From patchwork Tue Jul 2 16:39:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 13720072 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 AAD1DC3DA40 for ; Tue, 2 Jul 2024 16:42:12 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sOgYI-0005py-Gv; Tue, 02 Jul 2024 12:40:22 -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 1sOgYD-0005ne-1c for qemu-devel@nongnu.org; Tue, 02 Jul 2024 12:40:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sOgY3-0008Oz-7M for qemu-devel@nongnu.org; Tue, 02 Jul 2024 12:40:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1719938406; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0sszMcQ9HKCsFtPXabnsiH9GPa27av1dB9YF+5jtJfU=; b=Ih5wc/zW+EAenX67Iz2LWfyo09EM2qTqAM94Glxkbk0o0sBEUdW5jXqLDvJilt8lVnhqk6 48zk2O6fq+DSfOWvfUrpS5pBR4nfbJbta0h1AD+Ebbkp/znqMsvk/H4tL5gKAnsQbcmKDk Bf1irtPXmfDYavI4MV8V2RoNy+2XHuo= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-681-94qxzfOONoK38G1qoMJnfA-1; Tue, 02 Jul 2024 12:40:03 -0400 X-MC-Unique: 94qxzfOONoK38G1qoMJnfA-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2099D196CDE1; Tue, 2 Jul 2024 16:40:02 +0000 (UTC) Received: from merkur.redhat.com (unknown [10.39.192.206]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id D3E4819560AE; Tue, 2 Jul 2024 16:39:58 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, richard.henderson@linaro.org, hreitz@redhat.com, eblake@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org Subject: [PULL 1/4] qcow2: Don't open data_file with BDRV_O_NO_IO Date: Tue, 2 Jul 2024 18:39:40 +0200 Message-ID: <20240702163943.276618-2-kwolf@redhat.com> In-Reply-To: <20240702163943.276618-1-kwolf@redhat.com> References: <20240702163943.276618-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 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 --- block/qcow2.c | 17 ++++++++++++++++- tests/qemu-iotests/061 | 6 ++++-- tests/qemu-iotests/061.out | 8 ++++++-- 3 files changed, 26 insertions(+), 5 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 10883a2494..70b19730a3 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1636,7 +1636,22 @@ qcow2_do_open(BlockDriverState *bs, QDict *options, int flags, 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 */ bdrv_graph_co_rdunlock(); s->data_file = bdrv_co_open_child(NULL, options, "data-file", bs, diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061 index 53c7d428e3..b71ac097d1 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)