Add sign_virt_apex_test

This test re-signs the virt apex contents and then check if they are
signed with the new key. Note that this isn't an end-to-end test to
install re-signed apex and see if it works, but only checks avbtool
signable items are signed with the new key by comparing pubkey digest.
This will help to notice when adding a new signed item without modifying
sign_virt_apex though.

Bug: 193504286
Test: atest --host sign_virt_apex_test
Change-Id: I16098c49f41e14f571dca272310b81459d9803a8
diff --git a/apex/Android.bp b/apex/Android.bp
index 88487e4..3fbfd28 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -110,6 +110,41 @@
     ],
 }
 
+sh_test_host {
+    name: "sign_virt_apex_test",
+    src: "sign_virt_apex_test.sh",
+    test_config: "sign_virt_apex_test.xml",
+    data_bins: [
+        // deapexer
+        "deapexer",
+        "debugfs_static",
+
+        // sign_virt_apex
+        "avbtool",
+        "img2simg",
+        "lpmake",
+        "lpunpack",
+        "sign_virt_apex",
+        "simg2img",
+    ],
+    data_libs: [
+        "libbase",
+        "libc++",
+        "libcrypto_utils",
+        "libcrypto",
+        "libext4_utils",
+        "liblog",
+        "liblp",
+        "libsparse",
+        "libz",
+    ],
+    data: [
+        ":com.android.virt",
+        "test.com.android.virt.pem",
+    ],
+    test_suites: ["general-tests"],
+}
+
 // custom tool to replace bytes in a file
 python_binary_host {
     name: "replace_bytes",
diff --git a/apex/sign_virt_apex.py b/apex/sign_virt_apex.py
index b806a02..153b5dd 100644
--- a/apex/sign_virt_apex.py
+++ b/apex/sign_virt_apex.py
@@ -22,6 +22,8 @@
 - lpmake, lpunpack, simg2img, img2simg
 """
 import argparse
+import glob
+import hashlib
 import os
 import re
 import shutil
@@ -32,6 +34,8 @@
 
 def ParseArgs(argv):
     parser = argparse.ArgumentParser(description='Sign the Virt APEX')
+    parser.add_argument('--verify', action='store_true',
+                        help='Verify the Virt APEX')
     parser.add_argument(
         '-v', '--verbose',
         action='store_true',
@@ -336,10 +340,65 @@
                     'bootconfig': bootconfig_sign_key})
 
 
+def VerifyVirtApex(args):
+    # Generator to emit avbtool-signed items along with its pubkey digest.
+    # This supports lpmake-packed images as well.
+    def Recur(target_dir):
+        for file in glob.glob(os.path.join(target_dir, 'etc', '**', '*'), recursive=True):
+            cur_item = os.path.relpath(file, target_dir)
+
+            if not os.path.isfile(file):
+                continue
+
+            # avbpubkey
+            if cur_item == 'etc/microdroid_bootloader.avbpubkey':
+                with open(file, 'rb') as f:
+                    yield (cur_item, hashlib.sha1(f.read()).hexdigest())
+                continue
+
+            # avbtool signed
+            info, _ = AvbInfo(args, file)
+            if info:
+                yield (cur_item, info['Public key (sha1)'])
+                continue
+
+            # logical partition
+            with TempDirectory() as tmp_dir:
+                unsparsed = os.path.join(tmp_dir, os.path.basename(file))
+                _, rc = RunCommand(
+                    # exit with 255 if it's not sparsed
+                    args, ['simg2img', file, unsparsed], expected_return_values={0, 255})
+                if rc == 0:
+                    with TempDirectory() as unpack_dir:
+                        # exit with 64 if it's not a logical partition.
+                        _, rc = RunCommand(
+                            args, ['lpunpack', unsparsed, unpack_dir], expected_return_values={0, 64})
+                        if rc == 0:
+                            nested_items = list(Recur(unpack_dir))
+                            if len(nested_items) > 0:
+                                for (item, key) in nested_items:
+                                    yield ('%s!/%s' % (cur_item, item), key)
+                                continue
+    # Read pubkey digest
+    with TempDirectory() as tmp_dir:
+        pubkey_file = os.path.join(tmp_dir, 'avbpubkey')
+        ExtractAvbPubkey(args, args.key, pubkey_file)
+        with open(pubkey_file, 'rb') as f:
+            pubkey_digest = hashlib.sha1(f.read()).hexdigest()
+
+    # Check every avbtool-signed item against the input key
+    for (item, pubkey) in Recur(args.input_dir):
+        assert pubkey == pubkey_digest, '%s: key mismatch: %s != %s' % (
+            item, pubkey, pubkey_digest)
+
+
 def main(argv):
     try:
         args = ParseArgs(argv)
-        SignVirtApex(args)
+        if args.verify:
+            VerifyVirtApex(args)
+        else:
+            SignVirtApex(args)
     except Exception as e:
         print(e)
         sys.exit(1)
diff --git a/apex/sign_virt_apex_test.sh b/apex/sign_virt_apex_test.sh
new file mode 100644
index 0000000..640a3d4
--- /dev/null
+++ b/apex/sign_virt_apex_test.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+# Copyright (C) 2021 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+shopt -s extglob
+
+TMP_ROOT=$(mktemp -d -t sign_virt_apex-XXXXXXXX)
+TEST_DIR=$(dirname $0)
+
+# To access host tools
+PATH=$TEST_DIR:$PATH
+DEBUGFS=$TEST_DIR/debugfs_static
+
+deapexer --debugfs_path $DEBUGFS extract $TEST_DIR/com.android.virt.apex $TMP_ROOT
+
+if [ "$(ls -A $TMP_ROOT/etc/fs/)" ]; then
+  sign_virt_apex $TEST_DIR/test.com.android.virt.pem $TMP_ROOT
+  sign_virt_apex --verify $TEST_DIR/test.com.android.virt.pem $TMP_ROOT
+else
+  echo "No filesystem images. Skip."
+fi
+
diff --git a/apex/sign_virt_apex_test.xml b/apex/sign_virt_apex_test.xml
new file mode 100644
index 0000000..5ea84a1
--- /dev/null
+++ b/apex/sign_virt_apex_test.xml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<configuration description="Runs sign_virt_apex test">
+    <test class="com.android.tradefed.testtype.binary.ExecutableHostTest" >
+      <option name="binary" value="sign_virt_apex_test"/>
+    </test>
+</configuration>
diff --git a/apex/test.com.android.virt.pem b/apex/test.com.android.virt.pem
new file mode 100644
index 0000000..b0cfff4
--- /dev/null
+++ b/apex/test.com.android.virt.pem
@@ -0,0 +1,51 @@
+-----BEGIN RSA PRIVATE KEY-----
+MIIJKAIBAAKCAgEAw91a1/DFwSu1FbX92SxGshBGPvHW+4JpvVCw10rhx39pPynI
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+-----END RSA PRIVATE KEY-----