/*

 * Copyright 2019-2026 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

 */

#include <openssl/crypto.h>

#include <openssl/evp.h>

#include <openssl/err.h>

#include "internal/cryptlib.h"

#include "internal/refcount.h"

#include "internal/provider.h"

#include "internal/core.h"

#include "internal/numbers.h" /* includes SIZE_MAX */

#include "crypto/evp.h"

#include "evp_local.h"

static EVP_KEYEXCH *evp_keyexch_new(OSSL_PROVIDER *prov)

{

    EVP_KEYEXCH *exchange = OPENSSL_zalloc(sizeof(EVP_KEYEXCH));

    if (exchange == NULL)

        return NULL;

    if (!CRYPTO_NEW_REF(&exchange->refcnt, 1)) {

        OPENSSL_free(exchange);

        return NULL;

    }

    exchange->prov = prov;

    ossl_provider_up_ref(prov);

    return exchange;

}

static void *evp_keyexch_from_algorithm(int name_id,

    const OSSL_ALGORITHM *algodef,

    OSSL_PROVIDER *prov)

{

    const OSSL_DISPATCH *fns = algodef->implementation;

    EVP_KEYEXCH *exchange = NULL;

    int fncnt = 0, sparamfncnt = 0, gparamfncnt = 0;

    if ((exchange = evp_keyexch_new(prov)) == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_EVP_LIB);

        goto err;

    }

    exchange->name_id = name_id;

    if ((exchange->type_name = ossl_algorithm_get1_first_name(algodef)) == NULL)

        goto err;

    exchange->description = algodef->algorithm_description;

    for (; fns->function_id != 0; fns++) {

        switch (fns->function_id) {

        case OSSL_FUNC_KEYEXCH_NEWCTX:

            if (exchange->newctx != NULL)

                break;

            exchange->newctx = OSSL_FUNC_keyexch_newctx(fns);

            fncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_INIT:

            if (exchange->init != NULL)

                break;

            exchange->init = OSSL_FUNC_keyexch_init(fns);

            fncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_SET_PEER:

            if (exchange->set_peer != NULL)

                break;

            exchange->set_peer = OSSL_FUNC_keyexch_set_peer(fns);

            break;

        case OSSL_FUNC_KEYEXCH_DERIVE:

            if (exchange->derive != NULL)

                break;

            exchange->derive = OSSL_FUNC_keyexch_derive(fns);

            fncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_FREECTX:

            if (exchange->freectx != NULL)

                break;

            exchange->freectx = OSSL_FUNC_keyexch_freectx(fns);

            fncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_DUPCTX:

            if (exchange->dupctx != NULL)

                break;

            exchange->dupctx = OSSL_FUNC_keyexch_dupctx(fns);

            break;

        case OSSL_FUNC_KEYEXCH_GET_CTX_PARAMS:

            if (exchange->get_ctx_params != NULL)

                break;

            exchange->get_ctx_params = OSSL_FUNC_keyexch_get_ctx_params(fns);

            gparamfncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_GETTABLE_CTX_PARAMS:

            if (exchange->gettable_ctx_params != NULL)

                break;

            exchange->gettable_ctx_params

                = OSSL_FUNC_keyexch_gettable_ctx_params(fns);

            gparamfncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_SET_CTX_PARAMS:

            if (exchange->set_ctx_params != NULL)

                break;

            exchange->set_ctx_params = OSSL_FUNC_keyexch_set_ctx_params(fns);

            sparamfncnt++;

            break;

        case OSSL_FUNC_KEYEXCH_SETTABLE_CTX_PARAMS:

            if (exchange->settable_ctx_params != NULL)

                break;

            exchange->settable_ctx_params

                = OSSL_FUNC_keyexch_settable_ctx_params(fns);

            sparamfncnt++;

            break;

        }

    }

    if (fncnt != 4

        || (gparamfncnt != 0 && gparamfncnt != 2)

        || (sparamfncnt != 0 && sparamfncnt != 2)) {

        /*

         * In order to be a consistent set of functions we must have at least

         * a complete set of "exchange" functions: init, derive, newctx,

         * and freectx. The set_ctx_params and settable_ctx_params functions are

         * optional, but if one of them is present then the other one must also

         * be present. Same goes for get_ctx_params and gettable_ctx_params.

