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From e04d52892c7fcd0e2ec70f77f3e5b934d45918c8 Mon Sep 17 00:00:00 2001
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From: Miroslav Rezanina <mrezanin@redhat.com>
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Date: Wed, 31 Jul 2013 09:56:17 +0200
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Subject: block: add block driver read only whitelist
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Message-id: <6873f36f1d3c26ad7b84bf2150c0a98afd6c5e72.1375208619.git.mrezanin@redhat.com>
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Patchwork-id: 52827
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O-Subject: [RHEL7 qemu-kvm PATCH 4.5/5] block: add block driver read only whitelist
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Bugzilla: 836675
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Michal Novotny <minovotn@redhat.com>
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From: Fam Zheng <famz@redhat.com>
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This is missing patch required for "VMDK Backports and Spec Update" serie.
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We may want to include a driver in the whitelist for read only tasks
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such as diagnosing or exporting guest data (with libguestfs as a good
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example). This patch introduces a readonly whitelist option, and for
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backward compatibility, the old configure option --block-drv-whitelist
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is now an alias to rw whitelist.
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Drivers in readonly list is only permitted to open file readonly, and
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returns -ENOTSUP for RW opening.
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E.g. To include vmdk readonly, and others read+write:
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    ./configure --target-list=x86_64-softmmu \
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                --block-drv-rw-whitelist=qcow2,raw,file,qed \
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                --block-drv-ro-whitelist=vmdk
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit b64ec4e4ade581d662753cdeb0d7e0e27aafbf81)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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diff --git a/block.c b/block.c
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index 3f87489..65c0b60 100644
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--- a/block.c
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+++ b/block.c
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@@ -328,28 +328,40 @@ BlockDriver *bdrv_find_format(const char *format_name)
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     return NULL;
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 }
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-static int bdrv_is_whitelisted(BlockDriver *drv)
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+static int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
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 {
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-    static const char *whitelist[] = {
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-        CONFIG_BDRV_WHITELIST
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+    static const char *whitelist_rw[] = {
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+        CONFIG_BDRV_RW_WHITELIST
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+    };
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+    static const char *whitelist_ro[] = {
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+        CONFIG_BDRV_RO_WHITELIST
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     };
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     const char **p;
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-    if (!whitelist[0])
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+    if (!whitelist_rw[0] && !whitelist_ro[0]) {
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         return 1;               /* no whitelist, anything goes */
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+    }
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-    for (p = whitelist; *p; p++) {
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+    for (p = whitelist_rw; *p; p++) {
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         if (!strcmp(drv->format_name, *p)) {
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             return 1;
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         }
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     }
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+    if (read_only) {
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+        for (p = whitelist_ro; *p; p++) {
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+            if (!strcmp(drv->format_name, *p)) {
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+                return 1;
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+            }
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+        }
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+    }
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     return 0;
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 }
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-BlockDriver *bdrv_find_whitelisted_format(const char *format_name)
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+BlockDriver *bdrv_find_whitelisted_format(const char *format_name,
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+                                          bool read_only)
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 {
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     BlockDriver *drv = bdrv_find_format(format_name);
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-    return drv && bdrv_is_whitelisted(drv) ? drv : NULL;
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+    return drv && bdrv_is_whitelisted(drv, read_only) ? drv : NULL;
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 }
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 typedef struct CreateCo {
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@@ -684,10 +696,6 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
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     trace_bdrv_open_common(bs, filename ?: "", flags, drv->format_name);
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-    if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
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-        return -ENOTSUP;
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-    }
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-
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     /* bdrv_open() with directly using a protocol as drv. This layer is already
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      * opened, so assign it to bs (while file becomes a closed BlockDriverState)
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      * and return immediately. */
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@@ -698,9 +706,15 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
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     bs->open_flags = flags;
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     bs->buffer_alignment = 512;
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+    open_flags = bdrv_open_flags(bs, flags);
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+    bs->read_only = !(open_flags & BDRV_O_RDWR);
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+
