qemu-img: Require -F with -b backing image

Back in commit d9f059aa6c (qemu-img: Deprecate use of -b without -F),
we deprecated the ability to create a file with a backing image that
requires qemu to perform format probing.  Qemu can still probe older
files for backwards compatibility, but it is time to finish off the
ability to create such images, due to the potential security risk they
present.  Update a couple of iotests affected by the change.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210503213600.569128-3-eblake@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

6 files changed, 22 insertions, 37 deletions

diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
index ba7cb34ce8..f3677de9df 100755
--- a/tests/qemu-iotests/040
+++ b/tests/qemu-iotests/040
@@ -920,8 +920,8 @@ class TestCommitWithOverriddenBacking(iotests.QMPTestCase):
     def setUp(self):
         qemu_img('create', '-f', iotests.imgfmt, self.img_base_a, '1M')
         qemu_img('create', '-f', iotests.imgfmt, self.img_base_b, '1M')
-        qemu_img('create', '-f', iotests.imgfmt, '-b', self.img_base_a, \
-                 self.img_top)
+        qemu_img('create', '-f', iotests.imgfmt, '-b', self.img_base_a,
+                 '-F', iotests.imgfmt, self.img_top)
 
         self.vm = iotests.VM()
         self.vm.launch()
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 5cc02b24fc..db9f5dc540 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -1295,8 +1295,10 @@ class TestReplaces(iotests.QMPTestCase):
 class TestFilters(iotests.QMPTestCase):
     def setUp(self):
         qemu_img('create', '-f', iotests.imgfmt, backing_img, '1M')
-        qemu_img('create', '-f', iotests.imgfmt, '-b', backing_img, test_img)
-        qemu_img('create', '-f', iotests.imgfmt, '-b', backing_img, target_img)
+        qemu_img('create', '-f', iotests.imgfmt, '-b', backing_img,
+                 '-F', iotests.imgfmt, test_img)
+        qemu_img('create', '-f', iotests.imgfmt, '-b', backing_img,
+                 '-F', iotests.imgfmt, target_img)
 
         qemu_io('-c', 'write -P 1 0 512k', backing_img)
         qemu_io('-c', 'write -P 2 512k 512k', test_img)
diff --git a/tests/qemu-iotests/114 b/tests/qemu-iotests/114
index 43cb0bc6c3..de6fd327ee 100755
--- a/tests/qemu-iotests/114
+++ b/tests/qemu-iotests/114
@@ -44,16 +44,16 @@ _supported_os Linux
 # qcow2.py does not work too well with external data files
 _unsupported_imgopts data_file
 
-# Intentionally specify backing file without backing format; demonstrate
-# the difference in warning messages when backing file could be probed.
-# Note that only a non-raw probe result will affect the resulting image.
+# Older qemu-img could set up backing file without backing format; modern
+# qemu can't but we can use qcow2.py to simulate older files.
 truncate -s $((64 * 1024 * 1024)) "$TEST_IMG.orig"
-_make_test_img -b "$TEST_IMG.orig" 64M
+_make_test_img -b "$TEST_IMG.orig" -F raw 64M
+$PYTHON qcow2.py "$TEST_IMG" del-header-ext 0xE2792ACA
 
 TEST_IMG="$TEST_IMG.base" _make_test_img 64M
 $QEMU_IMG convert -O qcow2 -B "$TEST_IMG.orig" "$TEST_IMG.orig" "$TEST_IMG"
-_make_test_img -b "$TEST_IMG.base" 64M
-_make_test_img -u -b "$TEST_IMG.base" 64M
+_make_test_img -b "$TEST_IMG.base" -F $IMGFMT 64M
+_make_test_img -u -b "$TEST_IMG.base" -F $IMGFMT 64M
 
 # Set an invalid backing file format
 $PYTHON qcow2.py "$TEST_IMG" add-header-ext 0xE2792ACA "foo"
@@ -64,9 +64,9 @@ _img_info
 $QEMU_IO -c "open $TEST_IMG" -c "read 0 4k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -o backing.driver=$IMGFMT $TEST_IMG" -c "read 0 4k" | _filter_qemu_io
 
