qemu

block-qcow.c (5855B)

---

 /*
  * QEMU Crypto block device encryption QCow/QCow2 AES-CBC format
  *
  * Copyright (c) 2015-2016 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  *
  */
 
 /*
  * Note that the block encryption implemented in this file is broken
  * by design. This exists only to allow data to be liberated from
  * existing qcow[2] images and should not be used in any new areas.
  */
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 
 #include "block-qcow.h"
 #include "crypto/secret.h"
 
 #define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512
 
 
 static bool
 qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
                               size_t buf_size G_GNUC_UNUSED)
 {
     return false;
 }
 
 
 static int
 qcrypto_block_qcow_init(QCryptoBlock *block,
                         const char *keysecret,
                         size_t n_threads,
                         Error **errp)
 {
     char *password;
     int ret;
     uint8_t keybuf[16];
     int len;
 
     memset(keybuf, 0, 16);
 
     password = qcrypto_secret_lookup_as_utf8(keysecret, errp);
     if (!password) {
         return -1;
     }
 
     len = strlen(password);
     memcpy(keybuf, password, MIN(len, sizeof(keybuf)));
     g_free(password);
 
     block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
                                            QCRYPTO_CIPHER_MODE_CBC);
     block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64,
                                      0, 0, NULL, 0, errp);
     if (!block->ivgen) {
         ret = -ENOTSUP;
         goto fail;
     }
 
     ret = qcrypto_block_init_cipher(block, QCRYPTO_CIPHER_ALG_AES_128,
                                     QCRYPTO_CIPHER_MODE_CBC,
                                     keybuf, G_N_ELEMENTS(keybuf),
                                     n_threads, errp);
     if (ret < 0) {
         ret = -ENOTSUP;
         goto fail;
     }
 
     block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
     block->payload_offset = 0;
 
     return 0;
 
  fail:
     qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
     return ret;
 }
 
 
 static int
 qcrypto_block_qcow_open(QCryptoBlock *block,
                         QCryptoBlockOpenOptions *options,
                         const char *optprefix,
                         QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,
                         void *opaque G_GNUC_UNUSED,
                         unsigned int flags,
                         size_t n_threads,
                         Error **errp)
 {
     if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
         block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
         block->payload_offset = 0;
         return 0;
     } else {
         if (!options->u.qcow.key_secret) {
             error_setg(errp,
                        "Parameter '%skey-secret' is required for cipher",
                        optprefix ? optprefix : "");
             return -1;
         }
         return qcrypto_block_qcow_init(block, options->u.qcow.key_secret,
                                        n_threads, errp);
     }
 }
 
 
 static int
 qcrypto_block_qcow_create(QCryptoBlock *block,
                           QCryptoBlockCreateOptions *options,
                           const char *optprefix,
                           QCryptoBlockInitFunc initfunc G_GNUC_UNUSED,
                           QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED,
                           void *opaque G_GNUC_UNUSED,
                           Error **errp)
 {
     if (!options->u.qcow.key_secret) {
         error_setg(errp, "Parameter '%skey-secret' is required for cipher",
                    optprefix ? optprefix : "");
         return -1;
     }
     /* QCow2 has no special header, since everything is hardwired */
     return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, 1, errp);
 }
 
 
 static void
 qcrypto_block_qcow_cleanup(QCryptoBlock *block)
 {
 }
 
 
 static int
 qcrypto_block_qcow_decrypt(QCryptoBlock *block,
                            uint64_t offset,
                            uint8_t *buf,
                            size_t len,
                            Error **errp)
 {
     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
     return qcrypto_block_decrypt_helper(block,
                                         QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
                                         offset, buf, len, errp);
 }
 
 
 static int
 qcrypto_block_qcow_encrypt(QCryptoBlock *block,
                            uint64_t offset,
                            uint8_t *buf,
                            size_t len,
                            Error **errp)
 {
     assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
     assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
     return qcrypto_block_encrypt_helper(block,
                                         QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
                                         offset, buf, len, errp);
 }
 
 
 const QCryptoBlockDriver qcrypto_block_driver_qcow = {
     .open = qcrypto_block_qcow_open,
     .create = qcrypto_block_qcow_create,
     .cleanup = qcrypto_block_qcow_cleanup,
     .decrypt = qcrypto_block_qcow_decrypt,
     .encrypt = qcrypto_block_qcow_encrypt,
     .has_format = qcrypto_block_qcow_has_format,
 };