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/qmp/qdict.h"
  28 #include "qapi/qobject-input-visitor.h"
  29 #include "qapi-visit.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     const char *filename;
  75     QemuOpts *opts;
  76     BlockBackend *blk;
  77     uint64_t size;
  78 };
  79
  80
  81 static ssize_t block_crypto_write_func(QCryptoBlock *block,
  82                                        size_t offset,
  83                                        const uint8_t *buf,
  84                                        size_t buflen,
  85                                        void *opaque,
  86                                        Error **errp)
  87 {
  88     struct BlockCryptoCreateData *data = opaque;
  89     ssize_t ret;
  90
  91     ret = blk_pwrite(data->blk, offset, buf, buflen, 0);
  92     if (ret < 0) {
  93         error_setg_errno(errp, -ret, "Could not write encryption header");
  94         return ret;
  95     }
  96     return ret;
  97 }
  98
  99
 100 static ssize_t block_crypto_init_func(QCryptoBlock *block,
 101                                       size_t headerlen,
 102                                       void *opaque,
 103                                       Error **errp)
 104 {
 105     struct BlockCryptoCreateData *data = opaque;
 106     int ret;
 107
 108     /* User provided size should reflect amount of space made
 109      * available to the guest, so we must take account of that
 110      * which will be used by the crypto header
 111      */
 112     data->size += headerlen;
 113
 114     qemu_opt_set_number(data->opts, BLOCK_OPT_SIZE, data->size, &error_abort);
 115     ret = bdrv_create_file(data->filename, data->opts, errp);
 116     if (ret < 0) {
 117         return -1;
 118     }
 119
 120     data->blk = blk_new_open(data->filename, NULL, NULL,
 121                              BDRV_O_RDWR | BDRV_O_PROTOCOL, errp);
 122     if (!data->blk) {
 123         return -1;
 124     }
 125
 126     return 0;
 127 }
 128
 129
 130 static QemuOptsList block_crypto_runtime_opts_luks = {
 131     .name = "crypto",
 132     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_runtime_opts_luks.head),
 133     .desc = {
 134         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 135         { /* end of list */ }
 136     },
 137 };
 138
 139
 140 static QemuOptsList block_crypto_create_opts_luks = {
 141     .name = "crypto",
 142     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
 143     .desc = {
 144         {
 145             .name = BLOCK_OPT_SIZE,
 146             .type = QEMU_OPT_SIZE,
 147             .help = "Virtual disk size"
 148         },
 149         BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
 150         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG(""),
 151         BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE(""),
 152         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG(""),
 153         BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG(""),
 154         BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG(""),
 155         BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(""),
 156         { /* end of list */ }
 157     },
 158 };
 159
 160
 161 QCryptoBlockOpenOptions *
 162 block_crypto_open_opts_init(QCryptoBlockFormat format,
 163                             QDict *opts,
 164                             Error **errp)
 165 {
 166     Visitor *v;
 167     QCryptoBlockOpenOptions *ret = NULL;
 168     Error *local_err = NULL;
 169
 170     ret = g_new0(QCryptoBlockOpenOptions, 1);
 171     ret->format = format;
 172
 173     v = qobject_input_visitor_new_keyval(QOBJECT(opts));
 174
 175     visit_start_struct(v, NULL, NULL, 0, &local_err);
 176     if (local_err) {
 177         goto out;
 178     }
 179
 180     switch (format) {
 181     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 182         visit_type_QCryptoBlockOptionsLUKS_members(
 183             v, &ret->u.luks, &local_err);
 184         break;
 185
 186     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
 187         visit_type_QCryptoBlockOptionsQCow_members(
 188             v, &ret->u.qcow, &local_err);
 189         break;
 190
 191     default:
 192         error_setg(&local_err, "Unsupported block format %d", format);
 193         break;
 194     }
 195     if (!local_err) {
 196         visit_check_struct(v, &local_err);
 197     }
 198
 199     visit_end_struct(v, NULL);
 200
 201  out:
 202     if (local_err) {
 203         error_propagate(errp, local_err);
 204         qapi_free_QCryptoBlockOpenOptions(ret);
 205         ret = NULL;
 206     }
 207     visit_free(v);
 208     return ret;
 209 }
 210
 211
 212 QCryptoBlockCreateOptions *
 213 block_crypto_create_opts_init(QCryptoBlockFormat format,
 214                               QDict *opts,
 215                               Error **errp)
 216 {
 217     Visitor *v;
 218     QCryptoBlockCreateOptions *ret = NULL;
 219     Error *local_err = NULL;
 220
 221     ret = g_new0(QCryptoBlockCreateOptions, 1);
 222     ret->format = format;
 223
 224     v = qobject_input_visitor_new_keyval(QOBJECT(opts));
 225
 226     visit_start_struct(v, NULL, NULL, 0, &local_err);
