/*

 * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright 2019 Red Hat, Inc.

 *

 * 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

 */

/*

 * This implements https://csrc.nist.gov/publications/detail/sp/800-108/final

 * section 5.1 ("counter mode") and section 5.2 ("feedback mode") in both HMAC

 * and CMAC.  That document does not name the KDFs it defines; the name is

 * derived from

 * https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Key-Derivation

 *

 * Note that section 5.3 ("double-pipeline mode") is not implemented, though

 * it would be possible to do so in the future.

 *

 * These versions all assume the counter is used.  It would be relatively

 * straightforward to expose a configuration handle should the need arise.

 *

 * Variable names attempt to match those of SP800-108.

 */

#include <stdarg.h>

#include <stdlib.h>

#include <string.h>

#include <openssl/core_names.h>

#include <openssl/evp.h>

#include <openssl/hmac.h>

#include <openssl/kdf.h>

#include <openssl/params.h>

#include <openssl/proverr.h>

#include "internal/cryptlib.h"

#include "crypto/evp.h"

#include "internal/numbers.h"

#include "internal/endian.h"

#include "prov/implementations.h"

#include "prov/provider_ctx.h"

#include "prov/provider_util.h"

#include "prov/providercommon.h"

#include "e_os.h"

#define ossl_min(a, b) ((a) < (b)) ? (a) : (b)

typedef enum {

    COUNTER = 0,

    FEEDBACK

} kbkdf_mode;

/* Our context structure. */

typedef struct {

    void *provctx;

    kbkdf_mode mode;

    EVP_MAC_CTX *ctx_init;

    /* Names are lowercased versions of those found in SP800-108. */

    unsigned char *ki;

    size_t ki_len;

    unsigned char *label;

    size_t label_len;

    unsigned char *context;

    size_t context_len;

    unsigned char *iv;

    size_t iv_len;

    int use_l;

    int use_separator;

} KBKDF;

/* Definitions needed for typechecking. */

static OSSL_FUNC_kdf_newctx_fn kbkdf_new;

static OSSL_FUNC_kdf_freectx_fn kbkdf_free;

static OSSL_FUNC_kdf_reset_fn kbkdf_reset;

static OSSL_FUNC_kdf_derive_fn kbkdf_derive;

static OSSL_FUNC_kdf_settable_ctx_params_fn kbkdf_settable_ctx_params;

static OSSL_FUNC_kdf_set_ctx_params_fn kbkdf_set_ctx_params;

static OSSL_FUNC_kdf_gettable_ctx_params_fn kbkdf_gettable_ctx_params;

static OSSL_FUNC_kdf_get_ctx_params_fn kbkdf_get_ctx_params;

/* Not all platforms have htobe32(). */

static uint32_t be32(uint32_t host)

{

    uint32_t big = 0;

    DECLARE_IS_ENDIAN;

    if (!IS_LITTLE_ENDIAN)

        return host;

    big |= (host & 0xff000000) >> 24;

    big |= (host & 0x00ff0000) >> 8;

    big |= (host & 0x0000ff00) << 8;

    big |= (host & 0x000000ff) << 24;

    return big;

}

static void init(KBKDF *ctx)

{

    ctx->use_l = 1;

    ctx->use_separator = 1;

}

static void *kbkdf_new(void *provctx)

{

    KBKDF *ctx;

    if (!ossl_prov_is_running())

        return NULL;

    ctx = OPENSSL_zalloc(sizeof(*ctx));

    if (ctx == NULL) {

        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    ctx->provctx = provctx;

    init(ctx);

    return ctx;

}

static void kbkdf_free(void *vctx)

{

    KBKDF *ctx = (KBKDF *)vctx;

    if (ctx != NULL) {

        kbkdf_reset(ctx);

        OPENSSL_free(ctx);

    }

}

static void kbkdf_reset(void *vctx)

{

    KBKDF *ctx = (KBKDF *)vctx;

    void *provctx = ctx->provctx;

    EVP_MAC_CTX_free(ctx->ctx_init);

