qemu-e2k/tests/qemu-iotests/043
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 that qemu-img info --backing-chain detects infinite loops
#
# Copyright (C) 2012 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=stefanha@redhat.com
seq=`basename $0`
echo "QA output created by $seq"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
for img in "$TEST_IMG".[123].base; do
_rm_test_img "$img"
done
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
# Any format supporting backing files
_supported_fmt qcow2 qed
_supported_proto file
size=128M
_make_test_img $size
$QEMU_IMG rebase -u -b "$TEST_IMG" -F $IMGFMT "$TEST_IMG"
echo
echo "== backing file references self =="
_img_info --backing-chain
_make_test_img $size
mv "$TEST_IMG" "$TEST_IMG.base"
_make_test_img -b "$TEST_IMG.base" -F $IMGFMT $size
$QEMU_IMG rebase -u -b "$TEST_IMG" -F $IMGFMT "$TEST_IMG.base"
echo
echo "== parent references self =="
_img_info --backing-chain
_make_test_img $size
mv "$TEST_IMG" "$TEST_IMG.1.base"
_make_test_img -b "$TEST_IMG.1.base" -F $IMGFMT $size
mv "$TEST_IMG" "$TEST_IMG.2.base"
_make_test_img -b "$TEST_IMG.2.base" -F $IMGFMT $size
mv "$TEST_IMG" "$TEST_IMG.3.base"
_make_test_img -b "$TEST_IMG.3.base" -F $IMGFMT $size
$QEMU_IMG rebase -u -b "$TEST_IMG.2.base" -F $IMGFMT "$TEST_IMG.1.base"
echo
echo "== ancestor references another ancestor =="
_img_info --backing-chain
_make_test_img $size
mv "$TEST_IMG" "$TEST_IMG.1.base"
_make_test_img -b "$TEST_IMG.1.base" -F $IMGFMT $size
mv "$TEST_IMG" "$TEST_IMG.2.base"
_make_test_img -b "$TEST_IMG.2.base" -F $IMGFMT $size
echo
echo "== finite chain of length 3 (human) =="
# Exclude backing format, since qed differs from qcow2 on what gets stored
_img_info --backing-chain | grep -v '^backing file format:'
echo
echo "== finite chain of length 3 (json) =="
_img_info --backing-chain --output=json | grep -v 'backing-filename-format'
# success, all done
echo "*** done"
rm -f $seq.full
status=0