         * The dupctx and set_peer functions are optional.

         */

        ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_PROVIDER_FUNCTIONS);

        goto err;

    }

    return exchange;

err:

    EVP_KEYEXCH_free(exchange);

    return NULL;

}

void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange)

{

    int i;

    if (exchange == NULL)

        return;

    CRYPTO_DOWN_REF(&exchange->refcnt, &i);

    if (i > 0)

        return;

    OPENSSL_free(exchange->type_name);

    ossl_provider_free(exchange->prov);

    CRYPTO_FREE_REF(&exchange->refcnt);

    OPENSSL_free(exchange);

}

int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange)

{

    int ref = 0;

    CRYPTO_UP_REF(&exchange->refcnt, &ref);

    return 1;

}

OSSL_PROVIDER *EVP_KEYEXCH_get0_provider(const EVP_KEYEXCH *exchange)

{

    return exchange->prov;

}

EVP_KEYEXCH *EVP_KEYEXCH_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,

    const char *properties)

{

    return evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,

        evp_keyexch_from_algorithm,

        (int (*)(void *))EVP_KEYEXCH_up_ref,

        (void (*)(void *))EVP_KEYEXCH_free);

}

EVP_KEYEXCH *evp_keyexch_fetch_from_prov(OSSL_PROVIDER *prov,

    const char *algorithm,

    const char *properties)

{

    return evp_generic_fetch_from_prov(prov, OSSL_OP_KEYEXCH,

        algorithm, properties,

        evp_keyexch_from_algorithm,

        (int (*)(void *))EVP_KEYEXCH_up_ref,

        (void (*)(void *))EVP_KEYEXCH_free);

}

int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx)

{

    return EVP_PKEY_derive_init_ex(ctx, NULL);

}

int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[])

{

    int ret;

    void *provkey = NULL;

    EVP_KEYEXCH *exchange = NULL;

    EVP_KEYMGMT *tmp_keymgmt = NULL;

    const OSSL_PROVIDER *tmp_prov = NULL;

    const char *supported_exch = NULL;

    int iter;

    if (ctx == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_PASSED_NULL_PARAMETER);

        return -2;

    }

    evp_pkey_ctx_free_old_ops(ctx);

    ctx->operation = EVP_PKEY_OP_DERIVE;

    ERR_set_mark();

    if (evp_pkey_ctx_is_legacy(ctx))

        goto legacy;

    /*

     * Some algorithms (e.g. legacy KDFs) don't have a pkey - so we create

     * a blank one.

     */

    if (ctx->pkey == NULL) {

        EVP_PKEY *pkey = EVP_PKEY_new();

        if (pkey == NULL

            || !EVP_PKEY_set_type_by_keymgmt(pkey, ctx->keymgmt)

            || (pkey->keydata = evp_keymgmt_newdata(ctx->keymgmt)) == NULL) {

            ERR_clear_last_mark();

            EVP_PKEY_free(pkey);

            ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

            goto err;

        }

        ctx->pkey = pkey;

    }

    /*

     * Try to derive the supported exch from |ctx->keymgmt|.

     */

    if (!ossl_assert(ctx->pkey->keymgmt == NULL

            || ctx->pkey->keymgmt == ctx->keymgmt)) {

        ERR_clear_last_mark();

        ERR_raise(ERR_LIB_EVP, ERR_R_INTERNAL_ERROR);

        goto err;

    }

    supported_exch = evp_keymgmt_util_query_operation_name(ctx->keymgmt,

        OSSL_OP_KEYEXCH);

    if (supported_exch == NULL) {

        ERR_clear_last_mark();

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    /*

     * We perform two iterations:

     *

     * 1.  Do the normal exchange fetch, using the fetching data given by

     *     the EVP_PKEY_CTX.

