lib/dns/openssleddsa_link.c

/*
 * Copyright (C) 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_ED25519) || defined(HAVE_OPENSSL_ED448))

#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/evp.h>
#include <openssl/x509.h>

#ifndef NID_ED25519
#error "Ed25519 group is not known (NID_ED25519)"
#endif
#ifndef NID_ED448
#error "Ed448 group is not known (NID_ED448)"
#endif

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

/* OpenSSL doesn't provide direct access to key values */

#define PUBPREFIXLEN    12

static const unsigned char ed25519_pub_prefix[] = {
    0x30, 0x2a, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65,
    0x70, 0x03, 0x21, 0x00
};

static EVP_PKEY *pub_ed25519_to_ossl(const unsigned char *key)
{
    unsigned char buf[PUBPREFIXLEN + DNS_KEY_ED25519SIZE];
    const unsigned char *p;

    memmove(buf, ed25519_pub_prefix, PUBPREFIXLEN);
    memmove(buf + PUBPREFIXLEN, key, DNS_KEY_ED25519SIZE);
    p = buf;
    return (d2i_PUBKEY(NULL, &p, PUBPREFIXLEN + DNS_KEY_ED25519SIZE));
}

static isc_result_t pub_ed25519_from_ossl(EVP_PKEY *pkey,
                      unsigned char *key)
{
    unsigned char buf[PUBPREFIXLEN + DNS_KEY_ED25519SIZE];
    unsigned char *p;
    int len;

    len = i2d_PUBKEY(pkey, NULL);
    if ((len <= DNS_KEY_ED25519SIZE) ||
        (len > PUBPREFIXLEN + DNS_KEY_ED25519SIZE))
        return (DST_R_OPENSSLFAILURE);
    p = buf;
    len = i2d_PUBKEY(pkey, &p);
    if ((len <= DNS_KEY_ED25519SIZE) ||
        (len > PUBPREFIXLEN + DNS_KEY_ED25519SIZE))
        return (DST_R_OPENSSLFAILURE);
    memmove(key, buf + len - DNS_KEY_ED25519SIZE, DNS_KEY_ED25519SIZE);
    return (ISC_R_SUCCESS);
}

static const unsigned char ed448_pub_prefix[] = {
    0x30, 0x2a, 0x30, 0x05, 0x06, 0x03, 0x2b, 0x65,
    0x71, 0x03, 0x21, 0x00
};

static EVP_PKEY *pub_ed448_to_ossl(const unsigned char *key)
{
    unsigned char buf[PUBPREFIXLEN + DNS_KEY_ED448SIZE];
    const unsigned char *p;

    memmove(buf, ed448_pub_prefix, PUBPREFIXLEN);
    memmove(buf + PUBPREFIXLEN, key, DNS_KEY_ED448SIZE);
    p = buf;
    return (d2i_PUBKEY(NULL, &p, PUBPREFIXLEN + DNS_KEY_ED448SIZE));
}

static isc_result_t pub_ed448_from_ossl(EVP_PKEY *pkey,
                    unsigned char *key)
{
    unsigned char buf[PUBPREFIXLEN + DNS_KEY_ED448SIZE];
    unsigned char *p;
    int len;

    len = i2d_PUBKEY(pkey, NULL);
    if ((len <= DNS_KEY_ED448SIZE) ||
        (len > PUBPREFIXLEN + DNS_KEY_ED448SIZE))
        return (DST_R_OPENSSLFAILURE);
    p = buf;
    len = i2d_PUBKEY(pkey, &p);
    if ((len <= DNS_KEY_ED448SIZE) ||
        (len > PUBPREFIXLEN + DNS_KEY_ED448SIZE))
        return (DST_R_OPENSSLFAILURE);
    memmove(key, buf + len - DNS_KEY_ED448SIZE, DNS_KEY_ED448SIZE);
    return (ISC_R_SUCCESS);
}

