/src/openssl/providers/implementations/exchange/dh_exch.c

Source (jump to first uncovered line)
/*
 * Copyright 2019-2024 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
 */

/*
 * DH low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#include <string.h>
#include <openssl/crypto.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/proverr.h>
#include <openssl/params.h>
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/securitycheck.h"
#include "crypto/dh.h"

static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
static OSSL_FUNC_keyexch_init_fn dh_init;
static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
static OSSL_FUNC_keyexch_derive_fn dh_derive;
static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;

/*
 * This type is only really used to handle some legacy related functionality.
 * If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
 * here and then create and run a KDF after the key is derived.
 * Note that X942 has 2 variants of key derivation:
 *   (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
 *   the counter embedded in it.
 *   (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
 *       done by creating a "X963KDF".
 */
enum kdf_type {
    PROV_DH_KDF_NONE = 0,
    PROV_DH_KDF_X9_42_ASN1
};

/*
 * What's passed as an actual key is defined by the KEYMGMT interface.
 * We happen to know that our KEYMGMT simply passes DH structures, so
 * we use that here too.
 */

typedef struct {
    OSSL_LIB_CTX *libctx;
    DH *dh;
    DH *dhpeer;
    unsigned int pad : 1;

    /* DH KDF */
    /* KDF (if any) to use for DH */
    enum kdf_type kdf_type;
    /* Message digest to use for key derivation */
    EVP_MD *kdf_md;
    /* User key material */
    unsigned char *kdf_ukm;
    size_t kdf_ukmlen;
    /* KDF output length */
    size_t kdf_outlen;
    char *kdf_cekalg;
    OSSL_FIPS_IND_DECLARE
} PROV_DH_CTX;

static void *dh_newctx(void *provctx)
{
    PROV_DH_CTX *pdhctx;

    if (!ossl_prov_is_running())
        return NULL;

    pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
    if (pdhctx == NULL)
        return NULL;
    OSSL_FIPS_IND_INIT(pdhctx)
    pdhctx->libctx = PROV_LIBCTX_OF(provctx);
    pdhctx->kdf_type = PROV_DH_KDF_NONE;
    return pdhctx;
}

#ifdef FIPS_MODULE
static int dh_check_key(PROV_DH_CTX *ctx)
{
    int key_approved = ossl_dh_check_key(ctx->dh);

    if (!key_approved) {
        if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
                                         ctx->libctx, "DH Init", "DH Key",
                                         ossl_fips_config_securitycheck_enabled)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
            return 0;
        }
    }
    return 1;
}

static int digest_check(PROV_DH_CTX *ctx, const EVP_MD *md)
{
    return ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(ctx),
                                           OSSL_FIPS_IND_SETTABLE1, ctx->libctx,
                                           md, "DH Set Ctx");
}
#endif

static int dh_init(void *vpdhctx, void *vdh, const OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running()
            || pdhctx == NULL
            || vdh == NULL
            || !DH_up_ref(vdh))
        return 0;
    DH_free(pdhctx->dh);
    pdhctx->dh = vdh;
    pdhctx->kdf_type = PROV_DH_KDF_NONE;

    OSSL_FIPS_IND_SET_APPROVED(pdhctx)
    if (!dh_set_ctx_params(pdhctx, params))
        return 0;
#ifdef FIPS_MODULE
    if (!dh_check_key(pdhctx))
        return 0;
#endif
    return 1;
}

/* The 2 parties must share the same domain parameters */
static int dh_match_params(DH *priv, DH *peer)
{
    int ret;
    FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
    FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);

    ret = dhparams_priv != NULL
          && dhparams_peer != NULL
          && ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, 1);
    if (!ret)
        ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
    return ret;
}

static int dh_set_peer(void *vpdhctx, void *vdh)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running()
            || pdhctx == NULL
            || vdh == NULL
            || !dh_match_params(vdh, pdhctx->dh)
            || !DH_up_ref(vdh))
        return 0;
    DH_free(pdhctx->dhpeer);
    pdhctx->dhpeer = vdh;
    return 1;
}

static int dh_plain_derive(void *vpdhctx,
                           unsigned char *secret, size_t *secretlen,
                           size_t outlen, unsigned int pad)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    int ret;
    size_t dhsize;
    const BIGNUM *pub_key = NULL;

    if (pdhctx->dh == NULL || pdhctx->dhpeer == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
        return 0;
    }

    dhsize = (size_t)DH_size(pdhctx->dh);
    if (secret == NULL) {
        *secretlen = dhsize;
        return 1;
    }
    if (outlen < dhsize) {
        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
        return 0;
    }

    DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
    if (pad)
        ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
    else
        ret = DH_compute_key(secret, pub_key, pdhctx->dh);
    if (ret <= 0)
        return 0;

    *secretlen = ret;
    return 1;
}

static int dh_X9_42_kdf_derive(void *vpdhctx, unsigned char *secret,
                               size_t *secretlen, size_t outlen)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    unsigned char *stmp = NULL;
    size_t stmplen;
    int ret = 0;

    if (secret == NULL) {
        *secretlen = pdhctx->kdf_outlen;
        return 1;
    }

    if (pdhctx->kdf_outlen > outlen) {
        ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
        return 0;
    }
    if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
        return 0;
    if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
        return 0;
    if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
        goto err;

    /* Do KDF stuff */
    if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
        if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
                                    stmp, stmplen,
                                    pdhctx->kdf_cekalg,
                                    pdhctx->kdf_ukm,
                                    pdhctx->kdf_ukmlen,
                                    pdhctx->kdf_md,
                                    pdhctx->libctx, NULL))
            goto err;
    }
    *secretlen = pdhctx->kdf_outlen;
    ret = 1;
err:
    OPENSSL_secure_clear_free(stmp, stmplen);
    return ret;
}

static int dh_derive(void *vpdhctx, unsigned char *secret,
                     size_t *psecretlen, size_t outlen)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    if (!ossl_prov_is_running())
        return 0;

    switch (pdhctx->kdf_type) {
        case PROV_DH_KDF_NONE:
            return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
                                   pdhctx->pad);
        case PROV_DH_KDF_X9_42_ASN1:
            return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
        default:
            break;
    }
    return 0;
}

static void dh_freectx(void *vpdhctx)
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;

    OPENSSL_free(pdhctx->kdf_cekalg);
    DH_free(pdhctx->dh);
    DH_free(pdhctx->dhpeer);
    EVP_MD_free(pdhctx->kdf_md);
    OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);

    OPENSSL_free(pdhctx);
}

static void *dh_dupctx(void *vpdhctx)
{
    PROV_DH_CTX *srcctx = (PROV_DH_CTX *)vpdhctx;
    PROV_DH_CTX *dstctx;

    if (!ossl_prov_is_running())
        return NULL;

    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
    if (dstctx == NULL)
        return NULL;

    *dstctx = *srcctx;
    dstctx->dh = NULL;
    dstctx->dhpeer = NULL;
    dstctx->kdf_md = NULL;
    dstctx->kdf_ukm = NULL;
    dstctx->kdf_cekalg = NULL;

    if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
        goto err;
    else
        dstctx->dh = srcctx->dh;

    if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
        goto err;
    else
        dstctx->dhpeer = srcctx->dhpeer;

    if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
        goto err;
    else
        dstctx->kdf_md = srcctx->kdf_md;

    /* Duplicate UKM data if present */
    if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
        dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
                                         srcctx->kdf_ukmlen);
        if (dstctx->kdf_ukm == NULL)
            goto err;
    }

    if (srcctx->kdf_cekalg != NULL) {
        dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
        if (dstctx->kdf_cekalg == NULL)
            goto err;
    }

    return dstctx;
err:
    dh_freectx(dstctx);
    return NULL;
}

static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    const OSSL_PARAM *p;
    unsigned int pad;
    char name[80] = { '\0' }; /* should be big enough */
    char *str = NULL;

    if (pdhctx == NULL)
        return 0;
    if (ossl_param_is_empty(params))
        return 1;

    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE0, params,
                                     OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
        return  0;
    if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE1, params,
                                     OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
        return  0;

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
    if (p != NULL) {
        str = name;
        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
            return 0;

        if (name[0] == '\0')
            pdhctx->kdf_type = PROV_DH_KDF_NONE;
        else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
            pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
        else
            return 0;
    }
    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
    if (p != NULL) {
        char mdprops[80] = { '\0' }; /* should be big enough */

        str = name;
        if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
            return 0;

        str = mdprops;
        p = OSSL_PARAM_locate_const(params,
                                    OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);

        if (p != NULL) {
            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
                return 0;
        }

