qemu-e2k/tests/qemu-iotests/179
Eric Blake b66ff2c298 iotests: Specify explicit backing format where sensible
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>
2020-07-14 15:18:59 +02:00

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#!/usr/bin/env bash
#
# Test case for write zeroes with unmap
#
# Copyright (C) 2017 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# creator
owner=eblake@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
rm -f "$TEST_DIR/blkdebug.conf"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
_supported_fmt qcow2
_supported_proto file
_supported_os Linux
# v2 images can't mark clusters as zero
_unsupported_imgopts compat=0.10
echo
echo '=== Testing write zeroes with unmap ==='
echo
TEST_IMG="$TEST_IMG.base" _make_test_img 64M
_make_test_img -b "$TEST_IMG.base" -F $IMGFMT
# Offsets chosen at or near 2M boundaries so test works at all cluster sizes
# 8k and larger (smaller clusters fail due to non-contiguous allocations)
# Aligned writes to unallocated cluster should not allocate mapping, but must
# mark cluster as zero, whether or not unmap was requested
$QEMU_IO -c "write -z -u 2M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 6M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
# Unaligned writes need not allocate mapping if the cluster already reads
# as zero, but must mark cluster as zero, whether or not unmap was requested
$QEMU_IO -c "write -z -u 10485761 2097150" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 14680065 2097150" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
# Requesting unmap of normal data must deallocate; omitting unmap should
# preserve the mapping
$QEMU_IO -c "write 18M 14M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z -u 20M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 24M 6M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
# Likewise when writing on already-mapped zero data
$QEMU_IO -c "write -z -u 26M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 28M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
# Writing on unmapped zeroes does not allocate
$QEMU_IO -c "write -z 32M 8M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z -u 34M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 36M 2M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
# Writing zero overrides a backing file, regardless of backing cluster type
$QEMU_IO -c "write -z 40M 8M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write 48M 8M" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z -u 42M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 44M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z -u 50M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 52M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z -u 58M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 60M 2M" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "map" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Final check that mappings are correct and images are still sane
TEST_IMG="$TEST_IMG.base" _check_test_img
_check_test_img
echo
echo '=== Testing cache optimization ==='
echo
BLKDBG_TEST_IMG="blkdebug:$TEST_DIR/blkdebug.conf:$TEST_IMG.base"
cat > "$TEST_DIR/blkdebug.conf" <<EOF
[inject-error]
event = "l2_update"
errno = "5"
immediately = "on"
once = "off"
EOF
# None of the following writes should trigger an L2 update, because the
# cluster already reads as zero, and we don't have to change allocation
$QEMU_IO -c "w -z -u 20M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "w -z 20M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "w -z 28M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
# success, all done
echo '*** done'
status=0