Chapter 8. Hardening Infrastructure and Virtualization

When you evaluate a hypervisor platform, consider the supportability of the hardware on which the hypervisor will run. Additionally, consider the additional features available in the hardware and how those features are supported by the hypervisor you chose as part of the OpenStack deployment. To that end, hypervisors each have their own hardware compatibility lists (HCLs). When selecting compatible hardware it is important to know in advance which hardware-based virtualization technologies are important from a security perspective.

PCI passthrough allows an instance to have direct access to a piece of hardware on the node. For example, this could be used to allow instances to access video cards or GPUs offering the compute unified device architecture (CUDA) for high performance computation. This feature carries two types of security risks: direct memory access and hardware infection.

Direct memory access (DMA) is a feature that permits certain hardware devices to access arbitrary physical memory addresses in the host computer. Often video cards have this capability. However, an instance should not be given arbitrary physical memory access because this would give it full view of both the host system and other instances running on the same node. Hardware vendors use an input/output memory management unit (IOMMU) to manage DMA access in these situations. You should confirm that the hypervisor is configured to use this hardware feature.

A hardware infection occurs when an instance makes a malicious modification to the firmware or some other part of a device. As this device is used by other instances or the host OS, the malicious code can spread into those systems. The end result is that one instance can run code outside of its security zone. This is a significant breach as it is harder to reset the state of physical hardware than virtual hardware, and can lead to additional exposure such as access to the management network.

Due to the risk and complexities associated with PCI passthrough, it should be disabled by default. If enabled for a specific need, you will need to have appropriate processes in place to help ensure the hardware is clean before reuse.

Security-Enhanced Linux (SELinux) is an implementation of mandatory access control (MAC). MAC limits the impact of an attack by restricting what a process or application is permitted to do on a system. For more information on SELinux, see What is SELinux?.

SELinux policies have been pre-configured for Red Hat OpenStack Platform (RHOSP) services. On RHOSP, SELinux is configured to run each QEMU process under a separate security context. In RHOSP, SELinux policies help protect hypervisor hosts and instances against the following threats:

In RHOSP, instance image files on disk are labeled with SELinux data type svirt_image_t. When the instance is powered on, SELinux appends a random numerical identifier to the image. A random numerical identifier can prevent a compromised OpenStack instance from gaining unauthorized access to other containers. SELinux is capable of assigning up to 524,288 numeric identifiers on each hypervisor node.

The OpenStack services that come with Red Hat OpenStack Platform run within containers. Containerization allows for the development and upgrade of services without dependency related conflicts. When a service runs within a container, potential vulnerabilities to that service are also contained.

You can get information about the service that are running in your environment by using the following steps:

You can make changes to containerized services that persist when the container is restarted, but that do not affect the permanent configuration of your Red Hat OpenStack Platform (RHOSP) cluster. This is useful for testing configuration changes, or enabling debug-level logs when troubleshooting. You can revert changes manually. Alternatively, running a redeploy on your RHOSP cluster resets all parameters to their permanent configurations.

Use configuration files that are located in /var/lib/config-data/puppet-generated/[service] to make temporary changes to a service. The following example enables debugging on the nova service:

You can make permanent changes to containerized services in Red Hat OpenStack Platform (RHOSP) services with heat. Use an existing template that you used when you first deployed RHOSP, or create a new template to add to your deployment script. In the following example, the private key size for libvirt is increased to 4096.

Physical servers use complex firmware to enable and operate server hardware and lights-out management cards, which can have their own security vulnerabilities, potentially allowing system access and interruption. To address these, hardware vendors will issue firmware updates, which are installed separately from operating system updates. You will need an operational security process that retrieves, tests, and implements these updates on a regular schedule, noting that firmware updates often require a reboot of physical hosts to become effective.

You can set a banner that displays a console message to all users that connect over SSH. You can add banner text to /etc/issue using the following parameters in an environment file. Consider customizing this sample text to suit your requirements.

resource_registry:
  OS::TripleO::Services::Sshd:
    /usr/share/openstack-tripleo-heat-templates/deployment/sshd/sshd-baremetal-puppet.yaml

parameter_defaults:
  BannerText: |
   ******************************************************************
   * This system is for the use of authorized users only. Usage of  *
   * this system may be monitored and recorded by system personnel. *
   * Anyone using this system expressly consents to such monitoring *
   * and is advised that if such monitoring reveals possible        *
   * evidence of criminal activity, system personnel may provide    *
   * the evidence from such monitoring to law enforcement officials.*
   ******************************************************************

To apply this change to your deployment, save the settings as a file called ssh_banner.yaml, and then pass it to the overcloud deploy command as follows. The <full environment> indicates that you must still include all of your original deployment parameters. For example:

    openstack overcloud deploy --templates \
      -e <full environment> -e  ssh_banner.yaml

Maintaining a record of all audit events helps you establish a system baseline, perform troubleshooting, or analyze the sequence of events that led to a certain outcome. The audit system is capable of logging many types of events, such as changes to the system time, changes to Mandatory/Discretionary Access Control, and creating/deleting users or groups.

