block/crypto.c

   1 /*
   2  * QEMU block full disk 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 #include "qemu/osdep.h"
  22
  23 #include "block/block_int.h"
  24 #include "block/qdict.h"
  25 #include "sysemu/block-backend.h"
  26 #include "crypto/block.h"
  27 #include "qapi/opts-visitor.h"
  28 #include "qapi/qapi-visit-crypto.h"
  29 #include "qapi/qobject-input-visitor.h"
  30 #include "qapi/error.h"
  31 #include "qemu/option.h"
  32 #include "crypto.h"
  33
  34 typedef struct BlockCrypto BlockCrypto;
  35
  36 struct BlockCrypto {
  37     QCryptoBlock *block;
  38 };
  39
  40
  41 static int block_crypto_probe_generic(QCryptoBlockFormat format,
  42                                       const uint8_t *buf,
  43                                       int buf_size,
  44                                       const char *filename)
  45 {
  46     if (qcrypto_block_has_format(format, buf, buf_size)) {
  47         return 100;
  48     } else {
  49         return 0;
  50     }
  51 }
  52
  53
  54 static ssize_t block_crypto_read_func(QCryptoBlock *block,
  55                                       size_t offset,
  56                                       uint8_t *buf,
  57                                       size_t buflen,
  58                                       void *opaque,
  59                                       Error **errp)
  60 {
  61     BlockDriverState *bs = opaque;
  62     ssize_t ret;
  63
  64     ret = bdrv_pread(bs->file, offset, buf, buflen);
  65     if (ret < 0) {
  66         error_setg_errno(errp, -ret, "Could not read encryption header");
  67         return ret;
  68     }
  69     return ret;
  70 }
  71
  72
  73 struct BlockCryptoCreateData {
  74     BlockBackend *blk;
  75     uint64_t size;
  76 };
  77
  78
  79 static ssize_t block_crypto_write_func(QCryptoBlock *block,
  80                                        size_t offset,
  81                                        const uint8_t *buf,
  82                                        size_t buflen,
  83                                        void *opaque,
  84                                        Error **errp)
  85 {
  86     struct BlockCryptoCreateData *data = opaque;
  87     ssize_t ret;
  88
  89     ret = blk_pwrite(data->blk, offset, buf, buflen, 0);
  90     if (ret < 0) {
  91         error_setg_errno(errp, -ret, "Could not write encryption header");
  92         return ret;
  93     }
  94     return ret;
  95 }
  96
  97
  98 static ssize_t block_crypto_init_func(QCryptoBlock *block,
  99                                       size_t headerlen,
 100                                       void *opaque,
 101                                       Error **errp)
 102 {
 103     struct BlockCryptoCreateData *data = opaque;
 104
 105     if (data->size > INT64_MAX || headerlen > INT64_MAX - data->size) {
 106         error_setg(errp, "The requested file size is too large");
 107         return -EFBIG;
 108     }
 109
 110     /* User provided size should reflect amount of space made
 111      * available to the guest, so we must take account of that
 112      * which will be used by the crypto header
 113      */
 114     return blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
 115                         errp);
 116 }
 117
 118
 119 static QemuOptsList block_crypto_runtime_opts_luks = {
 120     .name = "crypto",
 121     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_runtime_opts_luks.head),
 122     .desc = {
 123         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 124         { /* end of list */ }
 125     },
 126 };
 127
 128
 129 static QemuOptsList block_crypto_create_opts_luks = {
 130     .name = "crypto",
 131     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
 132     .desc = {
 133         {
 134             .name = BLOCK_OPT_SIZE,
 135             .type = QEMU_OPT_SIZE,
 136             .help = "Virtual disk size"
 137         },
 138         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 139         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG(""),
 140         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE(""),
 141         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG(""),
 142         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG(""),
