[Qemu-devel] [PATCH v2] qcow2: add overlap check for bitmap directory

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---

If it appropriate for 2.12, let's push it. If not - then for 2.13.


v2: - squash 02 (indentation fix) to 01
    - drop comment from qcow2_check_metadata_overlap()
    - set @ign to QCOW2_OL_BITMAP_DIRECTORY for in-place case in
      bitmap_list_store. I don't think non-inplace case should be changed,
      as it don't touch active bitmap directory.

 block/qcow2.h          | 45 ++++++++++++++++++++++++---------------------
 block/qcow2-bitmap.c   |  7 ++++++-
 block/qcow2-refcount.c | 10 ++++++++++
 block/qcow2.c          | 22 ++++++++++++++--------
 4 files changed, 54 insertions(+), 30 deletions(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index 6f0ff15dd0..896ad08e5b 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -98,6 +98,7 @@
 #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_REFCOUNT_CACHE_SIZE "refcount-cache-size"
@@ -398,34 +399,36 @@ typedef enum QCow2ClusterType {
 } QCow2ClusterType;
 
 typedef enum QCow2MetadataOverlap {
-    QCOW2_OL_MAIN_HEADER_BITNR    = 0,
-    QCOW2_OL_ACTIVE_L1_BITNR      = 1,
-    QCOW2_OL_ACTIVE_L2_BITNR      = 2,
-    QCOW2_OL_REFCOUNT_TABLE_BITNR = 3,
-    QCOW2_OL_REFCOUNT_BLOCK_BITNR = 4,
-    QCOW2_OL_SNAPSHOT_TABLE_BITNR = 5,
-    QCOW2_OL_INACTIVE_L1_BITNR    = 6,
-    QCOW2_OL_INACTIVE_L2_BITNR    = 7,
-
-    QCOW2_OL_MAX_BITNR            = 8,
-
-    QCOW2_OL_NONE           = 0,
-    QCOW2_OL_MAIN_HEADER    = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
-    QCOW2_OL_ACTIVE_L1      = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
-    QCOW2_OL_ACTIVE_L2      = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
-    QCOW2_OL_REFCOUNT_TABLE = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
-    QCOW2_OL_REFCOUNT_BLOCK = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
-    QCOW2_OL_SNAPSHOT_TABLE = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
-    QCOW2_OL_INACTIVE_L1    = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
+    QCOW2_OL_MAIN_HEADER_BITNR      = 0,
+    QCOW2_OL_ACTIVE_L1_BITNR        = 1,
+    QCOW2_OL_ACTIVE_L2_BITNR        = 2,
+    QCOW2_OL_REFCOUNT_TABLE_BITNR   = 3,
+    QCOW2_OL_REFCOUNT_BLOCK_BITNR   = 4,
+    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              = 9,
+
+    QCOW2_OL_NONE             = 0,
+    QCOW2_OL_MAIN_HEADER      = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
+    QCOW2_OL_ACTIVE_L1        = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
+    QCOW2_OL_ACTIVE_L2        = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
+    QCOW2_OL_REFCOUNT_TABLE   = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
+    QCOW2_OL_REFCOUNT_BLOCK   = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
+    QCOW2_OL_SNAPSHOT_TABLE   = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
+    QCOW2_OL_INACTIVE_L1      = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
     /* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
      * reads. */
-    QCOW2_OL_INACTIVE_L2    = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
+    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 \
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index f45e46cfbd..fb750ba8d3 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -776,7 +776,12 @@ 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;
     }
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 3de1ab51ba..275a303cfa 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -2585,6 +2585,16 @@ 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;
 }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index 1914a940e5..23f36a67c7 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -655,6 +655,11 @@ static QemuOptsList qcow2_runtime_opts = {
             .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,
             .help = "Maximum combined metadata (L2 tables and refcount blocks) "
@@ -682,14 +687,15 @@ static QemuOptsList qcow2_runtime_opts = {
 };
 
 static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
-    [QCOW2_OL_MAIN_HEADER_BITNR]    = QCOW2_OPT_OVERLAP_MAIN_HEADER,
-    [QCOW2_OL_ACTIVE_L1_BITNR]      = QCOW2_OPT_OVERLAP_ACTIVE_L1,
-    [QCOW2_OL_ACTIVE_L2_BITNR]      = QCOW2_OPT_OVERLAP_ACTIVE_L2,
-    [QCOW2_OL_REFCOUNT_TABLE_BITNR] = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
-    [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
-    [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_MAIN_HEADER_BITNR]      = QCOW2_OPT_OVERLAP_MAIN_HEADER,
+    [QCOW2_OL_ACTIVE_L1_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L1,
+    [QCOW2_OL_ACTIVE_L2_BITNR]        = QCOW2_OPT_OVERLAP_ACTIVE_L2,
+    [QCOW2_OL_REFCOUNT_TABLE_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
+    [QCOW2_OL_REFCOUNT_BLOCK_BITNR]   = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
+    [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)
-- 
2.11.1