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+    if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
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+        return -ENOTSUP;
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+    }
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     assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
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-    if ((flags & BDRV_O_RDWR) && (flags & BDRV_O_COPY_ON_READ)) {
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+    if (!bs->read_only && (flags & BDRV_O_COPY_ON_READ)) {
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         bdrv_enable_copy_on_read(bs);
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     }
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@@ -714,9 +728,6 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
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     bs->opaque = g_malloc0(drv->instance_size);
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     bs->enable_write_cache = !!(flags & BDRV_O_CACHE_WB);
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-    open_flags = bdrv_open_flags(bs, flags);
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-
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-    bs->read_only = !(open_flags & BDRV_O_RDWR);
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     /* Open the image, either directly or using a protocol */
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     if (drv->bdrv_file_open) {
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@@ -801,7 +812,7 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
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     /* Find the right block driver */
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     drvname = qdict_get_try_str(options, "driver");
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     if (drvname) {
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-        drv = bdrv_find_whitelisted_format(drvname);
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+        drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
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         qdict_del(options, "driver");
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     } else if (filename) {
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         drv = bdrv_find_protocol(filename);
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diff --git a/blockdev.c b/blockdev.c
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index 625d041..6500c47 100644
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--- a/blockdev.c
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+++ b/blockdev.c
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@@ -477,7 +477,7 @@ DriveInfo *drive_init(QemuOpts *all_opts, BlockInterfaceType block_default_type)
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             error_printf("\n");
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             return NULL;
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         }
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-        drv = bdrv_find_whitelisted_format(buf);
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+        drv = bdrv_find_whitelisted_format(buf, ro);
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         if (!drv) {
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             error_report("'%s' invalid format", buf);
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             return NULL;
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@@ -1024,7 +1024,7 @@ void qmp_change_blockdev(const char *device, const char *filename,
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     }
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     if (format) {
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-        drv = bdrv_find_whitelisted_format(format);
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+        drv = bdrv_find_whitelisted_format(format, bs->read_only);
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         if (!drv) {
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             error_set(errp, QERR_INVALID_BLOCK_FORMAT, format);
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             return;
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diff --git a/configure b/configure
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index eb74510..a71e8a1 100755
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--- a/configure
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+++ b/configure
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@@ -123,7 +123,8 @@ interp_prefix="/usr/gnemul/qemu-%M"
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 static="no"
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 cross_prefix=""
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 audio_drv_list=""
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-block_drv_whitelist=""
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+block_drv_rw_whitelist=""
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+block_drv_ro_whitelist=""
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 host_cc="cc"
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 libs_softmmu=""
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 libs_tools=""
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@@ -708,7 +709,9 @@ for opt do
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   ;;
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   --audio-drv-list=*) audio_drv_list="$optarg"
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   ;;
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-  --block-drv-whitelist=*) block_drv_whitelist=`echo "$optarg" | sed -e 's/,/ /g'`
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+  --block-drv-rw-whitelist=*|--block-drv-whitelist=*) block_drv_rw_whitelist=`echo "$optarg" | sed -e 's/,/ /g'`
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+  ;;
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+  --block-drv-ro-whitelist=*) block_drv_ro_whitelist=`echo "$optarg" | sed -e 's/,/ /g'`
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   ;;
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   --enable-debug-tcg) debug_tcg="yes"
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   ;;
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@@ -1105,7 +1108,12 @@ echo "  --disable-cocoa          disable Cocoa (Mac OS X only)"
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 echo "  --enable-cocoa           enable Cocoa (default on Mac OS X)"
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 echo "  --audio-drv-list=LIST    set audio drivers list:"
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 echo "                           Available drivers: $audio_possible_drivers"
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-echo "  --block-drv-whitelist=L  set block driver whitelist"
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+echo "  --block-drv-whitelist=L  Same as --block-drv-rw-whitelist=L"
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+echo "  --block-drv-rw-whitelist=L"
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+echo "                           set block driver read-write whitelist"
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+echo "                           (affects only QEMU, not qemu-img)"
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+echo "  --block-drv-ro-whitelist=L"
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+echo "                           set block driver read-only whitelist"
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 echo "                           (affects only QEMU, not qemu-img)"
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 echo "  --enable-mixemu          enable mixer emulation"
