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-visit.h"
  28 #include "qapi/error.h"
  29
  30 #define BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET "key-secret"
  31 #define BLOCK_CRYPTO_OPT_LUKS_CIPHER_ALG "cipher-alg"
  32 #define BLOCK_CRYPTO_OPT_LUKS_CIPHER_MODE "cipher-mode"
  33 #define BLOCK_CRYPTO_OPT_LUKS_IVGEN_ALG "ivgen-alg"
  34 #define BLOCK_CRYPTO_OPT_LUKS_IVGEN_HASH_ALG "ivgen-hash-alg"
  35 #define BLOCK_CRYPTO_OPT_LUKS_HASH_ALG "hash-alg"
  36
  37 typedef struct BlockCrypto BlockCrypto;
  38
  39 struct BlockCrypto {
  40     QCryptoBlock *block;
  41 };
  42
  43
  44 static int block_crypto_probe_generic(QCryptoBlockFormat format,
  45                                       const uint8_t *buf,
  46                                       int buf_size,
  47                                       const char *filename)
  48 {
  49     if (qcrypto_block_has_format(format, buf, buf_size)) {
  50         return 100;
  51     } else {
  52         return 0;
  53     }
  54 }
  55
  56
  57 static ssize_t block_crypto_read_func(QCryptoBlock *block,
  58                                       size_t offset,
  59                                       uint8_t *buf,
  60                                       size_t buflen,
  61                                       Error **errp,
  62                                       void *opaque)
  63 {
  64     BlockDriverState *bs = opaque;
  65     ssize_t ret;
  66
  67     ret = bdrv_pread(bs->file, offset, buf, buflen);
  68     if (ret < 0) {
  69         error_setg_errno(errp, -ret, "Could not read encryption header");
  70         return ret;
  71     }
  72     return ret;
  73 }
  74
  75
  76 struct BlockCryptoCreateData {
  77     const char *filename;
  78     QemuOpts *opts;
  79     BlockBackend *blk;
  80     uint64_t size;
  81 };
  82
  83
  84 static ssize_t block_crypto_write_func(QCryptoBlock *block,
  85                                        size_t offset,
  86                                        const uint8_t *buf,
  87                                        size_t buflen,
  88                                        Error **errp,
  89                                        void *opaque)
  90 {
  91     struct BlockCryptoCreateData *data = opaque;
  92     ssize_t ret;
  93
  94     ret = blk_pwrite(data->blk, offset, buf, buflen, 0);
  95     if (ret < 0) {
  96         error_setg_errno(errp, -ret, "Could not write encryption header");
  97         return ret;
  98     }
  99     return ret;
 100 }
 101
 102
 103 static ssize_t block_crypto_init_func(QCryptoBlock *block,
 104                                       size_t headerlen,
 105                                       Error **errp,
 106                                       void *opaque)
 107 {
 108     struct BlockCryptoCreateData *data = opaque;
 109     int ret;
 110
 111     /* User provided size should reflect amount of space made
 112      * available to the guest, so we must take account of that
 113      * which will be used by the crypto header
 114      */
 115     data->size += headerlen;
 116
 117     qemu_opt_set_number(data->opts, BLOCK_OPT_SIZE, data->size, &error_abort);
 118     ret = bdrv_create_file(data->filename, data->opts, errp);
 119     if (ret < 0) {
 120         return -1;
 121     }
 122
 123     data->blk = blk_new_open(data->filename, NULL, NULL,
 124                              BDRV_O_RDWR | BDRV_O_PROTOCOL, errp);
 125     if (!data->blk) {
 126         return -1;
 127     }
 128
 129     return 0;
 130 }
 131
 132
 133 static QemuOptsList block_crypto_runtime_opts_luks = {
 134     .name = "crypto",
 135     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_runtime_opts_luks.head),
 136     .desc = {
 137         {
 138             .name = BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET,
 139             .type = QEMU_OPT_STRING,
 140             .help = "ID of the secret that provides the encryption key",
 141         },
 142         { /* end of list */ }
 143     },
 144 };
 145
 146
 147 static QemuOptsList block_crypto_create_opts_luks = {
 148     .name = "crypto",
 149     .head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
 150     .desc = {
 151         {
 152             .name = BLOCK_OPT_SIZE,
 153             .type = QEMU_OPT_SIZE,
 154             .help = "Virtual disk size"
 155         },
 156         {
 157             .name = BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET,
 158             .type = QEMU_OPT_STRING,
 159             .help = "ID of the secret that provides the encryption key",
 160         },
 161         {
