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                                        1,
 233                                        errp);
 234
 235     if (!crypto->block) {
 236         ret = -EIO;
 237         goto cleanup;
 238     }
 239
 240     bs->encrypted = true;
 241
 242     ret = 0;
 243  cleanup:
 244     qobject_unref(cryptoopts);
 245     qapi_free_QCryptoBlockOpenOptions(open_opts);
 246     return ret;
 247 }
 248
 249
 250 static int block_crypto_co_create_generic(BlockDriverState *bs,
 251                                           int64_t size,
 252                                           QCryptoBlockCreateOptions *opts,
 253                                           Error **errp)
 254 {
 255     int ret;
 256     BlockBackend *blk;
 257     QCryptoBlock *crypto = NULL;
 258     struct BlockCryptoCreateData data;
 259
 260     blk = blk_new(bdrv_get_aio_context(bs),
 261                   BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
 262
 263     ret = blk_insert_bs(blk, bs, errp);
 264     if (ret < 0) {
 265         goto cleanup;
 266     }
 267
 268     data = (struct BlockCryptoCreateData) {
 269         .blk = blk,
 270         .size = size,
 271     };
 272
 273     crypto = qcrypto_block_create(opts, NULL,
 274                                   block_crypto_init_func,
 275                                   block_crypto_write_func,
 276                                   &data,
 277                                   errp);
 278
 279     if (!crypto) {
 280         ret = -EIO;
 281         goto cleanup;
 282     }
 283
 284     ret = 0;
 285  cleanup:
 286     qcrypto_block_free(crypto);
 287     blk_unref(blk);
 288     return ret;
 289 }
 290
 291 static int coroutine_fn
 292 block_crypto_co_truncate(BlockDriverState *bs, int64_t offset,
 293                          PreallocMode prealloc, Error **errp)
 294 {
 295     BlockCrypto *crypto = bs->opaque;
 296     uint64_t payload_offset =
 297         qcrypto_block_get_payload_offset(crypto->block);
 298
 299     if (payload_offset > INT64_MAX - offset) {
 300         error_setg(errp, "The requested file size is too large");
 301         return -EFBIG;
 302     }
 303
 304     offset += payload_offset;
 305
 306     return bdrv_co_truncate(bs->file, offset, prealloc, errp);
 307 }
 308
 309 static void block_crypto_close(BlockDriverState *bs)
 310 {
 311     BlockCrypto *crypto = bs->opaque;
 312     qcrypto_block_free(crypto->block);
 313 }
 314
 315 static int block_crypto_reopen_prepare(BDRVReopenState *state,
 316                                        BlockReopenQueue *queue, Error **errp)
 317 {
 318     /* nothing needs checking */
 319     return 0;
 320 }
 321
 322 /*
 323  * 1 MB bounce buffer gives good performance / memory tradeoff
 324  * when using cache=none|directsync.
 325  */
 326 #define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024)
 327
 328 static coroutine_fn int
 329 block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 330                        QEMUIOVector *qiov, int flags)
 331 {
 332     BlockCrypto *crypto = bs->opaque;
 333     uint64_t cur_bytes; /* number of bytes in current iteration */
 334     uint64_t bytes_done = 0;
 335     uint8_t *cipher_data = NULL;
 336     QEMUIOVector hd_qiov;
 337     int ret = 0;
 338     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 339     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 340
 341     assert(!flags);
 342     assert(payload_offset < INT64_MAX);
 343     assert(QEMU_IS_ALIGNED(offset, sector_size));
 344     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 345
 346     qemu_iovec_init(&hd_qiov, qiov->niov);
 347
 348     /* Bounce buffer because we don't wish to expose cipher text
 349      * in qiov which points to guest memory.