 227     if (local_err) {
 228         goto out;
 229     }
 230
 231     switch (format) {
 232     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 233         visit_type_QCryptoBlockCreateOptionsLUKS_members(
 234             v, &ret->u.luks, &local_err);
 235         break;
 236
 237     case Q_CRYPTO_BLOCK_FORMAT_QCOW:
 238         visit_type_QCryptoBlockOptionsQCow_members(
 239             v, &ret->u.qcow, &local_err);
 240         break;
 241
 242     default:
 243         error_setg(&local_err, "Unsupported block format %d", format);
 244         break;
 245     }
 246     if (!local_err) {
 247         visit_check_struct(v, &local_err);
 248     }
 249
 250     visit_end_struct(v, NULL);
 251
 252  out:
 253     if (local_err) {
 254         error_propagate(errp, local_err);
 255         qapi_free_QCryptoBlockCreateOptions(ret);
 256         ret = NULL;
 257     }
 258     visit_free(v);
 259     return ret;
 260 }
 261
 262
 263 static int block_crypto_open_generic(QCryptoBlockFormat format,
 264                                      QemuOptsList *opts_spec,
 265                                      BlockDriverState *bs,
 266                                      QDict *options,
 267                                      int flags,
 268                                      Error **errp)
 269 {
 270     BlockCrypto *crypto = bs->opaque;
 271     QemuOpts *opts = NULL;
 272     Error *local_err = NULL;
 273     int ret = -EINVAL;
 274     QCryptoBlockOpenOptions *open_opts = NULL;
 275     unsigned int cflags = 0;
 276     QDict *cryptoopts = NULL;
 277
 278     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
 279                                false, errp);
 280     if (!bs->file) {
 281         return -EINVAL;
 282     }
 283
 284     bs->supported_write_flags = BDRV_REQ_FUA &
 285         bs->file->bs->supported_write_flags;
 286
 287     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
 288     qemu_opts_absorb_qdict(opts, options, &local_err);
 289     if (local_err) {
 290         error_propagate(errp, local_err);
 291         goto cleanup;
 292     }
 293
 294     cryptoopts = qemu_opts_to_qdict(opts, NULL);
 295
 296     open_opts = block_crypto_open_opts_init(format, cryptoopts, errp);
 297     if (!open_opts) {
 298         goto cleanup;
 299     }
 300
 301     if (flags & BDRV_O_NO_IO) {
 302         cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 303     }
 304     crypto->block = qcrypto_block_open(open_opts, NULL,
 305                                        block_crypto_read_func,
 306                                        bs,
 307                                        cflags,
 308                                        errp);
 309
 310     if (!crypto->block) {
 311         ret = -EIO;
 312         goto cleanup;
 313     }
 314
 315     bs->encrypted = true;
 316
 317     ret = 0;
 318  cleanup:
 319     QDECREF(cryptoopts);
 320     qapi_free_QCryptoBlockOpenOptions(open_opts);
 321     return ret;
 322 }
 323
 324
 325 static int block_crypto_create_generic(QCryptoBlockFormat format,
 326                                        const char *filename,
 327                                        QemuOpts *opts,
 328                                        Error **errp)
 329 {
 330     int ret = -EINVAL;
 331     QCryptoBlockCreateOptions *create_opts = NULL;
 332     QCryptoBlock *crypto = NULL;
 333     struct BlockCryptoCreateData data = {
 334         .size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 335                          BDRV_SECTOR_SIZE),
 336         .opts = opts,
 337         .filename = filename,
 338     };
 339     QDict *cryptoopts;
 340
 341     cryptoopts = qemu_opts_to_qdict(opts, NULL);
 342
 343     create_opts = block_crypto_create_opts_init(format, cryptoopts, errp);
 344     if (!create_opts) {
 345         return -1;
 346     }
 347
 348     crypto = qcrypto_block_create(create_opts, NULL,
 349                                   block_crypto_init_func,
 350                                   block_crypto_write_func,
 351                                   &data,
 352                                   errp);
 353
 354     if (!crypto) {
 355         ret = -EIO;
 356         goto cleanup;
 357     }
 358
 359     ret = 0;
 360  cleanup:
 361     QDECREF(cryptoopts);
 362     qcrypto_block_free(crypto);
 363     blk_unref(data.blk);
 364     qapi_free_QCryptoBlockCreateOptions(create_opts);
 365     return ret;
 366 }
 367
 368 static int block_crypto_truncate(BlockDriverState *bs, int64_t offset,
 369                                  PreallocMode prealloc, Error **errp)
 370 {
 371     BlockCrypto *crypto = bs->opaque;
 372     uint64_t payload_offset =
 373         qcrypto_block_get_payload_offset(crypto->block);
 374     assert(payload_offset < (INT64_MAX - offset));
 375
 376     offset += payload_offset;
 377
 378     return bdrv_truncate(bs->file, offset, prealloc, errp);
 379 }
 380
 381 static void block_crypto_close(BlockDriverState *bs)
 382 {
 383     BlockCrypto *crypto = bs->opaque;
 384     qcrypto_block_free(crypto->block);
 385 }
 386
 387
 388 /*
 389  * 1 MB bounce buffer gives good performance / memory tradeoff
 390  * when using cache=none|directsync.
 391  */
 392 #define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024)
 393
 394 static coroutine_fn int
 395 block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 396                        QEMUIOVector *qiov, int flags)
 397 {
 398     BlockCrypto *crypto = bs->opaque;
 399     uint64_t cur_bytes; /* number of bytes in current iteration */
 400     uint64_t bytes_done = 0;
 401     uint8_t *cipher_data = NULL;
 402     QEMUIOVector hd_qiov;
 403     int ret = 0;
 404     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 405     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 406
 407     assert(!flags);
 408     assert(payload_offset < INT64_MAX);
 409     assert(QEMU_IS_ALIGNED(offset, sector_size));
 410     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 411
 412     qemu_iovec_init(&hd_qiov, qiov->niov);
 413
 414     /* Bounce buffer because we don't wish to expose cipher text
 415      * in qiov which points to guest memory.
 416      */
 417     cipher_data =
 418         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 419                                               qiov->size));
 420     if (cipher_data == NULL) {
 421         ret = -ENOMEM;
 422         goto cleanup;
 423     }
 424
 425     while (bytes) {
 426         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 427
 428         qemu_iovec_reset(&hd_qiov);
 429         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 430
 431         ret = bdrv_co_preadv(bs->file, payload_offset + offset + bytes_done,
 432                              cur_bytes, &hd_qiov, 0);
 433         if (ret < 0) {
 434             goto cleanup;
 435         }
 436
 437         if (qcrypto_block_decrypt(crypto->block, offset + bytes_done,
 438                                   cipher_data, cur_bytes, NULL) < 0) {
 439             ret = -EIO;
 440             goto cleanup;
 441         }
 442
 443         qemu_iovec_from_buf(qiov, bytes_done, cipher_data, cur_bytes);
 444
 445         bytes -= cur_bytes;
 446         bytes_done += cur_bytes;
 447     }
 448
 449  cleanup:
 450     qemu_iovec_destroy(&hd_qiov);
 451     qemu_vfree(cipher_data);
 452
 453     return ret;
 454 }
 455
 456
 457 static coroutine_fn int
 458 block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 459                         QEMUIOVector *qiov, int flags)
 460 {
 461     BlockCrypto *crypto = bs->opaque;
 462     uint64_t cur_bytes; /* number of bytes in current iteration */
 463     uint64_t bytes_done = 0;
 464     uint8_t *cipher_data = NULL;
 465     QEMUIOVector hd_qiov;
 466     int ret = 0;
 467     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 468     uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
 469
 470     assert(!(flags & ~BDRV_REQ_FUA));
 471     assert(payload_offset < INT64_MAX);
 472     assert(QEMU_IS_ALIGNED(offset, sector_size));
 473     assert(QEMU_IS_ALIGNED(bytes, sector_size));
 474
 475     qemu_iovec_init(&hd_qiov, qiov->niov);
 476
 477     /* Bounce buffer because we're not permitted to touch
 478      * contents of qiov - it points to guest memory.
