linux-imx

/*

 * ECDH helper functions - KPP wrappings

 *

 * Copyright (C) 2017 Intel Corporation

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.

 * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY

 * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 *

 * ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,

 * COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS

 * SOFTWARE IS DISCLAIMED.

 */

#include "ecdh_helper.h"

​

#include <linux/scatterlist.h>

#include <crypto/ecdh.h>

​

struct ecdh_completion {

    struct completion completion;

    int err;

};

​

static void ecdh_complete(struct crypto_async_request *req, int err)

{

    struct ecdh_completion *res = req->data;

​

    if (err == -EINPROGRESS)

        return;

​

    res->err = err;

    complete(&res->completion);

}

​

static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits)

{

    int i;

​

    for (i = 0; i < ndigits; i++)

        out[i] = __swab64(in[ndigits - 1 - i]);

}

​

/* compute_ecdh_secret() - function assumes that the private key was

 *                         already set.

 * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().

 * @public_key:   pair's ecc public key.

 * secret:        memory where the ecdh computed shared secret will be saved.

 *

 * Return: zero on success; error code in case of error.

 */

int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64],

            u8 secret[32])

{

    struct kpp_request *req;

    u8 *tmp;

    struct ecdh_completion result;

    struct scatterlist src, dst;

    int err;

​

    tmp = kmalloc(64, GFP_KERNEL);

    if (!tmp)

        return -ENOMEM;

​

    req = kpp_request_alloc(tfm, GFP_KERNEL);

    if (!req) {

        err = -ENOMEM;

        goto free_tmp;

    }

​

    init_completion(&result.completion);

​

    swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */

    swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */

​

    sg_init_one(&src, tmp, 64);

    sg_init_one(&dst, secret, 32);

    kpp_request_set_input(req, &src, 64);

    kpp_request_set_output(req, &dst, 32);

    kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,

                 ecdh_complete, &result);

    err = crypto_kpp_compute_shared_secret(req);

    if (err == -EINPROGRESS) {

        wait_for_completion(&result.completion);