1 /* 2 * QEMU Crypto block device encryption QCow/QCow2 AES-CBC 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 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 /* 22 * Note that the block encryption implemented in this file is broken 23 * by design. This exists only to allow data to be liberated from 24 * existing qcow[2] images and should not be used in any new areas. 25 */ 26 27 #include "qemu/osdep.h" 28 #include "qapi/error.h" 29 30 #include "crypto/block-qcow.h" 31 #include "crypto/secret.h" 32 33 #define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512 34 35 36 static bool 37 qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED, 38 size_t buf_size G_GNUC_UNUSED) 39 { 40 return false; 41 } 42 43 44 static int 45 qcrypto_block_qcow_init(QCryptoBlock *block, 46 const char *keysecret, 47 Error **errp) 48 { 49 char *password; 50 int ret; 51 uint8_t keybuf[16]; 52 int len; 53 54 memset(keybuf, 0, 16); 55 56 password = qcrypto_secret_lookup_as_utf8(keysecret, errp); 57 if (!password) { 58 return -1; 59 } 60 61 len = strlen(password); 62 memcpy(keybuf, password, MIN(len, sizeof(keybuf))); 63 g_free(password); 64 65 block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128, 66 QCRYPTO_CIPHER_MODE_CBC); 67 block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64, 68 0, 0, NULL, 0, errp); 69 if (!block->ivgen) { 70 ret = -ENOTSUP; 71 goto fail; 72 } 73 74 block->cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128, 75 QCRYPTO_CIPHER_MODE_CBC, 76 keybuf, G_N_ELEMENTS(keybuf), 77 errp); 78 if (!block->cipher) { 79 ret = -ENOTSUP; 80 goto fail; 81 } 82 83 block->payload_offset = 0; 84 85 return 0; 86 87 fail: 88 qcrypto_cipher_free(block->cipher); 89 qcrypto_ivgen_free(block->ivgen); 90 return ret; 91 } 92 93 94 static int 95 qcrypto_block_qcow_open(QCryptoBlock *block, 96 QCryptoBlockOpenOptions *options, 97 QCryptoBlockReadFunc readfunc G_GNUC_UNUSED, 98 void *opaque G_GNUC_UNUSED, 99 unsigned int flags, 100 Error **errp) 101 { 102 if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) { 103 return 0; 104 } else { 105 if (!options->u.qcow.key_secret) { 106 error_setg(errp, 107 "Parameter 'key-secret' is required for cipher"); 108 return -1; 109 } 110 return qcrypto_block_qcow_init(block, 111 options->u.qcow.key_secret, errp); 112 } 113 } 114 115 116 static int 117 qcrypto_block_qcow_create(QCryptoBlock *block, 118 QCryptoBlockCreateOptions *options, 119 QCryptoBlockInitFunc initfunc G_GNUC_UNUSED, 120 QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED, 121 void *opaque G_GNUC_UNUSED, 122 Error **errp) 123 { 124 if (!options->u.qcow.key_secret) { 125 error_setg(errp, "Parameter 'key-secret' is required for cipher"); 126 return -1; 127 } 128 /* QCow2 has no special header, since everything is hardwired */ 129 return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp); 130 } 131 132 133 static void 134 qcrypto_block_qcow_cleanup(QCryptoBlock *block) 135 { 136 } 137 138 139 static int 140 qcrypto_block_qcow_decrypt(QCryptoBlock *block, 141 uint64_t startsector, 142 uint8_t *buf, 143 size_t len, 144 Error **errp) 145 { 146 return qcrypto_block_decrypt_helper(block->cipher, 147 block->niv, block->ivgen, 148 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE, 149 startsector, buf, len, errp); 150 } 151 152 153 static int 154 qcrypto_block_qcow_encrypt(QCryptoBlock *block, 155 uint64_t startsector, 156 uint8_t *buf, 157 size_t len, 158 Error **errp) 159 { 160 return qcrypto_block_encrypt_helper(block->cipher, 161 block->niv, block->ivgen, 162 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE, 163 startsector, buf, len, errp); 164 } 165 166 167 const QCryptoBlockDriver qcrypto_block_driver_qcow = { 168 .open = qcrypto_block_qcow_open, 169 .create = qcrypto_block_qcow_create, 170 .cleanup = qcrypto_block_qcow_cleanup, 171 .decrypt = qcrypto_block_qcow_decrypt, 172 .encrypt = qcrypto_block_qcow_encrypt, 173 .has_format = qcrypto_block_qcow_has_format, 174 }; 175