e_devcrypto.c

/*
 * Copyright 2017-2023 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/* We need to use some deprecated APIs */
#define OPENSSL_SUPPRESS_DEPRECATED

#include "internal/e_os.h"
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <assert.h>

#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include <openssl/engine.h>
#include <openssl/objects.h>
#include "crypto/cryptodev.h"
#include "internal/nelem.h"

/* #define ENGINE_DEVCRYPTO_DEBUG */

#if CRYPTO_ALGORITHM_MIN < CRYPTO_ALGORITHM_MAX
#define CHECK_BSD_STYLE_MACROS
#endif

#define engine_devcrypto_id "devcrypto"

/*
 * Use session2_op on FreeBSD which permits requesting specific
 * drivers or classes of drivers at session creation time.
 */
#ifdef CIOCGSESSION2
typedef struct session2_op session_op_t;
#else
typedef struct session_op session_op_t;
#endif

/*
 * ONE global file descriptor for all sessions.  This allows operations
 * such as digest session data copying (see digest_copy()), but is also
 * saner...  why re-open /dev/crypto for every session?
 */
static int cfd = -1;
#define DEVCRYPTO_REQUIRE_ACCELERATED 0 /* require confirmation of acceleration */
#define DEVCRYPTO_USE_SOFTWARE 1 /* allow software drivers */
#define DEVCRYPTO_REJECT_SOFTWARE 2 /* only disallow confirmed software drivers */

#define DEVCRYPTO_DEFAULT_USE_SOFTDRIVERS DEVCRYPTO_REJECT_SOFTWARE
static int use_softdrivers = DEVCRYPTO_DEFAULT_USE_SOFTDRIVERS;

/*
 * cipher/digest status & acceleration definitions
 * Make sure the defaults are set to 0
 */
struct driver_info_st {
    enum devcrypto_status_t {
        DEVCRYPTO_STATUS_FAILURE = -3, /* unusable for other reason */
        DEVCRYPTO_STATUS_NO_CIOCCPHASH = -2, /* hash state copy not supported */
        DEVCRYPTO_STATUS_NO_CIOCGSESSION = -1, /* session open failed */
        DEVCRYPTO_STATUS_UNKNOWN = 0, /* not tested yet */
        DEVCRYPTO_STATUS_USABLE = 1 /* algo can be used */
    } status;

    enum devcrypto_accelerated_t {
        DEVCRYPTO_NOT_ACCELERATED = -1, /* software implemented */
        DEVCRYPTO_ACCELERATION_UNKNOWN = 0, /* acceleration support unknown */
        DEVCRYPTO_ACCELERATED = 1 /* hardware accelerated */
    } accelerated;

    char *driver_name;
};

#ifdef OPENSSL_NO_DYNAMIC_ENGINE
void engine_load_devcrypto_int(void);
#endif

static int clean_devcrypto_session(session_op_t *sess)
{
    if (ioctl(cfd, CIOCFSESSION, &sess->ses) < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }
    memset(sess, 0, sizeof(*sess));
    return 1;
}

/******************************************************************************
 *
 * Ciphers
 *
 * Because they all do the same basic operation, we have only one set of
 * method functions for them all to share, and a mapping table between
 * NIDs and cryptodev IDs, with all the necessary size data.
 *
 *****/

struct cipher_ctx {
    session_op_t sess;
    int op; /* COP_ENCRYPT or COP_DECRYPT */
    unsigned long mode; /* EVP_CIPH_*_MODE */

    /* to handle ctr mode being a stream cipher */
    unsigned char partial[EVP_MAX_BLOCK_LENGTH];
    unsigned int blocksize, num;
};

static const struct cipher_data_st {
    int nid;
    int blocksize;
    int keylen;
    int ivlen;
    int flags;
    int devcryptoid;
} cipher_data[] = {
#ifndef OPENSSL_NO_DES
    { NID_des_cbc, 8, 8, 8, EVP_CIPH_CBC_MODE, CRYPTO_DES_CBC },
    { NID_des_ede3_cbc, 8, 24, 8, EVP_CIPH_CBC_MODE, CRYPTO_3DES_CBC },
#endif
#ifndef OPENSSL_NO_BF
    { NID_bf_cbc, 8, 16, 8, EVP_CIPH_CBC_MODE, CRYPTO_BLF_CBC },
#endif
#ifndef OPENSSL_NO_CAST
    { NID_cast5_cbc, 8, 16, 8, EVP_CIPH_CBC_MODE, CRYPTO_CAST_CBC },
#endif
    { NID_aes_128_cbc, 16, 128 / 8, 16, EVP_CIPH_CBC_MODE, CRYPTO_AES_CBC },
    { NID_aes_192_cbc, 16, 192 / 8, 16, EVP_CIPH_CBC_MODE, CRYPTO_AES_CBC },
    { NID_aes_256_cbc, 16, 256 / 8, 16, EVP_CIPH_CBC_MODE, CRYPTO_AES_CBC },
#ifndef OPENSSL_NO_RC4
    { NID_rc4, 1, 16, 0, EVP_CIPH_STREAM_CIPHER, CRYPTO_ARC4 },
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_AES_CTR)
    { NID_aes_128_ctr, 16, 128 / 8, 16, EVP_CIPH_CTR_MODE, CRYPTO_AES_CTR },
    { NID_aes_192_ctr, 16, 192 / 8, 16, EVP_CIPH_CTR_MODE, CRYPTO_AES_CTR },
    { NID_aes_256_ctr, 16, 256 / 8, 16, EVP_CIPH_CTR_MODE, CRYPTO_AES_CTR },
#endif
#if 0 /* Not yet supported */
    { NID_aes_128_xts, 16, 128 / 8 * 2, 16, EVP_CIPH_XTS_MODE, CRYPTO_AES_XTS },
    { NID_aes_256_xts, 16, 256 / 8 * 2, 16, EVP_CIPH_XTS_MODE, CRYPTO_AES_XTS },
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_AES_ECB)
    { NID_aes_128_ecb, 16, 128 / 8, 0, EVP_CIPH_ECB_MODE, CRYPTO_AES_ECB },
    { NID_aes_192_ecb, 16, 192 / 8, 0, EVP_CIPH_ECB_MODE, CRYPTO_AES_ECB },
    { NID_aes_256_ecb, 16, 256 / 8, 0, EVP_CIPH_ECB_MODE, CRYPTO_AES_ECB },
#endif
#if 0 /* Not yet supported */
    { NID_aes_128_gcm, 16, 128 / 8, 16, EVP_CIPH_GCM_MODE, CRYPTO_AES_GCM },
    { NID_aes_192_gcm, 16, 192 / 8, 16, EVP_CIPH_GCM_MODE, CRYPTO_AES_GCM },
    { NID_aes_256_gcm, 16, 256 / 8, 16, EVP_CIPH_GCM_MODE, CRYPTO_AES_GCM },
#endif
#ifndef OPENSSL_NO_CAMELLIA
    { NID_camellia_128_cbc, 16, 128 / 8, 16, EVP_CIPH_CBC_MODE,
        CRYPTO_CAMELLIA_CBC },
    { NID_camellia_192_cbc, 16, 192 / 8, 16, EVP_CIPH_CBC_MODE,
        CRYPTO_CAMELLIA_CBC },
    { NID_camellia_256_cbc, 16, 256 / 8, 16, EVP_CIPH_CBC_MODE,
        CRYPTO_CAMELLIA_CBC },
#endif
};

