Add KMS policy actions

Adds the following to the KMS service
* PutKeyPolicy
* GetKeyPolicy
* ListKeyPolicies

Signed-off-by: Jesse Szwedko <jesse.szwedko@getbraintree.com>

moto/kms/models.py

@@ -78,6 +78,12 @@ class KmsBackend(BaseBackend):
     def get_key_rotation_status(self, key_id):
         return self.keys[key_id].key_rotation_status
 
+    def put_key_policy(self, key_id, policy):
+        self.keys[key_id].policy = policy
+
+    def get_key_policy(self, key_id):
+        return self.keys[key_id].policy
+
 
 kms_backends = {}
 for region in boto.kms.regions():

moto/kms/responses.py

@@ -171,6 +171,53 @@ class KmsResponse(BaseResponse):
                 '__type': 'NotFoundException'})
         return json.dumps({'KeyRotationEnabled': rotation_enabled})
 
+    def put_key_policy(self):
+        key_id = self.parameters.get('KeyId')
+        policy_name = self.parameters.get('PolicyName')
+        policy = self.parameters.get('Policy')
+        _assert_valid_key_id(key_id)
+        _assert_default_policy(policy_name)
+
+        try:
+            self.kms_backend.put_key_policy(key_id, policy)
+        except KeyError:
+            raise JSONResponseError(404, 'Not Found', body={
+                'message': "Key 'arn:aws:kms:{region}:012345678912:key/{key_id}' does not exist".format(region=self.region,key_id=key_id),
+                '__type': 'NotFoundException'})
+
+        return json.dumps(None)
+
+    def get_key_policy(self):
+        key_id = self.parameters.get('KeyId')
+        policy_name = self.parameters.get('PolicyName')
+        _assert_valid_key_id(key_id)
+        _assert_default_policy(policy_name)
+
+        try:
+            return json.dumps({'Policy': self.kms_backend.get_key_policy(key_id)})
+        except KeyError:
+            raise JSONResponseError(404, 'Not Found', body={
+                'message': "Key 'arn:aws:kms:{region}:012345678912:key/{key_id}' does not exist".format(region=self.region,key_id=key_id),
+                '__type': 'NotFoundException'})
+
+    def list_key_policies(self):
+        key_id = self.parameters.get('KeyId')
+        _assert_valid_key_id(key_id)
+        try:
+            self.kms_backend.describe_key(key_id)
+        except KeyError:
+            raise JSONResponseError(404, 'Not Found', body={
+                'message': "Key 'arn:aws:kms:{region}:012345678912:key/{key_id}' does not exist".format(region=self.region,key_id=key_id),
+                '__type': 'NotFoundException'})
+
+        return json.dumps({'Truncated': False, 'PolicyNames': ['default']})
+
 def _assert_valid_key_id(key_id):
     if not re.match(r'^[A-F0-9]{8}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{4}-[A-F0-9]{12}$', key_id, re.IGNORECASE):
         raise JSONResponseError(404, 'Not Found', body={'message': ' Invalid keyId', '__type': 'NotFoundException'})
+
+def _assert_default_policy(policy_name):
+    if policy_name != 'default':
+        raise JSONResponseError(404, 'Not Found', body={
+            'message': "No such policy exists",
+            '__type': 'NotFoundException'})