xref: /openbmc/qemu/crypto/ivgen-essiv.c (revision cb730894) 
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 "crypto/ivgen-essiv.h"
23 
24 typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
25 struct QCryptoIVGenESSIV {
26     QCryptoCipher *cipher;
27 };
28 
29 static int qcrypto_ivgen_essiv_init(QCryptoIVGen *ivgen,
30                                     const uint8_t *key, size_t nkey,
31                                     Error **errp)
32 {
33     uint8_t *salt;
34     size_t nhash;
35     size_t nsalt;
36     QCryptoIVGenESSIV *essiv = g_new0(QCryptoIVGenESSIV, 1);
37 
38     /* Not necessarily the same as nkey */
39     nsalt = qcrypto_cipher_get_key_len(ivgen->cipher);
40 
41     nhash = qcrypto_hash_digest_len(ivgen->hash);
42     /* Salt must be larger of hash size or key size */
43     salt = g_new0(uint8_t, MAX(nhash, nsalt));
44 
45     if (qcrypto_hash_bytes(ivgen->hash, (const gchar *)key, nkey,
46                            &salt, &nhash,
47                            errp) < 0) {
48         g_free(essiv);
49         return -1;
50     }
51 
52     /* Now potentially truncate salt to match cipher key len */
53     essiv->cipher = qcrypto_cipher_new(ivgen->cipher,
54                                        QCRYPTO_CIPHER_MODE_ECB,
55                                        salt, MIN(nhash, nsalt),
56                                        errp);
57     if (!essiv->cipher) {
58         g_free(essiv);
59         g_free(salt);
60         return -1;
61     }
62 
63     g_free(salt);
64     ivgen->private = essiv;
65 
66     return 0;
67 }
68 
69 static int qcrypto_ivgen_essiv_calculate(QCryptoIVGen *ivgen,
70                                          uint64_t sector,
71                                          uint8_t *iv, size_t niv,
72                                          Error **errp)
73 {
74     QCryptoIVGenESSIV *essiv = ivgen->private;
75     size_t ndata = qcrypto_cipher_get_block_len(ivgen->cipher);
76     uint8_t *data = g_new(uint8_t, ndata);
77 
78     sector = cpu_to_le64(sector);
79     memcpy(data, (uint8_t *)&sector, ndata);
80     if (sizeof(sector) < ndata) {
81         memset(data + sizeof(sector), 0, ndata - sizeof(sector));
82     }
83 
84     if (qcrypto_cipher_encrypt(essiv->cipher,
85                                data,
86                                data,
87                                ndata,
88                                errp) < 0) {
89         g_free(data);
90         return -1;
91     }
92 
93     if (ndata > niv) {
94         ndata = niv;
95     }
96     memcpy(iv, data, ndata);
97     if (ndata < niv) {
98         memset(iv + ndata, 0, niv - ndata);
99     }
100     g_free(data);
101     return 0;
102 }
103 
104 static void qcrypto_ivgen_essiv_cleanup(QCryptoIVGen *ivgen)
105 {
106     QCryptoIVGenESSIV *essiv = ivgen->private;
107 
108     qcrypto_cipher_free(essiv->cipher);
109     g_free(essiv);
110 }
111 
112 
113 struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
114     .init = qcrypto_ivgen_essiv_init,
115     .calculate = qcrypto_ivgen_essiv_calculate,
116     .cleanup = qcrypto_ivgen_essiv_cleanup,
117 };
118 
119