1NetLabel CIPSO/IPv4 Protocol Engine 2============================================================================== 3Paul Moore, paul.moore@hp.com 4 5May 17, 2006 6 7 * Overview 8 9The NetLabel CIPSO/IPv4 protocol engine is based on the IETF Commercial IP 10Security Option (CIPSO) draft from July 16, 1992. A copy of this draft can be 11found in this directory, consult '00-INDEX' for the filename. While the IETF 12draft never made it to an RFC standard it has become a de-facto standard for 13labeled networking and is used in many trusted operating systems. 14 15 * Outbound Packet Processing 16 17The CIPSO/IPv4 protocol engine applies the CIPSO IP option to packets by 18adding the CIPSO label to the socket. This causes all packets leaving the 19system through the socket to have the CIPSO IP option applied. The socket's 20CIPSO label can be changed at any point in time, however, it is recommended 21that it is set upon the socket's creation. The LSM can set the socket's CIPSO 22label by using the NetLabel security module API; if the NetLabel "domain" is 23configured to use CIPSO for packet labeling then a CIPSO IP option will be 24generated and attached to the socket. 25 26 * Inbound Packet Processing 27 28The CIPSO/IPv4 protocol engine validates every CIPSO IP option it finds at the 29IP layer without any special handling required by the LSM. However, in order 30to decode and translate the CIPSO label on the packet the LSM must use the 31NetLabel security module API to extract the security attributes of the packet. 32This is typically done at the socket layer using the 'socket_sock_rcv_skb()' 33LSM hook. 34 35 * Label Translation 36 37The CIPSO/IPv4 protocol engine contains a mechanism to translate CIPSO security 38attributes such as sensitivity level and category to values which are 39appropriate for the host. These mappings are defined as part of a CIPSO 40Domain Of Interpretation (DOI) definition and are configured through the 41NetLabel user space communication layer. Each DOI definition can have a 42different security attribute mapping table. 43 44 * Label Translation Cache 45 46The NetLabel system provides a framework for caching security attribute 47mappings from the network labels to the corresponding LSM identifiers. The 48CIPSO/IPv4 protocol engine supports this caching mechanism. 49