57 lines · plain
1===================================2NetLabel CIPSO/IPv4 Protocol Engine3===================================4 5Paul Moore, paul.moore@hp.com6 7May 17, 20068 9Overview10========11 12The NetLabel CIPSO/IPv4 protocol engine is based on the IETF Commercial13IP Security Option (CIPSO) draft from July 16, 1992. A copy of this14draft can be found in this directory15(draft-ietf-cipso-ipsecurity-01.txt). While the IETF draft never made16it to an RFC standard it has become a de-facto standard for labeled17networking and is used in many trusted operating systems.18 19Outbound Packet Processing20==========================21 22The CIPSO/IPv4 protocol engine applies the CIPSO IP option to packets by23adding the CIPSO label to the socket. This causes all packets leaving the24system through the socket to have the CIPSO IP option applied. The socket's25CIPSO label can be changed at any point in time, however, it is recommended26that it is set upon the socket's creation. The LSM can set the socket's CIPSO27label by using the NetLabel security module API; if the NetLabel "domain" is28configured to use CIPSO for packet labeling then a CIPSO IP option will be29generated and attached to the socket.30 31Inbound Packet Processing32=========================33 34The CIPSO/IPv4 protocol engine validates every CIPSO IP option it finds at the35IP layer without any special handling required by the LSM. However, in order36to decode and translate the CIPSO label on the packet the LSM must use the37NetLabel security module API to extract the security attributes of the packet.38This is typically done at the socket layer using the 'socket_sock_rcv_skb()'39LSM hook.40 41Label Translation42=================43 44The CIPSO/IPv4 protocol engine contains a mechanism to translate CIPSO security45attributes such as sensitivity level and category to values which are46appropriate for the host. These mappings are defined as part of a CIPSO47Domain Of Interpretation (DOI) definition and are configured through the48NetLabel user space communication layer. Each DOI definition can have a49different security attribute mapping table.50 51Label Translation Cache52=======================53 54The NetLabel system provides a framework for caching security attribute55mappings from the network labels to the corresponding LSM identifiers. The56CIPSO/IPv4 protocol engine supports this caching mechanism.57