 143         BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG(""),
 144         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(""),
 145         { /* end of list */ }
 146     },
 147 };
 148
 149
 150 QCryptoBlockOpenOptions *
 151 block_crypto_open_opts_init(QDict *opts, Error **errp)
 152 {
 153     Visitor *v;
 154     QCryptoBlockOpenOptions *ret;
 155
 156     v = qobject_input_visitor_new_flat_confused(opts, errp);
 157     if (!v) {
 158         return NULL;
 159     }
 160
 161     visit_type_QCryptoBlockOpenOptions(v, NULL, &ret, errp);
 162
 163     visit_free(v);
 164     return ret;
 165 }
 166
 167
 168 QCryptoBlockCreateOptions *
 169 block_crypto_create_opts_init(QDict *opts, Error **errp)
 170 {
 171     Visitor *v;
 172     QCryptoBlockCreateOptions *ret;
 173
 174     v = qobject_input_visitor_new_flat_confused(opts, errp);
 175     if (!v) {
 176         return NULL;
 177     }
 178
 179     visit_type_QCryptoBlockCreateOptions(v, NULL, &ret, errp);
 180
 181     visit_free(v);
 182     return ret;
 183 }
 184
 185
 186 static int block_crypto_open_generic(QCryptoBlockFormat format,
 187                                      QemuOptsList *opts_spec,
 188                                      BlockDriverState *bs,
 189                                      QDict *options,
 190                                      int flags,
 191                                      Error **errp)
 192 {
 193     BlockCrypto *crypto = bs->opaque;
 194     QemuOpts *opts = NULL;
 195     Error *local_err = NULL;
 196     int ret = -EINVAL;
 197     QCryptoBlockOpenOptions *open_opts = NULL;
 198     unsigned int cflags = 0;
 199     QDict *cryptoopts = NULL;
 200
 201     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 202                                false, errp);
 203     if (!bs->file) {
 204         return -EINVAL;
 205     }
 206
 207     bs->supported_write_flags = BDRV_REQ_FUA &
 208         bs->file->bs->supported_write_flags;
 209
 210     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
 211     qemu_opts_absorb_qdict(opts, options, &local_err);
 212     if (local_err) {
 213         error_propagate(errp, local_err);
 214         goto cleanup;
 215     }
 216
 217     cryptoopts = qemu_opts_to_qdict(opts, NULL);
 218     qdict_put_str(cryptoopts, "format", QCryptoBlockFormat_str(format));
 219
 220     open_opts = block_crypto_open_opts_init(cryptoopts, errp);
 221     if (!open_opts) {
 222         goto cleanup;
 223     }
 224
 225     if (flags & BDRV_O_NO_IO) {
 226         cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 227     }
 228     crypto->block = qcrypto_block_open(open_opts, NULL,
 229                                        block_crypto_read_func,
 230                                        bs,
 231                                        cflags,
 232                                        errp);
 233
 234     if (!crypto->block) {
 235         ret = -EIO;
 236         goto cleanup;
 237     }
 238
 239     bs->encrypted = true;
 240
 241     ret = 0;
 242  cleanup:
 243     qobject_unref(cryptoopts);
 244     qapi_free_QCryptoBlockOpenOptions(open_opts);
 245     return ret;
 246 }
 247
 248
 249 static int block_crypto_co_create_generic(BlockDriverState *bs,
 250                                           int64_t size,
 251                                           QCryptoBlockCreateOptions *opts,
 252                                           Error **errp)
 253 {
 254     int ret;
 255     BlockBackend *blk;
 256     QCryptoBlock *crypto = NULL;
 257     struct BlockCryptoCreateData data;
 258
 259     blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
 260
 261     ret = blk_insert_bs(blk, bs, errp);
 262     if (ret < 0) {
 263         goto cleanup;
 264     }
 265
 266     data = (struct BlockCryptoCreateData) {
 267         .blk = blk,
 268         .size = size,
 269     };
 270
 271     crypto = qcrypto_block_create(opts, NULL,
 272                                   block_crypto_init_func,
 273                                   block_crypto_write_func,
 274                                   &data,
 275                                   errp);
 276
 277     if (!crypto) {
 278         ret = -EIO;
 279         goto cleanup;
 280     }
 281
 282     ret = 0;
 283  cleanup:
 284     qcrypto_block_free(crypto);
 285     blk_unref(blk);
 286     return ret;
 287 }
 288
 289 static int coroutine_fn
 290 block_crypto_co_truncate(BlockDriverState *bs, int64_t offset,
 291                          PreallocMode prealloc, Error **errp)
 292 {
 293     BlockCrypto *crypto = bs->opaque;
 294     uint64_t payload_offset =
 295         qcrypto_block_get_payload_offset(crypto->block);
 296
 297     if (payload_offset > INT64_MAX - offset) {
 298         error_setg(errp, "The requested file size is too large");
 299         return -EFBIG;
 300     }
 301
 302     offset += payload_offset;
 303
 304     return bdrv_co_truncate(bs->file, offset, prealloc, errp);
 305 }
 306
 307 static void block_crypto_close(BlockDriverState *bs)
 308 {
 309     BlockCrypto *crypto = bs->opaque;
 310     qcrypto_block_free(crypto->block);
 311 }
 312
 313 static int block_crypto_reopen_prepare(BDRVReopenState *state,
 314                                        BlockReopenQueue *queue, Error **errp)
 315 {
 316     /* nothing needs checking */
 317     return 0;
 318 }
 319
 320 /*
 321  * 1 MB bounce buffer gives good performance / memory tradeoff
 322  * when using cache=none|directsync.
 323  */
 324 #define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024)
 325
 326 static coroutine_fn int
 327 block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 328                        QEMUIOVector *qiov, int flags)
 329 {
 330     BlockCrypto *crypto = bs->opaque;
 331     uint64_t cur_bytes; /* number of bytes in current iteration */
 332     uint64_t bytes_done = 0;
 333     uint8_t *cipher_data = NULL;
 334     QEMUIOVector hd_qiov;
 335     int ret = 0;
 336     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 337     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 338
 339     assert(!flags);
 340     assert(payload_offset < INT64_MAX);
 341     assert(QEMU_IS_ALIGNED(offset, sector_size));
 342     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 343
 344     qemu_iovec_init(&hd_qiov, qiov->niov);
 345
 346     /* Bounce buffer because we don't wish to expose cipher text
 347      * in qiov which points to guest memory.
 348      */
 349     cipher_data =
 350         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 351                                               qiov->size));
 352     if (cipher_data == NULL) {
 353         ret = -ENOMEM;
 354         goto cleanup;
 355     }
 356
 357     while (bytes) {
 358         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 359
 360         qemu_iovec_reset(&hd_qiov);
 361         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 362
 363         ret = bdrv_co_preadv(bs->file, payload_offset + offset + bytes_done,
 364                              cur_bytes, &hd_qiov, 0);
 365         if (ret < 0) {
 366             goto cleanup;
 367         }
 368
 369         if (qcrypto_block_decrypt(crypto->block, offset + bytes_done,
 370                                   cipher_data, cur_bytes, NULL) < 0) {
 371             ret = -EIO;
 372             goto cleanup;
 373         }
 374
 375         qemu_iovec_from_buf(qiov, bytes_done, cipher_data, cur_bytes);
 376
 377         bytes -= cur_bytes;
 378         bytes_done += cur_bytes;
 379     }
 380
 381  cleanup:
 382     qemu_iovec_destroy(&hd_qiov);
 383     qemu_vfree(cipher_data);
 384
 385     return ret;
 386 }
 387
 388
 389 static coroutine_fn int
 390 block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 391                         QEMUIOVector *qiov, int flags)
 392 {
 393     BlockCrypto *crypto = bs->opaque;
 394     uint64_t cur_bytes; /* number of bytes in current iteration */
 395     uint64_t bytes_done = 0;
 396     uint8_t *cipher_data = NULL;
 397     QEMUIOVector hd_qiov;
 398     int ret = 0;
 399     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 400     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 401
 402     assert(!(flags & ~BDRV_REQ_FUA));
 403     assert(payload_offset < INT64_MAX);
 404     assert(QEMU_IS_ALIGNED(offset, sector_size));
 405     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 406
 407     qemu_iovec_init(&hd_qiov, qiov->niov);
 408
 409     /* Bounce buffer because we're not permitted to touch
 410      * contents of qiov - it points to guest memory.