        EVP_MD_free(pdhctx->kdf_md);
        pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
        if (pdhctx->kdf_md == NULL)
            return 0;
        /* XOF digests are not allowed */
        if (EVP_MD_xof(pdhctx->kdf_md)) {
            ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
            return 0;
        }
#ifdef FIPS_MODULE
        if (!digest_check(pdhctx, pdhctx->kdf_md)) {
            EVP_MD_free(pdhctx->kdf_md);
            pdhctx->kdf_md = NULL;
            return 0;
        }
#endif
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
    if (p != NULL) {
        size_t outlen;

        if (!OSSL_PARAM_get_size_t(p, &outlen))
            return 0;
        pdhctx->kdf_outlen = outlen;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
    if (p != NULL) {
        void *tmp_ukm = NULL;
        size_t tmp_ukmlen;

        OPENSSL_free(pdhctx->kdf_ukm);
        pdhctx->kdf_ukm = NULL;
        pdhctx->kdf_ukmlen = 0;
        /* ukm is an optional field so it can be NULL */
        if (p->data != NULL && p->data_size != 0) {
            if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
                return 0;
            pdhctx->kdf_ukm = tmp_ukm;
            pdhctx->kdf_ukmlen = tmp_ukmlen;
        }
    }

    p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
    if (p != NULL) {
        if (!OSSL_PARAM_get_uint(p, &pad))
            return 0;
        pdhctx->pad = pad ? 1 : 0;
    }

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
    if (p != NULL) {
        str = name;

        OPENSSL_free(pdhctx->kdf_cekalg);
        pdhctx->kdf_cekalg = NULL;
        if (p->data != NULL && p->data_size != 0) {
            if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
                return 0;
            pdhctx->kdf_cekalg = OPENSSL_strdup(name);
            if (pdhctx->kdf_cekalg == NULL)
                return 0;
        }
    }
    return 1;
}

static const OSSL_PARAM known_settable_ctx_params[] = {
    OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
    OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
    OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK)
    OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK)
    OSSL_PARAM_END
};

static const OSSL_PARAM *dh_settable_ctx_params(ossl_unused void *vpdhctx,
                                                ossl_unused void *provctx)
{
    return known_settable_ctx_params;
}

static const OSSL_PARAM known_gettable_ctx_params[] = {
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
    OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
    OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
                    NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
    OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
    OSSL_PARAM_END
};

static const OSSL_PARAM *dh_gettable_ctx_params(ossl_unused void *vpdhctx,
                                                ossl_unused void *provctx)
{
    return known_gettable_ctx_params;
}

static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
{
    PROV_DH_CTX *pdhctx = (PROV_DH_CTX *)vpdhctx;
    OSSL_PARAM *p;

    if (pdhctx == NULL)
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
    if (p != NULL) {
        const char *kdf_type = NULL;

        switch (pdhctx->kdf_type) {
            case PROV_DH_KDF_NONE:
                kdf_type = "";
                break;
            case PROV_DH_KDF_X9_42_ASN1:
                kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
                break;
            default:
                return 0;
        }

        if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
            return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
    if (p != NULL
            && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
                                           ? ""
                                           : EVP_MD_get0_name(pdhctx->kdf_md))) {
        return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
    if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
    if (p != NULL
        && !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
    if (p != NULL
            && !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
                                           ? "" :  pdhctx->kdf_cekalg))
        return 0;
    if (!OSSL_FIPS_IND_GET_CTX_PARAM(pdhctx, params))
        return 0;
    return 1;
}

const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
    { OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
    { OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
    { OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
    { OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
    { OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
    { OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
    { OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
    { OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
      (void (*)(void))dh_settable_ctx_params },
    { OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
    { OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
      (void (*)(void))dh_gettable_ctx_params },
    OSSL_DISPATCH_END
};