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 echo "  --disable-xen            disable xen backend driver support"
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@@ -3525,7 +3533,8 @@ echo "curses support    $curses"
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 echo "curl support      $curl"
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 echo "mingw32 support   $mingw32"
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 echo "Audio drivers     $audio_drv_list"
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-echo "Block whitelist   $block_drv_whitelist"
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+echo "Block whitelist (rw) $block_drv_rw_whitelist"
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+echo "Block whitelist (ro) $block_drv_ro_whitelist"
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 echo "Mixer emulation   $mixemu"
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 echo "VirtFS support    $virtfs"
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 echo "VNC support       $vnc"
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@@ -3704,7 +3713,8 @@ fi
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 if test "$audio_win_int" = "yes" ; then
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   echo "CONFIG_AUDIO_WIN_INT=y" >> $config_host_mak
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 fi
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-echo "CONFIG_BDRV_WHITELIST=$block_drv_whitelist" >> $config_host_mak
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+echo "CONFIG_BDRV_RW_WHITELIST=$block_drv_rw_whitelist" >> $config_host_mak
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+echo "CONFIG_BDRV_RO_WHITELIST=$block_drv_ro_whitelist" >> $config_host_mak
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 if test "$mixemu" = "yes" ; then
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   echo "CONFIG_MIXEMU=y" >> $config_host_mak
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 fi
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diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
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index 0ac65d4..247f32f 100644
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--- a/hw/block/xen_disk.c
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+++ b/hw/block/xen_disk.c
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@@ -780,11 +780,13 @@ static int blk_connect(struct XenDevice *xendev)
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 {
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     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
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     int pers, index, qflags;
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+    bool readonly = true;
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     /* read-only ? */
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     qflags = BDRV_O_CACHE_WB | BDRV_O_NATIVE_AIO;
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     if (strcmp(blkdev->mode, "w") == 0) {
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         qflags |= BDRV_O_RDWR;
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+        readonly = false;
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     }
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     /* init qemu block driver */
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@@ -795,8 +797,10 @@ static int blk_connect(struct XenDevice *xendev)
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         xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
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         blkdev->bs = bdrv_new(blkdev->dev);
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         if (blkdev->bs) {
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-            if (bdrv_open(blkdev->bs, blkdev->filename, NULL, qflags,
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-                        bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
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+            BlockDriver *drv = bdrv_find_whitelisted_format(blkdev->fileproto,
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+                                                           readonly);
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+            if (bdrv_open(blkdev->bs,
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+                          blkdev->filename, NULL, qflags, drv) != 0) {
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                 bdrv_delete(blkdev->bs);
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                 blkdev->bs = NULL;
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             }
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diff --git a/include/block/block.h b/include/block/block.h
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index 1251c5c..5604418 100644
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--- a/include/block/block.h
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+++ b/include/block/block.h
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@@ -124,7 +124,8 @@ void bdrv_init(void);
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 void bdrv_init_with_whitelist(void);
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 BlockDriver *bdrv_find_protocol(const char *filename);
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 BlockDriver *bdrv_find_format(const char *format_name);
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-BlockDriver *bdrv_find_whitelisted_format(const char *format_name);
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+BlockDriver *bdrv_find_whitelisted_format(const char *format_name,
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+                                          bool readonly);
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 int bdrv_create(BlockDriver *drv, const char* filename,
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     QEMUOptionParameter *options);
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 int bdrv_create_file(const char* filename, QEMUOptionParameter *options);
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diff --git a/scripts/create_config b/scripts/create_config
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index c471e8c..258513a 100755
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--- a/scripts/create_config
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+++ b/scripts/create_config
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@@ -34,8 +34,15 @@ case $line in
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     done
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     echo ""
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     ;;
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- CONFIG_BDRV_WHITELIST=*)
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-    echo "#define CONFIG_BDRV_WHITELIST \\"
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+ CONFIG_BDRV_RW_WHITELIST=*)
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+    echo "#define CONFIG_BDRV_RW_WHITELIST\\"
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+    for drv in ${line#*=}; do
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+      echo "    \"${drv}\",\\"
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+    done
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+    echo "    NULL"
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+    ;;
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+ CONFIG_BDRV_RO_WHITELIST=*)
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+    echo "#define CONFIG_BDRV_RO_WHITELIST\\"
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     for drv in ${line#*=}; do
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       echo "    \"${drv}\",\\"
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     done