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ecb.c

/*
 * ECB: Electronic CodeBook mode
 *
 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * 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/scatterlist.h>
#include <linux/slab.h>

struct crypto_ecb_ctx {
      struct crypto_cipher *child;
};

static int crypto_ecb_setkey(struct crypto_tfm *parent, const u8 *key,
                       unsigned int keylen)
{
      struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(parent);
      struct crypto_cipher *child = ctx->child;
      int err;

      crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
      crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
                               CRYPTO_TFM_REQ_MASK);
      err = crypto_cipher_setkey(child, key, keylen);
      crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
                             CRYPTO_TFM_RES_MASK);
      return err;
}

static int crypto_ecb_crypt(struct blkcipher_desc *desc,
                      struct blkcipher_walk *walk,
                      struct crypto_cipher *tfm,
                      void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
{
      int bsize = crypto_cipher_blocksize(tfm);
      unsigned int nbytes;
      int err;

      err = blkcipher_walk_virt(desc, walk);

      while ((nbytes = walk->nbytes)) {
            u8 *wsrc = walk->src.virt.addr;
            u8 *wdst = walk->dst.virt.addr;

            do {
                  fn(crypto_cipher_tfm(tfm), wdst, wsrc);
      
                  wsrc += bsize;
                  wdst += bsize;
            } while ((nbytes -= bsize) >= bsize);

            err = blkcipher_walk_done(desc, walk, nbytes);
      }

      return err;
}

static int crypto_ecb_encrypt(struct blkcipher_desc *desc,
                        struct scatterlist *dst, struct scatterlist *src,
                        unsigned int nbytes)
{
      struct blkcipher_walk walk;
      struct crypto_blkcipher *tfm = desc->tfm;
      struct crypto_ecb_ctx *ctx = crypto_blkcipher_ctx(tfm);
      struct crypto_cipher *child = ctx->child;

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return crypto_ecb_crypt(desc, &walk, child,
                        crypto_cipher_alg(child)->cia_encrypt);
}

static int crypto_ecb_decrypt(struct blkcipher_desc *desc,
                        struct scatterlist *dst, struct scatterlist *src,
                        unsigned int nbytes)
{
      struct blkcipher_walk walk;
      struct crypto_blkcipher *tfm = desc->tfm;
      struct crypto_ecb_ctx *ctx = crypto_blkcipher_ctx(tfm);
      struct crypto_cipher *child = ctx->child;

      blkcipher_walk_init(&walk, dst, src, nbytes);
      return crypto_ecb_crypt(desc, &walk, child,
                        crypto_cipher_alg(child)->cia_decrypt);
}

static int crypto_ecb_init_tfm(struct crypto_tfm *tfm)
{
      struct crypto_instance *inst = (void *)tfm->__crt_alg;
      struct crypto_spawn *spawn = crypto_instance_ctx(inst);
      struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(tfm);
      struct crypto_cipher *cipher;

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

      ctx->child = cipher;
      return 0;
}

static void crypto_ecb_exit_tfm(struct crypto_tfm *tfm)
{
      struct crypto_ecb_ctx *ctx = crypto_tfm_ctx(tfm);
      crypto_free_cipher(ctx->child);
}

static struct crypto_instance *crypto_ecb_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_CIPHER,
                          CRYPTO_ALG_TYPE_MASK);
      if (IS_ERR(alg))
            return ERR_PTR(PTR_ERR(alg));

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

      inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
      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 = &crypto_blkcipher_type;

      inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
      inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;

      inst->alg.cra_ctxsize = sizeof(struct crypto_ecb_ctx);

      inst->alg.cra_init = crypto_ecb_init_tfm;
      inst->alg.cra_exit = crypto_ecb_exit_tfm;

      inst->alg.cra_blkcipher.setkey = crypto_ecb_setkey;
      inst->alg.cra_blkcipher.encrypt = crypto_ecb_encrypt;
      inst->alg.cra_blkcipher.decrypt = crypto_ecb_decrypt;

out_put_alg:
      crypto_mod_put(alg);
      return inst;
}

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

static struct crypto_template crypto_ecb_tmpl = {
      .name = "ecb",
      .alloc = crypto_ecb_alloc,
      .free = crypto_ecb_free,
      .module = THIS_MODULE,
};

static int __init crypto_ecb_module_init(void)
{
      return crypto_register_template(&crypto_ecb_tmpl);
}

static void __exit crypto_ecb_module_exit(void)
{
      crypto_unregister_template(&crypto_ecb_tmpl);
}

module_init(crypto_ecb_module_init);
module_exit(crypto_ecb_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ECB block cipher algorithm");

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