Provide a field in the block group descriptor to store block bitmap checksum,
and some helper functions to calculate and verify it.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
lib/ext2fs/blknum.c | 11 +++++++++++
lib/ext2fs/csum.c | 15 +++++++++++++++
lib/ext2fs/ext2_fs.h | 3 ++-
lib/ext2fs/ext2fs.h | 1 +
lib/ext2fs/rw_bitmaps.c | 14 ++++++++++++++
lib/ext2fs/swapfs.c | 1 +
6 files changed, 44 insertions(+), 1 deletions(-)
diff --git a/lib/ext2fs/blknum.c b/lib/ext2fs/blknum.c
index 47d3fda..07b2cb3 100644
--- a/lib/ext2fs/blknum.c
+++ b/lib/ext2fs/blknum.c
@@ -183,6 +183,17 @@ static struct ext4_group_desc *ext4fs_group_desc(ext2_filsys fs,
}
/*
+ * Return the block bitmap checksum of a group
+ */
+blk64_t ext2fs_block_bitmap_checksum(ext2_filsys fs, dgrp_t group)
+{
+ struct ext4_group_desc *gdp;
+
+ gdp = ext4fs_group_desc(fs, fs->group_desc, group);
+ return gdp->bg_block_bitmap_csum;
+}
+
+/*
* Return the block bitmap block of a group
*/
blk64_t ext2fs_block_bitmap_loc(ext2_filsys fs, dgrp_t group)
diff --git a/lib/ext2fs/csum.c b/lib/ext2fs/csum.c
index 56b75da..f594c90 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -74,6 +74,21 @@ void ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group, char *bitmap,
gdp->bg_inode_bitmap_csum = ext2fs_bitmap_csum(fs, group, bitmap, size);
}
+void ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group, char *bitmap,
+ int size)
+{
+ struct ext4_group_desc *gdp = (struct ext4_group_desc *)
+ ext2fs_group_desc(fs, fs->group_desc, group);
+
+ if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT)
+ return;
+ if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return;
+
+ gdp->bg_block_bitmap_csum = ext2fs_bitmap_csum(fs, group, bitmap, size);
+}
+
__u32 ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
struct ext2_inode_large *inode)
{
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index 367bfdf..ec28fac 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -159,7 +159,8 @@ struct ext4_group_desc
__u16 bg_free_inodes_count; /* Free inodes count */
__u16 bg_used_dirs_count; /* Directories count */
__u16 bg_flags; /* EXT4_BG_flags (INODE_UNINIT, etc) */
- __u32 bg_reserved[2]; /* Likely block/inode bitmap checksum */
+ __u32 bg_reserved[1]; /* unclaimed */
+ __u32 bg_block_bitmap_csum; /* crc32c(uuid+group+bbitmap) */
__u16 bg_itable_unused; /* Unused inodes count */
__u16 bg_checksum; /* crc16(sb_uuid+group+desc) */
__u32 bg_block_bitmap_hi; /* Blocks bitmap block MSB */
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 0899e34..0cc3012 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -782,6 +782,7 @@ extern void ext2fs_free_blocks_count_add(struct ext2_super_block *super,
extern struct ext2_group_desc *ext2fs_group_desc(ext2_filsys fs,
struct opaque_ext2_group_desc *gdp,
dgrp_t group);
+extern blk64_t ext2fs_block_bitmap_csum(ext2_filsys fs, dgrp_t group);
extern blk64_t ext2fs_block_bitmap_loc(ext2_filsys fs, dgrp_t group);
extern void ext2fs_block_bitmap_loc_set(ext2_filsys fs, dgrp_t group,
blk64_t blk);
diff --git a/lib/ext2fs/rw_bitmaps.c b/lib/ext2fs/rw_bitmaps.c
index 57aba59..802ce9f 100644
--- a/lib/ext2fs/rw_bitmaps.c
+++ b/lib/ext2fs/rw_bitmaps.c
@@ -91,6 +91,10 @@ static errcode_t write_bitmaps(ext2_filsys fs, int do_inode, int do_block)
for (j = nbits; j < fs->blocksize * 8; j++)
ext2fs_set_bit(j, block_buf);
}
+
+ ext2fs_block_bitmap_csum_set(fs, i, block_buf, block_nbytes);
+ ext2fs_group_desc_csum_set(fs, i);
+
blk = ext2fs_block_bitmap_loc(fs, i);
if (blk) {
retval = io_channel_write_blk64(fs->io, blk, 1,
@@ -259,6 +263,16 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
retval = EXT2_ET_BLOCK_BITMAP_READ;
goto cleanup;
}
+ /* verify block bitmap checksum */
+ gdp = (struct ext4_group_desc *)
+ ext2fs_group_desc(fs, fs->group_desc,
+ i);
+ if (!(fs->flags &
+ EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
+ !ext2fs_bitmap_csum_verify(fs, i,
+ gdp->bg_block_bitmap_csum,
+ block_bitmap, block_nbytes))
+ return EXT2_ET_BLOCK_BITMAP_READ;
} else
memset(block_bitmap, 0, block_nbytes);
cnt = block_nbytes << 3;
diff --git a/lib/ext2fs/swapfs.c b/lib/ext2fs/swapfs.c
index 747e130..f657c47 100644
--- a/lib/ext2fs/swapfs.c
+++ b/lib/ext2fs/swapfs.c
@@ -126,6 +126,7 @@ void ext2fs_swap_group_desc2(ext2_filsys fs, struct ext2_group_desc *gdp)
ext2fs_swab16(gdp4->bg_used_dirs_count_hi);
gdp4->bg_itable_unused_hi = ext2fs_swab16(gdp4->bg_itable_unused_hi);
gdp4->bg_inode_bitmap_csum = ext2fs_swab32(gdp4->bg_inode_bitmap_csum);
+ gdp4->bg_block_bitmap_csum = ext2fs_swab32(gdp4->bg_block_bitmap_csum);
}
void ext2fs_swap_group_desc(struct ext2_group_desc *gdp)
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
