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 "sysemu/block-backend.h"
  25 #include "crypto/block.h"
  26 #include "qapi/opts-visitor.h"
  27 #include "qapi/qapi-visit-crypto.h"
  28 #include "qapi/qmp/qdict.h"
  29 #include "qapi/qobject-input-visitor.h"
  30 #include "qapi/error.h"
  31 #include "qemu/option.h"
  32 #include "block/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     /* User provided size should reflect amount of space made
 106      * available to the guest, so we must take account of that
 107      * which will be used by the crypto header
 108      */
 109     return blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
 110                         errp);
 111 }
 112
 113
 114 static QemuOptsList block_crypto_runtime_opts_luks = {
 115     .name = "crypto",
 116     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_runtime_opts_luks.head),
 117     .desc = {
 118         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 119         { /* end of list */ }
 120     },
 121 };
 122
 123
 124 static QemuOptsList block_crypto_create_opts_luks = {
 125     .name = "crypto",
 126     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
 127     .desc = {
 128         {
 129             .name = BLOCK_OPT_SIZE,
 130             .type = QEMU_OPT_SIZE,
 131             .help = "Virtual disk size"
 132         },
 133         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 134         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG(""),
 135         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE(""),
 136         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG(""),
 137         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG(""),
 138         BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG(""),
 139         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(""),
 140         { /* end of list */ }
 141     },
 142 };
 143
 144
 145 QCryptoBlockOpenOptions *
 146 block_crypto_open_opts_init(QCryptoBlockFormat format,
 147                             QDict *opts,
 148                             Error **errp)
 149 {
 150     Visitor *v;
 151     QCryptoBlockOpenOptions *ret = NULL;
 152     Error *local_err = NULL;
 153
 154     ret = g_new0(QCryptoBlockOpenOptions, 1);
 155     ret->format = format;
 156
 157     v = qobject_input_visitor_new_keyval(QOBJECT(opts));
 158
 159     visit_start_struct(v, NULL, NULL, 0, &local_err);
 160     if (local_err) {
 161         goto out;
 162     }
 163
 164     switch (format) {
 165     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 166         visit_type_QCryptoBlockOptionsLUKS_members(
 167             v, &ret->u.luks, &local_err);
 168         break;
 169
 170     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
 171         visit_type_QCryptoBlockOptionsQCow_members(
 172             v, &ret->u.qcow, &local_err);
 173         break;
 174
 175     default:
 176         error_setg(&local_err, "Unsupported block format %d", format);
 177         break;
 178     }
 179     if (!local_err) {
 180         visit_check_struct(v, &local_err);
 181     }
 182
 183     visit_end_struct(v, NULL);
 184
 185  out:
 186     if (local_err) {
 187         error_propagate(errp, local_err);
 188         qapi_free_QCryptoBlockOpenOptions(ret);
 189         ret = NULL;
 190     }
 191     visit_free(v);
 192     return ret;
 193 }
 194
 195
 196 QCryptoBlockCreateOptions *
 197 block_crypto_create_opts_init(QCryptoBlockFormat format,
 198                               QDict *opts,
 199                               Error **errp)
 200 {
 201     Visitor *v;
 202     QCryptoBlockCreateOptions *ret = NULL;
 203     Error *local_err = NULL;
 204
 205     ret = g_new0(QCryptoBlockCreateOptions, 1);
 206     ret->format = format;
 207
 208     v = qobject_input_visitor_new_keyval(QOBJECT(opts));
 209
 210     visit_start_struct(v, NULL, NULL, 0, &local_err);
 211     if (local_err) {
 212         goto out;
 213     }
 214
 215     switch (format) {
 216     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 217         visit_type_QCryptoBlockCreateOptionsLUKS_members(
 218             v, &ret->u.luks, &local_err);
 219         break;
 220
 221     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
 222         visit_type_QCryptoBlockOptionsQCow_members(
 223             v, &ret->u.qcow, &local_err);
 224         break;
 225
 226     default:
 227         error_setg(&local_err, "Unsupported block format %d", format);
 228         break;
 229     }
 230     if (!local_err) {
 231         visit_check_struct(v, &local_err);
 232     }
 233
 234     visit_end_struct(v, NULL);
 235
 236  out:
 237     if (local_err) {
 238         error_propagate(errp, local_err);
 239         qapi_free_QCryptoBlockCreateOptions(ret);
 240         ret = NULL;
 241     }
 242     visit_free(v);
 243     return ret;
 244 }
 245
 246
