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/*
* QEMU Crypto block device encryption
*
* 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 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/>.
*
*/
#ifndef QCRYPTO_BLOCK_H__
#define QCRYPTO_BLOCK_H__
#include "crypto/cipher.h"
#include "crypto/ivgen.h"
typedef struct QCryptoBlock QCryptoBlock;
/* See also QCryptoBlockFormat, QCryptoBlockCreateOptions
* and QCryptoBlockOpenOptions in qapi/crypto.json */
typedef ssize_t (*QCryptoBlockReadFunc)(QCryptoBlock *block,
size_t offset,
uint8_t *buf,
size_t buflen,
Error **errp,
void *opaque);
typedef ssize_t (*QCryptoBlockInitFunc)(QCryptoBlock *block,
size_t headerlen,
Error **errp,
void *opaque);
typedef ssize_t (*QCryptoBlockWriteFunc)(QCryptoBlock *block,
size_t offset,
const uint8_t *buf,
size_t buflen,
Error **errp,
void *opaque);
/**
* qcrypto_block_has_format:
* @format: the encryption format
* @buf: the data from head of the volume
* @len: the length of @buf in bytes
*
* Given @len bytes of data from the head of a storage volume
* in @buf, probe to determine if the volume has the encryption
* format specified in @format.
*
* Returns: true if the data in @buf matches @format
*/
bool qcrypto_block_has_format(QCryptoBlockFormat format,
const uint8_t *buf,
size_t buflen);
typedef enum {
QCRYPTO_BLOCK_OPEN_NO_IO = (1 << 0),
} QCryptoBlockOpenFlags;
/**
* qcrypto_block_open:
* @options: the encryption options
* @readfunc: callback for reading data from the volume
* @opaque: data to pass to @readfunc
* @flags: bitmask of QCryptoBlockOpenFlags values
* @errp: pointer to a NULL-initialized error object
*
* Create a new block encryption object for an existing
* storage volume encrypted with format identified by
* the parameters in @options.
*
* This will use @readfunc to initialize the encryption
* context based on the volume header(s), extracting the
* master key(s) as required.
*
* If @flags contains QCRYPTO_BLOCK_OPEN_NO_IO then
* the open process will be optimized to skip any parts
* that are only required to perform I/O. In particular
* this would usually avoid the need to decrypt any
* master keys. The only thing that can be done with
* the resulting QCryptoBlock object would be to query
* metadata such as the payload offset. There will be
* no cipher or ivgen objects available.
*
* If any part of initializing the encryption context
* fails an error will be returned. This could be due
* to the volume being in the wrong format, a cipher
* or IV generator algorithm that is not supported,
* or incorrect passphrases.
*
* Returns: a block encryption format, or NULL on error
*/
QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
QCryptoBlockReadFunc readfunc,
void *opaque,
unsigned int flags,
Error **errp);
/**
* qcrypto_block_create:
* @format: the encryption format
* @initfunc: callback for initializing volume header
* @writefunc: callback for writing data to the volume header
* @opaque: data to pass to @initfunc and @writefunc
* @errp: pointer to a NULL-initialized error object
*
* Create a new block encryption object for initializing
* a storage volume to be encrypted with format identified
* by the parameters in @options.
*
* This method will allocate space for a new volume header
* using @initfunc and then write header data using @writefunc,
* generating new master keys, etc as required. Any existing
* data present on the volume will be irrevocably destroyed.
*
* If any part of initializing the encryption context
* fails an error will be returned. This could be due
* to the volume being in the wrong format, a cipher
* or IV generator algorithm that is not supported,
* or incorrect passphrases.
*
* Returns: a block encryption format, or NULL on error
*/
QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
QCryptoBlockInitFunc initfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp);
/**
* @qcrypto_block_decrypt:
* @block: the block encryption object
* @startsector: the sector from which @buf was read
* @buf: the buffer to decrypt
* @len: the length of @buf in bytes
* @errp: pointer to a NULL-initialized error object
*
* Decrypt @len bytes of cipher text in @buf, writing
* plain text back into @buf
*
* Returns 0 on success, -1 on failure
*/
int qcrypto_block_decrypt(QCryptoBlock *block,
uint64_t startsector,
uint8_t *buf,
size_t len,
Error **errp);
/**
* @qcrypto_block_encrypt:
* @block: the block encryption object
* @startsector: the sector to which @buf will be written
* @buf: the buffer to decrypt
* @len: the length of @buf in bytes
* @errp: pointer to a NULL-initialized error object
*
* Encrypt @len bytes of plain text in @buf, writing
* cipher text back into @buf
*
* Returns 0 on success, -1 on failure
*/
int qcrypto_block_encrypt(QCryptoBlock *block,
uint64_t startsector,
uint8_t *buf,
size_t len,
Error **errp);
/**
* qcrypto_block_get_cipher:
* @block: the block encryption object
*
* Get the cipher to use for payload encryption
*
* Returns: the cipher object
*/
QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block);
/**
* qcrypto_block_get_ivgen:
* @block: the block encryption object
*
* Get the initialization vector generator to use for
* payload encryption
*
* Returns: the IV generator object
*/
QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block);
/**
* qcrypto_block_get_kdf_hash:
* @block: the block encryption object
*
* Get the hash algorithm used with the key derivation
* function
*
* Returns: the hash algorithm
*/
QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block);
/**
* qcrypto_block_get_payload_offset:
* @block: the block encryption object
*
* Get the offset to the payload indicated by the
* encryption header, in bytes.
*
* Returns: the payload offset in bytes
*/
uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block);
/**
* qcrypto_block_free:
* @block: the block encryption object
*
* Release all resources associated with the encryption
* object
*/
void qcrypto_block_free(QCryptoBlock *block);
#endif /* QCRYPTO_BLOCK_H__ */
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