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crypto.c: cleanup created file when block_crypto_co_create_opts_luks fails

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When using a non-UTF8 secret to create a volume using qemu-img, the
following error happens:

$ qemu-img create -f luks --object secret,id=vol_1_encrypt0,file=vol_resize_pool.vol_1.secret.qzVQrI -o key-secret=vol_1_encrypt0 /var/tmp/pool_target/vol_1 10240K

Formatting '/var/tmp/pool_target/vol_1', fmt=luks size=10485760 key-secret=vol_1_encrypt0
qemu-img: /var/tmp/pool_target/vol_1: Data from secret vol_1_encrypt0 is not valid UTF-8

However, the created file '/var/tmp/pool_target/vol_1' is left behind in the
file system after the failure. This behavior can be observed when creating
the volume using Libvirt, via 'virsh vol-create', and then getting "volume
target path already exist" errors when trying to re-create the volume.

The volume file is created inside block_crypto_co_create_opts_luks(), in
block/crypto.c. If the bdrv_create_file() call is successful but any
succeeding step fails*, the existing 'fail' label does not take into
account the created file, leaving it behind.

This patch changes block_crypto_co_create_opts_luks() to delete
'filename' in case of failure. A failure in this point means that
the volume is now truncated/corrupted, so even if 'filename' was an
existing volume before calling qemu-img, it is now unusable. Deleting
the file it is not much worse than leaving it in the filesystem in
this scenario, and we don't have to deal with checking the file
pre-existence in the code.

* in our case, block_crypto_co_create_generic calls qcrypto_block_create,
which calls qcrypto_block_luks_create, and this function fails when
calling qcrypto_secret_lookup_as_utf8.

Reported-by: Srikanth Aithal <bssrikanth@in.ibm.com>
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20200130213907.2830642-4-danielhb413@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Daniel Henrique Barboza 2020-01-30 18:39:06 -03:00 committed by Kevin Wolf
parent e1d7f8bb1e
commit 1bba30da24
1 changed files with 18 additions and 0 deletions
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18
block/crypto.c
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@ -30,6 +30,7 @@
#include "qapi/error.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "qemu/cutils.h"
#include "crypto.h"
typedef struct BlockCrypto BlockCrypto;
@ -596,6 +597,23 @@ static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
ret = 0;
fail:
/*
* If an error occurred, delete 'filename'. Even if the file existed
* beforehand, it has been truncated and corrupted in the process.
*/
if (ret && bs) {
Error *local_delete_err = NULL;
int r_del = bdrv_co_delete_file(bs, &local_delete_err);
/*
* ENOTSUP will happen if the block driver doesn't support
* the 'bdrv_co_delete_file' interface. This is a predictable
* scenario and shouldn't be reported back to the user.
*/
if ((r_del < 0) && (r_del != -ENOTSUP)) {
error_report_err(local_delete_err);
}
}
bdrv_unref(bs);
qapi_free_QCryptoBlockCreateOptions(create_opts);
qobject_unref(cryptoopts);