include/crypto/block.h

   1 /*
   2  * QEMU Crypto block device encryption
   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 #ifndef QCRYPTO_BLOCK_H
  22 #define QCRYPTO_BLOCK_H
  23
  24 #include "crypto/cipher.h"
  25 #include "crypto/ivgen.h"
  26
  27 typedef struct QCryptoBlock QCryptoBlock;
  28
  29 /* See also QCryptoBlockFormat, QCryptoBlockCreateOptions
  30  * and QCryptoBlockOpenOptions in qapi/crypto.json */
  31
  32 typedef ssize_t (*QCryptoBlockReadFunc)(QCryptoBlock *block,
  33                                         size_t offset,
  34                                         uint8_t *buf,
  35                                         size_t buflen,
  36                                         void *opaque,
  37                                         Error **errp);
  38
  39 typedef ssize_t (*QCryptoBlockInitFunc)(QCryptoBlock *block,
  40                                         size_t headerlen,
  41                                         void *opaque,
  42                                         Error **errp);
  43
  44 typedef ssize_t (*QCryptoBlockWriteFunc)(QCryptoBlock *block,
  45                                          size_t offset,
  46                                          const uint8_t *buf,
  47                                          size_t buflen,
  48                                          void *opaque,
  49                                          Error **errp);
  50
  51 /**
  52  * qcrypto_block_has_format:
  53  * @format: the encryption format
  54  * @buf: the data from head of the volume
  55  * @len: the length of @buf in bytes
  56  *
  57  * Given @len bytes of data from the head of a storage volume
  58  * in @buf, probe to determine if the volume has the encryption
  59  * format specified in @format.
  60  *
  61  * Returns: true if the data in @buf matches @format
  62  */
  63 bool qcrypto_block_has_format(QCryptoBlockFormat format,
  64                               const uint8_t *buf,
  65                               size_t buflen);
  66
  67 typedef enum {
  68     QCRYPTO_BLOCK_OPEN_NO_IO = (1 << 0),
  69 } QCryptoBlockOpenFlags;
  70
  71 /**
  72  * qcrypto_block_open:
  73  * @options: the encryption options
  74  * @optprefix: name prefix for options
  75  * @readfunc: callback for reading data from the volume
  76  * @opaque: data to pass to @readfunc
  77  * @flags: bitmask of QCryptoBlockOpenFlags values
  78  * @errp: pointer to a NULL-initialized error object
  79  *
  80  * Create a new block encryption object for an existing
  81  * storage volume encrypted with format identified by
  82  * the parameters in @options.
  83  *
  84  * This will use @readfunc to initialize the encryption
  85  * context based on the volume header(s), extracting the
  86  * master key(s) as required.
  87  *
  88  * If @flags contains QCRYPTO_BLOCK_OPEN_NO_IO then
  89  * the open process will be optimized to skip any parts
  90  * that are only required to perform I/O. In particular
  91  * this would usually avoid the need to decrypt any
  92  * master keys. The only thing that can be done with
  93  * the resulting QCryptoBlock object would be to query
  94  * metadata such as the payload offset. There will be
  95  * no cipher or ivgen objects available.
  96  *
  97  * If any part of initializing the encryption context
  98  * fails an error will be returned. This could be due
  99  * to the volume being in the wrong format, a cipher
 100  * or IV generator algorithm that is not supported,
 101  * or incorrect passphrases.
 102  *
 103  * Returns: a block encryption format, or NULL on error
 104  */
 105 QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
 106                                  const char *optprefix,
 107                                  QCryptoBlockReadFunc readfunc,
 108                                  void *opaque,
 109                                  unsigned int flags,
 110                                  Error **errp);
 111
 112 /**
 113  * qcrypto_block_create:
 114  * @options: the encryption options
 115  * @optprefix: name prefix for options
 116  * @initfunc: callback for initializing volume header
 117  * @writefunc: callback for writing data to the volume header
 118  * @opaque: data to pass to @initfunc and @writefunc
 119  * @errp: pointer to a NULL-initialized error object
 120  *
 121  * Create a new block encryption object for initializing
 122  * a storage volume to be encrypted with format identified
 123  * by the parameters in @options.
 124  *
 125  * This method will allocate space for a new volume header
 126  * using @initfunc and then write header data using @writefunc,
 127  * generating new master keys, etc as required. Any existing
 128  * data present on the volume will be irrevocably destroyed.