static size_t find_cipher_data_index(int nid)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(cipher_data); i++)
        if (nid == cipher_data[i].nid)
            return i;
    return (size_t)-1;
}

static size_t get_cipher_data_index(int nid)
{
    size_t i = find_cipher_data_index(nid);

    if (i != (size_t)-1)
        return i;

    /*
     * Code further down must make sure that only NIDs in the table above
     * are used.  If any other NID reaches this function, there's a grave
     * coding error further down.
     */
    assert("Code that never should be reached" == NULL);
    return -1;
}

static const struct cipher_data_st *get_cipher_data(int nid)
{
    return &cipher_data[get_cipher_data_index(nid)];
}

/*
 * Following are the three necessary functions to map OpenSSL functionality
 * with cryptodev.
 */

static int cipher_init(EVP_CIPHER_CTX *ctx, const unsigned char *key,
    const unsigned char *iv, int enc)
{
    struct cipher_ctx *cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(ctx);
    const struct cipher_data_st *cipher_d = get_cipher_data(EVP_CIPHER_CTX_get_nid(ctx));
    int ret;

    /* cleanup a previous session */
    if (cipher_ctx->sess.ses != 0 && clean_devcrypto_session(&cipher_ctx->sess) == 0)
        return 0;

    cipher_ctx->sess.cipher = cipher_d->devcryptoid;
    cipher_ctx->sess.keylen = cipher_d->keylen;
    cipher_ctx->sess.key = (void *)key;
    cipher_ctx->op = enc ? COP_ENCRYPT : COP_DECRYPT;
    cipher_ctx->mode = cipher_d->flags & EVP_CIPH_MODE;
    cipher_ctx->blocksize = cipher_d->blocksize;
#ifdef CIOCGSESSION2
    cipher_ctx->sess.crid = (use_softdrivers == DEVCRYPTO_USE_SOFTWARE) ? CRYPTO_FLAG_SOFTWARE | CRYPTO_FLAG_HARDWARE : CRYPTO_FLAG_HARDWARE;
    ret = ioctl(cfd, CIOCGSESSION2, &cipher_ctx->sess);
#else
    ret = ioctl(cfd, CIOCGSESSION, &cipher_ctx->sess);
#endif
    if (ret < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }

    return 1;
}

static int cipher_do_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
    const unsigned char *in, size_t inl)
{
    struct cipher_ctx *cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(ctx);
    struct crypt_op cryp;
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
#if !defined(COP_FLAG_WRITE_IV)
    unsigned char saved_iv[EVP_MAX_IV_LENGTH];
    const unsigned char *ivptr;
    size_t nblocks, ivlen;
#endif

    memset(&cryp, 0, sizeof(cryp));
    cryp.ses = cipher_ctx->sess.ses;
    cryp.len = inl;
    cryp.src = (void *)in;
    cryp.dst = (void *)out;
    cryp.iv = (void *)iv;
    cryp.op = cipher_ctx->op;
#if !defined(COP_FLAG_WRITE_IV)
    cryp.flags = 0;

    ivlen = EVP_CIPHER_CTX_get_iv_length(ctx);
    if (ivlen > 0)
        switch (cipher_ctx->mode) {
        case EVP_CIPH_CBC_MODE:
            assert(inl >= ivlen);
            if (!EVP_CIPHER_CTX_is_encrypting(ctx)) {
                ivptr = in + inl - ivlen;
                memcpy(saved_iv, ivptr, ivlen);
            }
            break;

        case EVP_CIPH_CTR_MODE:
            break;

        default: /* should not happen */
            return 0;
        }
#else
    cryp.flags = COP_FLAG_WRITE_IV;
#endif

    if (ioctl(cfd, CIOCCRYPT, &cryp) < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }

#if !defined(COP_FLAG_WRITE_IV)
    if (ivlen > 0)
        switch (cipher_ctx->mode) {
        case EVP_CIPH_CBC_MODE:
            assert(inl >= ivlen);
            if (EVP_CIPHER_CTX_is_encrypting(ctx))
                ivptr = out + inl - ivlen;
            else
                ivptr = saved_iv;

            memcpy(iv, ivptr, ivlen);
            break;

        case EVP_CIPH_CTR_MODE:
            nblocks = (inl + cipher_ctx->blocksize - 1)
                / cipher_ctx->blocksize;
            do {
                ivlen--;
                nblocks += iv[ivlen];
                iv[ivlen] = (uint8_t)nblocks;
                nblocks >>= 8;
            } while (ivlen);
            break;

        default: /* should not happen */
            return 0;
        }
#endif

    return 1;
}

static int ctr_do_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
    const unsigned char *in, size_t inl)
{
    struct cipher_ctx *cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(ctx);
    size_t nblocks, len;

    /* initial partial block */
    while (cipher_ctx->num && inl) {
        (*out++) = *(in++) ^ cipher_ctx->partial[cipher_ctx->num];
        --inl;
        cipher_ctx->num = (cipher_ctx->num + 1) % cipher_ctx->blocksize;
    }

