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 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 *)§or, 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 }; 120 121