Share access control

Share access control

The Shared File Systems service allows to grant or deny access to different entities of the service for other clients.

Having a share as remote mountable instance of a file system, you can manage access to a specified share, and list permissions for a specified share.

A share can be public or private. This is a level of visibility for the share that defines whether other tenants can or cannot see the share. By default, all shares are created as private. While creating a share, use key --public to make your share public for other tenants to see it in a list of shares and see its detailed information.

According to a policy.json file, an administrator and the users as share owners can manage access to shares by means of creating access rules. Using manila access-allow, manila access-deny and manila access-list commands, you can grant, deny and list access to a specified share correspondingly.

Tip

By default, when a share is created and has its export location, the Shared File Systems service expects that nobody can access the share by mounting it. Please note that the share driver you use can change this configuration, or it can be directly changed on the share storage. To ensure access to the share, check the mounting config for the export protocol.

When a share is just created there are no default access rules associated with it and permission to mount it. This could be seen in mounting config for export protocol in use. For example, there is an NFS command exportfs or /etc/exports file on the storage which controls each remote share and defines hosts that can access it. It is empty if nobody can mount a share. For a remote CIFS server there is net conf list command which shows the configuration. hosts deny parameter should be set by the share driver to 0.0.0.0/0 which means that any host is denied to mount the share.

Using the Shared File Systems service, you can grant or deny access to a share by specifying one of these supported share access levels:

  • rw. Read and write (RW) access. This is the default value.

  • ro. Read-only (RO) access.

Tip

The RO access level can be helpful in public shares when the administrator gives read and write (RW) access for some certain editors or contributors and gives read-only (RO) access for the rest of users (viewers).

You must also specify one of these supported authentication methods:

  • ip. Authenticates an instance by its IP address. A valid format is XX.XX.XX.XX or XX.XX.XX.XX/XX. For example 0.0.0.0/0.

  • cert. Authenticates an instance by a TLS certificate. Specify the TLS identity as the IDENTKEY. A valid value is any string up to 64 characters long in the common name (CN) of the certificate.

  • user. Authenticates by a specified user or group name. A valid value is an alphanumeric string that can contain some special characters and is from 4 to 32 characters long.

Note

Supported authentication methods depend on which share driver, security service and shared file system protocol you configure and use. Supported shared file system protocols are NFS, CIFS, GlusterFS, and HDFS. Supported security services are LDAP, Kerberos protocols, or Microsoft Active Directory service. For details of supporting of features by different drivers, see Manila share features support mapping.

To verify that access rules (ACL) were configured correctly for a share, you can list its permissions.

Tip

You also can choose and add the security service that is supported by the share driver to create access rules with authentication methods for clients that are appropriate for your share. Supported security services are LDAP, Kerberos and Microsoft Active Directory.

Below is an example of an NFS share with the Generic driver. After the share was created it has export location 10.254.0.3:/shares/share-b2874f8d-d428-4a5c-b056-e6af80a995de. If you try to mount it on the host with 10.254.0.4 IP address, you’ll get a “Permission denied” message.

# mount.nfs -v 10.254.0.3:/shares/share-b2874f8d-d428-4a5c-b056-e6af80a995de /mnt
mount.nfs: timeout set for Mon Oct 12 13:07:47 2015
mount.nfs: trying text-based options 'vers=4,addr=10.254.0.3,clientaddr=10.254.0.4'
mount.nfs: mount(2): Permission denied
mount.nfs: access denied by server while mounting 10.254.0.3:/shares/share-b2874f8d-...

As an administrator, you can connect through SSH to a host with 10.254.0.3 IP address, check the /etc/exports file on it and see that it is empty:

# cat /etc/exports
#

The Generic driver we use in example does not support any of the security services, thus with NFS shared file system protocol we can grant access only through the IP address:

$ manila access-allow Share_demo2 ip 10.254.0.4
+--------------+--------------------------------------+
| Property     | Value                                |
+--------------+--------------------------------------+
| share_id     | e57c25a8-0392-444f-9ffc-5daadb9f756c |
| access_type  | ip                                   |
| access_to    | 10.254.0.4                           |
| access_level | rw                                   |
| state        | new                                  |
| id           | 62b8e453-d712-4074-8410-eab6227ba267 |
+--------------+--------------------------------------+

After the rule has status active we can connect to the 10.254.0.3 host again and check the /etc/exports file and see that the line with rule was added:

# cat /etc/exports
/shares/share-b2874f8d-d428-4a5c-b056-e6af80a995de     10.254.0.4(rw,sync,wdelay,hide,nocrossmnt,secure,root_squash,no_all_squash,no_subtree_check,secure_locks,acl,anonuid=65534,anongid=65534,sec=sys,rw,root_squash,no_all_squash)
#

Now we can mount a share on the host with IP address 10.254.0.4 and have rw permissions to the share:

# mount.nfs -v 10.254.0.3:/shares/share-b2874f8d-d428-4a5c-b056-e6af80a995de /mnt
# ls -a /mnt
.  ..  lost+found
# echo "Hello!" > /mnt/1.txt
# ls -a /mnt
.  ..  1.txt  lost+found
#
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