    /* full blocks */
    if (inl > cipher_ctx->blocksize) {
        nblocks = inl / cipher_ctx->blocksize;
        len = nblocks * cipher_ctx->blocksize;
        if (cipher_do_cipher(ctx, out, in, len) < 1)
            return 0;
        inl -= len;
        out += len;
        in += len;
    }

    /* final partial block */
    if (inl) {
        memset(cipher_ctx->partial, 0, cipher_ctx->blocksize);
        if (cipher_do_cipher(ctx, cipher_ctx->partial, cipher_ctx->partial,
                cipher_ctx->blocksize)
            < 1)
            return 0;
        while (inl--) {
            out[cipher_ctx->num] = in[cipher_ctx->num]
                ^ cipher_ctx->partial[cipher_ctx->num];
            cipher_ctx->num++;
        }
    }

    return 1;
}

static int cipher_ctrl(EVP_CIPHER_CTX *ctx, int type, int p1, void *p2)
{
    struct cipher_ctx *cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(ctx);
    EVP_CIPHER_CTX *to_ctx = (EVP_CIPHER_CTX *)p2;
    struct cipher_ctx *to_cipher_ctx;

    switch (type) {

    case EVP_CTRL_COPY:
        if (cipher_ctx == NULL)
            return 1;
        /* when copying the context, a new session needs to be initialized */
        to_cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(to_ctx);
        memset(&to_cipher_ctx->sess, 0, sizeof(to_cipher_ctx->sess));
        return cipher_init(to_ctx, (void *)cipher_ctx->sess.key, EVP_CIPHER_CTX_iv(ctx),
            (cipher_ctx->op == COP_ENCRYPT));

    case EVP_CTRL_INIT:
        memset(&cipher_ctx->sess, 0, sizeof(cipher_ctx->sess));
        return 1;

    default:
        break;
    }

    return -1;
}

static int cipher_cleanup(EVP_CIPHER_CTX *ctx)
{
    struct cipher_ctx *cipher_ctx = (struct cipher_ctx *)EVP_CIPHER_CTX_get_cipher_data(ctx);

    return clean_devcrypto_session(&cipher_ctx->sess);
}

/*
 * Keep tables of known nids, associated methods, selected ciphers, and driver
 * info.
 * Note that known_cipher_nids[] isn't necessarily indexed the same way as
 * cipher_data[] above, which the other tables are.
 */
static int known_cipher_nids[OSSL_NELEM(cipher_data)];
static int known_cipher_nids_amount = -1; /* -1 indicates not yet initialised */
static EVP_CIPHER *known_cipher_methods[OSSL_NELEM(cipher_data)] = {
    NULL,
};
static int selected_ciphers[OSSL_NELEM(cipher_data)];
static struct driver_info_st cipher_driver_info[OSSL_NELEM(cipher_data)];

static int devcrypto_test_cipher(size_t cipher_data_index)
{
    return (cipher_driver_info[cipher_data_index].status == DEVCRYPTO_STATUS_USABLE
        && selected_ciphers[cipher_data_index] == 1
        && (cipher_driver_info[cipher_data_index].accelerated
                == DEVCRYPTO_ACCELERATED
            || use_softdrivers == DEVCRYPTO_USE_SOFTWARE
            || (cipher_driver_info[cipher_data_index].accelerated
                    != DEVCRYPTO_NOT_ACCELERATED
                && use_softdrivers == DEVCRYPTO_REJECT_SOFTWARE)));
}

static void prepare_cipher_methods(void)
{
    size_t i;
    session_op_t sess;
    unsigned long cipher_mode;
#ifdef CIOCGSESSION2
    struct crypt_find_op fop;
    enum devcrypto_accelerated_t accelerated;
#elif defined(CIOCGSESSINFO)
    struct session_info_op siop;
#endif

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

    memset(&sess, 0, sizeof(sess));
    sess.key = (void *)"01234567890123456789012345678901234567890123456789";

    for (i = 0, known_cipher_nids_amount = 0;
        i < OSSL_NELEM(cipher_data); i++) {

        selected_ciphers[i] = 1;
        /*
         * Check that the cipher is usable
         */
        sess.cipher = cipher_data[i].devcryptoid;
        sess.keylen = cipher_data[i].keylen;
#ifdef CIOCGSESSION2
        /*
         * When using CIOCGSESSION2, first try to allocate a hardware
         * ("accelerated") session.  If that fails, fall back to
         * allocating a software session.
         */
        sess.crid = CRYPTO_FLAG_HARDWARE;
        if (ioctl(cfd, CIOCGSESSION2, &sess) == 0) {
            accelerated = DEVCRYPTO_ACCELERATED;
        } else {
            sess.crid = CRYPTO_FLAG_SOFTWARE;
            if (ioctl(cfd, CIOCGSESSION2, &sess) < 0) {
                cipher_driver_info[i].status = DEVCRYPTO_STATUS_NO_CIOCGSESSION;
                continue;
            }
            accelerated = DEVCRYPTO_NOT_ACCELERATED;
        }
#else
        if (ioctl(cfd, CIOCGSESSION, &sess) < 0) {
            cipher_driver_info[i].status = DEVCRYPTO_STATUS_NO_CIOCGSESSION;
            continue;
        }
#endif

        cipher_mode = cipher_data[i].flags & EVP_CIPH_MODE;