     * 2.  Do the provider specific exchange fetch, from the same provider

     *     as |ctx->keymgmt|

     *

     * We then try to fetch the keymgmt from the same provider as the

     * exchange, and try to export |ctx->pkey| to that keymgmt (when

     * this keymgmt happens to be the same as |ctx->keymgmt|, the export

     * is a no-op, but we call it anyway to not complicate the code even

     * more).

     * If the export call succeeds (returns a non-NULL provider key pointer),

     * we're done and can perform the operation itself.  If not, we perform

     * the second iteration, or jump to legacy.

     */

    for (iter = 1, provkey = NULL; iter < 3 && provkey == NULL; iter++) {

        EVP_KEYMGMT *tmp_keymgmt_tofree = NULL;

        /*

         * If we're on the second iteration, free the results from the first.

         * They are NULL on the first iteration, so no need to check what

         * iteration we're on.

         */

        EVP_KEYEXCH_free(exchange);

        exchange = NULL;

        EVP_KEYMGMT_free(tmp_keymgmt);

        tmp_keymgmt = NULL;

        switch (iter) {

        case 1:

            exchange = EVP_KEYEXCH_fetch(ctx->libctx, supported_exch, ctx->propquery);

            if (exchange != NULL)

                tmp_prov = EVP_KEYEXCH_get0_provider(exchange);

            break;

        case 2:

            tmp_prov = EVP_KEYMGMT_get0_provider(ctx->keymgmt);

            exchange = evp_keyexch_fetch_from_prov((OSSL_PROVIDER *)tmp_prov,

                supported_exch, ctx->propquery);

            if (exchange == NULL)

                goto legacy;

            break;

        }

        if (exchange == NULL)

            continue;

        /*

         * Ensure that the key is provided, either natively, or as a cached

         * export.  We start by fetching the keymgmt with the same name as

         * |ctx->keymgmt|, but from the provider of the exchange method, using

         * the same property query as when fetching the exchange method.

         * With the keymgmt we found (if we did), we try to export |ctx->pkey|

         * to it (evp_pkey_export_to_provider() is smart enough to only actually

         * export it if |tmp_keymgmt| is different from |ctx->pkey|'s keymgmt)

         */

        tmp_keymgmt_tofree = tmp_keymgmt = evp_keymgmt_fetch_from_prov((OSSL_PROVIDER *)tmp_prov,

            EVP_KEYMGMT_get0_name(ctx->keymgmt),

            ctx->propquery);

        if (tmp_keymgmt != NULL)

            provkey = evp_pkey_export_to_provider(ctx->pkey, ctx->libctx,

                &tmp_keymgmt, ctx->propquery);

        if (tmp_keymgmt == NULL)

            EVP_KEYMGMT_free(tmp_keymgmt_tofree);

    }

    if (provkey == NULL) {

        EVP_KEYEXCH_free(exchange);

        goto legacy;

    }

    ERR_pop_to_mark();

    /* No more legacy from here down to legacy: */

    /* A Coverity false positive with up_ref/down_ref and free */

    /* coverity[use_after_free] */

    ctx->op.kex.exchange = exchange;

    /* A Coverity false positive with up_ref/down_ref and free */

    /* coverity[deref_arg] */

    ctx->op.kex.algctx = exchange->newctx(ossl_provider_ctx(exchange->prov));

    if (ctx->op.kex.algctx == NULL) {

        /* The provider key can stay in the cache */

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    ret = exchange->init(ctx->op.kex.algctx, provkey, params);

    EVP_KEYMGMT_free(tmp_keymgmt);

    return ret ? 1 : 0;

err:

    evp_pkey_ctx_free_old_ops(ctx);

    ctx->operation = EVP_PKEY_OP_UNDEFINED;

    EVP_KEYMGMT_free(tmp_keymgmt);

    return 0;

legacy:

    /*

     * If we don't have the full support we need with provided methods,

     * let's go see if legacy does.