#define PRIVPREFIXLEN   16

static const unsigned char ed25519_priv_prefix[] = {
    0x30, 0x2e, 0x02, 0x01, 0x00, 0x30, 0x05, 0x06,
    0x03, 0x2b, 0x65, 0x70, 0x04, 0x22, 0x04, 0x20
};

static EVP_PKEY *priv_ed25519_to_ossl(const unsigned char *key)
{
    unsigned char buf[PRIVPREFIXLEN + DNS_KEY_ED25519SIZE];
    const unsigned char *p;

    memmove(buf, ed25519_priv_prefix, PRIVPREFIXLEN);
    memmove(buf + PRIVPREFIXLEN, key, DNS_KEY_ED25519SIZE);
    p = buf;
    return (d2i_PrivateKey(NID_ED25519, NULL, &p,
                   PRIVPREFIXLEN + DNS_KEY_ED25519SIZE));
}

static isc_result_t priv_ed25519_from_ossl(EVP_PKEY *pkey,
                      unsigned char *key)
{
    unsigned char buf[PRIVPREFIXLEN + DNS_KEY_ED25519SIZE];
    unsigned char *p;
    int len;

    len = i2d_PrivateKey(pkey, NULL);
    if ((len <= DNS_KEY_ED25519SIZE) ||
        (len > PRIVPREFIXLEN + DNS_KEY_ED25519SIZE))
        return (DST_R_OPENSSLFAILURE);
    p = buf;
    len = i2d_PrivateKey(pkey, &p);
    if ((len <= DNS_KEY_ED25519SIZE) ||
        (len > PRIVPREFIXLEN + DNS_KEY_ED25519SIZE))
        return (DST_R_OPENSSLFAILURE);
    memmove(key, buf + len - DNS_KEY_ED25519SIZE, DNS_KEY_ED25519SIZE);
    return (ISC_R_SUCCESS);
}

static const unsigned char ed448_priv_prefix[] = {
    0x30, 0x2e, 0x02, 0x01, 0x00, 0x30, 0x05, 0x06,
    0x03, 0x2b, 0x65, 0x71, 0x04, 0x22, 0x04, 0x20
};

static EVP_PKEY *priv_ed448_to_ossl(const unsigned char *key)
{
    unsigned char buf[PRIVPREFIXLEN + DNS_KEY_ED448SIZE];
    const unsigned char *p;

    memmove(buf, ed448_priv_prefix, PRIVPREFIXLEN);
    memmove(buf + PRIVPREFIXLEN, key, DNS_KEY_ED448SIZE);
    p = buf;
    return (d2i_PrivateKey(NID_ED448, NULL, &p,
                   PRIVPREFIXLEN + DNS_KEY_ED448SIZE));
}

static isc_result_t priv_ed448_from_ossl(EVP_PKEY *pkey,
                    unsigned char *key)
{
    unsigned char buf[PRIVPREFIXLEN + DNS_KEY_ED448SIZE];
    unsigned char *p;
    int len;

    len = i2d_PrivateKey(pkey, NULL);
    if ((len <= DNS_KEY_ED448SIZE) ||
        (len > PRIVPREFIXLEN + DNS_KEY_ED448SIZE))
        return (DST_R_OPENSSLFAILURE);
    p = buf;
    len = i2d_PrivateKey(pkey, &p);
    if ((len <= DNS_KEY_ED448SIZE) ||
        (len > PRIVPREFIXLEN + DNS_KEY_ED448SIZE))
        return (DST_R_OPENSSLFAILURE);
    memmove(key, buf + len - DNS_KEY_ED448SIZE, DNS_KEY_ED448SIZE);
    return (ISC_R_SUCCESS);
}

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

static isc_result_t
openssleddsa_createctx(dst_key_t *key, dst_context_t *dctx) {
    isc_buffer_t *buf = NULL;
    isc_result_t result;

    UNUSED(key);
    REQUIRE(dctx->key->key_alg == DST_ALG_ED25519 ||
        dctx->key->key_alg == DST_ALG_ED448);

    result = isc_buffer_allocate(dctx->mctx, &buf, 64);
    dctx->ctxdata.generic = buf;

    return (result);
}

static void
openssleddsa_destroyctx(dst_context_t *dctx) {
    isc_buffer_t *buf = (isc_buffer_t *) dctx->ctxdata.generic;

    REQUIRE(dctx->key->key_alg == DST_ALG_ED25519 ||
        dctx->key->key_alg == DST_ALG_ED448);
    if (buf != NULL)
        isc_buffer_free(&buf);
    dctx->ctxdata.generic = NULL;
}

static isc_result_t
openssleddsa_adddata(dst_context_t *dctx, const isc_region_t *data) {
    isc_buffer_t *buf = (isc_buffer_t *) dctx->ctxdata.generic;
    isc_buffer_t *nbuf = NULL;
    isc_region_t r;
    unsigned int length;
    isc_result_t result;

