qemu-e2k/tests/qemu-iotests/225
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 vmdk backing file correlation
#
# Copyright (C) 2018 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=mreitz@redhat.com
seq=$(basename $0)
echo "QA output created by $seq"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
_rm_test_img "$TEST_IMG.not_base"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
. ./common.qemu
# This tests vmdk-specific low-level functionality
_supported_fmt vmdk
_supported_proto file
_supported_os Linux
_unsupported_imgopts "subformat=monolithicFlat" \
"subformat=twoGbMaxExtentFlat" \
"subformat=twoGbMaxExtentSparse"
TEST_IMG="$TEST_IMG.base" _make_test_img 1M
TEST_IMG="$TEST_IMG.not_base" _make_test_img 1M
_make_test_img -b "$TEST_IMG.base" -F $IMGFMT
make_opts()
{
node_name=$1
filename=$2
backing=$3
if [ -z "$backing" ]; then
backing="null"
else
backing="'$backing'"
fi
echo "{ 'node-name': '$node_name',
'driver': 'vmdk',
'file': {
'driver': 'file',
'filename': '$filename'
},
'backing': $backing }"
}
overlay_opts=$(make_opts overlay "$TEST_IMG" backing)
base_opts=$(make_opts backing "$TEST_IMG.base")
not_base_opts=$(make_opts backing "$TEST_IMG.not_base")
not_vmdk_opts="{ 'node-name': 'backing', 'driver': 'null-co' }"
echo
echo '=== Testing fitting VMDK backing image ==='
echo
qemu_comm_method=monitor \
_launch_qemu -blockdev "$base_opts" -blockdev "$overlay_opts"
# Should not return an error
_send_qemu_cmd $QEMU_HANDLE 'qemu-io overlay "read 0 512"' 'ops'
_cleanup_qemu
echo
echo '=== Testing unrelated VMDK backing image ==='
echo
qemu_comm_method=monitor \
_launch_qemu -blockdev "$not_base_opts" -blockdev "$overlay_opts"
# Should fail (gracefully)
_send_qemu_cmd $QEMU_HANDLE 'qemu-io overlay "read 0 512"' 'failed'
_cleanup_qemu
echo
echo '=== Testing non-VMDK backing image ==='
echo
# FIXME: This is the reason why we have to use two -blockdev
# invocations. You can only fully override the backing file options
# if you either specify a node reference (as done here) or the new
# options contain file.filename (which in this case they do not).
# In other cases, file.filename will be set to whatever the image
# header of the overlay contains (which we do not want). I consider
# this a FIXME because with -blockdev, you cannot specify "partial"
# options, so setting file.filename but leaving the rest as specified
# by the user does not make sense.
qemu_comm_method=monitor \
_launch_qemu -blockdev "$not_vmdk_opts" -blockdev "$overlay_opts"
# Should fail (gracefully)
_send_qemu_cmd $QEMU_HANDLE 'qemu-io overlay "read 0 512"' 'failed'
_cleanup_qemu
# success, all done
echo "*** done"
rm -f $seq.full
status=0