 350      */
 351     cipher_data =
 352         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 353                                               qiov->size));
 354     if (cipher_data == NULL) {
 355         ret = -ENOMEM;
 356         goto cleanup;
 357     }
 358
 359     while (bytes) {
 360         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 361
 362         qemu_iovec_reset(&hd_qiov);
 363         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 364
 365         ret = bdrv_co_preadv(bs->file, payload_offset + offset + bytes_done,
 366                              cur_bytes, &hd_qiov, 0);
 367         if (ret < 0) {
 368             goto cleanup;
 369         }
 370
 371         if (qcrypto_block_decrypt(crypto->block, offset + bytes_done,
 372                                   cipher_data, cur_bytes, NULL) < 0) {
 373             ret = -EIO;
 374             goto cleanup;
 375         }
 376
 377         qemu_iovec_from_buf(qiov, bytes_done, cipher_data, cur_bytes);
 378
 379         bytes -= cur_bytes;
 380         bytes_done += cur_bytes;
 381     }
 382
 383  cleanup:
 384     qemu_iovec_destroy(&hd_qiov);
 385     qemu_vfree(cipher_data);
 386
 387     return ret;
 388 }
 389
 390
 391 static coroutine_fn int
 392 block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 393                         QEMUIOVector *qiov, int flags)
 394 {
 395     BlockCrypto *crypto = bs->opaque;
 396     uint64_t cur_bytes; /* number of bytes in current iteration */
 397     uint64_t bytes_done = 0;
 398     uint8_t *cipher_data = NULL;
 399     QEMUIOVector hd_qiov;
 400     int ret = 0;
 401     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 402     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 403
 404     assert(!(flags & ~BDRV_REQ_FUA));
 405     assert(payload_offset < INT64_MAX);
 406     assert(QEMU_IS_ALIGNED(offset, sector_size));
 407     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 408
 409     qemu_iovec_init(&hd_qiov, qiov->niov);
 410
 411     /* Bounce buffer because we're not permitted to touch
 412      * contents of qiov - it points to guest memory.
 413      */
 414     cipher_data =
 415         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 416                                               qiov->size));
 417     if (cipher_data == NULL) {
 418         ret = -ENOMEM;
 419         goto cleanup;
 420     }
 421
 422     while (bytes) {
 423         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 424
 425         qemu_iovec_to_buf(qiov, bytes_done, cipher_data, cur_bytes);
 426
 427         if (qcrypto_block_encrypt(crypto->block, offset + bytes_done,
 428                                   cipher_data, cur_bytes, NULL) < 0) {
 429             ret = -EIO;
 430             goto cleanup;
 431         }
 432
 433         qemu_iovec_reset(&hd_qiov);
 434         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 435
 436         ret = bdrv_co_pwritev(bs->file, payload_offset + offset + bytes_done,
 437                               cur_bytes, &hd_qiov, flags);
 438         if (ret < 0) {
 439             goto cleanup;
 440         }
 441
 442         bytes -= cur_bytes;
 443         bytes_done += cur_bytes;
 444     }
 445
 446  cleanup:
 447     qemu_iovec_destroy(&hd_qiov);
 448     qemu_vfree(cipher_data);
 449
 450     return ret;
 451 }
 452
 453 static void block_crypto_refresh_limits(BlockDriverState *bs, Error **errp)
 454 {
 455     BlockCrypto *crypto = bs->opaque;
 456     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 457     bs->bl.request_alignment = sector_size; /* No sub-sector I/O */
 458 }
 459
 460
 461 static int64_t block_crypto_getlength(BlockDriverState *bs)
 462 {
 463     BlockCrypto *crypto = bs->opaque;
 464     int64_t len = bdrv_getlength(bs->file->bs);
 465
 466     uint64_t offset = qcrypto_block_get_payload_offset(crypto->block);
 467     assert(offset < INT64_MAX);
 468
 469     if (offset > len) {
 470         return -EIO;
 471     }
 472
 473     len -= offset;
 474
 475     return len;
 476 }
 477
 478
 479 static int block_crypto_probe_luks(const uint8_t *buf,
 480                                    int buf_size,
 481                                    const char *filename) {
 482     return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 483                                       buf, buf_size, filename);
 484 }
 485
 486 static int block_crypto_open_luks(BlockDriverState *bs,
 487                                   QDict *options,
 488                                   int flags,
 489                                   Error **errp)
 490 {
 491     return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 492                                      &block_crypto_runtime_opts_luks,
 493                                      bs, options, flags, errp);
 494 }
 495
 496 static int coroutine_fn
 497 block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
 498 {
 499     BlockdevCreateOptionsLUKS *luks_opts;
 500     BlockDriverState *bs = NULL;
 501     QCryptoBlockCreateOptions create_opts;
 502     int ret;
 503
 504     assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
