b66ff2c298
There are many existing qcow2 images that specify a backing file but no format. This has been the source of CVEs in the past, but has become more prominent of a problem now that libvirt has switched to -blockdev. With older -drive, at least the probing was always done by qemu (so the only risk of a changed format between successive boots of a guest was if qemu was upgraded and probed differently). But with newer -blockdev, libvirt must specify a format; if libvirt guesses raw where the image was formatted, this results in data corruption visible to the guest; conversely, if libvirt guesses qcow2 where qemu was using raw, this can result in potential security holes, so modern libvirt instead refuses to use images without explicit backing format. The change in libvirt to reject images without explicit backing format has pointed out that a number of tools have been far too reliant on probing in the past. It's time to set a better example in our own iotests of properly setting this parameter. iotest calls to create, rebase, and convert are all impacted to some degree. It's a bit annoying that we are inconsistent on command line - while all of those accept -o backing_file=...,backing_fmt=..., the shortcuts are different: create and rebase have -b and -F, while convert has -B but no -F. (amend has no shortcuts, but the previous patch just deprecated the use of amend to change backing chains). Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200706203954.341758-9-eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
62 lines
2.8 KiB
Plaintext
62 lines
2.8 KiB
Plaintext
QA output created by 290
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### Test 'qemu-io -c discard' on a QCOW2 image without a backing file
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# Create an image with compat=0.10 without a backing file
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
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# Fill all clusters with data and then discard them
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wrote 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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discard 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Read the data from the discarded clusters
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read 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Output of qemu-img map
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Offset Length Mapped to File
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# Create an image with compat=1.1 without a backing file
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
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# Fill all clusters with data and then discard them
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wrote 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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discard 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Read the data from the discarded clusters
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read 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Output of qemu-img map
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Offset Length Mapped to File
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### Test 'qemu-io -c discard' on a QCOW2 image with a backing file
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# Create a backing image and fill it with data
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Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=131072
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wrote 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Create an image with compat=0.10 and a backing file
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
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# Fill all clusters with data and then discard them
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wrote 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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discard 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Read the data from the discarded clusters
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read 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Output of qemu-img map
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Offset Length Mapped to File
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0 0x20000 0x50000 TEST_DIR/t.qcow2
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# Create an image with compat=1.1 and a backing file
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
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# Fill all clusters with data and then discard them
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wrote 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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discard 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Read the data from the discarded clusters
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read 131072/131072 bytes at offset 0
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128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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# Output of qemu-img map
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Offset Length Mapped to File
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*** done
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