lib/dns/opensslecdsa_link.c

/*
 * Copyright (C) 2012-2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#include <config.h>

#if defined(OPENSSL) && defined(HAVE_OPENSSL_ECDSA)

#if !defined(HAVE_EVP_SHA256) || !defined(HAVE_EVP_SHA384)
#error "ECDSA without EVP for SHA2?"
#endif

#include <isc/entropy.h>
#include <isc/mem.h>
#include <isc/safe.h>
#include <isc/sha2.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/keyvalues.h>
#include <dst/result.h>

#include "dst_internal.h"
#include "dst_openssl.h"
#include "dst_parse.h"

#include <openssl/err.h>
#include <openssl/objects.h>
#include <openssl/ecdsa.h>
#include <openssl/bn.h>

#ifndef NID_X9_62_prime256v1
#error "P-256 group is not known (NID_X9_62_prime256v1)"
#endif
#ifndef NID_secp384r1
#error "P-384 group is not known (NID_secp384r1)"
#endif

#define DST_RET(a) {ret = a; goto err;}

#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
/* From OpenSSL 1.1 */
static void
ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps) {
    if (pr != NULL)
        *pr = sig->r;
    if (ps != NULL)
        *ps = sig->s;
}

static int
ECDSA_SIG_set0(ECDSA_SIG *sig, BIGNUM *r, BIGNUM *s) {
    if (r == NULL || s == NULL)
        return 0;

    BN_clear_free(sig->r);
    BN_clear_free(sig->s);
    sig->r = r;
    sig->s = s;

    return 1;
}
#endif

static isc_result_t opensslecdsa_todns(const dst_key_t *key,
                       isc_buffer_t *data);

static isc_result_t
opensslecdsa_createctx(dst_key_t *key, dst_context_t *dctx) {
    EVP_MD_CTX *evp_md_ctx;
    const EVP_MD *type = NULL;

    UNUSED(key);
    REQUIRE(dctx->key->key_alg == DST_ALG_ECDSA256 ||
        dctx->key->key_alg == DST_ALG_ECDSA384);

    evp_md_ctx = EVP_MD_CTX_create();
    if (evp_md_ctx == NULL)
        return (ISC_R_NOMEMORY);
    if (dctx->key->key_alg == DST_ALG_ECDSA256)
        type = EVP_sha256();
    else
        type = EVP_sha384();

    if (!EVP_DigestInit_ex(evp_md_ctx, type, NULL)) {
        EVP_MD_CTX_destroy(evp_md_ctx);
        return (dst__openssl_toresult3(dctx->category,
                           "EVP_DigestInit_ex",
                           ISC_R_FAILURE));
    }

    dctx->ctxdata.evp_md_ctx = evp_md_ctx;

    return (ISC_R_SUCCESS);
}

static void
opensslecdsa_destroyctx(dst_context_t *dctx) {
    EVP_MD_CTX *evp_md_ctx = dctx->ctxdata.evp_md_ctx;

    REQUIRE(dctx->key->key_alg == DST_ALG_ECDSA256 ||
        dctx->key->key_alg == DST_ALG_ECDSA384);

    if (evp_md_ctx != NULL) {
        EVP_MD_CTX_destroy(evp_md_ctx);
        dctx->ctxdata.evp_md_ctx = NULL;
    }
}

static isc_result_t
opensslecdsa_adddata(dst_context_t *dctx, const isc_region_t *data) {
    EVP_MD_CTX *evp_md_ctx = dctx->ctxdata.evp_md_ctx;

    REQUIRE(dctx->key->key_alg == DST_ALG_ECDSA256 ||
        dctx->key->key_alg == DST_ALG_ECDSA384);

    if (!EVP_DigestUpdate(evp_md_ctx, data->base, data->length))
        return (dst__openssl_toresult3(dctx->category,
                           "EVP_DigestUpdate",
                           ISC_R_FAILURE));

    return (ISC_R_SUCCESS);
}

static int
BN_bn2bin_fixed(const BIGNUM *bn, unsigned char *buf, int size) {
    int bytes = size - BN_num_bytes(bn);

    while (bytes-- > 0)
        *buf++ = 0;
    BN_bn2bin(bn, buf);
    return (size);
}

static isc_result_t
opensslecdsa_sign(dst_context_t *dctx, isc_buffer_t *sig) {
    isc_result_t ret;
    dst_key_t *key = dctx->key;
    isc_region_t region;
    ECDSA_SIG *ecdsasig;
    EVP_MD_CTX *evp_md_ctx = dctx->ctxdata.evp_md_ctx;
    EVP_PKEY *pkey = key->keydata.pkey;
    EC_KEY *eckey = EVP_PKEY_get1_EC_KEY(pkey);
    unsigned int dgstlen, siglen;
    unsigned char digest[EVP_MAX_MD_SIZE];
    const BIGNUM *r, *s;