 411      */
 412     cipher_data =
 413         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 414                                               qiov->size));
 415     if (cipher_data == NULL) {
 416         ret = -ENOMEM;
 417         goto cleanup;
 418     }
 419
 420     while (bytes) {
 421         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 422
 423         qemu_iovec_to_buf(qiov, bytes_done, cipher_data, cur_bytes);
 424
 425         if (qcrypto_block_encrypt(crypto->block, offset + bytes_done,
 426                                   cipher_data, cur_bytes, NULL) < 0) {
 427             ret = -EIO;
 428             goto cleanup;
 429         }
 430
 431         qemu_iovec_reset(&hd_qiov);
 432         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 433
 434         ret = bdrv_co_pwritev(bs->file, payload_offset + offset + bytes_done,
 435                               cur_bytes, &hd_qiov, flags);
 436         if (ret < 0) {
 437             goto cleanup;
 438         }
 439
 440         bytes -= cur_bytes;
 441         bytes_done += cur_bytes;
 442     }
 443
 444  cleanup:
 445     qemu_iovec_destroy(&hd_qiov);
 446     qemu_vfree(cipher_data);
 447
 448     return ret;
 449 }
 450
 451 static void block_crypto_refresh_limits(BlockDriverState *bs, Error **errp)
 452 {
 453     BlockCrypto *crypto = bs->opaque;
 454     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 455     bs->bl.request_alignment = sector_size; /* No sub-sector I/O */
 456 }
 457
 458
 459 static int64_t block_crypto_getlength(BlockDriverState *bs)
 460 {
 461     BlockCrypto *crypto = bs->opaque;
 462     int64_t len = bdrv_getlength(bs->file->bs);
 463
 464     uint64_t offset = qcrypto_block_get_payload_offset(crypto->block);
 465     assert(offset < INT64_MAX);
 466
 467     if (offset > len) {
 468         return -EIO;
 469     }
 470
 471     len -= offset;
 472
 473     return len;
 474 }
 475
 476
 477 static int block_crypto_probe_luks(const uint8_t *buf,
 478                                    int buf_size,
 479                                    const char *filename) {
 480     return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 481                                       buf, buf_size, filename);
 482 }
 483
 484 static int block_crypto_open_luks(BlockDriverState *bs,
 485                                   QDict *options,
 486                                   int flags,
 487                                   Error **errp)
 488 {
 489     return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 490                                      &block_crypto_runtime_opts_luks,
 491                                      bs, options, flags, errp);
 492 }
 493
 494 static int coroutine_fn
 495 block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
 496 {
 497     BlockdevCreateOptionsLUKS *luks_opts;
 498     BlockDriverState *bs = NULL;
 499     QCryptoBlockCreateOptions create_opts;
 500     int ret;
 501
 502     assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
 503     luks_opts = &create_options->u.luks;
 504
 505     bs = bdrv_open_blockdev_ref(luks_opts->file, errp);
 506     if (bs == NULL) {
 507         return -EIO;
 508     }
 509
 510     create_opts = (QCryptoBlockCreateOptions) {
 511         .format = Q_CRYPTO_BLOCK_FORMAT_LUKS,
 512         .u.luks = *qapi_BlockdevCreateOptionsLUKS_base(luks_opts),
 513     };
 514
 515     ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
 516                                          errp);
 517     if (ret < 0) {
 518         goto fail;
 519     }
 520
 521     ret = 0;
 522 fail:
 523     bdrv_unref(bs);
 524     return ret;
 525 }
 526
 527 static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
 528                                                          QemuOpts *opts,
 529                                                          Error **errp)
 530 {
 531     QCryptoBlockCreateOptions *create_opts = NULL;
 532     BlockDriverState *bs = NULL;
 533     QDict *cryptoopts;
