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 2.1 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 #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  * @n_threads: allow concurrent I/O from up to @n_threads threads
  79  * @errp: pointer to a NULL-initialized error object
  80  *
  81  * Create a new block encryption object for an existing
  82  * storage volume encrypted with format identified by
  83  * the parameters in @options.
  84  *
  85  * This will use @readfunc to initialize the encryption
  86  * context based on the volume header(s), extracting the
  87  * master key(s) as required.
  88  *
  89  * If @flags contains QCRYPTO_BLOCK_OPEN_NO_IO then
  90  * the open process will be optimized to skip any parts
  91  * that are only required to perform I/O. In particular
  92  * this would usually avoid the need to decrypt any
  93  * master keys. The only thing that can be done with
  94  * the resulting QCryptoBlock object would be to query
  95  * metadata such as the payload offset. There will be
  96  * no cipher or ivgen objects available.
  97  *
  98  * If any part of initializing the encryption context
  99  * fails an error will be returned. This could be due
 100  * to the volume being in the wrong format, a cipher
 101  * or IV generator algorithm that is not supported,
 102  * or incorrect passphrases.
 103  *
 104  * Returns: a block encryption format, or NULL on error
 105  */
 106 QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
 107                                  const char *optprefix,
 108                                  QCryptoBlockReadFunc readfunc,
 109                                  void *opaque,
 110                                  unsigned int flags,
 111                                  size_t n_threads,
 112                                  Error **errp);
 113
 114 /**
 115  * qcrypto_block_create:
 116  * @options: the encryption options
 117  * @optprefix: name prefix for options
 118  * @initfunc: callback for initializing volume header
 119  * @writefunc: callback for writing data to the volume header
 120  * @opaque: data to pass to @initfunc and @writefunc
 121  * @errp: pointer to a NULL-initialized error object
 122  *
 123  * Create a new block encryption object for initializing
 124  * a storage volume to be encrypted with format identified
 125  * by the parameters in @options.
 126  *
 127  * This method will allocate space for a new volume header
 128  * using @initfunc and then write header data using @writefunc,
 129  * generating new master keys, etc as required. Any existing
 130  * data present on the volume will be irrevocably destroyed.
 131  *
 132  * If any part of initializing the encryption context
 133  * fails an error will be returned. This could be due
 134  * to the volume being in the wrong format, a cipher
 135  * or IV generator algorithm that is not supported,
 136  * or incorrect passphrases.
 137  *
 138  * Returns: a block encryption format, or NULL on error
 139  */
 140 QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
 141                                    const char *optprefix,
 142                                    QCryptoBlockInitFunc initfunc,
 143                                    QCryptoBlockWriteFunc writefunc,
 144                                    void *opaque,
 145                                    Error **errp);
 146
 147 /**
 148  * qcrypto_block_amend_options:
 149  * @block: the block encryption object
 150  *
 151  * @readfunc: callback for reading data from the volume header
 152  * @writefunc: callback for writing data to the volume header
 153  * @opaque: data to pass to @readfunc and @writefunc
 154  * @options: the new/amended encryption options
 155  * @force: hint for the driver to allow unsafe operation
 156  * @errp: error pointer
 157  *
 158  * Changes the crypto options of the encryption format
 159  *
 160  */
 161 int qcrypto_block_amend_options(QCryptoBlock *block,
 162                                 QCryptoBlockReadFunc readfunc,
 163                                 QCryptoBlockWriteFunc writefunc,
 164                                 void *opaque,
 165                                 QCryptoBlockAmendOptions *options,
 166                                 bool force,
 167                                 Error **errp);
 168
 169
 170 /**
 171  * qcrypto_block_calculate_payload_offset:
 172  * @create_opts: the encryption options
 173  * @optprefix: name prefix for options
 174  * @len: output for number of header bytes before payload
 175  * @errp: pointer to a NULL-initialized error object
 176  *
 177  * Calculate the number of header bytes before the payload in an encrypted
 178  * storage volume.  The header is an area before the payload that is reserved
 179  * for encryption metadata.
