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 "qapi/error.h"
  23#include "qemu/bswap.h"
  24#include "crypto/ivgen-essiv.h"
  25
  26typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
  27struct QCryptoIVGenESSIV {
  28    QCryptoCipher *cipher;
  29};
  30
  31static int qcrypto_ivgen_essiv_init(QCryptoIVGen *ivgen,
  32                                    const uint8_t *key, size_t nkey,
  33                                    Error **errp)
  34{
  35    uint8_t *salt;
  36    size_t nhash;
  37    size_t nsalt;
  38    QCryptoIVGenESSIV *essiv = g_new0(QCryptoIVGenESSIV, 1);
  39
  40    /* Not necessarily the same as nkey */
  41    nsalt = qcrypto_cipher_get_key_len(ivgen->cipher);
  42
  43    nhash = qcrypto_hash_digest_len(ivgen->hash);
  44    /* Salt must be larger of hash size or key size */
  45    salt = g_new0(uint8_t, MAX(nhash, nsalt));
  46
  47    if (qcrypto_hash_bytes(ivgen->hash, (const gchar *)key, nkey,
  48                           &salt, &nhash,
  49                           errp) < 0) {
  50        g_free(essiv);
  51        g_free(salt);
  52        return -1;
  53    }
  54
  55    /* Now potentially truncate salt to match cipher key len */
  56    essiv->cipher = qcrypto_cipher_new(ivgen->cipher,
  57                                       QCRYPTO_CIPHER_MODE_ECB,
  58                                       salt, MIN(nhash, nsalt),
  59                                       errp);
  60    if (!essiv->cipher) {
  61        g_free(essiv);
  62        g_free(salt);
  63        return -1;
  64    }
  65
  66    g_free(salt);
  67    ivgen->private = essiv;
  68
  69    return 0;
  70}
  71
  72static int qcrypto_ivgen_essiv_calculate(QCryptoIVGen *ivgen,
  73                                         uint64_t sector,
  74                                         uint8_t *iv, size_t niv,
  75                                         Error **errp)
  76{
  77    QCryptoIVGenESSIV *essiv = ivgen->private;
  78    size_t ndata = qcrypto_cipher_get_block_len(ivgen->cipher);
  79    uint8_t *data = g_new(uint8_t, ndata);
  80
  81    sector = cpu_to_le64(sector);
  82    memcpy(data, (uint8_t *)&sector, ndata);
  83    if (sizeof(sector) < ndata) {
  84        memset(data + sizeof(sector), 0, ndata - sizeof(sector));
  85    }
  86
  87    if (qcrypto_cipher_encrypt(essiv->cipher,
  88                               data,
  89                               data,
  90                               ndata,
  91                               errp) < 0) {
  92        g_free(data);
  93        return -1;
  94    }
  95
  96    if (ndata > niv) {
  97        ndata = niv;
  98    }
  99    memcpy(iv, data, ndata);
 100    if (ndata < niv) {
 101        memset(iv + ndata, 0, niv - ndata);
 102    }
 103    g_free(data);
 104    return 0;
 105}
 106
 107static void qcrypto_ivgen_essiv_cleanup(QCryptoIVGen *ivgen)
 108{
 109    QCryptoIVGenESSIV *essiv = ivgen->private;
 110
 111    qcrypto_cipher_free(essiv->cipher);
 112    g_free(essiv);
 113}
 114
 115
 116struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
 117    .init = qcrypto_ivgen_essiv_init,
 118    .calculate = qcrypto_ivgen_essiv_calculate,
 119    .cleanup = qcrypto_ivgen_essiv_cleanup,
 120};
 121
 122