 247 static int block_crypto_open_generic(QCryptoBlockFormat format,
 248                                      QemuOptsList *opts_spec,
 249                                      BlockDriverState *bs,
 250                                      QDict *options,
 251                                      int flags,
 252                                      Error **errp)
 253 {
 254     BlockCrypto *crypto = bs->opaque;
 255     QemuOpts *opts = NULL;
 256     Error *local_err = NULL;
 257     int ret = -EINVAL;
 258     QCryptoBlockOpenOptions *open_opts = NULL;
 259     unsigned int cflags = 0;
 260     QDict *cryptoopts = NULL;
 261
 262     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 263                                false, errp);
 264     if (!bs->file) {
 265         return -EINVAL;
 266     }
 267
 268     bs->supported_write_flags = BDRV_REQ_FUA &
 269         bs->file->bs->supported_write_flags;
 270
 271     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
 272     qemu_opts_absorb_qdict(opts, options, &local_err);
 273     if (local_err) {
 274         error_propagate(errp, local_err);
 275         goto cleanup;
 276     }
 277
 278     cryptoopts = qemu_opts_to_qdict(opts, NULL);
 279
 280     open_opts = block_crypto_open_opts_init(format, cryptoopts, errp);
 281     if (!open_opts) {
 282         goto cleanup;
 283     }
 284
 285     if (flags & BDRV_O_NO_IO) {
 286         cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 287     }
 288     crypto->block = qcrypto_block_open(open_opts, NULL,
 289                                        block_crypto_read_func,
 290                                        bs,
 291                                        cflags,
 292                                        errp);
 293
 294     if (!crypto->block) {
 295         ret = -EIO;
 296         goto cleanup;
 297     }
 298
 299     bs->encrypted = true;
 300
 301     ret = 0;
 302  cleanup:
 303     QDECREF(cryptoopts);
 304     qapi_free_QCryptoBlockOpenOptions(open_opts);
 305     return ret;
 306 }
 307
 308
 309 static int block_crypto_create_generic(QCryptoBlockFormat format,
 310                                        const char *filename,
 311                                        QemuOpts *opts,
 312                                        Error **errp)
 313 {
 314     int ret = -EINVAL;
 315     QCryptoBlockCreateOptions *create_opts = NULL;
 316     QCryptoBlock *crypto = NULL;
 317     struct BlockCryptoCreateData data = {
 318         .size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 319                          BDRV_SECTOR_SIZE),
 320     };
 321     QDict *cryptoopts;
 322
 323     /* Parse options */
 324     cryptoopts = qemu_opts_to_qdict(opts, NULL);
 325
 326     create_opts = block_crypto_create_opts_init(format, cryptoopts, errp);
 327     if (!create_opts) {
 328         return -1;
 329     }
 330
 331     /* Create protocol layer */
 332     ret = bdrv_create_file(filename, opts, errp);
 333     if (ret < 0) {
 334         return ret;
 335     }
 336
 337     data.blk = blk_new_open(filename, NULL, NULL,
 338                             BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL,
 339                             errp);
 340     if (!data.blk) {
 341         return -EINVAL;
 342     }
 343
 344     /* Create format layer */
 345     crypto = qcrypto_block_create(create_opts, NULL,
 346                                   block_crypto_init_func,
 347                                   block_crypto_write_func,
 348                                   &data,
 349                                   errp);
 350
 351     if (!crypto) {
 352         ret = -EIO;
 353         goto cleanup;
 354     }
 355
 356     ret = 0;
 357  cleanup:
 358     QDECREF(cryptoopts);
 359     qcrypto_block_free(crypto);
 360     blk_unref(data.blk);
 361     qapi_free_QCryptoBlockCreateOptions(create_opts);
 362     return ret;
 363 }
 364
 365 static int block_crypto_truncate(BlockDriverState *bs, int64_t offset,
 366                                  PreallocMode prealloc, Error **errp)
 367 {
 368     BlockCrypto *crypto = bs->opaque;
 369     uint64_t payload_offset =
 370         qcrypto_block_get_payload_offset(crypto->block);
 371     assert(payload_offset < (INT64_MAX - offset));
 372
 373     offset += payload_offset;
 374
 375     return bdrv_truncate(bs->file, offset, prealloc, errp);
 376 }
 377
 378 static void block_crypto_close(BlockDriverState *bs)
 379 {
 380     BlockCrypto *crypto = bs->opaque;
 381     qcrypto_block_free(crypto->block);
 382 }
 383
 384 static int block_crypto_reopen_prepare(BDRVReopenState *state,
 385                                        BlockReopenQueue *queue, Error **errp)
 386 {
 387     /* nothing needs checking */
 388     return 0;
 389 }
 390
 391 /*
 392  * 1 MB bounce buffer gives good performance / memory tradeoff
 393  * when using cache=none|directsync.