-# Rebase the image, to show that omitting backing format triggers a warning,
-# but probing now lets us use the backing file.
-$QEMU_IMG rebase -u -b "$TEST_IMG.base" "$TEST_IMG"
+# Rebase the image, to show that backing format is required.
+($QEMU_IMG rebase -u -b "$TEST_IMG.base" "$TEST_IMG" 2>&1 && echo "unexpected pass") | _filter_testdir
+$QEMU_IMG rebase -u -b "$TEST_IMG.base" -F $IMGFMT "$TEST_IMG"
 $QEMU_IO -c "open $TEST_IMG" -c "read 0 4k" 2>&1 | _filter_qemu_io | _filter_testdir
 
 # success, all done
diff --git a/tests/qemu-iotests/114.out b/tests/qemu-iotests/114.out
index 0a37d20c82..6d638da266 100644
--- a/tests/qemu-iotests/114.out
+++ b/tests/qemu-iotests/114.out
@@ -1,12 +1,9 @@
 QA output created by 114
-qemu-img: warning: Deprecated use of backing file without explicit backing format (detected format of raw)
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.orig
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.orig backing_fmt=raw
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
-qemu-img: warning: Deprecated use of backing file without explicit backing format
-qemu-img: warning: Deprecated use of backing file without explicit backing format (detected format of IMGFMT)
+qemu-img: Use of backing file requires explicit backing format
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
-qemu-img: warning: Deprecated use of unopened backing file without explicit backing format, use of this image requires potentially unsafe format probing
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
 virtual size: 64 MiB (67108864 bytes)
@@ -17,7 +14,7 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Could not open backing file: Unknow
 no file open, try 'help open'
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-qemu-img: warning: Deprecated use of backing file without explicit backing format, use of this image requires potentially unsafe format probing
+qemu-img: Could not change the backing file to 'TEST_DIR/t.qcow2.base': Invalid argument
 read 4096/4096 bytes at offset 0
 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 *** done
diff --git a/tests/qemu-iotests/301 b/tests/qemu-iotests/301
index 9f943cadbe..220de1043f 100755
--- a/tests/qemu-iotests/301
+++ b/tests/qemu-iotests/301
@@ -3,7 +3,7 @@
 #
 # Test qcow backing file warnings
 #
-# Copyright (C) 2020 Red Hat, Inc.
+# Copyright (C) 2020-2021 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
@@ -46,7 +46,6 @@ echo "== qcow backed by qcow =="
 
 TEST_IMG="$TEST_IMG.base" _make_test_img $size
 _make_test_img -b "$TEST_IMG.base" $size
-_img_info
 _make_test_img -b "$TEST_IMG.base" -F $IMGFMT $size
 _img_info
 
@@ -71,7 +70,6 @@ echo "== qcow backed by raw =="
 rm "$TEST_IMG.base"
 truncate --size=$size "$TEST_IMG.base"
 _make_test_img -b "$TEST_IMG.base" $size
-_img_info
 _make_test_img -b "$TEST_IMG.base" -F raw $size
 _img_info
 
diff --git a/tests/qemu-iotests/301.out b/tests/qemu-iotests/301.out
index 9004dad639..e280658191 100644
--- a/tests/qemu-iotests/301.out
+++ b/tests/qemu-iotests/301.out
@@ -2,13 +2,7 @@ QA output created by 301
 
 == qcow backed by qcow ==
 Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=33554432
-qemu-img: warning: Deprecated use of backing file without explicit backing format (detected format of IMGFMT)
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
-image: TEST_DIR/t.IMGFMT
-file format: IMGFMT
-virtual size: 32 MiB (33554432 bytes)
-cluster_size: 512
-backing file: TEST_DIR/t.IMGFMT.base
+qemu-img: TEST_DIR/t.IMGFMT: Backing file specified without backing format
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT
@@ -36,13 +30,7 @@ cluster_size: 512
 backing file: TEST_DIR/t.IMGFMT.base
 
 == qcow backed by raw ==
-qemu-img: warning: Deprecated use of backing file without explicit backing format (detected format of raw)
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
-image: TEST_DIR/t.IMGFMT
-file format: IMGFMT
-virtual size: 32 MiB (33554432 bytes)
-cluster_size: 512
-backing file: TEST_DIR/t.IMGFMT.base
+qemu-img: TEST_DIR/t.IMGFMT: Backing file specified without backing format
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
 image: TEST_DIR/t.IMGFMT
 file format: IMGFMT