Coverage Report

Created: 2025-06-13 06:57

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2019-2024 The OpenSSL Project Authors. All Rights Reserved.
3		*
4		* Licensed under the Apache License 2.0 (the "License"). You may not use
5		* this file except in compliance with the License. You can obtain a copy
6		* in the file LICENSE in the source distribution or at
7		* https://www.openssl.org/source/license.html
8		*/
9
10		/*
11		* DH low level APIs are deprecated for public use, but still ok for
12		* internal use.
13		*/
14		#include "internal/deprecated.h"
15
16		#include <string.h>
17		#include <openssl/crypto.h>
18		#include <openssl/core_dispatch.h>
19		#include <openssl/core_names.h>
20		#include <openssl/dh.h>
21		#include <openssl/err.h>
22		#include <openssl/proverr.h>
23		#include <openssl/params.h>
24		#include "prov/providercommon.h"
25		#include "prov/implementations.h"
26		#include "prov/provider_ctx.h"
27		#include "prov/securitycheck.h"
28		#include "crypto/dh.h"
29
30		static OSSL_FUNC_keyexch_newctx_fn dh_newctx;
31		static OSSL_FUNC_keyexch_init_fn dh_init;
32		static OSSL_FUNC_keyexch_set_peer_fn dh_set_peer;
33		static OSSL_FUNC_keyexch_derive_fn dh_derive;
34		static OSSL_FUNC_keyexch_freectx_fn dh_freectx;
35		static OSSL_FUNC_keyexch_dupctx_fn dh_dupctx;
36		static OSSL_FUNC_keyexch_set_ctx_params_fn dh_set_ctx_params;
37		static OSSL_FUNC_keyexch_settable_ctx_params_fn dh_settable_ctx_params;
38		static OSSL_FUNC_keyexch_get_ctx_params_fn dh_get_ctx_params;
39		static OSSL_FUNC_keyexch_gettable_ctx_params_fn dh_gettable_ctx_params;
40
41		/*
42		* This type is only really used to handle some legacy related functionality.
43		* If you need to use other KDF's (such as SSKDF) just use PROV_DH_KDF_NONE
44		* here and then create and run a KDF after the key is derived.
45		* Note that X942 has 2 variants of key derivation:
46		* (1) DH_KDF_X9_42_ASN1 - which contains an ANS1 encoded object that has
47		* the counter embedded in it.
48		* (2) DH_KDF_X941_CONCAT - which is the same as ECDH_X963_KDF (which can be
49		* done by creating a "X963KDF".
50		*/
51		enum kdf_type {
52		PROV_DH_KDF_NONE = 0,
53		PROV_DH_KDF_X9_42_ASN1
54		};
55
56		/*
57		* What's passed as an actual key is defined by the KEYMGMT interface.
58		* We happen to know that our KEYMGMT simply passes DH structures, so
59		* we use that here too.
60		*/
61
62		typedef struct {
63		OSSL_LIB_CTX *libctx;
64		DH *dh;
65		DH *dhpeer;
66		unsigned int pad : 1;
67
68		/* DH KDF */
69		/* KDF (if any) to use for DH */
70		enum kdf_type kdf_type;
71		/* Message digest to use for key derivation */
72		EVP_MD *kdf_md;
73		/* User key material */
74		unsigned char *kdf_ukm;
75		size_t kdf_ukmlen;
76		/* KDF output length */
77		size_t kdf_outlen;
78		char *kdf_cekalg;
79		OSSL_FIPS_IND_DECLARE
80		} PROV_DH_CTX;
81
82		static void dh_newctx(void provctx)
83	0	{
84	0	PROV_DH_CTX *pdhctx;
85
86	0	if (!ossl_prov_is_running())
87	0	return NULL;
88
89	0	pdhctx = OPENSSL_zalloc(sizeof(PROV_DH_CTX));
90	0	if (pdhctx == NULL)
91	0	return NULL;
92	0	OSSL_FIPS_IND_INIT(pdhctx)
93	0	pdhctx->libctx = PROV_LIBCTX_OF(provctx);
94	0	pdhctx->kdf_type = PROV_DH_KDF_NONE;
95	0	return pdhctx;
96	0	}
97
98		#ifdef FIPS_MODULE
99		static int dh_check_key(PROV_DH_CTX *ctx)
100		{
101		int key_approved = ossl_dh_check_key(ctx->dh);
102
103		if (!key_approved) {
104		if (!OSSL_FIPS_IND_ON_UNAPPROVED(ctx, OSSL_FIPS_IND_SETTABLE0,