        if ((known_cipher_methods[i] = EVP_CIPHER_meth_new(cipher_data[i].nid,
                 cipher_mode == EVP_CIPH_CTR_MODE ? 1 : cipher_data[i].blocksize,
                 cipher_data[i].keylen))
                == NULL
            || !EVP_CIPHER_meth_set_iv_length(known_cipher_methods[i],
                cipher_data[i].ivlen)
            || !EVP_CIPHER_meth_set_flags(known_cipher_methods[i],
                cipher_data[i].flags
                    | EVP_CIPH_CUSTOM_COPY
                    | EVP_CIPH_CTRL_INIT
                    | EVP_CIPH_FLAG_DEFAULT_ASN1)
            || !EVP_CIPHER_meth_set_init(known_cipher_methods[i], cipher_init)
            || !EVP_CIPHER_meth_set_do_cipher(known_cipher_methods[i],
                cipher_mode == EVP_CIPH_CTR_MODE ? ctr_do_cipher : cipher_do_cipher)
            || !EVP_CIPHER_meth_set_ctrl(known_cipher_methods[i], cipher_ctrl)
            || !EVP_CIPHER_meth_set_cleanup(known_cipher_methods[i],
                cipher_cleanup)
            || !EVP_CIPHER_meth_set_impl_ctx_size(known_cipher_methods[i],
                sizeof(struct cipher_ctx))) {
            cipher_driver_info[i].status = DEVCRYPTO_STATUS_FAILURE;
            EVP_CIPHER_meth_free(known_cipher_methods[i]);
            known_cipher_methods[i] = NULL;
        } else {
            cipher_driver_info[i].status = DEVCRYPTO_STATUS_USABLE;
#ifdef CIOCGSESSION2
            cipher_driver_info[i].accelerated = accelerated;
            fop.crid = sess.crid;
            if (ioctl(cfd, CIOCFINDDEV, &fop) == 0) {
                cipher_driver_info[i].driver_name = OPENSSL_strndup(fop.name, sizeof(fop.name));
            }
#elif defined(CIOCGSESSINFO)
            siop.ses = sess.ses;
            if (ioctl(cfd, CIOCGSESSINFO, &siop) < 0) {
                cipher_driver_info[i].accelerated = DEVCRYPTO_ACCELERATION_UNKNOWN;
            } else {
                cipher_driver_info[i].driver_name = OPENSSL_strndup(siop.cipher_info.cra_driver_name,
                    CRYPTODEV_MAX_ALG_NAME);
                if (!(siop.flags & SIOP_FLAG_KERNEL_DRIVER_ONLY))
                    cipher_driver_info[i].accelerated = DEVCRYPTO_NOT_ACCELERATED;
                else
                    cipher_driver_info[i].accelerated = DEVCRYPTO_ACCELERATED;
            }
#endif /* CIOCGSESSINFO */
        }
        ioctl(cfd, CIOCFSESSION, &sess.ses);
        if (devcrypto_test_cipher(i)) {
            known_cipher_nids[known_cipher_nids_amount++] = cipher_data[i].nid;
        }
    }
}

static void rebuild_known_cipher_nids(ENGINE *e)
{
    size_t i;

    for (i = 0, known_cipher_nids_amount = 0; i < OSSL_NELEM(cipher_data); i++) {
        if (devcrypto_test_cipher(i))
            known_cipher_nids[known_cipher_nids_amount++] = cipher_data[i].nid;
    }
    ENGINE_unregister_ciphers(e);
    ENGINE_register_ciphers(e);
}

static const EVP_CIPHER *get_cipher_method(int nid)
{
    size_t i = get_cipher_data_index(nid);

    if (i == (size_t)-1)
        return NULL;
    return known_cipher_methods[i];
}

static int get_cipher_nids(const int **nids)
{
    *nids = known_cipher_nids;
    return known_cipher_nids_amount;
}

static void destroy_cipher_method(int nid)
{
    size_t i = get_cipher_data_index(nid);

    EVP_CIPHER_meth_free(known_cipher_methods[i]);
    known_cipher_methods[i] = NULL;
}

static void destroy_all_cipher_methods(void)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(cipher_data); i++) {
        destroy_cipher_method(cipher_data[i].nid);
        OPENSSL_free(cipher_driver_info[i].driver_name);
        cipher_driver_info[i].driver_name = NULL;
    }
}

static int devcrypto_ciphers(ENGINE *e, const EVP_CIPHER **cipher,
    const int **nids, int nid)
{
    if (cipher == NULL)
        return get_cipher_nids(nids);

    *cipher = get_cipher_method(nid);

    return *cipher != NULL;
}

static void devcrypto_select_all_ciphers(int *cipher_list)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(cipher_data); i++)
        cipher_list[i] = 1;
}

static int cryptodev_select_cipher_cb(const char *str, int len, void *usr)
{
    int *cipher_list = (int *)usr;
    char *name;
    const EVP_CIPHER *EVP;
    size_t i;

    if (len == 0)
        return 1;
    if (usr == NULL || (name = OPENSSL_strndup(str, len)) == NULL)
        return 0;
    EVP = EVP_get_cipherbyname(name);
    if (EVP == NULL)
        fprintf(stderr, "devcrypto: unknown cipher %s\n", name);
    else if ((i = find_cipher_data_index(EVP_CIPHER_get_nid(EVP))) != (size_t)-1)
        cipher_list[i] = 1;
    else
        fprintf(stderr, "devcrypto: cipher %s not available\n", name);
    OPENSSL_free(name);
    return 1;
}

static void dump_cipher_info(void)
{
    size_t i;
    const char *name;

    fprintf(stderr, "Information about ciphers supported by the /dev/crypto"
                    " engine:\n");
#ifndef CIOCGSESSINFO
    fprintf(stderr, "CIOCGSESSINFO (session info call) unavailable\n");
#endif
    for (i = 0; i < OSSL_NELEM(cipher_data); i++) {
        name = OBJ_nid2sn(cipher_data[i].nid);
        fprintf(stderr, "Cipher %s, NID=%d, /dev/crypto info: id=%d, ",
            name ? name : "unknown", cipher_data[i].nid,
            cipher_data[i].devcryptoid);
        if (cipher_driver_info[i].status == DEVCRYPTO_STATUS_NO_CIOCGSESSION) {
            fprintf(stderr, "CIOCGSESSION (session open call) failed\n");
            continue;
        }
        fprintf(stderr, "driver=%s ", cipher_driver_info[i].driver_name ? cipher_driver_info[i].driver_name : "unknown");
        if (cipher_driver_info[i].accelerated == DEVCRYPTO_ACCELERATED)
            fprintf(stderr, "(hw accelerated)");
        else if (cipher_driver_info[i].accelerated == DEVCRYPTO_NOT_ACCELERATED)
            fprintf(stderr, "(software)");
        else
            fprintf(stderr, "(acceleration status unknown)");
        if (cipher_driver_info[i].status == DEVCRYPTO_STATUS_FAILURE)
            fprintf(stderr, ". Cipher setup failed");
        fprintf(stderr, "\n");
    }
    fprintf(stderr, "\n");
}