 479      */
 480     cipher_data =
 481         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
 482                                               qiov->size));
 483     if (cipher_data == NULL) {
 484         ret = -ENOMEM;
 485         goto cleanup;
 486     }
 487
 488     while (bytes) {
 489         cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
 490
 491         qemu_iovec_to_buf(qiov, bytes_done, cipher_data, cur_bytes);
 492
 493         if (qcrypto_block_encrypt(crypto->block, offset + bytes_done,
 494                                   cipher_data, cur_bytes, NULL) < 0) {
 495             ret = -EIO;
 496             goto cleanup;
 497         }
 498
 499         qemu_iovec_reset(&hd_qiov);
 500         qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
 501
 502         ret = bdrv_co_pwritev(bs->file, payload_offset + offset + bytes_done,
 503                               cur_bytes, &hd_qiov, flags);
 504         if (ret < 0) {
 505             goto cleanup;
 506         }
 507
 508         bytes -= cur_bytes;
 509         bytes_done += cur_bytes;
 510     }
 511
 512  cleanup:
 513     qemu_iovec_destroy(&hd_qiov);
 514     qemu_vfree(cipher_data);
 515
 516     return ret;
 517 }
 518
 519 static void block_crypto_refresh_limits(BlockDriverState *bs, Error **errp)
 520 {
 521     BlockCrypto *crypto = bs->opaque;
 522     uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
 523     bs->bl.request_alignment = sector_size; /* No sub-sector I/O */
 524 }
 525
 526
 527 static int64_t block_crypto_getlength(BlockDriverState *bs)
 528 {
 529     BlockCrypto *crypto = bs->opaque;
 530     int64_t len = bdrv_getlength(bs->file->bs);
 531
 532     uint64_t offset = qcrypto_block_get_payload_offset(crypto->block);
 533     assert(offset < INT64_MAX);
 534     assert(offset < len);
 535
 536     len -= offset;
 537
 538     return len;
 539 }
 540
 541
 542 static int block_crypto_probe_luks(const uint8_t *buf,
 543                                    int buf_size,
 544                                    const char *filename) {
 545     return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 546                                       buf, buf_size, filename);
 547 }
 548
 549 static int block_crypto_open_luks(BlockDriverState *bs,
 550                                   QDict *options,
 551                                   int flags,
 552                                   Error **errp)
 553 {
 554     return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 555                                      &block_crypto_runtime_opts_luks,
 556                                      bs, options, flags, errp);
 557 }
 558
 559 static int block_crypto_create_luks(const char *filename,
 560                                     QemuOpts *opts,
 561                                     Error **errp)
 562 {
 563     return block_crypto_create_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 564                                        filename, opts, errp);
 565 }
 566
 567 static int block_crypto_get_info_luks(BlockDriverState *bs,
 568                                       BlockDriverInfo *bdi)
 569 {
 570     BlockDriverInfo subbdi;
 571     int ret;
 572
 573     ret = bdrv_get_info(bs->file->bs, &subbdi);
 574     if (ret != 0) {
 575         return ret;
 576     }
 577
 578     bdi->unallocated_blocks_are_zero = false;
 579     bdi->cluster_size = subbdi.cluster_size;
 580
 581     return 0;
 582 }
 583
 584 static ImageInfoSpecific *
 585 block_crypto_get_specific_info_luks(BlockDriverState *bs)
 586 {
 587     BlockCrypto *crypto = bs->opaque;
 588     ImageInfoSpecific *spec_info;
 589     QCryptoBlockInfo *info;
 590
 591     info = qcrypto_block_get_info(crypto->block, NULL);
 592     if (!info) {
 593         return NULL;
 594     }
 595     if (info->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
 596         qapi_free_QCryptoBlockInfo(info);
 597         return NULL;
 598     }
 599
 600     spec_info = g_new(ImageInfoSpecific, 1);
 601     spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
 602     spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
 603     *spec_info->u.luks.data = info->u.luks;
 604
 605     /* Blank out pointers we've just stolen to avoid double free */
 606     memset(&info->u.luks, 0, sizeof(info->u.luks));
 607
 608     qapi_free_QCryptoBlockInfo(info);
 609
 610     return spec_info;
 611 }
 612
 613 BlockDriver bdrv_crypto_luks = {
 614     .format_name        = "luks",
 615     .instance_size      = sizeof(BlockCrypto),
 616     .bdrv_probe         = block_crypto_probe_luks,
 617     .bdrv_open          = block_crypto_open_luks,
 618     .bdrv_close         = block_crypto_close,
 619     .bdrv_child_perm    = bdrv_format_default_perms,
 620     .bdrv_create        = block_crypto_create_luks,
 621     .bdrv_truncate      = block_crypto_truncate,
 622     .create_opts        = &block_crypto_create_opts_luks,
 623
 624     .bdrv_refresh_limits = block_crypto_refresh_limits,
 625     .bdrv_co_preadv     = block_crypto_co_preadv,
 626     .bdrv_co_pwritev    = block_crypto_co_pwritev,
 627     .bdrv_getlength     = block_crypto_getlength,
 628     .bdrv_get_info      = block_crypto_get_info_luks,
 629     .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
 630 };
 631
 632 static void block_crypto_init(void)
 633 {
 634     bdrv_register(&bdrv_crypto_luks);
 635 }
 636
 637 block_init(block_crypto_init);