105		ctx->libctx, "DH Init", "DH Key",
106		ossl_fips_config_securitycheck_enabled)) {
107		ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
108		return 0;
109		}
110		}
111		return 1;
112		}
113
114		static int digest_check(PROV_DH_CTX ctx, const EVP_MD md)
115		{
116		return ossl_fips_ind_digest_exch_check(OSSL_FIPS_IND_GET(ctx),
117		OSSL_FIPS_IND_SETTABLE1, ctx->libctx,
118		md, "DH Set Ctx");
119		}
120		#endif
121
122		static int dh_init(void vpdhctx, void vdh, const OSSL_PARAM params[])
123	0	{
124	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
125
126	0	if (!ossl_prov_is_running()
127	0	\|\| pdhctx == NULL
128	0	\|\| vdh == NULL
129	0	\|\| !DH_up_ref(vdh))
130	0	return 0;
131	0	DH_free(pdhctx->dh);
132	0	pdhctx->dh = vdh;
133	0	pdhctx->kdf_type = PROV_DH_KDF_NONE;
134
135	0	OSSL_FIPS_IND_SET_APPROVED(pdhctx)
136	0	if (!dh_set_ctx_params(pdhctx, params))
137	0	return 0;
138		#ifdef FIPS_MODULE
139		if (!dh_check_key(pdhctx))
140		return 0;
141		#endif
142	0	return 1;
143	0	}
144
145		/* The 2 parties must share the same domain parameters */
146		static int dh_match_params(DH priv, DH peer)
147	0	{
148	0	int ret;
149	0	FFC_PARAMS *dhparams_priv = ossl_dh_get0_params(priv);
150	0	FFC_PARAMS *dhparams_peer = ossl_dh_get0_params(peer);
151
152	0	ret = dhparams_priv != NULL
153	0	&& dhparams_peer != NULL
154	0	&& ossl_ffc_params_cmp(dhparams_priv, dhparams_peer, 1);
155	0	if (!ret)
156	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISMATCHING_DOMAIN_PARAMETERS);
157	0	return ret;
158	0	}
159
160		static int dh_set_peer(void vpdhctx, void vdh)
161	0	{
162	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
163
164	0	if (!ossl_prov_is_running()
165	0	\|\| pdhctx == NULL
166	0	\|\| vdh == NULL
167	0	\|\| !dh_match_params(vdh, pdhctx->dh)
168	0	\|\| !DH_up_ref(vdh))
169	0	return 0;
170	0	DH_free(pdhctx->dhpeer);
171	0	pdhctx->dhpeer = vdh;
172	0	return 1;
173	0	}
174
175		static int dh_plain_derive(void *vpdhctx,
176		unsigned char secret, size_t secretlen,
177		size_t outlen, unsigned int pad)
178	0	{
179	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
180	0	int ret;
181	0	size_t dhsize;
182	0	const BIGNUM *pub_key = NULL;
183
184	0	if (pdhctx->dh == NULL \|\| pdhctx->dhpeer == NULL) {
185	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
186	0	return 0;
187	0	}
188
189	0	dhsize = (size_t)DH_size(pdhctx->dh);
190	0	if (secret == NULL) {
191	0	*secretlen = dhsize;
192	0	return 1;
193	0	}
194	0	if (outlen < dhsize) {
195	0	ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
196	0	return 0;
197	0	}
198
199	0	DH_get0_key(pdhctx->dhpeer, &pub_key, NULL);
200	0	if (pad)
201	0	ret = DH_compute_key_padded(secret, pub_key, pdhctx->dh);
202	0	else
203	0	ret = DH_compute_key(secret, pub_key, pdhctx->dh);
204	0	if (ret <= 0)
205	0	return 0;
206
207	0	*secretlen = ret;
208	0	return 1;
209	0	}
210
211		static int dh_X9_42_kdf_derive(void vpdhctx, unsigned char secret,
212		size_t *secretlen, size_t outlen)
213	0	{
214	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
215	0	unsigned char *stmp = NULL;
216	0	size_t stmplen;
217	0	int ret = 0;
218
219	0	if (secret == NULL) {
220	0	*secretlen = pdhctx->kdf_outlen;
221	0	return 1;
222	0	}
223
224	0	if (pdhctx->kdf_outlen > outlen) {
225	0	ERR_raise(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL);
226	0	return 0;
227	0	}
228	0	if (!dh_plain_derive(pdhctx, NULL, &stmplen, 0, 1))
229	0	return 0;
