xref: /qemu/crypto/ivgen-essiv.c (revision abff1abf) 
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 
121