    REQUIRE(dctx->key->key_alg == DST_ALG_ED25519 ||
        dctx->key->key_alg == DST_ALG_ED448);

    result = isc_buffer_copyregion(buf, data);
    if (result == ISC_R_SUCCESS)
        return (ISC_R_SUCCESS);

    length = isc_buffer_length(buf) + data->length + 64;
    result = isc_buffer_allocate(dctx->mctx, &nbuf, length);
    if (result != ISC_R_SUCCESS)
        return (result);
    isc_buffer_usedregion(buf, &r);
    (void) isc_buffer_copyregion(nbuf, &r);
    (void) isc_buffer_copyregion(nbuf, data);
    isc_buffer_free(&buf);
    dctx->ctxdata.generic = nbuf;

    return (ISC_R_SUCCESS);
}

static isc_result_t
openssleddsa_sign(dst_context_t *dctx, isc_buffer_t *sig) {
    isc_result_t ret;
    dst_key_t *key = dctx->key;
    isc_region_t tbsreg;
    isc_region_t sigreg;
    EVP_PKEY *pkey = key->keydata.pkey;
    EVP_MD_CTX* ctx = EVP_MD_CTX_new();
    isc_buffer_t *buf = (isc_buffer_t *) dctx->ctxdata.generic;
    size_t siglen;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);

    if (ctx == NULL)
        return (ISC_R_NOMEMORY);

    if (key->key_alg == DST_ALG_ED25519)
        siglen = DNS_SIG_ED25519SIZE;
    else
        siglen = DNS_SIG_ED448SIZE;

    isc_buffer_availableregion(sig, &sigreg);
    if (sigreg.length < (unsigned int) siglen)
        DST_RET(ISC_R_NOSPACE);

    isc_buffer_usedregion(buf, &tbsreg);

    if (!EVP_DigestSignInit(ctx, NULL, NULL, NULL, pkey))
        DST_RET(dst__openssl_toresult3(dctx->category,
                           "EVP_DigestSignInit",
                           ISC_R_FAILURE));
    if (!EVP_DigestSign(ctx, sigreg.base, &siglen,
                tbsreg.base, tbsreg.length))
        DST_RET(dst__openssl_toresult3(dctx->category,
                           "EVP_DigestSign",
                           DST_R_SIGNFAILURE));
    isc_buffer_add(sig, (unsigned int) siglen);
    ret = ISC_R_SUCCESS;

 err:
    if (ctx != NULL)
        EVP_MD_CTX_free(ctx);
    isc_buffer_free(&buf);
    dctx->ctxdata.generic = NULL;

    return (ret);
}

static isc_result_t
openssleddsa_verify(dst_context_t *dctx, const isc_region_t *sig) {
    isc_result_t ret;
    dst_key_t *key = dctx->key;
    int status;
    isc_region_t tbsreg;
    EVP_PKEY *pkey = key->keydata.pkey;
    EVP_MD_CTX* ctx = EVP_MD_CTX_new();
    isc_buffer_t *buf = (isc_buffer_t *) dctx->ctxdata.generic;
    unsigned int siglen;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);

    if (ctx == NULL)
        return (ISC_R_NOMEMORY);

    if (key->key_alg == DST_ALG_ED25519)
        siglen = DNS_SIG_ED25519SIZE;
    else
        siglen = DNS_SIG_ED448SIZE;

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

    isc_buffer_usedregion(buf, &tbsreg);

    if (!EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey))
        DST_RET(dst__openssl_toresult3(dctx->category,
                           "EVP_DigestVerifyInit",
                           ISC_R_FAILURE));

    status = EVP_DigestVerify(ctx, sig->base, siglen,
                  tbsreg.base, tbsreg.length);

    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,
                         "EVP_DigestVerify",
                         DST_R_VERIFYFAILURE);
        break;
    }

 err:
    if (ctx != NULL)
        EVP_MD_CTX_free(ctx);
    isc_buffer_free(&buf);
    dctx->ctxdata.generic = NULL;

    return (ret);
}

static isc_boolean_t
openssleddsa_compare(const dst_key_t *key1, const dst_key_t *key2) {
    int status;
    EVP_PKEY *pkey1 = key1->keydata.pkey;
    EVP_PKEY *pkey2 = key2->keydata.pkey;

