openSolaris 2008 - Network Security Attributes in Trusted Extensions - Solaris Trusted Extensions Administrator's Procedures

Network Security Attributes in Trusted Extensions

Trusted Extensions is installed with a default set of security templates. When a template is assigned to a host, the security values in the template are applied to the host. In Trusted Extensions, both unlabeled hosts and labeled hosts on the network are assigned security attributes by means of a template. Hosts that are not assigned a security template cannot be reached. The templates can be stored locally, or in the LDAP naming service on the Sun Java System Directory Server.

Templates can be assigned directly or indirectly to a host. Direct assignment assigns a template to a particular IP address. Indirect assignment assigns a template to a network address that includes the host. Hosts that do not have a security template cannot communicate with hosts that are configured with Trusted Extensions. For an explanation of direct assignment and indirect assignment, see Trusted Network Fallback Mechanism.

Templates are modified or created by using the Security Templates tool in the Solaris Management Console. The Security Templates tool enforces the completion of the required fields in the templates. Which fields are required is based on the host type.

Each host type has its own set of additional required and optional security attributes. The following security attributes are specified in security templates:

Host type – Defines whether the packets are labeled with CIPSO security labels or not labeled at all.
Default label – Defines the level of trust of the unlabeled host. Packets that are sent by an unlabeled host are read at this label by the receiving Trusted Extensions host or gateway.
The Default label attribute is specific to the unlabeled host type. For details, see the smtnrhtp(1M) man page and the following sections.
DOI – A positive, non-zero integer that identifies the domain of interpretation. The DOI is used to indicate which set of label encodings applies to a network communication or network entity. Labels with different DOIs, even if otherwise identical, are disjoint. For unlabeled hosts, the DOI applies to the default label. In Trusted Extensions, the default value is 1.
Minimum label – Defines the bottom of the label accreditation range. Hosts and next-hop gateways do not receive packets that are below the minimum label that is specified in their template.
Maximum label – Defines the top of the label accreditation range. Hosts and next-hop gateways do not receive packets that are higher than the maximum label that is specified in their template.
Security label set – Optional. Specifies a discrete set of security labels for a security template. In addition to their accreditation range that is determined by the maximum and minimum label, hosts that are assigned to a template with a security label set can send and receive packets that match any one of the labels in the label set. The maximum number of labels that can be specified is four.

Host Type and Template Name in Security Templates

Trusted Extensions supports two host types in the trusted network databases and provides two default templates:

CIPSO host type – Intended for hosts that run trusted operating systems. Trusted Extensions supplies the template named cipso for this host type.
The Common IP Security Option (CIPSO) protocol is used to specify security labels that are passed in the IP options field. CIPSO labels are derived automatically from the data's label. Tag type 1 is used to pass the CIPSO security label. This label is then used to make security checks at the IP level and to label the data in the network packet.
Unlabeled host type - Intended for hosts that use standard networking protocols but do not support CIPSO options. Trusted Extensions supplies the template named admin_low for this host type.
This host type is assigned to hosts that run the Solaris OS or other unlabeled operating systems. This host type gives provides a default label and a default clearance to apply to communications with the unlabeled host. Also, a label range or a set of discrete labels can be specified to allow the sending of packets to an unlabeled gateway for forwarding.

Caution - The admin_low template provides an example for constructing unlabeled templates with site-specific labels. While the admin_low template is required for the installation of Trusted Extensions, the security settings might not be appropriate for normal system operations. Retain the provided templates without modification for system maintenance and support reasons.

Default Label in Security Templates

Templates for the unlabeled host type specify a default label. This label is used to control communications with hosts whose operating systems are not aware of labels, such as Solaris systems. The default label that is assigned reflects the level of trust that is appropriate for the host and its users.

Because communications with unlabeled hosts are essentially limited to the default label, these hosts are also referred to as single-label hosts.

Domain of Interpretation in Security Templates

Organizations that use the same Domain of Interpretation (DOI) agree among themselves to interpret label information and other security attributes in the same way. When Trusted Extensions performs a label comparison, a check is made as to whether the DOI is equal.

A Trusted Extensions system enforces label policy on one DOI value. All zones on a Trusted Extensions system must operate at the same DOI. A Trusted Extensions system does not provide exception handling on packets that are received from a system that uses a different DOI.

If your site uses a DOI value that is different from the default value, you must add this value to the /etc/system file, and change the value in every security template. For the initial procedure, see Configure the Domain of Interpretation. To configure the DOI in every security template, see Example 19-1.

Label Range in Security Templates

The minimum label and maximum label attributes are used to establish the label range for labeled and unlabeled hosts. These attributes are used to do the following:

To set the range of labels that can be used when communicating with a remote CIPSO host
In order for a packet to be sent to a destination host, the label of the packet must be within the label range assigned to the destination host in the security template for that host.
To set a label range for packets that are being forwarded through a CIPSO gateway or an unlabeled gateway
The label range can be specified in the template for an unlabeled host type. The label range enables the host to forward packets that are not necessarily at the label of the host, but are within a specified label range.

Security Label Set in Security Templates

The security label set defines at most four discrete labels at which packets can be accepted, forwarded, or sent by the remote host. This attribute is optional. By default, no security label set is defined.