 162             .name = BLOCK_CRYPTO_OPT_LUKS_CIPHER_ALG,
 163             .type = QEMU_OPT_STRING,
 164             .help = "Name of encryption cipher algorithm",
 165         },
 166         {
 167             .name = BLOCK_CRYPTO_OPT_LUKS_CIPHER_MODE,
 168             .type = QEMU_OPT_STRING,
 169             .help = "Name of encryption cipher mode",
 170         },
 171         {
 172             .name = BLOCK_CRYPTO_OPT_LUKS_IVGEN_ALG,
 173             .type = QEMU_OPT_STRING,
 174             .help = "Name of IV generator algorithm",
 175         },
 176         {
 177             .name = BLOCK_CRYPTO_OPT_LUKS_IVGEN_HASH_ALG,
 178             .type = QEMU_OPT_STRING,
 179             .help = "Name of IV generator hash algorithm",
 180         },
 181         {
 182             .name = BLOCK_CRYPTO_OPT_LUKS_HASH_ALG,
 183             .type = QEMU_OPT_STRING,
 184             .help = "Name of encryption hash algorithm",
 185         },
 186         { /* end of list */ }
 187     },
 188 };
 189
 190
 191 static QCryptoBlockOpenOptions *
 192 block_crypto_open_opts_init(QCryptoBlockFormat format,
 193                             QemuOpts *opts,
 194                             Error **errp)
 195 {
 196     Visitor *v;
 197     QCryptoBlockOpenOptions *ret = NULL;
 198     Error *local_err = NULL;
 199
 200     ret = g_new0(QCryptoBlockOpenOptions, 1);
 201     ret->format = format;
 202
 203     v = opts_visitor_new(opts);
 204
 205     visit_start_struct(v, NULL, NULL, 0, &local_err);
 206     if (local_err) {
 207         goto out;
 208     }
 209
 210     switch (format) {
 211     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 212         visit_type_QCryptoBlockOptionsLUKS_members(
 213             v, &ret->u.luks, &local_err);
 214         break;
 215
 216     default:
 217         error_setg(&local_err, "Unsupported block format %d", format);
 218         break;
 219     }
 220     if (!local_err) {
 221         visit_check_struct(v, &local_err);
 222     }
 223
 224     visit_end_struct(v, NULL);
 225
 226  out:
 227     if (local_err) {
 228         error_propagate(errp, local_err);
 229         qapi_free_QCryptoBlockOpenOptions(ret);
 230         ret = NULL;
 231     }
 232     visit_free(v);
 233     return ret;
 234 }
 235
 236
 237 static QCryptoBlockCreateOptions *
 238 block_crypto_create_opts_init(QCryptoBlockFormat format,
 239                               QemuOpts *opts,
 240                               Error **errp)
 241 {
 242     Visitor *v;
 243     QCryptoBlockCreateOptions *ret = NULL;
 244     Error *local_err = NULL;
 245
 246     ret = g_new0(QCryptoBlockCreateOptions, 1);
 247     ret->format = format;
 248
 249     v = opts_visitor_new(opts);
 250
 251     visit_start_struct(v, NULL, NULL, 0, &local_err);
 252     if (local_err) {
 253         goto out;
 254     }
 255
 256     switch (format) {
 257     case Q_CRYPTO_BLOCK_FORMAT_LUKS:
 258         visit_type_QCryptoBlockCreateOptionsLUKS_members(
 259             v, &ret->u.luks, &local_err);
 260         break;
 261
 262     default:
 263         error_setg(&local_err, "Unsupported block format %d", format);
 264         break;
 265     }
 266     if (!local_err) {
 267         visit_check_struct(v, &local_err);
 268     }
 269
 270     visit_end_struct(v, NULL);
 271
 272  out:
 273     if (local_err) {
 274         error_propagate(errp, local_err);
 275         qapi_free_QCryptoBlockCreateOptions(ret);
 276         ret = NULL;
 277     }
 278     visit_free(v);
 279     return ret;
 280 }
 281
 282
 283 static int block_crypto_open_generic(QCryptoBlockFormat format,
 284                                      QemuOptsList *opts_spec,
 285                                      BlockDriverState *bs,
 286                                      QDict *options,
 287                                      int flags,
 288                                      Error **errp)
 289 {
 290     BlockCrypto *crypto = bs->opaque;
 291     QemuOpts *opts = NULL;
 292     Error *local_err = NULL;
 293     int ret = -EINVAL;
 294     QCryptoBlockOpenOptions *open_opts = NULL;
 295     unsigned int cflags = 0;
 296
 297     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
 298     qemu_opts_absorb_qdict(opts, options, &local_err);
 299     if (local_err) {
 300         error_propagate(errp, local_err);
 301         goto cleanup;
 302     }
 303
 304     open_opts = block_crypto_open_opts_init(format, opts, errp);
 305     if (!open_opts) {
 306         goto cleanup;
 307     }
 308
 309     if (flags & BDRV_O_NO_IO) {
 310         cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
 311     }
