qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
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ivgen-essiv.c (3571B)

      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 2.1 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 
     25 typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
     26 struct QCryptoIVGenESSIV {
     27     QCryptoCipher *cipher;
     28 };
     29 
     30 static 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 
     71 static 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 
    106 static 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 
    115 struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
    116     .init = qcrypto_ivgen_essiv_init,
    117     .calculate = qcrypto_ivgen_essiv_calculate,
    118     .cleanup = qcrypto_ivgen_essiv_cleanup,
    119 };
    120