qcow2: add overlap check for bitmap directory

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20180705151515.779173-1-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/qcow2-bitmap.c

@@ -775,7 +775,12 @@ static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
         }
     }
 
-    ret = qcow2_pre_write_overlap_check(bs, 0, dir_offset, dir_size);
+    /* Actually, even in in-place case ignoring QCOW2_OL_BITMAP_DIRECTORY is not
+     * necessary, because we drop QCOW2_AUTOCLEAR_BITMAPS when updating bitmap
+     * directory in-place (actually, turn-off the extension), which is checked
+     * in qcow2_check_metadata_overlap() */
+    ret = qcow2_pre_write_overlap_check(
+            bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size);
     if (ret < 0) {
         goto fail;
     }

block/qcow2-refcount.c

@@ -2705,6 +2705,16 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
         }
     }
 
+    if ((chk & QCOW2_OL_BITMAP_DIRECTORY) &&
+        (s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS))
+    {
+        if (overlaps_with(s->bitmap_directory_offset,
+                          s->bitmap_directory_size))
+        {
+            return QCOW2_OL_BITMAP_DIRECTORY;
+        }
+    }
+
     return 0;
 }
 

block/qcow2.c

@@ -679,6 +679,11 @@ static QemuOptsList qcow2_runtime_opts = {
             .type = QEMU_OPT_BOOL,
             .help = "Check for unintended writes into an inactive L2 table",
         },
+        {
+            .name = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
+            .type = QEMU_OPT_BOOL,
+            .help = "Check for unintended writes into the bitmap directory",
+        },
         {
             .name = QCOW2_OPT_CACHE_SIZE,
             .type = QEMU_OPT_SIZE,
@@ -720,6 +725,7 @@ static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
     [QCOW2_OL_SNAPSHOT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
     [QCOW2_OL_INACTIVE_L1_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L1,
     [QCOW2_OL_INACTIVE_L2_BITNR]      = QCOW2_OPT_OVERLAP_INACTIVE_L2,
+    [QCOW2_OL_BITMAP_DIRECTORY_BITNR] = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
 };
 
 static void cache_clean_timer_cb(void *opaque)

block/qcow2.h

@@ -94,6 +94,7 @@
 #define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
 #define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
+#define QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY "overlap-check.bitmap-directory"
 #define QCOW2_OPT_CACHE_SIZE "cache-size"
 #define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
 #define QCOW2_OPT_L2_CACHE_ENTRY_SIZE "l2-cache-entry-size"
@@ -408,8 +409,9 @@ typedef enum QCow2MetadataOverlap {
     QCOW2_OL_SNAPSHOT_TABLE_BITNR   = 5,
     QCOW2_OL_INACTIVE_L1_BITNR      = 6,
     QCOW2_OL_INACTIVE_L2_BITNR      = 7,
+    QCOW2_OL_BITMAP_DIRECTORY_BITNR = 8,
 
-    QCOW2_OL_MAX_BITNR            = 8,
+    QCOW2_OL_MAX_BITNR              = 9,
 
     QCOW2_OL_NONE             = 0,
     QCOW2_OL_MAIN_HEADER      = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
@@ -422,12 +424,13 @@ typedef enum QCow2MetadataOverlap {
     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
      * reads. */
     QCOW2_OL_INACTIVE_L2      = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
+    QCOW2_OL_BITMAP_DIRECTORY = (1 << QCOW2_OL_BITMAP_DIRECTORY_BITNR),
 } QCow2MetadataOverlap;
 
 /* Perform all overlap checks which can be done in constant time */
 #define QCOW2_OL_CONSTANT \
     (QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_REFCOUNT_TABLE | \
-     QCOW2_OL_SNAPSHOT_TABLE)
+     QCOW2_OL_SNAPSHOT_TABLE | QCOW2_OL_BITMAP_DIRECTORY)
 
 /* Perform all overlap checks which don't require disk access */
 #define QCOW2_OL_CACHED \

qapi/block-core.json

@@ -2696,6 +2696,8 @@
 # @template: Specifies a template mode which can be adjusted using the other
 #            flags, defaults to 'cached'
 #
+# @bitmap-directory: since 3.0
+#
 # Since: 2.9
 ##
 { 'struct': 'Qcow2OverlapCheckFlags',
@@ -2707,7 +2709,8 @@
             '*refcount-block':   'bool',
             '*snapshot-table':   'bool',
             '*inactive-l1':      'bool',
-            '*inactive-l2':    'bool' } }
+            '*inactive-l2':      'bool',
+            '*bitmap-directory': 'bool' } }
 
 ##
 # @Qcow2OverlapChecks: