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253 lines
10 KiB
253 lines
10 KiB
From 2ee645a339e9ef9cd92620a8b784d18d512326be Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Thu, 25 Apr 2024 14:56:02 +0200
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Subject: [PATCH 4/4] block: Parse filenames only when explicitly requested
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RH-Author: Hana Czenczek <hczenczek@redhat.com>
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RH-MergeRequest: 1: CVE 2024-4467 (PRDSC)
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RH-Jira: RHEL-35611
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RH-CVE: CVE-2024-4467
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Eric Blake <eblake@redhat.com>
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RH-Commit: [4/4] f44c2941d4419e60f16dea3e9adca164e75aa78d
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When handling image filenames from legacy options such as -drive or from
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tools, these filenames are parsed for protocol prefixes, including for
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the json:{} pseudo-protocol.
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This behaviour is intended for filenames that come directly from the
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command line and for backing files, which may come from the image file
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itself. Higher level management tools generally take care to verify that
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untrusted images don't contain a bad (or any) backing file reference;
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'qemu-img info' is a suitable tool for this.
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However, for other files that can be referenced in images, such as
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qcow2 data files or VMDK extents, the string from the image file is
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usually not verified by management tools - and 'qemu-img info' wouldn't
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be suitable because in contrast to backing files, it already opens these
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other referenced files. So here the string should be interpreted as a
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literal local filename. More complex configurations need to be specified
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explicitly on the command line or in QMP.
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This patch changes bdrv_open_inherit() so that it only parses filenames
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if a new parameter parse_filename is true. It is set for the top level
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in bdrv_open(), for the file child and for the backing file child. All
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other callers pass false and disable filename parsing this way.
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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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Upstream: N/A, embargoed
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Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
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---
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block.c | 90 ++++++++++++++++++++++++++++++++++++---------------------
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1 file changed, 57 insertions(+), 33 deletions(-)
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diff --git a/block.c b/block.c
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index 468cf5e67d..50bdd197b7 100644
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--- a/block.c
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+++ b/block.c
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@@ -86,6 +86,7 @@ static BlockDriverState *bdrv_open_inherit(const char *filename,
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BlockDriverState *parent,
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const BdrvChildClass *child_class,
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BdrvChildRole child_role,
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+ bool parse_filename,
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Error **errp);
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static bool bdrv_recurse_has_child(BlockDriverState *bs,
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@@ -2058,7 +2059,8 @@ static void parse_json_protocol(QDict *options, const char **pfilename,
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* block driver has been specified explicitly.
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*/
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static int bdrv_fill_options(QDict **options, const char *filename,
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- int *flags, Error **errp)
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+ int *flags, bool allow_parse_filename,
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+ Error **errp)
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{
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const char *drvname;
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bool protocol = *flags & BDRV_O_PROTOCOL;
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@@ -2100,7 +2102,7 @@ static int bdrv_fill_options(QDict **options, const char *filename,
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if (protocol && filename) {
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if (!qdict_haskey(*options, "filename")) {
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qdict_put_str(*options, "filename", filename);
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- parse_filename = true;
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+ parse_filename = allow_parse_filename;
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} else {
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error_setg(errp, "Can't specify 'file' and 'filename' options at "
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"the same time");
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@@ -3663,7 +3665,8 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
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}
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backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
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- &child_of_bds, bdrv_backing_role(bs), errp);
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+ &child_of_bds, bdrv_backing_role(bs), true,
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+ errp);
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if (!backing_hd) {
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bs->open_flags |= BDRV_O_NO_BACKING;
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error_prepend(errp, "Could not open backing file: ");
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@@ -3697,7 +3700,8 @@ free_exit:
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static BlockDriverState *
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bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
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BlockDriverState *parent, const BdrvChildClass *child_class,
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- BdrvChildRole child_role, bool allow_none, Error **errp)
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+ BdrvChildRole child_role, bool allow_none,
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+ bool parse_filename, Error **errp)
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{
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BlockDriverState *bs = NULL;
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QDict *image_options;
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@@ -3728,7 +3732,8 @@ bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
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}
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bs = bdrv_open_inherit(filename, reference, image_options, 0,
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- parent, child_class, child_role, errp);
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+ parent, child_class, child_role, parse_filename,
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+ errp);
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if (!bs) {
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goto done;
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}
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@@ -3738,6 +3743,33 @@ done:
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return bs;
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}
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+static BdrvChild *bdrv_open_child_common(const char *filename,
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+ QDict *options, const char *bdref_key,
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+ BlockDriverState *parent,
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+ const BdrvChildClass *child_class,
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+ BdrvChildRole child_role,
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+ bool allow_none, bool parse_filename,
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+ Error **errp)
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+{
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+ BlockDriverState *bs;
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+ BdrvChild *child;
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+
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+ GLOBAL_STATE_CODE();
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+
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+ bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
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+ child_role, allow_none, parse_filename, errp);
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+ if (bs == NULL) {
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+ return NULL;
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+ }
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+
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+ bdrv_graph_wrlock();
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+ child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
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+ errp);
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+ bdrv_graph_wrunlock();
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+
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+ return child;
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+}
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+
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/*
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* Opens a disk image whose options are given as BlockdevRef in another block
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* device's options.
