Access Control

Use this topic to learn about controlling access to Cloud Filestore instances.

Cloud Filestore doesn't support Kerberos for securing access to Cloud Filestore instances. Use the Linux and Cloud Identity and Access Management (IAM) options described below instead.

Fileshare export settings

A Cloud Filestore fileshare is assigned fixed /etc/exports settings, as follows:

• The client list, which identifies the clients allowed to connect to the fileshare, is composed of all internal IP addresses in the VPC network you selected for the Cloud Filestore instance. Internal IP addresses are those in ranges 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 per RFC 1918.
• The rw option is used, so the fileshare is read-write.
• The user ID mapping option no_root_squash is used, so all users and groups, including the root user, are expected to be the same on both the Cloud Filestore instance and the client.
• All other options use the /etc/exports defaults.

You can't change fileshare export settings.

Fileshare permissions

When you create a Cloud Filestore instance, the fileshare for that instance has default Unix permissions of rwxr-xr-x, octal notation 755. These permissions mean that on a Cloud Filestore instance, only root users on connected clients have read/write access to the fileshare. Other users have only read access by default, but client root users can change permissions and owners.

Configuring access on a fileshare

When mounting a Cloud Filestore fileshare on a client, you can use options for the mount command and settings in the /etc/fstab file to determine whether the mounted fileshare is writable and if files can be executed on it. After mounting the fileshare, you can use standard Linux commands like chmod, and setfacl to set file and fileshare permissions.

Setting consistent permissions

We strongly recommend that you set consistent permissions for each user on all clients that connect to the same Cloud Filestore instance, because of an issue that occurs when:

• A fileshare is mounted on more than one client, and
• A user has root permission on one client but not the others

The user can upload a file with the setuid bit set from the client where they have root access, which then allows them to execute the file as root on any other client where they have at least read permission. This is because the setuid bit allows a user to execute a file using the permissions of the file owner, in this case root.

IAM roles and permissions

You grant access to Cloud Filestore operations by using Cloud Identity and Access Management (IAM) roles.

IAM permissions only control access to Cloud Filestore operations, like creating a Cloud Filestore instance. Access to operations on the Cloud Filestore fileshare, like read or execute, are determined by Linux permissions.

Using Cloud Filestore roles

You can use the Cloud Filestore Editor and Cloud Filestore Viewer roles to grant Cloud Filestore permissions to users. If you prefer, you can also use primitive roles for this purpose.

Use the following table to see the Cloud Filestore permissions associated with Cloud Filestore roles.

Permission	Action	Cloud Filestore Editor role	Cloud Filestore Viewer role
file.locations.get	Get information about a specific location supported by this service.	X	X
file.locations.list	List information about the supported locations for this service.	X	X
file.instances.create	Create a Cloud Filestore instance.	X
file.instances.update	Update a Cloud Filestore instance.	X
file.instances.delete	Delete a Cloud Filestore instance.	X
file.instances.get	Get details about a specific Cloud Filestore instance.	X	X
file.instances.list	List the Cloud Filestore instances in the project.	X	X
file.operations.get	Get the status of a Cloud Filestore instance operation.	X	X
file.operations.list	List Cloud Filestore instance operations.	X	X
file.operations.cancel	Cancel a Cloud Filestore instance operation.	X
file.operations.delete	Delete a Cloud Filestore instance operation.	X

Using primitive roles

Cloud Filestore permissions are also associated with the IAM primitive roles of owner, editor, and viewer. You can use these roles in addition to the Cloud Filestore roles to grant Cloud Filestore permissions to users.

Use the following table to see the Cloud Filestore permissions associated with primitive roles.

Permission	Action	Project Owner role	Project Editor role	Project Viewer role
file.locations.get	Get information about a specific location supported by this service.	X	X	X
file.locations.list	List information about the supported locations for this service.	X	X	X
file.instances.create	Create a Cloud Filestore instance.	X	X
file.instances.update	Update a Cloud Filestore instance.	X	X
file.instances.delete	Delete a Cloud Filestore instance.	X	X
file.instances.get	Get details about a specific Cloud Filestore instance.	X	X	X
file.instances.list	List the Cloud Filestore instances in the project.	X	X	X
file.operations.get	Get the status of a Cloud Filestore instance operation.	X	X	X
file.operations.list	List Cloud Filestore instance operations.	X	X	X
file.operations.cancel	Cancel a Cloud Filestore instance operation.	X	X
file.operations.delete	Delete a Cloud Filestore instance operation.	X	X

Custom roles

If the predefined IAM roles don't meet your needs, you can define custom role with permissions that you specify. To support this, IAM offers custom roles. When you create custom roles for Cloud Filestore, make sure that you include both resourcemanager.projects.get and resourcemanager.projects.list so that the role has permission to query project resources. Otherwise, the GCP console won't function correctly for Cloud Filestore.