    OPENSSL_clear_free(ctx->context, ctx->context_len);

    OPENSSL_clear_free(ctx->label, ctx->label_len);

    OPENSSL_clear_free(ctx->ki, ctx->ki_len);

    OPENSSL_clear_free(ctx->iv, ctx->iv_len);

    memset(ctx, 0, sizeof(*ctx));

    ctx->provctx = provctx;

    init(ctx);

}

/* SP800-108 section 5.1 or section 5.2 depending on mode. */

static int derive(EVP_MAC_CTX *ctx_init, kbkdf_mode mode, unsigned char *iv,

                  size_t iv_len, unsigned char *label, size_t label_len,

                  unsigned char *context, size_t context_len,

                  unsigned char *k_i, size_t h, uint32_t l, int has_separator,

                  unsigned char *ko, size_t ko_len)

{

    int ret = 0;

    EVP_MAC_CTX *ctx = NULL;

    size_t written = 0, to_write, k_i_len = iv_len;

    const unsigned char zero = 0;

    uint32_t counter, i;

    /*

     * From SP800-108:

     * The fixed input data is a concatenation of a Label,

     * a separation indicator 0x00, the Context, and L.

     * One or more of these fixed input data fields may be omitted.

     *

     * has_separator == 0 means that the separator is omitted.

     * Passing a value of l == 0 means that L is omitted.

     * The Context and L are omitted automatically if a NULL buffer is passed.

     */

    int has_l = (l != 0);

    /* Setup K(0) for feedback mode. */

    if (iv_len > 0)

        memcpy(k_i, iv, iv_len);

    for (counter = 1; written < ko_len; counter++) {

        i = be32(counter);

        ctx = EVP_MAC_CTX_dup(ctx_init);

        if (ctx == NULL)

            goto done;

        /* Perform feedback, if appropriate. */

        if (mode == FEEDBACK && !EVP_MAC_update(ctx, k_i, k_i_len))

            goto done;

        if (!EVP_MAC_update(ctx, (unsigned char *)&i, 4)

            || !EVP_MAC_update(ctx, label, label_len)

            || (has_separator && !EVP_MAC_update(ctx, &zero, 1))

            || !EVP_MAC_update(ctx, context, context_len)

            || (has_l && !EVP_MAC_update(ctx, (unsigned char *)&l, 4))

            || !EVP_MAC_final(ctx, k_i, NULL, h))

            goto done;

        to_write = ko_len - written;

        memcpy(ko + written, k_i, ossl_min(to_write, h));

        written += h;

        k_i_len = h;

        EVP_MAC_CTX_free(ctx);

        ctx = NULL;

    }

    ret = 1;

done:

    EVP_MAC_CTX_free(ctx);

    return ret;

}

static int kbkdf_derive(void *vctx, unsigned char *key, size_t keylen,

                        const OSSL_PARAM params[])

{

    KBKDF *ctx = (KBKDF *)vctx;

    int ret = 0;

    unsigned char *k_i = NULL;

    uint32_t l = 0;

    size_t h = 0;

    if (!ossl_prov_is_running() || !kbkdf_set_ctx_params(ctx, params))

        return 0;

    /* label, context, and iv are permitted to be empty.  Check everything

     * else. */

    if (ctx->ctx_init == NULL) {

        if (ctx->ki_len == 0 || ctx->ki == NULL) {

            ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);

            return 0;

        }

        /* Could either be missing MAC or missing message digest or missing

         * cipher - arbitrarily, I pick this one. */

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MAC);

        return 0;

    }

    /* Fail if the output length is zero */

    if (keylen == 0) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);

        return 0;

    }

    h = EVP_MAC_CTX_get_mac_size(ctx->ctx_init);

    if (h == 0)

        goto done;

    if (ctx->iv_len != 0 && ctx->iv_len != h) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SEED_LENGTH);

        goto done;

