Introduce post_process_mac_perms script.

usage: post_process_mac_perms [-h] -s SEINFO -d DIR -f POLICY

Tool to help modify an existing mac_permissions.xml with additional app certs
not already found in that policy. This becomes useful when a directory
containing apps is searched and the certs from those apps are added to the
policy not already explicitly listed.

optional arguments:
  -h, --help            show this help message and exit
  -s SEINFO, --seinfo SEINFO
                        seinfo tag for each generated stanza
  -d DIR, --dir DIR     Directory to search for apks
  -f POLICY, --file POLICY
                        mac_permissions.xml policy file

Change-Id: Ifbaca3b3120874a567d3f22eb487de1aa8bda796
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>

tools/post_process_mac_perms

+#!/usr/bin/env python
+#
+# Copyright (C) 2013 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.
+
+"""
+Tool to help modify an existing mac_permissions.xml with additional app
+certs not already found in that policy. This becomes useful when a directory
+containing apps is searched and the certs from those apps are added to the
+policy not already explicitly listed.
+"""
+
+import sys
+import os
+import argparse
+from base64 import b16encode, b64decode
+import fileinput
+import re
+import subprocess
+import zipfile
+
+PEM_CERT_RE = """-----BEGIN CERTIFICATE-----
+(.+?)
+-----END CERTIFICATE-----
+"""
+def collect_certs_for_app(filename):
+  app_certs = set()
+  with zipfile.ZipFile(filename, 'r') as apkzip:
+    for info in apkzip.infolist():
+      name = info.filename
+      if name.startswith('META-INF/') and name.endswith(('.DSA', '.RSA')):
+        cmd = ['openssl', 'pkcs7', '-inform', 'DER',
+               '-outform', 'PEM', '-print_certs']
+        p = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        pem_string, err = p.communicate(apkzip.read(name))
+        if err and err.strip():
+          raise RuntimeError('Problem running openssl on %s (%s)' % (filename, e))
+
+        # turn multiline base64 to single line base16
+        transform = lambda x: b16encode(b64decode(x.replace('\n', ''))).lower()
+        results = re.findall(PEM_CERT_RE, pem_string, re.DOTALL)
+        certs = [transform(i) for i in results]
+
+        app_certs.update(certs)
+
+  return app_certs
+
+def add_leftover_certs(args):
+  all_app_certs = set()
+  for dirpath, _, files in os.walk(args.dir):
+    transform = lambda x: os.path.join(dirpath, x)
+    condition = lambda x: x.endswith('.apk')
+    apps = [transform(i) for i in files if condition(i)]
+
+    # Collect certs for each app found
+    for app in apps:
+      app_certs = collect_certs_for_app(app)
+      all_app_certs.update(app_certs)
+
+  if all_app_certs:
+    policy_certs = set()
+    with open(args.policy, 'r') as f:
+      cert_pattern = 'signature="([a-fA-F0-9]+)"'
+      policy_certs = re.findall(cert_pattern, f.read())
+
+    cert_diff = all_app_certs.difference(policy_certs)
+
+    # Build xml stanzas
+    inner_tag = '<seinfo value="%s"/>' % args.seinfo
+    stanza = '<signer signature="%s">%s</signer>'
+    new_stanzas = [stanza % (cert, inner_tag) for cert in cert_diff]
+    mac_perms_string = ''.join(new_stanzas)
+    mac_perms_string += '</policy>'
+
+    # Inline replace with new policy stanzas
+    for line in fileinput.input(args.policy, inplace=True):
+      print line.replace('</policy>', mac_perms_string)
+
+def main(argv):
+  parser = argparse.ArgumentParser(description=__doc__)
+
+  parser.add_argument('-s', '--seinfo', dest='seinfo', required=True,
+                      help='seinfo tag for each generated stanza')
+  parser.add_argument('-d', '--dir', dest='dir', required=True,
+                      help='Directory to search for apks')
+  parser.add_argument('-f', '--file', dest='policy', required=True,
+                      help='mac_permissions.xml policy file')
+
+  parser.set_defaults(func=add_leftover_certs)
+  args = parser.parse_args()
+  args.func(args)
+
+if __name__ == '__main__':
+  main(sys.argv)