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>
156 lines
6.1 KiB
Python
Executable file
156 lines
6.1 KiB
Python
Executable file
#!/usr/bin/env python3
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#
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# Copyright (C) 2019 Red Hat, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# Creator/Owner: Kevin Wolf <kwolf@redhat.com>
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#
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# Some tests for short backing files and short overlays
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import iotests
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iotests.script_initialize(supported_fmts=['qcow2'],
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supported_platforms=['linux'])
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size_short = 1 * 1024 * 1024
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size_long = 2 * 1024 * 1024
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size_diff = size_long - size_short
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def create_chain() -> None:
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iotests.qemu_img_log('create', '-f', iotests.imgfmt, base,
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str(size_long))
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iotests.qemu_img_log('create', '-f', iotests.imgfmt, '-b', base,
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'-F', iotests.imgfmt, mid, str(size_short))
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iotests.qemu_img_log('create', '-f', iotests.imgfmt, '-b', mid,
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'-F', iotests.imgfmt, top, str(size_long))
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iotests.qemu_io_log('-c', 'write -P 1 0 %d' % size_long, base)
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def create_vm() -> iotests.VM:
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vm = iotests.VM()
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vm.add_blockdev('file,filename=%s,node-name=base-file' % base)
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vm.add_blockdev('%s,file=base-file,node-name=base' % iotests.imgfmt)
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vm.add_blockdev('file,filename=%s,node-name=mid-file' % mid)
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vm.add_blockdev('%s,file=mid-file,node-name=mid,backing=base'
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% iotests.imgfmt)
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vm.add_drive(top, 'backing=mid,node-name=top')
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return vm
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with iotests.FilePath('base') as base, \
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iotests.FilePath('mid') as mid, \
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iotests.FilePath('top') as top:
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iotests.log('== Commit tests ==')
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create_chain()
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iotests.log('=== Check visible data ===')
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iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, top)
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iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), top)
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iotests.log('=== Checking allocation status ===')
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iotests.qemu_io_log('-c', 'alloc 0 %d' % size_short,
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'-c', 'alloc %d %d' % (size_short, size_diff),
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base)
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iotests.qemu_io_log('-c', 'alloc 0 %d' % size_short,
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'-c', 'alloc %d %d' % (size_short, size_diff),
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mid)
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iotests.qemu_io_log('-c', 'alloc 0 %d' % size_short,
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'-c', 'alloc %d %d' % (size_short, size_diff),
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top)
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iotests.log('=== Checking map ===')
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iotests.qemu_img_log('map', '--output=json', base)
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iotests.qemu_img_log('map', '--output=human', base)
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iotests.qemu_img_log('map', '--output=json', mid)
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iotests.qemu_img_log('map', '--output=human', mid)
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iotests.qemu_img_log('map', '--output=json', top)
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iotests.qemu_img_log('map', '--output=human', top)
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iotests.log('=== Testing qemu-img commit (top -> mid) ===')
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iotests.qemu_img_log('commit', top)
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iotests.img_info_log(mid)
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iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
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iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
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iotests.log('=== Testing HMP commit (top -> mid) ===')
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create_chain()
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with create_vm() as vm:
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vm.launch()
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vm.qmp_log('human-monitor-command', command_line='commit drive0')
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iotests.img_info_log(mid)
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iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
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iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
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iotests.log('=== Testing QMP active commit (top -> mid) ===')
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create_chain()
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with create_vm() as vm:
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vm.launch()
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vm.qmp_log('block-commit', device='top', base_node='mid',
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job_id='job0', auto_dismiss=False)
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vm.run_job('job0', wait=5)
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iotests.img_info_log(mid)
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iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
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iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
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iotests.log('== Resize tests ==')
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# Use different sizes for different allocation modes:
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#
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# We want to have at least one test where 32 bit truncation in the size of
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# the overlapping area becomes visible. This is covered by the
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# prealloc='off' case (1G to 6G is an overlap of 5G).
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#
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# However, we can only do this for modes that don't preallocate data
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# because otherwise we might run out of space on the test host.
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#
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# We also want to test some unaligned combinations.
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for (prealloc, base_size, top_size_old, top_size_new, off) in [
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('off', '6G', '1G', '8G', '5G'),
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('metadata', '32G', '30G', '33G', '31G'),
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('falloc', '10M', '5M', '15M', '9M'),
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('full', '16M', '8M', '12M', '11M'),
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('off', '384k', '253k', '512k', '253k'),
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('off', '400k', '256k', '512k', '336k'),
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('off', '512k', '256k', '500k', '436k')]:
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iotests.log('=== preallocation=%s ===' % prealloc)
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iotests.qemu_img_log('create', '-f', iotests.imgfmt, base, base_size)
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iotests.qemu_img_log('create', '-f', iotests.imgfmt, '-b', base,
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'-F', iotests.imgfmt, top, top_size_old)
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iotests.qemu_io_log('-c', 'write -P 1 %s 64k' % off, base)
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# After this, top_size_old to base_size should be allocated/zeroed.
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#
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# In theory, leaving base_size to top_size_new unallocated would be
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# correct, but in practice, if we zero out anything, we zero out
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# everything up to top_size_new.
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iotests.qemu_img_log('resize', '-f', iotests.imgfmt,
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'--preallocation', prealloc, top, top_size_new)
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iotests.qemu_io_log('-c', 'read -P 0 %s 64k' % off, top)
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iotests.qemu_io_log('-c', 'map', top)
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iotests.qemu_img_log('map', '--output=json', top)
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