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 * @startsector: the sector from which @buf 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 171 * 172 * Returns 0 on success, -1 on failure 173 */ 174 int qcrypto_block_decrypt(QCryptoBlock *block, 175 uint64_t startsector, 176 uint8_t *buf, 177 size_t len, 178 Error **errp); 179 180 /** 181 * @qcrypto_block_encrypt: 182 * @block: the block encryption object 183 * @startsector: the sector to which @buf will be written 184 * @buf: the buffer to decrypt 185 * @len: the length of @buf in bytes 186 * @errp: pointer to a NULL-initialized error object 187 * 188 * Encrypt @len bytes of plain text in @buf, writing 189 * cipher text back into @buf 190 * 191 * Returns 0 on success, -1 on failure 192 */ 193 int qcrypto_block_encrypt(QCryptoBlock *block, 194 uint64_t startsector, 195 uint8_t *buf, 196 size_t len, 197 Error **errp); 198 199 /** 200 * qcrypto_block_get_cipher: 201 * @block: the block encryption object 202 * 203 * Get the cipher to use for payload encryption 204 * 205 * Returns: the cipher object 206 */ 207 QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block); 208 209 /** 210 * qcrypto_block_get_ivgen: 211 * @block: the block encryption object 212 * 213 * Get the initialization vector generator to use for 214 * payload encryption 215 * 216 * Returns: the IV generator object 217 */ 218 QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block); 219 220 221 /** 222 * qcrypto_block_get_kdf_hash: 223 * @block: the block encryption object 224 * 225 * Get the hash algorithm used with the key derivation 226 * function 227 * 228 * Returns: the hash algorithm 229 */ 230 QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block); 231 232 /** 233 * qcrypto_block_get_payload_offset: 234 * @block: the block encryption object 235 * 236 * Get the offset to the payload indicated by the 237 * encryption header, in bytes. 238 * 239 * Returns: the payload offset in bytes 240 */ 241 uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block); 242 243 /** 244 * qcrypto_block_free: 245 * @block: the block encryption object 246 * 247 * Release all resources associated with the encryption 248 * object 249 */ 250 void qcrypto_block_free(QCryptoBlock *block); 251 252 #endif /* QCRYPTO_BLOCK_H */ 253