LXR qemu/crypto/ivgen-essiv.c

   1/*
   2 * QEMU Crypto block IV generator - essiv
   3 *
   4 * Copyright (c) 2015-2016 Red Hat, Inc.
   5 *
   6 * This library is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU Lesser General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This library is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * Lesser General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU Lesser General Public
  17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18 *
  19 */
  20
  21#include "qemu/osdep.h"
  22#include "qemu/bswap.h"
  23#include "ivgen-essiv.h"
  24
  25typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
  26struct QCryptoIVGenESSIV {
  27    QCryptoCipher *cipher;
  28};
  29
  30static int qcrypto_ivgen_essiv_init(QCryptoIVGen *ivgen,
  31                                    const uint8_t *key, size_t nkey,
  32                                    Error **errp)
  33{
  34    uint8_t *salt;
  35    size_t nhash;
  36    size_t nsalt;
  37    QCryptoIVGenESSIV *essiv = g_new0(QCryptoIVGenESSIV, 1);
  38
  39    /* Not necessarily the same as nkey */
  40    nsalt = qcrypto_cipher_get_key_len(ivgen->cipher);
  41
  42    nhash = qcrypto_hash_digest_len(ivgen->hash);
  43    /* Salt must be larger of hash size or key size */
  44    salt = g_new0(uint8_t, MAX(nhash, nsalt));
  45
  46    if (qcrypto_hash_bytes(ivgen->hash, (const gchar *)key, nkey,
  47                           &salt, &nhash,
  48                           errp) < 0) {
  49        g_free(essiv);
  50        g_free(salt);
  51        return -1;
  52    }
  53
  54    /* Now potentially truncate salt to match cipher key len */
  55    essiv->cipher = qcrypto_cipher_new(ivgen->cipher,
  56                                       QCRYPTO_CIPHER_MODE_ECB,
  57                                       salt, MIN(nhash, nsalt),
  58                                       errp);
  59    if (!essiv->cipher) {
  60        g_free(essiv);
  61        g_free(salt);
  62        return -1;
  63    }
  64
  65    g_free(salt);
  66    ivgen->private = essiv;
  67
  68    return 0;
  69}
  70
  71static int qcrypto_ivgen_essiv_calculate(QCryptoIVGen *ivgen,
  72                                         uint64_t sector,
  73                                         uint8_t *iv, size_t niv,
  74                                         Error **errp)
  75{
  76    QCryptoIVGenESSIV *essiv = ivgen->private;
  77    size_t ndata = qcrypto_cipher_get_block_len(ivgen->cipher);
  78    uint8_t *data = g_new(uint8_t, ndata);
  79
  80    sector = cpu_to_le64(sector);
  81    memcpy(data, (uint8_t *)&sector, MIN(sizeof(sector), ndata));
  82    if (sizeof(sector) < ndata) {
  83        memset(data + sizeof(sector), 0, ndata - sizeof(sector));
  84    }
  85
  86    if (qcrypto_cipher_encrypt(essiv->cipher,
  87                               data,
  88                               data,
  89                               ndata,
  90                               errp) < 0) {
  91        g_free(data);
  92        return -1;
  93    }
  94
  95    if (ndata > niv) {
  96        ndata = niv;
  97    }
  98    memcpy(iv, data, ndata);
  99    if (ndata < niv) {
 100        memset(iv + ndata, 0, niv - ndata);
 101    }
 102    g_free(data);
 103    return 0;
 104}
 105
 106static void qcrypto_ivgen_essiv_cleanup(QCryptoIVGen *ivgen)
 107{
 108    QCryptoIVGenESSIV *essiv = ivgen->private;
 109
 110    qcrypto_cipher_free(essiv->cipher);
 111    g_free(essiv);
 112}
 113
 114
 115struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
 116    .init = qcrypto_ivgen_essiv_init,
 117    .calculate = qcrypto_ivgen_essiv_calculate,
 118    .cleanup = qcrypto_ivgen_essiv_cleanup,
 119};
 120
 121