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

    status = EVP_PKEY_cmp(pkey1, pkey2);
    if (status == 1)
        return (ISC_TRUE);
    return (ISC_FALSE);
}

static isc_result_t
openssleddsa_generate(dst_key_t *key, int unused, void (*callback)(int)) {
    isc_result_t ret;
    EVP_PKEY *pkey = NULL;
    EVP_PKEY_CTX *ctx = NULL;
    int nid, status;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);
    UNUSED(unused);
    UNUSED(callback);

    if (key->key_alg == DST_ALG_ED25519) {
        nid = NID_ED25519;
        key->key_size = DNS_KEY_ED25519SIZE;
    } else {
        nid = NID_ED448;
        key->key_size = DNS_KEY_ED448SIZE;
    }

    ctx = EVP_PKEY_CTX_new_id(nid, NULL);
    if (ctx == NULL)
        return (dst__openssl_toresult2("EVP_PKEY_CTX_new_id",
                           DST_R_OPENSSLFAILURE));

    status = EVP_PKEY_keygen_init(ctx);
    if (status != 1)
        DST_RET (dst__openssl_toresult2("EVP_PKEY_keygen_init",
                        DST_R_OPENSSLFAILURE));

    status = EVP_PKEY_keygen(ctx, &pkey);
    if (status != 1)
        DST_RET (dst__openssl_toresult2("EVP_PKEY_keygen",
                        DST_R_OPENSSLFAILURE));

    key->keydata.pkey = pkey;
    ret = ISC_R_SUCCESS;

 err:
    if (ctx != NULL)
        EVP_PKEY_CTX_free(ctx);
    return (ret);
}

static isc_boolean_t
openssleddsa_isprivate(const dst_key_t *key) {
    EVP_PKEY *pkey = key->keydata.pkey;
    int len;
    unsigned long err;

    if (pkey == NULL)
        return (ISC_FALSE);

    len = i2d_PrivateKey(pkey, NULL);
    if (len > 0)
        return (ISC_TRUE);
    /* can check if first error is EC_R_INVALID_PRIVATE_KEY */
    while ((err = ERR_get_error()) != 0)
        /**/;

    return (ISC_FALSE);
}

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

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

static isc_result_t
openssleddsa_todns(const dst_key_t *key, isc_buffer_t *data) {
    EVP_PKEY *pkey = key->keydata.pkey;
    isc_region_t r;
    isc_result_t result;

    REQUIRE(pkey != NULL);

    pkey = key->keydata.pkey;
    switch (key->key_alg) {
    case DST_ALG_ED25519:
        isc_buffer_availableregion(data, &r);
        if (r.length < DNS_KEY_ED25519SIZE)
            return (ISC_R_NOSPACE);
        result = pub_ed25519_from_ossl(pkey, r.base);
        if (result == ISC_R_SUCCESS)
            isc_buffer_add(data, DNS_KEY_ED25519SIZE);
        return (result);
    case DST_ALG_ED448:
        isc_buffer_availableregion(data, &r);
        if (r.length < DNS_KEY_ED448SIZE)
            return (ISC_R_NOSPACE);
        result = pub_ed448_from_ossl(pkey, r.base);
        if (result == ISC_R_SUCCESS)
            isc_buffer_add(data, DNS_KEY_ED448SIZE);
        return (result);
    default:
        INSIST(0);
    }
}

static isc_result_t
openssleddsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
    EVP_PKEY *pkey;
    isc_region_t r;
    unsigned int len;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);

    isc_buffer_remainingregion(data, &r);
    if (r.length == 0)
        return (ISC_R_SUCCESS);
    if (key->key_alg == DST_ALG_ED25519) {
        len = DNS_KEY_ED25519SIZE;
        if (r.length < len)
            return (DST_R_INVALIDPUBLICKEY);
        pkey = pub_ed25519_to_ossl(r.base);
    } else {
        len = DNS_KEY_ED448SIZE;
        if (r.length < len)
            return (DST_R_INVALIDPUBLICKEY);
        pkey = pub_ed448_to_ossl(r.base);
    }
    if (pkey == NULL)
        return (dst__openssl_toresult(ISC_R_FAILURE));
    isc_buffer_forward(data, len);
    key->keydata.pkey = pkey;
    key->key_size = len;
    return (ISC_R_SUCCESS);
}

static isc_result_t
openssleddsa_tofile(const dst_key_t *key, const char *directory) {
    isc_result_t ret;
    EVP_PKEY *pkey;
    dst_private_t priv;
    unsigned char *buf = NULL;
    unsigned int len;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);

