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author | Stefan Hajnoczi <stefanha@redhat.com> | 2019-02-18 10:45:24 +0000 |
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committer | Max Reitz <mreitz@redhat.com> | 2019-02-25 15:11:28 +0100 |
commit | 61914f8906fabbae26372a576d9dd988c5e22b75 (patch) | |
tree | b820fc218ba85f7912764924cee8218e512e16e4 /block | |
parent | 8a57a4be8389073d8bdb5d5d22e50d6282a36df0 (diff) | |
download | qemu-61914f8906fabbae26372a576d9dd988c5e22b75.zip qemu-61914f8906fabbae26372a576d9dd988c5e22b75.tar.gz qemu-61914f8906fabbae26372a576d9dd988c5e22b75.tar.bz2 |
qcow2: include LUKS payload overhead in qemu-img measure
LUKS encryption reserves clusters for its own payload data. The size of
this area must be included in the qemu-img measure calculation so that
we arrive at the correct minimum required image size.
(Ab)use the qcrypto_block_create() API to determine the payload
overhead. We discard the payload data that qcrypto thinks will be
written to the image.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190218104525.23674-2-stefanha@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block')
-rw-r--r-- | block/qcow2.c | 72 |
1 files changed, 71 insertions, 1 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 92242fb..1de5e24 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4236,6 +4236,60 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) return ret; } +static ssize_t qcow2_measure_crypto_hdr_init_func(QCryptoBlock *block, + size_t headerlen, void *opaque, Error **errp) +{ + size_t *headerlenp = opaque; + + /* Stash away the payload size */ + *headerlenp = headerlen; + return 0; +} + +static ssize_t qcow2_measure_crypto_hdr_write_func(QCryptoBlock *block, + size_t offset, const uint8_t *buf, size_t buflen, + void *opaque, Error **errp) +{ + /* Discard the bytes, we're not actually writing to an image */ + return buflen; +} + +/* Determine the number of bytes for the LUKS payload */ +static bool qcow2_measure_luks_headerlen(QemuOpts *opts, size_t *len, + Error **errp) +{ + QDict *opts_qdict; + QDict *cryptoopts_qdict; + QCryptoBlockCreateOptions *cryptoopts; + QCryptoBlock *crypto; + + /* Extract "encrypt." options into a qdict */ + opts_qdict = qemu_opts_to_qdict(opts, NULL); + qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt."); + qobject_unref(opts_qdict); + + /* Build QCryptoBlockCreateOptions object from qdict */ + qdict_put_str(cryptoopts_qdict, "format", "luks"); + cryptoopts = block_crypto_create_opts_init(cryptoopts_qdict, errp); + qobject_unref(cryptoopts_qdict); + if (!cryptoopts) { + return false; + } + + /* Fake LUKS creation in order to determine the payload size */ + crypto = qcrypto_block_create(cryptoopts, "encrypt.", + qcow2_measure_crypto_hdr_init_func, + qcow2_measure_crypto_hdr_write_func, + len, errp); + qapi_free_QCryptoBlockCreateOptions(cryptoopts); + if (!crypto) { + return false; + } + + qcrypto_block_free(crypto); + return true; +} + static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, Error **errp) { @@ -4245,11 +4299,13 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, uint64_t virtual_size; /* disk size as seen by guest */ uint64_t refcount_bits; uint64_t l2_tables; + uint64_t luks_payload_size = 0; size_t cluster_size; int version; char *optstr; PreallocMode prealloc; bool has_backing_file; + bool has_luks; /* Parse image creation options */ cluster_size = qcow2_opt_get_cluster_size_del(opts, &local_err); @@ -4279,6 +4335,20 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, has_backing_file = !!optstr; g_free(optstr); + optstr = qemu_opt_get_del(opts, BLOCK_OPT_ENCRYPT_FORMAT); + has_luks = optstr && strcmp(optstr, "luks") == 0; + g_free(optstr); + + if (has_luks) { + size_t headerlen; + + if (!qcow2_measure_luks_headerlen(opts, &headerlen, &local_err)) { + goto err; + } + + luks_payload_size = ROUND_UP(headerlen, cluster_size); + } + virtual_size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); virtual_size = ROUND_UP(virtual_size, cluster_size); @@ -4349,7 +4419,7 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, info = g_new(BlockMeasureInfo, 1); info->fully_allocated = qcow2_calc_prealloc_size(virtual_size, cluster_size, - ctz32(refcount_bits)); + ctz32(refcount_bits)) + luks_payload_size; /* Remove data clusters that are not required. This overestimates the * required size because metadata needed for the fully allocated file is |