 505     luks_opts = &create_options->u.luks;
 506
 507     bs = bdrv_open_blockdev_ref(luks_opts->file, errp);
 508     if (bs == NULL) {
 509         return -EIO;
 510     }
 511
 512     create_opts = (QCryptoBlockCreateOptions) {
 513         .format = Q_CRYPTO_BLOCK_FORMAT_LUKS,
 514         .u.luks = *qapi_BlockdevCreateOptionsLUKS_base(luks_opts),
 515     };
 516
 517     ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
 518                                          errp);
 519     if (ret < 0) {
 520         goto fail;
 521     }
 522
 523     ret = 0;
 524 fail:
 525     bdrv_unref(bs);
 526     return ret;
 527 }
 528
 529 static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
 530                                                          QemuOpts *opts,
 531                                                          Error **errp)
 532 {
 533     QCryptoBlockCreateOptions *create_opts = NULL;
 534     BlockDriverState *bs = NULL;
 535     QDict *cryptoopts;
 536     int64_t size;
 537     int ret;
 538
 539     /* Parse options */
 540     size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
 541
 542     cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
 543                                              &block_crypto_create_opts_luks,
 544                                              true);
 545
 546     qdict_put_str(cryptoopts, "format", "luks");
 547     create_opts = block_crypto_create_opts_init(cryptoopts, errp);
 548     if (!create_opts) {
 549         ret = -EINVAL;
 550         goto fail;
 551     }
 552
 553     /* Create protocol layer */
 554     ret = bdrv_create_file(filename, opts, errp);
 555     if (ret < 0) {
 556         goto fail;
 557     }
 558
 559     bs = bdrv_open(filename, NULL, NULL,
 560                    BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
 561     if (!bs) {
 562         ret = -EINVAL;
 563         goto fail;
 564     }
 565
 566     /* Create format layer */
 567     ret = block_crypto_co_create_generic(bs, size, create_opts, errp);
 568     if (ret < 0) {
 569         goto fail;
 570     }
 571
 572     ret = 0;
 573 fail:
 574     bdrv_unref(bs);
 575     qapi_free_QCryptoBlockCreateOptions(create_opts);
 576     qobject_unref(cryptoopts);
 577     return ret;
 578 }
 579
 580 static int block_crypto_get_info_luks(BlockDriverState *bs,
 581                                       BlockDriverInfo *bdi)
 582 {
 583     BlockDriverInfo subbdi;
 584     int ret;
 585
 586     ret = bdrv_get_info(bs->file->bs, &subbdi);
 587     if (ret != 0) {
 588         return ret;
 589     }
 590
 591     bdi->unallocated_blocks_are_zero = false;
 592     bdi->cluster_size = subbdi.cluster_size;
 593
 594     return 0;
 595 }
 596
 597 static ImageInfoSpecific *
 598 block_crypto_get_specific_info_luks(BlockDriverState *bs, Error **errp)
 599 {
 600     BlockCrypto *crypto = bs->opaque;
 601     ImageInfoSpecific *spec_info;
 602     QCryptoBlockInfo *info;
 603
 604     info = qcrypto_block_get_info(crypto->block, errp);
 605     if (!info) {
 606         return NULL;
 607     }
 608     assert(info->format == Q_CRYPTO_BLOCK_FORMAT_LUKS);
 609
 610     spec_info = g_new(ImageInfoSpecific, 1);
 611     spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
 612     spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
 613     *spec_info->u.luks.data = info->u.luks;
 614
 615     /* Blank out pointers we've just stolen to avoid double free */
 616     memset(&info->u.luks, 0, sizeof(info->u.luks));
 617
 618     qapi_free_QCryptoBlockInfo(info);
 619
 620     return spec_info;
 621 }
 622
 623 static const char *const block_crypto_strong_runtime_opts[] = {
 624     BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET,
 625
 626     NULL
 627 };
 628
 629 static BlockDriver bdrv_crypto_luks = {
 630     .format_name        = "luks",
 631     .instance_size      = sizeof(BlockCrypto),
 632     .bdrv_probe         = block_crypto_probe_luks,
 633     .bdrv_open          = block_crypto_open_luks,
 634     .bdrv_close         = block_crypto_close,
 635     /* This driver doesn't modify LUKS metadata except when creating image.
 636      * Allow share-rw=on as a special case. */
 637     .bdrv_child_perm    = bdrv_filter_default_perms,
 638     .bdrv_co_create     = block_crypto_co_create_luks,
 639     .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
 640     .bdrv_co_truncate   = block_crypto_co_truncate,
 641     .create_opts        = &block_crypto_create_opts_luks,
 642
 643     .bdrv_reopen_prepare = block_crypto_reopen_prepare,
 644     .bdrv_refresh_limits = block_crypto_refresh_limits,
 645     .bdrv_co_preadv     = block_crypto_co_preadv,
 646     .bdrv_co_pwritev    = block_crypto_co_pwritev,
 647     .bdrv_getlength     = block_crypto_getlength,
 648     .bdrv_get_info      = block_crypto_get_info_luks,
 649     .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
 650
 651     .strong_runtime_opts = block_crypto_strong_runtime_opts,
 652 };
 653
 654 static void block_crypto_init(void)
 655 {
 656     bdrv_register(&bdrv_crypto_luks);
 657 }
 658
 659 block_init(block_crypto_init);