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