fpu.c

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/*
 * FPU: Wrapper for blkcipher touching fpu
 *
 * Copyright (c) Intel Corp.
 *   Author: Huang Ying <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <crypto/algapi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/i387.h>

struct crypto_fpu_ctx {
    struct crypto_blkcipher *child;
};

static int crypto_fpu_setkey(struct crypto_tfm *parent, const u8 *key,
                 unsigned int keylen)
{
    struct crypto_fpu_ctx *ctx = crypto_tfm_ctx(parent);
    struct crypto_blkcipher *child = ctx->child;
    int err;

    crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
    crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
                   CRYPTO_TFM_REQ_MASK);
    err = crypto_blkcipher_setkey(child, key, keylen);
    crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
                     CRYPTO_TFM_RES_MASK);
    return err;
}

static int crypto_fpu_encrypt(struct blkcipher_desc *desc_in,
                  struct scatterlist *dst, struct scatterlist *src,
                  unsigned int nbytes)
{
    int err;
    struct crypto_fpu_ctx *ctx = crypto_blkcipher_ctx(desc_in->tfm);
    struct crypto_blkcipher *child = ctx->child;
    struct blkcipher_desc desc = {
        .tfm = child,
        .info = desc_in->info,
        .flags = desc_in->flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
    };

    kernel_fpu_begin();
    err = crypto_blkcipher_crt(desc.tfm)->encrypt(&desc, dst, src, nbytes);
    kernel_fpu_end();
    return err;
}

static int crypto_fpu_decrypt(struct blkcipher_desc *desc_in,
                  struct scatterlist *dst, struct scatterlist *src,
                  unsigned int nbytes)
{
    int err;
    struct crypto_fpu_ctx *ctx = crypto_blkcipher_ctx(desc_in->tfm);
    struct crypto_blkcipher *child = ctx->child;
    struct blkcipher_desc desc = {
        .tfm = child,
        .info = desc_in->info,
        .flags = desc_in->flags & ~CRYPTO_TFM_REQ_MAY_SLEEP,
    };

    kernel_fpu_begin();
    err = crypto_blkcipher_crt(desc.tfm)->decrypt(&desc, dst, src, nbytes);
    kernel_fpu_end();
    return err;
}

static int crypto_fpu_init_tfm(struct crypto_tfm *tfm)
{
    struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
    struct crypto_spawn *spawn = crypto_instance_ctx(inst);
    struct crypto_fpu_ctx *ctx = crypto_tfm_ctx(tfm);
    struct crypto_blkcipher *cipher;

    cipher = crypto_spawn_blkcipher(spawn);
    if (IS_ERR(cipher))
        return PTR_ERR(cipher);

    ctx->child = cipher;
    return 0;
}

static void crypto_fpu_exit_tfm(struct crypto_tfm *tfm)
{
    struct crypto_fpu_ctx *ctx = crypto_tfm_ctx(tfm);
    crypto_free_blkcipher(ctx->child);
}

static struct crypto_instance *crypto_fpu_alloc(struct rtattr **tb)
{
    struct crypto_instance *inst;
    struct crypto_alg *alg;
    int err;

    err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
    if (err)
        return ERR_PTR(err);

    alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_BLKCIPHER,
                  CRYPTO_ALG_TYPE_MASK);
    if (IS_ERR(alg))
        return ERR_CAST(alg);

    inst = crypto_alloc_instance("fpu", alg);
    if (IS_ERR(inst))
        goto out_put_alg;

    inst->alg.cra_flags = alg->cra_flags;
    inst->alg.cra_priority = alg->cra_priority;
    inst->alg.cra_blocksize = alg->cra_blocksize;
    inst->alg.cra_alignmask = alg->cra_alignmask;
    inst->alg.cra_type = alg->cra_type;
    inst->alg.cra_blkcipher.ivsize = alg->cra_blkcipher.ivsize;
    inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
    inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize;
    inst->alg.cra_ctxsize = sizeof(struct crypto_fpu_ctx);
    inst->alg.cra_init = crypto_fpu_init_tfm;
    inst->alg.cra_exit = crypto_fpu_exit_tfm;
    inst->alg.cra_blkcipher.setkey = crypto_fpu_setkey;
    inst->alg.cra_blkcipher.encrypt = crypto_fpu_encrypt;
    inst->alg.cra_blkcipher.decrypt = crypto_fpu_decrypt;

out_put_alg:
    crypto_mod_put(alg);
    return inst;
}

static void crypto_fpu_free(struct crypto_instance *inst)
{
    crypto_drop_spawn(crypto_instance_ctx(inst));
    kfree(inst);
}

static struct crypto_template crypto_fpu_tmpl = {
    .name = "fpu",
    .alloc = crypto_fpu_alloc,
    .free = crypto_fpu_free,
    .module = THIS_MODULE,
};

int __init crypto_fpu_init(void)
{
    return crypto_register_template(&crypto_fpu_tmpl);
}

void __exit crypto_fpu_exit(void)
{
    crypto_unregister_template(&crypto_fpu_tmpl);
}