linux-imx

// SPDX-License-Identifier: GPL-2.0

​

/*

 * OFB: Output FeedBack mode

 *

 * Copyright (C) 2018 ARM Limited or its affiliates.

 * All rights reserved.

 */

​

#include <crypto/algapi.h>

#include <crypto/internal/skcipher.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

​

static int crypto_ofb_crypt(struct skcipher_request *req)

{

    struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);

    struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);

    const unsigned int bsize = crypto_cipher_blocksize(cipher);

    struct skcipher_walk walk;

    int err;

​

    err = skcipher_walk_virt(&walk, req, false);

​

    while (walk.nbytes >= bsize) {

        const u8 *src = walk.src.virt.addr;

        u8 *dst = walk.dst.virt.addr;

        u8 * const iv = walk.iv;

        unsigned int nbytes = walk.nbytes;

​

        do {

            crypto_cipher_encrypt_one(cipher, iv, iv);

            crypto_xor_cpy(dst, src, iv, bsize);

            dst += bsize;

            src += bsize;

        } while ((nbytes -= bsize) >= bsize);

​

        err = skcipher_walk_done(&walk, nbytes);

    }

​

    if (walk.nbytes) {

        crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);

        crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,

                   walk.nbytes);

        err = skcipher_walk_done(&walk, 0);

    }

    return err;

}

​

static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)

{

    struct skcipher_instance *inst;

    struct crypto_alg *alg;

    int err;

​

    inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);

    if (IS_ERR(inst))

        return PTR_ERR(inst);

​

    /* OFB mode is a stream cipher. */

    inst->alg.base.cra_blocksize = 1;