230	0	if ((stmp = OPENSSL_secure_malloc(stmplen)) == NULL)
231	0	return 0;
232	0	if (!dh_plain_derive(pdhctx, stmp, &stmplen, stmplen, 1))
233	0	goto err;
234
235		/* Do KDF stuff */
236	0	if (pdhctx->kdf_type == PROV_DH_KDF_X9_42_ASN1) {
237	0	if (!ossl_dh_kdf_X9_42_asn1(secret, pdhctx->kdf_outlen,
238	0	stmp, stmplen,
239	0	pdhctx->kdf_cekalg,
240	0	pdhctx->kdf_ukm,
241	0	pdhctx->kdf_ukmlen,
242	0	pdhctx->kdf_md,
243	0	pdhctx->libctx, NULL))
244	0	goto err;
245	0	}
246	0	*secretlen = pdhctx->kdf_outlen;
247	0	ret = 1;
248	0	err:
249	0	OPENSSL_secure_clear_free(stmp, stmplen);
250	0	return ret;
251	0	}
252
253		static int dh_derive(void vpdhctx, unsigned char secret,
254		size_t *psecretlen, size_t outlen)
255	0	{
256	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
257
258	0	if (!ossl_prov_is_running())
259	0	return 0;
260
261	0	switch (pdhctx->kdf_type) {
262	0	case PROV_DH_KDF_NONE:
263	0	return dh_plain_derive(pdhctx, secret, psecretlen, outlen,
264	0	pdhctx->pad);
265	0	case PROV_DH_KDF_X9_42_ASN1:
266	0	return dh_X9_42_kdf_derive(pdhctx, secret, psecretlen, outlen);
267	0	default:
268	0	break;
269	0	}
270	0	return 0;
271	0	}
272
273		static void dh_freectx(void *vpdhctx)
274	0	{
275	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
276
277	0	OPENSSL_free(pdhctx->kdf_cekalg);
278	0	DH_free(pdhctx->dh);
279	0	DH_free(pdhctx->dhpeer);
280	0	EVP_MD_free(pdhctx->kdf_md);
281	0	OPENSSL_clear_free(pdhctx->kdf_ukm, pdhctx->kdf_ukmlen);
282
283	0	OPENSSL_free(pdhctx);
284	0	}
285
286		static void dh_dupctx(void vpdhctx)
287	0	{
288	0	PROV_DH_CTX srcctx = (PROV_DH_CTX )vpdhctx;
289	0	PROV_DH_CTX *dstctx;
290
291	0	if (!ossl_prov_is_running())
292	0	return NULL;
293
294	0	dstctx = OPENSSL_zalloc(sizeof(*srcctx));
295	0	if (dstctx == NULL)
296	0	return NULL;
297
298	0	dstctx = srcctx;
299	0	dstctx->dh = NULL;
300	0	dstctx->dhpeer = NULL;
301	0	dstctx->kdf_md = NULL;
302	0	dstctx->kdf_ukm = NULL;
303	0	dstctx->kdf_cekalg = NULL;
304
305	0	if (srcctx->dh != NULL && !DH_up_ref(srcctx->dh))
306	0	goto err;
307	0	else
308	0	dstctx->dh = srcctx->dh;
309
310	0	if (srcctx->dhpeer != NULL && !DH_up_ref(srcctx->dhpeer))
311	0	goto err;
312	0	else
313	0	dstctx->dhpeer = srcctx->dhpeer;
314
315	0	if (srcctx->kdf_md != NULL && !EVP_MD_up_ref(srcctx->kdf_md))
316	0	goto err;
317	0	else
318	0	dstctx->kdf_md = srcctx->kdf_md;
319
320		/* Duplicate UKM data if present */
321	0	if (srcctx->kdf_ukm != NULL && srcctx->kdf_ukmlen > 0) {
322	0	dstctx->kdf_ukm = OPENSSL_memdup(srcctx->kdf_ukm,
323	0	srcctx->kdf_ukmlen);
324	0	if (dstctx->kdf_ukm == NULL)
325	0	goto err;
326	0	}
327
328	0	if (srcctx->kdf_cekalg != NULL) {
329	0	dstctx->kdf_cekalg = OPENSSL_strdup(srcctx->kdf_cekalg);
330	0	if (dstctx->kdf_cekalg == NULL)
331	0	goto err;
332	0	}
333
334	0	return dstctx;
335	0	err:
336	0	dh_freectx(dstctx);
337	0	return NULL;
338	0	}
339
340		static int dh_set_ctx_params(void *vpdhctx, const OSSL_PARAM params[])
341	0	{
342	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
343	0	const OSSL_PARAM *p;
344	0	unsigned int pad;
345	0	char name[80] = { '\0' }; /* should be big enough */
346	0	char *str = NULL;
347
348	0	if (pdhctx == NULL)
349	0	return 0;
350	0	if (ossl_param_is_empty(params))
351	0	return 1;
352
353	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE0, params,
354	0	OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK))
355	0	return 0;
356	0	if (!OSSL_FIPS_IND_SET_CTX_PARAM(pdhctx, OSSL_FIPS_IND_SETTABLE1, params,
