d0b1ef237c
- block: Parse filenames only when explicitly requested (CVE-2024-4467) - block: introduce bdrv_open_file_child() helper - qcow2: Don't open data_file with BDRV_O_NO_IO (CVE-2024-4467) - qcow2: Do not reopen data_file in invalidate_cache Signed-off-by: Jiabo Feng <fengjiabo1@huawei.com>
109 lines
4.7 KiB
Diff
109 lines
4.7 KiB
Diff
From 89d32a19f14934bac61bb80955b8b29ac1ac9109 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 11 Apr 2024 15:06:01 +0200
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Subject: [PATCH] qcow2: Don't open data_file with BDRV_O_NO_IO (CVE-2024-4467)
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One use case for 'qemu-img info' is verifying that untrusted images
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don't reference an unwanted external file, be it as a backing file or an
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external data file. To make sure that calling 'qemu-img info' can't
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already have undesired side effects with a malicious image, just don't
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open the data file at all with BDRV_O_NO_IO. If nothing ever tries to do
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I/O, we don't need to have it open.
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This changes the output of iotests case 061, which used 'qemu-img info'
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to show that opening an image with an invalid data file fails. After
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this patch, it succeeds. Replace this part of the test with a qemu-io
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call, but keep the final 'qemu-img info' to show that the invalid data
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file is correctly displayed in the output.
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Fixes: CVE-2024-4467
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
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---
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block/qcow2.c | 17 ++++++++++++++++-
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tests/qemu-iotests/061 | 6 ++++--
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tests/qemu-iotests/061.out | 8 ++++++--
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3 files changed, 26 insertions(+), 5 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index 8e1b5ffe2d..c1992c571a 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1492,7 +1492,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
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goto fail;
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}
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- if (open_data_file) {
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+ if (open_data_file && (flags & BDRV_O_NO_IO)) {
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+ /*
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+ * Don't open the data file for 'qemu-img info' so that it can be used
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+ * to verify that an untrusted qcow2 image doesn't refer to external
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+ * files.
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+ *
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+ * Note: This still makes has_data_file() return true.
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+ */
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+ if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
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+ s->data_file = NULL;
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+ } else {
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+ s->data_file = bs->file;
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+ }
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+ qdict_extract_subqdict(options, NULL, "data-file.");
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+ qdict_del(options, "data-file");
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+ } else if (open_data_file) {
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/* Open external data file */
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s->data_file = bdrv_open_child(NULL, options, "data-file", bs,
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&child_file, true, &local_err);
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diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061
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index d7dbd7e2c7..ff8ca908d0 100755
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--- a/tests/qemu-iotests/061
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+++ b/tests/qemu-iotests/061
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@@ -268,12 +268,14 @@ $QEMU_IMG amend -o "data_file=foo" "$TEST_IMG"
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echo
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IMGOPTS="compat=1.1,data_file=$TEST_IMG.data" _make_test_img 64M
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$QEMU_IMG amend -o "data_file=foo" "$TEST_IMG"
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-_img_info --format-specific
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+$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt
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+$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io
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TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts
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echo
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$QEMU_IMG amend -o "data_file=" --image-opts "data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG"
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-_img_info --format-specific
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+$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt
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+$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io
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TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts
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echo
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diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
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index 1aa7d37ff9..8c6f1dbde3 100644
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--- a/tests/qemu-iotests/061.out
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+++ b/tests/qemu-iotests/061.out
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@@ -512,7 +512,9 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
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qemu-img: data-file can only be set for images that use an external data file
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IMGFMT.data
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-qemu-img: Could not open 'TEST_DIR/t.IMGFMT': Could not open 'foo': No such file or directory
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+qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not open 'foo': No such file or directory
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+read 4096/4096 bytes at offset 0
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+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 64 MiB (67108864 bytes)
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@@ -525,7 +527,9 @@ Format specific information:
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data file raw: false
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corrupt: false
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-qemu-img: Could not open 'TEST_DIR/t.IMGFMT': 'data-file' is required for this image
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+qemu-io: can't open device TEST_DIR/t.IMGFMT: 'data-file' is required for this image
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+read 4096/4096 bytes at offset 0
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+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 64 MiB (67108864 bytes)
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--
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2.41.0.windows.1
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