block: Add option to use driver whitelist even in tools

Currently, the block driver whitelists are only applied for the system
emulator. All other binaries still give unrestricted access to all block
drivers. There are use cases where this made sense because the main
concern was avoiding customers running VMs on less optimised block
drivers and getting bad performance. Allowing the same image format e.g.
as a target for 'qemu-img convert' is not a problem then.

However, if the concern is the supportability of the driver in general,
either in full or when used read-write, not applying the list driver
whitelist in tools doesn't help - especially since qemu-nbd and
qemu-storage-daemon now give access to more or less the same operations
in block drivers as running a system emulator.

In order to address this, introduce a new configure option that enforces
the driver whitelist in all binaries.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210709164141.254097-1-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -6162,6 +6162,9 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
 
 void bdrv_init(void)
 {
+#ifdef CONFIG_BDRV_WHITELIST_TOOLS
+    use_bdrv_whitelist = 1;
+#endif
     module_call_init(MODULE_INIT_BLOCK);
 }
 

configure

@@ -243,6 +243,7 @@ cross_prefix=""
 audio_drv_list=""
 block_drv_rw_whitelist=""
 block_drv_ro_whitelist=""
+block_drv_whitelist_tools="no"
 host_cc="cc"
 audio_win_int=""
 libs_qga=""
@@ -1016,6 +1017,10 @@ for opt do
   ;;
   --block-drv-ro-whitelist=*) block_drv_ro_whitelist=$(echo "$optarg" | sed -e 's/,/ /g')
   ;;
+  --enable-block-drv-whitelist-in-tools) block_drv_whitelist_tools="yes"
+  ;;
+  --disable-block-drv-whitelist-in-tools) block_drv_whitelist_tools="no"
+  ;;
   --enable-debug-tcg) debug_tcg="yes"
   ;;
   --disable-debug-tcg) debug_tcg="no"
@@ -1800,10 +1805,12 @@ Advanced options (experts only):
   --block-drv-whitelist=L  Same as --block-drv-rw-whitelist=L
   --block-drv-rw-whitelist=L
                            set block driver read-write whitelist
-                           (affects only QEMU, not qemu-img)
+                           (by default affects only QEMU, not tools like qemu-img)
   --block-drv-ro-whitelist=L
                            set block driver read-only whitelist
-                           (affects only QEMU, not qemu-img)
+                           (by default affects only QEMU, not tools like qemu-img)
+  --enable-block-drv-whitelist-in-tools
+                           use block whitelist also in tools instead of only QEMU
   --enable-trace-backends=B Set trace backend
                            Available backends: $trace_backend_list
   --with-trace-file=NAME   Full PATH,NAME of file to store traces
@@ -4583,6 +4590,9 @@ if test "$audio_win_int" = "yes" ; then
 fi
 echo "CONFIG_BDRV_RW_WHITELIST=$block_drv_rw_whitelist" >> $config_host_mak
 echo "CONFIG_BDRV_RO_WHITELIST=$block_drv_ro_whitelist" >> $config_host_mak
+if test "$block_drv_whitelist_tools" = "yes" ; then
+  echo "CONFIG_BDRV_WHITELIST_TOOLS=y" >> $config_host_mak
+fi
 if test "$xfs" = "yes" ; then
   echo "CONFIG_XFS=y" >> $config_host_mak
 fi

meson.build

@@ -2996,6 +2996,7 @@ summary_info += {'coroutine pool':    config_host['CONFIG_COROUTINE_POOL'] == '1
 if have_block
   summary_info += {'Block whitelist (rw)': config_host['CONFIG_BDRV_RW_WHITELIST']}
   summary_info += {'Block whitelist (ro)': config_host['CONFIG_BDRV_RO_WHITELIST']}
+  summary_info += {'Use block whitelist in tools': config_host.has_key('CONFIG_BDRV_WHITELIST_TOOLS')}
   summary_info += {'VirtFS support':    have_virtfs}
   summary_info += {'build virtiofs daemon': have_virtiofsd}
   summary_info += {'Live block migration': config_host.has_key('CONFIG_LIVE_BLOCK_MIGRATION')}