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 | 15 +++++++++++++++
lib/ext2fs/csum.c | 39 +++++++++++++++++++++++++++++++++++++++
lib/ext2fs/ext2_fs.h | 3 +++
lib/ext2fs/ext2fs.h | 6 ++++++
lib/ext2fs/rw_bitmaps.c | 16 ++++++++++++++++
5 files changed, 79 insertions(+), 0 deletions(-)
diff --git a/lib/ext2fs/blknum.c b/lib/ext2fs/blknum.c
index 30987fc..64f9b94 100644
--- a/lib/ext2fs/blknum.c
+++ b/lib/ext2fs/blknum.c
@@ -203,6 +203,21 @@ static struct ext4_group_desc *ext4fs_group_desc(ext2_filsys fs,
}
/*
+ * Return the block bitmap checksum of a group
+ */
+__u32 ext2fs_block_bitmap_checksum(ext2_filsys fs, dgrp_t group)
+{
+ struct ext4_group_desc *gdp;
+ __u32 csum;
+
+ gdp = ext4fs_group_desc(fs, fs->group_desc, group);
+ csum = gdp->bg_block_bitmap_csum_lo;
+ if (fs->super->s_desc_size < EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+ csum |= ((__u32)gdp->bg_block_bitmap_csum_hi << 16);
+ return 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 91b1892..524d0e5 100644
--- a/lib/ext2fs/csum.c
+++ b/lib/ext2fs/csum.c
@@ -83,6 +83,45 @@ errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
return 0;
}
+int ext2fs_block_bitmap_csum_verify(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);
+ __u32 provided, calculated;
+
+ if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 1;
+ provided = gdp->bg_block_bitmap_csum_lo;
+ calculated = ext2fs_bitmap_csum(fs, group, bitmap, size);
+ if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+ provided |= ((__u32)gdp->bg_block_bitmap_csum_hi << 16);
+ else
+ calculated &= 0xFFFF;
+
+ return provided == calculated;
+}
+
+errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
+ char *bitmap, int size)
+{
+ __u32 crc;
+ struct ext4_group_desc *gdp = (struct ext4_group_desc *)
+ ext2fs_group_desc(fs, fs->group_desc, group);
+
+ if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+ return 0;
+
+ crc = ext2fs_bitmap_csum(fs, group, bitmap, size);
+ gdp->bg_block_bitmap_csum_lo = crc & 0xFFFF;
+ if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
+ gdp->bg_block_bitmap_csum_hi = crc >> 16;
+
+ return 0;
+}
+
static errcode_t ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
struct ext2_inode_large *inode,
__u32 *crc)
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index e7f8bb4..cdfc4a8 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -194,6 +194,9 @@ struct ext4_group_desc
#define EXT4_BG_INODE_BITMAP_CSUM_HI_LOCATION \
(offsetof(struct ext4_group_desc, bg_inode_bitmap_csum_hi) + \
sizeof(__u16))
+#define EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION \
+ (offsetof(struct ext4_group_desc, bg_block_bitmap_csum_hi) + \
+ sizeof(__u16))
#define EXT2_BG_INODE_UNINIT 0x0001 /* Inode table/bitmap not initialized */
#define EXT2_BG_BLOCK_UNINIT 0x0002 /* Block bitmap not initialized */
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index d71181b..3b514a7 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -789,6 +789,7 @@ extern errcode_t ext2fs_get_block_bitmap_range2(ext2fs_block_bitmap bmap,
/* blknum.c */
extern __u32 ext2fs_inode_bitmap_checksum(ext2_filsys fs, dgrp_t group);
+extern __u32 ext2fs_block_bitmap_checksum(ext2_filsys fs, dgrp_t group);
extern dgrp_t ext2fs_group_of_blk2(ext2_filsys fs, blk64_t);
extern blk64_t ext2fs_group_first_block2(ext2_filsys fs, dgrp_t group);
extern blk64_t ext2fs_group_last_block2(ext2_filsys fs, dgrp_t group);
@@ -816,6 +817,7 @@ 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);
@@ -927,6 +929,10 @@ extern __u32 ext2fs_crc32c_be(__u32 crc, unsigned char const *p, size_t len);
extern __u32 ext2fs_crc32c_le(__u32 crc, unsigned char const *p, size_t len);
/* csum.c */
+extern errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
+ char *bitmap, int size);
+extern int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
+ char *bitmap, int size);
extern errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
char *bitmap, int size);
extern int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
diff --git a/lib/ext2fs/rw_bitmaps.c b/lib/ext2fs/rw_bitmaps.c
index a325fdb..df755cc 100644
--- a/lib/ext2fs/rw_bitmaps.c
+++ b/lib/ext2fs/rw_bitmaps.c
@@ -92,6 +92,13 @@ 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);
}
+
+ retval = ext2fs_block_bitmap_csum_set(fs, i, block_buf,
+ block_nbytes);
+ if (retval)
+ return retval;
+ 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,
@@ -273,6 +280,15 @@ 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_block_bitmap_csum_verify(fs, i,
+ block_bitmap, block_nbytes))
+ return EXT2_ET_BLOCK_BITMAP_READ;
} else
memset(block_bitmap, 0, block_nbytes);
cnt = block_nbytes << 3;
--
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