qemu/tests/qemu-iotests/060

#!/bin/bash
#
# Test case for image corruption (overlapping data structures) in qcow2
#
# Copyright (C) 2013 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"

here="$PWD"
tmp=/tmp/$$
status=1	# failure is the default!

_cleanup()
{
	_cleanup_test_img
}
trap "_cleanup; exit \$status" 0 1 2 3 15

# get standard environment, filters and checks
. ./common.rc
. ./common.filter

# This tests qocw2-specific low-level functionality
_supported_fmt qcow2
_supported_proto file
_supported_os Linux

rt_offset=65536  # 0x10000 (XXX: just an assumption)
rb_offset=131072 # 0x20000 (XXX: just an assumption)
l1_offset=196608 # 0x30000 (XXX: just an assumption)
l2_offset=262144 # 0x40000 (XXX: just an assumption)
l2_offset_after_snapshot=524288 # 0x80000 (XXX: just an assumption)

IMGOPTS="compat=1.1"

OPEN_RW="open -o overlap-check=all $TEST_IMG"
# Overlap checks are done before write operations only, therefore opening an
# image read-only makes the overlap-check option irrelevant
OPEN_RO="open -r $TEST_IMG"

echo
echo "=== Testing L2 reference into L1 ==="
echo
_make_test_img 64M
# Link first L1 entry (first L2 table) onto itself
# (Note the MSb in the L1 entry is set, ensuring the refcount is one - else any
# later write will result in a COW operation, effectively ruining this attempt
# on image corruption)
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x03\x00\x00"
_check_test_img

# The corrupt bit should not be set anyway
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

# Try to write something, thereby forcing the corrupt bit to be set
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io

# The corrupt bit must now be set
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

# Try to open the image R/W (which should fail)
$QEMU_IO -c "$OPEN_RW" -c "read 0 512" 2>&1 | _filter_qemu_io \
                                            | _filter_testdir \
                                            | _filter_imgfmt

# Try to open it RO (which should succeed)
$QEMU_IO -c "$OPEN_RO" -c "read 0 512" | _filter_qemu_io

# We could now try to fix the image, but this would probably fail (how should an
# L2 table linked onto the L1 table be fixed?)

echo
echo "=== Testing cluster data reference into refcount block ==="
echo
_make_test_img 64M
# Allocate L2 table
truncate -s "$(($l2_offset+65536))" "$TEST_IMG"
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x04\x00\x00"
# Mark cluster as used
poke_file "$TEST_IMG" "$(($rb_offset+8))" "\x00\x01"
# Redirect new data cluster onto refcount block
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x02\x00\x00"
_check_test_img
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

# Try to fix it
_check_test_img -r all

# The corrupt bit should be cleared
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

# Look if it's really really fixed
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

echo
echo "=== Testing cluster data reference into inactive L2 table ==="
echo
_make_test_img 64M
$QEMU_IO -c "$OPEN_RW" -c "write -P 1 0 512" | _filter_qemu_io
$QEMU_IMG snapshot -c foo "$TEST_IMG"
$QEMU_IO -c "$OPEN_RW" -c "write -P 2 0 512" | _filter_qemu_io
# The inactive L2 table remains at its old offset
poke_file "$TEST_IMG" "$l2_offset_after_snapshot" \
                      "\x80\x00\x00\x00\x00\x04\x00\x00"
_check_test_img
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 3 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
_check_test_img -r all
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 4 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features

# Check data
$QEMU_IO -c "$OPEN_RO" -c "read -P 4 0 512" | _filter_qemu_io
$QEMU_IMG snapshot -a foo "$TEST_IMG"
_check_test_img
$QEMU_IO -c "$OPEN_RO" -c "read -P 1 0 512" | _filter_qemu_io

echo
echo "=== Testing overlap while COW is in flight ==="
echo
# compat=0.10 is required in order to make the following discard actually
# unallocate the sector rather than make it a zero sector - we want COW, after
# all.
IMGOPTS='compat=0.10' _make_test_img 1G
# Write two clusters, the second one enforces creation of an L2 table after
# the first data cluster.
$QEMU_IO -c 'write 0k 64k' -c 'write 512M 64k' "$TEST_IMG" | _filter_qemu_io
# Discard the first cluster. This cluster will soon enough be reallocated and
# used for COW.
$QEMU_IO -c 'discard 0k 64k' "$TEST_IMG" | _filter_qemu_io
# Now, corrupt the image by marking the second L2 table cluster as free.
poke_file "$TEST_IMG" '131084' "\x00\x00" # 0x2000c
# Start a write operation requiring COW on the image stopping it right before
# doing the read; then, trigger the corruption prevention by writing anything to
# any unallocated cluster, leading to an attempt to overwrite the second L2
# table. Finally, resume the COW write and see it fail (but not crash).
echo "open -o file.driver=blkdebug $TEST_IMG
break cow_read 0
aio_write 0k 1k
wait_break 0
write 64k 64k
resume 0" | $QEMU_IO | _filter_qemu_io

echo
echo "=== Testing unallocated image header ==="
echo
_make_test_img 64M
# Create L1/L2
$QEMU_IO -c "$OPEN_RW" -c "write 0 64k" | _filter_qemu_io
poke_file "$TEST_IMG" "$rb_offset" "\x00\x00"
$QEMU_IO -c "$OPEN_RW" -c "write 64k 64k" | _filter_qemu_io

# success, all done
echo "*** done"
rm -f $seq.full
status=0