| 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 | #include "qemu/osdep.h" |
| 22 | #include "qapi/error.h" |
| 23 | #include "qemu/lockable.h" |
| 24 | #include "blockpriv.h" |
| 25 | #include "block-qcow.h" |
| 26 | #include "block-luks.h" |
| 27 | |
| 28 | static const QCryptoBlockDriver *qcrypto_block_drivers[] = { |
| 29 | [QCRYPTO_BLOCK_FORMAT_QCOW] = &qcrypto_block_driver_qcow, |
| 30 | [QCRYPTO_BLOCK_FORMAT_LUKS] = &qcrypto_block_driver_luks, |
| 31 | }; |
| 32 | |
| 33 | |
| 34 | bool qcrypto_block_has_format(QCryptoBlockFormat format, |
| 35 | const uint8_t *buf, |
| 36 | size_t len) |
| 37 | { |
| 38 | const QCryptoBlockDriver *driver; |
| 39 | |
| 40 | if (format >= G_N_ELEMENTS(qcrypto_block_drivers) || |
| 41 | !qcrypto_block_drivers[format]) { |
| 42 | return false; |
| 43 | } |
| 44 | |
| 45 | driver = qcrypto_block_drivers[format]; |
| 46 | |
| 47 | return driver->has_format(buf, len); |
| 48 | } |
| 49 | |
| 50 | |
| 51 | QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options, |
| 52 | const char *optprefix, |
| 53 | QCryptoBlockReadFunc readfunc, |
| 54 | void *opaque, |
| 55 | unsigned int flags, |
| 56 | Error **errp) |
| 57 | { |
| 58 | QCryptoBlock *block = g_new0(QCryptoBlock, 1); |
| 59 | |
| 60 | qemu_mutex_init(&block->mutex); |
| 61 | |
| 62 | block->format = options->format; |
| 63 | |
| 64 | if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) || |
| 65 | !qcrypto_block_drivers[options->format]) { |
| 66 | error_setg(errp, "Unsupported block driver %s", |
| 67 | QCryptoBlockFormat_str(options->format)); |
| 68 | g_free(block); |
| 69 | return NULL; |
| 70 | } |
| 71 | |
| 72 | block->driver = qcrypto_block_drivers[options->format]; |
| 73 | |
| 74 | if (block->driver->open(block, options, optprefix, |
| 75 | readfunc, opaque, flags, errp) < 0) |
| 76 | { |
| 77 | g_free(block); |
| 78 | return NULL; |
| 79 | } |
| 80 | |
| 81 | return block; |
| 82 | } |
| 83 | |
| 84 | |
| 85 | QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options, |
| 86 | const char *optprefix, |
| 87 | QCryptoBlockInitFunc initfunc, |
| 88 | QCryptoBlockWriteFunc writefunc, |
| 89 | void *opaque, |
| 90 | unsigned int flags, |
| 91 | Error **errp) |
| 92 | { |
| 93 | QCryptoBlock *block = g_new0(QCryptoBlock, 1); |
| 94 | |
| 95 | qemu_mutex_init(&block->mutex); |
| 96 | |
| 97 | block->format = options->format; |
| 98 | |
| 99 | if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) || |
| 100 | !qcrypto_block_drivers[options->format]) { |
| 101 | error_setg(errp, "Unsupported block driver %s", |
| 102 | QCryptoBlockFormat_str(options->format)); |
| 103 | g_free(block); |
| 104 | return NULL; |
| 105 | } |
| 106 | |
| 107 | block->driver = qcrypto_block_drivers[options->format]; |
| 108 | block->detached_header = flags & QCRYPTO_BLOCK_CREATE_DETACHED; |
| 109 | |
| 110 | if (block->driver->create(block, options, optprefix, initfunc, |
| 111 | writefunc, opaque, errp) < 0) { |
| 112 | g_free(block); |
| 113 | return NULL; |
| 114 | } |
| 115 | |
| 116 | return block; |
| 117 | } |
| 118 | |
| 119 | |
| 120 | static int qcrypto_block_headerlen_hdr_init_func(QCryptoBlock *block, |
| 121 | size_t headerlen, void *opaque, Error **errp) |
| 122 | { |
| 123 | size_t *headerlenp = opaque; |
| 124 | |
| 125 | /* Stash away the payload size */ |
| 126 | *headerlenp = headerlen; |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | |
| 131 | static int qcrypto_block_headerlen_hdr_write_func(QCryptoBlock *block, |
| 132 | size_t offset, const uint8_t *buf, size_t buflen, |
| 133 | void *opaque, Error **errp) |
| 134 | { |