    REQUIRE(key->key_alg == DST_ALG_ECDSA256 ||
        key->key_alg == DST_ALG_ECDSA384);

    if (eckey == NULL)
        return (ISC_R_FAILURE);

    if (key->key_alg == DST_ALG_ECDSA256)
        siglen = DNS_SIG_ECDSA256SIZE;
    else
        siglen = DNS_SIG_ECDSA384SIZE;

    isc_buffer_availableregion(sig, &region);
    if (region.length < siglen)
        DST_RET(ISC_R_NOSPACE);

    if (!EVP_DigestFinal(evp_md_ctx, digest, &dgstlen))
        DST_RET(dst__openssl_toresult3(dctx->category,
                           "EVP_DigestFinal",
                           ISC_R_FAILURE));

    ecdsasig = ECDSA_do_sign(digest, dgstlen, eckey);
    if (ecdsasig == NULL)
        DST_RET(dst__openssl_toresult3(dctx->category,
                           "ECDSA_do_sign",
                           DST_R_SIGNFAILURE));
    ECDSA_SIG_get0(ecdsasig, &r, &s);
    BN_bn2bin_fixed(r, region.base, siglen / 2);
    isc_region_consume(&region, siglen / 2);
    BN_bn2bin_fixed(s, region.base, siglen / 2);
    isc_region_consume(&region, siglen / 2);
    ECDSA_SIG_free(ecdsasig);
    isc_buffer_add(sig, siglen);
    ret = ISC_R_SUCCESS;

 err:
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static isc_result_t
opensslecdsa_verify(dst_context_t *dctx, const isc_region_t *sig) {
    isc_result_t ret;
    dst_key_t *key = dctx->key;
    int status;
    unsigned char *cp = sig->base;
    ECDSA_SIG *ecdsasig = NULL;
    EVP_MD_CTX *evp_md_ctx = dctx->ctxdata.evp_md_ctx;
    EVP_PKEY *pkey = key->keydata.pkey;
    EC_KEY *eckey = EVP_PKEY_get1_EC_KEY(pkey);
    unsigned int dgstlen, siglen;
    unsigned char digest[EVP_MAX_MD_SIZE];
    BIGNUM *r = NULL, *s = NULL ;

    REQUIRE(key->key_alg == DST_ALG_ECDSA256 ||
        key->key_alg == DST_ALG_ECDSA384);

    if (eckey == NULL)
        return (ISC_R_FAILURE);

    if (key->key_alg == DST_ALG_ECDSA256)
        siglen = DNS_SIG_ECDSA256SIZE;
    else
        siglen = DNS_SIG_ECDSA384SIZE;

    if (sig->length != siglen)
        return (DST_R_VERIFYFAILURE);

    if (!EVP_DigestFinal_ex(evp_md_ctx, digest, &dgstlen))
        DST_RET (dst__openssl_toresult3(dctx->category,
                        "EVP_DigestFinal_ex",
                        ISC_R_FAILURE));

    ecdsasig = ECDSA_SIG_new();
    if (ecdsasig == NULL)
        DST_RET (ISC_R_NOMEMORY);
    r = BN_bin2bn(cp, siglen / 2, NULL);
    cp += siglen / 2;
    s = BN_bin2bn(cp, siglen / 2, NULL);
    ECDSA_SIG_set0(ecdsasig, r, s);
    /* cp += siglen / 2; */

    status = ECDSA_do_verify(digest, dgstlen, ecdsasig, eckey);
    switch (status) {
    case 1:
        ret = ISC_R_SUCCESS;
        break;
    case 0:
        ret = dst__openssl_toresult(DST_R_VERIFYFAILURE);
        break;
    default:
        ret = dst__openssl_toresult3(dctx->category,
                         "ECDSA_do_verify",
                         DST_R_VERIFYFAILURE);
        break;
    }

 err:
    if (ecdsasig != NULL)
        ECDSA_SIG_free(ecdsasig);
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static isc_boolean_t
opensslecdsa_compare(const dst_key_t *key1, const dst_key_t *key2) {
    isc_boolean_t ret;
    int status;
    EVP_PKEY *pkey1 = key1->keydata.pkey;
    EVP_PKEY *pkey2 = key2->keydata.pkey;
    EC_KEY *eckey1 = NULL;
    EC_KEY *eckey2 = NULL;
    const BIGNUM *priv1, *priv2;

