authfs: implement fs-verity Merkle tree verification

The fs-verity verification is compatible to the original format in Linux
kernel. The current verification only verifies a chunk of content
against the Merkle tree, without any signature check yet.

Bug: 171310075
Test: atest authfs_host_test_src_lib
Test: stress test with lots of possible input sizes

Change-Id: Icf2194aa5ebf282936d7b304bcc956d39f500b1a
11 files changed
tree: 86b52adc7bbb2fbbb9e2a052ccd00437c705aefa
  1. authfs/
  2. docs/
  3. .clang-format
  4. PREUPLOAD.cfg