By default, the root user or any user in the haclient group can modify Pacemaker’s CIB without restriction. Pacemaker offers access control lists (ACLs) to provide more fine-grained authorization.
Important
Being able to modify the CIB’s resource section allows a user to run any executable file as root, by configuring it as an LSB resource with a full path.
In order to use ACLs:
ACLs are specified within an acls element of the CIB. The acls element may contain any number of acl_role, acl_target, and acl_group elements.
An ACL role is a collection of permissions allowing or denying access to particular portions of the CIB. A role is configured with an acl_role element in the CIB acls section.
| Attribute | Description |
|---|---|
| id | A unique name for the role (required) |
| description | Arbitrary text (not used by Pacemaker) |
An acl_role element may contain any number of acl_permission elements.
| Attribute | Description |
|---|---|
| id | A unique name for the permission (required) |
| description | Arbitrary text (not used by Pacemaker) |
| kind | The access being granted. Allowed values are read, write, and deny. A value of write grants both read and write access. |
| object-type | The name of an XML element in the CIB to which the permission applies. (Exactly one of object-type, xpath, and reference must be specified for a permission.) |
| attribute | If specified, the permission applies only to object-type elements that have this attribute set (to any value). If not specified, the permission applies to all object-type elements. May only be used with object-type. |
| reference | The ID of an XML element in the CIB to which the permission applies. (Exactly one of object-type, xpath, and reference must be specified for a permission.) |
| xpath | An XPath [https://www.w3.org/TR/xpath-10/] specification selecting an XML element in the CIB to which the permission applies. Attributes may be specified in the XPath to select particular elements, but the permissions apply to the entire element. (Exactly one of object-type, xpath, and reference must be specified for a permission.) |
Important
ACL targets correspond to user accounts on the system.
| Attribute | Description |
|---|---|
| id | The name of a user on the system (required) |
ACL groups may be specified, but are not currently used by Pacemaker. This is expected to change in a future version.
| Attribute | Description |
|---|---|
| id | The name of a group on the system (required) |
Each acl_target and acl_group element may contain any number of role elements.
| Attribute | Description |
|---|---|
| id | The id of an acl_role element that specifies permissions granted to the enclosing target or group. |
Important
The root and hacluster user accounts always have full access to the CIB, regardless of ACLs. For all other user accounts, when enable-acl is true, permission to all parts of the CIB is denied by default (permissions must be explicitly granted).
<acls>
<acl_role id="read_all">
<acl_permission id="read_all-cib" kind="read" xpath="/cib" />
</acl_role>
<acl_role id="operator">
<acl_permission id="operator-maintenance-mode" kind="write"
xpath="//crm_config//nvpair[@name='maintenance-mode']" />
<acl_permission id="operator-maintenance-attr" kind="write"
xpath="//nvpair[@name='maintenance']" />
<acl_permission id="operator-target-role" kind="write"
xpath="//resources//meta_attributes/nvpair[@name='target-role']" />
<acl_permission id="operator-is-managed" kind="write"
xpath="//resources//nvpair[@name='is-managed']" />
<acl_permission id="operator-rsc_location" kind="write"
object-type="rsc_location" />
</acl_role>
<acl_role id="administrator">
<acl_permission id="administrator-cib" kind="write" xpath="/cib" />
</acl_role>
<acl_role id="minimal">
<acl_permission id="minimal-standby" kind="read"
description="allow reading standby node attribute (permanent or transient)"
xpath="//instance_attributes/nvpair[@name='standby']"/>
<acl_permission id="minimal-maintenance" kind="read"
description="allow reading maintenance node attribute (permanent or transient)"
xpath="//nvpair[@name='maintenance']"/>
<acl_permission id="minimal-target-role" kind="read"
description="allow reading resource target roles"
xpath="//resources//meta_attributes/nvpair[@name='target-role']"/>
<acl_permission id="minimal-is-managed" kind="read"
description="allow reading resource managed status"
xpath="//resources//meta_attributes/nvpair[@name='is-managed']"/>
<acl_permission id="minimal-deny-instance-attributes" kind="deny"
xpath="//instance_attributes"/>
<acl_permission id="minimal-deny-meta-attributes" kind="deny"
xpath="//meta_attributes"/>
<acl_permission id="minimal-deny-operations" kind="deny"
xpath="//operations"/>
<acl_permission id="minimal-deny-utilization" kind="deny"
xpath="//utilization"/>
<acl_permission id="minimal-nodes" kind="read"
description="allow reading node names/IDs (attributes are denied separately)"
xpath="/cib/configuration/nodes"/>
<acl_permission id="minimal-resources" kind="read"
description="allow reading resource names/agents (parameters are denied separately)"
xpath="/cib/configuration/resources"/>
<acl_permission id="minimal-deny-constraints" kind="deny"
xpath="/cib/configuration/constraints"/>
<acl_permission id="minimal-deny-topology" kind="deny"
xpath="/cib/configuration/fencing-topology"/>
<acl_permission id="minimal-deny-op_defaults" kind="deny"
xpath="/cib/configuration/op_defaults"/>
<acl_permission id="minimal-deny-rsc_defaults" kind="deny"
xpath="/cib/configuration/rsc_defaults"/>
<acl_permission id="minimal-deny-alerts" kind="deny"
xpath="/cib/configuration/alerts"/>
<acl_permission id="minimal-deny-acls" kind="deny"
xpath="/cib/configuration/acls"/>
<acl_permission id="minimal-cib" kind="read"
description="allow reading cib element and crm_config/status sections"
xpath="/cib"/>
</acl_role>
<acl_target id="alice">
<role id="minimal"/>
</acl_target>
<acl_target id="bob">
<role id="read_all"/>
</acl_target>
<acl_target id="carol">
<role id="read_all"/>
<role id="operator"/>
</acl_target>
<acl_target id="dave">
<role id="administrator"/>
</acl_target>
</acls>
In the above example, the user alice has the minimal permissions necessary to run basic Pacemaker CLI tools, including using crm_mon to view the cluster status, without being able to modify anything. The user bob can view the entire configuration and status of the cluster, but not make any changes. The user carol can read everything, and change selected cluster properties as well as resource roles and location constraints. Finally, dave has full read and write access to the entire CIB.
Looking at the minimal role in more depth, it is designed to allow read access to the cib tag itself, while denying access to particular portions of its subtree (which is the entire CIB).
This is because the DC node is indicated in the cib tag, so crm_mon will not be able to report the DC otherwise. However, this does change the security model to allow by default, since any portions of the CIB not explicitly denied will be readable. The cib read access could be removed and replaced with read access to just the crm_config and status sections, for a safer approach at the cost of not seeing the DC in status output.
For a simpler configuration, the minimal role allows read access to the entire crm_config section, which contains cluster properties. It would be possible to allow read access to specific properties instead (such as stonith-enabled, dc-uuid, have-quorum, and cluster-name) to restrict access further while still allowing status output, but cluster properties are unlikely to be considered sensitive.
ACLs apply only to the CIB.
That means ACLs apply to command-line tools that operate by reading or writing the CIB, such as crm_attribute when managing permanent node attributes, crm_mon, and cibadmin.
However, command-line tools that communicate directly with Pacemaker daemons via IPC are not affected by ACLs. For example, users in the haclient group may still do the following, regardless of ACLs:
ACLs apply to commands run on Pacemaker Remote nodes using the Pacemaker Remote node’s name as the ACL user name.
The idea is that Pacemaker Remote nodes (especially virtual machines and containers) are likely to be purpose-built and have different user accounts from full cluster nodes.