    if (pkey1 == NULL && pkey2 == NULL)
        return (ISC_TRUE);
    else if (pkey1 == NULL || pkey2 == NULL)
        return (ISC_FALSE);

    eckey1 = EVP_PKEY_get1_EC_KEY(pkey1);
    eckey2 = EVP_PKEY_get1_EC_KEY(pkey2);
    if (eckey1 == NULL && eckey2 == NULL) {
        DST_RET (ISC_TRUE);
    } else if (eckey1 == NULL || eckey2 == NULL)
        DST_RET (ISC_FALSE);

    status = EVP_PKEY_cmp(pkey1, pkey2);
    if (status != 1)
        DST_RET (ISC_FALSE);

    priv1 = EC_KEY_get0_private_key(eckey1);
    priv2 = EC_KEY_get0_private_key(eckey2);
    if (priv1 != NULL || priv2 != NULL) {
        if (priv1 == NULL || priv2 == NULL)
            DST_RET (ISC_FALSE);
        if (BN_cmp(priv1, priv2) != 0)
            DST_RET (ISC_FALSE);
    }
    ret = ISC_TRUE;

 err:
    if (eckey1 != NULL)
        EC_KEY_free(eckey1);
    if (eckey2 != NULL)
        EC_KEY_free(eckey2);
    return (ret);
}

static isc_result_t
opensslecdsa_generate(dst_key_t *key, int unused, void (*callback)(int)) {
    isc_result_t ret;
    EVP_PKEY *pkey;
    EC_KEY *eckey = NULL;
    int group_nid;

    REQUIRE(key->key_alg == DST_ALG_ECDSA256 ||
        key->key_alg == DST_ALG_ECDSA384);
    UNUSED(unused);
    UNUSED(callback);

    if (key->key_alg == DST_ALG_ECDSA256) {
        group_nid = NID_X9_62_prime256v1;
        key->key_size = DNS_KEY_ECDSA256SIZE * 4;
    } else {
        group_nid = NID_secp384r1;
        key->key_size = DNS_KEY_ECDSA384SIZE * 4;
    }

    eckey = EC_KEY_new_by_curve_name(group_nid);
    if (eckey == NULL)
        return (dst__openssl_toresult2("EC_KEY_new_by_curve_name",
                           DST_R_OPENSSLFAILURE));

    if (EC_KEY_generate_key(eckey) != 1)
        DST_RET (dst__openssl_toresult2("EC_KEY_generate_key",
                        DST_R_OPENSSLFAILURE));

    pkey = EVP_PKEY_new();
    if (pkey == NULL)
        DST_RET (ISC_R_NOMEMORY);
    if (!EVP_PKEY_set1_EC_KEY(pkey, eckey)) {
        EVP_PKEY_free(pkey);
        DST_RET (ISC_R_FAILURE);
    }
    key->keydata.pkey = pkey;
    ret = ISC_R_SUCCESS;

 err:
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static isc_boolean_t
opensslecdsa_isprivate(const dst_key_t *key) {
    isc_boolean_t ret;
    EVP_PKEY *pkey = key->keydata.pkey;
    EC_KEY *eckey = EVP_PKEY_get1_EC_KEY(pkey);

    ret = ISC_TF(eckey != NULL && EC_KEY_get0_private_key(eckey) != NULL);
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static void
opensslecdsa_destroy(dst_key_t *key) {
    EVP_PKEY *pkey = key->keydata.pkey;

    EVP_PKEY_free(pkey);
    key->keydata.pkey = NULL;
}

static isc_result_t
opensslecdsa_todns(const dst_key_t *key, isc_buffer_t *data) {
    isc_result_t ret;
    EVP_PKEY *pkey;
    EC_KEY *eckey = NULL;
    isc_region_t r;
    int len;
    unsigned char *cp;
    unsigned char buf[DNS_KEY_ECDSA384SIZE + 1];

    REQUIRE(key->keydata.pkey != NULL);

    pkey = key->keydata.pkey;
    eckey = EVP_PKEY_get1_EC_KEY(pkey);
    if (eckey == NULL)
        return (dst__openssl_toresult(ISC_R_FAILURE));
    len = i2o_ECPublicKey(eckey, NULL);
    /* skip form */
    len--;

    isc_buffer_availableregion(data, &r);
    if (r.length < (unsigned int) len)
        DST_RET (ISC_R_NOSPACE);
    cp = buf;
    if (!i2o_ECPublicKey(eckey, &cp))
        DST_RET (dst__openssl_toresult(ISC_R_FAILURE));
    memmove(r.base, buf + 1, len);
    isc_buffer_add(data, len);
    ret = ISC_R_SUCCESS;

 err:
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static isc_result_t
opensslecdsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
    isc_result_t ret;
    EVP_PKEY *pkey;
    EC_KEY *eckey = NULL;
    isc_region_t r;
    int group_nid;
    unsigned int len;
    const unsigned char *cp;
    unsigned char buf[DNS_KEY_ECDSA384SIZE + 1];