/*
 * We only support digests if the cryptodev implementation supports multiple
 * data updates and session copying.  Otherwise, we would be forced to maintain
 * a cache, which is perilous if there's a lot of data coming in (if someone
 * wants to checksum an OpenSSL tarball, for example).
 */
#if defined(CIOCCPHASH) && defined(COP_FLAG_UPDATE) && defined(COP_FLAG_FINAL)
#define IMPLEMENT_DIGEST

/******************************************************************************
 *
 * Digests
 *
 * Because they all do the same basic operation, we have only one set of
 * method functions for them all to share, and a mapping table between
 * NIDs and cryptodev IDs, with all the necessary size data.
 *
 *****/

struct digest_ctx {
    session_op_t sess;
    /* This signals that the init function was called, not that it succeeded. */
    int init_called;
    unsigned char digest_res[HASH_MAX_LEN];
};

static const struct digest_data_st {
    int nid;
    int blocksize;
    int digestlen;
    int devcryptoid;
} digest_data[] = {
#ifndef OPENSSL_NO_MD5
    { NID_md5, /* MD5_CBLOCK */ 64, 16, CRYPTO_MD5 },
#endif
    { NID_sha1, SHA_CBLOCK, 20, CRYPTO_SHA1 },
#ifndef OPENSSL_NO_RMD160
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_RIPEMD160)
    { NID_ripemd160, /* RIPEMD160_CBLOCK */ 64, 20, CRYPTO_RIPEMD160 },
#endif
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_SHA2_224)
    { NID_sha224, SHA256_CBLOCK, 224 / 8, CRYPTO_SHA2_224 },
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_SHA2_256)
    { NID_sha256, SHA256_CBLOCK, 256 / 8, CRYPTO_SHA2_256 },
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_SHA2_384)
    { NID_sha384, SHA512_CBLOCK, 384 / 8, CRYPTO_SHA2_384 },
#endif
#if !defined(CHECK_BSD_STYLE_MACROS) || defined(CRYPTO_SHA2_512)
    { NID_sha512, SHA512_CBLOCK, 512 / 8, CRYPTO_SHA2_512 },
#endif
};

static size_t find_digest_data_index(int nid)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(digest_data); i++)
        if (nid == digest_data[i].nid)
            return i;
    return (size_t)-1;
}

static size_t get_digest_data_index(int nid)
{
    size_t i = find_digest_data_index(nid);

    if (i != (size_t)-1)
        return i;

    /*
     * Code further down must make sure that only NIDs in the table above
     * are used.  If any other NID reaches this function, there's a grave
     * coding error further down.
     */
    assert("Code that never should be reached" == NULL);
    return -1;
}

static const struct digest_data_st *get_digest_data(int nid)
{
    return &digest_data[get_digest_data_index(nid)];
}

/*
 * Following are the five necessary functions to map OpenSSL functionality
 * with cryptodev: init, update, final, cleanup, and copy.
 */

static int digest_init(EVP_MD_CTX *ctx)
{
    struct digest_ctx *digest_ctx = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(ctx);
    const struct digest_data_st *digest_d = get_digest_data(EVP_MD_CTX_get_type(ctx));

    digest_ctx->init_called = 1;

    memset(&digest_ctx->sess, 0, sizeof(digest_ctx->sess));
    digest_ctx->sess.mac = digest_d->devcryptoid;
    if (ioctl(cfd, CIOCGSESSION, &digest_ctx->sess) < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }
    return 1;
}

static int digest_op(struct digest_ctx *ctx, const void *src, size_t srclen,
    void *res, unsigned int flags)
{
    struct crypt_op cryp;

    memset(&cryp, 0, sizeof(cryp));
    cryp.ses = ctx->sess.ses;
    cryp.len = srclen;
    cryp.src = (void *)src;
    cryp.dst = NULL;
    cryp.mac = res;
    cryp.flags = flags;
    return ioctl(cfd, CIOCCRYPT, &cryp);
}

static int digest_update(EVP_MD_CTX *ctx, const void *data, size_t count)
{
    struct digest_ctx *digest_ctx = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(ctx);

    if (count == 0)
        return 1;

    if (digest_ctx == NULL)
        return 0;

    if (EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_ONESHOT)) {
        if (digest_op(digest_ctx, data, count, digest_ctx->digest_res, 0) >= 0)
            return 1;
    } else if (digest_op(digest_ctx, data, count, NULL, COP_FLAG_UPDATE) >= 0) {
        return 1;
    }

    ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
    return 0;
}

static int digest_final(EVP_MD_CTX *ctx, unsigned char *md)
{
    struct digest_ctx *digest_ctx = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(ctx);

    if (md == NULL || digest_ctx == NULL)
        return 0;

    if (EVP_MD_CTX_test_flags(ctx, EVP_MD_CTX_FLAG_ONESHOT)) {
        memcpy(md, digest_ctx->digest_res, EVP_MD_CTX_get_size(ctx));
    } else if (digest_op(digest_ctx, NULL, 0, md, COP_FLAG_FINAL) < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }

    return 1;
}

static int digest_copy(EVP_MD_CTX *to, const EVP_MD_CTX *from)
{
    struct digest_ctx *digest_from = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(from);
    struct digest_ctx *digest_to = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(to);
    struct cphash_op cphash;

    if (digest_from == NULL || digest_from->init_called != 1)
        return 1;

    if (!digest_init(to)) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }

    cphash.src_ses = digest_from->sess.ses;
    cphash.dst_ses = digest_to->sess.ses;
    if (ioctl(cfd, CIOCCPHASH, &cphash) < 0) {
        ERR_raise_data(ERR_LIB_SYS, errno, "calling ioctl()");
        return 0;
    }
    return 1;
}

static int digest_cleanup(EVP_MD_CTX *ctx)
{
    struct digest_ctx *digest_ctx = (struct digest_ctx *)EVP_MD_CTX_get0_md_data(ctx);

    if (digest_ctx == NULL)
        return 1;

    return clean_devcrypto_session(&digest_ctx->sess);
}

/*
 * Keep tables of known nids, associated methods, selected digests, and
 * driver info.
 * Note that known_digest_nids[] isn't necessarily indexed the same way as
 * digest_data[] above, which the other tables are.
 */
static int known_digest_nids[OSSL_NELEM(digest_data)];
static int known_digest_nids_amount = -1; /* -1 indicates not yet initialised */
static EVP_MD *known_digest_methods[OSSL_NELEM(digest_data)] = {
    NULL,
};
static int selected_digests[OSSL_NELEM(digest_data)];
static struct driver_info_st digest_driver_info[OSSL_NELEM(digest_data)];