 534     int64_t size;
 535     int ret;
 536
 537     /* Parse options */
 538     size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
 539
 540     cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
 541                                              &block_crypto_create_opts_luks,
 542                                              true);
 543
 544     qdict_put_str(cryptoopts, "format", "luks");
 545     create_opts = block_crypto_create_opts_init(cryptoopts, errp);
 546     if (!create_opts) {
 547         ret = -EINVAL;
 548         goto fail;
 549     }
 550
 551     /* Create protocol layer */
 552     ret = bdrv_create_file(filename, opts, errp);
 553     if (ret < 0) {
 554         goto fail;
 555     }
 556
 557     bs = bdrv_open(filename, NULL, NULL,
 558                    BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
 559     if (!bs) {
 560         ret = -EINVAL;
 561         goto fail;
 562     }
 563
 564     /* Create format layer */
 565     ret = block_crypto_co_create_generic(bs, size, create_opts, errp);
 566     if (ret < 0) {
 567         goto fail;
 568     }
 569
 570     ret = 0;
 571 fail:
 572     bdrv_unref(bs);
 573     qapi_free_QCryptoBlockCreateOptions(create_opts);
 574     qobject_unref(cryptoopts);
 575     return ret;
 576 }
 577
 578 static int block_crypto_get_info_luks(BlockDriverState *bs,
 579                                       BlockDriverInfo *bdi)
 580 {
 581     BlockDriverInfo subbdi;
 582     int ret;
 583
 584     ret = bdrv_get_info(bs->file->bs, &subbdi);
 585     if (ret != 0) {
 586         return ret;
 587     }
 588
 589     bdi->unallocated_blocks_are_zero = false;
 590     bdi->cluster_size = subbdi.cluster_size;
 591
 592     return 0;
 593 }
 594
 595 static ImageInfoSpecific *
 596 block_crypto_get_specific_info_luks(BlockDriverState *bs)
 597 {
 598     BlockCrypto *crypto = bs->opaque;
 599     ImageInfoSpecific *spec_info;
 600     QCryptoBlockInfo *info;
 601
 602     info = qcrypto_block_get_info(crypto->block, NULL);
 603     if (!info) {
 604         return NULL;
 605     }
 606     if (info->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
 607         qapi_free_QCryptoBlockInfo(info);
 608         return NULL;
 609     }
 610
 611     spec_info = g_new(ImageInfoSpecific, 1);
 612     spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
 613     spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
 614     *spec_info->u.luks.data = info->u.luks;
 615
 616     /* Blank out pointers we've just stolen to avoid double free */
 617     memset(&info->u.luks, 0, sizeof(info->u.luks));
 618
 619     qapi_free_QCryptoBlockInfo(info);
 620
 621     return spec_info;
 622 }
 623
 624 BlockDriver bdrv_crypto_luks = {
 625     .format_name        = "luks",
 626     .instance_size      = sizeof(BlockCrypto),
 627     .bdrv_probe         = block_crypto_probe_luks,
 628     .bdrv_open          = block_crypto_open_luks,
 629     .bdrv_close         = block_crypto_close,
 630     /* This driver doesn't modify LUKS metadata except when creating image.
 631      * Allow share-rw=on as a special case. */
 632     .bdrv_child_perm    = bdrv_filter_default_perms,
 633     .bdrv_co_create     = block_crypto_co_create_luks,
 634     .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
 635     .bdrv_co_truncate   = block_crypto_co_truncate,
 636     .create_opts        = &block_crypto_create_opts_luks,
 637
 638     .bdrv_reopen_prepare = block_crypto_reopen_prepare,
 639     .bdrv_refresh_limits = block_crypto_refresh_limits,
 640     .bdrv_co_preadv     = block_crypto_co_preadv,
 641     .bdrv_co_pwritev    = block_crypto_co_pwritev,
 642     .bdrv_getlength     = block_crypto_getlength,
 643     .bdrv_get_info      = block_crypto_get_info_luks,
 644     .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
 645 };
 646
 647 static void block_crypto_init(void)
 648 {
 649     bdrv_register(&bdrv_crypto_luks);
 650 }
 651
 652 block_init(block_crypto_init);