diff options
| author | Aditya Prakash Srivastava <aditya.ansh182@gmail.com> | 2026-07-16 07:41:50 +0000 |
|---|---|---|
| committer | Viacheslav Dubeyko <slava@dubeyko.com> | 2026-07-20 12:17:57 -0700 |
| commit | b4160f6325a84c0b04d32be32f928ca647b21b6e (patch) | |
| tree | 8ca720beb6d7e4da63fde69008adab2fb212dbd5 /include/linux | |
| parent | fdbb95ff89b24a65dad510c7d7100e7548c09c98 (diff) | |
hfs: port HFS+ b-tree bitmap corruption check
In HFS+ filesystems, during b-tree open (hfs_btree_open()), the code
verifies that the allocation map bit for the tree header (node 0) is
set. If not, it indicates a corrupted map record/bitmap and mounts
the volume as read-only (SB_RDONLY) to prevent further damage.
HFS filesystems share the same b-tree structure but currently lack
this corruption detection check.
Port this check to HFS, aligning its implementation with HFS+ to
maintain consistent b-tree logic across both filesystems:
1. Define struct hfs_bmap_ctx, and define HFS_TREE_HEAD and the relevant
map record indices in include/linux/hfs_common.h.
2. Port the necessary offset and length validation helpers to
fs/hfs/btree.h as static inline functions with robust null pointer
checks.
3. Implement static hfs_bmap_get_map_page() in fs/hfs/btree.c.
4. Implement static hfs_bmap_test_bit() in fs/hfs/btree.c to inspect
the B-tree bitmap using the get_map_page helper.
5. Implement static hfs_bmap_clear_bit() in fs/hfs/btree.c.
6. Rewrite hfs_bmap_alloc() in fs/hfs/btree.c to use the unified
hfs_bmap_get_map_page() helper, eliminating redundant page and offset
calculation code.
7. Refactor hfs_bmap_free() in fs/hfs/btree.c to use the new
hfs_bmap_clear_bit() helper.
8. In hfs_btree_open(), retrieve the header node via hfs_bnode_find(),
test its allocation bit with hfs_bmap_test_bit(), and release it
using hfs_bnode_put().
Suggested-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/all/6a36101b.be22b350.2a3e9.0001.GAE@google.com/T/#r446d0fed2a2900bd805534bbcb799d86619ae2ea
Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260716074150.1660-1-aditya.ansh182@gmail.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/hfs_common.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/include/linux/hfs_common.h b/include/linux/hfs_common.h index 45fb4c9ff9f5..d6a615e74b26 100644 --- a/include/linux/hfs_common.h +++ b/include/linux/hfs_common.h @@ -510,14 +510,21 @@ struct hfs_btree_header_rec { b-tree but not in extents b-tree (hfsplus). */ +/* HFS BTree misc info */ +#define HFS_TREE_HEAD 0 +#define HFS_BTREE_HDR_MAP_REC_INDEX 2 /* Map (bitmap) record in Header node */ +#define HFS_BTREE_MAP_NODE_REC_INDEX 0 /* Map record in Map Node */ + /* HFS+ BTree misc info */ -#define HFSPLUS_TREE_HEAD 0 +#define HFSPLUS_TREE_HEAD HFS_TREE_HEAD #define HFSPLUS_NODE_MXSZ 32768 #define HFSPLUS_NODE_MINSZ 512 #define HFSPLUS_ATTR_TREE_NODE_SIZE 8192 #define HFSPLUS_BTREE_HDR_NODE_RECS_COUNT 3 -#define HFSPLUS_BTREE_HDR_MAP_REC_INDEX 2 /* Map (bitmap) record in Header node */ -#define HFSPLUS_BTREE_MAP_NODE_REC_INDEX 0 /* Map record in Map Node */ +/* Map (bitmap) record in Header node */ +#define HFSPLUS_BTREE_HDR_MAP_REC_INDEX HFS_BTREE_HDR_MAP_REC_INDEX +/* Map record in Map Node */ +#define HFSPLUS_BTREE_MAP_NODE_REC_INDEX HFS_BTREE_MAP_NODE_REC_INDEX #define HFSPLUS_BTREE_HDR_USER_BYTES 128 #define HFSPLUS_BTREE_MAP_NODE_RECS_COUNT 2 #define HFSPLUS_BTREE_MAP_NODE_RESERVED_BYTES 2 |