auth: Keep audit log of all generated delegation tokens.

appengine/auth_service/delegation.py

 # Copyright 2015 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """API handler to mint delegation tokens."""
 
 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
 
 import config
 
 
 # Minimum accepted value for 'validity_duration'.
 MIN_VALIDITY_DURATION_SEC = 30
 
@@ skipping 47 matching lines @@
   @auth.require(lambda: not auth.get_current_identity().is_anonymous)
   def post(self):
     # Forbid usage of delegation tokens for this particular call. Using
     # delegation when creating delegation tokens is too deep. Redelegation will
     # be done as separate explicit API call that accept existing delegation
     # token via request body, not via headers.
     if auth.get_current_identity() != auth.get_peer_identity():
       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:
       self.abort_with_error(400, text=str(exc))
 
     # Fill in defaults.
     assert not subtoken.impersonator_id
     user_id = auth.get_current_identity().to_bytes()
     if not subtoken.issuer_id:
       subtoken.issuer_id = user_id
     if subtoken.issuer_id != user_id:
       subtoken.impersonator_id = user_id
     subtoken.creation_time = int(utils.time_time())
     if not subtoken.validity_duration:
       subtoken.validity_duration = DEF_VALIDITY_DURATION_SEC
     if not subtoken.services or '*' in subtoken.services:
       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:
       token = delegation.serialize_token(
           delegation.seal_token(
               delegation_pb2.SubtokenList(subtokens=[subtoken])))
     except delegation.BadTokenError as exc:
       # This happens if resulting token is too large.
       self.abort_with_error(400, text=str(exc))
 
@@ skipping 64 matching lines @@
     try:
       auth.Identity.from_bytes(imp)
     except ValueError as exc:
       raise ValueError(
           'Invalid identity name "%s" in "impersonate": %s' % (imp, exc))
     msg.issuer_id = str(imp)
 
   return msg
 
 
+################################################################################
+
+
 # Fallback rule returned if nothing else matches.
 DEFAULT_RULE = config_pb2.DelegationConfig.Rule(
     user_id=['*'],
     target_service=['*'],
     max_validity_duration=MAX_VALIDITY_DURATION_SEC)
 
 
 def get_delegation_rule(user_id, services):
   """Returns first matching rule from delegation.cfg DelegationConfig rules.
 
@@ skipping 40 matching lines @@
     return False
 
 
 def check_can_create_token(user_id, subtoken):
   """Checks that caller is allowed to mint a given root token.
 
   Args:
     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.
   """
   rule = get_delegation_rule(user_id, subtoken.services)
 
   if subtoken.validity_duration > rule.max_validity_duration:
     raise auth.AuthorizationError(
         'Maximum allowed validity_duration is %d sec, %d requested.' %
         (rule.max_validity_duration, subtoken.validity_duration))
 
   # 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' %
       (user_id, subtoken.issuer_id, subtoken.services or ['*']))
 
 
 def get_default_allowed_services(user_id):
   """Returns the list of services defined by a first matching rule.
 
   Args:
     user_id: identity string of a current caller.
   """
   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