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cipher.c

/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2005 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 <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include "internal.h"

static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
                      unsigned int keylen)
{
      struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
      int ret;
      u8 *buffer, *alignbuffer;
      unsigned long absize;

      absize = keylen + alignmask;
      buffer = kmalloc(absize, GFP_ATOMIC);
      if (!buffer)
            return -ENOMEM;

      alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
      memcpy(alignbuffer, key, keylen);
      ret = cia->cia_setkey(tfm, alignbuffer, keylen);
      memset(alignbuffer, 0, keylen);
      kfree(buffer);
      return ret;

}

static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
{
      struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);

      tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
      if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
            tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
            return -EINVAL;
      }

      if ((unsigned long)key & alignmask)
            return setkey_unaligned(tfm, key, keylen);

      return cia->cia_setkey(tfm, key, keylen);
}

static void cipher_crypt_unaligned(void (*fn)(struct crypto_tfm *, u8 *,
                                    const u8 *),
                           struct crypto_tfm *tfm,
                           u8 *dst, const u8 *src)
{
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
      unsigned int size = crypto_tfm_alg_blocksize(tfm);
      u8 buffer[size + alignmask];
      u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);

      memcpy(tmp, src, size);
      fn(tfm, tmp, tmp);
      memcpy(dst, tmp, size);
}

static void cipher_encrypt_unaligned(struct crypto_tfm *tfm,
                             u8 *dst, const u8 *src)
{
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
      struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

      if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
            cipher_crypt_unaligned(cipher->cia_encrypt, tfm, dst, src);
            return;
      }

      cipher->cia_encrypt(tfm, dst, src);
}

static void cipher_decrypt_unaligned(struct crypto_tfm *tfm,
                             u8 *dst, const u8 *src)
{
      unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
      struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

      if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
            cipher_crypt_unaligned(cipher->cia_decrypt, tfm, dst, src);
            return;
      }

      cipher->cia_decrypt(tfm, dst, src);
}

int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
      struct cipher_tfm *ops = &tfm->crt_cipher;
      struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

      ops->cit_setkey = setkey;
      ops->cit_encrypt_one = crypto_tfm_alg_alignmask(tfm) ?
            cipher_encrypt_unaligned : cipher->cia_encrypt;
      ops->cit_decrypt_one = crypto_tfm_alg_alignmask(tfm) ?
            cipher_decrypt_unaligned : cipher->cia_decrypt;

      return 0;
}

void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
{
}

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