static int devcrypto_test_digest(size_t digest_data_index)
{
    return (digest_driver_info[digest_data_index].status == DEVCRYPTO_STATUS_USABLE
        && selected_digests[digest_data_index] == 1
        && (digest_driver_info[digest_data_index].accelerated
                == DEVCRYPTO_ACCELERATED
            || use_softdrivers == DEVCRYPTO_USE_SOFTWARE
            || (digest_driver_info[digest_data_index].accelerated
                    != DEVCRYPTO_NOT_ACCELERATED
                && use_softdrivers == DEVCRYPTO_REJECT_SOFTWARE)));
}

static void rebuild_known_digest_nids(ENGINE *e)
{
    size_t i;

    for (i = 0, known_digest_nids_amount = 0; i < OSSL_NELEM(digest_data); i++) {
        if (devcrypto_test_digest(i))
            known_digest_nids[known_digest_nids_amount++] = digest_data[i].nid;
    }
    ENGINE_unregister_digests(e);
    ENGINE_register_digests(e);
}

static void prepare_digest_methods(void)
{
    size_t i;
    session_op_t sess1, sess2;
#ifdef CIOCGSESSINFO
    struct session_info_op siop;
#endif
    struct cphash_op cphash;

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

    memset(&sess1, 0, sizeof(sess1));
    memset(&sess2, 0, sizeof(sess2));

    for (i = 0, known_digest_nids_amount = 0; i < OSSL_NELEM(digest_data);
        i++) {

        selected_digests[i] = 1;

        /*
         * Check that the digest is usable
         */
        sess1.mac = digest_data[i].devcryptoid;
        sess2.ses = 0;
        if (ioctl(cfd, CIOCGSESSION, &sess1) < 0) {
            digest_driver_info[i].status = DEVCRYPTO_STATUS_NO_CIOCGSESSION;
            goto finish;
        }

#ifdef CIOCGSESSINFO
        /* gather hardware acceleration info from the driver */
        siop.ses = sess1.ses;
        if (ioctl(cfd, CIOCGSESSINFO, &siop) < 0) {
            digest_driver_info[i].accelerated = DEVCRYPTO_ACCELERATION_UNKNOWN;
        } else {
            digest_driver_info[i].driver_name = OPENSSL_strndup(siop.hash_info.cra_driver_name,
                CRYPTODEV_MAX_ALG_NAME);
            if (siop.flags & SIOP_FLAG_KERNEL_DRIVER_ONLY)
                digest_driver_info[i].accelerated = DEVCRYPTO_ACCELERATED;
            else
                digest_driver_info[i].accelerated = DEVCRYPTO_NOT_ACCELERATED;
        }
#endif

        /* digest must be capable of hash state copy */
        sess2.mac = sess1.mac;
        if (ioctl(cfd, CIOCGSESSION, &sess2) < 0) {
            digest_driver_info[i].status = DEVCRYPTO_STATUS_FAILURE;
            goto finish;
        }
        cphash.src_ses = sess1.ses;
        cphash.dst_ses = sess2.ses;
        if (ioctl(cfd, CIOCCPHASH, &cphash) < 0) {
            digest_driver_info[i].status = DEVCRYPTO_STATUS_NO_CIOCCPHASH;
            goto finish;
        }
        if ((known_digest_methods[i] = EVP_MD_meth_new(digest_data[i].nid,
                 NID_undef))
                == NULL
            || !EVP_MD_meth_set_input_blocksize(known_digest_methods[i],
                digest_data[i].blocksize)
            || !EVP_MD_meth_set_result_size(known_digest_methods[i],
                digest_data[i].digestlen)
            || !EVP_MD_meth_set_init(known_digest_methods[i], digest_init)
            || !EVP_MD_meth_set_update(known_digest_methods[i], digest_update)
            || !EVP_MD_meth_set_final(known_digest_methods[i], digest_final)
            || !EVP_MD_meth_set_copy(known_digest_methods[i], digest_copy)
            || !EVP_MD_meth_set_cleanup(known_digest_methods[i], digest_cleanup)
            || !EVP_MD_meth_set_app_datasize(known_digest_methods[i],
                sizeof(struct digest_ctx))) {
            digest_driver_info[i].status = DEVCRYPTO_STATUS_FAILURE;
            EVP_MD_meth_free(known_digest_methods[i]);
            known_digest_methods[i] = NULL;
            goto finish;
        }
        digest_driver_info[i].status = DEVCRYPTO_STATUS_USABLE;
    finish:
        ioctl(cfd, CIOCFSESSION, &sess1.ses);
        if (sess2.ses != 0)
            ioctl(cfd, CIOCFSESSION, &sess2.ses);
        if (devcrypto_test_digest(i))
            known_digest_nids[known_digest_nids_amount++] = digest_data[i].nid;
    }
}

static const EVP_MD *get_digest_method(int nid)
{
    size_t i = get_digest_data_index(nid);

    if (i == (size_t)-1)
        return NULL;
    return known_digest_methods[i];
}

static int get_digest_nids(const int **nids)
{
    *nids = known_digest_nids;
    return known_digest_nids_amount;
}

static void destroy_digest_method(int nid)
{
    size_t i = get_digest_data_index(nid);

    EVP_MD_meth_free(known_digest_methods[i]);
    known_digest_methods[i] = NULL;
}

static void destroy_all_digest_methods(void)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(digest_data); i++) {
        destroy_digest_method(digest_data[i].nid);
        OPENSSL_free(digest_driver_info[i].driver_name);
        digest_driver_info[i].driver_name = NULL;
    }
}

static int devcrypto_digests(ENGINE *e, const EVP_MD **digest,
    const int **nids, int nid)
{
    if (digest == NULL)
        return get_digest_nids(nids);