Rules can be created using an environment file, which are then injected by director into /etc/audit/audit.rules. For example:

    resource_registry:
      OS::TripleO::Services::AuditD: /usr/share/openstack-tripleo-heat-templates/deployment/auditd/auditd-baremetal-puppet.yaml
    parameter_defaults:
      AuditdRules:
        'Record Events that Modify User/Group Information':
          content: '-w /etc/group -p wa -k audit_rules_usergroup_modification'
          order  : 1
        'Collects System Administrator Actions':
          content: '-w /etc/sudoers -p wa -k actions'
          order  : 2
        'Record Events that Modify the Systems Mandatory Access Controls':
          content: '-w /etc/selinux/ -p wa -k MAC-policy'
          order  : 3

Firewall rules are automatically applied on overcloud nodes during deployment, and are intended to only expose the ports required to get OpenStack working. You can specify additional firewall rules as needed. For example, to add rules for a Zabbix monitoring system:

    parameter_defaults:
      ControllerExtraConfig:
        tripleo::firewall::firewall_rules:
          '301 allow zabbix':
            dport: 10050
            proto: tcp
            source: 10.0.0.8
            action: accept

You can also add rules that restrict access. The number used during rule definition will determine the rule’s precedence. For example, RabbitMQ’s rule number is 109 by default. If you want to restrain it, you switch it to use a lower value:

    parameter_defaults:
      ControllerExtraConfig:
        tripleo::firewall::firewall_rules:
          '098 allow rabbit from internalapi network':
            dport: [4369,5672,25672]
            proto: tcp
            source: 10.0.0.0/24
            action: accept
          '099 drop other rabbit access':
            dport: [4369,5672,25672]
            proto: tcp
            action: drop

In this example, 098 and 099 are arbitrarily chosen numbers that are lower than RabbitMQ’s rule number 109. To determine a rule’s number, you can inspect the iptables rule on the appropriate node; for RabbitMQ, you would check the controller:

iptables-save
[...]
-A INPUT -p tcp -m multiport --dports 4369,5672,25672 -m comment --comment "109 rabbitmq" -m state --state NEW -j ACCEPT

Alternatively, you can extract the port requirements from the puppet definition. For example, RabbitMQ’s rules are stored in puppet/services/rabbitmq.yaml:

    tripleo.rabbitmq.firewall_rules:
      '109 rabbitmq':
        dport:
          - 4369
          - 5672
          - 25672

The following parameters can be set for a rule:

AIDE (Advanced Intrusion Detection Environment) is a file and directory integrity checker. It is used to detect incidents of unauthorized file tampering or changes. For example, AIDE can alert you if system password files are changed.

AIDE works by analyzing system files and then compiling an integrity database of file hashes. The database then serves as a comparison point to verify the integrity of the files and directories and detect changes.

The director includes the AIDE service, allowing you to add entries into an AIDE configuration, which is then used by the AIDE service to create an integrity database. For example:

  resource_registry:
    OS::TripleO::Services::Aide:
      /usr/share/openstack-tripleo-heat-templates/deployment/aide/aide-baremetal-ansible.yaml

  parameter_defaults:
    AideRules:
      'TripleORules':
        content: 'TripleORules = p+sha256'
        order: 1
      'etc':
        content: '/etc/ TripleORules'
        order: 2
      'boot':
        content: '/boot/ TripleORules'
        order: 3
      'sbin':
        content: '/sbin/ TripleORules'
        order: 4
      'var':
        content: '/var/ TripleORules'
        order: 5
      'not var/log':
        content: '!/var/log.*'
        order: 6
      'not var/spool':
        content: '!/var/spool.*'
        order: 7
      'not nova instances':
        content: '!/var/lib/nova/instances.*'
        order: 8

For a complete list of attributes available for AIDE’s config files, see the AIDE MAN page at https://aide.github.io/.

Complete the following to apply changes to your deployment:

    MyAlias = p+i+n+u+g+s+b+m+c+sha512

SecureTTY allows you to disable root access for any console device (tty). This behavior is managed by entries in the /etc/securetty file. For example:

  resource_registry:
    OS::TripleO::Services::Securetty: ../puppet/services/securetty.yaml

  parameter_defaults:
    TtyValues:
      - console
      - tty1
      - tty2
      - tty3
      - tty4
      - tty5
      - tty6

A thorough auditing process can help you review the ongoing security posture of your OpenStack deployment. This is especially important for keystone, due to its role in the security model.

Red Hat OpenStack Platform has adopted Cloud Auditing Data Federation (CADF) as the data format for audit events, with the keystone service generating CADF events for Identity and Token operations. You can enable CADF auditing for keystone using KeystoneNotificationFormat:

  parameter_defaults:
    KeystoneNotificationFormat: cadf

To enforce password requirements for new system users (non-keystone), director can add entries to /etc/login.defs by following these example parameters:

  resource_registry:
    OS::TripleO::Services::LoginDefs: ../puppet/services/login-defs.yaml

  parameter_defaults:
    PasswordMaxDays: 60
    PasswordMinDays: 1
    PasswordMinLen: 5
    PasswordWarnAge: 7
    FailDelay: 4