[PATCH v6 1/4] ntfs: reject non-resident records for resident-only attributes

[DaeMyung Kang <charsyam@gmail.com>]

The shared lookup-time attribute validator rejects non-resident
$FILE_NAME and $VOLUME_NAME records because their formats require
resident values and callers handle returned records as resident
attributes. Other resident-only attribute types still pass through the
generic non-resident mapping-pairs checks.

That leaves real resident/non-resident union confusion paths. Inode load
looks up $STANDARD_INFORMATION and then reads data.resident.value_offset
without checking a->non_resident. ntfs_inode_sync_standard_information()
does the same when updating the standard information value.
ntfs_write_volume_flags() also looks up $VOLUME_INFORMATION and reads
data.resident.value_offset directly. $INDEX_ROOT callers in dir.c and
index.c depend on the same lookup contract before consuming the resident
index root value.

Reject non-resident records for all resident-only attribute types in the
shared validator. Keep the existing $FILE_NAME and $VOLUME_NAME behavior,
but factor it through a helper and extend it to
$STANDARD_INFORMATION, $OBJECT_ID, $VOLUME_INFORMATION, $INDEX_ROOT, and
$EA_INFORMATION. For $OBJECT_ID and $EA_INFORMATION this is contract
hardening for resident-only formats; this patch only rejects the
non-resident form and does not add new resident value validation for
those types.

Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
---
 fs/ntfs/attrib.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 5e1ad1cd0118..1254fbe7666e 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -596,6 +596,22 @@ static u32 ntfs_resident_attr_min_value_length(const __le32 type)
 	}
 }
 
+static bool ntfs_attr_type_is_resident_only(const __le32 type)
+{
+	switch (type) {
+	case AT_STANDARD_INFORMATION:
+	case AT_FILE_NAME:
+	case AT_OBJECT_ID:
+	case AT_VOLUME_NAME:
+	case AT_VOLUME_INFORMATION:
+	case AT_INDEX_ROOT:
+	case AT_EA_INFORMATION:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static bool ntfs_file_name_attr_value_is_valid(const u8 *value, const u32 value_length)
 {
 	const struct file_name_attr *fn;
@@ -666,7 +682,7 @@ static bool ntfs_attr_value_is_valid(struct ntfs_volume *vol,
 	u32 min_len;
 
 	if (a->non_resident) {
-		if (a->type == AT_FILE_NAME || a->type == AT_VOLUME_NAME)
+		if (ntfs_attr_type_is_resident_only(a->type))
 			goto corrupt;
 		if (!ntfs_non_resident_attr_value_is_valid(a))
 			goto corrupt;
-- 
2.43.0