    *digest = get_digest_method(nid);

    return *digest != NULL;
}

static void devcrypto_select_all_digests(int *digest_list)
{
    size_t i;

    for (i = 0; i < OSSL_NELEM(digest_data); i++)
        digest_list[i] = 1;
}

static int cryptodev_select_digest_cb(const char *str, int len, void *usr)
{
    int *digest_list = (int *)usr;
    char *name;
    const EVP_MD *EVP;
    size_t i;

    if (len == 0)
        return 1;
    if (usr == NULL || (name = OPENSSL_strndup(str, len)) == NULL)
        return 0;
    EVP = EVP_get_digestbyname(name);
    if (EVP == NULL)
        fprintf(stderr, "devcrypto: unknown digest %s\n", name);
    else if ((i = find_digest_data_index(EVP_MD_get_type(EVP))) != (size_t)-1)
        digest_list[i] = 1;
    else
        fprintf(stderr, "devcrypto: digest %s not available\n", name);
    OPENSSL_free(name);
    return 1;
}

static void dump_digest_info(void)
{
    size_t i;
    const char *name;

    fprintf(stderr, "Information about digests supported by the /dev/crypto"
                    " engine:\n");
#ifndef CIOCGSESSINFO
    fprintf(stderr, "CIOCGSESSINFO (session info call) unavailable\n");
#endif

    for (i = 0; i < OSSL_NELEM(digest_data); i++) {
        name = OBJ_nid2sn(digest_data[i].nid);
        fprintf(stderr, "Digest %s, NID=%d, /dev/crypto info: id=%d, driver=%s",
            name ? name : "unknown", digest_data[i].nid,
            digest_data[i].devcryptoid,
            digest_driver_info[i].driver_name ? digest_driver_info[i].driver_name : "unknown");
        if (digest_driver_info[i].status == DEVCRYPTO_STATUS_NO_CIOCGSESSION) {
            fprintf(stderr, ". CIOCGSESSION (session open) failed\n");
            continue;
        }
        if (digest_driver_info[i].accelerated == DEVCRYPTO_ACCELERATED)
            fprintf(stderr, " (hw accelerated)");
        else if (digest_driver_info[i].accelerated == DEVCRYPTO_NOT_ACCELERATED)
            fprintf(stderr, " (software)");
        else
            fprintf(stderr, " (acceleration status unknown)");
        if (cipher_driver_info[i].status == DEVCRYPTO_STATUS_FAILURE)
            fprintf(stderr, ". Cipher setup failed\n");
        else if (digest_driver_info[i].status == DEVCRYPTO_STATUS_NO_CIOCCPHASH)
            fprintf(stderr, ", CIOCCPHASH failed\n");
        else
            fprintf(stderr, ", CIOCCPHASH capable\n");
    }
    fprintf(stderr, "\n");
}

#endif

/******************************************************************************
 *
 * CONTROL COMMANDS
 *
 *****/

#define DEVCRYPTO_CMD_USE_SOFTDRIVERS ENGINE_CMD_BASE
#define DEVCRYPTO_CMD_CIPHERS (ENGINE_CMD_BASE + 1)
#define DEVCRYPTO_CMD_DIGESTS (ENGINE_CMD_BASE + 2)
#define DEVCRYPTO_CMD_DUMP_INFO (ENGINE_CMD_BASE + 3)

static const ENGINE_CMD_DEFN devcrypto_cmds[] = {
#if defined(CIOCGSESSINFO) || defined(CIOCGSESSION2)
    { DEVCRYPTO_CMD_USE_SOFTDRIVERS,
        "USE_SOFTDRIVERS",
        "specifies whether to use software (not accelerated) drivers (" OPENSSL_MSTR(DEVCRYPTO_REQUIRE_ACCELERATED) "=use only accelerated drivers, " OPENSSL_MSTR(DEVCRYPTO_USE_SOFTWARE) "=allow all drivers, " OPENSSL_MSTR(DEVCRYPTO_REJECT_SOFTWARE) "=use if acceleration can't be determined) [default=" OPENSSL_MSTR(DEVCRYPTO_DEFAULT_USE_SOFTDRIVERS) "]",
        ENGINE_CMD_FLAG_NUMERIC },
#endif

    { DEVCRYPTO_CMD_CIPHERS,
        "CIPHERS",
        "either ALL, NONE, or a comma-separated list of ciphers to enable [default=ALL]",
        ENGINE_CMD_FLAG_STRING },

#ifdef IMPLEMENT_DIGEST
    { DEVCRYPTO_CMD_DIGESTS,
        "DIGESTS",
        "either ALL, NONE, or a comma-separated list of digests to enable [default=ALL]",
        ENGINE_CMD_FLAG_STRING },
#endif

    { DEVCRYPTO_CMD_DUMP_INFO,
        "DUMP_INFO",
        "dump info about each algorithm to stderr; use 'openssl engine -pre DUMP_INFO devcrypto'",
        ENGINE_CMD_FLAG_NO_INPUT },

    { 0, NULL, NULL, 0 }
};

static int devcrypto_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void))
{
    int *new_list;
    switch (cmd) {
#if defined(CIOCGSESSINFO) || defined(CIOCGSESSION2)
    case DEVCRYPTO_CMD_USE_SOFTDRIVERS:
        switch (i) {
        case DEVCRYPTO_REQUIRE_ACCELERATED:
        case DEVCRYPTO_USE_SOFTWARE:
        case DEVCRYPTO_REJECT_SOFTWARE:
            break;
        default:
            fprintf(stderr, "devcrypto: invalid value (%ld) for USE_SOFTDRIVERS\n", i);
            return 0;
        }
        if (use_softdrivers == i)
            return 1;
        use_softdrivers = i;
#ifdef IMPLEMENT_DIGEST
        rebuild_known_digest_nids(e);
#endif
        rebuild_known_cipher_nids(e);
        return 1;
#endif /* CIOCGSESSINFO || CIOCGSESSION2 */

    case DEVCRYPTO_CMD_CIPHERS:
        if (p == NULL)
            return 1;
        if (OPENSSL_strcasecmp((const char *)p, "ALL") == 0) {
            devcrypto_select_all_ciphers(selected_ciphers);
        } else if (OPENSSL_strcasecmp((const char *)p, "NONE") == 0) {
            memset(selected_ciphers, 0, sizeof(selected_ciphers));
        } else {
            new_list = OPENSSL_zalloc(sizeof(selected_ciphers));
            if (!CONF_parse_list(p, ',', 1, cryptodev_select_cipher_cb, new_list)) {
                OPENSSL_free(new_list);
                return 0;
            }
            memcpy(selected_ciphers, new_list, sizeof(selected_ciphers));
            OPENSSL_free(new_list);
        }
        rebuild_known_cipher_nids(e);
        return 1;