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@@ -3761,27 +3793,15 @@ BdrvChild *bdrv_open_child(const char *filename,
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BdrvChildRole child_role,
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bool allow_none, Error **errp)
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{
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- BlockDriverState *bs;
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- BdrvChild *child;
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-
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- GLOBAL_STATE_CODE();
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-
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- bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
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- child_role, allow_none, errp);
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- if (bs == NULL) {
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- return NULL;
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- }
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-
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- bdrv_graph_wrlock();
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- child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
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- errp);
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- bdrv_graph_wrunlock();
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-
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- return child;
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+ return bdrv_open_child_common(filename, options, bdref_key, parent,
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+ child_class, child_role, allow_none, false,
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+ errp);
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}
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/*
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- * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
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+ * This does mostly the same as bdrv_open_child(), but for opening the primary
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+ * child of a node. A notable difference from bdrv_open_child() is that it
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+ * enables filename parsing for protocol names (including json:).
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*
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* @parent can move to a different AioContext in this function.
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*/
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@@ -3796,8 +3816,8 @@ int bdrv_open_file_child(const char *filename,
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role = parent->drv->is_filter ?
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(BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
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- if (!bdrv_open_child(filename, options, bdref_key, parent,
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- &child_of_bds, role, false, errp))
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+ if (!bdrv_open_child_common(filename, options, bdref_key, parent,
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+ &child_of_bds, role, false, true, errp))
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{
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return -EINVAL;
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}
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@@ -3842,7 +3862,8 @@ BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
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}
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- bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
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+ bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, false,
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+ errp);
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obj = NULL;
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qobject_unref(obj);
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visit_free(v);
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@@ -3932,7 +3953,7 @@ static BlockDriverState * no_coroutine_fn
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bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
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int flags, BlockDriverState *parent,
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const BdrvChildClass *child_class, BdrvChildRole child_role,
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- Error **errp)
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+ bool parse_filename, Error **errp)
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{
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int ret;
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BlockBackend *file = NULL;
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@@ -3980,9 +4001,11 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
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}
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/* json: syntax counts as explicit options, as if in the QDict */
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- parse_json_protocol(options, &filename, &local_err);
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- if (local_err) {
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- goto fail;
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+ if (parse_filename) {
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+ parse_json_protocol(options, &filename, &local_err);
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+ if (local_err) {
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+ goto fail;
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+ }
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}
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bs->explicit_options = qdict_clone_shallow(options);
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@@ -4007,7 +4030,8 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
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parent->open_flags, parent->options);
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}
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- ret = bdrv_fill_options(&options, filename, &flags, &local_err);
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+ ret = bdrv_fill_options(&options, filename, &flags, parse_filename,
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+ &local_err);
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if (ret < 0) {
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goto fail;
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}
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@@ -4076,7 +4100,7 @@ bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
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file_bs = bdrv_open_child_bs(filename, options, "file", bs,
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&child_of_bds, BDRV_CHILD_IMAGE,
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- true, &local_err);
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+ true, true, &local_err);
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if (local_err) {
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goto fail;
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}
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@@ -4225,7 +4249,7 @@ BlockDriverState *bdrv_open(const char *filename, const char *reference,
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GLOBAL_STATE_CODE();
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return bdrv_open_inherit(filename, reference, options, flags, NULL,
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- NULL, 0, errp);
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+ NULL, 0, true, errp);
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}
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/* Return true if the NULL-terminated @list contains @str */
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--
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2.39.3
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