The Trusted Network

Trusted Extensions assigns security attributes to zones, hosts, and networks. These attributes ensure that the following security features are enforced on the network:

• Data is properly labeled in network communications.

• Mandatory access control (MAC) rules are enforced when data is sent or received across a local network and when file systems are mounted.

• MAC rules are enforced when data is routed to distant networks.

• MAC rules are enforced when data is routed to zones.

In Trusted Extensions, network packets are protected by MAC. Labels are used for MAC decisions. Data is labeled explicitly or implicitly with a sensitivity label. A label has an ID field, a classification or “level” field, and a compartment or “category” field. Data must pass an accreditation check. This check determines if the label is well formed, and if the label lies within the accreditation range of the receiving host. Well-formed packets that are within the receiving host's accreditation range are granted access.

IP packets that are exchanged between trusted systems can be labeled. Trusted Extensions supports Commercial IP Security Option (CIPSO) labels. A CIPSO label on a packet serves to classify, segregate, and route IP packets. Routing decisions compare the sensitivity label of the data with the label of the destination.

Typically on a trusted network, the label is generated by a sending host and processed by the receiving host. However, a trusted router can also add or strip labels while forwarding packets in a trusted network. A sensitivity label is mapped to a CIPSO label before transmission. The CIPSO label is embedded in the IP packet. Typically, a packet sender and the packet's receiver operate at the same label.

Trusted networking software ensures that the Trusted Extensions security policy is enforced even when the subjects (processes) and objects (data) are located on different hosts. Trusted Extensions networking preserves MAC across distributed applications.

Trusted Extensions Data Packets

Trusted Extensions data packets include a CIPSO label option. The data packets can be sent over IPv4 or IPv6 networks.

In the standard IPv4 format, the IPv4 header with options is followed by a TCP, UDP, or SCTP header and then the actual data. The Trusted Extensions version of an IPv4 packet uses the CIPSO option in the IP header for the security attributes.

IPv4 Header With CIPSO Option

TCP, UDP, or SCTP

Data

In the standard IPv6 format, an IPv6 header with extensions is followed by a TCP, UDP, or SCTP header and then the actual data. The Trusted Extensions IPv6 packet includes a multilevel security option in the header extensions.

IPv6 Header With Extensions

TCP, UDP, or SCTP

Data

Trusted Network Communications

Trusted Extensions supports labeled and unlabeled hosts on a trusted network. LDAP is a fully supported naming service. Various commands and GUIs enable the network to be administered.

Systems that run Trusted Extensions software support network communications between Trusted Extensions hosts and any of the following types of systems:

• Other systems that are running Trusted Extensions

• Systems that are running operating systems that do not recognize security attributes, but do support TCP/IP, such as Solaris systems, other UNIX^® systems, Microsoft Windows, and Macintosh OS systems

• Systems that are running other trusted operating systems that recognize CIPSO labels

As in the Solaris OS, Trusted Extensions network communications and services can be managed by a naming service. Trusted Extensions adds the following interfaces to Solaris network interfaces:

• Trusted Extensions adds three network configuration databases, tnzonecfg, tnrhdb, and tnrhtp. For details, see Network Configuration Databases in Trusted Extensions.

• The Trusted Extensions version of the naming service switch file, nsswitch.conf, includes entries for the tnrhtp and tnrhdb databases. These entries can be modified to suit each site's configuration.

  Trusted Extensions uses the LDAP naming service to centrally manage configuration files that define hosts, networks, and users. The default nsswitch.conf entries for the trusted network databases for the LDAP naming service follow:

  # Trusted Extensions
  tnrhtp: files ldap
  tnrhdb: files ldap

  The LDAP naming service on a Sun Java System Directory Server is the only fully supported naming service in Trusted Extensions. For information about the use of LDAP on a system that is configured with Trusted Extensions, see Chapter 15, Trusted Extensions and LDAP (Overview).

• Trusted Extensions adds tools to the Solaris Management Console. The console is used to centrally manage zones, hosts, and networks. The network tools are described in Solaris Management Console Tools.

  The Part I, Initial Configuration of Trusted Extensions describes how to define zones and hosts when you configure the network. For additional details, see Chapter 19, Managing Networks in Trusted Extensions (Tasks).