#ifdef IMPLEMENT_DIGEST
    case DEVCRYPTO_CMD_DIGESTS:
        if (p == NULL)
            return 1;
        if (OPENSSL_strcasecmp((const char *)p, "ALL") == 0) {
            devcrypto_select_all_digests(selected_digests);
        } else if (OPENSSL_strcasecmp((const char *)p, "NONE") == 0) {
            memset(selected_digests, 0, sizeof(selected_digests));
        } else {
            new_list = OPENSSL_zalloc(sizeof(selected_digests));
            if (!CONF_parse_list(p, ',', 1, cryptodev_select_digest_cb, new_list)) {
                OPENSSL_free(new_list);
                return 0;
            }
            memcpy(selected_digests, new_list, sizeof(selected_digests));
            OPENSSL_free(new_list);
        }
        rebuild_known_digest_nids(e);
        return 1;
#endif /* IMPLEMENT_DIGEST */

    case DEVCRYPTO_CMD_DUMP_INFO:
        dump_cipher_info();
#ifdef IMPLEMENT_DIGEST
        dump_digest_info();
#endif
        return 1;

    default:
        break;
    }
    return 0;
}

/******************************************************************************
 *
 * LOAD / UNLOAD
 *
 *****/

/*
 * Opens /dev/crypto
 */
static int open_devcrypto(void)
{
    int fd;

    if (cfd >= 0)
        return 1;

    if ((fd = open("/dev/crypto", O_RDWR, 0)) < 0) {
#ifndef ENGINE_DEVCRYPTO_DEBUG
        if (errno != ENOENT && errno != ENXIO)
#endif
            fprintf(stderr, "Could not open /dev/crypto: %s\n", strerror(errno));
        return 0;
    }

#ifdef CRIOGET
    if (ioctl(fd, CRIOGET, &cfd) < 0) {
        fprintf(stderr, "Could not create crypto fd: %s\n", strerror(errno));
        close(fd);
        cfd = -1;
        return 0;
    }
    close(fd);
#else
    cfd = fd;
#endif

    return 1;
}

static int close_devcrypto(void)
{
    int ret;

    if (cfd < 0)
        return 1;
    ret = close(cfd);
    cfd = -1;
    if (ret != 0) {
        fprintf(stderr, "Error closing /dev/crypto: %s\n", strerror(errno));
        return 0;
    }
    return 1;
}

static int devcrypto_unload(ENGINE *e)
{
    destroy_all_cipher_methods();
#ifdef IMPLEMENT_DIGEST
    destroy_all_digest_methods();
#endif

    close_devcrypto();

    return 1;
}

static int bind_devcrypto(ENGINE *e)
{

    if (!ENGINE_set_id(e, engine_devcrypto_id)
        || !ENGINE_set_name(e, "/dev/crypto engine")
        || !ENGINE_set_destroy_function(e, devcrypto_unload)
        || !ENGINE_set_cmd_defns(e, devcrypto_cmds)
        || !ENGINE_set_ctrl_function(e, devcrypto_ctrl))
        return 0;

    prepare_cipher_methods();
#ifdef IMPLEMENT_DIGEST
    prepare_digest_methods();
#endif

    return (ENGINE_set_ciphers(e, devcrypto_ciphers)
#ifdef IMPLEMENT_DIGEST
        && ENGINE_set_digests(e, devcrypto_digests)
#endif
/*
 * Asymmetric ciphers aren't well supported with /dev/crypto.  Among the BSD
 * implementations, it seems to only exist in FreeBSD, and regarding the
 * parameters in its crypt_kop, the manual crypto(4) has this to say:
 *
 *    The semantics of these arguments are currently undocumented.
 *
 * Reading through the FreeBSD source code doesn't give much more than
 * their CRK_MOD_EXP implementation for ubsec.
 *
 * It doesn't look much better with cryptodev-linux.  They have the crypt_kop
 * structure as well as the command (CRK_*) in cryptodev.h, but no support
 * seems to be implemented at all for the moment.
 *
 * At the time of writing, it seems impossible to write proper support for
 * FreeBSD's asym features without some very deep knowledge and access to
 * specific kernel modules.
 *
 * /Richard Levitte, 2017-05-11
 */
#if 0
        && ENGINE_set_RSA(e, devcrypto_rsa)
#ifndef OPENSSL_NO_DSA
        && ENGINE_set_DSA(e, devcrypto_dsa)
#endif
#ifndef OPENSSL_NO_DH
        && ENGINE_set_DH(e, devcrypto_dh)
#endif
#ifndef OPENSSL_NO_EC
        && ENGINE_set_EC(e, devcrypto_ec)
#endif
#endif
    );
}

#ifdef OPENSSL_NO_DYNAMIC_ENGINE
/*
 * In case this engine is built into libcrypto, then it doesn't offer any
 * ability to be dynamically loadable.
 */
void engine_load_devcrypto_int(void)
{
    ENGINE *e = NULL;

    if (!open_devcrypto())
        return;

    if ((e = ENGINE_new()) == NULL
        || !bind_devcrypto(e)) {
        close_devcrypto();
        ENGINE_free(e);
        return;
    }

    ERR_set_mark();
    ENGINE_add(e);
    /*
     * If the "add" worked, it gets a structural reference. So either way, we
     * release our just-created reference.
     */
    ENGINE_free(e); /* Loose our local reference */
    /*
     * If the "add" didn't work, it was probably a conflict because it was
     * already added (eg. someone calling ENGINE_load_blah then calling
     * ENGINE_load_builtin_engines() perhaps).
     */
    ERR_pop_to_mark();
}

#else

static int bind_helper(ENGINE *e, const char *id)
{
    if ((id && (strcmp(id, engine_devcrypto_id) != 0))
        || !open_devcrypto())
        return 0;
    if (!bind_devcrypto(e)) {
        close_devcrypto();
        return 0;
    }
    return 1;
}

IMPLEMENT_DYNAMIC_CHECK_FN()
IMPLEMENT_DYNAMIC_BIND_FN(bind_helper)

#endif