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