• Trusted Extensions adds commands to administer trusted networking. Trusted Extensions also adds options to the Solaris network commands. For a description of these commands, see Network Commands in Trusted Extensions.

Network Configuration Databases in Trusted Extensions

Trusted Extensions loads three network configuration databases into the kernel. These databases are used in accreditation checks as data is transmitted from one host to another host.

• tnzonecfg – This local database stores zone attributes that are security-related. The attributes for each zone specify the zone label and the zone's access to single-level and multilevel ports. Another attribute handles responses to control messages, such as ping. The labels for zones are defined in the label_encodings file. For more information, see the label_encodings(4) and smtnzonecfg(1M) man pages. For a discussion of multilevel ports, see Zones and Multilevel Ports.

• tnrhtp – This database stores templates that describe the security attributes of hosts and gateways. tnrhtp can be a local database or stored on the LDAP server. Hosts and gateways use the attributes of the destination host and next-hop gateway to enforce MAC when sending traffic. When receiving traffic, hosts and gateways use the attributes of the sender. For details of the security attributes, see Trusted Network Security Attributes. For more information, see the smtnrhtp(1M) man page.

• tnrhdb – This database holds the IP addresses and network prefixes (fallback mechanism) that correspond to all hosts that are allowed to communicate. tnrhdb can be a local database or stored on the LDAP server. Each host or network prefix is assigned a security template from the tnrhtp database. The attributes in the template define the attributes of the assigned host. For more information, see the smtnrhdb(1M) man page.

In Trusted Extensions, the Solaris Management Console has been extended to handle these databases. For details, see Solaris Management Console Tools.

Network Commands in Trusted Extensions

Trusted Extensions adds the following commands to administer trusted networking:

• tnchkdb – This command is used to verify the correctness of the trusted network databases. The tnchkdb command is used whenever you change a security template (tnrhtp), a security template assignment (tnrhdb), or the configuration of a zone (tnzonecfg). The Solaris Management Console tools run this command automatically when a database is modified. For details, see the tnchkdb(1M) man page.

• tnctl – This command can be used to update the trusted network information in the kernel. tnctl is also a system service. A restart with the command svcadm restart /network/tnctl refreshes the kernel cache from the trusted network databases on the local system. The Solaris Management Console tools run this command automatically when a database is modified in the Files scope. For details, see the tnctl(1M) man page.

• tnd – This daemon pulls tnrhdb and tnrhtp information from the LDAP directory. tnd is started at boot time as a service, as in svcadm start /network/tnd. This command also can be used for debugging and for changing the polling interval. For details, see the tnd(1M) man page.

• tninfo – This command displays the details of the current state of the trusted network kernel cache. The output can be filtered by host name, zone, or security template. For details, see the tninfo(1M) man page.

Trusted Extensions adds options to the following Solaris network commands:

• ifconfig – The all-zones interface flag for this command makes the specified interface available to every zone on the system. The appropriate zone to deliver data to is determined by the label that is associated with the data. For details, see the ifconfig(1M) man page.

• netstat – The -R option extends Solaris netstat usage to display Trusted Extensions-specific information, such as security attributes for multilevel sockets and routing table entries. The extended security attributes include the label of the peer, and whether the socket is specific to a zone, or available to several zones. For details, see the netstat(1M) man page.

• route – The -secattr option extends Solaris route usage to display the security attributes of the route. The value of the option has the following format:

  min_sl=label,max_sl=label,doi=integer,cipso

  The cipso keyword is optional and set by default. For details, see the route(1M) man page.

• snoop – As in the Solaris OS, the -v option to this command can be used to display the IP headers in detail. In Trusted Extensions, the headers contain label information.

Trusted Network Security Attributes

Network administration in Trusted Extensions is based on security templates. A security template describes a set of hosts that have common protocols and identical security attributes.

Security attributes are administratively assigned to systems, both hosts and routers, by means of templates. The security administrator administers templates and assigns them to systems. If a system does not have an assigned template, no communications are allowed with that system.

Every template is named, and includes the following:

• A host type of either Unlabeled or CIPSO. The protocol that is used for network communications is determined by the host type of the template.

  The host type is used to determine whether to use CIPSO options and affects MAC. See Host Type and Template Name in Security Templates.

• A set of security attributes that are applied to each host type.

For more detail about host types and security attributes, see Network Security Attributes in Trusted Extensions.