crypto/cipher.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Cipher operations.
   5  *
   6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   7  * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the Free
  11  * Software Foundation; either version 2 of the License, or (at your option)
  12  * any later version.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/crypto.h>
  18 #include <linux/errno.h>
  19 #include <linux/slab.h>
  20 #include <linux/string.h>
  21 #include "internal.h"
  22
  23 static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
  24                             unsigned int keylen)
  25 {
  26         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
  27         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  28         int ret;
  29         u8 *buffer, *alignbuffer;
  30         unsigned long absize;
  31
  32         absize = keylen + alignmask;
  33         buffer = kmalloc(absize, GFP_ATOMIC);
  34         if (!buffer)
  35                 return -ENOMEM;
  36
  37         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
  38         memcpy(alignbuffer, key, keylen);
  39         ret = cia->cia_setkey(tfm, alignbuffer, keylen);
  40         memset(alignbuffer, 0, keylen);
  41         kfree(buffer);
  42         return ret;
  43
  44 }
  45
  46 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
  47 {
  48         struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
  49         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  50
  51         tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
  52         if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
  53                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  54                 return -EINVAL;
  55         }
  56
  57         if ((unsigned long)key & alignmask)
  58                 return setkey_unaligned(tfm, key, keylen);
  59
  60         return cia->cia_setkey(tfm, key, keylen);
  61 }
  62
  63 static void cipher_crypt_unaligned(void (*fn)(struct crypto_tfm *, u8 *,
  64                                               const u8 *),
  65                                    struct crypto_tfm *tfm,
  66                                    u8 *dst, const u8 *src)
  67 {
  68         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  69         unsigned int size = crypto_tfm_alg_blocksize(tfm);
  70         u8 buffer[size + alignmask];
  71         u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
  72
  73         memcpy(tmp, src, size);
  74         fn(tfm, tmp, tmp);
  75         memcpy(dst, tmp, size);
  76 }
  77
  78 static void cipher_encrypt_unaligned(struct crypto_tfm *tfm,
  79                                      u8 *dst, const u8 *src)
  80 {
  81         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  82         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
  83
  84         if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
  85                 cipher_crypt_unaligned(cipher->cia_encrypt, tfm, dst, src);
  86                 return;
  87         }
  88
  89         cipher->cia_encrypt(tfm, dst, src);
  90 }
  91
  92 static void cipher_decrypt_unaligned(struct crypto_tfm *tfm,
  93                                      u8 *dst, const u8 *src)
  94 {
  95         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  96         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
  97
  98         if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
  99                 cipher_crypt_unaligned(cipher->cia_decrypt, tfm, dst, src);
 100                 return;
 101         }
 102
 103         cipher->cia_decrypt(tfm, dst, src);
 104 }
 105
 106 int crypto_init_cipher_ops(struct crypto_tfm *tfm)
 107 {
 108         struct cipher_tfm *ops = &tfm->crt_cipher;
 109         struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
 110
 111         ops->cit_setkey = setkey;
 112         ops->cit_encrypt_one = crypto_tfm_alg_alignmask(tfm) ?
 113                 cipher_encrypt_unaligned : cipher->cia_encrypt;
 114         ops->cit_decrypt_one = crypto_tfm_alg_alignmask(tfm) ?
 115                 cipher_decrypt_unaligned : cipher->cia_decrypt;
 116
 117         return 0;
 118 }