crp->crp_op |= CRYPTO_OP_COMPUTE_DIGEST;
                if (SAV_ISGCM(sav) || SAV_ISCHACHA(sav))
                        crp->crp_aad_length = 8; /* RFC4106 5, SPI + SN */
                else
                        crp->crp_aad_length = hlen;

                csp = crypto_get_params(crp->crp_session);
                if (csp->csp_flags & CSP_F_SEPARATE_AAD &&
                    sav->replay != NULL) {
                        int aad_skip;

                        crp->crp_aad_length += sizeof(seqh);
                        crp->crp_aad = malloc(crp->crp_aad_length, M_ESP, M_NOWAIT);
                        if (crp->crp_aad == NULL) {
                                DPRINTF(("%s: failed to allocate xform_data\n",
                                         __func__));
                                goto crp_aad_fail;
                        }

                        /* SPI */
                        m_copydata(m, skip, SPI_SIZE, crp->crp_aad);
                        aad_skip = SPI_SIZE;

                        /* ESN */
                        bcopy(&seqh, (char *)crp->crp_aad + aad_skip, sizeof(seqh));
                        aad_skip += sizeof(seqh);

                        /* Rest of aad */
                        if (crp->crp_aad_length - aad_skip > 0)
                                m_copydata(m, skip + SPI_SIZE,
                                           crp->crp_aad_length - aad_skip,
                                           (char *)crp->crp_aad + aad_skip);
                } else
                        crp->crp_aad_start = skip;

                if (csp->csp_flags & CSP_F_ESN && sav->replay != NULL)
                        memcpy(crp->crp_esn, &seqh, sizeof(seqh));

                crp->crp_digest_start = m->m_pkthdr.len - alen;
        }

        if (V_async_crypto)
                return (crypto_dispatch_async(crp, CRYPTO_ASYNC_ORDERED));
        else
                return (crypto_dispatch(crp));

crp_aad_fail:
        free(xd, M_ESP);
xd_fail:
        crypto_freereq(crp);
        ESPSTAT_INC(esps_crypto);
        error = ENOBUFS;
bad:
        if (m)
                m_freem(m);
        key_freesav(&sav);
        key_freesp(&sp);
        return (error);
}
/*
 * ESP output callback from the crypto driver.
 */
static int
esp_output_cb(struct cryptop *crp)
{
        struct xform_data *xd;
        struct secpolicy *sp;
        struct secasvar *sav;
        struct mbuf *m;
        crypto_session_t cryptoid;
        u_int idx;
        int error;

        xd = (struct xform_data *) crp->crp_opaque;
        CURVNET_SET(xd->vnet);
        m = crp->crp_buf.cb_mbuf;
        sp = xd->sp;
        sav = xd->sav;
        idx = xd->idx;
        cryptoid = xd->cryptoid;

        /* Check for crypto errors. */
        if (crp->crp_etype) {
                if (crp->crp_etype == EAGAIN) {
                        /* Reset the session ID */
                        if (ipsec_updateid(sav, &crp->crp_session, &cryptoid) != 0)
                                crypto_freesession(cryptoid);
                        xd->cryptoid = crp->crp_session;
                        CURVNET_RESTORE();
                        return (crypto_dispatch(crp));
                }
                ESPSTAT_INC(esps_noxform);
                DPRINTF(("%s: crypto error %d\n", __func__, crp->crp_etype));
                error = crp->crp_etype;
                m_freem(m);
                goto bad;
        }

        /* Shouldn't happen... */
        if (m == NULL) {
                ESPSTAT_INC(esps_crypto);
                DPRINTF(("%s: bogus returned buffer from crypto\n", __func__));
                error = EINVAL;
                goto bad;
        }
        free(xd, M_ESP);
        free(crp->crp_aad, M_ESP);
        crypto_freereq(crp);
        ESPSTAT_INC2(esps_hist, sav->alg_enc);
        if (sav->tdb_authalgxform != NULL)
                AHSTAT_INC2(ahs_hist, sav->alg_auth);

#ifdef REGRESSION
        /* Emulate man-in-the-middle attack when ipsec_integrity is TRUE. */
        if (V_ipsec_integrity) {
                static unsigned char ipseczeroes[AH_HMAC_MAXHASHLEN];
                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) {
                        int alen;

                        alen = xform_ah_authsize(esph);
                        m_copyback(m, m->m_pkthdr.len - alen,
                            alen, ipseczeroes);
                }
        }
#endif

        /* NB: m is reclaimed by ipsec_process_done. */
        error = ipsec_process_done(m, sp, sav, idx);
        CURVNET_RESTORE();
        return (error);
bad:
        free(xd, M_ESP);
        free(crp->crp_aad, M_ESP);
        crypto_freereq(crp);
        key_freesav(&sav);
        key_freesp(&sp);
        CURVNET_RESTORE();
        return (error);
}

static struct xformsw esp_xformsw = {
        .xf_type =      XF_ESP,
        .xf_name =      "IPsec ESP",
        .xf_init =      esp_init,
        .xf_cleanup =   esp_cleanup,
        .xf_input =     esp_input,
        .xf_output =    esp_output,
};

SYSINIT(esp_xform_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
    xform_attach, &esp_xformsw);
SYSUNINIT(esp_xform_uninit, SI_SUB_PROTO_DOMAIN, SI_ORDER_MIDDLE,
    xform_detach, &esp_xformsw);