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>
149 lines
4 KiB
Bash
Executable file
149 lines
4 KiB
Bash
Executable file
#!/usr/bin/env bash
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#
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# Test that backing files can be smaller than the image
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#
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# Copyright (C) 2010 IBM, Corp.
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#
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# Based on 017:
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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=stefanha@linux.vnet.ibm.com
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seq=`basename $0`
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echo "QA output created by $seq"
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status=1 # failure is the default!
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_cleanup()
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{
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_cleanup_qemu
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_rm_test_img "${TEST_IMG}.copy"
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_cleanup_test_img
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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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. ./common.qemu
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# Any format supporting backing files except vmdk and qcow which do not support
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# smaller backing files.
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_supported_fmt qcow2 qed
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_supported_proto file
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_supported_os Linux
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# Choose a size that is not necessarily a cluster size multiple for image
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# formats that use clusters. This will ensure that the base image doesn't end
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# precisely on a cluster boundary (the easy case).
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image_size=$(( 4 * 1024 * 1024 * 1024 + 3 * 512 ))
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# The base image is smaller than the image file
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base_size=$(( image_size - 1024 * 1024 * 1024 ))
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offset=$(( base_size - 32 * 1024 ))
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TEST_IMG_SAVE="$TEST_IMG"
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TEST_IMG="$TEST_IMG.base"
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_make_test_img $base_size
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echo "Filling base image"
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echo
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# Fill end of base image with a pattern, skipping every other sector
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io writev $offset 512 1024 32
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_check_test_img
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echo "Creating test image with backing file"
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echo
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TEST_IMG="$TEST_IMG_SAVE"
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_make_test_img -b "$TEST_IMG.base" -F $IMGFMT $image_size
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echo "Filling test image"
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echo
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# Write every other sector around where the base image ends
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io writev $(( offset + 512 )) 512 1024 64
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_check_test_img
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echo "Reading"
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echo
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# Base image sectors
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io readv $(( offset )) 512 1024 32
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# Image sectors
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io readv $(( offset + 512 )) 512 1024 64
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# Zero sectors beyond end of base image
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io_zero readv $(( offset + 32 * 1024 )) 512 1024 32
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_check_test_img
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# Rebase it on top of its base image
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$QEMU_IMG rebase -b "$TEST_IMG.base" -F $IMGFMT "$TEST_IMG"
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echo
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echo block-backup
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echo
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qemu_comm_method="monitor"
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_launch_qemu -drive file="${TEST_IMG}",cache=${CACHEMODE},aio=${AIOMODE},id=disk
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h=$QEMU_HANDLE
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if [ "${VALGRIND_QEMU}" == "y" ]; then
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QEMU_COMM_TIMEOUT=7
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else
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QEMU_COMM_TIMEOUT=1
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fi
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# Silence output since it contains the disk image path and QEMU's readline
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# character echoing makes it very hard to filter the output. Plus, there
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# is no telling how many times the command will repeat before succeeding.
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# (Note that creating the image results in a "Formatting..." message over
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# stdout, which is the same channel the monitor uses. We cannot reliably
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# wait for it because the monitor output may interact with it in such a
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# way that _timed_wait_for cannot read it. However, once the block job is
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# done, we know that the "Formatting..." message must have appeared
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# already, so the output is still deterministic.)
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silent=y _send_qemu_cmd $h "drive_backup disk ${TEST_IMG}.copy" "(qemu)"
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silent=y qemu_cmd_repeat=20 _send_qemu_cmd $h "info block-jobs" "No active jobs"
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_send_qemu_cmd $h "info block-jobs" "No active jobs"
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_send_qemu_cmd $h 'quit' ""
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# Base image sectors
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TEST_IMG="${TEST_IMG}.copy" io readv $(( offset )) 512 1024 32
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# Image sectors
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TEST_IMG="${TEST_IMG}.copy" io readv $(( offset + 512 )) 512 1024 64
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# Zero sectors beyond end of base image
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TEST_IMG="${TEST_IMG}.copy" io_zero readv $(( offset + 32 * 1024 )) 512 1024 32
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_check_test_img
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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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