 180  *
 181  * Returns: true on success, false on error
 182  */
 183 bool
 184 qcrypto_block_calculate_payload_offset(QCryptoBlockCreateOptions *create_opts,
 185                                        const char *optprefix,
 186                                        size_t *len,
 187                                        Error **errp);
 188
 189
 190 /**
 191  * qcrypto_block_get_info:
 192  * @block: the block encryption object
 193  * @errp: pointer to a NULL-initialized error object
 194  *
 195  * Get information about the configuration options for the
 196  * block encryption object. This includes details such as
 197  * the cipher algorithms, modes, and initialization vector
 198  * generators.
 199  *
 200  * Returns: a block encryption info object, or NULL on error
 201  */
 202 QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
 203                                          Error **errp);
 204
 205 /**
 206  * @qcrypto_block_decrypt:
 207  * @block: the block encryption object
 208  * @offset: the position at which @iov was read
 209  * @buf: the buffer to decrypt
 210  * @len: the length of @buf in bytes
 211  * @errp: pointer to a NULL-initialized error object
 212  *
 213  * Decrypt @len bytes of cipher text in @buf, writing
 214  * plain text back into @buf. @len and @offset must be
 215  * a multiple of the encryption format sector size.
 216  *
 217  * Returns 0 on success, -1 on failure
 218  */
 219 int qcrypto_block_decrypt(QCryptoBlock *block,
 220                           uint64_t offset,
 221                           uint8_t *buf,
 222                           size_t len,
 223                           Error **errp);
 224
 225 /**
 226  * @qcrypto_block_encrypt:
 227  * @block: the block encryption object
 228  * @offset: the position at which @iov will be written
 229  * @buf: the buffer to decrypt
 230  * @len: the length of @buf in bytes
 231  * @errp: pointer to a NULL-initialized error object
 232  *
 233  * Encrypt @len bytes of plain text in @buf, writing
 234  * cipher text back into @buf. @len and @offset must be
 235  * a multiple of the encryption format sector size.
 236  *
 237  * Returns 0 on success, -1 on failure
 238  */
 239 int qcrypto_block_encrypt(QCryptoBlock *block,
 240                           uint64_t offset,
 241                           uint8_t *buf,
 242                           size_t len,
 243                           Error **errp);
 244
 245 /**
 246  * qcrypto_block_get_cipher:
 247  * @block: the block encryption object
 248  *
 249  * Get the cipher to use for payload encryption
 250  *
 251  * Returns: the cipher object
 252  */
 253 QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block);
 254
 255 /**
 256  * qcrypto_block_get_ivgen:
 257  * @block: the block encryption object
 258  *
 259  * Get the initialization vector generator to use for
 260  * payload encryption
 261  *
 262  * Returns: the IV generator object
 263  */
 264 QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block);
 265
 266
 267 /**
 268  * qcrypto_block_get_kdf_hash:
 269  * @block: the block encryption object
 270  *
 271  * Get the hash algorithm used with the key derivation
 272  * function
 273  *
 274  * Returns: the hash algorithm
 275  */
 276 QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block);
 277
 278 /**
 279  * qcrypto_block_get_payload_offset:
 280  * @block: the block encryption object
 281  *
 282  * Get the offset to the payload indicated by the
 283  * encryption header, in bytes.
 284  *
 285  * Returns: the payload offset in bytes
 286  */
 287 uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block);
 288
 289 /**
 290  * qcrypto_block_get_sector_size:
 291  * @block: the block encryption object
 292  *
 293  * Get the size of sectors used for payload encryption. A new
 294  * IV is used at the start of each sector. The encryption
 295  * sector size is not required to match the sector size of the
 296  * underlying storage. For example LUKS will always use a 512
 297  * byte sector size, even if the volume is on a disk with 4k
 298  * sectors.
 299  *
 300  * Returns: the sector in bytes
 301  */
 302 uint64_t qcrypto_block_get_sector_size(QCryptoBlock *block);
 303
 304 /**
 305  * qcrypto_block_free:
 306  * @block: the block encryption object
 307  *
 308  * Release all resources associated with the encryption
 309  * object
 310  */
 311 void qcrypto_block_free(QCryptoBlock *block);
 312
 313 G_DEFINE_AUTOPTR_CLEANUP_FUNC(QCryptoBlock, qcrypto_block_free)
 314
 315 #endif /* QCRYPTO_BLOCK_H */