cipher.c 3.31 KB
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/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
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 *
 * 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
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 * Software Foundation; either version 2 of the License, or (at your option)
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 * any later version.
 *
 */
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#include <crypto/algapi.h>
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#include <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/string.h>
#include "internal.h"

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static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
			    unsigned int keylen)
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{
	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);
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	memset(alignbuffer, 0, keylen);
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	kfree(buffer);
	return ret;

}

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

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

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

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

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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);
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	u8 buffer[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
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	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);
}

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int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
	struct cipher_tfm *ops = &tfm->crt_cipher;
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	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
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	ops->cit_setkey = setkey;
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	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;
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	return 0;
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}