 312     crypto->block = qcrypto_block_open(open_opts,
 313                                        block_crypto_read_func,
 314                                        bs,
 315                                        cflags,
 316                                        errp);
 317
 318     if (!crypto->block) {
 319         ret = -EIO;
 320         goto cleanup;
 321     }
 322
 323     bs->encrypted = true;
 324     bs->valid_key = true;
 325
 326     ret = 0;
 327  cleanup:
 328     qapi_free_QCryptoBlockOpenOptions(open_opts);
 329     return ret;
 330 }
 331
 332
 333 static int block_crypto_create_generic(QCryptoBlockFormat format,
 334                                        const char *filename,
 335                                        QemuOpts *opts,
 336                                        Error **errp)
 337 {
 338     int ret = -EINVAL;
 339     QCryptoBlockCreateOptions *create_opts = NULL;
 340     QCryptoBlock *crypto = NULL;
 341     struct BlockCryptoCreateData data = {
 342         .size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
 343                          BDRV_SECTOR_SIZE),
 344         .opts = opts,
 345         .filename = filename,
 346     };
 347
 348     create_opts = block_crypto_create_opts_init(format, opts, errp);
 349     if (!create_opts) {
 350         return -1;
 351     }
 352
 353     crypto = qcrypto_block_create(create_opts,
 354                                   block_crypto_init_func,
 355                                   block_crypto_write_func,
 356                                   &data,
 357                                   errp);
 358
 359     if (!crypto) {
 360         ret = -EIO;
 361         goto cleanup;
 362     }
 363
 364     ret = 0;
 365  cleanup:
 366     qcrypto_block_free(crypto);
 367     blk_unref(data.blk);
 368     qapi_free_QCryptoBlockCreateOptions(create_opts);
 369     return ret;
 370 }
 371
 372 static int block_crypto_truncate(BlockDriverState *bs, int64_t offset)
 373 {
 374     BlockCrypto *crypto = bs->opaque;
 375     size_t payload_offset =
 376         qcrypto_block_get_payload_offset(crypto->block);
 377
 378     offset += payload_offset;
 379
 380     return bdrv_truncate(bs->file->bs, offset);
 381 }
 382
 383 static void block_crypto_close(BlockDriverState *bs)
 384 {
 385     BlockCrypto *crypto = bs->opaque;
 386     qcrypto_block_free(crypto->block);
 387 }
 388
 389
 390 #define BLOCK_CRYPTO_MAX_SECTORS 32
 391
 392 static coroutine_fn int
 393 block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num,
 394                       int remaining_sectors, QEMUIOVector *qiov)
 395 {
 396     BlockCrypto *crypto = bs->opaque;
 397     int cur_nr_sectors; /* number of sectors in current iteration */
 398     uint64_t bytes_done = 0;
 399     uint8_t *cipher_data = NULL;
 400     QEMUIOVector hd_qiov;
 401     int ret = 0;
 402     size_t payload_offset =
 403         qcrypto_block_get_payload_offset(crypto->block) / 512;
 404
 405     qemu_iovec_init(&hd_qiov, qiov->niov);
 406
 407     /* Bounce buffer so we have a linear mem region for
 408      * entire sector. XXX optimize so we avoid bounce
 409      * buffer in case that qiov->niov == 1
 410      */
 411     cipher_data =
 412         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512,
 413                                               qiov->size));
 414     if (cipher_data == NULL) {
 415         ret = -ENOMEM;
 416         goto cleanup;
 417     }
 418
 419     while (remaining_sectors) {
 420         cur_nr_sectors = remaining_sectors;
 421
 422         if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) {
 423             cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS;
 424         }
 425
 426         qemu_iovec_reset(&hd_qiov);
 427         qemu_iovec_add(&hd_qiov, cipher_data, cur_nr_sectors * 512);
 428
 429         ret = bdrv_co_readv(bs->file,
 430                             payload_offset + sector_num,
 431                             cur_nr_sectors, &hd_qiov);
 432         if (ret < 0) {
 433             goto cleanup;
 434         }
 435
 436         if (qcrypto_block_decrypt(crypto->block,
 437                                   sector_num,
 438                                   cipher_data, cur_nr_sectors * 512,
 439                                   NULL) < 0) {
 440             ret = -EIO;
 441             goto cleanup;
 442         }
 443
 444         qemu_iovec_from_buf(qiov, bytes_done,
 445                             cipher_data, cur_nr_sectors * 512);
 446
 447         remaining_sectors -= cur_nr_sectors;
 448         sector_num += cur_nr_sectors;
