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Documentation / netlabel / cipso_ipv4.txt




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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 EST.

1	NetLabel CIPSO/IPv4 Protocol Engine
2	==============================================================================
3	Paul Moore, paul.moore@hp.com
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.
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