    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;
    if (key->key_alg == DST_ALG_ED25519) {
        len = DNS_KEY_ED25519SIZE;
        buf = isc_mem_get(key->mctx, len);
        if (buf == NULL)
            return (ISC_R_NOMEMORY);
        priv.elements[0].tag = TAG_EDDSA_PRIVATEKEY;
        priv.elements[0].length = len;
        ret = priv_ed25519_from_ossl(pkey, buf);
        if (ret != ISC_R_SUCCESS)
            DST_RET (dst__openssl_toresult(ret));
        priv.elements[0].data = buf;
        priv.nelements = 1;
        ret = dst__privstruct_writefile(key, &priv, directory);
    } else {
        len = DNS_KEY_ED448SIZE;
        buf = isc_mem_get(key->mctx, len);
        if (buf == NULL)
            return (ISC_R_NOMEMORY);
        priv.elements[0].tag = TAG_EDDSA_PRIVATEKEY;
        priv.elements[0].length = len;
        ret = priv_ed448_from_ossl(pkey, buf);
        if (ret != ISC_R_SUCCESS)
            DST_RET (dst__openssl_toresult(ret));
        priv.elements[0].data = buf;
        priv.nelements = 1;
        ret = dst__privstruct_writefile(key, &priv, directory);
    }

 err:
    if (buf != NULL)
        isc_mem_put(key->mctx, buf, len);
    return (ret);
}

static isc_result_t
eddsa_check(EVP_PKEY *privkey, dst_key_t *pub)
{
    EVP_PKEY *pkey;

    if (pub == NULL)
        return (ISC_R_SUCCESS);
    pkey = pub->keydata.pkey;
    if (pkey == NULL)
        return (ISC_R_SUCCESS);
    if (EVP_PKEY_cmp(privkey, pkey) == 1)
        return (ISC_R_SUCCESS);
    return (ISC_R_FAILURE);
}

static isc_result_t
openssleddsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
    dst_private_t priv;
    isc_result_t ret;
    EVP_PKEY *pkey = NULL;
    unsigned int len;
    isc_mem_t *mctx = key->mctx;

    REQUIRE(key->key_alg == DST_ALG_ED25519 ||
        key->key_alg == DST_ALG_ED448);

    /* read private key file */
    ret = dst__privstruct_parse(key, DST_ALG_ED25519, 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_ED25519) {
        len = DNS_KEY_ED25519SIZE;
        if (priv.elements[0].length < len)
            DST_RET(DST_R_INVALIDPRIVATEKEY);
        pkey = priv_ed25519_to_ossl(priv.elements[0].data);
    } else {
        len = DNS_KEY_ED448SIZE;
        if (priv.elements[0].length < len)
            DST_RET(DST_R_INVALIDPRIVATEKEY);
        pkey = priv_ed448_to_ossl(priv.elements[0].data);
    }
    if (pkey == NULL)
        DST_RET (dst__openssl_toresult(DST_R_OPENSSLFAILURE));
    if (eddsa_check(pkey, pub) != ISC_R_SUCCESS) {
        EVP_PKEY_free(pkey);
        DST_RET(DST_R_INVALIDPRIVATEKEY);
    }
    key->keydata.pkey = pkey;
    key->key_size = len;
    ret = ISC_R_SUCCESS;

 err:
    dst__privstruct_free(&priv, mctx);
    isc_safe_memwipe(&priv, sizeof(priv));
    return (ret);
}

static dst_func_t openssleddsa_functions = {
    openssleddsa_createctx,
    NULL, /*%< createctx2 */
    openssleddsa_destroyctx,
    openssleddsa_adddata,
    openssleddsa_sign,
    openssleddsa_verify,
    NULL, /*%< verify2 */
    NULL, /*%< computesecret */
    openssleddsa_compare,
    NULL, /*%< paramcompare */
    openssleddsa_generate,
    openssleddsa_isprivate,
    openssleddsa_destroy,
    openssleddsa_todns,
    openssleddsa_fromdns,
    openssleddsa_tofile,
    openssleddsa_parse,
    NULL, /*%< cleanup */
    NULL, /*%< fromlabel */
    NULL, /*%< dump */
    NULL, /*%< restore */
};

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

#else /* HAVE_OPENSSL_EDxxx */

#include <isc/util.h>

EMPTY_TRANSLATION_UNIT

#endif /* HAVE_OPENSSL_EDxxx */
/*! \file */