     */

    ERR_pop_to_mark();

#ifdef FIPS_MODULE

    return 0;

#else

    if (ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    if (ctx->pmeth->derive_init == NULL)

        return 1;

    ret = ctx->pmeth->derive_init(ctx);

    if (ret <= 0)

        ctx->operation = EVP_PKEY_OP_UNDEFINED;

    EVP_KEYMGMT_free(tmp_keymgmt);

    return ret;

#endif

}

int EVP_PKEY_derive_set_peer_ex(EVP_PKEY_CTX *ctx, EVP_PKEY *peer,

    int validate_peer)

{

    int ret = 0, check;

    void *provkey = NULL;

    EVP_PKEY_CTX *check_ctx = NULL;

    EVP_KEYMGMT *tmp_keymgmt = NULL, *tmp_keymgmt_tofree = NULL;

    if (ctx == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_PASSED_NULL_PARAMETER);

        return -1;

    }

    if (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx) || ctx->op.kex.algctx == NULL)

        goto legacy;

    if (ctx->op.kex.exchange->set_peer == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    if (validate_peer) {

        check_ctx = EVP_PKEY_CTX_new_from_pkey(ctx->libctx, peer, ctx->propquery);

        if (check_ctx == NULL)

            return -1;

        check = EVP_PKEY_public_check(check_ctx);

        EVP_PKEY_CTX_free(check_ctx);

        if (check <= 0)

            return -1;

    }

    /*

     * Ensure that the |peer| is provided, either natively, or as a cached

     * export.  We start by fetching the keymgmt with the same name as

     * |ctx->keymgmt|, but from the provider of the exchange method, using

     * the same property query as when fetching the exchange method.

     * With the keymgmt we found (if we did), we try to export |peer|

     * to it (evp_pkey_export_to_provider() is smart enough to only actually

     * export it if |tmp_keymgmt| is different from |peer|'s keymgmt)

     */

    tmp_keymgmt_tofree = tmp_keymgmt = evp_keymgmt_fetch_from_prov((OSSL_PROVIDER *)

                                                                       EVP_KEYEXCH_get0_provider(ctx->op.kex.exchange),

        EVP_KEYMGMT_get0_name(ctx->keymgmt),

        ctx->propquery);

    if (tmp_keymgmt != NULL)

        /* A Coverity issue with up_ref/down_ref and free */

        /* coverity[pass_freed_arg] */

        provkey = evp_pkey_export_to_provider(peer, ctx->libctx,

            &tmp_keymgmt, ctx->propquery);

    EVP_KEYMGMT_free(tmp_keymgmt_tofree);

    /*

     * If making the key provided wasn't possible, legacy may be able to pick

     * it up

     */

    if (provkey == NULL)

        goto legacy;

    ret = ctx->op.kex.exchange->set_peer(ctx->op.kex.algctx, provkey);

    if (ret <= 0)

        return ret;

    EVP_PKEY_free(ctx->peerkey);

    ctx->peerkey = peer;

    EVP_PKEY_up_ref(peer);

    return 1;

legacy:

#ifdef FIPS_MODULE

    return ret;

#else

    if (ctx->pmeth == NULL

        || !(ctx->pmeth->derive != NULL

            || ctx->pmeth->encrypt != NULL

            || ctx->pmeth->decrypt != NULL)

        || ctx->pmeth->ctrl == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    if (ctx->operation != EVP_PKEY_OP_DERIVE

        && ctx->operation != EVP_PKEY_OP_ENCRYPT

        && ctx->operation != EVP_PKEY_OP_DECRYPT) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_INITIALIZED);

        return -1;

    }

    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 0, peer);

    if (ret <= 0)

        return ret;

    if (ret == 2)

        return 1;

    if (ctx->pkey == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_NO_KEY_SET);

        return -1;

    }

    if (ctx->pkey->type != peer->type) {

        ERR_raise(ERR_LIB_EVP, EVP_R_DIFFERENT_KEY_TYPES);

        return -1;

    }

    /*

     * For clarity.  The error is if parameters in peer are

     * present (!missing) but don't match.  EVP_PKEY_parameters_eq may return

     * 1 (match), 0 (don't match) and -2 (comparison is not defined).  -1

     * (different key types) is impossible here because it is checked earlier.

