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 "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 size_t n_threads, 48 Error **errp) 49 { 50 char *password; 51 int ret; 52 uint8_t keybuf[16]; 53 int len; 54 55 memset(keybuf, 0, 16); 56 57 password = qcrypto_secret_lookup_as_utf8(keysecret, errp); 58 if (!password) { 59 return -1; 60 } 61 62 len = strlen(password); 63 memcpy(keybuf, password, MIN(len, sizeof(keybuf))); 64 g_free(password); 65 66 block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128, 67 QCRYPTO_CIPHER_MODE_CBC); 68 block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64, 69 0, 0, NULL, 0, errp); 70 if (!block->ivgen) { 71 ret = -ENOTSUP; 72 goto fail; 73 } 74 75 ret = qcrypto_block_init_cipher(block, QCRYPTO_CIPHER_ALG_AES_128, 76 QCRYPTO_CIPHER_MODE_CBC, 77 keybuf, G_N_ELEMENTS(keybuf), 78 n_threads, errp); 79 if (ret < 0) { 80 ret = -ENOTSUP; 81 goto fail; 82 } 83 84 block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE; 85 block->payload_offset = 0; 86 87 return 0; 88 89 fail: 90 qcrypto_block_free_cipher(block); 91 qcrypto_ivgen_free(block->ivgen); 92 return ret; 93 } 94 95 96 static int 97 qcrypto_block_qcow_open(QCryptoBlock *block, 98 QCryptoBlockOpenOptions *options, 99 const char *optprefix, 100 QCryptoBlockReadFunc readfunc G_GNUC_UNUSED, 101 void *opaque G_GNUC_UNUSED, 102 unsigned int flags, 103 size_t n_threads, 104 Error **errp) 105 { 106 if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) { 107 block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE; 108 block->payload_offset = 0; 109 return 0; 110 } else { 111 if (!options->u.qcow.key_secret) { 112 error_setg(errp, 113 "Parameter '%skey-secret' is required for cipher", 114 optprefix ? optprefix : ""); 115 return -1; 116 } 117 return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, 118 n_threads, errp); 119 } 120 } 121 122 123 static int 124 qcrypto_block_qcow_create(QCryptoBlock *block, 125 QCryptoBlockCreateOptions *options, 126 const char *optprefix, 127 QCryptoBlockInitFunc initfunc G_GNUC_UNUSED, 128 QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED, 129 void *opaque G_GNUC_UNUSED, 130 Error **errp) 131 { 132 if (!options->u.qcow.key_secret) { 133 error_setg(errp, "Parameter '%skey-secret' is required for cipher", 134 optprefix ? optprefix : ""); 135 return -1; 136 } 137 /* QCow2 has no special header, since everything is hardwired */ 138 return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, 1, errp); 139 } 140 141 142 static void 143 qcrypto_block_qcow_cleanup(QCryptoBlock *block) 144 { 145 } 146 147 148 static int 149 qcrypto_block_qcow_decrypt(QCryptoBlock *block, 150 uint64_t offset, 151 uint8_t *buf, 152 size_t len, 153 Error **errp) 154 { 155 assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE)); 156 assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE)); 157 return qcrypto_block_decrypt_helper(block, 158 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE, 159 offset, buf, len, errp); 160 } 161 162 163 static int 164 qcrypto_block_qcow_encrypt(QCryptoBlock *block, 165 uint64_t offset, 166 uint8_t *buf, 167 size_t len, 168 Error **errp) 169 { 170 assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE)); 171 assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE)); 172 return qcrypto_block_encrypt_helper(block, 173 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE, 174 offset, buf, len, errp); 175 } 176 177 178 const QCryptoBlockDriver qcrypto_block_driver_qcow = { 179 .open = qcrypto_block_qcow_open, 180 .create = qcrypto_block_qcow_create, 181 .cleanup = qcrypto_block_qcow_cleanup, 182 .decrypt = qcrypto_block_qcow_decrypt, 183 .encrypt = qcrypto_block_qcow_encrypt, 184 .has_format = qcrypto_block_qcow_has_format, 185 }; 186