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1 /*
2 * QEMU Crypto block device encryption LUKS format
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 "qapi/error.h"
22 #include "qemu/bswap.h"
23
24 #include "block-luks.h"
25
26 #include "crypto/hash.h"
27 #include "crypto/afsplit.h"
28 #include "crypto/pbkdf.h"
29 #include "crypto/secret.h"
30 #include "crypto/random.h"
31 #include "qemu/uuid.h"
32
33 #include "qemu/bitmap.h"
34
35 /*
36 * Reference for the LUKS format implemented here is
37 *
38 * docs/on-disk-format.pdf
39 *
40 * in 'cryptsetup' package source code
41 *
42 * This file implements the 1.2.1 specification, dated
43 * Oct 16, 2011.
44 */
45
46 typedef struct QCryptoBlockLUKSHeader QCryptoBlockLUKSHeader;
47 typedef struct QCryptoBlockLUKSKeySlot QCryptoBlockLUKSKeySlot;
48
49
50 /* The following constants are all defined by the LUKS spec */
51 #define QCRYPTO_BLOCK_LUKS_VERSION 1
52
53 #define QCRYPTO_BLOCK_LUKS_MAGIC_LEN 6
54 #define QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN 32
55 #define QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN 32
56 #define QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN 32
57 #define QCRYPTO_BLOCK_LUKS_DIGEST_LEN 20
58 #define QCRYPTO_BLOCK_LUKS_SALT_LEN 32
59 #define QCRYPTO_BLOCK_LUKS_UUID_LEN 40
60 #define QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS 8
61 #define QCRYPTO_BLOCK_LUKS_STRIPES 4000
62 #define QCRYPTO_BLOCK_LUKS_MIN_SLOT_KEY_ITERS 1000
63 #define QCRYPTO_BLOCK_LUKS_MIN_MASTER_KEY_ITERS 1000
64 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_OFFSET 4096
65
66 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_DISABLED 0x0000DEAD
67 #define QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED 0x00AC71F3
68
69 #define QCRYPTO_BLOCK_LUKS_SECTOR_SIZE 512LL
70
71 #define QCRYPTO_BLOCK_LUKS_DEFAULT_ITER_TIME_MS 2000
72 #define QCRYPTO_BLOCK_LUKS_ERASE_ITERATIONS 40
73
74 static const char qcrypto_block_luks_magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN] = {
75 'L', 'U', 'K', 'S', 0xBA, 0xBE
76 };
77
78 /*
79 * This struct is written to disk in big-endian format,
80 * but operated upon in native-endian format.
81 */
82 struct QCryptoBlockLUKSKeySlot {
83 /* state of keyslot, enabled/disable */
84 uint32_t active;
85 /* iterations for PBKDF2 */
86 uint32_t iterations;
87 /* salt for PBKDF2 */
88 uint8_t salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
89 /* start sector of key material */
90 uint32_t key_offset_sector;
91 /* number of anti-forensic stripes */
92 uint32_t stripes;
93 };
94
95 /*
96 * This struct is written to disk in big-endian format,
97 * but operated upon in native-endian format.
98 */
99 struct QCryptoBlockLUKSHeader {
100 /* 'L', 'U', 'K', 'S', '0xBA', '0xBE' */
101 char magic[QCRYPTO_BLOCK_LUKS_MAGIC_LEN];
102
103 /* LUKS version, currently 1 */
104 uint16_t version;
105
106 /* cipher name specification (aes, etc) */
107 char cipher_name[QCRYPTO_BLOCK_LUKS_CIPHER_NAME_LEN];
108
109 /* cipher mode specification (cbc-plain, xts-essiv:sha256, etc) */
110 char cipher_mode[QCRYPTO_BLOCK_LUKS_CIPHER_MODE_LEN];
111
112 /* hash specification (sha256, etc) */
113 char hash_spec[QCRYPTO_BLOCK_LUKS_HASH_SPEC_LEN];
114
115 /* start offset of the volume data (in 512 byte sectors) */
116 uint32_t payload_offset_sector;
117
118 /* Number of key bytes */
119 uint32_t master_key_len;
120
121 /* master key checksum after PBKDF2 */
122 uint8_t master_key_digest[QCRYPTO_BLOCK_LUKS_DIGEST_LEN];
123
124 /* salt for master key PBKDF2 */
125 uint8_t master_key_salt[QCRYPTO_BLOCK_LUKS_SALT_LEN];
126
127 /* iterations for master key PBKDF2 */
128 uint32_t master_key_iterations;
129
130 /* UUID of the partition in standard ASCII representation */
131 uint8_t uuid[QCRYPTO_BLOCK_LUKS_UUID_LEN];
132
133 /* key slots */
134 QCryptoBlockLUKSKeySlot key_slots[QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS];
135 };
136
137
138 void
139 qcrypto_block_luks_to_disk_endian(QCryptoBlockLUKSHeader *hdr);
140 void
141 qcrypto_block_luks_from_disk_endian(QCryptoBlockLUKSHeader *hdr);