     * -2 is OK for us here, as well as 1, so we can check for 0 only.

     */

    if (!EVP_PKEY_missing_parameters(peer) && !EVP_PKEY_parameters_eq(ctx->pkey, peer)) {

        ERR_raise(ERR_LIB_EVP, EVP_R_DIFFERENT_PARAMETERS);

        return -1;

    }

    EVP_PKEY_free(ctx->peerkey);

    ctx->peerkey = peer;

    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 1, peer);

    if (ret <= 0) {

        ctx->peerkey = NULL;

        return ret;

    }

    EVP_PKEY_up_ref(peer);

    return 1;

#endif

}

int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer)

{

    return EVP_PKEY_derive_set_peer_ex(ctx, peer, 1);

}

int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *pkeylen)

{

    int ret;

    if (ctx == NULL || pkeylen == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_PASSED_NULL_PARAMETER);

        return -1;

    }

    if (!EVP_PKEY_CTX_IS_DERIVE_OP(ctx)) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_INITIALIZED);

        return -1;

    }

    if (ctx->op.kex.algctx == NULL)

        goto legacy;

    ret = ctx->op.kex.exchange->derive(ctx->op.kex.algctx, key, pkeylen,

        key != NULL ? *pkeylen : 0);

    return ret;

legacy:

    if (ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    M_check_autoarg(ctx, key, pkeylen, EVP_F_EVP_PKEY_DERIVE) return ctx->pmeth->derive(ctx, key, pkeylen);

}

int evp_keyexch_get_number(const EVP_KEYEXCH *keyexch)

{

    return keyexch->name_id;

}

const char *EVP_KEYEXCH_get0_name(const EVP_KEYEXCH *keyexch)

{

    return keyexch->type_name;

}

const char *EVP_KEYEXCH_get0_description(const EVP_KEYEXCH *keyexch)

{

    return keyexch->description;

}

int EVP_KEYEXCH_is_a(const EVP_KEYEXCH *keyexch, const char *name)

{

    return keyexch != NULL

        && evp_is_a(keyexch->prov, keyexch->name_id, NULL, name);

}

void EVP_KEYEXCH_do_all_provided(OSSL_LIB_CTX *libctx,

    void (*fn)(EVP_KEYEXCH *keyexch, void *arg),

    void *arg)

{

    evp_generic_do_all(libctx, OSSL_OP_KEYEXCH,

        (void (*)(void *, void *))fn, arg,

        evp_keyexch_from_algorithm,

        (int (*)(void *))EVP_KEYEXCH_up_ref,

        (void (*)(void *))EVP_KEYEXCH_free);

}

int EVP_KEYEXCH_names_do_all(const EVP_KEYEXCH *keyexch,

    void (*fn)(const char *name, void *data),

    void *data)

{

    if (keyexch->prov != NULL)

        return evp_names_do_all(keyexch->prov, keyexch->name_id, fn, data);

    return 1;

}

const OSSL_PARAM *EVP_KEYEXCH_gettable_ctx_params(const EVP_KEYEXCH *keyexch)

{

    void *provctx;

    if (keyexch == NULL || keyexch->gettable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_KEYEXCH_get0_provider(keyexch));

    return keyexch->gettable_ctx_params(NULL, provctx);

}

const OSSL_PARAM *EVP_KEYEXCH_settable_ctx_params(const EVP_KEYEXCH *keyexch)

{

    void *provctx;

    if (keyexch == NULL || keyexch->settable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_KEYEXCH_get0_provider(keyexch));

    return keyexch->settable_ctx_params(NULL, provctx);

}