    REQUIRE(key->key_alg == DST_ALG_ECDSA256 ||
        key->key_alg == DST_ALG_ECDSA384);

    if (key->key_alg == DST_ALG_ECDSA256) {
        len = DNS_KEY_ECDSA256SIZE;
        group_nid = NID_X9_62_prime256v1;
    } else {
        len = DNS_KEY_ECDSA384SIZE;
        group_nid = NID_secp384r1;
    }

    isc_buffer_remainingregion(data, &r);
    if (r.length == 0)
        return (ISC_R_SUCCESS);
    if (r.length < len)
        return (DST_R_INVALIDPUBLICKEY);

    eckey = EC_KEY_new_by_curve_name(group_nid);
    if (eckey == NULL)
        return (dst__openssl_toresult(DST_R_OPENSSLFAILURE));

    buf[0] = POINT_CONVERSION_UNCOMPRESSED;
    memmove(buf + 1, r.base, len);
    cp = buf;
    if (o2i_ECPublicKey(&eckey,
                (const unsigned char **) &cp,
                (long) len + 1) == NULL)
        DST_RET (dst__openssl_toresult(DST_R_INVALIDPUBLICKEY));
    if (EC_KEY_check_key(eckey) != 1)
        DST_RET (dst__openssl_toresult(DST_R_INVALIDPUBLICKEY));

    pkey = EVP_PKEY_new();
    if (pkey == NULL)
        DST_RET (ISC_R_NOMEMORY);
    if (!EVP_PKEY_set1_EC_KEY(pkey, eckey)) {
        EVP_PKEY_free(pkey);
        DST_RET (dst__openssl_toresult(ISC_R_FAILURE));
    }

    isc_buffer_forward(data, len);
    key->keydata.pkey = pkey;
    key->key_size = len * 4;
    ret = ISC_R_SUCCESS;

 err:
    if (eckey != NULL)
        EC_KEY_free(eckey);
    return (ret);
}

static isc_result_t
opensslecdsa_tofile(const dst_key_t *key, const char *directory) {
    isc_result_t ret;
    EVP_PKEY *pkey;
    EC_KEY *eckey = NULL;
    const BIGNUM *privkey;
    dst_private_t priv;
    unsigned char *buf = NULL;

    if (key->keydata.pkey == NULL)
        return (DST_R_NULLKEY);

    if (key->external) {
        priv.nelements = 0;
        return (dst__privstruct_writefile(key, &priv, directory));
    }

    pkey = key->keydata.pkey;
    eckey = EVP_PKEY_get1_EC_KEY(pkey);
    if (eckey == NULL)
        return (dst__openssl_toresult(DST_R_OPENSSLFAILURE));
    privkey = EC_KEY_get0_private_key(eckey);
    if (privkey == NULL)
        DST_RET (ISC_R_FAILURE);

    buf = isc_mem_get(key->mctx, BN_num_bytes(privkey));
    if (buf == NULL)
        DST_RET (ISC_R_NOMEMORY);

    priv.elements[0].tag = TAG_ECDSA_PRIVATEKEY;
    priv.elements[0].length = BN_num_bytes(privkey);
    BN_bn2bin(privkey, buf);
    priv.elements[0].data = buf;
    priv.nelements = 1;
    ret = dst__privstruct_writefile(key, &priv, directory);

 err:
    if (eckey != NULL)
        EC_KEY_free(eckey);
    if (buf != NULL)
        isc_mem_put(key->mctx, buf, BN_num_bytes(privkey));
    return (ret);
}

static isc_result_t
ecdsa_check(EC_KEY *eckey, dst_key_t *pub)
{
    isc_result_t ret = ISC_R_FAILURE;
    EVP_PKEY *pkey;
    EC_KEY *pubeckey = NULL;
    const EC_POINT *pubkey;

    if (pub == NULL)
        return (ISC_R_SUCCESS);
    pkey = pub->keydata.pkey;
    if (pkey == NULL)
        return (ISC_R_SUCCESS);
    pubeckey = EVP_PKEY_get1_EC_KEY(pkey);
    if (pubeckey == NULL)
        return (ISC_R_SUCCESS);
    pubkey = EC_KEY_get0_public_key(pubeckey);
    if (pubkey == NULL)
        DST_RET (ISC_R_SUCCESS);
    if (EC_KEY_set_public_key(eckey, pubkey) != 1)
        DST_RET (ISC_R_SUCCESS);
    if (EC_KEY_check_key(eckey) == 1)
        DST_RET (ISC_R_SUCCESS);

