commit 4cf738204f091914a64167ef4b2dfe550f5b17fe
author Victor Hsieh <victorhsieh@google.com> Mon Apr 23 14:43:19 2018 -0700
committer Victor Hsieh <victorhsieh@google.com> Wed May 02 16:40:34 2018 +0000
tree 4de97a494d20f6471ca7fc40d864cc94bbb20062
parent f4c089dd905fab6bccd83285581ab9ee074d8a42

Avoid using 0 for fs-verity extension ID

Also:
 * Adjust size and order of some fields
 * Fix Merkle tree size calculation bug

Test: Verify fs-verity works with kernel patch
Bug: 67380979
Change-Id: I58f14cfe9630c1ff62ed64dbf333bb1c9bfe0fb1

core/java/android/util/apk/ApkVerityBuilder.java

diff --git a/core/java/android/util/apk/ApkVerityBuilder.java b/core/java/android/util/apk/ApkVerityBuilder.java
index f15e1a1..2dd0117 100644
--- a/core/java/android/util/apk/ApkVerityBuilder.java
+++ b/core/java/android/util/apk/ApkVerityBuilder.java
@@ -134,7 +134,7 @@
         assertSigningBlockAlignedAndHasFullPages(signatureInfo);
         long signingBlockSize =
                 signatureInfo.centralDirOffset - signatureInfo.apkSigningBlockOffset;
-        long dataSize = apk.length() - signingBlockSize - ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_SIZE;
+        long dataSize = apk.length() - signingBlockSize;
         int[] levelOffset = calculateVerityLevelOffset(dataSize);
 
         if (treeOutput != null) {
@@ -346,8 +346,8 @@
 
         buffer.putLong(fileSize);           // original file size
 
-        buffer.put((byte) 0);               // auth block offset, disabled here
-        buffer.put((byte) 2);               // extension count
+        buffer.put((byte) 2);               // authenticated extension count
+        buffer.put((byte) 0);               // unauthenticated extension count
         buffer.put(salt);                   // salt (8 bytes)
         skip(buffer, 22);                   // reserved
 
@@ -359,12 +359,6 @@
             long signingBlockSize, long eocdOffset) {
         // Snapshot of the FSVerity structs (subject to change once upstreamed).
         //
-        // struct fsverity_extension {
-        //   __le16 length;
-        //   u8 type;
-        //   u8 reserved[5];
-        // };
-        //
         // struct fsverity_extension_elide {
         //   __le64 offset;
         //   __le64 length;
@@ -382,10 +376,10 @@
             // struct fsverity_extension #1
             final int kSizeOfFsverityElidedExtension = 16;
 
-            buffer.putShort((short)  // total size of extension, padded to 64-bit alignment
-                    (kSizeOfFsverityExtensionHeader + kSizeOfFsverityElidedExtension));
-            buffer.put((byte) 0);    // ID of elide extension
-            skip(buffer, 5);         // reserved
+            // First field is total size of extension, padded to 64-bit alignment
+            buffer.putInt(kSizeOfFsverityExtensionHeader + kSizeOfFsverityElidedExtension);
+            buffer.putShort((short) 1);  // ID of elide extension
+            skip(buffer, 2);             // reserved
 
             // struct fsverity_extension_elide
             buffer.putLong(signingBlockOffset);
@@ -398,9 +392,9 @@
                     + 8 // offset size
                     + ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_SIZE;
 
-            buffer.putShort((short) kTotalSize);
-            buffer.put((byte) 1);    // ID of patch extension
-            skip(buffer, 5);         // reserved
+            buffer.putInt(kTotalSize);   // Total size of extension, padded to 64-bit alignment
+            buffer.putShort((short) 2);  // ID of patch extension
+            skip(buffer, 2);             // reserved
 
             // struct fsverity_extension_patch
             buffer.putLong(eocdOffset + ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_OFFSET);  // offset
@@ -412,7 +406,7 @@
             if (kPadding == kExtensionSizeAlignment) {
                 kPadding = 0;
             }
-            skip(buffer, kPadding);                              // padding
+            skip(buffer, kPadding);      // padding
         }
 
         buffer.flip();