From patchwork Thu Jul 4 12:48:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 13723716 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1CA2C3271E for ; Thu, 4 Jul 2024 12:53:11 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sPLuP-0006S3-J3; Thu, 04 Jul 2024 08:49:57 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sPLuD-0005Zw-LN; Thu, 04 Jul 2024 08:49:47 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sPLu8-0006Wu-CG; Thu, 04 Jul 2024 08:49:45 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id CF8DA773A8; Thu, 4 Jul 2024 15:48:22 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 5A937FE78D; Thu, 4 Jul 2024 15:48:27 +0300 (MSK) Received: (nullmailer pid 1471807 invoked by uid 1000); Thu, 04 Jul 2024 12:48:26 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Kevin Wolf , Eric Blake , Stefan Hajnoczi , Hanna Czenczek , Michael Tokarev Subject: [Stable-7.2.13 14/17] qcow2: Don't open data_file with BDRV_O_NO_IO Date: Thu, 4 Jul 2024 15:48:21 +0300 Message-Id: <20240704124826.1471715-14-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Kevin Wolf One use case for 'qemu-img info' is verifying that untrusted images don't reference an unwanted external file, be it as a backing file or an external data file. To make sure that calling 'qemu-img info' can't already have undesired side effects with a malicious image, just don't open the data file at all with BDRV_O_NO_IO. If nothing ever tries to do I/O, we don't need to have it open. This changes the output of iotests case 061, which used 'qemu-img info' to show that opening an image with an invalid data file fails. After this patch, it succeeds. Replace this part of the test with a qemu-io call, but keep the final 'qemu-img info' to show that the invalid data file is correctly displayed in the output. Fixes: CVE-2024-4467 Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi Reviewed-by: Hanna Czenczek (cherry picked from commit bd385a5298d7062668e804d73944d52aec9549f1) Signed-off-by: Michael Tokarev diff --git a/block/qcow2.c b/block/qcow2.c index 4d6666d3ff..c810424feb 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1614,7 +1614,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, goto fail; } - if (open_data_file) { + if (open_data_file && (flags & BDRV_O_NO_IO)) { + /* + * Don't open the data file for 'qemu-img info' so that it can be used + * to verify that an untrusted qcow2 image doesn't refer to external + * files. + * + * Note: This still makes has_data_file() return true. + */ + if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { + s->data_file = NULL; + } else { + s->data_file = bs->file; + } + qdict_extract_subqdict(options, NULL, "data-file."); + qdict_del(options, "data-file"); + } else if (open_data_file) { /* Open external data file */ s->data_file = bdrv_open_child(NULL, options, "data-file", bs, &child_of_bds, BDRV_CHILD_DATA, diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061 index 509ad247cd..168a5831dd 100755 --- a/tests/qemu-iotests/061 +++ b/tests/qemu-iotests/061 @@ -326,12 +326,14 @@ $QEMU_IMG amend -o "data_file=foo" "$TEST_IMG" echo _make_test_img -o "compat=1.1,data_file=$TEST_IMG.data" 64M $QEMU_IMG amend -o "data_file=foo" "$TEST_IMG" -_img_info --format-specific +$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt +$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts echo $QEMU_IMG amend -o "data_file=" --image-opts "data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -_img_info --format-specific +$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt +$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts echo diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out index 139fc68177..24c33add7c 100644 --- a/tests/qemu-iotests/061.out +++ b/tests/qemu-iotests/061.out @@ -545,7 +545,9 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 qemu-img: data-file can only be set for images that use an external data file Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IMGFMT.data -qemu-img: Could not open 'TEST_DIR/t.IMGFMT': Could not open 'foo': No such file or directory +qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not open 'foo': No such file or directory +read 4096/4096 bytes at offset 0 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) image: TEST_DIR/t.IMGFMT file format: IMGFMT virtual size: 64 MiB (67108864 bytes) @@ -560,7 +562,9 @@ Format specific information: corrupt: false extended l2: false -qemu-img: Could not open 'TEST_DIR/t.IMGFMT': 'data-file' is required for this image +qemu-io: can't open device TEST_DIR/t.IMGFMT: 'data-file' is required for this image +read 4096/4096 bytes at offset 0 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) image: TEST_DIR/t.IMGFMT file format: IMGFMT virtual size: 64 MiB (67108864 bytes)