 394  */
 395 #define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024)
 396
 397 static coroutine_fn int
 398 block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 399                        QEMUIOVector *qiov, int flags)
 400 {
 401     BlockCrypto *crypto = bs->opaque;
 402     uint64_t cur_bytes; /* number of bytes in current iteration */
 403     uint64_t bytes_done = 0;
 404     uint8_t *cipher_data = NULL;
 405     QEMUIOVector hd_qiov;
 406     int ret = 0;
 407     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 408     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 409
 410     assert(!flags);
 411     assert(payload_offset < INT64_MAX);
 412     assert(QEMU_IS_ALIGNED(offset, sector_size));
 413     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 414
 415     qemu_iovec_init(&hd_qiov, qiov->niov);
 416
 417     /* Bounce buffer because we don't wish to expose cipher text
 418      * in qiov which points to guest memory.
 419      */
 420     cipher_data =
 421         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 422                                               qiov->size));
 423     if (cipher_data == NULL) {
 424         ret = -ENOMEM;
 425         goto cleanup;
 426     }
 427
 428     while (bytes) {
 429         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 430
 431         qemu_iovec_reset(&hd_qiov);
 432         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 433
 434         ret = bdrv_co_preadv(bs->file, payload_offset + offset + bytes_done,
 435                              cur_bytes, &hd_qiov, 0);
 436         if (ret < 0) {
 437             goto cleanup;
 438         }
 439
 440         if (qcrypto_block_decrypt(crypto->block, offset + bytes_done,
 441                                   cipher_data, cur_bytes, NULL) < 0) {
 442             ret = -EIO;
 443             goto cleanup;
 444         }
 445
 446         qemu_iovec_from_buf(qiov, bytes_done, cipher_data, cur_bytes);
 447
 448         bytes -= cur_bytes;
 449         bytes_done += cur_bytes;
 450     }
 451
 452  cleanup:
 453     qemu_iovec_destroy(&hd_qiov);
 454     qemu_vfree(cipher_data);
 455
 456     return ret;
 457 }
 458
 459
 460 static coroutine_fn int
 461 block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 462                         QEMUIOVector *qiov, int flags)
 463 {
 464     BlockCrypto *crypto = bs->opaque;
 465     uint64_t cur_bytes; /* number of bytes in current iteration */
 466     uint64_t bytes_done = 0;
 467     uint8_t *cipher_data = NULL;
 468     QEMUIOVector hd_qiov;
 469     int ret = 0;
 470     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 471     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 472
 473     assert(!(flags & ~BDRV_REQ_FUA));
 474     assert(payload_offset < INT64_MAX);
 475     assert(QEMU_IS_ALIGNED(offset, sector_size));
 476     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 477
 478     qemu_iovec_init(&hd_qiov, qiov->niov);
 479
 480     /* Bounce buffer because we're not permitted to touch
 481      * contents of qiov - it points to guest memory.