| 135 | /* Discard the bytes, we're not actually writing to an image */ |
| 136 | return 0; |
| 137 | } |
| 138 | |
| 139 | |
| 140 | bool |
| 141 | qcrypto_block_calculate_payload_offset(QCryptoBlockCreateOptions *create_opts, |
| 142 | const char *optprefix, |
| 143 | size_t *len, |
| 144 | Error **errp) |
| 145 | { |
| 146 | /* Fake LUKS creation in order to determine the payload size */ |
| 147 | g_autoptr(QCryptoBlock) crypto = |
| 148 | qcrypto_block_create(create_opts, optprefix, |
| 149 | qcrypto_block_headerlen_hdr_init_func, |
| 150 | qcrypto_block_headerlen_hdr_write_func, |
| 151 | len, 0, errp); |
| 152 | return crypto != NULL; |
| 153 | } |
| 154 | |
| 155 | int qcrypto_block_amend_options(QCryptoBlock *block, |
| 156 | QCryptoBlockReadFunc readfunc, |
| 157 | QCryptoBlockWriteFunc writefunc, |
| 158 | void *opaque, |
| 159 | QCryptoBlockAmendOptions *options, |
| 160 | bool force, |
| 161 | Error **errp) |
| 162 | { |
| 163 | if (options->format != block->format) { |
| 164 | error_setg(errp, |
| 165 | "Cannot amend encryption format"); |
| 166 | return -1; |
| 167 | } |
| 168 | |
| 169 | if (!block->driver->amend) { |
| 170 | error_setg(errp, |
| 171 | "Crypto format %s doesn't support format options amendment", |
| 172 | QCryptoBlockFormat_str(block->format)); |
| 173 | return -1; |
| 174 | } |
| 175 | |
| 176 | return block->driver->amend(block, |
| 177 | readfunc, |
| 178 | writefunc, |
| 179 | opaque, |
| 180 | options, |
| 181 | force, |
| 182 | errp); |
| 183 | } |
| 184 | |
| 185 | QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block, |
| 186 | Error **errp) |
| 187 | { |
| 188 | QCryptoBlockInfo *info = g_new0(QCryptoBlockInfo, 1); |
| 189 | |
| 190 | info->format = block->format; |
| 191 | |
| 192 | if (block->driver->get_info && |
| 193 | block->driver->get_info(block, info, errp) < 0) { |
| 194 | g_free(info); |
| 195 | return NULL; |
| 196 | } |
| 197 | |
| 198 | return info; |
| 199 | } |
| 200 | |
| 201 | |
| 202 | int qcrypto_block_decrypt(QCryptoBlock *block, |
| 203 | uint64_t offset, |
| 204 | uint8_t *buf, |
| 205 | size_t len, |
| 206 | Error **errp) |
| 207 | { |
| 208 | return block->driver->decrypt(block, offset, buf, len, errp); |
| 209 | } |
| 210 | |
| 211 | |
| 212 | int qcrypto_block_encrypt(QCryptoBlock *block, |
| 213 | uint64_t offset, |
| 214 | uint8_t *buf, |
| 215 | size_t len, |
| 216 | Error **errp) |
| 217 | { |
| 218 | return block->driver->encrypt(block, offset, buf, len, errp); |
| 219 | } |
| 220 | |
| 221 | |
| 222 | QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block) |
| 223 | { |
| 224 | /* Ciphers should be accessed through pop/push method to be thread-safe. |
| 225 | * Better, they should not be accessed externally at all (note, that |
| 226 | * pop/push are static functions) |
| 227 | * This function is used only in test with one thread (it's safe to skip |
| 228 | * pop/push interface), so it's enough to assert it here: |
| 229 | */ |
| 230 | assert(block->max_free_ciphers <= 1); |
| 231 | return block->free_ciphers ? block->free_ciphers[0] : NULL; |
| 232 | } |
| 233 | |
| 234 | |
| 235 | static QCryptoCipher *qcrypto_block_pop_cipher(QCryptoBlock *block, |
| 236 | Error **errp) |
| 237 | { |
| 238 | /* Usually there is a free cipher available */ |
| 239 | WITH_QEMU_LOCK_GUARD(&block->mutex) { |
| 240 | if (block->n_free_ciphers > 0) { |
| 241 | block->n_free_ciphers--; |
| 242 | return block->free_ciphers[block->n_free_ciphers]; |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | /* Otherwise allocate a new cipher */ |
| 247 | return qcrypto_cipher_new(block->alg, block->mode, block->key, |
| 248 | block->nkey, errp); |