 129  *
 130  * If any part of initializing the encryption context
 131  * fails an error will be returned. This could be due
 132  * to the volume being in the wrong format, a cipher
 133  * or IV generator algorithm that is not supported,
 134  * or incorrect passphrases.
 135  *
 136  * Returns: a block encryption format, or NULL on error
 137  */
 138 QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
 139                                    const char *optprefix,
 140                                    QCryptoBlockInitFunc initfunc,
 141                                    QCryptoBlockWriteFunc writefunc,
 142                                    void *opaque,
 143                                    Error **errp);
 144
 145
 146 /**
 147  * qcrypto_block_get_info:
 148  * @block: the block encryption object
 149  * @errp: pointer to a NULL-initialized error object
 150  *
 151  * Get information about the configuration options for the
 152  * block encryption object. This includes details such as
 153  * the cipher algorithms, modes, and initialization vector
 154  * generators.
 155  *
 156  * Returns: a block encryption info object, or NULL on error
 157  */
 158 QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
 159                                          Error **errp);
 160
 161 /**
 162  * @qcrypto_block_decrypt:
 163  * @block: the block encryption object
 164  * @offset: the position at which @iov was read
 165  * @buf: the buffer to decrypt
 166  * @len: the length of @buf in bytes
 167  * @errp: pointer to a NULL-initialized error object
 168  *
 169  * Decrypt @len bytes of cipher text in @buf, writing
 170  * plain text back into @buf. @len and @offset must be
 171  * a multiple of the encryption format sector size.
 172  *
 173  * Returns 0 on success, -1 on failure
 174  */
 175 int qcrypto_block_decrypt(QCryptoBlock *block,
 176                           uint64_t offset,
 177                           uint8_t *buf,
 178                           size_t len,
 179                           Error **errp);
 180
 181 /**
 182  * @qcrypto_block_encrypt:
 183  * @block: the block encryption object
 184  * @offset: the position at which @iov will be written
 185  * @buf: the buffer to decrypt
 186  * @len: the length of @buf in bytes
 187  * @errp: pointer to a NULL-initialized error object
 188  *
 189  * Encrypt @len bytes of plain text in @buf, writing
 190  * cipher text back into @buf. @len and @offset must be
 191  * a multiple of the encryption format sector size.
 192  *
 193  * Returns 0 on success, -1 on failure
 194  */
 195 int qcrypto_block_encrypt(QCryptoBlock *block,
 196                           uint64_t offset,
 197                           uint8_t *buf,
 198                           size_t len,
 199                           Error **errp);
 200
 201 /**
 202  * qcrypto_block_get_cipher:
 203  * @block: the block encryption object
 204  *
 205  * Get the cipher to use for payload encryption
 206  *
 207  * Returns: the cipher object
 208  */
 209 QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block);
 210
 211 /**
 212  * qcrypto_block_get_ivgen:
 213  * @block: the block encryption object
 214  *
 215  * Get the initialization vector generator to use for
 216  * payload encryption
 217  *
 218  * Returns: the IV generator object
 219  */
 220 QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block);
 221
 222
 223 /**
 224  * qcrypto_block_get_kdf_hash:
 225  * @block: the block encryption object
 226  *
 227  * Get the hash algorithm used with the key derivation
 228  * function
 229  *
 230  * Returns: the hash algorithm
 231  */
 232 QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block);
 233
 234 /**
 235  * qcrypto_block_get_payload_offset:
 236  * @block: the block encryption object
 237  *
 238  * Get the offset to the payload indicated by the
 239  * encryption header, in bytes.
 240  *
 241  * Returns: the payload offset in bytes
 242  */
 243 uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block);
 244
 245 /**
 246  * qcrypto_block_get_sector_size:
 247  * @block: the block encryption object
 248  *
 249  * Get the size of sectors used for payload encryption. A new
 250  * IV is used at the start of each sector. The encryption
 251  * sector size is not required to match the sector size of the
 252  * underlying storage. For example LUKS will always use a 512
 253  * byte sector size, even if the volume is on a disk with 4k
 254  * sectors.
 255  *
 256  * Returns: the sector in bytes
 257  */
 258 uint64_t qcrypto_block_get_sector_size(QCryptoBlock *block);
 259
 260 /**
 261  * qcrypto_block_free:
 262  * @block: the block encryption object
 263  *
 264  * Release all resources associated with the encryption
 265  * object
 266  */
 267 void qcrypto_block_free(QCryptoBlock *block);
 268
 269 #endif /* QCRYPTO_BLOCK_H */