357	0	OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK))
358	0	return 0;
359
360	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
361	0	if (p != NULL) {
362	0	str = name;
363	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
364	0	return 0;
365
366	0	if (name[0] == '\0')
367	0	pdhctx->kdf_type = PROV_DH_KDF_NONE;
368	0	else if (strcmp(name, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
369	0	pdhctx->kdf_type = PROV_DH_KDF_X9_42_ASN1;
370	0	else
371	0	return 0;
372	0	}
373	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
374	0	if (p != NULL) {
375	0	char mdprops[80] = { '\0' }; /* should be big enough */
376
377	0	str = name;
378	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
379	0	return 0;
380
381	0	str = mdprops;
382	0	p = OSSL_PARAM_locate_const(params,
383	0	OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS);
384
385	0	if (p != NULL) {
386	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(mdprops)))
387	0	return 0;
388	0	}
389
390	0	EVP_MD_free(pdhctx->kdf_md);
391	0	pdhctx->kdf_md = EVP_MD_fetch(pdhctx->libctx, name, mdprops);
392	0	if (pdhctx->kdf_md == NULL)
393	0	return 0;
394		/* XOF digests are not allowed */
395	0	if (EVP_MD_xof(pdhctx->kdf_md)) {
396	0	ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
397	0	return 0;
398	0	}
399		#ifdef FIPS_MODULE
400		if (!digest_check(pdhctx, pdhctx->kdf_md)) {
401		EVP_MD_free(pdhctx->kdf_md);
402		pdhctx->kdf_md = NULL;
403		return 0;
404		}
405		#endif
406	0	}
407
408	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
409	0	if (p != NULL) {
410	0	size_t outlen;
411
412	0	if (!OSSL_PARAM_get_size_t(p, &outlen))
413	0	return 0;
414	0	pdhctx->kdf_outlen = outlen;
415	0	}
416
417	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
418	0	if (p != NULL) {
419	0	void *tmp_ukm = NULL;
420	0	size_t tmp_ukmlen;
421
422	0	OPENSSL_free(pdhctx->kdf_ukm);
423	0	pdhctx->kdf_ukm = NULL;
424	0	pdhctx->kdf_ukmlen = 0;
425		/* ukm is an optional field so it can be NULL */
426	0	if (p->data != NULL && p->data_size != 0) {
427	0	if (!OSSL_PARAM_get_octet_string(p, &tmp_ukm, 0, &tmp_ukmlen))
428	0	return 0;
429	0	pdhctx->kdf_ukm = tmp_ukm;
430	0	pdhctx->kdf_ukmlen = tmp_ukmlen;
431	0	}
432	0	}
433
434	0	p = OSSL_PARAM_locate_const(params, OSSL_EXCHANGE_PARAM_PAD);
435	0	if (p != NULL) {
436	0	if (!OSSL_PARAM_get_uint(p, &pad))
437	0	return 0;
438	0	pdhctx->pad = pad ? 1 : 0;
439	0	}
440
441	0	p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_CEK_ALG);
442	0	if (p != NULL) {
443	0	str = name;
444
445	0	OPENSSL_free(pdhctx->kdf_cekalg);
446	0	pdhctx->kdf_cekalg = NULL;
447	0	if (p->data != NULL && p->data_size != 0) {
448	0	if (!OSSL_PARAM_get_utf8_string(p, &str, sizeof(name)))
449	0	return 0;
450	0	pdhctx->kdf_cekalg = OPENSSL_strdup(name);
451	0	if (pdhctx->kdf_cekalg == NULL)
452	0	return 0;
453	0	}
454	0	}
455	0	return 1;
456	0	}
457
458		static const OSSL_PARAM known_settable_ctx_params[] = {
459		OSSL_PARAM_int(OSSL_EXCHANGE_PARAM_PAD, NULL),
460		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
461		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
462		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST_PROPS, NULL, 0),
463		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
464		OSSL_PARAM_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM, NULL, 0),
465		OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
466		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_KEY_CHECK)