    }

    if (ctx->use_l != 0)

        l = be32(keylen * 8);

    k_i = OPENSSL_zalloc(h);

    if (k_i == NULL)

        goto done;

    ret = derive(ctx->ctx_init, ctx->mode, ctx->iv, ctx->iv_len, ctx->label,

                 ctx->label_len, ctx->context, ctx->context_len, k_i, h, l,

                 ctx->use_separator, key, keylen);

done:

    if (ret != 1)

        OPENSSL_cleanse(key, keylen);

    OPENSSL_clear_free(k_i, h);

    return ret;

}

static int kbkdf_set_buffer(unsigned char **out, size_t *out_len,

                            const OSSL_PARAM *p)

{

    if (p->data == NULL || p->data_size == 0)

        return 1;

    OPENSSL_clear_free(*out, *out_len);

    *out = NULL;

    return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);

}

static int kbkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])

{

    KBKDF *ctx = (KBKDF *)vctx;

    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);

    const OSSL_PARAM *p;

    if (params == NULL)

        return 1;

    if (!ossl_prov_macctx_load_from_params(&ctx->ctx_init, params, NULL,

                                           NULL, NULL, libctx))

        return 0;

    else if (ctx->ctx_init != NULL

             && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),

                              OSSL_MAC_NAME_HMAC)

             && !EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->ctx_init),

                              OSSL_MAC_NAME_CMAC)) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MAC);

        return 0;

    }

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE);

    if (p != NULL

        && OPENSSL_strncasecmp("counter", p->data, p->data_size) == 0) {

        ctx->mode = COUNTER;

    } else if (p != NULL

               && OPENSSL_strncasecmp("feedback", p->data, p->data_size) == 0) {

        ctx->mode = FEEDBACK;

    } else if (p != NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);

        return 0;

    }

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY);

    if (p != NULL && !kbkdf_set_buffer(&ctx->ki, &ctx->ki_len, p))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT);

    if (p != NULL && !kbkdf_set_buffer(&ctx->label, &ctx->label_len, p))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO);

    if (p != NULL && !kbkdf_set_buffer(&ctx->context, &ctx->context_len, p))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED);

    if (p != NULL && !kbkdf_set_buffer(&ctx->iv, &ctx->iv_len, p))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_L);

    if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_l))

        return 0;

    p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR);

    if (p != NULL && !OSSL_PARAM_get_int(p, &ctx->use_separator))

        return 0;

    /* Set up digest context, if we can. */

    if (ctx->ctx_init != NULL && ctx->ki_len != 0

            && !EVP_MAC_init(ctx->ctx_init, ctx->ki, ctx->ki_len, NULL))

            return 0;

    return 1;

}

static const OSSL_PARAM *kbkdf_settable_ctx_params(ossl_unused void *ctx,

                                                   ossl_unused void *provctx)

{

    static const OSSL_PARAM known_settable_ctx_params[] = {

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_CIPHER, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),

        OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_L, NULL),

        OSSL_PARAM_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, NULL),

        OSSL_PARAM_END,

    };

    return known_settable_ctx_params;

}

static int kbkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])

{

    OSSL_PARAM *p;

    p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE);

    if (p == NULL)

        return -2;

    /* KBKDF can produce results as large as you like. */

    return OSSL_PARAM_set_size_t(p, SIZE_MAX);

}

static const OSSL_PARAM *kbkdf_gettable_ctx_params(ossl_unused void *ctx,

                                                   ossl_unused void *provctx)

{

    static const OSSL_PARAM known_gettable_ctx_params[] =

        { OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL), OSSL_PARAM_END };

    return known_gettable_ctx_params;

}

const OSSL_DISPATCH ossl_kdf_kbkdf_functions[] = {

    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kbkdf_new },

    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kbkdf_free },

    { OSSL_FUNC_KDF_RESET, (void(*)(void))kbkdf_reset },

    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kbkdf_derive },

    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,

      (void(*)(void))kbkdf_settable_ctx_params },

    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kbkdf_set_ctx_params },

    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,

      (void(*)(void))kbkdf_gettable_ctx_params },

    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kbkdf_get_ctx_params },

    { 0, NULL },

};