| 249 | } |
| 250 | |
| 251 | |
| 252 | static void qcrypto_block_push_cipher(QCryptoBlock *block, |
| 253 | QCryptoCipher *cipher) |
| 254 | { |
| 255 | QEMU_LOCK_GUARD(&block->mutex); |
| 256 | |
| 257 | if (block->n_free_ciphers == block->max_free_ciphers) { |
| 258 | block->max_free_ciphers++; |
| 259 | block->free_ciphers = g_renew(QCryptoCipher *, |
| 260 | block->free_ciphers, |
| 261 | block->max_free_ciphers); |
| 262 | } |
| 263 | |
| 264 | block->free_ciphers[block->n_free_ciphers] = cipher; |
| 265 | block->n_free_ciphers++; |
| 266 | } |
| 267 | |
| 268 | |
| 269 | int qcrypto_block_init_cipher(QCryptoBlock *block, |
| 270 | QCryptoCipherAlgo alg, |
| 271 | QCryptoCipherMode mode, |
| 272 | const uint8_t *key, size_t nkey, |
| 273 | Error **errp) |
| 274 | { |
| 275 | QCryptoCipher *cipher; |
| 276 | |
| 277 | assert(!block->free_ciphers && !block->max_free_ciphers && |
| 278 | !block->n_free_ciphers); |
| 279 | |
| 280 | /* Stash away cipher parameters for qcrypto_block_pop_cipher() */ |
| 281 | block->alg = alg; |
| 282 | block->mode = mode; |
| 283 | block->key = g_memdup2(key, nkey); |
| 284 | block->nkey = nkey; |
| 285 | |
| 286 | /* |
| 287 | * Create a new cipher to validate the parameters now. This reduces the |
| 288 | * chance of cipher creation failing at I/O time. |
| 289 | */ |
| 290 | cipher = qcrypto_block_pop_cipher(block, errp); |
| 291 | if (!cipher) { |
| 292 | g_free(block->key); |
| 293 | block->key = NULL; |
| 294 | return -1; |
| 295 | } |
| 296 | |
| 297 | qcrypto_block_push_cipher(block, cipher); |
| 298 | return 0; |
| 299 | } |
| 300 | |
| 301 | |
| 302 | void qcrypto_block_free_cipher(QCryptoBlock *block) |
| 303 | { |
| 304 | size_t i; |
| 305 | |
| 306 | g_free(block->key); |
| 307 | block->key = NULL; |
| 308 | |
| 309 | if (!block->free_ciphers) { |
| 310 | return; |
| 311 | } |
| 312 | |
| 313 | /* All popped ciphers were eventually pushed back */ |
| 314 | assert(block->n_free_ciphers == block->max_free_ciphers); |
| 315 | |
| 316 | for (i = 0; i < block->max_free_ciphers; i++) { |
| 317 | qcrypto_cipher_free(block->free_ciphers[i]); |
| 318 | } |
| 319 | |
| 320 | g_free(block->free_ciphers); |
| 321 | block->free_ciphers = NULL; |
| 322 | block->max_free_ciphers = block->n_free_ciphers = 0; |
| 323 | } |
| 324 | |
| 325 | QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block) |
| 326 | { |
| 327 | /* ivgen should be accessed under mutex. However, this function is used only |
| 328 | * in test with one thread, so it's enough to assert it here: |
| 329 | */ |
| 330 | assert(block->max_free_ciphers <= 1); |
| 331 | return block->ivgen; |
| 332 | } |
| 333 | |
| 334 | |
| 335 | QCryptoHashAlgo qcrypto_block_get_kdf_hash(QCryptoBlock *block) |
| 336 | { |
| 337 | return block->kdfhash; |
| 338 | } |
| 339 | |
| 340 | |
| 341 | uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block) |
| 342 | { |
| 343 | return block->payload_offset; |
| 344 | } |
| 345 | |
| 346 | |
| 347 | uint64_t qcrypto_block_get_sector_size(QCryptoBlock *block) |
| 348 | { |
| 349 | return block->sector_size; |
| 350 | } |
| 351 | |
| 352 | |
| 353 | void qcrypto_block_free(QCryptoBlock *block) |
| 354 | { |
| 355 | if (!block) { |
| 356 | return; |
| 357 | } |
| 358 | |
| 359 | block->driver->cleanup(block); |
| 360 | |
| 361 | qcrypto_block_free_cipher(block); |
| 362 | qcrypto_ivgen_free(block->ivgen); |
| 363 | qemu_mutex_destroy(&block->mutex); |
| 364 | g_free(block); |
| 365 | } |
| 366 | |
| 367 | |
| 368 | typedef int (*QCryptoCipherEncDecFunc)(QCryptoCipher *cipher, |
| 369 | const void *in, |
| 370 | void *out, |