467		OSSL_FIPS_IND_SETTABLE_CTX_PARAM(OSSL_EXCHANGE_PARAM_FIPS_DIGEST_CHECK)
468		OSSL_PARAM_END
469		};
470
471		static const OSSL_PARAM dh_settable_ctx_params(ossl_unused void vpdhctx,
472		ossl_unused void *provctx)
473	0	{
474	0	return known_settable_ctx_params;
475	0	}
476
477		static const OSSL_PARAM known_gettable_ctx_params[] = {
478		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE, NULL, 0),
479		OSSL_PARAM_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST, NULL, 0),
480		OSSL_PARAM_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN, NULL),
481		OSSL_PARAM_DEFN(OSSL_EXCHANGE_PARAM_KDF_UKM, OSSL_PARAM_OCTET_PTR,
482		NULL, 0),
483		OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CEK_ALG, NULL, 0),
484		OSSL_FIPS_IND_GETTABLE_CTX_PARAM()
485		OSSL_PARAM_END
486		};
487
488		static const OSSL_PARAM dh_gettable_ctx_params(ossl_unused void vpdhctx,
489		ossl_unused void *provctx)
490	0	{
491	0	return known_gettable_ctx_params;
492	0	}
493
494		static int dh_get_ctx_params(void *vpdhctx, OSSL_PARAM params[])
495	0	{
496	0	PROV_DH_CTX pdhctx = (PROV_DH_CTX )vpdhctx;
497	0	OSSL_PARAM *p;
498
499	0	if (pdhctx == NULL)
500	0	return 0;
501
502	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_TYPE);
503	0	if (p != NULL) {
504	0	const char *kdf_type = NULL;
505
506	0	switch (pdhctx->kdf_type) {
507	0	case PROV_DH_KDF_NONE:
508	0	kdf_type = "";
509	0	break;
510	0	case PROV_DH_KDF_X9_42_ASN1:
511	0	kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
512	0	break;
513	0	default:
514	0	return 0;
515	0	}
516
517	0	if (!OSSL_PARAM_set_utf8_string(p, kdf_type))
518	0	return 0;
519	0	}
520
521	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_DIGEST);
522	0	if (p != NULL
523	0	&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_md == NULL
524	0	? ""
525	0	: EVP_MD_get0_name(pdhctx->kdf_md))) {
526	0	return 0;
527	0	}
528
529	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_OUTLEN);
530	0	if (p != NULL && !OSSL_PARAM_set_size_t(p, pdhctx->kdf_outlen))
531	0	return 0;
532
533	0	p = OSSL_PARAM_locate(params, OSSL_EXCHANGE_PARAM_KDF_UKM);
534	0	if (p != NULL
535	0	&& !OSSL_PARAM_set_octet_ptr(p, pdhctx->kdf_ukm, pdhctx->kdf_ukmlen))
536	0	return 0;
537
538	0	p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_CEK_ALG);
539	0	if (p != NULL
540	0	&& !OSSL_PARAM_set_utf8_string(p, pdhctx->kdf_cekalg == NULL
541	0	? "" : pdhctx->kdf_cekalg))
542	0	return 0;
543	0	if (!OSSL_FIPS_IND_GET_CTX_PARAM(pdhctx, params))
544	0	return 0;
545	0	return 1;
546	0	}
547
548		const OSSL_DISPATCH ossl_dh_keyexch_functions[] = {
549		{ OSSL_FUNC_KEYEXCH_NEWCTX, (void (*)(void))dh_newctx },
550		{ OSSL_FUNC_KEYEXCH_INIT, (void (*)(void))dh_init },
551		{ OSSL_FUNC_KEYEXCH_DERIVE, (void (*)(void))dh_derive },
552		{ OSSL_FUNC_KEYEXCH_SET_PEER, (void (*)(void))dh_set_peer },
553		{ OSSL_FUNC_KEYEXCH_FREECTX, (void (*)(void))dh_freectx },
554		{ OSSL_FUNC_KEYEXCH_DUPCTX, (void (*)(void))dh_dupctx },
555		{ OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS, (void (*)(void))dh_set_ctx_params },
556		{ OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS,
557		(void (*)(void))dh_settable_ctx_params },
558		{ OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS, (void (*)(void))dh_get_ctx_params },
559		{ OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS,
560		(void (*)(void))dh_gettable_ctx_params },
561		OSSL_DISPATCH_END
562		};