verity: remove short-circuiting of verify_path

dm-bht.c

  /*
  * Copyright (C) 2010 The Chromium OS Authors <chromium-os-dev@chromium.org>
  *
  * Device-Mapper block hash tree interface.
  * See Documentation/device-mapper/dm-bht.txt for details.
  *
  * This file is released under the GPL.
  */
 
 #include <asm/atomic.h>
@@ skipping 570 matching lines @@
         memcpy(known, computed, bht->digest_size);
 #ifdef CONFIG_DM_DEBUG
         dm_bht_bin_to_hex(computed, hex, bht->digest_size);
         DMDEBUG("updating with hash: %s", hex);
 #endif
         return 0;
 }
 
 /* Check the disk block against the leaf hash. */
 static int dm_bht_check_block(struct dm_bht *bht, unsigned int block_index,
-                              const void *block, int *entry_state)
+                              const void *block)
 {
         unsigned int depth = bht->depth;
         struct dm_bht_entry *parent = dm_bht_get_entry(bht, depth - 1,
                                                        block_index);
         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.
          */
-        *entry_state = atomic_read(&parent->state);
-        BUG_ON(*entry_state < DM_BHT_ENTRY_READY);
+        BUG_ON(atomic_read(&parent->state) < DM_BHT_ENTRY_READY);
 
         node = dm_bht_get_node(bht, parent, depth, block_index);
         if (dm_bht_compute_hash(bht, virt_to_page(block), 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;
 }
@@ skipping 436 matching lines @@
  * @block:      virtual address of the block data in memory
  *
  * Returns 0 on success, 1 on missing data, and a negative error
  * code on verification failure. All supporting functions called
  * should return similarly.
  */
 int dm_bht_verify_block(struct dm_bht *bht, unsigned int block_index,
                         const void *block)
 {
         int unverified = 0;
-        int entry_state = 0;
 
         /* 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);
                 if (unverified) {
                         DMERR_LIMIT("Failed to verify root: %d", unverified);
                         return unverified;
                 }
         }
 
         /* Now check that the digest supplied matches the leaf hash */
-        unverified = dm_bht_check_block(bht, block_index, block, &entry_state);
+        unverified = dm_bht_check_block(bht, block_index, block);
         if (unverified) {
                 DMERR_LIMIT("Block check failed for %u: %d", block_index,
                                 unverified);
                 return unverified;
         }
 
-        /* If the entry which contains the block hash is marked verified, then
-         * it means that its hash has been check with the parent.  In addition,
-         * since that is only possible via verify_path, it transitively means
-         * it is verified to the root of the tree. If the depth is 1, then it
-         * means the entry was verified during root verification.
-         */
-        if (entry_state == DM_BHT_ENTRY_VERIFIED || bht->depth == 1)
-                return unverified;
-
         /* Now check levels in between */
         unverified = dm_bht_verify_path(bht, block_index);
         if (unverified)
                 DMERR_LIMIT("Failed to verify intermediary nodes for block: %u (%d)",
                       block_index, unverified);
         return unverified;
 }
 EXPORT_SYMBOL(dm_bht_verify_block);
 
 /**
@@ skipping 152 matching lines @@
                 DMERR("no root digest exists to export");
                 if (available > 0)
                         *hexdigest = 0;
                 return -1;
         }
         dm_bht_bin_to_hex(bht->root_digest, hexdigest, bht->digest_size);
         return 0;
 }
 EXPORT_SYMBOL(dm_bht_root_hexdigest);