auth: Keep audit log of all generated delegation tokens.

appengine/auth_service/delegation.py

Index: appengine/auth_service/delegation.py
diff --git a/appengine/auth_service/delegation.py b/appengine/auth_service/delegation.py
index c2cb4d3a76e64f459d3a9257c75fc2f4614e5517..98e061644f1ac774188c036866c712711558a6a1 100644
--- a/appengine/auth_service/delegation.py
+++ b/appengine/auth_service/delegation.py
@@ -7,10 +7,13 @@
 import logging
 import webapp2
 
+from google.appengine.ext import ndb
+
 from components import auth
 from components import utils
 
 from components.auth import delegation
+from components.auth import ipaddr
 from components.auth.proto import delegation_pb2
 
 from proto import config_pb2
@@ -78,7 +81,7 @@ class CreateDelegationTokenHandler(auth.ApiHandler):
       raise auth.AuthorizationError(
           'This API call must not be used with active delegation token')
 
-    # Convert request body to proto (with validation).
+    # Convert request body to proto (with validation). Verify IP format.
     try:
       subtoken = subtoken_from_jsonish(self.parse_body())
     except (TypeError, ValueError) as exc:
@@ -98,7 +101,10 @@ class CreateDelegationTokenHandler(auth.ApiHandler):
       subtoken.services[:] = get_default_allowed_services(user_id)
 
     # Check ACL (raises auth.AuthorizationError on errors).
-    check_can_create_token(user_id, subtoken)
+    rule = check_can_create_token(user_id, subtoken)
+
+    # Register the token in the datastore, generate its ID.
+    subtoken.subtoken_id = register_subtoken(subtoken, rule, auth.get_peer_ip())
 
     # Create and sign the token.
     try:
@@ -183,6 +189,9 @@ def subtoken_from_jsonish(d):
   return msg
 
 
+################################################################################
+
+
 # Fallback rule returned if nothing else matches.
 DEFAULT_RULE = config_pb2.DelegationConfig.Rule(
     user_id=['*'],
@@ -243,6 +252,9 @@ def check_can_create_token(user_id, subtoken):
     user_id: identity string of a current caller.
     subtoken: instance of delegation_pb2.Subtoken describing root token.
 
+  Returns:
+    config_pb2.DelegationConfig.Rule that allows the operation.
+
   Raises:
     auth.AuthorizationError if such token is not allowed for the caller.
   """
@@ -255,13 +267,13 @@ def check_can_create_token(user_id, subtoken):
 
   # Just delegating one's own identity (not impersonating someone else)? Allow.
   if subtoken.issuer_id == user_id:
-    return
+    return rule
 
   # Verify it's OK to impersonate a given user.
   impersonated = auth.Identity.from_bytes(subtoken.issuer_id)
   for principal_set in rule.allowed_to_impersonate:
     if is_identity_in_principal_set(impersonated, principal_set):
-      return
+      return rule
 
   raise auth.AuthorizationError(
       '"%s" is not allowed to impersonate "%s" on %s' %
@@ -277,3 +289,62 @@ def get_default_allowed_services(user_id):
   rule = get_delegation_rule(user_id, ['*'])
   return rule.target_service
 
+
+################################################################################
+
+
+class AuthDelegationSubtoken(ndb.Model):
+  """Represents a delegation subtoken.
+
+  Used to track what tokens are issued. Root entity. ID is autogenerated.
+  """
+  # Serialized delegation_pb2.Subtoken proto.
+  subtoken = ndb.BlobProperty()
+  # Serialized config_pb2.DelegationConfig.Rule that allowed this token.
+  rule = ndb.BlobProperty()
+  # IP address the minting request came from.
+  caller_ip = ndb.StringProperty()
+  # Version of the auth_service that created the subtoken.
+  auth_service_version = ndb.StringProperty()
+
+  # Fields below are extracted from 'subtoken', for indexing purposes.
+
+  # Whose authority the token conveys.
+  issuer_id = ndb.StringProperty()
+  # When the token was created.
+  creation_time = ndb.DateTimeProperty()
+  # List of services that accept the token (or ['*'] if all).
+  services = ndb.StringProperty(repeated=True)
+  # Who initiated the minting request if it is an impersonation token.
+  impersonator_id = ndb.StringProperty()
+
+
+def register_subtoken(subtoken, rule, caller_ip):
+  """Creates new AuthDelegationSubtoken entity in the datastore, returns its ID.
+
+  Args:
+    subtoken: delegation_pb2.Subtoken describing the token.
+    rule: config_pb2.DelegationConfig.Rule that allows the operation
+    caller_ip: ipaddr.IP of the caller.
+
+  Returns:
+    int64 with ID of the new entity.
+  """
+  entity = AuthDelegationSubtoken(
+      subtoken=subtoken.SerializeToString(),
+      rule=rule.SerializeToString(),
+      caller_ip=ipaddr.ip_to_string(caller_ip),
+      auth_service_version=utils.get_app_version(),
+      issuer_id=subtoken.issuer_id,
+      creation_time=utils.timestamp_to_datetime(subtoken.creation_time*1e6),
+      services=list(subtoken.services or ['*']),
+      impersonator_id=subtoken.impersonator_id)
+  entity.put(use_cache=False, use_memcache=False)
+  subtoken_id = entity.key.integer_id()
+
+  # Keep a logging entry (extractable via BigQuery) too.
+  logging.info(
+      'subtoken: subtoken_id=%d caller_ip=%s issuer_id=%s impersonator_id=%s',
+      subtoken_id, entity.caller_ip, entity.issuer_id, entity.impersonator_id)
+
+  return subtoken_id