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>
140 lines
5.2 KiB
Python
Executable File
140 lines
5.2 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Test json:{} filenames with qemu-internal BDSs
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# (the one of commit, to be precise)
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#
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# Copyright (C) 2018 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: Max Reitz <mreitz@redhat.com>
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import iotests
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from iotests import log, qemu_img, qemu_io_silent, filter_qmp_testfiles, \
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filter_qmp_imgfmt
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import json
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# Need backing file support (for arbitrary backing formats)
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iotests.script_initialize(supported_fmts=['qcow2', 'qcow', 'qed'],
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supported_platforms=['linux'])
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# There are two variations of this test:
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# (1) We do not set filter_node_name. In that case, the commit_top
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# driver should not appear anywhere.
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# (2) We do set filter_node_name. In that case, it should appear.
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#
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# This for loop executes both.
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for filter_node_name in False, True:
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log('')
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log('--- filter_node_name: %s ---' % filter_node_name)
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log('')
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with iotests.FilePath('base.img') as base_img_path, \
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iotests.FilePath('mid.img') as mid_img_path, \
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iotests.FilePath('top.img') as top_img_path, \
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iotests.VM() as vm:
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assert qemu_img('create', '-f', iotests.imgfmt,
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base_img_path, '64M') == 0
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assert qemu_img('create', '-f', iotests.imgfmt, '-b', base_img_path,
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'-F', iotests.imgfmt, mid_img_path) == 0
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assert qemu_img('create', '-f', iotests.imgfmt, '-b', mid_img_path,
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'-F', iotests.imgfmt, top_img_path) == 0
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# Something to commit
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assert qemu_io_silent(mid_img_path, '-c', 'write -P 1 0 1M') == 0
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vm.launch()
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# Change the bottom-most image's backing file (to null-co://)
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# to enforce json:{} filenames
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vm.qmp_log('blockdev-add',
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node_name='top',
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driver=iotests.imgfmt,
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file={
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'driver': 'file',
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'filename': top_img_path
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},
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backing={
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'node-name': 'mid',
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'driver': iotests.imgfmt,
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'file': {
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'driver': 'file',
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'filename': mid_img_path
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},
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'backing': {
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'node-name': 'base',
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'driver': iotests.imgfmt,
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'file': {
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'driver': 'file',
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'filename': base_img_path
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},
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'backing': {
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'driver': 'null-co'
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}
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}
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},
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filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
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# As long as block-commit does not accept node names, we have to
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# get our mid/base filenames here
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mid_name = vm.node_info('mid')['image']['filename']
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base_name = vm.node_info('base')['image']['filename']
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assert mid_name[:5] == 'json:'
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assert base_name[:5] == 'json:'
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# Start the block job
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if filter_node_name:
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vm.qmp_log('block-commit',
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job_id='commit',
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device='top',
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filter_node_name='filter_node',
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top=mid_name,
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base=base_name,
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speed=1,
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filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
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else:
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vm.qmp_log('block-commit',
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job_id='commit',
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device='top',
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top=mid_name,
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base=base_name,
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speed=1,
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filters=[filter_qmp_testfiles, filter_qmp_imgfmt])
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vm.qmp_log('job-pause', id='commit')
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# Get and parse top's json:{} filename
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top_name = vm.node_info('top')['image']['filename']
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vm.shutdown()
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assert top_name[:5] == 'json:'
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top_options = json.loads(top_name[5:])
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if filter_node_name:
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# This should be present and set
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assert top_options['backing']['driver'] == 'commit_top'
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# And the mid image is commit_top's backing image
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mid_options = top_options['backing']['backing']
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else:
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# The mid image should appear as the immediate backing BDS
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# of top
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mid_options = top_options['backing']
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assert mid_options['driver'] == iotests.imgfmt
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assert mid_options['file']['filename'] == mid_img_path
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