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>
146 lines
3.8 KiB
Bash
Executable file
146 lines
3.8 KiB
Bash
Executable file
#!/usr/bin/env bash
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#
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# Commit changes to backing file
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#
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# Copyright (C) 2009 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
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owner=kwolf@redhat.com
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seq=`basename $0`
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echo "QA output created by $seq"
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status=1 # failure is the default!
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_cleanup()
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{
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_cleanup_test_img
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_rm_test_img "$TEST_IMG.base"
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_rm_test_img "$TEST_IMG.orig"
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}
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trap "_cleanup; exit \$status" 0 1 2 3 15
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# get standard environment, filters and checks
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. ./common.rc
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. ./common.filter
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. ./common.pattern
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# Any format supporting backing files
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_supported_fmt qcow qcow2 vmdk qed
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_supported_proto file
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_unsupported_imgopts "subformat=monolithicFlat" \
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"subformat=twoGbMaxExtentFlat" \
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"subformat=twoGbMaxExtentSparse" \
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"subformat=streamOptimized"
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TEST_OFFSETS="0 4294967296"
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TEST_IMG_SAVE="$TEST_IMG"
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TEST_IMG="$TEST_IMG.base"
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_make_test_img 6G
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echo "Filling base image"
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echo
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for offset in $TEST_OFFSETS; do
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# Some clusters with alternating backing file/image file reads
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io writev $(( offset )) 512 1024 64
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# Complete backing clusters
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io writev $(( offset + 64 * 1024)) 65536 65536 1
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done
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_check_test_img
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echo "Creating test image with backing file"
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echo
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TEST_IMG="$TEST_IMG_SAVE"
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_make_test_img -b "$TEST_IMG.base" -F $IMGFMT 6G
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echo "Filling test image"
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echo
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for offset in $TEST_OFFSETS; do
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# Some clusters with alternating backing file/image file reads
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io writev $(( offset + 512 )) 512 1024 64
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# Complete test image clusters
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io writev $(( offset + 64 * 1024 + 65536)) 65536 65536 1
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done
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_check_test_img
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$QEMU_IMG commit "$TEST_IMG"
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TEST_IMG="$TEST_IMG.base"
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echo "Reading from the backing file"
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echo
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for offset in $TEST_OFFSETS; do
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# Some clusters with alternating backing file/image file reads
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io readv $(( offset )) 512 1024 64
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io readv $(( offset + 512 )) 512 1024 64
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# Complete test image clusters
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io readv $(( offset + 64 * 1024)) 65536 65536 1
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io readv $(( offset + 64 * 1024 + 65536)) 65536 65536 1
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# Empty sectors
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io_zero readv $(( offset + 64 * 1024 + 65536 * 4 )) 65536 65536 1
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done
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_check_test_img
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_cleanup
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TEST_IMG=$TEST_IMG_SAVE
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echo
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echo 'Testing failing commit'
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echo
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TEST_IMG="$TEST_IMG.base" _make_test_img 1M
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# Create an image with a null backing file to which committing will fail (with
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# ENOSPC so we can distinguish the result from some generic EIO which may be
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# generated anywhere in the block layer)
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backing="json:{'driver': '$IMGFMT',
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'file': {
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'driver': 'blkdebug',
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'inject-error': [{
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'event': 'write_aio',
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'errno': 28,
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'once': true
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}],
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'image': {
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'driver': 'file',
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'filename': '$TEST_IMG.base'
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}}}"
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# Filter out newlines and collapse spaces
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backing=$(echo "$backing" | tr -d '\n' | tr -s ' ')
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_make_test_img -b "$backing" -F $IMGFMT
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# Just write anything so committing will not be a no-op
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$QEMU_IO -c 'writev 0 64k' "$TEST_IMG" | _filter_qemu_io
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$QEMU_IMG commit "$TEST_IMG"
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_cleanup
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# success, all done
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echo "*** done"
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rm -f $seq.full
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status=0
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