 err:
    if (pubeckey != NULL)
        EC_KEY_free(pubeckey);
    return (ret);
}

static isc_result_t
opensslecdsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
    dst_private_t priv;
    isc_result_t ret;
    EVP_PKEY *pkey;
    EC_KEY *eckey = NULL;
    BIGNUM *privkey = NULL;
    int group_nid;
    isc_mem_t *mctx = key->mctx;

    REQUIRE(key->key_alg == DST_ALG_ECDSA256 ||
        key->key_alg == DST_ALG_ECDSA384);

    /* read private key file */
    ret = dst__privstruct_parse(key, DST_ALG_ECDSA256, lexer, mctx, &priv);
    if (ret != ISC_R_SUCCESS)
        goto err;

    if (key->external) {
        if (priv.nelements != 0)
            DST_RET(DST_R_INVALIDPRIVATEKEY);
        if (pub == NULL)
            DST_RET(DST_R_INVALIDPRIVATEKEY);
        key->keydata.pkey = pub->keydata.pkey;
        pub->keydata.pkey = NULL;
        dst__privstruct_free(&priv, mctx);
        isc_safe_memwipe(&priv, sizeof(priv));
        return (ISC_R_SUCCESS);
    }

    if (key->key_alg == DST_ALG_ECDSA256)
        group_nid = NID_X9_62_prime256v1;
    else
        group_nid = NID_secp384r1;

    eckey = EC_KEY_new_by_curve_name(group_nid);
    if (eckey == NULL)
        return (dst__openssl_toresult(DST_R_OPENSSLFAILURE));

    privkey = BN_bin2bn(priv.elements[0].data,
                priv.elements[0].length, NULL);
    if (privkey == NULL)
        DST_RET(ISC_R_NOMEMORY);
    if (!EC_KEY_set_private_key(eckey, privkey))
        DST_RET(ISC_R_NOMEMORY);
    if (ecdsa_check(eckey, pub) != ISC_R_SUCCESS)
        DST_RET(DST_R_INVALIDPRIVATEKEY);

    pkey = EVP_PKEY_new();
    if (pkey == NULL)
        DST_RET (ISC_R_NOMEMORY);
    if (!EVP_PKEY_set1_EC_KEY(pkey, eckey)) {
        EVP_PKEY_free(pkey);
        DST_RET (dst__openssl_toresult(DST_R_OPENSSLFAILURE));
    }
    key->keydata.pkey = pkey;
    if (key->key_alg == DST_ALG_ECDSA256)
        key->key_size = DNS_KEY_ECDSA256SIZE * 4;
    else
        key->key_size = DNS_KEY_ECDSA384SIZE * 4;
    ret = ISC_R_SUCCESS;

 err:
    if (privkey != NULL)
        BN_clear_free(privkey);
    if (eckey != NULL)
        EC_KEY_free(eckey);
    dst__privstruct_free(&priv, mctx);
    isc_safe_memwipe(&priv, sizeof(priv));
    return (ret);
}

static dst_func_t opensslecdsa_functions = {
    opensslecdsa_createctx,
    NULL, /*%< createctx2 */
    opensslecdsa_destroyctx,
    opensslecdsa_adddata,
    opensslecdsa_sign,
    opensslecdsa_verify,
    NULL, /*%< verify2 */
    NULL, /*%< computesecret */
    opensslecdsa_compare,
    NULL, /*%< paramcompare */
    opensslecdsa_generate,
    opensslecdsa_isprivate,
    opensslecdsa_destroy,
    opensslecdsa_todns,
    opensslecdsa_fromdns,
    opensslecdsa_tofile,
    opensslecdsa_parse,
    NULL, /*%< cleanup */
    NULL, /*%< fromlabel */
    NULL, /*%< dump */
    NULL, /*%< restore */
};

isc_result_t
dst__opensslecdsa_init(dst_func_t **funcp) {
    REQUIRE(funcp != NULL);
    if (*funcp == NULL)
        *funcp = &opensslecdsa_functions;
    return (ISC_R_SUCCESS);
}

#else /* HAVE_OPENSSL_ECDSA */

#include <isc/util.h>

EMPTY_TRANSLATION_UNIT

#endif /* HAVE_OPENSSL_ECDSA */
/*! \file */