btrfs: Add sanity check for EXTENT_DATA when reading out leaf

Add extra checks for item with EXTENT_DATA type.  This checks the
following thing:

0) Key offset
   All key offsets must be aligned to sectorsize.
   Inline extent must have 0 for key offset.

1) Item size
   Uncompressed inline file extent size must match item size.
   (Compressed inline file extent has no information about its on-disk size.)
   Regular/preallocated file extent size must be a fixed value.

2) Every member of regular file extent item
   Including alignment for bytenr and offset, possible value for
   compression/encryption/type.

3) Type/compression/encode must be one of the valid values.

This should be the most comprehensive and strict check in the context
of btrfs_item for EXTENT_DATA.

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ switch to BTRFS_FILE_EXTENT_TYPES, similar to what
  BTRFS_COMPRESS_TYPES does ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d1770b3..b863d41 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -549,6 +549,100 @@ static int check_tree_block_fsid(struct btrfs_fs_info *fs_info,
                   btrfs_header_level(eb) == 0 ? "leaf" : "node",       \
                   reason, btrfs_header_bytenr(eb), root->objectid, slot)
 
+static int check_extent_data_item(struct btrfs_root *root,
+                                 struct extent_buffer *leaf,
+                                 struct btrfs_key *key, int slot)
+{
+       struct btrfs_file_extent_item *fi;
+       u32 sectorsize = root->fs_info->sectorsize;
+       u32 item_size = btrfs_item_size_nr(leaf, slot);
+
+       if (!IS_ALIGNED(key->offset, sectorsize)) {
+               CORRUPT("unaligned key offset for file extent",
+                       leaf, root, slot);
+               return -EUCLEAN;
+       }
+
+       fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
+
+       if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
+               CORRUPT("invalid file extent type", leaf, root, slot);
+               return -EUCLEAN;
+       }
+
+       /*
+        * Support for new compression/encrption must introduce incompat flag,
+        * and must be caught in open_ctree().
+        */
+       if (btrfs_file_extent_compression(leaf, fi) > BTRFS_COMPRESS_TYPES) {
+               CORRUPT("invalid file extent compression", leaf, root, slot);
+               return -EUCLEAN;
+       }
+       if (btrfs_file_extent_encryption(leaf, fi)) {
+               CORRUPT("invalid file extent encryption", leaf, root, slot);
+               return -EUCLEAN;
+       }
+       if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
+               /* Inline extent must have 0 as key offset */
+               if (key->offset) {
+                       CORRUPT("inline extent has non-zero key offset",
+                               leaf, root, slot);
+                       return -EUCLEAN;
+               }
+
+               /* Compressed inline extent has no on-disk size, skip it */
+               if (btrfs_file_extent_compression(leaf, fi) !=
+                   BTRFS_COMPRESS_NONE)
+                       return 0;
+
+               /* Uncompressed inline extent size must match item size */
+               if (item_size != BTRFS_FILE_EXTENT_INLINE_DATA_START +
+                   btrfs_file_extent_ram_bytes(leaf, fi)) {
+                       CORRUPT("plaintext inline extent has invalid size",
+                               leaf, root, slot);
+                       return -EUCLEAN;
+               }
+               return 0;
+       }
+
+       /* Regular or preallocated extent has fixed item size */
+       if (item_size != sizeof(*fi)) {
+               CORRUPT(
+               "regluar or preallocated extent data item size is invalid",
+                       leaf, root, slot);
+               return -EUCLEAN;
+       }
+       if (!IS_ALIGNED(btrfs_file_extent_ram_bytes(leaf, fi), sectorsize) ||
+           !IS_ALIGNED(btrfs_file_extent_disk_bytenr(leaf, fi), sectorsize) ||
+           !IS_ALIGNED(btrfs_file_extent_disk_num_bytes(leaf, fi), sectorsize) ||
+           !IS_ALIGNED(btrfs_file_extent_offset(leaf, fi), sectorsize) ||
+           !IS_ALIGNED(btrfs_file_extent_num_bytes(leaf, fi), sectorsize)) {
+               CORRUPT(
+               "regular or preallocated extent data item has unaligned value",
+                       leaf, root, slot);
+               return -EUCLEAN;
+       }
+
+       return 0;
+}
+
+/*
+ * Common point to switch the item-specific validation.
+ */
+static int check_leaf_item(struct btrfs_root *root,
+                          struct extent_buffer *leaf,
+                          struct btrfs_key *key, int slot)
+{
+       int ret = 0;
+
+       switch (key->type) {
+       case BTRFS_EXTENT_DATA_KEY:
+               ret = check_extent_data_item(root, leaf, key, slot);
+               break;
+       }
+       return ret;
+}
+
 static noinline int check_leaf(struct btrfs_root *root,
                               struct extent_buffer *leaf)
 {
@@ -605,9 +699,13 @@ static noinline int check_leaf(struct btrfs_root *root,
         * 1) key order
         * 2) item offset and size
         *    No overlap, no hole, all inside the leaf.
+        * 3) item content
+        *    If possible, do comprehensive sanity check.
+        *    NOTE: All checks must only rely on the item data itself.
         */
        for (slot = 0; slot < nritems; slot++) {
                u32 item_end_expected;
+               int ret;
 
                btrfs_item_key_to_cpu(leaf, &key, slot);
 
@@ -650,6 +748,11 @@ static noinline int check_leaf(struct btrfs_root *root,
                        return -EUCLEAN;
                }
 
+               /* Check if the item size and content meet other criteria */
+               ret = check_leaf_item(root, leaf, &key, slot);
+               if (ret < 0)
+                       return ret;
+
                prev_key.objectid = key.objectid;
                prev_key.type = key.type;
                prev_key.offset = key.offset;

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 10689e1..3142645 100644 (file)
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -732,6 +732,7 @@ struct btrfs_balance_item {
 #define BTRFS_FILE_EXTENT_INLINE 0
 #define BTRFS_FILE_EXTENT_REG 1
 #define BTRFS_FILE_EXTENT_PREALLOC 2
+#define BTRFS_FILE_EXTENT_TYPES        2
 
 struct btrfs_file_extent_item {
        /*