cipher.c

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/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <[email protected]>
 * Copyright (c) 2005 Herbert Xu <[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 <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)
{
}