1 =================================== 2 NetLabel CIPSO/IPv4 Protocol Engine 3 =================================== 4 5 Paul Moore, paul.moore@hp.com 6 7 May 17, 2006 8 9 Overview 10 ======== 11 12 The NetLabel CIPSO/IPv4 protocol engine is based on the IETF Commercial 13 IP Security Option (CIPSO) draft from July 16, 1992. A copy of this 14 draft can be found in this directory 15 (draft-ietf-cipso-ipsecurity-01.txt). While the IETF draft never made 16 it to an RFC standard it has become a de-facto standard for labeled 17 networking and is used in many trusted operating systems. 18 19 Outbound Packet Processing 20 ========================== 21 22 The CIPSO/IPv4 protocol engine applies the CIPSO IP option to packets by 23 adding the CIPSO label to the socket. This causes all packets leaving the 24 system through the socket to have the CIPSO IP option applied. The socket's 25 CIPSO label can be changed at any point in time, however, it is recommended 26 that it is set upon the socket's creation. The LSM can set the socket's CIPSO 27 label by using the NetLabel security module API; if the NetLabel "domain" is 28 configured to use CIPSO for packet labeling then a CIPSO IP option will be 29 generated and attached to the socket. 30 31 Inbound Packet Processing 32 ========================= 33 34 The CIPSO/IPv4 protocol engine validates every CIPSO IP option it finds at the 35 IP layer without any special handling required by the LSM. However, in order 36 to decode and translate the CIPSO label on the packet the LSM must use the 37 NetLabel security module API to extract the security attributes of the packet. 38 This is typically done at the socket layer using the 'socket_sock_rcv_skb()' 39 LSM hook. 40 41 Label Translation 42 ================= 43 44 The CIPSO/IPv4 protocol engine contains a mechanism to translate CIPSO security 45 attributes such as sensitivity level and category to values which are 46 appropriate for the host. These mappings are defined as part of a CIPSO 47 Domain Of Interpretation (DOI) definition and are configured through the 48 NetLabel user space communication layer. Each DOI definition can have a 49 different security attribute mapping table. 50 51 Label Translation Cache 52 ======================= 53 54 The NetLabel system provides a framework for caching security attribute 55 mappings from the network labels to the corresponding LSM identifiers. The 56 CIPSO/IPv4 protocol engine supports this caching mechanism.
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