crypto/block-qcow.c

   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 2.1 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 /*
  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 };