[PATCH 3.16 045/245] btrfs: tree-checker: Add checker for dir item

Ben Hutchings
2020-04-23T23:22:12Z

From: Qu Wenruo <wqu@suse.com>

commit ad7b0368f33cffe67fecd302028915926e50ef7e upstream.

Add checker for dir item, for key types DIR_ITEM, DIR_INDEX and
XATTR_ITEM.

This checker does comprehensive checks for:

1) dir_item header and its data size
Against item boundary and maximum name/xattr length.
This part is mostly the same as old verify_dir_item().

2) dir_type
Against maximum file types, and against key type.
Since XATTR key should only have FT_XATTR dir item, and normal dir
item type should not have XATTR key.

The check between key->type and dir_type is newly introduced by this
patch.

3) name hash
For XATTR and DIR_ITEM key, key->offset is name hash (crc32c).
Check the hash of the name against the key to ensure it's correct.

The name hash check is only found in btrfs-progs before this patch.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 4.4: BTRFS_MAX_XATTR_SIZE() takes a root instead of an
fs_info, and yields a value of type size_t instead of unsigned int]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/tree-checker.c | 141 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 141 insertions(+)

--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -30,6 +30,7 @@
#include "tree-checker.h"
#include "disk-io.h"
#include "compression.h"
+#include "hash.h"

#define CORRUPT(reason, eb, root, slot) \
btrfs_crit(root->fs_info, \
@@ -176,6 +177,141 @@ static int check_csum_item(struct btrfs_
}

/*
+ * Customized reported for dir_item, only important new info is key->objectid,
+ * which represents inode number
+ */
+__printf(4, 5)
+static void dir_item_err(const struct btrfs_root *root,
+ const struct extent_buffer *eb, int slot,
+ const char *fmt, ...)
+{
+ struct btrfs_key key;
+ struct va_format vaf;
+ va_list args;
+
+ btrfs_item_key_to_cpu(eb, &key, slot);
+ va_start(args, fmt);
+
+ vaf.fmt = fmt;
+ vaf.va = &args;
+
+ btrfs_crit(root->fs_info,
+ "corrupt %s: root=%llu block=%llu slot=%d ino=%llu, %pV",
+ btrfs_header_level(eb) == 0 ? "leaf" : "node", root->objectid,
+ btrfs_header_bytenr(eb), slot, key.objectid, &vaf);
+ va_end(args);
+}
+
+static int check_dir_item(struct btrfs_root *root,
+ struct extent_buffer *leaf,
+ struct btrfs_key *key, int slot)
+{
+ struct btrfs_dir_item *di;
+ u32 item_size = btrfs_item_size_nr(leaf, slot);
+ u32 cur = 0;
+
+ di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+ while (cur < item_size) {
+ char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+ u32 name_len;
+ u32 data_len;
+ u32 max_name_len;
+ u32 total_size;
+ u32 name_hash;
+ u8 dir_type;
+
+ /* header itself should not cross item boundary */
+ if (cur + sizeof(*di) > item_size) {
+ dir_item_err(root, leaf, slot,
+ "dir item header crosses item boundary, have %lu boundary %u",
+ cur + sizeof(*di), item_size);
+ return -EUCLEAN;
+ }
+
+ /* dir type check */
+ dir_type = btrfs_dir_type(leaf, di);
+ if (dir_type >= BTRFS_FT_MAX) {
+ dir_item_err(root, leaf, slot,
+ "invalid dir item type, have %u expect [0, %u)",
+ dir_type, BTRFS_FT_MAX);
+ return -EUCLEAN;
+ }
+
+ if (key->type == BTRFS_XATTR_ITEM_KEY &&
+ dir_type != BTRFS_FT_XATTR) {
+ dir_item_err(root, leaf, slot,
+ "invalid dir item type for XATTR key, have %u expect %u",
+ dir_type, BTRFS_FT_XATTR);
+ return -EUCLEAN;
+ }
+ if (dir_type == BTRFS_FT_XATTR &&
+ key->type != BTRFS_XATTR_ITEM_KEY) {
+ dir_item_err(root, leaf, slot,
+ "xattr dir type found for non-XATTR key");
+ return -EUCLEAN;
+ }
+ if (dir_type == BTRFS_FT_XATTR)
+ max_name_len = XATTR_NAME_MAX;
+ else
+ max_name_len = BTRFS_NAME_LEN;
+
+ /* Name/data length check */
+ name_len = btrfs_dir_name_len(leaf, di);
+ data_len = btrfs_dir_data_len(leaf, di);
+ if (name_len > max_name_len) {
+ dir_item_err(root, leaf, slot,
+ "dir item name len too long, have %u max %u",
+ name_len, max_name_len);
+ return -EUCLEAN;
+ }
+ if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root)) {
+ dir_item_err(root, leaf, slot,
+ "dir item name and data len too long, have %u max %zu",
+ name_len + data_len,
+ BTRFS_MAX_XATTR_SIZE(root));
+ return -EUCLEAN;
+ }
+
+ if (data_len && dir_type != BTRFS_FT_XATTR) {
+ dir_item_err(root, leaf, slot,
+ "dir item with invalid data len, have %u expect 0",
+ data_len);
+ return -EUCLEAN;
+ }
+
+ total_size = sizeof(*di) + name_len + data_len;
+
+ /* header and name/data should not cross item boundary */
+ if (cur + total_size > item_size) {
+ dir_item_err(root, leaf, slot,
+ "dir item data crosses item boundary, have %u boundary %u",
+ cur + total_size, item_size);
+ return -EUCLEAN;
+ }
+
+ /*
+ * Special check for XATTR/DIR_ITEM, as key->offset is name
+ * hash, should match its name
+ */
+ if (key->type == BTRFS_DIR_ITEM_KEY ||
+ key->type == BTRFS_XATTR_ITEM_KEY) {
+ read_extent_buffer(leaf, namebuf,
+ (unsigned long)(di + 1), name_len);
+ name_hash = btrfs_name_hash(namebuf, name_len);
+ if (key->offset != name_hash) {
+ dir_item_err(root, leaf, slot,
+ "name hash mismatch with key, have 0x%016x expect 0x%016llx",
+ name_hash, key->offset);
+ return -EUCLEAN;
+ }
+ }
+ cur += total_size;
+ di = (struct btrfs_dir_item *)((void *)di + total_size);
+ }
+ return 0;
+}
+
+/*
* Common point to switch the item-specific validation.
*/
static int check_leaf_item(struct btrfs_root *root,
@@ -191,6 +327,11 @@ static int check_leaf_item(struct btrfs_
case BTRFS_EXTENT_CSUM_KEY:
ret = check_csum_item(root, leaf, key, slot);
break;
+ case BTRFS_DIR_ITEM_KEY:
+ case BTRFS_DIR_INDEX_KEY:
+ case BTRFS_XATTR_ITEM_KEY:
+ ret = check_dir_item(root, leaf, key, slot);
+ break;
}
return ret;
}