| 371 | size_t len, |
| 372 | Error **errp); |
| 373 | |
| 374 | static int do_qcrypto_block_cipher_encdec(QCryptoCipher *cipher, |
| 375 | size_t niv, |
| 376 | QCryptoIVGen *ivgen, |
| 377 | QemuMutex *ivgen_mutex, |
| 378 | int sectorsize, |
| 379 | uint64_t offset, |
| 380 | uint8_t *buf, |
| 381 | size_t len, |
| 382 | QCryptoCipherEncDecFunc func, |
| 383 | Error **errp) |
| 384 | { |
| 385 | g_autofree uint8_t *iv = niv ? g_new0(uint8_t, niv) : NULL; |
| 386 | int ret = -1; |
| 387 | uint64_t startsector = offset / sectorsize; |
| 388 | |
| 389 | assert(QEMU_IS_ALIGNED(offset, sectorsize)); |
| 390 | assert(QEMU_IS_ALIGNED(len, sectorsize)); |
| 391 | |
| 392 | while (len > 0) { |
| 393 | size_t nbytes; |
| 394 | if (niv) { |
| 395 | if (ivgen_mutex) { |
| 396 | qemu_mutex_lock(ivgen_mutex); |
| 397 | } |
| 398 | ret = qcrypto_ivgen_calculate(ivgen, startsector, iv, niv, errp); |
| 399 | if (ivgen_mutex) { |
| 400 | qemu_mutex_unlock(ivgen_mutex); |
| 401 | } |
| 402 | |
| 403 | if (ret < 0) { |
| 404 | return -1; |
| 405 | } |
| 406 | |
| 407 | if (qcrypto_cipher_setiv(cipher, |
| 408 | iv, niv, |
| 409 | errp) < 0) { |
| 410 | return -1; |
| 411 | } |
| 412 | } |
| 413 | |
| 414 | nbytes = len > sectorsize ? sectorsize : len; |
| 415 | if (func(cipher, buf, buf, nbytes, errp) < 0) { |
| 416 | return -1; |
| 417 | } |
| 418 | |
| 419 | startsector++; |
| 420 | buf += nbytes; |
| 421 | len -= nbytes; |
| 422 | } |
| 423 | |
| 424 | return 0; |
| 425 | } |
| 426 | |
| 427 | |
| 428 | int qcrypto_block_cipher_decrypt_helper(QCryptoCipher *cipher, |
| 429 | size_t niv, |
| 430 | QCryptoIVGen *ivgen, |
| 431 | int sectorsize, |
| 432 | uint64_t offset, |
| 433 | uint8_t *buf, |
| 434 | size_t len, |
| 435 | Error **errp) |
| 436 | { |
| 437 | return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize, |
| 438 | offset, buf, len, |
| 439 | qcrypto_cipher_decrypt, errp); |
| 440 | } |
| 441 | |
| 442 | |
| 443 | int qcrypto_block_cipher_encrypt_helper(QCryptoCipher *cipher, |
| 444 | size_t niv, |
| 445 | QCryptoIVGen *ivgen, |
| 446 | int sectorsize, |
| 447 | uint64_t offset, |
| 448 | uint8_t *buf, |
| 449 | size_t len, |
| 450 | Error **errp) |
| 451 | { |
| 452 | return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize, |
| 453 | offset, buf, len, |
| 454 | qcrypto_cipher_encrypt, errp); |
| 455 | } |
| 456 | |
| 457 | int qcrypto_block_decrypt_helper(QCryptoBlock *block, |
| 458 | int sectorsize, |
| 459 | uint64_t offset, |
| 460 | uint8_t *buf, |
| 461 | size_t len, |
| 462 | Error **errp) |
| 463 | { |
| 464 | int ret; |
| 465 | QCryptoCipher *cipher = qcrypto_block_pop_cipher(block, errp); |
| 466 | if (!cipher) { |
| 467 | return -1; |
| 468 | } |
| 469 | |
| 470 | ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen, |
| 471 | &block->mutex, sectorsize, offset, buf, |
| 472 | len, qcrypto_cipher_decrypt, errp); |
| 473 | |
| 474 | qcrypto_block_push_cipher(block, cipher); |
| 475 | |
| 476 | return ret; |
| 477 | } |
| 478 | |
| 479 | int qcrypto_block_encrypt_helper(QCryptoBlock *block, |
| 480 | int sectorsize, |
| 481 | uint64_t offset, |
| 482 | uint8_t *buf, |
| 483 | size_t len, |
| 484 | Error **errp) |
| 485 | { |
| 486 | int ret; |
| 487 | QCryptoCipher *cipher = qcrypto_block_pop_cipher(block, errp); |
| 488 | if (!cipher) { |
| 489 | return -1; |
| 490 | } |
| 491 | |
| 492 | ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen, |
| 493 | &block->mutex, sectorsize, offset, buf, |
| 494 | len, qcrypto_cipher_encrypt, errp); |
| 495 | |
| 496 | qcrypto_block_push_cipher(block, cipher); |
| 497 | |
| 498 | return ret; |
| 499 | } |