CHROMIUM: verity: do all hashing in dm-bht.c

drivers/md/dm-bht.c

Index: drivers/md/dm-bht.c
diff --git a/drivers/md/dm-bht.c b/drivers/md/dm-bht.c
index 35713de9bdd0b7f20dc8975443faa4f541087c36..726f210ab724178c21f82148ffa6ba385e3c2ddf 100644
--- a/drivers/md/dm-bht.c
+++ b/drivers/md/dm-bht.c
@@ -163,9 +163,6 @@ static inline u8 *dm_bht_get_node(struct dm_bht *bht,
 				  unsigned int block_index)
 {
 	unsigned int index = dm_bht_index_at_level(bht, depth, block_index);
-	struct dm_bht_level *level = dm_bht_get_level(bht, depth);
-
-	BUG_ON(index >= level->count);
 
 	return dm_bht_node(bht, entry, index % bht->node_count);
 }
@@ -590,32 +587,26 @@ static int dm_bht_update_hash(struct dm_bht *bht, u8 *known, u8 *computed)
 
 /* digest length and bht must be checked already */
 static int dm_bht_check_block(struct dm_bht *bht, unsigned int block_index,
-			      u8 *digest, int *entry_state)
+			      const void *buf, int *entry_state)

[Will Drewry, 2011/03/08 20:53:59]

nit: might prefer something more meaningful like "block" instead of just "buf".

 {
-	int depth;
-	unsigned int index;
-	struct dm_bht_entry *entry;
-
-	/* The leaves contain the block hashes */
-	depth = bht->depth - 1;
-
-	/* Index into the bottom level.  Each entry in this level contains
-	 * nodes whose hashes are the direct hashes of one block of data on
-	 * disk.
-	 */
-	index = block_index >> bht->node_count_shift;
-	entry = &bht->levels[depth].entries[index];
+	unsigned int depth = bht->depth;
+	struct dm_bht_entry *parent = dm_bht_get_entry(bht, depth - 1,
+						       block_index);
+	struct hash_desc *hash_desc = &bht->hash_desc[smp_processor_id()];
+	u8 digest[DM_BHT_MAX_DIGEST_SIZE];
+	u8 *node;
 
 	/* This call is only safe if all nodes along the path
 	 * are already populated (i.e. READY) via dm_bht_populate.
 	 */
-	BUG_ON(atomic_read(&entry->state) < DM_BHT_ENTRY_READY);
-
-	/* Index into the entry data */
-	index = (block_index % bht->node_count) * bht->digest_size;
-	if (memcmp(&entry->nodes[index], digest, bht->digest_size)) {
-		DMCRIT("digest mismatch for block %u", block_index);
-		dm_bht_log_mismatch(bht, &entry->nodes[index], digest);
+	*entry_state = atomic_read(&parent->state);
+	BUG_ON(*entry_state < DM_BHT_ENTRY_READY);
+
+	node = dm_bht_get_node(bht, parent, depth, block_index);
+	if (dm_bht_compute_hash(bht, hash_desc, virt_to_page(buf), digest) ||
+	    dm_bht_compare_hash(bht, digest, node)) {
+		DMERR("failed to verify entry's hash against parent "
+		      "(d=%u,bi=%u)", depth, block_index);
 		return DM_BHT_ENTRY_ERROR_MISMATCH;
 	}
 	return 0;
@@ -1069,17 +1060,11 @@ EXPORT_SYMBOL(dm_bht_populate);
  * should return similarly.
  */
 int dm_bht_verify_block(struct dm_bht *bht, unsigned int block_index,
-				u8 *digest, unsigned int digest_len)
+			const void *buf)

[Will Drewry, 2011/03/08 20:53:59]

Please update the comments.

 {
 	int unverified = 0;
 	int entry_state = 0;
 
-	/* TODO(wad) do we really need this? */
-	if (digest_len != bht->digest_size) {
-		DMERR("invalid digest_len passed to verify_block");
-		return -EINVAL;
-	}
-
 	/* Make sure that the root has been verified */
 	if (atomic_read(&bht->root_state) != DM_BHT_ENTRY_VERIFIED) {
 		unverified = dm_bht_verify_root(bht, dm_bht_compare_hash);
@@ -1090,7 +1075,7 @@ int dm_bht_verify_block(struct dm_bht *bht, unsigned int block_index,
 	}
 
 	/* Now check that the digest supplied matches the leaf hash */
-	unverified = dm_bht_check_block(bht, block_index, digest, &entry_state);
+	unverified = dm_bht_check_block(bht, block_index, buf, &entry_state);
 	if (unverified) {
 		DMERR_LIMIT("Block check failed for %u: %d", block_index,
 				unverified);