 482      */
 483     cipher_data =
 484         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 485                                               qiov->size));
 486     if (cipher_data == NULL) {
 487         ret = -ENOMEM;
 488         goto cleanup;
 489     }
 490
 491     while (bytes) {
 492         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 493
 494         qemu_iovec_to_buf(qiov, bytes_done, cipher_data, cur_bytes);
 495
 496         if (qcrypto_block_encrypt(crypto->block, offset + bytes_done,
 497                                   cipher_data, cur_bytes, NULL) < 0) {
 498             ret = -EIO;
 499             goto cleanup;
 500         }
 501
 502         qemu_iovec_reset(&hd_qiov);
 503         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 504
 505         ret = bdrv_co_pwritev(bs->file, payload_offset + offset + bytes_done,
 506                               cur_bytes, &hd_qiov, flags);
 507         if (ret < 0) {
 508             goto cleanup;
 509         }
 510
 511         bytes -= cur_bytes;
 512         bytes_done += cur_bytes;
 513     }
 514
 515  cleanup:
 516     qemu_iovec_destroy(&hd_qiov);
 517     qemu_vfree(cipher_data);
 518
 519     return ret;
 520 }
 521
 522 static void block_crypto_refresh_limits(BlockDriverState *bs, Error **errp)
 523 {
 524     BlockCrypto *crypto = bs->opaque;
 525     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 526     bs->bl.request_alignment = sector_size; /* No sub-sector I/O */
 527 }
 528
 529
 530 static int64_t block_crypto_getlength(BlockDriverState *bs)
 531 {
 532     BlockCrypto *crypto = bs->opaque;
 533     int64_t len = bdrv_getlength(bs->file->bs);
 534
 535     uint64_t offset = qcrypto_block_get_payload_offset(crypto->block);
 536     assert(offset < INT64_MAX);
 537     assert(offset < len);
 538
 539     len -= offset;
 540
 541     return len;
 542 }
 543
 544
 545 static int block_crypto_probe_luks(const uint8_t *buf,
 546                                    int buf_size,
 547                                    const char *filename) {
 548     return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 549                                       buf, buf_size, filename);
 550 }
 551
 552 static int block_crypto_open_luks(BlockDriverState *bs,
 553                                   QDict *options,
 554                                   int flags,
 555                                   Error **errp)
 556 {
 557     return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 558                                      &block_crypto_runtime_opts_luks,
 559                                      bs, options, flags, errp);
 560 }
 561
 562 static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
 563                                                          QemuOpts *opts,
 564                                                          Error **errp)
 565 {
 566     return block_crypto_create_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 567                                        filename, opts, errp);
 568 }
 569
 570 static int block_crypto_get_info_luks(BlockDriverState *bs,
 571                                       BlockDriverInfo *bdi)
 572 {
 573     BlockDriverInfo subbdi;
 574     int ret;
 575
 576     ret = bdrv_get_info(bs->file->bs, &subbdi);
 577     if (ret != 0) {
 578         return ret;
 579     }
 580
 581     bdi->unallocated_blocks_are_zero = false;
 582     bdi->cluster_size = subbdi.cluster_size;
 583
 584     return 0;
 585 }
 586
 587 static ImageInfoSpecific *
 588 block_crypto_get_specific_info_luks(BlockDriverState *bs)
 589 {
 590     BlockCrypto *crypto = bs->opaque;
 591     ImageInfoSpecific *spec_info;
 592     QCryptoBlockInfo *info;
 593
 594     info = qcrypto_block_get_info(crypto->block, NULL);
 595     if (!info) {
 596         return NULL;
 597     }
 598     if (info->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
 599         qapi_free_QCryptoBlockInfo(info);
 600         return NULL;
 601     }
 602
 603     spec_info = g_new(ImageInfoSpecific, 1);
 604     spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
 605     spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
 606     *spec_info->u.luks.data = info->u.luks;
 607
 608     /* Blank out pointers we've just stolen to avoid double free */
 609     memset(&info->u.luks, 0, sizeof(info->u.luks));
 610
 611     qapi_free_QCryptoBlockInfo(info);
 612
 613     return spec_info;
 614 }
 615
 616 BlockDriver bdrv_crypto_luks = {
 617     .format_name        = "luks",
 618     .instance_size      = sizeof(BlockCrypto),
 619     .bdrv_probe         = block_crypto_probe_luks,
 620     .bdrv_open          = block_crypto_open_luks,
 621     .bdrv_close         = block_crypto_close,
 622     .bdrv_child_perm    = bdrv_format_default_perms,
 623     .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
 624     .bdrv_truncate      = block_crypto_truncate,
 625     .create_opts        = &block_crypto_create_opts_luks,
 626
 627     .bdrv_reopen_prepare = block_crypto_reopen_prepare,
 628     .bdrv_refresh_limits = block_crypto_refresh_limits,
 629     .bdrv_co_preadv     = block_crypto_co_preadv,
 630     .bdrv_co_pwritev    = block_crypto_co_pwritev,
 631     .bdrv_getlength     = block_crypto_getlength,
 632     .bdrv_get_info      = block_crypto_get_info_luks,
 633     .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
 634 };
 635
 636 static void block_crypto_init(void)
 637 {
 638     bdrv_register(&bdrv_crypto_luks);
 639 }
 640
 641 block_init(block_crypto_init);