 449         bytes_done += cur_nr_sectors * 512;
 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_writev(BlockDriverState *bs, int64_t sector_num,
 462                        int remaining_sectors, QEMUIOVector *qiov)
 463 {
 464     BlockCrypto *crypto = bs->opaque;
 465     int cur_nr_sectors; /* number of sectors in current iteration */
 466     uint64_t bytes_done = 0;
 467     uint8_t *cipher_data = NULL;
 468     QEMUIOVector hd_qiov;
 469     int ret = 0;
 470     size_t payload_offset =
 471         qcrypto_block_get_payload_offset(crypto->block) / 512;
 472
 473     qemu_iovec_init(&hd_qiov, qiov->niov);
 474
 475     /* Bounce buffer so we have a linear mem region for
 476      * entire sector. XXX optimize so we avoid bounce
 477      * buffer in case that qiov->niov == 1
 478      */
 479     cipher_data =
 480         qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512,
 481                                               qiov->size));
 482     if (cipher_data == NULL) {
 483         ret = -ENOMEM;
 484         goto cleanup;
 485     }
 486
 487     while (remaining_sectors) {
 488         cur_nr_sectors = remaining_sectors;
 489
 490         if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) {
 491             cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS;
 492         }
 493
 494         qemu_iovec_to_buf(qiov, bytes_done,
 495                           cipher_data, cur_nr_sectors * 512);
 496
 497         if (qcrypto_block_encrypt(crypto->block,
 498                                   sector_num,
 499                                   cipher_data, cur_nr_sectors * 512,
 500                                   NULL) < 0) {
 501             ret = -EIO;
 502             goto cleanup;
 503         }
 504
 505         qemu_iovec_reset(&hd_qiov);
 506         qemu_iovec_add(&hd_qiov, cipher_data, cur_nr_sectors * 512);
 507
 508         ret = bdrv_co_writev(bs->file,
 509                              payload_offset + sector_num,
 510                              cur_nr_sectors, &hd_qiov);
 511         if (ret < 0) {
 512             goto cleanup;
 513         }
 514
 515         remaining_sectors -= cur_nr_sectors;
 516         sector_num += cur_nr_sectors;
 517         bytes_done += cur_nr_sectors * 512;
 518     }
 519
 520  cleanup:
 521     qemu_iovec_destroy(&hd_qiov);
 522     qemu_vfree(cipher_data);
 523
 524     return ret;
 525 }
 526
 527
 528 static int64_t block_crypto_getlength(BlockDriverState *bs)
 529 {
 530     BlockCrypto *crypto = bs->opaque;
 531     int64_t len = bdrv_getlength(bs->file->bs);
 532
 533     ssize_t offset = qcrypto_block_get_payload_offset(crypto->block);
 534
 535     len -= offset;
 536
 537     return len;
 538 }
 539
 540
 541 static int block_crypto_probe_luks(const uint8_t *buf,
 542                                    int buf_size,
 543                                    const char *filename) {
 544     return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 545                                       buf, buf_size, filename);
 546 }
 547
 548 static int block_crypto_open_luks(BlockDriverState *bs,
 549                                   QDict *options,
 550                                   int flags,
 551                                   Error **errp)
 552 {
 553     return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 554                                      &block_crypto_runtime_opts_luks,
 555                                      bs, options, flags, errp);
 556 }
 557
 558 static int block_crypto_create_luks(const char *filename,
 559                                     QemuOpts *opts,
 560                                     Error **errp)
 561 {
 562     return block_crypto_create_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
 563                                        filename, opts, errp);
 564 }
 565
 566 BlockDriver bdrv_crypto_luks = {
 567     .format_name        = "luks",
 568     .instance_size      = sizeof(BlockCrypto),
 569     .bdrv_probe         = block_crypto_probe_luks,
 570     .bdrv_open          = block_crypto_open_luks,
 571     .bdrv_close         = block_crypto_close,
 572     .bdrv_create        = block_crypto_create_luks,
 573     .bdrv_truncate      = block_crypto_truncate,
 574     .create_opts        = &block_crypto_create_opts_luks,
 575
 576     .bdrv_co_readv      = block_crypto_co_readv,
 577     .bdrv_co_writev     = block_crypto_co_writev,
 578     .bdrv_getlength     = block_crypto_getlength,
 579 };
 580
 581 static void block_crypto_init(void)
 582 {
 583     bdrv_register(&bdrv_crypto_luks);
 584 }
 585
 586 block_init(block_crypto_init);